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Sample records for engineering properties experiment

  1. Lunar surface engineering properties experiment definition

    NASA Technical Reports Server (NTRS)

    Mitchell, J. K.; Goodman, R. E.; Hurlbut, F. C.; Houston, W. N.; Willis, D. R.; Witherspoon, P. A.; Hovland, H. J.

    1971-01-01

    Research on the mechanics of lunar soils and on developing probes to determine the properties of lunar surface materials is summarized. The areas of investigation include the following: soil simulation, soil property determination using an impact penetrometer, soil stabilization using urethane foam or phenolic resin, effects of rolling boulders down lunar slopes, design of borehole jack and its use in determining failure mechanisms and properties of rocks, and development of a permeability probe for measuring fluid flow through porous lunar surface materials.

  2. Engineering support activities for the Apollo 17 Surface Electrical Properties Experiment.

    NASA Technical Reports Server (NTRS)

    Cubley, H. D.

    1972-01-01

    Description of the engineering support activities which were required to ensure fulfillment of objectives specified for the Apollo 17 SEP (Surface Electrical Properties) Experiment. Attention is given to procedural steps involving verification of hardware acceptability to the astronauts, computer simulation of the experiment hardware, field trials, receiver antenna pattern measurements, and the qualification test program.

  3. Properties of jet engine combustion particles during the PartEmis experiment: Hygroscopicity at subsaturated conditions

    NASA Astrophysics Data System (ADS)

    Gysel, M.; Nyeki, S.; Weingartner, E.; Baltensperger, U.; Giebl, H.; Hitzenberger, R.; Petzold, A.; Wilson, C. W.

    2003-06-01

    Hygroscopic properties of combustion particles were measured online with a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA) during PartEmis jet engine combustor experiments. The combustor was operated at old and modern cruise conditions with fuel sulfur contents (FSC) of 50, 410 and 1270 μg g-1, and hygroscopic growth factors (HGF) of particles with different dry diameters were investigated at relative humidities RH <= 95%. HGFs increased strongly with increasing FSC (HGF[95% RH, 50 nm, modern cruise] = 1.01 and 1.16 for low and high FSC, respectively), and decreased with increasing particle size at fixed FSC, whereas no significant difference was detected between old and modern cruise. HGFs agreed well with a two-parameter theoretical model which provided an estimate of the sulfuric acid content of dry particles, indicating a nearly linear dependence on FSC.

  4. Properties of jet engine combustion particles during the PartEmis experiment: Particle size spectra (d > 15 nm) and volatility

    NASA Astrophysics Data System (ADS)

    Nyeki, S.; Gysel, M.; Weingartner, E.; Baltensperger, U.; Hitzenberger, R.; Petzold, A.; Wilson, C. W.

    2004-09-01

    Size distributions (d > 15 nm) and volatile properties of combustion particles were measured during test-rig experiments on a jet engine, consisting of a combustor and three simulated turbine stages (HES). The combustor was operated to simulate legacy (inlet temperature 300°C) and contemporary (500°C) cruise conditions, using kerosene with three different fuel sulfur contents (FSC; 50, 400 and 1300 μg g-1). Measurements found that contemporary cruise conditions resulted in lower number emission indices (EIN15) and higher geometric mean particle diameter (dG) than for legacy conditions. Increasing FSC resulted in an overall increase in EIN15 and decrease in dG. The HES stages or fuel additive (APA101) had little influence on EIN15 or dG, however, this is uncertain due to the measurement variability. EIN15 for non-volatile particles was largely independent of all examined conditions.

  5. Subterranean stress engineering experiments

    SciTech Connect

    Campbell, J.R.; Colgate, S.A.; Wheat, B.M.

    1980-01-01

    The state of stress in a subterranean rock mass has classically been assumed to be constant at best. In soil with a high clay content, preconsolidation and drainage methods can lead to more stable foundation material, but methods for engineering the stresses in large masses of rock are not well known. This paper shows the results from an experiment designed to alter the in situ rock stress field in an oil shale mine. This was done by hydrofracturing the rock by use of a packed-well injection system and then propping the crack open with a thixotropic gel, which slowly hardened to the consistency of cement. Successive hydrofracture and high-pressure grouting resulted in an overstressed region. Well-head injection pressures, surface tilts, injection rates, and subterranean strains were measured and recorded on floppy disk by a Z-80 microprocessor. The results were then transmitted to the large computer system at the Los Alamos Scientific Laboratory (LASL). To put the data in a more useful form, computer-generated movies of the tilts and strains were made by use of computer graphics developed at LASL. The purpose of this paper is to present results from the Single Large Instrumented Test conducted in the Colony Oil Shale Mine near Rifle, Colorado. 13 figures.

  6. Summer Work Experience: Determining Methane Combustion Mechanisms and Sub-Scale Diffuser Properties for Space Transporation System Engine Testing

    NASA Technical Reports Server (NTRS)

    Williams, Powtawche N.

    1998-01-01

    To assess engine performance during the testing of Space Shuttle Main Engines (SSMEs), the design of an optimal altitude diffuser is studied for future Space Transportation Systems (STS). For other Space Transportation Systems, rocket propellant using kerosene is also studied. Methane and dodecane have similar reaction schemes as kerosene, and are used to simulate kerosene combustion processes at various temperatures. The equations for the methane combustion mechanism at high temperature are given, and engine combustion is simulated on the General Aerodynamic Simulation Program (GASP). The successful design of an altitude diffuser depends on the study of a sub-scaled diffuser model tested through two-dimensional (2-D) flow-techniques. Subroutines given calculate the static temperature and pressure at each Mach number within the diffuser flow. Implementing these subroutines into program code for the properties of 2-D compressible fluid flow determines all fluid characteristics, and will be used in the development of an optimal diffuser design.

  7. Evaluating word semantic properties using Sketch Engine

    NASA Astrophysics Data System (ADS)

    Stoykova, Velislava; Simkova, Maria

    2015-02-01

    The paper describes approach to use statistically-based tools incorporated into Sketch Engine system for electronic text corpora processing to mining big textual data for search and extract word semantic properties. It presents and compares series of word search experiments using different statistical approaches and evaluates results for Bulgarian language EUROPARL 7 Corpus search to extract word semantic properties. Finally, the methodology is extended for multilingual application using Slovak language EUROPARL 7 Corpus.

  8. Engineering Sustainable Engineers through the Undergraduate Experience

    ERIC Educational Resources Information Center

    Weatherton, Yvette Pearson; Sattler, Melanie; Mattingly, Stephen; Chen, Victoria; Rogers, Jamie; Dennis, Brian

    2012-01-01

    In order to meet the challenges of sustainable development, our approach to education must be modified to equip students to evaluate alternatives and devise solutions that meet multi-faceted requirements. In 2009, faculty in the Departments of Civil, Industrial and Mechanical Engineering at the University of Texas at Arlington began implementation…

  9. Cryogenics Research and Engineering Experience

    NASA Technical Reports Server (NTRS)

    Toro Medina, Jaime A.

    2013-01-01

    Energy efficient storage, transfer and use of cryogens and cryogenic propellants on Earth and in space have a direct impact on NASA, government and commercial programs. Research and development on thermal insulation, propellant servicing, cryogenic components, material properties and sensing technologies provides industry, government and research institutions with the cross-cutting technologies to manage low-temperature applications. Under the direction of the Cryogenic Testing Lab at Kennedy Space Center, the work experience acquired allowed me to perform research, testing, design and analysis of current and future cryogenic technologies to be applied in several projects.

  10. Infusing Real World Experiences into Engineering Education

    ERIC Educational Resources Information Center

    National Academies Press, 2012

    2012-01-01

    The aim of this report is to encourage enhanced richness and relevance of the undergraduate engineering education experience, and thus produce better-prepared and more globally competitive graduates, by providing practical guidance for incorporating real world experience in US engineering programs. The report, a collaborative effort of the…

  11. ABB Combustion Engineering`s nuclear experience and technologies

    SciTech Connect

    Matzie, R.A.

    1994-12-31

    ABB Combustion Engineering`s nuclear experience and technologies are outlined. The following topics are discussed: evolutionary approach using proven technology, substantial improvement to plant safety, utility perspective up front in developing design, integrated design, competitive plant cost, operability and maintainability, standardization, and completion of US NRC technical review.

  12. Advancing Intercultural Competency: Canadian Engineering Employers' Experiences with Immigrant Engineers

    ERIC Educational Resources Information Center

    Friesen, Marcia; Ingram, Sandra

    2013-01-01

    This paper explores Canadian engineering employers' perceptions of and experiences with internationally educated engineers (recent immigrants to Canada) employed in their organisations for varying lengths of time. Qualitative data were collected from employers using focus group methodology. Findings reflected employers' observations of culturally…

  13. Engineering data management: Experience and projections

    NASA Technical Reports Server (NTRS)

    Jefferson, D. K.; Thomson, B.

    1978-01-01

    Experiences in developing a large engineering data management system are described. Problems which were encountered are presented and projected to future systems. Business applications involving similar types of data bases are described. A data base management system architecture proposed by the business community is described and its applicability to engineering data management is discussed. It is concluded that the most difficult problems faced in engineering and business data management can best be solved by cooperative efforts.

  14. Advancing intercultural competency: Canadian engineering employers' experiences with immigrant engineers

    NASA Astrophysics Data System (ADS)

    Friesen, Marcia; Ingram, Sandra

    2013-05-01

    This paper explores Canadian engineering employers' perceptions of and experiences with internationally educated engineers (recent immigrants to Canada) employed in their organisations for varying lengths of time. Qualitative data were collected from employers using focus group methodology. Findings reflected employers' observations of culturally different behaviours and characteristics in their internationally educated employees, employers' reactions to cultural differences ranging from negative attributions to tolerance, and the implementation of largely ad hoc intra-organisational strategies for managing cultural differences in employer-employee relationships. Findings exposed the lack of corporate intercultural competency in the Canadian engineering profession. Equity and gatekeeping implications are discussed.

  15. Experience of Cooperative Learning in Engineering

    ERIC Educational Resources Information Center

    Maceiras, Rocio; Cancela, Angeles; Urrejola, Santiago; Sanchez, Angel

    2011-01-01

    The objective of this work is to share the authors' experience towards a different mode of teaching/learning method. Cooperative learning (Jigsaw) was employed on the University of Vigo's fourth-year engineering students. The results of the experience show that cooperative learning is quite a viable alternative to the classical way of lecturing at…

  16. Centrifugal Pump Experiment for Chemical Engineering Undergraduates

    ERIC Educational Resources Information Center

    Vanderslice, Nicholas; Oberto, Richard; Marrero, Thomas R.

    2012-01-01

    The purpose of this paper is to describe a Centrifugal Pump Experiment that provided an experiential learning experience to chemical engineering undergraduates at the University of Missouri in the spring of 2010 in the Unit Operations Laboratory course. Lab equipment was used by senior students with computer-based data and control technology. In…

  17. A First Chemical Engineering Lab Experience.

    ERIC Educational Resources Information Center

    Punzi, Vito L.

    1987-01-01

    Describes a simple thermodynamics experiment recommended for use in beginning chemical engineering laboratory courses. Outlines the theory behind the experiment, which determines the specific heat of a liquid. Discusses the construction, operation, and maintenance of the apparatus involved, along with the experimental procedure. (TW)

  18. Computational Experiments for Science and Engineering Education

    NASA Technical Reports Server (NTRS)

    Xie, Charles

    2011-01-01

    How to integrate simulation-based engineering and science (SBES) into the science curriculum smoothly is a challenging question. For the importance of SBES to be appreciated, the core value of simulations-that they help people understand natural phenomena and solve engineering problems-must be taught. A strategy to achieve this goal is to introduce computational experiments to the science curriculum to replace or supplement textbook illustrations and exercises and to complement or frame hands-on or wet lab experiments. In this way, students will have an opportunity to learn about SBES without compromising other learning goals required by the standards and teachers will welcome these tools as they strengthen what they are already teaching. This paper demonstrates this idea using a number of examples in physics, chemistry, and engineering. These exemplary computational experiments show that it is possible to create a curriculum that is both deeper and wider.

  19. Engineering optical properties of semiconductor metafilm superabsorbers

    NASA Astrophysics Data System (ADS)

    Kim, Soo Jin; Fan, Pengyu; Kang, Ju-Hyung; Brongersma, Mark L.

    2016-04-01

    Light absorption in ultrathin layer of semiconductor has been considerable interests for many years due to its potential applications in various optical devices. In particular, there have been great efforts to engineer the optical properties of the film for the control of absorption spectrums. Whereas the isotropic thin films have intrinsic optical properties that are fixed by materials' properties, metafilm that are composed by deep subwavelength nano-building blocks provides significant flexibilities in controlling the optical properties of the designed effective layers. Here, we present the ultrathin semiconductor metafilm absorbers by arranging germanium (Ge) nanobeams in deep subwavelength scale. Resonant properties of high index semiconductor nanobeams play a key role in designing effective optical properties of the film. We demonstrate this in theory and experimental measurements to build a designing rule of efficient, controllable metafilm absorbers. The proposed strategy of engineering optical properties could open up wide range of applications from ultrathin photodetection and solar energy harvesting to the diverse flexible optoelectronics.

  20. National Educators' Workshop. Update 92: Standard Experiments in Engineering Materials Science and Technology

    NASA Technical Reports Server (NTRS)

    Gardner, James E. (Compiler); Jacobs, James A. (Compiler); Craig, Douglas F. (Compiler)

    1993-01-01

    This document contains a collection of experiments presented and demonstrated at the workshop. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community.

  1. The Transformative Experience in Engineering Education

    NASA Astrophysics Data System (ADS)

    Goodman, Katherine Ann

    This research evaluates the usefulness of transformative experience (TE) in engineering education. With TE, students 1) apply ideas from coursework to everyday experiences without prompting (motivated use); 2) see everyday situations through the lens of course content (expanded perception); and 3) value course content in new ways because it enriches everyday affective experience (affective value). In a three-part study, we examine how engineering educators can promote student progress toward TE and reliably measure that progress. For the first study, we select a mechanical engineering technical elective, Flow Visualization, that had evidence of promoting expanded perception of fluid physics. Through student surveys and interviews, we compare this elective to the required Fluid Mechanics course. We found student interest in fluids fell into four categories: complexity, application, ubiquity, and aesthetics. Fluid Mechanics promotes interest from application, while Flow Visualization promotes interest based in ubiquity and aesthetics. Coding for expanded perception, we found it associated with students' engineering identity, rather than a specific course. In our second study, we replicate atypical teaching methods from Flow Visualization in a new design course: Aesthetics of Design. Coding of surveys and interviews reveals that open-ended assignments and supportive teams lead to increased ownership of projects, which fuels risk-taking, and produces increased confidence as an engineer. The third study seeks to establish parallels between expanded perception and measurable perceptual expertise. Our visual expertise experiment uses fluid flow images with both novices and experts (students who had passed fluid mechanics). After training, subjects sort images into laminar and turbulent categories. The results demonstrate that novices learned to sort the flow stimuli in ways similar to subjects in prior perceptual expertise studies. In contrast, the experts' significantly

  2. Semiconductor alloys - Structural property engineering

    NASA Technical Reports Server (NTRS)

    Sher, A.; Van Schilfgaarde, M.; Berding, M.; Chen, A.-B.

    1987-01-01

    Semiconductor alloys have been used for years to tune band gaps and average bond lengths to specific applications. Other selection criteria for alloy composition, and a growth technique designed to modify their structural properties, are presently considered. The alloys Zn(1-y)Cd(y)Te and CdSe(y)Te(1-y) are treated as examples.

  3. Gasdynamic Mirror (GDM) Fusion Propulsion Engine Experiment

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The Gasdynamic Mirror, or GDM, is an example of a magnetic mirror-based fusion propulsion system. Its design is primarily consisting of a long slender solenoid surrounding a vacuum chamber that contains plasma. The bulk of the fusion plasma is confined by magnetic field generated by a series of toroidal-shaped magnets in the center section of the device. the purpose of the GDM Fusion Propulsion Experiment is to confirm the feasibility of the concept and to demonstrate many of the operational characteristics of a full-size plasma can be confined within the desired physical configuration and still reman stable. This image shows an engineer from Propulsion Research Technologies Division at Marshall Space Flight Center inspecting solenoid magnets-A, an integrate part of the Gasdynamic Mirror Fusion Propulsion Engine Experiment.

  4. Parts Engineering Experiences, Philosophies and Trends

    NASA Technical Reports Server (NTRS)

    Shaw, Harry; Day, John H. (Technical Monitor)

    2000-01-01

    This document is the presentation viewgraphs of the NASA presentations to NASDA, outlining the philosophy and trends of the experiences with engineering parts. Included in the presentations: are (1) the assurance of COTS boards for Space flight, and (2) Peer Review for Ice, Cloud and land Elevation Satellite (ICESat) GPS flight receivers EEE parts. The emphasis is on the methods for qualification of available parts for space flight.

  5. E-Standards For Mass Properties Engineering

    NASA Technical Reports Server (NTRS)

    Cerro, Jeffrey A.

    2008-01-01

    A proposal is put forth to promote the concept of a Society of Allied Weight Engineers developed voluntary consensus standard for mass properties engineering. This standard would be an e-standard, and would encompass data, data manipulation, and reporting functionality. The standard would be implemented via an open-source SAWE distribution site with full SAWE member body access. Engineering societies and global standards initiatives are progressing toward modern engineering standards, which become functioning deliverable data sets. These data sets, if properly standardized, will integrate easily between supplier and customer enabling technically precise mass properties data exchange. The concepts of object-oriented programming support all of these requirements, and the use of a JavaTx based open-source development initiative is proposed. Results are reported for activity sponsored by the NASA Langley Research Center Innovation Institute to scope out requirements for developing a mass properties engineering e-standard. An initial software distribution is proposed. Upon completion, an open-source application programming interface will be available to SAWE members for the development of more specific programming requirements that are tailored to company and project requirements. A fully functioning application programming interface will permit code extension via company proprietary techniques, as well as through continued open-source initiatives.

  6. Argonne Plasma Engineering Experiment (APEX) Tokamak

    SciTech Connect

    Norem, J.H.; Balka, L.J.; Kulovitz, E.E.; Magill, S.R.; McGhee, D.G.; Moretti, A.; Praeg, W.F.

    1981-03-01

    The Argonne Plasma Engineering Experiment (APEX) Tokamak was designed to provide hot plasmas for reactor-relevant experiments with rf heating (current drive) and plasma wall experiments, principally in-situ low-Z wall coating and maintenance. The device, sized to produce energetic plasmas at minimum cost, is small (R = 51 cm, r = 15 cm) but capable of high currents (100 kA) and long pulse durations (100 ms). A design using an iron central core with no return legs, pure tension tapewound toroidal field coils, digital radial position control, and UHV vacuum technology was used. Diagnostics include monochrometers, x-ray detectors, and a microwave interferometer and radiometer for density and temperature measurements. Stable 100 ms shots were produced with electron temperatures in the range 500 to 1000 eV. Initial results included studies of thermal desorption and recoating of wall materials.

  7. Teaching Ethics to Engineers: A Socratic Experience.

    PubMed

    Génova, Gonzalo; González, M Rosario

    2016-04-01

    In this paper we present the authors' experience of teaching a course in Ethics for Engineers, which has been delivered four times in three different universities in Spain and Chile. We begin by presenting the material context of the course (its place within the university program, the number of students attending, its duration, etc.), and especially the intellectual background of the participating students, in terms of their previous understanding of philosophy in general, and of ethics in particular. Next we set out the objectives of the course and the main topics addressed, as well as the methodology and teaching resources employed to have students achieve a genuine philosophical reflection on the ethical aspects of the profession, starting from their own mindset as engineers. Finally we offer some results based on opinion surveys of the students, as well as a more personal assessment by the authors, recapitulating the most significant achievements of the course and indicating its underlying Socratic structure.

  8. Experience of cooperative learning in engineering

    NASA Astrophysics Data System (ADS)

    Maceiras, Rocio; Cancela, Angeles; Urréjola, Santiago; Sánchez, Angel

    2011-03-01

    The objective of this work is to share the authors' experience towards a different mode of teaching/learning method. Cooperative learning (Jigsaw) was employed on the University of Vigo's fourth-year engineering students. The results of the experience show that cooperative learning is quite a viable alternative to the classical way of lecturing at the university when the number of students is not too high. The authors' observation indicates that students did not show a lot of interest towards the new learning style but their resistance changed once they began the activity. The Jigsaw method has proved to be a useful tool for improving the learning process so that students have the opportunity to participate actively in the learning activities.

  9. Engineered Proteins: Redox Properties and Their Applications

    PubMed Central

    Prabhulkar, Shradha; Tian, Hui; Wang, Xiaotang; Zhu, Jun-Jie

    2012-01-01

    Abstract Oxidoreductases and metalloproteins, representing more than one third of all known proteins, serve as significant catalysts for numerous biological processes that involve electron transfers such as photosynthesis, respiration, metabolism, and molecular signaling. The functional properties of the oxidoreductases/metalloproteins are determined by the nature of their redox centers. Protein engineering is a powerful approach that is used to incorporate biological and abiological redox cofactors as well as novel enzymes and redox proteins with predictable structures and desirable functions for important biological and chemical applications. The methods of protein engineering, mainly rational design, directed evolution, protein surface modifications, and domain shuffling, have allowed the creation and study of a number of redox proteins. This review presents a selection of engineered redox proteins achieved through these methods, resulting in a manipulation in redox potentials, an increase in electron-transfer efficiency, and an expansion of native proteins by de novo design. Such engineered/modified redox proteins with desired properties have led to a broad spectrum of practical applications, ranging from biosensors, biofuel cells, to pharmaceuticals and hybrid catalysis. Glucose biosensors are one of the most successful products in enzyme electrochemistry, with reconstituted glucose oxidase achieving effective electrical communication with the sensor electrode; direct electron-transfer-type biofuel cells are developed to avoid thermodynamic loss and mediator leakage; and fusion proteins of P450s and redox partners make the biocatalytic generation of drug metabolites possible. In summary, this review includes the properties and applications of the engineered redox proteins as well as their significance and great potential in the exploration of bioelectrochemical sensing devices. Antioxid. Redox Signal. 17, 1796–1822. PMID:22435347

  10. Engineering properties of inorganic polymer concretes (IPCs)

    SciTech Connect

    Sofi, M.; Deventer, J.S.J. van . E-mail: jannie@unimelb.edu.au; Mendis, P.A. . E-mail: pamendis@unimelb.edu.au; Lukey, G.C.

    2007-02-15

    This paper presents the engineering properties of inorganic polymer concretes (IPCs) with a compressive strength of 50 MPa. The study includes a determination of the modulus of elasticity, Poisson's ratio, compressive strength, and the splitting tensile strength and flexural strength of IPCs, formulated using three different sources of Class-F fly ash. Six IPC mix designs were adopted to evaluate the effects of the inclusion of coarse aggregates and granulated blast furnace slag into the mixes. A total of 90 cylindrical and 24 small beam specimens were investigated, and all tests were carried out pursuant to the relevant Australian Standards. Although some variability between the mixes was observed, the results show that, in most cases, the engineering properties of IPCs compare favorably to those predicted by the relevant Australian Standards for concrete mixtures.

  11. Socialization Experiences Resulting from Doctoral Engineering Teaching Assistantships

    ERIC Educational Resources Information Center

    Mena, Irene B.; Diefes-Dux, Heidi A.; Capobianco, Brenda M.

    2013-01-01

    The purpose of this study was to explore and characterize the types of socialization experiences that result from engineering teaching assistantships. Using situated learning and communities of practice as the theoretical framework, this study highlights the experiences of 28 engineering doctoral students who worked as engineering teaching…

  12. Learning from Fellow Engineering Students Who Have Current Professional Experience

    ERIC Educational Resources Information Center

    Davies, John W.; Rutherford, Ursula

    2012-01-01

    This paper presents an investigation of how experience-led content in an engineering degree can be strengthened by creating opportunities for engineering students to benefit from the knowledge, skills and resources of students with current professional experience. Students who study civil engineering part-time at Coventry University (while also…

  13. An Engineered Anisotropic Nanofilm with Unidirectional Wetting Properties

    DTIC Science & Technology

    2010-01-01

    ARTICLES PUBLISHED ONLINE: 10 OCTOBER 2010 | DOI: 10.1038/NMAT2864 An engineered anisotropic nanofilm with unidirectional wetting properties Niranjan...body3. Engineering synthetic materials with such anisotropic adhesive properties has led to advances in digitalmicrofluidic devices5,6 andmedicine7,8...The anisotropic wetting properties of existing engineered surfaces are derived either from spatial gradients (for example, temperature, surface

  14. Teenage experiments contaminate suburban property

    SciTech Connect

    Kassel, D.; Sass, W.; Lall, P.C.; Jensen, L.; Mitchell, J.

    1996-06-01

    In August 1994, 18-year-old Brian Cooper (not his real name) was detained by police in Clinton Township Michigan. When the police searched his car, they discovered a locked tool box and other containers that Brian said contained radioactive material resulting from experiments he had conducted with the radioactive material from, primarily, consumer products. From the ages 14 to 18, Brian spent his spare time at his Union Lake, Michigan, home attempting to concentrate, burn, chemically alter, and experiment with the thorium from hundreds of lantern mantles, radium from various luminescent sources and clock dials, smoke detector sources, and radioactive materials from natural ores. In the process, he had contaminated a wooden shed in his backyard and his bedroom, and injured and exposed himself. In 1995, EPA; their emergency response contractor, Ecology and Environment, Inc.; and the Michigan Department of Public Health performed an emergency assessment and removal at the property. The response and removal were conducted cost-effectively and generated approximately 10 cubic yards of radioactive waste.

  15. Fuel property effects on engine combustion processes. Final report

    SciTech Connect

    Cernansky, N.P.; Miller, D.L.

    1995-04-27

    A major obstacle to improving spark ignition engine efficiency is the limitations on compression ratio imposed by tendency of hydrocarbon fuels to knock (autoignite). A research program investigated the knock problem in spark ignition engines. Objective was to understand low and intermediate temperature chemistry of combustion processes relevant to autoignition and knock and to determine fuel property effects. Experiments were conducted in an optically and physically accessible research engine, static reactor, and an atmospheric pressure flow reactor (APFR). Chemical kinetic models were developed for prediction of species evolution and autoignition behavior. The work provided insight into low and intermediate temperature chemistry prior to autoignition of n-butane, iso-butane, n-pentane, 1-pentene, n-heptane, iso-octane and some binary blends. Study of effects of ethers (MTBE, ETBE, TAME and DIPE ) and alcohols (methanol and ethanol) on the oxidation and autoignition of primary reference fuel (PRF) blends.

  16. Engineering electrical properties of graphene: chemical approaches

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Jin; Kim, Yuna; Novoselov, Konstantin; Hong, Byung Hee

    2015-12-01

    To ensure the high performance of graphene-based devices, it is necessary to engineer the electrical properties of graphene with enhanced conductivity, controlled work function, opened or closed bandgaps, etc. This can be performed by various non-covalent chemical approaches, including molecular adsorption, substrate-induced doping, polymerization on graphene, deposition of metallic thin films or nanoparticles, etc. In addition, covalent approaches such as the substitution of carbon atoms with boron or nitrogen and the functionalization with hydrogen or fluorine are useful to tune the bandgaps more efficiently, with better uniformity and stability. In this review, representative examples of chemically engineered graphene and its device applications will be reviewed, and remaining challenges will be discussed.

  17. Experience Engineering: An Engineering Course for Non-Majors

    ERIC Educational Resources Information Center

    Hargrove-Leak, Sirena

    2012-01-01

    The engineering profession continues to struggle to attract new talent, in part because it is not well understood by the general public and often viewed in a negative light. Therefore, engineering professionals have called for new approaches promote better understanding and change negative perceptions. One suggested approach is for engineering…

  18. Experience with low cost jet engines

    NASA Technical Reports Server (NTRS)

    Cummings, R. L.

    1972-01-01

    A summary is given of the results of a NASA program for reducing the cost of turbojet and turbofan engines. The design, construction, and testing of a simple turbojet, designed for use in missiles, is described. Low cost axial stage fabrication, the design of a fan jet engine suitable for propulsion of light aircraft, and application of such engines to provide higher flight speeds, are discussed.

  19. Demonstration Experiments with a Stirling Engine.

    ERIC Educational Resources Information Center

    Deacon, Christopher G.; And Others

    1994-01-01

    Describes an investigation with the primary purpose of allowing students to generate and interpret a pressure/volume diagram of a Stirling engine. Explains how the Stirling engine can be used to demonstrate the principles of operation of a refrigerator and a heat pump. (DDR)

  20. Connecting Students' Background Experiences to Engineering Design

    ERIC Educational Resources Information Center

    Sias, Christina; Wilson- Lopez, Amy; Mejia, Joel

    2016-01-01

    Many youth do not pursue engineering because they do not see how it connects to their lives and interests. Concerned about this problem, the National Research Council (2012) suggested ways that teachers can make engineering more relevant and accessible to youth who have not traditionally pursued careers in this field. According to the National…

  1. Socialization Experiences Resulting from Engineering Teaching Assistantships at Purdue University

    ERIC Educational Resources Information Center

    Mena, Irene B.

    2010-01-01

    The purpose of this study was to explore and understand the types of socialization experiences that result from engineering teaching assistantships. Using situated learning as the theoretical framework and phenomenology as the methodological framework, this study highlights the experiences of 28 engineering doctoral students who worked as…

  2. Enhancing the Undergraduate Computing Experience in Chemical Engineering CACHE Corporation

    ERIC Educational Resources Information Center

    Edgar, Thomas F.

    2006-01-01

    This white paper focuses on the integration and enhancement of the computing experience for undergraduates throughout the chemical engineering curriculum. The computing experience for undergraduates in chemical engineering should have continuity and be coordinated from course to course, because a single software solution is difficult to achieve in…

  3. National Educators' Workshop: Update 1997. Standard Experiments in Engineering Materials, Science, and Technology

    NASA Technical Reports Server (NTRS)

    Gardner, James E. (Compiler); Freeman, Ginger L. (Compiler); Jacobs, James A. (Compiler); Miller, Alan G. (Compiler); Smith, Brian W. (Compiler)

    1998-01-01

    This document contains a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 97, held at Boeing Commercial Airplane Group, Seattle, Washington, on November 2-5, 1997. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community.

  4. National Educators' Workshop: Update 1989 Standard Experiments in Engineering Materials Science and Technology

    NASA Technical Reports Server (NTRS)

    Gardner, James E. (Compiler); Jacobs, James A. (Compiler)

    1990-01-01

    Presented here is a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 89, held October 17 to 19, 1989 at the National Aeronautics and Space Administration, Hampton, Virginia. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community.

  5. National Educators' Workshop: Update 1991. Standard Experiments in Engineering Materials Science and Technology

    NASA Technical Reports Server (NTRS)

    Gardner, James E. (Compiler); Jacobs, James A. (Compiler); Stiegler, James O. (Compiler)

    1992-01-01

    Given here is a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 91, held at the Oak Ridge National Laboratory on November 12-14, 1991. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community.

  6. National Educators' Workshop: Update 1993. Standard Experiments in Engineering Materials Science and Technology

    NASA Technical Reports Server (NTRS)

    Gardner, James E. (Compiler); Jacobs, James A. (Compiler)

    1994-01-01

    This document contains a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 93 held at the NASA Langley Research Center in Hampton, Virginia, on November 3-5, 1993. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community.

  7. National Educators' Workshop: Update 1988. Standard Experiments in Engineering Materials Science and Technology

    NASA Technical Reports Server (NTRS)

    Gardner, James E. (Compiler); Jacobs, James A. (Compiler)

    1990-01-01

    Presented here is a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 88, held May 10 to 12, 1988 at the National Institute of Standards and Technology (NIST), Gaithersberg, Maryland. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community.

  8. National Educators' Workshop: Update 1994. Standard experiments in engineering materials science and technology

    NASA Technical Reports Server (NTRS)

    Gardner, James E. (Compiler); Jacobs, James A. (Compiler); Fraker, Anna C. (Compiler)

    1995-01-01

    This document contains a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 94. The experiments relate to the nature and properties of engineering materials and provide information to assist in teaching about materials in the education community.

  9. National Educators' Workshop: Update 95. Standard Experiments in Engineering Materials Science and Technology

    NASA Technical Reports Server (NTRS)

    Gardner, James E. (Compiler); Jacobs, James A.; Karnitz, Michael A.

    1996-01-01

    This document contains a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 95. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community.

  10. Engineering optical properties using plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Tamma, Venkata Ananth

    Plasmonic nanostructures can be engineered to take on unusual optical properties not found in natural materials. The optical responses of plasmonic materials are functions of the structural parameters and symmetry of the nanostructures, material parameters of the nanostructure and its surroundings and the incidence angle, frequency and polarization state of light. The scattering and hence the visibility of an object could be reduced by coating it with a plasmonic material. In this thesis, presented is an optical frequency scattering cancelation device composed of a silicon nanorod coated by a plasmonic gold nanostructure. The principle of operation was theoretically analyzed using Mie theory and the device design was verified by extensive numerical simulations. The device was fabricated using a combination of nanofabrication techniques such as electron beam lithography and focused ion beam milling. The optical responses of the scattering cancelation device and a control sample of bare silicon rod were directly visualized using near-field microscopy coupled with heterodyne interferometric detection. The experimental results were analyzed and found to match very well with theoretical prediction from numerical simulations thereby validating the design principles and our implementation. Plasmonic nanostructures could be engineered to exhibit unique optical properties such as Fano resonance characterized by narrow asymmetrical lineshape. We present dynamic tuning and symmetry lowering of Fano resonances in plasmonic nanostructures fabricated on flexible substrates. The tuning of Fano resonance was achieved by application of uniaxial mechanical stress. The design of the nanostructures was facilitated by extensive numerical simulations and the symmetry lowering was analyzed using group theoretical methods. The nanostructures were fabricated using electron beam lithography and optically characterized for various mechanical stress. The experimental results were in good

  11. Engineering students' experiences and perceptions of workplace problem solving

    NASA Astrophysics Data System (ADS)

    Pan, Rui

    In this study, I interviewed 22 engineering Co-Op students about their workplace problem solving experiences and reflections and explored: 1) Of Co-Op students who experienced workplace problem solving, what are the different ways in which students experience workplace problem solving? 2) How do students perceive a) the differences between workplace problem solving and classroom problem solving and b) in what areas are they prepared by their college education to solve workplace problems? To answer my first research question, I analyzed data through the lens of phenomenography and I conducted thematic analysis to answer my second research question. The results of this study have implications for engineering education and engineering practice. Specifically, the results reveal the different ways students experience workplace problem solving, which provide engineering educators and practicing engineers a better understanding of the nature of workplace engineering. In addition, the results indicate that there is still a gap between classroom engineering and workplace engineering. For engineering educators who aspire to prepare students to be future engineers, it is imperative to design problem solving experiences that can better prepare students with workplace competency.

  12. Socialization experiences resulting from engineering teaching assistantships at Purdue University

    NASA Astrophysics Data System (ADS)

    Mena, Irene B.

    The purpose of this study was to explore and understand the types of socialization experiences that result from engineering teaching assistantships. Using situated learning as the theoretical framework and phenomenology as the methodological framework, this study highlights the experiences of 28 engineering doctoral students who worked as engineering teaching assistants (TAs), in response to the following research question: What socialization experiences do engineering doctoral students report going through as a result of being engineering TAs? Data was obtained via interviews (individual and focus group, with participants from various schools of engineering at Purdue University), informal observations, and supporting documents. These multiple data sources were analyzed and triangulated to find recurring themes in and characteristics of the graduate engineering TA experience. Participants in this study characterized their socialization experiences in the following categories: participation in TA training of different kinds, interactions with different groups of individuals, the undertaking of various types of TA responsibilities, the balancing of teaching and research, and the use and development of certain skills. In addition, some differences in experiences were found depending on type of TA appointment, stage of doctoral study, semesters as a TA, career goals, and engineering program.

  13. Genetic Engineering of Optical Properties of Biomaterials

    NASA Astrophysics Data System (ADS)

    Gourley, Paul; Naviaux, Robert; Yaffe, Michael

    2008-03-01

    Baker's yeast cells are easily cultured and can be manipulated genetically to produce large numbers of bioparticles (cells and mitochondria) with controllable size and optical properties. We have recently employed nanolaser spectroscopy to study the refractive index of individual cells and isolated mitochondria from two mutant strains. Results show that biomolecular changes induced by mutation can produce bioparticles with radical changes in refractive index. Wild-type mitochondria exhibit a distribution with a well-defined mean and small variance. In striking contrast, mitochondria from one mutant strain produced a histogram that is highly collapsed with a ten-fold decrease in the mean and standard deviation. In a second mutant strain we observed an opposite effect with the mean nearly unchanged but the variance increased nearly a thousand-fold. Both histograms could be self-consistently modeled with a single, log-normal distribution. The strains were further examined by 2-dimensional gel electrophoresis to measure changes in protein composition. All of these data show that genetic manipulation of cells represents a new approach to engineering optical properties of bioparticles.

  14. Aircraft Turbine Engine Monitoring Experience: Implications for the F100 Engine Diagnostic System Program

    DTIC Science & Technology

    1979-04-01

    malfunction re- port data were obtained from the Program Office. -8- EHMS (T-38 / J85 ) ACTIVITY OUTCOMES JULY 76 - MAY 77 INSTRUMENTED ENGINES CONTROL...interesting to note that the J85 was a mature engine and that the number of engine problems encountered was not very great. Also, the EHMS was not a new...copyright notation hereon. Library of Congress Cataloging In PObNiation Data Birkier, John L Aircraft turbine engine monitoring experience. ([Report

  15. Experiment-Based Teaching in Advanced Control Engineering

    ERIC Educational Resources Information Center

    Precup, R.-E.; Preitl, S.; Radac, M.-B.; Petriu, E. M.; Dragos, C.-A.; Tar, J. K.

    2011-01-01

    This paper discusses an experiment-based approach to teaching an advanced control engineering syllabus involving controlled plant analysis and modeling, control structures and algorithms, real-time laboratory experiments, and their assessment. These experiments are structured around the representative case of the longitudinal slip control of an…

  16. Building a Framework for Engineering Design Experiences in High School

    ERIC Educational Resources Information Center

    Denson, Cameron D.; Lammi, Matthew

    2014-01-01

    In this article, Denson and Lammi put forth a conceptual framework that will help promote the successful infusion of engineering design experiences into high school settings. When considering a conceptual framework of engineering design in high school settings, it is important to consider the complex issue at hand. For the purposes of this…

  17. Labor Market Experience for Engineers During Periods of Changing Demand.

    ERIC Educational Resources Information Center

    Bain, Trevor

    This report was prepared to present reviews, synthesis, and evaluation of research studies and demonstration projects concerned with the labor market experience of unemployed engineers, particularly in aerospace-defense. It also includes a review and evaluation of national manpower efforts to aid the reemployment of unemployed engineers,…

  18. Rutgers University Research Experience for Teachers in Engineering: Preliminary Findings

    ERIC Educational Resources Information Center

    Laffey, Evelyn H.; Cook-Chennault, Kimberly; Hirsch, Linda S.

    2013-01-01

    In addressing the nation's need for a more technologically-literate society, the Rutgers University Research Experience for Teachers in Engineering (RU RET-E) is designed to: (1) engage middle and high school math and science teachers in innovative "green" engineering research during the summer, and (2) support teachers in integrating…

  19. Pathways to Engineering: The Validation Experiences of Transfer Students

    ERIC Educational Resources Information Center

    Zhang, Yi; Ozuna, Taryn

    2015-01-01

    Community college engineering transfer students are a critical student population of engineering degree recipients and technical workforce in the United States. Focusing on this group of students, we adopted Rendón's (1994) validation theory to explore the students' experiences in community colleges prior to transferring to a four-year…

  20. Women Engineering Transfer Students: The Community College Experience

    ERIC Educational Resources Information Center

    Patterson, Susan J.

    2011-01-01

    An interpretative philosophical framework was applied to a case study to document the particular experiences and perspectives of ten women engineering transfer students who once attended a community college and are currently enrolled in one of two university professional engineering programs. This study is important because women still do not earn…

  1. Property-Based Software Engineering Measurement

    NASA Technical Reports Server (NTRS)

    Briand, Lionel; Morasca, Sandro; Basili, Victor R.

    1995-01-01

    Little theory exists in the field of software system measurement. Concepts such as complexity, coupling, cohesion or even size are very often subject to interpretation and appear to have inconsistent definitions in the literature. As a consequence, there is little guidance provided to the analyst attempting to define proper measures for specific problems. Many controversies in the literature are simply misunderstandings and stem from the fact that some people talk about different measurement concepts under the same label (complexity is the most common case). There is a need to define unambiguously the most important measurement concepts used in the measurement of software products. One way of doing so is to define precisely what mathematical properties characterize these concepts regardless of the specific software artifacts to which these concepts are applied. Such a mathematical framework could generate a consensus in the software engineering community and provide a means for better communication among researchers, better guidelines for analysis, and better evaluation methods for commercial static analyzers for practitioners. In this paper, we propose a mathematical framework which is generic, because it is not specific to any particular software artifact, and rigorous, because it is based on precise mathematical concepts. This framework defines several important measurement concepts (size, length, complexity, cohesion, coupling). It is not intended to be complete or fully objective; other frameworks could have been proposed and different choices could have been made. However, we believe that the formalism and properties we introduce are convenient and intuitive. In addition, we have reviewed the literature on this subject and compared it with our work. This framework contributes constructively to a firmer theoretical ground of software measurement.

  2. Property-Based Software Engineering Measurement

    NASA Technical Reports Server (NTRS)

    Briand, Lionel C.; Morasca, Sandro; Basili, Victor R.

    1997-01-01

    Little theory exists in the field of software system measurement. Concepts such as complexity, coupling, cohesion or even size are very often subject to interpretation and appear to have inconsistent definitions in the literature. As a consequence, there is little guidance provided to the analyst attempting to define proper measures for specific problems. Many controversies in the literature are simply misunderstandings and stem from the fact that some people talk about different measurement concepts under the same label (complexity is the most common case). There is a need to define unambiguously the most important measurement concepts used in the measurement of software products. One way of doing so is to define precisely what mathematical properties characterize these concepts, regardless of the specific software artifacts to which these concepts are applied. Such a mathematical framework could generate a consensus in the software engineering community and provide a means for better communication among researchers, better guidelines for analysts, and better evaluation methods for commercial static analyzers for practitioners. In this paper, we propose a mathematical framework which is generic, because it is not specific to any particular software artifact and rigorous, because it is based on precise mathematical concepts. We use this framework to propose definitions of several important measurement concepts (size, length, complexity, cohesion, coupling). It does not intend to be complete or fully objective; other frameworks could have been proposed and different choices could have been made. However, we believe that the formalisms and properties we introduce are convenient and intuitive. This framework contributes constructively to a firmer theoretical ground of software measurement.

  3. Clinical Engineering: Experiences of assisted professional practices

    NASA Astrophysics Data System (ADS)

    Langone, Luis; Vanetta, Marcos; Vazquez, Marcelo; Rotger, Viviana; Olivera, Juan Manuel

    2007-11-01

    In the curricula of the Biomedical Engineering career of the Facultad de Ciencias Exactas y Tecnología of the Universidad Nacional de Tucumán, Argenitna, there are the Assisted Professional Practices. Within this framework, the students have the possibility of performing practices in the clinic Sanatorio 9 de Julio. One of the objectives of these practices is to apply the concepts, methods and procedures studied along the career in the field work under real work conditions. From the point of view of the host institution, the objective is to improve the performance of the different services and areas applying the tools of Biomedical Engineering. The present work shows an example of such practices where an equipment preliminary analysis was made, its use and maintenance corresponding to the surgical unit of the clinic.

  4. Interactive Approach on Experiments in Mechanical Engineering : Vibration

    NASA Astrophysics Data System (ADS)

    Kumon, Makoto; Torigoe, Ippei; Mizumoto, Ikuro; Yamaguchi, Teruo; Kohzawa, Ryuichi; Ohshima, Yasutaka

    Experiments in the engineering education play important roles in motivating students to study voluntarily. A trial aiming to enhance this effect in the experiment of vibration at Mechanical System Engineering, Kumamoto University is introduced. The trial consists of 1) oral presentation by students, 2) web-based learning system and 3) feedback through reports. An evaluation by questionnaire was conducted to show the validity of this trial. This result revealed that the trial succeeded to encourage students.

  5. Developing Conceptual Hypersonic Airbreathing Engines Using Design of Experiments Methods

    NASA Technical Reports Server (NTRS)

    Ferlemann, Shelly M.; Robinson, Jeffrey S.; Martin, John G.; Leonard, Charles P.; Taylor, Lawrence W.; Kamhawi, Hilmi

    2000-01-01

    Designing a hypersonic vehicle is a complicated process due to the multi-disciplinary synergy that is required. The greatest challenge involves propulsion-airframe integration. In the past, a two-dimensional flowpath was generated based on the engine performance required for a proposed mission. A three-dimensional CAD geometry was produced from the two-dimensional flowpath for aerodynamic analysis, structural design, and packaging. The aerodynamics, engine performance, and mass properties arc inputs to the vehicle performance tool to determine if the mission goals were met. If the mission goals were not met, then a flowpath and vehicle redesign would begin. This design process might have to be performed several times to produce a "closed" vehicle. This paper will describe an attempt to design a hypersonic cruise vehicle propulsion flowpath using a Design of' Experiments method to reduce the resources necessary to produce a conceptual design with fewer iterations of the design cycle. These methods also allow for more flexible mission analysis and incorporation of additional design constraints at any point. A design system was developed using an object-based software package that would quickly generate each flowpath in the study given the values of the geometric independent variables. These flowpath geometries were put into a hypersonic propulsion code and the engine performance was generated. The propulsion results were loaded into statistical software to produce regression equations that were combined with an aerodynamic database to optimize the flowpath at the vehicle performance level. For this example, the design process was executed twice. The first pass was a cursory look at the independent variables selected to determine which variables are the most important and to test all of the inputs to the optimization process. The second cycle is a more in-depth study with more cases and higher order equations representing the design space.

  6. Mechanical properties of natural cartilage and tissue-engineered constructs.

    PubMed

    Little, Christopher James; Bawolin, Nahshon Kenneth; Chen, Xiongbiao

    2011-08-01

    There has been much research over the past two decades with the aim of engineering cartilage constructs for repairing or restoring damaged cartilage. To engineer healthy neocartilage, the constructs must have mechanical properties matching those of native cartilage as well as appropriate for the loading conditions of the joint. This article discusses the mechanical behavior of native cartilage and surveys different types of tensile, compressive, and shear tests with their limitations. It also comprehensively reviews recent work and achievements in developing the mathematical models representing the mechanical properties of both native and engineered cartilage. Different methods for enhancing the mechanical properties of engineered cartilage are also discussed, including scaffold design, mechanical stimulation, and chemical stimulation. This article concludes with recommendations for future research aimed at achieving engineered cartilage with mechanical properties matching those found in native cartilage.

  7. A Study of Experience Credit for Professional Engineering Licensure

    SciTech Connect

    Martin, M.A.

    2003-08-11

    Oak Ridge National Laboratory performed a study of experience credit for professional engineering licensure for the Department of Energy's Industrial Assessment Center (IAC) Program. One of the study's goals was to determine how state licensure boards grant experience credit for engineering licensure, particularly in regards to IAC experience and experience prior to graduation. Another goal involved passing IAC information to state licensure boards to allow the boards to become familiar with the program and determine if they would grant credit to IAC graduates. The National Council of Examiners for Engineers and Surveyors (NCEES) has adopted a document, the ''Model Law''. This document empowers states to create state engineering boards and oversee engineering licensure. The board can also interpret and adopt rules and regulations. The Model Law also gives a general ''process'' for engineering licensure, the ''Model Law Engineer''. The Model Law Engineer requires that an applicant for professional licensure, or professional engineering (PE) licensure, obtain a combination of formal education and professional experience and successfully complete the fundamentals of engineering (FE) and PE exams. The Model Law states that a PE applicant must obtain four years of ''acceptable'' engineering experience after graduation to be allowed to sit for the PE exam. Although the Model Law defines ''acceptable experience,'' it is somewhat open to interpretation, and state boards decide whether applicants have accumulated the necessary amount of experience. The Model Law also allows applicants one year of credit for postgraduate degrees as well as experience credit for teaching courses in engineering. The Model Law grants states the power to adopt and amend the bylaws and rules of the Model Law licensure process. It allows state boards the freedom to modify the experience requirements for professional licensure. This power has created variety in experience requirements, and

  8. Engineering teacher training models and experiences

    NASA Astrophysics Data System (ADS)

    González-Tirados, R. M.

    2009-04-01

    Institutions and Organisations that take training seriously and devote time, effort and resources, etc, to their own teams are more likely to succeed, since both initial teacher training and continuous improvement, studies, hours of group discussion, works on innovation and educational research, talks and permanent meetings, etc, will all serve to enhance teaching and its quality. Teachers will be able to introduce new components from previously taught classes into their university teaching which will contribute to improving their work and developing a suitable academic environment to include shared objectives, teachers and students. Moreover, this training will serve to enhance pedagogic innovation, new teaching-learning methodologies and contribute to getting teaching staff involved in respect of the guidelines set out by the EHEA. Bearing in mind that training and motivation can be key factors in any teacher's "performance", their productivity and the quality of their teaching, Teacher Training for a specific post inside the University Organisation is standard practice of so-called Human Resources management and an integral part of a teacher's work; it is a way of professionalising the teaching of the different branches of Engineering. At Madrid Polytechnic University, in the Institute of Educational Sciences (ICE), since it was founded in 1972, we have been working hard with university teaching staff. But it was not until 1992 after carrying out various studies on training needs that we planned and programmed different training actions, offering a wide range of possibilities. Thus, we designed and taught an "Initial Teacher Training Course", as it was first called in 1992, a programme basically aimed to train young Engineering teachers just setting out on their teaching career. In 2006, the name was changed to "Advanced University Teacher Training Course". Subsequently, with the appearance of the Bologna Declaration and the creation of the European Higher

  9. Textile Processes for Engineering Tissues with Biomimetic Architectures and Properties.

    PubMed

    Fallahi, Afsoon; Khademhosseini, Ali; Tamayol, Ali

    2016-09-01

    Textile technologies in which fibers containing biological factors and cells are formed and assembled into constructs with biomimetic properties have attracted significant attention in the field of tissue engineering. This Forum article highlights the most prominent advances of the field in the areas of fiber fabrication and construct engineering.

  10. Undergraduate engineering students' experiences of interdisciplinary learning: a phenomenographic perspective

    NASA Astrophysics Data System (ADS)

    Hsu, Ming-Chien

    Engineers are expected to work with people with different disciplinary knowledge to solve real-world problems that are inherently complex, which is one of the reasons that interdisciplinary learning has become a common pedagogical practice in engineering education. However, empirical evidence on the impact of interdisciplinary learning on undergraduates is lacking. Regardless of the differences in the scope of methods used to assess interdisciplinary learning, frameworks of interdisciplinary learning are imperative for developing attainable outcomes as well as interpreting assessment data. Existing models of interdisciplinary learning have been either conceptual or based on research faculty members' experiences rather than empirical data. The study addressed the gap by exploring the different ways that undergraduate engineering students experience interdisciplinary learning. A phenomenographic methodological framework was used to guide the design, data collection, and data analysis of the study. Twenty-two undergraduate engineering students with various interdisciplinary learning experiences were interviewed using semi-structured protocols. They concretely described their experiences and reflected meaning associated with those experiences. Analysis of the data revealed eight qualitatively different ways that students experience interdisciplinary learning, which include: interdisciplinary learning as (A) no awareness of differences, (B) control and assertion, (C) coping with differences, (D) navigating creative differences, (E) learning from differences, (F) bridging differences, (G) expanding intellectual boundaries, and (H) commitment to holistic perspectives. Categories D through H represent a hierarchical structure of increasingly comprehensive way of experiencing interdisciplinary learning. Further analysis uncovered two themes that varied throughout the categories: (i) engagement with differences and (ii) purpose and integration. Students whose experiences lie

  11. Studies and experiments in the Software Engineering Lab (SEL)

    NASA Technical Reports Server (NTRS)

    Mcgarry, F. E.; Card, D. N.

    1985-01-01

    The Software Engineering Laboratory (SEL) is an organization created nearly 10 years ago for the purpose of identifying, measuring and applying quality software engineering techniques in a production environment. The members of the SEL include NASA/Goddard Space Flight Center (GSFC, the sponsor and organizer), University of Maryland, and Computer Sciences Corporation. Since its inception the SEL has conducted numerous experiments, and has evaluated a wide range of software technologies. This paper describes several of the more recent experiments as well as some of the general conclusions to which the SEL has arrived.

  12. Structure-property relations in engineered semiconductor nanomaterials (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Hollingsworth, Jennifer A.; Htoon, Han

    2016-09-01

    Particle-size or `quantum-confinement' effects have been used for decades to tune semiconductor opto-electronic properties. More recently, particle size control as the primary means for properties control has been succeeded by nanoscale hetero-structuring. In this case, the nanosized particle is modified to include internal, nanoscale interfaces, generally defined by compositional variations that induce additional changes to semiconductor properties. These changes can entail enhancements to the size-induced properties as well as unexpected or `emergent' behaviors. Common structural motifs include enveloping a spherical semiconductor nanocrystal, i.e., a quantum dot, within a shell of a different composition. In this talk, I will discuss how solution-phase synthesis can be used to create these structures with precisely `engineered' complexity. Most notably, I will review our experiences with so-called `giant' quantum dots that, due to their internal nanoscale structure, exhibit a range of novel behaviors, including being non-blinking and non-photobleaching (Chen et al. J. Am. Chem. Soc. 2008, 130, 5026; Ghosh et al. J. Am. Chem. Soc. 2012, 134, 9634; Dennis et al. Nano Lett. 2012 12, 5545; Acharya et al. J. Am. Chem. Soc. 2015, 137, 3755), and remarkably efficient emitters of `multi-excitons' due to extreme suppression of Auger recombination (Mangum et al. Nanoscale 2014, 6, 3712; Gao et al. Adv. Optical Mater. 2015, 3, 39). I will discuss recent work extending non-blinking behavior to the blue/green and "dual-color" emission, and show how correlated optical/structural characterization can reveal new information regarding structure-property relations to guide new nanomaterials development (Orfield et al. ACS Nano, Article ASAP).

  13. Global engineering education programs: More than just international experiences

    NASA Astrophysics Data System (ADS)

    McNeill, Nathan J.

    Engineers in both industry and academia recognize the global nature of the profession. This has lead to calls for engineering students to develop knowledge, skills, and attitudes necessary for success within a global profession. Many institutions are developing globally oriented programs specifically for their engineering students and are eager to know if these programs are helping their students to develop attributes that meet their program objectives, accreditation requirements, and the needs and desires of prospective employers. Administrators of such programs currently lack research data to support the learning objectives they are setting for their programs. This study documented the individual experiences and learning outcomes of students involved in three global education programs for engineering students. The first program provided a portfolio of experiences including foreign language instruction, one semester of study abroad, internships in the U.S. and abroad, and a two-semester global team design project. The second program was a one semester study abroad program in China, and the third was a global service project whose purpose was to design an irrigation system for two small farms in Rwanda. The research questions guiding this study were: 1. What specific knowledge, skills, and attitudes are students gaining from participation in their respective global engineering programs? 2. What kinds of experiences are resulting in these learning outcomes? Interviews were used to elicit the experiences and learning outcomes of participants in this study. Program administrators were also interviewed for their perspectives on the experiences and learning outcomes of participants for the purpose of triangulation. The study identified more than 50 outcomes that resulted from students' experiences in these three programs. The most prevalent outcomes across all three programs included knowledge of culture, openness to new experiences and other cultures, and communication

  14. Space Station Freedom as an engineering experiment station: An overview

    NASA Technical Reports Server (NTRS)

    Rose, M. Frank

    1992-01-01

    In this presentation, the premise that Space Station Freedom has great utility as an engineering experiment station will be explored. There are several modes in which it can be used for this purpose. The most obvious are space qualification, process development, in space satellite repair, and materials engineering. The range of engineering experiments which can be done at Space Station Freedom run the gamut from small process oriented experiments to full exploratory development models. A sampling of typical engineering experiments are discussed in this session. First and foremost, Space Station Freedom is an elaborate experiment itself, which, if properly instrumented, will provide engineering guidelines for even larger structures which must surely be built if humankind is truly 'outward bound.' Secondly, there is the test, evaluation and space qualification of advanced electric thruster concepts, advanced power technology and protective coatings which must of necessity be tested in the vacuum of space. The current approach to testing these technologies is to do exhaustive laboratory simulation followed by shuttle or unmanned flights. Third, the advanced development models of life support systems intended for future space stations, manned mars missions, and lunar colonies can be tested for operation in a low gravity environment. Fourth, it will be necessary to develop new protective coatings, establish construction techniques, evaluate new materials to be used in the upgrading and repair of Space Station Freedom. Finally, the industrial sector, if it is ever to build facilities for the production of commercial products, must have all the engineering aspects of the process evaluated in space prior to a commitment to such a facility.

  15. 'Food for Engineers': Intellectual Property Education for Innovators

    ERIC Educational Resources Information Center

    Soetendorp, Ruth

    2004-01-01

    Intellectual property competence can assist individuals and organizations to capitalize on opportunities presented by accelerating developments in the knowledge economy. Engineers translate ideas into concrete solutions, which are frequently useful and commercially valuable, if the intrinsic intellectual property has been identified and protected.…

  16. Micro-CT-based screening of biomechanical and structural properties of bone tissue engineering scaffolds.

    PubMed

    Van Cleynenbreugel, Tim; Schrooten, Jan; Van Oosterwyck, Hans; Vander Sloten, Jos

    2006-07-01

    The development of successful scaffolds for bone tissue engineering requires a concurrent engineering approach that combines different research fields. In order to limit in vivo experiments and reduce trial and error research, a scaffold screening technique has been developed. In this protocol seven structural and three biomechanical properties of potential scaffold materials are quantified and compared to the desired values. The property assessment is done on computer models of the scaffolds, and these models are based on micro-CT images. As a proof of principle, three porous scaffolds were evaluated with this protocol: stainless steel, hydroxyapatite, and titanium. These examples demonstrate that the modelling technique is able to quantify important scaffold properties. Thus, a powerful technique for automated screening of bone tissue engineering scaffolds has been developed that in a later stage may be used to tailor the scaffold properties to specific requirements.

  17. Women's Experiences in the Engineering Laboratory in Japan

    ERIC Educational Resources Information Center

    Hosaka, Masako

    2014-01-01

    This qualitative study aims to examine Japanese women undergraduate engineering students' experiences of interacting with departmental peers of the same year in the laboratory setting by using interview data of 32 final-year students at two modestly selective national universities in Japan. Expectation state theory that explains unequal…

  18. Learning English: Experiences and Needs of Saudi Engineering Students

    ERIC Educational Resources Information Center

    Unruh, Susan; Obeidat, Fayiz

    2015-01-01

    In this qualitative study, Saudi engineering students talk openly of their experiences learning English in the Kingdom of Saudi Arabia (KSA) and as university students in the United States (US). These students reported that they learned only the basics of vocabulary and grammar in KSA. Consequently, they came to the US with few English skills. In…

  19. Creating meaningful learning experiences: Understanding students' perspectives of engineering design

    NASA Astrophysics Data System (ADS)

    Aleong, Richard James Chung Mun

    , relevance, and transfer. With this framework of student learning, engineering educators can enhance learning experiences by engaging all three levels of students' understanding. The curriculum studies orientation applied the three holistic elements of curriculum---subject matter, society, and the individual---to conceptualize design considerations for engineering curriculum and teaching practice. This research supports the characterization of students' learning experiences to help educators and students optimize their teaching and learning of design education.

  20. Digoxin and Adenosine Triphosphate Enhance the Functional Properties of Tissue-Engineered Cartilage

    PubMed Central

    Makris, Eleftherios A.; Huang, Brian J.; Hu, Jerry C.; Chen-Izu, Ye

    2015-01-01

    Toward developing engineered cartilage for the treatment of cartilage defects, achieving relevant functional properties before implantation remains a significant challenge. Various chemical and mechanical stimuli have been used to enhance the functional properties of engineered musculoskeletal tissues. Recently, Ca2+-modulating agents have been used to enhance matrix synthesis and biomechanical properties of engineered cartilage. The objective of this study was to determine whether other known Ca2+ modulators, digoxin and adenosine triphosphate (ATP), can be employed as novel stimuli to increase collagen synthesis and functional properties of engineered cartilage. Neocartilage constructs were formed by scaffold-free self-assembling of primary bovine articular chondrocytes. Digoxin, ATP, or both agents were added to the culture medium for 1 h/day on days 10–14. After 4 weeks of culture, neocartilage properties were assessed for gross morphology, biochemical composition, and biomechanical properties. Digoxin and ATP were found to increase neocartilage collagen content by 52–110% over untreated controls, while maintaining proteoglycan content near native tissue values. Furthermore, digoxin and ATP increased the tensile modulus by 280% and 180%, respectively, while the application of both agents increased the modulus by 380%. The trends in tensile properties were found to correlate with the amount of collagen cross-linking. Live Ca2+ imaging experiments revealed that both digoxin and ATP were able to increase Ca2+ oscillations in monolayer-cultured chondrocytes. This study provides a novel approach toward directing neocartilage maturation and enhancing its functional properties using novel Ca2+ modulators. PMID:25473799

  1. Digoxin and adenosine triphosphate enhance the functional properties of tissue-engineered cartilage.

    PubMed

    Makris, Eleftherios A; Huang, Brian J; Hu, Jerry C; Chen-Izu, Ye; Athanasiou, Kyriacos A

    2015-03-01

    Toward developing engineered cartilage for the treatment of cartilage defects, achieving relevant functional properties before implantation remains a significant challenge. Various chemical and mechanical stimuli have been used to enhance the functional properties of engineered musculoskeletal tissues. Recently, Ca(2+)-modulating agents have been used to enhance matrix synthesis and biomechanical properties of engineered cartilage. The objective of this study was to determine whether other known Ca(2+) modulators, digoxin and adenosine triphosphate (ATP), can be employed as novel stimuli to increase collagen synthesis and functional properties of engineered cartilage. Neocartilage constructs were formed by scaffold-free self-assembling of primary bovine articular chondrocytes. Digoxin, ATP, or both agents were added to the culture medium for 1 h/day on days 10-14. After 4 weeks of culture, neocartilage properties were assessed for gross morphology, biochemical composition, and biomechanical properties. Digoxin and ATP were found to increase neocartilage collagen content by 52-110% over untreated controls, while maintaining proteoglycan content near native tissue values. Furthermore, digoxin and ATP increased the tensile modulus by 280% and 180%, respectively, while the application of both agents increased the modulus by 380%. The trends in tensile properties were found to correlate with the amount of collagen cross-linking. Live Ca(2+) imaging experiments revealed that both digoxin and ATP were able to increase Ca(2+) oscillations in monolayer-cultured chondrocytes. This study provides a novel approach toward directing neocartilage maturation and enhancing its functional properties using novel Ca(2+) modulators.

  2. Virtual parameter-estimation experiments in Bioprocess-Engineering education.

    PubMed

    Sessink, Olivier D T; Beeftink, Hendrik H; Hartog, Rob J M; Tramper, Johannes

    2006-05-01

    Cell growth kinetics and reactor concepts constitute essential knowledge for Bioprocess-Engineering students. Traditional learning of these concepts is supported by lectures, tutorials, and practicals: ICT offers opportunities for improvement. A virtual-experiment environment was developed that supports both model-related and experimenting-related learning objectives. Students have to design experiments to estimate model parameters: they choose initial conditions and 'measure' output variables. The results contain experimental error, which is an important constraint for experimental design. Students learn from these results and use the new knowledge to re-design their experiment. Within a couple of hours, students design and run many experiments that would take weeks in reality. Usage was evaluated in two courses with questionnaires and in the final exam. The faculties involved in the two courses are convinced that the experiment environment supports essential learning objectives well.

  3. Exploring the Engineering Student Experience: Findings from the Academic Pathways of People Learning Engineering Survey (APPLES). TR-10-01

    ERIC Educational Resources Information Center

    Sheppard, Sheri; Gilmartin, Shannon; Chen, Helen L.; Donaldson, Krista; Lichtenstein, Gary; Eris, Ozgur; Lande, Micah; Toye, George

    2010-01-01

    This report is based on data from the Academic Pathways of People Learning Engineering Survey (APPLES), administered to engineering students at 21 U.S. engineering colleges and schools in the spring of 2008. The first comprehensive set of analyses completed on the APPLES dataset presented here looks at how engineering students experience their…

  4. Immunosuppressive and anti-inflammatory properties of engineered nanomaterials.

    PubMed

    Ilinskaya, A N; Dobrovolskaia, M A

    2014-09-01

    Nanoparticle interactions with various components of the immune system are determined by their physicochemical properties such as size, charge, hydrophobicity and shape. Nanoparticles can be engineered to either specifically target the immune system or to avoid immune recognition. Nevertheless, identifying their unintended impacts on the immune system and understanding the mechanisms of such accidental effects are essential for establishing a nanoparticle's safety profile. While immunostimulatory properties have been reviewed before, little attention in the literature has been given to immunosuppressive and anti-inflammatory properties. The purpose of this review is to fill this gap. We will discuss intended immunosuppression achieved by either nanoparticle engineering, or the use of nanoparticles to carry immunosuppressive or anti-inflammatory drugs. We will also review unintended immunosuppressive properties of nanoparticles per se and consider how such properties could be either beneficial or adverse.

  5. Apollo experience report: Guidance and control systems. Engineering simulation program

    NASA Technical Reports Server (NTRS)

    Gilbert, D. W.

    1973-01-01

    The Apollo Program experience from early 1962 to July 1969 with respect to the engineering-simulation support and the problems encountered is summarized in this report. Engineering simulation in support of the Apollo guidance and control system is discussed in terms of design analysis and verification, certification of hardware in closed-loop operation, verification of hardware/software compatibility, and verification of both software and procedures for each mission. The magnitude, time, and cost of the engineering simulations are described with respect to hardware availability, NASA and contractor facilities (for verification of the command module, the lunar module, and the primary guidance, navigation, and control system), and scheduling and planning considerations. Recommendations are made regarding implementation of similar, large-scale simulations for future programs.

  6. Women's experiences in the engineering laboratory in Japan

    NASA Astrophysics Data System (ADS)

    Hosaka, Masako

    2014-07-01

    This qualitative study aims to examine Japanese women undergraduate engineering students' experiences of interacting with departmental peers of the same year in the laboratory setting by using interview data of 32 final-year students at two modestly selective national universities in Japan. Expectation state theory that explains unequal relationship between men and women is used as a framework. Findings suggest that women generally had a discouraging experience while working with their male peers. Specifically, women participated less and lost confidence by comparing with the men who appeared to be confident and competent.

  7. Engineering Property Prediction Tools for Tailored Polymer Composite Structures

    SciTech Connect

    Nguyen, Ba Nghiep; Foss, Peter; Wyzgoski, Michael; Trantina, Gerry; Kunc, Vlastimil; Schutte, Carol; Smith, Mark T.

    2009-12-23

    This report summarizes our FY 2009 research activities for the project titled:"Engineering Property Prediction Tools for Tailored Polymer Composite Structures." These activities include (i) the completion of the development of a fiber length attrition model for injection-molded long-fiber thermoplastics (LFTs), (ii) development of the a fatigue damage model for LFTs and its implementation in ABAQUS, (iii) development of an impact damage model for LFTs and its implementation in ABAQUS, (iv) development of characterization methods for fatigue testing, (v) characterization of creep and fatigue responses of glass-fiber/polyamide (PA6,6) and glass-fiber/polypropylene (PP), (vi) characterization of fiber length distribution along the flow length of glass/PA6,6 and glass-fiber/PP, and (vii) characterization of impact responses of glass-fiber/PA6,6. The fiber length attrition model accurately captures the fiber length distribution along the flow length of the studied glass-fiber/PP material. The fatigue damage model is able to predict the S-N and stiffness reduction data which are valuable to the fatigue design of LFTs. The impact damage model correctly captures damage accumulation observed in experiments of glass-fiber/PA6,6 plaques.Further work includes validations of these models for representative LFT materials and a complex LFT part.

  8. Optical properties monitor: Experiment definition phase

    NASA Technical Reports Server (NTRS)

    Wilkes, Donald R.; Bennett, Jean M.; Hummer, Leigh L.; Chipman, Russell A.; Hadaway, James B.; Pezzaniti, Larry

    1990-01-01

    The stability of materials used in the space environment will continue to be a limiting technology for space missions. The Optical Properties Monitor (OPM) Experiment provides a comprehensive space research program to study the effects of the space environment (both natural and induced) on optical, thermal and space power materials. The OPM Experiment was selected for definition under the NASA/OAST In-Space Technology Experiment Program. The results of the OPM Definition Phase are presented. The OPM experiment will expose selected materials to the space environment and measure the effects with in-space optical measurements. In-space measurements include total hemispherical reflectance total integrated scatter and VUV reflectance/transmittance. The in-space measurements will be augmented with extensive pre- and post-flight sample measurements to determine other optical, mechanical, electrical, chemical or surface effects of space exposure. Environmental monitors will provide the amount and time history of the sample exposure to solar irradiation, atomic oxygen and molecular contamination.

  9. Optical properties monitor: Experiment definition phase

    NASA Technical Reports Server (NTRS)

    Wilkes, Donald R.; Bennett, Jean M.; Hummer, Leigh L.; Chipman, Russell A.; Hadaway, James B.; Pezzaniti, Larry

    1989-01-01

    The stability of materials used in the space environment will continue to be a limiting technology for space missions. The Optical Properties Monitor (OPM) Experiment provides a comprehensive space research program to study the effects of the space environment-both natural and induced-on optical, thermal and space power materials. The OPM Experiment was selected for definition under the NASA/OAST In-Space Technology Experiment Program. The results of the OPM Definition Phase are presented. The OPM Experiment will expose selected materials to the space environment and measure the effects with in-space optical measurements. In-space measurements include total hemispherical reflectance total integrated scatter and VUV reflectance/transmittance. The in-space measurements will be augmented with extensive pre- and post-flight sample measurements to determine other optical, mechanical, electrical, chemical or surface effects of space exposure. Environmental monitors will provide the amount and time history of the sample exposure to solar irradiation, atomic oxygen and molecular contamination.

  10. Experiments on Plume Spreading by Engineered Injection and Extraction

    NASA Astrophysics Data System (ADS)

    Mays, D. C.; Jones, M.; Tigera, R. G.; Neupauer, R.

    2014-12-01

    The notion that groundwater remediation is transport-limited emphasizes the coupling between physical (i.e., hydrodynamic), geochemical, and microbiological processes in the subsurface. Here we leverage this coupling to promote groundwater remediation using the approach of engineered injection and extraction. In this approach, inspired by the literature on chaotic advection, uncontaminated groundwater is injected and extracted through a manifold of wells surrounding the contaminated plume. The potential of this approach lies in its ability to actively manipulate the velocity field near the contaminated plume, generating plume spreading above and beyond that resulting from aquifer heterogeneity. Plume spreading, in turn, promotes mixing and reaction by chemical and biological processes. Simulations have predicted that engineered injection and extraction generates (1) chaotic advection whose characteristics depend on aquifer heterogeneity, and (2) faster rates and increased extent of groundwater remediation. This presentation focuses on a complimentary effort to experimentally demonstrate these predictions experimentally. In preparation for future work using refractive index matched (RIM) porous media, the experiments reported here use a Hele-Shaw apparatus containing silicone oil. Engineered injection and extraction is used to manipulate the geometry of an initially circular plume of black pigment, and photographs record the plume geometry after each step of injection of extraction. Image analysis, using complimentary Eulerian and Lagrangian approaches, reveals the thickness and variability of the dispersion zone surrounding the deformed plume of black pigment. The size, shape, and evolution of this dispersion zone provides insight into the interplay between engineered injection and extraction, which generates plume structure, and dispersion (here Taylor dispersion), which destroys plume structure. These experiments lay the groundwork for application of engineered

  11. Engineering properties of Incoloy-903 and CTX-1

    NASA Technical Reports Server (NTRS)

    Ruff, P. E.

    1980-01-01

    Engineering properties of Incoloy-903 sheet and CTX-1 (high strength austentic Fe-Ni-Co alloy) bar are characterized in report. Report includes tables and plots of test data and photographs of microstructure of samples used. Two appendixes include specimen configuration and data collected from industrial survey.

  12. Collaboration for cooperative work experience programs in biomedical engineering education.

    PubMed

    Krishnan, Shankar

    2010-01-01

    Incorporating cooperative education modules as a segment of the undergraduate educational program is aimed to assist students in gaining real-life experience in the field of their choice. The cooperative work modules facilitate the students in exploring different realistic aspects of work processes in the field. The track records for cooperative learning modules are very positive. However, it is indeed a challenge for the faculty developing Biomedical Engineering (BME) curriculum to include cooperative work experience or internship requirements coupled with a heavy course load through the entire program. The objective of the present work is to develop a scheme for collaborative co-op work experience for the undergraduate training in the fast-growing BME programs. A few co-op/internship models are developed for the students pursuing undergraduate BME degree. The salient features of one co-op model are described. The results obtained support the proposed scheme. In conclusion, the cooperative work experience will be an invaluable segment in biomedical engineering education and an appropriate model has to be selected to blend with the overall training program.

  13. Learning from fellow engineering students who have current professional experience

    NASA Astrophysics Data System (ADS)

    Davies, John W.; Rutherford, Ursula

    2012-08-01

    This paper presents an investigation of how experience-led content in an engineering degree can be strengthened by creating opportunities for engineering students to benefit from the knowledge, skills and resources of students with current professional experience. Students who study civil engineering part-time at Coventry University (while also working in the industry) are being used as mentors for full-time students, and careful attention is being paid to the input they can make to group project work. This paper reviews the results of evaluations of these two initiatives. The clearest enhancement to learning provided by the part-time students in these settings is the access they provide for the full-time students to real examples and the provision of actual physical artefacts such as drawings, photos, example documents and templates. Full-time students also gain an awareness of the value of the professional skills. The study confirms the value of these initiatives and points to future improvements.

  14. Engineering education for youth: Diverse elementary school students' experiences with engineering design

    NASA Astrophysics Data System (ADS)

    Hegedus, Theresa

    Lingering concerns over the persistent achievement gap amidst the trend of an increasingly diverse society have been compounded by calls from the Oval Office, the National Science Board, and nationwide media to also address our current creativity crisis. Now, more than ever, we have a responsibility to produce a STEM-capable (science, technology, engineering, and mathematics) workforce to meet the demands of our rapidly changing local and global economic landscape. Barriers exist in our traditional educational system, which has historically limited underrepresented groups' affiliation and membership in the disciplines of science and engineering. The recent incorporation of engineering into the latest science education reform efforts presents an opportunity to expose students as early as elementary school to engineering practices and habits of mind, which have the potential to stimulate creative thinking skills through engineering design. This qualitative study was designed to examine the ways in which engineering education has the potential to promote creativity and academic competence in elementary science classrooms. As a part of my study, a diverse group of students from two fifth-grade classrooms took part in a 10-12 hour, engineering-based curriculum unit (Engineering is Elementary) during their regular science instructional time. Using a sociocultural lens, to include cultural production and identities in practice as part of my framework, I analyzed group and individual performances through classroom observations, student interviews, and teacher reflections to better understand the meaning students made of their experiences with engineering. Findings from the study included the ways in which creativity was culturally produced in the classroom to include: 1) idea generation; 2) design and innovation; 3) gumption/resourcefulness; and 4) social value. Opportunities for collaboration increased through each stage of the unit culminating with the design challenge

  15. Engineering aspects of the Stanford relativity gyro experiment

    NASA Technical Reports Server (NTRS)

    Everitt, C. W. F.; Debra, D. B.

    1981-01-01

    According to certain theoretical predictions, the Newtonian laws of motion must be corrected for the effect of a gravitational field. Schiff (1960) proposed an experiment which would demonstrate the effect predicted by Einstein's Theory of General Relativity on a gyroscope. The experiment has been under development at Stanford University since 1961. The requirements involved make it necessary that the test be performed in a satellite to take advantage of weightlessness in space. In a discussion of engineering developments related to the experiment, attention is given to the development of proportional helium thrusters, the simulation of the attitude control system, aspects of inner loop control, the mechanization of the two-loop attitude control system, the effects of helium slosh on spacecraft pointing, and the data instrumentation system.

  16. Commercial Aircraft Maintenance Experience Relating to Engine External Hardware

    NASA Technical Reports Server (NTRS)

    Soditus, Sharon M.

    2006-01-01

    Airlines are extremely sensitive to the amount of dollars spent on maintaining the external engine hardware in the field. Analysis reveals that many problems revolve around a central issue, reliability. Fuel and oil leakage due to seal failure and electrical fault messages due to wire harness failures play a major role in aircraft delays and cancellations (D&C's) and scheduled maintenance. Correcting these items on the line requires a large investment of engineering resources and manpower after the fact. The smartest and most cost effective philosophy is to build the best hardware the first time. The only way to do that is to completely understand and model the operating environment, study the field experience of similar designs and to perform extensive testing.

  17. Undergraduate engineering student experiences: Comparing sex, gender and switcher status

    NASA Astrophysics Data System (ADS)

    Fergen, Brenda Sue

    This dissertation explores undergraduate engineering experiences, comparing men with women and switchers with non-switchers. Factors related to a chilly academic climate and gender-role socialization are hypothesized to contribute to variations in men's and women's academic experiences and persistence rates. Both quantitative and qualitative data are utilized in an effort to triangulate the findings. Secondary survey data, acquired as result of a 1992 Academic Environment Survey, were utilized to test the hypothesis that sex is the most important predictor (i.e., demographic variable) of perceptions of academic climate. Regression analyses show that sex by itself is not always a significant determinant. However, when sex and college (engineering vs. other) are combined into dummy variables, they are statistically significant in models where sex was not significant alone. This finding indicates that looking at sex differences alone may be too simplistic. Thirty personal interviews were conducted with a random stratified sample of undergraduate students from the 1993 engineering cohort. The interview data indicate that differences in childhood socialization are important. With regard to persistence, differences in socialization are greater for switchers vs. non-switchers than men vs. women. Thus, gender-role socialization does not appear to play as prominent a role in women's persistence as past literature would indicate. This may be due to the self-selection process that occurs among women who choose to pursue engineering. Other aspects of childhood socialization such as parents' level of educational and occupation, students' high school academic preparation and knowledge of what to expect of college classes appear to be more important. In addition, there is evidence that, for women, male siblings play an important role in socialization. There is also evidence that women engineering students at Midwestern University face a chilly academic climate. The factors which

  18. Some engineering properties of cotton-phenolic laminates

    NASA Astrophysics Data System (ADS)

    Walsh, R. P.; Toplosky, V. J.

    2002-05-01

    Although cotton/phenolic laminates are commonly used at cryogenic temperatures as structural and insulating materials, the available low temperature materials properties data is limited. We have reviewed the existing low temperature database for cotton/phenolic and have identified areas of need. We have conducted a materials test program on the two common types (linen and canvas) of cotton/phenolic laminates to add to the existing database and to generate new data in areas where needed. Also included is a comparison of cotton/phenolic engineering properties to the properties of NEMA G-10 CR glass-cloth reinforced laminate. The properties studied here are tensile and compressive strength, elastic modulus, shear properties and thermal expansion characteristics over the temperature range from 295 K to 4 K.

  19. The Software Engineering Laboratory: An operational software experience factory

    NASA Technical Reports Server (NTRS)

    Basili, Victor R.; Caldiera, Gianluigi; Mcgarry, Frank; Pajerski, Rose; Page, Gerald; Waligora, Sharon

    1992-01-01

    For 15 years, the Software Engineering Laboratory (SEL) has been carrying out studies and experiments for the purpose of understanding, assessing, and improving software and software processes within a production software development environment at NASA/GSFC. The SEL comprises three major organizations: (1) NASA/GSFC, Flight Dynamics Division; (2) University of Maryland, Department of Computer Science; and (3) Computer Sciences Corporation, Flight Dynamics Technology Group. These organizations have jointly carried out several hundred software studies, producing hundreds of reports, papers, and documents, all of which describe some aspect of the software engineering technology that was analyzed in the flight dynamics environment at NASA. The studies range from small, controlled experiments (such as analyzing the effectiveness of code reading versus that of functional testing) to large, multiple project studies (such as assessing the impacts of Ada on a production environment). The organization's driving goal is to improve the software process continually, so that sustained improvement may be observed in the resulting products. This paper discusses the SEL as a functioning example of an operational software experience factory and summarizes the characteristics of and major lessons learned from 15 years of SEL operations.

  20. The experiences of women engineers who have completed one to five years of professional engineering employment: A phenomenological study

    NASA Astrophysics Data System (ADS)

    White, Susan M.

    Women engineers remain underrepresented in employment in engineering fields in the United States. Feminist theory views this gender disparity beyond equity in numbers for women engineers and looks at structural issues of women's access, opportunities, and quality of experience in the workplace. Research on women's success and persistence in engineering education is diverse; however, there are few studies that focus on the early years of women's careers in engineering and less using a phenomenological research design. Experiences of women engineers who have completed one to five years of professional engineering employment are presented using a phenomenological research design. Research questions explored the individual and composite experiences for the co-researchers of the study as well as challenges and advantages of the phenomenon of having completed one to five years of professional engineering employment. Themes that emanated from the data were a feeling that engineering is a positive profession, liking math and science from an early age, having experiences of attending math and science camps or learning and practicing engineering interests with their fathers for some co-researchers. Other themes included a feeling of being different as a woman in the engineering workplace, taking advantage of opportunities for training, education, and advancement to further their careers, and the role of informal and formal mentoring in developing workplace networks and engineering expertise. Co-researchers negotiated issues of management quality and support, experiences of gender discrimination in the workplace, and having to make decisions balancing their careers and family responsibilities. Finally, the women engineers for this research study expressed intentions to persist in their careers while pursuing expertise and experience in their individual engineering fields.

  1. Tissue-engineered cartilage with inducible and tunable immunomodulatory properties.

    PubMed

    Glass, Katherine A; Link, Jarrett M; Brunger, Jonathan M; Moutos, Franklin T; Gersbach, Charles A; Guilak, Farshid

    2014-07-01

    The pathogenesis of osteoarthritis is mediated in part by inflammatory cytokines including interleukin-1 (IL-1), which promote degradation of articular cartilage and prevent human mesenchymal stem cell (MSC) chondrogenesis. In this study, we combined gene therapy and functional tissue engineering to develop engineered cartilage with immunomodulatory properties that allow chondrogenesis in the presence of pathologic levels of IL-1 by inducing overexpression of IL-1 receptor antagonist (IL-1Ra) in MSCs via scaffold-mediated lentiviral gene delivery. A doxycycline-inducible vector was used to transduce MSCs in monolayer or within 3D woven PCL scaffolds to enable tunable IL-1Ra production. In the presence of IL-1, IL-1Ra-expressing engineered cartilage produced cartilage-specific extracellular matrix, while resisting IL-1-induced upregulation of matrix metalloproteinases and maintaining mechanical properties similar to native articular cartilage. The ability of functional engineered cartilage to deliver tunable anti-inflammatory cytokines to the joint may enhance the long-term success of therapies for cartilage injuries or osteoarthritis.

  2. Engineering design of the National Spherical Torus Experiment

    SciTech Connect

    C. Neumeyer; P. Heitzenroeder; J. Spitzer, J. Chrzanowski; et al

    2000-05-11

    NSTX is a proof-of-principle experiment aimed at exploring the physics of the ``spherical torus'' (ST) configuration, which is predicted to exhibit more efficient magnetic confinement than conventional large aspect ratio tokamaks, amongst other advantages. The low aspect ratio (R/a, typically 1.2--2 in ST designs compared to 4--5 in conventional tokamaks) decreases the available cross sectional area through the center of the torus for toroidal and poloidal field coil conductors, vacuum vessel wall, plasma facing components, etc., thus increasing the need to deploy all components within the so-called ``center stack'' in the most efficient manner possible. Several unique design features have been developed for the NSTX center stack, and careful engineering of this region of the machine, utilizing materials up to their engineering allowables, has been key to meeting the desired objectives. The design and construction of the machine has been accomplished in a rapid and cost effective manner thanks to the availability of extensive facilities, a strong experience base from the TFTR era, and good cooperation between institutions.

  3. 2-D Airbreathing Lightcraft Engine Experiments in Quiescent Conditions

    NASA Astrophysics Data System (ADS)

    Salvador, Israel I.; Myrabo, Leik N.; Minucci, Marco A. S.; de Oliveira, Antonio C.; Toro, Paulo G. P.; Chanes, José B.; Rego, Israel S.

    2011-11-01

    Ground-breaking laser propulsion (LP) experiments were performed under quiescent conditions with a 25 cm wide, two-dimensional Lightcraft model using a Lumonics TEA-622 CO2 laser emitting ˜ 1 μs pulses. In preparation for subsequent hypersonic experiments, this static test campaign was conducted at ambient pressures of 0.06, 0.15, 0.30 and 1 bar with laser pulse energies of 150 to 230 J. Time-variant pressure distributions, generated over engine "absorption chamber" walls, were integrated to obtain total impulse and momentum coupling coefficients (Cm) representative of a single propulsion cycle. Schlieren visualization of laser-induced air breakdown and expanding blast waves was also accomplished. Surprisingly, the Cm results of 600-3000 Ns/MJ were 2.5x to 5x greater than previous results from smaller Lightcraft models; this suggests that higher static Cm performance can likely be achieved in larger scale LP engines. This research collaboration, forged between the USAF and Brazilian Air Force, was carried out at the Henry T. Nagamatsu Laboratory of Aerothermodynamics and Hypersonics in Brazil.

  4. Immunosuppressive and anti-inflammatory properties of engineered nanomaterials

    PubMed Central

    Ilinskaya, A N; Dobrovolskaia, M A

    2014-01-01

    Nanoparticle interactions with various components of the immune system are determined by their physicochemical properties such as size, charge, hydrophobicity and shape. Nanoparticles can be engineered to either specifically target the immune system or to avoid immune recognition. Nevertheless, identifying their unintended impacts on the immune system and understanding the mechanisms of such accidental effects are essential for establishing a nanoparticle's safety profile. While immunostimulatory properties have been reviewed before, little attention in the literature has been given to immunosuppressive and anti-inflammatory properties. The purpose of this review is to fill this gap. We will discuss intended immunosuppression achieved by either nanoparticle engineering, or the use of nanoparticles to carry immunosuppressive or anti-inflammatory drugs. We will also review unintended immunosuppressive properties of nanoparticles per se and consider how such properties could be either beneficial or adverse. Linked Articles This article is part of a themed section on Nanomedicine. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-17 PMID:24724793

  5. Engineering Overview of the National Spherical Torus Experiment (NSTX)

    SciTech Connect

    Neumeyer, C. Author

    1997-01-01

    The National Spherical Torus Experiment (NSTX) Project will provide a national facility for the study of plasma confinement, heating, and current drive in a low-aspect-ratio, spherical torus (ST) configuration. The ST configuration is an alternate confinement concept which is characterized by high beta, high elongation, high bootstrap fraction, and low toroidal magnetic field compared to conventional tokamaks. The NSTX is the next-step ST experiment following smaller experiments such as the Princeton Plasma Physics Laboratory CDX-U (Current Drive Experiment-Upgrade), the START (Small Tight Aspect Ratio Tokamak) at Culham Laboratory, UK, and the HIT (Helicity Injected Tokamak) at the University of Washington, and it is smaller in scale to the MAST (Meg-Amp Spherical Tokamak) machine now under construction at Culham.This paper provides a description of the NSTX mission and gives an overview of the main engineering features of the design of the machine and facility and discusses some of the key design solutions.

  6. Reservoir transport and poroelastic properties from oscillating pore pressure experiments

    NASA Astrophysics Data System (ADS)

    Hasanov, Azar K.

    Hydraulic transport properties of reservoir rocks, permeability and storage capacity are traditionally defined as rock properties, responsible for the passage of fluids through the porous rock sample, as well as their storage. The evaluation of both is an important part of any reservoir characterization workflow. Moreover, permeability and storage capacity are main inputs into any reservoir simulation study, routinely performed by reservoir engineers on almost any major oil and gas field in the world. An accurate reservoir simulation is essential for production forecast and economic analysis, hence the transport properties directly control the profitability of the petroleum reservoir and their estimation is vital for oil and gas industry. This thesis is devoted to an integrated study of reservoir rocks' hydraulic, streaming potential and poroelastic properties as measured with the oscillating pore pressure experiment. The oscillating pore pressure method is traditionally used to measure hydraulic transport properties. We modified the method and built an experimental setup, capable of measuring all aforementioned rock properties simultaneously. The measurements were carried out for four conventional reservoir-rock quality samples at a range of oscillation frequencies and effective stresses. An apparent frequency dependence of permeability and streaming potential coupling coefficient was observed. Measured frequency dispersion of drained poroelastic properties indicates an intrinsically inelastic nature of the porous mineral rock frame. Standard Linear Model demonstrated the best fit to the experimental dispersion data. Pore collapse and grain crushing effects took place during hydrostatic loading of the dolomitic sample and were observed in permeability, coupling coefficient and poroelastic measurements simultaneously. I established that hydraulically-measured storage capacities are overestimated by almost one order of magnitude when compared to elastically

  7. Globalization and Organizational Change: Engineers' Experiences and Their Implications for Engineering Education

    ERIC Educational Resources Information Center

    Lucena, Juan C.

    2006-01-01

    The demand for flexible engineers presents significant challenges to engineering education. Among these is the need for engineers to be prepared to understand and deal with organizational change. Yet engineering education and research on engineers have overlooked the impact of organizational change on engineering work. After outlining the impact…

  8. Selected engineering properties and applications of EPS geofoam

    NASA Astrophysics Data System (ADS)

    Elragi, Ahmed Fouad

    Expanded polystyrene (EPS) geofoam is a lightweight material that has been used in engineering applications since at least the 1950s. Its density is about a hundredth of that of soil. It has good thermal insulation properties with stiffness and compression strength comparable to medium clay. It is utilized in reducing settlement below embankments, sound and vibration damping, reducing lateral pressure on substructures, reducing stresses on rigid buried conduits and related applications. This study starts with an overview on EPS geofoam. EPS manufacturing processes are described followed by a review of engineering properties found in previous research work done so far. Standards and design manuals applicable to EPS are presented. Selected EPS geofoam-engineering applications are discussed with examples. State-of-the-art of experimental work is done on different sizes of EPS specimens under different loading rates for better understanding of the behavior of the material. The effects of creep, sample size, strain rate and cyclic loading on the stress strain response are studied. Equations for the initial modulus and the strength of the material under compression for different strain rates are presented. The initial modulus and Poisson's ratio are discussed in detail. Sample size effect on creep behavior is examined. Three EPS projects are shown in this study. The creep behavior of the largest EPS geofoam embankment fill is shown. Results from laboratory tests, mathematical modeling and field records are compared to each other. Field records of a geofoam-stabilized slope are compared to finite difference analysis results. Lateral stress reduction on an EPS backfill retaining structure is analyzed. The study ends with a discussion on two promising properties of EPS geofoam. These are the damping ability and the compressibility of this material. Finite element analysis, finite difference analysis and lab results are included in this discussion. The discussion with the

  9. Synthesis of Hollow Gold-Silver Alloyed Nanoparticles: A "Galvanic Replacement" Experiment for Chemistry and Engineering Students

    ERIC Educational Resources Information Center

    Jenkins, Samir V.; Gohman, Taylor D.; Miller, Emily K.; Chen, Jingyi

    2015-01-01

    The rapid academic and industrial development of nanotechnology has led to its implementation in laboratory teaching for undergraduate-level chemistry and engineering students. This laboratory experiment introduces the galvanic replacement reaction for synthesis of hollow metal nanoparticles and investigates the optical properties of these…

  10. From Geometry to Diagnosis: Experiences of Geomatics in Structural Engineering

    NASA Astrophysics Data System (ADS)

    Riveiro, B.; Arias, P.; Armesto, J.; Caamaño, J. C.; Solla, M.

    2012-07-01

    Terrestrial photogrammetry and laser scanning are technologies that have been successfully used for metric surveying and 3D modelling in many different fields (archaeological and architectural documentation, industrial retrofitting, mining, structural monitoring, road surveying, etc.). In the case of structural applications, these techniques have been successfully applied to 3D modelling and sometimes monitoring; but they have not been sufficiently implemented to date, as routine tools in infrastructure management systems, in terms of automation of data processing and integration in the condition assessment procedures. In this context, this paper presents a series of experiences in the usage of terrestrial photogrammetry and laser scanning in the context of dimensional and structural evaluation of structures. These experiences are particularly focused on historical masonry structures, but modern prestressed concrete bridges are also investigated. The development of methodological procedures for data collection, and data integration in some cases, is tackled for each particular structure (with access limitations, geometrical configuration, range of measurement, etc.). The accurate geometrical information provided by both terrestrial techniques motivates the implementation of such results in the complex, and sometimes slightly approximated, geometric scene that is frequently used in structural analysis. In this sense, quantitative evaluating of the influence of real and accurate geometry in structural analysis results must be carried out. As main result in this paper, a series of experiences based on the usage of photogrammetric and laser scanning to structural engineering are presented.

  11. Experience Paper: Software Engineering and Community Codes Track in ATPESC

    SciTech Connect

    Dubey, Anshu; Riley, Katherine M.

    2016-01-01

    Argonne Training Program in Extreme Scale Computing (ATPESC) was started by the Argonne National Laboratory with the objective of expanding the ranks of better prepared users of high performance computing (HPC) machines. One of the unique aspects of the program was inclusion of software engineering and community codes track. The inclusion was motivated by the observation that the projects with a good scientific and software process were better able to meet their scientific goals. In this paper we present our experience of running the software track from the beginning of the program until now. We discuss the motivations, the reception, and the evolution of the track over the years. We welcome discussion and input from the community to enhance the track in ATPESC, and also to facilitate inclusion of similar tracks in other HPC oriented training programs.

  12. A Pilot Experiment in Collaborative Science and Engineering

    NASA Astrophysics Data System (ADS)

    Steidl, J. H.; GVDA Working Group

    2004-12-01

    We report on a pilot field experiment, meant to demonstrate the value of combining resources from multiple earthquake science and engineering facilities. Our initial intent was to employ a mobile shaker truck from the Network for Earthquake Engineering Simulation (NEES) facility with US Geological Survey (USGS) and Incorporated Research Institutions for Seismology (IRIS) seismographic instrumentation in a single study. The final experiment grew into four studies with additional participation from the Los Alamos National Lab and other NSF-sponsored consortia; the MAEC, SCEC, CENS, and HPWREN. The field experiment piggybacked on an earlier planned inaugural demonstration of NEES facilities, held at the NEES Garner Valley Digital Array (GVDA) site in southern California. We recorded ground motions generated by the `TRex' shaker truck at the GVDA and surrounding Garner Valley during August 18-22, 2004 and will continue to collect earthquake data for several months. Our first study tests the potential for generating and measuring nonlinear sediment response by recording TRex strong shaking on a temporary surface accelerometer micro-array and permanent GVDA down-hole accelerometers. Our second study focuses on ground motion site and basin effects by recording TRex signals at 20 temporary real-time, telemetered seismic stations deployed from the center to the edge of the basin. Earthquake signals recorded on this basin array will allow us to validate the process of extrapolating results from the artificial, surface source to those from natural earthquakes. The relatively small scale of the Garner Valley basin (4 km by 10 km, sediment depths less than 25 m) makes its characterization feasible, but scalable to larger basins elsewhere and motivates our third study in which we conduct a variety of imaging experiments. Basin array data will constrain broad-scale shear and compressional wave tomographic images of the basin structure. To constrain a higher-resolution image along

  13. Engineering the Dynamic Properties of Protein Networks through Sequence Variation

    PubMed Central

    2016-01-01

    The dynamic behavior of macromolecular networks dominates the mechanical properties of soft materials and influences biological processes at multiple length scales. In hydrogels prepared from self-assembling artificial proteins, stress relaxation and energy dissipation arise from the transient character of physical network junctions. Here we show that subtle changes in sequence can be used to program the relaxation behavior of end-linked networks of engineered coiled-coil proteins. Single-site substitutions in the coiled-coil domains caused shifts in relaxation time over 5 orders of magnitude as demonstrated by dynamic oscillatory shear rheometry and stress relaxation measurements. Networks with multiple relaxation time scales were also engineered. This work demonstrates how time-dependent mechanical responses of macromolecular materials can be encoded in genetic information. PMID:27924309

  14. A phenomenographic study of students' experiences with transition from pre-college engineering programs to first-year engineering

    NASA Astrophysics Data System (ADS)

    Salzman, Noah

    Recent national dialogues on the importance of preparing more students for careers in Science, Technology, Engineering, and Mathematics has driven the development of formal and informal learning opportunities for children and adolescents to explore engineering. Despite the growth of these programs, relatively little research exists on how participation in these programs affects students who choose to pursue further study in engineering. The present study addressed this gap through an exploration of the different ways that First-Year Engineering students experience the transition from pre-college engineering to undergraduate engineering studies. Given the focus of this research on students' experiences, phenomenography was chosen to explore the phenomenon of transition from pre-college to first-year engineering at a large, public Midwestern university. This facilitated understanding the range of variation in the ways that students experienced this transition. Twenty-two students with different amounts of participation in a variety of different engineering programs were selected to be interviewed using a purposeful maximum variation sampling strategy. The interviews were guided by a semi-structured interview protocol that encouraged the participants to reflect on their pre-college engineering experiences, their experiences in First-Year Engineering, and the transition between the two domains. The interviews were analyzed using phenomenographic methods to develop an outcome space consisting of five qualitatively different but related ways of experiencing the transition from pre-college to First-Year Engineering. These categories of description included Foreclosure, Frustration, Tedium, Connection, and Engaging Others. With the exception of the first category which was characterized by a lack of passion and commitment to engineering, the remaining four categories formed a hierarchical relationship representing increasing integration in First-Year Engineering. The

  15. Some engineering properties of heavy concrete added silica fume

    SciTech Connect

    Akkaş, Ayşe; Başyiğit, Celalettin; Esen, Serap

    2013-12-16

    Many different types of building materials have been used in building construction for years. Heavy concretes can be used as a building material for critical building as it can contain a mixture of many heavy elements. The barite itself for radiation shielding can be used and also in concrete to produce the workable concrete with a maximum density and adequate structural strength. In this study, some engineering properties like compressive strength, elasticity modules and flexure strength of heavy concretes’ added Silica fume have been investigated.

  16. Some engineering properties of heavy concrete added silica fume

    NASA Astrophysics Data System (ADS)

    Akkaş, Ayşe; Başyiǧit, Celalettin; Esen, Serap

    2013-12-01

    Many different types of building materials have been used in building construction for years. Heavy concretes can be used as a building material for critical building as it can contain a mixture of many heavy elements. The barite itself for radiation shielding can be used and also in concrete to produce the workable concrete with a maximum density and adequate structural strength. In this study, some engineering properties like compressive strength, elasticity modules and flexure strength of heavy concretes' added Silica fume have been investigated.

  17. Pharmaceutical and Toxicological Properties of Engineered Nanomaterials for Drug Delivery

    PubMed Central

    Palombo, Matthew; Deshmukh, Manjeet; Myers, Daniel; Gao, Jieming; Szekely, Zoltan; Sinko, Patrick J.

    2014-01-01

    Novel engineered nanomaterials (ENMs) are being developed to enhance therapy. The physicochemical properties of ENMs can be manipulated to control/direct biodistribution and target delivery, but these alterations also have implications for toxicity. It is well known that size plays a significant role in determining ENM effects since simply nanosizing a safe bulk material can render it toxic. However, charge, shape, rigidity, and surface modifications also have a significant influence on the biodistribution and toxicity of nanoscale drug delivery systems (NDDSs). In this review, NDDSs are considered in terms of platform technologies, materials, and physical properties that impart their pharmaceutical and toxicological effects. Moving forward, the development of safe and effective nanomedicines requires standardized protocols for determining the physical characteristics of ENMs as well as assessing their potential long-term toxicity. When such protocols are established, the remarkable promise of nanomedicine to improve the diagnosis and treatment of human disease can be fulfilled. PMID:24160695

  18. Quantitative ultrasonic evaluation of mechanical properties of engineering materials

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1978-01-01

    Current progress in the application of ultrasonic techniques to nondestructive measurement of mechanical strength properties of engineering materials is reviewed. Even where conventional NDE techniques have shown that a part is free of overt defects, advanced NDE techniques should be available to confirm the material properties assumed in the part's design. There are many instances where metallic, composite, or ceramic parts may be free of critical defects while still being susceptible to failure under design loads due to inadequate or degraded mechanical strength. This must be considered in any failure prevention scheme that relies on fracture analysis. This review will discuss the availability of ultrasonic methods that can be applied to actual parts to assess their potential susceptibility to failure under design conditions.

  19. Mechanical properties of orthodontic wires made of super engineering plastic.

    PubMed

    Maekawa, Minami; Kanno, Zuisei; Wada, Takahiro; Hongo, Toshio; Doi, Hisashi; Hanawa, Takao; Ono, Takashi; Uo, Motohiro

    2015-01-01

    Most orthodontic equipment is fabricated from alloys such as stainless steel, Co-Cr and Ni-Ti because of their excellent elastic properties. In recent years, increasing esthetic demands, metal allergy and interference of metals with magnetic resonance imaging have driven the development of non-metallic orthodontic materials. In this study, we assessed the feasibility of using three super engineering plastics (PEEK, PES and PVDF) as orthodontic wires. PES and PVDF demonstrated excellent esthetics, although PEEK showed the highest bending strength and creep resistance. PEEK and PVDF showed quite low water absorption. Because of recent developments in coloration of PEEK, we conclude that PEEK has many advantageous properties that make it a suitable candidate for use as an esthetic metal-free orthodontic wire.

  20. Nanoindentation in crystal engineering: quantifying mechanical properties of molecular crystals.

    PubMed

    Varughese, Sunil; Kiran, M S R N; Ramamurty, Upadrasta; Desiraju, Gautam R

    2013-03-04

    Nanoindentation is a technique for measuring the elastic modulus and hardness of small amounts of materials. This method, which has been used extensively for characterizing metallic and inorganic solids, is now being applied to organic and metal-organic crystals, and has also become relevant to the subject of crystal engineering, which is concerned with the design of molecular solids with desired properties and functions. Through nanoindentation it is possible to correlate molecular-level properties such as crystal packing, interaction characteristics, and the inherent anisotropy with micro/macroscopic events such as desolvation, domain coexistence, layer migration, polymorphism, and solid-state reactivity. Recent developments and exciting opportunities in this area are highlighted in this Minireview.

  1. Design properties of hydrogel tissue-engineering scaffolds

    PubMed Central

    Zhu, Junmin; Marchant, Roger E

    2011-01-01

    This article summarizes the recent progress in the design and synthesis of hydrogels as tissue-engineering scaffolds. Hydrogels are attractive scaffolding materials owing to their highly swollen network structure, ability to encapsulate cells and bioactive molecules, and efficient mass transfer. Various polymers, including natural, synthetic and natural/synthetic hybrid polymers, have been used to make hydrogels via chemical or physical crosslinking. Recently, bioactive synthetic hydrogels have emerged as promising scaffolds because they can provide molecularly tailored biofunctions and adjustable mechanical properties, as well as an extracellular matrix-like microenvironment for cell growth and tissue formation. This article addresses various strategies that have been explored to design synthetic hydrogels with extracellular matrix-mimetic bioactive properties, such as cell adhesion, proteolytic degradation and growth factor-binding. PMID:22026626

  2. Mountain Plains Learning Experience Guide: Automotive Repair. Course: Engine Repair.

    ERIC Educational Resources Information Center

    Schramm, C.; Osland, Walt

    One of twelve individualized courses included in an automotive repair curriculum, this course covers theory and construction, inspection diagnoses, and service and overhaul of automotive engines. The course is comprised of five units: (1) Fundamentals of Four-Cycle Engines, (2) Engine Construction, (3) Valve Train, (4) Lubricating Systems, and (5)…

  3. The Keller Plan: A Successful Experiment in Engineering Education.

    ERIC Educational Resources Information Center

    Koen, Billy; And Others

    1985-01-01

    Discusses the Keller Plan or personalized system of instruction (PSI), a mastery-oriented, self-paced, modular teaching strategy using student/peer proctors. Success for PSI in chemical engineering, operations research, electrical engineering, and nuclear engineering courses is explained. (DH)

  4. Online Data Resources in Chemical Engineering Education: Impact of the Uncertainty Concept for Thermophysical Properties

    ERIC Educational Resources Information Center

    Kim, Sun Hyung; Kang, Jeong Won; Kroenlein, Kenneth; Magee, Joseph W.; Diky, Vladimir; Muzny, Chris D.; Kazakov, Andrei F.; Chirico, Robert D.; Frenkel, Michael

    2013-01-01

    We review the concept of uncertainty for thermophysical properties and its critical impact for engineering applications in the core courses of chemical engineering education. To facilitate the translation of developments to engineering education, we employ NIST Web Thermo Tables to furnish properties data with their associated expanded…

  5. Engineering of vault nanocapsules with enzymatic and fluorescent properties.

    PubMed

    Kickhoefer, Valerie A; Garcia, Yvette; Mikyas, Yeshi; Johansson, Erik; Zhou, Jing C; Raval-Fernandes, Sujna; Minoofar, Payam; Zink, Jeffrey I; Dunn, Bruce; Stewart, Phoebe L; Rome, Leonard H

    2005-03-22

    One of the central issues facing the emerging field of nanotechnology is cellular compatibility. Nanoparticles have been proposed for diagnostic and therapeutic applications, including drug delivery, gene therapy, biological sensors, and controlled catalysis. Viruses, liposomes, peptides, and synthetic and natural polymers have been engineered for these applications, yet significant limitations continue to prevent their use. Avoidance of the body's natural immune system, lack of targeting specificity, and the inability to control packaging and release are remaining obstacles. We have explored the use of a naturally occurring cellular nanoparticle known as the vault, which is named for its morphology with multiple arches reminiscent of cathedral ceilings. Vaults are 13-MDa ribonucleoprotein particles with an internal cavity large enough to sequester hundreds of proteins. Here, we report a strategy to target and sequester biologically active materials within the vault cavity. Attachment of a vault-targeting peptide to two proteins, luciferase and a variant of GFP, resulted in their sequestration within the vault cavity. The targeted proteins confer enzymatic and fluorescent properties on the recombinant vaults, both of which can be detected by their emission of light. The modified vaults are compatible with living cells. The ability to engineer vault particles with designed properties and functionalities represents an important step toward development of a biocompatible nanocapsule.

  6. EDF's Engineering Experience and Contribution to the Nuclear Development

    SciTech Connect

    Salha, Bernard; Fourest, Bernard; Arpino, Jean-Marc

    2002-07-01

    Electricite de France (EDF) is now operating 58 nuclear power units which produce 76% of the electricity generated in France. This EDF's industrial success is the result of its capacity to master and optimize its production tool, from design through operation. EDF's integrated engineering is in the heart of this process of technical expertise and economic optimization. It allows to be in interface between the needs of operators and industrials suppliers, while accumulating a significant feedback of operating experience. The will of achieving the process of frenchifying PWR technology and to implement new industrial innovations have ended up in the new NPP of 100 % french design, the N4 series and its significant innovations. EDF energy policy is to keep the nuclear option open for the future. This strategy results from the need to improve the availability and the life extension of the units in operation and to prepare the replacement of the operating reactors around 2015. This is the objective of the European Pressurized Reactor (EPR), a French-German joint project. EDF is also applying this industrial process in its international projects. For example China, which desires to implement a standardized nuclear program and to move forward the complete autonomy of its nuclear industry, has decided to adopt a similar approach to EDF's one. (authors)

  7. Elastic-Plastic Properties: Simulation and Experiment

    NASA Astrophysics Data System (ADS)

    Fiedler, Thomas; Öchsner, Andreas

    This chapter addresses the elasto-plastic properties of novel metallic hollow sphere structures (MHSS). Numerical finite element analyses and experimental tests are conducted. The influence of the morphology, topology, joining technology and material composition on their mechanical properties is numerically investigated. Uni-axial compressive tests with adhesively bonded MHSS are performed in order to confirm the numerical findings. Young’s modulus, Poisson’s ratio and the initial plastic yield stress are determined. Furthermore, the elastic anisotropy of simple cubic MHSS is investigated.

  8. Contribution of engineered nanomaterials physicochemical properties to mast cell degranulation

    NASA Astrophysics Data System (ADS)

    Johnson, Monica M.; Mendoza, Ryan; Raghavendra, Achyut J.; Podila, Ramakrishna; Brown, Jared M.

    2017-03-01

    The rapid development of engineered nanomaterials (ENMs) has grown dramatically in the last decade, with increased use in consumer products, industrial materials, and nanomedicines. However, due to increased manufacturing, there is concern that human and environmental exposures may lead to adverse immune outcomes. Mast cells, central to the innate immune response, are one of the earliest sensors of environmental insult and have been shown to play a role in ENM-mediated immune responses. Our laboratory previously determined that mast cells are activated via a non-FcεRI mediated response following silver nanoparticle (Ag NP) exposure, which was dependent upon key physicochemical properties. Using bone marrow-derived mast cells (BMMCs), we tested the hypothesis that ENM physicochemical properties influence mast cell degranulation. Exposure to 13 physicochemically distinct ENMs caused a range of mast degranulation responses, with smaller sized Ag NPs (5 nm and 20 nm) causing the most dramatic response. Mast cell responses were dependent on ENMs physicochemical properties such as size, apparent surface area, and zeta potential. Surprisingly, minimal ENM cellular association by mast cells was not correlated with mast cell degranulation. This study suggests that a subset of ENMs may elicit an allergic response and contribute to the exacerbation of allergic diseases.

  9. Contribution of engineered nanomaterials physicochemical properties to mast cell degranulation

    PubMed Central

    Johnson, Monica M.; Mendoza, Ryan; Raghavendra, Achyut J.; Podila, Ramakrishna; Brown, Jared M.

    2017-01-01

    The rapid development of engineered nanomaterials (ENMs) has grown dramatically in the last decade, with increased use in consumer products, industrial materials, and nanomedicines. However, due to increased manufacturing, there is concern that human and environmental exposures may lead to adverse immune outcomes. Mast cells, central to the innate immune response, are one of the earliest sensors of environmental insult and have been shown to play a role in ENM-mediated immune responses. Our laboratory previously determined that mast cells are activated via a non-FcεRI mediated response following silver nanoparticle (Ag NP) exposure, which was dependent upon key physicochemical properties. Using bone marrow-derived mast cells (BMMCs), we tested the hypothesis that ENM physicochemical properties influence mast cell degranulation. Exposure to 13 physicochemically distinct ENMs caused a range of mast degranulation responses, with smaller sized Ag NPs (5 nm and 20 nm) causing the most dramatic response. Mast cell responses were dependent on ENMs physicochemical properties such as size, apparent surface area, and zeta potential. Surprisingly, minimal ENM cellular association by mast cells was not correlated with mast cell degranulation. This study suggests that a subset of ENMs may elicit an allergic response and contribute to the exacerbation of allergic diseases. PMID:28262689

  10. Enhancing the Programming Experience for First-Year Engineering Students through Hands-On Integrated Computer Experiences

    ERIC Educational Resources Information Center

    Canfield, Stephen L.; Ghafoor, Sheikh; Abdelrahman, Mohamed

    2012-01-01

    This paper describes the redesign and implementation of the course, "Introduction to Programming for Engineers" using microcontroller (MCU) hardware as the programming target. The objective of this effort is to improve the programming competency for engineering students by more closely relating the initial programming experience to the student's…

  11. Electrostatic propulsion beam divergence effects on spacecraft surfaces, volume 3. [effects of ion engine experiment on subsystems of ATS 6 satellite

    NASA Technical Reports Server (NTRS)

    Kemp, R. F.; Hall, D. F.; Luedke, E. E.

    1973-01-01

    Tests were conducted to determine the effects of electrostatic propulsion beam divergence effects on spacecraft surfaces. The subjects discussed are: (1) sensitive surfaces on the ATS 6 spacecraft, (2) the cesium ion source and testing facility, (3) cesium ion effects on thermophysical properties, and (4) simulated charge-exchange ion exposure. The compatibility of the ATS 6 ion engine experiment with the engineering subsystems and other experiments aboard the ATS 6 spacecraft was analyzed.

  12. Turkish Students' Career Choices in Engineering: Experiences from Turkey

    ERIC Educational Resources Information Center

    Cavas, Bulent; Cakiroglu, Jale; Cavas, Pinar; Ertepinar, Hamide

    2011-01-01

    The shortfall of young people, particularly women, in the field of Science, Mathematics and Engineering (SME) has been shown in many national studies. Schreiner and Sjoberg (2007) indicated that boys outnumber girls in physics and engineering studies, while the gender balance is shifted towards the girls in studies including medicine, veterinary…

  13. Experiences with Integrating Simulation into a Software Engineering Curriculum

    ERIC Educational Resources Information Center

    Bollin, Andreas; Hochmuller, Elke; Mittermeir, Roland; Samuelis, Ladislav

    2012-01-01

    Software Engineering education must account for a broad spectrum of knowledge and skills software engineers will be required to apply throughout their professional life. Covering all the topics in depth within a university setting is infeasible due to curricular constraints as well as due to the inherent differences between educational…

  14. Electrical engineering of the optical properties in silicene

    NASA Astrophysics Data System (ADS)

    Bao, Hairui; Guo, Junji; Liao, Wenhu; Zhao, Heping

    2015-02-01

    Based on the intersubband transition theorem of the semiconductors, we have theoretically investigated the optical properties of a three-terminal silicene-based device under the irradiation of a circularly polarized terahertz electromagnetic field. The system spin-orbit-coupled electronic structure may be engineered to topological insulated (TI) and band insulated (BI) state, respectively, by the staggered sublattice potential from the back-gate voltage. It has been demonstrated that the dielectric functions and optical absorption spectra from the TI spin-up and spin-down subbands behave redshift and blueshift, respectively, with the increase in the sublattice potential, while those from the BI spin-up and spin-down subbands have been proven to be continually blue-shifted with the staggered sublattice potential. The novel features may be useful in the design of the spintronic and optoelectronic devices based on silicene.

  15. Building International Experiences into an Engineering Curriculum--A Design Project-Based Approach

    ERIC Educational Resources Information Center

    Maldonado, Victor; Castillo, Luciano; Carbajal, Gerardo; Hajela, Prabhat

    2014-01-01

    This paper is a descriptive account of how short-term international and multicultural experiences can be integrated into early design experiences in an aerospace engineering curriculum. Such approaches are considered as important not only in fostering a student's interest in the engineering curriculum, but also exposing them to a multicultural…

  16. Final Report of the Women's Experiences in College Engineering (WECE) Project

    ERIC Educational Resources Information Center

    Goodman, Irene F.

    2002-01-01

    The Women's Experiences in College Engineering (WECE) project is the first cross-institutional, longitudinal examination of undergraduate women's experiences and persistence in engineering majors. The study was funded by both the National Science Foundation and the Alfred P. Sloan Foundation and conducted by Goodman Research Group, Inc. (GRG), a…

  17. Final Report of The Women's Experiences in College Engineering (WECE) Project. Executive Summary

    ERIC Educational Resources Information Center

    Goodman, Irene F.

    2002-01-01

    The Women's Experiences in College Engineering (WECE) project is the first cross-institutional, longitudinal examination of undergraduate women's experiences and persistence in engineering majors. The study was funded by both the National Science Foundation and the Alfred P. Sloan Foundation and conducted by Goodman Research Group, Inc. (GRG), a…

  18. Viking magnetic properties experiment - Extended mission results

    NASA Technical Reports Server (NTRS)

    Hargraves, R. B.; Collinson, D. W.; Arvidson, R. E.; Cates, P. M.

    1979-01-01

    The backhoe magnets on Viking Lander (VL) 2 were successfully cleaned, followed by a test involving successive insertions of the cleaned backhoe into the surface. Rapid saturation of the magnets confirmed evidence from primary mission results that the magnetic mineral in the Martian surface is widely distributed, most probably in the form of composite particles of magnetic and nonmagnetic minerals. An image of the VL 2 backhoe taken via the X4 magnifying mirror demonstrates the fine-grained nature of the attracted magnetic material. The presence of maghemite and its occurrence as a pigment in, or a thin coating on, all mineral particles or as discrete, finely divided and widely distributed crystallites, are consistent with data from the inorganic analysis experiments and with laboratory simulations of results of the biology experiments on Mars.

  19. Using nonlinear optimization methods to reverse engineer liner material properties from EFP tests

    SciTech Connect

    Murphy, M.J.; Baker, E.L.

    1995-02-27

    The utility of variable metric nonlinear optimization methods for reverse engineering liner material constitutive modeling parameters is described. We use an effective new code created by coupling the nonlinear optimization code NLQPEB with the DYNA2D finite element hydrocode. The optimization code determines the ``best`` set of liner material properties by running DYNA2D in a loop, varying the liner model constitutive parameters, and minimizing the difference between the EFP profiles of the calculation and experiment. The results of four different EFP warhead tests with the same copper liner material are used to determine material parameters for the Steinberg-Guinan, Johnson-Cook, & Armstrong-Zerilli models. In a companion paper we describe the successful application of this methodology to the forward engineering of liner contours to achieve desired EFP shapes. The methodology of utilizing a coupled optimization/finite element code provides a significant improvement in warhead designs and the warhead design process.

  20. The rheological properties of silated hydroxypropylmethylcellulose tissue engineering matrices.

    PubMed

    Fatimi, Ahmed; Tassin, Jean François; Quillard, Sophie; Axelos, Monique A V; Weiss, Pierre

    2008-02-01

    This paper describes the rheological properties of silated hydroxypropylmethylcellulose (HPMC-Si) used in biomaterials domain as a three-dimensional synthetic matrix for tissue engineering. The HPMC-Si is an HPMC grafted with 3-glycidoxypropyltrimethoxysilane (GPTMS). HPMC and HPMC-Si were studied. It is shown that although silanization reduces the hydrodynamic volume in dilute solution, it does not affect significantly the rheological behavior of the concentrated solutions. The HPMC-Si viscous solution (pH 12.8) cross-links by decreasing the pH using an acid buffer, since HPMC-Si solution transforms into an elastic state. The kinetics of cross-linking and final elastic properties is influenced by several parameters such as polymer concentration, pH and temperature. pH and temperature play an important role in the silanol condensation, mainly responsible for network formation. The study of the gelation process revealed the dependence of the final concentration of HPMC-Si hydrogel on cross-linking kinetics and viscoelastic properties. The percolation theory was applied to determine gel point and to discuss the dependence of storage (G') and loss (G'') moduli on frequency. Results showed that both G' and G'' exhibit a power-law behavior with an exponent (0.68) which extends over the entire frequency range. This method is the only one to characterize the time where a liquid viscous phase shifts to hydrogel with elastic properties. In this case it was about 23 min for a final pH of 7.4.

  1. Hygroscopic Properties of Aircraft Engine Exhaust Aerosol Produced From Traditional and Alternative Fuels

    NASA Astrophysics Data System (ADS)

    Moore, R.; Ziemba, L. D.; Beyersdorf, A. J.; Thornhill, K. L.; Winstead, E. L.; Crumeyrolle, S.; Chen, G.; Anderson, B. E.

    2012-12-01

    Aircraft emissions of greenhouse gases and aerosols constitute an important component of anthropogenic climate forcing, of which aerosol-cloud interactions remain poorly understood. It is currently thought that the ability of these aerosols to alter upper tropospheric cirrus cloud properties may produce radiative forcings many times larger than the impact of linear contrails alone and which may partially offset the impact of greenhouse gas emissions from aviation (Burkhardt and Karcher, Nature, 2011). Consequently, it is important to characterize the ability of these engine-emitted aerosol to act as cloud condensation nuclei (CCN) and ice nuclei (IN) to form clouds. While a number of studies in the literature have examined aerosol-cloud interactions for laboratory-generated soot or from aircraft engines burning traditional fuels, limited attention has been given to how switching to alternative jet fuels impacts the ability of engine-emitted aerosols to form clouds. The key to understanding these changes is the aerosol hygroscopicity. To address this need, the second NASA Alternative Aviation Fuel Experiment (AAFEX-II) was conducted in 2011 to examine the aerosol emissions from the NASA DC-8 under a variety of different engine power and fuel type conditions. Five fuel types were considered including traditional JP-8 fuel, synthetic Fischer-Tropsh (FT) fuel , sulfur-doped FT fuel (FTS) , hydrotreated renewable jet (HRJ) fuel, and a 50:50 blend of JP-8 with HRJ. Emissions were sampled from the DC-8 on the airport jetway at a distance of 145 meters downwind of the engine by a comprehensive suite of aerosol instrumentation that provided information on the aerosol concentration, size distribution, soot mass, and CCN activity. Concurrent measurements of carbon dioxide were used to account for plume dilution so that characteristic emissions indices could be determined. It is found that both engine power and fuel type significantly influence the hygroscopic properties of

  2. ATS-6 engineering performance report. Volume 6: Scientific experiments

    NASA Technical Reports Server (NTRS)

    Wales, R. O. (Editor)

    1981-01-01

    Evaluations include a very high resolution radiometer, a radio beacon experiment, environmental measurement experiments (EME), EME support hardware, EME anomalies and failures, EME results, and US/USSR magnetometer experiments.

  3. Some airline experience in preventing engine rotor failures

    NASA Technical Reports Server (NTRS)

    Morelli, J. J.

    1977-01-01

    Methods used by airlines, with the assistance of the engine manufacturers to achieve control over the type of problems which lead to uncontained failure and avoid many potential problems are discussed.

  4. Initial experiments with a laser driven Stirling engine

    NASA Technical Reports Server (NTRS)

    Byer, R. L.

    1976-01-01

    Operation of a Beale free piston Stirling engine with a 40-W CO2 laser is described. Advantages of such a system include: closed-cycle operation, long life, inexpensive construction, and size scalability to 100 MW.

  5. Surface electrical properties experiment, part 1. [flown on Apollo 17

    NASA Technical Reports Server (NTRS)

    Strangway, D. W.; Annan, A. P.; Redman, J. D.; Rossiter, J. R.; Rylaarsdam, J. A.; Watts, R. D.

    1974-01-01

    The work is reported which was performed on the Surface Electrical Properties Experiment Data Acquisition System. Areas discussed include: data handling and processing, installation and external signal application, operation of the equipment, and digital output. Detailed circuit descriptions are included.

  6. Surface electrical properties experiment study phase, volume 2

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The choice of an antenna for a subsurface radio sounding experiment is discussed. The radiation properties of the antennas as placed on the surface of the medium is examined. The objective of the lunar surface electrical properties experiment is described. A numerical analysis of the dielectric permittivity and magnetic permeability of a subsurface domain is developed. The application of electromagnetic field measurements between one or more transmitting antennas and a roving receiving station is explained.

  7. Psychometric properties of the Violent Experiences Questionnaire.

    PubMed

    King, Alan R; Russell, Tiffany D

    2017-02-24

    The Violent Experiences Questionnaire-Revised (VEQ-R) is a brief retrospective self-report inventory which provides estimates of annual frequencies of childhood physical abuse, sibling physical abuse, exposure to parental violence, peer bullying, and corporal punishment as they were experienced from ages 5 to 16. The VEQ-R indices rely on a frequency metric that estimates the number of days on average per year a specified class of behavior occurred over a 12year retrospective period. All scores range from a frequency of 0 to a high of 104. Scale normative data was generated from both a college (N=1266) and national (N=1290) sample to expand the research applicability of this relatively new inventory. Subscales were added to estimate the frequency of victimization during childhood, the pre-teen years, and adolescence. Four "hostility" component indices were derived from perpetrator source (parent, sibling, peer, or domestic). Thresholds were established to for High, Moderate, Low, and No Risk classifications. Subscales dimensions were found to have both adequate internal and temporal consistency. Evidence of concurrent and discriminant validity was generated using the Parent-Child Conflict Tactics Scale-Short-Form(©), LONGSCAN Physical Abuse Self-Report scale, and Physical Punishment scale of the Assessing Environments III inventory.

  8. ATS-6 engineering performance report. Volume 5: Propagation experiments

    NASA Technical Reports Server (NTRS)

    Wales, R. O. (Editor)

    1981-01-01

    Propagation experiments at 1550 MHz to 1650 MHz are reviewed, including the Integrated L-Band Experiments system and results, and the Mobile L-Band Terminals for Satellite Communication system. Experiments at 4 GHz to 6 GHz are reported, including the Radio Frequency Interferometer Measurements system and results, and Earth station antenna evaluations. Experiments above 10 GHz are discussed, including Comsat and ATS-6 millimeter wave propagation/experiments, and communication ATS-6 version at 20 and 30 GHz.

  9. Diesel Surrogate Fuels for Engine Testing and Chemical-Kinetic Modeling: Compositions and Properties.

    PubMed

    Mueller, Charles J; Cannella, William J; Bays, J Timothy; Bruno, Thomas J; DeFabio, Kathy; Dettman, Heather D; Gieleciak, Rafal M; Huber, Marcia L; Kweon, Chol-Bum; McConnell, Steven S; Pitz, William J; Ratcliff, Matthew A

    2016-02-18

    The primary objectives of this work were to formulate, blend, and characterize a set of four ultralow-sulfur diesel surrogate fuels in quantities sufficient to enable their study in single-cylinder-engine and combustion-vessel experiments. The surrogate fuels feature increasing levels of compositional accuracy (i.e., increasing exactness in matching hydrocarbon structural characteristics) relative to the single target diesel fuel upon which the surrogate fuels are based. This approach was taken to assist in determining the minimum level of surrogate-fuel compositional accuracy that is required to adequately emulate the performance characteristics of the target fuel under different combustion modes. For each of the four surrogate fuels, an approximately 30 L batch was blended, and a number of the physical and chemical properties were measured. This work documents the surrogate-fuel creation process and the results of the property measurements.

  10. Diesel Surrogate Fuels for Engine Testing and Chemical-Kinetic Modeling: Compositions and Properties

    PubMed Central

    Mueller, Charles J.; Cannella, William J.; Bays, J. Timothy; Bruno, Thomas J.; DeFabio, Kathy; Dettman, Heather D.; Gieleciak, Rafal M.; Huber, Marcia L.; Kweon, Chol-Bum; McConnell, Steven S.; Pitz, William J.; Ratcliff, Matthew A.

    2016-01-01

    The primary objectives of this work were to formulate, blend, and characterize a set of four ultralow-sulfur diesel surrogate fuels in quantities sufficient to enable their study in single-cylinder-engine and combustion-vessel experiments. The surrogate fuels feature increasing levels of compositional accuracy (i.e., increasing exactness in matching hydrocarbon structural characteristics) relative to the single target diesel fuel upon which the surrogate fuels are based. This approach was taken to assist in determining the minimum level of surrogate-fuel compositional accuracy that is required to adequately emulate the performance characteristics of the target fuel under different combustion modes. For each of the four surrogate fuels, an approximately 30 L batch was blended, and a number of the physical and chemical properties were measured. This work documents the surrogate-fuel creation process and the results of the property measurements. PMID:27330248

  11. Improving the mechanical properties of collagen-based membranes using silk fibroin for corneal tissue engineering.

    PubMed

    Long, Kai; Liu, Yang; Li, Weichang; Wang, Lin; Liu, Sa; Wang, Yingjun; Wang, Zhichong; Ren, Li

    2015-03-01

    Although collagen with outstanding biocompatibility has promising application in corneal tissue engineering, the mechanical properties of collagen-based scaffolds, especially suture retention strength, must be further improved to satisfy the requirements of clinical applications. This article describes a toughness reinforced collagen-based membrane using silk fibroin. The collagen-silk fibroin membranes based on collagen [silk fibroin (w/w) ratios of 100:5, 100:10, and 100:20] were prepared by using silk fibroin and cross-linking by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. These membranes were analyzed by scanning electron microscopy and their optical property, and NaCl and tryptophan diffusivity had been tested. The water content was found to be dependent on the content of silk fibroin, and CS10 membrane (loading 10 wt % of silk fibroin) performed the optimal mechanical properties. Also the suture experiments have proved CS10 has high suture retention strength, which can be sutured in rabbit eyes integrally. Moreover, the composite membrane proved good biocompatibility for the proliferation of human corneal epithelial cells in vitro. Lamellar keratoplasty shows that CS10 membrane promoted complete epithelialization in 35 ± 5 days, and their transparency is restored quickly in the first month. Corneal rejection reaction, neovascularization, and keratoconus are not observed. The composite films show potential for use in the field of corneal tissue engineering.

  12. Kuwaiti Engineers' Perspectives of the Engineering Senior Design (Capstone) Course as Related to Their Professional Experiences

    ERIC Educational Resources Information Center

    AlSagheer, Abdullah

    2010-01-01

    This study looks into transfer of learning and its application in the actual employment of engineering students after graduation. At Kuwait University, a capstone course is being offered that aims to ensure that students amalgamate all kinds of engineering skills to apply to their work. Within a basic interpretive, qualitative study-design…

  13. Characterizing and engineering microtubule properties for use in hybrid nanodevices

    NASA Astrophysics Data System (ADS)

    Jeune-Smith, Yolaine

    The emergence of nanotechnology in materials science research has had a major impact in biotechnology. Nature provides novel materials and structures that can be redesigned and reassembled for engineering purposes. One system in particular is the intracellular transport system consisting of the kinesin motor protein and microtubule. For synthetic devices, either the bead geometry (kinesin motors walking along a microtubule coated surface) or the gliding geometry (microtubules gliding over a kinesin-coated surface) is used. Molecular shuttles, utilizing the gliding geometry, have the potential for use in hybrid nanodevices such as biosensors. The kinesin-powered molecular shuttle has been extensively studied. Advances have been made in controlling activation of the kinesin motors, guiding movement of kinesin motors and cargo loading onto the molecular shuttles. In this dissertation the interest in molecular shuttle development is extended with a research focus on the microtubule filament. The microtubule is a central element in the molecular shuttle. The sensing capabilities and limitations of molecular shuttles are tied to the microtubules. It would be desired to have nanodevices with molecular shuttles of predictable size, speed and lifetime. Three materials properties of the microtubules are examined. First, the microtubule length distribution is measured and compared to the length distribution of synthetic polymers. Post polymerization processing techniques, shearing and annealing, are utilized to try to reduce the polydispersity index of the microtubule length distribution. Second, the effect of kinesin activity on the lifetime of the microtubules is observed and quantified. Degradation of microtubules is monitored as a function of kinesin activity and time. Lastly, the effect of cargo loading on microtubule gliding speed is measured to gain insight on the mechanism of cargo attachment. These property behaviors will play a role in the final development of

  14. How Does Identity Shape the Experiences of Women of Color Engineering Students?

    NASA Astrophysics Data System (ADS)

    Tate, Erika D.; Linn, Marcia C.

    2005-12-01

    This study seeks to understand the experiences of women of color engineering students who persist and identify some of the dilemmas they face. Evidence emerged that students formulate multiple identities to help them persist in their engineering programs. We assess the role that identity plays in the experiences of STEM (science, technology, engineering, and mathematics) women of color. This paper applies a multiple identities framework and presents students' experiences through the lenses of three emergent identities: academic, social, and intellectual. We discuss possible implications of the findings for academic and social support programs in higher education. We also identify some implications for precollege instruction.

  15. ATS-6 engineering performance report. Volume 4: Television experiments

    NASA Technical Reports Server (NTRS)

    Wales, R. O. (Editor)

    1981-01-01

    Experiments sponsored by the US Department of Health Education and Welfare are discussed, including telecommunications, Alaskan health service, Appalachian education satellite project, and the University of the West Indies. The Satellite Instructional Television Experiment in India is reviewed. Independent television experiments are addressed, including AIDSAT and Project Look Up.

  16. Application Experiences of NASTRAN Thermal Analysis in Engineering

    NASA Technical Reports Server (NTRS)

    Go, J. C. D.

    1975-01-01

    The application of the thermal analysis phase of NASTRAN in engineering is described. Some illustrative samples are presented to demonstrate the applicability and limitation of NASTRAN thermal analysis capability. The results of the evaluation of the relative efficiency, applicability and accuracy among NASTRAN, other finite element programs, and finite difference programs are also presented.

  17. Advertising Post-Experience Courses in Science and Engineering

    ERIC Educational Resources Information Center

    Thomas, Edward

    1978-01-01

    Describes ten different forms of advertising that have been used to recruit scientists and engineers to residential postexperience courses. Reports the results of a survey conducted to assess the relative cost-benefit of each advertising method in attracting adult students to specialized postexperience courses. (EM)

  18. Recent Efforts and Experiments in the Construction of Aviation Engines

    NASA Technical Reports Server (NTRS)

    SCHWAGER

    1920-01-01

    It became evident during World War I that ever-increasing demands were being placed on the mean power of aircraft engines as a result of the increased on board equipment and the demands of aerial combat. The need was for increased climbing efficiency and climbing speed. The response to these demands has been in terms of lightweight construction and the adaptation of the aircraft engine to the requirements of its use. Discussed here are specific efforts to increase flying efficiency, such as reduction of the number of revolutions of the propeller from 1400 to about 900 r.p.m. through the use of a reduction gear, increasing piston velocity, locating two crankshafts in one gear box, and using the two-cycle stroke. Also discussed are improvements in the transformation of fuel energy into engine power, the raising of compression ratios, the use of super-compression with carburetors constructed for high altitudes, the use of turbo-compressors, rotary engines, and the use of variable pitch propellers.

  19. Developing a Course in Chemical Engineering Ethics: One Class' Experiences.

    ERIC Educational Resources Information Center

    Watters, James C.; Zoeller, Dominic A.

    1991-01-01

    Discusses several options for the incorporation of minimal coursework involving engineering ethics into an already tightly packed curriculum. Topics include integration versus the stand-alone approach; timeliness of course addition; outline of course content and instructional format; students' reflections and instructor's musings; and an annotated…

  20. Engineering Properties of Bentonite Stabilized with Lime and Phosphogypsum

    NASA Astrophysics Data System (ADS)

    Kumar, Sujeet; Dutta, Rakesh Kumar; Mohanty, Bijayananda

    2014-12-01

    Engineering properties such as compaction, unconfined compressive strength, consistency limits, percentage swell, free swell index, the California bearing ratio and the consolidation of bentonite stabilized with lime and phosphogypsum are presented in this paper. The content of the lime and phosphogypsum varied from 0 to 10 %. The results reveal that the dry unit weight and optimum moisture content of bentonite + 8 % lime increased with the addition of 8 % phosphogypsum. The percentage of swell increased and the free swell index decreased with the addition of 8 % phosphogypsum to the bentonite + 8 % lime mix. The unconfined compressive strength of the bentonite + 8 % lime increased with the addition of 8 % phosphogypsum as well as an increase in the curing period up to 14 days. The liquid limit and plastic limit of the bentonite + 8 % lime increased, whereas the plasticity index remained constant with the addition of 8 % phosphogypsum. The California bearing ratio, modulus of subgrade reaction, and secant modulus increased for the bentonite stabilized with lime and phosphogypsum. The coefficient of the consolidation of the bentonite increased with the addition of 8 % lime and no change with the addition of 8 % phosphogypsum.

  1. Redox properties of an engineered purple Cu(A) azurin.

    PubMed

    Sun, Dapeng; Wang, Xiaotang; Davidson, Victor L

    2002-08-01

    Purple Cu(A) centers are a class of binuclear, mixed-valence copper complexes found in cytochrome c oxidase and nitrous oxide reductase. An engineered Cu(A) protein was formed by replacing a portion of the amino acid sequence that contains three of the ligands to the native type I copper center of Pseudomonas aeruginosa azurin with the corresponding portion of sequence from the Cu(A) center of cytochrome c oxidase from Paracoccus denitrificans [Proc. Natl. Acad. Sci. USA 93 (1996) 461]. Oxidation-reduction midpoint potential (E(m)) values of the Cu(A) azurin of +399+/-10 and +380+/-2mV, respectively, were determined by cyclic voltammetry and spectrochemical titration. An n value of one was obtained, indicating that the redox reaction is cycling between the mixed valence and the fully reduced states. Whereas the E(m) value of native azurin is pH dependent, the E(m) value of Cu(A) azurin is not, as expected for the Cu(A) center. Similarities and differences in the redox properties are discussed in terms of the known crystal structures of Cu(A) centers in cytochrome c oxidase and Cu(A) azurin.

  2. Gaming, texting, learning? Teaching engineering ethics through students' lived experiences with technology.

    PubMed

    Voss, Georgina

    2013-09-01

    This paper examines how young peoples' lived experiences with personal technologies can be used to teach engineering ethics in a way which facilitates greater engagement with the subject. Engineering ethics can be challenging to teach: as a form of practical ethics, it is framed around future workplace experience in a professional setting which students are assumed to have no prior experience of. Yet the current generations of engineering students, who have been described as 'digital natives', do however have immersive personal experience with digital technologies; and experiential learning theory describes how students learn ethics more successfully when they can draw on personal experience which give context and meaning to abstract theories. This paper reviews current teaching practices in engineering ethics; and examines young people's engagement with technologies including cell phones, social networking sites, digital music and computer games to identify social and ethical elements of these practices which have relevance for the engineering ethics curricula. From this analysis three case studies are developed to illustrate how facets of the use of these technologies can be drawn on to teach topics including group work and communication; risk and safety; and engineering as social experimentation. Means for bridging personal experience and professional ethics when teaching these cases are discussed. The paper contributes to research and curriculum development in engineering ethics education, and to wider education research about methods of teaching 'the net generation'.

  3. Design and Development Tools for the Systems Engineering Experience Accelerator. Volume 1

    DTIC Science & Technology

    2015-04-20

    INCOSE) 2012 International Symposium/European Conference on Systems Engineering (EUSEC), Rome , Italy, July 9-12. • Bodner, D., Wade, J., Squires, A...Editor in War Craft III. The map is named Defense of the Ancients (DotA) and has attracted millions of players using it for gaming worldwide. Since its... Rome , Italy. 7. Wade, J. P., "Design and Development Tools for the Systems Engineering Experience Accelerator," Systems Engineering Research

  4. First-Hand Experience with Engineering Design and Career Interest in Engineering: An Informal STEM Education Case Study

    ERIC Educational Resources Information Center

    Ayar, Mehmet C.

    2015-01-01

    The purpose of this study is to present students' experiences, interest in engineering, and personal narratives while participating in a robotics summer camp in a metropolitan city in Turkey. In this study, I used qualitative data collection methods such as interviews, field notes, and observations. I used the four principles of Engle and Conant…

  5. Two Brief Interventions to Mitigate a "Chilly Climate" Transform Women's Experience, Relationships, and Achievement in Engineering

    ERIC Educational Resources Information Center

    Walton, Gregory M.; Logel, Christine; Peach, Jennifer M.; Spencer, Steven J.; Zanna, Mark P.

    2015-01-01

    In a randomized-controlled trial, we tested 2 brief interventions designed to mitigate the effects of a "chilly climate" women may experience in engineering, especially in male-dominated fields. Participants were students entering a selective university engineering program. The "social-belonging intervention" aimed to protect…

  6. Lived Experiences and Perceptions on Mentoring among Latina Scientists and Engineers

    ERIC Educational Resources Information Center

    San Miguel, Anitza M.

    2010-01-01

    The purpose of this qualitative study was to reveal the lived mentoring experiences of Latinas in science and engineering. The study also sought to understand how Latina scientists and engineers achieved high-level positions within their organizations and the impediments they encountered along their professional journey. The theoretical framework…

  7. The Critical Incident Technique: An Effective Tool for Gathering Experience from Practicing Engineers

    ERIC Educational Resources Information Center

    Hanson, James H.; Brophy, Patrick D.

    2012-01-01

    Not all knowledge and skills that educators want to pass to students exists yet in textbooks. Some still resides only in the experiences of practicing engineers (e.g., how engineers create new products, how designers identify errors in calculations). The critical incident technique, CIT, is an established method for cognitive task analysis. It is…

  8. COED Transactions, Vol. X, No. 4, April 1978. An Experience in Teaching "COBOL?" to Graduate Engineers.

    ERIC Educational Resources Information Center

    Bremmer, Dale; Childs, Bart

    This document discusses the importance of computing knowledge and experience in the techniques of fast data retrieval for today's engineer. It describes a course designed to teach the engineer the COBOL Language structure. One of the projects of the course, a report generator (REGE) written in COBOL which is used to alter, sort and print selected…

  9. How to Teach Engineering and Industrial Design: a U.K. Experience.

    ERIC Educational Resources Information Center

    Sheldon, D. F.

    1988-01-01

    Explored are the possibilities of teaching engineering through a project approach. Discussed are the introduction, clashing cultures of industrial and engineering design, skills required of a designer, teaching approach to the total design activity, CAD/CAM experiences, and conclusions. (Author/YP)

  10. Engine and Wiring BDAR Experience and Continued Airworthiness Processes and Tools

    DTIC Science & Technology

    2010-05-01

    Magnetic Interference (EMI) protected wires and cables. Engine and Wiring BDAR Experience and Continued Airworthiness Processes and Tools 12 - 12 RTO...17 Figure 15: Identification that the Frame Cap is Damaged Outboard of the Lightening Hole Between Stringers 3 and 4. Engine and

  11. Engineering Curriculum in the Preschool Classroom: The Teacher's Experience

    ERIC Educational Resources Information Center

    Bagiati, Aikaterini; Evangelou, Demetra

    2015-01-01

    The study presented here focuses on the development of an early education Science, Technology, Engineering and Mathematics (STEM) curriculum with emphasis on engineering. This article presents the teacher's experience as she undertook the task of familiarising herself with the new content and using the curriculum in a university based…

  12. Successful Latina Scientists and Engineers: Their Lived Mentoring Experiences and Career Development

    ERIC Educational Resources Information Center

    San Miguel, Anitza M.; Kim, Mikyong Minsun

    2015-01-01

    Utilizing a phenomenological perspective and method, this study aimed to reveal the lived career mentoring experiences of Latinas in science and engineering and to understand how selected Latina scientists and engineers achieved high-level positions. Our in-depth interviews revealed that (a) it is important to have multiple mentors for Latinas'…

  13. Modal Test Experiences with a Jet Engine Fan Model

    NASA Astrophysics Data System (ADS)

    HOLLKAMP, J. J.; GORDON, R. W.

    2001-11-01

    High cycle fatigue in jet engine blades is caused by excessive vibration. Understanding the dynamic response of the bladed disk system is important in determining vibration levels. Modal testing is a useful tool in understanding the dynamic behavior of structures. However, modal tests are not conducted on bladed disks because of the difficulties involved. One problem is that the overall dynamic behavior is sensitive to small perturbations. Another problem is that multiple inputs and high-resolution techniques are required to separate modes that are nearly repeated. Two studies of engine blade response were recently completed in which bench modal tests were successfully performed on simplified fan models. The modal test procedures for the first study were successful in extracting the modal parameters. But the tests in the second study were more demanding. Ultimately, an approach was devised that accurately extracted the modal parameters. This paper describes the challenges and the evolution of the test procedures.

  14. Fatigue crack monitoring in aero-engines: simulation and experiments

    NASA Astrophysics Data System (ADS)

    Gelman, Leonid M.; Petrunin, Ivan V.; Thompson, Chris

    2004-03-01

    A new genetic approach to fatigue crack monitoring in aero-engine blades is presented. The approach consists of simultaneously using two diagnostic features: the real and imaginary parts of the Fourier transform of vibroacoustical signals. This approach is more fundamental than traditional approaches based on the power spectral density, phase spectrum and Hartley transform; each of these approaches is a special case of the proposed approach. Numerical examples are given based on the processing of signals generated using a nonlinear model of tested blades. The generated signals are the forced vibroacoustical oscillations of cracked and un-cracked blades. The numerical examples show that crack detection ismore effective when using the new approach than when u sing the power spectral density approach. The presented experimental results using un-cracked and cracked turbuine blades from an aero-engine are matched with numerical results. The proposed approach offers an effectiveness improvement over the traditional approach based on power spectral density.

  15. Developing the Systems Engineering Experience Accelerator (SEEA) Prototype and Roadmap

    DTIC Science & Technology

    2012-10-24

    Figure 1: Notional Diagram of the SEEA Prototype Simulator .......................................... 1 Figure 2: A Day in the Life of a PSE ...and Program Systems Engineer ( PSE ) competency model, known as the SPRDE-SE/ PSE . 2. Developing and maturing systems thinking skills. 3. Developing...mental templates which can be applied to similar future situations Figure 2: A Day in the Life of a PSE UNCLASSIFIED Contract Number: H98230

  16. Design of a Film Cooling Experiment for Rocket Engines

    DTIC Science & Technology

    2010-03-01

    velocity v velocity W power YF mass fraction Greek Letter Symbols ε emissivity φ equivalence ratio Δ change π Pi xv γ...TDLAS Tunable Diode Laser Absorption Spectroscopy UCC Ultra Compact Combustor μm micrometers VI Virtual Instrument Xe Xenon ZnSe...In turbine engines, the blowing ratio is important because it represents air bled 9 off the compressor stage and diverted past the combustor

  17. Apollo experience report: Thermal protection from engine-plume environments

    NASA Technical Reports Server (NTRS)

    Taylor, J. T.

    1972-01-01

    Portions of the combined Apollo spacecraft (the command and service module and the lunar module) are subjected to the impingement of hot exhaust gases from the various propulsion systems of the modules. The configurations of the vehicles and the sources of impinging engine plumes are described. A typical Apollo mission is outlined. Protection and design-verification methods are discussed. Finally, recommendations are made for future spacecraft programs.

  18. Apollo experience report: Data management for postflight engineering evaluation

    NASA Technical Reports Server (NTRS)

    Foster, G. B., Jr.

    1974-01-01

    The Apollo management of data for postflight engineering evaluation is described. The sources of Apollo telemetry data, the control of data processing by a single data team, the data techniques used to assist in evaluation of the large quantity of data, and the operation of the data team before the mission and during the evaluation phase are described. The techniques used to ensure the output of valid data and to determine areas in which data were of questionable quality are also included.

  19. A Modular Artificial Intelligence Inference Engine System (MAIS) for support of on orbit experiments

    NASA Technical Reports Server (NTRS)

    Hancock, Thomas M., III

    1994-01-01

    This paper describes a Modular Artificial Intelligence Inference Engine System (MAIS) support tool that would provide health and status monitoring, cognitive replanning, analysis and support of on-orbit Space Station, Spacelab experiments and systems.

  20. Foundations for value education in engineering: the Indian experience.

    PubMed

    Gupta, Amitabha

    2015-04-01

    The objective of this paper is to discuss some of the foundational issues centering around the question of integrating education in human values with professional engineering education: its necessity and justification. The paper looks at the efforts in 'tuning' the technical education system in India to the national goals in the various phases of curriculum development. The contribution of the engineering profession in national development and India's self-sufficiency is crucially linked with the institutionalization of expertise and the role of morality and responsibility. This linkage can be created through a proper understanding of the social role of the profession-what motivates the professionals and what makes professional life meaningful. Value education facilitates the process of moral maturity and the development of a 'holistic' mindset. This paper deals with the need to create such a mindset, the human values associated with it and gives examples of efforts to impart such education through 'action-oriented' programmes introduced in some institutes of engineering in India.

  1. ECR Discharge Ion Engines and Their Space Experiences

    NASA Astrophysics Data System (ADS)

    Kuninaka, Hitoshi; Nakai, Tatsuya; Nishiyama, Kazutaka

    2006-10-01

    Ion engine μ10 has a long life and high reliability because of electrodeless ECR plasma generation in both the ion generator and the neutralizer using 4GHz microwave. Measurements on the electron energy distribution in the ion generator revealed the discharge mechanism to heat gradually a part of the thermal electron along magnetic track. The high-energy electrons generate ions in collision process and return to the thermal electrons. The recycling process of electrons results in the effective plasma generation in comparison with the DC discharge ion generator, in which the high-energy electrons are expendable. Four μ10, each generating a thrust of 8 mN, specific impulse of 3,200 seconds, and consuming 350 W of electric power, propel the ``HAYABUSA'' asteroid explorer launched on May 2003. After vacuum exposure and several runs of baking to reduce residual gas, the ion engine system established continuous acceleration. In 2005, HAYABUSA, using solar electric propulsion, managed to successfully cover the distance between 0.86 AU and 1.7 AU in the solar system, as well as rendezvous with, land on, and lift off from the asteroid. During the 3-year flight, the ion engine system generated a delta-V of 1,400 m/s while consuming 22 kg of xenon propellant and operating for 25,900 hours.

  2. Sewage sludge to landfill: some pertinent engineering properties.

    PubMed

    O'Kelly, Brendan C

    2005-06-01

    More stringent controls on the quality of wastewater discharges have given rise to increasing volumes of sewage sludge for disposal, principally to land, using either land-spreading or sludge-to-landfill operations. Current sludge-to-landfill methods generally involve mixing the concentrated sludge with other solid waste in municipal landfills. However, stricter waste disposal legislation and higher landfill taxes are forcing the water industry to look for more efficient disposal strategies. Landfill operators are also increasingly reluctant to accept sludge material in the slurry state because of construction difficulties and the potential for instability of the landfill slopes. The engineering and drying properties of a municipal sewage sludge are presented and applied, in particular, to the design, construction, and performance of sewage sludge monofills. Sludge handling and landfill construction are most effectively conducted within the water content range of 85% water content, the optimum water content for standard proctor compaction, and 95% water content, the sticky limit of the sludge material. Standard proctor compaction of the sludge within this water content range also achieves the maximum dry density of approximately 0.56 tonne/m3, which maximizes the storage capacity and, hence, the operational life of the landfill site. Undrained shear strength-water content data (pertinent to the stability of the landfill body during construction) and effective stress-strength parameters, which take into account the landfill age and the effects of ongoing sludge digestion, are presented. Landfill subsidence, which occurs principally because of creep and decomposition of the solid organic particles, is significant and continues indefinitely but at progressively slower rates.

  3. [Cariogenic properties of various snacks in animal experiments].

    PubMed

    Karle, E J; Gehring, F; Trautner, K

    1977-09-01

    In a conventional animal experiment with rats, the cariogenic properties of different snacks were studied and compared. Bananas caused the highest caries incidence, apples the lowest. In between ranged the caries values of two other tested sweets, wafers and gum drops. The differences in caries incidence were due to specific chemo-physical properties (stickiness, fat content). In addition to the evaluation of caries incidence, microbiological plaque examinations and sugar analyses of the tested substances were carried out.

  4. Experiments on heat transfer in a cryogenic engine thrust chamber

    NASA Astrophysics Data System (ADS)

    Sugathan, N.; Srinivasan, K.; Srinivasa Murthy, S.

    1993-04-01

    Tests are conducted on a cryogenic engine using liquid oxygen as oxidizer and gaseous hydrogen as fuel with water as a coolant. The coolant flow passage of the thrust chamber is of milled channel configuration. Measured heat transfer results compare well with those predicted by a thermal analysis using the standard Bartz correlation and the Hess and Kunz correlation for hot gas side and coolant side heat transfer coefficients, respectively. This confirms the conclusions of a recent theoretical study by the authors in which a comparison of various heat transfer correlations was made.

  5. Closing the loop on improvement: Packaging experience in the Software Engineering Laboratory

    NASA Technical Reports Server (NTRS)

    Waligora, Sharon R.; Landis, Linda C.; Doland, Jerry T.

    1994-01-01

    As part of its award-winning software process improvement program, the Software Engineering Laboratory (SEL) has developed an effective method for packaging organizational best practices based on real project experience into useful handbooks and training courses. This paper shares the SEL's experience over the past 12 years creating and updating software process handbooks and training courses. It provides cost models and guidelines for successful experience packaging derived from SEL experience.

  6. Synthesis and Physical Properties of Liquid Crystals: An Interdisciplinary Experiment

    ERIC Educational Resources Information Center

    Van Hecke, Gerald R.; Karukstis, Kerry K.; Hanhan Li; Hendargo, Hansford C.; Cosand, Andrew J.; Fox, Marja M.

    2005-01-01

    A study involves multiple chemistry and physics concepts applied to a state of matter that has biological relevance. An experiment involving the synthesis and physical properties of liquid crystals illustrates the interdisciplinary nature of liquid crystal research and the practical devices derived from such research.

  7. An Experiment on the Inertial Properties of a Rigid Body.

    ERIC Educational Resources Information Center

    Armstrong, H. L.

    1985-01-01

    Presents an experiment which focuses on the inertial properties of a rigid body as expressed in terms of principal axes and moments of inertia. Background information, a description of the apparatus needed, and a discussion of results obtained are included. (JN)

  8. Multiple case study analysis of young women's experiences in high school engineering

    NASA Astrophysics Data System (ADS)

    Pollock, Meagan C.

    At a time when engineers are in critical demand, women continue to be significantly underrepresented in engineering fields (11.7%) and degree programs (21.3%) in the United States. As a result, there is a national demand for improved K-12 STEM education and targeted efforts to improve equity and access to engineering and science careers for every underrepresented group. High school engineering has become a nascent and growing market for developers and an emergent opportunity for students across the United States to learn introductory engineering skills through strategic career pathways; however there is a disparity in participation at this level as well. Much useful research has been used to examine the problematization of underrepresentation (K Beddoes, 2011), but there is a dearth of literature that helps us to understand the experiences of young women in high school engineering. By examining the experiences of young women in high school engineering, we can learn ways to improve the curriculum, pedagogy, and environment for underrepresented groups such as females to ensure they have equitable access to these programs and are subsequently motivated to persist in engineering. Understanding the needs of marginalized groups is complex, and intersectional feminism seeks to understand gender in relation to other identities such as race, class, ethnicity, sexuality, and nationality. This theory asserts that gender alone is neither a total identity nor a universal experience, and it is thus advantageous to consider each of the intersecting layers of identity so as to not privilege a dominate group as representative of all women. Thus, to understand how female students engage with and experience engineering in grade school, it is useful to examine through the lens of gender, class, race, and sexuality, because this intersection frames much of the human experience. The purpose of this study is to examine high school females' experiences in engineering, with a goal to

  9. Metallized Gelled Propellants Combustion Experiments in a Pulse Detonation Engine

    NASA Technical Reports Server (NTRS)

    Palaszewski, Bryan; Jurns, John; Breisacher, Kevin; Kearns, Kim

    2006-01-01

    A series of combustion tests were performed with metallized gelled JP 8/aluminum fuels in a Pulse Detonation Engine (PDE). Nanoparticles of aluminum were used in the 60 to 100 nanometer diameter. Gellants were also of a nanoparticulate type composed of hydrocarbon alkoxide materials. Using simulated air (a nitrogen-oxygen mixture), the ignition potential of metallized gelled fuels with nanoparticle aluminum was investigated. Ignition of the JP 8/aluminum was possible with less than or equal to a 23-wt% oxygen loading in the simulated air. JP 8 fuel alone was unable to ignite with less than 30 percent oxygen loaded simulated air. The tests were single shot tests of the metallized gelled fuel to demonstrate the capability of the fuel to improve fuel detonability. The tests were conducted at ambient temperatures and with maximal detonation pressures of 1340 psia.

  10. Software engineering and data management for automated payload experiment tool

    NASA Technical Reports Server (NTRS)

    Maddux, Gary A.; Provancha, Anna; Chattam, David

    1994-01-01

    The Microgravity Projects Office identified a need to develop a software package that will lead experiment developers through the development planning process, obtain necessary information, establish an electronic data exchange avenue, and allow easier manipulation/reformatting of the collected information. An MS-DOS compatible software package called the Automated Payload Experiment Tool (APET) has been developed and delivered. The objective of this task is to expand on the results of the APET work previously performed by UAH and provide versions of the software in a Macintosh and Windows compatible format.

  11. Software engineering and data management for automated payload experiment tool

    NASA Technical Reports Server (NTRS)

    Maddux, Gary A.; Provancha, Anna; Chattam, David

    1994-01-01

    The Microgravity Projects Office identified a need to develop a software package that will lead experiment developers through the development planning process, obtain necessary information, establish an electronic data exchange avenue, and allow easier manipulation/reformatting of the collected information. An MS-DOS compatible software package called the Automated Payload Experiment Tool (APET) has been developed and delivered. The objective of this task is to expand on the results of the APET work previously performed by University of Alabama in Huntsville (UAH) and provide versions of the software in a Macintosh and Windows compatible format. Appendix 1 science requirements document (SRD) Users Manual is attached.

  12. Precooled turbojet engine flight experiment using balloon-based operation vehicle

    NASA Astrophysics Data System (ADS)

    Fujita, K.; Sawai, S.; Kobayashi, H.; Tsuboi, N.; Taguchi, H.; Kojima, T.; Okai, K.; Sato, T.; Miyaji, Koji

    2006-07-01

    Development of the Balloon-based Operation Vehicle (BOV) is currently in progress for the first flight scheduled in 2006. In a series of BOV experiments, a vehicle in a wing-body configuration is lifted by a high-altitude balloon and dropped, after which the microgravity experiments will be performed onboard the vehicle under favor of the quasi-free-fall environments. Although the BOV is originally designed for the microgravity experiments, various types of experiments can also be performed in a hypersonic flight at lower altitudes. One candidate currently under review is a flight experiment of a precooled turbojet engine in reduced dimension. In this article, an overview of the BOV experiment is introduced, and the current development status of the BOV and a flight model of the precooled turbojet engine is presented. The aerodynamic load and the aerodynamic characteristics of the BOV are obtained by computational fluid-dynamic analyses and wind-tunnel experiments.

  13. Sustaining liminality: Experiences and negotiations of international females in U.S. engineering graduate programs

    NASA Astrophysics Data System (ADS)

    Dutta, Debalina

    This project examines the intersectionalities of international females in engineering graduate programs of the United States, using frameworks of sustainability and liminality theory. According to Dutta and Kisselburgh (2011) international females in graduate engineering constitute the minorities of minorities, not only in terms of their status as international students but also by their underrepresentation as women in engineering (Faulkner, 2009). Research regarding international female graduate students tends to be categorized as the experiences of international students in the U.S. (Lee & Rice, 2007), or as the struggles of female engineers in engineering disciplines (Tonso, 2007). Therefore, this project aims to distinguish the unique population of female engineers of international origin from holistic studies of international students, and attempts to draw out and understand the experiences of international female students in U.S. engineering graduate programs. Dutta and Kisselburgh (2011) found that female engineers who are international in origin exist in liminal states indefinitely. This liminal nature has been described under the theory of liminality (Turner, 1967) which posits that when transitioning from one life-changing event to another (such as birth, death, marriage), individuals go through a transformatory phase where they are subjected to invisibility, vulnerability, and a feeling of loss. Although Turner posited this phase as transcendental and temporary, Dutta and Kisselburgh (2011) suggest the liminal period can be more permanent in contemporary global societies. In other words, liminal experiences of vulnerability and structural invisibility may be sustained experiences of international female engineering students. Furthermore, the project attends to the overlaps, tensions and challenging experiences faced by international females in surviving engineering graduate program. To achieve this goal, liminality theory is limited in accounting for how

  14. Top Quark Properties Measurements with the ATLAS Experiment

    NASA Astrophysics Data System (ADS)

    Murillo Quijada, J. A.

    2016-10-01

    Results on recent measurements of top quark properties with the ATLAS experiment at the European Laboratory, CERN, are shown. The measurements are performed using the full data set recorded during the LHC Run-I. The full data set consists of a collected integrated luminosities ∫Tdt of 4.6 fb-1 recorded at a proton-proton collision energy of √s = 7 TeV and 20.3 fb-1 collected at 8 TeV. The mentioned top quark properties include: spin correlation, charge asymmetry, W-boson polarization, color flow, top mass and top width in events with a top and anti-top quark pair (tt). An introduction to the LHC and the ATLAS detector is included and latest main results from this experiment. The contents include the current world benchmark results for the different properties and plans for future measurements during the ongoing LHC Run-II.

  15. Shock wave experiments to examine the multiphase properties of cerium

    SciTech Connect

    Jensen, Brian James

    2009-01-01

    There is a scientific need to obtain new data to constrain and refine next generation multi-phase equation-of-state (EOS) for metals. Experiments are needed to locate phase boundaries, determine transition kinetic times, and to obtain EOS and Hugoniot data for relevant phases. The objectives of the current work was to examine the multiphase properties for cerium including the dynamic melt boundary and the low-pressure solid-solid phase transition through the critical point. These objectives were addressed by performing plate impact experiment that used multiple experimental configuration including front-surface impact experiments to directly measure transition kinetics, multislug experiments that used the overtake method to measure sound speeds at pressure, and preheat experiments to map out phase boundaries. Preliminary data and analysis obtained for cerium will be presented.

  16. On Design Experiment Teaching in Engineering Quality Cultivation

    ERIC Educational Resources Information Center

    Chen, Xiao

    2008-01-01

    Design experiment refers to that designed and conducted by students independently and is surely an important method to cultivate students' comprehensive quality. According to the development and requirements of experimental teaching, this article carries out a study and analysis on the purpose, significance, denotation, connotation and…

  17. A business process modeling experience in a complex information system re-engineering.

    PubMed

    Bernonville, Stéphanie; Vantourout, Corinne; Fendeler, Geneviève; Beuscart, Régis

    2013-01-01

    This article aims to share a business process modeling experience in a re-engineering project of a medical records department in a 2,965-bed hospital. It presents the modeling strategy, an extract of the results and the feedback experience.

  18. The Characteristics and Experiences of Successful Undergraduate Latina Students Who Persist in Engineering

    NASA Astrophysics Data System (ADS)

    Robinson, Carrie

    Females and underrepresented ethnic minorities earn a small percentage of engineering and computer science bachelor's degrees awarded in the United States, earn an even smaller proportion of master's and doctoral degrees, and are underrepresented in the engineering workforce (Engineering Workforce Commission, [2006], as cited in National Science Foundation, 2012; United States Department of Education, [2006], as cited in National Science Foundation, 2009a; United States Department of Education, [2006], as cited in National Science Foundation, 2009b). Considerable research has examined the perceptions, culture, curriculum, and pedagogy in engineering that inhibits the achievement of women and underrepresented ethnic minorities. This action research study used a qualitative approach to examine the characteristics and experiences of Latina students who pursued a bachelor's degree in the Ira A. Fulton Schools of Engineering at Arizona State University (ASU) as part of the 2008 first-time full-time freshman cohort. The researcher conducted two semi-structured individual interviews with seven undergraduate Latina students who successfully persisted to their fourth (senior) year in engineering. The researcher aimed to understand what characteristics made these students successful and how their experiences affected their persistence in an engineering major. The data collected showed that the Latina participants were motivated to persist in their engineering degree program due to their parents' expectations for success and high academic achievement; their desire to overcome the discrimination, stereotyping, and naysayers that they encountered; and their aspiration to become a role model for their family and other students interested in pursuing engineering. From the data collected, the researcher provided suggestions to implement and adapt educational activities and support systems within the Ira A. Fulton Schools of Engineering to improve the retention and graduation rates

  19. Local Government Planning Tool to Calculate Institutional and Engineering Control Costs for Brownfield Properties

    EPA Pesticide Factsheets

    This cost calculator is designed as a guide for municipal or local governments to assist in calculating their expected costs of implementing and conducting long-term stewardship of institutional controls and engineering controls at brownfield properties.

  20. New Mass Properties Engineers Aerospace Ballasting Challenge Facilitated by the SAWE Community

    NASA Technical Reports Server (NTRS)

    Cutright, Amanda; Shaughnessy, Brendan

    2010-01-01

    The discipline of Mass Properties Engineering tends to find the engineers; not typically vice versa. In this case, two engineers quickly found their new responsibilities deep in many aspects of mass properties engineering and required to meet technical challenges in a fast paced environment. As part of NASA's Constellation Program, a series of flight tests will be conducted to evaluate components of the new spacecraft launch vehicles. One of these tests is the Pad Abort 1 (PA-1) flight test which will test the Launch Abort System (LAS), a system designed to provide escape for astronauts in the event of an emergency. The Flight Test Articles (FTA) used in this flight test are required to match mass properties corresponding to the operational vehicle, which has a continually evolving design. Additionally, since the structure and subsystems for the Orion Crew Module (CM) FTA are simplified versions of the final product, thousands of pounds of ballast are necessary to achieve the desired mass properties. These new mass properties engineers are responsible for many mass properties aspects in support of the flight test, including meeting the ballasting challenge for the CM Boilerplate FTA. SAWE expert and experienced mass properties engineers, both those that are directly on the team and many that supported via a variety of Society venues, significantly contributed to facilitating the success of addressing this particular mass properties ballasting challenge, in addition to many other challenges along the way. This paper discusses the details regarding the technical aspects of this particular mass properties challenge, as well as identifies recommendations for new mass properties engineers that were learned from the SAWE community along the way.

  1. Developing the Systems Engineering Experience Accelerator (SEEA) Prototype and Roadmap

    DTIC Science & Technology

    2013-12-31

    reliance on Flash which is a proprietary standard not being supported in some Apple client devices (e.g., iPad and iPhone). The likely standard to be...more specific information. A new dashboard was designed and revised during the classroom prototyping and is shown in Figure 4. It provides immediate...Initially, the EA was considered to be a stand-alone experience. However, the DAU classroom environment led us to investigate other modes. Of particular

  2. Kuwaiti engineers' perspectives of the engineering senior design (Capstone) course as related to their professional experiences

    NASA Astrophysics Data System (ADS)

    Alsagheer, Abdullah

    This study looks into transfer of learning and its application in the actual employment of engineering students after graduation. At Kuwait University, a capstone course is being offered that aims to ensure that students amalgamate all kinds of engineering skills to apply to their work. Within a basic interpretive, qualitative study-design methodology, I interviewed 12 engineers who have recently experienced the senior design course at Kuwait University and are presently working in industry. From the analysis, four basic themes emerged that further delineate the focus of the entire study. The themes are 1) need for the capstone course, 2) applicability of and problems with the capstone course, 3) industry problems with training, and 4) students' attitudes toward the capstone course. The study concludes that participants are not transferring engineering skills; rather, they are transferring all types of instructions they have been given during their course of study at the university. A frequent statement is that the capstone course should be improved and specifically that it is necessary to improve upon the timing, schedule, teachers' behavior, contents, and format. The study concludes that Kuwaiti engineers on the whole face problems with time management and management support. The study includes some implications for Kuwait University and recommendations that can provide significant support for the development of the Senior Design (Capstone) Course. For examples: the project must be divided into phases to ensure timely completion of deliverables. In order to motivate students for hard work and to achieve true transfer of learning, Kuwait University is required to communicate with certain organizations to place its students at their research centers for capstone projects. All universities, including Kuwait University, should hire faculty specifically to run the capstone course. In conclusion, the study includes some suggestions for further research studies focused

  3. Rocket Engine Turbine Blade Surface Pressure Distributions Experiment and Computations

    NASA Technical Reports Server (NTRS)

    Hudson, Susan T.; Zoladz, Thomas F.; Dorney, Daniel J.; Turner, James (Technical Monitor)

    2002-01-01

    Understanding the unsteady aspects of turbine rotor flow fields is critical to successful future turbine designs. A technology program was conducted at NASA's Marshall Space Flight Center to increase the understanding of unsteady environments for rocket engine turbines. The experimental program involved instrumenting turbine rotor blades with miniature surface mounted high frequency response pressure transducers. The turbine model was then tested to measure the unsteady pressures on the rotor blades. The data obtained from the experimental program is unique in two respects. First, much more unsteady data was obtained (several minutes per set point) than has been possible in the past. Also, an extensive steady performance database existed for the turbine model. This allowed an evaluation of the effect of the on-blade instrumentation on the turbine's performance. A three-dimensional unsteady Navier-Stokes analysis was also used to blindly predict the unsteady flow field in the turbine at the design operating conditions and at +15 degrees relative incidence to the first-stage rotor. The predicted time-averaged and unsteady pressure distributions show good agreement with the experimental data. This unique data set, the lessons learned for acquiring this type of data, and the improvements made to the data analysis and prediction tools are contributing significantly to current Space Launch Initiative turbine airflow test and blade surface pressure prediction efforts.

  4. Engineering and simulation of life science Spacelab experiments

    NASA Technical Reports Server (NTRS)

    Bush, B.; Rummel, J.; Johnston, R. S.

    1977-01-01

    Approaches to the planning and realization of Spacelab life sciences experiments, which may involve as many as 16 Space Shuttle missions and 100 tests, are discussed. In particular, a Spacelab simulation program, designed to evaluate problems associated with the use of live animal specimens, the constraints imposed by zero gravity on equipment operation, training of investigators and data management, is described. The simulated facility approximates the hardware and support systems of a current European Space Agency Spacelab model. Preparations necessary for the experimental program, such as crew activity plans, payload documentation and inflight experimental procedures are developed; health problems of the crew, including human/animal microbial contamination, are also assessed.

  5. Implementing an integrated engineering data base system: A developer's experience and the application to IPAD

    NASA Technical Reports Server (NTRS)

    Bruce, E. A.

    1980-01-01

    The software developed by the IPAD project, a new and very powerful tool for the implementation of integrated Computer Aided Design (CAD) systems in the aerospace engineering community, is discussed. The IPAD software is a tool and, as such, can be well applied or misapplied in any particular environment. The many benefits of an integrated CAD system are well documented, but there are few such systems in existence, especially in the mechanical engineering disciplines, and therefore little available experience to guide the implementor.

  6. SSSFD manipulator engineering using statistical experiment design techniques

    NASA Technical Reports Server (NTRS)

    Barnes, John

    1991-01-01

    The Satellite Servicer System Flight Demonstration (SSSFD) program is a series of Shuttle flights designed to verify major on-orbit satellite servicing capabilities, such as rendezvous and docking of free flyers, Orbital Replacement Unit (ORU) exchange, and fluid transfer. A major part of this system is the manipulator system that will perform the ORU exchange. The manipulator must possess adequate toolplate dexterity to maneuver a variety of EVA-type tools into position to interface with ORU fasteners, connectors, latches, and handles on the satellite, and to move workpieces and ORUs through 6 degree of freedom (dof) space from the Target Vehicle (TV) to the Support Module (SM) and back. Two cost efficient tools were combined to perform a study of robot manipulator design parameters. These tools are graphical computer simulations and Taguchi Design of Experiment methods. Using a graphics platform, an off-the-shelf robot simulation software package, and an experiment designed with Taguchi's approach, the sensitivities of various manipulator kinematic design parameters to performance characteristics are determined with minimal cost.

  7. Engineering and simulation of life sciences Spacelab experiments

    NASA Technical Reports Server (NTRS)

    Johnston, R. S.; Bush, W. H. Jr; Rummel, J. A.; Alexander, W. C.

    1979-01-01

    The third in a series of Spacelab Mission Development tests was conducted at the Johnson (correction of Johnston) Space Center as a part of the development of Life Sciences experiments for the Space Shuttle era. The latest test was a joint effort of the Ames Research and Johnson Space Centers and utilized animals and men for study. The basic objective of this test was to evaluate the operational concepts planned for the Space Shuttle life science payloads program. A three-man crew (Mission Specialist and two Payload Specialists) conducted 26 experiments and 12 operational tests, which were selected for this 7-day mission simulation. The crew lived on board a simulated Orbiter/Spacelab mockup 24 hr a day. The Orbiter section contained the mid deck crew quarters area, complete with sleeping, galley and waste management provisions. The Spacelab was identical in geometry to the European Space Agency Spacelab design, complete with removable rack sections and stowage provisions. Communications between the crewmen and support personnel were configured and controlled as currently planned for operational shuttle flights. For this test a Science Operations Remote Center was manned at the Ames Research Center and was managed by simulated Mission Control and Payload Operation Control Centers at the Johnson Space Center. This paper presents the test objectives, description of the facilities and test program, and the results of this test.

  8. Engineering and simulation of life sciences Spacelab experiments.

    PubMed

    Johnston, R S; Bush, W H; Rummel, J A; Alexander, W C

    1979-10-01

    The third in a series of Spacelab Mission Development tests was conducted at the Johnson (correction of Johnston) Space Center as a part of the development of Life Sciences experiments for the Space Shuttle era. The latest test was a joint effort of the Ames Research and Johnson Space Centers and utilized animals and men for study. The basic objective of this test was to evaluate the operational concepts planned for the Space Shuttle life science payloads program. A three-man crew (Mission Specialist and two Payload Specialists) conducted 26 experiments and 12 operational tests, which were selected for this 7-day mission simulation. The crew lived on board a simulated Orbiter/Spacelab mockup 24 hr a day. The Orbiter section contained the mid deck crew quarters area, complete with sleeping, galley and waste management provisions. The Spacelab was identical in geometry to the European Space Agency Spacelab design, complete with removable rack sections and stowage provisions. Communications between the crewmen and support personnel were configured and controlled as currently planned for operational shuttle flights. For this test a Science Operations Remote Center was manned at the Ames Research Center and was managed by simulated Mission Control and Payload Operation Control Centers at the Johnson Space Center. This paper presents the test objectives, description of the facilities and test program, and the results of this test.

  9. Theta13 Neutrino Experiment at the Diablo Canyon Power Plant, LBNL Engineering Summary Report

    SciTech Connect

    Oshatz, Daryl

    2004-03-12

    This summary document describes the results of conceptual design and cost estimates performed by LBNL Engineering staff between October 10, 2003 and March 12, 2004 for the proposed {theta}{sub 13} neutrino experiment at the Diablo Canyon Power Plant (DCPP). This document focuses on the detector room design concept and mechanical engineering issues associated with the neutrino detector structures. Every effort has been made not to duplicate information contained in the last LBNL Engineering Summary Report dated October 10, 2003. Only new or updated information is included in this document.

  10. Surface electrical properties experiment study phase, volume 1

    NASA Technical Reports Server (NTRS)

    Meyer, J. W.; Baker, R. H.; Johnson, L. B.

    1973-01-01

    The evolution of a conceptual design of the flight hardware for the surface electrical properties experiment (SEP), the definition of requests for proposals, the analysis of proposals submitted by prospective flight hardware subcontractors, and recommendations for the flight configuration to be implemented are discussed. Initial efforts were made to assess the electromagnetic environment of the SEP experiment. An EMI receiver and tri-loop antenna were constructed and tests of opportunity were performed with a lunar roving vehicle (LRV). Initial analyses were made of data from these tests with support from this contract, analyses which were continued in depth under the hardware contract.

  11. Low Energy Sputtering Experiments for Ion Engine Lifetime Assessment

    NASA Technical Reports Server (NTRS)

    Duchemin Olivier B.; Polk, James E.

    1999-01-01

    The sputtering yield of molybdenum under xenon ion bombardment was measured using a Quartz Crystal Microbalance. The measurements were made for ion kinetic energies in the range 100-1keV on molybdenum films deposited by magnetron sputtering in conditions optimized to reproduce or approach bulk-like properties. SEM micrographs for different anode bias voltages during the deposition are compared, and four different methods were implemented to estimate the density of the molybdenum films. A careful discussion of the Quartz Crystal Microbalance is proposed and it is shown that this method can be used to measure mass changes that are distributed unevenly on the crystal electrode surface, if an analytical expression is known for the differential mass-sensitivity of the crystal and the erosion profile. Finally, results are presented that are in good agreement with previously published data, and it is concluded that this method holds the promise of enabling sputtering yield measurements at energies closer to the threshold energy in the very short term.

  12. Transient Hypoxia Improves Matrix Properties in Tissue Engineered Cartilage

    PubMed Central

    Yodmuang, Supansa; Gadjanski, Ivana; Chao, Pen-hsiu Grace; Vunjak-Novakovic, Gordana

    2014-01-01

    Adult articular cartilage is a hypoxic tissue, with oxygen tension ranging from <10% at the cartilage surface to <1% in the deepest layers. In addition to spatial gradients, cartilage development is also associated with temporal changes in oxygen tension. However, a vast majority of cartilage tissue engineering protocols involves cultivation of chondrocytes or their progenitors under ambient oxygen concentration (21% O2), that is, significantly above physiological levels in either developing or adult cartilage. Our study was designed to test the hypothesis that transient hypoxia followed by normoxic conditions results in improved quality of engineered cartilaginous ECM. To this end, we systematically compared the effects of normoxia (21% O2 for 28 days), hypoxia (5% O2 for 28 days) and transient hypoxia—reoxygenation (5% O2 for 7 days and 21% O2 for 21 days) on the matrix composition and expression of the chondrogenic genes in cartilage constructs engineered in vitro. We demonstrated that reoxygenation had the most effect on the expression of cartilaginous genes including COL2A1, ACAN, and SOX9 and increased tissue concentrations of amounts of glycosaminoglycans and type II collagen. The equilibrium Young’s moduli of tissues grown under transient hypoxia (510.01 ± 28.15 kPa) and under normoxic conditions (417.60 ± 68.46 kPa) were significantly higher than those measured under hypoxic conditions (279.61 ± 20.52 kPa). These data suggest that the cultivation protocols utilizing transient hypoxia with reoxygenation have high potential for efficient cartilage tissue engineering, but need further optimization in order to achieve higher mechanical functionality of engineered constructs. PMID:23203946

  13. Understanding fuel anti-knock performances in modern SI engines using fundamental HCCI experiments

    SciTech Connect

    Yang, Yi; Dec, John E.; Sjoberg, Magnus; Ji, Chunsheng

    2015-08-19

    Modern spark-ignition (SI) engine technologies have considerably changed in-cylinder conditions under which fuel autoignition and engine knock take place. In this paper, fundamental HCCI engine experiments are proposed as a means for characterizing the impact of these technologies on the knock propensity of different fuels. In particular, the impacts of turbocharging, direct injection (DI), and downspeeding on operation with ethanol and gasoline are investigated to demonstrate this approach. Results reported earlier for ethanol and gasoline on HCCI combustion are revisited with the new perspective of how their autoignition characteristics fit into the anti-knock requirement in modern SI engines. For example, the weak sensitivity to pressure boost demonstrated by ethanol in HCCI autoignition can be used to explain the strong knock resistance of ethanol fuels for turbocharged SI engines. Further, ethanol's high sensitivity to charge temperature makes charge cooling, which can be produced by fuel vaporization via direct injection or by piston expansion via spark-timing retard, very effective for inhibiting knock. On the other hand, gasoline autoignition shows a higher sensitivity to pressure, so only very low pressure boost can be applied before knock occurs. Gasoline also demonstrates low temperature sensitivity, so it is unable to make as effective use of the charge cooling produced by fuel vaporization or spark retard. These arguments comprehensively explain literature results on ethanol's substantially better anti-knock performance over gasoline in modern turbocharged DISI engines. Fundamental HCCI experiments such as these can thus be used as a diagnostic and predictive tool for knock-limited SI engine performance for various fuels. As a result, examples are presented where HCCI experiments are used to identify biofuel compounds with good potential for modern SI-engine applications.

  14. Understanding fuel anti-knock performances in modern SI engines using fundamental HCCI experiments

    DOE PAGES

    Yang, Yi; Dec, John E.; Sjoberg, Magnus; ...

    2015-08-19

    Modern spark-ignition (SI) engine technologies have considerably changed in-cylinder conditions under which fuel autoignition and engine knock take place. In this paper, fundamental HCCI engine experiments are proposed as a means for characterizing the impact of these technologies on the knock propensity of different fuels. In particular, the impacts of turbocharging, direct injection (DI), and downspeeding on operation with ethanol and gasoline are investigated to demonstrate this approach. Results reported earlier for ethanol and gasoline on HCCI combustion are revisited with the new perspective of how their autoignition characteristics fit into the anti-knock requirement in modern SI engines. For example,more » the weak sensitivity to pressure boost demonstrated by ethanol in HCCI autoignition can be used to explain the strong knock resistance of ethanol fuels for turbocharged SI engines. Further, ethanol's high sensitivity to charge temperature makes charge cooling, which can be produced by fuel vaporization via direct injection or by piston expansion via spark-timing retard, very effective for inhibiting knock. On the other hand, gasoline autoignition shows a higher sensitivity to pressure, so only very low pressure boost can be applied before knock occurs. Gasoline also demonstrates low temperature sensitivity, so it is unable to make as effective use of the charge cooling produced by fuel vaporization or spark retard. These arguments comprehensively explain literature results on ethanol's substantially better anti-knock performance over gasoline in modern turbocharged DISI engines. Fundamental HCCI experiments such as these can thus be used as a diagnostic and predictive tool for knock-limited SI engine performance for various fuels. As a result, examples are presented where HCCI experiments are used to identify biofuel compounds with good potential for modern SI-engine applications.« less

  15. Learning to become graduate students: Japanese women's experience in the research unit in engineering

    NASA Astrophysics Data System (ADS)

    Hosaka, Masako

    2010-12-01

    Based on the analysis of 16 interviews with women first-year master's students at two national engineering schools in Japan, this article examines the socialisation role of compulsory undergraduate research experience in Japanese women's decisions to pursue graduate education and choices of the programme. The findings suggest that research experiences in a small independent research unit within the major department convinced Japanese women engineering students of their academic and social success as graduate students in the current environment. Although participants generally adapted themselves to the research unit through their research, there is a variation in the degree to which they were smoothly integrated into the research unit, reflecting organisational and individual differences.

  16. Design of the exhaust device for light vehicle engine pedestal experiment

    NASA Astrophysics Data System (ADS)

    Sun, Shuguang

    2017-01-01

    In view of the shortcomings and the insufficiency of the existing exhaust device for light vehicle engine pedestal experiment, improvement scheme is proposed to design a suitable multi-type exhaust device for light vehicle engine pedestal experiment, which has flex space and a certain degree of freedom in six directions x, y, z, x, y, z, so the problem of interference during the process of installation can be solved, the cost on research and development and test can be reduced and the development cycle can be shorten and it can also be multi-usage.

  17. Graduate Education. Experiences and Preferences of WES (Waterways Experiment Station) Engineers and Scientists.

    DTIC Science & Technology

    1987-03-01

    processing and % artificial intelligence courses should also be conducted. (020) Advance schedule of courses to be offered - course sequencing. (022) Teach...Random Data .4 Applied Complex Variables (2) Applied Mathematics Artificial Intelligence (3) Asphalt Materials Beach Processes Benthic Ecology...any intelligent engineer or others from a stand- point of improved capabilities. (111) Work hard but also enjoyed the college activities (which

  18. An engineered anisotropic nanofilm with unidirectional wetting properties

    NASA Astrophysics Data System (ADS)

    Malvadkar, Niranjan A.; Hancock, Matthew J.; Sekeroglu, Koray; Dressick, Walter J.; Demirel, Melik C.

    2010-12-01

    Anisotropic textured surfaces allow water striders to walk on water, butterflies to shed water from their wings and plants to trap insects and pollen. Capturing these natural features in biomimetic surfaces is an active area of research. Here, we report an engineered nanofilm, composed of an array of poly(p-xylylene) nanorods, which demonstrates anisotropic wetting behaviour by means of a pin-release droplet ratchet mechanism. Droplet retention forces in the pin and release directions differ by up to 80μN, which is over ten times greater than the values reported for other engineered anisotropic surfaces. The nanofilm provides a microscale smooth surface on which to transport microlitre droplets, and is also relatively easy to synthesize by a bottom-up vapour-phase technique. An accompanying comprehensive model successfully describes the film's anisotropic wetting behaviour as a function of measurable film morphology parameters.

  19. Interfacial Mechanical Properties of Graphene on Self-Assembled Monolayers: Experiments and Simulations.

    PubMed

    Tu, Qing; Kim, Ho Shin; Oweida, Thomas J; Parlak, Zehra; Yingling, Yaroslava G; Zauscher, Stefan

    2017-03-22

    Self-assembled monolayers (SAMs) have been widely used to engineer the electronic properties of substrate-supported graphene devices. However, little is known about how the surface chemistry of SAMs affects the interfacial mechanical properties of graphene supported on SAMs. Fluctuations and changes in these properties affect the stress transfer between substrate and the supported graphene and thus the performance of graphene-based devices. The changes in interfacial mechanical properties can be characterized by measuring the out-of-plane elastic properties. Combining contact resonance atomic force microcopy experiments with molecular dynamics simulations, we show that the head group chemistry of a SAM, which affects the interfacial interactions, can have a significant effect on the out-of-plane elastic modulus of the graphene-SAM heterostructure. Graphene supported on hydrophobic SAMs leads to heterostructures stiffer than those of graphene supported on hydrophilic SAMs, which is largely due to fewer water molecules present at the graphene-SAM interface. Our results provide an important, and often overlooked, insight into the mechanical properties of substrate-supported graphene electronics.

  20. Historic Properties Report: Stratford Army Engine Plant, Connecticut.

    DTIC Science & Technology

    1984-07-01

    Abrams XMl Main Battle Tank. In May 1979 Stratford Division contracted for the first 110 XMI production engines. 2 8 Avco Lycoming also introduced the...helicopter accomplishments see his autobiography The Study of Winged-S; Moran, Aeroplanes Vought, p. 71; Norman Polmar and Floyd D. Kennedy, Jr., Military... Floyd D. Jr. Military Helicopters of the World. Annapolis, Maryland: Naval Institute Press, 1981. Concise guide to historic and contemporary helicopters

  1. Building international experiences into an engineering curriculum - a design project-based approach

    NASA Astrophysics Data System (ADS)

    Maldonado, Victor; Castillo, Luciano; Carbajal, Gerardo; Hajela, Prabhat

    2014-07-01

    This paper is a descriptive account of how short-term international and multicultural experiences can be integrated into early design experiences in an aerospace engineering curriculum. Such approaches are considered as important not only in fostering a student's interest in the engineering curriculum, but also exposing them to a multicultural setting that they are likely to encounter in their professional careers. In the broader sense, this programme is described as a model that can be duplicated in other engineering disciplines as a first-year experience. In this study, undergraduate students from Rensselaer Polytechnic Institute (RPI) and Universidad del Turabo (UT) in Puerto Rico collaborated on a substantial design project consisting of designing, fabricating, and flight-testing radio-controlled model aircraft as a capstone experience in a semester-long course on Fundamentals of Flight. The two-week long experience in Puerto Rico was organised into academic and cultural components designed with the following objectives: (i) to integrate students in a multicultural team-based academic and social environment, (ii) to practise team-building skills and develop students' critical thinking and analytical skills, and finally (iii) to excite students about their engineering major through practical applications of aeronautics and help them decide if it is a right fit for them.

  2. Education of Intellectual Properties for the Training of Creative Engineers

    NASA Astrophysics Data System (ADS)

    Ito, Yoshifumi; Kajiwara, Katuhiko; Oodan, Kyouji

    Kurume National College of Technology has obtained results concerning intellectual property education combined with inventive education. In the education program, students learn about industrial property and practical expertise such as searching the open patents, making up patent-maps, and making patent application papers to the Patent Office under the guidance of a teacher, a patent adviser and attorney. As a result, some of the creative students have already applied for patents. In the future, we are going to prepare a managing system for the intellectual property at our college for the intensification of cooperative application with the local company.

  3. National Educators' Workshop: Update 2002 - Standard Experiments in Engineering, Materials Science, and Technology

    NASA Technical Reports Server (NTRS)

    Prior, Edwin J. (Compiler); Jacobs, James A. (Compiler); Chung, W. Richard (Compiler)

    2003-01-01

    This document contains a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 2002 held in San Jose, California, October 13-16,2002. This publication provides experiments and demonstrations that can serve as a valuable guide to faculty who are interested in useful activities for their students. The material was the result of years of research aimed at better methods of teaching technical subjects. The experiments developed by faculty, scientists, and engineers throughout the United States and abroad add to the collection from past workshops. They include a blend of experiments on new materials and traditional materials.

  4. The impact of program experiences on the retention of women engineering students in Mexico

    NASA Astrophysics Data System (ADS)

    Villa, Maria Del Carmen Garcia

    This qualitative study sought to describe and understand the experiences of female students attending engineering colleges in Mexico and the sources of support and strategies that helped them persist in their programs. The participants were 20 women engineering students enrolled in at least their third year in selected colleges of engineering in Mexico, in both public and private universities, and pursuing a variety of engineering majors. Findings focus on the experiences of female students that helped them stay in their programs. Participants described their experiences in college as very challenging and perceived the environment as hostile and uncertain. In addition, patriarchal Mexican cultural values and stereotypes were identified by students as influencing and helping shape the engineering environment. However, in this context, participants were able to find sources of support and use strategies that helped them remain in their majors, such as a strong desire to succeed, a perceived academic self-ability; and support from their families, peers, institutions, and---most importantly---their professors. Furthermore, the fact that participants were able to persist in their programs gave them a sense of pride and satisfaction that was shared by their families, peers, and faculty. In addition, participants experienced contradictory forces and were constantly negotiating between rejecting traditional gender norms and upholding the norms that are so deeply engrained in Mexican society. Finally, as the students advanced in their programs and became "accepted to the club," they tended to reproduce the male-dominated value system present in engineering colleges accepting their professors' expectations of being "top students," accepting the elitist culture of engineering superiority, and embracing the protection given by their male peers. Retention of Mexican female engineering students is important for all engineering colleges, but cultural factors must be taken into

  5. Laser engineered net shaping (LENS{trademark}) process: Optimization of surface finish and microstructural properties

    SciTech Connect

    Smugeresky, J.E.; Keicher, D.M.; Romero, J.A.; Griffith, M.L.; Harwell, L.D.

    1997-11-01

    Rapid prototyping (RP) has revolutionized the approach to fabricating geometrically complex hardware from a CAD solid model. The various RP techniques allow component designers to directly fabricate conceptual models in plastics and polymer coated metals; however, each of the techniques requires additional processes, e.g. investment casting, to allow the fabrication of functional metallic hardware. This limitation has provided the impetus for further development of solid freeform fabrication technologies which enable fabrication of functional metallic hardware directly from the CAD solid model. The Laser Engineered Net Shaping (LENS{trademark}) process holds promise in satisfying this need. This newly emerging technology possesses the capability to fabricate fully dense components with good dimensional accuracy and with unique materials properties. Relatively complex geometrical shapes have been fabricated using this technology. In continuing to develop the LENS{trademark} process, further advancements are required. The functional dependence of the component surface finish and microstructural characteristics on process parameters including power size and size distribution are being evaluated. A set of statistically designed experiments is being used to sort through the various process parameters and identify significant process variables for improving surface finish and achieving optimum material microstructural properties.

  6. The potential of tissue engineering for developing alternatives to animal experiments: a systematic review.

    PubMed

    de Vries, Rob B M; Leenaars, Marlies; Tra, Joppe; Huijbregtse, Robbertjan; Bongers, Erik; Jansen, John A; Gordijn, Bert; Ritskes-Hoitinga, Merel

    2015-07-01

    An underexposed ethical issue raised by tissue engineering is the use of laboratory animals in tissue engineering research. Even though this research results in suffering and loss of life in animals, tissue engineering also has great potential for the development of alternatives to animal experiments. With the objective of promoting a joint effort of tissue engineers and alternative experts to fully realise this potential, this study provides the first comprehensive overview of the possibilities of using tissue-engineered constructs as a replacement of laboratory animals. Through searches in two large biomedical databases (PubMed, Embase) and several specialised 3R databases, 244 relevant primary scientific articles, published between 1991 and 2011, were identified. By far most articles reviewed related to the use of tissue-engineered skin/epidermis for toxicological applications such as testing for skin irritation. This review article demonstrates, however, that the potential for the development of alternatives also extends to other tissues such as other epithelia and the liver, as well as to other fields of application such as drug screening and basic physiology. This review discusses which impediments need to be overcome to maximise the contributions that the field of tissue engineering can make, through the development of alternative methods, to the reduction of the use and suffering of laboratory animals.

  7. A summary of computational experience at GE Aircraft Engines for complex turbulent flows in gas turbines

    NASA Technical Reports Server (NTRS)

    Zerkle, Ronald D.; Prakash, Chander

    1995-01-01

    This viewgraph presentation summarizes some CFD experience at GE Aircraft Engines for flows in the primary gaspath of a gas turbine engine and in turbine blade cooling passages. It is concluded that application of the standard k-epsilon turbulence model with wall functions is not adequate for accurate CFD simulation of aerodynamic performance and heat transfer in the primary gas path of a gas turbine engine. New models are required in the near-wall region which include more physics than wall functions. The two-layer modeling approach appears attractive because of its computational complexity. In addition, improved CFD simulation of film cooling and turbine blade internal cooling passages will require anisotropic turbulence models. New turbulence models must be practical in order to have a significant impact on the engine design process. A coordinated turbulence modeling effort between NASA centers would be beneficial to the gas turbine industry.

  8. Parts, materials, and processes experience summary, volume 2. [design, engineering, and quality control

    NASA Technical Reports Server (NTRS)

    1973-01-01

    This summary provides the general engineering community with the accumulated experience from ALERT reports issued by NASA and the Government-Industry. Data Exchange Program, and related experience gained by Government and industry. It provides expanded information on selected topics by relating the problem area (failure) to the cause, the investigation and findings, the suggestions for avoidance (inspections, screening tests, proper part applications, requirements for manufacturer's plant facilities, etc.), and failure analysis procedures. Diodes, integrated circuits, and transistors are covered in this volume.

  9. Learning Together? Experiences on a China-U.K. Articulation Program in Engineering

    ERIC Educational Resources Information Center

    Hou, Junxia; McDowell, Liz

    2014-01-01

    This article reports some of the findings of a longitudinal ethnographic research study on the intercultural transition experiences of 50 engineering students in a China-U.K. articulation program. It focuses on the interaction between these students and the U.K.-based cohort, mainly home students. The findings indicate that lack of suitable…

  10. Junior College Teachers of Science, Engineering, and Technology, 1967: Experience and Employment Characteristics.

    ERIC Educational Resources Information Center

    National Science Foundation, Washington, DC.

    This study proposed (1) to determine qualifications and teaching loads of junior college teachers of natural and social sciences, engineering and technology; (2) to examine the courses to identify needed improvements; (3) to determine the status of the profession according to the teacher's experience and his commitment to the junior college.…

  11. Learning to Become Graduate Students: Japanese Women's Experience in the Research Unit in Engineering

    ERIC Educational Resources Information Center

    Hosaka, Masako

    2010-01-01

    Based on the analysis of 16 interviews with women first-year master's students at two national engineering schools in Japan, this article examines the socialisation role of compulsory undergraduate research experience in Japanese women's decisions to pursue graduate education and choices of the programme. The findings suggest that research…

  12. Classroom Experiences in an Engineering Design Graphics Course with a CAD/CAM Extension.

    ERIC Educational Resources Information Center

    Barr, Ronald E.; Juricic, Davor

    1997-01-01

    Reports on the development of a new CAD/CAM laboratory experience for an Engineering Design Graphics (EDG) course. The EDG curriculum included freehand sketching, introduction to Computer-Aided Design and Drafting (CADD), and emphasized 3-D solid modeling. Reviews the project and reports on the testing of the new laboratory components which were…

  13. Applying Peer Reviews in Software Engineering Education: An Experiment and Lessons Learned

    ERIC Educational Resources Information Center

    Garousi, V.

    2010-01-01

    Based on the demonstrated value of peer reviews in the engineering industry, numerous industry experts have listed it at the top of the list of desirable development practices. Experience has shown that problems (defects) are eliminated earlier if a development process incorporates peer reviews and that these reviews are as effective as or even…

  14. Multi-Partner Experiment to Test Volcanic-Ash Ingestion by a Jet Engine

    NASA Technical Reports Server (NTRS)

    Lekki, John; Lyall, Eric; Guffanti, Marianne; Fisher, John; Erlund, Beth; Clarkson, Rory; van de Wall, Allan

    2013-01-01

    A research team of U.S. Government agencies and engine manufacturers are designing an experiment to test volcanic-ash ingestion by a NASA owned F117 engine that was donated by the U.S. Air Force. The experiment is being conducted under the auspices of NASA s Vehicle Integrated Propulsion Research (VIPR) Program and will take place in early 2014 at Edwards AFB in California as an on-ground, on-wing test. The primary objectives are to determine the effect on the engine of several hours of exposure to low to moderate ash concentrations, currently proposed at 1 and 10 mg/m3 and to evaluate the capability of engine health management technologies for detecting these effects. A natural volcanic ash will be used that is representative of distal ash clouds many 100's to approximately 1000 km from a volcanic source i.e., the ash should be composed of fresh glassy particles a few tens of microns in size. The glassy ash particles are expected to soften and become less viscous when exposed to the high temperatures of the combustion chamber, then stick to the nozzle guide vanes of the high-pressure turbine. Numerous observations and measurements of the engine s performance and degradation will be made during the course of the experiment, including borescope and tear-down inspections. While not intended to be sufficient for rigorous certification of engine performance when ash is ingested, the experiment should provide useful information to aircraft manufacturers, airline operators, and military and civil regulators in their efforts to evaluate the range of risks that ash hazards pose to aviation.

  15. Experiments in a Deep Underground Science and Engineering Laboratory (DUSEL) Hosted in Sedimentary Rocks

    NASA Astrophysics Data System (ADS)

    Burbey, T. J.; Kimballton, M. O.; Science Team

    2004-12-01

    Sedimentary-rock environments, particularly those dominated by carbonate rock, provide unique opportunities for geoscientists, geobiologists, and geophysicists, to perform revolutionary experiments aimed at answering fundamental science questions and satisfying our societal demands for resources and environmental stewardship. As part of the National Science Foundation's DUSEL initiative, the selected site should offer structurally and biologically diverse environments. At the same time, the site should offer host rock capable of providing safely engineered hallways and laboratories at depths as great as 2,200 m for numerous deep underground physics, engineering, and earth science experiments. An ideal sedimentary-rock environment offers the prospect of highly folded, thrusted, and fractured rocks that allow opportunities to study the 3-D behavior of thrusts that propagate parallel to bedding as well as those that ramp across bedding. Flow dynamics along and across deeply buried faults is poorly understood. Experiments will be developed at various scales to assess flow and transport processes to better quantify hydrogeological mechanisms influencing flow and possible aquifer compartmentalization. Seismic reflection images, vertical seismic profiles, and tomograms will provide details of the fault properties and geometry, which can be verified in-situ. Repeated overthrusted sequences provide opportunities for geobiologists to investigate how microbes in rocks of similar age are affected by differences in pressure, temperature, and depth. Carbonate rocks provide opportunities to study energy sources and adaptations for nutrient acquisition, reproduction, stability, survival, and repair under extreme conditions. Results from these investigations will permit comparisons with other foreland fold-thrust belts worldwide. Fossil fuels remain the world's main energy resource and the large majority of these are hosted in sedimentary rocks. Improved methods for reservoir

  16. Campus Climate and the Underrepresented Minority Engineering Student Experience: A Critical Race Study

    NASA Astrophysics Data System (ADS)

    Mayes, Terrance

    In the current technological era, the number of minorities in science, technology, engineering, and mathematics (STEM) is a crucial factor in predetermining the economic growth of the United States. Since the minority population is growing at much faster rates than the non-minority population, the lack of proportionate production of minority engineers poses a threat to the United States' ability to remain a global competitor in technological innovation. Sixty-three per cent (63%) of undergraduate students who enter engineering majors continue on to graduate in that major. The graduation rate, however, for African-American, Hispanic, and Native-American students in engineering is significantly lower at 39%. As this group represents only a small fraction of the annual student enrollment, engineering programs are graduating these minority groups at rates that are greatly disproportionate to United States demographics. Therefore, researchers are thoroughly investigating certain initiatives that promote academic success among underrepresented minority students in engineering. Colleges and universities have attempted to address the growing achievement gap between underrepresented minority and non-minority engineering students, predominately through various deficit-based interventions, focusing on the student's flaws and problems. As the pipeline for minorities in engineering continues to narrow, it begs the question of whether institutions are focusing on the right solutions to the problem. Critical Race Theory scholars argue that colleges and universities must address institutional climate issues around students, such as racism, microaggressions, and marginalization, before members of oppressed groups can truly succeed. This dissertation explored the unique experiences of underrepresented minority engineering students in a predominately White and Asian campus.

  17. Bioinspired Reductionistic Peptide Engineering for Exceptional Mechanical Properties.

    PubMed

    Avinash, M B; Raut, Devaraj; Mishra, Manish Kumar; Ramamurty, Upadrasta; Govindaraju, T

    2015-11-03

    A simple solution-processing and self-assembly approach that exploits the synergistic interactions between multiple hydrogen bonded networks and aromatic interactions was utilized to synthesize molecular crystals of cyclic dipeptides (CDPs), whose molecular weights (~0.2 kDa) are nearly three orders of magnitude smaller than that of natural structural proteins (50-300 kDa). Mechanical properties of these materials, measured using the nanoindentation technique, indicate that the stiffness and strength are comparable and sometimes better than those of natural fibres. The measured mechanical responses were rationalized by recourse to the crystallographic structural analysis and intermolecular interactions in the self-assembled single crystals. With this work we highlight the significance of developing small molecule based bioinspired design strategies to emulate biomechanical properties. A particular advantage of the successfully demonstrated reductionistic strategy of the present work is its amenability for realistic industrial scale manufacturing of designer biomaterials with desired mechanical properties.

  18. Bioinspired Reductionistic Peptide Engineering for Exceptional Mechanical Properties

    PubMed Central

    Avinash, M. B.; Raut, Devaraj; Mishra, Manish Kumar; Ramamurty, Upadrasta; Govindaraju, T.

    2015-01-01

    A simple solution-processing and self-assembly approach that exploits the synergistic interactions between multiple hydrogen bonded networks and aromatic interactions was utilized to synthesize molecular crystals of cyclic dipeptides (CDPs), whose molecular weights (~0.2 kDa) are nearly three orders of magnitude smaller than that of natural structural proteins (50–300 kDa). Mechanical properties of these materials, measured using the nanoindentation technique, indicate that the stiffness and strength are comparable and sometimes better than those of natural fibres. The measured mechanical responses were rationalized by recourse to the crystallographic structural analysis and intermolecular interactions in the self-assembled single crystals. With this work we highlight the significance of developing small molecule based bioinspired design strategies to emulate biomechanical properties. A particular advantage of the successfully demonstrated reductionistic strategy of the present work is its amenability for realistic industrial scale manufacturing of designer biomaterials with desired mechanical properties. PMID:26525957

  19. Bioinspired Reductionistic Peptide Engineering for Exceptional Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Avinash, M. B.; Raut, Devaraj; Mishra, Manish Kumar; Ramamurty, Upadrasta; Govindaraju, T.

    2015-11-01

    A simple solution-processing and self-assembly approach that exploits the synergistic interactions between multiple hydrogen bonded networks and aromatic interactions was utilized to synthesize molecular crystals of cyclic dipeptides (CDPs), whose molecular weights (~0.2 kDa) are nearly three orders of magnitude smaller than that of natural structural proteins (50-300 kDa). Mechanical properties of these materials, measured using the nanoindentation technique, indicate that the stiffness and strength are comparable and sometimes better than those of natural fibres. The measured mechanical responses were rationalized by recourse to the crystallographic structural analysis and intermolecular interactions in the self-assembled single crystals. With this work we highlight the significance of developing small molecule based bioinspired design strategies to emulate biomechanical properties. A particular advantage of the successfully demonstrated reductionistic strategy of the present work is its amenability for realistic industrial scale manufacturing of designer biomaterials with desired mechanical properties.

  20. Physical and Biological Properties of Engineered Protein Hydrogels

    NASA Astrophysics Data System (ADS)

    Tirrell, David

    2012-02-01

    Injectable hydrogels show substantial promise for use in minimally invasive tissue engineering and drug delivery procedures. A new injectable hydrogel material, developed from recombinant telechelic proteins expressed in E. coli, demonstrates shear thinning by three orders of magnitude at large strains. Large amplitude oscillatory shear illustrates that shear thinning is due to yielding within the bulk of the gel, and the rheological response and flow profiles are consistent with a shear-banding mechanism for yielding. The sharp yielding transition and large magnitude of the apparent shear thinning allow gels to be injected through narrow gauge needles with only gentle hand pressure. After injection the gels reset to full elastic strength in seconds due to rapid reformation of the physical network junctions, allowing self-supporting structures to be formed. The shear thinning behavior is largely independent of the midblock length, enabling genetic engineering to be used to control the equilibrium modulus of the gel without loss of the characteristic yielding behavior. The shear-banding mechanism localizes shear stresses during flow into narrow regions of the gel, allowing more than 95% of seeded cells to survive the injection process.

  1. Structure and Electronic Properties of Cerium Orthophosphate: Theory and Experiment

    SciTech Connect

    Adelstein, Nicole; Mun, B. Simon; Ray, Hannah; Ross Jr, Phillip; Neaton, Jeffrey; De Jonghe, Lutgard

    2010-07-27

    Structural and electronic properties of cerium orthophosphate (CePO{sub 4}) are calculated using density functional theory (DFT) with the local spin-density approximation (LSDA+U), with and without gradient corrections (GGA-(PBE)+U), and compared to X-ray diffraction and photoemission spectroscopy measurements. The density of states is found to change significantly as the Hubbard parameter U, which is applied to the Ce 4f states, is varied from 0 to 5 eV. The calculated structural properties are in good agreement with experiment and do not change significantly with U. Choosing U = 3 eV for LDSA provides the best agreement between the calculated density of states and the experimental photoemission spectra.

  2. Appolonian Packing and Fractal Shape of Grains Improving Geomechanical Properties in Engineering Geology

    NASA Astrophysics Data System (ADS)

    Hecht, C. A.

    Fractal packing and highly irregular shaped particles increase the mechanical properties of rocks and building materials. This suggests that fractal methods are good tools for modeling particle mixes with efficient properties like maximum strength and maximum surface area or minimum porosity and minimum permeability. However gradings and packings are calculated by ``Euclidean'' disk models and sphere models. Surprisingly even the simplest models are far more complex than they appear. The fractal ``Appolonian packing model'' is proposed as the most universal two-dimensional packing model. However the inhomogeneity of gradings and the irregularity of natural grain shapes and surfaces are not reflected by these models. Consequently calculations are often far from empirical observations and experimental results. A thorough quantification of packings and gradings is important for many reasons and still a matter of intense investigation and controversial discussion. This study concentrates on fractal models for densely packed non-cohesive rocks, crushed mineral assemblages, concrete and asphalt mixtures. A summary of fractal grain size distributions with linear cumulative curves on log-log plots is presented for these mixtures. It is shown that fractal two-dimensional and three-dimensional models for dense packings reflect different physical processes of material mixing or geological deposition. The results from shear-box experiments on materials with distinct grain size distributions show a remarkable increase of the mechanical strength from non-fractal to fractal mixtures. It is suggested that fractal techniques need more systematical application and correlation with results from material testing experiments in engineering geology. The purpose of future work should lead towards the computability of dense packings of angular particles in three dimensions.

  3. Engineering Biomaterial Properties for Central Nervous System Applications

    NASA Astrophysics Data System (ADS)

    Rivet, Christopher John

    Biomaterials offer unique properties that are intrinsic to the chemistry of the material itself or occur as a result of the fabrication process; iron oxide nanoparticles are superparamagnetic, which enables controlled heating in the presence of an alternating magnetic field, and a hydrogel and electrospun fiber hybrid material provides minimally invasive placement of a fibrous, artificial extracellular matrix for tissue regeneration. Utilization of these unique properties towards central nervous system disease and dysfunction requires a thorough definition of the properties in concert with full biological assessment. This enables development of material-specific features to elicit unique cellular responses. Iron oxide nanoparticles are first investigated for material-dependent, cortical neuron cytotoxicity in vitro and subsequently evaluated for alternating magnetic field stimulation induced hyperthermia, emulating the clinical application for enhanced chemotherapy efficacy in glioblastoma treatment. A hydrogel and electrospun fiber hybrid material is first applied to a rat brain to evaluate biomaterial interface astrocyte accumulation as a function of hybrid material composition. The hybrid material is then utilized towards increasing functional engraftment of dopaminergic progenitor neural stem cells in a mouse model of Parkinson's disease. Taken together, these two scenarios display the role of material property characterization in development of biomaterial strategies for central nervous system repair and regeneration.

  4. Identification and quantification analysis of nonlinear dynamics properties of combustion instability in a diesel engine.

    PubMed

    Yang, Li-Ping; Ding, Shun-Liang; Litak, Grzegorz; Song, En-Zhe; Ma, Xiu-Zhen

    2015-01-01

    The cycling combustion instabilities in a diesel engine have been analyzed based on chaos theory. The objective was to investigate the dynamical characteristics of combustion in diesel engine. In this study, experiments were performed under the entire operating range of a diesel engine (the engine speed was changed from 600 to 1400 rpm and the engine load rate was from 0% to 100%), and acquired real-time series of in-cylinder combustion pressure using a piezoelectric transducer installed on the cylinder head. Several methods were applied to identify and quantitatively analyze the combustion process complexity in the diesel engine including delay-coordinate embedding, recurrence plot (RP), Recurrence Quantification Analysis, correlation dimension (CD), and the largest Lyapunov exponent (LLE) estimation. The results show that the combustion process exhibits some determinism. If LLE is positive, then the combustion system has a fractal dimension and CD is no more than 1.6 and within the diesel engine operating range. We have concluded that the combustion system of diesel engine is a low-dimensional chaotic system and the maximum values of CD and LLE occur at the lowest engine speed and load. This means that combustion system is more complex and sensitive to initial conditions and that poor combustion quality leads to the decrease of fuel economy and the increase of exhaust emissions.

  5. Identification and quantification analysis of nonlinear dynamics properties of combustion instability in a diesel engine

    SciTech Connect

    Yang, Li-Ping Ding, Shun-Liang; Song, En-Zhe; Ma, Xiu-Zhen; Litak, Grzegorz

    2015-01-15

    The cycling combustion instabilities in a diesel engine have been analyzed based on chaos theory. The objective was to investigate the dynamical characteristics of combustion in diesel engine. In this study, experiments were performed under the entire operating range of a diesel engine (the engine speed was changed from 600 to 1400 rpm and the engine load rate was from 0% to 100%), and acquired real-time series of in-cylinder combustion pressure using a piezoelectric transducer installed on the cylinder head. Several methods were applied to identify and quantitatively analyze the combustion process complexity in the diesel engine including delay-coordinate embedding, recurrence plot (RP), Recurrence Quantification Analysis, correlation dimension (CD), and the largest Lyapunov exponent (LLE) estimation. The results show that the combustion process exhibits some determinism. If LLE is positive, then the combustion system has a fractal dimension and CD is no more than 1.6 and within the diesel engine operating range. We have concluded that the combustion system of diesel engine is a low-dimensional chaotic system and the maximum values of CD and LLE occur at the lowest engine speed and load. This means that combustion system is more complex and sensitive to initial conditions and that poor combustion quality leads to the decrease of fuel economy and the increase of exhaust emissions.

  6. Science Data Report for the Optical Properties Monitor (OPM) Experiment

    NASA Technical Reports Server (NTRS)

    Wilkes, D. R.; Zwiener, J. M.; Carruth, Ralph (Technical Monitor)

    2001-01-01

    This science data report describes the Optical Properties Monitor (OPM) experiment and the data gathered during its 9-mo exposure on the Mir space station. Three independent optical instruments made up OPM: an integrating sphere spectral reflectometer, vacuum ultraviolet spectrometer, and a total integrated scatter instrument. Selected materials were exposed to the low-Earth orbit, and their performance monitored in situ by the OPM instruments. Coinvestigators from four NASA Centers, five International Space Station contractors, one university, two Department of Defense organizations, and the Russian space company, Energia, contributed samples to this experiment. These materials included a number of thermal control coatings, optical materials, polymeric films, nanocomposites, and other state-of-the-art materials. Degradation of some materials, including aluminum conversion coatings and Beta cloth, was greater than expected. The OPM experiment was launched aboard the Space Shuttle on mission STS-81 in January 1997 and transferred to the Mir space station. An extravehicular activity (EVA) was performed in April 1997 to attach the OPM experiment to the outside of the Mir/Shuttle Docking Module for space environment exposure. OPM was retrieved during an EVA in January 1998 and was returned to Earth on board the Space Shuttle on mission STS-89.

  7. Quantitative Ultrasonic Evaluation of Mechanical Properties of Engineering Materials

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1978-01-01

    Progress in the application of ultrasonic techniques to nondestructive measurement of mechanical strength of engineering materials is reviewed. A dormant concept in nondestructive evaluation (NDE) is invoked. The availability of ultrasonic methods that can be applied to actual parts to assess their potential susceptibility to failure under design conditions is discussed. It was shown that ultrasonic methods yield measurements of elastic moduli, microstructure, hardness, fracture toughness, tensile strength, yield strength, and shear strength for a wide range of materials (including many types of metals, ceramics, and fiber composites). It was also indicated that although most of these methods were shown feasible in laboratory studies, more work is needed before they can be used on actual parts in processing, assembly, inspection, and maintenance lines.

  8. A phenomenographic analysis of first-year engineering students' experiences with problems involving multiple possible solutions

    NASA Astrophysics Data System (ADS)

    Dringenberg, Emily A.

    Engineers are expected to solve problems that are ill-structured. These problems are presented with a lack of necessary information and allow for different ways of engaging with the problem; they are open-ended and involve multiple possible solutions with multiple means of evaluation. In order to allow maximum time for students to develop skills for solving such problems, undergraduate engineering programs can introduce such problems during the first year of students' education, in the form of cornerstone design tasks. This provides students with more opportunities to develop their ability to engage with ill-structured problems, which are characteristic of engineering work. Researchers have documented variation within both the behavior and perceptions of students' early experiences with design problems. General themes include novice-like design behavior, discomfort with lack of information, difficulty with problem scoping, and resistance to ambiguity. To build on these generalizations of students' experiences, a more thorough understanding of the variation in how students experience this phenomenon of engaging with ill-structured problems is needed to design effective learning environments. This work presents the qualitatively different ways that engineering students experience problems with multiple possible solutions during their first year of engineering studies. Using phenomenography as the methodological framework, data were collected through in-depth, semi-structured interviews with 27 first-year engineering students. The iterative, phenomenographic analysis resulted in seven descriptive categories for the ways participants experienced problems involving multiple possible solutions. The names of these categories represent the different foci of the students' experiences: completion, transition, iteration, organization, collaboration, reasoning, and growth. These categories are organized along two crucial dimensions of variation: reaction to ambiguity and role

  9. Rational engineering of physicochemical properties of nanomaterials for biomedical applications with nanotoxicological perspectives

    NASA Astrophysics Data System (ADS)

    Navya, P. N.; Daima, Hemant Kumar

    2016-02-01

    Innovative engineered nanomaterials are at the leading edge of rapidly emerging fields of nanobiotechnology and nanomedicine. Meticulous synthesis, unique physicochemical properties, manifestation of chemical or biological moieties on the surface of materials make engineered nanostructures suitable for a variety of biomedical applications. Besides, tailored nanomaterials exhibit entirely novel therapeutic applications with better functionality, sensitivity, efficiency and specificity due to their customized unique physicochemical and surface properties. Additionally, such designer made nanomaterials has potential to generate series of interactions with various biological entities including DNA, proteins, membranes, cells and organelles at nano-bio interface. These nano-bio interactions are driven by colloidal forces and predominantly depend on the dynamic physicochemical and surface properties of nanomaterials. Nevertheless, recent development and atomic scale tailoring of various physical, chemical and surface properties of nanomaterials is promising to dictate their interaction in anticipated manner with biological entities for biomedical applications. As a result, rationally designed nanomaterials are in extensive demand for bio-molecular detection and diagnostics, therapeutics, drug and gene delivery, fluorescent labelling, tissue engineering, biochemical sensing and other pharmaceuticals applications. However, toxicity and risk associated with engineered nanomaterials is rather unclear or not well understood; which is gaining considerable attention and the field of nanotoxicology is evolving promptly. Therefore, this review explores current knowledge of articulate engineering of nanomaterials for biomedical applications with special attention on potential toxicological perspectives.

  10. Rational engineering of physicochemical properties of nanomaterials for biomedical applications with nanotoxicological perspectives.

    PubMed

    Navya, P N; Daima, Hemant Kumar

    2016-01-01

    Innovative engineered nanomaterials are at the leading edge of rapidly emerging fields of nanobiotechnology and nanomedicine. Meticulous synthesis, unique physicochemical properties, manifestation of chemical or biological moieties on the surface of materials make engineered nanostructures suitable for a variety of biomedical applications. Besides, tailored nanomaterials exhibit entirely novel therapeutic applications with better functionality, sensitivity, efficiency and specificity due to their customized unique physicochemical and surface properties. Additionally, such designer made nanomaterials has potential to generate series of interactions with various biological entities including DNA, proteins, membranes, cells and organelles at nano-bio interface. These nano-bio interactions are driven by colloidal forces and predominantly depend on the dynamic physicochemical and surface properties of nanomaterials. Nevertheless, recent development and atomic scale tailoring of various physical, chemical and surface properties of nanomaterials is promising to dictate their interaction in anticipated manner with biological entities for biomedical applications. As a result, rationally designed nanomaterials are in extensive demand for bio-molecular detection and diagnostics, therapeutics, drug and gene delivery, fluorescent labelling, tissue engineering, biochemical sensing and other pharmaceuticals applications. However, toxicity and risk associated with engineered nanomaterials is rather unclear or not well understood; which is gaining considerable attention and the field of nanotoxicology is evolving promptly. Therefore, this review explores current knowledge of articulate engineering of nanomaterials for biomedical applications with special attention on potential toxicological perspectives.

  11. Project Palanquin. Preshot Geologic and Engineering Properties Investigations

    DTIC Science & Technology

    1968-10-11

    formation. The uppermost flow of this formation is porphyritic trachyte , which is at least 351 feet thick beneath the site. The Ribbon Cliff formation is... trachyte is severely altered and decomposed within zones of intense fractur- ing related to faulting. Subsurface data indicate the presence of a high-angle...property values of the porphyritic trachyte are as follows: dry bulk specific gravity, 2.49; dry bulk density, 155 pcf; static unconfined compressive

  12. Aircraft Turbine Engine Monitoring Experience: An Overview and Lessons Learned from Selected Case Studies.

    DTIC Science & Technology

    1980-08-01

    Engines DMMH/FH 1.12 0.80 Removal rate/1000 hr 1.74 1.85 The OPTEVFOR analysis was limited on several counts: (1) The evaluation failed to consider or...investigate aircraft turbine engine monitoring experience. Conducted under the Project AIR FORCE project, "Methods and Applications of Life-Cycle Analysis for...for hot-section parts; o Hot-section parts vary in age and accumulated creep ; o Other failure modes (low cycle fatigue , thermal shock, etc.) were

  13. Preliminary experiments on active control of fan noise from a turbofan engine

    NASA Technical Reports Server (NTRS)

    Thomas, R. H.; Burdisso, R. A.; Fuller, C. R.; O'Brien, W. F.

    1993-01-01

    In the preliminary experiments reported here, active acoustic sources positioned around the circumference of a turbofan engine were used to control the fan noise radiated forward through the inlet. The main objective was to demonstrate the potential of active techniques to alleviate the noise pollution that will be produced by the next generation of larger engines. A reduction of up to 19 dB in the radiation directivity was demonstrated in a zone that encompasses a 30-deg angle, near the error sensor, while spillover effects were observed toward the lateral direction. The simultaneous control of two tones was also demonstrated using two identical controllers in a parallel control configuration.

  14. A thermodynamic approach to obtain materials properties for engineering applications

    NASA Technical Reports Server (NTRS)

    Chang, Y. Austin

    1993-01-01

    With the ever increases in the capabilities of computers for numerical computations, we are on the verge of using these tools to model manufacturing processes for improving the efficiency of these processes as well as the quality of the products. One such process is casting for the production of metals. However, in order to model metal casting processes in a meaningful way it is essential to have the basic properties of these materials in their molten state, solid state as well as in the mixed state of solid and liquid. Some of the properties needed may be considered as intrinsic such as the density, heat capacity or enthalpy of freezing of a pure metal, while others are not. For instance, the enthalpy of solidification of an alloy is not a defined thermodynamic quantity. Its value depends on the micro-segregation of the phases during the course of solidification. The objective of the present study is to present a thermodynamic approach to obtain some of the intrinsic properties and combining thermodynamics with kinetic models to estimate such quantities as the enthalpy of solidification of an alloy.

  15. Simulation and experiment for oxygen-enriched combustion engine using liquid oxygen to solidify CO2

    NASA Astrophysics Data System (ADS)

    Liu, Yongfeng; Jia, Xiaoshe; Pei, Pucheng; Lu, Yong; Yi, Li; Shi, Yan

    2016-01-01

    For capturing and recycling of CO2 in the internal combustion engine, Rankle cycle engine can reduce the exhaust pollutants effectively under the condition of ensuring the engine thermal efficiency by using the techniques of spraying water in the cylinder and optimizing the ignition advance angle. However, due to the water spray nozzle need to be installed on the cylinder, which increases the cylinder head design difficulty and makes the combustion conditions become more complicated. In this paper, a new method is presented to carry out the closing inlet and exhaust system for internal combustion engines. The proposed new method uses liquid oxygen to solidify part of cooled CO2 from exhaust system into dry ice and the liquid oxygen turns into gas oxygen which is sent to inlet system. The other part of CO2 is sent to inlet system and mixed with oxygen, which can reduce the oxygen-enriched combustion detonation tendency and make combustion stable. Computing grid of the IP52FMI single-cylinder four-stroke gasoline-engine is established according to the actual shape of the combustion chamber using KIVA-3V program. The effects of exhaust gas recirculation (EGR) rate are analyzed on the temperatures, the pressures and the instantaneous heat release rates when the EGR rate is more than 8%. The possibility of enclosing intake and exhaust system for engine is verified. The carbon dioxide trapping device is designed and the IP52FMI engine is transformed and the CO2 capture experiment is carried out. The experimental results show that when the EGR rate is 36% for the optimum EGR rate. When the liquid oxygen of 35.80-437.40 g is imported into the device and last 1-20 min, respectively, 21.50-701.30 g dry ice is obtained. This research proposes a new design method which can capture CO2 for vehicular internal combustion engine.

  16. Transient Mathematical Modeling for Liquid Rocket Engine Systems: Methods, Capabilities, and Experience

    NASA Technical Reports Server (NTRS)

    Martin, Michael A.; Nguyen, Huy H.; Greene, William D.; Seymout, David C.

    2003-01-01

    The subject of mathematical modeling of the transient operation of liquid rocket engines is presented in overview form from the perspective of engineers working at the NASA Marshall Space Flight Center. The necessity of creating and utilizing accurate mathematical models as part of liquid rocket engine development process has become well established and is likely to increase in importance in the future. The issues of design considerations for transient operation, development testing, and failure scenario simulation are discussed. An overview of the derivation of the basic governing equations is presented along with a discussion of computational and numerical issues associated with the implementation of these equations in computer codes. Also, work in the field of generating usable fluid property tables is presented along with an overview of efforts to be undertaken in the future to improve the tools use for the mathematical modeling process.

  17. Transient Mathematical Modeling for Liquid Rocket Engine Systems: Methods, Capabilities, and Experience

    NASA Technical Reports Server (NTRS)

    Seymour, David C.; Martin, Michael A.; Nguyen, Huy H.; Greene, William D.

    2005-01-01

    The subject of mathematical modeling of the transient operation of liquid rocket engines is presented in overview form from the perspective of engineers working at the NASA Marshall Space Flight Center. The necessity of creating and utilizing accurate mathematical models as part of liquid rocket engine development process has become well established and is likely to increase in importance in the future. The issues of design considerations for transient operation, development testing, and failure scenario simulation are discussed. An overview of the derivation of the basic governing equations is presented along with a discussion of computational and numerical issues associated with the implementation of these equations in computer codes. Also, work in the field of generating usable fluid property tables is presented along with an overview of efforts to be undertaken in the future to improve the tools use for the mathematical modeling process.

  18. Challenges in Obtaining Property Access: The FUSRAP Maywood Site Experience - 13433

    SciTech Connect

    Kollar, William

    2013-07-01

    The Formerly Utilized Sites Remedial Action Program (FUSRAP) is the US government program started in 1974 to identify, investigate and clean up or control sites that became contaminated as a result of the nation's early atomic programs. Many of these sites are not owned by the federal government and therefore require owner permission to enter. The experience in pursuing such access at the FUSRAP Maywood Superfund Site (the Maywood Site or the Site) in Bergen County, New Jersey, is extensive. Since the US Army Corps of Engineers (the Corps) assumed responsibility for the Maywood Site from the US Department of Energy in 1997, at least 186 separate property access agreements (known in FUSRAP as a Real Estate Right-of- Entry or ROE) have been executed between the Corps and approximately 55 different land owners and tenant occupants at the Maywood Site (agreement renewals with the same owners over time account for the difference). Maywood's experience during the Corps' tenure, reflected here in three case studies of representative property access efforts, offers some lessons and best practices that may apply to other remedial programs. While the Site Community Relations Manager (the author of this paper) managed the property access task, multi-disciplinary support from across the project was also critical to success in this endeavor. (authors)

  19. Epoxy adhesive formulations for engineered wood manufacturing: Design of Experiment (DOE) and hardener modification

    NASA Astrophysics Data System (ADS)

    Wangkheeree, W.; Meekum, U.

    2016-03-01

    The effect of IPDA, DDS, BPA and DICY, as main ingredient of TETA based hardener were examined. The 2k design of experiment(DOE) with k=3 were preliminary explored. The designed parameters A(IPDA), B(DDS) and C(BPA) were assigned as low(-) and high(+) levels, respectively. The Design Expert™ was hired as the analyzing tool at α=0.05. The mixed epoxy resin was based on the commercial one. The designed responds including tcure, t50, impact strengths, flexural properties and HDT were measured, respectively. Regarding to ANOVA conclusion, it was found that, there were no significant effects on the assigned parameters on the interested responds, except for the HDT where BPA(C) was negative effect was found. The lower in the crosslink density of cured epoxy, inferior in HDT, the higher in BPA addition was hypothesized. It was found that impact strength of cured epoxy derived from all formula were unacceptable low and tcure and t50, were too short. Thus, the further investigation by adding DICY into hardener was explored. The results showed that no significant change by mechanical means of cured epoxy by resolving 5-30 phr of DICY into the hardener. However, it was observed that the DICY added formula showed the obvious long cure times and behave as prepreg formula. The room temperature cured epoxy was incompletely crosslinked. The degrees of linear chain fragment were evidence, by weight, when higher DICY loading was engaged. Complete crosslink was achieved at 150°C post curing. The hardener comprised of TETA/aliphatic Epoxy(RD108) adduct was studied for enhancing the toughness of epoxy resin. It was observed that longer cure time at 150°C but lower toughness was experienced, on both prepreg and engineered wood made from the resins, at high TETA/RD108 ratio. Incomplete cure was explained for the mechanical inferior at high RD108 loading.

  20. Experiments on the thermoelectric properties of quantum dots

    NASA Astrophysics Data System (ADS)

    Svilans, Artis; Leijnse, Martin; Linke, Heiner

    2016-12-01

    Quantum dots (QDs) are good model systems for fundamental studies of mesoscopic transport phenomena using thermoelectric effects because of their small size, electrostatically tunable properties and thermoelectric response characteristics that are very sensitive to small thermal biases. Here we provide a review of experimental studies on thermoelectric properties of single QDs realized in two-dimensional electron gases, single-walled carbon nanotubes and semiconductor nanowires. A key requirement for such experiments is to have some methods for nanoscale thermal biasing at one's disposal. We briefly review the main techniques used in the field, namely, heating of the QD contacts, side heating and top heating, and touch upon their relative advantages. The thermoelectric response of a QD as a function of gate potential has a characteristic oscillatory behavior with the same period as is observed for conductance peaks. Much of the existing literature focuses on the agreement between experiments and theory, particularly for amplitude and line-shape of the thermovoltage Vth. A general observation is that the widely used single-electron tunneling approximation for QDs has limited success in reproducing measured Vth. Landauer-type calculations are often found to describe measurement results better, despite the large electron-electron interactions in QDs. More recently, nonlinear thermoelectric effects have moved into the focus of attention, and we offer a brief overview of the experiments done so far. We conclude by discussing open questions and avenues for future work, including the role of asymmetries in tunnel- and capacitive couplings in the thermoelectric behavior of QDs. xml:lang="fr"

  1. Engineering Database of Liquid Salt Thermophysical and Thermochemical Properties

    SciTech Connect

    Manohar S. Sohal; Matthias A. Ebner; Piyush Sabharwall; Phil Sharpe

    2010-03-01

    The purpose of this report is to provide a review of thermodynamic and thermophysical properties of candidate molten salt coolants, which may be used as a primary coolant within a nuclear reactor or heat transport medium from the Next Generation Nuclear Plant (NGNP) to a processing plant, for example, a hydrogen-production plant. Thermodynamic properties of four types of molten salts, including LiF-BeF2 (67 and 33 mol%, respectively; also known as FLiBe), LiF-NaF-KF (46.5, 11.5, and 52 mol%, also known as FLiNaK), and KCl-MgCl2 (67 and 33 mol%), and sodium nitrate-sodium nitrite-potassium nitrate (NaNO3–NaNO2–KNO3, (7-49-44 or 7-40-53 mol%) have been investigated. Limitations of existing correlations to predict density, viscosity, specific heat capacity, surface tension, and thermal conductivity, were identified. The impact of thermodynamic properties on the heat transfer, especially Nusselt number was also discussed. Stability of the molten salts with structural alloys and their compatibility with the structural alloys was studied. Nickel and alloys with dense Ni coatings are effectively inert to corrosion in fluorides but not so in chlorides. Of the chromium containing alloys, Hastelloy N appears to have the best corrosion resistance in fluorides, while Haynes 230 was most resistant in chloride. In general, alloys with increasing carbon and chromium content are increasingly subject to corrosion by the fluoride salts FLiBe and FLiNaK, due to attack and dissolution of the intergranular chromium carbide. Future research to obtain needed information was identified.

  2. Science Data Report for the Optical Properties Monitor (OPM) Experiment

    NASA Technical Reports Server (NTRS)

    Wilkes, Donald R.; Zwiener, James M.

    1999-01-01

    Long term stability of spacecraft materials when exposed to the space environment continues to be a major area of investigation. The natural and induced environment surrounding a spacecraft can decrease material performance and limit useful lifetimes. The Optical Properties Monitor (OPM) experiment provided the capability to perform the important flight testing of materials and was flown on the Russian Mir Station to study the long term effects of the natural and induced space environment on materials. The core of the OPM in-flight analysis was three independent optical instruments. These instruments included an integrating sphere spectral reflectometer, a vacuum ultraviolet spectrometer, and a Total Integrated Scatter instrument. The OPM also monitored selected components of the environment including molecular contamination. The OPM was exposed on the exterior of the Mir Docking Module for approximately 8-1/2 months. This report describes the OPM experiment, a brief background of its development, program organization, experiment description, mission overview including space environment definition, performance overview, materials data including flight and ground data, in-depth post flight analysis including ground analysis measurements and a summary discussion of the findings and results.

  3. System Report for the Optical Properties Monitor (OPM) Experiment

    NASA Technical Reports Server (NTRS)

    Hummer, L.

    2001-01-01

    This systems report describes how the Optical Properties Monitor (OPM) experiment was developed. Pertinent design parameters are discussed, along with mission information and system requirements to successfully complete the mission. Environmental testing was performed on the OPM to certify it for spaceflight. This testing included vibration, thermal vacuum, electromagnetic interference and conductance, and toxicity tests. Instrument and monitor subsystem performances, including the reflectometer, vacuum ultraviolet, total integrated scatter, atomic oxygen monitor, irradiance monitor, and molecular contamination monitor during the mission are discussed. The OPM experiment was launched aboard the Space Shuttle on mission STS-81 in January 1997 and transferred to the Mir space station. An extravehicular activity (EVA) was performed in April 1997 to attach the OPM experiment to the outside of the Mir/Shuttle Docking Module for space environment exposure. The OPM conducted in situ measurements of a number of material samples. These data may be found in the OPM Science Report. OPM was retrieved during an EVA in January 1998 and was returned to Earth on board the Space Shuttle on mission STS-89.

  4. Experience with Aero- and Fluid-Dynamic Testing for Engineering and CFD Validation

    NASA Technical Reports Server (NTRS)

    Ross, James C.

    2016-01-01

    Ever since computations have been used to simulate aerodynamics the need to ensure that the computations adequately represent real life has followed. Many experiments have been performed specifically for validation and as computational methods have improved, so have the validation experiments. Validation is also a moving target because computational methods improve requiring validation for the new aspect of flow physics that the computations aim to capture. Concurrently, new measurement techniques are being developed that can help capture more detailed flow features pressure sensitive paint (PSP) and particle image velocimetry (PIV) come to mind. This paper will present various wind-tunnel tests the author has been involved with and how they were used for validation of various kinds of CFD. A particular focus is the application of advanced measurement techniques to flow fields (and geometries) that had proven to be difficult to predict computationally. Many of these difficult flow problems arose from engineering and development problems that needed to be solved for a particular vehicle or research program. In some cases the experiments required to solve the engineering problems were refined to provide valuable CFD validation data in addition to the primary engineering data. All of these experiments have provided physical insight and validation data for a wide range of aerodynamic and acoustic phenomena for vehicles ranging from tractor-trailers to crewed spacecraft.

  5. Moral responsibility, technology, and experiences of the tragic: from Kierkegaard to offshore engineering.

    PubMed

    Coeckelbergh, Mark

    2012-03-01

    The standard response to engineering disasters like the Deepwater Horizon case is to ascribe full moral responsibility to individuals and to collectives treated as individuals. However, this approach is inappropriate since concrete action and experience in engineering contexts seldom meets the criteria of our traditional moral theories. Technological action is often distributed rather than individual or collective, we lack full control of the technology and its consequences, and we lack knowledge and are uncertain about these consequences. In this paper, I analyse these problems by employing Kierkegaardian notions of tragedy and moral responsibility in order to account for experiences of the tragic in technological action. I argue that ascription of responsibility in engineering contexts should be sensitive to personal experiences of lack of control, uncertainty, role conflicts, social dependence, and tragic choice. I conclude that this does not justify evading individual and corporate responsibility, but inspires practices of responsibility ascription that are less 'harsh' on those directly involved in technological action, that listen to their personal experiences, and that encourage them to gain more knowledge about what they are doing.

  6. Coping with Variability in Model-Based Systems Engineering: An Experience in Green Energy

    NASA Astrophysics Data System (ADS)

    Trujillo, Salvador; Garate, Jose Miguel; Lopez-Herrejon, Roberto Erick; Mendialdua, Xabier; Rosado, Albert; Egyed, Alexander; Krueger, Charles W.; de Sosa, Josune

    Model-Based Systems Engineering (MBSE) is an emerging engineering discipline whose driving motivation is to provide support throughout the entire system life cycle. MBSE not only addresses the engineering of software systems but also their interplay with physical systems. Quite frequently, successful systems need to be customized to cater for the concrete and specific needs of customers, end-users, and other stakeholders. To effectively meet this demand, it is vital to have in place mechanisms to cope with the variability, the capacity to change, that such customization requires. In this paper we describe our experience in modeling variability using SysML, a leading MBSE language, for developing a product line of wind turbine systems used for the generation of electricity.

  7. Band gap engineering and optical properties of tungsten trioxide

    NASA Astrophysics Data System (ADS)

    Ping, Yuan; Li, Yan; Rocca, Dario; Gygi, Francois; Galli, Giulia

    2012-02-01

    Tungsten trioxide (WO3) is a good photoanode material for water oxidation but it is not an efficient absorber of sunlight because of its large band gap (2.6 eV). Recently, stable clathrates of WO3 with interstitial N2 molecules were synthesized [1], which are isostructural to monoclinic WO3 but have a substantially smaller bang gap, 1.8 eV. We have studied the structural, electronic, an vibrational properties of N2-WO3 clathrates using ab-initio calculations and analyzed the physical origin of their gap reduction. We also studied the effect of atomic dopants, in particular rare gases. Substantial band gap reduction has been observed, especially in the case of doping with Xe, due to both electronic and structural effects. Absorption spectra have been computed by solving the Bethe-Salpeter Equation [2] to gain a thourough insight into the optical properties of pure and doped tungsten trioxide. [1] Q. Mi, Y. Ping, Y. Li., B.S. Brunschwig, G. Galli, H B. Gray, N S. Lewis (preprint) [2]D. Rocca, D. Lu and G. Galli, J. Chem. Phys. 133, 164109 (2010)

  8. Optical properties of biomimetic probes engineered from erythrocytes

    NASA Astrophysics Data System (ADS)

    Burns, Joshua M.; Saager, Rolf; Majaron, Boris; Jia, Wangcun; Anvari, Bahman

    2017-01-01

    Light-activated theranostic materials offer a potential platform for optical imaging and phototherapeutic applications. We have engineered constructs derived from erythrocytes, which can be doped with the FDA-approved near infrared (NIR) chromophore, indocyanine green (ICG). We refer to these constructs as NIR erythrocyte-mimicking transducers (NETs). Herein, we investigated the effects of changing the NETs mean diameter from micron- (≈4 μm) to nano- (≈90 nm) scale, and the ICG concentration utilized in the fabrication of NETs from 5 to 20 μM on the resulting absorption and scattering characteristics of the NETs. Our approach consisted of integrating sphere-based measurements of light transmittance and reflectance, and subsequent utilization of these measurements in an inverse adding-doubling algorithm to estimate the absorption (μ a) and reduced scattering (μ s‧) coefficients of these NETs. For a given NETs diameter, values of μ a increased over the approximate spectral band of 630-860 nm with increasing ICG concentration. Micron-sized NETs produced the highest peak value of μ a when using ICG concentrations of 10 and 20 μM, and showed increased values of μ s‧ as compared to nano-sized NETs. Spectral profiles of μ s‧ for these NETs showed a trend consistent with Mie scattering behavior for spherical objects. For all NETs investigated, changing the ICG concentration minimally affected the scattering characteristics. A Monte Carlo-based model of light distribution showed that the presence of these NETs enhanced the fluence levels within simulated blood vessels. These results provide important data towards determining the appropriate light dosimetry parameters for an intended light-based biomedical application of NETs.

  9. Engineering aspects of the experiment and results of animal tests. [Apollo 17 Biological Cosmic Ray Experiment

    NASA Technical Reports Server (NTRS)

    Look, B. C.; Tremor, J. W.; Barrows, W. F.; Zabower, H. R.; Suri, K.; Park, E. G., Jr.; Durso, J. A.; Leon, H. A.; Haymaker, W.; Lindberg, R. G.

    1975-01-01

    A closed passive system independent of support from the spacecraft or its crew was developed to house five pocket mice for their flight on Apollo XVII. The reaction of potassium superoxide with carbon dioxide and water vapor to produce oxygen provided a habitable atmosphere within the experiment package. The performance of the system and the ability of the mice to survive the key preflight tests gave reasonable assurance that the mice would also withstand the Apollo flight.-

  10. Chitosan fibers with improved biological and mechanical properties for tissue engineering applications.

    PubMed

    Albanna, Mohammad Z; Bou-Akl, Therese H; Blowytsky, Oksana; Walters, Henry L; Matthew, Howard W T

    2013-04-01

    The low mechanical properties of hydrogel materials such as chitosan hinder their broad utility for tissue engineering applications. Previous research efforts improved the mechanical properties of chitosan fiber through chemical and physical modifications; however, unfavorable toxicity effects on cells were reported. In this paper, we report the preparation of chitosan fibers with improved mechanical and biocompatibility properties. The structure-property relationships of extruded chitosan fibers were explored by varying acetic acid (AA) concentration, ammonia concentration, annealing temperature and degree of heparin crosslinking. Results showed that optimizing AA concentration to 2vol% improved fiber strength and stiffness by 2-fold. Extruding chitosan solution into 25wt% of ammonia solution reduced fiber diameters and improved fiber strength by 2-fold and stiffness by 3-fold, due to an increase in crystallinity as confirmed by XRD. Fiber annealing further reduced fiber diameter and improved fiber strength and stiffness as temperature increased. Chitosan fibers crosslinked with heparin had increased diameter but lower strength and stiffness properties and higher breaking strain values. When individual parameters were combined, further improvement in fiber mechanical properties was achieved. All mechanically improved fibers and heparin crosslinked fibers promoted valvular interstitial cells (VIC) attachment and growth over 10 day cultures. Our results demonstrate the ability to substantially improve the mechanical properties of chitosan fibers without adversely affecting their biological properties. The investigated treatments offer numerous advantages over previous physical/chemical modifications and thus are expected to expand the utility of chitosan fibers with tunable mechanical properties in various tissue engineering applications.

  11. Real gas properties and Space Shuttle Main Engine fuel turbine performance prediction

    NASA Technical Reports Server (NTRS)

    Harloff, G. J.

    1987-01-01

    The H2/H2O mixture thermodynamic and transport properties variations for the Space Shuttle Main Engine (SSME) fuel turbine over a range of temperatures and pressures are examined. The variation of molecular viscosity, specific heat at constant pressure, and Prandtl number for the hydrogen/steam mixture are fitted using polynominal relationships for future turbine performance use. The mixture property variations are calculated using GASP and WASP computer programs. The air equivalent performance of the SSME fuel turbine is computed.

  12. ThermoData Engine (TDE): software implementation of the dynamic data evaluation concept. 5. Experiment planning and product design.

    PubMed

    Diky, Vladimir; Chirico, Robert D; Kazakov, Andrei F; Muzny, Chris D; Magee, Joseph W; Abdulagatov, Ilmutdin; Kang, Jeong Won; Kroenlein, Kenneth; Frenkel, Michael

    2011-01-24

    ThermoData Engine (TDE) is the first full-scale software implementation of the dynamic data evaluation concept, as reported recently in this journal. In the present paper, we describe development of an algorithmic approach to assist experiment planning through assessment of the existing body of knowledge, including availability of experimental thermophysical property data, variable ranges studied, associated uncertainties, state of prediction methods, and parameters for deployment of prediction methods and how these parameters can be obtained using targeted measurements, etc., and, indeed, how the intended measurement may address the underlying scientific or engineering problem under consideration. A second new feature described here is the application of the software capabilities for aid in the design of chemical products through identification of chemical systems possessing desired values of thermophysical properties within defined ranges of tolerance. The algorithms and their software implementation to achieve this are described. Finally, implementation of a new data validation and weighting system is described for vapor-liquid equilibrium (VLE) data, and directions for future enhancements are outlined.

  13. Interface engineered multifunctional oxide thin films with optimized properties

    NASA Astrophysics Data System (ADS)

    Collins, Gregory Roy

    2010-06-01

    In our world today, energy has become one of the most valuable resources, in particular, renewable and clean energy sources. The research presented here represents an investigation into three separate areas of this topic. In thin film applications, the ordered structures as well as the inherent thinness of the films precludes the normal physics found in bulk materials. Characterizations of films of this type can provide information on molecular level charge transfer processes of the film layer materials since diffusive properties are minimal. With the control given by pulsed laser deposition methods, film and interface structure can be altered allowing for an examination of these effects on the materials properties. For the electrolyte and cathode materials, this equates to finding thermal and PO2 dependencies for electronic and ionic transport. For barium titanate, aside from the effects of oxygen vacancies, the interface quality between the electrodes and the ferroelectric material determines the effectiveness of energy transfer between these boundaries. That is, poor bonding characteristics or the formation of intermediate layers will introduce inconsistencies and (possibly) unwanted piezoelectric response properties of the material which could introduce parasitic dampening (resistance) of the mechanical vibrations of a piezoelectric transducer, altering its resonant characteristics. The clean reaction products and potential for high power outputs provide a strong impetus into investigations of fuel cell structures to improve their functionality. With conventional applications being dominated by high temperature (>700 °C) cells utilizing YSZ as an electrolyte medium, much gain can be made in efficiency through the lowering of cell operation temperature. The first part of my research focuses on the growth and characterization of a novel multilayered electrolyte structure consisting of alternating layers of GCO and YSZ for use in a medium temperature (400--600

  14. Crack-Detection Experiments on Simulated Turbine Engine Disks in NASA Glenn Research Center's Rotordynamics Laboratory

    NASA Technical Reports Server (NTRS)

    Woike, Mark R.; Abdul-Aziz, Ali

    2010-01-01

    The development of new health-monitoring techniques requires the use of theoretical and experimental tools to allow new concepts to be demonstrated and validated prior to use on more complicated and expensive engine hardware. In order to meet this need, significant upgrades were made to NASA Glenn Research Center s Rotordynamics Laboratory and a series of tests were conducted on simulated turbine engine disks as a means of demonstrating potential crack-detection techniques. The Rotordynamics Laboratory consists of a high-precision spin rig that can rotate subscale engine disks at speeds up to 12,000 rpm. The crack-detection experiment involved introducing a notch on a subscale engine disk and measuring its vibration response using externally mounted blade-tip-clearance sensors as the disk was operated at speeds up to 12 000 rpm. Testing was accomplished on both a clean baseline disk and a disk with an artificial crack: a 50.8-mm- (2-in.-) long introduced notch. The disk s vibration responses were compared and evaluated against theoretical models to investigate how successful the technique was in detecting cracks. This paper presents the capabilities of the Rotordynamics Laboratory, the baseline theory and experimental setup for the crack-detection experiments, and the associated results from the latest test campaign.

  15. Freshman year computer engineering students' experiences for flipped physics lab class: An action research

    NASA Astrophysics Data System (ADS)

    Akı, Fatma Nur; Gürel, Zeynep

    2017-02-01

    The purpose of this research is to determine the university students' learning experiences about flipped-physics laboratory class. The research has been completed during the fall semester of 2015 at Computer Engineering Department of Istanbul Commerce University. In this research, also known as a teacher qualitative research design, action research method is preferred to use. The participants are ten people, including seven freshman and three junior year students of Computer Engineering Department. The research data was collected at the end of the semester with the focus group interview which includes structured and open-ended questions. And data was evaluated with categorical content analysis. According to the results, students have some similar and different learning experiences to flipped education method for physics laboratory class.

  16. Hydrodynamic parameters modulate biochemical, histological, and mechanical properties of engineered cartilage.

    PubMed

    Bueno, Ericka M; Bilgen, Bahar; Barabino, Gilda A

    2009-04-01

    Functional engineered cartilage constructs represent a promising therapeutic approach for the replacement of damaged articular cartilage. The in vitro generation of cartilage tissue suitable for repair requires an understanding of the complex interrelationships between environmental cues, such as hydrodynamic forces, and tissue growth and development. In the present study, engineered cartilage constructs were cultivated in four well-defined hydrodynamic environments within a bioreactor, and correlations were established between construct ultrastructural and mechanical properties and key hydrodynamic parameters. Results suggest that even for similar composition, constructs may exhibit different mechanical properties due to differences in their ultrastructure that can be modulated by hydrodynamic parameters. For example, improved mechanical properties were observed in constructs that exhibited a thick fibrous outer capsule as a result of cultivation under increased hydrodynamic shear. In particular, uniformity in the contribution of the fluid velocity vectors (axial, radial, and tangential) to the total fluid velocity and shear stress were the hydrodynamic parameters that most affected the construct properties under investigation. The correlations identified here may be useful in the development of engineered tissue growth models that inform the design of bioreactor cultivation systems toward the production of clinically relevant engineered cartilage.

  17. Fuel Property Effects on the Cold Startability of Navy High-Speed Diesel Engines.

    DTIC Science & Technology

    1985-12-01

    207 MAY 1 81%7I By A.F. Montemayor D W E.C. Owens J. P. Buckingham Belvoir Fuels and Lubricants Research Facility (SwRI) Southwest Research Institute...Property Effects on the Cold Startability of Navy High-Speed Diesel Engines (U) 12. PERSONAL AUTHORIS) Montemayor , A.F.; Owens, E.C.; Buckingham, J.P.; Jung

  18. Properties of Zeolite A Obtained from Powdered Laundry Detergent: An Undergraduate Experiment.

    ERIC Educational Resources Information Center

    Smoot, Alison L.; Lindquist, David A.

    1997-01-01

    Presents experiments that introduce students to the myriad properties of zeolites using the sodium form of zeolite A (Na-A) from laundry detergent. Experiments include extracting Na-A from detergent, water softening properties, desiccant properties, ion-exchange properties, and Zeolite HA as a dehydration catalyst. (JRH)

  19. Improving magnetic properties of MgB2 bulk superconductors by synthetic engine oil treatment

    NASA Astrophysics Data System (ADS)

    Taylan Koparan, E.; Savaskan, B.; Yanmaz, E.

    2016-08-01

    The present study focuses on the effects of standby time of the MgB2 samples immersed in synthetic engine oil on the critical current density (Jc(H)), magnetic field dependence of the pinning force density fp(b) and Tc performances of MgB2 bulk superconductors. Synthetic engine oil was used as a product which is cheap and a rich carbon source. Manufactured MgB2 pellet samples were immersed at different standby time of 30 min, 120 min, 300 min and 1440 min in synthetic engine oil after the first heating process. Finally, MgB2 samples immersed in synthetic engine oil were sintered at 1000 °C and kept for 15 min in Ar atmosphere. The critical current density of all of MgB2 samples immersed at different standby time in engine oil in whole field range was better than that of the pure MgB2 sample because of the number of the pinning centers. The MgB2 sample immersed at 300 min standby time in synthetic engine oil has the best performance compared to other samples. The Jc value for the pure sample is 2.0 × 103 A/cm2, whereas for the MgB2 sample immersed at 300 min standby time in engine oil the Jc is enhanced to 4.8 × 103A/cm2 at 5 K and 3 T. The superconducting transition temperature (Tc) did not change with the increasing standby time of the samples in synthetic engine oil at all. The best diamagnetic property was obtained from the sample which kept in synthetic engine oil for 300 min. Synthetic engine oil treatment results in remarkable improvement of the critical current density and pinning force performances of MgB2 superconductors. It was found that all MgB2 samples have a different pinning property at different measuring temperatures. Using synthetic engine oil as a product which is cheap and a rich carbon source in MgB2 bulk superconductors makes MgB2 samples immersed in synthetic engine oil a good candidate for industrial applications.

  20. Engineering the electronic properties of nanowires for device applications

    NASA Astrophysics Data System (ADS)

    Thelander, Claes

    2007-03-01

    Semiconductor nanowires have recently been recognized as a possible add-on technology to silicon CMOS. Successful integration of nanowires may push the miniaturization of components further and could also bring improved, and completely new, device functions to a chip. In particular, nanowires composed of III-V materials are of interest for applications as they benefit from a small and/or direct bandgap. We will present results from electrical measurements on InAs/InP nanowires grown by chemical beam epitaxy. Changes in the precursors fed to the growth chamber can be made to control the electronic properties of the grown material. In this way it is possible to create atomically sharp heterostructure interfaces, as well as to change the carrier concentration along the wire. The latter can be achieved by controlling the carbon incorporation from the In precursor. It will be shown that heterostructure nanowires can be used in memory cells, and also as single-electron transistors for electrostatic read-out of such cells. Finally, we will discuss the design and application of InAs nanowire-based field-effect transistors, where issues related to lateral and vertical processing of nanowires will be addressed.

  1. On-orbit truss structure tele-operation experiment by Engineering Test Satellite-7

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Isao; Matsumoto, Koutarou; Kida, Takashi

    1994-08-01

    This report describes a preliminary ground test using the laboratory model of a truss structure and small research manipulator system which is a scaled model of the on-orbit truss structure experiment on Engineering Test Satellite-7(ETS-7). ETS-7 will be launched into low earth orbit by the H-2 rocket in 1997. This experimental application satellite is now being developed to establish rendezvous and docking technologies and remote tele-robotics technologies. National Aerospace Laboratory will participate in on-orbit experiments of remote deployment and construction of truss structures by using an on-board manipulator system.

  2. Online monitoring of mechanical properties of three-dimensional tissue engineered constructs for quality assessment

    NASA Astrophysics Data System (ADS)

    Reinwald, Yvonne; Bagnaninchi, Pierre O.; Yang, Ying; Baba Ismail, Yanny M.; El Haj, Alicia J.

    2016-03-01

    Mechanical preconditioning and mechanical properties of tissue engineered constructs are essential for their capability to regenerate damaged tissues. To online monitor the mechanical properties a hydrostatic pressure bioreactor was coupled with optical coherence tomography into a new image modality termed hydrostatic pressure optical coherence elastography (HP-OCE). HP-OCE was utilised to assess the properties of three-dimensional (3D) tissue constructs while being physically stimulated within the hydrostatic force bioreactor. Hydrogels have been infiltrated into porous rapid prototyped or salt-leached scaffolds to mimic heterogeneous mechanical properties of cell-seeded constructs. Variations of mechanical properties in the solid scaffolds and agarose gels with different gel concentrations as well as the presences of cells have been clearly delineated by HP-OCE. Results indicate that HP-OCE allows contactless real-time non-invasive monitoring of the mechanical properties of tissue constructs and the effect of physical stimulation on cellular activities.

  3. Structural, magnetic, and transport properties of Permalloy for spintronic experiments

    SciTech Connect

    Nahrwold, Gesche; Scholtyssek, Jan M.; Motl-Ziegler, Sandra; Albrecht, Ole; Merkt, Ulrich; Meier, Guido

    2010-07-15

    Permalloy (Ni{sub 80}Fe{sub 20}) is broadly used to prepare magnetic nanostructures for high-frequency experiments where the magnetization is either excited by electrical currents or magnetic fields. Detailed knowledge of the material properties is mandatory for thorough understanding its magnetization dynamics. In this work, thin Permalloy films are grown by dc-magnetron sputtering on heated substrates and by thermal evaporation with subsequent annealing. The specific resistance is determined by van der Pauw methods. Point-contact Andreev reflection is employed to determine the spin polarization of the films. The topography is imaged by atomic-force microscopy, and the magnetic microstructure by magnetic-force microscopy. Transmission-electron microscopy and transmission-electron diffraction are performed to determine atomic composition, crystal structure, and morphology. From ferromagnetic resonance absorption spectra the saturation magnetization, the anisotropy, and the Gilbert damping parameter are determined. Coercive fields and anisotropy are measured by magneto-optical Kerr magnetometry. The sum of the findings enables optimization of Permalloy for spintronic experiments.

  4. Experience with integrally-cast compressor and turbine components for a small, low-cost, expendable-type turbojet engine

    NASA Technical Reports Server (NTRS)

    Dengler, R. P.

    1975-01-01

    A discussion regarding experiences with integrally-cast compressor and turbine components during fabrication and testing of four engine assemblies of a small (29 cm (11-1/2 in.) maximum diameter) experimental turbojet engine design for an expendable application is presented. Various operations such as metal removal, welding, and re-shaping of these components are performed in preparation of full-scale engine tests. Engines with these components have been operated for a total of 157 hours at engine speeds as high as 38,000 rpm and at turbine inlet temperatures as high as 1256 K (1800 F).

  5. Experience with integrally-cast compressor and turbine components for a small, low-cost, expendable-type turbojet engine

    NASA Technical Reports Server (NTRS)

    Dengler, R. P.

    1975-01-01

    Experiences with integrally-cast compressor and turbine components during fabrication and testing of four engine assemblies of a small (29 cm (11 1/2 in.) maximum diameter) experimental turbojet engine design for an expendable application are discussed. Various operations such as metal removal, welding, and re-shaping of these components were performed in preparation of full-scale engine tests. Engines with these components were operated for a total of 157 hours at engine speeds as high as 38,000 rpm and at turbine inlet temperatures as high as 1256 K (1800 F).

  6. Dielectric Property Enhancement in Polymer Composites with Engineered Interfaces

    NASA Astrophysics Data System (ADS)

    Krentz, Timothy Michael

    This thesis reports studies into the dielectric behavior of polymer composites filled with silica nanoparticles. The permittivity and dielectric breakdown strength (DBS) of these materials are critical to their performance in insulating applications such as high voltage power transmission. Until now, the mechanisms which lead to improvements in DBS in these systems have been poorly understood, in part because the effects of dispersion of the filler and the filler's surface electronic characteristics have been confused. The new surface modifications created in this thesis permit these two parameters to be addressed independently, leading to the hypothesis that nanocomposite dielectric materials exhibit DBS enhancement when electron avalanches are prevented from proceeding to reach a critical size capable of causing failure. The same control of dispersion and surface properties also lead to changes in the permittivity of the composite based upon the polarizability and trapping behavior of the filler. In this work, the dispersion and surface states of silica nanoparticles were independently controlled with two separate populations of surface molecules. Two matrix materials were studied, and in each system, a different, matrix-compatible long chain polymer is required to control dispersion. Conversely, a second population of short molecules is shown to be capable of creating electronic traps associated with the silica nanoparticle surface which lead to DBS enhancements largely independent of the matrix, indicating that the same failure mechanism is operating in both epoxy and polypropylene. Progressive variation in dispersion quality is attained with this surface modification scheme. This creates progressively smaller volumes of matrix polymer unaffected by the filler. This work shows that when these volumes approach and become smaller than the same scale as predicted for electron avalanches, the greatest changes in DBS are seen. Likewise, the plateau behavior of this

  7. Engineered Surface Properties of Porous Tungsten from Cryogenic Machining

    NASA Astrophysics Data System (ADS)

    Schoop, Julius Malte

    Porous tungsten is used to manufacture dispenser cathodes due to it refractory properties. Surface porosity is critical to functional performance of dispenser cathodes because it allows for an impregnated ceramic compound to migrate to the emitting surface, lowering its work function. Likewise, surface roughness is important because it is necessary to ensure uniform wetting of the molten impregnate during high temperature service. Current industry practice to achieve surface roughness and surface porosity requirements involves the use of a plastic infiltrant during machining. After machining, the infiltrant is baked and the cathode pellet is impregnated. In this context, cryogenic machining is investigated as a substitutionary process for the current plastic infiltration process. Along with significant reductions in cycle time and resource use, surface quality of cryogenically machined un-infiltrated (as-sintered) porous tungsten has been shown to significantly outperform dry machining. The present study is focused on examining the relationship between machining parameters and cooling condition on the as-machined surface integrity of porous tungsten. The effects of cryogenic pre-cooling, rake angle, cutting speed, depth of cut and feed are all taken into consideration with respect to machining-induced surface morphology. Cermet and Polycrystalline diamond (PCD) cutting tools are used to develop high performance cryogenic machining of porous tungsten. Dry and pre-heated machining were investigated as a means to allow for ductile mode machining, yet severe tool-wear and undesirable smearing limited the feasibility of these approaches. By using modified PCD cutting tools, high speed machining of porous tungsten at cutting speeds up to 400 m/min is achieved for the first time. Beyond a critical speed, brittle fracture and built-up edge are eliminated as the result of a brittle to ductile transition. A model of critical chip thickness ( hc ) effects based on cutting

  8. Biomechanical properties of the spinal cord: implications for tissue engineering and clinical translation.

    PubMed

    Bartlett, Richard D; Choi, David; Phillips, James B

    2016-10-01

    Spinal cord injury is a severely debilitating condition which can leave individuals paralyzed and suffering from autonomic dysfunction. Regenerative medicine may offer a promising solution to this problem. Previous research has focused primarily on exploring the cellular and biological aspects of the spinal cord, yet relatively little remains known about the biomechanical properties of spinal cord tissue. Given that a number of regenerative strategies aim to deliver cells and materials in the form of tissue-engineered therapies, understanding the biomechanical properties of host spinal cord tissue is important. We review the relevant biomechanical properties of spinal cord tissue and provide the baseline knowledge required to apply these important physical concepts to spinal cord tissue engineering.

  9. Strain properties analysis and wireless collection system of PVDF for structural local health monitoring of civil engineering structures

    NASA Astrophysics Data System (ADS)

    Yu, Yan; Wang, Yang; Dong, Weijie; Jin, Yajing; Ou, Jinping

    2009-07-01

    For large civil engineering structures and base establishments, for example, bridges, super-high buildings, long-span space structures, offshore platforms and pipe systems of water & gas supply, their lives are up to a few decades or centuries. Damaged by environmental loads, fatigue effects, corrosion effects and material aging, these structures experience inevitably such side effects as damage accumulation, resistance reduction and even accidents. The traditional civil structure is a kind of passive one, whose performance and status are unpredictable to a great extent, but the informatics' introduction breaks a new path to obtain the status of the structure, thus it is an important research direction to evaluate and improve reliability of civil structures by the use of monitoring and health diagnosis technique, and this also assures the security of service for civil engineering structures. Smart material structure, originated from the aerospace sector, has been a research hotspot in civil engineering, medicine, shipping, and so on. For structural health monitoring of civil engineering, the research about high-performance sensing unit of smart material structure is very important, and this will possibly push further the development and application of monitoring and health diagnosis techniques. At present, piezoelectric materials are one of the most widely used sensing materials among the research of smart material structures. As one of the piezoelectric materials, PVDF(Polyvinylidene Fluoride)film is widely considered for the advantages of low cost, good mechanical ability, high sensibility, the ability of being easily placed and resistance of corrosion. However, only a few studies exit about building a mature monitoring system using PVDF. In this paper, for the sake of using PVDF for sensing unit for structural local monitoring of civil engineering, the strain sensing properties of PVDF are studied in detail. Firstly, the operating mechanism of PVDF is analyzed

  10. Physicochemical and optical properties of combustion-generated particles from Ship Diesel Engines

    NASA Astrophysics Data System (ADS)

    Kim, H.; Jeong, S.; Jin, H. C.; Kim, J. Y.

    2015-12-01

    Shipping contributes significantly to the anthropogenic burden of particulate matter (PM), and is among the world's highest polluting combustion sources per fuel consumed. Moreover, ships are a highly concentrated source of pollutants which are emitted into clean marine environments (e.g., Artic region). Shipping utilizes heavy fuel oil (HFO) which is less distilled compared to fuels used on land and few investigations on shipping related PM properties are available. BC is one of the dominant combustion products of ship diesel engines and its chemical and microphysical properties have a significant impact on climate by influencing the amount of albedo reduction on bright surfaces such as in polar regions. We have carried out a campaign to characterize the PM emissions from medium-sized marine engines in Gunsan, Jeonbuk Institute of Automotive Technology. The properties of ship-diesel PM have characterized depending on (1) fuel sulfur content (HFO vs. ULSD) and (2) engine conditions (Running state vs. Idling state). Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX) equipped with HRTEM and Raman spectroscopy were used for physicochemical analysis. Optical properties, which are ultimately linked to the snow/ice albedo decrease impacting climate, were assessed as well. PM generated under high engine temperature conditions had typical features of soot, e.g., concentric circles comprised of closely packed graphene layers, however PM generated by the idling state at low combustion temperature was characterized by amorphous and droplet-like carbonaceous particles with no crystalline structure. Significant differences in optical properties depending on the combustion conditions were also observed. Particles from running conditions showed wavelength-independent absorbing properties, whereas the particles from idling conditions showed enhanced absorption at shorter wavelengths, which is

  11. High School Graphics Experience Influencing the Self-Efficacy of First-Year Engineering Students in an Introductory Engineering Graphics Course

    ERIC Educational Resources Information Center

    Metraglia, Riccardo; Villa, Valerio; Baronio, Gabriele; Adamini, Riccardo

    2015-01-01

    Today's students enter engineering colleges with different technical backgrounds and prior graphics experience. This may due to their high school of provenience, which can be technical or non-technical. The prior experience affects students' ability in learning and hence their motivation and self-efficacy beliefs. This study intended to evaluate…

  12. Characteristic of blended fuel properties and engine cycle-to-cycle variations with butanol additive

    NASA Astrophysics Data System (ADS)

    Ali, Obed M.; Mamat, Rizalman; Abdullah, Nik R.; Abdullah, Abdul Adam

    2015-05-01

    Biodiesel fuel characteristics are one of the most important parameters that limited their application in diesel engines. Though biodiesel-diesel blended fuel can replace diesel satisfactorily at low blending ratios up to 20%, problems related to fuel property persist at high blending ratio. Hence, in the present study, the feasibility of biodiesel-diesel blended fuel B30 was investigated with respect to its properties and engine cyclic variations with increasing butanol additive. The blended fuel with additive were tested experimentally in a diesel engine and the in-cylinder pressure data were collected and analyzed using the coefficient of variation and wavelet power spectrum to evaluate the engine cyclic variations compared to diesel fuel engine test results. The fuel property test results showed slight improvement in density and acid value with significant reduction in viscosity when increasing butanol additive. Furthermore, the blended fuel pour point was reduced to -6 °C at 8% butanol additive. On the other hand, the energy content slightly affected with increasing butanol additive in the blend. From the wavelet power spectrum, it is observed that the short-period oscillations appear intermittently in pure blended fuel, while the long and intermediate-term periodicities tends to appear with increasing additive ratio. Moreover, the spectral power increased with an increase in the additive ratio indicating that the additive has a noticeable effect on increasing the cycle to cycle variation. The coefficient of variation of indicated mean effective pressure for B30 were found to be the lowest and increases with increasing additive ratios. Both the wavelet analysis and coefficient of variation results reveals that blended fuel B30 has engine cyclic variations comparable to diesel fuel with increasing butanol additive up to 4%.

  13. Gelatin Scaffolds with Controlled Pore Structure and Mechanical Property for Cartilage Tissue Engineering.

    PubMed

    Chen, Shangwu; Zhang, Qin; Nakamoto, Tomoko; Kawazoe, Naoki; Chen, Guoping

    2016-03-01

    Engineering of cartilage tissue in vitro using porous scaffolds and chondrocytes provides a promising approach for cartilage repair. However, nonuniform cell distribution and heterogeneous tissue formation together with weak mechanical property of in vitro engineered cartilage limit their clinical application. In this study, gelatin porous scaffolds with homogeneous and open pores were prepared using ice particulates and freeze-drying. The scaffolds were used to culture bovine articular chondrocytes to engineer cartilage tissue in vitro. The pore structure and mechanical property of gelatin scaffolds could be well controlled by using different ratios of ice particulates to gelatin solution and different concentrations of gelatin. Gelatin scaffolds prepared from ≥70% ice particulates enabled homogeneous seeding of bovine articular chondrocytes throughout the scaffolds and formation of homogeneous cartilage extracellular matrix. While soft scaffolds underwent cellular contraction, stiff scaffolds resisted cellular contraction and had significantly higher cell proliferation and synthesis of sulfated glycosaminoglycan. Compared with the gelatin scaffolds prepared without ice particulates, the gelatin scaffolds prepared with ice particulates facilitated formation of homogeneous cartilage tissue with significantly higher compressive modulus. The gelatin scaffolds with highly open pore structure and good mechanical property can be used to improve in vitro tissue-engineered cartilage.

  14. Measurement of Sedimentary Interbed Hydraulic Properties and Their Hydrologic Influence near the Idaho Nuclear Technology and Engineering Center at the Idaho National Engineering and Environmental Laboratory

    USGS Publications Warehouse

    Perkins, Kim S.

    2003-01-01

    Disposal of wastewater to unlined infiltration ponds near the Idaho Nuclear Technology and Engineering Center (INTEC), formerly known as the Idaho Chemical Processing Plant, at the Idaho National Engineering and Environmental Laboratory (INEEL) has resulted in the formation of perched water bodies in the unsaturated zone (Cecil and others, 1991). The unsaturated zone at INEEL comprises numerous basalt flows interbedded with thinner layers of coarse- to fine-grained sediments and perched ground-water zones exist at various depths associated with massive basalts, basalt-flow contacts, sedimentary interbeds, and sediment-basalt contacts. Perched ground water is believed to result from large infiltration events such as seasonal flow in the Big Lost River and wastewater discharge to infiltration ponds. Evidence from a large-scale tracer experiment conducted in 1999 near the Radioactive Waste Management Complex (RWMC), approximately 13 km from the INTEC, indicates that rapid lateral flow of perched water in the unsaturated zone may be an important factor in contaminant transport at the INEEL (Nimmo and others, 2002b). Because sedimentary interbeds, and possibly baked-zone alterations at sediment-basalt contacts (Cecil and other, 1991) play an important role in the generation of perched water it is important to assess the hydraulic properties of these units.

  15. Surface electrical properties experiment, part 1. [for measuring lunar surface electrical properties

    NASA Technical Reports Server (NTRS)

    Kupfer, W. S. (Compiler)

    1973-01-01

    The design evolution, hardware development, and production history of the surface electrical properties (SEP) experiment are discussed. The SEP transmitter and receiver were designed to be used on the lunar surface during the Apollo 17 mission. The equipment was used to measure lunar surface electrical properties over traverses totalling more than 8 kilometers, for a duration of more than 100 minutes. A comprehensive outline of the techniques, is given along with a simplified detailed breakdown of equipment description and function to outline the principles of operation. A history of the design evolution with trade-off criteria and emphasis on changes caused by decisions reached in solving problems inherent in a fast-paced development program are presented from the viewpoint of overall design concept and in detail for each item of deliverable hardware. There is a brief account of lunar operations.

  16. Interdisciplinary Undergraduate Research Experiences in Geosciences for Physical Science and Engineering Students

    NASA Astrophysics Data System (ADS)

    Bililign, S.; Schimmel, K.; Lin, Y. L.; Germuth, A.

    2014-12-01

    The recruitment of undergraduate students, especially minorities, into geoscience career paths continues to be a challenge. One approach for addressing this issue involves providing geoscience research experiences. Therefore, the outcomes of an undergraduate research program (REU) focused on recruiting science (physics, mathematics, chemistry) and engineering (electrical) students for an interdisciplinary research experience in geosciences will be presented. The program design has several unique features that include: (1) projects with clear societal implications, (2) projects involve multiple faculty members (at least two) and expose students to interdisciplinary approaches and thinking, (3) partnerships between national labs and universities to provide cutting-edge research, educational, and professional development opportunities for students, (4) student engagement in the creation of personalized professional development plans, (5) combined summer and academic year research experiences. Pre- and post-assessment results, successes, and challenges will be presented.

  17. Sodium Handling Technology and Engineering Design of the Madison Dynamo Experiment.

    NASA Astrophysics Data System (ADS)

    Kendrick, R.; Forest, C. B.; O'Connell, R.; Wright, A.; Robinson, K.

    1998-11-01

    A new liquid metal MHD experiment is being constructed at the University of Wisconsin to test several key predictions of dynamo theory: magnetic instabilities driven by sheared flow, the effects of turbulence on current generation, and the back-reaction of the self-generated magnetic field on the fluid motion which brings saturation. This presentation describes the engineering design of the experiment, which is a 0.5 m radius spherical vessel, filled with liquid sodium at 150 degrees Celsius. The experiment is designed to achieve a magnetic Reynolds number in excess of 100, which requires approximately 80 Hp of mechanical drive, producing flow velocities in sodium of 15 m/s through impellers. Handling liquid sodium offers a number of technical challenges, but routine techniques have been developed over the past several decades for safely handling large quantities for the fast breeder reactor. The handling strategy is discussed, technical details concerning seals and pressurazation are presented, and safety elements are highlighted.

  18. Learning from experience: the realities of developing mathematics courses for an online engineering programme

    NASA Astrophysics Data System (ADS)

    Quinn, Diana; Albrecht, Amie; Webby, Brian; White, Kevin

    2015-10-01

    Rarely do university departments of mathematics redesign their basic mathematics courses. Through developing an online version of our associate degree in engineering in collaboration with Open Universities Australia, we redesigned the first in a sequence of five engineering mathematics courses. The online cohort proved different to our face-to-face experience. We embarked on a process of refining the unit using experiential learning and action research. The 13 week unit is delivered up to four times a year and this paper reviews the first 10 cycles of enhancements over 3 years and unpacks the layers of hypotheses underlying development decisions. Several category themes were identified with a focus on students, teachers and learning activities. Investment in online developments for mathematics can have multiple flow-on impacts for other teaching modes. Good curriculum design, regardless of environment, will always be a cornerstone of effective course development processes.

  19. Estimation of engineering properties of selected tuffs by using grain/matrix ratio

    NASA Astrophysics Data System (ADS)

    Korkanç, Mustafa; Solak, Burak

    2016-08-01

    Petrographic properties of rocks substantially affect their physical and mechanical properties. In the present study, for the purpose of examining the relationship between the petrographic and geomechanical properties of pyroclastic rocks, fresh samples were taken from tuffs of different textural properties that have wide distribution in Cappadocia region. Experimental studies were conducted on 20 fresh samples to determine their engineering properties through petrographic examinations. Dry and saturated unit weights, water absorption by weight, effective porosity, capillary water absorption, slake durability index, P-wave velocity, point load index, uniaxial compressive strength and nail penetration index of the samples were determined. Higher geomechanical values were obtained from the samples of Kavak tuffs affected by hydromechanical alteration and by tuffs with high welded rates. On thin sections prepared with the fresh samples, petrographic studies were carried out by using a point counter with a polarizing microscope, and mineral composition, texture, void ratio, volcanic glass presence and state of these fragments within the rock, secondary mineral formation and opaque mineral presence were determined. Grain/matrix ratio (GMR) was calculated by using the ratios of phenocrysts, microlites, volcanic glass, voids and opaque minerals after point counting on thin sections. A potential relationship between the petrographic and geomechanical properties of fresh samples was tried to determine by counting correlation analysis. Such a relationship can be significantly and extensively suggestible for engineering applications. For this purpose, we used the poorly-welded Kavak and densely-welded Kızılkaya tuff samples in our study.

  20. Photoresponsive Polysaccharide-Based Hydrogels with Tunable Mechanical Properties for Cartilage Tissue Engineering.

    PubMed

    Giammanco, Giuseppe E; Carrion, Bita; Coleman, Rhima M; Ostrowski, Alexis D

    2016-06-15

    Photoresponsive hydrogels were obtained by coordination of alginate-acrylamide hybrid gels (AlgAam) with ferric ions. The photochemistry of Fe(III)-alginate was used to tune the chemical composition, mechanical properties, and microstructure of the materials upon visible light irradiation. The photochemical treatment also induced changes in the swelling properties and transport mechanism in the gels due to the changes in material composition and microstructure. The AlgAam gels were biocompatible and could easily be dried and rehydrated with no change in mechanical properties. These gels showed promise as scaffolds for cartilage tissue engineering, where the photochemical treatment could be used to tune the properties of the material and ultimately change the growth and extracellular matrix production of chondrogenic cells. ATDC5 cells cultured on the hydrogels showed a greater than 2-fold increase in the production of sulfated glycosaminoglycans (sGAG) in the gels irradiated for 90 min compared to the dark controls. Our method provides a simple photochemical tool to postsynthetically control and adjust the chemical and mechanical environment in these gels, as well as the pore microstructure and transport properties. By changing these properties, we could easily access different levels of performance of these materials as substrates for tissue engineering.

  1. Liquid Water Cloud Properties During the Polarimeter Definition Experiment (PODEX)

    NASA Technical Reports Server (NTRS)

    Alexandrov, Mikhail D.; Cairns, Brian; Wasilewski, Andrzei P.; Ackerman, Andrew S.; McGill, Matthew J.; Yorks, John E.; Hlavka, Dennis L.; Platnick, Steven; Arnold, George; Van Diedenhoven, Bastiaan; Chowdhary, Jacek; Ottaviani, Matteo; Knobelspiesse, Kirk D.

    2015-01-01

    We present retrievals of water cloud properties from the measurements made by the Research Scanning Polarimeter (RSP) during the Polarimeter Definition Experiment (PODEX) held between January 14 and February 6, 2013. The RSP was onboard the high-altitude NASA ER-2 aircraft based at NASA Dryden Aircraft Operation Facility in Palmdale, California. The retrieved cloud characteristics include cloud optical thickness, effective radius and variance of cloud droplet size distribution derived using a parameter-fitting technique, as well as the complete droplet size distribution function obtained by means of Rainbow Fourier Transform. Multi-modal size distributions are decomposed into several modes and the respective effective radii and variances are computed. The methodology used to produce the retrieval dataset is illustrated on the examples of a marine stratocumulus deck off California coast and stratus/fog over California's Central Valley. In the latter case the observed bimodal droplet size distributions were attributed to two-layer cloud structure. All retrieval data are available online from NASA GISS website.

  2. Novel xylan-binding properties of an engineered family 4 carbohydrate-binding module.

    PubMed

    Cicortas Gunnarsson, Lavinia; Montanier, Cedric; Tunnicliffe, Richard B; Williamson, Mike P; Gilbert, Harry J; Nordberg Karlsson, Eva; Ohlin, Mats

    2007-09-01

    Molecular engineering of ligand-binding proteins is commonly used for identification of variants that display novel specificities. Using this approach to introduce novel specificities into CBMs (carbohydrate-binding modules) has not been extensively explored. Here, we report the engineering of a CBM, CBM4-2 from the Rhodothermus marinus xylanase Xyn10A, and the identification of the X-2 variant. As compared with the wild-type protein, this engineered module displays higher specificity for the polysaccharide xylan, and a lower preference for binding xylo-oligomers rather than binding the natural decorated polysaccharide. The mode of binding of X-2 differs from other xylan-specific CBMs in that it only has one aromatic residue in the binding site that can make hydrophobic interactions with the sugar rings of the ligand. The evolution of CBM4-2 has thus generated a xylan-binding module with different binding properties to those displayed by CBMs available in Nature.

  3. Characterizing Design Cognition of High School Students: Initial Analyses Comparing Those with and without Pre-Engineering Experiences

    ERIC Educational Resources Information Center

    Wells, John; Lammi, Matthew; Gero, John; Grubbs, Michael E.; Paretti, Marie; Williams, Christopher

    2016-01-01

    Reported in this article are initial results from of a longitudinal study to characterize the design cognition and cognitive design styles of high school students with and without pre-engineering course experience over a 2-year period, and to compare them with undergraduate engineering students. The research followed a verbal protocol analysis…

  4. The Relationship of Learning Communities to Engineering Students' Perceptions of the Freshman Year Experience, Academic Performance, and Persistence

    ERIC Educational Resources Information Center

    Tolley, Patricia Ann Separ

    2009-01-01

    The purpose of this correlational study was to examine the effects of a residential learning community and enrollment in an introductory engineering course to engineering students' perceptions of the freshman year experience, academic performance, and persistence. The sample included students enrolled in a large, urban, public, research university…

  5. Status of the Combined-Cycle Engine Large-Scale Inlet Mode Transition Experiment

    NASA Technical Reports Server (NTRS)

    Slater, John W.; Saunders, J. Dave

    2011-01-01

    The Large-Scale Inlet Mode Transition (LIMX) experiment is currently being conducted in the 10x10 foot supersonic wind tunnel at the NASA Glenn Research Center. The experiment has involved the efforts of a team for over four years to get to the first phase of testing, which is examining the aerodynamic characteristics of the inlet. The LIMX inlet involves dual flowpaths: one to provide flow to a turbine engine and one to provide flow to a dual-mode ramjet/scramjet. A rotating splitter cowl can close off the turbine flowpath, which would occur as the propulsion system transitions from turbine power to ramjet/scramjet power at Mach 4. The first phase of the experiment will simulate the turbine and ramjet/scramjet flows using cold pipes with flow rates controlled by mass-flow plugs. Much of the testing will characterize the performance of the turbine flowpath (total pressure recovery and distortion at the engine face location) as factors such as bleed rates and configuration and vortex generators are varied during the inlet mode transition. The performance of the inlet will also be examined at off-design Mach numbers (2.5-3.0) and at angle-of-attack.

  6. Ultrasound Imaging Techniques for Spatiotemporal Characterization of Composition, Microstructure, and Mechanical Properties in Tissue Engineering.

    PubMed

    Deng, Cheri X; Hong, Xiaowei; Stegemann, Jan P

    2016-08-01

    Ultrasound techniques are increasingly being used to quantitatively characterize both native and engineered tissues. This review provides an overview and selected examples of the main techniques used in these applications. Grayscale imaging has been used to characterize extracellular matrix deposition, and quantitative ultrasound imaging based on the integrated backscatter coefficient has been applied to estimating cell concentrations and matrix morphology in tissue engineering. Spectral analysis has been employed to characterize the concentration and spatial distribution of mineral particles in a construct, as well as to monitor mineral deposition by cells over time. Ultrasound techniques have also been used to measure the mechanical properties of native and engineered tissues. Conventional ultrasound elasticity imaging and acoustic radiation force imaging have been applied to detect regions of altered stiffness within tissues. Sonorheometry and monitoring of steady-state excitation and recovery have been used to characterize viscoelastic properties of tissue using a single transducer to both deform and image the sample. Dual-mode ultrasound elastography uses separate ultrasound transducers to produce a more potent deformation force to microscale characterization of viscoelasticity of hydrogel constructs. These ultrasound-based techniques have high potential to impact the field of tissue engineering as they are further developed and their range of applications expands.

  7. Passaged Adult Chondrocytes Can Form Engineered Cartilage with Functional Mechanical Properties: A Canine Model

    PubMed Central

    Ng, Kenneth W.; Lima, Eric G.; Bian, Liming; O'Conor, Christopher J.; Jayabalan, Prakash S.; Stoker, Aaron M.; Kuroki, Keiichi; Cook, Cristi R.; Ateshian, Gerard A.; Cook, James L.

    2010-01-01

    It was hypothesized that previously optimized serum-free culture conditions for juvenile bovine chondrocytes could be adapted to generate engineered cartilage with physiologic mechanical properties in a preclinical, adult canine model. Primary or passaged (using growth factors) adult chondrocytes from three adult dogs were encapsulated in agarose, and cultured in serum-free media with transforming growth factor-β3. After 28 days in culture, engineered cartilage formed by primary chondrocytes exhibited only small increases in glycosaminoglycan content. However, all passaged chondrocytes on day 28 elaborated a cartilage matrix with compressive properties and glycosaminoglycan content in the range of native adult canine cartilage values. A preliminary biocompatibility study utilizing chondral and osteochondral constructs showed no gross or histological signs of rejection, with all implanted constructs showing excellent integration with surrounding cartilage and subchondral bone. This study demonstrates that adult canine chondrocytes can form a mechanically functional, biocompatible engineered cartilage tissue under optimized culture conditions. The encouraging findings of this work highlight the potential for tissue engineering strategies using adult chondrocytes in the clinical treatment of cartilage defects. PMID:19845465

  8. Synthesis and Properties of Flexible Polyurethane Using Ferric Catalyst for Hypopharyngeal Tissue Engineering

    PubMed Central

    Shen, Zhisen; Wang, Jian; Lu, Dakai; Li, Qun; Zhou, Chongchang; Zhu, Yabin; Hu, Xiao

    2015-01-01

    Biodegradable polyurethane is an ideal candidate material to fabricate tissue engineered hypopharynx from its good mechanical properties and biodegradability. We thus synthesized a hydrophilic polyurethane via reactions among polyethylene glycol (PEG), e-caprolactone (e-CL) and hexamethylene diisocyanate (HDI), and thrihydroxymethyl propane (TMP). The product possessed a fast degradability due to its good wettability and good mechanical parameters with the elongations at break (137 ± 10%) and tensile strength (4.73 ± 0.46 MPa), which will make it a good matrix material for soft tissue like hypopharynx. Its biological properties were evaluated via in vitro and in vivo tests. The results showed that this hydrophilic polyurethane material can support hypopharyngeal fibroblast growth and owned good degradability and low inflammatory reaction in subcutaneous implantation. It will be proposed as the scaffold for hypopharyngeal tissue engineering research in our future study. PMID:26236737

  9. Teaching introductory game development with unreal engine: Challenges, strategies, and experiences

    NASA Astrophysics Data System (ADS)

    Head, Nicholas A.

    From the days of Pong to 100 million dollar projects such as the Grand Theft Auto franchise, video games have evolved significantly over the years. This evolution has also changed the way game development is viewed as a career. Today, video games are one of the most profitable forms of entertainment, and game development courses are appearing at universities around the world. Even with this growth, a degree from a university has yet to be an important factor in finding a job in game development (Owen, 2013). This thesis examines a method of creating and implementing an introductory gaming course and recommends ways to improve the curriculum. The main focus of the course was to introduce game development to the students. Each week, they were given an exercise that covered a different topic. Students also took part in a team project in which they were tasked with creating a complete game. The goal of the team projects was to expand the student's basic knowledge given to them from the exercises. Data was gathered on the students' subjective experiences with the class. This data and the class's overall performance were compared with past iterations of the course. New to the course was the Unreal Engine. Students used the latest version of the engine, Unreal Engine 4, to complete exercises. Not all students chose to use this engine for the team project. Instructor and students experiences with the engine were also recorded. While there were some problems implementing the engine within our lab environment, we were still able to execute the overall lesson plan. Even with the engine issues, the course had overall good performance. CGT 241, Introduction to 3D Animation, was shown to help the students to complete the course while CGT 215, Computer Graphics Programming I, did not provide enough information on game programming. Exercises were found to be helpful but students wanted a better understanding of how these skills can be applied to game development. Team projects

  10. Full-scale experiments with an ejector to reduce jet engine exhaust noise

    NASA Technical Reports Server (NTRS)

    Clark, B. J.

    1973-01-01

    Experiments with a modified J65 turbojet engine and ejector resulted in noise power reductions as large as 13 decibels in the low-frequency range. High-frequency noise power, which appeared to originate mainly from the mixing processes within the ejector, increased. Peak velocities at the ejector exit were reduced by one-half to two-thirds, although survey rakes showed that mixing was not complete. Acoustical lining inside the ejector would reduce the perceived noise level (in PNdB) by removing much of the high-frequency noise.

  11. Airborne laser topographic mapping results from initial joint NASA/US Army Corps of Engineers experiment

    NASA Technical Reports Server (NTRS)

    Krabill, W. B.; Collins, J. G.; Swift, R. N.; Butler, M. L.

    1980-01-01

    Initial results from a series of joint NASA/US Army Corps of Engineers experiments are presented. The NASA Airborne Oceanographic Lidar (AOL) was exercised over various terrain conditions, collecting both profile and scan data from which river basin cross sections are extracted. Comparisons of the laser data with both photogrammetry and ground surveys are made, with 12 to 27 cm agreement observed over open ground. Foliage penetration tests, utilizing the unique time-waveform sampling capability of the AOL, indicate 50 cm agreement with photogrammetry (known to have difficulty in foliage covered terrain).

  12. Cloning Nacre's 3D Interlocking Skeleton in Engineering Composites to Achieve Exceptional Mechanical Properties.

    PubMed

    Zhao, Hewei; Yue, Yonghai; Guo, Lin; Wu, Juntao; Zhang, Youwei; Li, Xiaodong; Mao, Shengcheng; Han, Xiaodong

    2016-07-01

    Ceramic/polymer composite equipped with 3D interlocking skeleton (3D IL) is developed through a simple freeze-casting method, exhibiting exceptionally light weight, high strength, toughness, and shock resistance. Long-range crack energy dissipation enabled by 3D interlocking structure is considered as the primary reinforcing mechanism for such superior properties. The smart composite design strategy should hold a place in developing future structural engineering materials.

  13. Engineering of the band gap and optical properties of thin films of yttrium hydride

    SciTech Connect

    You, Chang Chuan; Mongstad, Trygve; Maehlen, Jan Petter; Karazhanov, Smagul

    2014-07-21

    Thin films of oxygen-containing yttrium hydride show photochromic effect at room temperature. In this work, we have studied structural and optical properties of the films deposited at different deposition pressures, discovering the possibility of engineering the optical band gap by variation of the oxygen content. In sum, the transparency of the films and the wavelength range of photons triggering the photochromic effect can be controlled by variation of the deposition pressure.

  14. Strain engineering for mechanical properties in graphene nanoribbons revisited: The warping edge effect

    NASA Astrophysics Data System (ADS)

    Jiang, Jin-Wu

    2016-06-01

    We investigate the strain engineering and the edge effect for mechanical properties in graphene nanoribbons. The free edges of the graphene nanoribbons are warped due to compressive edge stresses. There is a structural transformation for the free edges from the three-dimensional warping configuration to the two-dimensional planar structure at the critical strain ɛc = 0.7%, at which the applied mechanical stress is equal to the intrinsic compressive edge stress. This structural transformation leads to step-like changes in several mechanical properties studied in the present work, including the Young's modulus, the Poisson's ratio, the quality factor of nanomechanical resonators, and the phonon edge mode.

  15. Tailoring the Spectroscopic Properties of Semiconductor Nanowires via Surface-Plasmon-Based Optical Engineering

    PubMed Central

    2014-01-01

    Semiconductor nanowires, due to their unique electronic, optical, and chemical properties, are firmly placed at the forefront of nanotechnology research. The rich physics of semiconductor nanowire optics arises due to the enhanced light–matter interactions at the nanoscale and coupling of optical modes to electronic resonances. Furthermore, confinement of light can be taken to new extremes via coupling to the surface plasmon modes of metal nanostructures integrated with nanowires, leading to interesting physical phenomena. This Perspective will examine how the optical properties of semiconductor nanowires can be altered via their integration with highly confined plasmonic nanocavities that have resulted in properties such as orders of magnitude faster and more efficient light emission and lasing. The use of plasmonic nanocavities for tailored optical absorption will also be discussed in order to understand and engineer fundamental optical properties of these hybrid systems along with their potential for novel applications, which may not be possible with purely dielectric cavities. PMID:25396030

  16. Engineering the Structure and Properties of DNA-Nanoparticle Superstructures Using Polyvalent Counterions.

    PubMed

    Chou, Leo Y T; Song, Fayi; Chan, Warren C W

    2016-04-06

    DNA assembly of nanoparticles is a powerful approach to control their properties and prototype new materials. However, the structure and properties of DNA-assembled nanoparticles are labile and sensitive to interactions with counterions, which vary with processing and application environment. Here we show that substituting polyamines in place of elemental counterions significantly enhanced the structural rigidity and plasmonic properties of DNA-assembled metal nanoparticles. These effects arose from the ability of polyamines to condense DNA and cross-link DNA-coated nanoparticles. We further used polyamine wrapped DNA nanostructures as structural templates to seed the growth of polymer multilayers via layer-by-layer assembly, and controlled the degree of DNA condensation, plasmon coupling efficiency, and material responsiveness to environmental stimuli by varying polyelectrolyte composition. These results highlight counterion engineering as a versatile strategy to tailor the properties of DNA-nanoparticle assemblies for various applications, and should be applicable to other classes of DNA nanostructures.

  17. Monitoring of the Physical and Chemical Properties of a Gasoline Engine Oil during Its Usage.

    PubMed

    Rahimi, Behnam; Semnani, Abolfazl; Nezamzadeh-Ejhieh, Alireza; Shakoori Langeroodi, Hamid; Hakim Davood, Massoud

    2012-01-01

    Physicochemical properties of a mineral-based gasoline engine oil have been monitored at 0, 500, 1000, 2000, 3500, 6000, 8500, and 11500 kilometer of operation. Tracing has been performed by inductively coupled plasma and some other techniques. At each series of measurements, the concentrations of twenty four elements as well as physical properties such as: viscosity at 40 and 100°C; viscosity index; flash point; pour point; specific gravity; color; total acid and base numbers; water content have been determined. The results are indicative of the decreasing trend in concentration of additive elements and increasing in concentration for wear elements. Different trends have been observed for various physical properties. The possible reasons for variations in physical and chemical properties have been discussed.

  18. Monitoring of the Physical and Chemical Properties of a Gasoline Engine Oil during Its Usage

    PubMed Central

    Rahimi, Behnam; Semnani, Abolfazl; Nezamzadeh-Ejhieh, Alireza; Shakoori Langeroodi, Hamid; Hakim Davood, Massoud

    2012-01-01

    Physicochemical properties of a mineral-based gasoline engine oil have been monitored at 0, 500, 1000, 2000, 3500, 6000, 8500, and 11500 kilometer of operation. Tracing has been performed by inductively coupled plasma and some other techniques. At each series of measurements, the concentrations of twenty four elements as well as physical properties such as: viscosity at 40 and 100°C; viscosity index; flash point; pour point; specific gravity; color; total acid and base numbers; water content have been determined. The results are indicative of the decreasing trend in concentration of additive elements and increasing in concentration for wear elements. Different trends have been observed for various physical properties. The possible reasons for variations in physical and chemical properties have been discussed. PMID:22567569

  19. Engineered particles demonstrate improved flow properties at elevated drug loadings for direct compression manufacturing.

    PubMed

    Trementozzi, Andrea N; Leung, Cheuk-Yui; Osei-Yeboah, Frederick; Irdam, Erwin; Lin, Yiqing; MacPhee, J Michael; Boulas, Pierre; Karki, Shyam B; Zawaneh, Peter N

    2017-03-08

    Optimizing powder flow and compaction properties are critical for ensuring a robust tablet manufacturing process. The impact of flow and compaction properties of the active pharmaceutical ingredient (API) becomes progressively significant for higher drug load formulations, and for scaling up manufacturing processes. This study demonstrated that flow properties of a powder blend can be improved through API particle engineering, without critically impacting blend tabletability at elevated drug loadings. In studying a jet milled API (D50=24μm) and particle engineered wet milled API (D50=70μm and 90μm), flow functions of all API lots were similarly poor despite the vast difference in average particle size (ffc<4). This finding strays from the common notion that powder flow properties are directly correlated to particle size distribution. Upon adding excipients, however, clear trends in flow functions based on API particle size were observed. Wet milled API blends had a much improved flow function (ffc>10) compared with the jet milled API blends. Investigation of the compaction properties of both wet and jet milled powder blends also revealed that both jet and wet milled material produced robust tablets at the drug loadings used. The ability to practically demonstrate this uncommon observation that similarly poor flowing APIs can lead to a marked difference upon blending is important for pharmaceutical development. It is especially important in early phase development during API selection, and is advantageous particularly when material-sparing techniques are utilized.

  20. Strain Engineering of Octahedral Rotations and Physical Properties of SrRuO3 Films.

    PubMed

    Lu, Wenlai; Song, Wendong; Yang, Ping; Ding, Jun; Chow, Gan Moog; Chen, Jingsheng

    2015-05-28

    Strain engineering is an effective way to modify functional properties of thin films. Recently, the importance of octahedral rotations in pervoskite films has been recognized in discovering and designing new functional phases. Octahedral behavior of SrRuO3 film as a popular electrode in heterostructured devices is of particular interest for its probable interfacial coupling of octahedra with the functional overlayers. Here we report the strain engineering of octahedral rotations and physical properties that has been achieved in SrRuO3 films in response to the substrate-induced misfit strains of almost the same amplitude but of opposite signs. It shows that the compressively strained film on NdGaO3 substrate displays a rotation pattern of a tetragonal phase whilst the tensilely strained film on KTaO3 substrate has the rotation pattern of the bulk orthorhombic SrRuO3 phase. In addition, the compressively strained film displays a perpendicular magnetic anisotropy while the tensilely strained film has the magnetic easy axis lying in the film plane. The results show the prospect of strain engineered octahedral architecture in producing desired property and novel functionality in the class of perovskite material.

  1. Strain Engineering of Octahedral Rotations and Physical Properties of SrRuO3 Films

    NASA Astrophysics Data System (ADS)

    Lu, Wenlai; Song, Wendong; Yang, Ping; Ding, Jun; Chow, Gan Moog; Chen, Jingsheng

    2015-05-01

    Strain engineering is an effective way to modify functional properties of thin films. Recently, the importance of octahedral rotations in pervoskite films has been recognized in discovering and designing new functional phases. Octahedral behavior of SrRuO3 film as a popular electrode in heterostructured devices is of particular interest for its probable interfacial coupling of octahedra with the functional overlayers. Here we report the strain engineering of octahedral rotations and physical properties that has been achieved in SrRuO3 films in response to the substrate-induced misfit strains of almost the same amplitude but of opposite signs. It shows that the compressively strained film on NdGaO3 substrate displays a rotation pattern of a tetragonal phase whilst the tensilely strained film on KTaO3 substrate has the rotation pattern of the bulk orthorhombic SrRuO3 phase. In addition, the compressively strained film displays a perpendicular magnetic anisotropy while the tensilely strained film has the magnetic easy axis lying in the film plane. The results show the prospect of strain engineered octahedral architecture in producing desired property and novel functionality in the class of perovskite material.

  2. The impact of low levels of collagen IX and pyridinoline on the mechanical properties of in vitro engineered cartilage.

    PubMed

    Yan, Dan; Zhou, Guangdong; Zhou, Xu; Liu, Wei; Zhang, Wen Jie; Luo, Xusong; Zhang, Lu; Jiang, Ting; Cui, Lei; Cao, Yilin

    2009-02-01

    The application of in vitro engineered cartilage has become a promising approach to repair cartilage defects. Nevertheless, the poor mechanical properties of in vitro engineered cartilage limit its potential for clinical applications. Studies have shown that the extracellular matrix (ECM) components are strongly correlated with the mechanical strength of engineered cartilage, but it remains unclear which components play a key role in determining the mechanical property of engineered cartilage. To address this issue, quantitative analyses of cartilage-specific components among native cartilage, in vivo and in vitro engineered cartilages were performed, and the correlation between various ECM molecules and Young's modulus was further analyzed. The results showed that many ECM molecules, such as highly sulphated glycosaminoglycan (GAG), collagens II, IX, and pyridinoline (PYR), contributed to the mechanical strength of cartilages. Further comparison between in vitro engineered cartilage and stress-stimulated in vitro engineered cartilage, known to have stronger mechanical properties, showed that only collagen IX and PYR, but not GAG and collagen II, were the key factors determining the mechanical properties of in vitro engineered cartilage. These results indicate that in vitro environment lacks the niche for enhancing collagen crosslinking that is mediated by collagen IX and PYR during cartilage formation. Thus, the discovery provides a clue for engineering strong cartilage in vitro in the future by enhancing the levels of these two molecules.

  3. Learning Experience and Socio-Cultural Influences on Female Engineering Students' Perspectives on Engineering Courses and Careers

    ERIC Educational Resources Information Center

    Balakrishnan, Balamuralithara; Low, Foon Siang

    2016-01-01

    As developed and developing countries move towards greater technological development in the 21st century, the need for engineers has increased substantially. Japan is facing the dilemma of insufficient engineers; therefore, the country has to rely on foreign workers. This problem may be resolved if there is a continuous effort to increase the…

  4. Experience gained from the application of basic quality assurance procedures in a Greek university engineering department

    NASA Astrophysics Data System (ADS)

    Stamatelos, A. M.

    2010-06-01

    During the last decade, significant funding has become available to Greek public universities to support the convergence to the common European space of higher education. In a number of departments, this funding was wisely invested in the development of a quality culture, covering not only the educational process, but also the services offered by the department's administration and technical support staff. This paper presents the design and implementation of a quality-oriented studies' reform plan in the Mechanical Engineering Department, University of Thessaly in the period 2002-2008. Based on the successful experience from its application, a significant part of the personnel and students have become acquainted with basic quality assurance procedures and performance evaluation. Experience and lessons learnt from this effort are reported and discussed in this paper.

  5. Engineered HA hydrogel for stem cell transplantation in the brain: Biocompatibility data using a design of experiment approach.

    PubMed

    Nih, Lina R; Moshayedi, Pouria; Llorente, Irene L; Berg, Andrew R; Cinkornpumin, Jessica; Lowry, William E; Segura, Tatiana; Carmichael, S Thomas

    2017-02-01

    This article presents data related to the research article "Systematic optimization of an engineered hydrogel allows for selective control of human neural stem cell survival and differentiation after transplantation in the stroke brain" (P. Moshayedi, L.R. Nih, I.L. Llorente, A.R. Berg, J. Cinkornpumin, W.E. Lowry et al., 2016) [1] and focuses on the biocompatibility aspects of the hydrogel, including its stiffness and the inflammatory response of the transplanted organ. We have developed an injectable hyaluronic acid (HA)-based hydrogel for stem cell culture and transplantation, to promote brain tissue repair after stroke. This 3D biomaterial was engineered to bind bioactive signals such as adhesive motifs, as well as releasing growth factors while supporting cell growth and tissue infiltration. We used a Design of Experiment approach to create a complex matrix environment in vitro by keeping the hydrogel platform and cell type constant across conditions while systematically varying peptide motifs and growth factors. The optimized HA hydrogel promoted survival of encapsulated human induced pluripotent stem cell derived-neural progenitor cells (iPS-NPCs) after transplantation into the stroke cavity and differentially tuned transplanted cell fate through the promotion of glial, neuronal or immature/progenitor states. The highlights of this article include: (1) Data of cell and bioactive signals addition on the hydrogel mechanical properties and growth factor diffusion, (2) the use of a design of Experiment (DOE) approach (M.W. 2 Weible and T. Chan-Ling, 2007) [2] to select multi-factorial experimental conditions, and (3) Inflammatory response and cell survival after transplantation.

  6. Recombination of protein fragments: a promising approach toward engineering proteins with novel nanomechanical properties.

    PubMed

    Balamurali, M M; Sharma, Deepak; Chang, Anderson; Khor, Dingyue; Chu, Ricky; Li, Hongbin

    2008-10-01

    Combining single molecule atomic force microscopy (AFM) and protein engineering techniques, here we demonstrate that we can use recombination-based techniques to engineer novel elastomeric proteins by recombining protein fragments from structurally homologous parent proteins. Using I27 and I32 domains from the muscle protein titin as parent template proteins, we systematically shuffled the secondary structural elements of the two parent proteins and engineered 13 hybrid daughter proteins. Although I27 and I32 are highly homologous, and homology modeling predicted that the hybrid daughter proteins fold into structures that are similar to that of parent protein, we found that only eight of the 13 daughter proteins showed beta-sheet dominated structures that are similar to parent proteins, and the other five recombined proteins showed signatures of the formation of significant alpha-helical or random coil-like structure. Single molecule AFM revealed that six recombined daughter proteins are mechanically stable and exhibit mechanical properties that are different from the parent proteins. In contrast, another four of the hybrid proteins were found to be mechanically labile and unfold at forces that are lower than the approximately 20 pN, as we could not detect any unfolding force peaks. The last three hybrid proteins showed interesting duality in their mechanical unfolding behaviors. These results demonstrate the great potential of using recombination-based approaches to engineer novel elastomeric protein domains of diverse mechanical properties. Moreover, our results also revealed the challenges and complexity of developing a recombination-based approach into a laboratory-based directed evolution approach to engineer novel elastomeric proteins.

  7. Design and implementation of the protective cap/biobarrier experiment at the Idaho National Engineering Laboratory

    SciTech Connect

    Limbach, W.E.; Ratzlaff, T.D.; Anderson, J.E.; Reynolds, T.D.; Laundre, J.W. |

    1994-12-31

    The Protective Cap/Biobarrier Experiment (PCBE), initiated in 1993 at the Idaho National Engineering Laboratory (INEL), is a strip-split plot experiment with three replications designed to rigorously test a 2.0-m loessal soil cap against a cap recommended by the US Environmental Protection Agency and two caps with biological intrusion barriers. Past research at INEL indicates that it should be possible to exclude water from buried wastes using natural materials and natural processes in arid environments rather than expensive materials (geotextiles) and highly engineered caps. The PCBE will also test the effects of two vegetal covers and three irrigation levels on cap performance. Drainage pans, located at the bottom of each plot, will monitor cap failure. Soil water profiles will be monitored biweekly by neutron probe and continuously by time domain reflectometry. The performance of each cap design will be monitored under a variety of conditions through 1998. From 1994 to 1996, the authors will assess plant establishment, rooting depths, patterns of moisture extraction and their interactions among caps, vegetal covers, and irrigation levels. In 1996, they will introduce ants and burrowing mammals to test the structural integrity of each cap design. In 1998, the authors will apply sufficient water to determine the failure limit for each cap design. The PCBE should provide reliable knowledge of the performances of the four cap designs under a variety of conditions and aid in making hazardous-waste management decisions at INEL and at disposal sites in similar environments.

  8. Engineering and management experience at Texas A&M Transportation Institute

    NASA Astrophysics Data System (ADS)

    Chowdhury, Arif Tahjibul

    This manuscript presents the author's engineering and management experience during his internship in the Materials and Pavements (M&P) Division at the Texas A&M Transportation Institute (TTI), and is a record of study for the Doctor of Engineering at Texas A&M University. Through this internship, he met his established internship objectives of gaining technical knowledge as well as knowledge and skills in project management, organizational communication, and quality management of pavement condition data, and of attaining professional development. In meeting these objectives, the author describes the history, mission, and organizational structure of his workplace. He also presents his experience of developing and delivering a two-week training course on pavement design and construction in Kosovo. Participating in a number of professional development training courses and other activities prepared him for working as an engineering manager. These activities include Delta-T leadership training, an instructor development course, a time management and organizational skills course, and the M&P Division lecture series. Leadership and skills learned through the Delta-T program were beneficial for the employee as well as the employer. For the class project, the author and his teammates performed a study dealing with improving TTI's deliverables. The Delta-T team composed a report summarizing their efforts of examining the current state of TTI's project deliverables, the deliverables' shortcomings, and potential enhancements to expand the deliverables' appeal to additional types of potential users outside the traditional research community. The team also developed a prototype web-based model of deliverables and presented some implementation recommendations. Participating in the Texas Department of Transportation's (TxDOT's) pavement surface distress data collection program enabled the author to become familiar with pavement distress data quality management and thus attain the

  9. Differential Experiences of Women and Minority Engineering Students in a Cooperative Education Program

    NASA Astrophysics Data System (ADS)

    Fifolt, Matthew M.; Abbott, Gypsy

    Although slight gains have been made in attracting women and minority students to the field of engineering, the differences are not great enough to meet current economic demands [National Academy of Sciences (2007). Rising above the gathering storm: Energizing and employing America for a brighter economic future, Washington, DC: National Academies Press]. Therefore, it has become imperative that colleges and universities increase efforts to both recruit and retain these students who express interest in the STEM fields [National Science Foundation (2006), Women, minorities, and persons with disabilities in science and engineering, NSF 4-311, Arlington, VA: NSF]. In engineering, one promising venue for students to gain professional experience as part of their undergraduate training is through cooperative education (co-op). However, there is a dearth of information in the research literature regarding how co-op programs can be structured to address the needs of diverse students. There is consensus, however, about one aspect of addressing the needs of diverse students, namely, mentoring and role models are key strategies for success. In this study, a mixed methods design was used to examine students' perceptions of mentoring in a cooperative education program in a southeastern university. Using Noe's [Noe, R. (1988). An investigation of the determinants of successful assigned mentoring relationships. Personnel Psychology, 1, 457-479] mentoring functions scales, which described psychosocial and career-related support, research findings indicated a statistically significant difference between gender and the psychosocial aspect of mentoring. Analysis of the qualitative data further confirmed differences in cooperative education experiences with respect to both gender and ethnicity.

  10. Combined Cycle Engine Large-Scale Inlet for Mode Transition Experiments: System Identification Rack Hardware Design

    NASA Technical Reports Server (NTRS)

    Thomas, Randy; Stueber, Thomas J.

    2013-01-01

    The System Identification (SysID) Rack is a real-time hardware-in-the-loop data acquisition (DAQ) and control instrument rack that was designed and built to support inlet testing in the NASA Glenn Research Center 10- by 10-Foot Supersonic Wind Tunnel. This instrument rack is used to support experiments on the Combined-Cycle Engine Large-Scale Inlet for Mode Transition Experiment (CCE? LIMX). The CCE?LIMX is a testbed for an integrated dual flow-path inlet configuration with the two flow paths in an over-and-under arrangement such that the high-speed flow path is located below the lowspeed flow path. The CCE?LIMX includes multiple actuators that are designed to redirect airflow from one flow path to the other; this action is referred to as "inlet mode transition." Multiple phases of experiments have been planned to support research that investigates inlet mode transition: inlet characterization (Phase-1) and system identification (Phase-2). The SysID Rack hardware design met the following requirements to support Phase-1 and Phase-2 experiments: safely and effectively move multiple actuators individually or synchronously; sample and save effector control and position sensor feedback signals; automate control of actuator positioning based on a mode transition schedule; sample and save pressure sensor signals; and perform DAQ and control processes operating at 2.5 KHz. This document describes the hardware components used to build the SysID Rack including their function, specifications, and system interface. Furthermore, provided in this document are a SysID Rack effectors signal list (signal flow); system identification experiment setup; illustrations indicating a typical SysID Rack experiment; and a SysID Rack performance overview for Phase-1 and Phase-2 experiments. The SysID Rack described in this document was a useful tool to meet the project objectives.

  11. Virtual laboratory: assessment of a b-learning experience for teaching Physics in Engineering

    NASA Astrophysics Data System (ADS)

    Ablanque, J.; Seidel, L.; Losada, J. C.

    2009-04-01

    During the autumn semester of 2008/09 term, we have carried out an experience of teaching an innovative subject at our University. The subject is open and elective for all the students at the University, most of them in Engineering degrees. We call it "Physics virtual laboratory ". The students use a CMS (course management system) for accessing the syllabus, and the materials for the course. These materials include videos, sound and rich text for describing some well known experiments in a Physics lab. They also have a test for each unit and have to submit a written essay for every experiment at a fixed date. They work with the help of the teacher that answer their questions and provide solutions for the exercises, so this course is not entirely e-learning, but rather blended learning. For every unit, we have prepared materials that serve as a guide for the experiment, without being physically at the laboratory and without measuring any physical quantities. All the necessary data are given, and the real apparatus are shown in videos embedded in the document and described in detail. The experiments chosen cover those found in a typical Physics lab: kinematics in an air-cushion rail, Boyle-Mariotte law, magnetic field inside a solenoid, simple circuits, lenses… The number is limited to seven experiments for time constraint reasons. In a given experiment, we put emphasis in quantifying the uncertainty of the results, and several ways of calculating it are explained in detail using Excel spreadsheets. After the subject has ended, we have gathered feedback from the students, and have taken note of how they rate it compared with more traditional subjects. Also, we assess our work and the usefulness of the materials and the fitness of the structure of the subject. This is important for assuring that the change in methodology is better for the learing process. In this communication we present the results of this assessment and try to reach some conclusions that might be

  12. Characterization of real gas properties for space shuttle main engine fuel turbine and performance calculations

    NASA Technical Reports Server (NTRS)

    Harloff, G. J.

    1986-01-01

    Real thermodynamic and transport properties of hydrogen, steam, the SSME mixture, and air are developed. The SSME mixture properties are needed for the analysis of the space shuttle main engine fuel turbine. The mixture conditions for the gases, except air, are presented graphically over a temperature range from 800 to 1200 K, and a pressure range from 1 to 500 atm. Air properties are given over a temperature range of 320 to 500 K, which are within the bounds of the thermodynamics programs used, in order to provide mixture data which is more easily checked (than H2/H2O). The real gas property variation of the SSME mixture is quantified. Polynomial expressions, needed for future computer analysis, for viscosity, Prandtl number, and thermal conductivity are given for the H2/H2O SSME fuel turbine mixture at a pressure of 305 atm over a range of temperatures from 950 to 1140 K. These conditions are representative of the SSME turbine operation. Performance calculations are presented for the space shuttle main engine (SSME) fuel turbine. The calculations use the air equivalent concept. Progress towards obtaining the capability to evaluate the performance of the SSME fuel turbine, with the H2/H2O mixture, is described.

  13. Adsorption laboratory experiment for undergraduate chemical engineering: Introducing kinetic, equilibrium and thermodynamic concepts

    NASA Astrophysics Data System (ADS)

    Muryanto, S.; Djatmiko Hadi, S.

    2016-11-01

    Adsorption laboratory experiment for undergraduate chemical engineering program is discussed. The experiment demonstrated adsorption of copper ions commonly found in wastewater using bio-sorbent, i.e. agricultural wastes. The adsorption was performed in a batch mode under various parameters: adsorption time (up to 120 min), initial pH (2 to 6), adsorbent dose (2.0 to 12.0 g L-1), adsorbent size (50 to 170 mesh), initial Cu2+ concentration (25 to 100 ppm) and temperatures (room temp to 40°C). The equilibrium and kinetic data of the experiments were calculated using the two commonly used isotherms: Langmuir and Lagergren pseudo-first-order kinetics. The maximum adsorption capacity for Cu2+ was found as 94.34 mg g-1. Thermodynamically, the adsorption process was spontaneous and endothermic. The calculated activation energy for the adsorption was observed as high as 127.94 kJ mol-1. Pedagogically, the experiment was assumed to be important in increasing student understanding of kinetic, equilibrium and thermodynamic concepts.

  14. Understanding the microstructure and properties of components fabricated by laser engineered net shaping (LENS)

    SciTech Connect

    GRIFFITH,MICHELLE L.; ENSZ,MARK T.; PUSKAR,JOSEPH D.; ROBINO,CHARLES V.; BROOKS,JOHN A.; PHILLIBER,JOEL A.; SMUGERESKY,JOHN E.; HOFMEISTER,W.H.

    2000-05-18

    Laser Engineered Net Shaping (LENS) is a novel manufacturing process for fabricating metal parts directly from Computer Aided Design (CAD) solid models. The process is similar to rapid prototyping technologies in its approach to fabricate a solid component by layer additive methods. However, the LENS technology is unique in that fully dense metal components with material properties that are similar to that of wrought materials can be fabricated. The LENS process has the potential to dramatically reduce the time and cost required realizing functional metal parts. In addition, the process can fabricate complex internal features not possible using existing manufacturing processes. The real promise of the technology is the potential to manipulate the material fabrication and properties through precision deposition of the material, which includes thermal behavior control, layered or graded deposition of multi-materials, and process parameter selection. This paper describes the authors' research to understand solidification aspects, thermal behavior, and material properties for laser metal deposition technologies.

  15. Unified low-parametrical equation of state for engineering calculations of thermodynamic properties of substances

    NASA Astrophysics Data System (ADS)

    Kaplun, Alexander; Meshalkin, Arkadiy

    2014-08-01

    The new simple semi empirical equation of state for description of P-ρ-T data of "normal" substances was specified. New equation of state has 10 individual adjustable coefficients and it describes thermal properties of gas, liquid and fluid in the main with the accuracy within the error of experimental data, except of critical region. The caloric properties and the speed of sound of argon, nitrogen and carbon dioxide were calculated with the help of known thermodynamic equations and in general divergences between calculated and tabular caloric data do not exceed the experimental error. New equation can be used for engineering calculations at the deficit of experimental data, especially on the caloric properties of substances.

  16. Development of Chitosan Scaffolds with Enhanced Mechanical Properties for Intestinal Tissue Engineering Applications.

    PubMed

    Zakhem, Elie; Bitar, Khalil N

    2015-10-13

    Massive resections of segments of the gastrointestinal (GI) tract lead to intestinal discontinuity. Functional tubular replacements are needed. Different scaffolds were designed for intestinal tissue engineering application. However, none of the studies have evaluated the mechanical properties of the scaffolds. We have previously shown the biocompatibility of chitosan as a natural material in intestinal tissue engineering. Our scaffolds demonstrated weak mechanical properties. In this study, we enhanced the mechanical strength of the scaffolds with the use of chitosan fibers. Chitosan fibers were circumferentially-aligned around the tubular chitosan scaffolds either from the luminal side or from the outer side or both. Tensile strength, tensile strain, and Young's modulus were significantly increased in the scaffolds with fibers when compared with scaffolds without fibers. Burst pressure was also increased. The biocompatibility of the scaffolds was maintained as demonstrated by the adhesion of smooth muscle cells around the different kinds of scaffolds. The chitosan scaffolds with fibers provided a better candidate for intestinal tissue engineering. The novelty of this study was in the design of the fibers in a specific alignment and their incorporation within the scaffolds.

  17. Development of Chitosan Scaffolds with Enhanced Mechanical Properties for Intestinal Tissue Engineering Applications

    PubMed Central

    Zakhem, Elie; Bitar, Khalil N.

    2015-01-01

    Massive resections of segments of the gastrointestinal (GI) tract lead to intestinal discontinuity. Functional tubular replacements are needed. Different scaffolds were designed for intestinal tissue engineering application. However, none of the studies have evaluated the mechanical properties of the scaffolds. We have previously shown the biocompatibility of chitosan as a natural material in intestinal tissue engineering. Our scaffolds demonstrated weak mechanical properties. In this study, we enhanced the mechanical strength of the scaffolds with the use of chitosan fibers. Chitosan fibers were circumferentially-aligned around the tubular chitosan scaffolds either from the luminal side or from the outer side or both. Tensile strength, tensile strain, and Young’s modulus were significantly increased in the scaffolds with fibers when compared with scaffolds without fibers. Burst pressure was also increased. The biocompatibility of the scaffolds was maintained as demonstrated by the adhesion of smooth muscle cells around the different kinds of scaffolds. The chitosan scaffolds with fibers provided a better candidate for intestinal tissue engineering. The novelty of this study was in the design of the fibers in a specific alignment and their incorporation within the scaffolds. PMID:26473937

  18. Fuel properties and engine performance of biodiesel from waste cooking oil collected in Dhaka city

    NASA Astrophysics Data System (ADS)

    Islam, R. B.; Islam, R.; Uddin, M. N.; Ehsan, Md.

    2016-07-01

    Waste cooking oil can be a potential source of biodiesel that has least effect on the edible oil consumption. Increasing number of hotel-restaurants and more active monitoring by health authorities have increased the generation of waste cooking oil significantly in densely populated cities like Dhaka. If not used or disposed properly, waste cooking oil itself may generate lot of environmental issues. In this work, waste cooking oils from different restaurants within Dhaka City were collected and some relevant properties of these waste oils were measured. Based on the samples studied one with the highest potential as biodiesel feed was identified and processed for engine performance. Standard trans-esterification process was used to produce biodiesel from the selected waste cooking oil. Biodiesel blends of B20 and B40 category were made and tested on a single cylinder direct injection diesel engine. Engine performance parameters included - bhp, bsfc and exhaust emission for rated and part load conditions. Results give a quantitative assessment of the potential of using biodiesel from waste cooking oil as fuel for diesel engines in Bangladesh.

  19. Is It "Writing on Water" or "Strike It Rich?" The Experiences of Prospective Teachers in Using Search Engines

    ERIC Educational Resources Information Center

    Sahin, Abdurrahman; Cermik, Hulya; Dogan, Birsen

    2010-01-01

    Information searching skills have become increasingly important for prospective teachers with the exponential growth of learning materials on the web. This study is an attempt to understand the experiences of prospective teachers with search engines through metaphoric images and to further investigate whether their experiences are related to the…

  20. The First-Year Experience of Non-Traditional Students in Danish Science and Engineering University Programmes

    ERIC Educational Resources Information Center

    Ulriksen, Lars; Madsen, Lene Møller; Holmegaard, Henriette Tolstrup

    2017-01-01

    To understand student drop-out from university, research must explore students' first-year experiences and the challenges they encounter. This article analyses the first-year experiences of non-traditional students in Danish science and engineering university programmes. Focusing on identity theory and the framework of integration processes…

  1. Emulation-Based Virtual Laboratories: A Low-Cost Alternative to Physical Experiments in Control Engineering Education

    ERIC Educational Resources Information Center

    Goodwin, G. C.; Medioli, A. M.; Sher, W.; Vlacic, L. B.; Welsh, J. S.

    2011-01-01

    This paper argues the case for emulation-based virtual laboratories in control engineering education. It demonstrates that such emulation experiments can give students an industrially relevant educational experience at relatively low cost. The paper also describes a particular emulation-based system that has been developed with the aim of giving…

  2. Tuning the optical, magnetic, and electrical properties of ReSe2 by nanoscale strain engineering.

    PubMed

    Yang, Shengxue; Wang, Cong; Sahin, Hasan; Chen, Hui; Li, Yan; Li, Shu-Shen; Suslu, Aslihan; Peeters, Francois M; Liu, Qian; Li, Jingbo; Tongay, Sefaattin

    2015-03-11

    Creating materials with ultimate control over their physical properties is vital for a wide range of applications. From a traditional materials design perspective, this task often requires precise control over the atomic composition and structure. However, owing to their mechanical properties, low-dimensional layered materials can actually withstand a significant amount of strain and thus sustain elastic deformations before fracture. This, in return, presents a unique technique for tuning their physical properties by "strain engineering". Here, we find that local strain induced on ReSe2, a new member of the transition metal dichalcogenides family, greatly changes its magnetic, optical, and electrical properties. Local strain induced by generation of wrinkle (1) modulates the optical gap as evidenced by red-shifted photoluminescence peak, (2) enhances light emission, (3) induces magnetism, and (4) modulates the electrical properties. The results not only allow us to create materials with vastly different properties at the nanoscale, but also enable a wide range of applications based on 2D materials, including strain sensors, stretchable electrodes, flexible field-effect transistors, artificial-muscle actuators, solar cells, and other spintronic, electromechanical, piezoelectric, photonic devices.

  3. Influence of normal loads and sliding velocities on friction properties of engineering plastics sliding against rough counterfaces

    NASA Astrophysics Data System (ADS)

    Nuruzzaman, D. M.; Chowdhury, M. A.; Rahaman, M. L.; Oumer, A. N.

    2016-02-01

    Friction properties of plastic materials are very important under dry sliding contact conditions for bearing applications. In the present research, friction properties of engineering plastics such as polytetrafluoroethylene (PTFE) and nylon are investigated under dry sliding contact conditions. In the experiments, PTFE and nylon slide against different rough counterfaces such as mild steel and stainless steel 316 (SS 316). Frictional tests are carried out at low loads 5, 7.5 and 10 N, low sliding velocities 0.5, 0.75 and 1 m/s and relative humidity 70%. The obtained results reveal that friction coefficient of PTFE increases with the increase in normal loads and sliding velocities within the observed range. On the other hand, frictional values of nylon decrease with the increase in normal loads and sliding velocities. It is observed that in general, these polymers show higher frictional values when sliding against SS 316 rather than mild steel. During running-in process, friction coefficient of PTFE and nylon steadily increases with the increase in rubbing time and after certain duration of rubbing, it remains at steady level. At identical operating conditions, the frictional values are significantly different depending on normal load, sliding velocity and material pair. It is also observed that in general, the influence of normal load on the friction properties of PTFE and nylon is greater than that of sliding velocity.

  4. Preparation and Properties of Bamboo Fiber/Nano-hydroxyapatite/Poly(lactic-co-glycolic) Composite Scaffold for Bone Tissue Engineering.

    PubMed

    Jiang, Liuyun; Li, Ye; Xiong, Chengdong; Su, Shengpei; Ding, Haojie

    2017-02-08

    In this study, bamboo fiber was first designed to incorporate into nano-hydroxyapatite/poly(lactic-co-glycolic) to obtain a new composite scaffold of bamboo fiber/nano-hydroxyapatite/poly(lactic-co- glycolic) (BF/n-HA/PLGA) by freeze-drying method. The effect of their components and some factors consisting of different freeze temperatures, concentrations, and pore-forming agents on the porous morphology, porosity, and compressive properties of the scaffold were investigated by scanning electron microscope, modified liquid displacement method, and electromechanical universal testing machine. The results indicated that the 5% BF/30% n-HA/PLGA composite scaffold, prepared with 5% (w/v) high concentration and frozen at -20 °C without pore-forming agent, had the best ideal porous structure and porosity as well as compressive properties, which far exceed those of n-HA/PLGA composite scaffold. In addition, the in vitro simulated body fluids soaking and cell culture experiment showed the addition of BF into the scaffold accelerated the BF/n-HA/PLGA composite scaffolds degradation and exhibited good cytocompatibility, including attachment and proliferation. All the results of the study show that BF has improved the properties of n-HA/PLGA composite scaffolds and BF/n-HA/PLGA might have a great potential for bone tissue engineering scaffold.

  5. Engineering the Mechanical Properties of Monolayer Graphene Oxide at the Atomic Level.

    PubMed

    Soler-Crespo, Rafael A; Gao, Wei; Xiao, Penghao; Wei, Xiaoding; Paci, Jeffrey T; Henkelman, Graeme; Espinosa, Horacio D

    2016-07-21

    The mechanical properties of graphene oxide (GO) are of great importance for applications in materials engineering. Previous mechanochemical studies of GO typically focused on the influence of the degree of oxidation on the mechanical behavior. In this study, using density functional-based tight binding simulations, validated using density functional theory simulations, we reveal that the deformation and failure of GO are strongly dependent on the relative concentrations of epoxide (-O-) and hydroxyl (-OH) functional groups. Hydroxyl groups cause GO to behave as a brittle material; by contrast, epoxide groups enhance material ductility through a mechanically driven epoxide-to-ether functional group transformation. Moreover, with increasing epoxide group concentration, the strain to failure and toughness of GO significantly increases without sacrificing material strength and stiffness. These findings demonstrate that GO should be treated as a versatile, tunable material that may be engineered by controlling chemical composition, rather than as a single, archetypical material.

  6. Rheological Properties of Cross-Linked Hyaluronan–Gelatin Hydrogels for Tissue Engineering

    PubMed Central

    Vanderhooft, Janssen L.; Alcoutlabi, Mataz; Magda, Jules J.; Prestwich, Glenn D.

    2009-01-01

    Hydrogels that mimic the natural extracellular matrix (ECM) are used in three-dimensional cell culture, cell therapy, and tissue engineering. A semi-synthetic ECM based on cross-linked hyaluronana offers experimental control of both composition and gel stiffness. The mechanical properties of the ECM in part determine the ultimate cell phenotype. We now describe a rheological study of synthetic ECM hydrogels with storage shear moduli that span three orders of magnitude, from 11 to 3 500 Pa, a range important for engineering of soft tissues. The concentration of the chemically modified HA and the cross-linking density were the main determinants of gel stiffness. Increase in the ratio of thiol-modified gelatin reduced gel stiffness by diluting the effective concentration of the HA component. PMID:18839402

  7. Dynamic Testing of the NASA Hypersonic Project Combined Cycle Engine Testbed for Mode Transition Experiments

    NASA Technical Reports Server (NTRS)

    2011-01-01

    NASA is interested in developing technology that leads to more routine, safe, and affordable access to space. Access to space using airbreathing propulsion systems has potential to meet these objectives based on Airbreathing Access to Space (AAS) system studies. To this end, the NASA Fundamental Aeronautics Program (FAP) Hypersonic Project is conducting fundamental research on a Turbine Based Combined Cycle (TBCC) propulsion system. The TBCC being studied considers a dual flow-path inlet system. One flow-path includes variable geometry to regulate airflow to a turbine engine cycle. The turbine cycle provides propulsion from take-off to supersonic flight. The second flow-path supports a dual-mode scramjet (DMSJ) cycle which would be initiated at supersonic speed to further accelerate the vehicle to hypersonic speed. For a TBCC propulsion system to accelerate a vehicle from supersonic to hypersonic speed, a critical enabling technology is the ability to safely and effectively transition from the turbine to the DMSJ-referred to as mode transition. To experimentally test methods of mode transition, a Combined Cycle Engine (CCE) Large-scale Inlet testbed was designed with two flow paths-a low speed flow-path sized for a turbine cycle and a high speed flow-path designed for a DMSJ. This testbed system is identified as the CCE Large-Scale Inlet for Mode Transition studies (CCE-LIMX). The test plan for the CCE-LIMX in the NASA Glenn Research Center (GRC) 10- by 10-ft Supersonic Wind Tunnel (10x10 SWT) is segmented into multiple phases. The first phase is a matrix of inlet characterization (IC) tests to evaluate the inlet performance and establish the mode transition schedule. The second phase is a matrix of dynamic system identification (SysID) experiments designed to support closed-loop control development at mode transition schedule operating points for the CCE-LIMX. The third phase includes a direct demonstration of controlled mode transition using a closed loop control

  8. Chondroprotective supplementation promotes the mechanical properties of injectable scaffold for human nucleus pulposus tissue engineering.

    PubMed

    Foss, Berit L; Maxwell, Thomas W; Deng, Ying

    2014-01-01

    A result of intervertebral disc (IVD) degeneration, the nucleus pulposus (NP) is no longer able to withstand applied load leading to pain and disability. The objective of this study is to fabricate a tissue-engineered injectable scaffold with chondroprotective supplementation in vitro to improve the mechanical properties of a degenerative NP. Tissue-engineered scaffolds were fabricated using different concentrations of alginate and calcium chloride and mechanically evaluated. Fabrication conditions were based on structural and mechanical resemblance to the native NP. Chondroprotective supplementation, glucosamine (GCSN) and chondroitin sulfate (CS), were added to scaffolds at concentrations of 0:0µg/mL (0:0-S), 125:100µg/mL (125:100-S), 250:200µg/mL (250:200-S), and 500:400µg/mL (500:400-S), GCSN and CS, respectively. Scaffolds were used to fabricate tissue-engineered constructs through encapsulation of human nucleus pulposus cells (HNPCs). The tissue-engineered constructs were collected at days 1, 14, and 28 for biochemical and biomechanical evaluations. Confocal microscopy showed HNPC viability and rounded morphology over the 28 day period. MTT analysis resulted in significant increases in cell proliferation for each group. Collagen type II ELISA quantification and compressive aggregate moduli (HA) showed increasing trends for both 250:200-S and the 500:400-S groups on Day 28 with significantly greater HA compared to 0:0-S group. Glycosaminoglycan and water content decreased for all groups. Results indicate the increased mechanical properties of the 250:200-S and the 500:400-S was due to production of a functional matrix. This study demonstrated potential for a chondroprotective supplemented injectable scaffold to restore biomechanical function of a degenerative disc through the production of a mechanically functional matrix.

  9. Fuel property effects on USAF gas turbine engine combustors and afterburners

    NASA Technical Reports Server (NTRS)

    Reeves, C. M.

    1984-01-01

    Since the early 1970s, the cost and availability of aircraft fuel have changed drastically. These problems prompted a program to evaluate the effects of broadened specification fuels on current and future aircraft engine combustors employed by the USAF. Phase 1 of this program was to test a set of fuels having a broad range of chemical and physical properties in a select group of gas turbine engine combustors currently in use by the USAF. The fuels ranged from JP4 to Diesel Fuel number two (DF2) with hydrogen content ranging from 14.5 percent down to 12 percent by weight, density ranging from 752 kg/sq m to 837 kg/sq m, and viscosity ranging from 0.830 sq mm/s to 3.245 sq mm/s. In addition, there was a broad range of aromatic content and physical properties attained by using Gulf Mineral Seal Oil, Xylene Bottoms, and 2040 Solvent as blending agents in JP4, JP5, JP8, and DF2. The objective of Phase 2 was to develop simple correlations and models of fuel effects on combustor performance and durability. The major variables of concern were fuel chemical and physical properties, combustor design factors, and combustor operating conditions.

  10. Metrological traceability of the measured values of properties of engineering materials

    NASA Astrophysics Data System (ADS)

    Roebben, G.; Linsinger, T.; Lamberty, A.; Emons, H.

    2010-04-01

    Global comparability of the measured values of material properties is based on some fundamental metrological concepts. These concepts are either already widely implemented in current procedures for materials testing or they are being further developed and increasingly accepted and used. An important aspect of the comparability of measurement results is metrological traceability. This paper aims at illustrating with practical examples how to apply the concept of metrological traceability as defined in ISO/IEC Guide 99:2007, known also as the VIM (International Vocabulary of Metrology), in the field of engineering material properties. VIM distinguishes three different types of references for traceability: either to a system of units, such as the SI, to a measurement procedure or to a physical measurement standard. For each approach, an example is given in the field of engineering material properties, including appropriate traceability statements and means to achieve the traceability. The role of certified reference materials is highlighted, as well as practical consequences of traceability requirements for the design of reference material certification projects.

  11. Synthesis and Engineering Materials Properties of Fluid Phase Chemical Hydrogen Storage Materials for Automotive Applications

    SciTech Connect

    Choi, Young Joon; Westman, Matthew P.; Karkamkar, Abhijeet J.; Chun, Jaehun; Ronnebro, Ewa

    2015-09-01

    Among candidates for chemical hydrogen storage in PEM fuel cell automotive applications, ammonia borane (AB, NH3BH3) is considered to be one of the most promising materials due to its high practical hydrogen content of 14-16 wt%. This material is selected as a surrogate chemical for a hydrogen storage system. For easier transition to the existing infrastructure, a fluid phase hydrogen storage material is very attractive and thus, we investigated the engineering materials properties of AB in liquid carriers for a chemical hydrogen storage slurry system. Slurries composed of AB and high temperature liquids were prepared by mechanical milling and sonication in order to obtain stable and fluidic properties. Volumetric gas burette system was adopted to observe the kinetics of the H2 release reactions of the AB slurry and neat AB. Viscometry and microscopy were employed to further characterize slurries engineering properties. Using a tip-sonication method we have produced AB/silicone fluid slurries at solid loadings up to 40wt% (6.5wt% H2) with viscosities less than 500cP at 25°C.

  12. Accelerator Technology and High Energy Physics Experiments, Photonics Applications and Web Engineering, Wilga, May 2012

    NASA Astrophysics Data System (ADS)

    Romaniuk, Ryszard S.

    2012-05-01

    The paper is the second part (out of five) of the research survey of WILGA Symposium work, May 2012 Edition, concerned with accelerator technology and high energy physics experiments. It presents a digest of chosen technical work results shown by young researchers from different technical universities from this country during the XXXth Jubilee SPIE-IEEE Wilga 2012, May Edition, symposium on Photonics and Web Engineering. Topical tracks of the symposium embraced, among others, nanomaterials and nanotechnologies for photonics, sensory and nonlinear optical fibers, object oriented design of hardware, photonic metrology, optoelectronics and photonics applications, photonicselectronics co-design, optoelectronic and electronic systems for astronomy and high energy physics experiments, JET and pi-of-the sky experiments development. The symposium is an annual summary in the development of numerable Ph.D. theses carried out in this country in the area of advanced electronic and photonic systems. It is also a great occasion for SPIE, IEEE, OSA and PSP students to meet together in a large group spanning the whole country with guests from this part of Europe. A digest of Wilga references is presented [1-275].

  13. Acoustic interactions between an altitude test facility and jet engine plumes: Theory and experiments

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Jones, R. R., III; Tam, C. K.; Massey, K. C.; Fleming, A. J.

    1992-01-01

    The overall objective of the described effort was to develop an understanding of the physical mechanisms involved in the flow/acoustic interactions experienced in full-scale altitude engine test facilities. This is done by conducting subscale experiments and through development of a theoretical model. Model cold jet experiments with an axisymmetric convergent nozzle are performed in a test setup that stimulates a supersonic jet exhausting into a cylindrical diffuser. The measured data consist of detailed flow visualization data and acoustic spectra for a free and a ducted plume. It is shown that duct resonance is most likely responsible by theoretical calculations. Theoretical calculations also indicate that the higher discrete tones observed in the measurements are related to the screech phenomena. Limited experiments on the sensitivity of a free 2-D, C-D nozzle to externally imposed sound are also presented. It is shown that a 2-D, C-D nozzle with a cutback is less excitable than a 2-D C-D nozzle with no cutback. At a pressure ratio of 1.5 unsteady separation from the diverging walls of the nozzle is noticed. This separation switches from one wall to the opposite wall thus providing an unsteady deflection of the plume. It is shown that this phenomenon is related to the venting provided by the cutback section.

  14. Modelling and Inverse-Modelling: Experiences with O.D.E. Linear Systems in Engineering Courses

    ERIC Educational Resources Information Center

    Martinez-Luaces, Victor

    2009-01-01

    In engineering careers courses, differential equations are widely used to solve problems concerned with modelling. In particular, ordinary differential equations (O.D.E.) linear systems appear regularly in Chemical Engineering, Food Technology Engineering and Environmental Engineering courses, due to the usefulness in modelling chemical kinetics,…

  15. The Lived Experiences of Professional Engineers over the Life-Cycle of a Technological Device

    ERIC Educational Resources Information Center

    Gandara, Guillermo F.

    2012-01-01

    One of the goals of this study was to pose the engineering role in a way that allows engineers to understand the impact that professional requirements have on their career. For engineers making medical devices, requirements come from three principal sources, professional engineering, regulatory agencies, and their own organization. Engineering…

  16. Knowledge Gained from Practical Experience in the Designing of Aircraft Engines

    NASA Technical Reports Server (NTRS)

    Kurtz, Oskar

    1933-01-01

    The present report examines a few important points of engine design such as: in-line water cooled engines, air-cooled in-line engines, and air-cooled radial engines. Subassemblies are also discussed like cylinder types, blower driving gears, pistons, valves, bearings, and crankshafts.

  17. Engineering biodegradable polyester elastomers with antioxidant properties to attenuate oxidative stress in tissues

    PubMed Central

    van Lith, R.; Gregory, E.K.; Yang, J.; Kibbe, M.R.; Ameer, G.A.

    2014-01-01

    Oxidative stress plays an important role in the limited biological compatibility of many biomaterials due to inflammation, as well as in various pathologies including atherosclerosis and restenosis as a result of vascular interventions. Engineering antioxidant properties into a material is therefore a potential avenue to improve the biocompatibility of materials, as well as to locally attenuate oxidative stress-related pathologies. Moreover, biodegradable polymers that have antioxidant properties built into their backbone structure have high relative antioxidant content and may provide prolonged, continuous attenuation of oxidative stress while the polymer or its degradation products are present. In this report, we describe the synthesis of poly(1,8-octanediol-co-citrate-co-ascorbate) (POCA), a citric-acid based biodegradable elastomer with native, intrinsic antioxidant properties. The in vitro antioxidant activity of POCA as well as its effects on vascular cells in vitro and in vivo were studied. Antioxidant properties investigated included scavenging of free radicals, iron chelation and the inhibition of lipid peroxidation. POCA reduced reactive oxygen species generation in cells after an oxidative challenge and protected cells from oxidative stress-induced cell death. Importantly, POCA antioxidant properties remained present upon degradation. Vascular cells cultured on POCA showed high viability, and POCA selectively inhibited smooth muscle cell proliferation, while supporting endothelial cell proliferation. Finally, preliminary data on POCA-coated ePTFE grafts showed reduced intimal hyperplasia when compared to standard ePTFE grafts. This biodegradable, intrinsically antioxidant polymer may be useful for tissue engineering application where oxidative stress is a concern. PMID:24976244

  18. Morphology and Optical Properties of Black-Carbon Particles Relevant to Engine Emissions

    NASA Astrophysics Data System (ADS)

    Michelsen, H. A.; Bambha, R.; Dansson, M. A.; Schrader, P. E.

    2013-12-01

    Black-carbon particles are believed to have a large influence on climate through direct radiative forcing, reduction of surface albedo of snow and ice in the cryosphere, and interaction with clouds. The optical properties and morphology of atmospheric particles containing black carbon are uncertain, and characterization of black carbon resulting from engines emissions is needed. Refractory black-carbon particles found in the atmosphere are often coated with unburned fuel, sulfuric acid, water, ash, and other combustion by-products and atmospheric constituents. Coatings can alter the optical and physical properties of the particles and therefore change their optical properties and cloud interactions. Details of particle morphology and coating state can also have important effects on the interpretation of optical diagnostics. A more complete understanding of how coatings affect extinction, absorption, and incandescence measurements is needed before these techniques can be applied reliably to a wide range of particles. We have investigated the effects of coatings on the optical and physical properties of combustion-generated black-carbon particles using a range of standard particle diagnostics, extinction, and time-resolved laser-induced incandescence (LII) measurements. Particles were generated in a co-flow diffusion flame, extracted, cooled, and coated with oleic acid. The diffusion flame produces highly dendritic soot aggregates with similar properties to those produced in diesel engines, diffusion flames, and most natural combustion processes. A thermodenuder was used to remove the coating. A scanning mobility particle sizer (SMPS) was used to monitor aggregate sizes; a centrifugal particle mass analyzer (CPMA) was used to measure coating mass fractions, and transmission electron microscopy (TEM) was used to characterize particle morphologies. The results demonstrate important differences in optical measurements between coated and uncoated particles.

  19. Engineering biodegradable polyester elastomers with antioxidant properties to attenuate oxidative stress in tissues.

    PubMed

    van Lith, Robert; Gregory, Elaine K; Yang, Jian; Kibbe, Melina R; Ameer, Guillermo A

    2014-09-01

    Oxidative stress plays an important role in the limited biological compatibility of many biomaterials due to inflammation, as well as in various pathologies including atherosclerosis and restenosis as a result of vascular interventions. Engineering antioxidant properties into a material is therefore a potential avenue to improve the biocompatibility of materials, as well as to locally attenuate oxidative stress-related pathologies. Moreover, biodegradable polymers that have antioxidant properties built into their backbone structure have high relative antioxidant content and may provide prolonged, continuous attenuation of oxidative stress while the polymer or its degradation products are present. In this report, we describe the synthesis of poly(1,8-octanediol-co-citrate-co-ascorbate) (POCA), a citric-acid based biodegradable elastomer with native, intrinsic antioxidant properties. The in vitro antioxidant activity of POCA as well as its effects on vascular cells in vitro and in vivo were studied. Antioxidant properties investigated included scavenging of free radicals, iron chelation and the inhibition of lipid peroxidation. POCA reduced reactive oxygen species generation in cells after an oxidative challenge and protected cells from oxidative stress-induced cell death. Importantly, POCA antioxidant properties remained present upon degradation. Vascular cells cultured on POCA showed high viability, and POCA selectively inhibited smooth muscle cell proliferation, while supporting endothelial cell proliferation. Finally, preliminary data on POCA-coated ePTFE grafts showed reduced intimal hyperplasia when compared to standard ePTFE grafts. This biodegradable, intrinsically antioxidant polymer may be useful for tissue engineering application where oxidative stress is a concern.

  20. Hyaluronic acid enhances the mechanical properties of tissue-engineered cartilage constructs.

    PubMed

    Levett, Peter A; Hutmacher, Dietmar W; Malda, Jos; Klein, Travis J

    2014-01-01

    There is a need for materials that are well suited for cartilage tissue engineering. Hydrogels have emerged as promising biomaterials for cartilage repair, since, like cartilage, they have high water content, and they allow cells to be encapsulated within the material in a genuinely three-dimensional microenvironment. In this study, we investigated the mechanical properties of tissue-engineered cartilage constructs using in vitro culture models incorporating human chondrocytes from osteoarthritis patients. We evaluated hydrogels formed from mixtures of photocrosslinkable gelatin-methacrylamide (Gel-MA) and varying concentrations (0-2%) of hyaluronic acid methacrylate (HA-MA). Initially, only small differences in the stiffness of each hydrogel existed. After 4 weeks of culture, and to a greater extent 8 weeks of culture, HA-MA had striking and concentration dependent impact on the changes in mechanical properties. For example, the initial compressive moduli of cell-laden constructs with 0 and 1% HA-MA were 29 and 41 kPa, respectively. After 8 weeks of culture, the moduli of these constructs had increased to 66 and 147 kPa respectively, representing a net improvement of 69 kPa for gels with 1% HA-MA. Similarly the equilibrium modulus, dynamic modulus, failure strength and failure strain were all improved in constructs containing HA-MA. Differences in mechanical properties did not correlate with glycosaminoglycan content, which did not vary greatly between groups, yet there were clear differences in aggrecan intensity and distribution as assessed using immunostaining. Based on the functional development with time in culture using human chondrocytes, mixtures of Gel-MA and HA-MA are promising candidates for cartilage tissue-engineering applications.

  1. The ACCEND program: a combined BS and MS program in environmental engineering that includes co-operative work experience.

    PubMed

    Bishop, P L; Keener, T C; Kukreti, A R; Kowel, S T

    2004-01-01

    Environmental engineering education has rapidly expanded in recent years and new teaching methods are needed. Many professionals and educators believe that a MS degree in environmental engineering should be the minimum in order to practice the profession, along with practical training. This paper describes an innovative program being offered at the University of Cincinnati that combines an integrated BS in civil engineering and an MS in environmental engineering with extensive practical co-operative education (co-op) experience, all within a five-year period. The program includes distance learning opportunities during the co-op periods. The result is a well-trained graduate who will receive higher pay and more challenging career opportunities, and who will have developed professionalism and maturity beyond that from traditional engineering programs.

  2. Upper Stage Flight Experiment 10K Engine Design and Test Results

    NASA Technical Reports Server (NTRS)

    Ross, R.; Morgan, D.; Crockett, D.; Martinez, L.; Anderson, W.; McNeal, C.

    2000-01-01

    A 10,000 lbf thrust chamber was developed for the Upper Stage Flight Experiment (USFE). This thrust chamber uses hydrogen peroxide/JP-8 oxidizer/fuel combination. The thrust chamber comprises an oxidizer dome and manifold, catalyst bed assembly, fuel injector, and chamber/nozzle assembly. Testing of the engine was done at NASA's Stennis Space Center (SSC) to verify its performance and life for future upper stage or Reusable Launch Vehicle applications. Various combinations of silver screen catalyst beds, fuel injectors, and combustion chambers were tested. Results of the tests showed high C* efficiencies (97% - 100%) and vacuum specific impulses of 275 - 298 seconds. With fuel film cooling, heating rates were low enough that the silica/quartz phenolic throat experienced minimal erosion. Mission derived requirements were met, along with a perfect safety record.

  3. Isothermal Dendritic Growth Experiment - Science, engineering, and hardware development for USMP space flights

    NASA Technical Reports Server (NTRS)

    Glicksman, M. E.; Hahn, R. C.; Koss, M. B.; Tirmizi, S. H.; Selleck, M. E.; Velosa, A.; Winsa, E.

    1991-01-01

    The Isothermal Dendritic Growth Experiment (IDGE) has been designed to provide microgravity data on dendritic growth for a critical test of theory. This paper updates progress on constructing a crystal growth chamber suitable for space flight. The IDGE chamber is constructed from glass and stainless steel and is hermetically sealed by electron beam welds and glass-metal seals. Initial tests of the chambers sample's melting point plateau show that the new chamber design is capable of preserving the 99.9995 percent purity of succinonitrile. Dendrite growth can be initiated in the center of the IDGE chamber by means of thermo-electric coolers and a capillary injector tube (stinger). The new IDGE chamber is ready for fully integrated tests with the prototype IDGE engineering hardware at NASA's Lewis Research Center.

  4. Simple Experiment for Studying the Properties of a Ferromagnetic Material.

    ERIC Educational Resources Information Center

    Sood, B. R.; And Others

    1980-01-01

    Describes an undergraduate physics experiment for studying Curie temperature and Curie constant of a ferromagnetic material. The exchange field (Weiss field) has been estimated by using these parameters. (HM)

  5. Cloud microphysical properties of convective clouds sampled during the Convective Precipitation Experiment (COPE) experiment.

    NASA Astrophysics Data System (ADS)

    Jackson, R.; French, J.; Leon, D.; Plummer, D. M.; Lasher-Trapp, S.; Blyth, A. M.

    2015-12-01

    The COnvective Precipitation Experiment (COPE), occurring in the southwest UK during Summer 2013, was motivated to improve quantitative precipitation forecasting, in part, with the aim to increase understanding of the warm and cold precipitation processes that can produce heavy convective rainfall in the southwest UK. In particular, we examine the creation of graupel embryos, the Hallett-Mossop process, and the effect of entrainment on these processes. To characterize the evolution of cloud microphysical properties of maturing thunderstorms, the University of Wyoming King Air sampled the tops of fresh turrets between -15 and 0. Data sampled by the Cloud Droplet Probe, Cloud Imaging grayscale Probe (CIP-Grey) and 2D Precipitation Probe during four missions are examined. Here we characterize the variability of the cloud liquid and ice particle size distributions and liquid water contents (LWC) inside updraft cores, as a function of temperature, T, and vertical velocity, w. On one of the days, the number concentration of particles with maximum dimension D > 300 μm, N>300, was less than 1 L-1, with very few ice hydrometeors observed. However, on the other missions, N>300 ranged from 1 L-1 to 250 L-1. The CIP-Grey detected liquid drops at T > -5 and a mixture of graupel and rimed columns at T < -5 for these missions, consistent with the warm rain process providing the frozen drops necessary to form graupel embryos that initiate secondary production. In general, LWC relative to adiabatic decreased from 0.75 to 0.2 with height and was lowest when N>300 > 1 L-1, consistent with precipitation growth by collision-coalescence and accretion. Finally, ice precipitation was primarily present at w < 7 m s-1 and greatest when w < 3 m s-1, suggesting that w influences the number of ice particles generated in the updraft cores sampled during COPE-MED.

  6. Modulations of thermal properties of graphene by strain-induced phonon engineering

    NASA Astrophysics Data System (ADS)

    Tada, Kento; Funatani, Takashi; Konabe, Satoru; Sasaoka, Kenji; Ogawa, Matsuto; Souma, Satofumi; Yamamoto, Takahiro

    2017-02-01

    Modulation of the thermal properties of graphene due to strain-induced phononic band engineering was theoretically investigated by first-principles calculations based on the density functional theory. The high-energy phonon modes are found to exhibit softening owing to the strain, whereas a low-energy acoustic mode (out-of-plane mode) exhibits hardening. Moreover, the dispersion relation of the out-of-plane mode associated with the strain essentially changes from quadratic (∝ k 2) to linear (∝ k). Accordingly, the temperature dependence of the low-temperature specific heat also changes from linear (∝ T) to quadratic (∝ T 2).

  7. Controlling thermal and electrical properties of graphene by strain-engineering its flexural phonons

    NASA Astrophysics Data System (ADS)

    Conley, Hiram; Nicholl, Ryan; Bolotin, Kirill

    2014-03-01

    We explore the effects of flexural phonons on the thermal and electrical properties of graphene. To control the amplitude of flexural phonons, we developed a technique to engineer uniform mechanical strain between 0 and 1% in suspended graphene. We determine the level of strain, thermal conductivity and carrier mobility of graphene through a combination of mechanical resonance and electrical transport measurements. Depending on strain, we find significant changes in the thermal expansion coefficient, thermal conductivity, and carrier mobility of suspended graphene. These changes are consistent with the expected contribution of flexural phonons.

  8. Fuel property effects on fuel/air mixing in an experimental diesel engine

    SciTech Connect

    Browne, K.R.; Patridge, I.M.; Greeves, G.

    1986-01-01

    Fuels of widely varying properties are studied by injection of a single and well defined spray into an experimental diesel engine. Three optical techniques were developed to visualise liquid fuel, fuel vapour, flame, soot and individual droplets and their associated vapour trails. Liquid core length measurements are presented for diesel fuel, toluene, ethanol and sunflower oil. Computer model predictions show that an increase of the fuel mid-boiling point by 40/sup 0/C gives a similar effect on liquid core length to an increase of 0.03mm in the nozzle hole diameter.

  9. CMC Property Variability and Life Prediction Methods for Turbine Engine Component Application

    NASA Technical Reports Server (NTRS)

    Cheplak, Matthew L.

    2004-01-01

    The ever increasing need for lower density and higher temperature-capable materials for aircraft engines has led to the development of Ceramic Matrix Composites (CMCs). Today's aircraft engines operate with >3000"F gas temperatures at the entrance to the turbine section, but unless heavily cooled, metallic components cannot operate above approx.2000 F. CMCs attempt to push component capability to nearly 2700 F with much less cooling, which can help improve engine efficiency and performance in terms of better fuel efficiency, higher thrust, and reduced emissions. The NASA Glenn Research Center has been researching the benefits of the SiC/SiC CMC for engine applications. A CMC is made up of a matrix material, fibers, and an interphase, which is a protective coating over the fibers. There are several methods or architectures in which the orientation of the fibers can be manipulated to achieve a particular material property objective as well as a particular component geometric shape and size. The required shape manipulation can be a limiting factor in the design and performance of the component if there is a lack of bending capability of the fiber as making the fiber more flexible typically sacrifices strength and other fiber properties. Various analysis codes are available (pcGINA, CEMCAN) that can predict the effective Young's Moduli, thermal conductivities, coefficients of thermal expansion (CTE), and various other properties of a CMC. There are also various analysis codes (NASAlife) that can be used to predict the life of CMCs under expected engine service conditions. The objective of this summer study is to utilize and optimize these codes for examining the tradeoffs between CMC properties and the complex fiber architectures that will be needed for several different component designs. For example, for the pcGINA code, there are six variations of architecture available. Depending on which architecture is analyzed, the user is able to specify the fiber tow size, tow

  10. The first frontier: High altitude ballooning as a platform for student research experiences in science and engineering

    NASA Astrophysics Data System (ADS)

    Larson, Shane L.; Armstrong, John C.; Hiscock, William A.

    2009-06-01

    High altitude balloon platforms are ideal for providing hands-on research experiences for students in physics, atmospheric science, engineering, and other aerospace-related disciplines. We describe a basic high altitude balloon platform that can be constructed and operated by undergraduate students. The existing HARBOR and BOREALIS programs are used to illustrate some possible science and engineering research projects that students can pursue as part of a high-altitude flight program.

  11. Replication of engine block cylinder bridge microstructure and mechanical properties with lab scale 319 Al alloy billet castings

    SciTech Connect

    Lombardi, A.; D'Elia, F.; Ravindran, C.; MacKay, R.

    2014-01-15

    In recent years, aluminum alloy gasoline engine blocks have in large part successfully replaced nodular cast iron engine blocks, resulting in improved vehicle fuel efficiency. However, because of the inadequate wear resistance properties of hypoeutectic Al–Si alloys, gray iron cylinder liners are required. These liners cause the development of large tensile residual stress along the cylinder bores and necessitate the maximization of mechanical properties in this region to prevent premature engine failure. The aim of this study was to replicate the engine cylinder bridge microstructure and mechanical properties following TSR treatment (which removes the sand binder to enable easy casting retrieval) using lab scale billet castings of the same alloy composition with varying cooling rates. Comparisons in microstructure between the engine block and the billet castings were carried out using optical and scanning electron microscopy, while mechanical properties were assessed using tensile testing. The results suggest that the microstructure at the top and middle of the engine block cylinder bridge was successfully replicated by the billet castings. However, the microstructure at the bottom of the cylinder was not completely replicated due to variations in secondary phase morphology and distribution. The successful replication of engine block microstructure will enable the future optimization of heat treatment parameters. - Highlights: • A method to replicate engine block microstructure was developed. • Billet castings will allow cost effective optimization of heat treatment process. • The replication of microstructure in the cylinder region was mostly successful. • Porosity was more clustered in the billet castings compared to the engine block. • Mechanical properties were lower in billet castings due to porosity and inclusions.

  12. Grain Boundary Engineering the Mechanical Properties of Allvac 718Plus(Trademark) Superalloy

    NASA Technical Reports Server (NTRS)

    Gabb, Timothy P.; Telesman, Jack; Garg, Anita; Lin, Peter; Provenzano, virgil; Heard, Robert; Miller, Herbert M.

    2010-01-01

    Grain Boundary Engineering can enhance the population of structurally-ordered "low S" Coincidence Site Lattice (CSL) grain boundaries in the microstructure. In some alloys, these "special" grain boundaries have been reported to improve overall resistance to corrosion, oxidation, and creep resistance. Such improvements could be quite beneficial for superalloys, especially in conditions which encourage damage and cracking at grain boundaries. Therefore, the effects of GBE processing on high-temperature mechanical properties of the cast and wrought superalloy Allvac 718Plus (Allvac ATI) were screened. Bar sections were subjected to varied GBE processing, and then consistently heat treated, machined, and tested at 650 C. Creep, tensile stress relaxation, and dwell fatigue crack growth tests were performed. The influences of GBE processing on microstructure, mechanical properties, and associated failure modes are discussed.

  13. Geoenvironmental and engineering properties of rock, soil, and aggregate. Transportation research record

    SciTech Connect

    Not Available

    1992-01-01

    Partial Contents: Use of Waste Materials in Highway Construction: State of the Practice and Evaluation of the Selected Waste Products; Physical and Environmental Properties of Asphalt-Amended Bottom Ash; Use of Cement Kiln Dust, Fly Ash, and Recycling Technique in Low-Volume Road Rehabilitation; Use of By-Product Phosphogypsum in Road Construction; Stabilization of Water Treatment Plant Sludge for Possible Use as Embankment Material; Construction and Performance of a Shredded Waste Tire Test Embankment; Corrosion of Steel Piles in Some Waste Fills; Recycled Plastics for Highway Agencies; Effect of Chloride and Sulfate Contamination in Soils on Corrosion of Steel and Concrete; Permeability and Leaching Characteristics of Fly Ash Liner Materials; Evaluation of Recycled Concrete, Open-Graded Aggregate, and Large Top-Size Aggregate Bases; Engineering Properties of Phosphogypsum-Based Slag Aggregate.

  14. Experiments and parametric studies on 3D metallic auxetic metamaterials with tuneable mechanical properties

    NASA Astrophysics Data System (ADS)

    Ren, Xin; Shen, Jianhu; Ghaedizadeh, Arash; Tian, Hongqi; Xie, Yi Min

    2015-09-01

    Auxetic metamaterials are synthetic materials with microstructures engineered to achieve negative Poisson’s ratios. Auxetic metamaterials are of great interest because of their unusual properties and various potential applications. However, most of the previous research has been focused on auxetic behaviour of elastomers under elastic deformation. Inspired by our recent finding of the loss of auxetic behaviour in metallic auxetic metamaterials, a systematic experimental and numerical investigation has been carried out to explore the mechanism behind this phenomenon. Using an improved methodology of generating buckling-induced auxetic metamaterials, several samples of metallic auxetic metamaterials have been fabricated using a 3D printing technique. The experiments on those samples have revealed the special features of auxetic behaviour for metallic auxetic metamaterials and proved the effectiveness of our structural modification. Parametric studies have been performed through experimentally validated finite element models to explore the auxetic performance of the designed metallic metamaterials. It is found that the auxetic performance can be tuned by the geometry of microstructures, and the strength and stiffness can be tuned by the plasticity of the base material while maintaining the auxetic performance.

  15. PGS:Gelatin Nanofibrous Scaffolds with Tunable Mechanical and Structural Properties for Engineering Cardiac Tissues

    PubMed Central

    Kharaziha, Mahshid; Nikkhah, Mehdi; Shin, Su-Ryon; Annabi, Nasim; Masoumi, Nafiseh; Gaharwar, Akhilesh K.; Camci-Unal, Gulden; Khademhosseini, Ali

    2013-01-01

    A significant challenge in cardiac tissue engineering is the development of biomimetic grafts that can potentially promote myocardial repair and regeneration. A number of approaches have used engineered scaffolds to mimic the architecture of the native myocardium tissue and precisely regulate cardiac cell functions. However previous attempts have not been able to simultaneously recapitulate chemical, mechanical, and structural properties of the myocardial extracellular matrix (ECM). In this study, we utilized an electrospinning approach to fabricate elastomeric biodegradable poly(glycerol-sebacate) (PGS):gelatin scaffolds with a wide range of chemical composition, stiffness and anisotropy. Our findings demonstrated that through incorporation of PGS, it is possible to create nanofibrous scaffolds with well-defined anisotropy that mimics the left ventricular myocardium architecture. Furthermore, we studied attachment, proliferation, differentiation and alignment of neonatal rat cardiac fibroblast cells (CFs) as well as protein expression, alignment, and contractile function of cardiomyocyte (CMs) on PGS:gelatin scaffolds with variable amount of PGS. Notably, aligned nanofibrous scaffold, consisting of 33 wt. % PGS, induced optimal synchronous contractions of CMs while significantly enhanced cellular alignment. Overall, our study suggests that the aligned nanofibrous PGS:gelatin scaffold support cardiac cell organization, phenotype and contraction and could potentially be used to develop clinically relevant constructs for cardiac tissue engineering. PMID:23747008

  16. PGS:Gelatin nanofibrous scaffolds with tunable mechanical and structural properties for engineering cardiac tissues.

    PubMed

    Kharaziha, Mahshid; Nikkhah, Mehdi; Shin, Su-Ryon; Annabi, Nasim; Masoumi, Nafiseh; Gaharwar, Akhilesh K; Camci-Unal, Gulden; Khademhosseini, Ali

    2013-09-01

    A significant challenge in cardiac tissue engineering is the development of biomimetic grafts that can potentially promote myocardial repair and regeneration. A number of approaches have used engineered scaffolds to mimic the architecture of the native myocardium tissue and precisely regulate cardiac cell functions. However, previous attempts have not been able to simultaneously recapitulate chemical, mechanical, and structural properties of the myocardial extracellular matrix (ECM). In this study, we utilized an electrospinning approach to fabricate elastomeric biodegradable poly(glycerol sebacate) (PGS):gelatin nanofibrous scaffolds with a wide range of chemical composition, stiffness and anisotropy. Our findings demonstrated that through incorporation of PGS, it is possible to create nanofibrous scaffolds with well-defined anisotropy that mimic the left ventricular myocardium architecture. Furthermore, we studied attachment, proliferation, differentiation and alignment of neonatal rat cardiac fibroblast cells (CFs) as well as protein expression, alignment, and contractile function of cardiomyocyte (CMs) on PGS:gelatin scaffolds with variable amount of PGS. Notably, aligned nanofibrous scaffold, consisting of 33 wt. % PGS, induced optimal synchronous contractions of CMs while significantly enhanced cellular alignment. Overall, our study suggests that the aligned nanofibrous PGS:gelatin scaffold support cardiac cell organization, phenotype and contraction and could potentially be used to develop clinically relevant constructs for cardiac tissue engineering.

  17. Looking beyond Lewis Structures: A General Chemistry Molecular Modeling Experiment Focusing on Physical Properties and Geometry

    ERIC Educational Resources Information Center

    Linenberger, Kimberly J.; Cole, Renee S.; Sarkar, Somnath

    2011-01-01

    We present a guided-inquiry experiment using Spartan Student Version, ready to be adapted and implemented into a general chemistry laboratory course. The experiment provides students an experience with Spartan Molecular Modeling software while discovering the relationships between the structure and properties of molecules. Topics discussed within…

  18. Dielectric Characteristics of Microstructural Changes and Property Evolution in Engineered Materials

    NASA Astrophysics Data System (ADS)

    Clifford, Jallisa Janet

    Heterogeneous materials are increasingly used in a wide range of applications such as aerospace, civil infrastructure, fuel cells and many others. The ability to take properties from two or more materials to create a material with properties engineered to needs is always very attractive. Hence heterogeneous materials are evolving into more complex formulations in multiple disciplines. Design of microstructure at multiple scales control the global functional properties of these materials and their structures. However, local microstructural changes do not directly cause a proportional change to the global properties (such as strength and stiffness). Instead, local changes follow an evolution process including significant interactions. Therefore, in order to understand property evolution of engineered materials, microstructural changes need to be effectively captured. Characterizing these changes and representing them by material variables will enable us to further improve our material level understanding. In this work, we will demonstrate how microstructural features of heterogeneous materials can be described quantitatively using broadband dielectric spectroscopy (BbDS). The frequency dependent dielectric properties can capture the change in material microstructure and represent these changes in terms of material variables, such as complex permittivity. These changes in terms of material properties can then be linked to a number of different conditions, such as increasing damage due to impact or fatigue. Two different broadband dielectric spectroscopy scanning modes are presented: bulk measurements and continuous scanning to measure dielectric property change as a function of position across the specimen. In this study, we will focus on ceramic materials and fiber reinforced polymer matrix composites as test bed material systems. In the first part of the thesis, we will present how different micro-structural design of porous ceramic materials can be captured

  19. Analytical and experimental evaluations of the effect of broad property fuels on combustors for commercial aircraft gas turbine engines

    NASA Technical Reports Server (NTRS)

    Smith, A. L.

    1980-01-01

    The impacts of broad property fuels on the design, performance, durability, emissions, and operational characteristics of current and advanced combustors for commercial aircraft gas turbine engines were studied. The effect of fuel thermal stability on engine and airframe fuel system was evaluated. Tradeoffs between fuel properties, exhaust emissions, and combustor life were also investigated. Results indicate major impacts of broad property fuels on allowable metal temperatures in fuel manifolds and injector support, combustor cyclic durability, and somewhat lesser impacts on starting characteristics, lightoff, emissions, and smoke.

  20. Engineered deafness reveals that mouse courtship vocalizations do not require auditory experience.

    PubMed

    Mahrt, Elena J; Perkel, David J; Tong, Ling; Rubel, Edwin W; Portfors, Christine V

    2013-03-27

    Auditory experience during development is necessary for normal language acquisition in humans. Although songbirds, some cetaceans, and maybe bats may also be vocal learners, vocal learning has yet to be well established for a laboratory mammal. Mice are potentially an excellent model organism for studying mechanisms underlying vocal communication. Mice vocalize in different social contexts, yet whether they learn their vocalizations remains unresolved. To address this question, we compared ultrasonic courtship vocalizations emitted by chronically deaf and normal hearing adult male mice. We deafened CBA/CaJ male mice, engineered to express diphtheria toxin (DT) receptors in hair cells, by systemic injection of DT at postnatal day 2 (P2). By P9, almost all inner hair cells were absent and by P16 all inner and outer hair cells were absent in DTR mice. These mice did not show any auditory brainstem responses as adults. Wild-type littermates, also treated with DT at P2, had normal hair cells and normal auditory brainstem responses. We compared the temporal structure of vocalization bouts, the types of vocalizations, the patterns of syllables, and the acoustic features of each syllable type emitted by hearing and deaf males in the presence of a female. We found that almost all of the vocalization features we examined were similar in hearing and deaf animals. These findings indicate that mice do not need auditory experience during development to produce normal ultrasonic vocalizations in adulthood. We conclude that mouse courtship vocalizations are not acquired through auditory feedback-dependent learning.

  1. 2-D Air-Breathing Lightcraft Engine Experiments in Hypersonic Conditions

    NASA Astrophysics Data System (ADS)

    Salvador, Israel I.; Myrabo, Leik N.; Minucci, Marco A. S.; de Oliveira, Antonio C.; Toro, Paulo G. P.; Chanes, José B.; Rego, Israel S.

    2011-11-01

    Experiments were performed with a 2-D, repetitively-pulsed (RP) laser Lightcraft model in hypersonic flow conditions. The main objective was the feasibility analysis for impulse generation with repetitively-pulsed air-breathing laser Lightcraft engines at hypersonic speeds. The future application of interest for this basic research endeavor is the laser launch of pico-, nano-, and micro-satellites (i.e., 0.1-100 kg payloads) into Low-Earth-Orbit, at low-cost and on-demand. The laser propulsion experiments employed a Hypersonic Shock Tunnel integrated with twin gigawatt pulsed Lumonics 620-TEA CO2 lasers (˜ 1 μs pulses), to produce the required test conditions. This hypersonic campaign was carried out at nominal Mach numbers ranging from 6 to 10. Time-dependent surface pressure distributions were recorded together with Schlieren movies of the flow field structure resulting from laser energy deposition. Results indicated laser-induced pressure increases of 0.7-0.9 bar with laser pulse energies of ˜ 170 J, on off-shroud induced breakdown condition, and Mach number of 7.

  2. Surface electrical properties experiment study phase, volume 3

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The reliability and quality assurance system and procedures used in developing test equipment for the Lunar Experiment projects are described. The subjects discussed include the following: (1) documentation control, (2) design review, (3) parts and materials selection, (4) material procurement, (5) inspection procedures, (6) qualification and special testing, and failure modes and effects analysis.

  3. Mathematical Modeling of Uniaxial Mechanical Properties of Collagen Gel Scaffolds for Vascular Tissue Engineering

    PubMed Central

    Irastorza, Ramiro M.; Drouin, Bernard; Blangino, Eugenia; Mantovani, Diego

    2015-01-01

    Small diameter tissue-engineered arteries improve their mechanical and functional properties when they are mechanically stimulated. Applying a suitable stress and/or strain with or without a cycle to the scaffolds and cells during the culturing process resides in our ability to generate a suitable mechanical model. Collagen gel is one of the most used scaffolds in vascular tissue engineering, mainly because it is the principal constituent of the extracellular matrix for vascular cells in human. The mechanical modeling of such a material is not a trivial task, mainly for its viscoelastic nature. Computational and experimental methods for developing a suitable model for collagen gels are of primary importance for the field. In this research, we focused on mechanical properties of collagen gels under unconfined compression. First, mechanical viscoelastic models are discussed and framed in the control system theory. Second, models are fitted using system identification. Several models are evaluated and two nonlinear models are proposed: Mooney-Rivlin inspired and Hammerstein models. The results suggest that Mooney-Rivlin and Hammerstein models succeed in describing the mechanical behavior of collagen gels for cyclic tests on scaffolds (with best fitting parameters 58.3% and 75.8%, resp.). When Akaike criterion is used, the best is the Mooney-Rivlin inspired model. PMID:25834840

  4. Mathematical modeling of uniaxial mechanical properties of collagen gel scaffolds for vascular tissue engineering.

    PubMed

    Irastorza, Ramiro M; Drouin, Bernard; Blangino, Eugenia; Mantovani, Diego

    2015-01-01

    Small diameter tissue-engineered arteries improve their mechanical and functional properties when they are mechanically stimulated. Applying a suitable stress and/or strain with or without a cycle to the scaffolds and cells during the culturing process resides in our ability to generate a suitable mechanical model. Collagen gel is one of the most used scaffolds in vascular tissue engineering, mainly because it is the principal constituent of the extracellular matrix for vascular cells in human. The mechanical modeling of such a material is not a trivial task, mainly for its viscoelastic nature. Computational and experimental methods for developing a suitable model for collagen gels are of primary importance for the field. In this research, we focused on mechanical properties of collagen gels under unconfined compression. First, mechanical viscoelastic models are discussed and framed in the control system theory. Second, models are fitted using system identification. Several models are evaluated and two nonlinear models are proposed: Mooney-Rivlin inspired and Hammerstein models. The results suggest that Mooney-Rivlin and Hammerstein models succeed in describing the mechanical behavior of collagen gels for cyclic tests on scaffolds (with best fitting parameters 58.3% and 75.8%, resp.). When Akaike criterion is used, the best is the Mooney-Rivlin inspired model.

  5. Detergent-enzymatic decellularization of swine blood vessels: insight on mechanical properties for vascular tissue engineering.

    PubMed

    Pellegata, Alessandro F; Asnaghi, M Adelaide; Stefani, Ilaria; Maestroni, Anna; Maestroni, Silvia; Dominioni, Tommaso; Zonta, Sandro; Zerbini, Gianpaolo; Mantero, Sara

    2013-01-01

    Small caliber vessels substitutes still remain an unmet clinical need; few autologous substitutes are available, while synthetic grafts show insufficient patency in the long term. Decellularization is the complete removal of all cellular and nuclear matters from a tissue while leaving a preserved extracellular matrix representing a promising tool for the generation of acellular scaffolds for tissue engineering, already used for various tissues with positive outcomes. The aim of this work is to investigate the effect of a detergent-enzymatic decellularization protocol on swine arteries in terms of cell removal, extracellular matrix preservation, and mechanical properties. Furthermore, the effect of storage at -80°C on the mechanical properties of the tissue is evaluated. Swine arteries were harvested, frozen, and decellularized; histological analysis revealed complete cell removal and preserved extracellular matrix. Furthermore, the residual DNA content in decellularized tissues was far low compared to native one. Mechanical testings were performed on native, defrozen, and decellularized tissues; no statistically significant differences were reported for Young's modulus, ultimate stress, compliance, burst pressure, and suture retention strength, while ultimate strain and stress relaxation of decellularized vessels were significantly different from the native ones. Considering the overall results, the process was confirmed to be suitable for the generation of acellular scaffolds for vascular tissue engineering.

  6. Manipulation of the mechanical properties of a virus by protein engineering

    PubMed Central

    Carrasco, Carolina; Castellanos, Milagros; de Pablo, Pedro J.; Mateu, Mauricio G.

    2008-01-01

    In a previous study, we showed that the DNA molecule within a spherical virus (the minute virus of mice) plays an architectural role by anisotropically increasing the mechanical stiffness of the virus. A finite element model predicted that this mechanical reinforcement is a consequence of the interaction between crystallographically visible, short DNA patches and the inner capsid wall. We have now tested this model by using protein engineering. Selected amino acid side chains have been truncated to specifically remove major interactions between the capsid and the visible DNA patches, and the effect of the mutations on the stiffness of virus particles has been measured using atomic force microscopy. The mutations do not affect the stiffness of the empty capsid; however, they significantly reduce the difference in stiffness between the DNA-filled virion and the empty capsid. The results (i) reveal that intermolecular interactions between individual chemical groups contribute to the mechanical properties of a supramolecular assembly and (ii) identify specific protein–DNA interactions as the origin of the anisotropic increase in the rigidity of a virus. This study also demonstrates that it is possible to control the mechanical properties of a protein nanoparticle by the rational application of protein engineering based on a mechanical model. PMID:18334651

  7. Detergent-Enzymatic Decellularization of Swine Blood Vessels: Insight on Mechanical Properties for Vascular Tissue Engineering

    PubMed Central

    Pellegata, Alessandro F.; Asnaghi, M. Adelaide; Stefani, Ilaria; Maestroni, Anna; Maestroni, Silvia; Dominioni, Tommaso; Zonta, Sandro; Zerbini, Gianpaolo; Mantero, Sara

    2013-01-01

    Small caliber vessels substitutes still remain an unmet clinical need; few autologous substitutes are available, while synthetic grafts show insufficient patency in the long term. Decellularization is the complete removal of all cellular and nuclear matters from a tissue while leaving a preserved extracellular matrix representing a promising tool for the generation of acellular scaffolds for tissue engineering, already used for various tissues with positive outcomes. The aim of this work is to investigate the effect of a detergent-enzymatic decellularization protocol on swine arteries in terms of cell removal, extracellular matrix preservation, and mechanical properties. Furthermore, the effect of storage at −80°C on the mechanical properties of the tissue is evaluated. Swine arteries were harvested, frozen, and decellularized; histological analysis revealed complete cell removal and preserved extracellular matrix. Furthermore, the residual DNA content in decellularized tissues was far low compared to native one. Mechanical testings were performed on native, defrozen, and decellularized tissues; no statistically significant differences were reported for Young's modulus, ultimate stress, compliance, burst pressure, and suture retention strength, while ultimate strain and stress relaxation of decellularized vessels were significantly different from the native ones. Considering the overall results, the process was confirmed to be suitable for the generation of acellular scaffolds for vascular tissue engineering. PMID:23865072

  8. Effect of variety and moisture content on some engineering properties of paddy rice.

    PubMed

    Adebowale, Abdul-Rasaq A; Sanni, Lateef O; Owo, Hameed O; Karim, Olayinka R

    2011-10-01

    The effect of variety and moisture content on some engineering properties of five improved paddy rice varieties was investigated within moisture content range of 10% and 30% dry basis (d.b.). Increase in moisture content was found to increase the linear dimensions, mass of 100 seeds, surface area, apparent volume, true volume, arithmetic mean diameter, effective geometric diameter, sphericity, angle of repose, porosity and static coefficient of friction while bulk density and true density decreased with increase in moisture content. Static coefficient of friction was found to increase as moisture content increased from 0.34-0.46, 0.35-0.59, 0.36-0.46 and 0.34-0.45, respectively on plywood, galvanized steel, mild steel and glass structural surfaces. The highest static coefficient was found on galvanized steel. Angle of repose was found to increase as moisture content increases. The study concludes that variety and changes in moisture content significantly (P < 0.05) affected most of the engineering properties determined.

  9. Optical properties of CdSe nanowires -- Experiment and theory

    NASA Astrophysics Data System (ADS)

    Vietmeyer, Felix

    CdSe nanowires are one-dimensional semiconductor nanostructures with unique properties. The wires studied in this work possess diameters on the nanometer scale while diameters are on the order of tens of microns. For CdSe structures this has the consequence that size quantization effects are at play along the radial dimension while longitudinal dimensions are outside the confinement regime. Physical and electrical properties are therefore expected to be diameter dependent, but not very sensitive to variations in length. Another important aspect to consider is that the diameters studied span a range from small (i.e. d˜3-5 nm) where wires show discrete transitions akin to quantum dots all the way up to large (i.e. d˜25 nm). At the largest size studied, the material does not show size quantization effects and its properties are similar to bulk CdSe. One of the key questions I would like to answer is what characterizes the transition from a regime controlled by quantum effects (i.e. small diameter nanowires) to bulk-like semiconductors (i.e. large diameter wires). The tools used to carry out the characterization include a number of steady-state and time-resolved spectroscopic techniques that are used to probe semiconductor nanowires both on the ensemble and single nanowire level. For single wire level measurements, the tool of choice is optical microscopy. Using microscopy, individual nanowires can be identified and studied using various excitation and emission wavelengths to characterize their properties. Using emission and absorption spectroscopies, the electronic structure of the nanowire as well as how charges interact is revealed. It, in turn, allows identifying signatures that belong to photogenerated charges that exist as coulombically bound electron-hole pairs (excitons) and distinguish them from free charges.

  10. Surface modification and property analysis of biomedical polymers used for tissue engineering.

    PubMed

    Ma, Zuwei; Mao, Zhengwei; Gao, Changyou

    2007-11-15

    The response of host organism in macroscopic, cellular and protein levels to biomaterials is, in most cases, closely associated with the materials' surface properties. In tissue engineering, regenerative medicine and many other biomedical fields, surface engineering of the bio-inert synthetic polymers is often required to introduce bioactive species that can promote cell adhesion, proliferation, viability and enhanced ECM-secretion functions. Up to present, a large number of surface engineering techniques for improving biocompatibility have been well established, the work of which generally contains three main steps: (1) surface modification of the polymeric materials; (2) chemical and physical characterizations; and (3) biocompatibility assessment through cell culture. This review focuses on the principles and practices of surface engineering of biomedical polymers with regards to particular aspects depending on the authors' research background and opinions. The review starts with an introduction of principles in designing polymeric biomaterial surfaces, followed by introduction of surface modification techniques to improve hydrophilicity, to introduce reactive functional groups and to immobilize functional protein molecules. The chemical and physical characterizations of the modified biomaterials are then discussed with emphasis on several important issues such as surface functional group density, functional layer thickness, protein surface density and bioactivity. Three most commonly used surface composition characterization techniques, i.e. ATR-FTIR, XPS, SIMS, are compared in terms of their penetration depth. Ellipsometry, CD, EPR, SPR and QCM's principles and applications in analyzing surface proteins are introduced. Finally discussed are frequently applied methods and their principles to evaluate biocompatibility of biomaterials via cell culture. In this section, current techniques and their developments to measure cell adhesion, proliferation, morphology

  11. Nanohydroxyapatite Effect on the Degradation, Osteoconduction and Mechanical Properties of Polymeric Bone Tissue Engineered Scaffolds

    PubMed Central

    Salmasi, Shima; Nayyer, Leila; Seifalian, Alexander M.; Blunn, Gordon W.

    2016-01-01

    BACKGROUND Statistical reports show that every year around the world approximately 15 million bone fractures occur; of which up to 10% fail to heal completely and hence lead to complications of non-union healing. In the past, autografts or allografts were used as the “gold standard” of treating such defects. However, due to various limitations and risks associated with these sources of bone grafts, other avenues have been extensively investigated through which bone tissue engineering; in particular engineering of synthetic bone graft substitutes, has been recognised as a promising alternative to the traditional methods. METHODS A selective literature search was performed. RESULTS Bone tissue engineering offers unlimited supply, eliminated risk of disease transmission and relatively low cost. It could also lead to patient specific design and manufacture of implants, prosthesis and bone related devices. A potentially promising building block for a suitable scaffold is synthetic nanohydroxyapatite incorporated into synthetic polymers. Incorporation of nanohydroxyapatite into synthetic polymers has shown promising bioactivity, osteoconductivity, mechanical properties and degradation profile compared to other techniques previously considered. CONCLUSION Scientific research, through extensive physiochemical characterisation, in vitro and in vivo assessment has brought together the optimum characteristics of nanohydroxyapatite and various types of synthetic polymers in order to develop nanocomposites of suitable nature for bone tissue engineering. The aim of the present article is to review and update various aspects involved in incorporation of synthetic nanohydroxyapatite into synthetic polymers, in terms of their potentials to promote bone growth and regeneration in vitro, in vivo and consequently in clinical applications. PMID:28217213

  12. Ecological Engineering Approaches to Improve Hydraulic Properties of Infiltration Basins Designed for Groundwater Recharge.

    PubMed

    Gette-Bouvarot, Morgane; Volatier, Laurence; Lassabatere, Laurent; Lemoine, Damien; Simon, Laurent; Delolme, Cécile; Mermillod-Blondin, Florian

    2015-08-18

    Infiltration systems are increasingly used in urban areas for groundwater recharge. The reduction of sediment permeability by physical and/or biological processes is a major problem in management of infiltration systems often requiring expensive engineering operations for hydraulic performance maintenance. To reduce these costs and for the sake of sustainable development, we proposed to evaluate the ability of ecological engineering approaches to reduce the biological clogging of infiltration basins. A 36-day field-scale experiment using enclosures was performed to test the influences of abiotic (light reduction by shading) and biotic (introduction of the macrophyte Vallisneria spiralis (L.) or the gastropod Viviparus viviparus (Linnaeus, 1758)) treatments to limit benthic biofilm biomass and to maintain or even increase hydraulic performances. We coupled biological characterization of sediment (algal biomass, bacterial abundance, total organic carbon, total nitrogen, microbial enzymatic activity, photosynthetic activity, and photosystem II efficiency) with hydraulic conductivity measurements to assess the effects of treatments on sediment permeability. The grazer Viviparus viviparus significantly reduced benthic biofilm biomass and enhanced hydraulic conductivity. The other treatments did not produce significant changes in hydraulic conductivity although Vallisneria spiralis affected photosynthetic activity of biofilm. Finally, our results obtained with Viviparus viviparus are promising for the development of ecological engineering solutions to prevent biological fouling in infiltration systems.

  13. Reverse engineering nuclear properties from rare earth abundances in the r process

    NASA Astrophysics Data System (ADS)

    Mumpower, M. R.; McLaughlin, G. C.; Surman, R.; Steiner, A. W.

    2017-03-01

    The bulk of the rare earth elements are believed to be synthesized in the rapid neutron capture process or r process of nucleosynthesis. The solar r-process residuals show a small peak in the rare earths around A∼ 160, which is proposed to be formed dynamically during the end phase of the r process by a pileup of material. This abundance feature is of particular importance as it is sensitive to both the nuclear physics inputs and the astrophysical conditions of the main r process. We explore the formation of the rare earth peak from the perspective of an inverse problem, using Monte Carlo studies of nuclear masses to investigate the unknown nuclear properties required to best match rare earth abundance sector of the solar isotopic residuals. When nuclear masses are changed, we recalculate the relevant β-decay properties and neutron capture rates in the rare earth region. The feedback provided by this observational constraint allows for the reverse engineering of nuclear properties far from stability where no experimental information exists. We investigate a range of astrophysical conditions with this method and show how these lead to different predictions in the nuclear properties influential to the formation of the rare earth peak. We conclude that targeted experimental campaigns in this region will help to resolve the type of conditions responsible for the production of the rare earth nuclei, and will provide new insights into the longstanding problem of the astrophysical site(s) of the r process.

  14. Reversible Tuning of Individual Carbon Nanotube Mechanical Properties via Defect Engineering.

    PubMed

    Zhang, Bin; Zhao, Longze; Cheng, Yong; Golberg, Dmitri; Wang, Ming-Sheng

    2016-08-10

    The structural defects that inevitably exist in real-world carbon nanotubes (CNTs) are generally considered undesirable because they break the structural perfection and may result in drastically degraded CNT properties. On the other hand, the deliberate defect introduction can provide a possibility to tailor the tube mechanical properties. Herein, we present a fully controllable technique to handle defects by using in situ transmission electron microscopy (TEM). Young's modulus, quality factor of the resonation and tensile strength of CNTs can be controllably, reversibly, and repeatedly tuned. Parallel high-resolution visualizing of structural defects suggests that the property tuning cycles are primarily attributed to the reversible conversion of defects at the atomic scale: the defects are created in the form of vacancies and interstitials under electron irradiation, and they vanish through the recombination via current-induced annealing. For applications, such as reversible frequency-tuned CNT resonators, this defect-engineering technique is demonstrated to be uniquely precise; the frequency may be tuned with 0.1%/min accuracy, improved by 1 order of magnitude compared with the existing approaches. We believe that these results will be highly valuable in a variety of property-tunable CNT-based composites and devices.

  15. Mechanical properties of native and tissue-engineered cartilage depend on carrier permeability: a bioreactor study.

    PubMed

    Hoenig, Elisa; Leicht, Uta; Winkler, Thomas; Mielke, Gabriela; Beck, Katharina; Peters, Fabian; Schilling, Arndt F; Morlock, Michael M

    2013-07-01

    The implantation of osteochondral constructs-tissue-engineered (TE) cartilage on a bone substitute carrier-is a promising method to treat defects in articular cartilage. Currently, however, the TE cartilage's mechanical properties are clearly inferior to those of native cartilage. Their improvement has been the subject of various studies, mainly focusing on growth factors and physical loading during cultivation. With the approach of osteochondral constructs another aspect arises: the permeability of the carrier materials. The purpose of this study was to investigate whether and how the permeability of the subchondral bone influences the properties of native cartilage and whether the bone substitute carrier's permeability influences the TE cartilage of osteochondral constructs accordingly. Consequently, the influence of the subchondral bone's permeability on native cartilage was determined: Native porcine cartilage-bone cylinders were cultivated for 2 weeks in a bioreactor under mechanical loading with and without restricted permeability of the bone. For the TE cartilage these two permeability conditions were investigated using permeable and impermeable tricalciumphosphate carriers under equivalent cultivation conditions. All specimens were evaluated mechanically, biochemically, and histologically. The restriction of the bone's permeability significantly decreased the Young's modulus of native cartilage in vitro. No biochemical differences were found. This finding was confirmed for TE cartilage: While the biochemical parameters were not affected, a permeable carrier improved the cell morphology and mechanical properties in comparison to an impermeable one. In conclusion, the carrier permeability was identified as a determining factor for the mechanical properties of TE cartilage of osteochondral constructs.

  16. Long-term stability and properties of zirconia ceramics for heavy duty diesel engine components

    NASA Technical Reports Server (NTRS)

    Larsen, D. C.; Adams, J. W.

    1985-01-01

    Physical, mechanical, and thermal properties of commercially available transformation-toughened zirconia are measured. Behavior is related to the material microstructure and phase assemblage. The stability of the materials is assessed after long-term exposure appropriate for diesel engine application. Properties measured included flexure strength, elastic modulus, fracture toughness, creep, thermal shock, thermal expansion, internal friction, and thermal diffusivity. Stability is assessed by measuring the residual property after 1000 hr/1000C static exposure. Additionally static fatigue and thermal fatigue testing is performed. Both yttria-stabilized and magnesia-stabilized materials are compared and contrasted. The major limitations of these materials are short term loss of properties with increasing temperature as the metastable tetragonal phase becomes more stable. Fine grain yttria-stabilized material (TZP) is higher strength and has a more stable microstructure with respect to overaging phenomena. The long-term limitation of Y-TZP is excessive creep deformation. Magnesia-stabilized PSZ has relatively poor stability at elevated temperature. Overaging, decomposition, and/or destabilization effects are observed. The major limitation of Mg-PSZ is controlling unwanted phase changes at elevated temperature.

  17. Additive Manufacturing, Design, Testing, and Fabrication: A Full Engineering Experience at JSC

    NASA Technical Reports Server (NTRS)

    Zusack, Steven

    2016-01-01

    I worked on several projects this term. While most projects involved additive manufacturing, I was also involved with two design projects, two testing projects, and a fabrication project. The primary mentor for these was Richard Hagen. Secondary mentors were Hai Nguyen, Khadijah Shariff, and fabrication training from James Brown. Overall, my experience at JSC has been successful and what I have learned will continue to help me in my engineering education and profession long after I leave. My 3D printing projects ranged from less than a 1 cubic centimeter to about 1 cubic foot and involved several printers using different printing technologies. It was exciting to become familiar with printing technologies such as industrial grade FDM (Fused Deposition Modeling), the relatively new SLA (Stereolithography), and PolyJet. My primary duty with the FDM printers was to model parts that came in from various sources to print effectively and efficiently. Using methods my mentor taught me and the Stratasys Insight software, I was able to minimize imperfections, hasten build time, improve strength for specific forces (tensile, shear, etc...), and reduce likelihood of a print-failure. Also using FDM, I learned how to repair a part after it was printed. This is done by using a special kind of glue that chemically melts the two faces of plastic parts together to form a fused interface. My first goal with SLA technology was to bring the printer back to operational readiness. In becoming familiar with the Pegasus SLA printer, I researched the leveling, laser settings, and different vats to hold liquid material. With this research, I was successfully able to bring the Pegasus back online and have successfully printed multiple sample parts as well as functional parts. My experience with PolyJet technology has been focused on an understanding of the abilities/limits, costs, and the maintenance for daily use. Still upcoming will be experience with using a composite printer that uses FDM

  18. Experiences of African American Young Women in Science, Technology, Engineering, and Mathematics (STEM) Education

    NASA Astrophysics Data System (ADS)

    Kolo, Yovonda Ingram

    African American women are underrepresented in science, technology, engineering, and mathematics (STEM) fields throughout the United States. As the need for STEM professionals in the United States increases, it is important to ensure that African American women are among those professionals making valuable contributions to society. The purpose of this phenomenological study was to describe the experiences of African American young women in relation to STEM education. The research question for this study examined how experiences with STEM in K-10 education influenced African American young women's academic choices in their final years in high school. The theory of multicontextuality was used to provide the conceptual framework. The primary data source was interviews. The sample was composed of 11 African American young women in their junior or senior year in high school. Data were analyzed through the process of open coding, categorizing, and identifying emerging themes. Ten themes emerged from the answers to research questions. The themes were (a) high teacher expectations, (b) participation in extra-curricular activities, (c) engagement in group-work, (d) learning from lectures, (e) strong parental involvement, (f) helping others, (g) self-efficacy, (h) gender empowerment, (i) race empowerment, and (j) strategic recruitment practices. This study may lead to positive social change by adding to the understanding of the experiences of African American young women in STEM. By doing so, these findings might motivate other African American young women to pursue advanced STEM classes. These findings may also provide guidance to parents and educators to help increase the number of African American women in STEM.

  19. GIGABAR MATERIAL PROPERTIES EXPERIMENTS ON NIF AND OMEGA

    SciTech Connect

    Swift, D C; Hawreliak, J A; Braun, D; Kritcher, A; Glenzer, S; Collins, G W; Rothman, S D; Chapman, D; Rose, S

    2011-08-04

    The unprecedented laser capabilities of the National Ignition Facility (NIF) make it possible for the first time to countenance laboratory-scale experiments in which gigabar pressures can be applied to a reasonable volume of material, and sustained long enough for percent level equation of state measurements to be made. We describe the design for planned experiments at the NIF, using a hohlraum drive to induce a spherically-converging shock in samples of different materials. Convergence effects increase the shock pressure to several gigabars over a radius of over 100 microns. The shock speed and compression will be measured radiographically over a range of pressures using an x-ray streak camera. In some cases, we will use doped layers to allow a radiographic measurement of particle velocity.

  20. Project Based Learning experiences in the space engineering education at Technical University of Madrid

    NASA Astrophysics Data System (ADS)

    Rodríguez, Jacobo; Laverón-Simavilla, Ana; del Cura, Juan M.; Ezquerro, José M.; Lapuerta, Victoria; Cordero-Gracia, Marta

    2015-10-01

    This work describes the innovation activities performed in the field of space education since the academic year 2009/10 at the Technical University of Madrid (UPM), in collaboration with the Spanish User Support and Operations Center (E-USOC), the center assigned by the European Space Agency (ESA) in Spain to support the operations of scientific experiments on board the International Space Station. These activities have been integrated within the last year of the UPM Aerospace Engineering degree. A laboratory has been created, where students have to validate and integrate the subsystems of a microsatellite using demonstrator satellites. In parallel, the students participate in a Project Based Learning (PBL) training process in which they work in groups to develop the conceptual design of a space mission. One student in each group takes the role of project manager, another one is responsible for the mission design and the rest are each responsible for the design of one of the satellite subsystems. A ground station has also been set up with the help of students developing their final thesis, which will allow future students to perform training sessions and learn how to communicate with satellites, how to receive telemetry and how to process the data. Several surveys have been conducted along two academic years to evaluate the impact of these techniques in engineering learning. The surveys evaluate the acquisition of specific and generic competences, as well as the students' degree of satisfaction with respect to the use of these learning methodologies. The results of the surveys and the perception of the lecturers show that PBL encourages students' motivation and improves their results. They not only acquire better technical training, but also improve their transversal skills. It is also pointed out that this methodology requires more dedication from lecturers than traditional methods.

  1. A new experience: the course of ethics in engineering in the Department of Civil Engineering, University of Granada.

    PubMed

    Gil-Martín, Luisa María; Hernández-Montes, Enrique; Segura-Naya, Armando

    2010-06-01

    A course in professional ethics for civil engineers was taught for the first time in Spain during the academic year 2007/08. In this paper a survey on the satisfaction and expectation of the course is presented. Surprisingly the students sought moral and ethical principles for their own ordinary lives as well as for their profession. Students were concerned about the law, but in their actions they were more concerned with their conscience, aware that it can be separate from the law.

  2. Creating a Bridge to Simulate Simultaneous Engineering Experiences for Senior Undergraduate Students

    ERIC Educational Resources Information Center

    Otieno, Andrew; Azad, Abul; Balamuralikrishna, Radha

    2006-01-01

    Launching new or improved products to the market typically involves extensive collaboration within and beyond the enterprise. Succeeding in a customer-driven market economy demands the practice of simultaneous engineering. The standard engineering or engineering technology curricula continue to make efforts in providing students with opportunities…

  3. Entrepreneurship in the Engineering Curriculum: Some Initial Results of PUC-Rio's Experiment.

    ERIC Educational Resources Information Center

    Aranha, Jose Alberto S.; Pimenta-Bueno, J. A.; Scavarda do Carmo, Luiz Carlos; da Silveira, Marcos A.

    The ideal of the entrepreneurial spirit has played a key role in shaping the current reform of engineering education at the Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio). The previous paradigm of a science-based conceptual engineer has given place to what may be termed a science-based entrepreneurial engineer. This paper discusses…

  4. Preparing University Students to Lead K-12 Engineering Outreach Programmes: A Design Experiment

    ERIC Educational Resources Information Center

    Anthony, Anika B.; Greene, Howard; Post, Paul E.; Parkhurst, Andrew; Zhan, Xi

    2016-01-01

    This paper describes an engineering outreach programme designed to increase the interest of under-represented youth in engineering and to disseminate pre-engineering design challenge materials to K-12 educators and volunteers. Given university students' critical role as facilitators of the outreach programme, researchers conducted a two-year…

  5. Building a Framework for Engineering Design Experiences in STEM: A Synthesis

    ERIC Educational Resources Information Center

    Denson, Cameron D.

    2011-01-01

    Since the inception of the National Center for Engineering and Technology Education in 2004, educators and researchers have struggled to identify the necessary components of a "good" engineering design challenge for high school students. In reading and analyzing the position papers on engineering design many themes emerged that may begin to form a…

  6. The Characteristics and Experiences of Successful Undergraduate Latina Students Who Persist in Engineering

    ERIC Educational Resources Information Center

    Robinson, Carrie

    2012-01-01

    Females and underrepresented ethnic minorities earn a small percentage of engineering and computer science bachelor's degrees awarded in the United States, earn an even smaller proportion of master's and doctoral degrees, and are underrepresented in the engineering workforce (Engineering Workforce Commission, [2006], as cited in National Science…

  7. Remote Sensing of Spectral Aerosol Properties: A Classroom Experience

    NASA Technical Reports Server (NTRS)

    Levy, Robert C.; Pinker, Rachel T.

    2006-01-01

    Bridging the gap between current research and the classroom is a major challenge to today s instructor, especially in the sciences where progress happens quickly. NASA Goddard Space Flight Center and the University of Maryland teamed up in designing a graduate class project intended to provide a hands-on introduction to the physical basis for the retrieval of aerosol properties from state-of-the-art MODIS observations. Students learned to recognize spectral signatures of atmospheric aerosols and to perform spectral inversions. They became acquainted with the operational MODIS aerosol retrieval algorithm over oceans, and methods for its evaluation, including comparisons with groundbased AERONET sun-photometer data.

  8. Martian physical properties experiments: The Viking Mars Lander

    USGS Publications Warehouse

    Shorthill, R.W.; Hutton, R.E.; Moore, H.J.; Scott, R.F.

    1972-01-01

    Current data indicate that Mars, like the Earth and Moon, will have a soil-like layer. An understanding of this soil-like layer is an essential ingredient in understanding the Martian ecology. The Viking Lander and its subsystems will be used in a manner similar to that used by Sue Surveyor program to define properties of the Martian "soil". Data for estimates of bearing strength, cohesion, angle of internal friction, porosity, grain size, adhesion, thermal inertia, dielectric constants, and homogeneity of the Martian surface materials will be collected. ?? 1972.

  9. Investigation on mechanical properties of basalt composite fabrics (experiment study)

    NASA Astrophysics Data System (ADS)

    Talebi Mazraehshahi, H.; Zamani, H.

    2010-06-01

    To fully appreciate the role and application of composite materials to structures, correct understanding of mechanical behaviors required for selection of optimum material. Fabric reinforced composites are composed of a matrix that is reinforced with pliable fabric, glass fabric is most popular reinforcement for different application specially in aircraft structure, although other fabric material are also used. At this study new fabric material called basalt with epoxy resin introduced and mechanical behaviors of this material investigated from view point of testing. For this study two type of fabric with different thickness used. Comparison between this composite reinforcement with popular reinforcement as carbon, glass, kevlar performed. To determine mechanical properties of epoxy based basalt fabric following test procedure performed : 1). Tensile testing according to ASTM D3039 in 0° and 90° direction to find ultimate strength in tension and shear, modulus of elasticity, elangation and ultimate strain. 2). Compression testing according to EN 2850 ultimate compression strength and maximum deformation under compression loading. 3). Shear testing according to ASTM D3518-94 to find in plane shear response of polymer matrix composites materials. 4). Predict flexural properties of sandwich construction which manufactured from basalt facing with PVC foam core according to ASTM C393-94. Material strength properties must be based on enough tests of material to meet the test procedure specifications [1]. For this reason six specimens were manufactured for testing and the tests were performed on them using an INSTRON machine model 5582. In the study, the effect of percent of resin in basalt reinforced composite was investigated. Also the weights of the ballast based composites with different percent of resin were measured with conventional composites. As the weight is an important parameter in aerospace industry when the designer wants to replace one material with

  10. Internalisation of engineered nanoparticles into mammalian cells in vitro: influence of cell type and particle properties

    NASA Astrophysics Data System (ADS)

    Busch, Wibke; Bastian, Susanne; Trahorsch, Ulrike; Iwe, Maria; Kühnel, Dana; Meißner, Tobias; Springer, Armin; Gelinsky, Michael; Richter, Volkmar; Ikonomidou, Chrysanthy; Potthoff, Annegret; Lehmann, Irina; Schirmer, Kristin

    2011-01-01

    Cellular internalisation of industrial engineered nanoparticles is undesired and a reason for concern. Here we investigated and compared the ability of seven different mammalian cell cultures in vitro to incorporate six kinds of engineered nanoparticles, focussing on the role of cell type and particle properties in particle uptake. Uptake was examined using light and electron microscopy coupled with energy dispersive X-ray spectroscopy (EDX) for particle element identification. Flow cytometry was applied for semi-quantitative analyses of particle uptake and for exploring the influence on uptake by the phagocytosis inhibitor Cytochalasin D (CytoD). All particles studied were found to enter each kind of cultured cells. Yet, particles were never found within cell nuclei. The presence of the respective particles within the cells was confirmed by EDX. Live-cell imaging revealed the time-dependent process of internalisation of technical nanoparticles, which was exemplified by tungsten carbide particle uptake into the human skin cells, HaCaT. Particles were found to co-localise with lysosomal structures within the cells. The incorporated nanoparticles changed the cellular granularity, as measured by flow cytometry, already after 3 h of exposure in a particle specific manner. By correlating particle properties with flow cytometry data, only the primary particle size was found to be a weakly influential property for particle uptake. CytoD, an inhibitor of actin filaments and therewith of phagocytosis, significantly inhibited the internalisation of particle uptake in only two of the seven investigated cell cultures. Our study, therefore, supports the notion that nanoparticles can enter mammalian cells quickly and easily, irrespective of the phagocytic ability of the cells.

  11. Performance mapping of the STM4-120 kinematic Stirling engine using a statistical design of experiments method

    NASA Astrophysics Data System (ADS)

    Powell, M. A.; Rawlinson, K. S.

    A kinetic Stirling cycle engine, the Stirling Thermal Motors (STM) STM4-120, was tested at the Sandia National Laboratories Engine Test Facility (ETF) from March 1989-August 1992. Sandia is interested in determining this engine's potential for solar-thermal-electric applications. The last round of testing was conducted from July-August 1992 using Sandia-designed gas-fired heat pipe evaporators as the heat input system to the engine. The STM4-120 was performance mapped over a range of sodium vapor temperatures, cooling water temperatures, and cycle pressures. The resulting shaft power output levels ranged from 5-9 kW. The engine demonstrated high conversion efficiency (24-31%) even though the power output level was less than 40% of the rated output of 25 kW. The engine had been previously derated from 25 kW to 10 kW shaft power due to mechanical limitations that were identified by STM during parallel testing at their facility in Ann Arbor, MI. A statistical method was used to design the experiment, to choose the experimental points, and to generate correlation equations describing the engine performance given the operating parameters. The testing was truncated due to a failure of the heat pipe system caused by entrainment of liquid sodium in the condenser section of the heat pipes. Enough data was gathered to generate the correlations and to demonstrate the experimental technique. The correlation is accurate in the experimental space and is simple enough for use in hand calculations and spreadsheet-based system models. Use of this method can simplify the construction of accurate performance and economic models of systems in which the engine is a component. The purpose of this paper is to present the method used to design the experiments and to analyze the performance data.

  12. Designing and Creating a Set of New Lab Experiments for a Traditional Fluid Mechanics Course in Civil Engineering

    NASA Astrophysics Data System (ADS)

    Budny, Dan

    2013-11-01

    Many fluids lab facilities and their associated student experiences were built back in the 1960-1970 time frames. They typically consisted of large facilities that included wind tunnels, flumes, wet wells, pump stations, etc. Today these labs are physically and pedagogically out dated and the need for lab space is forcing the closing of large scale labs. This is the same basic problem within the Swanson School of Engineering at the University of Pittsburgh. Thus we have replaced all the old equipment and lab experiences with small bench top experiments with a focus on applying the large body of knowledge associate with better student learning experiences. This paper will describe the concepts behind the design of the new experiments and the learning improvements discovered as a result of moving from a few large experiments to a larger number of smaller scale experiments.

  13. FTIR Determination of Pollutants in Automobile Exhaust: An Environmental Chemistry Experiment Comparing Cold-Start and Warm-Engine Conditions

    ERIC Educational Resources Information Center

    Medhurst, Laura L.

    2005-01-01

    An experiment developed from the Advanced Integrated Environmental Laboratory illustrates the differences in automobile exhaust before and after the engine is warmed, using gas-phase Fourier transform infrared spectroscopy (FTIR). The apparatus consists of an Avatar 360 FTIR spectrometer from Nicolet fitted with a variable path length gas cell,…

  14. Relating Engineering Technology Students' Experiences in Electromagnetics with Performance in Communications Coursework: A Mixed-Methods Study

    ERIC Educational Resources Information Center

    Richards, Grant P.

    2009-01-01

    This study presents the results of a multi-year mixed-methods study of students' performance (n = 94) and experiences (n = 28) with electromagnetics in an elective Electrical and Computer Engineering Technology RF communications course. Data sources used in this study include academic transcripts, course exams, interviews, a learning styles…

  15. Interdisciplinary Team-Teaching Experience for a Computer and Nuclear Energy Course for Electrical and Computer Engineering Students

    ERIC Educational Resources Information Center

    Kim, Charles; Jackson, Deborah; Keiller, Peter

    2016-01-01

    A new, interdisciplinary, team-taught course has been designed to educate students in Electrical and Computer Engineering (ECE) so that they can respond to global and urgent issues concerning computer control systems in nuclear power plants. This paper discusses our experience and assessment of the interdisciplinary computer and nuclear energy…

  16. Engaging Women in Computer Science and Engineering: Promising Practices for Promoting Gender Equity in Undergraduate Research Experiences

    ERIC Educational Resources Information Center

    Kim, Karen A.; Fann, Amy J.; Misa-Escalante, Kimberly O.

    2011-01-01

    Building on research that identifies and addresses issues of women's underrepresentation in computing, this article describes promising practices in undergraduate research experiences that promote women's long-term interest in computer science and engineering. Specifically, this article explores whether and how REU programs include programmatic…

  17. Innovations To Improve Teaching Quality at Escola Politecnica of USP: Experience at Metallurgical and Materials Engineering Department.

    ERIC Educational Resources Information Center

    Brandi, Sergio Duarte; Masseto, Marcos

    The experience described in this work was conducted in a discipline at Escola Politecnica in University of Sao Paulo. This discipline has a multidisciplinary character and almost all subjects discussed during engineering course might be addressed. Also, aspects related to aptitude and attitudes can be easily trained and discussed in this…

  18. Synthetically engineered chitosan-based materials and their sorption properties with methylene blue in aqueous solution.

    PubMed

    Guo, Rui; Wilson, Lee D

    2012-12-15

    Chitosan (CS) and poly(acrylic acid) (PAA) were crosslinked by an ionic gelation method to form super absorbent polymers (SAPs). CS and PAA form amide bonds between the amino and carboxyl groups. The CS-PAA copolymers were synthetically engineered by varying the feed ratios of the prepolymer units. The copolymer materials possess tunable sorption and mucoadhesive properties with a backbone structure resembling proteinaceous materials. The sorption properties of the copolymers toward methylene blue (MB) in aqueous solution were studied using UV-Vis spectrophotometry at ambient pH and 295 K. The copolymers showed markedly varied interactions with MB, from physisorption- to chemisorption-like behavior, in accordance with their composition, surface area, and pore structure characteristics. The sorption isotherms were evaluated with the Sips model to provide estimates of the sorption properties. The sorbent surface area (271 and 943 m(2)/g) and the sorption capacity (Q(m)=1.03 and 3.59 mmol/g) were estimated for the CS-PAA copolymer/MB systems in aqueous solution.

  19. Small Particles - Big Change? Engineered Nanomaterial Effects on Soil Subsurface Properties

    NASA Astrophysics Data System (ADS)

    Dror, I.; Yaron, B.; Berkowitz, B.

    2014-12-01

    A large number of research papers on the fate of engineered nanomaterials (ENMs) in the soil-water system have appeared in recent years, focusing on ENM transport, persistence and toxicological impact. However, very few studies have examined the impact of ENMs on the natural soil-subsurface matrix and its properties. Potential irreversible changes to natural soil-subsurface systems that originate from contact with other chemical contaminants of anthropogenic origin have been noted previously. Such changes are considered to have a substantial impact on the liquid phase and solid matrix properties. ENMs reach the land surface through many pathways during and after their beneficial use. Once in the soil, ENMs move as suspended particles in aqueous solution. Dissolution, aggregation and deposition are the primary processes governing their interaction with the soil solid phase and their redistribution from the land surface to the groundwater. We argue that irreversible deposition of ENMs occurring under specific conditions (e.g., in arid and semi-arid environments) may lead to irreversible changes in soil matrix structure and properties. Results from our research on metal and metal oxides ENMs (e.g., CuO, Ag) and from literature on carbon based nanomaterials will be presented in support of our hypothesis.

  20. Tailoring the emissive properties of photocathodes through materials engineering: Ultra-thin multilayers

    NASA Astrophysics Data System (ADS)

    Velázquez, Daniel; Seibert, Rachel; Ganegoda, Hasitha; Olive, Daniel; Rice, Amy; Logan, Kevin; Yusof, Zikri; Spentzouris, Linda; Terry, Jeff

    2016-01-01

    We report on an experimental verification that emission properties of photocathodes can be manipulated through the engineering of the surface electronic structure. Ultrathin multilayered MgO/Ag(0 0 1)/MgO films were grown by pulsed laser deposition, tuning the thickness n of the flanking MgO layers to 0, 2, 3, and 4 monolayers. We observed an increase in quantum efficiency and simultaneous decrease in work function with layer thickness. The scale and trend direction of measurements are in good but not excellent agreement with theory. Angle resolved photoemission data for the multilayered sample n = 3 showed that the emission profile has a metallic-like momentum dispersion. Deviations from theoretical predictions [K. Németh et al., PRL 104, 046801 (2010)] are attributed to imperfections of real surfaces in contrast with the ideal surfaces of the calculation. Photoemissive properties of cathodes are critical for electron beam applications such as photoinjectors for Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). An ideal photoemitter has a high quantum efficiency, low work function, low intrinsic emittance and long lifetime. It has been demonstrated here that emission properties may be systematically tailored by control of layer thickness in ultrathin multilayered structures. The reproducibility of the emission parameters under specific growth conditions is excellent, even though the interfaces themselves have varying degrees of roughness.

  1. Gyrokinetic Simulation of Global Turbulent Transport Properties in Tokamak Experiments

    SciTech Connect

    Wang, W.X.; Lin, Z.; Tang, W.M.; Lee, W.W.; Ethier, S.; Lewandowski, J.L.V.; Rewoldt, G.; Hahm, T.S.; Manickam, J.

    2006-01-01

    A general geometry gyro-kinetic model for particle simulation of plasma turbulence in tokamak experiments is described. It incorporates the comprehensive influence of noncircular cross section, realistic plasma profiles, plasma rotation, neoclassical (equilibrium) electric fields, and Coulomb collisions. An interesting result of global turbulence development in a shaped tokamak plasma is presented with regard to nonlinear turbulence spreading into the linearly stable region. The mutual interaction between turbulence and zonal flows in collisionless plasmas is studied with a focus on identifying possible nonlinear saturation mechanisms for zonal flows. A bursting temporal behavior with a period longer than the geodesic acoustic oscillation period is observed even in a collisionless system. Our simulation results suggest that the zonal flows can drive turbulence. However, this process is too weak to be an effective zonal flow saturation mechanism.

  2. Properties of numerical experiments in chaotic dynamical systems

    NASA Astrophysics Data System (ADS)

    Yuan, Guo-Cheng

    1999-10-01

    This dissertation contains four projects that I have worked on during my graduate study at University of Maryland at College Park. These projects are all related to numerical simulations of chaotic dynamical systems. In particular, the two conjectures in Chapter 1 are inspired by the numerical discoveries in Hunt and Ott [1, 2]. In Chapter 2, statistical properties of scalar transport in chaotic flows are investigated by using numerical simulations. In Chapters 3 and 4, I take a different angle and discuss the limitations of numerical simulations; i.e. for certain ``bad'' systems numerical simulations will yield incorrect or at least unreliable results no matter how many digits of precision are used. Chapter 1 discusses the properties of optimal orbits. Given a dynamical system and a function f from the state space to the real numbers, an optimal orbit for f is an orbit over which the average of f is maximal. In this chapter we discuss some basic mathematical aspects of optimal orbits: existence, sensitivity to perturbations of f, and approximability by periodic orbits with low period. For hyperbolic systems, we conjecture that (1)for (topologically) generic smooth functions, there exists an optimal periodic orbit, and (2)the optimal average can be approximated exponentially well by averages over certain periodic orbits with increasing period. In Chapter 2 we theoretically study the power spectrum of passive scalars transported in two dimensional chaotic fluid flows. Using a wave-packet method introduced by Antonsen et al. [3] [4], we numerically investigate several model flows, and confirm that the power spectrum has the k -l- scaling predicted by Batchelor [5]. In Chapter 3 we consider a class of nonhyperbolic systems, for which there are two fixed points in an attractor having a dense trajectory; the unstable manifold of one fixed point has dimension one and the other's is two dimensional. Under the condition that there exists a direction which is more expanding

  3. U.S. Army Corps of Engineers Waste Experiences: More Than You May Think

    SciTech Connect

    Hays, D. C.; Honerlah, H. B.

    2003-02-24

    U.S. Army Corps of Engineers (USACE) works with other federal, and state agencies through several different programs on numerous Hazardous, Toxic, and Radioactive Waste (HTRW) sites. Formerly Utilized Sites Remediation Program (FUSRAP), Formerly Used Defense Sites (FUDS), EPA Superfund, Installation Restoration, Army Deactivated Nuclear Reactor Program, and many other programs present hazardous, radioactive, and mixed waste issues. While the USACE has a reputation of excellent dirt movers, little is discussed of our other waste management experiences. This paper discusses some of the challenges facing the Health Physics (HP) staff of the USACE. The HP staff is currently organized as one team, the Radiation Safety Support Team (RSST), comprised of 15 individuals at 6 locations across the country. With typical RSST missions including HP consultation to USACE activities world wide, many waste challenges arise. These challenges have involved radioactive wastes of all classifications and stability. Sealed and unsealed sources; instruments and dials; contaminated earth and debris; liquids; lab, reactor, and medical wastes are all successfully managed by the USACE. USACE also develops, evaluates, and utilizes waste treatment Types of radioactive waste at HTRW sites include: Low Level Radioactive Wastes (LLRW) (class A, B, C, and greater than C), 11e.(2), Transuranic (TRU), Mixed, and Naturally Occurring (NORM/TENORM).

  4. Hypersonic Engine Leading Edge Experiments in a High Heat Flux, Supersonic Flow Environment

    NASA Technical Reports Server (NTRS)

    Gladden, Herbert J.; Melis, Matthew E.

    1994-01-01

    A major concern in advancing the state-of-the-art technologies for hypersonic vehicles is the development of an aeropropulsion system capable of withstanding the sustained high thermal loads expected during hypersonic flight. Three aerothermal load related concerns are the boundary layer transition from laminar to turbulent flow, articulating panel seals in high temperature environments, and strut (or cowl) leading edges with shock-on-shock interactions. A multidisciplinary approach is required to address these technical concerns. A hydrogen/oxygen rocket engine heat source has been developed at the NASA Lewis Research Center as one element in a series of facilities at national laboratories designed to experimentally evaluate the heat transfer and structural response of the strut (or cowl) leading edge. A recent experimental program conducted in this facility is discussed and related to cooling technology capability. The specific objective of the experiment discussed is to evaluate the erosion and oxidation characteristics of a coating on a cowl leading edge (or strut leading edge) in a supersonic, high heat flux environment. Heat transfer analyses of a similar leading edge concept cooled with gaseous hydrogen is included to demonstrate the complexity of the problem resulting from plastic deformation of the structures. Macro-photographic data from a coated leading edge model show progressive degradation over several thermal cycles at aerothermal conditions representative of high Mach number flight.

  5. Issues in nanocomposite ceramic engineering: focus on processing and properties of alumina-based composites.

    PubMed

    Palmero, Paola; Kern, Frank; Sommer, Frank; Lombardi, Mariangela; Gadow, Rainer; Montanaro, Laura

    2014-12-30

    Ceramic nanocomposites, containing at least one phase in the nanometric dimension, have received special interest in recent years. They have, in fact, demonstrated increased performance, reliability and lifetime with respect to monolithic ceramics. However, a successful approach to the production of tailored composite nanostructures requires the development of innovative concepts at each step of manufacturing, from the synthesis of composite nanopowders, to their processing and sintering.This review aims to deepen understanding of some of the critical issues associated with the manufacturing of nanocomposite ceramics, focusing on alumina-based composite systems. Two case studies are presented and briefly discussed. The former illustrates the benefits, in terms of sintered microstructure and related mechanical properties, resulting from the application of an engineering approach to a laboratory-scale protocol for the elaboration of nanocomposites in the system alumina-ZrO2-YAG (yttrium aluminium garnet). The latter illustrates the manufacturing of alumina-based composites for large-scale applications such as cutting tools, carried out by an injection molding process. The need for an engineering approach to be applied in all processing steps is demonstrated also in this second case study, where a tailored manufacturing process is required to obtain the desired results.

  6. Recombinant human gelatin substitute with photoreactive properties for cell culture and tissue engineering.

    PubMed

    Kitajima, Takashi; Obuse, Sei; Adachi, Takahiro; Tomita, Masahiro; Ito, Yoshihiro

    2011-10-01

    The human recombinant collagen I α1 chain monomer (rh-gelatin) was modified by the incorporation of an azidophenyl group to prepare photoreactive human gelatin (Az-rh-gelatin), with approximately 90% of the lysine residues conjugated with azidobenzoic acid. Slight changes in conformation (circular dichroism spectra) and thermal properties (gelation and melting points) were noticed after modification. Ultraviolet (UV) irradiation could immobilize the Az-rh-gelatin on polymer surfaces, such as polystyrene and polytetrafluoroethylene. Az-rh-gelatin was stably retained on the polymer surfaces, while unmodified gelatin was mostly lost by brief washing. Human mesenchymal cells grew more efficiently on the immobilized surface than on the coated surface. The immobilized Az-rh-gelatin on the polymer surfaces was able to capture engineered growth factors with collagen affinity, and the bound growth factors stimulated the growth of cells dose-dependently. It was also possible to immobilize Az-rh-gelatin in micropatterns (stripe, grid, and so on) using photomasks, and the cells grew according to the patterns. These results suggest that the photoreactive human gelatin, in combination with collagen-binding growth factors, will be clinically useful for surface modification of synthetic materials for cell culture systems and tissue engineering.

  7. Engineering properties of water/wastewater-treatment sludge modified by hydrated lime, fly ash and loess.

    PubMed

    Lim, Sungjin; Jeon, Wangi; Lee, Jaebok; Lee, Kwanho; Kim, Namho

    2002-10-01

    The purpose of this research was to present engineering properties of modified sludge from water/wastewater treatment by modifiers such as hydrated lime, loess, and fly ash. The proper mixing ratio was determined to hold the pH of the modified sludge above 12.0 for 2 h. Laboratory tests carried out in this research included particle analysis, compaction and CBR, SEM and X-ray diffraction, unconfined compression test, permeability test, and TCLP test. The main role of lime was to sterilize microorganisms in the sludge. The unconfined strength of the modified sludge by fly ash and loess satisfied the criteria for construction materials, which was above 100 kPa. The permeability of all the mixtures was around 1.0 x 10(-7) cm/s. Extraction tests for hazardous components in modified sludge revealed below the regulated criteria, especially for cadmium, copper, and lead. The present study suggested that the use of lime, fly ash, and loess be an another alternative to modify or stabilize water/wastewater treatment sludge as construction materials in civil engineering.

  8. Identifying and Engineering the Electronic Properties of the Resistive Switching Interface

    NASA Astrophysics Data System (ADS)

    Li, H.; Zhang, Z.; Shi, L. P.

    2016-02-01

    The resistive switching interface is promising for building random access memory devices with electroforming-free characteristics, rectification functionality and highly reproducible resistive switching performance. The electronic structures of the resistive switching interface are important not only from a fundamental point of view, but also from the fascinating perspective of interface engineering for high performance devices. However, the electronic properties of typical resistive switching interfacial structures at an atomic level are less well understood, compared to those of bulky resistive switching structures. In this work, we study the electronic structures of two typical resistive switching interfacial structures, TiO2/Ti4O7 and Ta2O5/TaO2, using the screened exchange (sX-LDA) functional. We uncover that the system Fermi energies of both interfaces are just above the conduction band edge of the corresponding stoichiometric oxides. According to the defect charge transition levels, the oxygen vacancy is stabilized at the -2 charged state in Ta2O5 and TiO2 where the switching takes place. However, it is desirable for the +2 charged oxygen vacancy to be stabilized to achieve controlled resistive switching under the electrical field. We propose to introduce interfacial dopants to shift the system Fermi energies downward so that the +2 charged oxygen vacancy can be stable. Several dipole models are presented to account for the ability of the Fermi level to shift due to the interfacial dopants. These methods are readily applicable to interface engineering for high performance devices.

  9. Displaying and evaluating engineering properties and natural hazards using geomorphic mapping techniques: Telluride, Colorado

    SciTech Connect

    Gunawan, I.; Giardino, J.R.; Tchakerian, V.P. . Geography Dept.)

    1992-01-01

    Telluride, located in the San Juan mountains of southwestern Colorado, is situated in a glacially carved, fluvially modified alpine valley. Today this chic setting is experiencing rapid urban development resulting from flourishing tourist traffic during both the winter ski season and the summer vacation period. A new development, Mountain Village, is being built on an extensive and complex landslide that has only received superficial scrutiny. Recent fast growth is placing considerable pressure on pristine, undeveloped land. This timely quandary incorporates the interaction between prospective development, geomorphic processes, engineering factors, economic feasibility, and landuse adjudication. In an attempt to respond to these issues the State of Colorado enacted Senate Bill 35 (1972) and House Bills 1034 (1974) and 1041 (1974), all mandating assessment of the natural hazards of an area, preparatory to development. The key to evaluating the natural hazards is to comprehend the geomorphic processes. The area is highly-faulted with associated mineralization. Whereas the upper slopes are composed of massive rhyodacitic-tuff breccias and flows, the valley is sculpted from shales, sandstones, and conglomerates. Several periods of glaciation occurred in the area. Glacial till, talus slopes, avalanche chutes and cones, rock glaciers, alluvium, and landslides have been identified in the field and mapped on aerial photographs. Many of the slopes in the area are active. The authors have constructed a geomorphic map (1:12,500) that shows geology, landforms, geomorphic processes and engineering properties. This map can be used by regulatory agencies in identifying areas of natural hazards potentially sensitive to development.

  10. Preparation and mechanical property of a novel 3D porous magnesium scaffold for bone tissue engineering.

    PubMed

    Zhang, Xue; Li, Xiao-Wu; Li, Ji-Guang; Sun, Xu-Dong

    2014-09-01

    Porous magnesium has been recently recognized as a biodegradable metal for bone substitute applications. A novel porous Mg scaffold with three-dimensional (3D) interconnected pores and with a porosity of 33-54% was produced by the fiber deposition hot pressing (FDHP) technology. The microstructure and morphologies of the porous Mg scaffold were characterized by scanning electron microscopy (SEM), and the effects of porosities on the microstructure and mechanical properties of the porous Mg were investigated. Experimental results indicate that the measured Young's modulus and compressive strength of the Mg scaffold are ranged in 0.10-0.37 GPa, and 11.1-30.3 MPa, respectively, which are fairly comparable to those of cancellous bone. Such a porous Mg scaffold having a 3D interconnected network structure has the potential to be used in bone tissue engineering.

  11. Engineering optical properties of a graphene oxide metamaterial assembled in microfluidic channels.

    PubMed

    Kravets, V G; Marshall, O P; Nair, R R; Thackray, B; Zhukov, A; Leng, J; Grigorenko, A N

    2015-01-26

    The dense packing of two dimensional flakes by van der Waals forces has enabled the creation of new metamaterials with desirable optical properties. Here we assemble graphene oxide sheets into a three dimensional metamaterial using a microfluidic technique and confirm their ordering via measurements of ellipsometric parameters, polarized optical microscopy, polarized transmission spectroscopy, infrared spectroscopy and scanning electron microscopy. We show that the produced metamaterials demonstrate strong in-plane optical anisotropy (Δn≈0.3 at n≈1.5-1.8) combined with low absorption (k<0.1) and compare them with as-synthesized samples of graphene oxide paper. Our results pave the way for engineered birefringent metamaterials on the basis of two dimensional atomic crystals including graphene and its derivatives.

  12. Exploring the Properties of Genetically Engineered Silk-Elastin-Like Protein Films.

    PubMed

    Machado, Raul; da Costa, André; Sencadas, Vitor; Pereira, Ana Margarida; Collins, Tony; Rodríguez-Cabello, José Carlos; Lanceros-Méndez, Senentxu; Casal, Margarida

    2015-12-01

    Free standing films of a genetically engineered silk-elastin-like protein (SELP) were prepared using water and formic acid as solvents. Exposure to methanol-saturated air promoted the formation of aggregated β-strands rendering aqueous insolubility and improved the mechanical properties leading to a 10-fold increase in strain-to-failure. The films were optically clear with resistivity values similar to natural rubber and thermally stable up to 180 °C. Addition of glycerol showed to enhance the flexibility of SELP/glycerol films by interacting with SELP molecules through hydrogen bonding, interpenetrating between the polymer chains and granting more conformational freedom. This detailed characterization provides cues for future and unique applications using SELP based biopolymers.

  13. On the relationship between engineering properties and delamination of composite materials

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.

    1981-01-01

    Delamination of composite materials has been investigated with emphasis on the relationship between the engineering properties of the individual layers and edge effects. It is shown that interlaminar shear stresses are primarily a function of the mismatch in coefficients of mutual influence which can be as much as ten times greater than the mismatch in Poisson's ratio. The mismatch in coefficients of mutual influence has a high peak value in the 10-15 deg range for plus or minus theta laminates (where theta is the angle of fiber orientation measured from the axis of the coupon). This mismatch is reduced by a factor of two when the plus or minus theta layers are interspersed between 0 and 90 deg layers. Application of the results to composite design is illustrated by an example.

  14. NASA's Robotics Mining Competition Provides Undergraduates Full Life Cycle Systems Engineering Experience

    NASA Technical Reports Server (NTRS)

    Stecklein, Jonette

    2017-01-01

    NASA has held an annual robotic mining competition for teams of university/college students since 2010. This competition is yearlong, suitable for a senior university engineering capstone project. It encompasses the full project life cycle from ideation of a robot design to actual tele-operation of the robot in simulated Mars conditions mining and collecting simulated regolith. A major required element for this competition is a Systems Engineering Paper in which each team describes the systems engineering approaches used on their project. The score for the Systems Engineering Paper contributes 25% towards the team's score for the competition's grand prize. The required use of systems engineering on the project by this competition introduces the students to an intense practical application of systems engineering throughout a full project life cycle.

  15. Promoting cross-departmental initiatives for a global dimension in engineering education: the Imperial College experience

    NASA Astrophysics Data System (ADS)

    Alpay, E.; Ahearn, A. L.; Bull, A. M. J.

    2011-06-01

    Cross-departmental schemes to broaden the inter-professional and skills-focused development of engineering students, and to emphasise engineering in its context of societal priorities, are presented. The central coordination of the schemes has streamlined implementation of the developments and promoted a culture of shared responsibility for engineering education. A description of the coordination effort, and subsequent mechanisms for promoting strategic educational development, is given. This will be of value to institutions that are attempting to organise educational initiatives across multiple engineering departments. Examples are given to demonstrate the range of learning outcomes that can be achieved through such cross-departmental approaches. Evaluation data are also presented on the value and impact of these approaches. Specific schemes that are described include: the Engineering Impact series of lectures; flexible timetabling for shared option-courses across departments; a common framework for engineering ethics engagement; the establishment of a new academic role for the support of student-led projects.

  16. High-frequency viscoelastic shear properties of vocal fold tissues: implications for vocal fold tissue engineering.

    PubMed

    Teller, Sean S; Farran, Alexandra J E; Xiao, Longxi; Jiao, Tong; Duncan, Randall L; Clifton, Rodney J; Jia, Xinqiao

    2012-10-01

    The biomechanical function of the vocal folds (VFs) depends on their viscoelastic properties. Many conditions can lead to VF scarring that compromises voice function and quality. To identify candidate replacement materials, the structure, composition, and mechanical properties of native tissues need to be understood at phonation frequencies. Previously, the authors developed the torsional wave experiment (TWE), a stress-wave-based experiment to determine the linear viscoelastic shear properties of small, soft samples. Here, the viscoelastic properties of porcine and human VFs were measured over a frequency range of 10-200 Hz. The TWE utilizes resonance phenomena to determine viscoelastic properties; therefore, the specimen test frequency is determined by the sample size and material properties. Viscoelastic moduli are reported at resonance frequencies. Structure and composition of the tissues were determined by histology and immunochemistry. Porcine data from the TWE are separated into two groups: a young group, consisting of fetal and newborn pigs, and an adult group, consisting of 6-9-month olds and 2+-year olds. Adult tissues had an average storage modulus of 2309±1394 Pa and a loss tangent of 0.38±0.10 at frequencies of 36-200 Hz. The VFs of young pigs were significantly more compliant, with a storage modulus of 394±142 Pa and a loss tangent of 0.40±0.14 between 14 and 30 Hz. No gender dependence was observed. Histological staining showed that adult porcine tissues had a more organized, layered structure than the fetal tissues, with a thicker epithelium and a more structured lamina propria. Elastin fibers in fetal VF tissues were immature compared to those in adult tissues. Together, these structural changes in the tissues most likely contributed to the change in viscoelastic properties. Adult human VF tissues, recovered postmortem from adult patients with a history of smoking or disease, had an average storage modulus of 756±439 Pa and a loss tangent of 0

  17. Elastic, permeability and swelling properties of human intervertebral disc tissues: A benchmark for tissue engineering.

    PubMed

    Cortes, Daniel H; Jacobs, Nathan T; DeLucca, John F; Elliott, Dawn M

    2014-06-27

    The aim of functional tissue engineering is to repair and replace tissues that have a biomechanical function, i.e., connective orthopaedic tissues. To do this, it is necessary to have accurate benchmarks for the elastic, permeability, and swelling (i.e., biphasic-swelling) properties of native tissues. However, in the case of the intervertebral disc, the biphasic-swelling properties of individual tissues reported in the literature exhibit great variation and even span several orders of magnitude. This variation is probably caused by differences in the testing protocols and the constitutive models used to analyze the data. Therefore, the objective of this study was to measure the human lumbar disc annulus fibrosus (AF), nucleus pulposus (NP), and cartilaginous endplates (CEP) biphasic-swelling properties using a consistent experimental protocol and analyses. The testing protocol was composed of a swelling period followed by multiple confined compression ramps. To analyze the confined compression data, the tissues were modeled using a biphasic-swelling model, which augments the standard biphasic model through the addition of a deformation-dependent osmotic pressure term. This model allows considering the swelling deformations and the contribution of osmotic pressure in the analysis of the experimental data. The swelling stretch was not different between the disc regions (AF: 1.28±0.16; NP: 1.73±0.74; CEP: 1.29±0.26), with a total average of 1.42. The aggregate modulus (Ha) of the extra-fibrillar matrix was higher in the CEP (390kPa) compared to the NP (100kPa) or AF (30kPa). The permeability was very different across tissue regions, with the AF permeability (64 E(-16)m(4)/Ns) higher than the NP and CEP (~5.5 E(-16)m(4)/Ns). Additionally, a normalized time-constant (3000s) for the stress relaxation was similar for all the disc tissues. The properties measured in this study are important as benchmarks for tissue engineering and for modeling the disc's mechanical

  18. The industrial RB211-24 gas engine: initial experience in service offshore

    SciTech Connect

    Soinne, P.E.

    1983-01-01

    The Industrial RB211 gas engine is derived from the RB211 turbofan aero engine which in its various marks powers all Lockheed Tristars and a proportion of Boeing 747 airliners. The design and development programme of the industrial engine commenced in 1972. It arose out of an earlier feasibility study for a second generation marine propulsion engine. The industrial programme was specifically aimed at the production of a gas-fuelled base load machine for gas pumping and transmission applications. The engine was designated the Industrial RB211-22, being derived from the RB211-22 aero engine, the single mark of engine available at that time. The first field trials gas generator entered service in late 1974 in a transmission pipeline gas pumping application in Canada. Since then the RB211-22 engine has accumulated over 140,000 hours of operation in twelve onshore installations. Design and development of an uprated version of the engine began in early 1976. This was designated RB211-24, since it utilized the improved turbine technology of the RB211-524 aero engine introduced for the Boeing 747 and later versions of Tristar. With offshore applications in mind, the validation of improved corrosion resistant turbine materials was an integral part of the development programme. In consequence of this, the engine was available for both offshore and onshore applications as released for production. The first RB211-24 engines entered service in late 1980 in offshore applications on the Leman AK platform and another North Sea Gas production platform. There are now a total of fifteen RB211-24 installations which have accumulated over 53,000 hours of operation both onshore and offshore.

  19. Biaxial Stretch Improves Elastic Fiber Maturation, Collagen Arrangement, and Mechanical Properties in Engineered Arteries.

    PubMed

    Huang, Angela H; Balestrini, Jenna L; Udelsman, Brooks V; Zhou, Kevin C; Zhao, Liping; Ferruzzi, Jacopo; Starcher, Barry C; Levene, Michael J; Humphrey, Jay D; Niklason, Laura E

    2016-06-01

    Tissue-engineered blood vessels (TEVs) are typically produced using the pulsatile, uniaxial circumferential stretch to mechanically condition and strengthen the arterial grafts. Despite improvements in the mechanical integrity of TEVs after uniaxial conditioning, these tissues fail to achieve critical properties of native arteries such as matrix content, collagen fiber orientation, and mechanical strength. As a result, uniaxially loaded TEVs can result in mechanical failure, thrombus, or stenosis on implantation. In planar tissue equivalents such as artificial skin, biaxial loading has been shown to improve matrix production and mechanical properties. To date however, multiaxial loading has not been examined as a means to improve mechanical and biochemical properties of TEVs during culture. Therefore, we developed a novel bioreactor that utilizes both circumferential and axial stretch that more closely simulates loading conditions in native arteries, and we examined the suture strength, matrix production, fiber orientation, and cell proliferation. After 3 months of biaxial loading, TEVs developed a formation of mature elastic fibers that consisted of elastin cores and microfibril sheaths. Furthermore, the distinctive features of collagen undulation and crimp in the biaxial TEVs were absent in both uniaxial and static TEVs. Relative to the uniaxially loaded TEVs, tissues that underwent biaxial loading remodeled and realigned collagen fibers toward a more physiologic, native-like organization. The biaxial TEVs also showed increased mechanical strength (suture retention load of 303 ± 14.53 g, with a wall thickness of 0.76 ± 0.028 mm) and increased compliance. The increase in compliance was due to combinatorial effects of mature elastic fibers, undulated collagen fibers, and collagen matrix orientation. In conclusion, biaxial stretching is a potential means to regenerate TEVs with improved matrix production, collagen organization, and mechanical

  20. Development of the mechanical properties of engineered skin substitutes after grafting to full-thickness wounds.

    PubMed

    Sander, Edward A; Lynch, Kaari A; Boyce, Steven T

    2014-05-01

    Engineered skin substitutes (ESSs) have been reported to close full-thickness burn wounds but are subject to loss from mechanical shear due to their deficiencies in tensile strength and elasticity. Hypothetically, if the mechanical properties of ESS matched those of native skin, losses due to shear or fracture could be reduced. To consider modifications of the composition of ESS to improve homology with native skin, biomechanical analyses of the current composition of ESS were performed. ESSs consist of a degradable biopolymer scaffold of type I collagen and chondroitin-sulfate (CGS) that is populated sequentially with cultured human dermal fibroblasts (hF) and epidermal keratinocytes (hK). In the current study, the hydrated biopolymer scaffold (CGS), the scaffold populated with hF dermal skin substitute (DSS), or the complete ESS were evaluated mechanically for linear stiffness (N/mm), ultimate tensile load at failure (N), maximum extension at failure (mm), and energy absorbed up to the point of failure (N-mm). These biomechanical end points were also used to evaluate ESS at six weeks after grafting to full-thickness skin wounds in athymic mice and compared to murine autograft or excised murine skin. The data showed statistically significant differences (p <0.05) between ESS in vitro and after grafting for all four structural properties. Grafted ESS differed statistically from murine autograft with respect to maximum extension at failure, and from intact murine skin with respect to linear stiffness and maximum extension. These results demonstrate rapid changes in mechanical properties of ESS after grafting that are comparable to murine autograft. These values provide instruction for improvement of the biomechanical properties of ESS in vitro that may reduce clinical morbidity from graft loss.

  1. Exploring the experiences of female students in introductory project-based engineering courses at two- and four-year institutions

    NASA Astrophysics Data System (ADS)

    Swan, Amy K.

    2011-12-01

    This qualitative study explored the experiential and contextual factors that shaped female students' pathways into introductory project-based engineering classes at two community colleges and one four-year institution, as well as female students' experiences within and outside of these classes. The study was framed by Social Cognitive Career Theory (SCCT) (Lent, Brown & Hackett, 1996) and Bronfenbrenner's (1979) ecological systems theory. Findings were based on analyses of data gathered through multiple methods: observations; individual interviews with female students; focus group interviews with project teams; and document collection. The findings of this study revealed that while positive experiences with math or science were a likely pre-cursor to engineering interest, experiential learning appeared to be a more powerful force in fostering students' engineering interest. Specifically, participants developed an interest in engineering through academic, professional, and extracurricular engineering- and design-related activities that familiarized them with the tasks and skills involved in engineering work and helped them develop a sense of selfefficacy with regard to this work. Interest and self-efficacy, in turn, played a role in students' postsecondary educational decision-making processes, as did contextual factors including families and finances. This study's findings also showed that participants' project teams were a critically important microsystem within participants' ecological environments. Within this sometimes "chilly" microsystem, female students negotiated intrateam processes, which were in some cases affected by gender norms. Intrateam processes that influenced female students' project-based learning experiences included: interpersonal dynamics; leadership; and division of labor. This study also identified several ways in which the lived experiences of participants at the community colleges were different from, or similar to, those of participants

  2. Peer-Assisted Tutoring in a Chemical Engineering Curriculum: Tutee and Tutor Experiences

    ERIC Educational Resources Information Center

    Kieran, Patricia; O'Neill, Geraldine

    2009-01-01

    Peer-Assisted Tutorials (PATs), a form of Peer-Assisted Learning (PAL), were introduced to a conventional 4-year honours degree programme in Chemical Engineering. PATs were designed to support students in becoming more self-directed in their learning, to develop student confidence in tackling Chemical Engineering problems and to promote effective…

  3. Design Practices of Preservice Elementary Teachers in an Integrated Engineering and Literature Experience

    ERIC Educational Resources Information Center

    Wendell, Kristen Bethke

    2014-01-01

    The incorporation of engineering practices and core ideas into the "Next Generation Science Standards" at the elementary school level provides exciting opportunities but also raises important questions about the preparation of new elementary teachers. Both the teacher education and engineering education communities have a limited…

  4. Exploring How Experience with Planning Impacts First Grade Students' Planning and Solutions to Engineering Design Problems

    ERIC Educational Resources Information Center

    Portsmore, Merredith D.

    2010-01-01

    This dissertation presents research that investigated how first grade students' ability to construct solutions and to plan through drawing for engineering design problems is related to their participation in a LEGO-based engineering curriculum with two variations on the instruction for planning. The quasi-experimental design engaged two first…

  5. Male Engineers: An Interpretive Phenomenological Analysis of the Experiences of Persistence in Higher Education

    ERIC Educational Resources Information Center

    Ecklund, Adam P.

    2013-01-01

    More and more engineering programs have become concerned with retention and persistence in their degrees, because about half of their students either change majors or do not graduate at all (Center for Institutional Data Exchange and Analysis, 2000). Male students were chosen for this study because they make up 92.9% of all civil engineers, 90.6%…

  6. Exploration of the Lived Experiences of Undergraduate Science, Technology, Engineering, and Mathematics Minority Students

    ERIC Educational Resources Information Center

    Snead-McDaniel, Kimberly

    2010-01-01

    An expanding ethnicity gap exists in the number of students pursuing science, technology, engineering, and mathematics (STEM) careers in the United States. The National Action Council for Minorities in Engineering revealed that the number of minorities pursuing STEM degrees and careers has declined over the past few years. The specific origins of…

  7. Challenges of Engineering Higher Education in a Transitional Economy: A Russian Experience

    ERIC Educational Resources Information Center

    Matveev, Alexei; Matveev, Olga; Zhukov, Vassily

    2005-01-01

    Education and training serve as critical elements of advancement of a nation's economy in transition. The restructuring of the power engineering industry in Russia has called for a fast implementation of new management system in electric power engineering and radical training of professional managers at different levels in organizations.…

  8. New Architectures for Presenting Search Results Based on Web Search Engines Users Experience

    ERIC Educational Resources Information Center

    Martinez, F. J.; Pastor, J. A.; Rodriguez, J. V.; Lopez, Rosana; Rodriguez, J. V., Jr.

    2011-01-01

    Introduction: The Internet is a dynamic environment which is continuously being updated. Search engines have been, currently are and in all probability will continue to be the most popular systems in this information cosmos. Method: In this work, special attention has been paid to the series of changes made to search engines up to this point,…

  9. Sustaining Liminality: Experiences and Negotiations of International Females in U.S. Engineering Graduate Programs

    ERIC Educational Resources Information Center

    Dutta, Debalina

    2012-01-01

    This project examines the intersectionalities of international females in engineering graduate programs of the United States, using frameworks of sustainability and liminality theory. According to Dutta and Kisselburgh (2011) international females in graduate engineering constitute the "minorities of minorities," not only in terms of…

  10. Learning from Experience: The Realities of Developing Mathematics Courses for an Online Engineering Programme

    ERIC Educational Resources Information Center

    Quinn, Diana; Albrecht, Amie; Webby, Brian; White, Kevin

    2015-01-01

    Rarely do university departments of mathematics redesign their basic mathematics courses. Through developing an online version of our associate degree in engineering in collaboration with Open Universities Australia, we redesigned the first in a sequence of five engineering mathematics courses. The online cohort proved different to our…

  11. A Multi- and Cross-Disciplinary Capstone Experience in Engineering Art: Animatronic Polar Bear

    ERIC Educational Resources Information Center

    Sirinterlikci, Arif; Toukonen, Kayne; Mason, Steve; Madison, Russel

    2005-01-01

    An animatronic robot was designed and constructed for the 2003 Annual Student Robotic Technology and Engineering Challenge organized by the Robotics International (RI) association of the Society of Manufacturing Engineers (SME). It was also the senior capstone design project for two of the design team members. After a thorough study of body and…

  12. Building a Competency Taxonomy to Guide Experience Acceleration of Lead Program Systems Engineers

    DTIC Science & Technology

    2011-04-01

    2010), a flurry of activity to develop systems engineering compe- tency models has occurred over the past decade (Squires, 2011; Ferris, 2010; Kasser ...university, UK, april 20-23 2009. Kasser , J, Frank, M, and Zhao, Y. Y. “Assessing the competencies of systems engineers.” In Proceedings of the 7Th Bi

  13. Promoting Cross-Departmental Initiatives for a Global Dimension in Engineering Education: The Imperial College Experience

    ERIC Educational Resources Information Center

    Alpay, E.; Ahearn, A. L.; Bull, A. M. J.

    2011-01-01

    Cross-departmental schemes to broaden the inter-professional and skills-focused development of engineering students, and to emphasise engineering in its context of societal priorities, are presented. The central coordination of the schemes has streamlined implementation of the developments and promoted a culture of shared responsibility for…

  14. A Successful Experience of ABET Accreditation of an Electrical Engineering Program

    ERIC Educational Resources Information Center

    Al-Yahya, S. A.; Abdel-Halim, M. A.

    2013-01-01

    The procedures followed and the various factors that led to the ABET accreditation of the College of Engineering, Qassim University, Buraidah, Saudi Arabia, are illustrated and evaluated for the benefit of other similar colleges. Taking the Electrical Engineering (EE) program as an example, this paper describes the procedures followed to implement…

  15. Arginine deiminase: recent advances in discovery, crystal structure, and protein engineering for improved properties as an anti-tumor drug.

    PubMed

    Han, Rui-Zhi; Xu, Guo-Chao; Dong, Jin-Jun; Ni, Ye

    2016-06-01

    Arginine deiminase (ADI) is an important arginine-degrading enzyme with wide applications, in particular as an anti-cancer agent for the therapy of arginine-auxotrophic tumors. In recent years, novel ADIs with excellent properties have been identified from various organisms, and crystal structures of ADI were investigated. To satisfy the requirements of potential therapeutic applications, protein engineering has been performed to improve the activity and properties of ADIs. In this mini-review, we systematically summarized the latest progress on identification and crystal structure of ADIs, and protein engineering strategies for improved enzymatic properties, such as pH optimum, K m and k cat values, and thermostability. We also outlined the PEGylation of ADI for improved circulating half-life and immunogenicity, as well as their performance in clinical trials. Finally, perspectives on extracellular secretion and property improvement of ADI were discussed.

  16. Characterizing the viscoelastic properties of thin hydrogel-based constructs for tissue engineering applications.

    PubMed

    Ahearne, Mark; Yang, Ying; El Haj, Alicia J; Then, Kong Y; Liu, Kuo-Kang

    2005-12-22

    We present a novel indentation method for characterizing the viscoelastic properties of alginate and agarose hydrogel based constructs, which are often used as a model system of soft biological tissues. A sensitive long working distance microscope was used for measuring the time-dependent deformation of the thin circular hydrogel membranes under a constant load. The deformation of the constructs was measured laterally. The elastic modulus as a function of time can be determined by a large deformation theory based on Mooney-Rivlin elasticity. A viscoelastic theory, Zener model, was applied to correlate the time-dependent deformation of the constructs with various gel concentrations, and the creep parameters can therefore be quantitatively estimated. The value of Young's modulus was shown to increase in proportion with gel concentration. This finding is consistent with other publications. Our results also showed the great capability of using the technique to measure gels with incorporated corneal stromal cells. This study demonstrates a novel and convenient technique to measure mechanical properties of hydrogel in a non-destructive, online and real-time fashion. Thus this novel technique can become a valuable tool for soft tissue engineering.

  17. Dynamic control over cell adhesive properties using molecular-based surface engineering strategies.

    PubMed

    Robertus, Jort; Browne, Wesley R; Feringa, Ben L

    2010-01-01

    In complex organisms, cells are often dependent on their extracellular matrix (ECM) for structural integrity, the mechanical properties of tissues, and for signaled regulation of cellular processes including adhesion, migration, growth, secretion, gene expression and apoptosis. Achieving dynamic control, i.e. by using an external stimulus, over the interactions between cells and artificial interfaces holds considerable promise in tissue engineering, medicine, cell biology and immunology. For example, improved spatial control over cell-surface interaction is potentially useful in the design of cell-based screening devices. Dynamic control over SAMs for cell adhesion provides an additional handle to direct and study the attachment of cells to surfaces, e.g., in studying cell spreading from a predetermined pattern in order to screen the cytotoxicity of drug candidates. However, 'reversible' control of cell adhesion onto substrates is an area that is still in its infancy. In this critical review recent developments in cell adhesion of mammalian cells to SAM-modified surfaces, the physical properties of which can be controlled by an external stimulus, e.g. by light, electrochemistry, etc., are discussed (118 references).

  18. Engineering and Probing Topological Properties of Dirac Semimetal Films by Asymmetric Charge Transfer.

    PubMed

    Villanova, John W; Barnes, Edwin; Park, Kyungwha

    2017-02-08

    Dirac semimetals (DSMs) have topologically robust three-dimensional Dirac (doubled Weyl) nodes with Fermi-arc states. In heterostructures involving DSMs, charge transfer occurs at the interfaces, which can be used to probe and control their bulk and surface topological properties through surface-bulk connectivity. Here we demonstrate that despite a band gap in DSM films, asymmetric charge transfer at the surface enables one to accurately identify locations of the Dirac-node projections from gapless band crossings and to examine and engineer properties of the topological Fermi-arc surface states connecting the projections, by simulating adatom-adsorbed DSM films using a first-principles method with an effective model. The positions of the Dirac-node projections are insensitive to charge transfer amount or slab thickness except for extremely thin films. By varying the amount of charge transfer, unique spin textures near the projections and a separation between the Fermi-arc states change, which can be observed by gating without adatoms.

  19. Defect Engineering of Lead-Free Piezoelectrics with High Piezoelectric Properties and Temperature-Stability.

    PubMed

    Feng, Yu; Li, Wei-Li; Xu, Dan; Qiao, Yu-Long; Yu, Yang; Zhao, Yu; Fei, Wei-Dong

    2016-04-13

    The high piezoelectricity of ABO3-type lead-free piezoelectric materials can be achieved with the help of either morphotropic phase boundary (MPB) or polymorphic phase transition (PPT). Here, we propose a new defect engineering route to the excellent piezoelectric properties, in which doped smaller acceptor and donor ions substituting bivalent A-sites are utilized to bring local lattice distortion and lower symmetry. A concrete paradigm is presented, (Li-Al) codoped BaTiO3 perovskite, that exhibits a largely thermo-stable piezoelectric constant (>300 pC/N) and huge mechanical quality factor (>2000). A systematic analysis including theoretical analysis and simulation results indicates that the Li(+) and Al(3+) ions are inclined to occupy the neighboring A-sites in the lattice and constitute a defect dipole (ionic pairs). The defect dipoles possess a kind of dipole moment which tends to align directionally after thermo-electric treatment. A mechanism related to the defect symmetry principle, phase transition, and defect migration is proposed to explain the outstanding piezoelectric properties. The present study opens a new development window for excellent piezoelectricity and provides a promising route to the potential utilization of lead-free piezoelectrics in high power applications.

  20. Chemical and engineering properties of fired bricks containing 50 weight percent of class F fly ash

    USGS Publications Warehouse

    Chou, I.-Ming; Patel, V.; Laird, C.J.; Ho, K.K.

    2001-01-01

    The generation of fly ash during coal combustion represents a considerable solid waste disposal problem in the state of Illinois and nationwide. In fact, the majority of the three million tons of fly ash produced from burning Illinois bituminous coals is disposed of in landfills. The purpose of this study was to obtain a preliminary assessment of the technical feasibility of mitigating this solid waste problem by making fired bricks with the large volume of fly ash generated from burning Illinois coals. Test bricks were produced by the extrusion method with increasing amounts (20-50% by weight) of fly ash as a replacement for conventional raw materials. The chemical characteristics and engineering properties of the test bricks produced with and without 50 wt% of fly ash substitutions were analyzed and compared. The properties of the test bricks containing fly ash were at least comparable to, if not better than, those of standard test bricks made without fly ash and met the commercial specifications for fired bricks. The positive results of this study suggest that further study on test bricks with fly ash substitutions of greater than 50wt% is warranted. Successful results could have an important impact in reducing the waste disposal problem related to class F fly ash while providing the brick industry with a new low cost raw material. Copyright ?? 2001 Taylor & Francis.

  1. Shape Engineered InAs Quantum Dots with Stabilized Electronic Properties

    NASA Astrophysics Data System (ADS)

    Tokranov, Vadim E.; Yakimov, Michael; Katsnelson, Alex; Lamberti, Matthew; Oktyabrsky, Serge

    2003-07-01

    We have studied the influence of overgrowth procedure and a few monolayer-thick AlAs capping layers on the properties of self-assembled InAs quantum dots (QDs) using transmission electron microscopy (TEM), scanning electron microscopy, and photoluminescence (PL). PL spectroscopy was used to study and optimize optical properties of the QDs by shape engineering (QD truncation) through adjustment of the thickness of overlayers and temperature of the subsequent heating. QDs with 6 nm-thick overlayer with heating step at 560°C was found to have the highest PL intensity at room temperature and the lowest FWHM, 29 meV. Ground state energy of the truncated QDs is very stable against variations of growth parameters. TEM measurements show that the capping AlAs layer covers the QDs entirely even though the dots are truncated by the heating step. 1.22 μm edge-emitting laser with triple-layer truncated QD gain medium demonstrated room temperature minimum threshold current density, 56 A/cm2, and high saturated modal gain, 16 cm-1. Extremely high characteristic temperature, To = 304 K in the 20 - 60°C interval, and maximum lasing temperature of 219°C were measured for this laser diode.

  2. Integrating-Sphere Measurements for Determining Optical Properties of Tissue-Engineered Oral Mucosa

    NASA Astrophysics Data System (ADS)

    Ionescu, A. M.; Cardona, J. C.; Garzón, I.; Oliveira, A. C.; Ghinea, R.; Alaminos, M.; Pérez, M. M.

    2015-02-01

    Surgical procedures carried out in the oral and maxillofacial region can result in large tissue defects. Accounting for the shortage of oral mucosa to replace the excised tissues, different models of an organotypic substitute of the oral mucosa generated by tissue engineering have recently been proposed. In this work, the propagation of light radiation through artificial human oral mucosa substitutes based on fibrin-agarose scaffolds (fibrin, fibrin-0.1% agarose, fibrin-0.2%agarose) is investigated, and their optical properties are determined using the inverse adding-doubling (IAD) method based on integrating-sphere measurements. Similar values for the absorption and scattering coefficients between the fibrin and fibrin-0.1% agarose bioengineered tissues and the native oral mucosa were found. These results suggest the adequacy of these biomaterials for potential clinical use in human oral mucosa applications. These optical properties represent useful references and data for applications requiring the knowledge of the light transport through this type of tissues, applications used in clinical practice. It also provides a new method of information analysis for the quality control of the development of the artificial nanostructured oral mucosa substitutes and its comparison with native oral mucosa tissues.

  3. Particle Engineering of Excipients for Direct Compression: Understanding the Role of Material Properties.

    PubMed

    Mangal, Sharad; Meiser, Felix; Morton, David; Larson, Ian

    2015-01-01

    Tablets represent the preferred and most commonly dispensed pharmaceutical dosage form for administering active pharmaceutical ingredients (APIs). Minimizing the cost of goods and improving manufacturing output efficiency has motivated companies to use direct compression as a preferred method of tablet manufacturing. Excipients dictate the success of direct compression, notably by optimizing powder formulation compactability and flow, thus there has been a surge in creating excipients specifically designed to meet these needs for direct compression. Greater scientific understanding of tablet manufacturing coupled with effective application of the principles of material science and particle engineering has resulted in a number of improved direct compression excipients. Despite this, significant practical disadvantages of direct compression remain relative to granulation, and this is partly due to the limitations of direct compression excipients. For instance, in formulating high-dose APIs, a much higher level of excipient is required relative to wet or dry granulation and so tablets are much bigger. Creating excipients to enable direct compression of high-dose APIs requires the knowledge of the relationship between fundamental material properties and excipient functionalities. In this paper, we review the current understanding of the relationship between fundamental material properties and excipient functionality for direct compression.

  4. The National Shipbuilding Research Program. Proceedings of the REAPS Technical Symposium. Paper No. 2: The AUTOFIT CAD/CAM System for Piping Engineering: Operational Experience and Development Status

    DTIC Science & Technology

    1981-09-01

    INNOVATION MARINE INDUSTRY STANDARDS WELDING INDUSTRIAL ENGINEERING EDUCATION AND TRAINING THE NATIONAL SHIPBUILDING RESEARCH PROGRAM September 1981 NSRP 0008...Proceedings of the REAPS Technical Symposium Paper No. 2: The AUTOFIT CAD/CAM System for Piping Engineering: Operational Experience and... Piping Engineering: Operational Experience and Development Status 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d

  5. Giving back or giving up: Native American student experiences in science and engineering.

    PubMed

    Smith, Jessi L; Cech, Erin; Metz, Anneke; Huntoon, Meghan; Moyer, Christina

    2014-07-01

    Native Americans are underrepresented in science, technology, engineering, and math (STEM) careers. We examine communal goal incongruence-the mismatch between students' emphasis on communal work goals and the noncommunal culture of STEM-as a possible factor in this underrepresentation. First, we surveyed 80 Native American STEM freshmen and found they more highly endorsed communal goals than individualistic work goals. Next, we surveyed 96 Native American and White American students in STEM and non-STEM majors and confirmed that both Native American men and women in STEM highly endorsed communal goals. In a third study, we conducted a follow-up survey and in-depth interviews with a subset of Native American STEM students in their second semester to assess their experiences of belonging uncertainty, intrinsic motivation, persistence intentions, and perceived performance in STEM as a function of their initial communal work goals. Results demonstrate the prominence of communal goals among incoming Native American freshman (especially compared with White male STEM majors) and the connection between communal goals and feelings of belonging uncertainty, low motivation, and perceived poor performance 1 semester later. The interview data illustrate that these issues are particularly salient for students raised within tribal communities, and that a communal goal orientation is not just a vague desire to "help others," but a commitment to helping their tribal communities. The interviews also highlight the importance of student support programs for fostering feelings of belonging. We end by discussing implications for interventions and institutional changes that may promote Native American student retention in STEM.

  6. Validation of scaffold design optimization in bone tissue engineering: finite element modeling versus designed experiments.

    PubMed

    Uth, Nicholas; Mueller, Jens; Smucker, Byran; Yousefi, Azizeh-Mitra

    2017-02-21

    This study reports the development of biological/synthetic scaffolds for bone tissue engineering (TE) via 3D bioplotting. These scaffolds were composed of poly(L-lactic-co-glycolic acid) (PLGA), type I collagen, and nano-hydroxyapatite (nHA) in an attempt to mimic the extracellular matrix of bone. The solvent used for processing the scaffolds was 1,1,1,3,3,3-hexafluoro-2-propanol. The produced scaffolds were characterized by scanning electron microscopy, microcomputed tomography, thermogravimetric analysis, and unconfined compression test. This study also sought to validate the use of finite-element optimization in COMSOL Multiphysics for scaffold design. Scaffold topology was simplified to three factors: nHA content, strand diameter, and strand spacing. These factors affect the ability of the scaffold to bear mechanical loads and how porous the structure can be. Twenty four scaffolds were constructed according to an I-optimal, split-plot designed experiment (DE) in order to generate experimental models of the factor-response relationships. Within the design region, the DE and COMSOL models agreed in their recommended optimal nHA (30%) and strand diameter (460 μm). However, the two methods disagreed by more than 30% in strand spacing (908 μm for DE; 601 μm for COMSOL). Seven scaffolds were 3D-bioplotted to validate the predictions of DE and COMSOL models (4.5-9.9 MPa measured moduli). The predictions for these scaffolds showed relative agreement for scaffold porosity (mean absolute percentage error of 4% for DE and 13% for COMSOL), but were substantially poorer for scaffold modulus (51% for DE; 21% for COMSOL), partly due to some simplifying assumptions made by the models. Expanding the design region in future experiments (e.g., higher nHA content and strand diameter), developing an efficient solvent evaporation method, and exerting a greater control over layer overlap could allow developing PLGA-nHA-collagen scaffolds to meet the mechanical requirements for

  7. Extruded collagen fibres for tissue engineering applications: effect of crosslinking method on mechanical and biological properties.

    PubMed

    Enea, Davide; Henson, Frances; Kew, Simon; Wardale, John; Getgood, Alan; Brooks, Roger; Rushton, Neil

    2011-06-01

    Reconstituted collagen fibres are promising candidates for tendon and ligament tissue regeneration. The crosslinking procedure determines the fibres' mechanical properties, degradation rate, and cell-fibre interactions. We aimed to compare mechanical and biological properties of collagen fibres resulting from two different types of crosslinking chemistry based on 1-ethyl-3-(3-dimethyllaminopropyl)carbodiimide (EDC). Fibres were crosslinked with either EDC or with EDC and ethylene-glycol-diglycidyl-ether (EDC/EGDE). Single fibres were mechanically tested to failure and bundles of fibres were seeded with tendon fibroblasts (TFs) and cell attachment and proliferation were determined over 14 days in culture. Collagen type I and tenascin-C production were assessed by immunohistochemistry and dot-blotting. EDC chemistry resulted in fibres with average mechanical properties but the highest cell proliferation rate and matrix protein production. EDC/EGDE chemistry resulted in fibres with improved mechanical properties but with a lower biocompatibility profile. Both chemistries may provide useful structures for scaffolding regeneration of tendon and ligament tissue and will be evaluated for in vivo tendon regeneration in future experiments.

  8. Engineering excitonic properties and valley polarization in transition metal dichalcogenide monolayers

    NASA Astrophysics Data System (ADS)

    Urbaszek, Bernhard

    Binary Transition metal dichalcogenide (TMDC) monolayer (ML) materials MoS2, MoSe2, WSe2, WS2 and MoTe2 share common properties such as a direct optical bandgap, Spin-Orbit splittings of hundreds of meV and coupled spin-valley states. Optical absorption and emission are dominated by robust excitons, whose resonances also strongly influence Raman scattering amplitudes and second harmonic generation efficiency. Important differences in opto-electronic properties between these materials depend on whether the exciton ground state is optically bright or dark. This order will depend on the conduction band Spin-Orbit splitting and the electron-hole Coulomb interaction and will have strong influence on the light emission yield of the TMDC MLs. In this talk we discuss Spin-Orbit engineering in Mo(1-x)W(x)Se2 alloy monolayers. We probe the impact of the tuning of the conduction band Spin-Orbit spin splitting on the bright versus dark exciton population. For MoSe2 monolayers the PL intensity decreases as a function of temperature by an order of magnitude (T=4-300 K), whereas for WSe2 we measure surprisingly an order of magnitude increase. The ternary material shows a trend between these two extreme behaviors. In addition we show a non-linear increase of the optically generated valley polarization as a function of tungsten (W) concentration. Tuning the optical properties in applied external fields will be discussed. We acknowledge funding from ERC Grant No 306719 and ANR MoS2ValleyControl.

  9. Mechanical properties and in vitro behavior of nanofiber-hydrogel composites for tissue engineering applications

    NASA Astrophysics Data System (ADS)

    Kai, Dan; Prabhakaran, Molamma P.; Stahl, Benjamin; Eblenkamp, Markus; Wintermantel, Erich; Ramakrishna, Seeram

    2012-03-01

    Hydrogel-based biomaterial systems have great potential for tissue reconstruction by serving as temporary scaffolds and cell delivery vehicles for tissue engineering (TE). Hydrogels have poor mechanical properties and their rapid degradation limits the development and application of hydrogels in TE. In this study, nanofiber reinforced composite hydrogels were fabricated by incorporating electrospun poly(ɛ-caprolactone) (PCL)/gelatin ‘blend’ or ‘coaxial’ nanofibers into gelatin hydrogels. The morphological, mechanical, swelling and biodegradation properties of the nanocomposite hydrogels were evaluated and the results indicated that the moduli and compressive strengths of the nanofiber reinforced hydrogels were remarkably higher than those of pure gelatin hydrogels. By increasing the amount of incorporated nanofibers into the hydrogel, the Young’s modulus of the composite hydrogels increased from 3.29 ± 1.02 kPa to 20.30 ± 1.79 kPa, while the strain at break decreased from 66.0 ± 1.1% to 52.0 ± 3.0%. Compared to composite hydrogels with coaxial nanofibers, those with blend nanofibers showed higher compressive strength and strain at break, but with lower modulus and energy dissipation properties. Biocompatibility evaluations of the nanofiber reinforced hydrogels were carried out using bone marrow mesenchymal stem cells (BM-MSCs) by cell proliferation assay and immunostaining analysis. The nanocomposite hydrogel with 25 mg ml-1 PCL/gelatin ‘blend’ nanofibers (PGB25) was found to enhance cell proliferation, indicating that the ‘nanocomposite hydrogels’ might provide the necessary mechanical support and could be promising cell delivery systems for tissue regeneration.

  10. Engineering and functional properties of biodegradable pellets developed from various agro-industrial wastes using extrusion technology.

    PubMed

    Jan, Kulsum; Riar, C S; Saxena, D C

    2015-12-01

    Different agro-industrial wastes were mixed with different plasticizers and extruded to form the pellets to be used further for development of biodegradable molded pots. Bulk density and macro-porosity are the important engineering properties used to determine the functional characteristics of the biodegradable pellets viz., expansion volume, water solubility, product colour, flowability and compactness. Significant differences in the functional properties of pellets with varying bulk densities (loose and tapped) and macro-porosities (loose, tapped) were observed. The observed mean bulk density of biodegradable pellets made from different formulations ranged between 0.213 and 0.560 g/ml for loose fill conditions and 0.248 to 0.604 g/ml for tapped fill conditions. Biodegradable pellets bear a good compaction for both loose and tapped fill methods. The mean macro-porosity of biodegradable pellets ranged between 1.19 and 54.48 % for loose fill condition and 0.29 to 53.35 % for tapped fill condition. Hausner ratio (HR) for biodegradable pellets varied from 1.026 to 1.328, indicating a good flowability of biodegradable pellets. Pearson's correlation between engineering properties and functional properties of biodegradable pellets revealed that from engineering properties functional properties can be predicted.

  11. Identifying the changes of geo-engineering properties of dunites due to weathering utilizing electrical resistivity tomography (ERT)

    NASA Astrophysics Data System (ADS)

    Ündül, Ömer; Tuğrul, Atiye; Özyalın, Şenol; Halil Zarif, İ.

    2015-04-01

    Weathering phenomena have an important role in many construction facilities with varying depths and grades. Due to the anisotropic and heterogeneous nature of weathering profiles of some rocks, uncertainities exist in determining the geo-engineering properties. Geo-electrical studies have been utilized to overcome such uncertainities for various subsurface conditions including the determination of boundaries between weathered and unweathered parts of different rock types. In this study, the electrical resistivity tomography (ERT) results were correlated with conventional methods in determining the effects of weathering on the geo-engineering properties of dunites. During the research, weathering grades were determined by field studies including discontinuity spacings, aperture and properties of fill materials. The detailed petrographical studies, determination of petrophysical properties (e.g. water absorption and effective porosity) and mechanical properties (e.g. unconfined compressive strength (UCS)) constitute the laboratory studies. ERT studies were carried out in a row of sixty electrodes with electrode spacings of 0.5 m utilizing a Wenner-Schlumberger configuration. According to the comparison of the inversion model sections with the weathering profiles obtained by field and laboratory studies it is concluded that the use of ERT with a Wenner-Schlumberger configuration supplies comparable data for wider subsurface areas from the view of weathering and its effect on geo-engineering properties of dunites. In addition, ERT techniques are very useful where conventional techniques are inadequate in determining the full weathering profile.

  12. A linear control design structure to maintain loop properties during limit operation in a multi-nozzle turbofan engine

    NASA Technical Reports Server (NTRS)

    Mattern, Duane; Ouzts, Peter

    1991-01-01

    The implementation of multi-variable control systems on turbofan engines requires the use of limit protection to maintain safe engine operation. Since a turbofan engine typically encounters limits during transient operation, the use of a limit protection scheme that modifies the feedback loop may void the desired 'guarantees' associated with linear multi-variable control design methods, necessitating considerable simulation to validate the control with limit protection. An alternative control design structure is proposed that maintains the desired linear feedback properties when certain safety limits are encountered by moving the limit protection scheme outside of the feedback loop. This proposed structure is compared to a structure with a limit protection scheme that modifies the feedback loop properties. The two design structures are compared using both linear and nonlinear simulations. The evaluation emphasizes responses where the fan surge margin limit is encountered.

  13. A linear control design structure to maintain loop properties during limit operation in a multi-nozzle turbofan engine

    NASA Technical Reports Server (NTRS)

    Mattern, Duane; Ouzts, Peter

    1991-01-01

    The implementation of multi-variable control systems on turbofan engines requires the use of limit protection to maintain safe engine operation. Since a turbofan engine typically encounters limits during transient operation, the use of a limit protection scheme that modifies the feedback loop may void the desired 'guarantees' associated with linear multi-variable control design methods, necessitating considerable simulation to validate the control with limited protection. An alternative control design structure is proposed that maintains the desired linear feedback properties when certain safety limits are encountered by moving the limit protection scheme outside the feedback loop. This proposed structure is compared to a structure with a limit protection scheme that modifies the feedback loop properties. The two design structures are compared using both linear and nonlinear simulations. The evaluation emphasizes responses where the fan surge margin limit is encountered.

  14. Multi-component nanofibrous scaffolds with tunable properties for bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Jose, Moncy V.

    Bone is a highly complex tissue which is an integral part of vertebrates and hence any damage has a major negative effect on the quality of life. Tissue engineering is regarded as an ideal route to resolve the issues related to the scarcity of tissue and organ for transplantation. Apart from cell line and growth factors, the choice of materials and fabrication technique for scaffold are equally important. The goal of this work was to develop a multi-component nanofibrous scaffold based on a synthetic polymer (poly(lactic-co-glycolide) (PLGA)), a biopolymer (collagen) and a biomineral (nano-hydroxyapatite (nano-HA)) by electrospinning technique, which mimics the nanoscopic, chemical, and anisotropic features of bone. Preliminary studies involved fabrication of nanocomposite scaffolds based on PLGA and nano-HA. Morphological and mechanical characterizations revealed that at low concentrations, nano-HA acted as reinforcements, whereas at higher concentrations the presence of aggregation was detrimental to the scaffold. Hydrolytic degradation studies revealed the scaffold had a little mass loss and the mechanical property was maintained for a period of 6 weeks. This study was followed by evaluation of a blend system based on PLGA and collagen. Collagen addition provides hydrophilicity and the necessary cell binding sites in PLGA. The structural characterization revealed that the blend had limited interactions between the two components. The mechanical characterization revealed that with increasing collagen concentration, there was a decline in mechanical properties. However, crosslinking of the blend system, with carbodiimide (EDC) resulted in improving the mechanical properties of the scaffolds. A multi-component system was developed by adding different concentrations of nano-HA to a fixed PLGA/collagen blend composition (80/20). Morphological and mechanical characterizations revealed properties similar to the PLGA/HA system. Cyto-compatibility studies revealed

  15. Light-Duty Drive Cycle Simulations of Diesel Engine-Out Exhaust Properties for an RCCI-Enabled Vehicle

    SciTech Connect

    Gao, Zhiming; Curran, Scott; Daw, C Stuart; Wagner, Robert M

    2013-01-01

    In-cylinder blending of gasoline and diesel fuels to achieve low-temperature reactivity controlled compression ignition (RCCI) can reduce NOx and PM emissions while maintaining or improving brake thermal efficiency compared to conventional diesel combustion (CDC). Moreover, the dual-fueling RCCI is able to achieve these benefits by tailoring combustion reactivity over a wider range of engine operation than is possible with a single fuel. However, the currently demonstrated range of stable RCCI combustion just covers a portion of the engine speed-load range required in several light-duty drive cycles. This means that engines must switch from RCCI to CDC when speed and load fall outside of the stable RCCI range. In this study we investigated the impact of RCCI as it has recently been demonstrated on practical engine-out exhaust temperature and emissions by simulating a multi-mode RCCI-enabled vehicle operating over two urban and two highway driving cycles. To implement our simulations, we employed experimental engine maps for a multi-mode RCCI/CDC engine combined with a standard mid-size, automatic transmission, passenger vehicle in the Autonomie vehicle simulation platform. Our results include both detailed transient and cycle-averaged engine exhaust temperature and emissions for each case, and we note the potential implications of the modified exhaust properties on catalytic emissions control and utilization of waste heat recovery on future RCCI-enabled vehicles.

  16. Surface zone articular chondrocytes modulate the bulk and surface mechanical properties of the tissue-engineered cartilage.

    PubMed

    Peng, Gordon; McNary, Sean M; Athanasiou, Kyriacos A; Reddi, A Hari

    2014-12-01

    The central hypothesis of functional tissue engineering is that an engineered construct can serve as a viable replacement tissue in vivo by replicating the structure and function of native tissue. In the case of articular cartilage, this requires the reproduction of the bulk mechanical and surface lubrication properties of native hyaline cartilage. Cartilage tissue engineering has primarily focused on achieving the bulk mechanical properties of native cartilage such as the compressive aggregate modulus and tensile strength. A scaffold-free self-assembling process has been developed that produces engineered cartilage with compressive properties approaching native tissue levels. Thus, the next step in this process is to begin addressing the friction coefficient and wear properties of these engineered constructs. The superficial zone protein (SZP), also known as lubricin or PRG4, is a boundary mode lubricant that is synthesized by surface zone (SZ) articular chondrocytes. Under conditions of high loading and low sliding speeds, SZP reduces friction and wear at the articular surface. The objective of this investigation was to determine whether increasing the proportion of SZ chondrocytes in cartilage constructs, in the absence of external stimuli such as growth factors and mechanical loading, would enhance the secretion of SZP and improve their frictional properties. In this study, cartilage constructs were engineered through a self-assembling process with varying ratios of SZ and middle zone (MZ) chondrocytes (SZ:MZ): 0:100, 25:75, 50:50, 75:25, and 100:0. Constructs containing different ratios of SZ and MZ chondrocytes did not significantly differ in the glycosaminoglycan composition or compressive aggregate modulus. In contrast, tensile properties and collagen content were enhanced in nearly all constructs containing greater amounts of SZ chondrocytes. Increasing the proportion of SZ chondrocytes had the hypothesized effect of improving the synthesis and secretion

  17. Fe-SAPONITE and Chlorite Growth on Stainless Steel in Hydrothermal Engineered Barrier Experiments

    NASA Astrophysics Data System (ADS)

    Cheshire, M. C.; Caporuscio, F. A.; McCarney, M.

    2012-12-01

    The United States recently has initiated the Used Fuel Disposition campaign to evaluate various generic geological repositories for the disposal of high-level, spent nuclear fuel within environments ranging from hard-rock, salt/clay, to deep borehole settings. Previous work describing Engineered Barrier Systems (EBS) for repositories focused on low temperature and pressure conditions. The focus of this experimental work is to characterize the stability and alteration of a bentonite-based EBS with different waste container materials in brine at higher heat loads and pressures. All experiments were run at ~150 bar and 125 to 300 C for ~1 month. Unprocessed bentonite from Colony, Wyoming was used in the experiments as the clay buffer material. The redox conditions for each system were buffered along the magnetite-iron oxygen fugacity univariant curve using Fe3O4 and Feo filings. A K-Na-Ca-Cl-based salt solution was chosen to replicate deep groundwater compositions. The experimental mixtures were 1) salt solution-clay; 2) salt solution -clay-304 stainless steel; and 3) salt solution -clay-316 stainless steel with a water/bentonite ratio of ~9. Mineralogy and aqueous geochemistry of each experiment was evaluated to monitor the reactions that took place. No smectite illitization was observed in these reactions. However, it appears that K-smectite was produced, possibly providing a precursor to illitization. It is unclear whether reaction times were sufficient for bentonite illitization at 212 and 300 C or whether conditions conducive to illite formation were obtained. The more notable clay mineral reactions occurred at the stainless steel surfaces. Authigenic chlorite and Fe-saponite grew with their basal planes near perpendicular to the steel plate, forming a 10 - 40 μm thick 'corrosion' layer. Partial dissolution of the steel plates was the likely iron source for chlorite/saponite formation; however, dissolution of the Feo/Fe3O4 may also have acted as an iron source

  18. Inductive knowledge acquisition experience with commercial tools for space shuttle main engine testing

    NASA Technical Reports Server (NTRS)

    Modesitt, Kenneth L.

    1990-01-01

    Since 1984, an effort has been underway at Rocketdyne, manufacturer of the Space Shuttle Main Engine (SSME), to automate much of the analysis procedure conducted after engine test firings. Previously published articles at national and international conferences have contained the context of and justification for this effort. Here, progress is reported in building the full system, including the extensions of integrating large databases with the system, known as Scotty. Inductive knowledge acquisition has proven itself to be a key factor in the success of Scotty. The combination of a powerful inductive expert system building tool (ExTran), a relational data base management system (Reliance), and software engineering principles and Computer-Assisted Software Engineering (CASE) tools makes for a practical, useful and state-of-the-art application of an expert system.

  19. Exploratory Experiments in the Tribological Behavior of Engineering Surfaces with Nano-Coating Using a Tribo-Rheometer

    DTIC Science & Technology

    2008-05-30

    characteristics of nano -coated engineering surfaces. In addition, the effect of micro -particles in the rheology of these systems was investigated. Depends...due to the protection provided by the nano -structures. In addition we performed the first set of rheological experiments on slurry of micro ...range of temperatures and harsh conditions. Having access to the state-of-the-art facilities in micro - and nano -fabrication at UCLA allows us to create a

  20. Participant outcomes, perceptions, and experiences in the Internationally Educated Engineers Qualification Program, University of Manitoba: An exploratory study

    NASA Astrophysics Data System (ADS)

    Friesen, Marcia R.

    Immigration, economic, and regulatory trends in Canada have challenged all professions to examine the processes by which immigrant professionals (international graduates) achieve professional licensure and meaningful employment in Canada. The Internationally Educated Engineers Qualification Program (IEEQ) at the University of Manitoba was developed as an alternate pathway to integrate international engineering graduates into the engineering profession in Manitoba. However, universities have the neither mandate nor the historical practice to facilitate licensure for immigrant professionals and, thus, the knowledge base for program development and delivery is predominantly experiential. This study was developed to address the void in the knowledge base and support the program's ongoing development by conducting a critical, exploratory, participant-oriented evaluation of the IEEQ Program for both formative and summative purposes. The research questions focussed on how the IEEQ participants perceived and described their experiences in the IEEQ Program, and how the participants' outcomes in the IEEQ Program compared to international engineering graduates pursuing other licensing pathways. The study was built on an interpretivist theoretical approach that supported a primarily qualitative methodology with selected quantitative elements. Data collection was grounded in focus group interviews, written questionnaires, student reports, and program records for data collection, with inductive data analysis for qualitative data and descriptive statistics for quantitative data. The findings yielded rich understandings of participants' experiences in the IEEQ Program, their outcomes relative to international engineering graduates (IEGs) pursuing other licensing pathways, and their perceptions of their own adaptation to the Canadian engineering profession. Specifically, the study suggests that foreign credentials recognition processes have tended to focus on the recognition and

  1. Heparinized PLLA/PLCL nanofibrous scaffold for potential engineering of small-diameter blood vessel: tunable elasticity and anticoagulation property.

    PubMed

    Wang, Weizhong; Hu, Jinwei; He, Chuanglong; Nie, Wei; Feng, Wei; Qiu, Kexin; Zhou, Xiaojun; Gao, Yu; Wang, Guoqing

    2015-05-01

    The success of tissue engineered vascular grafts depends greatly on the synthetic tubular scaffold, which can mimic the architecture, mechanical, and anticoagulation properties of native blood vessels. In this study, small-diameter tubular scaffolds were fabricated with different weight ratios of poly(l-lactic acid) (PLLA) and poly(l-lactide-co-ɛ-caprolactone) (PLCL) by means of thermally induced phase separation technique. To improve the anticoagulation property of materials, heparin was covalently linked to the tubular scaffolds by N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide coupling chemistry. The as-prepared PLLA/PLCL scaffolds retained microporous nanofibrous structure as observed in the neat PLLA scaffolds, and their structural and mechanical properties can be fine-tuned by changing the ratio of two components. The scaffold containing 60% PLCL content was found to be the most promising scaffold for engineering small-diameter blood vessel in terms of elastic properties and structural integrity. The heparinized scaffolds showed higher hydrophilicity, lower protein adsorption ability, and better in vitro anticoagulation property than their untreated counterparts. Pig iliac endothelial cells seeded on the heparinized scaffold showed good cellular attachment, spreading, proliferation, and phenotypic maintenance. Furthermore, the heparinized scaffolds exhibited neovascularization after subcutaneous implantation into the New Zealand white rabbits for 1 and 2 months. Taken together, the heparinized PLLA/PLCL nanofibrous scaffolds have the great potential for vascular tissue engineering application.

  2. The E and B EXperiment: Implementation and Analysis of the 2009 Engineering Flight

    NASA Astrophysics Data System (ADS)

    Milligan, Michael Bryce

    The E and B EXperiment (EBEX) is a balloon-borne telescope designed to map the polarization of the cosmic microwave background (CMB) and emission from galactic dust at millimeter wavelengths from 150 to 410 GHz. The primary science objectives of EBEX are to: detect or constrain the primordial B-mode polarization of the CMB predicted by inflationary cosmology; measure the CMB B-mode signal induced by gravitational lensing; and characterize the polarized thermal emission from interstellar dust. EBEX will observe a 420 square degree patch of the sky at high galactic latitude with a telescope and camera that provide an 8 arcminute beam at three observing bands (150, 250, and 410 GHz) and a 6.2 degree diffraction limited field of view to two large-format bolometer array focal planes. Polarimetry is achieved via a continuously rotating half-wave plate (HWP), and the optical system is designed from the ground up for control of sidelobe response and polarization systematic errors. EBEX is intended to execute fly or more Antarctic long duration balloon campaigns. In June 2009 EBEX completed a North American engineering flight launched from NASA's Columbia Scientific Ballooning Facility (CSBF) in Ft. Sumner, NM and operated in the stratosphere above 30 km altitude for ˜10 hours. During flight EBEX must be largely autonomous as it conducts pointed, scheduled observations; tunes and operates 1432 TES bolometers via 28 embedded Digital frequency-domain multiplexing (DfMux) computers; logs over 3 GiB/hour of science and housekeeping data to onboard redundant disk storage arrays; manages and dispatches jobs over a fault-tolerant onboard Ethernet network; and feeds a complex real-time data processing infrastructure on the ground via satellite and line-of-sight (LOS) downlinks. In this thesis we review the EBEX instrument, present the optical design and the computational architecture for in-flight control and data handling, and the quick-look software stack. Finally we describe

  3. Premixed ignition behavior of alternative diesel fuel-relevant compounds in a motored engine experiment

    SciTech Connect

    Szybist, James P.; Boehman, Andre L.; Haworth, Daniel C.; Koga, Hibiki

    2007-04-15

    A motored engine study using premixed charges of fuel and air at a wide range of diesel-relevant equivalence ratios was performed to investigate autoignition differences among surrogates for conventional diesel fuel, gas-to-liquid (GTL) diesel fuel, and biodiesel, as well as n-heptane. Experiments were performed by delivering a premixed charge of vaporized fuel and air and increasing the compression ratio in a stepwise manner to increase the extent of reaction while monitoring the exhaust composition via Fourier transform infrared (FTIR) spectrometry and collecting condensable exhaust gas for subsequent gas chromatography/mass spectrometry (GC/MS) analysis. Each fuel demonstrated a two-stage ignition process, with a low-temperature heat release (LTHR) event followed by the main combustion, or high-temperature heat release (HTHR). Among the three diesel-relevant fuels, the magnitude of LTHR was highest for GTL diesel, followed by methyl decanoate, and conventional diesel fuel last. FTIR analysis of the exhaust for n-heptane, the conventional diesel surrogate, and the GTL diesel surrogate revealed that LTHR produces high concentrations of aldehydes and CO while producing only negligible amounts of CO{sub 2}. Methyl decanoate differed from the other two-stage ignition fuels only in that there were significant amounts of CO{sub 2} produced during LTHR; this was the result of decarboxylation of the ester group, not the result of oxidation. GC/MS analysis of LTHR exhaust condensate for n-heptane revealed high concentrations of 2,5-heptanedione, a di-ketone that can be closely tied to species in existing autoignition models for n-heptane. GC/MS analysis of the LTHR condensate for conventional diesel fuel and GTL diesel fuel revealed a series of high molecular weight aldehydes and ketones, which were expected, as well as a series of organic acids, which are not commonly reported as products of combustion. The GC/MS analysis of the methyl decanoate exhaust condensate

  4. Minority University System Engineering: A Small Satellite Design Experience Held at the Jet Propulsion Laboratory During the Summer of 1996

    NASA Technical Reports Server (NTRS)

    Ordaz, Miguel Angel

    1997-01-01

    The University of Texas at El Paso (UTEP) in conjunction with the Jet Propulsion Laboratory (JPL), North Carolina A&T and California State University of Los Angeles participated during the summer of 1996 in a prototype program known as Minority University Systems Engineering (MUSE). The program consisted of a ten week internship at JPL for students and professors of the three universities. The purpose of MUSE as set forth in the MUSE program review August 5, 1996 was for the participants to gain experience in the following areas: 1) Gain experience in a multi-disciplinary project; 2) Gain experience working in a culturally diverse atmosphere; 3) Provide field experience for students to reinforce book learning; and 4) Streamline the design process in two areas: make it more financially feasible; and make it faster.

  5. Framework for Small-Scale Experiments in Software Engineering: Guidance and Control Software Project: Software Engineering Case Study

    NASA Technical Reports Server (NTRS)

    Hayhurst, Kelly J.

    1998-01-01

    Software is becoming increasingly significant in today's critical avionics systems. To achieve safe, reliable software, government regulatory agencies such as the Federal Aviation Administration (FAA) and the Department of Defense mandate the use of certain software development methods. However, little scientific evidence exists to show a correlation between software development methods and product quality. Given this lack of evidence, a series of experiments has been conducted to understand why and how software fails. The Guidance and Control Software (GCS) project is the latest in this series. The GCS project is a case study of the Requirements and Technical Concepts for Aviation RTCA/DO-178B guidelines, Software Considerations in Airborne Systems and Equipment Certification. All civil transport airframe and equipment vendors are expected to comply with these guidelines in building systems to be certified by the FAA for use in commercial aircraft. For the case study, two implementations of a guidance and control application were developed to comply with the DO-178B guidelines for Level A (critical) software. The development included the requirements, design, coding, verification, configuration management, and quality assurance processes. This paper discusses the details of the GCS project and presents the results of the case study.

  6. Terminal ballistic experiments for the development of turbine engine blade containment technology

    SciTech Connect

    Gogolewski, R.P.; Cunningham, B.J.

    1995-01-25

    The ballistic experiments reported herein were conducted in three sets between October 1993 and November 1994. The first set of experiments examined the ballistic failure of annealed titanium plates. These experiments were performed in a manner consistent with earlier experiments conducted at United Technologies` Pratt and Whitney Division. The second set of experiments examined the ballistic performance of select aluminum and titanium alloys in single-plate and laminate form. In both sets of experiments, the failure modes of the targets were observed and catalogued. The third set of experiments evaluated underlying issues associated with geometric scaling. Blunt .30-and .50-caliber hard steel projectiles impacted on geometrically similar annealed titanium plates.

  7. [Effects of Cultivation Soil Properties on the Transport of Genetically Engineered Microorganism in Huabei Plain].

    PubMed

    Zhang, Jing; Liu, Ping; Liu, Chun; Chen, Xiao-xuan; Zhang, Lei

    2015-12-01

    The transport of genetically engineered microorganism (GEM) in the soil is considered to be the important factor influencing the enhanced bioremediation of polluted soil. The transport of an atrazine-degrading GEM and its influencing factors were investigated in the saturated cultivation soil of Huabei Plain. The results showed that horizontal infiltration was the main mechanism of GEM transport in the saturated cultivation soil. The transport process could be simulated using the filtration model. Soil properties showed significant effects on pore water flow and GEM transport in saturated soil. When particle size, porosity and sand component of the soil increased, the hydraulic conductivity constant increased and filtration coefficient of GEM decreased in saturated soil, indicating the reduced retention of GEM in the soil. An increase in infiltration flow also increased hydraulic conductivity constant in saturated soil and consequently decreased filtration coefficient of GEM. When hydraulic conductivity constants ranged from 5.02 m · d⁻¹ to 6.70 m · d⁻¹ in the saturated soil, the filtration coefficients of GEM varied from 0.105 to 0.274. There was a significantly negative correlation between them.

  8. An Analysis of the Impact of Selected Fuel Thermochemical Properties on Internal Combustion Engine Efficiency

    SciTech Connect

    Szybist, James P; Chakravathy, Kalyana; Daw, C Stuart

    2012-01-01

    In this study we model the effects of 23 different fuels on First and Second Law thermodynamic efficiency of an adiabatic internal combustion engine. First Law efficiency is calculated using lower heating value (LHV) while Second Law efficiency is calculated with exergy, which represents the inherent chemical energy available to produce propulsion. We find that First Law efficiency can deviate by as much as nine percentage points between fuels while Second Law efficiency exhibits a much smaller degree of variability. We also find that First and Second Law efficiency can be nearly the same for some fuels (methane and ethane) but differ substantially for other fuels (hydrogen and ethanol). The differences in First and Second Law efficiency are due to differences in LHV and exergy for a given fuel. In order to explain First Law efficiency differences between fuels as well as the differences between LHV and exergy, we introduce a new term: the molar expansion ratio (MER), defined as the ratio of product moles to reactant moles for complete stoichiometric combustion. We find that the MER is a useful expression for providing a physical explanation for fuel-specific efficiency differences as well as differences between First and Second Law efficiency. First and Second Law efficiency are affected by a number of other fuel-specific thermochemical properties, such as the ratio of specific heat and dissociation of combustion products.

  9. Unexpected property of ectoine synthase and its application for synthesis of the engineered compatible solute ADPC.

    PubMed

    Witt, Elisabeth M H J; Davies, Noel W; Galinski, Erwin A

    2011-07-01

    A new cyclic amino acid was detected in a deletion mutant of the moderately halophilic bacterium Halomonas elongata deficient in ectoine synthesis. Using mass spectroscopy (MS) and nuclear magnetic resonance (NMR) techniques, the substance was identified as 5-amino-3,4-dihydro-2H-pyrrole-2-carboxylate (ADPC). We were able to demonstrate that ADPC is the product of a side reaction of lone ectoine synthase (EC 4.2.1.108), which forms ADPC by cyclic condensation of glutamine. This reaction was shown to be reversible. Subsequently, a number of ectoine derivatives, in particular 4,5-dihydro-2-methylimidazole-4-carboxylate (DHMICA) and homoectoine, were also shown to be cleaved by ectoine synthase, which is classified as a hydro-lyase. This study thus reports for the first time that ectoine synthase accepts more than one substrate and is a reversible enzyme able to catalyze both the intramolecular condensation into and the hydrolytic cleavage of cyclic amino acid derivatives. As ADPC supports growth of bacteria under salt stress conditions and stabilizes enzymes against freeze-thaw denaturation, it displays typical properties of compatible solutes. As ADPC has not yet been described as a natural compound, it is presented here as the first man-made compatible solute created through genetic engineering.

  10. Developing a geologic and engineering properties data base with INGRES. [Yucca Mountain Project

    SciTech Connect

    Krebs-Jespersen, M.L.

    1989-01-01

    The design of a data base for storing diverse geological and site engineering properties data from various sources using the INGRES data base management system has required (1) designing tables for data that are similar but have very different test conditions to be reported, (2) determining what data is necessary to ensure that all records are unique, (3) changing, as necessary, the design of data base tables to accommodate the needs of new data submittals, (4) defining limits to comments and descriptions of test conditions to be stored in the data base, (5) solving problems caused by the limitations of the available field types in INGRES, and (6) designing a tracking system for data submissions to satisfy Project quality assurance requirements. The resulting relational data base design is simple, flexible, and capable of accommodating changes in requirements for data storage and user needs. The INGRES Report Writer utility has proven to be a powerful tool for generating reports because the Report Writer code is easily revised as table structure changes. Separate data storage tables can be joined for report production, and output can be customized for each user.

  11. Enhanced mechanical properties of thermosensitive chitosan hydrogel by silk fibers for cartilage tissue engineering.

    PubMed

    Mirahmadi, Fereshteh; Tafazzoli-Shadpour, Mohammad; Shokrgozar, Mohammad Ali; Bonakdar, Shahin

    2013-12-01

    Articular cartilage has limited repair capability following traumatic injuries and current methods of treatment remain inefficient. Reconstructing cartilage provides a new way for cartilage repair and natural polymers are often used as scaffold because of their biocompatibility and biofunctionality. In this study, we added degummed chopped silk fibers and electrospun silk fibers to the thermosensitive chitosan/glycerophosphate hydrogels to reinforce two hydrogel constructs which were used as scaffold for hyaline cartilage regeneration. The gelation temperature and gelation time of hydrogel were analyzed by the rheometer and vial tilting method. Mechanical characterization was measured by uniaxial compression, indentation and dynamic mechanical analysis assay. Chondrocytes were then harvested from the knee joint of the New Zealand white rabbits and cultured in constructs. The cell proliferation, viability, production of glycosaminoglycans and collagen type II were assessed. The results showed that mechanical properties of the hydrogel were significantly enhanced when a hybrid with two layers of electrospun silk fibers was made. The results of GAG and collagen type II in cell-seeded scaffolds indicate support of the chondrogenic phenotype for chondrocytes with a significant increase in degummed silk fiber-hydrogel composite for GAG content and in two-layer electrospun fiber-hydrogel composite for Col II. It was concluded that these two modified scaffolds could be employed for cartilage tissue engineering.

  12. Mechanical properties of electrospun bilayer fibrous membranes as potential scaffolds for tissue engineering.

    PubMed

    Pu, Juan; Komvopoulos, Kyriakos

    2014-06-01

    Bilayer fibrous membranes of poly(l-lactic acid) (PLLA) were fabricated by electrospinning, using a parallel-disk mandrel configuration that resulted in the sequential deposition of a layer with fibers aligned across the two parallel disks and a layer with randomly oriented fibers, both layers deposited in a single process step. Membrane structure and fiber alignment were characterized by scanning electron microscopy and two-dimensional fast Fourier transform. Because of the intricacies of the generated electric field, bilayer membranes exhibited higher porosity than single-layer membranes consisting of randomly oriented fibers fabricated with a solid-drum collector. However, despite their higher porosity, bilayer membranes demonstrated generally higher elastic modulus, yield strength and toughness than single-layer membranes with random fibers. Bilayer membrane deformation at relatively high strain rates comprised multiple abrupt microfracture events characterized by discontinuous fiber breakage. Bilayer membrane elongation yielded excessive necking of the layer with random fibers and remarkable fiber stretching (on the order of 400%) in the layer with fibers aligned in the stress direction. In addition, fibers in both layers exhibited multiple localized necking, attributed to the nonuniform distribution of crystalline phases in the fibrillar structure. The high membrane porosity, good mechanical properties, and good biocompatibility and biodegradability of PLLA (demonstrated in previous studies) make the present bilayer membranes good scaffold candidates for a wide range of tissue engineering applications.

  13. Models for predicting the mass of lime fruits by some engineering properties.

    PubMed

    Miraei Ashtiani, Seyed-Hassan; Baradaran Motie, Jalal; Emadi, Bagher; Aghkhani, Mohammad-Hosein

    2014-11-01

    Grading fruits based on mass is important in packaging and reduces the waste, also increases the marketing value of agricultural produce. The aim of this study was mass modeling of two major cultivars of Iranian limes based on engineering attributes. Models were classified into three: 1-Single and multiple variable regressions of lime mass and dimensional characteristics. 2-Single and multiple variable regressions of lime mass and projected areas. 3-Single regression of lime mass based on its actual volume and calculated volume assumed as ellipsoid and prolate spheroid shapes. All properties considered in the current study were found to be statistically significant (ρ < 0.01). The results indicated that mass modeling of lime based on minor diameter and first projected area are the most appropriate models in the first and the second classifications, respectively. In third classification, the best model was obtained on the basis of the prolate spheroid volume. It was finally concluded that the suitable grading system of lime mass is based on prolate spheroid volume.

  14. Strong Modulation of Optical Properties in Black Phosphorus through Strain-Engineered Rippling.

    PubMed

    Quereda, Jorge; San-Jose, Pablo; Parente, Vincenzo; Vaquero-Garzon, Luis; Molina-Mendoza, Aday J; Agraït, Nicolás; Rubio-Bollinger, Gabino; Guinea, Francisco; Roldán, Rafael; Castellanos-Gomez, Andres

    2016-05-11

    Controlling the bandgap through local-strain engineering is an exciting avenue for tailoring optoelectronic materials. Two-dimensional crystals are particularly suited for this purpose because they can withstand unprecedented nonhomogeneous deformations before rupture; one can literally bend them and fold them up almost like a piece of paper. Here, we study multilayer black phosphorus sheets subjected to periodic stress to modulate their optoelectronic properties. We find a remarkable shift of the optical absorption band-edge of up to ∼0.7 eV between the regions under tensile and compressive stress, greatly exceeding the strain tunability reported for transition metal dichalcogenides. This observation is supported by theoretical models that also predict that this periodic stress modulation can yield to quantum confinement of carriers at low temperatures. The possibility of generating large strain-induced variations in the local density of charge carriers opens the door for a variety of applications including photovoltaics, quantum optics, and two-dimensional optoelectronic devices.

  15. Nano-composite scaffolds for bone tissue engineering containing silver nanoparticles: preparation, characterization and biological properties.

    PubMed

    Marsich, Eleonora; Bellomo, Francesca; Turco, Gianluca; Travan, Andrea; Donati, Ivan; Paoletti, Sergio

    2013-07-01

    In this study nano-composite scaffolds to be used as bone grafts have been endowed with antibacterial properties owing to the presence of silver nanoparticles. The alginate/hydroxyapatite composite scaffolds were prepared by internal gelation followed by a freeze-drying procedure to obtain a porous structure. The nanoparticles were prepared in presence of a lactose modified-chitosan and this colloidal solution was adsorbed on the scaffolds by exploiting electrostatic interactions. The adsorption and release of the silver from the composite scaffold was measured by ICP-AES and spectrofluorimetry measurements. Micro-computed tomography analysis of the scaffolds showed a homogeneous porous structure with average pore sizes of 341.5 μm and porosity of 80 %. In vitro biological tests (MTS and killing kinetics assays) demonstrated that silver does not affect the ability of the scaffolds to promote osteoblasts proliferation and that at the same time it exerts a strong bactericidal effect against both Gram+ and Gram- bacterial strains. Overall, the combined results indicate that these biocompatible antimicrobial scaffolds possess ideal characteristics for tissue engineering applications.

  16. Secondary materials: Engineering properties, environmental consequences, and social and economic impacts. Final report

    SciTech Connect

    Breslin, V.; Reaven, S.; Schwartz, M.; Swanson, L.; Zweig, M.; Bortman, M.; Schubel, J.

    1993-08-01

    This report investigates two secondary materials, plastic lumber made from mixed plastic waste, and cement blocks and structures made with incinerator ash. Engineering properties, environmental impacts, and energy costs and savings of these secondary materials are compared to standard lumber products and cement blocks. Market capacity and social acceptance of plastic lumber and stabilized ash products are analyzed. These secondary materials apparently have potential markets; however, their economic value is primarily that they will not take up landfill space. For plastic lumber and stabilized incinerator ash products, marine and highway construction seem ideal public works applications. Incinerator ash may be suitable to use in seawalls, jetties, fishing reefs, highway barriers, and roadbed applications. Docks, piers, highway sound barriers, parking stops, and park furniture may all be made from plastic lumber. To encourage public acceptance and improve the market potential of secondary materials, these activities could be beneficial: industry should emphasize developing useful, long-lived products; industry and governments should create product performance criteria; government should provide rigorous testing and demonstration programs; and government and industry should cooperate to improve public outreach and educational programs.

  17. Band structure engineering and thermoelectric properties of charge-compensated filled skutterudites

    DOE PAGES

    Shi, Xiaoya; Yang, Jiong; Wu, Lijun; ...

    2015-10-12

    Thermoelectric properties of semiconductors are intimately related to their electronic band structure, which can be engineered via chemical doping. Dopant Ga in the cage-structured skutterudite Co4Sb12 substitutes Sb sites while occupying the void sites. Combining quantitative scanning transmission electron microscopy and first-principles calculations, we show that Ga dual-site occupancy breaks the symmetry of the Sb-Sb network, splits the deep triply-degenerate conduction bands, and drives them downward to the band edge. The charge-compensating nature of the dual occupancy Ga increases overall filling fraction limit. By imparting this unique band structure feature, and judiciously doping the materials by increasing the Yb content,more » we promote the Fermi level to a point where carriers are in energetic proximity to these features. Increased participation of these heavier bands in electronic transport leads to increased thermopower and effective mass. Further, the localized distortion from Ga/Sb substitution enhances the phonon scattering to reduce the thermal conductivity effectively.« less

  18. Band structure engineering and thermoelectric properties of charge-compensated filled skutterudites

    SciTech Connect

    Shi, Xiaoya; Yang, Jiong; Wu, Lijun; Salvador, James R.; Zhang, Cheng; Villaire, William L.; Haddad, Daad; Yang, Jihui; Zhu, Yimei; Li, Qiang

    2015-10-12

    Thermoelectric properties of semiconductors are intimately related to their electronic band structure, which can be engineered via chemical doping. Dopant Ga in the cage-structured skutterudite Co4Sb12 substitutes Sb sites while occupying the void sites. Combining quantitative scanning transmission electron microscopy and first-principles calculations, we show that Ga dual-site occupancy breaks the symmetry of the Sb-Sb network, splits the deep triply-degenerate conduction bands, and drives them downward to the band edge. The charge-compensating nature of the dual occupancy Ga increases overall filling fraction limit. By imparting this unique band structure feature, and judiciously doping the materials by increasing the Yb content, we promote the Fermi level to a point where carriers are in energetic proximity to these features. Increased participation of these heavier bands in electronic transport leads to increased thermopower and effective mass. Further, the localized distortion from Ga/Sb substitution enhances the phonon scattering to reduce the thermal conductivity effectively.

  19. Silver and Gold Nanostructures: Engineering their Optical Properties for Biomedical Applications.

    NASA Astrophysics Data System (ADS)

    Xia, Younan

    2006-03-01

    We have focused on shape-controlled synthesis of silver and gold nanostructures. While the synthetic methodology mainly involves solution-phase redox chemistry, we have been working diligently to understand the complex physics behind the simple chemistry -- that is, the nucleation and growth mechanisms leading to the formation of nanostructures with a specific shape. Polyol synthesis of silver nanostructures provides a good example to illustrate this concept. We discovered that the shape of silver nanostructures were dictated by both the crystallinity and shape of nanocrystallite seeds, which were, in turn, controlled by factors such as reduction rate, oxidative etching, and surface capping. We also exploited the galvanic replacement reaction between silver and chloroauric acid to transform silver nanocubes into gold nanocages with controlled void size, wall thickness, and wall porosity. We were able to engineer the optical properties of resulting gold nanocages with optical resonance peaks ranging from the blue (400 nm) to the near infrared (1200 nm) simply by controlling the molar ratio of silver to chloroauric acid. Thanks to their exceptionally large scattering and absorption coefficients in the transparent window for soft tissues, this novel class of gold nanostructures has great potential emerging as both a contrast agent for optical imaging in early-stage tumor detection, and a therapeutic agent for photothermal cancer treatment.

  20. Strain-engineered optoelectronic properties of 2D transition metal dichalcogenide lateral heterostructures

    DOE PAGES

    Lee, Jaekwang; Huang, Jingsong; Sumpter, Bobby G.; ...

    2017-02-17

    Compared with their bulk counterparts, 2D materials can sustain much higher elastic strain at which optical quantities such as bandgaps and absorption spectra governing optoelectronic device performance can be modified with relative ease. Using first-principles density functional theory and quasiparticle GW calculations, we demonstrate how uniaxial tensile strain can be utilized to optimize the electronic and optical properties of transition metal dichalcogenide lateral (in-plane) heterostructures such as MoX2/WX2 (X = S, Se, Te). We find that these lateral-type heterostructures may facilitate efficient electron–hole separation for light detection/harvesting and preserve their type II characteristic up to 12% of uniaxial strain. Basedmore » on the strain-dependent bandgap and band offset, we show that uniaxial tensile strain can significantly increase the power conversion efficiency of these lateral heterostructures. Our results suggest that these strain-engineered lateral heterostructures are promising for optimizing optoelectronic device performance by selectively tuning the energetics of the bandgap.« less