Identification of secondary aerosol precursors emitted by an aircraft turbofan

NASA Astrophysics Data System (ADS)

Kılıç, Doğuşhan; El Haddad, Imad; Brem, Benjamin T.; Bruns, Emily; Bozetti, Carlo; Corbin, Joel; Durdina, Lukas; Huang, Ru-Jin; Jiang, Jianhui; Klein, Felix; Lavi, Avi; Pieber, Simone M.; Rindlisbacher, Theo; Rudich, Yinon; Slowik, Jay G.; Wang, Jing; Baltensperger, Urs; Prévôt, Andre S. H.

2018-05-01

Oxidative processing of aircraft turbine-engine exhausts was studied using a potential aerosol mass (PAM) chamber at different engine loads corresponding to typical flight operations. Measurements were conducted at an engine test cell. Organic gases (OGs) and particle emissions pre- and post-PAM were measured. A suite of instruments, including a proton-transfer-reaction mass spectrometer (PTR-MS) for OGs, a multigas analyzer for CO, CO2, NOx, and an aerosol mass spectrometer (AMS) for nonrefractory particulate matter (NR-PM1) were used. Total aerosol mass was dominated by secondary aerosol formation, which was approximately 2 orders of magnitude higher than the primary aerosol. The chemical composition of both gaseous and particle emissions were also monitored at different engine loads and were thrust-dependent. At idling load (thrust 2.5-7 %), more than 90 % of the secondary particle mass was organic and could mostly be explained by the oxidation of gaseous aromatic species, e.g., benzene; toluene; xylenes; tri-, tetra-, and pentamethyl-benzene; and naphthalene. The oxygenated-aromatics, e.g., phenol, furans, were also included in this aromatic fraction and their oxidation could alone explain up to 25 % of the secondary organic particle mass at idling loads. The organic fraction decreased with thrust level, while the inorganic fraction increased. At an approximated cruise load sulfates comprised 85 % of the total secondary particle mass.

Energy efficient engine high-pressure turbine component rig performance test report

NASA Technical Reports Server (NTRS)

Leach, K. P.

1983-01-01

A rig test of the cooled high-pressure turbine component for the Energy Efficient Engine was successfully completed. The principal objective of this test was to substantiate the turbine design point performance as well as determine off-design performance with the interaction of the secondary flow system. The measured efficiency of the cooled turbine component was 88.5 percent, which surpassed the rig design goal of 86.5 percent. The secondary flow system in the turbine performed according to the design intent. Characterization studies showed that secondary flow system performance is insensitive to flow and pressure variations. Overall, this test has demonstrated that a highly-loaded, transonic, single-stage turbine can achieve a high level of operating efficiency.

Automotive Modules. Vocational Behavioral Objectives: A Guide for Individualizing Instruction.

ERIC Educational Resources Information Center

Westinghouse Learning Corp., New York, NY.

The curriculum guide deals with automotive repair skills at the secondary level of vocational education and industrial arts. It addresses the subject in behavioral terms, as prominent components of the career education concept. Presenting four skill modules, auto body repair, gas engine repair, service, and diesel engine mechanics, the objectives…

Gasoline Engine Mechanics. Performance Objectives. Basic Course.

ERIC Educational Resources Information Center

Jones, Marion

Several intermediate performance objectives and corresponding criterion measures are listed for each of five terminal objectives presented in this curriculum guide for a basic gasoline engine mechanics course at the secondary level. (For the intermediate course guide see CE 010 946.) The materials were developed for a two semester (2 hours daily)…

Augmenting Primary and Secondary Education with Polymer Science and Engineering

ERIC Educational Resources Information Center

Cersonsky, Rose K.; Foster, Leanna L.; Ahn, Taeyong; Hall, Ryan J.; van der Laan, Harry L.; Scott, Timothy F.

2017-01-01

Despite the prevalence of polymers in modern everyday life, there is little introduction to the topic in science education throughout primary or secondary schooling in the United States. Of the few states that do include polymer education, this is only found at the high school level, primarily in biology or chemistry. Over the past year, we have…

Career Motivation of Secondary Students in STEM: A Cross-Cultural Study between Korea and Indonesia

ERIC Educational Resources Information Center

Shin, Sein; Rachmatullah, Arif; Roshayanti, Fenny; Ha, Minsu; Lee, Jun-Ki

2018-01-01

The purpose of this study was to understand the career motivation of secondary students in science, technology, engineering, and mathematics (STEM) by comparing Korean and Indonesian students. Effects of gender and educational level on students' STEM career motivation were also examined. To test for differences, we used Rasch analysis, 3-way…

Secondary Containment Design for the LLNL B801 Diala Oil Tank

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mertesdorf, E.

2016-12-14

Design is to add an extension to the secondary containment of tank T1-A3 at building 801. Piping from the inner tank penetrates the secondary containment tank below the liquid level of the primary tank. To meet Oil Pollution Prevention Regulation 40 CFR 120.7 the single wall piping needs to be provided with secondary containment. Steel Tank Institute (STI) conference publication states: §112.3(d)(1)(iii) –SPCC Plan requirements- Systems shall be designed in accordance with good engineering practice, including consideration of applicable industry standards and that procedures for required inspections and testing have been established. Section 112.7(a)(2) allows for deviations from specific rulemore » requirements, provided the Owner/operator responsible to select, document and implement alternate measure and a PE certifies the SPCC Plan in accordance with good engineering practices, including consideration of industry standards« less

COURSE AND CURRICULUM IMPROVEMENT PROFECTS--MATHEMATICS, SCIENCE, ENGINEERING.

ERIC Educational Resources Information Center

FONTAINE, THOMAS D.

ELEMENTARY, SECONDARY, AND COLLEGE LEVEL SCIENCE COURSE IMPROVEMENT PROJECTS ARE DESCRIBED. INDIVIDUAL PROJECTS ARE CLASSIFIED ACCORDING TO INSTITUTIONAL LEVEL AND ACADEMIC DISCIPLINE. MANY OF THE PROJECTS REPRESENT COMPLETE EDUCATIONAL PROGRAMS AND INCLUDE SUCH MATERIALS AS STUDENT TEXTBOOKS, LABORATORY MANUALS, SUPPLEMENTARY READINGS, TEACHER…

A Study of Trial and Error Learning in Technology, Engineering, and Design Education

ERIC Educational Resources Information Center

Franzen, Marissa Marie Sloan

2016-01-01

The purpose of this research study was to determine if trial and error learning was an effective, practical, and efficient learning method for Technology, Engineering, and Design Education students at the post-secondary level. A mixed methods explanatory research design was used to measure the viability of the learning source. The study sample was…

Basic Principles of Marine Diesel Engines, 8-2. Military Curriculum Materials for Vocational and Technical Education.

ERIC Educational Resources Information Center

Ohio State Univ., Columbus. National Center for Research in Vocational Education.

This volume of student materials for a secondary/postsecondary level course in principles of marine diesel engines is one of a number of military-developed curriculum packages selected for adaptation to vocational instruction and curriculum development in a civilian setting. The purpose of the individualized, self-paced course is to acquaint…

The Effects of Cooperative and Individualistic Learning Structures on Achievement in a College-Level Computer-Aided Drafting Course

ERIC Educational Resources Information Center

Swab, A. Geoffrey

2012-01-01

This study of cooperative learning in post-secondary engineering education investigated achievement of engineering students enrolled in two intact sections of a computer-aided drafting (CAD) course. Quasi-experimental and qualitative methods were employed in comparing student achievement resulting from out-of-class cooperative and individualistic…

Microbial production of isoquinoline alkaloids as plant secondary metabolites based on metabolic engineering research.

PubMed

Sato, Fumihiko; Kumagai, Hidehiko

2013-01-01

Plants produce a variety of secondary metabolites that possess strong physiological activities. Unfortunately, however, their production can suffer from a variety of serious problems, including low levels of productivity and heterogeneous quality, as well as difficulty in raw material supply. In contrast, microorganisms can be used to produce their primary and some of their secondary metabolites in a controlled environment, thus assuring high levels of efficiency and uniform quality. In an attempt to overcome the problems associated with secondary metabolite production in plants, we developed a microbial platform for the production of plant isoquinoline alkaloids involving the unification of the microbial and plant metabolic pathways into a single system. The potential applications of this system have also been discussed.

Microbial production of isoquinoline alkaloids as plant secondary metabolites based on metabolic engineering research

PubMed Central

SATO, Fumihiko; KUMAGAI, Hidehiko

2013-01-01

Plants produce a variety of secondary metabolites that possess strong physiological activities. Unfortunately, however, their production can suffer from a variety of serious problems, including low levels of productivity and heterogeneous quality, as well as difficulty in raw material supply. In contrast, microorganisms can be used to produce their primary and some of their secondary metabolites in a controlled environment, thus assuring high levels of efficiency and uniform quality. In an attempt to overcome the problems associated with secondary metabolite production in plants, we developed a microbial platform for the production of plant isoquinoline alkaloids involving the unification of the microbial and plant metabolic pathways into a single system. The potential applications of this system have also been discussed. PMID:23666088

Motorcycle Mechanic. Teacher Edition.

ERIC Educational Resources Information Center

Baugus, Mickey; Fulkerson, Dan, Ed.

These teacher's materials are for a 19-unit competency-based course on entry-level motorcycle mechanics at the secondary and postsecondary levels. The 19 units are: (1) introduction to motorcycle repair; (2) general safety; (3) tools and equipment; (4) metric measurements; (5) fasteners; (6) service department operations; (7) motorcycle engines;…

What Major Search Engines Like Google, Yahoo and Bing Need to Know about Teachers in the UK?

ERIC Educational Resources Information Center

Seyedarabi, Faezeh

2014-01-01

This article briefly outlines the current major search engines' approach to teachers' web searching. The aim of this article is to make Web searching easier for teachers when searching for relevant online teaching materials, in general, and UK teacher practitioners at primary, secondary and post-compulsory levels, in particular. Therefore, major…

Exploration of NSF-ATE Projects Approaches in the Integration of Technology and Engineering Education at the K-12 Levels

ERIC Educational Resources Information Center

Strobel, Johannes; Mendoza Díaz, Noemi V.

2012-01-01

Access to post-secondary education, specifically in the technical, two-year institution area, is a topic of growing interest in the country. Funding agencies, such as NSF, via the Advanced Technological Education Program (ATE), are supporting initiatives and research aimed at increasing the number of technicians and engineers and improving…

Time-resolved characterization of primary and secondary particle emissions of a modern gasoline passenger car

NASA Astrophysics Data System (ADS)

Karjalainen, P.; Timonen, H.; Saukko, E.; Kuuluvainen, H.; Saarikoski, S.; Aakko-Saksa, P.; Murtonen, T.; Dal Maso, M.; Ahlberg, E.; Svenningsson, B.; Brune, W. H.; Hillamo, R.; Keskinen, J.; Rönkkö, T.

2015-11-01

Changes in traffic systems and vehicle emission reduction technologies significantly affect traffic-related emissions in urban areas. In many densely populated areas the amount of traffic is increasing, keeping the emission level high or even increasing. To understand the health effects of traffic related emissions, both primary and secondary particles that are formed in the atmosphere from gaseous exhaust emissions need to be characterized. In this study we used a comprehensive set of measurements to characterize both primary and secondary particulate emissions of a modern gasoline passenger car. Our aerosol particle study covers the whole process chain in emission formation, from the engine to the atmosphere, and takes into account also differences in driving patterns. We observed that in mass terms, the amount of secondary particles was 13 times higher than the amount of primary particles. The formation, composition, number, and mass of secondary particles was significantly affected by driving patterns and engine conditions. The highest gaseous and particulate emissions were observed at the beginning of the test cycle when the performance of the engine and the catalyst was below optimal. The key parameter for secondary particle formation was the amount of gaseous hydrocarbons in primary emissions; however, also the primary particle population had an influence. Thus, in order to enhance human health and wellbeing in urban areas, our study strongly indicates that in future legislation, special attention should be directed into the reduction of gaseous hydrocarbons.

Potential of secondary aerosol formation from Chinese gasoline engine exhaust.

PubMed

Du, Zhuofei; Hu, Min; Peng, Jianfei; Guo, Song; Zheng, Rong; Zheng, Jing; Shang, Dongjie; Qin, Yanhong; Niu, He; Li, Mengren; Yang, Yudong; Lu, Sihua; Wu, Yusheng; Shao, Min; Shuai, Shijin

2018-04-01

Light-duty gasoline vehicles have drawn public attention in China due to their significant primary emissions of particulate matter and volatile organic compounds (VOCs). However, little information on secondary aerosol formation from exhaust for Chinese vehicles and fuel conditions is available. In this study, chamber experiments were conducted to quantify the potential of secondary aerosol formation from the exhaust of a port fuel injection gasoline engine. The engine and fuel used are common in the Chinese market, and the fuel satisfies the China V gasoline fuel standard. Substantial secondary aerosol formation was observed during a 4-5hr simulation, which was estimated to represent more than 10days of equivalent atmospheric photo-oxidation in Beijing. As a consequence, the extreme case secondary organic aerosol (SOA) production was 426±85mg/kg-fuel, with high levels of precursors and OH exposure. The low hygroscopicity of the aerosols formed inside the chamber suggests that SOA was the dominant chemical composition. Fourteen percent of SOA measured in the chamber experiments could be explained through the oxidation of speciated single-ring aromatics. Unspeciated precursors, such as intermediate-volatility organic compounds and semi-volatile organic compounds, might be significant for SOA formation from gasoline VOCs. We concluded that reductions of emissions of aerosol precursor gases from vehicles are essential to mediate pollution in China. Copyright © 2017. Published by Elsevier B.V.

How to Recruit Women and Girls to the Science, Technology, Engineering, and Math (STEM) Classroom

ERIC Educational Resources Information Center

Milgram, Donna

2011-01-01

Numbers do not exist for the percentage of girls in science, technology, engineering, and math (STEM) academies across the U.S. The most recent career and technical education statistics at the secondary level from the U.S. Department of Education are from 2005, and they show very low numbers of female students in STEM. The absence of women from…

Contingency Power Study for Short Haul Civil Tiltrotor

NASA Technical Reports Server (NTRS)

Eisenberg, Joseph D. (Technical Monitor); Wait, John

2003-01-01

AlliedSignal Engines (AE) defined a number of concepts that significantly increased the horsepower of a turboshaft engine to accommodate the loss of an engine and enable the safe landing of a twin-engined, 40-passenger, short haul civil tiltrotor. From these concepts, "Water/Methanol Injection," a "Better Power Turbine Than Required," and a "Secondary Combustor For Interturbine Reheat" were chosen, based on system safety and economics, for more detailed examination. Engine performance, mission, and cost analysis of these systems indicated contingency power levels of 26 to 70 percent greater than normal rated takeoff could be attained for short durations, thus enabling direct operating cost savings between 2 and 6 percent.

What Is the Function of a Figurine? Can the Repertory Grid Technique Tell?

ERIC Educational Resources Information Center

Persson, Helena Isakssson

2016-01-01

Teaching design and product development at upper secondary school level in Sweden is a matter of interdisciplinary considerations. Education in product development, at this level, prepares students for further studies and career in engineering or industrial design. Knowledge of artefacts is an important element in the education. In coherence with…

Air intake side secondary air supply system for an internal combustion engine with a duty ratio control operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawanabe, T.; Asakura, M.; Shina, T.

1987-09-01

An air intake side secondary air supply system is described for an internal combustion engine having an air intake passage with a carburetor and an exhaust passage, comprising: an air intake side secondary air supply passage communicating with the air intake passage on the downstream side of the carburetor; an open/close valve disposed in the air intake side secondary air supply passage; an oxygen concentration sensor disposed in the exhaust passage; and detection and control means for detecting whether an air-fuel ratio of mixture to be supplied to the engine is leaner or richer with respect to a target air-fuelmore » ratio through a level of an output signal of the oxygen concentration sensor and for periodically actuating the open/close valve, the detection and control means decreasing a valve open period of the open/close valve within each cyclic period by a first predetermined amount when a detected air-fuel ratio of mixture is leaner than the target air-fuel ratio and increasing the valve open period by a second predetermined amount when the detected air-fuel ratio of mixture is richer than the target air-fuel ratio. The second predetermined amount is different from the first predetermined amount.« less

Applied evolutionary theories for engineering of secondary metabolic pathways.

PubMed

Bachmann, Brian O

2016-12-01

An expanded definition of 'secondary metabolism' is emerging. Once the exclusive provenance of naturally occurring organisms, evolved over geological time scales, secondary metabolism increasingly encompasses molecules generated via human engineered biocatalysts and biosynthetic pathways. Many of the tools and strategies for enzyme and pathway engineering can find origins in evolutionary theories. This perspective presents an overview of selected proposed evolutionary strategies in the context of engineering secondary metabolism. In addition to the wealth of biocatalysts provided via secondary metabolic pathways, improving the understanding of biosynthetic pathway evolution will provide rich resources for methods to adapt to applied laboratory evolution. Copyright © 2016 Elsevier Ltd. All rights reserved.

Metabolic engineering with systems biology tools to optimize production of prokaryotic secondary metabolites.

PubMed

Kim, Hyun Uk; Charusanti, Pep; Lee, Sang Yup; Weber, Tilmann

2016-08-27

Covering: 2012 to 2016Metabolic engineering using systems biology tools is increasingly applied to overproduce secondary metabolites for their potential industrial production. In this Highlight, recent relevant metabolic engineering studies are analyzed with emphasis on host selection and engineering approaches for the optimal production of various prokaryotic secondary metabolites: native versus heterologous hosts (e.g., Escherichia coli) and rational versus random approaches. This comparative analysis is followed by discussions on systems biology tools deployed in optimizing the production of secondary metabolites. The potential contributions of additional systems biology tools are also discussed in the context of current challenges encountered during optimization of secondary metabolite production.

Knowledge Integration and Wise Engineering

ERIC Educational Resources Information Center

Chiu, Jennifer L.; Linn, M. C.

2011-01-01

Recent efforts in engineering education focus on introducing engineering into secondary math and science courses to improve science, technology, engineering, and math (STEM) education (NAS, 2010). Infusing engineering into secondary classrooms can increase awareness of and interest in STEM careers, help students see the relevance of science and…

JT8D-15/17 High Pressure Turbine Root Discharged Blade Performance Improvement. [engine design

NASA Technical Reports Server (NTRS)

Janus, A. S.

1981-01-01

The JT8D high pressure turbine blade and seal were modified, using a more efficient blade cooling system, improved airfoil aerodynamics, more effective control of secondary flows, and improved blade tip sealing. Engine testing was conducted to determine the effect of these improvements on performance. The modified turbine package demonstrated significant thrust specific fuel consumption and exhaust gas temperature improvements in sea level and altitude engine tests. Inspection of the improved blade and seal hardware after testing revealed no unusual wear or degradation.

Effects of single-gender mathematics classrooms on self-perception of mathematical ability and post secondary engineering paths: an Australian case study

NASA Astrophysics Data System (ADS)

Tully, D.; Jacobs, B.

2010-08-01

This study focused on a population of female engineering students, probing the influences of their secondary school experience on their choice to pursue an engineering course of study at university. The motivating question is: Do unique opportunities exist in an all-female secondary school mathematics classroom, which impact a young woman's self-perception of her mathematics ability as well as promote a positive path towards an engineering-based university major? Using both qualitative and quantitative data collection instruments, this study examined a sample of Australian engineering students enrolled at the University of Technology, Sydney (UTS). Demographic statistics show that 40% of UTS' female engineering student population attended a single-gender secondary school, indicating a potential influence of school type (single-gender) on engineering enrolment patterns. Female students were primarily motivated to pursue a post secondary engineering path because of a self-belief that they are good at mathematics. In contrast, male students were more influenced by positive male role models of family members who are practising engineers. In measures of self- perception of mathematical skill and ability, female students from single-gender schools outscored their male engineering counterparts. Additionally, female students seem to benefit from verbal encouragement, contextualisation, same gender problem-solving groups and same gender classroom dynamics.

Reverse Flow Engine Core Having a Ducted Fan with Integrated Secondary Flow Blades

NASA Technical Reports Server (NTRS)

Kisska, Michael K. (Inventor); Princen, Norman H. (Inventor); Kuehn, Mark S. (Inventor); Cosentino, Gary B. (Inventor)

2014-01-01

Secondary air flow is provided for a ducted fan having a reverse flow turbine engine core driving a fan blisk. The fan blisk incorporates a set of thrust fan blades extending from an outer hub and a set of integral secondary flow blades extending intermediate an inner hub and the outer hub. A nacelle provides an outer flow duct for the thrust fan blades and a secondary flow duct carries flow from the integral secondary flow blades as cooling air for components of the reverse flow turbine engine.

78 FR 54638 - Request for Information To Inform the Title III Technical Assistance Agenda and the Future...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-05

... assistance needed and at what level (e.g., SEA, LEA, school or classroom)? a. Common Core State Standards or..., or students; k. ESEA flexibility and ELs; l. Science, technology, engineering, and math (STEM...; o. ELs at the secondary school level; p. ELs served under IDEA; q. Civil rights and ELs; or r. Other...

The Science-Technology-Engineering-Mathematics (STEM) Initiative at Stephen F Austin State University

ERIC Educational Resources Information Center

Gruebel, Robert W.; Childs, Kimberly

2013-01-01

The Texas statewide assessment of academic skills in 1997 indicated that >55 % of the student population failed to master the mathematics objectives set by the test criteria and 42 % of the mathematics teachers at the secondary level in the East Texas region were categorized as underqualified to teach mathematics at that level. The issue of…

Engineering. Program CIP: 14.1901

ERIC Educational Resources Information Center

Agee, Kelly, Ed.

2009-01-01

Secondary vocational-technical education programs in Mississippi are faced with many challenges resulting from sweeping educational reforms at the national and state levels. Schools and teachers are increasingly being held accountable for providing true learning activities to every student in the classroom. This accountability is measured through…

Prediction of X-33 Engine Dynamic Environments

NASA Technical Reports Server (NTRS)

Shi, John J.

1999-01-01

Rocket engines normally have two primary sources of dynamic excitation. The first source is the injector and the combustion chambers that generate wide band random vibration. The second source is the turbopumps, which produce lower levels of wide band random vibration as well as sinusoidal vibration at frequencies related to the rotating speed and multiples thereof. Additionally, the pressure fluctuations due to flow turbulence and acoustics represent secondary sources of excitation. During the development stage, in order to design/size the rocket engine components, the local dynamic environments as well as dynamic interface loads have to be defined.

Seals/Secondary Fluid Flows Workshop 1997; Volume I

NASA Technical Reports Server (NTRS)

Hendricks, Robert C. (Editor)

2006-01-01

The 1997 Conference provided discussions and data on (a) program overviews, (b) developments in seals and secondary air management systems, (c) interactive seals flows with secondary air or fluid flows and powerstream flows, (d) views of engine externals and limitations, (e) high speed engine research sealing needs and demands, and (f) a short course on engine design development margins. Sealing concepts discussed include, mechanical rim and cavity seals, leaf, finger, air/oil, rope, floating-brush, floating-T-buffer, and brush seals. Engine externals include all components of engine fluid systems, sensors and their support structures that lie within or project through the nacelle. The clean features of the nacelle belie the minefield of challenges and opportunities that lie within. Seals; Secondary air flows; Rotordynamics; Gas turbine; Aircraft; CFD; Testing; Turbomachinery

Effects of Single-Gender Mathematics Classrooms on Self-Perception of Mathematical Ability and Post Secondary Engineering Paths: An Australian Case Study

ERIC Educational Resources Information Center

Tully, D.; Jacobs, B.

2010-01-01

This study focused on a population of female engineering students, probing the influences of their secondary school experience on their choice to pursue an engineering course of study at university. The motivating question is: Do unique opportunities exist in an all-female secondary school mathematics classroom, which impact a young woman's…

Examination of engineering design teacher self-efficacy and knowledge base in secondary technology education and engineering-related courses

NASA Astrophysics Data System (ADS)

Vessel, Kanika Nicole

2011-12-01

There is an increasing demand for individuals with engineering education and skills of varying fields in everyday life. With the proper education students of high-needs schools can help meet the demand for a highly skilled and educated workforce. Researchers have assumed the supply and demand has not been met within the engineering workforce as a result of students' collegiate educational experiences, which are impacted by experiences in K-12 education. Although factors outside of the classroom contribute to the inability of universities to meet the increasing demand for the engineering workforce, most noted by researchers is the academic unpreparedness of freshman engineering students. The unpreparedness of entering freshman engineering students is a result of K-12 classroom experiences. This draws attention not only to the quality and competence of teachers present in the K-12 classroom, but the type of engineering instruction these students are receiving. This paper was an effort to systematically address one of the more direct and immediate factors impacting freshman engineering candidates, the quality of secondary engineering educators. Engineers develop new ideas using the engineering design process, which is taught at the collegiate level, and has been argued to be the best approach to teach technological literacy to all K-12 students. However, it is of importance to investigate whether technology educators have the knowledge and understanding of engineering design, how to transfer that knowledge in the classroom to students through instructional strategies, and their perception of their ability to do that. Therefore, the purpose of this study is to show the need for examining the degree to which technology and non-technology educators are implementing elements of engineering design in the curriculum.

A design strategy for the use of vortex generators to manage inlet-engine distortion using computational fluid dynamics

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.; Levy, Ralph

1991-01-01

A reduced Navier-Stokes solution technique was successfully used to design vortex generator installations for the purpose of minimizing engine face distortion by restructuring the development of secondary flow that is induced in typical 3-D curved inlet ducts. The results indicate that there exists an optimum axial location for this installation of corotating vortex generators, and within this configuration, there exists a maximum spacing between generator blades above which the engine face distortion increases rapidly. Installed vortex generator performance, as measured by engine face circumferential distortion descriptors, is sensitive to Reynolds number and thereby the generator scale, i.e., the ratio of generator blade height to local boundary layer thickness. Installations of corotating vortex generators work well in terms of minimizing engine face distortion within a limited range of generator scales. Hence, the design of vortex generator installations is a point design, and all other conditions are off design. In general, the loss levels associated with a properly designed vortex generator installation are very small; thus, they represent a very good method to manage engine face distortion. This study also showed that the vortex strength, generator scale, and secondary flow field structure have a complicated and interrelated influence over engine face distortion, over and above the influence of the initial arrangement of generators.

Improving K-12 STEM Education Outcomes through Technological Integration

ERIC Educational Resources Information Center

Urban, Michael J., Ed.; Falvo, David A., Ed.

2016-01-01

The application of technology in classroom settings has equipped educators with innovative tools and techniques for effective teaching practice. Integrating digital technologies at the elementary and secondary levels helps to enrich the students' learning experience and maximize competency in the areas of science, technology, engineering, and…

Research in Electronic/Electrical Engineering at British Universities,

DTIC Science & Technology

1981-04-30

and Wales. There are basically two sets of examinations, the Ordinary and Advanced, known as Ŕ and A levels ." O levels are normally taken after 4 or 5...years of secondary school; A levels after 6 or 7 years. Admission to a professional school, such as one that trains nurses, for example, or...determined by the particular university, but 4 subjects is a common number. In addition, a "pass" in several A levels is required. Suppose a young man wishes

Ohio Engineering Technologies Competency Profile.

ERIC Educational Resources Information Center

Miller, Lavonna; Draeger, Meg; Bowermeister, Bob; Wancho, Richard

This document, which lists engineering technologies competencies as identified by representatives from business and industry as well as secondary and post-secondary educators throughout Ohio, is intended to assist individuals and organizations in developing college tech prep programs that will prepare students from secondary through post-secondary…

Biotechnology Apprenticeship for Secondary-Level Students: Teaching Advanced Cell Culture Techniques for Research.

ERIC Educational Resources Information Center

Lewis, Jennifer R.; Kotur, Mark S.; Butt, Omar; Kulcarni, Sumant; Riley, Alyssa A.; Ferrell, Nick; Sullivan, Kathryn D.; Ferrari, Mauro

2002-01-01

Discusses small-group apprenticeships (SGAs) as a method for introducing cell culture techniques to high school participants. Teaches cell culture practices and introduces advance imaging techniques to solve various biomedical engineering problems. Clarifies and illuminates the value of small-group laboratory apprenticeships. (Author/KHR)

A Pilot Meta-Analysis of Computer-Based Scaffolding in STEM Education

ERIC Educational Resources Information Center

Belland, Brian R.; Walker, Andrew E.; Olsen, Megan Whitney; Leary, Heather

2015-01-01

This paper employs meta-analysis to determine the influence of computer-based scaffolding characteristics and study and test score quality on cognitive outcomes in science, technology, engineering, and mathematics education at the secondary, college, graduate, and adult levels. Results indicate that (a) computer-based scaffolding positively…

TIMMS Advanced 2015 Assessment Frameworks

ERIC Educational Resources Information Center

Mullis, Ina V. S., Ed.; Martin, Michael O., Ed.

2014-01-01

It is critical for countries to ensure that capable secondary school students receive further preparation in advanced mathematics and science, so that they are ready to enter challenging university-level studies that prepare them for careers in science, technology, engineering, and mathematics (STEM) fields. This group of students will become the…

Integrating the protein and metabolic engineering toolkits for next-generation chemical biosynthesis.

PubMed

Pirie, Christopher M; De Mey, Marjan; Jones Prather, Kristala L; Ajikumar, Parayil Kumaran

2013-04-19

Through microbial engineering, biosynthesis has the potential to produce thousands of chemicals used in everyday life. Metabolic engineering and synthetic biology are fields driven by the manipulation of genes, genetic regulatory systems, and enzymatic pathways for developing highly productive microbial strains. Fundamentally, it is the biochemical characteristics of the enzymes themselves that dictate flux through a biosynthetic pathway toward the product of interest. As metabolic engineers target sophisticated secondary metabolites, there has been little recognition of the reduced catalytic activity and increased substrate/product promiscuity of the corresponding enzymes compared to those of central metabolism. Thus, fine-tuning these enzymatic characteristics through protein engineering is paramount for developing high-productivity microbial strains for secondary metabolites. Here, we describe the importance of protein engineering for advancing metabolic engineering of secondary metabolism pathways. This pathway integrated enzyme optimization can enhance the collective toolkit of microbial engineering to shape the future of chemical manufacturing.

The Nexus between Science Literacy & Technical Literacy: A State by State Analysis of Engineering Content in State Science Standards

ERIC Educational Resources Information Center

Koehler, Catherine M.; Faraclas, Elias; Giblin, David; Moss, David M.; Kazerounian, Kazem

2013-01-01

This study explores how engineering concepts are represented in secondary science standards across the nation by examining how engineering and technical concepts are infused into these frameworks. Secondary science standards from 49 states plus the District of Columbia were analyzed and ranked based on how many engineering concepts were found.…

An advanced concept secondary power systems study for an advanced transport technology aircraft

NASA Technical Reports Server (NTRS)

1972-01-01

The application of advanced technology to the design of an integrated secondary power system for future near-sonic long-range transports was investigated. The study showed that the highest payoff is achieved by utilizing secondary power equipment that contributes to minimum cruise drag. This is best accomplished by the use of the dedicated auxiliary power unit concept (inflight APU) as the prime power source for an airplane with a body-mounted engine or by the use of the internal engine generator concept (electrical power extraction from the propulsion engine) for an airplane with a wing-pod-mounted engine.

Secondary electric power generation with minimum engine bleed

NASA Technical Reports Server (NTRS)

Tagge, G. E.

1983-01-01

Secondary electric power generation with minimum engine bleed is discussed. Present and future jet engine systems are compared. The role of auxiliary power units is evaluated. Details of secondary electric power generation systems with and without auxiliary power units are given. Advanced bleed systems are compared with minimum bleed systems. A cost model of ownership is given. The difference in the cost of ownership between a minimum bleed system and an advanced bleed system is given.

Variable compression ratio device for internal combustion engine

DOEpatents

Maloney, Ronald P.; Faletti, James J.

2004-03-23

An internal combustion engine, particularly suitable for use in a work machine, is provided with a combustion cylinder, a cylinder head at an end of the combustion cylinder and a primary piston reciprocally disposed within the combustion cylinder. The cylinder head includes a secondary cylinder and a secondary piston reciprocally disposed within the secondary cylinder. An actuator is coupled with the secondary piston for controlling the position of the secondary piston dependent upon the position of the primary piston. A communication port establishes fluid flow communication between the combustion cylinder and the secondary cylinder.

A Qatari perspective on women in the engineering pipeline: an exploratory study

NASA Astrophysics Data System (ADS)

Fauziah Sulaiman, Noor; AlMuftah, Hend

2010-10-01

Under-representation of women in engineering has received a great deal of attention, but remained limited largely to a Western context. Thus, this article aims to unveil the barriers to progress, tracking the performance and the emerging trend of success at the undergraduate level of women in engineering in a different cultural dimension. Secondary research, particularly statistical data of female undergraduate engineering students at Qatar University (QU), is used in this study. Findings show that the booming economic development and access to modern education are the key drivers that change the position of women in Qatari society. A shift away from a masculine-dominated society to a more balance masculine/feminine society was identified as the impetus for better enrolment and achievement of female engineering students in Qatar. Similar to the trend in the USA, recruitment and not retention was the reason behind the under-representation of female undergraduate engineering students at QU.

Influence of Person Epistemology on Research Design: Implications for Research Education

ERIC Educational Resources Information Center

Singh, Viren

2017-01-01

This study was aimed at determining whether a specific research methodology was dominant within a cohort of master's level engineering management students and, if so, whether this preference was directed by their personal epistemology, rather than the dictates of their research questions. Secondary data were used to determine the dominant research…

Characteristics of Exemplary Science, Technology, Engineering, and Math (STEM)-Related Experiential Learning Opportunities

ERIC Educational Resources Information Center

Simmons, Jamie Munn

2017-01-01

Experiential opportunities at the secondary level give students the "intimate and necessary relation between the processes of actual experience and education" (Dewey, 1938, p. 19-20). Career and Technical Education classes (CTE) and co-curricular experiences, one type of experiential learning, underpin and cultivate student curiosity and…

Using Mathematics and Engineering to Solve Problems in Secondary Level Biology

ERIC Educational Resources Information Center

Cox, Charles; Reynolds, Birdy; Schunn, Christian; Schuchardt, Anita

2016-01-01

There are strong classroom ties between mathematics and the sciences of physics and chemistry, but those ties seem weaker between mathematics and biology. Practicing biologists realize both that there are interesting mathematics problems in biology, and that viewing classroom biology in the context of another discipline could support students'…

Helping Students Succeed within Secondary-Level STEM Content: Using the "T" in STEM to Improve Literacy Skills

ERIC Educational Resources Information Center

Kennedy, Michael J.; Wexler, Jade

2013-01-01

Literacy and other content-specific demands presented within science, technology, engineering, and mathematics (STEM) coursework can overwhelm all students and especially students with learning challenges. Although STEM content is often complex in itself (e.g., numerous multisyllabic words, lengthy expository texts, abstract concepts), some…

Biotechnology Apprenticeship for Secondary-Level Students: Teaching Advanced Cell Culture Techniques for Research

ERIC Educational Resources Information Center

Lewis, Jennifer R.; Kotur, Mark S.; Butt, Omar; Kulcarni, Sumant; Riley, Alyssa A.; Ferrell, Nick; Sullivan, Kathryn D.; Ferrari, Mauro

2002-01-01

The purpose of this article is to discuss "small-group apprenticeships (SGAs)" as a method to instruct cell culture techniques to high school participants. The study aimed to teach cell culture practices and to introduce advanced imaging techniques to solve various biomedical engineering problems. Participants designed and completed experiments…

Integrated engine-generator concept for aircraft electric secondary power

NASA Technical Reports Server (NTRS)

Secunde, R. R.; Macosko, R. P.; Repas, D. S.

1972-01-01

The integrated engine-generator concept of locating an electric generator inside an aircraft turbojet or turbofan engine concentric with, and driven by, one of the main engine shafts is discussed. When properly rated, the generator can serve as an engine starter as well as a generator of electric power. The electric power conversion equipment and generator controls are conveniently located in the aircraft. Preliminary layouts of generators in a large engine together with their physical sizes and weights indicate that this concept is a technically feasible approach to aircraft secondary power.

Integrated engine generator for aircraft secondary power

NASA Technical Reports Server (NTRS)

Secunde, R. R.

1972-01-01

An integrated engine-generator for aircraft secondary power generation is described. The concept consists of an electric generator located inside a turbojet or turbofan engine and both concentric with and driven by one of the main engine shafts. The electric power conversion equipment and generator controls are located in the aircraft. When properly rated, the generator serves as an engine starter as well as a source of electric power. This configuration reduces or eliminates the need for an external gear box on the engine and permits reduction in the nacelle diameter.

Engineered Surfaces to Control Secondary Electron Yield for Multipactor Suppression

DTIC Science & Technology

2017-09-14

Radio Engineers ( IRE ) Transactions on Electron Devices. The first paper , published by Preist and Talcott, examined damage to RF windows in klystrons...Secondary electron emission data for aluminum referenced by Hatch in his 1961 paper showing a typical SEY (δ) curve (top) and typical energy...83 IRE : Institute of Radio Engineers

Engine Tune-Up Service. Unit 4: Secondary Circuit. Posttests. Automotive Mechanics Curriculum.

ERIC Educational Resources Information Center

Morse, David T.

This book of posttests is designed to accompany the Engine Tune-Up Service Student Guide for Unit 4, Secondary Circuit, available separately as CE 031 214. Focus of the posttests is testing and servicing the secondary ignition circuit. One multiple choice posttest is provided that covers the seven performance objectives contained in the unit. (No…

A Glance at Performance Management in Departments for Preparation of Secondary Mathematics, Engineering, Technology and Science Teachers in France

ERIC Educational Resources Information Center

Tchibozo, Guy

2005-01-01

In France, secondary teachers are public sector employees. Becoming a STEM (Science, Technology, Engineering, and Math) teacher in secondary education is subject to passing public competitive entry examinations. Preparation for these examinations is provided in College Departments, which are essentially assessed on the basis of their success…

Ultra-High Bypass Ratio Jet Noise

NASA Technical Reports Server (NTRS)

Low, John K. C.

1994-01-01

The jet noise from a 1/15 scale model of a Pratt and Whitney Advanced Ducted Propulsor (ADP) was measured in the United Technology Research Center anechoic research tunnel (ART) under a range of operating conditions. Conditions were chosen to match engine operating conditions. Data were obtained at static conditions and at wind tunnel Mach numbers of 0.2, 0.27, and 0.35 to simulate inflight effects on jet noise. Due to a temperature dependence of the secondary nozzle area, the model nozzle secondary to primary area ratio varied from 7.12 at 100 percent thrust to 7.39 at 30 percent thrust. The bypass ratio varied from 10.2 to 11.8 respectively. Comparison of the data with predictions using the current Society of Automotive Engineers (SAE) Jet Noise Prediction Method showed that the current prediction method overpredicted the ADP jet noise by 6 decibels. The data suggest that a simple method of subtracting 6 decibels from the SAE Coaxial Jet Noise Prediction for the merged and secondary flow source components would result in good agreement between predicted and measured levels. The simulated jet noise flight effects with wind tunnel Mach numbers up to 0.35 produced jet noise inflight noise reductions up to 12 decibels. The reductions in jet noise levels were across the entire jet noise spectra, suggesting that the inflight effects affected all source noise components.

Cost of curative pediatric services in a public sector setting.

PubMed

Krishnan, Anand; Arora, Narendra K; Pandav, Chandrakant S; Kapoor, Suresh K

2005-08-01

To estimate the cost of ambulatory (out-patient) and in-patient pediatric health services for the year 1999 provided by All India Institute of Medical Sciences (AIIMS) at all the three levels-primary, secondary and tertiary level. The costing module developed by Children's Vaccines Initiative (CVI) was used. This rapid assessment tool focuses on collection of data at macro level by using key informants like doctors, nursing staff, accountant, store keeper, engineer etc. Cost per beneficiary was estimated separately for in-patients and out-patients and was calculated by dividing the total cost of the services by the number of beneficiaries for the year 1999. For the out-patient, the beneficiaries were the total out-patient attendees and for the in-patient, it was the total pediatric admissions multiplied by mean duration of stay in days. The cost per out-patient visit was INR.20.2 (US0.44 dollars@1US dollars=INR.46) at primary level, higher than INR14.5 (US0.31 dollars) at the secondary level, while at tertiary level it was INR 33.8 (US 0.73 dollars). At the primary and secondary level, non-physician cost was more than the physician cost, and for tertiary level, physician cost was much higher than the other costs. There were no in-patient services at primary level. The cost of in-patient services at secondary level was estimated as INR 419.30 (US 9.1 dollars) per patient per day with a bed occupancy rate of 60%. Two-fifths of the cost was due to nursing and other supportive staff and one fifth due to the doctor costs and overhead costs. The unit cost of INR 928 (US 20.2 dollars) per patient per day incurred at AIIMS with a bed occupancy rate of 100% was almost twice that of secondary level. In contrast to the secondary level, almost half the total costs at tertiary level was due to the doctors costs. Effective use of resources at lower level of care especially ambulatory care at primary level and inpatient care at secondary level can result in much higher savings for the system and also, the society. These would need to be appropriately strengthened.

SECONDARY GENERAL MOTORS DIESEL ENGINE WITH CONNECTION TO REDUCTION GEAR ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

SECONDARY GENERAL MOTORS DIESEL ENGINE WITH CONNECTION TO REDUCTION GEAR BELT DRIVE SYSTEM, LOOKING SOUTH. - Mad River Glen, Single Chair Ski Lift, 62 Mad River Glen Resort Road, Fayston, Washington County, VT

Engineering for Sustainable Energy Education within Suburban, Urban and Developing Secondary Schools

ERIC Educational Resources Information Center

Kaikai, Moijue; Baker, Erin

2016-01-01

It is crucial that the younger generation be included in the conversation of sustainable development, given the urgent need of a global transition to cleaner energy solutions. Sustainable energy engineering (SEE) taught as early as secondary school can not only increase the number of students that will potentially study engineering to solve global…

DISC BRAKE SYSTEM (CENTER), INCLUDING BELT DRIVE TO SECONDARY GENERAL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DISC BRAKE SYSTEM (CENTER), INCLUDING BELT DRIVE TO SECONDARY GENERAL MOTORS ENGINE (LEFT)AND FERREL REDUCTION GEAR CONNECTION TO ALLIS-CHALMERS DIESEL ENGINE (RIGHT), LOOKING NORTH. NOTE TORQUE CONVERTER (TOP) AND THROTTLE (BELOW) LINES CONNECTING TO PRIMARY ENGINE. - Mad River Glen, Single Chair Ski Lift, 62 Mad River Glen Resort Road, Fayston, Washington County, VT

Control installation for the proportioning of a secondary air quantity for improvement of the combustion in internal combustion engines or the afterburning of the exhaust gases of internal combustion engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bockelmann, W.; Groezinger, H.; Woebky, P.U.

1977-01-04

A control installation is described for the dosing or proportioning of a secondary air quantity for the improvement of combustion in internal combustion engines, or the after-burning of the exhaust gases of internal combustion engines. An auxiliary arrangement is responsive to an emergency signal for effecting the prompt shutting-off of the secondary air. The emergency signal may be initiated in response to a failure in the ignition voltage of the internal combustion engine; an increase in the hydrocarbon content of the exhaust gases; a disparity between the position of the mixture dosing element and the engine rotational speed; the exceedingmore » of a limiting temperature in the exhaust gas manifold; or the exceeding of a limiting temperature in the afterburner.« less

Engine Tune-up Service. Unit 4: Secondary Circuit. Review Exercise Book. Automotive Mechanics Curriculum.

ERIC Educational Resources Information Center

Bacon, E. Miles

This book of pretests and review exercises is designed to accompany the Engine Tune-Up Service Student Guide for Unit 4, Secondary Circuit, available separately as CE 031 214. Focus of the exercises and pretests is testing and servicing the secondary ignition circuit. Pretests and performance checklists are provided for each of the seven…

Engine Tune-Up Service. Unit 4: Secondary Circuit. Student Guide. Automotive Mechanics Curriculum.

ERIC Educational Resources Information Center

Bacon, E. Miles

This student guide is for Unit 4, Secondary Circuit, in the Engine Tune-Up Service portion of the Automotive Mechanics Curriculum. It deals with how to test and service the secondary ignition circuit. A companion review exercise book and posttests are available separately as CE 031 215-216. An introduction tells how this unit fits into the total…

Military Curricula for Vocational & Technical Education. General Purpose Vehicle Mechanic, Blocks IV-V, 8-11.

ERIC Educational Resources Information Center

Ohio State Univ., Columbus. National Center for Research in Vocational Education.

This plan of instruction, lesson plans, and student materials (programed texts, workbooks, and study guides) for a secondary-postsecondary level course in engine mechanics is one of a number of military-developed curriculum packages selected for adaptation to vocational instruction and curriculum development in a civilian setting. It is the third…

Military Curricula for Vocational & Technical Education. General Purpose Vehicle Mechanic, Block III, 8-10.

ERIC Educational Resources Information Center

Ohio State Univ., Columbus. National Center for Research in Vocational Education.

This plan of instruction, lesson plans, and student materials (study guides, workbooks, and programed texts) for a secondary-postsecondary level course in engine mechanics is one of a number of military-developed curriculum packages selected for adaptation to vocational instruction and curriculum development in a civilian setting. It is the second…

Encouraging More Women into Computer Science: Initiating a Single-Sex Intervention Program in Sweden.

ERIC Educational Resources Information Center

Brandell, Gerd; Carlsson, Svante; Eklbom, Hakan; Nord, Ann-Charlotte

1997-01-01

Describes the process of starting a new program in computer science and engineering that is heavily based on applied mathematics and only open to women. Emphasizes that success requires considerable interest in mathematics and curiosity about computer science among female students at the secondary level and the acceptance of the single-sex program…

NASA's educational programs

NASA Technical Reports Server (NTRS)

Brown, Robert W.

1990-01-01

The educational programs of NASA's Educational Affairs Division are examined. The problem of declining numbers of science and engineering students is reviewed. The various NASA educational programs are described, including programs at the elementary and secondary school levels, teacher education programs, and undergraduate, graduate, and university faculty programs. The coordination of aerospace education activities and future plans for increasing NASA educational programs are considered.

Thinking Design and Pedagogy: An Examination of Five Canadian Post-Secondary Courses in Design Thinking

ERIC Educational Resources Information Center

Donar, Ann

2011-01-01

At the tertiary level today, courses on design thinking can be found in diverse programs in and beyond the realm of traditional design disciplines. Across Canada, design thinking courses feature in communication, culture and information technology, and business and engineering. This paper reports findings from a study that investigated the…

Middle School Science Curriculum Design and 8th Grade Student Achievement in Massachusetts Public Schools

ERIC Educational Resources Information Center

Clifford, Betsey A.

2016-01-01

The Massachusetts Department of Elementary and Secondary Education (DESE) released proposed Science and Technology/Engineering standards in 2013 outlining the concepts that should be taught at each grade level. Previously, standards were in grade spans and each district determined the method of implementation. There are two different methods used…

Computing and STEM in Greece: Gender Representation of Students and Teachers during the Decade 2002/2012

ERIC Educational Resources Information Center

Kordaki, Maria; Berdousis, Ioannis

2017-01-01

Female student representation in Computing and Science, Technology, Engineering and Mathematics (STEM) Tertiary education is under-researched in a number of countries including Greece, while studies on female secondary level education teacher representation in Computing and STEM have not yet been reported. This study focuses on the investigation…

The Future of Metabolic Engineering and Synthetic Biology: Towards a Systematic Practice

PubMed Central

Yadav, Vikramaditya G.; De Mey, Marjan; Lim, Chin Giaw; Ajikumar, Parayil Kumaran; Stephanopoulos, Gregory

2012-01-01

Industrial biotechnology promises to revolutionize conventional chemical manufacturing in the years ahead, largely owing to the excellent progress in our ability to re-engineer cellular metabolism. However, most successes of metabolic engineering have been confined to over-producing natively synthesized metabolites in E. coli and S. cerevisiae. A major reason for this development has been the descent of metabolic engineering, particularly secondary metabolic engineering, to a collection of demonstrations rather than a systematic practice with generalizable tools. Synthetic biology, a more recent development, faces similar criticisms. Herein, we attempt to lay down a framework around which bioreaction engineering can systematize itself just like chemical reaction engineering. Central to this undertaking is a new approach to engineering secondary metabolism known as ‘multivariate modular metabolic engineering’ (MMME), whose novelty lies in its assessment and elimination of regulatory and pathway bottlenecks by re-defining the metabolic network as a collection of distinct modules. After introducing the core principles of MMME, we shall then present a number of recent developments in secondary metabolic engineering that could potentially serve as its facilitators. It is hoped that the ever-declining costs of de novo gene synthesis; the improved use of bioinformatic tools to mine, sort and analyze biological data; and the increasing sensitivity and sophistication of investigational tools will make the maturation of microbial metabolic engineering an autocatalytic process. Encouraged by these advances, research groups across the world would take up the challenge of secondary metabolite production in simple hosts with renewed vigor, thereby adding to the range of products synthesized using metabolic engineering. PMID:22629571

Army Research Concerns in Engine Sealing

NASA Technical Reports Server (NTRS)

Bill, Robert C.

1991-01-01

The Army Propulsion Directorate is primarily concerned with small engine technology, where sealing performance is most critical. Tip leakage and secondary flow losses have a much greater performance impact on small engine aero-components than on large engines. A brief survey and critique of presently employed sealing concepts is presented. Some recent new research thrusts that show promise for substantial improvement are discussed. An especially promising approach for small engine applications is brush seals. Brush seal concepts are being considered for outer air seal and secondary airflow system seal locations.

Identifying Perceptions That Contribute to the Development of Successful Project Lead the Way Pre-Engineering Programs in Utah

ERIC Educational Resources Information Center

McMullin, Keith; Reeve, Edward

2014-01-01

An educational crisis has been reported from many scholarly platforms for the last quarter century. The United States is faced with the challenge of providing a secondary science, technology, engineering, and math (STEM) education, especially in secondary pre-engineering, that will lead its students to the fulfillment of academic and domestic…

Secondary Organic Aerosol Production from Gasoline Vehicle Exhaust: Effects of Engine Technology, Cold Start, and Emission Certification Standard.

PubMed

Zhao, Yunliang; Lambe, Andrew T; Saleh, Rawad; Saliba, Georges; Robinson, Allen L

2018-02-06

Secondary organic aerosol (SOA) formation from dilute exhaust from 16 gasoline vehicles was investigated using a potential aerosol mass (PAM) oxidation flow reactor during chassis dynamometer testing using the cold-start unified cycle (UC). Ten vehicles were equipped with gasoline direct injection engines (GDI vehicles) and six with port fuel injection engines (PFI vehicles) certified to a wide range of emissions standards. We measured similar SOA production from GDI and PFI vehicles certified to the same emissions standard; less SOA production from vehicles certified to stricter emissions standards; and, after accounting for differences in gas-particle partitioning, similar effective SOA yields across different engine technologies and certification standards. Therefore the ongoing, dramatic shift from PFI to GDI vehicles in the United States should not alter the contribution of gasoline vehicles to ambient SOA and the natural replacement of older vehicles with newer ones certified to stricter emissions standards should reduce atmospheric SOA levels. Compared to hot operations, cold-start exhaust had lower effective SOA yields, but still contributed more SOA overall because of substantially higher organic gas emissions. We demonstrate that the PAM reactor can be used as a screening tool for vehicle SOA production by carefully accounting for the effects of the large variations in emission rates.

Noise characteristics of grass-trimming machine engines and their effect on operators.

PubMed

Mallick, Zulquernain; Badruddin, Irfan Anjum; Khaleed Hussain, M T; Salman Ahmed, N J; Kanesan, Jeevan

2009-01-01

Over the last few years, interaction of humans with noisy power-driven agricultural tools and its possible adverse after effects have been realized. Grass-trimmer engine is the primary source of noise and the use of motorized cutter, spinning at high speed, is the secondary source of noise to which operators are exposed. In the present study, investigation was carried out to determine the effect of two types of grass-trimming machine engines (SUM 328 SE and BG 328) noise on the operators in real working environment. It was found that BG-328 and SUM-328 SE produced high levels of noise, of the order of 100 and 105 dB(A), respectively, to which operators are exposed while working. It was also observed that situation aggravates when a number of operators simultaneously operate resulting in still higher levels of noise. Operators should be separated 15 meters from each other in order to avoid the combined level of noise exposure while working with these machines. It was found that SPL, of the grass-trimmer machine engines (BG-328 and SUM-328 SE), were higher than the limit of noise recommended by ISO, NIOSH, and OSHA for an 8-hour workday. Such a high level of noise exposure may cause physiological and psychological problems to the operators in long run.

Comparison of primary and secondary particle formation from natural gas engine exhaust and of their volatility characteristics

NASA Astrophysics Data System (ADS)

Alanen, Jenni; Simonen, Pauli; Saarikoski, Sanna; Timonen, Hilkka; Kangasniemi, Oskari; Saukko, Erkka; Hillamo, Risto; Lehtoranta, Kati; Murtonen, Timo; Vesala, Hannu; Keskinen, Jorma; Rönkkö, Topi

2017-07-01

Natural gas usage in the traffic and energy production sectors is a growing trend worldwide; thus, an assessment of its effects on air quality, human health and climate is required. Engine exhaust is a source of primary particulate emissions and secondary aerosol precursors, which both contribute to air quality and can cause adverse health effects. Technologies, such as cleaner engines or fuels, that produce less primary and secondary aerosols could potentially significantly decrease atmospheric particle concentrations and their adverse effects. In this study, we used a potential aerosol mass (PAM) chamber to investigate the secondary aerosol formation potential of natural gas engine exhaust. The PAM chamber was used with a constant UV-light voltage, which resulted in relatively long equivalent atmospheric ages of 11 days at most. The studied retro-fitted natural gas engine exhaust was observed to form secondary aerosol. The mass of the total aged particles, i.e., particle mass measured downstream of the PAM chamber, was 6-268 times as high as the mass of the emitted primary exhaust particles. The secondary organic aerosol (SOA) formation potential was measured to be 9-20 mg kgfuel-1. The total aged particles mainly consisted of organic matter, nitrate, sulfate and ammonium, with the fractions depending on exhaust after-treatment and the engine parameters used. Also, the volatility, composition and concentration of the total aged particles were found to depend on the engine operating mode, catalyst temperature and catalyst type. For example, a high catalyst temperature promoted the formation of sulfate particles, whereas a low catalyst temperature promoted nitrate formation. However, in particular, the concentration of nitrate needed a long time to stabilize - more than half an hour - which complicated the conclusions but also indicates the sensitivity of nitrate measurements on experimental parameters such as emission source and system temperatures. Sulfate was measured to have the highest evaporation temperature, and nitrate had the lowest. The evaporation temperature of ammonium depended on the fractions of nitrate and sulfate in the particles. The average volatility of the total aged particles was measured to be lower than that of primary particles, indicating better stability of the aged natural gas engine-emitted aerosol in the atmosphere. According to the results of this study, the exhaust of a natural gas engine equipped with a catalyst forms secondary aerosol when the atmospheric ages in a PAM chamber are several days long. The secondary aerosol matter has different physical characteristics from those of primary particulate emissions.

Attitudes and Aspirations Regarding Engineering among Chinese Secondary School Students: Comparisons between Industrialising and Post-Industrial Geo-Engineering Regions of Mainland China and Hong Kong

ERIC Educational Resources Information Center

Kutnick, Peter; Zhu, Zhiyong; Chan, Cecilia; Chan, Rosanna Yuen-Yan; Lee, Betty Pok-Yee; Lai, Veronica Ka Wai

2018-01-01

School-based pipelines/routes for university and technical engineering education are recognised as important for economic development and the high-school years are critical for shaping students' career aspirations and attitudes. This study examined a range of attitudes/experiences on the aspirations of secondary students to pursue engineering…

Expression of a maize Myb transcription factor driven by a putative silk-specific promoter significantly enhances resistance to Helicoverpa zea in transgenic maize.

PubMed

Johnson, Eric T; Berhow, Mark A; Dowd, Patrick F

2007-04-18

Hi II maize (Zea mays) plants were engineered to express maize p1 cDNA, a Myb transcription factor, controlled by a putative silk specific promoter, for secondary metabolite production and corn earworm resistance. Transgene expression did not enhance silk color, but about half of the transformed plant silks displayed browning when cut, which indicated the presence of p1-produced secondary metabolites. Levels of maysin, a secondary metabolite with insect toxicity, were highest in newly emerged browning silks. The insect resistance of transgenic silks was also highest at emergence, regardless of maysin levels, which suggests that other unidentified p1-induced molecules likely contributed to larval mortality. Mean survivor weights of corn earworm larvae fed mature browning transgenic silks were significantly lower than weights of those fed mature nonbrowning transgenic silks. Some transgenic pericarps browned with drying and contained similar molecules found in pericarps expressing a dominant p1 allele, suggesting that the promoter may not be silk-specific.

Study of turbine bypass remote augmentor lift system for V/STOL aircraft

NASA Technical Reports Server (NTRS)

Sheridan, A. E.

1985-01-01

The airframe design and engine/aircraft integration were emphasized in a NASA comparative study of turbofan and turbine bypass engine (TBE) with remote augmentor lift systems (RALS) for supersonic V/STOL aircraft. Functional features of the TBE are reviewed, noting the enhanced cycle efficiency and reduced afterbody drag compared to the turbojets. The present studies examied performance levels for aircraft with fleet defense and secondary anti-surface warfare roles, carrying AMRAAM and AIM missiles. TBE engine cycles were configured for hover and up-and-away flight from deck launch, and all tests were done from a conceptual design viewpoint. The results indicate that the TBE-RALS is superior to turbofan-RALS aircraft in both gross take-off weight and life cycle cost.

The Engineering Design Process: Conceptions Along the Learning-to-Teach Continuum

NASA Astrophysics Data System (ADS)

Iveland, Ashley

In this study, I sought to identify differences in the views and understandings of engineering design among individuals along the learning-to-teach continuum. To do so, I conducted a comprehensive review of literature to determine the various aspects of engineering design described in the fields of professional engineering and engineering education. Additionally, I reviewed literature on the methods used in teaching engineering design at the secondary (grade 7-12) level - to describe the various models used in classrooms, even before the implementation of the Next Generation Science Standards (NGSS Lead States, 2013). Last, I defined four groups along the learning-to-teach continuum: prospective, preservice, and practicing teachers, as well as teacher educators. The context of this study centered around a California public university, including an internship program where undergraduates engaged with practicing mentor teachers in science and engineering teaching at local high schools, and a teacher education program where secondary science preservice teachers and the teacher educators who taught them participated. Interviews were conducted with all participants to gain insights into their views and understandings of engineering design. Prospective and preservice teachers were interviewed multiple times throughout the year and completed concept maps of the engineering design process multiple times as well; practicing teachers and teacher educators were interviewed once. Three levels of analyses were conducted. I identified 30 aspects of engineering discussed by participants. Through phenomenographic methods, I also constructed six conceptual categories for engineering design to organize those aspects most commonly discussed. These categories were combined to demonstrate a participant's view of engineering design (e.g., business focused, human centered, creative, etc.) as well as their complexity of understanding of engineering design overall (the more categories their ideas fit within, the more complex their understanding was thought to be). I found that the most commonly referenced aspects of engineering design were in line with the three main dimensions described in the Next Generation Science Standards (NGSS Lead States, 2013). I also found that the practicing teacher participants overall conveyed the most complex and integrated understandings of engineering design, with the undergraduate, prospective teachers not far behind. One of the most important factors related to a more integrated understanding of engineering design was having formal engineering experience, especially in the form of conducting engineering research or having been a professional engineer. Further, I found that female participants were more likely than their male counterparts to view engineering as having a human element--recognizing the need to collaborate with others throughout the process and the need to think about the potential user of the product the engineer is solving the problem for. These findings suggest that prior experience with engineering, and not experience in the classroom or with engineering education, tends to lead to a deeper, more authentic view of engineering. Finally, I close with a discussion of the overall findings, limitations of the study, potential implications, and future work.

Examining Gender Inequality In A High School Engineering Course.

PubMed

Riegle-Crumb, Catherine; Moore, Chelsea

2013-01-01

This paper examines gender inequality within the context of an upper-level high school engineering course recently offered in Texas. Data was collected from six high schools that serve students from a variety of backgrounds. Among the almost two hundred students who enrolled in this challenge-based engineering course, females constituted a clear minority, comprising only a total of 14% of students. Quantitative analyses of surveys administered at the beginning of the school year (Fall 2011) revealed statistically significant gender gaps in personal attitudes towards engineering and perceptions of engineering climate. Specifically, we found that compared to males, females reported lower interest in and intrinsic value for engineering, and expressed less confidence in their engineering skills. Additionally, female students felt that the classroom was less inclusive and viewed engineering occupations as less progressive. Gender disparities on all of these measures did not significantly decrease by the end of the school year (Spring 2012). Findings suggest that efforts to increase the representation of women in the engineering pipeline via increasing exposure in secondary education must contend not only with obstacles to recruiting high school girls into engineering courses, but must also work to remedy gender differences in engineering attitudes within the classroom.

Examining Gender Inequality In A High School Engineering Course

PubMed Central

Moore, Chelsea

2014-01-01

This paper examines gender inequality within the context of an upper-level high school engineering course recently offered in Texas. Data was collected from six high schools that serve students from a variety of backgrounds. Among the almost two hundred students who enrolled in this challenge-based engineering course, females constituted a clear minority, comprising only a total of 14% of students. Quantitative analyses of surveys administered at the beginning of the school year (Fall 2011) revealed statistically significant gender gaps in personal attitudes towards engineering and perceptions of engineering climate. Specifically, we found that compared to males, females reported lower interest in and intrinsic value for engineering, and expressed less confidence in their engineering skills. Additionally, female students felt that the classroom was less inclusive and viewed engineering occupations as less progressive. Gender disparities on all of these measures did not significantly decrease by the end of the school year (Spring 2012). Findings suggest that efforts to increase the representation of women in the engineering pipeline via increasing exposure in secondary education must contend not only with obstacles to recruiting high school girls into engineering courses, but must also work to remedy gender differences in engineering attitudes within the classroom. PMID:25568814

Evolution of Gender Differences in Post-Secondary Human Capital Investments: College Majors. Working Paper #03-11

ERIC Educational Resources Information Center

Gemici, Ahu; Wiswall, Matthew

2011-01-01

Over the past 40 years, the level of human capital investments has changed substantially for men and women. Changes in the intensive margin of college major selection have been also been substantial, as the number of graduates in humanities, social science, and teaching has declined, and the number in science, engineering, and business has…

Military Curricula for Vocational & Technical Education. General Purpose Vehicle Mechanic. Blocks I and II, 8-9.

ERIC Educational Resources Information Center

Ohio State Univ., Columbus. National Center for Research in Vocational Education.

This plan of instruction, lesson plans, student handouts, and programed texts for a secondary-postsecondary level course in engine mechanics is one of a number of military-developed curriculum packages selected for adaptation to vocational instruction and curriculum development in a civilian setting. It is the first of a four-part course (see Note…

Military Curricula for Vocational & Technical Education. General Purpose Vehicle Mechanic, Blocks VI & VII, 8-12.

ERIC Educational Resources Information Center

Ohio State Univ., Columbus. National Center for Research in Vocational Education.

This plan of instruction, lesson plans, student study guides, and programed texts for a secondary-postsecondary level course in engine mechanics is one of a number of military-developed curriculum packages selected for adaptation to vocational instruction and curriculum development in a civilian setting. It is the fourth of a four-part course (see…

Engineering the formation of secondary building blocks within hollow interiors.

PubMed

Li, Xiaobo; Liu, Xiao; Ma, Yi; Li, Mingrun; Zhao, Jiao; Xin, Hongchuan; Zhang, Lei; Yang, Yan; Li, Can; Yang, Qihua

2012-03-15

Secondary building blocks within the cavities of primary silica-architecture building blocks are successfully engineered. The immobilized surfactant directs the selective dissolution and reassembly of dissolved silicate species for the formation of secondary building blocks (hollow nanospheres/nanorods; see figure). Supported TiO(2) on nanostructures with multilevel interiors is shown to exhibit significantly enhanced activity in photocatalytic H(2) production. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Composition and sources of fine particulate matter across urban and rural sites in the Midwestern United States

PubMed Central

Kundu, Shuvashish; Stone, Elizabeth. A.

2014-01-01

The composition and sources of fine particulate matter (PM2.5) were investigated in rural and urban locations in Iowa, located in the agricultural and industrial Midwestern United States from April 2009 to December 2012. Major chemical contributors to PM2.5 mass were sulfate, nitrate, ammonium, and organic carbon. Non-parametric statistical analyses demonstrated that the two rural sites had significantly enhanced levels of crustal materials (Si, Al) driven by agricultural activities and unpaved roads. Meanwhile, the three urban areas had enhanced levels of secondary aerosol (nitrate, sulfate, and ammonium) and combustion (organic and elemental carbon). The heavily industrialized Davenport site had significantly higher levels of PM2.5 and trace metals (Fe, Pb, Zn), demonstrating the important local impact of industrial point sources on air quality. Sources of PM2.5 were evaluated by the multi-variant positive matrix factorization (PMF) source apportionment model. For each individual site, seven to nine factors were identified: secondary sulfate (accounting for 29–30% of PM2.5), secondary nitrate (17–24%), biomass burning (9–21%), gasoline combustion (6–16), diesel combustion (3–9%), dust (6–11%), industry (0.4–5%) and winter salt (2–6%). Source contributions demonstrated a clear urban enhancement in PM2.5 from gasoline engines (by a factor of 1.14) and diesel engines (by a factor of 2.3), which is significant due to the well-documented negative health impacts of vehicular emissions. This study presents the first source apportionment results from the state of Iowa and is broadly applicable to understanding the differences in anthropogenic and natural sources in the urban-rural continuum of particle air pollution. PMID:24736797

Effect of Installation of Mixer/Ejector Nozzles on the Core Flow Exhaust of High-Bypass-Ratio Turbofan Engines

NASA Technical Reports Server (NTRS)

Harrington, Douglas E.

1998-01-01

The aerospace industry is currently investigating the effect of installing mixer/ejector nozzles on the core flow exhaust of high-bypass-ratio turbofan engines. This effort includes both full-scale engine tests at sea level conditions and subscale tests in static test facilities. Subscale model tests are to be conducted prior to full-scale testing. With this approach, model results can be analyzed and compared with analytical predications. Problem areas can then be identified and design changes made and verified in subscale prior to committing to any final design configurations for engine ground tests. One of the subscale model test programs for the integrated mixer/ejector development was a joint test conducted by the NASA Lewis Research Center and Pratt & Whitney Aircraft. This test was conducted to study various mixer/ejector nozzle configurations installed on the core flow exhaust of advanced, high-bypass-ratio turbofan engines for subsonic, commercial applications. The mixer/ejector concept involves the introduction of largescale, low-loss, streamwise vortices that entrain large amounts of secondary air and rapidly mix it with the primary stream. This results in increased ejector pumping relative to conventional ejectors and in more complete mixing within the ejector shroud. The latter improves thrust performance through the efficient energy exchange between the primary and secondary streams. This experimental program was completed in April 1997 in Lewis' CE-22 static test facility. Variables tested included the nozzle area ratio (A9/A8), which ranged from 1.6 to 3.0. This ratio was varied by increasing or decreasing the nozzle throat area, A8. Primary nozzles tested included both lobed mixers and conical primaries. These configurations were tested with and without an outer shroud, and the shroud position was varied by inserting spacers in it. In addition, data were acquired with and without secondary flow.

What Do K-12 Students Feel When Dealing with Technology and Engineering Issues? Gardner's Multiple Intelligence Theory Implications in Technology Lessons for Motivating Engineering Vocations at Spanish Secondary School

ERIC Educational Resources Information Center

Sánchez-Martín, Jesús; Álvarez-Gragera, García J.; Dávila-Acedo, M. Antonia; Mellado, Vicente

2017-01-01

The interest on engineering and scientific studies can be raised up even from the early years of academic instructional process. This vocation may be linked to emotions and aptitudes towards technological education. Particularly, students get in touch with these technological issues (namely STEM) during the Compulsory Secondary Education in Spain…

An engine trade study for a supersonic STOVL fighter-attack aircraft, volume 1

NASA Technical Reports Server (NTRS)

Beard, B. B.; Foley, W. H.

1982-01-01

The best main engine for an advanced STOVL aircraft flight demonstrator was studied. The STOVL aircraft uses ejectors powered by engine bypass flow together with vectored core exhaust to achieve vertical thrust capability. Bypass flow and core flow are exhausted through separate nozzles during wingborne flight. Six near term turbofan engines were examined for suitability for this aircraft concept. Fan pressure ratio, thrust split between bypass and core flow, and total thrust level were used to compare engines. One of the six candidate engines was selected for the flight demonstrator configuration. Propulsion related to this aircraft concept was studied. A preliminary candidate for the aircraft reaction control system for hover attitude control was selected. A mathematical model of transfer of bypass thrust from ejectors to aft directed nozzle during the transition to wingborne flight was developed. An equation to predict ejector secondary air flow rate and ram drag is derived. Additional topics discussed include: nozzle area control, ejector to engine inlet reingestion, bypass/core thrust split variation, and gyroscopic behavior during hover.

Future engineers: the intrinsic technology motivation of secondary school pupils

NASA Astrophysics Data System (ADS)

Jones, Lewis C. R.; McDermott, Hilary J.; Tyrer, John R.; Zanker, Nigel P.

2018-07-01

The supply of students motivated to study engineering in higher education is critical to the sector. Results are presented from the 'Mindsets STEM Enhancement Project'. Fifty-seven new resources packs, designed to improve STEM education in Design and Technology, were given to schools across London. A modified Intrinsic Motivation Inventory questionnaire measured pupils' (n = 458) motivation towards technology. The results show that although pupils have positive reactions to the technology content within Design and Technology lessons, the type of STEM resources and lessons created through the project had made no significant difference on pupils' interest/enjoyment towards technology. This suggests stand-alone resources do not improve pupil motivation. The impact of this work to engineering higher education is that the existing levels and the inability to improve pupil motivation in technology at school could be a factor affecting the pursuit of a technology or engineering related education or career.

A gene stacking approach leads to engineered plants with highly increased galactan levels in Arabidopsis

DOE PAGES

Gondolf, Vibe M.; Stoppel, Rhea; Ebert, Berit; ...

2014-12-10

Background: Engineering of plants with a composition of lignocellulosic biomass that is more suitable for downstream processing is of high interest for next-generation biofuel production. Lignocellulosic biomass contains a high proportion of pentose residues, which are more difficult to convert into fuels than hexoses. Therefore, increasing the hexose/pentose ratio in biomass is one approach for biomass improvement. A genetic engineering approach was used to investigate whether the amount of pectic galactan can be specifically increased in cell walls of Arabidopsis fiber cells, which in turn could provide a potential source of readily fermentable galactose. Results: First it was tested ifmore » overexpression of various plant UDP-glucose 4-epimerases (UGEs) could increase the availability of UDP-galactose and thereby increase the biosynthesis of galactan. Constitutive and tissue-specific expression of a poplar UGE and three Arabidopsis UGEs in Arabidopsis plants could not significantly increase the amount of cell wall bound galactose. We then investigated co-overexpression of AtUGE2 together with the β-1,4-galactan synthase GalS1. Co-overexpression of AtUGE2 and GalS1 led to over 80% increase in cell wall galactose levels in Arabidopsis stems, providing evidence that these proteins work synergistically. Furthermore, AtUGE2 and GalS1 overexpression in combination with overexpression of the NST1 master regulator for secondary cell wall biosynthesis resulted in increased thickness of fiber cell walls in addition to the high cell wall galactose levels. Immunofluorescence microscopy confirmed that the increased galactose was present as β-1,4-galactan in secondary cell walls. Conclusions: This approach clearly indicates that simultaneous overexpression of AtUGE2 and GalS1 increases the cell wall galactose to much higher levels than can be achieved by overexpressing either one of these proteins alone. Moreover, the increased galactan content in fiber cells while improving the biomass composition had no impact on plant growth and development and hence on the overall biomass amount. Thus, we could show that the gene stacking approach described here is a promising method to engineer advanced feedstocks for biofuel production.« less

Engineering and Industrial Fields. Revised Summary Report: Technical Employment in Northeast Florida.

ERIC Educational Resources Information Center

Baker, William E.; And Others

The document is one of five summary reports, all part of a Pre-Technical Curriculum Planning Project for secondary students who aspire to technical employment or post secondary technical education. This report represents the results of an assessment of the northeast Florida area's technical occupations in engineering and industrial fields. A…

Photochemical processing of diesel fuel emissions as a large secondary source of isocyanic acid (HNCO)

NASA Astrophysics Data System (ADS)

Link, M. F.; Friedman, B.; Fulgham, R.; Brophy, P.; Galang, A.; Jathar, S. H.; Veres, P.; Roberts, J. M.; Farmer, D. K.

2016-04-01

Isocyanic acid (HNCO) is a well-known air pollutant that affects human health. Biomass burning, smoking, and combustion engines are known HNCO sources, but recent studies suggest that secondary production in the atmosphere may also occur. We directly observed photochemical production of HNCO from the oxidative aging of diesel exhaust during the Diesel Exhaust Fuel and Control experiments at Colorado State University using acetate ionization time-of-flight mass spectrometry. Emission ratios of HNCO were enhanced, after 1.5 days of simulated atmospheric aging, from 50 to 230 mg HNCO/kg fuel at idle engine operating conditions. Engines operated at higher loads resulted in less primary and secondary HNCO formation, with emission ratios increasing from 20 to 40 mg HNCO/kg fuel under 50% load engine operating conditions. These results suggest that photochemical sources of HNCO could be more significant than primary sources in urban areas.

Design and analysis report for the flight weight 20-inch Columbium secondary nozzle for the RL10 engine

NASA Technical Reports Server (NTRS)

Castro, J. H.

1989-01-01

Pratt & Whitney (P and W) is currently under contract to NASA-LeRC for a multi-year program to evaluate the feasibility of the RL10-IIB/IIC engine models and the various improvements which broaden the engine capabilities and range of applications. The features being evaluated include the operation of the RL10 engine at low thrust levels and/or high mixture ratio levels and the addition of a high area ratio (250:1) translating nozzle to the engine to increase its specific impulse while shortening the installed engine length. The translating nozzle for the RL10-IIB/IIC engine is approximately 55 inches long with an exit plane diameter of 71 inches and an inlet plane diameter of 40 inches. This report documents the design and analysis work done investigating a small subscale Columbium nozzle which could be built and tested to provide findings which then could be incorporated into the high area ratio nozzle final design for the RL10-IIB/IIC engine. This report documents the design and analysis work done investigating a small subscale Columbium nozzle which could be built and tested to provide findings which then could be incorporated into the high area ratio nozzle final design for the RL10-IIB/IIC engine. The length of the subscale nozzle is 20 in.; its exit diameter is 46 in. With the nozzle in the stowed position, an RL10A-3-3A engine system is 70 inches long (Area Ratio = 61:1); with the nozzle deployed the engine length and area ratio are increased to 90 inches and 83:1 respectively. The increase in area ratio provides a calculated increase of 7 + or - 1 second of specific impulse.

Aluminum/hydrocarbon gel propellants: An experimental and theoretical investigation of secondary atomization and predicted rocket engine performance

NASA Astrophysics Data System (ADS)

Mueller, Donn Christopher

1997-12-01

Experimental and theoretical investigations of aluminum/hydrocarbon gel propellant secondary atomization and its potential effects on rocket engine performance were conducted. In the experimental efforts, a dilute, polydisperse, gel droplet spray was injected into the postflame region of a burner and droplet size distributions was measured as a function of position above the burner using a laser-based sizing/velocimetry technique. The sizing/velocimetry technique was developed to measure droplets in the 10-125 mum size range and avoids size-biased detection through the use of a uniformly illuminated probe volume. The technique was used to determine particle size distributions and velocities at various axial locations above the burner for JP-10, and 50 and 60 wt% aluminum gels. Droplet shell formation models were applied to aluminum/hydrocarbon gels to examine particle size and mass loading effects on the minimum droplet diameter that will permit secondary atomization. This diameter was predicted to be 38.1 and 34.7 mum for the 50 and 60 wt% gels, which is somewhat greater than the experimentally measured 30 and 25 mum diameters. In the theoretical efforts, three models were developed and an existing rocket code was exercised to gain insights into secondary atomization. The first model was designed to predict gel droplet properties and shell stresses after rigid shell formation, while the second, a one-dimensional gel spray combustion model was created to quantify the secondary atomization process. Experimental and numerical comparisons verify that secondary atomization occurs in 10-125 mum diameter particles although an exact model could not be derived. The third model, a one-dimensional gel-fueled rocket combustion chamber, was developed to evaluate secondary atomization effects on various engine performance parameters. Results show that only modest secondary atomization may be required to reduce propellant burnout distance and radiation losses. A solid propellant engine code was employed to estimate nozzle two-phase flow losses and engine performance for upper-stage and booster missions (3-6% and 2-3%, respectively). Given these losses and other difficulties, metallized gel propellants may be impractical in high-expansion ratio engines. Although uncertainties remain, it appears that performance gains will be minimal in gross-weight limited missions, but that significant gains may arise in volume-limited missions.

Engineering Related Technology: A Laboratory and Curriculum Design for the Newly Emerging Technology of Pollution-Corrosion Measurement and Control. Final Report.

ERIC Educational Resources Information Center

Shields, F. K.; And Others

In order to meet the educational needs for a separate curriculum at the secondary level for technological training related to pollution and corrosion measurement and control, a 3-year, 1080-hour vocational program was developed for use in an area vocational high school. As one of four programs in the technology careers area, this curriculum design…

Survey of Secondary School Principals: Building Engineer Reporting Line Change. Report No. 8425.

ERIC Educational Resources Information Center

Farber, Irvin J.; Lytle, James H.

This paper reports the results of a questionnaire distributed to all Philadelphia secondary school principals (with returns from 68 percent), eliciting their reactions to various aspects of the transfer to them of line authority for building engineers. Responses indicate that the process of assuming supervisory responsibility was not yet complete,…

Heterologous expression of oxytetracycline biosynthetic gene cluster in Streptomyces venezuelae WVR2006 to improve production level and to alter fermentation process.

PubMed

Yin, Shouliang; Li, Zilong; Wang, Xuefeng; Wang, Huizhuan; Jia, Xiaole; Ai, Guomin; Bai, Zishang; Shi, Mingxin; Yuan, Fang; Liu, Tiejun; Wang, Weishan; Yang, Keqian

2016-12-01

Heterologous expression is an important strategy to activate biosynthetic gene clusters of secondary metabolites. Here, it is employed to activate and manipulate the oxytetracycline (OTC) gene cluster and to alter OTC fermentation process. To achieve these goals, a fast-growing heterologous host Streptomyces venezuelae WVR2006 was rationally selected among several potential hosts. It shows rapid and dispersed growth and intrinsic high resistance to OTC. By manipulating the expression of two cluster-situated regulators (CSR) OtcR and OtrR and precursor supply, the OTC production level was significantly increased in this heterologous host from 75 to 431 mg/l only in 48 h, a level comparable to the native producer Streptomyces rimosus M4018 in 8 days. This work shows that S. venezuelae WVR2006 is a promising chassis for the production of secondary metabolites, and the engineered heterologous OTC producer has the potential to completely alter the fermentation process of OTC production.

Standardized Curriculum for Diesel Engine Mechanics.

ERIC Educational Resources Information Center

Mississippi State Dept. of Education, Jackson. Office of Vocational, Technical and Adult Education.

Standardized curricula are provided for two courses for the secondary vocational education program in Mississippi: diesel engine mechanics I and II. The eight units in diesel engine mechanics I are as follows: orientation; shop safety; basic shop tools; fasteners; measurement; engine operating principles; engine components; and basic auxiliary…

A computer model for liquid jet atomization in rocket thrust chambers

NASA Astrophysics Data System (ADS)

Giridharan, M. G.; Lee, J. G.; Krishnan, A.; Yang, H. Q.; Ibrahim, E.; Chuech, S.; Przekwas, A. J.

1991-12-01

The process of atomization has been used as an efficient means of burning liquid fuels in rocket engines, gas turbine engines, internal combustion engines, and industrial furnaces. Despite its widespread application, this complex hydrodynamic phenomenon has not been well understood, and predictive models for this process are still in their infancy. The difficulty in simulating the atomization process arises from the relatively large number of parameters that influence it, including the details of the injector geometry, liquid and gas turbulence, and the operating conditions. In this study, numerical models are developed from first principles, to quantify factors influencing atomization. For example, the surface wave dynamics theory is used for modeling the primary atomization and the droplet energy conservation principle is applied for modeling the secondary atomization. The use of empirical correlations has been minimized by shifting the analyses to fundamental levels. During applications of these models, parametric studies are performed to understand and correlate the influence of relevant parameters on the atomization process. The predictions of these models are compared with existing experimental data. The main tasks of this study were the following: development of a primary atomization model; development of a secondary atomization model; development of a model for impinging jets; development of a model for swirling jets; and coupling of the primary atomization model with a CFD code.

Assessment of Knowledge and Competences in Agricultural Engineering Acquired by the Senior Secondary School Students for Farm Mechanisation

ERIC Educational Resources Information Center

Ndem, Joseph; Ogba, Ernest; Egbe, Benjamin

2015-01-01

This study was designed to assess the agricultural engineering knowledge and competencies acquired by the senior secondary students for farm mechanization in technical colleges in Ebonyi state of Nigeria. A survey research design was adopted for the study. Three research questions and two null hypotheses guided the study. The population of the…

Toward Systems Metabolic Engineering of Streptomycetes for Secondary Metabolites Production.

PubMed

Robertsen, Helene Lunde; Weber, Tilmann; Kim, Hyun Uk; Lee, Sang Yup

2018-01-01

Streptomycetes are known for their inherent ability to produce pharmaceutically relevant secondary metabolites. Discovery of medically useful, yet novel compounds has become a great challenge due to frequent rediscovery of known compounds and a consequent decline in the number of relevant clinical trials in the last decades. A paradigm shift took place when the first whole genome sequences of streptomycetes became available, from which silent or "cryptic" biosynthetic gene clusters (BGCs) were discovered. Cryptic BGCs reveal a so far untapped potential of the microorganisms for the production of novel compounds, which has spurred new efforts in understanding the complex regulation between primary and secondary metabolism. This new trend has been accompanied with development of new computational resources (genome and compound mining tools), generation of various high-quality omics data, establishment of molecular tools, and other strain engineering strategies. They all come together to enable systems metabolic engineering of streptomycetes, allowing more systematic and efficient strain development. In this review, the authors present recent progresses within systems metabolic engineering of streptomycetes for uncovering their hidden potential to produce novel compounds and for the improved production of secondary metabolites. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pulse detonation engines and components thereof

NASA Technical Reports Server (NTRS)

Tangirala, Venkat Eswarlu (Inventor); Rasheed, Adam (Inventor); Vandervort, Christian Lee (Inventor); Dean, Anthony John (Inventor)

2009-01-01

A pulse detonation engine comprises a primary air inlet; a primary air plenum located in fluid communication with the primary air inlet; a secondary air inlet; a secondary air plenum located in fluid communication with the secondary air inlet, wherein the secondary air plenum is substantially isolated from the primary air plenum; a pulse detonation combustor comprising a pulse detonation chamber, wherein the pulse detonation chamber is located downstream of and in fluid communication with the primary air plenum; a coaxial liner surrounding the pulse detonation combustor defining a cooling plenum, wherein the cooling plenum is in fluid communication with the secondary air plenum; an axial turbine assembly located downstream of and in fluid communication with the pulse detonation combustor and the cooling plenum; and a housing encasing the primary air plenum, the secondary air plenum, the pulse detonation combustor, the coaxial liner, and the axial turbine assembly.

A Theoretical Evaluation of Secondary Atomization Effects on Engine Performance for Aluminum Gel Propellants

NASA Technical Reports Server (NTRS)

Mueller, D. C.; Turns, S. R.

1994-01-01

A one-dimensional model of a gel-fueled rocket combustion chamber has been developed. This model includes the processes of liquid hydrocarbon burnout, secondary atomization. aluminum ignition, and aluminum combustion. Also included is a model of radiative heat transfer from the solid combustion products to the chamber walls. Calculations indicate that only modest secondary atomization is required to significantly reduce propellant burnout distances, aluminum oxide residual size and radiation heat wall losses. Radiation losses equal to approximately 2-13 percent of the energy released during combustion were estimated. A two-dimensional, two-phase nozzle code was employed to estimate radiation and nozzle two-phase flow effects on overall engine performance. Radiation losses yielded a 1 percent decrease in engine I(sub sp). Results also indicate that secondary atomization may have less effect on two-phase losses than it does on propellant burnout distance and no effect if oxide particle coagulation and shear induced droplet breakup govern oxide particle size. Engine I(sub sp) was found to decrease from 337.4 to 293.7 seconds as gel aluminum mass loading was varied from 0-70 wt percent. Engine I(sub sp) efficiencies, accounting for radiation and two-phase flow effects, on the order of 0.946 were calculated for a 60 wt percent gel, assuming a fragmentation ratio of 5.

The Shock and Vibration Bulletin. Part 1. Summaries of Presented Papers

DTIC Science & Technology

1973-10-01

Mechanical Engineering Department, University of the Negev , Israel It was recently observed [1] that during metal deformation a transient e.m.f. is...turn radiate noise. In many cases, significant contributions can be made toward solution of the overall problem by Uaing properly optimized damping...delineate the role of these resonant sources of secondary sound radiation in a USAF MAC HH-53 helicopter as regards internal cabin noise level (b

Laboratory tests on heat treatment of ballast water using engine waste heat.

PubMed

Balaji, Rajoo; Lee Siang, Hing; Yaakob, Omar; Koh, Kho King; Adnan, Faizul Amri Bin; Ismail, Nasrudin Bin; Ahmad, Badruzzaman Bin; Ismail, Mohd Arif Bin; Wan Nik, W B

2018-05-01

Waste heat recovery from shipboard machineries could be a potential source for heat treatment of ballast water. Similar to a shipboard schematic arrangement, a laboratory-scale engine-heat exchanger set-up harvesting waste heat from jacket water and exhaust gases was erected to test the level of species' mortalities. Mortalities were also assessed under experimental conditions for cultured and natural plankton communities at laboratory level. Effect of pump impellers on species' mortalities were also tested. Exposures between 60°C and 70°C for 60 sec resulted in 80-100% mortalities. Mortalities due to pump impeller effects were observed in the range of 70-100% for zooplankton. On the laboratory-scale arrangement, >95% mortalities of phytoplankton, zooplankton and bacteria were recorded. It was demonstrated that the temperature of tropical sea waters used as secondary coolant can be raised to cause species' mortalities, employing engine exhaust gases. The results also indicated that pump impeller effects will enhance species' mortalities. The limitations of the shipboard application of this method would be the large ballast volumes, flow rates and time for treatment.

Interactive physics apparatus: influence on interest of secondary school students in pursuing a career path in science, technology, engineering and mathematics (STEM)

NASA Astrophysics Data System (ADS)

Lubrica, Joel V.; Abiasen, Jovalson T.; Dolipas, Bretel B.; Ramos, Jennifer Lyn S.

2017-01-01

In this article, we present results of our endeavours as physics educators to facilitate and support pedagogical change and development in the educational system of a developing country, the Philippines. We have discovered that the interaction of junior high school (years 7-10) students with physics apparatus can influence students’ interest in pursuing a career in science, technology, engineering and mathematics (STEM). This assertion stems from self-reports of students who gave their views immediately after their exposure to interactive apparatus in their own school, outside of their usual lessons. Participants claimed that their interest in following a STEM career path was ‘greatly increased’ due to their exposure to these apparatus. This was true even for students who were intending to take a non-STEM career path. Thus, we recommend that, in settings that have constraints involving access to practical equipment, ways to introduce school level interactive physics apparatus to secondary school students be conducted in order to attract more students towards STEM courses. Possibly, policies encouraging this type of exposure should also be formulated.

Turbomachine Sealing and Secondary Flows. Part 1; Review of Sealing Performance, Customer, Engine Designer, and Research Issues

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Steinetz, B. M.; Braun, M. J.

2004-01-01

Although forces outside our control shape our industry, turbomachine sealing research, design, and customer agendas established in 1978 by Ludwig, Campbell, and Smith in terms of specific fuel consumption and performance remain as objectives today. Advances have been made because failures of the space shuttle main engine turbomachinery ushered in a new understanding of sealing in high-power-density systems. Further, it has been shown that changes in sealing, especially for high-pressure rotors, dramatically change the performance of the entire engine or turbomachine. Maintaining seal leakages and secondary flows within engine design specifications remains the most efficient and cost effective way to enhance performance and minimize maintenance costs. This three-part review summarizes experiences, ideas, successes, and failures by NASA and the U.S. aerospace industry in secondary flow management in advanced turbomachinery. Part 1 presents system sealing, part 2 system rotordynamics, and part 3 modeling, with some overlap of each part.

The MEOW lunar project for education and science based on concurrent engineering approach

NASA Astrophysics Data System (ADS)

Roibás-Millán, E.; Sorribes-Palmer, F.; Chimeno-Manguán, M.

2018-07-01

The use of concurrent engineering in the design of space missions allows to take into account in an interrelated methodology the high level of coupling and iteration of mission subsystems in the preliminary conceptual phase. This work presents the result of applying concurrent engineering in a short time lapse to design the main elements of the preliminary design for a lunar exploration mission, developed within ESA Academy Concurrent Engineering Challenge 2017. During this program, students of the Master in Space Systems at Technical University of Madrid designed a low cost satellite to find water on the Moon south pole as prospect of a future human lunar base. The resulting mission, The Moon Explorer And Observer of Water/Ice (MEOW) compromises a 262 kg spacecraft to be launched into a Geostationary Transfer Orbit as a secondary payload in the 2023/2025 time frame. A three months Weak Stability Boundary transfer via the Sun-Earth L1 Lagrange point allows for a high launch timeframe flexibility. The different aspects of the mission (orbit analysis, spacecraft design and payload) and possibilities of concurrent engineering are described.

Large-Scale Bi-Level Strain Design Approaches and Mixed-Integer Programming Solution Techniques

PubMed Central

Kim, Joonhoon; Reed, Jennifer L.; Maravelias, Christos T.

2011-01-01

The use of computational models in metabolic engineering has been increasing as more genome-scale metabolic models and computational approaches become available. Various computational approaches have been developed to predict how genetic perturbations affect metabolic behavior at a systems level, and have been successfully used to engineer microbial strains with improved primary or secondary metabolite production. However, identification of metabolic engineering strategies involving a large number of perturbations is currently limited by computational resources due to the size of genome-scale models and the combinatorial nature of the problem. In this study, we present (i) two new bi-level strain design approaches using mixed-integer programming (MIP), and (ii) general solution techniques that improve the performance of MIP-based bi-level approaches. The first approach (SimOptStrain) simultaneously considers gene deletion and non-native reaction addition, while the second approach (BiMOMA) uses minimization of metabolic adjustment to predict knockout behavior in a MIP-based bi-level problem for the first time. Our general MIP solution techniques significantly reduced the CPU times needed to find optimal strategies when applied to an existing strain design approach (OptORF) (e.g., from ∼10 days to ∼5 minutes for metabolic engineering strategies with 4 gene deletions), and identified strategies for producing compounds where previous studies could not (e.g., malate and serine). Additionally, we found novel strategies using SimOptStrain with higher predicted production levels (for succinate and glycerol) than could have been found using an existing approach that considers network additions and deletions in sequential steps rather than simultaneously. Finally, using BiMOMA we found novel strategies involving large numbers of modifications (for pyruvate and glutamate), which sequential search and genetic algorithms were unable to find. The approaches and solution techniques developed here will facilitate the strain design process and extend the scope of its application to metabolic engineering. PMID:21949695

Large-scale bi-level strain design approaches and mixed-integer programming solution techniques.

PubMed

Kim, Joonhoon; Reed, Jennifer L; Maravelias, Christos T

2011-01-01

The use of computational models in metabolic engineering has been increasing as more genome-scale metabolic models and computational approaches become available. Various computational approaches have been developed to predict how genetic perturbations affect metabolic behavior at a systems level, and have been successfully used to engineer microbial strains with improved primary or secondary metabolite production. However, identification of metabolic engineering strategies involving a large number of perturbations is currently limited by computational resources due to the size of genome-scale models and the combinatorial nature of the problem. In this study, we present (i) two new bi-level strain design approaches using mixed-integer programming (MIP), and (ii) general solution techniques that improve the performance of MIP-based bi-level approaches. The first approach (SimOptStrain) simultaneously considers gene deletion and non-native reaction addition, while the second approach (BiMOMA) uses minimization of metabolic adjustment to predict knockout behavior in a MIP-based bi-level problem for the first time. Our general MIP solution techniques significantly reduced the CPU times needed to find optimal strategies when applied to an existing strain design approach (OptORF) (e.g., from ∼10 days to ∼5 minutes for metabolic engineering strategies with 4 gene deletions), and identified strategies for producing compounds where previous studies could not (e.g., malate and serine). Additionally, we found novel strategies using SimOptStrain with higher predicted production levels (for succinate and glycerol) than could have been found using an existing approach that considers network additions and deletions in sequential steps rather than simultaneously. Finally, using BiMOMA we found novel strategies involving large numbers of modifications (for pyruvate and glutamate), which sequential search and genetic algorithms were unable to find. The approaches and solution techniques developed here will facilitate the strain design process and extend the scope of its application to metabolic engineering.

Power supply circuit for an ion engine sequentially operated power inverters

NASA Technical Reports Server (NTRS)

Cardwell, Jr., Gilbert I. (Inventor)

2000-01-01

A power supply circuit for an ion engine suitable for a spacecraft has a voltage bus having input line and a return line. The power supply circuit includes a pulse width modulation circuit. A plurality of bridge inverter circuits is coupled to the bus and the pulse width modulation circuit. The pulse width modulation circuit generates operating signals having a variable duty cycle. Each bridge inverter has a primary winding and a secondary winding. Each secondary winding is coupled to a rectifier bridge. Each secondary winding is coupled in series with another of the plurality of rectifier bridges.

Training the next generation of scientists: Modeling Infectious Disease and Water Quality of Montana Streams

NASA Astrophysics Data System (ADS)

Fytilis, N.; Wyman, S.; Lamb, R.; Stevens, L.; Kerans, B.; Rizzo, D. M.

2010-12-01

The University of Vermont College of Engineering and Mathematical Sciences and the Barrett Foundation have established a scholarship program for undergraduate students. The Barrett Scholarship program, aware of the importance of developing research quantitative and writing skills for undergraduate students, provides scholarships to outstanding undergraduate students for environmental engineering research projects. The intent is to help retain student interest early in their undergraduate engineering careers when few of their first or second year classes have little engineering or real-world application. We focus on one Barrett research project, derived from a NSF Biodiversity and Infectious Disease grant, because of the multiple disciplines (engineering, ecology, biology) and education levels (spanning secondary to graduate) involved. In this research, students across three departments at two universities (University of Vermont, Montana State University) and one independent high school (Vermont Commons School) formed a cohesive collaboration with faculty members to identify different worm taxa of T. Tubifex. Whirling disease has had a severe impact on the native population of salmonids in the upper Madison River MT, USA, resulting in the death of most fish that contract the parasite. T. Tubifex is the intermediate host for Myxobolus cerebralis, the parasite that causes whirling disease in salmonids. Samples collected from eight locations along the Madison River varied in the prevalence of whirling disease. The site-specific worm community structure has been measured and identified using molecular genetic probes and a taxonomic key to link worm communities to geochemical features (e.g. site elevation, slope, pH, conductivity, temperature, dissolved oxygen and percent of organic soil matter). Using a unique clustering algorithm, we group geochemical features to discriminate over a range of water quality gradients (i.e., “clean” to “dirty”). The link between water quality and the presence of these taxa is important in determining stream health. In addition, system dynamics software (STELLA) is used to model the non-linear relationships and feedback between worm prevalence and disease dynamics. These types of collaborations between engineers, biologists, field ecologists and geneticists from secondary, post-secondary and higher institutions proved useful in linking complex geochemical data, worm community structure and molecular genetics to develop the next-generation scientists and better understand disease dynamics.

Ignition and combustion characteristics of metallized propellants, phase 2

NASA Technical Reports Server (NTRS)

Mueller, D. C.; Turns, S. R.

1994-01-01

Experimental and analytical investigations focusing on aluminum/hydrocarbon gel droplet secondary atomization and its effects on gel-fueled rocket engine performance are being conducted. A single laser sheet sizing/velocimetry diagnostic technique, which should eliminate sizing bias in the data collection process, has been designed and constructed to overcome limitations of the two-color forward-scatter technique used in previous work. Calibration of this system is in progress and the data acquisition/validation code is being written. Narrow-band measurements of radiant emission, discussed in previous reports, will be used to determine if aluminum ignition has occurred in a gel droplet. A one-dimensional model of a gel-fueled rocket combustion chamber, described in earlier reports, has been exercised in conjunction with a two-dimensional, two-phase nozzle code to predict the performance of an aluminum/hydrocarbon fueled engine. Estimated secondary atomization effects on propellant burnout distance, condensed particle radiation losses to the chamber walls, and nozzle two phase flow losses are also investigated. Calculations indicate that only modest secondary atomization is required to significantly reduce propellant burnout distances, aluminum oxide residual size, and radiation heat losses. Radiation losses equal to approximately 2-13 percent of the energy released during combustion were estimated, depending on secondary atomization intensity. A two-dimensional, two-phase nozzle code was employed to estimate radiation and nozzle two phase flow effects on overall engine performance. Radiation losses yielded a one percent decrease in engine Isp. Results also indicate that secondary atomization may have less effect on two-phase losses than it does on propellant burnout distance and no effect if oxide particle coagulation and shear induced droplet breakup govern oxide particle size. Engine Isp was found to decrease from 337.4 to 293.7 seconds as gel aluminum mass loading was varied from 0-70 wt percent. Engine Isp efficiencies, accounting for radiation and two phase flow effects, on the order of 0.946 were calculated for a 60 wt percent gel, assuming a fragmentation ratio of five.

Reasons and motivations for the option of an engineering career in Portugal

NASA Astrophysics Data System (ADS)

Dias, Diana

2011-08-01

Towards the end of their secondary education, students face significant pressures in their decision about their career plan. These pressures are internal and external, personal and social, individual and from the reference group. This paper aims at understanding the reasons driving engineering students' choices, their perceived needs and aspirations. Moreover, it discusses how, in that process, students are constrained by family and friends and are conditioned by factors such as their socioeconomic and cultural background, employability prospects and gender. The construction of a career map/plan and the reasons and motivations for the option of an engineering career are reviewed, based on the qualitative analysis of students' discourses. The data indicate the relevance of several criteria such as social status, intelligence, gender, competences, values and interests in the construction of career aspirations. All these levels are highly influenced by self-esteem, which is closely related to the social value of training options and career paths.

Titan I propulsion system modeling and possible performance improvements

NASA Astrophysics Data System (ADS)

Giusti, Oreste

This thesis features the Titan I propulsion systems and offers data-supported suggestions for improvements to increase performance. The original propulsion systems were modeled both graphically in CAD and via equations. Due to the limited availability of published information, it was necessary to create a more detailed, secondary set of models. Various engineering equations---pertinent to rocket engine design---were implemented in order to generate the desired extra detail. This study describes how these new models were then imported into the ESI CFD Suite. Various parameters are applied to these imported models as inputs that include, for example, bi-propellant combinations, pressure, temperatures, and mass flow rates. The results were then processed with ESI VIEW, which is visualization software. The output files were analyzed for forces in the nozzle, and various results were generated, including sea level thrust and ISP. Experimental data are provided to compare the original engine configuration models to the derivative suggested improvement models.

Method and apparatus for reducing cold-phase emissions by utilizing oxygen-enriched intake air

DOEpatents

Poola, Ramesh B.; Sekar, Ramanujam R.; Stork, Kevin C.

1997-01-01

An oxygen-enriched air intake control system for an internal combustion engine includes air directing apparatus to control the air flow into the intake of the engine. During normal operation of the engine, ambient air flowing from an air filter of the engine flows through the air directing apparatus into the intake of the engine. In order to decrease the amount of carbon monoxide (CO) and hydrocarbon (HC) emissions that tend to be produced by the engine during a short period of time after the engine is started, the air directing apparatus diverts for a short period of time following the start up of the engine at least a portion of the ambient air from the air filter through a secondary path. The secondary path includes a selectively permeable membrane through which the diverted portion of the ambient air flows. The selectively permeable membrane separates nitrogen and oxygen from the diverted air so that oxygen enriched air containing from about 23% to 25% oxygen by volume is supplied to the intake of the engine.

Incorporating service-learning within engineering and technology education in secondary schools

NASA Astrophysics Data System (ADS)

Smiley, Craig L.

This study focuses the status of service-learning incorporated into the secondary engineering and technology classroom in the State of Indiana. Post-secondary engineering service-learning programs have been found to increase student interest in engineering to attract females into engineering (Coyle, Jamieson, & Oakes, 2005). Engineering, Design, and Development (EDD) is the capstone class of Project Lead The Way (PLTW) curriculum taught in many schools across Indiana, in which students design and develop a project that addresses an open-ended engineering problem. Of all the courses offered in the PLTW curriculum, this has the greatest potential for students to engage in a service-learning project, because the open-ended engineering problem could be used to help the community. A Likert-type survey was sent to the 62 secondary technology education teachers in Indiana who were certified to teach EDD during the 2011-2012 school year to identify the frequency at which the core components of service-learning, as identified by the National Service-Learning Clearinghouse (2006), were being implemented in the EDD curriculum. Fifteen teachers completed the survey by the end of the 2011-2012 academic calendar. Four of the 15 EDD teachers (27%) reported that a majority of their students' projects addressed a need in the community, and therefore were considered to be service-learning projects. The percentage of projects that were called service-learning projects by the respondents appeared to have a direct relationship with the total number of students enrolled in the PLTW program, and an inverse relationship with the number of years the teacher had been teaching technology education. Upon further study, only 2 of these EDD teachers (13%) were guiding students to collaborate with their community partner frequently enough to have an experience indicative of high quality service-learning according to the National Service-Learning Clearinghouse.

Renewable Microgrid STEM Education & Colonias Outreach Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

To provide Science, Technology, Engineering, and Math (STEM) outreach and education to secondary students to encourage them to select science and engineering as a career by providing an engineering-based problem-solving experience involving renewable energy systems such as photovoltaic (PV) panels or wind turbines. All public and private schools, community colleges, and vocational training programs would be eligible for participation. The Power Microgrids High School Engineering Experience used renewable energy systems (PV and wind) to provide a design capstone experience to secondary students. The objective for each student team was to design a microgrid for the student’s school using renewable energymore » sources under cost, schedule, performance, and risk constraints. The students then implemented their designs in a laboratory environment to evaluate the completeness of the proposed design, which is a unique experience even for undergraduate college students. This application-based program was marketed to secondary schools in the 28th Congressional District through the Texas Education Agency’s (TEA) Regional Service Centers. Upon application, TEES identified regionally available engineers to act as mentors and supervisors for the projects. Existing curriculum was modified to include microgrid and additional renewable technologies and was made available to the schools.« less

Calculation of Turbine Axial Thrust by Coupled CFD Simulations of the Main Flow Path and Secondary Cavity Flow in an SLI LOX Turbine

NASA Technical Reports Server (NTRS)

Dorney, D. J.; Marci, Bogdan; Tran, Ken; Sargent, Scott

2003-01-01

Each single reusable Space Launch Initiative (SLI) booster rocket is an engine operating at a record vacuum thrust level of over 730,000 Ibf using LOX and LH2. This thrust is more than 10% greater than that of the Delta IV rocket, resulting in relatively large LOX and LH2 turbopumps. Since the SLI rocket employs a staged combustion cycle the level of pressure is very high (thousands of psia). This high pressure creates many engineering challenges, including the balancing of axial-forces on the turbopumps. One of the main parameters in the calculation of the axial force is the cavity pressure upstream of the turbine disk. The flow in this cavity is very complex. The lack of understanding of this flow environment hinders the accurate prediction of axial thrust. In order to narrow down the uncertainty band around the actual turbine axial force, a coupled, unsteady computational methodology has been developed to simulate the interaction between the turbine main flow path and the cavity flow. The CORSAIR solver, an unsteady three- dimensional Navier-Stokes code for turbomachinery applications, was used to solve for both the main and the secondary flow fields. Turbine axial thrust values are presented in conjunction with the CFD simulation, together with several considerations regarding the turbine instrumentation for axial thrust estimations during test.

Computational Model Tracking Primary Electrons, Secondary Electrons, and Ions in the Discharge Chamber of an Ion Engine

NASA Technical Reports Server (NTRS)

Mahalingam, Sudhakar; Menart, James A.

2005-01-01

Computational modeling of the plasma located in the discharge chamber of an ion engine is an important activity so that the development and design of the next generation of ion engines may be enhanced. In this work a computational tool called XOOPIC is used to model the primary electrons, secondary electrons, and ions inside the discharge chamber. The details of this computational tool are discussed in this paper. Preliminary results from XOOPIC are presented. The results presented include particle number density distributions for the primary electrons, the secondary electrons, and the ions. In addition the total number of a particular particle in the discharge chamber as a function of time, electric potential maps and magnetic field maps are presented. A primary electron number density plot from PRIMA is given in this paper so that the results of XOOPIC can be compared to it. PRIMA is a computer code that the present investigators have used in much of their previous work that provides results that compare well to experimental results. PRIMA only models the primary electrons in the discharge chamber. Modeling ions and secondary electrons, as well as the primary electrons, will greatly increase our ability to predict different characteristics of the plasma discharge used in an ion engine.

mRNA secondary structure engineering of Thermobifida fusca endoglucanase (Cel6A) for enhanced expression in Escherichia coli.

PubMed

Ali, Imran; Asghar, Rehana; Ahmed, Sajjad; Sajjad, Muhammad; Tariq, Muhammad; Waheed Akhtar, M

2015-03-01

The sequence and structure of mRNA plays an important role in solubility and expression of the translated protein. To divulge the role of mRNA secondary structure and its thermodynamics in the expression level of the recombinant endoglucanase in Escherichia coli, 5'-end of the mRNA was thermodynamically optimized. Molecular engineering was done by introducing two silent synonymous mutations at positions +5 (UCU with UCC) and +7 (UUC with UUU) of the 5'-end of mRNA to relieve hybridization with ribosomal binding site. Two variants of glycoside hydrolase family six endoglucanase, wild type (cel6A.wt) and mutant (cel6A.mut) from Thermobifida fusca were expressed and characterized in E. coli using T7 promoter-based expression vector; pET22b(+). Enhanced expression level of engineered construct (Cel6A.mut) with ∆G = -2.7 kcal mol(-1)was observed. It showed up to ~45 % higher expression as compared to the wild type construct (Cel6A.wt) having ∆G = -7.8 kcal mol(-1) and ~25 % expression to the total cell proteins. Heterologous protein was purified by heating the recombinant E. coli BL21 (DE3) CodonPlus at 60 °C. The optimum pH for enzyme activity was six and optimum temperature was 60 °C. Maximum activity was observed 4.5 Umg(-1) on CMC. Hydrolytic activity was also observed on insoluble substrates, i.e. RAC (2.8 Umg(-1)), alkali treated bagass (1.7 Umg(-1)), filter paper (1.2 Umg(-1)) and BMCC (0.3 Umg(-1)). Metal ions affect endoglucanase activity in different ways. Only Fe(2+) exhibited 20.8 % stimulatory effects on enzyme activity. Enzyme activity was profoundly inhibited by Hg2(+) (91.8 %).

Identifying barriers to Science, Technology, Society and environment (STSE) educational goals and pedagogy in science education: A case study of UMASS Lowell undergraduate engineering

NASA Astrophysics Data System (ADS)

Phaneuf, Tiffany

The implementation of sustainable development in higher education is a global trend. Engineers, as gatekeepers of technological innovation, confront increasingly complex world issues ranging from economic and social to political and environmental. Recently, a multitude of government reports have argued that solving such complex problems requires changes in the pedagogy of engineering education, such as that prescribed by the Science, Technology, Society, and education (STS) movement that grew out of the environmental movement in the 70s. In STS students are engaged in the community by understanding that scientific progress is innately a sociopolitical process that involves dimensions of power, wealth and responsibility. United States accreditation criteria now demand "the broad education necessary to understand the impact of engineering solutions in a global, economic, environmental, and societal context" (ABET Engineering Accreditation Commission 2005). With such emphasis on STS education as necessary to address complex world issues, it is vital to assess the barriers in the traditional engineering curriculum that may inhibit the success of such educational reform. This study identifies barriers to STS goals and pedagogy in post secondary science education by using the Francis College of Engineering at UMASS Lowell as a single case study. The study draws on existing literature to develop a theoretical framework for assessing four hypothesized barriers to STS education in undergraduate engineering. Identification of barriers to STS education in engineering generates a critical reflection of post secondary science education and its role in preparing engineers to be active citizens in shaping a rapidly globalizing world. The study offers policy recommendations for enabling post secondary science education to incorporate STS education into its curriculum.

40 CFR 1068.262 - What are the provisions for temporarily exempting engines for shipment to secondary engine...

Code of Federal Regulations, 2011 CFR

2011-07-01

... manufacturers may finish assembly of partially complete engines in the following cases: (1) You obtain an engine... with the intent to modify it before it reaches the ultimate purchaser. (3) You obtain an engine with... of conformity but before the certificate's effective date. In this case, all the provisions of § 1068...

Where Is the Engineering I Applied For? A Longitudinal Study of Students' Transition into Higher Education Engineering, and Their Considerations of Staying or Leaving

ERIC Educational Resources Information Center

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

2016-01-01

This paper presents results from a qualitative longitudinal study of students' transition into higher education engineering. The study aims at comparing upper-secondary school students' expectations of engineering with their actual experiences when encountering the engineering programme. It explores how this encounter provides a platform for…

Thrust Augmented Nozzle for a Hybrid Rocket with a Helical Fuel Port

NASA Astrophysics Data System (ADS)

Marshall, Joel H.

A thrust augmented nozzle for hybrid rocket systems is investigated. The design lever-ages 3-D additive manufacturing to embed a helical fuel port into the thrust chamber of a hybrid rocket burning gaseous oxygen and ABS plastic as propellants. The helical port significantly increases how quickly the fuel burns, resulting in a fuel-rich exhaust exiting the nozzle. When a secondary gaseous oxygen flow is injected into the nozzle downstream of the throat, all of the remaining unburned fuel in the plume spontaneously ignites. This secondary reaction produces additional high pressure gases that are captured by the nozzle and significantly increases the motor's performance. Secondary injection and combustion allows a high expansion ratio (area of the nozzle exit divided by area of the throat) to be effective at low altitudes where there would normally be significantly flow separation and possibly an embedded shock wave due. The result is a 15 percent increase in produced thrust level with no loss in engine efficiency due to secondary injection. Core flow efficiency was increased significantly. Control tests performed using cylindrical fuel ports with secondary injection, and helical fuel ports without secondary injection did not exhibit this performance increase. Clearly, both the fuel-rich plume and secondary injection are essential features allowing the hybrid thrust augmentation to occur. Techniques for better design optimization are discussed.

Meteorology Meets Engineering: An Interdisciplinary STEM Module for Middle and Early Secondary School Students

ERIC Educational Resources Information Center

Barrett, Bradford S.; Moran, Angela L.; Woods, John E.

2014-01-01

Background: Given the continued need to educate the public on both the meteorological and engineering hazards posed by the severe winds of a tornado, an interdisciplinary science, technology, engineering, and mathematics (STEM) module designed by the faculty from the Oceanography and Mechanical Engineering Departments at the United States Naval…

Black Engineering Students' Motivation for PhD Attainment: Passion Plus Purpose

ERIC Educational Resources Information Center

McGee, Ebony O.; White, Devin T.; Jenkins, Akailah T.; Houston, Stacey; Bentley, Lydia C.; Smith, William J.; Robinson, William H.

2016-01-01

Purpose: Much of the extant research, practice and policy in engineering education has focused on the limited persistence, waning interest and lack of preparation among Black students to continue beyond the post-secondary engineering pipeline. However, this research suggests that many Black PhD students persist and succeed in engineering, fueled…

Dual Tank Fuel System

DOEpatents

Wagner, Richard William; Burkhard, James Frank; Dauer, Kenneth John

1999-11-16

A dual tank fuel system has primary and secondary fuel tanks, with the primary tank including a filler pipe to receive fuel and a discharge line to deliver fuel to an engine, and with a balance pipe interconnecting the primary tank and the secondary tank. The balance pipe opens close to the bottom of each tank to direct fuel from the primary tank to the secondary tank as the primary tank is filled, and to direct fuel from the secondary tank to the primary tank as fuel is discharged from the primary tank through the discharge line. A vent line has branches connected to each tank to direct fuel vapor from the tanks as the tanks are filled, and to admit air to the tanks as fuel is delivered to the engine.

ENGINEERING STUDY FOR THE 200 AREA EFFLUENT TREATMENT FACILITY (ETF) SECONDARY WASTE TREATMENT OF PROJECTED FUTURE WASTE FEEDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

LUECK, K.J.

2004-10-18

This report documents an engineering study conducted to evaluate alternatives for treating secondary waste in the secondary treatment train (STT) of the Hanford Site 200 Area Effluent Treatment Facility (ETF). The study evaluates ETF STT treatment alternatives and recommends preferred alternatives for meeting the projected future missions of the ETF. The preferred alternative(s) will process projected future ETF influents to produce a solid waste acceptable for final disposal on the Hanford Site. The main text of this report summarizes the ETF past and projected operations, lists the assumptions about projected operations that provide the basis for the engineering evaluation, andmore » summarizes the evaluation process. The evaluation process includes identification of available modifications to the current ETF process, screens those modifications for technical viability, evaluates the technically viable alternatives, and provides conclusions and recommendations based on that evaluation.« less

Metabolomics for secondary metabolite research.

PubMed

Breitling, Rainer; Ceniceros, Ana; Jankevics, Andris; Takano, Eriko

2013-11-11

Metabolomics, the global characterization of metabolite profiles, is becoming an increasingly powerful tool for research on secondary metabolite discovery and production. In this review we discuss examples of recent technological advances and biological applications of metabolomics in the search for chemical novelty and the engineered production of bioactive secondary metabolites.

Operation and Performance Measurement on Engines in Sea Level Test Facilities

DTIC Science & Technology

1984-03-01

progressively larger collector to ’:7.. *: capture the efflux, but secondary airflow increases rapidly as collector area .-- increases. Therefore...1 + Dbm + Dc + Dts + Dbt - WeVe + (Pe - P 2 )Ae where the terms above and to follow are defined as Fa - measured thrust from load cell Pn - net thrust...Dbt - buoyancy (boat-tail) drag on exhaust nozzle. Considering that . (Pe-P" 2 )Ae + WeVe - (Pe-P..)Ae + (P-1-P- 2 )Ae + WeVe and .. .* Pg (Pe-PŖ)Ae

Design Steps for Physic STEM Education Learning in Secondary School

NASA Astrophysics Data System (ADS)

Teevasuthonsakul, C.; Yuvanatheeme, V.; Sriput, V.; Suwandecha, S.

2017-09-01

This study aimed to develop the process of STEM Education activity design used in Physics subjects in the Thai secondary schools. The researchers have conducted the study by reviewing the literature and related works, interviewing Physics experts, designing and revising the process accordingly, and experimenting the designed process in actual classrooms. This brought about the five-step process of STEM Education activity design which Physics teachers applied to their actual teaching context. The results from the after-class evaluation revealed that the students’ satisfaction level toward Physics subject and critical thinking skill was found higher statistically significant at p < .05. Moreover, teachers were advised to integrate the principles of science, mathematics, technology, and engineering design process as the foundation when creating case study of problems and solutions.

Examination of factors predicting secondary students' interest in tertiary STEM education

NASA Astrophysics Data System (ADS)

Chachashvili-Bolotin, Svetlana; Milner-Bolotin, Marina; Lissitsa, Sabina

2016-02-01

Based on the Social Cognitive Career Theory (SCCT), the study aims to investigate factors that predict students' interest in pursuing science, technology, engineering, and mathematics (STEM) fields in tertiary education both in general and in relation to their gender and socio-economic background. The results of the analysis of survey responses of 2458 secondary public school students in the fifth-largest Israeli city indicate that STEM learning experience positively associates with students' interest in pursuing STEM fields in tertiary education as opposed to non-STEM fields. Moreover, studying advanced science courses at the secondary school level decreases (but does not eliminate) the gender gap and eliminates the effect of family background on students' interest in pursuing STEM fields in the future. Findings regarding outcome expectations and self-efficacy beliefs only partially support the SCCT model. Outcome expectations and self-efficacy beliefs positively correlate with students' entering tertiary education but did not differentiate between their interests in the fields of study.

Strengthening programs in science, engineering and mathematics. Third annual progress report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sandhu, S.S.

1997-09-30

The Division of Natural Sciences and Mathematics at Claflin College consists of the Departments of Biology, Chemistry, Computer Science, Physics, Engineering and Mathematics. It offers a variety of major and minor academic programs designed to meet the mission and objectives of the college. The division`s pursuit to achieve excellence in science education is adversely impacted by the poor academic preparation of entering students and the lack of equipment, facilities and research participation, required to impart adequate academic training and laboratory skills to the students. Funds were received from the US Department of Energy to improve the divisional facilities and laboratorymore » equipment and establish mechanism at pre-college and college levels to increase (1) the pool of high school students who will enroll in Science and Mathematics courses (2) the pool of well qualified college freshmen who will seek careers in Science, Engineering and Mathematics (3) the graduation rate in Science,engineering and Mathematics at the undergraduate level and (4) the pool of well-qualified students who can successfully compete to enter the graduate schools of their choice in the fields of science, engineering, and mathematics. The strategies that were used to achieve the mentioned objectives include: (1) Improved Mentoring and Advisement, (2) Summer Science Camp for 7th and 8th graders, (3) Summer Research Internships for Claflin SEM Seniors, (4) Summer Internships for Rising High School Seniors, (5) Development of Mathematical Skills at Pre-college/Post-secondary Levels, (6) Expansion of Undergraduate Seminars, (7) Exposure of Undergraduates to Guest Speakers/Roll Models, (8) Visitations by Undergraduate Students to Graduate Schools, and (9) Expanded Academic Program in Environmental Chemistry.« less

Increasing Opportunities and Success in Science, Math, Engineering and Technology Through Partnerships and Resource Convergence

NASA Astrophysics Data System (ADS)

Huebner, P.

2003-12-01

Bridging the geographic boundaries and providing educational opportunities is the goal of American Indian Programs at Arizona State University East. Since its inception in 1997, American Indian Programs has established programs and partnerships to provide opportunities and resources to Tribal communities throughout Arizona. From educational programs to enhance student achievement at the K-12 level to recruitment and retention of American Indian students at the post secondary level, American Indian Programs provides the resources to further the success of students in science, math, engineering and technology. Resource convergence is critical in providing opportunities to ensure the success of Indian students in science, math, engineering and technology. American Indian Programs has built successful programs based on partnerships between federal grant programs, corporate, federal and state agencies. Providing professional development for teachers, school assessment, science and math curriculum and data collection are the primary efforts at the K-12 level to increase student achievement. Enrichment programs to enhance K-12 activities include the development of the Arizona American Indian Science and Engineering Fair (the only State fair for American Indiana's in the country) supported entirely through corporate support, summer residential programs, after school activities and dual enrollment programs for high school students. ASU East's retention rate for first year students is 92 percent and 1in 6 graduating students enter graduate programs. American Indian Programs strives to build student relationships with federal, state and corporate agencies through internships and coops. This effort has led to the development of an E-mentoring program that allows students (and K-12 teachers) to work directly with practicing scientists, and engineers in research activities. New programs look to increase technology not only in Tribal schools but increase technology in the homes of students as well.

Metabolic engineering of Escherichia coli: a sustainable industrial platform for bio-based chemical production.

PubMed

Chen, Xianzhong; Zhou, Li; Tian, Kangming; Kumar, Ashwani; Singh, Suren; Prior, Bernard A; Wang, Zhengxiang

2013-12-01

In order to decrease carbon emissions and negative environmental impacts of various pollutants, more bulk and/or fine chemicals are produced by bioprocesses, replacing the traditional energy and fossil based intensive route. The Gram-negative rod-shaped bacterium, Escherichia coli has been studied extensively on a fundamental and applied level and has become a predominant host microorganism for industrial applications. Furthermore, metabolic engineering of E. coli for the enhanced biochemical production has been significantly promoted by the integrated use of recent developments in systems biology, synthetic biology and evolutionary engineering. In this review, we focus on recent efforts devoted to the use of genetically engineered E. coli as a sustainable platform for the production of industrially important biochemicals such as biofuels, organic acids, amino acids, sugar alcohols and biopolymers. In addition, representative secondary metabolites produced by E. coli will be systematically discussed and the successful strategies for strain improvements will be highlighted. Moreover, this review presents guidelines for future developments in the bio-based chemical production using E. coli as an industrial platform. Copyright © 2013 Elsevier Inc. All rights reserved.

Project-Based Learning and Design-Focused Projects to Motivate Secondary Mathematics Students

ERIC Educational Resources Information Center

Remijan, Kelly W.

2017-01-01

This article illustrates how mathematics teachers can develop design-focused projects, related to project-based learning, to motivate secondary mathematics students. With first-hand experience as a secondary mathematics teacher, I provide a series of steps related to the engineering design process, which are helpful to teachers in developing…

Samarium Cobalt (SmCo) Generator/Engine Integration Study

DTIC Science & Technology

1980-04-01

110o1110 (Cole Ms -W~ Daiwa. to* J11 tuo.in Wfi wee -004"ni Aircraft Generator/starter Samarium Cobalt Turbine Engine , Feasibility Secondary Power...integration into the main rotor system of typical aircraft gas turbine engines . A major objective is the definition of the engine interface for such... Engine The F404 is a low bypass, augmented turbofan Pngine developed for application in advanced fighter aircraft (F-18). This type of engine benefits most

Academic Instruction with the Visible V-8 Engine. The Coordinated Correlated Instructional Program.

ERIC Educational Resources Information Center

Davis, W. J.

The book presents three 93-day lesson plans to motivate and teach handicapped secondary students basic academic skills in reading and language arts, English, and mathematics in conjunction with learning about automobile engines from Revell's Visible V8 Engine Kit. Each lesson plan is correlated with the Visible V8 Engine Kit and includes daily…

40 CFR 1039.625 - What requirements apply under the program for equipment-manufacturer flexibility?

Code of Federal Regulations, 2011 CFR

2011-07-01

... is manufactured. (4) An e-mail address and phone number to contact for further information, or a Web... secondary engine manufacturers. (l) [Reserved] (m) Additional exemptions for technical or engineering... avoided with reasonable discretion have resulted in technical or engineering problems that prevent you...

Growth of Engineering Education in India: Status, Issues, and Challenges

ERIC Educational Resources Information Center

Choudhury, Pradeep Kumar

2016-01-01

This article examines the growth of engineering education in India in the post-economic reform period using the secondary data published by Ministry of Human Resource Development, University Grants Commission and All India Council for Technical Education. Particularly, this article has focused on three important dimensions of engineering and…

Steady-state and dynamic analysis of a jet engine, gas lubricated shaft seal

NASA Technical Reports Server (NTRS)

Shapiro, W.; Colsher, R.

1974-01-01

Dynamic response of a gas-lubricated, jet-engine main shaft seal was analytically established as a function of collar misalignment and secondary seal friction. Response was obtained by a forward integration-in-time (time-transient) scheme, which traces a time history of seal motions in all its degrees of freedom. Results were summarized in the form of a seal tracking map which indicated regions of acceptable collar misalignments and secondary seal friction. Methodology, results and interpretations are comprehensively described.

Development of Accelerated Fuel-Engines Qualification Procedures Methodology. Volume II. Appendices.

DTIC Science & Technology

1981-12-01

temperature test and the spot calibration, remove the clay filter. Reset the maximum fuel temperature safety device for 1900F. Continue cycling per Figure...34 -t " ;" " pum p . 1...0.,. Fuel ’ ’ ’ :’: ? Secondary ; Filter (S) -, A TVented Cap Removable Screen\\ - Tank Fu e.l ExpansSon DtVrent Pipe A n...practice, improper installation or adjustment of components *Do not remove or inspect secondary fuel filter. One of the initial production engines is

Secondary air injection system and method

DOEpatents

Wu, Ko-Jen; Walter, Darrell J.

2014-08-19

According to one embodiment of the invention, a secondary air injection system includes a first conduit in fluid communication with at least one first exhaust passage of the internal combustion engine and a second conduit in fluid communication with at least one second exhaust passage of the internal combustion engine, wherein the at least one first and second exhaust passages are in fluid communication with a turbocharger. The system also includes an air supply in fluid communication with the first and second conduits and a flow control device that controls fluid communication between the air supply and the first conduit and the second conduit and thereby controls fluid communication to the first and second exhaust passages of the internal combustion engine.

1999 NASA Seal/Secondary Air System Workshop

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Hendricks, Robert C.

2000-01-01

NASA Glenn hosted the Seals/Secondary Air System Workshop on October 2829, 1999. Each year NASA and our industry and university partners share their respective seal technology development. We use these workshops as a technical forum to exchange recent advancements and "lessons-learned" in advancing seal technology and solving problems of common interest. As in the past we are publishing two volumes. Volume 1 will be publicly available and will be made available on-line through the web page address listed at the end of this chapter. Volume 2 will be restricted under International Traffic and Arms Regulations (I.T.A.R.) In this conference participants gained an appreciation of NASA's new Ultra Efficient Engine Technology (UEET) program and how this program will be partnering with ongoing DOE -industrial power production and DOD- military aircraft engine programs. In addition to gaining a deeper understanding into sealing advancements and challenges that lie ahead, participants gained new working and personal relationships with the attendees. When the seals and secondary fluid management program was initiated, the emphasis was on rocket engines with spinoffs to gas turbines. Today, the opposite is true and we are, again building our involvement in the rocket engine and space vehicle demonstration programs.

Engineering Professional Development Design for Secondary School Teachers: A Multiple Case Study

ERIC Educational Resources Information Center

Daugherty, Jenny Lynn

2009-01-01

The complexity of engineering and its integration into K-12 education have resulted in a variety of issues requiring sustained empirical research (Johnson, Burghardt, & Daugherty, 2008). One particular area of need, given the emphasis on teacher effects on student learning, is to research engineering-oriented teacher professional development. A…

Science and Technology Resources on the Internet: Standards Resources for Engineering and Technology

ERIC Educational Resources Information Center

Phillips, Margaret; Huber, Sarah

2017-01-01

The goal of this webliography is to provide an introduction to standards resources for librarians that support post-secondary engineering and technology programs, as well as engineering and technology faculty members and students. It serves as a reference on standards collection development and integrating standards information literacy into…

Curriculum Outline for Introduction to Engineering Chemistry. First Edition. Review Cycle-Annual.

ERIC Educational Resources Information Center

Schlenker, Richard M.

This curriculum outline consists of behavioral objectives (called terminal and enabling objectives) for Introduction to Engineering Chemistry, a one-semester, post-secondary course consisting of four 1-hour lectures each week. Course goal is to introduce marine engineering students to the rudiments of basic/introductory inorganic chemistry. The…

Developing Tomorrows Engineers: A Case Study in Instrument Engineering

ERIC Educational Resources Information Center

McDonnell, Liam; O'Neill, Donal

2009-01-01

Purpose: The purpose of this case study is to outline the challenges facing industry and educational institutions in educating and training instrument engineers against a backdrop of declining interest by secondary school students in mathematics and physics. This case study cites the experience and strategies of the Kentz Group and Cork Institute…

Inclusion by Design: Engineering Inclusive Practices in Secondary Schools

ERIC Educational Resources Information Center

Dukes, Charles; Lamar-Dukes, Pamela

2009-01-01

In order to help teachers understand the importance of intentional design for inclusive education, this article describes the design process an engineer might use when designing a new project. If teachers learn to think like engineers, it is possible for them to design inclusive education. This conceptual design can then be combined with…

Teacher Challenges to Implement Engineering Design in Secondary Technology Education

ERIC Educational Resources Information Center

Kelley, Todd R.; Wicklein, Robert C.

2009-01-01

This descriptive study examined the current status of technology education teacher practices with respect to engineering design. This article is the third article in a three-part series presenting the results of this study. The first article in the series titled "Examination of Engineering Design Curriculum Content" highlighted the research…

Evaluation of a 40 to 1 scale model of a low pressure engine

NASA Technical Reports Server (NTRS)

Cooper, C. E., Jr.; Thoenes, J.

1972-01-01

An evaluation of a scale model of a low pressure rocket engine which is used for secondary injection studies was conducted. Specific objectives of the evaluation were to: (1) assess the test conditions required for full scale simulations; (2) recommend fluids to be used for both primary and secondary flows; and (3) recommend possible modifications to be made to the scale model and its test facility to achieve the highest possible degree of simulation. A discussion of the theoretical and empirical scaling laws which must be observed to apply scale model test data to full scale systems is included. A technique by which the side forces due to secondary injection can be analytically estimated is presented.

Application of computational fluid dynamics to the design of the Space Transportation Main Engine subscale nozzle

NASA Technical Reports Server (NTRS)

Garrett, J. L.; Syed, S. A.

1992-01-01

CFD analyses of the Space Transportation Main Engine film/dump cooled subscale nozzle are presented, with an emphasis on the timely impact of CFD in the design of the subscale nozzle secondary coolant system. Calculations were performed with the Generalized Aerodynamic Simulation Program (GASP), using a Baldwin-Lomas Turbulence model, and finite rate hydrogen-oxygen chemistry. Design iterations for both the secondary coolant cavity passage and the secondary coolant lip are presented. In addition, validation of the GASP chemistry and turbulence models by comparison with data and other CFD codes are presented for a hypersonic laminar separation corner, a backward facing step, and a 2D scramjet nozzle with hydrogen-oxygen kinetics.

PBF (PER620) interior. System control racks, secondary control and equipment ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PBF (PER-620) interior. System control racks, secondary control and equipment room. Date: May 2004. INEEL negative no. HD-41-6-2 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

How Things Work: The Physics of Everyday Life, 2nd Edition

NASA Astrophysics Data System (ADS)

Bloomfield, Louis A.

2000-12-01

Written primarily for a one-term, undergraduate level course, this book attempts to convey an understanding and appreciation for the concepts and principles of Physics by finding them within specific objects of everyday experience. It's primary market are liberal arts students who are seeking a connection between science and the world they live in; among its many secondary markets are the growing number of institutions offering courses with scientific real-world context. These courses may also be offered to students from the Sciences, Engineering, Architecture, and other technical fields.

49 CFR 523.2 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., shoulder room, and leg room dimensions determined in accordance with the procedures outlined in Society of... Engineering Committee, Society of Automotive Engineers, approved September 1973 and last revised September... secondary vehicle manufacturers. Incomplete vehicles include cab-complete vehicles. Innovative technology...

Afterburning control of internal combustion engine exhaust gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakajima, Y.; Hayashi, Y.; Nagumo, S.I.

1976-08-17

Flow of secondary air into the exhaust system is regulated by diaphragm assembly controlled valves between an air supply and the exhaust system. The diaphragm assemblies respond to vacuum in the intake air system of the engine.

A mathematical model for jet engine combustor pollutant emissions

NASA Technical Reports Server (NTRS)

Boccio, J. L.; Weilerstein, G.; Edelman, R. B.

1973-01-01

Mathematical modeling for the description of the origin and disposition of combustion-generated pollutants in gas turbines is presented. A unified model in modular form is proposed which includes kinetics, recirculation, turbulent mixing, multiphase flow effects, swirl and secondary air injection. Subelements of the overall model were applied to data relevant to laboratory reactors and practical combustor configurations. Comparisons between the theory and available data show excellent agreement for basic CO/H2/Air chemical systems. For hydrocarbons the trends are predicted well including higher-than-equilibrium NO levels within the fuel rich regime. Although the need for improved accuracy in fuel rich combustion is indicated, comparisons with actual jet engine data in terms of the effect of combustor-inlet temperature is excellent. In addition, excellent agreement with data is obtained regarding reduced NO emissions with water droplet and steam injection.

A Basic Engineering English Word List for Less Proficient Foundation Engineering Undergraduates

ERIC Educational Resources Information Center

Ward, Jeremy

2009-01-01

This paper concerns the teaching of English to learners who are studying, or will soon study, engineering and who are expected to do at least part of their studying through textbooks written in English. Such students, especially in universities in developing countries, often find themselves very poorly equipped by their secondary education for…

Mississippi Curriculum Framework for Small Engine Repair (Program CIP: 47.0606--Small Engine Mechanic and Repairer). Secondary Programs.

ERIC Educational Resources Information Center

Mississippi Research and Curriculum Unit for Vocational and Technical Education, State College.

This document, which reflects Mississippi's statutory requirement that instructional programs be based on core curricula and performance-based assessment, contains outlines of the instructional units required in local instructional management plans and daily lesson plans for small engine repair I and II. Presented first are a program description…

Examination of Assessment Practices for Engineering Design Projects in Secondary Technology Education (Second Article in 3-Part Series)

ERIC Educational Resources Information Center

Kelley, Todd R.; Wicklein, Robert C.

2009-01-01

Based on the efforts to infuse engineering practices within the technology education curriculum it is appropriate to now investigate how technology education teachers are assessing engineering design activities within their classrooms. This descriptive study drew a full sample of high school technology teachers from the current International…

Integrating Engineering Design Challenges into Secondary STEM Education

ERIC Educational Resources Information Center

Carr, Ronald L.; Strobel, Johannes

2011-01-01

Engineering is being currently taught in the full spectrum of the P-12 system, with an emphasis on design-oriented teaching (Brophy, Klein, Portsmore, & Rogers, 2008). Due to only a small amount of research on the learning of engineering design in elementary and middle school settings, the community of practice lacks the necessary knowledge of the…

Advanced Gas Turbine (AGT) Technology Project

NASA Technical Reports Server (NTRS)

1984-01-01

Technical work on the design and effort leading to the testing of a 74.5 kW (100 hp) automotive gas turbine engine is reviewed. Development of the engine compressor, gasifier turbine, power turbine, combustor, regenerator, and secondary system is discussed. Ceramic materials development and the application of such materials in the gas turbine engine components is described.

Enhanced air/fuel mixing for automotive stirling engine turbulator-type combustors

DOEpatents

Riecke, George T.; Stotts, Robert E.

1992-01-01

The invention relates to the improved combustion of fuel in a combustion chamber of a stirling engine and the like by dividing combustion into primary and secondary combustion zones through the use of a diverter plate.

Cumulative metal leaching from utilisation of secondary building materials in river engineering.

PubMed

Leuven, R S E W; Willems, F H G

2004-01-01

The present paper estimates the utilisation of bulky wastes (minestone, steel slag, phosphorus slag and demolition waste) in hydraulic engineering structures in Dutch parts of the rivers Rhine, Meuse and Scheldt over the period 1980-2025. Although they offer several economic, technical and environmental benefits, these secondary building materials contain various metals that may leach into river water. A leaching model was used to predict annual emissions of arsenic, cadmium, copper, chromium, lead, mercury, nickel and zinc. Under the current utilisation and model assumptions, the contribution of secondary building materials to metal pollution in Dutch surface waters is expected to be relatively low compared to other sources (less than 0.1% and 0.2% in the years 2000 and 2025, respectively). However, continued and widespread large-scale applications of secondary building materials will increase pollutant leaching and may require further cuts to be made in emissions from other sources to meet emission reduction targets and water quality standards. It is recommended to validate available leaching models under various field conditions. Complete registration of secondary building materials will be required to improve input data for leaching models.

Our school's Earth and Space Sciences Club: 12 years promoting interdisciplinary explorations

NASA Astrophysics Data System (ADS)

Margarida Maria, Ana; Pereira, Hélder

2017-04-01

During the past 12 years, we have been engaging secondary level science students (15 to 18 years old) in the extracurricular activities of our school's Earth and Space Sciences Club, providing them with some of the skills needed to excel in science, technology, engineering, arts, and mathematics (STEAM). Our approach includes the use of authentic scientific data, project based learning, and inquiry-centred activities that go beyond the models and theories present in secondary level textbooks. Moreover, the activities and projects carried out, being eminently practical, also function as an extension of the curriculum and frequently enable the demonstration of the applicability of several concepts taught in the classroom in real life situations. The tasks carried out during these activities and research projects often require the combination of two or more subjects, promoting an interdisciplinary approach to learning. Outside of the traditional classroom settings, through interdisciplinary explorations, students also gain hands-on experience doing real science. Thereby, during this time, we have been able to promote meaningful and lasting experiences and spark students' interest in a wide diversity of topics.

Combustion characteristics of hydrogen. Carbon monoxide based gaseous fuels

NASA Technical Reports Server (NTRS)

Notardonato, J. J.; White, D. J.; Kubasco, A. J.; Lecren, R. T.

1981-01-01

An experimental rig program was conducted with the objective of evaluating the combuston performance of a family of fuel gases based on a mixture of hydrogen and carbon monoxide. These gases, in addition to being members of a family, were also representative of those secondary fuels that could be produced from coal by various gasification schemes. In particular, simulated Winkler, Lurgi, and Blue-water low and medium energy content gases were used as fuels in the experimental combustor rig. The combustor used was originally designed as a low NOx rich-lean system for burning liquid fuels with high bound nitrogen levels. When used with the above gaseous fuels this combustor was operated in a lean-lean mode with ultra long residence times. The Blue-water gas was also operated in a rich-lean mode. The results of these tests indicate the possibility of the existence of an 'optimum' gas turbine hydrogen - carbon monoxide based secondary fuel. Such a fuel would exhibit NOx and high efficiency over the entire engine operating range. It would also have sufficient stability range to allow normal light-off and engine acceleration. Solar Turbines Incorporated would like to emphasize that the results presented here have been obtained with experimental rig combustors. The technologies generated could, however, be utilized in future commercial gas turbines.

Pathways to excellence: A Federal strategy for science, mathematics, engineering, and technology education

NASA Astrophysics Data System (ADS)

This Strategic Plan was developed by the Federal Coordinating Council for Science, Engineering, and Technology (FCCSET) through its Committee on Education and Human Resources (CEHR), with representatives from 16 Federal agencies. Based on two years of coordinated interagency effort, the Plan confirms the Federal Government's commitment to ensuring the health and well-being of science, mathematics, engineering, and technology education at all levels and in all sectors (i.e., elementary and secondary, undergraduate, graduate, public understanding of science, and technology education). The Plan represents the Federal Government's efforts to develop a five-year planning framework and associated milestones that focus Federal planning and the resources of the participating agencies toward achieving the requisite or expected level of mathematics and science competence by all students. The priority framework outlines the strategic objectives, implementation priorities, and components for the Strategic Plan and serves as a road map for the Plan. The Plan endorses a broad range of ongoing activities, including continued Federal support for graduate education as the backbone of our country's research and development enterprise. The Plan also identifies three tiers of program activities with goals that address issues in science, mathematics, engineering, and technology education meriting special attention. Within each tier, individual agency programs play important and often unique roles that strengthen the aggregate portfolio. The three tiers are presented in descending order of priority: (1) reforming the formal education system; (2) expanding participation and access; and (3) enabling activities.

Chemical characterisation of dredged sediments in relation to their potential use in civil engineering.

PubMed

Zuliani, Tea; Mladenovič, Ana; Ščančar, Janez; Milačič, Radmila

2016-04-01

During capital and/or maintenance dredging operations, large amounts of material are produced. Instead of their discharge, dredged sediments may be a valuable natural resource if not contaminated. One of the possible areas of application is civil engineering. In the present work, the environmental status of seaport dredged sediment was evaluated in order to investigate its potential applicability as a secondary raw material. Sediments were analysed for element concentrations in digested samples, aqueous extracts and fractions from sequential extraction; for fluoride, chloride and sulphate concentrations in aqueous extracts; and for tributyltin (TBT). Granulometric and mineralogical compositions were also analysed. The elemental impact was evaluated by calculation of the enrichment factors. The total element concentrations determined showed moderate contamination of the dredged sediments as was confirmed also by their moderate enrichment factors, presumably as a result of industrial and port activities. Elemental concentrations in the aqueous extract were very low and therefore do not represent any hazard for the environment. The water-soluble element concentrations were under the threshold levels set by the EU Directive on the landfill of waste, on the basis of which the applicability of dredged sediments in civil engineering is evaluated, while the content of chloride and sulphate were above the threshold levels. It was found out that due to the large amounts of sediment available, civil engineering applications such as the construction of embankments and backfilling is the most beneficial recycling solution at present.

Pathways to excellence: A Federal strategy for science, mathematics, engineering, and technology education

NASA Technical Reports Server (NTRS)

1993-01-01

This Strategic Plan was developed by the Federal Coordinating Council for Science, Engineering, and Technology (FCCSET) through its Committee on Education and Human Resources (CEHR), with representatives from 16 Federal agencies. Based on two years of coordinated interagency effort, the Plan confirms the Federal Government's commitment to ensuring the health and well-being of science, mathematics, engineering, and technology education at all levels and in all sectors (i.e., elementary and secondary, undergraduate, graduate, public understanding of science, and technology education). The Plan represents the Federal Government's efforts to develop a five-year planning framework and associated milestones that focus Federal planning and the resources of the participating agencies toward achieving the requisite or expected level of mathematics and science competence by all students. The priority framework outlines the strategic objectives, implementation priorities, and components for the Strategic Plan and serves as a road map for the Plan. The Plan endorses a broad range of ongoing activities, including continued Federal support for graduate education as the backbone of our country's research and development enterprise. The Plan also identifies three tiers of program activities with goals that address issues in science, mathematics, engineering, and technology education meriting special attention. Within each tier, individual agency programs play important and often unique roles that strengthen the aggregate portfolio. The three tiers are presented in descending order of priority: (1) reforming the formal education system; (2) expanding participation and access; and (3) enabling activities.

Engineering Technologies. State Competency Profile.

ERIC Educational Resources Information Center

Ohio State Univ., Columbus. Center on Education and Training for Employment.

This document contains 397 competencies, grouped into 58 units, for tech prep programs in the engineering technologies cluster. The competencies were developed through collaboration of Ohio business, industry, and labor representatives and secondary and associate degree educators. The competencies are rated either "essential" (necessary…

Changing Priorities

ERIC Educational Resources Information Center

Wimberly, Charles A.; Wynne, Lewis N.

1974-01-01

The future of many post-secondary institutions may rest with their ability to shift from a strict engineering format to one incorporating community service programs. Retraining competent unemployed technicians and engineers from aerospace and military sectors for construction, community service, and environmental protection can be an important…

Prediction of 10-year coronary heart disease risk in Caribbean type 2 diabetic patients using the UKPDS risk engine.

PubMed

Ezenwaka, C E; Nwagbara, E; Seales, D; Okali, F; Hussaini, S; Raja, Bn; Jones-LeCointe, A; Sell, H; Avci, H; Eckel, J

2009-03-06

Primary prevention of Coronary Heart Disease (CHD) in diabetic patients should be based on absolute CHD risk calculation. This study was aimed to determine the levels of 10-year CHD risk in Caribbean type 2 diabetic patients using the diabetes specific United Kingdom Prospective Diabetes Study (UKPDS) risk engine calculator. Three hundred and twenty-five (106 males, 219 females) type 2 diabetic patients resident in two Caribbean Islands of Tobago and Trinidad met the UKPDS risk engine inclusion criteria. Records of their sex, age, ethnicity, smoking habit, diabetes duration, systolic blood pressure, total cholesterol, HDL-cholesterol and glycated haemoglobin were entered into the UKPDS risk engine calculator programme and the absolute 10-year CHD and stroke risk levels were computed. The 10-year CHD and stroke risks were statistically stratified into <15%, 15-30% and >30% CHD risk levels and differences between patients of African and Asian-Indian origin were compared. In comparison with patients in Tobago, type 2 diabetic patients in Trinidad, irrespective of gender, had higher proportion of 10-year CHD risk (10.4 vs. 23.6%, P<0.001) whereas the overall 10-year stroke risk prediction was higher in patients resident in Tobago (16.9 vs. 11.4%, P<0.001). Ethnicity-based analysis revealed that irrespective of gender, higher proportion of patients of Indian origin scored >30% of absolute 10-year CHD risk compared with patients of African descent (3.2 vs. 28.2%, P<0.001). The results of the study identified diabetic patients resident in Trinidad and patients of Indian origin as the most vulnerable groups for CHD. These groups of diabetic patients should have priority in primary or secondary prevention of coronary heart disease.

Genetic Engineering: A Matter that Requires Further Refinement in Spanish Secondary School Textbooks

ERIC Educational Resources Information Center

Martinez-Gracia, M. V.; Gil-Quylez, M. J.; Osada, J.

2003-01-01

Genetic engineering is now an integral part of many high school textbooks but little work has been done to assess whether it is being properly addressed. A checklist with 19 items was used to analyze how genetic engineering is presented in biology textbooks commonly used in Spanish high schools, including the content, its relationship with…

Relative performance comparison between baseline labyrinth and dual-brush compressor discharge seals in a T-700 engine test

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.; Griffin, Thomas A.; Kline, Teresa R.; Csavina, Kristine R.; Pancholi, Arvind; Sood, Devendra

1995-01-01

In separate series of YT-700 engine tests, direct comparisons were made between the forward-facing labyrinth and dual brush compressor discharge seals. Compressor speeds to 43 000 rpm, surface speeds to 160 m/s (530 ft/s), pressures to 1 MPa (145 psi), and temperatures to 680 K (765 F) characterized these tests. The wear estimate for 46 hr of engine operations was less than 0.025 mm (0.001 in.) of the Haynes 25 alloy bristles running against a chromium-carbide-coated rub runner. The pressure drops were higher for the dual-brush seal than for the forward-facing labyrinth seal and leakage was lower-with the labyrinth seal leakage being 2-1/2 times greater-implying better seal characteristics, better secondary airflow distribution, and better engine performance (3 percent at high pressure to 5 percent at lower pressure) for the brush seal. (However, as brush seals wear down (after 500 to 1000 hr of engine operation), their leakage rates will increase.) Modification of the secondary flow path requires that changes in cooling air and engine dynamics be accounted for.

Metabolic engineering of Klebsiella pneumoniae for the de novo production of 2-butanol as a potential biofuel.

PubMed

Chen, Zhen; Wu, Yao; Huang, Jinhai; Liu, Dehua

2015-12-01

Butanol isomers are important bulk chemicals and promising fuel substitutes. The inevitable toxicity of n-butanol and isobutanol to microbial cells hinders their final titers. In this study, we attempt to engineer Klebsiella pneumoniae for the de novo production of 2-butanol, another butanol isomer which shows lower toxicity than n-butanol and isobutanol. 2-Butanol synthesis was realized by the extension of the native meso-2,3-butanediol synthesis pathway with the introduction of diol dehydratase and secondary alcohol dehydrogenase. By the screening of different secondary alcohol dehydrogenases and diol dehydratases, 320mg/L of 2-butanol was produced by the best engineered K. pneumoniae. The production was increased to 720mg/L by knocking out the ldhA gene and appropriate addition of coenzyme B12. Further improvement of 2-butanol to 1030mg/L was achieved by protein engineering of diol dehydratase. This work lays the basis for the metabolic engineering of microorganism for the production of 2-butanol as potential biofuel. Copyright © 2015 Elsevier Ltd. All rights reserved.

Engineering Pseudomonas for phenazine biosynthesis, regulation, and biotechnological applications: a review.

PubMed

Bilal, Muhammad; Guo, Shuqi; Iqbal, Hafiz M N; Hu, Hongbo; Wang, Wei; Zhang, Xuehong

2017-10-03

Pseudomonas strains are increasingly attracting considerable attention as a valuable bacterial host both for basic and applied research. It has been considered as a promising candidate to produce a variety of bioactive secondary metabolites, particularly phenazines. Apart from the biotechnological perspective, these aromatic compounds have the notable potential to inhibit plant-pathogenic fungi and thus are useful in controlling plant diseases. Nevertheless, phenazines production is quite low by the wild-type strains that necessitated its yield improvement for large-scale agricultural applications. Metabolic engineering approaches with the advent of plentiful information provided by systems-level genomic and transcriptomic analyses enabled the development of new biological agents functioning as potential cell factories for producing the desired level of value-added bioproducts. This study presents an up-to-date overview of recombinant Pseudomonas strains as the preferred choice of host organisms for the biosynthesis of natural phenazines. The biosynthetic pathway and regulatory mechanism involved in the phenazine biosynthesis are comprehensively discussed. Finally, a summary of biological functionalities and biotechnological applications of the phenazines is also provided.

Modeling reacting gases and aftertreatment devices for internal combustion engines

NASA Astrophysics Data System (ADS)

Depcik, Christopher David

As more emphasis is placed worldwide on reducing greenhouse gas emissions, automobile manufacturers have to create more efficient engines. Simultaneously, legislative agencies want these engines to produce fewer problematic emissions such as nitrogen oxides and particulate matter. In response, newer combustion methods, like homogeneous charge compression ignition and fuel cells, are being researched alongside the old standard of efficiency, the compression ignition or diesel engine. These newer technologies present a number of benefits but still have significant challenges to overcome. As a result, renewed interest has risen in making diesel engines cleaner. The key to cleaning up the diesel engine is the placement of aftertreatment devices in the exhaust. These devices have shown great potential in reducing emission levels below regulatory levels while still allowing for increased fuel economy versus a gasoline engine. However, these devices are subject to many flow control issues. While experimental evaluation of these devices helps to understand these issues better, it is impossible to solve the problem through experimentation alone because of time and cost constraints. Because of this, accurate models are needed in conjunction with the experimental work. In this dissertation, the author examines the entire exhaust system including reacting gas dynamics and aftertreatment devices, and develops a complete numerical model for it. The author begins by analyzing the current one-dimensional gas-dynamics simulation models used for internal combustion engine simulations. It appears that more accurate and faster numerical method is available, in particular, those developed in aeronautical engineering, and the author successfully implements one for the exhaust system. The author then develops a comprehensive literature search to better understand the aftertreatment devices. A number of these devices require a secondary injection of fuel or reductant in the exhaust stream. Accordingly, the author develops a simple post-cylinder injection model which can be easily tuned to match experimental findings. In addition, the author creates a general catalyst model which can be used to model virtually all of the different aftertreatment devices. Extensive validation of this model with experimental data is presented along with all of the numerical algorithms needed to reproduce the model.

From Paper to Production to Test: An Update on NASA's J-2X Engine for Exploration

NASA Technical Reports Server (NTRS)

Kynard, Michael

2011-01-01

The NASA/industry team responsible for developing the J-2X upper stage engine for the Space Launch System (SLS) Program has made significant progress toward moving beyond the design phase and into production, assembly, and test of development hardware. The J-2X engine exemplifies the SLS Program goal of using proven technology and experience from more than 50 years of United States spaceflight experience combined with modern manufacturing processes and approaches. It will power the second stage of the fully evolved SLS Program launch vehicle that will enable a return to human exploration of space beyond low earth orbit. Pratt & Whitney Rocketdyne (PWR) is under contract to develop and produce the engine, leveraging its flight-proven LH2/LOX, gas generator cycle J-2 and RS-68 engine capabilities, recent experience with the X-33 aerospike XRS-2200 engine, and development knowledge of the J-2S tap-off cycle engine. The J- 2X employs a gas generator operating cycle designed to produce 294,000 pounds of vacuum thrust in primary operating mode with its full nozzle extension. With a truncated nozzle extension suitable to support engine clustering on the stage, the nominal vacuum thrust level in primary mode is 285,000 pounds. It also has a secondary mode, during which it operates at 80 percent thrust by altering its mixture ratio. The J-2X development philosophy is based on proven hardware, an aggressive development schedule, and early risk reduction. NASA Marshall Space Flight Center (MSFC) and PWR began development of the J-2X in June 2006. The government/industry team of more than 600 people within NASA and PWR successfully completed the Critical Design Review (CDR) in November 2008, following extensive risk mitigation testing. Assembly of the first development engine was completed in May 2011 and the first engine test was conducted at the NASA Stennis Space Center (SSC), test stand A2, on 14 July 2011. Testing of the first development engine will continue through the autumn of 2011, be paused for test stand modifications to the passive diffuser, and then restart in the spring of 2012. This testing will be followed by specialized powerpack testing intended to examine the design and operating margins of the engine turbomachinery. The development plan beyond this point leads through more system-level, engine testing of several samples, analytical model validation activities, functional and performance verification, and then ultimate certification to support human spaceflight. This paper will discuss the J-2X development background, provide top-level information on design and development planning, and will explore some of the development challenges and mitigation activities pursued to date.

Transitioning to Secondary School: The Case of Mathematics

ERIC Educational Resources Information Center

Carmichael, Colin

2015-01-01

At a time when Australia's international competitiveness is compromised by a shortage of skilled workers in Science, Technology, Engineering and Mathematics (STEM) related careers, reports suggest a decline in Australian secondary school students' performances in international tests of mathematics. This study focuses on the mathematics performance…

Aircraft Electric Secondary Power

NASA Technical Reports Server (NTRS)

1983-01-01

Technologies resulted to aircraft power systems and aircraft in which all secondary power is supplied electrically are discussed. A high-voltage dc power generating system for fighter aircraft, permanent magnet motors and generators for aircraft, lightweight transformers, and the installation of electric generators on turbine engines are among the topics discussed.

Perceptions of STEM-Based Outreach Learning Activities in Secondary Education

ERIC Educational Resources Information Center

Vennix, J.; den Brok, P.; Taconis, R.

2017-01-01

We investigated and compared the learning environment perceptions of students, teachers and guides who participated in Science, Technology, Engineering and Mathematics (STEM)-based outreach activities in secondary education. In outreach activities, schools and teachers work together with companies and other external institutions in learning…

Advanced secondary power system for transport aircraft

NASA Technical Reports Server (NTRS)

Hoffman, A. C.; Hansen, I. G.; Beach, R. F.; Plencner, R. M.; Dengler, R. P.; Jefferies, K. S.; Frye, R. J.

1985-01-01

A concept for an advanced aircraft power system was identified that uses 20-kHz, 440-V, sin-wave power distribution. This system was integrated with an electrically powered flight control system and with other aircraft systems requiring secondary power. The resulting all-electric secondary power configuration reduced the empty weight of a modern 200-passenger, twin-engine transport by 10 percent and the mission fuel by 9 percent.

Thermal reactor for afterburning automotive internal combustion engine exhaust gases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masaki, K.; Nagaishi, H.

1974-08-08

A thermal reactor for burning unburned components in exhaust gases of an internal combustion engine before emission to the atmosphere is described. An outer casing has an exhaust gas inlet connected to the exhaust ports, and an inner casing divides the reactor into an outer chamber and an inner chamber. The inner casing has an inlet from the outer chamber, an outlet to the atmosphere, and perforations opening to the outer chamber. An oxidation catalyst in the inner chamber promotes oxidation of the unburned components in the exhaust gases to generate oxidation reaction heat. A first secondary air injection nozzlemore » in the inner chamber between the oxidation catalyst and the outlet and a second secondary air injection nozzle in a portion upstream of the oxidation catalyst inject secondary air into oxidation catalyst.« less

Engineering of plants with improved properties as biofuels feedstocks by vessel-specific complementation of xylan biosynthesis mutants

PubMed Central

2012-01-01

Background Cost-efficient generation of second-generation biofuels requires plant biomass that can easily be degraded into sugars and further fermented into fuels. However, lignocellulosic biomass is inherently recalcitrant toward deconstruction technologies due to the abundant lignin and cross-linked hemicelluloses. Furthermore, lignocellulosic biomass has a high content of pentoses, which are more difficult to ferment into fuels than hexoses. Engineered plants with decreased amounts of xylan in their secondary walls have the potential to render plant biomass a more desirable feedstock for biofuel production. Results Xylan is the major non-cellulosic polysaccharide in secondary cell walls, and the xylan deficient irregular xylem (irx) mutants irx7, irx8 and irx9 exhibit severe dwarf growth phenotypes. The main reason for the growth phenotype appears to be xylem vessel collapse and the resulting impaired transport of water and nutrients. We developed a xylan-engineering approach to reintroduce xylan biosynthesis specifically into the xylem vessels in the Arabidopsis irx7, irx8 and irx9 mutant backgrounds by driving the expression of the respective glycosyltransferases with the vessel-specific promoters of the VND6 and VND7 transcription factor genes. The growth phenotype, stem breaking strength, and irx morphology was recovered to varying degrees. Some of the plants even exhibited increased stem strength compared to the wild type. We obtained Arabidopsis plants with up to 23% reduction in xylose levels and 18% reduction in lignin content compared to wild-type plants, while exhibiting wild-type growth patterns and morphology, as well as normal xylem vessels. These plants showed a 42% increase in saccharification yield after hot water pretreatment. The VND7 promoter yielded a more complete complementation of the irx phenotype than the VND6 promoter. Conclusions Spatial and temporal deposition of xylan in the secondary cell wall of Arabidopsis can be manipulated by using the promoter regions of vessel-specific genes to express xylan biosynthetic genes. The expression of xylan specifically in the xylem vessels is sufficient to complement the irx phenotype of xylan deficient mutants, while maintaining low overall amounts of xylan and lignin in the cell wall. This engineering approach has the potential to yield bioenergy crop plants that are more easily deconstructed and fermented into biofuels. PMID:23181474

In Brief: Improving science education

NASA Astrophysics Data System (ADS)

Showstack, Randy

2010-09-01

Over the course of the next decade, 100,000 science, technology, engineering, and math (STEM) teachers should be recruited in the United States, and 1000 new STEM-focused schools should be created, according to a 16 September report, “Prepare and inspire: K-12 education in science, technology, engineering, and math (STEM) for America's future.” Noting that the United States lags behind other nations in STEM education at the elementary and secondary levels, the report, prepared by the President's Council of Advisors on Science and Technology, also recommends improving federal coordination and leadership on STEM education and supporting a state-led movement for shared standards in math and science. The release of the report coincides with President Barack Obama's announcement of the launch of Change the Equation, an organization that aims to help with math and science education. More information is available at http://www.whitehouse.gov/administration/eop/ostp and http://www.changetheequation.org/.

Design consideration for a nuclear electric propulsion system

NASA Technical Reports Server (NTRS)

Phillips, W. M.; Pawlik, E. V.

1978-01-01

A study is currently underway to design a nuclear electric propulsion vehicle capable of performing detailed exploration of the outer-planets. Primary emphasis is on the power subsystem. Secondary emphasis includes integration into a spacecraft, and integration with the thrust subsystem and science package or payload. The results of several design iterations indicate an all-heat-pipe system offers greater reliability, elimination of many technology development areas and a specific weight of under 20 kg/kWe at the 400 kWe power level. The system is compatible with a single Shuttle launch and provides greater safety than could be obtained with designs using pumped liquid metal cooling. Two configurations, one with the reactor and power conversion forward on the spacecraft with the ion engines aft and the other with reactor, power conversion and ion engines aft were selected as dual baseline designs based on minimum weight, minimum required technology development and maximum growth potential and flexibility.

Improving Scientific Communication and Publication Output in a Multidisciplinary Laboratory: Changing Culture Through Staff Development Workshops

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noonan, Christine F.; Stratton, Kelly G.

Communication plays a fundamental role in science and engineering disciplines. However, many higher education programs provide little, if any, technical communication coursework. Without strong communication skills scientists and engineers have less opportunity to publish, obtain competitive research funds, or grow their careers. This article describes the role of scientific communication training as an innovative staff development program in a learning-intensive workplace – a national scientific research and development laboratory. The findings show that involvement in the workshop has increased overall participating staff annual publications by an average of 61 percent compared to their pre-workshop publishing performance as well as confidencemore » level in their ability to write and publish peer-reviewed literature. Secondary benefits include improved information literacy skills and the development of informal communities of practice. This work provides insight into adult education in the workplace.« less

Women in Engineering--Beyond Recruitment. Proceedings of the Conference (Cornell University, Ithaca, New York, June 22-25, 1975).

ERIC Educational Resources Information Center

Ott, Mary Diederich, Ed.; Reese, Nancy A., Ed.

This report contains invited papers and comments from a conference on the status and problems of women in engineering. First, a discussion of research reveals that most women choose engineering as a field for college study late in their secondary education, depend heavily on external sources of support, and have attitudes and experiences different…

Translation efficiency of heterologous proteins is significantly affected by the genetic context of RBS sequences in engineered cyanobacterium Synechocystis sp. PCC 6803.

PubMed

Thiel, Kati; Mulaku, Edita; Dandapani, Hariharan; Nagy, Csaba; Aro, Eva-Mari; Kallio, Pauli

2018-03-02

Photosynthetic cyanobacteria have been studied as potential host organisms for direct solar-driven production of different carbon-based chemicals from CO 2 and water, as part of the development of sustainable future biotechnological applications. The engineering approaches, however, are still limited by the lack of comprehensive information on most optimal expression strategies and validated species-specific genetic elements which are essential for increasing the intricacy, predictability and efficiency of the systems. This study focused on the systematic evaluation of the key translational control elements, ribosome binding sites (RBS), in the cyanobacterial host Synechocystis sp. PCC 6803, with the objective of expanding the palette of tools for more rigorous engineering approaches. An expression system was established for the comparison of 13 selected RBS sequences in Synechocystis, using several alternative reporter proteins (sYFP2, codon-optimized GFPmut3 and ethylene forming enzyme) as quantitative indicators of the relative translation efficiencies. The set-up was shown to yield highly reproducible expression patterns in independent analytical series with low variation between biological replicates, thus allowing statistical comparison of the activities of the different RBSs in vivo. While the RBSs covered a relatively broad overall expression level range, the downstream gene sequence was demonstrated in a rigorous manner to have a clear impact on the resulting translational profiles. This was expected to reflect interfering sequence-specific mRNA-level interaction between the RBS and the coding region, yet correlation between potential secondary structure formation and observed translation levels could not be resolved with existing in silico prediction tools. The study expands our current understanding on the potential and limitations associated with the regulation of protein expression at translational level in engineered cyanobacteria. The acquired information can be used for selecting appropriate RBSs for optimizing over-expression constructs or multicistronic pathways in Synechocystis, while underlining the complications in predicting the activity due to gene-specific interactions which may reduce the translational efficiency for a given RBS-gene combination. Ultimately, the findings emphasize the need for additional characterized insulator sequence elements to decouple the interaction between the RBS and the coding region for future engineering approaches.

View forward from secondary bridge; note stack for venting after ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View forward from secondary bridge; note stack for venting after boilers, ventilators, davits, searchlights on port and starboard stanchions and ship's pulling boats; skylight at lower center provides light to engine room. (p30) - USS Olympia, Penn's Landing, 211 South Columbus Boulevard, Philadelphia, Philadelphia County, PA

Mathematical Modelling at Secondary School: The MACSI-Clongowes Wood College Experience

ERIC Educational Resources Information Center

Charpin, J. P. F.; O'Hara, S.; Mackey, D.

2013-01-01

In Ireland, to encourage the study of STEM (science, technology, engineering and mathematics) subjects and particularly mathematics, the Mathematics Applications Consortium for Science and Industry (MACSI) and Clongowes Wood College (County Kildare, Ireland) organized a mathematical modelling workshop for senior cycle secondary school students.…

Optical Evaluation of an As-Manufactured Compound Secondary Concentrator

NASA Technical Reports Server (NTRS)

Jaworske, Donald A.; Skowronski, Timothy J.; Miles, Barry J.

1999-01-01

Secondary concentrators are needed in solar thermal propulsion to further concentrate the energy collected by large lightweight primary concentrators. Although the physics of secondary concentrators has been worked out in detail and the manufacturing has been successfully completed for a ground demonstration, there is a need to quantify the specific performance of as-manufactured concentrators. This paper summarizes the properties of a secondary concentrator manufactured for the Integrated Solar Upper Stage engine ground demonstration in 1997 and presents data obtained from the optic that describe the performance of the as-manufactured component.

Automated Extraction of Secondary Flow Features

NASA Technical Reports Server (NTRS)

Dorney, Suzanne M.; Haimes, Robert

2005-01-01

The use of Computational Fluid Dynamics (CFD) has become standard practice in the design and development of the major components used for air and space propulsion. To aid in the post-processing and analysis phase of CFD many researchers now use automated feature extraction utilities. These tools can be used to detect the existence of such features as shocks, vortex cores and separation and re-attachment lines. The existence of secondary flow is another feature of significant importance to CFD engineers. Although the concept of secondary flow is relatively understood there is no commonly accepted mathematical definition for secondary flow. This paper will present a definition for secondary flow and one approach for automatically detecting and visualizing secondary flow.

At-Risk Learner Preference in Engineering/Technical Graphics: An Exploratory Study

ERIC Educational Resources Information Center

Ernst, Jeremy V.

2011-01-01

This exploratory study investigated learner preferences of secondary Career and Technical Education (CTE) Engineering/Technical Graphics students using the VARK Questionnaire. The VARK Questionnaire is an instrument that assists in determining students' dominant preferred learning styles, whether visual, aural, reading, or kinesthetic. This study…

Prototype design of a collision protection system for cab car engineers.

DOT National Transportation Integrated Search

2013-03-01

The objective of this project was to develop and analyze a passive system to protect a cab car engineer from secondary impact injuries that might be experienced due to impact with the cab console. The primary requirement for the system was the abilit...

Computer-Based Adaptation Tool for Advanced Diesel Engines Used in Military Applications

DTIC Science & Technology

2008-09-04

Scholarships. 4. Rupinder Kumar Sharma , MS in Mechanical Engineering, “Performance of EGR Cooling Device”, May 2006. 5. Rajesh Patel, MS in...secondary motions and hydrodynamic lubrication regime in a single cylinder internal combustion engine”. 9. Vijay K. Venugopal, MS in Mechanical

Exposure of BALB/c Mice to Diesel Engine Exhaust Origin Secondary Organic Aerosol (DE-SOA) during the Developmental Stages Impairs the Social Behavior in Adult Life of the Males.

PubMed

Win-Shwe, Tin-Tin; Kyi-Tha-Thu, Chaw; Moe, Yadanar; Fujitani, Yuji; Tsukahara, Shinji; Hirano, Seishiro

2015-01-01

Secondary organic aerosol (SOA) is a component of particulate matter (PM) 2.5 and formed in the atmosphere by oxidation of volatile organic compounds. Recently, we have reported that inhalation exposure to diesel engine exhaust (DE) originated SOA (DE-SOA) affect novel object recognition ability and impair maternal behavior in adult mice. However, it is not clear whether early life exposure to SOA during the developmental stages affect social behavior in adult life or not. In the present study, to investigate the effects of early life exposure to DE-SOA during the gestational and lactation stages on the social behavior in the adult life, BALB/c mice were exposed to clean air (control), DE, DE-SOA and gas without any PM in the inhalation chambers from gestational day 14 to postnatal day 21 for 5 h a day and 5 days per week. Then adult mice were examined for changes in their social behavior at the age of 13 week by a sociability and social novelty preference, social interaction with a juvenile mouse and light-dark transition test, hypothalamic mRNA expression levels of social behavior-related genes, estrogen receptor-alpha and oxytocin receptor as well as of the oxidative stress marker gene, heme oxygenase (HO)-1 by real-time RT-PCR method. In addition, hypothalamic level of neuronal excitatory marker, glutamate was determined by ELISA method. We observed that sociability and social novelty preference as well as social interaction were remarkably impaired, expression levels of estrogen receptor-alpha, oxytocin receptor mRNAs were significantly decreased, expression levels of HO-1 mRNAs and glutamate levels were significantly increased in adult male mice exposed to DE-SOA compared to the control ones. Findings of this study indicate early life exposure of BALB/c mice to DE-SOA may affect their late-onset hypothalamic expression of social behavior related genes, trigger neurotoxicity and impair social behavior in the males.

Exposure of BALB/c Mice to Diesel Engine Exhaust Origin Secondary Organic Aerosol (DE-SOA) during the Developmental Stages Impairs the Social Behavior in Adult Life of the Males

PubMed Central

Win-Shwe, Tin-Tin; Kyi-Tha-Thu, Chaw; Moe, Yadanar; Fujitani, Yuji; Tsukahara, Shinji; Hirano, Seishiro

2016-01-01

Secondary organic aerosol (SOA) is a component of particulate matter (PM) 2.5 and formed in the atmosphere by oxidation of volatile organic compounds. Recently, we have reported that inhalation exposure to diesel engine exhaust (DE) originated SOA (DE-SOA) affect novel object recognition ability and impair maternal behavior in adult mice. However, it is not clear whether early life exposure to SOA during the developmental stages affect social behavior in adult life or not. In the present study, to investigate the effects of early life exposure to DE-SOA during the gestational and lactation stages on the social behavior in the adult life, BALB/c mice were exposed to clean air (control), DE, DE-SOA and gas without any PM in the inhalation chambers from gestational day 14 to postnatal day 21 for 5 h a day and 5 days per week. Then adult mice were examined for changes in their social behavior at the age of 13 week by a sociability and social novelty preference, social interaction with a juvenile mouse and light-dark transition test, hypothalamic mRNA expression levels of social behavior-related genes, estrogen receptor-alpha and oxytocin receptor as well as of the oxidative stress marker gene, heme oxygenase (HO)-1 by real-time RT-PCR method. In addition, hypothalamic level of neuronal excitatory marker, glutamate was determined by ELISA method. We observed that sociability and social novelty preference as well as social interaction were remarkably impaired, expression levels of estrogen receptor-alpha, oxytocin receptor mRNAs were significantly decreased, expression levels of HO-1 mRNAs and glutamate levels were significantly increased in adult male mice exposed to DE-SOA compared to the control ones. Findings of this study indicate early life exposure of BALB/c mice to DE-SOA may affect their late-onset hypothalamic expression of social behavior related genes, trigger neurotoxicity and impair social behavior in the males. PMID:26834549

Flow of GE90 Turbofan Engine Simulated

NASA Technical Reports Server (NTRS)

Veres, Joseph P.

1999-01-01

The objective of this task was to create and validate a three-dimensional model of the GE90 turbofan engine (General Electric) using the APNASA (average passage) flow code. This was a joint effort between GE Aircraft Engines and the NASA Lewis Research Center. The goal was to perform an aerodynamic analysis of the engine primary flow path, in under 24 hours of CPU time, on a parallel distributed workstation system. Enhancements were made to the APNASA Navier-Stokes code to make it faster and more robust and to allow for the analysis of more arbitrary geometry. The resulting simulation exploited the use of parallel computations by using two levels of parallelism, with extremely high efficiency.The primary flow path of the GE90 turbofan consists of a nacelle and inlet, 49 blade rows of turbomachinery, and an exhaust nozzle. Secondary flows entering and exiting the primary flow path-such as bleed, purge, and cooling flows-were modeled macroscopically as source terms to accurately simulate the engine. The information on these source terms came from detailed descriptions of the cooling flow and from thermodynamic cycle system simulations. These provided boundary condition data to the three-dimensional analysis. A simplified combustor was used to feed boundary conditions to the turbomachinery. Flow simulations of the fan, high-pressure compressor, and high- and low-pressure turbines were completed with the APNASA code.

The Development of the STEM Career Interest Survey (STEM-CIS)

NASA Astrophysics Data System (ADS)

Kier, Meredith W.; Blanchard, Margaret R.; Osborne, Jason W.; Albert, Jennifer L.

2014-06-01

Internationally, efforts to increase student interest in science, technology, engineering, and mathematics (STEM) careers have been on the rise. It is often the goal of such efforts that increased interest in STEM careers should stimulate economic growth and enhance innovation. Scientific and educational organizations recommend that efforts to interest students in STEM majors and careers begin at the middle school level, a time when students are developing their own interests and recognizing their academic strengths. These factors have led scholars to call for instruments that effectively measure interest in STEM classes and careers, particularly for middle school students. In response, we leveraged the social cognitive career theory to develop a survey with subscales in science, technology, engineering, and mathematics. In this manuscript, we detail the six stages of development of the STEM Career Interest Survey. To investigate the instrument's reliability and psychometric properties, we administered this 44-item survey to over 1,000 middle school students (grades 6-8) who primarily were in rural, high-poverty districts in the southeastern USA. Confirmatory factor analyses indicate that the STEM-CIS is a strong, single factor instrument and also has four strong, discipline-specific subscales, which allow for the science, technology, engineering, and mathematics subscales to be administered separately or in combination. This instrument should prove helpful in research, evaluation, and professional development to measure STEM career interest in secondary level students.

Evaluation of coated columbium test panels having application to a secondary nozzle extension for the RL10 rocket engine system, parts 1 and 2

NASA Technical Reports Server (NTRS)

Murphy, Kenneth S.; Castro, Joaquin H.

1988-01-01

The activity performed on the screening and evaluation of various coatings for application on columbium alloy test panels representative of a radiation-cooled nozzle extension for the RL10 rocket engine is summarized. Vendors and processes of candidate coatings were evaluated. Post engine test evaluations of the two selected coatings are discussed.

What do K-12 students feel when dealing with technology and engineering issues? Gardner's multiple intelligence theory implications in technology lessons for motivating engineering vocations at Spanish Secondary School

NASA Astrophysics Data System (ADS)

Sánchez-Martín, Jesús; Álvarez-Gragera, García J.; Dávila-Acedo, M. Antonia; Mellado, Vicente

2017-11-01

The interest on engineering and scientific studies can be raised up even from the early years of academic instructional process. This vocation may be linked to emotions and aptitudes towards technological education. Particularly, students get in touch with these technological issues (namely STEM) during the Compulsory Secondary Education in Spain (12-16 years old).This work presents a preliminary evaluation of how relevant is Gardner's multiple intelligence theory (MIT) in the teaching-learning process within the Technology Lessons. In this sense, MIT was considered as an explanation variable of the emotional response within the different educational parts (so-called syllabus units, SU) in the Technology spanish curriculum. Different intelligence style (IS) will orient the student to a vision of the engineering and technology. This work tries to identify which relationships can be established between IS and specific technology and engineering learning. This research involved up to 135 students were subsequently tested about their predominant (IS) and on the emotions that arouse in them when working with each SU. The results were statistically significant and only those with a Logic-arithmetic or Environmental IS were not affected by the SU.Best teaching and learning practicesare required for encouraging further engineering studies.

Effect of Thermal and Chemical Treatment on the Microstructural, Mechanical and Machining Performance of W319 Al-Si-Cu Cast Alloy Engine Blocks and Directionally Solidified Machinability Test Blocks

NASA Astrophysics Data System (ADS)

Szablewski, Daniel

The research presented in this work is focused on making a link between casting microstructural, mechanical and machining properties for 319 Al-Si sand cast components. In order to achieve this, a unique Machinability Test Block (MTB) is designed to simulate the Nemak V6 Al-Si engine block solidification behavior. This MTB is then utilized to cast structures with in-situ nano-alumina particle master alloy additions that are Mg based, as well as independent in-situ Mg additions, and Sr additions to the MTB. The Universal Metallurgical Simulator and Analyzer (UMSA) Technology Platform is utilized for characterization of each cast structure at different Secondary Dendrite Arm Spacing (SDAS) levels. The rapid quench method and Jominy testing is used to assess the capability of the nano-alumina master alloy to modify the microstructure at different SDAS levels. Mechanical property assessment of the MTB is done at different SDAS levels on cast structures with master alloy additions described above. Weibull and Quality Index statistical analysis tools are then utilized to assess the mechanical properties. The MTB is also used to study single pass high speed face milling and bi-metallic cutting operations where the Al-Si hypoeutectic structure is combined with hypereutectoid Al-Si liners and cast iron cylinder liners. These studies are utilized to aid the implementation of Al-Si liners into the Nemak V6 engine block and bi-metallic cutting of the head decks. Machining behavior is also quantified for the investigated microstructures, and the Silicon Modification Level (SiML) is utilized for microstructural analysis as it relates to the machining behavior.

Turbulent Mixing of Primary and Secondary Flow Streams in a Rocket-Based Combined Cycle Engine

NASA Technical Reports Server (NTRS)

Cramer, J. M.; Greene, M. U.; Pal, S.; Santoro, R. J.; Turner, Jim (Technical Monitor)

2002-01-01

This viewgraph presentation gives an overview of the turbulent mixing of primary and secondary flow streams in a rocket-based combined cycle (RBCC) engine. A significant RBCC ejector mode database has been generated, detailing single and twin thruster configurations and global and local measurements. On-going analysis and correlation efforts include Marshall Space Flight Center computational fluid dynamics modeling and turbulent shear layer analysis. Potential follow-on activities include detailed measurements of air flow static pressure and velocity profiles, investigations into other thruster spacing configurations, performing a fundamental shear layer mixing study, and demonstrating single-shot Raman measurements.

75 FR 73050 - Office of Elementary and Secondary Education Overview Information; College Assistance Migrant...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-29

... priority is an invitational priority for applications that promote science, technology, engineering, and... Priority 1--Science, Technology, Engineering and Mathematics (STEM) Education: Projects that are designed... prepared for postsecondary or graduate study and careers in STEM, with a specific focus on an increase in...

Elements of Motivational Structure for Studying Mechanical Engineering

ERIC Educational Resources Information Center

Dubreta, Nikša; Miloš, Damir

2017-01-01

The article presents the findings on students' reasons for studying mechanical engineering. These reasons were covered in terms of extrinsic and intrinsic motivation additionally related to selected independent variables of the sample--students' secondary school Grade Point Average, their gender and the socio-economic status. The research was…

Richer Connections to Robotics through Project Personalization

ERIC Educational Resources Information Center

Veltman, Melanie; Davidson, Valerie; Deyell, Bethany

2012-01-01

In this work, we describe youth outreach activities carried out under the Chair for Women in Science and Engineering for Ontario (CWSE-ON) program. Specifically, we outline our design and implementation of robotics workshops to introduce and engage middle and secondary school students in engineering and computer science. Toward the goal of…

Science & Engineering Indicators--1993.

ERIC Educational Resources Information Center

National Science Foundation, Washington, DC. National Science Board.

This report provides policymakers in both the public and private sectors with a broad base of quantitative information about U.S. science and engineering (S&E) research and education and U.S. technology in a global context. Chapter 1, "Elementary and Secondary Science and Mathematics Education," discusses the student's achievement, interest,…

Basic Gasoline Engine Mechanics. Florida Vocational Program Guide.

ERIC Educational Resources Information Center

University of South Florida, Tampa. Dept. of Adult and Vocational Education.

This packet contains a program guide and Career Merit Achievement Plan (Career MAP) for the implementation of a basic gasoline engine mechanics program in Florida secondary and postsecondary schools. The program guide describes the program content and structure, provides a program description, lists job titles under the program, and includes a…

Computer Engineering Technology. Florida Vocational Program Guide.

ERIC Educational Resources Information Center

University of South Florida, Tampa. Dept. of Adult and Vocational Education.

This packet contains a program guide and Career Merit Achievement Plan (Career MAP) for the implementation of a computer engineering technology program in Florida secondary and postsecondary schools. The program guide describes the program content and structure, provides a program description, lists job titles under the program, and includes a…

322-R2U2 Engineering Assessment - August 2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abri, M.; Griffin, D.

This Engineering Assessment and Certification of Integrity of retention tank system 322-R2 has been prepared for tank systems that store and neutralizes hazardous waste and have secondary containment. The regulations require that this assessment be completed periodically and certified by an independent, qualified, California-registered professional engineer. Abri Environmental Engineering performed an inspection of the 322-R2 Tank system at the Lawrence Livermore National Laboratory (LLNL) in Livermore, CA. Mr. William W. Moore, P.E., conducted this inspection on March 16, 2015. Mr. Moore is a California Registered Civil Engineer, with extensive experience in civil engineering, and hazardous waste management.

Earth storable bimodal engine, phase 1

NASA Technical Reports Server (NTRS)

1973-01-01

An in-depth study of an Earth Storable Bimodal (ESB) Engine using earth storable propellants N2O/N2H4 and operating in either a monopropellant or bipropellant mode was conducted. Detailed studies were completed for both a hot-gas, regeneratively cooled thrust chamber and a ducted hot-gas, film cooled thrust chamber. Hydrazine decomposition products were used for cooling in either configuration. The various arrangements and configurations of hydrazine reactors, secondary injectors, chambers and gimbal methods were considered. The two basic materials selected for the major components were columbium alloys and L-605. The secondary injector types considered were previously demonstrated by JPL and consisted of a liquid-on-gas triplet, a liquid-on-gas doublet, and a liquid-on-gas coaxial injector. Various design tradeoffs were made with different reactor types located at: the secondary injector station, the thrust chamber throat, and the nozzle/extension interface. Associated thermal, structural, and mass analyses were completed.

Optimal Micro-Vane Flow Control for Compact Air Vehicle Inlets

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.; Miller, Daniel N.; Addington, Gregory A.; Agrell, Johan

2004-01-01

The purpose of this study on micro-vane secondary flow control is to demonstrate the viability and economy of Response Surface Methodology (RSM) to optimally design micro-vane secondary flow control arrays, and to establish that the aeromechanical effects of engine face distortion can also be included in the design and optimization process. These statistical design concepts were used to investigate the design characteristics of "low unit strength" micro-effector arrays. "Low unit strength" micro-effectors are micro-vanes set at very low angles-of-incidence with very long chord lengths. They were designed to influence the near wall inlet flow over an extended streamwise distance, and their advantage lies in low total pressure loss and high effectiveness in managing engine face distortion. Therefore, this report examines optimal micro-vane secondary flow control array designs for compact inlets through a Response Surface Methodology.

Analysis of Efficiency of the Ship Propulsion System with Thermochemical Recuperation of Waste Heat

NASA Astrophysics Data System (ADS)

Cherednichenko, Oleksandr; Serbin, Serhiy

2018-03-01

One of the basic ways to reduce polluting emissions of ship power plants is application of innovative devices for on-board energy generation by means of secondary energy resources. The combined gas turbine and diesel engine plant with thermochemical recuperation of the heat of secondary energy resources has been considered. It is suggested to conduct the study with the help of mathematical modeling methods. The model takes into account basic physical correlations, material and thermal balances, phase equilibrium, and heat and mass transfer processes. The paper provides the results of mathematical modeling of the processes in a gas turbine and diesel engine power plant with thermochemical recuperation of the gas turbine exhaust gas heat by converting a hydrocarbon fuel. In such a plant, it is possible to reduce the specific fuel consumption of the diesel engine by 20%. The waste heat potential in a gas turbine can provide efficient hydrocarbon fuel conversion at the ratio of powers of the diesel and gas turbine engines being up to 6. When the diesel engine and gas turbine operate simultaneously with the use of the LNG vapor conversion products, the efficiency coefficient of the plant increases by 4-5%.

High NO2/NOx emissions downstream of the catalytic diesel particulate filter: An influencing factor study.

PubMed

He, Chao; Li, Jiaqiang; Ma, Zhilei; Tan, Jianwei; Zhao, Longqing

2015-09-01

Diesel vehicles are responsible for most of the traffic-related nitrogen oxide (NOx) emissions, including nitric oxide (NO) and nitrogen dioxide (NO2). The use of after-treatment devices increases the risk of high NO2/NOx emissions from diesel engines. In order to investigate the factors influencing NO2/NOx emissions, an emission experiment was carried out on a high pressure common-rail, turbocharged diesel engine with a catalytic diesel particulate filter (CDPF). NO2 was measured by a non-dispersive ultraviolet analyzer with raw exhaust sampling. The experimental results show that the NO2/NOx ratios downstream of the CDPF range around 20%-83%, which are significantly higher than those upstream of the CDPF. The exhaust temperature is a decisive factor influencing the NO2/NOx emissions. The maximum NO2/NOx emission appears at the exhaust temperature of 350°C. The space velocity, engine-out PM/NOx ratio (mass based) and CO conversion ratio are secondary factors. At a constant exhaust temperature, the NO2/NOx emissions decreased with increasing space velocity and engine-out PM/NOx ratio. When the CO conversion ratios range from 80% to 90%, the NO2/NOx emissions remain at a high level. Copyright © 2015. Published by Elsevier B.V.

Bioengineering of plant (tri)terpenoids: from metabolic engineering of plants to synthetic biology in vivo and in vitro.

PubMed

Moses, Tessa; Pollier, Jacob; Thevelein, Johan M; Goossens, Alain

2013-10-01

Terpenoids constitute a large and diverse class of natural products that serve many functions in nature. Most of the tens of thousands of the discovered terpenoids are synthesized by plants, where they function as primary metabolites involved in growth and development, or as secondary metabolites that optimize the interaction between the plant and its environment. Several plant terpenoids are economically important molecules that serve many applications as pharmaceuticals, pesticides, etc. Major challenges for the commercialization of plant-derived terpenoids include their low production levels in planta and the continuous demand of industry for novel molecules with new or superior biological activities. Here, we highlight several synthetic biology methods to enhance and diversify the production of plant terpenoids, with a foresight towards triterpenoid engineering, the least engineered class of bioactive terpenoids. Increased or cheaper production of valuable triterpenoids may be obtained by 'classic' metabolic engineering of plants or by heterologous production of the compounds in other plants or microbes. Novel triterpenoid structures can be generated through combinatorial biosynthesis or directed enzyme evolution approaches. In its ultimate form, synthetic biology may lead to the production of large amounts of plant triterpenoids in in vitro systems or custom-designed artificial biological systems. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

78 FR 65715 - Request for Comments on the Program Solicitation for the Advanced Technological Education Program...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-01

... academic institutions and industry to promote improvement in the education of science and engineering...; professional development of college faculty and secondary school teachers; career pathways to two-year colleges from secondary schools and from two-year colleges to four-year institutions; career pathways that lead...

The Relationship between Self-Efficacy and Advanced STEM Coursework in Female Secondary Students

ERIC Educational Resources Information Center

Bernasconi, Bethany

2017-01-01

Despite years of attention, gender inequity persists in science, technology, engineering, and mathematics (STEM). Female STEM faculty, positive social interactions, and enrollment in advanced STEM secondary coursework are supportive factors in promoting female students' persistence in STEM fields. To address the gap in understanding these factors,…

Gender in higher level education and professional training in water supply and sanitation.

PubMed

Borba, M

1997-01-01

While more women are participating in training and decision-making in the local-level drinking water and sanitation sectors, this is not occurring at higher levels because of the gender imbalance that remains in higher-level sector education and professional training programs. This imbalance is characterized by gender-biased science curricula and by a lack of female role models. Even in developing countries where female enrollment outstrips that of men in higher education, women commonly prepare for careers in areas that are less valued than sanitary engineering. This imbalance ignores the fact that women can perform technical and managerial skills as competently as men. A similar male-dominated pattern emerges in professional training courses offered by development agencies, especially courses that focus on management issues. Low female school attendance begins when girls must forego primary school attendance to help their mothers in domestic chores, such as fetching water. Inadequate sanitation facilities for girls at schools also pose impediments. Efforts to improve this situation include 1) a promotional brochure developed by the Botswana Ministry of Education to raise awareness of the importance of men's and women's work as technicians and engineers in the water and sanitation sector among secondary school students; 2) creation of free schools and universities in Oman, where the numbers of women in previously male-dominated jobs are increasing; and 3) promotion of female education at the Asian Institute of Technology.

Advancing secondary metabolite biosynthesis in yeast with synthetic biology tools.

PubMed

Siddiqui, Michael S; Thodey, Kate; Trenchard, Isis; Smolke, Christina D

2012-03-01

Secondary metabolites are an important source of high-value chemicals, many of which exhibit important pharmacological properties. These valuable natural products are often difficult to synthesize chemically and are commonly isolated through inefficient extractions from natural biological sources. As such, they are increasingly targeted for production by biosynthesis from engineered microorganisms. The budding yeast species Saccharomyces cerevisiae has proven to be a powerful microorganism for heterologous expression of biosynthetic pathways. S. cerevisiae's usefulness as a host organism is owed in large part to the wealth of knowledge accumulated over more than a century of intense scientific study. Yet many challenges are currently faced in engineering yeast strains for the biosynthesis of complex secondary metabolite production. However, synthetic biology is advancing the development of new tools for constructing, controlling, and optimizing complex metabolic pathways in yeast. Here, we review how the coupling between yeast biology and synthetic biology is advancing the use of S. cerevisiae as a microbial host for the construction of secondary metabolic pathways. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

A Robust Design Methodology for Optimal Microscale Secondary Flow Control in Compact Inlet Diffusers

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.; Keller, Dennis J.

2001-01-01

It is the purpose of this study to develop an economical Robust design methodology for microscale secondary flow control in compact inlet diffusers. To illustrate the potential of economical Robust Design methodology, two different mission strategies were considered for the subject inlet, namely Maximum Performance and Maximum HCF Life Expectancy. The Maximum Performance mission maximized total pressure recovery while the Maximum HCF Life Expectancy mission minimized the mean of the first five Fourier harmonic amplitudes, i.e., 'collectively' reduced all the harmonic 1/2 amplitudes of engine face distortion. Each of the mission strategies was subject to a low engine face distortion constraint, i.e., DC60<0.10, which is a level acceptable for commercial engines. For each of these missions strategies, an 'Optimal Robust' (open loop control) and an 'Optimal Adaptive' (closed loop control) installation was designed over a twenty degree angle-of-incidence range. The Optimal Robust installation used economical Robust Design methodology to arrive at a single design which operated over the entire angle-of-incident range (open loop control). The Optimal Adaptive installation optimized all the design parameters at each angle-of-incidence. Thus, the Optimal Adaptive installation would require a closed loop control system to sense a proper signal for each effector and modify that effector device, whether mechanical or fluidic, for optimal inlet performance. In general, the performance differences between the Optimal Adaptive and Optimal Robust installation designs were found to be marginal. This suggests, however, that Optimal Robust open loop installation designs can be very competitive with Optimal Adaptive close loop designs. Secondary flow control in inlets is inherently robust, provided it is optimally designed. Therefore, the new methodology presented in this paper, combined array 'Lower Order' approach to Robust DOE, offers the aerodynamicist a very viable and economical way of exploring the concept of Robust inlet design, where the mission variables are brought directly into the inlet design process and insensitivity or robustness to the mission variables becomes a design objective.

Loss Estimations due to Earthquakes and Secondary Technological Hazards

NASA Astrophysics Data System (ADS)

Frolova, N.; Larionov, V.; Bonnin, J.

2009-04-01

Expected loss and damage assessment due to natural and technological disasters are of primary importance for emergency management just after the disaster, as well as for development and implementation of preventive measures plans. The paper addresses the procedures and simulation models for loss estimations due to strong earthquakes and secondary technological accidents. The mathematical models for shaking intensity distribution, damage to buildings and structures, debris volume, number of fatalities and injuries due to earthquakes and technological accidents at fire and chemical hazardous facilities are considered, which are used in geographical information systems assigned for these purposes. The criteria of technological accidents occurrence are developed on the basis of engineering analysis of past events' consequences. The paper is providing the results of scenario earthquakes consequences estimation and individual seismic risk assessment taking into account the secondary technological hazards at regional and urban levels. The individual risk is understood as the probability of death (or injuries) due to possible hazardous event within one year in a given territory. It is determined through mathematical expectation of social losses taking into account the number of inhabitants in the considered settlement and probability of natural and/or technological disaster.

Relationships Among Teacher Preparedness and Instructional Approaches to Secondary Student Achievement in STEM: A Secondary Analysis of TIMSS Data

NASA Astrophysics Data System (ADS)

Miller-Ricks, Karen A.

Educational reform efforts in Science, Technology, Engineering, Math (STEM) place emphasis on teachers as conduits for student achievement. The purpose of this study was to use TIMSS 2011 data to examine relationships between Science-Technology-Society (STS) instructional practices (student-centered instruction established to promote learning through real-world applications) teacher preparedness, and student achievement and identify variations of achievement between and among eighth-grade science and math classes. The research was framed by both Harper's Anti-Deficit Achievement Theory and Bronfenbrenner's Ecological Systems Theory (BEST). 501 U.S. schools contributed to the TIMSS 2011 data from both the teacher questionnaires and student booklets. Chi-Square, Spearman Correlation, and 2-level hierarchical linear modeling (HLM) were used to analyze data about teachers' preparedness to teach science and math, frequency of using STS instructional practices, and student achievement. The chi-square null hypothesis for math teachers was rejected, providing the assumption that there was an association between the frequency of using STS instruction in math and teacher preparedness. However, the chi-square null hypothesis for science teachers failed to be rejected, providing the assumption that there was no significant association between the frequency of using STS instruction in science and science teacher preparedness. The Spearman Correlation revealed statistically positively significant differences between STS instruction and science achievement, as well as between teacher preparedness and science achievement. The HLM results suggested that 33% of the variance of mathematics achievement was at the individual level and 66% was at the group level. The results for science teachers suggested that 54% of the variance of science achievement was at the individual level and 46% of the variance was at the group level. The data findings support the conclusion that secondary STEM teachers who are more prepared to teach within the STEM content domains and implement STS instructional practices into lessons have higher achievement scores.

Experimental and analytical study of secondary path variations in active engine mounts

NASA Astrophysics Data System (ADS)

Hausberg, Fabian; Scheiblegger, Christian; Pfeffer, Peter; Plöchl, Manfred; Hecker, Simon; Rupp, Markus

2015-03-01

Active engine mounts (AEMs) provide an effective solution to further improve the acoustic and vibrational comfort of passenger cars. Typically, adaptive feedforward control algorithms, e.g., the filtered-x-least-mean-squares (FxLMS) algorithm, are applied to cancel disturbing engine vibrations. These algorithms require an accurate estimate of the AEM active dynamic characteristics, also known as the secondary path, in order to guarantee control performance and stability. This paper focuses on the experimental and theoretical study of secondary path variations in AEMs. The impact of three major influences, namely nonlinearity, change of preload and component temperature, on the AEM active dynamic characteristics is experimentally analyzed. The obtained test results are theoretically investigated with a linear AEM model which incorporates an appropriate description for elastomeric components. A special experimental set-up extends the model validation of the active dynamic characteristics to higher frequencies up to 400 Hz. The theoretical and experimental results show that significant secondary path variations are merely observed in the frequency range of the AEM actuator's resonance frequency. These variations mainly result from the change of the component temperature. As the stability of the algorithm is primarily affected by the actuator's resonance frequency, the findings of this paper facilitate the design of AEMs with simpler adaptive feedforward algorithms. From a practical point of view it may further be concluded that algorithmic countermeasures against instability are only necessary in the frequency range of the AEM actuator's resonance frequency.

''Math in a Can'': Teaching Mathematics and Engineering Design

ERIC Educational Resources Information Center

Narode, Ronald B.

2011-01-01

Using an apparently simple problem, ''Design a cylindrical can that will hold a liter of milk,'' this paper demonstrates how engineering design may facilitate the teaching of the following ideas to secondary students: linear and non-linear relationships; basic geometry of circles, rectangles, and cylinders; unit measures of area and volume;…

Pathways to an Engineering Career

ERIC Educational Resources Information Center

Pearson, Willie, Jr.; Miller, Jon D.

2012-01-01

Utilizing data from the 20-year record of the Longitudinal Study of American Youth (LSAY), this analysis uses a set of variables to predict employment in engineering for a national sample of adults aged 34 to 37. The LSAY is one of the longest longitudinal studies of the impact of secondary education and postsecondary education conducted in the…

Reasons and Motivations for the Option of an Engineering Career in Portugal

ERIC Educational Resources Information Center

Dias, Diana

2011-01-01

Towards the end of their secondary education, students face significant pressures in their decision about their career plan. These pressures are internal and external, personal and social, individual and from the reference group. This paper aims at understanding the reasons driving engineering students' choices, their perceived needs and…

Secondary Students' Conceptual Understanding of Engineering as a Field

ERIC Educational Resources Information Center

Montfort, Devlin B.; Brown, Shane; Whritenour, Victoria

2013-01-01

Researchers have long been interested in how to recruit and retain more and more diverse students into engineering programs. One consistent challenge in this research is understanding the impacts of interventions from the point of view of the student, and how their preconceptions may influence that effectiveness. This study investigated how…

Toward Epistemologically Authentic Engineering Design Activities in the Science Classroom

ERIC Educational Resources Information Center

Leonard, Mary J.

2004-01-01

In recent years educators and educational researchers in the U.S. have begun to introduce engineering design activities in secondary science classrooms for the purpose of scaffolding science learning as well as supporting such general problem-solving skills as decision making and working in teams. However, such curricula risk perpetuating a…

How Safe Are Kid-Safe Search Engines?

ERIC Educational Resources Information Center

Masterson-Krum, Hope

2001-01-01

Examines search tools available to elementary and secondary school students, both human-compiled and crawler-based, to help direct them to age-appropriate Web sites; analyzes the procedures of search engines labeled family-friendly or kid safe that use filters; and tests the effectiveness of these services to students in school libraries. (LRW)

Instructional Improvement and Student Engagement in Post-Secondary Engineering Courses: The Complexity Underlying Small Effect Sizes

ERIC Educational Resources Information Center

Hilpert, Jonathan C.; Husman, Jenefer

2017-01-01

The current study leveraged a professional development programme for engineering faculty at a large research university to examine the impact of instructional improvement on student engagement. Professors who participated in the professional development were observed three times and rated using an existing observation protocol. Students in courses…

Science and Engineering Education for the 1980s and Beyond.

ERIC Educational Resources Information Center

Department of Education, Washington, DC.

Prepared by the National Science Foundation and the Department of Education in response to a request by President Carter for information on the condition of science and engineering education in America, this document contains data showing a decline in the general understanding of science and technology among secondary school students. Although…

A Review of the IEE's Involvement in Academic Gaming.

ERIC Educational Resources Information Center

Ellington, H. I.; And Others

In partnership with the Institute of Technology in Aberdeen, the Institution of Electrical Engineers (IEE) has pioneered the development of a range of highly sophisticated simulation games and case studies based on realistic engineering scenarios for use in secondary and higher education and industrial training. The initial involvement of IEE in…

Situating Teachers' Developmental Engineering Experiences in an Inquiry-Based, Laboratory Learning Environment

ERIC Educational Resources Information Center

Hardré, Patricia L.; Ling, Chen; Shehab, Randa L.; Nanny, Mark A.; Nollert, Matthias U.; Refai, Hazem; Ramseyer, Christopher; Herron, Jason; Wollega, Ebisa D.; Huang, Su-Min

2017-01-01

Many secondary math and science teachers don't understand the nature and application of engineering adequately to transfer that understanding to their students. Research is needed that investigates and illuminates the process and characteristics of development that addresses this gap. This mixed-method study examines the developmental experiences…

Teachers Learning to Prepare Future Engineers: A Systemic Analysis Through Five Components of Development and Transfer

ERIC Educational Resources Information Center

Hardré, Patricia L.; Ling, Chen; Shehab, Randa L.; Nanny, Mark A.; Refai, Hazem; Nollert, Matthias U.; Ramseyer, Christopher; Wollega, Ebisa D.; Huang, Su-Min; Herron, Jason

2018-01-01

This study used a systemic perspective to examine a five-component experiential process of perceptual and developmental growth, and transfer-to-teaching. Nineteen secondary math and science teachers participated in a year-long, engineering immersion and support experience, with university faculty mentors. Teachers identified critical shifts in…

Summer Study in Engineering for High School Women.

ERIC Educational Resources Information Center

Goldberg, Julie L.; Sedlacek, William E.

The transition between high school and college is a crucial point where many young women engaged in the applied sciences and engineering cease their participation. To help retain young women's interest and help bridge the gap between secondary school and higher education, The University of Maryland, College Park, held a six-week live-in academic…

Secondary Engineering Design Graphics Educator Service Load of Students with Identified Categorical Disabilities and Limited English Proficiency

ERIC Educational Resources Information Center

Ernst, Jeremy V.; Li, Songze; Williams, Thomas O.

2014-01-01

The ever-changing student population of engineering design graphics students necessitates broader sets of instructor adeptness. Specifically, preparedness to educate and provide adequate educational access to content for students with identified categorical disabilities and Limited English Proficiency (LEP) is now an essential readiness skill for…

Technology Education; Engineering Technology and Industrial Technology in California Community Colleges: A Curriculum Guide.

ERIC Educational Resources Information Center

Schon, James F.

In order to identify the distinguishing characteristics of technical education programs in engineering and industrial technology currently offered by post-secondary institutions in California, a body of data was collected by visiting 25 community colleges, 5 state universities, and 8 industrial firms; by a questionnaire sampling of 72 California…

Future Engineers: The Intrinsic Technology Motivation of Secondary School Pupils

ERIC Educational Resources Information Center

Jones, Lewis C. R.; McDermott, Hilary J.; Tyrer, John R.; Zanker, Nigel P.

2018-01-01

The supply of students motivated to study engineering in higher education is critical to the sector. Results are presented from the 'Mindsets STEM Enhancement Project.' Fifty-seven new resources packs, designed to improve STEM education in Design and Technology, were given to schools across London. A modified Intrinsic Motivation Inventory…

[Synthetic biology toward microbial secondary metabolites and pharmaceuticals].

PubMed

Wu, Lin-Zhuan; Hong, Bin

2013-02-01

Microbial secondary metabolites are one of the major sources of anti-bacterial, anti-fungal, antitumor, anti-virus and immunosuppressive agents for clinical use. Present challenges in microbial pharmaceutical development are the discovery of novel secondary metabolites with significant biological activities, improving the fermentation titers of industrial microbial strains, and production of natural product drugs by re-establishing their biosynthetic pathways in suitable microbial hosts. Synthetic biology, which is developed from systematic biology and metabolic engineering, provides a significant driving force for microbial pharmaceutical development. The review describes the major applications of synthetic biology in novel microbial secondary metabolite discovery, improved production of known secondary metabolites and the production of some natural drugs in genetically modified or reconstructed model microorganisms.

Experimental Measurements of the Effects of Photo-chemical Oxidation on Aerosol Emissions in Aircraft Exhaust

NASA Astrophysics Data System (ADS)

Miracolo, M. A.; Presto, A. A.; Hennigan, C. J.; Nguyen, N.; Ranjan, M.; Reeder, A.; Lipsky, E.; Donahue, N. M.; Robinson, A. L.

2009-12-01

Many military and commercial airfields are located in non-attainment areas for particulate matter (PM2.5), but the contribution of emissions from in-use aircraft to local and regional PM2.5 concentrations is uncertain. In collaboration with the Pennsylvania Air National Guard 171st Air Refueling Wing, the Carnegie Mellon University (CMU) Mobile Laboratory was deployed to measure fresh and aged emissions from a CFM56-2B1 gas-turbine engine mounted on a KC-135 Stratotanker airframe. The CFM-56 family of engine powers many different types of military and civilian aircraft, including the Boeing 737 and several Airbus models. It is one of the most widely deployed models of engines in the world. The goal of this work was to measure the gas-particle partitioning of the fresh emissions at atmospherically relevant conditions and to investigate the effect of atmospheric oxidation on aerosol loadings as the emissions age. Emissions were sampled from an inlet installed one meter downstream of the engine exit plane and transferred into a portable smog chamber via a heated inlet line. Separate experiments were conducted at different engine loads ranging from ground idle to take-off rated thrust. During each experiment, some diluted exhaust was added to the chamber and the volatility of the fresh emissions was then characterized using a thermodenuder. After this characterization, the chamber was exposed to either ambient sunlight or UV lights to initiate photochemical oxidation, which produced secondary aerosol and ozone. A suite of gas and particle-phase instrumentation was used to characterize the evolution of the gas and particle-phase emissions, including an aerosol mass spectrometer (AMS) to measure particle size and composition distributions. Fresh emissions of fine particles varied with engine load with peak emission factors at low and high loads. At high engine loads, the fresh emissions were dominated by black carbon; at low loads volatile organic carbon emissions were dominant. At low loads, photo-oxidation increased aerosol loadings in the chamber by a factor of fifty. We attribute this substantial secondary organic aerosol (SOA) production to oxidation of low-volatility organic vapors emitted under low loads. At higher loads, we see more modest secondary aerosol production from both organics and inorganics. Therefore secondary aerosol production can substantially exceed the direct aerosol emissions from aircraft. The results underscore the dramatic effects that photo-oxidation has on aerosol emissions from aircraft.

The Role of High School Racial Composition and Opportunities to Learn in Students' STEM College Participation

ERIC Educational Resources Information Center

Bottia, Martha Cecilia; Mickelson, Roslyn Arlin; Giersch, Jason; Stearns, Elizabeth; Moller, Stephanie

2018-01-01

We analyze longitudinal data from students who spent their academic careers in North Carolina (NC) public secondary schools and attended NC public universities to investigate the importance of high school racial composition and opportunities to learn in secondary school for choosing a science, technology, engineering, and mathematics (STEM) major.…

Effectiveness of Transformational Leadership Style in Secondary Schools in Nigeria

ERIC Educational Resources Information Center

Money, Veronica. O.

2017-01-01

Education is the engine of national growth. A population of well educated citizens increases national economic competitiveness. To survive and develop in any nation, the education industry must grow. Secondary schools in Nigeria are headed by Principal. They are regarded as the Chief Executive of the school and are held accountable for all that…

Using a Thinking Skills System to Guide Discussions during a Working Conference on Students with Disabilities Pursuing STEM Fields

ERIC Educational Resources Information Center

Rule, Audrey C.; Stefanich, Greg P.

2012-01-01

Students with sensory or motor disabilities are often dissuaded from pursuing science, technology, engineering, or mathematics (STEM) careers. They are frequently under-prepared to succeed in post-secondary STEM coursework because of inadequate high school preparation and limited post-secondary accommodations. A two-day working conference…

Education in acoustics in Argentina

NASA Astrophysics Data System (ADS)

Miyara, Federico

2002-11-01

Over the last decades, education in acoustics (EA) in Argentina has experienced ups and downs due to economic and political issues interfering with long term projects. Unlike other countries, like Chile, where EA has reached maturity in spite of the acoustical industry having shown little development, Argentina has several well-established manufacturers of acoustic materials and equipment but no specific career with a major in acoustics. At the university level, acoustics is taught as a complementary--often elective--course for careers such as architecture, communication engineering, or music. In spite of this there are several research centers with programs covering environmental and community noise, effects of noise on man, acoustic signal processing, musical acoustics and acoustic emission, and several national and international meetings are held each year in which results are communicated and discussed. Several books on a variety of topics such as sound system, architectural acoustics, and noise control have been published as well. Another chapter in EA is technical and vocational education, ranging between secondary and postsecondary levels, with technical training on sound system operation or design. Over the last years there have been several attempts to implement master degrees in acoustics or audio engineering, with little or no success.

Cyanobacteria: photosynthetic factories combining biodiversity, radiation resistance, and genetics to facilitate drug discovery.

PubMed

Cassier-Chauvat, Corinne; Dive, Vincent; Chauvat, Franck

2017-02-01

Cyanobacteria are ancient, abundant, and widely diverse photosynthetic prokaryotes, which are viewed as promising cell factories for the ecologically responsible production of chemicals. Natural cyanobacteria synthesize a vast array of biologically active (secondary) metabolites with great potential for human health, while a few genetic models can be engineered for the (low level) production of biofuels. Recently, genome sequencing and mining has revealed that natural cyanobacteria have the capacity to produce many more secondary metabolites than have been characterized. The corresponding panoply of enzymes (polyketide synthases and non-ribosomal peptide synthases) of interest for synthetic biology can still be increased through gene manipulations with the tools available for the few genetically manipulable strains. In this review, we propose to exploit the metabolic diversity and radiation resistance of cyanobacteria, and when required the genetics of model strains, for the production and radioactive ( 14 C) labeling of bioactive products, in order to facilitate the screening for new drugs.

Gendered Pathways: How Mathematics Ability Beliefs Shape Secondary and Postsecondary Course and Degree Field Choices

PubMed Central

Perez-Felkner, Lara; Nix, Samantha; Thomas, Kirby

2017-01-01

Do mathematics ability beliefs explain gender gaps in the physical science, engineering, mathematics, and computer science fields (PEMC) and other science fields? We leverage U.S. nationally representative longitudinal data to estimate gendered differences in girls' and boys' perceptions of mathematics ability with the most difficult or challenging material. Our analyses examine the potentially interacting effects of gender and these ability beliefs on students' pathways to scientific careers. Specifically, we study how beliefs about ability with challenging mathematics influence girls' and boys' choices to pursue PEMC degrees, evaluating educational milestones over a 6-year period: advanced science course completion in secondary school and postsecondary major retention and selection. Our findings indicate even at the same levels of observed ability, girls' mathematics ability beliefs under challenge are markedly lower than those of boys. These beliefs matter over time, potentially tripling girls' chances of majoring in PEMC sciences, over and above biological science fields, all else being equal. Implications and potential interventions are discussed. PMID:28428762

Gendered Pathways: How Mathematics Ability Beliefs Shape Secondary and Postsecondary Course and Degree Field Choices.

PubMed

Perez-Felkner, Lara; Nix, Samantha; Thomas, Kirby

2017-01-01

Do mathematics ability beliefs explain gender gaps in the physical science, engineering, mathematics, and computer science fields (PEMC) and other science fields? We leverage U.S. nationally representative longitudinal data to estimate gendered differences in girls' and boys' perceptions of mathematics ability with the most difficult or challenging material. Our analyses examine the potentially interacting effects of gender and these ability beliefs on students' pathways to scientific careers. Specifically, we study how beliefs about ability with challenging mathematics influence girls' and boys' choices to pursue PEMC degrees, evaluating educational milestones over a 6-year period: advanced science course completion in secondary school and postsecondary major retention and selection. Our findings indicate even at the same levels of observed ability, girls' mathematics ability beliefs under challenge are markedly lower than those of boys. These beliefs matter over time, potentially tripling girls' chances of majoring in PEMC sciences, over and above biological science fields, all else being equal. Implications and potential interventions are discussed.

Performance Increase Verification for a Bipropellant Rocket Engine

NASA Technical Reports Server (NTRS)

Alexander, Leslie; Chapman, Jack; Wilson, Reed; Krismer, David; Lu, Frank; Wilson, Kim; Miller, Scott; England, Chris

2008-01-01

Component performance assessment testing for a, pressure-fed earth storable bipropellant rocket engine was successfully completed at Aerojet's Redmond test facility. The primary goal of the this development project is to increase the specific impulse of an apogee class bi-propellant engine to greater than 330 seconds with nitrogen tetroxide and monomethylhydrazine propellants and greater than 335 seconds with nitrogen tetroxide and hydrazine. The secondary goal of the project is to take greater advantage of the high temperature capabilities of iridium/rhenium chambers. In order to achieve these goals, the propellant feed pressures were increased to 400 psia, nominal, which in turn increased the chamber pressure and temperature, allowing for higher c*. The tests article used a 24-on-24 unlike doublet injector design coupled with a copper heat sink chamber to simulate a flight configuration combustion chamber. The injector is designed to produce a nominal 200 lbf of thrust with a specific impulse of 335 seconds (using hydrazine fuel). Effect of Chamber length on engine C* performance was evaluated with the use of modular, bolt-together test hardware and removable chamber inserts. Multiple short duration firings were performed to characterize injector performance across a range of thrust levels, 180 to 220 lbf, and mixture ratios, from 1.1 to 1.3. During firing, ignition transient, chamber pressure, and various temperatures were measured in order to evaluate the performance of the engine and characterize the thermal conditions. The tests successfully demonstrated the stable operation and performance potential of a full scale engine with a measured c* of XXXX ft/sec (XXXX m/s) under nominal operational conditions.

Cause-Effect Analysis: Improvement of a First Year Engineering Students' Calculus Teaching Model

ERIC Educational Resources Information Center

van der Hoff, Quay; Harding, Ansie

2017-01-01

This study focuses on the mathematics department at a South African university and in particular on teaching of calculus to first year engineering students. The paper reports on a cause-effect analysis, often used for business improvement. The cause-effect analysis indicates that there are many factors that impact on secondary school teaching of…

25 Years Later: A History of the McClellan-Kerr Arkansas River Navigation System in Arkansas

DTIC Science & Technology

1995-01-01

and Clements, ’’Arkansas River ... Sediment Control," chap. 18, pp. 15-16; Ronald A. Antonino , "The Arkansas River Project," Civil Engineering (Dec...March 8, 1989. Secondary Sources Antonino , Ronald A. "The Arkansas River Project," Civil Engineering (Dec. 1969): 44- 49. Arnold, Morris S

An Engineer's View of Science Education. A Discussion Paper, D-81/2.

ERIC Educational Resources Information Center

George, Donald A.

Written as part of a series for the Science Council of Canada, this publication focuses on elementary and secondary school science education as it effects students in general and those pursuing engineering and technical careers in particular. Section one examines post-Sputnik science education and claims that an overly narrow emphasis on pure…

Mississippi Curriculum Framework for Diesel Equipment Repair & Service (Program CIP: 47.0605--Diesel Engine Mechanic & Repairer). Secondary Programs.

ERIC Educational Resources Information Center

Mississippi Research and Curriculum Unit for Vocational and Technical Education, State College.

This document, which reflects Mississippi's statutory requirement that instructional programs be based on core curricula and performance-based assessment, contains outlines of the instructional units required in local instructional management plans and daily lesson plans for diesel engine mechanics I and II. Presented first are a program…

A Study To Determine the Job Satisfaction of the Engineering/Industrial Technology Faculty at Delgado Community College.

ERIC Educational Resources Information Center

Satterlee, Brian

A study assessed job satisfaction among Engineering/Industrial Technology faculty at Delgado Community College (New Orleans, Louisiana). A secondary purpose was to confirm Herzberg's Two-Factor Theory of Job Satisfaction (1966) that workers derived satisfaction from the work itself and that causes of dissatisfaction stemmed from conditions…

Atmospheric impacts of black carbon emission reductions through the strategic use of biodiesel in California.

PubMed

Zhang, Hongliang; Magara-Gomez, Kento T; Olson, Michael R; Okuda, Tomoaki; Walz, Kenneth A; Schauer, James J; Kleeman, Michael J

2015-12-15

The use of biodiesel as a replacement for petroleum-based diesel fuel has gained interest as a strategy for greenhouse gas emission reductions, energy security, and economic advantage. Biodiesel adoption may also reduce particulate elemental carbon (EC) emissions from conventional diesel engines that are not equipped with after-treatment devices. This study examines the impact of biodiesel blends on EC emissions from a commercial off-road diesel engine and simulates the potential public health benefits and climate benefits. EC emissions from the commercial off-road engine decreased by 76% when ultra-low sulfur commercial diesel (ULSD) fuel was replaced by biodiesel. Model calculations predict that reduced EC emissions translate directly into reduced EC concentrations in the atmosphere, but the concentration of secondary particulate matter was not directly affected by this fuel change. Redistribution of secondary particulate matter components to particles emitted from other sources did change the size distribution and therefore deposition rates of those components. Modification of meteorological variables such as water content and temperature influenced secondary particulate matter formation. Simulations with a source-oriented WRF/Chem model (SOWC) for a severe air pollution episode in California that adopted 75% biodiesel blended with ULSD in all non-road diesel engines reduced surface EC concentrations by up to 50% but changed nitrate and total PM2.5 mass concentrations by less than ±5%. These changes in concentrations will have public health benefits but did not significantly affect radiative forcing at the top of the atmosphere. The removal of EC due to the adoption of biodiesel produced larger coatings of secondary particulate matter on other atmospheric particles containing residual EC leading to enhanced absorption associated with those particles. The net effect was a minor change in atmospheric optical properties despite a large change in atmospheric EC concentrations. These results emphasize the importance of considering EC mixing state in climate research. Copyright © 2015. Published by Elsevier B.V.

Fluvial engineering works in the river bed of the Middle Loire

NASA Astrophysics Data System (ADS)

Nabet, Fouzi

2010-05-01

Since 1995, the Loire riverbed has been a field of restoration and maintenance. These interventions took place within the Plan Loire Grandeur Nature and consisted of the following points: the protection of the inhabitants against flooding risks (opening of the secondary channels), the preservation of the ecological assets and the elimination of the sinking of the water line at it's lower level. This research occurred in a specific part of the Loire riverbed, which is situated between Nevers and Orleans (on both banks). We tried by using a geomorphologic analysis to put in evidence the impact of the interventions on the evolution of the secondary channels and dikes. The Geographical Information System (GIS) put in place for the studies sector helps the space analysis by the superposition and the comparison of the different layers of information. This information tool helps creating a database, which can be updated and extended. This way, the managers of this site can easily integrate new thematic (ecological, pedagogical, tourism activity…) and benefit from a precise mapping of the intervention's areas and the impact of the restoration works. The main objective of the PhD is to analyse the functioning of hydrological and fluvial dynamics of the river bed of the Middle Loire, particularly in areas covered by maintenance work. These fluvial engineering works aim to improve flow and transfer of sediment in the river bed. This approach will evaluate the effectiveness of such maintenance work. It is necessary to set up a very fine scale model to quantify sediment transfer between secondary and main channels. The situation of secondary channels is contrasted, but the excessive growth of vegetation in some channels triggers their perennial functioning. The fine scale analysis is based on studies on seasonal and inter-annual evolution of secondary channels. Digital Elevation models (DEM), longitudinal profiles and topographic cross-sections integrated GIS help to quantify precisely erosion and sedimentation, according to the hydrological year. This work should be conducted according to hydrological events on the basis of topographical, bathymetric and sedimentary surveys. Therefore, a limited number of sites has been chosen in collaboration with AITL, DIREN Centre, and Conservatoire des Espaces Naturels. The result of the thesis brings tools to the Loire river management.

Combustion Stability Characteristics of the Project Morpheus Liquid Oxygen/Liquid Methane Main Engine

NASA Technical Reports Server (NTRS)

Melcher, J. C.; Morehead, Robert L.

2014-01-01

The Project Morpheus liquid oxygen (LOX) / liquid methane rocket engines demonstrated acousticcoupled combustion instabilities during sea-level ground-based testing at the NASA Johnson Space Center (JSC) and Stennis Space Center (SSC). High-amplitude, 1T, 1R, 1T1R (and higher order) modes appear to be triggered by injector conditions. The instability occurred during the Morpheus-specific engine ignition/start sequence, and did demonstrate the capability to propagate into mainstage. However, the instability was never observed to initiate during mainstage, even at low power levels. The Morpheus main engine is a JSC-designed 5,000 lbf-thrust, 4:1 throttling, pressure-fed cryogenic engine using an impinging element injector design. Two different engine designs, named HD4 and HD5, and two different builds of the HD4 engine all demonstrated similar instability characteristics. Through the analysis of more than 200 hot fire tests on the Morpheus vehicle and SSC test stand, a relationship between ignition stability and injector/chamber pressure was developed. The instability has the distinct characteristic of initiating at high relative injection pressure drop (dP) at low chamber pressure (Pc); i.e., instabilities initiated at high dP/Pc at low Pc during the start sequence. The high dP/Pc during start results during the injector /chamber chill-in, and is enhanced by hydraulic flip in the injector orifice elements. Because of the fixed mixture ratio of the existing engine design (the main valves share a common actuator), it is not currently possible to determine if LOX or methane injector dP/Pc were individual contributors (i.e., LOX and methane dP/Pc typically trend in the same direction within a given test). The instability demonstrated initiation characteristic of starting at or shortly after methane injector chillin. Colder methane (e.g., sub-cooled) at the injector inlet prior to engine start was much more likely to result in an instability. A secondary effect of LOX sub-cooling was also possibly observed; greater LOX sub- cooling improved stability. Some tests demonstrated a low-amplitude 1L-1T instability prior to LOX injector chill-in. The Morpheus main engine also demonstrated chug instabilities during some engine shutdown sequences on the flight vehicle and SSC test stand. The chug instability was also infrequently observed during the startup sequence. The chug instabilities predictably initiated at low dP/Pc at low Pc. The chug instabilities were always self-limiting; startup chug instabilities terminated during throttle-up and shutdown chug instabilities decayed by shutdown termination.

Recent advances in reconstructing microbial secondary metabolites biosynthesis in Aspergillus spp.

PubMed

He, Yi; Wang, Bin; Chen, Wanping; Cox, Russell J; He, Jingren; Chen, Fusheng

High throughput genome sequencing has revealed a multitude of potential secondary metabolites biosynthetic pathways that remain cryptic. Pathway reconstruction coupled with genetic engineering via heterologous expression enables discovery of novel compounds, elucidation of biosynthetic pathways, and optimization of product yields. Apart from Escherichia coli and yeast, fungi, especially Aspergillus spp., are well known and efficient heterologous hosts. This review summarizes recent advances in heterologous expression of microbial secondary metabolite biosynthesis in Aspergillus spp. We also discuss the technological challenges and successes in regard to heterologous host selection and DNA assembly behind the reconstruction of microbial secondary metabolite biosynthesis. Copyright © 2018 Elsevier Inc. All rights reserved.

STEM Graduates and Secondary School Curriculum: Does Early Exposure to Science Matter? CEP Discussion Paper No. 1443

ERIC Educational Resources Information Center

De Philippis, Marta

2016-01-01

Increasing the number of Science, Technology, Engineering and Math (STEM) university graduates is considered a key element for long-term productivity and competitiveness in the global economy. Still, little is known about what actually drives and shapes students' choices. This paper focusses on secondary school students at the very top of the…

Post Secondary Project-Based Learning in Science, Technology, Engineering and Mathematics

ERIC Educational Resources Information Center

Ralph, Rachel A.

2015-01-01

Project-based learning (PjBL--to distinguish from problem-based learning--PBL) has become a recurrent practice in K-12 classroom environments. As PjBL has become prominent in K-12 classrooms, it has also surfaced in post-secondary institutions. The purpose of this paper is to examine the research that has studied a variety of science, technology,…

Problem Based Learning Technique and Its Effect on Acquisition of Linear Programming Skills by Secondary School Students in Kenya

ERIC Educational Resources Information Center

Nakhanu, Shikuku Beatrice; Musasia, Amadalo Maurice

2015-01-01

The topic Linear Programming is included in the compulsory Kenyan secondary school mathematics curriculum at form four. The topic provides skills for determining best outcomes in a given mathematical model involving some linear relationship. This technique has found application in business, economics as well as various engineering fields. Yet many…

Choices and Changes: Eccles' Expectancy-Value Model and Upper-Secondary School Students' Longitudinal Reflections about Their Choice of a STEM Education

ERIC Educational Resources Information Center

Lykkegaard, Eva; Ulriksen, Lars

2016-01-01

During the past 30 years, Eccles' comprehensive social-psychological Expectancy-Value Model of Motivated Behavioural Choices (EV-MBC model) has been proven suitable for studying educational choices related to Science, Technology, Engineering and/or Mathematics (STEM). The reflections of 15 students in their last year in upper-secondary school…

158. ARAIII Reactor building (ARA608) Secondary cooling loop and piping ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

158. ARA-III Reactor building (ARA-608) Secondary cooling loop and piping plan. This drawing was selected as a typical example of piping arrangements within reactor building. Aerojet/general 880-area/GCRE-608-P-16. Date: February 1958. INeel index code no. 063-0608-50-013-102641. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

A Survey of Best Practices and Key Learning Objectives for Successful Secondary School STEM Academy Settings

ERIC Educational Resources Information Center

Kasza, Paul; Slater, Timothy F.

2017-01-01

Specialized secondary schools in the United States focusing on Science, Technology, Engineering, and Math (STEM) are becoming commonplace in the United States. Such schools are generally referred to by U.S. teachers as Academies. In a purposeful effort to provide a resource to educators building new STEM Academies, this study provides both a…

High School Longitudinal Study of 2009 (HSLS:09): Base-Year Data File Documentation. NCES 2011-328

ERIC Educational Resources Information Center

Ingels, Steven J.; Pratt, Daniel J.; Herget, Deborah R.; Burns, Laura J.; Dever, Jill A.; Ottem, Randolph; Rogers, James E.; Jin, Ying; Leinwand, Steve

2011-01-01

The High School Longitudinal Study of 2009 (HSLS:09) is the fifth in a series of National Center for Education Statistics (NCES) secondary longitudinal studies. The core research questions for HSLS:09 explore secondary to postsecondary transition plans and the evolution of those plans; the paths into and out of science, technology, engineering,…

Engineering education for the 1980's: A speculation

NASA Technical Reports Server (NTRS)

Covert, E. E.

1975-01-01

The development of a course of study is briefly examined from two points of view. The first represents the background that would seem to be needed for a fledgling engineer upon his entry into the engineering profession and would allow him to complete successfully his on-the-job training, or engineering internship as it were. The second represents that which must be provided on the basis of the students background from secondary school. It is suggested that a course of study viewed in this way is never fixed, but rather evolves continuously. A particular evolving course of study is briefly discussed.

Hanford`s innovations for science education

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carter, D.

1996-12-31

In recognition of declining science literacy in the United States and a projected shortfall of scientists, engineers and technologists to address environmental problems nationally and internationally during the 21st century, Westinghouse Hanford Company has launched several innovative science education projects at the US Department of Energy Hanford Site. The Hanford Site is very rich in resources that can be brought to bear on the problem: world-class technical experts, state of the art facilities and equipment, and the largest environmental laboratory in the world. During the past two years, several innovative science education initiatives have been conceived and pursued at themore » secondary education level including the International Academy for the Environment (residential high school with an environmental theme), Environmental BATTmobile Program (mobile middle school science education program), and Multicultural Experiences in Math and Science (education program based on cultural contributions to math and science). Hanford scientists, engineers and administrators have worked with the education community (K-12 and college-university) to develop innovative approaches to science education.« less

Introduction to metabolic genetic engineering for the production of valuable secondary metabolites in in vivo and in vitro plant systems.

PubMed

Benedito, Vagner A; Modolo, Luzia V

2014-01-01

Plants are capable of producing a myriad of chemical compounds. While these compounds serve specific functions in the plant, many have surprising effects on the human body, often with positive action against diseases. These compounds are often difficult to synthesize ex vivo and require the coordinated and compartmentalized action of enzymes in living organisms. However, the amounts produced in whole plants are often small and restricted to single tissues of the plant or even cellular organelles, making their extraction an expensive process. Since most natural products used in therapeutics are specialized, secondary plant metabolites, we provide here an overview of the classification of the main classes of these compounds, with its biochemical pathways and how this information can be used to create efficient in and ex planta production pipelines to generate highly valuable compounds. Metabolic genetic engineering is introduced in light of physiological and genetic methods to enhance production of high-value plant secondary metabolites.

Electric machine for hybrid motor vehicle

DOEpatents

Hsu, John Sheungchun

2007-09-18

A power system for a motor vehicle having an internal combustion engine and an electric machine is disclosed. The electric machine has a stator, a permanent magnet rotor, an uncluttered rotor spaced from the permanent magnet rotor, and at least one secondary core assembly. The power system also has a gearing arrangement for coupling the internal combustion engine to wheels on the vehicle thereby providing a means for the electric machine to both power assist and brake in relation to the output of the internal combustion engine.

40 CFR 143.3 - Secondary maximum contaminant levels.

Code of Federal Regulations, 2013 CFR

2013-07-01

.... 143.3 Section 143.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL SECONDARY DRINKING WATER REGULATIONS § 143.3 Secondary maximum contaminant levels. The secondary maximum contaminant levels for public water systems are as follows: Contaminant...

40 CFR 143.3 - Secondary maximum contaminant levels.

Code of Federal Regulations, 2011 CFR

2011-07-01

.... 143.3 Section 143.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL SECONDARY DRINKING WATER REGULATIONS § 143.3 Secondary maximum contaminant levels. The secondary maximum contaminant levels for public water systems are as follows: Contaminant...

40 CFR 143.3 - Secondary maximum contaminant levels.

Code of Federal Regulations, 2014 CFR

2014-07-01

.... 143.3 Section 143.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL SECONDARY DRINKING WATER REGULATIONS § 143.3 Secondary maximum contaminant levels. The secondary maximum contaminant levels for public water systems are as follows: Contaminant...

40 CFR 143.3 - Secondary maximum contaminant levels.

Code of Federal Regulations, 2012 CFR

2012-07-01

.... 143.3 Section 143.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL SECONDARY DRINKING WATER REGULATIONS § 143.3 Secondary maximum contaminant levels. The secondary maximum contaminant levels for public water systems are as follows: Contaminant...

Noise and economic characteristics of an advanced blended supersonic transport concept

NASA Technical Reports Server (NTRS)

Molloy, J. K.; Grantham, W. D.; Neubauer, M. J., Jr.

1982-01-01

Noise and economic characteristics were obtained for an advanced supersonic transport concept that utilized wing body blending, a double bypass variable cycle engine, superplastically formed and diffusion bonded titanium in both the primary and secondary structures, and an alternative interior arrangement that provides increased seating capacity. The configuration has a cruise Mach number of 2.62, provisions for 290 passengers, a mission range of 8.19 Mm (4423 n.mi.), and an average operating cruise lift drag ratio of 9.23. Advanced operating procedures, which have the potential to reduce airport community noise, were explored by using a simulator. Traded jet noise levels of 105.7 and 103.4 EPNdB were obtained by using standard and advanced takeoff operational procedures, respectively. A new method for predicting lateral attenuation was utilized in obtaining these jet noise levels.

Uterine Artery Embolization: An Analysis of Online Patient Information Quality and Readability with Historical Comparison.

PubMed

Murray, Timothy E; Mansoor, Tayyaub; Bowden, Dermot J; O'Neill, Damien C; Lee, Michael J

2018-05-01

Investigators aimed to assess online information describing uterine artery embolization (UAE) to examine the quality and readability of websites patients are accessing. A list of applicable, commonly used searchable terms was generated, including "Uterine Artery Embolization," "Fibroid Embolization," "Uterine Fibroid Embolization," and "Uterine Artery Embolisation." Each possible term was assessed across the five most-used English language search engines to determine the most commonly used term. The most common term was then investigated across each search engine, with the first 25 pages returned by each engine included for analysis. Duplicate pages, nontext content such as video or audio, and pages behind paywalls were excluded. Pages were analyzed for quality and readability using validated tools including DISCERN score, JAMA Benchmark Criteria, HONcode Certification, Flesch Reading Ease Score, Flesch-Kincaid Grade Level, and Gunning-Fog Index. Secondary features such as age, rank, author, and publisher were recorded. The most common applicable term was "Uterine Artery Embolization" (492,900 results). Mean DISCERN quality of information provided by UAE websites is "fair"; however, it has declined since comparative 2012 studies. Adherence to JAMA Benchmark Criteria has reduced to 6.7%. UAE website readability remains more difficult than the World Health Organization-recommended 7-8th grade reading levels. HONcode-certified websites (35.6%) demonstrated significantly higher quality than noncertified websites. Quality of online UAE information remains "fair." Adherence to JAMA benchmark criteria is poor. Readability is above recommended 7-8th grade levels. HONcode certification was predictive of higher website quality, a useful guide to patients requesting additional information. Copyright © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Flight evaluation of an extended engine life mode on an F-15 airplane

NASA Technical Reports Server (NTRS)

Myers, Lawrence P.; Conners, Timothy R.

1992-01-01

An integrated flight and propulsion control system designed to reduce the rate of engine deterioration was developed and evaluated in flight on the NASA Dryden F-15 research aircraft. The extended engine life mode increases engine pressure ratio while reducing engine airflow to lower the turbine temperature at constant thrust. The engine pressure ratio uptrim is modulated in real time based on airplane maneuver requirements, flight conditions, and engine information. The extended engine life mode logic performed well, significantly reducing turbine operating temperature. Reductions in fan turbine inlet temperature of up to 80 F were obtained at intermediate power and up to 170 F at maximum augmented power with no appreciable loss in thrust. A secondary benefit was the considerable reduction in thrust-specific fuel consumption. The success of the extended engine life mode is one example of the advantages gained from integrating aircraft flight and propulsion control systems.

Multifaceted Learning Objective Assessment in a Mechanical Engineering Capstone Design Course

NASA Astrophysics Data System (ADS)

Baker, Nicholas S.

This thesis details multi method research approaches that have been used to study student learning objective instruction and assessment in the mechanical engineering (ME) capstone course at the University of Nevada, Reno (UNR). A primary focus of the research is to evaluate the pilot implementation of a Writing Fellows (WF) program in the ME capstone course, which has been assessed using a variety of techniques. The assessment generally indicates positive results. In particular, students favor the continuation of the program and find it more helpful than group consultations within the University Writing Center (UWC) alone. Self-assessment by the students indicates higher confidence in their communication skills, while preliminary analysis suggests that the writing fellow improved the scores of graded assignments by approximately one-third of a letter grade overall. Assessment efforts also highlight the need for deeper interaction between the WF and engineering faculty. A secondary focus of this research presents a methodology that has been developed and used to analyze how the Accreditation Board for Engineering and Technology's (ABET's) current Criterion 3 Student Outcomes (SOs) have been assessed in UNR's ME capstone class over several academic years. The methodology generally finds levels of ABET SO assessment in agreement with departmental and industry-held expectations for capstone courses at large. Finally, an analysis of student grades in the capstone course finds significant differences across semesters and identifies several potential causes.

Investigation of the spray characteristics for a secondary fuel injection nozzle using a digital image processing method

NASA Astrophysics Data System (ADS)

Jeong, Haeyoung; Lee, Kihyung; Ikeda, Yuji

2007-05-01

There are many ways to reduce diesel engine exhaust emissions. However, NOx emission is difficult to reduce because the hydrocarbon (HC) concentration in a diesel engine is not sufficient for NOx conversion. Therefore, in order to create stoichiometric conditions in the De-NOx catalyst, a secondary injection system is designed to inject liquid HC into the exhaust pipe. The atomization and distribution characteristics of the HC injected from a secondary injector are key technologies to obtain a high NOx conversion because inhomogeneous droplets of injected HC cause not only high fuel consumption but also deterioration of NOx emission. This paper describes the spray characteristics of a secondary injector including the spray angle, penetration length and breakup behaviour of the spray to optimize the reduction rate of the NOx catalyst. In this study, various optical diagnostics were applied to investigate these spray characteristics, the atomization mechanism and spray developing process. The visualization and image processing method for the spray pulsation were developed by high speed photography. The influence of the fuel supply pressure on the spray behaviour and a more detailed spray developing process have been analysed experimentally using image processing. Finally, the experimental results were used to correlate the spray structure to the injection system performance and to provide a design guide for a secondary injector nozzle.

Analysis of Coupled Seals, Secondary and Powerstream Flow Fields in Aircraft and Aerospace Turbomachines

NASA Technical Reports Server (NTRS)

Athavale, M. M.; Ho, Y. H.; Prezekwas, A. J.

2005-01-01

Higher power, high efficiency gas turbine engines require optimization of the seals and secondary flow systems as well as their impact on the powerstream. This work focuses on two aspects: 1. To apply the present day CFD tools (SCISEAL) to different real-life secondary flow applications from different original equipment manufacturers (OEM s) to provide feedback data and 2. Develop a computational methodology for coupled time-accurate simulation of the powerstream and secondary flow with emphasis on the interaction between the disk-cavity and rim seals flows with the powerstream (SCISEAL-MS-TURBO). One OEM simulation was of the Allison Engine Company T-56 turbine drum cavities including conjugate heat transfer with good agreement with data and provided design feedback information. Another was the GE aspirating seal where the 3-D CFD simulations played a major role in analysis and modification of that seal configuration. The second major objective, development of a coupled flow simulation capability was achieved by using two codes MS-TURBO for the powerstream and SCISEAL for the secondary flows with an interface coupling algorithm. The coupled code was tested against data from three differed configurations: 1. bladeless-rotor-stator-cavity turbine test rig, 2. UTRC high pressure turbine test rig, and, 3. the NASA Low-Speed-Air Compressor rig (LSAC) with results and limitations discussed herein.

Biosynthetic approaches to creating bioactive fungal metabolites: Pathway engineering and activation of secondary metabolism.

PubMed

Motoyama, Takayuki; Osada, Hiroyuki

2016-12-15

The diversity of natural products is greater than that of combinatorial chemistry compounds and is similar to that of drugs. Compounds rich in sp 3 carbons, such as natural products, typically exhibit high structural complexity and high specificity to molecular targets. Microorganisms can synthesize such sp 3 carbon-rich compounds and can be used as excellent factories for making bioactive compounds. Here, we mainly focus on pathway engineering of two sp 3 carbon-rich bioactive indole alkaloids, fumitremorgin C and terpendole E. We also demonstrate the importance of activation of secondary metabolism by focusing on tenuazonic acid, a bioactive tetramic acid compound, as an example. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimal Micro-Jet Flow Control for Compact Air Vehicle Inlets

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.; Miller, Daniel N.; Addington, Gregory A.; Agrell, Johan

2004-01-01

The purpose of this study on micro-jet secondary flow control is to demonstrate the viability and economy of Response Surface Methodology (RSM) to optimally design micro-jet secondary flow control arrays, and to establish that the aeromechanical effects of engine face distortion can also be included in the design and optimization process. These statistical design concepts were used to investigate the design characteristics of "low mass" micro-jet array designs. The term "low mass" micro-jet may refers to fluidic jets with total (integrated) mass flow ratios between 0.10 and 1.0 percent of the engine face mass flow. Therefore, this report examines optimal micro-jet array designs for compact inlets through a Response Surface Methodology.

Volatile science? Metabolic engineering of terpenoids in plants.

PubMed

Aharoni, Asaph; Jongsma, Maarten A; Bouwmeester, Harro J

2005-12-01

Terpenoids are important for plant survival and also possess biological properties that are beneficial to humans. Here, we describe the state of the art in terpenoid metabolic engineering, showing that significant progress has been made over the past few years. Subcellular targeting of enzymes has demonstrated that terpenoid precursors in subcellular compartments are not as strictly separated as previously thought and that multistep pathway engineering is feasible, even across cell compartments. These engineered plants show that insect behavior is influenced by terpenoids. In the future, we expect rapid progress in the engineering of terpenoid production in plants. In addition to commercial applications, such transgenic plants should increase our understanding of the biological relevance of these volatile secondary metabolites.

2007 NASA Seal/Secondary Air System Workshop. Volume 1

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Hendricks, Robert C.; Delgado, Irebert

2008-01-01

The 2007 NASA Seal/Secondary Air System workshop covered the following topics: (i) Overview of NASA's new Orion project aimed at developing a new spacecraft that will fare astronauts to the International Space Station, the Moon, Mars, and beyond; (ii) Overview of NASA's fundamental aeronautics technology project; (iii) Overview of NASA Glenn s seal project aimed at developing advanced seals for NASA's turbomachinery, space, and reentry vehicle needs; (iv) Reviews of NASA prime contractor, vendor, and university advanced sealing concepts, test results, experimental facilities, and numerical predictions; and (v) Reviews of material development programs relevant to advanced seals development. Turbine engine studies have shown that reducing seal leakage as well as high-pressure turbine (HPT) blade tip clearances will reduce fuel burn, lower emissions, retain exhaust gas temperature margin, and increase range. Turbine seal development topics covered include a method for fast-acting HPT blade tip clearance control, noncontacting low-leakage seals, intershaft seals, and a review of engine seal performance requirements for current and future Army engine platforms.

2008 NASA Seal/Secondary Air System Workshop

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M. (Editor); Hendricks, Robert C. (Editor); Delgado, Irebert R. (Editor)

2009-01-01

The 2008 NASA Seal/Secondary Air System Workshop covered the following topics: (i) Overview of NASA s new Orion project aimed at developing a new spacecraft that will fare astronauts to the International Space Station, the Moon, Mars, and beyond; (ii) Overview of NASA s fundamental aeronautics technology project; (iii) Overview of NASA Glenn s seal project aimed at developing advanced seals for NASA s turbomachinery, space, and reentry vehicle needs; (iv) Reviews of NASA prime contractor, vendor, and university advanced sealing concepts, test results, experimental facilities, and numerical predictions; and (v) Reviews of material development programs relevant to advanced seals development. Turbine engine studies have shown that reducing seal leakage as well as high-pressure turbine (HPT) blade tip clearances will reduce fuel burn, lower emissions, retain exhaust gas temperature margin, and increase range. Turbine seal development topics covered include a method for fast-acting HPT blade tip clearance control, noncontacting low-leakage seals, intershaft seals, and a review of engine seal performance requirements for current and future Army engine platforms.

Process and apparatus for afterburning of combustible pollutants from an internal combustion engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laurent, P.A.

1978-07-04

In a process for the afterburning of the combustible pollutants from an internal combustion engine, in order to automatically reduce the secondary induction rate when power increases without using a controlling valve actuatd by the carburetor venturi depression, there is provided a volumetric efficiency of the secondary air pump linked to and activated by the engine and a volumetric efficiency which decreases when the ratio between its back pressure and suction pressure increases, this reduction being achieved through the proper selection of the pump volumetric compression ratio r: between 0.6 c and 1.3 c when a steeply decreasing trend ismore » required, and above 1.3 c if a slower and slower decreasing trend is required. To perform this process an afterburner apparatus has a nitrogen oxide reducing catalyst placed inside the afterburner reactor on the gas stream immediately at the outlet of a torus, in which the gases are homogenized and their reaction with preinjection air is terminated.« less

Optimization of Dish Solar Collectors with and without Secondary Concentrators

NASA Technical Reports Server (NTRS)

Jaffe, L. D.

1982-01-01

Methods for optimizing parabolic dish solar collectors and the consequent effects of various optical, thermal, mechanical, and cost variables are examined. The most important performance optimization is adjusting the receiver aperture to maximize collector efficiency. Other parameters that can be adjusted to optimize efficiency include focal length, and, if a heat engine is used, the receiver temperature. The efficiency maxima associated with focal length and receiver temperature are relatively broad; it may, accordingly, be desirable to design somewhat away from the maxima. Performance optimization is sensitive to the slope and specularity errors of the concentrator. Other optical and thermal variables affecting optimization are the reflectance and blocking factor of the concentrator, the absorptance and losses of the receiver, and, if a heat engine is used, the shape of the engine efficiency versus temperature curve. Performance may sometimes be improved by use of an additional optical element (a secondary concentrator) or a receiver window if the errors of the primary concentrator are large or the receiver temperature is high.

Development and validation of science, technology, engineering and mathematics (STEM) based instructional material

NASA Astrophysics Data System (ADS)

Gustiani, Ineu; Widodo, Ari; Suwarma, Irma Rahma

2017-05-01

This study is intended to examine the development and validation of simple machines instructional material that developed based on Science, Technology, Engineering and Mathematics (STEM) framework that provides guidance to help students learn and practice for real life and enable individuals to use knowledge and skills they need to be an informed citizen. Sample of this study consist of one class of 8th grader at a junior secondary school in Bandung, Indonesia. To measure student learning, a pre-test and post-test were given before and after implementation of the STEM based instructional material. In addition, a questionnaire of readability was given to examine the clarity and difficulty level of each page of instructional material. A questionnaire of students' response towards instructional material given to students and teachers at the end of instructional material reading session to measure layout aspects, content aspects and utility aspects of instructional material for being used in the junior secondary school classroom setting. The results show that readability aspect and students' response towards STEM based instructional material of STEM based instructional material is categorized as very high. Pretest and posttest responses revealed that students retained significant amounts information upon completion of the STEM instructional material. Student overall learning gain is 0.67 which is categorized as moderate. In summary, STEM based instructional material that was developed is valid enough to be used as educational materials necessary for conducting effective STEM education.

Generation and characterization of gasoline engine exhaust inhalation exposure atmospheres.

PubMed

McDonald, Jacob D; Barr, Edward B; White, Richard K; Kracko, Dean; Chow, Judith C; Zielinska, Barbara; Grosjean, Eric

2008-10-01

Exposure atmospheres for a rodent inhalation toxicology study were generated from the exhaust of a 4.3-L gasoline engine coupled to a dynamometer and operated on an adapted California Unified Driving Cycle. Exposure levels were maintained at three different dilution rates. One chamber at the lowest dilution had particles removed by filtration. Each exposure atmosphere was characterized for particle mass, particle number, particle size distribution, and detailed chemical speciation. The majority of the mass in the exposure atmospheres was gaseous carbon monoxide, nitrogen oxides, and volatile organics, with small amounts of particle-bound carbon/ions and metals. The atmospheres varied according to the cycle, with the largest spikes in volatile organic and inorganic species shown during the "cold start" portion of the cycle. Ammonia present from the exhaust and rodents interacted with the gasoline exhaust to form secondary inorganic particles, and an increase in exhaust resulted in higher proportions of secondary inorganics as a portion of the total particle mass. Particle size had a median of 10-20 nm by number and approximately 150 nm by mass. Volatile organics matched the composition of the fuel, with large proportions of aliphatic and aromatic hydrocarbons coupled to low amounts of oxygenated organics. A new measurement technique revealed organics reacting with nitrogen oxides have likely resulted in measurement bias in previous studies of combustion emissions. Identified and measured particle organic species accounted for about 10% of total organic particle mass and were mostly aliphatic acids and polycyclic aromatic hydrocarbons.

Biotechnological production of pharmaceuticals and biopharmaceuticals in plant cell and organ cultures.

PubMed

Hidalgo, Diego; Sanchez, Raul; Lalaleo, Liliana; Bonfill, Mercedes; Corchete, Purificacion; Palazon, Javier

2018-03-09

Plant biofactories are biotechnological platforms based on plant cell and organ cultures used for the production of pharmaceuticals and biopharmaceuticals, although to date only a few of these systems have successfully been implemented at an industrial level. Metabolic engineering is possibly the most straightforward strategy to boost pharmaceutical production in plant biofactories, but social opposition to the use of GMOs means empirical approaches are still being used. Plant secondary metabolism involves thousands of different enzymes, some of which catalyze specific reactions, giving one product from a particular substrate, whereas others can yield multiple products from the same substrate. This trait opens plant cell biofactories to new applications, in which the natural metabolic machinery of plants can be harnessed for the bioconversion of phytochemicals or even the production of new bioactive compounds. Synthetic biological pipelines involving the bioconversion of natural substrates into products with a high market value may be established by the heterologous expression of target metabolic genes in model plants. To summarize the state of the art of plant biofactories and their applications for the pipeline production of cosme-, pharma- and biopharmaceuticals. In order to demonstrate the great potential of plant biofactories for multiple applications in the biotechnological production of pharmaceuticals and biopharmaceuticals, this review broadly covers the following: plant biofactories based on cell and hairy root cultures; secondary metabolite production; biotransformation reactions; metabolic engineering tools applied in plant biofactories; and biopharmaceutical production. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Designing Worked Examples in Statics to Promote an Expert Stance: Working THRU vs. Working OUT

ERIC Educational Resources Information Center

Calfee, Robert; Stahovich, Thomas

2011-01-01

The purpose of this study was to examine the performance patterns of freshman engineering students as they completed a tutorial on freebody problems that employed a computer-based pen (CBP) to provide feedback and direct learning. A secondary analysis was conducted on detailed performance data for 16 participants from a freshman Engineering course…

Integration of iPad-Based M-Learning into a Creative Engineering Module in a Secondary School in England

ERIC Educational Resources Information Center

Li, Yulong; Liu, Xiaojing

2017-01-01

Mobile learning (M-learning) has become a popular topic in educational research, in previous research there have been many studies on attitude to M-learning directed towards staff, parents and students; however, limited research has focused on the comparison between teachers and students in the context of creative engineering and their respective…

Fretting in aircraft turbine engines

NASA Technical Reports Server (NTRS)

Johnson, R. L.; Bill, R. C.

1974-01-01

The problem of fretting in aircraft turbine engines is discussed. Critical fretting can occur on fan, compressor, and turbine blade mountings, as well as on splines, rolling element bearing races, and secondary sealing elements of face type seals. Structural fatigue failures have been shown to occur at fretted areas on component parts. Methods used by designers to reduce the effects of fretting are given.

Program Guide for Diesel Engine Mechanics 8742000 (IN47.060500) and Heavy Duty Truck and Bus Mechanics DIM0991 (IN47.060501).

ERIC Educational Resources Information Center

University of South Florida, Tampa. Coll. of Education.

This competency-based program guide provides course content information and procedures for secondary schools, postsecondary vocational schools, and community colleges in Florida that conduct programs in diesel engine mechanics and heavy duty truck and bus mechanics. The first section is on legal authority, which applies to all vocational education…

Affordable Rankine Cycle Waste Heat Recovery for Heavy Duty Trucks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subramanian, Swami Nathan

Nearly 30% of fuel energy is not utilized and wasted in the engine exhaust. Organic Rankine Cycle (ORC) based waste heat recovery (WHR) systems offer a promising approach on waste energy recovery and improving the efficiency of Heavy-Duty diesel engines. Major barriers in the ORC WHR system are the system cost and controversial waste heat recovery working fluids. More than 40% of the system cost is from the additional heat exchangers (recuperator, condenser and tail pipe boiler). The secondary working fluid loop designed in ORC system is either flammable or environmentally sensitive. The Eaton team investigated a novel approach tomore » reduce the cost of implementing ORC based WHR systems to Heavy-Duty (HD) Diesel engines while utilizing safest working fluids. Affordable Rankine Cycle (ARC) concept aimed to define the next generation of waste energy recuperation with a cost optimized WHR system. ARC project used engine coolant as the working fluid. This approach reduced the need for a secondary working fluid circuit and subsequent complexity. A portion of the liquid phase engine coolant has been pressurized through a set of working fluid pumps and used to recover waste heat from the exhaust gas recirculation (EGR) and exhaust tail pipe exhaust energy. While absorbing heat, the mixture is partially vaporized but remains a wet binary mixture. The pressurized mixed-phase engine coolant mixture is then expanded through a fixed-volume ratio expander that is compatible with two-phase conditions. Heat rejection is accomplished through the engine radiator, avoiding the need for a separate condenser. The ARC system has been investigated for PACCAR’s MX-13 HD diesel engine.« less

Structural characterization of the α-mating factor prepro-peptide for secretion of recombinant proteins in Pichia pastoris.

PubMed

Chahal, Sabreen; Wei, Peter; Moua, Pachai; Park, Sung Pil James; Kwon, Janet; Patel, Arth; Vu, Anthony T; Catolico, Jason A; Tsai, Yu Fang Tina; Shaheen, Nadia; Chu, Tiffany T; Tam, Vivian; Khan, Zill-E-Huma; Joo, Hyun Henry; Xue, Liang; Lin-Cereghino, Joan; Tsai, Jerry W; Lin-Cereghino, Geoff P

2017-01-20

The methylotrophic yeast Pichia pastoris has been used extensively for expressing recombinant proteins because it combines the ease of genetic manipulation, the ability to provide complex posttranslational modifications and the capacity for efficient protein secretion. The most successful and commonly used secretion signal leader in Pichia pastoris has been the alpha mating factor (MATα) prepro secretion signal. However, limitations exist as some proteins cannot be secreted efficiently, leading to strategies to enhance secretion efficiency by modifying the secretion signal leader. Based on a Jpred secondary structure prediction and knob-socket modeling of tertiary structure, numerous deletions and duplications of the MATα prepro leader were engineered to evaluate the correlation between predicted secondary structure and the secretion level of the reporters horseradish peroxidase (HRP) and Candida antarctica lipase B. In addition, circular dichroism analyses were completed for the wild type and several mutant pro-peptides to evaluate actual differences in secondary structure. The results lead to a new model of MATα pro-peptide signal leader, which suggests that the N and C-termini of MATα pro-peptide need to be presented in a specific orientation for proper interaction with the cellular secretion machinery and for efficient protein secretion. Copyright © 2016 Elsevier B.V. All rights reserved.

Engineering Plant One-Carbon Metabolism

DOE Office of Scientific and Technical Information (OSTI.GOV)

David Rhodes

2005-02-09

Primary and secondary metabolism intersect in the one-carbon (C1) area. Primary metabolism supplies most of the C1 units and competes with secondary metabolism for their use. This competition is potentially severe because secondary products such as lignin, alkaloids, and glycine betaine (GlyBet) require massive amounts of C1 units. Towards the goal of understanding how C1 metabolism is regulated at the metabolic and gene levels so as to successfully engineer C1 supply to match demand, we have: (1) cloned complete suites of C1 genes from maize and tobacco, and incorporated them into DNA arrays; (2) prepared antisense constructs and mutants engineeredmore » with alterations in C1 unit supply and demand; and (3) have quantified the impacts of these alterations on gene expression (using DNA arrays), and on metabolic fluxes (by combining isotope labeling, MS, NMR and computer modeling). Metabolic flux analysis and modeling in tobacco engineered for GlyBet synthesis by expressing choline oxidizing enzymes in either the chloroplast or cytosol, has shown that the choline biosynthesis network is rigid, and tends to resist large changes in C1 demand. A major constraint on engineering enhanced flux to GlyBet in tobacco is a low capacity of choline transport across the chloroplast envelope. Maize and sorghum mutants defective in GlyBet synthesis show greatly reduced flux of C1 units into choline in comparison to GlyBet-accumulating wildtypes, but this is not associated with altered expression of any of the C1 genes. Control of C1 flux to choline in tobacco, maize and sorghum appears to reside primarily at the level of N-methylation of phosphoethanolamine. A candidate signal for the control of this flux is the pool size of phosphocholine which down-regulates and feedback inhibits phosphoethanolamine N-methyltransferase. Methionine S-methyltransferase (MMT) catalyzes the synthesis of S-methylmethionine (SMM) from methionine (Met) and S-adenosylmethionine (AdoMet). SMM can be reconverted to Met by donating a methyl group to homocysteine, and concurrent operation of this reaction and that mediated by MMT sets up the SMM cycle. The genes encoding the enzymes of the SMM cycle were cloned and characterized during this project. SMM has been hypothesized to be essential as a methyl donor or as a transport form of sulfur, and the SMM cycle has been hypothesized to guard against depletion of the free Met pool by excess AdoMet synthesis, or to regulate AdoMet level and hence the AdoMet/S-adenosylhomocysteine ratio (the methylation ratio). To test these hypotheses, we isolated insertional mmt mutants of Arabidopsis and maize. Both mutants lacked the capacity to produce SMM and thus had no SMM cycle. They nevertheless grew and reproduced normally and the seeds of the Arabidopsis mutant had normal sulfur contents. These findings rule out an indispensable role for SMM as a methyl donor or in sulfur transport. The Arabidopsis mutant had significantly higher AdoMet a nd lower S-adenosylhomocysteine (AdoHCy) levels than the wild type, and consequently a higher methylation ratio (20 vs. 14). Free Met and thiol pools were unaltered in this mutant, although there was a 50% decrease in free threonine (Thr) and changes in other amino acids. These data indicate that the SMM cycle contributes to regulation of AdoMet levels rather than preventing depletion of free Met. Since AdoMet activates Thr synthase, that Thr level was not higher but lower in the mmt mutant implies that AdoMet is sequestered away from Thr synthase, which is chloroplastic. Results obtained with the Arabidopsis mmt mutant and wildtype have been integrated into a metabolic model of the intersecting methylation, SMM, and methionine salvage cycles. This model adequately accounts for the steady-state pool sizes of Met, SMM, AdoMet and AdoHCy in wildtype, and the small changes in AdoMet and AdoHCy levels associated with knockout of MMT. This model is now being used to predict the time-course of changes in AdoMet, Met, AdoHCy, and SMM mass isotopomers when Arabidopsis is fed with 13C5-Met at different doses, and to evaluate the metabolic consequences of knockout of adenosine kinase or AdoHCy hydrolase in Arabidopsis.« less

Application of the Andersen's health care utilization framework to secondary complications of spinal cord injury: a scoping review.

PubMed

Guilcher, Sara J T; Craven, B Cathy; McColl, Mary Ann; Lemieux-Charles, Louise; Casciaro, Tiziana; Jaglal, Susan B

2012-01-01

The purpose of this scoping review was to identify research priority areas related to secondary complications and associated health care use for individuals with spinal cord injury (SCI). Peer-reviewed journals were identified using CINAHL, MEDLINE, PubMed, Embase, Social Sciences Abstracts, Social Works Abstract and PsycInfo search engines. Key references were hand searched. A total of 289 abstracts were identified from the initial search strategy. We removed studies that did not measure health care and those that did not involve analytical investigation. The selected 31 studies were reviewed in detail using a coding template based on the domains and sub-components of the Andersen model (i.e. environmental, population characteristics, health behavior and outcome). Most studies measured predisposing characteristics (e.g., age, gender) and need characteristics (e.g., level of injury). There was a notable absence of environmental characteristics (e.g., health system, neighborhood variables), enabling characteristics and health behaviors (beyond diet and nutrition). We identified a gap in the SCI literature. Future research should focus on longitudinal study designs with more representation of non-traumatic spinal cord injury, as well as utilizing more advanced statistical analyses (i.e., multivariate level) to adjust for confounding variables.

Who Is Teaching Science in Our High Schools? Exploring Factors Influencing Pre-Service Secondary Science Teachers' Decisions to Pursue Teaching as a Career

ERIC Educational Resources Information Center

McDonald, Christine V.

2017-01-01

A central objective of recent government reports focused on the important role of education in preparing a skilled and dynamic science, technology, engineering and mathematics (STEM) workforce, with effective teaching in secondary STEM classrooms reliant on the engagement and retention of high-quality STEM teachers (Office of the Chief Scientist,…

Prevalence, Gender and Level of Schooling Differences in Secondary School Students Level of Shyness

ERIC Educational Resources Information Center

Onukwufor, Jonathan N.; Iruloh, Betty-Ruth Ngozi

2017-01-01

This study was conducted to ascertain the prevalence, gender and level of schooling differences in secondary school students' level of shyness in Ikwerre Local Government Area of Rivers State. Population of the study comprised all the senior secondary school class two (SSS II) and all the Junior Secondary school class two (JSS II) students in the…

Citrate-Coated Silver Nanoparticles Growth-Independently Inhibit Aflatoxin Synthesis in Aspergillus parasiticus.

PubMed

Mitra, Chandrani; Gummadidala, Phani M; Afshinnia, Kamelia; Merrifield, Ruth C; Baalousha, Mohammed; Lead, Jamie R; Chanda, Anindya

2017-07-18

Manufactured silver nanoparticles (Ag NPs) have long been used as antimicrobials. However, little is known about how these NPs affect fungal cell functions. While multiple previous studies reveal that Ag NPs inhibit secondary metabolite syntheses in several mycotoxin producing filamentous fungi, these effects are associated with growth repression and hence need sublethal to lethal NP doses, which besides stopping fungal growth, can potentially accumulate in the environment. Here we demonstrate that citrate-coated Ag NPs of size 20 nm, when applied at a selected nonlethal dose, can result in a >2 fold inhibition of biosynthesis of the carcinogenic mycotoxin and secondary metabolite, aflatoxin B 1 in the filamentous fungus and an important plant pathogen, Aspergillus parasiticus, without inhibiting fungal growth. We also show that the observed inhibition was not due to Ag ions, but was specifically associated with the mycelial uptake of Ag NPs. The NP exposure resulted in a significant decrease in transcript levels of five aflatoxin genes and at least two key global regulators of secondary metabolism, laeA and veA, with a concomitant reduction of total reactive oxygen species (ROS). Finally, the depletion of Ag NPs in the growth medium allowed the fungus to regain completely its ability of aflatoxin biosynthesis. Our results therefore demonstrate the feasibility of Ag NPs to inhibit fungal secondary metabolism at nonlethal concentrations, hence providing a novel starting point for discovery of custom designed engineered nanoparticles that can efficiently prevent mycotoxins with minimal risk to health and environment.

Achieving Sex Equity in Education: A Comparison at Pre- and Post-Secondary Levels.

ERIC Educational Resources Information Center

Klein, Susan S.; Bogart, Karen

1987-01-01

Describes how sex inequities found at the elementary and secondary levels resemble or differ from those at the post-secondary level. Identifies strategies to promote equity that can be used at each level. (PS)

ON THE PROBLEM OF CORRECTING TWISTED TURBINE BLADES,

DTIC Science & Technology

TURBINE BLADES , DESIGN), GAS TURBINES , STEAM TURBINES , BLADE AIRFOILS , ASPECT RATIO, FLUID DYNAMICS, SECONDARY FLOW, ANGLE OF ATTACK, INLET GUIDE VANES , CORRECTIONS, PERFORMANCE( ENGINEERING ), OPTIMIZATION, USSR

Encouraging more women into computer science: Initiating a single-sex intervention program in Sweden

NASA Astrophysics Data System (ADS)

Brandell, Gerd; Carlsson, Svante; Ekblom, Håkan; Nord, Ann-Charlotte

1997-11-01

The process of starting a new program in computer science and engineering, heavily based on applied mathematics and only open to women, is described in this paper. The program was introduced into an educational system without any tradition in single-sex education. Important observations made during the process included the considerable interest in mathematics and curiosity about computer science found among female students at the secondary school level, and the acceptance of the single-sex program by the staff, administration, and management of the university as well as among male and female students. The process described highlights the importance of preparing the environment for a totally new type of educational program.

Steps towards the synthetic biology of polyketide biosynthesis.

PubMed

Cummings, Matthew; Breitling, Rainer; Takano, Eriko

2014-02-01

Nature is providing a bountiful pool of valuable secondary metabolites, many of which possess therapeutic properties. However, the discovery of new bioactive secondary metabolites is slowing down, at a time when the rise of multidrug-resistant pathogens and the realization of acute and long-term side effects of widely used drugs lead to an urgent need for new therapeutic agents. Approaches such as synthetic biology are promising to deliver a much-needed boost to secondary metabolite drug development through plug-and-play optimized hosts and refactoring novel or cryptic bacterial gene clusters. Here, we discuss this prospect focusing on one comprehensively studied class of clinically relevant bioactive molecules, the polyketides. Extensive efforts towards optimization and derivatization of compounds via combinatorial biosynthesis and classical engineering have elucidated the modularity, flexibility and promiscuity of polyketide biosynthetic enzymes. Hence, a synthetic biology approach can build upon a solid basis of guidelines and principles, while providing a new perspective towards the discovery and generation of novel and new-to-nature compounds. We discuss the lessons learned from the classical engineering of polyketide synthases and indicate their importance when attempting to engineer biosynthetic pathways using synthetic biology approaches for the introduction of novelty and overexpression of products in a controllable manner. © 2013 The Authors FEMS Microbiology Letters published by John Wiley & Sons Ltd on behalf of Federation of European Microbiological Societies.

THRSTER: A THRee-STream Ejector Ramjet Analysis and Design Tool

NASA Technical Reports Server (NTRS)

Chue, R. S.; Sabean, J.; Tyll, J.; Bakos, R. J.

2000-01-01

An engineering tool for analyzing ejectors in rocket based combined cycle (RBCC) engines has been developed. A key technology for multi-cycle RBCC propulsion systems is the ejector which functions as the compression stage of the ejector ramjet cycle. The THRee STream Ejector Ramjet analysis tool was developed to analyze the complex aerothermodynamic and combustion processes that occur in this device. The formulated model consists of three quasi-one-dimensional streams, one each for the ejector primary flow, the secondary flow, and the mixed region. The model space marches through the mixer, combustor, and nozzle to evaluate the solution along the engine. In its present form, the model is intended for an analysis mode in which the diffusion rates of the primary and secondary into the mixed stream are stipulated. The model offers the ability to analyze the highly two-dimensional ejector flowfield while still benefits from the simplicity and speed of an engineering tool. To validate the developed code, wall static pressure measurements from the Penn-State and NASA-ART RBCC experiments were used to compare with the results generated by the code. The calculated solutions were generally found to have satisfactory agreement with the pressure measurements along the engines, although further modeling effort may be required when a strong shock train is formed at the rocket exhaust. The range of parameters in which the code would generate valid results are presented and discussed.

THRSTER: A Three-Stream Ejector Ramjet Analysis and Design Tool

NASA Technical Reports Server (NTRS)

Chue, R. S.; Sabean, J.; Tyll, J.; Bakos, R. J.; Komar, D. R. (Technical Monitor)

2000-01-01

An engineering tool for analyzing ejectors in rocket based combined cycle (RBCC) engines has been developed. A key technology for multi-cycle RBCC propulsion systems is the ejector which functions as the compression stage of the ejector ramjet cycle. The THRee STream Ejector Ramjet analysis tool was developed to analyze the complex aerothermodynamic and combustion processes that occur in this device. The formulated model consists of three quasi-one-dimensional streams, one each for the ejector primary flow, the secondary flow, and the mixed region. The model space marches through the mixer, combustor, and nozzle to evaluate the solution along the engine. In its present form, the model is intended for an analysis mode in which the diffusion rates of the primary and secondary into the mixed stream are stipulated. The model offers the ability to analyze the highly two-dimensional ejector flowfield while still benefits from the simplicity and speed of an engineering tool. To validate the developed code, wall static pressure measurements from the Penn-State and NASA-ART RBCC experiments were used to compare with the results generated by the code. The calculated solutions were generally found to have satisfactory agreement with the pressure measurements along the engines, although further modeling effort may be required when a strong shock train is formed at the rocket exhaust. The range of parameters in which the code would generate valid results are presented and discussed.

Investigating Diesel Engines as an Atmospheric Source of Isocyanic Acid in Urban Areas

NASA Astrophysics Data System (ADS)

Farmer, D.; Jathar, S.; Heppding, C.; Link, M.; Akherati, A.; Kleeman, M.; De Gouw, J. A.; Veres, P. R.; Roberts, J. M.

2017-12-01

Isocyanic acid (HNCO), an acidic gas found in tobacco smoke, urban environments and biomass burning-affected regions, has been linked to adverse health outcomes. Gasoline- and diesel-powered engines and biomass burning are known to emit HNCO and hypothesized to emit precursors such as amides that can photochemically react to produce HNCO in the atmosphere. Increasingly, diesel engines in developed countries like the United States are required to use Selective Catalytic Reduction (SCR) systems to reduce tailpipe emissions of oxides of nitrogen. SCR chemistry is known to produce HNCO as an intermediate product, and SCR systems have been implicated as an atmospheric source of HNCO. In this work, we measure HNCO emissions from an SCR system-equipped diesel engine and, in combination with earlier data, use a three-dimensional chemical transport model (CTM) to simulate the ambient concentrations and source/pathway contributions to HNCO in an urban environment. Engine tests were conducted at three different engine loads, using two different fuels and at multiple operating points. HNCO was measured using an acetate chemical ionization mass spectrometer. The diesel engine was found to emit primary HNCO (3-90 mg kg-fuel-1) but we did not find any evidence that the SCR system or other aftertreatment devices (i.e., oxidation catalyst and particle filter) produced or enhanced HNCO emissions. The CTM predictions compared well with the only available observational data sets for HNCO in urban areas but under-predicted the contribution from secondary processes. The comparison implied that diesel-powered engines were the largest source of HNCO in urban areas. The CTM also predicted that daily-averaged concentrations of HNCO reached a maximum of 110 pptv but were an order of magnitude lower than the 1 ppbv level that could be associated with physiological effects in humans. Precursor contributions from other combustion sources (gasoline and biomass burning) and wintertime conditions could enhance HNCO concentrations but need to be explored in future work.

Investigating diesel engines as an atmospheric source of isocyanic acid in urban areas

NASA Astrophysics Data System (ADS)

Jathar, Shantanu H.; Heppding, Christopher; Link, Michael F.; Farmer, Delphine K.; Akherati, Ali; Kleeman, Michael J.; de Gouw, Joost A.; Veres, Patrick R.; Roberts, James M.

2017-07-01

Isocyanic acid (HNCO), an acidic gas found in tobacco smoke, urban environments, and biomass-burning-affected regions, has been linked to adverse health outcomes. Gasoline- and diesel-powered engines and biomass burning are known to emit HNCO and hypothesized to emit precursors such as amides that can photochemically react to produce HNCO in the atmosphere. Increasingly, diesel engines in developed countries like the United States are required to use selective catalytic reduction (SCR) systems to reduce tailpipe emissions of oxides of nitrogen. SCR chemistry is known to produce HNCO as an intermediate product, and SCR systems have been implicated as an atmospheric source of HNCO. In this work, we measure HNCO emissions from an SCR system-equipped diesel engine and, in combination with earlier data, use a three-dimensional chemical transport model (CTM) to simulate the ambient concentrations and source/pathway contributions to HNCO in an urban environment. Engine tests were conducted at three different engine loads, using two different fuels and at multiple operating points. HNCO was measured using an acetate chemical ionization mass spectrometer. The diesel engine was found to emit primary HNCO (3-90 mg kg fuel-1) but we did not find any evidence that the SCR system or other aftertreatment devices (i.e., oxidation catalyst and particle filter) produced or enhanced HNCO emissions. The CTM predictions compared well with the only available observational datasets for HNCO in urban areas but underpredicted the contribution from secondary processes. The comparison implied that diesel-powered engines were the largest source of HNCO in urban areas. The CTM also predicted that daily-averaged concentrations of HNCO reached a maximum of ˜ 110 pptv but were an order of magnitude lower than the 1 ppbv level that could be associated with physiological effects in humans. Precursor contributions from other combustion sources (gasoline and biomass burning) and wintertime conditions could enhance HNCO concentrations but need to be explored in future work.

RNA FRABASE 2.0: an advanced web-accessible database with the capacity to search the three-dimensional fragments within RNA structures

PubMed Central

2010-01-01

Background Recent discoveries concerning novel functions of RNA, such as RNA interference, have contributed towards the growing importance of the field. In this respect, a deeper knowledge of complex three-dimensional RNA structures is essential to understand their new biological functions. A number of bioinformatic tools have been proposed to explore two major structural databases (PDB, NDB) in order to analyze various aspects of RNA tertiary structures. One of these tools is RNA FRABASE 1.0, the first web-accessible database with an engine for automatic search of 3D fragments within PDB-derived RNA structures. This search is based upon the user-defined RNA secondary structure pattern. In this paper, we present and discuss RNA FRABASE 2.0. This second version of the system represents a major extension of this tool in terms of providing new data and a wide spectrum of novel functionalities. An intuitionally operated web server platform enables very fast user-tailored search of three-dimensional RNA fragments, their multi-parameter conformational analysis and visualization. Description RNA FRABASE 2.0 has stored information on 1565 PDB-deposited RNA structures, including all NMR models. The RNA FRABASE 2.0 search engine algorithms operate on the database of the RNA sequences and the new library of RNA secondary structures, coded in the dot-bracket format extended to hold multi-stranded structures and to cover residues whose coordinates are missing in the PDB files. The library of RNA secondary structures (and their graphics) is made available. A high level of efficiency of the 3D search has been achieved by introducing novel tools to formulate advanced searching patterns and to screen highly populated tertiary structure elements. RNA FRABASE 2.0 also stores data and conformational parameters in order to provide "on the spot" structural filters to explore the three-dimensional RNA structures. An instant visualization of the 3D RNA structures is provided. RNA FRABASE 2.0 is freely available at http://rnafrabase.cs.put.poznan.pl. Conclusions RNA FRABASE 2.0 provides a novel database and powerful search engine which is equipped with new data and functionalities that are unavailable elsewhere. Our intention is that this advanced version of the RNA FRABASE will be of interest to all researchers working in the RNA field. PMID:20459631

RNA FRABASE 2.0: an advanced web-accessible database with the capacity to search the three-dimensional fragments within RNA structures.

PubMed

Popenda, Mariusz; Szachniuk, Marta; Blazewicz, Marek; Wasik, Szymon; Burke, Edmund K; Blazewicz, Jacek; Adamiak, Ryszard W

2010-05-06

Recent discoveries concerning novel functions of RNA, such as RNA interference, have contributed towards the growing importance of the field. In this respect, a deeper knowledge of complex three-dimensional RNA structures is essential to understand their new biological functions. A number of bioinformatic tools have been proposed to explore two major structural databases (PDB, NDB) in order to analyze various aspects of RNA tertiary structures. One of these tools is RNA FRABASE 1.0, the first web-accessible database with an engine for automatic search of 3D fragments within PDB-derived RNA structures. This search is based upon the user-defined RNA secondary structure pattern. In this paper, we present and discuss RNA FRABASE 2.0. This second version of the system represents a major extension of this tool in terms of providing new data and a wide spectrum of novel functionalities. An intuitionally operated web server platform enables very fast user-tailored search of three-dimensional RNA fragments, their multi-parameter conformational analysis and visualization. RNA FRABASE 2.0 has stored information on 1565 PDB-deposited RNA structures, including all NMR models. The RNA FRABASE 2.0 search engine algorithms operate on the database of the RNA sequences and the new library of RNA secondary structures, coded in the dot-bracket format extended to hold multi-stranded structures and to cover residues whose coordinates are missing in the PDB files. The library of RNA secondary structures (and their graphics) is made available. A high level of efficiency of the 3D search has been achieved by introducing novel tools to formulate advanced searching patterns and to screen highly populated tertiary structure elements. RNA FRABASE 2.0 also stores data and conformational parameters in order to provide "on the spot" structural filters to explore the three-dimensional RNA structures. An instant visualization of the 3D RNA structures is provided. RNA FRABASE 2.0 is freely available at http://rnafrabase.cs.put.poznan.pl. RNA FRABASE 2.0 provides a novel database and powerful search engine which is equipped with new data and functionalities that are unavailable elsewhere. Our intention is that this advanced version of the RNA FRABASE will be of interest to all researchers working in the RNA field.

Effects of Diesel Engine Exhaust Origin Secondary Organic Aerosols on Novel Object Recognition Ability and Maternal Behavior in BALB/C Mice

PubMed Central

Win-Shwe, Tin-Tin; Fujitani, Yuji; Kyi-Tha-Thu, Chaw; Furuyama, Akiko; Michikawa, Takehiro; Tsukahara, Shinji; Nitta, Hiroshi; Hirano, Seishiro

2014-01-01

Epidemiological studies have reported an increased risk of cardiopulmonary and lung cancer mortality associated with increasing exposure to air pollution. Ambient particulate matter consists of primary particles emitted directly from diesel engine vehicles and secondary organic aerosols (SOAs) are formed by oxidative reaction of the ultrafine particle components of diesel exhaust (DE) in the atmosphere. However, little is known about the relationship between exposure to SOA and central nervous system functions. Recently, we have reported that an acute single intranasal instillation of SOA may induce inflammatory response in lung, but not in brain of adult mice. To clarify the whole body exposure effects of SOA on central nervous system functions, we first created inhalation chambers for diesel exhaust origin secondary organic aerosols (DE-SOAs) produced by oxidation of diesel exhaust particles caused by adding ozone. Male BALB/c mice were exposed to clean air (control), DE and DE-SOA in inhalation chambers for one or three months (5 h/day, 5 days/week) and were examined for memory function using a novel object recognition test and for memory function-related gene expressions in the hippocampus by real-time RT-PCR. Moreover, female mice exposed to DE-SOA for one month were mated and maternal behaviors and the related gene expressions in the hypothalamus examined. Novel object recognition ability and N-methyl-d-aspartate (NMDA) receptor expression in the hippocampus were affected in male mice exposed to DE-SOA. Furthermore, a tendency to decrease maternal performance and significantly decreased expression levels of estrogen receptor (ER)-α, and oxytocin receptor were found in DE-SOA exposed dams compared with the control. This is the first study of this type and our results suggest that the constituents of DE-SOA may be associated with memory function and maternal performance based on the impaired gene expressions in the hippocampus and hypothalamus, respectively. PMID:25361045

ETR HEAT EXCHANGER BUILDING, TRA644. METAL FRAME OF BUILDING GOES ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

ETR HEAT EXCHANGER BUILDING, TRA-644. METAL FRAME OF BUILDING GOES UP IN BACKGROUND AS WORKERS PLACE A SECTION OF WATER LINE THAT WILL CARRY SECONDARY COOLANT BETWEEN HEAT EXCHANGER BUILDING AND THE COOLING TOWER. INL NEGATIVE NO. 56-2205. Jack L. Anderson, Photographer, 6/28/1956 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

Identifying Perceptions That Contribute to the Development of Successful Project Lead the Way Pre-Engineering Programs in Utah

ERIC Educational Resources Information Center

McMullin, Keith

2013-01-01

Many secondary schools in Utah have adopted the Project Lead the Way (PLTW) pre-engineering program. Little research has been conducted in Utah to show how successful these programs are or what factors are perceived to contribute to that success. This research is about defining PLTW program success and identifying factors perceived to improve…

An Analysis of First Year Engineering Students' Satisfaction with a Support Distance Learning Program in Mathematics

ERIC Educational Resources Information Center

Matzakos, Nikolaos M.; Kalogiannakis, Michail

2018-01-01

An online support distance-learning program in Mathematics was developed to aid first year engineering students for their transition from the secondary to the tertiary education in order to reinforce deficiencies they may have in mathematical knowledge. The aim of the present study is to examine, firstly, to what extent the attendance of such a…

Cost/benefit analysis of advanced materials technologies for future aircraft turbine engines

NASA Technical Reports Server (NTRS)

Stephens, G. E.

1980-01-01

The materials technologies studied included thermal barrier coatings for turbine airfoils, turbine disks, cases, turbine vanes and engine and nacelle composite materials. The cost/benefit of each technology was determined in terms of Relative Value defined as change in return on investment times probability of success divided by development cost. A recommended final ranking of technologies was based primarily on consideration of Relative Values with secondary consideration given to changes in other economic parameters. Technologies showing the most promising cost/benefits were thermal barrier coated temperature nacelle/engine system composites.

Explore engineering with solar energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidson, J.H.

1995-11-01

An outreach program was initiated at the University of Minnesota by faculty and student members of the Society of Women Engineers in the spring of 1994 to interest students in 3rd through 9th grade, particularly girls, in careers in engineering. Interaction with elementary and junior high students focuses on hands-on experiences with portable solar devices. This paper reports progress of the program including descriptions of the solar devices, their use in visits to local schools, day visits to the University, and week-long summer camps, and continuing education programs for elementary and secondary school teachers.

Fatigue Reliability of Gas Turbine Engine Structures

NASA Technical Reports Server (NTRS)

Cruse, Thomas A.; Mahadevan, Sankaran; Tryon, Robert G.

1997-01-01

The results of an investigation are described for fatigue reliability in engine structures. The description consists of two parts. Part 1 is for method development. Part 2 is a specific case study. In Part 1, the essential concepts and practical approaches to damage tolerance design in the gas turbine industry are summarized. These have evolved over the years in response to flight safety certification requirements. The effect of Non-Destructive Evaluation (NDE) methods on these methods is also reviewed. Assessment methods based on probabilistic fracture mechanics, with regard to both crack initiation and crack growth, are outlined. Limit state modeling techniques from structural reliability theory are shown to be appropriate for application to this problem, for both individual failure mode and system-level assessment. In Part 2, the results of a case study for the high pressure turbine of a turboprop engine are described. The response surface approach is used to construct a fatigue performance function. This performance function is used with the First Order Reliability Method (FORM) to determine the probability of failure and the sensitivity of the fatigue life to the engine parameters for the first stage disk rim of the two stage turbine. A hybrid combination of regression and Monte Carlo simulation is to use incorporate time dependent random variables. System reliability is used to determine the system probability of failure, and the sensitivity of the system fatigue life to the engine parameters of the high pressure turbine. 'ne variation in the primary hot gas and secondary cooling air, the uncertainty of the complex mission loading, and the scatter in the material data are considered.

The effects of sewage discharge on water quality and phytoplankton of Hawai'ian coastal waters.

PubMed

Parnell, P Ed

2003-05-01

The effects of sewage discharge on algal populations and the quality of Hawai'ian coastal waters were investigated. Two outfalls were studied. One discharges primary treated sewage and the other discharges secondary treated sewage but are otherwise similar. This enabled comparisons of the effects of these different levels of treatment on the water quality and algal productivity of receiving waters. Plumes were followed and repeatedly sampled in a time-series manner. Rhodamine dye was used as a conservative tracer to compare the dilution behavior of the plume constituents MRP, NO(3)+NO(2), NH(4), Silicate, TDP, TDN, total bacteria, PC, and PN. Rates of initial dilution ranged from two to almost three orders of magnitude, and were in reasonable agreement with engineering model predictions. Dilution of plume constituents approximated that of Rhodamine until background concentrations were reached, typically within 10 min of discharge. Chl a concentrations did not increase through time in the primary sewage plume but did increase up to 30% in the secondary sewage plume. However, rates of far-field dilution were so rapid that the increase could not have been due to algal growth. The increase was attributed to the plume mixing with a water mass whose relative chl a concentrations were greater. Rates of secondary dilution ranged from 2 to 3 orders of magnitude resulting in total dilutions of 10(5)-10(6) within 3 h of discharge. These rates of secondary dilution were much greater than model predictions. From a nutrient standpoint, secondary treatment exhibited no advantages over primary treatment because dilutions were so rapid. Copyright 2002 Elsevier Science B.V.

Educating Tomorrow's Engineers Act

THOMAS, 113th Congress

Rep. Tonko, Paul [D-NY-20

2013-06-18

House - 07/08/2013 Referred to the Subcommittee on Early Childhood, Elementary, and Secondary Education. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

Dual-throat thruster thermal model

NASA Technical Reports Server (NTRS)

Ewen, R. L.; Obrien, C. J.; Matthews, L. W.

1986-01-01

The dual-throat engine is one of the dual nozzle engine concepts studied for advanced space transportation applications. It provides a thrust change and an in-flight area ratio change through the use of two concentric combustors with their throats arranged in series. Test results are presented for a dual throat thruster burning gaseous oxygen and hydrogen at primary (inner) chamber pressures from 380 to 680 psia. Heat flux profiles were obtained from calorimetric cooling channels in the inner nozzle, outer or secondary chamber and the tip of the inner nozzle. Data were obtained for two nozzle spacings over a chamber pressure ratio (secondary/primary) range of 0.45 to 0.83 with both chambers firing (Mode I). Fluxes near the end of the inner nozzle were significantly higher than in Mode II when only the inner chamber was fired, due to the flow separation and recirculation caused by the back pressure imposed by the secondary chamber. As the pressure ratio increased, these heat fluxes increased and the region of high heat flux relative to Mode II extended farther upstream. The use of the gaseous hydrogen bleed flow in the secondary chamber to control heat fluxes in the primary plume attachment region was investigated in Mode II testing. A thermal model of a dual throat thruster was developed and upgraded using the experimental data.

40 CFR 143.3 - Secondary maximum contaminant levels.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Secondary maximum contaminant levels... levels. The secondary maximum contaminant levels for public water systems are as follows: Contaminant Level Aluminum 0.05 to 0.2 mg/l. Chloride 250 mg/l. Color 15 color units. Copper 1.0 mg/l. Corrosivity...

Thrust and pumping characteristics of cylindrical ejectors using afterburning turbojet gas generator

NASA Technical Reports Server (NTRS)

Samanich, N. E.; Huntley, S. C.

1969-01-01

Static tests of cylindrical ejectors having ejector to primary diameter ratios from 1.1 to 1.6 and ejector length to primary nozzle diameter ratios from 0.9 to 2.1 are reported. Power setting of the J85-13 turbojet engine was varied from part power to maximum afterburning. Corrected secondary weight flow ratio was varied from 0.02 to 0.08 over a range of exhaust nozzle pressure ratios from 2.0 to 9.0. Secondary flow temperature rise and pressure drop characteristics through the nacelle secondary flow passage were also obtained.

Activities to Attract Girls to Physics in Iran

NASA Astrophysics Data System (ADS)

Izadi, Dina; Araste, Afshin Mohseni; Fadaei, Azita Seied

2009-04-01

In Iran there is no difference between boys' and girls' activities in scientific works; however, they study separately at schools until they reach the university level. Before going to university, students think engineering and medical science are better than the other sciences for earning enough money to support their lives. But after the entrance exam for universities most of the girls choose basic sciences based on their test results. Creative methods of teaching physics at the elementary and secondary levels, such as "Dominos in Physics" and "Physics in Nature," and understanding physics through real-life examples and animation are important for attracting students to further studies and careers in physics. Participating in international physics competitions and holding national tournaments and university open houses in physics is also very helpful. Studying physics can improve students' abilities and also help them to imagine, decide, think, and live better.

Exploring Factors Affecting Girls' Education at Secondary Level: A Case of Karak District, Pakistan

ERIC Educational Resources Information Center

Suleman, Qaiser; Aslam, Hassan Danial; Habib, Muhammad Badar; Yasmeen, Kausar; Jalalian, Mehrdad; Akhtar, Zaitoon; Akhtar, Basreen

2015-01-01

The study examined the factors that affect girls' education at secondary school level in Karak District, Khyber Pakhtunkhwa (Pakistan). All the female heads, teachers and students serving and studying at secondary school level in Karak District constituted the population of the study. The study was delimited to only 30 girls' secondary schools in…

Development of secondary chamber for tar cracking-improvement of wood pyrolysis performance in pre-vacuum chamber

NASA Astrophysics Data System (ADS)

Siahaan, S.; Homma, H.; Homma, H.

2018-02-01

Energy crisis and global warming, in other words, climate change are critical topics discussed in various parts of the world. Global warming primarily result from too much emission of carbon dioxide (CO2) in the atmosphere. To mitigate global warming, or climate change and improve electrification in rural areas, wood pyrolysis technology is developed in a laboratory scale, of which gases are directly applicable to the gas engine generator. Our laboratory has developed a prototype of wood pyrolysis plant with a pre-vacuum chamber. However, tar yield was around 40 wt% of feedstock. This research aims to reduce tar yield by secondary tar cracking. For the secondary tar cracking, a secondary pre-vacuum chamber is installed after primary pre-vacuum chamber. Gases generated in the primary pre-vacuum chamber are lead into the secondary chamber that is heated up to 1000 K. This paper reports performance of the secondary chamber for secondary tar cracking in homogeneous mode and heterogeneous mode with char.

Engineering Education for Innovation Act

THOMAS, 112th Congress

Rep. Tonko, Paul [D-NY-21

2011-05-23

House - 09/08/2011 Referred to the Subcommittee on Early Childhood, Elementary, and Secondary Education. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

Performance (Off-Design) Cycle Analysis for a Turbofan Engine With Interstage Turbine Burner

NASA Technical Reports Server (NTRS)

Liew, K. H.; Urip, E.; Yang, S. L.; Mattingly, J. D.; Marek, C. J.

2005-01-01

This report presents the performance of a steady-state, dual-spool, separate-exhaust turbofan engine, with an interstage turbine burner (ITB) serving as a secondary combustor. The ITB, which is located in the transition duct between the high- and the low-pressure turbines, is a relatively new concept for increasing specific thrust and lowering pollutant emissions in modern jet-engine propulsion. A detailed off-design performance analysis of ITB engines is written in Microsoft(Registered Trademark) Excel (Redmond, Washington) macrocode with Visual Basic Application to calculate engine performances over the entire operating envelope. Several design-point engine cases are pre-selected using a parametric cycle-analysis code developed previously in Microsoft(Registered Trademark) Excel, for off-design analysis. The off-design code calculates engine performances (i.e. thrust and thrust-specific-fuel-consumption) at various flight conditions and throttle settings.

Application of Adjusted Canonical Correlation Analysis (ACCA) to study the association between mathematics in Level 1 and Level 2 and performance of engineering disciplines in Level 2

NASA Astrophysics Data System (ADS)

Peiris, T. S. G.; Nanayakkara, K. A. D. S. A.

2017-09-01

Mathematics plays a key role in engineering sciences as it assists to develop the intellectual maturity and analytical thinking of engineering students and exploring the student academic performance has received great attention recently. The lack of control over covariates motivates the need for their adjustment when measuring the degree of association between two sets of variables in Canonical Correlation Analysis (CCA). Thus to examine the individual effects of mathematics in Level 1 and Level 2 on engineering performance in Level 2, two adjusted analyses in CCA: Part CCA and Partial CCA were applied for the raw marks of engineering undergraduates for three different disciplines, at the Faculty of Engineering, University of Moratuwa, Sri Lanka. The joint influence of mathematics in Level 1 and Level 2 is significant on engineering performance in Level 2 irrespective of the engineering disciplines. The individual effect of mathematics in Level 2 is significantly higher compared to the individual effect of mathematics in Level 1 on engineering performance in Level 2. Furthermore, the individual effect of mathematics in Level 1 can be negligible. But, there would be a notable indirect effect of mathematics in Level 1 on engineering performance in Level 2. It can be concluded that the joint effect of mathematics in both Level 1 and Level 2 is immensely beneficial to improve the overall academic performance at the end of Level 2 of the engineering students. Furthermore, it was found that the impact mathematics varies among engineering disciplines. As partial CCA and partial CCA are not widely explored in applied work, it is recommended to use these techniques for various applications.

Primary Emission and the Potential of Secondary Aerosol Formation from Chinese Gasoline Engine Exhaust

NASA Astrophysics Data System (ADS)

Hu, Min; Peng, Jianfei; Qin, Yanhong; Du, Zhuofei; Li, Mengjin; Zheng, Rong; Zheng, Jing; Shang, Dongjie; Lu, Sihua; Wu, Yusheng; Zeng, Limin; Guo, Song; Shao, Min; Wang, Yinhui; Shuai, Shijin

2017-04-01

Along with the urbanization and economic growth, vehicle population in China reached 269 million, ranked the second in the world in 2015. Gasoline vehicle is identified to be the main source for urban PM2.5 in China, accounting for 15%-31%. In this study the impact of fuel components on PM2.5 and volatile organic compounds (VOCs) emissions from a gasoline port fuel injection (PFI) engine and a gasoline direct injection (GDI) engine are discussed. Results show that, higher proportion of aromatics, alkenes or sulfur in gasoline fuel will lead to higher PM emissions. The PM from the PFI engine mainly consists of OC and a small amount of EC and inorganic ions, while the PM discharge from the GDI engine mainly consists of EC, OM and a small amount of inorganic ions. Since the GDI engines can reduce fuel consumption and CO2 emissions, and it would become more and more popular in the near future. The characteristics of POM component, emission factors and source profile were investigated from GDI engine, particularly focused on the effect of engine speed, load and the catalyst, which will be very much helpful for source identification as source indicators. Chamber experiments were conducted to quantify the potential of secondary aerosol formation from exhaust of a PFI gasoline engine and China V gasoline fuel. During 4-5 h simulation, equivalent to10 days of atmospheric photo-oxidation in Beijing, the extreme SOA production was 426 ± 85 mg/kg fuel, with high precursors and OH exposure. 14% of SOA measured in the chamber experiments could be explained through the oxidation of speciated single-ring aromatics. Unspeciated precursors, such as intermediate-volatility organic compounds and semi-volatility organic compounds, might be significant for SOA formation from gasoline VOCs. We concluded that reduction of emissions of aerosol precursor gases from vehicles is essential to mediate pollution in China.

Incentivizing advanced mathematics study at upper secondary level: the case of bonus points in Ireland

NASA Astrophysics Data System (ADS)

Treacy, Páraic Thomas

2018-04-01

Secondary level mathematics education in Ireland has recently experienced a period of significant change with the introduction of new curricula and the addition of an incentive to study upper secondary mathematics at the most advanced level (Higher Level). This incentive, typically referred to as 'bonus points', appears to have aided a significant increase in the number of students studying upper secondary mathematics at Higher Level. However, thematic analysis of interviews with experienced upper secondary mathematics examiners and exploration of mathematics diagnostic test data outlined in this paper suggest that the difficulty of the Higher Level upper secondary mathematics final examination in Ireland has reduced since the introduction of the bonus points initiative. The sharp increase in students attempting this examination coupled with a policy of maintaining a consistent proportion of students achieving passing grades was identified as a key reason for this possible reduction in standards.

NASA systems engineering handbook. Draft

NASA Technical Reports Server (NTRS)

Shishko, Robert; Chamberlain, Robert G.; Aster, Robert; Bilardo, Vincent; Forsberg, Kevin; Hammond, Walter E.; Mooz, Harold; Polaski, Lou; Wade, Ron; Cassingham, Randy (Editor)

1992-01-01

This handbook is intended to provide information on systems engineering that will be useful to NASA system engineers, especially new ones. Its primary objective is to provide a generic description of systems engineering as it should be applied throughout NASA. Field Center Handbooks are encouraged to provide center-specific details of implementation. For NASA system engineers to choose to keep a copy of this handbook at their elbows, it must provide answers that cannot be easily found elsewhere. Consequently, it provides NASA-relevant perspectives and NASA-particular data. NASA management instructions (NMI's) are referenced when applicable. This handbook's secondary objective is to serve as a useful companion to all of the various courses in systems engineering that are being offered under NASA's auspices. The coverage of systems engineering is general to techniques, concepts, and generic descriptions of processes, tools, and techniques. It provides good systems engineering practices, and pitfalls to avoid. This handbook describes systems engineering as it should be applied to the development of major NASA product and producing systems.

External combustor for gas turbine engine

DOEpatents

Santanam, Chandran B.; Thomas, William H.; DeJulio, Emil R.

1991-01-01

An external combustor for a gas turbine engine has a cyclonic combustion chamber into which combustible gas with entrained solids is introduced through an inlet port in a primary spiral swirl. A metal draft sleeve for conducting a hot gas discharge stream from the cyclonic combustion chamber is mounted on a circular end wall of the latter adjacent the combustible gas inlet. The draft sleeve is mounted concentrically in a cylindrical passage and cooperates with the passage in defining an annulus around the draft sleeve which is open to the cyclonic combustion chamber and which is connected to a source of secondary air. Secondary air issues from the annulus into the cyclonic combustion chamber at a velocity of three to five times the velocity of the combustible gas at the inlet port. The secondary air defines a hollow cylindrical extension of the draft sleeve and persists in the cyclonic combustion chamber a distance of about three to five times the diameter of the draft sleeve. The hollow cylindrical extension shields the drive sleeve from the inlet port to prevent discharge of combustible gas through the draft sleeve.

1999 NASA Seal/secondary Air System Workshop. Volume 1

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M. (Editor); Hendricks, Robert C. (Editor)

2000-01-01

NASA Glenn hosted the Seals/Secondary Air System Workshop on October 28-29, 1999. Each year NASA and our industry and university partners share their respective seal technology development. We use these workshops as a technical forum to exchange recent advancements and "lessons-leamed" in advancing seal technology and solving problems of common interest. As in the past we are publishing two volumes. Volume 1 will be publicly available and volume 2 will be restricted under International Traffic and Arms Regulations (I.T.A.R.). The 1999 NASA Seal/Secondary Air System Workshop was divided into four areas; (i) overviews of the government-sponsored gas turbine programs (NASA Ultra Efficient Engine Technology program and DOE Advanced Turbine System program) and the general aviation program (GAP) with emphasis on program goals and seal needs; (ii) turbine engine seal issues from the perspective of an airline customer (i.e., United Airlines), (iii) sealing concepts, methods and results including experimental facilities and numerical predictions; and (iv) reviews of seal requirements for next generation aerospace vehicles (Trailblazer, Bantam and X-38).

STEM Education: An Incongruous Approach A Proposed Reform Model for a Large Suburban High School

NASA Astrophysics Data System (ADS)

Hughes, Patricia A.

It is unknown how the school can best influence the variables that determine pursuance of science study and career choice to bring about greater opportunity to learn challenging science curriculum for all students and promote Science Technology Engineering and Mathematics (STEM) education. Student decisions regarding the type of science class to elect in early secondary school years can impact their progression and academic success in subsequent rigorous and challenging offerings. Parents, counselors, peers, gender, socio-economic status and individual experience in previous coursework are variables of consideration. The purpose of this study is to examine these variables in a large suburban New Jersey School District aligned to STEM and Advanced Placement level course choice by students. Information regarding the influence of the variables can lead to a reform of the approach toward STEM education currently in place. The study will include a historical reflection of the approach to curriculum revision in the district. Increasing student enrollment in science courses beyond the required number stipulated for high school completion will open opportunities for entrance into STEM related careers or continued post secondary science study.

Recovery Act - Sustainable Transportation: Advanced Electric Drive Vehicle Education Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caille, Gary

The collective goals of this effort include: 1) reach all facets of this society with education regarding electric vehicles (EV) and plug–in hybrid electric vehicles (PHEV), 2) prepare a workforce to service these advanced vehicles, 3) create web–based learning at an unparalleled level, 4) educate secondary school students to prepare for their future and 5) train the next generation of professional engineers regarding electric vehicles. The Team provided an integrated approach combining secondary schools, community colleges, four–year colleges and community outreach to provide a consistent message (Figure 1). Colorado State University Ventures (CSUV), as the prime contractor, plays a keymore » program management and co–ordination role. CSUV is an affiliate of Colorado State University (CSU) and is a separate 501(c)(3) company. The Team consists of CSUV acting as the prime contractor subcontracted to Arapahoe Community College (ACC), CSU, Motion Reality Inc. (MRI), Georgia Institute of Technology (Georgia Tech) and Ricardo. Collaborators are Douglas County Educational Foundation/School District and Gooru (www.goorulearning.org), a nonprofit web–based learning resource and Google spin–off.« less

Performance Cycle Analysis of a Two-Spool, Separate-Exhaust Turbofan With Interstage Turbine Burner

NASA Technical Reports Server (NTRS)

Liew, K. H.; Urip, E.; Yang, S. L.; Mattingly, J. D.; Marek, C. J.

2005-01-01

This paper presents the performance cycle analysis of a dual-spool, separate-exhaust turbofan engine, with an Interstage Turbine Burner serving as a secondary combustor. The ITB, which is located at the transition duct between the high- and the low-pressure turbines, is a relatively new concept for increasing specific thrust and lowering pollutant emissions in modern jet engine propulsion. A detailed performance analysis of this engine has been conducted for steady-state engine performance prediction. A code is written and is capable of predicting engine performances (i.e., thrust and thrust specific fuel consumption) at varying flight conditions and throttle settings. Two design-point engines were studied to reveal trends in performance at both full and partial throttle operations. A mission analysis is also presented to assure the advantage of saving fuel by adding ITB.

Fall 2016 Solicitation Projects Website Info

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diachin, L.

Spark-ignition engines are the backbone behind people transportation around the world. The efficiency of spark-ignition engines is limited in practice by variations between engine cycles and cylinders within an engine that result from the manufacturing processes/tolerances. These variations impact knock limits and dilution tolerance, which results in more conservative settings for design and calibration settings, such as compression ratio, valve timing, and exhaust gas recirculation rates. Engine variations also have a significant impact on emissions generation, which can have a secondary impact on efficiency. A deeper understanding of the relative importance of these variations and their interactions on the chargemore » preparation process can guide future decisions on machining tolerances and control strategies. This project will develop simulation tools and methodology to include the effects of some key manufacturing tolerances and their impact on engine performance and emissions.« less

Curriculum Reform and Restructuring of Senior Secondary Science Education in Hong Kong: Teachers' Perceptions and Implications

ERIC Educational Resources Information Center

Yeung, Yau-Yuen; Lee, Yeung-Chung; Lam, Irene Chung-Man

2012-01-01

With the restructuring of the senior secondary education system in Hong Kong in 2009, the senior secondary curriculum was overhauled substantially by the conversion of the two-year Certificate Level and the two-year Advanced Level to a new three-year senior secondary level. This process entails changes to the contents and organization of various…

Changing Socio-Economic Structures and the Challenge of Secondary Schooling: Voices from a Village in Odisha

ERIC Educational Resources Information Center

Chakraborty, Suchita

2016-01-01

Secondary education has been a relatively neglected area in India, both at the level of policy and research. Statistical data at the secondary level of education reveals a bleak picture in terms of enrolment and completion rates. This article explores the underlying reasons for the dismal scenario at the secondary level of education by situating…

What Role Do We Expect Secondary Master Reading Teachers to Play?

ERIC Educational Resources Information Center

Savitz, Rachelle S.; Rasinski, Timothy

2018-01-01

In this article, we explore and identify the varied roles that have been assigned over time to the master reading teacher at the secondary level. Despite the fact that there are fewer master reading teachers (MRTs) at the secondary level, they are often required to take on even more responsibilities than MRTs at the elementary level. Secondary MRT…

The Influence of Parents Educational Level on Secondary School Students Academic Achievements in District Rajanpur

ERIC Educational Resources Information Center

Khan, Rana Muhammad Asad; Iqbal, Nadeem; Tasneem, Saima

2015-01-01

This study was conducted to focus the influence and impact of parents educational level on students academic achievement at secondary level of education. The study utilizes the students results of the 9th class in secondary school certificate examination taken by the Board of Intermediate & Secondary Education Dera Ghazi Khan. Oral interview,…

The Technician's Peer Groups: A Review of Some Research on High School Students. Engineering Technology Education Study Report No. 5.

ERIC Educational Resources Information Center

Defore, Jesse J.

This paper describes briefly the secondary education milieu from which has come students in engineering technology education programs. The paper is based entirely on the published reports of other writers and is intended only to provide an overview of the research which has been done on the American high school, on American high school students,…

PR[superscript 2]EPS: Preparation, Recruitment, Retention and Excellence in the Physical Sciences, Including Engineering. A Report on the 2004, 2005 and 2006 Science Summer Camps

ERIC Educational Resources Information Center

Bachman, Nancy J.; Bischoff, Paul J.; Gallagher, Hugh; Labroo, Sunil; Schaumloffel, John C.

2008-01-01

Now in its fourth year, PR[superscript 2]EPS is a National Science Foundation funded initiative designed to recruit high school students to attend college majoring in the physical sciences, including engineering and secondary science education, and to help ensure their retention within the program until graduation. A central feature of the…

USAF Aircraft Engine Emission Goals: A Critical Review.

DTIC Science & Technology

1979-09-01

21 June 1965 and Change 1; and the National Pollution Discharge Elimination System . it applies to all Air Force installations and facilities, the Air...the combustion problems in turbine engines from a more applied viewpoint. He states: "While the combustion system was the primary limitation in... microemulsions and to determine their capacity for reducing smoke emissions from an aviation gas turbine combustion system . (2) A secondary objective is

Metabolic Engineering of the Shikimate Pathway for Production of Aromatics and Derived Compounds—Present and Future Strain Construction Strategies

PubMed Central

Averesch, Nils J. H.; Krömer, Jens O.

2018-01-01

The aromatic nature of shikimate pathway intermediates gives rise to a wealth of potential bio-replacements for commonly fossil fuel-derived aromatics, as well as naturally produced secondary metabolites. Through metabolic engineering, the abundance of certain intermediates may be increased, while draining flux from other branches off the pathway. Often targets for genetic engineering lie beyond the shikimate pathway, altering flux deep in central metabolism. This has been extensively used to develop microbial production systems for a variety of compounds valuable in chemical industry, including aromatic and non-aromatic acids like muconic acid, para-hydroxybenzoic acid, and para-coumaric acid, as well as aminobenzoic acids and aromatic α-amino acids. Further, many natural products and secondary metabolites that are valuable in food- and pharma-industry are formed outgoing from shikimate pathway intermediates. (Re)construction of such routes has been shown by de novo production of resveratrol, reticuline, opioids, and vanillin. In this review, strain construction strategies are compared across organisms and put into perspective with requirements by industry for commercial viability. Focus is put on enhancing flux to and through shikimate pathway, and engineering strategies are assessed in order to provide a guideline for future optimizations. PMID:29632862

Long-term trends in California mobile source emissions and ambient concentrations of black carbon and organic aerosol.

PubMed

McDonald, Brian C; Goldstein, Allen H; Harley, Robert A

2015-04-21

A fuel-based approach is used to assess long-term trends (1970-2010) in mobile source emissions of black carbon (BC) and organic aerosol (OA, including both primary emissions and secondary formation). The main focus of this analysis is the Los Angeles Basin, where a long record of measurements is available to infer trends in ambient concentrations of BC and organic carbon (OC), with OC used here as a proxy for OA. Mobile source emissions and ambient concentrations have decreased similarly, reflecting the importance of on- and off-road engines as sources of BC and OA in urban areas. In 1970, the on-road sector accounted for ∼90% of total mobile source emissions of BC and OA (primary + secondary). Over time, as on-road engine emissions have been controlled, the relative importance of off-road sources has grown. By 2010, off-road engines were estimated to account for 37 ± 20% and 45 ± 16% of total mobile source contributions to BC and OA, respectively, in the Los Angeles area. This study highlights both the success of efforts to control on-road emission sources, and the importance of considering off-road engine and other VOC source contributions when assessing long-term emission and ambient air quality trends.

Linking Load, Fuel, and Emission Controls to Photochemical Production of Secondary Organic Aerosol from a Diesel Engine.

PubMed

Jathar, Shantanu H; Friedman, Beth; Galang, Abril A; Link, Michael F; Brophy, Patrick; Volckens, John; Eluri, Sailaja; Farmer, Delphine K

2017-02-07

Diesel engines are important sources of fine particle pollution in urban environments, but their contribution to the atmospheric formation of secondary organic aerosol (SOA) is not well constrained. We investigated direct emissions of primary organic aerosol (POA) and photochemical production of SOA from a diesel engine using an oxidation flow reactor (OFR). In less than a day of simulated atmospheric aging, SOA production exceeded POA emissions by an order of magnitude or more. Efficient combustion at higher engine loads coupled to the removal of SOA precursors and particle emissions by aftertreatment systems reduced POA emission factors by an order of magnitude and SOA production factors by factors of 2-10. The only exception was that the retrofitted aftertreatment did not reduce SOA production at idle loads where exhaust temperatures were low enough to limit removal of SOA precursors in the oxidation catalyst. Use of biodiesel resulted in nearly identical POA and SOA compared to diesel. The effective SOA yield of diesel exhaust was similar to that of unburned diesel fuel. While OFRs can help study the multiday evolution, at low particle concentrations OFRs may not allow for complete gas/particle partitioning and bias the potential of precursors to form SOA.

Engineering-Scale Demonstration of DuraLith and Ceramicrete Waste Forms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Josephson, Gary B.; Westsik, Joseph H.; Pires, Richard P.

2011-09-23

To support the selection of a waste form for the liquid secondary wastes from the Hanford Waste Immobilization and Treatment Plant, Washington River Protection Solutions (WRPS) has initiated secondary waste form testing on four candidate waste forms. Two of the candidate waste forms have not been developed to scale as the more mature waste forms. This work describes engineering-scale demonstrations conducted on Ceramicrete and DuraLith candidate waste forms. Both candidate waste forms were successfully demonstrated at an engineering scale. A preliminary conceptual design could be prepared for full-scale production of the candidate waste forms. However, both waste forms are stillmore » too immature to support a detailed design. Formulations for each candidate waste form need to be developed so that the material has a longer working time after mixing the liquid and solid constituents together. Formulations optimized based on previous lab studies did not have sufficient working time to support large-scale testing. The engineering-scale testing was successfully completed using modified formulations. Further lab development and parametric studies are needed to optimize formulations with adequate working time and assess the effects of changes in raw materials and process parameters on the final product performance. Studies on effects of mixing intensity on the initial set time of the waste forms are also needed.« less

Microfluidic Bioprinting for Engineering Vascularized Tissues and Organoids.

PubMed

Zhang, Yu Shrike; Pi, Qingmeng; van Genderen, Anne Metje

2017-08-11

Engineering vascularized tissue constructs and organoids has been historically challenging. Here we describe a novel method based on microfluidic bioprinting to generate a scaffold with multilayer interlacing hydrogel microfibers. To achieve smooth bioprinting, a core-sheath microfluidic printhead containing a composite bioink formulation extruded from the core flow and the crosslinking solution carried by the sheath flow, was designed and fitted onto the bioprinter. By blending gelatin methacryloyl (GelMA) with alginate, a polysaccharide that undergoes instantaneous ionic crosslinking in the presence of select divalent ions, followed by a secondary photocrosslinking of the GelMA component to achieve permanent stabilization, a microfibrous scaffold could be obtained using this bioprinting strategy. Importantly, the endothelial cells encapsulated inside the bioprinted microfibers can form the lumen-like structures resembling the vasculature over the course of culture for 16 days. The endothelialized microfibrous scaffold may be further used as a vascular bed to construct a vascularized tissue through subsequent seeding of the secondary cell type into the interstitial space of the microfibers. Microfluidic bioprinting provides a generalized strategy in convenient engineering of vascularized tissues at high fidelity.

Co-transport of gold nanospheres with single-walled carbon nanotubes in saturated porous media.

PubMed

Afrooz, A R M Nabiul; Das, Dipesh; Murphy, Catherine J; Vikesland, Peter; Saleh, Navid B

2016-08-01

Porous media transport of engineered nanomaterials (ENMs) is typically assessed in a controlled single-particulate environment. Presence of a secondary particle (either natural or engineered) in the natural environment though likely, is rarely taken into consideration in assessing ENMs' transport behavior. This study systematically assesses the effect of a secondary ENM (i.e., pluronic acid modified single-walled carbon nanotubes, PA-SWNTs) on a primary particle (i.e., gold nanospheres, AuNSs) transport through saturated porous media under a wide range of aquatic conditions (1-100 mM NaCl). AuNS hetero-dispersions (i.e., with PA-SWNTs) are transported through saturated sand columns, and the transport behavior is compared to AuNS-only homo-dispersion cases, which display classical ionic strength-dependent behavior. AuNS hetero-dispersion, however, is highly mobile with little to no ionic strength-dependent effects. This study also assesses the role of pre-coating of the collectors with PA-SWNTs on AuNSs' mobility, thereby elucidating the role played by the order of introduction of the secondary particles. Pre-existence of the secondary particles in the porous media shows enhanced filtration of primary AuNSs. However, the presence of natural organic matter (NOM) slightly increases AuNS mobility through PA-SWNT coated sand at 10 mM ionic strength. The study results demonstrate that the presence and order of addition of the secondary particles strongly influence primary particles' mobility. Thus ENMs can demonstrate facilitated transport or enhanced removal, depending on the presence of the secondary particulate matter and background solution chemistry. Copyright © 2016 Elsevier Ltd. All rights reserved.

Snapshots of Authentic Scientific Inquiry and Teacher Preparation: Undergraduate STEM Courses, Preservice and Inservice Teachers' Experiences

NASA Astrophysics Data System (ADS)

French, Debbie Ann

In this dissertation, the researcher describes authentic scientific inquiry (ASI) within three stages of teacher preparation and development: a1) undergraduate STEM courses, b2) preservice secondary science education methods courses, and c3) inservice teacher professional development (PD). Incorporating (ASI)-- pedagogy closely modeling the research practices of scientists--is at the forefront of national science, technology, engineering, and mathematics (STEM) initiatives and the Next Generation Science Standards (NGSS). In the first of three research articles, 42 students participated in an introductory astronomy course which employed inquiry-based pedagogy. The researcher administered the Test Of Astronomy STandards (TOAST) pre/post instruction. In the second article, 56 preservice secondary science teachers completed ideal lesson plan scenarios before and after 80 hours of methods instruction. The researcher scored the scenarios using a rubrirubric developedc according to the NGSS Science and Engineering Practices, and analyzed the components from the scenarios. The third article surveyed 63 inservice STEM teachers with prior research and industry experience. The researcher highlights teacher ASI perspectives. Overall, teachers incorporated opportunities for K-20 students to use scientific instrumentation and technology to collect and analyze data, work collaboratively, and develop evidence-based conclusions. Few teachers provided opportunities for students to ask scientific questions or disseminate results, suggesting the need that teachers (at all levels) need scaffolded instruction in these areas. The researcher argues that while ASI and STEM PDs are effective for teachers, developing similar interest, on-going communities of practice may provide support for teacher to implement the ASI practices in their classrooms.

EmptyHeaded: A Relational Engine for Graph Processing

PubMed Central

Aberger, Christopher R.; Tu, Susan; Olukotun, Kunle; Ré, Christopher

2016-01-01

There are two types of high-performance graph processing engines: low- and high-level engines. Low-level engines (Galois, PowerGraph, Snap) provide optimized data structures and computation models but require users to write low-level imperative code, hence ensuring that efficiency is the burden of the user. In high-level engines, users write in query languages like datalog (SociaLite) or SQL (Grail). High-level engines are easier to use but are orders of magnitude slower than the low-level graph engines. We present EmptyHeaded, a high-level engine that supports a rich datalog-like query language and achieves performance comparable to that of low-level engines. At the core of EmptyHeaded’s design is a new class of join algorithms that satisfy strong theoretical guarantees but have thus far not achieved performance comparable to that of specialized graph processing engines. To achieve high performance, EmptyHeaded introduces a new join engine architecture, including a novel query optimizer and data layouts that leverage single-instruction multiple data (SIMD) parallelism. With this architecture, EmptyHeaded outperforms high-level approaches by up to three orders of magnitude on graph pattern queries, PageRank, and Single-Source Shortest Paths (SSSP) and is an order of magnitude faster than many low-level baselines. We validate that EmptyHeaded competes with the best-of-breed low-level engine (Galois), achieving comparable performance on PageRank and at most 3× worse performance on SSSP. PMID:28077912

Energy efficiency as a commodity: The emergence of a secondary market for efficiency savings in commercial buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kats, G.H.; Rosenfield, A.H.; McIntosh, T.A.

1997-06-01

The energy efficiency industry is constrained by lack of financing. For example, in the United States, commercial and public buildings need an investment of $100 billion for cost-effective retrofits with an average payback of about four years. But the current level of financing is stagnant at only about 34% of this level per year. The U.S. Department of Energy (DOE) has led the development of the North American Energy Measurement and Verification Protocol (NEMVP). This Protocol will increase the reliability and quality of estimated efficiency savings and improve realized savings. A critical element in the development of low cost financingmore » and a secondary market--whether for homes or credit card debt--is the adoption of protocols to provide uniformity and reliability of the product. This is also true of energy efficiency installations, which have been characterized by inconsistency in the installation methodologies and, frequently, unreliability of savings. This Protocol, published in April 1996, is a DOE-led effort involving American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. ASHRAE, National Association of Energy Service Companies NAESCO, National Association of Regulatory Utility Commissioners NARUC, National Association of State Energy Officials NASEO, US Environmental Protection Agency EPA, Canada`s Canadian Association of Energy Service Companies CAESCO, and Mexico`s Comision Nacional Para El Ahorro De Energia CONAE and Fideicomiso De Apoyo Al Programa De Ahorro De Energia Del Sector Electrico FIDE. DOE has begun to build on this Protocol to develop new forms of lower-cost financing including, ultimately, development of a secondary market for energy efficiency. This could double financing for building energy efficiency within five years.« less

Advanced Gas Turbine (AGT) powertrain system development for automotive applications

NASA Technical Reports Server (NTRS)

1981-01-01

Preliminary layouts were made for the exhaust system, air induction system, and battery installation. Points of interference were identified and resolved by altering either the vehicle or engine designs. An engine general arrangement evolved to meet the vehicle engine compartment constraints while minimizing the duct pressure losses and the heat rejection. A power transfer system (between gasifier and power turbines) was developed to maintain nearly constant temperatures throughout the entire range of engine operation. An advanced four speed automatic transmission was selected to be used with the engine. Performance calculations show improvements in component efficiencies and an increase in fuel economy. A single stage centrifugal compressor design was completed and released for procurement. Gasifier turbine, power turbine, combustor, generator, secondary systems, materials, controls, and transmission development are reported.

A Sense of Balance: Experimental Investigation and Modeling of a Malonyl-CoA Sensor in Escherichia coli.

PubMed

Fehér, Tamás; Libis, Vincent; Carbonell, Pablo; Faulon, Jean-Loup

2015-01-01

Production of value-added chemicals in microorganisms is regarded as a viable alternative to chemical synthesis. In the past decade, several engineered pathways producing such chemicals, including plant secondary metabolites in microorganisms have been reported; upscaling their production yields, however, was often challenging. Here, we analyze a modular device designed for sensing malonyl-CoA, a common precursor for both fatty acid and flavonoid biosynthesis. The sensor can be used either for high-throughput pathway screening in synthetic biology applications or for introducing a feedback circuit to regulate production of the desired chemical. Here, we used the sensor to compare the performance of several predicted malonyl-CoA-producing pathways, and validated the utility of malonyl-CoA reductase and malonate-CoA transferase for malonyl-CoA biosynthesis. We generated a second-order dynamic linear model describing the relation of the fluorescence generated by the sensor to the biomass of the host cell representing a filter/amplifier with a gain that correlates with the level of induction. We found the time constants describing filter dynamics to be independent of the level of induction but distinctively clustered for each of the production pathways, indicating the robustness of the sensor. Moreover, by monitoring the effect of the copy-number of the production plasmid on the dose-response curve of the sensor, we managed to coarse-tune the level of pathway expression to maximize malonyl-CoA synthesis. In addition, we provide an example of the sensor's use in analyzing the effect of inducer or substrate concentrations on production levels. The rational development of models describing sensors, supplemented with the power of high-throughput optimization provide a promising potential for engineering feedback loops regulating enzyme levels to maximize productivity yields of synthetic metabolic pathways.

The prediction of noise and installation effects of high-subsonic dual-stream jets in flight

NASA Astrophysics Data System (ADS)

Saxena, Swati

Both military and civil aircraft in service generate high levels of noise. One of the major contributors to this noise generated from the aircraft is the jet engine exhaust. This makes the study of jet noise and methods to reduce jet noise an active research area with the aim of designing quieter military and commercial aircraft. The current stringent aircraft noise regulations imposed by the Federal Aviation Administration (FAA) and other international agencies, have further raised the need to perform accurate jet noise calculations for more reliable estimation of the jet noise sources. The main aim of the present research is to perform jet noise simulations of single and dual-stream jets with engineering accuracy and assess forward flight effects on the jet noise. Installation effects such as caused by the pylon are also studied using a simplified pylon nozzle configuration. Due to advances in computational power, it has become possible to perform turbulent flow simulations of high speed jets, which leads to more accurate noise predictions. In the present research, a hybrid unsteady RANS-LES parallel multi-block structured grid solver called EAGLEJet is written to perform the nozzle flow calculations. The far-field noise calculation is performed using solutions to the Ffowcs Williams and Hawkings equation. The present calculations use meshes with 5 to 11 million grid points and require about three weeks of computing time with about 100 processors. A baseline single stream convergent nozzle and a dual-stream coaxial convergent nozzle are used for the flow and noise analysis. Calculations for the convergent nozzle are performed at a high subsonic jet Mach number of Mj = 0.9, which is similar to the operating conditions for commercial aircraft engines. A parallel flow gives the flight effect, which is simulated with a co-flow Mach number, Mcf varying from 0.0 to 0.28. The grid resolution effects, statistical properties of the turbulence and the heated jet effects ( TTR = 2.7) are studied and related to the noise characteristics of the jet. Both flow and noise predictions show good agreement with PIV and microphone measurements. The potential core lengths and nozzle wall boundary characteristics are studied to understand the differences between the numerical potential core lengths as compared to experiments. The flight velocity exponent, m is calculated from the noise reduction in overall sound pressure levels (OASPL, dB) and relative velocity (V j -- Vcf) at all jet inlet (angular) angles. The variation of the exponent, m at lower (50° to 90°) and higher aft inlet angles (120° to 150°) is studied and compared with available measurements. Previous studies have shown a different variation of the exponent with inlet angles while the current numerical data match well with recent experiments conducted on the same nozzle geometry. Today, turbofans are the most efficient engines in service used in almost all major commercial aircraft. Turbofans have a dual-stream exhaust nozzle with primary and secondary flow whose flow and noise characteristics are different from that of single stream jets. A Boeing-designed coaxial nozzle, with area ratio of As/Ap = 3.0, is used to study dual-stream jet noise in the present research. In this configuration, the primary nozzle extends beyond the secondary nozzle, which is representative of large turbofan engines in commercial service. The flow calculations are performed at high subsonic Mach numbers in the primary and secondary nozzles (Mpj = 0.85, Msj = 0.95) with heated core flow, TTRp = 2.26 and unheated fan flow, TTRs = 1.0. The co-flow of Mcf = 0.2 is used. The subscript p, s and amb represent the primary (core) nozzle, the secondary (fan) nozzle, and the ambient flow conditions, respectively. The statistical properties in the primary and secondary shear layers are studied and compared with those of the single stream jets. It has been found that the eddy convection velocity is lower in dual-stream jets as compared to the single stream jet operating at a similar jet exit Mach number. The phase velocity is higher in the secondary shear layer as compared to primary shear layer. The noise measurements agree well with the predicted data and noise reduction is observed in the presence of co-flow. The variation of the flight velocity exponent is calculated as a function of nozzle inlet angle. The value of the exponent at higher inlet angles is lower as compared to the single stream jets. This suggests that the noise levels are less affected in the peak noise direction in the presence of co-flow in dual-stream jets as compared to single stream jets. Two reference velocities: primary jet exit velocity Vpj and mixed velocity Vmix are considered which result in different absolute values of the exponents. Scaling of the jet spectra is performed at different inlet angles and good collapse has been obtained between the spectra. The installation effects on jet noise are studied using a simplified pylon structure with a dual-stream nozzle. In the presence of a pylon, the azimuthal symmetry of the nozzle is lost and thus the flow characteristics are different as compared to the baseline nozzle. This will result in different noise characteristics of the installed jet.

Institute for Scientific and Educational Technology (ISET)-Education, Research and Training Programs in Engineering and Sciences

NASA Technical Reports Server (NTRS)

Tiwari, S. N. (Principal Investigator); Massenberg, Samuel E. (Technical Monitor)

2002-01-01

The 'Institute for Scientific and Educational Technology' has been established to provide a mechanism through which universities and other research organizations may cooperate with one another and with different government agencies and industrial organizations to further and promote research, education, and training programs in science, engineering, and related fields. This effort has been undertaken consistent with the national vision to 'promote excellence in America s educational system through enhancing and expanding scientific and technological competence.' The specific programs are directed in promoting and achieving excellence for individuals at all levels (elementary and secondary schools, undergraduate and graduate education, and postdoctoral and faculty research). The program is consistent with the existing activities of the Institute for Computational and Applied Mechanics (ICAM) and the American Society for Engineering Education (ASEE) at NASA Langley Research Center (LaRC). The efforts will be directed to embark on other research, education, and training activities in various fields of engineering, scientific, and educational technologies. The specific objectives of the present program may be outlined briefly as follows: 1) Cooperate in the various research, education, and technology programs of the Office of Education at LaRC. 2) Develop procedures for interactions between precollege, college, and graduate students, and between faculty and students at all levels. 3) Direct efforts to increase the participation by women and minorities in educational programs at all levels. 4) Enhance existing activities of ICAM and ASEE in education, research, and training of graduate students and faculty. 5) Invite distinguished scholars as appropriate and consistent with ISET goals to spend their summers and/or sabbaticals at NASA Langley andor ODU and interact with different researchers and graduate students. Perform research and administrative activities as needed to carry out the above mentioned activities. 6) The implementation of various activities of the ISET programs is carried out through cooperative efforts between Old Dominion University (ODU) and the Office of Education at LaRC. At present, major efforts are directed on the following ISET Programs: ICAM Programs, Academic Programs, Educational Research, Outreach Programs, Educational Technology and Cooperative Programs. These programs are described in the following sections.

ANSYS UIDL-Based CAE Development of Axial Support System for Optical Mirror

NASA Astrophysics Data System (ADS)

Yang, De-Hua; Shao, Liang

2008-09-01

The Whiffle-tree type axial support mechanism is widely adopted by most relatively large optical mirrors. Based on the secondary developing tools offered by the commonly used Finite Element Anylysis (FEA) software ANSYS, ANSYS Parametric Design Language (APDL) is used for creating the mirror FEA model driven by parameters, and ANSYS User Interface Design Language (UIDL) for generating custom menu of interactive manner, whereby, the relatively independent dedicated Computer Aided Engineering (CAE) module is embedded in ANSYS for calculation and optimization of axial Whiffle-tree support of optical mirrors. An example is also described to illustrate the intuitive and effective usage of the dedicated module by boosting work efficiency and releasing related engineering knowledge of user. The philosophy of secondary-developed special module with commonly used software also suggests itself for product development in other industries.

Engine balance apparatus and accessory drive device

NASA Technical Reports Server (NTRS)

Egleston, Robert W. (Inventor)

2002-01-01

A balancing mechanism for an engine that has a rotating crankshaft and reciprocating pistons. The balancing mechanism comprises a primary balance mass assembly non-rotatably and removably affixed to the crankshaft. The primary mass assembly comprises a primary mass affixed to a primary hub portion and a primary cap portion removably affixed to the primary hub portion to clamp a portion of the crankshaft therebetween. A secondary balance mass assembly may be rotatably and removably supported on the crankshaft. A driver assembly is affixed to the crankshaft to cause the secondary balance mass to rotate in a direction that is opposite to the direction in which the crank shaft is rotating. The driver assembly may include auxiliary gears configured to transport rotary power to auxiliary components. The gears are readily detachable from the apparatus to facilitate inspection and repair operations.

The role of non-epistemic values in engineering models.

PubMed

Diekmann, Sven; Peterson, Martin

2013-03-01

We argue that non-epistemic values, including moral ones, play an important role in the construction and choice of models in science and engineering. Our main claim is that non-epistemic values are not only "secondary values" that become important just in case epistemic values leave some issues open. Our point is, on the contrary, that non-epistemic values are as important as epistemic ones when engineers seek to develop the best model of a process or problem. The upshot is that models are neither value-free, nor depend exclusively on epistemic values or use non-epistemic values as tie-breakers.

A Sustainable Energy Laboratory Course for Non-Science Majors

NASA Astrophysics Data System (ADS)

Nathan, Stephen A.; Loxsom, Fred

2016-10-01

Sustainable energy is growing in importance as the public becomes more aware of climate change and the need to satisfy our society's energy demands while minimizing environmental impacts. To further this awareness and to better prepare a workforce for "green careers," we developed a sustainable energy laboratory course that is suitable for high school and undergraduate students, especially non-science majors. Thirteen hands-on exercises provide an overview of sustainable energy by demonstrating the basic principles of wind power, photovoltaics, electric cars, lighting, heating/cooling, insulation, electric circuits, and solar collectors. The order of content presentation and instructional level (secondary education or college) can easily be modified to suit instructor needs and/or academic programs (e.g., engineering, physics, renewable and/or sustainable energy).

Identification of signatory secondary metabolites during mycoparasitism of Rhizoctonia solani by Stachybotrys elegans

PubMed Central

Chamoun, Rony; Aliferis, Konstantinos A.; Jabaji, Suha

2015-01-01

Stachybotrys elegans is able to parasitize the fungal plant pathogen Rhizoctonia solani AG-3 following a complex and intimate interaction, which, among others, includes the production of cell wall-degrading enzymes, intracellular colonization, and expression of pathogenic process encoding genes. However, information on the metabolome level is non-existent during mycoparasitism. Here, we performed a direct-infusion mass spectrometry (DIMS) metabolomics analysis using an LTQ Orbitrap analyzer in order to detect changes in the profiles of induced secondary metabolites of both partners during this mycoparasitic interaction 4 and 5 days following its establishment. The diketopiperazine(s) (DKPs) cyclo(S-Pro-S-Leu)/cyclo(S-Pro-S-Ile), ethyl 2-phenylacetate, and 3-nitro-4-hydroxybenzoic acid were detected as the primary response of Rhizoctonia 4 days following dual-culturing with Stachybotrys, whereas only the latter metabolite was up-regulated 1 day later. On the other hand, trichothecenes and atranones were mycoparasite-derived metabolites identified during mycoparasitism 4 and 5 days following dual-culturing. All the above secondary metabolites are known to exhibit bioactivity, including fungitoxicity, and represent key elements that determine the outcome of the interaction being studied. Results could be further exploited in programs for the evaluation of the bioactivity of these metabolites per se or their chemical analogs, and/or genetic engineering programs to obtain more efficient mycoparasite strains with improved efficacy and toxicological profiles. PMID:25972848

Incentivizing Advanced Mathematics Study at Upper Secondary Level: The Case of Bonus Points in Ireland

ERIC Educational Resources Information Center

Treacy, Páraic Thomas

2018-01-01

Secondary level mathematics education in Ireland has recently experienced a period of significant change with the introduction of new curricula and the addition of an incentive to study upper secondary mathematics at the most advanced level (Higher Level). This incentive, typically referred to as 'bonus points', appears to have aided a significant…

Brazilian actions to promote physiology learning and teaching in secondary and high schools.

PubMed

Mello-Carpes, Pâmela B; Granjeiro, Érica Maria; Montrezor, Luís Henrique; Rocha, Maria José Alves

2016-06-01

Members of the Education Committee of the Brazilian Society of Physiology have developed multiple outreach models to improve the appreciation of science and physiology at the precollege level. The members of this committee act in concert with important Brazilian governmental strategies to promote training of undergraduate students in the teaching environment of secondary and high schools. One of these governmental strategies, the Programa Institucional de Bolsas de Iniciação à Docência, a Brazilian public policy of teaching enhancement implemented by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) since 2007, represents a well-articulated public policy that can promote the partnership between University and Schools (7). Furthermore, the Program "Novos Talentos" (New Talents)/CAPES/Ministry of Education is another government initiative to bring together university and high-level technical training with the reality of Brazilian schools. Linked to the New Talents Program, in partnership with the British Council/Newton Fund, CAPES recently promoted the visit of some university professors that coordinate New Talents projects to formal and informal educational science spaces in the United Kingdom (Science, Technology, Engineering, and Mathematics, Brazil-United Kingdom International Cooperation Program) to qualify the actions developed in this area in Brazil, and one of us had the opportunity to participate with this. Copyright © 2016 The American Physiological Society.

REVIEW ARTICLE: Industrial applications of temperature and species concentration monitoring using laser diagnostics

NASA Astrophysics Data System (ADS)

Deguchi, Y.; Noda, M.; Fukuda, Y.; Ichinose, Y.; Endo, Y.; Inada, M.; Abe, Y.; Iwasaki, S.

2002-10-01

Industrial applications of laser diagnostics have been demonstrated for the purpose of clarifying combustor chemical reaction mechanisms, as well as temperature and harmful substance monitoring in large-scale burners and commercial plant exhaust ducts, and the combustion control of commercial plants. Laser induced fluorescence (LIF), laser induced breakdown spectroscopy (LIBS), and tunable diode laser absorption spectroscopy (TDLAS) have accordingly been applied in various industrial fields. In this study, temperature and species concentration were measured inside gas turbine combustors, a diesel engine, and a large-scale industrial burner using LIF. This technique introduces a new tool with respect to practical combustors for the analysis of NO formation characteristics, turbulent flame front structure, and differences between standard and improved combustors. On-line monitoring of trace elements to the ppb level was also successfully demonstrated using LIBS. The automated LIBS unit was found to be capable of monitoring trace element concentration fluctuations at ppb levels with a 1 min detection time under actual plant conditions. In addition, real-time measurement of O2 and CO concentrations in a commercial incinerator furnace was performed using TDLAS to improve the combustion control. By using the multiple-point laser measurement results to control secondary air allocation, higher secondary combustion efficiency was achieved, and CO concentration (considered to be a substitute indicator for dioxins) was reduced from 11.9 to 8.0 ppm.

Pairwise amino acid secondary structural propensities

NASA Astrophysics Data System (ADS)

Chemmama, Ilan E.; Chapagain, Prem P.; Gerstman, Bernard S.

2015-04-01

We investigate the propensities for amino acids to form a specific secondary structure when they are paired with other amino acids. Our investigations use molecular dynamics (MD) computer simulations, and we compare the results to those from the Protein Data Bank (PDB). Proper comparison requires weighting of the MD results in a manner consistent with the relative frequency of appearance in the PDB of each possible pair of amino acids. We find that the propensity for an amino acid to assume a secondary structure varies dramatically depending on the amino acid that is before or after it in the primary sequence. This cooperative effect means that when selecting amino acids to facilitate the formation of a secondary structure in peptide engineering experiments, the adjacent amino acids must be considered. We also examine the preference for a secondary structure in bacterial proteins and compare the results to those of human proteins.

Corps of Engineers Land Treatment of Wastewater Research Program, An Annotated Bibliography.

DTIC Science & Technology

1983-04-01

engineering) Waste treatment Waste water 4 20. ABST14ACT (Eacabsue an reverse oh It necwwey mad tdertlfy by block number) *This bibliography contains...1982) Distribution of phosphorus in soils irri ated with municipal waste- water effluent: A 5-year study. Journal of Environmental Quality, vol. 11...vol. 44, p. 383-394. The removal of seeded coliphage f2 and indigenous enteroviruses from primary and secondary wastewaters applied by spray

Teaching biomedical applications to secondary students.

PubMed

Openshaw, S; Fleisher, A; Ljunggren, C

1999-01-01

Certain aspects of biomedical engineering applications lend themselves well to experimentation that can be done by high school students. This paper describes two experiments done during a six-week summer internship program in which two high school students used electrodes, circuit boards, and computers to mimic a sophisticated heart monitor and also to control a robotic car. Our experience suggests that simple illustrations of complex instrumentation can be effective in introducing adolescents to the biomedical engineering field.

Numerical Methodology for Coupled Time-Accurate Simulations of Primary and Secondary Flowpaths in Gas Turbines

NASA Technical Reports Server (NTRS)

Przekwas, A. J.; Athavale, M. M.; Hendricks, R. C.; Steinetz, B. M.

2006-01-01

Detailed information of the flow-fields in the secondary flowpaths and their interaction with the primary flows in gas turbine engines is necessary for successful designs with optimized secondary flow streams. Present work is focused on the development of a simulation methodology for coupled time-accurate solutions of the two flowpaths. The secondary flowstream is treated using SCISEAL, an unstructured adaptive Cartesian grid code developed for secondary flows and seals, while the mainpath flow is solved using TURBO, a density based code with capability of resolving rotor-stator interaction in multi-stage machines. An interface is being tested that links the two codes at the rim seal to allow data exchange between the two codes for parallel, coupled execution. A description of the coupling methodology and the current status of the interface development is presented. Representative steady-state solutions of the secondary flow in the UTRC HP Rig disc cavity are also presented.

Recommendation on Transition from Primary/Secondary Radar to Secondary- Only Radar Capability

DTIC Science & Technology

1994-10-01

Radar Beacon Performance Monitor RCIU Remote Control Interface Unit RCL Remote Communications Link R E&D Research, Engineering and Development RML Radar...rate. 3.1.2.5 Maintenance The current LRRs have limited remote maintenance monitoring (RMM) capabilities via the Remote Control Interface Unit ( RCIU ...1, -2 and FPS-20 radars required an upgrade of some of the radar subsystems, namely the RCIU to respond as an RMS and the CD to interface with radar

Electronic Biomedical Literature Search for Budding Researcher

PubMed Central

Thakre, Subhash B.; Thakre S, Sushama S.; Thakre, Amol D.

2013-01-01

Search for specific and well defined literature related to subject of interest is the foremost step in research. When we are familiar with topic or subject then we can frame appropriate research question. Appropriate research question is the basis for study objectives and hypothesis. The Internet provides a quick access to an overabundance of the medical literature, in the form of primary, secondary and tertiary literature. It is accessible through journals, databases, dictionaries, textbooks, indexes, and e-journals, thereby allowing access to more varied, individualised, and systematic educational opportunities. Web search engine is a tool designed to search for information on the World Wide Web, which may be in the form of web pages, images, information, and other types of files. Search engines for internet-based search of medical literature include Google, Google scholar, Scirus, Yahoo search engine, etc., and databases include MEDLINE, PubMed, MEDLARS, etc. Several web-libraries (National library Medicine, Cochrane, Web of Science, Medical matrix, Emory libraries) have been developed as meta-sites, providing useful links to health resources globally. A researcher must keep in mind the strengths and limitations of a particular search engine/database while searching for a particular type of data. Knowledge about types of literature, levels of evidence, and detail about features of search engine as available, user interface, ease of access, reputable content, and period of time covered allow their optimal use and maximal utility in the field of medicine. Literature search is a dynamic and interactive process; there is no one way to conduct a search and there are many variables involved. It is suggested that a systematic search of literature that uses available electronic resource effectively, is more likely to produce quality research. PMID:24179937

Electronic biomedical literature search for budding researcher.

PubMed

Thakre, Subhash B; Thakre S, Sushama S; Thakre, Amol D

2013-09-01

Search for specific and well defined literature related to subject of interest is the foremost step in research. When we are familiar with topic or subject then we can frame appropriate research question. Appropriate research question is the basis for study objectives and hypothesis. The Internet provides a quick access to an overabundance of the medical literature, in the form of primary, secondary and tertiary literature. It is accessible through journals, databases, dictionaries, textbooks, indexes, and e-journals, thereby allowing access to more varied, individualised, and systematic educational opportunities. Web search engine is a tool designed to search for information on the World Wide Web, which may be in the form of web pages, images, information, and other types of files. Search engines for internet-based search of medical literature include Google, Google scholar, Scirus, Yahoo search engine, etc., and databases include MEDLINE, PubMed, MEDLARS, etc. Several web-libraries (National library Medicine, Cochrane, Web of Science, Medical matrix, Emory libraries) have been developed as meta-sites, providing useful links to health resources globally. A researcher must keep in mind the strengths and limitations of a particular search engine/database while searching for a particular type of data. Knowledge about types of literature, levels of evidence, and detail about features of search engine as available, user interface, ease of access, reputable content, and period of time covered allow their optimal use and maximal utility in the field of medicine. Literature search is a dynamic and interactive process; there is no one way to conduct a search and there are many variables involved. It is suggested that a systematic search of literature that uses available electronic resource effectively, is more likely to produce quality research.

Safety through Education and Training.

ERIC Educational Resources Information Center

Thorburn, S.

1990-01-01

Addresses the need for safety education as a continuous process through elementary and secondary phases of education in the context of human risk within modern society. Discusses the teaching of safety subjects in civil engineering curriculum. (YP)

Enhancing Science, Technology, Engineering, and Mathematics Education Act of 2009

THOMAS, 111th Congress

Rep. Honda, Michael M. [D-CA-15

2009-06-04

House - 07/23/2009 Referred to the Subcommittee on Early Childhood, Elementary, and Secondary Education. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

A surface treatment management system.

DOT National Transportation Integrated Search

1988-01-01

A brief survey presented in this report illustrates the variability in management practices for the surface treatment of secondary roads across the country. In Virginia, an informal process that uses the experience of field engineers working within b...

46 CFR 38.05-1 - Design and construction of vessels-general-TB/ALL.

Code of Federal Regulations, 2010 CFR

2010-10-01

... system shall satisfy the requirements for toughness specified in subchapter F (Marine Engineering) of... secondary barrier is required, the material of that barrier and of contiguous hull structure shall have...

Affective Strategies at the Secondary Level.

ERIC Educational Resources Information Center

Williamson, Ann Pollard

Affective teaching is particularly important at the secondary level when the student is facing the problems of adolescence (physical change, sex, social development, identity, values, and alienation). One of the most commonly accepted strategies at the secondary level is that of improving self-concept through the study of literature. Since an…

Response to Intervention with Secondary School Students with Reading Difficulties

ERIC Educational Resources Information Center

Vaughn, Sharon; Fletcher, Jack M.

2012-01-01

The authors summarize evidence from a multiyear study with secondary students with reading difficulties on (a) the potential efficacy of primary-level (Tier 1), secondary-level (Tier 2), and tertiary-level (Tier 3) interventions in remediating reading difficulties with middle school students, (b) the likelihood of resolving reading disabilities…

Establishing a STEM Pipeline: Trends in Male and Female Enrollment and Performance in Higher Level Secondary STEM Courses

ERIC Educational Resources Information Center

Bergeron, Liz; Gordon, Melissa

2017-01-01

The purpose of this study was to understand enrollment and performance differences between male and females in higher level secondary STEM courses. This study analyzes performance and enrollment of 355,688 secondary students in higher level STEM courses. This research also enabled an exploration of country level differences. The enrollment…

Source localization of turboshaft engine broadband noise using a three-sensor coherence method

NASA Astrophysics Data System (ADS)

Blacodon, Daniel; Lewy, Serge

2015-03-01

Turboshaft engines can become the main source of helicopter noise at takeoff. Inlet radiation mainly comes from the compressor tones, but aft radiation is more intricate: turbine tones usually are above the audible frequency range and do not contribute to the weighted sound levels; jet is secondary and radiates low noise levels. A broadband component is the most annoying but its sources are not well known (it is called internal or core noise). Present study was made in the framework of the European project TEENI (Turboshaft Engine Exhaust Noise Identification). Its main objective was to localize the broadband sources in order to better reduce them. Several diagnostic techniques were implemented by the various TEENI partners. As regards ONERA, a first attempt at separating sources was made in the past with Turbomeca using a three-signal coherence method (TSM) to reject background non-acoustic noise. The main difficulty when using TSM is the assessment of the frequency range where the results are valid. This drawback has been circumvented in the TSM implemented in TEENI. Measurements were made on a highly instrumented Ardiden turboshaft engine in the Turbomeca open-air test bench. Two engine powers (approach and takeoff) were selected to apply TSM. Two internal pressure probes were located in various cross-sections, either behind the combustion chamber (CC), the high-pressure turbine (HPT), the free-turbine first stage (TL), or in four nozzle sections. The third transducer was a far-field microphone located around the maximum of radiation, at 120° from the intake centerline. The key result is that coherence increases from CC to HPT and TL, then decreases in the nozzle up to the exit. Pressure fluctuations from HPT and TL are very coherent with the far-field acoustic spectra up to 700 Hz. They are thus the main acoustic source and can be attributed to indirect combustion noise (accuracy decreases above 700 Hz because coherence is lower, but far-field sound spectra also are much lower above 700 Hz).

Creating metabolic demand as an engineering strategy in Pseudomonas putida - Rhamnolipid synthesis as an example.

PubMed

Tiso, Till; Sabelhaus, Petra; Behrens, Beate; Wittgens, Andreas; Rosenau, Frank; Hayen, Heiko; Blank, Lars Mathias

2016-12-01

Metabolic engineering of microbial cell factories for the production of heterologous secondary metabolites implicitly relies on the intensification of intracellular flux directed toward the product of choice. Apart from reactions following peripheral pathways, enzymes of the central carbon metabolism are usually targeted for the enhancement of precursor supply. In Pseudomonas putida , a Gram-negative soil bacterium, central carbon metabolism, i.e., the reactions required for the synthesis of all 12 biomass precursors, was shown to be regulated at the metabolic level and not at the transcriptional level. The bacterium's central carbon metabolism appears to be driven by demand to react rapidly to ever-changing environmental conditions. In contrast, peripheral pathways that are only required for growth under certain conditions are regulated transcriptionally. In this work, we show that this regulation regime can be exploited for metabolic engineering. We tested this driven-by-demand metabolic engineering strategy using rhamnolipid production as an example. Rhamnolipid synthesis relies on two pathways, i.e., fatty acid de novo synthesis and the rhamnose pathway, providing the required precursors hydroxyalkanoyloxy-alkanoic acid (HAA) and activated (dTDP-)rhamnose, respectively. In contrast to single-pathway molecules, rhamnolipid synthesis causes demand for two central carbon metabolism intermediates, i.e., acetyl-CoA for HAA and glucose-6-phosphate for rhamnose synthesis. Following the above-outlined strategy of driven by demand, a synthetic promoter library was developed to identify the optimal expression of the two essential genes ( rhlAB ) for rhamnolipid synthesis. The best rhamnolipid-synthesizing strain had a yield of 40% rhamnolipids on sugar [Cmol RL /Cmol Glc ], which is approximately 55% of the theoretical yield. The rate of rhamnolipid synthesis of this strain was also high. Compared to an exponentially growing wild type, the rhamnose pathway increased its flux by 300%, whereas the flux through de novo fatty acid synthesis increased by 50%. We show that the central carbon metabolism of P. putida is capable of meeting the metabolic demand generated by engineering transcription in peripheral pathways, thereby enabling a significant rerouting of carbon flux toward the product of interest, in this case, rhamnolipids of industrial interest.

Enhanced formation of aromatic amino acids increases fragrance without affecting flower longevity or pigmentation in Petunia × hybrida.

PubMed

Oliva, Moran; Ovadia, Rinat; Perl, Avichai; Bar, Einat; Lewinsohn, Efraim; Galili, Gad; Oren-Shamir, Michal

2015-01-01

Purple Petunia × hybrida V26 plants accumulate fragrant benzenoid-phenylpropanoid molecules and anthocyanin pigments in their petals. These specialized metabolites are synthesized mainly from the aromatic amino acids phenylalanine. Here, we studied the profile of secondary metabolites of petunia plants, expressing a feedback-insensitive bacterial form of 3-deoxy-di-arabino-heptulosonate 7-phosphate synthase enzyme (AroG*) of the shikimate pathway, as a tool to stimulate the conversion of primary to secondary metabolism via the aromatic amino acids. We focused on specialized metabolites contributing to flower showy traits. The presence of AroG* protein led to increased aromatic amino acid levels in the leaves and high phenylalanine levels in the petals. In addition, the AroG* petals accumulated significantly higher levels of fragrant benzenoid-phenylpropanoid volatiles, without affecting the flowers' lifetime. In contrast, AroG* abundance had no effect on flavonoids and anthocyanins levels. The metabolic profile of all five AroG* lines was comparable, even though two lines produced the transgene in the leaves, but not in the petals. This implies that phenylalanine produced in leaves can be transported through the stem to the flowers and serve as a precursor for formation of fragrant metabolites. Dipping cut petunia stems in labelled phenylalanine solution resulted in production of labelled fragrant volatiles in the flowers. This study emphasizes further the potential of this metabolic engineering approach to stimulate the production of specialized metabolites and enhance the quality of various plant organs. Furthermore, transformation of vegetative tissues with AroG* is sufficient for induced production of specialized metabolites in organs such as the flowers. © 2014 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

Turbomachine Sealing and Secondary Flows - Part 3. Part 3; Review of Power-Stream Support, Unsteady Flow Systems, Seal and Disk Cavity Flows, Engine Externals, and Life and Reliability Issues

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Steinetz, B. M.; Zaretsky, E. V.; Athavale, M. M.; Przekwas, A. J.

2004-01-01

The issues and components supporting the engine power stream are reviewed. It is essential that companies pay close attention to engine sealing issues, particularly on the high-pressure spool or high-pressure pumps. Small changes in these systems are reflected throughout the entire engine. Although cavity, platform, and tip sealing are complex and have a significant effect on component and engine performance, computational tools (e.g., NASA-developed INDSEAL, SCISEAL, and ADPAC) are available to help guide the designer and the experimenter. Gas turbine engine and rocket engine externals must all function efficiently with a high degree of reliability in order for the engine to run but often receive little attention until they malfunction. Within the open literature statistically significant data for critical engine components are virtually nonexistent; the classic approach is deterministic. Studies show that variations with loading can have a significant effect on component performance and life. Without validation data they are just studies. These variations and deficits in statistical databases require immediate attention.

ZmNST3 and ZmNST4 are master switches for secondary wall deposition in maize (Zea mays L.).

PubMed

Xiao, Wenhan; Yang, Yue; Yu, Jingjuan

2018-01-01

Secondary walls are the most abundant biomass produced by plants, and they consist mainly of lignin, cellulose and hemicellulose. Understanding how secondary wall biosynthesis is regulated could potentially provide genetic tools for engineering biomass components, especially in maize and Sorghum bicolor. Although many works have focused on secondary wall biosynthesis in dicotyledons, little has been reported for these monocotyledons. In this study, we cloned two NAC transcriptional factor genes, ZmNST3 and ZmNST4, and analyzed their functions in maize secondary wall formation process. ZmNST3 and ZmNST4 were expressed specifically in secondary wall-forming cells, expression of ZmNST3/4 can restore the pendent phenotype of Arabidopsis nst1nst3 double mutant. ZmNST3/4-overexpressing Arabidopsis and maize displayed a thickened secondary wall in the stem, and knockdown maize showed defective secondary wall deposition. ZmNST3/4 could regulate the expression of ZmMYB109/128/149. Our results revealed that ZmNST3/4 are master switches of the maize secondary wall biosynthesis process and provides new evidence that the secondary wall regulatory pathway is conserved in different plant species. Copyright © 2017. Published by Elsevier B.V.

Navier-Stokes analysis and experimental data comparison of compressible flow within ducts

NASA Technical Reports Server (NTRS)

Harloff, G. J.; Reichert, B. A.; Sirbaugh, J. R.; Wellborn, S. R.

1992-01-01

Many aircraft employ ducts with centerline curvature or changing cross-sectional shape to join the engine with inlet and exhaust components. S-ducts convey air to the engine compressor from the intake and often decelerate the flow to achieve an acceptable Mach number at the engine compressor by increasing the cross-sectional area downstream. Circular-to-rectangular transition ducts are used on aircraft with rectangular exhaust nozzles to connect the engine and nozzle. To achieve maximum engine performance, the ducts should minimize flow total pressure loss and total pressure distortion at the duct exit. Changes in the curvature of the duct centerline or the duct cross-sectional shape give rise to streamline curvature which causes cross stream pressure gradients. Secondary flows can be caused by deflection of the transverse vorticity component of the boundary layer. This vortex tilting results in counter-rotating vortices. Additionally, the adverse streamwise pressure gradient caused by increasing cross-sectional area can lead to flow separation. Vortex pairs have been observed in the exit planes of both duct types. These vortices are due to secondary flows induced by pressure gradients resulting from streamline curvature. Regions of low total pressure are produced when the vortices convect boundary layer fluid into the main flow. The purpose of the present study is to predict the measured flow field in a diffusing S-duct and a circular-to-rectangular transition duct with a full Navier-Stokes computer program, PARC3D, and to compare the numerical predictions with new detailed experimental measurements. The work was undertaken to extend previous studies and to provide additional CFD validation data needed to help model flows with strong secondary flow and boundary layer separation. The S-duct computation extends the study of Smith et al, and Harloff et al, which concluded that the computation might be improved by using a finer grid and more advanced turbulence models. The present study compares results for both the Baldwin-Lomas and k-epsilon turbulence models and is conducted with a refined grid. For the transition duct, two inlet conditions were considered, the first with straight flow and the second with swirling flow. The first case permits examination of the effects of the geometric transition on the flow field, while the second case includes the rotational flow effect characteristic of a gas turbine engine.

Intramural Programming for Elementary, Junior Secondary, and Senior Secondary Schools. A Practical Approach.

ERIC Educational Resources Information Center

Watts, Gayle E.; Korchinsky, Nestor N.

A justification for the offering of intramural sports is offered, and an introduction to methods for establishing such programs at the elementary, junior secondary, and senior secondary school levels is presented. General information on intramural programing at each level includes discussion of questions on commitment, financing, liability,…

Identification of GATC- and CCGG- recognizing Type II REases and their putative specificity-determining positions using Scan2S—a novel motif scan algorithm with optional secondary structure constraints

PubMed Central

Niv, Masha Y.; Skrabanek, Lucy; Roberts, Richard J.; Scheraga, Harold A.; Weinstein, Harel

2008-01-01

Restriction endonucleases (REases) are DNA-cleaving enzymes that have become indispensable tools in molecular biology. Type II REases are highly divergent in sequence despite their common structural core, function and, in some cases, common specificities towards DNA sequences. This makes it difficult to identify and classify them functionally based on sequence, and has hampered the efforts of specificity-engineering. Here, we define novel REase sequence motifs, which extend beyond the PD-(D/E)XK hallmark, and incorporate secondary structure information. The automated search using these motifs is carried out with a newly developed fast regular expression matching algorithm that accommodates long patterns with optional secondary structure constraints. Using this new tool, named Scan2S, motifs derived from REases with specificity towards GATC- and CGGG-containing DNA sequences successfully identify REases of the same specificity. Notably, some of these sequences are not identified by standard sequence detection tools. The new motifs highlight potential specificity-determining positions that do not fully overlap for the GATC- and the CCGG-recognizing REases and are candidates for specificity re-engineering. PMID:17972284

Identification of GATC- and CCGG-recognizing Type II REases and their putative specificity-determining positions using Scan2S--a novel motif scan algorithm with optional secondary structure constraints.

PubMed

Niv, Masha Y; Skrabanek, Lucy; Roberts, Richard J; Scheraga, Harold A; Weinstein, Harel

2008-05-01

Restriction endonucleases (REases) are DNA-cleaving enzymes that have become indispensable tools in molecular biology. Type II REases are highly divergent in sequence despite their common structural core, function and, in some cases, common specificities towards DNA sequences. This makes it difficult to identify and classify them functionally based on sequence, and has hampered the efforts of specificity-engineering. Here, we define novel REase sequence motifs, which extend beyond the PD-(D/E)XK hallmark, and incorporate secondary structure information. The automated search using these motifs is carried out with a newly developed fast regular expression matching algorithm that accommodates long patterns with optional secondary structure constraints. Using this new tool, named Scan2S, motifs derived from REases with specificity towards GATC- and CGGG-containing DNA sequences successfully identify REases of the same specificity. Notably, some of these sequences are not identified by standard sequence detection tools. The new motifs highlight potential specificity-determining positions that do not fully overlap for the GATC- and the CCGG-recognizing REases and are candidates for specificity re-engineering.

Comparison between Emotional Intelligence and Aggression among Student Teachers at Secondary Level

ERIC Educational Resources Information Center

Jaleel, Sajna; Verghis, Alie Molly

2017-01-01

The study explored the relationship between emotional intelligence and aggression among teacher trainees at secondary level. The hypothesis formulated for the study was, there is no significant relationship between Emotional Intelligence and aggression of teacher trainees at secondary level. The method adopted for the study was descriptive survey,…

Multi-Mission Power Analysis Tool (MMPAT) Version 3

NASA Technical Reports Server (NTRS)

Wood, Eric G.; Chang, George W.; Chen, Fannie C.

2012-01-01

The Multi-Mission Power Analysis Tool (MMPAT) simulates a spacecraft power subsystem including the power source (solar array and/or radioisotope thermoelectric generator), bus-voltage control, secondary battery (lithium-ion or nickel-hydrogen), thermostatic heaters, and power-consuming equipment. It handles multiple mission types including heliocentric orbiters, planetary orbiters, and surface operations. Being parametrically driven along with its user-programmable features can reduce or even eliminate any need for software modifications when configuring it for a particular spacecraft. It provides multiple levels of fidelity, thereby fulfilling the vast majority of a project s power simulation needs throughout the lifecycle. It can operate in a stand-alone mode with a graphical user interface, in batch mode, or as a library linked with other tools. This software can simulate all major aspects of a spacecraft power subsystem. It is parametrically driven to reduce or eliminate the need for a programmer. Added flexibility is provided through user-designed state models and table-driven parameters. MMPAT is designed to be used by a variety of users, such as power subsystem engineers for sizing power subsystem components; mission planners for adjusting mission scenarios using power profiles generated by the model; system engineers for performing system- level trade studies using the results of the model during the early design phases of a spacecraft; and operations personnel for high-fidelity modeling of the essential power aspect of the planning picture.

Free-field propagation of high intensity noise

NASA Technical Reports Server (NTRS)

Welz, Joseph P.; Mcdaniel, Oliver H.

1990-01-01

Observed spectral data from supersonic jet aircraft are known to contain much more high frequency energy than can be explained by linear acoustic propagation theory. It is believed that the high frequency energy is an effect of nonlinear distortion due to the extremely high acoustic levels generated by the jet engines. The objective, to measure acoustic waveform distortion for spherically diverging high intensity noise, was reached by using an electropneumatic acoustic source capable of generating sound pressure levels in the range of 140 to 160 decibels (re 20 micro Pa). The noise spectrum was shaped to represent the spectra generated by jet engines. Two microphones were used to capture the acoustic pressure waveform at different points along the propagation path in order to provide a direct measure of the waveform distortion as well as spectral distortion. A secondary objective was to determine that the observed distortion is an acoustic effect. To do this an existing computer prediction code that deals with nonlinear acoustic propagation was used on data representative of the measured data. The results clearly demonstrate that high intensity jet noise does shift the energy in the spectrum to the higher frequencies along the propagation path. In addition, the data from the computer model are in good agreement with the measurements, thus demonstrating that the waveform distortion can be accounted for with nonlinear acoustic theory.

Structure and Mechanics

NASA Technical Reports Server (NTRS)

Sanger, George

1991-01-01

Artemis is a Common Lunar Lander (CLL) design for the Space Exploration Initiative (SEI). Structure factors for the CLL's primary and secondary structures are listed in tabular form. Additionally, engineering drawings of various systems, including the propulsion and landing systems, are presented.

Low-cost rural surface alternatives : literature review and recommendations.

DOT National Transportation Integrated Search

2013-12-01

Freezing and thawing action induces damage to unbound gravel roads in Iowa resulting in maintenance costs for secondary road departments. Some approaches currently used by County Engineers to deal with this problem include temporarily spreading rock ...

Resources in Technology.

ERIC Educational Resources Information Center

McCrory, David L.; Maughan, George R.

This document--intended for secondary school and college students--contains technology education instructional units on engines and power, energy conversion, energy futures, energy sources, communication and society, energy and power in communication, communication systems, microelectronics in communication, transportation in society, energy and…

Strain engineering in epitaxial Ge1- x Sn x : a path towards low-defect and high Sn-content layers

NASA Astrophysics Data System (ADS)

Margetis, Joe; Yu, Shui-Qing; Bhargava, Nupur; Li, Baohua; Du, Wei; Tolle, John

2017-12-01

The plastic strain relaxation of CVD-grown Ge1-x Sn x layers was investigated in x = 0.09 samples with thicknesses of 152, 180, 257, 570, and 865 nm. X-ray diffraction-reciprocal space mapping was used to determine the strain, composition, and the nature of defects in each layer. Secondary ion mass spectrometry was used to examine the evolution of the compositional profile. These results indicate that growth beyond the critical thickness results in the spontaneous formation of a relaxed and highly defective 9% Sn layer followed by a low defect 12% Sn secondary layer. We find that this growth method can be used to engineer thick, strain-relaxed, and low defect density layers. Furthermore we utilize this strain-dependent Sn incorporation behavior to achieve Sn compositions of 17.5%. Photoluminesence of these layers produces light emission at 3.1 μm.

Genetically engineering Synechocystis sp. Pasteur Culture Collection 6803 for the sustainable production of the plant secondary metabolite p-coumaric acid.

PubMed

Xue, Yong; Zhang, Yan; Cheng, Dan; Daddy, Soumana; He, Qingfang

2014-07-01

p-Coumaric acid is the precursor of phenylpropanoids, which are plant secondary metabolites that are beneficial to human health. Tyrosine ammonia lyase catalyzes the production of p-coumaric acid from tyrosine. Because of their photosynthetic ability and biosynthetic versatility, cyanobacteria are promising candidates for the production of certain plant metabolites, including phenylpropanoids. Here, we produced p-coumaric acid in a strain of transgenic cyanobacterium Synechocystis sp. Pasteur Culture Collection 6803 (hereafter Synechocystis 6803). Whereas a strain of Synechocystis 6803 genetically engineered to express sam8, a tyrosine ammonia lyase gene from the actinomycete Saccharothrix espanaensis, accumulated little or no p-coumaric acid, a strain that both expressed sam8 and lacked slr1573, a native hypothetical gene shown here to encode a laccase that oxidizes polyphenols, produced ∼82.6 mg/L p-coumaric acid, which was readily purified from the growth medium.

Genetically engineering Synechocystis sp. Pasteur Culture Collection 6803 for the sustainable production of the plant secondary metabolite p-coumaric acid

PubMed Central

Xue, Yong; Zhang, Yan; Cheng, Dan; Daddy, Soumana; He, Qingfang

2014-01-01

p-Coumaric acid is the precursor of phenylpropanoids, which are plant secondary metabolites that are beneficial to human health. Tyrosine ammonia lyase catalyzes the production of p-coumaric acid from tyrosine. Because of their photosynthetic ability and biosynthetic versatility, cyanobacteria are promising candidates for the production of certain plant metabolites, including phenylpropanoids. Here, we produced p-coumaric acid in a strain of transgenic cyanobacterium Synechocystis sp. Pasteur Culture Collection 6803 (hereafter Synechocystis 6803). Whereas a strain of Synechocystis 6803 genetically engineered to express sam8, a tyrosine ammonia lyase gene from the actinomycete Saccharothrix espanaensis, accumulated little or no p-coumaric acid, a strain that both expressed sam8 and lacked slr1573, a native hypothetical gene shown here to encode a laccase that oxidizes polyphenols, produced ∼82.6 mg/L p-coumaric acid, which was readily purified from the growth medium. PMID:24927550

Resources for Teachers. "Turning Ideas Into Reality: The Executive Branch Fosters Engineering Excellence." An Institute for Pre-College Science and Social Studies Teachers (West Hartford, Connecticut, February 18-19, 24-26, 1989). Revised.

ERIC Educational Resources Information Center

Pierce, Preston E., Comp.

A compilation of resources is provided for those interested in examining action taken by the executive branch of the federal government to foster scientific and engineering excellence in the United States in the nineteenth century. The resources are intended for use by pre-college secondary science and social studies teachers. Each of the…

An Update of Engine System Research at the Army Propulsion Directorate

DTIC Science & Technology

1990-01-01

6.1) pro- grams. Brush seals , illustrated in figure 14, offer great potential for reduc- ing secondary flow leakages and are inherently self...incorporate brush seals into the build of one of our workhorse engines in the early 1990’s as a replacement for shaft carbon seals , inner air labyrinth seals ...to steam and increasing its cooling capacity (ref. 12). The idea was conceived in-house and, following feasibility studies and fundamental heat

New Standard Weir Design for Dredged Material Management Area, Jacksonville District

DTIC Science & Technology

2014-08-01

dock access, Bartram Island Cell B2, Jacksonville, Florida. Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 ERDC/TN DOTS-14-01 August 2014 2 US Army Corps of Engineers • Engineer Research...and through the riser stack of weir boards. This requires secondary sealing measures in the form of plastic sheeting, geotextiles, and/or burlap

Using Six Sigma to Accelerate the Adoption of CMMI for Optimal Results

DTIC Science & Technology

2004-10-01

Findings Path forward © 2004 by Carnegie Mellon University Version 1.0 page 5 Carnegie Mellon S oftware Engineer ing Inst itute Software & IT Best...Related Technology ( COBIT ) Secondary priority • architecture best practices and Design for Six Sigma Primary audiences • Software Engineering Process Groups...itute Context of Findings While our focus was on CMMI, ITIL, and COBIT , we gathered information on other technologies “in play.” • The list included

Engine systems analysis results of the Space Shuttle Main Engine redesigned powerhead initial engine level testing

NASA Technical Reports Server (NTRS)

Sander, Erik J.; Gosdin, Dennis R.

1992-01-01

Engineers regularly analyze SSME ground test and flight data with respect to engine systems performance. Recently, a redesigned SSME powerhead was introduced to engine-level testing in part to increase engine operational margins through optimization of the engine internal environment. This paper presents an overview of the MSFC personnel engine systems analysis results and conclusions reached from initial engine level testing of the redesigned powerhead, and further redesigns incorporated to eliminate accelerated main injector baffle and main combustion chamber hot gas wall degradation. The conclusions are drawn from instrumented engine ground test data and hardware integrity analysis reports and address initial engine test results with respect to the apparent design change effects on engine system and component operation.

New secondary batteries utilizing electronically conductive polymer cathodes

NASA Technical Reports Server (NTRS)

Martin, Charles R.; White, Ralph E.

1989-01-01

The objectives of this project are to optimize the transport rates in electronically conductive polypyrrole films by controlling the morphology of the film and to assess the utility of these films as cathodes in a lithium/polypyrrole secondary battery. During this research period, progress has been made in improving the charge transport rate of the supermolecular-engineered polypyrrole electrode by eliminating the polypyrrole baselayer that hampered earlier work. Also, the fibril density of the polypyrrole electrode was increased, providing more electroactive sites per unit area.

Industrial waste treatment and application in rubber production

NASA Astrophysics Data System (ADS)

Pugacheva, I. N.; Popova, L. V.; Repin, P. S.; Molokanova, L. V.

2018-03-01

The paper provides for the relevance of various industrial waste treatment and application, as well as their secondary commercialization. It considers treatment of secondary polymer materials turning to additives applied in rubber production, in particular, in production of conveyor and V-type belts used in mechanical engineering. It is found that oligomers obtained from petroleum by-products can be used as an impregnating compound for fiber materials. Such adhesive treatment prior to introduction of impregnating compounds into elastomeric materials improves adhesion and complements performance of obtained composites.

CFD Techniques for Propulsion Applications Panel Symposium (77th), Held in San Antonio, Texas on 27-31 May 1991 (Les Techniques de l’Aerodynamique Numerique pour les Applications aux Propulseurs)

DTIC Science & Technology

1992-02-01

CONCLUDING REMARKS secondary flow pattern. Probably both factors are influential. Unfortunately The present study has examined the the secondary...Panels which are compesed of experts appointed - by the National Delegates, the Consultant and Exchange Programme and the Aerospace Applications Studies ...CP 352. September 1983 /Combustion Problems in Turbine Engines AGARD CP 353, January 1984 (,rHazard Studies for Solid Propellant Rocket Motors AGARD CP

Experimental/Analytical Characterization of the RBCC Rocket-Ejector Mode

NASA Technical Reports Server (NTRS)

Ruf, J. H.; Lehman, M.; Pal, S.; Santoro, R. J.

2000-01-01

The experimental/analytical research work described here addresses the rocket-ejector mode (Mach 0-2 operational range) of the RBCC engine. The experimental phase of the program includes studying the mixing and combustion characteristics of the rocket-ejector system utilizing state-of-the-art diagnostic techniques. A two-dimensional variable geometry rocket-ejector system with enhanced optical access was utilized as the experimental platform. The goals of the experimental phase of the research being conducted at Penn State are to: (a) systematically increase the range of rocket-ejector understanding over a wide range of flow/geometry parameters and (b) provide a comprehensive data base for evaluating and anchoring CFD codes. Concurrent with the experimental activities, a CFD code benchmarking effort at Marshall Space Flight Center is also being used to further investigate the RBCC rocket-ejector mode. Experiments involving the single rocket based optically-accessible rocket-ejector system have been conducted for Diffusion and Afterburning (DAB) as well as Simultaneous Mixing and Combustion configurations. For the DAB configuration, air is introduced (direct-connect) or ejected (sea-level static) into a constant area mixer section with a centrally located gaseous oxygen (GO2)/gaseous hydrogen (GH2) rocket combustor. The downstream flowpath for this configuration includes a diffuser, an afterburner and a final converging nozzle. For the SMC configuration, the rocket is centrally located in a slightly divergent duct. For all tested configurations, global measurements of the axial pressure and heat transfer profiles as well as the overall engine thrust were made. Detailed measurements include major species concentration (H2 O2 N2 and H2O) profiles at various mixer locations made using Raman spectroscopy. Complementary CFD calculations of the flowfield at the experimental conditions also provide additional information on the physics of the problem. These calculations are being conducted at Marshall Space Flight Center to benchmark the FDNS code for RBCC engine operations for such configurations. The primary fluid physics of interests are the mixing and interaction of the rocket plume and secondary flow, subsequent combustion of the fuel rich rocket exhaust with the secondary flow and combustion of the injected afterburner flow. The CFD results are compared to static pressure along the RBCC duct walls, Raman Spectroscopy specie distribution data at several axial locations, net engine thrust and entrained air for the SLS cases. The CFD results compare reasonably well with the experimental results.

Characterization and 3-D modeling of Ni60Ti SMA for actuation of a variable geometry jet engine chevron

NASA Astrophysics Data System (ADS)

Hartl, Darren J.; Lagoudas, Dimitris C.

2007-04-01

This work describes the thermomechanical characterization and FEA modeling of commercial jet engine chevrons incorporating active Shape Memory Alloy (SMA) beam components. The reduction of community noise at airports generated during aircraft take-off has become a major research goal. Serrated aerodynamic devices along the trailing edge of a jet engine primary and secondary exhaust nozzle, known as chevrons, have been shown to greatly reduce jet noise by encouraging advantageous mixing of the streams. To achieve the noise reduction, the secondary exhaust nozzle chevrons are typically immersed into the fan flow which results in drag, or thrust losses during cruise. SMA materials have been applied to this problem of jet engine noise. Active chevrons, utilizing SMA components, have been developed and tested to create maximum deflection during takeoff and landing while minimizing deflection into the flow during the remainder of flight, increasing efficiency. Boeing has flight tested one Variable Geometry Chevron (VGC) system which includes active SMA beams encased in a composite structure with a complex 3-D configuration. The SMA beams, when activated, induce the necessary bending forces on the chevron structure to deflect it into the fan flow and reduce noise. The SMA composition chosen for the fabrication of these beams is a Ni60Ti40 (wt%) alloy. In order to calibrate the material parameters of the constitutive SMA model, various thermomechanical experiments are performed on trained (stabilized) standard SMA tensile specimens. Primary among these tests are thermal cycles at various constant stress levels. Material properties for the shape memory alloy components are derived from this tensile experimentation. Using this data, a 3-D FEA implementation of a phenomenological SMA model is calibrated and used to analyze the response of the chevron. The primary focus of this work is the full 3-D modeling of the active chevron system behavior by considering the SMA beams as fastened to the elastic chevron structure. Experimental and numerical results are compared. Discussion is focused on actuation properties such as tip deflection and chevron bending profile. The model proves to be an accurate tool for predicting the mechanical response of such a system subject to defined thermal inputs.

Engineers Work on the James Webb Space Telescope

NASA Image and Video Library

2017-12-08

Engineers at Ball Aerospace test the Wavefront Sensing and Control testbed to ensure that the 18 primary mirror segments and one secondary mirror on JWST work as one. The test is performed on a 1/6 scale model of the JWST mirrors. Credit: NASA/Northrop Grumman/Ball Aerospace To read more about the James Webb Space Telescope go to: www.nasa.gov/topics/technology/features/partnerships.html NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

Design considerations for a Space Shuttle Main Engine turbine blade made of single crystal material

NASA Technical Reports Server (NTRS)

Abdul-Aziz, A.; August, R.; Nagpal, V.

1993-01-01

Nonlinear finite-element structural analyses were performed on the first stage high-pressure fuel turbopump blade of the Space Shuttle Main Engine. The analyses examined the structural response and the dynamic characteristics at typical operating conditions. Single crystal material PWA-1480 was considered for the analyses. Structural response and the blade natural frequencies with respect to the crystal orientation were investigated. The analyses were conducted based on typical test stand engine cycle. Influence of combined thermal, aerodynamic, and centrifugal loadings was considered. Results obtained showed that the single crystal secondary orientation effects on the maximum principal stresses are not highly significant.

Effect of B20 and Low Aromatic Diesel on Transit Bus NOx Emissions Over Driving Cycles with a Range of Kinetic Intensity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lammert, M. P.; McCormick, R. L.; Sindler, P.

2012-10-01

Oxides of nitrogen (NOx) emissions for transit buses for up to five different fuels and three standard transit duty cycles were compared to establish whether there is a real-world biodiesel NOx increase for transit bus duty cycles and engine calibrations. Six buses representing the majority of the current national transit fleet and including hybrid and selective catalyst reduction systems were tested on a heavy-duty chassis dynamometer with certification diesel, certification B20 blend, low aromatic (California Air Resources Board) diesel, low aromatic B20 blend, and B100 fuels over the Manhattan, Orange County and UDDS test cycles. Engine emissions certification level hadmore » the dominant effect on NOx; kinetic intensity was the secondary driving factor. The biodiesel effect on NOx emissions was not statistically significant for most buses and duty cycles for blends with certification diesel, except for a 2008 model year bus. CARB fuel had many more instances of a statistically significant effect of reducing NOx. SCR systems proved effective at reducing NOx to near the detection limit on all duty cycles and fuels, including B100. While offering a fuel economy benefit, a hybrid system significantly increased NOx emissions over a same year bus with a conventional drivetrain and the same engine.« less

Developing Skills for Employability at the Secondary Level: Effective Models for Asia

ERIC Educational Resources Information Center

Jayaram, Shubha; Engmann, Michelle

2014-01-01

Globally, enormous gains have been made towards the goal of universal primary education, leading to increased demands for secondary education. Consequently, more youth and young adults are now entering the formal and informal labour markets from the secondary level, which makes it important to ensure that secondary schools teach skills relevant to…

Secondary School Mathematics Teachers' Knowledge Levels and Use of History of Mathematics

ERIC Educational Resources Information Center

Bütüner, Suphi Önder

2018-01-01

This study describes secondary school mathematics teachers' use of history of mathematics in their classes and their knowledge levels in this field. The study population included a total of 58 secondary school mathematics teachers working at the secondary schools located in Yozgat city center, and the sample included 32 mathematics teachers from…

An Approach to a One-School-Year Technical/Occupational Program Articulation between the Secondary and Post-Secondary Levels.

ERIC Educational Resources Information Center

Emerson, Nancy H.

An articulation effort between secondary and postsecondary occupational education is described in this report as conducted by the Dallas County Community College District. After an introduction to the articulation project emphasizes the original goal of developing material necessary to award postsecondary credit for mastery at the secondary level,…

Effect of Crystal Orientation on Fatigue Failure of Single Crystal Nickel Base Turbine Blade Superalloys

NASA Technical Reports Server (NTRS)

Arakere, Nagaraj K.; Swanson, Gregory R.

2000-01-01

High Cycle Fatigue (HCF) induced failures in aircraft gas-turbine engines is a pervasive problem affecting a wide range of components and materials. HCF is currently the primary cause of component failures in gas turbine aircraft engines. Turbine blades in high performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys. Single-crystal Nickel-base superalloys were developed to provide superior creep, stress rupture, melt resistance and thermomechanical fatigue capabilities over polycrystalline alloys previously used in the production of turbine blades and vanes. Currently the most widely used single crystal turbine blade superalloys are PWA 1480/1493 and PWA 1484. These alloys play an important role in commercial, military and space propulsion systems. PWA1493, identical to PWA1480, but with tighter chemical constituent control, is used in the NASA SSME (Space Shuttle Main Engine) alternate turbopump, a liquid hydrogen fueled rocket engine. Objectives for this paper are motivated by the need for developing failure criteria and fatigue life evaluation procedures for high temperature single crystal components, using available fatigue data and finite element modeling of turbine blades. Using the FE (finite element) stress analysis results and the fatigue life relations developed, the effect of variation of primary and secondary crystal orientations on life is determined, at critical blade locations. The most advantageous crystal orientation for a given blade design is determined. Results presented demonstrates that control of secondary and primary crystallographic orientation has the potential to optimize blade design by increasing its resistance to fatigue crack growth without adding additional weight or cost.

A preliminary design for the GMT-Consortium Large Earth Finder (G-CLEF)

NASA Astrophysics Data System (ADS)

Szentgyorgyi, Andrew; Barnes, Stuart; Bean, Jacob; Bigelow, Bruce; Bouchez, Antonin; Chun, Moo-Young; Crane, Jeffrey D.; Epps, Harland; Evans, Ian; Evans, Janet; Frebel, Anna; Furesz, Gabor; Glenday, Alex; Guzman, Dani; Hare, Tyson; Jang, Bi-Ho; Jang, Jeong-Gyun; Jeong, Ueejong; Jordan, Andres; Kim, Kang-Min; Kim, Jihun; Li, Chih-Hao; Lopez-Morales, Mercedes; McCracken, Kenneth; McLeod, Brian; Mueller, Mark; Nah, Jakyung; Norton, Timothy; Oh, Heeyoung; Oh, Jae Sok; Ordway, Mark; Park, Byeong-Gon; Park, Chan; Park, Sung-Joon; Phillips, David; Plummer, David; Podgorski, William; Rodler, Florian; Seifahrt, Andreas; Tak, Kyung-Mo; Uomoto, Alan; Van Dam, Marcos A.; Walsworth, Ronald; Yu, Young Sam; Yuk, In-Soo

2014-08-01

The GMT-Consortium Large Earth Finder (G-CLEF) is an optical-band echelle spectrograph that has been selected as the first light instrument for the Giant Magellan Telescope (GMT). G-CLEF is a general-purpose, high dispersion spectrograph that is fiber fed and capable of extremely precise radial velocity measurements. The G-CLEF Concept Design (CoD) was selected in Spring 2013. Since then, G-CLEF has undergone science requirements and instrument requirements reviews and will be the subject of a preliminary design review (PDR) in March 2015. Since CoD review (CoDR), the overall G-CLEF design has evolved significantly as we have optimized the constituent designs of the major subsystems, i.e. the fiber system, the telescope interface, the calibration system and the spectrograph itself. These modifications have been made to enhance G-CLEF's capability to address frontier science problems, as well as to respond to the evolution of the GMT itself and developments in the technical landscape. G-CLEF has been designed by applying rigorous systems engineering methodology to flow Level 1 Scientific Objectives to Level 2 Observational Requirements and thence to Level 3 and Level 4. The rigorous systems approach applied to G-CLEF establishes a well defined science requirements framework for the engineering design. By adopting this formalism, we may flexibly update and analyze the capability of G-CLEF to respond to new scientific discoveries as we move toward first light. G-CLEF will exploit numerous technological advances and features of the GMT itself to deliver an efficient, high performance instrument, e.g. exploiting the adaptive optics secondary system to increase both throughput and radial velocity measurement precision.

A CFD Study of Turbojet and Single-Throat Ramjet Ejector Interaction

NASA Technical Reports Server (NTRS)

Chang, Ing; Hunter, Louis

1996-01-01

Supersonic ejector-diffuse systems have application in driving an advanced airbreathing propulsion system, consisting of turbojet engines acting as the primary and a single throat ramjet acting as the secondary. The turbojet engines are integrated into the single throat ramjet to minimize variable geometry and eliminate redundant propulsion components. The result is a simple, lightweight system that is operable from takeoff to high Mach numbers. At this high Mach number (approximately Mach 3.0), the turbojets are turned off and the high speed ramjet/scramjet take over and drive the vehicle to Mach 6.0. The turbojet-ejector-ramjet system consists of nonafterburning turbojet engines with ducting canted at 20 degrees to supply supersonic flow (downstream of CD nozzle) to the horizontal ramjet duct at a supply total pressure and temperature. Two conditions were modelled by a 2-D full Navier Stokes code at Mach 2.0. The code modelled the Fabri choke as well as the non-Fabri non critical case, using a computational throat to supply the back pressure. The results, which primarily predict the secondary mass flow rate and the mixed conditions at the ejector exit were in reasonable agreement with the 1-D cycle code (TBCC).

Removal properties of diesel exhaust particles by a dielectric barrier discharge reactor.

PubMed

Suzuki, Ken-ichiro; Takeuchi, Naomi; Madokoro, Kazuhiko; Fushimi, Chihiro; Yao, Shuiliang; Fujioka, Yuichi; Nihei, Yoshimasa

2008-02-01

The removal properties of diesel exhaust particles (DEP) were investigated using an engine exhaust particle size spectrometer (EEPS), field emission-type scanning electron microscopy (FE-SEM) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). DEP were treated using a dielectric barrier discharge (DBD) reactor installed in the tail pipe of a diesel engine, and a model DBD reactor fed with DEP in the mixture of N(2) and O(2). When changing the experimental parameters of both the plasma conditions and the engine load conditions, we obtained characteristic information of DEP treated with plasma discharges from the particle diameter and the composition. In evaluating the model DBD reactor, it became clear that there were two types of plasma processes (reactions with active oxygen species to yield CO(2) and reactions with active nitrogen species to yield nitrogen containing compounds). Moreover, from the result of a TOF-SIMS analysis, the characteristic secondary ions, such as C(2)H(6)N(+), C(4)H(12)N(+), and C(10)H(20)N(2)(+), were strongly detected from the DEP surfaces during the plasma discharges. This indicates that the nitrogen contained hydrocarbons were generated by plasma reactions.

NASA Hardware Heads to Kennedy For Flight Preparations

NASA Image and Video Library

2018-01-24

The Orion stage adapter will be part of the first integrated flight of NASA's heavy-lift rocket, the Space Launch System, and the Orion spacecraft. The adapter, approximately 5 feet tall and 18 feet in diameter, was designed and built at NASA's Marshall Space Flight Center in Huntsville, Alabama, with advanced friction stir welding technology. It will connect the SLS interim cryogenic propulsion stage to Orion on the first flight that will help engineers check out and verify the agency's new deep-space exploration systems. Inside the adapter, engineers installed special brackets and cabling for the 13 CubeSats that will fly as secondary payloads. The Cubesats are boot-box-sized science and technology investigations that will help pave the way for future human exploration in deep space. The Orion stage adapter flight article recently finished major testing of the avionics system that will deploy the CubeSats. Technicians at NASA's Kennedy Space Center, Florida, will install the secondary payloads and engineers will examine the hardware before it is stacked on the interim cryogenic propulsion stage in the Vehicle Assembly Building prior to launch. For more information about SLS hardware, visit nasa.gov/sls.

Saccharomyces cerevisiae as a tool for mining, studying and engineering fungal polyketide synthases

PubMed Central

Bond, Carly; Tang, Yi; Li, Li

2016-01-01

Small molecule secondary metabolites produced by organisms such as plants, bacteria, and fungi form a fascinating and important group of natural products, many of which have shown promise as medicines. Fungi in particular have been important sources of natural product polyketide pharmaceuticals. While the structural complexity of these polyketides makes them interesting and useful bioactive compounds, these same features also make them difficult and expensive to prepare and scale-up using synthetic methods. Currently, nearly all commercial polyketides are prepared through fermentation or semi-synthesis. However, elucidation and engineering of polyketide pathways in the native filamentous fungi hosts are often hampered due to a lack of established genetic tools and of understanding of the regulation of fungal secondary metabolisms. Saccharomyces cerevisiae has many advantages beneficial to the study and development of polyketide pathways from filamentous fungi due to its extensive genetic toolbox and well-studied metabolism. This review highlights the benefits S. cerevisiae provides as a tool for mining, studying, and engineering fungal polyketide synthases (PKSs), as well as notable insights this versatile tool has given us into the mechanisms and products of fungal PKSs. PMID:26850128

Saccharomyces cerevisiae as a tool for mining, studying and engineering fungal polyketide synthases.

PubMed

Bond, Carly; Tang, Yi; Li, Li

2016-04-01

Small molecule secondary metabolites produced by organisms such as plants, bacteria, and fungi form a fascinating and important group of natural products, many of which have shown promise as medicines. Fungi in particular have been important sources of natural product polyketide pharmaceuticals. While the structural complexity of these polyketides makes them interesting and useful bioactive compounds, these same features also make them difficult and expensive to prepare and scale-up using synthetic methods. Currently, nearly all commercial polyketides are prepared through fermentation or semi-synthesis. However, elucidation and engineering of polyketide pathways in the native filamentous fungi hosts are often hampered due to a lack of established genetic tools and of understanding of the regulation of fungal secondary metabolisms. Saccharomyces cerevisiae has many advantages beneficial to the study and development of polyketide pathways from filamentous fungi due to its extensive genetic toolbox and well-studied metabolism. This review highlights the benefits S. cerevisiae provides as a tool for mining, studying, and engineering fungal polyketide synthases (PKSs), as well as notable insights this versatile tool has given us into the mechanisms and products of fungal PKSs. Copyright © 2016 Elsevier Inc. All rights reserved.

The environment for women in physics in Ireland

NASA Astrophysics Data System (ADS)

McLoughlin, Eilish; Fee, Sandra; McCabe, Eithne

2015-12-01

Physics is contributing strongly to the national Irish economy, with 4.5% of the Irish workforce employed in physics-based or other science, technology, engineering, and math (STEM) sectors. However, a recent national report reveals that the proportion of women working in jobs that utilize STEM skills is less than 25% of the workforce. We present data collected from the views of 1,000 female secondary school students, young women (age 18-23), secondary-school teachers and parents on what influences secondary school students' choices of subjects and in particular STEM-related subjects. In addition, benchmarking data on female student and staff ratios for the past five years is presented from all seven Irish university physics departments.

A Review of the Suppression of Secondary Electron Emission from the Electrodes of Multistage Collectors

NASA Technical Reports Server (NTRS)

Dayton, James A., Jr.

1998-01-01

A review is presented of more than 20 years of research conducted at NASA Lewis Research Center on the suppression of secondary electron emission (SEE) for the enhancement of the efficiency of vacuum electron devices with multistage depressed collectors. This paper will include a description of measurement techniques, data from measurements of SEE on a variety of materials of engineering interest and methods of surface treatment for the suppression of SEE. In the course of this work the lowest secondary electron yield ever reported was achieved for ion textured graphite, and, in a parallel line of research, the highest yield was obtained for chemical vapor deposited thin diamond films.

Self-ignition of S.I. engine model fuels: A shock tube investigation at high pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fieweger, K.; Blumenthal, R.; Adomeit, G.

1997-06-01

The self-ignition of several spark-ignition (SI) engine fuels (iso-octane, methanol, methyl tert-butyl ether and three different mixtures of iso-octane and n-heptane), mixed with air, was investigated experimentally under relevant engine conditions by the shock tube technique. Typical modes of the self-ignition process were registered cinematographically. For temperatures relevant to piston engine combustion, the self-ignition process always starts as an inhomogeneous, deflagrative mild ignition. This instant is defined by the ignition delay time, {tau}{sub defl}. The deflagration process in most cases is followed by a secondary explosion (DDT). This transition defines a second ignition delay time, {tau}{sub DDT}, which is amore » suitable approximation for the chemical ignition delay time, if the change of the thermodynamic conditions of the unburned test gas due to deflagration is taken into account. For iso-octane at p = 40 bar, a NTC (negative temperature coefficient), behavior connected with a two step (cool flame) self-ignition at low temperatures was observed. This process was very pronounced for rich and less pronounced for stoichiometric mixtures. The results of the {tau}{sub DDT} delays of the stoichiometric mixtures were shortened by the primary deflagration process in the temperature range between 800 and 1,000 K. Various mixtures of iso-octane and n-heptane were investigated. The results show a strong influence of the n-heptane fraction in the mixture, both on the ignition delay time and on the mode of self-ignition. The self-ignition of methanol and MTBE (methyl tert-butyl ether) is characterized by a very pronounced initial deflagration. For temperatures below 900 K (methanol: 800 K), no secondary explosion occurs. Taking into account the pressure increase due to deflagration, the measured delays {tau}{sub DDT} of the secondary explosion are shortened by up to one order of magnitude.« less

A comparison of personality characteristics of male and female engineering students

NASA Astrophysics Data System (ADS)

Williams, Erin Beth

The purpose of this study was to investigate differences between personality characteristics of female and male freshmen, engineering students. A secondary purpose was to ascertain whether personality characteristics of freshmen, engineering students were different from those of general collegiate students of the same sex. The Millon Index of Personality Styles (MIPS) was administered to a sample of 72 female and 86 male freshmen, engineering students at a private midwestern engineering institution. The MIPS college normative sample of 1,600 college students was used as a comparison group. A total of 24 personality characteristics were assessed in the domains of motivation aims, cognitive modes, and interpersonal behaviors. Four hypotheses, which dealt with comparisons of the engineering samples, were tested by way of discriminant analyses. Two hypotheses, which compared the engineering samples to the collegiate samples of the same sex, were tested by way of t-tests. All six hypotheses yielded significant differences across various personality variables. It was concluded that engineering students of both sexes were more similar than different in personality characteristics. It was also concluded that there were greater personality differences between freshmen male engineering students and male college students than there are between freshmen female engineering students and female college students.

Race, class and gender in engineering education: A quantitative investigation of first year enrollment

NASA Astrophysics Data System (ADS)

Phillips, Canek Moises Luna

Research explanations for the disparity across both race and gender in engineering education has typically relied on a deficit model, whereby women and people of color lack the requisite knowledge or psychological characteristics that Whites and men have to become engineers in sufficient numbers. Instead of using a deficit model approach to explain gender and race disparity, in the three studies conducted for this dissertation, I approach gender and race disparity as the result of processes of segregation linked to the historic and on-going perpetuation of systemic sources of oppression in the United States. In the first study, I investigate the relationship between the odds ratios of women and men enrolled in first year US engineering programs and institutional characteristics. To do this, I employ linear regression to study data from the American Society of Engineering Education (ASEE) and the National Center for Education Statistics (NCES) to quantify relationships between odds ratios and institutional characteristics. Results of the linear regression models showed significant relationships between the cost of universities and university selectivity and the odds ratios of women choosing engineering. I theorize how the results could be related to the operation of occupational segregation in engineering, particularly how class-based markers have been historically used by women to overcome gender-based segregation in engineering. In the second study, I examine longitudinal patterns of race, gender, and intersectional combinations of race and gender in enrollments of students in first year engineering programs across the United States (US). Using enrollment data from the American Society of Engineering Education and California Post-Secondary Education Commission, I construct measures of segregation to study how trends in the disparity of students by race could be related to increases in public school segregation nationally over the past 25 years. I found that as public school segregation levels increased nationally, underrepresentation of Black and Hispanics and overrepresentation of White and Asian students has moved further toward the extremes in first year engineering programs compared to these groups’ shares of high school enrollment. I conclude that the study of public school segregation and its effect on racial disparity needs greater attention, as well as that the investigation I conducted serves as a beginning towards pushing back on deficit model explanations of race and gender disparity in engineering. In the third study, I return to the investigation of odds ratios and institutional characteristics, constructing odds ratios using ASEE and NCES data based on the odds of enrollment in first year engineering programs between Asian, Black, and Hispanic students compared to White students. I again quantify the relationships between odds ratios and institutional characteristics using linear regression models and discuss results using theory based in the perspective of occupational segregation. In this case, results were inconclusive leading me to conclude that other variables that I did not consider, such as the segregation levels of schools that students come from before enrollment, should be considered as I develop my own future study into the topic.

24 CFR 3280.903 - General requirements for designing the structure to withstand transportation shock and vibration.

Code of Federal Regulations, 2013 CFR

2013-04-01

... manufactured home shall be designed, in terms of its structural, plumbing, mechanical and electrical systems... subsequent secondary transportation moves. (c) In place of an engineering analysis, either of the following...

24 CFR 3280.903 - General requirements for designing the structure to withstand transportation shock and vibration.

Code of Federal Regulations, 2011 CFR

2011-04-01

... manufactured home shall be designed, in terms of its structural, plumbing, mechanical and electrical systems... subsequent secondary transportation moves. (c) In place of an engineering analysis, either of the following...

24 CFR 3280.903 - General requirements for designing the structure to withstand transportation shock and vibration.

Code of Federal Regulations, 2012 CFR

2012-04-01

... manufactured home shall be designed, in terms of its structural, plumbing, mechanical and electrical systems... subsequent secondary transportation moves. (c) In place of an engineering analysis, either of the following...

24 CFR 3280.903 - General requirements for designing the structure to withstand transportation shock and vibration.

Code of Federal Regulations, 2014 CFR

2014-04-01

... manufactured home shall be designed, in terms of its structural, plumbing, mechanical and electrical systems... subsequent secondary transportation moves. (c) In place of an engineering analysis, either of the following...

Cloud Forming Potential of Aerosol from Light-duty Gasoline Direct Injection Vehicles

DOT National Transportation Integrated Search

2017-12-01

In this study, we evaluate the hygroscopicity and droplet kinetics of fresh and aged emissions from new generation gasoline direct injector engines retrofitted with a gasoline particulate filter (GPF). Furthermore, ageing and subsequent secondary aer...

Creative Technology for Schoolchildren.

ERIC Educational Resources Information Center

Stolyarov, Yuri

1981-01-01

Describes creative technology programs for elementary and secondary school children in the Soviet Union. Elementary school projects include aircraft, ship, and rocket models, amateur radio, electrical engineering, and electronics. Senior high school students design and build small-capacity vehicles, agricultural equipment, and electronic…

Outcome assessment for spasticity management in the patient with traumatic brain injury: the state of the art.

PubMed

Elovic, Elie P; Simone, Lisa K; Zafonte, Ross

2004-01-01

The objective of this article was to (1) review the engineering and medical literature to structure the available information concerning the assessment of spasticity in the neurological population; (2) to discuss the strengths and weaknesses of the different methods currently in use in spasticity assessment; and (3) make recommendations for future efforts in spasticity outcome assessment. Spasticity textbooks, Web sites, and OVID, IEEE, and Medline searches from 1966 through 2003 of spasticity, quantitative measure, or outcome assessment in the rehabilitation population were used as data sources. Over 500 articles were reviewed. Articles that discussed outcome measures used to assess interventions and evaluation of spasticity were included. Authors reviewed the articles looking at inclusion criteria, data collection, methodology, assessment methods, and conclusions for validity and relevance to this article. Issues such as clinical relevance, real-world function and lack of objectivity, and time consumed during performance are important issues for spasticity assessment. Some measures such as the Ashworth Scale remain in common use secondary to ease of use despite their obvious functional limitations. More functional outcome goals are plagued by being more time consuming and a general inability to demonstrate changes after an intervention. This may be secondary to the other factors that combine with spasticity to cause dysfunction at that level. Quantitative metrics can provide more objective measurements but their clinical relevance is sometimes problematic. The assessment of spasticity outcome is still somewhat problematic. Further work is necessary to develop measures that have real-world functional significance to both the individuals being treated and the clinicians. A lack of objectivity is still a problem. In the future it is important for clinicians and the engineers to work together in the development of better outcome measures.

Teachers' Level of Awareness of 21st Century Occupational Roles in Rivers State Secondary Schools

ERIC Educational Resources Information Center

Uche, Chineze M.; Kaegon, Leesi E. S. P.; Okata, Fanny Chiemezie

2016-01-01

This study investigated the teachers' level of awareness of 21st century occupational roles in Rivers state secondary schools. Three research questions and three hypotheses guided the study. The population of study comprised of 247 public secondary schools and 57 private secondary schools in Port Harcourt metropolis of Rivers state which gave a…

Accessing Nature’s diversity through metabolic engineering and synthetic biology

PubMed Central

King, Jason R.; Edgar, Steven; Qiao, Kangjian; Stephanopoulos, Gregory

2016-01-01

In this perspective, we highlight recent examples and trends in metabolic engineering and synthetic biology that demonstrate the synthetic potential of enzyme and pathway engineering for natural product discovery. In doing so, we introduce natural paradigms of secondary metabolism whereby simple carbon substrates are combined into complex molecules through “scaffold diversification”, and subsequent “derivatization” of these scaffolds is used to synthesize distinct complex natural products. We provide examples in which modern pathway engineering efforts including combinatorial biosynthesis and biological retrosynthesis can be coupled to directed enzyme evolution and rational enzyme engineering to allow access to the “privileged” chemical space of natural products in industry-proven microbes. Finally, we forecast the potential to produce natural product-like discovery platforms in biological systems that are amenable to single-step discovery, validation, and synthesis for streamlined discovery and production of biologically active agents. PMID:27081481

On the inlet vortex system. [preventing jet engine damage caused by debris pick-up

NASA Technical Reports Server (NTRS)

Bissinger, N. C.; Braun, G. W.

1974-01-01

The flow field of a jet engine with an inlet vortex, which can pick up heavy debris from the ground and damage the engine, was simulated in a small water tunnel by means of the hydrogen bubble technique. It was found that the known engine inlet vortex is accompained by a vortex system, consisting of two inlet vortices (the ground based and the trailing one), secondary vortices, and ground vortices. Simulation of the ground effect by an inlet image proved that the inlet vortex feeds on free stream vorticity and can exist without the presence of a ground boundary layer. The structural form of the inlet vortex system was explained by a simple potential flow model, which showed the number, location, and the importance of the stagnation points. A retractable horizontal screen or an up-tilt of the engine is suggested as countermeasure against debris ingestion.

A Thermodynamic Study of the Turbojet Engine

NASA Technical Reports Server (NTRS)

Pinkel, Benjamin; Karp, Irvin M

1947-01-01

Charts are presented for computing thrust, fuel consumption, and other performance values of a turbojet engine for any given set of operating conditions and component efficiencies. The effects of pressure losses in the inlet duct and the combustion chamber, of variation in physical properties of the gas as it passes through the system, of reheating of the gas due to turbine losses, and of change in mass flow by the addition of fuel are included. The principle performance chart shows the effects of primary variables and correction charts provide the effects of secondary variables and of turbine-loss reheat on the performance of the system. The influence of characteristics of a given compressor and turbine on performance of a turbojet engine containing a matched set of these given components is discussed for cases of an engine with a centrifugal-flow compressor and of an engine with an axial-flow compressor.

Education activities of the US Department of Energy's Office of Civilian Radioactive Waste Management

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, J.P.

1991-01-01

This paper reports that science education has long been a critical element in the U.S. Department of Energy's (DOE) Civilian Radioactive Waste Management Program. OCRWM has developed educational programs aimed at improving the science literacy of students from kindergarten through college and post-graduate levels, enhancing the skills of teachers, encouraging careers in science and engineering, and developing a keener awareness of science issues among the general population. Activities include interaction with educators in the development of curricula material; workshops for elementary and secondary students; cooperative agreements and projects with universities; OCRWM exhibit showings at technical and non-technical meetings and atmore » national and regional teacher/educator conferences; the OCRWM Fellowship Program; and support for Historically Black Colleges and Universities.« less

Engineering microbial hosts for production of bacterial natural products.

PubMed

Zhang, Mingzi M; Wang, Yajie; Ang, Ee Lui; Zhao, Huimin

2016-08-27

Covering up to end 2015Microbial fermentation provides an attractive alternative to chemical synthesis for the production of structurally complex natural products. In most cases, however, production titers are low and need to be improved for compound characterization and/or commercial production. Owing to advances in functional genomics and genetic engineering technologies, microbial hosts can be engineered to overproduce a desired natural product, greatly accelerating the traditionally time-consuming strain improvement process. This review covers recent developments and challenges in the engineering of native and heterologous microbial hosts for the production of bacterial natural products, focusing on the genetic tools and strategies for strain improvement. Special emphasis is placed on bioactive secondary metabolites from actinomycetes. The considerations for the choice of host systems will also be discussed in this review.

High Work, High-Efficiency Turbines for Uninhabited Aerial Vehicles (UAVs) Addendum to AFRL-RQ-WP-TR-2013-0198

DTIC Science & Technology

2013-09-01

followed by an exhaust nozzle . He considered the turbojet as a hybrid of “propeller gas turbine” and “rocket” principles. In 1936, he then conceived...first bench-test of a jet engine using liquid fuel. Simultaneous with Whittle, a German scientist was making great headway into gas turbine engine...deviations, secondary flows, and similar loss producing phenomena. The results are applicable to both military and civil applications of gas turbine

ETR HEAT EXCHANGER BUILDING, TRA644. WORKERS CHECK INTERIOR OF ONE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

ETR HEAT EXCHANGER BUILDING, TRA-644. WORKERS CHECK INTERIOR OF ONE OF THE TWELVE HEAT EXCHANGER UNITS. COOLANT FROM ETR WILL ENTER EXCHANGERS AT TEMPERATURE OF 137.5 DEGREES F. AND LEAVE THE SYSTEM AT 110 DEGREES F. SECONDARY WATER WILL ENTER AT 78 DEGREES F. AND LEAVE SYSTEM AT 110 DEGREES F. INL NEGATIVE NO. 56-3712. R.G. Larsen, Photographer, 11/13/1956 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

Automated Data Aggregation for Time-Series Analysis: Study Case on Anaesthesia Data Warehouse.

PubMed

Lamer, Antoine; Jeanne, Mathieu; Ficheur, Grégoire; Marcilly, Romaric

2016-01-01

Data stored in operational databases are not reusable directly. Aggregation modules are necessary to facilitate secondary use. They decrease volume of data while increasing the number of available information. In this paper, we present four automated engines of aggregation, integrated into an anaesthesia data warehouse. Four instances of clinical questions illustrate the use of those engines for various improvements of quality of care: duration of procedure, drug administration, assessment of hypotension and its related treatment.

Performance Charts for the Turbojet Engine

NASA Technical Reports Server (NTRS)

Pinkel, Benjamin; Karp, Irving M.

1947-01-01

Charts are presented for computing the thrust, fuel consumption, and other performance values of a turbojet engine for any given set of operating conditions and component efficiencies. The effects of the pressure losses in the inlet duct and combustion chamber, the variation in the physical properties of the gas as it passes through the cycle, and the change in mass flow by the addition of fuel are included. The principle performance charts show the effects of the primary variables and correction charts provide the effects of the secondary variables.

Structural engineering masters level education framework of knowledge for the needs of initial professional practice

NASA Astrophysics Data System (ADS)

Balogh, Zsuzsa Enriko

For at least the last decade, engineering, civil engineering, along with structural engineering as a profession within civil engineering, have and continue to face an emerging need for "Raising the Bar" of preparedness of young engineers seeking to become practicing professional engineers. The present consensus of the civil engineering profession is that the increasing need for broad and in-depth knowledge should require the young structural engineers to have at least a Masters-Level education. This study focuses on the Masters-Level preparedness in the structural engineering area within the civil engineering field. It follows much of the methodology used in the American Society of Civil Engineers (ASCE) Body of Knowledge determination for civil engineering and extends this type of study to better define the portion of the young engineers preparation beyond the undergraduate program for one specialty area of civil engineering. The objective of this research was to create a Framework of Knowledge for the young engineer which identifies and recognizes the needs of the profession, along with the profession's expectations of how those needs can be achieved in the graduate-level academic setting, in the practice environment, and through lifelong learning opportunities with an emphasis on the initial five years experience past completion of a Masters program in structural engineering. This study applied a modified Delphi method to obtain the critical information from members of the structural engineering profession. The results provide a Framework of Knowledge which will be useful to several groups seeking to better ensure the preparedness of the future young structural engineers at the Masters-Level.

Competency Profile Development for Management in Marketing Education on the Secondary Level and Cooperative Vocational/Industrial Education Programs on the Secondary Level.

ERIC Educational Resources Information Center

Smith, Clifton L.

A project revalidated, revised, and adapted/modified the minimum core competencies for the management and cooperative vocational/industrial education (CIE) courses on the secondary level. In Missouri, each marketing instructor teaching a management course and each CIE instructor completed a survey instrument for the assessment of each core…

Working at a Different Level? Curriculum Differentiation in Irish Lower Secondary Education

ERIC Educational Resources Information Center

Smyth, Emer

2018-01-01

Young people in Irish schools are required to choose whether to sit secondary exam subjects at higher or ordinary level. This paper draws on a mixed methods longitudinal study of students in 12 case-study schools to trace the factors influencing take-up of higher level subjects within lower secondary education. School organisation and process are…

Students' Conceptions of the Particulate Nature of Matter at Secondary and Tertiary Level

ERIC Educational Resources Information Center

Ayas, Alipasa; Ozmen, Haluk; Calik, Muammer

2010-01-01

The aim of the present study is to elicit students' understanding of the particulate nature of matter via a cross-age study ranging from secondary to tertiary educational levels. A questionnaire with five-item open-ended questions was administered to 166 students from the secondary to tertiary levels of education. In light of the findings, it can…

Women in Physics: A Caribbean Perspective

NASA Astrophysics Data System (ADS)

Tanner, Kandice

2009-03-01

This paper is concerned with aspects of post-secondary education of women in physics in the Caribbean, focusing more specifically on the main university campuses in Trinidad and Tobago, Jamaica, and Barbados. Within this framework, there are three institutions of tertiary education that provide for undergraduate and post-graduate studies in physics. On average, the bachelor-level graduating class is roughly 40% female. A great majority of these students go on to seek master's degrees in engineering. Among those enrolled in graduate programs featuring research in astronomy, materials science, environmental physics, medical physics, and quantum physics, 58% are female. Significant numbers of women from the selected countries and from the Caribbean region are engaged in bachelor and doctoral programs in physics abroad, but no formal survey is available to provide the relevant quantitative information. However, an attempt will be made to quantify this component. Based in part on personal experience, a comparison will be made between domestic and foreign educational pathways, in terms of access to resources, level of research training, and occupational opportunities following graduation.

The intersection of discipline and roles: Dr. Pauline Mack's story as an instrumental case study with implications for leadership in science, technology, engineering, and mathematics

NASA Astrophysics Data System (ADS)

Younkin, Winnifred Gail

Widespread concerns currently exist regarding our nation's ability to attract, educate, and retain talented, diverse individuals in STEM fields. These concerns are exacerbated by globalized competition and critical economic conditions. With these issues in mind, this instrumental case study was designed to examine the life story of Dr. Pauline Beery Mack in order to inform secondary and tertiary educational leadership in science, technology, engineering, and mathematics (STEM). Dr. Mack's life story was written from the interpretive view and analyzed through a number of theoretical frameworks appropriate to understanding the complexity of an individual in time and place: the psychobiosocial model, constructivism, creativity, perspective of the field, and the capstone framework of leadership. Data for the construction of Dr. Mack's life story were obtained from Pennsylvania State University Archives, The Women's Collection at Texas Woman's University (TWU), original publications, news media archives, and other sources. Interviews conducted for TWU's archives and interviews conducted by the author provided personal insight into Dr. Mack's life and work. Dr. Mack (1891-1974) lived, learned, created, and taught in a STEM arena that was predominately male. She pursued research with zeal, and was highly adept in attracting jobs, funding, students, and the right people to get the jobs done. Her longitudinal nutrition research, based on a methodology she invented, was innovative in its scope and scale. She served as an advocate for consumers, the undernourished, women, and minorities. Along the way, she changed perceptions of what women could accomplish. Bone density, school lunches, Victory Gardens, flammability, textile industry scandal, and space travel. Dr. Mack with her insatiable need to know was involved in it all. Her multiplicity of roles and contexts yielded a rich and complex life from which to draw implications for educational leadership in secondary and tertiary STEM fields. Implications for educational leadership in secondary and tertiary STEM fields that emerged from this study, relating to both affective and academic spheres, range from STEM valuing, discipline-related expertise, divergence value modeling, and expectations. Among the other implications addressed are levels of thinking, scaffolding for attribute development, and working on the work.

Integrated RNA-seq and sRNA-seq analysis reveals miRNA effects on secondary metabolism in Solanum tuberosum L.

PubMed

Qiao, Yan; Zhang, Jinjin; Zhang, Jinwen; Wang, Zhiwei; Ran, An; Guo, Haixia; Wang, Di; Zhang, Junlian

2017-02-01

Light is a major environmental factor that affects metabolic pathways and stimulates the production of secondary metabolites in potato. However, adaptive changes in potato metabolic pathways and physiological functions triggered by light are partly explained by gene expression changes. Regulation of secondary metabolic pathways in potato has been extensively studied at transcriptional level, but little is known about the mechanisms of post-transcriptional regulation by miRNAs. To identify light-responsive miRNAs/mRNAs and construct putative metabolism pathways regulated by the miRNA-mRNA pairs, an integrated omics (sRNAome and transcriptome) analysis was performed to potato under light stimulus. A total of 31 and 48 miRNAs were identified to be differentially expressed in the leaves and tubers, respectively. Among the DEGs, 1353 genes in the leaves and 1841 genes in the tubers were upregulated, while 1595 genes in the leaves and 897 genes in the tubers were downregulated by light. Mapman enrichment analyses showed that genes related to MVA pathway, alkaloids-like, phenylpropanoids, flavonoids, and carotenoids metabolism were significantly upregulated, while genes associated with major CHO metabolism were repressed in the leaves and tubers. Integrated miRNA and mRNA profiles revealed that light-responsive miRNAs are important regulators in alkaloids metabolism, UMP salvage, lipid biosynthesis, and cellulose catabolism. Moreover, several miRNAs may participate in glycoalkaloids metabolism via JA signaling pathway, UDP-glucose biosynthesis and hydroxylation reaction. This study provides a global view of miRNA and mRNA expression profiles in potato response to light, our results suggest that miRNAs might play important roles in secondary metabolic pathways, especially in glycoalkaloid biosynthesis. The findings will enlighten us on the genetic regulation of secondary metabolite pathways and pave the way for future application of genetically engineered potato.

Design and research of focusable secondary microprism in concentrating photovoltaic module

NASA Astrophysics Data System (ADS)

Guo, Limin; Liu, Youqiang; Zhao, Guoming; Wang, Zhiyong

2017-09-01

Low tracking accuracy of tracker, wind induced vibration of structure and lens deformation by temperature lead to non-vertical incident irradiation to the Fresnel lens, which necessitates a secondary concentrator in actual engineering application of concentrating photovoltaic module. This paper adds a secondary focusable microprism between Fresnel lens and solar cells in order to improve optical efficiency. The 3D model of microprism is established by SOLIDWORDS and main parameters are optimized using ZEMAX. Results show that combination of Fresnel lens and focusable microprism achieves a higher energy when the secondary microprism upper spherical diameter is 18mm, the opposite side face included angle is 116°, and the side length of the bottom is 2.15mm. The highest energy of solar cell surface can reach 2.4998W, improving 33.2%, and the module height with the secondary microprism is 88mm, which reduces by 5.5mm without secondary microprism. Experimental results show that the optical efficiency of 400X concentrating module system is 88.67%, the acceptance angle is ±1.2°, the 400X module maximum output power is 144.7W.

A Transcriptomic Analysis of Xylan Mutants Does Not Support the Existence of a Secondary Cell Wall Integrity System in Arabidopsis

PubMed Central

Faria-Blanc, Nuno; Mortimer, Jenny C.; Dupree, Paul

2018-01-01

Yeast have long been known to possess a cell wall integrity (CWI) system, and recently an analogous system has been described for the primary walls of plants (PCWI) that leads to changes in plant growth and cell wall composition. A similar system has been proposed to exist for secondary cell walls (SCWI). However, there is little data to support this. Here, we analyzed the stem transcriptome of a set of cell wall biosynthetic mutants in order to investigate whether cell wall damage, in this case caused by aberrant xylan synthesis, activates a signaling cascade or changes in cell wall synthesis gene expression. Our data revealed remarkably few changes to the transcriptome. We hypothesize that this is because cells undergoing secondary cell wall thickening have entered a committed programme leading to cell death, and therefore a SCWI system would have limited impact. The absence of transcriptomic responses to secondary cell wall alterations may facilitate engineering of the secondary cell wall of plants. PMID:29636762

A Transcriptomic Analysis of Xylan Mutants Does Not Support the Existence of a Secondary Cell Wall Integrity System in Arabidopsis.

PubMed

Faria-Blanc, Nuno; Mortimer, Jenny C; Dupree, Paul

2018-01-01

Yeast have long been known to possess a cell wall integrity (CWI) system, and recently an analogous system has been described for the primary walls of plants (PCWI) that leads to changes in plant growth and cell wall composition. A similar system has been proposed to exist for secondary cell walls (SCWI). However, there is little data to support this. Here, we analyzed the stem transcriptome of a set of cell wall biosynthetic mutants in order to investigate whether cell wall damage, in this case caused by aberrant xylan synthesis, activates a signaling cascade or changes in cell wall synthesis gene expression. Our data revealed remarkably few changes to the transcriptome. We hypothesize that this is because cells undergoing secondary cell wall thickening have entered a committed programme leading to cell death, and therefore a SCWI system would have limited impact. The absence of transcriptomic responses to secondary cell wall alterations may facilitate engineering of the secondary cell wall of plants.

Investigation of traffic count procedures on unpaved roads : final report.

DOT National Transportation Integrated Search

1995-04-01

This report inventoried the current costs and procedures of VDOT's : Secondary Count Program, with special attention to costs and procedures : for traffic counts on unpaved roads. A survey of VDOT's nine District : Traffic Engineers on unpaved road c...

Workstation Table Engineering Model Design, Development, Fabrication, and Testing

DOT National Transportation Integrated Search

2012-05-01

This research effort is focused on providing a workstation table design that will reduce the risk of occupant injuries due to secondary impacts and to compartmentalize the occupants to prevent impacts with other objects and/or passengers seated acros...

Workstation table engineering model design, development, fabrication, and testing

DOT National Transportation Integrated Search

2012-05-01

This research effort is focused on providing a workstation table design that will reduce the risk of occupant injuries due to secondary impacts and to compartmentalize the occupants to prevent impacts with other objects and/or passengers seated acros...

LEGO robot vehicle lesson plans for secondary education : a recruitment tool.

DOT National Transportation Integrated Search

2012-08-01

Robotics is a great way to get kids excited about science, technology, engineering, and math (STEM) topics. It is also highly effective in stimulation development of teamwork and self-confidence. This project provides transportation-related lesson pl...

Resources in Technology 4.

ERIC Educational Resources Information Center

Ritz, John M.; And Others

This document--intended to help technology education teachers plan their classroom curriculum for secondary school and college students--contains units on satellite communication, the nature and properties of engineering materials, careers in technology, new developments in printing, composite materials, ceramics, ceramic materials, and personal…

High freestream turbulence studies on a scaled-up stator vane

NASA Astrophysics Data System (ADS)

Radomsky, Roger William, Jr.

2000-10-01

Today's gas turbine engines are operating at combustor exit temperatures far exceeding the maximum temperatures of the component alloys downstream of the combustor. These higher temperatures are necessary to increase the efficiency of the engine, and, as such, durability of the downstream components becomes an issue. The highly turbulent flowfield that exists at the exit of the combustor complicates issues further by increasing heat transfer from the hot gas to the component surface. To account for the high heat transfer rates, and provide a better prediction of the applied heat loads, detailed heat transfer and flowfield information is needed at turbulence levels representative those exiting a combustor. Flowfield measurements at high freestream turbulence levels indicated that turbulence, which was isotropic at the inlet, became highly anisotropic in the test section as a result of surface curvature and strain. Turbulent kinetic energy levels were shown to increase in the passage by as much as 131% and 31% for the 10% and 19.5% turbulence levels. Although the turbulent kinetic energy was high, the turbulence level based upon local velocity decreased quickly to levels of 3% and 6% near the suction surface for the 10% and 19.5% turbulence levels. For the pressure surface, local turbulence levels were as high as 10% and 16% for the 10% and 19.5% turbulence levels. High local turbulence levels and heat transfer augmentation were observed near the stagnation location, by as much as 50%, and along the pressure surface, by as much as 80%, where airfoil geometries have shown degradation after prolonged usage. Endwall flowfield measurements on a plane at the stagnation location showed that a horseshoe vortex developed in the juncture region of the vane at high freestream. turbulence similar to that at low freestream turbulence. Measurements near the center of the vortex indicated that the vortex was highly unsteady. In regions where strong secondary flows (horseshoe and passage vortex) were present, these vortices dominated the heat transfer and the augmentations due to high freestream turbulence were small.

Expert vs. novice: Problem decomposition/recomposition in engineering design

NASA Astrophysics Data System (ADS)

Song, Ting

The purpose of this research was to investigate the differences of using problem decomposition and problem recomposition among dyads of engineering experts, dyads of engineering seniors, and dyads of engineering freshmen. Fifty participants took part in this study. Ten were engineering design experts, 20 were engineering seniors, and 20 were engineering freshmen. Participants worked in dyads to complete an engineering design challenge within an hour. The entire design process was video and audio recorded. After the design session, members participated in a group interview. This study used protocol analysis as the methodology. Video and audio data were transcribed, segmented, and coded. Two coding systems including the FBS ontology and "levels of the problem" were used in this study. A series of statistical techniques were used to analyze data. Interview data and participants' design sketches also worked as supplemental data to help answer the research questions. By analyzing the quantitative and qualitative data, it was found that students used less problem decomposition and problem recomposition than engineer experts in engineering design. This result implies that engineering education should place more importance on teaching problem decomposition and problem recomposition. Students were found to spend less cognitive effort when considering the problem as a whole and interactions between subsystems than engineer experts. In addition, students were also found to spend more cognitive effort when considering details of subsystems. These results showed that students tended to use dept-first decomposition and experts tended to use breadth-first decomposition in engineering design. The use of Function (F), Behavior (B), and Structure (S) among engineering experts, engineering seniors, and engineering freshmen was compared on three levels. Level 1 represents designers consider the problem as an integral whole, Level 2 represents designers consider interactions between subsystems, and Level 3 represents designers consider details of subsystems. The results showed that students used more S on Level 1 and 3 but they used less F on Level 1 than engineering experts. The results imply that engineering curriculum should improve the teaching of problem definition in engineering design because students need to understand the problem before solving it.

Collaborative Systems Thinking: A Response to the Problems Faced by Systems Engineering's 'Middle Tier'

NASA Technical Reports Server (NTRS)

Phfarr, Barbara B.; So, Maria M.; Lamb, Caroline Twomey; Rhodes, Donna H.

2009-01-01

Experienced systems engineers are adept at more than implementing systems engineering processes: they utilize systems thinking to solve complex engineering problems. Within the space industry demographics and economic pressures are reducing the number of experienced systems engineers that will be available in the future. Collaborative systems thinking within systems engineering teams is proposed as a way to integrate systems engineers of various experience levels to handle complex systems engineering challenges. This paper uses the GOES-R Program Systems Engineering team to illustrate the enablers and barriers to team level systems thinking and to identify ways in which performance could be improved. Ways NASA could expand its engineering training to promote team-level systems thinking are proposed.

Analyzing the Levels of Depressive Symptoms among Secondary School Students in Canada and Turkey

ERIC Educational Resources Information Center

Karatas, Zeynep; Tremblay, Richard Ernest

2015-01-01

To examine the level of depressive symptoms of the secondary school students in Turkey and Canada has been aimed in this study. The research group of the study consists of 1050 secondary school students with the average age of 13. Their socio-economic levels are low in both countries, Canada and Turkey. Data has been analyzed by independent groups…

Alignment of Hands-on STEM Engagement Activities with Positive STEM Dispositions in Secondary School Students

NASA Astrophysics Data System (ADS)

Christensen, Rhonda; Knezek, Gerald; Tyler-Wood, Tandra

2015-12-01

This study examines positive dispositions reported by middle school and high school students participating in programs that feature STEM-related activities. Middle school students participating in school-to-home hands-on energy monitoring activities are compared to middle school and high school students in a different project taking part in activities such as an after-school robotics program. Both groups are compared and contrasted with a third group of high school students admitted at the eleventh grade to an academy of mathematics and science. All students were assessed using the same science, technology, engineering and mathematics (STEM) dispositions instrument. Findings indicate that the after-school group whose participants self-selected STEM engagement activities, and the self-selected academy of mathematics and science group, each had highly positive STEM dispositions comparable to those of STEM professionals, while a subset of the middle school whole-classroom energy monitoring group that reported high interest in STEM as a career, also possessed highly positive STEM dispositions comparable to the STEM Professionals group. The authors conclude that several different kinds of hands-on STEM engagement activities are likely to foster or maintain positive STEM dispositions at the middle school and high school levels, and that these highly positive levels of dispositions can be viewed as a target toward which projects seeking to interest mainstream secondary students in STEM majors in college and STEM careers, can hope to aspire. Gender findings regarding STEM dispositions are also reported for these groups.

Relative importance of professional practice and engineering management competencies

NASA Astrophysics Data System (ADS)

Pons, Dirk

2016-09-01

Problem: The professional practice of engineering always involves engineering management, but it is difficult to know what specifically to include in the undergraduate curriculum. Approach: The population of New Zealand practising engineers was surveyed to determine the importance they placed on specific professional practice and engineering management competencies. Findings: Results show that communication and project planning were the two most important topics, followed by others as identified. The context in which practitioners use communication skills was found to be primarily with project management, with secondary contexts identified. The necessity for engineers to develop the ability to use multiple soft skills in an integrative manner is strongly supported by the data. Originality: This paper is one of only a few large-scale surveys of practising engineers to have explored the soft skill attributes. It makes a didactic contribution of providing a ranked list of topics which can be used for designing the curriculum and prioritising teaching effort, which has not previously been achieved. It yields the new insight that combinations of topics are sometimes more important than individual topics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Ai-Qun; Pratomo Juwono, Nina Kurniasih; Synthetic Biology Research Program, National University of Singapore, Singapore

Fatty acid derivatives, such as hydroxy fatty acids, fatty alcohols, fatty acid methyl/ethyl esters, and fatty alka(e)nes, have a wide range of industrial applications including plastics, lubricants, and fuels. Currently, these chemicals are obtained mainly through chemical synthesis, which is complex and costly, and their availability from natural biological sources is extremely limited. Metabolic engineering of microorganisms has provided a platform for effective production of these valuable biochemicals. Notably, synthetic biology-based metabolic engineering strategies have been extensively applied to refactor microorganisms for improved biochemical production. Here, we reviewed: (i) the current status of metabolic engineering of microbes that produce fattymore » acid-derived valuable chemicals, and (ii) the recent progress of synthetic biology approaches that assist metabolic engineering, such as mRNA secondary structure engineering, sensor-regulator system, regulatable expression system, ultrasensitive input/output control system, and computer science-based design of complex gene circuits. Furthermore, key challenges and strategies were discussed. Finally, we concluded that synthetic biology provides useful metabolic engineering strategies for economically viable production of fatty acid-derived valuable chemicals in engineered microbes.« less

Biomedical learning experiences for middle school girls sponsored by the Kansas State University Student Chapter of the IEEE EMBS.

PubMed

Gruber, Lucinda; Griffith, Connor; Young, Ethan; Sullivan, Adriann; Schuler, Jeff; Arnold-Christian, Susan; Warren, Steve

2009-01-01

Learning experiences for middle school girls are an effective means to steer young women toward secondary engineering curricula that they might not have otherwise considered. Sponsorship of such experiences by a collegiate student group is worthwhile, as it gives the group common purpose and places college students in a position to mentor these young women. This paper addresses learning experiences in different areas of bio-medical engineering offered to middle school girls in November 2008 via a day-long workshop entitled "Engineering The Body." The Kansas State University (KSU) Student Chapter of the IEEE Engineering in Medicine and Biology Society (EMBS) worked with the KSU Women in Engineering and Science Program (WESP) to design and sponsor these experiences, which addressed the areas of joint mechanics, electrocardiograms, membrane transport, computer mouse design, and audio filters for cochlear implants. Fifty five middle-school girls participated in this event, affirming the notion that biomedical engineering appeals to young women and that early education and recruitment efforts have the potential to expand the biomedical engineering talent pool.

Production of Fatty Acid-Derived Valuable Chemicals in Synthetic Microbes

PubMed Central

Yu, Ai-Qun; Pratomo Juwono, Nina Kurniasih; Leong, Susanna Su Jan; Chang, Matthew Wook

2014-01-01

Fatty acid derivatives, such as hydroxy fatty acids, fatty alcohols, fatty acid methyl/ethyl esters, and fatty alka(e)nes, have a wide range of industrial applications including plastics, lubricants, and fuels. Currently, these chemicals are obtained mainly through chemical synthesis, which is complex and costly, and their availability from natural biological sources is extremely limited. Metabolic engineering of microorganisms has provided a platform for effective production of these valuable biochemicals. Notably, synthetic biology-based metabolic engineering strategies have been extensively applied to refactor microorganisms for improved biochemical production. Here, we reviewed: (i) the current status of metabolic engineering of microbes that produce fatty acid-derived valuable chemicals, and (ii) the recent progress of synthetic biology approaches that assist metabolic engineering, such as mRNA secondary structure engineering, sensor-regulator system, regulatable expression system, ultrasensitive input/output control system, and computer science-based design of complex gene circuits. Furthermore, key challenges and strategies were discussed. Finally, we concluded that synthetic biology provides useful metabolic engineering strategies for economically viable production of fatty acid-derived valuable chemicals in engineered microbes. PMID:25566540

Advances in engineered microorganisms for improving metabolic conversion via microgravity effects.

PubMed

Huangfu, Jie; Zhang, Genlin; Li, Jun; Li, Chun

2015-01-01

As an extreme and unique environment, microgravity has significant effects on microbial cellular processes, such as cell growth, gene expression, natural pathways and biotechnological products. Application of microgravity effects to identify the regulatory elements in reengineering microbial hosts will draw much more attention in further research. In this commentary, we discuss the microgravity effects in engineered microorganisms for improving metabolic conversion, including cell growth kinetics, antimicrobial susceptibility, resistance to stresses, secondary metabolites production, recombinant protein production and enzyme activity, as well as gene expression changes. Application of microgravity effects in engineered microorganisms could provide valuable platform for innovative approaches in bioprocessing technology to largely improve the metabolic conversion efficacy of biopharmaceutical products.

Substitution of ceramics for high temperature alloys. [advantages of using silicon carbides and silicon nitrides in gas turbine engines

NASA Technical Reports Server (NTRS)

Probst, H. B.

1978-01-01

The high temperature capability of ceramics such as silicon nitride and silicon carbide can result in turbine engines of improved efficiency. Other advantages when compared to the nickel and cobalt alloys in current use are raw material availability, lower weight, erosion/corrosion resistance, and potentially lower cost. The use of ceramics in three different sizes of gas turbine is considered; these are the large utility turbines, advanced aircraft turbines, and small automotive turbines. Special consideration, unique to each of these applications, arise when one considers substituting ceramics for high temperature alloys. The effects of material substitutions are reviewed in terms of engine performance, operating economy, and secondary effects.

Yield improvement strategies for the production of secondary metabolites in plant tissue culture: silymarin from Silybum marianum tissue culture.

PubMed

AbouZid, S

2014-01-01

Plant cell culture can be a potential source for the production of important secondary metabolites. This technology bears many advantages over conventional agricultural methods. The main problem to arrive at a cost-effective process is the low productivity. This is mainly due to lack of differentiation in the cultured cells. Many approaches have been used to maximise the yield of secondary metabolites produced by cultured plant cells. Among these approaches: choosing a plant with a high biosynthetic capacity, obtaining efficient cell line for growth and production of metabolite of interest, manipulating culture conditions, elicitation, metabolic engineering and organ culture. This article gives an overview of the various approaches used to maximise the production of pharmaceutically important secondary metabolites in plant cell cultures. Examples of using these different approaches are shown for the production of silymarin from Silybum marianum tissue culture.

Where are the women? Campus climate and the degree aspirations of women in science, technology, engineering and mathematics programs

NASA Astrophysics Data System (ADS)

Schulz, Phyllis

Women remain underrepresented in science, technology, engineering, and mathematics (STEM) at all levels of higher education, which has become a concern in the competitive global marketplace. Using both quantitative and qualitative analysis, this dissertation sought to learn more about how the campus climate and self-concept influence the degree aspirations of female undergraduate students majoring in STEM programs. Using the Beginning Post-Secondary dataset, regression analyses showed that a student's initial degree aspirations, SAT scores, and interactions with faculty were all positively related to their degree aspirations three years later. Interviews with seven current STEM undergraduates confirmed the importance of interaction with faculty and suggested undergraduate research and classroom experiences also play a role in the degree aspirations of STEM students. Three of the seven students interviewed began their undergraduate educations as non-STEM majors, suggesting that the traditional STEM pipeline may no longer be the norm. These findings suggest that both future research and current practitioners should focus on undergraduate STEM classroom and research experiences. Additionally, the characteristics of students who switch into STEM majors should be explored so that we may continue to expand the number of students pursuing STEM degrees.

Accelerator-based conversion (ABC) of weapons plutonium: Plant layout study and related design issues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cowell, B.S.; Fontana, M.H.; Krakowski, R.A.

1995-04-01

In preparation for and in support of a detailed R and D Plan for the Accelerator-Based Conversion (ABC) of weapons plutonium, an ABC Plant Layout Study was conducted at the level of a pre-conceptual engineering design. The plant layout is based on an adaptation of the Molten-Salt Breeder Reactor (MSBR) detailed conceptual design that was completed in the early 1070s. Although the ABC Plant Layout Study included the Accelerator Equipment as an essential element, the engineering assessment focused primarily on the Target; Primary System (blanket and all systems containing plutonium-bearing fuel salt); the Heat-Removal System (secondary-coolant-salt and supercritical-steam systems); Chemicalmore » Processing; Operation and Maintenance; Containment and Safety; and Instrumentation and Control systems. Although constrained primarily to a reflection of an accelerator-driven (subcritical) variant of MSBR system, unique features and added flexibilities of the ABC suggest improved or alternative approaches to each of the above-listed subsystems; these, along with the key technical issues in need of resolution through a detailed R&D plan for ABC are described on the bases of the ``strawman`` or ``point-of-departure`` plant layout that resulted from this study.« less

Production of recombinant protein G through high-density fermentation of engineered bacteria as well as purification.

PubMed

Zhang, Hu-Cheng; Yang, Jun; Yang, Guo-Wei; Wang, Xiao-Jie; Fan, Hai-Tao

2015-08-01

Recombinant Streptococcus Protein G (PG) is a cell wall protein, which, when combined with mammal immunoglobulin, is used in separating antibody technology. High-density fermentation technologies using an engineered recombinant PG-producing bacteria as well as PG separation and purification technologies have a direct impact on the availability and application of PG. Through primary and secondary seed cultivation, a recombinant E. coli strain was subjected to high-density fermentation with controlled feed supplement concentration under stimulation with isopropyl β-D-1-thiogalactopyranoside. The present study investigated the effect of factors including inoculum size, oxygen levels, pH and the cultivating method on the fermentation process, as well as the effect of the separation and purification technologies, including ultrasonication, nickel column affinity chromatography, Sephadex G-25 gel filtration chromatography and diethylaminoethanol-sepharose fast flow ion exchange chromatography on the yield and purity of PG. The efficiency of extraction was detected using SDS-PAGE. High-density fermentation yielded 80-150 g/l of bacteria and 1 g PG was obtained from one liter broth. The present study delivered a highly efficient novel method via which PG can be obtained at a high concentration and a purity >95%.

Palingol: a declarative programming language to describe nucleic acids' secondary structures and to scan sequence database.

PubMed Central

Billoud, B; Kontic, M; Viari, A

1996-01-01

At the DNA/RNA level, biological signals are defined by a combination of spatial structures and sequence motifs. Until now, few attempts had been made in writing general purpose search programs that take into account both sequence and structure criteria. Indeed, the most successful structure scanning programs are usually dedicated to particular structures and are written using general purpose programming languages through a complex and time consuming process where the biological problem of defining the structure and the computer engineering problem of looking for it are intimately intertwined. In this paper, we describe a general representation of structures, suitable for database scanning, together with a programming language, Palingol, designed to manipulate it. Palingol has specific data types, corresponding to structural elements-basically helices-that can be arranged in any way to form a complex structure. As a consequence of the declarative approach used in Palingol, the user should only focus on 'what to search for' while the language engine takes care of 'how to look for it'. Therefore, it becomes simpler to write a scanning program and the structural constraints that define the required structure are more clearly identified. PMID:8628670

Multilayer Impregnated Fibrous Thermal Insulation Tiles

NASA Technical Reports Server (NTRS)

Tran, Huy K.; Rasky, Daniel J.; Szalai, Christine e.; Hsu, Ming-ta; Carroll, Joseph A.

2007-01-01

The term "secondary polymer layered impregnated tile" ("SPLIT") denotes a type of ablative composite-material thermal- insulation tiles having engineered, spatially non-uniform compositions. The term "secondary" refers to the fact that each tile contains at least two polymer layers wherein endothermic reactions absorb considerable amounts of heat, thereby helping to prevent overheating of an underlying structure. These tiles were invented to afford lighter-weight alternatives to the reusable thermal-insulation materials heretofore variously used or considered for use in protecting the space shuttles and other spacecraft from intense atmospheric-entry heating.