Science.gov

Sample records for mechanical engineering sector

  1. The main problems in the mechanical engineering sector and some possible directions of their solution

    NASA Astrophysics Data System (ADS)

    Strizhakova, E.

    2016-04-01

    The article shows the problems of the sector of mechanical engineering in the industrial system in Russia. The author's method of estimating the relative level of risk and the method of determining the de-industrialization degree of the sector based on the aggregated level of adaptability are given. According to them we have analysed the key indicators, such as basic, developed and advanced technologies, and investments in an old or new technology of industrial sectors. The main directions of the impact of industrial policy allowing a change in the current situation in mechanical engineering are given. The results can be applied in practice in formation of directions and actual control actions to improve the overall efficiency of mechanical engineering industry.

  2. Mechanical Engineering Technology Curriculum.

    ERIC Educational Resources Information Center

    Georgia State Univ., Atlanta. Dept. of Vocational and Career Development.

    This guide offers information and procedures necessary to train mechanical engineering technicians. Discussed first are the rationale and objectives of the curriculum. The occupational field of mechanical engineering technology is described. Next, a curriculum model is set forth that contains information on the standard mechanical engineering…

  3. HSCT Sector Combustor Evaluations for Demonstration Engine

    NASA Technical Reports Server (NTRS)

    Greenfield, Stuart; Heberling, Paul; Kastl, John; Matulaitis, John; Huff, Cynthia

    2004-01-01

    In LET Task 10, critical development issues of the HSCT lean-burn low emissions combustor were addressed with a range of engineering tools. Laser diagnostics and CFD analysis were applied to develop a clearer understanding of the fuel-air premixing process and premixed combustion. Subcomponent tests evaluated the emissions and operability performance of the fuel-air premixers. Sector combustor tests evaluated the performance of the integrated combustor system. A 3-cup sector was designed and procured for laser diagnostics studies at NASA Glenn. The results of these efforts supported the earlier selection of the Cyclone Swirler as the pilot stage premixer and the IMFH (Integrated Mixer Flame Holder) tube as the main stage premixer of the LPP combustor. In the combustor system preliminary design subtask, initial efforts to transform the sector combustor design into a practical subscale engine combustor met with significant challenges. Concerns about the durability of a stepped combustor dome and the need for a removable fuel injection system resulted in the invention and refinement of the MRA (Multistage Radial Axial) combustor system in 1994. The MRA combustor was selected for the HSR Phase II LPP subscale combustor testing in the CPC Program.

  4. Ann Wagner, Mechanical Engineer.

    ERIC Educational Resources Information Center

    Bennett, Betsy K.

    1996-01-01

    Presents a profile of Ann Wagner, a mechanical engineer at the Goddard Space Flight Center in Maryland, and her job responsibilities there. Also includes a brief history of mechanical engineering as well as a sample graph and data activity sheet with answers. (AIM)

  5. Institute for Mechanical Engineering

    NASA Astrophysics Data System (ADS)

    The Institute of Mechanical Engineering has the objectives of supporting in Canada the following activities: improvement of vehicles, propulsion systems, and transportation-related facilities and services; improvements in the design and operation of maritime engineering works; protection of the environment; enhancement of energy flexibility; advancement of firms engaged in manufacturing and resource extraction; and related programs of other government departments and agencies. In 1990-91 the Institute, which had changed its name that year from the Division of Mechanical Engineering, consolidated its research activities from nine laboratories to six programs. Activities in these six programs are described: Advanced Manufacturing Technology, Coastal Zone Engineering, Cold Regions Engineering, Combustion and Fluids Engineering, Ground Transportation Technology, and Machinery and Engine Technology.

  6. Basic Engineer Equipment Mechanic.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the skills needed by basic engineer equipment mechanics. Addressed in the four individual units of the course are the following topics: mechanics and their tools (mechanics, hand tools, and power…

  7. Engineer Equipment Mechanic.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    Developed as part of the Marine Corps Institute (MCI) correspondence training program, this course on engineer equipment mechanics is designed to advance the professional competence of privates through sergeants as equipment mechanics, Military Occupation Specialty 1341, and is adaptable for nonmilitary instruction. Introductory materials include…

  8. Engine & Vehicle Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

    This competency-based curriculum includes all competencies a student will acquire in an engine and vehicle mechanics educational program. It follows guidelines established for automobile technician training programs leading toward certification and addresses requirements of the National Institute for Automotive Service Excellence (ASE). The…

  9. Mechanical engineering in hospitals.

    PubMed

    Wallington, J W

    1980-10-01

    The design of a modern hospital owes more to engineering than the layman may realize. In this context, many engineers are in the position of laymen, being unfamiliar with the multitude of services that lies behind the impressive facade of a modern hospital. In recent years medicine and surgery themselves have taken on many of the characteristics of a technology. This has required a matching development of the services both mechanical and electrical that are required in modern health care buildings. In medical terms, if the architectural features provide the 'skin' of the hospital, the mechanical and electrical engineering services provide the nerves and sinews. If we take as an example the recently completed Freeman Hospital, Newcastle upon Tyne, (Fig. 1), which cost 10 million pounds at current cost, the service network was responsible for about half the total cost. About 400 miles (643 km) of electrical wiring and more than 40 mile (64.5 km) of copper and steel piping were used to service 3000 separate rooms. This compares with percentages of between 18 and 25 per cent for other large buildings such as office blocks, hotels and sports complexes. PMID:10273268

  10. Activities of the Institute for Mechanical Engineering

    NASA Astrophysics Data System (ADS)

    The Institute of Mechanical Engineering (IME) is part of Canada's National Research Council. Its mission is to undertake, support, promote, and disseminate research and development in the mechanical engineering aspects of three vital sectors of the Canadian economy: transportation, resource industries, and manufacturing. The IME achieves its mission by performing research and development in its own facilities; by developing, providing, and transferring expertise and knowledge; by making its research facilities available to collaborators and clients; and by participating in international liaison and collaborative research activities. Six research programs are conducted in the IME: Advanced Manufacturing Technology; Coastal Zone Engineering; Cold Regions Engineering; Combustion and Fluids Engineering; Ground Transportation Technology; and Machinery and Engine Technology. The rationale and major research thrusts of each program are described, and specific achievements in 1991-92 are reviewed. Lists of technical reports and papers presented by IME personnel are also included.

  11. Competences in demand within the Spanish agricultural engineering sector

    NASA Astrophysics Data System (ADS)

    Perdigones, Alicia; Valera, Diego Luis; Moreda, Guillermo Pedro; García, Jose Luis

    2014-09-01

    The Rural Engineering Department (Technical University of Madrid) ran three competence surveys during the 2006-2007 and 2007-2008 academic years and evaluated: (1) the competences gained by agricultural engineer's degree and agricultural technical engineer's degree students (360 respondents); (2) the competences demanded by agricultural employers (50 farming sector employers); (3) competences required by farming sector professionals and former students (70 professionals). The surveys show significant differences between what competences agricultural employers require of graduates and the competences they acquire during their agricultural engineering degree courses. Recruiters are looking for generic competences such as the ability to coordinate groups and place less importance on knowledge of engineering, biology, applied economics and legislation. Of the computer-related competences, those most in demand by sector professionals were related to the use of Microsoft Office/Excel (used by 79% of professionals). Surveys were used to redesign some subjects of the degrees.

  12. Trigger mechanism for engines

    SciTech Connect

    Clark, L.R.

    1989-02-28

    A trigger mechanism is described for a blower-vacuum apparatus having a trigger mounted within a handle and a small engine comprising: a throttle; a ''L'' shaped lever having first and second legs mounted for rotation about an intermediate pivot within the handle when the trigger is depressed, interconnecting the trigger and the throttle, the second leg having first teeth defined therein, the lever further having idle, full throttle and stop positions; a normally raised latch means adapted to be rotated and axially depressed, the latch means having second teeth situated on a cam to engage the first teeth for holding the lever in an intermediate position between the idle and full throttle positions when the latch means is rotated. The latch means further are cam teeth into potential engagement with the lever teeth when the trigger is depressed, lever is biased to the stop position; and idle adjusting means means for intercepting the second leg for preventing the second leg from reaching the stop position when the latch means is raised.

  13. Diesel Engine Mechanics.

    ERIC Educational Resources Information Center

    Foutes, William A.

    Written in student performance terms, this curriculum guide on diesel engine repair is divided into the following eight sections: an orientation to the occupational field and instructional program; instruction in operating principles; instruction in engine components; instruction in auxiliary systems; instruction in fuel systems; instruction in…

  14. Job Prospects for Mechanical Engineers.

    ERIC Educational Resources Information Center

    Basta, Nicholas

    1986-01-01

    Discusses the career outlook for mechanical engineers. Explains that the number of bachelor degrees awarded yearly has reached a plateau, but salaries continue to rise. Suggests that the largest increase in demand for mechanical engineers will come from industries involved in automation, particularly those developing robotics. (TW)

  15. Job Prospects for Mechanical Engineers.

    ERIC Educational Resources Information Center

    Basta, Nicholas

    1985-01-01

    Indicates that the healthy economy is providing multiple opportunities for graduating mechanical engineers (including more job offers and higher pay) and that greatly expanded funding of military-defense work and computer applications are contributing to this growth. Data on mechanical engineering degrees granted, salaries, and industry growth are…

  16. Mechanical Engineering Department Technical Review

    SciTech Connect

    Carr, R.B.; Denney, R.M.

    1981-07-01

    The Mechanical Engineering Department Technical Review is published to inform readers of various technical activities within the Department, promote exchange of ideas, and give credit to personnel who are achieving the results. The report is presented in two parts: technical achievements and publication abstracts. The first is divided into seven sections, each of which reports on an engineering division and its specific activities related to nuclear tests, nuclear explosives, weapons, energy systems, engineering sciences, magnetic fusion, and materials fabrication.

  17. Mechanical Engineering Department technical abstracts

    SciTech Connect

    Not Available

    1984-07-01

    The Mechanical Engineering Department publishes abstracts twice a year to inform readers of the broad range of technical activities in the Department, and to promote an exchange of ideas. Details of the work covered by an abstract may be obtained by contacting the author(s). General information about the current role and activities of each of the Department's seven divisions precedes the technical abstracts. Further information about a division's work may be obtained from the division leader, whose name is given at the end of each divisional summary. The Department's seven divisions are as follows: Nuclear Test Engineering Division, Nuclear Explosives Engineering Division, Weapons Engineering Division, Energy Systems Engineering Division, Engineering Sciences Division, Magnetic Fusion Engineering Division and Materials Fabrication Division.

  18. The private sector's role in public sector genetically engineered crop projects.

    PubMed

    Potrykus, Ingo

    2010-11-30

    There is widespread interest within academia to work on public good genetically engineered (GE) projects to the benefit of the poor, especially to use GE-technology to contribute to food security. Not a single product from this work has reached the market. The major cause is GE-regulation, which prevents use of the technology for public good beyond proof-of-concept (Potrykus, I. (2010) Lessons from the Humanitarian Golden Rice project: Regulation prevents development of public good GE-products (these Proceedings)). There is, however, another key problem responsible for the lack of deployment of public good GE-plants: the public sector is incompetent and disinterested for work beyond proof-of-concept, and has neither capability nor funding to develop GE-plant products and introduce them to growers and consumers. The private sector has the expertise for both and in the right circumstances can be ready to support the public sector in public good enterprises. Public-private-partnerships are the best solution so far, to advance exploitation of GE-technology to the benefit of the poor. Public-private-partnerships are viable, however, only, if there is mutual interest from the private sector and initiative and funding from the public sector. PMID:20637908

  19. Composite mechanics for engine structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1989-01-01

    Recent research activities and accomplishments at Lewis Research Center on composite mechanics for engine structures are summarized. The activities focused mainly on developing procedures for the computational simulation of composite intrinsic and structural behavior. The computational simulation encompasses all aspects of composite mechanics, advanced three-dimensional finite-element methods, damage tolerance, composite structural and dynamic response, and structural tailoring and optimization.

  20. Composite mechanics for engine structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1987-01-01

    Recent research activities and accomplishments at Lewis Research Center on composite mechanics for engine structures are summarized. The activities focused mainly on developing procedures for the computational simulation of composite intrinsic and structural behavior. The computational simulation encompasses all aspects of composite mechanics, advanced three-dimensional finite-element methods, damage tolerance, composite structural and dynamic response, and structural tailoring and optimization.

  1. Energy efficient engine sector combustor rig test program

    NASA Technical Reports Server (NTRS)

    Dubiel, D. J.; Greene, W.; Sundt, C. V.; Tanrikut, S.; Zeisser, M. H.

    1981-01-01

    Under the NASA-sponsored Energy Efficient Engine program, Pratt & Whitney Aircraft has successfully completed a comprehensive combustor rig test using a 90-degree sector of an advanced two-stage combustor with a segmented liner. Initial testing utilized a combustor with a conventional louvered liner and demonstrated that the Energy Efficient Engine two-stage combustor configuration is a viable system for controlling exhaust emissions, with the capability to meet all aerothermal performance goals. Goals for both carbon monoxide and unburned hydrocarbons were surpassed and the goal for oxides of nitrogen was closely approached. In another series of tests, an advanced segmented liner configuration with a unique counter-parallel FINWALL cooling system was evaluated at engine sea level takeoff pressure and temperature levels. These tests verified the structural integrity of this liner design. Overall, the results from the program have provided a high level of confidence to proceed with the scheduled Combustor Component Rig Test Program.

  2. Bellcrank mechanisms for Stirling engines

    SciTech Connect

    Senft, J.R.; Senft, V.J.

    1996-12-31

    This paper describes a family of linkage drive systems for Stirling engines containing several new members. These mechanisms are adaptable to all three configurations of Stirling engine, impose minimal side loads on pistons and displacer rods, and include compact forms suitable for pressurized high performance engines. This group of drive systems is generated by a simple common scheme. Near sinusoidal motion is taken from a crankshaft carrying a single crankpin by two connecting rods each driving a bellcrank. The stationary pivots of the bellcranks are located so that their oscillatory motion has the phase angle separation required between the piston and displacer. The bellcranks are further configured to bring the third pin motion to a location suitable for coupling with the piston or displacer of the engine in a way which minimizes side loading. The paper presents a number of new linkage drives from the dual bellcrank family and indicates how they are embodied in beta and alpha type Stirling engines. The paper includes a design for a small multipurpose engine incorporating one of the subject mechanisms.

  3. Damage mechanics in engineering materials

    SciTech Connect

    Voyiadjis, G.Z.; Woody Ju, J.W.; Chaboche, J.L.

    1998-12-31

    This book contains thirty peer-reviewed papers that are based on the presentations made at the symposium on Damage Mechanics in Engineering Materials on the occasion of the Joint ASME/ASCE/SES Mechanics Conference (McNU97), held in Evanston, Illinois, June 28--July 2, 1997. The key area of discussion was on the constitutive modeling of damage mechanics in engineering materials encompassing the following topics: macromechanics/micromechanical constitutive modeling, experimental procedures, numerical modeling, inelastic behavior, interfaces, damage, fracture, failure, computational methods. The book is divided into six parts: study of damage mechanics; localization and damage; damage in brittle materials; damage in metals and metal matrix composites; computational aspects of damage models; damage in polymers and elastomers.

  4. Mechanical Autonomous Stochastic Heat Engine.

    PubMed

    Serra-Garcia, Marc; Foehr, André; Molerón, Miguel; Lydon, Joseph; Chong, Christopher; Daraio, Chiara

    2016-07-01

    Stochastic heat engines are devices that generate work from random thermal motion using a small number of highly fluctuating degrees of freedom. Proposals for such devices have existed for more than a century and include the Maxwell demon and the Feynman ratchet. Only recently have they been demonstrated experimentally, using, e.g., thermal cycles implemented in optical traps. However, recent experimental demonstrations of classical stochastic heat engines are nonautonomous, since they require an external control system that prescribes a heating and cooling cycle and consume more energy than they produce. We present a heat engine consisting of three coupled mechanical resonators (two ribbons and a cantilever) subject to a stochastic drive. The engine uses geometric nonlinearities in the resonating ribbons to autonomously convert a random excitation into a low-entropy, nonpassive oscillation of the cantilever. The engine presents the anomalous heat transport property of negative thermal conductivity, consisting in the ability to passively transfer energy from a cold reservoir to a hot reservoir. PMID:27419553

  5. Mechanical Autonomous Stochastic Heat Engine

    NASA Astrophysics Data System (ADS)

    Serra-Garcia, Marc; Foehr, André; Molerón, Miguel; Lydon, Joseph; Chong, Christopher; Daraio, Chiara

    2016-07-01

    Stochastic heat engines are devices that generate work from random thermal motion using a small number of highly fluctuating degrees of freedom. Proposals for such devices have existed for more than a century and include the Maxwell demon and the Feynman ratchet. Only recently have they been demonstrated experimentally, using, e.g., thermal cycles implemented in optical traps. However, recent experimental demonstrations of classical stochastic heat engines are nonautonomous, since they require an external control system that prescribes a heating and cooling cycle and consume more energy than they produce. We present a heat engine consisting of three coupled mechanical resonators (two ribbons and a cantilever) subject to a stochastic drive. The engine uses geometric nonlinearities in the resonating ribbons to autonomously convert a random excitation into a low-entropy, nonpassive oscillation of the cantilever. The engine presents the anomalous heat transport property of negative thermal conductivity, consisting in the ability to passively transfer energy from a cold reservoir to a hot reservoir.

  6. Mechanical Engineering Department. Technical review

    SciTech Connect

    Simecka, W.B.; Condouris, R.A.; Talaber, C.

    1980-01-01

    The Mechanical Engineering Department Technical Review is published to (1) inform the readers of various technical activities within the Department, (2) promote exchange of ideas, and (3) give credit to the personnel who are achieving the results. The report is formatted into two parts: technical achievements and publication abstracts. The first is divided into eight sections, one for each Division in the Department providing the reader with the names of the personnel and the Division accomplishing the work.

  7. Mechanical Engineering Department technical abstracts

    SciTech Connect

    Denney, R.M.

    1982-07-01

    The Mechanical Engineering Department publishes listings of technical abstracts twice a year to inform readers of the broad range of technical activities in the Department, and to promote an exchange of ideas. Details of the work covered by an abstract may be obtained by contacting the author(s). Overall information about current activities of each of the Department's seven divisions precedes the technical abstracts.

  8. Mechanical engineering department technical review

    SciTech Connect

    Carr, R.B. Denney, R.M.

    1981-01-01

    The Mechanical Engineering Department Technical Review is published to: (1) inform the readers of various technical activities within the department, (2) promote exchange of ideas, and (3) give credit to the personnel who are achieving the results. The report is formatted into two parts: technical acievements and publication abstracts. The first is divided into eight sections, one for each division in the department providing the reader with the names of the personnel and the division accomplishing the work.

  9. 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…

  10. Expose Mechanical Engineering Students to Biomechanics Topics

    ERIC Educational Resources Information Center

    Shen, Hui

    2011-01-01

    To adapt the focus of engineering education to emerging new industries and technologies nationwide and in the local area, a biomechanics module has been developed and incorporated into a mechanical engineering technical elective course to expose mechanical engineering students at ONU (Ohio Northern University) to the biomedical engineering topics.…

  11. SMAP Instrument Mechanical System Engineering

    NASA Technical Reports Server (NTRS)

    Slimko, Eric; French, Richard; Riggs, Benjamin

    2013-01-01

    The Soil Moisture Active Passive (SMAP) mission, scheduled for launch by the end of 2014, is being developed to measure the soil moisture and soil freeze/thaw state on a global scale over a three-year period. The accuracy, resolution, and global coverage of SMAP measurements are invaluable across many science and applications disciplines including hydrology, climate, carbon cycle, and the meteorological, environment, and ecology applications communities. The SMAP observatory is composed of a despun bus and a spinning instrument platform that includes both a deployable 6 meter aperture low structural frequency Astromesh reflector and a spin control system. The instrument section has engendered challenging mechanical system issues associated with the antenna deployment, flexible antenna pointing in the context of a multitude of disturbances, spun section mass properties, spin control system development, and overall integration with the flight system on both mechanical and control system levels. Moreover, the multitude of organizations involved, including two major vendors providing the spin subsystem and reflector boom assembly plus the flight system mechanical and guidance, navigation, and control teams, has led to several unique system engineering challenges. Capturing the key physics associated with the function of the flight system has been challenging due to the many different domains that are applicable. Key interfaces and operational concepts have led to complex negotiations because of the large number of organizations that integrate with the instrument mechanical system. Additionally, the verification and validation concerns associated with the mechanical system have had required far-reaching involvement from both the flight system and other subsystems. The SMAP instrument mechanical systems engineering issues and their solutions are described in this paper.

  12. Mechanical Engineering Department technical review

    SciTech Connect

    Carr, R.B.; Abrahamson, L.; Denney, R.M.; Dubois, B.E

    1982-01-01

    Technical achievements and publication abstracts related to research in the following Divisions of Lawrence Livermore Laboratory are reported in this biannual review: Nuclear Fuel Engineering; Nuclear Explosives Engineering; Weapons Engineering; Energy Systems Engineering; Engineering Sciences; Magnetic Fusion Engineering; and Material Fabrication. (LCL)

  13. Technical abstracts: Mechanical engineering, 1990

    SciTech Connect

    Broesius, J.Y.

    1991-03-01

    This document is a compilation of the published, unclassified abstracts produced by mechanical engineers at Lawrence Livermore National Laboratory (LLNL) during the calendar year 1990. Many abstracts summarize work completed and published in report form. These are UCRL-JC series documents, which include the full text of articles to be published in journals and of papers to be presented at meetings, and UCID reports, which are informal documents. Not all UCIDs contain abstracts: short summaries were generated when abstracts were not included. Technical Abstracts also provides descriptions of those documents assigned to the UCRL-MI (miscellaneous) category. These are generally viewgraphs or photographs presented at meetings. An author index is provided at the back of this volume for cross referencing.

  14. Wentworth Institute Mechanical Engineering Laboratory Manual.

    ERIC Educational Resources Information Center

    Avakian, Harry; And Others

    This publication is a Mechanical Engineering Laboratory Manual designed to be used by technical institute students in Mechanical Engineering Technology Programs. The experiments are introductory in nature and embrace the fields of applied thermodynamics, fluid mechanics, refrigeration, heat transfer and basic instrumentation. There are 20…

  15. Small Engines and Outboard Marine Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

    This competency-based curriculum guide is a handbook for the development of small engine and outboard marine mechanics programs. Based on a survey of Alaskan small engines and marine mechanics employers, it includes all competencies a student should acquire in such a mechanics program. The handbook stresses the importance of understanding the…

  16. Teaching Continuum Mechanics in a Mechanical Engineering Program

    ERIC Educational Resources Information Center

    Liu, Yucheng

    2011-01-01

    This paper introduces a graduate course, continuum mechanics, which is designed for and taught to graduate students in a Mechanical Engineering (ME) program. The significance of continuum mechanics in engineering education is demonstrated and the course structure is described. Methods used in teaching this course such as topics, class…

  17. Defining the Australian Mechanical Engineer

    ERIC Educational Resources Information Center

    Ferguson, Clive

    2006-01-01

    The attribute focus in engineering education now adopted by the engineering education accrediting bodies of the US, UK and Australia is based on meeting the assumed needs of professional practice. It is associated with an increasing expectation by employers of work-ready graduates rather than relying on subsequent work-based learning and…

  18. Competences in Demand within the Spanish Agricultural Engineering Sector

    ERIC Educational Resources Information Center

    Perdigones, Alicia; Valera, Diego Luis; Moreda, Guillermo Pedro; García, Jose Luis

    2014-01-01

    The Rural Engineering Department (Technical University of Madrid) ran three competence surveys during the 2006-2007 and 2007-2008 academic years and evaluated: (1) the competences gained by agricultural engineer's degree and agricultural technical engineer's degree students (360 respondents); (2) the competences demanded by agricultural…

  19. Gasoline Engine Mechanics. Florida Vocational Program Guide.

    ERIC Educational Resources Information Center

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

    This vocational program guide is intended to assist in the organization, operation, and evaluation of a program in gasoline engine mechanics in school districts, area vocational centers, and community colleges. The following topics are covered: job duties of small-engine mechanics; program content (curriculum framework and student performance…

  20. Standardized Curriculum for Outboard Marine Engine Mechanics.

    ERIC Educational Resources Information Center

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

    This curriculum guide for outboard marine engine mechanics was developed by the state of Mississippi to standardize vocational education course titles and core contents. The objectives contained in this document are common to all outboard marine engine mechanics programs in the state. The guide contains objectives for outboard marine engine…

  1. Mechanical autonomous stochastic heat engines

    NASA Astrophysics Data System (ADS)

    Serra-Garcia, Marc; Foehr, Andre; Moleron, Miguel; Lydon, Joseph; Chong, Christopher; Daraio, Chiara; . Team

    Stochastic heat engines extract work from the Brownian motion of a set of particles out of equilibrium. So far, experimental demonstrations of stochastic heat engines have required extreme operating conditions or nonautonomous external control systems. In this talk, we will present a simple, purely classical, autonomous stochastic heat engine that uses the well-known tension induced nonlinearity in a string. Our engine operates between two heat baths out of equilibrium, and transfers energy from the hot bath to a work reservoir. This energy transfer occurs even if the work reservoir is at a higher temperature than the hot reservoir. The talk will cover a theoretical investigation and experimental results on a macroscopic setup subject to external noise excitations. This system presents an opportunity for the study of non equilibrium thermodynamics and is an interesting candidate for innovative energy conversion devices.

  2. Selection of software for mechanical engineering undergraduates

    NASA Astrophysics Data System (ADS)

    Cheah, C. T.; Yin, C. S.; Halim, T.; Naser, J.; Blicblau, A. S.

    2016-07-01

    A major problem with the undergraduate mechanical course is the limited exposure of students to software packages coupled with the long learning curve on the existing software packages. This work proposes the use of appropriate software packages for the entire mechanical engineering curriculum to ensure students get sufficient exposure real life design problems. A variety of software packages are highlighted as being suitable for undergraduate work in mechanical engineering, e.g. simultaneous non-linear equations; uncertainty analysis; 3-D modeling software with the FEA; analysis tools for the solution of problems in thermodynamics, fluid mechanics, mechanical system design, and solid mechanics.

  3. Mod I automotive Stirling engine mechanical development

    SciTech Connect

    Simetkosky, M.

    1984-01-01

    The Mod I Stirling engine was the first automotive Stirling engine designed specifically for automotive application. Testing of these engines has revealed several deficiencies in engine mechanical integrity which have been corrected by redesign or upgrade. The main deficiencies uncovered during the Mod I program lie in the combustion, auxiliary, main seal, and heater head areas. This paper will address each of the major area deficiencies in detail, and describe the corrective actions taken as they apply to the Mod I and the next Stirling-engine design, the Upgraded Mod I (a redesign to incorporate new materials for cost/weight reduction and improved performance).

  4. Profiles--Mechanical Engineering: Human Resources and Funding. Special Report. Surveys of Science Resources Series.

    ERIC Educational Resources Information Center

    Lane, Melissa J.

    This report was developed by the National Science Foundation to focus attention on a particular field of engineering. It addresses the human resources and funding for mechanical engineering programs through several perspectives. The first major section, "Personnel," discusses employment levels and trends, salaries, sectors of employment, jobs in…

  5. Mechanical equivalent of quantum heat engines.

    PubMed

    Arnaud, Jacques; Chusseau, Laurent; Philippe, Fabrice

    2008-06-01

    Quantum heat engines employ as working agents multilevel systems instead of classical gases. We show that under some conditions quantum heat engines are equivalent to a series of reservoirs at different altitudes containing balls of various weights. A cycle consists of picking up at random a ball from one reservoir and carrying it to the next, thereby performing or absorbing some work. In particular, quantum heat engines, employing two-level atoms as working agents, are modeled by reservoirs containing balls of weight 0 or 1. The mechanical model helps us prove that the maximum efficiency of quantum heat engines is the Carnot efficiency. Heat pumps and negative temperatures are considered. PMID:18643212

  6. Engineering mechanics: statics and dynamics. [Textbook

    SciTech Connect

    Sandor, B.I.

    1983-01-01

    The purpose of this textbook is to provide engineering students with basic learning material about statics and dynamics which are fundamental engineering subjects. The chapters contain information on: an introduction to engineering mechanics; forces on particles, rigid bodies, and structures; kinetics of particles, particle systems, and rigid bodies in motion; kinematics; mechanical vibrations; and friction, work, moments of inertia, and potential energy. Each chapter contains introductory material, the development of the essential equations, worked-out example problems, homework problems, and, finally, summaries of the essential methods and equations, graphically illustrated where appropriate. (LCL)

  7. Optimization of a relativistic quantum mechanical engine

    NASA Astrophysics Data System (ADS)

    Peña, Francisco J.; Ferré, Michel; Orellana, P. A.; Rojas, René G.; Vargas, P.

    2016-08-01

    We present an optimal analysis for a quantum mechanical engine working between two energy baths within the framework of relativistic quantum mechanics, adopting a first-order correction. This quantum mechanical engine, with the direct energy leakage between the energy baths, consists of two adiabatic and two isoenergetic processes and uses a three-level system of two noninteracting fermions as its working substance. Assuming that the potential wall moves at a finite speed, we derive the expression of power output and, in particular, reproduce the expression for the efficiency at maximum power.

  8. Computational structural mechanics for engine structures

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1989-01-01

    The computational structural mechanics (CSM) program at Lewis encompasses: (1) fundamental aspects for formulating and solving structural mechanics problems, and (2) development of integrated software systems to computationally simulate the performance/durability/life of engine structures. It is structured to mainly supplement, complement, and whenever possible replace, costly experimental efforts which are unavoidable during engineering research and development programs. Specific objectives include: investigate unique advantages of parallel and multiprocesses for: reformulating/solving structural mechanics and formulating/solving multidisciplinary mechanics and develop integrated structural system computational simulators for: predicting structural performances, evaluating newly developed methods, and for identifying and prioritizing improved/missing methods needed. Herein the CSM program is summarized with emphasis on the Engine Structures Computational Simulator (ESCS). Typical results obtained using ESCS are described to illustrate its versatility.

  9. Micro electromechanical systems (MEMS) for mechanical engineers

    SciTech Connect

    Lee, A. P., LLNL

    1996-11-18

    The ongoing advances in Microelectromechanical Systems (MEMS) are providing man-kind the freedom to travel to dimensional spaces never before conceivable. Advances include new fabrication processes, new materials, tailored modeling tools, new fabrication machines, systems integration, and more detailed studies of physics and surface chemistry as applied to the micro scale. In the ten years since its inauguration, MEMS technology is penetrating industries of automobile, healthcare, biotechnology, sports/entertainment, measurement systems, data storage, photonics/optics, computer, aerospace, precision instruments/robotics, and environment monitoring. It is projected that by the turn of the century, MEMS will impact every individual in the industrial world, totaling sales up to $14 billion (source: System Planning Corp.). MEMS programs in major universities have spawned up all over the United States, preparing the brain-power and expertise for the next wave of MEMS breakthroughs. It should be pointed out that although MEMS has been initiated by electrical engineering researchers through the involvement of IC fabrication techniques, today it has evolved such that it requires a totally multi-disciplinary team to develop useful devices. Mechanical engineers are especially crucial to the success of MEMS development, since 90% of the physical realm involved is mechanical. Mechanical engineers are needed for the design of MEMS, the analysis of the mechanical system, the design of testing apparatus, the implementation of analytical tools, and the packaging process. Every single aspect of mechanical engineering is being utilized in the MEMS field today, however, the impact could be more substantial if more mechanical engineers are involved in the systems level designing. In this paper, an attempt is made to create the pathways for a mechanical engineer to enter in the MEMS field. Examples of application in optics and medical devices will be used to illustrate how mechanical

  10. Mechanical Engineering Department engineering research: Annual report, FY 1986

    SciTech Connect

    Denney, R.M.; Essary, K.L.; Genin, M.S.; Highstone, H.H.; Hymer, J.D.; Taft, S.O.

    1986-12-01

    This report provides information on the five areas of research interest in LLNL's Mechanical Engineering Department. In Computer Code Development, a solid geometric modeling program is described. In Dynamic Systems and Control, structure control and structure dynamics are discussed. Fabrication technology involves machine cutting, interferometry, and automated optical component manufacturing. Materials engineering reports on composite material research and measurement of molten metal surface properties. In Nondestructive Evaluation, NMR, CAT, and ultrasound machines are applied to manufacturing processes. A model for underground collapse is developed. Finally, an alternative heat exchanger is investigated for use in a fusion power plant. Separate abstracts were prepared for each of the 13 reports in this publication. (JDH)

  11. 46 CFR 12.15-13 - Deck engine mechanic.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13 Shipping... ENDORSEMENTS Qualified Member of the Engine Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC or MMD endorsed as junior engineer....

  12. 46 CFR 12.15-13 - Deck engine mechanic.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13 Shipping... ENDORSEMENTS Qualified Member of the Engine Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC or MMD endorsed as junior engineer....

  13. 46 CFR 12.15-13 - Deck engine mechanic.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13 Shipping... ENDORSEMENTS Qualified Member of the Engine Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC or MMD endorsed as junior engineer....

  14. Mechanical engineering capstone senior design textbook

    NASA Astrophysics Data System (ADS)

    Barrett, Rolin Farrar, Jr.

    This textbook is intended to bridge the gap between mechanical engineering equations and mechanical engineering design. To that end, real-world examples are used throughout the book. Also, the material is presented in an order that follows the chronological sequence of coursework that must be performed by a student in the typical capstone senior design course in mechanical engineering. In the process of writing this book, the author surveyed the fifty largest engineering schools (as ranked by the American Society of Engineering Education, or ASEE) to determine what engineering instructors are looking for in a textbook. The survey results revealed a clear need for a textbook written expressly for the capstone senior design course as taught throughout the nation. This book is designed to meet that need. This text was written using an organizational method that the author calls the General Topics Format. The format gives the student reader rapid access to the information contained in the text. All manufacturing methods, and some other material presented in this text, have been presented using the General Topics Format. The text uses examples to explain the importance of understanding the environment in which the product will be used and to discuss product abuse. The safety content contained in this text is unique. The Safety chapter teaches engineering ethics and includes a step-by-step guide to resolving ethical conflicts. The chapter includes explanations of rules, recommendations, standards, consensus standards, key safety concepts, and the legal implications of product failure. Key design principles have been listed and explained. The text provides easy-to-follow design steps, helpful for both the student and new engineer. Prototyping is presented as consisting of three phases: organization, building, and refining. A chapter on common manufacturing methods is included for reference.

  15. Computational structural mechanics for engine structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1989-01-01

    The computational structural mechanics (CSM) program at Lewis encompasses the formulation and solution of structural mechanics problems and the development of integrated software systems to computationally simulate the performance, durability, and life of engine structures. It is structured to supplement, complement, and, whenever possible, replace costly experimental efforts. Specific objectives are to investigate unique advantages of parallel and multiprocessing for reformulating and solving structural mechanics and formulating and solving multidisciplinary mechanics and to develop integrated structural system computational simulators for predicting structural performance, evaluating newly developed methods, and identifying and prioritizing improved or missing methods.

  16. Computational structural mechanics for engine structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1988-01-01

    The computational structural mechanics (CSM) program at Lewis encompasses the formulation and solution of structural mechanics problems and the development of integrated software systems to computationally simulate the performance, durability, and life of engine structures. It is structured to supplement, complement, and, whenever possible, replace costly experimental efforts. Specific objectives are to investigate unique advantages of parallel and multiprocessing for reformulating and solving structural mechanics and formulating and solving multidisciplinary mechanics and to develop integrated structural system computational simulators for predicting structural performance, evaluating newly developed methods, and identifying and prioritizing improved or missing methods.

  17. The Educational Needs of Graduate Mechanical Engineers in New Zealand.

    ERIC Educational Resources Information Center

    Deans, J.

    1999-01-01

    Surveys graduate and undergraduate mechanical engineering students at the University of Auckland. Shows that the dominant work activities of New Zealand mechanical engineers include design and consultancy and that graduate engineers rapidly migrate into management. (Author/CCM)

  18. Thermodynamic Optimization of Flow Geometry in Mechanical and Civil Engineering

    NASA Astrophysics Data System (ADS)

    Bejan, Adrian; Lorente, Sylvie

    2001-12-01

    Recent developments in thermodynamic optimization are reviewed by focusing on the generation of optimal geometric form (shape, structure, topology) in flow systems. The flow configuration is free to vary. The principle that generates geometric form is the pursuit of maximum global performance (e.g., minimum flow resistance, minimum irreversibility) subject to global finiteness constraints (volume, weight, time). The resulting structures constructed in this manner have been named constructal designs. The thought that the same objective and constraints principle accounts for the optimally shaped flow paths that occur in natural systems (animate and inanimate) has been named constructal theory. Examples of large classes of applications are drawn from various sectors of mechanical and civil engineering: the distribution of heat transfer area in power plants, optimal sizing and shaping of flow channels and fins, optimal aspect ratios of heat exchanger core structures, aerodynamic and hydrodynamic shapes, tree-shaped assemblies of convective fins, treeshaped networks for fluid flow and other currents, optimal configurations for streams that undergo bifurcation or pairing, insulated pipe networks for the distribution of hot water and exergy over a fixed territory, and distribution networks for virtually everything that moves in society (goods, currency, information). The principle-based generation of flow geometry unites the thermodynamic optimization developments known in mechanical engineering with lesser known applications in civil engineering and social organization. This review extends thermodynamics, because it shows how thermodynamic principles of design optimization account for the development of optimal configurations in civil engineering and social organization.

  19. Auto Mechanics. Heavy Equipment. Small Engines.

    ERIC Educational Resources Information Center

    Finnerty, Kathy

    Developed for use in auto mechanics, Heavy Equipment Repair and Operation (HERO), and small engines programs, these study guides and supplemental worksheets cover operating principles, lubrication, cooling system, ignition circuit and electrical system, and fuel system. The worksheets and guide questions are phrased to emphasize key points…

  20. Gasoline Engine Mechanics. Performance Objectives. Intermediate Course.

    ERIC Educational Resources Information Center

    Jones, Marion

    Several intermediate performance objectives and corresponding criterion measures are listed for each of six terminal objectives presented in this curriculum guide for an intermediate gasoline engine mechanics course at the secondary level. (For the beginning course guide see CE 010 947.) The materials were developed for a two-semester (2 hour…

  1. 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)…

  2. Multidimensional supersymmetric quantum mechanics: spurious states for the tensor sector two Hamiltonian.

    PubMed

    Chou, Chia-Chun; Kouri, Donald J

    2013-04-25

    We show that there exist spurious states for the sector two tensor Hamiltonian in multidimensional supersymmetric quantum mechanics. For one-dimensional supersymmetric quantum mechanics on an infinite domain, the sector one and two Hamiltonians have identical spectra with the exception of the ground state of the sector one. For tensorial multidimensional supersymmetric quantum mechanics, there exist normalizable spurious states for the sector two Hamiltonian with energy equal to the ground state energy of the sector one. These spurious states are annihilated by the adjoint charge operator, and hence, they do not correspond to physical states for the original Hamiltonian. The Hermitian property of the sector two Hamiltonian implies the orthogonality between spurious and physical states. In addition, we develop a method for construction of a specific form of the spurious states for any quantum system and also generate several spurious states for a two-dimensional anharmonic oscillator system and for the hydrogen atom. PMID:23531015

  3. Mechanical Behavior of Grain Boundary Engineered Copper

    SciTech Connect

    Carter, S B; Hodge, A M

    2006-08-08

    A grain boundary engineered copper sample previously characterized by Electron Backscatter Diffraction (EBSD) has been selected for nanoindentation tests. Given the fact that grain boundaries have thicknesses in the order of 1 micron or less, it is essential to use nanomechanics to test the properties of individual grain boundaries. The Hysitron nanoindenter was selected over the MTS nanoindenter due to its superior optical capabilities that aid the selection and identification of the areas to be tested. An area of 2mm by 2mm with an average grain size of 50 microns has been selected for the study. Given the EBSD mapping, grains and grain boundaries with similar orientations are tested and the hardness and modulus are compared. These results will give a relationship between the mechanical properties and the engineered grain boundaries. This will provide for the first time a correlation between grain boundary orientation and the mechanical behavior of the sample at the nanoscale.

  4. Propulsion Mechanism of Catalytic Microjet Engines

    PubMed Central

    Fomin, Vladimir M.; Hippler, Markus; Magdanz, Veronika; Soler, Lluís; Sanchez, Samuel; Schmidt, Oliver G.

    2014-01-01

    We describe the propulsion mechanism of the catalytic microjet engines that are fabricated using rolled-up nanotech. Microjets have recently shown numerous potential applications in nanorobotics but currently there is a lack of an accurate theoretical model that describes the origin of the motion as well as the mechanism of self-propulsion. The geometric asymmetry of a tubular microjet leads to the development of a capillary force, which tends to propel a bubble toward the larger opening of the tube. Because of this motion in an asymmetric tube, there emerges a momentum transfer to the fluid. In order to compensate this momentum transfer, a jet force acting on the tube occurs. This force, which is counterbalanced by the linear drag force, enables tube velocities of the order of 100 μm/s. This mechanism provides a fundamental explanation for the development of driving forces that are acting on bubbles in tubular microjets. PMID:25177214

  5. Selective Guide to Literature on Mechanical Engineering. Engineering Literature Guides, Number 2.

    ERIC Educational Resources Information Center

    Franklin, Hugh Lockwood, Comp.

    Mechanical engineering has become highly interdisciplinary. It would not be possible to single out particular reference sources that are uniquely applicable to mechanical engineering. For the purpose of this guide, mechanical engineering deals with the generation, transmission and utilization of heat and mechanical power and with the production of…

  6. Balancing mechanism for reciprocating piston engine

    SciTech Connect

    Murata, N.; Ogino, T.

    1987-04-14

    This patent describes a balancing mechanism for a reciprocating piston internal combustion engine which includes a cylinder, a piston reciprocatable in the cylinder, a crankcase, a crankshaft mounted in the crankshaft, a crankpin connected to the piston, and a pair of crank arms bridging the crankshaft and crankpin. The crank arms and crankpin rotate with the crankshaft during operation and form a rotating mass. The balancing mechanism comprises at least one rotating counterweight attached to and rotating with the crankshaft, and eccentric journal means on the crankshaft adjacent the crank arms, rotating with the crankshaft. The journal means has an axis spaced to the side of the crankshaft axis which is opposite from the crankpin. The rotating counterweight and the eccentric journal means counterbalancing the rotating mass.

  7. Stirling engine control mechanism and method

    DOEpatents

    Dineen, John J.

    1983-01-01

    A reciprocating-to-rotating motion conversion and power control device for a Stirling engine includes a hub mounted on an offset portion of the output shaft for rotation relative to the shaft and for sliding motion therealong which causes the hub to tilt relative to the axis of rotation of the shaft. This changes the angle of inclination of the hub relative to the shaft axis and changes the axial stroke of a set of arms connected to the hub and nutating therewith. A hydraulic actuating mechanism is connected to the hub for moving its axial position along the shaft. A balancing wheel is linked to the hub and changes its angle of inclination as the angle of inclination of the hub changes to maintain the mechanism in perfect balance throughout its range of motion.

  8. 46 CFR 12.15-13 - Deck engine mechanic.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY MERCHANT MARINE OFFICERS AND SEAMEN REQUIREMENTS FOR RATING ENDORSEMENTS Qualified Member of the Engine Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck...

  9. 2dF mechanical engineering

    NASA Astrophysics Data System (ADS)

    Smith, Greg; Lankshear, Allan

    1998-07-01

    2dF is a multi-object instrument mounted at prime focus at the AAT capable of spectroscopic analysis of 400 objects in a single 2 degree field. It also prepares a second 2 degree 400 object field while the first field is being observed. At its heart is a high precision robotic positioner that places individual fiber end magnetic buttons on one of two field plates. The button gripper is carried on orthogonal gantries powered by linear synchronous motors and contains a TV camera which precisely locates backlit buttons to allow placement in user defined locations to 10 (mu) accuracy. Fiducial points on both plates can also be observed by the camera to allow repeated checks on positioning accuracy. Field plates rotate to follow apparent sky rotation. The spectrographs both analyze light from the 200 observing fibers each and back- illuminate the 400 fibers being re-positioned during the observing run. The 2dF fiber position and spectrograph system is a large and complex instrument located at the prime focus of the Anglo Australian Telescope. The mechanical design has departed somewhat from the earlier concepts of Gray et al, but still reflects the audacity of those first ideas. The positioner is capable of positioning 400 fibers on a field plate while another 400 fibers on another plate are observing at the focus of the telescope and feeding the twin spectrographs. When first proposed it must have seemed like ingenuity unfettered by caution. Yet now it works, and works wonderfully well. 2dF is a system which functions as the result of the combined and coordinated efforts of the astronomers, the mechanical designers and tradespeople, the electronic designers, the programmers, the support staff at the telescope, and the manufacturing subcontractors. The mechanical design of the 2dF positioner and spectrographs was carried out by the mechanical engineering staff of the AAO and the majority of the manufacture was carried out in the AAO workshops.

  10. Marine Engine Mechanics. Performance Objectives. Intermediate Course.

    ERIC Educational Resources Information Center

    Jones, Marion

    Several intermediate performance objectives and corresponding criterion measures are presented for each of ten terminal objectives for a two-semester course (3 hours daily). This 540-hour intermediate course includes advanced troubleshooting techniques on outboard marine engines, inboard-outboard marine engines, inboard marine engines, boat…

  11. Valve mechanism for an automotive engine

    SciTech Connect

    Ishii, N.

    1988-02-16

    A valve mechanism for an automotive engine having a rocker arm comprising a rocker arm member rocked by a cam and an actuating arm member operatively engaged with the rocker arm member for operating a stem of a valve is described comprising: a sleeve rotatably and slidably mounted on a rocker-arm shaft and having splines on a periphery thereof and a cylindrical portion adjacent the splines. The rocker arm member has splines and slidably engaged with the splines of the sleeve. The actuating arm member has splines corresponding to the splines of the sleeve and slidably engaged with the cylindrical portion of the sleeve at a disengagement position. A piston is slidably mounted on the rocker-arm shaft adjacent the sleeve; and hydraulic means are for applying oil to the piston so as to shift the sleeve to an engagement position to engage the splines thereof with the actuating arm member. A spring is provided between the cylindrical portion and a shaft holder for shifting the sleeve from the engagement position to the disengagement position; and stopping means hold the sleeve at the disengagement position and the engagement position respectively.

  12. Energy efficient engine pin fin and ceramic composite segmented liner combustor sector rig test report

    NASA Technical Reports Server (NTRS)

    Dubiel, D. J.; Lohmann, R. P.; Tanrikut, S.; Morris, P. M.

    1986-01-01

    Under the NASA-sponsored Energy Efficient Engine program, Pratt and Whitney has successfully completed a comprehensive test program using a 90-degree sector combustor rig that featured an advanced two-stage combustor with a succession of advanced segmented liners. Building on the successful characteristics of the first generation counter-parallel Finwall cooled segmented liner, design features of an improved performance metallic segmented liner were substantiated through representative high pressure and temperature testing in a combustor atmosphere. This second generation liner was substantially lighter and lower in cost than the predecessor configuration. The final test in this series provided an evaluation of ceramic composite liner segments in a representative combustor environment. It was demonstrated that the unique properties of ceramic composites, low density, high fracture toughness, and thermal fatigue resistance can be advantageously exploited in high temperature components. Overall, this Combustor Section Rig Test program has provided a firm basis for the design of advanced combustor liners.

  13. Promoting Evidence-Based Practice: Models and Mechanisms from Cross-Sector Review

    ERIC Educational Resources Information Center

    Nutley, Sandra; Walter, Isabel; Davies, Huw T. O.

    2009-01-01

    This article draws on both a cross-sector literature review of mechanisms to promote evidence-based practice and a specific review of ways of improving research use in social care. At the heart of the article is a discussion of three models of evidence-based practice: the research-based practitioner model, the embedded research model, and the…

  14. Trends in the Education and Training of Professional Mechanical Engineers.

    ERIC Educational Resources Information Center

    Institution of Mechanical Engineers, London (England).

    Twelve papers discussing problems encountered and solutions to them were presented at a symposium which brought together persons concerned with the training of professional mechanical engineers. At Session I, papers covered the need for broadly-based training and engineering practice, training requirements for engineers in the process industries,…

  15. Shift mechanism for engine starting apparatus

    SciTech Connect

    Colvin, J.A.; Colvill, R.G.; Smock, A.L.

    1986-04-01

    This patent describes a shift lever mechanism for translating axial movement of the plunger of a starter solenoid into axial movement of a pinion of an engine starting apparatus. This apparatus consists of, a starter solenoid having an axially shiftable plunger and a coil winding, a spring opposing pull-in movement of the plunger and a solenoid switch operated to a closed condition when the plunger is completely pulled-in, a shift lever actuator carried by the plunger for axial movement therewith. The actuator has a pair of spaced surfaces, a pivotally mounted shift lever one end of which is adapted to be coupled to the pinion. The opposite end of the shift lever has a pair of opposed shift lever surfaces that respectively engage the surfaces on the actuator. The actuator surfaces and the shift lever surfaces are substantially engaged when the shift lever is in an at rest postion. The surfaces on the shift lever are at different radial distances from the pivot point of the shift lever and are arranged relative to the surfaces on the actuator such that when the solenoid plunger pulls-in the surface on the shift lever that is at the greater radial distance from the pivot point is moved by a surface of the actuator and the other surface on the shift lever becomes separated by a predetermined amount from its cooperating surface on the actuator. The amount of separation is sufficient to allow the solenoid switch to be actuated to an open condition when the solenoid coil winding is deenergized and the spring shifts and plunger to reengage the separated surfaces.

  16. Mechanical Engineering Education and Its Challenges

    NASA Astrophysics Data System (ADS)

    Ow, C. S.; Kanan, M. M.

    2015-09-01

    The paper addresses historical development in Engineering Education in the country, its evolution till present day efforts toward the formation of Professional Engineers (PE). Of particular interest is the proposed recognition of more than one pathways towards PE Certification amongst member countries of the International Engineering Alliance (IEA). However, Engineering Education of Gen Y poses challenges at maintaining relevant benchmarks at the basic degree level. The widespread use of sophisticated software for simulation work in any undergraduate programme has its sacrifices with respect to emphasis on depth of knowledge. A definite mismatch between what is perceived by the educators and the actual performance of graduates had been identified in a forum and an employment survey conducted by the Institution of Engineers Malaysia (IEM). Suggestions as to how this can be addressed include the setting up of a Board of Educators to regulate the education industry.

  17. Wentworth Institute Mechanical Engineering Laboratory Manual. Laboratory Study Guide.

    ERIC Educational Resources Information Center

    Avakian, Harry; And Others

    This publication is a laboratory study guide designed for mechanical engineering students. All of the experiments (with the exception of experiment No. 1) contained in the Mechanical Engineering Laboratory Manual have been included in this guide. Brief theoretical backgrounds, examples and their solutions, charts, graphs, illustrations, and…

  18. 2. Photographic copy of engineering drawing showing mechanical systems in ...

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

    2. Photographic copy of engineering drawing showing mechanical systems in plan and sections of Test Stand 'E,' including tunnel entrance. California Institute of Technology, Jet Propulsion Laboratory, Plant Engineering 'Bldg. E-60 Mechanical, Solid Propellant Test Stand,' sheet E60/13-4, June 20, 1961. - Jet Propulsion Laboratory Edwards Facility, Test Stand E, Edwards Air Force Base, Boron, Kern County, CA

  19. Great expectations: private sector activity in tissue engineering, regenerative medicine, and stem cell therapeutics.

    PubMed

    Lysaght, Michael J; Jaklenec, Ana; Deweerd, Elizabeth

    2008-02-01

    This report draws upon data from a variety of sources to provide a detailed estimate of the current scope of private sector development and commercial activity in the aggregate field comprising tissue engineering, regenerative medicine, and stem cell therapeutics. Economic activity has grown a remarkable fivefold in the past 5 years. As of mid-2007 approximately 50 firms or business units with over 3000 employees offered commercial tissue-regenerative products or services with generally profitable annual sales in excess of $1.3 billion. Well over a million patients have been treated with these products. In addition, 110 development-stage companies with over 55 products in FDA-level clinical trials and other preclinical stages employed approximately 2500 scientists or support personnel and spent 850 million development dollars in 2007. These totals represent a remarkable recovery from the downturn of 2000-2002, at which time tissue engineering was in shambles because of disappointing product launches, failed regulatory trials, and the general investment pullback following the dot-com crash. Commercial success has resulted in large measure from identification of products that are achievable with available technology and under existing regulatory guidelines. Development-stage firms have become much more adept at risk management. The resilience of the field, as well as its current breadth and diversity, augurs well for the future of regenerative medicine. PMID:18333783

  20. [Mechanisms of articulation between the informal and the formal urban sectors].

    PubMed

    Lomnitz, L

    1978-01-01

    This article utilizes field data from Mexico City squatter settlements and personal interviews with employers to analyze some aspects of social relations between the informal sector and the formal urban sector, and compares the results with findings of other anthropologists in Mexico and elsewhere to derive a series of theoretical generalizations concerning mechanisms of articulation between the marginal sector and the formal economic and political institutions of the society. The formal sector is postulated to consist of the 3 subsectors of power, capital, and labor, which are in permanent conflict among themselves but all of which enjoy labor security and an assured minimal level of income. The marginal or informal sector lacks employment security, a minimal income level, and bargaining power. It is characterized by a small scale economy utilizing intensive familial labor. The informal sector is marginal to the dominant industrial system of production and the state apparatus, although it fulfills functions in terms of the national economy. 2 types of relationships may be distinguished in the social organization of the marginal sector: reciprocal relations between equals which form a network for the exchange of goods and services, or patron/client relations which are used, for example, in the case of petty entrepreneurs utilizing their relatives and acquaintances to create units of production. The functions of reciprocal relations are affected by social, physical, economic, and psychosocial distance or proximity and may result in exchanges of information, labor assistance, loans, services, or moral support. Patron/client relations may be direct, or the "patron" may be an intermediary. Some reciprocal networks display a pattern of incipient asymmetry leading to formation of true patron/client ties and some petty entrepreneurs or intermediaries manage to develop true patron/client networks; case histories are used to illustrate both phenomena. Intermediaries

  1. Engineering Biosynthesis Mechanisms for Diversifying Polyhydroxyalkanoates.

    PubMed

    Chen, Guo-Qiang; Hajnal, Ivan; Wu, Hong; Lv, Li; Ye, Jianwen

    2015-10-01

    Polyhydroxyalkanoates (PHA) are a family of diverse biopolyesters synthesized by bacteria. PHA diversity, as reflected by its monomers, homopolymers, random and block copolymers, as well as functional polymers, can now be generated by engineering the three basic synthesis pathways including the acetoacetyl-CoA pathway, in situ fatty acid synthesis, and/or β-oxidation cycles, as well as PHA synthase specificity. It is now possible to tailor the PHA structures via genome editing or process engineering. The increasing PHA diversity and maturing PHA production technology should lead to more focused research into their low-cost and/or high-value applications. PMID:26409776

  2. Mathematical Building-Blocks in Engineering Mechanics

    ERIC Educational Resources Information Center

    Boyajian, David M.

    2007-01-01

    A gamut of mathematical subjects and concepts are taught within a handful of courses formally required of the typical engineering student who so often questions the relevancy of being bound to certain lower-division prerequisites. Basic classes at the undergraduate level, in this context, include: Integral and Differential Calculus, Differential…

  3. Marine Engine Mechanics. Performance Objectives. Basic Course.

    ERIC Educational Resources Information Center

    Jones, Marion

    Several intermediate performance objectives and corresponding criterion measures are presented for each of six terminal objectives for a two-semester course (2 hours daily) which provides training in the terminology, construction, and function of both two- and four-cycle fuel-air mixture internal combustion engines with emphasis on outboard marine…

  4. Formula Student as Part of a Mechanical Engineering Curriculum

    ERIC Educational Resources Information Center

    Davies, Huw Charles

    2013-01-01

    Formula Student (FS) is a multi-university student design competition managed by the UK Institution of Mechanical Engineers. Students are required to demonstrate and prove their creativity and engineering skills through the design, manufacture and financing of a small formula style race car. This paper seeks to explore the educational value that…

  5. 20. Photocopy of drawing (1961 mechanical drawing by Kaiser Engineers) ...

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

    20. Photocopy of drawing (1961 mechanical drawing by Kaiser Engineers) ELECTRICAL LAYOUTS FOR VEHICLE SUPPORT BUILDING, SHEET E-2 - Vandenberg Air Force Base, Space Launch Complex 3, Vehicle Support Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  6. The Stirling engine as a low cost tool to educate mechanical engineers

    SciTech Connect

    Gros, J.; Munoz, M.; Moreno, F.; Valero, A.

    1995-12-31

    The University of Zaragoza through CIRCE, the New Enterprise foundation, an Opel foundation and the local Government of Aragon have been developed a program to introduce the Stirling Engine as a low cost tool to educate students in mechanical engineering. The promotion of a prize like GNAT Power organized by the magazine Model Engineer in London, has improved the practical education of students in the field of mechanical devices and thermal engines. Two editions of the contest, 1993 and 1994, awarded the greatest power Stirling engine made by only using a little candle of paraffin as a heat source. Four engines were presented in the first edition, with an average power of about 100 mW, and seven engines in the second one, achieving a power of about 230 mW. Presentations in Technical Schools and the University have been carried out. Also low cost tools have been made for measuring an electronic device to draw the real internal pressure volume diagram using a PC. A very didactic software to design classic kinematic alpha, beta and gamma engines plus Ringbom beta and gamma engines has been created. A book is going to be published (in Spanish) explaining the design of small Stirling engines as a way to start with low cost research in thermal engines, a very difficult target with IC engines.

  7. Evolutionary mechanism as a template for protein engineering.

    PubMed

    Eisenbeis, Simone; Höcker, Birte

    2010-10-01

    The goal of a protein engineer is to adjust a protein to a specified new function. This is exactly what natural evolution has achieved many times. By studying evolutionary mechanisms, we can learn about ways to use the adaptability of proteins and to build new proteins. In fact, many techniques used in engineering are successfully mimicking evolutionary processes. We introduce the fundamental evolutionary mechanisms, take a closer look at duplication and fusion, recombination, and circular permutation and discuss their influence on protein engineering. Some important techniques are presented and illustrated with examples. PMID:20862721

  8. Welcoming speech from Dean Faculty of Mechanical Engineering, UMP

    NASA Astrophysics Data System (ADS)

    Taha, Zahari

    2012-09-01

    In the Name of Allah, the Most Beneficent, the Most Merciful. It is with great pleasure that I welcome the participants of the International Conference of Mechanical Engineering Research 2011. The Prophet Muhammad (peace be upon him) said 'Acquire knowledge and impart it to the people.' (Al Tirmidhi). The quest for knowledge has been from the beginning of time but knowledge only becomes valuable when it is disseminated and applied to benefit humankind. It is hoped that ICMER 2011 will be a platform to gather and disseminate the latest knowledge in mechanical engineering. Academicians, Scientist, Researchers and practitioners of mechanical engineering will be able to share and discuss new findings and applications of mechanical engineering. It is envisaged that the intellectual discourse will result in future collaborations between universities, research institutions and industry both locally and internationally. In particular it is expected that focus will be given to issues on environmental and energy sustainability. Researchers in the mechanical engineering faculty at UMP have a keen interest in technology to harness energy from the ocean. Lowering vehicle emissions has been a primary goal of researchers in the mechanical engineering faculty and the automotive engineering centre as well including developing vehicles using alternative fuels such as biodiesel and renewable sources such as solar driven electric vehicles. Finally I would like to congratulate the organizing committee for their tremendous efforts in organizing the conference. As I wrote this in the Holy Land of Makkah, I pray to Allah swt that the conference will be a success. Prof. Dr. Zahari Taha CEng, MIED, FASc Dean, Faculty of Mechanical Engineering Universiti Malaysia Pahang

  9. Portable mass spectrometer with one or more mechanically adjustable electrostatic sectors and a mechanically adjustable magnetic sector all mounted in a vacuum chamber

    DOEpatents

    Andresen, B.D.; Eckels, J.D.; Kimmons, J.F.; Martin, W.H.; Myers, D.W.; Keville, R.F.

    1992-10-06

    A portable mass spectrometer is described having one or more electrostatic focusing sectors and a magnetic focusing sector, all of which are positioned inside a vacuum chamber, and all of which may be adjusted via adjustment means accessible from outside the vacuum chamber. Mounting of the magnetic sector entirely within the vacuum chamber permits smaller magnets to be used, thus permitting reductions in both weight and bulk. 13 figs.

  10. Portable mass spectrometer with one or more mechanically adjustable electrostatic sectors and a mechanically adjustable magnetic sector all mounted in a vacuum chamber

    DOEpatents

    Andresen, Brian D.; Eckels, Joel D.; Kimmons, James F.; Martin, Walter H.; Myers, David W.; Keville, Robert F.

    1992-01-01

    A portable mass spectrometer is described having one or more electrostatic focusing sectors and a magnetic focusing sector, all of which are positioned inside a vacuum chamber, and all of which may be adjusted via adjustment means accessible from outside the vacuum chamber. Mounting of the magnetic sector entirely within the vacuum chamber permits smaller magnets to be used, thus permitting reductions in both weight and bulk.

  11. Engineering a General Education Program: Designing Mechanical Engineering General Education Courses

    ERIC Educational Resources Information Center

    Fagette, Paul; Chen, Shih-Jiun; Baran, George R.; Samuel, Solomon P.; Kiani, Mohammad F.

    2013-01-01

    The Department of Mechanical Engineering at our institution created two engineering courses for the General Education Program that count towards second level general science credit (traditional science courses are first level). The courses were designed for the general student population based upon the requirements of our General Education Program…

  12. Deconstructing Engineering Education Programmes: The DEEP Project to Reform the Mechanical Engineering Curriculum

    ERIC Educational Resources Information Center

    Busch-Vishniac, Ilene; Kibler, Tom; Campbell, Patricia B.; Patterson, Eann; Guillaume, Darrell; Jarosz, Jeffrey; Chassapis, Constantin; Emery, Ashley; Ellis, Glenn; Whitworth, Horace; Metz, Susan; Brainard, Suzanne; Ray, Pradosh

    2011-01-01

    The goal of the Deconstructing Engineering Education Programmes project is to revise the mechanical engineering undergraduate curriculum to make the discipline more able to attract and retain a diverse community of students. The project seeks to reduce and reorder the prerequisite structure linking courses to offer greater flexibility for…

  13. Bridging the Gap between Higher Education and the Telecommunications Engineering Sector

    ERIC Educational Resources Information Center

    Muhammad, Sajid Sheikh; Aurangzeb, Muhammad; Tarique, Imtiaz

    2009-01-01

    In this paper, the growth of the telecommunication sector in Pakistan and consequent development in the related professional education is studied. The widening gap between the telecommunication industry and associated education sector is identified. The higher educational programs in Pakistan have grown very rapidly to meet the needs of the…

  14. Cell Patterning for Liver Tissue Engineering via Dielectrophoretic Mechanisms

    PubMed Central

    Yahya, Wan Nurlina Wan; Kadri, Nahrizul Adib; Ibrahim, Fatimah

    2014-01-01

    Liver transplantation is the most common treatment for patients with end-stage liver failure. However, liver transplantation is greatly limited by a shortage of donors. Liver tissue engineering may offer an alternative by providing an implantable engineered liver. Currently, diverse types of engineering approaches for in vitro liver cell culture are available, including scaffold-based methods, microfluidic platforms, and micropatterning techniques. Active cell patterning via dielectrophoretic (DEP) force showed some advantages over other methods, including high speed, ease of handling, high precision and being label-free. This article summarizes liver function and regenerative mechanisms for better understanding in developing engineered liver. We then review recent advances in liver tissue engineering techniques and focus on DEP-based cell patterning, including microelectrode design and patterning configuration. PMID:24991941

  15. Sputtering. [as deposition technique in mechanical engineering

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1976-01-01

    This paper primarily reviews the potential of using the sputtering process as a deposition technique; however, the manufacturing and sputter etching aspects are also discussed. Since sputtering is not regulated by classical thermodynamics, new multicomponent materials can be developed in any possible chemical composition. The basic mechanism for dc and rf sputtering is described. Sputter-deposition is described in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter-etching, target geometry (coating complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also described are some of the specific industrial areas which are turning to sputter-deposition techniques.

  16. AN OVERVIEW OF THE SNS ACCELERATOR MECHANICAL ENGINEERING.

    SciTech Connect

    HSEUH, H.; LUDWIG, H.; MAHLER, G.; PAI, C.; PEARSON, C.; RANK, J.; TUOZZOLO, J.; WEI, J.

    2006-06-23

    The Spallation Neutron Source (SNS*) is an accelerator-based neutron source currently nearing completion at Oak Ridge National Laboratory. When completed in 2006, the SNS will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. SNS is a collaborative effort between six U.S. Department of Energy national laboratories and offered a unique opportunity for the mechanical engineers to work with their peers from across the country. This paper presents an overview of the overall success of the collaboration concentrating on the accelerator ring mechanical engineering along with some discussion regarding the relative merits of such a collaborative approach. Also presented are a status of the mechanical engineering installation and a review of the associated installation costs.

  17. Mechanical Architecture and Engineering of PAZ Instrument

    NASA Astrophysics Data System (ADS)

    Bautista Juzgado, Victor

    2012-07-01

    PAZ is a highly flexible X-Band Synthetic Aperture Radar satellite devoted to global Earth Observation. It fulfills the strategic needs of the Spanish Government within the National Earth Observation Program. This satellite will be capable of providing high quality SAR images up to very high resolution (e.g. meter and sub- meter). Its flexibility lies on the various instrument modes (Stripmap, ScanSAR, Sporlight...) with a wide number of configurations, both in left and right-looking scanning. The S/C will cover the Earth with a mean revisit time of 1 day taking around 200000 images per day over an area above 300000km2. In the frame of this program, EADS CASA Espacio (ECE) stands as satellite prime contractor as well as responsible for the design and development of the SAR instrument, also called Front End. This paper describes the mechanical architecture, driving requirements, analyses, tests and main challenges found during the Front End development at ECE from the structural point of view.

  18. High-performance computing in structural mechanics and engineering

    SciTech Connect

    Adeli, H.; Kamat, M.P.; Kulkarni, G.; Vanluchene, R.D. Georgia Inst. of Technology, Atlanta Montana State Univ., Bozeman )

    1993-07-01

    Recent advances in computer hardware and software have made multiprocessing a viable and attractive technology. This paper reviews high-performance computing methods in structural mechanics and engineering through the use of a new generation of multiprocessor computers. The paper presents an overview of vector pipelining, performance metrics for parallel and vector computers, programming languages, and general programming considerations. Recent developments in the application of concurrent processing techniques to the solution of structural mechanics and engineering problems are reviewed, with special emphasis on linear structural analysis, nonlinear structural analysis, transient structural analysis, dynamics of multibody flexible systems, and structural optimization. 64 refs.

  19. 46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order...

  20. 46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order...

  1. 46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order...

  2. 46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order...

  3. 46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order...

  4. A High Throughput Mechanical Screening Device for Cartilage Tissue Engineering

    PubMed Central

    Mohanraj, Bhavana; Hou, Chieh; Meloni, Greg R.; Cosgrove, Brian D.; Dodge, George R.; Mauck, Robert L.

    2014-01-01

    Articular cartilage enables efficient and near-frictionless load transmission, but suffers from poor inherent healing capacity. As such, cartilage tissue engineering strategies have focused on mimicking both compositional and mechanical properties of native tissue in order to provide effective repair materials for the treatment of damaged or degenerated joint surfaces. However, given the large number design parameters available (e.g. cell sources, scaffold designs, and growth factors), it is difficult to conduct combinatorial experiments of engineered cartilage. This is particularly exacerbated when mechanical properties are a primary outcome given the long time required for testing of individual samples. High throughput screening is utilized widely in the pharmaceutical industry to rapidly and cost-effectively assess the effects of thousands of compounds for therapeutic discovery. Here we adapted this approach to develop a high throughput mechanical screening (HTMS) system capable of measuring the mechanical properties of up to 48 materials simultaneously. The HTMS device was validated by testing various biomaterials and engineered cartilage constructs and by comparing the HTMS results to those derived from conventional single sample compression tests. Further evaluation showed that the HTMS system was capable of distinguishing and identifying ‘hits’, or factors that influence the degree of tissue maturation. Future iterations of this device will focus on reducing data variability, increasing force sensitivity and range, as well as scaling-up to even larger (96-well) formats. This HTMS device provides a novel tool for cartilage tissue engineering, freeing experimental design from the limitations of mechanical testing throughput. PMID:24275442

  5. PREFACE: 3rd International Conference of Mechanical Engineering Research (ICMER 2015)

    NASA Astrophysics Data System (ADS)

    Mamat, Riazalman; Rahman, Mustafizur; Mohd. Zuki Nik Mohamed, Nik; Che Ghani, Saiful Anwar; Harun, Wan Sharuzi Wan

    2015-12-01

    The 3rd ICMER2015 is the continuity of the NCMER2010. The year 2010 represents a significant milestone in the history for Faculty of Mechanical Engineering, Universiti Malaysia Pahang (UMP) Malaysia with the organization of the first and second national level conferences (1st and 2nd NCMER) at UMP on May 26-27 and Dec 3-4 2010. The Faculty then changed the name from National Conference on Mechanical Engineering Research (NCMER) to International Conference on Mechanical Engineering Research (ICMER) in 2011 and this year, 2015 is our 3rd ICMER. These proceedings contain the selected scientific manuscripts submitted to the conference. It is with great pleasure to welcome you to the "International Conference on Mechanical Engineering Research (ICMER2015)" that is held at Zenith Hotel, Kuantan, Malaysia. The call for papers attracted submissions of over two hundred abstracts from twelve different countries including Japan, Iran, China, Kuwait, Indonesia, Norway, Philippines, Morocco, Germany, UAE and more. The scientific papers published in these proceedings have been revised and approved by the technical committee of the 3rd ICMER2015. All of the papers exhibit clear, concise, and precise expositions that appeal to a broad international readership interested in mechanical engineering, combustion, metallurgy, materials science as well as in manufacturing and biomechanics. The reports present original ideas or results of general significance supported by clear reasoning and compelling evidence, and employ methods, theories and practices relevant to the research. The authors clearly state the questions and the significance of their research to theory and practice, describe how the research contributes to new knowledge, and provide tables and figures that meaningfully add to the narrative. In this edition of ICMER representatives attending are from academia, industry, governmental and private sectors. The plenary and invited speakers will present, discuss, promote and

  6. Evaluating Risk Awareness in Undergraduate Students Studying Mechanical Engineering

    ERIC Educational Resources Information Center

    Langdon, G. S.; Balchin, K.; Mufamadi, P.

    2010-01-01

    This paper examines the development of risk awareness among undergraduate students studying mechanical engineering at a South African university. A questionnaire developed at the University of Liverpool was modified and used on students from the first, second and third year cohorts to assess their awareness in the areas of professional…

  7. 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…

  8. Engine Fundamentals: Automotive Mechanics Instructional Program. Block 2.

    ERIC Educational Resources Information Center

    O'Brien, Ralph D.

    The second of six instructional blocks in automotive mechanics, the lessons and supportive information in the document provide a guide for teachers in planning an instructional program in engine fundamentals at the secondary and postsecondary level. The material, as organized, is a suggested sequence of instruction within each block. Each lesson…

  9. Analysis of the occupational, consumer and environmental exposure to engineered nanomaterials used in 10 technology sectors.

    PubMed

    Nowack, Bernd; Brouwer, Connie; Geertsma, Robert E; Heugens, Evelyn H W; Ross, Bryony L; Toufektsian, Marie-Claire; Wijnhoven, Susan W P; Aitken, Robert J

    2013-09-01

    Humans and the environment can come into contact with nanomaterials through a wide range of applications during all stages of the life cycle of nanoproducts. The aim of this commentary is to present an assessment of the potential for exposure and thus identify possible environmental, health and safety (EHS) issues for nanomaterials used in 10 technology sectors. We analysed all life cycle stages with regard to potential for exposure of workers, consumers/patients, and the environment. A wide variety of nanomaterials are used of which many have negligible potential for exposure, while others have medium or even high potential for exposure. Based on the likelihood of exposure, it appears that in general most attention should be paid to the agrifood, chemistry/materials, textiles and health sectors; and less to the information and communication technology (ICT), security and energy sectors. Toxicity and exposure are both important; however, the EHS impact of nanomaterials is always dependent on their particular use. PMID:22783888

  10. Operationalizing clean development mechanism baselines: A case study of China's electrical sector

    NASA Astrophysics Data System (ADS)

    Steenhof, Paul A.

    The global carbon market is rapidly developing as the first commitment period of the Kyoto Protocol draws closer and Parties to the Protocol with greenhouse gas (GHG) emission reduction targets seek alternative ways to reduce their emissions. The Protocol includes the Clean Development Mechanism (CDM), a tool that encourages project-based investments to be made in developing nations that will lead to an additional reduction in emissions. Due to China's economic size and rate of growth, technological characteristics, and its reliance on coal, it contains a large proportion of the global CDM potential. As China's economy modernizes, more technologies and processes are requiring electricity and demand for this energy source is accelerating rapidly. Relatively inefficient technology to generate electricity in China thereby results in the electrical sector having substantial GHG emission reduction opportunities as related to the CDM. In order to ensure the credibility of the CDM in leading to a reduction in GHG emissions, it is important that the baseline method used in the CDM approval process is scientifically sound and accessible for both others to use and for evaluation purposes. Three different methods for assessing CDM baselines and environmental additionality are investigated in the context of China's electrical sector: a method based on a historical perspective of the electrical sector (factor decomposition), a method structured upon a current perspective (operating and build margins), and a simulation of the future (dispatch analysis). Assessing future emission levels for China's electrical sector is a very challenging task given the complexity of the system, its dynamics, and that it is heavily influenced by internal and external forces, but of the different baseline methods investigated, dispatch modelling is best suited for the Chinese context as it is able to consider the important regional and temporal dimensions of its economy and its future development

  11. Fracture mechanics criteria for turbine engine hot section components

    NASA Technical Reports Server (NTRS)

    Meyers, G. J.

    1982-01-01

    The application of several fracture mechanics data correlation parameters to predicting the crack propagation life of turbine engine hot section components was evaluated. An engine survey was conducted to determine the locations where conventional fracture mechanics approaches may not be adequate to characterize cracking behavior. Both linear and nonlinear fracture mechanics analyses of a cracked annular combustor liner configuration were performed. Isothermal and variable temperature crack propagation tests were performed on Hastelloy X combustor liner material. The crack growth data was reduced using the stress intensity factor, the strain intensity factor, the J integral, crack opening displacement, and Tomkins' model. The parameter which showed the most effectiveness in correlation high temperature and variable temperature Hastelloy X crack growth data was crack opening displacement.

  12. 9. Photographic copy of engineering drawing showing the mechanical layout ...

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

    9. Photographic copy of engineering drawing showing the mechanical layout of Test Stand 'C' Cv Cell, vacuum line, and scrubber-condenser as erected in 1977-78. JPL drawing by VTN Consolidated, Inc. Engineers, Architects, Planners, 2301 Campus Drive, Irvine, California 92664: 'JPL-ETS E-18 (C-Stand Modifications) Control Elevations & Schematics,' sheet M-5 (JPL sheet number E18/44-0), 1 September 1977. - Jet Propulsion Laboratory Edwards Facility, Test Stand C, Edwards Air Force Base, Boron, Kern County, CA

  13. Microfabrication of hierarchical structures for engineered mechanical materials

    NASA Astrophysics Data System (ADS)

    Vera Canudas, Marc

    Materials found in nature present, in some cases, unique properties from their constituents that are of great interest in engineered materials for applications ranging from structural materials for the construction of bridges, canals and buildings to the fabrication of new lightweight composites for airplane and automotive bodies, to protective thin film coatings, amongst other fields. Research in the growing field of biomimetic materials indicates that the micro-architectures present in natural materials are critical to their macroscopic mechanical properties. A better understanding of the effect that structure and hierarchy across scales have on the material properties will enable engineered materials with enhanced properties. At the moment, very few theoretical models predict mechanical properties of simple materials based on their microstructures. Moreover these models are based on observations from complex biological systems. One way to overcome this challenge is through the use of microfabrication techniques to design and fabricate simple materials, more appropriate for the study of hierarchical organizations and microstructured materials. Arrays of structures with controlled geometry and dimension can be designed and fabricated at different length scales, ranging from a few hundred nanometers to centimeters, in order to mimic similar systems found in nature. In this thesis, materials have been fabricated in order to gain fundamental insight into the complex hierarchical materials found in nature and to engineer novel materials with enhanced mechanical properties. The materials fabricated here were mechanically characterized and compared to simple mechanics models to describe their behavior with the goal of applying the knowledge acquired to the design and synthesis of future engineered materials with novel properties.

  14. Innovative Mechanical Engineering Technologies, Equipment and Materials-2013

    NASA Astrophysics Data System (ADS)

    Ilnaz Izailovich, Fayrushin; Nail Faikovich, Kashapov; Mahmut Mashutovich, Ganiev

    2014-12-01

    In the period from 25 to 27 September 2013 the city of Kazan hosted the International Scientific Conference "Innovative mechanical engineering technologies, equipment and materials - 2013" (IRTC "IMETEM - 2013"). The conference was held on the grounds of "Kazanskaya Yarmarka" (Kazan). The conference plenary meeting was held with the participation of the Republic of Tatarstan, breakout sessions, forum "Improving the competitiveness and efficiency of engineering enterprises in the WTO" and a number of round tables. Traditionally, the event was followed by the 13th International specialized exhibition "Engineering. Metalworking. Kazan ", in which were presented the development of innovative enterprises in the interests of the Russian Federation of Industry of Republic of Tatarstan, to support the "Foundation for Assistance to Small Innovative Enterprises in Science and Technology" and the 8th specialized exhibition "TechnoWelding". Kashapov Nail, D.Sc., professor (Kazan Federal University)

  15. The World Health Organization's mechanisms for increasing the health sector budget: The South African context.

    PubMed

    Venter, Fouche Hendrik Johannes; Wolfaardt, Jaqueline Elizabeth

    2016-08-01

    South Africa (SA) has limited scope for raising income taxes, and the proposed National Health Insurance (NHI) scheme will necessitate growth in the health sector budget. The NHI White Paper suggests five funding scenarios to meet the expected shortfall. These scenarios are a mixture of a surcharge on taxable income, an increase in value-added tax and a payroll tax. Five alternative options, suggested by the World Health Organization, are interrogated as ways to decrease the general taxation proposed in the White Paper. The five mechanisms (corporate tax, financial transaction levy, and taxes on tobacco, alcohol and unhealthy foods) were chosen based on their fund-raising potential and their mandatory element. A literature review provides the information for a discussion of the potential costs of each mechanism. Within specific assumptions, potential budgetary contribution is compared with the requirement. First, raising corporate tax rates could raise enough funds, but the losses due to capital flight might be too much for the local economy to bear. Second, a levy on currency transactions is unlikely to raise the required resources, even without a probable decrease in the number of transactions. Third, the increase in the tax on tobacco and alcohol would need to be very large, even assuming that consumption patterns would remain unchanged. Lastly, a tax on unhealthy food products is a new idea and could be explored as an option - especially as the SA Treasury has announced its future implementation. Implementing only one of the mechanisms is unlikely to increase available funding sufficiently, but if they are implemented together the welfare-maximising tax rate for each mechanism may be high enough to fulfil the NHI scheme's budgetary requirement, moderating the increases in the tax burden of the SA population. PMID:27499398

  16. Interactive training model of TRIZ for mechanical engineers in China

    NASA Astrophysics Data System (ADS)

    Tan, Runhua; Zhang, Huangao

    2014-03-01

    Innovation is a process of taking an original idea and converting it into a business value, in which the engineers face some inventive problems which can be solved hardly by experience. TRIZ, as a new theory for companies in China, provides both conceptual and procedural knowledge for finding and solving inventive problems. Because the government plays a leading role in the diffusion of TRIZ, too many companies from different industries are waiting to be trained, but the quantity of the trainers mastering TRIZ is incompatible with that requirement. In this context, to improve the training effect, an interactive training model of TRIZ for the mechanical engineers in China is developed and the implementation in the form of training classes is carried out. The training process is divided into 6 phases as follows: selecting engineers, training stage-1, finding problems, training stage-2, finding solutions and summing up. The government, TRIZ institutions and companies to join the programs interact during the process. The government initiates and monitors a project in form of a training class of TRIZ and selects companies to join the programs. Each selected companies choose a few engineers to join the class and supervises the training result. The TRIZ institutions design the training courses and carry out training curriculum. With the beginning of the class, an effective communication channel is established by means of interview, discussion face to face, E-mail, QQ and so on. After two years training practices, the results show that innovative abilities of the engineers to join and pass the final examinations increased distinctly, and most of companies joined the training class have taken congnizance of the power of TRIZ for product innovation. This research proposes an interactive training model of TRIZ for mechanical engineers in China to expedite the knowledge diffusion of TRIZ.

  17. Something Old, Something New: Integrating Engineering Practice into the Teaching of Engineering Mechanics.

    ERIC Educational Resources Information Center

    Miller, Gregory R.; Cooper, Stephen C.

    1995-01-01

    Presents a multifaceted method for teaching engineering mechanics to satisfy several desiderata. This approach includes design projects, group work, basic competency exams, computational environments for simulating and visualizing phenomena, multimedia instructional tools, hands-on experiences, and student presentations. Describes the materials…

  18. Formula student as part of a mechanical engineering curriculum

    NASA Astrophysics Data System (ADS)

    Davies, Huw Charles

    2013-10-01

    Formula Student (FS) is a multi-university student design competition managed by the UK Institution of Mechanical Engineers. Students are required to demonstrate and prove their creativity and engineering skills through the design, manufacture and financing of a small formula style race car. This paper seeks to explore the educational value that derives from the FS activity through a series of semi-structured interviews with key stakeholders. Through the analysis of the interview data, it was found that the FS activity supported development of student skills and competencies in the following areas: use of engineering knowledge to support the application of existing and emerging technology; application of theoretical and practical knowledge to the solution of engineering problems; development of technical and commercial management skills; development of effective interpersonal skills, including communication skills; and demonstration of personal commitment to professional development. In addition, a number of areas for implementing 'good practise' have been identified. The information herein supports educators in their responsibility to help meet the needs of the engineering industry for high quality graduates.

  19. Commercial solar/load management experiment: New mechanical engineering building

    NASA Astrophysics Data System (ADS)

    Noble, J. M.

    1981-01-01

    The effects of load management heat recovery, thermal storage, and solar systems on energy usage and power demand profiles in the University of New Mexico's Mechanical Engineering Building are presented. Results were obtained from a year monitoring of the building's heating and cooling systems and recording of sensor signals by a computer based data acquisition system. A modified AXCESS Energy Analysis Program to simulate energy usage is detailed, and the development of perferred strategies for maximizing the building's load management capabilities is outlined.

  20. Multiscale Approach to Characterize Mechanical Properties of Tissue Engineered Skin.

    PubMed

    Tupin, S; Molimard, J; Cenizo, V; Hoc, T; Sohm, B; Zahouani, H

    2016-09-01

    Tissue engineered skin usually consist of a multi-layered visco-elastic material composed of a fibrillar matrix and cells. The complete mechanical characterization of these tissues has not yet been accomplished. The purpose of this study was to develop a multiscale approach to perform this characterization in order to link the development process of a cultured skin to the mechanical properties. As a proof-of-concept, tissue engineered skin samples were characterized at different stages of manufacturing (acellular matrix, reconstructed dermis and reconstructed skin) for two different aging models (using cells from an 18- and a 61-year-old man). To assess structural variations, bi-photonic confocal microscopy was used. To characterize mechanical properties at a macroscopic scale, a light-load micro-mechanical device that performs indentation and relaxation tests was designed. Finally, images of the internal network of the samples under stretching were acquired by combining confocal microscopy with a tensile device. Mechanical properties at microscopic scale were assessed. Results revealed that adding cells during manufacturing induced structural changes, which provided higher elastic modulus and viscosity. Moreover, senescence models exhibited lower elastic modulus and viscosity. This multiscale approach was efficient to characterize and compare skin equivalent samples and permitted the first experimental assessment of the Poisson's ratio for such tissues. PMID:26942585

  1. 49 CFR 173.220 - Internal combustion engines, self-propelled vehicles, mechanical equipment containing internal...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... vehicles, mechanical equipment containing internal combustion engines, and battery powered vehicles or... equipment containing internal combustion engines, and battery powered vehicles or equipment. (a... internal combustion engine, or a battery powered vehicle or equipment is subject to the requirements...

  2. Protein–Hydrogel Interactions in Tissue Engineering: Mechanisms and Applications

    PubMed Central

    Zustiak, Silviya P.; Wei, Yunqian

    2013-01-01

    Recent advances in our understanding of the sophistication of the cellular microenvironment and the dynamics of tissue remodeling during development, disease, and regeneration have increased our appreciation of the current challenges facing tissue engineering. As this appreciation advances, we are better equipped to approach problems in the biology and therapeutics of even more complex fields, such as stem cells and cancer. To aid in these studies, as well as the established areas of tissue engineering, including cardiovascular, musculoskeletal, and neural applications, biomaterials scientists have developed an extensive array of materials with specifically designed chemical, mechanical, and biological properties. Herein, we highlight an important topic within this area of biomaterials research, protein–hydrogel interactions. Due to inherent advantages of hydrated scaffolds for soft tissue engineering as well as specialized bioactivity of proteins and peptides, this field is well-posed to tackle major needs within emerging areas of tissue engineering. We provide an overview of the major modes of interactions between hydrogels and proteins (e.g., weak forces, covalent binding, affinity binding), examples of applications within growth factor delivery and three-dimensional scaffolds, and finally future directions within the area of hydrogel–protein interactions that will advance our ability to control the cell–biomaterial interface. PMID:23150926

  3. Mechanical stimulation improves tissue-engineered human skeletal muscle

    NASA Technical Reports Server (NTRS)

    Powell, Courtney A.; Smiley, Beth L.; Mills, John; Vandenburgh, Herman H.

    2002-01-01

    Human bioartificial muscles (HBAMs) are tissue engineered by suspending muscle cells in collagen/MATRIGEL, casting in a silicone mold containing end attachment sites, and allowing the cells to differentiate for 8 to 16 days. The resulting HBAMs are representative of skeletal muscle in that they contain parallel arrays of postmitotic myofibers; however, they differ in many other morphological characteristics. To engineer improved HBAMs, i.e., more in vivo-like, we developed Mechanical Cell Stimulator (MCS) hardware to apply in vivo-like forces directly to the engineered tissue. A sensitive force transducer attached to the HBAM measured real-time, internally generated, as well as externally applied, forces. The muscle cells generated increasing internal forces during formation which were inhibitable with a cytoskeleton depolymerizer. Repetitive stretch/relaxation for 8 days increased the HBAM elasticity two- to threefold, mean myofiber diameter 12%, and myofiber area percent 40%. This system allows engineering of improved skeletal muscle analogs as well as a nondestructive method to determine passive force and viscoelastic properties of the resulting tissue.

  4. 46 CFR 113.35-9 - Mechanical engine order telegraph systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine...

  5. 46 CFR 113.35-9 - Mechanical engine order telegraph systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine...

  6. 46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates...

  7. 46 CFR 113.35-9 - Mechanical engine order telegraph systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine...

  8. 46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates...

  9. 46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates...

  10. 46 CFR 113.35-9 - Mechanical engine order telegraph systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine...

  11. 46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates...

  12. 46 CFR 113.35-9 - Mechanical engine order telegraph systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine...

  13. 46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates...

  14. 49 CFR 176.905 - Motor vehicles or mechanical equipment powered by internal combustion engines.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... internal combustion engines. 176.905 Section 176.905 Transportation Other Regulations Relating to... engines. (a) A motor vehicle or any mechanized equipment powered by an internal combustion engine is... met: (1) The motor vehicle or mechanical equipment has an internal combustion engine using liquid...

  15. Mechanical-engineering aspects of mirror-fusion technology

    SciTech Connect

    Fisher, D.K.; Doggett, J.N.

    1982-07-15

    The mirror approach to magnetic fusion has evolved from the original simple mirror cell to today's mainline effort: the tandem-mirror machine with thermal barriers. Physics and engineering research is being conducted throughout the world, with major efforts in Japan, the USSR, and the US. At least one facility under construction (MFTF-B) will approach equivalent energy breakeven in physics performance. Significant mechanical engineering development is needed, however, before a demonstration reactor can be constructed. The principal areas crucial to mirror reactor development include large high-field superconducting magnets, high-speed continuous vacuum-pumping systems, long-pulse high-power neutral-beam and rf-plasma heating systems, and efficient high-voltage high-power direct converters. Other areas common to all fusion systems include tritium handling technology, first-wall materials development, and fusion blanket design.

  16. Health sector reforms and human resources for health in Uganda and Bangladesh: mechanisms of effect

    PubMed Central

    Ssengooba, Freddie; Rahman, Syed Azizur; Hongoro, Charles; Rutebemberwa, Elizeus; Mustafa, Ahmed; Kielmann, Tara; McPake, Barbara

    2007-01-01

    Background Despite the expanding literature on how reforms may affect health workers and which reactions they may provoke, little research has been conducted on the mechanisms of effect through which health sector reforms either promote or discourage health worker performance. This paper seeks to trace these mechanisms and examines the contextual framework of reform objectives in Uganda and Bangladesh, and health workers' responses to the changes in their working environments by taking a 'realistic evaluation' approach. Methods The study findings were generated by triangulating both qualitative and quantitative methods of data collection and analysis among policy technocrats, health managers and groups of health providers. Quantitative surveys were conducted with over 700 individual health workers in both Bangladesh and Uganda and supplemented with qualitative data obtained from focus group discussions and key interviews with professional cadres, health managers and key institutions involved in the design, implementation and evaluation of the reforms of interest. Results The reforms in both countries affected the workforce through various mechanisms. In Bangladesh, the effects of the unification efforts resulted in a power struggle and general mistrust between the two former workforce tracts, family planning and health. However positive effects of the reforms were felt regarding the changes in payment schemes. Ugandan findings show how the workforce responded to a strong and rapidly implemented system of decentralisation where the power of new local authorities was influenced by resource constraints and nepotism in recruitment. On the other hand, closer ties to local authorities provided the opportunity to gain insight into the operational constraints originating from higher levels that health staff were dealing with. Conclusion Findings from the study suggest that a) reform planners should use the proposed dynamic responses model to help design reform objectives

  17. Resources for startup and growing businesses in the science and engineering sectors

    NASA Astrophysics Data System (ADS)

    Sabol, Joseph

    2013-03-01

    The American Chemical Society provides resources for members involved in forming startup and growing small businesses in the chemical and related sectors. In particular, the ACS Division of Small Chemical Businesses SCHB provides member benefits, informative programming at national and regional meetings, and networking opportunities for entrepreneurs. SCHB member benefits include listing in a directory of members' products and services, discounted expo booth rental at ACS national meetings, sponsorship to attend ACS leadership development courses, volunteer opportunities to shape and direct SCHB's operations, multiple social networking platforms, and professional networking opportunities with like-minded and similarly situated small business principals. SCHB's mission is ``To aid in the formation, development and growth of small chemical businesses.'' SCHB collaborates with other units in ACS, including local sections, the Chemical Entrepreneurship Council, the Division of Business Development & Management, Entrepreneurial Initiative, and Career Services. SCHB helps chemists gain skills to translate research into commercially successful products; build strong, growing companies that create jobs; and collaborate with professionals outside the chemical community. American Chemical Society, Division of Small Chemical Businesses

  18. Quantitative ultrasonic evaluation of mechanical properties of engineering materials

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1978-01-01

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

  19. Interactive simulations as teaching tools for engineering mechanics courses

    NASA Astrophysics Data System (ADS)

    Carbonell, Victoria; Romero, Carlos; Martínez, Elvira; Flórez, Mercedes

    2013-07-01

    This study aimed to gauge the effect of interactive simulations in class as an active teaching strategy for a mechanics course. Engineering analysis and design often use the properties of planar sections in calculations. In the stress analysis of a beam under bending and torsional loads, cross-sectional properties are used to determine stress and displacement distributions in the beam cross section. The centroid, moments and products of inertia of an area made up of several common shapes (rectangles usually) may thus be obtained by adding the moments of inertia of the component areas (U-shape, L-shape, C-shape, etc). This procedure is used to calculate the second moments of structural shapes in engineering practice because the determination of their moments of inertia is necessary for the design of structural components. This paper presents examples of interactive simulations developed for teaching the ‘Mechanics and mechanisms’ course at the Universidad Politecnica de Madrid, Spain. The simulations focus on fundamental topics such as centroids, the properties of the moment of inertia, second moments of inertia with respect to two axes, principal moments of inertia and Mohr's Circle for plane stress, and were composed using Geogebra software. These learning tools feature animations, graphics and interactivity and were designed to encourage student participation and engagement in active learning activities, to effectively explain and illustrate course topics, and to build student problem-solving skills.

  20. Mechanism of cross-sectoral coordination between nature protection and forestry in the Natura 2000 formulation process in Slovakia.

    PubMed

    Sarvašová, Zuzana; Sálka, Jaroslav; Dobšinská, Zuzana

    2013-09-01

    Nature protection as a policy sector is not isolated and is directly or indirectly influenced by many other sectors (e.g. forestry, water management, rural development, energy, etc.). These policy sectors are neither completely segmented nor unaffected by the decisions taken in other policy sectors. Policy formulation in nature protection is therefore also influenced by different sectors. For that reason it is inevitable to stress the need for inter-sectoral coordination to assure their policy coherence. The aim of this article is to describe the mechanism and modes of cross-sectoral coordination and to analyze the relevant actors and their interaction, using the case of the Natura 2000 formulation process in Slovakia. The European Union (EU) set up an ecological network of special protected areas, known as Natura 2000 to ensure biodiversity by conserving natural habitats and wild fauna and flora in the territory of the Member States. An optimized nature protection must therefore carefully consider existing limits and crossdisciplinary relationships at the EU, national and regional levels. The relations between forestry and biodiversity protection are analyzed using the advocacy coalition framework (ACF). The ACF is used for analyzing how two coalitions, in this case ecological and forest owners' coalitions, advocate or pursue their beliefs from the nature protection and forestry policy field. The whole process is illustrated at the regional scale on the case study of Natura 2000 sites formulation in the Slovak Republic. For better reliability and validity of research, a combination of various empiric research methods was used, supported by existing theories. So called triangulation of sociological research or triangulation of methods consists of mutual results testing of individual methodological steps through identifying corresponding political-science theories, assessing their formal points using primary and secondary document analysis and assessing their

  1. Reservoir Engineering of Two-mode Correlations in Mechanical Resonators

    NASA Astrophysics Data System (ADS)

    Chang, Laura; Patil, Yogesh Sharad; Chakram, Srivatsan; Vengalattore, Mukund

    2015-05-01

    Nonlinear mechanical interactions in the quantum limit enable the manipulation and control of phonons in a manner akin to quantum optics in nonlinear media. We demonstrate, for the first time, strong quantum-compatible multimode nonlinearities in a low-loss mechanical resonator that is amenable to ground state optomechanical cooling, room temperature quantum control and quantum limited detection. These nonlinearities arise from substrate-mediated interactions between distinct modes of the resonator. We develop a model for this nonlinearity that accurately describes the experimental observations over three orders of magnitude in dynamic range, demonstrating the robustness and fidelity of the engineered nonlinear interactions. We use this nonlinearity to realize a mechanical nondegenerate parametric amplifier, and use it to demonstrate two-mode thermomechanical noise squeezing. Our work opens new opportunities for nonlinear approaches to quantum metrology, transduction between optical and phononic fields, and the quantum manipulation of phononic degrees of freedom. This work is supported by the DARPA QuASAR program through a grant from the ARO and an NSF INSPIRE award.

  2. Quantitative Ultrasonic Evaluation of Mechanical Properties of Engineering Materials

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1978-01-01

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

  3. Mechanical Control of Graphene on Engineered Pyramidal Strain Arrays.

    PubMed

    Gill, Stephen T; Hinnefeld, John H; Zhu, Shuze; Swanson, William J; Li, Teng; Mason, Nadya

    2015-06-23

    Strain can tune desirable electronic behavior in graphene, but there has been limited progress in controlling strain in graphene devices. In this paper, we study the mechanical response of graphene on substrates patterned with arrays of mesoscale pyramids. Using atomic force microscopy, we demonstrate that the morphology of graphene can be controlled from conformal to suspended depending on the arrangement of pyramids and the aspect ratio of the array. Nonuniform strains in graphene suspended across pyramids are revealed by Raman spectroscopy and supported by atomistic modeling, which also indicates strong pseudomagnetic fields in the graphene. Our results suggest that incorporating mesoscale pyramids in graphene devices is a viable route to achieving strain-engineering of graphene. PMID:25970764

  4. First Year Experiences in School of Mechanical Engineering Kanazawa University

    NASA Astrophysics Data System (ADS)

    Kinari, Toshiyasu; Kanjin, Yuichi; Furuhata, Toru; Tada, Yukio

    This paper reports two lectures of the first year experience, ‧Lecture on Life in Campus and Society‧ and ‧Freshman Seminar‧ and discusses their effects. Both lectures have been given freshmen of the school of mechanical engineering, Kanazawa University in H20 spring term. The former lecture is aimed at freshmen to keep on a proper way in both social and college life. It consists of normal class and e-learning system lectures. E-learning system examination requires students to review the whole text book and that seems to have brought better results in the survey. The latter seminar is aimed at freshmen to get active and self-disciplined learning way through their investigation, discussion, presentation, writing work, and so on.

  5. Critical Performance of Turbopump Mechanical Elements for Rocket Engine

    NASA Astrophysics Data System (ADS)

    Takada, Satoshi; Kikuchi, Masataka; Sudou, Takayuki; Iwasaki, Fumiya; Watanabe, Yoshiaki; Yoshida, Makoto

    It is generally acknowledged that bearings and axial seals have a tendency to go wrong compared with other rocket engine elements. And when those components have malfunction, missions scarcely succeed. However, fundamental performance (maximum rotational speed, minimum flow rate, power loss, durability, etc.) of those components has not been grasped yet. Purpose of this study is to grasp a critical performance of mechanical seal and hybrid ball bearing of turbopump. In this result, it was found that bearing outer race temperature and bearing coolant outlet temperature changed along saturation line of liquid hydrogen when flow rate was decreased under critical pressure. And normal operation of bearing was possible under conditions of more than 70,000 rpm of rotational speed and more than 0.2 liter/s of coolant flow rate. Though friction coefficient of seal surface increased several times of original value after testing, the seal showed a good performance same as before.

  6. 49 CFR 173.220 - Internal combustion engines, self-propelled vehicles, mechanical equipment containing internal...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... vehicles, mechanical equipment containing internal combustion engines, battery-powered equipment or... engines, self-propelled vehicles, mechanical equipment containing internal combustion engines, battery... battery-powered vehicle or equipment, or a fuel cell-powered vehicle or equipment, or any...

  7. 49 CFR 173.220 - Internal combustion engines, self-propelled vehicles, mechanical equipment containing internal...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... vehicles, mechanical equipment containing internal combustion engines, battery-powered equipment or... engines, self-propelled vehicles, mechanical equipment containing internal combustion engines, battery... battery-powered vehicle or equipment, or a fuel cell-powered vehicle or equipment, or any...

  8. 49 CFR 173.220 - Internal combustion engines, self-propelled vehicles, mechanical equipment containing internal...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... vehicles, mechanical equipment containing internal combustion engines, battery-powered equipment or... engines, self-propelled vehicles, mechanical equipment containing internal combustion engines, battery... battery-powered vehicle or equipment, or a fuel cell-powered vehicle or equipment, or any...

  9. 49 CFR 173.220 - Internal combustion engines, self-propelled vehicles, mechanical equipment containing internal...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... vehicles, mechanical equipment containing internal combustion engines, battery-powered equipment or... engines, self-propelled vehicles, mechanical equipment containing internal combustion engines, battery... battery-powered vehicle or equipment, or a fuel cell-powered vehicle or equipment, or any...

  10. Incorporating a Product Archaeology Paradigm across the Mechanical Engineering Curriculum

    ERIC Educational Resources Information Center

    Moore-Russo, Deborah; Cormier, Phillip; Lewis, Kemper; Devendorf, Erich

    2013-01-01

    Historically, the teaching of design theory in an engineering curriculum has been relegated to a senior capstone design experience. Presently, however, engineering design concepts and courses can be found through the entirety of most engineering programs. Educators have recognized that engineering design provides a foundational platform that can…

  11. Internal combustion engine and cam drive mechanism therefor

    SciTech Connect

    Ma, T.T.

    1986-03-25

    This patent describes a cam mechanism for driving the camshaft of a four-stroke internal combustion engine having one or more sets of n number of cylinders where n is a positive integer, a piston connected to a crankshaft and reciprocable in each cylinder and is either in phase or out of phase with any other piston in the set to which it belongs by a phase angle A/sup 0/, or an integral multiple thereof. A camshaft carries rotatable cams for actuating inlet and/or exhaust valves for each cylinder in the set. Characterized in the cam drive mechanism consist of means for rotating the camshaft with a rotational movement which is a combination of a circular motion about its axis of rotation which has a predetermined phase relationship with the circular movement of the crankshaft and an oscillatory motion about its axis of rotation to advance and retard the angular position of the cams relative to the valves with which they are associated. The oscillatory motion has a predetermined phase relationship with the crankshaft, and means for varying the amplitude of the oscillatory motion whereby the timing of the opening and closing of the valves may be varied, characterized in that the speed of the circular movement of the camshaft is half the speed of the crankshaft. The frequency of oscillations of the camshaft is f times the frequency of rotation of the crankshaft. The cam drive mechanism consists of a rotatable drive member drivable by the crankshaft. A connection is between the drive member and camshaft for transmitting the rotary motion of the drive member thereto. The connection including a sleeve element rotatable by the drive element and axially slidable relative thereto and having a helically splined connection with the camshaft whereby axial movement of the sleeve element effects a rotation of the camshaft relative to the drive member.

  12. Perspectives and Plans for Graduate Studies. 11. Engineering 1974. D. Mechanical Engineering. Report No. 74-21.

    ERIC Educational Resources Information Center

    Ontario Council on Graduate Studies, Toronto. Advisory Committee on Academic Planning.

    On the instruction of the Council of Ontario Universities, the Advisory Committee on Academic Planning in cooperation with the Committee of Ontario Deans of Engineering has conducted a planning assessment for doctoral work in mechanical engineering. This report presents as overview of the recommendations for each of the assessments conducted in…

  13. AUTOMOTIVE DIESEL MAINTENANCE 1. UNIT VI, MAINTAINING MECHANICAL GOVERNORS--DETROIT DIESEL ENGINES.

    ERIC Educational Resources Information Center

    Human Engineering Inst., Cleveland, OH.

    THIS MODULE OF A 30-MODULE COURSE IS DESIGNED TO DEVELOP AN UNDERSTANDING OF THE OPERATION AND MAINTENANCE OF MECHANICAL GOVERNORS USED ON DIESEL ENGINES. TOPICS ARE (1) TYPES OF GOVERNORS AND ENGINE LOCATION, (2) GOVERNOR APPLICATIONS, (3) LIMITING SPEED MECHANICAL GOVERNOR, (4) VARIABLE SPEED MECHANICAL GOVERNOR, AND (5) CONSTANT SPEED…

  14. Automotive Engines; Automotive Mechanics I: 9043.03.

    ERIC Educational Resources Information Center

    Dade County Public Schools, Miami, FL.

    This automotive engines course studies and demonstrates the theory and principles of operation of the automotive four stroke cycle engine. The student will develop an understanding of the systems necessary to make the engine perform as designed, such as cooling, fuel, ignition and lubrication. This is a one or two quinmester credit course of 45…

  15. Mechanical Design Engineering Enabler Project wheel and wheel drives

    NASA Technical Reports Server (NTRS)

    Nutt, Richard E.; Couch, Britt K.; Holley, John L., Jr.; Garris, Eric S.; Staut, Paul V.

    1992-01-01

    Our group was assigned the responsibility of designing the wheel and wheel drive system for a proof-of-concept model of the lunar-based ENABLER. ENABLER is a multi-purpose, six wheeled vehicle designed to lift and transport heavy objects associated with the construction of a lunar base. The resulting design was based on the performance criteria of the ENABLER. The drive system was designed to enable the vehicle to achieve a speed of 7 mph on a level surface, climb a 30 percent grade, and surpass a one meter high object and one meter wide crevice. The wheel assemblies were designed to support the entire weight of the vehicle on two wheels. The wheels were designed to serve as the main component of the vehicle's suspension and will provide suitable traction for lunar-type surfaces. The expected performance of the drive system for the ENABLER was influenced by many mechanical factors. The expected top speed on a level sandy surface is 4 mph instead of the desired 7 mph. This is due to a lack of necessary power at the wheels. The lack of power resulted from dimension considerations that allowed only an eight horsepower engine and also from mechanical inefficiencies of the hydraulic system. However, the vehicle will be able to climb a 30 percent grade, surpass a one meter high object and one meter wide crevice. The wheel assemblies will be able to support the entire weight of the vehicle on two wheels. The wheels will also provide adequate suspension for the vehicle and sufficient traction for lunar-type surfaces.

  16. Mechanical Engineering of the Linac for the Spallation Neutron Source

    SciTech Connect

    Bultman, N.K.; Chen, Z.; Collier, M.; Erickson, J.L.; Guthrie, A.; Hunter, W.T.; Ilg, T.; Meyer, R.K.; Snodgrass, N.L.

    1999-03-29

    The linac for the Spallation Neutron Source (SNS) Project will accelerate an average current of 1 mA of H{sup {minus}} ions from 20 MeV to 1GeV for injection into an accumulator ring. The linac will be an intense source of H{sup {minus}} ions and as such requires advanced design techniques to meet project technical goals as well as to minimize costs. The DTL, CCDTL and CCL are 466m long and operate at 805 MHz with a maximum H{sup {minus}} input current of 28 mA and 7% rf duty factor. The Drift Tube Linac is a copper-plated steel structure using permanent magnetic quadrupoles. The Coupled-Cavity portions are brazed copper structures and use electromagnetic quads. RF losses in the copper are 80 MW, with total rf power supplied by 52 klystrons. Additionally, the linac is to be upgraded to the 2- and 4-MW beam power levels with no increase in duty factor. The authors give an overview of the linac mechanical engineering effort and discuss the special challenges and status of the effort.

  17. Auto Mechanics I. Learning Activity Packets (LAPs). Section C--Engine.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains five learning activity packets (LAPs) that outline the study activities for the "engine" instructional area for an Auto Mechanics I course. The five LAPs cover the following topics: basic engine principles, cooling system, engine lubrication system, exhaust system, and fuel system. Each LAP contains a cover sheet that…

  18. Learning Activity Packets for Auto Mechanics II. Section A--Engine Rebuilding.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    Eight learning activity packets (LAPs) are provided for the instructional area of engine rebuilding in the auto mechanics II program. They accompany an instructor's guide available separately. The LAPs outline the study activities and performance tasks for these eight units: (1) engine condition evaluation; (2) engine removal; (3) engine…

  19. NASA GSFC Mechanical Engineering Latest Inputs for Verification Standards (GEVS) Updates

    NASA Technical Reports Server (NTRS)

    Kaufman, Daniel

    2003-01-01

    This viewgraph presentation provides information on quality control standards in mechanical engineering. The presentation addresses safety, structural loads, nonmetallic composite structural elements, bonded structural joints, externally induced shock, random vibration, acoustic tests, and mechanical function.

  20. A Review of Pacific Interdecadal Climate Variability: Possible Mechanisms and Surface Climate Signatures in the Pacific Sector

    NASA Astrophysics Data System (ADS)

    Mantua, N. J.

    2004-12-01

    Many investigators have examined historical surface climate records from the Pacific sector and identified a relatively small number of spatial patterns varying at decadal to interdecadal time scales. "Pacific Decadal Variability" (PDV) is a label that has been used to describe this family of climate variations. Some patterns of PDV are contained completely within the northern extratropics, while others have signatures throughout the Pacific hemisphere on both sides of the equator. Mechanisms for observed patterns of PDV are not yet known, though a wide variety of hypotheses have been proposed. Various ocean-atmosphere mechanisms for PDV are contained within the extratropics, others within the tropics, while others involve tropical-extratropical interactions. Some investigators have proposed external forcing (solar, lunar, or volcanic) as potentially important for driving PDV. A relatively simple hypothesis couples ENSO forcing with upper ocean heat storage for extratropical PDV, and it suggests PDV predictability may be limited to ~2 year lead times. Paleo-PDV reconstructions have been based on materials throughout the Pacific sector using such things as extratropical tree-rings, tropical corals, extratropical clam shell growth rings, and ice cores. These different proxy records have generally provided different perspectives on paleo-PDV behavior.

  1. Australian Apprentice & Trainee Statistics: Mechanical Engineering and Fabrication Trades, 1995-1999. Australian Vocational Education & Training.

    ERIC Educational Resources Information Center

    National Centre for Vocational Education Research, Leabrook (Australia).

    Statistics regarding Australians participating in apprenticeships and traineeships in the mechanical engineering and fabrication trades in 1995-1999 were reviewed to provide an indication of where skill shortages may be occurring or will likely occur in relation to the following occupations: mechanical engineering trades; fabrication engineering…

  2. Active Class Composed with Mechanical Engineering and Environment

    NASA Astrophysics Data System (ADS)

    Torii, Shuichi; Imamura, Yasuhiro; Ohshima, Yasutaka; Ariyoshi, Kouji

    This paper reports that the learning experience for a group working disassembling and assembling an internal combustion engine is constructed for a group working. At the same time, the environment education combined with basic studies is introduced with the aid of a Diesel engine running with biofuel. It is found that (1) the leaning experience enhances the leaning motivation and problem solution ability for students, (2) a group working disassembling and assembling an internal combustion engine is effective for greediness for learning, and (3) the environmental study attracts student.

  3. Manufacturing in Mechanical Engineering Education in Developing Countries.

    ERIC Educational Resources Information Center

    Peters, J.

    1989-01-01

    Discusses four problems which concern engineering education in developing countries: (1) less value of handiwork; (2) lack of industrial culture; (3) low salary of faculty; and (4) cultural distortions. Describes three successful cases in Indonesia and Thailand. (YP)

  4. Multi-project baselines for potential clean development mechanism projects in the electricity sector in South Africa

    SciTech Connect

    Winkler, H.; Spalding-Fecher, R.; Sathaye, J.; Price, L.

    2002-06-26

    The United Nations Framework Convention on Climate Change (UNFCCC) aims to reduce emissions of greenhouse gases (GHGs) in order to ''prevent dangerous anthropogenic interference with the climate system'' and promote sustainable development. The Kyoto Protocol, which was adopted in 1997 and appears likely to be ratified by 2002 despite the US withdrawing, aims to provide means to achieve this objective. The Clean Development Mechanism (CDM) is one of three ''flexibility mechanisms'' in the Protocol, the other two being Joint Implementation (JI) and Emissions Trading (ET). These mechanisms allow flexibility for Annex I Parties (industrialized countries) to achieve reductions by extra-territorial as well as domestic activities. The underlying concept is that trade and transfer of credits will allow emissions reductions at least cost. Since the atmosphere is a global, well-mixed system, it does not matter where greenhouse gas emissions are reduced. The CDM allows Annex I Parties to meet part of their emissions reductions targets by investing in developing countries. CDM projects must also meet the sustainable development objectives of the developing country. Further criteria are that Parties must participate voluntarily, that emissions reductions are ''real, measurable and long-term'', and that they are additional to those that would have occurred anyway. The last requirement makes it essential to define an accurate baseline. The remaining parts of section 1 outline the theory of baselines, emphasizing the balance needed between environmental integrity and reducing transaction costs. Section 2 develops an approach to multi-project baseline for the South African electricity sector, comparing primarily to near future capacity, but also considering recent plants. Five potential CDM projects are briefly characterized in section 3, and compared to the baseline in section 4. Section 5 concludes with a discussion of options and choices for South Africa regarding electricity

  5. Moist Teleconnection Mechanisms for the Tropical South American and Atlantic Sector*.

    NASA Astrophysics Data System (ADS)

    Neelin, J. David; Su, Hui

    2005-09-01

    Teleconnections have traditionally been studied for the case of dry dynamical response to a given diabatic heat source. Important anomalies often occur within convective zones, for instance, in the observed remote response to El Niño. The reduction of rainfall and teleconnection propagation in deep convective regions poses theoretical challenges because feedbacks involving convective heating and cloud radiative effects come into play. Land surface feedbacks, including variations of land surface temperature, and ocean surface layer temperature response must be taken into account. During El Niño, descent and negative precipitation anomalies often extend across equatorial South America and the Atlantic intertropical convergence zone. Analysis of simulated mechanisms in a case study of the 1997/98 El Niño is used to illustrate the general principals of teleconnections occurring in deep convective zones, contrasting land and ocean regions. Comparison to other simulated events shows similar behavior. Tropospheric temperature and wind anomalies are spread eastward by wave dynamics modified by interaction with the moist convection zones. The traditional picture would have gradual descent balanced by radiative damping, but this scenario misses the most important balances in the moist static energy (MSE) budget. A small “zoo” of mechanisms is active in producing strong regional descent anomalies and associated drought. Factors common to several mechanisms include the role of convective quasi equilibrium (QE) in linking low-level moisture anomalies to free tropospheric temperature anomalies in a two-way interaction referred to as QE mediation. Convective heating feedbacks change the net static stability to a gross moist stability (GMS) M. The large cloud radiative feedback terms may be manipulated to appear as a modified static stability Meff, under approximations that are quantified for the quasi-equilibrium tropical circulation model used here. The relevant measure

  6. Moist Teleconnection Mechanisms for the Tropical South American and Atlantic Sector*.

    NASA Astrophysics Data System (ADS)

    Neelin, J. David; Su, Hui

    2005-09-01

    Teleconnections have traditionally been studied for the case of dry dynamical response to a given diabatic heat source. Important anomalies often occur within convective zones, for instance, in the observed remote response to El Niño. The reduction of rainfall and teleconnection propagation in deep convective regions poses theoretical challenges because feedbacks involving convective heating and cloud radiative effects come into play. Land surface feedbacks, including variations of land surface temperature, and ocean surface layer temperature response must be taken into account. During El Niño, descent and negative precipitation anomalies often extend across equatorial South America and the Atlantic intertropical convergence zone. Analysis of simulated mechanisms in a case study of the 1997/98 El Niño is used to illustrate the general principals of teleconnections occurring in deep convective zones, contrasting land and ocean regions. Comparison to other simulated events shows similar behavior. Tropospheric temperature and wind anomalies are spread eastward by wave dynamics modified by interaction with the moist convection zones. The traditional picture would have gradual descent balanced by radiative damping, but this scenario misses the most important balances in the moist static energy (MSE) budget. A small “zoo” of mechanisms is active in producing strong regional descent anomalies and associated drought. Factors common to several mechanisms include the role of convective quasi equilibrium (QE) in linking low-level moisture anomalies to free tropospheric temperature anomalies in a two-way interaction referred to as QE mediation. Convective heating feedbacks change the net static stability to a gross moist stability (GMS) M. The large cloud radiative feedback terms may be manipulated to appear as a modified static stability Meff, under approximations that are quantified for the quasi-equilibrium tropical circulation model used here. The relevant measure

  7. A Microstructurally Motivated Model of the Mechanical Behavior of Tissue Engineered Blood Vessels

    PubMed Central

    Dahl, Shannon L. M.; Vaughn, Megann E.; Hu, Jin-Jia; Driessen, Niels J. B.; Baaijens, Frank P. T.; Humphrey, Jay D.; Niklason, Laura E.

    2008-01-01

    Mechanical models have potential to guide the development and use of engineered blood vessels as well as other engineered tissues. This paper presents a microstructurally motivated, pseudoelastic, mechanical model of the biaxial mechanics of engineered vessels in the physiologic pressure range. The model incorporates experimentally measured densities and alignments of engineered collagen. Specifically, these microstructural and associated mechanical inputs were measured directly from engineered blood vessels that were cultured over periods of 5–7.5 weeks. To the best of our knowledge, this is the first successful application of either a phenomenological or a microstructurally motivated mechanical model to engineered vascular tissues. Model development revealed the need to use novel theoretical configurations to describe the strain history of engineered vessels. The constitutive equations developed herein suggested that collagen remodeled between 5 and 7.5 weeks during a 7.5-week culture period. This remodeling led to strain energies for collagen that differed with alignment, which likely resulted from undulations that varied with alignment. Finally, biaxial data emphasized that axial extensions increase stresses in engineered vessels in the physiologic pressure range, thereby providing a guideline for surgical use: engineered vessels should be implanted at appropriate axial extension to minimize adverse stress responses. PMID:18720007

  8. How the Timing of Climate Change Policy Affects Infrastructure Turnover in the Electricity Sector: Engineering, Economic and Policy Considerations

    NASA Astrophysics Data System (ADS)

    Izard, Catherine Finlay

    The electricity sector is responsible for producing 35% of US greenhouse gas (GHG) emissions. Estimates suggest that ideally, the electricity sector would be responsible for approximately 85% of emissions abatement associated with climate polices such as America's Clean Energy and Security Act (ACES). This is equivalent to ˜50% cumulative emissions reductions below projected cumulative business-as-usual (BAU) emissions. Achieving these levels of emissions reductions will require dramatic changes in the US electricity generating infrastructure: almost all of the fossil-generation fleet will need to be replaced with low-carbon sources and society is likely to have to maintain a high build rate of new capacity for decades. Unfortunately, the inertia in the electricity sector means that there may be physical constraints to the rate at which new electricity generating capacity can be built. Because the build rate of new electricity generating capacity may be limited, the timing of regulation is critical---the longer the U.S. waits to start reducing GHG emissions, the faster the turnover in the electricity sector must occur in order to meet the same target. There is a real, and thus far unexplored, possibility that the U.S. could delay climate change policy implementation for long enough that it becomes infeasible to attain the necessary rate of turnover in the electricity sector. This dissertation investigates the relationship between climate policy timing and infrastructure turnover in the electricity sector. The goal of the dissertation is to answer the question: How long can we wait before constraints on infrastructure turnover in the electricity sector make achieving our climate goals impossible? Using the Infrastructure Flow Assessment Model, which was developed in this work, this dissertation shows that delaying climate change policy increases average retirements rates by 200-400%, increases average construction rates by 25-85% and increases maximum construction

  9. Fast on-line identification of instantaneous mechanical losses in internal combustion engines

    NASA Astrophysics Data System (ADS)

    Cruz-Peragón, F.; Palomar, J. M.; Díaz, F. A.; Jiménez-Espadafor, F. J.

    2010-01-01

    A fast and easy procedure to evaluate instantaneous mechanical losses in internal combustion engines (appropriate to any multi-cylinder engine) has been developed. First, a performance measurement procedure to obtain losses in one cycle is conducted. Subsequently, they must be proportionally divided into all cylinders, even considering those with no combustion. Finally, a non-linear identification procedure is applied to determine the coefficients of the P- ω method for each cylinder. The methodology has been applied to a single-cylinder compression ignition engine, and to a three-cylinder spark ignition engine. The first engine allows the procedure to be validated by comparing results with those obtained using other established methodology. The second engine makes it possible to analyze the robustness of the method when it is applied to a multi-cylinder engine.

  10. Dynamic Mechanical and Nanofibrous Topological Combinatory Cues Designed for Periodontal Ligament Engineering

    PubMed Central

    Kim, Joong-Hyun; Kang, Min Sil; Eltohamy, Mohamed; Kim, Tae-Hyun; Kim, Hae-Won

    2016-01-01

    Complete reconstruction of damaged periodontal pockets, particularly regeneration of periodontal ligament (PDL) has been a significant challenge in dentistry. Tissue engineering approach utilizing PDL stem cells and scaffolding matrices offers great opportunity to this, and applying physical and mechanical cues mimicking native tissue conditions are of special importance. Here we approach to regenerate periodontal tissues by engineering PDL cells supported on a nanofibrous scaffold under a mechanical-stressed condition. PDL stem cells isolated from rats were seeded on an electrospun polycaprolactone/gelatin directionally-oriented nanofiber membrane and dynamic mechanical stress was applied to the cell/nanofiber construct, providing nanotopological and mechanical combined cues. Cells recognized the nanofiber orientation, aligning in parallel, and the mechanical stress increased the cell alignment. Importantly, the cells cultured on the oriented nanofiber combined with the mechanical stress produced significantly stimulated PDL specific markers, including periostin and tenascin with simultaneous down-regulation of osteogenesis, demonstrating the roles of topological and mechanical cues in altering phenotypic change in PDL cells. Tissue compatibility of the tissue-engineered constructs was confirmed in rat subcutaneous sites. Furthermore, in vivo regeneration of PDL and alveolar bone tissues was examined under the rat premaxillary periodontal defect models. The cell/nanofiber constructs engineered under mechanical stress showed sound integration into tissue defects and the regenerated bone volume and area were significantly improved. This study provides an effective tissue engineering approach for periodontal regeneration—culturing PDL stem cells with combinatory cues of oriented nanotopology and dynamic mechanical stretch. PMID:26989897

  11. Automatic compression adjusting mechanism for internal combustion engines

    NASA Technical Reports Server (NTRS)

    Akkerman, J. W. (Inventor)

    1983-01-01

    Means for controlling the compression pressure in an internal combustion engine having one or more cylinders and subject to widely varying power output requirements are provided. Received between each crank pin and connecting rod is an eccentric sleeve selectively capable of rotation about the crank pin and/or inside the rod and for latching with the rod to vary the effective length of the connecting rod and thereby the clearance volume of the engine. The eccentric normally rotates inside the connecting rod during the exhaust and intake strokes but a latching pawl carried by the eccentric is movable radially outwardly to latch the rod and eccentric together during the compression and power strokes. A control valve responds to intake manifold pressure to time the supply of hydraulic fluid to move the latch-pawl outwardly, varying the effective rod length to maintain a substantially optimum firing chamber pressure at all intake manifold pressures.

  12. Curriculum Development Based on the Big Picture Assessment of the Mechanical Engineering Program

    ERIC Educational Resources Information Center

    Sabri, Mohd Anas Mohd; Khamis, Nor Kamaliana; Tahir, Mohd Faizal Mat; Wahid, Zaliha; Kamal, Ahmad; Ihsan, Ariffin Mohd; Sulong, Abu Bakar; Abdullah, Shahrum

    2013-01-01

    One of the major concerns of the Engineering Accreditation Council (EAC) is the need for an effective monitoring and evaluation of program outcome domains that can be associated with courses taught under the Mechanical Engineering program. However, an effective monitoring method that can determine the results of each program outcome using Bloom's…

  13. Mechanical override for electronic fuel control on a piston engine

    SciTech Connect

    Jedrziewski, S.T.

    1987-02-17

    This patent describes an apparatus for controlling the throttle of a fuel burning engine from either a shaft powered by automatic fuel control equipment or by the translational motion of a manually positioned throttle lever. The apparatus is attached to the engine via a throttle shaft extending outwardly from the wall of the engine fuel-air metering system, the apparatus comprising: an outer housing shell having a generally cylindrical interior and a lever arm rigidly attached to and extending radially away from the periphery thereof, the lever end furthest from the periphery of the outer housing shell being pivotally connected to the manual throttle lever; an output spool mounted for rotation within one end of the outer housing shell, the output spool having an axial boring at its outermost end sized to receive and be secured to the throttle shaft. The inward facing end of the output spool is coaxially formed into a cup shaped annulus; and an input spool having a generally cylindrical shape, the input spool mounted for rotation within the second end of the outer housing shell, the innermost end of the input spool being sized to fit within the cup shaped annulus on the inward facing end of the output spool. The input spool has an axial boring at its outermost end sized to receive and be secured to a shaft powered by the automatic fuel control equipment.

  14. Prior Knowledge of Mechanics amongst First Year Engineering Students

    ERIC Educational Resources Information Center

    Clements, Dick

    2007-01-01

    In the last 25 years, A-level Mathematics syllabi have changed very considerably, introducing a broader range of application areas but reducing the previous emphasis on classical mechanics. This article describes a baseline survey undertaken to establish in detail the entry levels in mechanics for the cohort of students entering Engineering…

  15. Safety engineering: KTA code of practice. Lifting mechanisms in nuclear plant

    NASA Astrophysics Data System (ADS)

    Lifting mechanisms safety requirements are discussed in accordance with the present state of development of science and engineering for the protection of life, health, and assets against the dangers of nuclear energy and the ill effects of ionizing radiation.

  16. Using a new incentive mechanism to improve wastewater sector performance: the case study of Italy.

    PubMed

    De Gisi, Sabino; Petta, Luigi; Farina, Roberto; De Feo, Giovanni

    2014-01-01

    The system of "Service Objectives", introduced by the Italian National Strategic Framework 2007-2013, is an innovative results-oriented programme concerning 4 thematic areas (education, care for the elderly and children, management of municipal solid wastes and integrated water service) in which the Ministry of Economic Development and eight Southern Italy districts are involved. The system was initially associated to an incentive mechanism which provided subsidies for a total amount of EUR 3 billion from the national Underdeveloped Areas Fund, according to the achievement of specific targets set for 11 service indicators in 2013. The indicators used for the integrated water service refer to the efficiency in water supply service as well as the coverage of wastewater treatment service. The aim of the study is to describe the activities carried out in Italy by the ENEA Agency in order to define a new performance indicator for wastewater treatment service taking into account the appropriateness and efficiency of existing plants equipment and, consequently, evaluating economic incentives. The proposed procedure takes into account both wastewater treatment demand and quality of wastewater treatment service offered to citizens. Input data, provided by the National Institute of Statistics (ISTAT), were elaborated in order to define appropriate parameters, with a multi-criteria analysis being used to define the new performance indicator. The applicability of the proposed procedure was verified considering all the 8 Southern Italy and Island districts (Abruzzo, Molise, Campania, Apulia, Basilicata, Calabria, Sicily and Sardinia) involved in the programme. The obtained results show that the quality of municipal wastewater may influence the calculation of the incentive amount. The performance indicators defined in this work might be conveniently extended to other contexts similar to the assessed geographical area (Southern Italy and Islands). PMID:24291582

  17. Unraveled mechanism in silk engineering: Fast reeling induced silk toughening

    NASA Astrophysics Data System (ADS)

    Wu, Xiang; Liu, Xiang-Yang; Du, Ning; Xu, Gangqin; Li, Baowen

    2009-08-01

    We theoretically and experimentally study the mechanical response of silkworm and spider silks against stretching and the relationship with the underlying structural factors. It is found that the typical stress-strain profiles are predicted in good agreement with experimental measurements by implementing the "β-sheet splitting" mechanism we discovered and verified, primarily varying the secondary structure of protein macromolecules. The functions of experimentally observed structural factors responding to the external stress have been clearly addressed, and optimization of the microscopic structures to enhance the mechanical strength will be pointed out, beneficial to their biomedical and textile applications.

  18. A reduced mechanism for biodiesel surrogates with low temperature chemistry for compression ignition engine applications

    NASA Astrophysics Data System (ADS)

    Luo, Zhaoyu; Plomer, Max; Lu, Tianfeng; Som, Sibendu; Longman, Douglas E.

    2012-04-01

    Biodiesel is a promising alternative fuel for compression ignition (CI) engines. It is a renewable energy source that can be used in these engines without significant alteration in design. The detailed chemical kinetics of biodiesel is however highly complex. In the present study, a skeletal mechanism with 123 species and 394 reactions for a tri-component biodiesel surrogate, which consists of methyl decanoate, methyl 9-decanoate and n-heptane was developed for simulations of 3-D turbulent spray combustion under engine-like conditions. The reduction was based on an improved directed relation graph (DRG) method that is particularly suitable for mechanisms with many isomers, followed by isomer lumping and DRG-aided sensitivity analysis (DRGASA). The reduction was performed for pressures from 1 to 100 atm and equivalence ratios from 0.5 to 2 for both extinction and ignition applications. The initial temperatures for ignition were from 700 to 1800 K. The wide parameter range ensures the applicability of the skeletal mechanism under engine-like conditions. As such the skeletal mechanism is applicable for ignition at both low and high temperatures. Compared with the detailed mechanism that consists of 3299 species and 10806 reactions, the skeletal mechanism features a significant reduction in size while still retaining good accuracy and comprehensiveness. The validations of ignition delay time, flame lift-off length and important species profiles were also performed in 3-D engine simulations and compared with the experimental data from Sandia National Laboratories under CI engine conditions.

  19. A novel mechanism of insect resistance engineered into tobacco

    NASA Astrophysics Data System (ADS)

    Hilder, Vaughan A.; Gatehouse, Angharad M. R.; Sheerman, Suzanne E.; Barker, Richard F.; Boulter, Donald

    1987-11-01

    A major goal of plant genetic engineering is the introduction of agronomically desirable phenotypic traits into crop plants in situations where conventional breeding methods have been unsuccessful. One such target is enhanced resistance to insect pests which, in view of the estimated production losses world-wide and the heavy costs of protective treatments, is very important. We report here that a gene encoding a cowpea trypsin inhibitor, which has been shown to give some measure of field resistance to insect pests1, confers, when transferred to tobacco, enhanced resistance to this species' own herbivorous insect pests.

  20. Biomaterials-Based Strategies for the Engineering of Mechanically Active Soft Tissues

    PubMed Central

    Tong, Zhixiang; Jia, Xinqiao

    2012-01-01

    Load-bearing, mechanically active tissues are routinely subjected to non-linear mechanical deformations. Consequently, these tissues exhibit complex mechanical properties and unique tissue organizations. Successful engineering of mechanically active tissues relies on the integration of the mechanical sensing mechanism found in the native tissues into polymeric scaffolds. Intelligent biomaterials that closely mimic the structural organizations and multi-scale responsiveness of the natural extracellular matrices (ECM), when strategically combined with multipotent cells and dynamic culture devices that generate physiologically relevant physical forces, will lead to the creation of artificial tissues that are mechanically robust and biologically functional. PMID:25250199

  1. Quantum-mechanical Brayton engine working with a particle in a one-dimensional harmonic trap

    NASA Astrophysics Data System (ADS)

    Wang, H.

    2013-05-01

    Based on the quantum version of thermodynamic processes, a quantum-mechanical Brayton engine model has been established. Expressions for the power output and efficiency of the engine are derived. Some fundamental optimal relations and general performance characteristic curves of the cycle are obtained. Furthermore, we note that it is possible to resist the reduction in efficiency, caused by compression of the adiabatic process, by decreasing the amount of energy levels of the quantum system. The results obtained here will provide theoretical guidance for the design of some new quantum-mechanical engines.

  2. The International Congress of Mechanical Engineering and Agricultural Sciences - CIIMCA 2013

    NASA Astrophysics Data System (ADS)

    Remolina-Millán, Aduljay; Hernández-Arroyo, Emil

    2014-06-01

    The organizing committee of The International Congress of Mechanical Engineering and Agricultural Sciences - CIIMCA 2013 - are pleased to present CIIMCA-2013: the first international conference focused on subjects of materials science, mechanical engineering and renewable energy organized by Mechanical Engineering Faculty of the ''Universidad Pontificia Bolivariana'' in Bucaramanga, Colombia. This conference aims to be a place to produce discussions on whole topics of the congress, between the scientists of Colombia and the world. We strongly believe that knowledge is fundamental to the development of our countries. For that reason this multidisciplinary conference is looking forward to integrate engineering, agricultural science and nanoscience and nanotechnology to produce a synergy of this area of knowledge and to achieve scientific and technological developments. Agriculture is a very important topic for our conference; in Colombia, agricultural science needs more attention from the scientific community and the government. In the Faculty of Mechanical Engineering we are beginning to work on these issues to produce knowledge and improve the conditions in our country. The CIIMCA conference is a great opportunity to create interpersonal relationships and networks between scientists around the world. The interaction between scientists is very important in the process of the construction of knowledge. The general chairman encourages and invites you to make friends, relationships and participate strongly in the symposia and all program activities. PhD Aduljay Remolina-Millán Principal Chairman, International Mechanical Engineering and Agricultural Sciences Congress - CIIMCA Msc Emil Hernández-Arroyo Principal Chairman, International Mechanical Engineering and Agricultural Sciences Congress - CIIMCA Conference photograph Conference photograph 'Universidad Pontificia Bolivariana seccional Bucaramanga' host of the first International Mechanical Engineering and

  3. Bioinspired Reductionistic Peptide Engineering for Exceptional Mechanical Properties

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  4. Bioinspired Reductionistic Peptide Engineering for Exceptional Mechanical Properties

    PubMed Central

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

    2015-01-01

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

  5. A novel tissue-engineered trachea with a mechanical behavior similar to native trachea.

    PubMed

    Park, Jeong Hun; Hong, Jung Min; Ju, Young Min; Jung, Jin Woo; Kang, Hyun-Wook; Lee, Sang Jin; Yoo, James J; Kim, Sung Won; Kim, Soo Hyun; Cho, Dong-Woo

    2015-09-01

    A novel tissue-engineered trachea was developed with appropriate mechanical behavior and substantial regeneration of tracheal cartilage. We designed hollow bellows scaffold as a framework of a tissue-engineered trachea and demonstrated a reliable method for three-dimensional (3D) printing of monolithic bellows scaffold. We also functionalized gelatin sponge to allow sustained release of TGF-β1 for stimulating tracheal cartilage regeneration and confirmed that functionalized gelatin sponge induces cartilaginous tissue formation in vitro. A tissue-engineered trachea was then created by assembling chondrocytes-seeded functionalized gelatin sponges into the grooves of bellows scaffold and it showed very similar mechanical behavior to that of native trachea along with substantial regeneration of tracheal cartilage in vivo. The tissue-engineered trachea developed here represents a novel concept of tracheal substitute with appropriate mechanical behavior similar to native trachea for use in reconstruction of tracheal stenosis. PMID:26041482

  6. Stirling engine power control and motion conversion mechanism

    DOEpatents

    Marks, David T.

    1983-01-01

    A motion conversion device for converting between the reciprocating motion of the pistons in a Stirling engine and the rotating motion of its output shaft, and for changing the stroke and phase of the pistons, includes a lever pivoted at one end and having a cam follower at the other end. The piston rod engages the lever intermediate its ends and the cam follower engages a cam keyed to the output shaft. The lever pivot can be moved to change the length of the moment arm defined between the cam follower and the piston rod the change the piston stroke and force exerted on the cam, and the levers can be moved in opposite directions to change the phase between pistons.

  7. Stirling engine power control and motion conversion mechanism

    SciTech Connect

    Marks, D.T.

    1983-07-12

    A motion conversion device for converting between the reciprocating motion of the pistons in a Stirling engine and the rotating motion of its output shaft, and for changing the stroke and phase of the pistons, includes a lever pivoted at one end and having a cam follower at the other end. The piston rod engages the lever intermediate its ends and the cam follower engages a cam keyed to the output shaft. The lever pivot can be moved to change the length of the moment arm defined between the cam follower and the piston rod the change the piston stroke and force exerted on the cam, and the levers can be moved in opposite directions to change the phase between pistons. 3 figs.

  8. General Mechanical Repair. Minor Automotive Maintenance, Small Engine [Repair, and] Welding: Competency Test Package.

    ERIC Educational Resources Information Center

    Hamlin, Larry

    This document contains the competency test package for three sections of a general mechanical repair course: minor automotive maintenance, small engine mechanics, and welding. Following a list of the common essential elements for trade and industrial education, competency tests for the three sections are provided. Each test includes unit name,…

  9. Mechanical Engineering Safety Note PEPC Spreader Bar Assembly

    SciTech Connect

    Mason, D.

    2001-08-26

    The PEPC Spreader Bar Assembly consists of a spreader bar that will be attached to the PEPC Cell Housing or the Midplane Transportation Fixture during operation. While in use in the OAB (Optics Assembly Building), the Spreader Bar Assembly will be manipulated by the NOID (New Optics Insertion Device). The other critical components of the assembly are the three angular contact bearing swivels that attach the spreader bar to the lifting mechanism and the corner clamps which are used to capture the Cell Housing.

  10. Effective Work Experience: An Exploratory Study of Strategies and Lessons from the United Kingdom's Engineering Education Sector.

    ERIC Educational Resources Information Center

    Powell, Marcus

    2001-01-01

    Interviews with 34 engineering education representatives indicated that traditional "sandwich" programs of year-long industry placement are changing. The present market-oriented policy environment provides few incentives to develop effective work experience programs or industry-education linkages. (Contains 26 references.) (SK)

  11. Wear mechanism and wear prevention in coal-fueled diesel engines

    SciTech Connect

    Not Available

    1990-06-20

    The overall objective of this program is to develop the diesel engine and lubricant system design approach that has the highest probability for commercial acceptance. Several specific objectives can also be identified. These objectives include: Definition of the dominant wear mechanisms prevailing in coal-fueled diesel engines; Definition of the specific effect of each coal-related lube oil contaminant; Determination of the potential of traditional engine lubrication design approaches to either solve or mitigate the effects of the coal related lube oil contaminants; Evaluation of several different engine design approaches aimed specifically at preventing lube oil contamination or preventing damage due to lube oil contamination; and Presentation of the engine/lubricant system design determined to have the most potential.

  12. Mechanical engineers' handbook, energy and power. 3rd ed.

    SciTech Connect

    Myer Kutz

    2005-12-15

    In addition to chapters on thermophysical properties of fluids, fundamentals of fluid mechanics, thermodynamics, heat transfer, combustion, and furnaces, Book 4 of the Handbook features coverage of both conventional (gaseous and liquid fuels, coal, and nuclear) and alternative (solar, geothermal, and fuel cells) energy sources, plus chapters on power machinery, refrigeration and cryogenics, environmental issues, and thermal systems optimization. Much of the material in this book is new or extensively revised, including coverage of such topics as: Heat pipes; Wind turbines; Fuel cells; Thermal systems optimization; Combustion; Fans, blowers, compressors, and pumps; Indoor environmental control; and Fluid power. Chapters of particular interest are: Combustion by Eric Eddings; Furnaces by Carroll Cone; Gaseous fuels by Richard J. Reed; Coals, lignite, peat by James Keppeler; and Air pollution-control technologies by C.A. Miller.

  13. Engineering a Place for Women: A Study of How Departmental Climate Influences the Career Satisfaction of Female Mechanical Engineering Faculty Members

    ERIC Educational Resources Information Center

    Young, Monica J.

    2012-01-01

    The purpose of this mixed-methods study was to better understand how female mechanical engineering faculty members' career experiences in academia affect their satisfaction. Specifically, the research considered differences in satisfaction reported by female and male mechanical engineering faculty members in terms of: (a) departmental…

  14. Mechanical Objects and the Engineering Learner: An Experimental Study of How the Presence of Objects Affects Students' Performance on Engineering Related Tasks

    ERIC Educational Resources Information Center

    Bairaktarova, Diana N.

    2013-01-01

    People display varying levels of interaction with the mechanical objects in their environment; engineers in particular as makers and users of these objects display a higher level of interaction with them. Investigating the educational potential of mechanical objects in stimulating and supporting learning in engineering is warranted by the fact…

  15. Robot-based Learning : Toward Cultivation of Information Technology Skills for Mechanical Engineering Students

    NASA Astrophysics Data System (ADS)

    Hanajima, Naohiko; Yamashita, Mitsuhisa; Kazama, Toshiharu; Yuasa, Tomonori; Niida, Yoichi; Aizu, Yoshihisa; Hikita, Hiromitsu

    Today there is increasing development of products in which embedded microprocessors are installed in a wide variety of industrial fields including mechanical industries. Mechanical engineers will be asked to develop such embedded systems in the future. To educate mechanical engineering students who possess information technology skills, for five years we have offered practical classes in which the students build a mobile robot with an embedded microprocessor and compete in a robot-triathlon race. The students have an incentive to program their robot to finish the race. We call this style of learning “robot-based learning.” In this paper, we discuss the efficiency of and problems in our practical classes as derived from information gained in surveys. In addition, we verify how the engineering design abilities of the students are improved through their participation in these classes.

  16. Mechanical Self-Assembly of a Strain-Engineered Flexible Layer: Wrinkling, Rolling, and Twisting

    NASA Astrophysics Data System (ADS)

    Chen, Zi; Huang, Gaoshan; Trase, Ian; Han, Xiaomin; Mei, Yongfeng

    2016-01-01

    Self-shaping of curved structures, especially those involving flexible thin layers, is attracting increasing attention because of their broad potential applications in, e.g., nanoelectromechanical andmicroelectromechanical systems, sensors, artificial skins, stretchable electronics, robotics, and drug delivery. Here, we provide an overview of recent experimental, theoretical, and computational studies on the mechanical self-assembly of strain-engineered thin layers, with an emphasis on systems in which the competition between bending and stretching energy gives rise to a variety of deformations, such as wrinkling, rolling, and twisting. We address the principle of mechanical instabilities, which is often manifested in wrinkling or multistability of strain-engineered thin layers. The principles of shape selection and transition in helical ribbons are also systematically examined. We hope that a more comprehensive understanding of the mechanical principles underlying these rich phenomena can foster the development of techniques for manufacturing functional three-dimensional structures on demand for a broad spectrum of engineering applications.

  17. Engine

    SciTech Connect

    Shin, H.B.

    1984-02-28

    An internal combustion engine has a piston rack depending from each piston. This rack is connected to a power output shaft through a mechanical rectifier so that the power output shaft rotates in only one direction. A connecting rod is pivotally connected at one end to the rack and at the other end to the crank of a reduced function crankshaft so that the crankshaft rotates at the same angular velocity as the power output shaft and at the same frequency as the pistons. The crankshaft has a size, weight and shape sufficient to return the pistons back into the cylinders in position for the next power stroke.

  18. Microstructure engineering from metallic powder blends for enhanced mechanical properties

    NASA Astrophysics Data System (ADS)

    Langlois, P.; Fagnon, N.; Dirras, G.

    2010-07-01

    The present work focuses on the transformation of high-purity Ni powder blends of controlled volume fractions (40 and 60 %) of nanometre-sized (100 nm) and micrometre-sized (544 nm) particles into bulk samples as part of a strategy for producing ultrafine-grained materials usefully exhibiting both strength and ductility. The process involved cold isostatic pressing at 1.5 GPa and sintering. The resulting bulk samples had relative densities near 95 %, were texture-free, and exhibited two different grain size distributions with an average value of 600 ± 30 nm. The mechanical properties were investigated by compression and microhardness tests, both at room temperature, and compared to the behaviour of a sample processed from micrometre-sized powder only. Samples prepared from the blends exhibited high yield stresses of 440 and 550 MPa after compression, and they did sustain work hardening. Tests conducted before and after compression up to 50 % deformation showed the same relative amount of hardness increase around 20 %, which was three times lower than that of the monolithic sample for which a decrease of the average grain size close to 26 % was measured.

  19. Mechanism of neutrophil activation and toxicity elicited by engineered nanomaterials.

    PubMed

    Johnston, Helinor; Brown, David M; Kanase, Nilesh; Euston, Matthew; Gaiser, Birgit K; Robb, Calum T; Dyrynda, Elisabeth; Rossi, Adriano G; Brown, Euan R; Stone, Vicki

    2015-08-01

    The effects of nanomaterials (NMs) on biological systems, especially their ability to stimulate inflammatory responses requires urgent investigation. We evaluated the response of the human differentiated HL60 neutrophil-like cell line to NMs. It was hypothesised that NM physico-chemical characteristics would influence cell responsiveness by altering intracellular Ca2+ concentration [Ca2+]i and reactive oxygen species production. Cells were exposed (1.95-125 μg/ml, 24 h) to silver (Ag), zinc oxide (ZnO), titanium dioxide (TiO2), multi-walled carbon nanotubes (MWCNTs) or ultrafine carbon black (ufCB) and cytotoxicity assessed (alamar blue assay). Relatively low (TiO2, MWCNTs, ufCB) or high (Ag, ZnO) cytotoxicity NMs were identified. Sub-lethal impacts of NMs on cell function were investigated for selected NMs only, namely TiO2, Ag and ufCB. Only Ag stimulated cell activation. Within minutes, Ag stimulated an increase in [Ca2+]i (in Fura-2 loaded cells), and a prominent inward ion current (assessed by electrophysiology). Within 2-4 h, Ag increased superoxide anion release and stimulated cytokine production (MCP-1, IL-8) that was diminished by Ca2+ inhibitors or trolox. Light microscopy demonstrated that cells had an activated phenotype. In conclusion NM toxicity was ranked; Ag>ufCB>TiO2, and the battery of tests used provided insight into the mechanism of action of NM toxicity to guide future testing strategies. PMID:25962642

  20. Mechanical testing of hydrogels in cartilage tissue engineering: beyond the compressive modulus.

    PubMed

    Xiao, Yinghua; Friis, Elizabeth A; Gehrke, Stevin H; Detamore, Michael S

    2013-10-01

    Injuries to articular cartilage result in significant pain to patients and high medical costs. Unfortunately, cartilage repair strategies have been notoriously unreliable and/or complex. Biomaterial-based tissue-engineering strategies offer great promise, including the use of hydrogels to regenerate articular cartilage. Mechanical integrity is arguably the most important functional outcome of engineered cartilage, although mechanical testing of hydrogel-based constructs to date has focused primarily on deformation rather than failure properties. In addition to deformation testing, as the field of cartilage tissue engineering matures, this community will benefit from the addition of mechanical failure testing to outcome analyses, given the crucial clinical importance of the success of engineered constructs. However, there is a tremendous disparity in the methods used to evaluate mechanical failure of hydrogels and articular cartilage. In an effort to bridge the gap in mechanical testing methods of articular cartilage and hydrogels in cartilage regeneration, this review classifies the different toughness measurements for each. The urgency for identifying the common ground between these two disparate fields is high, as mechanical failure is ready to stand alongside stiffness as a functional design requirement. In comparing toughness measurement methods between hydrogels and cartilage, we recommend that the best option for evaluating mechanical failure of hydrogel-based constructs for cartilage tissue engineering may be tensile testing based on the single edge notch test, in part because specimen preparation is more straightforward and a related American Society for Testing and Materials (ASTM) standard can be adopted in a fracture mechanics context. PMID:23448091

  1. Model for the improvement of the quality of the formation in mechanical engineering, applied to industrial engineering

    NASA Astrophysics Data System (ADS)

    Martin Garcia, Raul

    This doctoral thesis is structured in six chapters, of which the five first are dedicated to the theoretical part, and the sixth and last one to the practical part. In the chapter first is analyzed the present situation of the public university from the point of view of the factors that affect to its general environment, emphasizing quality like an exigency for the success, mainly in its external slope of clients satisfaction. In the chapter second is studied engineering education at general level and in relation to the degrees of industrial engineering. It's pointed out the importance of Higher Engineering for Education Europe (H3E) Agency standards, for the accreditation of the degrees in the New Higher Education European Space. The chapter third is centered in the industrial engineering education at particular level, for the degrees distributed by the Higher Polytechnical School of Algeciras (University of Cadiz, Spain). It's considered the formation contributed by the area of knowledge of mechanical engineering to each one of these degrees, and the necessity to reorient this university product to the necessities of the clients (employers) of the next surroundings. The chapter fourth is dedicated to justify the necessity and utility of designing the Model as improvement tool, protagonist of this thesis. For it are analyzed other management models recognized, in their aspect related to the reorientation to the clients necessities, making clear their inadecuidad for such aim. In the chapter fifth is shown the design of the Model at general level, with the Methodology of performance and the resources for the diagnosis, like tool for reorienting the formation distributed by an general educational unit to the employers necessities. In the chapter sixth is developed the application of the Model, designed to orient the formation distributed particularly by the area of mechanical engineering (treated in the chapter third) to the necessities of the companies of its

  2. Mechanical Stretching for Tissue Engineering: Two-Dimensional and Three-Dimensional Constructs

    PubMed Central

    Riehl, Brandon D.; Park, Jae-Hong; Kwon, Il Keun

    2012-01-01

    Mechanical cell stretching may be an attractive strategy for the tissue engineering of mechanically functional tissues. It has been demonstrated that cell growth and differentiation can be guided by cell stretch with minimal help from soluble factors and engineered tissues that are mechanically stretched in bioreactors may have superior organization, functionality, and strength compared with unstretched counterparts. This review explores recent studies on cell stretching in both two-dimensional (2D) and three-dimensional (3D) setups focusing on the applications of stretch stimulation as a tool for controlling cell orientation, growth, gene expression, lineage commitment, and differentiation and for achieving successful tissue engineering of mechanically functional tissues, including cardiac, muscle, vasculature, ligament, tendon, bone, and so on. Custom stretching devices and lab-specific mechanical bioreactors are described with a discussion on capabilities and limitations. While stretch mechanotransduction pathways have been examined using 2D stretch, studying such pathways in physiologically relevant 3D environments may be required to understand how cells direct tissue development under stretch. Cell stretch study using 3D milieus may also help to develop tissue-specific stretch regimens optimized with biochemical feedback, which once developed will provide optimal tissue engineering protocols. PMID:22335794

  3. Mechatronics: the future of mechanical engineering; past, present, and a vision for the future

    NASA Astrophysics Data System (ADS)

    Ramasubramanian, M. K.

    2001-08-01

    Mechatronics is the synergistic integration of precision mechanical engineering, electronics, computational hardware and software in the design of products and processes. Mechatronics, the term coined in Japan in the '70s, has evolved to symbolize what mechanical design engineers do today worldwide. The revolutionary introduction of the microprocessor (or microcontroller) in the early '80s and ever increasing performance-cost ratio has changed the paradigm of mechanical design forever, and has broadened the original definition of mechatronics to include intelligent control and autonomous decision-making. Today, increasing number of new products is being developed at the intersection between traditional disciplines of Engineering, and Computer and Material Sciences. New developments in these traditional disciplines are being absorbed into mechatronics design at an ever-increasing pace. In this paper, a brief history of mechatronics, and several examples of this rapid adaptation of technologies into product design is presented. With the ongoing information technology revolution, especially in wireless communication, smart sensors design (enabled by MEMS technology), and embedded systems engineering, mechatronics design is going through another step change in capabilities and scope. The implications of these developments in mechatronics design in the near future are discussed. Finally, deficiencies in our engineering curriculum to address the needs of the industry to cope up with these rapid changes, and proposed remedies, will also be discussed.

  4. Multi-scale mechanical characterization of scaffolds for heart valve tissue engineering.

    PubMed

    Argento, G; Simonet, M; Oomens, C W J; Baaijens, F P T

    2012-11-15

    Electrospinning is a promising technology to produce scaffolds for cardiovascular tissue engineering. Each electrospun scaffold is characterized by a complex micro-scale structure that is responsible for its macroscopic mechanical behavior. In this study, we focus on the development and the validation of a computational micro-scale model that takes into account the structural features of the electrospun material, and is suitable for studying the multi-scale scaffold mechanics. We show that the computational tool developed is able to describe and predict the mechanical behavior of electrospun scaffolds characterized by different microstructures. Moreover, we explore the global mechanical properties of valve-shaped scaffolds with different microstructural features, and compare the deformation of these scaffolds when submitted to diastolic pressures with a tissue engineered and a native valve. It is shown that a pronounced degree of anisotropy is necessary to reproduce the deformation patterns observed in the native heart valve. PMID:22999107

  5. Molecularly engineered dual-crosslinked hydrogel with ultrahigh mechanical strength, toughness, and good self-recovery.

    PubMed

    Lin, Peng; Ma, Shuanhong; Wang, Xiaolong; Zhou, Feng

    2015-03-25

    A molecularly engineered dual-crosslinked hydrogel with extraordinary mechanical properties is reported. The hydrogel network is formed with both chemical crosslinking and acrylic-Fe(III) coordination; these, respectively, impart the elasticity and enhance the mechanical properties by effectively dissipating energy. The optimal hydrogel achieves a tensile stress of ca. 6 MPa at a large elongation ratio (>7 times), a toughness of 27 MJ m(-3) , and a stiffness of ca. 2 MPa, and has good self-recovery properties. PMID:25677412

  6. Reciprocating balance weight mechanism for a piston type internal combustion engine

    SciTech Connect

    Nivi, H.; Field, N.L. III

    1987-08-25

    A balancing mechanism is described for reducing the vibration of a piston type internal combustion engine having a crankshaft and a camshaft, the balancing mechanisms comprising one or more reciprocating balance weights, with each weight comprising an elongate body having a cam follower mounted at either end and with each weight being driven by two rotating cams with at least one of the cams being driven by either the crankshaft or the camshaft.

  7. Wear mechanism and wear prevention in coal-fueled diesel engines. Final report

    SciTech Connect

    Schwalb, J.A.; Ryan, T.W.

    1991-10-01

    Coal fueled diesel engines present unique wear problems in the piston ring/cylinder liner area because of their tendency to contaminate the lube-oil with high concentrations of highly abrasive particles. This program involved a series of bench-scale wear tests and engine tests designed to investigate various aspects of the ring/liner wear problem and to make specific recommendations to engine manufacturers as to how to alleviate these problems. The program was organized into tasks, designed to accomplish the following objectives: (1) define the predominant wear mechanisms causing accelerated wear in the ring/liner area; (2) investigate the effectiveness of traditional approaches to wear prevention to prevent wear in coal-fueled engines; (3) further refine information on the most promising approaches to wear prevention; (4) present detailed information and recommendations to engine manufacturers on the most promising approach to wear prevention; (5) present a final report covering the entire program; (6)complete engine tests with a coal-derived liquid fuel, and investigate the effects of the fuel on engine wear and emissions.

  8. Wear mechanism and wear prevention in coal-fueled diesel engines

    SciTech Connect

    Schwalb, J.A.; Ryan, T.W.

    1991-10-01

    Coal fueled diesel engines present unique wear problems in the piston ring/cylinder liner area because of their tendency to contaminate the lube-oil with high concentrations of highly abrasive particles. This program involved a series of bench-scale wear tests and engine tests designed to investigate various aspects of the ring/liner wear problem and to make specific recommendations to engine manufacturers as to how to alleviate these problems. The program was organized into tasks, designed to accomplish the following objectives: (1) define the predominant wear mechanisms causing accelerated wear in the ring/liner area; (2) investigate the effectiveness of traditional approaches to wear prevention to prevent wear in coal-fueled engines; (3) further refine information on the most promising approaches to wear prevention; (4) present detailed information and recommendations to engine manufacturers on the most promising approach to wear prevention; (5) present a final report covering the entire program; (6)complete engine tests with a coal-derived liquid fuel, and investigate the effects of the fuel on engine wear and emissions.

  9. Was Babbage's Analytical Engine intended to be a mechanical model of the mind?

    PubMed

    Green, Christopher D

    2005-02-01

    In the 1830s, Charles Babbage worked on a mechanical computer he dubbed the Analytical Engine. Although some people around Babbage described his invention as though it had authentic mental powers, Babbage refrained from making such claims. He does not, however, seem to have discouraged those he worked with from mooting the idea publicly. This article investigates whether (1) the Analytical Engine was the focus of a covert research program into the mechanism of mentality; (2) Babbage opposed the idea that the Analytical Engine had mental powers but allowed his colleagues to speculate as they saw fit; or (3) Babbage believed such claims to be fanciful, but cleverly used the publicity they engendered to draw public and political attention to his project. PMID:16021763

  10. Mechanically induced structural changes during dynamic compression of engineered cartilaginous constructs can potentially explain increases in bulk mechanical properties

    PubMed Central

    Nagel, Thomas; Kelly, Daniel J.

    2012-01-01

    Several studies on chondrocyte-seeded hydrogels in bioreactor culture report increased mechanical properties of mechanically loaded constructs compared with unloaded free swelling controls despite no significant differences in biochemical composition. One possible explanation is that changes in the collagen architecture of dynamically compressed constructs lead to improved mechanical properties. Collagen molecules are incorporated locally into the extracellular matrix with individual stress-free configurations and orientations. In this study, we computationally investigated possible influences of loading on the collagen architecture in chondrocyte-seeded hydrogels and their resulting mechanical properties. Both the collagen orientation and its stress-free configuration were hypothesized to depend on the local mechanical environment. Reorientation of the collagen network alone in response to dynamic compression leads to a prediction of constructs with lower compressive properties. In contrast, remodelling of the stress-free configuration of the collagen fibres was predicted to result in a more compacted tissue with higher swelling pressures and an altered pre-stressed state within the collagen network. Combining both mechanisms resulted in predictions of construct geometry and mechanical properties in agreement with experimental observations. This study provides support for the hypothesis that structural changes to the collagen network contribute to the enhanced mechanical properties of cartilaginous tissues engineered in bioreactors. PMID:21900321

  11. Engine Tune-up Service. Unit 2: Charging System. Student Guide. Automotive Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Richardson, Roger L.; Bacon, E. Miles

    This student guide is for Unit 2, Charging System, in the Engine Tune-Up Service portion of the Automotive Mechanics Curriculum. It deals with how to test the charging system. A companion review exercise book and posttests are available separately as CE 031 209-210. An introduction tells how this unit fits into the total tune-up service, defines…

  12. Engine Tune-up Service. Unit 6: Emission Control Systems. Student Guide. Automotive Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Bacon, E. Miles

    This student guide is for Unit 6, Emission Control Systems, in the Engine Tune-Up Service portion of the Automotive Mechanics Curriculum. It deals with inspecting, testing, and servicing an emission control system. A companion review exercise book and posttests are available separately as CE 031 221-222. An introduction tells how this unit fits…

  13. Assessing Cognitive Load Theory to Improve Student Learning for Mechanical Engineers

    ERIC Educational Resources Information Center

    Impelluso, Thomas J.

    2009-01-01

    A computer programming class for students of mechanical engineering was redesigned and assessed: Cognitive Load Theory was used to redesign the content; online technologies were used to redesign the delivery. Student learning improved and the dropout rate was reduced. This article reports on both attitudinal and objective assessment: comparing…

  14. Strategies for the Cooperation of Educational Institutions and Companies in Mechanical Engineering

    ERIC Educational Resources Information Center

    Kettunen, Juha

    2006-01-01

    Purpose: The purpose of this study is to analyse the strategic planning of the Centre for Mechanical Engineering, which is a joint venture of educational institutions and companies in Southwest Finland. Design/methodology/approach: The paper presents the strategies of focus and cost efficiency and how the selected strategies can be adjusted…

  15. Cam Design Projects in an Advanced CAD Course for Mechanical Engineers

    ERIC Educational Resources Information Center

    Ault, H. K.

    2009-01-01

    The objective of this paper is to present applications of solid modeling aimed at modeling of complex geometries such as splines and blended surfaces in advanced CAD courses. These projects, in CAD-based Mechanical Engineering courses, are focused on the use of the CAD system to solve design problems for applications in machine design, namely the…

  16. Effectiveness of Using a Video Game to Teach a Course in Mechanical Engineering

    ERIC Educational Resources Information Center

    Coller, B. D.; Scott, M. J.

    2009-01-01

    One of the core courses in the undergraduate mechanical engineering curriculum has been completely redesigned. In the new numerical methods course, all assignments and learning experiences are built around a video/computer game. Students are given the task of writing computer programs to race a simulated car around a track. In doing so, students…

  17. Engine Performance (Section B: Fuel and Exhaust Systems). Auto Mechanics Curriculum Guide. Module 3. Instructor's Guide.

    ERIC Educational Resources Information Center

    Rains, Larry

    This module is the third of nine modules in the competency-based Missouri Auto Mechanics Curriculum Guide. Six units cover: fuel supply systems; carburetion; carburetor service; gasoline engine electronic fuel injection; diesel fuel injection; and exhaust systems and turbochargers. Introductory materials include a competency profile and…

  18. Engine Performance (Section C: Emission Control Systems). Auto Mechanics Curriculum Guide. Module 3. Instructor's Guide.

    ERIC Educational Resources Information Center

    Rains, Larry

    This engine performance (emission control systems) module is one of a series of competency-based modules in the Missouri Auto Mechanics Curriculum Guide. Topics of this module's five units are: positive crankcase ventilation (PCV) and evaporative emission control systems; exhaust gas recirculation (EGR); air injection and catalytic converters;…

  19. 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…

  20. Engine Tune-Up Service. Unit 3: Primary Circuit. Student Guide. Automotive Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Bacon, E. Miles

    This student guide is for Unit 3, Primary Circuit, in the Engine Tune-Up Service portion of the Automotive Mechanics Curriculum. It deals with how to test the primary ignition circuit. A companion review exercise book and posttests are available separately as CE 031 212-213. An introduction tells how this unit fits into the total tune-up service,…

  1. The Faculty Perspective on Holistic and Systems Thinking in American and Australian Mechanical Engineering Programmes

    ERIC Educational Resources Information Center

    Kellam, N. N.; Maher, M. A.; Peters, W. H.

    2008-01-01

    This research effort examined current mechanical engineering educational programmes in America and Australia to determine the degree of holistic, systems thinking of each programme. Faculty from ten American universities and ten Australian universities participated in online surveys and interviews. Resulting data analysis and interpretation…

  2. General Mechanical Repair. Minor Automotive Maintenance, Small Engine [Repair, and] Welding: Student Manual.

    ERIC Educational Resources Information Center

    Hamlin, Larry

    This document is a student manual for a general mechanical repair course. Following a list of common essential elements of trade and industrial education, the manual is divided into three sections. The first section, on minor automotive maintenance, contains 13 units: automotive shop safety; engine principles; fuel system operation and repair;…

  3. Preliminary Assessment of the Emporium Model in a Redesigned Engineering Mechanics Course

    ERIC Educational Resources Information Center

    Rais-Rohani, Masoud; Walters, Andrew

    2014-01-01

    A lecture-based engineering mechanics course (Statics) is redesigned using the Emporium model. Whereas students study the material outside of class via asynchronous online delivery of the content and instructional videos, they do all the other activities (e.g., assignments, tests) either individually or in groups inside the classroom. Computer-…

  4. How Students Use Their Knowledge of Calculus in an Engineering Mechanics Course.

    ERIC Educational Resources Information Center

    Roddick, Cheryl Stitt

    This study investigated students' conceptual and procedural understanding of calculus within the context of an engineering mechanics course. Four traditional calculus students were compared with three students from one of the calculus reform projects, Calculus & Mathematica. Task-based interviews were conducted with each participant throughout the…

  5. Identifying and Investigating Difficult Concepts in Engineering Mechanics and Electric Circuits. Research Brief

    ERIC Educational Resources Information Center

    Streveler, Ruth; Geist, Monica; Ammerman, Ravel; Sulzbach, Candace; Miller, Ronald; Olds, Barbara; Nelson, Mary

    2007-01-01

    This study extends ongoing work to identify difficult concepts in thermal and transport science and measure students' understanding of those concepts via a concept inventory. Two research questions provided the focal point: "What important concepts in electric circuits and engineering mechanics do students find difficult to learn?"…

  6. Proceedings of the 6th international offshore mechanics and Arctic engineering symposium, Vol. 4

    SciTech Connect

    Lunardini, V.J.; Sinha, N.K.; Wang, Y.S.; Goff, R.D.

    1987-01-01

    This book presents the papers given at a conference on offshore platforms. Topics considered at the conference included spray ice islands, arctic structures and operations, arctic thermal and permafrost engineering, ice properties, offshore drilling, foundations, offshore exploration, crude oil storage facilities, thermosyphons, heat transfer, concretes, wave forces, and soil mechanics.

  7. Student Motivation in Low-Stakes Assessment Contexts: An Exploratory Analysis in Engineering Mechanics

    ERIC Educational Resources Information Center

    Musekamp, Frank; Pearce, Jacob

    2016-01-01

    The goal of this paper is to examine the relationship of student motivation and achievement in low-stakes assessment contexts. Using Pearson product-moment correlations and hierarchical linear regression modelling to analyse data on 794 tertiary students who undertook a low-stakes engineering mechanics assessment (along with the questionnaire of…

  8. General Mechanical Repair. Minor Automotive Maintenance, Small Engine [Repair, and] Welding: Curriculum Guide and Lesson Plans.

    ERIC Educational Resources Information Center

    Hamlin, Larry

    This document contains a curriculum guide and lesson plans for a general mechanical repair course with three sections: minor automotive maintenance, small engine repair, and welding. The curriculum guide begins with a matrix that relates the lesson plans to essential elements of math, science, language arts, and social studies and to Texas…

  9. Engine Tune-Up Service. Unit 5: Fuel and Carburetion Systems. Student Guide. Automotive Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Goodson, Ludy

    This student guide is for Unit 5, Fuel and Carburetion Systems, in the Engine Tune-Up Service portion of the Automotive Mechanics Curriculum. It deals with inspecting and servicing the fuel and carburetion systems. A companion review exercise book and posttests are available separately as CE 031 218-219. An introduction tells how this unit fits…

  10. Cell death induced by mechanical compression on engineered muscle results from a gradual physiological mechanism.

    PubMed

    Wu, Yabin; van der Schaft, Daisy W J; Baaijens, Frank P; Oomens, Cees W J

    2016-05-01

    Deep tissue injury (DTI), a type of pressure ulcer, arises in the muscle layers adjacent to bony prominences due to sustained mechanical loading. DTI presents a serious problem in the clinic, as it is often not visible until reaching an advanced stage. One of the causes can be direct mechanical deformation of the muscle tissue and cell. The mechanism of cell death induced by mechanical compression was studied using bio-artificial skeletal muscle tissues. Compression was applied by placing weights on top of the constructs. The morphological changes of the cytoskeleton and the phosphorylation of mitogen-activated protein kinases (MAPK) under compression were investigated. Moreover, inhibitors for each of the three major MAPK groups, p38, ERK, and JNK, were applied separately to look at their roles in the compression caused apoptosis and necrosis. The present study for the first time showed that direct mechanical compression activates MAPK phosphorylation. Compression also leads to a gradual destruction of the cytoskeleton. The percentage apoptosis is strongly reduced by p38 and JNK inhibitors down to the level of the unloaded group. This phenomenon could be observed up to 24h after initiation of compression. Therefore, cell death in bio-artificial muscle tissue caused by mechanical compression is primarily caused by a physiological mechanism, rather than through a physical mechanism which kills the cell directly. These findings reveal insight of muscle cell death under mechanical compression. Moreover, the result indicates a potential clinical solution to prevent DTI by pre-treating with p38 or/and JNK inhibitors. PMID:26961799

  11. Development and Validation of a Reduced Reaction Mechanism for Biodiesel-Fueled Engine Simulations- SAE 2008-01-1378

    SciTech Connect

    Brakora, Jessica L; Ra, Youngchul; Reitz, Rolf; McFarlane, Joanna; Daw, C Stuart

    2008-01-01

    In the present study a skeletal chemical reaction mechanism for biodiesel surrogate fuel was developed and validated for multi-dimensional engine combustion simulations. The reduced mechanism was generated from an existing detailed methyl butanoate oxidation mechanism containing 264 species and 1219 reactions. The reduction process included flux analysis, ignition sensitivity analysis, and optimization of reaction rate constants under constant volume conditions. The current reduced mechanism consists of 41 species and 150 reactions and gives predictions in excellent agreement with those of the comprehensive mechanism. In order to validate the mechanism under biodiesel-fueled engine conditions, it was combined with another skeletal mechanism for n-heptane oxidation. This combined reaction mechanism, ERC-Bio, contains 53 species and 156 reactions, which can be used for diesel/biodiesel blend engine simulations. Biodiesel-fueled engine operation was successfully simulated using the ERC-Bio mechanism.

  12. PREFACE: 1st International Conference on Mechanical Engineering Research 2011 (ICMER2011)

    NASA Astrophysics Data System (ADS)

    Abu Bakar, Rosli

    2012-09-01

    The year 2010 represented a significant milestone in the history of the Mechanical Engineering community with the organization of the first and second national level conferences (National Conference in Mechanical Engineering for Research, 1st and 2nd NCMER) at Universiti Malaysia Pahang on 26-27 May and 3-4 December 2010. The conferences attracted a large number of delegates from different premier academic and research institutions in the country to participate and share their research experiences at the conference. The International Conference on Mechanical Engineering Research (ICMER 2011) followed on from the first and second conferences due to good support from researchers. The ICMER 2011 is a good platform for researchers and postgraduate students to present their latest finding in research. The conference covers a wide range of topics including the internal combustion engine, machining processes, heat and mass transfer, fuel, biomechanical analysis, aerodynamic analysis, thermal comfort, computational techniques, design and simulation, automotive transmission, optimization techniques, hybrid electric vehicles, engine vibration, heat exchangers, finite element analysis, computational fluid dynamics, green energy, vehicle dynamics renewable energy, combustion, design, product development, advanced experimentation techniques, to name but a few. The international conference has helped to bridge the gap between researchers working at different institutions and in different countries to share their knowledge and has helped to motivate young scientists with their research. This has also given some clear direction for further research from the deliberations of the conference. Several people have contributed in different ways to the success of the conference. We thank the keynote speakers and all authors of the contributed papers, for the cooperation rendered to us in the publication of the CD conference proceedings. In particular, we would like to place on record our

  13. Mechanical objects and the engineering learner: An experimental study of how the presence of objects affects students' performance on engineering related tasks

    NASA Astrophysics Data System (ADS)

    Bairaktarova, Diana N.

    People display varying levels of interaction with the mechanical objects in their environment; engineers in particular as makers and users of these objects display a higher level of interaction with them. Investigating the educational potential of mechanical objects in stimulating and supporting learning in engineering is warranted by the fact that practicing engineers work with mechanical objects as they design, test and improve devices. It is possible that mechanical objects can facilitate learning by providing opportunities to authenticate the teaching and learning experience. More importantly, mechanical objects can serve as an instrument in transferring the knowledge of abstract concepts to practical applications. What remains unclear is how individual differences in interests and aptitudes are related to these interactions in engineering students. This study investigated how individual differences related to thing orientation and mechanical aptitude affect interaction with mechanical objects in engineering education instruction. The study introduces a task designed to replicate a real-world engineering application and uses this task to examine the effect of these aptitudes, interests, and direct manipulation of mechanical objects on performance.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    PubMed

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

    2016-07-21

    The mechanical properties of graphene oxide (GO) are of great importance for applications in materials engineering. Previous mechanochemical studies of GO typically focused on the influence of the degree of oxidation on the mechanical behavior. In this study, using density functional-based tight binding simulations, validated using density functional theory simulations, we reveal that the deformation and failure of GO are strongly dependent on the relative concentrations of epoxide (-O-) and hydroxyl (-OH) functional groups. Hydroxyl groups cause GO to behave as a brittle material; by contrast, epoxide groups enhance material ductility through a mechanically driven epoxide-to-ether functional group transformation. Moreover, with increasing epoxide group concentration, the strain to failure and toughness of GO significantly increases without sacrificing material strength and stiffness. These findings demonstrate that GO should be treated as a versatile, tunable material that may be engineered by controlling chemical composition, rather than as a single, archetypical material. PMID:27356465

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

    NASA Astrophysics Data System (ADS)

    Jiang, Jin-Wu

    2016-06-01

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

  17. Quiet Clean Short-haul Experimental Engine (QCSEE) Under-The-Wing (UTW) engine composite nacelle test report. Volume 1: Summary, aerodynamic and mechanical performance

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The performance test results of the final under-the-wing engine configuration are presented. One hundred and six hours of engine operation were completed, including mechanical and performance checkout, baseline acoustic testing with a bellmouth inlet, reverse thrust testing, acoustic technology tests, and limited controls testing. The engine includes a variable pitch fan having advanced composite fan blades and using a ball-spline pitch actuation system.

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

    PubMed

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

    2016-03-01

    Engineering of cartilage tissue in vitro using porous scaffolds and chondrocytes provides a promising approach for cartilage repair. However, nonuniform cell distribution and heterogeneous tissue formation together with weak mechanical property of in vitro engineered cartilage limit their clinical application. In this study, gelatin porous scaffolds with homogeneous and open pores were prepared using ice particulates and freeze-drying. The scaffolds were used to culture bovine articular chondrocytes to engineer cartilage tissue in vitro. The pore structure and mechanical property of gelatin scaffolds could be well controlled by using different ratios of ice particulates to gelatin solution and different concentrations of gelatin. Gelatin scaffolds prepared from ≥70% ice particulates enabled homogeneous seeding of bovine articular chondrocytes throughout the scaffolds and formation of homogeneous cartilage extracellular matrix. While soft scaffolds underwent cellular contraction, stiff scaffolds resisted cellular contraction and had significantly higher cell proliferation and synthesis of sulfated glycosaminoglycan. Compared with the gelatin scaffolds prepared without ice particulates, the gelatin scaffolds prepared with ice particulates facilitated formation of homogeneous cartilage tissue with significantly higher compressive modulus. The gelatin scaffolds with highly open pore structure and good mechanical property can be used to improve in vitro tissue-engineered cartilage. PMID:26650856

  19. Mathematical Modeling of Uniaxial Mechanical Properties of Collagen Gel Scaffolds for Vascular Tissue Engineering

    PubMed Central

    Irastorza, Ramiro M.; Drouin, Bernard; Blangino, Eugenia; Mantovani, Diego

    2015-01-01

    Small diameter tissue-engineered arteries improve their mechanical and functional properties when they are mechanically stimulated. Applying a suitable stress and/or strain with or without a cycle to the scaffolds and cells during the culturing process resides in our ability to generate a suitable mechanical model. Collagen gel is one of the most used scaffolds in vascular tissue engineering, mainly because it is the principal constituent of the extracellular matrix for vascular cells in human. The mechanical modeling of such a material is not a trivial task, mainly for its viscoelastic nature. Computational and experimental methods for developing a suitable model for collagen gels are of primary importance for the field. In this research, we focused on mechanical properties of collagen gels under unconfined compression. First, mechanical viscoelastic models are discussed and framed in the control system theory. Second, models are fitted using system identification. Several models are evaluated and two nonlinear models are proposed: Mooney-Rivlin inspired and Hammerstein models. The results suggest that Mooney-Rivlin and Hammerstein models succeed in describing the mechanical behavior of collagen gels for cyclic tests on scaffolds (with best fitting parameters 58.3% and 75.8%, resp.). When Akaike criterion is used, the best is the Mooney-Rivlin inspired model. PMID:25834840

  20. Mathematical modeling of uniaxial mechanical properties of collagen gel scaffolds for vascular tissue engineering.

    PubMed

    Irastorza, Ramiro M; Drouin, Bernard; Blangino, Eugenia; Mantovani, Diego

    2015-01-01

    Small diameter tissue-engineered arteries improve their mechanical and functional properties when they are mechanically stimulated. Applying a suitable stress and/or strain with or without a cycle to the scaffolds and cells during the culturing process resides in our ability to generate a suitable mechanical model. Collagen gel is one of the most used scaffolds in vascular tissue engineering, mainly because it is the principal constituent of the extracellular matrix for vascular cells in human. The mechanical modeling of such a material is not a trivial task, mainly for its viscoelastic nature. Computational and experimental methods for developing a suitable model for collagen gels are of primary importance for the field. In this research, we focused on mechanical properties of collagen gels under unconfined compression. First, mechanical viscoelastic models are discussed and framed in the control system theory. Second, models are fitted using system identification. Several models are evaluated and two nonlinear models are proposed: Mooney-Rivlin inspired and Hammerstein models. The results suggest that Mooney-Rivlin and Hammerstein models succeed in describing the mechanical behavior of collagen gels for cyclic tests on scaffolds (with best fitting parameters 58.3% and 75.8%, resp.). When Akaike criterion is used, the best is the Mooney-Rivlin inspired model. PMID:25834840

  1. Quiet Clean Short-haul Experimental Engine (QCSEE). Under-The-Wing (UTW) engine boilerplate nacelle test report. Volume 3: Mechanical performance

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Results of initial tests of the under the wing experimental engine and boilerplate nacelle are presented. The mechanical performance of the engine is reported with emphasis on the advanced technology components. Technology elements of the propulsion system covered include: system dynamics, composite fan blades, reduction gear, lube and accessory drive system, fan frame, inlet, core cowl cooling, fan exhaust nozzle, and digital control system.

  2. A triphasic constrained mixture model of engineered tissue formation under in vitro dynamic mechanical conditioning.

    PubMed

    Soares, Joao S; Sacks, Michael S

    2016-04-01

    While it has become axiomatic that mechanical signals promote in vitro engineered tissue formation, the underlying mechanisms remain largely unknown. Moreover, efforts to date to determine parameters for optimal extracellular matrix (ECM) development have been largely empirical. In the present work, we propose a two-pronged approach involving novel theoretical developments coupled with key experimental data to develop better mechanistic understanding of growth and development of dense connective tissue under mechanical stimuli. To describe cellular proliferation and ECM synthesis that occur at rates of days to weeks, we employ mixture theory to model the construct constituents as a nutrient-cell-ECM triphasic system, their transport, and their biochemical reactions. Dynamic conditioning protocols with frequencies around 1 Hz are described with multi-scale methods to couple the dissimilar time scales. Enhancement of nutrient transport due to pore fluid advection is upscaled into the growth model, and the spatially dependent ECM distribution describes the evolving poroelastic characteristics of the scaffold-engineered tissue construct. Simulation results compared favorably to the existing experimental data, and most importantly, distinguish between static and dynamic conditioning regimes. The theoretical framework for mechanically conditioned tissue engineering (TE) permits not only the formulation of novel and better-informed mechanistic hypothesis describing the phenomena underlying TE growth and development, but also the exploration/optimization of conditioning protocols in a rational manner. PMID:26055347

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

    PubMed

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

    2014-01-01

    A result of intervertebral disc (IVD) degeneration, the nucleus pulposus (NP) is no longer able to withstand applied load leading to pain and disability. The objective of this study is to fabricate a tissue-engineered injectable scaffold with chondroprotective supplementation in vitro to improve the mechanical properties of a degenerative NP. Tissue-engineered scaffolds were fabricated using different concentrations of alginate and calcium chloride and mechanically evaluated. Fabrication conditions were based on structural and mechanical resemblance to the native NP. Chondroprotective supplementation, glucosamine (GCSN) and chondroitin sulfate (CS), were added to scaffolds at concentrations of 0:0µg/mL (0:0-S), 125:100µg/mL (125:100-S), 250:200µg/mL (250:200-S), and 500:400µg/mL (500:400-S), GCSN and CS, respectively. Scaffolds were used to fabricate tissue-engineered constructs through encapsulation of human nucleus pulposus cells (HNPCs). The tissue-engineered constructs were collected at days 1, 14, and 28 for biochemical and biomechanical evaluations. Confocal microscopy showed HNPC viability and rounded morphology over the 28 day period. MTT analysis resulted in significant increases in cell proliferation for each group. Collagen type II ELISA quantification and compressive aggregate moduli (HA) showed increasing trends for both 250:200-S and the 500:400-S groups on Day 28 with significantly greater HA compared to 0:0-S group. Glycosaminoglycan and water content decreased for all groups. Results indicate the increased mechanical properties of the 250:200-S and the 500:400-S was due to production of a functional matrix. This study demonstrated potential for a chondroprotective supplemented injectable scaffold to restore biomechanical function of a degenerative disc through the production of a mechanically functional matrix. PMID:24055794

  4. Use of flow, electrical, and mechanical stimulation to promote engineering of striated muscles

    PubMed Central

    Rangarajan, Swathi; Madden, Lauran; Bursac, Nenad

    2014-01-01

    The field of tissue engineering involves design of high-fidelity tissue substitutes for predictive experimental assays in vitro and cell-based regenerative therapies in vivo. Design of striated muscle tissues, such as cardiac and skeletal muscle, has been particularly challenging due to a high metabolic demand and complex cellular organization and electromechanical function of the native tissues. Successful engineering of highly functional striated muscles may thus require creation of biomimetic culture conditions involving medium perfusion, electrical and mechanical stimulation. When optimized, these external cues are expected to synergistically and dynamically activate important intracellular signaling pathways leading to accelerated muscle growth and development. This review will discuss the use of different types of tissue culture bioreactors aimed at providing conditions for enhanced structural and functional maturation of engineered striated muscles. PMID:24366526

  5. PREFACE: International Scientific and Technical Conference ''Innovative Mechanical Engineering Technologies, Equipment and Materials-2014''

    NASA Astrophysics Data System (ADS)

    Nail, K.

    2015-06-01

    In the period from 3 to 5 December 2014 the city of Kazan hosted the International Scientific Conference ''Innovative mechanical engineering technologies, equipment and materials - 2014'' (ISC ''vIMETEM - 2014''). The event was followed by the 14th International specialized exhibition ''Engineering. Metalworking. Kazan'' The main objective of the annual conference was for participants to discuss scientific and technical achievements in the design and manufacture of engineering products, the expansion of cooperation between scientific organizations and enterprises of machine-building complex and the definition of perspective ways of creation and development of new techniques, technologies and materials. The conference ''IMETEM'' was devoted to the 90th anniversary of Fayzrahman Salahovich Yunusov, who made a great contribution in the field of aviation technology. Kashapov Nail, D.Sc., professor (Kazan Federal University)

  6. Design and analysis of tissue engineering scaffolds that mimic soft tissue mechanical anisotropy.

    PubMed

    Courtney, Todd; Sacks, Michael S; Stankus, John; Guan, Jianjun; Wagner, William R

    2006-07-01

    Tissue engineered constructs must exhibit tissue-like functional properties, including mechanical behavior comparable to the native tissues they are intended to replace. Moreover, the ability to reversibly undergo large strains can help to promote and guide tissue growth. Electrospun poly (ester urethane) ureas (ES-PEUU) are elastomeric and allow for the control of fiber diameter, porosity, and degradation rate. ES-PEUU scaffolds can be fabricated to have a well-aligned fiber network, which is important for applications involving mechanically anisotropic soft tissues. We have developed ES-PEUU scaffolds under variable speed conditions and modeled the effects of fiber orientation on the macro-mechanical properties of the scaffold. To illustrate the ability to simulate native tissue mechanical behavior, we demonstrated that the high velocity spun scaffolds exhibited highly anisotropic mechanical properties closely resembling the native pulmonary heart valve leaflet. Moreover, use of the present fiber-level structural constitutive model allows for the determination of electrospinning conditions to tailor ES-PEUU scaffolds for specific soft tissue applications. The results of this study will help to provide the basis for rationally designed mechanically anisotropic soft tissue engineered implants. PMID:16545867

  7. Design considerations and challenges for mechanical stretch bioreactors in tissue engineering.

    PubMed

    Lei, Ying; Ferdous, Zannatul

    2016-05-01

    With the increase in average life expectancy and growing aging population, lack of functional grafts for replacement surgeries has become a severe problem. Engineered tissues are a promising alternative to this problem because they can mimic the physiological function of the native tissues and be cultured on demand. Cyclic stretch is important for developing many engineered tissues such as hearts, heart valves, muscles, and bones. Thus a variety of stretch bioreactors and corresponding scaffolds have been designed and tested to study the underlying mechanism of tissue formation and to optimize the mechanical conditions applied to the engineered tissues. In this review, we look at various designs of stretch bioreactors and common scaffolds and offer insights for future improvements in tissue engineering applications. First, we summarize the requirements and common configuration of stretch bioreactors. Next, we present the features of different actuating and motion transforming systems and their applications. Since most bioreactors must measure detailed distributions of loads and deformations on engineered tissues, techniques with high accuracy, precision, and frequency have been developed. We also cover the key points in designing culture chambers, nutrition exchanging systems, and regimens used for specific tissues. Since scaffolds are essential for providing biophysical microenvironments for residing cells, we discuss materials and technologies used in fabricating scaffolds to mimic anisotropic native tissues, including decellularized tissues, hydrogels, biocompatible polymers, electrospinning, and 3D bioprinting techniques. Finally, we present the potential future directions for improving stretch bioreactors and scaffolds. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:543-553, 2016. PMID:26929197

  8. Methodological advances in predicting flow-induced dynamics of plants using mechanical-engineering theory.

    PubMed

    de Langre, Emmanuel

    2012-03-15

    The modeling of fluid-structure interactions, such as flow-induced vibrations, is a well-developed field of mechanical engineering. Many methods exist, and it seems natural to apply them to model the behavior of plants, and potentially other cantilever-like biological structures, under flow. Overcoming this disciplinary divide, and the application of such models to biological systems, will significantly advance our understanding of ecological patterns and processes and improve our predictive capabilities. Nonetheless, several methodological issues must first be addressed, which I describe here using two practical examples that have strong similarities: one from agricultural sciences and the other from nuclear engineering. Very similar issues arise in both: individual and collective behavior, small and large space and time scales, porous modeling, standard and extreme events, trade-off between the surface of exchange and individual or collective risk of damage, variability, hostile environments and, in some aspects, evolution. The conclusion is that, although similar issues do exist, which need to be exploited in some detail, there is a significant gap that requires new developments. It is obvious that living plants grow in and adapt to their environment, which certainly makes plant biomechanics fundamentally distinct from classical mechanical engineering. Moreover, the selection processes in biology and in human engineering are truly different, making the issue of safety different as well. A thorough understanding of these similarities and differences is needed to work efficiently in the application of a mechanistic approach to ecology. PMID:22357585

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

    PubMed Central

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

    2010-01-01

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

  10. [Mechanical strength and mechano-compatibility of tissue-engineered bones].

    PubMed

    Tanaka, Shigeo

    2016-01-01

    Current artificial bones made of metals and ceramics may be replaced around a decade after implantation due to its low durability, which is brought on by a large difference from the host bone in mechanical properties, i.e., low mechano-compatibility. On the other hand, tissue engineering could be a solution with regeneration of bone tissues from stem cells in vitro. However, there are still some problems to realize exactly the same mechanical properties as those of real bone. This paper introduces the technical background of bone tissue engineering and discusses possible methods for installation of mechano-compatibility into a regenerative bone. At the end, future directions toward the realization of ideal mechano-compatible regenerative bone are proposed. PMID:26728535

  11. Modeling of the thermo-mechanical efficiency of the bimetal strip heat engines

    NASA Astrophysics Data System (ADS)

    Arnaud, A.; Monfray, S.; Boughaleb, J.; Trioux, E.; Boeuf, F.; Cugat, O.; Skotnicki, T.

    2014-11-01

    This paper presents a theoretical demonstration of the bimetal strip heat engine working, based on the study of the thermo-mechanical instability of the pre-buckled bimetallic beams. Starting from the Euler buckling equation, this paper describes the bimetal strips like classical but non-linear thermodynamic systems, and gives the bistability criterion of such beams. Studying the thermodynamic potentials of these beams helps to evaluate the release of the kinetic energy happening during the beam snap-through, to give the Maxwell relations between each partial derivative of the thermodynamic potentials and to show that the thermal snap-through is a first-order transition according to the Ehrenfest theory. The model is then used to draw the temperature-entropy cycle of the bimetal heat engines and to evaluate the performances of these harvesters (available mechanical energy and thermodynamic cycle efficiency).

  12. Principles of construction of ultrasonic tomographs for solution of problems of nondestructive testing in mechanical engineering

    NASA Astrophysics Data System (ADS)

    Bolotina, I.; Bulavinov, A.; Pinchuk, R.; Salchak, Y.

    2016-04-01

    The paper considers the problems of ultrasonic nondestructive testing of products intended for mechanical engineering. The functional and electronic circuits of an ultrasonic tomograph are presented. The function of signal radiation from the clocked multielement apparatus is described, the cross-functional flowchart of the prototype of a US tomograph is considered. The development trends of ultrasonic tomography for near-term outlook are demonstrated.

  13. The convective engine paradigm for the supernova explosion mechanism and its consequences.

    NASA Astrophysics Data System (ADS)

    Herant, M.

    1995-05-01

    The convective engine paradigm for the explosion mechanism in core collapse supernovae is presented in a pedagogical manner. A candid evaluation of its strengths and weaknesses is attempted. The case where the convective mode corresponds to l=1, m=0 (one inflow, one outflow) is explored in more detail. The author also discusses the potential importance of such a convective pattern for neutron star kicks.

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

    PubMed

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

    2016-07-01

    Ceramic/polymer composite equipped with 3D interlocking skeleton (3D IL) is developed through a simple freeze-casting method, exhibiting exceptionally light weight, high strength, toughness, and shock resistance. Long-range crack energy dissipation enabled by 3D interlocking structure is considered as the primary reinforcing mechanism for such superior properties. The smart composite design strategy should hold a place in developing future structural engineering materials. PMID:27135462

  15. Supercharged two-cycle engines employing novel single element reciprocating shuttle inlet valve mechanisms and with a variable compression ratio

    NASA Technical Reports Server (NTRS)

    Wiesen, Bernard (Inventor)

    2008-01-01

    This invention relates to novel reciprocating shuttle inlet valves, effective with every type of two-cycle engine, from small high-speed single cylinder model engines, to large low-speed multiple cylinder engines, employing spark or compression ignition. Also permitting the elimination of out-of-phase piston arrangements to control scavenging and supercharging of opposed-piston engines. The reciprocating shuttle inlet valve (32) and its operating mechanism (34) is constructed as a single and simple uncomplicated member, in combination with the lost-motion abutments, (46) and (48), formed in a piston skirt, obviating the need for any complex mechanisms or auxiliary drives, unaffected by heat, friction, wear or inertial forces. The reciprocating shuttle inlet valve retains the simplicity and advantages of two-cycle engines, while permitting an increase in volumetric efficiency and performance, thereby increasing the range of usefulness of two-cycle engines into many areas that are now dominated by the four-cycle engine.

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

    PubMed Central

    Zakhem, Elie; Bitar, Khalil N.

    2015-01-01

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

  17. ‘Dopamine-first’ mechanism enables the rational engineering of the norcoclaurine synthase aldehyde activity profile

    PubMed Central

    Lichman, Benjamin R; Gershater, Markus C; Lamming, Eleanor D; Pesnot, Thomas; Sula, Altin; Keep, Nicholas H; Hailes, Helen C; Ward, John M

    2015-01-01

    Norcoclaurine synthase (NCS) (EC 4.2.1.78) catalyzes the Pictet–Spengler condensation of dopamine and an aldehyde, forming a substituted (S)-tetrahydroisoquinoline, a pharmaceutically important moiety. This unique activity has led to NCS being used for both in vitro biocatalysis and in vivo recombinant metabolism. Future engineering of NCS activity to enable the synthesis of diverse tetrahydroisoquinolines is dependent on an understanding of the NCS mechanism and kinetics. We assess two proposed mechanisms for NCS activity: (a) one based on the holo X-ray crystal structure and (b) the ‘dopamine-first’ mechanism based on computational docking. Thalictrum flavum NCS variant activities support the dopamine-first mechanism. Suppression of the non-enzymatic background reaction reveals novel kinetic parameters for NCS, showing it to act with low catalytic efficiency. This kinetic behaviour can account for the ineffectiveness of recombinant NCS in in vivo systems, and also suggests NCS may have an in planta role as a metabolic gatekeeper. The amino acid substitution L76A, situated in the proposed aldehyde binding site, results in the alteration of the enzyme's aldehyde activity profile. This both verifies the dopamine-first mechanism and demonstrates the potential for the rational engineering of NCS activity. PMID:25620686

  18. Mechanical characterization of tissue-engineered cartilage using microscopic magnetic resonance elastography.

    PubMed

    Yin, Ziying; Schmid, Thomas M; Yasar, Temel K; Liu, Yifei; Royston, Thomas J; Magin, Richard L

    2014-08-01

    Knowledge of mechanical properties of tissue-engineered cartilage is essential for the optimization of cartilage tissue engineering strategies. Microscopic magnetic resonance elastography (μMRE) is a recently developed MR-based technique that can nondestructively visualize shear wave motion. From the observed wave pattern in MR phase images the tissue mechanical properties (e.g., shear modulus or stiffness) can be extracted. For quantification of the dynamic shear properties of small and stiff tissue-engineered cartilage, μMRE needs to be performed at frequencies in the kilohertz range. However, at frequencies greater than 1 kHz shear waves are rapidly attenuated in soft tissues. In this study μMRE, with geometric focusing, was used to overcome the rapid wave attenuation at high frequencies, enabling the measurement of the shear modulus of tissue-engineered cartilage. This methodology was first tested at a frequency of 5 kHz using a model system composed of alginate beads embedded in agarose, and then applied to evaluate extracellular matrix development in a chondrocyte pellet over a 3-week culture period. The shear stiffness in the pellet was found to increase over time (from 6.4 to 16.4 kPa), and the increase was correlated with both the proteoglycan content and the collagen content of the chondrocyte pellets (R(2)=0.776 and 0.724, respectively). Our study demonstrates that μMRE when performed with geometric focusing can be used to calculate and map the shear properties within tissue-engineered cartilage during its development. PMID:24266395

  19. Multi-scale mechanical response of freeze-dried collagen scaffolds for tissue engineering applications.

    PubMed

    Offeddu, Giovanni S; Ashworth, Jennifer C; Cameron, Ruth E; Oyen, Michelle L

    2015-02-01

    Tissue engineering has grown in the past two decades as a promising solution to unresolved clinical problems such as osteoarthritis. The mechanical response of tissue engineering scaffolds is one of the factors determining their use in applications such as cartilage and bone repair. The relationship between the structural and intrinsic mechanical properties of the scaffolds was the object of this study, with the ultimate aim of understanding the stiffness of the substrate that adhered cells experience, and its link to the bulk mechanical properties. Freeze-dried type I collagen porous scaffolds made with varying slurry concentrations and pore sizes were tested in a viscoelastic framework by macroindentation. Membranes made up of stacks of pore walls were indented using colloidal probe atomic force microscopy. It was found that the bulk scaffold mechanical response varied with collagen concentration in the slurry consistent with previous studies on these materials. Hydration of the scaffolds resulted in a more compliant response, yet lesser viscoelastic relaxation. Indentation of the membranes suggested that the material making up the pore walls remains unchanged between conditions, so that the stiffness of the scaffolds at the scale of seeded cells is unchanged; rather, it is suggested that thicker pore walls or more of these result in the increased moduli for the greater slurry concentration conditions. PMID:25460922

  20. Mechanisms of fluid-flow-induced matrix production in bone tissue engineering.

    PubMed

    Morris, H L; Reed, C I; Haycock, J W; Reilly, G C

    2010-12-01

    Matrix production by tissue-engineered bone is enhanced when the growing tissue is subjected to mechanical forces and/or fluid flow in bioreactor culture. Cells deposit collagen and mineral, depending upon the mechanical loading that they receive. However, the molecular mechanisms of flow-induced signal transduction in bone are poorly understood. The hyaluronan (HA) glycocalyx has been proposed as a potential mediator of mechanical forces in bone. Using a parallel-plate flow chamber the effects of removal of HA on flow-induced collagen production and NF-kappaB activation in MLO-A5 osteoid osteocytes were investigated. Short periods of fluid flow significantly increased collagen production and induced translocation of the NF-kappaB subunit p65 to the cell's nuclei in 65 per cent of the cell population. Enzymatic removal of the HA coat and antibody blocking of CD44 (a transmembrane protein that binds to HA) eliminated the fluid-flow-induced increase in collagen production but had no effect on the translocation of p65. HA and CD44 appear to play roles in transducing the flow signals that modulate collagen production over long-term culture but not in the short-term flow-induced activation of NF-kappaB, implying that multiple signalling events are initiated from the commencement of flow. Understanding the mechanotransduction events that enable fluid flow to stimulate bone matrix production will allow the optimization of bioreactor design and flow profiles for bone tissue engineering. PMID:21287834

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

    PubMed

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

    2016-06-15

    Photoresponsive hydrogels were obtained by coordination of alginate-acrylamide hybrid gels (AlgAam) with ferric ions. The photochemistry of Fe(III)-alginate was used to tune the chemical composition, mechanical properties, and microstructure of the materials upon visible light irradiation. The photochemical treatment also induced changes in the swelling properties and transport mechanism in the gels due to the changes in material composition and microstructure. The AlgAam gels were biocompatible and could easily be dried and rehydrated with no change in mechanical properties. These gels showed promise as scaffolds for cartilage tissue engineering, where the photochemical treatment could be used to tune the properties of the material and ultimately change the growth and extracellular matrix production of chondrogenic cells. ATDC5 cells cultured on the hydrogels showed a greater than 2-fold increase in the production of sulfated glycosaminoglycans (sGAG) in the gels irradiated for 90 min compared to the dark controls. Our method provides a simple photochemical tool to postsynthetically control and adjust the chemical and mechanical environment in these gels, as well as the pore microstructure and transport properties. By changing these properties, we could easily access different levels of performance of these materials as substrates for tissue engineering. PMID:27223251

  2. Formation mechanism of chalcogenide nanocrystals confined inside genetically engineered virus-like particles

    NASA Astrophysics Data System (ADS)

    Zhou, Ziyou; Bedwell, Gregory J.; Li, Rui; Prevelige, Peter E.; Gupta, Arunava

    2014-01-01

    Engineered virus-like particles (VLP) are attractive for fabricating nanostructured materials for applications in diverse areas such as catalysis, drug delivery, biomedicine, composites, etc. Basic understanding of the interaction between the inorganic guest and biomolecular host is thus important for the controlled synthesis of inorganic nanoparticles inside VLP and rational assembly of ordered VLP-based hierarchical nanostructures. We have investigated in detail the formation mechanism and growth kinetics of semiconducting nanocrystals confined inside genetically engineered bacteriophage P22 VLP using semiconducting CdS as a prototypical example. The selective nucleation and growth of CdS at the engineered sites is found to be uniform during the early stage, followed by a more stochastic growth process. Furthermore, kinetic studies reveal that the presence of an engineered biotemplate helps in significantly retarding the reaction rate. These findings provide guidance for the controlled synthesis of a wide range of other inorganic materials confined inside VLP, and are of practical importance for the rational design of VLP-based hierarchical nanostuctures.

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

    PubMed

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

    2016-08-01

    Ultrasound techniques are increasingly being used to quantitatively characterize both native and engineered tissues. This review provides an overview and selected examples of the main techniques used in these applications. Grayscale imaging has been used to characterize extracellular matrix deposition, and quantitative ultrasound imaging based on the integrated backscatter coefficient has been applied to estimating cell concentrations and matrix morphology in tissue engineering. Spectral analysis has been employed to characterize the concentration and spatial distribution of mineral particles in a construct, as well as to monitor mineral deposition by cells over time. Ultrasound techniques have also been used to measure the mechanical properties of native and engineered tissues. Conventional ultrasound elasticity imaging and acoustic radiation force imaging have been applied to detect regions of altered stiffness within tissues. Sonorheometry and monitoring of steady-state excitation and recovery have been used to characterize viscoelastic properties of tissue using a single transducer to both deform and image the sample. Dual-mode ultrasound elastography uses separate ultrasound transducers to produce a more potent deformation force to microscale characterization of viscoelasticity of hydrogel constructs. These ultrasound-based techniques have high potential to impact the field of tissue engineering as they are further developed and their range of applications expands. PMID:26771992

  4. Research on compatibility mechanism of recycled poly(vinyl chloride) materials coming from flexible sheet with styrenic by-product, for application on hydro-sanitary sector

    NASA Astrophysics Data System (ADS)

    Garcia Sanoguera, David

    The treatment of waste is a topic that has grown in interest, due especially to the problem about location as a result of the fast growth of plastic waste during the last years. The PVC substitution by PET in packing sector has originated the disappearance of a residual source of excellent quality characterized by a good stiffness and used by other industries, like hydro-sanitary sector, main consumer of recycled PVC. The use of PVC coming from flexible sheets arises as alternative; however, in front of the residual coming from the packing industry, the PVC coming from credit cards presents a lower stiffness, since the origin product possesses high flexibility. For this reason, this material is not appropriate for hydro-sanitary sector which has a strict normative. The aim of this work is about the improvement of performance of recycled PVC coming from credit cards by means of mixing with different styrenic materials (SAN and ABS virgin and recycled), characterized by their high thermal stability. Previous degradation has been quantified in the recycled materials used by means of infrared analysis (FTIR), as well as miscibility has been determined in the different blends by means of Differential Scan Calorimetry (DSC). Also, the influence of styrenic materials on thermal stability of recycled PVC has been analyzed. Finally it has been carried out the study of mechanical properties of the different blends. On the other hand, different additives have been introduced in the blends, with the purpose of evaluating their influence in thermal and mechanical properties. It is necessary to take into account the low cost of recycled materials, as a consequence the additives cost will be a restrictive factor to consider for reaching some requirements, and also obtain an industrial application.

  5. Cell-Biomaterial Mechanical Interaction in the Framework of Tissue Engineering: Insights, Computational Modeling and Perspectives

    PubMed Central

    Sanz-Herrera, Jose A.; Reina-Romo, Esther

    2011-01-01

    Tissue engineering is an emerging field of research which combines the use of cell-seeded biomaterials both in vitro and/or in vivo with the aim of promoting new tissue formation or regeneration. In this context, how cells colonize and interact with the biomaterial is critical in order to get a functional tissue engineering product. Cell-biomaterial interaction is referred to here as the phenomenon involved in adherent cells attachment to the biomaterial surface, and their related cell functions such as growth, differentiation, migration or apoptosis. This process is inherently complex in nature involving many physico-chemical events which take place at different scales ranging from molecular to cell body (organelle) levels. Moreover, it has been demonstrated that the mechanical environment at the cell-biomaterial location may play an important role in the subsequent cell function, which remains to be elucidated. In this paper, the state-of-the-art research in the physics and mechanics of cell-biomaterial interaction is reviewed with an emphasis on focal adhesions. The paper is focused on the different models developed at different scales available to simulate certain features of cell-biomaterial interaction. A proper understanding of cell-biomaterial interaction, as well as the development of predictive models in this sense, may add some light in tissue engineering and regenerative medicine fields. PMID:22174660

  6. Design and fabrication of a cryostat for low temperature mechanical testing for the Mechanical and Materials Engineering group at CERN

    NASA Astrophysics Data System (ADS)

    Aviles Santillana, I.; Betemps, R.; Gerardin, A.; Guinchard, M.; Langeslag, S. A. E.; Sgobba, S.

    2015-12-01

    Mechanical testing of materials at low temperatures is one of the cornerstones of the Mechanical and Materials Engineering (MME) group at CERN. A long tradition of more than 20 years and a unique know - how of such tests has been developed with an 18 kN double-walled cryostat. Large campaigns of material qualification have been carried out and the mechanical behaviour of materials at 4 K has been vastly studied in sub - size samples for projects like LEP, LHC and its experiments. With the aim of assessing the mechanical properties of materials of higher strength and/or issued from heavy gauge products for which testing standardized specimens of larger cross section might be more adapted, a new 100 kN cryostat capable of hosting different shapes of normalized samples has been carefully designed and fabricated inhouse together with the associated tooling and measurement instrumentation. It has been conceived to be able to adapt to different test frames both dynamic and static, which will be of paramount importance for future studies of fracture mechanics at low temperatures. The cryostat features a double-walled vessel consisting of a central cylindrical section with a convex lower end and a flat top end closure. The transmission of the load is guaranteed by a 4 column system and its precise monitoring is assured by an internal load cell positioned next to the sample in the load train. This innovative approach will be discussed together with other nonconventional instrumentation solutions. A validation of the whole system has been carried out, where bending efforts on instrumented samples have been measured. Additionally, dedicated tooling has been fabricated for the device's optimization. The preliminary results obtained confirm an excellent performance of the system and enhance the analysis of materials under extreme conditions with state of the art instrumentation.

  7. Silicon subsystem mechanical engineering closeout report for the Solenoidal Detector Collaboration

    SciTech Connect

    Hanlon, J.; Christensen, R.W.; Hayman, G.; Jones, D.C.; Ross, R.; Wilds, W.; Yeamans, S.; Ziock, H.J.

    1995-02-01

    The authors group at Los Alamos National Laboratory was responsible for the mechanical engineering of the silicon tracking system of the Solenoidal Detector Collaboration (SDC) experiment of the Superconducting Super Collider (SSC) project. The responsibility included the overall design of the system from the mechanical point of view, development and integration of the cooling system, which was required to remove the heat generated by the front-end electronics, assembly of the system to extremely tight tolerances, and verification that the construction and operational stability and alignment tolerances would be met. A detailed description of the concepts they developed and the work they performed can be found in a report titled ``Silicon Subsystem Mechanical Engineering Work for the Solenoidal Detector Collaboration`` which they submitted to the SSC Laboratory. In addition to the mechanical engineering work, they also performed activation, background, and shielding studies for the SSC program. Much of the work they performed was potentially useful for other future high energy physics (HEP) projects. This report describes the closeout work that was performed for the Los Alamos SDC project. Four major tasks were identified for completion: (1) integration of the semi-automated assembly station being developed and construction of a precision part to demonstrate solutions to important general assembly problems (the station was designed to build precision silicon tracker subassemblies); (2) build a state-of-the-art TV holography (TVH) system to use for detector assembly stability tests; (3) design, build, and test a water based cooling system for a full silicon shell prototype; and (4) complete and document the activation, background, and shielding studies, which is covered in a separate report.

  8. Mechanobiology and Mechanotherapy of Adipose Tissue-Effect of Mechanical Force on Fat Tissue Engineering

    PubMed Central

    Yuan, Yi

    2015-01-01

    Summary: Our bodies are subjected to various mechanical forces, which in turn affect both the structure and function of our bodies. In particular, these mechanical forces play an important role in tissue growth and regeneration. Adipocytes and adipose-derived stem cells are both mechanosensitive and mechanoresponsive. The aim of this review is to summarize the relationship between mechanobiology and adipogenesis. PubMed was used to search for articles using the following keywords: mechanobiology, adipogenesis, adipose-derived stem cells, and cytoskeleton. In vitro and in vivo experiments have shown that adipogenesis is strongly promoted/inhibited by various internal and external mechanical forces, and that these effects are mediated by changes in the cytoskeleton of adipose-derived stem cells and/or various signaling pathways. Thus, adipose tissue engineering could be enhanced by the careful application of mechanical forces. It was shown recently that mature adipose tissue regenerates in an adipose tissue-engineering chamber. This observation has great potential for the reconstruction of soft tissue deficiencies, but the mechanisms behind it remain to be elucidated. On the basis of our understanding of mechanobiology, we hypothesize that the chamber removes mechanical force on the fat that normally impose high cytoskeletal tension. The reduction in tension in adipose stem cells triggers their differentiation into adipocytes. The improvement in our understanding of the relationship between mechanobiology and adipogenesis means that in the near future, we may be able to increase or decrease body fat, as needed in the clinic, by controlling the tension that is loaded onto fat. PMID:26894003

  9. Education of the Mechanical Engineering Literacy by the Collaboration Learning of the Different Grade

    NASA Astrophysics Data System (ADS)

    Nakashima, Kenji; Nakaura, Shigeki; Morita, Hidetoshi; Matsuyama, Fuminori; Nishiguchi, Hiroshi; Fukuda, Takayuki

    We trained business ability of the students through the senior instructing younger student system by fourth year students in the class of the practical skill. The theme of the practical skill is the resolution and the assembling of the gasoline engine, the automatic control of the radio control car with the PLC, the learning of dynamics using Mini-Yonku and the operation of the laser cutter. For the fourth students, we can expect an effect of their ability in the future work. For the first students, we can expect an effect for them to be interested in mechanical engineering. Concerning the effects of this project, all the fourth students and teachers discussed, and the effect of the project was evaluated by a poster session. As a result, we have found that more effects than we had expected has been gained.

  10. A Microfabricated Platform to Measure and Manipulate the Mechanics of Engineered Cardiac Microtissues

    PubMed Central

    Boudou, Thomas; Legant, Wesley R.; Mu, Anbin; Borochin, Michael A.; Thavandiran, Nimalan; Radisic, Milica; Zandstra, Peter W.; Epstein, Jonathan A.; Margulies, Kenneth B.

    2012-01-01

    Engineered myocardial tissues can be used to elucidate fundamental features of myocardial biology, develop organotypic in vitro model systems, and as engineered tissue constructs for replacing damaged heart tissue in vivo. However, a key limitation is an inability to test the wide range of parameters (cell source, mechanical, soluble and electrical stimuli) that might impact the engineered tissue in a high-throughput manner and in an environment that mimics native heart tissue. Here we used microelectromechanical systems technology to generate arrays of cardiac microtissues (CMTs) embedded within three-dimensional micropatterned matrices. Microcantilevers simultaneously constrain CMT contraction and report forces generated by the CMTs in real time. We demonstrate the ability to routinely produce ∼200 CMTs per million cardiac cells (<1 neonatal rat heart) whose spontaneous contraction frequency, duration, and forces can be tracked. Independently varying the mechanical stiffness of the cantilevers and collagen matrix revealed that both the dynamic force of cardiac contraction as well as the basal static tension within the CMT increased with boundary or matrix rigidity. Cell alignment is, however, reduced within a stiff collagen matrix; therefore, despite producing higher force, CMTs constructed from higher density collagen have a lower cross-sectional stress than those constructed from lower density collagen. We also study the effect of electrical stimulation on cell alignment and force generation within CMTs and we show that the combination of electrical stimulation and auxotonic load strongly improves both the structure and the function of the CMTs. Finally, we demonstrate the suitability of our technique for high-throughput monitoring of drug-induced changes in spontaneous frequency or contractility in CMTs as well as high-speed imaging of calcium dynamics using fluorescent dyes. Together, these results highlight the potential for this approach to quantitatively

  11. Hyaluronic Acid Enhances the Mechanical Properties of Tissue-Engineered Cartilage Constructs

    PubMed Central

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

    2014-01-01

    There is a need for materials that are well suited for cartilage tissue engineering. Hydrogels have emerged as promising biomaterials for cartilage repair, since, like cartilage, they have high water content, and they allow cells to be encapsulated within the material in a genuinely three-dimensional microenvironment. In this study, we investigated the mechanical properties of tissue-engineered cartilage constructs using in vitro culture models incorporating human chondrocytes from osteoarthritis patients. We evaluated hydrogels formed from mixtures of photocrosslinkable gelatin-methacrylamide (Gel-MA) and varying concentrations (0–2%) of hyaluronic acid methacrylate (HA-MA). Initially, only small differences in the stiffness of each hydrogel existed. After 4 weeks of culture, and to a greater extent 8 weeks of culture, HA-MA had striking and concentration dependent impact on the changes in mechanical properties. For example, the initial compressive moduli of cell-laden constructs with 0 and 1% HA-MA were 29 and 41 kPa, respectively. After 8 weeks of culture, the moduli of these constructs had increased to 66 and 147 kPa respectively, representing a net improvement of 69 kPa for gels with 1% HA-MA. Similarly the equilibrium modulus, dynamic modulus, failure strength and failure strain were all improved in constructs containing HA-MA. Differences in mechanical properties did not correlate with glycosaminoglycan content, which did not vary greatly between groups, yet there were clear differences in aggrecan intensity and distribution as assessed using immunostaining. Based on the functional development with time in culture using human chondrocytes, mixtures of Gel-MA and HA-MA are promising candidates for cartilage tissue-engineering applications. PMID:25438040

  12. Mapping of mechanical specimens by laser induced breakdown spectroscopy method: Application to an engine valve

    NASA Astrophysics Data System (ADS)

    Lopez-Quintas, I.; Mateo, M. P.; Piñon, V.; Yañez, A.; Nicolas, G.

    2012-08-01

    In this work, an engine valve composed of different alloys has been analyzed by laser- induced breakdown spectroscopy to prove the capability of this technique to characterize mechanical parts which are complex in terms of shape and composition. With the acquired spectral data, 3D chemical maps have been plotted using a computer application for four representative elements: Fe, Cr, Ni and Mn. In addition, information about the in-depth distribution of Cr and Fe in different parts of the valve is shown. Results prove the potential of this technique to be implemented as an evaluation tool for quality control.

  13. Biaxial Stretch Improves Elastic Fiber Maturation, Collagen Arrangement, and Mechanical Properties in Engineered Arteries.

    PubMed

    Huang, Angela H; Balestrini, Jenna L; Udelsman, Brooks V; Zhou, Kevin C; Zhao, Liping; Ferruzzi, Jacopo; Starcher, Barry C; Levene, Michael J; Humphrey, Jay D; Niklason, Laura E

    2016-06-01

    Tissue-engineered blood vessels (TEVs) are typically produced using the pulsatile, uniaxial circumferential stretch to mechanically condition and strengthen the arterial grafts. Despite improvements in the mechanical integrity of TEVs after uniaxial conditioning, these tissues fail to achieve critical properties of native arteries such as matrix content, collagen fiber orientation, and mechanical strength. As a result, uniaxially loaded TEVs can result in mechanical failure, thrombus, or stenosis on implantation. In planar tissue equivalents such as artificial skin, biaxial loading has been shown to improve matrix production and mechanical properties. To date however, multiaxial loading has not been examined as a means to improve mechanical and biochemical properties of TEVs during culture. Therefore, we developed a novel bioreactor that utilizes both circumferential and axial stretch that more closely simulates loading conditions in native arteries, and we examined the suture strength, matrix production, fiber orientation, and cell proliferation. After 3 months of biaxial loading, TEVs developed a formation of mature elastic fibers that consisted of elastin cores and microfibril sheaths. Furthermore, the distinctive features of collagen undulation and crimp in the biaxial TEVs were absent in both uniaxial and static TEVs. Relative to the uniaxially loaded TEVs, tissues that underwent biaxial loading remodeled and realigned collagen fibers toward a more physiologic, native-like organization. The biaxial TEVs also showed increased mechanical strength (suture retention load of 303 ± 14.53 g, with a wall thickness of 0.76 ± 0.028 mm) and increased compliance. The increase in compliance was due to combinatorial effects of mature elastic fibers, undulated collagen fibers, and collagen matrix orientation. In conclusion, biaxial stretching is a potential means to regenerate TEVs with improved matrix production, collagen organization, and mechanical

  14. 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…

  15. Effects of Structural Deformations of the Crank-Slider Mechanism on the Estimation of the Instantaneous Engine Friction Torque

    NASA Astrophysics Data System (ADS)

    CHALHOUB, N. G.; NEHME, H.; HENEIN, N. A.; BRYZIK, W.

    1999-07-01

    The focus on the current study is to assess the effects of structural deformations of the crankshaft/connecting-rod/piston mechanism on the computation of the instantaneous engine friction torque. This study is performed in a fully controlled environment in order to isolate the effects of structural deformations from those of measurement errors or noise interference. Therefore, a detailed model, accounting for the rigid and flexible motions of the crank-slider mechanism and including engine component friction formulations, is considered in this study. The model is used as a test bed to generate the engine friction torque,Tfa, and to predict the rigid and flexible motions of the system in response to the cylinder gas pressure. The torsional vibrations and the rigid body angular velocity of the crankshaft, as predicted by the detailed model of the crank-slider mechanism, are used along with the engine load torque and the cylinder gas pressure in the (P-ω) method to estimate the engine friction torque,Tfe. This method is well suited for the purpose of this study because its formulation is based on the rigid body model of the crank-slider mechanism. The digital simulation results demonstrate that the exclusion of the structural deformations of the crank-slider mechanism from the formulation of the (P-ω) method leads to an overestimation of the engine friction torque near the top-dead-center (TDC) position of the piston under firing conditions. Moreover, for the remainder of the engine cycle, the estimated friction torque exhibits large oscillations and takes on positive numerical values as if it is inducing energy into the system. Thus, the adverse effects of structural deformations of the crank-slider mechanism on the estimation of the engine friction torque greatly differ in their nature from one phase of the engine cycle to another.

  16. PGS:Gelatin nanofibrous scaffolds with tunable mechanical and structural properties for engineering cardiac tissues.

    PubMed

    Kharaziha, Mahshid; Nikkhah, Mehdi; Shin, Su-Ryon; Annabi, Nasim; Masoumi, Nafiseh; Gaharwar, Akhilesh K; Camci-Unal, Gulden; Khademhosseini, Ali

    2013-09-01

    A significant challenge in cardiac tissue engineering is the development of biomimetic grafts that can potentially promote myocardial repair and regeneration. A number of approaches have used engineered scaffolds to mimic the architecture of the native myocardium tissue and precisely regulate cardiac cell functions. However, previous attempts have not been able to simultaneously recapitulate chemical, mechanical, and structural properties of the myocardial extracellular matrix (ECM). In this study, we utilized an electrospinning approach to fabricate elastomeric biodegradable poly(glycerol sebacate) (PGS):gelatin nanofibrous scaffolds with a wide range of chemical composition, stiffness and anisotropy. Our findings demonstrated that through incorporation of PGS, it is possible to create nanofibrous scaffolds with well-defined anisotropy that mimic the left ventricular myocardium architecture. Furthermore, we studied attachment, proliferation, differentiation and alignment of neonatal rat cardiac fibroblast cells (CFs) as well as protein expression, alignment, and contractile function of cardiomyocyte (CMs) on PGS:gelatin scaffolds with variable amount of PGS. Notably, aligned nanofibrous scaffold, consisting of 33 wt. % PGS, induced optimal synchronous contractions of CMs while significantly enhanced cellular alignment. Overall, our study suggests that the aligned nanofibrous PGS:gelatin scaffold support cardiac cell organization, phenotype and contraction and could potentially be used to develop clinically relevant constructs for cardiac tissue engineering. PMID:23747008

  17. Mechanical evaluation of nHAp scaffold coated with poly-3-hydroxybutyrate for bone tissue engineering.

    PubMed

    Foroughi, Mohammad Reza; Karbasi, Saeed; Ebrahimi-Kahrizsangi, Reza

    2013-02-01

    Regeneration of bone, cartilage and osteochondral tissues by tissue engineering has attracted intense attention due to its potential advantages over the traditional replacement of tissues with synthetic implants. Nevertheless, there is still a dearth of ideal or suitable scaffolds based on porous biomaterials, and the present study was undertaken to develop and evaluate a useful porous composite scaffold system. In this study, nano hydroxyapatite (nHAp) powder made (about 35-45 nm) by heating at temperature of 900 degrees C and porous hydroxyapatite (40, 50 and 60 wt% solution) for making scaffold, by using Polyurethane sponge replication method. In order to increase the scaffolds mechanical properties, they coated with 2, 4 and 6 wt% Poly-3-hydroxybutyrate (P3HB) for 30 sec and 60 sec, respectively; after the scaffold coated by Polymer and survey results, this scaffold is nHAp/P3HB composite. Based on these results, this scaffold is an optimized one among three tested above mentioned composition and can be utilized in bone tissue engineering. In the result, the best of scaffold is with 50 wt% HAp and 6 wt% P3HB and porosity of present is between 80-90% with compressive strength and modulus 1.51 MPa and 22.73 MPa, respectively, that it can be application in bone tissue engineering. PMID:23646681

  18. PGS:Gelatin Nanofibrous Scaffolds with Tunable Mechanical and Structural Properties for Engineering Cardiac Tissues

    PubMed Central

    Kharaziha, Mahshid; Nikkhah, Mehdi; Shin, Su-Ryon; Annabi, Nasim; Masoumi, Nafiseh; Gaharwar, Akhilesh K.; Camci-Unal, Gulden; Khademhosseini, Ali

    2013-01-01

    A significant challenge in cardiac tissue engineering is the development of biomimetic grafts that can potentially promote myocardial repair and regeneration. A number of approaches have used engineered scaffolds to mimic the architecture of the native myocardium tissue and precisely regulate cardiac cell functions. However previous attempts have not been able to simultaneously recapitulate chemical, mechanical, and structural properties of the myocardial extracellular matrix (ECM). In this study, we utilized an electrospinning approach to fabricate elastomeric biodegradable poly(glycerol-sebacate) (PGS):gelatin scaffolds with a wide range of chemical composition, stiffness and anisotropy. Our findings demonstrated that through incorporation of PGS, it is possible to create nanofibrous scaffolds with well-defined anisotropy that mimics the left ventricular myocardium architecture. Furthermore, we studied attachment, proliferation, differentiation and alignment of neonatal rat cardiac fibroblast cells (CFs) as well as protein expression, alignment, and contractile function of cardiomyocyte (CMs) on PGS:gelatin scaffolds with variable amount of PGS. Notably, aligned nanofibrous scaffold, consisting of 33 wt. % PGS, induced optimal synchronous contractions of CMs while significantly enhanced cellular alignment. Overall, our study suggests that the aligned nanofibrous PGS:gelatin scaffold support cardiac cell organization, phenotype and contraction and could potentially be used to develop clinically relevant constructs for cardiac tissue engineering. PMID:23747008

  19. Grain Boundary Engineering the Mechanical Properties of Allvac 718Plus(Trademark) Superalloy

    NASA Technical Reports Server (NTRS)

    Gabb, Timothy P.; Telesman, Jack; Garg, Anita; Lin, Peter; Provenzano, virgil; Heard, Robert; Miller, Herbert M.

    2010-01-01

    Grain Boundary Engineering can enhance the population of structurally-ordered "low S" Coincidence Site Lattice (CSL) grain boundaries in the microstructure. In some alloys, these "special" grain boundaries have been reported to improve overall resistance to corrosion, oxidation, and creep resistance. Such improvements could be quite beneficial for superalloys, especially in conditions which encourage damage and cracking at grain boundaries. Therefore, the effects of GBE processing on high-temperature mechanical properties of the cast and wrought superalloy Allvac 718Plus (Allvac ATI) were screened. Bar sections were subjected to varied GBE processing, and then consistently heat treated, machined, and tested at 650 C. Creep, tensile stress relaxation, and dwell fatigue crack growth tests were performed. The influences of GBE processing on microstructure, mechanical properties, and associated failure modes are discussed.

  20. Quantitatively probing propensity for structural transitions in engineered virus nanoparticles by single-molecule mechanical analysis

    NASA Astrophysics Data System (ADS)

    Castellanos, Milagros; Carrillo, Pablo J. P.; Mateu, Mauricio G.

    2015-03-01

    Viruses are increasingly being studied from the perspective of fundamental physics at the nanoscale as biologically evolved nanodevices with many technological applications. In viral particles of the minute virus of mice (MVM), folded segments of the single-stranded DNA genome are bound to the capsid inner wall and act as molecular buttresses that increase locally the mechanical stiffness of the particle. We have explored whether a quantitative linkage exists in MVM particles between their DNA-mediated stiffening and impairment of a heat-induced, virus-inactivating structural change. A series of structurally modified virus particles with disrupted capsid-DNA interactions and/or distorted capsid cavities close to the DNA-binding sites were engineered and characterized, both in classic kinetics assays and by single-molecule mechanical analysis using atomic force microscopy. The rate constant of the virus inactivation reaction was found to decrease exponentially with the increase in elastic constant (stiffness) of the regions closer to DNA-binding sites. The application of transition state theory suggests that the height of the free energy barrier of the virus-inactivating structural transition increases linearly with local mechanical stiffness. From a virological perspective, the results indicate that infectious MVM particles may have acquired the biological advantage of increased survival under thermal stress by evolving architectural elements that rigidify the particle and impair non-productive structural changes. From a nanotechnological perspective, this study provides proof of principle that determination of mechanical stiffness and its manipulation by protein engineering may be applied for quantitatively probing and tuning the conformational dynamics of virus-based and other protein-based nanoassemblies.Viruses are increasingly being studied from the perspective of fundamental physics at the nanoscale as biologically evolved nanodevices with many technological

  1. Analysis of the working process and mechanical losses in a Stirling engine for a solar power unit

    SciTech Connect

    Makhkamov, K.K.; Ingham, D.B.

    1999-05-01

    In this paper a second level mathematical model for the computational simulation of the working process of a 1-kW Stirling engine has been used and the results obtained are presented. The internal circuit of the engine in the calculation scheme was divided into five chambers, namely, the expansion space, heater, regenerator, cooler and the compression space, and the governing system of ordinary differential equations for the energy and mass conservation were solved in each chamber by Euler`s method. In addition, mechanical losses in the construction of the engine have been determined and the computational results show that the mechanical losses for this particular design of the Stirling engine may be up to 50% of the indicated power of the engine.

  2. Possible Mechanisms for Turbofan Engine Ice Crystal Icing at High Altitude

    NASA Technical Reports Server (NTRS)

    Tsao, Jen-Ching; Struk, Peter M.; Oliver, Michael

    2014-01-01

    A thermodynamic model is presented to describe possible mechanisms of ice formation on unheated surfaces inside a turbofan engine compression system from fully glaciated ice crystal clouds often formed at high altitude near deep convective weather systems. It is shown from the analysis that generally there could be two distinct types of ice formation: (1) when the "surface freezing fraction" is in the range of 0 to 1, dominated by the freezing of water melt from fully or partially melted ice crystals, the ice structure is formed from accretion with strong adhesion to the surface, and (2) when the "surface melting fraction" is the range of 0 to 1, dominated by the further melting of ice crystals, the ice structure is formed from accumulation of un-melted ice crystals with relatively weak bonding to the surface. The model captures important qualitative trends of the fundamental ice-crystal icing phenomenon reported earlier1,2 from the research collaboration work by NASA and the National Research Council (NRC) of Canada. Further, preliminary analysis of test data from the 2013 full scale turbofan engine ice crystal icing test3 conducted in the NASA Glenn Propulsion Systems Laboratory (PSL) has also suggested that (1) both types of ice formation occurred during the test, and (2) the model has captured some important qualitative trend of turning on (or off) the ice crystal ice formation process in the tested engine low pressure compressor (LPC) targeted area under different icing conditions that ultimately would lead to (or suppress) an engine core roll back (RB) event.

  3. Possible Mechanisms for Turbofan Engine Ice Crystal Icing at High Altitude

    NASA Technical Reports Server (NTRS)

    Tsao, Jen-Ching; Struk, Peter M.; Oliver, Michael J.

    2016-01-01

    A thermodynamic model is presented to describe possible mechanisms of ice formation on unheated surfaces inside a turbofan engine compression system from fully glaciated ice crystal clouds often formed at high altitude near deep convective weather systems. It is shown from the analysis that generally there could be two distinct types of ice formation: (1) when the "surface freezing fraction" is in the range of 0 to 1, dominated by the freezing of water melt from fully or partially melted ice crystals, the ice structure is formed from accretion with strong adhesion to the surface, and (2) when the "surface melting fraction" is the range of 0 to 1, dominated by the further melting of ice crystals, the ice structure is formed from accumulation of un-melted ice crystals with relatively weak bonding to the surface. The model captures important qualitative trends of the fundamental ice-crystal icing phenomenon reported earlier (Refs. 1 and 2) from the research collaboration work by NASA and the National Research Council (NRC) of Canada. Further, preliminary analysis of test data from the 2013 full scale turbofan engine ice crystal icing test (Ref. 3) conducted in the NASA Glenn Propulsion Systems Laboratory (PSL) has also suggested that (1) both types of ice formation occurred during the test, and (2) the model has captured some important qualitative trend of turning on (or off) the ice crystal ice formation process in the tested engine low pressure compressor (LPC) targeted area under different icing conditions that ultimately would lead to (or suppress) an engine core roll back (RB) event.

  4. Influence of engineered interfaces on residual stresses and mechanical response in metal matrix composites

    NASA Technical Reports Server (NTRS)

    Arnold, Steven M.; Wilt, Thomas E.

    1992-01-01

    Because of the inherent coefficient of thermal expansion (CTE) mismatch between fiber and matrix within metal and intermetallic matrix composite systems, high residual stresses can develop under various thermal loading conditions. These conditions include cooling from processing temperature to room temperature as well as subsequent thermal cycling. As a result of these stresses, within certain composite systems, radial, circumferential, and/or longitudinal cracks have been observed to form at the fiber matrix interface region. A number of potential solutions for reducing this thermally induced residual stress field have been proposed recently. Examples of some potential solutions are high CTE fibers, fiber preheating, thermal anneal treatments, and an engineered interface. Here the focus is on designing an interface (by using a compensating/compliant layer concept) to reduce or eliminate the thermal residual stress field and, therefore, the initiation and propagation of cracks developed during thermal loading. Furthermore, the impact of the engineered interface on the composite's mechanical response when subjected to isothermal mechanical load histories is examined.

  5. Influence of engineered interfaces on residual stresses and mechanical response in metal matrix composites

    SciTech Connect

    Arnold, S.M.; Wilt, T.E.

    1992-03-01

    Because of the inherent coefficient of thermal expansion (CTE) mismatch between fiber and matrix within metal and intermetallic matrix composite systems, high residual stresses can develop under various thermal loading conditions. These conditions include cooling from processing temperature to room temperature as well as subsequent thermal cycling. As a result of these stresses, within certain composite systems, radial, circumferential, and/or longitudinal cracks have been observed to form at the fiber matrix interface region. A number of potential solutions for reducing this thermally induced residual stress field have been proposed recently. Examples of some potential solutions are high CTE fibers, fiber preheating, thermal anneal treatments, and an engineered interface. Here the focus is on designing an interface (by using a compensating/compliant layer concept) to reduce or eliminate the thermal residual stress field and, therefore, the initiation and propagation of cracks developed during thermal loading. Furthermore, the impact of the engineered interface on the composite's mechanical response when subjected to isothermal mechanical load histories is examined.

  6. Mechanical loading regulates human MSC differentiation in a multi-layer hydrogel for osteochondral tissue engineering.

    PubMed

    Steinmetz, Neven J; Aisenbrey, Elizabeth A; Westbrook, Kristofer K; Qi, H Jerry; Bryant, Stephanie J

    2015-07-01

    A bioinspired multi-layer hydrogel was developed for the encapsulation of human mesenchymal stem cells (hMSCs) as a platform for osteochondral tissue engineering. The spatial presentation of biochemical cues, via incorporation of extracellular matrix analogs, and mechanical cues, via both hydrogel crosslink density and externally applied mechanical loads, were characterized in each layer. A simple sequential photopolymerization method was employed to form stable poly(ethylene glycol)-based hydrogels with a soft cartilage-like layer of chondroitin sulfate and low RGD concentrations, a stiff bone-like layer with high RGD concentrations, and an intermediate interfacial layer. Under a compressive load, the variation in hydrogel stiffness within each layer produced high strains in the soft cartilage-like layer, low strains in the stiff bone-like layer, and moderate strains in the interfacial layer. When hMSC-laden hydrogels were cultured statically in osteochondral differentiation media, the local biochemical and matrix stiffness cues were not sufficient to spatially guide hMSC differentiation after 21 days. However dynamic mechanical stimulation led to differentially high expression of collagens with collagen II in the cartilage-like layer, collagen X in the interfacial layer and collagen I in the bone-like layer and mineral deposits localized to the bone layer. Overall, these findings point to external mechanical stimulation as a potent regulator of hMSC differentiation toward osteochondral cellular phenotypes. PMID:25900444

  7. Engineering tissue constructs to mimic native aortic and pulmonary valve leaflets' structures and mechanics

    NASA Astrophysics Data System (ADS)

    Masoumi, Nafiseh

    There are several disadvantages correlated with current heart valve replacement, including anticoagulation therapy for patients with mechanical valves and the low durability of bioprosthetic valves. The non-viable nature of such devices is a critical drawback especially for pediatric cases due to the inability of the graft to grow in vivo with the patients. A tissue engineered heart valve (TEHV) with remodeling and growth ability, is conceptually appealing to use in the surgical repair and could serve as a permanent replacements when operating for pediatric valvular lesions. It is critical that scaffolds for functional heart valve tissue engineering, be capable of mimicking the native leaflet's structure and mechanical properties at the time of implantation. Meanwhile, the scaffolds should be able to support cellular proliferation and native-like tissue formation as the TEHV remodels toward a scaffold-free state. Our overall hypothesis is that an "ideal" engineered construct, designed based on native leaflet's structure and mechanics, will complement a native heart valve leaflet in providing benchmarks for use in the design of clinically-applicable TEHV. This hypothesis was addressed through several experiments conducted in the present study. To establish a functional biomimetic TEHV, we developed scaffolds capable of matching the anisotropic stiffness of native leaflet while promoting native-like cell and collagen content and supporting the ECM generation. Scaffolds with various polymer contents (e.g., poly (glycerol sebacate) (PGS) and poly (epsilon-caprolactone) (PCL)) and structural designs (e.g., microfabricated and microfibrous scaffolds), were fabricated based on native leaflet's structure and mechanics. It was found that the tri-layered scaffold, designed with assembly of microfabricated PGS and microfibrous PGS/PCL was a functional leaflet capable of promoting tissue formation. Furthermore, to investigate the effect of cyclic stress and flexure

  8. Magnetically actuated tissue engineered scaffold: insights into mechanism of physical stimulation.

    PubMed

    Sapir-Lekhovitser, Yulia; Rotenberg, Menahem Y; Jopp, Juergen; Friedman, Gary; Polyak, Boris; Cohen, Smadar

    2016-02-14

    Providing the right stimulatory conditions resulting in efficient tissue promoting microenvironment in vitro and in vivo is one of the ultimate goals in tissue development for regenerative medicine. It has been shown that in addition to molecular signals (e.g. growth factors) physical cues are also required for generation of functional cell constructs. These cues are particularly relevant to engineering of biological tissues, within which mechanical stress activates mechano-sensitive receptors, initiating biochemical pathways which lead to the production of functionally mature tissue. Uniform magnetic fields coupled with magnetizable nanoparticles embedded within three dimensional (3D) scaffold structures remotely create transient physical forces that can be transferrable to cells present in close proximity to the nanoparticles. This study investigated the hypothesis that magnetically responsive alginate scaffold can undergo reversible shape deformation due to alignment of scaffold's walls in a uniform magnetic field. Using custom made Helmholtz coil setup adapted to an Atomic Force Microscope we monitored changes in matrix dimensions in situ as a function of applied magnetic field, concentration of magnetic particles within the scaffold wall structure and rigidity of the matrix. Our results show that magnetically responsive scaffolds exposed to an externally applied time-varying uniform magnetic field undergo a reversible shape deformation. This indicates on possibility of generating bending/stretching forces that may exert a mechanical effect on cells due to alternating pattern of scaffold wall alignment and relaxation. We suggest that the matrix structure deformation is produced by immobilized magnetic nanoparticles within the matrix walls resulting in a collective alignment of scaffold walls upon magnetization. The estimated mechanical force that can be imparted on cells grown on the scaffold wall at experimental conditions is in the order of 1 pN, which

  9. Magnetically actuated tissue engineered scaffold: insights into mechanism of physical stimulation

    NASA Astrophysics Data System (ADS)

    Sapir-Lekhovitser, Yulia; Rotenberg, Menahem Y.; Jopp, Juergen; Friedman, Gary; Polyak, Boris; Cohen, Smadar

    2016-02-01

    Providing the right stimulatory conditions resulting in efficient tissue promoting microenvironment in vitro and in vivo is one of the ultimate goals in tissue development for regenerative medicine. It has been shown that in addition to molecular signals (e.g. growth factors) physical cues are also required for generation of functional cell constructs. These cues are particularly relevant to engineering of biological tissues, within which mechanical stress activates mechano-sensitive receptors, initiating biochemical pathways which lead to the production of functionally mature tissue. Uniform magnetic fields coupled with magnetizable nanoparticles embedded within three dimensional (3D) scaffold structures remotely create transient physical forces that can be transferrable to cells present in close proximity to the nanoparticles. This study investigated the hypothesis that magnetically responsive alginate scaffold can undergo reversible shape deformation due to alignment of scaffold's walls in a uniform magnetic field. Using custom made Helmholtz coil setup adapted to an Atomic Force Microscope we monitored changes in matrix dimensions in situ as a function of applied magnetic field, concentration of magnetic particles within the scaffold wall structure and rigidity of the matrix. Our results show that magnetically responsive scaffolds exposed to an externally applied time-varying uniform magnetic field undergo a reversible shape deformation. This indicates on possibility of generating bending/stretching forces that may exert a mechanical effect on cells due to alternating pattern of scaffold wall alignment and relaxation. We suggest that the matrix structure deformation is produced by immobilized magnetic nanoparticles within the matrix walls resulting in a collective alignment of scaffold walls upon magnetization. The estimated mechanical force that can be imparted on cells grown on the scaffold wall at experimental conditions is in the order of 1 pN, which

  10. Example of Good Practice of a Learning Environment with a Classroom Response System in a Mechanical Engineering Bachelor Course

    ERIC Educational Resources Information Center

    Arteaga, Ines Lopez; Vinken, Esther

    2013-01-01

    Results of a successful pilot study are presented, in which quizzes are introduced in a second year bachelor course for mechanical engineering students. The pilot study course entailed the basic concepts of mechanical vibrations in complex, realistic structures. The quiz is held weekly using a SharePoint application. The purpose of the quizzes is…

  11. Infusion of Emerging Technologies and New Teaching Methods into the Mechanical Engineering Curriculum at the City College of New York

    ERIC Educational Resources Information Center

    Delale, Feridun; Liaw, Benjamin M.; Jiji, Latif M.; Voiculescu, Ioana; Yu, Honghui

    2011-01-01

    From October 2003 to April 2008 a systemic reform of the Mechanical Engineering program at The City College of New York was undertaken with the goal of incorporating emerging technologies (such as nanotechnology, biotechnology, Micro-Electro-Mechanical Systems (MEMS), intelligent systems) and new teaching methodologies (such as project based…

  12. Pressure for Fun: A Course Module for Increasing Chemical Engineering Students' Excitement and Interest in Mechanical Parts

    ERIC Educational Resources Information Center

    Scarbrough, Will J.; Case, Jennifer M.

    2006-01-01

    A new module in a first year mechanical drawing course was designed with the primary goal of exciting chemical engineering students about mechanical things. Other goals included increasing student ability and confidence to explain how things work. A variety of high intensity, hands-on, facilitated group activities using pumps and valves were…

  13. Replication of engine block cylinder bridge microstructure and mechanical properties with lab scale 319 Al alloy billet castings

    SciTech Connect

    Lombardi, A.; D'Elia, F.; Ravindran, C.; MacKay, R.

    2014-01-15

    In recent years, aluminum alloy gasoline engine blocks have in large part successfully replaced nodular cast iron engine blocks, resulting in improved vehicle fuel efficiency. However, because of the inadequate wear resistance properties of hypoeutectic Al–Si alloys, gray iron cylinder liners are required. These liners cause the development of large tensile residual stress along the cylinder bores and necessitate the maximization of mechanical properties in this region to prevent premature engine failure. The aim of this study was to replicate the engine cylinder bridge microstructure and mechanical properties following TSR treatment (which removes the sand binder to enable easy casting retrieval) using lab scale billet castings of the same alloy composition with varying cooling rates. Comparisons in microstructure between the engine block and the billet castings were carried out using optical and scanning electron microscopy, while mechanical properties were assessed using tensile testing. The results suggest that the microstructure at the top and middle of the engine block cylinder bridge was successfully replicated by the billet castings. However, the microstructure at the bottom of the cylinder was not completely replicated due to variations in secondary phase morphology and distribution. The successful replication of engine block microstructure will enable the future optimization of heat treatment parameters. - Highlights: • A method to replicate engine block microstructure was developed. • Billet castings will allow cost effective optimization of heat treatment process. • The replication of microstructure in the cylinder region was mostly successful. • Porosity was more clustered in the billet castings compared to the engine block. • Mechanical properties were lower in billet castings due to porosity and inclusions.

  14. Hybrid printing of mechanically and biologically improved constructs for cartilage tissue engineering applications.

    PubMed

    Xu, Tao; Binder, Kyle W; Albanna, Mohammad Z; Dice, Dennis; Zhao, Weixin; Yoo, James J; Atala, Anthony

    2013-03-01

    Bioprinting is an emerging technique used to fabricate viable, 3D tissue constructs through the precise deposition of cells and hydrogels in a layer-by-layer fashion. Despite the ability to mimic the native properties of tissue, printed 3D constructs that are composed of naturally-derived biomaterials still lack structural integrity and adequate mechanical properties for use in vivo, thus limiting their development for use in load-bearing tissue engineering applications, such as cartilage. Fabrication of viable constructs using a novel multi-head deposition system provides the ability to combine synthetic polymers, which have higher mechanical strength than natural materials, with the favorable environment for cell growth provided by traditional naturally-derived hydrogels. However, the complexity and high cost associated with constructing the required robotic system hamper the widespread application of this approach. Moreover, the scaffolds fabricated by these robotic systems often lack flexibility, which further restrict their applications. To address these limitations, advanced fabrication techniques are necessary to generate complex constructs with controlled architectures and adequate mechanical properties. In this study, we describe the construction of a hybrid inkjet printing/electrospinning system that can be used to fabricate viable tissues for cartilage tissue engineering applications. Electrospinning of polycaprolactone fibers was alternated with inkjet printing of rabbit elastic chondrocytes suspended in a fibrin-collagen hydrogel in order to fabricate a five-layer tissue construct of 1 mm thickness. The chondrocytes survived within the printed hybrid construct with more than 80% viability one week after printing. In addition, the cells proliferated and maintained their basic biological properties within the printed layered constructs. Furthermore, the fabricated constructs formed cartilage-like tissues both in vitro and in vivo as evidenced by the

  15. Composite electrospun gelatin fiber-alginate gel scaffolds for mechanically robust tissue engineered cornea.

    PubMed

    Tonsomboon, Khaow; Oyen, Michelle L

    2013-05-01

    A severe shortage of good quality donor cornea is now an international crisis in public health. Alternatives for donor tissue need to be urgently developed to meet the increasing demand for corneal transplantation. Hydrogels have been widely used as scaffolds for corneal tissue regeneration due to their large water content, similar to that of native tissue. However, these hydrogel scaffolds lack the fibrous structure that functions as a load-bearing component in the native tissue, resulting in poor mechanical performance. This work shows that mechanical properties of compliant hydrogels can be substantially enhanced with electrospun nanofiber reinforcement. Electrospun gelatin nanofibers were infiltrated with alginate hydrogels, yielding transparent fiber-reinforced hydrogels. Without prior crosslinking, electrospun gelatin nanofibers improved the tensile elastic modulus of the hydrogels from 78±19 kPa to 450±100 kPa. Stiffer hydrogels, with elastic modulus of 820±210 kPa, were obtained by crosslinking the gelatin fibers with carbodiimide hydrochloride in ethanol before the infiltration process, but at the expense of transparency. The developed fiber-reinforced hydrogels show great promise as mechanically robust scaffolds for corneal tissue engineering applications. PMID:23566770

  16. Prehistory effects on the VHCF behaviour of engineering metallic materials with different strengthening mechanisms

    NASA Astrophysics Data System (ADS)

    Zimmermann, M.; Stöcker, C.; Müller-Bollenhagen, C.; Christ, H.-J.

    2010-07-01

    Engineering materials often undergo a plastic deformation during manufacturing, hence the effect of a predeformation on the subsequent fatigue behaviour has to be considered. The effect of a prestrain on the microstructure is strongly influenced by the strengthening mechanism. Different mechanisms are relevant in the materials applied in this study: a solid-solution hardened and a precipitation-hardened nickel-base alloy and a martensite-forming metastable austenitic steel. Prehistory effects become very important, when fatigue failure at very high number of cycles (N > 107) is considered, since damage mechanisms occur different to those observed in the range of conventional fatigue limit. With the global strain amplitude being well below the static elastic limit, only inhomogeneously distributed local plastic deformation takes place in the very high cycle fatigue (VHCF) region. The dislocation motion during cyclic loading thus depends on the effective flow stress, which is defined by the global cyclic stress-strain relation and the local stress distribution as a consequence of the interaction between dislocations and precipitates, grain boundaries, martensite phases and micro-notches. As a consequence, no significant prehistory effect was observed for the VHCF behaviour of the solid-solution hardening alloy, while the precipitation-hardening alloy shows a perceptible prehistory dependence. In the case of the austenitic steel, strain-hardening and the volume fraction of the deformation-induced martensite dominate the fatigue behaviour.

  17. Mechanisms Relevant to the Enhanced Virulence of a Dihydroxynaphthalene-Melanin Metabolically Engineered Entomopathogen

    PubMed Central

    Tseng, Min-Nan; Chung, Chia-Ling; Tzean, Shean-Shong

    2014-01-01

    The entomopathogenic fungus Metarhizium anisopliae MA05-169 is a transformant strain that has been metabolically engineered to express dihydroxynaphthalene-melanin biosynthesis genes. In contrast to the wild type strain, the transformant displays a greater resistance to environmental stress and a higher virulence toward target insect host. However, the underlying mechanisms for these characteristics remain unclear; hence experiments were initiated to explore the possible mechanism(s) through physiological and molecular approaches. Although both transformant and wild type strains could infect and share the same insect host range, the former germinated faster and produced more appressoria than the latter, both in vivo and in vitro. The transformant showed a significantly shorter median lethal time (LT50) when infecting the diamondback moth (Plutella xylostella) and the striped flea beetle (Phyllotreta striolata), than the wild type. Additionally, the transformant was more tolerant to reactive oxygen species (ROS), produced 40-fold more orthosporin and notably overexpressed the transcripts of the pathogenicity-relevant hydrolytic enzymes (chitinase, protease, and phospholipase) genes in vivo. In contrast, appressorium turgor pressure and destruxin A content were slightly decreased compared to the wild type. The transformant's high anti-stress tolerance, its high virulence against five important insect pests (cowpea aphid Aphis craccivora, diamondback moth Pl. xylostella, striped flea beetle Ph. striolata, and silverleaf whitefly Bemisia argentifolii) and its capacity to colonize the root system are key properties for its potential bio-control field application. PMID:24662974

  18. Direct Mechanical Stimulation of Stem Cells: A Beating Electromechanically Active Scaffold for Cardiac Tissue Engineering.

    PubMed

    Gelmi, Amy; Cieslar-Pobuda, Artur; de Muinck, Ebo; Los, Marek; Rafat, Mehrdad; Jager, Edwin W H

    2016-06-01

    The combination of stem cell therapy with a supportive scaffold is a promising approach to improving cardiac tissue engineering. Stem cell therapy can be used to repair nonfunctioning heart tissue and achieve myocardial regeneration, and scaffold materials can be utilized in order to successfully deliver and support stem cells in vivo. Current research describes passive scaffold materials; here an electroactive scaffold that provides electrical, mechanical, and topographical cues to induced human pluripotent stem cells (iPS) is presented. The poly(lactic-co-glycolic acid) fiber scaffold coated with conductive polymer polypyrrole (PPy) is capable of delivering direct electrical and mechanical stimulation to the iPS. The electroactive scaffolds demonstrate no cytotoxic effects on the iPS as well as an increased expression of cardiac markers for both stimulated and unstimulated protocols. This study demonstrates the first application of PPy as a supportive electroactive material for iPS and the first development of a fiber scaffold capable of dynamic mechanical actuation. PMID:27126086

  19. Evading Quantum Mechanics: Engineering a Classical Subsystem within a Quantum Environment

    NASA Astrophysics Data System (ADS)

    Tsang, Mankei; Caves, Carlton M.

    2012-07-01

    Quantum mechanics is potentially advantageous for certain information-processing tasks, but its probabilistic nature and requirement of measurement backaction often limit the precision of conventional classical information-processing devices, such as sensors and atomic clocks. Here we show that, by engineering the dynamics of coupled quantum systems, it is possible to construct a subsystem that evades the measurement backaction of quantum mechanics, at all times of interest, and obeys any classical dynamics, linear or nonlinear, that we choose. We call such a system a quantum-mechanics-free subsystem (QMFS). All of the observables of a QMFS are quantum-nondemolition (QND) observables; moreover, they are dynamical QND observables, thus demolishing the widely held belief that QND observables are constants of motion. QMFSs point to a new strategy for designing classical information-processing devices in regimes where quantum noise is detrimental, unifying previous approaches that employ QND observables, backaction evasion, and quantum noise cancellation. Potential applications include gravitational-wave detection, optomechanical-force sensing, atomic magnetometry, and classical computing. Demonstrations of dynamical QMFSs include the generation of broadband squeezed light for use in interferometric gravitational-wave detection, experiments using entangled atomic-spin ensembles, and implementations of the quantum Toffoli gate.

  20. Degradation Mechanisms of an Advanced Jet Engine Service-Retired TBC Component

    NASA Astrophysics Data System (ADS)

    Wu, Rudder T.; Osawa, Makoto; Yokokawa, Tadaharu; Kawagishi, Kyoko; Harada, Hiroshi

    Current use of TBCs is subjected to premature spallation failure mainly due to the formation of thermally grown oxides (TGOs). Although extensive research has been carried out to gain better understanding of the thermo - mechanical and -chemical characteristics of TBCs, laboratory-scale studies and simulation tests are often carried out in conditions significantly differed from the complex and extreme environment typically of a modern gas-turbine engine, thus, failed to truly model service conditions. In particular, the difference in oxygen partial pressure and the effects of contaminants present in the engine compartment have often been neglected. In this respect, an investigation is carried out to study the in-service degradation of an EB-PVD TBC coated nozzle-guide vane. Several modes of degradation were observed due to three factors: 1) presence of residual stresses induced by the thermal-expansion mismatches, 2) evolution of bond coat microstructure and subsequent formation of oxide spinels, 3) deposition of CMAS on the surface of TBC.

  1. Electrical and mechanical characterisation of single wall carbon nanotubes based composites for tissue engineering applications.

    PubMed

    Whulanza, Yudan; Battini, Elena; Vannozzi, Lorenzo; Vomero, Maria; Ahluwalia, Arti; Vozzi, Giovanni

    2013-01-01

    This paper presents the realisation of conductive matrices for application to tissue engineering research. We used poly(L-lactide (PLLA)), poly(epsilon-caprolactone) (PCL), and poly(lactide-co-glycolide) (PLGA) as polymer matrix, because they are biocompatible and biodegradable. The conductive property was integrated to them by adding single wall carbon nanotubes (SWNTs) into the polymer matrix. Several SWNTs concentrations were introduced aiming to understand how they influence and modulate mechanical properties, impedance features and electric percolation threshold of polymer matrix. It was observed that a concentration of 0.3% was able to transform insulating matrix into conductive one. Furthermore, a conductive model of the SWNT/polymer was developed by applying power law of percolation threshold. PMID:23646716

  2. Understanding dental CAD/CAM for restorations--the digital workflow from a mechanical engineering viewpoint.

    PubMed

    Tapie, L; Lebon, N; Mawussi, B; Fron Chabouis, H; Duret, F; Attal, J-P

    2015-01-01

    As digital technology infiltrates every area of daily life, including the field of medicine, so it is increasingly being introduced into dental practice. Apart from chairside practice, computer-aided design/computer-aided manufacturing (CAD/CAM) solutions are available for creating inlays, crowns, fixed partial dentures (FPDs), implant abutments, and other dental prostheses. CAD/CAM dental solutions can be considered a chain of digital devices and software for the almost automatic design and creation of dental restorations. However, dentists who want to use the technology often do not have the time or knowledge to understand it. A basic knowledge of the CAD/CAM digital workflow for dental restorations can help dentists to grasp the technology and purchase a CAM/CAM system that meets the needs of their office. This article provides a computer-science and mechanical-engineering approach to the CAD/CAM digital workflow to help dentists understand the technology. PMID:25911827

  3. Use of general purpose mechanical computer assisted engineering software in orthopaedic surgical planning: advantages and limitations.

    PubMed

    Sutherland, C J; Bresina, S J; Gayou, D E

    1994-01-01

    Two surgical plans were developed for an appropriately complex reconstructive orthopaedic surgery case. One plan was developed with customary methods using two-dimensional (2D) radiographs. The second plan was developed with general purpose mechanical computer assisted engineering (MCAE) software using x-ray computed tomography (CT) data. The limitations of each method are identified. To create a surgical plan using three-dimensional (3D) medical datasets and MCAE software, five necessary steps were identified: (a) data reduction; (b) contour extraction; (c) 3D model creation; (d) extraction of mass properties; (e) model idealization. The principal limitation of general purpose MCAE software is the lack of pre-processing modules with which to address the unique requirements of medical image datasets. PMID:7850738

  4. Band gap engineering in polymers through chemical doping and applied mechanical strain.

    PubMed

    Lanzillo, Nicholas A; Breneman, Curt M

    2016-08-17

    We report simulations based on density functional theory and many-body perturbation theory exploring the band gaps of common crystalline polymers including polyethylene, polypropylene and polystyrene. Our reported band gaps of 8.6 eV for single-chain polyethylene and 9.1 eV for bulk crystalline polyethylene are in excellent agreement with experiment. The effects of chemical doping along the polymer backbone and side-groups are explored, and the use mechanical strain as a means to modify the band gaps of these polymers over a range of several eV while leaving the dielectric constant unchanged is discussed. This work highlights some of the opportunities available to engineer the electronic properties of polymers with wide-reaching implications for polymeric dielectric materials used for capacitive energy storage. PMID:27324304

  5. Band gap engineering in polymers through chemical doping and applied mechanical strain

    NASA Astrophysics Data System (ADS)

    Lanzillo, Nicholas A.; Breneman, Curt M.

    2016-08-01

    We report simulations based on density functional theory and many-body perturbation theory exploring the band gaps of common crystalline polymers including polyethylene, polypropylene and polystyrene. Our reported band gaps of 8.6 eV for single-chain polyethylene and 9.1 eV for bulk crystalline polyethylene are in excellent agreement with experiment. The effects of chemical doping along the polymer backbone and side-groups are explored, and the use mechanical strain as a means to modify the band gaps of these polymers over a range of several eV while leaving the dielectric constant unchanged is discussed. This work highlights some of the opportunities available to engineer the electronic properties of polymers with wide-reaching implications for polymeric dielectric materials used for capacitive energy storage.

  6. Engineering hyperactive variants of human deoxyribonuclease I by altering its functional mechanism.

    PubMed

    Pan, C Q; Lazarus, R A

    1997-06-01

    Human deoxyribonuclease I (DNase I), an enzyme used to treat cystic fibrosis patients, has been engineered to more effectively degrade double-stranded DNA to lower molecular weight fragments by altering its functional mechanism from the native single-stranded nicking pathway to a much more efficient one which results in increased double-stranded scission. By introducing positively charged amino acids at DNase I positions that can interact favorably with the proximal negatively charged phosphate groups of the DNA, we have created a hyperactive variant with approximately 35-fold higher DNA-degrading activity relative to wild type. This enhancement can be attributed to both a decrease in Km and an increase in Vmax. Furthermore, unlike wild-type DNase I, the hyperactive variants are no longer inhibited by physiological saline. Replacement of the same positions with negatively charged amino acids greatly reduced DNA cleavage activity, consistent with a repulsive effect with the neighboring DNA phosphates. In addition, these variants displayed similar activities toward a small synthetic substrate, p-nitrophenyl phenylphosphonate, suggesting that the difference in DNA cleavage activity is due to the interaction of the engineered charged residues with the DNA phosphate backbone rather than any change in catalytic machinery. Finally, experiments involving the repair of DNase I digested DNA with T4 DNA ligase and the Klenow fragment of DNA polymerase I suggest that single-stranded gaps are introduced by the hyperactive variants. Thus, the increased functional activity of the hyperactive variants may be explained in part by a shift toward a processive DNA nicking mechanism, which leads to a higher frequency of double-stranded breaks. PMID:9184142

  7. The use of physical and virtual manipulatives in an undergraduate mechanical engineering (Dynamics) course

    NASA Astrophysics Data System (ADS)

    Pan, Edward A.

    Science, technology, engineering, and mathematics (STEM) education is a national focus. Engineering education, as part of STEM education, needs to adapt to meet the needs of the nation in a rapidly changing world. Using computer-based visualization tools and corresponding 3D printed physical objects may help nontraditional students succeed in engineering classes. This dissertation investigated how adding physical or virtual learning objects (called manipulatives) to courses that require mental visualization of mechanical systems can aid student performance. Dynamics is one such course, and tends to be taught using lecture and textbooks with static diagrams of moving systems. Students often fail to solve the problems correctly and an inability to mentally visualize the system can contribute to student difficulties. This study found no differences between treatment groups on quantitative measures of spatial ability and conceptual knowledge. There were differences between treatments on measures of mechanical reasoning ability, in favor of the use of physical and virtual manipulatives over static diagrams alone. There were no major differences in student performance between the use of physical and virtual manipulatives. Students used the physical and virtual manipulatives to test their theories about how the machines worked, however their actual time handling the manipulatives was extremely limited relative to the amount of time they spent working on the problems. Students used the physical and virtual manipulatives as visual aids when communicating about the problem with their partners, and this behavior was also seen with Traditional group students who had to use the static diagrams and gesture instead. The explanations students gave for how the machines worked provided evidence of mental simulation; however, their causal chain analyses were often flawed, probably due to attempts to decrease cognitive load. Student opinions about the static diagrams and dynamic

  8. Sector-scanning echocardiography

    NASA Technical Reports Server (NTRS)

    Henry, W. L.; Griffith, J. M.

    1975-01-01

    The mechanical sector scanner is described in detail, and its clinical application is discussed. Cross sectional images of the heart are obtained in real time using this system. The sector scanner has three major components: (a) hand held scanner, (b) video display, and (c) video recorder. The system provides diagnostic information in a wide spectrum of cardiac diseases, and it quantitates the severity of mitral stenosis by measurement of the mitral valve orifice area in diagnosing infants, children and adults with cyanotic congenital heart disease.

  9. Engineering on the Straight and Narrow: The Mechanics of Nanofibrous Assemblies for Fiber-Reinforced Tissue Regeneration

    PubMed Central

    Baker, Brendon M.; Nerurkar, Nandan L.; Burdick, Jason A.; Li, Wan-Ju; Tuan, Rocky S.; Elliott, Dawn M.

    2009-01-01

    Tissue engineering of fibrous tissues of the musculoskeletal system represents a considerable challenge because of the complex architecture and mechanical properties of the component structures. Natural healing processes in these dense tissues are limited as a result of the mechanically challenging environment of the damaged tissue and the hypocellularity and avascular nature of the extracellular matrix. When healing does occur, the ordered structure of the native tissue is replaced with a disorganized fibrous scar with inferior mechanical properties, engendering sites that are prone to re-injury. To address the engineering of such tissues, we and others have adopted a structurally motivated approach based on organized nanofibrous assemblies. These scaffolds are composed of ultrafine polymeric fibers that can be fabricated in such a way to recreate the structural anisotropy typical of fiber-reinforced tissues. This straight-and-narrow topography not only provides tailored mechanical properties, but also serves as a 3D biomimetic micropattern for directed tissue formation. This review describes the underlying technology of nanofiber production and focuses specifically on the mechanical evaluation and theoretical modeling of these structures as it relates to native tissue structure and function. Applying the same mechanical framework for understanding native and engineered fiber-reinforced tissues provides a functional method for evaluating the utility and maturation of these unique engineered constructs. We further describe several case examples where these principles have been put to test, and discuss the remaining challenges and opportunities in forwarding this technology toward clinical implementation. PMID:19207040

  10. Increasing reliability of gas-air systems of piston and combined internal combustion engines by improving thermal and mechanic flow characteristics

    NASA Astrophysics Data System (ADS)

    Brodov, Yu. M.; Grigor'ev, N. I.; Zhilkin, B. P.; Plotnikov, L. V.; Shestakov, D. S.

    2015-12-01

    Results of experimental study of thermal and mechanical characteristics of gas exchange flow in piston and combined engines are presented. Ways for improving intake and exhaust processes to increase reliability of gas-air engine systems are proposed.

  11. Supersymmetric quantum mechanics: Engineered hierarchies of integrable potentials and related orthogonal polynomials

    SciTech Connect

    Balondo Iyela, Daddy; Govaerts, Jan; Hounkonnou, M. Norbert

    2013-09-15

    Within the context of supersymmetric quantum mechanics and its related hierarchies of integrable quantum Hamiltonians and potentials, a general programme is outlined and applied to its first two simplest illustrations. Going beyond the usual restriction of shape invariance for intertwined potentials, it is suggested to require a similar relation for Hamiltonians in the hierarchy separated by an arbitrary number of levels, N. By requiring further that these two Hamiltonians be in fact identical up to an overall shift in energy, a periodic structure is installed in the hierarchy which should allow for its resolution. Specific classes of orthogonal polynomials characteristic of such periodic hierarchies are thereby generated, while the methods of supersymmetric quantum mechanics then lead to generalised Rodrigues formulae and recursion relations for such polynomials. The approach also offers the practical prospect of quantum modelling through the engineering of quantum potentials from experimental energy spectra. In this paper, these ideas are presented and solved explicitly for the cases N= 1 and N= 2. The latter case is related to the generalised Laguerre polynomials, for which indeed new results are thereby obtained. In the context of dressing chains and deformed polynomial Heisenberg algebras, some partial results for N⩾ 3 also exist in the literature, which should be relevant to a complete study of the N⩾ 3 general periodic hierarchies.

  12. Continuum theory of fibrous tissue damage mechanics using bond kinetics: application to cartilage tissue engineering.

    PubMed

    Nims, Robert J; Durney, Krista M; Cigan, Alexander D; Dusséaux, Antoine; Hung, Clark T; Ateshian, Gerard A

    2016-02-01

    This study presents a damage mechanics framework that employs observable state variables to describe damage in isotropic or anisotropic fibrous tissues. In this mixture theory framework, damage is tracked by the mass fraction of bonds that have broken. Anisotropic damage is subsumed in the assumption that multiple bond species may coexist in a material, each having its own damage behaviour. This approach recovers the classical damage mechanics formulation for isotropic materials, but does not appeal to a tensorial damage measure for anisotropic materials. In contrast with the classical approach, the use of observable state variables for damage allows direct comparison of model predictions to experimental damage measures, such as biochemical assays or Raman spectroscopy. Investigations of damage in discrete fibre distributions demonstrate that the resilience to damage increases with the number of fibre bundles; idealizing fibrous tissues using continuous fibre distribution models precludes the modelling of damage. This damage framework was used to test and validate the hypothesis that growth of cartilage constructs can lead to damage of the synthesized collagen matrix due to excessive swelling caused by synthesized glycosaminoglycans. Therefore, alternative strategies must be implemented in tissue engineering studies to prevent collagen damage during the growth process. PMID:26855751

  13. Improvements in Mechanical Properties of 319 Al Alloy Engine Blocks Through Cost-Effective Solution Heat Treatment

    NASA Astrophysics Data System (ADS)

    Lombardi, A.; Ravindran, C.; MacKay, R.

    2014-08-01

    The use of Al engine blocks has increased significantly to improve vehicle fuel efficiency. However, the gray cast iron cylinder liners cause the development of large tensile residual stress along the cylinder bores which necessitates the optimization of mechanical properties in this region to prevent premature engine failure. This study compared the microstructure of T4-treated Al billet castings of varying cooling rate to that of the cylinder region of T4-treated (current production schedule) Al engine blocks. The aim of this study was to develop a cost-effective small scale heat treatment optimization method for engine block production. Comparisons in microstructure between the engine block and the billet castings were carried out using optical and scanning electron microscopy. The results suggest that the microstructure and hardness at the top, middle, and bottom of the cylinder were similar to those of each representative billet casting, indicating that heat treatment resulted in successful replication of the engine block locations. In addition, tensile testing revealed that the YS and UTS increased slightly following T4 treatment for all billet castings, which was also observed at the middle of the engine block cylinder bridge. As such, this method can be an effective forerunner for future heat treatment optimization in Al engine block production.

  14. Relationship between micro-porosity, water permeability and mechanical behavior in scaffolds for cartilage engineering.

    PubMed

    Vikingsson, L; Claessens, B; Gómez-Tejedor, J A; Gallego Ferrer, G; Gómez Ribelles, J L

    2015-08-01

    In tissue engineering the design and optimization of biodegradable polymeric scaffolds with a 3D-structure is an important field. The porous scaffold provide the cells with an adequate biomechanical environment that allows mechanotransduction signals for cell differentiation and the scaffolds also protect the cells from initial compressive loading. The scaffold have interconnected macro-pores that host the cells and newly formed tissue, while the pore walls should be micro-porous to transport nutrients and waste products. Polycaprolactone (PCL) scaffolds with a double micro- and macro-pore architecture have been proposed for cartilage regeneration. This work explores the influence of the micro-porosity of the pore walls on water permeability and scaffold compliance. A Poly(Vinyl Alcohol) with tailored mechanical properties has been used to simulate the growing cartilage tissue inside the scaffold pores. Unconfined and confined compression tests were performed to characterize both the water permeability and the mechanical response of scaffolds with varying size of micro-porosity while volume fraction of the macro-pores remains constant. The stress relaxation tests show that the stress response of the scaffold/hydrogel construct is a synergic effect determined by the performance of the both components. This is interesting since it suggests that the in vivo outcome of the scaffold is not only dependent upon the material architecture but also the growing tissue inside the scaffold׳s pores. On the other hand, confined compression results show that compliance of the scaffold is mainly controlled by the micro-porosity of the scaffold and less by hydrogel density in the scaffold pores. These conclusions bring together valuable information for customizing the optimal scaffold and to predict the in vivo mechanical behavior. PMID:25913609

  15. Mechanical properties and in vitro behavior of nanofiber-hydrogel composites for tissue engineering applications

    NASA Astrophysics Data System (ADS)

    Kai, Dan; Prabhakaran, Molamma P.; Stahl, Benjamin; Eblenkamp, Markus; Wintermantel, Erich; Ramakrishna, Seeram

    2012-03-01

    Hydrogel-based biomaterial systems have great potential for tissue reconstruction by serving as temporary scaffolds and cell delivery vehicles for tissue engineering (TE). Hydrogels have poor mechanical properties and their rapid degradation limits the development and application of hydrogels in TE. In this study, nanofiber reinforced composite hydrogels were fabricated by incorporating electrospun poly(ɛ-caprolactone) (PCL)/gelatin ‘blend’ or ‘coaxial’ nanofibers into gelatin hydrogels. The morphological, mechanical, swelling and biodegradation properties of the nanocomposite hydrogels were evaluated and the results indicated that the moduli and compressive strengths of the nanofiber reinforced hydrogels were remarkably higher than those of pure gelatin hydrogels. By increasing the amount of incorporated nanofibers into the hydrogel, the Young’s modulus of the composite hydrogels increased from 3.29 ± 1.02 kPa to 20.30 ± 1.79 kPa, while the strain at break decreased from 66.0 ± 1.1% to 52.0 ± 3.0%. Compared to composite hydrogels with coaxial nanofibers, those with blend nanofibers showed higher compressive strength and strain at break, but with lower modulus and energy dissipation properties. Biocompatibility evaluations of the nanofiber reinforced hydrogels were carried out using bone marrow mesenchymal stem cells (BM-MSCs) by cell proliferation assay and immunostaining analysis. The nanocomposite hydrogel with 25 mg ml-1 PCL/gelatin ‘blend’ nanofibers (PGB25) was found to enhance cell proliferation, indicating that the ‘nanocomposite hydrogels’ might provide the necessary mechanical support and could be promising cell delivery systems for tissue regeneration.

  16. Mechanical properties and in vitro behavior of nanofiber-hydrogel composites for tissue engineering applications.

    PubMed

    Kai, Dan; Prabhakaran, Molamma P; Stahl, Benjamin; Eblenkamp, Markus; Wintermantel, Erich; Ramakrishna, Seeram

    2012-03-01

    Hydrogel-based biomaterial systems have great potential for tissue reconstruction by serving as temporary scaffolds and cell delivery vehicles for tissue engineering (TE). Hydrogels have poor mechanical properties and their rapid degradation limits the development and application of hydrogels in TE. In this study, nanofiber reinforced composite hydrogels were fabricated by incorporating electrospun poly(ε-caprolactone) (PCL)/gelatin 'blend' or 'coaxial' nanofibers into gelatin hydrogels. The morphological, mechanical, swelling and biodegradation properties of the nanocomposite hydrogels were evaluated and the results indicated that the moduli and compressive strengths of the nanofiber reinforced hydrogels were remarkably higher than those of pure gelatin hydrogels. By increasing the amount of incorporated nanofibers into the hydrogel, the Young's modulus of the composite hydrogels increased from 3.29 ± 1.02 kPa to 20.30 ± 1.79 kPa, while the strain at break decreased from 66.0 ± 1.1% to 52.0 ± 3.0%. Compared to composite hydrogels with coaxial nanofibers, those with blend nanofibers showed higher compressive strength and strain at break, but with lower modulus and energy dissipation properties. Biocompatibility evaluations of the nanofiber reinforced hydrogels were carried out using bone marrow mesenchymal stem cells (BM-MSCs) by cell proliferation assay and immunostaining analysis. The nanocomposite hydrogel with 25 mg ml(-1) PCL/gelatin 'blend' nanofibers (PGB25) was found to enhance cell proliferation, indicating that the 'nanocomposite hydrogels' might provide the necessary mechanical support and could be promising cell delivery systems for tissue regeneration. PMID:22322583

  17. Dynamic mechanical properties of the tissue-engineered matrix associated with individual chondrocytes.

    PubMed

    Lee, Bobae; Han, Lin; Frank, Eliot H; Chubinskaya, Susan; Ortiz, Christine; Grodzinsky, Alan J

    2010-02-10

    The success of cell-based tissue engineering approaches in restoring biological function will be facilitated by a comprehensive fundamental knowledge of the temporal evolution of the structure and properties of the newly synthesized matrix. Here, we quantify the dynamic oscillatory mechanical behavior of the engineered matrix associated with individual chondrocytes cultured in vitro for up to 28 days in alginate scaffolds. The magnitude of the complex modulus (|E*|) and phase shift (delta) were measured in culture medium using Atomic Force Microscopy (AFM)-based nanoindentation in response to an imposed oscillatory deformation (amplitude approximately 5nm) as a function of frequency (f=1-316Hz), probe tip geometry (2.5microm radius sphere and 50nm radius square pyramid), and in the absence and presence of growth factors (GF, insulin growth factor-1, IGF-1, and osteogenic protein-1, OP-1). |E*| for all conditions increased nonlinearly with frequency dependence approximately f(1/2) and ranged between approximately 1 and 25kPa. This result, along with theoretical calculations of the characteristic poroelastic relaxation frequency, f(p), (approximately 50-90Hz) suggested that this time-dependent behavior was governed primarily by fluid flow-dependent poroelasticity, rather than flow-independent viscoelastic processes associated with the solid matrix. |E*(f)| increased, (f) decreased, and the hydraulic permeability, k, decreased with time in culture and with growth factor treatment. This trend of a more elastic-like response was thought to be associated with increased macromolecular biosynthesis, density, and a more mature matrix structure/organization. PMID:19889416

  18. Dynamic mechanical properties of the tissue-engineered matrix associated with individual chondrocytes

    PubMed Central

    Lee, BoBae; Han, Lin; Frank, Eliot H.; Chubinskaya, Susan; Ortiz, Christine; Grodzinsky, Alan J.

    2009-01-01

    The success of cell-based tissue engineering approaches in restoring biological function will be facilitated by a comprehensive fundamental knowledge base of the temporal evolution of the structure and properties of the newly synthesized matrix. Here, we quantify the dynamic oscillatory mechanical behavior of the engineered matrix associated with individual chondrocytes cultured in vitro for up to 28 days in alginate scaffolds. The magnitude of the complex modulus (|E*|) and phase shift (δ) were measured in culture medium using Atomic Force Microscopy (AFM)-based nanoindentation in response to an imposed oscillatory deformation (amplitude ~ 5nm) as a function of frequency (f =1-316 Hz), probe tip geometry (2.5 μmm radius sphere and 50 nm radius square pyramid), and in the absence and presence growth factors (GF, insulin growth factor-1, IGF-1, and osteogenic protein-1, OP-1). |E*| for all conditions increased nonlinearly with frequency dependence approximately f1/2 and ranged between ~1-25 kPa. This result, along with theoretical calculations of the characteristic poroelastic relaxation frequency, fp, (~50-90 Hz) suggested that this time-dependent behavior was governed primarily by fluid flow-dependent poroelasticity, rather than flow-independent viscoelastic processes associated with the solid matrix. |E*(f)| increased, δ(f) decreased, and the hydraulic permeability, k, decreased with time in culture and with growth factor treatment. This trend of a more elastic-like response was thought to be associated with increased macromolecular biosynthesis, density, and a more mature matrix structure/organization. PMID:19889416

  19. Systematic analysis of intracellular mechanisms of propanol production in the engineered Thermobifida fusca B6 strain.

    PubMed

    Deng, Yu; Fisher, Adam B; Fong, Stephen S

    2015-10-01

    Thermobifida fusca is a moderately thermophilic actinobacterium naturally capable of utilizing lignocellulosic biomass. The B6 strain of T. fusca was previously engineered to produce 1-propanol directly on lignocellulosic biomass by expressing a bifunctional butyraldehyde/alcohol dehydrogenase (adhE2). To characterize the intracellular mechanisms related to the accumulation of 1-propanol, the engineered B6 and wild-type (WT) strains were systematically compared by analysis of the transcriptome and intracellular metabolome during exponential growth on glucose, cellobiose, and Avicel. Of the 18 known cellulases in T. fusca, 10 cellulase genes were transcriptionally expressed on all three substrates along with three hemicellulases. Transcriptomic analysis of cellodextrin and cellulose transport revealed that Tfu_0936 (multiple sugar transport system permease) was the key enzyme regulating the uptake of sugars in T. fusca. For both WT and B6 strains, it was found that growth in oxygen-limited conditions resulted in a blocked tricarboxylic acid (TCA) cycle caused by repressed expression of Tfu_1925 (aconitate hydratase). Further, the transcriptome suggested a pathway for synthesizing succinyl-CoA: oxaloacetate to malate (by malate dehydrogenase), malate to fumarate (by fumarate hydratase), and fumarate to succinate (by succinate dehydrogenase/fumarate reductase) which was ultimately converted to succinyl-CoA by succinyl-CoA synthetase. Both the transcriptome and the intracellular metabolome confirmed that 1-propanol was produced through succinyl-CoA, L-methylmalonyl-CoA, D-methylmalonyl-CoA, and propionyl-CoA in the B6 strain. PMID:26227414

  20. Cirrus cloud seeding: a climate engineering mechanism with reduced side effects?

    PubMed

    Storelvmo, T; Boos, W R; Herger, N

    2014-12-28

    Climate engineering, the intentional alteration of Earth's climate, is a multifaceted and controversial topic. Numerous climate engineering mechanisms (CEMs) have been proposed, and the efficacies and potential undesired consequences of some of them have been studied in the safe environments of numerical models. Here, we present a global modelling study of a so far understudied CEM, namely the seeding of cirrus clouds to reduce their lifetimes in the upper troposphere, and hence their greenhouse effect. Different from most CEMs, the intention of cirrus seeding is not to reduce the amount of solar radiation reaching Earth's surface. This particular CEM rather targets the greenhouse effect, by reducing the trapping of infrared radiation by high clouds. This avoids some of the caveats that have been identified for solar radiation management, for example, the delayed recovery of stratospheric ozone or drastic changes to Earth's hydrological cycle. We find that seeding of mid- and high-latitude cirrus clouds has the potential to cool the planet by about 1.4 K, and that this cooling is accompanied by only a modest reduction in rainfall. Intriguingly, seeding of the 15% of the globe with the highest solar noon zenith angles at any given time yields the same global mean cooling as a seeding strategy that involves 45% of the globe. In either case, the cooling is strongest at high latitudes, and could therefore serve to prevent Arctic sea ice loss. With the caveat that there are still significant uncertainties associated with ice nucleation in cirrus clouds and its representation in climate models, cirrus seeding appears to represent a powerful CEM with reduced side effects. PMID:25404685

  1. Observation of TEC perturbation associated with medium-scale traveling ionospheric disturbance and possible seeding mechanism of atmospheric gravity wave at a Brazilian sector

    NASA Astrophysics Data System (ADS)

    Jonah, O. F.; Kherani, E. A.; De Paula, E. R.

    2016-03-01

    In the present study, we document daytime total electron content (TEC) disturbances associated with medium-scale traveling ionospheric disturbances (MSTIDs), on few chosen geomagnetically quiet days over Southern Hemisphere of Brazilian longitude sector. These disturbances are derived from TEC data obtained using Global Navigation Satellite System (GNSS) receiver networks. From the keograms and cross-correlation maps, the TEC disturbances are identified as the MSTIDs that are propagating equatorward-eastward, having most of their average wavelengths longer in latitude than in longitude direction. These are the important outcomes of the present study which suggest that the daytime MSTIDs over Southern Hemisphere are similar to their counterparts in the Northern Hemisphere. Another important outcome is that the occurrence characteristics of these MSTIDs and that of atmospheric gravity wave (AGW) activities in the thermosphere are found to be similar on day-to-day basis. This suggests a possible connection between them, confirming the widely accepted AGW forcing mechanism for the generation of these daytime MSTIDs. The source of this AGW is investigated using the Geostationary Operational Environmental Satellite system (GOES) and Constellation Observing System for Meteorology, Ionosphere, and Climate satellite data. Finally, we provided evidences that AGWs are generated by convection activities from the tropospheric region.

  2. Teaching design in the first years of a traditional mechanical engineering degree: methods, issues and future perspectives

    NASA Astrophysics Data System (ADS)

    Silva, Arlindo; Fontul, Mihail; Henriques, Elsa

    2015-01-01

    Engineering design is known as an answer to an ill-defined problem. As any answer to an ill-defined problem, it can never be completely right or absolutely wrong. The methods that universities use to teach engineering design, as a consequence of this, suffer from the same fate. However, the accumulated experience with the 'chalk and talk' teaching tradition has led to a reality in which the employers of fresh graduates are not happy with the engineers they are getting. Part of their complaints are related with the inability of recently graduate engineers to work in problems where the boundaries are not well defined, are interdisciplinary, require the use of effective communication and integrate non-technical issues. These skills are mostly absent from traditional engineering curricula. This paper demonstrates the implementation of engineering design perspectives enhancing some of the aforementioned skills in a traditional mechanical engineering curriculum. It emphasises in particular a design project that is tackled in a sequence of conventional courses with a focus that depends on the course objectives and disciplinary domain. This transdisciplinary design project conveys the idea (and effectively implements it concurrently) that design is multidisciplinary.

  3. Mechanical Engineering at KSC: 'How I spend My Hours from 9 to 5 and Draw a Paycheck'

    NASA Technical Reports Server (NTRS)

    Randazzo, John; Steinrock. Todd (Technical Monitor)

    2003-01-01

    This viewgraph presentation provides an overview of a senior mechanical engineer's role in designing and testing sensors to fly aboard the shuttle Discovery during STS-95 and STS-98. Topics covered include: software development tools, computation fluid dynamics, structural analysis, housing design, and systems integration.

  4. Physics of Mechanical, Gaseous, and Fluid Systems. A Study Guide of the Science and Engineering Technician Curriculum.

    ERIC Educational Resources Information Center

    Dixon, Peggy; And Others

    This study guide is part of a program of studies entitled Science and Engineering Technician (SET) Curriculum. The SET Curriculum integrates elements from the disciplines of chemistry, physics, mathematics, mechanical technology, and electronic technology. The objective of this curriculum development project is to train technicians in the use of…

  5. 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…

  6. Development and Validation of Mechanical Engineering Trade Skills Assessment Instrument for Sustainable Job Security in Yobe State

    ERIC Educational Resources Information Center

    Adamu, Gishua Garba; Dawha, Josphine Musa; Kamar, Tiamiyu Salihu

    2015-01-01

    Mechanical Engineering Trade Skills Assessment Instrument (METSAI) is aimed at determining the extent to which students have acquired practical skills before graduation that will enable them get employment for sustainable job security in Yobe state. The study employed instrumentation research design. The populations of the study were 23 mechanical…

  7. Wear and wear mechanism simulation of heavy-duty engine intake valve and seat inserts

    SciTech Connect

    Wang, Y.S.; Narasimhan, S.; Larson, J.M.; Schaefer, S.K.

    1998-02-01

    A silicon-chromium alloy frequently used for heavy-duty diesel engine intake valves was tested against eight different insert materials with a valve seat wear simulator. Wear resistance of these combinations was ranked. For each test, the valve seat temperature was controlled at approximately 510 C, the number of cycles was 864,000 (or 24 h), and the test load was 17,640 N. The combination of the silicon-chromium valve against a cast iron insert produced in the least valve seat wear, whereas a cobalt-base alloy insert produced the highest valve seat wear. In the overall valve seat recession ranking, however, the combination of the silicon-chromium valve and an iron-base chromium-nickel alloy insert had the least total seat recession, whereas the silicon-chromium valve against cobalt-base alloy, cast iron, and nickel-base alloy inserts had significant seat recession. Hardness and microstructure compatibility of valve and insert materials are believed to be significant factors in reducing valve and insert wear. The test results indicate that the mechanisms of valve seat and insert wear are a complex combination of adhesion and plastic deformation. Adhesion was confirmed by material transfer, while plastic deformation was verified by shear strain (or radial flow) and abrasion. The oxide films formed during testing also played a significant role. The prevented direct metal-to-metal contact and reduced the coefficient of friction on seat surfaces, thereby reducing adhesive and deformation-controlled wear.

  8. Combined decellularisation and dehydration improves the mechanical properties of tissue-engineered sinews

    PubMed Central

    Lebled, Claire; Grover, Liam M

    2014-01-01

    Novel sources of replacement sinews are needed to repair damaged tissue after injury. The current methods of repair ultilise autografts, allografts or xenografts, although each method has distinct disadvantages that limit their success. Decellularisation of harvested tissues has been previously investigated for sinew repair with the long-term aim of repopulating the structure with autologous cells. Although this procedure shows promise, the demand for donor scaffolds will always outweigh supply. Here, we report the fabrication of fibrin-based tissue-engineered sinews, which can be decellularised, dehydrated and stored. The sinews may then be rehydrated and repopulated with an autologous cell population. In addition to enabling production of patient-specific implants, interestingly, the process of combined decellularisation, dehydration and rehydration enhanced the mechanical properties of the sinew. The treated sinews exhibited a 2.6-fold increase in maximum load and 8-fold increase in ultimate tensile strength when compared with the control group (p < 0.05 in both cases). PMID:24904729

  9. Incinerator ash bill supported by ASME (American Society of Mechanical Engineers)

    SciTech Connect

    Not Available

    1989-08-01

    Municipal waste combustion facilities must be retained as an option for solving this nation's total solid waste management problems, John W. Norton, representing the Solid Waste Processing Division of the American Society of Mechanical Engineers (ASME), told the House Subcommittee on Transportation and Hazardous Materials. Norton testified on H.R. 2162, the Municipal Solid Waste Incineration Act of 1989. The bill would ensure environmentally sound disposal of incinerator ash residues while improving public confidence in the disposal of municipal waste through combustion. Although agreeing that the EPA should issue guidelines removing certain items (such as batteries) from the trash to be burned, Norton urged additional research to determine the impact of such actions. He cautioned that toxic components such as heavy metals are pervasive in wastes and, therefore, it is unlikely that removal of a few items will significantly affect the quality of either ash or air emissions. We believe recycling and reuse of municipal solid waste incinerator ash offers great promise to reduce the need for disposal in landfills, testified Norton. He urged that the bill authorize a substantial research program on ash recycling and reuse at EPA.

  10. Understanding dental CAD/CAM for restorations--accuracy from a mechanical engineering viewpoint.

    PubMed

    Tapie, Laurent; Lebon, Nicolas; Mawussi, Bernardin; Fron-Chabouis, Hélène; Duret, Francois; Attal, Jean-Pierre

    2015-01-01

    As is the case in the field of medicine, as well as in most areas of daily life, digital technology is increasingly being introduced into dental practice. Computer-aided design/ computer-aided manufacturing (CAD/CAM) solutions are available not only for chairside practice but also for creating inlays, crowns, fixed partial dentures (FPDs), implant abutments, and other dental prostheses. CAD/CAM dental practice can be considered as the handling of devices and software processing for the almost automatic design and creation of dental restorations. However, dentists who want to use dental CAD/CAM systems often do not have enough information to understand the variations offered by such technology practice. Knowledge of the random and systematic errors in accuracy with CAD/CAM systems can help to achieve successful restorations with this technology, and help with the purchasing of a CAD/CAM system that meets the clinical needs of restoration. This article provides a mechanical engineering viewpoint of the accuracy of CAD/ CAM systems, to help dentists understand the impact of this technology on restoration accuracy. PMID:26734668

  11. An Engineered Kinetic Amplification Mechanism for Single Nucleotide Variant Discrimination by DNA Hybridization Probes.

    PubMed

    Chen, Sherry Xi; Seelig, Georg

    2016-04-20

    Even a single-nucleotide difference between the sequences of two otherwise identical biological nucleic acids can have dramatic functional consequences. Here, we use model-guided reaction pathway engineering to quantitatively improve the performance of selective hybridization probes in recognizing single nucleotide variants (SNVs). Specifically, we build a detection system that combines discrimination by competition with DNA strand displacement-based catalytic amplification. We show, both mathematically and experimentally, that the single nucleotide selectivity of such a system in binding to single-stranded DNA and RNA is quadratically better than discrimination due to competitive hybridization alone. As an additional benefit the integrated circuit inherits the property of amplification and provides at least 10-fold better sensitivity than standard hybridization probes. Moreover, we demonstrate how the detection mechanism can be tuned such that the detection reaction is agnostic to the position of the SNV within the target sequence. in contrast, prior strand displacement-based probes designed for kinetic discrimination are highly sensitive to position effects. We apply our system to reliably discriminate between different members of the let-7 microRNA family that differ in only a single base position. Our results demonstrate the power of systematic reaction network design to quantitatively improve biotechnology. PMID:27010123

  12. Training mechanical engineering students to utilize biological inspiration during product development.

    PubMed

    Bruck, Hugh A; Gershon, Alan L; Golden, Ira; Gupta, Satyandra K; Gyger, Lawrence S; Magrab, Edward B; Spranklin, Brent W

    2007-12-01

    The use of bio-inspiration for the development of new products and devices requires new educational tools for students consisting of appropriate design and manufacturing technologies, as well as curriculum. At the University of Maryland, new educational tools have been developed that introduce bio-inspired product realization to undergraduate mechanical engineering students. These tools include the development of a bio-inspired design repository, a concurrent fabrication and assembly manufacturing technology, a series of undergraduate curriculum modules and a new senior elective in the bio-inspired robotics area. This paper first presents an overview of the two new design and manufacturing technologies that enable students to realize bio-inspired products, and describes how these technologies are integrated into the undergraduate educational experience. Then, the undergraduate curriculum modules are presented, which provide students with the fundamental design and manufacturing principles needed to support bio-inspired product and device development. Finally, an elective bio-inspired robotics project course is present, which provides undergraduates with the opportunity to demonstrate the application of the knowledge acquired through the curriculum modules in their senior year using the new design and manufacturing technologies. PMID:18037728

  13. Reversible Tuning of Individual Carbon Nanotube Mechanical Properties via Defect Engineering.

    PubMed

    Zhang, Bin; Zhao, Longze; Cheng, Yong; Golberg, Dmitri; Wang, Ming-Sheng

    2016-08-10

    The structural defects that inevitably exist in real-world carbon nanotubes (CNTs) are generally considered undesirable because they break the structural perfection and may result in drastically degraded CNT properties. On the other hand, the deliberate defect introduction can provide a possibility to tailor the tube mechanical properties. Herein, we present a fully controllable technique to handle defects by using in situ transmission electron microscopy (TEM). Young's modulus, quality factor of the resonation and tensile strength of CNTs can be controllably, reversibly, and repeatedly tuned. Parallel high-resolution visualizing of structural defects suggests that the property tuning cycles are primarily attributed to the reversible conversion of defects at the atomic scale: the defects are created in the form of vacancies and interstitials under electron irradiation, and they vanish through the recombination via current-induced annealing. For applications, such as reversible frequency-tuned CNT resonators, this defect-engineering technique is demonstrated to be uniquely precise; the frequency may be tuned with 0.1%/min accuracy, improved by 1 order of magnitude compared with the existing approaches. We believe that these results will be highly valuable in a variety of property-tunable CNT-based composites and devices. PMID:27454869

  14. Understanding dental CAD/CAM for restorations - dental milling machines from a mechanical engineering viewpoint.

    PubMed

    Lebon, Nicolas; Tapie, Laurent; Duret, Francois; Attal, Jean-Pierre

    2016-01-01

    Nowadays, dental numerical controlled (NC) milling machines are available for dental laboratories (labside solution) and dental production centers. This article provides a mechanical engineering approach to NC milling machines to help dental technicians understand the involvement of technology in digital dentistry practice. The technical and economic criteria are described for four labside and two production center dental NC milling machines available on the market. The technical criteria are focused on the capacities of the embedded technologies of milling machines to mill prosthetic materials and various restoration shapes. The economic criteria are focused on investment cost and interoperability with third-party software. The clinical relevance of the technology is discussed through the accuracy and integrity of the restoration. It can be asserted that dental production center milling machines offer a wider range of materials and types of restoration shapes than labside solutions, while labside solutions offer a wider range than chairside solutions. The accuracy and integrity of restorations may be improved as a function of the embedded technologies provided. However, the more complex the technical solutions available, the more skilled the user must be. Investment cost and interoperability with third-party software increase according to the quality of the embedded technologies implemented. Each private dental practice may decide which fabrication option to use depending on the scope of the practice. PMID:27274561

  15. Intracellular Uptake: A Possible Mechanism for Silver Engineered Nanoparticle Toxicity to a Freshwater Alga Ochromonas danica

    PubMed Central

    Miao, Ai-Jun; Luo, Zhiping; Chen, Chi-Shuo; Chin, Wei-Chun; Santschi, Peter H.; Quigg, Antonietta

    2010-01-01

    The behavior and toxicity of silver engineered nanoparticles (Ag-ENs) to the mixotrophic freshwater alga Ochromonas danica were examined in the present study to determine whether any other mechanisms are involved in their algal toxicity besides Ag+ liberation outside the cells. Despite their good dispersability, the Ag-ENs were found to continuously aggregate and dissolve rapidly. When the initial nanoparticle concentration was lower than 10 µM, the total dissolved Ag+ concentration ([Ag+]T) in the suspending media reached its maximum after 1 d and then decreased suggesting that Ag+ release might be limited by the nanoparticle surface area under these conditions. Furthermore, Ag-EN dissolution extent remarkably increased in the presence of glutathione. In the Ag-EN toxicity experiment, glutathione was also used to eliminate the indirect effects of Ag+ that was released. However, remarkable toxicity was still observed although the free Ag+ concentration in the media was orders of magnitude lower than the non-observed effect concentration of Ag+ itself. Such inhibitive effects were mitigated when more glutathione was added, but could never be completely eliminated. Most importantly, we demonstrate, for the first time, that Ag-ENs can be taken in and accumulated inside the algal cells, where they exerted their toxic effects. Therefore, nanoparticle internalization may be an alternative pathway through which algal growth can be influenced. PMID:21203552

  16. Energy efficiency in the U.S. residential sector: An engineering and economic assessment of opportunities for large energy savings and greenhouse gas emissions reductions

    NASA Astrophysics Data System (ADS)

    Lima de Azevedo, Ines Margarida

    Energy efficiency and conservation is a very promising part of a portfolio of the needed strategies to mitigate climate change. Several technologies and energy efficiency measures in the residential sector offer potential for large energy savings. However, while energy efficiency options are currently considered as a means of reducing carbon emissions, there is still large uncertainty about the effect of such measures on overall carbon savings. The first part of this thesis provides a national assessment of the energy efficiency potential in the residential sector under several different scenarios, which include the perspectives of different economic agents (consumers, utilities, ESCOs, and a society). The scenarios also include maximizing energy, electricity or carbon dioxide savings. The second part of this thesis deals with a detailed assessment of the potential for white-light LEDs for energy and carbon dioxide savings in the U.S. commercial and residential sectors. Solid-state lighting shows great promise as a source of efficient, affordable, color-balanced white light. Indeed, assuming market discount rates, the present work demonstrates that white solid-state lighting already has a lower levelized annual cost (LAC) than incandescent bulbs and that it will be lower than that of the most efficient fluorescent bulbs by the end of this decade. However, a large literature indicates that households do not make their decisions in terms of simple expected economic value. The present analysis shows that incorporating the findings from literature on high implicit discount rates from households when performing decisions towards efficient technologies delays the adoption of white LEDs by a couple of years. After a review of the technology, the present work compares the electricity consumption, carbon emissions and cost-effectiveness of current lighting technologies, when accounting for expected performance evolution through 2015. Simulations of lighting electricity

  17. Development of Kinetic Mechanisms for Next-Generation Fuels and CFD Simulation of Advanced Combustion Engines

    SciTech Connect

    Pitz, William J.; McNenly, Matt J.; Whitesides, Russell; Mehl, Marco; Killingsworth, Nick J.; Westbrook, Charles K.

    2015-12-17

    Predictive chemical kinetic models are needed to represent next-generation fuel components and their mixtures with conventional gasoline and diesel fuels. These kinetic models will allow the prediction of the effect of alternative fuel blends in CFD simulations of advanced spark-ignition and compression-ignition engines. Enabled by kinetic models, CFD simulations can be used to optimize fuel formulations for advanced combustion engines so that maximum engine efficiency, fossil fuel displacement goals, and low pollutant emission goals can be achieved.

  18. Development of a short length combustor for a supersonic cruise turbofan engine using a 90 deg sector of a full annulus

    NASA Technical Reports Server (NTRS)

    Clements, T. R.

    1972-01-01

    A performance development program has been conducted on a short length, double-annular, ram-induction combustor. The combustor was designed for a large augmented turbofan engine capable of sustained flight speeds up to Mach 3.0. Performance tests were conducted at an inlet temperature and Mach number simulating engine sea level takeoff conditions. At the design temperature rise of 1600 F, combustion efficiency was 100%, pattern factor was 0.20, and combined diffuser-combustor pressure loss was 4.4% or 1.12 times the diffuser inlet velocity head. A temperature rise in excess of 2400 F with a combustion efficiency of 94% was demonstrated.

  19. Environmental and Mechanical Stability of Environmental Barrier Coated SA Tyrannohex SiC Composites Under Simulated Turbine Engine Environments

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Halbig, Michael Charles; Sing, Mrityunjay

    2014-01-01

    The environmental stability and thermal gradient cyclic durability performance of SA Tyrannohex composites were investigated for turbine engine component applications. The work has been focused on investigating the combustion rig recession, cyclic thermal stress resistance and thermomechanical low cycle fatigue of uncoated and environmental barrier coated Tyrannohex SiC SA composites in simulated turbine engine combustion water vapor, thermal gradients, and mechanical loading conditions. Flexural strength degradations have been evaluated, and the upper limits of operating temperature conditions for the SA composite material systems are discussed based on the experimental results.

  20. Mechanical Engineering at RWTH Aachen University: Professional Curriculum Development and Teacher Training

    ERIC Educational Resources Information Center

    Henning, Klaus; Bornefeld, Gero; Brall, Stefan

    2007-01-01

    This paper offers a multi-perspective view on engineering education at RWTH Aachen University: curriculum design, examples of newly developed teaching methods for engineering curricula, and teaching competencies and teacher qualification. It is based on the theories of student-centred learning, project learning, social skills, etc., but the paper…

  1. Direct Measurement and Evaluation for Mechanical Engineering Programme Outcomes: Impact on Continuous Improvement

    ERIC Educational Resources Information Center

    Tahir, Mohd Faizal Mat; Khamis, Nor Kamaliana; Wahid, Zaliha; Ihsan, Ahmad Kamal Ariffin Mohd; Ghani, Jaharah Ab; Sabri, Mohd Anas Mohd; Sajuri, Zainuddin; Abdullah, Shahrum; Sulong, Abu Bakar

    2013-01-01

    Universiti Kebangsaan Malaysia (UKM) is a research university that continuously undergoes an audit and accreditation process for the management of its courses. The Faculty of Engineering and the Built Environment (FKAB) is subjected to such processes, one of them is the auditing conducted by the Engineering Accreditation Council (EAC), which gives…

  2. The Use of Physical and Virtual Manipulatives in an Undergraduate Mechanical Engineering (Dynamics) Course

    ERIC Educational Resources Information Center

    Pan, Edward A.

    2013-01-01

    Science, technology, engineering, and mathematics (STEM) education is a national focus. Engineering education, as part of STEM education, needs to adapt to meet the needs of the nation in a rapidly changing world. Using computer-based visualization tools and corresponding 3D printed physical objects may help nontraditional students succeed in…

  3. Using the van Hiele K-12 Geometry Learning Theory to Modify Engineering Mechanics Instruction

    ERIC Educational Resources Information Center

    Sharp, Janet M.; Zachary, Loren W.

    2004-01-01

    Engineering students use spatial thinking when examining diagrams or models to study structure design. It is expected that most engineering students have solidified spatial thinking skills during K-12 schooling. However, according to what we know about geometry learning and teaching, spatial thinking probably needs to be explicitly taught within…

  4. A Case for the Need of Using Scaffolding Methods in Teaching Introductory, Fundamental Engineering Mechanics Classes

    ERIC Educational Resources Information Center

    Boylan-Ashraf, Peggy C.; Freeman, Steven A.; Shelley, Mack C.

    2015-01-01

    In the past ten years, engineering classrooms have seen an exponential growth in the use of technology, more than during any other previous decade. Unprecedented advancements, such as the advent of innovative gadgets and fundamental instructional alterations in engineering classrooms, have introduced changes in both teaching and learning. Student…

  5. Wear mechanism and wear prevention in coal-fueled diesel engines

    SciTech Connect

    Schwalb, J.A.

    1991-06-01

    Contamination of the lube-oil with hard abrasive particles leads to a three-body abrasive wear mechanism that highly accelerates piston ring/cylinder liner wear in coal-fueled diesel engines. One approach to reducing that wear is to modify the size and orientation of surface asperities on the cylinder to enhance the formation of a hydrodynamic film, and to provide avenues of escape for particles that would otherwise be trapped in the wear zone. Another approach is to introduce additives into the contaminated lube-oil that further enhance hydrodynamic film formation, form chemical films on the wearing surfaces, or form films on the contaminant particles. This work focuses on defining the effects of cylinder liner surface finish, various configurations of slots in the cylinder liner surface, and various additives in the contaminated lube-oil on the wear process. Wear tests were initiated in a bench apparatus using coal-ash contaminated lube-oil to test the various wear configurations. The results of these tests indicate that the formation of a hydrodynamic film between the ring and cylinder specimens is enhanced by increasing surface roughness, and by orienting the surface asperities normal to the direction of ring travel but modifications to the cylinder liner surface did not greatly reduce the wear rate. Additives to the lubricant seemed to have a much more significant effect on wear, with a dispersant additive highly accelerating the wear, while a detergent additive was able to reduce the wear almost to the rate achieved where there was no contaminant.

  6. Thermo-mechanical efficiency of the bimetallic strip heat engine at the macro-scale and micro-scale

    NASA Astrophysics Data System (ADS)

    Arnaud, A.; Boughaleb, J.; Monfray, S.; Boeuf, F.; Cugat, O.; Skotnicki, T.

    2015-10-01

    Bimetallic strip heat engines are energy harvesters that exploit the thermo-mechanical properties of bistable bimetallic membranes to convert heat into mechanical energy. They thus represent a solution to transform low-grade heat into electrical energy if the bimetallic membrane is coupled with an electro-mechanical transducer. The simplicity of these devices allows us to consider their miniaturization using MEMS fabrication techniques. In order to design and optimize these devices at the macro-scale and micro-scale, this article proposes an explanation of the origin of the thermal snap-through by giving the expressions of the constitutive equations of composite beams. This allows us to evaluate the capability of bimetallic strips to convert heat into mechanical energy whatever their size is, and to give the theoretical thermo-mechanical efficiencies which can be obtained with these harvesters.

  7. A Phenomenological Model for Mechanically Mediated Growth, Remodeling, Damage, and Plasticity of Gel-Derived Tissue Engineered Blood Vessels

    PubMed Central

    Raykin, Julia; Rachev, Alexander I.

    2011-01-01

    Mechanical stimulation has been shown to dramatically improve mechanical and functional properties of gel-derived tissue engineered blood vessels (TEBVs). Adjusting factors such as cell source, type of extracellular matrix, cross-linking, magnitude, frequency, and time course of mechanical stimuli (among many other factors) make interpretation of experimental results challenging. Interpretation of data from such multifactor experiments requires modeling. We present a modeling framework and simulations for mechanically mediated growth, remodeling, plasticity, and damage of gel-derived TEBVs that merge ideas from classical plasticity, volumetric growth, and continuum damage mechanics. Our results are compared with published data and suggest that this model framework can predict the evolution of geometry and material behavior under common experimental loading scenarios. PMID:19831486

  8. Assessment of the mechanics of a tissue-engineered rat trachea in an image-processing environment

    PubMed Central

    da Silva, Thiago Henrique Gomes; Pazetti, Rogerio; Aoki, Fabio Gava; Cardoso, Paulo Francisco Guerreiro; Valenga, Marcelo Henrique; Deffune, Elenice; Evaristo, Thaiane; Pêgo-Fernandes, Paulo Manuel; Moriya, Henrique Takachi

    2014-01-01

    OBJECTIVES: Despite the recent success regarding the transplantation of tissue-engineered airways, the mechanical properties of these grafts are not well understood. Mechanical assessment of a tissue-engineered airway graft before implantation may be used in the future as a predictor of function. The aim of this preliminary work was to develop a noninvasive image-processing environment for the assessment of airway mechanics. METHOD: Decellularized, recellularized and normal tracheas (groups DECEL, RECEL, and CONTROL, respectively) immersed in Krebs-Henseleit solution were ventilated by a small-animal ventilator connected to a Fleisch pneumotachograph and two pressure transducers (differential and gauge). A camera connected to a stereomicroscope captured images of the pulsation of the trachea before instillation of saline solution and after instillation of Krebs-Henseleit solution, followed by instillation with Krebs-Henseleit with methacholine 0.1 M (protocols A, K and KMCh, respectively). The data were post-processed with computer software and statistical comparisons between groups and protocols were performed. RESULTS: There were statistically significant variations in the image measurements of the medial region of the trachea between the groups (two-way analysis of variance [ANOVA], p<0.01) and of the proximal region between the groups and protocols (two-way ANOVA, p<0.01). CONCLUSIONS: The technique developed in this study is an innovative method for performing a mechanical assessment of engineered tracheal grafts that will enable evaluation of the viscoelastic properties of neo-tracheas prior to transplantation. PMID:25029584

  9. The effect of tissue-engineered cartilage biomechanical and biochemical properties on its post-implantation mechanical behavior.

    PubMed

    Khoshgoftar, Mehdi; Wilson, Wouter; Ito, Keita; van Donkelaar, Corrinus C

    2013-01-01

    The insufficient load-bearing capacity of today's tissue-engineered (TE) cartilage limits its clinical application. Focus has been on engineering cartilage with enhanced mechanical stiffness by reproducing native biochemical compositions. More recently, depth dependency of the biochemical content and the collagen network architecture has gained interest. However, it is unknown whether the mechanical performance of TE cartilage would benefit more from higher content of biochemical compositions or from achieving an appropriate collagen organization. Furthermore, the relative synthesis rate of collagen and proteoglycans during the TE process may affect implant performance. Such insights would assist tissue engineers to focus on those aspects that are most important. The aim of the present study is therefore to elucidate the relative importance of implant ground substance stiffness, collagen content, and collagen architecture of the implant, as well as the synthesis rate of the biochemical constituents for the post-implantation mechanical behavior of the implant. We approach this by computing the post-implantation mechanical conditions using a composition-based fibril-reinforced poro-viscoelastic swelling model of the medial tibia plateau. Results show that adverse implant composition and ultrastructure may lead to post-implantation excessive mechanical loads, with collagen orientation being the most critical variable. In addition, we predict that a faster synthesis rate of proteoglycans compared to that of collagen during TE culture may result in excessive loads on collagen fibers post-implantation. This indicates that even with similar final contents, constructs may behave differently depending on their development. Considering these aspects may help to engineer TE cartilage implants with improved survival rates. PMID:22389193

  10. Quiet Clean Short-haul Experimental Engine (QCSEE). Ball spline pitch change mechanism design report

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Detailed design parameters are presented for a variable-pitch change mechanism. The mechanism is a mechanical system containing a ball screw/spline driving two counteracting master bevel gears meshing pinion gears attached to each of 18 fan blades.

  11. Understanding dental CAD/CAM for restorations - dental milling machines from a mechanical engineering viewpoint. Part A: chairside milling machines.

    PubMed

    Lebon, Nicolas; Tapie, Laurent; Duret, Francois; Attal, Jean-Pierre

    2016-01-01

    The dental milling machine is an important device in the dental CAD/CAM chain. Nowadays, dental numerical controlled (NC) milling machines are available for dental surgeries (chairside solution). This article provides a mechanical engineering approach to NC milling machines to help dentists understand the involvement of technology in digital dentistry practice. First, some technical concepts and definitions associated with NC milling machines are described from a mechanical engineering viewpoint. The technical and economic criteria of four chairside dental NC milling machines that are available on the market are then described. The technical criteria are focused on the capacities of the embedded technologies of these milling machines to mill both prosthetic materials and types of shape restorations. The economic criteria are focused on investment costs and interoperability with third-party software. The clinical relevance of the technology is assessed in terms of the accuracy and integrity of the restoration. PMID:27027102

  12. Critical design factors for sector transport maintenance in DEMO

    NASA Astrophysics Data System (ADS)

    Utoh, Hiroyasu; Someya, Youji; Tobita, Kenji; Asakura, Nobuyuki; Hoshino, Kazuo; Nakamura, Makoto

    2013-12-01

    This paper mainly focuses on a sector transport maintenance scheme from the aspects of high plant availability. In this study, three different maintenance schemes are considered based on (1) the number of maintenance ports and (2) the insertion direction. The design study clarifies critical design factors and key engineering issues on the maintenance scheme: (1) how to support an enormous overturning force of the toroidal field coils in the large open port for sector transport and (2) define the transferring mechanism of sectors in the vacuum vessel. On reviewing these assessment factors, the sector transport using a limited number of horizontal maintenance ports is found to be a more realistic maintenance scheme. In addition, evaluating maintenance scenarios under high decay heat is proposed for the first time. The key design factors are the cool-down time in the reactor and the cooling method in the maintenance scheme to keep components under operational temperature. Based on one-dimensional heat conduction analysis, after one month cool-down time, each sector of SlimCS could be transported to the hot cell facility by gas cooling.

  13. Surface Zone Articular Chondrocytes Modulate the Bulk and Surface Mechanical Properties of the Tissue-Engineered Cartilage

    PubMed Central

    Peng, Gordon; McNary, Sean M.; Athanasiou, Kyriacos A.

    2014-01-01

    The central hypothesis of functional tissue engineering is that an engineered construct can serve as a viable replacement tissue in vivo by replicating the structure and function of native tissue. In the case of articular cartilage, this requires the reproduction of the bulk mechanical and surface lubrication properties of native hyaline cartilage. Cartilage tissue engineering has primarily focused on achieving the bulk mechanical properties of native cartilage such as the compressive aggregate modulus and tensile strength. A scaffold-free self-assembling process has been developed that produces engineered cartilage with compressive properties approaching native tissue levels. Thus, the next step in this process is to begin addressing the friction coefficient and wear properties of these engineered constructs. The superficial zone protein (SZP), also known as lubricin or PRG4, is a boundary mode lubricant that is synthesized by surface zone (SZ) articular chondrocytes. Under conditions of high loading and low sliding speeds, SZP reduces friction and wear at the articular surface. The objective of this investigation was to determine whether increasing the proportion of SZ chondrocytes in cartilage constructs, in the absence of external stimuli such as growth factors and mechanical loading, would enhance the secretion of SZP and improve their frictional properties. In this study, cartilage constructs were engineered through a self-assembling process with varying ratios of SZ and middle zone (MZ) chondrocytes (SZ:MZ): 0:100, 25:75, 50:50, 75:25, and 100:0. Constructs containing different ratios of SZ and MZ chondrocytes did not significantly differ in the glycosaminoglycan composition or compressive aggregate modulus. In contrast, tensile properties and collagen content were enhanced in nearly all constructs containing greater amounts of SZ chondrocytes. Increasing the proportion of SZ chondrocytes had the hypothesized effect of improving the synthesis and secretion

  14. Mechanical properties and cellular response of novel electrospun nanofibers for ligament tissue engineering: Effects of orientation and geometry.

    PubMed

    Pauly, Hannah M; Kelly, Daniel J; Popat, Ketul C; Trujillo, Nathan A; Dunne, Nicholas J; McCarthy, Helen O; Haut Donahue, Tammy L

    2016-08-01

    Electrospun nanofibers are a promising material for ligamentous tissue engineering, however weak mechanical properties of fibers to date have limited their clinical usage. The goal of this work was to modify electrospun nanofibers to create a robust structure that mimics the complex hierarchy of native tendons and ligaments. The scaffolds that were fabricated in this study consisted of either random or aligned nanofibers in flat sheets or rolled nanofiber bundles that mimic the size scale of fascicle units in primarily tensile load bearing soft musculoskeletal tissues. Altering nanofiber orientation and geometry significantly affected mechanical properties; most notably aligned nanofiber sheets had the greatest modulus; 125% higher than that of random nanofiber sheets; and 45% higher than aligned nanofiber bundles. Modifying aligned nanofiber sheets to form aligned nanofiber bundles also resulted in approximately 107% higher yield stresses and 140% higher yield strains. The mechanical properties of aligned nanofiber bundles were in the range of the mechanical properties of the native ACL: modulus=158±32MPa, yield stress=57±23MPa and yield strain=0.38±0.08. Adipose derived stem cells cultured on all surfaces remained viable and proliferated extensively over a 7 day culture period and cells elongated on nanofiber bundles. The results of the study suggest that aligned nanofiber bundles may be useful for ligament and tendon tissue engineering based on their mechanical properties and ability to support cell adhesion, proliferation, and elongation. PMID:27082129

  15. Nanodevices for applications in life sciences and engineering; Fabrication and mechanical characterization

    NASA Astrophysics Data System (ADS)

    Singh, Gurpreet

    Fabrication and mechanical characterization of novel nanometer scale devices for application in life sciences and engineering has been realized. Two nanodevices were developed and tested during the course of this study: one is a prototype microtome knife for sectioning biological materials, made by welding a multiwall nanotube across the gap between two sharpened tungsten needles. The other is a nanotube/sphere device for use as a nanonewton force sensor. Both devices were fabricated using a piezoelectric-based 3-D manipulator under direct view in a scanning electron microscope (SEM). Mechanical characterization of the prototype microtome knife was done by performing load tests using an atomic force microscope (AFM) cantilever inside a SEM. Initial tests indicated a maximum breaking force of 1.4 muN. In situ cutting experiments on epon resin (biological cell embedding material) have revealed indentations made by pressure from nanotube in the microtome knife. In an effort to obtain a thinner nano-knife, an individual free standing nanotube was exposed to the 248 nm beam from a KrF excimer laser. The laser treatment resulted in selective exfoliation of amorphous contamination layer surrounding the multiwalled carbon nanotube (MWCNT). The results were confirmed by comparing transmission electron microscopy (TEM) images of the nanotube before and after the exposure. The nanotube/sphere device consists of a polystyrene microsphere (4-15 mum in diameter) attached to a MWCNT (5-50 mum long) whose other end is attached to a microscopy probe. The force vs. deflection behavior of this device was calibrated for varying nanotube dimensions. Calibration curves indicate forces in the range of (10-8 to 10-9) N for nantube length in the range (8 to 15) mum. The device will be used for studying deformation behavior of sensory hair bundles. The bending modulus calculated from calibration tests for individual nanotubes ranged 11-59 GPa, these values agree with values available in

  16. A chondroitinase-ABC and TGF-β1 treatment regimen for enhancing the mechanical properties of tissue engineered fibrocartilage

    PubMed Central

    MacBarb, Regina F.; Makris, Eleftherios A.; Hu, Jerry C.; Athanasiou, Kyriacos A.

    2012-01-01

    The development of functionally equivalent fibrocartilage remains elusive despite efforts to engineer tissues such as the knee menisci, intervertebral disc, and TMJ disc. Attempts to engineer these structures often fail to create tissues with mechanical properties on par with native tissue, resulting in constructs unsuitable for clinical applications. The objective of this study was to engineer a spectrum of biomimetic fibrocartilages representative of the distinct functional properties found in native tissues. Using the self-assembly process, different co-cultures of meniscus cells (MCs) and articular chondrocytes (ACs) were seeded into agarose wells and treated with the catabolic agent chondroitinase-ABC (C-ABC) and the anabolic agent transforming growth factor-β1 (TGF-β1) via a two-factor (cell ratio and bioactive treatment), full factorial study design. Application of both C-ABC and TGF-β1 resulted in a beneficial or positive increase in the collagen content of treated constructs compared to controls. Significant increases in both the collagen density and fiber diameter were also seen with this treatment, increasing these values 32% and 15%, respectively, over control values. Mechanical testing found the combined bioactive treatment to synergistically increase the Young’s modulus and ultimate tensile strength of the engineered fibrocartilages compared to controls, with values reaching the lower spectrum of those found in native tissues. Together, these data demonstrate that C-ABC and TGF-β1 interact to develop a denser collagen matrix better able to withstand tensile loading. This study highlights a way to optimize the tensile properties of engineered fibrocartilage using a biochemical and biophysical agent together to create distinct fibrocartilages with functional properties mimicking those of native tissue. PMID:23041782

  17. Randomised Controlled Trial of a Parenting Intervention in the Voluntary Sector for Reducing Child Conduct Problems: Outcomes and Mechanisms of Change

    ERIC Educational Resources Information Center

    Gardner, Frances; Burton, Jennifer; Klimes, Ivana

    2006-01-01

    Background: To test effectiveness of a parenting intervention, delivered in a community-based voluntary-sector organisation, for reducing conduct problems in clinically-referred children. Methods: Randomised controlled trial, follow-up at 6, 18 months, assessors blind to treatment status. Participants--76 children referred for conduct problems,…

  18. Gaseous core nuclear-driven engines featuring a self-shutoff mechanism to provide nuclear safety

    SciTech Connect

    Heidrich, J.; Pettibone, J.; Chow, Tze-Show; Condit, R.; Zimmerman, G.

    1991-11-01

    Nuclear driven engines are described that could be run in either pulsed or steady state modes. In the pulsed mode nuclear energy is released by fissioning of uranium or plutonium in a supercritical assembly of fuel and working gas. In a steady state mode a fuel-gas mixture is injected into a magnetic nozzle where it is compressed into a critical state and produces energy. Engine performance is modeled using a code that calculates hydrodynamics, fission energy production, and neutron transport self-consistently. Results are given demonstrating a large negative temperature coefficient that produces self-shutoff or control of energy production. Reduced fission product inventory and the self-shutoff provide inherent nuclear safety. It is expected that nuclear engine reactor units could be scaled up from about 100 MW{sub e}.

  19. Proceedings of the ninth international conference on offshore mechanics and Arctic engineering, 1990

    SciTech Connect

    Ayorinde, O.A.; Sodhi, D.S. ); Sinha, N.K. )

    1990-01-01

    The proceeding in this book is covered under the following headings: Arctic Structures and Operation Ice-Structure Interaction; Applied Ice Mechanics; Ice Properties; Ice Environment/Statistics; and Properties, Mechanics, and Analysis of Frozen Soil.

  20. ATS-6 engineering performance report. Volume:Program and systems summaries: Mechanical and thermal details

    NASA Technical Reports Server (NTRS)

    Wales, R. O. (Editor)

    1981-01-01

    The overall mission and spacecraft systems, testing, and operations are summarized. The mechanical subsystems are reviewed, encompassing mechanical design requirements; separation and deployment mechanisms; design and performance evaluation; and the television camera reflector monitor. Thermal control and contamination are discussed in terms of thermal control subsystems, design validation, subsystems performance, the advanced flight experiment, and the quartz-crystal microbalance contamination monitor.

  1. Determining the Mechanism of In-Service Cylinder Distortion in Aluminum Engine Blocks with Cast-In Gray Iron Liners

    NASA Astrophysics Data System (ADS)

    Lombardi, Anthony; Ravindran, Comondore; Sediako, Dimitry; MacKay, Robert

    2014-12-01

    In recent years, stringent government legislation on vehicle fuel efficiency has pushed the automotive industry to replace steel and cast iron power train components with light weight Al alloys. However, unlike their ferrous-based equivalents, Al-Si alloy engine blocks are prone to permanent dimensional distortion in critical locations such as the cylinder bore regions. Understanding the mechanisms that cause distortion will promote the use of Al alloys over ferrous alloys for power train applications and enable automotive manufacturers to meet emission standards and reduce fuel consumption. In this study, neutron diffraction was used to evaluate residual stress along the Al cylinder bridge and the gray cast iron liners of distorted and undistorted engine blocks. Microstructural analysis was carried out using OM, SEM, and TEM, while mechanical testing was accomplished via ambient and elevated temperature [~453 K (180 °C)] tensile testing. The results suggest that the distorted engine block had high tensile residual stress in the Al cylinder bridge, reaching a maximum of 170 MPa in the hoop direction, which triggered permanent dimensional distortion in the cylinders when exposed to service conditions. In addition, the middle of the cylinder had the highest magnitude of distortion since this region had a combination of high tensile residual stress (hoop stress of 150 MPa) and reduced strength compared with the bottom of the cylinder.

  2. Determining the Mechanism of In-Service Cylinder Distortion in Aluminum Engine Blocks with Cast-In Gray Iron Liners

    NASA Astrophysics Data System (ADS)

    Lombardi, Anthony; Ravindran, Comondore; Sediako, Dimitry; MacKay, Robert

    2014-09-01

    In recent years, stringent government legislation on vehicle fuel efficiency has pushed the automotive industry to replace steel and cast iron power train components with light weight Al alloys. However, unlike their ferrous-based equivalents, Al-Si alloy engine blocks are prone to permanent dimensional distortion in critical locations such as the cylinder bore regions. Understanding the mechanisms that cause distortion will promote the use of Al alloys over ferrous alloys for power train applications and enable automotive manufacturers to meet emission standards and reduce fuel consumption. In this study, neutron diffraction was used to evaluate residual stress along the Al cylinder bridge and the gray cast iron liners of distorted and undistorted engine blocks. Microstructural analysis was carried out using OM, SEM, and TEM, while mechanical testing was accomplished via ambient and elevated temperature [~453 K (180 °C)] tensile testing. The results suggest that the distorted engine block had high tensile residual stress in the Al cylinder bridge, reaching a maximum of 170 MPa in the hoop direction, which triggered permanent dimensional distortion in the cylinders when exposed to service conditions. In addition, the middle of the cylinder had the highest magnitude of distortion since this region had a combination of high tensile residual stress (hoop stress of 150 MPa) and reduced strength compared with the bottom of the cylinder.

  3. Engine Tune-Up Service. Unit 1: Battery and Cranking System. Posttests. Automotive Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Goodson-Roberts, Ludy; And Others

    This book of posttests is designed to accompany the Engine Tune-Up Service Student Guide for Unit 1, Battery and Cranking System. Focus of the posttests is the testing of the battery and cranking system. Four multiple choice posttests are provided, one for each of the performance objectives contained in the unit. (No answer keys are provided.)…

  4. Engine Tune-up Service. Unit 2: Charging System. Review Exercise Book. Automotive Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Richardson, Roger L.; Bacon, E. Miles

    This book of pretests and review exercises is designed to accompany the Engine Tune-Up Service Student Guide for Unit 2, Charging System, available separately as CE 031 208. Focus of the exercises and pretests is testing the charging system. Pretests and performance checklists are provided for each of the three performance objectives contained in…

  5. Engine Tune-up Service. Unit 2: Charging System. Posttests. Automotive Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Richardson, Roger L.; Bacon, E. Miles

    This book of posttests is designed to accompany the Engine Tune-Up Service Student Guide for Unit 2, Charging System, available separately as CE 031 208. Focus of the posttest is on the testing of the charging system. One multiple choice posttest is provided, that covers the three performance objectives contained in the unit. (No answer key is…

  6. Engine Tune-up Service. Unit 6: Emission Control Systems. 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 6, Emission Control Systems, available separately as CE 031 220. Focus of the exercises and pretests is inspecting, testing, and servicing emission control systems. Pretests and performance checklists are provided for each of the…

  7. Engine Tune-up Service. Unit 6: Emission Control Systems. Posttests. Automotive Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Morse, David T.; May, Theodore R.

    This book of posttests is designed to accompany the Engine Tune-Up Service Student Guide for Unit 6, Emission Control Systems, available separately as CE 031 220. Focus of the posttests is inspecting, testing, and servicing emission control systems. One multiple choice posttest is provided that covers the seven performance objectives contained in…

  8. The Effect of Curricular Activities on Learner Autonomy: The Perspective of Undergraduate Mechanical Engineering Students

    ERIC Educational Resources Information Center

    Duarte, M.; Leite, C.; Mouraz, A.

    2016-01-01

    This study researches how first-year engineering students perceived the influence of curricular activities on their own learning autonomy, measured with an adaptation of the Personal Responsibility Orientation to Self-direction in Learning Scale (PRO-SDLS). Participants were questioned to assess the influence of the teacher's role. The results…

  9. Engine Tune-Up Service. Unit 3: Primary 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 3, Primary Circuit, available separately as CE 031 211. Focus of the posttests is setting the primary ignition circuit. One multiple choice posttest is provided, covering the eight performance objectives contained in the unit. (No answer key is…

  10. 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…

  11. Engine Tune-Up Service. Unit 3: Primary 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 3, Primary Circuit, available separately as CE 031 211. Focus of the exercises and pretests is testing the primary ignition circuit. Pretests and performance checklists are provided for each of the eight performance objectives…

  12. 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…

  13. Microelectrical Mechanical Systems Flow Control Used to Manage Engine Face Distortion in Compact Inlet Systems

    NASA Technical Reports Server (NTRS)

    Anderson, Bernhard H.; Miller, Daniel N.

    1999-01-01

    Turbofan engine-face flow distortion is one of the most troublesome and least understood problems for designers of modern engine inlet systems. One concern is that there are numerous sources of flow-field distortion that are ingested by the inlet or generated within the inlet duct itself. Among these are: (1) flow separation at the cowl lip during in-flight maneuvering, (2) flow separation on the compression surfaces due to shock-wave/boundary layer interactions, (3) spillage of the fuselage boundary layer into the inlet duct, (4) ingestion of aircraft vortices and wakes emanating from upstream disturbances, and (5) strong secondary flow gradients and flow separation induced by wall curvature within the inlet duct itself. Most developing aircraft (including the B70, F-111, F-14, Mig-25, Tornado, and Airbus A300) have experienced one or more of these types of problems, particularly at high Mach numbers and/or extreme maneuver conditions when flow distortion at the engine face exceeded the allowable limits of the engine.

  14. Engineered biochar reclaiming phosphate from aqueous solutions: mechanisms and potential application as a slow-release fertilizer.

    PubMed

    Yao, Ying; Gao, Bin; Chen, Jianjun; Yang, Liuyan

    2013-08-01

    This work explored the potential application of an engineered biochar prepared from Mg-enriched tomato tissues to reclaim and reuse phosphate (P) from aqueous solution. Findings from batch sorption experiments suggested that, although sorption of P on the biochar was controlled by relatively slow kinetics, the maximum P sorption capacity of the biochar could reach >100 mg·g(-1). Mathematical modeling and postsorption characterization results indicated that the sorption was mainly controlled by two mechanisms: precipitation of P through chemical reaction with Mg particles and surface deposition of P on Mg crystals on biochar surfaces. Most of the P retained in the engineered biochar was bioavailable and could be released equally at multiple successive extractions. In addition, the P-laden biochar significantly stimulated grass seed germination and growth. These results suggested the postsorption biochar can be cycled back directly to soils as an effective slow-release P-fertilizer. PMID:23848524

  15. Biologically and mechanically driven design of an RGD-mimetic macroporous foam for adipose tissue engineering applications.

    PubMed

    Rossi, Eleonora; Gerges, Irini; Tocchio, Alessandro; Tamplenizza, Margherita; Aprile, Paola; Recordati, Camilla; Martello, Federico; Martin, Ivan; Milani, Paolo; Lenardi, Cristina

    2016-10-01

    Despite clinical treatments for adipose tissue defects, in particular breast tissue reconstruction, have certain grades of efficacy, many drawbacks are still affecting the long-term survival of new formed fat tissue. To overcome this problem, in the last decades, several scaffolding materials have been investigated in the field of adipose tissue engineering. However, a strategy able to recapitulate a suitable environment for adipose tissue reconstruction and maintenance is still missing. To address this need, we adopted a biologically and mechanically driven design to fabricate an RGD-mimetic poly(amidoamine) oligomer macroporous foam (OPAAF) for adipose tissue reconstruction. The scaffold was designed to fulfil three fundamental criteria: capability to induce cell adhesion and proliferation, support of in vivo vascularization and match of native tissue mechanical properties. Poly(amidoamine) oligomers were formed into soft scaffolds with hierarchical porosity through a combined free radical polymerization and foaming reaction. OPAAF is characterized by a high water uptake capacity, progressive degradation kinetics and ideal mechanical properties for adipose tissue reconstruction. OPAAF's ability to support cell adhesion, proliferation and adipogenesis was assessed in vitro using epithelial, fibroblast and endothelial cells (MDCK, 3T3L1 and HUVEC respectively). In addition, in vivo subcutaneous implantation in murine model highlighted OPAAF potential to support both adipogenesis and vessels infiltration. Overall, the reported results support the use of OPAAF as a scaffold for engineered adipose tissue construct. PMID:27428768

  16. Systems Engineering Lessons Learned from Solar Array Structures and Mechanisms Deployment

    NASA Technical Reports Server (NTRS)

    Vipavetz, Kevin; Kraft, Thomas

    2013-01-01

    This report has been developed by the National Aeronautics and Space Administration (NASA) Human Exploration and Operations Mission Directorate (HEOMD) Risk Management team in close coordination with the Engineering Directorate at LaRC. This document provides a point-in-time, cumulative, summary of actionable key lessons learned derived from the design project. Lessons learned invariably address challenges and risks and the way in which these areas have been addressed. Accordingly the risk management thread is woven throughout the document.

  17. Local and latitudinal variation in abundance: the mechanisms shaping the distribution of an ecosystem engineer

    PubMed Central

    Gonzalez, Angélica L.; Crawford, Kerri M.; Sanders, Nathan J.

    2013-01-01

    Ecological processes that determine the abundance of species within ecological communities vary across space and time. These scale-dependent processes are especially important when they affect key members of a community, such as ecosystem engineers that create shelter and food resources for other species. Yet, few studies have examined the suite of processes that shape the abundance of ecosystem engineers. Here, we evaluated the relative influence of temporal variation, local processes, and latitude on the abundance of an engineering insect—a rosette-galling midge, Rhopalomyia solidaginis (Diptera: Cecidomyiidae). Over a period of 3–5 years, we studied the density and size of galls across a suite of local experiments that manipulated genetic variation, soil nutrient availability, and the removal of other insects from the host plant, Solidago altissima (tall goldenrod). We also surveyed gall density within a single growing season across a 2,300 km latitudinal transect of goldenrod populations in the eastern United States. At the local scale, we found that host-plant genotypic variation was the best predictor of rosette gall density and size within a single year. We found that the removal of other insect herbivores resulted in an increase in gall density and size. The amendment of soil nutrients for four years had no effect on gall density, but galls were smaller in carbon-added plots compared to control and nitrogen additions. Finally, we observed that gall density varied several fold across years. At the biogeographic scale, we observed that the density of rosette gallers peaked at mid-latitudes. Using meta-analytic approaches, we found that the effect size of time, followed by host-plant genetic variation and latitude were the best predictors of gall density. Taken together, our study provides a unique comparison of multiple factors across different spatial and temporal scales that govern engineering insect herbivore density. PMID:23862102

  18. Wear mechanism and wear prevention in coal-fueled diesel engines

    SciTech Connect

    Wakenell, J.F.; Fritz, S.G.; Schwalb, J.A.

    1991-07-01

    Over the past several years, interest has arisen in the development of coal-fired diesel engines for the purpose of efficiently utilizing the extensive coal reserves in the United States, and therefore reducing dependence on foreign oil. One process, which is being considered for use in producing clean coal fuel products involves mild gasification. This process produces by-products which can be further refined and, when blended with neat diesel fuel, used as an engine fuel. The purpose of this task was to test a blend of this coal liquid and diesel fuel (referred to as coal-lite) in an engine, and determine if any detrimental results were observed. This was done by performing a back-to-back performance and emission test of neat diesel fuel and the coal-lite fuel, followed by a 500-hour test of the coal-lite fuel, and completed by a back-to-back performance and emission test of the coal-lite fuel and neat diesel fuel.

  19. Wear mechanism and wear prevention in coal-fueled diesel engines. Task 7, Extended wear testing

    SciTech Connect

    Wakenell, J.F.; Fritz, S.G.; Schwalb, J.A.

    1991-07-01

    Over the past several years, interest has arisen in the development of coal-fired diesel engines for the purpose of efficiently utilizing the extensive coal reserves in the United States, and therefore reducing dependence on foreign oil. One process, which is being considered for use in producing clean coal fuel products involves mild gasification. This process produces by-products which can be further refined and, when blended with neat diesel fuel, used as an engine fuel. The purpose of this task was to test a blend of this coal liquid and diesel fuel (referred to as coal-lite) in an engine, and determine if any detrimental results were observed. This was done by performing a back-to-back performance and emission test of neat diesel fuel and the coal-lite fuel, followed by a 500-hour test of the coal-lite fuel, and completed by a back-to-back performance and emission test of the coal-lite fuel and neat diesel fuel.

  20. Procedure for implementation of temperature-dependent mechanical property capability in the Engineering Analysis Language (EAL) system

    NASA Technical Reports Server (NTRS)

    Glass, David E.; Robinson, James C.

    1990-01-01

    A procedure is presented to allow the use of temperature dependent mechanical properties in the Engineering Analysis Language (EAL) System for solid structural elements. This is accomplished by including a modular runstream in the main EAL runstream. The procedure is applicable for models with multiple materials and with anisotropic properties, and can easily be incorporated into an existing EAL runstream. The procedure (which is applicable for EAL elastic solid elements) is described in detail, followed by a description of the validation of the routine. A listing of the EAL runstream used to validate the procedure is included in the Appendix.

  1. Lunar surface engineering properties experiment definition. Volume 2: Mechanics of rolling sphere-soil slope interaction

    NASA Technical Reports Server (NTRS)

    Hovland, H. J.; Mitchell, J. K.

    1971-01-01

    The soil deformation mode under the action of a rolling sphere (boulder) was determined, and a theory based on actual soil failure mechanism was developed which provides a remote reconnaissance technique for study of soil conditions using boulder track observations. The failure mechanism was investigated by using models and by testing an instrumented spherical wheel. The wheel was specifically designed to measure contact pressure, but it also provided information on the failure mechanism. Further tests included rolling some 200 spheres down sand slopes. Films were taken of the rolling spheres, and the tracks were measured. Implications of the results and reevaluation of the lunar boulder tracks are discussed.

  2. Silicon-based elementary particle tracking system: Materials science and mechanical engineering design

    SciTech Connect

    Miller, W.O.; Gamble, M.T.; Thompson, T.C.; Hanlon, J.A.

    1993-01-01

    Research and development of the mechanical, cooling, and structural design aspects of a silicon detector-based elementary particle tracking system has been performed. Achieving stringent system precision, stability, and mass requirements necessitated the use of graphite fiber-reinforced cyanate-ester (C-E) resins. Mechanical test results of the effects of butane, ionizing radiation, and a combination of both on the mechanical properties of these materials are presented, as well as progress on developing compression molding of an ultralightweight graphite composite ring structure and TV holography-based noninvasive evaluation.

  3. Silicon-based elementary particle tracking system: Materials science and mechanical engineering design

    SciTech Connect

    Miller, W.O.; Gamble, M.T.; Thompson, T.C.; Hanlon, J.A.

    1993-05-01

    Research and development of the mechanical, cooling, and structural design aspects of a silicon detector-based elementary particle tracking system has been performed. Achieving stringent system precision, stability, and mass requirements necessitated the use of graphite fiber-reinforced cyanate-ester (C-E) resins. Mechanical test results of the effects of butane, ionizing radiation, and a combination of both on the mechanical properties of these materials are presented, as well as progress on developing compression molding of an ultralightweight graphite composite ring structure and TV holography-based noninvasive evaluation.

  4. A Theoretical Mechanism of Szilard Engine Function in Nucleic Acids and the Implications for Quantum Coherence in Biological Systems

    SciTech Connect

    Matthew Mihelic, F.

    2010-12-22

    Nucleic acids theoretically possess a Szilard engine function that can convert the energy associated with the Shannon entropy of molecules for which they have coded recognition, into the useful work of geometric reconfiguration of the nucleic acid molecule. This function is logically reversible because its mechanism is literally and physically constructed out of the information necessary to reduce the Shannon entropy of such molecules, which means that this information exists on both sides of the theoretical engine, and because information is retained in the geometric degrees of freedom of the nucleic acid molecule, a quantum gate is formed through which multi-state nucleic acid qubits can interact. Entangled biophotons emitted as a consequence of symmetry breaking nucleic acid Szilard engine (NASE) function can be used to coordinate relative positioning of different nucleic acid locations, both within and between cells, thus providing the potential for quantum coherence of an entire biological system. Theoretical implications of understanding biological systems as such 'quantum adaptive systems' include the potential for multi-agent based quantum computing, and a better understanding of systemic pathologies such as cancer, as being related to a loss of systemic quantum coherence.

  5. Eleventh symposium on energy engineering sciences: Proceedings. Solid mechanics and processing: Analysis, measurement and characterization

    SciTech Connect

    Not Available

    1993-09-01

    The Eleventh Symposium on Energy Engineering Sciences was held on May 3--5, 1993, at the Argonne National Laboratory, Argonne, Illinois. These proceedings include the program, list of participants, and the papers that were presented during the eight technical sessions held at this meeting. This symposium was organized into eight technical sessions: Surfaces and interfaces; thermophysical properties and processes; inelastic behavior; nondestructive characterization; multiphase flow and thermal processes; optical and other measurement systems; stochastic processes; and large systems and control. Individual projects were processed separately for the databases.

  6. Hybrid metal-coordinate transient networks: using bio-inspired building blocks to engineer the mechanical properties of physical hydrogels

    NASA Astrophysics Data System (ADS)

    Grindy, Scott; Barrett, Devin; Messersmith, Phillip; Holten-Andersen, Niels

    2014-03-01

    Recently, metal-coordinate complex crosslinks have been suggested to contribute to the self-healing properties of mussel byssi. Two specific amino acid derivatives - 3,4 dihydroxy-L-phenylalanine (dopa) and histidine (his) - are known to form coordinate complexes with trivalent and divalent ions (respectively) in aqueous solutions. We show here that, by functionalizing poly(ethylene glycol) polymers with dopa and his we are (1) able to characterize the fundamental kinetics and energetics of each specific metal-ligand pair using small amplitude oscillatory shear rheology and (2) create hybrid networks using various mixtures of metals and ligands. From this information, we can design gels with specific target mechanical properties by tailoring the amounts and types of metal-ligand crosslinks present in the gel network, resulting in the ability to engineer the mechanical relaxation spectrum. This work provides basic understanding necessary to intelligently design materials which incorporate metal-ligand crosslinks in more complex architectures.

  7. Advanced Prop-fan Engine Technology (APET) single- and counter-rotation gearbox/pitch change mechanism

    NASA Technical Reports Server (NTRS)

    Reynolds, C. N.

    1985-01-01

    The preliminary design of advanced technology (1992) turboprop engines for single-rotation prop-fans and conceptual designs of pitch change mechanisms for single- and counter-rotation prop-fan application are discussed. The single-rotation gearbox is a split path, in-line configuration. The counter-rotation gearbox is an in-line, differential planetary design. The pitch change mechanisms for both the single- and counter-rotation arrangements are rotary/hydraulic. The advanced technology single-rotation gearbox yields a 2.4 percent improvement in aircraft fuel burn and a one percent improvement in operating cost relative to a current technology gearbox. The 1992 counter-rotation gearbox is 15 percent lighter, 15 percent more reliable, 5 percent lower in cost, and 45 percent lower in maintenance cost than the 1992 single-rotation gearbox. The pitch controls are modular, accessible, and external.

  8. Tuning mechanical performance of poly(ethylene glycol) and agarose interpenetrating network hydrogels for cartilage tissue engineering

    PubMed Central

    Rennerfeldt, DA; Renth, AN; Talata, Z; Gehrke, SH; Detamore, MS

    2013-01-01

    Hydrogels are attractive for tissue engineering applications due to their incredible versatility, but they can be limited in cartilage tissue engineering applications due to inadequate mechanical performance. In an effort to address this limitation, our team previously reported the drastic improvement in the mechanical performance of interpenetrating networks (IPNs) of poly(ethylene glycol) diacrylate (PEG-DA) and agarose relative to pure PEG-DA and agarose networks. The goal of the current study was specifically to determine the relative importance of PEG-DA concentration, agarose concentration, and PEG-DA molecular weight in controlling mechanical performance, swelling characteristics, and network parameters. IPNs consistently had compressive and shear moduli greater than the additive sum of either single network when compared to pure PEG-DA gels with a similar PEG-DA content. IPNs withstood a maximum stress of up to 4.0 MPa in unconfined compression, with increased PEG-DA molecular weight being the greatest contributing factor to improved failure properties. However, aside from failure properties, PEG-DA concentration was the most influential factor for the large majority of properties. Increasing the agarose and PEG-DA concentrations as well as the PEG-DA molecular weight of agarose/PEG-DA IPNs and pure PEG-DA gels improved moduli and maximum stresses by as much as an order of magnitude or greater compared to pure PEG-DA gels in our previous studies. Although the viability of encapsulated chondrocytes was not significantly affected by IPN formulation, glycosaminoglycan (GAG) content was significantly influenced, with a 12-fold increase over a three-week period in gels with a lower PEG-DA concentration. These results suggest that mechanical performance of IPNs may be tuned with partial but not complete independence from biological performance of encapsulated cells. PMID:23932504

  9. Thermal and mechanical analysis of major components for the advanced adiabatic diesel engine

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The proposed design for the light duty diesel is an in-line four cylinder spark assisted diesel engine mounted transversely in the front of the vehicle. The engine has a one piece cylinder head, with one intake valve and one exhaust valve per cylinder. A flat topped piston is used with a cylindrical combustion chamber recessed into the cylinder head directly under the exhaust valve. A single ceramic insert is cast into the cylinder head to insulate both the combustion chamber and the exhaust port. A similar ceramic insert is cast into the head to insulate the intake port. A ceramic faceplate is pressed into the combustion face of the head to insulate the face of the head from hot combustion gas. The valve seats are machined directly into the ceramic faceplate for the intake valve and into the ceramic exhaust pot insert for the exhaust valve. Additional ceramic applications in the head are the use of ceramic valve guides and ceramic insulated valves. The ceramic valve guides are press fit into the head and are used for increased wear resistance. The ceramic insulated valves are conventional valves with the valve faces plasma spray coated with ceramic for insulation.

  10. Resilin-like polypeptide-poly(ethylene gylcol) hybrid hydrogels for mechanically-demanding tissue engineering applications

    NASA Astrophysics Data System (ADS)

    McGann, Christopher Leland

    Technological progress in the life sciences and engineering has combined with important insights in the fields of biology and material science to make possible the development of biological substitutes which aim to restore function to damaged tissue. Numerous biomimetic hydrogels have been developed with the purpose of harnessing the regenerative capacity of cells and tissue through the rational deployment of biological signals. Aided by recombinant DNA technology and protein engineering methods, a new class of hydrogel precursor, the biosynthetic protein polymer, has demonstrated great promise towards the development of highly functional tissue engineering materials. In particular, protein polymers based upon resilin, a natural protein elastomer, have demonstrated outstanding mechanical properties that would have great value in soft tissue applications. This dissertation introduces hybrid hydrogels composed of recombinant resilin-like polypeptides (RLPs) cross-linked with multi-arm PEG macromers. Two different chemical strategies were employed to form RLP-PEG hydrogels: one utilized a Michael-type addition reaction between the thiols of cysteine residues present within the RLP and vinyl sulfone moieties functionalized on a multi-arm PEG macromer; the second system cross-links a norbornene-functionalized RLP with a thiol-functionalized multi-arm PEG macromer via a photoinitiated thiol-ene step polymerization. Oscillatory rheology and tensile testing confirmed the formation of elastic, resilient hydrogels in the RLP-PEG system cross-linked via Michael-type addition. These hydrogels supported the encapsulation and culture of both human aortic adventitial fibroblasts and human mesenchymal stem cells. Additionally, these RLP-PEG hydrogels exhibited phase separation behavior during cross-linking that led to the formation of a heterogeneous microstructure. Degradation could be triggered through incubation with matrix metalloproteinase. Photocross-linking was conferred to

  11. Lung stress, strain, and energy load: engineering concepts to understand the mechanism of ventilator-induced lung injury (VILI).

    PubMed

    Nieman, Gary F; Satalin, Joshua; Andrews, Penny; Habashi, Nader M; Gatto, Louis A

    2016-12-01

    It was recently shown that acute respiratory distress syndrome (ARDS) mortality has not been reduced in over 15 years and remains ~40 %, even with protective low tidal volume (LVt) ventilation. Thus, there is a critical need to develop novel ventilation strategies that will protect the lung and reduce ARDS mortality. Protti et al. have begun to analyze the impact of mechanical ventilation on lung tissue using engineering methods in normal pigs ventilated for 54 h. They used these methods to assess the impact of a mechanical breath on dynamic and static global lung strain and energy load. Strain is the change in lung volume in response to an applied stress (i.e., Tidal Volume-Vt). This study has yielded a number of exciting new concepts including the following: (1) Individual mechanical breath parameters (e.g., Vt or Plateau Pressure) are not directly correlated with VILI but rather any combination of parameters that subject the lung to excessive dynamic strain and energy/power load will cause VILI; (2) all strain is not equal; dynamic strain resulting in a dynamic energy load (i.e., kinetic energy) is more damaging to lung tissue than static strain and energy load (i.e., potential energy); and (3) a critical consideration is not just the size of the Vt but the size of the lung that is being ventilated by this Vt. This key concept merits attention since our current protective ventilation strategies are fixated on the priority of keeping the Vt low. If the lung is fully inflated, a large Vt is not necessarily injurious. In conclusion, using engineering concepts to analyze the impact of the mechanical breath on the lung is a novel new approach to investigate VILI mechanisms and to help design the optimally protective breath. Data generated using these methods have challenged some of the current dogma surrounding the mechanisms of VILI and of the components in the mechanical breath necessary for lung protection. PMID:27316442

  12. Myocardial Scaffold-based Cardiac Tissue Engineering: Application of Coordinated Mechanical and Electrical Stimulations

    PubMed Central

    Wang, Bo; Wang, Guangjun; To, Filip; Butler, J. Ryan; Claude, Andrew; McLaughlin, Ronald M.; Williams, Lakiesha N.; de Jongh Curry, Amy L.; Liao, Jun

    2013-01-01

    Recently, we have developed an optimal decellularization protocol to generate 3D porcine myocardial scaffolds, which preserved natural extracellular matrix structure, mechanical anisotropy, and vasculature templates, and also showed good cell recellularization and differentiation potential. In this study, a multi-stimulation bioreactor was built to provide coordinated mechanical and electrical stimulations for facilitating stem cell differentiation and cardiac construct development. The acellular myocardial scaffolds were seeded with mesenchymal stem cells (106 cells/ml) by needle injection and subjected to 5-azacytidine treatment (3 μmol/L, 24 h) and various bioreactor conditioning protocols. We found that, after 2-day culture with mechanical (20% strain) and electrical stimulation (5 V, 1 Hz), high cell density and good cell viability were observed in the reseeded scaffold. Immunofluorescence staining demonstrated that the differentiated cells showed cardiomyocyte-like phenotype, by expressing sarcomeric α-actinin, myosin heavy chain, cardiac troponin T, connexin-43, and N-cadherin. Biaxial mechanical testing demonstrated that positive tissue remodeling took place after 2-day bioreactor conditioning (20% strain + 5 V, 1 Hz); passive mechanical properties of the 2-day and 4-day tissue constructs were comparable to the tissue constructs produced by stirring reseeding followed by 2-week static culture, implying the effectiveness and efficiency of the coordinated simulations in promoting tissue remodeling. In short, the synergistic stimulations might be beneficial not only for the quality of cardiac construct development, but also for patients by reducing the waiting time in future clinical scenarios. PMID:23923967

  13. ENGINEERED INTERFACE CHEMISTRY TO IMPROVE THE MECHANICAL PROPERTIES OF CARBON FIBER COMPOSITES CURED BY ELECTRON BEAM

    SciTech Connect

    Vautard, Frederic; Grappe, Hippolyte A.; Ozcan, Soydan

    2014-01-01

    A reactive sizing was designed to achieve high levels of interfacial adhesion and mechanical properties with a carbon fiber-acrylate system cured by electron beam (EB). The sizing was made of a partially cured epoxy sizing with a high density of pendant functional groups (acrylate functionality) able to generate a covalent bonding with the matrix. The interlaminar shear strength was clearly improved from 61 MPa to 81 MPa (+ 33 %) without any post-processing, reaching a similar value to the one obtained with the same system cured by a thermal treatment. Observation of the fracture profiles clearly highlighted a change in the fracture mechanism from a purely adhesive failure to a cohesive failure. Such improvements of the mechanical properties of carbon fiber composites cured by EB, without any post-cure, have not been reported previously to the best of our knowledge. This constitutes a breakthrough for the industrial development of composites EB curing.

  14. Mechanical design engineering. NASA/university advanced design program: Lunar Bulk Material Transport Vehicle

    NASA Technical Reports Server (NTRS)

    Daugherty, Paul; Griner, Stewart; Hendrix, Alan; Makarov, Chris; Martiny, Stephen; Meyhoefer, Douglas Ralph; Platt, Cody Claxton; Sivak, John; Wheeler, Elizabeth Fitch

    1988-01-01

    The design of a Lunar Bulk Material Transport Vehicle (LBMTV) is discussed. Goals set in the project include a payload of 50 cubic feet of lunar soil with a lunar of approximately 800 moon-pounds, a speed of 15 mph, and the ability to handle a grade of 20 percent. Thermal control, an articulated steering mechanism, a dump mechanism, a self-righting mechanism, viable power sources, and a probable control panel are analyzed. The thermal control system involves the use of small strip heaters to heat the housing of electronic equipment in the absence of sufficient solar radiation and multi-layer insulation during periods of intense solar radiation. The entire system uses only 10 W and weighs about 60 pounds, or 10 moon-pounds. The steering mechanism is an articulated steering joint at the center of the vehicle. It utilizes two actuators and yields a turning radius of 10.3 feet. The dump mechanism rotates the bulk material container through an angle of 100 degree using one actuator. The self-righting mechanism consists of two four bar linkages, each of which is powered by the same size actuator as the other linkages. The LBMTV is powered by rechargeable batteries. A running time of at least two hours is attained under a worst case analysis. The weight of the batteries is 100 pounds. A control panel consisting of feedback and control instruments is described. The panel includes all critical information necessary to control the vehicle remotely. The LBMTV is capable of handling many types of cargo. It is able to interface with many types of removable bulk material containers. These containers are made to interface with the three-legged walker, SKITTER. The overall vehicle is about 15 feet in length and has a weight of about 1000 pounds, or 170 lunar pounds.

  15. Mechanical design engineering. NASA/university advanced design program: Lunar Bulk Material Transport Vehicle

    NASA Astrophysics Data System (ADS)

    Daugherty, Paul; Griner, Stewart; Hendrix, Alan; Makarov, Chris; Martiny, Stephen; Meyhoefer, Douglas Ralph; Platt, Cody Claxton; Sivak, John; Wheeler, Elizabeth Fitch

    1988-06-01

    The design of a Lunar Bulk Material Transport Vehicle (LBMTV) is discussed. Goals set in the project include a payload of 50 cubic feet of lunar soil with a lunar of approximately 800 moon-pounds, a speed of 15 mph, and the ability to handle a grade of 20 percent. Thermal control, an articulated steering mechanism, a dump mechanism, a self-righting mechanism, viable power sources, and a probable control panel are analyzed. The thermal control system involves the use of small strip heaters to heat the housing of electronic equipment in the absence of sufficient solar radiation and multi-layer insulation during periods of intense solar radiation. The entire system uses only 10 W and weighs about 60 pounds, or 10 moon-pounds. The steering mechanism is an articulated steering joint at the center of the vehicle. It utilizes two actuators and yields a turning radius of 10.3 feet. The dump mechanism rotates the bulk material container through an angle of 100 degree using one actuator. The self-righting mechanism consists of two four bar linkages, each of which is powered by the same size actuator as the other linkages. The LBMTV is powered by rechargeable batteries. A running time of at least two hours is attained under a worst case analysis. The weight of the batteries is 100 pounds. A control panel consisting of feedback and control instruments is described. The panel includes all critical information necessary to control the vehicle remotely. The LBMTV is capable of handling many types of cargo. It is able to interface with many types of removable bulk material containers. These containers are made to interface with the three-legged walker, SKITTER. The overall vehicle is about 15 feet in length and has a weight of about 1000 pounds, or 170 lunar pounds.

  16. Born–Infeld AdS black holes as heat engines

    NASA Astrophysics Data System (ADS)

    Johnson, Clifford V.

    2016-07-01

    We study the efficiency of heat engines that perform mechanical work via the pdV terms present in the first law in extended gravitational thermodynamics. We use charged black holes as the working substance, for a particular choice of engine cycle. The context is Einstein gravity with negative cosmological constant and a Born–Infeld nonlinear electrodynamics sector. We compare the results for these ‘holographic’ heat engines to previous results obtained for Einstein–Maxwell black holes, and for the case where there is a Gauss–Bonnet sector.

  17. High Precision Mechanical Components for Soft X-ray Beamline: Engineering Goal and Testing Results

    SciTech Connect

    Kaznacheyev, K. V.; Karunakaran, Ch.; Sitnikov, A.; Loken, D.; Warwick, T.; Nagy, M.; Hitchcock, A. P.

    2007-01-19

    As the emittance of SR rings approaches the diffraction limit for soft x-rays, one requires not only excellence in design and performance of the optical elements, but also precision and performance of mechanical components, such as mirror manipulators, monochromator scanners and exit slits. We will present simple but efficient solutions for the mechanical systems of this type, commonly encountered in soft x-ray beamlines. These solutions have been implemented and their performance evaluated with test results from the spectromicroscopy beamline at the Canadian Light Source.

  18. High Precision Mechanical Components for Soft X-ray Beamline: Engineering Goal and Testing Results

    NASA Astrophysics Data System (ADS)

    Kaznacheyev, K. V.; Karunakaran, Ch.; Sitnikov, A.; Loken, D.; Warwick, T.; Nagy, M.; Hitchcock, A. P.

    2007-01-01

    As the emittance of SR rings approaches the diffraction limit for soft x-rays, one requires not only excellence in design and performance of the optical elements, but also precision and performance of mechanical components, such as mirror manipulators, monochromator scanners and exit slits. We will present simple but efficient solutions for the mechanical systems of this type, commonly encountered in soft x-ray beamlines. These solutions have been implemented and their performance evaluated with test results from the spectromicroscopy beamline at the Canadian Light Source.

  19. Bioresorbable scaffolds for bone tissue engineering: optimal design, fabrication, mechanical testing and scale-size effects analysis.

    PubMed

    Coelho, Pedro G; Hollister, Scott J; Flanagan, Colleen L; Fernandes, Paulo R

    2015-03-01

    Bone scaffolds for tissue regeneration require an optimal trade-off between biological and mechanical criteria. Optimal designs may be obtained using topology optimization (homogenization approach) and prototypes produced using additive manufacturing techniques. However, the process from design to manufacture remains a research challenge and will be a requirement of FDA design controls to engineering scaffolds. This work investigates how the design to manufacture chain affects the reproducibility of complex optimized design characteristics in the manufactured product. The design and prototypes are analyzed taking into account the computational assumptions and the final mechanical properties determined through mechanical tests. The scaffold is an assembly of unit-cells, and thus scale size effects on the mechanical response considering finite periodicity are investigated and compared with the predictions from the homogenization method which assumes in the limit infinitely repeated unit cells. Results show that a limited number of unit-cells (3-5 repeated on a side) introduce some scale-effects but the discrepancies are below 10%. Higher discrepancies are found when comparing the experimental data to numerical simulations due to differences between the manufactured and designed scaffold feature shapes and sizes as well as micro-porosities introduced by the manufacturing process. However good regression correlations (R(2) > 0.85) were found between numerical and experimental values, with slopes close to 1 for 2 out of 3 designs. PMID:25640805

  20. Immunotoxicological impact of engineered nanomaterial exposure: mechanisms of immune cell modulation

    PubMed Central

    Wang, Xiaojia; Reece, Shaun P.; Brown, Jared M.

    2013-01-01

    Engineered nanomaterials (ENM) are increasingly being utilized in many consumer products and various medical applications thereby leading to the potentiality of increased human exposures. Assessment of the adverse effects on the immune system is an important component for evaluating the overall health and safety of ENM. Tasked with eliminating pathogens and removing cancerous cells, the immune system is constantly functioning to maintain homeostasis. Small modifications to the immune system which may occur following ENM exposure, could lead to impaired protection or an inappropriate immune response resulting in autoimmunity and damage to the host. This review seeks to survey and evaluate the current literature to better understand the impact of ENM exposure on cells critical to the innate and adaptive immune systems. PMID:23256453

  1. The physical and mechanical properties of laterite gravels from southeastern Nigeria relative to their engineering performance

    NASA Astrophysics Data System (ADS)

    Okagbue, C. O.

    Laterite gravels are used extensively as aggregates for highway construction, concrete making and fills in SE Nigeria. This paper presents results of laboratory investigations carried out to evaluate the physical and mechanical properties of these gravels. High mechanical strength, as measured by aggregate crushing (AC), and Los Angeles abrasion (LAA) values were found to be significant factors controlling the performance. Results indicate that significant correlations exist between these and specific gravity, water absorption and angularity of the gravels. No clear distinction in physical and mechanical properties could be found between the laterite gravels formed over sandstones and shales, indicating perhaps that effects of parent rock on the physical and mechanical nature of laterite gravels is of secondary importance. It is proposed that laterite gravels with AC and LAA values in the range of 30-40% and 34-45%, respectively and 10% fines value of between 8 and 4 tonnes be used only for medium and light trafficked roads. Those with AC and LAA values of less than 30% and 34%, respectively and 10% fines value of greater than 8 tonnes can be used for heavily trafficked roads, provided that acceptable gradation, plasticity limits (on the fines) and other construction specifications are met.

  2. Proceedings of the eighth international conference on offshore mechanics and Arctic engineering. 1989

    SciTech Connect

    Sinha, N.K. ); Sodhi, D.S. ); Chung, J.S. )

    1989-01-01

    This book contains papers presented at a conference on arctic and polar technology. The topics covered are: Ice properties; Ice mechanics and dynamics; Spray ice technology; Ice forces; Ice accretion; Standards on arctic developments; The Barents Sea; and Arctic structures and drilling.

  3. General Mechanical Repair 2. Minor Automotive Maintenance, Small Engine [Repair, and] Welding. Curriculum Guide.

    ERIC Educational Resources Information Center

    Hamlin, Larry

    This curriculum guide provides materials for teachers to use in developing a 1-year course in general mechanical repair as part of the trade and industrial education curriculum. The guide contains the following: (1) essential elements common to all trade and industrial courses; (2) an instructional delivery outline (teaching sequence) for the…

  4. Stirling engines

    SciTech Connect

    Walker, G.

    1980-01-01

    Stirling engines exist in a bewildering array of mechanical arrangements. This book attempts to describe and classify the systems in a rational way, to explain the intricacies of the cycle, and to present a large amount of detailed information related to Stirling engines such as design, heat exchangers, working fluids, operation and performance, control equipment, recently developed engines, and current and proposed uses. (LCL)

  5. Achievements of engineering students on a fluid mechanics course in relation to the use of illustrative interactive simulations

    NASA Astrophysics Data System (ADS)

    Romero, Carlos; Martínez, Elvira

    2013-07-01

    Among other skills, a capacity for abstraction and good spatial awareness are needed to succeed in physics courses. According to the prevailing low percentages of passed students on these courses, a great proportion of those students are likely to lack these skills. Our working hypothesis is that simulations could help engineering students visualize physical phenomena and thereby gain a better understanding of physical theoretical concepts and achieve higher grades. Two groups of students (n1 = 40 and n2 = 43) took the same fluid mechanics course at an engineering school. Both groups took the same end-of-course examination, but only group 1 was simulation-taught. For that purpose, 15 original simulations were created with GeoGebra software. Simulation-taught students completed a questionnaire on the interest of using simulations to teach fluid mechanics. Simulations designed in this work covered all the concepts taught on the course and overcame criticisms made on previous simulations also created to teach fluid mechanics. At the examination, the average grade and the percentage of passed students were higher in group 1 than in group 2. When surveyed, group 1 students declared that they enjoyed interacting with the simulations and considered them to be a good complement to the theoretical explanations because simulations helped them revise previously explained concepts. Simulations assisted students with difficulties to visualize and understand physical theoretical concepts but still students performed poorly on the examination. Additional strategies need to be adopted in order to help students develop the skills required to succeed in physics courses.

  6. Image-based quantification of fiber alignment within electrospun tissue engineering scaffolds is related to mechanical anisotropy.

    PubMed

    Fee, Timothy; Downs, Crawford; Eberhardt, Alan; Zhou, Yong; Berry, Joel

    2016-07-01

    It is well documented that electrospun tissue engineering scaffolds can be fabricated with variable degrees of fiber alignment to produce scaffolds with anisotropic mechanical properties. Several attempts have been made to quantify the degree of fiber alignment within an electrospun scaffold using image-based methods. However, these methods are limited by the inability to produce a quantitative measure of alignment that can be used to make comparisons across publications. Therefore, we have developed a new approach to quantifying the alignment present within a scaffold from scanning electron microscopic (SEM) images. The alignment is determined by using the Sobel approximation of the image gradient to determine the distribution of gradient angles with an image. This data was fit to a Von Mises distribution to find the dispersion parameter κ, which was used as a quantitative measure of fiber alignment. We fabricated four groups of electrospun polycaprolactone (PCL) + Gelatin scaffolds with alignments ranging from κ = 1.9 (aligned) to κ = 0.25 (random) and tested our alignment quantification method on these scaffolds. It was found that our alignment quantification method could distinguish between scaffolds of different alignments more accurately than two other published methods. Additionally, the alignment parameter κ was found to be a good predictor the mechanical anisotropy of our electrospun scaffolds. The ability to quantify fiber alignment within and make direct comparisons of scaffold fiber alignment across publications can reduce ambiguity between published results where cells are cultured on "highly aligned" fibrous scaffolds. This could have important implications for characterizing mechanics and cellular behavior on aligned tissue engineering scaffolds. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1680-1686, 2016. PMID:26939754

  7. The scanning mechanism for ROSETTA/MIDAS: from an engineering model to the flight model

    NASA Astrophysics Data System (ADS)

    Le Letty, R.; Barillot, F.; Lhermet, N.; Claeyssen, F.; Yorck, M.; Gavira Izquierdo, J.; Arends, H.

    2001-09-01

    The MIDAS (Micro Imaging Dust Analysis System) instrument jointly developed by IWF Graz (AT) and the Solar Space Division of ESA/ESTEC (NL) will flow on ROSETTA and will analyse the dust of the 46P/Wirtanen comet using an Atomic Force Microscope (AFM). A piezoelectric XYZ stage, used to scan the sample in 3 axis, is part of the instrument and has been fully designed and qualified under the ESA/ESTEC contract no13090/98/NL/MV. Two qualification models (EQM/QM) and two flight models (FM/FSM) have been integrated and fully tested within 18 months. The basic principle of the stage has been described in a previous paper. The XY stage includes a latch mechanism based on two Shape Memory actuators. This paper focuses on the lessons learned during the qualification campaign, especially on the testing activities and on the latch mechanism. The XYZ stage has followed a full qualification campaign including Thermal Vacuum cycles, Random Vibrations tests and lifetime tests. The latch mechanism has been designed and tested with the following features: easiness of locking and refurbishment operations, compatibility with the parallel two degrees of freedom mechanism, low shock device. It has been tested more than 20 times, including 4 tests in the worst case conditions (eg the most demanding power case at -20°C) and 2 times after a vibration test. The results and the parameters influencing the reproducibility are discussed. The functional performances have been assessed using a dedicated test bench. Comments are made on the measurements techniques used to get results independent from the drift effect displayed by the piezo components. The calibration work (static and gain of the position sensors) have played an important role during the testing activities. Several parameters (temperature, piezo drift effect and external forces acting on the stage and coming from the coarse approach mechanism) affects the static position. Because of the limited stroke range of reading of the

  8. The Evaluation of the Effectiveness of ESP Courses in Enhancing Technical Translation Proficiency: A Case Study of ESP Course for Mechanical Engineering Students

    ERIC Educational Resources Information Center

    Hatam, Amir Hussein; Shafiei, Shilan

    2012-01-01

    The purpose of the present study was twofold. Firstly, it tried to investigate the relationship between the technical English proficiency of the students of Mechanical Engineering in the universities of Iran and their technical translation proficiency in translating technical texts of Mechanics. Secondly, it attempted to evaluate the effectiveness…

  9. Mechanical properties of natural chitosan/hydroxyapatite/magnetite nanocomposites for tissue engineering applications.

    PubMed

    Heidari, Fatemeh; Razavi, Mehdi; E Bahrololoom, Mohammad; Bazargan-Lari, Reza; Vashaee, Daryoosh; Kotturi, Hari; Tayebi, Lobat

    2016-08-01

    Chitosan (CS), hydroxyapatite (HA), and magnetite (Fe3O4) have been broadly employed for bone treatment applications. Having a hybrid biomaterial composed of the aforementioned constituents not only accumulates the useful characteristics of each component, but also provides outstanding composite properties. In the present research, mechanical properties of pure CS, CS/HA, CS/HA/magnetite, and CS/magnetite were evaluated by the measurements of bending strength, elastic modulus, compressive strength and hardness values. Moreover, the morphology of the bending fracture surfaces were characterized using a scanning electron microscope (SEM) and an image analyzer. Studies were also conducted to examine the biological response of the human Mesenchymal Stem Cells (hMSCs) on different composites. We conclude that, although all of these composites possess in-vitro biocompatibility, adding hydroxyapatite and magnetite to the chitosan matrix can noticeably enhance the mechanical properties of the pure chitosan. PMID:27157760

  10. Lipid Exchange Envelope Penetration (LEEP) of Nanoparticles for Plant Engineering: A Universal Localization Mechanism.

    PubMed

    Wong, Min Hao; Misra, Rahul P; Giraldo, Juan P; Kwak, Seon-Yeong; Son, Youngwoo; Landry, Markita P; Swan, James W; Blankschtein, Daniel; Strano, Michael S

    2016-02-10

    Nanoparticles offer clear advantages for both passive and active penetration into biologically important membranes. However, the uptake and localization mechanism of nanoparticles within living plants, plant cells, and organelles has yet to be elucidated.1 Here, we examine the subcellular uptake and kinetic trapping of a wide range of nanoparticles for the first time, using the plant chloroplast as a model system, but validated in vivo in living plants. Confocal visible and near-infrared fluorescent microscopy and single particle tracking of gold-cysteine-AF405 (GNP-Cys-AF405), streptavidin-quantum dot (SA-QD), dextran and poly(acrylic acid) nanoceria, and various polymer-wrapped single-walled carbon nanotubes (SWCNTs), including lipid-PEG-SWCNT, chitosan-SWCNT and 30-base (dAdT) sequence of ssDNA (AT)15 wrapped SWCNTs (hereafter referred to as ss(AT)15-SWCNT), are used to demonstrate that particle size and the magnitude, but not the sign, of the zeta potential are key in determining whether a particle is spontaneously and kinetically trapped within the organelle, despite the negative zeta potential of the envelope. We develop a mathematical model of this lipid exchange envelope and penetration (LEEP) mechanism, which agrees well with observations of this size and zeta potential dependence. The theory predicts a critical particle size below which the mechanism fails at all zeta potentials, explaining why nanoparticles are critical for this process. LEEP constitutes a powerful particulate transport and localization mechanism for nanoparticles within the plant system. PMID:26760228

  11. Proceedings of the fifth international offshore mechanics and Arctic engineering (OMAE) symposium. Volume 3

    SciTech Connect

    Chung, J.S.; Yoshida, K.; Sparks, C.P.; Tsahalis, D.T.

    1986-01-01

    This book presents the paper given at a symposium on offshore platforms. Topics considered at the symposium included tension leg platforms, tether damage, mechanical vibrations, seismic effects, guyed towers, nonlinear characteristics, wave forces, jack-up drilling units, design, impact strength, barges, hoists, remotely-controlled underwater vehicles, buckle initiation in damaged subsea pipelines, flexible marine risers, offshore cables, hydrodynamics, fatigue properties of mooring chains, underwater inspection systems, offshore accidents, quality assurance, safety, deep water gravity platforms, reinforced concrete, foundations, and leak testing.

  12. Mechanisms and Determinants of RNA Turnover: Plant IRESs and Polycistrons for Metabolic Engineering

    SciTech Connect

    Richard B. Meagher

    2002-08-01

    There is a strong need for tools that allow multiple transgenes to be expressed in genetically engineered plants. For the last 30 years it has been believed that nearly all eukaryotic mRNAs were monocistronic, with ribosomes entering at the 5' end and scanning through the 5'UTR to the first AUG codon. It is now clear that perhaps 3% of vertebrate and yeast mRNAs utilize IRESs (Internal Ribosome Entry Sites) within their 5'UTRs to promote the internal entry of ribosomes to mRNAs and subsequent translation of protein without scanning. The working hypothesis behind this proposal is that IRES sequences function in plants and can be used to engineer the efficient co-expression of multiple proteins from polycistronic transcripts. Our goal was to translate multiple proteins from single polycistroic mRNAs. We cloned four IRESs from the following sources: CrTMV (plant virus), EMCV (human encephalomyocarditis virus), eIF4G (human), and c-myc (human). All four IRES were cloned into a specially designed test vector with the strong constitutive ACT2 actin regulatory sequences and flanked by multicloning sites for two reporter genes. These four IRESs were tested in three different test systems with strong paired reporter activities: two fluorescent proteins, two mercury resistance enzymes, and two biosynthetic enzymes making thiolpeptides. All of the four IRES constructs with the fluorescent protein reporter genes were tested for transient expression after particle gun bombardment of tobacco BY2 cells. Three of the IRESs gave reasonable activity (10%-40%) for the second cistron fluorescent reporter (DsRFP) relative to the first cistron reporter (GFP). As a control, translational blocking sequence placed at the 5' end of duplicate constructs had little effect on activity from the second cistron, but blocked the first cistron. These initial positive data lead us to examine the four IRES constructs with three pairs of reporters in hundreds of transgenic Arabidopsis plants. All

  13. Biochemical, mechanical, and spectroscopic analyses of genetically engineered flax fibers producing bioplastic (poly-beta-hydroxybutyrate).

    PubMed

    Wróbel-Kwiatkowska, Magdalena; Skórkowska-Telichowska, Katarzyna; Dymińska, Lucyna; Maczka, Mirosław; Hanuza, Jerzy; Szopa, Jan

    2009-01-01

    The interest in biofibers has grown in recent years due to their expanding range of applications in fields as diverse as biomedical science and the automotive industry. Their low production costs, biodegradability, physical properties, and perceived eco-friendliness allow for their extensive use as composite components, a role in which they could replace petroleum-based synthetic polymers. We performed biochemical, mechanical, and structural analyses of flax stems and fibers derived from field-grown transgenic flax enriched with PHB (poly-beta-hydroxybutyrate). The analyses of the plant stems revealed an increase in the cellulose content and a decrease in the lignin and pectin contents relative to the control plants. However, the contents of the fibers' major components (cellulose, lignin, pectin) remain unchanged. An FT-IR study confirmed the results of the biochemical analyses of the flax fibers. However, the arrangement of the cellulose polymer in the transgenic fibers differed from that in the control, and a significant increase in the number of hydrogen bonds was detected. The mechanical properties of the transgenic flax stems were significantly improved, reflecting the cellulose content increase. However, the mechanical properties of the fibers did not change in comparison with the control, with the exception of the fibers from transgenic line M13. The generated transgenic flax plants, which produce both components of the flax/PHB composites (i.e., fibers and thermoplastic matrix in the same plant organ) are a source of an attractive and ecologically safe material for industry and medicine. PMID:19572280

  14. The crucial role of mechanical heterogeneity in regulating follicle development and ovulation with engineered ovarian microtissue

    PubMed Central

    Choi, Jung Kyu; Agarwal, Pranay; Huang, Haishui; Zhao, Shuting; He, Xiaoming

    2014-01-01

    Contemporary systems for in vitro culture of ovarian follicles do not recapitulate the mechanical heterogeneity in mammalian ovary. Here we report microfluidic generation of biomimetic ovarian microtissue for miniaturized three-dimensional (3D) culture of early secondary preantral follicles by using alginate (harder) and collagen (softer) to fabricate the ovarian cortical and medullary tissues, respectively. This biomimetic configuration greatly facilitates follicle development to antral stage. Moreover, it enables in vitro ovulation of cumulus-oocyte complex (COC) from the antral follicles in the absence of luteinizing hormone (LH) and epidermal growth factor (EGF) that are well accepted to be responsible for ovulation in contemporary literature. These data reveal the crucial role of mechanical heterogeneity in the mammalian ovary in regulating follicle development and ovulation. The biomimetic ovarian microtissue and the microfluidic technology developed in this study are valuable for improving in vitro culture of follicles to preserve fertility and for understanding the mechanism of follicle development and ovulation to facilitate the search of cures to infertility due to ovarian disorders. PMID:24702961

  15. Parametric finite element analysis of physical stimuli resulting from mechanical stimulation of tissue engineered cartilage.

    PubMed

    Babalola, Omotunde M; Bonassar, Lawrence J

    2009-06-01

    While mechanical stimulation of cells seeded within scaffolds is widely thought to be beneficial, the amount of benefit observed is highly variable between experimental systems. Although studies have investigated specific experimental loading protocols thought to be advantageous for cartilage growth, less is known about the physical stimuli (e.g., pressures, velocities, and local strains) cells experience during these experiments. This study used results of a literature survey, which looked for patterns in the efficacy of mechanical stimulation of chondrocyte seeded scaffolds, to inform the modeling of spatial patterns of physical stimuli present in mechanically stimulated constructs. The literature survey revealed a large variation in conditions used in mechanical loading studies, with a peak to peak strain of 10% (i.e., the maximum amount of deformation experienced by the scaffold) at 1 Hz on agarose scaffolds being the most frequently studied parameters and scaffold. This loading frequency was then used as the basis for simulation in the finite element analyses. 2D axisymmetric finite element models of 2x4 mm2 scaffolds with 360 modulus/permeability combinations were constructed using COMSOL MULTIPHYSICS software. A time dependent coupled pore pressure/effective stress analysis was used to model fluid/solid interactions in the scaffolds upon loading. Loading was simulated using an impermeable frictionless loader on the top boundary with fluid and solid displacement confined to the radial axis. As expected, all scaffold materials exhibited classic poro-elastic behavior having pressurized cores with low fluid flow and edges with high radial fluid velocities. Under the simulation parameters of this study, PEG scaffolds had the highest pressure and radial fluid velocity but also the lowest shear stress and radial strain. Chitosan and KLD-12 simulated scaffold materials had the lowest radial strains and fluid velocities, with collagen scaffolds having the lowest

  16. Simultaneous utilization of glucose and xylose via novel mechanisms in engineered Escherichia coli.

    PubMed

    Kim, Suk Min; Choi, Bae Young; Ryu, Young Shin; Jung, Sung Hun; Park, Jung Min; Kim, Goo-Hee; Lee, Sung Kuk

    2015-07-01

    After glucose, xylose is the most abundant sugar in lignocellulosic carbon sources. However, wild-type Escherichia coli is unable to simultaneously utilize both sugars due to carbon catabolite repression (CCR). In this paper, we describe GX50, an engineered strain capable of utilizing glucose and xylose simultaneously. This strain was obtained by evolving a mutant from which araC has been deleted, and in which genes required for pentose metabolism are constitutively expressed. The strain acquired four additional mutations during adaptive evolution, including intergenic mutations in the 5'-flanking region of xylA and pyrE, and missense mutations in araE (S91I) and ybjG (D99G). In contrast to wild type E. coli, GX50 rapidly converts xylose to xylitol even if glucose is available. Notably, the strain grows well when cultured on glucose, unlike some well-known CCR-insensitive mutants defective in the glucose phosphotransferase system. Our work will advance efforts to design a metabolically efficient platform strain for potential use in producing chemicals from lignocellulose. PMID:26045332

  17. Design, fabrication and operation of the mechanical systems for the Neutral Beam Engineering Test Facility

    SciTech Connect

    Paterson, J.A.; Biagi, L.A.; Fong, M.; Koehler, G.W.; Low, W.; Purgalis, P.; Wells, R.P.

    1983-12-01

    The Neutral Beam Engineering Test Facility (NBETF) at Lawrence Berkeley Laboratory (LBL) is a National Test Facility used to develop long pulse Neutral Beam Sources. The Facility will test sources up to 120 keV, 50 A, with 30 s beam-on times with a 10% duty factor. For this application, an actively cooled beam dump is required and one has been constructed capable of dissipating a wide range of power density profiles. The flexibility of the design is achieved by utilizing a standard modular panel design which is incorporated into a moveable support structure comprised of eight separately controllable manipulator assemblies. A unique neutralizer design has been installed into the NBETF beamline. This is a gun-drilled moveable brazed assembly which provides continuous armoring of the beamline near the source. The unit penetrates the source mounting valve during operation and retracts to permit the valve to close as needed. The beamline is also equpped with many beam scraper plates of differing detail design and dissipation capabilities.

  18. Orthogonal site-specific protein modification by engineering reversible thiol protection mechanisms

    PubMed Central

    Smith, J. Jefferson; Conrad, David W.; Cuneo, Matthew J.; Hellinga, Homme W.

    2005-01-01

    Covalent modification is an important strategy for introducing new functions into proteins. As engineered proteins become more sophisticated, it is often desirable to introduce multiple, modifications involving several different functionalities in a site-specific manner. Such orthogonal labeling schemes require independent labeling of differentially reactive nucleophilic amino acid side chains. We have developed two protein-mediated protection schemes that permit independent labeling of multiple thiols. These schemes exploit metal coordination or disulfide bond formation to reversibly protect cysteines in a Cys2His2 zinc finger domain. We constructed a variety of N- and C-terminal fusions of these domains with maltose-binding protein, which were labeled with two or three different fluorophores. Multiple modifications were made by reacting an unprotected cysteine in MBP first, deprotecting the zinc finger, and then reacting the zinc finger cysteines. The fusion proteins were orthogonally labeled with two different fluorophores, which exhibited intramolecular fluorescene resonance energy transfer (FRET). These conjugates showed up to a threefold ratiometric change in emission intensities in response to maltose binding. We also demonstrated that the metal- and redox-mediated protection methods can be combined to produce triple independent modifications, and prepared a protein labeled with three different fluorophores that exhibited a FRET relay. Finally, labeled glucose-binding protein was covalently patterned on glass slides using thiol-mediated immobilization chemistries. Together, these experiments demonstrated that reversible thiol protection schemes provide a rapid, straightforward method for producing multiple, site-specific modifications. PMID:15576565

  19. Protein engineering in the alpha-amylase family: catalytic mechanism, substrate specificity, and stability.

    PubMed

    Svensson, B

    1994-05-01

    Most starch hydrolases and related enzymes belong to the alpha-amylase family which contains a characteristic catalytic (beta/alpha)8-barrel domain. Currently known primary structures that have sequence similarities represent 18 different specificities, including starch branching enzyme. Crystal structures have been reported in three of these enzyme classes: the alpha-amylases, the cyclodextrin glucanotransferases, and the oligo-1,6-glucosidases. Throughout the alpha-amylase family, only eight amino acid residues are invariant, seven at the active site and a glycine in a short turn. However, comparison of three-dimensional models with a multiple sequence alignment suggests that the diversity in specificity arises by variation in substrate binding at the beta-->alpha loops. Designed mutations thus have enhanced transferase activity and altered the oligosaccharide product patterns of alpha-amylases, changed the distribution of alpha-, beta- and gamma-cyclodextrin production by cyclodextrin glucanotransferases, and shifted the relative alpha-1,4:alpha-1,6 dual-bond specificity of neopullulanase. Barley alpha-amylase isozyme hybrids and Bacillus alpha-amylases demonstrate the impact of a small domain B protruding from the (beta/alpha)8-scaffold on the function and stability. Prospects for rational engineering in this family include important members of plant origin, such as alpha-amylase, starch branching and debranching enzymes, and amylomaltase. PMID:8018865

  20. The effect of curricular activities on learner autonomy: the perspective of undergraduate mechanical engineering students

    NASA Astrophysics Data System (ADS)

    Duarte, M.; Leite, C.; Mouraz, A.

    2016-01-01

    This study researches how first-year engineering students perceived the influence of curricular activities on their own learning autonomy, measured with an adaptation of the Personal Responsibility Orientation to Self-direction in Learning Scale (PRO-SDLS). Participants were questioned to assess the influence of the teacher's role. The results indicate that learners' characteristics (motivation and self-efficacy) contribute more to learner autonomy (LA) than the teaching-learning transaction (control and initiative), as in the original PRO-SDLS validation. The most autonomous learners presented higher values in all LA components and dimensions, but the differences were greater in motivation and initiative. The participants with higher LA were not as dependent on the teacher, regarding assessment, the completion of classroom tasks and deadlines. Regardless of the degree of autonomy in learning, all participants viewed teachers as the main source of information. Therefore, LA plays an important role in teaching activities planning. Suggestions for adjustments and more flexible learning scenarios are formulated.

  1. Mechanical coordination in motor ensembles revealed using engineered artificial myosin filaments.

    PubMed

    Hariadi, R F; Sommese, R F; Adhikari, A S; Taylor, R E; Sutton, S; Spudich, J A; Sivaramakrishnan, S

    2015-08-01

    The sarcomere of muscle is composed of tens of thousands of myosin motors that self-assemble into thick filaments and interact with surrounding actin-based thin filaments in a dense, near-crystalline hexagonal lattice. Together, these actin-myosin interactions enable large-scale movement and force generation, two primary attributes of muscle. Research on isolated fibres has provided considerable insight into the collective properties of muscle, but how actin-myosin interactions are coordinated in an ensemble remains poorly understood. Here, we show that artificial myosin filaments, engineered using a DNA nanotube scaffold, provide precise control over motor number, type and spacing. Using both dimeric myosin V- and myosin VI-labelled nanotubes, we find that neither myosin density nor spacing has a significant effect on the gliding speed of actin filaments. This observation supports a simple model of myosin ensembles as energy reservoirs that buffer individual stochastic events to bring about smooth, continuous motion. Furthermore, gliding speed increases with cross-bridge compliance, but is limited by Brownian effects. As a first step to reconstituting muscle motility, we demonstrate human β-cardiac myosin-driven gliding of actin filaments on DNA nanotubes. PMID:26149240

  2. Dynamic study for performance improvements of a thermo-mechanically bistable heat engine

    NASA Astrophysics Data System (ADS)

    Boughaleb, J.; Arnaud, A.; Monfray, S.; Cottinet, P. J.; Quenard, S.; Pitone, G.; Boeuf, F.; Guyomar, D.; Skotnicki, T.

    2015-12-01

    This paper focuses on a thermal study of a thermal energy harvester based on the coupling of a bimetallic strip heat engine with a piezoelectric membrane for wasted heat scavenging. Such a harvester is dedicated to power autonomous systems such as wireless sensor nodes. For a better understanding of the working principle of the system, it is compulsory to have a good understanding of the thermal specificities and phenomenon taking place inside the harvester. Attention is consequently focused on the thermal modeling of the harvester in static mode using the equivalence between the electrical and thermal quantities. This first modeling step allowed the improvement of the thermal properties inside the system by increasing the thermal gradient across it. However, the bimetal being the active part of the system has not been taken into account in this model and shadow zones persisted regarding the bimetal operation windows as a function of its snapping temperatures and hysteresis. To overcome this, a dynamic model is proposed in this paper taking into account the bimetal as a switched capacitance alternatively in contact with the hot source and the cold surface. This last model completed the static one by predicting the bimetal's operation windows in function of its intrinsic properties and the operation range evolution in function of the snapping temperature first and then in function of the bimetal thermal hysteresis. Moreover, experimental measurements enable to validate the proposed model and to point out the most powerful bimetals for scavenging higher amounts of power.

  3. Characterization and mechanical performance study of silk/PVA cryogels: towards nucleus pulposus tissue engineering.

    PubMed

    Neo, Puay Yong; Shi, Pujiang; Goh, James Cho-Hong; Toh, Siew Lok

    2014-12-01

    Poly (vinyl) alcohol (PVA) cryogels are reported in the literature for application in nucleus pulposus (NP) replacement strategies. However, these studies are mainly limited to acellular approaches-in part due to the high hydrophilicity of PVA gels that renders cellular adhesion difficult. Silk is a versatile biomaterial with excellent biocompatibility. We hypothesize that the incorporation of silk with PVA will (i) improve the cell-hosting abilities of PVA cryogels and (ii) allow better tailoring of physical properties of the composite cryogels for an NP tissue engineering purpose. 5% (wt/vol) PVA is blended with 5% silk fibroin (wt/vol) to investigate the effect of silk : PVA ratios on the cryogels' physical properties. Results show that the addition of silk results in composite cryogels that are able to swell to more than 10 times its original dry weight and rehydrate to at least 70% of its original wet weight. Adding at least 20% silk significantly improves surface hydrophobicity and is correlated with an improvement in cell-hosting abilities. Cell-seeded cryogels also display an increment in compressive modulus and hoop stress values. In all, adding silk to PVA creates cryogels that can be potentially used as NP replacements. PMID:25329452

  4. Mechanical coordination in motor ensembles revealed using engineered artificial myosin filaments

    NASA Astrophysics Data System (ADS)

    Hariadi, R. F.; Sommese, R. F.; Adhikari, A. S.; Taylor, R. E.; Sutton, S.; Spudich, J. A.; Sivaramakrishnan, S.

    2015-08-01

    The sarcomere of muscle is composed of tens of thousands of myosin motors that self-assemble into thick filaments and interact with surrounding actin-based thin filaments in a dense, near-crystalline hexagonal lattice. Together, these actin-myosin interactions enable large-scale movement and force generation, two primary attributes of muscle. Research on isolated fibres has provided considerable insight into the collective properties of muscle, but how actin-myosin interactions are coordinated in an ensemble remains poorly understood. Here, we show that artificial myosin filaments, engineered using a DNA nanotube scaffold, provide precise control over motor number, type and spacing. Using both dimeric myosin V- and myosin VI-labelled nanotubes, we find that neither myosin density nor spacing has a significant effect on the gliding speed of actin filaments. This observation supports a simple model of myosin ensembles as energy reservoirs that buffer individual stochastic events to bring about smooth, continuous motion. Furthermore, gliding speed increases with cross-bridge compliance, but is limited by Brownian effects. As a first step to reconstituting muscle motility, we demonstrate human β-cardiac myosin-driven gliding of actin filaments on DNA nanotubes.

  5. Abelian Hidden Sectors at a GeV

    SciTech Connect

    Morrissey, David E.; Poland, David; Zurek, Kathryn; /Fermilab /Michigan U.

    2009-04-16

    We discuss mechanisms for naturally generating GeV-scale hidden sectors in the context of weak-scale supersymmetry. Such low mass scales can arise when hidden sectors are more weakly coupled to supersymmetry breaking than the visible sector, as happens when supersymmetry breaking is communicated to the visible sector by gauge interactions under which the hidden sector is uncharged, or if the hidden sector is sequestered from gravity-mediated supersymmetry breaking. We study these mechanisms in detail in the context of gauge and gaugino mediation, and present specific models of Abelian GeV-scale hidden sectors. In particular, we discuss kinetic mixing of a U(1){sub x} gauge force with hypercharge, singlets or bi-fundamentals which couple to both sectors, and additional loop effects. Finally, we investigate the possible relevance of such sectors for dark matter phenomenology, as well as for low- and high-energy collider searches.

  6. A Model-Based Product Evaluation Protocol for Comparison of Safety-Engineered Protection Mechanisms of Winged Blood Collection Needles.

    PubMed

    Haupt, C; Spaeth, J; Ahne, T; Goebel, U; Steinmann, D

    2016-05-01

    OBJECTIVE To evaluate differences in product characteristics and user preferences of safety-engineered protection mechanisms of winged blood collection needles. DESIGN Randomized model-based simulation study. SETTING University medical center. PARTICIPANTS A total of 33 third-year medical students. METHODS Venipuncture was performed using winged blood collection needles with 4 different safety mechanisms: (a) Venofix Safety, (b) BD Vacutainer Push Button, (c) Safety-Multifly, and (d) Surshield Surflo. Each needle type was used in 3 consecutive tries: there was an uninstructed first handling, then instructions were given according to the operating manual; subsequently, a first trial and second trial were conducted. Study end points included successful activation, activation time, single-handed activation, correct activation, possible risk of needlestick injury, possibility of deactivation, and preferred safety mechanism. RESULTS The overall successful activation rate during the second trial was equal for all 4 devices (94%-100%). Median activation time was (a) 7 s, (b) 2 s, (c) 9 s, and (d) 7 s. Single-handed activation during the second trial was (a) 18%, (b) 82%, (c) 15%, and (d) 45%. Correct activation during the second trial was (a) 3%, (b) 64%, (c) 15%, and (d) 39%. Possible risk of needlestick injury during the second trial was highest with (d). Possibility of deactivation was (a) 0%, (b) 12%, (c) 9%, and (d) 18%. Individual preferences for each system were (a) 11, (b) 17, (c) 5, and (d) 0. The main reason for preference was the comprehensive safety mechanism. CONCLUSION Significant differences exist between safety mechanisms of winged blood collection needles. Infect Control Hosp Epidemiol 2016;37:505-511. PMID:26868306

  7. Hydroxyapatite-TiO(2)-based nanocomposites synthesized in supercritical CO(2) for bone tissue engineering: physical and mechanical properties.

    PubMed

    Salarian, Mehrnaz; Xu, William Z; Wang, Zhiqiang; Sham, Tsun-Kong; Charpentier, Paul A

    2014-10-01

    Calcium phosphate-based nanocomposites offer a unique solution toward producing scaffolds for orthopedic and dental implants. However, despite attractive bioactivity and biocompatibility, hydroxyapatite (HAp) has been limited in heavy load-bearing applications due to its intrinsically low mechanical strength. In this work, to improve the mechanical properties of HAp, we grew HAp nanoplates from the surface of one-dimensional titania nanorod structures by combining a coprecipitation and sol-gel methodology using supercritical fluid processing with carbon dioxide (scCO2). The effects of metal alkoxide concentration (1.1-1.5 mol/L), reaction temperature (60-80 °C), and pressure (6000-8000 psi) on the morphology, crystallinity, and surface area of the resulting nanostructured composites were examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and Brunauer-Emmet-Teller (BET) method. Chemical composition of the products was characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption near-edge structure (XANES) analyses. HAp nanoplates and HAp-TiO2 nanocomposites were homogeneously mixed within poly(ε-caprolactone) (PCL) to develop scaffolds with enhanced physical and mechanical properties for bone regeneration. Mechanical behavior analysis demonstrated that the Young's and flexural moduli of the PCL/HAp-TiO2 composites were substantially higher than the PCL/HAp composites. Therefore, this new synthesis methodology in scCO2 holds promise for bone tissue engineering with improved mechanical properties. PMID:25184699

  8. Cell-laden photocrosslinked GelMA-DexMA copolymer hydrogels with tunable mechanical properties for tissue engineering.

    PubMed

    Wang, Hang; Zhou, Lei; Liao, Jingwen; Tan, Ying; Ouyang, Kongyou; Ning, Chenyun; Ni, Guoxin; Tan, Guoxin

    2014-09-01

    To effectively repair or replace damaged tissues, it is necessary to design three dimensional (3D) extracellular matrix (ECM) mimicking scaffolds with tunable biomechanical properties close to the desired tissue application. In the present work, gelatin methacrylate (GelMA) and dextran glycidyl methacrylate (DexMA) with tunable mechanical and biological properties were utilized to prepared novel bicomponent polymeric hydrogels by cross-linking polymerization using photoinitiation. We controlled the degree of substitution (DS) of glycidyl methacrylate in DexMA so that they could obtain relevant mechanical properties. The results indicated that copolymer hydrogels demonstrated a lower swelling ratio and higher compressive modulus as compared to the GelMA. Moreover, all of the hydrogels exhibited a honeycomb-like architecture, the pore sizes decreased as DS increased, and NIH-3T3 fibroblasts encapsulated in these hydrogels all exhibited excellent viability. These characteristics suggest a class of photocrosslinkable, tunable mechanically copolymer hydrogels that may find potential application in tissue engineering and regenerative medicine applications. PMID:25008369

  9. A novel antibody engineering strategy for making monovalent bispecific heterodimeric IgG antibodies by electrostatic steering mechanism.

    PubMed

    Liu, Zhi; Leng, Esther C; Gunasekaran, Kannan; Pentony, Martin; Shen, Min; Howard, Monique; Stoops, Janelle; Manchulenko, Kathy; Razinkov, Vladimir; Liu, Hua; Fanslow, William; Hu, Zhonghua; Sun, Nancy; Hasegawa, Haruki; Clark, Rutilio; Foltz, Ian N; Yan, Wei

    2015-03-20

    Producing pure and well behaved bispecific antibodies (bsAbs) on a large scale for preclinical and clinical testing is a challenging task. Here, we describe a new strategy for making monovalent bispecific heterodimeric IgG antibodies in mammalian cells. We applied an electrostatic steering mechanism to engineer antibody light chain-heavy chain (LC-HC) interface residues in such a way that each LC strongly favors its cognate HC when two different HCs and two different LCs are co-expressed in the same cell to assemble a functional bispecific antibody. We produced heterodimeric IgGs from transiently and stably transfected mammalian cells. The engineered heterodimeric IgG molecules maintain the overall IgG structure with correct LC-HC pairings, bind to two different antigens with comparable affinity when compared with their parental antibodies, and retain the functionality of parental antibodies in biological assays. In addition, the bispecific heterodimeric IgG derived from anti-HER2 and anti-EGF receptor (EGFR) antibody was shown to induce a higher level of receptor internalization than the combination of two parental antibodies. Mouse xenograft BxPC-3, Panc-1, and Calu-3 human tumor models showed that the heterodimeric IgGs strongly inhibited tumor growth. The described approach can be used to generate tools from two pre-existent antibodies and explore the potential of bispecific antibodies. The asymmetrically engineered Fc variants for antibody-dependent cellular cytotoxicity enhancement could be embedded in monovalent bispecific heterodimeric IgG to make best-in-class therapeutic antibodies. PMID:25583986

  10. A Novel Antibody Engineering Strategy for Making Monovalent Bispecific Heterodimeric IgG Antibodies by Electrostatic Steering Mechanism*

    PubMed Central

    Liu, Zhi; Leng, Esther C.; Gunasekaran, Kannan; Pentony, Martin; Shen, Min; Howard, Monique; Stoops, Janelle; Manchulenko, Kathy; Razinkov, Vladimir; Liu, Hua; Fanslow, William; Hu, Zhonghua; Sun, Nancy; Hasegawa, Haruki; Clark, Rutilio; Foltz, Ian N.; Yan, Wei

    2015-01-01

    Producing pure and well behaved bispecific antibodies (bsAbs) on a large scale for preclinical and clinical testing is a challenging task. Here, we describe a new strategy for making monovalent bispecific heterodimeric IgG antibodies in mammalian cells. We applied an electrostatic steering mechanism to engineer antibody light chain-heavy chain (LC-HC) interface residues in such a way that each LC strongly favors its cognate HC when two different HCs and two different LCs are co-expressed in the same cell to assemble a functional bispecific antibody. We produced heterodimeric IgGs from transiently and stably transfected mammalian cells. The engineered heterodimeric IgG molecules maintain the overall IgG structure with correct LC-HC pairings, bind to two different antigens with comparable affinity when compared with their parental antibodies, and retain the functionality of parental antibodies in biological assays. In addition, the bispecific heterodimeric IgG derived from anti-HER2 and anti-EGF receptor (EGFR) antibody was shown to induce a higher level of receptor internalization than the combination of two parental antibodies. Mouse xenograft BxPC-3, Panc-1, and Calu-3 human tumor models showed that the heterodimeric IgGs strongly inhibited tumor growth. The described approach can be used to generate tools from two pre-existent antibodies and explore the potential of bispecific antibodies. The asymmetrically engineered Fc variants for antibody-dependent cellular cytotoxicity enhancement could be embedded in monovalent bispecific heterodimeric IgG to make best-in-class therapeutic antibodies. PMID:25583986

  11. Bio-Inspired Metal-Coordination Dynamics: A Unique Tool for Engineering Soft Matter Mechanics

    NASA Astrophysics Data System (ADS)

    Holten-Andersen, Niels

    Growing evidence supports a critical role of metal-coordination in soft biological material properties such as self-healing, underwater adhesion and autonomous wound plugging. Using bio-inspired metal-binding polymers, initial efforts to mimic these properties with metal-coordination crosslinked polymer materials have shown promise. In addition, with polymer network mechanics strongly coupled to coordinate crosslink dynamics material properties can be easily tuned from visco-elastic fluids to solids. Given their exploitation in desirable material applications in Nature, bio-inspired metal-coordinate complex crosslinking provides an opportunity to further advance synthetic polymer materials design. Early lessons from this pursuit are presented.

  12. 3D chiral nanoplasmonics: fabrication, chiroptic engineering, mechanism, and application in enantioselection (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Huang, Zhifeng

    2015-09-01

    Chirality does naturally exist, and the building blocks of life (e.g. DNA, proteins, peptides and sugars) are usually chiral. Chirality inherently imposes chemical/biological selectivity on functional molecules; hence the discrimination in molecular chirality from an enantiomer to the other mirror image (i.e. enantioselection) has fundamental and application significance. Enantiomers interact with left and right handed circularly polarized light in a different manner with respect to optical extinction; hence, electronic circular dichroism (ECD) has been widely used for enantioselection. However, enantiomers usually have remarkably low ECD intensity, mainly owing to the small electric transition dipole moment induced by molecular sizes compared to the ECD-active wavelength in the UV-visible-near IR region. To enhance ECD magnitude, recently it has being developed 3D chiral nanoplasmonic structures having a helical path, and the dimensions are comparable to the ECD wavelength. However, it is still ambiguous the origin of 3D chiroplasmonics, and there is a lack of studying the interaction of 3D chiroplasmoncs with enantiomers for the application of enantioselection. Herein, we will present a one-step fabrication of 3D silver nanospirals (AgNSs) via low-substrate-temperature glancing angle deposition. AgNSs can be deposited on a wide range of substrates (including transparent and flexible substrates), in an area on the order of cm2. A set of spiral dimensions (such as spiral pitches, number of turns and handedness) have been easily engineered to tune the chiroptic properties, leading to studying the chiroplasmonic principles together with finite element simulation and the LC model. At the end, it will be demonstrated that 3D chiroplasmonics can differentiate molecular chirality of enantiomers with dramatic enhancement in the anisotropy g factor. This study opens a door to sensitively discriminate enantiomer chirality.

  13. Engineering Multi-scale Electrospun Structure for Integration into Architected 3-D Nanofibers for Cimex Annihilation: Fabrication and Mechanism Study

    NASA Astrophysics Data System (ADS)

    He, Shan; Zhang, Linxi; Liu, Ying; Rafailovich, Miriam; Garcia Center for Polymers at Engineered Interfaces Team

    In this study, engineered electrospun scaffolds with fibers oriented with designed curvature in three dimensions (3D) including the looped structure were developed based on the principle of electrostatic repulsion. Here we illustrate that 3D electrospun recycled polystyrene fibers could closely mimic the unique architectures of multi-direction and multi-layer nano-spiderweb. In contrast to virgin PS, the recycled PS (Dart Styrofoam) are known to contain zinc stearate which acts as a surfactant resulting in higher electrical charge and larger fiber curvature, hence, lower modulus. The surfactant, which is known to decrease the surface tension, may have also been effective at decreasing the confinement of the PS, where chain stretching was shown to occur, in response to the high surface tension at the air interface. Three dimensional flexible architecture with complex structures are shown to be necessary in order to block the motion of Cimex lectularius. Here we show how an engineered electrospun network of surfactant modified polymer fibers with calculated dimensions can be used to immobilize the insects. The mechanical response of the fibers has to be specifically tailored so that it is elastically deformed, without fracturing or flowing. Carefully controlling and tailoring the electrospinning parameters we can now utilize architected 3D nanofiber to create an environmental-friendly Cimex immobilization device which can lead to annihilation solution for all the other harmful insects.

  14. Advanced Propfan Engine Technology (APET) definition study, single and counter-rotation gearbox/pitch change mechanism design

    NASA Technical Reports Server (NTRS)

    Anderson, R. D.

    1985-01-01

    Single-rotation propfan-powered regional transport aircraft were studied to identify key technology development issues and programs. The need for improved thrust specific fuel consumption to reduce fuel burned and aircraft direct operating cost is the dominant factor. Typical cycle trends for minimizing fuel consumption are reviewed, and two 10,000 shp class engine configurations for propfan propulsion systems for the 1990's are presented. Recommended engine configurations are both three-spool design with dual spool compressors and free power turbines. The benefits of these new propulsion system concepts were evaluated using an advanced airframe, and results are compared for single-rotation propfan and turbofan advanced technology propulsion systems. The single-rotation gearbox is compared to a similar design with current technology to establish the benefits of the advanced gearbox technology. The conceptual design of the advanced pitch change mechanism identified a high pressure hydraulic system that is superior to the other contenders and completely external to the gearboxes.

  15. Scaffold microstructure effects on functional and mechanical performance: Integration of theoretical and experimental approaches for bone tissue engineering applications.

    PubMed

    Cavo, Marta; Scaglione, Silvia

    2016-11-01

    The really nontrivial goal of tissue engineering is combining all scaffold micro-architectural features, affecting both fluid-dynamical and mechanical performance, to obtain a fully functional implant. In this work we identified an optimal geometrical pattern for bone tissue engineering applications, best balancing several graft needs which correspond to competing design goals. In particular, we investigated the occurred changes in graft behavior by varying pore size (300μm, 600μm, 900μm), interpore distance (equal to pore size or 300μm fixed) and pores interconnection (absent, 45°-oriented, 90°-oriented). Mathematical considerations and Computational Fluid Dynamics (CFD) tools, here combined in a complete theoretical model, were carried out to this aim. Poly-lactic acid (PLA) based samples were realized by 3D printing, basing on the modeled architectures. A collagen (COL) coating was also realized on grafts surface and the interaction between PLA and COL, besides the protein contribution to graft bioactivity, was evaluated. Scaffolds were extensively characterized; human articular cells were used to test their biocompatibility and to evaluate the theoretical model predictions. Grafts fulfilled both the chemical and physical requirements. Finally, a good agreement was found between the theoretical model predictions and the experimental data, making these prototypes good candidates for bone graft replacements. PMID:27524090

  16. The Hybrid Sterling Engine: boosting photovoltaic efficiency and deriving mechanical work from fluid expansion and heat capture

    NASA Astrophysics Data System (ADS)

    Beets, Nathan; Wake Forest CenterNanotechnology; Molecular Materials Team; Fraunhofer Institute Collaboration

    2015-11-01

    Two major problems with many third generation photovoltaics is their complex structure and greater expense for increased efficiency. Spectral splitting devices have been used by many with varying degrees of success to collect more and more of the spectrum, but simple, efficient, and cost-effective setups that employ spectral splitting remain elusive. This study explores this problem, presenting a solar engine that employs stokes shifting via laser dyes to convert incident light to the wavelength bandgap of the solar cell and collects the resultant infrared radiation unused by the photovoltaic cell as heat in ethylene glycol or glycerin. When used in conjunction with micro turbines, fluid expansion creates mechanical work, and the temperature difference between the cell and the environment is made available for use. The effect of focusing is also observed as a means to boost efficiency via concentration. Experimental results from spectral scans, vibrational voltage analysis of the PV itself and temperature measurements from a thermocouple are all compared to theoretical results using a program in Mathematica written to model refraction and lensing in the devices used, a quantum efficiency test of the cells, the absorption and emission curves of the dues used to determine the spectrum shift, and the various equations for fill factor, efficiency, and current in different setups. An efficiency increase well over 50% from the control devices is observed, and a new solar engine proposed.

  17. Directing epithelial to mesenchymal transition through engineered microenvironments displaying orthogonal adhesive and mechanical cues.

    PubMed

    Markowski, Marilyn C; Brown, Ashley C; Barker, Thomas H

    2012-08-01

    Cell interactions with their extracellular matrix (ECM) microenvironments play a major role in directing cellular processes that can drive wound healing and tissue regeneration but, if uncontrolled, lead to pathological progression. One such process, epithelial to mesenchymal transition (EMT), if finely controlled could have significant potential in regenerative medicine approaches. Despite recent findings that highlight the influence of biochemical and mechanical properties of the ECM on EMT, it is still unclear how these two orthogonal cues act synergistically to control epithelial cell phenotype. Here, we cultured lung epithelial cells on combinations of different mutants of fibronectin's cell binding domain that preferentially engage specific integrins and substrates of varying stiffness. Our results suggest that while stiff substrates induce spontaneous EMT, this response can be overcome by with fragments of fibronectin that support α3 and α5 integrin engagement. Furthermore, we found that substrate-induced EMT correlates with transforming growth factor beta activation by resident epithelial cells and is dependent on Rho/ROCK signaling. Suppressing cell-contractility was sufficient to maintain an epithelial phenotype. Our results suggest that integrin-specific engagement of fibronectin adhesive domains and the mechanics of the ECM act synergistically to direct EMT. PMID:22615133

  18. Effects of Matrix Alignment and Mechanical Constraints on Cellular Behavior in 3D Engineered Microtissues

    NASA Astrophysics Data System (ADS)

    Bose, Prasenjit; Eyckmans, Jeroen; Chen, Christopher; Reich, Daniel

    The adhesion of cells to the extracellular matrix (ECM) plays a crucial role in a variety of cellular functions. The main building blocks of the ECM are 3D networks of fibrous proteins whose structure and alignments varies with tissue type. However, the impact of ECM alignment on cellular behaviors such as cell adhesion, spreading, extension and mechanics remains poorly understood. We present results on the development of a microtissue-based system that enables control of the structure, orientation, and degree of fibrillar alignment in 3D fibroblast-populated collagen gels. The tissues self-assemble from cell-laden collagen gels placed in micro-fabricated wells containing sets of elastic pillars. The contractile action of the cells leads to controlled alignment of the fibrous collagen, depending on the number and location of the pillars in each well. The pillars are elastic, and are utilized to measure the contractile forces of the microtissues, and by incorporating magnetic material in selected pillars, time-varying forces can be applied to the tissues for dynamic stimulation and measurement of mechanical properties. Results on the effects of varying pillar shape, spacing, location, and stiffness on microtissue organization and contractility will be presented. This work is supported by NSF CMMI-1463011.

  19. Cellular Targets and Mechanisms in the Cytotoxic Action of Non-biodegradable Engineered Nanoparticles

    PubMed Central

    Fröhlich, Eleonore

    2013-01-01

    The use of nanoparticles (NPs) has improved the quality of many industrial, pharmaceutical, and medical products. Increased surface reactivity, a major reason for the positive effects of NPs, may, on the other hand, also cause adverse biological effects. Almost all non-biodegradable NPs cause cytotoxic effects but employ quite different modes of action. The relation of biodegradable or loaded NPs to cytotoxic mechanism is more difficult to identify because effects may by caused by the particles or degradation products thereof. This review introduces problems of NPs in conventional cytotoxicity testing (changes of particle parameters in biological fluids, cellular dose, cell line and assay selection). Generation of reactive oxygen and nitrogen species by NPs and of metal ions due to dissolution of the NPs is discussed as a cause for cytotoxicity. The effects of NPs on plasma membrane, mitochondria, lysosomes, nucleus, and intracellular proteins as cellular targets for cytotoxicity are summarized. The comparison of the numerous studies on the mechanism of cellular effects shows that, although some common targets have been identified, other effects are unique for particular NPs or groups of NPs. While titanium dioxide NPs appear to act mainly by generation of reactive oxygen and nitrogen species, biological effects of silver and iron oxide are caused by both reactive species and free metal ions. NPs lacking heavy metals, such as carbon nanotubes and polystyrene particles, interfere with cell metabolism mainly by binding to macromolecules. PMID:24160294

  20. Proceedings of the ninth international conference on offshore mechanics and Arctic engineering, 1990

    SciTech Connect

    Chakrabarti, S.K. ); Maeda, H. ); Aage, C. ); Nielsen, F.G. )

    1990-01-01

    The Offshore Technology Symposium covers the following subjects: ocean waves, hydrodynamic forces, nonlinear hydrodynamics, fluid structure interaction, motions of floating structures, compliant structures, risers/moorings/cables, structural mechanics/analysis, design methods of structures, prototype structures, and computer technology/expert systems. The session on ocean waves includes numerical simulation, irregular and hurricane waves, laboratory data on nonlinear wave groups, and measurement techniques, as well as offshore field data. There are numerous papers on hydrodynamics and nonlinear hydrodynamics. They include analytical, numerical, and experimental research on fixed and moving offshore structures. The sessions of the fluid structure interaction and motions of floating structures mainly deal with the dynamics of floating offshore structures. These papers are followed by compliant structures and risers and mooring lines. There is one session on structural mechanics dealing with structural member loading effect and structure/soil interaction problems. Design methods of different offshore structures including jackets, concrete platforms, and articulated and guyed towers have been included. Also, several prototype structures have been discussed here. Finally, the session on computer technology includes such topics as automation, computer modeling, and expert systems.

  1. Adaptive engineering of a hyperthermophilic archaeon on CO and discovering the underlying mechanism by multi-omics analysis

    PubMed Central

    Lee, Seong Hyuk; Kim, Min-Sik; Lee, Jae-Hak; Kim, Tae Wan; Bae, Seung Seob; Lee, Sung-Mok; Jung, Hae Chang; Yang, Tae-Jun; Choi, Ae Ran; Cho, Yong-Jun; Lee, Jung-Hyun; Kwon, Kae Kyoung; Lee, Hyun Sook; Kang, Sung Gyun

    2016-01-01

    The hyperthermophilic archaeon Thermococcus onnurineus NA1 can grow and produce H2 on carbon monoxide (CO) and its H2 production rates have been improved through metabolic engineering. In this study, we applied adaptive evolution to enhance H2 productivity. After over 150 serial transfers onto CO medium, cell density, CO consumption rate and H2 production rate increased. The underlying mechanism for those physiological changes could be explained by using multi-omics approaches including genomic, transcriptomic and epigenomic analyses. A putative transcriptional regulator was newly identified to regulate the expression levels of genes related to CO oxidation. Transcriptome analysis revealed significant changes in the transcript levels of genes belonging to the categories of transcription, translation and energy metabolism. Our study presents the first genome-scale methylation pattern of hyperthermophilic archaea. Adaptive evolution led to highly enhanced H2 productivity at high CO flow rates using synthesis gas produced from coal gasification. PMID:26975345

  2. Adaptive engineering of a hyperthermophilic archaeon on CO and discovering the underlying mechanism by multi-omics analysis.

    PubMed

    Lee, Seong Hyuk; Kim, Min-Sik; Lee, Jae-Hak; Kim, Tae Wan; Bae, Seung Seob; Lee, Sung-Mok; Jung, Hae Chang; Yang, Tae-Jun; Choi, Ae Ran; Cho, Yong-Jun; Lee, Jung-Hyun; Kwon, Kae Kyoung; Lee, Hyun Sook; Kang, Sung Gyun

    2016-01-01

    The hyperthermophilic archaeon Thermococcus onnurineus NA1 can grow and produce H2 on carbon monoxide (CO) and its H2 production rates have been improved through metabolic engineering. In this study, we applied adaptive evolution to enhance H2 productivity. After over 150 serial transfers onto CO medium, cell density, CO consumption rate and H2 production rate increased. The underlying mechanism for those physiological changes could be explained by using multi-omics approaches including genomic, transcriptomic and epigenomic analyses. A putative transcriptional regulator was newly identified to regulate the expression levels of genes related to CO oxidation. Transcriptome analysis revealed significant changes in the transcript levels of genes belonging to the categories of transcription, translation and energy metabolism. Our study presents the first genome-scale methylation pattern of hyperthermophilic archaea. Adaptive evolution led to highly enhanced H2 productivity at high CO flow rates using synthesis gas produced from coal gasification. PMID:26975345

  3. OMAE 1996 -- Proceedings of the 15. international conference on offshore mechanics and arctic engineering. Volume 4: Arctic/polar technology

    SciTech Connect

    Nixon, W.A.; Sodhi, D.S.; Kennedy, K.P.; Bugno, W.

    1996-12-01

    Volume 4 contains papers on the following topics: arctic/polar technology and development; ice properties; ice engineering; applied ice mechanics; ice-structure interaction; arctic structures and operations; frozen soil properties; and Russian Arctic development. In addition to the regular topics covered in OMAE conferences, there has been a special workshop as part of this year`s conference. In keeping with issues of current interest, there is a workshop on development of oil resources in the Russian Arctic. Over two days, papers dealing with development of oil and gas resources in the Russian Arctic are presented. Volume 4 contains papers from this workshop. Some of the papers have been processed separately for inclusion on the data base.

  4. Beyond the VAD: Human Factors Engineering for Mechanically Assisted Circulation in the 21st Century.

    PubMed

    Throckmorton, Amy L; Patel-Raman, Sonna M; Fox, Carson S; Bass, Ellen J

    2016-06-01

    Thousands of ventricular assist devices (VADs) currently provide circulatory support to patients worldwide, and dozens of heart pump designs for adults and pediatric patients are under various stages of development in preparation for translation to clinical use. The successful bench-to-bedside development of a VAD involves a structured evaluation of possible system states, including human interaction with the device and auxiliary component usage in the hospital or home environment. In this study, we review the literature and present the current landscape of preclinical design and assessment, decision support tools and procedures, and patient-centered therapy. Gaps of knowledge are identified. The study findings support the need for more attention to user-centered design approaches for medical devices, such as mechanical circulatory assist systems, that specifically involve detailed qualitative and quantitative assessments of human-device interaction to mitigate risk and failure. PMID:26511100

  5. Mechanisms of branching reactions in melanin formation - Ab initio quantum engineering approach -

    NASA Astrophysics Data System (ADS)

    Kishida, Ryo; Menez Aspera, Susan; Kasai, Hideaki

    Melanin, a pigment found in animals, consists of two types of oligomeric unit: eumelanin and pheomelanin. The color of the skin, the hair, and the eyes is controlled by the ratio of eumelanin/pheomelanin production. Especially, dopachrome and dopaquinone are the precursor molecules of melanin which directly affect the composition of melanin through their branching reactions. Dopachrome is converted into two possible monomers of eumelanin. Dopaquinone can undergo both eumelanin and pheomelanin synthesis. To understand the mechanisms and controlling factors that govern the conversions, reactions of the two molecules are investigated using density functional theory-based first-principles calculations. Our results deepen mechanistic understanding of the reactions and open possibilities to design properties and functions of melanin. In this talk, we will discuss about the competitions of the branching reactions.

  6. Coal Chemistry for Mechanical Engineers: From Macromolecular Thermodynamics to Reservoir Simulation

    SciTech Connect

    Romanov, V.

    2007-05-01

    In pilot trials and commercial scale field demonstrations of CO2 storage in coal seams, quite often unexpected problems with coal swelling around injector and reducing injection efficiency (e.g., Allison unit in the San Juan Basin, RECOPOL in Poland, Hokkaido project in Japan, etc.) can stall or even terminate the site development. To avoid the costly mistakes with the prospective site evaluation, the state of the art in reservoir modeling needs to be improved by taking into account coal properties at the macromolecular level. The current models are based on the rock mechanics, which ignores decades of experimental and theoretical studies of interaction between coal and injected fluids. A pseudopolymer approach is introduced to the modelers as a viable alternative, especially, at medium to high fluid pressures. Further, it is discussed how the thermodynamics of CO2 dissolution in the macromolecular network of the coal matrix can be incorporated into geomechanical models.

  7. Strain Engineered Direct-indirect Band Gap Transition and its Mechanism in 2D Phosphorene

    NASA Astrophysics Data System (ADS)

    Peng, Xihong; Wei, Qun; Copple, Andrew

    Phosphorene, a two-dimensional puckered honeycomb structure of black phosphorus, showed promising properties for applications in nano-electronics. In this work, we report strain effect on the electronic band structure of phosphorene, using first principles density-functional theory (DFT) including standard DFT and hybrid functional methods. It was found that phosphorene can withstand a tensile strain up to 30%. The band gap of phosphorene experiences a direct-indirect-direct transition when axial strain is applied. The origin of the gap transition was revealed and a general mechanism was developed to explain energy shifts with strain according to the bond nature of near-band-edge electronic orbitals. Effective masses of carriers in the armchair direction are an order of magnitude smaller than that of the zigzag axis indicating the armchair direction is favored for carrier transport. Ref: X.-H. Peng, Qun Wei, A. Copple, Phys. Rev. B 90, 085402 (2014).

  8. Engineering the Cyanobacterial Carbon Concentrating Mechanism for Enhanced CO2 Capture and Fixation

    SciTech Connect

    Sandh, Gustaf; Cai, Fei; Shih, Patrick; Kinney, James; Axen, Seth; Salmeen, Annette; Zarzycki, Jan; Sutter, Markus; Kerfeld, Cheryl

    2011-06-02

    In cyanobacteria CO2 fixation is localized in a special proteinaceous organelle, the carboxysome. The CO2 fixation enzymes are encapsulated by a selectively permeable protein shell. By structurally and functionally characterizing subunits of the carboxysome shell and the encapsulated proteins, we hope to understand what regulates the shape, assembly and permeability of the shell, as well as the targeting mechanism and organization of the encapsulated proteins. This knowledge will be used to enhance CO2 fixation in both cyanobacteria and plants through synthetic biology. The same strategy can also serve as a template for the production of modular synthetic bacterial organelles. Our research is conducted using a variety of techniques such as genomic sequencing and analysis, transcriptional regulation, DNA synthesis, synthetic biology, protein crystallization, Small Angle X-ray Scattering (SAXS), protein-protein interaction assays and phenotypic characterization using various types of cellular imaging, e.g. fluorescence microscopy, Transmission Electron Microscopy (TEM), and Soft X-ray Tomography (SXT).

  9. Cyanobacterial CO2-concentrating mechanism components: function and prospects for plant metabolic engineering.

    PubMed

    Long, Benedict M; Rae, Benjamin D; Rolland, Vivien; Förster, Britta; Price, G Dean

    2016-06-01

    Global population growth is projected to outpace plant-breeding improvements in major crop yields within decades. To ensure future food security, multiple creative efforts seek to overcome limitations to crop yield. Perhaps the greatest limitation to increased crop yield is photosynthetic inefficiency, particularly in C3 crop plants. Recently, great strides have been made toward crop improvement by researchers seeking to introduce the cyanobacterial CO2-concentrating mechanism (CCM) into plant chloroplasts. This strategy recognises the C3 chloroplast as lacking a CCM, and being a primordial cyanobacterium at its essence. Hence the collection of solute transporters, enzymes, and physical structures that make cyanobacterial CO2-fixation so efficient are viewed as a natural source of genetic material for C3 chloroplast improvement. Also we highlight recent outstanding research aimed toward the goal of introducing a cyanobacterial CCM into C3 chloroplasts and consider future research directions. PMID:26999306

  10. RecA: Regulation and Mechanism of a Molecular Search Engine.

    PubMed

    Bell, Jason C; Kowalczykowski, Stephen C

    2016-06-01

    Homologous recombination maintains genomic integrity by repairing broken chromosomes. The broken chromosome is partially resected to produce single-stranded DNA (ssDNA) that is used to search for homologous double-stranded DNA (dsDNA). This homology driven 'search and rescue' is catalyzed by a class of DNA strand exchange proteins that are defined in relation to Escherichia coli RecA, which forms a filament on ssDNA. Here, we review the regulation of RecA filament assembly and the mechanism by which RecA quickly and efficiently searches for and identifies a unique homologous sequence among a vast excess of heterologous DNA. Given that RecA is the prototypic DNA strand exchange protein, its behavior affords insight into the actions of eukaryotic RAD51 orthologs and their regulators, BRCA2 and other tumor suppressors. PMID:27156117

  11. Rates and mechanisms of optic contamination in the EUV engineering test stand

    NASA Astrophysics Data System (ADS)

    Grunow, Philip A.; Klebanoff, Leonard E.; Graham, Samuel, Jr.; Haney, Steven J.; Clift, W. Miles

    2003-06-01

    The EUV Engineering Test Stand (ETS) is a full field, alpha class Extreme Ultraviolet Lithography (EUVL) tool that has demonstrated the printing of 70 nm resolution scanned images. The tool employs Mo/Si multilayer optics that reflect EUV radiation (13.4nm / 92.5eV) with ~67% peak reflectance per optic. For good reflectivity, many (greater than or equal to 40)Mo/Si layers must be present. Consequently, processes such as plasma induced multilayer erosion, which reduces the number of bilayer pairs on plasma facing optics, need to be understood. Since most materials readily absorb EUV photons, it is important to prevent contamination of mirror surfaces with EUV absorbing material. Contamination can occur by EUV photons "cracking" hydrocarbons or other species absorbed on the optical surfaces. The first ETS condenser component, referred to as C1, is coated with Mo/Si multilayers. Data collected from Mo/Si witness plates placed at the C1 position indicate erosion, using the Xe Laser Produced Plasma (LPP) spray jet, of 1 bilayer per ~15 million shots. Preliminary experiments with a filament jet yielded a significantly higher erosion rate. In the spray jet studies, erosion was found to depend sensitively on the composition of the residual background environment. Addition of low levels, ~7x10-7 Torr, of H2O to the vacuum background produced oxidation of the Si cap, and significantly slowed spray jet induced erosion. Operation of the plasma changed the environment in the Illuminator Chamber from oxidizing to carbonizing, thereby changing the nature of the contamination found environment at the C3 optic which does not view the plasma directly (and therefore does not erode). The change in environment is attributed to plasma induced outgassing of fluorocarbons in the Illuminator. Due to the non zero conductance between the Illuminator and Main Chambers, fluorocarbons were also found in the Main Chamber during Xe LPP operation. RGA data are presented that document the effect

  12. Rates and mechanisms of optic contamination in the EUVL engineering test stand

    NASA Astrophysics Data System (ADS)

    Grunow, Philip A.; Klebanoff, Leonard E.; Graham, Samuel, Jr.; Haney, Steven J.; Clift, W. Miles

    2003-06-01

    The EUV Engineering Test Stand (ETS) is a full-field, alpha-class Extreme Ultraviolet Lithography (EUVL) tool that has demonstrated the printing of 70 nm resolution scanned images. The tool employs Mo/Si multilayer optics that reflect EUV radiation (13.4nm / 92.5eV) with ~67% peak reflectance per optic. For good reflectivity, many (≥40)Mo/Si layers must be present. Consequently, processes such as plasma-induced multilayer erosion, which reduces the number of bilayer pairs on plasma-facing optics, need to be understood. Since most materials readily absorb EUV photons, it is important to prevent contamination of mirror surfaces with EUV absorbing material. Contamination can occur by EUV photons "cracking" hydrocarbons or other species absorbed on the optical surfaces. The first ETS condenser component, referred to as C1, is coated with Mo/Si multilayers. Data collected from Mo/Si witness plates placed at the C1 position indicate erosion, using the Xe Laser Produced Plasma (LPP) spray jet, of 1 bilayer per ~15 million shots. Preliminary experiments with a filament jet yielded a significantly higher erosion rate. In the spray jet studies, erosion was found to depend sensitively on the composition of the residual background environment. Addition of low levels, ~7x10-7 Torr, of H2O to the vacuum background produced oxidation of the Si cap, and significantly slowed spray jet-induced erosion. Operation of the plasma changed the environment in the Illuminator Chamber from oxidizing to carbonizing, thereby changing the nature of the contamination found environment at the C3 optic which does not view the plasma directly (and therefore does not erode). The change in environment is attributed to plasma-induced outgassing of fluorocarbons in the Illuminator. Due to the non-zero conductance between the Illuminator and Main Chambers, fluorocarbons were also found in the Main Chamber during Xe LPP operation. RGA data are presented that document the effect. In the presence of such

  13. Quiet Clean Short-haul Experimental Engine (QCSEE): The aerodynamic and mechanical design of the QCSEE under-the-wing fan

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The design, fabrication, and testing of two experimental high bypass geared turbofan engines and propulsion systems for short haul passenger aircraft are described. The aerodynamic and mechanical design of a variable pitch 1.34 pressure ratio fan for the under the wing (UTW) engine are included. The UTW fan was designed to permit rotation of the 18 composite fan blades into the reverse thrust mode of operation through both flat pitch and stall pitch directions.

  14. Quantum-mechanical engines working with an ideal gas with a finite number of particles confined in a power-law trap

    NASA Astrophysics Data System (ADS)

    Wang, Jianhui; Ma, Yongli; He, Jizhou

    2015-07-01

    Based on quantum thermodynamic processes, we make a quantum-mechanical (QM) extension of the typical heat engine cycles, such as the Carnot, Brayton, Otto, Diesel cycles, etc., with no introduction of the concept of temperature. When these QM engine cycles are implemented by an ideal gas confined in an arbitrary power-law trap, a relation between the quantum adiabatic exponent and trap exponent is found. The differences and similarities between the efficiency of a given QM engine cycle and its classical counterpart are revealed and discussed.

  15. Thermo-Mechanical Response of a TRISO Fuel Particle in a Fusion/Fission Engine for Incineration of Weapons Grade Plutonium

    SciTech Connect

    Caro, M; DeMange, P; Marian, J; Caro, A

    2009-12-08

    The Laser Inertial Fusion-based (LIFE) engine is an advanced energy concept under development at Lawrence Livermore National Laboratory (LLNL). LIFE engine could be used to drive a subcritical fission blanket with fertile or fissile fuel. Current LIFE engine designs envisages fuel in pebble bed form with TRISO (tristructural isotropic) particles embedded in a graphite matrix, and pebbles flowing in molten salt Flibe (2LiF+BeF{sub 2}) coolant at T {approx} 700C. Weapons-grade plutonium (WGPu) fuel is an attractive option for LIFE engine involving the achievement of high fractional burnups in a short lifetime frame. However, WGPu LIFE engine operating conditions of high neutron fast fluence, high radiation damage, and high Helium and Hydrogen production pose severe challenges for typical TRISO particles. The thermo-mechanical fuel performance code HUPPCO (High burn-Up fuel Pebble Performance COde) currently under development accounts for spatial and time dependence of the material elastic properties, temperature, and irradiation swelling and creep mechanisms. In this work, some aspects of the thermo-mechanical response of TRISO particles used for incineration of weapons grade fuel in LIFE engine are analyzed. Preliminary results show the importance of developing reliable high-fidelity models of the performance of these new fuel designs and the need of new experimental data relevant to WGPu LIFE conditions.

  16. Grain boundary engineering in a thermo-mechanically processed Nb-stabilized austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Yunquera, A.; Jorge-Badiola, D.; Gutiérrez, I.; Iza-Mendia, A.

    2015-04-01

    Three different thermo-mechanical strategies—annealing, strain recrystallization and strain annealing—were applied to a Nb-stabilized 304H austenitic stainless steel in order to study their effects on grain boundary character distribution (GBCD). An Electron Backscatter Diffraction (EBSD) analysis revealed specific combinations of cold reduction-temperature-time that favor annealing twinning. A uniform increase in microstructural size and special boundaries (particularly for Σ3, Σ9 and Σ27 boundaries) was achieved under strain annealing conditions (low cold reductions) and long times at high temperatures (≥ 990°C). These conditions provide a high fraction of special boundaries (about 80%), which replace the random grain boundary network and thus optimize the GBCD. The profuse presence of Σ3n boundaries is attributed to the geometric interaction of twin-related variants during grain boundary migration. In addition to all this, precipitation takes place at the temperature range where optimum GBCD is achieved. The significance of precipitation in the different strategies was also tackled.

  17. Recombinant Human Lactoferrin as a biomaterial for Bone Tissue Engineering: Mechanism of Antiapoptotic and Osteogenic Activity

    PubMed Central

    Amini, Ashley A.

    2014-01-01

    Lactoferrin is a bioactive globular protein with unique properties towards musculo-skeletal cells and anabolic to bone in vivo. Even though the potent anti-apoptotic and osteogenic activity of lactoferrin has been reported, the mechanism of action has not been fully elucidated. The study demonstrated that the anti-apoptotic effect of rhLF towards MC3T3 pre-osteoblast cells is mediated by Wnt5a/PKA pathway and the stabilization of β-catenin by rhLF is dependent on PKA/LRP6 signaling pathway. The study also investigated the feasibility of developing rhLF as a biomaterial for cell delivery. The injectable rhLF cell delivery vehicles were prepared by enzymatic crosslinking of tyramine-modified rhLF in the presence of hydrogen peroxide and horseradish peroxidase. The modified rhLF showed bioactivity similar to unmodified rhLF. The rhLF gels supported encapsulated MC3T3 cell viability, proliferation and differentation, as well as phosphorylation of signaling proteins. In conclusion, the study demonstrated the involvement of Wnt5a, LRP6 and PKA signaling in rhLF mediated bioactivity towards MC3T3 cells and the feasibility of developing an injectable cell delivery vehicle from rhLF. PMID:24352833

  18. Biodrying for mechanical-biological treatment of wastes: a review of process science and engineering.

    PubMed

    Velis, C A; Longhurst, P J; Drew, G H; Smith, R; Pollard, S J T

    2009-06-01

    Biodrying is a variation of aerobic decomposition, used within mechanical-biological treatment (MBT) plants to dry and partially stabilise residual municipal waste. Biodrying MBT plants can produce a high quality solid recovered fuel (SRF), high in biomass content. Here, process objectives, operating principles, reactor designs, parameters for process monitoring and control, and their effect on biodried output quality are critically examined. Within the biodrying reactors, waste is dried by air convection, the necessary heat provided by exothermic decomposition of the readily decomposable waste fraction. Biodrying is distinct from composting in attempting to dry and preserve most of biomass content of the waste matrix, rather than fully stabilise it. Commercial process cycles are completed within 7-15 days, with mostly H(2)O((g)) and CO(2) loses of ca. 25-30% w/w, leading to moisture contents of <20% w/w. High airflow rate and dehumidifying of re-circulated process air provides for effective drying. We anticipate this review will be of value to MBT process operators, regulators and end-users of SRF. PMID:19216072

  19. Lateral migration and diffusion of a mechanical engineer through emulsion of drops induced by Andy's influence

    NASA Astrophysics Data System (ADS)

    Sarkar, Kausik

    2014-11-01

    My initiation to analytical sides of Stokes flow was thorough cyclostyled notes of Andy's Stanford fluid mechanics notes distributed by Ashok Sangani when he taught a course at Hopkins. Since then, reversibility of Stokes flow and singularity solution remained with me during my research carrier. I will discuss how it and Frankel and Acrivos (1970) paper in JFM influenced my research in drop deformation and emulsion rheology at finite inertia, winning the 2009 Acrivos award by my first PhD student Xiaoyi Li. Finally, I will discuss migration of suspended particles, drops, polymers and biological cells caused by breaking of Stokes reversibility due to deformation and viscoelasticity. Here, we show that the migration is induced by the image stresslet field, as was also indicated by Dave Leighton's thesis and a paper with Smart [1991, Phys. Fluid A, 3, 21]. We relate the stresslet field to the Interface tensor, and investigate the effects of drop inclination. In contrast to a plausible notion asserted also in the literature, that reduced inclination (increased alignment with flow) decreases migration, it is shown here that reduced inclination increases the stresslet and thereby the migration velocity.

  20. Insights into transport mechanism from LeuT engineered to transport tryptophan

    SciTech Connect

    Piscitelli, Chayne L.; Gouaux, Eric

    2012-01-10

    LeuT is a bacterial homologue of the neurotransmitter:sodium symporter (NSS) family and, being the only NSS member to have been structurally characterized by X-ray crystallography, is a model protein for studying transporter structure and mechanism. Transport activity in LeuT was hypothesized to require structural transitions between open-to-out and occluded conformations dependent upon protein:ligand binding complementarity. Here, using crystallographic and functional analysis, we show that binding site modification produces changes in both structure and activity that are consistent with complementarity-dependent structural transitions to the occluded state. The mutation I359Q converts the activity of tryptophan from inhibitor to transportable substrate. This mutation changes the local environment of the binding site, inducing the bound tryptophan to adopt a different conformer than in the wild-type complex. Instead of trapping the transporter open, tryptophan binding now allows the formation of an occluded state. Thus, transport activity is correlated to the ability of the ligand to promote the structural transition to the occluded state, a step in the transport cycle that is dependent on protein:ligand complementarity in the central binding site.

  1. Mechanisms of Ricin Toxin Neutralization Revealed through Engineered Homodimeric and Heterodimeric Camelid Antibodies.

    PubMed

    Herrera, Cristina; Tremblay, Jacqueline M; Shoemaker, Charles B; Mantis, Nicholas J

    2015-11-13

    Novel antibody constructs consisting of two or more different camelid heavy-chain only antibodies (VHHs) joined via peptide linkers have proven to have potent toxin-neutralizing activity in vivo against Shiga, botulinum, Clostridium difficile, anthrax, and ricin toxins. However, the mechanisms by which these so-called bispecific VHH heterodimers promote toxin neutralization remain poorly understood. In the current study we produced a new collection of ricin-specific VHH heterodimers, as well as VHH homodimers, and characterized them for their ability neutralize ricin in vitro and in vivo. We demonstrate that the VHH heterodimers, but not homodimers were able to completely protect mice against ricin challenge, even though the two classes of antibodies (heterodimers and homodimers) had virtually identical affinities for ricin holotoxin and similar IC50 values in a Vero cell cytotoxicity assay. The VHH heterodimers did differ from the homodimers in their ability to promote toxin aggregation in solution, as revealed through analytical ultracentrifugation. Moreover, the VHH heterodimers that were most effective at promoting ricin aggregation in solution were also the most effective at blocking ricin attachment to cell surfaces. Collectively, these data suggest that heterodimeric VHH-based neutralizing agents may function through the formation of antibody-toxin complexes that are impaired in their ability to access host cell receptors. PMID:26396190

  2. A study on improving mechanical properties of porous HA tissue engineering scaffolds by hot isostatic pressing.

    PubMed

    Zhao, Jing; Xiao, Suguang; Lu, Xiong; Wang, Jianxin; Weng, Jie

    2006-12-01

    Various interconnected porous hydroxyapatite (HA) ceramic scaffolds are universally used to induct the tissue growth for bone repair and replacement, and serve to support the adhesion, transfer, proliferation and differentiation of cells. Impregnation of polyurethane sponges with a ceramic slurry is adopted to produce highly porous HA ceramic scaffolds with a 3D interconnected structure. However, high porosity always accompanies a decrease in the strength of the HA ceramic scaffolds. Therefore, it is significant to improve the strength of the HA ceramic scaffolds with highly interconnected porosity so that they are more suitable in clinical applications. In this work, highly porous HA ceramic scaffolds are first produced by the polymer impregnation approach, and subsequently further sintered by hot isostatic pressing (HIP). The phase composition, macro- and micro-porous structure, sintering and mechanical properties of the porous HA scaffolds are investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), nanoindentation analysis and compressive test. The experimental results show that the nanohardness and compressive strength of HIP-sintered porous HA ceramics are higher than those of commonly sintered HA scaffolds. The HIP technique can effectively improve the sintering property and densification of porous HA ceramic scaffolds, so inducing an increase in the compression strength. PMID:18458404

  3. Driving force transmission mechanism using a timing belt for an internal combustion engine

    SciTech Connect

    Abe, S.

    1987-11-24

    A driving force transmission mechanism is described comprising: a timing pulley having teeth, each of the teeth having a width perpendicular to a direction of movement of the teeth; and a timing belt engaging the timing pulley, the timing belt having teeth, each of the timing belt teeth having a width perpendicular to a direction of movement of the timing belt teeth; a width of the timing belt not being larger that a width of the timing pulley; the width of the teeth of the timing belt at dedendums of the teeth being larger than a width of engagement of the teeth of the timing belt with the teeth of the timing pulley; at least one of width end portions of the teeth of the timing pulley and width end portions of the teeth of the timing belt being cut out so that width end portions of the teeth of the timing belt at dedendums of the timing belt do not contact the teeth of the timing pulley.

  4. Recombinant human lactoferrin as a biomaterial for bone tissue engineering: mechanism of antiapoptotic and osteogenic activity.

    PubMed

    Amini, Ashley A; Nair, Lakshmi S

    2014-06-01

    Lactoferrin is a bioactive globular protein with unique properties towards musculo-skeletal cells and anabolic to bone in vivo. Even though the potent anti-apoptotic and osteogenic activity of lactoferrin has been reported, the mechanism of action has not been fully elucidated. The study demonstrates that the anti-apoptotic effect of rhLF towards MC3T3 pre-osteoblast cells is mediated by Wnt5a/PKA pathway and the stabilization of β-catenin by rhLF is dependent on PKA/LRP6 signaling pathway. The study also investigates the feasibility of developing rhLF as a biomaterial for cell delivery. The injectable rhLF cell delivery vehicles are prepared by enzymatic crosslinking of tyramine-modified rhLF in the presence of hydrogen peroxide and horseradish peroxidase. The modified rhLF shows bioactivity similar to unmodified rhLF. The rhLF gels support encapsulated MC3T3 cell viability, proliferation, and differentiation, as well as phosphorylation of signaling proteins. In conclusion, the study demonstrates the involvement of Wnt5a, LRP6, and PKA signaling in rhLF-mediated bioactivity towards MC3T3 cells and the feasibility of developing an injectable cell delivery vehicle from rhLF. PMID:24352833

  5. Example of good practice of a learning environment with a classroom response system in a mechanical engineering bachelor course

    NASA Astrophysics Data System (ADS)

    Lopez Arteaga, Ines; Vinken, Esther

    2013-12-01

    Results of a successful pilot study are presented, in which quizzes are introduced in a second year bachelor course for mechanical engineering students. The pilot study course entailed the basic concepts of mechanical vibrations in complex, realistic structures. The quiz is held weekly using a SharePoint application. The purpose of the quizzes is to repeat important course material, give instantaneous feedback (i.e. formative assessment), stimulate peer instruction and, as a consequence, increase the students' comprehension of the basic concepts taught in the course so that their deeper understanding of the subject matter improves. Students can earn half a point bonus, on a scale from 0 to 10, on top of their exam mark if they correctly answer 55% of all the quiz questions. The efficacy of the pilot study is determined by investigating the percentage of students that pass the course on their first attempt, i.e. the first time pass rate, and asking students for feedback through questionnaires. The first time pass rate of the students in the pilot study groups has, on average, increased significantly in comparison to groups in which the quizzes are not performed. Students indicated that the feedback from the quizzes helps them to identify gaps in their knowledge. Therefore, the pilot study is considered effective.

  6. Polyurethane/fluor-hydroxyapatite nanocomposite scaffolds for bone tissue engineering. Part I: morphological, physical, and mechanical characterization.

    PubMed

    Asefnejad, Azadeh; Behnamghader, Aliasghar; Khorasani, Mohammad Taghi; Farsadzadeh, Babak

    2011-01-01

    In this study, new nano-fluor-hydroxyapatite (nFHA)/polyurethane composite scaffolds were fabricated for potential use in bone tissue engineering. Polyester urethane samples were synthesized from polycaprolactone, hexamethylene diisocyanate, and 1,4-butanediol as chain extender. Nano fluor-hydroxyapatite (nFHA) was successfully synthesized by sol-gel method. The solid-liquid phase separation and solvent sublimation methods were used for preparation of the porous composites. Mechanical properties, chemical structure, and morphological characteristics of the samples were investigated by compressive test, Fourier transform infrared, and scanning electron microscopy (SEM) techniques, respectively. The effect of nFHA powder content on porosity and pore morphology was investigated. SEM images demonstrated that the scaffolds were constituted of interconnected and homogeneously distributed pores. The pore size of the scaffolds was in the range 50-250 μm. The result obtained in this research revealed that the porosity and pore average size decreased and compressive modulus increased with nFHA percentage. Considering morphological, physical, and mechanical properties, the scaffold with a higher ratio of nFHA has suitable potential use in tissue regeneration. PMID:21289986

  7. Mechanical and thermal stability of molecularly engineered copper-silica interfaces using organosilane nanolayers

    NASA Astrophysics Data System (ADS)

    Gandhi, Darshan Dinesh

    Future generation silicon integrated circuits requires new materials with low dielectric permittivity kappa < 2.0 and ultra-thin barrier layers (e.g., <3 nm) to create high-reliability, high-performance wiring. Preserving the structural and functional integrity of interfaces is a crucial aspect of realizing reliable integrated circuits with nanodevice components. Molecular nanolayers (MNLs) provide the unique ability to tailor interface properties by adjusting molecular termini, layering, branching or length, thereby making them attractive alternatives to conventional barrier materials. Developing a fundamental understanding of the stability and properties of MNLs at thin film interfaces, and their correlation with parameters such as terminal group chemistries molecular length and surface coverage are key to utilizing them in nanodevice applications. This work addresses some of the key challenges pertaining to modifying Cu-silica interfaces with MNLs with appropriate terminal groups. The resultant effects on, and the inter-relationships between, the chemical, mechanical and electrical properties are investigated. Modifying Cu-silica interface with MNLs results in increased Cu diffusioninduced time-to-failure when subject to electrothermal stresses. The extent of enhancement depends on the terminal chemistry of the MNLs interacting with the overlying Cu. Upon annealing, it is found that MNLs form strong covalent linkages at both Cu-MNL and MNL-silica interfaces resulting in unprecedented values of interface toughness, values exceeding 20 Jm-2. Although strong bonding at Cu-MNL and MNL-dielectric interfaces may be sufficient for blocking copper transport across polyelectrolyte MNL bilayers, strong interlayer molecular bonding is a necessary condition for interface toughening. Exposing MNLs to UV light, results in photo-oxidation of the terminal mercaptan groups. These photo-oxidized termini form strong complexes with Cu that results in enhancement by a factor-of-10

  8. Emulsion templated scaffolds with tunable mechanical properties for bone tissue engineering

    PubMed Central

    Owen, Robert; Sherborne, Colin; Paterson, Thomas; Green, Nicola H.; Reilly, Gwendolen C.; Claeyssens, Frederik

    2016-01-01

    Polymerised High Internal Phase Emulsions (PolyHIPEs) are manufactured via emulsion templating and exhibit a highly interconnected microporosity. These materials are commonly used as thin membranes for 3D cell culture. This study uses emulsion templating in combination with microstereolithography to fabricate PolyHIPE scaffolds with a tightly controlled and reproducible architecture. This combination of methods produces hierarchical structures, where the microstructural properties can be independently controlled from the scaffold macrostructure. PolyHIPEs were fabricated with varying ratios of two acrylate monomers (2-ethylhexyl acrylate (EHA) and isobornyl acrylate (IBOA)) and varying nominal porosity to tune mechanical properties. Young’s modulus, ultimate tensile stress (UTS) and elongation at failure were determined for twenty EHA/IBOA compositions. Moduli ranged from 63.01±9.13 to 0.36±0.04 MPa, UTS from 2.03±0.33 to 0.11±0.01 MPa and failure strain from 21.86±2.87% to 2.60±0.61%. Selected compositions were fabricated into macro-porous woodpile structures, plasma treated with air or acrylic acid and seeded with human embryonic stem-cell derived mesenchymal progenitor cells (hES-MPs). Confocal and two-photon microscopy confirmed cell proliferation and penetration into the micro- and macro-porous architecture. The scaffolds supported osteogenic differentiation of mesenchymal cells and interestingly, the stiffest IBOA-based scaffolds that were plasma treated with acrylic acid promoted osteogenesis more strongly than the other scaffolds. PMID:26458114

  9. Emulsion templated scaffolds with tunable mechanical properties for bone tissue engineering.

    PubMed

    Owen, Robert; Sherborne, Colin; Paterson, Thomas; Green, Nicola H; Reilly, Gwendolen C; Claeyssens, Frederik

    2016-02-01

    Polymerised High Internal Phase Emulsions (PolyHIPEs) are manufactured via emulsion templating and exhibit a highly interconnected microporosity. These materials are commonly used as thin membranes for 3D cell culture. This study uses emulsion templating in combination with microstereolithography to fabricate PolyHIPE scaffolds with a tightly controlled and reproducible architecture. This combination of methods produces hierarchical structures, where the microstructural properties can be independently controlled from the scaffold macrostructure. PolyHIPEs were fabricated with varying ratios of two acrylate monomers (2-ethylhexyl acrylate (EHA) and isobornyl acrylate (IBOA)) and varying nominal porosity to tune mechanical properties. Young's modulus, ultimate tensile stress (UTS) and elongation at failure were determined for twenty EHA/IBOA compositions. Moduli ranged from 63.01±9.13 to 0.36±0.04MPa, UTS from 2.03±0.33 to 0.11±0.01MPa and failure strain from 21.86±2.87% to 2.60±0.61%. Selected compositions were fabricated into macro-porous woodpile structures, plasma treated with air or acrylic acid and seeded with human embryonic stem-cell derived mesenchymal progenitor cells (hES-MPs). Confocal and two-photon microscopy confirmed cell proliferation and penetration into the micro- and macro-porous architecture. The scaffolds supported osteogenic differentiation of mesenchymal cells and interestingly, the stiffest IBOA-based scaffolds that were plasma treated with acrylic acid promoted osteogenesis more strongly than the other scaffolds. PMID:26458114

  10. Characterization of Mechanical and Biological Properties of 3-D Scaffolds Reinforced with Zinc Oxide for Bone Tissue Engineering

    PubMed Central

    Shuai, Cijun; Peng, Shuping

    2014-01-01

    A scaffold for bone tissue engineering should have highly interconnected porous structure, appropriate mechanical and biological properties. In this work, we fabricated well-interconnected porous β-tricalcium phosphate (β-TCP) scaffolds via selective laser sintering (SLS). We found that the mechanical and biological properties of the scaffolds were improved by doping of zinc oxide (ZnO). Our data showed that the fracture toughness increased from 1.09 to 1.40 MPam1/2, and the compressive strength increased from 3.01 to 17.89 MPa when the content of ZnO increased from 0 to 2.5 wt%. It is hypothesized that the increase of ZnO would lead to a reduction in grain size and an increase in density of the strut. However, the fracture toughness and compressive strength decreased with further increasing of ZnO content, which may be due to the sharp increase in grain size. The biocompatibility of the scaffolds was investigated by analyzing the adhesion and the morphology of human osteoblast-like MG-63 cells cultured on the surfaces of the scaffolds. The scaffolds exhibited better and better ability to support cell attachment and proliferation when the content of ZnO increased from 0 to 2.5 wt%. Moreover, a bone like apatite layer formed on the surfaces of the scaffolds after incubation in simulated body fluid (SBF), indicating an ability of osteoinduction and osteoconduction. In summary, interconnected porous β-TCP scaffolds doped with ZnO were successfully fabricated and revealed good mechanical and biological properties, which may be used for bone repair and replacement potentially. PMID:24498185

  11. Aircraft gas-turbine engines: Noise reduction and vibration control. (Latest citations from Information Services in Mechanical Engineering data base). Published Search

    SciTech Connect

    Not Available

    1992-06-01

    The bibliography contains citations concerning the design and analysis of aircraft gas turbine engines with respect to noise and vibration control. Included are studies regarding the measurement and reduction of noise at its source, within the aircraft, and on the ground. Inlet, nozzle and core aerodynamic studies are cited. Propfan, turbofan, turboprop engines, and applications in short take-off and landing (STOL) aircraft are included. (Contains a minimum of 202 citations and includes a subject term index and title list.)

  12. Mechanical Engineering Safety Note: Analysis and Control of Hazards Associated with NIF Capacitor Module Events

    SciTech Connect

    Brereton, S

    2001-08-01

    the total free oil available in a capacitor (approximately 10,900 g), on the order of 5% or less. The estimates of module pressure were used to estimate the potential overpressure in the capacitor bays after an event. It was shown that the expected capacitor bay overpressure would be less than the structural tolerance of the walls. Thus, it does not appear necessary to provide any pressure relief for the capacitor bays. The ray tracing analysis showed the new module concept to be 100% effective at containing fragments generated during the events. The analysis demonstrated that all fragments would impact an energy absorbing surface on the way out of the module. Thus, there is high confidence that energetic fragments will not escape the module. However, since the module was not tested, it was recommended that a form of secondary containment on the walls of the capacitor bays (e.g., 1.0 inch of fire-retardant plywood) be provided. Any doors to the exterior of the capacitor bays should be of equivalent thickness of steel or suitably armed with a thickness of plywood. Penetrations in the ceiling of the interior bays (leading to the mechanical equipment room) do not require additional protection to form a secondary barrier. The mezzanine and the air handling units (penetrations lead directly to the air handling units) provide a sufficient second layer of protection.

  13. Influence of tissue- and cell-scale extracellular matrix distribution on the mechanical properties of tissue-engineered cartilage.

    PubMed

    Khoshgoftar, Mehdi; Wilson, Wouter; Ito, Keita; van Donkelaar, Corrinus C

    2013-10-01

    The insufficient load-bearing capacity of today's tissue- engineered (TE) cartilage limits its clinical application. Generally, cartilage TE studies aim to increase the extracellular matrix (ECM) content, as this is thought to determine the load-bearing properties of the cartilage. However, there are apparent inconsistencies in the literature regarding the correlation between ECM content and mechanical properties of TE constructs. In addition to the amount of ECM, the spatial inhomogeneities in ECM distribution at the tissue scale as well as at the cell scale may affect the mechanical properties of TE cartilage. The relative importance of such structural inhomogeneities on mechanical behavior of TE cartilage is unknown. The aim of the present study was, therefore, to theoretically elucidate the influence of these inhomogeneities on the mechanical behavior of chondrocyte-agarose TE constructs. A validated non-linear fiber-reinforced poro-elastic swelling cartilage model that can accommodate for effects of collagen reinforcement and swelling by proteoglycans was used. At the tissue scale, ECM was gradually varied from predominantly localized in the periphery of the TE construct toward an ECM-rich inner core. The effect of these inhomogeneities in relation to the total amount of ECM was also evaluated. At the cell scale, ECM was gradually varied from localized in the pericellular area, toward equally distributed throughout the interterritorial area. Results from the tissue-scale model indicated that localization of ECM in either the construct periphery or in the inner core may reduce construct stiffness compared with that of constructs with homogeneous ECM. Such effects are more significant at high ECM amounts. At the cell scale, localization of ECM around the cells significantly reduced the overall stiffness, even at low ECM amounts. The compressive stiffness gradually increased when ECM distribution became more homogeneous and the osmotic swelling pressure in the

  14. A multicomponent bioactive tissue-engineered blood vessel: Fabrication, mechanical evaluation and biological evaluation with physiological-relevant conditions

    NASA Astrophysics Data System (ADS)

    Bonani, Walter

    The high long-term failure rate of synthetic vascular grafts in the replacement of small vessels is known to be associated with the lack of physiological signals to vascular cells causing adverse hemodynamic, inflammatory or coagulatory events. Current studies focus on developing engineered vascular devices with ability of directing cell activity in vitro and in vivo for tissue regeneration. It is also known that controlled molecule release from scaffolds can dramatically increase the scaffold ability of directing cell activities in vitro and in vivo for tissue regeneration. To address the mechanical and biological problems associated with graft materials, we demonstrated a degradable polyester-fibroin composite tubular scaffolds which shows well-integrated nanofibrous structure, endothelial-conducive surface and anisotropic mechanical property, suitable as engineered vascular constructs. Tissue regeneration needs not only functional biomolecules providing signaling cues to cells and guide tissue remodeling, but also an adequate modality of molecule delivery. In fact, healthy tissue formation requires specific signals at well-defined place and time. To develop scaffolds with multi-modal presentation of biomolecules, we patterned electrospun nanofibers over the thickness of the 3-dimensional scaffolds by programming the deposition of interpenetrating networks of degradable polymers poly(a-caprolactone) and poly(lactide-co-glycolide) acid in tailored proportion. Fluorescent model molecules, drug and growth factors were embedded in the polymeric fibers with different techniques and release profiles were obtained and discussed. Fabrication process resulted in precise gradient patterns of materials and functional biomolecules throughout the thickness of the scaffold. These graded materials showed programmable spatio-temporal control over the release. Molecule release profiles on each side of the scaffolds were used to determine the separation efficiency of molecule

  15. Applying Task-Technology Fit Model to the Healthcare Sector: a Case Study of Hospitals' Computed Tomography Patient-Referral Mechanism.

    PubMed

    Chen, Ping-Shun; Yu, Chun-Jen; Chen, Gary Yu-Hsin

    2015-08-01

    With the growth in the number of elderly and people with chronic diseases, the number of hospital services will need to increase in the near future. With myriad of information technologies utilized daily and crucial information-sharing tasks performed at hospitals, understanding the relationship between task performance and information system has become a critical topic. This research explored the resource pooling of hospital management and considered a computed tomography (CT) patient-referral mechanism between two hospitals using the information system theory framework of Task-Technology Fit (TTF) model. The TTF model could be used to assess the 'match' between the task and technology characteristics. The patient-referral process involved an integrated information framework consisting of a hospital information system (HIS), radiology information system (RIS), and picture archiving and communication system (PACS). A formal interview was conducted with the director of the case image center on the applicable characteristics of TTF model. Next, the Icam DEFinition (IDEF0) method was utilized to depict the As-Is and To-Be models for CT patient-referral medical operational processes. Further, the study used the 'leagility' concept to remove non-value-added activities and increase the agility of hospitals. The results indicated that hospital information systems could support the CT patient-referral mechanism, increase hospital performance, reduce patient wait time, and enhance the quality of care for patients. PMID:26126414

  16. Relocation and focal mechanisms of earthquakes in the south-central sector of the Aeolian Archipelago: New structural and volcanological insights

    NASA Astrophysics Data System (ADS)

    Gambino, Salvatore; Milluzzo, Vincenzo; Scaltrito, Antonio; Scarfì, Luciano

    2012-02-01

    To recognize possible spatial clusters and identify active seismogenic zones and structures in the Aeolian Archipelago, in the south of Italy, we analyzed the spatial pattern of seismicity between 1993 and 2010 in a selected area comprising Vulcano, Lipari, Salina and Filicudi and calculated 22 fault plane solutions (FPSs) for shocks with magnitude greater than 2.7. First, we computed a 1-D velocity model for this area including information from recorded earthquakes by a joint hypocenter-velocity inversion (Kissling et al., 1994). Successively, we applied the double-difference approach of Waldhauser and Ellsworth (2000), finding that a certain part of the scattered epicenter locations collapse in roughly linear features. Relocated seismicity evidenced three main alignments, oriented NNW-SSE and NE-SW at different depths that concur well with the known tectonic lineaments and focal mechanisms. A detailed discussion is focused on a seismogenetic structure, NE-SW oriented, 3-8 km deep, located in the northern area of Vulcano island. This recognized element could represent a link between magma accumulation zones, thus representing a possible preferential pathway along which magma may intrude. Two earthquake clusters, located south-west and east of Vulcano, with their focal mechanisms, highlight the Aeolian-Tindari-Letojanni Fault System seismic activity and the existence of a transitional zone going from the N-S compressive domain that dominates the Aeolian Islands to the NW-SE extensional domain characterizing the south-eastern Tyrrhenian.

  17. Quiet Clean Short-haul Experimental Engine (QCSEE). The aerodynamic and mechanical design of the QCSEE over-the-wing fan

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The aerodynamic and mechanical design of a fixed-pitch 1.36 pressure ratio fan for the over-the-wing (OTW) engine is presented. The fan has 28 blades. Aerodynamically, the fan blades were designed for a composite blade, but titanium blades were used in the experimental fan as a cost savings measure.

  18. Evaluation of the Effectiveness of the Integration of a LITEE Case Study for a Freshman Level Mechanical Engineering Course at The University of Toledo

    ERIC Educational Resources Information Center

    Franchetti, Matthew

    2011-01-01

    The purpose of this paper is to report the findings of the integration of a manufacturing case study to a freshman level mechanical engineering course at The University of Toledo. The approach to integrate this case study into the class was completed via weekly assignments analyzing the case, small group discussion, and weekly group discussion.…

  19. Computer Aided Drafting and Design, Industrial Manufacturing Technician, and Mechanical Engineering Technician and Machine Tool, Die and Moldmaking Technology. Tech Prep Competency Profile.

    ERIC Educational Resources Information Center

    Mid-East Ohio Tech Prep Consortium, Zanesville.

    This document contains competency profiles in four areas: computer-aided drafting and design; industrial manufacturing technician; mechanical engineering technician; and machine tool, die, and moldmaking technology occupations. The profiles are intended for use in articulating tech prep programs from high school through associate degrees in Ohio.…

  20. Hybrid hyaluronic acid hydrogel/poly(ɛ-caprolactone) scaffold provides mechanically favorable platform for cartilage tissue engineering studies.

    PubMed

    Mintz, Benjamin R; Cooper, James A

    2014-09-01

    Hybrid scaffolds for cartilage tissue engineering provide the potential for high stiffness properties in tension and compression while exhibiting the viscoelastic response found in hydrogels and native cartilage tissue. We investigate the impact of a hybrid scaffold fabricated from a hyaluronic acid (HA)-based hydrogel combined with porous poly(ε-caprolactone) (PCL) material formed by a particulate leaching method to study dedifferentiated chondrocyte response. The material properties of the hybrid scaffold showed mean Young's moduli in tension which were similar to human articular cartilage but not statistically different between the hybrid and porous PCL scaffolds at 2.02 and 2.07 MPa, respectively. For both the hybrid and porous PCL control scaffolds in compression at low loading frequencies (<1 Hz) and 10% strain peak amplitude the Young's moduli are not statistically distinct. However, at frequencies in the range of normal human gait from 1 to2 Hz, hybrid scaffolds exhibit significantly (p < 0.01) increased loss moduli indicating additional contribution of the viscous phase to stiffness. Dedifferentiated chondrocytes seeded onto the scaffolds exhibited a rounded morphology in hybrid scaffolds however ECM protein expression levels of collagen type I, collagen type II, and aggrecan are not different from the PCL control scaffolds. These results provide a model platform to investigate cell response to mechanical and chemical cues in a hybrid scaffold system with mechanical properties similar to human cartilage that does not contribute to differentiation in order to identify the appropriate design and development parameters to promote formation of extracellular matrix and investigate chondrocyte scaffold interactions. PMID:24115629

  1. Characterization, mechanical behavior and in vitro evaluation of a melt-drawn scaffold for esophageal tissue engineering.

    PubMed

    Tan, Yu Jun; Yeong, Wai Yee; Tan, Xipeng; An, Jia; Chian, Kerm Sin; Leong, Kah Fai

    2016-04-01

    Tubular esophageal scaffolds with fiber diameter ranging from 13.9±1.7μm to 65.7±6.2μm were fabricated from the highly elastic poly(l-lactide-co-ε-caprolactone) (PLC) via a melt-drawing method. The morphology, crystallinity, thermal and mechanical properties of the PLC fibers were investigated. They were highly aligned and have a uniform diameter. PLC is found to be semicrystalline consisting of α- and β- lactide (LA) crystals. The crystallinity increases up to 16.8% with increasing melt-drawing speeds due to strain-induced crystallization. Modulus and strength increases while ductility decreases with an increase in crystallinity of the PLC samples. Moisture will not degrade the overall tensile properties but affect its tangent modulus at the low strain. L929 cells are able to attach and proliferate on the scaffolds very well. The cells seeded on the scaffolds show normal morphology with >90% cell viability after 6 days of culture. These results demonstrate that the PLC fibrous scaffold has good potential for use in esophageal tissue engineering application. PMID:26735183

  2. Reverse Engineering Applied to Red Human Hair Pheomelanin Reveals Redox-Buffering as a Pro-Oxidant Mechanism.

    PubMed

    Kim, Eunkyoung; Panzella, Lucia; Micillo, Raffaella; Bentley, William E; Napolitano, Alessandra; Payne, Gregory F

    2015-01-01

    Pheomelanin has been implicated in the increased susceptibility to UV-induced melanoma for people with light skin and red hair. Recent studies identified a UV-independent pathway to melanoma carcinogenesis and implicated pheomelanin's pro-oxidant properties that act through the generation of reactive oxygen species and/or the depletion of cellular antioxidants. Here, we applied an electrochemically-based reverse engineering methodology to compare the redox properties of human hair pheomelanin with model synthetic pigments and natural eumelanin. This methodology exposes the insoluble melanin samples to complex potential (voltage) inputs and measures output response characteristics to assess redox activities. The results demonstrate that both eumelanin and pheomelanin are redox-active, they can rapidly (sec-min) and repeatedly redox-cycle between oxidized and reduced states, and pheomelanin possesses a more oxidative redox potential. This study suggests that pheomelanin's redox-based pro-oxidant activity may contribute to sustaining a chronic oxidative stress condition through a redox-buffering mechanism. PMID:26669666

  3. An engineered genetic selection for ternary protein complexes inspired by a natural three-component hitchhiker mechanism

    PubMed Central

    Lee, Hyeon-Cheol; Portnoff, Alyse D.; Rocco, Mark A.; DeLisa, Matthew P.

    2014-01-01

    The bacterial twin-arginine translocation (Tat) pathway is well known to translocate correctly folded monomeric and dimeric proteins across the tightly sealed cytoplasmic membrane. We identified a naturally occurring heterotrimer, the Escherichia coli aldehyde oxidoreductase PaoABC, that is co-translocated by the Tat translocase according to a ternary “hitchhiker” mechanism. Specifically, the PaoB and PaoC subunits, each devoid of export signals, are escorted to the periplasm in a piggyback fashion by the Tat signal peptide-containing subunit PaoA. Moreover, export of PaoA was blocked when either PaoB or PaoC was absent, revealing a surprising interdependence for export that is not seen for classical secretory proteins. Inspired by this observation, we created a bacterial three-hybrid selection system that links the formation of ternary protein complexes with antibiotic resistance. As proof-of-concept, a bispecific antibody was employed as an adaptor that physically crosslinked one antigen fused to a Tat export signal with a second antigen fused to TEM-1 β-lactamase (Bla). The resulting non-covalent heterotrimer was exported in a Tat-dependent manner, delivering Bla to the periplasm where it hydrolyzed β-lactam antibiotics. Collectively, these results highlight the remarkable flexibility of the Tat system and its potential for studying and engineering ternary protein interactions in living bacteria. PMID:25531212

  4. TRISO-fuel element thermo-mechanical performance modeling for the hybrid LIFE engine with Pu fuel blanket

    NASA Astrophysics Data System (ADS)

    DeMange, P.; Marian, J.; Caro, M.; Caro, A.

    2010-10-01

    A TRISO-coated fuel thermo-mechanical performance study is performed for the fusion-fission hybrid Laser Inertial Fusion Engine (LIFE) to test the viability of TRISO particles to achieve ultra-high burn-up of Pu or transuranic spent nuclear fuel blankets. Our methodology includes full elastic anisotropy, time and temperature varying material properties, and multilayer capabilities. In order to achieve fast fluences up to 30 × 10 25 n m -2 ( E > 0.18 MeV), judicious extrapolations across several orders of magnitude of existing material databases have been carried out. The results of our study indicate that failure of the pyrolytic carbon (PyC) layers occurs within the first 2 years of operation. The particles then behave as a single-SiC-layer particle and the SiC layer maintains reasonably-low tensile stresses until the end-of-life. It is also found that the PyC creep constant, K, has a striking influence on the fuel performance of TRISO-coated particles, whose stresses scale almost inversely proportional to K. Conversely, varying the geometry of the TRISO-coated fuel particles results in little differences in terms of fuel performance.

  5. Reverse Engineering Applied to Red Human Hair Pheomelanin Reveals Redox-Buffering as a Pro-Oxidant Mechanism

    PubMed Central

    Kim, Eunkyoung; Panzella, Lucia; Micillo, Raffaella; Bentley, William E.; Napolitano, Alessandra; Payne, Gregory F.

    2015-01-01

    Pheomelanin has been implicated in the increased susceptibility to UV-induced melanoma for people with light skin and red hair. Recent studies identified a UV-independent pathway to melanoma carcinogenesis and implicated pheomelanin’s pro-oxidant properties that act through the generation of reactive oxygen species and/or the depletion of cellular antioxidants. Here, we applied an electrochemically-based reverse engineering methodology to compare the redox properties of human hair pheomelanin with model synthetic pigments and natural eumelanin. This methodology exposes the insoluble melanin samples to complex potential (voltage) inputs and measures output response characteristics to assess redox activities. The results demonstrate that both eumelanin and pheomelanin are redox-active, they can rapidly (sec-min) and repeatedly redox-cycle between oxidized and reduced states, and pheomelanin possesses a more oxidative redox potential. This study suggests that pheomelanin’s redox-based pro-oxidant activity may contribute to sustaining a chronic oxidative stress condition through a redox-buffering mechanism. PMID:26669666

  6. Engineered redox-responsive PEG detachment mechanism in PEGylated nano-graphene oxide for intracellular drug delivery.

    PubMed

    Wen, Huiyun; Dong, Chunyan; Dong, Haiqing; Shen, Aijun; Xia, Wenjuan; Cai, Xiaojun; Song, Yanyan; Li, Xuequan; Li, Yongyong; Shi, Donglu

    2012-03-12

    In biomedical applications, polyethylene glycol (PEG) functionalization has been a major approach to modify nanocarriers such as nano-graphene oxide for particular biological requirements. However, incorporation of a PEG shell poses a significant diffusion barrier that adversely affects the release of the loaded drugs. This study addresses this critical issue by employing a redox-responsive PEG detachment mechanism. A PEGylated nano-graphene oxide (NGO-SS-mPEG) with redox-responsive detachable PEG shell is developed that can rapidly release an encapsulated payload at tumor-relevant glutathione (GSH) levels. The PEG shell grafted onto NGO sheets gives the nanocomposite high physiological solubility and stability in circulation. It can selectively detach from NGO upon intracellular GSH stimulation. The surface-engineered structures are shown to accelerate the release of doxorubicin hydrochloride (DXR) from NGO-SS-mPEG 1.55 times faster than in the absence of GSH. Confocal microscopy shows clear evidence of NGO-SS-mPEG endocytosis in HeLa cells, mainly accumulated in cytoplasm. Furthermore, upon internalization of DXR-loaded NGO with a disulfide-linked PEG shell into HeLa cells, DXR is effectively released in the presence of an elevated GSH reducing environment, as observed in confocal microscopy and flow cytometric experiments. Importantly, inhibition of cell proliferation is directly correlated with increased intracellular GSH concentrations due to rapid DXR release. PMID:22228696

  7. Student Autonomy and its Effects on Student Enjoyment in a Traditional Mechanics Course for First-Year Engineering Students

    NASA Astrophysics Data System (ADS)

    Perera, Janaki I.; Quinlivan, Brendan T.; Simonovich, Jennifer A.; Towers, Emily; Zadik, Oren H.; Zastavker, Yevgeniya V.

    2012-02-01

    In light of recent literature in educational psychology, this study investigates instructional support and students' autonomy at a small technical undergraduate school. Grounded theory is used to analyze twelve semi-structured open-ended interviews about engineering students' experiences in Introductory Mechanics that includes Lecture, Recitation, and Laboratory components. Using data triangulation with each course component as a unit of analysis, this study examines students' course enjoyment as a function of instructional support and autonomy. The Lecture utilizes traditional instructor-centered pedagogy with predominantly passive learning and no student autonomy. The Recitation creates an active learning environment through small group work with a moderate degree of autonomy. The Laboratory is designed around self-guided project-based activities with significant autonomy. Despite these differences, all three course components provide similar levels of instructional support. The data reveal that students enjoy the low autonomy provided by Lecture and Recitations while finding the Laboratory frustrating. Analyses indicate that the differences in autonomy contribute to students' misinterpretation of the three course components' value within the context of the entire course.

  8. Thermo-mechanical and neutron lifetime modeling and design of Be pebbles in the neutron multiplier for the LIFE engine

    SciTech Connect

    DeMange, P; Marian, J; de Caro, M S; Caro, A

    2009-03-16

    Concept designs for the laser-initiated fusion/fission engine (LIFE) include a neutron multiplication blanket containing Be pebbles flowing in a molten salt coolant. These pebbles must be designed to withstand the extreme irradiation and temperature conditions in the blanket to enable a safe and cost-effective operation of LIFE. In this work, we develop design criteria for spherical Be pebbles on the basis of their thermomechanical behavior under continued neutron exposure. We consider the effects of high fluence/fast flux on the elastic, thermal and mechanical properties of nuclear-grade Be. Our results suggest a maximum pebble diameter of 30 mm to avoid tensile failure, coated with an anti-corrosive, high-strength metallic shell to avoid failure by pebble contact. Moreover, we find that the operation temperature must always be kept above 450 C to enable creep to relax the stresses induced by swelling, which we estimate to be at least 16 months if uncoated and up to six years when coated. We identify the sources of uncertainty on the properties used and discuss the advantages of new intermetallic beryllides and their use in LIFE's neutron multiplier. To establish Be-pebble lifetimes with improved confidence, reliable experiments to measure irradiation creep must be performed.

  9. Design, construction and mechanical testing of digital 3D anatomical data-based PCL-HA bone tissue engineering scaffold.

    PubMed

    Yao, Qingqiang; Wei, Bo; Guo, Yang; Jin, Chengzhe; Du, Xiaotao; Yan, Chao; Yan, Junwei; Hu, Wenhao; Xu, Yan; Zhou, Zhi; Wang, Yijin; Wang, Liming

    2015-01-01

    The study aims to investigate the techniques of design and construction of CT 3D reconstructional data-based polycaprolactone (PCL)-hydroxyapatite (HA) scaffold. Femoral and lumbar spinal specimens of eight male New Zealand white rabbits were performed CT and laser scanning data-based 3D printing scaffold processing using PCL-HA powder. Each group was performed eight scaffolds. The CAD-based 3D printed porous cylindrical stents were 16 piece × 3 groups, including the orthogonal scaffold, the Pozi-hole scaffold and the triangular hole scaffold. The gross forms, fiber scaffold diameters and porosities of the scaffolds were measured, and the mechanical testing was performed towards eight pieces of the three kinds of cylindrical scaffolds, respectively. The loading force, deformation, maximum-affordable pressure and deformation value were recorded. The pore-connection rate of each scaffold was 100 % within each group, there was no significant difference in the gross parameters and micro-structural parameters of each scaffold when compared with the design values (P > 0.05). There was no significant difference in the loading force, deformation and deformation value under the maximum-affordable pressure of the three different cylinder scaffolds when the load was above 320 N. The combination of CT and CAD reverse technology could accomplish the design and manufacturing of complex bone tissue engineering scaffolds, with no significant difference in the impacts of the microstructures towards the physical properties of different porous scaffolds under large load. PMID:25596860

  10. Development of an eight-step kinetics mechanism for propane and its application in a transient, thin gap, engine model

    SciTech Connect

    Kiehne, T.M.

    1985-01-01

    An accurate eight-step kinetics mechanism for the oxidation of propane, based on previous research, was developed in ignition delay studies and investigations of freely propagating and quenching flames. Results from a detailed kinetics model and available experimental data were used for comparison and verification. One-dimensional transient calculations were performed at pressures ranging from one to 40 atmospheres, unburned gas temperatures from 400 to 500 K, and near stoichiometric equivalence ratios. The detailed kinetics results confirm the existence of extensive post-quench burnup of propane after the time of flame-arrival at the wall. However, the range of calculations at engine-like conditions using a higher molecular weight fuel than used in previous studies indicates that hydrocarbons other than the fuel contribute significantly to the total of all unburned hydrocarbons in the wall quench layer. Based on the detailed kinetics results, an eight-step kinetics model developed from experiment is shown to be deficient in certain key areas. Therefore, it is modified to improve representation of the induction region, flame speed, postflame region, wall quench behavior, and unburned hydrocarbon evolution. Correlations that extend the model to a wider pressure range and fuel-rich equivalence ratios are developed.

  11. HEALTH SECTOR ASSESSMENT

    EPA Science Inventory

    As part of the USGCRP's First National Assessment effort, EPA's Global Change Research Program sponsored the Health Sector Assessment. The Health Sector Assessment was co-chaired by Dr. Jonathan A. Patz, Director of the Program on the Health Effects of Global Environmental Change...

  12. Advanced Prop-fan Engine Technology (APET) single- and counter-rotation gearbox/pitch change mechanism

    NASA Technical Reports Server (NTRS)

    Reynolds, C. N.

    1985-01-01

    The preliminary design of advanced technology (1992) prop-fan engines for single-rotation prop-fans, the conceptual design of the entire propulsion system, and an aircraft evaluation of the resultant designs are discussed. Four engine configurations were examined. A two-spool engine with all axial compressors and a three-spool engine with axial/centrifugal compressors were selected. Integrated propulsion systems were designed in conjunction with airframe manufacturers. The design efforts resulted in 12,000 shaft horsepower engines installed in over the installations with in-line and offset gearboxes. The prop-fan powered aircraft used 21 percent less fuel and cost 10 percent less to operate than a similar aircraft powered by turbofan engines with comparable technology.

  13. A Quantitative Analysis of Students' Perception of Generic Skills within an Undergraduate Electronics/mechanical Engineering Curriculum

    ERIC Educational Resources Information Center

    Duggan, Louise

    2014-01-01

    Generic skills are considered as key essential skills which are required by all individuals in the engineering profession and are considered vital for success. Integrating generic skills into engineering education is a key concern for universities and colleges involved in delivering such courses. The accreditation criteria for engineering…

  14. Construction Mechanic, Engine Tune-Up I, 8-7. 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 course, adapted from military curriculum materials for use in vocational and technical education, teaches students to perform a complete engine tune-up using appropriate hand tools, special tools, and testing equipment. Students completing the course will be able to diagnose gasoline-engine performance and perform corrective measures to…

  15. Teaching Design in the First Years of a Traditional Mechanical Engineering Degree: Methods, Issues and Future Perspectives

    ERIC Educational Resources Information Center

    Silva, Arlindo; Fontul, Mihail; Henriques, Elsa

    2015-01-01

    Engineering design is known as an answer to an ill-defined problem. As any answer to an ill-defined problem, it can never be completely right or absolutely wrong. The methods that universities use to teach engineering design, as a consequence of this, suffer from the same fate. However, the accumulated experience with the "chalk and…

  16. Construction Mechanic, Engine Tune-Up II (Diesel), 8-8. 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 course, adapted from military curriculum materials for vocational and technical education, teaches students to restore diesel engine performance to the manufacturer's specifications through troubleshooting and analyzing diesel engine fuel systems and to make minor and major adjustments to those components that directly affect engine…

  17. Control of electrical transport mechanisms at metal-zinc oxide interfaces by subsurface defect engineering with remote plasma treatment

    NASA Astrophysics Data System (ADS)

    Mosbacker, Howard Lee, IV

    ZnO has received renewed attention in recent years due its exciting properties as a wide band gap semiconductor. ZnO has several advantages over GaN including the availability of substrates, a room temperature excitonic emission, and an environmentally benign chemistry. ZnO applications include efficient blue light emitters, surface acoustic wave devices, transparent conductors, high power transistors, and solid state white lighting. Despite this versatility, several hurdles remain before device realization. Firstly, ZnO is almost always p-type. Although high quality n-type ZnO is abundant, there is no stable and reliable p-type doping scheme. Secondly, research into high quality Ohmic and Schottky contacts has been limited. Although there is an abundance of literature, there has yet to be an attempt to understand the physical and chemical mechanisms at metal- ZnO interfaces. In this work, plasma processing techniques are adopted to ZnO. These cold plasmas allow for room temperature modification of the subsurface. Implanting hydrogen has identified it as a primary n-type dopant responsible for a large fraction of the n-type conductivity. Oxygen plasma treatment has yielded an Ohmic to Schottky conversion by reducing oxygen defects at the near surface. Deposition of metals on clean and ordered surfaces reveal the importance that defects play at the metal-semiconductor interface. Higher concentrations of defects promote reactions. This increased reaction eutectic forming and oxide forming. Understanding the nature of the metal allows for engineering of high quality blocking contacts. These contacts can provide added thermal stability to devices. Subsurface introduction of hydrogen and nitrogen provide a potential roadmap to p-type doping and high quality Schottky contacts. Overall, control of transport properties and contact integrity is achieved by remote plasma processing.

  18. High seeding density of human chondrocytes in agarose produces tissue-engineered cartilage approaching native mechanical and biochemical properties.

    PubMed

    Cigan, Alexander D; Roach, Brendan L; Nims, Robert J; Tan, Andrea R; Albro, Michael B; Stoker, Aaron M; Cook, James L; Vunjak-Novakovic, Gordana; Hung, Clark T; Ateshian, Gerard A

    2016-06-14

    Animal cells have served as highly controllable model systems for furthering cartilage tissue engineering practices in pursuit of treating osteoarthritis. Although successful strategies for animal cells must ultimately be adapted to human cells to be clinically relevant, human chondrocytes are rarely employed in such studies. In this study, we evaluated the applicability of culture techniques established for juvenile bovine and adult canine chondrocytes to human chondrocytes obtained from fresh or expired osteochondral allografts. Human chondrocytes were expanded and encapsulated in 2% agarose scaffolds measuring ∅3-4mm×2.3mm, with cell seeding densities ranging from 15 to 90×10(6)cells/mL. Subsets of constructs were subjected to transient or sustained TGF-β treatment, or provided channels to enhance nutrient transport. Human cartilaginous constructs physically resembled native human cartilage, and reached compressive Young's moduli of up to ~250kPa (corresponding to the low end of ranges reported for native knee cartilage), dynamic moduli of ~950kPa (0.01Hz), and contained 5.7% wet weight (%/ww) of glycosaminoglycans (≥ native levels) and 1.5%/ww collagen. We found that the initial seeding density had pronounced effects on tissue outcomes, with high cell seeding densities significantly increasing nearly all measured properties. Transient TGF-β treatment was ineffective for adult human cells, and tissue construct properties plateaued or declined beyond 28 days of culture. Finally, nutrient channels improved construct mechanical properties, presumably due to enhanced rates of mass transport. These results demonstrate that our previously established culture system can be successfully translated to human chondrocytes. PMID:27198889

  19. Start Up Research Effort in Fluid Mechanics. Advanced Methods for Acoustic and Thrust Benefits for Aircraft Engine Nozzle

    NASA Technical Reports Server (NTRS)

    White, Samuel G.; Gilinsky, Mikhail M.

    1997-01-01

    In accordance with the project plan for the report period in the proposal titled above, HU and FML teams investigated two sets of concepts for reduction of noise and improvement in efficiency for jet exhaust nozzles of aircraft engines and screws for mixers, fans, propellers and boats. The main achievements in the report period are: (a) Publication of the paper in the AIAA Journal, which described our concepts and some results. (b) The Award in the Civil Research and Development Foundation (CRDF) competition. This 2 year grant for Hampton University (HU) and Central AeroHydrodynamic Institute (TSAGI, Moscow, Russia) supports the research implementation under the current NASA FAR grant. (c) Selection for funding by NASA HQ review panel of the Partnership Awards Concept Paper. This two year grant also will support our current FAR grant. (d) Publication of a Mobius Strip concept in NASA Technical Briefs, June, 1996, and a great interest of many industrial companies in this invention. Successful experimental results with the Mobius shaped screw for mixers, which save more than 30% of the electric power by comparison with the standard screws. Creation of the scientific-popular video-film which can be used for commercial and educational purposes. (e) Organization work, joint meetings and discussions of the NASA LARC JNL Team and HU professors and administration for the solution of actual problems and effective work of the Fluid Mechanics Laboratory at Hampton University. In this report the main designs are enumerated. It also contains for both concept sets: (1) the statement of the problem for each design, some results, publications, inventions, patents, our vision for continuation of this research, and (2) present and expected problems in the future.

  20. Wear mechanism and wear prevention in coal-fueled diesel engines. Task 3, Traditional approaches to wear prevention

    SciTech Connect

    Schwalb, J.A.

    1991-06-01

    Contamination of the lube-oil with hard abrasive particles leads to a three-body abrasive wear mechanism that highly accelerates piston ring/cylinder liner wear in coal-fueled diesel engines. One approach to reducing that wear is to modify the size and orientation of surface asperities on the cylinder to enhance the formation of a hydrodynamic film, and to provide avenues of escape for particles that would otherwise be trapped in the wear zone. Another approach is to introduce additives into the contaminated lube-oil that further enhance hydrodynamic film formation, form chemical films on the wearing surfaces, or form films on the contaminant particles. This work focuses on defining the effects of cylinder liner surface finish, various configurations of slots in the cylinder liner surface, and various additives in the contaminated lube-oil on the wear process. Wear tests were initiated in a bench apparatus using coal-ash contaminated lube-oil to test the various wear configurations. The results of these tests indicate that the formation of a hydrodynamic film between the ring and cylinder specimens is enhanced by increasing surface roughness, and by orienting the surface asperities normal to the direction of ring travel but modifications to the cylinder liner surface did not greatly reduce the wear rate. Additives to the lubricant seemed to have a much more significant effect on wear, with a dispersant additive highly accelerating the wear, while a detergent additive was able to reduce the wear almost to the rate achieved where there was no contaminant.