Note: This page contains sample records for the topic mechanics fluids engineering from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Early Work on Fluid Mechanics in The IC Engine  

NASA Astrophysics Data System (ADS)

Early work of Ricardo is described, in which squish is used in flat-head engines to generate turbulence levels comparable to those in overhead-valve engines, leading to rapid flame propagation, and suppressing knock. Work by NACA before World War II is described, in which turbulence levels were measured in overhead-valve engines, indicating indirectly that surprisingly high levels were achieved just before ignition, possibly due to a tumble instability. Finally, work of Obukhov of 30 years ago is described, in which instabilities of tumbling flow are investigated in ellipsoids crudely modeling the engine cylinder as the piston rises; this suggests that there is an instability leading to intense small-scale motion just before ignition. Suggestions for further work are given.

Lumley, John L.

2

Exploring the essence of productive pedagogy in Fluid Mechanics and Material and process curricula for second year Engineering  

Microsoft Academic Search

A Curriculum development in the fluid mechanics and material and processes subjects for foundation levels for the engineering students at university level has been assessed against the requirements of engineering education productive pedagogy in the new era. Four corners are essential for productive pedagogy namely Intellectual quality, Connectedness, Supportive learning environment and Recognition of difference. These are checked against the

A. Elgezawy

3

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.

4

Mechanics of granular-frictional-visco-plastic fluids in civil and mining engineering  

NASA Astrophysics Data System (ADS)

The shear stress generated in mine backfill slurries and fresh concrete contains both velocity gradient dependent and frictional terms, categorised as frictional viscous plastic fluids. This paper discusses application of the developed analytical solution for flow rate as a function of pressure and pressure gradient in discs, pipes and cones for such frictional Bingham-Herschel-Bulkley fluids. This paper discusses application of this continuum fluid model to industrial materials like mine and mineral slurries, backfills and fresh concrete tests.

Alehossein, H.; Qin, Z.

2013-10-01

5

Fluid mechanics of combustion systems; Proceedings of the Fluids Engineering Conference, Boulder, CO, June 22, 23, 1981  

NASA Astrophysics Data System (ADS)

The work examines such topics as the parametric variations of a heat balanced engine, the calculation of pulverized coal combustion in an axisymmetrical furnace, optical tomography for diagnostics in combusting flows, the numerical simulation of swirling flow in a cyclone chamber, and the flow aerodynamics modeling of an MHD swirl combustor. Consideration is also given to the interaction between strain fields and flames in spark ignition engines, the flow and combustion characteristics of turbulent reacting flames, the application of numerical modeling to gas turbine combustor development problems, and the prediction of swirling flow fields in axisymmetric combustor geometries.

Morel, T.; Lohmann, R. P.; Rackley, J. M.

1981-01-01

6

Quantitative, single shot, two-dimensional spontaneous Raman measurements for fluid mechanics and engine applications  

Microsoft Academic Search

Spontaneous Raman Scattering was used for quantitative, two-dimensional, single-shot measurements of species concentration in optically accessible confinements and in an experimental single-cylinder internal combustion engine. The study comprised three parts. In the first part, the technique was used for methane concentration measurements in a laminar jet issuing into compressed nitrogen (10 bar, 293 K). The injection Reynolds number was 550.

Dimitrios Constantinou Kyritsis

1998-01-01

7

Quantitative, single shot, two-dimensional spontaneous Raman measurements for fluid mechanics and engine applications  

NASA Astrophysics Data System (ADS)

Spontaneous Raman Scattering was used for quantitative, two-dimensional, single-shot measurements of species concentration in optically accessible confinements and in an experimental single-cylinder internal combustion engine. The study comprised three parts. In the first part, the technique was used for methane concentration measurements in a laminar jet issuing into compressed nitrogen (10 bar, 293 K). The injection Reynolds number was 550. Initial results showed unexpected structures in the acquired concentration profiles. Thus, the steadiness of the laminar flow was confirmed with high speed shadowgraph movies and laser induced fluorescence measurements. Eventually, it was proven that the structures were due to characteristics of the camera system. A technique was then devised for the proper acquisition and processing of data and spatial resolution of 500 mum was achieved. Methane number density equal to 12% of the number density of pure methane (0.247E+26 molecules/msp3) was then measured with a signal-to-noise ratio of approximately 3. The measurements were compared with the results of direct numerical simulation of the flow field. In the second part, measurements in a laminar hydrogen jet were taken. Because of the reduced Raman signal of hydrogen, the incident laser power was increased by installing the pressurized chamber within the laser cavity. This yielded an increase in power by a factor of 2.5. For the measurement of the laser sheet intensity in the laser cavity, insertion of a fluorescent dye cell and Rayleigh scattering were used and evaluated comparatively. The precise location of the waist of the laser sheet was determined by trial and error. The spatial resolution of the measurements was 650 mum and a number density of 0.371E+26 hydrogen molecules/msp3 was measured with a signal-to-noise ratio of 3. The measurements were again compared with results of direct numerical simulation. In the third part, the feasibility of two-dimensional single-shot Spontaneous Raman measurements in an engine cylinder was established. Measurements of methane concentration after direct injection in the cylinder of an experimental single-cylinder engine were taken. The engine was not fired to avoid laser induced incandescence interference. The spatial resolution was limited to 800 mum by the thickness of the laser sheet. Fast mixing of the methane jet was documented but a precise evaluation of the equivalence ratio was beyond the resolution of this first attempt. Finally, existing hardware for data acquisition and algorithms for two dimensional data reduction were reviewed and recommendations were made for the extraction of quantitative information from two-dimensional, single-shot Spontaneous Raman signals which are weak and noisy.

Kyritsis, Dimitrios Constantinou

8

Mechanical Engineering Course  

Microsoft Academic Search

Carnegie Mellon University offers a first-year course titled Funda- mentals of Mechanical Engineering to introduce undergraduate students to the discipline of mechanical engineering. The goals of the course are to excite students about the field of mechanical engi- neering early in their careers, introduce basic mechanical engineer- ing concepts in an integrated way, provide a link to the basic physics

SUSAN A. AMBROSE; CRISTINA H. AMON

9

Pressurized-fluid-operated engine  

SciTech Connect

This patent describes a pressurized-fluid-operated reciprocating engine for providing output power by use of a pressurized gas that expands within the engine without combustion. It comprises: an engine block having a plurality of cylinders within which respective pistons are reciprocatable to provide a rotary power output; gas inlet means connected with the engine block for introducing a pressurized gas into the respective cylinders in a predetermined, timed relationship to provide a smooth power output from the engine; gas outlet means connected with the engine block for conveying exhaust gas from the respective cylinders after the gas expanded to move the pistons within the cylinders; and recirculation means extending between the inlet means and the outlet means for recirculation a predetermined quantity of exhaust gas. The recirculation means including ejector means for drawing exhaust gas into the recirculation means.

Holleyman, J.E.

1990-01-30

10

Perspectives in Fluid Mechanics  

Microsoft Academic Search

Distinguished authors discuss topics in physical oceanography, transonic aerodynamics, dynamics of vorticity, numerical simulation of turbulent flows, astrophysical jets, strange attractors, human-powered flight, and the fluid mechanics of the Old Faithful geyser and of the Mount St. Helens eruption of 1980. The authors deal with specific problems, but the emphasis is usually on the way that research is carried out

Donald Coles

1988-01-01

11

Relativistic viscoelastic fluid mechanics  

SciTech Connect

A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.

Fukuma, Masafumi; Sakatani, Yuho [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

2011-08-15

12

Applied Fluid Mechanics. Lecture Notes.  

ERIC Educational Resources Information Center

|This set of lecture notes is used as a supplemental text for the teaching of fluid dynamics, as one component of a thermodynamics course for engineering technologists. The major text for the course covered basic fluids concepts such as pressure, mass flow, and specific weight. The objective of this document was to present additional fluids

Gregg, Newton D.

13

Selected topics of fluid mechanics  

USGS Publications Warehouse

The fundamental equations of fluid mechanics are specific expressions of the principles of motion which are ascribed to Isaac Newton. Thus, the equations which form the framework of applied fluid mechanics or hydraulics are, in addition to the equation of continuity, the Newtonian equations of energy and momentum. These basic relationships are also the foundations of river hydraulics. The fundamental equations are developed in this report with sufficient rigor to support critical examinations of their applicability to most problems met by hydraulic engineers of the Water Resources Division of the United States Geological Survey. Physical concepts are emphasized, and mathematical procedures are the simplest consistent with the specific requirements of the derivations. In lieu of numerical examples, analogies, and alternative procedures, this treatment stresses a brief methodical exposition of the essential principles. An important objective of this report is to prepare the user to read the literature of the science. Thus, it begins With a basic vocabulary of technical symbols, terms, and concepts. Throughout, emphasis is placed on the language of modern fluid mechanics as it pertains to hydraulic engineering. The basic differential and integral equations of simple fluid motion are derived, and these equations are, in turn, used to describe the essential characteristics of hydrostatics and piezometry. The one-dimensional equations of continuity and motion are defined and are used to derive the general discharge equation. The flow net is described as a means of demonstrating significant characteristics of two-dimensional irrotational flow patterns. A typical flow net is examined in detail. The influence of fluid viscosity is described as an obstacle to the derivation of general, integral equations of motion. It is observed that the part played by viscosity is one which is usually dependent on experimental evaluation. It follows that the dimensionless ratios known as the Euler, Froude, Reynolds, Weber, and Cauchy numbers are defined as essential tools for interpreting and using experimental data. The derivations of the energy and momentum equations are treated in detail. One-dimensional equations for steady nonuniform flow are developed, and the restrictions applicable to the equations are emphasized. Conditions of uniform and gradually varied flow are discussed, and the origin of the Chezy equation is examined in relation to both the energy and the momentum equations. The inadequacy of all uniform-flow equations as a means of describing gradually varied flow is explained. Thus, one of the definitive problems of river hydraulics is analyzed in the light of present knowledge. This report is the outgrowth of a series of short schools conducted during the spring and summer of 1953 for engineers of the Surface Water Branch, Water Resources Division, U. S. Geological Survey. The topics considered are essentially the same as the topics selected for inclusion in the schools. However, in order that they might serve better as a guide and outline for informal study, the arrangement of the writer's original lecture notes has been considerably altered. The purpose of the report, like the purpose of the schools which inspired it, is to build a simple but strong framework of the fundamentals of fluid mechanics. It is believed that this framework is capable of supporting a detailed analysis of most of the practical problems met by the engineers of the Geological Survey. It is hoped that the least accomplishment of this work will be to inspire the reader with the confidence and desire to read more of the recent and current technical literature of modern fluid mechanics.

Kindsvater, Carl E.

1958-01-01

14

Basic Engineer Equipment Mechanic.  

ERIC Educational Resources Information Center

|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…

Marine Corps Inst., Washington, DC.

15

On the fluid mechanics of fires  

SciTech Connect

Fluid mechanics research related to fire is reviewed with focus on canonical flows, multiphysics coupling aspects, experimental and numerical techniques. Fire is a low-speed, chemically-reacting, flow in which buoyancy plans an important role. Fire research has focused on two canonical flows, the reacting boundary-layer and the reacting free plume. There is rich, multi-lateral, bi-directional, coupling among fluid mechanics and scalar transport, combustion, and radiation. There is only a limited experimental fluid-mechanics database for fire due to measurement difficulties in the harsh environment, and the focus within the fire community on thermal/chemical consequences. Increasingly, computational fluid dynamics techniques are being used to provide engineering guidance on thermal/chemical consequences and to study fire phenomenology.

TIESZEN,SHELDON R.

2000-02-29

16

Stirling engine performance optimization with different working fluids  

Microsoft Academic Search

The design flexibility of Stirling cycle devices is evident from the wide variety of mechanical configurations that have been developed as well as the many differing applications that have been shown to be technically feasible. The choice of working fluid is one option that strongly influences engine design. Hydrogen permits the most compact engine (for a given power output and

J. G. Daley; W. W. Marr; T. J. Heames

1986-01-01

17

FLUID MECHANICS AND HOMELAND SECURITY  

Microsoft Academic Search

Homeland security involves many applications of fluid mechanics and offers many opportunities for research and development. This review explores a wide selection of fluids topics in counterterrorism and suggests future directions. Broad topics range from preparedness and deterrence of impending terrorist attacks to detection, re- sponse, and recovery. Specific topics include aircraft hardening, blast mitigation, sensors and sampling, explosive detection,

Gary S. Settles

2006-01-01

18

Finite approximations in fluid mechanics  

Microsoft Academic Search

This book contains twenty papers on work which was conducted between 1983 and 1985 in the Priority Research Program ''Finite Approximations in Fluid Mechanics'' of the German Research Society (Deutsche Forschungsgemeinschaft). Scientists from numerical mathematics, fluid mechanics, and aerodynamics present their research on boundary-element methods, factorization methods, higher-order panel methods, multigrid methods for elliptical and parabolic problems, two-step schemes for

Hirschel

1986-01-01

19

Engine & Vehicle Mechanics Curriculum.  

ERIC Educational Resources Information Center

|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…

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

20

Numerical methods for fluid transient analysis; Proceedings of the Applied Mechanics, Bioengineering, and Fluids Engineering Conference, Houston, TX, June 20-22, 1983  

Microsoft Academic Search

Among the topics discussed are implicit methods for the solution of the one-dimensional wave equation, second-order explicit methods for transient flow analysis, a generalized implicit finite difference method for transient analysis of compressible and incompressible fluid flows, the modeling of transient two-component flow with a four-point implicit method, one-dimensional transient gas flow with internal heating, transient pressure wave radial and

C. S. Martin; M. H. Chaudhry

1983-01-01

21

Spreadsheet Fluid Dynamics in Aerospace Engineering  

Microsoft Academic Search

Spreadsheets are now widely used in engineering and scientific fields to solve numerical, analytical, and experimental problems. The present authors tried to extend the Spreadsheet Fluid Dynamics, i.e., SFD, to aerospace engineering problems. Spreadsheets enable us to present the analytical solutions in graphical forms easily. The matrix inverse function makes it possible to solve the aerodynamic panel methods and the

Etsuo MORISHITA; Hisao KOYAMA; Takeo OKUNUKI; Hiroyoshi ASANO; Yoshihiro FUJIMAKI; Kazuo NAKAMURA; Shingo TARAO

22

Supercritical fluid technologies and tissue engineering scaffolds  

Microsoft Academic Search

Supercritical fluid (SCF) processing methods possess advantages over standard processing methods for the production of scaffolds for use in tissue engineering. Advantages include the absence of organic solvents, the ability to incorporate delicate biologicals without loss of activity, and control over the morphology of an internal porous architecture. This review describes SCF processing methods of relevance to tissue engineering and

Robin A. Quirk; Richard M. France; Kevin M. Shakesheff; Steven M. Howdle

2004-01-01

23

The 1991 research program (of the Faculty of Mechanical Engineering)  

NASA Astrophysics Data System (ADS)

The main research activities and programs are overviewed. The following domains are covered: production techniques, production organization, transportation and storage, mechanical engineering automation, design and construction, ergonomics, design in plastics, thermal mechanics, heat transfer and fluid mechanics, biomedical mechanical engineering, materials science, and technical mechanics and tribology.

1991-05-01

24

Respiratory Fluid Mechanics  

NASA Astrophysics Data System (ADS)

This brief overview of our groups activities includes liquid plug propagation in single and bifurcating tubes, a subject which pertains to surfactant delivery, liquid ventilation, pulmonary edema, and drowning. As the plug propagates, a variety of flow patterns may emerge depending on the parameters. It splits unevenly at airway bifurcations and can rupture, which reopens the airway to gas flow. Both propagation and rupture may damage the underlying airway wall cells. Another topic is surfactant dynamics and flow in a model of an oscillating alveolus. The analysis shows a nontrivial cycle-averaged surfactant concentration gradient along the interface that generates steady streaming. The steady streaming patterns particularly depend on the ratio of inspiration to expiration time periods and the sorption parameter. Vortices, single and multiple, may be achieved, as well as a saddle point configuration. Potential applications are pulmonary drug administration, cell-cell signaling pathways, and gene therapy. Finally, capillary instabilities which cause airway closure, and strategies for stabilization, will be presented. This involves the core-annular flow of a liquid-lined tube, where the core (air) is forced to oscillate axially. The stabilization mechanism is similar to that of a reversing butter knife, where the core shear wipes the growing liquid bulge, from the Rayleigh instability, back on to the tube wall during the main tidal volume stroke, but allows it to grow back as the stroke and shear turn around.

Grotberg, James

2005-11-01

25

Numerical methods for fluid transient analysis. Proceedings of the applied mechanics, bioengineering, and fluids engineering conference, Houston, TX, June 20-22, 1983  

SciTech Connect

Among the topics discussed are implicit methods for the solution of the one-dimensional wave equation, second-order explicit methods for transient flow analysis, a generalized implicit finite difference method for transient analysis of compressible and incompressible fluid flows, the modeling of transient two-component flow with a four-point implicit method, one-dimensional transient gas flow with internal heating, transient pressure wave radial and axial variations, and vaporous and gaseous cavitation simulation. Also discussed are variable celerity modeling by the method of characteristics, a numerical model for transients in petroleum product pipelines, solid-liquid-gas mixture one-dimensional transient flows, hydraulic transients in tunnels with concurrent open channel and pressurized flow, and waterhammer transient control with dynamic programming of valve stoking. For individual items see A84-13235 to A84-13238.

Martin, C.S.; Chaudhry, M.H.

1983-01-01

26

Numerical methods for fluid transient analysis; Proceedings of the Applied Mechanics, Bioengineering, and Fluids Engineering Conference, Houston, TX, June 20-22, 1983  

NASA Astrophysics Data System (ADS)

Among the topics discussed are implicit methods for the solution of the one-dimensional wave equation, second-order explicit methods for transient flow analysis, a generalized implicit finite difference method for transient analysis of compressible and incompressible fluid flows, the modeling of transient two-component flow with a four-point implicit method, one-dimensional transient gas flow with internal heating, transient pressure wave radial and axial variations, and vaporous and gaseous cavitation simulation. Also discussed are variable celerity modeling by the method of characteristics, a numerical model for transients in petroleum product pipelines, solid-liquid-gas mixture one-dimensional transient flows, hydraulic transients in tunnels with concurrent open channel and pressurized flow, and waterhammer transient control with dynamic programming of valve stoking. For individual items see A84-13235 to A84-13238

Martin, C. S.; Chaudhry, M. H.

27

Annual review of fluid mechanics  

Microsoft Academic Search

This book covers the following topics: recent developments in three dimensional and unsteady turbulence boundary-layer computations; flows far from equilibrium via molecular dynamics; physics of convention-solidification interaction; the continental shelf bottom boundary layer; gravity currents in rotating systems; strange attractors in fluids: another view; eddies, waves, circulation, and mixing: statistical geofluid mechanics; regular and mach reflection of shock waves; ship

M. Van Dyke; J. V. Wehausen

1986-01-01

28

Annual review of fluid mechanics  

Microsoft Academic Search

This collection includes twenty papers. Topics covered include: notes on the study of fluid mechanics in Cambridge, England; Monte Carlo simulation of gas flows; hydrodynamic problems of ships in restricted waters; drag reduction by polymers; viscous transonic flows; dust explosions; objective methods for weather prediction; river meandering; Rossby waves, long-period oscillations of oceans and atmospheres; flows of nematic liquid crystals;

M. Van Dyke; J. V. Wehausen; J. L. Lumley

1978-01-01

29

Stirling engine performance optimization with different working fluids  

SciTech Connect

The design flexibility of Stirling cycle devices is evident from the wide variety of mechanical configurations that have been developed as well as the many differing applications that have been shown to be technically feasible. The choice of working fluid is one option that strongly influences engine design. Hydrogen permits the most compact engine (for a given power output and efficiency) of any gaseous working fluid investigated and has therefore been the choice in Stirling development programs directed at the automotive application where engine size is a major concern. Systems using helium or air are presently under development for applications where size is not as important a consideration. This paper describes calculated characteristics of engines optimized for four working fluids (hydrogen, helium, air and methane). A comparison is given between engines whose exterior dimensions are minimized and with lower rpm, lower pressure engine designs calculated by maximizing the dimensionless parameter known as the Beale number. Design point power and efficiency are the same in the resulting eight conceptual designs but great variation is shown in engine characteristics due both to working fluid differences and to the two different design objectives. 5 refs., 7 figs., 5 tabs.

Daley, J.G.; Marr, W.W.; Heames, T.J.

1986-01-01

30

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.

31

Fluid Mechanics and Homeland Security  

NASA Astrophysics Data System (ADS)

Homeland security involves many applications of fluid mechanics and offers many opportunities for research and development. This review explores a wide selection of fluids topics in counterterrorism and suggests future directions. Broad topics range from preparedness and deterrence of impending terrorist attacks to detection, response, and recovery. Specific topics include aircraft hardening, blast mitigation, sensors and sampling, explosive detection, microfluidics and labs-on-a-chip, chemical plume dispersal in urban settings, and building ventilation. Also discussed are vapor plumes and standoff detection, nonlethal weapons, airborne disease spread, personal protective equipment, and decontamination. Involvement in these applications requires fluid dynamicists to think across the traditional boundaries of the field and to work with related disciplines, especially chemistry, biology, aerosol science, and atmospheric science.

Settles, Gary S.

2006-01-01

32

Computational fluid dynamics for chemical reactor engineering  

Microsoft Academic Search

Computational Fluid Dynamics (CFD) involves the numerical solution of conservation equations for mass, momentum and energy in a flow geometry of interest, together with additional sets of equations reflecting the problem at hand. In this paper the current capabilities of CFD for chemical reactor engineering are illustrated by considering a series of examples from industrial practice. These examples form the

C. K. Harris; D. Roekaerts; F. J. J. Rosendal; F. G. J. Buitendijk; Ph. Daskopoulos; A. J. N. Vreenegoor; H. Wang

1996-01-01

33

Engine Cylinder Fluid Characteristics of Diesel Engine Converted to CNG Engine  

Microsoft Academic Search

Abstract This research has investigated the fluid characteristic effect in the engine cylinder of four-stroke direct injection diesel engine converted to port injection dedicated compressed natural gas (CNG) engine spark ignition. This research has using ,computational ,engine model,for steady-state and transient simulation. The investigation and simulation of the engine cylinder flow performance ,characteristic profile based on engine ,computational model. The

Awang Idris; Rosli Abu Bakar; Abdul Rahim Ismail

34

Diesel Engine Mechanics.  

ERIC Educational Resources Information Center

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…

Foutes, William A.

35

Diesel Engine Mechanics.  

ERIC Educational Resources Information Center

|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…

Foutes, William A.

36

FLUID MECHANICS OF ARTIFICIAL HEART VALVES  

PubMed Central

SUMMARY 1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mechanical heart valves, these complications are believed to be associated with non-physiological blood flow patterns. 2. In the present review, we provide a bird’s-eye view of fluid mechanics for the major artificial heart valve types and highlight how the engineering approach has shaped this rapidly diversifying area of research. 3. Mechanical heart valve designs have evolved significantly, with the most recent designs providing relatively superior haemodynamics with very low aerodynamic resistance. However, high shearing of blood cells and platelets still pose significant design challenges and patients must undergo life-long anticoagulation therapy. Bioprosthetic or tissue valves do not require anticoagulants due to their distinct similarity to the native valve geometry and haemodynamics, but many of these valves fail structurally within the first 10–15 years of implantation. 4. These shortcomings have directed present and future research in three main directions in attempts to design superior artificial valves: (i) engineering living tissue heart valves; (ii) development of advanced computational tools; and (iii) blood experiments to establish the link between flow and blood damage.

Dasi, Lakshmi P; Simon, Helene A; Sucosky, Philippe; Yoganathan, Ajit P

2009-01-01

37

Fluid mechanics of artificial heart valves.  

PubMed

1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mechanical heart valves, these complications are believed to be associated with non-physiological blood flow patterns. 2. In the present review, we provide a bird's-eye view of fluid mechanics for the major artificial heart valve types and highlight how the engineering approach has shaped this rapidly diversifying area of research. 3. Mechanical heart valve designs have evolved significantly, with the most recent designs providing relatively superior haemodynamics with very low aerodynamic resistance. However, high shearing of blood cells and platelets still pose significant design challenges and patients must undergo life-long anticoagulation therapy. Bioprosthetic or tissue valves do not require anticoagulants due to their distinct similarity to the native valve geometry and haemodynamics, but many of these valves fail structurally within the first 10-15 years of implantation. 4. These shortcomings have directed present and future research in three main directions in attempts to design superior artificial valves: (i) engineering living tissue heart valves; (ii) development of advanced computational tools; and (iii) blood experiments to establish the link between flow and blood damage. PMID:19220329

Dasi, Lakshmi P; Simon, Helene A; Sucosky, Philippe; Yoganathan, Ajit P

2009-02-01

38

Black holes from fluid mechanics  

NASA Astrophysics Data System (ADS)

We use the AdS/CFT correspondence in a regime where the field theory is well described by fluid mechanics to study large black holes in asymptotically locally anti de Sitter spaces. In particular, we use the fluid description to study the thermodynamics of the black holes and the existence of exotic horizon topologies in higher dimensions. First we test this method by comparing large rotating black holes in global AdSD spaces to stationary solutions of the relativistic Navier-Stokes equations on SD-2. Reading off the equation of state of this fluid from the thermodynamics of non-rotating black holes, we proceed to construct the nonlinear spinning solutions of fluid mechanics that are dual to rotating black holes. In all known examples, the thermodynamics and the local stress tensor of our solutions are in precise agreement with the thermodynamics and boundary stress tensor of the spinning black holes. Our results yield predictions for the thermodynamics of all large black holes in all theories of gravity on AdS spaces, for example, IIB string theory on AdS5 x S 5 and M theory on AdS4 x S7 and AdS7 x S 4. We then construct solutions to the relativistic Navier-Stokes equations that describe the long wavelength collective dynamics of the deconfined plasma phase of N = 4 Yang Mills theory compactified down to d = 3 on a Scherk-Schwarz circle. Our solutions are stationary, axially symmetric spinning balls and rings of plasma. These solutions, which are dual to (yet to be constructed) rotating black holes and black rings in Scherk-Schwarz compactified AdS 5, and have properties that are qualitatively similar to those of black holes and black rings in flat five dimensional gravity. We also study the stability of these solutions to small fluctuations, which provides an indirect method for studying Gregory-Laflamme instabilities. We also extend the construction to higher dimensions, allowing one to study the existence of new black hole topologies and their phase diagram.

Lahiri, Subhaneil

39

Fluid Mechanics of Urban Environments  

NASA Astrophysics Data System (ADS)

The rapid urbanization of the Earth has led to highly populated cities that act as concentrated centers of anthropogenic stressors on the natural environment. The degradation of environmental quality due to such stressors, in turn, greatly impacts human behavior. Anthropogenic stressors largely originate as a result of coupling between man-made urban elements (i.e., networks of engineering and socio-economic infrastructures) and the environment, for which surrounding fluid motions play a key role. In recent years, research efforts have been directed at the understanding and modeling of fluid motions in urban areas, infrastructure dynamics and interactions thereof, with the hope of identifying environmental impacts of urbanization and complex outcomes (or ``emergent properties'') of nominally simple interactions between infrastructures and environment. Such consequences play an important role in determining the ``resilience'' of cities under anthropogenic stressors, defined as maintaining the structure and essential functions of an urbanity without regime shifts. Holistic integrated models that meld the dynamics of infrastructures and environment as well as ``quality of life'' attributes are becoming powerful decision-making tools with regard to sustainability of urban areas (continuance or even enhancement of socio-economic activities in harmony with the environment). The rudimentary forms of integrated models are beginning to take shape, augmented by comprehensive field studies and advanced measurement platforms to validate them. This presentation deals with the challenges of modeling urban atmosphere, subject to anthropogenic forcing. An important emergent property, the Urban Heat Island, and its role in determining resilience and sustainability of cities will be discussed based on the prediction of a coupled model.

Fernando, Harindra J.

2008-11-01

40

Cutting fluid mist formation via atomization mechanisms  

Microsoft Academic Search

Cutting fluid mist is becoming an increasing concern for manufacturers as additional information is obtained on the health risks that it poses. An effective strategy to minimize the cutting fluid mist requires a fundamental understanding of cutting fluid mist formation mechanisms and the underlying process conditions affecting mist formation. In this dissertation, analytical models are developed to characterize mist formation

Yan Yue

2000-01-01

41

Instructor's Guide for Fluid Mechanics: A Modular Approach.  

ERIC Educational Resources Information Center

|This guide is designed to assist engineering teachers in developing an understanding of fluid mechanics in their students. The course is designed around a set of nine self-paced learning modules, each of which contains a discussion of the subject matter; incremental objectives; problem index, set and answers; resource materials; and a quiz with…

Cox, John S.

42

Statistical mechanics of associating fluids  

Microsoft Academic Search

Two approaches have been considered in the study of thermodynamics of associating fluids. The first approach is related to submitting equations of state based on analytic chain association theory (ACAT). An associating fluid has been assumed to be a mixture of monomer, dimer, trimer, etc., and the composition distribution of the associating species has been obtained. The second view is

Hassan Touba

1997-01-01

43

Multimedia Fluid Mechanics - Multilingual Version CD-ROM  

NASA Astrophysics Data System (ADS)

This CD-ROM offers an interactive tool for teaching undergraduate fluid mechanics. It features experiments that demonstrate fluid mechanical phenomena, animations of important principles and concepts, virtual laboratories in which students acquire data from the images, interactive computational exercises in which parameters can be varied, and other descriptive and illuminating material on applications. The material may be accessed randomly through a hyperlinked text, a search engine, a video library, and a glossary of terms. The new edition has been thoroughly updated and includes versions in English, Spanish and French.

Homsy, G. M.; Aref, H.; Breuer, K. S.; Hochgreb, S.; Koseff, J. R.; Munson, B. R.; Powell, K. G.; Robertson, C. R.; Thoroddsen, S. T.

2004-07-01

44

Fluid mechanics of pulse detonation thrusters  

NASA Astrophysics Data System (ADS)

The advantages of constant volume combustion cycle as compared to constant pressure combustion in terms of thermodynamic efficiency have focused the researches of advanced propulsion on detonation engines. The paper gives coverage of efforts undertaken during past decades in adjusting detonations for propulsion applications, and highlights new challenges in studying fluid flow dynamics relevant to onset of detonation.

Phylippov, Yu. G.; Dushin, V. R.; Nikitin, V. F.; Nerchenko, V. A.; Korolkova, N. V.; Guendugov, V. M.

2012-07-01

45

Application of Functional Analysis in Fluid Mechanics.  

National Technical Information Service (NTIS)

The work was concerned with the application of functional analysis to fluid mechanics. The specific subject dealt with is that of closed splines which were introduced by the principal investigator as the appropriate splines to solve interpolation problems...

L. G. Napolitano

1980-01-01

46

The relativistic mechanics of incompressible fluids  

NASA Astrophysics Data System (ADS)

The possible analogy between the relativistic mechanics of incompressible, isotropic fluids and relativistic electromagnetism, which has been demonstrated in the nonrelativistic case, is examined. It is shown that the equations for a perfect or a viscous fluid may be written in forms analogous to Ohm's law for a perfect conductor, the Maxwell equations and the equation for the electromagnetic potential of classical electromagnetism, by the introduction of a mechanical current. It is noted, however, that a supplementary relation governing four-velocities is different in relativistic mechanics and electromagnetism due to the nonlinearity of the mechanical field equations.

Garrido, M. S.

1982-04-01

47

The Fluid Dynamics of an Idealized Pulsed Detonation Engine  

Microsoft Academic Search

Pulsed Detonation Engines (PDEs) have received considerable attention recently because they have the potential to make a major impact in aerospace propulsion. In this talk, detailed numerical simulations are used to examine the basic fluid dynamics of an idealized pulsed detonation engine. The simulated engine consists of a tube closed at one-end and open at the other. It is shown

K. Kailasanath; G. Patnaik

2000-01-01

48

Mechanical Engineering Department technical abstracts  

SciTech Connect

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.

Denney, R.M. (ed.)

1982-07-01

49

Expose Mechanical Engineering Students to Biomechanics Topics  

ERIC Educational Resources Information Center

|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

Shen, Hui

2011-01-01

50

Standardized Curriculum for Diesel Engine Mechanics.  

ERIC Educational Resources Information Center

|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…

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

51

The Fluid Mechanics of Fires  

Microsoft Academic Search

The transport of heat and mass by fire induced flows is discussed with emphasis on the role of fire plumes. The fire plume provides the positive feedback mechanisms that determine the fire strength. It also acts as the pump which mixes the fuel and oxidizer distributes the combustion products in space and time. A brief description of some of the

Howard Baum

2005-01-01

52

Mechanical Engineering Department technical review  

SciTech Connect

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)

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

1982-01-01

53

Computational Fluid Dynamic Design of Rocket Engine Pump Components.  

National Technical Information Service (NTIS)

Integration of computational fluid dynamics (CFD) for design and analysis of turbomachinery components is needed as the requirements of pump performance and reliability become more stringent for the new generation of rocket engine. A fast grid generator, ...

W. Chen G. H. Prueger D. C. Chan A. H. Eastland

1992-01-01

54

ADDRESSING ENVIRONMENTAL ENGINEERING CHALLENGES WITH COMPUTATIONAL FLUID DYNAMICS  

EPA Science Inventory

This paper discusses the status and application of Computational Fluid Dynamics )CFD) models to address environmental engineering challenges for more detailed understanding of air pollutant source emissions, atmospheric dispersion and resulting human exposure. CFD simulations ...

55

Fluid design studies of integrated modular engine system  

NASA Astrophysics Data System (ADS)

A study was performed to develop a fluid system design and show the feasibility of constructing an integrated modular engine (IME) configuration, using an expander cycle engine. The primary design goal of the IME configuration was to improve the propulsion system reliability. The IME fluid system was designed as a single fault tolerant system, while minimizing the required fluid components. This study addresses the design of the high pressure manifolds, turbopumps and thrust chambers for the IME configuration. A physical layout drawing was made, which located each of the fluid system components, manifolds and thrust chambers. Finally, a comparison was made between the fluid system designs of an IME system and a non-network (clustered) engine system.

Frankenfield, Bruce; Carek, Jerry

1993-06-01

56

General Noncommuting Curvilinear Coordinates and Fluid Mechanics  

NASA Astrophysics Data System (ADS)

We show that restricting the states of a charged particle to the lowest Landau level introduces noncommutativity between general curvilinear coordinate operators. The Cartesian, circular cylindrical and spherical polar coordinates are three special cases of our quite general method. The connection between U(1) gauge fields defined on a general noncommuting curvilinear coordinates and fluid mechanics is explained. We also recognize the Seiberg-Witten map from general noncommuting to commuting variables as the quantum correspondence of the Lagrange-to-Euler map in fluid mechanics.

Alavi A., S.

2006-10-01

57

Mod I automotive Stirling engine mechanical development  

Microsoft Academic Search

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

Simetkosky

1984-01-01

58

General Noncommuting Curvilinear Coordinates and Fluid Mechanics  

Microsoft Academic Search

We show that restricting the states of a charged particle to the lowest Landau level introduces noncommutativity between general curvilinear coordinate operators. The Cartesian, circular cylindrical and spherical polar coordinates are three special cases of our quite general method. The connection between U(1) gauge fields defined on a general noncommuting curvilinear coordinates and fluid mechanics is explained. We also recognize

S. A. Alavi

2006-01-01

59

General noncommuting curvilinear coordinates and fluid Mechanics  

Microsoft Academic Search

We show that restricting the states of a charged particle to the lowest Landau level introduces noncommutativity between general curvilinear coordinate operators. The cartesian, circular cylindrical and spherical polar coordinates are three special cases of our quite general method. The connection between U(1) gauge fields defined on a general noncommuting curvilinear coordinates and fluid mechanics is explained. We also recognize

S. A. Alavi

2006-01-01

60

Leonardian Fluid Mechanics in the Manuscript F.  

National Technical Information Service (NTIS)

This is the thirteenth IIHR Monograph the author has written on the Leonardian science of flow and transport phenomena. The Manuscript F contains a great deal of notes and drawings on fluid mechanics and hydraulics and this is a volume requiring even more...

E. Macagno

1992-01-01

61

Annual review of fluid mechanics. Volume 19  

Microsoft Academic Search

The present evaluation of the status of fluid mechanical research gives attention to confined vortices in flow machinery, turbulent secondary flows, upstream blocking and airflow over mountains, critical point concept descriptions of eddying motions and flow patterns, viscoelastic flows through contractions, the theory of solute transport by groundwater, tsunamis, turbulent premixed flame behavior, and viscous fingering in porous media. Also

John L. Lumley; Milton van Dyke; Helen L. Reed

1987-01-01

62

Fluids  

NSDL National Science Digital Library

This Topic in Depth explores the Web's offerings on the physics of fluids. By an educational Web site called School for Champions, the first site is the Fluids lesson plan (1). Here, students or anyone interested can read about the basics of fluids and then take a short interactive quiz on the topic. The second site is maintained by Steve Lower of the Department of Chemistry at Simon Fraser University called Liquids and their Vapors (2). This Adobe Acrobat (.pdf) file contains an eighteen-page document that covers topics such as properties of liquids and changes of state. The next site contains an interactive multimedia activity presented by explorescience.com called Floating Log (3). The site allows users to explore how a fluid can affect buoyancy by letting them change the mass of the log and the fluid's density. The next site from Purdue University's Chemical Education Web site is called Liquids (4). This page describes the structure of liquids, what kinds of materials form liquids, vapor pressure, and more. The fifth site, offered by Professor M.S. Cramer at the College of Engineering at Virginia Tech, is entitled Gallery of Fluid Dynamics (5). It contains movies, animations, photographs, and descriptions of various fluid mechanics topics such as condensation, shock waves, and supersonic cars. Next comes the Innovative Technology Solutions Corporation's Fundamental Fluid Mechanics Movies Web site (6). Over thirty short films show how fluids move in various conditions including gravity waves, fire, material transport, and hydraulics. From the University of Waterloo's Department of Mechanical Engineering-Microelectronics Heat Transfer Laboratory comes the next site, called the Fluid Properties Calculator (7). This online tool allows users to select a fluid and enter a temperature to calculate various parameters such as density, viscosity, specific heat, and thermal diffusivity. The last site is the online journal Physics of Fluids (8), which is published monthly by the American Institute of Physics with the cooperation of The American Physical Society Division of Fluid Dynamics. The journal is "devoted to the publication of original theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and complex or multiphase fluids" and provides free full-text articles for online viewing.

Brieske, Joel A.

2002-01-01

63

Standardized Curriculum for Outboard Marine Engine Mechanics.  

ERIC Educational Resources Information Center

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

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

64

Standardized Curriculum for Outboard Marine Engine Mechanics.  

ERIC Educational Resources Information Center

|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

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

65

MEGA (Mechanical Engineering General Analysis) User's Document.  

National Technical Information Service (NTIS)

MEGA (Mechanical Engineering General Analysis) is a FORTRAN computer code, which allows the user to analyze data, generated by a variety of data acquisition systems currently being used by Engineering Sciences Division (DVM Node, Transient Recorder, Fract...

B. Voegeli C. K. Wong

1983-01-01

66

Technical abstracts: Mechanical engineering, 1990  

SciTech Connect

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.

Broesius, J.Y. (comp.)

1991-03-01

67

Small Engines and Outboard Marine Mechanics Curriculum.  

ERIC Educational Resources Information Center

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…

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

68

Mechanical Oscillators in Inviscid Compressible Fluids  

NASA Astrophysics Data System (ADS)

Mechanical resonators of different kinds are widely used to probe the properties of superfluid helium. When immersed in fluid medium, the oscillator response changes due to added inertia and dissipation compared to that of vacuum. The surrounding fluid is often assumed incompressible to simplify the analysis. This approximation is justified by the argument that the wavelength of sound is much larger than the relevant length scale of the resonator. We study mechanical oscillators with various geometries by means of numerical simulations. The results demonstrate that compressibility of the medium has a significant effect even when the conditions for the incompressibility approximation are usually assumed to hold. Therefore in precise measurements compressibility should be taken into account. This study is motivated by the desire to understand better the behavior of a quartz tuning fork resonator immersed in superfluid helium.

Rysti, J.; Tuoriniemi, J.

2013-05-01

69

Annual review of fluid mechanics. Volume 22  

Microsoft Academic Search

Topics presented include rapid granular flows, issues in viscoelastic fluid mechanics, wave loads on offshore structures, boundary layers in the general ocean circulation, parametrically forced surface waves, wave-mean flow interactions in the equatorial ocean, and local and global instabilities in spatially developing flows. Also presented are aerodynamics of human-powered flight, aerothermodynamics and transition in high-speed wind tunnels at NASA-Langley, wakes

John L. Lumley; Milton van Dyke; Helen L. Reed

1990-01-01

70

Annual review of fluid mechanics. Volume 16  

SciTech Connect

Selected topics in fluid mechanics are examined in reviews of recent theoretical and experimental research. Graphs, diagrams, drawings, and photographs taken from and/or summarizing the publications surveyed are provided. Topics discussed include wave action and wave/mean-flow interaction, numerical simulation of turbulent flows, nonlinear interactions in liquid He II, secondary flow in curved open channels, vortex shedding from oscillating bluff bodies, optical techniques, aeroacoustics of turbulent shear flows, supercritical-wing design, and perturbed free shear layers.

Van Dyke, M.; Wehausen, J.V.; Lumley, J.L.

1984-01-01

71

Teaching Continuum Mechanics in a Mechanical Engineering Program  

ERIC Educational Resources Information Center

|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…

Liu, Yucheng

2011-01-01

72

Dictionary of mechanical engineering, third edition  

SciTech Connect

This dictionary provides coverage of terms currently used in mechanical and production engineering. Since the publication of the previous edition ten years ago many new terms have been added to the engineer's vocabulary, particularly in fields related to robotics, automation, and computer applications. This edition has been revised to cover a broader range of topics and contains many new illustrations and over 700 new entries. There are also appendices listing engineering symbols and abbreviations, and an extensive list of engineering organizations.

Nayler, G.H.F.

1985-01-01

73

Comparing fluid mechanics models with experimental data.  

PubMed Central

The art of modelling the physical world lies in the appropriate simplification and abstraction of the complete problem. In fluid mechanics, the Navier-Stokes equations provide a model that is valid under most circumstances germane to animal locomotion, but the complexity of solutions provides strong incentive for the development of further, more simplified practical models. When the flow organizes itself so that all shearing motions are collected into localized patches, then various mathematical vortex models have been very successful in predicting and furthering the physical understanding of many flows, particularly in aerodynamics. Experimental models have the significant added convenience that the fluid mechanics can be generated by a real fluid, not a model, provided the appropriate dimensionless groups have similar values. Then, analogous problems can be encountered in making intelligible but independent descriptions of the experimental results. Finally, model predictions and experimental results may be compared if, and only if, numerical estimates of the likely variations in the tested quantities are provided. Examples from recent experimental measurements of wakes behind a fixed wing and behind a bird in free flight are used to illustrate these principles.

Spedding, G R

2003-01-01

74

Small Engine Mechanics. Post Secondary Curriculum Guide.  

ERIC Educational Resources Information Center

This curriculum guide was designed for use in postsecondary small engine mechanics education programs in Georgia. Its purpose is to provide for the development of entry level skills in small engine mechanics in the areas of knowledge, theoretical structure, tool usage, diagnostic ability, related supportive skills, and occupational survival…

Watkins, James F.; And Others

75

Mechanical Engineering Department engineering research: Annual report, FY 1986  

Microsoft Academic Search

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

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

1986-01-01

76

Fluid heating attachment for automobile engine cooling systems  

SciTech Connect

This patent describes a fluid heating attachment for automobile engines cooling systems with a device for warming the engine and prewarming the washer fluid when the engine is not running, and for also warming the washer fluid when the engine is running. The attachment consists of: a housing having a heating chamber and having an inlet and an outlet connected in communication with the chamber, the housing inlet and outlet being connected in communication with the radiator outlet hose and space heater supply hose, respectively, thus to connect the chamber in the cooling system as part of the flow path of coolant circulated through the system and thereby fill the chamber with the circulated coolant; a tubular conduit means for windshield washer fluid, supported within the chamber in position to be substantially wholly immersed in the coolant filling the chamber; the conduit means including inflow and outflow ends projecting exteriorly of the chamber and respectively connected to the inlet and outlet end portions of the windshield washer fluid supply line to provide a heated supply of washer fluid for the spray head; and heating means within the chamber for elevating the temperature of the coolant and the washer fluid therein, the heating means comprising an electrical heating element wholly immersed in the coolant within the chamber in laterally spaced relation to the conduit means and adapted for connection to a supply of house current, from the housing to the space heater supply hose and into the upper end of the block, and thereafter downwardly through the block to the lower end thereof to displace and force upwardly coolant that is of a lower temperature.

Linker, R.E.; Linker, M.P.

1986-03-11

77

The Fluid Dynamics of a Pulse Detonation Engine-IV  

Microsoft Academic Search

Pulsed Detonation Engines (PDEs) have received considerable attention recently because they have the potential to make a major impact in aerospace propulsion. Previously, the fluid dynamics of an idealized PDE, consisting of a tube closed at one end and open at the other has been presented. Typically, gaseous fuels are used in both experiments and simulations. However, for most practical

K. Kailasanath; S. Cheatham

2003-01-01

78

The Fluid Dynamics of a Pulse Detonation Engine-III  

Microsoft Academic Search

Pulsed Detonation Engines (PDEs) have received considerable attention recently because they have the potential to make a major impact in aerospace propulsion. Previously, we showed that the fluid dynamics of an idealized PDE, consisting of a tube closed at one end and open at the other is quite complex and depends strongly on the boundary conditions at the open end.

K. Kailasanath; Chiping Li

2002-01-01

79

The Fluid Dynamics of a Pulse Detonation Engine-II  

Microsoft Academic Search

Pulsed Detonation Engines (PDEs) have received considerable attention recently because they have the potential to make a major impact in aerospace propulsion. Last year, we showed that the fluid dynamics of an idealized PDE, consisting of a tube closed at one end and open at the other is quite complex and depends strongly on the boundary conditions at the open

K. Kailasanath; Gopal Patnaik; Chiping Li

2001-01-01

80

Computational fluid dynamics in aerospace engineering at Wichita State University  

Microsoft Academic Search

A summary of recent research performed in the department of Aerospace Engineering of the Wichita State University in the field of Computational Fluid Dynamics is presented. Computer codes developed and solutions obtained for a variety of flow conditions are also presented. The following subject areas are covered: steady and unsteady free and impinging 2D jet flows; viscous and inviscid solutions

Steve Klausmeyer; S. Reddy; X. Lui; M. Papadakis

1991-01-01

81

The role of computational fluid dynamics in aeronautical engineering  

Microsoft Academic Search

Some of the available methods in actual design and the trend in computational fluid dynamics (CFD) are presented. Inviscid linear flow, the panel method and the vortex lattice method are the only methods for analyzing arbitrary practical configurations and are the most useful engineering tools available. Although these approach a relatively mature level, the improvement required for these methods are:

J. Okumura; T. Jyonouchi; K. Sawada

1983-01-01

82

Computational fluid dynamic design of rocket engine pump components  

Microsoft Academic Search

Integration of computational fluid dynamics (CFD) for design and analysis of turbomachinery components is needed as the requirements of pump performance and reliability become more stringent for the new generation of rocket engine. A fast grid generator, designed specially for centrifugal pump impeller, which allows a turbomachinery designer to use CFD to optimize the component design will be presented. The

Wei-Chung Chen; George H. Prueger; Daniel C. Chan; Anthony H. Eastland

1992-01-01

83

Mod I automotive Stirling engine mechanical development  

SciTech Connect

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).

Simetkosky, M.

1984-01-01

84

Mechanobiology of engineered cartilage cultured under a quantified fluid-dynamic environment  

Microsoft Academic Search

Natural cartilage remodels both in vivo and in vitro in response to mechanical forces and hence mechanical stimulation is\\u000a believed to have a potential as a tool to modulate extra-cellular matrix synthesis in tissue-engineered cartilage. Fluid-induced\\u000a shear is known to enhance chondrogenesis on animal cells. A well-defined hydrodynamic environment is required to study the\\u000a biochemical response to shear of three-dimensional

M. T. Raimondi; F. Boschetti; L. Falcone; G. B. Fiore; A. Remuzzi; E. Marinoni; M. Marazzi; R. Pietrabissa

2002-01-01

85

Potential fluid mechanic pathways of platelet activation.  

PubMed

Platelet activation is a precursor for blood clotting, which plays leading roles in many vascular complications and causes of death. Platelets can be activated by chemical or mechanical stimuli. Mechanically, platelet activation has been shown to be a function of elevated shear stress and exposure time. These contributions can be combined by considering the cumulative stress or strain on a platelet as it is transported. Here, we develop a framework for computing a hemodynamic-based activation potential that is derived from a Lagrangian integral of strain rate magnitude. We demonstrate that such a measure is generally maximized along, and near to, distinguished material surfaces in the flow. The connections between activation potential and these structures are illustrated through stenotic flow computations. We uncover two distinct structures that may explain observed thrombus formation at the apex and downstream of stenoses. More broadly, these findings suggest fundamental relationships may exist between potential fluid mechanic pathways for mechanical platelet activation and the mechanisms governing their transport. PMID:22782543

Shadden, Shawn C; Hendabadi, Sahar

2012-07-11

86

Unsaturated Soil Mechanics in Engineering Practice  

Microsoft Academic Search

Unsaturated soil mechanics has rapidly become a part of geotechnical engineering practice as a result of solutions that have emerged to a number of key problems or challenges. The solutions have emerged from numerous research studies focusing on issues that have a hindrance to the usage of unsaturated soil mechanics. The primary challenges to the implementation of unsaturated soil mechanics

Delwyn G. Fredlund

2006-01-01

87

Mechanics and Engineering in Ireland.  

National Technical Information Service (NTIS)

The purpose of this report is to describe the activities and research of the staff in engineering and related departments at each of four colleges in Eire: There are two universities in Eire, the Univ. of Dublin and the National University of Ireland (NUI...

H. E. Williams

1967-01-01

88

Fluid mechanics experiments in oscillatory flow. Volume 1  

SciTech Connect

Results of a fluid mechanics measurement program is oscillating flow within a circular duct are present. The program began with a survey of transition behavior over a range of oscillation frequency and magnitude and continued with a detailed study at a single operating point. Such measurements were made in support of Stirling engine development. Values of three dimensionless parameters, Re{sub max}, Re{sub W}, and A{sub R}, embody the velocity amplitude, frequency of oscillation and mean fluid displacement of the cycle, respectively. Measurements were first made over a range of these parameters which included operating points of all Stirling engines. Next, a case was studied with values of these parameters that are representative of the heat exchanger tubes in the heater section of NASA`s Stirling cycle Space Power Research Engine (SPRE). Measurements were taken of the axial and radical components of ensemble-averaged velocity and rms-velocity fluctuation and the dominant Reynolds shear stress, at various radial positions for each of four axial stations. In each run, transition from laminar to turbulent flow, and in reverse, were identified and sufficient data was gathered to propose the transition mechanism. Models of laminar and turbulent boundary layers were used to process the data into wall coordinates and to evaluate skin friction coefficients. Such data aids in validating computational models and is useful in comparing oscillatory flow characteristics to those of fully-developed steady flow. Data were taken with a contoured entry to each end of the test section and with flush square inlets so that the effects of test section inlet geometry on transition and turbulence are documented. The following is presented in two-volumes. Volume I contains the text of the report including figures and supporting appendices. Volume II contains data reduction program listings and tabulated data (including its graphical presentation).

Seume, J.; Friedman, G.; Simon, T.W. [Univ. of Minnesota, Minneapolis, MN (United States)

1992-03-01

89

Fluid mechanics of spinner-flask bioreactors  

NASA Astrophysics Data System (ADS)

The dynamic environment within bioreactors used for in vitro tissue growth has been observed to affect the development of mammalian cells. Many studies have shown that moderate mechanical stress enhances growth of some tissues whereas high shear levels and turbulence seem to damage cells. In order to optimize the design and the operating conditions of bioreactors, it is important to understand the fluid-dynamic characteristics and to control the stress levels within these devices. The present research focuses on the characterization of the flow field within a spinner-flask bioreactor. The dynamic properties of the flow are investigated experimentally using particle-image velocimetry with a refractive-index-matched model. Phase-locked ensemble-averaging is employed to provide some information on the turbulence characteristics of the model culture medium in the vicinity of a model tissue construct.

Sucosky, Philippe; Neitzel, G. Paul

2000-11-01

90

Engineering mechanics: statics and dynamics. [Textbook  

SciTech Connect

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)

Sandor, B.I.

1983-01-01

91

The Fluid Dynamics of a Pulse Detonation Engine-V  

Microsoft Academic Search

Pulsed Detonation Engines (PDE) have received considerable attention recently because they have the potential to make a major impact in aerospace propulsion. Previously, several aspects of the fluid dynamics of a PDE have been presented at these meetings. Reliable and repeated low-energy initiation of detonations in the high-speed flow in PDEs operating on fuel-air mixtures is one of the remaining

K. Kailasanath; C. Li

2004-01-01

92

Valve operating mechanism for internal combustion engine  

SciTech Connect

This patent describes a valve operating mechanism for operating valves of a particular cylinder of an internal combustion engine, comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine and having at least one cam; cam followers, one of which slidably engages with the cam for selectively operating the valves according to a cam profile of the cam; and means for selectively interconnecting and disconnecting the cam followers to operate the valves differently in different speed ranges of the internal combustion engine, the speed ranges including a range in which all of the valves remain inoperative.

Inoue, K.; Nagahiro, K.; Ajiki, Y.; Katoh, M.

1988-12-13

93

Valve operating mechanism for internal combustion engine  

SciTech Connect

A valve operating mechanism for operating a single valve of a particular cylinder of an internal combustion engine is described comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine; a plurality of cams on the camshaft with each of the cams bearing a different cam profile; a plurality of cam followers, each of which slidably engages one of the cams for selectively operating the valve according to the profile of the selected cam and one of which engages the valve; and means for selectively interconnecting and disconnecting the respective cam followers to operate the valve differently in different speed ranges of the internal combustion engine.

Inoue, K.; Nagahiro, K.; Ajiki, Y.; Katoh, M.

1988-12-27

94

Reliability Engineering and Robust Design: New Methods for Thermal\\/Fluid Engineering  

Microsoft Academic Search

Recent years have witnessed more improvement to the SINDA\\/FLUINT thermohydraulic analyzer than at any other time in its long history. These improvements have included not only expansions in analytic power, but also the addi- tions of high-level modules that offer revolutions in thermal\\/ fluid engineering itself. One such high-level module, \\

Brent A. Cullimore

2000-01-01

95

Reliability Engineering and Robust Design: New Methods for Thermal\\/Fluid Engineering  

Microsoft Academic Search

Recent years have witnessed more improvement to the SINDA\\/FLUINT thermohydraulic analyzer than at any other time in its long history. These improvements have included not only expansions in analytic power, but also the additions of high-level modules that offer revolutions in thermal\\/fluid engineering itself. One such high-level module, \\

Brent A. Cullimore; Glenn T. Tsuyuki

2002-01-01

96

Fluid dynamic derivatives: Marine and wind engineering approaches  

Microsoft Academic Search

An alternative formulation, applied in marine and air craft fluid dynamics, of the traditional aerodynamic derivatives model, is presented. The relationship between the derivatives of the two models is derived, from which the exact interdependencies of the derivatives of the traditional model can be found. A forced motion model testing device, termed a planar motion mechanism (PMM), applicable for the

Andreas G. Jensen

1997-01-01

97

Micro electromechanical systems (MEMS) for mechanical engineers  

SciTech Connect

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 engineers made impact. Through a basic understanding of the history of MEMS, the background physics and scaling in micromechanical systems, and an introduction to baseline MEMS processes, a mechanical engineer should be well on his way to Alice's wonderland in the ever-exciting playground of MEMS.

Lee, A. P., LLNL

1996-11-18

98

Mechanical engineering capstone senior design textbook  

NASA Astrophysics Data System (ADS)

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.

Barrett, Rolin Farrar, Jr.

99

The 2008 summary of scientific productivity of chemical engineering, civil engineering and mechanical engineering professionals in Taiwan  

Microsoft Academic Search

This report carefully examined the scientific productivity of chemical engineering, civil engineering and mechanical engineering professionals in Taiwan in 2008 by analyzing the authorship for all journal papers listed in the ISI Web of Science from chemical engineering, mechanical engineering, and civil engineering related departments and institutes in Taiwan. The result from analysis of the authorship data still follows a

Ya-Ling Cheng; Mi-Ni Ho; Duu-Jong Lee

2010-01-01

100

Fluid mechanics of microfluidic membraneless filter  

NSDL National Science Digital Library

If the Reynolds number is small enough (Re<<1), then two fluids can flow in parallel in direct contact, exchanging momentum and species only by diffusion. If the interface is stable, then this system can be used as a filter. In this problem, the flow fields in both fluids are found.

Krane, Matthew J.; Martinez, Carlos

2008-10-25

101

Mechanobiology and the microcirculation: cellular, nuclear and fluid mechanics  

PubMed Central

Endothelial cells are stimulated by shear stress throughout the vasculature and respond with changes in gene expression and by morphological reorganization. Mechanical sensors of the cell are varied and include cell surface sensors that activate intracellular chemical signaling pathways. Here, possible mechanical sensors of the cell including reorganization of the cytoskeleton and the nucleus are discussed in relation to shear flow. A mutation in the nuclear structural protein lamin A, related to Hutchinson Gilford progeria syndrome, is reviewed specifically since the mutation results in altered nuclear structure and stiffer nuclei; animal models also suggest significantly altered vascular structure. Nuclear and cellular deformation of endothelial cells in response to shear stress provides partial understanding of possible mechanical regulation in the microcirculation. Increasing sophistication of fluid flow simulations inside the vessel is also an emerging area relevant to the microcirculation since visualization in situ is difficult. This integrated approach to study – including medicine, molecular and cell biology, biophysics and engineering – provides a unique understanding of multi-scale interactions in the microcirculation.

Dahl, Kris Noel; Kalinowski, Agnieszka; Pekkan, Kerem

2010-01-01

102

Mechanical control of tissue-engineered bone.  

PubMed

ABSTRACT: Bone is a load-bearing tissue and physical forces play key roles in the development and maintenance of its structure. Mechanical cues can stimulate the expression of an osteogenic phenotype, enhance matrix and mineral deposition, and influence tissue organization to improve the functional outcome of engineered bone grafts. In recent years, a number of studies have investigated the effects of biophysical forces on the bone formation properties of osteoprogenitor cells. The application of physiologically relevant stimuli to tissue-engineered bone may be determined through observation and understanding of forces to which osteoblasts, osteoclasts, and osteocytes are exposed in native bone. Subsequently, these cues may be parameterized and their effects studied in well-defined in vitro systems. The osteo-inductive effects of three specific mechanical cues - shear stress, substrate rigidity, and nanotopography - on cells cultured in monolayer or in three-dimensional biomaterial scaffolds in vitro are reviewed. Additionally, we address the time-dependent effects of mechanical cues on vascular infiltration and de novo bone formation in acellular scaffolds implanted into load-bearing sites in vivo. Recent studies employing cutting-edge advances in biomaterial fabrication and bioreactor design have provided key insights into the role of mechanical cues on cellular fate and tissue properties of engineered bone grafts. By providing mechanistic understanding, future studies may go beyond empirical approaches to rational design of engineering systems to control tissue development. PMID:23369796

Hung, Ben P; Hutton, Daphne L; Grayson, Warren L

2013-01-31

103

MECHANICAL ENGINEERING CURRICULUM DEVELOPMENT FOR QASSIM UNIVERSITY  

Microsoft Academic Search

ABSTRCT In this paper, an integrated methodology for the development of a mechanical engineering curriculum is presented. The methodology first identifies the program educational objectives, which upon achievement will lead to the expected program outcomes established by ABET, then it identifies the key elements of the curriculum and the method to integrate them through a five year program. The elements

Mohamed M. ElMadany; Bassam A. AlBassam

2006-01-01

104

Shift mechanism for engine starting apparatus  

Microsoft Academic Search

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

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

1986-01-01

105

Seal mechanism for a Stirling engine  

Microsoft Academic Search

A seal mechanism for a Stirling engine of the type having a displacer piston and a power piston slidably disposed inside a cylinder, the displacer piston having an upper ring groove and a lower ring groove and the power piston having one or more ring grooves, is described comprising: an upper displacer piston ring which is mounted in the upper

K. Kawajiri; M. Fujiwara; T. Nomaguchi; K. Tsuchino; Y. Kazumoto

1988-01-01

106

Gasoline Engine Mechanics. Performance Objectives. Basic Course.  

ERIC Educational Resources Information Center

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)…

Jones, Marion

107

Expert tutoring system for teaching mechanical engineering  

Microsoft Academic Search

This paper describes the work undertaken, at the Higher Technical School of Industrial Engineers of Gijón, for the development of computer aided systems, in the line of expert systems, concentrating research, and development in the field of mechanical design. We are using this software as an integrated tool in our work for teaching machine design. Models to develop the software

Ricardo Tucho Navarro; J. M. Sierra; J. E. Fernández; R. Vijande; G. Morís

2003-01-01

108

Vascular fluid mechanics, the arterial wall, and atherosclerosis.  

PubMed

Atherosclerosis, a disease of large- and medium-size arteries, is the chief cause of death in the United States and in most of the western world. Severe atherosclerosis interferes with blood flow; however, even in the early stages of the disease, i.e. during atherogenesis, there is believed to be an important relationship between the disease processes and the characteristics of the blood flow in the arteries. Atherogenesis involves complex cascades of interactions among many factors. Included in this are fluid mechanical factors which are believed to be a cause of the highly focal nature of the disease. From in vivo studies, there is evidence of hemodynamic influences on the endothelium, on intimal thickening, and on monocyte recruitment. In addition, cell culture studies have demonstrated the important effect of a cell's mechanical environment on structure and function. Most of this evidence is for the endothelial cell, which is believed to be a key mediator of any hemodynamic effect, and it is now well documented that cultured endothelial monolayers, in response to a fluid flow-imposed laminar shear stress, undergo a variety of changes in structure and function. In spite of the progress in recent years, there are many areas in which further work will provide important new information. One of these is in the engineering of the cell culture environment so as to make it more physiologic. Animal studies also are essential in our efforts to understand atherogenesis, and it is clear that we need better information on the pattern of the disease and its temporal development in humans and animal models, as well as the specific underlying biologic events.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1522720

Nerem, R M

1992-08-01

109

Research Group Introduction : Mechanical Control Engineering Laboratory, Mechanical Engineering Department, Shibaura Institute of Technology  

NASA Astrophysics Data System (ADS)

Mechanical Control Engineering Laboratory focuses on the control theory and implementation for the robotic applications. The research themes include network based tele-operation, mobile robots control for network relay, autonomous outdoor mobile robot and biped robot.

??, ?

110

Valve operating mechanism for internal combustion engine  

SciTech Connect

This patent describes a valve operating mechanism of operating valves of an internal combustion engine, comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine and having an array of three cams each having a different cam profile and including a high-speed cam position at one end of the array; three cam followers held in sliding contact with the cams, respectively, for operating the valves according to the cam profiles of the cams; and means for selectively interconnecting and disconnecting the cam followers to operate the valves at different valve timings in different speed ranges of the internal combustion engine, the speed ranges including a high-speed range in which all of the valves are controlled by the cam profile of the high-speed cam.

Inoue, K.; Nagahiro, K.; Ajiki, Y.; Katoh, M.

1988-12-06

111

Bernoulli and Newton in Fluid Mechanics  

ERIC Educational Resources Information Center

|Bernoulli's theorem can be better understood with the aid of Newton's laws and the law of conservation of energy. Application of this theorem should involve only cases dealing with an interchange of velocity and pressure within a fluid under isentropic conditions. (DF)|

Smith, Norman F.

1972-01-01

112

Fluid Mechanics in the Subtectorial Space  

NASA Astrophysics Data System (ADS)

In the subtectorial space, momentum is transported by the fluid to the stereocilia of the inner hair cell (IHC), resulting in bending of the hair bundle. The fluid must pass through the v-shaped arrangement of the outer hair cell (OHC) stereocilia and is "squeezed" between the tectorial membrane (TM) and the reticular lamina, especially due to the Hensen's stripe. Here, we analyze the flow field by means of numerical discretization. Since the geometry is complex, the finite-element-method is employed. An implementation is developed which allows computation in the frequency domain, based on a pressure stabilised velocity formulation. Matrix coupling with the structure is accomplished and a single solution step of the whole system matrix is sufficient to retrieve the displacement field of the fluid and structural parts. The proposed method allows a solution of the fluid-structure interaction in the subtectorial space within a reasonable time. For a two-dimensional mesh with 120,000 degrees of freedom of a complete cross-section of the organ of Corti, including stereocilia, the solution time is less than 20 seconds on a convential PC.

Baumgart, J.; Chiaradia, C.; Fleischer, M.; Yarin, Y.; Grundmann, R.; Gummer, A. W.

2009-02-01

113

Preparation of nano fluids by mechanical method  

NASA Astrophysics Data System (ADS)

Nanofluids are conventional heat transfer fluids that contain nano particles of metals, oxides, carbides, nitrides, or nanotubes. Nanofluids exhibit enhanced thermal conductivity and heat transfer coefficients compared to the base fluids. This paper presents the procedure for preparing nanofluids consisting of Copper and Aluminium nano powders in base fluids. Copper and Aluminium nano powders were produced by planetary ball wet milling at 300rpm for 50hrs. Toluene was added to ensure wet milling. These powders were characterized in XRD and SEM for their purity, particle size and shape. The XRD results confirmed the final particle sizes of Copper and Aluminium in the nano range. Then the 0.01 gm of nano metal powders was added in 150 ml of double distilled water and magnetic stirring was done at 1500 rpm for 15 minutes. Sodium lauryl sulphate (0.05%) was added in water as surfactant to ensure the stability of the dispersion. Ultrasonication in the 3000 watts bath was done for 10 minutes to enhance the uniform dispersion of metal powders in water. The pH, dynamic viscosity, ionic conductivity and the stability of the fluids were determined for further usage of synthesized nanofluids as coolant during grinding operation.

Boopathy, J.; Pari, R.; Kavitha, M.; Angelo, P. C.

2012-07-01

114

Fluid mechanics in crystal growth - The 1982 Freeman scholar lecture  

Microsoft Academic Search

An attempt is made to unify the current state of knowledge in crystal growth techniques and fluid mechanics. After identifying important fluid dynamic problems for such representative crystal growth processes as closed tube vapor transport, open reactor vapor deposition, and the Czochralski and floating zone melt growth techniques, research results obtained to date are presented. It is noted that the

Simon Ostrach

1983-01-01

115

Fundamental studies of fluid mechanics and stability in porous media  

SciTech Connect

This report summarizes accomplished and proposed work for the fundamental studies of fluid mechanics and stability in porous media. Topics discussed include: viscous fingering in miscible displacements; polymer flow interactions in free shear layers of viscoelastic fluids; effect of nonmonotonic viscosity profiles on the stability of miscible displacements in porous media; and references. (JL)

Homsy, G.M.

1991-08-01

116

Radionuclide technique in mechanical engineering in Germany  

Microsoft Academic Search

A subject of increasing application of cyclotron machines is the RadionuclideTechnique inMechanical Engineering (RTM), a measuring system that enables wear and corrosion diagnostics of components of operating machines, apparatus or processing plants. The three components of the RTM-system, the thin layer-activation at the cyclotron, the measuring methods and the measuring instruments for application in industry, have been developed systematically at

P. Fehsenfeld; A. Kleinrahm; H. Schweickert

1992-01-01

117

Fluid Transport Mechanisms in Breast Gross Cystic Disease.  

National Technical Information Service (NTIS)

The goal of the present work was to develop a model system to study the mechanisms of fluid transport across mammary epithelia. In addition we also examined whether the epithelial ion Cl and Na channels (cystic fibrosis transmembrane conductance regulator...

S. S. Miller

1999-01-01

118

Resource Letter MPF-1: Mechanical Properties of Fluids  

ERIC Educational Resources Information Center

|Presents an annotated bibliography concerning the mechanical properties of fluids, including topics for use at elementary, secondary, undergraduate, and graduate levels. Indicates that the material can particularly help college physicists in improving course contents in specified fields of physics. (CC)|

Stanley, R. C.

1974-01-01

119

Software for principles of fluid mechanics  

SciTech Connect

This book is intended as a software supplement and provides a means for solving problems rapidly to determine the relative importance of flow and environmental parameters. Topics covered include the following: momentum equation: rocket trajectory; Bernoulli's equation: pipe plug-flow or Bernoulli's equation: tank drawing; fluid statics: submerged gate, or fluid statics: manometry; laminar flow: pipe fittings plus straight pipe, or laminar external flow: between parallel planes; ideal flow: plot of pressure distribution on a cylinder with circulation; laminar external flow: drag force and friction coefficient; turbulent external flow: drag force and friction coefficient on flat plate; turbulent external flow: drag force and friction coefficient on sphere; turbulent pipe flow: fittings plus straight sections (moody diagram); turbulent channel flow; isentropic compressible flow; normal shocks: property changes errors; choked nozzle flow; pump curve and system curve simultaneous solution; and fan affinity laws.

Kreider, J.F.

1985-01-01

120

Recruitment of Neural Mechanisms Supporting Fluid Intelligence  

Microsoft Academic Search

Fluid intelligence (gf) influences performance across many cogni- tive domains. It is affected by both genetic and environmental fac- tors. Tasks tapping gf activate a network of brain regions including the lateral prefrontal cortex (LPFC), the presupplementary motor area\\/anterior cingulate cortex (pre-SMA\\/ACC), and the intraparietal sulcus (IPS). In line with the ''intermediate phenotype'' approach, we assessed effects of a polymorphism

Sonia J. Bishop; John Fossella; Camilla J. Croucher; John Duncan

121

Summer institute in fluid mechanics of the environment  

Microsoft Academic Search

Summer Institute in Fluid Mechanics of the Environment will be offered from June 12 through August 4, 1972, at Colorado State University, Fort Collins, Colorado, under support of the National Science Foundation. J.E. Cermak, Professor-in-Charge of the Fluid Mechanics Program, will direct the Institute with the assistance of R.N. Meroney. The subject matter will he focused on the description, analysis,

Anonymous

1972-01-01

122

The Fluid Dynamics of a Pulse Detonation Engine-VI  

NASA Astrophysics Data System (ADS)

Pulsed Detonation Engines (PDEs) have received considerable attention recently because they have the potential to make a major impact in aerospace propulsion. Previously, several aspects of the fluid dynamics of an idealized PDE, consisting of a tube closed at one end and open at the other have been presented. Typically, gaseous fuels are used in both experiments and simulations. However, for most practical applications, liquid fuels will have to be considered. Previously, we have presented some preliminary results on multiphase detonations in tubes. In this talk, we will present simulations of the single-cycle performance of PDEs operating on JP10-Oxygen and JP10-Air mixtures. Results for a range of fuel droplet sizes, as well as results when some of the fuel is prevaporized will be presented. The implications of these results on the development and potential application of the PDE will also be discussed.

Kailasanath, K.

2005-11-01

123

16th Australasian Fluid Mechanics Conference: An Evaluation of Computational Fluid Dynamics for Spillway Modelling  

Microsoft Academic Search

Computational Fluid Dynamics (CFD) is used extensively by engineers to model and analyse complex issues related to hydraulic design, planning studies for future generating stations, civil maintenance, supply efficiency, and dam safety. The integrity of computed values from CFD models is of considerable economic importance in the design, upgrading and maintenance of hydroelectric generating stations. CFD models have the ability

P. G. Chanel; J. C. Doering

124

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

ERIC Educational Resources Information Center

|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…

Franklin, Hugh Lockwood, Comp.

125

Scalable, inquiry-based, multimodal modules for Engineering Mechanics curriculum  

Microsoft Academic Search

Students struggle to conceptualize Engineering Mechanics fundamentals because they cannot successfully visualize or intuitively comprehend the effects of external loads on mechanisms. Traditionally, Engineering Mechanics courses have been primarily lecture-based with little experimentation. The authors contend that through the use of scalable, inquiry-based, mutimodal modules, lower-division engineering students can more effectively interpret Engineering Mechanics concepts. An emphasis should be placed

Javier A. Kypuros; Constantine Tarawneh

2008-01-01

126

A fluid-mechanical sewing machine  

NASA Astrophysics Data System (ADS)

It is a breakfast-table experience that when a viscous fluid thread falls a sufficient height onto a stationary horizontal surface the thread is undergoes a coiling instability. We describe experimental observations of a viscous thread falling onto a steadily moving horizontal belt. Low (or zero) belt speeds produce coiling as expected. High belt speeds produce a steady thread, whose shape is well-predicted by theory for a stretching catenary with surface tension and inertia. Intermediate belt speeds show various modes of oscillation, which produce a variety of `stitching' patterns on the belt. The onset of oscillations is predicted theoretically.

Lister, John; Chiu-Webster, Sunny

2004-11-01

127

Fluid Mechanical Modelling of Carbon Dioxide Sequestration  

NASA Astrophysics Data System (ADS)

The flow of supercritical carbon dioxide against an impermeable caprock will be considered from a theoretical and experimental point of view. A series of fundamental problems will be presented, along with some laboratory simulations. It will be shown that in the simplest case, when the caprock is totally impermeable and horizontal, with viscosity differences between the supercritical carbon dioxide and the fluid into which it is intruding neglected, the radius of the spreading of carbon dioxide increases like the square root of time. We will then consider the influence of a sloping caprock, where for time short compared to some critical time, ?c, the spreading pool is close to axisymmetric, while for times very much greater than ?c it is approximately three times larger in the upslope than cross-slope direction. For typical geological conditions, ?c can vary from between days and years, and hence the observed shape will depend on details at the injection site. A discussion of the effects of different viscosities of the intruding and intruded fluid will be presented and the important non- dimensional physical parameters outlined. The talk will conclude with a discussion of very recent research on the effects of heterogeneous porosity in the ambient and an application of the results to the analysis of the observations at Sleipner. The talk will be illustrated by colour movie sequences of experiments and a real desk- top experiment.

Huppert, H. E.

2007-12-01

128

46 CFR 12.15-13 - Deck engine mechanic.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13...Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC...

2010-10-01

129

46 CFR 12.15-13 - Deck engine mechanic.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13...Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC...

2012-10-01

130

46 CFR 12.15-13 - Deck engine mechanic.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13...Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC...

2011-10-01

131

46 CFR 12.15-13 - Deck engine mechanic.  

Code of Federal Regulations, 2010 CFR

... 2009-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13...Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC...

2009-10-01

132

Innovations in Freshman Mechanical Engineering Curriculum at NJIT  

Microsoft Academic Search

This paper describes the Mechanical Engineering contents of a new inter-disciplinary, project-based freshman engineering curriculum at NJIT. The course, which was run as a pilot during the 1996-97 academic year, is called Fundamentals of Engineering and has been now been approved for the freshman engineering curriculum. The two case-study projects, which constitute the Mechanical Engineering component of the course curriculum,

Kwabena A. Narh; Herli Surjanhata

133

Active Learning in Fluid Mechanics: Youtube Tube Flow and Puzzling Fluids Questions  

ERIC Educational Resources Information Center

|Active-learning exercises appropriate for a course in undergraduate fluid mechanics are presented. The first exercise involves an experiment in gravity-driven tube flow, with small groups of students partaking in a contest to predict the experimental flow rates using the mechanical energy balance. The second exercise takes the form of an…

Hrenya, Christine M.

2011-01-01

134

Fluid mechanics in a magnetoplasmadynamic thruster  

Microsoft Academic Search

In this paper both theoretical and experimental results are presented that (1) demonstrate the effects of electrode geometry on the operation of the magnetoplasmadynamic (MPD) arcjet, and (2) describe the 'onset' phenomenon not as a single phenomenon but as two distinct phenomena - the first being related to an anode starvation mechanism and the second arising from full single ionization

D. J. Heimerdinger; M. Martinez-Sanchez

1988-01-01

135

WALL-TO-FLUID TRANSFER MECHANISMS IN BOILING FLOWS  

Microsoft Academic Search

To better understand and predict the boiling flow processes, accurate two-fluid numerical models are needed. One of the important goals of the NURESIM project is to assess and improve the simulation capability of the three-dimensional two-fluid codes for prediction of local boiling flow processes. The boiling flow is strongly affected by local mechanisms in the turbulent boundary layer near the

Mavko Borut

2005-01-01

136

Stirling engine control mechanism and method  

DOEpatents

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.

Dineen, John J. (Durham, NH)

1983-01-01

137

Computational fluid dynamic design of rocket engine pump components  

NASA Astrophysics Data System (ADS)

Integration of computational fluid dynamics (CFD) for design and analysis of turbomachinery components is needed as the requirements of pump performance and reliability become more stringent for the new generation of rocket engine. A fast grid generator, designed specially for centrifugal pump impeller, which allows a turbomachinery designer to use CFD to optimize the component design will be presented. The CFD grid is directly generated from the impeller blade G-H blade coordinates. The grid points are first generated on the meridional plane with the desired clustering near the end walls. This is followed by the marching of grid points from the pressure side of one blade to the suction side of a neighboring blade. This fast grid generator has been used to optimize the consortium pump impeller design. A grid dependency study has been conducted for the consortium pump impeller. Two different grid sizes, one with 10,000 grid points and one with 80,000 grid points were used for the grid dependency study. The effects of grid resolution on the turnaround time, including the grid generation and completion of the CFD analysis, is discussed. The impeller overall mass average performance is compared for different designs. Optimum design is achieved through systematic change of the design parameters. In conclusion, it is demonstrated that CFD can be effectively used not only for flow analysis but also for design and optimization of turbomachinery components.

Chen, Wei-Chung; Prueger, George H.; Chan, Daniel C.; Eastland, Anthony H.

1992-07-01

138

Curriculum policy in Kansai University Departments of Mechanical Engineering  

NASA Astrophysics Data System (ADS)

The concept of educational programs at departments of mechanical engineering in Kansai University is introduced in detail. Furthermore, the outline of the curriculum of the departments of mechanical engineering is explained. The distinctive features of the curriculum, for example; the educational course for freshmen in the mechanical engineering fields, are exemplified. Then, problems in the educational program and original attempts for solving the problems are also described. Under the discussion for reorganization of the faculty of engineering, finally, the plan concerning the innovation in the departments of mechanical engineering would be also introduced.

Arai, Yasuhiko

139

Fluid mechanics in a magnetoplasmadynamic thruster  

NASA Astrophysics Data System (ADS)

In this paper both theoretical and experimental results are presented that (1) demonstrate the effects of electrode geometry on the operation of the magnetoplasmadynamic (MPD) arcjet, and (2) describe the 'onset' phenomenon not as a single phenomenon but as two distinct phenomena - the first being related to an anode starvation mechanism and the second arising from full single ionization in the plasma bulk. Theory and data both show that the electrode current concentrations can be locally changed by varying the channel's interelectrode separation. The experiment (conducted on a large radius annular geometry) and subsequent theory also show a clear separation between an anode depletion description of onset (caused by the radial component of the thrust vector), indicated by the growth of a large anode voltage drop, and the onset indicated by unsteady large amplitude voltage oscillations which are attributed to a global instability of the electrothermal type occurring near full ionization.

Heimerdinger, D. J.; Martinez-Sanchez, M.

140

Notes on the KIVA-2 software and chemically reactive fluid mechanics  

NASA Astrophysics Data System (ADS)

Working notes regarding the mechanics of chemically reactive fluids with sprays, and their numerical simulation with the KIVA-2 software are presented. KIVA-2 is a large FORTRAN program developed at Los Alamos National Laboratory for internal combustion engine simulation. It is our hope that these notes summarize some of the necessary background material in fluid mechanics and combustion, explain the numerical methods currently used in KIVA-2 and similar combustion codes, and provide an outline of the overall structure of KIVA-2 as a representative combustion program, in order to aid the researcher in the task of implementing KIVA-2 or a similar combustion code on a massively parallel computer. The notes are organized into three parts as follows. In Part 1, a brief introduction to continuum mechanics, to fluid mechanics, and to the mechanics of chemically reactive fluids with sprays is presented. In Part 2, a close look at the governing equations of KIVA-2 is taken, and the methods employed in the numerical solution of these equations is discussed. Some conclusions are drawn and some observations are made in Part 3.

Holst, M. J.

1992-09-01

141

Notes on the KIVA-II software and chemically reactive fluid mechanics  

SciTech Connect

This report represents a set of working notes regarding the mechanics of chemically reactive fluids with sprays, and their numerical simulation with the KIVA-II software. KIVA-II is a large FORTRAN program developed at Los Alamos National Laboratory for internal combustion engine simulation. It is our hope is that these notes summarize some of the necessary background material in fluid mechanics and combustion, explain the numerical methods currently used in KIVA-II and similar combustion codes, and provide an outline of the overall structure of KIVA-II as a representative combustion program, in order to aid the researcher in the task of implementing KIVA-II or a similar combustion code on a massively parallel computer. The notes are organized into three parts as follows. In Part I, we give a brief introduction to continuum mechanics, to fluid mechanics, and to the mechanics of chemically reactive fluids with sprays. In Part II, we take a close look at the governing equations of KIVA-II, and discuss the methods employed in the numerical solution of these equations. We draw some conclusions and make some observations in Part III.

Holst, M.J. [Illinois Univ., Urbana, IL (United States). Dept. of Computer Science

1992-09-01

142

Method for starting and operating an advanced regenerative parallel compound dual fluid heat engine-advanced Cheng cycle(ACC)  

Microsoft Academic Search

In a Cheng cycle, dual fluid heat engine of the type is described having: (i) a gas turbine engine including a compressor for compressing a first working fluid, having a compressor outlet, a combustion chamber in fluid communication with the compressor outlet, a turbine unit having an inlet in fluid communication with the combustion chamber for performing work by expansion

1993-01-01

143

FRONT DETAIL OF RIGHT ENGINE AND WING. MECHANICS CHECK METAL ...  

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

FRONT DETAIL OF RIGHT ENGINE AND WING. MECHANICS CHECK METAL CHIP DETECTOR ON RIGHT ENGINE. THE LEADING EDGE FLAPS ON THE RIGHT WING ARE DOWN PRIOR TO LUBRICATION. - Greater Buffalo International Airport, Maintenance Hangar, Buffalo, Erie County, NY

144

Seal mechanism for a Stirling engine  

SciTech Connect

A seal mechanism for a Stirling engine of the type having a displacer piston and a power piston slidably disposed inside a cylinder, the displacer piston having an upper ring groove and a lower ring groove and the power piston having one or more ring grooves, is described comprising: an upper displacer piston ring which is mounted in the upper ring groove; a lower displacer piston ring which is mounted in the lower ring groove; one or more power piston rings, each of which is mounted in one of the ring grooves of the power piston; and means for rendering the seals produced by the upper displacer piston ring and the lower displacer piston ring unidirectional in opposite directions.

Kawajiri, K.; Fujiwara, M.; Nomaguchi, T.; Tsuchino, K.; Kazumoto, Y.

1988-04-12

145

Computer extension of perturbation series in fluid mechanics  

Microsoft Academic Search

A seminumerical computing method is considered. The method makes use of an extension of a perturbation series to high order. The new approach has been applied to a number of problems, mostly in fluid mechanics. Attention is given to the drag coefficient of a sphere according to the Oseen linearization of the Navier-Stokes equations, the subsonic potential flow past a

M. van Dyke

1975-01-01

146

Fluid flow in the osteocyte mechanical environment: a fluid-structure interaction approach.  

PubMed

Osteocytes are believed to be the primary sensor of mechanical stimuli in bone, which orchestrate osteoblasts and osteoclasts to adapt bone structure and composition to meet physiological loading demands. Experimental studies to quantify the mechanical environment surrounding bone cells are challenging, and as such, computational and theoretical approaches have modelled either the solid or fluid environment of osteocytes to predict how these cells are stimulated in vivo. Osteocytes are an elastic cellular structure that deforms in response to the external fluid flow imposed by mechanical loading. This represents a most challenging multi-physics problem in which fluid and solid domains interact, and as such, no previous study has accounted for this complex behaviour. The objective of this study is to employ fluid-structure interaction (FSI) modelling to investigate the complex mechanical environment of osteocytes in vivo. Fluorescent staining of osteocytes was performed in order to visualise their native environment and develop geometrically accurate models of the osteocyte in vivo. By simulating loading levels representative of vigorous physiological activity ([Formula: see text] compression and 300 Pa pressure gradient), we predict average interstitial fluid velocities [Formula: see text] and average maximum shear stresses [Formula: see text] surrounding osteocytes in vivo. Interestingly, these values occur in the canaliculi around the osteocyte cell processes and are within the range of stimuli known to stimulate osteogenic responses by osteoblastic cells in vitro. Significantly our results suggest that the greatest mechanical stimulation of the osteocyte occurs in the cell processes, which, cell culture studies have indicated, is the most mechanosensitive area of the cell. These are the first computational FSI models to simulate the complex multi-physics mechanical environment of osteocyte in vivo and provide a deeper understanding of bone mechanobiology. PMID:23567965

Verbruggen, Stefaan W; Vaughan, Ted J; McNamara, Laoise M

2013-04-01

147

Fluid Assisted Fault Weakening: Mechanical vs. Chemical Processes  

NASA Astrophysics Data System (ADS)

The influx of fluids into fault zones can trigger two main types of weakening process that operate over different timescales, facilitate fault movement and influence fault slip behaviour. During the seismic cycle fluids can be trapped by low permeability fault zones or stratigraphic barriers favoring fluid overpressure (mechanical weakening) and earthquake nucleation. In the entire fault history fluids can react with fault rocks to produce weak mineral phases (chemical weakening) that alter the mechanical properties of the fault zones. Here I will present two examples of mechanical and chemical fault-weakening from the Apennines of Italy. Seismic profiles and deep borehole data show that the strongest earthquakes of the Apennines nucleate within overpressured Evaporites consisting of dolostones and anhydrites. Field and experimental studies on exhumed faults within the same lithology depict a cataclastic inner fault that can generate frictional instabilities with localization and increasing sliding velocity. The outer fault core presents barrier-like portions associated with foliated anhydrites, 10-21 ? permeability ?10-19 m2. The combination of field observations and rock deformation measurements suggests a fault zone structure capable of developing fluid overpressures during the seismic cycle: fluid overpressures can potentially promote earthquake nucleation and aftershock triggering. Field studies from an exhumed regional low-angle normal fault show that in the long term fluids reacted (diffusion-mass transfer processes) with fine-grained cataclasites in the fault core to produce a phyllosilicates-rich and foliated fault rock. Within the foliated microstructure, that is rich in talc, smectite and chlorite, deformation occurs by frictional sliding along 50-200-nm-thick lamellae. Rock deformation experiments show that the foliated fault rock is weak, 0.2 < friction< 0.35, it is characterized by a stable sliding slip-behaviour with no strength recovery with time. Chemical weakening associated with phyllosilicate development along fault zones represents a valuable explanation for long term weak and creeping faults. The activation of mechanical or chemical weakening processes is primarily controlled by pressure, temperature, strain-rate, protolith composition and type of fluids. The interplay between mechanical and chemical weakening favors the development of heterogeneous crustal scale faults that can contribute to explain the complex fault slip behaviour recently documented by high-resolution GPS and seismological data.

Collettini, C.

2011-12-01

148

Bilateral Patching in Retinal Detachment: Fluid Mechanics and Retinal "Settling"  

PubMed Central

Purpose. When a patient suffers a retinal detachment and surgery is delayed, it is known clinically that bilaterally patching the patient may allow the retina to partially reattach or “settle.” Although this procedure has been performed since the 1860s, there is still debate as to how such a maneuver facilitates the reattachment of the retina. Methods. Finite element calculations using commercially available analysis software are used to elucidate the influence of reduction in eye movement caused by bilateral patching on the flow of subretinal fluid in a physical model of retinal detachment. Results. It was found that by coupling fluid mechanics with structural mechanics, a physically consistent explanation of increased retinal detachment with eye movements can be found in the case of traction on the retinal hole. Large eye movements increase vitreous traction and detachment forces on the edge of the retinal hole, creating a subretinal vacuum and facilitating increased subretinal fluid. Alternative models, in which intraocular fluid flow is redirected into the subretinal space, are not consistent with these simulations. Conclusions. The results of these simulations explain the physical principles behind bilateral patching and provide insight that can be used clinically. In particular, as is known clinically, bilateral patching may facilitate a decrease in the height of a retinal detachment. The results described here provide a description of a physical mechanism underlying this technique. The findings of this study may aid in deciding whether to bilaterally patch patients and in counseling patients on pre- and postoperative care.

2011-01-01

149

Micro-CAE mechanical engineering software development  

Microsoft Academic Search

A concept in Microcomputer-Aided Engineering has been evolving and maturing at Lawrence Livermore National Laboratory during the past 4 years. In harmony with the goals of the project, several universities are participating in the development of software which will be useful both to engineering colleges and to practicing engineers. Among the universities who have had faculty participants in this project

W. Comfort; B. Davis

1985-01-01

150

Effects of fluid flow on the in vitro degradation kinetics of biodegradable scaffolds for tissue engineering  

Microsoft Academic Search

Scaffolds fabricated from biodegradable polymers are used extensively in the field of tissue engineering. Many of these scaffolds are subjected to fluid flow, either in vivo or in bioreactors ex vivo. The goal of this study was to examine the effects of fluid flow on the degradation characteristics and kinetics of scaffolds in vitro. Scaffolds with different porosity and permeability

C. M Agrawal; J. S McKinney; D Lanctot; K. A Athanasiou

2000-01-01

151

Drilling Fluid Considerations in Design of Engineered Horizontal Directional Drilling Installations  

Microsoft Academic Search

A literature review is presented that identifies a number of areas where procedures for the engineering design of bored installations in soil using horizontal directional drilling HDD can be improved through a more realistic consideration of drilling fluid drag effects and skin friction coefficients. The current HDD practice of calculating annular frictional pressure loss caused by drilling fluid drag based

Michael E. Baumert; Erez N. Allouche; Ian D. Moore

2005-01-01

152

Trends in the Education and Training of Professional Mechanical Engineers.  

ERIC Educational Resources Information Center

|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,…

Institution of Mechanical Engineers, London (England).

153

A Sequential Fluid-mechanic Chemical-kinetic Model of Propane HCCI Combustion  

SciTech Connect

We have developed a methodology for predicting combustion and emissions in a Homogeneous Charge Compression Ignition (HCCI) Engine. This methodology combines a detailed fluid mechanics code with a detailed chemical kinetics code. Instead of directly linking the two codes, which would require an extremely long computational time, the methodology consists of first running the fluid mechanics code to obtain temperature profiles as a function of time. These temperature profiles are then used as input to a multi-zone chemical kinetics code. The advantage of this procedure is that a small number of zones (10) is enough to obtain accurate results. This procedure achieves the benefits of linking the fluid mechanics and the chemical kinetics codes with a great reduction in the computational effort, to a level that can be handled with current computers. The success of this procedure is in large part a consequence of the fact that for much of the compression stroke the chemistry is inactive and thus has little influence on fluid mechanics and heat transfer. Then, when chemistry is active, combustion is rather sudden, leaving little time for interaction between chemistry and fluid mixing and heat transfer. This sequential methodology has been capable of explaining the main characteristics of HCCI combustion that have been observed in experiments. In this paper, we use our model to explore an HCCI engine running on propane. The paper compares experimental and numerical pressure traces, heat release rates, and hydrocarbon and carbon monoxide emissions. The results show an excellent agreement, even in parameters that are difficult to predict, such as chemical heat release rates. Carbon monoxide emissions are reasonably well predicted, even though it is intrinsically difficult to make good predictions of CO emissions in HCCI engines. The paper includes a sensitivity study on the effect of the heat transfer correlation on the results of the analysis. Importantly, the paper also shows a numerical study on how parameters such as swirl rate, crevices and ceramic walls could help in reducing HC and CO emissions from HCCI engines.

Aceves, S M; Flowers, D L; Martinez-Frias, J; Smith, J R; Westbrook, C; Pitz, W; Dibble, R; Wright, J F; Akinyemi, W C; Hessel, R P

2000-11-29

154

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

Code of Federal Regulations, 2010 CFR

...2009-10-01 false Mechanical engine order telegraph...CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND... § 113.35-15 Mechanical engine order telegraph...application. If a mechanical engine order...

2009-10-01

155

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

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Mechanical engine order telegraph...CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND... § 113.35-15 Mechanical engine order telegraph...application. If a mechanical engine order...

2010-10-01

156

Characterization of the Mechanical Properties of Electrorheological Fluids Made of Starch and Silicone Fluid  

NASA Astrophysics Data System (ADS)

In the majority of published articles on the topic, ER fluids have been studied as if they were viscous liquids. In this work, electrorheological fluids were characterized as solids and their mechanical properties were determined. The results infer that ER materials are controllably resistant to compression, tensile and shear stress, in this order of magnitude. More precisely, fluids made of starch have elasticity modulus similar to that of rubber, they have tensile strength 103 to 5×104 times lower than that of low density polyethylene (LDPE), static yield stress 4×104 to 8×105 times lower than that of acrylonitrile-butadiene-styrene terpolymer (ABS) and fatigue life similar to some polymers like polyethylene(PE) and polypropylene (PP).

Vieira, Sheila Lopes; de Arruda, Antonio Celso Fonseca

157

Fluid coupling in a discrete model of cochlear mechanics.  

PubMed

A discrete model of cochlear mechanics is introduced that includes a full, three-dimensional, description of fluid coupling. This formulation allows the fluid coupling and basilar membrane dynamics to be analyzed separately and then coupled together with a simple piece of linear algebra. The fluid coupling is initially analyzed using a wavenumber formulation and is separated into one component due to one-dimensional fluid coupling and one comprising all the other contributions. Using the theory of acoustic waves in a duct, however, these two components of the pressure can also be associated with a far field, due to the plane wave, and a near field, due to the evanescent, higher order, modes. The near field components are then seen as one of a number of sources of additional longitudinal coupling in the cochlea. The effects of non-uniformity and asymmetry in the fluid chamber areas can also be taken into account, to predict both the pressure difference between the chambers and the mean pressure. This allows the calculation, for example, of the effect of a short cochlear implant on the coupled response of the cochlea. PMID:21895085

Elliott, Stephen J; Lineton, Ben; Ni, Guangjian

2011-09-01

158

Acoustics in mechanical engineering undergraduate core courses: Challenges and opportunities  

Microsoft Academic Search

Generally in an undergraduate curriculum of mechanical engineering, acoustics is not included as a core course. The major core courses deal with mechanics, design, dynamics of machinery, etc. However, engineering aspects of acoustics or noise can be included through elective courses. Given the limited slots for elective courses in a curriculum, it is difficult to run elective courses in acoustics

M. G. Prasad

2005-01-01

159

Experimental Fluid Mechanics of Pulsatile Artificial Blood Pumps  

NASA Astrophysics Data System (ADS)

The fluid mechanics of artificial blood pumps has been studied since the early 1970s in an attempt to understand and mitigate hemolysis and thrombus formation by the device. Pulsatile pumps are characterized by inlet jets that set up a rotational "washing" pattern during filling. Strong regurgitant jets through the closed artificial heart valves have Reynolds stresses on the order of 10,000 dynes/cm2 and are the most likely cause of red blood cell damage and platelet activation. Although the flow in the pump chamber appears benign, low wall shear stresses throughout the pump cycle can lead to thrombus formation at the wall of the smaller pumps (10 50 cc). The local fluid mechanics is critical. There is a need to rapidly measure or calculate the wall shear stress throughout the device so that the results may be easily incorporated into the design process.

Deutsch, Steven; Tarbell, John M.; Manning, Keefe B.; Rosenberg, Gerson; Fontaine, Arnold A.

2006-01-01

160

Micro-Electro-Mechanical-Systems (MEMS) and Fluid Flows  

Microsoft Academic Search

The micromachining technology that emerged in the late 1980s can provide micron-sized sensors and actuators. These micro transducers are able to be integrated with signal conditioning and processing circuitry to form micro-electro-mechanical-systems (MEMS) that can perform real-time distributed control. This capability opens up a new territory for flow control research. On the other hand, surface effects dominate the fluid flowing

Chih-Ming Ho; Yu-Chong Tai

1998-01-01

161

Comparison of Differing Credit Hour Allotments for Thermodynamics and Fluid Mechanics Courses  

NSDL National Science Digital Library

Each institution determines how many credit hours will be allotted for each course. Thermodynamics and fluid mechanics in an undergraduate Bachelor of Science Mechanical Engineering curriculum in the United States typically are allotted three or four credit hours. For a semester system, this allows for 42-45 or 56-60 fifty-minute class sessions in three and four credit hour courses, respectively. Opinions vary whether thermodynamics and fluid mechanics should each be three credit hours, each be four credit hours, or one should be three and the other four. Two universities have conducted a study to determine the advantages, disadvantages, and consequences of three vs. four credit hours. One university has a four credit hour thermodynamics and a three credit hour fluid mechanics, while the other university has exactly the opposite. Through student surveys, course objectives/outcomes, course syllabi, instructors experiences, and average grades, conclusions are drawn on the effects of course length. Other issues are examined such as challenges facing instructors who have previously taught a four credit hour course that now must cover the same material within a three credit hour allotment. Finally recommendations are given for instructors that are allotted less than desirable credit hours.

Fletcher, Robert; Gerhart, Andrew; Gerhart, Philip

2011-05-06

162

Fluid mechanics of eating, swallowing and digestion - overview and perspectives.  

PubMed

From a very simplistic viewpoint, the human digestive system can be regarded as a long tube (with dramatic variations in diameter, cross-section, wall properties, pumping mechanisms, regulating valves and in-line sensors). We single out a few fluid mechanical phenomena along the trajectory of a food bolus from the mouth to the small intestine and discuss how they influence sensorial perception, safe transport, and nutrient absorption from a bolus. The focus is on lubrication flows between the tongue and palate, the oropharyngeal stage of swallowing and effects of flow on absorption in the small intestine. Specific challenges and opportunities in this research area are highlighted. PMID:23233019

Engmann, Jan; Burbidge, Adam S

2013-02-26

163

Shift mechanism for engine starting apparatus  

SciTech Connect

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.

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

1986-04-01

164

Development of Engineering Design Education in the Department of Mechanical Engineering at Kanazawa Technical College  

NASA Astrophysics Data System (ADS)

This paper introduces a method of the engineering design education for college of technology mechanical engineering students. In order to teach the practical engineering design, the MIL-STD-499A process is adapted and improved upon for a Mechatronics hands-on lesson used as the MOT method. The educational results in five years indicate that knowledge of the engineering management is useful for college students in learning engineering design. Portfolio for lessons and the hypothesis method also have better effects on the understanding of the engineering specialty.

Yamada, Hirofumi; Ten-Nichi, Michio; Mathui, Hirosi; Nakamura, Akizi

165

Vector Mechanics for Engineers: Statics and Dynamics  

NSDL National Science Digital Library

This textbook website has resources for instructors and students using the text, including supplemental material and some solutions. It also has general interest materials for engineering and science students and instructors.

Beer, Ferdinand; E. Russell, Jr. J.; Eisenberg, Elliot; Sarubbi, Robert

2003-12-05

166

Study of Erosion Mechanisms of Engineering Ceramics.  

National Technical Information Service (NTIS)

Four 'engineering' ceramics were subjected to impact (single particle) and erosion (multiple impacts) under conditions which simulate a natural dust environment in the subsonic velocity regime. The target materials are hot pressed Si3N4, reaction bonded S...

M. E. Gulden

1977-01-01

167

Role of cells in freezing-induced cell-fluid-matrix interactions within engineered tissues.  

PubMed

During cryopreservation, ice forms in the extracellular space resulting in freezing-induced deformation of the tissue, which can be detrimental to the extracellular matrix (ECM) microstructure. Meanwhile, cells dehydrate through an osmotically driven process as the intracellular water is transported to the extracellular space, increasing the volume of fluid for freezing. Therefore, this study examines the effects of cellular presence on tissue deformation and investigates the significance of intracellular water transport and cell-ECM interactions in freezing-induced cell-fluid-matrix interactions. Freezing-induced deformation characteristics were examined through cell image deformetry (CID) measurements of collagenous engineered tissues embedded with different concentrations of MCF7 breast cancer cells versus microspheres as their osmotically inactive counterparts. Additionally, the development of a biophysical model relates the freezing-induced expansion of the tissue due to the cellular water transport and the extracellular freezing thermodynamics for further verification. The magnitude of the freezing-induced dilatation was found to be not affected by the cellular water transport for the cell concentrations considered; however, the deformation patterns for different cell concentrations were different suggesting that cell-matrix interactions may have an effect. It was, therefore, determined that intracellular water transport during freezing was insignificant at the current experimental cell concentrations; however, it may be significant at concentrations similar to native tissue. Finally, the cell-matrix interactions provided mechanical support on the ECM to minimize the expansion regions in the tissues during freezing. PMID:23719856

Seawright, Angela; Ozcelikkale, Altug; Dutton, Craig; Han, Bumsoo

2013-09-01

168

Mechanical Properties and Compositions of Tissue Engineered and Native Arteries  

PubMed Central

With the goal of mimicking the mechanical properties of a given native tissue, tissue engineers seek to culture replacement tissues with compositions similar to those of native tissues. In this report, differences between the mechanical properties of engineered arteries and native arteries were correlated with differences in tissue composition. Engineered arteries failed to match the strengths or compliances of native tissues. Lower strengths of engineered arteries resulted partially from inferior organization of collagen, but not from differences in collagen density. Furthermore, ultimate strengths of engineered vessels were significantly reduced by the presence of residual polyglycolic acid polymer fragments, which caused stress concentrations in the vessel wall. Lower compliances of engineered vessels resulted from minimal smooth muscle cell contractility and a lack of organized extracellular elastin. Organization of elastin and collagen in engineered arteries may have been partially hindered by high concentrations of sulfated glycosaminoglycans. Tissue engineers should continue to regulate cell phenotype and promote synthesis of proteins that are known to dominate the mechanical properties of the associated native tissue. However, we should also be aware of the potential negative impacts of polymer fragments and glycosaminoglycans on the mechanical properties of engineered tissues.

Dahl, Shannon L. M.; Rhim, Caroline; Song, Ying C.; Niklason, Laura E.

2008-01-01

169

Numerical Investigations on the Thrust Augmentation Mechanisms of Ejectors Driven by Pulse Detonation Engines  

Microsoft Academic Search

Numerical simulations of a single ejector driven by one- and two-pulse detonation engines (PDE) were performed to investigate the thrust augmentation mechanism. The systems of conservative laws of inviscid fluid combined with the one-step chemical reaction model are discretized in Cartesian coordinates using the high resolution hybrid Roe\\/HLL scheme and adaptive mesh refinement method, and integration in time is performed

Huan-hao Zhang; Zhi-hua Chen; Xiao-hui Sun; Xiao-hai Jiang; Bao-ming Li

2011-01-01

170

Aerofoil flutter: fluid-mechanical analysis and wind tunnel testing  

NASA Astrophysics Data System (ADS)

This paper describes a three dimensional wing model, which has been developed for the purpose of studying flutter, both computationally and through wind tunnel testing. A three dimensional, laminar flow aerofoil wing, based on the NACA aerofoil has been designed. The natural frequencies for this aerofoil were obtained through modal analysis. A scale model wing, without taper was manufactured in the laboratory and tested in a wind tunnel. The pressure data was obtained from fluid flow analysis and the deformation results obtained through structural analysis. The analysis was performed in the ANSYS Workbench Environment, accessing FLUENT CFX for the computational fluid dynamics analysis and the ANSYS FEA package for the mechanical analysis. The computational results obtained are compared with the experimental data obtained in the wind tunnel. Comparison of the analysis and test results provides further understanding of the flutter characteristics.

Wensuslaus, A. L.; McMillan, A. J.

2012-08-01

171

Application of Computational Fluid Dynamics in building services engineering  

Microsoft Academic Search

Application of Computational Fluid Dynamics to building services design is illustrated and reviewed. Principal areas of application are designs requiring an understanding of the air flow pattern, such as design of smoke control systems and air distribution in a heating, ventilation and air-conditioning system. In such an approach, the indoor air motion is described by a set of partial differential

W. K. Chow

1996-01-01

172

Encyclopedia of fluid mechanics. Volume 8 - Aerodynamics and compressible flows  

NASA Astrophysics Data System (ADS)

Advanced analytical methods for compressible flows and their application to specific engineering problems are discussed in chapters by leading experts. Topics addressed include fluid viscosity, laminar flow past semiinfinite bodies, the structure of turbulent boundary layers, homogeneous turbulence, turbulent shear flows and jets, vortex patterns on slender bodies, wake interference and vortex shedding, turbulent rough-wall skin friction and heat transfer, FEM iterative solutions of compressible flows, transient natural-convection flows, and direct-contact transfer processes with moving liquid droplets. Consideration is given to artificially thickening turbulent boundary layers, subsonic transitory stalled flows in diffusers, impeller-blade design for centrifugal and axial blowers, transonic cascade flows, high-speed turboprop noise, turbine-blade vibrations, compressible flow in valves, the performance of cryogenic pumps, the structure of turbulent dense-spray jets, and the dynamics of wind machines.

Cheremisinoff, Nicholas P.

173

The Fluid Mechanics of Cancer and Its Therapy  

NASA Astrophysics Data System (ADS)

Fluid mechanics is involved in the growth, progression, metastasis, and therapy of cancer. Blood vessels transport oxygen and nutrients to cancerous tissues, provide a route for metastasizing cancer cells to distant organs, and deliver drugs to tumors. The irregular and leaky tumor vasculature is responsible for increased interstitial pressure in the tumor microenvironment, whereas multiscale flow-structure interaction processes control tumor growth, metastasis, and nanoparticle-mediated drug delivery. We outline these flow-mediated processes, along with related experimental and computational methods for the diagnosis, predictive modeling, and therapy of cancer.

Koumoutsakos, Petros; Pivkin, Igor; Milde, Florian

2013-01-01

174

The Role of Industry in the Education of Mechanical Engineers.  

ERIC Educational Resources Information Center

Explains how industry contacts are developed for mechanical engineering students at the Catholic University at Leuven, Belgium. Describes their aims, working conditions, results and the role of research. Discusses the importance of industry contacts in the education of future engineers. (CW)

Gobin, R.

1987-01-01

175

Project Driven Curriculum in the Mechanical Engineering Technology Program  

Microsoft Academic Search

The authors of this paper have incorporated a project driven approach into teaching engineering technology courses in the Mechanical Engineering Technology program at Penn State Hazleton. During the last five years, two projects were introduced and incorporated into the MET curriculum. The first project was to design and build a full-scale two seat experimental aircraft. The second project was a

JungHun Choi; Wes Grebski; Hazleton Hazleton

176

Valve timing and valve lift control mechanism for engines  

Microsoft Academic Search

A new type engine valve control system has been presented, in which both the valve lift and valve timing are controlled directly by electric motors. A mechanism of the valve timing control system is made of planetary gears. The outer gear is the timing pulley which has a timing belt driven by the crankshaft of an engine. Two planetary gears

Kosuke Nagaya; Hiroyuki Kobayashi; Kazuya Koike

2006-01-01

177

The role of computational fluid dynamics in aeronautical engineering  

NASA Astrophysics Data System (ADS)

Numerical analyses by solving Euler/Navier-Stokes Equations has been used in practical aeronautical engineerings. Here, the results of two dimensional Navier-Stokes analyses of a multiple slotted flap, and a three dimensional wing design problem using Euler analyses are shown.

Kishimoto, Takuji; Uchida, Takashi

1988-12-01

178

The role of computational fluid dynamics in aeronautical engineering  

Microsoft Academic Search

Numerical analyses by solving Euler\\/Navier-Stokes Equations has been used in practical aeronautical engineerings. Here, the results of two dimensional Navier-Stokes analyses of a multiple slotted flap, and a three dimensional wing design problem using Euler analyses are shown.

Takuji Kishimoto; Takashi Uchida

1988-01-01

179

Mathematical Building-Blocks in Engineering Mechanics  

ERIC Educational Resources Information Center

|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…

Boyajian, David M.

2007-01-01

180

Oil oxidation mechanism in piston engines  

Microsoft Academic Search

Many attempts have been made to establish the sources of composition change in the used crankcase oil and to determine the engine zone in which the severely oxidized products are formed. Laboratory tests have demonstrated the possibility of contamination of crankcase oil with products formed at temperatures of 200250~ on the walls of the piston ring grooves [3]. Ventsel' [4

A. V. Nepogod'ev

1977-01-01

181

Marine Engine Mechanics. Performance Objectives. Basic Course.  

ERIC Educational Resources Information Center

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…

Jones, Marion

182

Mathematical Building-Blocks in Engineering Mechanics  

ERIC Educational Resources Information Center

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…

Boyajian, David M.

2007-01-01

183

19. VIEW OF ENGINE HOUSE INTERIOR, SHOWING CABLE MECHANISM (FLYWHEEL, ...  

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

19. VIEW OF ENGINE HOUSE INTERIOR, SHOWING CABLE MECHANISM (FLYWHEEL, GEAR, CABLE DRUM, LOCATOR DIAL), LOOKING EAST - Delaware, Lackawanna & Western Railroad, Pier No. 6, Erie Lackawanna Railroad Yard, Jersey City, Hudson County, NJ

184

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

185

Computer-Aided Engineering Environment for Controlled Mechanical Systems.  

National Technical Information Service (NTIS)

A computer-aided engineering environment for the design and analysis of computer controlled mechanical systems is defined, and a prototype environment is demonstrated. The overall integrated environment includes systems for 3D geometric modeling and anima...

K. C. Craig M. Mattice P. N. Sheth S. Banks

1990-01-01

186

Appplication of a general fluid mechanics program to NTP system modeling  

NASA Astrophysics Data System (ADS)

An effort is currently underway at NASA and the Department of Energy (DOE) to develop an accurate model for predicting nuclear thermal propulsion (NTP) system performance. The objective of the effort is to develop several levels of computer programs which vary in detail and complexity according to user's needs. The current focus is on the Level 1 steady-state, parametric system model. This system model will combine a general fluid mechanics program, SAFSIM, with the ability to analyze turbines, pumps, nozzles, and reactor physics. SAFSIM (System Analysis Flow SIMulator) is a FORTRAN computer program that simulates integrated performance of systems involving fluid mechanics, heat transfer, and reactor dynamics. SAFSIM has the versatility to allow simulation of almost any system, including a nuclear reactor system. The focus of this paper is the validation of SAFSIM's capabilities as a base computational engine for a nuclear thermal propulsion system model. Validation is being accomplished by modeling of a nuclear engine test using SAFSIM and comparing the results to known experimental data. For this study, the NRX/EST test was chosen; it was the first of the tests to demonstrate the integration of all system components (including the turbopump) and it utilized the hot bleed cycle. This paper present a comparison of analytical results with experimental system performance in terms of state points, mass flow rates, wall temperatures, and specific impulse. In addition, the methodology used in the validation efforts will be discussed.

Lee, Stacey K.

1993-01-01

187

The role of computational fluid dynamics in aeronautical engineering  

Microsoft Academic Search

The task of aircraft design often favors a robust, low-cost computational method rather than a sophisticated one. Examples of such engineering methods currently in use are described in this paper. Included are a viscous-inviscid coupling procedure for a 2-D airfoil at high angle of attack in incompressible flow, a vortex-lattice procedure for not-so-slender wings, and extensions of the FLO22 code

T. Uchida; T. Jyonouchi; K. Sawada; T. Nohisa

1984-01-01

188

Mechanical Diagnostics System Engineering in IMD HUMS  

Microsoft Academic Search

The Goodrich Integrated Mechanical Diagnostics Health and Usage System (IMD-HUMS) mechanical diagnostics functionality is the integration of disparate subsystems. When the aircraft is in the appropriate capture window, the primary processing unit (PPU), commands the vibration processing unit (VPU) to capture vibration data and a tachometer reference. This time domain data is processed by standard and proprietary algorithms to generate

Eric Bechhoefer; Eric Mayhew

2006-01-01

189

The Study Program in the Education of Mining Engineering - Mechanical Engineering  

Microsoft Academic Search

The article suggests the teaching plan of mechanical engineering subjects for the education of mining engineers. This part of study is divided into six subjects included in the 4th, 5th, 6th and 7th semesters. Main emphasis is placed on the understanding of principles of mining machines, their operating conditions, technology and safety of their use and economical problems. Possible syllabuses

Jaromir Polak

190

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

ERIC Educational Resources Information Center

|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…

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

2013-01-01

191

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

ERIC Educational Resources Information Center

|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…

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

192

Fast Prediction of HCCI Combustion with an Artificial Neural Network Linked to a Fluid Mechanics Code  

SciTech Connect

We have developed an artificial neural network (ANN) based combustion model and have integrated it into a fluid mechanics code (KIVA3V) to produce a new analysis tool (titled KIVA3V-ANN) that can yield accurate HCCI predictions at very low computational cost. The neural network predicts ignition delay as a function of operating parameters (temperature, pressure, equivalence ratio and residual gas fraction). KIVA3V-ANN keeps track of the time history of the ignition delay during the engine cycle to evaluate the ignition integral and predict ignition for each computational cell. After a cell ignites, chemistry becomes active, and a two-step chemical kinetic mechanism predicts composition and heat generation in the ignited cells. KIVA3V-ANN has been validated by comparison with isooctane HCCI experiments in two different engines. The neural network provides reasonable predictions for HCCI combustion and emissions that, although typically not as good as obtained with the more physically representative multi-zone model, are obtained at a much reduced computational cost. KIVA3V-ANN can perform reasonably accurate HCCI calculations while requiring only 10% more computational effort than a motored KIVA3V run. It is therefore considered a valuable tool for evaluation of engine maps or other performance analysis tasks requiring multiple individual runs.

Aceves, S M; Flowers, D L; Chen, J; Babaimopoulos, A

2006-08-29

193

Computational thermal, chemical, fluid, and solid mechanics for geosystems management.  

SciTech Connect

This document summarizes research performed under the SNL LDRD entitled - Computational Mechanics for Geosystems Management to Support the Energy and Natural Resources Mission. The main accomplishment was development of a foundational SNL capability for computational thermal, chemical, fluid, and solid mechanics analysis of geosystems. The code was developed within the SNL Sierra software system. This report summarizes the capabilities of the simulation code and the supporting research and development conducted under this LDRD. The main goal of this project was the development of a foundational capability for coupled thermal, hydrological, mechanical, chemical (THMC) simulation of heterogeneous geosystems utilizing massively parallel processing. To solve these complex issues, this project integrated research in numerical mathematics and algorithms for chemically reactive multiphase systems with computer science research in adaptive coupled solution control and framework architecture. This report summarizes and demonstrates the capabilities that were developed together with the supporting research underlying the models. Key accomplishments are: (1) General capability for modeling nonisothermal, multiphase, multicomponent flow in heterogeneous porous geologic materials; (2) General capability to model multiphase reactive transport of species in heterogeneous porous media; (3) Constitutive models for describing real, general geomaterials under multiphase conditions utilizing laboratory data; (4) General capability to couple nonisothermal reactive flow with geomechanics (THMC); (5) Phase behavior thermodynamics for the CO2-H2O-NaCl system. General implementation enables modeling of other fluid mixtures. Adaptive look-up tables enable thermodynamic capability to other simulators; (6) Capability for statistical modeling of heterogeneity in geologic materials; and (7) Simulator utilizes unstructured grids on parallel processing computers.

Davison, Scott; Alger, Nicholas; Turner, Daniel Zack; Subia, Samuel Ramirez; Carnes, Brian; Martinez, Mario J.; Notz, Patrick K.; Klise, Katherine A.; Stone, Charles Michael; Field, Richard V., Jr.; Newell, Pania; Jove-Colon, Carlos F.; Red-Horse, John Robert; Bishop, Joseph E.; Dewers, Thomas A.; Hopkins, Polly L.; Mesh, Mikhail; Bean, James E.; Moffat, Harry K.; Yoon, Hongkyu

2011-09-01

194

Superhydrophobic surface as a fluid enhancement material in engineering applications  

NASA Astrophysics Data System (ADS)

In this study, a superhydrophobic surface and its relation to the enhancement of the droplet fluid dynamics to the surface of the object materials was investigated. As the comparison, hydrophilic and uncoated surface of an object also investigated. The investigations used height of impact at 89 mm. The high quality speed camera is employed to investigate the droplet dynamic on a copper foil and a calcium fluoride surfaces. Both of the materials are coated with superhydrophobic and hydrophilic surfaces separately. The droplet diameter was analyzed using the program PHANTOM. The droplet contact angle was analyzed by the Goniometry method. The water was dropped on the calcium fluoride and the copper foil using a syringe (sharp tip) with initial droplet diameter of 1.9 mm. To record the droplet fluid shape, the photo micro sensor was placed inside the trigger box below the syringe. The results showed that the superhydrophobic surface both on copper foil and calcium fluoride enhanced the mobility of a droplet compared to the hydrophilic and the uncoated surfaces. The results showed that the maximum droplet diameter on the copper foil coated by the superhydrophobic, the hydrophilic and the uncoated surfaces are 4.7, 5.0, 5.2 mm, respectively; and for the calcium fluoride are 4.5, 5.1 and 5.5 mm, respectively. Meanwhile, the results for the droplet contact angle on the copper foil coated by the superhydrophobic, the hydrophilic and the uncoated surfaces are 20°, 90°, 160°, respectively; and for the calcium fluoride are 25°, 95°, 165°, respectively.

Tetuko, Anggito P.; Khaerudini, Deni S.; Sardjono, Priyo; Sebayang, Perdamean; Rosengarten, Gary

2013-09-01

195

Lacunocanalicular fluid flow transduces mechanical tension stress during distraction osteogenesis.  

PubMed

The mechanotransduction mechanisms linking distraction device activation to new bone formation remain unknown. We hypothesize that the tension stress of activation during distraction osteogenesis is transmitted through lacunocanalicular fluid flow to initiate the osteogenic signaling cascade. Adult Sprague-Dawley rats (N = 24) were subjected to mandibular osteotomy and application of an external distraction device. After a 3-day latency period, half the animals (n = 12) underwent device activation at 0.25 mm twice daily for 6 days (total activation, 3 mm), and the other half (n = 12) had no activation. On day 10, the animals were injected with fluorescent reactive red lacunocanalicular tracer before killing. Mandibles were harvested, embedded, and sectioned, and reactive red epifluorescence lacunocanalicular flow was measured. Protein was harvested for focal adhesion kinase 1 (FAK1), NESPRIN1, SUN1, LAMIN A/C, and SMAD1 Western blotting as well as for bone morphogenetic protein (BMP)-2 enzyme-linked immunosorbent assay and alkaline phosphatase assay. Lacunocanalicular fluid flow was significantly greater in the distracted samples (60.5 ± 14 vs 10.3 ± 4 molecules of equivalent soluble fluorochrome per megapixel, P = 0.01). Flow distribution demonstrated the highest lacunocanalicular flow near the center of the distraction gap. Increased lacunocanalicular flow resulted in increased FAK1 (P = 0.009), NESPRIN1 (P = 0.01), SUN1 (P = 0.01), and LAMIN A/C (P = 0.008) expression. Focal adhesion kinase 1 activation in the presence of BMP-2 protein expression (P = 0.001) resulted in increased intranuclear SMAD1 phosphorylation (P = 0.04) and alkaline phosphatase activity (P < 0.0001). These findings suggest that activation of the distraction osteogenesis device affects cellular response through changes in lacunocanalicular fluid flow. PMID:24036726

Davidson, Edward H; Sultan, Steven M; Butalala, Parag; Knobel, Denis; Warren, Stephen M

2013-09-01

196

The Fluid Mechanics of Bonding with Yield Stress Epoxies  

NASA Astrophysics Data System (ADS)

An important component of most microelectronic packages is the silver filled, thermally conductive epoxy, which forms the bond between the microelectronic chip and the metallic substrate called the lead frame. As microelectronic chips become larger, more epoxy is needed to form this bond. This presents two fundamental heat transfer and fluid mechanics problems. (i) The time necessary to form the bond becomes very long even for modest increases in chip size. (ii) Curing the larger volume of epoxy leads to higher concentrations of epoxy volatiles, which can contaminate sensitive chip surfaces. The flow associated with the formation of the epoxy bond has been investigated both analytically and experimentally. Squeezing flow experiments have shown that the epoxy behaves as a yield stress fluid. A variational analysis of the flow reveals that the yield stress nature of the epoxy makes the quick formation of thin bonds difficult. However, further experiments have shown that oscillating the magnitude of the bonding force reduces the apparent yield stress by breaking down the fluid microstructure, and dramatically reduces bonding time. A detailed numerical and experimental analysis of the flow, heat transfer, and mass transfer in an oven used to cure the epoxy is also presented. A control volume numerical analysis shows that condensation and contamination may be best avoided by routing an evacuation flow through the oven so as to maintain the partial pressure of the epoxy vapor below its saturation pressure. The numerical results were validated by a flow visualization study on a 10times upscaled model of a typical curing oven.

Zwick, Kenneth John

197

Prior Knowledge of Mechanics amongst First Year Engineering Students  

ERIC Educational Resources Information Center

|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

Clements, Dick

2007-01-01

198

Dysfunctioning of the Fluid Mechanical Craniospinal Systems as Revealed by Stress/Strain Diagrams.  

National Technical Information Service (NTIS)

The functioning of the two fluid mechanical systems of the brain, the cerebrospinal fluid and cerebral vascular, were related to their pressure levels and outflow control. Information is presented concerning both normal and pathological functioning of the...

K. L. Allen E. A. Bunt

1977-01-01

199

A Math Knowledge Inevitable for Bachelor Engineer, Enlightened Through Teaching at Mechanical Engineering Department  

NASA Astrophysics Data System (ADS)

Inspite efforts of rebirthing engineering education degradation of student achievement is progressing due to several reasons. In particular, introducing accrediting system in each university has actually contributed to improve engineering education. However, math achievement of student having different study path is unclear. Taking into account the math knowledge inevitable for bachelor engineer, present author proposes a concrete desirable math knowledge on differentiation, integral, ordinal and extraordinal differential equation, vector, tensor and complex variables at graduation, derived from his teaching career at department of mechanical engineering.

Harada, Shoji

200

ESSENTIAL HIGHLIGHTS OF THE HISTORY OF FLUID MECHANICS  

Technology Transfer Automated Retrieval System (TEKTRAN)

To achieve accreditation, engineering and technology programs throughout the United States must meet guidelines established by the Accreditation Board for Engineering and Technology (ABET), which require departments to demonstrate that they provide students with an understanding of engineering in a ...

201

Fluid mechanics analysis of a spring-loaded jet injector.  

PubMed

A syringe jet injector is a device designed to administer a drug quickly and painlessly through the skin. Though syringe jet injectors have been in use for almost 50 years, current designs still suffer from inconsistent performance. To better understand the fluid mechanics of jet injection and gain insight into how the design might influence performance, two theoretical analyses to determine the fluid pressure profile at the exit orifice were conducted. The first was a continuum analysis assuming static incompressibility. Results demonstrated that the maximum jet pressure was highly sensitive to the spring constant, initial piston velocity, and piston cross-sectional area while the time to achieve the maximum pressure was most sensitive to the injection chamber length, initial piston velocity, bulk modulus of the injectant, and the piston cross-sectional area. The second analysis was a shock wave analysis. Results demonstrated a stepwise pressure-time plot that was similar in magnitude to that for the continuum analysis assuming static incompressibility. Results from these two investigations are useful for design modification of the jet injector to achieve desired pressure-time profiles at the orifice. Control of pressure-time profiles may help to achieve a more consistent and effective injection process. PMID:9932345

Baker, A B; Sanders, J E

1999-02-01

202

A numerical simulation of mechanical heart valve closure fluid dynamics.  

PubMed

A computational fluid dynamics model for the analysis of the bileaflet mechanical heart valve closure process is presented. The objective of the study is to demonstrate the ability of the numerical model to simulate the leaflet motion during the closing phase in order to investigate the closure fluid dynamics and to evaluate the effect of alterations in the leaflet tip geometry. The model has been applied to six different combinations of the leaflet tip geometry and the gap width between the leaflet tip and the housing. The results show that the negative pressure quickly develops on the atrial side of the leaflet tip. The pressure becomes more negative as the leaflet closure progresses and the lowest pressure is reached before the leaflet comes to a stop in the closed position. The flow dynamics at the instant of valve closure is strongly dependent on the leaflet velocity during the closing phase. Decrease of the tip velocity by a factor of three in the last four degrees of leaflet motion leads to a 50% reduction in the negative pressure magnitude. PMID:12052390

Lai, Yong G; Chandran, Krishnan B; Lemmon, Jack

2002-07-01

203

Statistical mechanical description of supercritical fluid extraction and retrograde condensation  

NASA Astrophysics Data System (ADS)

The phenomena of supercritical fluid extraction (SFE) and its reverse effect, which is known as retrograde condensation (RC), have found new and important applications in industrial separation of chemical compounds and recovery and processing of natural products and fossil fuels. Full-scale industrial utilization of SFE/RC processes requires knowledge about thermodynamic and transport characteristics of the asymmetric mixtures involved and the development of predictive modeling and correlation techniques for performance of the SFE/RC system under consideration. In this report, through the application of statistical mechanical techniques, the reasons for the lack of accuracy of existing predictive approaches are described and they are improved. It is demonstrated that these techniques also allow us to study the effect of mixed supercritical solvents on the solubility of heavy solutes (solids) at different compositions of the solvents, pressures, and temperatures. Fluid phase equilibrium algorithms based on the conformal solution van der Waals mixing rules and different equations of state are presented for the prediction of solubilities of heavy liquid in supercritical gases. It is shown that the Peng-Robinson equation of state based on conformal solution theory can predict solubilites of heavy liquid in supercritical gases more accurately than the van der Waals and Redlich-Kwong equations of state.

Park, S. J.; Kwak, T. Y.; Mansoori, G. A.

1987-07-01

204

Inhomogeneity of fluid flow in Stirling engine regenerators  

SciTech Connect

The literature relating to inhomogeneity of flow regenerators is briefly reviewed. It is noted that, in contrast to other applications of regenerators, relatively little attention has been paid to the consequences of flow inhomogeneity for thermal regeneration in Stirling cycle machines. The construction of regenerator capsules for a large stationary Stirling engine is described. A test rig is developed to measure the gas velocity profile across the face of the packed regenerator capsules under steady flow conditions. Measured flow profiles for a number of different matrix materials and construction techniques are presented, and it is noted that stacked-mesh regenerator matrices tend to display marked inhomogeneities of flow. The consequences of flow inhomogeneity for flow friction and regenerator effectiveness are analyzed theoretically, and approximate formulae deduced. One method for reducing flow inhomogeneity in stacked-screen matrice

Jones, J.D. (School of Engineering Science, Simon Fraser Univ. Burnaby, British Columbia (CA))

1989-10-01

205

Active And Collaborative Learning Exercises For A First Course In Fluid Mechanics  

NSDL National Science Digital Library

The education literature clearly shows that classroom instruction that requires students to actively participate is superior to the teacher-centered lecture mode of instruction. Moreover, instructional activities that require student interaction and collaboration also promote learning. The superiority of active and collaborative learning to traditional methods applies to any number of measures. To implement active and collaborative learning strategies in a junior-level fluid mechanics class, the authors have developed a number of in-class exercises. These exercises range from activities that consume a large portion of a class period to those that require just a few minutes, or less. Although many instructors may see the benefits of active and collaborative learning strategies, they may be reluctant to use them in their classes because they lack information on how to apply them to specific mechanical engineering subjects. Here we present twenty-three in-class exercises useful for instruction in a first course in fluid mechanics. The attributes of each exercise are delineated. These attributes include the approximate amount of class time required, the degree of collaboration involved (individual effort, pairs, or groups of three or four students), the educational objectives, and the specific subject area(s). Survey results show that our students are highly receptive to these collaborative learning exercises, welcoming them over a traditional lecture format. We also show that these exercises may be adapted readily by others and present limited evidence illustrating their effectiveness in improving student learning.

Zappe, Sarah; Pauley, Laura; Turns, Stephen

2009-10-14

206

Novel Lagrangian formulation for self-consistent fluid mechanics problems  

SciTech Connect

A novel Lagrangian formulation is proposed for self-consistent fluid mechanics problems, like magnetohydrodynamics, in which the force field is to be determined along with the velocity field. A key feature of the formulation is that the momentum balance and continuity equations are exactly satisfied locally, even in numerical applications. This is accomplished by choosing a Lagrangian representation for the velocity field and using the momentum balance equation to cmpute the force field pointwise in terms of the Lagrangian mapping function. The formulation is illustrated for one-dimensional electrohydrodynamics, in which case the mass continuity and momentum balance equations are coupled to the Poisson equation. The formulation may be suitable for describing phenomena like the formation of convective cells, boundary layers, or discontinuities in a natural way.

Lewis, H.R.

1985-01-01

207

Fluid mechanics constraints on LIPs origin and formation  

NASA Astrophysics Data System (ADS)

Large Igneous Provinces represent the most voluminous igneous events on our planets and have probably ponctuated the Earth history since at least 3 Gyr. Recent fluid mechanics experiments on thermal convection show that the existence and characteristics of LIPs put tight constraints on mantle dynamics, structure and evolution. In particular, a relatively quick emplacement, hot temperature and large volume of LIPs would require a origin of LIPs deep in the lower mantle, a mantle rheology which depends strongly on temperature, and the presence of chemical heterogeneities. In the latter case, the laboratory experiments further suggest that LIPs could be heterogeneous in composition, could be followed by a variety of volcanic activities, and could even trigger subduction.

Davaille, A.

2008-12-01

208

Hydro-mechanical overhead for internal combustion engine  

SciTech Connect

This patent describes a hydro-mechanical overhead for a multi-cylinder four-cycle internal combustion engine having a camshaft, intake valve pushtube means driven by the camshaft, exhaust valve pushtube means driven by the camshaft, at least one intake and exhaust valve for each cylinder of the multi-cylinder internal combustion engines and a piston for each cylinder of the engine. The process comprises an intake valve master piston means for each engine cylinder. Each intake valve master piston means is driven by one of the intake valve pushtube means. There is an exhaust valve master piston means for each engine cylinder, and each exhaust valve master piston means is driven by one of the exhaust valve pushtube means.

Meistrick, Z.S.; Price, R.B.

1987-05-12

209

Applications of the discrete element method in mechanical engineering  

Microsoft Academic Search

Compared to other fields of engineering, in mechanical engineering, the Discrete Element Method (DEM) is not yet a well known\\u000a method. Nevertheless, there is a variety of simulation problems where the method has obvious advantages due to its meshless\\u000a nature. For problems where several free bodies can collide and break after having been largely deformed, the DEM is the method

Florian Fleissner; Timo Gaugele; Peter Eberhard

2007-01-01

210

Some Pure and Applied Fluid Mechanics Research in France.  

National Technical Information Service (NTIS)

This report describes the activities of two research establishments in France: The Laboratoire de Mecanique des Fluides of the Ecole Centrale de Lyon and Techniques des Fluides, Grenoble. Visiting the two facilities on the same trip allowed good compariso...

R. E. A. Arndt

1975-01-01

211

Controlling health risks from workplace exposure to metalworking fluids in the United Kingdom engineering industry.  

PubMed

On October 15, 2002, the United Kingdom (UK) Health and Safety Executive (HSE) launched new guidance for the engineering industry, aimed at reducing health risks from metalworking fluids (MWFs). This guidance was the culmination of many years of work on this subject. In the early 1990s, the UK occupational exposure standards (OES) for oil mist were 5 mg/m(-3) 8-hour time-weighted average (TWA), and 10 mg/m(-3) short-term exposure limit (STEL). This was only applicable to highly refined mineral oil mists and there was no exposure limit for water-mix MWFs (emulsions, semi-synthetics, and synthetics). HSE therefore undertook to review the existing exposure limit for neat mineral oil mists (neat oils are fluids that contain highly refined mineral oils and additives, and are used neat without mixing with water) and consider developing one for water-mix MWFs. This led to the development of new air-sampling methods, a comprehensive survey, and the development of new good practice guidance in the place of statutory exposure limits. This new good practice guidance has been endorsed and launched with the help of relevant industry supplier, employer, and employee associations. The guidance builds on the philosophy of tackling health risks as a holistic approach; for example, not just tackling mist control through the use of ventilation, but also fluid selection, fluid delivery, and fluid management (fluid management means to effectively manage all aspects of the fluid, from storage and stock preparation to sump cleaning and fluid disposal, etc.). Tools, such as laminated task sheets, are provided to make it user friendly. It also demonstrates the business benefits from this approach, that managing your MWFs effectively can reduce the incidence of ill health, reduce fluid and disposal costs, increase tool life, and improve machining performance. PMID:14555440

Stear, Martin A

2003-11-01

212

Student Projects: Hands-on Experience with Mechanical Engineering Technology  

NSDL National Science Digital Library

For several years, the Engineering Technology Department (ETD) at Middle Tennessee State University (MTSU) has sponsored a variety of student led competition vehicle programs. These programs have enjoyed considerable success in competitions around the country, and have spawned a thriving research community at MTSU, culminating with the foundation of the Experimental Vehicles Program (EVP) at MTSU during the summer of 2004. The vehicle projects sponsored by EVP, including a Solar Vehicle, Solar Boat, Formula car, Mini Baja, and a human powered Moon Buggy, give engineering technology students invaluable experience solving real world engineering problems. The vehicle teams themselves provide a support network that introduces younger students to more experienced older students who are glad to share the hard won knowledge they have gained, and are often willing to help with homework. This paper illustrates the effectiveness of extra-curricular student led projects in educating students for the challenges they will face on the job. EVP, along with other ETD sponsored projects, supplement the standard Mechanical Engineering Technology curriculum at MTSU by: " Attracting new and undeclared students to the Engineering Technology Department and the Mechanical Engineering Technology (MET) concentration " Increasing retention rates among first year MET students " Challenging those students to apply their classroom skills in designing and building vehicles for national and international competitions " Encouraging independent research into specific problems associated with vehicle design and construction " Fostering effective communication, leadership, and project management skills.

Foroudastan, Saeed; Campbell, Ian D.

2011-07-04

213

Introducing Non-Newtonian Fluid Mechanics Computations with Mathematica in the Undergraduate Curriculum  

ERIC Educational Resources Information Center

|We study four non-Newtonian fluid mechanics problems using Mathematica[R]. Constitutive equations describing the behavior of power-law, Bingham and Carreau models are recalled. The velocity profile is obtained for the horizontal flow of power-law fluids in pipes and annuli. For the vertical laminar film flow of a Bingham fluid we determine the…

Binous, Housam

2007-01-01

214

Variational Principles of Fluid Mechanics and Electromagnetism: Imposition and Neglect of the Lin Constraint  

Microsoft Academic Search

Variational principles in classical fluid mechanics and electromagnetism have sprinkled the literature since the eighteenth century. Even so, no adequate variational principle in the Eulerian description of matter was had until 1968 when an Eulerian variational principle was introduced which reproduces Euler's equation of fluid dynamics. Although it successfully produces the appropriate equation of motion for a perfect fluid, the

Ross Roundy Allen Jr.; R. R. Jr

1987-01-01

215

Segmenting Crossing Fiber Geometries Using Fluid Mechanics Tensor Distribution Function Tractography  

Microsoft Academic Search

We introduce a fluid mechanics based tractography method that estimates the most likely connection path between points in a tensor distribution function (TDF) dataset. We simulated the flow of an artificial fluid whose properties are related to the underlying TDF dataset. The resulting fluid velocity was used as a metric of connection strength. We validated our algorithm using a digital

Nathan S. Hageman; Alex D. Leow; David W. Shattuck; Liang Zhan; Paul M. Thompson; Siwei Zhu; Arthur W. Toga

2009-01-01

216

Fundamental Studies of Fluid Mechanics: Stability in Porous Media  

SciTech Connect

This work has been concerned with theoretical, computational and experimental studies of a variety of flow and transport problems that are of generic interest and applicability in energy-related and energy-intensive processes. These include the following. (1) Problems associated with oil recovery: the global economy continues to be dependent on the stable and predictable supply of oil and fossil fuels. This will remain the case for the near term, as current estimates are that world production of oil will peak between 2025 and 2100, depending on assumptions regarding growth. Most of these resources reside in porous rocks and other naturally occurring media. Studies of flow-induced instabilities are relevant to the areas of secondary and enhanced oil recovery. (2) Small scale and Stokes flows: flows in microgeometries and involving interfaces and surfactants are of interest in a myriad of energy-related contexts. These include: pore-level modeling of the fundamental processes by which oil held in porous materials is mobilized and produced; heating and cooling energy cycles involving significant expenditure of energy in conditioning of human environments, heat pipes, and compact heat exchangers; and energy efficiency in large scale separation processes such as distillation and absorption-processes that underlie the chemical process industries. (3) Coating flows: these are of interest in information technologies, including the manufacture of integrated circuits and data storage and retrieval devices. It is estimated that 50-70% of the starting raw materials and intermediate devices in information technology processes must be discarded as a result of imperfections and failure to meet specifications. These in turn are often the result of the inability to control fluid-mechanical processes and flow instabilities. Our work over the grant period is primarily fundamental in nature. We are interested in establishing general principles and behaviors that relate to a variety of processes in a variety of contexts. Our work has focused and will continue to focus on fluid mechanical phenomena that are of interest in energy-related technologies, with an emphasis on interfacial flows.

George M. Homsy

2005-04-28

217

Mechanisms of fluid production in smooth adhesive pads of insects  

PubMed Central

Insect adhesion is mediated by thin fluid films secreted into the contact zone. As the amount of fluid affects adhesive forces, a control of secretion appears probable. Here, we quantify for the first time the rate of fluid secretion in adhesive pads of cockroaches and stick insects. The volume of footprints deposited during consecutive press-downs decreased exponentially and approached a non-zero steady state, demonstrating the presence of a storage volume. We estimated its size and the influx rate into it from a simple compartmental model. Influx was independent of step frequency. Fluid-depleted pads recovered maximal footprint volumes within 15 min. Pads in stationary contact accumulated fluid along the perimeter of the contact zone. The initial fluid build-up slowed down, suggesting that flow is driven by negative Laplace pressure. Freely climbing stick insects left hardly any traceable footprints, suggesting that they save secretion by minimizing contact area or by recovering fluid during detachment. However, even the highest fluid production rates observed incur only small biosynthesis costs, representing less than 1 per cent of the resting metabolic rate. Our results show that fluid secretion in insect wet adhesive systems relies on simple physical principles, allowing for passive control of fluid volume within the contact zone.

Dirks, Jan-Henning; Federle, Walter

2011-01-01

218

An engineering model for adsorption of gases onto flat surfaces and clustering in supercritical fluids  

SciTech Connect

Physical adsorption is used in gas purification processes such as the removal of volatile organic compounds from stack gases, as a means of fractionating fluids that are difficult to separate by other methods, and in adsorbent regenerations using supercritical fluids. Physical adsorption is also of interest in transportation and storage of radioactive gases, in separation and purification of lower hydrocarbons, in supercritical extractions and chromatography, and in critical point drying. The authors present an engineering model to describe physical adsorption from sub- to supercritical conditions on flat walls and clustering in supercritical fluids using a single temperature-independent parameter for fluid-solid interactions. The fluid-solid potential is superimposed on the Peng-Robinson equation of state, and the configurational energy integral in the inhomogeneous fluid phase is simplified with a local density approximation. This model is capable of quantitative fits over wide pressure and temperature ranges. Model predictions for physical adsorption of pure gases on flat walls are compared with experimental surface excess data, and model predictions for describing the clustering phenomenon are compared with experimental fluorescence spectra.

Subramanian, R.; Pyada, H.; Lira, C.T. [Michigan State Univ., East Lansing, MI (United States). Dept. of Chemical Engineering

1995-11-01

219

Statistical mechanics of homogeneous partly pinned fluid systems.  

PubMed

The homogeneous partly pinned fluid systems are simple models of a fluid confined in a disordered porous matrix obtained by arresting randomly chosen particles in a one-component bulk fluid or one of the two components of a binary mixture. In this paper, their configurational properties are investigated. It is shown that a peculiar complementarity exists between the mobile and immobile phases, which originates from the fact that the solid is prepared in presence of and in equilibrium with the adsorbed fluid. Simple identities follow, which connect different types of configurational averages, either relative to the fluid-matrix system or to the bulk fluid from which it is prepared. Crucial simplifications result for the computation of important structural quantities, both in computer simulations and in theoretical approaches. Finally, possible applications of the model in the field of dynamics in confinement or in strongly asymmetric mixtures are suggested. PMID:21230672

Krakoviack, Vincent

2010-12-02

220

Thermoplastics as engineering materials: The mechanics, materials, design, processing link  

Microsoft Academic Search

While the use of plastics has been growing at a significant pace because of weight reduction, ease of fabrication of complex shapes, and cost reduction resulting from function integration, the engineering applications of plastics have only become important in the past fifteen years. An inadequate understanding of the mechanics issues underlying the close coupling among the design, the processing (fabrication),

Vijay K. Stokes

1995-01-01

221

Evaluating Risk Awareness in Undergraduate Students Studying Mechanical Engineering  

ERIC Educational Resources Information Center

|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…

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

2010-01-01

222

MECHANICAL ENGINEERING ACTIVITIES IN THE SUSPENSION REACTOR PROJECT  

Microsoft Academic Search

In the preceding articles of this series the KEMA project for the ; development of a suspension reactor was explained in general terms. In this ; article, mechanical engineering aspects were discussed in greater detail. A ; review was given of the preliminary investigations for the design, construction, ; and operation of the KSTR (KEMA Suspension Test Reactor). (tr-auth);

1963-01-01

223

Development of mechanical engineering curricula at the University of Minho  

Microsoft Academic Search

The implementation of the Bologna protocol in the European Union has set new goals for the whole higher education system as: (a) a quality assessment for university courses; (b) a framework for the exchange of students and academics; and (c) an opportunity for changing the teaching\\/learning procedures and methodologies. Within the context, the mechanical engineering curricula at the University of

J. C. Fernandes Teixeira; J. Ferreira Da Silva; P. Flores

2007-01-01

224

Feature-based reverse engineering of mechanical parts  

Microsoft Academic Search

Reverse engineering of mechanical parts requires extraction of information about an instance of a particular part sufficient to replicate the part using appropriate manufacturing techniques. This is important in a wide variety of situations, since functional CAD models are often unavailable or unusable for parts which must be duplicated or modified. Computer vision techniques applied to three-dimensional (3-D) data acquired

William B. Thompson; Jonathan C. Owen; H. J. de St. Germain; Stevan R. Stark; Thomas C. Henderson

1999-01-01

225

Feature-Based Reverse Engineering of Mechanical Parts  

Microsoft Academic Search

Reverse engineering of mechanical parts requires extraction of information about an instance of a particular part sufficient to replicate the part using appropriate manufacturing techniques. This is important in a wide variety of situations, since functional CAD models are often unavailable or unusable for parts which must be duplicated or modified. Computer vision techniques applied to 3-D data acquired using

William B. Thompson; Jonathan C. Owen; H. James

1995-01-01

226

Computational estimation of fluid mechanical benefits from a fluid deflector at the distal end of artificial vascular grafts.  

PubMed

Intimal hyperplasia at the distal anastomosis is considered to be an important determinant for arterial and arteriovenous graft failure. The connection between unhealthy hemodynamics and intimal hyperplasia motivates the use of computational fluid dynamics modeling to search for improved graft design. However, studies on the fluid mechanical impact on intimal hyperplasia at the suture line intrusion have previously been scanty. In the present work, we focus on intimal hyperplasia at the suture line and illustrate potential benefits from the introduction of a fluid deflector to shield the suture line from unhealthily high wall shear stress. PMID:23260571

Roos, M W; Wadbro, E; Berggren, M

2012-12-20

227

Fluid mechanics of method of separating motile cells  

NSDL National Science Digital Library

If the Reynolds number is small enough (Re<<1), then two fluids can flow in parallel in direct contact, exchanging momentum and species only by diffusion. If the interface is stable, then this system can be used as a filter. In this problem, the flow fields in both fluids are found. The system here has a diffusing species which is motile cells with a random behavior relative to the flowing fluid.

Krane, Matthew J.; Martinez, Carlos

2008-10-25

228

Microscopic Mechanisms of the Brittleness of Viscoelastic Fluids  

NASA Astrophysics Data System (ADS)

We show that a large class of viscoelastic fluids, i.e., transient networks, are brittle according to the Griffith’s theory of solid fracture. However, contrary to solids, cracks are intrinsic to the material arising from the equilibrium nature of the fluid microstructure. The brittleness of these fluids comes from thermal fluctuations of bonds distribution. In this approach, the rupture stress is predicted to be on the order of the Young modulus, in very good agreement with experimental values.

Tabuteau, H.; Mora, S.; Porte, G.; Abkarian, M.; Ligoure, C.

2009-04-01

229

Immunosensor with fluid control mechanism for salivary cortisol analysis.  

PubMed

The purpose of this research is to demonstrate a new design for a cortisol immunosensor for the noninvasive and quantitative analysis of salivary cortisol. We propose a cortisol immunosensor with a fluid control mechanism which has both a vertical flow and a lateral flow. The detected current resulting from a competitive reaction between the sample cortisol and a glucose oxidase (GOD)-labeled cortisol conjugate was found to be inversely related to the concentration of cortisol in the sample solution. A calibration curve using the relative detected current showed a R(2)=0.98 and CV=14% for a range of standard cortisol solutions corresponding to the concentrations of native salivary cortisol (0.1-10 ng/ml). The measurement could be accomplished within 35 min and the cortisol immunosensor could be reused. These results show promise for realizing an on-site and easy-to-use biosensor for cortisol. Used for evaluation of human salivary cortisol levels, the cortisol immunosensor measurement corresponded closely with commercially available ELISA method (R(2)=0.92). Our results indicate the promise of the new cortisol immunosensor for noninvasive, point of care measurement of human salivary cortisol levels. PMID:22939507

Yamaguchi, Masaki; Matsuda, Yohei; Sasaki, Shohei; Sasaki, Makoto; Kadoma, Yoshihiro; Imai, Yoshikatsu; Niwa, Daisuke; Shetty, Vivek

2012-08-16

230

Dynamics of fluid and light intensity in mechanically stirred photobioreactor.  

PubMed

Turbulent flows in a single-stage and a two-stage impeller-stirred photobioreactor with a simple geometric configuration were analyzed using computational fluid dynamics. The trajectories of the microorganisms entrained in the flow field were traced by the particle tracking method. By projecting these trajectories onto a radial-axial (r-z) plane with a given azimuth angle, we were able to observe four different dynamics zones: circulation, pure rotation, trap, and slow-motion. Within the pure rotation zone, turbulence can be observed near the edges of the impeller. The light intensity and the light/dark cycles subjected by the microorganisms differ significantly in these zones. These differences can be further changed by providing different incident light illuminations on the reactor surface. The dynamics zones can be altered by modifying the geometric configuration of the reactor and the impeller stirring mechanism. In combination with the utilization of different incident light illuminations, the light intensity dynamics and the light/dark cycles subjected by the microorganisms can be controlled such that an optimal photobioreactor design with a high efficiency of light utilization and a high formation rate of the biochemical products can be realized. PMID:23892110

Zhang, T

2013-07-24

231

The role of neural networks in fluid mechanics and heat transfer  

Microsoft Academic Search

The recent applications of Artificial Neural Networks (ANNs) to fluid mechanics and heat transfer are presented. ANNs have proved beneficial by their capability in modelling complex nonlinear problems as well as providing a fast, automatic method in some applications. In heat transfer the backpropagation model has been predominant and it has also been widely used in fluid mechanics. However, flow

S. Ashforth-Frost; V. N. Fontama; K. Jambunathan; S. L. Hartle

1995-01-01

232

Teaching Fluid Mechanics to the Beginning Graduate Student--An Objective-Oriented Approach.  

ERIC Educational Resources Information Center

A premature embarkation in specialized areas of fluid mechanics by the beginning graduate student, without having first thoroughly learned the basics, leads to learning difficulties and destroys zeal for learning. To avoid these problems, many schools in the U.S. offer beginning graduate courses in fluid mechanics (BGCFM). Because the success or…

Liu, Henry

233

Fluid Flow Analysis of the SSME (Space Shuttle Main Engine) High Pressure Fuel and Oxidizer Turbine Coolant Systems.  

National Technical Information Service (NTIS)

The objective is to provide improved analysis capability for the Space Shuttle Main Engine (SSME) high pressure fuel and oxidizer turbine coolant systems. Each of the systems was analyzed to determine fluid flow rate and thermodynamic and transport proper...

G. A. Teal

1989-01-01

234

Mechanical properties of magnetorheological fluids under squeeze-shear mode  

NASA Astrophysics Data System (ADS)

Magnetorheological (MR) fluids is very promising intelligent materials and it can rapidly by changed from a liquid state to a solid state in a magnetic field. Various industries are full of potential MR fluids applications, but current MR fluids have the limitation that their yield stresses are not strong enough to meet some industrial requirements. The crucial problem is how to enhance the yield stress of MR fluids. Electrorheological (ER) fluids, similar to MR fluids, can be achieved high strength under squeeze mode, which proposed a method to achieve high-efficiency MR fluids by study of shear after compression. The performance of MR fluids under squeeze-shear mode was inveatigated. Magnetic fields being generated by two coils carrying different magnitudes of DC electrical current were applied on the MR fluids when shearing after compression were carried out on a self-constructed test system. For each trail the current in the coil and the compressive force were kept constant and the instantaneous yield stress was recorded. The relations of compression stress versus compression strain, yield stress versus compression stress were studied under different applied currents. The ploting of compressive stress against compressive strain has been observed to have three regions: the first and third regions has a linear relationship and the second region has a zero increasing. The slope of the curve was found to be larger when the applied current was larger. The SG MRF2035 without compression process has a yield stress about 53kPa at most even if increasing the applied current. But after compression, the yield stress increase with the increasing compressive stress under the different applied currents. And some promising results are obtained, for example, when the applied current is 2.5A and the compressive stress is 2.0MPa, the yield stress exceeds 1100kPa. It showed that the yield stress of MR fluids after compression was much stronger than that of uncompressed MR fluids under the same applied current. The enhanced yield stress of MR fluids can be utilized to design the MR clutch and brake for new structure and will make MR fluids technology attractive for many applications.

Wang, Hong-yun; Zheng, Hui-qiang; Li, Yong-xian; Lu, Shuang

2008-12-01

235

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

NASA Astrophysics Data System (ADS)

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 thanks to the expert reviewers who have spared their time reviewing the papers. We also highly appreciate the assistance offered by many volunteers in the preparation of the conference proceedings. All papers in ICMER 2011 have the opportunity to be published in IOP Conference Series: Materials Science and Engineering, (indexed by Scopus, Ei Compendex, Inspec), International Journal of Automotive and Mechanical Engineering (IJAME) and Journal of Mechanical Engineering and Sciences (JMES). Professor Dr Hj Rosli Abu Bakar Chairman ICMER 2011

Abu Bakar, Rosli

2012-09-01

236

Crustal-scale fluid transport: Magnitude and mechanisms  

NASA Astrophysics Data System (ADS)

Fluids in the crust of the Earth play an important role in the geochemical and geophysical structure of the crust. They are responsible for a multitude of chemical/rock reactions and couple directly with geophysical processes and the geophysical imaging of the crust. The known depth of significant fluid reaction/transport has been increasing in recent years with the detailed study of drilled and exhumed solid phase samples. From both isotopic and chemical evidence, it is clear that meteoric fluids can penetrate at least 10 kilometers into the crust of the Earth (fluids have also been sampled directly from a depth of 12 km in the Kola Peninsula Drillhole) and the horizontal scale of fluid transport is now known to extend 100's of kilometers. Furthermore, as the kinetics and reaction dynamics (rather than simple equilibrium)are included to explain these observations, estimates of the fluid volumes (expressed as a water/rock ratio)required to emplace these fluid derived rock suites and deposits have increased steadily.

Torgersen, Thomas

237

Take-Home Experiments in Undergraduate Fluid Mechanics Education  

NASA Astrophysics Data System (ADS)

Hands-on take-home experiments, assigned as homework, are useful as supplements to traditional in-class demonstrations and laboratories. Students borrow the equipment from the department's equipment room, and perform the experiment either at home or in the student lounge or student shop work area. Advantages include: (1) easy implementation, especially for large classes, (2) low cost and easy duplication of multiple units, (3) no loss of lecture time since the take-home experiment is self-contained with all necessary instructions, and (4) negligible increase in student or teaching assistant work load since the experiment is assigned as a homework problem in place of a traditional pen and paper problem. As an example, a pump flow take-home experiment was developed, implemented, and assessed in our introductory junior-level fluid mechanics course at Penn State. The experimental apparatus consists of a bucket, tape measure, submersible aquarium pump, tubing, measuring cup, and extension cord. We put together twenty sets at a total cost of less than 20 dollars per set. Students connect the tube to the pump outlet, submerge the pump in water, and measure the volume flow rate produced at various outflow elevations. They record and plot volume flow rate as a function of outlet elevation, and compare with predictions based on the manufacturer's pump performance curve (head versus volume flow rate) and flow losses. The homework assignment includes an online pre-test and post-test to assess the change in students' understanding of the principles of pump performance. The results of the assessment support a significant learning gain following the completion of the take-home experiment.

Cimbala, John

2007-11-01

238

Mechanics of undulatory swimming in a frictional fluid.  

PubMed

The sandfish lizard (Scincus scincus) swims within granular media (sand) using axial body undulations to propel itself without the use of limbs. In previous work we predicted average swimming speed by developing a numerical simulation that incorporated experimentally measured biological kinematics into a multibody sandfish model. The model was coupled to an experimentally validated soft sphere discrete element method simulation of the granular medium. In this paper, we use the simulation to study the detailed mechanics of undulatory swimming in a "granular frictional fluid" and compare the predictions to our previously developed resistive force theory (RFT) which models sand-swimming using empirically determined granular drag laws. The simulation reveals that the forward speed of the center of mass (CoM) oscillates about its average speed in antiphase with head drag. The coupling between overall body motion and body deformation results in a non-trivial pattern in the magnitude of lateral displacement of the segments along the body. The actuator torque and segment power are maximal near the center of the body and decrease to zero toward the head and the tail. Approximately 30% of the net swimming power is dissipated in head drag. The power consumption is proportional to the frequency in the biologically relevant range, which confirms that frictional forces dominate during sand-swimming by the sandfish. Comparison of the segmental forces measured in simulation with the force on a laterally oscillating rod reveals that a granular hysteresis effect causes the overestimation of the body thrust forces in the RFT. Our models provide detailed testable predictions for biological locomotion in a granular environment. PMID:23300407

Ding, Yang; Sharpe, Sarah S; Masse, Andrew; Goldman, Daniel I

2012-12-27

239

Digital three-color holographic interferometry devoted to fluid mechanics  

NASA Astrophysics Data System (ADS)

This paper presents work and results performed with LAUM collaboration in digital three-color holographic interferometry applied to Fluid Mechanics. In this method, three different wavelengths are used as luminous light source of the interferometer and the optical setup generates three micro interferences fringes which constitute three spatial carrier frequencies. When these images are recorded with a color sensor, the resolution of reconstructed hologram depends on the pixel size and pixel number of the sensor used for recording and also, the shape and the overlapping of three filters of color sensor influence strongly the three reconstructed images. This problem can be directly visualized in 2D Fourier planes on red, green and blue channels. To better understand this problem and to avoid parasitic images generated at the reconstruction, three different sensors have been tested : a CCD sensor equipped with a Bayer filter, a Foveon sensor and a 3CCD sensor. The best results have been obtained with the last one. In the recording principle, interference micro fringes produced by the superimposition of three reference waves and three measurement waves can be simultaneously recorded on the three spectral bands (red, green, and blue). Phase and amplitude images are computed using 2D Fourier transform in delayed time. Spectral filtering is applied on each Fourier plane in order to eliminate the parasitic diffraction orders. Then, phase differences are obtained by subtracting the reference phase to the probe phase. Several optical setups were tested and the best configuration allows the visualization of field about 70mm and increases the sensitivity since the measurement wave crosses twice the test section. Interferences induced by the wake flow have been recorded and intensities have been computed from the phase differences. Finally, one shows that fringes obtained with this process are those found with real-time color holographic interferometry using classical holographic plates.

Desse, J. M.; Picart, P.; Tankam, P.

2010-09-01

240

Analysis of Premixed Charge Compression Ignition Combustion with a Sequential Fluid Mechanics-Multizone Chemical Kinetics Model  

SciTech Connect

We have developed a methodology for analysis of PCCI engines that applies to conditions in which there is some stratification in the air-fuel distribution inside the cylinder at the time of combustion. Our analysis methodology consists of two stages: first, a fluid mechanics code is used to determine temperature and equivalence ratio distributions as a function of crank angle, assuming motored conditions. The distribution information is then used for grouping the mass in the cylinder into a two-dimensional (temperature-equivalence ratio) array of zones. The zone information is then handed on to a detailed chemical kinetics model that calculates combustion, emissions and engine efficiency information. The methodology applies to situations where chemistry and fluid mechanics are weakly linked. The results of the multi-zone model have been compared to the results obtained from a fully integrated code, in which a chemical kinetics code is directly linked into a fluid mechanics code to calculate chemistry in every cell of the grid. The results show that the multi-zone model predicts burn duration and peak cylinder pressure with good accuracy. However, ignition timing predicted by the multi-zone model is sensitive to the transition angle between the fluid mechanics code and the chemical kinetics code. The paper explores the possibility of using three different criteria for determining the transition angle: fraction of heat release at the time of ignition, temperature of the hottest cell at the time of ignition, and a fixed crank angle of transition. The results show that the three criteria have some validity as transition criteria. Further research is necessary to investigate the effect of fuel properties and operating conditions on transition angle.

Aceves, S M; Flowers, D L; Espinosa-Loza, F; Babajimopoulos, A; Assanis, D N

2004-09-30

241

Lets Rock the Boat: Evaluating the Concept of Stability in Fluid Mechanics  

NSDL National Science Digital Library

As an upper level civil engineering course, Fluid Mechanics, often presents concepts that are unfamiliar to engineering students, at least to the level of understanding expected in the course. Many of these fundamentals concepts are critical to success in the course, but are frequently difficult to visualize simply with figures and equations. Additionally, many laboratory exercises for students involve a cookbook type approach which increases the chance of the attainment of reliable results, but inhibits curiosity and decreases the development of an independent engineering formation of ideas associated with problem solving. A possible solution to both issues is the incorporation of in class activities which illustrate fundamental concepts, engage students in an active learning environment, and allow for the students themselves to create a testing program. The complication lies in determining a suitable topic and in creating an activity broad enough to allow for creative testing development but narrow enough to insure at least a marginal level of reliable results. The topic chosen by the authors was that of stability, one of the basic fundamental concepts in fluid mechanics. Working in groups of four to five students, the class was asked to develop an independent testing program that addressed the qualitative effects of adjusting weight in any one, or a combination of multiple, different directions (i.e. adjustments in the x, y, and / or z plane) on a floating object. Students were given supplies to create a model barge: a Styrofoam brick, cardboard sticks, modeling clay and containers sufficiently large to allow for floatation and movement when the barge was placed inside. No restrictions were placed on the direction in which the brick was to be placed in the water, the number and location of masts, or the number, magnitude and location of weight(s). Students were told the activity was to be summarized in a one-page paper, including testing procedure, results, and conclusions and were allowed thirty minutes for experimental setup, testing, and clean-up. Determination of student comprehension was assessed through both the summary paper, as well as an exam question. Results showed a high level of understanding, both in the short term, as concluded with the paper outcomes, as well as long term retention, validated with testing results. Quantitative analysis can easily be incorporated into the program by providing measuring instruments (rulers, calipers, and a balance) if a more robust study is desired.

Kunberger, Tanya; Bondehagen, Diane

2009-09-29

242

Development of Hands-On Student Experience with Modern Facilities, Measurement Systems, and Uncertainty Analysis in Undergraduate Fluids Engineering Laboratories  

Microsoft Academic Search

Development described of hands-on student experience with modern facilities, measurement systems, and uncertainty analysis in undergraduate fluids engineering laboratories. Classroom and pre-lab lectures and laboratories teach students experimental fluid dynamics (EFD) methodology and uncertainty analysis (UA) procedures following a step-by-step approach, which mirrors the \\

Fred Stern; Marian Muste; Surageet Ghosh; Jun Shao; Don Yarbrough

243

Adaptive Local Grid Refinement in Computational Fluid Mechanics.  

National Technical Information Service (NTIS)

Several promising new techniques for efficient and accurate numerical solution of large-scale fluid flow problems have been developed. These methods include self-adaptive mesh modification techniques for applications requiring front-tracking and local gri...

R. E. Ewing M. B. Allen M. J. Djomehri J. H. George E. L. Isaacson

1987-01-01

244

Fluid Transport Mechanisms in Breast Gross Cystic Disease.  

National Technical Information Service (NTIS)

The goal of this research is to develop a pharmacological strategy for reducing or eliminating the pathological accumulation of fluid that occurs in breast gross cystic disease (GCD). We have begun an analysis of the transport proteins and intracellular s...

S. Miller

1997-01-01

245

Teaching Computer-Aided Design of Fluid Flow and Heat Transfer Engineering Equipment.  

ERIC Educational Resources Information Center

|Describes a teaching program for fluid mechanics and heat transfer which contains both computer aided learning (CAL) and computer aided design (CAD) components and argues that the understanding of the physical and numerical modeling taught in the CAL course is essential to the proper implementation of CAD. (Author/CMV)|

Gosman, A. D.; And Others

1979-01-01

246

Fundamental studies of fluid mechanics and stability in porous media  

SciTech Connect

We have been active in four areas: Numerical and analytical studies of viscous fingering in miscible displacements, including non- monotonic mobility profiles; numerical and analytical studies of the effect of non-Newtonian fluid characteristics on instabilities; experimental studies of instabilities of moving contact lines for Newtonian and non-Newtonian fluids; and studies of natural convective energy transport due to time-dependent body forces.

Homsy, G.M.

1992-07-01

247

A biocompatible tissue scaffold produced by supercritical fluid processing for cartilage tissue engineering.  

PubMed

Supercritical fluids are used in various industrial fields, such as the food and medical industries, because they have beneficial physical and chemical properties and are also nonflammable and inexpensive. In particular, supercritical carbon dioxide (ScCO(2)) is attractive due to its mild critical temperature, pressure values, and nontoxicity. Poly(L-lactide-co-?-caprolactone) (PLCL), which is a biocompatible, biodegradable, and very elastic polymer, has been used in cartilage tissue engineering. However, organic solvents, such as chloroform or dichloromethane, are usually used for the fabrication of a PLCL scaffold through conventional methods. This leads to a cytotoxic effect and long processing time for removing solvents. To alleviate these problems, supercritical fluid processing is introduced here. In this study, we fabricated a mechano-active PLCL scaffold by supercritical fluid processing for cartilage tissue engineering, and we compared it with a scaffold made by a conventional solvent-casting method in terms of physical and biological performance. Also, to examine the optimum condition for preparing scaffolds with ScCO(2), we investigated the effects of pressure, temperature, and the depressurization rate on PLCL foaming. The PLCL scaffolds produced by supercritical fluid processing had a homogeneously interconnected porous structure, and they exhibited a narrow pore size distribution. Also, there was no cytotoxicity of the scaffolds made with ScCO(2) compared to the scaffolds made by the solvent-pressing method. The scaffolds were seeded with chondrocytes, and they were subcutaneously implanted into nude mice for up to 4 weeks. In vivo accumulation of extracellular matrix of cell-scaffold constructs demonstrated that the PLCL scaffold made with ScCO(2) formed a mature and well-developed cartilaginous tissue compared to the PLCL scaffold formed by solvent pressing. Consequently, these results indicated that the PLCL scaffolds made by supercritical fluid processing offer well-interconnected and nontoxic substrates for cell growth, avoiding problems associated with a solvent residue. This suggests that these elastic PLCL scaffolds formed by supercritical fluid processing could be used for cartilage tissue engineering. PMID:22834918

Kim, Su Hee; Jung, Youngmee; Kim, Soo Hyun

2012-09-07

248

Encyclopedia of fluid mechanics. Volume 2 - Dynamics of single-fluid flows and mixing  

Microsoft Academic Search

Various papers on the dynamics of single-fluid flows and mixing are presented. The general topics addressed include: channel and free surface flows, mixing phenomena and practices, and fluid transport equipment. Individual papers discuss: statistics of deep water surface waves, unstable turbulent channel flow, hydraulic jumps and internal flows, wave attenuation in open channel flow, straight sediment stable channels, three-dimensional deep-water

N. P. Cheremisinoff

1986-01-01

249

CCMR: Comparing Mechanical Consequences of Cell Type in Engineered Cartilage  

NSDL National Science Digital Library

The goal of engineering cartilage is to produce cartilage that has the same form and function as native cartilage.Using a standard uniaxial confined compression, the aggregate modulus of alginate seeded with chondrocytes, mesenchymal stem cells and fibrochondrocytes were compared. This study suggests that cell type plays a role in the construct aggregate mechanical properties, and that the chondrocytes and fibrochondrocytes enhance the aggregate modulus more than MSCs.

Cox, Marie

2004-08-17

250

An analytical model of heat transfer and fluid dynamic performances of an unconventional NTR engine for manned interplanetary missions  

Microsoft Academic Search

An analytical model of fluid flow and heat transfer of a Nuclear Thermal Rocket (NTR) engine concept is presented. The engine is based on the direct conversion of the kinetic energy of the fission fragments (FFs) into the propellant enthalpy. The FFs can escape from an extremely thin layer of fissionable material: a sufficiently large surface coated with few micrometers

Ivan Di Piazza

2009-01-01

251

Numerical simulation and optimization on heat transfer and fluid flow in cooling channel of liquid rocket engine thrust chamber  

Microsoft Academic Search

Purpose – To find the optimal number of channels of rocket engine thrust chamber, it was found that the optimal channel number is 335, at which the cooling effect of the thrust chamber cooling channel reaches the best, which can be helpful to design rocket engine thrust chamber. Design\\/methodology\\/approach – The commercial computational fluid dynamics (CFD) software FLUENT with standard

Qiuwang Wang; Feng Wu; Min Zeng; Laiqin Luo; Jiguo Sun

2006-01-01

252

Cowboy Fluid Mechanics: Lariat Modes of a Viscous Rope  

NASA Astrophysics Data System (ADS)

A thin filament of viscous fluid falling onto a surface winds itself into a helical coil whose angular frequency of rotation ? depends on the fall height H, the flow rate, and the fluid properties. We have studied a novel variant of this phenomenon in which the nozzle ejecting the fluid rotates about a vertical axis at a constant rate ?. In laboratory experiments using viscous corn syrup, we observe that the filament coils in the normal way when ??. However, when ? ? and H is sufficiently large, a new ``lariat'' mode appears in which the filament is thrown outward in the form of a spiral of large diameter (up to tens of cm) rotating at a rate 0.9?. The transition between the coiling and lariat modes is hysteretic with respect to variations in ?. In addition to the laboratory experiments, we will also present preliminary results of numerical calculations of the lariat mode based on a ``slender body'' model for a viscous filament with inertia.

Ribe, Neil; Badr, Sarah; Morris, Stephen

2009-11-01

253

The research of the conductive mechanism and properties of magnetorheological fluids  

NASA Astrophysics Data System (ADS)

We investigated the resistance response induced by the magnetic field in magnetorheological fluids, the resulting magnetization process alters the distribution of the ferromagnetic particles from unordered distribution to catenulate distribution. Consequently the electrical conductive property of the whole sample changes. A four-stage model has been built to describe the distinct characteristics of the variation of the magnetorheological fluids resistance with a sectional formalism, which is found in excellent agreement with the experimental results. Also, the application of the electrical properties of the magnetorheological fluids in the engineering field is discussed.

Chen, Xi; Zhu, Xiaoqiang; Xu, Zeyu; Lin, Yuanchang; He, Guotian

2013-06-01

254

Numerical prediction of fluid motion in the induction system and the cylinder in reciprocating engines  

SciTech Connect

This paper presents a multi-dimensional computer program for simulating fluid dynamics in reciprocating internal combustion engines. The numerical procedure uses a time-dependent implicit finite-difference approach in a general curvilinear coordinate system on a grid which may expand and contract with the motion of the intake valve and piston. In this program, special attention has been paid to take into account complex geometries: the computational domain includes the intake port and the cylinder, the motion and closure of the valve are described, the piston may contain a bowl. The intake process followed by compression in two- and three-dimensional direct injection four stroke diesel engine configurations are simulated. The results show that the program is applicable to characterize flow structure simultaneously in the intake port and the cylinder.

Paul, E.M.

1987-01-01

255

A Practice-Integrated Undergraduate Curriculum in Mechanical Engineering  

NSDL National Science Digital Library

Project-based and experiential learning is becoming increasingly important in engineering education. When recently surveyed, a majority of the students in a junior-year class at the University of Pennsylvania stated that they learned more from a particular course that had a strong lab component than from any other college class. This student belief may stem from the internal confirmation of understanding that hands-on work provides. Students seem to gain confidence when they are able to apply class material successfully to real-world systems, rather solving text book problems on paper. It is not yet clear where the critical learning takes place, whether in the lab or in the associated lecture, but it is obvious from our experience that laboratory work catalyzes student understanding and excitement about mechanical engineering. Based on student feedback and our belief in the value of project-based and experiential learning, we have developed a practice-integrated mechanical engineering curriculum that spans the full four-year undergraduate experience. Our goal is to ingrain theoretical concepts and develop independent student thinking by gradually incorporating design into laboratory activities; by exposing students to systems and applications before developing all of the relevant theoretical concepts; and by motivating students to appreciate the importance and relevance of the theory by directly applying it in projects.

2011-05-04

256

Mechanics of interstitial-lymphatic fluid transport: theoretical foundation and experimental validation  

Microsoft Academic Search

Interstitial fluid movement is intrinsically linked to lymphatic drainage. However, their relationship is poorly understood, and associated pathologies are mostly untreatable. In this work we test the hypothesis that bulk tissue fluid movement can be evaluated in situ and described by a linear biphasic theory which integrates the regulatory function of the lymphatics with the mechanical stresses of the tissue.

Melody A. Swartz; Arja Kaipainen; Paolo A. Netti; Christian Brekken; Yves Boucher; Alan J. Grodzinsky; Rakesh K. Jain

1999-01-01

257

Revisiting Newtonian and Non-Newtonian Fluid Mechanics Using Computer Algebra  

ERIC Educational Resources Information Center

|This article illustrates how a computer algebra system, such as Maple[R], can assist in the study of theoretical fluid mechanics, for both Newtonian and non-Newtonian fluids. The continuity equation, the stress equations of motion, the Navier-Stokes equations, and various constitutive equations are treated, using a full, but straightforward,…

Knight, D. G.

2006-01-01

258

Fundamental studies of fluid mechanics and stability in porous media. Progress report  

SciTech Connect

This report summarizes accomplished and proposed work for the fundamental studies of fluid mechanics and stability in porous media. Topics discussed include: viscous fingering in miscible displacements; polymer flow interactions in free shear layers of viscoelastic fluids; effect of nonmonotonic viscosity profiles on the stability of miscible displacements in porous media; and references. (JL)

Homsy, G.M.

1991-08-01

259

A Diffusion Tensor Imaging Tractography Algorithm Based on Navier–Stokes Fluid Mechanics  

Microsoft Academic Search

We introduce a fluid mechanics based tractography method for estimating the most likely connection paths between points in diffusion tensor imaging (DTI) volumes. We customize the Navier-Stokes equations to include information from the diffusion tensor and simulate an artificial fluid flow through the DTI image volume. We then estimate the most likely connection paths between points in the DTI volume

Nathan S. Hageman; Arthur W. Toga; Katherine L. Narr; David W. Shattuck

2009-01-01

260

Illustration of important mechanisms controlling mass transfer in supercritical fluid extraction  

Microsoft Academic Search

Supercritical fluid extraction profiles are presented for various model systems. The purpose is to illustrate some mechanisms encountered in supercritical fluid extraction by using simplified systems and also to give examples of how pre-extraction steps can be utilized to improve the mass-transfer rate. Extraction of clevidipine (a calcium antagonist) from different, allegedly inert materials, showed significant differences in extraction efficiency.

Erland Björklund; Mattias Järemo; Lennart Mathiasson; Jan Åke Jönsson; Lars Karlsson

1998-01-01

261

MECHANISMS OF FLUID SHEAR-INDUCED INHIBITION OF POPULATION GROWTH IN A RED-TIDE DINOFLAGELLATE  

EPA Science Inventory

Net population growth of some dinoflagellates is inhibited by fluid shear at shear stresses comparable with those generated during oceanic turbulence. Decreased net growth may occur through lowered cell division, increased mortality, or both. The dominant mechanism under various ...

262

Wavefront sensors for optical diagnostics in fluid mechanics: Application to heated flow, turbulence and droplet evaporation.  

National Technical Information Service (NTIS)

Optical measurement techniques are extremely useful in fluid mechanics because of their non-invasive nature. However, it is often difficult to separate measurement effects due to pressure, temperature and density in real flows. Using a variation of a Shac...

D. R. Neal T. J. O'Hern J. R. Torczynski M. E. Warren R. Shul

1993-01-01

263

Interactive Remote-Controlled Experiment for Instruction in Fluid Mechanics  

Microsoft Academic Search

Just as the Internet has transformed communication and scientific research over the last decade, it is changing industry, commerce, social exchange, and education all over the world. Today engineers control complex systems that may have components in widely separated geographic locations all remotely controlled over Internet. In education, new avenues and methods for enhancing the overall learning experience as well

M. Muste; A. Kruger; W. Eichinger; M. Wilson

2004-01-01

264

Effects of mechanical stimulation induced by compression and medium perfusion on cardiac tissue engineering.  

PubMed

Cardiac tissue engineering presents a challenge due to the complexity of the muscle tissue and the need for multiple signals to induce tissue regeneration in vitro. We investigated the effects of compression (1 Hz, 15% strain) combined with fluid shear stress (10(-2) -10(-1) dynes/cm(2) ) provided by medium perfusion on the outcome of cardiac tissue engineering. Neonatal rat cardiac cells were seeded in Arginine-Glycine-Aspartate (RGD)-attached alginate scaffolds, and the constructs were cultivated in a compression bioreactor. A daily, short-term (30 min) compression (i.e., "intermittent compression") for 4 days induced the formation of cardiac tissue with typical striation, while in the continuously compressed constructs (i.e., "continuous compression"), the cells remained spherical. By Western blot, on day 4 the expression of the gap junction protein connexin 43 was significantly greater in the "intermittent compression" constructs and the cardiomyocyte markers (?-actinin and N-cadherin) showed a trend of better preservation compared to the noncompressed constructs. This regime of compression had no effect on the proliferation of nonmyocyte cells, which maintained low expression level of proliferating cell nuclear antigen. Elevated secretion levels of basic fibroblast growth factor and transforming growth factor-? in the daily, intermittently compressed constructs likely attributed to tissue formation. Our study thus establishes the formation of an improved cardiac tissue in vitro, when induced by combined mechanical signals of compression and fluid shear stress provided by perfusion. PMID:22961835

Shachar, Michal; Benishti, Nessi; Cohen, Smadar

2012-10-18

265

Reaction Engineering International and Pacific Northwest Laboratory staff exchange: Addressing computational fluid dynamics needs of the chemical process industry  

SciTech Connect

Staff exchanges, such as the one described in this report, are intended to facilitate communications and collaboration among scientists and engineers at Department of Energy (DOE) laboratories, in US industry, and academia. Funding support for these exchanges is provided by the DOE, Office of Energy Research, Laboratory Technology Transfer Program. Funding levels for each exchange typically range from $20,000 to $40,000. The exchanges offer the opportunity for the laboratories to transfer technology and expertise to industry, gain a perspective to industry`s problems, and develop the basis for further cooperative efforts through Cooperative Research and Development Agreements (CRADAS) or other mechanisms. Information in this report on the staff exchange of the Pacific Northwest Laboratory (PNL) staff with Reaction Engineering International (REI) includes the significant accomplishments, significant problems, industry benefits realized, recommended follow-on work and potential benefit of that work. The objectives of this project were as follows: Work with REI to develop an understanding of the computational fluid dynamics (CFD) needs of the chemical process industry; assess the combined capabilities of the PNL and REI software analysis tools to address these needs; and establish a strategy for a future programmatically funded, joint effort to develop a new CFD tool for the chemical process industry.

Fort, J.A.

1995-07-01

266

Fluid Mechanics, Drag Reduction and Advanced Configuration Aeronautics  

Microsoft Academic Search

Paper discusses Advanced Aircraft configurational approaches, acrossthe speed range, which are either enabled, or greatly enhanced, by cleverFlow Control. Configurations considered include Channel Wings withcirculation control for VTOL [but non-hovering] operation with high cruisespeed, strut-braced CTOL transports with wing-tip engines and extensive[natural] laminar flow control, a midwing double fuselage CTOL approachutilizing several synergistic methods for drag-due-to-lift reduction,...

Dennis M. Bushnell

2000-01-01

267

Mechanical analysis and durability for a 3 kW Stirling engine  

Microsoft Academic Search

A 3 kW class Stirling engine, the NSO3T, has been developed for a gas-fired residential heat pump. The specifications and mechanical system of the engine, which is a deformed inline design with two pistons, are described. A mechanical analysis, using both experimental and computer analysis results, is presented. Also discussed are an improvement of the engine mechanical system and engine

N. Kagawa; M. Okuda; S. Nagatomo; S. Ichikawa; M. Sakamoto

1989-01-01

268

Design of a biaxial mechanical loading bioreactor for tissue engineering.  

PubMed

We designed a loading device that is capable of applying uniaxial or biaxial mechanical strain to a tissue engineered biocomposites fabricated for transplantation. While the device primarily functions as a bioreactor that mimics the native mechanical strains, it is also outfitted with a load cell for providing force feedback or mechanical testing of the constructs. The device subjects engineered cartilage constructs to biaxial mechanical loading with great precision of loading dose (amplitude and frequency) and is compact enough to fit inside a standard tissue culture incubator. It loads samples directly in a tissue culture plate, and multiple plate sizes are compatible with the system. The device has been designed using components manufactured for precision-guided laser applications. Bi-axial loading is accomplished by two orthogonal stages. The stages have a 50 mm travel range and are driven independently by stepper motor actuators, controlled by a closed-loop stepper motor driver that features micro-stepping capabilities, enabling step sizes of less than 50 nm. A polysulfone loading platen is coupled to the bi-axial moving platform. Movements of the stages are controlled by Thor-labs Advanced Positioning Technology (APT) software. The stepper motor driver is used with the software to adjust load parameters of frequency and amplitude of both shear and compression independently and simultaneously. Positional feedback is provided by linear optical encoders that have a bidirectional repeatability of 0.1 ?m and a resolution of 20 nm, translating to a positional accuracy of less than 3 ?m over the full 50 mm of travel. These encoders provide the necessary position feedback to the drive electronics to ensure true nanopositioning capabilities. In order to provide the force feedback to detect contact and evaluate loading responses, a precision miniature load cell is positioned between the loading platen and the moving platform. The load cell has high accuracies of 0.15% to 0.25% full scale. PMID:23644779

Bilgen, Bahar; Chu, Danielle; Stefani, Robert; Aaron, Roy K

2013-04-25

269

A review of interaction mechanisms in fluid-solid flows  

SciTech Connect

Multiphase flows have become the subject of considerable attention because of their importance in many industrial applications, such as fluidized beds, pneumatic transport of solids, coal combustion, etc. Fundamental research into the nature of pneumatic transport has made significant progress in identifying key parameters controlling the characteristics of these processes. The emphasis of this study is on a mixture composed of spherical particles of uniform size and a linearly viscous fluid. Section 1 introduces our approach and the importance of this study. In Section 2, the dynamics of a single particle as studied in classical hydrodynamics and fluid dynamics is presented. This has been a subject of study for more than 200 years. In Section 3, we review the literature for the constitutive relations as given in multiphase studies, i.e., generalization of single particle and as given in literature concerning the continuum theories of mixtures or multicomponent systems. In Section 4, a comparison between these representations and the earlier approach, i.e., forces acting on a single particle will be made. The importance of flow regimes, particle concentration, particle size and shape, rotation of the particle, effect of solid walls, etc. are discussed. 141 refs.

Johnson, G.; Rajagopal, K.R. (Pittsburgh Univ., PA (USA). Dept. of Mechanical Engineering); Massoudi, M. (USDOE Pittsburgh Energy Technology Center, PA (USA))

1990-09-01

270

Wear mechanisms in moderate temperature gasoline engine service  

SciTech Connect

The mechanism of overhead valve train wear in moderate to low temperature service was studied using a modified fired V-D test and a motored V-D cam and cam-follower rig. High wear and low wear used oils from the fired test gave the correct relative wear in the motored test, indicating the motored test in a valid tool for studying wear mechanisms. Key factors affecting valve train wear were isolated and selectively introduced in a series of motored engine tests. Results from this study showed the expected increase in wear with a decrease in viscosity of unformulated lubricants. Added zinc dialkyldithiophosphate (ZDDP) reduced wear in a low viscosity lubricant and a used oil as anticipated. A high detergent, high wear oil, in an unused state, did not produce significant wear in the motored test even if all of the ZDDP was removed. Significant wear resulted only after exhaust gases (simulated blowby) were fed into the motored engine sump containing the high wear oil. Laboratory simulation of blowby effects showed the importance of wear resulting from oil aging by chemical reactions between the lubricant and blowby gases. This effect is important even when the viscosity of the lubricant is otherwise sufficient to preclude wear. Active ZDDP depletion by thermal and oxidative routes contributes to wear. Viscosity losses in the Sequence V-D test and in the fired test were large due to fuel dilution and Viscosity Index Improver shear which can lead to further increases in wear.

West, C.T.; Passut, C.A.; Chamot, E.

1986-01-01

271

Wear Mechanism Analysis of Engine Exhaust Valve Seats with a Laboratory Simulator  

Microsoft Academic Search

Engine valve seat wear affects engine performance. A common goal for both valve and engine manufacturers is to improve both valve quality and life. By performing tests on a simulator which is verified to be capable of simulating an engine operating environment, the wear resistance of various valve materials is ranked, and the wear mechanisms are investigated.Four commonly used exhaust

R. Zhao; G. C. Barber; Y. S. Wang; J. E. Larson

1997-01-01

272

Breakdown voltage determination of gaseous and near cryogenic fluids with application to rocket engine ignition  

NASA Astrophysics Data System (ADS)

Liquid rocket engines extensively use spark-initiated torch igniters for ignition. As the focus shifts to longer missions that require multiple starts of the main engines, there exists a need to solve the significant problems associated with using spark-initiated devices. Improving the fundamental understanding of predicting the required breakdown voltage in rocket environments along with reducing electrical noise is necessary to ensure that missions can be completed successfully. To better understand spark ignition systems and add to the fundamental research on spark development in rocket applications, several parameter categories of interest were hypothesized to affect breakdown voltage: (i) fluid, (ii) electrode, and (iii) electrical. The fluid properties varied were pressure, temperature, density and mass flow rate. Electrode materials, insert electrode angle and spark gap distance were the electrode properties varied. Polarity was the electrical property investigated. Testing how breakdown voltage is affected by each parameter was conducted using three different isolated insert electrodes fabricated from copper and nickel. A spark plug commonly used in torch igniters was the other electrode. A continuous output power source connected to a large impedance source and capacitance provided the pulsing potential. Temperature, pressure and high voltage measurements were recorded for the 418 tests that were successfully completed. Nitrogen, being inert and similar to oxygen, a propellant widely used in torch igniters, was used as the fluid for the majority of testing. There were 68 tests completed with oxygen and 45 with helium. A regression of the nitrogen data produced a correction coefficient to Paschen's Law that predicts the breakdown voltage to within 3000 volts, better than 20%, compared to an over prediction on the order of 100,000 volts using Paschen's Law. The correction coefficient is based on the parameters most influencing breakdown voltage: fluid density, spark gap distance, electrode angles, electrode materials and polarity. The research added to the fundamental knowledge of spark development in rocket ignition applications by determining the parameters that most influence breakdown voltage. Some improvements to the research should include better temperature measurements near the spark gap, additional testing with oxygen and testing with fuels of interest such as hydrogen and methane.

Nugent, Nicholas Jeremy

273

Computational Thermal, Chemical, Fluid, and Solid Mechanics for Geosystems Management.  

National Technical Information Service (NTIS)

This document summarizes research performed under the SNL LDRD entitled - Computational Mechanics for Geosystems Management to Support the Energy and Natural Resources Mission. The main accomplishment was development of a foundational SNL capability for c...

B. Carnes C. F. Jove-Colon D. Z. Turner J. R. Red-Horse M. Mesh N. Alger P. L. Hopkins S. Davison S. R. Subia

2011-01-01

274

Continual improvement and assessment plan for Mechanical Engineering Programme in UNITEN  

Microsoft Academic Search

This paper describes the continuous quality improvement (CQI) process plan that was developed and implemented by the Department of Mechanical Engineering (DME), Universiti Tenaga Nasional (UNITEN), Malaysia for its Bachelor of Mechanical Engineering Programme. The plan is part of the Outcome-Based Education (OBE) system that is required by the Engineering Accreditation Council (EAC) of Malaysia. DME has implemented OBE approach

Adzly Anuar; Norshah Hafeez Shuaib; Khairul Salleh Mohamed Sahari; Izham Zainal Abidin

2009-01-01

275

Computational Fluid Dynamic Modelling a Heavy-Duty Compression-Ignition Engine Fuelled with Diesel and Gasoline-Like Fuels  

Microsoft Academic Search

This paper presents a comprehensive investigation of a compression—ignition (CI) heavy-duty engine fuelled with diesel and gasoline-like fuels. A state-of-the-art engine computational fluid dynamics (CFD) tool was used to explore the influences of the physical and chemical properties of diesel and gasoline-like fuels (no. 91 gasoline and E10) on spray development, auto-ignition and combustion processes, and pollutant formation. The CFD

Y Shi; Y Wang; R D Reitz

2010-01-01

276

A literature review on mechanisms and models for the coalescence process of fluid particles  

Microsoft Academic Search

This paper presents a literature review on the mechanisms and models of coalescence of fluid particles. For the mechanisms, five categories are summarized, namely, turbulence fluctuation, viscous shear stress, capture in turbulent eddies, buoyancy and wake interaction. The models for collision frequency and coalescence efficiency as well as contact and drainage times available in literature are reviewed thoroughly. The development

Yixiang Liao; Dirk Lucas

2010-01-01

277

Mechanics of layered anisotropic poroelastic media with applications to effective stress for fluid permeability  

SciTech Connect

The mechanics of vertically layered porous media has some similarities to and some differences from the more typical layered analysis for purely elastic media. Assuming welded solid contact at the solid-solid interfaces implies the usual continuity conditions, which are continuity of the vertical (layering direction) stress components and the horizontal strain components. These conditions are valid for both elastic and poroelastic media. Differences arise through the conditions for the pore pressure and the increment of fluid content in the context of fluid-saturated porous media. The two distinct conditions most often considered between any pair of contiguous layers are: (1) an undrained fluid condition at the interface, meaning that the increment of fluid content is zero (i.e., {delta}{zeta} = 0), or (2) fluid pressure continuity at the interface, implying that the change in fluid pressure is zero across the interface (i.e., {delta}p{sub f} = 0). Depending on the types of measurements being made on the system and the pertinent boundary conditions for these measurements, either (or neither) of these two conditions might be directly pertinent. But these conditions are sufficient nevertheless to be used as thought experiments to determine the expected values of all the poroelastic coefficients. For quasi-static mechanical changes over long time periods, we expect drained conditions to hold, so the pressure must then be continuous. For high frequency wave propagation, the pore-fluid typically acts as if it were undrained (or very nearly so), with vanishing of the fluid increment at the boundaries being appropriate. Poroelastic analysis of both these end-member cases is discussed, and the general equations for a variety of applications to heterogeneous porous media are developed. In particular, effective stress for the fluid permeability of such poroelastic systems is considered; fluid permeabilities characteristic of granular media or tubular pore shapes are treated in some detail, as are permeabilities of some of the simpler types of fractured materials.

Berryman, J.G.

2010-06-01

278

Mechanism of Protein Kinetic Stabilization by Engineered Disulfide Crosslinks  

PubMed Central

The impact of disulfide bonds on protein stability goes beyond simple equilibrium thermodynamics effects associated with the conformational entropy of the unfolded state. Indeed, disulfide crosslinks may play a role in the prevention of dysfunctional association and strongly affect the rates of irreversible enzyme inactivation, highly relevant in biotechnological applications. While these kinetic-stability effects remain poorly understood, by analogy with proposed mechanisms for processes of protein aggregation and fibrillogenesis, we propose that they may be determined by the properties of sparsely-populated, partially-unfolded intermediates. Here we report the successful design, on the basis of high temperature molecular-dynamics simulations, of six thermodynamically and kinetically stabilized variants of phytase from Citrobacter braakii (a biotechnologically important enzyme) with one, two or three engineered disulfides. Activity measurements and 3D crystal structure determination demonstrate that the engineered crosslinks do not cause dramatic alterations in the native structure. The inactivation kinetics for all the variants displays a strongly non-Arrhenius temperature dependence, with the time-scale for the irreversible denaturation process reaching a minimum at a given temperature within the range of the denaturation transition. We show this striking feature to be a signature of a key role played by a partially unfolded, intermediate state/ensemble. Energetic and mutational analyses confirm that the intermediate is highly unfolded (akin to a proposed critical intermediate in the misfolding of the prion protein), a result that explains the observed kinetic stabilization. Our results provide a rationale for the kinetic-stability consequences of disulfide-crosslink engineering and an experimental methodology to arrive at energetic/structural descriptions of the sparsely populated and elusive intermediates that play key roles in irreversible protein denaturation.

Sanchez-Romero, Inmaculada; Ariza, Antonio; Wilson, Keith S.; Skj?t, Michael; Vind, Jesper; De Maria, Leonardo; Skov, Lars K.; Sanchez-Ruiz, Jose M.

2013-01-01

279

Application of Wave Mechanics Theory to Fluid Dynamics Problems: Boundary Layer on a Circular Cylinder Including Turbulence.  

National Technical Information Service (NTIS)

The application of the elements of quantum (wave) mechanics to some special problems in the field of macroscopic fluid dynamics is discussed. Emphasis is placed on the flow of a viscous, incompressible fluid around a circular cylinder. The following subje...

M. Z. V. Krzywoblocki

1974-01-01

280

Fluid Mechanics Produces Conflicting Constraints During Olfactory Navigation  

NASA Astrophysics Data System (ADS)

Blue crabs foraging in turbulent odor plumes must acquire useful chemical cues in addition to responding to fluid forces imposed on their body. The drag force experienced by blue crabs is shown to be a function of the body orientation angle relative to the flow (maximum at 0 deg and minimum at 90 degrees). Crabs turn their body to an orientation (near 90 deg) that minimizes the drag force in high-speed flows with and without odor present in order to lower the cost of locomotion. At lower flow speeds they turn to a higher drag orientation (near 50 deg) only in the presence of odor. At a smaller relative orientation angle to the flow, the antennules receive more direct contact with the advected odor filaments, which mediate upstream movement, and the appendage chemosensors are separated in the cross-stream direction, which facilitates a useful bilateral comparison. Thus, blue crabs appear to accept a higher drag force (and cost of locomotion) in order to place their antennules and appendages in positions to collect useful chemosensory information. They do so only at low flow speeds, which suggests that they weigh the potential benefits to the costs.

Webster, D. R.; Weissburg, M. J.

2002-11-01

281

Critical Performance of Turbopump Mechanical Elements for Rocket Engine  

NASA Astrophysics Data System (ADS)

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.

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

282

Physiologic mechanisms effecting circulatory and body fluid losses in weightlessness as shown by mathematical modeling.  

PubMed

The mechanisms causing large body water losses in weightlessness are not clear. It has long been considered that a central volume expansion drives the physiologic adaptation to a reduced total blood volume, with normal blood composition eventually regained. However, inflight venous pressure measures suggest that central volume expansion in weightlessness may be very transient, or that considerable cardiovascular adaptation to fluid shifts occurs on the ground while astronauts wait in the semi-supine pre-launch position. If a central volume stimulus does not persist, other mechanisms must drive the adaptation of circulation to a reduced blood volume and account for body fluid losses. Recent results from the SLS-1 mission suggest that body fluid volumes do not simply decline to new equilibria but that they decrease to a low point, then undergo some recovery. Similar "under-shoots" of body fluid volumes have also been shown in computer simulations, providing confidence in the validity of the model. The purpose of this study was to examine the mechanisms which could explain the loss of body fluids in weightlessness and how a cardiovascular preadaptation countermeasure we previously tested ameliorated body fluid losses. It is assumed that the physiology of head down tilt (HDT) provides a reasonably accurate analog of weightless exposure. PMID:11537415

Simanonok, K E; Srinivasan, R S; Charles, J B

1993-01-01

283

Mechanical properties of human amniotic fluid stem cells using nanoindentation.  

PubMed

The aim of this study was to obtain nanomechanical properties of living cells focusing on human amniotic fluid stem (hAFS) cell using nanoindentation techniques. We modified the conventional method of atomic force microscopy (AFM) in aqueous environment for cell imaging and indentation to avoid inherent difficulties. Moreover, we determined the elastic modulus of murine osteoblast (OB6) cells and hAFS cells at the nucleus and cytoskeleton using force-displacement curves and Hertz theory. Since OB6 cell line has been widely used, it was selected to validate and compare the obtained results with the previous research studies. As a result, we were able to capture high resolution images through utilization of the tapping mode without adding protein or using fixation methods. The maximum depth of indentation was kept below 15% of the cell thickness to minimize the effect of substrate hardness. Nanostructural details on the surface of cells were visualized by AFM and fluorescence microscopy. The cytoskeletal fibers presented remarkable increase in elastic modulus as compared with the nucleus. Furthermore, our results showed that the elastic modulus of hAFS cell edge (31.6 kPa) was lower than that of OB6 cell edge (42.2 kPa). In addition, the elastic modulus of nucleus was 13.9 kPa for hAFS cell and 26.9 kPa for OB6 cells. Differences in cell elastic modulus possibly resulted from the type and number of actin cytoskeleton organization in these two cell types. PMID:23628151

Aryaei, Ashkan; Jayasuriya, Ambalangodage C

2013-04-28

284

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

ERIC Educational Resources Information Center

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…

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

285

Fluid Flow Mechanisms in the Serpentine Mud Volcanoes of the Mariana Forearc  

NASA Astrophysics Data System (ADS)

Understanding the magnitude, direction, and duration of fluid flow in the serpentine mud volcanoes of the Marianna forearc helps us place constraints on the timing and emplacement of the extruded muds. The muds were extruded along conduits in forearc faults and can be up to 2 km high and 30 km across at their base. We are incorporating measurements taken during Ocean Drilling Program Cruise Leg 195 in numerical models to investigate three possible mechanisms of fluid flow in the serpentine muds. These mechanisms are direct vertical flow along a joint or conduit at the base of the mud volcano; flow driven by consolidation due to additional emplacement of muds on the volcano surface; and density-driven flow, in which denser and cooler seawater intrudes into the mud volcano and displaces the less dense mud pore fluids. Direct vertical flow. The mechanism of flow along a vertical joint or conduit in the mud volcano is the simplest conceptually. In this model, a small vertical conduit extends from a fracture or fault at the base of the mud volcano to its surface. Fluid flow in the mud volcano is primarily through this conduit where it discharges at the volcano summit. This flow need not be episodic. Two types of physical measurements--shear strength and temperature--made during ODP Cruise Leg 195 make this model unlikely. The shear strength of the muds was measured to be 90 kPa, and this strength places an upper bound on the stress the muds can bear. To hold open such a conduit at a depth of 2 km, the effective stresses must either be very low, because of high fluid pressures at the volcano base, or the strength of the muds must be much larger than measured. Temperatures of fluids near the summit of the volcano were lower than would be expected if the fluids rose quickly from the crust-mantle boundary. Because the values of the thermal and hydraulic diffusivity for the bulk muds are approximately 10-7 m2/s, there should be relatively little heat lost to thermal diffusion while the fluids quickly rise through the conduit; the result should be higher than our measured fluid temperatures. Consolidation-driven flow. Flow may result from consolidation of the volcano as muds are pushed upward from a fault at the base of the volcano, through the center of the volcano, and then emplaced on the volcano's surface. The weight of the newly emplaced muds cause fluid pressures to rise inside the volcano. As the fluid flows in response to this pressure increase, consolidation of the volcano also occurs. The amount of fluid flow will steadily decrease until the fluid pressures once again are in equilibrium. The approximate time of consolidation for a mud volcano 2 km in height and 30 km across at its base is 1 million years. Density-driven flow. Inflow of denser seawater into the serpentine muds could drive fluid flow. When the serpentine muds are emplaced, there is a gravity inversion of less dense pore fluids in the muds beneath the denser seawater. Through this density contrast, the cooler, denser seawater would intrude into the flanks of the volcano first and force the warmer and fresher pore fluid out of the volcano summit. This mechanism would produce pore fluids more similar to seawater on the flanks of the mud volcano, and fresher pore fluids near the summit, as was observed at Conical seamount during ODP Leg 125. The timescale of saltwater intrusion is similar to that of consolidation.

Hart, D. J.

2002-12-01

286

Overview of heat transfer and fluid flow problem areas encountered in stirling engine modeling  

Microsoft Academic Search

NASA Lewis Research Center has been managing Stirling engine development programs for over a decade. In addition to contractual programs, this work has included in-house engine testing and development of engine computer models. Attempts to validate Stirling engine computer models with test data have demonstrated that engine thermodynamic losses need better characterization. Various Stirling engine thermodynamic losses and efforts that

Tew; R. C. Jr

1988-01-01

287

The Effects of Fluid Absorption on the Mechanical Properties of Joint Prostheses Components  

NASA Astrophysics Data System (ADS)

Ultra-high-molecular-weight polyethylene (UHMWPE) is the material playing the role of cartilage in human prosthetic joints. Wear debris from UHMWPE is a common reason for joint arthroplasty failure, and the exact mechanism responsible for wear remains an area of investigation. In this study, the microstructure of UHMWPE was examined as a function of fluid absorption. Samples with varying exposure to e-beam radiation (as part of the manufacturing process) were soaked for forty days in saline or artificial synovial fluid, under zero or 100 lbs load. Samples were then tensile-tested according to ASTM D-3895. The post-stressed material was then examined by transmission electron microscopy to evaluate the molecular response to stress, which correlates with macroscopic mechanical properties. Three parameters of the crystalline lamellae were measured: thickness, stacking ratio, and alignment to stress direction. Results indicate that fluid absorption does affect the mechanical properties of UHMWPE at both the microscopic and microscopic levels. )

Yarbrough, David; Viano, Ann

2010-02-01

288

Smart multifunctional fluids for lithium ion batteries: enhanced rate performance and intrinsic mechanical protection.  

PubMed

Lithium ion batteries are attractive power sources for the consumer electronics market and are being aggressively developed for road transportation. Nevertheless, issues with safety and reliability need to be solved prior to the large-scale uptake of these batteries. There have recently been significant development and assessment of materials with resistance to mechanical abuse, with the aims of reinforcing the battery and preventing puncturing during a crash. Most of the work on battery mechanical safety has concentrated on the external packaging of batteries, with little attention being paid to the enclosed electrolyte. We report on smart multifunctional fluids that act as both highly conductive electrolytes and intrinsic mechanical protectors for lithium ion batteries. These fluids exhibit a shear thickening effect under pressure or impact and thus demonstrate excellent resistance to crushing. Also, the fluids show higher ionic conductivities and comparable redox stability windows to the commercial liquid electrolytes. PMID:23962885

Ding, Jie; Tian, Tongfei; Meng, Qing; Guo, Zaiping; Li, Weihua; Zhang, Peng; Ciacchi, Fabio T; Huang, Jewel; Yang, Wenrong

2013-08-21

289

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

ERIC Educational Resources Information Center

|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…

Human Engineering Inst., Cleveland, OH.

290

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

Microsoft Academic Search

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

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

2008-01-01

291

Magnetorheological fluid template for basic studies of mechanical-chemical effects during polishing  

NASA Astrophysics Data System (ADS)

We developed a new magnetorheological (MR) fluid for studying the relative contributions of mechanics and chemistry in polishing hard materials. The base carrier fluid is a mixture of two non-aqueous liquids. At conventional carbonyl iron (CI) magnetic particle concentrations, removal rates with this formulation were unacceptably low for the polycrystalline optical ceramic aluminum oxynitride (ALON). We overcame this problem by creating a high magnetic solids concentration suspension consisting of a blend of large and small CI particles. Our test bed for experiments was a magnetorheological finishing (MRF) spot-taking machine (STM) that can only polish spots into a non-rotating part. We demonstrated that, using this new MR fluid formulation, we could substantially increase peak removal rates on ALON with small additions of nonmagnetic, nanodiamond abrasives. Material removal with this fluid was assumed to be predominately driven by mechanics. With the addition of small amounts of DI water to the base fluid containing nanodiamonds, the peak removal rate showed an additional increase, presumably due to the altered fluid rheology and possibly chemical interactions. It is possible, however, that this result is due to increased fluid viscosity as well. Interestingly, the microtexture on the surfaces of the ALON grains (albeit-two different ALON parts) showed distinctly different features when spotted with nanodiamonds or with nanodiamonds and water, and an understanding of this phenomenon is the goal of future work. In this paper we describe the difficult fluid viscosity issues that were addressed in creating a viable, high removal rate, non-aqueous MR fluid template that could be pumped in the STM for several days of experiments.

Miao, Chunlin; Bristol, Kirk M.; Marino, Anne E.; Shafrir, Shai N.; DeGroote, Jessica E.; Jacobs, Stephen D.

2007-09-01

292

The Mechanical Coupling of Fluid-Filled Granular Material Under Shear  

NASA Astrophysics Data System (ADS)

The coupled mechanics of fluid-filled granular media controls the physics of many Earth systems, for example saturated soils, fault gouge, and landslide shear zones. It is well established that when the pore fluid pressure rises, the shear resistance of fluid-filled granular systems decreases, and, as a result, catastrophic events such as soil liquefaction, earthquakes, and accelerating landslides may be triggered. Alternatively, when the pore pressure drops, the shear resistance of these geosystems increases. Despite the great importance of the coupled mechanics of grain-fluid systems, the basic physics that controls this coupling is far from understood. Fundamental questions that must be addressed include: what are the processes that control pore fluid pressurization and depressurization in response to deformation of the granular skeleton? and how do variations of pore pressure affect the mechanical strength of the grains skeleton? To answer these questions, a formulation for the pore fluid pressure and flow has been developed from mass and momentum conservation, and is coupled with a granular dynamics algorithm that solves the grain dynamics, to form a fully coupled model. The pore fluid formulation reveals that the evolution of pore pressure obeys viscoelastic rheology in response to pore space variations. Under undrained conditions elastic-like behavior dominates and leads to a linear relationship between pore pressure and overall volumetric strain. Viscous-like behavior dominates under well-drained conditions and leads to a linear relationship between pore pressure and volumetric strain rate. Numerical simulations reveal the possibility of liquefaction under drained and initially over-compacted conditions, which were often believed to be resistant to liquefaction. Under such conditions liquefaction occurs during short compactive phases that punctuate the overall dilative trend. In addition, the previously recognized generation of elevated pore pressure under undrained compactive conditions is observed. Simulations also show that during liquefaction events stress chains are detached, the external load becomes completely supported by the pressurized pore fluid, and shear resistance vanishes.

Goren, L.; Aharonov, E.; Sparks, D.; Toussaint, R.

2011-12-01

293

Separating Fluid Shear Stress from Acceleration during Vibrations in Vitro: Identification of Mechanical Signals Modulating the Cellular Response  

PubMed Central

The identification of the physical mechanism(s) by which cells can sense vibrations requires the determination of the cellular mechanical environment. Here, we quantified vibration-induced fluid shear stresses in vitro and tested whether this system allows for the separation of two mechanical parameters previously proposed to drive the cellular response to vibration – fluid shear and peak accelerations. When peak accelerations of the oscillatory horizontal motions were set at 1g and 60Hz, peak fluid shear stresses acting on the cell layer reached 0.5Pa. A 3.5-fold increase in fluid viscosity increased peak fluid shear stresses 2.6-fold while doubling fluid volume in the well caused a 2-fold decrease in fluid shear. Fluid shear was positively related to peak acceleration magnitude and inversely related to vibration frequency. These data demonstrated that peak shear stress can be effectively separated from peak acceleration by controlling specific levels of vibration frequency, acceleration, and/or fluid viscosity. As an example for exploiting these relations, we tested the relevance of shear stress in promoting COX-2 expression in osteoblast like cells. Across different vibration frequencies and fluid viscosities, neither the level of generated fluid shear nor the frequency of the signal were able to consistently account for differences in the relative increase in COX-2 expression between groups, emphasizing that the eventual identification of the physical mechanism(s) requires a detailed quantification of the cellular mechanical environment.

Uzer, Gunes; Manske, Sarah L; Chan, M Ete; Chiang, Fu-Pen; Rubin, Clinton T; Frame, Mary D; Judex, Stefan

2012-01-01

294

Effects of freezing-induced cell-fluid-matrix interactions on the cells and extracellular matrix of engineered tissues  

PubMed Central

The two most significant challenges for successful cryopreservation of engineered tissues (ETs) are preserving tissue functionality and controlling highly tissue-type dependent preservation outcomes. In order to address these challenges, freezing-induced cell-fluid-matrix interactions should be understood, which determine the post-thaw cell viability and extracellular matrix (ECM) microstructure. However, the current understanding of this tissue-level biophysical interaction is still limited. In this study, freezing-induced cell-fluid-matrix interactions and their impact on the cells and ECM microstructure of ETs were investigated using dermal equivalents as a model ET. The dermal equivalents were constructed by seeding human dermal fibroblasts in type I collagen matrices with varying cell seeding density and collagen concentration. While these dermal equivalents underwent an identical freeze/thaw condition, their spatiotemporal deformation during freezing, post-thaw ECM microstructure, and cellular level cryoresponse were characterized. The results showed that the extent and characteristics of freezing-induced deformation were significantly different among the experimental groups, and the ETs with denser ECM microstructure experienced a larger deformation. The magnitude of the deformation was well correlated to the post-thaw ECM structure, suggesting that the freezing-induced deformation is a good indicator of post-thaw ECM structure. A significant difference in the extent of cellular injury was also noted among the experimental groups, and it depended on the extent of freezing-induced deformation of the ETs and the initial cytoskeleton organization. These results suggest that the cells have been subjected to mechanical insult due to the freezing-induced deformation as well as thermal insult. These findings provide insight on tissue-type dependent cryopreservation outcomes, and can help to design and modify cryopreservation protocols for new types of tissues from a pre-developed cryopreservation protocol.

Teo, Ka Yaw; DeHoyos, Tenok O.; Dutton, J. Craig; Grinnell, Frederick; Han, Bumsoo

2011-01-01

295

Fluid Mechanics of Cellulose Fiber Suspensions Using MRI  

NASA Astrophysics Data System (ADS)

Efficient processing of fibrous biomass requires understanding the mechanics of fiber suspensions having large particle sizes of biomass particles, fast settling, and entanglements. Direct imaging of velocity profiles using magnetic resonance imaging provides a way of characterizing flow in the presence of such non-idealities. We found a strong influence of fiber length, concentrations and flow rates on velocity profiles and pressure drops. We map different regions in the concentration-velocity plane that serve as a guide to decide whether or not to use generalized newtonian rheological models. The concentration effects were best described by the use of a crowding number, with large changes in pressure and velocity profiles occurring in a narrow range of crowding numbers. Qualitative differences between the behavior of the long fibers and the short and medium fibers demonstrate a strong effect of fiber aspect ratio on rheology.

Powell, Robert; Lavenson, David; Tozzi, Emilio; McCarthy, Michael

2010-11-01

296

Mechanical and flow excited vibrations of elastic plates and cylindrical shells in dense fluids  

NASA Astrophysics Data System (ADS)

Mechanical and flow excited vibrations of elastic plates and cylindrical shells in dense fluids are presented. The perturbation method is used to connect the basic equations in fluid mechanics and acoustics. A computer model based on a boundary fitted coordinate transformation is used to solve the two dimensional incompressible viscous time dependent fluid flow problem. Numerical results for flow over vibrating plates and flow across vibrating cylindrical shells are presented. Several fluid acoustic solid interaction problems are addressed using a generic block diagram model. These problems include both viscous and inviscid flows over elastic plates and shells. The emphasis was to determine the near field surface pressure distribution on the elastic vibrators. The surface pressure for the forced vibration of elastic plates in contact with inviscid fluid flow is predicted using time and wavenumber domain approaches. The surface pressure on an elastic plate for the coupled fluid plate problem was addressed through analytical and numerical approaches. The surface pressure on a cylindrical shell with a specified radial excitation without flow is addressed by a modal expansion technique.

Li, Dong-Jye

297

Effects of Initial Seeding Density and Fluid Perfusion Rate on Formation of Tissue-Engineered Bone  

PubMed Central

We describe a novel bioreactor system for tissue engineering of bone that enables cultivation of up to six tissue constructs simultaneously, with direct perfusion and imaging capability. The bioreactor was used to investigate the relative effects of initial seeding density and medium perfusion rate on the growth and osteogenic differentiation patterns of bone marrow–derived human mesenchymal stem cells (hMSCs) cultured on three-dimensional scaffolds. Fully decellularized bovine trabecular bone was used as a scaffold because it provided suitable “biomimetic” topography, biochemical composition, and mechanical properties for osteogenic differentiation of hMSCs. Trabecular bone plugs were completely denuded of cellular material using a serial treatment with hypotonic buffers and detergents, seeded with hMSCs, and cultured for 5 weeks. Increasing seeding density from 30×106 cells/mL to 60×106 cells/mL did not measurably influence the characteristics of tissue-engineered bone, in contrast to an increase in the perfusion rate from 100 ?ms?1 to 400 ?ms?1, which radically improved final cell numbers, cell distributions throughout the constructs, and the amounts of bone proteins and minerals. Taken together, these findings suggest that the rate of medium perfusion during cultivation has a significant effect on the characteristics of engineered bone.

GRAYSON, WARREN L.; BHUMIRATANA, SARINDR; CANNIZZARO, CHRISTOPHER; CHAO, P.-H. GRACE; LENNON, DONALD P.; CAPLAN, ARNOLD I.; VUNJAK-NOVAKOVIC, GORDANA

2009-01-01

298

Using Functional Tissue Engineering and Bioreactors to Mechanically Stimulate Tissue-Engineered Constructs  

PubMed Central

Bioreactors precondition tissue-engineered constructs (TECs) to improve integrity and hopefully repair. In this paper, we use functional tissue engineering to suggest criteria for preconditioning TECs. Bioreactors should (1) control environment during mechanical stimulation; (2) stimulate multiple constructs with identical or individual waveforms; (3) deliver precise displacements, including those that mimic in vivo activities of daily living (ADLs); and (4) adjust displacement patterns based on reaction loads and biological activity. We apply these criteria to three bioreactors. We have placed a pneumatic stimulator in a conventional incubator and stretched four constructs in each of five silicone dishes. We have also programmed displacement-limited stimuli that replicate frequencies and peak in vivo patellar tendon (PT) strains. Cellular activity can be monitored from spent media. However, our design prevents direct TEC force measurement. We have improved TEC stiffness as well as PT repair stiffness and shown correlations between the two. We have also designed an incubator to fit within each of two electromagnetic stimulators. Each incubator provides cell viability like a commercial incubator. Multiple constructs are stimulated with precise displacements that can mimic ADL strain patterns and record individual forces. Future bioreactors could be further improved by controlling and measuring TEC displacements and forces to create more functional tissues for surgeons and their patients.

Hunter, Shawn A.; Chokalingam, Kumar; Cordray, Michael J.; Shearn, Jason; Juncosa-Melvin, Natalia; Nirmalanandhan, Sanjit; Jain, Abhishek

2009-01-01

299

Automotive Engines; Automotive Mechanics I: 9043.03.  

ERIC Educational Resources Information Center

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…

Dade County Public Schools, Miami, FL.

300

Fluid motion within the cylinder of internal combustion engines - The 1986 Freeman Scholar Lecture  

Microsoft Academic Search

The flow field within the cylinder of internal combustion engines is the most important factor controlling the combustion process. Thus it has a major impact on engine operation. This paper reviews those aspects of gas motion into, within, and out of the engine cylinder that govern the combustion characteristics and breathing capabilities of spark-ignition engines and compression-ignition or diesel engines.

John B. Heywood

1987-01-01

301

Dynamic response analysis of a solar powered heliotropic fluid-mechanical drive system  

NASA Astrophysics Data System (ADS)

This paper provides a summary of work performed during the design, construction, and subsequent analysis of a solar powered tracking mechanism. The mechanism utilizes basic mechanical and thermodynamic principles in its construction and operation. Data taken during the course of the research and reported in this paper reveal that with a particular combination of system components and working fluid, a high degree of accuracy and wind stability can be achieved with this device when used to drive large concentrating solar collectors. The tracking mechanism was found to be fully self-correcting during normal daily operation and to reorient itself to the morning sun.

Cope, N. A.; Ingley, H. A.; Farber, E. A.; Morrison, C. A.

302

Overview of Heat Transfer and Fluid Flow Problem Areas Encountered in Stirling Engine Modeling.  

National Technical Information Service (NTIS)

NASA Lewis Research Center has been managing Stirling engine development programs for over a decade. In addition to contractual programs, this work has included in-house engine testing and development of engine computer models. Attempts to validate Stirli...

R. C. Tew

1988-01-01

303

Mechanical properties of protein?stabilized starch?based supercritical fluid extrudates  

Microsoft Academic Search

Mechanical properties of starch?based supercritical fluid extrusion (SCFX) extrudates were correlated to their structure. Thermosetting ingredients were added to the feed and the extrudate was dried to set the expanded structure. Compared to whey protein concentrate with 34% protein (WPC?34), addition of egg white (EW) gave a softer skin and a fragile but well formed cellular structure. For drying between

B. K. Gogoi; S. H. Alavi; S. S. H. Rizvi

2000-01-01

304

Fast Prediction of HCCi Combustion with an Artificial Neural Network Linked to a Fluid Mechanics Code.  

National Technical Information Service (NTIS)

We have developed an artificial neural network (ANN) based combustion model and have integrated it into a fluid mechanics code (KIVA3V) to produce a new analysis tool (titled KIVA3V-ANN) that can yield accurate HCCI predictions at very low computational c...

A. Babaimopoulos D. L. Flowers J. Y. Chen S. M. Aceves

2006-01-01

305

Physical and numerical modeling of the external fluid mechanics of OTEC pilot plants  

Microsoft Academic Search

This study examined the near field external fluid mechanics of symmetrical OTEC pilot plant designs (20 to 80 MWe) under realistic deep water conditions. The objective was to assess the environmental impact of different plant configurations and to determine if pilot plants can be expected to operate without degrading the thermal resource available for power production. Physical modeling studies were

P. N. Singarella; E. E. Adams

1982-01-01

306

Analysis of the Transient Behavior of Rotary Lip Seals-Fluid Mechanics and Bulk Deformation  

Microsoft Academic Search

A numerical model of the transient behavior of rotary lip seals has been developed. It includes a fluid mechanics analysis of the lubricating film, an elastic deformation analysis of the lip, and predicts the lip seal state at every instant of time during a transient in shaft speed. The lip seal state includes such quantities as the lubricating film thickness

Richard F. Salant

1998-01-01

307

The variational iteration method: An efficient scheme for handling fractional partial differential equations in fluid mechanics  

Microsoft Academic Search

Variational iteration method has been used to handle linear and nonlinear differential equations. The main property of the method lies in its flexibility and ability to solve nonlinear equations accurately and conveniently. In this work, a general framework of the variational iteration method is presented for analytical treatment of fractional partial differential equations in fluid mechanics. The fractional derivatives are

Zaid Odibat; Shaher Momani

2009-01-01

308

Neural Mechanisms of Interference Control Underlie the Relationship between Fluid Intelligence and Working Memory Span  

ERIC Educational Resources Information Center

Fluid intelligence (gF) and working memory (WM) span predict success in demanding cognitive situations. Recent studies show that much of the variance in gF and WM span is shared, suggesting common neural mechanisms. This study provides a direct investigation of the degree to which shared variance in gF and WM span can be explained by neural…

Burgess, Gregory C.; Gray, Jeremy R.; Conway, Andrew R. A.; Braver, Todd S.

2011-01-01

309

The fluid mechanics of the ureter from a lubrication theory point of view  

Microsoft Academic Search

The function of a healthy ureter is analyzed in terms of a fluid-mechanical model. To the extent that the Reynolds number is of the order of one, the fundamental equations are shown to reduce to those of the theory of lubrication. It is found that from the point of view of the pressure variation with time (the urometro- gram) the

P. S. Lykoudis; Rudolf Roos

1970-01-01

310

Professor T. C. Papanastasiou's contributions to rheology and computational fluid mechanics  

Microsoft Academic Search

Professor T. C. Papanastasiou's contributions to rheology and computational fluid mechanics are numerous and have a lasting effect. In the short span of a professional career of about 10 years, and in such diverse places as the University of Minnesota, the University of Michigan, and the Aristotle University of Thessaloniki, he developed and implemented new ideas in the fields of

Evan Mitsoulis

1996-01-01

311

Heat transfer enhancement in nano-fluids suspensions: Possible mechanisms and explanations  

Microsoft Academic Search

The spectacular heat transfer enhancement revealed experimentally in nano-fluids suspensions is being investigated theoretically at the macro-scale level aiming at explaining the possible mechanisms that lead to such impressive experimental results. In particular, the possibility that thermal wave effects via hyperbolic heat conduction could have been the source of the excessively improved effective thermal conductivity of the suspension is shown

Johnathan J. Vadasz; Saneshan Govender; Peter Vadasz

2005-01-01

312

A fully coupled thermal-mechanical-fluid flow model for nonlinear geologic systems  

Microsoft Academic Search

A single model is presented which describes fully coupled thermal-mechanical-fluid flow behavior of highly nonlinear, dynamic or quasistatic, porous geologic systems. The mathematical formulation for the model utilizes the continuum theory of mixtures to describe the multiphase nature of the system, and incremental linear constitutive theory to describe the path dependency of nonlinear material behavior. The model, incorporated in an

R. D. Hart

1981-01-01

313

Neural Mechanisms of Interference Control Underlie the Relationship between Fluid Intelligence and Working Memory Span  

ERIC Educational Resources Information Center

|Fluid intelligence (gF) and working memory (WM) span predict success in demanding cognitive situations. Recent studies show that much of the variance in gF and WM span is shared, suggesting common neural mechanisms. This study provides a direct investigation of the degree to which shared variance in gF and WM span can be explained by neural…

Burgess, Gregory C.; Gray, Jeremy R.; Conway, Andrew R. A.; Braver, Todd S.

2011-01-01

314

Notes on the KIVA-II software and chemically reactive fluid mechanics.  

National Technical Information Service (NTIS)

This report represents a set of working notes regarding the mechanics of chemically reactive fluids with sprays, and their numerical simulation with the KIVA-II software. KIVA-II is a large FORTRAN program developed at Los Alamos National Laboratory for i...

M. J. Holst

1992-01-01

315

Proceedings of the 31st heat transfer and fluid mechanics institute  

Microsoft Academic Search

This book contains the proceedings of a conference on heat transfer and fluid mechanics. Topics covered include: general approach to one-dimensional internal gas dynamics; enhanced nucleate boiling heat transfer using a cylindrical attachment; unified porous media modeling; and an in-situ technique for rock thermophysical property measurement and site characterization.

F. H. Reardon; D. Thinh

1989-01-01

316

A Computational Fluid Dynamics (CFD) analysis of an undulatory mechanical fin driven by shape memory alloy  

Microsoft Academic Search

Many fishes use undulatory fin to propel themselves in the underwater environment. These locomotor mechanisms have a popular\\u000a interest to many researchers. In the present study, we perform a three-dimensional unsteady computation of an undulatory mechanical\\u000a fin that is driven by Shape Memory Alloy (SMA). The objective of the computation is to investigate the fluid dynamics of force\\u000a production associated

Yong-Hua Zhang; Jian-Hui He; Jie Yang; Shi-Wu Zhang; Kin Huat Low

2006-01-01

317

A hybrid semiempirical quantum mechanical and lattice-sum method for electrostatic interactions in fluid simulations  

Microsoft Academic Search

A method is described to incorporate the Ewald lattice-sum method into quantum mechanical calculations in hybrid quantum and molecular mechanical (QM\\/MM) fluid simulations. The procedure is illustrated through standard free energy perturbation calculations in the context of Monte Carlo simulations. The free energy of hydration of chloride ion was computed using the hybrid QM\\/MM-Ewald method, and comparison was made to

Jiali Gao; Cristobal Alhambra

1997-01-01

318

Overview of heat transfer and fluid flow problem areas encountered in stirling engine modeling  

SciTech Connect

NASA Lewis Research Center has been managing Stirling engine development programs for over a decade. In addition to contractual programs, this work has included in-house engine testing and development of engine computer models. Attempts to validate Stirling engine computer models with test data have demonstrated that engine thermodynamic losses need better characterization. Various Stirling engine thermodynamic losses and efforts that are underway to characterize these losses are discussed.

Tew, R.C. Jr.

1988-02-01

319

Mechanical Engineering of the Linac for the Spallation Neutron Source  

SciTech Connect

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.

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

320

Surveying Students and Alumni for Evaluation of a B.S. Program in Mechanical Engineering  

Microsoft Academic Search

This paper describes a survey of graduating seniors and alumni from the Mechanical Engineering Bachelor of Science Program at the State University of New York at Buffalo. The survey has been developed to guide the direction and continuous improvement of our mechanical engineering program. It attempts to identify the perceived needs of our student customers by asking them to rate

R. W. Mayne; A. K. Patra; R. C. Wetherhold; K. E. Lewis; W. J. Rae

321

Effect of fluid circulation on subduction interface tectonic processes: Insights from thermo-mechanical numerical modelling  

NASA Astrophysics Data System (ADS)

Both geophysical and petrological data suggest that large amounts of water are released in subduction zones during the burial of oceanic lithosphere through metamorphic dehydration reactions. These fluids are generally considered to be responsible for mantle wedge hydration, mechanical weakening of the plate interface and to affect slab-interface seismicity. In order to bridge the gap between subduction dynamics and the wealth of field, petrological and experimental data documenting small-scale fluid circulation at mantle depths, we designed a bi-phase model, in which fluid migration is driven by rock fluid concentrations, non-lithostatic pressure gradients and deformation. Oceanic subduction is modelled using a forward visco-elasto-plastic thermo-mechanically and thermodynamically coupled code (FLAMAR) following the previous work by Yamato et al. (2007). After 16.5 Myr of convergence, deformation is accommodated along the subduction interface by a low-strength shear zone characterised by a weak (10-25% of serpentinite) and relatively narrow (5-10 km) serpentinized front in the reference experiment. Dehydration associated with eclogitization of the oceanic crust (60-75 km depth) and serpentinite breakdown (110-130 km depth) significantly decreases the mechanical strength of the mantle at these depths, thereby favouring the detachment of large slices of oceanic crust along the plate interface. The geometries obtained are in good agreement with reconstructions derived from field evidence from the Alpine eclogite-facies ophiolitic belt (i.e., coherent fragments of oceanic crust detached at ca.80 km depth in the Alpine subduction zone and exhumed along the subduction interface). Through a parametric study, we further investigate the role of various parameters, such as fluid circulation, oceanic crustal structure and rheology, on the formation of such large tectonic slices. We conclude that the detachment of oceanic crust slices is largely promoted by fluid circulation along the subduction interface and by the subduction of a strong and originally discontinuous mafic crust.

Angiboust, S.; Wolf, S.; Burov, E.; Agard, P.; Yamato, P.

2012-12-01

322

An integrated muscle mechanic-fluid dynamic model of lamprey swimming  

NASA Astrophysics Data System (ADS)

In an effort towards a detailed understanding of the generation and control of vertebrate locomotion, including the role of the CPG and its interactions with reflexive feedback, muscle mechanics, and external fluid dynamics, we study a simple vertebrate, the lamprey. Lamprey body undulations are a result of a wave of neural activation that passes from head to tail, causing a wave of muscle activation. These active forces are mediated by passive structural forces. We present recent results from a model that fully couples a viscous, incompressible fluid with nonlinear muscle mechanics. We measure the dependence of the phase lag between activation wave and mechanical wave as a function of model parameters, such as body stiffness and muscle strength. Simulation results are compared to experiments utilizing both real and synthetic lamprey.

Hsu, Chia-Yu; Tytell, Eric; Fauci, Lisa

2009-11-01

323

Analysis of Coupled Multiphase Fluid Flow, Heat Transfer and Mechanical Deformation at the Yucca Mountain Drift Scale Test.  

National Technical Information Service (NTIS)

A numerical simulation of coupled multiphase fluid flow, heat transfer, and mechanical deformation was carried out to study coupled thermal-hydrological-mechanical (THM) processes at the Yucca Mountain Drift Scale Test (DST) and for validation of a couple...

J. Rutqvist C. F. Tsang Y. Tsang

2005-01-01

324

Ionization in diesel combustion: Mechanism, new instrumentation and engine applications  

Microsoft Academic Search

Diesel engines are known for their superior fuel economy and high power density. However they emit undesirable high levels of nitrogen oxide (NOx) and black particulate smoke (Soot). To reduce these emissions, close loop engine control strategies are required. Therefore, there is a need for an in-cylinder combustion sensor. The ion current sensor has been used for combustion sensing in

Fadi Estefanous

2011-01-01

325

Ionization in diesel combustion: Mechanism, new instrumentation and engine applications  

Microsoft Academic Search

Diesel engines are known for their superior fuel economy and high power density. However they emit undesirable high levels of nitrogen oxide (NO x) and black particulate smoke (Soot). To reduce these emissions, close loop engine control strategies are required. Therefore, there is a need for an in-cylinder combustion sensor. The ion current sensor has been used for combustion sensing

Fadi A Estefanous

2011-01-01

326

Continuum Mechanics in a Restructured Engineering Undergraduate Curriculum  

Microsoft Academic Search

The framework of the revised undergraduate engineering curriculum at Texas A&M University consists of the basic conservation principles and their application to engineering science. The conservation principles are presented in a way consistent with the Kolb learning cycle and an active approach to teaching. Utilizing these principles, a unified pedagogical process is developed, which can be applied to cover topics

D. C. LAGOUDAS; J. D. WHITCOMB; D. A. MILLER; M. Z. LAGOUDAS; K. J. SHRYOCK

327

Electrorheological fluids  

SciTech Connect

An electrorheological fluid is a substance whose form changes in the presence of electric fields. Depending on the strength of the field to which it is subjected, an electrorheological fluid can run freely like water, ooze like honey or solidify like gelatin. Indeed, the substance can switch from ne state to another within a few milliseconds. Electrorheological fluids are easy to make; they consist of microscopic particles suspended in an insulating liquid. Yet they are not ready for most commercial applications. They tend to suffer from a number of problems, including structural weakness as solids, abrasiveness as liquids and chemical breakdown, especially at high temperatures. Automotive engineers could imagine, for instance, constructing an electrorheological clutch. It was also hoped that electrorheological fluids would lead to valveless hydraulic systems, in which solidifying fluid would shut off flow through a thin section of pipe. Electrorheological fluids also offer the possibility of a shock absorber that provides response times of milliseconds and does not require mechanical adjustments. 3 refs.

Halsey, T.C. [Univ. of Chicago, IL (United States); Martin, J.E. [Sandia National Lab., Albuquerque, NM (United States)

1993-10-01

328

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

PubMed Central

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.

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

329

Thermodynamic analysis of a ? type Stirling engine with a displacer driving mechanism by means of a lever  

Microsoft Academic Search

In this study a novel configuration of ? type Stirling engine was described and studied from kinematic and thermodynamics points of view. Some aspects of the novel engine were compared to the crank driven and Rhombic-drive engines. By means of nodal analysis, the instantaneous temperature distribution of working fluid, through the heating–cooling passage, conducting the cold space to hot space,

Halit Karabulut; Fatih Aksoy; Erkan Öztürk

2009-01-01

330

Mechanisms of self-cleaning in fluid-based smooth adhesive pads of insects.  

PubMed

Pressure-sensitive adhesives such as tapes become easily contaminated by dust particles. By contrast, animal adhesive pads are able to self-clean and can be reused millions of times over a lifetime with little reduction in adhesion. However, the detailed mechanisms underlying this ability are still unclear. Here we test in adhesive pads of stick insects (Carausius morosus) (1) whether self-cleaning is enhanced by the liquid pad secretion, and (2) whether alternating push-pull movements aid the removal of particles. We measured attachment forces of insect pads on glass after contamination with 10 µm polystyrene beads. While the amount of fluid present on the pad showed no effect on the pads' susceptibility to contamination, the recovery of adhesive forces after contamination was faster when higher fluid levels were present. However, this effect does not appear to be based on a faster rate of self-cleaning since the number of spheres deposited with each step did not increase with fluid level. Instead, the fluid may aid the recovery of adhesive forces by filling in the gaps between contaminating particles, similar to the fluid's function on rough surfaces. Further, we found no evidence that an alternation of pushing and pulling movements, as found in natural steps, leads to a more efficient recovery of adhesion than repeated pulling slides. PMID:22750667

Clemente, Christofer J; Federle, Walter

2012-07-03

331

Development of fluid overpressures in crustal faults and implications for earthquakes mechanics  

NASA Astrophysics Data System (ADS)

The development and maintenance of fluid overpressures strongly influence the mechanical behavior of the crust and especially crustal fault zones. The mechanisms allowing fluid pressure build-up are still open questions, and their influence on tectonic and fault weakening processes remain unclear. The determination of the hydraulic and mechanical properties of crustal fault zone elements is a key aspect to improve our understanding of the fluid-tectonic interactions and more particularly the role of fluids in fault mechanics and earthquake triggering. Here we address this question combining geological observations, laboratory experiments and hydromechanical models of an active crustal fault-zone in the Ubaye-Argentera area (southeastern France). Previous studies showed that the fluids located in the fault zone developed overpressures between 7 and 26 MPa, that triggered intense seismic swarms (i.e. 16,000 events in 2003-2004) (Jenatton et al., 2007; Daniel et al., 2011; Leclère et al., 2012). The fault-zone studied here is located in the Argentera external crystalline massif and is connected to regional NW-SE steeply-dipping dextral strike-slip faults with an offset of several kilometers. The fault zone cuts through migmatitic gneisses composed of quartz, K-feldspar, plagioclase, biotite and minor muscovite. It exposes several anastomosed core zones surrounded by damage zones with a pluri-decametric total width. The core zones are made up of centimetric to pluridecimetric phyllosilicate-rich gouge layers while the damage zones are composed of pluri-metric phyllonitic rock derived from mylonite. The permeability and elastic moduli of the host rock, damage zone and fault core were measured from plugs with a diameter of 20 mm and lengths between 26 to 51 mm, using a high-pressure hydrostatic fluid-flow apparatus. Measurements were made with confining pressures ranging from 30 to 210 MPa and using argon pore fluid pressure of 20 MPa. Data show a variation of the permeability values of one order of magnitude between host rock and fault zone and a decrease of 50% of the elastic properties between host rock and core zone. The heterogeneity of properties is related to the development of different microstructures across the fault-zone during the tectonic history. From these physical property values and the fault zone architecture, we analyze the effects of sudden mechanical loading on the development of fluid overpressures in fault-zone. To do this, we use a series of 1-D hydromechanical numerical models to show that sudden mechanical stress increase is a viable mechanism for fluid overpressuring in fault-zone with spatially-varying elastic and hydraulic properties. Based on these results, we discuss the implications for earthquake triggering.on crustal-scale faults.

Leclère, Henri; Cappa, Frédéric; Faulkner, Daniel; Armitage, Peter; Blake, Oshaine; Fabbri, Olivier

2013-04-01

332

Integrating Materials Science into the Mechanical Engineering Curriculum  

Microsoft Academic Search

Much of the challenge in introducing Materials Science concepts into the engineering curriculum arises because this is the first time many students are tested on their conceptual understanding rather than just the ability to \\

Judy Schneider

2006-01-01

333

Stereo photography of neutral density He-filled bubbles for 3-D fluid motion studies in an engine cylinder.  

PubMed

A new technique has been developed for studies of fluid motion within the cylinder of a reciprocating piston engine during the air induction process. Helium-filled bubbles, serving as neutrally buoyant flow tracer particles, enter the cylinder along with the inducted air charge. The bubble motion is recorded by stereo cine photography through the transparent cylinder of a specially designed research engine. Quantitative data on the 3-D velocity field generated during induction is obtained from frame-to-frame analysis of the stereo images, taking into account refraction of the rays due to the transparent cylinder. Other applications for which this technique appears suitable include measurements of velocity fields within intake ports and flow-field dynamics within intake manifolds of multicylinder engines. PMID:20372559

Kent, J C; Eaton, A R

1982-03-01

334

Mechanical and Flow Excited Vibrations of Elastic Plates and Cylindrical Shells in Dense Fluids.  

NASA Astrophysics Data System (ADS)

Mechanical and flow excited vibrations of elastic plates and cylindrical shells in dense fluids are presented. The perturbation method is used to connect the basic equations in fluid mechanics and acoustics. A computer model based on a boundary-fitted coordinate transformation is used to solve the two-dimensional incompressible viscous time dependent fluid flow problem. Numerical results for flow over vibrating plates and flow across vibrating cylindrical shells are presented. Several fluid-acoustic-solid interaction problems are addressed in the thesis using a generic block diagram model. These problems include both viscous and inviscid flows over elastic plates and shells. The emphasis in the study has been to determine the near field surface pressure distribution on the elastic vibrators. The surface pressure for the forced vibration of elastic plates in contact with inviscid fluid flow is predicted using time and wavenumber domain approaches. A Mach number dependent modal impulse response representation is also developed. Numerical evaluation shows significant changes in the surface pressure as a function of the Mach number, vibration frequency and mode shapes. The surface pressure on an elastic plate for the coupled fluid-plate problem has been addressed through analytical and numerical approaches. As a result of fluid loading, a set of coupled convolution integral equations is developed by using a modal expansion technique. These equations are solved by the marching forward in time technique. Numerical results for flow over a vibrating plate are also presented. The surface pressure on a cylindrical shell with a specified radial excitation without flow is addressed by a modal expansion technique. A time domain approach to determine the transient displacement and pressure fields of fluid loaded infinitely long cylindrical shell, which are excited by broadband excitations is presented. Numerical results are also presented to illustrate typical characteristics of the displacement field for specified excitations. Finally a coupled hydrodynamic and cylindrical shell numerical model is utilized to evaluate the surface pressure response of a cylindrical shell in contact with a viscous flow across the cylinder. Numerical results are presented to illustrate the nature of the characteristics of the flow field and the shell displacements.

Li, Dong-Jye

335

PREFACE: 40th anniversary of the Japan Society of Fluid Mechanics 40th anniversary of the Japan Society of Fluid Mechanics  

NASA Astrophysics Data System (ADS)

The Japan Society of Fluid Mechanics (JSFM) turned 40 years old in 2008. To celebrate the 40th anniversary, JSFM organized a one-day conference on 5 September 2008 at Kobe University Centennial Hall. The conference was composed of seven invited lectures: three of them were given by distinguished foreign researchers and four were given by relatively young but internationally active Japanese researchers. At the same time, JSFM planned to dedicate an issue of Fluid Dynamics Research (FDR) to the conference. This special issue, which contains six articles based on the lectures at the conference, is the fruition of the plan. The promising program of the conference and the fact that the second day of the Annual Meeting of JSFM was dedicated to this conference attracted a large audience (215 participants). The conference was indeed very successful, thanks to the outstanding lectures and active participation of the audience. I am sure that the articles in this special section, which cover several important areas in modern fluid dynamics, will also interest the readers of FDR. In particular, it will be a great pleasure to me if young researchers are stimulated and motivated by the articles. As the chair of the one-day conference, I would like to express my thanks to Prof. N D Katopodes, Prof. G J F van Heijst, Prof. S Zaleski, Prof. G Kawahara, Prof. S Takagi and Prof. Y Tsuji for their contributions to this special section. Taking this opportunity, I would also like to thank Prof. S Kida (President of JSFM in 2008), Prof. M Funakoshi (Editor-in-Chief of FDR) and the members of the organizing committee of the conference for their continued support and cooperation.

Aoki, Kazuo

2009-12-01

336

Mechanical Responses to Metamorphic Fluid-Rock Reactions - Natural Examples of Weakening vs. Embrittlement  

NASA Astrophysics Data System (ADS)

Metamorphic reactions can influence strain accommodation mechanisms by changing grain size and by releasing, consuming, or changing the composition of an equilibrium fluid phase. Different deformation mechanisms, in turn, can affect metamorphic reaction rates and approaches to equilibrium by changing grain size, dislocation density, the arrangement of mineral grain boundaries, and local bulk composition. Our general understanding of water weakening effects in silicate minerals might lead us to predict that dehydration reactions will contribute to enhanced crystal plasticity, and that water-consuming reactions will strengthen rocks. Natural examples of interactions between fluid-rock reactions and strain accommodation in samples from the Tauern Window, eastern Alps, illustrate cases that both support and refute these predictions. (1) Finely interlayered graphitic and nongraphitic schists show different mechanisms of strain accommodation at different stages in their history. During burial, ductile strain was localized into graphitic horizons. During decompression, however, closely spaced Mode I extension cracks and carbonic fluid inclusion (FI) planes developed throughout the graphitic layers. Nongraphitic layers lack cracks, contain aqueous FIs, and maintained strain compatibility via crystal plasticity during unroofing. During decompression, reaction between graphite and aqueous pore fluid produced increasingly carbonic fluid that inhibited dislocation climb, experienced >60% volume expansion, and promoted Mode I crack formation. In these rocks, H2O- consuming reactions thus led to embrittlement at mid-crustal depths. (2) Finely banded mafic eclogites show outcrop- and microscopic scale evidence for synchronous strain accommodation via both crystal plasticity and brittle failure at 2 GPa. These rocks also record significant heterogeneities in reaction-controlled aH2O. Layers with aH2O>0.6 initially accommodated strain by pressure solution, producing complexly zoned grains with high aspect ratio. Continued deformation at high P caused elongate porphyroblasts to form extension fractures that propagated across the high aH2O layers. In contrast, layers with low aH2O accommodated strain via dislocation creep. High aH2O thus promoted brittle failure rather than water weakening in these rocks. Polymineralic rocks have the potential to produce fluids of different composition at different P-T conditions. These fluids can contribute to both weakening and strengthening of the rocks. We should thus expect complex feedback effects between metamorphism and deformation during orogenesis. These interactions may play a fundamental role in controlling rheology and patterns of seismicity in the deep crust and mantle.

Selverstone, J.

2006-12-01

337

Solving fractional partial differential equations in fluid mechanics by generalized differential transform method  

Microsoft Academic Search

In this paper, the generalized differential transform method is implemented for solving several linear fractional partial differential equations arising in fluid mechanics. This method is based on the two-dimensional differential transform method (DTM) and generalized Taylor's formula. Numerical illustrations of the time-fractional diffusion equation and the time-fractional wave equation are investigated to demonstrate the effectiveness of this method. Results obtained

Xuehui Chen; Liang Wei; Jizhe Sui; Xiaoliang Zhang; Liancun Zheng

2011-01-01

338

Fluid Mechanics of Distillation Trays (I): Depth-Averaged Theory and One-Dimensional Flows  

Microsoft Academic Search

Rigorous design of a distillation column requires a better fundamental understanding of the fluid mechanics of bubble formation and global flows on trays than that currently available. To progress beyond the empirical-or correlation-based state of understanding that currently exists, a theoretical and computational framework is described here that is based on reducing the governing set of three-dimensional conservation equations to

Fred K. Wohlhuter; Osman A. Basaran; George M. Harriott

1995-01-01

339

Development of a Walking Model for Teaching Material and Application to Mechanical Engineering Introductory Education  

NASA Astrophysics Data System (ADS)

Japan has many toys that use walking mechanisms with movement principles based on fundamental concepts of modern science and technology. One traditional toy is called the One-step Walking Toy (issokutobi-hoko) . Theories of science and technology have not explained this toy's movement. Theoretical analyses and experiments can clarify this movement. In this study, the effectiveness of this walking model as a teaching material is evaluated based on physics and mechanical engineering concepts. Evaluation results clarify that this model's learning contents are based on physics and mechanical engineering principles. Furthermore, this model was used for introductory mechanical engineering education. Results of the class practice demonstrate that this model is an effective introductory teaching material for mechanical engineering.

Nakazawa, Tsuyoshi; Mita, Sumiyoshi

340

Turbulent particle transport in streams: can exponential settling be reconciled with fluid mechanics?  

PubMed

Most ecological studies of particle transport in streams that focus on fine particulate organic matter or benthic invertebrates use the Exponential Settling Model (ESM) to characterize the longitudinal pattern of particle settling on the bed. The ESM predicts that if particles are released into a stream, the proportion that have not yet settled will decline exponentially with transport time or distance and will be independent of the release elevation above the bed. To date, no credible basis in fluid mechanics has been established for this model, nor has it been rigorously tested against more-mechanistic alternative models. One alternative is the Local Exchange Model (LEM), which is a stochastic advection-diffusion model that includes both longitudinal and vertical spatial dimensions and is based on classical fluid mechanics. The LEM predicts that particle settling will be non-exponential in the near field but will become exponential in the far field, providing a new theoretical justification for far-field exponential settling that is based on plausible fluid mechanics. We review properties of the ESM and LEM and compare these with available empirical evidence. Most evidence supports the prediction of both models that settling will be exponential in the far field but contradicts the ESM's prediction that a single exponential distribution will hold for all transport times and distances. PMID:22281520

McNair, James N; Newbold, J Denis

2012-01-21

341

Computational modelling of the mechanics of trabecular bone and marrow using fluid structure interaction techniques.  

PubMed

Bone marrow found within the porous structure of trabecular bone provides a specialized environment for numerous cell types, including mesenchymal stem cells (MSCs). Studies have sought to characterize the mechanical environment imposed on MSCs, however, a particular challenge is that marrow displays the characteristics of a fluid, while surrounded by bone that is subject to deformation, and previous experimental and computational studies have been unable to fully capture the resulting complex mechanical environment. The objective of this study was to develop a fluid structure interaction (FSI) model of trabecular bone and marrow to predict the mechanical environment of MSCs in vivo and to examine how this environment changes during osteoporosis. An idealized repeating unit was used to compare FSI techniques to a computational fluid dynamics only approach. These techniques were used to determine the effect of lower bone mass and different marrow viscosities, representative of osteoporosis, on the shear stress generated within bone marrow. Results report that shear stresses generated within bone marrow under physiological loading conditions are within the range known to stimulate a mechanobiological response in MSCs in vitro. Additionally, lower bone mass leads to an increase in the shear stress generated within the marrow, while a decrease in bone marrow viscosity reduces this generated shear stress. PMID:23519534

Birmingham, E; Grogan, J A; Niebur, G L; McNamara, L M; McHugh, P E

2012-12-04

342

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

PubMed Central

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 (?) 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 ?mm 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, ?(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.

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

2009-01-01

343

Fluid motion within the cylinder of internal combustion engines - The 1986 Freeman Scholar Lecture  

NASA Astrophysics Data System (ADS)

Aspects of gas motion into, within, and out of the engine cylinder which govern the combustion characteristics and capabilities of spark-ignition engines and compression-ignition or diesel engines are considered. Flow characteristics through inlet and exhaust valves in four-stroke cycle engines, and through ports in the cylinder liner in two-stroke cycle engines, are discussed. Features and turbulence characteristics of common in-cylinder flows including the large scale rotating flows precipitated by the conical intake jet and two-stroke scavenger flows are reviewed. The flow phenomenon near walls are then discussed, with application to heat transfer and hydrocarbon emissions phenomena.

Heywood, John B.

1987-03-01

344

Intrinsically irreversible heat engine  

DOEpatents

A class of heat engines based on an intrinsically irreversible heat transfer process is disclosed. In a typical embodiment the engine comprises a compressible fluid that is cyclically compressed and expanded while at the same time being driven in reciprocal motion by a positive displacement drive means. A second thermodynamic medium is maintained in imperfect thermal contact with the fluid and bears a broken thermodynamic symmetry with respect to the fluid. The second thermodynamic medium is a structure adapted to have a low fluid flow impedance with respect to the compressible fluid, and which is further adapted to be in only moderate thermal contact with the fluid. In operation, thermal energy is pumped along the second medium due to a phase lag between the cyclical heating and cooling of the fluid and the resulting heat conduction between the fluid and the medium. In a preferred embodiment the engine comprises an acoustical drive and a housing containing a gas which is driven at a resonant frequency so as to be maintained in a standing wave. Operation of the engine at acoustic frequencies improves the power density and coefficient of performance. The second thermodynamic medium can be coupled to suitable heat exchangers to utilize the engine as a simple refrigeration device having no mechanical moving parts. Alternatively, the engine is reversible in function so as to be utilizable as a prime mover by coupling it to suitable sources and sinks of heat.

Wheatley, J.C.; Swift, G.W.; Migliori, A.

1984-01-01

345

Intrinsically irreversible heat engine  

DOEpatents

A class of heat engines based on an intrinsically irreversible heat transfer process is disclosed. In a typical embodiment the engine comprises a compressible fluid that is cyclically compressed and expanded while at the same time being driven in reciprocal motion by a positive displacement drive means. A second thermodynamic medium is maintained in imperfect thermal contact with the fluid and bears a broken thermodynamic symmetry with respect to the fluid. The second thermodynamic medium is a structure adapted to have a low fluid flow impedance with respect to the compressible fluid, and which is further adapted to be in only moderate thermal contact with the fluid. In operation, thermal energy is pumped along the second medium due to a phase lag between the cyclical heating and cooling of the fluid and the resulting heat conduction between the fluid and the medium. In a preferred embodiment the engine comprises an acoustical drive and a housing containing a gas which is driven at a resonant frequency so as to be maintained in a standing wave. Operation of the engine at acoustic frequencies improves the power density and coefficient of performance. The second thermodynamic medium can be coupled to suitable heat exchangers to utilize the engine as a simple refrigeration device having no mechanical moving parts. Alternatively, the engine is reversible in function so as to be utilizable as a prime mover by coupling it to suitable sources and sinks of heat. 11 figs.

Wheatley, J.C.; Swift, G.W.; Migliori, A.

1984-12-25

346

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

NASA Astrophysics Data System (ADS)

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-? 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.

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

2010-01-01

347

Thermal and Mechanical Design Aspects of the LIFE Engine  

SciTech Connect

The Laser Inertial confinement fusion - Fission Energy (LIFE) engine encompasses the components of a LIFE power plant responsible for converting the thermal energy of fusion and fission reactions into electricity. The design and integration of these components must satisfy a challenging set of requirements driven by nuclear, thermal, geometric, structural, and materials considerations. This paper details a self-consistent configuration for the LIFE engine along with the methods and technologies selected to meet these stringent requirements. Included is discussion of plant layout, coolant flow dynamics, fuel temperatures, expected structural stresses, power cycle efficiencies, and first wall survival threats. Further research and to understand and resolve outstanding issues is also outlined.

Abbott, R P; Gerhard, M A; Latkowski, J F; Kramer, K J; Morris, K R; Peterson, P F; Seifried, J E

2008-10-25

348

Numerical Simulation of Reactive Flow in Internal Combustion Engines.  

National Technical Information Service (NTIS)

Multidimensional numerical simulations of the reactive fluid flow in an internal combustion engine cylinder are useful in helping engine designers obtain insight into the physical mechanisms governing efficiency and pollutant formation. A comprehensive nu...

L. D. Cloutman J. K. Dukowicz J. D. Ramshaw

1980-01-01

349

Protective effects of plasma replacement fluids on erythrocytes exposed to mechanical stress.  

PubMed

Haemoglobin release from 40 suspensions of packed red blood cells in modified fluid gelatin, 4% albumin solution, 6% hydroxyethyl starch and normal saline was investigated in vitro during circulation with a roller pump from a heart-lung machine for 120 min at a flow rate of 2.5 l.min-1 at room temperature. The lowest haemoglobin release was obtained with erythrocytes in modified fluid gelatin, whereas free haemoglobin concentrations became progressively higher with albumin, hydroxyethyl starch and normal saline [median free haemoglobin (interquartile range) after 120 min circulation: gelatin 493 (360-601) mg.l-1, albumin 692 (590-1111) mg.l-1, hydroxyethyl starch 1121 (692-1518) mg.l-1, normal saline 1178 (881-1757) mg.l-1, p < 0.001]. Modified fluid gelatin appears to have potent erythrocyte protective properties similar to those of albumin. This effect could decrease mechanical haemolysis during extracorporeal circulation or cell saver autotransfusion if modified fluid gelatin is used as part of a priming solution or as an additive in wash solutions. PMID:11012493

Sümpelmann, R; Schürholz, T; Marx, G; Zander, R

2000-10-01

350

Experiential Learning Strategies in a Mechanical Engineering Senior Course  

Microsoft Academic Search

This article presents an approach to enhance active and collaborative learning spaces in engineering education. The proposed strategy is a result of reflective observation of the stated output competencies and past experience. As a consequence, the course program has been reoriented to achieve the intended outcomes, in a framework of methodological strategies. The proposed methodology is focused on a group-based

R. Pascual; R. Uribe

351

Proceedings of the seventh international conference on offshore mechanics and Arctic engineering  

SciTech Connect

The proceedings of a conference on offshore mechanics and artic engineering are presented. Topics include the following: motion prediciton of a single point moored tanker subjected to current, wind and waves.

Chung, J.S.; Chakrabarti, S.K.

1988-01-01

352

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.

353

Proceedings of the eighth international conference on offshore mechanics and Arctic engineering. 1989  

Microsoft Academic Search

This book contains the proceedings of the Eighth International Conference on Offshore Mechanics and Arctic Engineering. Topics covered include: CAD application in offshore structure fabrication; A force control system for robotic manipulators; and intersections for trimmed surface patches.

N. M. Patrikalakis; J. S. Chung; M. J. Morgan

1989-01-01

354

Proceedings of the seventh international conference on offshore mechanics and Arctic engineering  

SciTech Connect

These proceedings collect papers given at a conference on offshore engineering. Topics include: fracture mechanics, vibration testing, wave energy converters, ocean thermal energy converters, underwater pipelines, offshore platforms, and design and installation of permanent mooring systems for tankers.

Chung, J.S.; Sparks, C.P.; Brekke, J.N.; Clukey, E.C.; Penney, T.R.

1988-01-01

355

Laser Doppler velocimetry measurements of flow within the cylinder of a motored tow-stroke cycle engine-comparison with some computational fluid dynamics predictions  

Microsoft Academic Search

This study was carried out to assess the ability of a computational fluid dynamics (CFD) code to predict the scavenging flow in the cylinder of a two-stroke cycle engine. Predictions were obtained from a CFD simulation of the flow within the cylinder. Due to the apparent sym-metry of the engine port layout, only half of the cylinder volume was modelled.

J. P. Creaven; R Fleck; R. G. Kenny; G Cunningham

2003-01-01

356

Fluids in brittle faulting - what do earthquake source mechanisms tell us?  

NASA Astrophysics Data System (ADS)

The occurrence of crack opening became a focus of many recent seismological studies. While the crack opens, a tensional normal stress acts on the fault plane. Thus, the slip vector during the earthquake deviates from the fault surface. In terms of the seismological terminology, this is reported as the non-double-couple component. The crack opening is possible in extensional stress state only, which is characterized by a negative normal stress acting on the fault plane. Because negative stresses in large depths are improbable, the tensile components of earthquakes are usually explained by a high fluid pressure in the fault zone. However, despite frequent fluid involvement in source processes, only few source mechanisms studies show doubtless non-DC components of the moment tensors. This holds also for the microseismicity accompanying the hydraulic fracture stimulation of hydrocarbon and geothermal reservoirs. We join the typical seismological and geomechanical approaches in order to improve our understanding of the presence of crack opening in natural and injection induced earthquakes. We explain the relation of the shear and normal tractions on the fault plane to the occurrence of tensile events and show the reason for seldom occurrence of crack opening. Further we propose a method for assessing the fluid involvement in the fracture process using the focal mechanisms and apply it to a suitable data set of injection-induced seismicity.

Fischer, Tomáå.¡; Guest, Alice

2010-05-01

357

Fluid Structural Analysis of Human Cerebral Aneurysm Using Their Own Wall Mechanical Properties  

PubMed Central

Computational Structural Dynamics (CSD) simulations, Computational Fluid Dynamics (CFD) simulation, and Fluid Structure Interaction (FSI) simulations were carried out in an anatomically realistic model of a saccular cerebral aneurysm with the objective of quantifying the effects of type of simulation on principal fluid and solid mechanics results. Eight CSD simulations, one CFD simulation, and four FSI simulations were made. The results allowed the study of the influence of the type of material elements in the solid, the aneurism's wall thickness, and the type of simulation on the modeling of a human cerebral aneurysm. The simulations use their own wall mechanical properties of the aneurysm. The more complex simulation was the FSI simulation completely coupled with hyperelastic Mooney-Rivlin material, normal internal pressure, and normal variable thickness. The FSI simulation coupled in one direction using hyperelastic Mooney-Rivlin material, normal internal pressure, and normal variable thickness is the one that presents the most similar results with respect to the more complex FSI simulation, requiring one-fourth of the calculation time.

Valencia, Alvaro; Burdiles, Patricio; Ignat, Miguel; Mura, Jorge; Rivera, Rodrigo; Sordo, Juan

2013-01-01

358

Freshman Education Program Made Up of Lecture, Experiment and Practice for Mechanical Engineering Students  

NASA Astrophysics Data System (ADS)

A new curriculum, which instills an appreciation in mechanical engineering and motivates freshman students to pursue this discipline in a college of technology, is presented. The curriculum is composed of lecture, experiment and practice to foster self-education ability. Numerous new and unique teaching processes were developed to meet our objectives and were evaluated through anonymous student evaluations. Nearly all students, who participated in this curriculum, showed increased interest in pursuing mechanical engineering.

Izawa, Satoru; Tanaka, Kohichi; Kawamura, Takashi

359

CAEMEMS: an integrated computer-aided engineering workbench for micro-electro-mechanical systems  

Microsoft Academic Search

A summary of a proposed computer-aided engineering system for micro-electro-mechanical systems is presented. The system will take advantage of existing high-level integrated mechanical engineering software tools and add application-specific software for the system to function as a MEMS-specific designers' workbench environment. The system, called CAEMEMS, will include database structures (MEMS Databases); a process modeler that can model MEMS-relevant process sequences

S. Crary; Y. Zhang

1990-01-01

360

MFGA-IDT2 workshop: Astrophysical and geophysical fluid mechanics: the impact of data on turbulence theories  

Microsoft Academic Search

1 Facts about the Workshop This workshop was convened on November 13-15 1995 by E. Falgarone and D. Schertzer within the framework of the Groupe de Recherche Mecanique des Fluides Geophysiques et Astrophysiques (GdR MFGA, Research Group of Geophysical and Astrophysical Fluid Mechanics) of Centre National de la Recherche Scientifique (CNRS, (French) National Center for Scientific Research). This Research Group

D. Schertzer; E. Falgarone

1996-01-01

361

A FLUID MECHANICAL APPROACH TO TURBULENT MIXING AND CHEMICAL REACTION PART II MICROMIXING IN THE LIGHT OF TURBULENCE THEORY  

Microsoft Academic Search

The objectives are to identify the key physical processes contributing to mixing on the molecular scale, using information from Fluid Mechanics, and to construct a corresponding mathematical model. The concentration spectrum indicates that molecular diffusion and hence micromixing starts towards the fine scale end of the viscous-convective subrange and becomes dominant in the viscous-diffusive subrange. Such small fluid elements are

J. BALDYGA; J. R. BOURNE

1984-01-01

362

A study of the composition of pericardial fluid, with special reference to the probable mechanism of fluid formation.  

PubMed Central

The composition of pericardial fluid and simultaneously withdrawn plasma have been measured in rabbits and greyhounds. 1. Sodium and chloride distributions were found to be not markedly different from the ratio predicted for a passive distribution. The small deviation found in greyhounds could be largely corrected by the in vitro dialysis of plasma against pericardial fluid. 2. Calcium and magnesium were distributed in a manner expected from a passive ultrafiltrate of plasma. 3. Pericardial fluid was found to contain between one quarter and one third of the protein of plasma. 4. Separation of the protein constituents demonstrated a far higher proportion of albumin to other proteins in the pericardial fluid. 5. The osmolality of plasma was slightly higher than that of pericardial fluid, as would be expected from a plasma ultrafiltrate. 6. The potassium concentration of pericardial fluid was higher than the plasma concentration in all animals studied. This difference could be abolished, and an expected distribution obtained in the samples from greyhounds, by the in vitro dialysis of plasma against pericardial fluid. This observation for potassium cannot be attributed to haemolysis of blood in pericardial fluid samples or to the use of any inappropriate references. It is suggested that the elevated potassium concentration of pericardial fluid may reflect the lability of the cardiac intracellular potassium during cardiac contraction. 7. The results obtained in this study do not support the concept of an active secretion of pericardial fluid as has been claimed by others. The distribution of ions would appear to be passive and to follow the values predicted by the Gibbs-Donnan relationship.

Gibson, A T; Segal, M B

1978-01-01

363

Multidimensional Proteomics Analysis of Amniotic Fluid to Provide Insight into the Mechanisms of Idiopathic Preterm Birth  

PubMed Central

Background Though recent advancement in proteomics has provided a novel perspective on several distinct pathogenetic mechanisms leading to preterm birth (inflammation, bleeding), the etiology of most preterm births still remains elusive. We conducted a multidimensional proteomic analysis of the amniotic fluid to identify pathways related to preterm birth in the absence of inflammation or bleeding. Methodology/Principal Findings A proteomic fingerprint was generated from fresh amniotic fluid using surface-enhanced laser desorbtion ionization time of flight (SELDI-TOF) mass spectrometry in a total of 286 consecutive samples retrieved from women who presented with signs or symptoms of preterm labor or preterm premature rupture of the membranes. Inflammation and/or bleeding proteomic patterns were detected in 32% (92/286) of the SELDI tracings. In the remaining tracings, a hierarchical algorithm was applied based on descriptors quantifying similarity/dissimilarity among proteomic fingerprints. This allowed identification of a novel profile (Q-profile) based on the presence of 5 SELDI peaks in the 10–12.5 kDa mass area. Women displaying the Q-profile (mean±SD, gestational age: 25±4 weeks, n?=?40) were more likely to deliver preterm despite expectant management in the context of intact membranes and normal amniotic fluid clinical results. Utilizing identification-centered proteomics techniques (fluorescence two-dimensional differential gel electrophoresis, robotic tryptic digestion and mass spectrometry) coupled with Protein ANalysis THrough Evolutionary Relationships (PANTHER) ontological classifications, we determined that in amniotic fluids with Q-profile the differentially expressed proteins are primarily involved in non-inflammatory biological processes such as protein metabolism, signal transduction and transport. Conclusion/Significance Proteomic profiling of amniotic fluid coupled with non-hierarchical bioinformatics algorithms identified a subgroup of patients at risk for preterm birth in the absence of intra-amniotic inflammation or bleeding, suggesting a novel pathogenetic pathway leading to preterm birth. The altered proteins may offer opportunities for therapeutical intervention and future drug development to prevent prematurity.

Buhimschi, Irina A.; Zhao, Guomao; Rosenberg, Victor A.; Abdel-Razeq, Sonya; Thung, Stephen; Buhimschi, Catalin S.

2008-01-01

364

TOPICAL REVIEW: Overview of the lattice Boltzmann method for nano- and microscale fluid dynamics in materials science and engineering  

NASA Astrophysics Data System (ADS)

The article gives an overview of the lattice Boltzmann method as a powerful technique for the simulation of single and multi-phase flows in complex geometries. Owing to its excellent numerical stability and constitutive versatility it can play an essential role as a simulation tool for understanding advanced materials and processes. Unlike conventional Navier-Stokes solvers, lattice Boltzmann methods consider flows to be composed of a collection of pseudo-particles that are represented by a velocity distribution function. These fluid portions reside and interact on the nodes of a grid. System dynamics and complexity emerge by the repeated application of local rules for the motion, collision and redistribution of these coarse-grained droplets. The lattice Boltzmann method, therefore, is an ideal approach for mesoscale and scale-bridging simulations. It is capable to tackling particularly those problems which are ubiquitous characteristics of flows in the world of materials science and engineering, namely, flows under complicated geometrical boundary conditions, multi-scale flow phenomena, phase transformation in flows, complex solid-liquid interfaces, surface reactions in fluids, liquid-solid flows of colloidal suspensions and turbulence. Since the basic structure of the method is that of a synchronous automaton it is also an ideal platform for realizing combinations with related simulation techniques such as cellular automata or Potts models for crystal growth in a fluid or gas environment. This overview consists of two parts. The first one reviews the philosophy and the formal concepts behind the lattice Boltzmann approach and presents also related pseudo-particle approaches. The second one gives concrete examples in the area of computational materials science and process engineering, such as the prediction of lubrication dynamics in metal forming, dendritic crystal growth under the influence of fluid convection, simulation of metal foam processing, flow percolation in confined geometries, liquid crystal hydrodynamics and processing of polymer blends.

Raabe, D.

2004-11-01

365

WAVE IMPLOSION AS AN INITIATION MECHANISM FOR PULSE DETONATION ENGINES  

Microsoft Academic Search

A device has been developed which uses shock focusing to enhance the transmission e-ciency of an initiator tube when used with pulse detonation engines. The initiator is capable of initiating detonations in ethylene-air and propane-air mixtures using less initiator fuel than is used in a conventional initiator tube. This toroidal initiator uses a single spark and an array of small-diameter

S. I. Jackson; M. P. Grunthaner; J. E. Shepherd

366

Attack or attacked: the sensory and fluid mechanical constraints of copepods' predator-prey interactions.  

PubMed

Many animals are predator and prey at the same time. This dual position represents a fundamental dilemma because gathering food often leads to increased exposure to predators. The optimization of the tradeoff between eating and not being eaten depends strongly on the sensing, feeding, and mechanisms for mobility of the parties involved. Here, I describe the mechanisms of sensing, escaping predators, and capturing prey in marine pelagic copepods. I demonstrate that feeding tradeoffs vary with feeding mode, and I describe simple fluid mechanical models that are used to quantify these tradeoffs and review observations and experiments that support the assumptions and test the predictions. I conclude by presenting a mechanistically underpinned model that predicts optimal foraging behaviors and the resulting size-scaling and magnitude of copepods' clearance rates. PMID:23613321

Kiørboe, Thomas

2013-04-23

367

The fluid mechanics of a high aspect ratio slot with an impressed pressure gradient and secondary injection  

Microsoft Academic Search

A high aspect ratio slot flow (which emulates the gas leakage path in a gas turbine engine outer turbine air seal) is studied by use of a high aspect ratio slot using water as the working fluid. The cross section of the geometry is similar to a 'T', the slot being the vertical stroke and the main flow being the

John Bertram Sobanik

1993-01-01

368

Ocean crustal fault rocks and the chemo-mechanical record of hydrothermal fluid flow  

NASA Astrophysics Data System (ADS)

Hydrothermal systems in the oceanic crust appear to require fluid-flow conduits such as faults and fracture-networks. Laboratory and borehole experiments reinforce the need for fracturing to increase the otherwise intrinsically low basalt permeability to allow high-flux fluid flow. Additionally, microseismicity and surface displacements along mid-ocean ridges have been modeled as resulting from fluid flow along localized conduits during fluid-pressure modulated faulting events. Near-bottom images and samples of fault zones from in situ, basaltic East-Pacific Rise (EPR)-spread oceanic crust provide an opportunity to further establish linkages between faulting, fracturing, and hydrothermal fluid flow. Human Occupied Vehicle (HOV) Alvin investigations along the north wall of the Hess Deep rift found faults in lavas and dikes that display a core-damage zone structure. The damage zones can be quite extensive, with intensely fractured materials spanning tens-of-meters. In places the damage zones can be linked to the volcanic constructional history of the axial region, with undeformed dikes cross-cutting damaged materials and relatively undamaged lavas overlying more damaged ones. Faults are less-than meter-wide planar structures that in many instances accommodated relative rotations and displacements of dikes and lavas. Though fault displacements cannot be quantitatively determined, they are a maximum of 100-m based on local depth-variations in the base of the lavas, and this is probably an overestimate given variations in the depositional thickness of the lavas. Microstructurally, the damage-zone and fault-core materials exhibit increasing amounts of chlorite-filled fractures, culminating with a cataclastic (deformational) foliation comprising anomalously high concentrations of chlorite (and bulk-rock MgO). Remotely Operated Vehicle (ROV) Jason II and HOV Alvin work along the EPR-spread crust exposed in the Pito Deep rift found similar fault and damage zone structures. However, the Pito Deep rift also exposes distinctive quartz-rich hydrothermal breccias in the fault cores. As shown by isotopic, geochemical, and structural analyses, the fault breccias developed through multiple increments of fluid flow and faulting, likely at the base of axial black-smoker vents. Lastly, both Pito and Hess Deep rifts expose a distinctive fault gouge that is relatively unaltered. In the Pito Deep rift this unit can be clearly related to off-axis rift-related faulting, whereas in the Hess Deep rift certain gouge units are clearly part of the fault structure that developed predominantly in the axial region. Some of the fault-rock units therefore may have sealed faults to fluid flow whereas others, such as the chlorite-rich fracture systems, cataclasites, and quartz-rich breccias, were conduits. Given the well-understood spreading history of the EPR, and recent observations of axial deformation and hydrothermal fluid flow, these geological observations can be of great utility in placing bounds on the mechanical processes of faulting and fluid flow, particularly through ongoing quantitative microstructural analysis, rock-mechanics experiments, and comparisons with other spreading-rate environments.

Hayman, N. W.; Karson, J. A.

2010-12-01

369

Fatigue of orthodontic nickel–titanium (NiTi) wires in different fluids under constant mechanical stress  

Microsoft Academic Search

The aim of this study was to analyze in vitro the fatigue resistance of nickel–titanium (NiTi) and CuNiTi orthodontic wires when subjected to forces and fluids which are present intraorally. The wires were subjected to dynamic mechanical analysis (DMA) while they were immersed into different fluids with mechanical loading parameters similar to those that are subjected in the mouth. The

O. Prymak; A. Klocke; B. Kahl-Nieke; M. Epple

2004-01-01

370

Stigmatic fluid aids self-pollination in Roscoea debilis (Zingiberaceae): a new delayed selfing mechanism  

PubMed Central

Background and Aims Delayed selfing is the predominant mode of autonomous self-pollination in flowering plants. However, few delayed selfing mechanisms have been documented. This research aims to explore a new delayed selfing mechanism induced by stigmatic fluid in Roscoea debilis, a small perennial ginger. Methods Floral biology and flower visitors were surveyed. The capacity of autonomous selfing was evaluated by pollinator exclusion. The timing of autonomous sel?ng was estimated by emasculation at different flowering stages. The number of seeds produced from insect-pollination was assessed by emasculation and exposure to pollinators in the natural population. The breeding system was also tested by pollination manipulations. Key Results Autonomous self-pollination occurred after flowers wilted. The stigmatic fluid formed a globule on the stigma on the third day of flowering. The enlarged globule seeped into the nearby pollen grains on the fourth flowering day, thus inducing pollen germination. Pollen tubes then elongated and penetrated the stigma. Hand-selfed flowers produced as many seeds as hand-crossed flowers. There was no significant difference in seed production between pollinator-excluded flowers and hand-selfed flowers. When emasculated flowers were exposed to pollinators, they produced significantly fewer seeds than intact flowers. Visits by effective pollinators were rare. Conclusions This study describes a new form of delayed autonomous self-pollination. As the predominant mechanism of sexual reproduction in R. debilis, delayed self-pollination ensures reproduction when pollinators are scarce.

Fan, Yong-Li; Li, Qing-Jun

2012-01-01

371

Mechanical stability of micropipet-aspirated giant vesicles with fluid phase coexistence.  

PubMed

Micropipet aspiration of phase-separated lipid bilayer vesicles can elucidate physicochemical aspects of membrane fluid phase coexistence. Recently, we investigated the composition dependence of line tension at the boundary between liquid-ordered and liquid-disordered phases of giant unilamellar vesicles obtained from ternary lipid mixtures using this approach. Here we examine mechanical equilibria and stability of dumbbell-shaped vesicles deformed by line tension. We present a relationship between the pipet aspiration pressure and the aspiration length in vesicles with two coexisting phases. Using a strikingly simple mechanical model for the free energy of the vesicle, we predict a relation that is in almost quantitative agreement with experiment. The model considers the vesicle free energy to be proportional to line tension and assumes that the vesicle volume, domain area fraction, and total area are conserved during aspiration. We also examine a mechanical instability encountered when releasing a vesicle from the pipet. We find that this releasing instability is observed within the framework of our model that predicts a change of the compressibility of a pipet-aspirated membrane cylinder from positive (i.e., stable) to negative (unstable) values, at the experimental instability. The model furthermore includes an aspiration instability that has also previously been experimentally described. Our method of studying micropipet-induced shape transitions in giant vesicles with fluid domains could be useful for investigating vesicle shape transitions modulated by bending stiffness and line tension. PMID:18717549

Das, Sovan; Tian, Aiwei; Baumgart, Tobias

2008-08-22

372

Modelling of fluid-mechanical arc instability in pure-mercury HID lamps  

NASA Astrophysics Data System (ADS)

A fully unsteady compressible 2D flow model is used to reproduce observed fluid-mechanical arc instability in a horizontally-running pure-mercury HID lamp. The model represents a 2D lamp cross-section normal to the arc, and assumes an infinitely long lamp. Departure from the steady condition is driven by oscillating lamp current. Sound-wave propagation and induced flows result from full coupling between the current, energy balance, ideal-gas law and conservation of mass and momentum, on two separate relevant time scales. Observed acoustically generated arc instability is reproduced with the model.

Dreeben, Thomas D.

2008-07-01

373

Fluid Mechanics and Public Policy including natural disasters and climate change  

NASA Astrophysics Data System (ADS)

Where public policy relies on science for dealing with important issues affecting society, scientists involved have to explain what is known, what is uncertain, what might be known with more research and how to integrate science into decisions. Lessons have been learnt about all these stages in recent science-policy issues. Fluid mechanics and related sciences are contributing significantly to many problems. Some are specific such as the internal structure of extreme flow events in the atmosphere and ocean, or the microphysics of particle coagulation in narrow passages; others are system problems such as the environmental risks of growing mega cities, or combinations of processes affecting global and regional climate change.

Hunt, Julian

2011-11-01

374

[Study on electrochemical mechanism of coronary stent used austenitic stainless steel in flowing artificial body fluid].  

PubMed

The electrochemical mechanism of austenitic stainless steel (SUS316L and SUS317L) coronary stents in flowing artificial body fluid has been investigated with electrochemical technologies. The results indicated that the flowing medium coursed the samples' pitting potential Eb shift negatively, increased the pitting corrosion sensitivity, accelerated its anodic dissolution, but had little effects on repassivated potential. The flowing environment had great effects on cathodic process. The oxygen reaction on the samples' surface became faster as the cathodic process was not controlled by oxygen diffusion but by mixed diffusion and electrochemical process. With the increase of velocity of solution, the pitting corrosion becomes liable to occur under this circumstance. PMID:16156260

Liang, Chenghao; Guo, Liang; Chen, Wan; Wang, Hua

2005-08-01

375

A novel mechanism of insect resistance engineered into tobacco  

NASA Astrophysics Data System (ADS)

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.

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

1987-11-01

376

Mechanism of vibration-induced repulsion force on a particle in a viscous fluid cell.  

PubMed

Space platforms such as the Space Shuttle and International Space Station have been considered an ideal environment for production of protein and semiconductor crystals of superior quality due to the negligible gravity-induced convection. Although it was believed that under microgravity environment diffusive mass transport would dominate the growth of the crystals, some related experiments have not shown satisfactory results possibly due to the movement of the growing crystals in fluid cells caused by small vibrations present in the space platforms called g-jitter. In ground-based experiments, there have been clear observations of attraction and repulsion of a solid particle with respect to a nearby wall of the fluid cell due to small vibrations. The present work is a numerical investigation on the physical mechanisms responsible for the repulsion force, which has been predicted to increase with the cell vibration frequency and amplitude, as well as the fluid viscosity. Moreover, the simulations have revealed that the repulsion force occurs mostly due to the increased pressure in the narrow gap between the particle and the nearest wall. PMID:24032936

Saadatmand, Mehrrad; Kawaji, Masahiro

2013-08-19

377

Mechanism of vibration-induced repulsion force on a particle in a viscous fluid cell  

NASA Astrophysics Data System (ADS)

Space platforms such as the Space Shuttle and International Space Station have been considered an ideal environment for production of protein and semiconductor crystals of superior quality due to the negligible gravity-induced convection. Although it was believed that under microgravity environment diffusive mass transport would dominate the growth of the crystals, some related experiments have not shown satisfactory results possibly due to the movement of the growing crystals in fluid cells caused by small vibrations present in the space platforms called g-jitter. In ground-based experiments, there have been clear observations of attraction and repulsion of a solid particle with respect to a nearby wall of the fluid cell due to small vibrations. The present work is a numerical investigation on the physical mechanisms responsible for the repulsion force, which has been predicted to increase with the cell vibration frequency and amplitude, as well as the fluid viscosity. Moreover, the simulations have revealed that the repulsion force occurs mostly due to the increased pressure in the narrow gap between the particle and the nearest wall.

Saadatmand, Mehrrad; Kawaji, Masahiro

2013-08-01

378

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

ERIC Educational Resources Information Center

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,…

Hamlin, Larry

379

Inflammatory mechanisms of atheroma formation. Influence of fluid mechanics and lipid-derived inflammatory mediators.  

PubMed

It has been suggested that atheroma formation is a chronic inflammatory response to lipid-derived inflammatory mediators accumulating at selected arterial sites. At large artery flow dividers and curvatures, secondary flow phenomena create zones of stagnation and recirculation that deprive endothelial cells of shear stress-induced differentiation. Endothelial cell phenotypes at these sites appear to represent activated cells expressing membrane-associated and secreted molecules that favor constriction, permeability, leukocyte adhesion, thrombosis, and proliferation. Altered endothelial synthetic activities include an increased production of matrix proteins that may underlie intimal thickening at flow dividers and curvatures. In the presence of hyperlipoproteinemia, endothelial hyperpermeability, as determined by flow mechanics, and accumulation of subendothelial matrix proteins may favor intimal uptake and retention of low-density lipoprotein (LDL). Local oxidative degradation of trapped LDL may generate lipid-derived inflammatory mediators, such as oxysterols, peroxidized fatty acids, and lysophospholipids. Proinflammatory properties of the latter can explain some of the effects that are necessary for generating atherogenic mononuclear (monocytic/T-lymphocytic) inflammatory responses in arterial walls. PMID:8297540

Henry, P D; Chen, C H

1993-11-01

380

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

PubMed

Nanoindentation is a technique for measuring the elastic modulus and hardness of small amounts of materials. This method, which has been used extensively for characterizing metallic and inorganic solids, is now being applied to organic and metal-organic crystals, and has also become relevant to the subject of crystal engineering, which is concerned with the design of molecular solids with desired properties and functions. Through nanoindentation it is possible to correlate molecular-level properties such as crystal packing, interaction characteristics, and the inherent anisotropy with micro/macroscopic events such as desolvation, domain coexistence, layer migration, polymorphism, and solid-state reactivity. Recent developments and exciting opportunities in this area are highlighted in this Minireview. PMID:23315913

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

2013-01-11

381

Engineering of mechanical manufacturing from the cradle to cradle  

NASA Astrophysics Data System (ADS)

The sustainability of manufacturing processes lies in industrial planning and productive activity. Industrial plants are characterized by the management of resource (inputs and outputs), processing and conversion processes, which usually are organized in a linear system. Good planning will optimize the manufacturing and promoting the quality of the industrial system. Cradle to Cradle is a new paradigm for engineering and sustainable manufacturing that integrates projects (industrial parks, manufacturing plants, systems and products) in a framework consistent with the environment, adapted to the society and technology and economically viable. To carry it out, we implement this paradigm in the MGE2 (Genomic Model of Eco-innovation and Eco-design), as a methodology for designing and developing products and manufacturing systems with an approach from the cradle to cradle.

Peralta, M. E.; Aguayo, F.; Lama, J. R.

2012-04-01

382

Stirling engine power control and motion conversion mechanism  

DOEpatents

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.

Marks, David T. (Birmingham, MI)

1983-01-01

383

The effect of fluid mechanics on graphene growths by chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Graphene's unique mechanical, electrical, and thermal properties have made it a very attractive material desired for use in future technologies. Over the recent years, there have been many breakthroughs in research on graphene. Recently, the focus of the latest research has shifted towards scaling graphene production for commercial use by industry. The most promising method for scaling graphene growth for industry usage is chemical vapor deposition (CVD). CVD is a low cost, economic and scalable method for producing graphene. However, consistently producing high quality graphene quickly on a large scale has eluded researchers. Here we detail a method for reducing growth time required to produce high quality, large area graphene by adjusting the fluid mechanics of the CVD.

Bell, Jeffrey M.; Ruiz, Isaac; Ozkan, Cengiz; Ozkan, Mihri; George, Aaron; Hosseinbay, Hamed

2013-09-01

384

Settling-driven convection: A mechanism of sedimentation from stratified fluids  

NASA Astrophysics Data System (ADS)

Convection driven by sediment particles may play an important role in sedimentation from the base of buoyant (hypopycnal) plumes, for example, fluvial plumes in stratified estuaries and lakes, black smokers on the ocean floor, volcanic clouds, and coastal currents. In addition to the well-known double-diffusive convection mechanism, another mode of convective instability development is by settling across the density interface. We performed laboratory experiments to investigate this fingering/convective instability mechanism and its effect on particle distribution in the water column and deposition at the bed. A simple theoretical model of finger formation at a fluid density interface is developed based on an analogy with thermal/plume formation at a flat heated plate. This model, which involves a thickening interface layer that becomes gravitationally unstable relative to the ambient fluid, is in good agreement with measurements of finger size and instability wavelength from visualization experiments. Since fingering at the density interface drives larger-scale convection in the fluid below, a mass balance model of the lower layer, assuming strong mixing (i.e., uniform sediment concentration) is successfully applied to predict sediment concentration in the water column and deposition at the bed. Strong mixing can be assumed since convective velocities are usually much greater than the particle fall velocities. As convection proceeds, the sediment concentrations in the two layers approach each other and convection will die out. Using the model equations, we develop analytical expressions for the time when convection ceases and the portion of sediment remaining in the water column.

Hoyal, David C. J. D.; Bursik, Marcus I.; Atkinson, Joseph F.

1999-04-01

385

SUPG and discontinuity-capturing methods for coupled fluid mechanics and electrochemical transport problems  

NASA Astrophysics Data System (ADS)

Electrophoresis is the motion of charged particles relative to the surrounding liquid under the influence of an external electric field. This electrochemical transport process is used in many scientific and technological areas to separate chemical species. Modeling and simulation of electrophoretic transport enables a better understanding of the physicochemical processes developed during the electrophoretic separations and the optimization of various parameters of the electrophoresis devices and their performance. Electrophoretic transport is a multiphysics and multiscale problem. Mass transport, fluid mechanics, electric problems, and their interactions have to be solved in domains with length scales ranging from nanometers to centimeters. We use a finite element method for the computations. Without proper numerical stabilization, computation of coupled fluid mechanics, electrophoretic transport, and electric problems would suffer from spurious oscillations that are related to the high values of the local Péclet and Reynolds numbers and the nonzero divergence of the migration field. To overcome these computational challenges, we propose a stabilized finite element method based on the Streamline-Upwind/Petrov-Galerkin (SUPG) formulation and discontinuity-capturing techniques. To demonstrate the effectiveness of the stabilized formulation, we present test computations with 1D, 2D, and 3D electrophoretic transport problems of technological interest.

Kler, Pablo A.; Dalcin, Lisandro D.; Paz, Rodrigo R.; Tezduyar, Tayfun E.

2013-02-01

386

The mechanics of microparticle collection in an open fluid volume undergoing low frequency horizontal vibration  

NASA Astrophysics Data System (ADS)

Manipulation of particles suspended in a fluid can be achieved using low frequency vibrations in an open fluid volume. The collection of particles at the solid-liquid (lower) interface is attributed to the generation of resonant capillary waves at the liquid-air (upper) interface. The resulting periodic flow field points to a hydrodynamic focusing mechanism which collects the particles over multiple cycles. This collection process is demonstrated by modelling the flow field produced in an open rectangular chamber undergoing horizontal oscillation. A particle tracing algorithm is then used to predict the collection locations of particles at different regions in the chamber. The modelling allows the collection mechanism to be understood and the effect of particle inertia on the process to be investigated; as a result, the speed of collection can be described as a function of particle size and density. The modelling results are supported by experimental observations in a rectangular well filled with water; the data show that particles with higher inertia collect faster. The effect of streaming is also observed in the experiments for particles with lower inertia.

Agrawal, Prashant; Gandhi, Prasanna S.; Neild, Adrian

2013-09-01

387

Mechanical efficiency considerations in the design of an ultra low temperature differential Stirling engine  

NASA Astrophysics Data System (ADS)

The study shows how a recently developed theory of mechanical efficiency can be employed in guiding the design of a particular engine. The subject engine is a Stirling intended to operate on a very small temperature difference across the warm and cool sides. The project's end product is a small kinematic Stirling engine capable of operating down to a temperature differential of only 0.5 C. The engine easily runs from heat absorbed while resting on the palm of a human hand. It begins running within about 15 sec of being picked up, and afer a few minutes reaches steady state operation at about 80 rpm. A sectional view of the P-19 low Delta(T) kinematic Stirling engine is shown.

Senft, J. R.

388

Engineered disulfides improve mechanical properties of recombinant spider silk  

PubMed Central

Nature's high-performance polymer, spider silk, is composed of specific proteins, spidroins, which form solid fibers. So far, fibers made from recombinant spidroins have failed in replicating the extraordinary mechanical properties of the native material. A recombinant miniature spidroin consisting of four poly-Ala/Gly-rich tandem repeats and a nonrepetitive C-terminal domain (4RepCT) can be isolated in physiological buffers and undergoes self assembly into macrofibers. Herein, we have made a first attempt to improve the mechanical properties of 4RepCT fibers by selective introduction of AA ? CC mutations and by letting the fibers form under physiologically relevant redox conditions. Introduction of AA ? CC mutations in the first poly-Ala block in the miniature spidroin increases the stiffness and tensile strength without changes in ability to form fibers, or in fiber morphology. These improved mechanical properties correlate with degree of disulfide formation. AA ? CC mutations in the forth poly-Ala block, however, lead to premature aggregation of the protein, possibly due to disulfide bonding with a conserved Cys in the C-terminal domain. Replacement of this Cys with a Ser, lowers thermal stability but does not interfere with dimerization, fiber morphology or tensile strength. These results show that mutagenesis of 4RepCT can reveal spidroin structure-activity relationships and generate recombinant fibers with improved mechanical properties.

Grip, S; Johansson, J; Hedhammar, M

2009-01-01

389

Novel mechanically competent polysaccharide scaffolds for bone tissue engineering  

Microsoft Academic Search

The success of the scaffold-based bone regeneration approach critically depends on the biomaterial's mechanical and biological properties. Cellulose and its derivatives are inherently associated with exceptional strength and biocompatibility due to their ?-glycosidic linkage and extensive hydrogen bonding. This polymer class has a long medical history as a dialysis membrane, wound care system and pharmaceutical excipient. Recently cellulose-based scaffolds have

S G Kumbar; M Deng; R James; C T Laurencin; A Aravamudhan; M Harmon; D M Ramos

2011-01-01

390

Web-Based Java Applets for Teaching Engineering Mechanics  

Microsoft Academic Search

A series of novel Web-based instructional units for teaching structural mechanics to undergraduate students are developed. The instructional units are centered on computer programs written in the platform independent object-oriented Java programming language. The Java applications are embedded in World Wide Web pages (where they are called applets) and are thus available via the Internet to students and instructors throughout

Kamal B. Rojiani; Yong Y. Kim; Rakesh K. Kapania

391

Engineering aspects of a molten salt heat transfer fluid in a trough solar field  

Microsoft Academic Search

An evaluation was carried out to investigate the feasibility of utilizing a molten salt as the heat transfer fluid (HTF) and for thermal storage in a parabolic trough solar field to improve system performance and to reduce the levelized electricity cost. The operating large-scale solar parabolic trough plants in the USA currently use a high temperature synthetic oil in the

D. Kearney; B. Kelly; U. Herrmann; R. Cable; J. Pacheco; R. Mahoney; H. Price; D. Blake; P. Nava; N. Potrovitza

2004-01-01

392

Pulse pressure variation and stroke volume variation predict fluid responsiveness in mechanically ventilated patients experiencing intra-abdominal hypertension.  

PubMed

The purpose of the present study was to evaluate whether pulse pressure variation (PPV) and stroke volume variation (SVV) can predict fluid responsiveness in patients with intra-abdominal hypertension (IAH) in either a supine or Trendelenburg position. Forty mechanically ventilated patients that exhibited IAH resulting from carbon dioxide insufflation (up to 12 mmHg) underwent fluid therapy in either a supine or Trendelenburg position. Hemodynamic measurements, including PPV and SVV, were obtained before and after fluid therapy. Prediction of fluid responsiveness (> 10% increase in stroke volume) was performed by linear regression analyses. Baseline PPV and SVV values correlated closely with changes in stroke volume induced by fluid therapy, and were significantly higher in patients that subsequently responded to fluid therapy. Fluid responsiveness in patients in a supine position was predicted by a PPV threshold of > 10.5% and an SVV threshold of > 10.5%. Fluid responsiveness in patients in a Trendelenburg position was predicted by a PPV threshold of > 7.5% and an SVV threshold of > 7.0%. PPV and SVV were demonstrated to be sensitive and specific predictors of fluid responsiveness in patients with IAH in both the supine and Trendelenburg positions. PMID:23612080

Liu, Xiaomei; Fu, Qiang; Mi, Weidong; Liu, Henian; Zhang, Hong; Wang, Peiji

2013-04-01

393

Reverse Engineering of Mechanical Components within a Computer-aided Design\\/Computer-aided Manufacturing Environment  

Microsoft Academic Search

The problem of reverse engineering (RE) is defined. Potential applications of the RE process in various areas of mechanical engineering are described. The issues that must be resolved to obtain an integrated computer-aided design\\/computer-aided manufacturing\\/RE system are identified. A prototype was developed to demonstrate the feasibility of such a system and results are presented for a simple object

Vivek Kalra; Pradip N. Sheth; Larry G. Richards

1991-01-01

394

Feasibility of Reduced Chemical Kinetic Mechanisms of Methane in Internal Combustion Engine Simulations  

NASA Astrophysics Data System (ADS)

Three reduced chemical kinetic mechanisms of methane combustion were tested and compared with the standard detailed scheme GriMech 3.0., using the internal combustion engine (ICE) model of Chemkin 4.02 [1]. This study shows acceptable concordances in the prediction of temperature and main species profiles. But reduced schemes were incapables to predict all polluant emissions in an internal combustion engine.

Ennetta, Ridha; Said, Rachid

2008-09-01

395

Sealing Mechanism and Failure Analysis of Automotive Engine Crankshaft Oil Seal  

Microsoft Academic Search

There are many factors that lead to the failure of automotive engine crankshaft back oil seal, these factors include seal working condition, seal`s material quality and seal`s technical parameters that directly affect the seal`s seal ability and service life. Aiming at the leakage problem of automotive engine crankshaft oil seal and basing on analysis of drain pump seal mechanism, I

Aifang Yan; Qingping Yan

2012-01-01

396

Study of nonlinear processes of a large experimental thermoacoustic-Stirling heat engine by using computational fluid dynamics  

NASA Astrophysics Data System (ADS)

This article focuses on using computational fluid dynamics (CFD) method to study several important nonlinear phenomenon and processes of a large experimental thermoacoustic-Stirling heat engine. First, the simulated physical model was introduced, and the suitable numerical scheme and algorithm for the time-dependent compressible thermoacoustic system was determined through extensive numerical tests. Then, the simulation results of the entire evolution process of self-excited thermoacoustic oscillation and the acoustical characteristics of pressure and velocity waves were presented and analyzed. Especially, the onset temperature and the saturation process of dynamic pressure were captured by the CFD simulation. In addition, another important nonlinear phenomenon accompanying the acoustic wave, which is the steady mass flow through the traveling-wave loop inside the thermoacoustic engine, was studied. To suppress the steady mass flow numerically, a fan model was adopted in the simulation. Finally, the multidimensional effects of vortex formation in the thermal buffer tube and other components were displayed numerically. Most importantly, a substantial comparison between the simulation and experiments was made, which demonstrated well the validity and powerfulness of the CFD simulation for characterizing several complicated nonlinear phenomenon involved in the self-excited thermoacoustic heat engine.

Yu, G. Y.; Luo, E. C.; Dai, W.; Hu, J. Y.

2007-10-01

397

Computational fluid dynamics simulation of the air/suppressant flow in an uncluttered F18 engine nacelle  

SciTech Connect

For the purposes of designing improved Halon-alternative fire suppression strategies for aircraft applications, Computational Fluid Dynamics (CFD) simulations of the air flow, suppressant transport, and air-suppressant mixing within an uncluttered F18 engine nacelle were performed. The release of inert gases from a Solid Propellant Gas Generator (SPGG) was analyzed at two different injection locations in order to understand the effect of injection position on the flow patterns and the mixing of air and suppression agent. An uncluttered engine nacelle was simulated to provide insight into the global flow features as well as to promote comparisons with previous nacelle fire tests and recent water tunnel tests which included little or no clutter. Oxygen concentration levels, fuel/air residence times that would exist if a small fuel leak were present, velocity contours, and streamline patterns are presented inside the engine nacelle. The numerical results show the influence of the gent release location on regions of potential flame extinction due to oxygen inerting and high flame strain. The occurrence of inflow through the exhaust ducts on the aft end of the nacelle is also predicted. As expected, the predicted oxygen concentration levels were consistently higher than the measured levels since a fire was not modeled in this analysis. Despite differences in the conditions of these simulations and the experiments, good agreement was obtained between the CFD predictions and the experimental measurements.

Lopez, A.R.; Gritzo, L.A.; Hassan, B.

1997-06-01

398

Fluid Induced Microseismicity: A Possible Triggering Mechanism And Analysis For Reservoir Characterization  

NASA Astrophysics Data System (ADS)

The attention to the microseismic monitoring during operation of geothermal or hydrocarbon reservoirs has grown considerably over the last several years. The observation of microseismicity occurring during borehole fluid injections or extractions has a large potential in characterizing reservoirs in terms of their hydraulic properties as far as several kilometers from boreholes. An approach for the interpretation of microseismic data was proposed to provide in-situ estimates of hydraulic diffusivity or permeability characterizing a geothermal or hydrocarbon reservoirs on the large spatial scale (of the order of 103 m). We call this approach "Seismicity Based Reservoir Characterization" (SBRC). It considers microseismicity triggered by a pore pressure relaxation process at critically stressed locations in rocks. The approach uses a spatio-temporal analysis of fluid-injection induced microseismicity to reconstruct scalar values as well as the tensor of hydraulic diffusivity and to estimate the tensor of permeability for the seismically active volume. The method provides a possibility to invert for hydraulic diffusivity distributions in fluid-saturated rocks. Estimates of hydraulic diffusivity tensors on large spatial scales as well as imaging of its distributions in space resulting from this concept can be of significant importance for industrial applications and understanding of physical properties of geological structures. Here we introduce the fundamental concepts for the interpretation of microseismic data and show numerical verifications of the method. We propose an approach for the numerical modeling of microseismicity. We focus on the verification of the SBRC inversion algorithms using synthetic data. The results of numerical modeling show that in spite of the apparent simplicity of this approach it reproduces significant features of microseismicity observed in reality. The structure and temporal evolution of microseismicity clouds depends on hydraulic properties of rocks as well as on the statistics and spatial distribution of their criticality. The inversion algorithms have been successfully validated. We consider this as an indication that our description of the main physical features of the triggering phenomenon are adequate. The pore pressure relaxation process seems to be an important mechanism for triggering microearthquakes in fluid-saturated rocks. We also show the application of the SBRC approach to various data sets. Data examples of Hot Dry Rock experiments in crystalline rocks (Fenton Hill and Soultz sous Forêts) are presented as well as the analysis of microseismicity obtained during fluid injections in sedimentary environment. We show that it seems to be promising to apply the diffusion-process-based approach even for hydraulic fracturing experiments.

Rothert, E.; Shapiro, S. A.

2005-05-01

399

Wear mechanisms in moderate temperature gasoline engine service  

Microsoft Academic Search

The mechanism of overhead valve train wear in moderate to low temperature service was studied using a modified fired V-D test and a motored V-D cam and cam-follower rig. High wear and low wear used oils from the fired test gave the correct relative wear in the motored test, indicating the motored test in a valid tool for studying wear

C. T. West; C. A. Passut; E. Chamot

1986-01-01

400

A detailed fluid mechanics study of tilting disk mechanical heart valve closure and the implications to blood damage.  

PubMed

Hemolysis and thrombosis are among the most detrimental effects associated with mechanical heart valves. The strength and structure of the flows generated by the closure of mechanical heart valves can be correlated with the extent of blood damage. In this in vitro study, a tilting disk mechanical heart valve has been modified to measure the flow created within the valve housing during the closing phase. This is the first study to focus on the region just upstream of the mitral valve occluder during this part of the cardiac cycle, where cavitation is known to occur and blood damage is most severe. Closure of the tilting disk valve was studied in a "single shot" chamber driven by a pneumatic pump. Laser Doppler velocimetry was used to measure all three velocity components over a 30 ms period encompassing the initial valve impact and rebound. An acrylic window placed in the housing enabled us to make flow measurements as close as 200 microm away from the closed occluder. Velocity profiles reveal the development of an atrial vortex on the major orifice side of the valve shed off the tip of the leaflet. The vortex strength makes this region susceptible to cavitation. Mean and maximum axial velocities as high as 7 ms and 20 ms were recorded, respectively. At closure, peak wall shear rates of 80,000 s(-1) were calculated close to the valve tip. The region of the flow examined here has been identified as a likely location of hemolysis and thrombosis in tilting disk valves. The results of this first comprehensive study measuring the flow within the housing of a tilting disk valve may be helpful in minimizing the extent of blood damage through the combined efforts of experimental and computational fluid dynamics to improve mechanical heart valve designs. PMID:18601443

Manning, Keefe B; Herbertson, Luke H; Fontaine, Arnold A; Deutsch, Steven

2008-08-01

401

Stable Small Animal Mechanical Ventilation for Dynamic Lung Imaging to Support Computational Fluid Dynamics Models  

SciTech Connect

Pulmonary computational fluid dynamics models require 3D images to be acquired over multiple points in the dynamic breathing cycle, with no breath holds or changes in ventilatory mechanics. With small animals, these requirements result in long imaging times ({approx}90 minutes), over which lung mechanics, such as compliance, can gradually change if not carefully monitored and controlled. These changes, caused by derecruitment of parenchymal tissue, are manifested as an upward drift in peak inspiratory pressure or by changes in the pressure waveform and/or lung volume over the course of the experiment. We demonstrate highly repeatable mechanical ventilation in anesthetized rats over a long duration for pulmonary CT imaging throughout the dynamic breathing cycle. We describe significant updates to a basic commercial ventilator that was acquired for these experiments. Key to achieving consistent results was the implementation of periodic deep breaths, or sighs, of extended duration to maintain lung recruitment. In addition, continuous monitoring of breath-to-breath pressure and volume waveforms and long-term trends in peak inspiratory pressure and flow provide diagnostics of changes in breathing mechanics.

Jacob, Rick E.; Lamm, W. J.

2011-11-08

402

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

NASA Astrophysics Data System (ADS)

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.

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

403

Enhancing Student Learning in Food Engineering Using Computational Fluid Dynamics Simulations  

ERIC Educational Resources Information Center

|The current generation of students coming into food science and engineering programs is very visually oriented from their early experiences. To increase their interest in learning, new and visually appealing teaching materials need to be developed. Two diverse groups of students may be identified based on their math skills. Food science students…

Wong, Shin Y.; Connelly, Robin K.; Hartel, Richard W.

2010-01-01

404

Computational Fluid Dynamics Modelling of Residual Fuel Oil Combustion in the Context of Marine Diesel Engines  

Microsoft Academic Search

A simplified model is presented for vaporization and combustion of heavy residual based fuel oil in high-pressure sprays, in the context of marine diesel engines. The fuel is considered as a mix of residual base and cutter stock. The model accounts for multiple fuel components as well as limited diffusion rates and thermal decomposition rates within droplets by the use

L Goldsworthy

2006-01-01

405

Mechanical Engineering Safety Note PEPC Spreader Bar Assembly  

SciTech Connect

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.

Mason, D.

2001-08-26

406

Corrosion-inhibiting gas-turbine engine lubricant. II. Fluid formulation and evaluation  

Microsoft Academic Search

The corrosion-inhibiting capability of over one hundred candidate materials was assessed using the Corrosion Rate Evaluation Procedure (CREP). The candidate inhibitors were evaluated in single-additive and two-additive combinations formulated into a qualified MIL-L-7808H fluid. Several physical property measurements, including total acid number, flash point, and foaming characteristics, were used to screen various candidate inhibitors and inhibitor combinations. The more promising

P. A. Warner; W. E. Ward

1984-01-01

407

Mechanical loading by fluid shear stress enhances IGF-1 receptor signaling in osteoblasts in a PKCzeta-dependent manner.  

PubMed

Maintenance of optimal bone physiology requires the coordinated activity of osteoclasts that resorb old bone and osteoblasts that deposit new bone. Mechanical loading of bone and the resulting movement of interstitial fluid within the spaces surrounding bone cells is thought to play a key role is maintaining optimal bone mass. One way in which fluid movement may promote bone formation is by enhancing osteoblast survival. We have shown previously that application of fluid flow to osteoblasts in vitro confers a protective effect by inhibiting osteoblast apoptosis (Pavalko et al., 2003, J. Cell Physiol., 194: 194-205). To investigate the cellular mechanisms that regulate the response of osteoblasts to fluid shear stress, we have examined the possible interaction between fluid flow and growth factors in MC3T3-E1 osteoblast-like cells. We found that insulin-like growth factor-I (IGF-I) was significantly more effective at preventing TNF-alpha-induced apoptosis when cells were first subjected to mechanical loading by exposure to either unidirectional or oscillatory fluid flow compared to cells that were maintained in static culture. Additionally, downstream signaling in response to treatment with IGF-I, including ERK and Akt activation, was enhanced in cells that were subjected to fluid flow, compared to cells maintained in static culture. Furthermore, we found that PKC activity is essential for fluid shear stress sensitization of IGF-IR, since a specific inhibitor of PCKzeta function blocked the flow-enhanced IGF-I-activated Akt and ERK phosphorylation. Together, our results suggest that fluid shear stress may regulate IGF-I signaling in osteoblasts in a PKC-zeta-dependent manner. PMID:17879768

Triplett, Jason W; O'Riley, Rita; Tekulve, Kristyn; Norvell, Suzanne M; Pavalko, Fredrick M

2007-03-01

408

Long term culture of epithelia in a continuous fluid gradient for biomaterial testing and tissue engineering.  

PubMed

Epithelia perform barrier functions being exposed to different fluids on the luminal and basal side. For long-term testing of new biomaterials as artificial basement membrane substitutes, it is important to simulate this fluid gradient. Individually-selected biomaterials can be placed in tissue carriers and in gradient containers, where different media are superfused. Epithelia growing on the tissue carriers form a physiological barrier during the whole culture period. Frequently however, pressure differences between the luminal and basal compartments occur. This is caused by a unilateral accumulation of gas bubbles in the container compartments resulting in tissue damage. Consequently, the occurence of gas bubbles has to be minimized. Air bubbles in the perfusion culture medium preferentially accumulate at sites where different materials come into contact. The first development is new screw caps for media bottles, specifically designed to allow fluid contact with only the tube and not the cap material. The second development is the separation of remaining gas bubbles from the liquid phase in the medium using newly-developed gas expander modules. By the application of these new tools, the yield of embryonic renal collecting duct epithelia with intact barrier function on a fragile natural support material can be significantly increased compared to earlier experiments. PMID:11484942

Minuth, W W; Strehl, R; Schumacher, K; de Vries, U

2001-01-01

409

Experimental investigations on the fluid flow mechanism in porous media of enhanced oil recovery by alkli\\/surfactant\\/polymer flooding  

Microsoft Academic Search

The fluid flow mechanism in porous media of enhanced oil recovery by Alkli\\/ Surfactant\\/Polymer (ASP) flooding is investigated\\u000a by measuring production performance, pressure distribution and saturation distribution through installing differential pressure\\u000a transducers and saturation measuring probes in a physical model of vertical heterogeneous reservoir. The fluid flow variation\\u000a in porous media is the main reason of enhanced oil recovery of

Jialu Wang; Pingping Shen; Yongzhong Chen; Zubo Zhang; Xu Jia; Yuling Tian

2005-01-01

410

Fluid mechanics of distallation trays (I): Depth-averaged theory and one-dimensional flows  

SciTech Connect

Rigorous design of a distillation column requires a better fundamental understanding of the fluid mechanics of bubble formation and global flows on trays than that currently available. To progress beyond the empirical- or correlation-based state of understanding that currently exists, a theoretical and computational framework is described here that is based on reducing the governing set of three-dimensional conservation equations to a two-dimensional set by averaging them across the depth of the fluid film flowing across the tray. In contrast to related previous works, realistic boundary conditions to the flow problem are provided in this paper by solving simultaneously for the flow on the tray and its inlet and outlet downcomers. In this first of a series of papers, attention is focused on situations in which the flow is invariant in the direction perpendicular to the main flow direction. By means of such a set of one-dimensional, depth-averaged equations, predictions are made in several interesting and practically important situations in which the flow is either steady or time dependent.

Wohlhuter, F.K. [Univ. of Tennessee, Knoxville, TN (United States); Basaran, O.A. [Oak Ridge National Laboratory, TN (United States); Harriott, G.M. [Air Products and Chemicals, Inc., Allentown, PA (United States)

1995-04-01

411

Effects of Mechanical Stretch on Collagen and Cross-Linking in Engineered Blood Vessels  

PubMed Central

It has been shown that mechanical stimulation affects the physical properties of multiple types of engineered tissues. However, the optimum regimen for applying cyclic radial stretch to engineered arteries is not well understood. To this end, the effect of mechanical stretch on the development of engineered blood vessels was analyzed in constructs grown from porcine vascular smooth muscle cells. Cyclic radial distension was applied during vessel culture at three rates: 0 beats per minute (bpm), 90 bpm, and 165 bpm. At the end of the 7-week culture period, harvested vessels were analyzed with respect to physical characteristics. Importantly, mechanical stretch at 165 bpm resulted in a significant increase in rupture strength in engineered constructs over nonstretched controls. Stress–strain data and maximal elastic moduli from vessels grown at the three stretch rates indicate enhanced physical properties with increasing pulse rate. In order to investigate the role of collagen cross-linking in the improved mechanical characteristics, collagen cross-link density was quantified by HPLC. Vessels grown with mechanical stretch had somewhat more collagen and higher burst pressures than nonpulsed control vessels. Pulsation did not increase collagen cross-link density. Thus, increased wall thickness and somewhat elevated collagen concentrations, but not collagen cross-link density, appeared to be responsible for increased burst strength.

Solan, Amy; Dahl, Shannon L. M.; Niklason, Laura E.

2009-01-01

412

A fluid mechanical model for mixing in a plankton predator-prey system  

NASA Astrophysics Data System (ADS)

A Lagrangian method is developed to study mixing of small particles in open flows. Particle Lagrangian Coherent Structures (pLCS) are identified as transport barriers in the dynamical systems of particles. We apply this method to a planktonic predator-prey system in which moon jellyfish Aurelia aurita uses its body motion to generate fluid currents which carry their prey to the vicinity of their capture appendages. With the flow generated by the jellyfish experimentally measured and the dynamics of prey particles in the flow described by a modified Maxey-Riley equation, we use pLCS to identify the capture region in which prey can be captured. The properties of the capture region enable analysis of the effects of several physiological and mechanical parameters on the predator-prey interaction, such as prey size, escape force, predator perception, etc. The method provides a new methodology to study dynamics and mixing of small organisms in general.

Peng, J.; Dabiri, J. O.

2009-04-01

413

Effects of fluid and light dynamics on H2 production in a mechanically stirred photobioreactor.  

PubMed

Hydrogen productions through biophotolysis by microalgae in photobioreactors (PBRs) were studied using a computational model integrated with fluid dynamics, particle tracking technique, light attenuation dynamics, biochemical kinetics, and mass transport. The trajectories of microalgae entrained in the flow fields within these PBRs were traced by the particle tracking technique and were used to determine the dynamics of light attenuation subjected by the cells, which were analyzed and compared with those obtained from the unstirred PBR under different incident light illuminations. The results show an improvement on the light penetration depth in the mechanically stirred cultures. The dynamics of light attenuation was incorporated into the kinetics equations for the analysis of the inhomogeneous biochemical process for hydrogen production by microalgae. Hydrogen production in the unstirred and the impeller-stirred PBRs were determined under different light illumination conditions and the results show an improvement on hydrogen production in the impeller-stirred PBRs. PMID:23911818

Zhang, T

2013-07-17

414

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

Microsoft Academic Search

CFD analyses of the Space Transportation Main Engine film\\/dump cooled subscale nozzle are presented, with an emphasis on the timely impact of CFD in the design of the subscale nozzle secondary coolant system. Calculations were performed with the Generalized Aerodynamic Simulation Program (GASP), using a Baldwin-Lomas Turbulence model, and finite rate hydrogen-oxygen chemistry. Design iterations for both the secondary coolant

J. L. Garrett; S. A. Syed

1992-01-01

415

Silicon-based tracking system: Mechanical engineering and design  

SciTech Connect

The Silicon Tracking System (STS) is composed of silicon strip detectors arranged by both in a cylindrical array and an array of flat panels about the interaction region. The cylindrical array is denoted the central region and the flat panel arrays, which are normal to the beam axis, we denoted the forward regions. The overall length of the silicon array is 5.16 m and the maximum diameter is 0.93 m. The Silicon Tracking System Conceptual Design Report, should be consulted for the body of analysis performed to quantify the present design concept. For the STS to achieve its physics goals, the mechanical structures and services must support 17 m{sup 2} of silicon detectors and stabilize their positions to within 5 {mu}m, uniformly cool the detector the system to O{degrees} C and at the same time potentially remove up to 13 kW of waste heat generated by the detector electronics, provide up to 3400 A of current to supply the 6.5 million electronics channels, and supply of control and data transmission lines for those channels. These objectives must be achieved in a high ionizing radiation environment, using virtually no structural mass and only low-Z materials. The system must be maintainable during its 10 year operating life.

Miller, W.O.; Gamble, M.T.; Thompson, T.C.; Woloshun, K.A.; Reid, R.S.; Hanlon, J.A.; Michaud, F.D.; Dransfield, G.D.; Ziock, H.J.; Palounek, A.P.

1992-01-01

416

Wear mechanism and wear prevention in coal-fueled diesel engines  

SciTech Connect

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.

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

1991-10-01

417

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

SciTech Connect

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.

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

1991-10-01

418

Structure and Dynamics of Fluids in Microporous and Mesoporous Earth and Engineered Materials  

NASA Astrophysics Data System (ADS)

The behavior of liquids in confined geometries (pores, fractures) typically differs, due to the effects of large internal surfaces and geometrical confinement, from their bulk behavior in many ways. Phase transitions (i.e., freezing and capillary condensation), sorption and wetting, and dynamical properties, including diffusion and relaxation, may be modified, with the strongest changes observed for pores ranging in size from <2 to 50 nm—the micro- and mesoporous regimes. Important factors influencing the structure and dynamics of confined liquids include the average pore size and pore size distribution, the degree of pore interconnection, and the character of the liquid-surface interaction. While confinement of liquids in hydrophobic matrices, such as carbon nanotubes, or near the surfaces of mixed character, such as many proteins, has also been an area of rapidly growing interest, the confining matrices of interest to earth and materials sciences usually contain oxide structural units and thus are hydrophilic. The pore size distribution and the degree of porosity and inter-connection vary greatly amongst porous matrices. Vycor, xerogels, aerogels, and rocks possess irregular porous structures, whereas mesoporous silicas (e.g., SBA-15, MCM-41, MCM-48), zeolites, and layered systems, for instance clays, have high degrees of internal order. The pore type and size may be tailored by means of adjusting the synthesis regimen. In clays, the interlayer distance may depend on the level of hydration. Although studied less frequently, matrices such as artificial opals and chrysotile asbestos represent other interesting examples of ordered porous structures. The properties of neutrons make them an ideal probe for comparing the properties of bulk fluids with those in confined geometries. In this chapter, we provide a brief review of research performed on liquids confined in materials of interest to the earth and material sciences (silicas, aluminas, zeolites, clays, rocks, etc.), emphasizing those neutron scattering techniques that assess both structural modification and dynamical behavior. Quantitative understanding of the complex solid-fluid interactions under different thermodynamic situations will impact both the design of better substrates for technological applications (e.g., chromatography, fluid capture, storage and release, and heterogeneous catalysis) as well as our fundamental understanding of processes encountered in the environment (i.e., fluid and waste mitigation, carbon sequestration, etc.).

Cole, David R.; Mamontov, Eugene; Rother, Gernot

419

Sructure and dynamics of fluids in micropous and mesoporous earth and engineered materials  

SciTech Connect

The behavior of liquids in confined geometries (pores, fractures) typically differs, due to the effects of large internal surfaces and geometri-cal confinement, from their bulk behavior in many ways. Phase transitions (i.e., freezing and capillary condensation), sorption and wetting, and dy-namical properties, including diffusion and relaxation, may be modified, with the strongest changes observed for pores ranging in size from <2 nm to 50 nm the micro- and mesoporous regimes. Important factors influ-encing the structure and dynamics of confined liquids include the average pore size and pore size distribution, the degree of pore interconnection, and the character of the liquid-surface interaction. While confinement of liq-uids in hydrophobic matrices, such as carbon nanotubes, or near the sur-faces of mixed character, such as many proteins, has also been an area of rapidly growing interest, the confining matrices of interest to earth and ma-terials sciences usually contain oxide structural units and thus are hydro-philic. The pore size distribution and the degree of porosity and inter-connection vary greatly amongst porous matrices. Vycor, xerogels, aerogels, and rocks possess irregular porous structures, whereas mesopor-ous silicas (e.g., SBA-15, MCM-41, MCM-48), zeolites, and layered sys-tems, for instance clays, have high degrees of internal order. The pore type and size may be tailored by means of adjusting the synthesis regimen. In clays, the interlayer distance may depend on the level of hydration. Al-though studied less frequently, matrices such as artificial opals and chry-sotile asbestos represent other interesting examples of ordered porous structures. The properties of neutrons make them an ideal probe for com-paring the properties of bulk fluids with those in confined geometries. In this chapter, we provide a brief review of research performed on liquids confined in materials of interest to the earth and material sciences (silicas, aluminas, zeolites, clays, rocks, etc.), emphasizing those neutron scattering techniques which assess both structural modification and dynamical behav-ior. Quantitative understanding of the complex solid-fluid interactions under different thermodynamic situations will impact both the design of bet-ter substrates for technological applications (e.g., chromatography, fluid capture, storage and release, and heterogeneous catalysis) as well as our fundamental understanding of processes encountered in the environment (i.e., fluid and waste mitigation, carbon sequestration, etc.).

Cole, David R [ORNL; Mamontov, Eugene [ORNL; Rother, Gernot [ORNL

2009-01-01

420

Overpressured fluid imaging from focal mechanisms during the 2003-2004 Ubaye seismic swarm (Southern-Alps, France)  

NASA Astrophysics Data System (ADS)

The development of fluid pressure is thought to play a major role in earthquake triggering and in fault reactivation (Nur & Booker, 1972; Sibson, 1985; Miller et al., 2004; Hainzl et al., 2006; Cappa et al., 2009; Terakawa et al., 2010) In this study, we present an analysis of the potential key role of fluid pressure on the triggering of the 2003-2004 Ubaye (France) seismic swarm. Our aim is to provide a better understanding of fluid pressure build-up along fault zones and its influence on earthquake triggering. More than 16,000 microseismic events were detected during the Ubaye swarm. This swarm occurred over an area located between the Argentera-Mercantour and the Pelvoux crystalline massifs, below the Embrunais-Ubaye nappes (Jenatton et al., 2007). Hypocentral depths were comprised between 3 and 8 km and the spatial distribution of hypocenters was parallel to the azimuth of major regional NW-SE faults. This suggests that seismic ruptures reactivated a preexisting fault zone in the crystalline basement (Leclère et al., in press). Based on Mohr-Coulomb theory and a fault zone orientation of the seismic swarm computed by Daniel et al. (2011), we estimate the overpressured fluid required to reactivate this fault to be between 7 and 26 MPa (Leclère et al., in press). This result is in good agreement with a previous study by Daniel et al. (2011). We propose a mechanism for the development of overpressured fluid conditions that accounts for the presence of thermal springs, fault zone compaction processes and hydraulic barriers (Leclère et al., in press). In a further step, we analyze an extended focal mechanism dataset and we focus on overpressured fluid conditions required to reactivate individual fault planes related to each focal mechanism. We then investigate the correlation between changes in overpressured fluid conditions and changes in the seismicity rate. We also discuss the spatial heterogeneity of overpressured fluid conditions.

Leclère, H.; Daniel, G.; Fabbri, O.; Cappa, F.

2012-04-01

421

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

PubMed

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

Green, Christopher D

2005-02-01

422

Decoupling cell and matrix mechanics in engineered microtissues using magnetically actuated microcantilevers.  

PubMed

A novel bio-magnetomechanical microtissue system is described for magnetic actuation of arrays of 3D microtissues using microcantilevers. This system enables both in situ measurements of fundamental mechanical properties of engineered tissue, such as contractility and stiffness, as well as dynamic stimulation of the microtissues. Using this system, cell and extracellular matrix contributions to the tissue mechanical properties are decoupled for the first time under both static and dynamic loading conditions. PMID:23355085

Zhao, Ruogang; Boudou, Thomas; Wang, Wei-Gang; Chen, Christopher S; Reich, Daniel H

2013-01-28

423

Phenotype Modulation in Vascular Tissue Engineering Using Biochemical and Mechanical Stimulation  

Microsoft Academic Search

Biochemical stimulation was applied in combination with cyclic mechanical strain to engineered vascular constructs made of isolated smooth muscle cells in a three-dimensional (3D) collagen type I matrix. Platelet-derived growth factor (PDGF) and transforming growth factor beta (TGF-ß) were added exogenously to the medium used to culture the constructs. Mechanical stimulation was applied using a bioreactor system that imparted a

Jan P. Stegemann; Robert M. Nerem

2003-01-01

424

Observation of Flow Characteristics in a Model I.C. Engine Cylinder.  

National Technical Information Service (NTIS)

A study of fluid mechanical effects on unburned hydrocarbon generation was made in a single compression expansion model automobile engine. Full optical access allowed the color Schlieren observations of various gas motion alongside the engine cylinder. Mo...

N. Ishikawa J. W. Daily

1978-01-01

425

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

ERIC Educational Resources Information Center

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;…

Hamlin, Larry

426

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

ERIC Educational Resources Information Center

|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…

Bacon, E. Miles

427

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

SciTech Connect

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.

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

1987-01-01

428

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

ERIC Educational Resources Information Center

|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;…

Rains, Larry

429

Cam Design Projects in an Advanced CAD Course for Mechanical Engineers  

ERIC Educational Resources Information Center

|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…

Ault, H. K.

2009-01-01

430

Systems engineering of the Thirty Meter Telescope through integrated opto-mechanical analysis  

Microsoft Academic Search

The merit function routine (MFR) is implemented in the National Research Council Canada Integrated Modeling (NRCIM) toolset and based in the MATLAB numerical computing environment. It links ANSYS finite element structural models with ZEMAX optical models to provide a powerful integrated opto-mechanical engineering tool. The MFR is utilized by the Thirty Meter Telescope Project to assess the telescope active optics

Scott Roberts

2010-01-01

431

Evaluation of Teaching and Learning Processes in a Computer-Supported Mechanical Engineering Course.  

ERIC Educational Resources Information Center

Evaluates the teaching and learning processes in a computer-supported first-year undergraduate course in the Department of Mechanical Engineering at the University of Surrey (England). Students saw the workshop delivery as being more interesting, effective, and efficient than lecture-based delivery; help from the tutor was seen as the most…

Brown, Alan

1995-01-01

432

Effect of mechanical factors on the function of engineered human blood microvessels in microfluidic collagen gels  

Microsoft Academic Search

This work examines how mechanical signals affect the barrier function and stability of engineered human microvessels in microfluidic type I collagen gels. Constructs that were exposed to chronic low flow displayed high permeabilities to bovine serum albumin and 10 kDa dextran, numerous focal leaks, low size selectivity, and short lifespan of less than one week. Higher flows promoted barrier function and

Gavrielle M. Price; Keith H. K. Wong; James G. Truslow; Alexander D. Leung; Chitrangada Acharya; Joe Tien

2010-01-01

433

A mechanism for the needle crystal formation from magnesium detergents in engine oils  

Microsoft Academic Search

Engine oils are always formulated with overbased metallic detergents to neutralize acid and to prevent the deposition of degraded products. Among the detergents, overbased magnesium detergents sometimes form needle crystals. From research on the mechanism of needle crystal formation, we found a significant effect of water content and carbonic acid gas content in oil, and the type of magnesium detergents.

Noriyuki Naganuma; Gen Ogino; Takashi Kikuchi; Kenyu Akiyama

1996-01-01

434

What makes the Difference between Unsuccessful and Successful Firms in the German Mechanical Engineering Industry?  

Microsoft Academic Search

Against a background of rising costs and increasing competition, it is besoming more and more difficult for the small and medium-sized firms of the German mechanical engineering industry to be economically successful. The thesis that rapidly changing markets, products and production processes cause serious economic problems for these firms is, however, a proposition on an average trend. A substantial number

Ulrich Widmaier; Hiltrud Niggemann; Joachim Merz

1994-01-01

435

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

ERIC Educational Resources Information Center

|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…

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

2009-01-01

436

WAS BABBAGE’S ANALYTICAL ENGINE INTENDED TO BE A MECHANICAL MODEL OF THE MIND?  

Microsoft Academic Search

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

Christopher D. Green

2005-01-01

437

The 2004 Benjamin Franklin Medal in Mechanical Engineering presented to Roger Bacon  

Microsoft Academic Search

The Franklin Institute, Philadelphia, PA, awarded the 2004 Benjamin Franklin Medal in Mechanical Engineering to Roger Bacon for his fundamental research on the production of graphite whiskers and the determination of their microstructure and properties, for his pioneering development efforts in the production of the world's first continuously processed carbon fibers and the world's first high modulus and high-strength carbon

Brian J. Sullivan

2005-01-01

438

Education Reform Model at Faculty of Mechanical Engineering, Universiti Malaysia Pahang  

Microsoft Academic Search

This paper presents the implementation of education reform model namely outcome-based education (OBE) in terms of course delivery, assessment, evaluation and continuous quality improvement (CQI) at the Faculty of Mechanical Engineering, Universiti Malaysia Pahang (UMP). It was formalized based on the quality management system principle which is formulated its philosophy on OBE as well as on teaching and learning to

M. M. Noor; K. Kadirgama; M. M. Rahman; M. R. M. Rejab; Rosli A. Bakar; Abdullah Ibrahim

2009-01-01

439

A reflection mechanism for aft fan tone noise from turbofan engines  

Microsoft Academic Search

A fan tone noise mechanism is proposed which results from reflections from the fan of forward propagating rotor wake\\/fan exit guide vane interaction tone noise. These fan noise tones are often more dominant out of the rear than out of the front of an engine. To simulate this effect a simple qualitative prediction model was formulated and a scaled model

D. A. Topol; S. C. Holhubner; D. C. Mathews

1987-01-01

440

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

ERIC Educational Resources Information Center

|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…

Rains, Larry

441

A Video game for teaching Dynamic Systems & Control to mechanical engineering undergraduates  

Microsoft Academic Search

Dynamic Systems & Control is one of the most difficult courses to teach in the mechanical engineering curriculum. The subject is very mathematical and the mathematical framework is unfamiliar to novice students. Recently we began using a video game to demonstrate and teach content of the course. The game provides a natural way to align instruction with constructivist theories on

B. D. Coller

2010-01-01

442

Receptor-mediated mechanism for the transport of prolactin from blood to cerebrospinal fluid  

SciTech Connect

Prolactin (PRL) interacts with areas of the central nervous system which reside behind the blood-brain barrier. While vascular PRL does not cross this barrier, it is readily accessible to the cerebrospinal fluid (CSF) from which it may gain access to the PRL-responsive areas of the brain. Studies were undertaken to characterize the mechanism responsible for the translocation of PRL from blood to CSF. Rats were given external jugular vein injections of (/sup 125/-I)iodo-PRL in the presence or absence of an excess of unlabeled ovine PRL (oPRL), human GH, bovine GH, or porcine insulin. CSF and choroid plexus were removed 60 min later. CSF samples were electrophoresed on sodium dodecyl sulfate-polyacrylamide slab gels and resultant autoradiographs were analyzed with quantitative microdensitometry. The data revealed that unlabeled lactogenic hormones, viz. oPRL and human GH, caused a statistically significant inhibition of (/sup 125/I)iodo-PRL transport from blood to CSF. In contrast, nonlactogenic hormones, viz bovine GH and insulin, had no effect on (/sup 125/I)iodo-PRL transport into the CSF. An identical pattern of competition was observed in the binding of hormone to the choroid plexus. Furthermore, vascular injections of (/sup 125/I)iodo-PRL administered with a range of concentrations of unlabeled oPRL revealed a dose-response inhibition in the transport of (/sup 125/I)iodo-PRL from blood to CSF. The study demonstrates that PRL enters the CSF by a specific, PRL receptor-mediated transport mechanism. The data is consistent with the hypothesis that the transport mechanism resides at the choroid plexus. The existence of this transport mechanism reflects the importance of the cerebroventricular system in PRL-brain interactions.

Walsh, R.J.; Slaby, F.J.; Posner, B.I.

1987-05-01

443

Mechanisms controlling the volume of pleural fluid and extravascular lung water  

Microsoft Academic Search

Pleural and interstitial lung fluid volumes are strictly controlled and maintained at the minimum thanks to the ability of lymphatics to match the increase in filtration rate. In the pleural cavity, fluid accumulation is easily accommodated by retraction of lung and chest wall (high compliance of the pleural space); the increase of lymph flow per unit increase in pleural fluid

G. Miserocchi; Universitadi Milano-Bicocca

2009-01-01

444

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

PubMed

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

Nagel, Thomas; Kelly, Daniel J

2011-09-07

445

14 CFR 25.1182 - Nacelle areas behind firewalls, and engine pod attaching structures containing flammable fluid...  

Code of Federal Regulations, 2013 CFR

...attaching structures containing flammable fluid lines. 25.1182 Section 25.1182...attaching structures containing flammable fluid lines. (a) Each nacelle area immediately...attaching structure containing flammable fluid lines, must meet each requirement...

2013-01-01

446

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

NASA Astrophysics Data System (ADS)

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

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

1992-07-01

447

Combustion Chambers for Natural Gas SI Engines Part I: Fluid Flowand Combustion  

Microsoft Academic Search

The most economical way to convert truck and bus DI-diesel engines\\u000d\\u000a\\u0009to natural gas operation is to replace the injector with a spark\\u000d\\u000a\\u0009plug and modify the combustion chamber in the piston crown for spark\\u000d\\u000a\\u0009ignition operation. The modification of the piston crown should give\\u000d\\u000a\\u0009a geometry well suited for spark ignition operation with the original\\u000d\\u000a\\u0009swirling inlet port.\\u000d\\u000a\\u0009\\u000d\\u000a\\u0009\\u000d\\u000a\\u0009Ten

Bengt Johansson; Krister Olsson

1995-01-01

448

The physical vulnerability of elements at risk: a methodology based on fluid and classical mechanics  

NASA Astrophysics Data System (ADS)

The impacts of the flood events occurred in autumn 2011 in the Italian regions Liguria and Tuscany revived the engagement of the public decision makers to enhance in synergy flood control and land use planning. In this context, the design of efficient flood risk mitigation strategies and their subsequent implementation critically relies on a careful vulnerability analysis of both, the immobile and mobile elements at risk potentially exposed to flood hazards. Based on fluid and classical mechanics notions we developed computation schemes enabling for a dynamic vulnerability and risk analysis facing a broad typological variety of elements at risk. The methodological skeleton consists of (1) hydrodynamic computation of the time-varying flood intensities resulting for each element at risk in a succession of loading configurations; (2) modelling the mechanical response of the impacted elements through static, elasto-static and dynamic analyses; (3) characterising the mechanical response through proper structural damage variables and (4) economic valuation of the expected losses as a function of the quantified damage variables. From a computational perspective we coupled the description of the hydrodynamic flow behaviour and the induced structural modifications of the elements at risk exposed. Valuation methods, suitable to support a correct mapping from the value domains of the physical damage variables to the economic loss values are discussed. In such a way we target to complement from a methodological perspective the existing, mainly empirical, vulnerability and risk assessment approaches to refine the conceptual framework of the cost-benefit analysis. Moreover, we aim to support the design of effective flood risk mitigation strategies by diminishing the main criticalities within the systems prone to flood risk.

Mazzorana, B.; Fuchs, S.; Levaggi, L.

2012-04-01

449

Numerical investigation of dewatering and fluid pressure in the western Nankai subduction zone: Implications for fluid flow and mechanical behavior of the subduction thrust  

NASA Astrophysics Data System (ADS)

Excess pore water pressure is one of crucial factors that controls the nature and physical property of the plate boundary and, thus, the updip limit of the seismogenic zone. Variation of sediment composition and lithostratigraphy are key players for the spatial distribution and magnitude of fluid pressures. To investigate their impact we chose the underthrust sequence of the western Nankai subduction zone offshore Japan for our study. Sand layers characterize the incoming sediment sequence at the western Nankai margin with a total thickness of up to >200 m within a matrix of hemipelagic mud. We use a coupled loading and diffusion model that allows continuous sediment deformation. To investigate the impact of sand layers on fluid flow and fluid pressures hydrogeological properties are updated in the models based on new laboratory reference data of clays and sands from the Nankai margin area. The simulations demonstrate that ~79-89% of the incoming pore water in the underthrust sediment may be expelled by lateral fluid flow along the sands, which are at least partially cycled back to the ocean. Different deformation behavior of sands and clays enhances the effective sand permeability to be 5-24 times higher than the matrix sediment. The average pore pressure ratio along the base of the accretionary prism is lower than along the central Nankai margin where sand layers are absent. This result emphasizes that sediment lithostratigraphy is a key player for the along-strike variation in mechanical strength of the subduction thrust. The numerical study also suggests that lateral fluid flow mediates the distribution of effective stress in the underthrusting sediments, and may cause downstepping of the décollement ~20-30 km landward of the trench (as observed in seismic reflection profiles) and initiates underplating in the Nankai subduction zone.

Huepers, Andre; Saffer, Demian M.; Kopf, Achim J.

2013-04-01

450

Mechanical engineering note - safety analysis of molten uranium/water interaction in the uranium foundry furnace  

SciTech Connect

This Engineering Note describes the development of the accident criteria used the basis for the design of the uranium foundry vacuum vessel. The results of this analysis provide input into other safety notes that investigate how well the uranium containment boundary will maintain its integrity during the design basis accident. The preventative measures that have been designed into the system to minimize the potential to produce a flammable gas mixture are described. The system response is designed for consistency with applicable sections of the LLNL Health and Safety Manual, as well as the Mechanical engineering Safety Design Standards.

Gourdin, W H; Sze, J

1999-08-19

451

P1D-7 Ultrasonic Measurement Systems of Mechanical Properties for Tissue-Engineered Vessel Wall Evaluation  

Microsoft Academic Search

Evaluations for biocompatibility and structural integrity of the tissue-engineered vessel wall before and after grafting it are important. These are closely related with mechanical properties. Therefore, in vitro and in vivo ultrasonic measurement systems for tissue-engineered vessel wall evaluation was developed based on the ultrasonic elasticity measurement method suited to the evaluation of mechanical properties, in this study. Based on

Naotaka Nitta; Takashi Yamane; T. Shin'oka; T. Shiina

2006-01-01

452

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

Microsoft Academic Search

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

S. K. Chakrabarti; H. Maeda; C. Aage; F. G. Nielsen

1990-01-01

453

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

PubMed

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