WorldWideScience

Sample records for apodized rectangular pistons

  1. Pistonics

    DEFF Research Database (Denmark)

    Perram, John W.; Præstgaard, Eigil; Smith, Edgar R.

    2011-01-01

    By arguing that the expression 3PV/2 for the kinetic energy of an ideal gas is its internal energy function, we avoid the standard appeal to an equipartition theorem and, by analysing the Carnot cycle for a cylinder of gas enclosed by a piston, we show that the Kelvin temperature of an ideal gas...

  2. Piston rod seal

    Energy Technology Data Exchange (ETDEWEB)

    Lindskoug, S.

    1984-06-05

    In a piston rod seal of the type comprising a gland through which the piston rod is passed the piston is provided with a sleeve surrounding the piston rod and extending axially so as to axially partly overlap the gland when the piston is in its bottom dead center position. 4 figs.

  3. Piston rod seal

    Energy Technology Data Exchange (ETDEWEB)

    Lindskoug, Stefan (Malmo, SE)

    1984-01-01

    In a piston rod seal of the type comprising a gland through which the piston rod is passed the piston is provided with a sleeve surrounding the piston rod and extending axially so as to axially partly overlap the gland when the piston is in its bottom dead center position.

  4. 49 CFR 230.93 - Pistons and piston rods.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Pistons and piston rods. 230.93 Section 230.93... Tenders Driving Gear § 230.93 Pistons and piston rods. (a) Maintenance and testing. Pistons and piston rods shall be maintained in safe and suitable condition for service. Piston rods shall be inspected...

  5. Piston and connecting rod assembly

    Science.gov (United States)

    Brogdon, James William (Inventor); Gill, David Keith (Inventor); Chatten, John K. (Inventor)

    2001-01-01

    A piston and connecting rod assembly includes a piston crown, a piston skirt, a connecting rod, and a bearing insert. The piston skirt is a component separate from the piston crown and is connected to the piston crown to provide a piston body. The bearing insert is a component separate from the piston crown and the piston skirt and is fixedly disposed within the piston body. A bearing surface of a connecting rod contacts the bearing insert to thereby movably associate the connecting rod and the piston body.

  6. Special Apodized Fiber Bragg Grating for Flat-top Band-pass Reflectivity Filter

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-min; YU Zhong-yuan; YANG Hong-bo; YANG Bo-jun; YU Li; ZHANG Xiao-guang

    2004-01-01

    The characteristics of special apodized fiber Bragg grating (FBG) in flat-top pass-band as reflectivity filter are presented. This special apodized FBG was designed by the particle swarm optimization algorithm. Compared with conventional apodized FBG, the special apodized FBG presented was more robust in the flat-top pass-band characteristic even if the strength of grating is very week. This technology is very interesting in designing the filter for wavelength division multiplexing system.

  7. Cooled spool piston compressor

    Science.gov (United States)

    Morris, Brian G. (Inventor)

    1993-01-01

    A hydraulically powered gas compressor receives low pressure gas and outputs a high pressure gas. The housing of the compressor defines a cylinder with a center chamber having a cross-sectional area less than the cross-sectional area of a left end chamber and a right end chamber, and a spool-type piston assembly is movable within the cylinder and includes a left end closure, a right end closure, and a center body that are in sealing engagement with the respective cylinder walls as the piston reciprocates. First and second annual compression chambers are provided between the piston enclosures and center housing portion of the compressor, thereby minimizing the spacing between the core gas and a cooled surface of the compressor. Restricted flow passageways are provided in the piston closure members and a path is provided in the central body of the piston assembly, such that hydraulic fluid flows through the piston assembly to cool the piston assembly during its operation. The compressor of the present invention may be easily adapted for a particular application, and is capable of generating high gas pressures while maintaining both the compressed gas and the compressor components within acceptable temperature limits.

  8. Apodized RFI filtering of synthetic aperture radar images

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2014-02-01

    Fine resolution Synthetic Aperture Radar (SAR) systems necessarily require wide bandwidths that often overlap spectrum utilized by other wireless services. These other emitters pose a source of Radio Frequency Interference (RFI) to the SAR echo signals that degrades SAR image quality. Filtering, or excising, the offending spectral contaminants will mitigate the interference, but at a cost of often degrading the SAR image in other ways, notably by raising offensive sidelobe levels. This report proposes borrowing an idea from nonlinear sidelobe apodization techniques to suppress interference without the attendant increase in sidelobe levels. The simple post-processing technique is termed Apodized RFI Filtering (ARF).

  9. 3-D Imaging Using Row–Column-Addressed Arrays With Integrated Apodization. Part I: Apodization Design and Line Element Beamforming

    DEFF Research Database (Denmark)

    Rasmussen, Morten Fischer; Christiansen, Thomas Lehrmann; Thomsen, Erik Vilain;

    2015-01-01

    ghost echo intensity of a scatterer at (x,y, z) = (8, 3, 30) mm was decreased by 43 dB by integrating roll-off apodization into the array. The main lobe was unaffected by the apodization. Simulations of a 3-mm-diameter anechoic blood vessel at 30 mm depth showed that applying the transducer......-integrated apodization increased the apparent diameter of the vessel from 2.0 mm to 2.4 mm, corresponding to an increase from 67% to 80% of the true vessel diameter. The line element beamforming approach is shown to be essential for achieving correct time-of-flight calculations, and hence avoid geometrical distortions...

  10. Finite-temperature Casimir effect in piston geometry and its classical limit

    Energy Technology Data Exchange (ETDEWEB)

    Lim, S.C. [Multimedia University, Faculty of Engineering, Cyberjaya, Selangor Darul Ehsan (Malaysia); Teo, L.P. [Multimedia University, Faculty of Information Technology, Cyberjaya, Selangor Darul Ehsan (Malaysia)

    2009-03-15

    We consider the Casimir force acting on a d-dimensional rectangular piston due to a massless scalar field with periodic, Dirichlet and Neumann boundary conditions and an electromagnetic field with perfect electric-conductor and perfect magnetic-conductor boundary conditions. The Casimir energy in a rectangular cavity is derived using the cut-off method. It is shown that the divergent part of the Casimir energy does not contribute to the Casimir force acting on the piston, thus renders an unambiguously defined Casimir force acting on the piston. At any temperature, it is found that the Casimir force acting on the piston increases from -{infinity} to 0 when the separation a between the piston and the opposite wall increases from 0 to {infinity}. This implies that the Casimir force is always an attractive force pulling the piston towards the closer wall, and the magnitude of the force gets larger as the separation a gets smaller. Explicit exact expressions for the Casimir force for small and large plate separations and for low and high temperatures are computed. The limits of the Casimir force acting on the piston when some pairs of transversal plates are large are also derived. An interesting result regarding the influence of temperature is that in contrast to the conventional result that the leading term of the Casimir force acting on a wall of a rectangular cavity at high temperature is the Stefan-Boltzmann (or black-body radiation) term which is of order T {sup d+1}, it is found that the contributions of this term from the two regions separating the piston cancel with each other in the case of piston. The high-temperature leading-order term of the Casimir force acting on the piston is of order T, which shows that the Casimir force has a nontrivial classical {Dirac_h}{yields}0 limit. Explicit formulas for the classical limit are computed. (orig.)

  11. Apodization in high-contrast long-slit spectroscopy

    CERN Document Server

    Vigan, A; Dohlen, K

    2013-01-01

    The spectroscopy of faint planetary-mass companions to nearby stars is one of the main challenges that new-generation high-contrast spectro-imagers are going to face. In a previous work we presented a long slit coronagraph (LSC), for which the presence of a slit in the coronagraphic focal plane induces a complex distribution of energy in the Lyot pupil-plane that cannot be easily masked with a binary Lyot stop. To alleviate this concern, we propose to use a pupil apodization to suppress diffraction, creating an apodized long slit coronagraph (ALSC). After describing how the apodization is optimized, we demonstrate its advantages with respect to the CLC in the context of SPHERE/IRDIS long slit spectroscopy (LSS) mode at low-resolution with a 0.12" slit and 0.18" coronagraphic mask. We perform different sets of simulations with and without aberrations, and with and without a slit to demonstrate that the apodization is a more appropriate concept for LSS, at the expense of a significantly reduced throughput (37%)...

  12. Analysis of Piston Slap Motion

    Directory of Open Access Journals (Sweden)

    Narayan S.

    2015-05-01

    Full Text Available Piston slap is the major force contibuting towards noise levels in combustion engines.This type of noise depends upon a number of factors such as the piston-liner gap, type of lubricant used, number of piston pins as well as geometry of the piston. In this work the lateral and rotary motion of the piston in the gap between the cylinder liner and piston has been analyzed. A model that can predict the forces and response of the engine block due to slap has been dicussed. The parameters such as mass, spring and damping constant have been predicted using a vibrational mobility model.

  13. Analysis of Piston Slap Motion

    Science.gov (United States)

    Narayan, S.

    2015-05-01

    Piston slap is the major force contibuting towards noise levels in combustion engines.This type of noise depends upon a number of factors such as the piston-liner gap, type of lubricant used, number of piston pins as well as geometry of the piston. In this work the lateral and rotary motion of the piston in the gap between the cylinder liner and piston has been analyzed. A model that can predict the forces and response of the engine block due to slap has been dicussed. The parameters such as mass, spring and damping constant have been predicted using a vibrational mobility model.

  14. Spherical Casimir pistons

    CERN Document Server

    Dowker, J S

    2011-01-01

    A piston is introduced into a spherical lune Casimir cavity turning it into two adjacent lunes separated by the (hemispherical) piston. On the basis of zeta function regularisation, the vacuum energy of the arrangement is finite for conformal propagation in space-time. For even spheres this energy is independent of the angle of the lune. For odd dimensions it is shown that for all Neumann, or all Dirichlet, boundary conditions the piston is attracted or repelled by the nearest wall if d=3,7,... or if d=1,5,..., respectively. For hybrid N-D conditions these requirements are switched. If a mass is added, divergences arise which render the model suspect. The analysis, however, is relatively straightforward and involves the Barnes zeta function.

  15. Pistons and engine testing

    CERN Document Server

    2016-01-01

    The ever-increasing demands placed on combustion engines are just as great when it comes to this centerpiece—the piston. Achieving less weight or friction, or even greater wear resistance, requires in-depth knowledge of the processes taking place inside the engine, suitable materials, and appropriate design and manufacturing processes for pistons, including the necessary testing measures. It is no longer possible for professionals in automotive engineering to manage without specific expertise of this kind, whether they work in the field of design, development, testing, or maintenance. This technical book answers these questions in detail and in a very clear and comprehensible way. In this second, revised edition, every chapter has been revised and expanded. The chapter on “Engine testing”, for example, now include extensive results in the area of friction power loss measurement and lube oil consumption measurement. Contents Piston function, requirements, and types Design guidelines Simulation of the ope...

  16. Composites applied for pistons

    Directory of Open Access Journals (Sweden)

    Wieczorek J.

    2007-01-01

    Full Text Available In the article the possibility of application the composite materials in casts into metal mould to form the pistons for compressors have been presented. In cooperation with “Zlotecki” company was undertaken the test of casting in productive conditions the aluminium alloy matrix composites reinforced with silicon carbide particles and composites reinforced with the mixture of the silicon carbide (SiC and amorphous glass carbon particles. On the basis microstructural investigations were affirmed the uniformly distribution of reinforcing particles on the cross section of studied pistons. Realized technological tests confirmed the possibility of formation composite pistons with one kind of reinforcing phase and heterophase reinforcement from utilization the technology of mould casting.

  17. Pistons and engine testing

    CERN Document Server

    GmbH, Mahle

    2012-01-01

    The ever-increasing demands placed on combustion engines are just as great when it comes to this centerpiece - the piston. Achieving less weight or friction, or even greater wear resistance, requires in-depth knowledge of the processes taking place inside the engine, suitable materials, and appropriate design and machining processes for pistons, including the necessary testing measures. It is no longer possible for professionals in automotive engineering to manage without specific know-how of this kind, whether they work in the field of design, development, testing, or maintenance. This techni

  18. Piston for rod pumping

    Energy Technology Data Exchange (ETDEWEB)

    Pastushenko, G.I.

    1965-06-22

    A piston, or plunger, for rod pumping, is made up of a cylindrical housing with labryinthal seals, a nose piece, and a scraper. In order to remove paraffin from the inside surface of the production pipe, the housing is made in telescopic form. The scraper consists of an arrangement of springs installed on the outer surface of the housing.

  19. Electromagnetic piston engine

    OpenAIRE

    Божко, А. Е.; Иванов, Е. М.; ИВАНОВА З.А.

    2012-01-01

    In-process the presented features of functioning of electromagnetic reciprocator, that contains the pistons with flows, united by means of general knee axle with a fly-wheel, are accommodated in the cylinders equipped by the solenoids set in dead centers.

  20. Calculation of an optimized telescope apodizer for detection of Earth-like planets

    CERN Document Server

    Gonsalves, R

    2002-01-01

    One of two approaches to implementing NASA's Terrestrial Planet Finder is to build a space telescope that utilizes the techniques of coronagraphy and apodization to suppress diffraction and image exo-planets. We present a method for calculation of a telescope's apodizer which suppresses the side lobes of the image of a star so as to optimally detect an Earth-like planet. Given the shape of a telescope's aperture and given a search region for a detector, we solve an integral equation to determine an amplitude modulation (an apodizer) which suppresses the star's energy in the focal plane search region. The method is quite general and yields as special cases the product apodizer reported by Nisenson and Papaliolios (2001) and the Prolate spheroidal apodizer of Kasdin et al (2002), and Aime et al (2002). We show computer simulations of the apodizers and the corresponding point spread functions for various aperture-detector configurations.

  1. Acoustical tweezers using single spherically focused piston, X-cut, and Gaussian beams.

    Science.gov (United States)

    Mitri, Farid G

    2015-10-01

    Partial-wave series expansions (PWSEs) satisfying the Helmholtz equation in spherical coordinates are derived for circular spherically focused piston (i.e., apodized by a uniform velocity amplitude normal to its surface), X-cut (i.e., apodized by a velocity amplitude parallel to the axis of wave propagation), and Gaussian (i.e., apodized by a Gaussian distribution of the velocity amplitude) beams. The Rayleigh-Sommerfeld diffraction integral and the addition theorems for the Legendre and spherical wave functions are used to obtain the PWSEs assuming weakly focused beams (with focusing angle α ⩽ 20°) in the Fresnel-Kirchhoff (parabolic) approximation. In contrast with previous analytical models, the derived expressions allow computing the scattering and acoustic radiation force from a sphere of radius a without restriction to either the Rayleigh (a ≪ λ, where λ is the wavelength of the incident radiation) or the ray acoustics (a ≫λ) regimes. The analytical formulations are valid for wavelengths largely exceeding the radius of the focused acoustic radiator, when the viscosity of the surrounding fluid can be neglected, and when the sphere is translated along the axis of wave propagation. Computational results illustrate the analysis with particular emphasis on the sphere's elastic properties and the axial distance to the center of the concave surface, with close connection of the emergence of negative trapping forces. Potential applications are in single-beam acoustical tweezers, acoustic levitation, and particle manipulation. PMID:26470046

  2. Apodized Pupil Lyot Coronagraphs for Arbitrary Telescope Apertures

    CERN Document Server

    Soummer, R

    2004-01-01

    In the context of high dynamic range imaging, this study presents a breakthrough for the understanding of Apodized Pupil Lyot Coronagraphs, making them available for arbitrary aperture shapes. These new solutions find immediate application in current, ground-based coronagraphic studies (Gemini, VLT) and in existing instruments (AEOS Lyot Project). They also offer the possiblity of a search for an on-axis design for TPF. The unobstructed aperture case has already been solved by Aime et al. (2002) and Soummer et al. (2003). Analytical solutions with identical properties exist in the general case and, in particular, for centrally obscured apertures. Chromatic effects can be mitigated with a numerical optimization. The combination of analytical and numerical solutions enables the study of the complete parameter space (central obstruction, apodization throughput, mask size, bandwidth, and Lyot stop size).

  3. Strange Horizons: Teaching Usual and Unusual Atmospheric Effects using APOD

    Science.gov (United States)

    Wilson, Teresa

    2015-01-01

    Unusual Sun and moonsets are not only photogenic -- they are educational. Images appearing on the Astronomy Picture of the Day (APOD) that demonstrate dramatic examples of the green flash, the Moon illusion, Fata Morgana, and the Etruscan vase effect are discussed in terms of how they demonstrate atmospheric refraction, chromatic aberration, and temperature inversions. A lesson plan is given for undergraduate classrooms as well as estimates of how each effect might alter the perceived time of a common sunset.

  4. Multi-stage apodized pupil Lyot coronagraph experimental results

    Science.gov (United States)

    Abe, L.; Venet, M.; Enya, K.; Kataza, H.; Nakagawa, T.; Tamura, M.

    2008-07-01

    Prolate (Pupil) Apodized Lyot Coronagraphs (PPALC) are known to offer optimal performances for a Lyot-type Coronagraph configuration, i.e. with an opaque occulting focal mask. One additional benefit of PPALC is its possible use in a multi-stage configuration. In theory, the coronagraphic performance can be QN, where Q is the energy rejection factor of one stage (the first one), and N the number of stages. Several ground-based telescopes are considering PPALC as an option for their high-contrast instrumentation (e.g. Gemini/GPI, EELT/EPICS, Subaru HiCIAO). Although the PPALC suffers from several limitations, several works are currently focused on fabricating entrance pupil apodizers and trying to find ways to overcome chromatism issues. In this work, we present the first experimental results from Multi-Stage PPALC (MS-PPALC) that was done in the context of the Japanese space telescope SPICA coronagraph project. Our entrance pupil apodizers use small diameter High Energy Beam Sensitive glass (HEBS-glass) from Canyon Materials Inc. The current results show modest coronagraphic performance due to uncompensated phase aberrations inherent to HEBS-glass material. In addition, and due to these uncompensated phase aberrations, the present optical configuration is an altered version of the originally planned set-up. However, we can demonstrate the validity the MS-PPALC concept and compare it to numerical simulations.

  5. Row-Column Addressed 2-D CMUT Arrays with Integrated Apodization

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Rasmussen, Morten Fischer; Jensen, Jørgen Arendt;

    2014-01-01

    Experimental results from row-column addressed capacitive micromachined ultrasonic transducers (CMUTs) with integrated apodization are presented. The apodization is applied by varying the density of CMUT cells in the array with the objective of damping the edge waves originating from the element...... ends. Two row-column addressed 32+32 CMUT arrays are produced using a wafer-bonding technique, one with and one without integrated apodization. Hydrophone measurements of the emitted pressure field from the array with integrated apodization show a reduction in edge wave energy of 8.4 dB (85 %) compared...

  6. Spherical Casimir pistons

    Energy Technology Data Exchange (ETDEWEB)

    Dowker, J S, E-mail: dowker@man.ac.uk [Theory Group, School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom)

    2011-08-07

    A piston is introduced into a spherical lune Casimir cavity turning it into two adjacent lunes separated by the (hemispherical) piston. On the basis of zeta-function regularization, the vacuum energy of the arrangement is finite for conformal propagation in spacetime. For even spheres this energy is independent of the angle of the lune. For odd dimensions it is shown that for all Neumann, or all Dirichlet, boundary conditions the piston is repelled or attracted by the nearest wall if d = 3, 7, ... or if d = 1, 5, ... , respectively. For hybrid N-D conditions these requirements are switched. If a mass is added, divergences arise which render the model suspect. The analysis, however, is relatively straightforward and involves the Barnes zeta function. The extension to finite temperatures is made and it is shown that for the 3, 7, ... series of odd spheres, the repulsion by the walls continues but that, above a certain temperature, the free energy acquires two minima symmetrically placed about the midpoint.

  7. Delay stroke piston and rod for engine

    Energy Technology Data Exchange (ETDEWEB)

    Booher, B.V.

    1995-03-09

    A reciprocating piston internal combustion engine comprises a cylinder having opposed ends, a piston reciprocably mounted in the cylinder, a connecting rod having a crank journal end and a piston journal end, the connecting rod connected to the piston at the piston journal end by means for first and second wrist pins spaced longitudinally along the rod, the first wrist pin journaled in a bore in the piston and in a slot in the piston rod, and the second wrist pin journaled in a bore in the piston rod and a longitudinal slot in the piston. (author)

  8. 49 CFR 229.55 - Piston travel.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Piston travel. 229.55 Section 229.55... Piston travel. (a) Brake cylinder piston travel shall be sufficient to provide brake shoe clearance when... piston travel may not exceed 11/2 inches less than the total possible piston travel. The total...

  9. Comparison of a hydrophilic and a hydrophobic apodized diffractive multifocal intraocular lens.

    NARCIS (Netherlands)

    Linden, J.W.M. van der; Meulen, I.J. van der; Mourits, M.P.; Lapid-Gortzak, R.

    2013-01-01

    To compare outcomes between a new design apodized diffractive hydrophilic multifocal intraocular lens (IOL) (Seelens MF; study group), and a well-known apodized diffractive hydrophobic multifocal IOL (SN6AD1; control group). A comparative case series comparing refractive and visual outcomes at dista

  10. Ultrahigh-efficiency apodized grating coupler using fully etched photonic crystals

    DEFF Research Database (Denmark)

    Ding, Yunhong; Ou, Haiyan; Peucheret, Christophe

    2013-01-01

    We present an efficient method to design apodized grating couplers with Gaussian output profiles for efficient coupling between standard single mode fibers and silicon chips. An apodized grating coupler using fully etched photonic crystal holes on the silicon-on-insulator platform is designed...

  11. Compact implementation of dynamic receive apodization in ultrasound scanners

    DEFF Research Database (Denmark)

    Tomov, Borislav Gueorguiev; Jensen, Jørgen Arendt

    2004-01-01

    The image quality in medical ultrasound scanners is determined by several factors, one of which is the ability of the receive beamformer to change the aperture weighting function with depth and beam angle. In digital beamformers, precise dynamic apodization can be achieved by representing the fun...... operate at 129.82 MHz and occupies 1.28 million gates. Simulated in Matlab, a 64-channel beamformer provides gray scale image with around 55 dB dynamic range. The beamformed data can also be used for flow estimation....

  12. Casimir Piston of Real Materials and its Application to Multi-Layer Models

    CERN Document Server

    Teo, L P

    2009-01-01

    In this article, we derive the formula for the Casimir force acting on a piston made of real material moving inside a perfectly conducting rectangular box. It is shown that by taking suitable limits, one recovers the formula for the Casimir force acting on a perfectly conducting piston or an infinitely permeable piston. Lipshitz formula for finite temperature Casimir force acting on parallel plates made of real materials is re-derived by considering the five-layer model in the context of piston approach. It is observed that the divergences of the Casimir force will only cancel under certain conditions, for example, when the regions separated by the plates are filled with isorefractive media.

  13. Apodized grating coupler using fully-etched nanostructures

    Science.gov (United States)

    Wu, Hua; Li, Chong; Li, Zhi-Yong; Guo, Xia

    2016-08-01

    A two-dimensional apodized grating coupler for interfacing between single-mode fiber and photonic circuit is demonstrated in order to bridge the mode gap between the grating coupler and optical fiber. The grating grooves of the grating couplers are realized by columns of fully etched nanostructures, which are utilized to digitally tailor the effective refractive index of each groove in order to obtain the Gaussian-like output diffractive mode and then enhance the coupling efficiency. Compared with that of the uniform grating coupler, the coupling efficiency of the apodized grating coupler is increased by 4.3% and 5.7%, respectively, for the nanoholes and nanorectangles as refractive index tunes layer. Project supported by the National Natural Science Foundation of China (Grant Nos. 61222501, 61335004, and 61505003), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20111103110019), the Postdoctoral Science Foundation of Beijing Funded Project, China (Grant No. Q6002012201502), and the Science and Technology Research Project of Jiangxi Provincial Education Department, China (Grant No. GJJ150998).

  14. Apodized grating coupler using fully-etched nanostructures

    Science.gov (United States)

    Wu, Hua; Li, Chong; Li, Zhi-Yong; Guo, Xia

    2016-08-01

    A two-dimensional apodized grating coupler for interfacing between single-mode fiber and photonic circuit is demonstrated in order to bridge the mode gap between the grating coupler and optical fiber. The grating grooves of the grating couplers are realized by columns of fully etched nanostructures, which are utilized to digitally tailor the effective refractive index of each groove in order to obtain the Gaussian-like output diffractive mode and then enhance the coupling efficiency. Compared with that of the uniform grating coupler, the coupling efficiency of the apodized grating coupler is increased by 4.3% and 5.7%, respectively, for the nanoholes and nanorectangles as refractive index tunes layer. Project supported by the National Natural Science Foundation of China (Grant Nos. 61222501, 61335004, and 61505003), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20111103110019), the Postdoctoral Science Foundation of Beijing Funded Project, China (Grant No. Q6002012201502), and the Science and Technology Research Project of Jiangxi Provincial Education Department, China (Grant No. GJJ150998).

  15. 49 CFR 230.76 - Piston travel.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Piston travel. 230.76 Section 230.76... Tenders Brake and Signal Equipment § 230.76 Piston travel. (a) Minimum piston travel. The minimum piston travel shall be sufficient to provide proper brake shoe clearance when the brakes are released....

  16. A Delta-Sigma beamformer with integrated apodization

    DEFF Research Database (Denmark)

    Tomov, Borislav Gueorguiev; Stuart, Matthias Bo; Hemmsen, Martin Christian;

    2013-01-01

    This paper presents a new design of a discrete time Delta-Sigma (ΔΣ) oversampled ultrasound beamformer which integrates individual channel apodization by means of variable feedback voltage in the Delta-Sigma analog to digital (A/D) converters. The output bit-width of each oversampled A/D converter...... remains the same as in an unmodified one. The outputs of all receiving channels are delayed and summed, and the resulting multi-bit sample stream is filtered and decimated to become an image line. The simplicity of this beamformer allows the production of high-channel-count or very compact beamformers...... suitable for 2-D arrays or compact portable scanners. The new design is evaluated using measured data from the research scanner SARUS and a BK-8811 192 element linear array transducer (BK Medical, Herlev, Denmark), insonifying a water-filled wire phantom containing four wires orthogonal to the image plane...

  17. Apodized vortex coronagraph designs for segmented aperture telescopes

    CERN Document Server

    Ruane, Garreth; Mawet, Dimitri; Pueyo, Laurent; Shaklan, Stuart

    2016-01-01

    Current state-of-the-art high contrast imaging instruments take advantage of a number of elegant coronagraph designs to suppress starlight and image nearby faint objects, such as exoplanets and circumstellar disks. The ideal performance and complexity of the optical systems depends strongly on the shape of the telescope aperture. Unfortunately, large primary mirrors tend to be segmented and have various obstructions, which limit the performance of most conventional coronagraph designs. We present a new family of vortex coronagraphs with numerically-optimized gray-scale apodizers that provide the sensitivity needed to directly image faint exoplanets with large, segmented aperture telescopes, including the Thirty Meter Telescope (TMT) as well as potential next-generation space telescopes.

  18. Integral Ring Carbon-Carbon Piston

    Science.gov (United States)

    Northam, G. Burton (Inventor)

    1999-01-01

    An improved structure for a reciprocating internal combustion engine or compressor piston fabricate from carbon-carbon composite materials is disclosed. An integral ring carbon-carbon composite piston, disclosed herein, reduces the need for piston rings and for small clearances by providing a small flexible, integral component around the piston that allows for variation in clearance due to manufacturing tolerances, distortion due to pressure and thermal loads, and variations in thermal expansion differences between the piston and cylinder liner.

  19. An Apodized Kepler Periodogram for Separating Planetary and Stellar Activity Signals

    CERN Document Server

    Gregory, Philip C

    2016-01-01

    A new apodized Keplerian (AK) model is proposed for the analysis of precision radial velocity (RV) data to model both planetary and stellar activity (SA) induced RV signals. A symmetrical Gaussian apodization function with unknown width and center can distinguish planetary signals from SA signals on the basis of the span of the apodization window. The general model for $m$ apodized Keplerian signals includes a linear regression term between RV and the stellar activity diagnostic $\\log(R'hk)$, as well as an extra Gaussian noise term with unknown standard deviation. The model parameters are explored using a Bayesian fusion MCMC code. A differential version of the Generalized Lomb-Scargle periodogram that employs a control diagnostic provides an additional way of distinguishing SA signals and helps guide the choice of new periods. Results are reported for a recent international RV blind challenge which included multiple state of the art simulated data sets supported by a variety of stellar activity diagnostics. ...

  20. Simulation of an apodizer's effect for high-density optical storage

    Institute of Scientific and Technical Information of China (English)

    Xiumin Gao; Wendong Xu; Fuxi Gan

    2005-01-01

    @@ The effect of an apodizer with two parallel taper refractive surfaces is theoretically investigated for highdensity optical storage. The apodizer may modulate an incident Gaussian beam into an annular beam. Simulation shows that with the increasing inner radius of the modulated beam, the focal spot shrinks obviously. The depolarization effect gets strong simultaneously, which induces the circular symmetry loss of the focal spot. In this process, pattern density of the orthogonal and longitudinal diffractive fields increases remarkably.

  1. Properties of length-apodized phase-shifted lpgs operating at the phase matching turning point

    OpenAIRE

    James, Stephen W.; Topliss, Stephen M.; Tatam, Ralph P.

    2012-01-01

    The characteristics of length-apodized phase-shifted fiber optic long period gratings with full and partial nanostructured coatings have been explored theoretically and experimentally. The twin rejection bands that are characteristic of length-apodized phase-shifted long period gratings are studied for a long period grating (LPG) operating at the phase matching turning point. When one half of the length of the LPG is coated, complex bandgap like structure appears within the ...

  2. Analysing the effects of apodizing windows on local correlation tracking using Nirvana simulations of convection

    OpenAIRE

    Louis, Rohan E.; Ravindra, B.; Manolis K. Georgoulis; Küker, Manfred

    2015-01-01

    We employ different shapes of apodizing windows in the local correlation tracking (LCT) routine to retrieve horizontal velocities using numerical simulations of convection. LCT was applied on a time sequence of temperature maps generated by the Nirvana code with four different apodizing windows, namely--Gaussian, Lorentzian, trapezoidal and triangular, with varying widths. In terms of correlations (between the LCT-retrieved and simulated flow field), the triangular and the trapezoidal perform...

  3. PIZZA: a phase-induced zonal Zernike apodization designed for stellar coronagraphy

    Science.gov (United States)

    Martinache, Frantz

    2004-08-01

    I explore here the possibilities offered by the general formalism of coronagraphy for the very special case of phase contrast. This technique, invented by Zernike, is commonly used in microscopy, to see phase objects such as micro-organisms, and in strioscopy, to control the quality of optics polishing. It may find application in telescope pupil apodization with significant advantages over classical pupil apodization techniques, including high throughput and no off-axis resolution loss, which is essential for exoplanet imaging.

  4. Design of Piston Ring Friction Tester Apparatus

    DEFF Research Database (Denmark)

    Klit, Peder

    2006-01-01

    the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external load may be established by measuring the pressure distribution, i.e. the pressure drop in the piston ring package. Speed and temperature may also be established. The amount...... and forces on piston rod. Since the frictional forces are small compared to the rest of the acting forces the main design idea is to fix the piston, while the cylinder liner moves. This approach makes it simple to measure the parameters mentioned above by putting the instrumentation in the piston....

  5. Cooling of rectangular bars

    International Nuclear Information System (INIS)

    A solution of the time-transient Heat Transfer Differential Equation in rectangular coordinates is presented, leading to a model which describes the temperature drop with time in rectangular bars. It is similar to an other model for cilindrical bars which has been previously developed in the Laboratory of Mechanical Metallurgy of UFRGS. Following these models, a generalization has been made, which permits cooling time evaluation for all profiles. These results are compared with experimental laboratory data in the 1200 to 8000C range. Some other existing models were also studied which have the purpose of studing the same phenomenon. Their mathematical forms and their evaluated values are analyzed and compared with experimental ones. (Author)

  6. Piston-assisted charge pumping

    CERN Document Server

    Kaur, D; Mourokh, L

    2015-01-01

    We examine charge transport through a system of three sites connected in series in the situation when an oscillating charged piston modulates the energy of the middle site. We show that with an appropriate set of parameters, charge can be transferred against an applied voltage. In this scenario, when the oscillating piston shifts away from the middle site, the energy of the site decreases and it is populated by a charge transferred from the lower energy site. On the other hand, when the piston returns to close proximity, the energy of the middle site increases and it is depopulated by the higher energy site. Thus through this process, the charge is pumped against the potential gradient. Our results can explain the process of proton pumping in one of the mitochondrial enzymes, Complex I. Moreover, this mechanism can be used for electron pumping in semiconductor nanostructures.

  7. Performance characterization of a broadband vector Apodizing Phase Plate coronagraph

    CERN Document Server

    Otten, G P P L; Kenworthy, M A; Miskiewicz, M N; Escuti, M J

    2014-01-01

    One of the main challenges for the direct imaging of planets around nearby stars is the suppression of the diffracted halo from the primary star. Coronagraphs are angular filters that suppress this diffracted halo. The Apodizing Phase Plate coronagraph modifies the pupil-plane phase with an anti-symmetric pattern to suppress diffraction over a 180 degree region from 2 to 7 {\\lambda}/D and achieves a mean raw contrast of 10^-4 in this area, independent of the tip-tilt stability of the system. Current APP coronagraphs implemented using classical phase techniques are limited in bandwidth and suppression region geometry (i.e. only on 1 side of the star). In this paper, we show the vector-APP (vAPP) whose phase pattern is implemented by the orientation of patterned liquid crystals. Beam-splitting according to circular polarization states produces two, complementary PSFs with dark holes on either side. We have developed a prototype vAPP that consists of a stack of 3 twisting liquid crystal layers with a bandwidth o...

  8. Improved achromatization of phase mask coronagraphs using colored apodization

    CERN Document Server

    N'Diaye, M; Cuevas, S; Soummer, R; Sánchez-Pérez, C; Zamkotsian, F

    2011-01-01

    For direct imaging of exoplanets, a stellar coronagraph helps to remove the image of an observed bright star by attenuating the diffraction effects caused by the telescope aperture of diameter D. The Dual Zone Phase Mask (DZPM) coronagraph constitutes a promising concept since it theoretically offers a small inner working angle (IWA \\sim \\lambda_0/D), good achromaticity and high starlight rejection, typically reaching a 1e6 contrast at 5 \\lambda_0/D from the star over a spectral bandwidth \\Delta\\lambda/\\lambda_0 of 25% (similar to H-band). This last value proves to be encouraging for broadband imaging of young and warm Jupiter-like planets. Contrast levels higher than 1e6 are however required for the observation of older and/or less massive companions over a finite spectral bandwidth. An achromatization improvement of the DZPM coronagraph is therefore mandatory to reach such performance. In its design, the DZPM coronagraph uses a grey (or achromatic) apodization. We propose to replace it by a colored apodizat...

  9. Linear Motor Free Piston Compressor

    Science.gov (United States)

    Bloomfield, David P.

    1995-02-01

    A Linear Motor Free Piston Compressor (LMFPC), a free piston pressure recovery system for fuel cell powerplants was developed. The LMFPC consists of a reciprocating compressor and a reciprocating expander which are separated by a piston. In the past energy efficient turbochargers have been used for pressure large (over 50 kW) fuel cell powerplants by recovering pressure energy from the powerplant exhaust. A free piston compressor allows pressurizing 3 - 5 kW sized fuel cell powerplants. The motivation for pressurizing PEM fuel cell powerplants is to improve fuel cell performance. Pressurization of direct methanol fuel cells will be required if PEM membranes are to be used Direct methanol oxidation anode catalysts require high temperatures to operate at reasonable power densities. The elevated temperatures above 80 C will cause high water loss from conventional PEM membranes unless pressurization is employed. Because pressurization is an energy intensive process, recovery of the pressure energy is required to permit high efficiency in fuel cell powerplants. A complete LMFPC which can pressurize a 3 kW fuel cell stack was built. This unit is one of several that were constructed during the course of the program.

  10. Improved extension of depth-of-field performance by apodized wavefront coding

    Science.gov (United States)

    Tsukasaki, Takafumi; Komatsu, Shinchi

    2016-08-01

    Wavefront coding (WFC) is a popular technique for extending the depth of field (DOF), where the DOF is extended by the phase modulation of the pupil function using a phase mask and digital processing using a deconvolution filter. We previously proposed an apodized WFC system with a Gaussian aperture that extends the DOF while suppressing artifacts in the reconstructed image. In this study, the influence of aberrations on the proposed WFC system was examined in detail by computer simulation. Then, the image quality was experimentally examined to confirm the effectiveness of the apodized WFC system. In addition, we proposed a new type of aperture, i.e., a generalized Gaussian aperture, to prevent the significant reduction in transmitted light intensity due to apodization, the effectiveness of which was confirmed by computer simulation.

  11. 3-D Imaging Using Row-Column-Addressed Arrays With Integrated Apodization

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Rasmussen, Morten Fischer; Bagge, Jan Peter;

    2015-01-01

    This paper demonstrates the fabrication, characterization, and experimental imaging results of a 62+62 element λ/2-pitch row-column-addressed capacitive micromachined ultrasonic transducer (CMUT) array with integrated apodization. A new fabrication process was used to manufacture a 26.3 mm by 26.......3 mm array using five lithography steps. The array includes an integrated apodization, presented in detail in Part I of this paper, which is designed to reduce the amplitude of the ghost echoes that are otherwise prominent for row-column-addressed arrays. Custom front-end electronics were produced...... with the capability of transmitting and receiving on all elements, and the option of disabling the integrated apodization. The center frequency and -6-dB fractional bandwidth of the array elements were 2.77 ± 0.26 MHz and 102 ± 10%, respectively. The surface transmit pressure at 2.5 MHz was 590 ± 73 k...

  12. Optimization of the window function for digital hologram apodization in reconstructing the holographic image

    International Nuclear Information System (INIS)

    In this paper, an optimal window function used for digital hologram apodization in reconstructing the holographic image is presented, which is generated by a cosine window convolving with a rectangle window and has a flat top because of the rectangle shape of the hologram. The window’s parameters are optimized using a genetic algorithm to make sure that the sidelobes of the window are minimum. Numerical simulation results show that the new window has a sidelobe lower than that of the Tukey window, and experimental results show that apodization using this window can suppress the diffraction effectively in reconstructing the holographic image. (paper)

  13. Ultra-High-Efficiency Apodized Grating Coupler Using a Fully Etched Photonic Crystal

    DEFF Research Database (Denmark)

    Ding, Yunhong; Peucheret, Christophe; Ou, Haiyan

    2013-01-01

    We demonstrate an apodized fiber-to-chip grating coupler using fully etched photonic crystal holes on the silicon-on-insulator platform. An ultra-high coupling efficiency of 1.65 dB (68%) with 3 dB bandwidth of 60 nm is experimentally demonstrated.......We demonstrate an apodized fiber-to-chip grating coupler using fully etched photonic crystal holes on the silicon-on-insulator platform. An ultra-high coupling efficiency of 1.65 dB (68%) with 3 dB bandwidth of 60 nm is experimentally demonstrated....

  14. The Design of the Apodizing Functions for Guided-Wave EOTF

    Institute of Scientific and Technical Information of China (English)

    Jing Zhou(周静)

    2003-01-01

    A design method of the apodizing functions for guided-wave four-port electrooptic tunable filter (EOTF) is proposed. As an example, the specific form of Gaussian apodizing function is designed by analyzing the crosstalk performance of EOTF. Crosstalk is calculated based on the transient response of the filter to an input optical pulse. It is concluded that crosstalk level below -30 dB for 20 Gb/s data rates and 100 GHz channel spacing is achievable with presently available substrate dimensions.

  15. Rectangular spectral collocation

    KAUST Repository

    Driscoll, Tobin A.

    2015-02-06

    Boundary conditions in spectral collocation methods are typically imposed by removing some rows of the discretized differential operator and replacing them with others that enforce the required conditions at the boundary. A new approach based upon resampling differentiated polynomials into a lower-degree subspace makes differentiation matrices, and operators built from them, rectangular without any row deletions. Then, boundary and interface conditions can be adjoined to yield a square system. The resulting method is both flexible and robust, and avoids ambiguities that arise when applying the classical row deletion method outside of two-point scalar boundary-value problems. The new method is the basis for ordinary differential equation solutions in Chebfun software, and is demonstrated for a variety of boundary-value, eigenvalue and time-dependent problems.

  16. Detuning in apodized point-by-point fiber Bragg gratings: insights into the grating morphology.

    Science.gov (United States)

    Williams, Robert J; Krämer, Ria G; Nolte, Stefan; Withford, Michael J; Steel, M J

    2013-11-01

    Point-by-point (PbP) inscription of fiber Bragg gratings using femtosecond laser pulses is a versatile technique that is currently experiencing significant research interest for fiber laser and sensing applications. The recent demonstration of apodized gratings using this technique provides a new avenue of investigation into the nature of the refractive index perturbation induced by the PbP modifications, as apodized gratings are sensitive to variation in the average background index along the grating. In this work we compare experimental results for Gaussian- and sinc-apodized PbP gratings to a coupled-mode theory model, demonstrating that the refractive index perturbation induced by the PbP modifications has a negative contribution to the average background index which is small, despite the presence of strong reflective coupling. By employing Fourier analysis to a simplified model of an individual modification, we show that the presence of a densified shell around a central void can produce strong reflective coupling with near-zero change in the average background index. This result has important implications for the experimental implementation of apodized PbP gratings, which are of interest for a range of fiber laser and fiber sensing technologies. PMID:24216907

  17. Carbon/Carbon Pistons for Internal Combustion Engines

    Science.gov (United States)

    Taylor, A. H.

    1986-01-01

    Carbon/carbon piston performs same function as aluminum pistons in reciprocating internal combustion engines while reducing weight and increasing mechanical and thermal efficiencies of engine. Carbon/carbon piston concept features low piston-to-cylinder wall clearance - so low piston rings and skirts unnecessary. Advantages possible by negligible coefficient of thermal expansion of carbon/carbon.

  18. Piston rod assembly including an injection bonded piston head and fabrication method

    Energy Technology Data Exchange (ETDEWEB)

    Benton, T.L.; Dirkin, W.; Lund, C.E.

    1988-09-27

    This patent describes a piston rod assembly comprising a piston rod and a piston head. The rod extends coaxially beyond the piston head. The piston head has an internal annular groove defining with an external surface of the rod an annual space filled with adhesive to provide a bonded joint between the piston head and rod. The piston head engages the rod at the ends of the groove to seal off the ends of the groove. The piston head includes a radially enlarged center dam portion and a pair of reduced diameter end portions extending coaxially from opposite sides of the center dam portion. The center dam portion has an axial thickness, and the internal groove having an axial length greater than the axial thickness of the center dam portion. The annular groove extends axially beyond the opposite sides of the center dam portion for a substantial portion of the length of the reduced diameter end portions.

  19. Random rectangular Graphs

    CERN Document Server

    Estrada, Ernesto

    2015-01-01

    A generalization of the random geometric graph (RGG) model is proposed by considering a set of points uniformly and independently distributed on a rectangle of unit area instead of on a unit square \\left[0,1\\right]^{2}. The topological properties, such as connectivity, average degree, average path length and clustering, of the random rectangular graphs (RRGs) generated by this model are then studied as a function of the rectangle sides lengths a and b=1/a, and the radius r used to connect the nodes. When a=1 we recover the RGG, and when a\\rightarrow\\infty the very elongated rectangle generated resembles a one-dimensional RGG. We provided computational and analytical evidence that the topological properties of the RRG differ significantly from those of the RGG. The connectivity of the RRG depends not only on the number of nodes as in the case of the RGG, but also on the side length of the rectangle. As the rectangle is more elongated the critical radius for connectivity increases following first a power-law an...

  20. Effect of the friction produced by the piston and connecting rod on transverse piston movement

    Energy Technology Data Exchange (ETDEWEB)

    Essers, U.; Tschoeke, H.

    1983-03-01

    Practical investigation of the effect of friction on transverse piston movement is only possible through theoretical simulation. Such a simulation program has been developed and used by the Institute of Internal-Combustion Engines and Motor Vehicles of the University of Stuttgart. This analytical model covers all friction areas on the piston and connecting rod. As an example, the frictional forces and torques of a small diesel engine over one cycle are given. This analysis showed that the frictional forces between piston rings and their grooves and the frictional torque of the piston pin have the greatest effects on transverse piston movement near TDC.

  1. Imaging performance of annular apertures. IV - Apodization and point spread functions. V - Total and partial energy integral functions

    Science.gov (United States)

    Tschunko, H. F. A.

    1983-01-01

    Reference is made to a study by Tschunko (1979) in which it was discussed how apodization modifies the modulation transfer function for various central obstruction ratios. It is shown here how apodization, together with the central obstruction ratio, modifies the point spread function, which is the basic element for the comparison of imaging performance and for the derivation of energy integrals and other functions. At high apodization levels and lower central obstruction (less than 0.1), new extended radial zones are formed in the outer part of the central ring groups. These transmutation of the image functions are of more than theoretical interest, especially if the irradiance levels in the outer ring zones are to be compared to the background irradiance levels. Attention is then given to the energy distribution in point images generated by annular apertures apodized by various transmission functions. The total energy functions are derived; partial energy integrals are determined; and background irradiance functions are discussed.

  2. Casting of Motorcycle Piston from Aluminium Piston Scrap using Metallic Mould

    Directory of Open Access Journals (Sweden)

    Francis Uchenna OZIOKO

    2012-11-01

    Full Text Available The casting of motorcycle piston was carried out using metallic mould. The prepared piston sand core was positioned in the mould to provide casting with contours and cavities. The molten metal of required composition was poured into the metallic mould, allowed to solidify and take the desired shape of the cavity. Aluminium silicon piston scraps were used as the casting material. Melting of the aluminium piston scraps was achieved using local crucible furnace and finally pouring the molten metal into the metallic mould having the prepared piston sand core in place to obtain the piston. After fettling and cleaning, the casting was found to be good. The composition test revealed that the scrap piston was made from LM29 aluminium alloy. The cast piston was machined and subjected to performance rating test in a Jincheng AX100 motorcycle engine. The rating used was based on a scale from 1 to 10. The higher the rating, the better the evaluation of the piston in the specific area rated. Deposits are evaluated by appearance, ranging from 10 (clean - absence of deposits to 0.0 (maximum deposits. In spite of various production constraints the result of the performance test was good. The rating showed that the locally cast piston compared favourably with imported piston.

  3. Collapsible pistons for light-gas guns

    Science.gov (United States)

    Teng, R. N.

    1973-01-01

    Moving and expandable parts of gun consist of pump-tube diaphragm, piston, launch-tube diaphragm, and saboted projectile. As a result of improved piston design, pressure cycle has been significantly improved by smoother buildup, increasing muzzle velocities up to 50%.

  4. Fully etched apodized grating coupler on the SOI platform with −058 dB coupling efficiency

    DEFF Research Database (Denmark)

    Ding, Yunhong; Peucheret, Christophe; Ou, Haiyan;

    2014-01-01

    We design and fabricate an ultrahigh coupling efficiency (CE) fully etched apodized grating coupler on the silicon- on-insulator (SOI) platform using subwavelength photonic crystals and bonded aluminum mirror. Fabrication error sensitivity andcoupling angle dependence are experimentally investiga......We design and fabricate an ultrahigh coupling efficiency (CE) fully etched apodized grating coupler on the silicon- on-insulator (SOI) platform using subwavelength photonic crystals and bonded aluminum mirror. Fabrication error sensitivity andcoupling angle dependence are experimentally...

  5. A single-lithography SOI rib waveguide sensing circuit with apodized low back-reflection surface grating fiber coupling

    OpenAIRE

    Dubois, Valentin J.; Antelius, Mikael; Sohlström, Hans; Gylfason, Kristinn B.

    2012-01-01

    We present a single-lithography Mach-Zehnder interferometer sensor circuit, with integrated low back-reflection input and output grating couplers. The low back-reflection is accomplished by a duty cycle apodization optimized for coupling light between single-mode silica fibers and the nanometric silicon-on-insulator (SOI) rib-waveguides. We discuss the design, fabrication, and characterization of the circuit. The apodization profile of the gratings is algorithmically generated using eigenmode...

  6. Lipid-binding properties of human ApoD and Lazarillo-related lipocalins: functional implications for cell differentiation.

    Science.gov (United States)

    Ruiz, Mario; Sanchez, Diego; Correnti, Colin; Strong, Roland K; Ganfornina, Maria D

    2013-08-01

    Lipocalins are a family of proteins characterized by a conserved eight-stranded β-barrel structure with a ligand-binding pocket. They perform a wide range of biological functions and this functional multiplicity must relate to the lipid partner involved. Apolipoprotein D (ApoD) and its insect homologues, Lazarillo (Laz) and neural Lazarillo (NLaz), share common ancestral functions like longevity, stress resistance and lipid metabolism regulation, coexisting with very specialized functions, like courtship behavior. Using tryptophan fluorescence titration, we screened the binding of 15 potential lipid partners for NLaz, ApoD and Laz and uncovered several novel ligands with apparent dissociation constants in the low micromolar range. Retinoic acid (RA), retinol, fatty acids and sphingomyelin are shared ligands. Sterols, however, showed a species-specific binding pattern: cholesterol did not show strong binding to human ApoD, whereas NLaz and Laz did bind ergosterol. Among the lipocalin-specific ligands, we found that ApoD selectively binds the endocannabinoid anandamide but not 2-acylglycerol, and that NLaz binds the pheromone 7-tricosene, but not 7,11-heptacosadiene or 11-cis-vaccenyl acetate. To test the functional relevance of lipocalin ligand binding at the cellular level, we analyzed the effect of ApoD, Laz and NLaz preloaded with RA on neuronal differentiation. Our results show that ApoD is necessary and sufficient to allow for RA differentiating activity. Both human ApoD and Drosophila NLaz successfully deliver RA to immature neurons, driving neurite outgrowth. We conclude that ApoD, NLaz and Laz bind selectively to a different but overlapping set of lipid ligands. This multispecificity can explain their varied physiological functions.

  7. Binding and repressive activities of apolipoprotein E3 and E4 isoforms on the human ApoD promoter.

    Science.gov (United States)

    Levros, Louis-Charles; Labrie, Marilyne; Charfi, Cyndia; Rassart, Eric

    2013-12-01

    Apolipoprotein D (ApoD) gene expression is increased in several neurological disorders such as Alzheimer's disease (AD) and multiple sclerosis. We previously showed that transgenic mice that overexpress human ApoD show a better resistance against paraquat or OC43 coronavirus-induced neurodegeneration. Here, we identified several nuclear factors from the cortex of control and OC43-infected mice which bind a fragment of the proximal ApoD promoter in vitro. Of interest, we detected apolipoprotein E (ApoE). Human ApoE consists of three isoforms (E2, E3, and E4) with the E4 and E2 alleles representing a greater and a lower risk for developping AD, respectively. Our results show that ApoE is located in the nucleus and on the ApoD promoter in human hepatic and glioblastoma cells lines. Furthermore, overexpression of ApoE3 and ApoE4 isoforms but not ApoE2 significantly inhibited the ApoD promoter activity in U87 cells (E3/E3 genotype) cultured under normal or different stress conditions while ApoE knock-down by siRNA had a converse effect. Consistent with these results, we also demonstrated by ChIP assay that E3 and E4 isoforms, but not E2, bind the ApoD promoter. Moreover, using the Allen Brain Atlas in situ hybridization database, we observed an inverse correlation between ApoD and ApoE mRNA expression during development and in several regions of the mouse brain, notably in the cortex, hippocampus, plexus choroid, and cerebellum. This negative correlation was also observed for cortex layers IV-VI based on a new Transcriptomic Atlas of the Mouse Neocortical Layers. These findings reveal a new function for ApoE by regulating ApoD gene expression.

  8. Dynamics of crank-piston mechanisms

    CERN Document Server

    Davitashvili, Nodar

    2016-01-01

    This monograph focuses on the dynamical research work on crank-piston mechanisms considering basic and additional motions. In order to have full dynamical analyses of piston machines and their mechanisms, the book studies the crank-piston mechanisms with clearances in kinematic pairs. The tasks are carried out by focusing on friction, wear and impacts in mechanisms, as well as cracks formation in links and elasticity of details, with distributed and concentrated masses. Then, the reliability and durability of the mechanisms of piston machines is applied on oil and gas transportation. The monograph is meant for design specialists. It is also useful for specialists-manufacturers and designers of piston machines, scientists and lecturers, doctoral students.

  9. Analysing the effects of apodizing windows on local correlation tracking using Nirvana simulations of convection

    CERN Document Server

    Louis, Rohan E; Georgoulis, Manolis K; Küker, Manfred

    2015-01-01

    We employ different shapes of apodizing windows in the local correlation tracking (LCT) routine to retrieve horizontal velocities using numerical simulations of convection. LCT was applied on a time sequence of temperature maps generated by the Nirvana code with four different apodizing windows, namely--Gaussian, Lorentzian, trapezoidal and triangular, with varying widths. In terms of correlations (between the LCT-retrieved and simulated flow field), the triangular and the trapezoidal perform the best and worst, respectively. On segregating the intrinsic velocities in the simulations on the basis of their magnitudes, we find that for all windows, a significantly higher correlation is obtained for the intermediate and high-velocity bins and only modest or weak values in the low-velocity bins. The differences between the LCT-retrieved and simulated flow fields were determined spatially which show large residuals at or close to the boundary of granules. The extent to which the horizontal flow vectors retrieved b...

  10. Inverse-Gaussian-Apodized Fiber Bragg Grating for Dual Wavelength Lasing

    CERN Document Server

    Lin, Bo; Tjin, Swee Chuan; Tang, Dingyuan; Hao, Jianzhong; Tay, Chia Meng; Liang, Sheng

    2010-01-01

    A fiber Bragg grating (FBG) with an inverse-Gaussian apodization function is proposed and fabricated. It is shown that such a FBG possesses easily controllable dual-wavelength narrow transmission peaks. Incorporating such a FBG filter in a fiber laser with a linear cavity, stable dual-wavelength emission with 0.146 nm wavelength spacing is obtained. It provides a simple and low cost approach of achieving the dual-wavelength fiber laser operation.

  11. Uji Unjuk Kerja Pompa Pedal Multi Piston

    Directory of Open Access Journals (Sweden)

    Firman Yoko Sukwanputra

    2003-01-01

    Full Text Available Multi piston pedal pump is classified under reciprocating pump. This pump is generally designed for applications that require high capacity with low head. This pump is used for shallow well or to pump water in the system with low static and dynamic head. This experiment will examine the performance of multi piston pedal pump with capacity 3000 liter/hour. Two parameters, volumetric efficiency and overall efficiency will be examined during the experiment. The goal is to know the actual performance of this pump. Abstract in Bahasa Indonesia : Pompa pedal multi piston merupakan pompa bolak-balik (reciprocating pump yang umumnya dirancang untuk menghasilkan kapasitas yang cukup besar dengan head yang rendah. Pada umumnya digunakan pada sumur dangkal ataupun pemindahan air di mana perbedaan ketinggian antara suction dan discharge tidak terlalu besar. Pompa pedal multi piston yang akan diuji unjuk kerjanya merupakan pompa pedal multi piston dengan kapasitas rancangan 3000 liter/jam. Pengujian unjuk kerja dilakukan untuk mengukur efisiensi volumetris dan efisiensi overall. Dengan pengujian ini bisa diperoleh gambaran unjuk kerja pompa pedal multi piston yang dirancang tersebut. Kata kunci: pompa pedal multi piston, head, efisiensi volumetris, efisiensi overall.

  12. Opposed piston engine having fuel inlet through rod controlled piston port

    Energy Technology Data Exchange (ETDEWEB)

    Lively, E.P. Sr.

    1991-07-09

    This patent describes an internal combustion engine. It comprises at least one of each of an intake port, exhaust port and fuel inlet port; a pair of opposed pistons within a cylinder of the engine defining a combustion chamber; one of the pair of pistons opening and closing the at least one exhaust port, the one piston including the fuel inlet port therethrough; a connecting rod operatively connecting the one piston to a driven shaft, the connecting rod having an end portion which opens and closes the fuel inlet port.

  13. Spherical Joint Piston and Connecting Rod Developed

    Science.gov (United States)

    1996-01-01

    Under an interagency agreement with the Department of Energy, the NASA Lewis Research Center manages a Heavy-Duty Diesel Engine Technology (HDET) research program. The overall program objectives are to reduce fuel consumption through increased engine efficiency, reduce engine exhaust emissions, and provide options for the use of alternative fuels. The program is administered with a balance of research contracts, university research grants, and focused in-house research. The Cummins Engine Company participates in the HDET program under a cost-sharing research contract. Cummins is researching and developing in-cylinder component technologies for heavy-duty diesel engines. An objective of the Cummins research is to develop technologies for a low-emissions, 55-percent thermal efficiency (LE-55) engine. The best current-production engines in this class achieve about 46-percent thermal efficiency. Federal emissions regulations are driving this technology. Regulations for heavy duty diesel engines were tightened in 1994, more demanding emissions regulations are scheduled for 1998, and another step is planned for 2002. The LE-55 engine emissions goal is set at half of the 1998 regulation level and is consistent with plans for 2002 emissions regulations. LE-55 engine design requirements to meet the efficiency target dictate a need to operate at higher peak cylinder pressures. A key technology being developed and evaluated under the Cummins Engine Company LE-55 engine concept is the spherical joint piston and connecting rod. Unlike conventional piston and connecting rod arrangements which are joined by a pin forming a hinged joint, the spherical joint piston and connecting rod use a ball-and-socket joint. The ball-and-socket arrangement enables the piston to have an axisymmetric design allowing rotation within the cylinder. The potential benefits of piston symmetry and rotation are reduced scuffing, improved piston ring sealing, improved lubrication, mechanical and thermal

  14. Emergency braking for free piston energy converters

    OpenAIRE

    West, M.; Long, S.; Wang, J; Bingham, Chris; Howe, D.

    2005-01-01

    Free piston energy converters are a potential technology for future hybrid vehicles, as well as stationary power generation applications. A candidate 2-stroke system comprises of two opposing combustion chambers with a common piston rod, and integrated with a tubular permanent magnet electrical machine for the conversion of mechanical to electrical energy. A key issue for the ultimate adoption of such systems, however, is their robustness in the event of a fault to enable a safe shutdown, wit...

  15. Uji Unjuk Kerja Pompa Pedal Multi Piston

    OpenAIRE

    Firman Yoko Sukwanputra; Oegik Soegihardjo

    2003-01-01

    Multi piston pedal pump is classified under reciprocating pump. This pump is generally designed for applications that require high capacity with low head. This pump is used for shallow well or to pump water in the system with low static and dynamic head. This experiment will examine the performance of multi piston pedal pump with capacity 3000 liter/hour. Two parameters, volumetric efficiency and overall efficiency will be examined during the experiment. The goal is to know the actual perform...

  16. Fluid structure interaction in piston diaphragm pumps

    OpenAIRE

    Van Rijswick, R.; Van Rhee, C.

    2013-01-01

    Piston diaphragm pumps are used world-wide for the transport of aggressive and/or abrasive fluids in the chemical, mining and mineral processing industries. Figure 1 shows a cross section of a piston diaphragm pump as is used in the mining and mineral processing industries for the transport of mineral ores and tailings in the from of a solid water mixture, called a slurry.

  17. Systematic parametric design/calculation of the piston rod unit

    Science.gov (United States)

    Kacani, V.

    2015-08-01

    In this article a modern and economic method for the strength calculation of the piston rod unit and its components under different operating conditions will be presented. Herefore the commercial FEA - Software will be linked with the company-owned calculation tools. The parametric user input will be followed by an automatic Pre- and Postprocessing. Afterwards the strength calculation is processed on all critical points of the piston rod connection, assisted by an extra module, based on general standards and special codes for reciprocating compressors. In this process most arrangements of the piston rod unit as well as the special geometries of the single-components (piston, piston rod and piston nut) can be considered easily. In this article the modeling of the notches, especially on the piston rod, piston as well as the piston nut will be covered in detail.

  18. Drive piston assembly for a valve actuator assembly

    Science.gov (United States)

    Sun, Zongxuan

    2010-02-23

    A drive piston assembly is provided that is operable to selectively open a poppet valve. The drive piston assembly includes a cartridge defining a generally stepped bore. A drive piston is movable within the generally stepped bore and a boost sleeve is coaxially disposed with respect to the drive piston. A main fluid chamber is at least partially defined by the generally stepped bore, drive piston, and boost sleeve. First and second feedback chambers are at least partially defined by the drive piston and each are disposed at opposite ends of the drive piston. At least one of the drive piston and the boost sleeve is sufficiently configured to move within the generally stepped bore in response to fluid pressure within the main fluid chamber to selectively open the poppet valve. A valve actuator assembly and engine are also provided incorporating the disclosed drive piston assembly.

  19. Flows for rectangular matrix models

    OpenAIRE

    Lafrance, Rene; Myers, Robert C.

    1993-01-01

    Several new results on the multicritical behavior of rectangular matrix models are presented. We calculate the free energy in the saddle point approximation, and show that at the triple-scaling point, the result is the same as that derived from the recursion formulae. In the triple-scaling limit, we obtain the string equation and a flow equation for arbitrary multicritical points. Parametric solutions are also examined for the limit of almost-square matrix models. This limit is shown to provi...

  20. Stop-less Lyot coronagraph for exoplanet characterization: design, manufacturing, and tests of the apodizer

    Science.gov (United States)

    Vigan, A.; N'Diaye, M.; Dohlen, K.

    2014-07-01

    Upcoming high-contrast imagers will all provide spectroscopic capabilities for the characterization of directly detected giant planets in wide orbits. While integral field spectroscopy (IFS) can provide both spatial and spectral information, it is usually limited in terms of field of view and resolution. The alternative is to use long slit spectroscopy coupled with coronagraphy (LSC), which can easily provide higher resolution and larger field of view. The SPHERE instrument for the VLT provides a LSC mode in its near-infrared imager and spectrograph, IRDIS. However, the fact that the occulting coronagraphic mask is merged in the focal plane with the slit reduces significantly its capacity to attenuate the diffraction, limiting the high-contrast capabilities of the instrument at close angular separations (0.3"-0.4"). To improve the diffraction suppression of the LSC in IRDIS, we recently proposed to use the stop-less Lyot coronagraph (SLLC) to build an apodized long slit coronagraph (ALSC), and we demonstrated that it improves notably the performance at small angular separation, allowing the spectral analysis of colder planets. The design of the SLLC apodizer has been optimized for an implementation in SPHERE/IRDIS, and it has recently been manufactured before being inserted into the instrument during reintegration of SPHERE in Paranal. In the current work, we present the final design of the SLLC apodizer, its specifications for the manufacturing step, and the first results obtained on SPHERE. We compare the results between the simple LSC and the new ALSC, and we draw the conclusions on the advantages and drawbacks of our design.

  1. Lente intra-ocular multifocal difrativa apodizada: resultados Diffractive apodized multifocal intraocular lens: results

    Directory of Open Access Journals (Sweden)

    Virgilio Centurion

    2007-12-01

    Full Text Available OBJETIVO: Mostrar os resultados visuais e refracionais com lente intra-ocular multifocal difrativa apodizada. MÉTODOS: Estudo de 100 olhos de 50 pacientes com catarata, submetidos à facoemulsificação com implante bilateral de lente intra-ocular (LIO multifocal difrativa apodizada. Foi avaliada a acuidade visual binocular sem e com correção para longe e perto, a previsibilidade refracional e a freqüência de uso de óculos. RESULTADOS: A acuidade visual sem correção para longe foi de e " 20/30 em 97,56% dos olhos operados e e" J2 em 100%, sendo que 82% dos pacientes nunca usam óculos e 16% usam de forma esporádica. CONCLUSÃO: A LIO multifocal difrativa apodizada mostrou ser uma opção previsível, reproduzível e segura na correção dos vícios de refração para longe e perto durante a cirurgia da catarata, permitindo elevado índice de independência ao uso de óculos.OBJECTIVE: To show visual and refraction results using multifocal diffractive apodized intraocular lens. METHODS: The study of 100 eyes of 50 patients with cataract, submitted to phacoemulsification with bilateral implant of multifocal diffractive apodized intraocular lens (IOL. Binocular visual acuity was evaluated with and without correction for near and distance, and refraction previsibility and frequency of wearing glasses. RESULTS: Visual acuity without correction for distance was e" 20/30 in 97.56% of eyes operated on and e" J2 in 100%, of these 82% of patients never wear glasses and 16% wear glasses sporadically. CONCLUSION: Multifocal diffractive apodized IOL proved to be a foreseeable option, reproducible and safe in the correction of refraction errors for distance and near during cataract surgery, enabling a high rate of independence from the use of glasses.

  2. Apodization of Spurs in Radar Receivers Using Multi-Channel Processing

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). ISR Mission Engineering; Bickel, Douglas Lloyd [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). ISR Analysis and Applications

    2014-03-01

    Spurious energy in received radar data is a consequence of nonideal component and circuit behavior. This might be due to I/Q imbalance, nonlinear component behavior, additive interference (e.g. cross-talk, etc.), or other sources. The manifestation of the spurious energy in a range-Doppler map or image can be influenced by appropriate pulse-to-pulse phase modulation. Comparing multiple images having been processed with the same data but different signal paths and modulations allows identifying undesired spurs and then cropping or apodizing them.

  3. Analysis on characteristics of 1-D apodized and chirped photonic crystals containing negative refractive materials

    Institute of Scientific and Technical Information of China (English)

    TONG Kai; CUI Wei-wei; XU Xiao-hui; LI Zhi-quan

    2008-01-01

    Using transfer matrix method, the optical transmission properties of 1-D photonic crystals composed partially of negativerefraction media are analyzed. The transmission spectra of periodic photonic crystal, chirped photonic crystal and apodizedphotonic crystal are numerically simulated respectively. By contrast with optical transmission properties of ordinary photo-nic crystals made of positive refraction media, the transmission spectra of apodized photonic crystal become unregular, theBragg flat-headed area recurs but the peak of transmission does not change significantly. Futhermore, the band gap rangeof chirped photonic crystal diminishes gradually.

  4. Laboratory Demonstration of Phase Induced Amplitude Apodization (PIAA) Coronagraph with Better than 10(exp -9) Contrast

    Science.gov (United States)

    Kern, Brian; Guyon, Olivier; Kuhnert, Andreas; Niessner, Albert; Martinache, Frantz; Balasubramanian, Kunjithapatham

    2013-01-01

    We present coronagraphic images from the Phase Induced Amplitude Apodization (PIAA) coronagraph on NASA's High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Lab, showing contrasts of 5x10(exp -1) averaged from 2-4 lambda/D, in monochromatic light at 808 nm. In parallel with the coronagraph and its deformable mirror and coronagraphic wavefront control, we also demonstrate a low-order wavefront control system, giving 100 x rms suppression of introduced tip/tilt disturbances down to residual levels of 10(exp -3) lambda/D. Current limitations, as well as broadband (10% fractional bandpass) preliminary results are discussed.

  5. Sealing system for piston rod of hot gas engine

    Energy Technology Data Exchange (ETDEWEB)

    Lundholm, S.G.; Ringqvist, S.A.

    1980-11-25

    An improvement to a sealing system for restricting fluid flow around a piston rod between a piston cylinder and crankshaft space in a hot gas engine where a seal element is secured around the piston rod in an intermediate chamber, the improvement including a link in the crankshaft space connecting, and permitting relative radial motion between, the piston rod and the crosshead and an o-ring having a diameter substantially greater than that of the piston rod and being secured between a lower ring securing the seal element in place around the piston rod and a wall of the intermediate chamber for frictionally restricting radial movement of the lower ring.

  6. Experimental Investigation of Piston Rings for Internal Combustion Engines

    DEFF Research Database (Denmark)

    Christiansen, Jens; Klit, Peder; Vølund, Anders;

    2007-01-01

    load may be established by measuring the pressure distribution, i.e. the pressure drop in the piston ring package. Speed and temperature may also be established. The amount and distribution of oil present is, however, not easily determined. It is often assumed that it operates under fully flooded...... absorbed in the bearing. The following properties are measured: Oil film thickness - along liner (axial variation), oil film thickness - along piston ring (circumferential variation), piston tilt, temperature of piston rings and liner, pressure at piston lands and forces on piston rod. Since the frictional...

  7. Simultaneous high bit-rate format and mode conversion with a single tilted apodized few-mode fiber Bragg grating

    Science.gov (United States)

    Gao, Ya; Sun, Junqiang; Sima, Chaotan

    2016-10-01

    We propose an all-optical approach for simultaneous high bit-rate return-to-zero (RZ) to non-return-to-zero (NRZ) format and LP01 to LP11 mode conversion using a weakly tilted apodized few-mode fiber Bragg grating (TA-FM-FBG) with specific linear spectral response. The grating apodization profile is designed by utilizing an efficient inverse scattering algorithm and the maximum refractive index modulation is adjusted based on the grating tilt angle, according to Coupled-Mode Theory. The temporal performance and operation bandwidth of the converter are discussed. The approach provides potential favorable device for the connection of various communication systems.

  8. Insulated Piston Heads for Diesel Engines

    Science.gov (United States)

    Tricoire, A.; Kjellman, B.; Wigren, J.; Vanvolsem, M.; Aixala, L.

    2009-06-01

    Widely studied in the 1980s, the insulation of pistons in engines aimed at reducing the heat losses and thus increasing the indicated efficiency. However, those studies stopped in the beginning of the 1990s because of NO x emission legislation and also because of lower oil prices. Currently, with the improvement of exhaust after treatment systems (diesel particulate filter, selective catalytic reduction, and diesel oxidation catalyst) and engine technologies (exhaust gas recirculation), there are more trade-offs for NO x reduction. In addition, the fast rise of the oil prices tends to lead back to insulation technologies in order to save fuel. A 1 mm thick plasma sprayed thermal barrier coating with a graded transition between the topcoat and the bondcoat was deposited on top of a serial piston for heavy-duty truck engines. The effects of the insulated pistons on the engine performance are also discussed, and the coating microstructure is analyzed after engine test.

  9. NEW METHOD TO MEASURE PISTON SKIRT DIMENSIONS

    Institute of Scientific and Technical Information of China (English)

    Qin Yuexia; Hu Dejin

    2004-01-01

    The measurement of the middle-convex and varying ellipse profile of a piston skirt is a key technology because of its complex profile and high precision. Generally, a piston is measured on special device after it is machined. High accuracy can be achieved through this off-line measurement, but the result diverges from the actual dimension. Therefore, a no-contact in-site measurement system is proposed. A laser displacement meter is used to measure the profile of the piston skirt. A computer connected to the meter is used to process the measured data. A regression analysis method is used to process the ellipse section data. The method of moving average is used to process the middle-convex curve data. By using the given system, high measurement accuracy can be gained, and the production requirement is met.

  10. Numerical Simulation of Piston Ring Lubrication

    DEFF Research Database (Denmark)

    Felter, Christian Lotz

    2006-01-01

    This paper describes a numerical method that can be used to model the lubrication of piston rings. Classical lubrication theory is based on the Reynolds equation which is ap- plicable to confined geometries and open geometries where the flooding conditions are known. Lubrication of piston rings......, however, fall outside this category of problems since the piston rings might suffer from starved running conditions. This means that the com- putational domain where Reynold equation is applicable (including a cavitation criteria) is unknown. In order to overcome this problem the computational domain...... variables u, v, rho for the velocity components and density, respectively. Time integration is performed by a third order Runge-Kutta method. The set of equations is closed by the Dowson- Higginson equation for the relation between density and pressure. Boundary conditions are the non-slip condition...

  11. Apodized phase mask coronagraphs for arbitrary apertures. II. Comprehensive review of solutions for the vortex coronagraph

    CERN Document Server

    Carlotti, Alexis; Mawet, Dimitri

    2014-01-01

    With a clear circular aperture, the vortex coronagraph perfectly cancels an on-axis point source and offers a 0.9 or 1.75 lambda/D inner working angle for topological charge 2 or 4, respectively. Current and near-future large telescopes are on-axis, however, and the diffraction effects of the central obscuration, and the secondary supports are strong enough to prevent the detection of companions 1e-3 - 1e-5 as bright as, or fainter than, their host star. Recent advances show that a ring apodizer can restore the performance of this coronagraph by compensating for the diffraction effects of a circular central obscuration in a 1D modeling of the pupil. We extend this work and optimize apodizers for arbitrary apertures in 2D in order to tackle the diffraction effects of the spiders and other noncircular artefacts in the pupil. We use a numerical optimization scheme to compute hybrid coronagraph designs that combine the advantages of the vortex coronagraph (small in IWA) and of shaped pupils coronagraphs (robustne...

  12. Exoplanets imaging with a Phase-Induced Amplitude Apodization Coronagraph - I. Principle

    CERN Document Server

    Guyon, O; Galicher, R; Martinache, F; Ridgway, S T; Woodruff, R A; Guyon, Olivier; Pluzhnik, Eugene A.; Galicher, Raphael; Martinache, Frantz; Ridgway, Stephen T.; Woodruff, Robert A.

    2004-01-01

    Using 2 aspheric mirrors, it is possible to apodize a telescope beam without losing light or angular resolution: the output beam is produced by ``remapping'' the entrance beam to produce the desired light intensity distribution in a new pupil. We present the Phase-Induced Amplitude Apodization Coronagraph (PIAAC) concept, which uses this technique, and we show that it allows efficient direct imaging of extrasolar terrestrial planets with a small-size telescope in space. The suitability of the PIAAC for exoplanet imaging is due to a unique combination of achromaticity, small inner working angle (about 1.5 $\\lambda/d$), high throughput, high angular resolution and large field of view. 3D geometrical raytracing is used to investigate the off-axis aberrations of PIAAC configurations, and show that a field of view of more than 100 $\\lambda/d$ in radius is available thanks to the correcting optics of the PIAAC. Angular diameter of the star and tip-tilt errors can be compensated for by slightly increasing the size o...

  13. Piston-rotaxanes as molecular shock absorbers.

    Science.gov (United States)

    Sevick, E M; Williams, D R M

    2010-04-20

    We describe the thermomechanical response of a new molecular system that behaves as a shock absorber. The system consists of a rodlike rotaxane connected to a piston and tethered to a surface. The response of this system is dominated by the translational entropy of the rotaxane rings and can be calculated exactly. The force laws are contrasted with those for a rigid rod and a polymer. In some cases, the rotaxanes undergo a sudden transition to a tilted state when compressed. These piston-rotaxanes provide a potential motif for the design of a new class of materials with a novel thermomechanical response. PMID:20158174

  14. Development of deep drawn aluminum piston tanks

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J.C.; Bronder, R.L.; Kilgard, L.W.; Evans, M.C.; Ormsby, A.E.; Spears, H.R.; Wilson, J.D.

    1990-06-08

    An aluminum piston tank has been developed for applications requiring lightweight, low cost, low pressure, positive-expulsion liquid storage. The 3 liter (183 in{sup 3}) vessel is made primarily from aluminum sheet, using production forming and joining operations. The development process relied mainly on pressurizing prototype parts and assemblies to failure, as the primary source of decision making information for driving the tank design toward its optimum minimum-mass configuration. Critical issues addressed by development testing included piston operation, strength of thin-walled formed shells, alloy choice, and joining the end cap to the seamless deep drawn can. 9 refs., 8 figs.

  15. Engine piston having an insulating air gap

    Science.gov (United States)

    Jarrett, Mark Wayne; Hunold,Brent Michael

    2010-02-02

    A piston for an internal combustion engine has an upper crown with a top and a bottom surface, and a lower crown with a top and a bottom surface. The upper crown and the lower crown are fixedly attached to each other using welds, with the bottom surface of the upper crown and the top surface of the lower crown forming a mating surface. The piston also has at least one centrally located air gap formed on the mating surface. The air gap is sealed to prevent substantial airflow into or out of the air gap.

  16. Internal Cooling of the Piston Rod in Non-Lubricated Piston Compressors

    OpenAIRE

    Hammer, Christiane; Will, Gotthard; Hesse, Ullrich

    2012-01-01

    In non-lubricated piston compressors the wear of the piston rod packing rings is still a problem that needs to be considered. Due to the demands of high gas pressure and leak-tight sealing the frictional heat of the rings is causing high temperatures in the area of the piston rod packing. High temperatures are – among other factors – one reason for an increase of wear and thus for a lifetime reduction of the packing. To increase this lifetime – and so to increase the time between two technica...

  17. Staged combustion with piston engine and turbine engine supercharger

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Larry E. (Los Gatos, CA); Anderson, Brian L. (Lodi, CA); O' Brien, Kevin C. (San Ramon, CA)

    2011-11-01

    A combustion engine method and system provides increased fuel efficiency and reduces polluting exhaust emissions by burning fuel in a two-stage combustion system. Fuel is combusted in a piston engine in a first stage producing piston engine exhaust gases. Fuel contained in the piston engine exhaust gases is combusted in a second stage turbine engine. Turbine engine exhaust gases are used to supercharge the piston engine.

  18. Shield mining frame piston rod. Schildausbaugestell-Kolbenstange

    Energy Technology Data Exchange (ETDEWEB)

    Schuett, F.

    1981-05-02

    A piston rod for a shield mining frame for coal mining is described. This has radial outward connecting openings at the free end for hydraulic pipes. The plug-in connections are pushed in here and held with clamps. The piston rod part, in which these openings are situated, is made as a bar. The piston rod and bar form one part.

  19. THE ANALYSIS OF CAUSES OF LORRY PISTON COMBUSTION ENGINE DAMAGE

    Directory of Open Access Journals (Sweden)

    Mária Štefániková

    2012-02-01

    Full Text Available The article deals with analysis of causes of lorry piston combustion engine damage. For docummentation and analysis of causes was used macroscopical, microscopical and scanning electron microscopy. The analysis showed that the reason of fatal damage resides in production process of lorry combustion pistons which proved in implication of fatigue damage and subsequent burnout in two piston place.

  20. Correlation between off-axis illumination and apodized phase-contrast: two complementary microscopic phase-imaging modes.

    Science.gov (United States)

    Pelc, Radek; Hostounský, Zdenek; Otaki, Tatsuro

    2008-01-01

    Microscopic images of biological phase specimens of various optical thickness, acquired under off-axis illumination and apodized/conventional phase-contrast are compared. The luminance profiles in appropriately filtered apodized phase-contrast images compare well with those in the original off-axis illumination images. The two unfiltered image types also yield similar results in terms of quasi-three-dimensional surface (pseudo-relief) rendering, and thus are comparable in terms of the information contents (optical thickness map). However, the overall visual impression is very different as the visual cues to depth structure are present in the off-axis illumination images only. The comparison demonstrated in the present paper was made possible owing to apodization, which substantially reduces the "halo"/shade-off artifacts in the phase-contrast images. The results imply the possibility of combining the off-axis illumination and apodized phase-contrast imaging to examine specimens of medium optical thickness, in which the phase visualization capability of the two imaging modes substantially overlaps (e.g., larger cells or cell clusters). PMID:19021445

  1. Comparison of a new-generation sectorial addition multifocal intraocular lens and a diffractive apodized multifocal intraocular lens.

    NARCIS (Netherlands)

    Linden, J.W.M. van der; Velthoven, M. van; Meulen, I. van der; Nieuwendaal, C.; Mourits, M.; Lapid-Gortzak, R.

    2012-01-01

    PURPOSE: To compare visual, refractive, and satisfactory outcomes between a new-generation sectorial addition multifocal intraocular lens (IOL) (Lentis Mplus LS-312; study group) and a diffractive apodized multifocal IOL (Restor SN6AD1; control group). SETTING: Private practice, Driebergen, and Depa

  2. Symbolic Algorithmic Analysis of Rectangular Hybrid Systems

    Institute of Scientific and Technical Information of China (English)

    Hai-Bin Zhang; Zhen-Hua Duan

    2009-01-01

    This paper investigates symbolic algorithmic analysis of rectangular hybrid systems. To deal with the symbolic reachability problem, a restricted constraint system called hybrid zone is formalized for the representation and manipulation of rectangular automata state-spaces. Hybrid zones are proved to be closed over symbolic reachability operations of rectangular hybrid systems. They are also applied to model-checking procedures for verifying some important classes of timed computation tree logic formulas. To represent hybrid zones, a data structure called difference constraint matrix is defined.These enable us to deal with the symbolic algorithmic analysis of rectangular hybrid systems in an efficient way.

  3. Piston rod seal for a Stirling engine

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, W.

    1984-01-31

    In a piston rod seal for a Stirling engine, a hydrostatic bearing and differential pressure regulating valve are utilized to provide for a low pressure differential across a rubbing seal between the hydrogen and oil so as to reduce wear on the seal. 3 figs.

  4. Piston rod seal for a Stirling engine

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, Wilbur (Schenectady, NY)

    1984-01-01

    In a piston rod seal for a Stirling engine, a hydrostatic bearing and differential pressure regulating valve are utilized to provide for a low pressure differential across a rubbing seal between the hydrogen and oil so as to reduce wear on the seal.

  5. ISHTE hydrostatic piston corers. Final report

    International Nuclear Information System (INIS)

    This report describes piston corers employing high ambient pressure seawater for the energy source to drive the samplers into clay sediments of the deep ocean. The corers are a unique design using a self-contained hydraulic drive and control system developed especially for the requirements of the Subseabed Disposal Program's In-Situ Heat Transfer Experiment (ISHTE)

  6. Laser light stripe measurements assure correct piston assembly

    Science.gov (United States)

    Stein, Norbert; Frohn, Heiko

    1993-12-01

    Two VIKON-3D optical inspection systems assure the correct assembly of piston rings and guard rings in a new Volkswagen piston/rod assembly line. Both systems use laser light stripe measurements to locate and identify the relevant parts with high accuracy. The piston ring assembly is checked dynamically in video real time using laser light stripe and parallel projection techniques. In addition structured light is used to verify the correct piston/rod assembly. Both inspection systems are fully integrated into the manufacturing line. All types of pistons assembled can be checked without any mechanical changes to the measurement setup.

  7. Inherently flushing piston rod for a reciprocating pump

    Energy Technology Data Exchange (ETDEWEB)

    Besic, D.; Smith, W.C.

    1990-10-23

    This patent describes an inherently flushing piston rod for use in a reciprocating pump. It comprises: a piston portion having an axial bore formed therethrough, the axial bore having a first end and a second end, the first end of the axial bore lying in fluid contact with the external environment of the piston portion; a flexible diaphragm disposed within the axial bore through the piston portion whereby the flexible diaphragm and the piston portion define a reserve flushing zone; a pair of annular wiper elements extending radially from the piston portion, the annular wiper elements and the piston portion defining an annular flushing space therebetween; the piston portion having a radially-extending channel formed therethrough, the radially-extending channel fluidly connecting the axial bore through the piston portion and the annular flushing space; and a means for providing flushing fluid to the second end of the axial bore through the piston portion; a means for preventing flow from the axial bore through the piston portion to the means for supplying flushing fluid.

  8. Experimental Investigation of Piston Rings for Internal Combustion Engines

    DEFF Research Database (Denmark)

    Klit, Peder; Vølund, Anders

    2008-01-01

    conditions, but this is not the case in real life operation. These problems forms the basis for the experimental investigation. In large two-stroke engines the cylinder oil is supplied to the bearing at discrete locations on the cylinder liner at a specific rate at a certain time. The shifting in lubrication...... assembly. The aim of this paper is to investigate the tribological condition between a piston ring and cylinder. A test apparatus is used to study the interaction between a piston ring and a cylinder liner. In large two stroke engines with cross head bearings the piston height is small compared to smaller...... four stroke engines where the skirt transfers the guide forces to the cylinder liner. The power loss due to piston skirt friction is estimated by comparing two different piston designs. The piston ring experiences hydrodynamic, mixed and boundary lubrication and the squeeze effect of the piston ring...

  9. Numerical investigation of slow solitons in Bragg gratings with a hyperbolic tangent apodization

    International Nuclear Information System (INIS)

    This paper numerically and analytically investigates the formation and propagation motion of optical soliton in the Bragg grating. We choose the fibre Bragg grating with hyperbolic tangent apodization in the middle section in order to obtain slower solitons. Optical fibre soliton but not Bragg grating soliton is used as input pulse in the discussion, which is much more approximate to the light source for the practical purpose. We discuss in detail the effects of the soliton's velocity with some parameters in the process of transmission. The results show that by choosing special parameters, one can make the soliton slow-down with a little distortion and energy decay and obtain tunable time-delay on a small scale. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  10. SEARCHING FOR PLANETS IN HOLEY DEBRIS DISKS WITH THE APODIZING PHASE PLATE

    Energy Technology Data Exchange (ETDEWEB)

    Meshkat, Tiffany; Kenworthy, Matthew A. [Sterrewacht Leiden, P.O. Box 9513, Niels Bohrweg 2, 2300 RA Leiden (Netherlands); Bailey, Vanessa P.; Su, Kate Y. L.; Hinz, Philip M.; Smith, Paul S. [Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Mamajek, Eric E. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627-0171 (United States)

    2015-02-10

    We present our first results from a high-contrast imaging search for planetary mass companions around stars with gapped debris disks, as inferred from the stars' bright infrared excesses. For the six considered stars, we model the disks' unresolved infrared spectral energy distributions in order to derive the temperature and location of the disk components. With VLT/NaCo Apodizing Phase Plate coronagraphic L'-band imaging, we search for planetary mass companions that may be sculpting the disks. We detect neither disks nor companions in this sample, confirmed by comparing plausible point sources with archival data. In order to calculate our mass sensitivity limit, we revisit the stellar age estimates. One target, HD 17848, at 540 ± 100 Myr old is significantly older than previously estimated. We then discuss our high-contrast imaging results with respect to the disk properties.

  11. A SAR sidelobe suppression algorithm based on modified spatially variant apodization

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The existing spatially variant apodizations (SVAs) either cannot depress the sidelobes effectively or reduce the energy of the mainlobe.To improve this,a modified SVA (MSVA) is put forward in this paper,which expands the traditional filter from 3-taps to 5-taps and sets relevant parameters according to different sampling rates to get the excellent result that satisfies constrained optimization theory.A method for synthetic aperture radar (SAR) sidelobe control based on MSVA is presented,which applies MSVA to range compression and azimuth compression to control sidelobes.This method which is available for any Nyquist sampling rate can both depress the sidelobes effectively and keep the energy of the mainlobe and the resolution of the image.The method can reduce sidelobe levels more effectively than classical amplitude weighting while maintaining the image resolution,as demonstrated by the result of the experiment.

  12. Numerical investigation of slow solitons in Bragg gratings with a hyperbolic tangent apodization

    Institute of Scientific and Technical Information of China (English)

    Wang Kui-Ru; Cheng Jie-Lin; Sang Xin-Zhu; Chen Gong

    2011-01-01

    This paper numerically and analytically investigates the formation and propagation motion of optical soliton in the Bragg grating. We choose the fibre Bragg grating with hyperbolic tangent apodization in the middle section in order to obtain slower solitons. Optical fibre soliton but not Bragg grating soliton is used as input pulse in the discussion, which is much more approximate to the light source for the practical purpose. We discuss in detail the effects of the soliton's velocity with some parameters in the process of transmission. The results show that by choosing special parameters, one can make the soliton slow-down with a little distortion and energy decay and obtain tunable time-delay on a small scale.

  13. Nanostructure Secondary-Mirror Apodizing Mask for Transmitter Signal Suppression in a Duplex Telescope

    Science.gov (United States)

    Hagopian, John; Livas, Jeffrey; Shiri, Shahram; Getty, Stephanie; Tveekrem, June; Butler, James

    2012-01-01

    A document discusses a nanostructure apodizing mask, made of multi-walled carbon nanotubes, that is applied to the centers (or in and around the holes) of the secondary mirrors of telescopes that are used to interferometrically measure the strain of space-time in response to gravitational waves. The shape of this ultra-black mask can be adjusted to provide a smooth transition to the clear aperture of the secondary mirror to minimize diffracted light. Carbon nanotubes grown on silicon are a viable telescope mirror substrate, and can absorb significantly more light than other black treatments. The hemispherical reflectance of multi-walled carbon nanotubes grown at GSFC is approximately 3 to 10 times better than a standard aerospace paint used for stray light control. At the LISA (Laser Interferometer Space Antenna) wavelength of 1 micron, the advantage over paint is a factor of 10. Primarily, in the center of the secondary mirror (in the region of central obscuration, where no received light is lost) a black mask is applied to absorb transmitted light that could be reflected back into the receiver. In the LISA telescope, this is in the center couple of millimeters. The shape of this absorber is critical to suppress diffraction at the edge. By using the correct shape, the stray light can be reduced by approximately 10 to the 9 orders of magnitude versus no center mask. The effect of the nanotubes has been simulated in a stray-light model. The effect of the apodizing mask has been simulated in a near-field diffraction model. Specifications are geometry-dependent, but the baseline design for the LISA telescope has been modeled as well. The coatings are somewhat fragile, but work is continuing to enhance adhesion.

  14. Adiabatic Liquid Piston Compressed Air Energy Storage

    DEFF Research Database (Denmark)

    Petersen, Tage; Elmegaard, Brian; Pedersen, Allan Schrøder

    This project investigates the potential of a Compressed Air Energy Storage system (CAES system). CAES systems are used to store mechanical energy in the form of compressed air. The systems use electricity to drive the compressor at times of low electricity demand with the purpose of converting...... the mechanical energy into electricity at times of high electricity demand. Two such systems are currently in operation; one in Germany (Huntorf) and one in the USA (Macintosh, Alabama). In both cases, an underground cavern is used as a pressure vessel for the storage of the compressed air. Both systems...... a turbine when discharging. In this case, the liquid works effectively as a piston compressing the gas in the vessel, hence the name “Adiabatic Liquid Piston Compressed Air Energy Storage” (ALP-CAES). The compression ratio of the gas in the vessel (ratio between maximum and minimum pressure) is relatively...

  15. Quantum optomechanical piston engines powered by heat

    OpenAIRE

    Mari, Andrea; Farace, Alessandro; Giovannetti, Vittorio

    2014-01-01

    We study two different models of optomechanical systems where a temperature gradient between two radiation baths is exploited for inducing self-sustained coherent oscillations of a mechanical resonator. Viewed from a thermodynamic perspective, such systems represent quantum instances of self-contained thermal machines converting heat into a periodic mechanical motion and thus they can be interpreted as nano-scale analogues of macroscopic piston engines. Our models are potentially suitable for...

  16. ac electroosmosis in rectangular microchannels.

    Science.gov (United States)

    Campisi, Michele; Accoto, Dino; Dario, Paolo

    2005-11-22

    Motivated by the growing interest in ac electroosmosis as a reliable no moving parts strategy to control fluid motion in microfluidic devices for biomedical applications, such as lab-on-a-chip, we study transient and steady-state electrokinetic phenomena (electroosmosis and streaming currents) in infinitely extended rectangular charged microchannels. With the aid of Fourier series and Laplace transforms we provide a general formal solution of the problem, which is used to study the time-dependent response to sudden ac applied voltage differences in case of finite electric double layer. The Debye-Huckel approximation has been adopted to allow for an algebraic solution of the Poisson-Boltzmann problem in Fourier space. We obtain the expressions of flow velocity profiles, flow rates, streaming currents, as well as expressions of the complex hydraulic and electrokinetic conductances. We analyze in detail the dependence of the electrokinetic conductance on the extension of linear dimensions relative to the Debye length, with an eye on finite electric double layer effects. PMID:16351310

  17. Improving Free-Piston Stirling Engine Power Density

    Science.gov (United States)

    Briggs, Maxwell H.

    2016-01-01

    Analyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58% using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a maximum piston power increase of 14%. Analytical predictions are compared to experimental data showing close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.

  18. Numerical simulation of piston leakage over hermetic reciprocating compressors behavior.

    OpenAIRE

    Rigola Serrano, Joaquim; Pérez Segarra, Carlos David; Oliva Llena, Asensio

    2009-01-01

    Instantaneous flow leakage between piston and cylinder is numerically evaluated. Reynolds equation is solved to calculate the pressure leakage distribution through the piston in the compressor. Piston movement inside the cylinder is simulated from kinematic analysis of the connecting rod mechanical system and the respective force balances. An updated version of this model is here presented for different working range compressors and fluid refrigerants compressor chamber pressures distribution...

  19. A Dynamic Analysis of Free Piston Vuilleumier Cycle Heat Pumps

    OpenAIRE

    MATSUE, Junji; Nakazato, Takashi; Shirai, Hiroyuki

    2000-01-01

    A dynamic analysis of a free piston Vuilleumier cycle heat pump was performed by a time-stepping integration method. The nonlinear relationship between displacement and force for pistons was taken into account for the motion of reciprocating components, in addition to the pressure change of working gas, nonlinear viscous dissipative force due to an oscillating flow and discontinuous damping force caused by solid friction. The displacement of pistons and pressure changes in the Vuilleumier cyc...

  20. Improving Free-Piston Stirling Engine Specific Power

    Science.gov (United States)

    Briggs, Maxwell H.

    2015-01-01

    This work uses analytical methods to demonstrate the potential benefits of optimizing piston and/or displacer motion in a Stirling engine. Isothermal analysis was used to show the potential benefits of ideal motion in ideal Stirling engines. Nodal analysis is used to show that ideal piston and displacer waveforms are not optimal in real Stirling engines. Constrained optimization was used to identify piston and displacer waveforms that increase Stirling engine specific power.

  1. The effect of piston bowl temperature on diesel exhaust emissions

    OpenAIRE

    Ladommatos, N; Xiao, Z.; Zhao, H.

    2005-01-01

    In modern, high-speed, direct injection diesel engines for passenger vehicles, there is extensive impingement of the fuel sprays on to the piston bowl walls. Recent trends towards smaller engine sizes, equipped with high-pressure common-rail fuel injection systems, have tended to increase the spray/piston wall interaction. This paper describes tests carried out in a high-speed direct injection automotive diesel engine, during which the temperature of the piston was increased in a controlled m...

  2. Human ApoD, an apolipoprotein up-regulated in neurodegenerative diseases, extends lifespan and increases stress resistance in Drosophila.

    Science.gov (United States)

    Muffat, Julien; Walker, David W; Benzer, Seymour

    2008-05-13

    Apolipoprotein D (ApoD) expression increases in several neurological disorders and in spinal cord injury. We provide a report of a physiological role for human ApoD (hApoD): Flies overexpressing hApoD are long-lived and protected against stress conditions associated with aging and neurodegeneration, including hyperoxia, dietary paraquat, and heat stress. We show that the fly ortholog, Glial Lazarillo, is strongly up-regulated in response to these extrinsic stresses and also can protect in vitro-cultured cells in situations modeling Alzheimer's disease (AD) and Parkinson's disease (PD). In adult flies, hApoD overexpression reduces age-associated lipid peroxide accumulation, suggesting a proximal mechanism of action. Similar data obtained in the mouse [Ganfornina, M.D., et al., (2008) Apolipoprotein D is involved in the mechanisms regulating protection from oxidative stress. Aging Cell 10.1111/j.1474-9726.2008.00395.] as well as in plants (Charron et al., personal communication) suggest that ApoD and its orthologs play an evolutionarily conserved role in response to stress, possibly managing or preventing lipid peroxidation.

  3. Stress Analysis of Rectangular Boxes Using Fem

    Directory of Open Access Journals (Sweden)

    D.G. Lokhande

    2014-04-01

    Full Text Available Extensive experimental & theoretical contributions have been made to the study of open box structures, but few references dealing with closed boxes have been found. When a rectangular box structure is subjected to certain pressure, stress analysis of rectangular box is necessary to avoid the failure during working condition. In this work, it is proposed to evaluate the stresses in rectangular box by changing L/B ratios 1, 1.5, 2 for different thicknes of 2.5, 5, 7.5 mm & varying fillet radius, using finite element method.To validate finite element stresses, it is necessary to compare these stresses with analytical approach. From the FE analysis of rectangular box, it is seen that cubical box having the lesser stresses & better for stress distribution due to symmetry.The stiffners further reduces the stresses in boxes

  4. Thermal Impedance of Rectangular Microwave Oven Linings

    Institute of Scientific and Technical Information of China (English)

    SHIShang-zhao; XUFu-qiu; 等

    1996-01-01

    Amodel was preseted for calcultaing the thermal impedance of the insulation and refractory linings of rectangular microwave ovens,of which the oven cavity's dimensions are relatively small,while the linings re relatively thick.

  5. Internal position and limit sensor for free piston machines

    Science.gov (United States)

    Holliday, Ezekiel S. (Inventor); Wood, James Gary (Inventor)

    2012-01-01

    A sensor for sensing the position of a reciprocating free piston in a free piston Stirling machine. The sensor has a disk mounted to an end face of the power piston coaxially with its cylinder and reciprocating with the piston The disk includes a rim around its outer perimeter formed of an electrically conductive material A coil is wound coaxially with the cylinder, spaced outwardly from the outer perimeter of the disk and mounted in fixed position relative to the pressure vessel, preferably on the exterior of the pressure vessel wall.

  6. producción de ApoD en un sistema de expresión eucariota y estudio de su localización intracelular tras la endocitosis

    OpenAIRE

    Pascua Maestro, Raquel

    2013-01-01

    la apolipoproteina ApoD se expresa en el sistema nervioso durante su desarrollo y aumenta con el envejecimiento y la neurodegeneración. Estudios previos han demostrado que ApoD se sobrexpresa en respuesta a estrés como el tratamiento con agentes pro-oxidantes. Nuestros datos sugieren que cuando una célula sufre estrés oxidativo, ApoD es endocitada y podría llegar hasta compartimentos subcelulares como los lisosomas. Proteger la membrana lisosomal sería suficiente para explicar que ApoD puede ...

  7. Evaluation of TEP Deaeration Tower Rectangular Flange

    Institute of Scientific and Technical Information of China (English)

    WANG; Zhi-hao

    2013-01-01

    The rectangular flange is adapted in the heater of TEP deaeration tower(Fig.1).The rectangular flange is no-round type flange,the evaluation of which is worked on equivalent round flange method.Thecalculation is based on no-round type flange evaluation chapter in HGT 20582—2011 Steel chemical vessel strength calculation code.The loads on the flange are inner pressure,nozzle loads and seismic loads.The nozzle loads is

  8. Analysis of reciprocating compressor piston rod failures

    Energy Technology Data Exchange (ETDEWEB)

    Tripp, H.A.; Drosjack, M.J.

    1984-02-01

    This report presents the analysis of five piston rod failures which occurred on reciprocating compressors. Calculations are shown for rod stress which includes nominal rod loading sources as well as additional loads due to unusual pressure losses in the compressor valves, flexure of the rods due to misalignment, and manufacturing errors. The additional loads were incorporated on the basis of field measurements. The stress values are used with Baquin's equation to produce fatigue life curves for the rods. Based on the calculations, recommendations for modified rods were made. The calculation procedures are described in a manner which will permit their application to other reciprocating compressors.

  9. Stability analysis of free piston Stirling engines

    Science.gov (United States)

    Bégot, Sylvie; Layes, Guillaume; Lanzetta, François; Nika, Philippe

    2013-03-01

    This paper presents a stability analysis of a free piston Stirling engine. The model and the detailed calculation of pressures losses are exposed. Stability of the machine is studied by the observation of the eigenvalues of the model matrix. Model validation based on the comparison with NASA experimental results is described. The influence of operational and construction parameters on performance and stability issues is exposed. The results show that most parameters that are beneficial for machine power seem to induce irregular mechanical characteristics with load, suggesting that self-sustained oscillations could be difficult to maintain and control.

  10. Quantum optomechanical piston engines powered by heat

    Science.gov (United States)

    Mari, A.; Farace, A.; Giovannetti, V.

    2015-09-01

    We study two different models of optomechanical systems where a temperature gradient between two radiation baths is exploited for inducing self-sustained coherent oscillations of a mechanical resonator. From a thermodynamic perspective, such systems represent quantum instances of self-contained thermal machines converting heat into a periodic mechanical motion and thus they can be interpreted as nano-scale analogues of macroscopic piston engines. Our models are potentially suitable for testing fundamental aspects of quantum thermodynamics in the laboratory and for applications in energy efficient nanotechnology.

  11. Fluid powered linear piston motor with harmonic coupling

    Energy Technology Data Exchange (ETDEWEB)

    Raymond, David W.

    2016-09-20

    A motor is disclosed that includes a module assembly including a piston that is axially cycled. The piston axial motion is coupled to torque couplers that convert the axial motion into rotary motion. The torque couplers are coupled to a rotor to rotate the rotor.

  12. Experimental Piston Ring Tribology for Marine Diesel Engines

    DEFF Research Database (Denmark)

    Klit, Peder; Vølund, Anders

    2008-01-01

    A very important condition for describing the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. It is often assumed that piston rings operate under fully flooded conditions, but this is not the case in real life operation. In large two-stroke engines...

  13. TRIBOLOGICAL PERFORMANCE OF PISTON RING IN MARINE DIESEL ENGINE

    DEFF Research Database (Denmark)

    Imran, Tajammal; Klit, Peder; Felter, Christian;

    From a tribology point of view, it is the two dead centers that are the main area of interest for experimental study of piston rings in large marine diesel engines. Therefore, in this work the performance of piston rings is studied to mark the importance of the two dead centers. A test rig based...

  14. Reduction of HCCI combustion noise through piston crown design

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr; Schramm, Jesper

    2010-01-01

    Seven shapes of piston crowns have been evaluated for their ability to reduce HCCI knock and transmission of combustion noise to the engine. The performance of each piston crown was evaluated with measurements of cylinder pressure, engine vibration and acoustic sound pressure measured one meter a...

  15. Experimental Thermal Analysis of Diesel Engine Piston and Cylinder Wall

    Directory of Open Access Journals (Sweden)

    Subodh Kumar Sharma

    2015-01-01

    Full Text Available Knowledge of piston and cylinder wall temperature is necessary to estimate the thermal stresses at different points; this gives an idea to the designer to take care of weaker cross section area. Along with that, this temperature also allows the calculation of heat losses through piston and cylinder wall. The proposed methodology has been successfully applied to a water-cooled four-stroke direct-injection diesel engine and it allows the estimation of the piston and cylinder wall temperature. The methodology described here combines numerical simulations based on FEM models and experimental procedures based on the use of thermocouples. Purposes of this investigation are to measure the distortion in the piston, temperature, and radial thermal stresses after thermal loading. To check the validity of the heat transfer model, measure the temperature through direct measurement using thermocouple wire at several points on the piston and cylinder wall. In order to prevent thermocouple wire entanglement, a suitable pathway was designed. Appropriate averaged thermal boundary conditions such as heat transfer coefficients were set on different surfaces for FE model. The study includes the effects of the thermal conductivity of the material of piston, piston rings, and combustion chamber wall. Results show variation of temperature, stresses, and deformation at various points on the piston.

  16. Computational Modelling of Piston Ring Dynamics in 3D

    Directory of Open Access Journals (Sweden)

    Dlugoš Jozef

    2014-12-01

    Full Text Available Advanced computational models of a piston assembly based on the level of virtual prototypes require a detailed description of piston ring behaviour. Considering these requirements, the piston rings operate in regimes that cannot, in general, be simplified into an axisymmetric model. The piston and the cylinder liner do not have a perfect round shape, mainly due to machining tolerances and external thermo-mechanical loads. If the ring cannot follow the liner deformations, a local loss of contact occurs resulting in blow-by and increased consumption of lubricant oil in the engine. Current computational models are unable to implement such effects. The paper focuses on the development of a flexible 3D piston ring model based on the Timoshenko beam theory using the multibody system (MBS. The MBS model is compared to the finite element method (FEM solution.

  17. Piston motion in the perfect-conductive magnetizable uncompressible fluid

    Energy Technology Data Exchange (ETDEWEB)

    Naletova, V.A.

    1977-01-01

    A solution is given for the movement of a perfect conductive solid horizontal piston at a constant velocity u, parallel to the plane of the piston, in a perfect conductive magnetizable uncompressible fluid in an applied magnetic field H/sub 0/. Either a shock wave, a centered wave, or a alvenian fracture, or a combination of an alvenian fracture and waves can be propagated in front of the piston under these conditions. In this case either the shock or centered wave is propagated at first, followed by the movement of the alvenian fracture. Either case is manifested at such velocities. When the piston moves along the boundary, the piston-medium can flow as a surface current which can be found from the solution to the problem. 3 references, 3 figures.

  18. Piston ring microwelding: Field/lab correlation and prevention

    Energy Technology Data Exchange (ETDEWEB)

    Shuster, M.; Mahler, F.; Deis, M. [Dana Corp., Ottawa Lake, MI (United States). Advanced Technology Resource Group; Macy, D.; Frame, R. [Dana Corp., Richmond, IN (United States). Perfect Circle Products Div.

    1996-12-31

    This paper will discuss the microwelding phenomenon between aluminum pistons and iron piston rings in internal combustion engines. The mechanism of microwelding as observed on field run engine hardware has been correlated with the microwelding mechanism generated in an accelerated laboratory bench test. Hardness distribution measurements, metallography, scanning electron microscopy, and EDS spectrometer have been used in the analysis of this surface damage mechanism. In this work, the metallurgical parameters were formulated which describe the microwelding phenomenon after field usage and after accelerated testing. It was demonstrated that the high output water-cooled two-stroke engine accelerated bench test reproduces the field run engine microwelding phenomenon in 30 minutes. It was shown that the best prevention of the microwelding phenomenon was provided when the piston and piston ring surfaces were separated by a soft, wear and heat resistant coating, integrally bonded to the piston ring.

  19. Neutron collimator with rectangular beam profile

    Energy Technology Data Exchange (ETDEWEB)

    Cussen, L.D. E-mail: leo.cussen@vu.edu.au; Hoeghoj, P.; Anderson, I.S

    2001-03-21

    Several Soller slit-type neutron collimators which give rectangular profiles of transmission as a function of angular divergence have been constructed. The collimators accept a beam of realistic dimensions - greater than 12x22 mm{sup 2} in all cases. The blades of the collimators are 280 {mu}m thick wafers of single-crystal silicon each coated with a Ni-Gd-Ni multilayer on one side. Tests at a neutron wavelength of 7.5 A confirm that the transmission profiles are rectangular. Tests at a wavelength of 4.2 A show that two such collimators rocked against each other give dramatically enhanced transmission and resolution by comparison with conventional collimators. This is the first such demonstration of increased counting rates in a scan on an instrument from rectangular profile collimators, an effect expected but not produced for over 40 years.

  20. Neutron collimator with rectangular beam profile

    CERN Document Server

    Cussen, L D; Anderson, I S

    2001-01-01

    Several Soller slit-type neutron collimators which give rectangular profiles of transmission as a function of angular divergence have been constructed. The collimators accept a beam of realistic dimensions - greater than 12x22 mm sup 2 in all cases. The blades of the collimators are 280 mu m thick wafers of single-crystal silicon each coated with a Ni-Gd-Ni multilayer on one side. Tests at a neutron wavelength of 7.5 A confirm that the transmission profiles are rectangular. Tests at a wavelength of 4.2 A show that two such collimators rocked against each other give dramatically enhanced transmission and resolution by comparison with conventional collimators. This is the first such demonstration of increased counting rates in a scan on an instrument from rectangular profile collimators, an effect expected but not produced for over 40 years.

  1. Neutron collimator with rectangular beam profile

    International Nuclear Information System (INIS)

    Several Soller slit-type neutron collimators which give rectangular profiles of transmission as a function of angular divergence have been constructed. The collimators accept a beam of realistic dimensions - greater than 12x22 mm2 in all cases. The blades of the collimators are 280 μm thick wafers of single-crystal silicon each coated with a Ni-Gd-Ni multilayer on one side. Tests at a neutron wavelength of 7.5 A confirm that the transmission profiles are rectangular. Tests at a wavelength of 4.2 A show that two such collimators rocked against each other give dramatically enhanced transmission and resolution by comparison with conventional collimators. This is the first such demonstration of increased counting rates in a scan on an instrument from rectangular profile collimators, an effect expected but not produced for over 40 years

  2. Rectangular-to-circular groove waveguide junction

    Institute of Scientific and Technical Information of China (English)

    CUI; Licheng; (崔立成); YANG; Hongsheng; (杨鸿生)

    2003-01-01

    Mode matching method is used to analyze the scattering characteristics of the rectangular-to-circular groove waveguide junction. Firstly, the scattering matrix equation is obtained by matching the electromagnetic fields at the boundary of the junction. The scattering coefficients can be obtained from the equation. Secondly the scattering characteristics of the iris with rectangular window positioned in circular groove waveguide are briefly analyzed. Thirdly, the convergent problem is discussed and the numerical results are given. At last experiment is made and good agreement is found between the calculated results and the measured results.

  3. Electrochemical apparatus comprising modified disposable rectangular cuvette

    Science.gov (United States)

    Dattelbaum, Andrew M; Gupta, Gautam; Morris, David E

    2013-09-10

    Electrochemical apparatus includes a disposable rectangular cuvette modified with at least one hole through a side and/or the bottom. Apparatus may include more than one cuvette, which in practice is a disposable rectangular glass or plastic cuvette modified by drilling the hole(s) through. The apparatus include two plates and some means of fastening one plate to the other. The apparatus may be interfaced with a fiber optic or microscope objective, and a spectrometer for spectroscopic studies. The apparatus are suitable for a variety of electrochemical experiments, including surface electrochemistry, bulk electrolysis, and flow cell experiments.

  4. APODIZED PUPIL LYOT CORONAGRAPHS FOR ARBITRARY APERTURES. IV. REDUCED INNER WORKING ANGLE AND INCREASED ROBUSTNESS TO LOW-ORDER ABERRATIONS

    Energy Technology Data Exchange (ETDEWEB)

    N' Diaye, Mamadou; Pueyo, Laurent; Soummer, Rémi, E-mail: mamadou@stsci.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2015-02-01

    The Apodized Pupil Lyot Coronagraph (APLC) is a diffraction suppression system installed in the recently deployed instruments Palomar/P1640, Gemini/GPI, and VLT/SPHERE to allow direct imaging and spectroscopy of circumstellar environments. Using a prolate apodization, the current implementations offer raw contrasts down to 10{sup –7} at 0.2 arcsec from a star over a wide bandpass (20%), in the presence of central obstruction and struts, enabling the study of young or massive gaseous planets. Observations of older or lighter companions at smaller separations would require improvements in terms of the inner working angle (IWA) and contrast, but the methods originally used for these designs were not able to fully explore the parameter space. We propose a novel approach to improve the APLC performance. Our method relies on the linear properties of the coronagraphic electric field with the apodization at any wavelength to develop numerical solutions producing coronagraphic star images with high-contrast region in broadband light. We explore the parameter space by considering different aperture geometries, contrast levels, dark-zone sizes, bandpasses, and focal plane mask sizes. We present an application of these solutions to the case of Gemini/GPI with a design delivering a 10{sup –8} raw contrast at 0.19 arcsec and offering a significantly reduced sensitivity to low-order aberrations compared to the current implementation. Optimal solutions have also been found to reach 10{sup –10} contrast in broadband light regardless of the aperture shape, with effective IWA in the 2-3.5 λ/D range, therefore making the APLC a suitable option for the future exoplanet direct imagers on the ground or in space.

  5. CFD Analysis of an Axial Piston Pump

    OpenAIRE

    Kumar, Sushil

    2010-01-01

    En el ámbito de la Oleohidráulica, las bombas de pistón poseen los diseños más sofisticados, de hecho, las bombas de pistones son las únicos capaces de trabajar a altas presiones, además de poseer el mejor rendimiento de todo el grupo de bombas existentes. Sin embargo, cabe señalar que todos los diseños de las bombas de pistón, se basan principalmente en la experiencia de los diseñadores, por lo tanto no existen herramientas matemáticas para optimizar el diseño de las diferentes partes de las...

  6. Transient Characteristics of Free Piston Vuilleurnier Cycle Heat Pumps

    Science.gov (United States)

    Matsue, Junji; Fujimoto, Norioki; Shirai, Hiroyuki

    A dynamic analysis of a free piston Vuilleumier cycle heat pump was performed using a time-stepping integration method to investigate transient characteristics under power controlling. The nonlinear relationship between displacement and force for pistons was taken into account for the motion of reciprocating components. The force for pistons is mainly caused by the pressure change of working gas varying with piston displacements; moreover nonlinear viscous dissipative force due to the oscillating flow of working gas in heat exchangers and discontinuous damping force caused by solid friction at piston seals and rod seals are included. The displacements of pistons and pressure changes in the Vuilleumier cycle heat pump were integrated by an ideal isothermal thermodynamic relationship. It was assumed that the flow friction was proportional to the kinematic pressure of working gas, and that the solid friction at the seals was due to the functions of the working gas pressure and the tension of seal springs. In order to investigate the transient characteristics of a proposed free piston Vuilleumier cycle heat pump machine when hot-side working gas temperatures and alternate force were changed, some calculations were performed and discussed. These calculation results make clear transient characteristics at starting and power controlling. It was further found that only a small amount of starter power is required in particular conditions. During controlling, the machine becomes unstable when there is ar elatively large reduction in cooling or heating power. Therefore, an auxiliary device is additionally needed to obtain stable operation, such as al inear motor.

  7. Piston ring lubrication and hydrocarbon emissions from internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Froelund, K.

    1997-11-01

    Is it the intention with this project to improve the existing hydrocarbon emission model at the Institute by combining it with a model for predicting the piston ring lubrication. The piston ring lubrication model should be experimentally verified to ensure the validity of the model. The following items were the objectives of the current study: Develop a piston ring lubrication model. This implies the development of a ring-pack gas flow model; Examine the response of the piston ring lubrication model to changing engineer conditions. Especially, it would be interesting to look at the engine warm-up phase since this is the phase where the engine-out emissions are highest and where the commonly used three way catalyst is not capable of converting the engine-out emissions, thereby leading the engine-out emissions directly out in to the environment with the exhaust gases; In order to verify the piston ring lubrication model the lubricant distribution on the cylinder liner should be investigated experimentally. Here again it would be of great interesting to look at the engine warm-up phase; The piston ring lubrication model should be adjusted for application together with the new hydrocarbon emission model for SI-engines at the Institute in order to increase the accuracy of the latter; The piston ring lubrication model could be used for describing the transport of PAH`s in diesel engines. (EG)

  8. Piston diameter in stapes surgery. Does it have a bearing?

    Directory of Open Access Journals (Sweden)

    Neha Gupta

    2014-01-01

    Full Text Available Aims and Objectives: This prospective randomized controlled trial was done to study the effect of piston diameter on hearing outcomes after stapedotomy. Materials and Methods: All the patients diagnosed to have otosclerosis were included in the study. A total of 52 patients were studied ranging in age from 18 to 50 years. The subjects were randomized into two groups, that is, 0.4 mm piston (group A and 0.6 mm piston (group B. The subjects were taken up for small fenestra stapedotomy using either a 0.4 or 0.6 mm piston. The main outcome measures were hearing improvement, air-bone gap closure, and overclosure of air-bone gap. Results: There was no statistical difference in hearing improvement in two different piston diameters, 0.4 and 0.6 mm at speech frequencies. In group A, the air-bone gap improvement in the third follow-up was not significant (P > 0.05, whereas group B showed a statistically significant improvement (P = 0.003. The mean overclosure of air-bone gap was better in patients with 0.4 mm piston at speech frequencies and also at 250 Hz. Significantly, overclosure of air-bone gap at higher frequencies (4 and 8 KHz was seen only with a smaller sized piston. (0.4 mm. Discussion: We analyzed the effect of piston diameter on the hearing results after small fenestra stapedotomy by using similar surgical procedure and similar prosthesis in all patients. Conclusion: There is evidence to suggest that 0.4 mm piston may be better suited for providing optimum hearing results.

  9. Role Of Computational Simulations In The Design Of Piston Rings

    Directory of Open Access Journals (Sweden)

    Novotný Pavel

    2015-06-01

    Full Text Available The paper presents computational approaches using modern strategies for a dynamic piston ring solution as a fluid structural problem. Computational model outputs can be used to understand design parameter influences on defined results of a primarily integral character. Piston ring dynamics incorporates mixed lubrication conditions, the influence of surface roughness on oil film lubrication, the influence of ring movement on gas dynamics, oil film formulation on a cylinder liner and other significant influences. The solution results are presented for several parameters of SI engine piston rings.

  10. Lubricantless piston rod seals for pressures up to 18 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Zakharenko, V.P.; Novikov, I.I.

    1984-03-01

    This article describes how seals for piston rods with flat packings are used in compressors for compressing gases without contaminating liquid lubricants. The use of nonmetallic self-lubricating materials and special seal designs of piston rods and plungers allow the dry running of compressors. Compositions based on fluorinol-4 greatly enlarge the range of operational parameters of lubricantless seals. Polyamide ATM-2 is highly efficient as lubricant seals of low-pressure compressor piston rods. Technological and operating advantages of lubricantless seals with flat rings include the design simplicity, the high gas tightness throughout the run between the repairs, reliability, and prolonged efficiency.

  11. Comparing the Volumes of Rectangular Prisms

    Science.gov (United States)

    Assuah, Charles K.; Wiest, Lynda R.

    2010-01-01

    Can middle-grades students determine which of two rectangular prisms has a larger volume? Can they do so without using a formula? Geometry, and particularly the concept of volume, is important in many subjects, such as physics and chemistry. Students greatly enhance their mathematics knowledge when they make generalizations and construct arguments…

  12. Demagnetizing effects in stacked rectangular prisms

    International Nuclear Information System (INIS)

    A numerical, magnetostatic model of the internal magnetic field of a rectangular prism is extended to the case of a stack of rectangular prisms. The model enables the calculation of the spatially resolved, three-dimensional internal field in such a stack given any magnetic state function, stack configuration, temperature distribution and applied magnetic field. In this paper the model is applied to the case of a stack of parallel, ferromagnetic rectangular prisms and the resulting internal field is found as a function of the orientation of the applied field, the number of prisms in the stack, the spacing between the prisms and the packing density of the stack. The results show that the resulting internal field is far from being equal to the applied field and that the various stack configurations investigated affect the resulting internal field significantly and non-linearly. The results have a direct impact on the design of, e.g., active magnetic regenerators made of stacked rectangular prisms in terms of optimizing the internal field.

  13. BIVARIATE FRACTAL INTERPOLATION FUNCTIONS ON RECTANGULAR DOMAINS

    Institute of Scientific and Technical Information of China (English)

    Xiao-yuan Qian

    2002-01-01

    Non-tensor product bivariate fractal interpolation functions defined on gridded rectangular domains are constructed. Linear spaces consisting of these functions are introduced.The relevant Lagrange interpolation problem is discussed. A negative result about the existence of affine fractal interpolation functions defined on such domains is obtained.

  14. Tribological Performance of Different Geometries of Piston Rings in Marine Diesel Engines

    DEFF Research Database (Denmark)

    Imran, Tajammal; Klit, Peder; Felter, Christian;

    Friction in the piston ring package (piston, piston rings and liner) is a major source of power consumption in two stroke marine diesel engines. It is well-known that a typical piston ring operates under full separation in the mid-part of the stroke, and in the mixed lubrication regime at the dead...

  15. BANACH CONTRACTION PRINCIPLE ON CONE RECTANGULAR METRIC SPACES

    Directory of Open Access Journals (Sweden)

    Ismat Beg

    2009-08-01

    Full Text Available We introduce the notion of cone rectangular metric space and prove {sc Banach} contraction mapping principle in cone rectangular metric space setting. Our result extends recent known results.

  16. A new analytic expression for fast calculation of the transient near and far field of a rectangular baffled piston.

    Science.gov (United States)

    Ortega, Alejandra; Tong, Ling; D'hooge, Jan

    2014-04-01

    Essential to (cardiac) 3D ultrasound are 2D matrix array transducer technology and the associated (two-stage) beam forming. Given the large number of degrees of freedom and the complexity of this problem, simulation tools play an important role. Hereto, the impulse response (IR) method is commonly used. Unfortunately, given the large element count of 2D array transducers, simulation times become significant jeopardizing the efficacy of the design process. The aim of this study was therefore to derive a new analytical expression to more efficiently calculate the IR in order to speed up the calculation process. To compare accuracy and computation time, the reference and the proposed method were implemented in MATLAB and contrasted. For all points of observation tested, the IR with both methods was identical. The mean calculation time however reduced in average by a factor of 3.93±0.03 times. The proposed IR method therefore speeds up the calculation time of the IR of an individual transducer element while remaining perfectly accurate. This new expression will be particularly relevant for 2D matrix transducer design where computation times remain currently a bottle neck in the design process. PMID:24447860

  17. Experimental Evaluation of the Free Piston Engine - Linear Alternator (FPLA).

    Energy Technology Data Exchange (ETDEWEB)

    Leick, Michael T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moses, Ronald W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    This report describes the experimental evaluation of a prototype free piston engine - linear alternator (FPLA) system developed at Sandia National Laboratories. The opposed piston design wa developed to investigate its potential for use in hybrid electric vehicles (HEVs). The system is mechanically simple with two - stroke uniflow scavenging for gas exchange and timed port fuel injection for fuel delivery, i.e. no complex valving. Electrical power is extracted from piston motion through linear alternators wh ich also provide a means for passive piston synchronization through electromagnetic coupling. In an HEV application, this electrical power would be used to charge the batteries. The engine - alternator system was designed, assembled and operated over a 2 - year period at Sandia National Laboratories in Livermore, CA. This report primarily contains a description of the as - built system, modifications to the system to enable better performance, and experimental results from start - up, motoring, and hydrogen combus tion tests.

  18. Dynamics of a massive piston in an ideal gas

    Energy Technology Data Exchange (ETDEWEB)

    Chernov, N I [University of Alabama at Birmingham, Birmingham, Alabama (United States); Lebowitz, J L [Rutgers, State University of New Jersey, New Brunswick, NJ (United States); Sinai, Yakov G [L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences, Moscow (Russian Federation)

    2002-12-31

    This survey is a study of a dynamical system consisting of a massive piston in a cubic container of large size L filled with an ideal gas. The piston has mass M{approx}L{sup 2} and undergoes elastic collisions with N{approx}L{sup 3} non-interacting gas particles of mass m=1. It is found that under suitable initial conditions there is a scaling regime with time and space scaled by L in which the motion of the piston and the one-particle distribution of the gas satisfy autonomous coupled equations (hydrodynamic equations) such that in the limit L{yields}{infinity} the mechanical trajectory of the piston converges in probability to the solution of the hydrodynamic equations for a certain period of time. There is also a heuristic discussion of the dynamics of the system on longer intervals of time.

  19. Turbocharger with sliding piston, and having vanes and leakage dams

    Science.gov (United States)

    Roberts, Quentin; Alnega, Ahmed

    2011-12-06

    A turbocharger having a sliding piston for regulating exhaust gas flow into the turbine wheel includes a set of first vanes mounted on a fixed first wall of the turbine nozzle and projecting axially toward an opposite second wall of the nozzle, and/or a set of second vanes mounted on the end of the piston and projecting in an opposite axial direction toward the first wall of the nozzle. For the/each set of vanes, there are leakage dams formed on the wall that is adjacent the vane tips when the piston is closed. The leakage dams are closely adjacent the vane tips and discourage exhaust gas from leaking in a generally radial direction past the vane tips as the piston just begins to open from its fully closed position.

  20. Design and Analysis of Piston Design for 4 Stroke Hero Bike Engine

    OpenAIRE

    Vinod Yadav; Dr. N.D. MITTAL

    2013-01-01

    Piston is the part of engine which convert heat and pressure energy liberated by fuel combustion into mechanical works. Engine piston is the most complex component among the automotives. This paper illustrate design procedure for a piston for 4 stroke petrol engine for hero bike and its analysis by its comparison with original piston dimensions used in bike. The design procedure involves determination of various piston dimensions using analytical method under maximum power condition. In this ...

  1. TECHNOLOGICAL PECULIARITIES OF PRODUCTION OF PISTONS FOR HIGH-POWERED ENGINES

    Directory of Open Access Journals (Sweden)

    M. A. Sadoha

    2009-01-01

    Full Text Available The paper present the results obtained when investigating fabrication of castings for pistons of high-augmented diesel internal combustion engine. The optimum casting parameter ranges are determined. The development is made of piston construction with combined insert that ensures production of castings of high-loaded pistons with a cavity (gallery for oil cooling of upper piston ring zone and enhancement of installation zone of upper piston ring.

  2. The bending of rectangular weakened by a vertical crack

    OpenAIRE

    Babloyan A.H.; Baghdasaryan A.V.

    2008-01-01

    The solution of a problem of elasticity theory for rectangular weakened by a centrally located vertical crack is brought. On the horizontal sides of the rectangular and on the crack faces the stresses are given. On the vertical sides of the rectangular three types of boundary conditions are given.

  3. g-Weak Contraction in Ordered Cone Rectangular Metric Spaces

    Directory of Open Access Journals (Sweden)

    S. K. Malhotra

    2013-01-01

    Full Text Available We prove some common fixed-point theorems for the ordered g-weak contractions in cone rectangular metric spaces without assuming the normality of cone. Our results generalize some recent results from cone metric and cone rectangular metric spaces into ordered cone rectangular metric spaces. Examples are provided which illustrate the results.

  4. Structural design of Stirling engine with free pistons

    Science.gov (United States)

    Matusov, Jozef; Gavlas, Stanislav; Malcho, Milan

    2014-08-01

    Stirling engine is a device that converts thermal energy to mechanical work, which is mostly used to drive a generator of electricity. Advantage of Stirling engine is that it works with closed-cycle, where working medium is regularly cooled and heated, which acts on the working piston. This engine can be made in three modifications - alpha, beta, gamma. This paper discusses the design of the gamma Stirling engine with free pistons.

  5. A contribution to film coefficient estimation in piston cooling galleries

    Energy Technology Data Exchange (ETDEWEB)

    Torregrosa, A.J.; Broatch, A.; Olmeda, P.; Martin, J. [CMT-Motores Termicos, Universidad Politecnica de Valencia, Aptdo. 22012, E-46071 Valencia (Spain)

    2010-02-15

    The need to reduce fuel consumption and exhaust emissions in internal combustion engines has been drastically increased during last years. One of the most important processes affecting these parameters is heat transfer from the in-cylinder gas to the surrounding walls, as this mechanism has a direct influence on the combustion process. Regarding the different walls (liner, cylinder head and piston surfaces), heat flow to the piston is especially important, as it is essential to avoid excessively high temperatures that could result in material damage and/or oil cracking. With this purpose different cooling strategies are used, among which the improvement of the piston cooling system by using oil galleries is preferred. In this work, the heat flow through the oil gallery in a Diesel piston was investigated on a dedicated test bench. This bench consists of a controlled heat source and a piston oil cooling system in which different test conditions were evaluated in order to obtain a correlation for the film coefficient associated with piston oil cooling. These experimental results were then incorporated into a lumped model for engine heat transfer. Finally, in order to evaluate the accuracy of this model and the effects of the correlation for oil gallery coefficient on engine heat flows, results obtained on a conventional engine test bench equipped with a Diesel engine, in which two piston temperatures had been measured, were used. The results show an improvement in piston temperature predictions when compared with those obtained using a previously reported expression for the calculation of the oil film coefficient. (author)

  6. Method Evaluating the Durability of Aircraft Piston Engines

    OpenAIRE

    Luca PIANCASTELLI; Leonardo FRIZZIERO; Eugenio MORGANTI; Eugenio PEZZUTI

    2012-01-01

    A significant issue in aircraft engines is quantifying residual life to overhaul. The algorithm described in this paper calculates with a good level of reliability the residual life of a petrol piston engine. The method was tested on small, latest-generation, naturally-aspirated aircraft and racing piston engines, and has been effective in several experiments. This method is implemented directly on the electronic control system of the engine with very few lines of C-code. The method can also ...

  7. Ensuring Steady Operation of Free-Piston Generator

    Directory of Open Access Journals (Sweden)

    Pavel Nemecek

    2006-02-01

    Full Text Available This paper describes Free-Piston Generator (FPG model and its control for achieving steady operation. A FPG is a special type of combustion engine representing a new approach concerning the conversion of the chemical energy of hydrocarbon fuel into electrical energy. Unlike conventional engines, this type of engine does not use a crankshaft, and generates electric energy directly by a linear movement of pistons.

  8. Electromagnetic liquid pistons for capillarity-based pumping.

    Science.gov (United States)

    Malouin, Bernard A; Vogel, Michael J; Olles, Joseph D; Cheng, Lili; Hirsa, Amir H

    2011-02-01

    The small scales associated with lab-on-a-chip technologies lend themselves well to capillarity-dominated phenomena. We demonstrate a new capillarity-dominated system where two adjoining ferrofluid droplets can behave as an electronically-controlled oscillator or switch by an appropriate balance of magnetic, capillary, and inertial forces. Their oscillatory motion can be exploited to displace a surrounding liquid (akin to an axial piston pump), forming electromagnetic "liquid pistons." Such ferrofluid pistons can pump a precise volume of liquid via finely tunable amplitudes (cf. pump stroke) or resonant frequencies (cf. pump speed) with no solid moving parts for long-term operation without wear in a small device. Furthermore, the rapid propagation of electromagnetic fields and the favorable scaling of capillary forces with size permit micron sized devices with very fast operating speeds (∼kHz). The pumping dynamics and performance of these liquid pistons is explored, with experimental measurements showing good agreement with a spherical cap model. While these liquid pistons may find numerous applications in micro- and mesoscale fluidic devices (e.g., remotely activated drug delivery), here we demonstrate the use of these liquid pistons in capillarity-dominated systems for chip-level, fast-acting adaptive liquid lenses with nearly perfect spherical interfaces.

  9. The problems of piston skirt microgeometry in combustion engines

    Science.gov (United States)

    Iskra, A.; Babiak, M.; Wróblewski, E.

    2016-09-01

    Geometry of the slot between piston bearing surface and cylinder bore affects the friction losses of the IC engine to the far extent. It appears that these losses depend more on the area covered with oil than the thickness of oil layer separating collaborating parts. Barrel-shaped or stepwise piston bearing surface is the way to reduce the oil covered area. Turns out that the referred to friction losses contributes more to area covered by the oil film than the film thickness of the separation elements cooperating. The method to reduce the area covered by the oil film is a modification of the bearing surface of the piston by adjusting the profile. This paper presents the results of simulation leading to the reduction in friction losses and abrasive wear of piston bearing surface and cylinder bore. Covering the piston bearing surface with a thin layer of graphite one can get an extremely advantageous tribological properties of the piston assembly which means the expected parameters of oil film and in a case of film rupture-an ignorable abrasive wear of the graphite layer and/or cylinder bore.

  10. Half-width at half-maximum, full-width at half-maximum analysis for resolution of asymmetrically apodized optical systems with slit apertures

    Indian Academy of Sciences (India)

    Andra Naresh Kumar Reddy; Dasari Karuna Sagar

    2015-01-01

    Resolution for the modified point spread function (PSF) of asymmetrically apodized optical systems has been analysed by a new parameter half-width at half-maximum (HWHM) in addition to the well-defined parameter full-width at half-maximum (FWHM). The distribution of half-maximum energy in the centroid of modified PSF has been investigated in terms of HWHM on good side and HWHM on bad side. We observed that as the asymmetry in PSF increases, FWHM of the main peak increases and then decreases and is being aided by the degree of amplitude apodization in the central region of slit functions. In the present study, HWHM (half-width at half-maximum) of the resultant PSF has been defined to characterize the resolution of the detection system. It is essentially a line of projection, which measures the width of the main lobe at its half-maximum position from the diffraction centre and has been computed for various amplitudes and antiphase apodizations of the slit aperture. We have noticed that HWHM on the good side decreases at the cost of the increased HWHM on the bad side in the presence of asymmetric apodization.

  11. Metamaterial Embedded Wearable Rectangular Microstrip Patch Antenna

    Directory of Open Access Journals (Sweden)

    J. G. Joshi

    2012-01-01

    Full Text Available This paper presents an indigenous low-cost metamaterial embedded wearable rectangular microstrip patch antenna using polyester substrate for IEEE 802.11a WLAN applications. The proposed antenna resonates at 5.10 GHz with a bandwidth and gain of 97 MHz and 4.92 dBi, respectively. The electrical size of this antenna is 0.254λ×0.5λ. The slots are cut in rectangular patch to reduce the bending effect. This leads to mismatch the impedance at WLAN frequency band; hence, a metamaterial square SRR is embedded inside the slot. A prototype antenna has been fabricated and tested, and the measured results are presented in this paper. The simulated and measured results of the proposed antenna are found to be in good agreement. The bending effect on the performance of this antenna is experimentally verified.

  12. Anisotropic rectangular metric for polygonal surface remeshing

    KAUST Repository

    Pellenard, Bertrand

    2013-06-18

    We propose a new method for anisotropic polygonal surface remeshing. Our algorithm takes as input a surface triangle mesh. An anisotropic rectangular metric, defined at each triangle facet of the input mesh, is derived from both a user-specified normal-based tolerance error and the requirement to favor rectangle-shaped polygons. Our algorithm uses a greedy optimization procedure that adds, deletes and relocates generators so as to match two criteria related to partitioning and conformity.

  13. On rectangular HOMFLY for twist knots

    CERN Document Server

    Kononov, Ya

    2016-01-01

    As a new step in the study of rectangularly-colored knot polynomials, we reformulate the prescription of arXiv:1606.06015 for twist knots in the double-column representations $R=[rr]$ in terms of skew Schur polynomials. These, however, are mysteriously shifted from the standard topological locus, what makes further generalization to arbitrary $R=[r^s]$ not quite straightforward.

  14. Design Analysis and Optimization of Internal Combustion Engine Piston using CAE tool ANSYS

    Directory of Open Access Journals (Sweden)

    Aditya Kumar Gupta

    2014-11-01

    Full Text Available In the internal combustion engine there are many reciprocating parts which are responsible for giving the motion to the engine. from them the piston is very important part of the internal combustion engine.. The working condition of the piston is so worst in comparison of other parts of the internal combustion engine. There is very high probability to failure of the piston due to high wear and tear. So there is necessary to inspection the working condition of piston. In before there is no availability of software packages. So there is difficult to check out the failure of the piston, it is also very time taken process. In now days the software packages are used to consume less time and give quality assurance. In this study work there are two steps of analysis of the piston they are Designing and Analysis. Firstly design the model of the piston in giving design specification on the modelling software like INVENTOR . Then giving it the constraints which are act on the working condition of the piston after import the model of the piston into the analysis software ANSYS in IGES format. Then the analysis become completed on the different parameters(temperature, stress, deformation and easily analysis the result. In this work the piston become optimized after the reducing the material of the piston. the mass and volume of the piston become reduced. The deformation also increased after the optimization which is responsible for the stress distribution on the piston head or piston crown.

  15. Buckling analysis of rectangular composite plates with rectangular cutout subjected to linearly varying in-plane loading using fem

    Indian Academy of Sciences (India)

    A Lakshmi Narayana; Krishnamohana Rao; R Vijaya Kumar

    2014-06-01

    A numerical study is carried out using finite element method, to examine the effects of square and rectangular cutout on the buckling behavior of a sixteen ply quasi-isotropic graphite/epoxy symmetrically laminated rectangular composite plate $[0^\\circ /+45^\\circ /-45^\\circ /90^\\circ ]_{2s}$, subjected to various linearly varying in-plane compressive loads. Further, this paper addresses the effects of size of square/rectangular cutout, orientation of square/rectangular cutout, plate aspect ratio(a/b), plate length/thickness ratio(a/t), boundary conditions on the buckling bahaviour of symmetrically laminated rectangular composite plates subjected to various linearly varying in-plane compressive loading. It is observed that the various linearly varying in-plane loads and boundary conditions have a substantial influence on buckling strength of rectangular composite plate with square/rectangular cutout.

  16. Instantaneous heat flux flowing into piston top-land surface of D.I. diesel engine; DI diesel kikan no piston top land bu eno shunji netsuryusoku

    Energy Technology Data Exchange (ETDEWEB)

    Taguma, M. [Zexel Corp., Tokyo (Japan); Inui, M.; Enomoto, Y.; Hagihara, Y. [Musashi Institute of Technology, Tokyo (Japan); Koyama, T. [Mitsubishi Motors Co., Tokyo (Japan)

    1997-10-01

    The thermal loads of the piston top-land surface in D.I. diesel engine during actual operation is not cleared. The authors fixed thin film thermocouples in the top-land center of a standard piston, and measured the instantaneous heat fluxes in that place. As a result, the authors made clear the thermal loads of the piston top-land surface in a cycle, and confirmed presence of the flame inflow to the piston top-land center. In addition, the authors made clear the thermal loads of the piston top-land surface in EGR operation. 4 refs., 8 figs.

  17. Theoretical Analysis of Noise of Piston Knocking Cylinder Wall in Automotive Engines

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Based on the loading conditions of engine, applying difference method to solve the hydrodynamic lubrication equation of piston skirt movement, the force acting on piston skirt and the moment on wrist pin were obtained. A computer program for simulating the piston second order motion was conducted to calculate the lateral motion of the upper part and the bottom part of piston skirts of the engine of automotive model CA1091. From the simulated result, the maximal impacting phase and the maximal impacting region of the piston were obtained. The result can be used for designing engine, diagnosing the noise of piston knocking cylinder wall and explaining many practical fault phenomena in theory.

  18. Transtibial prosthetic suspension: Less pistoning versus easy donning and doffing

    Directory of Open Access Journals (Sweden)

    Hossein Gholizadeh, MEngSc

    2012-12-01

    Full Text Available Poor suspension increases slippage of the residual limb inside the socket during ambulation. The main purpose of this article is to evaluate the pistoning at the prosthetic liner-socket interface during gait and assess patients’ satisfaction with two different liners. Two prostheses with seal-in and locking liners were fabricated for each of the 10 subjects with transtibial amputation. The Vicon motion system was used to measure the pistoning during gait. The subjects were also asked to complete a Prosthesis Evaluation Questionnaire. The results revealed higher pistoning inside the socket during gait with the locking liner than with the seal-in liner (p < 0.05. The overall satisfaction with the locking liner was higher (p < 0.05 because of the relative ease with which the patients could don and doff the device. As such, pistoning may not be the main factor that determines patients’ overall satisfaction with the prosthesis and other factors may also contribute to comfort and satisfaction with prostheses. The article also verifies the feasibility of the Vicon motion system for measuring pistoning during gait.

  19. Numerical analysis of the harmonic components of the Bragg wavelength content in spectral responses of apodized fiber Bragg gratings written by means of a phase mask with a variable phase step height.

    Science.gov (United States)

    Osuch, Tomasz

    2016-02-01

    The influence of the complex interference patterns created by a phase mask with variable diffraction efficiency in apodized fiber Bragg grating (FBGs) formation on their reflectance spectra is studied. The effect of the significant contributions of the zeroth and higher (m>±1) diffraction orders on the Bragg wavelength peak and its harmonic components is analyzed numerically. The results obtained for Gaussian and tanh apodization profiles are compared with similar data calculated for a uniform grating. It is demonstrated that when an apodized FBG is written using a phase mask with variable diffraction efficiency, significant enhancement of the harmonic components and a reduction of the Bragg wavelength peak in the grating spectral response are observed. This is particularly noticeable for the Gaussian apodization profile due to the substantial contributions of phase mask sections with relatively small phase steps in the FBG formation. PMID:26831768

  20. Demagnetizing effects in stacked rectangular prisms

    DEFF Research Database (Denmark)

    Christensen, Dennis; Nielsen, Kaspar Kirstein; Bahl, Christian Robert Haffenden;

    2011-01-01

    configuration, temperature distribution and applied magnetic field. In this paper the model is applied to the case of a stack of parallel, ferromagnetic rectangular prisms and the resulting internal field is found as a function of the orientation of the applied field, the number of prisms in the stack, the...... spacing between the prisms and the packing density of the stack. The results show that the resulting internal field is far from being equal to the applied field and that the various stack configurations investigated affect the resulting internal field significantly and non-linearly. The results have a...

  1. Shear Behavior of Rectangular Composite Lattice Structures

    OpenAIRE

    Hinds, Kirsten; Jensen, David

    2014-01-01

    The IsoBeam is a rectangular, unidirectional, composite lattice structure designed for beam applications. Three carbon fiber specimens each 2 ft (0.61 m) long, 6 in. (152.4 mm) tall and 3 in. (76.2 mm) wide with four 6 in. (152.4 mm) bays were hand-woven and tested in bending. The beams each weighed between 1.82-1.86 lbs (8.09-8.27 N). A low maximum strength was achieved, primarily due to insufficient consolidation and inadequate manufacturing quality but the structure is seen to be very duct...

  2. Recharge from rectangular areas to finite aquifers

    Science.gov (United States)

    Rao, N. H.; Sarma, P. B. S.

    1981-10-01

    A generalized analytical solution is derived for the growth of groundwater mound in finite aquifers bounded by open water bodies, in response to recharge from rectangular areas. Finite Fourier transforms are used to solve the linearized differential equation of groundwater flow. Unlike earlier solutions, the method presented here does not require the use of tables for evaluation of complicated functions. The solution is evaluated by comparison with existing numerical and analytical results. In stream-aquifer systems similar to those described above, application of the proposed solution is more realistic than using solutions available for infinite aquifers.

  3. Experimental Investigation of a Rectangular Airlift Pump

    OpenAIRE

    I. I. Esen

    2010-01-01

    Hydraulic performance of an airlift pump having a rectangular cross-section 20 mm × 80 mm was investigated through an experimental program. The pump was operated at six different submergence ratios and the liquid flow rate was measured at various flowrates of air injected. The effectiveness of the pump, defined as the ratio of the mass of liquid pumped to the mass of air injected, was determined as a function of the mass of air injected for different submergence ratios. Results obtained were ...

  4. RE-1000 free-piston Stirling engine update

    Science.gov (United States)

    Schreiber, J. G.

    1985-01-01

    A free piston Stirling engine was tested. The tests performed over the past several years on the single cylinder engine were designed to investigate the dynamics of a free piston Stirling engine. The data are intended to be used primarily for computer code validation. The tests designed to investigate the sensitivity of the engine performance to variations in working space pressure, heater and cooler temperatures, regenerator porosity, power piston mass and displacer dynamics were completed. In addition, some data were recorded with alternate working fluids. A novel resonant balance system for the engine was also tested. Some preliminary test results of the tests performed are presented along with an outline of future tests to be run with the engine coupled to a hydraulic output unit. A description of the hydraulic output unit is given.

  5. Lubrication and tribology in seawater hydraulic piston pump

    Institute of Scientific and Technical Information of China (English)

    WANG Dong; LI Zhuang-yun; ZHU Yu-quan

    2003-01-01

    Water hydraulic systems have provoked major interest because of the human friendly and environmental safety aspects. Piston pump is one of the most frequently used hydraulic units in recent engineering technique. In water hydraulic piston pump, poor lubrication is more likely to happen than in oil hydraulic one because of difference in properties between water and oil. So there are some key problems such as corrosive wear and erosion, which are investigated briefly. Many new materials have been developed, which give longer life expectancies with water without corrosion and erosion. A new type of seawater hydraulic piston pumps with better suction characteristics had been developed at HUST. Much of this research has concentrated on new materials, structure and experiments, which are also specially introduced.

  6. Numerical simulation of piston ring in the mixed lubrication

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Piston and piston ring lubrication is a factor that strongly affects the performance of thereciprocating internal combustion engine. When the oil film thickness becomes smaller than a cer-tain value, depending upon the roughness of the surfaces in contact, mixed lubrication has to beconsidered. This paper analyzes the lubrication of piston ring and predicts pressure distribution,lubricant film thickness and surface deformation. The work is based on a unified numerical ap-proach assuming that the pressure distribution obeys Reynolds equation in hydrodynamic lubrica-tion regions while in asperities contact regions, the contact pressure can be obtained through theso-called reduced Reynolds equation. The computation experience shows the unified equationsystem is stable and can deal with severe operating conditions.

  7. Metallographic study of laser thermal shock on a piston

    International Nuclear Information System (INIS)

    Experiments of thermal shock damage on a piston were conducted by a shaped high-power laser. The microstructure of thermal shock damaged specimen was characterized by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The mechanical properties of the thermal shock specimen were evaluated by microhardness and the corresponding damaged mechanisms were discussed. The results show that cracks originated from the interface of the Al-matrix and intermetallic phase due to the thermal and mechanical mismatch between the brittle components of the microstructure and the surrounding ductile matrix. Oxides of thermal shock crack can accelerate the damage of the piston. There exists a decline in the microhardness of the piston at all locations after thermal shock tests due to the comprehensive effects of the nonequilibrium distribution of the temperature and cooling method. (paper)

  8. CAD/CAM/CAI Application for High-Precision Machining of Internal Combustion Engine Pistons

    Directory of Open Access Journals (Sweden)

    V. V. Postnov

    2014-07-01

    Full Text Available CAD/CAM/CAI application solutions for internal combustion engine pistons machining was analyzed. Low-volume technology of internal combustion engine pistons production was proposed. Fixture for CNC turning center was designed.

  9. Lightweight piston-rod assembly for a reciprocating machine

    Energy Technology Data Exchange (ETDEWEB)

    Corey, John A. (North Troy, NY); Walsh, Michael M. (Schenectady, NY)

    1986-01-01

    In a reciprocating machine, there is provided a hollow piston including a dome portion on one end and a base portion on the opposite end. The base portion includes a central bore into which a rod is hermetically fixed in radial and angular alignment. The extending end of the rod has a reduced diameter portion adapted to fit into the central bore of a second member such as a cross-head assembly, and to be secured thereto in radial and axial alignment with the piston.

  10. Lightweight piston-rod assembly for a reciprocating machine

    Energy Technology Data Exchange (ETDEWEB)

    Corey, J.A.; Walsh, M.M.

    1986-06-10

    In a reciprocating machine, there is provided a hollow piston including a dome portion on one end and a base portion on the opposite end. The base portion includes a central bore into which a rod is hermetically fixed in radial and angular alignment. The extending end of the rod has a reduced diameter portion adapted to fit into the central bore of a second member such as a cross-head assembly, and to be secured thereto in radial and axial alignment with the piston. 4 figs.

  11. Experimental Study on the WavePiston Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Angelelli, E.

    This report presents the results of an experimental study of the power performance of the WavePiston wave energy converter. It focuses mainly on evaluating the power generating capabilities of the device and the effect of the following issues: Scaling ratios PTO loading Wave height and wave period...... dependency Oblique incoming waves Distance between plates During the study, the model supplied by the client, WavePiston, has been rigorously tested as all the anticipated tests have been done thoroughly and during all tests, good quality data has been obtained from all the sensors....

  12. Assembly for electrical conductivity measurements in the piston cylinder device

    Science.gov (United States)

    Watson, Heather Christine; Roberts, Jeffrey James

    2012-06-05

    An assembly apparatus for measurement of electrical conductivity or other properties of a sample in a piston cylinder device wherein pressure and heat are applied to the sample by the piston cylinder device. The assembly apparatus includes a body, a first electrode in the body, the first electrode operatively connected to the sample, a first electrical conductor connected to the first electrode, a washer constructed of a hard conducting material, the washer surrounding the first electrical conductor in the body, a second electrode in the body, the second electrode operatively connected to the sample, and a second electrical conductor connected to the second electrode.

  13. Experiments on the WavePiston, Wave Energy Converter

    DEFF Research Database (Denmark)

    Angelelli, E.; Zanuttigh, B.; Kofoed, Jens Peter;

    2011-01-01

    This paper analyses the performance of a new Wave Energy Converter (WEC) of the Oscillating Water Column type (OWC), named WavePiston. This near-shore floating device is composed of plates (i.e. energy collectors) sliding around a cylinder, that is placed perpendicular to the shore. Tests...... results and survivability considerations suggest that the WavePiston would be particularly suited for installations in milder seas. An example application is therefore presented in the Mediterranean Sea, off-shore the island of Sicily. In this case, each collector harvests the 10% of the available wave...

  14. Redesign of a Shock Absorber Piston Using Sintering

    OpenAIRE

    Kus, Ömer; Mojtabavi, Hamed

    2012-01-01

    The main objective of this report is to re-design of a product by substituting for another manufacturing process in order to get a cheaper product with the same function and quality. The current shock absorber piston is manufactured by the machining process at Öhlins Racing AB Company. Power Metallurgy (P/M) method could be a good substitute process to meet the technical requirements of the current piston with total lower cost. In this case, the whole process of product development gets invol...

  15. Homogeneous Charge Compression Ignition Free Piston Linear Alternator

    Energy Technology Data Exchange (ETDEWEB)

    Janson Wu; Nicholas Paradiso; Peter Van Blarigan; Scott Goldsborough

    1998-11-01

    An experimental and theoretical investigation of a homogeneous charge compression ignition (HCCI) free piston powered linear alternator has been conducted to determine if improvements can be made in the thermal and conversion efficiencies of modern electrical generator systems. Performance of a free piston engine was investigated using a rapid compression expansion machine and a full cycle thermodynamic model. Linear alternator performance was investigated with a computer model. In addition linear alternator testing and permanent magnet characterization hardware were developed. The development of the two-stroke cycle scavenging process has begun.

  16. The influence oil film lubrication of the piston-cylinder dynamic

    Directory of Open Access Journals (Sweden)

    Adriana Tokar

    2008-10-01

    Full Text Available An analytical study of the dynamics of a piston in a reciprocating engine was conducted. The equation of Reynolds and moving of piston are derived. The analysis, which incorporates a hydrodynamic lubrication model, was applied to M501 diesel engine. The results of this study indicate that piston dynamics were found to be sensitive to piston-cylinder bore clearance, location of the wrist pin and lubricant viscosity, underscoring their importance in engine design.

  17. STRESS ANALYSIS OF IC ENGINE PISTON FOR DIFFERENT MATERIAL AND PRESSURE LOAD USING FEA

    OpenAIRE

    Mr. Jadhav Vishal, Dr. R.K. Jain, Mr. Yogendra S.Chauhan

    2016-01-01

    This present work describes the stress distribution of two different aluminum alloys piston by using finite element method (FEM). The piston is designed for a single cylinder petrol engine using SOLIDWORKS 2013 software. The procedure for analytical design of two different aluminum alloy piston is described. Design is imported to ANSYS 15.0 software then static stress analysis is performed at different pressure load conditions on the piston. Results are presented and a comparison is made to f...

  18. 往复活塞压缩机的偏心活塞%Off-centre Piston in Reciprocator Piston Compressor

    Institute of Scientific and Technical Information of China (English)

    许大钊

    2011-01-01

    This article has given kinematical analytics and dynamical analytics for the off-centre piston in the crank link mechanism.According to the results of the theoretic analytics, the features and applications of the offcentre piston have been pointed out.%对偏心活塞的曲柄连杆机构进行运动分析和动力分析.根据理论分析的结果,提出了偏心活塞曲柄连杆机构的特点及其应用.

  19. Dual-wavelength single-longitudinal-mode erbium-doped fiber laser based on inverse-Gaussian apodized fiber Bragg grating and its application in microwave generation

    Science.gov (United States)

    Lin, Bo; Tjin, Swee Chuan; Zhang, Han; Tang, Dingyuan; Liang, Sheng; Hao, Jianzhong; Dong, Bo

    2011-03-01

    We propose a simple erbium-doped fiber ring laser. It consists of an inverse-Gaussian apodized fiber Bragg grating filter which has two ultra-narrow transmission bands, and an unpumped erbium-doped fiber as a saturable absorber. Stable dual-wavelength single-longitudinal-mode lasing with a wavelength separation of approximately 0.082 nm is achieved. A microwave signal at 10.502 GHz is demonstrated by beating the dual wavelengths at a photodetector.

  20. STUDY ON RECIPROCATING SEALS FOR A LARGER DIAMETER AXIAL PISTON

    Institute of Scientific and Technical Information of China (English)

    Yang Jian; Yang Huayong; Xu Bing

    2004-01-01

    Sealing performance of the reciprocating seals on a larger diameter (100 mm in diameter ) axial piston is theoretically investigated.Based on the characteristics of the clearance flow between the seal and the piston, reasonable boundary conditions for Navier-Stokes equations are determined and the equations are modified, so that the final equations can describe the real flow state of the clearance flow.Through combining the final equations with finite element method, the pressure distributions within the clearance field during the reciprocating motion of the piston and the leakage rate with the pressure are studied.The deflections of the seal which affect sealing performance are calculated as well.Sealing performance of piston seals using oil as the working liquid is compared with using water.It is concluded that the seal using water as the working liquid is under dry friction, which cannot be dealt with the theory of fluid mechanics.The seal structure is only acceptable using oil as the working liquid..

  1. ІNVESTIGATION OF PECULIARITIES OF PISTON RINGS LASER BORATING

    Directory of Open Access Journals (Sweden)

    BOLSHAKOV V. I.

    2015-11-01

    Full Text Available Problem formulation. Piston rings are subject to wear while in operation. Insufficient wear resistance of materials limits the growth of machines productivity as well as the terms of their exploitation. The required complex of properties of piston rings made of cast iron cannot be always reached by applying traditional methods of heat treatment or chemical heat treatment processing. Thus, application of traditional borating methods associated with diffusion of boron into the solid phase leads to the formation of the working layer exhibiting high brittleness. Therefore, the problem of increasing the wear resistance of piston rings without embrittlement is challenging. The use oflaser heating during borating provides the formation of a new layer with special properties. However, the optimum properties can be achieved only after determining the relationship between the parameters of running a process and the depth of the borated layer. Goal of research. To determine the influence of laser heating parameters on the depth of the borated layer, as the properties of piston rings depend on the depth of the latter. Conclusions. Increase in the speed of displacing parts during laser heating reduces the depth of the borated layer, and increase of the spot diameter enhances the depth of the layer. The phases and structural components of the borated layer were interpreted by means of X-ray and metallographic methods. The results of investigations can be applied to other machine parts, which are subject to intensive wear.

  2. Nonattacking Queens in a Rectangular Strip

    CERN Document Server

    Chaiken, Seth; Zaslavsky, Thomas; 10.1007/s00026-011-0068-7

    2011-01-01

    The function that counts the number of ways to place nonattacking identical chess or fairy chess pieces in a rectangular strip of fixed height and variable width, as a function of the width, is a piecewise polynomial which is eventually a polynomial and whose behavior can be described in some detail. We deduce this by converting the problem to one of counting lattice points outside an affinographic hyperplane arrangement, which Forge and Zaslavsky solved by means of weighted integral gain graphs. We extend their work by developing both generating functions and a detailed analysis of deletion and contraction for weighted integral gain graphs. For chess pieces we find the asymptotic probability that a random configuration is nonattacking, and we obtain exact counts of nonattacking configurations of small numbers of queens, bishops, knights, and nightriders.

  3. Physics from Angular Projection of Rectangular Grids

    CERN Document Server

    Singh, Ashmeet

    2015-01-01

    In this paper, we present a mathematical model for the angular projection of a rectangular arrangement of points in a grid. This simple, yet interesting problem, has both a scholarly value and applications for data extraction techniques to study the physics of various systems. Our work can interest undergraduate students to understand subtle points in the angular projection of a grid and describes various quantities of interest in the projection with completeness and sufficient rigour. We show that for certain angular ranges, the projection has non-distinctness, and calculate the details of such angles, and correspondingly, the number of distinct points and the total projected length. We focus on interesting trends obtained for the projected length of the grid elements and present a simple application of the model to determine the geometry of an unknown grid whose spatial extensions are known, using measurement of the grid projection at two angles only. Towards the end, our model is shown to have potential ap...

  4. Droplet size in a rectangular Venturi scrubber

    Directory of Open Access Journals (Sweden)

    M. A. M. Costa

    2004-06-01

    Full Text Available The Venturi scrubber is a device which uses liquid in the form of droplets to efficiently remove fine particulate matter from gaseous streams. Droplet size is of fundamental importance for the scrubber performance. In the present experimental study, a laser diffraction technique was used in order to measure droplet size in situ in a Venturi scrubber with a rectangular cross section. Droplet size distribution was measured as a function of gas velocity (58.3 to 74.9 m/s, liquid-to-gas ratio (0.07 to 0.27 l/m³, and distance from liquid injection point (64 to 173 mm. It was found that all these variables significantly affect droplet size. The results were compared with the predictions from correlations found in the literature.

  5. Rectangular Laser Resonators with Astigmatic Compensation

    DEFF Research Database (Denmark)

    Skettrup, Torben

    2005-01-01

    An investigation of rectangular resonators with a view to the compensation of astigmatism has been performed. In order to have beam waists placed at the same positions in the tangential and sagittal planes, pairs of equal mirrors were considered. It was found that at least two concave mirrors...... are necessary to obtain compensation. Four-concave-mirror systems are most stable close to the quadratic geometry, although the symmetric quadratic resonator itself cannot be compensated for astigmatism. Using four equal concave mirrors, compensation of astigmatism can be obtained in two arms at the same time....... Usually several stability ranges are found for four-mirror resonators with pair-wise equal mirrors, and it is possible with these systems to obtain small compensated beam waist radii suitable for frequency conversion. Relevant formulae are given and several relevant examples are shown using simulation...

  6. Deflection analysis of rectangular spatial coverage truss

    Directory of Open Access Journals (Sweden)

    M.N. Kirsanov

    2015-02-01

    Full Text Available An elastic spatial statically determinate truss of regular type, simulating the rectangular in plan coverage was considered. In the plane of the base the truss has two axes of symmetry. Four support structures (spherical hinge, cylindrical hinge and two vertical rods are located at its corners. An analytic solution was found for forces in the rods of the truss. Using the Maxwell-Mohr’s formula, the dependence of the deflection of the center was discovered in the truss under the influence of the concentrated force. There are five parameters of the problem in this formula: three linear dimensions, and the numbers of hinges on its lateral sides. To determine the desired patterns by means of the computer mathematics system Maple the recursion task by two parameters was solved. It was shown that dependence of the deflection on the number of panels and height of the truss detects a minimum, allowing optimizing the size of the structure.

  7. Method and structure for cache aware transposition via rectangular subsections

    Science.gov (United States)

    Gustavson, Fred Gehrung; Gunnels, John A

    2014-02-04

    A method and structure for transposing a rectangular matrix A in a computer includes subdividing the rectangular matrix A into one or more square submatrices and executing an in-place transposition for each of the square submatrices A.sub.ij.

  8. TRANSIENT THERMAL ANALYSIS OF INTERNAL COMBUSTION ENGINE PISTON IN ANSYS WORKBENCH BY FINITE ELEMENT METHOD

    OpenAIRE

    Vinay kumar attar*, Himanshu Arora , Shubham Sharma

    2016-01-01

    A piston is a component of reciprocating engines. Its purpose is to transfer force form expanding gas in the cylinder to the crank shaft via piston rod and a connecting rod. It is one of the most complex components of an automobile. In present, work a three dimensional solid model of piston including piston pin is designed  with the help of SOLIDWORKS software.The temperature, total heat flux are calculated to investigate factor of safety and life of the piston assembly using ANSYS workb...

  9. Inverse approach to determine piston profile from impact stress waveform on given non-uniform rod

    Institute of Scientific and Technical Information of China (English)

    朱萍玉; 刘德顺; 彭佑多; 陈安华

    2001-01-01

    An essential problem in the design of mechanical impact systems is the impact of a piston on a rod. The impact of a semi-finite cylindrical piston on a non-uniform rod was studied. Based on wave mechanics and characteristic line theory, an inverse numerical approach to determine the piston profile was proposed, by means of which the geometry of an impact piston may be determined from the given stress waveform for a given rod profile. Numerical results show that the given stress waveform may be produced by means of the alternatives of design of piston and rod. There is good agreement between the experimental results and numerical results.

  10. Design and Analysis of Piston Design for 4 Stroke Hero Bike Engine

    Directory of Open Access Journals (Sweden)

    Vinod Yadav

    2013-04-01

    Full Text Available Piston is the part of engine which convert heat and pressure energy liberated by fuel combustion into mechanical works. Engine piston is the most complex component among the automotives. This paper illustrate design procedure for a piston for 4 stroke petrol engine for hero bike and its analysis by its comparison with original piston dimensions used in bike. The design procedure involves determination of various piston dimensions using analytical method under maximum power condition. In this paper the combined effect of mechanical and thermal load is taken into consideration while determining various dimensions. The basic data of the engine are taken from a located engine type of hero bike.

  11. Experience with piston and piston rod seals for high pressure reciprocating compressors injecting natural gas on North Sea production platforms

    Energy Technology Data Exchange (ETDEWEB)

    Wison, R.S.

    1981-01-01

    The need to restrict flaring of associated natural gas has emphasized the importance of reliability of high-pressure reinjection compressors installed on certain North Sea platforms. This work reviews the contribution made by the development of piston and rod seals used on injection compressors, with reference to 3 important fields: Beryl, Statfjord, and Thistle.

  12. Assembly of piston and connecting rod in internal-combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, H.; Ozu, T.

    1987-01-13

    This patent describes an assembly of a piston and a connecting rod in an internal-combustion engine comprising: a generally cylindrical piston pin; a connecting rod integrally formed with and extending from only a lower surface of the piston pin at a point midway between either end of the piston pin; a piston having a skirt and a crown disposed on an upper surface of the skirt, the skirt having a concave bearing recess of semicylindrical shape on a lower surface thereof, the recess having a length at least equal so that of the piston pin; a metal bearing pieces of semicylindrical shape disposed in the concave bearing recess across the entire length thereof, an upper half of the piston pin being held in a semicylindrical recess defined by the metal bearing piece; a pair of space metal bearing halves of semicylindrical shape disposed, respectively, over a lower half of the piston pin on either side of the connecting rod; a pair of bearing caps, each of the bearing caps having a concave bearing recess, each of the bearing caps being fitted over one of the metal bearing halves to pivotally couple the piston pin to the piston; and bolt means fixedly attaching the pair of bearing caps to the skirt of the piston.

  13. Simulation of Thermal-Mechanical Strength for Marine Engine Piston Using FEA

    Directory of Open Access Journals (Sweden)

    Jiang Guo He

    2014-03-01

    Full Text Available Simulation of Thermal-Mechanical Strength for Marine Engine Piston Using FEA Abstract: This paper involves simulation of a 2-stroke 6S35ME marine diesel engine piston to determine its temperature field, thermal, mechanical and coupled thermal-mechanical stress. The distribution and magnitudes of the afore-mentioned strength parameters are useful in design, failure analysis and optimization of the engine piston. The piston model was developed in solid-works and imported into ANSYS for preprocessing, loading and post processing. Material model chosen was 10-node tetrahedral thermal solid 87. The simulation parameters used in this paper were piston material, combustion pressure, inertial effects and temperature. The highest calculated stress was the thermal-mechanical coupled stress and was below the yield stress of the piston material (580Mpa at elevated temperatures hence the piston would withstand the induced stresses during work cycles.

  14. NUMERICAL ANALYSIS OF STRIKE OF PISTON TO CYLINDER UNDER SUPERCHARGE CONDITIONS

    Institute of Scientific and Technical Information of China (English)

    余志壮; 宋正华; 董光能; 谢友柏

    2004-01-01

    Objective To investigate the changes to the strike extent of piston to cylinder after engine supercharge design. Methods The lubrication model between the skirt of piston and liner is established by means of piston dynamics, combined with the hydrodynamic lubrication equation. Optimized numerical analysis method is employed in solving the dynamics and lubrication equations. The analyses about piston strike under two combustion gas pressures are performed. Results The peak values of maximum eccentricity under supercharge condition are much greater than under non-supercharge condition, which means a stronger impulsion of piston to cylinder wall and a greater possibility of scuffing. The horizontal velocities of piston in supercharge condition are larger, which illuminate the more unstable motion state. Conclusion The analysis gives a new conclusion. Combustion gas pressure plays an important role in the piston strike motion. Influences of supercharge should be taken into account so that the traditional product test items can be improved.

  15. X-ray Zernike apodized photon sieves for phase-contrast microscopy%X射线相衬成像光子筛

    Institute of Scientific and Technical Information of China (English)

    程冠晓; 胡超

    2011-01-01

    基于Zernike相衬成像原理和光瞳切趾原理,提出一种将相位板和切趾光子筛集成为一个相衬显微物镜的X射线相衬成像光子筛的设计方法.这种X射线相衬成像物镜可以实现生物体组织或者其他弱吸收材料的高分辨率和高衬度成像.通过优化光子筛透镜的衍射结构,可以抑制成像系统的点扩展函数的旁瓣和消除高阶衍射焦点,从而提高成像分辨率;另外,将光子筛透镜和变相板合为一体,克服了成像透镜和变相板难以对准的缺陷.以高斯切趾光子筛为例,实验验证了设计方法的可行性.%We present a kind of diffractive lens Zernike apodized photon sieves (ZAPS) whose structure is based on the combination of two concepts:apodized photon sieves and Zernike phase-contrast.Combined with the synchrotron light source,the ZAPS can be used as an objective for high-resolution phase-contrast X-ray microscopy in physical and life sciences.The ZAPS is a single optic unit that integrates the appropriate ±π/2 radians phase shift through selective zone placement shifts in an apodized photon sieve.The focusing properties of the ZAPS can be easily controlled by apodizing its pupil function.An apodized photon sieve with Gaussian pupil is fabricated by lithographic technique and shows that the side-lobes are significantly suppressed at the expense of slightly widening the width of the main lobe.

  16. Liner surface improvements for low friction piston ring packs

    Science.gov (United States)

    Anderberg, C.; Dimkovski, Z.; Rosén, B.-G.

    2014-01-01

    The development of engine components in the automotive industry is governed by several constraints such as environmental legislation and customer expectations. About a half of the frictional losses in an internal combustion engine come from the interactions between the piston assembly and cylinder liner surface. The tribological considerations in the contact between the piston ring and cylinder liner have attracted much attention over the past few decades. Many non-conventional cylinder liner finishes have been, and are being, developed with the aim to reduce friction losses and oil consumption, but the effects of the surface finish on piston ring pack performance is not well understood. One way of reducing friction in the cylinder system is to reduce the tangential load from the piston ring pack, focusing on the oil control ring. However, the side-effect of this is a disappointingly increased oil consumption. In this study a number of different cylinder liner surface specifications were developed and implemented in test engines with the aim of maintaining the level for oil consumption when decreasing the tangential load for the piston ring pack. To improve our understanding of the result, the same surfaces were evaluated in elastic and elasto-plastic rough contact and hydrodynamic flow simulation models. It is shown that oil consumption is strongly related to surface texture on the cylinder liners and at lower speeds (900-1200 rpm), a ‘rougher surface’ with a high core (e.g. Sk) and valley roughness (e.g. Svk) results in higher oil consumption. At the medium speed range (1200-3600 rpm), oil consumption continues to dominate for the ‘rough’ surfaces but with a visible influence of a lower oil consumption for a decreased roughness within the ‘rough’ surface group. ‘Smooth’ surfaces with a ‘smooth’ core (Sk), irrespective of the valley component (Svk), show similar oil consumption. For engine speeds above 3600 rpms, an increase in plateau

  17. Gleason's Theorem for Rectangular JBW-Triples

    Science.gov (United States)

    Edwards, C. Martin; Rüttimann, Gottfried T.

    A JBW*-triple B is said to be rectangular if there exists a W*-algebra A and a pair (p,q) of centrally equivalent elements of the complete orthomodular lattice of projections in A such that B is isomorphic to the JBW*-triple pAq. Any weak*-closed injective operator space provides an example of a rectangular JBW*-triple. The principal order ideal of the complete *-lattice of centrally equivalent pairs of projections in a W*-algebra A, generated by (p,q), forms a complete lattice that is order isomorphic to the complete lattice of weak*-closed inner ideals in B and to the complete lattice of structural projections on B. Although not itself, in general, orthomodular, possesses a complementation that allows for definitions of orthogonality, centre, and central orthogonality to be given. A less familiar notion in lattice theory, that is well-known in the theory of Jordan algebras and Jordan triple systems, is that of rigid collinearity of a pair (e2,f2) and (e2,f2) of elements of . This is defined and characterized in terms of properties of . A W*-algebra A is sometimes thought of as providing a model for a statistical physical system. In this case B, or, equivalently, pAq, may be thought of as providing a model for a fixed sub-system of that represented by A. Therefore, may be considered to represent the set consisting of a particular kind of sub-system of that represented by pAq. Central orthogonality and rigid collinearity of pairs of elements of may be regarded as representing two different types of disjointness, the former, classical disjointness, and the latter, decoherence, of the two sub-systems. It is therefore natural to consider bounded measures m on that are additive on centrally orthogonal and rigidly collinear pairs of elements. Using results of J.D.M. Wright, it is shown that, provided that neither of the two hereditary sub-W*-algebras pAp and qAq of A has a weak*-closed ideal of Type I2, such measures are precisely those that are the restrictions of

  18. Externally heated valve engine a new approach to piston engines

    CERN Document Server

    Kazimierski, Zbyszko

    2016-01-01

    This book reports on a novel approach for generating mechanical energy from different, external heat sources using the body of a typical piston engine with valves. By presenting simple yet effective numerical models, the authors show how this new approach, which combines existing internal combustion technology with a lubrication system, is able to offer an economic solution to the problem of mechanical energy generation in piston engines. Their results also show that a stable heat generation process can be guaranteed outside of the engine. The book offers a detailed report on physical and numerical models of 4-stroke and 2-stroke versions of the EHVE together with different models of heat exchange, valves and results of their simulations. It also delivers the test results of an engine prototype run in laboratory conditions. By presenting a novel theoretical framework and providing readers with extensive knowledge of both the advantages and challenges of the method, this book is expected to inspire academic re...

  19. The problem of isotropic rectangular plate with four clamped edges

    Indian Academy of Sciences (India)

    C Erdem İmrak; Ismail Gerdemeli

    2007-06-01

    The examination of the exact solution of the governing equation of the rectangular plate is important for many reasons. This report discusses in exact solution of the governing equation of an isotropic rectangular plate with four clamped edges. A numerical method for clamped isotropic rectangular plate under distributed loads and an exact solution of the governing equation in terms of trigonometric and hyperbolic function are given. Finally, an illustrative example is given and the results are compared with those reported earlier. This method is found to be easier and effective. The results show reasonable agreement with other available results, but with a simpler and practical approach.

  20. Optimization of Multi-band Rectangular-Triangular Slotted Antenna

    Directory of Open Access Journals (Sweden)

    K.swetha,

    2015-03-01

    Full Text Available A multi-band microstrip patch antenna is developed and presented in this paper. The radiating elements in this antenna are composed of rectangular and triangular slots. These slots are engraved in the rectangular and triangular patch, joined together in one structure, and by single probe feed. The rectangular and triangular slots make the antenna to operate at multiband with relatively high gain. Therefore, this antenna can be used for wireless communication applications like WLAN, WiMax and radar system applications.

  1. Flow Characteristics of Rectangular Underexpanded Impinging Jets

    Institute of Scientific and Technical Information of China (English)

    Minoru YAGA; Yoshio KINJO; Masumi TAMASHIRO; Kenyu OYAKAWA

    2006-01-01

    In this paper, the flow fields of underexpanded impinging jet issued from rectangular nozzles of aspect ratio 1,3 and 5 are numerically and experimentally studied. Two dimensional temperature and pressure distributions are measured by using infrared camera and the combination of a pressure scanning device and a stepping motor, respectively. The variation of the stagnation pressure on the impinging plate reveals that a hystcretic phenomenon exists during the increasing and decreasing of the pressure ratio for the aspect ratio of 3.0 and 5.0. It is also found that the nozzle of aspect ratio 1.0 caused the largest total pressure loss pc/p0 = 0.27 at the pressure ratio of p0/pb, = 6.5, where pc is the stagnation center pressure on the wall, p0 the upstream stagnation pressure, pb the ambient pressure. The other two nozzles showed that the pressure loss pc / p0=0.52 and 0.55 were achieved by the nozzles of the aspect ratio 3,0 and 5.0, respectively. The comparison between the calculations and experiments is fairly good, showing the three dimensional streamlines and structures of the shock waves in the jets. However, the hysteresis of the pressure variations observed in the experiments between the pressure ratio of 3.5 and 4.5 cannot be confirmed in the calculations.

  2. The hydrodynamic focusing effect inside rectangular microchannels

    Science.gov (United States)

    Lee, Gwo-Bin; Chang, Chih-Chang; Huang, Sung-Bin; Yang, Ruey-Jen

    2006-05-01

    This paper presents a theoretical and experimental investigation into the hydrodynamic focusing effect in rectangular microchannels. Two theoretical models for two-dimensional hydrodynamic focusing are proposed. The first model predicts the width of the focused stream in symmetric hydrodynamic focusing in microchannels of various aspect ratios. The second model predicts the location and the width of the focused stream in asymmetric hydrodynamic focusing in microchannels with a low or high aspect ratio. In both models, the theoretical results are shown to be in good agreement with the experimental data. Hence, the models provide a useful means of performing a theoretical analysis of flow control in microfluidic devices using hydrodynamic focusing effects. The ability of the proposed models to control the focused stream within a micro flow cytometer is verified in a series of experimental trials performed using polystyrene microparticles with a diameter of 20 µm. The experimental data show that the width of the focused stream can be reduced to the same order of magnitude as that of the particle size. Furthermore, it is shown that the microparticles can be successfully hydrodynamically focused and switched to the desired outlet port of the cytometer. Hence, the models presented in this study provide sufficient control to support cell/particle counting and sorting applications.

  3. Perceptual guidelines for creating rectangular treemaps.

    Science.gov (United States)

    Kong, Nicholas; Heer, Jeffrey; Agrawala, Maneesh

    2010-01-01

    Treemaps are space-filling visualizations that make efficient use of limited display space to depict large amounts of hierarchical data. Creating perceptually effective treemaps requires carefully managing a number of design parameters including the aspect ratio and luminance of rectangles. Moreover, treemaps encode values using area, which has been found to be less accurate than judgments of other visual encodings, such as length. We conduct a series of controlled experiments aimed at producing a set of design guidelines for creating effective rectangular treemaps. We find no evidence that luminance affects area judgments, but observe that aspect ratio does have an effect. Specifically, we find that the accuracy of area comparisons suffers when the compared rectangles have extreme aspect ratios or when both are squares. Contrary to common assumptions, the optimal distribution of rectangle aspect ratios within a treemap should include non-squares, but should avoid extremes. We then compare treemaps with hierarchical bar chart displays to identify the data densities at which length-encoded bar charts become less effective than area-encoded treemaps. We report the transition points at which treemaps exhibit judgment accuracy on par with bar charts for both leaf and non-leaf tree nodes. We also find that even at relatively low data densities treemaps result in faster comparisons than bar charts. Based on these results, we present a set of guidelines for the effective use of treemaps and suggest alternate approaches for treemap layout. PMID:20975136

  4. Rectangular Diamond-Lined Accelerator Structure

    CERN Document Server

    Wang, Changbiao; Yakovlev, Vyacheslav P

    2005-01-01

    For high frequency accelerators with normal-conducting structures studied by the NLC/GLC collaboration and the CLIC group, rf breakdown is the main gradient limitation. In this paper, a Ka-band rectangular dielectric-lined structure is described as an attempt to increase accelerating gradient beyond the limits suitable for metallic structures. The structure is based on amorphous dielectrics that are known to exhibit high breakdown limits (~ GV/m). An example is artificial diamond that has already been successfully used on an industrial basis for large-diameter output windows of high power gyrotrons, and is produced industrially in increasing quantities. Artificial diamond has low loss tangent, moderate dielectric constant and high breakdown limit of ~2 GV/m. In the proposed structure diamond-slabs are employed to support high-gradient acceleration fields. Interposition of vacuum gaps between the dielectric slabs and the side walls is shown to reduce Ohmic losses substantially, leading to an increase in shunt ...

  5. FEA OF RECTANGULAR CUP DEEP DRAWING PROCESS

    Directory of Open Access Journals (Sweden)

    Awad D.S

    2012-08-01

    Full Text Available Deep drawing is a process for shaping flat sheets into cup shaped articles without fracture or excessive localized thinning. The complex deep drawing of thin metallic sheets is widely used during industrial material forming applications. It allows production of thin walled parts with complicated shapes such as automotive panels or structural parts. The process consists of the plastic deformation of an initial at blank subjected to the action of a rigid punch and die while constrained on the periphery by a blank holder. Conventional design processes for sheet metal forming are usually based on a empirical approach. However, due to the requirement of high precision and reliability in shaped parts, these methods are far away from a final and reliable solution. Nowadays, Finite Element Method (FEM is being gradually adopted by industry to envisage the formability properties of sheet metals. The design and control of a deep drawing process depends not only on the work piece material, but also on the condition at the tool work piece interface, the mechanics of plastic deformation and the equipment used. In this paper, rectangular cup component of EDDQ Steel and Mild Steel is simulated using HYPERMESH 11 by varying various process parameters.

  6. Epidemic Spreading in Random Rectangular Networks

    CERN Document Server

    Estrada, Ernesto; Moreno, Yamir

    2015-01-01

    Recently, Estrada and Sheerin (Phys. Rev. E 91, 042805 (2015)) developed the random rectangular graph (RRG) model to account for the spatial distribution of nodes in a network allowing the variation of the shape of the unit square commonly used in random geometric graphs (RGGs). Here, we consider an epidemics dynamics taking place on the nodes and edges of an RRG and we derive analytically a lower bound for the epidemic threshold for a Susceptible-Infected-Susceptible (SIS) or Susceptible-Infected-Recovered (SIR) model on these networks. Using extensive numerical simulations of the SIS dynamics we show that the lower bound found is very tight. We conclude that the elongation of the area in which the nodes are distributed makes the network more resilient to the propagation of an epidemics due to the fact that the epidemic threshold increases with the elongation of the rectangle. On the other hand, using the "classical" RGG for modeling epidemics on non-squared cities generates a larger error due to the effects...

  7. NEW DESIGN OF PISTON RODS SEALING UNIT OF STERLING ENGINE

    OpenAIRE

    Arapov, B.; Seytkazenova, K.; Seraliyev, G.

    2013-01-01

    The advantage of suggested design of sealing unit of Stirling engine actuating and displacing pistons is that due to supply to intergland space of medium with pressure half as large as average pressure of operating medium in working cylinder, pressure head on separate gland seals is decreased two times. This results in increase of durability of gland seals two times and more. Fluoroplastic seal glands have thin lobes with inner cone hole accommodating the sealed rod and are fitted on them pre...

  8. Nonstationary heat flow in the piston of the turbocharged engine

    Directory of Open Access Journals (Sweden)

    Piotr GUSTOF

    2010-01-01

    Full Text Available In this study the numeric computations of nonstationary heat flow in form of temperature distribution on characteristic surfaces of the piston of the turbocharged engine at the beginning phase its work was presented. The computations were performed for fragmentary load engine by means of the two-zone combustion model, the boundary conditions of III kind and the finite elements method (FEM by using of COSMOS/M program.

  9. Free piston variable-stroke linear-alternator generator

    Energy Technology Data Exchange (ETDEWEB)

    Haaland, C.M.

    1998-12-15

    A free-piston variable stroke linear-alternator AC power generator for a combustion engine is described. An alternator mechanism and oscillator system generates AC current. The oscillation system includes two oscillation devices each having a combustion cylinder and a flying turnbuckle. The flying turnbuckle moves in accordance with the oscillation device. The alternator system is a linear alternator coupled between the two oscillation devices by a slotted connecting rod. 8 figs.

  10. Free piston variable-stroke linear-alternator generator

    Energy Technology Data Exchange (ETDEWEB)

    Haaland, Carsten M. (Dadeville, AL)

    1998-01-01

    A free-piston variable stroke linear-alternator AC power generator for a combustion engine. An alternator mechanism and oscillator system generates AC current. The oscillation system includes two oscillation devices each having a combustion cylinder and a flying turnbuckle. The flying turnbuckle moves in accordance with the oscillation device. The alternator system is a linear alternator coupled between the two oscillation devices by a slotted connecting rod.

  11. An Approximate Solution for Spherical and Cylindrical Piston Problem

    Indian Academy of Sciences (India)

    S K Singh; V P Singh

    2000-02-01

    A new theory of shock dynamics (NTSD) has been derived in the form of a finite number of compatibility conditions along shock rays. It has been used to study the growth and decay of shock strengths for spherical and cylindrical pistons starting from a non-zero velocity. Further a weak shock theory has been derived using a simple perturbation method which admits an exact solution and also agrees with the classical decay laws for weak spherical and cylindrical shocks.

  12. Instantaneous engine frictional torque, its components and piston assembly friction

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, F.A. (ed.) (Argonne National Lab., IL (United States)); Henein, N.A. (Wayne State Univ., Detroit, MI (United States). Center for Automotive Research)

    1992-05-01

    The overall goal of this report is to document the work done to determine the instantaneous frictional torque of internal combustion engine by using a new approach known as (P-[omega]) method developed at Wayne State University. The emphasis has been to improve the accuracy of the method, and apply it to both diesel and gasoline engines under different operating conditions. Also work included an investigation to determine the effect of using advanced materials and techniques to coat the piston rings on the instantaneous engine frictional torque and the piston assembly friction. The errors in measuring the angular velocity, [omega], have been determined and found to be caused by variations in the divisions within one encoder, encoder-to-encoder variations, misalignment within the encoder itself and misalignment between the encoder and crankshaft. The errors in measuring the cylinder gas pressure, P, have been determined and found to be caused by transducer-to-transducer variations, zero drift, thermal stresses and lack of linearity. The ability of the (P-[omega]) method in determining the frictional torque of many engine components has been demonstrated. These components include valve train, fuel injection pump with and without fuel injection, and piston with and without different ring combinations. The emphasis in this part of the research program has been on the piston-ring assembly friction. The effects of load and other operating variables on IFT have been determined. The motoring test, which is widely used in industry to measure engine friction has been found to be inaccurate. The errors have been determined at different loads.

  13. The Holy Grail of variable compression within piston range; Le Graal de la compression variable a portee de piston

    Energy Technology Data Exchange (ETDEWEB)

    Boncquet, P.Y.

    2004-09-01

    A new concept of variable compression engine, developed by Viannet Rhabi from the company MCE-5, allows to adapt the compression ratio of an internal combustion engine (volume between the up and down positions of the piston) to the conditions of use of the vehicle. This system uses an intermediate part between the piston and the crank-shaft which acts like a lever and allows to change the compression ration from 7:1 to 17:1 in a very reactive and precise way. The efficiency gain of this system allows to save 5 to 7% of fuel. This system opens also the way to engines down-sizing with up to 30% of fuel saving results and without the self-ignition problem linked with turbo-charged down-sized engines. Short paper. (J.S.)

  14. On the Influence of Piston and Cylinder Density in Tribodynamics of a Radial Piston Digital Fluid Power Displacement Motor

    DEFF Research Database (Denmark)

    Johansen, Per; Roemer, Daniel Beck; Andersen, Torben O.;

    2015-01-01

    . In this paper the influence of the inertia term on the lubrication gaps of a radial piston motor are studied by a parametric analysis of the piston and cylinder density in a multibody tribodynamic simulation model. The motor is modeled as a digital fluid power displacement machine and a series of full......In the past three decades an increasing amount of research has been performed in the field of tribodynamics of fluid power pumps and motors. The main incentives for this research are optimization of reliability and eciency through the study of loss and wear mechanisms. These mechanisms are very......, such that solid body inertia is neglected. The other approach includes the inertia terms in the calculation of microdynamics. The inclusion of inertia terms entails a need for smaller time steps in comparison to the force balance approach, wherefore it is of interest to analyze the influence of the inertia term...

  15. A Multiple U Slotted Rectangular Micro-strip Patch Antenna

    Directory of Open Access Journals (Sweden)

    Anshul Shrivastava1 Abhinav Bhargava2 Samrat Ghosh3

    2012-11-01

    Full Text Available In this paper we present a proposed design for Rectangular micro-strip patch antenna by cutting five U shaped slots in the Rectangular patch. Using proposed antenna design and probe feeding at proper position we find the resultant return loss, VSWR and bandwidth. We are using IE3D simulation software for designing and analysis. We have observed that using slotted patch antenna and using probe feed at proper location we can get better return loss, VSWR and bandwidth.

  16. Generalized regularity and regularizability of rectangular descriptor systems

    Institute of Scientific and Technical Information of China (English)

    Guangren DUAN; Yan CHEN

    2007-01-01

    The notion of generalized regularity is proposed for rectangular descriptor systems. Generalized regularizability of a rectangular descriptor system via different feedback forms is considered. Necessary and sufficient conditions for generalized regularizability are obtained, which are only dependent upon the open-loop coefficient matrices. It is also shown that under these necessary and sufficient conditions, all the generalized regularizing feedback controllers form a Zarisky open set. A numerical example demonstrates the proposed results.

  17. Design of Rectangular Microstrip Antenna with Metamaterial for Increased Bandwidth

    OpenAIRE

    B R Koushik; B Ajeya

    2013-01-01

    In this paper a Rectangular Patch Antenna is specifically designed and analysed using metamaterial concepts. Based on an ordinary patch antenna, it has a double C shaped resonant structure embedded in the centre of the substrate of the Rectangular Patch Antenna. The resonant structure has a strong electric response in a certain frequency of interest, and can be used to construct metamaterials with negative permittivity. It is found the great impact on the antenna performance to modify the dim...

  18. A Rectangular Planar Spiral Antenna for GIS Partial Discharge Detection

    OpenAIRE

    Xiaoxing Zhang; Yefei Han; Wei Li; Xuetao Duan

    2014-01-01

    A rectangular planar spiral antenna sensor was designed for detecting the partial discharge in gas insulation substations (GIS). It can expediently receive electromagnetic waves leaked from basin-type insulators and can effectively suppress low frequency electromagnetic interference from the surrounding environment. Certain effective techniques such as rectangular spiral structure, bow-tie loading, and back cavity structure optimization during the antenna design process can miniaturize antenn...

  19. Consensus dynamics on random rectangular graphs

    Science.gov (United States)

    Estrada, Ernesto; Sheerin, Matthew

    2016-06-01

    A random rectangular graph (RRG) is a generalization of the random geometric graph (RGG) in which the nodes are embedded into a rectangle with side lengths a and b = 1 / a, instead of on a unit square [ 0 , 1 ] 2. Two nodes are then connected if and only if they are separated at a Euclidean distance smaller than or equal to a certain threshold radius r. When a = 1 the RRG is identical to the RGG. Here we apply the consensus dynamics model to the RRG. Our main result is a lower bound for the time of consensus, i.e., the time at which the network reaches a global consensus state. To prove this result we need first to find an upper bound for the algebraic connectivity of the RRG, i.e., the second smallest eigenvalue of the combinatorial Laplacian of the graph. This bound is based on a tight lower bound found for the graph diameter. Our results prove that as the rectangle in which the nodes are embedded becomes more elongated, the RRG becomes a 'large-world', i.e., the diameter grows to infinity, and a poorly-connected graph, i.e., the algebraic connectivity decays to zero. The main consequence of these findings is the proof that the time of consensus in RRGs grows to infinity as the rectangle becomes more elongated. In closing, consensus dynamics in RRGs strongly depend on the geometric characteristics of the embedding space, and reaching the consensus state becomes more difficult as the rectangle is more elongated.

  20. Design, Analysis and Optimization of Three Aluminium Piston Alloys Using FEA

    Directory of Open Access Journals (Sweden)

    Ajay Raj Singh

    2014-01-01

    Full Text Available This paper describes the stress distribution and thermal stresses of three different aluminum alloys piston by using finite element method (FEM. The parameters used for the simulation are operating gas pressure, temperature and material properties of piston. The specifications used for the study of these pistons belong to four stroke single cylinder engine of Bajaj Kawasaki motorcycle. This paper illustrates the procedure for analytical design of three aluminum alloy pistons using specifications of four stroke single cylinder engine of Bajaj Kawasaki motorcycle. The results predict the maximum stress and critical region on the different aluminum alloy pistons using FEA. It is important to locate the critical area of concentrated stress for appropriate modifications. Static and thermal stress analysis is performed by using ANSYS 12.1. The best aluminum alloy material is selected based on stress analysis results. The analysis results are used to optimize piston geometry of best aluminum alloy.

  1. Development of a Collins-type cryocooler floating piston control algorithm

    Science.gov (United States)

    Hogan, Jake; Hannon, Charles L.; Brisson, John

    2012-06-01

    The Collins-type cryocooler uses a floating piston design for the working fluid expansion. The piston floats between a cold volume, where the working fluid is expanded, and a warm volume. The piston is shuttled between opposite ends of the closed cylinder by opening and closing valves connecting several reservoirs at various pressures to the warm volume. Ideally, these pressures should be distributed between the high and low system pressure to gain good control of the piston motion. In this work, a numerical quasi-steady thermodynamic model is developed for the piston cycle. The model determines the steady state pressure distribution of the reservoirs for a given control algorithm. The results are then extended to show how valve timing modifications can be used to overcome helium leakage past the piston during operation.

  2. a Simple Model to Estimate the Impact Force Induced by Piston Slap

    Science.gov (United States)

    CHO, S.-H.; AHN, S.-T.; KIM, Y.-H.

    2002-08-01

    The dynamics of piston's secondary motion (lateral and rotational motion) across the clearance between piston and cylinder inner wall of reciprocating machines are analyzed. This paper presents an analytical model, which can predict the impact forces and vibratory response of engine block surface induced by the piston slap of an internal combustion engine. A piston is modelled on a three-degree-of-freedom system to represent its planar motion. When slap occurs, the impact point between piston skirt and cylinder inner wall is modelled on a two-degree-of-freedom vibratory system. The equivalent parameters such as mass, spring constant, and damping constant of piston and cylinder inner wall are estimated by using measured (driving) point mobility. Those parameters are used to calculate the impact force and for estimating the vibration level of engine block surfaces. The predicted results are compared with experimental results to verify the model.

  3. Diffraction radiation from a charged particle moving through a rectangular hole in a rectangular screen

    International Nuclear Information System (INIS)

    We developed a new model for calculating diffraction radiation (DR) from an electron moving through a rectangular hole in a rectangular screen. The calculations show that short wavelength DR is very sensitive to the beam size. For example, optical DR (ODR) could be used to measure the beam size as small as 10 μm. Moreover, splitting two polarization components it becomes possible to measure vertical and horizontal beam sizes independently. We have calculated the DR spectra and compared them with TR ones for a finite size target. It is shown that when the DR wavelength is comparable with or longer than the hole size, the photon yield is mostly determined by the outer target dimensions. It means that in case transversal beam dimensions smaller than the observation wavelength the coherent DR could be used for non-invasive bunch length measurements with the same accuracy as the coherent TR techniques. However, the outer target dimensions must be taken into account because the finite target size causes a significant intensity suppression in the long wavelength spectral range as well as distortion of the coherent spectrum

  4. Passive Control of Supersonic Rectangular Jets through Boundary Layer Swirl

    Science.gov (United States)

    Han, Sang Yeop; Taghavi, Ray R.; Farokhi, Saeed

    2013-06-01

    Mixing characteristics of under-expanded supersonic jets emerging from plane and notched rectangular nozzles are computationally studied using nozzle exit boundary layer swirl as a mean of passive flow control. The coupling of the rectangular jet instability modes, such as flapping, and the swirl is investigated. A three-dimensional unsteady Reynolds-Averaged Navier-Stokes (RANS) code with shock adaptive grids is utilized. For plane rectangular nozzle with boundary layer swirl, the flapping and spanwise oscillations are captured in the jet's small and large dimensions at twice the frequencies of the nozzles without swirl. A symmetrical oscillatory mode is also observed in the jet with double the frequency of spanwise oscillation mode. For the notched rectangular nozzle with boundary layer swirl, the flapping oscillation in the small jet dimension and the spanwise oscillation in the large jet dimension are observed at the same frequency as those without boundary layer swirl. The mass flow rates in jets at 11 and 8 nozzle heights downstream of the nozzles increased by nearly 25% and 41% for the plane and notched rectangular nozzles respectively, due to swirl. The axial gross thrust penalty due to induced swirl was 5.1% for the plane and 4.9% for the notched rectangular nozzle.

  5. ANALYTIC EXPRESSION OF MAGNETIC FIELD DISTRIBUTION OF RECTANGULAR PERMANENT MAGNETS

    Institute of Scientific and Technical Information of China (English)

    苟晓凡; 杨勇; 郑晓静

    2004-01-01

    From the molecular current viewpoint,an analytic expression exactly describing magnetic field distribution of rectangular permanent magnets magnetized sufficiently in one direction was derived from the Biot-Savart's law. This expression is useful not only for the case of one rectangular permanent magnet bulk, but also for that of several rectangular permanent magnet bulks. By using this expression,the relations between magnetic field distribution and the size of rectangular permanent magnets as well as the magnitude of magnetic field and the distance from the point in the space to the top (or bottom) surface of rectangular permanent magnets were discussed in detail. All the calculating results are consistent with experimental ones. For transverse magnetic field which is a main magnetic field of rectangular permanent magnets,in order to describe its distribution,two quantities,one is the uniformity in magnitude and the other is the uniformity in distribution of magnetic field,were defined. Furthermore, the relations between them and the geometric size of the magnet as well as the distance from the surface of permanent magnets were investigated by these formulas. The numerical results show that the geometric size and the distance have a visible influence on the uniformity in magnitude and the uniformity in distribution of the magnetic field.

  6. Apodized-aperture pixel design to increase high-frequency DQE and reduce noise aliasing in x-ray detectors

    Science.gov (United States)

    Ismailova, Elina; Karim, Karim; Cunningham, Ian A.

    2015-03-01

    The detective quantum efficiency (DQE) of an x-ray detector, expressed as a function of spatial frequency, describes the ability to produce high-quality images relative to an ideal detector. While the DQE normally decreases substantially with increasing frequency, we describe an approach that can be used to improve the DQE response by increasing the DQE at high spatial frequencies. The approach makes use of an apodized-aperture pixel (AAP) design that requires use of a high-resolution x-ray converter such as selenium coupled to a sensor array with very small physical sensor elements, such as CMOS sensors. While sensors with elements of 10 - 25 μm are too small for most practical applications in medical radiography, we describe how larger image pixels of a practical size can be synthesized to provide a better DQE than simple binning or using physical pixels of the same size. A theoretical cascaded-systems analysis shows the DQE at the image sampling cut-off frequency can be improved by up to a factor of 2.5x. The AAP approach was validated experimentally using a CMOS/CsI-based detector having 0.05-mm sensor elements. Using AAP images with 0.2-mm pixels, the high-frequency DQE value was increased from 0.2 to 0.4 compared to simple 4x4 binning. It is concluded that ultra-high-resolution sensors can be used to optimize the high-frequency performance of x-ray detectors and make substantial improvements in image quality for visualization of small stuctures and fine image detail in comparison to current imaging systems.

  7. Comparison of visual outcomes after implantation of diffractive trifocal toric intraocular lens and a diffractive apodized bifocal toric intraocular lens

    Science.gov (United States)

    Gundersen, Kjell Gunnar; Potvin, Rick

    2016-01-01

    Purpose The aim of this study was to compare a new diffractive trifocal toric lens with an apodized diffractive bifocal toric lens in terms of refractive and visual acuity (VA) outcomes, including low-contrast VA (LCVA), as well as the patient’s visual function 3 months after implantation. Patients and methods This is a randomized prospective study involving bilateral implantation of a trifocal toric or a bifocal toric lens. At 3 months postoperatively, the subject’s vision was tested both uncorrected and with his/her best distance correction at: distance (4 m), intermediate (63 cm), and near (40 cm). Binocular defocus curves were measured with no correction and with the subject’s best distance correction in place. Quality of vision was measured using the National Eye Institute Visual Function Questionnaire. Results A total of 22 patients were enrolled (eleven in each group). There was no statistically significant difference in the absolute change in measured rotation between 1 month and 3 months postoperatively between the two intraocular lens (IOL) groups (P=0.98). At 3 months, the postoperative refraction and distance VA by eye were similar between groups. There was no statistically significant difference in the measured LCVA between groups (P=0.39). The defocus curve showed that at 67 cm, the trifocal toric lens had statistically significantly better VA when compared to the bifocal toric lens. There were no statistically significant differences by group for any of the National Eye Institute Visual Function Questionnaire scores (P>0.26 in all cases). Conclusion The trifocal toric IOL improved the intermediate vision without negatively impacting visual function and distance, near, or low-contrast VA when compared to a bifocal toric IOL. The toric component of the trifocal lens effectively reduced astigmatism and provided good rotational stability. PMID:27051269

  8. Mixed Lubrication Analysis and Experiment Validation of Internal Combustion Piston Skirt

    Institute of Scientific and Technical Information of China (English)

    杨俊伟; 于旭东; 王成焘; 谢友柏

    2004-01-01

    A mixed lubrication model was established for piston skirt lubrication. The mathematical model developed in this paper incorporates governing equations of motion with average Reynolds equation. This model considers the surfaceroughness and profile. The corresponding computer program can be used to calculate oscillatory motion of piston during the entire trajectory, which has the excellent convergence.In addition, a set of equipment, which adopt the laser induced fluorescent method, was developed to measure the oil film thickness between the piston and the bore.

  9. Free-piston engine-and-hydraulic pump for railway vehicles

    OpenAIRE

    Golovchuk, A. F.; K. V. Prikhodko

    2013-01-01

    Purpose. The development of the free-piston diesel engine-and-hydraulic pump for the continuously variable hydrostatical transmission of mobile power vehicles. Methodology. For a long time engine builders have been interesting in the problem of developing free piston engines, which have much bigger coefficient of efficiency (40…80%). Such engines don’t have the conversion of reciprocating motion for inner combustion engine piston into rotating motion of crankshaft, from which the engine torqu...

  10. One-dimensional Brownian motion in hard rods: The adiabatic piston problem

    Science.gov (United States)

    Ebrahim Foulaadvand, M.; Shafiee, M. Mehdi

    2013-11-01

    We have investigated the motion characteristics of a movable piston immersed in a one-dimensional gas of hard rods by event-oriented molecular dynamics in the absence of thermal noise. Periodic and reflecting boundary conditions are explored. It is shown that the piston undergoes systematic oscillations with decaying amplitudes in short times before it comes to global thermodynamic equilibrium. Moreover, the diffusion of the piston is explored and analytical expressions for its equilibrium mean-squared displacement (MSD) are obtained. It is shown that the MSD of the piston does not differ much from the normal rods despite its mass and length are significantly larger.

  11. Assessment of 25 kW free-piston Stirling technology alternatives for solar applications

    Science.gov (United States)

    Erbeznik, Raymond M.; White, Maurice A.; Penswick, L. B.; Neely, Ronald E.; Ritter, Darren C.; Wallace, David A.

    The final design, construction, and testing of a 25-kW free-piston advanced Stirling conversion system (ASCS) are examined. The final design of the free-piston hydraulic ASCS consists of five subsystems: heat transport subsystem (solar receiver and pool boiler), free-piston hydraulic Stirling engine, hydraulic subsystem, cooling subsystem, and electrical and control subsystem. Advantages and disadvantages are identified for each technology alternative. Technology alternatives considered are gas bearings vs flexure bearings, stationary magnet linear alternator vs moving magnetic linear alternator, and seven different control options. Component designs are generated using available in-house procedures to meet the requirements of the free-piston Stirling convertor configurations.

  12. Modeling and Simulation of Aerial Dispersion on Piston Dispersal Mechanism%Modeling and Simulation of Aerial Dispersion on Piston Dispersal Mechanism

    Institute of Scientific and Technical Information of China (English)

    陶如意; 王浩; 黄蓓

    2011-01-01

    For the aerial dispersing interior ballistic process and submunition exterior ballistic initial conditions of cluster munition with piston maximum travel limit, a novel model is established, and the numerical simulation is performed. The piston maximum travel limit and the effect of reaction force on carrier body are researched using the internal ballistic model. Guide tube, cluster munition rotating and submunition assembly are analyzed using the submunition initial external ballistic model. The computational results are consistent with the practical process and the experimental data, and prove the rationality of this model. The theoretical methods are presented for the construction design and dispersion analysis of piston dispersal mechanism.

  13. Free-piston Stirling technology for space power

    International Nuclear Information System (INIS)

    An overview is presented of the NASA Lewis Research Center free-piston Stirling engine activities directed toward space power. This work is being carried out under NASA's new Civil Space Technology Initiative (CSTI). The overall goal of CSTI's High Capacity Power element is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA space missions. The Stirling cycle offers an attractive power conversion concept for space power needs. Discussed in this paper is the completion of the Space Power Demonstrator Engine (SPDE) testing - culminating in the generation of 25 kW of engine power from a dynamically-balanced opposed-piston Stirling engine at a temperature ratio of 2.0. Engine efficiency was approximately 22 percent. The SPDE recently has been divided into two separate single-cylinder engines, called Space Power Research Engines (SPRE), that now serve as test beds for the evaluation of key technology disciplines. These disciplines include hydrodynamic gas bearings, high-efficiency linear alternators, space qualified heat pipe heat exchangers, oscillating flow code validation, and engine loss understanding. The success of the SPDE at 650 K has resulted in a more ambitious Stirling endeavor - the design, fabrication, test and evaluation of a designed-for-space 25 kW per cylinder Stirling Space Engine (SSE). The SSE will operate at a hot metal temperature of 1050 K using superalloy materials. This design is a low temperature confirmation of the 1300 K design. It is the 1300 K free-piston Stirling power conversion system that is the ultimate goal; to be used in conjunction with the SP-100 reactor. The approach to this goal is in three temperature steps. However, this paper concentrates on the first two phases of this program - the 650 K SPDE and the 1050 K SSE

  14. Investigations of a diesel engine with devided piston rod

    Energy Technology Data Exchange (ETDEWEB)

    Blumenberg, J.; Gerster, J.

    1988-03-01

    The work in hand analyses a motor concept that was presented by the inventor to the public at the beginning of the 80s. This motor concept deals with a diesel motor with devided piston rod, which should cause a much better behaviour with regard to the specific consumption and the exhaust gas. Initiated and sponsored by the Bayerisches Oberbergamt, Munich, the authors analysed this motor concept theoretically as well as experimentally and compared the forenamed characteristic values of the base motor with the values of the modified motor. The results of the investigations did not establish the high expectations.

  15. Adaptive ride hydraulic damper with piston rod dress cap

    Energy Technology Data Exchange (ETDEWEB)

    Spisak, A.M.; Adduci, R.L.

    1987-04-28

    A hydraulic damper is described for connection between sprung and unsprung portions of a wheeled vehicle and operative to dampen the ride motions of the vehicle comprising: an outer support tube operatively connected to one of the portions. A cylinder tube is supported within the outer tubular member having a hydraulic fluid therein. A piston operatively is mounted in the cylinder tube and has means movable to varying positions to selectively vary and control the flow of fluid when stroking within the cylinder tube.

  16. Piston cylinder cell for high pressure ultrasonic pulse echo measurements.

    Science.gov (United States)

    Kepa, M W; Ridley, C J; Kamenev, K V; Huxley, A D

    2016-08-01

    Ultrasonic techniques such as pulse echo, vibrating reed, or resonant ultrasound spectroscopy are powerful probes not only for studying elasticity but also for investigating electronic and magnetic properties. Here, we report on the design of a high pressure ultrasonic pulse echo apparatus, based on a piston cylinder cell, with a simplified electronic setup that operates with a single coaxial cable and requires sample lengths of mm only. The design allows simultaneous measurements of ultrasonic velocities and attenuation coefficients up to a pressure of 1.5 GPa. We illustrate the performance of the cell by probing the phase diagram of a single crystal of the ferromagnetic superconductor UGe2. PMID:27587156

  17. Prediction for Outlet Noise of Rolling Piston Comperssor

    Directory of Open Access Journals (Sweden)

    Zhang Tieshan

    2015-01-01

    Full Text Available An acoustic wave equation with considering small perturbation is presented first by use of the fluidic mechanics and aerodynamics, then a theoretical model for predicting the outlet noise of rolling piston compressors is investigated, and the sound pressure and sound power of the outlet noise are formulated based on the acoustic wave equation. The experimental data and simulation results for the outlet noise with different rotation velocities have been compared with the discrepancy less than 2.6%, which verifies the approach presented in this paper.

  18. β Style Free-Piston Stirling Engine Control System Research

    Directory of Open Access Journals (Sweden)

    Xu Jian

    2016-01-01

    Full Text Available For the Free-Piston Stirling Engines (FPSE control system, a three -phase bridge circuit is reused as the system output about rectifier and start inverter. When FPSE system is in the power stage, the double closed loop control strategy and optimization algorithm of PI control parameters is adopted to ensure the highest system transmission efficiency under the requirements of the system output power and guarantee the stability of the running system. The simulation results prove the effectiveness of the above research content.

  19. Apodized pupil Lyot coronagraphs for arbitrary apertures. V. Hybrid Shaped Pupil designs for imaging Earth-like planets with future space observatories

    CERN Document Server

    N'Diaye, Mamadou; Pueyo, Laurent; Carlotti, Alexis; Stark, Christopher C; Perrin, Marshall D

    2016-01-01

    We introduce a new class of solutions for Apodized Pupil Lyot Coronagraphs (APLC) with segmented aperture telescopes to remove broadband diffracted light from a star with a contrast level of $10^{10}$. These new coronagraphs provide a key advance to enabling direct imaging and spectroscopy of Earth twins with future large space missions. Building on shaped pupil (SP) apodization optimizations, our approach enables two-dimensional optimizations of the system to address any aperture features such as central obstruction, support structures or segment gaps. We illustrate the technique with a design that could reach $10^{10}$ contrast level at 34\\,mas for a 12\\,m segmented telescope over a 10\\% bandpass centered at a wavelength $\\lambda_0=$500\\,nm. These designs can be optimized specifically for the presence of a resolved star, and in our example, for stellar angular size up to 1.1\\,mas. This would allow probing the vicinity of Sun-like stars located beyond 4.4\\,pc, therefore fully retiring this concern. If the fr...

  20. Knight’s Tours on Rectangular Chessboards Using External Squares

    Directory of Open Access Journals (Sweden)

    Grady Bullington

    2014-01-01

    Full Text Available The classic puzzle of finding a closed knight’s tour on a chessboard consists of moving a knight from square to square in such a way that it lands on every square once and returns to its starting point. The 8 × 8 chessboard can easily be extended to rectangular boards, and in 1991, A. Schwenk characterized all rectangular boards that have a closed knight’s tour. More recently, Demaio and Hippchen investigated the impossible boards and determined the fewest number of squares that must be removed from a rectangular board so that the remaining board has a closed knight’s tour. In this paper we define an extended closed knight’s tour for a rectangular chessboard as a closed knight’s tour that includes all squares of the board and possibly additional squares beyond the boundaries of the board and answer the following question: how many squares must be added to a rectangular chessboard so that the new board has a closed knight’s tour?

  1. Imaging sensor for monitoring of the piston mechanism in cylindrical valves

    Science.gov (United States)

    Pantiushina, Ekaterina N.; Gorbachev, Alexey A.

    2013-04-01

    Piston-cylinder assemblies are used in various actuator applications in all branches of industry, such as construction technology. It is often important for the operator to know the condition of the piston rod in the pressure-operated cylinder. A large number of operating cycles by this piston can lead to premature failure and breakage of the entire cylinder; this is conditioned by a high chance of splitting of the piston rod due to its elongation during the operating process. Therefore, it is necessary to know their operating lifetimes, for which purpose endurance tests are conducted. Since the pistons are located in hard-to-reach place, monitoring their operation via the contact method while there are in motion is not considered possible. In such situations, a non-contact method is used to monitor to moving parts, which is conducted on the basis of imaging sensors. The authors of this article have developed a new system for conducting endurance test on piston mechanism in a cylindrical valve. This system makes it possible to observe the shift of the reciprocating piston in real time, automate the process of recording data and promptly and accurately measure the parameters of the shift of the piston via a non-contact method and increase the reliability of the data received.

  2. Equation for wear of a piston-cylinder pair of a well sucker rod pump

    Energy Technology Data Exchange (ETDEWEB)

    Pisarik, M.N.

    1982-01-01

    Materials are examined on the dependence of the wear of a piston pair on the piston run. An indicator of wear of the pair, technique of calculation of wear of the pair and examples of determining the wear indicators for a number of published works are presented.

  3. Scavenge flow analysis of opposed-piston two-stroke engine based on dynamic characteristics

    Directory of Open Access Journals (Sweden)

    Fu-kang Ma

    2015-04-01

    Full Text Available Opposed-piston two-stroke engine has been proposed by Beijing Institute of Technology to improve power density and complete machine balance relative to conventional engines. In order to study opposed-piston two-stroke engine scavenging flow, a scavenging system was configured using a three-dimensional computational fluid dynamics model effectively coupled to experiments. The boundary conditions are obtained through one-dimensional working process simulation results and experiments. As the opposed-piston relative dynamic characteristics of opposed-piston two-stroke engine depend on different design and operating parameters including the opposed-piston motion phase difference and crank-connecting rod ratio, a numerical simulation program was built using MATLAB/Simulink to define opposed-piston motion profiles based on equivalent crank angle of opposed crank-connecting rod mechanism. The opposed-piston motion phase difference only affects scavenging timing while crank-connecting rod ratio affects scavenging timing and duration. Scavenging timing and duration are the main factors which affect scavenging performance. The results indicate that a match of opposed-piston motion phase difference and crank-connecting rod ratio has the potential to achieve high scavenging and trapping efficiency with a right flow in cylinder.

  4. Computer Aided Design of Kaplan Turbine Piston with\tSolidWorks

    Directory of Open Access Journals (Sweden)

    Camelia Jianu

    2010-10-01

    Full Text Available The paper presents the steps for 3D computer aided design (CAD of Kaplan turbine piston made in SolidWorks.The present paper is a tutorial for a Kaplan turbine piston 3D geometry, which is dedicaded to the Parts Sketch and Parts Features design and Drawing Geometry and Drawing Annotation.

  5. π0 Reconstruction using the Muon Piston Calorimeter Extension

    Science.gov (United States)

    Dixit, Dhruv; Phenix Collaboration

    2015-10-01

    The Muon-Piston Calorimeter Extension (MPC-EX) is a new detector in the PHENIX experiment at the Relativistic Heavy Ion Collider that was installed for the recent Run 15 of the experiment. In polarized p+p and polarized p+A collisions, an important measurement is the yield and momentum distribution of direct photons. Unaffected by the strong force, direct photons traverse the dense medium in the collision zone mostly unchanged, thereby providing information about the initial stages of the collision. However, there is a huge background of photons from other sources, primarily π0 which decay into two photons. The opening angle between the decay photons becomes smaller with higher energies of the original π0. For energies greater than ~20 GeV, the Muon Piston Calorimeter (MPC) cannot distinguish the two decay photons from a single photon, as their showers merge. The MPC-EX, an 8-layer tungsten and silicon sensor sandwich in front of the MPC, can measure and image the shower development, and help distinguish between direct photons and π0 decay photons up to higher energies than the MPC alone. We will describe the MPC-EX detector and its readout, and present the calibration procedures applied to the data in order to obtain the π0 spectrum. This project was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internships Program (SULI).

  6. Method Evaluating the Durability of Aircraft Piston Engines

    Directory of Open Access Journals (Sweden)

    Luca PIANCASTELLI

    2012-12-01

    Full Text Available A significant issue in aircraft engines is quantifying residual life to overhaul. The algorithm described in this paper calculates with a good level of reliability the residual life of a petrol piston engine. The method was tested on small, latest-generation, naturally-aspirated aircraft and racing piston engines, and has been effective in several experiments. This method is implemented directly on the electronic control system of the engine with very few lines of C-code. The method can also be used in many industrial engines. This innovative method assumes that only two main factors (power level and wear affect engine durability or time between overhauls. These two factors are considered as separate and combined with worst case criteria. The wear is assumed to follow a logarithmic law and a formula similar to the Miner’s law for material fatigue is used, making it possible to calculate the power-level curve with knowledge of only two points. The wear-curve is also related to elapsed engine cycles. The algorithm is very simple and can be implemented with just a few lines of software code accessing data collected from existing sensors. The system is currently used to evaluate actual residual life of racing engines.

  7. The low-cost and precise piston gas pressure regulator

    Science.gov (United States)

    Kudasik, Mateusz; Skoczylas, Norbert

    2016-03-01

    The present paper discusses the concept and functioning of an innovative instrument for precise stabilization of gas pressure. The piston gas pressure regulator was constructed at the Strata Mechanics Research Institute of the Polish Academy of Sciences. The tests to which the instrument was subjected involved observing the values of stabilized pressure at the level of 10 bar and 3 bar, for various gas flow rates at the outlet of the instrument. The piston gas pressure regulator operates within the range of 0-10 bar and the gas flow range of 0-240 cm3 min-1. The precision of the process of stabilizing the initial pressure is  ±0.005 bar, regardless of the gas pressure value and the flow rate observed at the outlet of the instrument. Although the pressure transducer’s accuracy is 0.25% of the full range, the conducted tests of the regulator demonstrated that the obtained changeability of the stabilized pressure is at least two times lower. Unlike some other gas pressure regulators available on the market, the instrument constructed by the authors of the present paper is highly precise when it comes to the process of stabilization, and inexpensive to build.

  8. Rectangular superpolynomials for the figure-eight knot

    CERN Document Server

    Kononov, Ya

    2016-01-01

    We rewrite the recently proposed differential expansion formula for HOMFLY polynomials of the knot $4_1$ in arbitrary rectangular representation $R=[r^s]$ as a sum over all Young sub-diagrams $\\lambda$ of $R$ with extraordinary simple coefficients $D_{\\lambda^{tr}}(r)\\cdot D_\\lambda(s)$ in front of the $Z$-factors. Somewhat miraculously, these coefficients are made from quantum dimensions of symmetric representations of the groups $SL(r)$ and $SL(s)$ and restrict summation to diagrams with no more than $s$ rows and $r$ columns. They possess a natural $\\beta$-deformation to Macdonald dimensions and produces positive Laurent polynomials, which can be considered as plausible candidates for the role of the rectangular superpolynomials. Both polynomiality and positivity are non-evident properties of arising expressions, still they are true. This extends the previous suggestions for symmetric and antisymmetric representations (when $s=1$ or $r=1$ respectively) to arbitrary rectangular representations. As usual for ...

  9. Simulation of multipactor on the rectangular grooved dielectric surface

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Libing; Wang, Jianguo, E-mail: wanguiuc@mail.xjtu.edu.cn [Key Laboratory for Physical Electronics and Devices of Ministry of Education, Xi' an Jiaotong University, Xi' an 710049 (China); Northwest Institute of Nuclear Technology, Xi' an, Shaanxi 710024 (China); Cheng, Guoxin; Zhu, Xiangqin; Xia, Hongfu [Northwest Institute of Nuclear Technology, Xi' an, Shaanxi 710024 (China)

    2015-11-15

    Multipactor discharge on the rectangular grooved dielectric surface is simulated self-consistently by using a two-and-a-half dimensional (2.5 D) electrostatic particle-in-cell (PIC) code. Compared with the electromagnetic PIC code, the former can give much more accurate solution for the space charge field caused by the multipactor electrons and the deposited surface charge. According to the rectangular groove width and height, the multipactor can be divided into four models, the spatial distributions of the multipactor electrons and the space charge fields are presented for these models. It shows that the rectangular groove in different models gives very different suppression effect on the multipactor, effective and efficient suppression on the multipactor can only be reached with a proper groove size.

  10. Microwave Magneto-Optic Bragg Modulators with Rectangular MSFVW Pulses

    Institute of Scientific and Technical Information of China (English)

    Cheng-You Luo; Bao-Jian Wu; Kun Qiu

    2009-01-01

    Microwave magneto-optic (MO) modu- lators can directly transform radio frequency (RF) signals into optical data through the Bragg diffraction of guided optical waves (GOWs) induced by microwave magneto-static waves (MSWs). According to the MO coupled-mode theory, the modulation of continuous GOWs by a rectangular magneto-static-forward- volume-wave (MSFVW) pulse in MO film waveguide is studied in the small signal case and the modulated optical pulse at the output is analyzed by means of an analytical form, which is dependent on the instantaneous diffraction intensity determined by the overlap of rectangular MSFVW pulse and light beam aperture. On the basis of it, the characteristics of MSFVW-based MO modulators can be explained well for the case of rectangular pulse modulation. It is also shown that the line codes of optical data generated by MO Bragg modulators can be controlled by adjusting the duty factor of modulating pulse signals.

  11. Critical submergence for isolated and dual rectangular intakes

    Indian Academy of Sciences (India)

    KEREM TASTAN

    2016-04-01

    This study examined critical submergence for isolated and dual rectangular intakes. It is shown that the critical submergence for an isolated intake can be predicted by disregarding whole boundary blockages on the complete imaginary critical sink surface that is the combination of imaginary complete critical cylindrical and hemi-spherical sink surfaces. It is proposed that this theory can be applied to the rectangular intakes located in general geometrical and flow conditions (i.e., intake in still water, circulation imposed flow, non-developedcross-flow, multiple intakes, etc.) and that it does not require computation of blockages caused from flow boundaries. The concept of complete sink surface (disregarding whole boundary blockages) developed for an isolated intake was also applied to dual rectangular intakes. The agreement between available test data and theoretical results was found to be satisfactory.

  12. Errors generated with the use of rectangular collimation

    Energy Technology Data Exchange (ETDEWEB)

    Parks, E.T. (Department of Allied Health, Western Kentucky University, Bowling Green (USA))

    1991-04-01

    This study was designed to determine whether various techniques for achieving rectangular collimation generate different numbers and types of errors and remakes and to determine whether operator skill level influences errors and remakes. Eighteen students exposed full-mouth series of radiographs on manikins with the use of six techniques. The students were grouped according to skill level. The radiographs were evaluated for errors and remakes resulting from errors in the following categories: cone cutting, vertical angulation, and film placement. Significant differences were found among the techniques in cone cutting errors and remakes, vertical angulation errors and remakes, and total errors and remakes. Operator skill did not appear to influence the number or types of errors or remakes generated. Rectangular collimation techniques produced more errors than did the round collimation techniques. However, only one rectangular collimation technique generated significantly more remakes than the other techniques.

  13. Connection of a piston with the rod of a hydraulic winch formine timbering

    Energy Technology Data Exchange (ETDEWEB)

    Okrut, I.I.; Filatov, V.A.; Givertz, M.L.; Pastukhanov, A.A.

    1980-09-07

    A connection of a piston with the rod of a hydraulic winch of mine timbering is suggested which includes a wire lock which is installed on the turning of the end piece and interacts with the piston. In order to improve the repair suitability and reliability, the piston is made with open bore and is installed with the possibility of axial movement on the end piece of the rod. In this case the extended length of the wire lock is smaller than the length of the circumference of the turning, the amount of the course of the piston is greater than the depth of its open bore on the diameter of the wire lock, while the width of the turning is greater than the size of the piston course.

  14. Bearing and gearing systems for rotary piston engines. Lager- und Getriebeanordnung einer Rotationskolbenmaschine

    Energy Technology Data Exchange (ETDEWEB)

    Eiermann, D.

    1991-03-14

    The proposed bearing and gearing system for rotary piston engines is provided with a trochoidal liner and triangular piston which is controlled by a synchromesh gear consisting of ring gear and pinion. The ring gear toothing is worked from the piston bore by shaping or broaching a depth of teeth which corresponds to the depth of the bore. A second, concentric bore inside the piston bore reaches from off the synchromesh gear to the ring gear and truncates the toothing of the latter. The stubs which are left hold the shell of the eccentric bearing. Cooling ducts are formed by the spaces in between. Since the bearing shell rests on the tooth stubs alone, the heat transfer from piston to eccentric bearing is considerably reduced.

  15. Demonstration of a free piston Stirling engine driven linear alternator, phase I report

    International Nuclear Information System (INIS)

    The results of the work performed under Phase I of the free piston Stirling engine demonstrator program are described. The objective of the program is to develop a 2 kW free piston Stirling engine/linear alternator energy conversion system, for an isotopic heat source, with a greater than 30% overall efficiency. Phase I was a 15-month effort to demonstrate the feasibility of the system through analysis and experimental testing of the individual components. An introduction to Stirling engines and the details of the tasks completed are presented in five major sections: (1) introduction to Stirling engine; (2) preliminary design of an advanced free piston Stirling demonstrator engine; (3) design and test of a 1 kWE output linear alternator; (4) test of a model free piston Stirling engine; and (5) development of a free piston Stirling engine computer simulation code

  16. Thermo-mechanical analysis of an SI engine piston using different boundary condition treatments

    Institute of Scientific and Technical Information of China (English)

    Amir-Hasan Kakaee; Javad Gharloghi; Aliasghar Foroughifar; Abdoreza Khanlari

    2015-01-01

    Heat transfer of an SI engine’s piston is calculated by employing three different methods based on resistor-capacitor model with the help of MATLAB code, and then the piston is thermo-mechanically analyzed using commercial ANSYS code. The results of three methods are compared to study their effects on the piston thermal behavior. It is shown that resistor−capacitor model with less number of equations and consequently less solution time, is an appropriate method for solving problems of engine piston heat transfer. In the second part, the thermal stresses due to non-uniform temperature distribution, and mechanical stresses due to mechanical loads are calculated. Finally, the temperature distributions as a thermal load along with mechanical loads are applied to the piston to determine the total stress distribution and critical fracture zones. It is found that the amount of thermal stresses is considerable.

  17. Demonstration of a free piston Stirling engine driven linear alternator, phase I report

    Energy Technology Data Exchange (ETDEWEB)

    Goldwater, B.; Piller, S.; Rauch, J.; Cella, A.

    1977-03-30

    The results of the work performed under Phase I of the free piston Stirling engine demonstrator program are described. The objective of the program is to develop a 2 kW free piston Stirling engine/linear alternator energy conversion system, for an isotopic heat source, with a greater than 30% overall efficiency. Phase I was a 15-month effort to demonstrate the feasibility of the system through analysis and experimental testing of the individual components. An introduction to Stirling engines and the details of the tasks completed are presented in five major sections: (1) introduction to Stirling engine; (2) preliminary design of an advanced free piston Stirling demonstrator engine; (3) design and test of a 1 kWE output linear alternator; (4) test of a model free piston Stirling engine; and (5) development of a free piston Stirling engine computer simulation code.

  18. Effect of relief of the actuating service of a piston on the operation of the piston pair of a well sucker rod pump

    Energy Technology Data Exchange (ETDEWEB)

    Shishov, V.V.; Lesin, A.S.

    1982-01-01

    Analysis of the existing designs of pistons indicated that decrease in the negative effect of the abrasive with simultaneous decrease in probability of jamming of the piston in the cylinder can be guaranteed by creating grooves in the form of a rhomboid grid made of smooth sections of the piston. The surface formed in this way should have a number of positive properties: withstand fatigue phenomena; promote crushing and decrease in abrasive effect of sand, present in the injected fluid; force the abrasive particles to move not rectilinearly, along the piston generatrix, but along the elongated twisting path; and to reduce the possibility of formation of plugs as a result of discontinuity in the working surface of the piston. Stand comparative tests for wear, and also field tests in the association ''Krasnodarneftegaz'' in testing well sucker rod pumps, with pistons on whose working surface there is irregular relief in the form of a rhomboid grid of grooves, confirmed the obtained conclusions.

  19. Fully-etched apodized fiber-to-chip grating coupler on the SOI platform with -0.78 dB coupling efficiency using photonic crystals and bonded Al mirror

    DEFF Research Database (Denmark)

    Ding, Yunhong; Ou, Haiyan; Peucheret, Christophe;

    2014-01-01

    We design and fabricate an ultra-high coupling efficiency fully-etched apodized grating coupler on the SOI platform using photonic crystals and bonded aluminum mirror. Ultra-high coupling efficiency of -0.78 dB with a 3 dB bandwidth of 74 nm are demonstrated....

  20. A Novel Dual-Band Circularly Polarized Rectangular Slot Antenna

    OpenAIRE

    Biao Li; Yang Ding; Ying-Zeng Yin

    2016-01-01

    A coplanar waveguide fed dual-band circularly polarized rectangular slot antenna is presented. The proposed antenna consists of a rectangular metal frame acting as a ground and an S-shaped monopole as a radiator. The spatial distribution of the surface current density is employed to demonstrate that the circular polarization is generated by the S-shaped monopole which controls the path of the surface currents. An antenna prototype, having overall dimension 37 × 37 × 1 mm3, has been fabricated...

  1. Subwavelength rectangular cavity partially filled with left-handed materials

    Institute of Scientific and Technical Information of China (English)

    Jiang Tian; Chen Yan; Feng Yi-Jun

    2006-01-01

    In this paper, we present the electromagnetic analysis of a rectangular cavity partially filled with a left-handed material slab. Our theoretical investigation shows that there exist novel resonant modes in the cavity, and such a cavity becomes a subwavelength cavity. The eigenvalue equation of the cavity is derived and the resonant frequencies of the novel modes are calculated by using numerical simulation. We also discuss the stability of the novel resonant modes and show the best condition under which a useful rectangular cavity of subwavelength dimensions with tolerable stability is obtained.

  2. Investigation of Different Piston Ring Curvatures on Lubricant Transport along Cylinder Liner in Large Two-Stroke Marine Diesel Engines

    DEFF Research Database (Denmark)

    Overgaard, Hannibal Christian; Klit, Peder; Vølund, Anders

    2016-01-01

    A theoretical investigation of the hydrodynamic lubrication of the top compression piston ring in a large two-stroke marine diesel engine is presented. The groove mounted piston ring is driven by the reciprocal motion of the piston. The ring shape follows a circular geometry and the effect of cha...

  3. Analysis of High Tc Superconducting Rectangular Microstrip Patches over Ground Planes with Rectangular Apertures in Substrates Containing Anisotropic Materials

    Directory of Open Access Journals (Sweden)

    Abderraouf Messai

    2013-01-01

    Full Text Available A rigorous full-wave analysis of high Tc superconducting rectangular microstrip patch over ground plane with rectangular aperture in the case where the patch is printed on a uniaxially anisotropic substrate material is presented. The dyadic Green’s functions of the considered structure are efficiently determined in the vector Fourier transform domain. The effect of the superconductivity of the patch is taken into account using the concept of the complex resistive boundary condition. The accuracy of the analysis is tested by comparing the computed results with measurements and previously published data for several anisotropic substrate materials. Numerical results showing variation of the resonant frequency and the quality factor of the superconducting antenna with regard to operating temperature are given. Finally, the effects of uniaxial anisotropy in the substrate on the resonant frequencies of different TM modes of the superconducting microstrip antenna with rectangular aperture in the ground plane are presented.

  4. Free-piston engine-and-hydraulic pump for railway vehicles

    Directory of Open Access Journals (Sweden)

    A. F. Golovchuk

    2013-04-01

    Full Text Available Purpose. The development of the free-piston diesel engine-and-hydraulic pump for the continuously variable hydrostatical transmission of mobile power vehicles. Methodology. For a long time engine builders have been interesting in the problem of developing free piston engines, which have much bigger coefficient of efficiency (40…80%. Such engines don’t have the conversion of reciprocating motion for inner combustion engine piston into rotating motion of crankshaft, from which the engine torque is transferred to the power machine transmission. Free-piston engines of inner combustion don’t have the crank mechanism (CM that significantly reduces mechanical losses for friction. Such engines can be used as compressors. Free-piston engine compressor (FPEC – is a free-piston machine in which energy received from engine’s cylinder is being transferred direct to compressor’s pistons connected with operational pistons of engine without crank mechanism. Part of the pressed air is being consumed for engine cylinder drain and the other part is going to the consumer. Findings. The use of free-piston engines-and-hydraulic pumps as power-transmission plants of power vehicles (diesel locomotives, combine harvester, tractors, cars and other mobile and stationary power installations with the continuously variable transmissions allows cost effectiveness improvement and metal consumption reduction of these vehicles, since the cost effectiveness of FPE is higher by 25-30%, and the metal consumption is lower by 40-50%. Originality. One of the important advantages of the free-piston engines is their simplicity and engine balance. As a result of the crank mechanism absence their construction is much simplified and the vibrations, peculiar to the ordinary engines are eliminated. In such installation the engine pistons are directly connected through the rod to compressor pistons and therefore there are no losses in the bearing bushes. Practical value. The free-piston

  5. Internal flow characteristics of a rectangular ramjet air intake

    NARCIS (Netherlands)

    Moerel, J.-L.; Veraar, R.G.; Halswijk, W.H.C.; Pimentel, R.; Corriveau, D.; Hamel, N.; Lesage, F.; Vos, J.B.

    2009-01-01

    Two research institutes TNO Defence, Security and Safety and DRDC-Valcartier have worked together on the improvement of modeling and simulation tools for the functioning of supersonic air intakes for realistic ramjet engines of tactical missiles. The emphasis laid on complex rectangular intake desig

  6. Calculations of circular waveguide with a rectangular metal insert.

    Directory of Open Access Journals (Sweden)

    Yu. K. Sydoruk

    2010-05-01

    Full Text Available Calculated and analyzed the basic parameters of electromagnetic wave in a circular waveguide with a rectangular metal plate in the following cases: when  the circular waveguide without metal plate for a H11 wave of subcritical, critical and supercritical. For calculations was used a finite element method and Ansoft HFSS program.

  7. Numerical prediction of wave impact loads on multiple rectangular beams

    DEFF Research Database (Denmark)

    Mayer, Stefan; Nielsen, Kristian Bendix; Hansen, E.A.

    2005-01-01

    Wave impact on one and two structural beams with rectangular cross section is simulated with a two-dimensional finite volume method, solving the unsteady Euler equations and employing a VOF-type method for the description of the free surface. Four different test series are carried out, each...

  8. Relationship between room shape and acoustics of rectangular concert halls

    DEFF Research Database (Denmark)

    Klosak, Andrzej K.; Gade, Anders Christian

    2008-01-01

    Extensive acoustics computer simulations have been made using Odeon computer simulation software. In 24 rectangular rooms representing "shoe-box" type concert halls with volumes of 8 000 m3, 12 000 m3 and 16 000 m3 from 300 to 850 measurements positions have been analysed. Only room averaged...

  9. Numerical simulation of small section rectangular tube in parallel welding

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The welding temperature field and deformation of parallel arrangement small-section rectangular tubes is calculated by using a non-contact model. After comparing the computed results with the experimentally measured results, it shows that there exist big errors when applying this model to the numerical simulation of small-section rectangular tube's welding temperature field and deformation. Based on a simple analysis of the errors, a contact model is presented. The heat transfer and stress analysis between small-section rectangular tubes and clamping fixture are simulated by using direct constraints method, and then the laws of the temperature distribution, which coincide with experiment, are obtained. A further numerical analysis of the stress and deformation are made, it shows that a "T" shaped stress-field is formed in the vicinity of the weld. As the stress-field departs from the centroid of tubes', this leads to the small rectangular tubes not only have a longitudinal deflection, but also have a transverse bending and deformation.

  10. Two-Dimensional Rectangular Stock Cutting Problem and Solution Methods

    Institute of Scientific and Technical Information of China (English)

    Zhao Hui; Yu Liang; Ning Tao; Xi Ping

    2001-01-01

    Optimal layout of rectangular stock cutting is still in great demand from industry for diversified applications. This paper introduces four basic solution methods to the problem: linear programming, dynamic programming, tree search and heuristic approach. A prototype of application software is developed to verify the pros and cons of various approaches.

  11. The demagnetizing field of a non-uniform rectangular prism

    DEFF Research Database (Denmark)

    Smith, Anders; Nielsen, Kaspar Kirstein; Christensen, Dennis;

    2010-01-01

    The effect of demagnetization on the magnetic properties of a rectangular ferromagnetic prism under non-uniform conditions is investigated. A numerical model for solving the spatially varying internal magnetic field is developed, validated and applied to relevant cases. The demagnetizing field......-uniformity of the internal field, especially for non-constant temperature distributions and composite magnetic materials....

  12. Integrated two-cylinder liquid piston Stirling engine

    Science.gov (United States)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd

    2014-10-01

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.

  13. CFD Modeling of Free-Piston Stirling Engines

    Science.gov (United States)

    Ibrahim, Mounir B.; Zhang, Zhi-Guo; Tew, Roy C., Jr.; Gedeon, David; Simon, Terrence W.

    2001-01-01

    NASA Glenn Research Center (GRC) is funding Cleveland State University (CSU) to develop a reliable Computational Fluid Dynamics (CFD) code that can predict engine performance with the goal of significant improvements in accuracy when compared to one-dimensional (1-D) design code predictions. The funding also includes conducting code validation experiments at both the University of Minnesota (UMN) and CSU. In this paper a brief description of the work-in-progress is provided in the two areas (CFD and Experiments). Also, previous test results are compared with computational data obtained using (1) a 2-D CFD code obtained from Dr. Georg Scheuerer and further developed at CSU and (2) a multidimensional commercial code CFD-ACE+. The test data and computational results are for (1) a gas spring and (2) a single piston/cylinder with attached annular heat exchanger. The comparisons among the codes are discussed. The paper also discusses plans for conducting code validation experiments at CSU and UMN.

  14. Integrated two-cylinder liquid piston Stirling engine

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd, E-mail: todd.sulchek@me.gatech.edu [George W. Woodruff School of Mechanical Engineering and Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2014-10-06

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.

  15. Integrated two-cylinder liquid piston Stirling engine

    International Nuclear Information System (INIS)

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.

  16. Heat transfer analysis of liquid piston compressor for hydrogen applications

    DEFF Research Database (Denmark)

    Kermani, Nasrin Arjomand; Rokni, Masoud

    2015-01-01

    A hydrogen compression technology using liquid as the compression piston is investigated from heat transfer point of view. A thermodynamic model, simulating a single compression stroke, is developed to investigate the heat transfer phenomena inside the compression chamber. The model is developed...... and through the walls, is investigated and compared with the adiabatic case. The results show that depending on heat transfer correlation, the hydrogen temperature reduces slightly between 0.2% and 0.4% compared to the adiabatic case, at 500bar, due to the large wall resistance and small contact area...... at the interface. Moreover, the results of the sensitivity analysis illustrates that increasing the total heat transfer coefficients at the interface and the wall, together with compression time, play key roles in reducing the hydrogen temperature. Increasing the total heat transfer coefficient at the interface...

  17. Investigation of Valve Plate in Water Hydraulic Axial Piston Motor

    Institute of Scientific and Technical Information of China (English)

    聂松林; 李壮云; 等

    2002-01-01

    This paper has introduced the developments of water hydraulic axial piston equipments.According to the effects of physicochemical properties of water on water hydraulic components,a novel valve plate for water hydraulic axial motor has been put forward,whose moment exerted by the fluid field between valve plate and bearing plate is balanced entirely.The material screening experiment of valve plate is done on the test rig.Through numerical simulation the effects of some geometry parameters on the performance of water hydraulic motor have been studied.The silencing grooves on the valve plate in water hydraulic motor can reduce the pressure shock and the occurrence of cavitation effectively.It is evident that the appropriate structure should change the wear status between matching paris and reduces the wear and specific pressure of the matching pairs.The specimen with the new type valve plate is used in a tool system.

  18. Apodizer aperture for lasers

    Science.gov (United States)

    Jorna, Siebe; Siebert, Larry D.; Brueckner, Keith A.

    1976-11-09

    An aperture attenuator for use with high power lasers which includes glass windows shaped and assembled to form an annulus chamber which is filled with a dye solution. The annulus chamber is shaped such that the section in alignment with the axis of the incident beam follows a curve which is represented by the equation y = (r - r.sub.o).sup.n.

  19. 5-kWe Free-piston Stirling Engine Convertor

    Science.gov (United States)

    Chapman, Peter A.; Vitale, Nicholas A.; Walter, Thomas J.

    2008-01-01

    The high reliability, long life, and efficient operation of Free-Piston Stirling Engines (FPSEs) make them an attractive power system to meet future space power requirements with less mass, better efficiency, and less total heat exchanger area than other power convertor options. FPSEs are also flexible in configuration as they can be coupled with many potential heat sources and various heat input systems, heat rejection systems, and power management and distribution systems. Development of a 5-kWe Stirling Convertor Assembly (SCA) is underway to demonstrate the viability of an FPSE for space power. The design is a scaled-down version of the successful 12.5-kWe Component Test Power Converter (CTPC) developed under NAS3-25463. The ultimate efficiency target is 25% overall convertor efficiency (electrical power out over heat in). For the single cylinder prototype now in development, cost and time constraints required use of economical and readily available materials (steel versus beryllium) and components (a commercially available linear alternator) and thus lower efficiency. The working gas is helium at 150 bar mean pressure. The design consists of a displacer suspended on internally pumped gas bearings and a power piston/alternator supported on flexures. Non-contacting clearance seals are used between internal volumes. Heat to and from the prototype convertor is done via pumped liquid loops passing through shell and tube heat exchangers. The preliminary and detail designs of the convertor, controller, and support systems (heating loop, cooling loop, and helium supply system) are complete and all hardware is on order. Assembly and test of the prototype at Foster- Miller is planned for early 2008, when work will focus on characterizing convertor dynamics and steady-state operation to determine maximum power output and system efficiency. The device will then be delivered to Auburn University where assessments will include start-up and shutdown characterization and

  20. CFD analysis of a diaphragm free-piston Stirling cryocooler

    Science.gov (United States)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-10-01

    This paper presents a Computational Fluid Dynamics (CFD) analysis of a novel free-piston Stirling cryocooler that uses a pair of metal diaphragms to seal and suspend the displacer. The diaphragms allow the displacer to move without rubbing or moving seals. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicated the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. The diaphragm's large diameter and short stroke produces a significant radial component to the oscillating flow fields inside the cryocooler which were not modelled in the one-dimensional analysis tool Sage that was used to design the prototypes. Compared with standard pistons, the diaphragm geometry increases the gas-to-wall heat transfer due to the higher velocities and smaller hydraulic diameters. A Computational Fluid Dynamics (CFD) model of the cryocooler was constructed to understand the underlying fluid-dynamics and heat transfer mechanisms with the aim of further improving performance. The CFD modelling of the heat transfer in the radial flow fields created by the diaphragms shows the possibility of utilizing the flat geometry for heat transfer, reducing the need for, and the size of, expensive heat exchangers. This paper presents details of a CFD analysis used to model the flow and gas-to-wall heat transfer inside the second prototype cryocooler, including experimental validation of the CFD to produce a robust analysis.

  1. Development of a model capable of predicting the performance of piston ring-cylinder liner-like tribological interfaces

    DEFF Research Database (Denmark)

    Felter, C.L.; Vølund, A.; Imran, Tajammal;

    2010-01-01

    Friction in the piston ring package (piston, piston rings, and liner) is a major source of power consumption in large two-stroke marine diesel engines. In order to improve the frictional and wear performance, knowledge about the tribological interface between piston rings and liner is needed. The...... at a high speed. This article represents the first steps in the pursuit of being able to accurately model the interface between a piston ring and the cylinder liner in large two-stroke diesel engines....

  2. Internal combustion engine with a central crankshaft and integral tandem annular pistons

    Science.gov (United States)

    Esparbes, Bernard

    1993-08-01

    An internal combustion engine with tandem annular pistons and a central crankshaft is disclosed, based on that found in British patent 11027 of 11 May 1914. The piston block formed by the two pistons presents, at each axial extremity, a double axial skirt fitted with an outer crown forming the head of the piston as such, and an inner crown forming an inlet pump with a holding chamber radially located at the inside of the corresponding annular cylinder, in which the piston head delimits a combustion chamber. Radial fingers, crossing axial openings of the crankcase and radial holes of the piston block, have their inner radial ends engaged within wavy sinusoidal peripheral slots arranged in a bulging central portion of the central crankshaft set into rotation by alternating axial movements of the piston block. The admission of fuel or combustion sustaining gas is ensured axially by the extremities, valves, and openings in the end plates closing the holding chambers in which the inner crowns slide, fitted with valves to act as an inlet pump. The invention is particularly applicable to aircraft engines in view of the ease in which the shaft rotation can be adapted to such a use.

  3. On the identification of piston slap events in internal combustion engines using tribodynamic analysis

    Science.gov (United States)

    Dolatabadi, N.; Theodossiades, S.; Rothberg, S. J.

    2015-06-01

    Piston slap is a major source of vibration and noise in internal combustion engines. Therefore, better understanding of the conditions favouring piston slap can be beneficial for the reduction of engine Noise, Vibration and Harshness (NVH). Past research has attempted to determine the exact position of piston slap events during the engine cycle and correlate them to the engine block vibration response. Validated numerical/analytical models of the piston assembly can be very useful towards this aim, since extracting the relevant information from experimental measurements can be a tedious and complicated process. In the present work, a coupled simulation of piston dynamics and engine tribology (tribodynamics) has been performed using quasi-static and transient numerical codes. Thus, the inertia and reaction forces developed in the piston are calculated. The occurrence of piston slap events in the engine cycle is monitored by introducing six alternative concepts: (i) the quasi-static lateral force, (ii) the transient lateral force, (iii) the minimum film thickness occurrence, (iv) the maximum energy transfer, (v) the lubricant squeeze velocity and (vi) the piston-impact angular duration. The validation of the proposed methods is achieved using experimental measurements taken from a single cylinder petrol engine in laboratory conditions. The surface acceleration of the engine block is measured at the thrust- and anti-thrust side locations. The correlation between the theoretically predicted events and the measured acceleration signals has been satisfactory in determining piston slap incidents, using the aforementioned concepts. The results also exhibit good repeatability throughout the set of measurements obtained in terms of the number of events occurring and their locations during the engine cycle.

  4. Effect of shell drilling stiffness on response calculations of rectangular plates and tubes of rectangular cross-section under compression.

    Energy Technology Data Exchange (ETDEWEB)

    Gorman, Jhana; Hales, Jason Dean; Corona, Edmundo

    2010-05-01

    This report considers the calculation of the quasi-static nonlinear response of rectangular flat plates and tubes of rectangular cross-section subjected to compressive loads using quadrilateralshell finite element models. The principal objective is to assess the effect that the shell drilling stiffness parameter has on the calculated results. The calculated collapse load of elastic-plastic tubes of rectangular cross-section is of particular interest here. The drilling stiffness factor specifies the amount of artificial stiffness that is given to the shell element drilling Degree of freedom (rotation normal to the plane of the element). The element formulation has no stiffness for this degree of freedom, and this can lead to numerical difficulties. The results indicate that in the problems considered it is necessary to add a small amount of drilling tiffness to obtain converged results when using both implicit quasi-statics or explicit dynamics methods. The report concludes with a parametric study of the imperfection sensitivity of the calculated responses of the elastic-plastic tubes with rectangular cross-section.

  5. Theoretical study of flow ripple for an aviation axial-piston pump with damping holes in the valve plate

    Institute of Scientific and Technical Information of China (English)

    Guan Changbin; Jiao Zongxia; He Shouzhan

    2014-01-01

    Based on the structure of a certain type of aviation axial-piston pump’s valve plate which adopts a pre-pressurization fluid path (consisting a damping hole, a buffer chamber, and an orifice) to reduce flow ripple, a single-piston model of the aviation axial-piston pump is presented. This sin-gle-piston model comprehensively considers fluid compressibility, orifice restriction effect, fluid resistance in the capillary tube, and the leakage flow. Besides, the instantaneous discharge areas used in the single-piston model have been calculated in detail. Based on the single-piston model, a multi-piston pump model has been established according to the simple hydraulic circuit. The sin-gle-and multi-piston pump models have been realized by the S-function in Matlab/Simulink. The developed multi-piston pump model has been validated by being compared with the numerical result by computational fluid dynamic (CFD). The effects of the pre-pressurization fluid path on the flow ripple and the instantaneous pressure in the piston chamber have been studied and opti-mized design recommendations for the aviation axial-piston pump have been given out.

  6. A CPW-Fed Rectangular Ring Monopole Antenna for WLAN Applications

    OpenAIRE

    Sangjin Jo; Hyunjin Choi; Beomsoo Shin; Sangyeol Oh; Jaehoon Lee

    2014-01-01

    We present a simple coplanar waveguide- (CPW-) fed rectangular ring monopole antenna designed for dual-band wireless local area network (WLAN) applications. The antenna is based on a simple structure composed of a CPW feed line and a rectangular ring. Dual-band WLAN operation can be achieved by controlling the distance between the rectangular ring and the ground plane of the CPW feed line, as well as the horizontal vertical lengths of the rectangular ring. Simulated and measured data show tha...

  7. Directionality of sperm whale sonar clicks and its relation to piston radiation theory

    DEFF Research Database (Denmark)

    Beedholm, K.; Møhl, Bertel

    2006-01-01

    This paper investigates the applicability to sperm whales of the theory of sound radiating from a piston. The theory is applied to a physical model and to a series of sperm whale clicks. Results show that wave forms of off-axis signals can be reproduced by convolving an on-axis signal...... with the spatial impulse response of a piston. The angle of a recorded click can be estimated as the angle producing the spatial impulse response that gives the best match with the observation when convolved with the on-axis wave form. It is concluded that piston theory applies to sperm whale sonar click emission....

  8. Research on Measurements for Temperature and Stress of Pistons in Internal Combustion Engine

    Institute of Scientific and Technical Information of China (English)

    DONG Xiao-rui; TAN Jian-song

    2008-01-01

    In both numerical simulation and experimental research for the piston of internal combustion engine, the verification foundations are always insufficient. The reason is the measurements for its transient temperature and stress under actual operation conditions are very difficult. A multi-channel measurement-storage technology is used in the engine bench experiment to measure the piston temperature and stress in real time. The temperature and stress changes in the engine operation process are obtained. They provide reliable instructive criteria for numerical analysis and experiment of the piston working state.

  9. Acoustic radiation field of the truncated parametric source generated by a piston radiator model and experiment

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiaoliang; ZHU Zhemin; DU Gonghuan; TANG Haiqing; LI Shui; MIAO Rongxing

    2001-01-01

    A theoretical model is presented to describe the parametric acoustic field generated by a piston radiator. In the model, the high-frequency primary wave interaction region that is truncated by a low-pass acoustic filter can be viewed as a cylindrical source within the Rayleigh distance of the piston. When the radius of the piston is much smaller than the length of the parametric region, this model is reduced to the Berketey's End-Fire Line Array model. Comparison between numerical calculations and experimental measurement show that the generated parametric sound field (especially near the axis) agrees well with the experiment results.

  10. 数字式气体活塞压力计的活塞系统设计%Piston-Cylinder Assembly Design of the Digital Piston Pressure Gauge

    Institute of Scientific and Technical Information of China (English)

    王丽; 盛晓岩

    2012-01-01

    The piston-cylinder assembly design method of digital piston pressure gauge is introduced. The design principle, material selection and design of critical dimension are introduced in detail. The result is certified by the performance index of the piston-cylinder assembly and digital piston pressure gauge. Theoretical basis is provided for the rapid development of digital piston pressure gauge.%介绍了数字式气体活塞压力计的关键部件——活塞系统的设计方法,详细阐述了活塞系统的设计原则、材料的选择以及关键尺寸的设计,并通过了活塞系统性能指标和数字式活塞压力计性能指标的验证,为数字式活塞压力计技术的迅速发展提供了理论依据.

  11. A Space Cam Mechanism for Power Transmission of an Opposite-cylinder Piston Engine

    Directory of Open Access Journals (Sweden)

    Zhang Haoyue

    2015-01-01

    Full Text Available For the purpose of improving the engine’s power density, we put forward a new type of power transmission mechanism which is used for opposed-cylinder engine. The gas pressure acts on the cam through the piston and push rod, and the spindle rotation of external is driven by the cam. The design of spatial cam work surface is completed by using the enveloping theory of a family of space curves, the force between roller and cam is analyzed using dynamic analysis software. Under the condition of equal number, size and stroke of piston, the new one with larger power density is more compact in structure than the traditional power transmission mechanism, and the reaction force on either side of the main shaft and the acting force between pistons and cylinders are smaller than those in traditional one, which prolongs the service life of the pistons.

  12. Studies on the optimisation of contactless piston rod glands; Untersuchung zur Optimierung beruehrungsloser Kolbenstangendichtungen

    Energy Technology Data Exchange (ETDEWEB)

    Heinrichs, K. [WTZ fuer Motoren- und Maschinenforschung Rosslau GmbH (Germany); Nickol, J. [Neuman und Esser GmbH und Co. KG, Maschinenfabrik, Uebach-Palenberg (Germany)

    1996-12-01

    The article describes the function of labyrinth seals as contactless piston rod glands of different design. Piston rod glands of reciprocating compressors are discussed. Also described are novel, patented piston rod glands which are a combination of labyrinth seals and contact seals. This combination serves to optimize the packing length. Further, a program for calculating pressure and temperature curves in piston rod glands is described which can be applied to any given labyrinth. (AKF) [Deutsch] Der Beitrag beschreibt die Funktionsweise der Labyrinthdichtungen als beruehrungslose Kolbenstangendichtungen in verschiedenen Ausfuehrungen. Es werden Kolbenstangendichtungen von Hubkolbenkompressoren betrachtet. Berichtet wird auch von neuartigen, patentierten Kolbenstangendichtungen als Kombination von Laby- und Kontaktdichtelementen. Diese Kombination optimiert die Packungslaenge. Darueber hinaus wird auf einem Programm zur Ermittlung von Druck- und Temperaturverlaeufen in Kolbenstangendichtungen hingewiesen, das auf jedes beliebige Labyrinth angewendet werden kann. (AKF)

  13. Investigations of high-frequency induction hardening process for piston rod of shock absorber

    Institute of Scientific and Technical Information of China (English)

    Xianhua Cheng; Qianqian Shangguan

    2005-01-01

    The microhardness of piston rods treated with different induction hardening processes was tested. The experimental results reveal that the depth of the hardened zone is proportional to the ratio of the moving speed of the piston rod to the output power of the induction generator. This result is proved correct through the Finite Element Method (FEM) simulation of the thermal field of induction heating. From tensile and impact tests, an optimized high frequency induction hardening process for piston rods has been obtained, where the output power was 82%×80 kW and the moving speed of workpiece was 5364 mm/min. The piston rods, treated by the optimized high frequency induction hardening process, show the best comprehensive mechanical performance.

  14. Novel Tribotester for Cylinder Liner/Piston Ring Contacts of Two Stroke Marine Diesel Engines

    DEFF Research Database (Denmark)

    Pedersen, Michael Torben; Imran, Tajammal; Klit, Peder;

    2009-01-01

    A good tribological description for the cylinder liner and piston ring materials is always desired in order to achieve an improved combination of the materials. The piston ring package in a two-stroke-diesel engine operates in three lubrication regimes and the materials must be characterized...... in relation to this before a final selection is made. A tribo-test-apparatus is developed to study the tribological performance and to rank the different combinations of cylinder liner and piston ring materials of two stroke marine diesel engines. The test apparatus is based on the block-on-ring principle...... and is capable of studying the process of friction, oil film formation between cylinder liner, and piston ring surfaces and the corresponding wear. Two test procedures are developed to verify the reproducibility of the measurements obtained with this test apparatus. These reproducibility test procedures were...

  15. Lubrication of Piston Rings in Large 2–and 4–stroke Diesel Engines

    DEFF Research Database (Denmark)

    Felter, Christian Lotz

    Piston rings are vital components of any internal combustion engine, and their performance affect important properties such as frictional losses, oil consumption, and wear of parts. This thesis deals with the lubrication of piston rings from a theoretical point of view. Predictions are made using...... is fulfilled in a quasi-static sense a concrete example is analyzed using the Reynolds equation. Next a free surface 2D code based on the compressible Navier–Stokes equations is developed. The main idea is to model also the oil film outside the piston ring. Through time integration the movement of the inlet...... point on the piston ring can be calculated. While the model based on the Reynolds equation has a shortcoming with respect to the assumption of steady-state conditions, the model based on the Navier–Stokes equations turns out to be computationally expensive. Different remedies such as implicit time...

  16. Design and theoretical analysis of a sliding valve distribution radial piston pump

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Guo; Shengdun, Zhao; Yanghuiwen, Yu [Xian Jiaotong University, Xian (China); Peng, Shang [Xian Engineering University of Armed Police Force, Xian (China)

    2016-01-15

    A Sliding valve distribution radial piston pump (SVDRPP) is presented. In this pump, a new distribution method that uses sliding valves to distribute oil for the piston chambers is developed. With this design, the disadvantages brought by the distribution shaft and the check valves (traditional distribution mechanisms), such as the poor stress state of the shaft and the energy waste for opening the check valves, are expected to be eliminated. In addition, a method of using pressure oil to accomplish the returning stroke of the piston is also proposed, which could be used to replace the usage of springs along with their shortcomings. A pump with five pistons is designed as an example to elaborate the structure and the working principle of SVDRPP. Furthermore, the flow characteristics of SVDRPP are studied, and the formulas of the displacement, the average flow rate and the instantaneous flow rate are deduced.

  17. Adaptive individual-cylinder thermal state control using piston cooling for a GDCI engine

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Gregory T; Husted, Harry L; Sellnau, Mark C

    2015-04-07

    A system for a multi-cylinder compression ignition engine includes a plurality of nozzles, at least one nozzle per cylinder, with each nozzle configured to spray oil onto the bottom side of a piston of the engine to cool that piston. Independent control of the oil spray from the nozzles is provided on a cylinder-by-cylinder basis. A combustion parameter is determined for combustion in each cylinder of the engine, and control of the oil spray onto the piston in that cylinder is based on the value of the combustion parameter for combustion in that cylinder. A method for influencing combustion in a multi-cylinder engine, including determining a combustion parameter for combustion taking place in in a cylinder of the engine and controlling an oil spray targeted onto the bottom of a piston disposed in that cylinder is also presented.

  18. High Specific Power Multiple-Cylinder Alpha Free-Piston Stirling Engine Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort will result in a design of a 30 kWe dual opposed alpha free-piston Stirling engine power conversion system for space applications, and provide...

  19. Free vibration analysis of rectangular plates with central cutout

    Directory of Open Access Journals (Sweden)

    Kanak Kalita

    2016-12-01

    Full Text Available A nine-node isoparametric plate element in conjunction with first-order shear deformation theory is used for free vibration analysis of rectangular plates with central cutouts. Both thick and thin plate problems are solved for various aspect ratios and boundary conditions. In this article, primary focus is given to the effect of rotary inertia on natural frequencies of perforated rectangular plates. It is found that rotary inertia has significant effect on thick plates, while for thin plates the rotary inertia term can be ignored. It is seen that the numerical convergence is very rapid and based on comparison with experimental and analytical data from literature, it is proposed that the present formulation is capable of yielding highly accurate results. Finally, some new numerical solutions are provided here, which may serve as benchmark for future research on similar problems.

  20. Differential expansion and rectangular HOMFLY for the figure eight knot

    CERN Document Server

    Morozov, A

    2016-01-01

    Differential expansion (DE) for a Wilson loop average in representation $R$ is built to respect degenerations of representations for small groups. At the same time it behaves nicely under some changes of the loop, e.g. of some knots in the case of $3d$ Chern-Simons theory. Especially simple is the relation between the DE for the trefoil $3_1$ and for the figure eight knot $4_1$. Since arbitrary colored HOMFLY for the trefoil are known from the Rosso-Jones formula, it is therefore enough to find their DE in order to make a conjecture for the figure eight. We fulfil this program for all rectangular representation $R=[r^s]$, i.e. make a plausible conjecture for the rectangularly colored HOMFLY of the figure eight knot, which generalizes the old result for totally symmetric and antisymmetric representations.

  1. A Novel Dual-Band Circularly Polarized Rectangular Slot Antenna

    Directory of Open Access Journals (Sweden)

    Biao Li

    2016-01-01

    Full Text Available A coplanar waveguide fed dual-band circularly polarized rectangular slot antenna is presented. The proposed antenna consists of a rectangular metal frame acting as a ground and an S-shaped monopole as a radiator. The spatial distribution of the surface current density is employed to demonstrate that the circular polarization is generated by the S-shaped monopole which controls the path of the surface currents. An antenna prototype, having overall dimension 37 × 37 × 1 mm3, has been fabricated on FR4 substrate with dielectric constant 4.4. The proposed antenna achieves 10 dB return loss bandwidths and 3 dB axial ratio (AR in the frequency bands 2.39–2.81 GHz and 5.42–5.92 GHz, respectively. Both these characteristics are suitable for WLAN and WiMAX applications.

  2. Are Haar-like Rectangular Features for Biometric Recognition Reducible?

    DEFF Research Database (Denmark)

    Nasrollahi, Kamal; Moeslund, Thomas B.

    2013-01-01

    Biometric recognition is still a very difficult task in real-world scenarios wherein unforeseen changes in degradations factors like noise, occlusion, blurriness and illumination can drastically affect the extracted features from the biometric signals. Very recently Haar-like rectangular features...... which have usually been used for object detection were introduced for biometric recognition resulting in systems that are robust against most of the mentioned degradations [9]. The problem with these features is that one can define many different such features for a given biometric signal...... and it is not clear whether all of these features are required for the actual recognition or not. This is exactly what we are dealing with in this paper: How can an initial set of Haar-like rectangular features, that have been used for biometric recognition, be reduced to a set of most influential features...

  3. Analytical theory of an unloaded rectangular microstrip patch

    Science.gov (United States)

    Chang, D. C.

    1981-01-01

    A graphical method for determining the size of a resonant rectangular microstrip patch for a specified frequency is given. Using an expression obtained from the reflection coefficient of a transverse electromagnetic (TEM) wave in a semi-infinite microstrip patch, the resonance condition of a given mode for a patch of finite size is derived in a manner analogous to that of a rectangular, waveguide cavity. Radiation is shown to be in the form of both surface waves and space waves and is dependent on the angles of incidence for waves impinging onto the edges of the patch. By varying the aspect ratio, it is also possible to modify the Q factor of a resonant path. Analytical expressions for the resonant frequency and the Q factor are then derived under the assumption of a very thin substrate slab, encountered frequently in the application. Design curves in the form of the 'Argand diagram' are then presented for microstrip patches with fixed aspect ratios.

  4. Characterizing octagonal and rectangular fibers for MAROON-X

    CERN Document Server

    Sutherland, Adam P; Miller, Katrina R; Seifahrt, Andreas; Bean, Jacob L

    2016-01-01

    We report on the scrambling performance and focal-ratio-degradation (FRD) of various octagonal and rectangular fibers considered for MAROON-X. Our measurements demonstrate the detrimental effect of thin claddings on the FRD of octagonal and rectangular fibers and that stress induced at the connectors can further increase the FRD. We find that fibers with a thick, round cladding show low FRD. We further demonstrate that the scrambling behavior of non-circular fibers is often complex and introduce a new metric to fully capture non-linear scrambling performance, leading to much lower scrambling gain values than are typically reported in the literature (<1000 compared to 10,000 or more). We find that scrambling gain measurements for small-core, non-circular fibers are often speckle dominated if the fiber is not agitated.

  5. Flexural rigidity of biaxially loaded reinforced concrete rectangular column sections

    Science.gov (United States)

    Resheidat, M.; Ghanma, M.; Sutton, C.; Chen, Wai-Fah

    1995-05-01

    An exact analysis is carried out utilizing the parabola-rectangle stress-strain curve for concrete and a typical idealized stress-strain curve for steel to develop the moment-curvature relationship for biaxially loaded reinforced concrete rectangular column sections. Based on that, the flexural rigidity EI of the section is determined at the yield curvature. A computer program is written by FORTRAN 77 to handle the required computations. The influence of material properties, the effect of steel ratios, and the impact of axial loads on the EI estimation were investigated. This study leads to the development of a new equation to estimate the flexural rigidity EI of reinforced concrete biaxially loaded rectangular columns in which these factors were considered. It is shown that the new equation stems from the actual behavior of the column. Therefore, it is recommended for general use in the design of slender columns.

  6. Performance of NBPE in Rectangular Microstrip Patch Antenna

    Directory of Open Access Journals (Sweden)

    Tushar

    2014-02-01

    Full Text Available In this paper we use a rectangular microstrip patch antenna with fed patch contains four notches of equal Length and width (L×W and having one parasitic patch, to achieve dual band operation of proposed microstrip patch antenna, is analyzed using circuit theory concept. The theoretical and simulated results of proposed antenna are compared. The return loss of NBPE using rectangular microstrip patch antenna decreased and bandwidth at dual operating frequency 1.44 GHz & 1.80 GHz are increased at a substrate height of 1.6 mm. This paper shows the decreased in return loss & improves in Gain as well as bandwidth using NBPE. These structures are simulated using IE3D version 12.29 Zeland software incorporation.

  7. End depth in steeply sloping rough rectangular channels

    Indian Academy of Sciences (India)

    Subhasish Dey

    2000-02-01

    The paper presents a theoretical model to compute the end depth of a free overfall in steeply sloping rough rectangular channels. A momentum equation based on the Boussinesq approximation is applied to obtain the equation of the end depth. The effect ofstreamline curvature at the free surface is utilized to develop the differential equation for the flow profile upstream of the free overfall of a wide rectangular channel. As direct solutions for the end depth and flow profile cannot be obtained owing to implicit forms of the developed equations, an auto-recursive search scheme is evolved to solve these equations simultaneously. A method for estimation of discharge from the known end depth and Nikuradse equivalent sand roughness is also presented. Results from the present model correspond satisfactorily with experimental observations except for some higher roughnesses.

  8. Differential expansion and rectangular HOMFLY for the figure eight knot

    Science.gov (United States)

    Morozov, A.

    2016-10-01

    Differential expansion (DE) for a Wilson loop average in representation R is built to respect degenerations of representations for small groups. At the same time it behaves nicely under some changes of the loop, e.g. of some knots in the case of 3d Chern-Simons theory. Especially simple is the relation between the DE for the trefoil 31 and for the figure eight knot 41. Since arbitrary colored HOMFLY for the trefoil are known from the Rosso-Jones formula, it is therefore enough to find their DE in order to make a conjecture for the figure eight. We fulfill this program for all rectangular representation R = [rs ], i.e. make a plausible conjecture for the rectangularly colored HOMFLY of the figure eight knot, which generalizes the old result for totally symmetric and antisymmetric representations.

  9. A Multi-Objective Approach to Visualize Proportions and Similarities Between Individuals by Rectangular Maps

    DEFF Research Database (Denmark)

    Carrizosa, Emilio; Guerrero, Vanesa; Morales, Dolores Romero

    In this paper we address the problem of visualizing the proportions and the similarities attached to a set of individuals. We represent this information using a rectangular map, i.e., a subdivision of a rectangle into rectangular portions so that each portion is associated with one individual...... adjacencies that the rectangular map adds, and the last one is to minimize the total deviation of the areas of the portions in the rectangular map from the given proportions. To guide the location of the rectangles, we have designed a tailored MultiDimensional Scaling for building rectangular maps. We study...

  10. Wavefront control simulations for the Giant Magellan Telescope: Field-dependent segment piston control

    OpenAIRE

    Quiros-Pacheco, Fernando; Conan, Rod; McLeod, Brian; Irarrazaval, Ben; Bouchez, Antonin

    2015-01-01

    We present in this paper preliminary simulation results aimed at validating the GMT piston control strategy. Wewill in particular consider an observing mode in which an Adaptive Optics (AO) system is providing fast on-axisWF correction with the Adaptive Secondary Mirror (ASM), while the phasing system using multiple SegmentPiston Sensors (SPS) makes sure that the seven GMT segments remain phased. Simulations have been performedwith the Dynamic Optical Simulation (DOS) tool developed at the GM...

  11. Pengaruh Desain Sistem Pegas pada Olah Gerak Piston dari Motor Bakar Gerak Linier Bersilinder Tunggal

    OpenAIRE

    Setiono Prabowo; Aguk Zuhdi Muhammad Fathallah

    2013-01-01

    Permasalahan pada linear engine adalah siklus kerja baliknya. Banyak cara untuk mengganti posisi piston dari chrankshaft pada conventional engine, saalah satunya menggunakan system pegas. Keunikan penggunaan pegas sebagai siklus kerja balik untuk linear engine ssatu silinder adalah defleksi dari pegas. Namun untuk daya yang kecil piston tidak dapat terdefleksi sempurna sampai titik mati bawah. Karena itu dibutuhkan kajian pada linear engine dengan menggunakan pegas sebagai siklus kerja balikn...

  12. Thermomechanical Fatigue Life Prediction for a Marine Diesel Engine Piston considering Ring Dynamics

    OpenAIRE

    Tao He; Xiqun Lu; Dequan Zou; Yibin Guo; Wanyou Li; Minli Huang

    2014-01-01

    A newly designed marine diesel engine piston was modeled using a precise finite element analysis (FEA). The high cycle fatigue (HCF) safety factor prediction procedure designed in this study incorporated lubrication, thermal, and structure analysis. The piston ring dynamics calculation determined the predicted thickness of lubrication oil film. The film thickness influenced the calculated magnitude of the heat transfer coefficient (HTC) used in the thermal loads analysis. Moreover, the gas pr...

  13. The development and testing of ceramic components in piston engines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    McEntire, B.J. [Norton Co., Northboro, MA (United States). Advanced Ceramics Div.; Willis, R.W.; Southam, R.E. [TRW, Inc., Cleveland, OH (United States)

    1994-10-01

    Within the past 10--15 years, ceramic hardware has been fabricated and tested in a number of piston engine applications including valves, piston pins, roller followers, tappet shims, and other wear components. It has been shown that, with proper design and installation, ceramics improve performance, fuel economy, and wear and corrosion resistance. These results have been obtained using rig and road tests on both stock and race engines. Selected summaries of these tests are presented in this review paper.

  14. Optimization of Axial Piston Units Based on Demand-driven Relief of Tribological Contacts

    OpenAIRE

    Haug, Stefan; Geimer, Marcus

    2016-01-01

    Markets show a clear trend towards an ever more extensive electronic networking in mobile and stationary applications. This requires a certain degree of electronic integration of hydraulic components such as axial piston pumps. Beside some wellknow approaches, the transmission of axial piston units still is relatively unexplored regarding electronification. Nonetheless there is a quite high potential to be optimized by electronic. In view of this fact, the present paper deals with the tribolo...

  15. FINITE DIFFERENCE MODEL OF A CIRCULAR FIN WITH RECTANGULAR PROFILE

    OpenAIRE

    GİRGİN, İbrahim; EZGİ, Cüneyt

    2015-01-01

    Numerical methods are commonly used in engineering where the analytical resultsare not reached or as a support of experimental studies. Various techniques are being usedas a numeritical method as finite difference, finite volume or finite elements, etc. In thisstudy, numerical solutions are obtained for a circular fin of rectangular profile using finitedifference method, and the results are compared to the analytical solutions. It is seen thatthe analytical solution and numerical results are ...

  16. Initial magnetic field distribution around high rectangular bus bars

    OpenAIRE

    Cividjian Grigore A.

    2014-01-01

    The one-dimensional transient electromagnetic field in and around a system of two nonmagnetic homogenous rectangular high thin bars can be analytically evaluated if the ratio of average initial magnetic field on the two sides of thin bar, or of the ratio of initial magnetic fields in middle of the bar height is known. In this paper, using appropriate conformal mappings, an exact analytical solution for these ratios are proposed in the case of very thin bars...

  17. Bandwidth Study of the Microwave Reflectors with Rectangular Corrugations

    Science.gov (United States)

    Zhang, Liang; He, Wenlong; Donaldson, Craig R.; Cross, Adrian W.

    2016-09-01

    The mode-selective microwave reflector with periodic rectangular corrugations in the inner surface of a circular metallic waveguide is studied in this paper. The relations between the bandwidth and reflection coefficient for different numbers of corrugation sections were studied through a global optimization method. Two types of reflectors were investigated. One does not consider the phase response and the other does. Both types of broadband reflectors operating at W-band were machined and measured to verify the numerical simulations.

  18. Classification of flow patterns in rectangular shallow reservoirs

    OpenAIRE

    DUFRESNE, Matthieu; Dewals, Benjamin; Erpicum, Sébastien; Archambeau, Pierre; Pirotton, Michel

    2010-01-01

    This work focuses on the experimental classification of flow patterns in rectangular shallow reservoirs, including symmetric flows without any reattachment point to asymmetric flows with one reattachment point, two reattachment points, or two reattachment points and one detachment point. The median position and the natural variability of the reattachment lengths of asymmetric flows were measured for forty geometric and hydraulic conditions. The effects of dimensionless flow depth, Froude numb...

  19. Qualitative Model of the Input Impedance of Rectangular Microstrip Antenna

    Directory of Open Access Journals (Sweden)

    Saeed Reza Ostadzadeh

    Full Text Available In this paper, a fuzzy-based approach is proposed so as to predict the input impedance of the rectangular microstrip antenna. In the proposed approach, at first, behavior of single microstrip antenna is represented as simple and unchanged membership functions, and the feed probe effect on the input impedance is then extracted as simple curves so that the input impedance of microstrip antenna in despite of other existing models is efficiently predicted.

  20. Anisotropic rectangular nonconforming finite element analysis for Sobolev equations

    Institute of Scientific and Technical Information of China (English)

    SHI Dong-yang; WANG Hai-hong; GUO Cheng

    2008-01-01

    An anisotropic rectangular nonconforming finite element method for solving the Sobolev equations is discussed under semi-discrete and full discrete schemes.The corresponding optimal convergence error estimates and superclose property are derived,which are the same as the traditional conforming finite elements.Furthermore,the global superconvergence is obtained using a post-processing technique.The numerical results show the validity of the theoretical analysis.

  1. Lightweight design of the rectangular mirror using topology optimization

    Science.gov (United States)

    Xiang, Meng; Li, Fu

    2014-09-01

    That minimizing the mass of space optical remote sensor at the same time guaranteeing of structural rigidity and surface shape accuracy, became a new critical research topic. This paper achieves detailed design of meniscus rectangular lens body structure by taking the choice of materials, design of supporting structure and lightweight form of mirror into account. And we established lightweight concrete of the mirror under self-weight by the method of topological optimization design. For the optimization, we used a 3-D model of the rectangular mirror and calculated based on that making minimum weight of the mirror as an objective function constrained by the displacement of the mirror surface. Finally finite element analysis method was adopted to get the optimization results analyzed and compared with the traditional triangular lightweight model. Analysis results prove that: the new mirror is superior to the traditional model in surface accuracy and structural rigidity, PV value, RMS value and the lightweight rate. With enough high dynamic-static stiffness and thermal stability, this kind of mirror can meet the demand under the self-weight and the random vibration environment respectively. So this article puts forward a new idea in the lightweight design of rectangular mirror.

  2. Pengaruh Desain Sistem Pegas pada Olah Gerak Piston dari Motor Bakar Gerak Linier Bersilinder Tunggal

    Directory of Open Access Journals (Sweden)

    Setiono Prabowo

    2013-03-01

    Full Text Available Permasalahan pada linear engine adalah siklus kerja baliknya. Banyak cara untuk mengganti posisi piston dari chrankshaft pada conventional engine, saalah satunya menggunakan system pegas. Keunikan penggunaan pegas sebagai siklus kerja balik untuk linear engine ssatu silinder adalah defleksi dari pegas. Namun untuk daya yang kecil piston tidak dapat terdefleksi sempurna sampai titik mati bawah. Karena itu dibutuhkan kajian pada linear engine dengan menggunakan pegas sebagai siklus kerja baliknya,Terutama ketika piston tidak dapat terdefleksi sampai titik mati bawah. Solidwork cosmos motion dapat digunakan untuk menganalisa kajian ini. Model dari engine termasuk conventional dan linear engine sudah ada desain, perakitan dan disimulasikan pada piston dynamic. Beberapa data meliputi daya dan dimensi pegas sudah dilakukan sebelum simulasi. Pegas yang asli akan digantikan dengan pegas yang fleksibel dimana tersedia data base dari cosmos motion. Gesekan meliputi dalam kajian akan disimulasikan dengan dua body contact pada kondisi terlumasi. Hasilnya menunjukan olah gerak piston dari conventional engine dan linear engine seperti displacement, velocity dan acceleration sudah jelas berbeda. Pengaruh dari gesekan juga ada pada pada kajian ini. Namun, olah gerak piston pada linear engine berputar pada sumbu z.

  3. NOISE IDENTIFICATION FOR HYDRAULIC AXIAL PISTON PUMP BASED ON ARTIFICIAL NEURAL NETWORKS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The noise identification model of the neural networks is established for the 63SCY14-1B hydraulic axial piston pump. Taking four kinds of different port plates as instances, the noise identification is successfully carried out for hydraulic axial piston pump based on experiments with the MATLAB and the toolbox of neural networks. The operating pressure, the flow rate of hydraulic axial piston pump, the temperature of hydraulic oil, and bulk modulus of hydraulic oil are the main parameters having influences on the noise of hydraulic axial piston pump. These four parameters are used as inputs of neural networks, and experimental data of the noise are used as outputs of neural networks. Error of noise identification is less than 1% after the neural networks have been trained. The results show that the noise identification of hydraulic axial piston pump is feasible and reliable by using artificial neural networks. The method of noise identification with neural networks is also creative one of noise theoretical research for hydraulic axial piston pump.

  4. LED Monitoring System of the Phenix Muon Piston Calorimeter

    Science.gov (United States)

    Motschwiller, Steven

    2010-11-01

    The Muon Piston Calorimeter in the PHENIX experiment at RHIC has a monitoring system consisting of LEDs and PIN diodes to calibrate out the time dependent changes to the detector. The LEDs track the temperature and radiation-damage changes to the response of the MPC, while the absolute calibration can be done using 0̂ decays. To execute this, LEDs flash light through the PbWO4 crystal to the Avalanche Photo Diodes The MPC is made up of 416 independent electromagnetic calorimeter towers. By using the LEDs we can correct for changes in the gains of each tower in the MPC, on a run by run basis. Because the LED value only gives a relative measurement of the gain over time, this method of calibration can only be used in conjunction with absolute calibrations provided by 0̂ decays or by minimum ionizing peaks . This work will be used to make a final measurement on Transverse energy at √sNN = 200 GV in Au+Au collisions.

  5. The Influence of Cylinder Lubrication on Piston Slap

    Science.gov (United States)

    Gerges, S. N. Y.; de Luca, J. C.; Lalor, N.

    2002-10-01

    A model has been developed for determining the time history of piston slap impact force. This model takes into account the influence of the oil film on the impact behaviour, which was found to be an important factor. However, it was also found that entrapped gas bubbles in the oil are equally significant. Three test rigs were designed and built to study these effects on the impact phenomenon and extensive tests were carried out. The impact force time history has been determined using Reynolds' theory. Results have shown that Reynolds' theory for fluid film squeezing can be applied for oil film damping determination. However, the experimental results have also shown that when gas is entrapped during the impact, this theory considerably overpredicts the magnitude of the impact. An eight-degree-of-freedom lumped parameter model was developed through the dynamic analysis of each component of an internal combustion engine's reciprocating system. The effective damping factor derived from this model was found to be inversely proportional to the oil film thickness cubed, as expected from Reynolds' theory. A dynamic model has been proposed, where the oil film mixed with bubbles is considered to be analogous to a serial spring and damping system. By incorporating a spring in series with this damper, the effect of the bubbles can also be predicted.

  6. Finite-temperature Casimir pistons for an electromagnetic field with mixed boundary conditions and its classical limit

    Energy Technology Data Exchange (ETDEWEB)

    Teo, L P [Faculty of Information Technology, Multimedia University, Jalan Multimedia, Cyberjaya, 63100, Selangor Darul Ehsan (Malaysia)], E-mail: lpteo@mmu.edu.my

    2009-03-13

    In this paper, the finite-temperature Casimir force acting on a two-dimensional Casimir piston due to an electromagnetic field is computed. It was found that if mixed boundary conditions are assumed on the piston and its opposite wall, then the Casimir force always tends to restore the piston toward the equilibrium position, regardless of the boundary conditions assumed on the walls transverse to the piston. In contrast, if pure boundary conditions are assumed on the piston and the opposite wall, then the Casimir force always tends to pull the piston toward the closer wall and away from the equilibrium position. The nature of the force is not affected by temperature. However, in the high-temperature regime, the magnitude of the Casimir force grows linearly with respect to temperature. This shows that the Casimir effect has a classical limit as has been observed in other literature.

  7. Experience with piston and piston-rod seals for high-pressure reciprocating compressors injecting natural gas on North Sea production platforms

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, R.S.

    1983-12-01

    The need to restrict flaring of associated natural gas has emphasized the importance of reliability of high-pressure reinjection compressors installed on certain North Sea platforms. This paper reviews the contribution made by the development of piston and rod seals used on injection compressors, with reference to three important fields: Beryl, Statfjord, and Thistle.

  8. Stable Operation and Electricity Generating Characteristics of a Single-Cylinder Free Piston Engine Linear Generator: Simulation and Experiments

    OpenAIRE

    Huihua Feng; Yu Song; Zhengxing Zuo; Jiao Shang; Yaodong Wang; Anthony Paul Roskilly

    2015-01-01

    We present a novel design of a single-cylinder free piston engine linear generator (FPELG) incorporating a linear motor as a rebound device. A systematic simulation model of this FPELG system was built containing a kinematic and dynamic model of the piston and mover, a magneto-electric model of the linear generator, a thermodynamic model of the single-cylinder engine, and a friction model between the piston ring and cylinder liner. Simulations were performed to understand the relationships be...

  9. Analysis and Proof‐of‐Concept Experiment of Liquid‐Piston Compression for Ocean Compressed Air Energy Storage (OCAES) System

    OpenAIRE

    Park, Joong-kyoo; Ro, Paul I.; He, Xiao; Mazzoleni, Andre P.

    2014-01-01

    An analysis and a proof‐of‐concept experiment of liquid‐piston compression were conducted for a table‐top Ocean Compressed Air Energy Storage (OCAES) prototype. A singlecylinder‐ type piston surrounded by water was modeled and analyzed based on convection heat transfer with fully developed internal flow, the assumption adopted by earlier liquid piston study in literature. Transient numerical results of this model were calculated for a polytropic compression with different polytropic index val...

  10. Experimental and numerical investigations of oil film formation and friction in a piston ring-liner contact

    OpenAIRE

    Avan, E.Y.; Spencer, A.; Dwyer-Joyce, R.S.; Almqvist, A.; Larsson, R.

    2013-01-01

    The piston ring–cylinder liner contact is a major source of the total parasitic losses in an internal combustion engine. The lubrication process of this contact highly influences the amount of friction, oil consumption and wear that occurs. In this work, a reciprocating test rig combined with an ultrasonic film thickness measurement system was developed and then used for tribological investigation of the piston ring–cylinder liner contact under idealised cold conditions. A special piston ring...

  11. An Experimental Investigation on the Combustion and Heat Release Characteristics of an Opposed-Piston Folded-Cranktrain Diesel Engine

    OpenAIRE

    Fukang Ma; Changlu Zhao; Fujun Zhang; Zhenfeng Zhao; Zhenyu Zhang; Zhaoyi Xie; Hao Wang

    2015-01-01

    In opposed-piston folded-cranktrain diesel engines, the relative movement rules of opposed-pistons, combustion chamber components and injector position are different from those of conventional diesel engines. The combustion and heat release characteristics of an opposed-piston folded-cranktrain diesel engine under different operating conditions were investigated. Four phases: ignition delay, premixed combustion, diffusion combustion and after combustion are used to describe the heat release p...

  12. Space Power Free-Piston Stirling Engine Scaling Study

    Science.gov (United States)

    Jones, D.

    1989-01-01

    The design feasibility study is documented of a single cylinder, free piston Stirling engine/linear alternator (FPSE/LA) power module generating 150 kW-electric (kW sub e), and the determination of the module's maximum feasible power level. The power module configuration was specified to be a single cylinder (single piston, single displacer) FPSE/LA, with tuning capacitors if required. The design requirements were as follows: (1) Maximum electrical power output; (2) Power module thermal efficiency equal to or greater than 20 percent at a specific mass of 5 to 8 kg/kW(sub e); (3) Heater wall temperature/cooler wall temperature = 1050 K/525 K; (4) Sodium heat-pipe heat transport system, pumped loop NaK (sodium-potassium eutectic mixture) rejection system; (5) Maximum power module vibration amplitude = 0.0038 cm; and (6) Design life = 7 years (60,000 hr). The results show that a single cylinder FPSE/LA is capable of meeting program goals and has attractive scaling attributes over the power range from 25 to 150 kW(sub e). Scaling beyond the 150 kW(sub e) power level, the power module efficiency falls and the power module specific mass reaches 10 kg/kW(sub e) at a power output of 500 kW(sub e). A discussion of scaling rules for the engine, alternator, and heat transport systems is presented, along with a detailed description of the conceptual design of a 150 kW(sub e) power module that meets the requirements. Included is a discussion of the design of a dynamic balance system. A parametric study of power module performance conducted over the power output range of 25 to 150 kW(sub e) for temperature ratios of 1.7, 2.0, 2.5, and 3.0 is presented and discussed. The results show that as the temperature ratio decreases, the efficiency falls and specific mass increases. At a temperature ratio of 1.7, the 150 kW(sub e) power module cannot satisfy both efficiency and specific mass goals. As the power level increases from 25 to 150 kW(sub e) at a fixed temperature ratio, power

  13. Pump rod forces due to hydrodynamic effects in piston pumps

    Energy Technology Data Exchange (ETDEWEB)

    Verheij, F.

    1986-10-01

    A mathematical model has been set up to describe flow and pressure fluctuations in a pump system of a wind pump for single acting piston pumps. With this, hydrodynamic forces acting on the pump rod can be calculated. Hydrodynamic forces make an important contribution to the total pump rod force. Experiments have been performed on a laboratory version of the so-called Tanzania pump. Different air volumes of the delivery airchamber, different delivery heads and different rotational speeds were chosen to obtain enough information to check the validity of the model. For the measuring and the elaboration of the measurements, computer programs were developed using a new data acquisition system. This new system operates very satisfactorily. A new magneto-inductive flow meter has been installed. However there are still incertainties as to the reliability of this sensor. Simple analytical expressions using Fourier transform analysis methods were obtained for the pressure and flow fluctuations in the pump system, from which the forces acting on the pump rod can be calculated. Comparison between theoretical and experimental results suggest that the pressure fluctuations are predicted correctly by theory. This is yet not the case in comparing theory and experiment with regards to the flow fluctuations. Apart from the irreliability of the flow meter, this could also be due to the complex flow in and out of the airchamber that is not correctly modelled in theory. There is certainly need for further analysis of the measurements possibly supplemented by a new set of measurements. However, design rules already can be derived from the results obtained so far. A good sizing of the airchamber in relation to the stroke volume of the pump keeps the pressure fluctuations, and so the fluctuating hydrodynamic forces acting on the pump rod, within bounds. 13 refs.

  14. Development of rolling mill for rectangular orthodontic wires production

    Directory of Open Access Journals (Sweden)

    G.E. Totten

    2007-09-01

    Full Text Available Purpose: In orthodontic treatments, wires of different metallic alloys are used for alignment, leveling, correction of the molar position, space closing, finish and retention. The purpose of the paper is the characteristics of austenitic stainless steel wires, with a square traverse section, which were produced using a rolling mill built for this purpose, are presented hereDesign/methodology/approach: With respect to finish and retention, these wires are responsible for adequate positioning of the upper teeth on the lower teeth. Wires that are subjected to incisor torque require high resistance and stiffness. For this, wires of rectangular austenitic stainless steel are used due to high modulus of elasticity and good corrosion resistance in the oral environment. Because of the rectangular geometry, wire production requires process development suitable for industrial scale manufacture with geometric characteristics and mechanical properties better adapted to the use conditions.Findings: To obtain wires with such characteristics, a rolling mill was developed for the production of rectangular wires by a rolling process with the objective of reducing cost of the cold drawing process that is currently used which utilize complex and expensive wire-drawing dies. In addition to the rolling process itself, wire deformation, microhardness, tension and bend tests were also performed.Research limitations/implications: A rolling-mill was built that successfully produced dental wires within acceptable tolerances and physical/mechanical properties.These wires exhibited excellent hardness and tensile strength, although slightly less than analogous commercial wires. It is expected that this problem are corrected by using initial wires with a higher hardness, since this property is directly related with the tensile strength.Originality/value: In these tests, wire geometry, surface finish and mechanical properties were successfully adapted for use in orthodontic

  15. Resonant Response of Rectangular AFM Cantilever in Liquid

    Institute of Scientific and Technical Information of China (English)

    CHEN Yu-Hang; HUANG Wen-Hao

    2007-01-01

    Dynamic characteristics of atomic force microscopy (AFM) cantilevers can be influenced by their working media.We perform an experimental study on the resonant responses of rectangular AFM cantilevers with different sizes immersed in various viscous fluids. The measured resonance frequencies in liquids are used to validate several theoretical models. Comparison shows the analytical model proposed by Sader [J. Appl. Phys. 84 (1998) 64] can give the best agreement with the experimental results with the maximum relative error nearly 16% for all the cantilevers in different liquids. The ratio between the resonant frequencies in air and water is almost independent of the cantilever length, which is consistent with the theoretical analyses.

  16. Experimental study of subsonic microjet escaping from a rectangular nozzle

    Science.gov (United States)

    Aniskin, V. M.; Maslov, A. A.; Mukhin, K. A.

    2016-10-01

    The first experiments on the subsonic laminar microjets escaping from the nozzles of rectangular shape are carried out. The nozzle size is 83.3x3823 microns. Reynolds number calculated by the nozzle height and the average flow velocity at the nozzle exit ranged from 58 to 154. The working gas was air at room temperature. The velocity decay and velocity fluctuations along the center line of the jet are determined. The fundamental difference between the laminar microjets characteristics and subsonic turbulent jets of macro size is shown. Based on measurements of velocity fluctuations it is shown the presence of laminar-turbulent transition in microjets and its location is determined.

  17. A Novel Rectangular Element for Piezoelectric Laminated Plates

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yong; WANG Xing-wei; SUN Ya-fei

    2004-01-01

    Based on the classical laminated plate theory, a novel finite element formulation is presented for modeling the static response of laminated composites containing distributed piezoelectric ceramic subjected to electric loadings. A four-node rectangular composite element with an additional voltage freedom per piezoelectric layer is implemented for the analysis. The element can predict more accurately the bending response of the structure because of its new displacement radixes. Numerical examples ere performed and the calculated data compare very well with existing results in the literatures.

  18. Investigation of streamer corona discharge induced by rectangular impulse voltage

    International Nuclear Information System (INIS)

    The development of a pulsed streamer corona discharge was investigated experimentally. Positive polarity voltage was used together with nearly rectangular pulse shapes which facilitate the definition of discharge characteristics. The measurements were performed both with wire-cylinder and point-plane electrode systems. Oscillograms of current and voltage pulses were used to determine corona characteristics such as the linear current density, the volume energy density and its variations during the pulse, and the resistance of the discharge cell. The obtained experimental data complement the information on pulsed corona discharges published up to now. (J.U.)

  19. Algorithms for Generating Convex Polyhedrons Over Three Dimensional Rectangular Grid

    Directory of Open Access Journals (Sweden)

    G. Ramesh Chandra

    2012-05-01

    Full Text Available This paper discusses various algorithms related to generation of 3-D convex polyhedrons. These convexpolyhedrons can be used as structuring elements in the mathematical morphological processing of 3-Ddigital images. The first algorithm proposes a new way of automatic construction of 256 convexpolyhedrons in a 3-D rectangular grid by removing the duplicate subsets. The second algorithm proposes away for hierarchy construction in visualizing the relationships between sets and their correspondingsubsets of all 256 convex polyhedrons. The third algorithm proposes a way of visualizing all 256 convexpolyhedrons depending on user selection.

  20. Initial magnetic field distribution around high rectangular bus bars

    Directory of Open Access Journals (Sweden)

    Cividjian Grigore A.

    2014-01-01

    Full Text Available The one-dimensional transient electromagnetic field in and around a system of two nonmagnetic homogenous rectangular high thin bars can be analytically evaluated if the ratio of average initial magnetic field on the two sides of thin bar, or of the ratio of initial magnetic fields in middle of the bar height is known. In this paper, using appropriate conformal mappings, an exact analytical solution for these ratios are proposed in the case of very thin bars. Obtained values are compared with FEM results for relatively thick bars.

  1. Extending the MODPATH algorithm to rectangular unstructured grids

    Science.gov (United States)

    Pollock, David W.

    2016-01-01

    The recent release of MODFLOW-USG, which allows model grids to have irregular, unstructured connections, requires a modification of the particle-tracking algorithm used by MODPATH. This paper describes a modification of the semi-analytical particle-tracking algorithm used by MODPATH that allows it to be extended to rectangular-based unstructured grids by dividing grid cells with multi-cell face connections into sub-cells. The new method will be incorporated in the next version of MODPATH which is currently under development.

  2. The kernel of the adjacency matrix of a rectangular mesh

    OpenAIRE

    Tomei, Carlos; Vieira, Tania

    2002-01-01

    Given an m x n rectangular mesh, its adjacency matrix A, having only integer entries, may be interpreted as a map between vector spaces over an arbitrary field K. We describe the kernel of A: it is a direct sum of two natural subspaces whose dimensions are equal to $\\lceil c/2 \\rceil$ and $\\lfloor c/2 \\rfloor$, where c = gcd (m+1,n+1) - 1. We show that there are bases to both vector spaces, with entries equal to 0, 1 and -1. When K = Z/(2), the kernel elements of these subspaces are described...

  3. Nonlinear dynamics and control of a vibrating rectangular plate

    Science.gov (United States)

    Shebalin, J. V.

    1983-01-01

    The von Karman equations of nonlinear elasticity are solved for the case of a vibrating rectangular plate by meams of a Fourier spectral transform method. The amplification of a particular Fourier mode by nonlinear transfer of energy is demonstrated for this conservative system. The multi-mode system is reduced to a minimal (two mode) system, retaining the qualitative features of the multi-mode system. The effect of a modal control law on the dynamics of this minimal nonlinear elastic system is examined.

  4. Rectangular C-Shaped Slot Microstrip Antenna for Linear Polarization

    Directory of Open Access Journals (Sweden)

    Girraj Sharma

    2012-03-01

    Full Text Available The design of a rectangle microstrip antenna with Linear polarization (LP is presented. To compact the antenna size and overcome the high impedance problem, the LP antenna is excited by a co-axial cable. Several prototypes of the squarering LP antennas with various substrate thicknesses (0.75mm_ultralam2000 and 1.56mm_rt_duroid3003 have been constructed and studied experimentally. The simple rectangular and compact C shaped microstrip antenna is simulated with IE3D and MATLAB and their corresponding result is compared.

  5. Experimental Study of Near Wake Flow Behind a Rectangular Cylinder

    OpenAIRE

    Abdollah Shadaram; Mahdi A. Fard; Noorallah Rostamy

    2008-01-01

    The turbulence characteristics of the near wake flow behind a rectangular cylinder is investigated in a two-dimensional analysis using a hot-wire anemometer. The time-averaged and fluctuating components of the velocity are measured for a cylinder having various width-to-height (b h-1) ratios. The measurements are carried out in a low-speed wind tunnel. Data from hot-wire anemometer is collected by a data acquisition system. The results show that the turbulence intensity in the flow wake decre...

  6. 3-D LDA study of a rectangular jet

    Science.gov (United States)

    Morrison, Gerald L.; Tatterson, Gary B.; Swan, David H.

    1988-01-01

    The flow field of a rectangular jet with a 2:1 aspect ratio was studied at an axial Reynolds number of 100,000 (Mach number 0.09) using three-dimensional laser Doppler velocimetry. The flow field survey resulted in mean velocity vector field plots and contour plots of the Reynolds stress tensor components. This paper presents contour plots in the planes of the jet minor and major axes at different axial locations. These data contribute substantially to currently available data of jet flow fields and will provide a valuable database for three-dimensional modeling.

  7. Damage Analysis of Rectangular Section Composite Beam under Pure Bending

    Science.gov (United States)

    Liu, Yiping; Xiao, Fan; Liu, Zejia; Tang, Liqun; Fang, Daining

    2013-02-01

    Laminated composite beams are commonly used in engineering applications involving macro to nano structures. Based on the assumption that plain sections remain plain after deformation, this paper analyzes stress distributions in cross-ply laminated composite beams with rectangular cross-sections, and formulates the basic damage equations through Kachanov's damage definition and Janson's failure criterion. The location of the neutral axis and the ultimate bending moment are obtained for pure bending cases. The effect of the elastic modulus of the two layers on the damage evolution is analyzed; a reasonable damage composite beam model is proposed to predict the ultimate bending moment.

  8. Optimal paths of piston motion of irreversible diesel cycle for minimum entropy generation

    Directory of Open Access Journals (Sweden)

    Ge Yanlin

    2011-01-01

    Full Text Available A Diesel cycle heat engine with internal and external irreversibility’s of heat transfer and friction, in which the finite rate of combustion is considered and the heat transfer between the working fluid and the environment obeys Newton’s heat transfer law [q≈ Δ(T], is studied in this paper. Optimal piston motion trajectories for minimizing entropy generation per cycle are derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston motion trajectories for the cases of with piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum deceleration boundary segments, respectively. Numerical examples for optimal configurations are provided, and the results obtained are compared with those obtained when maximizing the work output with Newton’s heat transfer law. The results also show that optimizing the piston motion trajectories could reduce engine entropy generation by more than 20%. This is primarily due to the decrease in entropy generation caused by heat transfer loss on the initial portion of the power stroke.

  9. Simulation of a Martini Displacer Free Piston Stirling Engine for Electric Power Generation

    Directory of Open Access Journals (Sweden)

    Pascal Stouffs

    2000-03-01

    Full Text Available We consider a gamma type free piston engine with the MARTINI configuration for electric power generation. A dynamic simulation of this engine has been developed using a decoupled analysis. The equation of motion of the free piston induces a strong coupling between the electrical load and the thermodynamics inside the free piston Stirling engine. From the thermodynamics point of view, the piston-displacer phase lag is an important parameter. We point out that, if the electrical circuit elements (R-L-C are constants, the phase lag between the free pistons and displacer motions is far from the optimum for the engine considered. For both cases of stand-alone engine with an independent electrical load, or grid-connected engine, it is shown how, by varying the instantaneous value of the electrical resistance, one can in a very simple way multiply the net electrical power by a factor 4 to 6, and the efficiency by a factor 1.25 to 2, without any engine geometry modification.

  10. Compact high-efficiency linear cryocooler in single-piston moving magnet design for HOT detectors

    Science.gov (United States)

    Rühlich, I.; Mai, M.; Rosenhagen, C.; Withopf, A.; Zehner, S.

    2012-06-01

    State of the art Mid Wave IR-technology has the potential to rise the FPA temperature from 77K to 130-150K (High Operation Temperature, HOT). Using a HOT FPA will significantly lower SWaP and keep those parameters finally dominated by the employed cryocooler. Therefore, compact high performance cryocoolers are mandatory. AIM has developed the SX040 cooler, optimized for FPA temperatures of about 95K (presented at SPIE 2010). The SX040 cooler incorporates a high efficient dual piston driving mechanism resulting in a very compact compressor of less than 100mm length. Higher compactness - especially shorter compressors - can be achieved by change from dual to single piston design. The new SX030 compressor has such a single piston Moving Magnet driving mechanism resulting in a compressor length of about 60mm. Common for SX040 and SX030 family is a Moving Magnet driving mechanism with coils placed outside the helium vessel. In combination with high performance plastics for the piston surfaces this design enables lifetimes in excess of 20,000h MTTF. Because of the higher FPA temperature and a higher operating frequency also a new displacer needs to be developed. Based on the existing 1/4" coldfinger interface AIM developed a new displacer optimized for an FPA temperature of 140K and above. This paper gives an overview on the development of this new compact single piston cryocooler. Technical details and performance data will be shown.

  11. The optimal path of piston motion for Otto cycle with linear phenomenological heat transfer law

    Institute of Scientific and Technical Information of China (English)

    XIA ShaoJun; CHEN LinGen; SUN FengRui

    2009-01-01

    An Otto cycle engine with internal and external irreversibilities of friction and heat leakage, in which the heat transfer between the working fluid and the environment obeys linear phenomenological heat transfer law [q∝△(T-1)], is studied in this paper. The optimal piston motion trajectory for maximizing the work output per cycle is derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston trajectories for the cases of with and without piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum deceleration boundary segments,respectively. Numerical examples for optimal configuration are provided, and the obtained results are compared with those obtained with Newton's heat transfer law [q∝△(T)]. The results also show that optimizing the piston motion can improve power and efficiency of the engine by more than 9%. This is primarily due to the decrease in heat leakage loss on the initial portion of the power stroke.

  12. Modeling and Simulation on Axial Piston Pump Based on Virtual Prototype Technology

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bin; XU Bing; XIA Chunlin; YANG Huayong

    2009-01-01

    A particular emphasis is placed on the virtual prototype technology (VPT) of axial piston pump. With this technology it is convenient and flexible to build a complicated 3D virtual based on real physical model. The actual kinematics pairs of the parts were added on the model. The fluid characters were calculated by hydraulic software. The shape of the parts, the flexible body of parts, etc were improved in this prototype. So the virtual prototype of piston pump can work in computer like a real piston pump, and the flow ripple, pressure pulsation, motion principle, stress of parts, etc can be investigated. The development of the VPT is introduced at the beginning, and the modeling process of the virtual prototype is explained. Then a special emphasis is laid on the relationship between the dynamics model and the hydraulic model, and the simulations on the flow ripple, pressure pulsation, motion principle, the stress and strain distribution of the middle shaft and piston are operated. Finally, the advantages and disadvantages of the VPT are discussed. The improved virtual prototype of piston pump more tally with the real situation and the VPT has a great potential in simulation on hydraulic components.

  13. The optimal path of piston motion for Otto cycle with linear phenomenological heat transfer law

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    An Otto cycle engine with internal and external irreversibilities of friction and heat leakage, in which the heat transfer between the working fluid and the environment obeys linear phenomenological heat transfer law [q ∝△(T -1)], is studied in this paper. The optimal piston motion trajectory for maximizing the work output per cycle is derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston trajectories for the cases of with and without piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum deceleration boundary segments, respectively. Numerical examples for optimal configuration are provided, and the obtained results are compared with those obtained with Newton’s heat transfer law [q ∝△(T )]. The results also show that optimizing the piston motion can improve power and efficiency of the engine by more than 9%. This is primarily due to the decrease in heat leakage loss on the initial portion of the power stroke.

  14. Efficiency at maximum power output for an engine with a passive piston

    Science.gov (United States)

    Sano, Tomohiko G.; Hayakawa, Hisao

    2016-08-01

    Efficiency at maximum power (MP) output for an engine with a passive piston without mechanical controls between two reservoirs is studied theoretically. We enclose a hard core gas partitioned by a massive piston in a temperature-controlled container and analyze the efficiency at MP under a heating and cooling protocol without controlling the pressure acting on the piston from outside. We find the following three results: (i) The efficiency at MP for a dilute gas is close to the Chambadal-Novikov-Curzon-Ahlborn (CNCA) efficiency if we can ignore the sidewall friction and the loss of energy between a gas particle and the piston, while (ii) the efficiency for a moderately dense gas becomes smaller than the CNCA efficiency even when the temperature difference of the reservoirs is small. (iii) Introducing the Onsager matrix for an engine with a passive piston, we verify that the tight coupling condition for the matrix of the dilute gas is satisfied, while that of the moderately dense gas is not satisfied because of the inevitable heat leak. We confirm the validity of these results using the molecular dynamics simulation and introducing an effective mean-field-like model which we call the stochastic mean field model.

  15. Coupling effects in bilayer thick metal films perforated with rectangular nanohole arrays

    Directory of Open Access Journals (Sweden)

    Li Yuan

    2013-09-01

    Full Text Available The coupling effects in bilayer thick metal (silver films perforated with rectangular nanohole arrays are investigated using the finite-difference time-domain technique. Many interesting light phenomena are observed as the distance between the metal rectangular nanohole arrays varies. Coupling effects are found to play very important roles on the optical and electronic properties of bilayer metal rectangular nanohole arrays: antisymmetric coupling between surface plasmon polaritons near the top and bottom film plane, and antisymmetric coupling between localized surface plasmon resonances near the two long sides of the rectangular hole, are probably excited in each layer of bilayer metal rectangular nanohole arrays; antisymmetric and symmetric magnetic coupling probably occur between the metal rectangular nanohole arrays.

  16. Ultra-wideband ladder filters using zero-th shear mode plate wave in ultrathin LiNbO3 plate with apodized interdigital transducers

    Science.gov (United States)

    Kadota, Michio; Tanaka, Shuji

    2016-07-01

    There are two kinds of plate waves propagating in a thin plate, Lamb and shear horizontal (SH) waves. The former has a velocity higher than 15,000 m/s when the plate is very thin. On the contrary, 0th SH (SH0) mode plate wave in an ultrathin LiNbO3 plate has an electro-mechanical coupling factor larger than 50%. Authors fabricated an ultra-wideband T-type ladder filter with a relative bandwidth (BW) of 41% using the SH0 mode plate wave. Although the BW of the filter fully covers the digital TV band in Japan, it does not have sufficient margin at the lower and higher end of BW. Besides, periodic small ripples due to transverse mode in pass-band of the filter were observed. In this study π-type ladder filters were fabricated by changing the pitch ratio of interdigital transducer (IDT) of parallel and series arm resonators (PR(IDT)) to control the BW, and by apodizing IDTs to improve the periodic small ripples due to transverse mode. Ultra-wideband filters without periodic small transverse mode with ultrawide bandwidth from 41 to 49% were fabricated. The BWs fully cover ultrawide digital television bands in Japan and U.S.A. These filters with an ultrawide BW and a steep characteristic show the possibility to be applied to a reported cognitive radio system and other communication systems requiring an ultrawide BW.

  17. Optimal fitting of gaussian-apodized or under-resolved emission lines in Fourier Transform spectra providing new insights on the velocity structure of NGC 6720

    CERN Document Server

    Martin, Thomas B; Drissen, Laurent

    2016-01-01

    An analysis of the kinematics of NGC 6720 is performed on the commissioning data obtained with SITELLE, the Canada-France-Hawaii Telescope's new imaging Fourier transform spectrometer. In order to measure carefully the small broadening effect of a shell expansion on an unresolved emission line, we have determined a computationally robust implementation of the convolution of a Gaussian with a sinc instrumental line shape which avoids arithmetic overflows. This model can be used to measure line broadening of typically a few km/s even at low spectral resolution (R less than 5000). We have also designed the corresponding set of Gaussian apodizing functions that are now used by ORBS, the SITELLE's reduction pipeline. We have implemented this model in ORCS, a fitting engine for SITELLE's data, and used it to derive the [SII] density map of the central part of the nebula. The study of the broadening of the [NII] lines shows that the Main Ring and the Central Lobe are two different shells with different expansion vel...

  18. Optimal fitting of gaussian-apodized or under-resolved emission lines in Fourier Transform spectra providing new insights on the velocity structure of NGC 6720

    Science.gov (United States)

    Martin, Thomas B.; Prunet, Simon; Drissen, Laurent

    2016-09-01

    An analysis of the kinematics of NGC 6720 is performed on the commissioning data obtained with SITELLE, the Canada-France-Hawaii Telescope's new imaging Fourier transform spectrometer. In order to measure carefully the small broadening effect of a shell expansion on an unresolved emission line, we have determined a computationally robust implementation of the convolution of a Gaussian with a sinc instrumental line shape which avoids arithmetic overflows. This model can be used to measure line broadening of typically a few km s-1 even at low spectral resolution (R less than 5000). We have also designed the corresponding set of Gaussian apodizing functions that are now used by ORBS, the SITELLE's reduction pipeline. We have implemented this model in ORCS, a fitting engine for SITELLE's data, and used it to derive the [S II] density map of the central part of the nebula. The study of the broadening of the [N II] lines shows that the Main Ring and the Central Lobe are two different shells with different expansion velocities. We have also derived deep and spatially resolved velocity maps of the Halo in [N II] and Hα and found that the brightest bubbles are originating from two bipolar structures with a velocity difference of more than 35 km s-1 lying at the poles of a possibly unique Halo shell expanding at a velocity of more than 15 km s-1.

  19. Simplified nonlinear theory of the dielectric loaded rectangular Cerenkov maser

    Institute of Scientific and Technical Information of China (English)

    Zhao Ding; Ding Yao-Gen

    2012-01-01

    To rapidly and accurately investigate the performance of the dielectric loaded rectangular Cerenkov maser,a simplified nonlinear theory is proposed,in which the variations of wave amplitude and wave phase are determined by two coupled first-order differential equations.Through combining with the relativistic equation of motion and adopting the forward wave assumption,the evolutions of the forward wave power,the power growth rate,the axial wave number,the accumulated phase offset,and the information of the particle movement can be obtained in a single-pass calculation.For an illustrative example,this method is used to study the influences of the beam current,the gap distance between the beam and the dielectric surface,and the momentum spread on the forward wave.The variations of the saturated power and the saturation length with the working frequency for the beams with different momentum spreads have also been studied.The result shows that the beam-wave interaction is very sensitive to the electron beam state.To further verify this simplified theory,a comparison with the result produced from a rigorous method is also provided,we find that the evolution curves of the forward wave power predicted by the two methods exhibit excellent agreement.In practical applications,the developed theory can be used for the design and analysis of the rectangular Cerenkov maser.

  20. A Rectangular Planar Spiral Antenna for GIS Partial Discharge Detection

    Directory of Open Access Journals (Sweden)

    Xiaoxing Zhang

    2014-01-01

    Full Text Available A rectangular planar spiral antenna sensor was designed for detecting the partial discharge in gas insulation substations (GIS. It can expediently receive electromagnetic waves leaked from basin-type insulators and can effectively suppress low frequency electromagnetic interference from the surrounding environment. Certain effective techniques such as rectangular spiral structure, bow-tie loading, and back cavity structure optimization during the antenna design process can miniaturize antenna size and optimize voltage standing wave ratio (VSWR characteristics. Model calculation and experimental data measured in the laboratory show that the antenna possesses a good radiating performance and a multiband property when working in the ultrahigh frequency (UHF band. A comparative study between characteristics of the designed antenna and the existing quasi-TEM horn antenna was made. Based on the GIS defect simulation equipment in the laboratory, partial discharge signals were detected by the designed antenna, the available quasi-TEM horn antenna, and the microstrip patch antenna, and the measurement results were compared.

  1. Mechanical behavior analysis on electrostatically actuated rectangular microplates

    International Nuclear Information System (INIS)

    Microplates are widely used in various MEMS devices based on electrostatic actuation such as MEMS switches, micro pumps and capacitive micromachined ultrasonic transducers (CMUTs). Accurate predictions for the mechanical behavior of the microplate under electrostatic force are important not only for the design and optimization of these electrostatic devices but also for their operation. This paper presents a novel reduced-order model for electrostatically actuated rectangular and square microplates with a new method to treat the nonlinear electrostatic force. The model was developed using Galerkin method which turned the partial-differential equation governing the microplates into an ordinary equation system. Using this model and cosine-like deflection functions, explicit expressions were established for the deflection and pull-in voltage of the rectangular and square microplates. The theoretical results were well validated with the finite element method simulations and experimental data of literature. The expressions for the deflection analysis are able to predict the deflection up to the pull-in position with an error less than 5.0%. The expressions for the pull-in voltage analysis can determine the pull-in voltages with errors less than 1.0%. Additionally, the method to calculate the capacitance variation of the electrostatically actuated microplates was proposed. These theoretical analyses are helpful for design and optimization of electrostatically actuated microdevices. (paper)

  2. Measurement on the cavitating vortex shedding behind rectangular obstacles

    Energy Technology Data Exchange (ETDEWEB)

    Hegedus, F; Hos, C; Pandula, Z; Kullmann, L, E-mail: hegedusf@hds.bme.h [Department of Hydrodynamic Systems, Budapest University of Technology and Economics Muegyetem rkp. 1, Budapest 1111 (Hungary)

    2010-08-15

    Measurement results on the cavitating vortex shedding behind sharp-edged rectangular bodies are presented, intended to provide benchmark cases for the validation of unsteady cavitation models of CFD codes. Rectangular bodies of increasing aspect ratio (1, 2, 3 and 4) were used with a constant 25mm height (12.5% blockage ratio). The water velocity in the 0.2x0.05m test section of the channel was varied between 1 and 12 m/s resulting in a Reynolds number in the range of (0.4-3.5)x105. Pressure signals were measured at several locations, notably in the wake. Dominant frequencies and Strouhal numbers are reported from cavitation-free flow (classic von Karman vortex shedding) up to supercavitation as a function of the free-stream Reynolds number. The results are in good agreement with the literature in case of the square cylinder. We experienced a slight increase of the dominant Strouhal number with increasing aspect ratio. This result is somewhat inconsistent with the literature, in which a fall of the Strouhal number can be observed at side ratio 2. This may be the consequence of the different ranges of Reynolds numbers. It was also found that between the inception of cavitation and the formation of supercavitation the Strouhal number is not affected by cavitation.

  3. Effects of rectangular microchannel aspect ratio on laminar friction constant

    Science.gov (United States)

    Papautsky, Ian; Gale, Bruce K.; Mohanty, Swomitra K.; Ameel, Timothy A.; Frazier, A. Bruno

    1999-08-01

    In this paper, the effects of rectangular microchannel aspect ratio on laminar friction constant are described. The behavior of fluids was studied using surface micromachined rectangular metallic pipette arrays. Each array consisted of 5 or 7 pipettes with widths varying from 150 micrometers to 600 micrometers and heights ranging from 22.71 micrometers to 26.35 micrometers . A downstream port for static pressure measurement was used to eliminate entrance effects. A controllable syringe pump was used to provide flow while a differential pressure transducer was used to record the pressure drop. The experimental data obtained for water for flows at Reynolds numbers below 10 showed an approximate 20% increase in the friction constant for a specified driving potential when compared to macroscale predictions from the classical Navier-Stokes theory. When the experimental data are studied as a function of aspect ratio, a 20% increase in the friction constant is evident at low aspect ratios. A similar increase is shown by the currently available experimental data for low Reynolds number (flows of water.

  4. Efficient and accurate sound propagation using adaptive rectangular decomposition.

    Science.gov (United States)

    Raghuvanshi, Nikunj; Narain, Rahul; Lin, Ming C

    2009-01-01

    Accurate sound rendering can add significant realism to complement visual display in interactive applications, as well as facilitate acoustic predictions for many engineering applications, like accurate acoustic analysis for architectural design. Numerical simulation can provide this realism most naturally by modeling the underlying physics of wave propagation. However, wave simulation has traditionally posed a tough computational challenge. In this paper, we present a technique which relies on an adaptive rectangular decomposition of 3D scenes to enable efficient and accurate simulation of sound propagation in complex virtual environments. It exploits the known analytical solution of the Wave Equation in rectangular domains, and utilizes an efficient implementation of the Discrete Cosine Transform on Graphics Processors (GPU) to achieve at least a 100-fold performance gain compared to a standard Finite-Difference Time-Domain (FDTD) implementation with comparable accuracy, while also being 10-fold more memory efficient. Consequently, we are able to perform accurate numerical acoustic simulation on large, complex scenes in the kilohertz range. To the best of our knowledge, it was not previously possible to perform such simulations on a desktop computer. Our work thus enables acoustic analysis on large scenes and auditory display for complex virtual environments on commodity hardware. PMID:19590105

  5. Flux penetration into flat rectangular superconductors with anisotropic critical current

    International Nuclear Information System (INIS)

    Superconductors with anisotropic critical-current density jc exhibit characteristic anisotropic flux-density patterns during penetration of magnetic flux. We investigate this anisotropic flux penetration in detail by observations using the magneto-optical Faraday effect and by first-principles calculations which describe the superconductor as a nonlinear anisotropic conductor. Our samples are thin plates of DyBa2Cu3O7-δ into which anisotropic pinning is introduced by oblique irradiation with 340-MeV Xe ions creating linear defects. Excellent agreement between experiment and theory is obtained. In particular, we find that in rectangular plates with jc anisotropy equal to the side ratio, the intrinsic and shape anisotropies may compensate such that the flux pattern looks like that in an isotropic square stretched to the rectangular shape. This means the current streamlines are concentric rectangles which shrink to a point rather than to a line, and the discontinuity lines where the current bends sharply, coincide with the diagonals of the rectangle rather than forming the usual double-Y structure. copyright 1997 The American Physical Society

  6. A cross-corner effect in a rectangular sputtering magnetron

    International Nuclear Information System (INIS)

    Electron trajectories, ionization distribution, and magnetic field in a conventional rectangular sputtering magnetron cathode are simulated in order to understand the mechanism of a cross-corner effect, which is a common phenomenon associated with rectangular magnetron cathodes and which limits the target utilization. It is found that once the magnetic field in end region of the cathode is different from that in straightway, the cross-corner effect exists. Using a fourth-order Runge-Kutta method, the electron trajectories are simulated, showing that the electrons may drift much faster in the end region than in the straightway and pass quickly to cross-corner region. A Monte-Carlo method is employed to simulate ionization distribution and to quantitatively predict target erosion. The results show denser ionization in the cross-corner region, causing more intensive erosion in that area. We demonstrate that by properly modifying the magnet field in the end region, the electron drift velocity and ionization distribution can be controlled and the cross-corner effect may be significantly reduced

  7. Measurement strategy for rectangular electrical capacitance tomography sensor

    International Nuclear Information System (INIS)

    To investigate the influence of the measurement strategy for the rectangular electrical capacitance tomography (ECT) sensor, a Finite Element Method (FEM) is utilized to create the model for simulation. The simulation was carried out using COMSOL Multiphysics(trade mark, serif) and Matlab(trade mark, serif). The length-width ratio of the rectangular sensing area is 5. Twelve electrodes are evenly arranged surrounding the pipe. The covering ratio of the electrodes is 90%. The capacitances between different electrode pairs are calculated for a bar distribution. The air of the relative permittivity 1.0 and the material of the permittivity 3.0 are used for the calibration. The relative permittivity of the second phase is 3.0. The noise free and noise data are used for the image reconstruction using the Linear Back Projection (LBP). The measurement strategies with 1-, 2- and 4- electrode excitation are compared using the correlation coefficient. Preliminary results show that the measurement strategy with 2-electrode excitation outperforms other measurement strategies with 1- or 4-electrode excitation

  8. Versatile patterns of multiple rectangular noise-like pulses in a fiber laser.

    Science.gov (United States)

    Huang, Yu-Qi; Qi, You-Li; Luo, Zhi-Chao; Luo, Ai-Ping; Xu, Wen-Cheng

    2016-04-01

    We report on the generation of versatile patterns of multiple rectangular noise-like pulses (NLPs) in a fiber laser mode-locked by nonlinear amplifying loop mirror (NALM). Benefiting from the strengthened nonlinear effect of a segment of highly nonlinear fiber (HNLF) in the loop, multiple rectangular NLPs with various patterns are formed depending on the cavity parameter settings. In particular, the multiple rectangular NLPs could possess unequal packet durations, which is different from the conventional multi-soliton patterns. The experimental results contribute to further understanding the characteristics of the rectangular NLP and the dynamics of multi-pulse patterns. PMID:27137025

  9. Final design of a free-piston hydraulic advanced Stirling conversion system

    Science.gov (United States)

    Wallace, D. A.; Noble, J. E.; Emigh, S. G.; Ross, B. A.; Lehmann, G. A.

    1991-01-01

    Under the US Department of Energy's (DOEs) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for solar distributed receiver systems. The final design is described of an engineering prototype advanced Stirling conversion system (ASCS) with a free-piston hydraulic engine output capable of delivering about 25 kW of electric power to a utility grid. The free-piston Stirling engine has the potential for a highly reliable engine with long life because it has only a few moving parts, has noncontacting bearings, and can be hermetically sealed. The ASCS is designed to deliver maximum power per year over a range of solar input with a design life of 30 years (60,000 h). The system includes a liquid Nak pool boiler heat transport system and a free-piston Stirling engine with high-pressure hydraulic output, coupled with a bent axis variable displacement hydraulic motor and a rotary induction generator.

  10. A piston-rotaxane with two potential stripes: force transitions and yield stresses.

    Science.gov (United States)

    Sevick, Edith M; Williams, David R M

    2013-01-01

    We examine a rod piston-rotaxane system, where the positions of several mobile rings on the axle are controlled by an external force acting on one of the rings. This allows us to access the translational entropy of the rings. For a simple rotaxane molecule with an axle that has uniform ring-axle interactions along its length, the molecule behaves like a miniature piston filled with a one-dimensional ideal gas. We then examine the effect of two stripes on the axle, having different ring-axle interactions with the mobile rings, so that one section is of high energy (repulsive) for the rings and another section is of lower energy (or attractive). This kind of rotaxane can exhibit rapid changes in displacement or force, and in particular, this molecule can exhibit a yield stress in which the piston suddenly compresses under a small increase in the applied force. PMID:24177696

  11. A Piston-Rotaxane with Two Potential Stripes: Force Transitions and Yield Stresses

    Directory of Open Access Journals (Sweden)

    Edith M. Sevick

    2013-10-01

    Full Text Available We examine a rod piston-rotaxane system, where the positions of several mobile rings on the axle are controlled by an external force acting on one of the rings. This allows us to access the translational entropy of the rings. For a simple rotaxane molecule with an axle that has uniform ring-axle interactions along its length, the molecule behaves like a miniature piston filled with a one-dimensional ideal gas. We then examine the effect of two stripes on the axle, having different ring-axle interactions with the mobile rings, so that one section is of high energy (repulsive for the rings and another section is of lower energy (or attractive. This kind of rotaxane can exhibit rapid changes in displacement or force, and in particular, this molecule can exhibit a yield stress in which the piston suddenly compresses under a small increase in the applied force.

  12. Interring Gas Dynamic Analysis of Piston in a Diesel Engine considering the Thermal Effect

    Directory of Open Access Journals (Sweden)

    Wanyou Li

    2015-01-01

    Full Text Available Understanding the interaction between ring dynamics and gas transport in ring pack systems is crucial and needs to be imperatively studied. The present work features detailed interring gas dynamics of piston ring pack behavior in internal combustion engines. The model is developed for a ring pack with four rings. The dynamics of ring pack are simulated. Due to the fact that small changes in geometry of the grooves and lands would have a significant impact on the interring gas dynamics, the thermal deformation of piston has been considered during the ring pack motion analysis in this study. In order to get the temperature distribution of piston head more quickly and accurately, an efficient method utilizing the concept of inverse heat conduction is presented. Moreover, a sensitive analysis based on the analysis of partial regression coefficients is presented to investigate the effect of groove parameters on blowby.

  13. Efficiency of a new internal combustion engine concept with variable piston motion

    Directory of Open Access Journals (Sweden)

    Dorić Jovan Ž.

    2014-01-01

    Full Text Available This paper presents simulation of working process in a new IC engine concept. The main feature of this new IC engine concept is the realization of variable movement of the piston. With this unconventional piston movement it is easy to provide variable compression ratio, variable displacement and combustion during constant volume. These advantages over standard piston mechanism are achieved through synthesis of the two pairs of non-circular gears. Presented mechanism is designed to obtain a specific motion law which provides better fuel consumption of IC engines. For this paper Ricardo/WAVE software was used, which provides a fully integrated treatment of time-dependent fluid dynamics and thermodynamics by means of onedimensional formulation. The results obtained herein include the efficiency characteristic of this new heat engine concept. The results show that combustion during constant volume, variable compression ratio and variable displacement have significant impact on improvement of fuel consumption.

  14. Final design of a free-piston hydraulic advanced Stirling conversion system

    Science.gov (United States)

    Wallace, D. A.; Noble, J. E.; Emigh, S. G.; Ross, B. A.; Lehmann, G. A.

    Under the US Department of Energy's (DOEs) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for solar distributed receiver systems. The final design is described of an engineering prototype advanced Stirling conversion system (ASCS) with a free-piston hydraulic engine output capable of delivering about 25 kW of electric power to a utility grid. The free-piston Stirling engine has the potential for a highly reliable engine with long life because it has only a few moving parts, has noncontacting bearings, and can be hermetically sealed. The ASCS is designed to deliver maximum power per year over a range of solar input with a design life of 30 years (60,000 h). The system includes a liquid Nak pool boiler heat transport system and a free-piston Stirling engine with high-pressure hydraulic output, coupled with a bent axis variable displacement hydraulic motor and a rotary induction generator.

  15. Investigation into Piston-Slap Force under Friction and Connecting Rod Effects of Diesel Engine

    Directory of Open Access Journals (Sweden)

    Fuadi Noor Balia

    2011-01-01

    Full Text Available In this paper, a dynamics analysis of diesel engine through investigation of the piston-slap force by considering the friction and connecting rod effects is presented. A single-cylinder of 500 cc Diesel Engine’s mechanism was examined. The position, velocity and acceleration of the pins and the center of mass for each linkage were calculated by using vector analysis principles. The governing equations of the forces and moments were derived based on the Cartesian coordinate principles, and solved by using Gauss elimination method. Hence, the piston-slap force onto the cylinder wall under friction and connecting rod effects were determined. Favourable comparison with previously published work was performed and excellent agreement between the results was obtained. The result shows that the friction and connecting rod effects significantly influence to the piston-slap force.

  16. Flow effects due to valve and piston motion in an internal combustion engine exhaust port

    International Nuclear Information System (INIS)

    Highlights: • Flow regime identification depending on the valve lift during the exhaust stroke. • Analysis of the valve motion effect onto the flow development in the exhaust port. • Physical interpretation of commonly used discharge and flow coefficient formulations. • Illustration of flow effects in junction regions with pulsatile flow. - Abstract: Performance optimization regarding e.g. exhaust valve strategies in an internal combustion engine is often performed based on one-dimensional simulation investigation. Commonly, a discharge coefficient is used to describe the flow behavior in complex geometries, such as the exhaust port. This discharge coefficient for an exhaust port is obtained by laboratory experiments at fixed valve lifts, room temperatures, and low total pressure drops. The present study investigates the consequences of the valve and piston motion onto the energy losses and the discharge coefficient. Therefore, Large Eddy Simulations are performed in a realistic internal combustion geometry using three different modeling strategies, i.e. fixed valve lift and fixed piston, moving piston and fixed valve lift, and moving piston and moving valve, to estimate the energy losses. The differences in the flow field development with the different modeling approaches is delineated and the dynamic effects onto the primary quantities, e.g. discharge coefficient, are quantified. Considering the motion of piston and valves leads to negative total pressure losses during the exhaust cycle, which cannot be observed at fixed valve lifts. Additionally, the induced flow structures develop differently when valve motion is taken into consideration, which leads to a significant disparity of mass flow rates evolving through the two individual valve ports. However, accounting for piston motion and limited valve motion, leads to a minor discharge coefficient alteration of about one to two percent

  17. Effects of piston elastic deformation on piston secondary motion and skirt lubrication characteristics%活塞弹性变形对活塞二阶运动及裙部润滑特性的影响

    Institute of Scientific and Technical Information of China (English)

    阮登芳; 许金霞; 高鑫

    2015-01-01

    为揭示活塞弹性变形对活塞二阶运动及裙部润滑特性的影响规律,基于有限元法建立活塞和缸套的结构动力学模型,耦合活塞二阶运动方程及裙部流体动力润滑模型,分析活塞弹性对活塞二阶运动和裙部润滑特性的影响。结果表明:不同曲轴转角下活塞主、次推力面的变形不同,做功行程中变形明显,而且最大变形量出现的区域随曲轴转角的变化而改变;考虑活塞弹性变形后,活塞二阶运动一般比不考虑活塞弹性变形有所增加,在压缩和做功行程中增加明显;活塞裙部的最小油膜厚度增加,而总摩擦功耗降低,做功行程中两者变化明显;油膜压力场峰值出现位置及油膜压力分布规律改变,油膜压力场峰值减小。该研究为活塞裙部型线设计及配缸间隙选择提供参考。%Piston skirt-liner is one of the primary friction pairs influencing the friction power loss of an internal combustion engine, so it is feasible to improve the fuel economy of engines by studying the lubrication characteristics of the piston skirt-liner to reduce the friction power loss. The piston skirt lubrication is related to the piston secondary motion and the elastic deformation of the piston and liner, and there exists a strong coupled relationship between them. Therefore, it may be more reasonable to couple the elastic deformation equation of piston and liner than ignore the deformation of piston and liner, when the piston skirt lubrication and the piston secondary motion equations are solved. In order to reveal the effects of the piston elastic deformation on the piston secondary motion and skirt lubrication characteristics, the structural dynamics equations of the piston and liner were established based on the finite element modal reduction method, the piston secondary motion equation, the average Reynolds equation and the possible solid-to-solid contact equation in mixed lubrication

  18. An evenly loaded seal for the piston rod of the U8-6M drill pumps

    Energy Technology Data Exchange (ETDEWEB)

    Lishchinskiy, S.P.; Lakhnyuk, V.M.; Mardakhayev, A.A.

    1983-01-01

    The causes for the low service life of piston rod seals in drill pumps are analyzed. The design of a new UShN-80 piston rod seal is described. The results are cited of oilfield tests of the new seal which attest to its high efficiency and reliability.

  19. A systematic review of the effect of piston diameter in stapes surgery for otosclerosis on hearing results

    NARCIS (Netherlands)

    Wegner, Inge; Verhagen, Jessica J; Stegeman, Inge; Vincent, Robert; Grolman, Wilko

    2015-01-01

    OBJECTIVE: To evaluate the effect of piston diameter in primary stapedotomy for otosclerosis patients measured by hearing outcome. DATA SOURCES: PubMed, Embase, and the Cochrane Library. REVIEW METHODS: A systematic search was conducted. Studies reporting original data on the effect of piston diamet

  20. A Piston-Rotaxane with Two Potential Stripes: Force Transitions and Yield Stresses

    OpenAIRE

    Edith M. Sevick; David R.M. Williams

    2013-01-01

    We examine a rod piston-rotaxane system, where the positions of several mobile rings on the axle are controlled by an external force acting on one of the rings. This allows us to access the translational entropy of the rings. For a simple rotaxane molecule with an axle that has uniform ring-axle interactions along its length, the molecule behaves like a miniature piston filled with a one-dimensional ideal gas. We then examine the effect of two stripes on the axle, having different ring-axle i...

  1. A feasibility assessment of magnetic bearings for free-piston Stirling space power converters

    Energy Technology Data Exchange (ETDEWEB)

    Curwen, P.W.; Rao, D.K.; Wilson, D.S. [Mechanical Technology Inc., Latham, NY (United States)

    1992-06-01

    This report describes work performed by Mechanical Technology Incorporated (MTI) under NASA Contract NAS3-26061, {open_quotes}A Feasibility Assessment of Magnetic Bearings for Free-Piston Stirling Space Engines.{close_quotes} The work was performed over the period from July 1990 through August 1991. The objective of the effort was to assess the feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery of the type currently being evaluated for possible use in future long-term space missions.

  2. Numerical investigations of Piston mode resonance in a moonpool using OpenFOAM

    OpenAIRE

    Alsgaard, Jørgen Andreas

    2010-01-01

    Moonpool dynamics is a complex phenomenon, and is part of a series of problems referred to as gap problems involving entrapped fluid in a small gap. The fluid in these gaps has an infinite number of resonance modes; a piston mode resonance in heave, and an infinite number of sloshing modes. The piston mode is often the most troublesome, and must be considered when designing a moonpool. A numerical verification is done on an experiment of a 2D section of a moonpool in shallow water. The numeri...

  3. Compression of helium to high pressures and temperatures using a ballistic piston apparatus

    Science.gov (United States)

    Roman, B. P.; Rovel, G. P.; Lewis, M. J.

    1971-01-01

    Some preliminary experiments are described which were carried out in a high enthalpy laboratory to investigate the compression of helium, a typical shock-tube driver gas, to very high pressures and temperatures by means of a ballistic piston. The purpose of these measurements was to identify any problem areas in the compression process, to determine the importance of real gas effects duDC 47355s process, and to establish the feasibility of using a ballistic piston apparatus to achieve temperatures in helium in excess of 10,000 K.

  4. A feasibility assessment of magnetic bearings for free-piston Stirling space power converters

    International Nuclear Information System (INIS)

    This report describes work performed by Mechanical Technology Incorporated (MTI) under NASA Contract NAS3-26061, open-quotes A Feasibility Assessment of Magnetic Bearings for Free-Piston Stirling Space Engines.close quotes The work was performed over the period from July 1990 through August 1991. The objective of the effort was to assess the feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery of the type currently being evaluated for possible use in future long-term space missions

  5. A transient tribodynamic approach for the calculation of internal combustion engine piston slap noise

    Science.gov (United States)

    Dolatabadi, N.; Littlefair, B.; De la Cruz, M.; Theodossiades, S.; Rothberg, S. J.; Rahnejat, H.

    2015-09-01

    An analytical/numerical methodology is presented to calculate the radiated noise due to internal combustion engine piston impacts on the cylinder liner through a film of lubricant. Both quasi-static and transient dynamic analyses coupled with impact elasto-hydrodynamics are reported. The local impact impedance is calculated, as well as the transferred energy onto the cylinder liner. The simulations are verified against experimental results for different engine operating conditions and for noise levels calculated in the vicinity of the engine block. Continuous wavelet signal processing is performed to identify the occurrence of piston slap noise events and their spectral content, showing good conformance between the predictions and experimentally acquired signals.

  6. The effect of electrode material on the motion of a plasma piston in rail accelerators

    Science.gov (United States)

    Bobashev, S. V.; Zhukov, B. G.; Kurakin, R. O.; Ponyaev, S. A.; Reznikov, B. I.

    2015-10-01

    The acceleration of a plasma piston in the channels of rail accelerators with copper and graphite electrodes is studied experimentally. It is found that the plasma velocity is reduced by 15-20% (at equal discharge currents) when graphite electrodes are used instead of copper ones. This may be attributed to an increase in the erosion graphite mass that is drawn into motion by the plasma piston. It is concluded based on the interpretation of the obtained data that the current flow in the channels of rail accelerators is governed at high plasma speeds by the processes of thermoautoelectron emission.

  7. Influence of piston displacement on the scavenging and swirling flow in two-stroke diesel engines

    OpenAIRE

    Obeidat, Anas; Haider, Sajjad; Ingvorsen, Kristian Mark; Meyer, Knud Erik; Walther, Jens Honore

    2012-01-01

    We study the effect of piston motion on the in-cylinder swirling flow in a low speed, large two-stroke marine diesel engine. The work involves experimental, and numerical simulation using OpenFOAM platform, Large Eddy Simulation was used with three different models, One equation Eddy, Dynamic One equation Eddy, and Ta Phouc Loc model, to study the transient phenomena of the flow. The results are conducted at six cross sectional planes along the axis of the cylinder and with the piston displac...

  8. Separation of combustion noise and piston-slap in diesel engine—Part II: Separation of combustion noise and piston-slap using blind source separation methods

    Science.gov (United States)

    Servière, C.; Lacoume, J.-L.; El Badaoui, M.

    2005-11-01

    This paper is devoted to blind separation of combustion noise and piston-slap in diesel engines. The two phenomena are recovered only from signals issued from accelerometers placed on one of the cylinders. A blind source separation (BSS) method is developed, based on a convolutive model of non-stationary mixtures. We introduce a new method based on the joint diagonalisation of the time varying spectral matrices of the observation records and a new technique to handle the problem of permutation ambiguity in the frequency domain. This method is then applied to real data and the estimated sources are validated by several physical arguments. So, the contribution of the piston-slap and the combustion noise can be recovered for all the sensors. The energy of the two phenomena can then be given with regards to the position of the accelerometers.

  9. Round versus rectangular: Does the plot shape matter?

    Science.gov (United States)

    Iserloh, Thomas; Bäthke, Lars; Ries, Johannes B.

    2016-04-01

    Field rainfall simulators are designed to study soil erosion processes and provide urgently needed data for various geomorphological, hydrological and pedological issues. Due to the different conditions and technologies applied, there are several methodological aspects under review of the scientific community, particularly concerning design, procedures and conditions of measurement for infiltration, runoff and soil erosion. Extensive discussions at the Rainfall Simulator Workshop 2011 in Trier and the Splinter Meeting at EGU 2013 "Rainfall simulation: Big steps forward!" lead to the opinion that the rectangular shape is the more suitable plot shape compared to the round plot. A horizontally edging Gerlach trough is installed for sample collection without forming unnatural necks as is found at round or triangle plots. Since most research groups did and currently do work with round plots at the point scale (<1m²), a precise analysis of the differences between the output of round and square plots are necessary. Our hypotheses are: - Round plot shapes disturb surface runoff, unnatural fluvial dynamics for the given plot size such as pool development especially directly at the plot's outlet occur. - A square plot shape prevent these problems. A first comparison between round and rectangular plots (Iserloh et al., 2015) indicates that the rectangular plot could indeed be the more suitable, but the rather ambiguous results make a more elaborate test setup necessary. The laboratory test setup includes the two plot shapes (round, square), a standardised silty substrate and three inclinations (2°, 6°, 12°). The analysis of the laboratory test provide results on the best performance concerning undisturbed surface runoff and soil/water sampling at the plot's outlet. The analysis of the plot shape concerning its influence on runoff and erosion shows that clear methodological standards are necessary in order to make rainfall simulation experiments comparable. Reference

  10. Incompressible Laminar Flow Over a Three-Dimensional Rectangular Cavity

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper investigates unsteady incompressible flow over cavities,Previous research in in compressible cavity-flow has included flow inside and past a 2-dimensional cavity,and flow inside a 3-dimensional cavity,driven by a moving lid.The present research is focused on incompressible flow past a 3-dimensional open shallow cavity.This involves the complex interaction etween the external flow and the re-circulating flow within the cavity.In particular,computation was performed on a 3-dimensonal shallow rectangular cavity with a laminar boundary layer at the cavity and a Reynolds number of 5,000 and 10,000,respectively,A CFD approach,based on the unsteady Navier-Stokes equation for 3-dimensional incompressible flow,was used in the study.Typical results of the computation are presented.Theses results reveal the highly unsteady and complex vortical structures at high Reynolds numbers.

  11. Investigation on Properties of BGO Rectangular Detector Units for PET

    Institute of Scientific and Technical Information of China (English)

    QiHuirong; XiaoGuoqing; WangJinchuan; ZhanWenlong; GuoZhongyan; XuHushan; SunZhiyu; LiJiaxing; WangMeng; MaoRuishi; LiChen; ChenZHiqiang; ChenLixin; LiWenfei; ZhaoTiecheng; WuLijie; XuZhiguo

    2003-01-01

    Bi4Ge3O12 (BGO) is a commonly used scintillating crystal for Positron Emission Tomography detector (PET) due to its relatively high Z and high density. In order to finalize the crystal size of BGO block unit for our PET system, the detection efficiency, energy resolution and the linearity have been studied for three types of BGO rectangular detector units with the dimension of 20×20×10mm3, 20×20×20mm3 and 20×20×30mm3 respectively. The light from the BGO is readout by the photomultiplier of HAMAMATSU R1213 of which, peak sensitivity matches well with wavelength of the maximal emission of the crystal.

  12. Vibrations of cantilevered shallow cylindrical shells of rectangular planform

    Science.gov (United States)

    Leissa, A. W.; Lee, J. K.; Wang, A. J.

    1981-01-01

    A cantilevered, shallow shell of circular cylindrical curvature and rectangular planform exhibits free vibration behavior which differs considerably from that of a cantilevered beam or of a flat plate. Some numerical results can be found for the problem in the previously published literature, mainly obtained by using various finite element methods. The present paper is the first definitive study of the problem, presenting accurate non-dimensional frequency parameters for wide ranges of aspect ratio, shallowness ratio and thickness ratio. The analysis is based upon shallow shell theory. Numerical results are obtained by using the Ritz method, with algebraic polynomial trial functions for the displacements. Convergence is investigated, with attention being given both to the number of terms taken for each co-ordinate direction and for each of the three components of displacement. Accuracy of the results is also established by comparison with finite element results for shallow shells and with other accurate flat plate solutions.

  13. The refined theory of transversely isotropic piezoelectric rectangular beams

    Institute of Scientific and Technical Information of China (English)

    GAO; Yang; WANG; Minzhong

    2006-01-01

    The problem of deducing one-dimensional theory from two-dimensional theory for a transversely isotropic piezoelectric rectangular beam is investigated. Based on the piezoelasticity theory, the refined theory of piezoelectric beams is derived by using the general solution of transversely isotropic piezoelasticity and Lur'e method without ad hoc assumptions. Based on the refined theory of piezoelectric beams, the exact equations for the beams without transverse surface loadings are derived, which consist of two governing differential equations: the fourth-order equation and the transcendental equation. The approximate equations for the beams under transverse loadings are derived directly from the refined beam theory. As a special case, the governing differential equations for transversely isotropic elastic beams are obtained from the corresponding equations of piezoelectric beams. To illustrate the application of the beam theory developed, a uniformly loaded and simply supported piezoelectric beam is examined.

  14. Flutter Speed Limits of Cantilever Rectangular and Tapered Plates

    Directory of Open Access Journals (Sweden)

    Kusay H. Jabir

    2007-01-01

    Full Text Available The aerodynamic and elastic forces may cause an oscillation of the structure such as the high frequency of the airfoil surfaces and the dynamic instability occurring in an aircraft in flight and failure may occur at a speed called flutter speed. In this work, analytical and numerical investigations of flutter limits of thin plates have been carried out. The flutter speed of rectangular plates were obtained and compared with some published results. Different design parameters were investigated such as aspect ratio, thickness and their effects on flutter velocity. It was found that the structural mode shape plays an important role in the determination of the flutter speed and the coupling between the bending and torsional mode is the main cause of flutter.

  15. Oscillating laminar electrokinetic flow in infinitely extended rectangular microchannels.

    Science.gov (United States)

    Yang, J; Bhattacharyya, A; Masliyah, J H; Kwok, D Y

    2003-05-01

    This paper has addressed analytically the problem of laminar flow in microchannels with rectangular cross-section subjected to a time-dependent sinusoidal pressure gradient and a sinusoidal electric field. The analytical solution has been determined based on the Debye-Hückel approximation of a low surface potential at the channel wall. We have demonstrated that Onsager's principle of reciprocity is valid for this problem. Parametric studies of streaming potential have shown the dependence of the electroviscous effect not only on the Debye length, but also on the oscillation frequency and the microchannel width. Parametric studies of electroosmosis demonstrate that the flow rate decreases due to an increase in frequency. The obtained solutions for both the streaming potential and electroosmotic flows become those for flow between two parallel plates in the limit of a large aspect ratio. PMID:12725820

  16. Polyphase (non-resonant) multipactor in rectangular waveguides

    International Nuclear Information System (INIS)

    The polyphase multipactor, i.e. the non-resonant form of secondary electron emission rf discharges in vacuum, has been analysed and studied experimentally. The multipactor discharge was observed in an evacuated standard rectangular waveguide through which pulsed high-power microwave radiation in the decimeter wavelength range was transmitted. The power interval in which the two-sided (between the wide walls of the waveguide) multipactor appeared has been determined. It is found that there is a characteristic delay time for the onset of the multipactor breakdown as compared with the time at which the microwave power is applied. The dependence of this delay time on the microwave power has been established. The experimental results are compared with results of numerical simulations which make it possible to estimate the secondary emission properties of the waveguide walls. Reasons for some observed discrepancies between numerical results and experimental data are discussed as well as the nature of the observed multipactor delay

  17. Free Vibration Analysis of Rectangular Orthotropic Membranes in Large Deflection

    Directory of Open Access Journals (Sweden)

    Zheng Zhou-Lian

    2009-01-01

    Full Text Available This paper reviewed the research on the vibration of orthotropic membrane, which commonly applied in the membrane structural engineering. We applied the large deflection theory of membrane to derive the governing vibration equations of orthotropic membrane, solved it, and obtained the power series formula of nonlinear vibration frequency of rectangular membrane with four edges fixed. The paper gave the computational example and compared the two results from the large deflection theory and the small one, respectively. Results obtained from this paper provide some theoretical foundation for the measurement of pretension by frequency method; meanwhile, the results provide some theoretical foundation for the research of nonlinear vibration of membrane structures and the response solving of membrane structures under dynamic loads.

  18. Rectangular Waveguide HOM Couplers for a TESLA Superstructure

    CERN Document Server

    Blednykh, A; Kaljuzhny, V E; Lalayan, M; Milovanov, O S; Ponomarenko, A G; Sobenin, N; Sulimov, A; Trubin, D; Zavadtsev, A A; Dohlus, M

    2000-01-01

    Some modifications of a Rectangular Waveguide HOM couplers for TESLA superstructure have been investigated. These RWG HOM couplers are to be installed between the cavities of the superstructure and also at the both ends of it. We investigated a RWG HOM coupler attached to the beam pipe through the slots orientated along beam pipe axis (longitudinal slots), perpendicular to it (azimutal slots) and at some angle to this axis. For dipole modes of both polarizations damping two RWG in every design were used. This paper presents the results obtained for scaled-up setup at 3 GHz at room temperature. The advantages of HOM coupler with longitudinal slots for damping dipole modes and compact HOM coupler with slots at some angle to the axis are shown. Arrangement of HOM coupler in cryostat and heating due to HOM and FM losses are presented. Calculations and design of the feeding RWG coupler for superstructure are also presented.

  19. Experimental Study of Near Wake Flow Behind a Rectangular Cylinder

    Directory of Open Access Journals (Sweden)

    Abdollah Shadaram

    2008-01-01

    Full Text Available The turbulence characteristics of the near wake flow behind a rectangular cylinder is investigated in a two-dimensional analysis using a hot-wire anemometer. The time-averaged and fluctuating components of the velocity are measured for a cylinder having various width-to-height (b h-1 ratios. The measurements are carried out in a low-speed wind tunnel. Data from hot-wire anemometer is collected by a data acquisition system. The results show that the turbulence intensity in the flow wake decreases as the width-to-height ratio of the cylinder increases. In addition, the characteristics of the flow field in a few sections are evaluated. Spectral analysis of the velocity signals is carried out for two different Reynolds numbers. The spectral analysis shows that Strouhal number remains nearly constant in high Reynolds numbers. The results of present experiments are in close agreement with the most widely accepted results in the literature.

  20. Stability Analysis of Nonuniform Rectangular Beams Using Homotopy Perturbation Method

    Directory of Open Access Journals (Sweden)

    Seval Pinarbasi

    2012-01-01

    Full Text Available The design of slender beams, that is, beams with large laterally unsupported lengths, is commonly controlled by stability limit states. Beam buckling, also called “lateral torsional buckling,” is different from column buckling in that a beam not only displaces laterally but also twists about its axis during buckling. The coupling between twist and lateral displacement makes stability analysis of beams more complex than that of columns. For this reason, most of the analytical studies in the literature on beam stability are concentrated on simple cases: uniform beams with ideal boundary conditions and simple loadings. This paper shows that complex beam stability problems, such as lateral torsional buckling of rectangular beams with variable cross-sections, can successfully be solved using homotopy perturbation method (HPM.

  1. Estimating the magnetization distribution within rectangular rock samples

    Science.gov (United States)

    Reis, A. L. A.; Oliveira, V. C.; Yokoyama, E.; Bruno, A. C.; Pereira, J. M. B.

    2016-08-01

    Over the last decades, scanning magnetic microscopy techniques have been increasingly used in paleomagnetism and rock magnetism. Different from standard paleomagnetic magnetometers, scanning magnetic microscopes produce high-resolution maps of the vertical component of the magnetic induction field (flux density) on a plane located over the sample. These high-resolution magnetic maps can be used for estimating the magnetization distribution within a rock sample by inversion. Previous studies have estimated the magnetization distribution within rock samples by inverting the magnetic data measured on a single plane above the sample. Here we present a new spatial domain method for inverting the magnetic induction measured on four planes around the sample in order to retrieve its internal magnetization distribution. We have presumed that the internal magnetization distribution of the sample varies along one of its axes. Our method approximates the sample geometry by an interpretation model composed of a one-dimensional array of juxtaposed rectangular prisms with uniform magnetization. The Cartesian components of the magnetization vector within each rectangular prism are the parameters to be estimated by solving a linear inverse problem. Our method automatically deals with the averaging of the measured magnetic data due to the finite size of the magnetic sensor, preventing the application of a deconvolution before the inversion. Tests with synthetic data show the performance of our method in retrieving complex magnetization distributions even in the presence of magnetization heterogeneities. Moreover, they show the advantage of inverting the magnetic data on four planes around the sample and how this new acquisition scheme improves the estimated magnetization distribution within the rock sample. We have also applied our method to invert experimentally measured magnetic data produced by a highly magnetized synthetic sample that was manufactured in the laboratory. The

  2. Quantitative study of rectangular waveguide behavior in the THz.

    Energy Technology Data Exchange (ETDEWEB)

    Rowen, Adam M.; Nordquist, Christopher Daniel; Wanke, Michael Clement

    2009-10-01

    This report describes our efforts to quantify the behavior of micro-fabricated THz rectangular waveguides on a configurable, robust semiconductor-based platform. These waveguides are an enabling technology for coupling THz radiation directly from or to lasers, mixers, detectors, antennas, and other devices. Traditional waveguides fabricated on semiconductor platforms such as dielectric guides in the infrared or co-planar waveguides in the microwave regions, suffer high absorption and radiative losses in the THz. The former leads to very short propagation lengths, while the latter will lead to unwanted radiation modes and/or crosstalk in integrated devices. This project exploited the initial developments of THz micro-machined rectangular waveguides developed under the THz Grand Challenge Program, but instead of focusing on THz transceiver integration, this project focused on exploring the propagation loss and far-field radiation patterns of the waveguides. During the 9 month duration of this project we were able to reproduce the waveguide loss per unit of length in the waveguides and started to explore how the loss depended on wavelength. We also explored the far-field beam patterns emitted by H-plane horn antennas attached to the waveguides. In the process we learned that the method of measuring the beam patterns has a significant impact on what is actually measured, and this may have an effect on most of the beam patterns of THz that have been reported to date. The beam pattern measurements improved significantly throughout the project, but more refinements of the measurement are required before a definitive determination of the beam-pattern can be made.

  3. Experimental study of non-rectangular piano key weir discharge coefficient

    Directory of Open Access Journals (Sweden)

    Saleh I. Khassaf, Mohamed B. Al-Baghdadi

    2015-01-01

    Full Text Available Experimental investigation has been performed to understand the hydraulic behaviour of non-rectangular piano key weir where either the side wall angle or the side wall inclination angle is greater than zero. Five physical models were prepared: one standard type-A rectangular model, and four non-rectangular models designed in similar dimensions to the rectangular one. Tests were conducted in a 15m long, 0.3m wide and 0.45 m deep rectangular glass-walled experimental flume. Effects of side wall angle and side wall inclination angle on discharge coefficient were investigated, so that the head-discharge relationship for each model is achieved. It was concluded that changing those angle to about 10° has negative effect on discharge capacity, while changing them around 5° can increase the capacity when appropriate change in the inlet and outlet keys widths ratio.

  4. Fabrication of membrane-type microvalves in rectangular microfluidic channels via seal photopolymerization.

    Science.gov (United States)

    Park, Wook; Han, Sangkwon; Kwon, Sunghoon

    2010-10-21

    Rectangular fluidic channels have rarely been used in microfluidic devices which use PDMS membrane-type microvalves, since the rectangular channel shape does not perfectly match the round shape of the membrane deformation. We present a polymer sealing method to fabricate PDMS membrane-type microvalves for rectangular microchannels. After fabricating the microfluidic device, photocurable oligomer is introduced into the fluidic channel and gas pressure is applied to the pneumatic channel to deform the membrane. The polymer seal is then locally polymerized by photolithography producing a structure matching the shape of the deformed membrane curvature. We compare the flow leakage between the membrane-type microvalve with and without a polymer seal. We also demonstrate a micropump and droplet generator using this embedded polymer membrane-type microvalve in a rectangular microfluidic channel. This polymeric seal technique enables the use of easily fabricated rectangular channel membrane microvalves with all the functionality of their curved channel counterparts with negligible flow leakage. PMID:20721367

  5. Finite element fatigue analysis of rectangular clutch spring of automatic slack adjuster

    Science.gov (United States)

    Xu, Chen-jie; Luo, Zai; Hu, Xiao-feng; Jiang, Wen-song

    2015-02-01

    The failure of rectangular clutch spring of automatic slack adjuster directly affects the work of automatic slack adjuster. We establish the structural mechanics model of automatic slack adjuster rectangular clutch spring based on its working principle and mechanical structure. In addition, we upload such structural mechanics model to ANSYS Workbench FEA system to predict the fatigue life of rectangular clutch spring. FEA results show that the fatigue life of rectangular clutch spring is 2.0403×105 cycle under the effect of braking loads. In the meantime, fatigue tests of 20 automatic slack adjusters are carried out on the fatigue test bench to verify the conclusion of the structural mechanics model. The experimental results show that the mean fatigue life of rectangular clutch spring is 1.9101×105, which meets the results based on the finite element analysis using ANSYS Workbench FEA system.

  6. Disentangling rectangularization and life span extension with the moving rectangle method

    DEFF Research Database (Denmark)

    Schalkwijk, Frank H; Koopman, Jacob J E; Ghariq, Eidrees;

    2016-01-01

    PURPOSE: The moving rectangle method is used to disentangle the contributions of rectangularization and life span extension to the increase in life expectancy. It requires the choice of an endpoint of the survival curve that approaches the maximum age at death. We examined the effect of choosing...... of rectangularization and life span extension to the increase in life expectancy were calculated using the moving rectangle method. RESULTS: The choice of different survival values as end points profoundly influenced the estimated contributions of rectangularization and life span extension to the increase in life...... expectancy. When choosing 0.001, rectangularization contributed most years, whereas when choosing 0.1, life span extension contributed most years. CONCLUSIONS: When the moving rectangle method is used to estimate the contributions of rectangularization and life span extension to the increase in life...

  7. Apodization in high-contrast long-slit spectroscopy. II. Concept validation and first on-sky results with VLT/SPHERE

    Science.gov (United States)

    Vigan, A.; N'Diaye, M.; Dohlen, K.; Beuzit, J.-L.; Costille, A.; Caillat, A.; Baruffolo, A.; Blanchard, P.; Carle, M.; Ferrari, M.; Fusco, T.; Gluck, L.; Hugot, E.; Jaquet, M.; Langlois, M.; Le Mignant, D.; Llored, M.; Madec, F.; Mouillet, D.; Origné, A.; Puget, P.; Salasnich, B.; Sauvage, J.-F.

    2016-02-01

    Spectral characterization of young, giant exoplanets detected by direct imaging is one of the tasks of the new generation of high-contrast imagers. For this purpose, the VLT/SPHERE instrument includes a unique long-slit spectroscopy (LSS) mode coupled with Lyot coronagraphy in its infrared dual-band imager and spectrograph (IRDIS). The performance of this mode is intrinsically limited by the use of a non-optimal coronagraph, but in a previous work we demonstrated that it could be significantly improved at small inner-working angles using the stop-less Lyot coronagraph (SLLC). We now present the development, testing, and validation of the first SLLC prototype for VLT/SPHERE. Based on the transmission profile previously proposed, the prototype was manufactured using microdots technology and was installed inside the instrument in 2014. The transmission measurements agree well with the specifications, except in the very low transmissions (data acquired on the internal source. In imaging, we obtain a raw contrast gain of a factor 10 at 0.3'' and 5 at 0.5'' with the SLLC. Using data acquired with a focal-plane mask, we also demonstrate that no Lyot stop is required to reach the full performance, which validates the SLLC concept. Comparison with a realistic simulation model shows that we are currently limited by the internal phase aberrations of SPHERE. In spectroscopy, we obtain a gain of ~1 mag in a limited range of angular separations. Simulations show that although the main limitation comes from phase errors, the performance in the non-SLLC case is very close to the ultimate limit of the LSS mode. Finally, we obtain the very first on-sky data with the SLLC, which appear extremely promising for the future scientific exploitation of an apodized LSS mode in SPHERE.

  8. The Development of a Control System for a 5 Kilowatt Free Piston Stirling Engine Convertor

    Science.gov (United States)

    Kirby, Raymond L.; Vitale, Nick

    2008-01-01

    The new NASA Vision for Exploration, announced by President Bush in January 2004, proposes an ambitious program that plans to return astronauts to the moon by the 2018 time frame. A recent NASA study entitled "Affordable Fission Surface Power Study" recommended a 40 kWe, 900 K, NaK-cooled, Stirling convertors for 2020 launch. Use of two of the nominal 5 kW convertors allows the system to be dynamically balanced. A group of four dual-convertor combinations that would yield 40 kWe can be tested to validate the viability of Stirling technology for space fission surface power systems. The work described in this paper deals specifically with the control system for the 5 kW convertor described in the preceding paragraph. This control system is responsible for maintaining piston stroke to a setpoint in the presence of various disturbances including electrical load variations. Pulse starting of the Free Piston Stirling Engine (FPSE) convertor is also an inherent part of such a control system. Finally, the ability to throttle the engine to match the required output power is discussed in terms of setpoint control. Several novel ideas have been incorporated into the piston stroke control strategy that will engender a stable response to disturbances in the presence of midpoint drift while providing useful data regarding the position of both the power piston and displacer.

  9. Influence of piston displacement on the scavenging and swirling flow in two-stroke diesel engines

    DEFF Research Database (Denmark)

    Obeidat, Anas; Haider, Sajjad; Ingvorsen, Kristian Mark;

    We study the effect of piston motion on the in-cylinder swirling flow in a low speed, large two-stroke marine diesel engine. The work involves experimental, and numerical simulation using OpenFOAM platform, Large Eddy Simulation was used with three different models, One equation Eddy, Dynamic One...

  10. Multi-dimensional scavenging analysis of a free-piston linear alternator based on numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Jinlong; Zuo, Zhengxing; Li, Wen; Feng, Huihua [School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081 (China)

    2011-04-15

    A free-piston linear alternator (FPLA) is being developed by the Beijing Institute of Technology to improve the thermal efficiency relative to conventional crank-driven engines. A two-stroke scavenging process recharges the engine and is crucial to realizing the continuous operation of a free-piston engine. In order to study the FPLA scavenging process, the scavenging system was configured using computational fluid dynamics. As the piston dynamics of the FPLA are different to conventional crank-driven two-stroke engines, a time-based numerical simulation program was built using Matlab to define the piston's motion profiles. A wide range of design and operating options were investigated including effective stroke length, valve overlapping distance, operating frequency and charging pressure to find out their effects on the scavenging performance. The results indicate that a combination of high effective stroke length to bore ratio and long valve overlapping distance with a low supercharging pressure has the potential to achieve high scavenging and trapping efficiencies with low short-circuiting losses. (author)

  11. Integration of Gas Nitrocarburising and Oxidising in a Mass Production Line for Brake Pistons

    Institute of Scientific and Technical Information of China (English)

    Gero Walkowiak; Dieter M(u)ller; Uwe Zeibig

    2004-01-01

    The combination of wear- and corrosion resistance is a demand to a multitude of automotive parts. Several metallic coatings as hard/soft chromium or electroless nickel have been the conventional surface protection e.g. on parts as brake pistons and shock absorber or gas spring piston rods. The Corr-I-Dur(R) process - a special gasnitrocarburising and oxidising technology - has a huge potential not only in substituting those coatings but also in delivering surfaces with higher quality.The benefits of the replacement of soft chromium with Corr-I-Dur(R) and the implementation of the process in the customers production line with an annual capacity of 17 million brake pistons is described in this presentation. Starting with the demands on wear- and corrosion resistance the way of process development and the design of applicative equipment is shown. The result is a tailor-made surface solution with superior quality for deep drawn brake pistons. Two main disadvantagesoutgassing of the chromium layer and reduced corrosion resistance on the inner diameter - are eliminated by the replacement with Corr-I-Dur(R). The process-sure achievement of enhanced corrosion resistance, uniform layer thickness, negligible distortion as well as environmental and economical advantages make Corr-I-Dur(R) an excellence choice for this application.

  12. Stochastic stability assessment of a semi-free piston engine generator concept

    Science.gov (United States)

    Kigezi, T. N.; Gonzalez Anaya, J. A.; Dunne, J. F.

    2016-09-01

    Small engines, as power generators with low-noise and vibration characteristics, are needed in two niche application areas: as electric vehicle range extenders and as domestic micro Combined Heat and Power systems. A recent semi-free piston design known as the AMOCATIC generator fully meets this requirement. The engine potentially allows for high energy conversion efficiencies at resonance derived from having a mass and spring assembly. As with free-piston engines in general, stability and control of piston motion has been cited as the prime challenge limiting the technology's widespread application. Using physical principles, we derive in this paper two important results: an energy balance criterion and a related general stability criterion for a semi-free piston engine. Control is achieved by systematically designing a Proportional Integral (PI) controller using a control-oriented engine model for which a specific stability condition is stated. All results are presented in closed form throughout the paper. Simulation results under stochastic pressure conditions show that the proposed energy balance, stability criterion, and PI controller, operate as predicted to yield stable engine operation at fixed compression ratio.

  13. Investigation into piston-slap-induced vibration for engine condition simulation and monitoring

    Science.gov (United States)

    Geng, Z.; Chen, J.

    2005-04-01

    Piston slap is a common impact phenomenon existing in the reciprocating engine. It is also a major cause of the complex transient vibration response related to the impact excitation inside the engine. In order to correlate the piston-slap impact with the slap-induced vibration and consequently find out an effective approach for the engine dynamic behaviour simulation and working condition monitoring, an in-depth investigation from theoretical modelling to experimental verification is made in this paper. Firstly, the piston-slap phenomenon inside the reciprocating engine is briefly discussed from the viewpoint of engine mechanics. Based upon this, a nonlinear model is developed to simulate the slap-induced vibration response. Using numerical integration procedure, the slap-induced vibration response and its correlation with the inner-cylinder piston-slap impact are reasonably evaluated. Guided by the simulating results and, by introducing a fast wavelet-packet decomposition and reconstruction algorithm, a specially designed experiment is made to practically measure and extract the slap-induced impact message inside the 6190Z LC diesel engine. Comparison between the simulation and practically measured and reconstructed engine vibration signals verifies the effectiveness and practicality of this approach for more detailed academic research and engineering application.

  14. Investigation of friction characteristics in segmented piston ring liner assembly of IC engine

    Directory of Open Access Journals (Sweden)

    Tejaskumar Chaudhari

    2016-09-01

    Full Text Available The friction at the piston ring cylinder liner assembly (PRLA is a major contributor in the total friction losses in the I.C. engine. New materials, coatings and high-tech machining processes that previously were considered to be too expensive and therefore only used in complex applications are today becoming more affordable. A significant amount of the total power loss in a modern automotive engine is due to the Friction interaction between the top compression ring and the cylinder liner, especially at the TDC and BDC where boundary lubrication exists. The change in piston speed is accompanied with change the lubrication regime in the cylinder, which results change in friction between the ring and the liner during the entire stroke of the piston. Theoretical modelling of friction force from the various sources of friction will be compared to experimental results for analysing the tribological characteristics. The appropriate sample of piston ring and cylinder liner pair is developed for studying the different tribological parameters on Reciprocating Tribometer. The variable parameters are engine speed, oil viscosity, and load. The experimental results and observations are studied under different operating conditions in speed ranges from 300 rpm to 1500 rpm with constant load of 60 N. It can be seen that as speed increases, the friction force and friction coefficient also decreases.

  15. 任意变迹的窄带宽光纤布拉格光栅的制备%Fabrication of arbitrarily apodized fiber Bragg gratings with narrow bandwidth

    Institute of Scientific and Technical Information of China (English)

    吕昌贵; 恽斌峰; 崔一平

    2009-01-01

    A double-exposure fabrication method without any intensity shadow mask to fabricate arbitrarily apodized fiber Bragg gratings(FBGs)with narrow bandwidth is demonstrated by controlling the total ultra violet(UV)irradiation along the graung by varymg the speed of a translation stage.The UV source used is a stable continuous intracavity frequency-doubled argon-ion laser.The parameters(such as length,apodization profle,average index change)of FBGs Can be easily changed with this method.The total UV irradiation is kept constant in the double-exposure process because of the precise control of the exposure time,which ensures that the apodized FBG'S bandwidth can be extremely narrow.Thhe full width at half maximum(FWHM)bandwidth of the 2-cm.long apodized FBG fabricated by this method is 0.15 nm with a maxilnuln reflectivity of more than 95%.%通过控制平台移动速度来控制紫外曝光量和2次曝光的方法实现任意变迹光纤布拉格光栅的制备.该方法采用连续氩离子激光作为紫外光源,不需要光强掩模板,通过对移动平台速度的编程控制可以获得任意的光栅结构参数,如长度、变迹包络、平均折射率改变量等.在2次曝光过程中,由于对2次紫外曝光量的精确控制,整个光栅的总平均折射率变化保持不变,从而避免了由此引起的啁啾而可以获得无旁瓣窄带宽的反射光栅.采用该方法制备了一根2 cm长的高斯变迹光栅,其反射带宽达到了0.15 nm,反射率约为95%.

  16. Scaling laws for free piston Stirling engine design: Benefits and challenges of miniaturization

    International Nuclear Information System (INIS)

    This work explores the scaling effects for FPSE (free piston Stirling engines), which are known for their simple architecture and potentially high thermodynamic performances. Scaling laws are given and their potential for miniaturization is highlighted. A simple model which allows the design of the geometrical parameters of the heat exchangers, the regenerator and the masses of the pistons is proposed. It is based on the definition of six characteristic dimensionless groups. They are derived from the physics underlying the behavior of the free piston Stirling machine and their relevancy is backed up by comparisons between documented Stirling engines from the literature. Keeping constant values for each group throughout the scaling range theoretically ensures constant performance. The main losses of Stirling engine (heat conduction loss, reheat loss in the regenerator, pressure drop and gas-spring hysteresis) can be expressed as a function of the geometrical and operating parameters. Additionally, the consequences of leakage due to the manufacturing precision of pistons architectures are underlined. From the proposed scaling laws, potential power and efficiency of Stirling cycle engines at a millimeter scale can be anticipated. It appears that the power density increases with miniaturization. It is also shown that the dynamic masses related to the engine size are increased when scaling down and that the gap leakage presents the highest detrimental effects on the efficiency. These results call for dedicated architectures for micro-engines. - Highlights: • Similitude strategy is applied to Stirling engines and allows preliminary design. • New scaling laws are derived. • The power density can be increased with miniaturization. • The gap between the piston and casing is highly detrimental to the performances. • High engine operating pressure is required when miniaturizing

  17. Analysis on structural characteristics of rotors in twin-rotor cylinder-embedded piston engine

    Institute of Scientific and Technical Information of China (English)

    陈虎; 潘存云; 徐海军; 邓豪; 韩晨

    2014-01-01

    Twin-rotor cylinder-embedded piston engine is proposed for dealing with the sealing problems of rotors in twin-rotor piston engine where the existent mature sealing technologies for traditional reciprocating engine can be applied. The quantity and forms of its sealing surfaces are reduced and simplified, and what’s more, the advantages of twin-rotor piston engine are inherited, such as high power density and no valve mechanism. Given the motion law of two rotors, its kinematic model is established, and the general expression for some parameters related to engine performance, such as the trajectory, displacement, velocity and acceleration of the piston and centroid trajectory, angular displacement, velocity and acceleration of the rod are presented. By selecting different variation patterns of relative angle of two rotors, the relevant variables are compared. It can be concluded that by designing the relative angle function of two rotors, the volume variation of working chamber can be changed. However, a comprehensive consideration for friction and vibration is necessary because velocity and acceleration are quite different in the different functions, the swing magnitude of rod is proportional to link ratioλ, and the position of rod swing center is controlled by eccentricitye. In order to reduce the lateral force, a smaller value ofλshould be selected in the case of the structure, and the value ofe should be near 0.95. There is no relationship between the piston stroke and the variation process of relative angle of two rotors, the former is only proportional to the amplitude of relative angle of two rotors.

  18. Piston Bowl Optimization for RCCI Combustion in a Light-Duty Multi-Cylinder Engine

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, Reed M [ORNL; Curran, Scott [ORNL; Wagner, Robert M [ORNL; Reitz, Rolf [University of Wisconsin; Kokjohn, Sage [University of Wisconsin, Madison

    2012-01-01

    Reactivity Controlled Compression Ignition (RCCI) is an engine combustion strategy that that produces low NO{sub x} and PM emissions with high thermal efficiency. Previous RCCI research has been investigated in single-cylinder heavy-duty engines. The current study investigates RCCI operation in a light-duty multi-cylinder engine at 3 operating points. These operating points were chosen to cover a range of conditions seen in the US EPA light-duty FTP test. The operating points were chosen by the Ad Hoc working group to simulate operation in the FTP test. The fueling strategy for the engine experiments consisted of in-cylinder fuel blending using port fuel-injection (PFI) of gasoline and early-cycle, direct-injection (DI) of diesel fuel. At these 3 points, the stock engine configuration is compared to operation with both the original equipment manufacturer (OEM) and custom machined pistons designed for RCCI operation. The pistons were designed with assistance from the KIVA 3V computational fluid dynamics (CFD) code. By using a genetic algorithm optimization, in conjunction with KIVA, the piston bowl profile was optimized for dedicated RCCI operation to reduce unburned fuel emissions and piston bowl surface area. By reducing these parameters, the thermal efficiency of the engine was improved while maintaining low NOx and PM emissions. Results show that with the new piston bowl profile and an optimized injection schedule, RCCI brake thermal efficiency was increased from 37%, with the stock EURO IV configuration, to 40% at the 2,600 rev/min, 6.9 bar BMEP condition, and NOx and PM emissions targets were met without the need for exhaust after-treatment.

  19. Rotation of a piston pin in the small connecting rod eye during engine operation; Drehung eines Kolbenbolzens im kleinen Pleuelauge waehrend des Motorbetriebs

    Energy Technology Data Exchange (ETDEWEB)

    Wachtmeister, Georg; Hubert, Andreas [Technische Univ. Muenchen (DE). Lehrstuhl fuer Verbrennungskraftmaschinen (LVK)

    2008-12-15

    A constant increase of powerful combustion engines has lead to higher loads on the crankshaft drive and piston pin. To ensure a robust design the effective forces and movements at the piston pin have to be known. At the Technische Universitaet Muenchen, Chair of Internal Combustion Engines, a research project looked into the piston pins movement during engine operation. The main goal was to determine the rotary movements of the piston pin by measurement at a 4-l gas SI engine as a function of the engine load and speed and to clarify the mechanisms that cause the rotary movement of the piston pin especially in the small connecting rod eye. (orig.)

  20. Error Analysis on Corrector Formula for Rectangular Rule%矩形校正公式的误差分析

    Institute of Scientific and Technical Information of China (English)

    肖泽昌; 杜跃鹏

    2008-01-01

    This paper presents truncation errors among Corrector Formula for left Rectangular rule and Corrector Formula for middle Rectangular rule respectively.It also displays an analysis on convergence order of compound corrector formulas for rectangular rule.Examples of numerical calculation have validated theoretical analysis.

  1. Experimental Study of the Micro-Arc Oxide Coating Effect on Thermal Properties of an Aluminium Alloy Piston Head

    Directory of Open Access Journals (Sweden)

    N.Yu. Dudareva

    2015-09-01

    Full Text Available The purpose of the present study is to investigate the influence of differently sized microarc oxidation coatings, applied to the bottom of pistons made with an Al-12Si-Mg-Cu-Ni alloy, on its thermal properties by simulating the operation of a real engine. This study is based on the premise that the alumina coating thickness affects the heat transfer and temperature distribution in the piston. The analysis of thermal properties of pistons and suggestions for the optimal thermal barrier coating thickness are presented.

  2. Modelling of ultrasonic nondestructive testing in anisotropic materials - Rectangular crack

    International Nuclear Information System (INIS)

    Nondestructive testing with ultrasound is a standard procedure in the nuclear power industry when searching for defects, in particular cracks. To develop and qualify testing procedures extensive experimental work on test blocks is usually required. This can take a lot of time and therefore be quite costly. A good mathematical model of the testing situation is therefore of great value as it can reduce the experimental work to a great extent. A good model can be very useful for parametric studies and as a pedagogical tool. A further use of a model is as a tool in the qualification of personnel. In anisotropic materials, e.g. austenitic welds, the propagation of ultrasound becomes much more complicated as compared to isotropic materials. Therefore, modelling is even more useful for anisotropic materials, and it in particular has a greater pedagogical value. The present project has been concerned with a further development of the anisotropic capabilities of the computer program UTDefect, which has so far only contained a strip-like crack as the single defect type for anisotropic materials. To be more specific, the scattering by a rectangular crack in an anisotropic component has been studied and the result is adapted to include transmitting and receiving ultrasonic probes. The component under study is assumed to be anisotropic with arbitrary anisotropy. On the other hand, it is assumed to be homogeneous, and this in particular excludes most welds, where it is seldom an adequate approximation to assume homogeneity. The anisotropy may be arbitrarily oriented and the same is true of the rectangular crack. The crack may also be located near a backside of the component. To solve the scattering problem for the crack an integral equation method is used. The probe model has been developed in an earlier project and to compute the signal response in the receiving probe an electromechanical reciprocity argument is employed. As a rectangle is a truly 3D scatterer the sizes of the

  3. Numerical Simulation of Bragg Reflection Based on Linear Waves Propagation over A Series of Rectangular Seabed

    Institute of Scientific and Technical Information of China (English)

    Chih-Chung WEN; Li-Hung TSAI

    2008-01-01

    A numerical model, Evolution Equation of Mild-Slope Equation (EEMSE) developed by Hsu et al. (2003), was applied to study the Bragg reflection of water waves over a series of rectangular seabed. Three key parameters of the Bragg reflection including the peak coefficient of primary Bragg reflection, its corresponding relative wavelength, and the bandwidth, have shown to be effective in describing the characteristics of the primary Bragg reflection. The characteristics of the Bragg reflection were investigated under the various conditions comprising number, height, and spacing interval of a series of rectangular seabed. The results reveal that the peak of Bragg reflection increases with the increase of rectangular seabed height and number, the bandwidth and the shift value of the Bragg reflection depend on the increase of the rectangular seabed height as well as the decrease of rectangular seabed number, and the relative rectangular seabed spacing in the rang of 3 and 4 could produce higher Bragg reflection. Finally, a correlative and regressive analysis is performed by use of the calculated data. Based on the results of the analysis, empirical equations were established. Our study results can provide an appropriate choice of a series of rectangular seabed field for a practical design.

  4. Tapered Simplified Modal Method for Analysis of Non-rectangular Gratings

    CERN Document Server

    Li, Shuai; Barbastathis, George

    2016-01-01

    The Simplified Modal Method (SMM) provides a quick and intuitive way to analyze the performance of gratings of rectangular shapes. For non-rectangular shapes, a version of SMM has been developed, but it applies only to the Littrow-mounting incidence case and it neglects reflection. Here, we use the theory of mode-coupling in a tapered waveguide to improve SMM so that it applies to non-rectangular gratings at arbitrary angles of incidence. Moreover, this new 'Tapered Simplified Modal Method' (TSMM) allows us to properly account for reflected light. We present here the analytical development of the theory and numerical simulations, demonstrating the validity of the method.

  5. The study, design and simulation of a free piston Stirling engine linear alternatorThe study, design and simulation of a free piston Stirling engine linear alternator

    Directory of Open Access Journals (Sweden)

    Teodora Susana Oros

    2014-12-01

    Full Text Available This paper presents a study, design and simulation of a Free Piston Stirling Engine Linear Alternator. There are presented the main steps of the magnetic and electric calculations for a permanent magnet linear alternator of fixed coil and moving magnets type. Finally, a detailed thermal, mechanical and electrical model for a Stirling engine linear alternator have been made in SIMULINK simulation program. The linear alternator simulation model uses a controllable DC voltage which simulates the linear alternator combined with a rectifier, a variable load and a DC-DC converter, which compensates for the variable nature of Stirling engine operation, and ensures a constant voltage output regardless of the load.

  6. Diversity of acoustic streaming in a rectangular acoustofluidic field.

    Science.gov (United States)

    Tang, Qiang; Hu, Junhui

    2015-04-01

    Diversity of acoustic streaming field in a 2D rectangular chamber with a traveling wave and using water as the acoustic medium is numerically investigated by the finite element method. It is found that the working frequency, the vibration excitation source length, and the distance and phase difference between two separated symmetric vibration excitation sources can cause the diversity in the acoustic streaming pattern. It is also found that a small object in the acoustic field results in an additional eddy, and affects the eddy size in the acoustic streaming field. In addition, the computation results show that with an increase of the acoustic medium's temperature, the speed of the main acoustic streaming decreases first and then increases, and the angular velocity of the corner eddies increases monotonously, which can be clearly explained by the change of the acoustic dissipation factor and shearing viscosity of the acoustic medium with temperature. Commercialized FEM software COMSOL Multiphysics is used to implement the computation tasks, which makes our method very easy to use. And the computation method is partially verified by an established analytical solution.

  7. The refined theory of deep rectangular beams for symmetrical deformation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Based on elasticity theory, various one-dimensional equations for symmetrical deformation have been deduced systematically and directly from the two-dimensional theory of deep rectangular beams by using the Papkovich-Neuber solution and the Lur’e method without ad hoc assumptions, and they construct the refined theory of beams for symmetrical deformation. It is shown that the displacements and stresses of the beam can be represented by the transverse normal strain and displacement of the mid-plane. In the case of homogeneous boundary conditions, the exact solutions for the beam are derived, and the exact equations consist of two governing differential equations: the second-order equation and the transcendental equation. In the case of non-homogeneous boundary conditions, the approximate governing differential equations and solutions for the beam under normal loadings only and shear loadings only are derived directly from the refined beam theory, respectively, and the correctness of the stress assumptions in classic extension or compression problems is revised. Meanwhile, as an example, explicit expressions of analytical solutions are obtained for beams subjected to an exponentially distributed load along the length of beams.

  8. Vibration Analysis of Composite Rectangular Plates Reinforced along Curved Lines

    Science.gov (United States)

    Honda, Shinya; Oonishi, Yoshimasa; Narita, Yoshihiro; Sasaki, Katsuhiko

    In the past few decades, composite materials composed of straight fibers and polymer matrix have gained their status as the most promising material for light-weight structures. Technical merit of the composites as tailored material also provided practical advantages in the optimum design process. Recently, it is reported that the fabrication machine has been developed to make curved fibers embedded in the matrix material. Based on such technical advancement, this paper proposes an analytical method to study vibration of composite rectangular plates reinforced along curved lines. The approach is based on the Ritz method where variable fiber direction can be accommodated. For this purpose, the fibers continuously changing their direction are formulated as the variable bending stiffness in the total potential energy. A frequency equation is derived by the Ritz minimizing process, and frequency parameters are calculated as the eigenvlaues in the eigenvalue problem. In numerical results, the accuracy of the method is presented by comparing present results with FEM results. The advantages of present plate are confirmed by comparing natural frequencies and mode shapes with those of conventional composite and isotropic plates, and the effectiveness of the new solution to the most recent problem is demonstrated.

  9. Attenuation in Rectangular Waveguides with Finite Conductivity Walls

    Directory of Open Access Journals (Sweden)

    K. C. Yeong

    2011-06-01

    Full Text Available We present a fundamental and accurate approach to compute the attenuation of electromagnetic waves propagating in rectangular waveguides with finite conductivity walls. The wavenumbers kx and ky in the x and y directions respectively, are obtained as roots of a set of transcendental equations derived by matching the tangential component of the electric field (E and the magnetic field (H at the surface of the waveguide walls. The electrical properties of the wall material are determined by the complex permittivity ε, permeability μ, and conductivity σ. We have examined the validity of our model by carrying out measurements on the loss arising from the fundamental TE10 mode near the cutoff frequency. We also found good agreement between our results and those obtained by others including Papadopoulos’ perturbation method across a wide range of frequencies, in particular in the vicinity of cutoff. In the presence of degenerate modes however, our method gives higher losses, which we attribute to the coupling between modes as a result of dispersion.

  10. Laminar flow of micropolar fluid in rectangular microchannels

    Institute of Scientific and Technical Information of China (English)

    Shangjun Ye; Keqin Zhu; Wen Wang

    2006-01-01

    Compared with the classic flow on macroscale, flows in microchannels have some new phenomena such as the friction increase and the flow rate reduction. Papautsky and co-workers explained these phenomena by using a micropolar fluid model where the effects of micro-rotation of fluid molecules were taken into account. But both the curl of velocity vector and the curl of micro-rotation gyration vector were given incorrectly in the Cartesian coordinates and then the micro-rotation gyration vector had only one component in the (z)-direction. Besides, the gradient term of the divergence of micro-rotation gyration vector was missed improperly in the angular moment equation. In this paper. the governing equations for laminar flows of micropolar fluid in rectangular microchannels are reconstructed. The numerical results of velocity profiles and micro-rotation gyrations are obtained by a procedure based on the Chebyshev collocation method. The micropolar effects on velocity and micro-rotation gyration are discussed in detail.

  11. Flux characteristics of cell culture medium in rectangular microchannels.

    Science.gov (United States)

    Feng, Zhonggang; Fukuda, Shuhei; Yokoyama, Michio; Kitajima, Tatsuo; Nakamura, Takao; Umezu, Mitsuo

    2011-09-01

    Rectangular microchannels 50 μm high and 30, 40, 50, 60, or 70 μm wide were fabricated by adjusting the width of a gap cut in a polyethylene sheet 50 μm thick and sandwiching the sheet between an acrylic plate and a glass plate. Flux in the microchannels was measured under three different inner surface conditions: uncoated, albumin-coated, and confluent growth of rat fibroblasts on the bottom of the microchannels. The normalized flux in microchannels with cultured fibroblasts or albumin coating was significantly larger than that in the uncoated channels. The experimental data for all microchannels deviated from that predicted by classical hydrodynamic theory. At small aspect ratio the flux in the microchannels was larger than that predicted theoretically, whereas it became smaller at large aspect ratio. The aspect ratio rather than Reynolds number is the correct property for predicting the variation of the normalized friction factor. We postulate that two counteracting effects, rotation of large molecules and slip velocity at the corners of the microchannels, are responsible for the deviation. From these results we conclude that albumin coating should be carried out in the same way as when fabricating our integrating cell-culture system. The outcomes of this study are not only important for the design of our culture system, but also quite informative for general microfluidics.

  12. LEDA 074886: A remarkable rectangular-looking galaxy

    CERN Document Server

    Graham, Alister W; Forbes, Duncan A; Lisker, Thorsten; Moore, Ben; Janz, Joachim

    2012-01-01

    We report the discovery of an interesting and rare, rectangular-shaped galaxy. At a distance of 21 Mpc, the dwarf galaxy LEDA 074886 has an absolute R-band magnitude of -17.3 mag. Adding to this galaxy's intrigue is the presence of an embedded, edge-on stellar disk (of extent 2R_{e,disk} = 12 arcsec = 1.2 kpc) for which Forbes et al. reported V_rot/sigma ~ 1.4. We speculate that this galaxy may be the remnant of two (nearly edge-one) merged disk galaxies in which the initial gas was driven inward and subsequently formed the inner disk, while the stars at larger radii effectively experienced a dissipationless merger event resulting in this `emerald cut galaxy' having very boxy isophotes with a_4/a = -0.05 to -0.08 from 3 to 5 kpc. This galaxy suggests that knowledge from simulations of both `wet' and `dry' galaxy mergers may need to be combined to properly understand the various paths that galaxy evolution can take, with a particular relevance to blue elliptical galaxies.

  13. Deformation of rectangular thin glass plate coated with magnetostrictive material

    Science.gov (United States)

    Wang, Xiaoli; Yao, Youwei; Liu, Tianchen; Liu, Chian; Ulmer, M. P.; Cao, Jian

    2016-08-01

    As magnetic smart materials (MSMs), magnetostrictive materials have great potential to be selected as coating materials for lightweight x-ray telescope mirrors due to their capability to tune the mirror profile to the desired shape under a magnetic field. To realize this potential, it is necessary to study the deformation of the mirror substrate with the MSM coating subjected to a localized magnetic field. In this paper, an analytical model is developed to calculate the deformation of rectangular coated samples locally affected by magnetostrictive strains driven by an external magnetic field. As a specific case to validate the model, a square glass sample coated with MSMs is prepared, and its deformation is measured in a designed experimental setup by applying a magnetic field. The measured deformation of the sample is compared with the results calculated from the analytical model. The comparison results demonstrate that the analytical model is effective in calculating the deformation of a coated sample with the localized mismatch strains between the film and the substrate. In the experiments, different shape patterns of surface profile changes are achieved by varying the direction of the magnetic field. The analytical model and the experimental method proposed in this paper can be utilized to further guide the application of magnetostrictive coating to deformable lightweight x-ray mirrors in the future.

  14. Diffraction of surface wave on conducting rectangular wedge

    CERN Document Server

    Kotelnikov, Igor A; Knyazev, Boris A

    2013-01-01

    Diffraction of a surface wave on a rectangular wedge with impedance faces is studied using the Sommerfeld-Malyuzhinets technique. An analog of Landau's bypass rule in the theory of plasma waves is introduced for selection of a correct branch of the Sommerfeld integral, and the exact solution is given in terms of imaginary error function. The formula derived is valid both in the near-field and far-wave zones. It is shown that a diffracted surface wave is completely scattered into freely propagating electromagnetic waves and neither reflected nor transmitted surface waves are generated in case of bare metals which have positive real part of surface impedance. The scattered waves propagate predominantly at a grazing angle along the direction of propagation of the incident surface wave and mainly in the upper hemisphere regarding the wedge face. The profile of radiated intensity is nonmonotonic and does not resemble the surface wave profile which exponentially evanesces with the distance from the wedge face. Comp...

  15. Mixing of two different electrolyte solutions in electromagnetic rectangular mixers

    Institute of Scientific and Technical Information of China (English)

    Meimei WEN; Chang Nyung KIM; Yue YAN

    2016-01-01

    This study proposes a new electromagnetic rectangular mixer, and numerically examines the mixing characteristics of two different electrolyte solutions in the device under a uniform magnetic field. The mixer consists of a conduit with electrodes equipped on its top and bottom walls. The difference in the electric potentials applied to the sets of electrodes induces the current. The combi- nation of the induced current and magnetic field yields Lorentz force, resulting in the fluid motion for pumping and mixing of the two different fluids. The numerical simulation is carried out with the use of commercial software CFX. The present numerical model is validated by an existing numerical work. The effect of different variables on mixing efficiency is investigated in many different cases with two different heights of the duct and various input voltages of the electrodes. The current simulation results indicate that the mixing performance can be enhanced by using multiple sets of electrodes and applying higher input voltages (absolute values) to the electrodes.

  16. Metamaterial absorbers realized in an X-band rectangular waveguide

    Institute of Scientific and Technical Information of China (English)

    Huang Yong-Jun; Wen Guang-Jun; Li Jian; Zhong Jing-Ping; Wang Ping; Sun Yuan-Hua; O.Gordon; Zhu Wei-Ren

    2012-01-01

    In this paper,we demonstrate six types of metamaterial absorbers (MMAs) by measuring their absorptivities in an X-band (8-12 GHz) rectangular waveguide.Some of the MMAs have been demonstrated previously by using the free space measurement method,and the others are proposed firstly in this paper.The measured results show that all of the six MMAs exhibit high absorptivities above 98%,which have similar absorbing characteristics to those measured in the free space.The numerically obtained surface current densities for each MMA show that the absorbing mechanism is the same as that under the free space conditions.Such a demonstration method is superior to the conventional free space measurement method due to the small-scale test samples required,the simple measure device,and its low cost.Most importantly,the proposed method opens a way to enable MMAs to be used in microwave applications such as matched terminations.

  17. Formation of hydrate plug within rectangular natural gas passage

    Energy Technology Data Exchange (ETDEWEB)

    Seong, K.; Song, M.H.; Ahn, J.H.; Yoo, K.S. [Dong Guk Univ., Joong-ku, Seoul (Korea, Republic of)

    2008-07-01

    Oil and gas reservoirs in off-shore shallow areas are being depleted. At the same time, the industry is expanding its production sites into deeper waters resulting in higher pressure and lower temperature and more isolated locations. In response, connecting pipelines have been extended, but because of these pressure, temperature and distance changes in pipelines, a more favorable condition for hydrate formation is created, making the problem of flow assurance more critical for safe and economic operations at deep off-shore oil and gas production sites. Another challenge in flow assurance lies in hydrate formation and potential blockage due to hydrate plugs in gas pipelines, where no free water phase is present. This paper presented an experimental study that examined the formation and the growth of hydrates from a gas mixture of methane and propane with different moisture concentrations. The hydrates were formed in a rectangular passage cooled to temperatures below equilibrium hydrate formation temperature. The paper described the experimental procedure and apparatus that was designed and fabricated for the study. A schematic layout of the hydrate formation and plug test experimental apparatus was illustrated. The paper also described the results of two sets of experiments that were conducted. It was concluded that with enough moisture content, hydrates formed without a fresh water phase under equilibrium conditions. It was also concluded that the results of the study could be used in verifying numerical models developed to predict hydrate plugging of natural gas pipelines. 4 refs., 6 figs.

  18. Pool boiling on rectangular fins with tunnel-pore structure

    Directory of Open Access Journals (Sweden)

    Pastuszko A.

    2013-04-01

    Full Text Available Complex experimental investigations were conducted in the area of pool boiling heat transfer on extended surfaces with internal tunnels limited by perforated foil. The experiments were carried out for water and R-123 at atmospheric pressure. The tunnel surfaces were fabricated from 0.05 – 0.1 mm thick perforated copper foil (pore diameters: 0.3, 0.4, 0.5 mm sintered with mini-fins formed by 5 and 10 mm high rectangular fins and horizontal inter-fin surface. The effect of the main fin height, pore diameters and tunnel pitch on nucleate pool boiling was examined. Substantial enhancement of heat transfer coefficient was observed for the investigated surfaces. The highest increase in the heat transfer coefficient was obtained for the 10 mm high fins – about 50kW/m2K for water and 15 kW/m2K for R-123. The investigated surfaces showed boiling heat transfer coefficients similar to those of existing tunnel-pore structures.

  19. Capillary driven flow of polydimethylsiloxane in open rectangular microchannels.

    Science.gov (United States)

    Sowers, Timothy W; Sarkar, Rohit; Eswarappa Prameela, Suhas; Izadi, Ehsan; Rajagopalan, Jagannathan

    2016-06-29

    The flow of liquid polydimethylsiloxane (PDMS, Dow Corning Sylgard 184, 10 : 1 base to cross-linker ratio) in open, rectangular silicon microchannels, with and without a coating (100 nm) of poly-tetra-fluoro-ethylene (PTFE), was studied. Photolithographic patterning and etching of silicon wafers was used to create microchannels with a range of widths (∼5-50 μm) and depths (5-20 μm). Experimental PDMS flow rates in both PTFE-coated and uncoated channels were compared to an analytical model based on the work of Lucas and Washburn. The experimental flow rates matched the predicted flow rates reasonably well when the channel aspect ratio (width to depth), p, was less than 2. For channels with p > 2, the observed flow rates progressively lagged model predictions with increasing p. The experimental data, including zero flow rates in certain high aspect ratio PTFE-coated channels, can largely be explained by changes in the front and upper meniscus morphology of the flow as the channel aspect ratio is varied. The results strongly suggest that meniscus morphology needs to be taken into account to accurately model capillary flow in microchannels, especially those with large aspect ratios.

  20. Efficient computation of coherent synchrotron radiation in a rectangular chamber

    Science.gov (United States)

    Warnock, Robert L.; Bizzozero, David A.

    2016-09-01

    We study coherent synchrotron radiation (CSR) in a perfectly conducting vacuum chamber of rectangular cross section, in a formalism allowing an arbitrary sequence of bends and straight sections. We apply the paraxial method in the frequency domain, with a Fourier development in the vertical coordinate but with no other mode expansions. A line charge source is handled numerically by a new method that rids the equations of singularities through a change of dependent variable. The resulting algorithm is fast compared to earlier methods, works for short bunches with complicated structure, and yields all six field components at any space-time point. As an example we compute the tangential magnetic field at the walls. From that one can make a perturbative treatment of the Poynting flux to estimate the energy deposited in resistive walls. The calculation was motivated by a design issue for LCLS-II, the question of how much wall heating from CSR occurs in the last bend of a bunch compressor and the following straight section. Working with a realistic longitudinal bunch form of r.m.s. length 10.4 μ m and a charge of 100 pC we conclude that the radiated power is quite small (28 W at a 1 MHz repetition rate), and all radiated energy is absorbed in the walls within 7 m along the straight section.

  1. A seasonal Bartlett-Lewis Rectangular Pulse model

    Science.gov (United States)

    Ritschel, Christoph; Agbéko Kpogo-Nuwoklo, Komlan; Rust, Henning; Ulbrich, Uwe; Névir, Peter

    2016-04-01

    Precipitation time series with a high temporal resolution are needed as input for several hydrological applications, e.g. river runoff or sewer system models. As adequate observational data sets are often not available, simulated precipitation series come to use. Poisson-cluster models are commonly applied to generate these series. It has been shown that this class of stochastic precipitation models is able to well reproduce important characteristics of observed rainfall. For the gauge based case study presented here, the Bartlett-Lewis rectangular pulse model (BLRPM) has been chosen. As it has been shown that certain model parameters vary with season in a midlatitude moderate climate due to different rainfall mechanisms dominating in winter and summer, model parameters are typically estimated separately for individual seasons or individual months. Here, we suggest a simultaneous parameter estimation for the whole year under the assumption that seasonal variation of parameters can be described with harmonic functions. We use an observational precipitation series from Berlin with a high temporal resolution to exemplify the approach. We estimate BLRPM parameters with and without this seasonal extention and compare the results in terms of model performance and robustness of the estimation.

  2. Granular segregation in quasi-2d rectangular bin

    Science.gov (United States)

    Gharat, Sandip H.; Khakhar, D. V.

    2013-06-01

    Experiments are carried out in quasi two-dimensional rectangular bin (two vertical glass plate separated by a gap of 10 mm) to study the effect of feed composition on segregation of granular mixtures during heap formation by intermittent feeding. The stainless steel (SS 316) balls of different sizes (1 and 2 mm) are used as model granular materials. The heap is formed by repeatedly pouring a fixed mass of the mixture. Each feeding results in the formation of a layer of the mixture on the surface of the heap. Results presented here are for binary mixtures with different size and equal density. Profiles of the number fraction of big particles along the flow direction averaged across the depth of the layer are plotted. In each layer formed by a pouring, segregation results in the small particles being deposited first. Thus, the small particles are concentrated in the upper part of the layer and the large particles in the lower part with a mixed region between the two. The extent of segregation is found to increase with decrease in concentration of big particles in the mixture.

  3. Calibration and comparison of the NASA Lewis free-piston Stirling engine model predictions with RE-1000 test data

    Science.gov (United States)

    Geng, Steven M.

    1987-01-01

    A free-piston Stirling engine performance code is being upgraded and validated at the NASA Lewis Research Center under an interagency agreement between the Department of Energy's Oak Ridge National Laboratory and NASA Lewis. Many modifications were made to the free-piston code in an attempt to decrease the calibration effort. A procedure was developed that made the code calibration process more systematic. Engine-specific calibration parameters are often used to bring predictions and experimental data into better agreement. The code was calibrated to a matrix of six experimental data points. Predictions of the calibrated free-piston code are compared with RE-1000 free-piston Stirling engine sensitivity test data taken at NASA Lewis. Resonable agreement was obtained between the code predictions and the experimental data over a wide range of engine operating conditions.

  4. An Experimental Investigation on the Combustion and Heat Release Characteristics of an Opposed-Piston Folded-Cranktrain Diesel Engine

    Directory of Open Access Journals (Sweden)

    Fukang Ma

    2015-06-01

    Full Text Available In opposed-piston folded-cranktrain diesel engines, the relative movement rules of opposed-pistons, combustion chamber components and injector position are different from those of conventional diesel engines. The combustion and heat release characteristics of an opposed-piston folded-cranktrain diesel engine under different operating conditions were investigated. Four phases: ignition delay, premixed combustion, diffusion combustion and after combustion are used to describe the heat release process of the engine. Load changing has a small effect on premixed combustion duration while it influences diffusion combustion duration significantly. The heat release process has more significant isochoric and isobaric combustion which differs from the conventional diesel engine situation, except at high exhaust pressure and temperature, due to its two-stroke and uniflow scavenging characteristics. Meanwhile, a relatively high-quality exhaust heat energy is produced in opposed-piston folded-cranktrain diesel engines.

  5. development of a Free-Piston Linear Generator for use in an Extended-Range Electric Vehicle

    OpenAIRE

    Ferrari, Cornelius; Friedrich, Horst E.

    2012-01-01

    This paper presents the development methodology of the Free-Piston Linear Generator. The FPLG is a free-piston combustion engine with an integrated linear generator. The engine can be used as a range-extending device in an electric vehicle. A systematic development approach for the FPLG is presented consisting of three basic steps. The fully variable experimental apparatus being used for testing the single FPLG-subsystems and the FPLG-system is described. In order to achieve robust operation ...

  6. Ultrasonic Imaging of the Piston Ring Oil Film during operation in a Motored Engine – Towards Oil Film Measurement

    OpenAIRE

    Avan, E.Y.; Mills, R.S.; Dwyer-Joyce, R.S.

    2010-01-01

    The oil film that forms between piston rings and cylinder liners is an essential parameter which influences parasitic loss and emission rates in an internal combustion (IC) engine. Several methods have been used to analyse these thin oil films in the past, however, all these methods have required invasive access to the contact area via a window or a surface mounted sensor in the cylinder wall or liner. This paper introduces a novel approach for the imaging of the piston ring - cylinder contac...

  7. Performance analysis and field testing of a compact dual-piston, hydraulic sucker rod pumping unit

    Energy Technology Data Exchange (ETDEWEB)

    Evans, R.D.; Weaver, P.

    1985-03-01

    This paper presents a new compact dual acting piston hydraulic sucker rod pumping unit. Some unique advantages of the unit are presented. Stroke length and speed are readily changed by simple adjustments made to the hydraulics. Larger hydraulic piston cylinders are interchangable without having to replace the entire unit. Performance data is presented which compares the hydraulic unit against selected conventional rotary pumping units. A comparison is made between the hydraulic unit and conventional beam pumping units. Performance evaluations were made, based on numerous accoustical well sounding and dynamometer tests. Field dynagraph cards and their analysis are presented which provide a quantitative comparison of the hydraulic unit versus the beam unit. The results obtained verify that the hydraulic unit is superior to that of a conventional well pumping unit. Economic advantages and potential applications of the hydraulic unit are discussed.

  8. Demonstration of a free piston Stirling engine driven linear alternator system. Annual report

    International Nuclear Information System (INIS)

    The objective of the program is to develop a 2 kW Free Piston Stirling Engine/Linear Alternator Energy Conversion System for an isotopic heat source with a greater than 30% overall efficiency. The work was broken up into two phases. Phase I demonstrated the feasibility of the energy conversion system through analysis and experimental testing of the individual components. Phase II is a two-year effort to design, fabricate, and test a prototype demonstrator energy conversion system. The reprt documents the work performed during October 1976 through September 1977, the first year of Phase II. Details of the tasks are presented in five major sections: (1) Linear Alternator Development; (2) Engine/Alternator System Demonstration; (3) Demonstrator Preliminary Design; (4) Demonstrator Detailed Design; and (5) Development of Free Piston Stirling Engine Computer Simulation

  9. Sparse aperture differential piston measurements using the pyramid wave-front sensor

    CERN Document Server

    Arcidiacono, Carmelo; Yan, Zhaojun; Zheng, Lixin; Agapito, Guido; Wang, Chaoyan; Zhu, Nenghong; Zhu, Liyun; Cai, Jianqing; Tang, Zhenghong

    2016-01-01

    In this paper we report on the laboratory experiment we settled in the Shanghai Astronomical Observatory (SHAO) to investigate the pyramid wavefront sensor (WFS) ability to measure the differential piston on a sparse aperture. The ultimate goal is to verify the ability of the pyramid WFS work in closed loop to perform the phasing of the primary mirrors of a sparse Fizeau imaging telescope. In the experiment we installed on the optical bench we performed various test checking the ability to flat the wave-front using a deformable mirror and to measure the signal of the differential piston on a two pupils setup. These steps represent the background from which we start to perform full closed loop operation on multiple apertures. These steps were also useful to characterize the achromatic double pyramids (double prisms) manufactured in the SHAO optical workshop.

  10. Experimental Research for Measuring Friction Forces from Piston Sealing at the Hydraulic Cylinders

    Directory of Open Access Journals (Sweden)

    C. Cristescu

    2014-12-01

    Full Text Available The article presents some aspects of developing, within INOE 2000-IHP, of an experimental research on the determination of frictional forces that occur in the mobile sealings of the pistons, between the piston sealings and the inner liner of hydraulic cylinders. In the first part of the paper, are presented some specific elements of the experimental device and of the testing stand which have been developed, while in the second part are presented some graphical results obtained in experimental research, as well as some comments on them. This developed experimental research marks the continuing of a major action on the tribological behavior of mobile hydraulic seals, which are frequently used in the construction of hydraulic cylinders.

  11. Numerical Simulation of a Spark Ignited Two-Stroke Free-Piston Engine Generator

    Institute of Scientific and Technical Information of China (English)

    MAO Jin-long; ZUO Zheng-xing; LIU Dong

    2009-01-01

    A numerical program is built to simulate the performance of a spark ignited two-stroke free-piston engine coupled with a linear generator. The computational model combines a series of dynamic and thermodynamic equations that are solved simultaneously to predict the performances of the engines. The dynamic analysis performed consists of an evaluation of the frictional force and load force introduced by the generator. The thermodynamic analysis used a single zone model to describe the engine's working cycle which includes intake, scavenging, compression, combustion and expansion, and to evaluate the effect of heat transfer based on the first law of thermodynamics and the ideal gas state equation. Because there is no crankshaft, a time based Wiebe equation was used to express the fraction of fuel burned in the combustion. The calculated results were validated by using the experimental data from another research group. The results indicate that the free-piston generator has some advantages over conventional engines.

  12. Casimir Force of Piston Systems with Arbitrary Cross Sections under Different Boundary Conditions

    Institute of Scientific and Technical Information of China (English)

    XIONG Ai-Min; CHEN Xiao-Song

    2009-01-01

    We study the Casimir force between two pistons under different boundary conditions inside an infinite cylinder with arbitrary cross section.It is found that the attractive or repulsive character of the Casimir force for a scalar field is determined only by the boundary condition along the longitudinal direction and is independent of the cross section,transverse boundary conditions and the mass of the field.Under symmetric Dirichlet-Dirichlet,Neumann-Neumann and periodic longitudinal boundary conditions the Casimir force is always attractive,but is repulsive under non-symmetric Dirichlet-Neumann and anti-periodic longitudinal boundary conditions.The Casimir force of the electromagnetic field in an ideal conductive piston is also investigated.This force is always attractive regardless of the shape of the cross section and the transverse boundary conditions.

  13. The intermetallic bonding between a ring carrier and aluminum piston alloy

    Energy Technology Data Exchange (ETDEWEB)

    Manasijevie, S.; Dolie, N.; Djurdjevic, M.; Misic, N.; Davitkov, N.

    2015-07-01

    This paper presents the results of investigating the formation of intermetallic bond between a ring carrier and aluminum piston alloy. The ring carrier is made of austenitic cast iron (Ni-Resist) in order to increase the wear resistance of the first ring groove and applied in highly loaded diesel engines. Metallographic examination of the quality of al fin bond was done. A metallographic investigation using an optical microscope in combination with the SEM/EDS analysis of the quality of the intermetallic bonding layer was done. The test results show that can be made successfully as well as the formation of metal connection (alfin bond) between the ring carrier and aluminum piston alloy. (Author)

  14. Electrothermally actuated tip-tilt-piston micromirror with integrated varifocal capability.

    Science.gov (United States)

    Morrison, Jessica; Imboden, Matthias; Little, Thomas D C; Bishop, D J

    2015-04-01

    MEMS micromirrors have proven to be very important optical devices with applications ranging from steerable mirrors for switches and cross-connects to spatial light modulators for correcting optical distortions. Usually beam steering and focusing are done with different MEMS devices and tilt angles in excess of 10 degrees are seldom obtained. Here we describe a single MEMS device that combines tip/tilt, piston mode and varifocal capability into a single, low cost device with very large tilt angles. Our device consists of a 400 micron diameter mirror driven with thermal bimorphs. We have demonstrated deflection angles of ± 40 degrees along both axes, a tunable focal length which varies between -0.48 mm to + 20.5 mm and a piston mode range of 300 microns - four separately controllable degrees of freedom in a single device. Potential applications range from smart lighting to optical switches and devices for telecom systems. PMID:25968784

  15. Design & Development of a High Mass Flow Piston Synthetic Jet Actuator

    Science.gov (United States)

    Ashraf, Hamad Muhammad; Murugan Illikkal, Karthika; D'souza, Francis; Alsayed Mahmood, Mohamed; Mahmud Mostafa, Suhail; Kim, Young Hwan

    2015-05-01

    The idea of having a device that is capable of working in a systematic process allowing control of the boundary layer by means of operated on high-frequency, small-scale, and low energy actuators has caught the interest of the aerodynamicist community. With an eye on the available data and potential flow control advantages, our research team set out to manufacture a compact SJA (Synthetic Jet Actuator) of its own, which would be capable of being installed inside an airfoil. It consists of components such as a single piston cylinder, with variable exit geometry along with the control system that has an electrical actuator which can be regulated in order for it to be capable of producing various operating frequencies. This paper consists of a study into the design of a single piston device SJA and will present all significant data both theoretical and computational regarding its design and performance.

  16. Design & Development of a High Mass Flow Piston Synthetic Jet Actuator

    Directory of Open Access Journals (Sweden)

    Ashraf Hamad Muhammad

    2015-01-01

    Full Text Available The idea of having a device that is capable of working in a systematic process allowing control of the boundary layer by means of operated on high-frequency, small-scale, and low energy actuators has caught the interest of the aerodynamicist community. With an eye on the available data and potential flow control advantages, our research team set out to manufacture a compact SJA (Synthetic Jet Actuator of its own, which would be capable of being installed inside an airfoil. It consists of components such as a single piston cylinder, with variable exit geometry along with the control system that has an electrical actuator which can be regulated in order for it to be capable of producing various operating frequencies. This paper consists of a study into the design of a single piston device SJA and will present all significant data both theoretical and computational regarding its design and performance.

  17. Blind source separation of internal combustion engine piston slap from other measured vibration signals

    Science.gov (United States)

    Liu, Xianhua; Randall, R. B.

    2005-11-01

    Internal combustion engines have several vibration sources, such as combustion, fuel injection, piston slap and valve operation. For machine condition monitoring or design improvement purposes, it is necessary to separate the vibration signals caused by different sources and then analyse each of them individually. However, traditional frequency analysis techniques are not very useful due to overlap of the different sources over a wide frequency range. This paper attempts to separate the vibration sources, especially piston slap, by using blind source separation techniques with the intention of revealing the potential of the new technique for solving mechanical vibration problems. The BSS method and the Blind least mean square algorithm using Gray's variable norm as a measure of non-Gaussianity of the sources is briefly described and separation results for both simulated and measured data are presented and discussed.

  18. Irregular C2 surface construction using bi-polynomial rectangular patches

    OpenAIRE

    Gregory, JA; Zhou, J.

    1991-01-01

    The construction of C2 surfaces using bi-polynomial parametric rectangular patches is studied. In particular, the analy- sis of the C2 continuity conditions for the case of n patches meeting at an n-vertex is developed.

  19. ADAPTIVE RECONSTRUCTION TECHNIQUE FOR THE LOST INFORMATION OF THE RECTANGULAR IMAGE AREA

    Institute of Scientific and Technical Information of China (English)

    Shi Rong; Li Xiaofeng; Li Zaiming

    2004-01-01

    The adaptive reconstruction for the lost information of the rectangular image area is very important for the robust transmission and restoration of the image. In this paper, a new reconstruction method based on the Discrete Cosine Transform (DCT) domain has been put forward. According to the low pass character of the human visual system and the energy distribution of the DCT coefficients on the rectangular boundary, the DCT coefficients of the rectangular image area are adaptively selected and recovered. After the Inverse Discrete Cosine Transform (IDCT), the lost information of the rectangular image area can be reconstructed. The experiments have demonstrated that the subjective and objective qualities of the reconstructed images are enhanced greatly than before.

  20. Hubbell rectangular source integral calculation using a fast Chebyshev wavelets method.

    Science.gov (United States)

    Manai, K; Belkadhi, K

    2016-07-01

    An integration method based on Chebyshev wavelets is presented and used to calculate the Hubbell rectangular source integral. A study of the convergence and the accuracy of the method was carried out by comparing it to previous studies. PMID:27152913

  1. Simulation of natural circulation in a rectangular loop using CFD code PHOENICS

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M.; Borghain, A.; Maheshwari, N.K.; Vijayan, P.K. [Bhabha Atomic Reseach Centre, Trombay, Mumbai (India). Reactor Engineering Div.

    2011-05-15

    Single phase natural circulation in a rectangular loop is simulated using the PHOENICS code, a general purpose Computational Fluid Dynamics (CFD) code. The rectangular loop, having different operating power levels, has been modeled with the help of the Multiple Block Fine Grid Embedment (MBFGE) technique. The Co-located Co-variant Method (CCM) is used to simulate this loop in PHOENICS. Extensive experimental and CFD studies have been conducted on single phase natural circulation in a rectangular loop. The paper presents the results of three-dimensional CFD analysis for the prediction of steady state behavior in a rectangular loop and its comparison with experimental data. The results of code prediction and readily available experimental data show good agreement. (orig.)

  2. Research of Micro-Rectangular-Channel Flow Based on Lattice Boltzmann Method

    Directory of Open Access Journals (Sweden)

    Xiao Hong

    2013-08-01

    Full Text Available The source codes of Lattice Boltzmann Method (LBM based on the D3Q15 model were developed in the current study. In the simulation process, the pressure boundary conditions were developed and the rectangular micro-channel flow was investigated. The Width-to-Height ratio (W/H is the main influencing parameter of the rectangular micro-channel flow in low Reynolds number condition. A smaller W/H of the rectangular micro-channel results in a greater difference of drag coefficient between LBM simulation data and empirical formula data. On the empirical data of drag coefficient approximating laminar flow, when the Reynolds number is more than 10, the drag coefficients of LBM simulation and empirical data of laminar flow are in substantial agreement. Thus, in more than 10 conditions of Reynolds number, the empirical data on laminar flow can be used in rectangular micro-channel flow.

  3. Performance of dry piston rod sealing systems for piston cross-head compressors; Betriebsverhalten trocken laufender Kolbenstangen-Dichtsysteme von Kreuzkopfkompressoren

    Energy Technology Data Exchange (ETDEWEB)

    Vetter, G. [Univ. Erlangen-Nuernberg (Germany); Felstel, N. [Burckhardt Compression AG, Winterthur (Switzerland)

    2002-11-01

    In view of the high cost of standstill times, demands on reliability of dry process gas compressors are high. At the same time, collective loads are getting higher so that dry sealing systems tend to be designed for operation near the limit of stability, which is not easy to define in gas-tight contact sealings. Gas-tight sealings are defined as sealing systems with full sealing, both in the axial and radial direction, of all shocks occurring in piston rod sealing systems. Experiments on a special piston cross-head compressor were to provide deeper information. [German] An die trocken laufenden Prozessgasverdichter werden heute aufgrund der ausserordentlich hohen Kosten, die mit einem Produktionsausfall verbunden sein koennen, sehr hohe Anforderungen an ihre Zuverlaessigkeit gestellt. Der gleichzeitig wachsende Bedarf an einer Steigerung des Beanspruchungskollektivs, insbesondere der abzudichtenden Druckdifferenz und der mittleren Kolbengeschwindigkeit, sowie an einer Erhoehung der Wartungsintervalle fuehrt daher zu einer vermehrten Auslegung der trocken laufenden Dichtsysteme im Grenzbereich des stabilen Betriebs. Aufgrund des besonderen Betriebsverhaltens gasdichter Beruehrungsdichtungen, das sich von den vergleichsweise undichten Stroemungsdichtungen deutlich unterscheldet, laesst sich dieser Grenzbereich jedoch nicht einfach definieren. Als ''gasdicht'' werden hierbei Dichtelemente mit einer vollstaendigen (d. h. in axialer und radialer Richtung) Abdichtung saemtlicher Stoesse bezeichnet, wie sie ueblicherweise in Kolbenstangen-Dichtsystemen zum Einsatz gelangen. Aufschluss ueber die Ablaeufe in solchen Dichtsystemen sollten daher experimentelle Untersuchungen an einem hierfuer speziell ausgeruesteten Kreuzkopfkompressor bringen. (orig.)

  4. Improvements of diesel combustion with pilot and main injections at different piston positions; Piston iso wo koryoshita pilot funsha ni yoru diesel nenshono kaizen

    Energy Technology Data Exchange (ETDEWEB)

    Li, C.; Ogawa, H.; Miyamoto, N. [Hokkaido University, Sapporo (Japan); Sakai, A. [Nissan Motor Co. Ltd., Tokyo (Japan)

    2000-06-25

    The fuel spray distribution in a DI diesel engine with a pilot injection was actively controlled by pilot and main fuel injections at different piston positions to avoid the main fuel injection from hitting the pilot flame. A CFD analysis demonstrated that the movement of the piston with a cavity divided by a central lip along the center of the sidewall effectively separated the cores of the pilot and main fuel sprays. The experiments showed that more smoke was emitted with pilot injection in an ordinary cavity without the central lip while smokeless and low NO{sub x} operation was realized with pilot injection in a cavity divided by a central lip even at heavy loads where ordinary operation without pilot injection emitted smoke so much. The indicated specific energy consumption ISEC was a little bit higher with the pilot injection, mainly because of the reduction in the degree of constant volume combustion. With the advanced pilot injection, ISEC was improved more than that with the retarded pilot injection while the NO{sub x} is a little higher than the retarded pilot injection maintaining still much lower than in ordinary operation. (author)

  5. Investigation into Piston-Slap Force under Friction and Connecting Rod Effects of Diesel Engine

    OpenAIRE

    Fuadi Noor Balia; Muhammad Ridha; Shahruddin Mahzan; Abas AB Wahab

    2011-01-01

    In this paper, a dynamics analysis of diesel engine through investigation of the piston-slap force by considering the friction and connecting rod effects is presented. A single-cylinder of 500 cc Diesel Engine’s mechanism was examined. The position, velocity and acceleration of the pins and the center of mass for each linkage were calculated by using vector analysis principles. The governing equations of the forces and moments were derived based on the Cartesian coordinate principles, and sol...

  6. Forward Kinematic Analysis of Tip-Tilt-Piston Parallel Manipulator using Secant-Bootstrap Method

    OpenAIRE

    Majidian, A.; Amani, A.; Golipour, M.; Amraei, A.

    2014-01-01

    This paper, deals with application of the Secant-Bootstrap Method (SBM) to solve the Closed-form forward kinematics of a new three degree-of-freedom (DOF) parallel manipulator with inextensible limbs and base-mounted actuators. The manipulator has higher resolution and precision than the existing three DOF mechanisms with extensible limbs. This methodology has been utilized to achieve approximate solutions for nonlinear equations of kinematic of Tip-Tilt-Piston (T.T.P) Parallel Manipulator. T...

  7. Instantaneous engine frictional torque, its components and piston assembly friction. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, F.A. [ed.] [Argonne National Lab., IL (United States); Henein, N.A. [Wayne State Univ., Detroit, MI (United States). Center for Automotive Research

    1992-05-01

    The overall goal of this report is to document the work done to determine the instantaneous frictional torque of internal combustion engine by using a new approach known as (P-{omega}) method developed at Wayne State University. The emphasis has been to improve the accuracy of the method, and apply it to both diesel and gasoline engines under different operating conditions. Also work included an investigation to determine the effect of using advanced materials and techniques to coat the piston rings on the instantaneous engine frictional torque and the piston assembly friction. The errors in measuring the angular velocity, {omega}, have been determined and found to be caused by variations in the divisions within one encoder, encoder-to-encoder variations, misalignment within the encoder itself and misalignment between the encoder and crankshaft. The errors in measuring the cylinder gas pressure, P, have been determined and found to be caused by transducer-to-transducer variations, zero drift, thermal stresses and lack of linearity. The ability of the (P-{omega}) method in determining the frictional torque of many engine components has been demonstrated. These components include valve train, fuel injection pump with and without fuel injection, and piston with and without different ring combinations. The emphasis in this part of the research program has been on the piston-ring assembly friction. The effects of load and other operating variables on IFT have been determined. The motoring test, which is widely used in industry to measure engine friction has been found to be inaccurate. The errors have been determined at different loads.

  8. The behaviour of inlet roughness in lubrication of piston ring-cylinder liner

    Institute of Scientific and Technical Information of China (English)

    KristianTφNDER

    2001-01-01

    The improvement of lubrication of piston ring-cyinder liner is always in demand, andsurface roughness behaviour plays a very important role. The present paper will explore this be-haviour and investigate how the inlet roughness of ring influences the lubrication of pistonring-cylinder. The quantitative results of this combination of surface roughness on friction force, oilfilm thickness and frictional power loss are given and discussed.

  9. Modelling of the heat load in the piston of turbo diesel engine - continuation

    Directory of Open Access Journals (Sweden)

    Piotr GUSTOF

    2007-01-01

    Full Text Available In this study the mathematical description of characteristic surfaces of the heat exchange of the piston and temperature distribution of the turbo diesel engine at the beginning phase its work was presented. The computations were performed by means of the two-zone combustion model, the boundary conditions of III kind and the finite elements method (MES by using of COSMOS/M program.

  10. Inverstigation on the Separated Turbulent Flow Field in Dual Rectangular Jets

    Institute of Scientific and Technical Information of China (English)

    TANFa-sheng; LIUJie-wei; 等

    2001-01-01

    In the present paper,the flow field of dual rectangular jets was numerically simulated by solving the full Reynolds averaged Navier-Stokes equations,where the RNG κ-ε model and the finite volume method were used.The flow structure in dual rectangular jets and the effects of the velocity were investigated.The numerical results agree qualitatively with the experimental data.

  11. Radio Wave Propagation in Curved Rectangular Tunnels at 5.8 GHz for Metro Applications

    OpenAIRE

    Masson, E.; COCHERIL, Y; COMBEAU, P; AVENEAU, S; BERBINEAU, M; VAUZELLE, R; FAYT, E

    2011-01-01

    The need for wireless communication systems is increasing in the transport domain. These systems have to be operational in every type of environment and particularly tunnels for metro applications. These ones can have rectangular, circular or arch-shaped cross section. Furthermore, they can be straight or curved. This paper presents a new method to model the radio wave propagation in straight tunnels with an arch-shaped cross section and in curved tunnels with a rectangular cross section. The...

  12. Electrostatic force on the rectangular shield wall of a strip transmission line

    Institute of Scientific and Technical Information of China (English)

    向裕民

    2002-01-01

    For a strip transmission line shielded by rectangular walls,the Green's function is helpful to construct the variation expression of the electrostatic energy.Thomson theorem is employed to determine the charge distribution on the strip.The electrostatic force on each side of the rectangular shield wall is achieved by using the principle of virtual work.The results is easy to be obtained by computerized calculation.

  13. Numerical solutions of singular integral equations for planar rectangular interfacial crack in three dimensional bimaterials

    Institute of Scientific and Technical Information of China (English)

    XU Chun-hui; QIN Tai-yan; Nao-Aki Noda

    2007-01-01

    Stress intensity factors for a three dimensional rectangular interfacial crack were considered using the body force method. In the numerical calculations, unknown body force densities were approximated by the products of the fundamental densities and power series; here the fundamental densities are chosen to express singular stress fields due to an interface crack exactly. The calculation shows that the numerical results are satisfied. The stress intensity factors for a rectangular interface crack were indicated accurately with the varying aspect ratio, and bimaterial parameter.

  14. A Single-Point-Fed Wideband Circularly Polarized Rectangular Dielectric Resonator Antenna

    OpenAIRE

    Deqiang Yang; Meng Zou; Jin Pan

    2016-01-01

    A single-point-fed circularly polarized (CP) rectangular dielectric resonator antenna (DRA) with wide CP bandwidth is presented. By using TE111 and TE113 modes of the rectangular DRA, a wideband CP performance is achieved. The coupling slot of the antenna contains a resistor loaded monofilar-spiral-slot and four linear slots. Design concept of the proposed antenna is demonstrated by simulations, and parameter studies are carried out. Prototype of the proposed antenna was fabricated and measur...

  15. A FINITE ELEMENT METHOD WITH RECTANGULAR PERFECTLY MATCHED LAYERS FOR THE SCATTERING FROM CAVITIES

    Institute of Scientific and Technical Information of China (English)

    Deyue Zhang; Fuming Ma; Heping Dong

    2009-01-01

    We develop a finite element method with rectangular perfectly matched layers (PMLs) for the wave scattering from two-dimensional cavities. The unbounded computational domain is truncated to a bounded one by using of a rectangular perfectly matched layer at the open aperture. The PML parameters such as the thickness of the layer and the fictitious medium property are determined through sharp a posteriori error estimates. Numerical experiments are carried out to illustrate the competitive behavior of the proposed method.

  16. Influence of sliding surface roughness and oil temperature on piston ring pack operation of an automotive IC engine

    Science.gov (United States)

    Wolff, A.

    2016-09-01

    In the paper a comprehensive model of a piston ring pack motion on an oil film has been presented. The local oil film thickness can be compared to height of the combined roughness of sliding surfaces of piston rings and cylinder liner. Equations describing the mixed lubrication problem based on the empirical mathematical model formulated in works of Patir, Cheng and Greenwood, Tripp have been combined and used in this paper. The developed model takes the following phenomena into account: hydrodynamic and contact forces, spring and gas forces acting on piston rings. The rings motion concerning low and high temperature of cylinder surface has been compared. These results concern cases of hydrodynamic and mixed lubrication. Changes of oil wetted area and contact zone of piston rings have been shown. In addition the oil film thickness distribution along cylinder liner and all the forces acting on piston rings have been analysed and discussed. The results have been presented in form of relevant diagrams. The developed model and software can be utilized for optimization of piston rings design.

  17. Mixed lubrication analysis for spherical valve plate in piston rod driving type bent-axial-type axial piston pump. 1st Report. Mathematical model; Rod kudo hoshiki shajikushiki piston pump ni okeru kyumen benban no kongo junkatsu kaiseki. 1. Sugaku model

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, K. [Fukui National College of Technology, Fukui (Japan); Kyogoku, K.; Momozono, S.; Nakahara, T. [Tokyo Institute of Technology, Tokyo (Japan)

    1999-06-25

    In order to investigate lubrication characteristics between rotor and spherical valve plate, a mathematical model of rotor motion has been presented for a piston rod driving type bent-axis-type axial piston pump. The forces and the moments acting on the rotor through the piston rod have been derived from geometric analysis of rotor driving mechanism with the piston rod. An analysis model on mixed lubrication between the rotor and the spherical valve plate has been shown using Average-Flow-Model by Patir-Cheng and the contact theory by Greenwood-Tripp, respectively. In addition, bearing part between the rotor and shaft, supporting element of the rotor, has been regarded as squeeze film bearing. The simulation for the lubrication characteristics, such as minimum film thickness, its occurring position and friction loss between the rotor and the spherical valve plate, will be demonstrated in the paper, part 2. (author)

  18. Psyplot: Visualizing rectangular and triangular Climate Model Data with Python

    Science.gov (United States)

    Sommer, Philipp

    2016-04-01

    The development and use of climate models often requires the visualization of geo-referenced data. Creating visualizations should be fast, attractive, flexible, easily applicable and easily reproducible. There is a wide range of software tools available for visualizing raster data, but they often are inaccessible to many users (e.g. because they are difficult to use in a script or have low flexibility). In order to facilitate easy visualization of geo-referenced data, we developed a new framework called "psyplot," which can aid earth system scientists with their daily work. It is purely written in the programming language Python and primarily built upon the python packages matplotlib, cartopy and xray. The package can visualize data stored on the hard disk (e.g. NetCDF, GeoTIFF, any other file format supported by the xray package), or directly from the memory or Climate Data Operators (CDOs). Furthermore, data can be visualized on a rectangular grid (following or not following the CF Conventions) and on a triangular grid (following the CF or UGRID Conventions). Psyplot visualizes 2D scalar and vector fields, enabling the user to easily manage and format multiple plots at the same time, and to export the plots into all common picture formats and movies covered by the matplotlib package. The package can currently be used in an interactive python session or in python scripts, and will soon be developed for use with a graphical user interface (GUI). Finally, the psyplot framework enables flexible configuration, allows easy integration into other scripts that uses matplotlib, and provides a flexible foundation for further development.

  19. Critical Heat Flux in Inclined Rectangular Narrow Gaps

    Energy Technology Data Exchange (ETDEWEB)

    Jeong J. Kim; Yong H. Kim; Seong J. Kim; Sang W. Noh; Kune Y. Suh; Joy L. Rempe; Fan-Bill Cheung; Sang B. Kim

    2004-06-01

    In light of the TMI-2 accident, in which the reactor vessel lower head survived the attack by molten core material, the in-vessel retention strategy was suggested to benefit from cooling the debris through a gap between the lower head and the core material. The GAMMA 1D (Gap Apparatus Mitigating Melt Attack One Dimensional) tests were conducted to investigate the critical heat flux (CHF) in narrow gaps with varying surface orientations. The CHF in an inclined gap, especially in case of the downward-facing narrow gap, is dictated by bubble behavior because the departing bubbles are squeezed. The orientation angle affects the bubble layer and escape of the bubbles from the narrow gap. The test parameters include gap sizes of 1, 2, 5 and 10 mm and the open periphery, and the orientation angles range from the fully downward-facing (180o) to the vertical (90o) position. The 15 ×35 mm copper test section was electrically heated by the thin film resistor on the back. The heater assembly was installed to the tip of the rotating arm in the heated water pool at the atmospheric pressure. The bubble behavior was photographed utilizing a high-speed camera through the Pyrex glass spacer. It was observed that the CHF decreased as the surface inclination angle increased and as the gap size decreased in most of the cases. However, the opposing results were obtained at certain surface orientations and gap sizes. Transition angles, at which the CHF changed in a rapid slope, were also detected, which is consistent with the existing literature. A semi-empirical CHF correlation was developed for the inclined narrow rectangular channels through dimensional analysis. The correlation provides with best-estimate CHF values for realistically assessing the thermal margin to failure of the lower head during a severe accident involving relocation of the core material.

  20. Overview of Multi-Kilowatt Free-Piston Stirling Power Conversion Research at Glenn Research Center

    Science.gov (United States)

    Geng, Steven M.; Mason, Lee S.; Dyson, Rodger W.; Penswick, L. Barry

    2008-01-01

    As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1 kW class free-piston Stirling convertors and a pair of commercially available pressure wave generators (which will be plumbed together to create a high power Stirling linear alternator test rig) have been procured for in-house testing at Glenn Research Center (GRC). Delivery of both the Stirling convertors and the linear alternator test rig is expected by October 2007. The 1 kW class free-piston Stirling convertors will be tested at GRC to map and verify performance. The convertors will later be modified to operate with a NaK liquid metal pumped loop for thermal energy input. The high power linear alternator test rig will be used to map and verify high power Stirling linear alternator performance and to develop power management and distribution (PMAD) methods and techniques. This paper provides an overview of the multi-kilowatt free-piston Stirling power conversion work being performed at GRC.