Rapid calculations of time-harmonic nearfield pressures produced by rectangular pistons.
McGough, Robert J
2004-05-01
A rapid method for calculating the nearfield pressure distribution generated by a rectangular piston is derived for time-harmonic excitations. This rapid approach improves the numerical performance relative to the impulse response with an equivalent integral expression that removes the numerical singularities caused by inverse trigonometric functions. The resulting errors are demonstrated in pressure field calculations using the time-harmonic impulse response solution for a rectangular source 5 wavelengths wide by 7.5 wavelengths high. Simulations using this source geometry show that the rapid method eliminates the singularities introduced by the impulse response. The results of pressure field computations are then evaluated in terms of relative errors and computational speeds. The results show that, when the same number of Gauss abscissas are applied to both approaches for time-harmonic pressure field calculations, the rapid method is consistently faster than the impulse response, and the rapid method consistently produces smaller maximum errors than the impulse response. For specified maximum error values of 10% and 1%, the rapid method is 2.6 times faster than the impulse response for pressure field calculations performed on a 61 by 101 point grid. The rapid approach achieves even greater reductions in the computation time for smaller errors and larger grids. PMID:15139602
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 is...
Cavalcanti, R. M.
2003-01-01
We consider a massless scalar field obeying Dirichlet boundary conditions on the walls of a two-dimensional L x b rectangular box, divided by a movable partition (piston) into two compartments of dimensions a x b and (L-a) x b. We compute the Casimir force on the piston in the limit L -> infinity. Regardless of the value of a/b, the piston is attracted to the nearest end of the box. Asymptotic expressions for the Casimir force on the piston are derived for a > b.
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.
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.
49 CFR 230.93 - Pistons and piston rods.
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...
Piston and connecting rod assembly
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.
Three-dimensional behavior of apodized nontelecentric focusing systems.
Martínez-Corral, M; Muñoz-Escrivá, L; Pons, A
2001-07-01
The scalar field in the focal volume of nontelecentric apodized focusing systems cannot be accurately described by the Debye integral representation. By use of the Fresnel-Kirchhoff diffraction formula it is found that, if the aperture stop is axially displaced, the focal-volume structure is tuned. We analyze the influence of the apodizing function and find that, whereas axially superresolving pupil filters are highly sensitive to the focal-volume reshaping effect, axially apodizing filters are more inclined to the focal-shift effect. PMID:11958254
RING-APODIZED VORTEX CORONAGRAPHS FOR OBSCURED TELESCOPES. I. TRANSMISSIVE RING APODIZERS
International Nuclear Information System (INIS)
The vortex coronagraph (VC) is a new generation small inner working angle (IWA) coronagraph currently offered on various 8 m class ground-based telescopes. On these observing platforms, the current level of performance is not limited by the intrinsic properties of actual vortex devices, but by wavefront control residuals and incoherent background (e.g., thermal emission of the sky), or the light diffracted by the imprint of the secondary mirror and support structures on the telescope pupil. In the particular case of unfriendly apertures (mainly large central obscuration) when very high contrast is needed (e.g., direct imaging of older exoplanets with extremely large telescopes or space-based coronagraphs), a simple VC, like most coronagraphs, cannot deliver its nominal performance because of the contamination due to the diffraction from the obscured part of the pupil. Here, we propose a novel yet simple concept that circumvents this problem. We combine a vortex phase mask in the image plane of a high-contrast instrument with a single pupil-based amplitude ring apodizer, tailor-made to exploit the unique convolution properties of the VC at the Lyot-stop plane. We show that such a ring-apodized vortex coronagraph (RAVC) restores the perfect attenuation property of the VC regardless of the size of the central obscuration, and for any (even) topological charge of the vortex. More importantly, the RAVC maintains the IWA and conserves a fairly high throughput, which are signature properties of the VC
Free piston inertia compressor
Richards, William D. C.; Bilodeau, Denis; Marusak, Thomas; Dutram, Jr., Leonard; Brady, Joseph
1981-01-01
A free piston inertia compressor comprises a piston assembly including a connecting rod having pistons on both ends, the cylinder being split into two substantially identical portions by a seal through which the connecting rod passes. Vents in the cylinder wall are provided near the seal to permit gas to excape the cylinder until the piston covers the vent whereupon the remaining gas in the cylinder functions as a gas spring and cushions the piston against impact on the seal. The connecting rod has a central portion of relatively small diameter providing free play of the connecting rod through the seal and end portions of relatively large diameter providing a limited tolerance between the connecting rod and the seal. Finally, the seal comprises a seal ring assembly consisting of a dampener plate, a free floating seal at the center of the dampener plate and a seal retainer plate in one face of the dampener plate.
Free piston inertia compressor
Richards, W.D.C.; Bilodeau, D.; Marusak, T.; Dutram, L. Jr.; Brady, J.
A free piston inertia compressor comprises a piston assembly including a connecting rod having pistons on both ends, the cylinder being split into two substantially identical portions by a seal through which the connecting rod passes. Vents in the cylinder wall are provided near the seal to permit gas to escape the cylinder until the piston covers the vent whereupon the remaining gas in the cylinder functions as a gas spring and cushions the piston against impact on the seal. The connecting rod has a central portion of relatively small diameter providing free play of the connecting rod through the seal and end portions of relatively large diameter providing a limited tolerance between the connecting rod and the seal. Finally, the seal comprises a seal ring assembly consisting of a dampener plate, a free floating seal at the center of the dampener plate and a seal retainer plate in one face of the dampener plate.
Apodized RFI filtering of synthetic aperture radar images
Energy Technology Data Exchange (ETDEWEB)
Doerry, Armin Walter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
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).
Cooled spool piston compressor
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.
DEFF Research Database (Denmark)
Rasmussen, Morten Fischer; Christiansen, Thomas Lehrmann; Thomsen, Erik Vilain;
2015-01-01
–column-addressed arrays is an apparent ghost effect in the point spread function caused by edge waves. This paper investigates the origin of the edge waves and the effect of introducing an integrated apodization to reduce the ghost echoes. The performance of a λ/2-pitch 5-MHz 128 + 128 row–column-addressed array...... 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...
Apodization in high-contrast long-slit spectroscopy
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%)...
Relief- and apodized-phase-contrast imaging of biological specimens
Czech Academy of Sciences Publication Activity Database
Pelc, Radek; Hostounský, Z.; Otaki, T.
2008-01-01
Roč. 38, 4 suppl. (2008), s. 1073-1074. ISSN 1225-6773. [Asia-Pacific Microscopy Conference /9./. 02.11.2008-07.11.2008, Jeju] R&D Projects: GA MŠk(CZ) LC06063 Institutional research plan: CEZ:AV0Z50110509 Keywords : cpr1 * phase contrast * microscopy * apodization Subject RIV: BO - Biophysics
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...
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.
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.
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
Apodized Pupil Lyot Coronagraphs for Arbitrary Telescope Apertures
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).
Apodized Pupil Lyot Coronagraph Working Without Lyot Stop
N'Diaye, Mamadou; Cuevas, Salvador
2008-01-01
In the context of high contrast imaging, we propose to evaluate the performance of the Apodized Pupil Lyot Coronagraph (APLC) working without Lyot Stop, namely Stop-less Lyot Coronagraph (SLLC). This coronagraph is a combination of an entrance pupil apodizer and an opaque mask in the following focal plane. However, contrary to APLC, SLLC is amputated by the traditional pupil stop. Our goal is to stress the interest of using this coronagraphic solution, in particular for instruments for which the introduction of a stellar coronagraph with Lyot stop is made impossible. We estimate the intensity attenuation achieved with SLLC and carry out our study with a focus on the case of Gran Telescopio Canarias (GTC). In a first step, numerical simulations are made assuming the absence of any aberration, thereafter SLLC performance is evaluated considering AO corrected wavefronts in our approach for ground-based instruments. SLLC performance proves to be equivalent to that obtained with APLC in presence of AO compensated ...
Strange Horizons: Teaching Usual and Unusual Atmospheric Effects using APOD
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.
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.
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.
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...
Acoustical tweezers using single spherically focused piston, X-cut, and Gaussian beams.
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
Energy Technology Data Exchange (ETDEWEB)
Mohammed, Nazmi A. [Research Center, Smart Village, College of Engineering, Arab Academy for Science, Technology, and Maritime Transport, Cairo (Egypt); Ali, Taha A., E-mail: Taha25@gmail.com; Aly, Moustafa H. [Department of Electronics and Communications Engineering, College of Engineering, Arab Academy for Science, Technology, and Maritime Transport, Cairo (Egypt)
2013-12-15
In this work, different FBG temperature sensors are designed and evaluated with various apodization profiles. Evaluation is done under a wide range of controlling design parameters like sensor length and refractive index modulation amplitude, targeting a remarkable temperature sensing performance. New judgment techniques are introduced such as apodization window roll-off rate, asymptotic sidelobe (SL) decay level, number of SLs, and average SL level (SLav). Evaluation techniques like reflectivity, Full width at Half Maximum (FWHM), and Sidelobe Suppression Ratio (SLSR) are also used. A “New” apodization function is proposed, which achieves better performance like asymptotic decay of 18.4 dB/nm, high SLSR of 60 dB, high channel isolation of 57.9 dB, and narrow FWHM less than 0.15 nm. For a single accurate temperature sensor measurement in extensive noisy environment, optimum results are obtained by the Nuttall apodization profile and the new apodization function, which have remarkable SLSR. For a quasi-distributed FBG temperature sensor the Barthann and the new apodization profiles obtain optimum results. Barthann achieves a high asymptotic decay of 40 dB/nm, a narrow FWHM (less than 25 GHZ), a very low SLav of −45.3 dB, high isolation of 44.6 dB, and a high SLSR of 35 dB. The new apodization function achieves narrow FWHM of 0.177 nm, very low SL of −60.1, very low SLav of −63.6 dB, and very high SLSR of −57.7 dB. A study is performed on including an unapodized sensor among apodized sensors in a quasi-distributed sensing system. Finally, an isolation examination is performed on all the discussed apodizations and a linear relation between temperature and the Bragg wavelength shift is observed experimentally and matched with the simulated results.
International Nuclear Information System (INIS)
In this work, different FBG temperature sensors are designed and evaluated with various apodization profiles. Evaluation is done under a wide range of controlling design parameters like sensor length and refractive index modulation amplitude, targeting a remarkable temperature sensing performance. New judgment techniques are introduced such as apodization window roll-off rate, asymptotic sidelobe (SL) decay level, number of SLs, and average SL level (SLav). Evaluation techniques like reflectivity, Full width at Half Maximum (FWHM), and Sidelobe Suppression Ratio (SLSR) are also used. A “New” apodization function is proposed, which achieves better performance like asymptotic decay of 18.4 dB/nm, high SLSR of 60 dB, high channel isolation of 57.9 dB, and narrow FWHM less than 0.15 nm. For a single accurate temperature sensor measurement in extensive noisy environment, optimum results are obtained by the Nuttall apodization profile and the new apodization function, which have remarkable SLSR. For a quasi-distributed FBG temperature sensor the Barthann and the new apodization profiles obtain optimum results. Barthann achieves a high asymptotic decay of 40 dB/nm, a narrow FWHM (less than 25 GHZ), a very low SLav of −45.3 dB, high isolation of 44.6 dB, and a high SLSR of 35 dB. The new apodization function achieves narrow FWHM of 0.177 nm, very low SL of −60.1, very low SLav of −63.6 dB, and very high SLSR of −57.7 dB. A study is performed on including an unapodized sensor among apodized sensors in a quasi-distributed sensing system. Finally, an isolation examination is performed on all the discussed apodizations and a linear relation between temperature and the Bragg wavelength shift is observed experimentally and matched with the simulated results
Composites applied for pistons
Wieczorek J.; Śleziona J.; Dyzia M.; Dolata-Grosz A.
2007-01-01
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 affirm...
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.
Internal combustion piston engines
Energy Technology Data Exchange (ETDEWEB)
Segaser, C.L.
1977-07-01
Current worldwide production of internal combustion piston engines includes many diversified types of designs and a very broad range of sizes. Engine sizes range from a few horsepower in small mobile units to over 40,000 brake horsepower in large stationary and marine units. The key characteristics of internal combustion piston engines considered appropriate for use as prime movers in Integrated Community Energy Systems (ICES) are evaluated. The categories of engines considered include spark-ignition gas engines, compression-ignition oil (diesel) engines, and dual-fuel engines. The engines are evaluated with respect to full-load and part-load performance characteristics, reliability, environmental concerns, estimated 1976 cost data, and current and future status of development. The largest internal combustion piston engines manufactured in the United States range up to 13,540 rated brake horsepower. Future development efforts are anticipated to result in a 20 to 25% increase in brake horsepower without increase in or loss of weight, economy, reliability, or life expectancy, predicated on a simple extension of current development trends.
Improved achromatization of phase mask coronagraphs using colored apodization
N'diaye, M.; Dohlen, K.; Cuevas, S.; Soummer, R.; Sánchez-Pérez, C.; Zamkotsian, F.
2012-02-01
Context. 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 ~ λ0/D where λ0 denotes the central wavelength of the spectral range Δλ), good achromaticity, and high starlight rejection, typically reaching a 106 contrast at 5 λ0/D from the star over a spectral bandwidth Δλ/λ0 of 25% (similar to H-band). This last value proves to be encouraging for broadband imaging of young and warm Jupiter-like planets. Aims: Contrast levels higher than 106 are, however, required for observing older and/or less massive companions over a finite spectral bandwidth. An achromatization improvement of the DZPM coronagraph is therefore mandatory to reach such good performance. Methods: In its design, the DZPM coronagraph uses a gray (or achromatic) apodization. We replaced it by a colored apodization to increase the performance of this coronagraphic system over a wide spectral range. This innovative concept, called colored apodizer phase mask (CAPM) coronagraph, is defined to reach the highest contrast in the exoplanet search area. Once this has been done, we study the performance of the CAPM coronagraph in the presence of different errors to evaluate the sensitivity of our concept. Results: A 2.5 contrast gain is estimated from the performance provided by the CAPM coronagraph with respect to that of the DZPM coronagraph. A 2.2 × 10-8 intensity level at 5 λ0/D separation is then theoretically achieved with the CAPM coronagraph in the presence of a clear circular aperture and a 25% bandwidth. In addition, our studies show that our concept is less sensitive to low than to high-order aberrations for a given value of rms wavefront errors.
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)
49 CFR 229.55 - Piston travel.
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...
Apodized grating coupler using fully-etched nanostructures
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).
Casimir Piston of Real Materials and its Application to Multi-Layer Models
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.
Apodized vortex coronagraph designs for segmented aperture telescopes
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.
Sum-type Kaiser-Bessel windows for apodized antenna arrays
Anukhin, I. P.; Lukin, V. V.; Ponomarenko, N. N.; Zelensky, A. A.; Saramaki, Tapio; Zbaida, K.
1997-01-01
A class of sum-type Kaiser-Bessel windows is introduced. These windows are optimized for improving the performance of apodized array patterns. Compared with the basic Kaiser-Bessel windows, the proposed windows are shown provide several benefits.
An Apodized Kepler Periodogram for Separating Planetary and Stellar Activity Signals
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. ...
49 CFR 230.76 - Piston travel.
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....
Properties of length-apodized phase-shifted lpgs operating at the phase matching turning point
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 ...
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...
PIZZA: a phase-induced zonal Zernike apodization designed for stellar coronagraphy
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.
Integral Ring Carbon-Carbon Piston
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.
Performance characterization of a broadband vector Apodizing Phase Plate coronagraph
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...
Improved achromatization of phase mask coronagraphs using colored apodization
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...
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....
Janjic, Milan
2007-01-01
In the first section of this paper we prove a theorem for the number of columns of a rectangular area that are identical to the given one. In the next section we apply this theorem to derive several combinatorial identities by counting specified subsets of a finite set.
Piston-assisted charge pumping
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.
Casimir force between integrable and chaotic pistons
Alvarez, Ezequiel; Mazzitelli, Francisco Diego; Monastra, Alejandro G.; Wisniacki, Diego A.
2010-01-01
We have computed numerically the Casimir force between two identical pistons inside a very long cylinder, considering different shapes for the pistons. The pistons can be considered as quantum billiards, whose spectrum determines the vacuum force. The smooth part of the spectrum fixes the force at short distances, and depends only on geometric quantities like the area or perimeter of the piston. However, correcting terms to the force, coming from the oscillating part of the spectrum which is ...
Improved extension of depth-of-field performance by apodized wavefront coding
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.
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)
Linear Motor Free Piston Compressor
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.
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....
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)
Detuning in apodized point-by-point fiber Bragg gratings: insights into the grating morphology.
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
Apodized annular-aperture logarithmic axicon: smoothness and uniformity of intensity distributions.
Jaroszewicz, Z; Sochacki, J; Kolodziejczyk, A; Staronski, L R
1993-11-15
We show that the apodized annular-aperture logarithmic axicon preserves excellent uniformity of the on-axis intensity, energy flow, and lateral resolution. Numerical evaluation of the Fresnel diffraction integral leads to results very close to geometrical-optics predictions. Once again the geometrical law of energy conservation turns out to be a useful tool in designing axicons. PMID:19829438
Sivaramakrishnan, Anand; Greenbaum, Alexandra Z.; Carr, G. Lawrence; Smith, Randy J.; Xi, Xiaoxiang; Zimmerman, Neil T.
2013-09-01
High contrast imaging can use pupil apodizers to suppress diffracted starlight from a bright source in order to observe its environs. Metallic half-tone dot transmissive apodizers were developed for the Gemini Planet Imager (GPI) and ESO SPHERE coronagraphs for use in the near-IR. Dot sizes on the scale of the wavelength of the light often result in unexpected variations in the optical transmission vs. superficial dot density relation. We measured 5 and 10 micron half-tone microdot screens' transmissions between 550 -1050 nm to prepare to fabricate apodizations that mitigate diffraction by segments gaps and spiders on future large space telescopes. We utilized slow test beams (f/40, f/80) to estimate the on-axis (far-field, or zero-order) transmission of test patches using a Fourier Transform Spectrograph on Beamline U10B at Brookhaven National Laboratory's National Synchrotron Light Source (BNL NSLS). We also modified our previous GPI IR characterization hardware and methods for this experiment. Our measurements show an internal consistency of 0.1% in transmission, a factor of 5 better than our near-IR GPI work on the NSLS U4IR beamline. The systematics of the set-up appeared to limit the absolute calibration for our f/40 data on the 50-patch, maximum Optical Density 3 (OD3), sample. Credible measurements of transmissions down to about 3% transmission were achieved for this sample. Future work on apodizers for obstructed and segmented primary mirror coronagraphs will require configurations that mimic the intended diffractive configurations closely in order to tune apodizer fabrication to any particular application, and measure chromatic effects in representative diffractive regimes. Further experimental refinements are needed to measure the densest test patches which possess transmissions less than a few percent. The new NSLS-II should provide much greater spectral stability of its synchrotron beam, which will improve measurement accuracy and reduce systematics.
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.
Rectangular spectral collocation
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.
Carbon/Carbon Pistons for Internal Combustion Engines
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.
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...
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.
Reciprocating piston pump system with screw drive
Perkins, Gerald S. (Inventor); Moore, Nicholas R. (Inventor)
1981-01-01
A pump system of the reciprocating piston type is described, which facilitates direct motor drive and cylinder sealing. A threaded middle potion of the piston is engaged by a nut connected to rotate with the rotor of an electric motor, in a manner that minimizes loading on the rotor by the use of a coupling that transmits torque to the nut but permits it to shift axially and radially with respect to the rotor. The nut has a threaded hydrostatic bearing for engaging the threaded piston portion, with an oil-carrying groove in the nut being interrupted. A fluid emitting seal located at the entrance to each cylinder, can serve to center the piston within the cylinder, wash the piston, and to aid in sealing. The piston can have a long stroke to diameter ratio to minimize reciprocations and wear on valves at high pressures. The voltage applied to the motor can be reversed prior to the piston reaching the end of its stroke, to permit pressure on the piston to aid in reversing the motor.
Collapsible pistons for light-gas guns
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%.
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...
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...
Inverse-Gaussian-Apodized Fiber Bragg Grating for Dual Wavelength Lasing
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.
Calculation of pressure fields from arbitrarily shaped, apodized, and excited ultrasound transducers
Jensen, Jørgen Arendt; Svendsen, Niels Bruun
1992-01-01
A method for simulation of pulsed pressure fields from arbitrarily shaped, apodized and excited ultrasound transducers is suggested. It relies on the Tupholme-Stepanishen method for calculating pulsed pressure fields, and can also handle the continuous wave and pulse-echo case. The field is calculated by dividing the surface into small rectangles and then Summing their response. A fast calculation is obtained by using the far-field approximation. Examples of the accuracy of the approach and a...
Dynamics of crank-piston mechanisms
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.
Casimir force between integrable and chaotic pistons
International Nuclear Information System (INIS)
We have computed numerically the Casimir force between two identical pistons inside a very long cylinder, considering different shapes for the pistons. The pistons can be considered quantum billiards, whose spectrum determines the vacuum force. The smooth part of the spectrum fixes the force at short distances and depends only on geometric quantities like the area or perimeter of the piston. However, correcting terms to the force, coming from the oscillating part of the spectrum which is related to the classical dynamics of the billiard, could be qualitatively different for classically integrable or chaotic systems. We have performed a detailed numerical analysis of the corresponding Casimir force for pistons with regular and chaotic classical dynamics. For a family of stadium billiards, we have found that the correcting part of the Casimir force presents a sudden change in the transition from regular to chaotic geometries. This suggests that there could be signatures of quantum chaos in the Casimir effect.
An apodized Kepler periodogram for separating planetary and stellar activity signals
Gregory, Philip C.
2016-05-01
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 centre can distinguish planetary signals from SA signals on the basis of the span of the apodization window. The general model for m AK signals includes a linear regression term between RV and the SA 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 Markov chain Monte Carlo 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 SA diagnostics. In the current implementation, the AK method achieved a reduction in SA noise by a factor of approximately 6. Final parameter estimates for the planetary candidates are derived from fits that include AK signals to model the SA components and simple Keplerians to model the planetary candidates. Preliminary results are also reported for AK models augmented by a moving average component that allows for correlations in the residuals.
A Characterization of Rectangular Distributions
Terrell, George R.
1983-01-01
It is well known that the smaller and the larger of a random sample of size two are positively correlated. The coefficient of correlation is at most one-half, and the upper bound is attained only for rectangular distributions.
Heat transfer during piston compression
International Nuclear Information System (INIS)
An experimental and theoretical study has been carried out to determine the unsteady heat transfer from a nonreacting gas to the end wall of a channel during the piston compression of a single stroke. A thin platinum film resistance thermometer records the surface temperature of the wall during the compression. A conduction analysis in the wall, subject to the measured surface temperature variation, then yields the unsteady heat flux. A separate analysis based on the solution of the laminar boundary layer equations in the gas provides an independent determination of the heat flux. The two results are shown to be in good agreement. This is true for measurements that were made in air and in argon. Results for the heat transfer coefficient as a function of time are also presented and exhibit a nonmonotonic variation
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.
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.
Numerical Simulation of Piston Ring Lubrication
DEFF Research Database (Denmark)
Felter, Christian Lotz
2006-01-01
and the angle between the normals of the solid and the free surface. The numerical model is compared with the results from an analytical solution of Reynolds equation for a fixed incline slider bearing. Then results from a more compli- cated simulation of piston ring lubrication is given and discussed.......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...... extended to include also the oil film outside the piston rings. The numerical model consists of a 2D free surface code that solves the time dependent compressible Navier-Stokes equations. The equations are cast in Lagrangian form and discretized by a meshfree moving least squares method using the primitive...
Spherical Joint Piston and Connecting Rod Developed
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
Emergency braking for free piston energy converters
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...
Uji Unjuk Kerja Pompa Pedal Multi Piston
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...
Fluid structure interaction in piston diaphragm pumps
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.
Successive normalization of rectangular arrays
Olshen, Richard A; 10.1214/09-AOS743
2010-01-01
Standard statistical techniques often require transforming data to have mean 0 and standard deviation 1. Typically, this process of "standardization" or "normalization" is applied across subjects when each subject produces a single number. High throughput genomic and financial data often come as rectangular arrays where each coordinate in one direction concerns subjects who might have different status (case or control, say), and each coordinate in the other designates "outcome" for a specific feature, for example, "gene," "polymorphic site" or some aspect of financial profile. It may happen, when analyzing data that arrive as a rectangular array, that one requires BOTH the subjects and the features to be "on the same footing." Thus there may be a need to standardize across rows and columns of the rectangular matrix. There arises the question as to how to achieve this double normalization. We propose and investigate the convergence of what seems to us a natural approach to successive normalization which we lea...
Synchronizability of random rectangular graphs
Energy Technology Data Exchange (ETDEWEB)
Estrada, Ernesto, E-mail: ernesto.estrada@strath.ac.uk; Chen, Guanrong [Department of Mathematics & Statistics, University of Strathclyde, 26 Richmond Street, Glasgow G1 1XQ, United Kingdom and Department of Electronic Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon (Hong Kong)
2015-08-15
Random rectangular graphs (RRGs) represent a generalization of the random geometric graphs in which the nodes are embedded into hyperrectangles instead of on hypercubes. The synchronizability of RRG model is studied. Both upper and lower bounds of the eigenratio of the network Laplacian matrix are determined analytically. It is proven that as the rectangular network is more elongated, the network becomes harder to synchronize. The synchronization processing behavior of a RRG network of chaotic Lorenz system nodes is numerically investigated, showing complete consistence with the theoretical results.
Synchronizability of random rectangular graphs
International Nuclear Information System (INIS)
Random rectangular graphs (RRGs) represent a generalization of the random geometric graphs in which the nodes are embedded into hyperrectangles instead of on hypercubes. The synchronizability of RRG model is studied. Both upper and lower bounds of the eigenratio of the network Laplacian matrix are determined analytically. It is proven that as the rectangular network is more elongated, the network becomes harder to synchronize. The synchronization processing behavior of a RRG network of chaotic Lorenz system nodes is numerically investigated, showing complete consistence with the theoretical 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.
Aime, C.
2013-10-01
Context. This study focuses on an instrument able to monitor the corona close to the solar limb. Aims: We study the performance of externally occulted solar coronagraphs. We compute the shape of the umbra and penumbra produced by the occulter at the entrance aperture of the telescope and compare levels of rejection obtained for a circular occulter with a sharp or smooth transmission at the edge. Methods: We show that the umbral pattern in an externally occulted coronagraph can be written as a convolution product between the occulter diffraction pattern and an image of the Sun. We then focus on the analysis to circular symmetric occulters. We first derive an analytical expression using two Lommel series for the Fresnel diffraction pattern produced by a sharp-edged circular occulter. Two different expressions are used for inside and outside the occulter's geometric shadow. We verify that a numerical approach that directly solves the Huygens-Fresnel integral gives the same result. This suggests that the numerical computation can be used for a circular occulter with any variable transmission. Results: With the objective of observing the solar corona a few minutes from limb, a sharp-edged circular occulter of a few meters cannot produce an umbra darker than 10-4 of the direct sunlight. The same occulter, having an apodization zone of a few percent of the diameter (3 cm for a 1.5 m occulter), darkers the umbra down to 10-8 of the direct sunlight for linear transmission and to 10-12 for Sonine or cosine bell transmissions. An investigation for an apodized occulter with manufacturing defaults is quickly performed. Conclusions: It has been possible to numerically demonstrate the large superiority of apodized circular occulters with respect to the sharp-edged ones. These occulters allow the theoretical observation of the very limb-close corona with not yet obtained contrast ratios.
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.
DEFF Research Database (Denmark)
Deyerl, Hans-Jürgen; Plougmann, Nikolai; Jensen, Jesper Bo Damm; Floreani, Filip; Sørensen, Henrik Rokkjær; Kristensen, Martin
2004-01-01
The polarization control method offers a flexible, robust, and low-cost route for the parallel fabrication of gratings with complex apodization profiles including several discrete phase shifts and chirp. The performance of several test gratings is evaluated in terms of their spectral response and...... compared with theoretical predictions. Short gratings with sidelobe-suppression levels in excess of 32 dB and transmission dips lower than 80 dB have been realized. Finally, most of the devices fabricated by the polarization control method show comparable quality to gratings manufactured by far more...
Systematic parametric design/calculation of the piston rod unit
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.
Drive piston assembly for a valve actuator assembly
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.
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......Pa, and the sensitivity was 0.299 ± 0.090 V/Pa. The nearest neighbor crosstalk level was -23.9 ± 3.7 dB, while the transmit-to-receive-elements crosstalk level was -40.2 ± 3.5 dB. Imaging of a 0.3-mm-diameter steel wire using synthetic transmit focusing with 62 single-element emissions demonstrated axial and lateral...... FWHMs of 0.71 mm and 1.79 mm (f-number: 1.4), respectively, compared with simulated axial and lateral FWHMs of 0.69 mm and 1.76 mm. The dominant ghost echo was reduced by 15.8 dB in measurements using the integrated apodization compared with the disabled configuration. The effect was reproduced...
Design of off-axis mirrors for the phase-induced amplitude apodization complex mask coronagraph
Pluzhnik, Eugene; Guyon, Olivier; Belikov, Ruslan; Bendek, Eduardo
2016-01-01
The phase-induced amplitude apodization complex mask coronagraph (PIAACMC) provides an efficient way to control diffraction propagation effects caused by the central obstruction/segmented mirrors of the telescope. PIAACMC can be optimized in a way that takes into account both chromatic diffraction effects caused by the telescope obstructed aperture and the tip-tilt sensitivity of the coronagraph. As a result, unlike classic phase-induced amplitude apodization (PIAA), the PIAACMC mirror shapes are often slightly asymmetric even for an on-axis configuration and require more care in calculating off-axis shapes when an off-axis configuration is preferred. A method to design off-axis PIAA mirror shapes given an on-axis mirror design is presented. The algorithm is based on geometrical ray tracing and is able to calculate off-axis PIAA mirror shapes for an arbitrary geometry of the input and output beams. The method is demonstrated using the third generation PIAACMC design for WFIRST-AFTA telescope. Geometrical optics design issues related to the off-axis diffraction propagation effects are also discussed.
Exoplanets imaging with a Phase-Induced Amplitude Apodization Coronagraph - I. Principle
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...
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.
Insulated Piston Heads for Diesel Engines
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.
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.
Piston-rotaxanes as molecular shock absorbers.
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
Engine piston having an insulating air gap
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.
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.
Flows for rectangular matrix models
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...
Internal Cooling of the Piston Rod in Non-Lubricated Piston Compressors
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...
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.
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.
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.
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.
How Hot Can a Fire Piston Get?
Scott-Brown, J. A.; Cunningham, O. A.; Goad, B. C.
2010-01-01
The fire piston is just a sealed syringe containing a small amount of tinder. When the plunger is forced downwards, the air inside is compressed and heats up, setting fire to the tinder. It has been used as a convenient and portable way of starting fires "over a wide area from northern Burma and Siam through the Malay Peninsula and the Malayan…
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)
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.
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.
A SAR sidelobe suppression algorithm based on modified spatially variant apodization
Institute of Scientific and Technical Information of China (English)
无
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.
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)
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.
Laser light stripe measurements assure correct piston assembly
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.
Numerical calculation of the force on some Generalized Casimir Pistons
Energy Technology Data Exchange (ETDEWEB)
Schaden, Martin, E-mail: mschaden@andromeda.rutgers.ed [Department of Physics, Rutgers University, Newark, NJ 07102 (United States)
2009-04-01
In this talk I presented numerical calculations of the Casimir force due to a scalar field on a piston in a cylinder of radius tau with a spherical cap of radius R > tau. Geometrical subtractions give a finite interaction energy. Due to reflection positivity, the vacuum force on the piston by a scalar field satisfying Dirichlet boundary conditions is attractive for these geometries, but the strength and short-distance behavior of the force depends strongly on the shape of the piston casing. For a cylindrical casing with a hemispherical head of large radius, the attractive force on the piston is inversely proportional to the square of the height of the piston.
Quantum noise in rectangular cavities
International Nuclear Information System (INIS)
In this paper the authors calculate the energy spectrum of vacuum fluctuations for a massless scalar field which satisfies boundary conditions inside a wave guide or a rectangular box. The spectrum is piecewise continuous in the first case and discrete in the second, and exhibits resonances which correspond, as expected, to the energy levels of a particle in a box (with the difference that all these levels are occupied). Since it is known that these fluctuations exhibit a very slow convergence to a Poisson distribution, we conjecture that a realistic detector must find severe quantum vacuum deviations from white noise, except in the non-realistic limit of extremely high frequencies
Quantum noise in rectangular cavities
Energy Technology Data Exchange (ETDEWEB)
Villarreal, C.; Jauregui, R.; Hacyan, S.; Cocho, G. (Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Fisica)
1992-10-10
In this paper the authors calculate the energy spectrum of vacuum fluctuations for a massless scalar field which satisfies boundary conditions inside a wave guide or a rectangular box. The spectrum is piecewise continuous in the first case and discrete in the second, and exhibits resonances which correspond, as expected, to the energy levels of a particle in a box (with the difference that all these levels are occupied). Since it is known that these fluctuations exhibit a very slow convergence to a Poisson distribution, we conjecture that a realistic detector must find severe quantum vacuum deviations from white noise, except in the non-realistic limit of extremely high frequencies.
Rectangular Decomposition of Binary Images
Czech Academy of Sciences Publication Activity Database
Suk, Tomáš; Höschl, Cyril; Flusser, Jan
Berlin : Springer, 2012 - (Blanc-Talon, J.; Popescu, D.; Philips, W.; Scheunders, P.), s. 213-224 ISBN 978-3-642-33139-8. - (Lecture Notes in Computer Science. 7517). [Advanced Concepts for Intelligent Vision Systems (Acivs 2012). Brno (CZ), 04.09.2012-07.09.2012] R&D Projects: GA ČR GAP103/11/1552 Institutional support: RVO:67985556 Keywords : binary image decomposition * generalized delta-method * distance transformation * quadtree * bipartite graph * image compression * fast convolution Subject RIV: IN - Informatics, Computer Science http://library.utia.cas.cz/separaty/2012/ZOI/suk-rectangular decomposition of binary images.pdf
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.
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 is...
Reduction of HCCI combustion noise through piston crown design
DEFF Research Database (Denmark)
Pedersen, Troels Dyhr; Schramm, Jesper
2010-01-01
further reduced with another piston crown where eight cylindrical volumes were drilled into the piston crown, so that the cylinder liner was not exposed directly to the combustion. A configuration with seven hemispherical volumes was less silent in operation, but still better than the flat piston crown......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...... compression volume into four smaller volumes placed between the perimeter of the piston and the cylinder liner increased the noise to a higher level than that generated with a flat piston crown. This was due to resonance between the four volumes. Using eight volumes instead decreased the noise. The noise was...
Experimental Investigation of Piston Rings for Internal Combustion Engines
DEFF Research Database (Denmark)
Klit, Peder; Vølund, Anders
2008-01-01
absorbed in the bearing. Since the frictional forces are small compared to the rest of the acting forces the rig is designed such that the piston is fixed while the cylinder liner moves. This approach makes it simple to measure the parameters mentioned above by putting the instrumentation in the piston...... 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...... 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 is...
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.
The Casimir Effect for Thick Pistons
Fucci, Guglielmo
2015-01-01
In this work we analyze the Casimir energy and force for a {\\it thick} piston configuration. This study is performed by utilizing the spectral zeta function regularization method. The results we obtain for the Casimir energy and force depend explicitly on the parameters that describe the general self-adjoint boundary conditions imposed. Numerical results for the Casimir force are provided for specific types of boundary conditions and are also compared to the corresponding force on an infinite...
Quantum optomechanical piston engines powered by heat
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...
Cylinder with differential piston for mass measurements
International Nuclear Information System (INIS)
The paper presents a cylinder with differential piston, adapted for measuring the weight of fixed objects such as: fuel tanks (regardless of their capacity), bunkers and silos for all kind of materials, or mobile objects such as: automobiles, trucks, locomotives and railway cars. Although, the cylinder with differential piston is used on a large scale in hydraulic drive or hydraulic control circuits, till now it was not used as constituent part for weight measurements devices. The novelty of the present paper is precisely the use of the device for such purposes. Based on a computation algorithm, the paper presents the general design (assembly), of the device used for weighing important masses (1…. 100 tones). The fundamental idea consist in the fact that, a mass over 10 tones may be weighted with a helicoidally spring subjected to an axial force between 0 and 3000 N, with a deflection of about 30 mm. Simultaneously with the mechanical part, the electronic recording system is also described. The great advantage of the presented device consist in the fact that it can be used in heavy polluted atmosphere or difficult topographic conditions as a result of both the small dimensions and the protection systems adopted. Keywords: cylinder hydraulic with differential piston, hydrostatic pressure, measuring devices
Single-piston alternative to Stirling engines
International Nuclear Information System (INIS)
Highlights: ► Thermodynamic analysis of an unconventional heat engine. ► The engine has a number of advantages compared to state-of-the-art Stirling engines. ► The engine can to be fuelled with “difficult” fuels and used for micro-CHP systems. ► The energy conversion efficiency can be as high as 40–50%. ► A prototype of the engine was demonstrated. -- Abstract: Thermodynamic analysis of an unconventional heat engine was performed. The engine studied has a number of advantages compared to state-of-the-art Stirling engines. The main advantage of the engine proposed is its simplicity. A power piston is integral with a displacer and a heat regenerator. It allows solving the problem of the high-temperature sealing of the piston and the displacer typical of all types of Stirling engines. In addition the design proposed provides ideal use of the displacer volume eliminating heat losses from outside gas circuit. Both strokes of the piston are working ones in contrary to any other types of piston engines. The engine can be considered as maintenance-free as it has no piston rings or any other rubbing components requiring lubrication. The only seal is contactless and wear free. It is located in the cold part of the cylinder. As a result the leakage rate in operation can be one-two orders of magnitude as small as that in Stirling engines. Balancing of the engine is much easy compared to Stirling engines with two reciprocating masses because of the only moving part inside the engine cylinder. The engine suits ideally to be fuelled with “difficult” fuels such as bio oil and can be used as a prime mover for micro-CHP systems. The thermodynamic model developed incorporates non-ideal features of the cycle, such as specific regenerator efficiency, dead volumes and other geometrical parameters of the engine. The model shows that the energy efficiency is highly sensitive to regenerator performance. For realistic geometric and operating parameters and the
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 ...
Numerical simulation of piston leakage over hermetic reciprocating compressors behavior.
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...
A Dynamic Analysis of Free Piston Vuilleumier Cycle Heat Pumps
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...
Improving Free-Piston Stirling Engine Specific Power
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.
The effect of piston bowl temperature on diesel exhaust emissions
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...
Internal position and limit sensor for free piston machines
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.
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.
Stability analysis of free piston Stirling engines
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.
Quantum optomechanical piston engines powered by heat
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.
ac electroosmosis in rectangular microchannels.
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
Successive Standardization of Rectangular Arrays
Directory of Open Access Journals (Sweden)
Richard A. Olshen
2012-02-01
Full Text Available In this note we illustrate and develop further with mathematics and examples, the work on successive standardization (or normalization that is studied earlier by the same authors in [1] and [2]. Thus, we deal with successive iterations applied to rectangular arrays of numbers, where to avoid technical difficulties an array has at least three rows and at least three columns. Without loss, an iteration begins with operations on columns: first subtract the mean of each column; then divide by its standard deviation. The iteration continues with the same two operations done successively for rows. These four operations applied in sequence completes one iteration. One then iterates again, and again, and again, ... In [1] it was argued that if arrays are made up of real numbers, then the set for which convergence of these successive iterations fails has Lebesgue measure 0. The limiting array has row and column means 0, row and column standard deviations 1. A basic result on convergence given in [1] is true, though the argument in [1] is faulty. The result is stated in the form of a theorem here, and the argument for the theorem is correct. Moreover, many graphics given in [1] suggest that except for a set of entries of any array with Lebesgue measure 0, convergence is very rapid, eventually exponentially fast in the number of iterations. Because we learned this set of rules from Bradley Efron, we call it “Efron’s algorithm”. More importantly, the rapidity of convergence is illustrated by numerical examples.
Fluorocarbon seal replaces metal piston ring in low density gas environment
Morath, W. D.; Morgan, N. E.
1967-01-01
Reinforced fluorocarbon cupseal, which provides an integral lip-type seal, replaces the metal piston rings in piston-cylinder configurations used in the compression of low density gases. The fluorocarbon seal may be used as cryogenic compressor piston seals.
Use of rectangular geometry for radon dosimetry
International Nuclear Information System (INIS)
A method is presented for calculating the track density distribution of Radon Alpha particles in the plastic track detectors placed along the wall of a rectangular dosimeter. The track density is taken as proportional to the volume of a sphere of radius 'R', where R is comparable to the range of the alpha particles. This volume has been calculated for a rectangular box of dimensions, a x a x b, as a function of the distance η of the centre of the sphere from the edge of the box. The distribution so obtained has been compared with the experimental track density distribution of Radon Alpha particles found in CN85 plastic track detectors placed along the wall of a rectangular box of 6 x 6 x 8 cm3 in an artificial mine in the laboratory. Conclusions regarding the suitability of rectangular geometry as compared to the cylindrical geometry have been drawn. (author)
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
Random Young diagrams in a Rectangular Box
DEFF Research Database (Denmark)
Beltoft, Dan; Boutillier, Cédric; Enriquez, Nathanaël
We exhibit the limit shape of random Young diagrams having a distribution proportional to the exponential of their area, and confined in a rectangular box. The Ornstein-Uhlenbeck bridge arises from the fluctuations around the limit shape.......We exhibit the limit shape of random Young diagrams having a distribution proportional to the exponential of their area, and confined in a rectangular box. The Ornstein-Uhlenbeck bridge arises from the fluctuations around the limit shape....
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 engin...
Casimir effect for smooth potentials on spherically symmetric pistons
Morales-Almazan, Pedro; Kirsten, Klaus
2015-12-01
In this article we consider a spherical piston modeled by a spherically symmetric potential. The piston is positioned between two spherical shells and the corresponding Casimir energy and force are computed. Zeta function regularization based upon suitable contour integral representations is utilized. A numerical analysis of the Casimir force is provided for a variety of Gaussian like potentials.
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.
TRIBOLOGICAL PERFORMANCE OF PISTON RING IN MARINE DIESEL ENGINE
DEFF Research Database (Denmark)
Imran, Tajammal; Klit, Peder; Felter, Christian;
a reciprocating principle was developed. Tribological parameters such as friction force, thickness of oil film and temperature variation of the piston ring bulk were studied as a function of crankshaft rotational speed, loading of the piston ring and two different types of lubricating oils. Dead...... loading was applied for each experiment. Selected results are presented for friction force, oil film thickness and temperature variation of the piston ring bulk as a function of crankshaft instantaneous position. Results are also compared for two different oils used in this study. Obtained results showed...... that the two dead centers have significant influence on the performance of piston rings under lubricated conditions. It can be concluded that at the dead centers the piston rings will experience a transition from dry friction to hydrodynamic friction with corresponding variation in rotational speed....
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.
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.
Transient Characteristics of Free Piston Vuilleurnier Cycle Heat Pumps
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.
Hot piston ring/cylinder liner materials: Selection and evaluation
Sliney, Harold E.
1988-01-01
In current designs of the automotive (kinematic) Stirling engine, the piston rings are made of a reinforced polymer and are located below the pistons because they cannot withstand the high temperatures in the upper cylinder area. Theoretically, efficiency could be improved if hot piston rings were located near the top of the pistons. Described is a program to select piston ring and cylinder coating materials to test this theory. Candidate materials were screened, then subjected to a pin or disk friction and wear test machine. Tests were performed in hydrogen at specimen temperatures up to 760 C to simulate environmental conditions in the region of the hot piston ring reversal. Based on the results of these tests, a cobalt based alloy, Stellite 6B, was chosen for the piston rings and PS200, which consists of a metal-bonded chromium carbide matrix with dispersed solid lubricants, was chosen as the cylinder coating. Tests of a modified engine and a baseline engine showed that the hot ring reduced specific fuel consumption by up to 7 percent for some operating conditions and averaged about 3 percent for all conditions evaluated. Related applications of high-temperature coatings for shaft seals and as back-up lubricants are also described.
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)
Gao, Guang-Qi; Song, Li-Shuang; Tong, Bin; Li, Guang-Peng
2016-05-18
Carotenoids, which generate yellow, orange, and red colors, are crucial pigments in avian plumage. Investigations into genes associated with carotenoidbased coloration in avian species are important; however, such research is difficult because carotenoids cannot be synthetized in vertebrates as they are only derived from dietary sources. Here, the golden pheasant (Chrysolophus pictus) was used as a model in analysis of candidate gene expression profiles implicated in carotenoid binding and deposition. Using mass and Raman spectrometry to confirm the presence of carotenoids in golden pheasant feathers, we found C40H54O and C40H56O2 in feathers with yellow to red colors, and in the rachis of iridescent feathers. The global gene expression profiles in golden pheasant skins were analyzed by RNA-seq and all six carotenoid binding candidate genes sequenced were studied by realtime PCR. StAR4, GSTA2, Scarb1, and APOD in feather follicles showed different expressions in red breast and orange nape feathers compared with that of iridescent mantle feathers. Further comparison of golden pheasant yellow rump and Lady Amherst's pheasant (Chrysolophus amherstiae) white nape feathers suggested that GSTA2 and APOD played a potential role in carotenoid-based coloration in golden pheasant. PMID:27265652
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.
Loss terms in free-piston Stirling engine models
Gordon, Lloyd B.
1992-01-01
Various models for free piston Stirling engines are reviewed. Initial models were developed primarily for design purposes and to predict operating parameters, especially efficiency. More recently, however, such models have been used to predict engine stability. Free piston Stirling engines have no kinematic constraints and stability may not only be sensitive to the load, but also to various nonlinear loss and spring constraints. The present understanding is reviewed of various loss mechanisms for free piston Stirling engines and how they have been incorporated into engine models is discussed.
Reversible compression of an optical piston through Kramers dynamics
Schnoering, Gabriel
2015-01-01
We study the reversible crossover between stable and bistable phases of an over-damped Brownian bead inside an optical piston. The interaction potentials are solved developing a method based on Kramers' theory that exploits the statistical properties of the stochastic motion of the bead. We evaluate precisely the energy balance of the crossover. We show that the deformation of the optical potentials induced by the compression of the piston is related to a production of heat which measures the non-adiabatic character of the crossover. This reveals how specific thermodynamic processes can be designed and controlled with a high level of precision by tailoring the optical landscapes of the piston.
Experimental Investigation of Piston Rings for Internal Combustion Engines
DEFF Research Database (Denmark)
Christiansen, Jens; Klit, Peder; Vølund, Anders;
2007-01-01
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. The aim of this paper is describe the tribological...... 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...
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.
Neutron collimator with rectangular beam profile
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.
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
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.
Countercurrent flow limitation in narrow rectangular ducts
International Nuclear Information System (INIS)
Countercurrent air-water two phase flow limitation in vertical narrow rectangular ducts was investigated. The scale effect was investigated using three narrow rectangular ducts with different gaps (2 x 100, 5 x 100, 10 x 100 mm). The experimental data showed similar tendency in spite of gap or upper plenum liquid level. The Wallis type correlation with constant C = 0.65 gave a good agreement with the experimental data. A comparison with the prediction by the envelope theory using the Bharathan friction factor correlation was also discussed. (author)
Lossy-Transmission-Line Analysis of Frequency Reconfigurable Rectangular-Ring Microstrip Antenna
Directory of Open Access Journals (Sweden)
Bambang Setia Nugroho
2014-01-01
Full Text Available An analytical model for a frequency reconfigurable rectangular-ring microstrip antenna is proposed. The resonant frequencies and input impedance of the reconfigurable antenna are analyzed using a lossy-transmission-line (LTL model. By making use of Y-admittance matrices, a formulation for the input impedance is analytically derived. The structure of the frequency reconfigurable antenna consists of a rectangular-ring shaped microstrip antenna which is loaded with a rectangular patch in the middle of the rectangular-ring antenna and fed by a microstrip line. RF switches are applied to connect the load to the antenna in order to reconfigure the operating frequencies. By modeling the antenna into a multiport equivalent circuit, the total input impedance is analytically derived to predict the resonant frequencies. To verify the analysis, the model input impedance and reflection coefficient calculation have been compared with the full-wave simulation and measurement results. The proposed model shows good agreement with full-wave simulated and measured results in the range of 1–3 GHz.
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.
Turbocharger with sliding piston, and having vanes and leakage dams
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.
Experimental Investigation of Piston Rings for Internal Combustion Engines
DEFF Research Database (Denmark)
Christiansen, Jens; Klit, Peder; Vølund, Anders; Hwang, Jong-Hyun
One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. A very important condition for describing the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external...... 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...... regimes and the non-uniform oil distribution opens for the possibility of starved conditions for the piston ring bearing. Therefore it is important to measure the oil distribution on the liner as a function of the operating conditions. The amount of lubricant available is reflected in the friction...
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.
Volumetric Efficiency Improvement by Overflow in Rolling Piston Compressor
Wang, Wen; Huang, Gensheng; Zhang, Yilin
2014-01-01
The rotary compressor with rolling piston is a widely used compressor with less clearance volume, while it is minimized from normal scale to meso or micro scale, the input and exit ports dimension is limited by port requirement and lead to a certain clearance volume, therefore, keeping or improving its volume efficiency is an important issue. Although rolling piston compressor is a kind of compact structure compressor, the existence of the clearance volume is inevitable in a compressor, the m...
Gas Vapor Injection on Refrigerant Cycle Using Piston Technology
Colmek, Sophie; Goderneaux, Laurent
2012-01-01
Gas vapor injection on refrigerant cycle is always used with Scroll, Rotary or others compressors technology to improve efficiency of the system at low and high ambient temperatures. Probably this kind of compressor is more adapted than the piston technology owing to their mechanical system. In this paper, we present the challenge of vapor injection realized on piston technology compressor range non for improving the cooling capacity of the system but to maintain the compressor temperature in...
Ensuring Steady Operation of Free-Piston Generator
Pavel Nemecek
2006-01-01
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.
The Adiabatic Piston and the Second Law of Thermodynamics
Crosignani, B; Conti, C
2002-01-01
A detailed analysis of the adiabatic-piston problem reveals peculiar dynamical features that challenge the general belief that isolated systems necessarily reach a static equilibrium state. In particular, the fact that the piston behaves like a perpetuum mobile, i.e., it never stops but keeps wandering, undergoing sizable oscillations, around the position corresponding to maximum entropy, has remarkable implications on the entropy variations of the system and on the validity of the second law when dealing with systems of mesoscopic dimensions.
Structural design of Stirling engine with free pistons
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.
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)
Method Evaluating the Durability of Aircraft Piston Engines
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 ...
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.
The Adiabatic Piston and the Second Law of Thermodynamics
Crosignani, B.; Di Porto, P.; de Conti, C.
2002-01-01
A detailed analysis of the adiabatic-piston problem reveals peculiar dynamical features that challenge the general belief that isolated systems necessarily reach a static equilibrium state. In particular, the fact that the piston behaves like a perpetuum mobile, i.e., it never stops but keeps wandering, undergoing sizable oscillations, around the position corresponding to maximum entropy, has remarkable implications on the entropy variations of the system and on the validity of the second law...
Design and Analysis of Piston Design for 4 Stroke Hero Bike Engine
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 ...
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.
Electromagnetic liquid pistons for capillarity-based pumping.
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. PMID:21127823
Comparing the Volumes of Rectangular Prisms
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…
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.
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.
The bending of rectangular weakened by a vertical crack
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.
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.
Mobile hydraulic power supply. Liquid piston Stirling engine pump
Energy Technology Data Exchange (ETDEWEB)
Ven, James D. van de [100 Institute Road, Department of Mechanical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609 (United States)
2009-11-15
Conventional mobile hydraulic power supplies involve numerous kinematic connections and are limited by the efficiency, noise, and emissions of internal combustion engines. The Stirling cycle possesses numerous benefits such as the ability to operate from any heat source, quiet operation, and high theoretical efficiency. The Stirling engine has seen limited success due to poor heat transfer in the working chambers, difficulty sealing low-molecular weight gases at high pressure, and non-ideal piston displacement profiles. As a solution to these limitations, a liquid piston Stirling engine pump is proposed. The liquid pistons conform to irregular volumes, allowing increased heat transfer through geometry features on the interior of the working chambers. Creating near-isothermal operation eliminates the costly external heat exchangers and increases the engine efficiency through decreasing the engine dead space. The liquid pistons provide a positive gas seal and thermal transport to the working chambers. Controlling the flow of the liquid pistons with valves enables matching the ideal Stirling cycle and creates a direct hydraulic power supply. Using liquid hydrogen as a fuel source allows cooling the compression side of the engine before expanded the fuel into a gas and combusting it to heat the expansion side of the engine. Cooling the compression side not only increases the engine power, but also significantly increases the potential thermal efficiency of the engine. A high efficiency Stirling engine makes energy regeneration through reversing the Stirling cycle practical. When used for regeneration, the captured energy can be stored in thermal batteries, such as a molten salt. The liquid piston Stirling engine pump requires further research in numerous areas such as understanding the behavior of the liquid pistons, modeling and optimization of a full engine pump, and careful selection of materials for the extreme operating temperatures. Addressing these obtainable
RWGSCAT - RECTANGULAR WAVEGUIDE JUNCTION SCATTERING PROGRAM
Hoppe, D. J.
1994-01-01
In order to optimize frequency response and determine the tolerances required to meet RF specifications, accurate computer modeling of passive rectangular waveguide components is often required. Many rectangular waveguide components may be represented either exactly or approximately as a number of different size rectangular waveguides which are connected in series. RWGSCAT, Rectangular WaveGuide junction SCATtering program, solves for the scattering properties of a waveguide device. This device must consist of a number of rectangular waveguide sections of different cross sectional area which are connected in series. Devices which fall into this category include step transformers, filters, and smooth or corrugated rectangular horns. RWGSCAT will model such devices and accurately predict the reflection and transmission characteristics, taking into account higher order (other than dominant TE 10) mode excitation if it occurs, as well as multiple reflections and stored energy at each discontinuity. For devices which are large with respect to the wavelength of operation, the characteristics of the device may be required for computing a higher order mode or a number of higher order modes exciting the device. Such interactions can be represented by defining a scattering matrix for each discontinuity in the device, and then cascading the individual scattering matrices in order to determine the scattering matrix for the overall device. The individual matrices are obtained using the mode matching method. RWGSCAT is written in FORTRAN 77 for IBM PC series and compatible computers running MS-DOS. It has been successfully compiled and implemented using Lahey FORTRAN 77 under MS-DOS. A sample MS-DOS executable is provided on the distribution medium. It requires 377K of RAM for execution. Sample input data is also provided on the distribution medium. The standard distribution medium for this program is one 5.25 inch 360K MS-DOS format diskette. The contents of the diskette are
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.
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
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.
Magnetic bearings for free-piston Stirling engines
Curwen, P. W.; Fleming, D. P.; Rao, D. K.; Wilson, D. S.
1992-08-01
The feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery currently being developed for long-term space missions are assessed. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) which currently uses hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Active magnetic bearings of the attractive electromagnetic type are feasible for the RSSPC power piston. Magnetic support of the displacer assembly would require unacceptable changes to the design of the current RSSPC. However, magnetic suspension of both displacer and power piston is feasible for a relative-displacer version of the RSSPC. Magnetic suspension of the RSSPC power piston can potentially increase overall efficiency by 0.5 to 1 percent (0.1 to 0.3 efficiency points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems. These advantages, however, are accompanied by a 5 percent increase in specific mass of the RSSPC.
MACAO-VLTI piston issue: achieving the interferometry requirements
Ivanescu, Liviu; Arsenault, Robin; Fedrigo, Enrico; Kasper, Markus E.; Oberti, Sylvain; Paufique, Jerome; Stroebele, Stefan
2004-10-01
MACAO-VLTI is a set of four adaptive optics systems dedicated to interferometry with the ESO 8 meter telescopes in Paranal, Chile. One of the most important requirements for the MACAO-VLTI is to keep the piston variations of the bimorph deformable mirror below 25 nm RMS in a time window of 48 msec. For this purpose, a piston removal algorithm has been developed, that uses a pre-calibrated set of voltages to compensate the natural piston of each influence function. This pre-calibration constitutes a critical laboratory measurement of the influence functions. Using Hadamard matrices, a (64 x 64) Shack-Hartman sensor and a capacitive sensor located at the center of the mirror (back-side), an accuracy better than 1% has been reached to characterize them. Various configurations were investigated to minimize the dynamical residual piston: the control matrix, the loop speed and the loop gain. Particular attention was paid to the influence functions non-linearities. An original indirect method was developed to measure the residual piston in real-time. We present here the methods and results obtained so far.
Anisotropic rectangular metric for polygonal surface remeshing
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.
Rectangular Pulsed Laser-Electromagnetic Hybrid Accelerator
International Nuclear Information System (INIS)
Experimental investigation of impulse-bit and propellant consumption rate, or mass shot, per single pulse discharge was conducted to characterize the thrust performance of the rectangular laser-electromagnetic hybrid acceleration thruster with various propellant materials. From the result, alumina propellant showed significantly superior performance. The largest values of the measured impulse-bit, specific impulse and thrust efficiency were 49 μNsec, 6,200 sec and 22%, respectively.
RE-1000 free-piston Stirling engine update
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.
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.
Flow resistance of hydraulic cylinder piston ring seal structure
International Nuclear Information System (INIS)
According to the control rod hydraulic drive mechanism (CRHDM) and the characteristics of its hydraulic cylinder seal structure, the leaking ways of the hydraulic cylinder piston ring seal were analysed, its theoretical calculation model was built and its flow resistance formula based on the calculation model of differential pressure at the hydraulic cylinder piston ring seal was deduced. By analyzing the results of the CRHDM single cylinder experiment, constants in the formula of the flow resistance were obtained. Under the experimental condition, results from the formula and the experiment tally with each other. The formula and analysis would be helpful for the theoretical analysis and engineering design of the hydraulic cylinder piston ring seal structure. (author)
Hot piston ring/cylinder liner materials - Selection and evaluation
Sliney, Harold E.
1988-01-01
A materials testing program to determine whether automotive Stirling engine efficiency can be improved by locating 'hot piston rings' near the top of the pistons is described. Candidate materials were screened theoretically and experimentally by friction and wear tests. Based on the test results, a cobalt-based alloy, Stellite 6B, was chosen for the piston rings and PS200, which consists of a metal-bonded chromium carbide matrix with dispersed solid lubricants, was chosen as the cylinder coating. Tests of a modified engine and a baseline engine showed that the hot ring did reduce specific fuel consumption by up to 7 percent for some operating conditions and averaged about three percent for all conditions evaluated. Related applications of high-temperature coatings for shaft seals and as backup lubricants for gas bearings are also described.
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)
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.
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.
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.
Symmetry of the adiabatic condition in the piston problem
International Nuclear Information System (INIS)
This study addresses a controversial issue in the adiabatic piston problem, namely that of the piston being adiabatic when it is fixed but no longer so when it can move freely. It is shown that this apparent contradiction arises from the usual definition of adiabatic condition. The issue is addressed here by requiring the adiabatic condition to be compatible with the invariance of total entropy under a system-surroundings interchange. This paper also strengthens some recently published ideas concerning the concepts of heat and dissipative work, and is primarily intended for teachers and graduate students, as well as for all who are interested in this fascinating problem.
Redesign of a Shock Absorber Piston Using Sintering
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...
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.
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....
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.
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.
Simulation of a Martini Displacer Free Piston Stirling Engine for Electric Power Generation
Pascal Stouffs; Nasser Seraj Mehdizadeh
2000-01-01
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 element...
STRESS ANALYSIS OF IC ENGINE PISTON FOR DIFFERENT MATERIAL AND PRESSURE LOAD USING FEA
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...
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.
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...
Experimental Investigation of a Rectangular Airlift Pump
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 ...
Conformal boundary state for the rectangular geometry
International Nuclear Information System (INIS)
We discuss conformal field theories (CFTs) in rectangular geometries, and develop a formalism that involves a conformal boundary state for the 1+1d open system. We focus on the case of homogeneous boundary conditions (no insertion of a boundary condition changing operator), for which we derive an explicit expression of the associated boundary state, valid for any arbitrary CFT. We check the validity of our solution, comparing it with known results for partition functions, numerical simulations of lattice discretizations, and coherent state expressions for free theories.
Shear Behavior of Rectangular Composite Lattice Structures
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...
Recharge from rectangular areas to finite aquifers
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.
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 ...
Experiments on the WavePiston, Wave Energy Converter
DEFF Research Database (Denmark)
Angelelli, E.; Zanuttigh, B.; Kofoed, Jens Peter;
2011-01-01
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...
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.
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.
A comparative reliability analysis of free-piston Stirling machines
Schreiber, Jeffrey G.
2001-02-01
A free-piston Stirling power convertor is being developed for use in an advanced radioisotope power system to provide electric power for NASA deep space missions. These missions are typically long lived, lasting for up to 14 years. The Department of Energy (DOE) is responsible for providing the radioisotope power system for the NASA missions, and has managed the development of the free-piston power convertor for this application. The NASA Glenn Research Center has been involved in the development of Stirling power conversion technology for over 25 years and is currently providing support to DOE. Due to the nature of the potential missions, long life and high reliability are important features for the power system. Substantial resources have been spent on the development of long life Stirling cryocoolers for space applications. As a very general statement, free-piston Stirling power convertors have many features in common with free-piston Stirling cryocoolers, however there are also significant differences. For example, designs exist for both power convertors and cryocoolers that use the flexure bearing support system to provide noncontacting operation of the close-clearance moving parts. This technology and the operating experience derived from one application may be readily applied to the other application. This similarity does not pertain in the case of outgassing and contamination. In the cryocooler, the contaminants normally condense in the critical heat exchangers and foul the performance. In the Stirling power convertor just the opposite is true as contaminants condense on non-critical surfaces. A methodology was recently published that provides a relative comparison of reliability, and is applicable to systems. The methodology has been applied to compare the reliability of a Stirling cryocooler relative to that of a free-piston Stirling power convertor. The reliability analysis indicates that the power convertor should be able to have superior reliability
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.
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...
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.
Investigation of Starting Behaviour of a Free-piston Linear Generator
Aziz, A. Rashid A.; Abdulwehab A. Ibrahim; Ezrann Zharif Zainal Abidin; Saiful A. Zulkifli
2012-01-01
A linear engine coupled to a permanent-magnet assembly becomes a linear generator engine (LG) which can produce electrical power. Its working principle is based on the free-piston two-stroke engine. The main difference between the LG and a conventional crank-slider engine is that the LG has only one moving part which is the piston-rod assembly (translator). The piston-rod assembly consists of two pistons and a rod, with one piston connected to each end of the rod and a magnet assembly a...
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.
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.
Coupled dynamic-multidimensional modelling of free-piston engine combustion
International Nuclear Information System (INIS)
Free-piston engines are under investigation by a number of research groups worldwide, as an alternative to conventional technology in applications such as electric and hydraulic power generation. The piston dynamics of the free-piston engine differ significantly from those of conventional engines, and this may influence in-cylinder gas motion, combustion and emissions formation. Due to the complex interaction between mechanics and thermodynamics, the modelling of free-piston engines is not straight-forward. This paper presents a novel approach to the modelling of free-piston engines through the introduction of solution-dependent mesh motion in an engine CFD code. The particular features of free-piston engines are discussed, and the model for engine dynamics implemented in the CFD code is described. Finally, the coupled solver is demonstrated through the modelling of a spark ignited free-piston engine generator
Piston surface heat transfer during combustion in large marine diesel engines
DEFF Research Database (Denmark)
Jensen, Michael Vincent; Walther, Jens Honore
2010-01-01
In the design process of large marine diesel engines information on the maximum heat load on the piston surface experienced during the engine cycle is an important parameter. The peak heat load occurs during combustion when hot combustion products impinge on the piston surface. Although the maximum...... heat load is only present for a short time of the total engine cycle, it is a severe thermal load on the piston surface. At the same time, cooling of the piston crown is generally more complicated than cooling of the other components of the combustion chamber. This can occasionally cause problems...... with burning off piston surface material. In this work the peak heat load on the piston surface of large marine diesel engines during combustion was investigated. Measurements of the instantaneous surface temperature and surface heat flux on pistons in large marine engines are difficult due to expensive...
Liner surface improvements for low friction piston ring packs
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
Nonattacking Queens in a Rectangular Strip
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.
Physics from Angular Projection of Rectangular Grids
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...
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.
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...
Obtaining S values for rectangular--solid tumors inside rectangular--solid host organs
International Nuclear Information System (INIS)
A method is described for obtaining S values between a tumor and its host organ for use with the MIRD formalism. It applies the point-source specific absorbed fractions for an infinite water medium, tabulated by Berger, to a rectangular solid of arbitrary dimensions which contains a rectangular tumor of arbitrary dimensions. Contributions from pairs of source and target volume elements are summed for the S values between the tumor and itself, between the remaining healthy host organ and itself, and between the tumor and the remaining healthy host organ, with the reciprocity theorem assumed for the last. This method labeled MTUMOR, is interfaced with the widely used MIRDOSE program which incorporates the MIRD formalism. An example is calculated
Externally heated valve engine a new approach to piston engines
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...
Palm Power Free-Piston Stirling Engine Control Electronics
Keiter, Douglas E.; Holliday, Ezekiel
2007-01-01
A prototype 35We, JP-8 fueled, soldier-wearable power system for the DARPA Palm Power program has been developed and tested by Sunpower. A hermetically-sealed 42We Sunpower Free-Piston Stirling Engine (FPSE) with integral linear alternator is the prime mover for this system. To maximize system efficiency over a broad range of output power, a non-dissipative, highly efficient electronic control system which modulates engine output power by varying piston stroke and converts the AC output voltage of the FPSE into 28Vdc for the Palm Power end user, has been designed and demonstrated as an integral component of the Palm Power system. This paper reviews the current status and progress made in developing the control electronics for the Palm Power system, in addition to describing the operation and demonstrated performance of the engine controller in the context of the current JP-8 fueled Palm Power system.
NEW DESIGN OF PISTON RODS SEALING UNIT OF STERLING ENGINE
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...
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.
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.
β Style Free-Piston Stirling Engine Control System Research
Xu Jian; Zhang Yongsheng
2016-01-01
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 effectiven...
Analysis of gas-piston engine`s outlook
Безюков, Олег Константинович; Жуков, Владимир Анатольевич; Ященко, О. И.
2014-01-01
Comparative characteristics of different kinds of gas fuel for internal combustion engines are given in the article. Experience of use gas-fuel for engines was analysed. Prospects of widening gas-piston engines’ employment into conditions of rising ecological requirements for power plant of means of transport are shown. The appraisal of influence of gas-fuel’s using by index of working process, economical and ecological characteristics of engines is presented. Problems, which must be solved f...
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.
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.
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.
Aluminium matrix heterophase composites for air compressor pistons
Directory of Open Access Journals (Sweden)
M.Dyzia
2011-04-01
Full Text Available The article presents the results of surface test of composite shaped in the permanent mould casting process. As part of the research anddevelopment project realized in the Department of Materials Technology at the Silesian University of Technology, a pilot plant scale stand was built to manufacture of more than 50 kg suspensions in a single technological cycle. Made in industrial conditions castings to form in the five inner core mould mounted in GM110 permanent mould casting machine confirmed the possibility of the shaping the composite pistons. Castings made from composite suspension AlSi7Mg/SiC and AlSi7Mg/SiC + Cg according to the technology procedure were classified as correct and devoted to the proper machining forming working surfaces of the piston to the air compressor. Comparative tests were performed for the casting of unreinforced AlSi7Mg alloy and composite castings. To assess the ability to fill the mold cavity and the accuracy of mapping used in contour shape FRT analysis of the distance between the grooves on the surface of the piston skirt. Studies have confirmed the differences in the fluidity of alloy matrix and composites suspensions. The difference in the accuracy of the dimensional mapping mould does not disqualify of composite materials, all castings are classified as correct and used for machining.
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.
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.)
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.
Computation of power and astigmatism of rectangular pupil wavefront
International Nuclear Information System (INIS)
Least square method is used to fit power and astigmatism of rectangular pupil wavefront data, which avoids data interpolation of the blank area in circular domain. In the experiments, the maximal difference of power and astigmatism of circular domain data between commercial software and our method is less than 0.005 wavelength, which proves the proposed method's feasibility. For rectangular pupil wavefront data, the differences of astigmatism increase as the rectangle element's length-width ratio increases, Therefore the proposed method is more applicable for rectangular pupil wavefront calculation. (authors)
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.
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.
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.
The hydrodynamic focusing effect inside rectangular microchannels
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.
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.
Perceptual guidelines for creating rectangular treemaps.
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
Rectangular Diamond-Lined Accelerator Structure
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 ...
Epidemic Spreading in Random Rectangular Networks
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...
Rizzo, Giuseppe; Bonanno, Antonino; Massarotti, Giorgio Paolo; Pastorello, Luca; Raimondo, Mariarosa; Veronesi, Federico; Blosi, Magda
2016-01-01
Axial piston pumps and motors are widely used in heavy-duty applications and play a fundamental role in hydrostatic and power split drives. The mechanical power losses in hydraulic piston pumps come from the friction between parts in relative motion. The improvement, albeit marginal, in overall efficiency of these components may significantly impact the global efficiency of the machine. The friction between slipper and swash plate is a functional key in an axial piston pump, especially when t...
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.
One-dimensional Brownian motion in hard rods: The adiabatic piston problem
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.
Assessment of 25 kW free-piston Stirling technology alternatives for solar applications
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.
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...
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
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.
A Rectangular Planar Spiral Antenna for GIS Partial Discharge Detection
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...
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.
Design of Rectangular Microstrip Antenna with Metamaterial for Increased Bandwidth
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...
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.
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.
A liquid helium piston pump with a superconducting drive
International Nuclear Information System (INIS)
This chapter describes a bellows pump where the driving force is achieved by an arrangement of three superconducting coils. The pump was designed for use in the supercritical helium flow circuit of the LCT-conductor test facility. The main advantage of the superconducting drive, compared to conventional pumps with external drive, is the compact design. Force transferring parts between 4.2 K and room temperature are not necessary. The pump was tested in a closed loop arrangement. The superconducting drive for a piston pump consists of a moving coil in a constant background field. Other coil configurations and the upscaling of the pump design are discussed
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.
Piston cylinder cell for high pressure ultrasonic pulse echo measurements.
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
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
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.
Passive Control of Supersonic Rectangular Jets through Boundary Layer Swirl
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.
Vacuum Stress and Closed Paths in Rectangles, Pistons, and Pistols
Fulling, S A; Kirsten, K; Liu, Z H; Milton, K A
2008-01-01
Rectangular cavities are solvable models that nevertheless touch on many of the controversial or mysterious aspects of the vacuum energy of quantum fields. This paper is a thorough study of the two-dimensional scalar field in a rectangle by the method of images, or closed classical (or optical) paths, which is exact in this case. For each point r and each specularly reflecting path beginning and ending at r, we provide formulas for all components of the stress tensor T_{\\mu\
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....
The low-cost and precise piston gas pressure regulator
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.
π0 Reconstruction using the Muon Piston Calorimeter Extension
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).
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.
Casimir Force on a Piston in Randall-Sundrum Models
International Nuclear Information System (INIS)
The Casimir effect of a piston for massless scalar fields which satisfy Dirichlet boundary conditions in the context of five-dimensional Randall-Sundrum models is studied. In these scenarios we derive and calculate the expression for the Casimir force on the piston. We also discuss the Casimir force in the limit that one outer plate is moved to the remote place to show that the nature of the reduced force between the parallel plates left. In the Randall-Sundrum model involving two branes the two plates attract each other when they locate very closely, but the reduced Casimir force turns to be repulsive as the plates separation is not extremely tiny, which is against the experimental phenomena, meaning that the RSI model can not be acceptable. In the case of one brane model the shape of the reduced Casimir force is similar to that of the standard two-parallel-system in the four-dimensional flat spacetimes while the sign of force remains negative. (physics of elementary particles and fields)
Imaging sensor for monitoring of the piston mechanism in cylindrical valves
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.
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.
Computer Aided Design of Kaplan Turbine Piston with SolidWorks
Camelia Jianu
2010-01-01
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.
Energy efficient piston configuration for effective air motion – A CFD study
International Nuclear Information System (INIS)
Highlights: ► All piston crown show similar flow pattern for experimental and simulated studies. ► Piston position plays a predominant role in the air pattern inside the cylinder. ► The flat bowl piston shows higher TKE compared to all other piston crown shape. ► The turbulence intensity and length scale are higher for flat bowl piston. ► The quantitative error between the CFD and PIV analysis is about 5%. -- Abstract: Air motion inside the cylinder is very important from the point of view of energy efficiency. In this direction, piston configuration plays a very crucial role. This study is concerned with the CFD analysis of in-cylinder air motion coupled with the comparison of predicted results with the experimental results available in the literature. Four configurations viz., flat, inclined, centre bowl and inclined offset bowl pistons have been studied. For numerical analysis STAR-CD CFD software has been used. Experimental results available in the literature for comparison are obtained by PIV measurements. From this study, it is concluded that a centre bowl on flat piston is found to be the best from the point of view of tumble ratio, turbulent kinetic energy, turbulent intensity and turbulent length scale which play very important role in imparting proper air motion, there by increasing the energy efficiency of the engine.
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.
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.
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
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.
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.
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.
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?
Counter-current flow limitation in thin rectangular channels
International Nuclear Information System (INIS)
The phenomenon of counter-current flow limitation (CCFL) in thin rectangular channels is important in determining the heat removal capability of research reactors which use plate-type fuel elements similar to the MTR design. An analytical expression for predicting CCFL in narrow rectangular channels was derived from the momentum equations for the liquid and gas phase. The model assumes that the liquid downflow is in the form of a film along the narrower side walls of the channel, while the gas flow occupies the wide span of the rectangular channel. The average thickness of liquid film is related to the rate of gas flow through a stability criterion for the liquid film. The CCFL correlation agrees with air/water data taken at relatively high gas velocities. Depending on the magnitude of the dimensionless channel width W*, the new CCFL correlation approaches zero liquid penetration either in the form of a Wallis correlation or in terms of a Kutateladze number. The new correlation indicates that for a thin rectangular channel, the constant C in the Wallis flooding correlation depends on the aspect ratio of the channel. The approach to the appropriate asymptotic solutions also justifies the use of twice the wide span as the correct length scale for thin rectangular channels. 14 refs., 6 figs
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
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.
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.
Integrated two-cylinder liquid piston Stirling engine
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.
CFD Modeling of Free-Piston Stirling Engines
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.
Kinetic resistance of hydraulic cylinder piston ring seal structure
International Nuclear Information System (INIS)
According to the step motion of single cylinder for Control Rod Hydraulic Drive Mechanism (CRHDM) and the characteristics of the hydraulic cylinder piston ring seal structure, the source of kinetic resistance during step motion process was analyzed, the theoretical model of the dynamic step motion process was built and the value of kinetic resistance based on the results of the control rod hydraulic drive mechanism single cylinder experiment was deduced. By analyzing the relationship between kinetic resistance and the dynamic parameters of the step motion process including the pressure and the velocity of the inner cylinder, calculation model of the kinetic resistance during the step motion process was obtained. The displacement curve inferred from this model agrees with the experimental data. This model would be helpful for the dynamic simulation of the step motion process and the stress analysis of the control rod hydraulic drive mechanism. (authors)
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.
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...... objective measures are considered here, in particular Clarity (C80), Strength (G) and Early Lateral Energy Fraction (LF80). Results from simulations have been compared with regression models created based on real hall measurements. In general, simulated results of C80 and G are found to be in good agreement...... with regression models. Divergences are found in LF80 behaviour; these have been associated with influence of proportions of rectangular halls. Updated formula for predicting of LF80 in rectangular halls has been proposed, which takes into the account both width and length of hall....
Rectangular superpolynomials for the figure-eight knot
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 ...
Dirichlet problem for equations of mixed type in rectangular domain
Basirovich, Sabitov Kamil
2015-11-01
In recent years, developed an interest in the study of boundary value problems for equations of mixed type in rectangular areas. This method proved theorems on the unique solubility and stability of the Dirichlet problem [1 - 3] under certain restrictions on the aspect ratio of the rectangular region of the hyperbolic. In this paper, for the mixed type equation with the Lavrent'ev-Bitsadze Dirichlet problem in a rectangular area. The criterion of uniqueness of the solution of the Dirichlet problem. The solution is built as the sum of the Fourier series. In justifying the convergence of a problem of small denominators regarding the relationship of the parties of the hyperbolic part of the rectangle. In connection with this evaluation are set to secede from scratch small denominator corresponding to the asymptotic behavior of rational and irrational values of the ratio, which allowed to substantiate the convergence of the series constructed in the class of regular solutions.
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.
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.
H And U-Slotted Rectangular Microstrip Patch Antenna
Directory of Open Access Journals (Sweden)
Bharat Rochani
2012-09-01
Full Text Available The microstrip patch is one of the most preferred antenna structures for low cost and compact design for wireless system. Dual and triple band antennas are of a relative interest since they can support multiple communication systems. In this paper we present designs of compact small size microstrip antennas suitable for dual and triple band operations. By loading properly arranged slots on a rectangular microstrip patch, dual and triple frequencies and broadband operations of a single feed rectangular patch is achieved. Dual and triple frequency operation is achieved by loading U and H slots in rectangular patch. The impedance bandwidth of 150MHz, 1.26GHz band for U slot and 154MHz, 484MHz, 396MHz for H slot is obtained in the proposed designs
Hybrid method for vibration analysis of rectangular plates
International Nuclear Information System (INIS)
This paper presents a semi-analytical approach for the dynamic analysis of rectangular plates. The mathematical model is developed using a hybrid combination of the finite element method and Sanders' shell theory. The in-plane, membrane displacement components are modelled by bilinear polynomials and the out-of-plane, normal to mid-surface displacement component is modelled by an exponential function that represents a general form of the exact solution of the equations of motion. The displacement functions are obtained by exact solution of the equilibrium equations of the rectangular plates. The mass and stiffness matrices are then determined by exact analytical integration to establish the plate's dynamic equations. The effect of various geometrical parameters and boundary conditions on the dynamic responses of the rectangular plates has been explored in this work. The results are in satisfactory agreement with those of experiments and other theories
Accomplishments in free-piston stirling tests at NASA GRC
International Nuclear Information System (INIS)
A power system based on the Stirling Radioisotope Generator (SRG) has been identified for potential use on deep space missions, as well as for Mars rovers that may benefit from extended operation. The Department of Energy (DOE) has responsibility for developing the generator and the NASA Glenn Research Center (GRC) is supporting DOE in this effort. The generator is based on a free-piston Stirling power convertor that has been developed by the Stirling Technology Company (STC) under contract to DOE. The generator would be used as a high-efficiency alternative to the Radioisotope Thermoelectric Generators (RTGs) that have been used on many previous missions. The increased efficiency leads to a factor of 3 to 4 reduction in the inventory of plutonium required to heat the generator. GRC has been involved in the development of Stirling power conversion technology for over 25 years. The support provided to this project by GRC has many facets and draws upon the lab's scientists and engineers that have gained experience in applying their skills to the previous Stirling projects. This has created a staff with an understanding of the subtleties involved in applying their expertise to Stirling systems. Areas include materials, structures, tribology, controls, electromagnetic interference, permanent magnets, alternator analysis, structural dynamics, and cycle performance. One of the key areas of support to the project is in the performance testing of the free-piston Stirling convertors. Since these power convertors are the smallest, lowest power Stirling machines that have been tested at GRC, a new laboratory was equipped for this project. Procedures and test plans have been created, instrumentation and data systems developed, and Stirling convertors have been tested. This paper will describe the GRC test facility, the test procedures that are used, present some of the test results and outline plans for the future
5-kWe Free-piston Stirling Engine Convertor
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
A Novel Dual-Band Circularly Polarized Rectangular Slot Antenna
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...
Internal combustion engine with a central crankshaft and integral tandem annular pistons
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.
Thermoacoustic model of a modified free piston Stirling engine with a thermal buffer tube
International Nuclear Information System (INIS)
This article presents a modified free-piston Stirling heat engine configuration in which a thermal buffer tube is added to sandwich between the hot and cold heat exchangers. Such a modified configuration may lead to an easier fabrication and lighter weight of a free piston. To analyze the thermodynamic performance of the modified free piston Stirling heat engine, thermoacoustic theory is used. In the thermoacoustic modelling, the regenerator, the free piston, and the thermal buffer tube are given at first. Then, based on linear thermoacoustic network theory, the thermal and thermodynamic networks are presented to characterize acoustic pressure and volume flow rate distributions at different interfaces, and the global performance such as the power output, the heat input and the thermal efficiency. A free piston Stirling heat engine with several hundreds of watts mechanical power output is selected as an example. The typical operating and structure parameters are as follows: frequency around 50 Hz, mean pressure around 3.0 MPa, and a diameter of free piston around 50 mm. From the analysis, it was found that the modified free-piston Stirling heat engine has almost the same thermodynamic performance as the original design, which indicates that the modified configuration is worthy to develop in future because of its mechanical simplicity and reliability.
The compound piston: resolution of a thermodynamic controversy by means of kinetic theory
Sands, David; Dunning-Davies, Jeremy
2010-07-01
A numerical model of a hard-sphere fluid on either side of a compound piston shows that damping occurs naturally without invoking extraneous mechanisms such as friction. Inter-particle collisions are identified as being responsible. Whereas only the component of particle momentum in the direction of the piston motion is affected by the collisions with the piston, inter-particle collisions affect the other components of momentum and effectively dissipate the energy of the piston. These ideas are then incorporated into a simpler, one-dimensional numerical model based on kinetic theory in which all the particles have the same initial energy and inter-particle collisions are simulated by randomly adjusting the energy distribution. Varying the rate of energy redistribution alters the rate of decay of the piston motion, but we find the net work done to be dependent only on the starting conditions and quite independent of the detailed motion. This allows the consequences for thermodynamics of this intrinsic dissipation process to be investigated. We find that the adiabatic compound piston is irreversible, with the net work done being given by the product of the final pressure and the volume change. This finding is supported mathematically and we propose a simple method for determining the final piston position.
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.
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.
ANALYSIS OF A SYSTEM MODELLING THE MOTION OF A PISTON IN A VISCOUS GAS
Maity, Debayan; Takahashi, Takéo; Tucsnak, Marius
2016-01-01
We study a free boundary problem modelling the motion of a piston in a viscous gas. The gas-piston system fills a cylinder with fixed extremities, which possibly allow gas from the exterior to penetrate inside the cylinder. The gas is modeled by the 1D compressible Navier-Stokes system and the piston motion is described by the second Newton's law. We prove the existence and uniqueness of global in time strong solutions. The main novelty brought in by our results is that they include the case ...
Dynamics of a Massive Piston in an Ideal Gas: Oscillatory Motion and Approach to Equilibrium
Chernov, N.; Lebowitz, J. L.
2002-01-01
We study numerically and theoretically (on a heuristic level) the time evolution of a gas confined to a cube of size $L^3$ divided into two parts by a piston with mass $M_L \\sim L^2$ which can only move in the $x$-direction. Starting with a uniform ``double-peaked'' (non Maxwellian) distribution of the gas and a stationary piston, we find that (a) after an initial quiescent period the system becomes unstable and the piston performs a damped oscillatory motion, and (b) there is a thermalizatio...
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; Felter, Christian; Vølund, Anders
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...... 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...
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...... 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...
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....
Josephson junctions in thin and narrow rectangular superconducting strips
Clem, John R.
2010-01-01
I consider a Josephson junction crossing the middle of a thin rectangular superconducting strip of length L and width W subjected to a perpendicular magnetic induction B. I calculate the spatial dependence of the gauge-invariant phase difference across the junction and the resulting B dependence of the critical current Ic(B).
Rectangular matrix models and combinatorics of colored graphs
International Nuclear Information System (INIS)
We present applications of rectangular matrix models to various combinatorial problems, among which the enumeration of face-bicolored graphs with prescribed vertex degrees, and vertex-tricolored triangulations. We also mention possible applications to interaction-round-a-face and hard-particle statistical models defined on random lattices
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...
Josephson junctions in thin and narrow rectangular superconducting strips
International Nuclear Information System (INIS)
I consider a Josephson junction crossing the middle of a thin rectangular superconducting strip of length L and width W subjected to a perpendicular magnetic induction B. I calculate the spatial dependence of the gauge-invariant phase difference across the junction and the resulting B dependence of the critical current Ic(B).
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.
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.
Experimental study of dryout heat transfer in rectangular channel
International Nuclear Information System (INIS)
The experiment of dryout heat transfer in rectangular channel has been carried out on the basic experimental loop of flow and heat transfer at NPIC. The results of the experimental study of thermal-hydraulic parameters on characteristics of dryout heat transfer in rectangular channel show that: (1) The dryout heat flux, wall temperature and heat transfer coefficient decrease, while the dryout quality increases with the increase of inlet quality; (2) The dryout heat flux, wall temperature and heat transfer coefficient increase, while the dryout quality decreases with the increase of mass flow velocity; (3) The dryout heat flux, quality, wall temperature and heat transfer coefficient increase with the increase of system pressure. Comparing the experimental data with empirical correlations, it finds out that these correlations are appropriate for the situations of middle-high pressure and low-middle mass flow velocity, and deviate seriously in low pressure and high mass flow velocity cases. Based on the Gutajellade correlation, and considering the effects of the dimension of rectangular channel and inlet enthalpy on heat transfer, a new correlation for dryout in rectangular channel is developed, which correlates the experimental data quite well. (authors)
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 is......-uniformity of the internal field, especially for non-constant temperature distributions and composite magnetic materials....
Internal flow characteristics of a rectangular ramjet air intake
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
Modal analysis applied to circular, rectangular, and coaxial waveguides
Hoppe, D. J.
1988-01-01
Recent developments in the analysis of various waveguide components and feedhorns using Modal Analysis (Mode Matching Method) are summarized. A brief description of the theory is presented, and the important features of the method are pointed out. Specific examples in circular, rectangular, and coaxial waveguides are included, with comparisons between the theory and experimental measurements. Extensions to the methods are described.
Numerical simulation of small section rectangular tube in parallel welding
Institute of Scientific and Technical Information of China (English)
无
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.
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.
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.
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)
STUDY OF ELABORATION OF CONSTRUCTION CRANKSHAFT PISTON OF AUTOMOBILE PNEUMATIC ENGINE
А. Voronkov
2013-01-01
Expound are the results of study of elaration of construction of crankshaft 4-cylinder V-evocative piston pneumatic engine, which is made by conversion of serial internal-combustion engine 4Ч 7,6x6,6.
Directory of Open Access Journals (Sweden)
Wu Shenqing
2010-11-01
Full Text Available The preparation and properties of ceramic short fiber reinforced Al-Si alloy matrix composite and it’s application on the piston for internal combustion engines are presented. Alumina or aluminosilicate fibers reinforced Al-Si alloy matrix composite has more excellent synthetical properties at elevated temperature than the matrix alloys. A partially reinforced Al-Si alloy matrix composite piston produced by squeeze casting technique has a firm interface between reinforced and unreinforced areas, low reject rate and good technical tolerance. As a new kind of piston material, it has been used for mass production of about 400,000 pieces of automobile engines piston. China has become one of a few countries in which aluminum alloy matrix composite materials have been used in automobile industry and attained industrialization.
High Specific Power Multiple-Cylinder Alpha Free-Piston Stirling Engine Project
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...
Review Paper on Application of Variable Displacement Linkage in Radial Piston Pump
Directory of Open Access Journals (Sweden)
Mr. Kekare H.T*
2014-12-01
Full Text Available Radial piston pumps are valve controlled with cylinders in a radial arrangement. The cylinder radials in one, two or several superimposed layers (stars are driven by bearing fitted eccentrically on the drive shaft (piston pressure stroke, then being returned to their idle position by springs (piston intake stroke.The fluid being delivered by the various cylinders is collected via manifolds feeding one joint pressure port. The pump housing shells are loadbearing elements supporting the cylinders and shaft bearings. The pumps run very smoothly as the drive shaft is statically balanced via counter weights. With the exception of the single- and double-cylinder pumps, there is always an uneven number of pistons per cylinder radial, which minimizes any pulse effect on the pump deliver.
A thermodynamic study for the optimization of stable operation of free piston Stirling engines
International Nuclear Information System (INIS)
One of the most novel applications of the Stirling cycle is in the free piston configuration that was initially designed by W. Beale. In free piston Stirling engines (FPSEs), there are no mechanical linkages coupling the pistons or displacers, the motions of the reciprocating components follow the working gas pressure variations. Fillipo de Monte and G. Benvenuto have recently proposed a linearization technique of the dynamic balance equations. The aim of this paper is to predict the thermodynamic conditions for stable operation of FPSEs and their modeling. The equations of the angular velocity are solved analytically in terms of the working gas mass and the displacer-piston phase angle of the machine. Using the criterion of stable engine cyclic steady operation, a mathematically rigorous form is obtained for the main parameters of the engine. Furthermore, for simplicity reasons, thermodynamic magnitudes are obtained using the Schmidt analysis (isothermal model)
SANS study of the precipitates microstructural evolution in Al 4032 car engine pistons
International Nuclear Information System (INIS)
Small angle neutron scattering (SANS) technique has been used to study the microstructural evolution of precipitates in real pistons made from commonly used AlSi12CuNiMg alloy. The experiment was performed on new and worn out piston crowns. SANS curves were measured at five different points (possible critical locations) of both pistons. At the central points of the new sample an isotropic scattering was observed, while in the lateral parts of the piston the scattering became anisotropic, indicating the presence of a manufacturing induced texture. The Al-Mg-Si alloys exhibit mechanical properties, which are highly sensitive to thermal treatments. The operating temperature is usually very close or, in certain parts of the crown, can exceed the ageing temperature. A comparison of the ageing treatment-caused alteration of mechanical properties with the changes of the precipitates structure is reported
SANS study of the precipitates microstructural evolution in Al 4032 car engine pistons
Energy Technology Data Exchange (ETDEWEB)
Rogante, M. [Rogante Engineering Office, NDT, Contrada San Michele, n. 61, P.O. Box 189, 62012 Civitanova Marche (Italy)]. E-mail: engineering@interfree.it; Lebedev, V.T. [Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg (Russian Federation); Nicolaie, F. [Ferrari Gestione Sportiva, Gruppo Metallurgia, Via Ascari, 55/57, 41053 Maranello (Italy); Retfalvi, E. [Research Institute for Solid State Physics and Optics, Budapest, H-1525, POB.49 (Hungary); Rosta, L. [Research Institute for Solid State Physics and Optics, Budapest, H-1525, POB.49 (Hungary)
2005-04-15
Small angle neutron scattering (SANS) technique has been used to study the microstructural evolution of precipitates in real pistons made from commonly used AlSi12CuNiMg alloy. The experiment was performed on new and worn out piston crowns. SANS curves were measured at five different points (possible critical locations) of both pistons. At the central points of the new sample an isotropic scattering was observed, while in the lateral parts of the piston the scattering became anisotropic, indicating the presence of a manufacturing induced texture. The Al-Mg-Si alloys exhibit mechanical properties, which are highly sensitive to thermal treatments. The operating temperature is usually very close or, in certain parts of the crown, can exceed the ageing temperature. A comparison of the ageing treatment-caused alteration of mechanical properties with the changes of the precipitates structure is reported.
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.
Tribological property of TiO2 nanolubricant on piston and cylinder surfaces
International Nuclear Information System (INIS)
In this paper, an arc spray nanofluid synthesis system with complex ultrasonic orthogonal vibration and vortex stirring was proposed and developed for TiO2 nanolubricant, in which TiO2 nanoparticles were of equal roundness and consistent size. In the proposed nanofluid synthesis system, one of the electrodes and ultrasonic vibrator were assembled to form an orthogonal model with another electrode installed inside the vacuum chamber of arc discharge system, with 10 W/30 lubricant serving as the dielectric liquid. The tribological behavior of the lubricant with TiO2 nanoparticles at average particle size 25 nm on the surface of piston ring is compared with that of the lubricant without TiO2 nanoparticles. Experimental results showed that the coefficients of friction between the piston ring and base lubricant was 0.15; between the piston ring and TiO2 nanolubricant was 0.14. Furthermore, the piston ring's wear rates of the base lubricant and TiO2 nanolubricant were 0.0055 and 0.0021, respectively. After operating the piston cylinder for 8 consecutive hours in 15 and 30 days, respectively, the diameter of TiO2 nanoparticles in the lubricant remained 25 nm in average. As observed from the piston ring surface on the 15th and 30th days through scanning electron microscope (SEM), it had less scraping than the piston lubricated without TiO2 nanoparticles. Therefore, a lubricant added with TiO2 nanoparticles can better protect the piston ring surface.
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...
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.
Wu Shenqing; Li Jun
2010-01-01
The preparation and properties of ceramic short fiber reinforced Al-Si alloy matrix composite and it’s application on the piston for internal combustion engines are presented. Alumina or aluminosilicate fibers reinforced Al-Si alloy matrix composite has more excellent synthetical properties at elevated temperature than the matrix alloys. A partially reinforced Al-Si alloy matrix composite piston produced by squeeze casting technique has a firm interface between reinforced and unreinforced are...
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...
Thermomechanical Fatigue Life Prediction for a Marine Diesel Engine Piston considering Ring Dynamics
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...
An investigation of the fluid-structure interaction of piston/cylinder interface
Pelosi, Matteo
The piston/cylinder lubricating interface represents one of the most critical design elements of axial piston machines. Being a pure hydrodynamic bearing, the piston/cylinder interface fulfills simultaneously a bearing and sealing function under oscillating load conditions. Operating in an elastohydrodynamic lubrication regime, it also represents one of the main sources of power loss due to viscous friction and leakage flow. An accurate prediction of the time changing tribological interface characteristics in terms of fluid film thickness, dynamic pressure field, load carrying ability and energy dissipation is necessary to create more efficient interface designs. The aim of this work is to deepen the understanding of the main physical phenomena defining the piston/cylinder fluid film and to discover the impact of surface elastic deformations and heat transfer on the interface behavior. For this purpose, a unique fully coupled multi-body dynamics model has been developed to capture the complex fluid-structure interaction phenomena affecting the non-isothermal fluid film conditions. The model considers the squeeze film effect due to the piston micro-motion and the change in fluid film thickness due to the solid boundaries elastic deformations caused by the fluid film pressure and by the thermal strain. The model has been verified comparing the numerical results with measurements taken on special designed test pumps. The fluid film calculated dynamic pressure and temperature fields have been compared. Further validation has been accomplished comparing piston/cylinder axial viscous friction forces with measured data. The model has been used to study the piston/cylinder interface behavior of an existing axial piston unit operating at high load conditions. Numerical results are presented in this thesis.
Gain Improvement of Dual Band Antenna Based on Complementary Rectangular Split-Ring Resonator
Noelia Ortiz; Francisco Falcone; Mario Sorolla
2012-01-01
A simple and successful dual band patch linear polarized rectangular antenna design is presented. The dual band antenna is designed etching a complementary rectangular split-ring resonator in the patch of a conventional rectangular patch antenna. Furthermore, a parametric study shows the influence of the location of the CSRR particle on the radiation characteristics of the dual band antenna. Going further, a miniaturization of the conventional rectangular patch antenna and an enhancement of t...
A CPW-Fed Rectangular Ring Monopole Antenna for WLAN Applications
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...
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.
Comparison of free-piston Stirling engine model predictions with RE1000 engine test data
Tew, R. C.
1984-01-01
Predictions of a free-piston Stirling engine model are compared with RE1000 engine test data taken at NASA-Lewis Research Center. The model validation and the engine testing are being done under a joint interagency agreement between the Department of Energy's Oak Ridge National Laboratory and NASA-Lewis. A kinematic code developed at Lewis was upgraded to permit simulation of free-piston engine performance; it was further upgraded and modified at Lewis and is currently being validated. The model predicts engine performance by numerical integration of equations for each control volume in the working space. Piston motions are determined by numerical integration of the force balance on each piston or can be specified as Fourier series. In addition, the model Fourier analyzes the various piston forces to permit the construction of phasor force diagrams. The paper compares predicted and experimental values of power and efficiency and shows phasor force diagrams for the RE1000 engine displacer and piston. Further development plans for the model are also discussed.
NOISE IDENTIFICATION FOR HYDRAULIC AXIAL PISTON PUMP BASED ON ARTIFICIAL NEURAL NETWORKS
Institute of Scientific and Technical Information of China (English)
无
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.
Development of an accelerating-piston implosion-driven launcher
Huneault, Justin; Loiseau, Jason; Higgins, Andrew
2013-06-01
The ability to soft-launch projectiles at velocities exceeding 10 km/s is of interest to several scientific fields, including orbital debris impact testing and equation of state research. Current soft-launch technologies have reached a performance plateau below this operating range. The energy and power density of high explosives provides a possible avenue to reach this velocity if used to dynamically compress a light driver gas to significantly higher pressures and temperatures compared to light-gas guns. In the implosion-driven launcher (IDL), linear implosion of a pressurized tube drives a strong shock into the gas ahead of the tube pinch, thereby forming an increasingly long column of compressed gas which can be used to propel a projectile. The McGill IDL has demonstrated the ability to launch a 0.1-g projectile to 9.1 km/s. This study focuses on the implementation of a novel launch cycle wherein the explosively driven pinch is accelerated down the length of the tube in order to maintain a relatively constant projectile base pressure early in the launch cycle. The experimental development of an accelerating driver which utilizes an explosive lens to phase the detonation wave is presented. The design and experimental performance of an accelerating-piston IDL is also discussed.
Differential expansion and rectangular HOMFLY for the figure eight knot
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.
Analytical theory of an unloaded rectangular microstrip patch
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.
Flexural rigidity of biaxially loaded reinforced concrete rectangular column sections
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.
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.
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.
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.
Characterizing octagonal and rectangular fibers for MAROON-X
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.
Lattice Boltzmann Equation On a 2D Rectangular Grid
Bouzidi, MHamed; DHumieres, Dominique; Lallemand, Pierre; Luo, Li-Shi; Bushnell, Dennis M. (Technical Monitor)
2002-01-01
We construct a multi-relaxation lattice Boltzmann model on a two-dimensional rectangular grid. The model is partly inspired by a previous work of Koelman to construct a lattice BGK model on a two-dimensional rectangular grid. The linearized dispersion equation is analyzed to obtain the constraints on the isotropy of the transport coefficients and Galilean invariance for various wave propagations in the model. The linear stability of the model is also studied. The model is numerically tested for three cases: (a) a vortex moving with a constant velocity on a mesh periodic boundary conditions; (b) Poiseuille flow with an arbitrasy inclined angle with respect to the lattice orientation: and (c) a cylinder &symmetrically placed in a channel. The numerical results of these tests are compared with either analytic solutions or the results obtained by other methods. Satisfactory results are obtained for the numerical simulations.
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.
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...
Stability analysis concerning the mining works reinforcement having rectangular profile
International Nuclear Information System (INIS)
The paper deals with the stability of rock masses during underground opening construction. In mining works for ores exploitation with rectangular profile a method combined for reinforcement of rectangular profile was used. The reinforcement system, as part of the roof controls system, helps the rock mass to support itself above the entries improving their stability. The most important task for this is providing confinement. Roof control in this context means the control of the roof strata in the vicinity of the underground opening. Other components of the roof control system are control and standing support. Based on the experimental measurements, at uranium Crucea mine, and a numerical analyzing of state of stress on mining works, the rock bolting support was choose and a combined method was applied
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.
Calculation of the Pipe Work Concentrator Equipped with Rectangular Openings
Directory of Open Access Journals (Sweden)
Ioan Golumbu
2013-09-01
Full Text Available The coefficients of stress concentrators, used for most car bodies are known and published in the literature. There are no data on how big is the effort concentrator for tubes fitted with rectangular openings. The aim of the present work is to make available quickly and economically for the design engineer, values used in design and execution without making complicated simulations with numerical methods.
Acoustic-Gravity Waves Interacting with a Rectangular Trench
Usama Kadri
2014-01-01
A mathematical solution of the two-dimensional linear problem of an acoustic-gravity wave interacting with a rectangular trench, in a compressible ocean, is presented. Expressions for the flow field on both sides of the trench are derived. The dynamic bottom pressure produced by the acoustic-gravity waves on both sides of the trench is measurable, though on the transmission side it decreases with the trench depth. A successful recording of the bottom pressures could assist in the early detect...
Flutter Speed Limits of Cantilever Rectangular and Tapered Plates
Kusay H. Jabir
2007-01-01
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...
Classification of flow patterns in rectangular shallow reservoirs
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...
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.
The hydrodynamic advantages of synchronized swimming in a rectangular pattern.
Daghooghi, Mohsen; Borazjani, Iman
2015-10-01
Fish schooling is a remarkable biological behavior that is thought to provide hydrodynamic advantages. Theoretical models have predicted significant reduction in swimming cost due to two physical mechanisms: vortex hypothesis, which reduces the relative velocity between fish and the flow through the induced velocity of the organized vortex structure of the incoming wake; and the channeling effect, which reduces the relative velocity by enhancing the flow between the swimmers in the direction of swimming. Although experimental observations confirm hydrodynamic advantages, there is still debate regarding the two mechanisms. We provide, to our knowledge, the first three-dimensional simulations at realistic Reynolds numbers to investigate these physical mechanisms. Using large-eddy simulations of self-propelled synchronized swimmers in various rectangular patterns, we find evidence in support of the channeling effect, which enhances the flow velocity between swimmers in the direction of swimming as the lateral distance between swimmers decreases. Our simulations show that the coherent structures, in contrast to the wake of a single swimmer, break down into small, disorganized vortical structures, which have a low chance for constructive vortex interaction. Therefore, the vortex hypothesis, which is relevant for diamond patterns, was not found for rectangular patterns, but needs to be further studied for diamond patterns in the future. Exploiting the channeling mechanism, a fish in a rectangular school swims faster as the lateral distance decreases, while consuming similar amounts of energy. The fish in the rectangular school with the smallest lateral distance (0.3 fish lengths) swims 20% faster than a solitary swimmer while consuming similar amount of energy. PMID:26447493
Initial magnetic field distribution around high rectangular bus bars
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...
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.
FINITE DIFFERENCE MODEL OF A CIRCULAR FIN WITH RECTANGULAR PROFILE
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 ...
Research on applications of rectangular beam in micro laser propulsion
International Nuclear Information System (INIS)
Highlights: • Diode laser bar of 808 nm is introduced into the micro laser propulsion field. • Double base propellant (DBP) coating with BOPP substrate was obtained. • The combination of laser power and energy decides the propulsion performance. • The new rectangular beam prefers to produce higher impulse. - Abstract: Micro laser propulsion is a new technology with brilliant future. In order to reduce the thruster mass and volume further, laser bar is introduced into the micro laser propulsion field. A new kind of 220 × 20 μm rectangular beam of 808 nm was obtained by oval lens compressing the light of diode at fast axes and slow axes. The effect of laser power, energy and coating thickness of double base propellant on propulsion performance was studied. Propulsion performance of double base propellant under static and dynamic mode shows some different characters. Compared to round beam, the new beam prefers to produce higher impulse. Ablation efficiency of DBP shows better performance in short laser duration. The combination of power density and energy density decides the laser propulsion performance. The new rectangular beam is appropriate for millisecond micro-laser propulsion
Evaluation of thermal radiation simulator rectangular pulse characterization methods
International Nuclear Information System (INIS)
This paper discusses the thermal output of an aluminum powder/liquid oxygen Thermal Radiation Simulator (TRS) which is approximated to that of a rectangular pulse. The output varies as a function of time. The rise and fall times are not relatively abrupt. The problem is how to quantify the thermal output of the TRS into terms of rectangular pulse. Within the nuclear weapons effects community, flux, or the transient intensity of thermal radiation energy onto a surface, and fluence, the total energy irradiated on a surface over a given time, are the determining parameters for specifying or evaluating an article's survivability in the thermal environment. Four methods are used to determine the TRS output for these parameters, assuming the output to be a perfect rectangular pulse. It was essential to determine which of the four methods best quantified the thermal output average flux and fluence. The four methods were compared by a computational experiment run on a personal computer. The experiment was a simulation of five actual TRS traces irradiated onto a fictitious aluminum plate
Space Power Free-Piston Stirling Engine Scaling Study
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
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.
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...
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...
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...
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...
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.
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...
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.
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.
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.
Design and novel type of a magnetorheological damper featuring piston bypass hole
International Nuclear Information System (INIS)
This work proposes a novel type of magnetorheological (MR) damper configuration from which an excellent ride comfort can be achieved without using a sophisticated controller scheme. The proposed novel MR damper is featured by piston bypass holes to achieve low slope of the damping force in the pre-yield (low-piston-velocity) region and high magnitude of the damping force in the post-yield (high-piston-velocity) region. A mathematical model for the damping force of the proposed MR damper is formulated followed by the investigation on damping characteristics with respect to several geometrical design parameters such as the number of piston bypass hole, the diameter of the hole, the gap size of the orifice, the orifice length, the diameter of the bobbin, and the height of the coil. After selecting the main design parameters from the simulation results, numerical simulations for the damping force characteristics are conducted with eight design parameter sets to evaluate the significant effect on the damping force performance. The proposed MR dampers are then manufactured with the same design parameter sets and the damping force characteristics are experimentally obtained and compared with the analytical simulation results. It is identified from the parametric investigations that the size and the number of the piston bypass hole are very important on damping force characteristics of the proposed MR damper. (paper)
The Casimir force on a piston in the spacetime with extra compactified dimensions
International Nuclear Information System (INIS)
A Casimir piston for massless scalar fields obeying Dirichlet boundary conditions in high-dimensional spacetimes within the frame of Kaluza-Klein theory is analyzed. We derive and calculate the exact expression for the Casimir force on the piston. We also compute the Casimir force in the limit that one outer plate is moved to the extremely distant place to show that the reduced force is associated with the properties of additional spatial dimensions. The more dimensionality the spacetime has, the stronger the extra-dimension influence is. The Casimir force for the piston in the model including a third plate under the background with extra compactified dimensions always keeps attractive. Further we find that when the limit is taken the Casimir force between one plate and the piston will change to be the same form as the corresponding force for the standard system consisting of two parallel plates in the four-dimensional spacetimes if the ratio of the plate-piston distance and extra dimensions size is large enough
The Casimir force on a piston in the spacetime with extra compactified dimensions
Energy Technology Data Exchange (ETDEWEB)
Cheng Hongbo [Department of Physics, East China University of Science and Technology, Shanghai 200237 (China)], E-mail: hbcheng@public4.sta.net.cn
2008-09-25
A Casimir piston for massless scalar fields obeying Dirichlet boundary conditions in high-dimensional spacetimes within the frame of Kaluza-Klein theory is analyzed. We derive and calculate the exact expression for the Casimir force on the piston. We also compute the Casimir force in the limit that one outer plate is moved to the extremely distant place to show that the reduced force is associated with the properties of additional spatial dimensions. The more dimensionality the spacetime has, the stronger the extra-dimension influence is. The Casimir force for the piston in the model including a third plate under the background with extra compactified dimensions always keeps attractive. Further we find that when the limit is taken the Casimir force between one plate and the piston will change to be the same form as the corresponding force for the standard system consisting of two parallel plates in the four-dimensional spacetimes if the ratio of the plate-piston distance and extra dimensions size is large enough.
The optimal path of piston motion for Otto cycle with linear phenomenological heat transfer law
Institute of Scientific and Technical Information of China (English)
无
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.
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.
Final design of a free-piston hydraulic advanced Stirling conversion system
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.
A piston-rotaxane with two potential stripes: force transitions and yield stresses.
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
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.
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.
Overview of free-piston Stirling engine technology for space power application
International Nuclear Information System (INIS)
An overview is presented of the National Aeronautics and Space Administration (NASA) Lewis Research Center (LeRC) free-piston Stirling engine activities directed toward space-power application. Free-piston Stirling technology is applicable for both solar and nuclear powered systems. As such, the NASA Lewis Research Center serves as the project office to manage the newly initiated SP-100 Advanced Technology program. This program provides the technology push for providing significant component and subsystem options for increased efficiency, reliability and survivability, and power output growth at reduced specific mass. One of the major elements of the program is the development of advanced power conversion of which the Stirling cycle is a viable candidate. Under this program the status of the 25 kWe opposed-piston Space Power Demonstrator Engine (SPDE) is presented. Included in the SPDE discussion are initial differences between predicted and experimental power outputs and power output influenced by variations in regenerators
Lubrication of Piston Rings in Large 2–and 4–stroke Diesel Engines
DEFF Research Database (Denmark)
Felter, Christian Lotz
numerical models implemented as computer programs. The classical Reynolds equation can be used to calculate the pressure distribution in thin films of fluid. In relation to piston ring lubrication it is, however, less straight forward to apply the Reynolds equation since the inlet (and outlet) point of the......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...... lubricated conjunction is not known before hand. In order to overcome this problem, which is the main topic of this work, two different paths are followed. First an equation for the inlet point location is derived under the assumption of steady-state running conditions. Assuming that this limitation is...
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.
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.
Final design of a free-piston hydraulic advanced Stirling conversion system
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.
RWGSCAT/CWGSCAT - RECTANGULAR AND CIRCULAR WAVEGUIDE JUNCTION SCATTERING PACKAGE
Hoppe, D. J.
1994-01-01
Accurate computer modeling of passive circular or rectangular waveguide components is often required during the design phase for optimizing frequency response and/or determining the tolerance required on components in order to meet radio frequency specifications. RWGSCAT/CWGSCAT is capable of modeling both types of waveguide components. The Scattering Matrix Program for Circular Waveguide Junctions, CWGSCAT, computes the scattering matrix for a circular waveguide. This includes a dual mode horn and certain types of corrugated horns. RWGSCAT, Rectangular WaveGuide junction SCATtering program, solves for the scattering properties of a rectangular waveguide device, such as a smooth or corrugated rectangular horn, step transformer, or filter. RWGSCAT and CWGSCAT are also available separately as NPO-19091 and NPO-18708, respectively. Many circular waveguide devices can be represented either exactly or approximately as a series of circular waveguide sections which have a common center. In addition, smooth tapers and horns of arbitrary profile may be approximated by a series of small steps. Devices that may be analyzed in this fashion include a simple waveguide step discontinuity, such as that used in a dual mode horn, a stepped matching section, or a corrugated waveguide section with constant varying slot depth. CWGSCAT will accurately predict the reflection and transmission characteristics of such devices, taking into account higher order mode excitation if it occurs as well as multiple reflections and stored energy at each discontinuity. For large devices, with respect to a wavelength where many modes may propagate, the reflection and transmission properties may be required for a higher order mode or series of modes exciting the device. Such interactions are represented best by defining a scattering matrix for the device. The matrix can be determined by using mode matching at each discontinuity present. The results for individual discontinuities are then cascaded to
Developments of UTDefect: Rough rectangular cracks, anisotropy, etc
International Nuclear Information System (INIS)
The computer program UTDefect models the ultrasonic nondestructive testing of some simply shaped defects in an isotropic and homogeneous component. Such a model can be useful for educational purposes, for parametric studies, for the development of testing procedures, for the development of signal processing and data inversion procedures, and for the qualification of NDT procedures and personnel. The present report describes some recent developments of UTDefect. The list of defects has been increased by adding the rectangular crack. This crack can lie close to a planar back surface and the crack and back surface can be tilted independently. As a special option the rectangular crack may have rough faces. The deviation from a flat crack face is modelled as a sum of sinusoids with random phases. This gives a deterministic surface with given rms height and correlation length that looks reasonably like a real rough crack. For the roughness a perturbation approach is taken and this means that the rms height must be much smaller than both the ultrasonic wavelength and the correlation length. The scattering problem for the rectangular crack is solved by the same type of integral equation method that is employed for the other crack types in UTDefect. Due to the truly 3D character of the rectangular crack, the system matrices grow very quickly with frequency and the rectangular crack must therefore be less than six wavelengths across. The list of probes in UTDefect has been increased by adding immersion probes. As with contact probes these can be of rectangular or elliptic shape and they can be arbitrarily angled. At present the immersion probes cannot be focused. For the contact probes a far field approximation (the stationary phase method) is performed in UTDefect (if necessary with a probe subdivision). This is much more involved for immersion probes, so instead an exact integration is performed. So far the exact integration has been implemented for all defect types except
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
Investigation of imaging properties for submillimeter rectangular pinholes
Energy Technology Data Exchange (ETDEWEB)
Xia, Dan, E-mail: dxia@uchicago.edu [The Department of Radiology, The University of Chicago, Chicago, Illinois 60637 (United States); Moore, Stephen C., E-mail: scmoore@bwh.harvard.edu, E-mail: miaepark@bwh.harvard.edu, E-mail: mcervo@bwh.harvard.edu; Park, Mi-Ae, E-mail: scmoore@bwh.harvard.edu, E-mail: miaepark@bwh.harvard.edu, E-mail: mcervo@bwh.harvard.edu; Cervo, Morgan, E-mail: scmoore@bwh.harvard.edu, E-mail: miaepark@bwh.harvard.edu, E-mail: mcervo@bwh.harvard.edu [Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts 02115 (United States); Metzler, Scott D., E-mail: metzler@upenn.edu [The Department of Radiology, The University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)
2015-12-15
Purpose: Recently, a multipinhole collimator with inserts that have both rectangular apertures and rectangular fields of view (FOVs) has been proposed for SPECT imaging since it can tile the projection onto the detector efficiently and the FOVs in transverse and axial directions become separable. The purpose of this study is to investigate the image properties of rectangular-aperture pinholes with submillimeter apertures sizes. Methods: In this work, the authors have conducted sensitivity and FOV experiments for 18 replicates of a prototype insert fabricated in platinum/iridium (Pt/Ir) alloy with submillimeter square-apertures. A sin{sup q}θ fit to the experimental sensitivity has been performed for these inserts. For the FOV measurement, the authors have proposed a new formula to calculate the projection intensity of a flood image on the detector, taking into account the penumbra effect. By fitting this formula to the measured projection data, the authors obtained the acceptance angles. Results: The mean (standard deviation) of fitted sensitivity exponents q and effective edge lengths w{sub e} were, respectively, 10.8 (1.8) and 0.38 mm (0.02 mm), which were close to the values, 7.84 and 0.396 mm, obtained from Monte Carlo calculations using the parameters of the designed inserts. For the FOV measurement, the mean (standard deviation) of the transverse and axial acceptances were 35.0° (1.2°) and 30.5° (1.6°), which are in good agreement with the designed values (34.3° and 29.9°). Conclusions: These results showed that the physical properties of the fabricated inserts with submillimeter aperture size matched our design well.
Sloshing roof impact tests of a rectangular tank
International Nuclear Information System (INIS)
Some tanks have been damaged at the roofs due to sloshing impact caused by strong earthquakes. It is, therefore, necessary to consider the impact force in the aseismic design code for tank roofs. However, there are few studies on the earthquake responses of storage and process tank roofs. As a first step to investigate the effects of sloshing impact a series of the shaking table tests of a rectangular tank have been conducted at the National Research Institute for Earth Science and Disaster Prevention (NIED). The results of these shaking table tests are presented in the paper. The test tank is rectangular in shape having dimensions of 5 m x 3 m x 2 m length x width x height). The tank was constructed of glass-fiber reinforced plastic panels. Every panel had a flange on four edges, and each panel was connected by bolts along the flange. The test tank was set on the NIED shaking table (15 m by 15 m). Two types of liquid were used, water and a viscous liquid (water mixed with polymeric powders). The roof impact pressures and other quantities were measured. During the tests using the 400 pi El-Centro excitation, the roof deformation sensor steel beam was damaged. The response of side walls with different rigidity were measured in the wall bulging tests. The measured vibrations within the panel plates were larger than those in the panel flanges. The viscous liquid of 100 cp had little influence on wall bulging responses. However, the viscous effects on sloshing responses were observed in the sloshing tests. Approximate analyses of rectangular tanks, considering the influence of static water pressure, are also presented in this paper
Sloshing roof impact tests of a rectangular tank
Minowa, Chikahiro; Ogawa, Nobuyuki; Harada, Iki; Ma, David C.
Some tanks have been damaged at the roofs due to sloshing impact caused by strong earthquakes. It is, therefore, necessary to consider the impact force in the aseismic design code for tank roofs. However, there are few studies on the earthquake responses of storage and process tank roofs. As a first step to investigate the effects of sloshing impact a series of the shaking table tests of a rectangular tank have been conducted at the National Research Institute for Earth Science and Disaster Prevention (NIED). The results of these shaking table tests are presented in the paper. The test tank is rectangular in shape having dimensions of 5 m x 3 m x 2 m (length x width x height). The tank was constructed of glass-fiber reinforced plastic panels. Every panel had a flange on four edges, and each panel was connected by bolts along the flange. The test tank was set on the NIED shaking table (15 m by 15 m). Two types of liquid were used, water and a viscous liquid (water mixed with polymeric powders). The roof impact pressures and other quantities were measured. During the tests using the 400 pi El-Centro excitation, the roof deformation sensor steel beam was damaged. The response of side walls with different rigidity were measured in the wall bulging tests. The measured vibrations within the panel plates were larger than those in the panel flanges. The viscous liquid of 100 cp had little influence on wall bulging responses. However, the viscous effects on sloshing responses were observed in the sloshing tests. Approximate analyses of rectangular tanks, considering the influence of static water pressure, are also presented in this paper.
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
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.
Design of optimal chamfered bends in Rectangular Substrate Integrated Waveguide
Directory of Open Access Journals (Sweden)
Rahali Bochra
2011-07-01
Full Text Available Recently, has emerged a new technology, substrate integrated waveguide (SIW, it has been applied successfully to the conception of planar compact components for the microwave and millimeter waves applications. Our study concerns the analysis of right bends of rectangular waveguides under SIW technology by the HFSS code, in order to simulate different chamfrain positions, through the analysis of the transmission coefficient S21. In order to reduce losses of the performance, it is usual to chamfrain the external wall of the waveguide. Thus, through this modeling, we have confirmed the optimal position of the chamfrain. A good agreement between HFSS simulations and reference results has been obtained.
The kernel of the adjacency matrix of a rectangular mesh
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...
Nonlinear dynamics and control of a vibrating rectangular plate
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.
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.
Damage Analysis of Rectangular Section Composite Beam under Pure Bending
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.
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.
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.)
Extending the MODPATH algorithm to rectangular unstructured grids
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.
Experimental Study of Near Wake Flow Behind a Rectangular Cylinder
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...
Modeling of a nanoscale rectangular hole in a real metal.
Kumar, Arun; Srivastava, Triranjita
2008-02-15
We propose and implement a simple and accurate method to analyze a subwavelength rectangular hole in a real metal and obtain the modal characteristics of its fundamental mode. Our results are found to be in excellent agreement with those reported in the literature, obtained by the effective index method (EIM) and finite-element and finite-difference methods. Unlike the EIM, the present method has no ambiguity in its implementation and is able to predict the major field components also, which may be useful in understanding the extraordinary transmission characteristics of such structures. PMID:18278101
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.
A Piston-Rotaxane with Two Potential Stripes: Force Transitions and Yield Stresses
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...
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
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.
The effect of electrode material on the motion of a plasma piston in rail accelerators
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.
Numerical investigations of Piston mode resonance in a moonpool using OpenFOAM
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...
Influence of piston displacement on the scavenging and swirling flow in two-stroke diesel engines
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...
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.
DEFF Research Database (Denmark)
Christiansen, Jens; Klit, Peder; Vølund, Anders;
2007-01-01
engine. The basic idea is to use the fluid film damping coefficients to estimate the film thickness variation for a piston ring under cyclic varying load. Reynolds Equation is solved for a piston ring and the oil film thickness is determined. In this analysis hydrodynamic lubrication is assumed and the...
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.
Teodora Susana Oros; Ioan Berinde
2014-01-01
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 ...
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.
Díaz Caballero, Elena; Roldán, Isaac; Urrea Micó, Verónica; Chudzik, Magdalena; Arregui, Iván; Arnedo, Israel; Belenguer, Angel
2014-01-01
The guidelines for mapping rectangular waveguide structures to substrate integrated waveguide (SIW) technology are well understood for structures with straight walls. However, the mapping of a smooth profile structure from rectangular waveguide to SIW technology is not trivial and it needs to be carefully studied. A general procedure for mapping any smooth profile H-plane rectangular waveguide structure to SIW technology is proposed. A practical example is also provided and experimentally val...
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...... changes in radii is analysed. A numerical model based on the finite difference method in 1D has been developed for solving Reynold’s equation in combination with the load equilibrium equation together with flow continuity between the piston ring surface and liner for analysis of the lubricant transport....... The cyclic variation throughout one stroke is presented for the minimum film thicknesses at different interesting locations of the piston ring surface together with the friction and the pressure distribution history. The before mentioned parameters have been investigated numerically. The numerical...
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.
RECTANGULAR STORM SEWER DESIGN UNDER EQUAL SEDIMENT MOBILITY
Directory of Open Access Journals (Sweden)
Jaber Almedeij
2012-01-01
Full Text Available Rectangular storm sewers are conduits delivering water to outfall locations and have sizes that are typically larger than standard pipes, by which they become subject to more sediment deposits during operation and thus require higher flow strengths to maintain the bed clean. This study suggests a design procedure of self-cleansing rectangular sewers based on maintaining a lower limit of Shields stress and an upper limit of dimensionless bedload transport capacity. The lower limit of Shields stress is proposed under two considerations: to sustain equal sediment mobility at the channel bottom instead of selective transport and to avoid progressive deposition of finer grains due to low and reducing flows. The upper dimensionless bedload capacity is determined rationally and confirmed by using experimental data obtained from the literature. An existing bedload transport equation developed under equal sediment mobility is modified to provide a basis for the design method. It is shown that the proposed design procedure can practically be applied for a channel to estimate sediment concentrations by setting the required flow strength of Shields tress and particle size. Charts are given as an example for determining explicitly the channel design parameters. The study demonstrates that despite the high flows imposed, the design specifications determined according to this criterion can reasonably be achieved in practice for a given project.
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
Efficient and accurate sound propagation using adaptive rectangular decomposition.
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
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
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)
Sampling requirements for forage quality characterization of rectangular hay bales
Energy Technology Data Exchange (ETDEWEB)
Sheaffer, C.C.; Martin, N.P.; Jewett, J.G.; Halgerson, J.; Moon, R.D.; Cuomo, G.R.
2000-02-01
Commercial lots of alfalfa (Medicago sativa L.) hay are often bought and sold on the basis of forage quality. Proper sampling is essential to obtain accurate forage quality results for pricing of alfalfa hay, but information about sampling is limited to small, 20- to 40-kg rectangular bales. Their objectives were to determine the within-bale variation in 400-kg rectangular bales and to determine the number and distribution of core samples required to represent the crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and dry matter (DM) concentration in commercial lots of alfalfa hay. Four bales were selected from each of three hay lots and core sampled nine times per side for a total of 54 cores per bale. There was no consistent pattern of forage quality variation within bales. Averaged across lots, any portion of a bale was highly correlated with bale grand means for CP, ADF, NDF, and DM. Three lots of hay were probed six times per bale, one core per bale side from 55, 14, and 14 bales per lot. For determination of CP, ADF, NDF, and DM concentration, total core numbers required to achieve an acceptable standard error (SE) were minimized by sampling once per bale. Bootstrap analysis of data from the most variable hay lot suggested that forage quality of any lot of 400-kg alfalfa hay bales should be adequately represented by 12 bales sampled once per bale.
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.
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
Versatile patterns of multiple rectangular noise-like pulses in a fiber laser.
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
Determination of tension of friction of piston of dispersible material is in a pipeline
Directory of Open Access Journals (Sweden)
Vasilevsky Michail
2015-01-01
Full Text Available Estimates of the piston friction stress of particulate material in the pipe by mechanical action of the plunger. The material is compacted to form the roof and moves as a whole. The ranges of the coefficients of lateral pressure and coulomb friction.
Avco Lycoming/NASA contract status. [on reduction of emissions from aircraft piston engines
Duke, L. C.
1976-01-01
The standards promulgated by the Environmental Protection Agency (EPA) for carbon monoxide (CO), unburned hydrocarbon (HC), and oxides-of-nitrogen (NOx) emissions were the basis in a study of ways to reduce emissions from aircraft piston engines. A variable valve timing system, ultrasonic fuel atomization, and ignition system changes were postulated.
Design and Commissioning of a New Lightweight Piston for the X3 Expansion Tube
Gildfind, D. E.; Morgan, R. G.; Sancho, J.
The University of Queensland's (UQ) X3 facility (Figure 1) is the world's largest free-piston driven expansion tube. It is used to generate hypersonic test flows such as simulation of planetary entry (6-15 km/s) or scramjet flight (3-5 km/s).
The Development of a Control System for a 5 Kilowatt Free Piston Stirling Engine Convertor
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.
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.
Tribological Performance of Different Geometries of Piston Rings in Marine Diesel Engines
DEFF Research Database (Denmark)
Imran, Tajammal; Klit, Peder; Felter, Christian;
are manufactured from real piston ring material. The mating slider is manufactured from cylinder liner material. Experiments are conducted at five different speeds and a fixed dead-weight loading. The friction force and the bulk temperature of the test specimen are recorded as a function of crank angle position...
Optimal piston motion for maximum net output work of Daniel cam engines with low heat rejection
International Nuclear Information System (INIS)
Highlights: • The piston motion of low heat rejection compression ignition engines is optimized. • A realistic model taking into account the cooling system is developed. • The optimized cam is smaller for cylinders without thermal insulation. • The optimized cam size depends on ignition moment and cooling process intensity. - Abstract: Compression ignition engines based on classical tapper-crank systems cannot provide optimal piston motion. Cam engines are more appropriate for this purpose. In this paper the piston motion of a Daniel cam engine is optimized. Piston acceleration is taken as a control. The objective is to maximize the net output work during the compression and power strokes. A major research effort has been allocated in the last two decades for the development of low heat rejection engines. A thermally insulated cylinder is considered and a realistic model taking into account the cooling system is developed. The sinusoidal approximation of piston motion in the classical tapper-crank system overestimates the engine efficiency. The exact description of the piston motion in tapper-crank system is used here as a reference. The radiation process has negligible effects during the optimization. The approach with no constraint on piston acceleration is a reasonable approximation. The net output work is much larger (by 12–13%) for the optimized system than for the classical tapper-crank system, for similar thickness of cylinder walls and thermal insulation. Low heat rejection measures are not of significant importance for optimized cam engines. The optimized cam is smaller for a cylinder without thermal insulation than for an insulated cylinder (by up to 8%, depending on the local polar radius). The auto-ignition moment is not a parameter of significant importance for optimized cam engines. However, for given cylinder wall and insulation materials there is an optimum auto-ignition moment which maximizes the net output work. The optimum auto
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.
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
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.
Rectangular Waveguide HOM Couplers for a TESLA Superstructure
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.
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.
Thermoelectric effects in a rectangular Aharonov-Bohm geometry
Pye, A. J.; Faux, D. A.; Kearney, M. J.
2016-04-01
The thermoelectric transport properties of a rectangular Aharonov-Bohm ring at low temperature are investigated using a theoretical approach based on Green's functions. The oscillations in the transmission coefficient as the field is varied can be used to tune the thermoelectric response of the ring. Large magnitude thermopowers are obtainable which, in conjunction with low conductance, can result in a high thermoelectric figure of merit. The effects of single site impurities and more general Anderson disorder are considered explicitly in the context of evaluating their effect on the Fano-type resonances in the transmission coefficient. Importantly, it is shown that even for moderate levels of disorder, the thermoelectric figure of merit can remain significant, increasing the appeal of such structures from the perspective of specialist thermoelectric applications.
Incompressible Laminar Flow Over a Three-Dimensional Rectangular Cavity
Institute of Scientific and Technical Information of China (English)
无
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.
Oscillating laminar electrokinetic flow in infinitely extended rectangular microchannels.
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
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
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.
Calculation of wakefields in 2D rectangular structures
International Nuclear Information System (INIS)
We consider the calculation of electromagnetic fields generated by an electron bunch passing through a vacuum chamber structure that, in general, consists of an entry pipe, followed by some kind of transition or cavity, and ending in an exit pipe. We limit our study to structures having rectangular cross-section, where the height can vary as function of longitudinal coordinate but the width and side walls remain fixed. For such structures, we derive a Fourier representation of the wake potentials through one-dimensional functions. A new numerical approach for calculating the wakes in such structures is proposed and implemented in the computer code ECHO(2D). The computation resource requirements for this approach are moderate and comparable to those for finding the wakes in 2D rotationally symmetric structures. Numerical examples obtained with the new numerical code are presented.
Electron Acceleration by Microwave Radiation Inside Rectangular Waveguide
International Nuclear Information System (INIS)
The dynamics of an electron in the fields associated with transverse magnetic (TM) wave propagating inside rectangular waveguide is studied analytically. We have solved exactly the relativistic momentum and energy equations of a single electron which injected initially along the propagation of microwave. Expressions for the acceleration gradient and deflection angle are obtained. In principle, it is shown that the energy of the electron can be accelerated in this environment and there is no deflection when the electron is injected from centre of the waveguide front. However, it is found that, the acceleration gradient and deflection angle are strongly depended on the parameters of microwave (intensity, frequency o.. etc) and the dimensions of waveguide
Electron Acceleration by Microwave Radiation Inside a Rectangular Waveguide
International Nuclear Information System (INIS)
Electron dynamics in the fields associated with a transverse magnetic (TM) wave propagating inside a rectangular waveguide is analytically studied. The relativistic momentum and energy equations for an electron are solved, which was injected initially along the propagation direction of the microwave. Expressions of the acceleration gradient and deflection angle are obtained. In principle, it is shown that the electron can be accelerated in this condition and there is no deflection when the electron is injected from the centre of the waveguide front. However, it is found that the acceleration gradient and deflection angle depend strongly on the parameters of the microwave (intensity, frequency, etc.) and the dimensions of the waveguide. (inertially confined plasma)
Rectangular amplitudes, conformal blocks, and applications to loop models
Energy Technology Data Exchange (ETDEWEB)
Bondesan, Roberto, E-mail: roberto.bondesan@cea.fr [LPTENS, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris (France); Institute de Physique Theorique, CEA Saclay, F-91191 Gif-sur-Yvette (France); Jacobsen, Jesper L. [LPTENS, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris (France); Universite Pierre et Marie Curie, 4 place Jussieu, 75252 Paris (France); Saleur, Hubert [Institute de Physique Theorique, CEA Saclay, F-91191 Gif-sur-Yvette (France); Physics Department, USC, Los Angeles, CA 90089-0484 (United States)
2013-02-21
In this paper we continue the investigation of partition functions of critical systems on a rectangle initiated in [R. Bondesan, et al., Nucl. Phys. B 862 (2012) 553-575]. Here we develop a general formalism of rectangle boundary states using conformal field theory, adapted to describe geometries supporting different boundary conditions. We discuss the computation of rectangular amplitudes and their modular properties, presenting explicit results for the case of free theories. In a second part of the paper we focus on applications to loop models, discussing in details lattice discretizations using both numerical and analytical calculations. These results allow to interpret geometrically conformal blocks, and as an application we derive new probability formulas for self-avoiding walks.
Flutter Speed Limits of Cantilever Rectangular and Tapered Plates
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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.
Vibrations of cantilevered shallow cylindrical shells of rectangular planform
Leissa, A. W.; Lee, J. K.; Wang, A. J.
1981-10-01
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.
Performance analysis of SOI MOSFET with rectangular recessed channel
Singh, M.; Mishra, S.; Mohanty, S. S.; Mishra, G. P.
2016-03-01
In this paper a two dimensional (2D) rectangular recessed channel-silicon on insulator metal oxide semiconductor field effect transistor (RRC-SOI MOSFET), using the concept of groove between source and drain regions, which is one of the channel engineering technique to suppress the short channel effect (SCE). This suppression is mainly due to corner potential barrier of the groove and the simulation is carried out by using ATLAS 2D device simulator. To have further improvement of SCE in RRC-SOI MOSFET, three more devices are designed by using dual material gate (DMG) and gate dielectric technique, which results in formation of devices i.e. DMRRC-SOI,MLSMRRC-SOI, MLDMRRC-SOI MOSFET. The effect of different structures of RRC-SOI on AC and RF parameters are investigated and the importance of these devices over RRC MOSFET regarding short channel effect is analyzed.
Some new results of the Casimir force for rectangular cavity
Energy Technology Data Exchange (ETDEWEB)
Zhai, X.-H.; Li, X.-Z. [Shanghai Normal University, Dept. of Physics, Shanghai (China)
2001-10-01
The Casimir effect giving rise to an attractive or repulsive force between the configuration boundaries that confine the massless scalar field is analytically approached for a p-dimensional rectangular cavity with the Dirichlet boundary conditions and different spacetime dimensions D. The Casimir force is attractive in the cases: i) p-odd hypercube when D is less than the critical dimension D{sub c} and p {<=} 29; ii) o =2 and the length ratio is less than a critical value; iii) p = 1. The Casimir force is repulsive in the cases: i) p = 2 and the length ratio is larger than a critical value; ii) the length of q edges is equal and others are much longer than q edges, in the direction of (p-q) edges; iii) (p-q) edges are much longer than q edges, in the direction of (p-q) edges.
Stability Analysis of Nonuniform Rectangular Beams Using Homotopy Perturbation Method
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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.
Flow and cooling in narrow, vertical rectangular channels
International Nuclear Information System (INIS)
Laminar flows and energy transfers in narrow, vertical rectangular channels has gained considerable attention in recent years. the cooling channels of TR-2 reactor of CNAEM research center are same and the width of channels is 2.1 mm. Natural convention cooling in these channels, in case of a loss of forced circulation cooling, as would happen in a accident, has utmost importance. A simple open loop experiment was set up in Nuclear Engineering Dep. for the simulation of TR-2 channels. The dummy fuel plates defining cooling channels were heated electrically and temperature measurements were made by thin wire thermocouples. The fluid used at the moment is air. Constant heat flux case was studied only. For the comparison purposes, simplified forms of Navie-Stokes equations for free convention cooling and incompressible flows were solved also on a variable mesh grid by relaxation technique. Flow and temperature distributions inside the channel nad some integral parameters, such as Nu number, were obtained
Aerodynamic characteristics of bodies with rectangular cross section
Knoche, H. G.; Schamel, W.; Esch, H.; Schneider, W.
Systematic wind tunnel tests for a series of missile bodies were conducted by varying cross section shape and body length in the subsonic Mach number range and up to high angles of attack. Tests with a body-wing and a body-tail configuration were performed in order to investigate the body-wing and body-tail interference for bodies of revolution and bodies with rectangular cross section. At a constant angle of attack, the boxlike body supplies far more normal force than the body of revolution with the same cross section area. The boxlike body shows strong coupling effects between the pitch, yaw and roll. The interference effect of the wing and body can be described well, in the case of boxlike bodies with wings in high or low wing positions, by the known slender body interference factors, assuming the width of the box to be the diameter of an equivalent, axially symetrical body.
Vibrations of cantilevered shallow cylindrical shells of rectangular planform
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.
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.
Flow characteristics in a rectangular vessel due to gas entrainment
International Nuclear Information System (INIS)
The authors investigated hydrodynamic factors to cause the gas entrainment from the surface of coolant flowing in a reactor vessel. The flow characteristics were established for the water flow, which is fed into a three-dimensional rectangular cell that represents the flow field in a reactor. Existence of predominant types of flow, such as the colliding flow, circulating flow and vertical eddy, were established by results of measurement on the distribution of flow velocity. The steady state three-dimensional flow in the flow field was also demonstrated. Difference in the flow velocity between area at the center of water tank and near the side wall of it and momentary variation of three-dimensional flow velocity near the water surface were also found. It was concluded from these results that the air entrainment is caused by the interference between the steady state circulating flow and momentary and local variation of flow velocity. (author)
Extension of Marcatili's analytical approach for rectangular silicon optical waveguides
Westerveld, W J; van Dongen, K W A; Urbach, H P; Yousefi, M
2015-01-01
Marcatili's famous approximate analytical description of light propagating through rectangular dielectric waveguides, published in 1969, gives accurate results for low-index-contrast waveguides. However, photonic integrated circuit technology has advanced to high-index-contrast (HIC) waveguides. In this paper, we improve Marcatili's model by adjusting the amplitudes of the components of the electromagnetic fields in his description. We find that Marcatili's eigenvalue equation for the propagation constant is also valid for HIC waveguides. Our improved method shows much better agreement with rigorous numerical simulations, in particular for the case of HIC waveguides. We also derive explicit expressions for the effective group index and the effects of external forces on the propagation constant. Furthermore, with our method the phenomenon of avoided crossing of modes is observed and studied.
Measurement of electron beam bunch phase length by rectangular cavities
International Nuclear Information System (INIS)
An analysis of a phase length of electron bunches with the help of crossed rectangular resonators with the Hsub(102) oscillation type has been made. It has been shown that the electron coordinates after the duplex resonator are described by an ellipse equation for a non-modulated beam. An influence of the initial energy spread upon the electron motion has been studied. It has been ascertained that energy modulation of the electron beam results in displacement of each electron with respect to the ellipse which is proportional to modulation energy, i.e. an error in determination of the phase length of an electron bunch is proportional to the beam energy spread. Relations have been obtained which enable to find genuine values of phases of the analyzed electrons with an accuracy up to linear multipliers
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.
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.)
Wongthep, Padipat; RABAULT, Thierry; Noguera, Ricardo; SARRAF, Christophe
2013-01-01
This paper aims to investigate, by means of numerical simulation, the effect of gap profiles on the calculation of the pressure distortion coefficient (λ) and the piston fall rate (vf) of two piston-cylinder units used in a Laboratoire National de Métrologie et d'Essais (LNE) 200 MPa pressure balance. The ideal mean gap width between the piston and the cylinder was obtained after measuring the piston fall rate at a low pressure, while the piston radius was obtained from the cross-float experi...
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, th...
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.
Finite element fatigue analysis of rectangular clutch spring of automatic slack adjuster
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.
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.
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.
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.
Pressure increase in two-phase media behind air shock waves and by shock wave accelerated pistons
Patz, G.; Smeets, G.
Results are summarized from experimental and theoretical studies of the effects of a shock wave on a two-phase medium (TPM) and the compression of a TPM by a piston accelerated by the pressure behind a reflected shock. Attention is also given to the use of foam as the TPM and actions of the changing pressure as the shock moves to the end of the shock tube and returns. The situation is extended to the situation where the returning wave drives a piston into the foam. Analysis of the pressure variations in the foam shows that the peak pressure will depend only on the piston pressure. No shocks formed in the TMP, either in the model predictions or in an experimental validation, because the piston speed was always well below the sonic velocity in the lather.
Kutin, J.; Bobovnik, G.; Bajsić, I.
2015-12-01
This paper deals with heat exchange effects in a compact, high-speed, clearance-sealed version of a piston prover for gas flow measurements that has the temperature measurements limited to the time-averaged temperature of the gas flow. A lumped-element mathematical model is used to study the physical background of the heat exchange effects. Experimental testing is performed to validate the theoretical results, estimate the required temperature homogeneity in the piston prover and propose a modified measurement model that considers the heat exchange effects. These effects are almost linearly related to the temperature difference between the gas flow into the piston prover and the cylinder wall, with the sensitivity coefficient being dependent on the measured flow rate. The piston-prover configuration with the gas temperature sensor in the mixed inlet /outlet flow is found to be advantageous in comparison to a measurement of the inlet temperature.
Directory of Open Access Journals (Sweden)
M. Gulzar
2013-12-01
Full Text Available At initial engine start-up, the low speeds take time to develop considerable film thickness between piston and liner surfaces. Factors like radial clearance, oil viscosity and roughness of interacting surfaces play an important role in this regard. A two dimensional model is presented for hydrodynamic lubrication and EHL of rough piston skirt under isothermal conditions. Flow factors method is used to incorporate the deterministic isotropic roughness effects in Reynolds’ equation and Greenwood-Tripp asperity contact model is used for involving the corresponding asperity contact forces and moments. The numerical model is used to get simulation results including piston eccentric displacements, hydrodynamic and EHL film thickness and rising pressures for 10 micron and 100 micron radial clearance between piston and liner. All results are plotted against 720 degree crank rotation cycle. The results show considerable change in each parameter by changing radial clearance from small value to large.
Energy Technology Data Exchange (ETDEWEB)
Balakrishnan, S; Rahnejat, H [Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough (United Kingdom)
2005-03-07
The paper describes the combined axial, lateral and tilting motions of piston within the confine of cylinder bore, with sliding and normally approaching and separating contacts between the piston skirt and the cylinder wall on both the major and minor thrust sides. The methodology developed undertakes combined solution for inertial dynamics of the piston, together with transient elastohydrodynamic analysis of both contacts. It also includes important practical features of the contacting surfaces, such as the axial form relieving of the piston skirt profile. The space-time solver uses Newmark {beta}-type time marching integrator, as well as the effective influence Newton-Raphson method for space-domain solution of the elastohydrodynamic conjunctions in each step of time. This approach, not hitherto reported for this type of conforming contacts yields accurate predictions of lubricant film thickness and pressure distribution within computationally acceptable times, given the inclusion of level of detail in the model.
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.
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.
TFSSRA - THICK FREQUENCY SELECTIVE SURFACE WITH RECTANGULAR APERTURES
Chen, J. C.
1994-01-01
Thick Frequency Selective Surface with Rectangular Apertures (TFSSRA) was developed to calculate the scattering parameters for a thick frequency selective surface with rectangular apertures on a skew grid at oblique angle of incidence. The method of moments is used to transform the integral equation into a matrix equation suitable for evaluation on a digital computer. TFSSRA predicts the reflection and transmission characteristics of a thick frequency selective surface for both TE and TM orthogonal linearly polarized plane waves. A model of a half-space infinite array is used in the analysis. A complete set of basis functions with unknown coefficients is developed for the waveguide region (waveguide modes) and for the free space region (Floquet modes) in order to represent the electromagnetic fields. To ensure the convergence of the solutions, the number of waveguide modes is adjustable. The method of moments is used to compute the unknown mode coefficients. Then, the scattering matrix of the half-space infinite array is calculated. Next, the reference plane of the scattering matrix is moved half a plate thickness in the negative z-direction, and a frequency selective surface of finite thickness is synthesized by positioning two plates of half-thickness back-to-back. The total scattering matrix is obtained by cascading the scattering matrices of the two half-space infinite arrays. TFSSRA is written in FORTRAN 77 with single precision. It has been successfully implemented on a Sun4 series computer running SunOS, an IBM PC compatible running MS-DOS, and a CRAY series computer running UNICOS, and should run on other systems with slight modifications. Double precision is recommended for running on a PC if many modes are used or if high accuracy is required. This package requires the LINPACK math library, which is included. TFSSRA requires 1Mb of RAM for execution. The standard distribution medium for this program is one 5.25 inch 360K MS-DOS format diskette. It is also
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
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.
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
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.
Electrothermally actuated tip-tilt-piston micromirror with integrated varifocal capability.
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
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.
The intermetallic bonding between a ring carrier and aluminum piston alloy
International Nuclear Information System (INIS)
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)