Spin wave eigenmodes in single and coupled sub-150 nm rectangular permalloy dots
Energy Technology Data Exchange (ETDEWEB)
Carlotti, G., E-mail: giovanni.carlotti@fisica.unipg.it; Madami, M. [Dipartimento di Fisica e Geologia, Università di Perugia, Perugia (Italy); Tacchi, S. [Istituto Officina dei Materiali del CNR (CNR-IOM), Dipartimento di Fisica e Geologia, Perugia (Italy); Gubbiotti, G.; Dey, H.; Csaba, G.; Porod, W. [Center for Nano Science and Technology, Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States)
2015-05-07
We present the results of a Brillouin light scattering investigation of thermally excited spin wave eigenmodes in square arrays of either isolated rectangular dots of permalloy or twins of dipolarly coupled elements, placed side-by-side or head-to-tail. The nanodots, fabricated by e-beam lithography and lift-off, are 20 nm thick and have the major size D in the range between 90 nm and 150 nm. The experimental spectra show the presence of two main peaks, corresponding to modes localized either at the edges or in the center of the dots. Their frequency dependence on the dot size and on the interaction with adjacent elements has been measured and successfully interpreted on the basis of dynamical micromagnetic simulations. The latter enabled us also to describe the spatial profile of the eigenmodes, putting in evidence the effects induced by the dipolar interaction between coupled dots. In particular, in twinned dots the demagnetizing field is appreciably modified in proximity of the “internal edges” if compared to the “external” ones, leading to a splitting of the edge mode. These results can be relevant for the exploitation of sub-150 nm magnetic dots in new applications, such as magnonic metamaterials, bit-patterned storage media, and nano-magnetic logic devices.
Magnetic domain wall motion in notch patterned permalloy nanowire devices
Energy Technology Data Exchange (ETDEWEB)
Chen, Ting-Chieh; Kuo, Cheng-Yi; Mishra, Amit K.; Das, Bipul; Wu, Jong-Ching, E-mail: phjcwu@cc.ncue.edu.tw
2015-11-01
We report a study of magnetization reversal process of notch-patterned permalloy (Py) nanowires (NWs) by using an in-situ magnetic force microscopy (MFM). Three neighboring straight NWs and an individual straight NW with discs connected to the wires ends are fabricated by standard electron beam lithography through a lift-off technique. MFM images are taken in the presence of an in-plane magnetic field applied along the wires length. As a result, the nucleation, pinning and depinning of domain walls (DWs) along the NW are observed. The artificial constraints (notch) in such symmetrical geometry of NWs indeed serve as pinning sites to pin the DWs. The nature of magnetization reversal, pinning field and depinning field for the DWs that are observed in these permalloy NWs, indicate the key roles of notch depth, the terminal connection structure of NW end and the inter-wire interaction among the NWs. The in-situ MFM measurements are examined with the micromagnetic simulations. Consequently, good agreements are obtained for the DW structures and the effect of DWs pining/depinning, however a dissimilarity in experimental and simulation observations for the direction of propagation of DWs in NWs needs further investigation.
Two-phase flow patterns in horizontal rectangular minichannel
Directory of Open Access Journals (Sweden)
Ron’shin Fedor
2016-01-01
Full Text Available The two-phase flow in a short horizontal channel of rectangular cross-section of 1 × 19 mm2 has been studied experimentally. Five conventional two-phase flow patterns have been detected (bubble, churn, stratified, annular and jet and transitions between them have been determined. It is shown that a change in the width of the horizontal channels has a substantial effect on the boundaries between the flow regimes.
Modeling on bubbly to churn flow pattern transition in narrow rectangular channel
International Nuclear Information System (INIS)
Wang Yanlin; Chen Bingde; Huang Yanping; Wang Junfeng
2012-01-01
A theoretical model based on some reasonable concepts was developed to predict the bubbly flow to churn flow pattern transition in vertical narrow rectangular channel under flow boiling condition. The maximum size of ideal bubble in narrow rectangular channel was calculated based on previous literature. The thermal hydraulics boundary condition of bubbly to churn flow pattern transition was exported from Helmholtz and maximum size of ideal bubble. The theoretical model was validated by existent experimental data. (authors)
International Nuclear Information System (INIS)
Wang Yanlin; Chen Bingde; Huang Yanping; Wang Junfeng
2011-01-01
A theoretical model was developed to predict the bubbly to churn flow pattern transition for vertical upward flows in narrow rectangular channel. The model was developed based on the imbalance theory of Helmholtz and some reasonable assumptions. The maximum ideal bubble in narrow rectangular channel and the thermal hydraulics boundary condition leading to bubbly flow to churn flow pattern transition was calculated. The model was validated by experimental data from previous researches. Comparison between predicted result and experimental result shows a reasonable good agreement. (author)
Magnetization in permalloy thin films
Indian Academy of Sciences (India)
Thin films of permalloy (Ni80Fe20) were prepared using an Ar+N2 mixture with magnetron ... alloys of Ni and Fe) take an important place. NiFe alloy with a ... room temperature (∼298 K, without intentional heating) on Si(100) substrates. A base pressure of 1×10−6 mbar was achieved prior to the deposition. Three different ...
Features of two-phase flow patterns in horizontal rectangular microchannels of height 50 μm
Directory of Open Access Journals (Sweden)
Ron’shin Fedor
2016-01-01
Full Text Available The horizontal microchannel with the height of 50 micrometres and width of 40 mm of a rectangular cross-section has been used to study two-phase flow. The classical patterns of two-phase flow in the channel (bubble, stratified, churn, jet, and annular have been detected. Experimental information allows us to define the characteristics of the regimes and to determine precisely the boundaries between the patterns of the two-phase flows.
International Nuclear Information System (INIS)
Wang Junfeng; Huang Yanping; Wang Yanlin
2011-01-01
Highlights: → Specific points on the demand curve and flow patterns are visually studied. → Bubbly, churn, and annular flows were observed. → Onset of flow instability and bubbly-churn transition occurs at the same time. → The evolution of specific points and flow pattern transitions were examined. - Abstract: A simultaneous visualization and measurement study on some specific points on demand curves, such as onset of nucleate boiling (ONB), onset of significant void (OSV), onset of flow instability (OFI), and two-phase flow patterns in a single-side heated narrow rectangular channel, having a width of 40 mm and a gap of 3 mm, was carried out. New experimental approaches were adopted to identify OSV and OFI in a narrow rectangular channel. Under experimental conditions, the ONB could be predicted well by the Sato and Matsumura model. The OSV model of Bowring can reasonably predict the OSV if the single-side heated condition is considered. The OFI was close to the saturated boiling point and could be described accurately by Kennedy's correlation. The two-phase flow patterns observed in this experiment could be classified into bubbly, churn, and annular flow. Slug flow was never observed. The OFI always occurred when the bubbles at the channel exit began to coalesce, which corresponded to the beginning of the bubbly-churn transition in flow patterns. Finally, the evolution of specific points and flow pattern transitions were examined in a single-side heated narrow rectangular channel.
Magnetic properties of permalloy-coated organic tubules
Krebs, J. J.; Rubinstein, M.; Lubitz, P.; Harford, M. Z.; Baral, S.; Shashidar, R.; Ho, Y. S.; Chow, G. M.; Qadri, S.
1991-11-01
An initial investigation is presented of the ferromagnetic properties of a novel type of magnetic composite, viz., permalloy-coated submicron diameter hollow cylinders or tubules. The tubules form spontaneously from an organic material, a diacetylenic phosopholipid, and were used as templates on which the ferromagnetic material was deposited by electroless deposition. The permalloy-coated tubules were dispersed in an epoxy matrix to measure the magnetization and ferromagnetic resonance (FMR) properties of individual tubules. The nature of the magnetic anisotropy and the FMR spectra observed confirmed that the tubules are well aligned by a magnetic field during the epoxy curing. The FMR spectra are interpreted in terms of a powder pattern distribution of thin-film spectra consistent with the large diameter-to-thickness ratio.
Directory of Open Access Journals (Sweden)
D. Zhang
2016-05-01
Full Text Available Patterned magnetic films with nano-scaled dots exhibit some special magnetic properties. In this paper, we investigate the in-plane shape anisotropy and the magnetization dynamic damping in permalloy (Ni80Fe20 arrays of submicron rectangular elements using ferromagnetic resonance (FMR. The FMR linewidth exhibits a dependence on the element size, and mainly comes from the contribution of the intrinsic damping. Also the contribution of two-magnon scattering plays an important role and is reduced with increasing aspect ratio. The damping coefficient decreases from 0.0129 to 0.0118 with the element length increasing from 300 nm to 1200 nm, and the theoretical calculation suggests that the change of damping results from the longitudinal and transverse interlayer spin current due to the spatially inhomogeneous magnetization dynamics.
Electroplating of low stress permalloy for MEMS
International Nuclear Information System (INIS)
Zhang Yonghua; Ding Guifu; Cai Yuli; Wang Hong; Cai Bingchu
2006-01-01
With the wafer-bending method and spectrophotometry, the internal stress in electroplated Ni-Fe alloy for MEMS has been investigated as a function of bath concentration. This investigation demonstrated that low concentration plating solution is useful for the decrease of the residual stress in the electrodeposits, and the stress could further decrease with an increase of saccharin additive content. And the change of stress from tensile to compressive was not observed with the increase of the additive content in plating path. The low stress permalloy (Ni 81 Fe 19 ) was reached in our experimental conditions. A bistable electromagnetic RF MEMS switch with deformation-free bilayer cantilever beam was fabricated successfully by electroplated permalloy
The Effect of Confluence Angle on the Flow Pattern at a Rectangular Open-Channel
Directory of Open Access Journals (Sweden)
F. Rooniyan
2014-02-01
Full Text Available Flow connection in channels is a phenomenon which frequently happens in rivers, water and drainage channels and urban sewage systems. The phenomenon appears to be more complex in rivers than in channels, especially at the y-junction bed joint that causes erosion and sedimentation at some areas resulting to morphological changes. Flow behavior at the channel junction area depends on variables such as channel geometry, discharge ratio, tributary width and y-junction connection angle of the channel, bed level changes at the bed joint, flow characteristic at the bed joint upstream and flow Froude number in different sections. In this research, fluent numerical model and junction angles of 30o, 45o & 60o are used to analyze and evaluate the effect of channel junction geometry on the flow pattern and the flow separation zone dimensions in different ratios of flow discharge (upstream channel discharge to total discharge of the flow. Results for two ratios of flow discharge are represented. Results are in agreement with earlier studies and it is shown that the change of the channel crossing angle affects the flow pattern in the main channel and also that the dimensions of the created separation zone in the main channel become larger when the crossing angle increases. This phenomenon can also be observed when the flow discharge ratio is lower. Analysis showed that the least dimension of the separation zone will be at the crossing angle of 45o .
International Nuclear Information System (INIS)
Kozma, R.; van Dam, H.; Hoogenboom, J.E.
1992-01-01
The primary objective of this paper is to introduce results of coolant boiling experiments in a simulated materials test reactor-type fuel assembly with plate fuel in an actual reactor environment. The experiments have been performed in the Hoger Onderwijs Reactor (HOR) research reactor at the Interfaculty Reactor Institute, Delft, The Netherlands. In the analysis, noise signals of self-powered neutron detectors located in the neighborhood of the boiling region and thermocouple in the channel wall and in the coolant are used. Flow patterns in the boiling coolant have been identified by means of analysis of probability density functions and power spectral densities of neutron noise. It is shown that boiling has an oscillating character due to partial channel blockage caused by steam slugs generated periodically between the plates. The observed phenomenon can serve as a basis for a boiling detection method in reactors with plate-type fuels
Energy Technology Data Exchange (ETDEWEB)
Zhang, D. [Department of Physics, Southeast University, Nanjing, 211189 (China); School of Physical Science and Information Engineering, Liaocheng University, Liaocheng, 252059 (China); Yue, J. J.; Kou, Z. X.; Lin, L. [Department of Physics, Southeast University, Nanjing, 211189 (China); Zhai, Y., E-mail: yazhai@seu.edu.cn [Department of Physics, Southeast University, Nanjing, 211189 (China); National Laboratory of Solid Microstructures, Nanjing University, Nanjing, 210093 (China); Zhai, H. R. [National Laboratory of Solid Microstructures, Nanjing University, Nanjing, 210093 (China)
2016-05-15
Patterned magnetic films with nano-scaled dots exhibit some special magnetic properties. In this paper, we investigate the in-plane shape anisotropy and the magnetization dynamic damping in permalloy (Ni{sub 80}Fe{sub 20}) arrays of submicron rectangular elements using ferromagnetic resonance (FMR). The FMR linewidth exhibits a dependence on the element size, and mainly comes from the contribution of the intrinsic damping. Also the contribution of two-magnon scattering plays an important role and is reduced with increasing aspect ratio. The damping coefficient decreases from 0.0129 to 0.0118 with the element length increasing from 300 nm to 1200 nm, and the theoretical calculation suggests that the change of damping results from the longitudinal and transverse interlayer spin current due to the spatially inhomogeneous magnetization dynamics.
Effect of spacer layer on the magnetization dynamics of permalloy/rare-earth/permalloy trilayers
International Nuclear Information System (INIS)
Luo, Chen; Yin, Yuli; Zhang, Dong; Jiang, Sheng; Yue, Jinjin; Zhai, Ya; Du, Jun; Zhai, Hongru
2015-01-01
The permalloy/rare-earth/permalloy trilayers with different types (Gd and Nd) and thicknesses of spacer layer are investigated using frequency dependence of ferromagnetic resonance (FMR) measurements at room temperature, which shows different behaviors with different rare earth spacer layers. By fitting the frequency dependence of the FMR resonance field and linewidth, we find that the in-plane uniaxial anisotropy retains its value for all samples, the perpendicular anisotropy remains almost unchanged for different thickness of Gd layer but the values are tailored by different thicknesses of Nd layer. The Gilbert damping is almost unchanged with different thicknesses of Gd; however, the Gilbert damping is significantly enhanced from 8.4×10 −3 to 20.1×10 −3 with 6 nm of Nd and then flatten out when the Nd thickness rises above 6 nm
Directory of Open Access Journals (Sweden)
Raj Kumar
2016-05-01
Full Text Available In this work, the effect of angle of attack ( α a of the discrete V-pattern baffle on thermohydraulic performance of rectangular channel has been studied experimentally. The baffle wall was constantly heated and the other three walls of the channel were kept insulated. The experimentations were conducted to collect the data on Nusselt number ( N u b and friction factor ( f b by varying the Reynolds number (Re = 3000–21,000 and angle of attack ( α a from 30° to 70°, for the kept values of relative baffle height ( H b / H = 0 . 50 , relative pitch ratio ( P b / H = 1 . 0 , relative discrete width ( g w / H b = 1 . 5 and relative discrete distance ( D d / L v = 0 . 67 . As compared to the smooth wall, the V-pattern baffle roughened channel enhances the Nusselt number ( N u b and friction factor ( f b by 4.2 and 5.9 times, respectively. The present discrete V-pattern baffle shapes with angle of attack ( α a of 60° equivalent to flow Reynolds number of 3000 yields the greatest thermohydraulic performance. Discrete V-pattern baffle has improved thermal performance as compared to other baffle shapes’ rectangular channel.
Ferromagnetic resonance in a topographically modulated permalloy film
Sklenar, J.; Tucciarone, P.; Lee, R. J.; Tice, D.; Chang, R. P. H.; Lee, S. J.; Nevirkovets, I. P.; Heinonen, O.; Ketterson, J. B.
2015-04-01
A major focus within the field of magnonics involves the manipulation and control of spin-wave modes. This is usually done by patterning continuous soft magnetic films. Here, we report on work in which we use topographic modifications of a continuous magnetic thin film, rather than lithographic patterning techniques, to modify the ferromagnetic resonance spectrum. To demonstrate this technique we have performed in-plane, broadband, ferromagnetic resonance studies on a 100-nm-thick permalloy film sputtered onto a colloidal crystal with individual sphere diameters of 200 nm. Effects resulting from the, ideally, sixfold-symmetric underlying colloidal crystal were studied as a function of the in-plane field angle through experiment and micromagnetic modeling. Experimentally, we find two primary modes; the ratio of the intensities of these two modes exhibits a sixfold dependence. Detailed micromagnetic modeling shows that both modes are quasiuniform and nodeless in the unit cell but that they reside in different demagnetized regions of the unit cell. Our results demonstrate that topographic modification of magnetic thin films opens additional directions for manipulating ferromagnetic resonant excitations.
Feng, Xin; Wu, Shi-Xiang; Zhao, Kun; Wang, Wei; Zhan, Hong-Lei; Jiang, Chen; Xiao, Li-Zhi; Chen, Shao-Hua
2015-11-30
The flow-pattern transition has been a challenging problem in two-phase flow system. We propose the terahertz time-domain spectroscopy (THz-TDS) to investigate the behavior underlying oil-water flow in rectangular horizontal pipes. The low water content (0.03-2.3%) in oil-water flow can be measured accurately and reliably from the relationship between THz peak amplitude and water volume fraction. In addition, we obtain the flow pattern transition boundaries in terms of flow rates. The critical flow rate Qc of the flow pattern transitions decreases from 0.32 m3 h to 0.18 m3 h when the corresponding water content increases from 0.03% to 2.3%. These properties render THz-TDS particularly powerful technology for investigating a horizontal oil-water two-phase flow system.
Exchange coupling in permalloy/BiFeO3 heterostructures
Heron, John; Wang, Chen; Carlton, David; Nowakowski, Mark; Gajek, Martin; Awschalom, David; Bokor, Jeff; Ralph, Dan; Ramesh, R.
2010-03-01
BiFeO3 is a ferroelectric and antiferromagnetic multiferroic with the ferroelectric and antiferromagnetic order parameters coupled at room temperature. This coupling results in the reorientation of the ferroelectric and magnetic domains as applied voltages switch the electric polarization. Previous studies using ferromagnet/BiFeO3 heterostructures have shown that the anisotropy of the ferromagnetic layer can be tuned by the ferroelectric domain structure of the BiFeO3 film [1, 2]. The physical mechanism driving this exchange bias with BiFeO3 is still under investigation. We use patterned permalloy structures, with varying aspect ratios, on BiFeO3 thin films to investigate the physics of this interaction. The results of our studies using MFM, PEEM, and MOKE to understand this mechanism as a means to electric field control of magnetic structures will be presented. [4pt] [1] H. Bea et al., Physical Review Letters 100, 017204 (2008).[0pt] [2] L.W. Martin et al., Nanoletters 8, 2050 (2008).
Magnetic structure of cross-shaped permalloy arrays embedded in silicon wafers
International Nuclear Information System (INIS)
Machida, Kenji; Tezuka, Tomoyuki; Yamamoto, Takahiro; Ishibashi, Takayuki; Morishita, Yoshitaka; Koukitu, Akinori; Sato, Katsuaki
2005-01-01
This paper describes the observed magnetic structure and the micromagnetic simulation of cross-shaped, permalloy (Ni 80 Fe 20 ) arrays embedded in silicon wafers. The nano-scale-width, cross-shaped patterns were fabricated using the damascene technique, electron beam lithography, and chemical mechanical polishing. The magnetic poles were observed as two pairs of bright and dark spots at the ends of the crossed-bars using a magnetic force microscope. The force gradient distributions were simulated based on micromagnetic calculations and tip's stray field calculations using the integral equation method. This process of calculation successfully explains the appearance of the poles and complicated spin structure at the crossing region
Mechanism of magnetization enhancement at CoO/permalloy interfaces
Grytsiuk, Sergii
2013-08-12
We investigate the magnetic properties of CoO(111)/permalloy(111) interfaces by ab-initio calculations. We employ a (5 × 5)CoO/(6 × 6)permalloy supercell, to satisfy the ∼5:6 ratio of the lattice constants, and optimize the atomic density near the interface. While experimentally the interface magnetization is 14% higher than in the bulk, we find for the purely O/Co-terminated interface a decrease/increase by 140%/40%, which enables insight into the real interface with partial O deficiency and atomic intermixing. Intermixing between Fe and Ni significantly lowers the total energy, which promotes Fe accumulation at the interface. Since Co-O bonds are energetically favorable, O diffusion into the permalloy is suppressed.
Mechanism of magnetization enhancement at CoO/permalloy interfaces
Grytsyuk, Sergiy; Schwingenschlö gl, Udo
2013-01-01
We investigate the magnetic properties of CoO(111)/permalloy(111) interfaces by ab-initio calculations. We employ a (5 × 5)CoO/(6 × 6)permalloy supercell, to satisfy the ∼5:6 ratio of the lattice constants, and optimize the atomic density near the interface. While experimentally the interface magnetization is 14% higher than in the bulk, we find for the purely O/Co-terminated interface a decrease/increase by 140%/40%, which enables insight into the real interface with partial O deficiency and atomic intermixing. Intermixing between Fe and Ni significantly lowers the total energy, which promotes Fe accumulation at the interface. Since Co-O bonds are energetically favorable, O diffusion into the permalloy is suppressed.
The magnetic properties of powdered and compacted microcrystalline permalloy
International Nuclear Information System (INIS)
Kollar, P.; Oleksakova, D.; Fuezer, J.; Kovac, J.; Roth, S.; Polanski, K.
2007-01-01
The aim of this work is to investigate the magnetic properties of powdered and compacted microcrystalline Ni-Fe (81 wt% of Ni) permalloy. It was found by investigating the influence of mechanical milling on the magnetic properties of powder samples prepared by milling of the ribbon that the alloy remains a solid solution with stable structure during the whole milling process. With decreasing particle size the rotation of magnetization vector gradually becomes dominant magnetization process and thus coercivity increases. After compaction of the powder by uniaxial hot pressing the magnetic contact between powder particles is recreated and for resulting bulk the displacement of the domain walls becomes dominant magnetization process with coercivity of 11 A/m (comparable with the coercivity of conventional permalloy)
Directory of Open Access Journals (Sweden)
B. V. Chubarenko
Full Text Available We study how a coastal obstruction (peninsula or coastal island affects the three-dimensional barotropic currents in an oblong rectangular basin with variable bathymetry across the basin width. The transverse depth profile is asymmetric and the peninsula or island lies in the middle of the long side of the rectangle. A semi-spectral model for the Boussinesq-approximated shallow water equations, developed in Haidvogel et al. and altered for semi-implicit numerical integration in time in Wang and Hutter, is used to find the steady barotropic state circulation pattern to external winds. The structural (qualitative rearrangements and quanti2tative features of the current pattern are studied under four principal wind directions and different lengths of the peninsula and its inclination relative to the shore. The essentially non-linear relationships of the water flux between the two sub-basins (formed by the obstructing peninsula and the corresponding cross-sectional area left open are found and analysed. It is further analysed whether the depth-integrated model, usually adopted by others, is meaningful when applied to the water exchange problems. The flow through the channel narrowing is quantitatively estimated and compared with the three-dimensional results. The dynamics of the vortex structure and the identification of the up-welling/down-welling zones around the obstruction are discussed in detail. The influence of the transformation of the peninsula into a coastal island on the global basin circulation is considered as are the currents in the channel. The geometric and physical reasons for the anisotropy of the current structure which prevail through all obtained solutions are also discussed.
Key words: Oceanography: general (limnology; numerical modeling - Oceanography: physical (currents
Directory of Open Access Journals (Sweden)
B. V. Chubarenko
2000-06-01
Full Text Available We study how a coastal obstruction (peninsula or coastal island affects the three-dimensional barotropic currents in an oblong rectangular basin with variable bathymetry across the basin width. The transverse depth profile is asymmetric and the peninsula or island lies in the middle of the long side of the rectangle. A semi-spectral model for the Boussinesq-approximated shallow water equations, developed in Haidvogel et al. and altered for semi-implicit numerical integration in time in Wang and Hutter, is used to find the steady barotropic state circulation pattern to external winds. The structural (qualitative rearrangements and quanti2tative features of the current pattern are studied under four principal wind directions and different lengths of the peninsula and its inclination relative to the shore. The essentially non-linear relationships of the water flux between the two sub-basins (formed by the obstructing peninsula and the corresponding cross-sectional area left open are found and analysed. It is further analysed whether the depth-integrated model, usually adopted by others, is meaningful when applied to the water exchange problems. The flow through the channel narrowing is quantitatively estimated and compared with the three-dimensional results. The dynamics of the vortex structure and the identification of the up-welling/down-welling zones around the obstruction are discussed in detail. The influence of the transformation of the peninsula into a coastal island on the global basin circulation is considered as are the currents in the channel. The geometric and physical reasons for the anisotropy of the current structure which prevail through all obtained solutions are also discussed.Key words: Oceanography: general (limnology; numerical modeling - Oceanography: physical (currents
Rectangular cartograms: the game
Berg, de M.T.; Nijnatten, van F.S.B.; Speckmann, B.; Verbeek, K.A.B.
2009-01-01
Raisz [3] introduced rectangular cartograms in 1934 as a way of visualizing spatial information, such as population or economic strength, of a set of regions like countries or states. Rectangular cartograms represent geographic regions by rectangles; the positioning and adjacencies of the rectangles
Probing the oxidation kinetics of small permalloy particles
International Nuclear Information System (INIS)
Dong, Xiaolei; Song, Xiao; Yin, Shiliu; Shirolkar, Mandar M.; Li, Ming; Wang, Haiqian
2017-01-01
The oxidation of permalloys is important to apply in a wide range. The oxidation and diffusion mechanisms of small permalloy particles with different Fe content are studied by using thermal gravimetric analysis (TGA) and microstructure characterizations. Fe 2 O 3 /(Ni, Fe) 3 O 4 plays a key role in the morphology evolution and diffusion mechanisms of small NiFe particles upon oxidation. The activation energies of grain boundary diffusion for the NiFe alloys increase from 141 kJ/mol to 208 kJ/mol as the Fe content increases from 0 to ~50 wt%. We have developed a diffusion process resolved temperature programed oxidation (PR-TPO) analysis method. Three diffusion mechanisms have been recognized by using this method: In addition to the grain boundary diffusion and lattice diffusion, our TGA analysis suggests that the phase conversion from Fe 2 O 3 to (Ni, Fe) 3 O 4 induces diffusion change and affects the diffusion process at the intermediate temperature. Relevant oxidation kinetics and diffusion mechanisms are discussed. - Graphical abstract: The oxidation mechanisms of small Permalloy particles with different Fe content is studied by using thermal gravimetric analysis (TGA) and microstructure characterizations. The activation energies of grain boundary diffusion for the NiFe alloys increases from 140 kJ/mol to 208 kJ/mol as the Fe content increases from 0 to 50 wt% as determined by TGA. We have developed a diffusion process resolved temperature programed oxidation (DPR-TPO) analysis method, and three diffusion mechanisms have been recognized by using this method: In addition to the well-known grain boundary diffusion and lattice diffusion, we found that the phase conversion from Fe 2 O 3 to (Ni, Fe) 3 O 4 will induce diffusion changes and affect the diffusion process at the intermediate temperature. The diffusion processes can be characterized by the corresponding characteristic peak temperatures in temperature programmed oxidation (TPO) analysis. This work not only
Best connected rectangular arrangements
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Krishnendra Shekhawat
2016-03-01
Full Text Available It can be found quite often in the literature that many well-known architects have employed either the golden rectangle or the Fibonacci rectangle in their works. On contrary, it is rare to find any specific reason for using them so often. Recently, Shekhawat (2015 proved that the golden rectangle and the Fibonacci rectangle are one of the best connected rectangular arrangements and this may be one of the reasons for their high presence in architectural designs. In this work we present an algorithm that generates n-4 best connected rectangular arrangements so that the proposed solutions can be further used by architects for their designs.
Vortex dynamics mediated by exchange coupling in permalloy double disks
International Nuclear Information System (INIS)
Liu Yan; Hu Yong; Du An
2012-01-01
The dynamics of magnetic vortices in double disks coupled with a bridge are studied by micromagnetic simulations. There are three types of magnetic configurations being found, which depend on the size of the bridge and the chiralities of the vortices. The exchange coupling between the vortices, which is mediated by the magnetizations in the bridge, influences the trajectories and oscillation frequencies of the vortices. Moreover, the frequency depends on the configurations of the double disks and the bridge size. - Highlights: ► Dynamics of vortices in double Permalloy disks coupled with a bridge are studied. ► Three types of equilibrium configurations are observed for the model. ► Oscillation of the cores depends on the magnetic configuration of the double disks. ► Variation of oscillating frequency with bridge length depends on polarity combination. ► Oscillating frequency decreases with the increasing of the bridge width.
Magnetization configurations and hysteresis loops of small permalloy ellipses
International Nuclear Information System (INIS)
Schneider, M; Liszkowski, J; Rahm, M; Wegscheider, W; Weiss, D; Hoffmann, H; Zweck, J
2003-01-01
We investigated systematically the easy axis magnetization reversal of 20 nm thick permalloy ellipses with a fixed major axis of 1.47 μm and minor axes of 0.22-1.47 μm. Lorentz transmission electron microscopy was used to image the micromagnetic configurations during magnetization reversal. Hysteresis loops of single ellipses were recorded by means of micro-Hall magnetometry and could be traced back to certain reversal mechanisms observed by Lorentz microscopy. In most cases, the magnetization reversal is initiated by the evolution of a magnetization buckling, followed by the formation of a single, a double, or a trapped vortex configuration. For ellipses with high aspect ratio (length-to-width ratio), the magnetization switches in the reversed magnetic field without creation of a stable vortex configuration. Our experiments show that the characteristic field values for vortex creation, single vortex annihilation, and switching strongly depend on the shape anisotropy of the elements
Magnetoresistance of microstructured permalloy ellipses having multi-domain configurations
International Nuclear Information System (INIS)
Kuo, C.Y.; Chung, W.S.; Wu, J.C.; Horng, Lance; Wei, Z.-H.; Lai, M.-F.; Chang, C.-R.
2007-01-01
Mirostructured permalloy ellipses having purposely designed multi-domain configurations were investigated. The samples were fabricated using e-beam lithography through a lift-off process. The magnetoresistance measurements were carried out with a constant dc sensing current under the external magnetic field applied along the short axis. The magnetoresistance curves manifest characteristic features in accordance with the specific domain configurations. Step-like/kink features were observed on the ellipses with cross-tie wall/two-vortex configuration and step-like plus kink magnetorsistance curve was found on the ellipse with cross-tie wall combining with two-vortex structure. A magnetic force microscopy and a micromagnetic simulation were employed to support these results
Magnetoresistance effect in permalloy nanowires with various types of notches
Directory of Open Access Journals (Sweden)
Y. Gao
2018-05-01
Full Text Available Suppressing the stochastic domain wall (DW motion in magnetic nanowires is of great importance for designing DW-related spintronic devices. In this work, we have investigated the pinning/depinning processes of DWs in permalloy nanowires with three different types of notches by using longitudinal magnetoresistance (MR measurement. The averaged MR curves demonstrate that the stochastic DW depinning is suppressed partly or even completely by a transversely asymmetric notch. The single-shot MR curves show that how the resistance changes with the applied field also depends strongly on the notch type while the DW is pinned around the notch. In the case of two depinning fields, larger (smaller change of resistance always corresponds to larger (smaller depinning field, regardless of the notch type. These phenomena can be understood by that the spin structure around the notch changes differently with the notch type when the DW is traveling through the notch.
Magnetic properties of sputtered Permalloy/molybdenum multilayers
International Nuclear Information System (INIS)
Romera, M.; Ciudad, D.; Maicas, M.; Aroca, C.; Ranchal, R.
2011-01-01
In this work, we report the magnetic properties of sputtered Permalloy (Py: Ni 80 Fe 20 )/molybdenum (Mo) multilayer thin films. We show that it is possible to maintain a low coercivity and a high permeability in thick sputtered Py films when reducing the out-of-plane component of the anisotropy by inserting thin film spacers of a non-magnetic material like Mo. For these kind of multilayers, we have found coercivities which are close to those for single layer films with no out-of-plane anisotropy. The coercivity is also dependent on the number of layers exhibiting a minimum value when each single Py layer has a thickness close to the transition thickness between Neel and Bloch domain walls.
Magnetoresistance effect in permalloy nanowires with various types of notches
Gao, Y.; You, B.; Wang, J.; Yuan, Y.; Wei, L. J.; Tu, H. Q.; Zhang, W.; Du, J.
2018-05-01
Suppressing the stochastic domain wall (DW) motion in magnetic nanowires is of great importance for designing DW-related spintronic devices. In this work, we have investigated the pinning/depinning processes of DWs in permalloy nanowires with three different types of notches by using longitudinal magnetoresistance (MR) measurement. The averaged MR curves demonstrate that the stochastic DW depinning is suppressed partly or even completely by a transversely asymmetric notch. The single-shot MR curves show that how the resistance changes with the applied field also depends strongly on the notch type while the DW is pinned around the notch. In the case of two depinning fields, larger (smaller) change of resistance always corresponds to larger (smaller) depinning field, regardless of the notch type. These phenomena can be understood by that the spin structure around the notch changes differently with the notch type when the DW is traveling through the notch.
International Nuclear Information System (INIS)
Frainer, V.J.
1979-01-01
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 800 0 C 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) [pt
Experiences with rectangular waveguide
International Nuclear Information System (INIS)
Beltran, J.; Sepulveda, J. J.; Navarro, E. A.
2000-01-01
A simple and didactic experimental arrangement is presented to show wave propagation along a structure with translational symmetry, particularly the rectangular waveguide. Parameters of this waveguide as cutoff frequency, guide wavelength and field distribution of fundamental mode can be measured. For this purpose a large paralelepipedical waveguide structure is designed and built, its dimensions can be varied in order to change its parameters. (Author) 9 refs
Liu, Haoliang; McLaughlin, Ryan; Sun, Dali; Valy Vardeny, Z.
2018-04-01
Coupling of spins and phonons in ferromagnets (FM) may persist up to mm length scale, thus generating macroscopic spatially distributed spin accumulation along the direction of an applied thermal gradient to an FM slab. This typical feature of transverse spin Seebeck effect (TSSE) has been demonstrated so far using electrical detection methods in FM films, in particular in a patterned structure, in which FM stripes grown onto a substrate perpendicular to the applied thermal gradient direction are electrically and magnetically isolated. Here we report optically detected TSSE response in isolated FM stripes based on permalloy deposited on SiN substrate, upon the application of a thermal gradient. For these measurements we used the magneto-optic Kerr effect measured by an ultrasensitive Sagnac interferometer microscope that is immune to thermo-electrics artefacts. We found that the optical TSSE coefficient in the NiFe stripes geometry is about one order of magnitude smaller than that in the continuous NiFe film, which is due to the limited phonons path in the FM stripes along the thermal gradient direction. Our results further confirm the existence of TSSE response in conducting FM compounds.
International Nuclear Information System (INIS)
Prakash, Tushara; Williams, Grant V.M.; Kennedy, John; Murmu, Peter P.; Leveneur, Jérôme; Chong, Shen V.; Rubanov, Sergey
2014-01-01
Highlights: • New method of arc discharge used to synthesise permalloy containing nanoparticles. • The highest quality powders were made using a 78% Ni permalloy rod in N 2 . • The Saturation moment was slightly less and the coercive field was low (3 mT). • MR contributions from the spin-dependent tunneling between the particles. - Abstract: We report the synthesis of permalloy powders that were made using an arc-discharge method and with 78% or 45% Ni concentrations in N 2 or Ar. Our research was motivated by the fact that magnetic nanoparticles displaying large magnetoresistances are useful for magnetic field sensors applications. The permalloy powders contained some nanoparticles and the particle sizes ranged from 10 nm to ∼20 μm. The highest quality powders were made using a 78% Ni permalloy rod in N 2 where the coercivity was low (0.3 mT) and the saturation moment per formula unit was slightly less than that expected for the bulk compound. Magnetoresistance was observed in a cold pressed pellet where it is likely to be dominated by the ordinary magnetoresistance and spin-dependent tunneling between the particles
Domain configuration and magnetization switching in arrays of permalloy nanostripes
International Nuclear Information System (INIS)
Iglesias-Freire, Ó.; Jaafar, M.; Pérez, L.; Abril, O. de; Vázquez, M.; Asenjo, A.
2014-01-01
The proximity effect in the collective behavior of arrays of magnetic nanostripes is currently a subject of intensive research. The imperative of reducing the size and distances between elements in order to achieve higher storage capacity, faster access to the information as well as low energy consumption, brings consequences about the isolated behavior of the elements and devices. Parallel to each other permalloy nanostripes with high aspect ratio have been prepared by the nanolithography technique. The evolution of the closure domains and the magnetization direction in individual nanostructures has been imaged under applied magnetic fields using Variable Field Magnetic Force Microscopy. Moreover, the magnetostatic interactions between neighboring elements and the proximity effects in arrays of such nanostructures have been quantitatively analyzed by Magnetic Force Microscopy and micromagnetic simulations. The agreement between simulations and the experimental results allows us to conclude the relevance of those interactions depending on the geometry characteristics. In particular, results suggest that the magnetostatic coupling between adjacent nanostripes vanishes for separation distances higher than 500 nm. - Highlights: • A shape anisotropy-induced single domain remanent state is present in the stripes. Closure domains are formed under external fields. • Separation distances between neighboring stripes (500 nm) are enough to overcome the magnetostatic coupling and avoid a multi-stripe character. • Micromagnetic simulations predict critical distances of around 500 nm for the onset of magnetostatic coupling between neighboring elements. • Simulations predict stripes with a small longitudinal separation to behave as single elements, with domain walls “jumping” between them
Domain configuration and magnetization switching in arrays of permalloy nanostripes
Energy Technology Data Exchange (ETDEWEB)
Iglesias-Freire, Ó., E-mail: aasenjo@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, Madrid 28049 (Spain); Jaafar, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, Madrid 28049 (Spain); Dpto. Física de la Materia Condensada, Universidad Autónoma de Madrid, Cantoblanco 28049 (Spain); Pérez, L. [Dpto. Física de Materiales, Universidad Complutense de Madrid, Madrid 28040 (Spain); Abril, O. de [Dpto. Física e Instalaciones Aplicadas a la Edificación, al Medio Ambiente y al Urbanismo, Universidad Politécnica de Madrid, Madrid 28040 (Spain); Vázquez, M.; Asenjo, A. [Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, Madrid 28049 (Spain)
2014-04-15
The proximity effect in the collective behavior of arrays of magnetic nanostripes is currently a subject of intensive research. The imperative of reducing the size and distances between elements in order to achieve higher storage capacity, faster access to the information as well as low energy consumption, brings consequences about the isolated behavior of the elements and devices. Parallel to each other permalloy nanostripes with high aspect ratio have been prepared by the nanolithography technique. The evolution of the closure domains and the magnetization direction in individual nanostructures has been imaged under applied magnetic fields using Variable Field Magnetic Force Microscopy. Moreover, the magnetostatic interactions between neighboring elements and the proximity effects in arrays of such nanostructures have been quantitatively analyzed by Magnetic Force Microscopy and micromagnetic simulations. The agreement between simulations and the experimental results allows us to conclude the relevance of those interactions depending on the geometry characteristics. In particular, results suggest that the magnetostatic coupling between adjacent nanostripes vanishes for separation distances higher than 500 nm. - Highlights: • A shape anisotropy-induced single domain remanent state is present in the stripes. Closure domains are formed under external fields. • Separation distances between neighboring stripes (500 nm) are enough to overcome the magnetostatic coupling and avoid a multi-stripe character. • Micromagnetic simulations predict critical distances of around 500 nm for the onset of magnetostatic coupling between neighboring elements. • Simulations predict stripes with a small longitudinal separation to behave as single elements, with domain walls “jumping” between them.
Annealing effects in plated-wire memory elements. I - Interdiffusion of copper and Permalloy.
Knudson, C. I.; Kench, J. R.
1971-01-01
Results of investigations using X-ray diffraction and electron-beam microprobe techniques have shown that copper and Permalloy platings interdiffuse at low temperatures when plated-wire memory elements are annealed for times as short as 50 hr. Measurable interdiffusion between Permalloy platings and gold substrates does not occur in similar conditions. Both magnetic and compositional changes during aging are found to occur by a thermally activated process with activation energies around 38 kcal/mol. It is shown, however, that copper-diffusion and magnetic-dispersion changes during aging are merely concurrent processes, neither being the other's cause.
Rhometal interface in pseudo-core shell powders like Permalloy/Rhometal type
Energy Technology Data Exchange (ETDEWEB)
Chicinaş, I.; Marinca, T.F.; Popa, F.; Neamţu, B.V.
2015-12-15
Highlights: • Pseudo-core shell powders like Permalloy/Rhometal type obtained by microalloying. • During annealing, by interdiffusion, Rhometal phase is formed at the interface. • Both bcc and fcc structures of the Rhometal have been evidenced in interface. - Abstract: The nanocrystalline Ni{sub 3}Fe (around Permalloy composition) powders were prepared by dry mechanical alloying. The nanocrystalline Ni{sub 3}Fe and carbonyl Fe mixture powders and green compacts have been subjected to heat treatments in an argon atmosphere in order to obtain pseudo-core-shell like particles by micro-alloying in the temperature range of 400–900 °C. The large Permalloy particles are partially covered by very small Fe particles and at the interface a layer of Rhometal is formed by micro-alloying. The Permalloy particles remain in the nanocrystalline/nanostructured state after the annealing independent on the annealing temperature up to 900 °C. Structural, microstructural characterisation and local elemental chemical analysis have been performed by X-ray diffraction, scanning electron microscopy and X-ray microanalysis. The Rhometal interface was studied and evidenced by Fe and Ni concentration profile (EDX microanalysis) and X-ray diffraction. It was found that by a heat treatment up to 900 °C the interface is in the iron zone and at the heat treatment temperature of 900 °C the interface is in both Permalloy and iron zones. By XRD the bcc and fcc structures of the Rhometal have been evidenced. The interface length in iron zones is about 0.8 μm for the heat treatment at 400 °C and reaches 2.5 μm for heat treatment at 900 °C. The interface reaches 10 μm for a temperature of a heat treatment of 900 °C. The iron zones welded by Permalloy zones is evidenced the presence of the Ni atoms up to 4.7 at%. Also, in Permalloy particles are evidenced two zones with a different amount of Ni: one around Ni{sub 0.6}Fe{sub 0.4} composition close to the interface and the second in the
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.
International Nuclear Information System (INIS)
Li, Xiaoyu; Sun, Xiaojun; Wang, Jianbo; Liu, Qingfang
2015-01-01
In this work, the influence of obliquely sputtered Cu underlayer of 10 nm on the magnetic properties of normally sputtered Permalloy thin films with different thicknesses from 10 nm to 150 nm has been investigated. It has been found that the samples with the Permalloy layer thickness ranging from 10 nm to 70 nm exhibit a good in-plane uniaxial magnetic anisotropy, and the increase of the film thickness leads to a decrease of the anisotropy field and the natural resonance frequency. The critical Permalloy layer thickness for stripe domain initiation of these films is about 80 nm, which is thinner than that of obliquely sputtered Permalloy thin films without an underlayer. The characteristic shapes of hysteresis loops which can be called ''transcritical'' are observed above the critical thickness. The condition and mechanism of appearing stripe domain structure were discussed and it has been found that the frequency response of permeability of the anisotropic films shows the characteristics of multi-peak resonance. - Highlights: • Py films were fabricated on obliquely sputtered Cu underlayers by RF magnetron sputtering. • Effects of Py layer thickness on anisotropy, ferromagnetic resonance frequency have been studied. • Samples with Py layer (<70 nm) show a good in-plane uniaxial magnetic anisotropy. • Samples with Py layer (>80 nm) show stripe domains and multi-peaks in permeability spectra
Crystal structure and magnetic properties of UO.sub.2./sub./permalloy thin films
Czech Academy of Sciences Publication Activity Database
Tereshina, Evgeniya; Daniš, S.; Springell, R.; Bao, Z.; Havela, L.; Caciuffo, R.
2015-01-01
Roč. 591, Sep (2015), s. 271-275 ISSN 0040-6090 R&D Projects: GA ČR GP13-25866P Institutional support: RVO:68378271 Keywords : exchange bias * permalloy * uranium dioxide Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.761, year: 2015
Magnetic anisotropy in a permalloy microgrid fabricated by near-field optical lithography
International Nuclear Information System (INIS)
Li, S. P.; Lebib, A.; Peyrade, D.; Natali, M.; Chen, Y.; Lew, W. S.; Bland, J. A. C.
2001-01-01
We report the fabrication and magnetic properties of permalloy microgrids prepared by near-field optical lithography and characterized using high-sensitivity magneto-optical Kerr effect techniques. A fourfold magnetic anisotropy induced by the grid architecture is identified. [copyright] 2001 American Institute of Physics
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.
Ferromagnetic resonance in coupled permalloy double films separated by a Cu interlayer
Maksymowicz, A. Z.; Whiting, J. S. S.; Watson, M. L.; Chambers, A.
1991-03-01
Ferromagnetic resonance (FMR) at 16 GHz was used to study the magnetic coupling between two-layers of permalloy separated by a nonmagnetic Cu layer. Samples with the same thickness (600 Å) of both permalloy layers were deposited from e-gun sources onto glass substrates in UHV. The thickness d of the Cu interlayer was varied from 5 to 37 Å. The exchange coupling energy ( E = - KM1· M2) model was used to describe the interaction between the two magnetic layers. It was found from the ferromagnetic resonance data in the perpendicular configuration that K( d) follows an exponential law, K = K0e - d/ q, where q = 9.3 Å.
Spin glass transition in a thin-film NiO/permalloy bilayer
Ma, Tianyu; Urazhdin, Sergei
2018-02-01
We experimentally study magnetization aging in a thin-film NiO/permalloy bilayer. Aging characteristics are nearly independent of temperature below the exchange bias blocking temperature TB, but rapidly vary above it. The dependence on the magnetic history qualitatively changes across TB. The observed behaviors are consistent with the spin glass transition at TB, with significant implications for magnetism and magnetoelectronic phenomena in antiferromagnet/ferromagnet bilayers.
Curie temperatures of fcc and bcc Nickel and Permalloy: Supercell and Green's function methods
Czech Academy of Sciences Publication Activity Database
Yu, P.; Jin, X.F.; Kudrnovský, Josef; Wang, D. S.; Bruno, P.
2008-01-01
Roč. 77, č. 5 (2008), 054431/1-054431/8 ISSN 1098-0121 R&D Projects: GA MŠk OC 150; GA AV ČR IAA100100616 Institutional research plan: CEZ:AV0Z10100520 Keywords : fcc - and bcc-Ni * Permalloy * magnetic moments * Curie temperatures Subject RIV: BE - Theoretical Physics Impact factor: 3.322, year: 2008
Fabrication and physical properties of permalloy nano-size wires
International Nuclear Information System (INIS)
Yu, C.; Lee, S.F.; Yao, Y.D.; Wong, M.S.; Huang, E.W.; Ma, Y.-R.; Tsai, J.L.; Chang, C.R.
2003-01-01
Nano-size NiFe wires with patterned shapes in half-ring-in-series, octagon-in-series, and zigzag-in-series configurations were fabricated. Their magnetoresistance was studied below room temperature and their magnetic domain images were investigated at room temperature by a magnetic force microscope. In general, we have experimentally demonstrated that the variation of the magnetoresistance of our patterned nano-size wires can be related to different domain configurations and explained by the domain switching effect. The number of magnetic domain walls in our patterned wires can be controlled by the shape anisotropy and the size of each section of patterns that form the wires
On Hubbell's rectangular source integral
International Nuclear Information System (INIS)
Stalker, John
2001-01-01
The integral H(a,b)=∫ 0 b ∫ 0 a dx dy/(1+x 2 +y 2 ) arises naturally in the study of radiation from a rectangular source and has been studied by many authors. This paper introduces a new series expansion which is rapidly convergent for large a and b
Time-resolved magnetization dynamics of cross-tie domain walls in permalloy microstructures
International Nuclear Information System (INIS)
Miguel, J; Kurde, J; Piantek, M; Kuch, W; Sanchez-Barriga, J; Heitkamp, B; Kronast, F; Duerr, H A; Bayer, D; Aeschlimann, M
2009-01-01
We report on a picosecond time-resolved x-ray magnetic circular dichroic-photoelectron emission microscopy study of the evolution of the magnetization components of a microstructured permalloy platelet comprising three cross-tie domain walls. A laser-excited photoswitch has been used to apply a triangular 80 Oe, 160 ps magnetic pulse. Micromagnetic calculations agree well with the experimental results, both in time and frequency, illustrating the large angle precession in the magnetic domains with magnetization perpendicular to the applied pulse, and showing how the magnetic vortices revert their core magnetization while the antivortices remain unaffected.
Time-resolved magnetization dynamics of cross-tie domain walls in permalloy microstructures
Energy Technology Data Exchange (ETDEWEB)
Miguel, J; Kurde, J; Piantek, M; Kuch, W [Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin (Germany); Sanchez-Barriga, J; Heitkamp, B; Kronast, F; Duerr, H A [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin (Germany); Bayer, D; Aeschlimann, M, E-mail: jorge.miguel@fu-berlin.d [Fachbereich Physik, Universitaet Kaiserslautern, Erwin-Schroedinger Strasse 46, D-67663 Kaiserslautern (Germany)
2009-12-02
We report on a picosecond time-resolved x-ray magnetic circular dichroic-photoelectron emission microscopy study of the evolution of the magnetization components of a microstructured permalloy platelet comprising three cross-tie domain walls. A laser-excited photoswitch has been used to apply a triangular 80 Oe, 160 ps magnetic pulse. Micromagnetic calculations agree well with the experimental results, both in time and frequency, illustrating the large angle precession in the magnetic domains with magnetization perpendicular to the applied pulse, and showing how the magnetic vortices revert their core magnetization while the antivortices remain unaffected.
Understanding stripe domains in Permalloy films via the angular dependence of permeability spectra
Energy Technology Data Exchange (ETDEWEB)
Wei, Jinwu; Feng, Hongmei; Zhu, Zengtai; Song, Chengkun; Wang, Xiangqian; Liu, Qingfang [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Wang, Jianbo, E-mail: wangjb@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Key Laboratory for Special Function Materials and Structural Design of the Ministry of the Education, Lanzhou University, Lanzhou 730000 (China)
2017-06-15
Highlights: • A phenomenological model is proposed to analyze the angular dependence of the μ″{sub max}. • The maximum canting angle θ{sub 0} in the stripe domain structure can be estimated. • Micromagnetic simulation results are nearly in accordance with the experimental results. - Abstract: An investigation of the angular dependence of the dynamic permeability spectra has been performed. Three Permalloy films with different thickness were used as the study samples that possess the stripe domains. In order to better understand the magnetization distribution in stripe domains, a theoretical approach was proposed to analyze the variation of the resonance intensity of permeability spectra. By fitting the angular dependence of the μ″{sub max} using a theoretical function, a coefficient Λ that can be used to evaluate the average value of the periodic function of the anting angle θ in a periodic stripe is obtained. As the film thickness increases, the decrease of the ratio between domain wall width and stripe domain width is happen. This enables that the coefficient Λ decreases with the increase of film thickness. By deducing this coefficient Λ, one can estimate the maximum canting angle θ{sub 0} ∼ 8° for the Permalloy films in our experiments.
Motion of rectangular prismatic bodies
International Nuclear Information System (INIS)
Poreh, M.; Wray, R.N.
1979-01-01
Rectangular prismatic bodies can assume either a translatory or an auto-rotating mode of motion during free motion in the atmosphere. The translatory mode is stable only when the dimensionless moment of inertia of the bodies is large, however, large perturbations will always start auto-rotation. The characteristics of the auto-rotational mode are shown to depend primarily on the aspect ratio of the bodies which determines the dimensionless rotational speed and the lift coefficient. Both the average drag and lift-coefficients of auto-rotating bodies are estimated, but it is shown that secondary effects make it impossible to determine their exact trajectories in atmospheric flows
International Nuclear Information System (INIS)
Lim, K.M.; Park, S.Y.; Namkung, J.; Kim, M.C.; Park, C.G.
2007-01-01
The effects of Si addition on microstructure and magnetic properties of permalloy strips fabricated by the melt drag casting method were investigated. Permalloy strips with 200 mm width were successfully fabricated by melt drag casting followed by homogenizing, cold rolling and annealing. In order to understand the relationship between microstructure and magnetic properties, we measured permeability and analyzed microstructure as a function of Si content by optical microscopy, X-ray diffraction and transmission electron microscopy. The effective permeability went through a maximum value in 2 at.% Si added permalloy strips and then decreased with increasing Si content. Increasing Si content enlarged grain size, which resulted in improvement of permeability. Permalloy strips with 5 at.% Si, however, showed drastically reduced permeability than that of 2 at.% Si added ones notwithstanding their coarse grain size and little oxide inclusion. The degradation of permeability in over-added Si above 2 at.% could be explained by formation of Ni 3 Fe ordered phase, which increase magneto-crystalline anisotropy
Partitioning sparse rectangular matrices for parallel processing
Energy Technology Data Exchange (ETDEWEB)
Kolda, T.G.
1998-05-01
The authors are interested in partitioning sparse rectangular matrices for parallel processing. The partitioning problem has been well-studied in the square symmetric case, but the rectangular problem has received very little attention. They will formalize the rectangular matrix partitioning problem and discuss several methods for solving it. They will extend the spectral partitioning method for symmetric matrices to the rectangular case and compare this method to three new methods -- the alternating partitioning method and two hybrid methods. The hybrid methods will be shown to be best.
Study of gas-water flow in horizontal rectangular channels
Chinnov, E. A.; Ron'shin, F. V.; Kabov, O. A.
2015-09-01
The two-phase flow in the narrow short horizontal rectangular channels 1 millimeter in height was studied experimentally. The features of formation of the two-phase flow were studied in detail. It is shown that with an increase in the channel width, the region of the churn and bubble regimes increases, compressing the area of the jet flow. The areas of the annular and stratified flow patterns vary insignificantly.
Mapping from rectangular to harmonic representation
International Nuclear Information System (INIS)
Schneider, W.; Bateman, G.
1986-08-01
An algorithm is developed to determine the Fourier harmonics representing the level contours of a scalar function given on a rectangular grid. This method is applied to the problem of computing the flux coordinates and flux surface average needed for 1-1/2-D transport codes and MHD stability codes from an equilibrium flux function given on a rectangular grid
Research Update: Spin transfer torques in permalloy on monolayer MoS2
Directory of Open Access Journals (Sweden)
Wei Zhang
2016-03-01
Full Text Available We observe current induced spin transfer torque resonance in permalloy (Py grown on monolayer MoS2. By passing rf current through the Py/MoS2 bilayer, field-like and damping-like torques are induced which excite the ferromagnetic resonance of Py. The signals are detected via a homodyne voltage from anisotropic magnetoresistance of Py. In comparison to other bilayer systems with strong spin-orbit torques, the monolayer MoS2 cannot provide bulk spin Hall effects and thus indicates the purely interfacial nature of the spin transfer torques. Therefore our results indicate the potential of two-dimensional transition-metal dichalcogenide for the use of interfacial spin-orbitronics applications.
International Nuclear Information System (INIS)
Huang, Chong; Yun, Eui-Jung; Ma, James; Keto, John W.; Becker, Michael F.; Kovar, Desiderio
2009-01-01
A permalloy (Ni 81 Fe 19 ; at%) microparticle (MP) aerosol was ablated to produce a nanoparticle (NP) aerosol that was then impacted at high velocity onto a substrate to produce porous thick films. The structure of the NPs was analyzed by transmission electron microscopy and the morphologies of the NPs and the nanostructured films were studied using high-resolution transmission electron microscopy and scanning electron microscopy. These analyses showed that the original composition and structure of the MPs were preserved in the NPs and films. The majority of NPs that were produced ranged in size between 2 and 15 nm with some larger particles present. Magnetization-temperature curves showed that the films consisted of a mixture of small superparamagnetic NPs and larger ferromagnetic NPs. A high saturation magnetization of 62.3 emu/g at 300 K was retained in the films indicating that they remained free of significant oxidation.
Domain walls and exchange-interaction in Permalloy/Gd films
International Nuclear Information System (INIS)
Ranchal, R; Aroca, C; Lopez, E
2008-01-01
In this work we study the exchange coupling in Permalloy (Py)/gadolinium (Gd) bilayers. The exchange-coupled Py/Gd system is very temperature dependent and moreover the magnetization process in the Py layer is mainly due to domain wall (DW) displacements which are strongly controlled by pinning effects. We propose that this pinning could be caused by magnetostatic and exchange interactions between Py DWs and the magnetostrictive Gd layer. These effects mask the antiferromagnetic coupling between layers and, depending on temperature and Py thicknesses, apparent ferromagnetic coupling occurs. The study has been performed in the 80-300 K temperature range for different Py layer thicknesses and different Py induced anisotropies
Energy Technology Data Exchange (ETDEWEB)
Zighem, F; Roussigne, Y; Cherif, S-M; Moch, P [Laboratoire des Proprietes Mecaniques et Thermodynamiques des Materiaux, CNRS UPR 9001, Universite Paris Nord, 93430 Villetaneuse (France); Ben Youssef, J [Laboratoire de Magnetisme de Bretagne, CNRS, Universite de Bretagne Occidentale, 29285 Brest (France); Paumier, F, E-mail: fatih.zighem@cea.f [Institut Pprime, CNRS UPR 3346, Universite de Poitiers, ENSMA, 86962 Futuroscope (France)
2010-10-13
Microstrip ferromagnetic resonance and Brillouin scattering are used to provide a comparative determination of the magnetic parameters of thin permalloy layers interfaced with a non-magnetic (Al{sub 2}O{sub 3}) or with an antiferromagnetic oxide (NiO). It results from our microstructural study that no preferential texture is favoured in the observed polycrystalline sublayers. It is shown that the perpendicular anisotropy can be monitored using an interfacial surface energy term which is practically independent of the nature of the interface. In the interval of thicknesses investigated (5-25 nm) the saturation magnetization does not significantly differ from the reported one in bulk permalloy. In-plane uniaxial anisotropy and exchange bias anisotropy are also derived from the study of the dynamic magnetic excitations and compared with our independent evaluations using conventional magnetometry.
Feinberg, Benedict; Gould, Harvey
2018-03-01
Following the application of an external magnetic field to a thin-walled demagnetized Permalloy cylinder, the magnetic flux density at the center of the shielded volume decreases by roughly 20% over periods of hours to days. We measured this effect for applied magnetic fields from 0.48 A/m to 16 A/m, the latter being comparable to the Earths magnetic field at its weakest point. Delayed changes in magnetic flux density are also observed following alternating current demagnetization. We attribute these effects to delayed changes in magnetization, which have previously been observed in thin Permalloy films and small bulk samples of ferromagnetic materials. Phenomenological models of thermal activation are discussed. Some possible effects on experiments that rely on static shielding are noted.
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.
Ji, Shengxiang; Nagpal, Umang; Liao, Wen; de Pablo, Juan; Nealey, Paul
2010-03-01
Patterns of square and rectangular arrays with nanoscale dimensions are scientifically and technologically important. Fabrication of square array patterns in thin films has been demonstrated by directed assembly of cylinder-forming diblock copolymers on chemically patterned substrates, supramolecular assembly of diblock copolymers, and self-assembly of triblock terpolymers. However, a macroscopic area of square array patterns with long-range order has not been achieved, and the fabrication of rectangular arrays has not been reported so far. Here we report a facile approach for fabricating patterns of square and rectangular arrays by directing the assembly of sphere-forming diblock copolymers on chemically patterned substrates. On stripe patterns, a square arrangement of half spheres, corresponding to the (100) plane of the body-centred cubic (BCC) lattice, formed on film surfaces. When the underlying pattern periods mismatched with the copolymer period, the square pattern could be stretched (up to ˜60%) or compressed (˜15%) to form rectangular arrays. Monte Carlo simulations have been further used to verify the experimental results and the 3-dimensional arrangements of spheres.
Raviolo, Sofía; Tejo, Felipe; Bajales, Noelia; Escrig, Juan
2018-01-01
In this paper we have compared the angular dependence of the magnetic properties of permalloy (Ni80Fe20) and nickel nanowires by means of micromagnetic simulations. For each material we have chosen two diameters, 40 and 100 nm. Permalloy nanowires with smaller diameters (d = 40 nm) exhibit greater coercivity than nickel nanowires, regardless of the angle at which the external magnetic field is applied. In addition, both Py and Ni nanowires exhibit the same remanence values. However, the nanowires of larger diameters (d = 100 nm) exhibit a more complex behavior, noting that for small angles, nickel nanowires are those that now exhibit a greater coercivity in comparison to those of permalloy. The magnetization reversal modes vary as a function of the angle at which the external field is applied. When the field is applied parallel to the wire axis, it reverts through nucleation and propagation of domain walls, whereas when the field is applied perpendicular to the axis, it reverts by a pseudo-coherent rotation. These results may provide a guide to control the magnetic properties of nanowires for use in potential applications.
Energy Technology Data Exchange (ETDEWEB)
Holanda, J., E-mail: joseholanda@df.ufpe.br; Maior, D.S.; Azevedo, A.; Rezende, S.M.
2017-06-15
Highlights: • We have investigated the anisotropic magnetoresistance (AMR) and the anomalous Nernst effect (ANE) in an exchange-biased bilayer Py/(100) NiO single-Crystal. • The shift of the hysteresis loop, measured with the different techniques, yield approximately the same value of H{sub EB}. • In spite of the measurement techniques be based in different physical phenomena, our results confirm the robustness of the exchange anisotropy at the Py/NiO interface. • The strength of the anomalous Nernst effect for the exchange-biased permalloy film is compared to values measured in non biased films. - Abstract: We have investigated the anisotropic magnetoresistance (AMR) and the anomalous Nernst effect (ANE) in an exchange-biased bilayer consisting of a thin film of permalloy deposited on a single crystal antiferromagnetic NiO (1 0 0). The exchange bias field (H{sub EB}) value was obtained by means of AMR, ANE and magnetization hysteresis measurements. The shift of the hysteresis loop, measured with the three different techniques, yield approximately the same value of H{sub EB.} In spite of the measurement techniques be based in different physical phenomena, our results confirm the robustness of the exchange anisotropy at the Py/NiO interface. The strength of the anomalous Nernst effect for the exchange-biased permalloy film is compared to values measured in non biased films.
three dimensional photoelastic investigations on thick rectangular
African Journals Online (AJOL)
user
1983-09-01
Sep 1, 1983 ... Thick rectangular plates are investigated by means of three-dimensional photoelasticity ... a thin plate theory and a higher order thick plate theory. 1. ..... number of fringes lest the accuracy of the results will be considerably.
Rectangular-section mirror light pipes
Energy Technology Data Exchange (ETDEWEB)
Swift, P.D.; Lawlor, R. [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); Smith, G.B.; Gentle, A. [Department of Applied Physics, University of Technology, Sydney, Broadway, NSW 2007 (Australia)
2008-08-15
Using an integrated-ray approach an expression for the transmission of rectangular section mirror light pipe (MLP) has been derived for the case of collimated light input. The transmittance and the irradiance distribution at the exit aperture of rectangular-section MLPs have been measured experimentally and calculated theoretically for the case of collimated light input. The results presented extend the description of MLPs from the cylindrical case. Measured and calculated transmittances and irradiance distributions are in good agreement. (author)
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....
Partial rectangular metric spaces and fixed point theorems.
Shukla, Satish
2014-01-01
The purpose of this paper is to introduce the concept of partial rectangular metric spaces as a generalization of rectangular metric and partial metric spaces. Some properties of partial rectangular metric spaces and some fixed point results for quasitype contraction in partial rectangular metric spaces are proved. Some examples are given to illustrate the observed results.
Magnetically actuated bi-directional microactuators with permalloy and Fe/Pt hard magnet
International Nuclear Information System (INIS)
Pan, C.T.; Shen, S.C.
2005-01-01
Bi-directional polyimide (PI) electromagnetic microactuator with different geometries are designed, fabricated and tested. Fabrication of the electromagnetic microactuator consists of 10 μm thick Ni/Fe (80/20) permalloy deposition on the PI diaphragm by electroplating, high aspect ratio electroplating of copper planar coil with 10 μm in thickness, bulk micromachining, and excimer laser selective ablation. They were fabricated by a novel concept avoiding the etching selectivity and residual stress problems during wafer etching. A mathematical model is created by ANSYS software to analyze the microactuator. The external magnetic field intensity (H ext ) generated by the planar coil is simulated by ANSYS software. ANSYS software is used to predict the deflection angle of the microactuator. Besides, to provide bi-directional and large deflection angle of microactuator, hard magnet Fe/Pt is deposited at a low temperature of 300 deg. C by sputtering onto the PI diaphragm to produce a perpendicular magnetic anisotropic field. This magnetic field can enhance the interaction with H ext to induce attractive and repulsive bi-directional force to provide large displacement. The results of magnetic microactuator with and without hard magnets are compared and discussed. The preliminary result reveals that the electromagnetic microactuator with hard magnet shows a greater deflection angle than that without one
Effects of spacer layer on growth, stress and magnetic properties of sputtered permalloy film
International Nuclear Information System (INIS)
Cheng, S.F.; Lubitz, P.; Zheng, Y.; Edelstein, A.S.
2004-01-01
A microelectromechanical (MEMS) flux concentrator (J. Appl. phys. 91 (2002) 7795), is a device that will minimize 1/f noise in magnetic sensors by modulating the magnetic field at the position of the sensor. This requires high permeability and low stress permalloy (Py) films to be deposited on the MEMS flaps (J. Appl. phys. 91 (2002) 7795). Py (Ni 80 Fe 20 ) films from 100 to 560 nm thick were deposited on Si substrates using DC magnetron sputtering. The effects of deposition conditions on the grain morphology, texture, stress and magnetic properties were studied. Lower sputtering pressure changes film stress from tension to compression and increases the out of film plane texture, while higher power increases tension and texture. Neutral film stress was obtained with 100 W of sputtering power and 1.25 mTorr of Ar gas pressure. With increasing thickness, the Py film was found to develop a stripe-like domain configuration at low fields because of strong out-of-plane magnetic anisotropy. The critical thickness is around 180 nm.This may be explained by a competition between planar demagnetization fields and columnar magnetic anisotropy. Adding 5 nm of Ta or Cr layer as spacer successfully broke up the continuity of the magnetic structure and allowed us to produce high-permeability films by fabricating (Ta/Py) or (Cr/Py) multilayer films with each Py layer thinner than the critical thickness
Epitaxial Growth of Permalloy Thin Films on MgO Single-Crystal Substrates
International Nuclear Information System (INIS)
Ohtake, Mitsuru; Tanaka, Takahiro; Matsubara, Katsuki; Futamoto, Masaaki; Kirino, Fumiyoshi
2011-01-01
Permalloy (Py: Ni - 20 at. % Fe) thin films were prepared on MgO single-crystal substrates of (100), (110), and (111) orientations by molecular beam epitaxy. Py crystals consisting of fcc(100) and hcp(112-bar 0) orientations epitaxially nucleate on MgO(100) substrates. With increasing the substrate temperature, the volume ratio of fcc(100) to hcp(112-bar 0) crystal increases. The metastable hcp(112-bar 0) structure transforms into more stable fcc(110) structure with increasing the film thickness. Py(110) fcc single-crystal films are obtained on MgO(110) substrates, whereas Py films epitaxially grow on MgO(111) substrates with two types of fcc(111) variants whose orientations are rotated around the film normal by 180 deg. each other. X-ray diffraction analysis indicates that the out-of-plane and the in-plane lattice spacings of these fcc-Py films agree within ±0.4% with the values of bulk fcc-Py crystal, suggesting that the strains in the films are very small. High-resolution transmission electron microscopy shows that periodical misfit dislocations are preferentially introduced in the films around the Py/MgO(100) and the Py/MgO(110) interfaces to reduce the lattice mismatches. The magnetic properties are considered to be reflecting the magnetocrystalline anisotropies of bulk fcc-Py and/or metastable hcp-Py crystals and the shape anisotropy caused by the surface undulations.
Epitaxial Growth of Permalloy Thin Films on MgO Single-Crystal Substrates
Energy Technology Data Exchange (ETDEWEB)
Ohtake, Mitsuru; Tanaka, Takahiro; Matsubara, Katsuki; Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi, E-mail: ohtake@futamoto.elect.chuo-u.ac.jp [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan)
2011-07-06
Permalloy (Py: Ni - 20 at. % Fe) thin films were prepared on MgO single-crystal substrates of (100), (110), and (111) orientations by molecular beam epitaxy. Py crystals consisting of fcc(100) and hcp(112-bar 0) orientations epitaxially nucleate on MgO(100) substrates. With increasing the substrate temperature, the volume ratio of fcc(100) to hcp(112-bar 0) crystal increases. The metastable hcp(112-bar 0) structure transforms into more stable fcc(110) structure with increasing the film thickness. Py(110){sub fcc} single-crystal films are obtained on MgO(110) substrates, whereas Py films epitaxially grow on MgO(111) substrates with two types of fcc(111) variants whose orientations are rotated around the film normal by 180 deg. each other. X-ray diffraction analysis indicates that the out-of-plane and the in-plane lattice spacings of these fcc-Py films agree within {+-}0.4% with the values of bulk fcc-Py crystal, suggesting that the strains in the films are very small. High-resolution transmission electron microscopy shows that periodical misfit dislocations are preferentially introduced in the films around the Py/MgO(100) and the Py/MgO(110) interfaces to reduce the lattice mismatches. The magnetic properties are considered to be reflecting the magnetocrystalline anisotropies of bulk fcc-Py and/or metastable hcp-Py crystals and the shape anisotropy caused by the surface undulations.
Frequency and temperature dependence of ferromagnetic linewidth in exchange biased Permalloy
International Nuclear Information System (INIS)
Lubitz, P.; Rubinstein, M.; Krebs, J. J.; Cheng, S.-F.
2001-01-01
Ferromagnetic resonance linewidths were measured at 9.5 and 35 GHz and in the temperature range from 77 to 350 K for thin Permalloy (Py) films exchange biased by adjacent layers of NiO, CoO, or IrMn. Compared to unoxidized Py alone, for which the linewidth is nearly temperature independent in this range and scales linearly with frequency, exchange biased Py has broader lines with distinctive temperature dependences for each bias material at 9.5 GHz. Different temperature dependences were observed at 35 GHz. Our results are consistent with relaxation related to thermally driven reversal of the antiferromagnetic grains. Intrinsic damping and inhomogeneities also add to the widths. The qualitative features of the temperature and frequency dependences of the linewidths can be described with the usual expression for the slow relaxation linewidth mechanism. The temperature dependence of the relaxation time is taken from Neel's expression for the reversal time using appropriate rate prefactors and activation energies. [copyright] 2001 American Institute of Physics
Studies of magnetic properties of permalloy (Fe-30%Ni) prepared by SLM technology
International Nuclear Information System (INIS)
Zhang Baicheng; Fenineche, Nour-Eddine; Zhu Lin; Liao Hanlin; Coddet, Christian
2012-01-01
In the present study, a high permeability induction Fe-30%Ni alloy cubic bulk was prepared by the selective laser melting process. In order to reveal the microstructure effect on soft magnetic properties, the microstructure and magnetic properties of the Fe-30%Ni alloy were carefully investigated by scanning electron microscopy, X-ray diffraction and hysteresis measurements. The bcc-Fe (Ni) phase formation is identified by X-ray diffraction. Meanwhile, it was found that low bcc lattice parameter and high grain size could be obtained when high laser scanning velocity and low laser power were used. Moreover, the lowest value of coercivity is 88 A/m, and the highest value of saturation magnetization is 565 Am 2 /kg, which can be obtained at a low laser scanning velocity of 0.4 m/s and high laser power input at 110 W. - Highlights: → Proper Fe-30%Ni alloy (permalloy) using selective laser melting technology. → Microstructure of Fe-30%Ni alloy exhibits fine cellular structure of approximately 100 nm. → Magnetic properties can be controlled by laser parameter. → Lowest coercivity is 88 A/m and highest saturation magnetization is 565 Am 2 /kg.
Numerical investigation of flow past a row of rectangular rods
Directory of Open Access Journals (Sweden)
S.Ul. Islam
2016-09-01
Full Text Available A numerical study of uniform flow past a row of rectangular rods with aspect ratio defined as R = width/height = 0.5 is performed using the Lattice Boltzmann method. For this study the Reynolds number (Re is fixed at 150, while spacings between the rods (g are taken in the range from 1 to 6. Depending on g, the flow is classified into four patterns: flip-flopping, nearly unsteady-inphase, modulated inphase-antiphase non-synchronized and synchronized. Sudden jumps in physical parameters were observed, attaining either maximum or minimum values, with the change in flow patterns. The mean drag coefficient (Cdmean of middle rod is higher than the second and fourth rod for flip-flopping pattern while in case of nearly unsteady-inphase the middle rod attains minimum drag coefficient. It is also found that the Strouhal number (St of first, second and fifth rod decreases as g increases while that of other two have mixed trend. The results further show that there exist secondary interaction frequencies together with primary vortex shedding frequency due to jet in the gap between rods for 1 ⩽ g ⩽ 3. For the average values of Cdmean and St, an empirical relation is also given as a function of gap spacing. This relation shows that the average values of Cdmean and St approach to those of single rectangular rod with increment in g.
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.
Hirayama, Shigeyuki; Mitani, Seiji; Otani, YoshiChika; Kasai, Shinya
2018-06-01
We examined the spin-Hall-induced spin torque ferromagnetic resonance (ST-FMR) in platinum/permalloy bilayer thin films under bias direct current (DC). The bias DC modulated the symmetric components of the ST-FMR spectra, while no dominant modulation was found in the antisymmetric components. A detailed analysis in combination with simple model calculations clarified that the major origin of the modulation can be attributed to the DC resistance change under the precessional motion of magnetization. This effect is the second order contribution for the precession angle, even though the contribution can be comparable to the rectification voltage under some specific conditions.
International Nuclear Information System (INIS)
Kuril'chik, E.V.; Pavlov, P.V.; Pavlov, A.P.; Tetel'baum, D.I.
1992-01-01
It has been found that a change in microdistorsions and in a number of properties (coercive force, microhardness, friction coefficient) in Fe, Ni films as well as in rolled permalloy foils nonmonotonically depends on the ion irradiation dose. Such a behaviour of the dose dependence is explained by the competition of three mechanisms of the change in the spatial inhomogeneity (relief) of elastic stresses: formation of complexes impurity - intrinsic interstitial atom in the atmosphere of extended defects; separation of vacancies and interstitial atoms by the fields of elastic stresses; formation of precipitates of chemical compounds. The long-range action effect was revealed at irradiation of foils
Energy Technology Data Exchange (ETDEWEB)
Kononov, A.; Egorov, S. V. [Russian Academy Sciences, Institute of Solid State Physics (Russian Federation); Kvon, Z. D.; Mikhailov, N. N.; Dvoretsky, S. A. [Institute of Semiconductor Physics (Russian Federation); Deviatov, E. V., E-mail: dev@issp.ac.ru [Russian Academy Sciences, Institute of Solid State Physics (Russian Federation)
2016-11-15
We experimentally investigate spin-polarized electron transport between a permalloy ferromagnet and the edge of a two-dimensional electron system with band inversion, realized in a narrow, 8 nm wide, HgTe quantum well. In zero magnetic field, we observe strong asymmetry of the edge potential distribution with respect to the ferromagnetic ground lead. This result indicates that the helical edge channel, specific for the structures with band inversion even at the conductive bulk, is strongly coupled to the ferromagnetic side contact, possibly due to the effects of proximity magnetization. This allows selective and spin-sensitive contacting of helical edge states.
Energy Technology Data Exchange (ETDEWEB)
Peng, Y. [College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610066 (China); College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Zhao, G.P., E-mail: zhaogp@uestc.edu.cn [College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610066 (China); Morvan, F.J.; Wu, S.Q. [College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610066 (China); Yue, M. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China)
2017-01-15
Due to its potential applications in high-density magnetic storage and spin electronic devices, the ferromagnetic resonance absorption phenomenon has recently drawn much attention. By studying the influence of different materials with various shapes on this phenomenon, the new understandings gained could lead to other applications in the future. In this paper, dynamic magnetic susceptibilities of the vortex state in permalloy nanodot arrays have been investigated using a three-dimensional object oriented micromagnetic framework (OOMMF) code with a two-dimensional periodic boundary condition (2D-PBC) extension and compared with those of a single dot carefully. The resonance mode is excited in the vortex state of nanodot arrays by the microwave magnetic field perpendicular to the dot plane. In this case only radially symmetric spin wave modes can be excited. The influence of the geometric parameters on the resonance frequency has been studied systemically, including the dot radius, the number of repeating elements, and the dot distance. One can see that the resonance peak of the dot array is higher than that of a single dot because of the induced stronger magnetostatic coupling. A critical dot distance exists at which the dot array may be treated as a single dot. There is only one resonance peak for both the dot array and the single dot, as the radius changes. - Highlights: • Resonance peak of the dot array is higher than that of a single dot because of the induced stronger magnetostatic coupling. • A critical dot distance exists at which the dot array may be treated as a single dot. • There is only one resonance peak for both the dot array and the single dot, as the radius changes.
International Nuclear Information System (INIS)
Peng, Y.; Zhao, G.P.; Morvan, F.J.; Wu, S.Q.; Yue, M.
2017-01-01
Due to its potential applications in high-density magnetic storage and spin electronic devices, the ferromagnetic resonance absorption phenomenon has recently drawn much attention. By studying the influence of different materials with various shapes on this phenomenon, the new understandings gained could lead to other applications in the future. In this paper, dynamic magnetic susceptibilities of the vortex state in permalloy nanodot arrays have been investigated using a three-dimensional object oriented micromagnetic framework (OOMMF) code with a two-dimensional periodic boundary condition (2D-PBC) extension and compared with those of a single dot carefully. The resonance mode is excited in the vortex state of nanodot arrays by the microwave magnetic field perpendicular to the dot plane. In this case only radially symmetric spin wave modes can be excited. The influence of the geometric parameters on the resonance frequency has been studied systemically, including the dot radius, the number of repeating elements, and the dot distance. One can see that the resonance peak of the dot array is higher than that of a single dot because of the induced stronger magnetostatic coupling. A critical dot distance exists at which the dot array may be treated as a single dot. There is only one resonance peak for both the dot array and the single dot, as the radius changes. - Highlights: • Resonance peak of the dot array is higher than that of a single dot because of the induced stronger magnetostatic coupling. • A critical dot distance exists at which the dot array may be treated as a single dot. • There is only one resonance peak for both the dot array and the single dot, as the radius changes.
Study on the coherence degree of magnetization reversal in Permalloy single-domain nano-ellipses
Energy Technology Data Exchange (ETDEWEB)
Júnior, D.S. Vieira [Departamento Acadêmico de Matemática, Física, e Estatística, Instituto Federal de Educação, Ciência e Tecnologia do Sudeste de Minas Gerais – Campus Rio Pomba, Rio Pomba, Minas Gerais 36180-000 (Brazil); Leonel, S.A. [Departamento de Física, Laboratório de Simulação Computacional, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais 36036-330 (Brazil); Toscano, D., E-mail: danilotoscano@fisica.ufjf.br [Departamento de Física, Laboratório de Simulação Computacional, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais 36036-330 (Brazil); Sato, F.; Coura, P.Z.; Dias, R.A. [Departamento de Física, Laboratório de Simulação Computacional, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais 36036-330 (Brazil)
2017-03-15
Numerical simulations have been performed to study the magnetization reversal in Permalloy nano-ellipses, under combined in-plane magnetic fields along the longitudinal and the transverse directions. We have considered nano-ellipses with two different aspect ratios and five thicknesses: 220×80×t nm{sup 3} and 70×50×t nm{sup 3}, where t ranging from 5 to 25 nm in steps of 5 nm. We found that the mechanism of magnetization reversal is not only dependent on the parameters of the magnetic field pulse but also related to the ellipse dimensions. It is known that the reversal time is related to the mechanism behind the magnetization reversal. In particular, ultrafast magnetization reversals occur by coherent rotation, when applying a field oriented mainly perpendicular to the initial magnetization. In order to evaluate the degree of coherence of the magnetization reversal we have introduced a quantity called “coherence index”. Besides complementing the previous studies by including the effect of the thickness on the magnetization reversal, our results indicate that it is possible to obtain magnetization reversals with high degree of coherence in small nano-ellipses by adjusting the geometric factors of the ellipse and the parameters of the magnetic field pulse simultaneously. - Highlights: • Magnetization reversals in single-domain nano-ellipses were investigated. • A parameter to evaluate the degree of coherence of the magnetization reversal was proposed. • A higher coherence index indicates a complete, coherent, rotation of the magnetization.
Solving the rectangular assignment problem and applications
Bijsterbosch, J.; Volgenant, A.
2010-01-01
The rectangular assignment problem is a generalization of the linear assignment problem (LAP): one wants to assign a number of persons to a smaller number of jobs, minimizing the total corresponding costs. Applications are, e.g., in the fields of object recognition and scheduling. Further, we show
Steady turbulent flow in curved rectangular channels
De Vriend, H.J.
1979-01-01
After the study of fully developed and developing steady laminar flow in curved channels of shallow rectangular wet cross-section (see earlier reports in this series), steady turbulent flow in such channels is investigated as a next step towards a mathematical model of the flow in shallow river
A solution for the narrow rectangular punch
Panek, C.F.; Kalker, J.J.
1977-01-01
This paper considers the problem of a rectangular flat ended punch acting on an elastic half-space. An approximate solution is generated through application of the elastic line integral equations. The results produced by this method are then compared with another approximate solution already
International Nuclear Information System (INIS)
Volmer, Marius; Avram, Marioara
2015-01-01
Experimental studies have been carried out on planar Hall effect (PHE) sensors used to detect magnetic nanoparticles employed as labels for biodetection applications. Disk shaped sensors, 1 mm diameter, were structured on Permalloy film, 20 nm thick. To control the sensor magnetisation state and thus the field sensitivity and linearity, a DC biasing field has been applied parallel to the driving current. Maghemite nanoparticles (10 nm) functionalised with Polyethylene glycol (PEG) 6000 were immobilised over the sensor surface using particular magnetisation state and applied magnetic fields. In order to obtain a higher response from the magnetic nanoparticles, it was used a detection setup which allows the application of magnetic fields larger than 100 Oe but avoiding saturation of the PHE signal. Based on this setup, two field scanning methods are presented in this paper. During our experiments, low magnetic moments, of about 1.87×10 −5 emu, have been easily detected. This value corresponds to a mass of 9.35 µg of maghemite nanoparticles functionalised with PEG 6000. The results suggest that this type of structure is feasible for building low cost micrometer sized PHE sensors to be used for high-resolution bio sensing applications. - Highlights: • Disk-shaped Permalloy planar Hall effect sensors have been obtained and tested. • Two field scanning methods have been proposed. • The magnetic nanoparticles can be trapped on the sensor surface. • High detection sensitivity has been obtained
International Nuclear Information System (INIS)
Kopcewicz, M.
1978-01-01
The effect of fast magnetization reversal leading to fast relaxation of the hyperfine field (collapse effect) forced by an external rf magnetic field is studied using the Moessbauer technique for permalloy and invar. The rf collapse and sideband effects are investigated as a function of external rf field, frequency, and intensity. The collapse of the hfs spectrum through unresolved hfs spectrum, triangular shape to a single line, as well as the formation of sidebands is observed. The rf collapse effect is attributed to the rf forced uniform rotation of internal magnetization which causes fast magnetization reversal leading to fast relaxation of the hyperfine field as a result of which the average field at the Moessbauer nuclei is reduced to zero. The difference of the magnetization reversal process in permalloy and invar are discussed. It is shown that the origin of collapse and sideband effects is totaly different: the collapse effect being of purely magnetic origin while the formation of sidebands is due to the rf induced mechanical vibrations of iron atoms within the sample. It is possible to damp sidebands without affecting the collapse effect. The results obtained show that the application of the rf field to ferromagnetic materials gives a unique possibility to force, simulate, and control the relaxation effects in ferromagnetic materials. (author)
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.
Metamaterial Embedded Wearable Rectangular Microstrip Patch Antenna
Directory of Open Access Journals (Sweden)
J. G. Joshi
2012-01-01
Full Text Available This paper presents an indigenous low-cost metamaterial embedded wearable rectangular microstrip patch antenna using polyester substrate for IEEE 802.11a WLAN applications. The proposed antenna resonates at 5.10 GHz with a bandwidth and gain of 97 MHz and 4.92 dBi, respectively. The electrical size of this antenna is 0.254λ×0.5λ. The slots are cut in rectangular patch to reduce the bending effect. This leads to mismatch the impedance at WLAN frequency band; hence, a metamaterial square SRR is embedded inside the slot. A prototype antenna has been fabricated and tested, and the measured results are presented in this paper. The simulated and measured results of the proposed antenna are found to be in good agreement. The bending effect on the performance of this antenna is experimentally verified.
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.
Anisotropic rectangular metric for polygonal surface remeshing
Pellenard, Bertrand; Morvan, Jean-Marie; Alliez, Pierre
2013-01-01
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.
Air-water upward flow in prismatic channel of rectangular base
International Nuclear Information System (INIS)
Carvalho Tofani, P. de.
1984-01-01
Experiments had carried out to investigate the two-phase upward air-water flow structure, in a rectangular test section, by using independent measuring techniques, which comprise direct viewing and photography, electrical probes and gamma-ray attenuation. Flow pattern maps and correlations for flow pattern transitions, void fraction profiles, liquid film thickness and superficial average void fraction are proposed and compared to available data. (Author) [pt
Flow field induced particle accumulation inside droplets in rectangular channels.
Hein, Michael; Moskopp, Michael; Seemann, Ralf
2015-07-07
Particle concentration is a basic operation needed to perform washing steps or to improve subsequent analysis in many (bio)-chemical assays. In this article we present field free, hydrodynamic accumulation of particles and cells in droplets flowing within rectangular micro-channels. Depending on droplet velocity, particles either accumulate at the rear of the droplet or are dispersed over the entire droplet cross-section. We show that the observed particle accumulation behavior can be understood by a coupling of particle sedimentation to the internal flow field of the droplet. The changing accumulation patterns are explained by a qualitative change of the internal flow field. The topological change of the internal flow field, however, is explained by the evolution of the droplet shape with increasing droplet velocity altering the friction with the channel walls. In addition, we demonstrate that accumulated particles can be concentrated, removing excess dispersed phase by splitting the droplet at a simple channel junction.
Fluid Flow and Infrared Image Analyses on Endwall Fitted with Short Rectangular Plate Fin
Institute of Scientific and Technical Information of China (English)
Kenyu OYAKAWA; Islam Md. DIDARUL; Minoru YAGA
2006-01-01
An experimental investigation is carried out to study fluid flow and heat transfer characteristics on the endwall fitted with arrays ( 7 × 7 ) of short rectangular plate fins of different pattern (co-angular and zigzag) for different pitch ratio. Experiments were conducted in a rectangular duct of 50 mm height for an air flow of Reynolds number ranged from 18750 to 62500 based on the equivalent diameter and air velocity of the duct. Infrared image analysis technique was employed to make clear the characteristics of local heat transfer coefficients on fin base, endwall and overall surface. Flow pattern around the short rectangular plates were visualized by inducing fluorescent dye in a water channel and longitudinal vortices were observed. Increasing the distance between plates in flow direction causes heat transfer enhancement for co-angular pattern, while decreasing the distance causes heat transfer enhancement for zigzag pattern. Zigzag pattern with pitch ratio 2 is found to be more effective in heat transfer enhancement than any other cases investigated.
Conformal boundary state for the rectangular geometry
Energy Technology Data Exchange (ETDEWEB)
Bondesan, R., E-mail: roberto.bondesan@cea.fr [Institute de Physique Theorique, CEA Saclay, F-91191 Gif-sur-Yvette (France); LPTENS, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris (France); Institut Henri Poincare, 11 rue Pierre et Marie Curie, 75231 Paris (France); Dubail, J. [Department of Physics, Yale University, P.O. Box 208120, New Haven, CT 06520-8120 (United States); Jacobsen, J.L. [LPTENS, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris (France); Institut Henri Poincare, 11 rue Pierre et Marie Curie, 75231 Paris (France); Universite Pierre et Marie Curie, 4 place Jussieu, 75252 Paris (France); Saleur, H. [Institute de Physique Theorique, CEA Saclay, F-91191 Gif-sur-Yvette (France); Institut Henri Poincare, 11 rue Pierre et Marie Curie, 75231 Paris (France); Physics Department, USC, Los Angeles, CA 90089-0484 (United States)
2012-09-11
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.
Numerical study on rectangular microhollow cathode discharge
International Nuclear Information System (INIS)
He Shoujie; Ouyang Jiting; He Feng; Li Shang
2011-01-01
Rectangular microhollow cathode discharge in argon is investigated by using two-dimensional time-dependent self-consistent fluid model. The electric potential, electric field, particle density, and mean electron energy are calculated. The results show that hollow cathode effect can be onset in the present configuration, with strong electric field and high mean electron energy in the cathode fall while high density and quasineutral plasma in the negative glow. The potential well and electric filed reversal are formed in the negative glow region. It is suggested that the presence of large electron diffusion flux necessitates the field reversal and potential well.
Droplet size in a rectangular Venturi scrubber
Costa, M. A. M.; Henrique, P. R.; Gonçalves, J. A. S.; Coury, J.R.
2004-01-01
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...
Design of open rectangular and trapezoidal channels
González, C. P.; Vera, P. E.; Carrillo, G.; García, S.
2018-04-01
In this work, the results of designing open channels in rectangular and trapezoidal form are presented. For the development of the same important aspects were taken as determination of flows by means of formula of the rational method, area of the surface for its implementation, optimal form of the flow to meet the needs of that environment. In the design the parameter of the hydraulic radius expressed in terms of the hydraulic area and wet perimeter was determined, considering that the surface on which the fluid flows is the product of the perimeter of the section and the length of the channel and where shear is generated by the condition of no slippage.
A CPW-Fed Rectangular Ring Monopole Antenna for WLAN Applications
Directory of Open Access Journals (Sweden)
Sangjin Jo
2014-01-01
Full Text Available 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 that the antenna has a compact size of 21.4×59.4 mm2, an impedance bandwidths of 2.21–2.70 GHz and 5.04–6.03 GHz, and a reflection coefficient of less than −10 dB. The antenna also exhibits an almost omnidirectional radiation pattern. This simple compact antenna with favorable frequency characteristics therefore is attractive for applications in dual-band WLAN.
Simulation of natural convection in a rectangular loop using finite elements
International Nuclear Information System (INIS)
Pepper, D.W.; Hamm, L.L.; Kehoe, A.B.
1984-01-01
A two-dimensional finite-element analysis of natural convection in a rectangular loop is presented. A psi-omega formulation of the Boussinesque approximation to the Navier-Stokes equation is solved by the false transient technique. Streamlines and isotherms at Ra = 10 4 are shown for three different modes of heating. The results indicate that corner effects should be considered when modeling flow patterns in thermosyphons
Regionalization of the Modified Bartlett-Lewis Rectangular Pulse Stochastic Rainfall Model
Dongkyun Kim; Francisco Olivera; Huidae Cho; Scott A. Socolofsky
2013-01-01
Parameters of the Modified Bartlett-Lewis Rectangular Pulse (MBLRP) stochastic rainfall simulation model were regionalized across the contiguous United States. Three thousand four hundred forty-four National Climate Data Center (NCDC) rain gauges were used to obtain spatial and seasonal patterns of the model parameters. The MBLRP model was calibrated to minimize the discrepancy between the precipitation depth statistics between the observed and MBLRP-generated precipitation time series. These...
Rectangular source integral and recurrence relations
International Nuclear Information System (INIS)
Prabha, Hem
2007-01-01
In this paper Hubbell's rectangular source integral H'(a,b), which is a double integral, is expressed as a series of many converging single integrals I n (a,b). Recurrence relations relate these integrals. Once one integral I 1 is computed, recurrence relations are used to compute other integrals. I 1 (a,b) can be computed analytically. H'(a,b) is approximated by considering the first seven terms in the series and the results are found to give good results for various values of a and b. Results are presented for the values of a and b (0.1 to 20 and to 2), respectively. The rate of convergence depends on the values of a and b
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.
Large - scale Rectangular Ruler Automated Verification Device
Chen, Hao; Chang, Luping; Xing, Minjian; Xie, Xie
2018-03-01
This paper introduces a large-scale rectangular ruler automated verification device, which consists of photoelectric autocollimator and self-designed mechanical drive car and data automatic acquisition system. The design of mechanical structure part of the device refer to optical axis design, drive part, fixture device and wheel design. The design of control system of the device refer to hardware design and software design, and the hardware mainly uses singlechip system, and the software design is the process of the photoelectric autocollimator and the automatic data acquisition process. This devices can automated achieve vertical measurement data. The reliability of the device is verified by experimental comparison. The conclusion meets the requirement of the right angle test procedure.
The demagnetizing factors for the rectangular samples
International Nuclear Information System (INIS)
Akishin, P.G.; Gaganov, I.A.
1990-01-01
The influence of the demagnetization effect on the distribution of internal magnetic fields for finite samples is considered. The boundary integral method is used to compute the space distribution of the magnetic field in rectangular samples. On the basis of these calculations we compute the distribution of demagnetization factors in the sample for μSR experimental set-up with the real field geometry. The corresponding mathematical expectation and dispersion of this distribution are estimated. The results of the calculation are used in the analysis of the μSR data obtained for high T c superconductors. It is shown for these compounds that the correction to the penetration depth related to the broadening of the field distribution, is not more than 5%. 8 refs.; 2 figs.; 1 tab
Method and structure for cache aware transposition via rectangular subsections
Gustavson, Fred Gehrung; Gunnels, John A
2014-02-04
A method and structure for transposing a rectangular matrix A in a computer includes subdividing the rectangular matrix A into one or more square submatrices and executing an in-place transposition for each of the square submatrices A.sub.ij.
direct method of analysis of an isotropic rectangular plate direct
African Journals Online (AJOL)
eobe
This work evaluates the static analysis of an isotropic rectangular plate with various the static analysis ... method according to Ritz is used to obtain the total potential energy of the plate by employing the used to ..... for rectangular plates analysis, as the behavior of the ... results obtained by previous research work that used.
Towards characterizing graphs with a sliceable rectangular dual
Kusters, V.; Speckmann, B.; Di Giacomo, E.; Lubiw, A.
2015-01-01
Let G be a plane triangulated graph. A rectangular dual of G is a partition of a rectangle R into a set R of interior-disjoint rectangles, one for each vertex, such that two regions are adjacent if and only if the corresponding vertices are connected by an edge. A rectangular dual is sliceable if it
Obtaining S values for rectangular--solid tumors inside rectangular--solid host organs
International Nuclear Information System (INIS)
Stinchcomb, T.G.; Durham, J.S.; Fisher, D.R.
1991-01-01
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
Directory of Open Access Journals (Sweden)
WANG Minhao
2017-08-01
Full Text Available Plate structures with openings are common in many engineering structures. The study of the vibration characteristics of such structures is directly related to the vibration reduction, noise reduction and stability analysis of an overall structure. This paper conducts research into the free vibration characteristics of a thin elastic plate with a rectangular opening parallel to the plate in an arbitrary position. We use the improved Fourier series to represent the displacement tolerance function of the rectangular plate with an opening. We can divide the plate into an eight zone plate to simplify the calculation. We then use linear springs, which are uniformly distributed along the boundary, to simulate the classical boundary conditions and the boundary conditions of the boundaries between the regions. According to the energy functional and variational method, we can obtain the overall energy functional. We can also obtain the generalized eigenvalue matrix equation by studying the extremum of the unknown improved Fourier series expansion coefficients. We can then obtain the natural frequencies and corresponding vibration modes of the rectangular plate with an opening by solving the equation. We then compare the calculated results with the finite element method to verify the accuracy and effectiveness of the method proposed in this paper. Finally, we research the influence of the boundary condition, opening size and opening position on the vibration characteristics of a plate with an opening. This provides a theoretical reference for practical engineering application.
International Nuclear Information System (INIS)
Yu Zhiting; Tan Sichao; Yuan Hongsheng; Zhuang Nailiang; Chen Hanying
2015-01-01
An experimental study was conducted to investigate the flow instability in a vertical mini-rectangular channel with distilled water as the working fluid. The rotational speed of the primary pump is gradually reduced to lower the inlet flow rate until the flow becomes unstable, while maintaining all other thermal parameters unchanged. Three types of instability, characterized by large amplitude oscillation, small amplitude oscillation and flow excursion, were identified from the experimental data. A stability map for the vertical mini-rectangular channel under forced circulation was established based on the Subcooling number and Phase Change number. The oscillation periods were correlated with the fluid transit time and the boiling delay time. A flow pattern map for vertical upward flow in a mini-rectangular channel was applied to confirm the flow patterns during the oscillation. The mechanisms of the three types of instability were obtained by considering several types of flow instabilities and comparing them with the oscillations observed in this work. (author)
Energy Technology Data Exchange (ETDEWEB)
Ohtake, Mitsuru, E-mail: ohtake@futamoto.elect.chuo-u.ac.jp [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Higuchi, Jumpei; Yabuhara, Osamu [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan); Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan)
2011-09-30
Permalloy (Py) single-crystal films with bcc structure were obtained on GaAs(011){sub B3} single-crystal substrates by ultra high vacuum rf magnetron sputtering. The film growth and the detailed film structures were investigated by refection high energy electron diffraction and pole figure X-ray diffraction. bcc-Py films epitaxially grow on the substrates in the orientation relationship of Py(011)[011-bar]{sub bcc} || GaAs(011)[011-bar]{sub B3}. The lattice constant of bcc-Py film is determined to be a = 0.291 nm. With increasing the film thickness, parts of the bcc crystal transform into more stable fcc structure by atomic displacement parallel to the bcc{l_brace}011{r_brace} close-packed planes. The resulting film thus consists of a mixture of bcc and fcc crystals. The phase transformation mechanism is discussed based on the experimental results. The in-plane magnetization properties reflecting the magnetocrystalline anisotropy of bcc-Py crystal are observed for the Py films grown on GaAs(011){sub B3} substrates.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Zhangming; Xu, Wei; Guo, Ting; Jiang, Yinzhu; Yan, Mi, E-mail: mse_yanmi@zju.edu.cn
2014-05-01
Highlights: • Effect of processing parameters on the properties of MP powder cores was studied. • Effective magnetic permeability was enhanced from 45 to 160 after annealing. • A core loss of 780 mw/cm{sup 3} (100 kHz, 100 mT) was obtained. - Abstract: Effects of compaction and annealing process on the magnetic properties and microstructures of molybdenum permalloy (MP) powder cores have been investigated. MP compacts, with density as high as 92% of the theoretical value, were obtained under 1800 MPa compaction pressure. The MP powder cores show an enhanced effective magnetic permeability of 160 after post-annealing at 690 °C, which is attributed to the relief of internal stress rather than the phase transformation evidenced by the XRD analysis. However, higher annealing temperature destroys the insulating layer, resulting in the drop of the electrical resistivity, the effective magnetic permeability as well as the frequency stability. The results show that the samples compacted at 1800 MPa and annealed at 690 °C exhibit excellent magnetic properties, with core loss of 780 mw/cm{sup 3} (100 kHz, 100 mT) and effective magnetic permeability of 160 whose frequency stability is up to 1 MHz.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Dong, E-mail: physzd@yahoo.com [School of Physics Science and Information Engineering, Key Lab. of Communication Science and Technology of Shandong Province, Liaocheng University, Liaocheng 252059 (China); Physics Department, Southeast University, Nanjing 211189 (China); Yue, Jinjin; Jiang, Sheng [Physics Department, Southeast University, Nanjing 211189 (China); Zhai, Ya, E-mail: yazhai@seu.edu.cn [Physics Department, Southeast University, Nanjing 211189 (China); National Laboratory of Solid Microstructures, Nanjing University, Nanjing 210093 (China); Du, Jun; Zhai, Hongru [National Laboratory of Solid Microstructures, Nanjing University, Nanjing 210093 (China)
2016-07-05
The mechanism of angular dependence of ferromagnetic resonance linewidth of dilute Tb and Nd doping in permalloy thin films with various thicknesses of adjacent copper layer are investigated by experimental approach and theoretical fitting by considering the contributions from intrinsic spin-orbit coupling, inhomogeneous broadening and two-magnon scattering. The results show that the damping coefficient α, by intrinsic contribution extracted from ferromagnetic resonance linewidth, increases from 0.0153 to 0.0218 for NiFe–Nd films and from 0.0193 to 0.0261 for NiFe–Tb films resulting from the spin pumping effect at the interface of NiFe–Nd(or Tb)/Cu as the thickness of copper layer increases from 1 nm to 15 nm. The surface magnetic anisotropy constant K{sub 1} is obtained and shows an decreasing trend from positive to negative, which implies that the copper layer could reduce the surface perpendicular anisotropy. The fitting spin mixed conductivity is (2.72 ± 0.18) × 10{sup 15} cm{sup −2} at NiFe–Tb/Cu interface and (2.4 ± 0.2) × 10{sup 15} cm{sup −2} at Cu/NiFe–Nd interface, respectively. - Highlights: • The thickness of Cu buffer layer affects the surface perpendicular anisotropy of FM layer. • The interface roughness could be investigated by using FMR linewidth. • The damping coefficient is enhanced by spin-pumping effect.
International Nuclear Information System (INIS)
Ohtake, Mitsuru; Higuchi, Jumpei; Yabuhara, Osamu; Kirino, Fumiyoshi; Futamoto, Masaaki
2011-01-01
Permalloy (Py) single-crystal films with bcc structure were obtained on GaAs(011) B3 single-crystal substrates by ultra high vacuum rf magnetron sputtering. The film growth and the detailed film structures were investigated by refection high energy electron diffraction and pole figure X-ray diffraction. bcc-Py films epitaxially grow on the substrates in the orientation relationship of Py(011)[011-bar] bcc || GaAs(011)[011-bar] B3 . The lattice constant of bcc-Py film is determined to be a = 0.291 nm. With increasing the film thickness, parts of the bcc crystal transform into more stable fcc structure by atomic displacement parallel to the bcc{011} close-packed planes. The resulting film thus consists of a mixture of bcc and fcc crystals. The phase transformation mechanism is discussed based on the experimental results. The in-plane magnetization properties reflecting the magnetocrystalline anisotropy of bcc-Py crystal are observed for the Py films grown on GaAs(011) B3 substrates.
Rectangular illumination using a secondary optics with cylindrical lens for LED street light.
Chen, Hsi-Chao; Lin, Jun-Yu; Chiu, Hsuan-Yi
2013-02-11
The illumination pattern of an LED street light is required to have a rectangular distribution at a divergence-angle ratio of 7:3 for economical illumination. Hence, research supplying a secondary optics with two cylindrical lenses was different from free-form curvature for rectangular illumination. The analytical solution for curvatures with different ratio rectangles solved this detail by light tracing and boundary conditions. Similarities between the experiments and the simulation for a single LED and a 9-LED module were analyzed by Normalized Cross Correlation (NCC), and the error rate was studied by the Root Mean Square (RMS). The tolerance of position must be kept under ± 0.2 mm in the x, y and z directions to ensure that the relative illumination is over 99%.
Energy Technology Data Exchange (ETDEWEB)
Kim, T. H.; Yun, B. J.; Jeong, J. H. [Pusan National University, Geunjeong-gu, Busan (Korea, Republic of)
2015-05-15
Studies were mostly about flow in upward flow in medium size circular tube. Although there are great differences between upward and downward flow, studies on vertical upward flow are much more active than those on vertical downward flow in a channel. In addition, due to the increase of surface forces and friction pressure drop, the pattern of gas-liquid two-phase flow bounded to the gap of inside the rectangular channel is different from that in a tube. The downward flow in a rectangular channel is universally applicable to cool the plate type nuclear fuel in research reactor. The sub-channel of the plate type nuclear fuel is designed with a few millimeters. Downward air-water two-phase flow in vertical rectangular channel was experimentally observed. The depth, width, and length of the rectangular channel is 2.35 mm, 66.7 mm, and 780 mm, respectively. The test section consists of transparent acrylic plates confined within a stainless steel frame. The flow patterns of the downward flow in high liquid velocity appeared to be similar to those observed in previous studies with upward flow. In downward flow, the transition lines for bubbly-slug and slug-churn flow shift to left in the flow regime map constructed with abscissa of the superficial gas velocity and ordinate of the superficial liquid velocity. The flow patterns observed with downward flow at low liquid velocity are different from those with upward flow.
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.
Physics from angular projection of rectangular grids
International Nuclear Information System (INIS)
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 scholarly value and applications for data extraction techniques to study the physics of various systems. Our work may help 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 applications in various branches of physical sciences, including crystallography, astrophysics, and bulk properties of materials. (paper)
Rectangular maximum-volume submatrices and their applications
Mikhalev, Aleksandr; Oseledets, I.V.
2017-01-01
We introduce a definition of the volume of a general rectangular matrix, which is equivalent to an absolute value of the determinant for square matrices. We generalize results of square maximum-volume submatrices to the rectangular case, show a connection of the rectangular volume with an optimal experimental design and provide estimates for a growth of coefficients and an approximation error in spectral and Chebyshev norms. Three promising applications of such submatrices are presented: recommender systems, finding maximal elements in low-rank matrices and preconditioning of overdetermined linear systems. The code is available online.
Rectangular maximum-volume submatrices and their applications
Mikhalev, Aleksandr
2017-10-18
We introduce a definition of the volume of a general rectangular matrix, which is equivalent to an absolute value of the determinant for square matrices. We generalize results of square maximum-volume submatrices to the rectangular case, show a connection of the rectangular volume with an optimal experimental design and provide estimates for a growth of coefficients and an approximation error in spectral and Chebyshev norms. Three promising applications of such submatrices are presented: recommender systems, finding maximal elements in low-rank matrices and preconditioning of overdetermined linear systems. The code is available online.
Rectangular-cladding silicon slot waveguide with improved nonlinear performance
Huang, Zengzhi; Huang, Qingzhong; Wang, Yi; Xia, Jinsong
2018-04-01
Silicon slot waveguides have great potential in hybrid silicon integration to realize nonlinear optical applications. We propose a rectangular-cladding hybrid silicon slot waveguide. Simulation result shows that, with a rectangular-cladding, the slot waveguide can be formed by narrower silicon strips, so the two-photon absorption (TPA) loss in silicon is decreased. When the cladding material is a nonlinear polymer, the calculated TPA figure of merit (FOMTPA) is 4.4, close to the value of bulk nonlinear polymer of 5.0. This value confirms the good nonlinear performance of rectangular-cladding silicon slot waveguides.
Diversity of acoustic streaming in a rectangular acoustofluidic field.
Tang, Qiang; Hu, Junhui
2015-04-01
Diversity of acoustic streaming field in a 2D rectangular chamber with a traveling wave and using water as the acoustic medium is numerically investigated by the finite element method. It is found that the working frequency, the vibration excitation source length, and the distance and phase difference between two separated symmetric vibration excitation sources can cause the diversity in the acoustic streaming pattern. It is also found that a small object in the acoustic field results in an additional eddy, and affects the eddy size in the acoustic streaming field. In addition, the computation results show that with an increase of the acoustic medium's temperature, the speed of the main acoustic streaming decreases first and then increases, and the angular velocity of the corner eddies increases monotonously, which can be clearly explained by the change of the acoustic dissipation factor and shearing viscosity of the acoustic medium with temperature. Commercialized FEM software COMSOL Multiphysics is used to implement the computation tasks, which makes our method very easy to use. And the computation method is partially verified by an established analytical solution. Copyright © 2014 Elsevier B.V. All rights reserved.
Helium-air counter flow in rectangular channels
International Nuclear Information System (INIS)
Fumizawa, Motoo; Tanaka, Gaku; Zhao, Hong; Hishida, Makoto; Shiina, Yasuaki
2004-01-01
This paper deals with numerical analysis of helium-air counter flow in a rectangular channel with an aspect ratio of 10. The channel has a cross sectional area of 5-50 mm and a length of 200 mm. The inclination angle was varied from 0 to 90 degree. The velocity profiles and concentration profiles were analyzed with a computer program [FLUENT]. Following main features of the counter flow are discussed based on the calculated results. (1) Time required for establishing a quasi-steady state counter flow. (2) The relationship between the inclination angle and the flow patterns of the counter flow. (3) The developing process of velocity profiles and concentration profiles. (4) The relationship between the inclination angle of the channel and the velocity profiles of upward flow and the downward flow. (5) The relationship between the concentration profile and the inclination angle. (6) The relationship between the net in-flow rate and the inclination angle. We compared the computed velocity profile and the net in-flow rate with experimental data. A good agreement was obtained between the calculation results and the experimental results. (author)
Directory of Open Access Journals (Sweden)
Xiao Wen
2016-05-01
Full Text Available Magnetically soft NiZn ferrite (Ni0.5Zn0.5Fe2O4 nanoparticles are embedded within a permalloy (Ni-Fe matrix via an electro-infiltration process as thin films intended for use as on-chip inductor cores in the MHz frequency regime. A layer of NiZn ferrite nanoparticles is first deposited, and then permalloy is electroplated through the voids to encapsulate the particles and form three-dimensional ferrite/alloy nanocomposites. The composites are estimated to contain 37% ferrite by volume and exhibit a relative permeability of ∼320, a saturation of ∼1.15 T, and an operational bandwidth of 93 MHz. Compared to a permalloy thin film of similar thickness, the nanocomposite exhibits 39% higher electrical resistivity and 50% higher bandwidth.
analytical bending solution of all clamped isotropic rectangular plate
African Journals Online (AJOL)
HP
PLATE ON WINKLER'S FOUNDATION USING CHARACTERISTIC. ORTHOGONAL ... foundations, storage tanks, swimming pools, floor system of buildings, highways ..... “Energy Methods in Theory of Rectangular Plates. (use of Polynomial ...
Rectangular waveform linear transformer driver module design
International Nuclear Information System (INIS)
Zhao Yue; Xie Weiping; Zhou Liangji; Chen Lin
2014-01-01
Linear Transformer Driver is a novel pulsed power technology, its main merits include a parallel LC discharge array and Inductive Voltage Adder. The parallel LC discharge array lowers the whole circuit equivalent inductance and the Inductive Voltage Adder unites the modules in series in order to create a high electric field grads, meanwhile, restricts the high voltage in a small space. The lower inductance in favor of LTD output a fast waveform and IVA confine high voltage in secondary cavity. In recently, some LTD-based pulsed power system has been development yet. The usual LTD architecture provides damped sine shaped output pulses that may not be suitable in flash radiography, high power microwave production, z-pinch drivers, and certain other applications. A more suitable driver output pulse would have a flat or inclined top (slightly rising or falling). In this paper, we present the design of an LTD cavity that generates this type of the output pulse by including within its circular array some number of the harmonic bricks in addition to the standard bricks according to Fourier progression theory. The parallel LC discharge array circuit formula is introduced by Kirchhoff Law, and the sum of harmonic is proofed as an analytic result, meanwhile, rationality of design is proved by simulation. Varying gas spark discharge dynamic resistance with harmonic order and switches jitter are analyzed. The results are as following: The more harmonic order is an approach to the ideal rectangular waveform, but lead to more system complexity. The capacity decreases as harmonic order increase, and gas spark discharge dynamic resistance rises with the capacity. The rising time protracts and flat is decay or even vanishes and the shot to shot reproducibility is degenerate as the switches jitter is high. (authors)
Directory of Open Access Journals (Sweden)
Waheed Khan
2018-03-01
Full Text Available We report the first results of functional properties of nitrogenized silver-permalloy thin films deposited on polyethylene terephthalic ester {PETE (C10H8O4n} flexible substrates by magnetron sputtering. These new soft magnetic thin films have magnetization that is comparable to pure Ni81Fe19 permalloy films. Two target compositions (Ni76Fe19Ag5 and Ni72Fe18Ag10 were used to study the effect of compositional variation and sputtering parameters, including nitrogen flow rate on the phase evolution and surface properties. Aggregate flow rate and total pressure of Ar+N2 mixture was 60 sccm and 0.55 Pa, respectively. The distance between target and the substrate was kept at 100 mm, while using sputtering power from 100–130 W. Average film deposition rate was confirmed at around 2.05 nm/min for argon atmosphere and was reduced to 1.8 nm/min in reactive nitrogen atmosphere. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, vibrating sample magnetometer, and contact angle measurements were used to characterize the functional properties. Nano sized character of films was confirmed by XRD and SEM. It is found that the grain size was reduced by the formation of nitride phase, which in turns enhanced the magnetization and lowers the coercivity. Magnetic field coupling efficiency limit was determined from 1.6–2 GHz frequency limit. The results of comparable magnetic performance, lowest magnetic loss, and highest surface free energy, confirming that 15 sccm nitrogen flow rate at 115 W is optimal for producing Ag-doped permalloy flexible thin films having excellent magnetic field coupling efficiency.
Tau method approximation of the Hubbell rectangular source integral
International Nuclear Information System (INIS)
Kalla, S.L.; Khajah, H.G.
2000-01-01
The Tau method is applied to obtain expansions, in terms of Chebyshev polynomials, which approximate the Hubbell rectangular source integral:I(a,b)=∫ b 0 (1/(√(1+x 2 )) arctan(a/(√(1+x 2 )))) This integral corresponds to the response of an omni-directional radiation detector situated over a corner of a plane isotropic rectangular source. A discussion of the error in the Tau method approximation follows
Critical heat flux correlation for thin rectangular channels
International Nuclear Information System (INIS)
Tanaka, Futoshi; Mishima, Kaichiro; Hibiki, Takashi
2007-01-01
The effect of heated length on Critical heat flux (CHF) in thin rectangular channels was studied based on CHF data obtained under atmospheric pressure. CHF in small channels has been widely studied in the past decades but most of the studies are related to CHF in round tubes. Although basic mechanisms of burnout in thin rectangular channels are similar to tubes, applicability of CHF correlations for tubes to rectangular channels are questionable since CHF in rectangular channels are affected by the existence of non-heated walls and the non-circular geometry of channel circumference. Several studies of CHF in thin rectangular channels have been reported in relation to thermal hydraulic design of research reactors and neutron source targets and CHF correlations have been proposed, but the studies mostly focus on CHFs under geometrical conditions of the application of interest. In his study, existing CHF data obtained in thin rectangular channels were collected and the effect of heated length on CHF was examined. Existing CHF correlations were verified with positive quality flow CHF data but none of the correlations successfully reproduced the CHF for a wide range of heated length. A new CHF correlation for qualify region applicable to a wide range of heated length was developed based on the collected data. (author)
FLOW VISUALIZATION OF RECTANGULAR SLOT AIR JET IMPINGEMENT ON FLAT SURFACES
Satheesha V *1, B. K. Muralidhra2, Abhilash N3, C. K. Umesh4
2018-01-01
Jet impingement near the mid-chord of the gas turbine blade is treated as a flat plate. Experimental and numerical investigations are carried out for a single slot air jet impinging on flat surface for two different rectangular slots of dimension (3mm x 65 mm) and (5mm x 65 mm). Experimentation is done to study the flow pattern topography on the flat target plate, with varying the flow rate from 20 LPM to 50 LPM by varying the nozzle to plate distance from 9 mm to 24 mm for slot jet of 3mm an...
Joining of Aluminium Alloy Sheets by Rectangular Mechanical Clinching
International Nuclear Information System (INIS)
Abe, Y.; Mori, K.; Kato, T.
2011-01-01
A mechanical clinching has the advantage of low running costs. However, the joint strength is not high. To improve the maximum load of the joined sheets by a mechanical clinching, square and rectangular mechanical clinching were introduced. In the mechanical clinching, the two sheets are mechanically joined by forming an interlock between the lower and upper sheets by the punch and die. The joined length with the interlock was increased by the rectangular punch and die. The deforming behaviours of the sheets in the mechanical clinching were investigated, and then the interlock in the sheets had distribution in the circumference of the projection. Although the interlocks were formed in both projection side and diagonal, the interlock in the diagonal was smaller because of the long contact length between the lower sheet and the die cavity surface. The maximum load of the joined sheets by the rectangular mechanical clinching was two times larger than the load by the round mechanical clinching.
A two-component NZRI metamaterial based rectangular cloak
Directory of Open Access Journals (Sweden)
Sikder Sunbeam Islam
2015-10-01
Full Text Available A new two-component, near zero refractive index (NZRI metamaterial is presented for electromagnetic rectangular cloaking operation in the microwave range. In the basic design a pi-shaped, metamaterial was developed and its characteristics were investigated for the two major axes (x and z-axis wave propagation through the material. For the z-axis wave propagation, it shows more than 2 GHz bandwidth and for the x-axis wave propagation; it exhibits more than 1 GHz bandwidth of NZRI property. The metamaterial was then utilized in designing a rectangular cloak where a metal cylinder was cloaked perfectly in the C-band area of microwave regime. The experimental result was provided for the metamaterial and the cloak and these results were compared with the simulated results. This is a novel and promising design for its two-component NZRI characteristics and rectangular cloaking operation in the electromagnetic paradigm.
Errors generated with the use of rectangular collimation
International Nuclear Information System (INIS)
Parks, E.T.
1991-01-01
This study was designed to determine whether various techniques for achieving rectangular collimation generate different numbers and types of errors and remakes and to determine whether operator skill level influences errors and remakes. Eighteen students exposed full-mouth series of radiographs on manikins with the use of six techniques. The students were grouped according to skill level. The radiographs were evaluated for errors and remakes resulting from errors in the following categories: cone cutting, vertical angulation, and film placement. Significant differences were found among the techniques in cone cutting errors and remakes, vertical angulation errors and remakes, and total errors and remakes. Operator skill did not appear to influence the number or types of errors or remakes generated. Rectangular collimation techniques produced more errors than did the round collimation techniques. However, only one rectangular collimation technique generated significantly more remakes than the other techniques
Spin pumping and inverse spin Hall effects in heavy metal/antiferromagnet/Permalloy trilayers
Saglam, Hilal; Zhang, Wei; Jungfleisch, M. Benjamin; Jiang, Wanjun; Pearson, John E.; Hoffmann, Axel
Recent work shows efficient spin transfer via spin waves in insulating antiferromagnets (AFMs), suggesting that AFMs can play a more active role in the manipulation of ferromagnets. We use spin pumping and inverse spin Hall effect experiments on heavy metal (Pt and W)/AFMs/Py (Ni80Fe20) trilayer structures, to examine the possible spin transfer phenomenon in metallic AFMs, i . e . , FeMn and PdMn. Previous work has studied electronic effects of the spin transport in these materials, yielding short spin diffusion length on the order of 1 nm. However, the work did not examine whether besides diffusive spin transport by the conduction electrons, there are additional spin transport contributions from spin wave excitations. We clearly observe spin transport from the Py spin reservoir to the heavy metal layer through the sandwiched AFMs with thicknesses well above the previously measured spin diffusion lengths, indicating that spin transport by spin waves may lead to non-negligible contributions This work was supported by US DOE, OS, Materials Sciences and Engineering Division. Lithographic patterning was carried out at the CNM, which is supported by DOE, OS under Contract No. DE-AC02-06CH11357.
Energy Technology Data Exchange (ETDEWEB)
Vilanova Vidal, Enrique
2012-09-19
(SSE) has been discovered. This effect is within the framework of spin caloritronics and it generates a ''spin voltage'' due to a temperature gradient in magnetic materials. Here, the preliminary measurements of the spin-Seebeck effect in permalloy and Heusler compounds are presented.
International Nuclear Information System (INIS)
Zhang Chunwei; Qiu Suizheng; Yan Mingyu; Wang Bulei; Nie Changhua
2005-01-01
The flow regime transition criteria for the boiling water two-phase flow in horizontal rectangular narrow channels (1 x 20 mm, 2 x 20 mm) were theoretically explored. The discernible flow patterns were bubble, intermittent slug, churn, annular and steam-water separation flow. By using two-fluid model, equations of conservation of momentum were established for the two-phase flow. New flow-regime criteria were obtained and agreed well with the experiment data. (authors)
Natural Vibration Analysis of Clamped Rectangular Orthotropic Plates
dalaei, m.; kerr, a. d.
The natural vibrations of clamped rectangular orthotropic plates are analyzed using the extended Kantorovich method. The developed iterative scheme converges very rapidly to the final result. The obtained natural frequencies are evaluated for a square plate made of Kevlar 49 Epoxy and the obtained results are compared with those published by Kanazawa and Kawai, and by Leissa. The agreement was found to be very close. As there are no exact analytical solutions for clamped rectangular plates, the generated closed form expression for the natural modes, and the corresponding natural frequencies, are very suitable for use in engineering analyses.
Perron-Frobenius Theorem for Rectangular Tensors and Directed Hypergraphs
Lu, Linyuan; Yang, Arthur L. B.; Zhao, James J. Y.
2018-01-01
For any positive integers $r$, $s$, $m$, $n$, an $(r,s)$-order $(n,m)$-dimensional rectangular tensor ${\\cal A}=(a_{i_1\\cdots i_r}^{j_1\\cdots j_s}) \\in ({\\mathbb R}^n)^r\\times ({\\mathbb R}^m)^s$ is called partially symmetric if it is invariant under any permutation on the lower $r$ indexes and any permutation on the upper $s$ indexes. Such partially symmetric rectangular tensor arises naturally in studying directed hypergraphs. Ling and Qi [Front. Math. China, 2013] first studied the $(p,q)$-...
A new metamaterial-based wideband rectangular invisibility cloak
Islam, S. S.; Hasan, M. M.; Faruque, M. R. I.
2018-02-01
A new metamaterial-based wideband electromagnetic rectangular cloak is being introduced in this study. The metamaterial unit cell shows sharp transmittances in the C- and X-bands and displays wideband negative effective permittivity region there. The metamaterial unit cell was then applied in designing a rectangular-shaped electromagnetic cloak. The scattering reduction technique was adopted for the cloaking operation. The cloak operates in the certain portion of C-and X-bands that covers more than 4 GHz bandwidth region. The experimental results were provided as well for the metamaterial and the cloak.
Development of micro pattern cutting simulation software
International Nuclear Information System (INIS)
Lee, Jong Min; Song, Seok Gyun; Choi, Jeong Ju; Novandy, Bondhan; Kim, Su Jin; Lee, Dong Yoon; Nam, Sung Ho; Je, Tae Jin
2008-01-01
The micro pattern machining on the surface of wide mold is not easy to be simulated by conventional software. In this paper, a software is developed for micro pattern cutting simulation. The 3d geometry of v-groove, rectangular groove, pyramid and pillar patterns are visualized by c++ and OpenGL library. The micro cutting force is also simulated for each pattern
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 Rectangular Microstrip Antennas with Air Substrates ...
African Journals Online (AJOL)
This paper presents an analysis of rectangular microstrip antennas with air substrates. The effect of the substrate thickness on the bandwidth and the efficiency are examined. An additional thin layer supporting the dielectric material is added to the air substrate in order to make the antenna mechanically rigid and easy to ...
Graphene-based tunable terahertz filter with rectangular ring ...
Indian Academy of Sciences (India)
A plasmonic band-pass filter based on graphene rectangular ring resonator with double narrow gaps is proposed and numerically investigated by finite-difference time-domain (FDTD) simulations. For the filter with or without gaps, the resonant frequencies can be effectively adjusted by changing the width of the graphene ...
Plasma-ﬁlled rippled wall rectangular backward wave oscillator
Indian Academy of Sciences (India)
Performance of the backward wave oscillator (BWO) is greatly enhanced with the introduction of plasma. Linear theory of the dispersion relation and the growth rate have been derived and analysed numerically for plasma-ﬁlled rippled wall rectangular waveguide driven by sheet electron beam. To see the effect of plasma ...
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
The problem of isotropic rectangular plate with four clamped edges
Indian Academy of Sciences (India)
of rectangular plates has been a subject of study in solid mechanics for more than a cen- .... loading is solved first, giving the deflection function for the strip case and .... The authors gratefully acknowledge the advice and encouragement of ...
FDTD Analysis of U-Slot Rectangular Patch Antenna
Luk, K. M.; Tong, K. F.; Shum, S. M.; Lee, K. F.; Lee, R. Q.
1997-01-01
The U-slot rectangular patch antenna (Figure I) has been found experimentally to provide impedance and gain bandwidths of about 300 without the need of stacked or coplanar parasitic elements [1,2]. In this paper, simulation results of the U-slot patch using FDTD analysis are presented. Comparison with measured results are given.
Graphene-based tunable terahertz filter with rectangular ring ...
Indian Academy of Sciences (India)
WEI SU
2017-08-16
Aug 16, 2017 ... Abstract. A plasmonic band-pass filter based on graphene rectangular ring resonator with double narrow gaps is proposed and numerically investigated by finite-difference time-domain (FDTD) simulations. For the filter with or without gaps, the resonant frequencies can be effectively adjusted by changing ...
Optical vortex propagation in few-mode rectangular polymer waveguides
DEFF Research Database (Denmark)
Lyubopytov, Vladimir S.; Chipouline, Arkadi; Zywietz, Urs
2017-01-01
We demonstrate that rectangular few-mode dielectric waveguides, fabricated with standard lithographic technique, can support on-chip propagation of optical vortices. We show that specific superpositions of waveguide eigenmodes form quasi-degenerate modes carrying light with high purity states...
Shielding calculations for changing from circular to a Rectangular ...
African Journals Online (AJOL)
The Radiation Technology Centre (RTC) of the Ghana Atomic Energy Commission operates a 1.85 PBq Co-60 gamma irradiator for research, food preservation and medical sterilization. It has become necessary to improve the do-se rate delivered by changing the circular arrangement of sources to a rectangular one.
Two-phase upward air water flow in a prismatic channel with rectangular base
International Nuclear Information System (INIS)
Carvalho Tofani, P. de
1984-01-01
Two-phase liquid-gas mixtures provide suitable means to simulate water-water vapor flows, which may occur in nuclear reactor cores. The mastery of physical transport phenomena is of great importance, as far as the analysis of such thermal systems is concerned. Within the framework of thermal-hydraulic programs, experiments have been carried out to investigate the two-phase upward air-water flow structure, in a rectangular test section, by using independent measuring techniques, which comprise direct viewing and photography, electrical probes and gamma-ray attenuation. In this paper, flow pattern maps and correlations for flow pattern transitions, void fraction profiles, liquid film thickness and superficial average void fraction are proposed and compared to available data. (Author) [pt
Khan, Md Imran; Billah, Md. Mamun; Rahman, Mohammed Mizanur; Hasan, Mohammad Nasim
2017-12-01
Numerical simulation of steady two-dimensional heat transfer in a rectangular channel with a centered variable speed cylinder has been performed in this paper. In this setup, an isoflux heater is placed at the bottom wall of the channel while the upper wall is kept isothermal with a low temperature. The cylinder's peripheral speed to maximum inlet fluid velocity ratio (ξ) is varied from 0.5 to 1.5 for both clockwise and anticlockwise rotational cases. Air has been considered as working fluid while other system parameters such as Grashof and Reynolds numbers are varied. The effects of rotational speed, Grashof and Reynolds numbers on the streamline pattern, isothermal lines, local and average Nusselt number are analyzed and presented. It is observed the cylinder's rotational direction and speed has a significant effect on the flow pattern, temperature distribution as well as heat transfer characteristics.
International Nuclear Information System (INIS)
Ross, N.; Kostylev, M.; Stamps, R. L.
2014-01-01
Standing spin wave mode frequencies and linewidths in partially disordered perpendicular magnetized arrays of sub-micron Permalloy discs are measured using broadband ferromagnetic resonance and compared to analytical results from a single, isolated disc. The measured mode structure qualitatively reproduces the structure expected from the theory. Fitted demagnetizing parameters decrease with increasing array disorder. The frequency difference between the first and second radial modes is found to be higher in the measured array systems than predicted by theory for an isolated disc. The relative frequencies between successive spin wave modes are unaffected by reduction of the long-range ordering of discs in the array. An increase in standing spin wave resonance linewidth at low applied magnetic fields is observed and grows more severe with increased array disorder.
Egorov, S. V.; Uspenskaya, L. S.
2016-02-01
The kinetics of magnetization reversal in bilayer permalloy-niobium microstrips under the effect of both a pulsed magnetic field and an electric current has been experimentally studied. These two cases turn out to be fundamentally different in the types of arising magnetic structures and in the dynamic characteristics of the processes. Such difference is especially striking at low temperatures. An anomalously high rate of the processes under study is observed. According to the suggested qualitative explanation, this effect is due to nonlinear excitations appearing in front of the moving domain wall if the applied electric current lowers the barriers for its motion. For achieving the final conclusions, more accurate quantitative analysis is needed.
Czech Academy of Sciences Publication Activity Database
Ripka, P.; Platil, A.; Kaspar, P.; Tipek, A.; Malatek, M.; Kraus, Luděk
254-255, - (2003), s. 633-635 ISSN 0304-8853. [Soft Magnetic Material Conference ( SMM 15). Bilbao, 05.09.2001-07.09.2001] R&D Projects: GA MŠk ME 355 Grant - others:HPMF-CT-2000(XE) 00695 Institutional research plan: CEZ:AV0Z1010914 Keywords : magnetic sensors * GMI effect * magnetometer Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.910, year: 2003
Energy Technology Data Exchange (ETDEWEB)
Li, Zi-chao; Qi, Shi; Zhou, Tao; Li, Bing; Shahzad, Muhammad Ali [North China Electric Power Univ., Beijing (China). School of Nuclear Science and Engineering; Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy, Beijing (China); Huang, Yan-ping [Nuclear Reactor Thermal Hydraulics Technology, Chengdu (China). CNNC Key Lab.
2017-12-15
Saturated boiling of two-phase natural circulation has been experimentally investigated based on a natural circulation device with narrow rectangular channels. When heating power reaches a certain range, it is possible to observe the phenomenon of saturated boiling and flow pattern transition in the system. The results show the heat transfer coefficient of saturated boiling decreases with the increasing of pressure, heating power and size of narrow rectangle channels. The buoyancy force causing mixed convection decreases the heat transfer coefficient. Finally, a dimensionless number is introduced, which reflects length to width ratio of rectangular narrow section and Rayleigh number, in order to revise the presented correlation. All errors fall within the range of ±15%.
Measurements of time-dependent liquid-metal magnetohydrodynamic flows in a flat rectangular duct
International Nuclear Information System (INIS)
Buehler, L.; Horanyi, S.
2009-01-01
In the helium-cooled lead lithium (HCLL) blanket, which has been chosen as a reference concept for a liquid-metal breeding blanket to be tested in ITER, the heat is removed by helium cooled plates aligned with the strong toroidal magnetic field that confines the fusion plasma. The liquid breeder lead lithium circulates through gaps of rectangular cross-section between the cooling plates to transport the generated tritium towards external extraction facilities. Under the action of the strong magnetic field, liquid metal flows in conducting rectangular ducts exhibit jet-like velocity profiles in the thin boundary layers near the side walls, which are parallel to the magnetic field like the cooling plates in HCLL blankets. The velocity in these side layers may exceed several times the mean velocity in the duct and it is known that these layers become unstable for sufficiently high Reynolds numbers. The present paper summarizes experimental results for such unstable time-dependent flows in strong magnetic fields, which have been obtained in the MEKKA liquid metal laboratory of the Forschungszentrum Karlsruhe. In particular, spatial and temporal scales of perturbation patterns are identified. The results suggest that the flow between cooling plates in a HCLL blanket is laminar and stable. The observed time-dependent flow behavior appears at larger velocities so that the present results are more relevant for applications in dual coolant concepts where high-velocity jets have been predicted along side walls.
Counter-current gas-liquid two-phase flow in a narrow rectangular channel
International Nuclear Information System (INIS)
Sohn, Byung Hu; Kim, Byong Joo
2000-01-01
A study of counter-current two-phase flow in a narrow rectangular channel has been performed. Two-phase flow patterns and void fractions were experimentally studied in a 760 mm long and 100 mm wide test section with 3.0 mm gap. The resulting data have been compared to previous transition criteria and empirical correlations. The comparison of experimental data to the transition criteria developed by Taitel and Barnea showed good agreement for the bubbly-to-slug transition. For the criteria of Mishima and Ishii to be applicable to the slug to churn transition, a new model seems to be needed for the accurate prediction of the distribution parameter for the counter-current flow in narrow rectangular channels. For the churn-to-annular transition the model of Taitel and Barnea was found to be close to the experimental data. However the model should be improved in conjunction with the channel geometry to accurately predict the counter-current flow limitation and flow transition. It was verified the distribution parameter was well-correlated by the drift-flux model. The distribution parameter for the present study was found to be about 1.2 for all flow regimes except 1.0 for an annular flow. (author)
Computational Investigations in Rectangular Convergent and Divergent Ribbed Channels
Sivakumar, Karthikeyan; Kulasekharan, N.; Natarajan, E.
2018-05-01
Computational investigations on the rib turbulated flow inside a convergent and divergent rectangular channel with square ribs of different rib heights and different Reynolds numbers (Re=20,000, 40,000 and 60,000). The ribs were arranged in a staggered fashion between the upper and lower surfaces of the test section. Computational investigations are carried out using computational fluid dynamic software ANSYS Fluent 14.0. Suitable solver settings like turbulence models were identified from the literature and the boundary conditions for the simulations on a solution of independent grid. Computations were carried out for both convergent and divergent channels with 0 (smooth duct), 1.5, 3, 6, 9 and 12 mm rib heights, to identify the ribbed channel with optimal performance, assessed using a thermo hydraulic performance parameter. The convergent and divergent rectangular channels show higher Nu values than the standard correlation values.
Flow Through a Rectangular-to-Semiannular Diffusing Transition Duct
Foster, Jeff; Wendt, Bruce J.; Reichert, Bruce A.; Okiishi, Theodore H.
1997-01-01
Rectangular-to-semiannular diffusing transition ducts are critical inlet components on supersonic airplanes having bifucated engine inlets. This paper documents measured details of the flow through a rectangular-to-semiannular transition duct having an expansion area ratio of 1.53. Three-dimensional velocity vectors and total pressures at the exit plane of the diffuser are presented. Surface oil-flow visualization and surface static pressure data are shown. The tests were conducted with an inlet Mach number of 0.786 and a Reynolds number based on the inlet centerline velocity and exit diameter of 3.2 x 10(exp 6). The measured data are compared with previously published computational results. The ability of vortex generators to reduce circumferential total pressure distortion is demonstrated.
On the prestressing and deformation of rectangular particle detector frames
International Nuclear Information System (INIS)
Margulies, S.
1978-01-01
Particle detectors such as spark chambers and multiwire proportional chambers (MWPC) generally contain planar electrodes stretched across rectangular frames. For detectors of reasonable size, this can result in fairly large forces acting on the frames. To maintain the electrode planes under uniform tension and to prevent sagging, the frames must be prestressed. This paper contains a detailed examination of the deformation of rectangular frames under stress. A simple model for this phenomenon is presented. The model consists of treating each side of the frame as an elastic beam subject to the condition that the sides remain perpendicular at the corners. The predictions of the model are in good agreement with measured deflections of a MWPC frame. The model is used to determine the optimum value of a single concentrated prestressing force F to best approximate the total distributed force W of a uniformly tensed electrode plane. For most geometries it is found that F is about 62% of W. (Auth.)
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.
Relativistic energy-dispersion relations of 2D rectangular lattices
Ata, Engin; Demirhan, Doğan; Büyükkılıç, Fevzi
2017-04-01
An exactly solvable relativistic approach based on inseparable periodic well potentials is developed to obtain energy-dispersion relations of spin states of a single-electron in two-dimensional (2D) rectangular lattices. Commutation of axes transfer matrices is exploited to find energy dependencies of the wave vector components. From the trace of the lattice transfer matrix, energy-dispersion relations of conductance and valence states are obtained in transcendental form. Graphical solutions of relativistic and nonrelativistic transcendental energy-dispersion relations are plotted to compare how lattice parameters V0, core and interstitial size of the rectangular lattice affects to the energy-band structures in a situation core and interstitial diagonals are of equal slope.
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...
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.
Postbuckling Analysis Of A Rectangular Plate Loaded In Compression
Directory of Open Access Journals (Sweden)
Havran Jozef
2015-12-01
Full Text Available The stability analysis of a thin rectangular plate loaded in compression is presented. The nonlinear FEM equations are derived from the minimum total potential energy principle. The peculiarities of the effects of the initial imperfections are investigated using the user program. Special attention is paid to the influence of imperfections on the post-critical buckling mode. The FEM computer program using a 48 DOF element has been used for analysis. Full Newton-Raphson procedure has been applied.
Bandwidth Study of the Microwave Reflectors with Rectangular Corrugations
Zhang, Liang; He, Wenlong; Donaldson, Craig R.; Cross, Adrian W.
2016-09-01
The mode-selective microwave reflector with periodic rectangular corrugations in the inner surface of a circular metallic waveguide is studied in this paper. The relations between the bandwidth and reflection coefficient for different numbers of corrugation sections were studied through a global optimization method. Two types of reflectors were investigated. One does not consider the phase response and the other does. Both types of broadband reflectors operating at W-band were machined and measured to verify the numerical simulations.
Thermal stresses in rectangular plates: variational and finite element solutions
International Nuclear Information System (INIS)
Laura, P.A.A.; Gutierrez, R.H.; Sanchez Sarmiento, G.; Basombrio, F.G.
1978-01-01
This paper deals with the development of an approximate method for the analysis of thermal stresses in rectangular plates (plane stress problem) and an evaluation of the relative accuracy of the finite element method. The stress function is expanded in terms of polynomial coordinate functions which identically satisfy the boundary conditions, and a variational approach is used to determine the expansion coefficients. The results are in good agreement with a finite element approach. (Auth.)
Diffusion of heat from a finite, rectangular, plane heat source
International Nuclear Information System (INIS)
Ferreri, J.C.; Caballero, C.H.
1985-01-01
Non-dimensional results for the temperature field originating in a rectangular, finite, plane heat source with infinitesimal thickness are introduced. The source decays in time, zero decay being a particular case. Results are useful for obtaining an aproximation of the maximum temperature of a system holding an internal heat source. The range selected for the parameters is specially useful in the case of a nuclear waste repository. The application to the case of mass diffussion arises from analogy. (Author) [es
Basic study on the rectangular numeric keys for touch screen.
Harada, H; Katsuura, T; Kikuchi, Y
1997-06-01
The present study was conducted to examine the optimum inter-key spacing of numeric rectangular keys for touch screens. Six male students (22-25 years old) and three female students (21-24 years old) participated in the experiment. Each subject performed the data entry task using rectangular keys of touch devices. These keys were arranged in both horizontal and vertical layouts. The sizes of the rectangular keys in both layouts were 12 x 21 mm and 15 x 39 mm, and each of the inter-key spacing of each key was 0, 3, 6, 12 and 21 mm. The response time with inter-key spacing of 3 mm was significantly faster than with the inter-key spacing of 0, 12 and 21 mm (p < 0.05). Keys of vertical position produced faster response time than that of horizontal position. The subjective ratings showed that the inter-key spacing of 6 mm was significantly better than the inter-key spacing of 0, 3, 12 and 21 mm (p < 0.05).
Azimuthal critical heat flux in narrow rectangular channels
Energy Technology Data Exchange (ETDEWEB)
Kim, Yong Hoon; Noh, Sang Woo; Kim, Sung Joong; Suh, Kune Y. [Seoul National University, Seoul (Korea, Republic of)
2003-07-01
Tests were conducted to examine the critical heat flux (CHF) on the one-dimensional downward heating rectangular channel having a narrow gap by changing the orientation of the copper test heater assembly in a pool of saturated water under the atmospheric pressure. The test parameters include both the gap sizes of 1, 2, 5 and 10mm, and the surface orientation angles from the downward-facing position (180{sup o}) to the vertical position (90{sup o}), respectively. Also, the CHF experiments were performed for pool boiling with varying heater surface orientations in the unconfined space at the atmospheric pressure using the rectangular test section. It was observed that the CHF generally decreases as the surface inclination angle increases and as the gap size decreases. In consistency with several studies reported in the literature, it was found that there exists a transition angle above which the CHF changes with a rapid slope. An engineering correlation is developed for the CHF during natural convective boiling in the inclined, confined rectangular channels with the aid of dimensional analysis.
Rectangular superpolynomials for the figure-eight knot 41
Kononov, Ya. A.; Morozov, A. Yu.
2017-11-01
We rewrite the recently proposed differential expansion formula for HOMFLY polynomials of the knot 41 in an arbitrary rectangular representation R = [rs] as a sum over all Young subdiagrams λ of R with surprisingly simple coefficients of the Z factors. Intriguingly, these coefficients are constructed from the quantum dimensions of symmetric representations of the groups SL(r) and SL(s) and restrict the summation to diagrams with no more than s rows and r columns. Moreover, the β-deformation to Macdonald dimensions yields polynomials with positive integer coefficients, which are plausible candidates for the role of superpolynomials for rectangular representations. Both the polynomiality and the positivity of the coefficients are nonobvious, nevertheless true. This generalizes the previously known formulas for symmetric representations to arbitrary rectangular representations. The differential expansion allows introducing additional gradings. For the trefoil knot 31, to which our results for the knot 41 are immediately extended, we obtain the so-called fourth grading of hyperpolynomials. The property of factorization in roots of unity is preserved even in the five-graded case.
Augmented Beta rectangular regression models: A Bayesian perspective.
Wang, Jue; Luo, Sheng
2016-01-01
Mixed effects Beta regression models based on Beta distributions have been widely used to analyze longitudinal percentage or proportional data ranging between zero and one. However, Beta distributions are not flexible to extreme outliers or excessive events around tail areas, and they do not account for the presence of the boundary values zeros and ones because these values are not in the support of the Beta distributions. To address these issues, we propose a mixed effects model using Beta rectangular distribution and augment it with the probabilities of zero and one. We conduct extensive simulation studies to assess the performance of mixed effects models based on both the Beta and Beta rectangular distributions under various scenarios. The simulation studies suggest that the regression models based on Beta rectangular distributions improve the accuracy of parameter estimates in the presence of outliers and heavy tails. The proposed models are applied to the motivating Neuroprotection Exploratory Trials in Parkinson's Disease (PD) Long-term Study-1 (LS-1 study, n = 1741), developed by The National Institute of Neurological Disorders and Stroke Exploratory Trials in Parkinson's Disease (NINDS NET-PD) network. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Research on applications of rectangular beam in micro laser propulsion
International Nuclear Information System (INIS)
Jiao, L.; Cai, J.; Ma, H.H.; Li, G.X.; Li, L.; Shen, Z.W.; Tang, Z.P.
2014-01-01
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
International Nuclear Information System (INIS)
Choi, Chi Woong; Yu, Dong In; Kim, Moo Hwan
2010-01-01
There are two kinds of models in two-phase pressured drop; homogeneous flow model and separated flow model. Many previous researchers have developed correlations for two-phase pressure drop in a microchannel. Most correlations were modified Lockhart and Martinelli's correlation, which was based on the separated flow model. In this study, experiments for adiabatic liquid water and nitrogen gas flow in rectangular microchannels were conducted to investigate two-phase pressure drop in the rectangular microchannels. Two-phase frictional pressure drop in the rectangular microchannels is highly related with flow regime. Homogeneous model with six two-phase viscosity models: Owen(21)'s, MacAdams(22)'s, Cicchitti et al.(23)'s, Dukler et al.(24)'s, Beattie and Whalley(25)'s, Lin et al.(26)'s models and six separated flow models: Lockhart and Martinelli(27)'s, Chisholm(31)'s, Zhang et al.(15)'s, Lee and Lee(5)'s, Moriyama and Inue(4)'s, Qu and Mudawar(8)'s models were assessed with our experimental data. The best two-phase viscosity model is Beattie and Whalley's model. The best separated flow model is Qu and Mudawar's correlation. Flow regime dependency in both homogeneous and separated flow models was observed. Therefore, new flow pattern based correlations for both homogeneous and separated flow models were individually proposed
A comparison of Landsat point and rectangular field training sets for land-use classification
Tom, C. H.; Miller, L. D.
1984-01-01
Rectangular training fields of homogeneous spectroreflectance are commonly used in supervised pattern recognition efforts. Trial image classification with manually selected training sets gives irregular and misleading results due to statistical bias. A self-verifying, grid-sampled training point approach is proposed as a more statistically valid feature extraction technique. A systematic pixel sampling network of every ninth row and ninth column efficiently replaced the full image scene with smaller statistical vectors which preserved the necessary characteristics for classification. The composite second- and third-order average classification accuracy of 50.1 percent for 331,776 pixels in the full image substantially agreed with the 51 percent value predicted by the grid-sampled, 4,100-point training set.
Experimental study of gas-liquid flow local characteristics in rectangular microchannel
Directory of Open Access Journals (Sweden)
Bartkus German
2017-01-01
Full Text Available Using high-speed video recording and the method of dual laser scanning the gas-liquid flow was investigated in a rectangular microchannel with an aspect ratio of 0.74 (cross section 269×362 μm. The T-mixer was used at the channel’s inlet for the two-phase flow formation. The peculiarity of this work is using a number of liquids (ethanol, distilled water, 40% aqueous ethanol with different physical properties, including surface tension, viscosity, and density, with nitrogen. Experiments were carried out for the vertically upward and horizontal flow. Using laser scanning method the maps of flow patterns were obtained for all mixtures.
Laser--Doppler anemometry technique applied to two-phase dispersed flows in a rectangular channel
International Nuclear Information System (INIS)
Lee, S.L.; Srinivasan, J.
1979-01-01
A new optical technique using Laser--Doppler anemometry has been applied to the local measurement of turbulent upward flow of a dilute water droplet--air two-phase dispersion in a vertical rectangular channel. Individually examined were over 20,000 droplet signals coming from each of a total of ten transversely placed measuring points, the closest of which to the channel wall was 250 μ away from the wall. Two flows of different patterns due to different imposed flow conditions were investigated, one with and the other without a liquid film formed on the channel wall. Reported are the size and number density distribution and the axial and lateral velocity distributions for the droplets as well as the axial and lateral velocity distributions for the air
International Nuclear Information System (INIS)
Seki, Nobuhiro; Fukusako, Shoichiro; Inaba, Hideo
1978-01-01
In the present study the behavior of heat transfer in a rectangular cavity with one isothermal vertical wall heated and the other cooled is investigated. Heat transfer coefficients on the vertical walls are measured for fluids with Prandtl number Pr of 3 to 40,000 in case of aspect-ratio H/W from 5 to 47.5 and their correlated results are presented for laminar, transition and turbulent regions, respectively. It is shown that the present arrangement (Nu sub(H) - Ra sub(H)) using the height of cavity as a representative length may significantly be useful in the various heat transfer modes accompanied with flow patterns of them. (auth.)
Harmonic Suppressed Slot Antennas Using Rectangular/Circular Defected Ground Structures
Directory of Open Access Journals (Sweden)
Mohammad Saeid Ghaffarian
2012-01-01
Full Text Available Two wide rectangle-shaped microstrip-fed 2.6-GHz slot antennas using defected ground structures (DGSs with a low design complexity are proposed to achieve wideband harmonic suppression. To accomplish this, two rectangular DGSs (RDGSs in the first antenna and two circular DGSs (CDGSs in the second one with various dimensions are etched into the ground plane, which could have a wideband-stop characteristic. Simulated and measured reflection coefficients indicate that the two proposed structures effectively suppress the second and third harmonics up to 23 dB between 3.5 and 10.5 GHz with a maximum ripple of 2.4 dB. In addition, the radiation patterns and peak gains of the antennas can be suppressed at least 17 dB and 7.1 dBi, respectively, at the third harmonic frequency of 7.86 GHz.
Pohle, Ina; Niebisch, Michael; Müller, Hannes; Schümberg, Sabine; Zha, Tingting; Maurer, Thomas; Hinz, Christoph
2018-07-01
To simulate the impacts of within-storm rainfall variabilities on fast hydrological processes, long precipitation time series with high temporal resolution are required. Due to limited availability of observed data such time series are typically obtained from stochastic models. However, most existing rainfall models are limited in their ability to conserve rainfall event statistics which are relevant for hydrological processes. Poisson rectangular pulse models are widely applied to generate long time series of alternating precipitation events durations and mean intensities as well as interstorm period durations. Multiplicative microcanonical random cascade (MRC) models are used to disaggregate precipitation time series from coarse to fine temporal resolution. To overcome the inconsistencies between the temporal structure of the Poisson rectangular pulse model and the MRC model, we developed a new coupling approach by introducing two modifications to the MRC model. These modifications comprise (a) a modified cascade model ("constrained cascade") which preserves the event durations generated by the Poisson rectangular model by constraining the first and last interval of a precipitation event to contain precipitation and (b) continuous sigmoid functions of the multiplicative weights to consider the scale-dependency in the disaggregation of precipitation events of different durations. The constrained cascade model was evaluated in its ability to disaggregate observed precipitation events in comparison to existing MRC models. For that, we used a 20-year record of hourly precipitation at six stations across Germany. The constrained cascade model showed a pronounced better agreement with the observed data in terms of both the temporal pattern of the precipitation time series (e.g. the dry and wet spell durations and autocorrelations) and event characteristics (e.g. intra-event intermittency and intensity fluctuation within events). The constrained cascade model also
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.
Far-field potentials in cylindrical and rectangular volume conductors.
Dumitru, D; King, J C; Rogers, W E
1993-07-01
The occurrence of a transient dipole is one method of producing a far-field potential. This investigation qualitatively defines the characteristics of the near-field and far-field electrical potentials produced by a transient dipole in both cylindrical and rectangular volume conductors. Most body segments of electrophysiologic interest such as arms, legs, thorax, and neck are roughly cylindrical in shape. A centrally located dipole generator produces a nonzero equipotential region which is found to occur along the cylindrical wall at a distance from the dipole of approximately 1.4 times the cylinder's radius and 1.9 times the cylinder's radius for the center of the cylinder. This distance to the equi-potential zone along the surface wall expands but remains less than 3.0 times the cylindrical radius when the dipole is eccentrically placed. The magnitude of the equipotential region resulting from an asymmetrically placed dipole remains identical to that when the dipole is centrally located. This behavior is found to be very similar in rectangular shallow conducting volumes that model a longitudinal slice of the cylinder, thus allowing a simple experimental model of the cylinder to be utilized. Amplitudes of the equipotential region are inversely proportional to the cylindrical or rectangular volume's cross-sectional area at the location of dipolar imbalance. This study predicts that referential electrode montages, when placed at 3.0 times the radius or greater from a dipolar axially aligned far-field generator in cylindrical homogeneous volume conductors, will record only equipotential far-field effects.
Microwave corrosion detection using open ended rectangular waveguide sensors
Energy Technology Data Exchange (ETDEWEB)
Qaddoumi, N.; Handjojo, L.; Bigelow, T.; Easter, J.; Bray, A.; Zoughi, R.
2000-02-01
The use of microwave and millimeter wave nondestructive testing methods utilizing open ended rectangular waveguide sensors has shown great potential for detecting minute thickness variations in laminate structures, in particular those backed by a conducting plate. Slight variations in the dielectric properties of materials may also be detected using a set of optimal parameters which include the standoff distance and the frequency of operation. In a recent investigation, on detecting rust under paint, the dielectric properties of rust were assumed to be similar to those of Fe{sub 2}O{sub 3} powder. These values were used in an electromagnetic model that simulates the interaction of fields radiated by a rectangular waveguide aperture with layered structures to obtain optimal parameters. The dielectric properties of Fe{sub 2}O{sub 3} were measured to be very similar to the properties of paint. Nevertheless, the presence of a simulated Fe{sub 2}O{sub 3} layer under a paint layer was detected. In this paper the dielectric properties of several different rust samples from different environments are measured. The measurements indicate that the nature of real rust is quite diverse and is different from Fe{sub 2}O{sub 3} and paint, indicating that the presence of rust under paint can be easily detected. The same electromagnetic model is also used (with the newly measured dielectric properties of real rust) to obtain an optimal standoff distance at a frequency of 24 GHz. The results indicate that variations in the magnitude as well as the phase of the reflection coefficient can be used to obtain information about the presence of rust. An experimental investigation on detecting the presence of very thin rust layers (2.5--5 x 10{sup {minus}2} mm [09--2.0 x 10{sup {minus}3} in.]) using an open ended rectangular waveguide probe is also conducted. Microwave images of rusted specimens, obtained at 24 GHz, are also presented.
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 solved by an analytical calculation and the coupling between applied field, the demagnetization tensor field and spatially varying temperature is solved through iteration. We show that the demagnetizing field is of great importance in many cases and that it is necessary to take into account the non...
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.
Regimes of Two-Phase Flow in Short Rectangular Channel
Chinnov, Evgeny A.; Guzanov, Vladimir V.; Cheverda, Vyacheslav; Markovich, Dmitry M.; Kabov, Oleg A.
2009-08-01
Experimental study of two-phase flow in the short rectangular horizontal channel with height 440 μm has been performed. Characteristics of liquid motion inside the channel have been registered and measured by the Laser Induced Fluorescence technique. New information has allowed determining more precisely the characteristics of churn regime and boundaries between different regimes of two-phase flow. It was shown that formation of some two-phase flow regimes and transitions between them are determined by instability of the flow in the lateral parts of the channel.
Bubble departure diameter in narrow rectangular channel under rolling condition
Energy Technology Data Exchange (ETDEWEB)
Xie, T.; Chen, B.; Yan, X.; Xu, J.; Huang, Y.; Xiao, Z. [Nuclear Power Inst. of China, Chengdu, Sichuan (China)
2014-07-01
Forced convective subcooled boiling flow experiments were conducted in a vertical upward narrow rectangular channel under rolling motion. A high-speed digital video camera was used to capture the dynamics of the bubble nucleation process. Bubble departure diameters were obtained from the images. A bubble departure model based on force balance analysis was proposed to predict the bubble departure size under rolling condition by considering the additional centrifugal, tangential and Coriolis force. The proposed model agreed well with the experimental data within the averaged relative deviation of 5%. (author)
Experimental study of subsonic microjet escaping from a rectangular nozzle
Aniskin, V. M.; Maslov, A. A.; Mukhin, K. A.
2016-10-01
The first experiments on the subsonic laminar microjets escaping from the nozzles of rectangular shape are carried out. The nozzle size is 83.3x3823 microns. Reynolds number calculated by the nozzle height and the average flow velocity at the nozzle exit ranged from 58 to 154. The working gas was air at room temperature. The velocity decay and velocity fluctuations along the center line of the jet are determined. The fundamental difference between the laminar microjets characteristics and subsonic turbulent jets of macro size is shown. Based on measurements of velocity fluctuations it is shown the presence of laminar-turbulent transition in microjets and its location is determined.
Finite-size resonance dielectric cylinder in a rectangular waveguide
International Nuclear Information System (INIS)
Chuprina, V.N.; Khizhnyak, N.A.
1988-01-01
The problem on resonance spread of an electromagnetic wave by a dielectric circular cylinder of finite size in a rectangular waveguide is solved by a numerical-analytical method. The cylinder axes are parallel. The cylinder can be used as a resonance tuning element in accelerating SHF-sections. Problems on cutting off linear algebraic equation systems, to which relations of macroscopic electrodynamics in the integral differential form written for the concrete problem considered here are reduced by analytical transformations, are investigated in the stage of numerical analysis. Theoretical dependences of the insertion of the voltage standing wave coefficient on the generator wave length calculated for different values of problem parameters are constracted
Directory of Open Access Journals (Sweden)
Franz Konstantin Fuss
2013-09-01
Full Text Available This paper is a theoretical analysis of mirror tilt in a Michelson interferometer and its effect on the radiant flux over the active area of a rectangular photodetector or image sensor pixel. It is relevant to sensor applications using homodyne interferometry where these opto-electronic devices are employed for partial fringe counting. Formulas are derived for radiant flux across the detector for variable location within the fringe pattern and with varying wave front angle. The results indicate that the flux is a damped sine function of the wave front angle, with a decay constant of the ratio of wavelength to detector width. The modulation amplitude of the dynamic fringe pattern reduces to zero at wave front angles that are an integer multiple of this ratio and the results show that the polarity of the radiant flux changes exclusively at these multiples. Varying tilt angle causes radiant flux oscillations under an envelope curve, the frequency of which is dependent on the location of the detector with the fringe pattern. It is also shown that a fringe count of zero can be obtained for specific photodetector locations and wave front angles where the combined effect of fringe contraction and fringe tilt can have equal and opposite effects. Fringe tilt as a result of a wave front angle of 0.05° can introduce a phase measurement difference of 16° between a photodetector/pixel located 20 mm and one located 100 mm from the optical origin.
Applicability of electrical resistance tomography to rectangular vessels
International Nuclear Information System (INIS)
Ichijo, Noriaki; Matsuno, Shinsuke; Tokura, Susumu; Tochigi, Yoshikatsu; Misumi, Ryuta; Nishi, Kazuhiko; Kaminoyama, Meguru
2012-01-01
To ensure a stable operation of Joule-heated glass melters, it is necessary to observe the distribution of platinum group metal particles (noble metals) in molten glass. Electrical resistance tomography (ERT) has a potential to visualize the inside of the melter section because it can be applied at severe conditions such as high temperature and radioactive fields. Due to designing limitations, it is difficult to install electrodes on the wall of the glass melter. In addition, ERT is hardly applied to a rectangular section. To solve these problems, numerical and experimental studies have been implemented. To apply the ERT method, 8 electrodes are inserted from the top of the melter and set near the bottom to visualize the accumulation of noble metals on the bottom area. As a result of the numerical simulation and the experiment, it was clarified that the ERT can be applied to the rectangular vessel by inserting electrodes from the top of the vessel and has a potential to observe the accumulation of noble metals. (author)
Mechanical behavior analysis on electrostatically actuated rectangular microplates
Li, Zhikang; Zhao, Libo; Jiang, Zhuangde; Ye, Zhiying; Dai, Lu; Zhao, Yulong
2015-03-01
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.
Mechanical behavior analysis on electrostatically actuated rectangular microplates
International Nuclear Information System (INIS)
Li, Zhikang; Zhao, Libo; Jiang, Zhuangde; Ye, Zhiying; Zhao, Yulong; Dai, Lu
2015-01-01
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)
The calculation of dose rates from rectangular sources
International Nuclear Information System (INIS)
Hartley, B.M.
1998-01-01
A common problem in radiation protection is the calculation of dose rates from extended sources and irregular shapes. Dose rates are proportional to the solid angle subtended by the source at the point of measurement. Simple methods of calculating solid angles would assist in estimating dose rates from large area sources and therefore improve predictive dose estimates when planning work near such sources. The estimation of dose rates is of particular interest to producers of radioactive ores but other users of bulk radioactive materials may have similar interest. The use of spherical trigonometry can assist in determination of solid angles and a simple equation is derived here for the determination of the dose at any distance from a rectangular surface. The solid angle subtended by complex shapes can be determined by modelling the area as a patchwork of rectangular areas and summing the solid angles from each rectangle. The dose rates from bags of thorium bearing ores is of particular interest in Western Australia and measured dose rates from bags and containers of monazite are compared with theoretical estimates based on calculations of solid angle. The agreement is fair but more detailed measurements would be needed to confirm the agreement with theory. (author)
Measurement strategy for rectangular electrical capacitance tomography sensor
International Nuclear Information System (INIS)
Ye, Jiamin; Ge, Ruihuan; Qiu, Guizhi; Wang, Haigang
2014-01-01
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
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 on the cavitating vortex shedding behind rectangular obstacles
International Nuclear Information System (INIS)
Hegedus, F; Hos, C; Pandula, Z; Kullmann, L
2010-01-01
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.
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.
DEFF Research Database (Denmark)
Carrizosa, Emilio; Guerrero, Vanesa; Morales, Dolores Romero
2018-01-01
individuals as adjacent rectangular portions as possible and adding as few false adjacencies, i.e., adjacencies between rectangular portions corresponding to non-adjacent individuals, as possible. We formulate this visualization problem as a Mixed Integer Linear Programming (MILP) model. We propose......In this paper we address the problem of visualizing a frequency distribution and an adjacency relation 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...
Enhanced Circular Dichroism of Gold Bilayered Slit Arrays Embedded with Rectangular Holes.
Zhang, Hao; Wang, Yongkai; Luo, Lina; Wang, Haiqing; Zhang, Zhongyue
2017-01-01
Gold bilayered slit arrays with rectangular holes embedded into the metal surface are designed to enhance the circular dichroism (CD) effect of gold bilayered slit arrays. The rectangular holes in these arrays block electric currents and generate localized surface plasmons around these holes, thereby strengthening the CD effect. The CD enhancement factor depends strongly on the rotational angle and the structural parameters of the rectangular holes; this factor can be enhanced further by drilling two additional rectangular holes into the metal surfaces of the arrays. These results help facilitate the design of chiral structures to produce a strong CD effect and large electric fields.
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.
Calculation of control rods in rectangular reactor, and applications (1960)
International Nuclear Information System (INIS)
Goshen, S.; Pazy, A.
1960-01-01
The aim of this report is to find a method for estimating the anti-reactivity of control rods perpendicular to the axis in a cylindrical pile. The paper is divided into two parts. In the first is given a method of calculating control rods in a rectangular pile, similar to the Nordheim-Scalettar method for cylindrical piles. As an example the formulas are given for the theories of one and two neutron groups, the generalisation for several groups being evident. In the second part we find by a variation method a formula for estimating the Laplacian of a pile, which may be divided into parallelepipeds for which the Laplacian are given. Finally, this formula is used to calculate the anti-reactivity of rods perpendicular to the axis in a cylindrical pile. (author) [fr
Critical current studies of a HTS rectangular coil
Energy Technology Data Exchange (ETDEWEB)
Zhong, Z. [Department of Engineering, University of Cambridge (United Kingdom); Chudy, M., E-mail: Michal.chudy@stuba.sk [Graduate School of Technology Management, University of Pretoria (South Africa); Institute of Power and Applied Electrical Engineering, Slovak University of Technology in Bratislava (Slovakia); Ruiz, H.S. [Department of Engineering, University of Leicester, Leicester LE1 7RH (United Kingdom); Zhang, X.; Coombs, T. [Department of Engineering, University of Cambridge (United Kingdom)
2017-05-15
Highlights: • Unique square pancake coil was manufactured. • Measurements in relatively high magnetic field were performed. • Different sections of the coil were characterized. • Parts of the coil which are limiting critical current were identified. - Abstract: Nowadays, superconducting high field magnets are used in numerous applications due to their superior properties. High temperature superconductors (HTS) are usually used for production of circular pancake or racetrack coils. However different geometries of HTS coils might be required for some specific applications. In this study, the HTS coil wound on a rectangular frame was fully characterized in homogeneous DC background field. The study contains measurements of critical current angular dependencies. The critical current of the entire coil and two selected strands under different magnitudes and orientations of external magnetic fields are measured. The critical regions of the coil in different angular regimes are determined. This study brings better understanding of the in- field performance of HTS coils wound on frames with right-angles.
The nanosecond generator RG-1 with near-rectangular pulse
International Nuclear Information System (INIS)
Bulan, V.V.; Grabovskij, E.V.; Gribov, A.N.; Luzhnov, V.G.
1996-01-01
The 300 kV, 17 Ohm generator RG-1, which can deliver near-rectangular pulses with a pulse duration of 80 ns FWHM, is described. The polarity of the output pulse can be changed by a simple switch. The fast capacities of the Marx generator are used instead of the pulse forming line. Multi-spark gas switches were developed to decrease the inductance of the discharged circuit. The generator is supplied by a built-in high voltage source and its operation is controlled by a minicomputer. It is used the power supply-line 220 V. The RG-1 can be used in different modes of operation: gas discharge, particle beam formation, etc. (author). 4 figs., 3 refs
Stress analysis and evaluation of a rectangular pressure vessel
International Nuclear Information System (INIS)
Rezvani, M.A.; Ziada, H.H.; Shurrab, M.S.
1992-10-01
This study addresses structural analysis and evaluation of an abnormal rectangular pressure vessel, designed to house equipment for drilling and collecting samples from Hanford radioactive waste storage tanks. It had to be qualified according to ASME boiler and pressure vessel code, Section VIII; however, it had the cover plate bolted along the long face, a configuration not addressed by the code. Finite element method was used to calculate stresses resulting from internal pressure; these stresses were then used to evaluate and qualify the vessel. Fatigue is not a concern; thus, it can be built according to Section VIII, Division I instead of Division 2. Stress analysis was checked against the code. A stayed plate was added to stiffen the long side of the vessel
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.
Experimental study of natural circulation flow instability in rectangular channels
Energy Technology Data Exchange (ETDEWEB)
Zhou, Tao; Qi, Shi; Song, Mingqiang [North China Electric Power Univ., Beijing (China). School of Nuclear Science and Engineering; Passive Nuclear Safety Technology, Beijing (China). Beijing Key Lab.; Xiao, Zejun [Nuclear, Reactor Thermal Hydraulics Technology, Chengdu (China). CNNC Key Lab.
2017-05-15
Experiments of natural circulation flow instability were conducted in rectangular channels with 5 mm and 10 mm wide gaps. Results for different heating powers were obtained. The results showed that the flow will tend to be instable with the growing of heating power. The oscillation period of pressure D-value and volume flow are the same, but their phase positions are opposite. They both can be described by trigonometric functions. The existence of edge position and secondary flow will strengthen the disturbance of fluid flow in rectangle channels, which contributes to heat transfer. The disturbance of bubble and fluid will be strengthened, especially in the saturated boiling section, which make it possible for the mixing flow. The results also showed that the resistance in 5 mm channel is bigger than that in 10 mm channel, it is less likely to form stable natural circulation in the subcooled region.
The nanosecond generator RG-1 with near-rectangular pulse
Energy Technology Data Exchange (ETDEWEB)
Bulan, V V; Grabovskij, E V; Gribov, A N; Luzhnov, V G [TRINITI, Troitsk (Russian Federation)
1997-12-31
The 300 kV, 17 Ohm generator RG-1, which can deliver near-rectangular pulses with a pulse duration of 80 ns FWHM, is described. The polarity of the output pulse can be changed by a simple switch. The fast capacities of the Marx generator are used instead of the pulse forming line. Multi-spark gas switches were developed to decrease the inductance of the discharged circuit. The generator is supplied by a built-in high voltage source and its operation is controlled by a minicomputer. It is used the power supply-line 220 V. The RG-1 can be used in different modes of operation: gas discharge, particle beam formation, etc. (author). 4 figs., 3 refs.
Specific aspects of turbulent flow in rectangular ducts
Directory of Open Access Journals (Sweden)
Stanković Branislav D.
2017-01-01
Full Text Available The essential ideas of investigations of turbulent flow in a straight rectangular duct are chronologically presented. Fundamentally significant experimental and theoretical studies for mathematical modeling and numerical computations of this flow configuration are analyzed. An important physical aspect of this type of flow is presence of secondary motion in the plane perpendicular to the streamwise direction, which is of interest from both the engineering and the scientific viewpoints. The key facts for a task of turbulence modeling and optimal choice of the turbulence model are obtained through careful examination of physical mechanisms that generate secondary flows. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no.TR-33018: Increase in Energy and Ecology Efficiency of Processes in Pulverized Coal-Fired Furnace and Optimization of Utility Steam Boiler Air Pre-heater by Using In-House Developed Software Tools
Stability Analysis of Nonuniform Rectangular Beams Using Homotopy Perturbation Method
Directory of Open Access Journals (Sweden)
Seval Pinarbasi
2012-01-01
Full Text Available The design of slender beams, that is, beams with large laterally unsupported lengths, is commonly controlled by stability limit states. Beam buckling, also called “lateral torsional buckling,” is different from column buckling in that a beam not only displaces laterally but also twists about its axis during buckling. The coupling between twist and lateral displacement makes stability analysis of beams more complex than that of columns. For this reason, most of the analytical studies in the literature on beam stability are concentrated on simple cases: uniform beams with ideal boundary conditions and simple loadings. This paper shows that complex beam stability problems, such as lateral torsional buckling of rectangular beams with variable cross-sections, can successfully be solved using homotopy perturbation method (HPM.
Counter-current flow limited CHF in thin rectangular channels
International Nuclear Information System (INIS)
Cheng, L.Y.
1990-01-01
An analytical expression for counter-current-flow-limitation (CCFL) was used to predict critical heat flux (CHF) for downward flow in thin vertical rectangular channels which are prototypes of coolant channels in test and research nuclear reactors. Top flooding is the mechanism for counter-current flow limited CHF. The CCFL correlation also was used to determine the circulation and flooding-limited CHF. Good agreements were observed between the period the model predictions and data on the CHF for downflow. The minimum CHF for downflow is lower than the flooding-limited CHF and it is predicted to occur at a liquid flow rate higher than that at the flooding limit. 17 refs., 7 figs
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.
Free Vibration of Rectangular Plates with Attached Discrete Sprung Masses
Directory of Open Access Journals (Sweden)
Ding Zhou
2012-01-01
Full Text Available A direct approach is used to derive the exact solution for the free vibration of thin rectangular plates with discrete sprung masses attached. The plate is simply supported along two opposite edges and elastically supported along the two other edges. The elastic support can represent a range of boundary conditions from free to clamped supports. Considering only the compatibility of the internal forces between the plate and the sprung masses, the equations of the coupled vibration of the plate-spring-mass system are derived. The exact expressions for mode and frequency equations of the coupled vibration of the plate and sprung masses are determined. The solutions converge steadily and monotonically to exact values. The correctness and accuracy of the solutions are demonstrated through comparison with published results. A parametric study is undertaken focusing on the plate with one or two sprung masses. The results can be used as a benchmark for further investigation.
Magnethohydrodynamic surface and body waves in rectangular and cylindrical geometries
International Nuclear Information System (INIS)
Donnelly, I.J.
1982-03-01
Low frequency magnetohydrodynamic (MHD) waves are studied in both rectangular slab and cylindrical geometry cavities containing low β plasmas. The plasma density distribution is modelled by an inner region of constant density surrounded by an outer region of lower density and a conducting boundary. The wave frequencies and fields are obtained as functions of the density distribution and the wavenumber components k(parall) and k(perp). The lowest frequency wave mode is a surface wave in which the wave fields decrease in magnitude with distance from the interface between the two plasma densities. It has the properties of a shear wave when k(perp)/k(parall) is either small or large but is compressive when k(perp) is approximately equal to k(parall). The surface wave does not exist when k(perp) = 0. Higher frequency modes have the properties of fast magnetosonic waves, at least in the inner density region
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.
Performance analysis of SOI MOSFET with rectangular recessed channel
International Nuclear Information System (INIS)
Singh, M; Mishra, G P; Mishra, S; Mohanty, S S
2016-01-01
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. (paper)
Impedance of curved rectangular spiral coils around a conductive cylinder
Burke, S. K.; Ditchburn, R. J.; Theodoulidis, T. P.
2008-07-01
Eddy-current induction due to a thin conformable coil wrapped around a long conductive cylinder is examined using a second-order vector potential formalism. Compact closed-form expressions are derived for the self- and mutual impedances of curved rectangular spiral coils (i) in free space and (ii) when wrapped around the surface of the cylindrical rod. The validity of these expressions was tested against the results of a systematic series of experiments using a cylindrical Al-alloy rod and conformable coils manufactured using flexible printed-circuit-board technology. The theoretical expressions were in very good agreement with the experimental measurements. The significance of the results for eddy-current nondestructive inspection using flexible coils and flexible coil arrays is discussed.
Measurement of electron beam bunch phase length by rectangular cavities
International Nuclear Information System (INIS)
Afanas'ev, V.D.; Rudychev, V.G.; Ushakov, V.I.
1976-01-01
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
Inertial manipulation of bubbles in rectangular microfluidic channels.
Hadikhani, Pooria; Hashemi, S Mohammad H; Balestra, Gioele; Zhu, Lailai; Modestino, Miguel A; Gallaire, François; Psaltis, Demetri
2018-03-27
Inertial microfluidics is an active field of research that deals with crossflow positioning of the suspended entities in microflows. Until now, the majority of the studies have focused on the behavior of rigid particles in order to provide guidelines for microfluidic applications such as sorting and filtering. Deformable entities such as bubbles and droplets are considered in fewer studies despite their importance in multiphase microflows. In this paper, we show that the trajectory of bubbles flowing in rectangular and square microchannels can be controlled by tuning the balance of forces acting on them. A T-junction geometry is employed to introduce bubbles into a microchannel and analyze their lateral equilibrium position in a range of Reynolds (1 < Re < 40) and capillary numbers (0.1 < Ca < 1). We find that the Reynolds number (Re), the capillary number (Ca), the diameter of the bubble (D[combining macron]), and the aspect ratio of the channel are the influential parameters in this phenomenon. For instance, at high Re, the flow pushes the bubble towards the wall while large Ca or D[combining macron] moves the bubble towards the center. Moreover, in the shallow channels, having aspect ratios higher than one, the bubble moves towards the narrower sidewalls. One important outcome of this study is that the equilibrium position of bubbles in rectangular channels is different from that of solid particles. The experimental observations are in good agreement with the performed numerical simulations and provide insights into the dynamics of bubbles in laminar flows which can be utilized in the design of flow based multiphase flow reactors.
Directory of Open Access Journals (Sweden)
A. H. ELBATRAN
2015-07-01
Full Text Available Helical channels have a wide range of applications in petroleum engineering, nuclear, heat exchanger, chemical, mineral and polymer industries. They are used in the separation processes for fluids of different densities. The centrifugal force, free surface and geometrical effects of the helical channel make the flow pattern more complicated; hence it is very difficult to perform physical experiment to predict channel performance. Computational Fluid Dynamics (CFD can be suitable alternative for studying the flow pattern characteristics in helical channels. The different ranges of dimensional parameters, such as curvature and torsion, often cause various flow regimes in the helical channels. In this study, the effects of physical parameters such as curvature, torsion, Reynolds number, Froude number and Dean Number on the characteristics of the turbulent flow in helical rectangular channels have been investigated numerically, using a finite volume RANSE code Fluent of Ansys workbench 10.1 UTM licensed. The physical parameters were reported for range of curvature (δ of 0.16 to 0.51 and torsion (λ of 0.032 to 0.1 .The numerical results of this study showed that the decrease in the channel curvature and the increase in the channel torsion numbers led to the increase of the flow velocity inside the channel and the change in the shape of water free surface at given Dean, Reynolds and Froude numbers.
Visualization of pre-set vortices in boundary layer flow over wavy surface in rectangular channel
Budiman, Alexander Christantho
2014-12-04
Abstract: Smoke-wire flow visualization is used to study the development of pre-set counter-rotating streamwise vortices in boundary layer flow over a wavy surface in a rectangular channel. The formation of the vortices is indicated by the vortical structures on the cross-sectional plane normal to the wavy surface. To obtain uniform spanwise vortex wavelength which will result in uniform vortex size, two types of spanwise disturbances were used: a series of perturbation wires placed prior and normal to the leading edge of the wavy surface, and a jagged pattern in the form of uniform triangles cut at the leading edge. These perturbation wires and jagged pattern induce low-velocity streaks that result in the formation of counter-rotating streamwise vortices that evolve downstream to form the mushroom-like structures on the cross-sectional plane of the flow. The evolution of the most amplified disturbances can be attributed to the formation of these mushroom-like structures. It is also shown that the size of the mushroom-like structures depends on the channel entrance geometry, Reynolds number, and the channel gap.Graphical Abstract: [Figure not available: see fulltext.
Directory of Open Access Journals (Sweden)
Tao Chen
2015-01-01
Full Text Available The flexural behavior of rectangular hollow section (RHS steel beams with initial crack strengthened externally with carbon fiber reinforced polymer (CFRP plates was studied. Eight specimens were tested under three-point loading to failure. The experimental program included three beams as control specimens and five beams strengthened with CFRP plates with or without prestressing. The load deflection curves were graphed and failure patterns were observed. The yield loads and ultimate loads with or without repairing were compared together with the strain distributions of the CFRP plate. It was concluded that yield loads of cracked beams could be enhanced with repairing. Meanwhile, the ultimate loads were increased to some extent. The effect of repair became significant with the increase of the initial crack depth. The failure patterns of the repaired specimens were similar to those of the control ones. Mechanical clamping at the CFRP plate ends was necessary to avoid premature peeling between the CFRP plate and the steel beam. The stress levels in CFRP plates were relatively low during the tests. The use of prestressing could improve the utilization efficiency of CFRP plates. It could be concluded that the patching repair could be used to restore the load bearing capacity of the deficient steel beams.
Electrical Machines: Turn-to-Turn Capacitance in Formed Windings with Rectangular Cross-Section Wire
Djukic, Nenad; Encica, L.; Paulides, Johan
2015-01-01
Calculation of turn-to-turn capacitance (Ctt) in electrical machines (EMs) with formed windings with rectangular cross-section wire is presented. Three calculation methods are used for the calculation of Ctt in case of rectangular conductors – finite element (FE) method and two previously published
75 FR 82070 - Light-Walled Rectangular Pipe and Tube From China, Korea, and Mexico
2010-12-29
...-Walled Rectangular Pipe and Tube From China, Korea, and Mexico AGENCY: United States International Trade... from China, Korea, and Mexico that were found to be sold at less than fair value. Nacional de Acero S... panel proceeding in Light-Walled Rectangular Pipe and Tube from Mexico, USA-MEX-1904-04, to file...
77 FR 3497 - Light-Walled Rectangular Pipe and Tube From Taiwan
2012-01-24
... Rectangular Pipe and Tube From Taiwan Determination On the basis of the record \\1\\ developed in the subject... order on light-walled rectangular pipe and tube from Taiwan would be likely to lead to continuation or recurrence of material injury to an industry in the United States within a reasonably foreseeable time. \\1...
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.
Study on the output factors of asymmetrical rectangular electron beam field
International Nuclear Information System (INIS)
Chen Yinghai; Yang Yueqin; Ma Yuhong; Zheng Jin; Zou Lijuan
2009-01-01
Objective: To evaluate the variant regularity of the output factors of asymmetrical rectangular electron beam field. Methods: The output factors of three special fields with different applicators and energies were measured by ionization chamber method at different off-axis distances. Then deviations of the output factors between asymmetrical and symmetric rectangular fields were calculated. Results: The changes of output factor with different off-axis distances in asymmetrical rectangular fields were basically consistent with those in standard square fields with the same applicator. It revealed that the output factor of asymmetrical rectangular field was related with the off-axis ratio of standard square field. Applicator and field size did not show obvious influence on the output factor. Conclusions: The output factor changes of asymmetrical rectangular field are mainly correlated with the off-axis ratio of standard square field. The correction of the output factor is determined by the off-axis ratio changes in standard square field. (authors)
Analysis of junior high school students' difficulty in resolving rectangular conceptual problems
Utami, Aliksia Kristiana Dwi; Mardiyana, Pramudya, Ikrar
2017-08-01
Geometry is one part of the mathematics that must be learned in school and it has important effects on the development of creative thinking skills of learners, but in fact, there are some difficulties experienced by the students. This research focuses on analysis difficulty in resolving rectangular conceptual problems among junior high school students in every creative thinking skills level. This research used a descriptive method aimed to identify the difficulties and cause of the difficulties experienced by five students. The difficulties are associated with rectangular shapes and related problems. Data collection was done based on students' work through test, interview, and observations. The result revealed that student' difficulties in understanding the rectangular concept can be found at every creative thinking skills level. The difficulties are identifying the objects rectangular in the daily life except for a rectangle and square, analyzing the properties of rectangular shapes, and seeing the interrelationships between figures.
Lima, Rui; Wada, Shigeo; Tanaka, Shuji; Takeda, Motohiro; Ishikawa, Takuji; Tsubota, Ken-ichi; Imai, Yohsuke; Yamaguchi, Takami
2008-04-01
Progress in microfabricated technologies has attracted the attention of researchers in several areas, including microcirculation. Microfluidic devices are expected to provide powerful tools not only to better understand the biophysical behavior of blood flow in microvessels, but also for disease diagnosis. Such microfluidic devices for biomedical applications must be compatible with state-of-the-art flow measuring techniques, such as confocal microparticle image velocimetry (PIV). This confocal system has the ability to not only quantify flow patterns inside microchannels with high spatial and temporal resolution, but can also be used to obtain velocity measurements for several optically sectioned images along the depth of the microchannel. In this study, we investigated the ability to obtain velocity measurements using physiological saline (PS) and in vitro blood in a rectangular polydimethysiloxane (PDMS) microchannel (300 microm wide, 45 microm deep) using a confocal micro-PIV system. Applying this combination, measurements of trace particles seeded in the flow were performed for both fluids at a constant flow rate (Re = 0.02). Velocity profiles were acquired by successive measurements at different depth positions to obtain three-dimensional (3-D) information on the behavior of both fluid flows. Generally, the velocity profiles were found to be markedly blunt in the central region, mainly due to the low aspect ratio (h/w = 0.15) of the rectangular microchannel. Predictions using a theoretical model for the rectangular microchannel corresponded quite well with the experimental micro-PIV results for the PS fluid. However, for the in vitro blood with 20% hematocrit, small fluctuations were found in the velocity profiles. The present study clearly shows that confocal micro-PIV can be effectively integrated with a PDMS microchannel and used to obtain blood velocity profiles along the full depth of the microchannel because of its unique 3-D optical sectioning ability
Engineering the near-field imaging of a rectangular-lattice photonic-crystal slab in the second band
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Imaging properties of a two-dimensional rectangular-lattice photonic crystal (PC) slab consisting of air holes immersed in a dielectric are studied in this work. The field patterns of electromagnetic waves radiated from a point source through the PC slab are calculated with the finite-difference time-domain method. Comparing the field patterns with the corresponding equifrequency-surface contours simulated by the plane-wave expansion method, we find that an excellent-quality near-field image may be formed through the PC slab by the mechanisms of the simultaneous action of the self-collimation effect and the negative-refraction effect. Near-field imaging may be obtained within two different frequency regions in two vertical directions of the PC slab.
Directory of Open Access Journals (Sweden)
Bessem Samet
2011-09-01
Full Text Available Recently, Azam, Arshad and Beg [ Banach contraction principle on cone rectangular metric spaces, Appl. Anal. Discrete Math. 2009] introduced the notion of cone rectangular metric spaces by replacing the triangular inequality of a cone metric space by a rectangular inequality. In this paper, we introduce the notion of c-chainable cone rectangular metric space and we establish a fixed point theorem for uniformly locally contractive mappings in such spaces. An example is given to illustrate our obtained result.
Modelling of ultrasonic nondestructive testing in anisotropic materials - Rectangular crack
International Nuclear Information System (INIS)
Bostroem, A.
2001-12-01
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
2013-07-16
...-Walled Rectangular Pipe and Tube From China, Korea, Mexico, and Turkey: Notice of Commission... countervailing duty order on light-walled rectangular pipe and tube from China and the antidumping duty orders on light-walled rectangular pipe and tube from China, Korea, Mexico, and Turkey would be likely to lead to...
2013-12-10
...-Walled Rectangular Pipe and Tube From China, Korea, Mexico, and Turkey; Scheduling of Full Five-Year... the Antidumping Duty Orders on Light-Walled Rectangular Pipe and Tube From China, Korea, Mexico, and... on light- walled rectangular pipe and tube from China, Korea, Mexico, and Turkey would be likely to...
International Nuclear Information System (INIS)
Usui, Tohru; Kaminaga, Masanori; Sudo, Yukio.
1988-07-01
Quantitative understanding of critical heat flux (CHF) in the narrow vertical rectangular channel is required for the thermo-hydroulic design and the safety analysis of research reactors in which flat-plate-type fuel is adopted. Especially, critical heat flux under low downward velocity has a close relation with falling water limitation under counter-current flow. Accordingly, CCFL (Counter-current Flow Limitation) experiments were carried out for both vertical rectangular channels and vertical circular tubes varried in their size and configuration of their cross sections, to make clear CCFL characteristics in the vertical rectangular channels. In the experiments, l/de of the rectangular channel was changed from 3.5 to 180. As the results, it was clear that different equivalent hydraulic diameter de, namely width or water gap of channel, gave different CCFL characteristics of rectangular channel. But the influence of channel length l on CCFL characteristics was not observed. Besides, a dimensionless correlation to estimate a relation between upward air velocity and downward water velocity was proposed based on the present experimental results. The difference of CCFL characteristics between rectangular channels and circular tubes was also investigated. Especially for the rectangular channels, dry-patches appearing condition was made clear as a flow-map. (author)
International Nuclear Information System (INIS)
Beckermann, C.; Ramadhyani, S.; Viskanta, R.
1986-01-01
A numerical and experimental study is performed to analyze the steady-state natural convection fluid flow and heat transfer in a vertical rectangular enclosure that is partially filled with a vertical layer of a fluid-saturated porous medium. The flow in the porous layer is modeled utilizing the Brinkman-Forchheimer-extended Darcy equations. The numerical model is verified by conducting a number of experiments with spherical glass beads as the porous medium and water and glycerin as the fluids in rectangular test-cells. The agreement between the flow visualization results and temperature measurements and the numerical model is, in general, good. It is found that the amount of fluid penetrating from the fluid region into the porous layer depends strongly on the Darcy (Da) and Rayleigh (Ra) numbers. For a relatively low product of Ra x Da, the flow takes place primarily in the fluid layer, and heat transfer in the porous layer is by conduction only. On the other hand, fluid penetrating into a relatively highly permeable porous layer has a significant impact on the natural convection flow patterns in the entire enclosure
Permuting sparse rectangular matrices into block-diagonal form
Energy Technology Data Exchange (ETDEWEB)
Aykanat, Cevdet; Pinar, Ali; Catalyurek, Umit V.
2002-12-09
This work investigates the problem of permuting a sparse rectangular matrix into block diagonal form. Block diagonal form of a matrix grants an inherent parallelism for the solution of the deriving problem, as recently investigated in the context of mathematical programming, LU factorization and QR factorization. We propose graph and hypergraph models to represent the nonzero structure of a matrix, which reduce the permutation problem to those of graph partitioning by vertex separator and hypergraph partitioning, respectively. Besides proposing the models to represent sparse matrices and investigating related combinatorial problems, we provide a detailed survey of relevant literature to bridge the gap between different societies, investigate existing techniques for partitioning and propose new ones, and finally present a thorough empirical study of these techniques. Our experiments on a wide range of matrices, using state-of-the-art graph and hypergraph partitioning tools MeTiS and PaT oH, revealed that the proposed methods yield very effective solutions both in terms of solution quality and run time.
Interaction of weak shock waves with rectangular meshes in plate
Directory of Open Access Journals (Sweden)
O.A. Mikulich
2016-09-01
Full Text Available In mechanical engineering, building and other industries a significant part of the process includes the presence of various dynamic loads due to technological and mechanical impacts. Consideration of such load effects allows more accurate assessment of the structural elements strength or machine parts. Aim: The aim is to develop an algorithm for calculating of dynamic stress state of plates with meshes for pulse loading in the form of a weak shock wave. Materials and Methods: An integral and discrete Fourier transform were used to solve the problem. An application of Fourier transform by time allowed reducing the dynamic problem of flat deformation to the solution of a finite number of problems for the established oscillations at fixed cyclic frequency values. In the area of Fourier-images the method of boundary integral equations and the apparatus of a complex variable function theory are used to study the dynamic stress concentration. Results: Based on the developed methodology the distribution change of the dynamic circle stress over time on the edge of a rectangular hole is studied. The time sections of stress distribution fields under the influence of pulse dynamic load is constructed.
Modal density of rectangular structures in a wide frequency range
Parrinello, A.; Ghiringhelli, G. L.
2018-04-01
A novel approach to investigate the modal density of a rectangular structure in a wide frequency range is presented. First, the modal density is derived, in the whole frequency range of interest, on the basis of sound transmission through the infinite counterpart of the structure; then, it is corrected by means of the low-frequency modal behavior of the structure, taking into account actual size and boundary conditions. A statistical analysis reveals the connection between the modal density of the structure and the transmission of sound through its thickness. A transfer matrix approach is used to compute the required acoustic parameters, making it possible to deal with structures having arbitrary stratifications of different layers. A finite element method is applied on coarse grids to derive the first few eigenfrequencies required to correct the modal density. Both the transfer matrix approach and the coarse grids involved in the finite element analysis grant high efficiency. Comparison with alternative formulations demonstrates the effectiveness of the proposed methodology.
Compressibility effects in the shear layer over a rectangular cavity
Energy Technology Data Exchange (ETDEWEB)
Beresh, Steven J.; Wagner, Justin; Casper, Katya Marie
2016-10-26
we studied the influence of compressibility on the shear layer over a rectangular cavity of variable width in a free stream Mach number range of 0.6–2.5 using particle image velocimetry data in the streamwise centre plane. As the Mach number increases, the vertical component of the turbulence intensity diminishes modestly in the widest cavity, but the two narrower cavities show a more substantial drop in all three components as well as the turbulent shear stress. Furthermore, this contrasts with canonical free shear layers, which show significant reductions in only the vertical component and the turbulent shear stress due to compressibility. The vorticity thickness of the cavity shear layer grows rapidly as it initially develops, then transitions to a slower growth rate once its instability saturates. When normalized by their estimated incompressible values, the growth rates prior to saturation display the classic compressibility effect of suppression as the convective Mach number rises, in excellent agreement with comparable free shear layer data. The specific trend of the reduction in growth rate due to compressibility is modified by the cavity width.
Attenuation in Rectangular Waveguides with Finite Conductivity Walls
Directory of Open Access Journals (Sweden)
K. C. Yeong
2011-06-01
Full Text Available We present a fundamental and accurate approach to compute the attenuation of electromagnetic waves propagating in rectangular waveguides with finite conductivity walls. The wavenumbers kx and ky in the x and y directions respectively, are obtained as roots of a set of transcendental equations derived by matching the tangential component of the electric field (E and the magnetic field (H at the surface of the waveguide walls. The electrical properties of the wall material are determined by the complex permittivity ε, permeability μ, and conductivity σ. We have examined the validity of our model by carrying out measurements on the loss arising from the fundamental TE10 mode near the cutoff frequency. We also found good agreement between our results and those obtained by others including Papadopoulos’ perturbation method across a wide range of frequencies, in particular in the vicinity of cutoff. In the presence of degenerate modes however, our method gives higher losses, which we attribute to the coupling between modes as a result of dispersion.
Propagation of spiral waves pinned to circular and rectangular obstacles.
Sutthiopad, Malee; Luengviriya, Jiraporn; Porjai, Porramain; Phantu, Metinee; Kanchanawarin, Jarin; Müller, Stefan C; Luengviriya, Chaiya
2015-05-01
We present an investigation of spiral waves pinned to circular and rectangular obstacles with different circumferences in both thin layers of the Belousov-Zhabotinsky reaction and numerical simulations with the Oregonator model. For circular objects, the area always increases with the circumference. In contrast, we varied the circumference of rectangles with equal areas by adjusting their width w and height h. For both obstacle forms, the propagating parameters (i.e., wavelength, wave period, and velocity of pinned spiral waves) increase with the circumference, regardless of the obstacle area. Despite these common features of the parameters, the forms of pinned spiral waves depend on the obstacle shapes. The structures of spiral waves pinned to circles as well as rectangles with the ratio w/h∼1 are similar to Archimedean spirals. When w/h increases, deformations of the spiral shapes are observed. For extremely thin rectangles with w/h≫1, these shapes can be constructed by employing semicircles with different radii which relate to the obstacle width and the core diameter of free spirals.
LEDA 074886: A REMARKABLE RECTANGULAR-LOOKING GALAXY
International Nuclear Information System (INIS)
Graham, Alister W.; Spitler, Lee R.; Forbes, Duncan A.; Lisker, Thorsten; Janz, Joachim; Moore, Ben
2012-01-01
We report the discovery of an interesting and rare rectangular-shaped galaxy. At a distance of 21 Mpc, the dwarf galaxy LEDA 074886 has an absolute R-band magnitude of –17.3 mag. Adding to this galaxy's intrigue is the presence of an embedded, edge-on stellar disk (of extent 2 R e,disk = 12'' = 1.2 kpc) for which Forbes et al. reported v rot /σ ≈ 1.4. We speculate that this galaxy may be the remnant of two (nearly edge-on) merged disk galaxies in which the initial gas was driven inward and subsequently formed the inner disk, while the stars at larger radii effectively experienced a dissipationless merger event resulting in this 'emerald cut galaxy' having very boxy isophotes with a 4 /a = –0.05 to –0.08 from 3 to 5 kpc. This galaxy suggests that knowledge from simulations of both 'wet' and 'dry' galaxy mergers may need to be combined to properly understand the various paths that galaxy evolution can take, with a particular relevance to blue elliptical galaxies.
Preliminary Study of ONB in Narrow-Vertical Rectangular Channel
International Nuclear Information System (INIS)
Omar, S. AL-Yahia; Jo, Daeseong
2015-01-01
The location where the vapor bubble can first exist at the heated surface is called 'onset of nucleate boiling (ONB). The subcooled boiling is highly efficient to remove the heat owing to the high heat transfer coefficient. The heat transfer is affected by the motion of the bulk liquid as well as the latent heat transport of the liquid microlayer between the bubble and the heated wall. However, with increasing in the wall temperature, the bubble growth will increase and may they aggregate at the heated surface forming a vapor film, which will prevent the heat transport from the wall and that leads to highly rise in wall temperature. This phenomenon called departure from nucleate boiling (DNB). Many experimental and numerical CFD methods were carried out to investigate the subcooled boiling because of its importance in the industrial applications. In the present study, vertical narrow rectangular channel heated from both side was simulated by using CFX-14 to investigate the subcooled wall boiling, and identical simulation is done by using TMAP to compare the ONB location between numerical simulation and empirical correlations that implemented in TMAP. The numerical results using CFX-14 are discussed and compared with the results obtained from TMAP. The coolant temperature increases gradually (linearly) in the downward direction owing to the uniform applied heat flux.
Preliminary Study of ONB in Narrow-Vertical Rectangular Channel
Energy Technology Data Exchange (ETDEWEB)
Omar, S. AL-Yahia; Jo, Daeseong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2015-10-15
The location where the vapor bubble can first exist at the heated surface is called 'onset of nucleate boiling (ONB). The subcooled boiling is highly efficient to remove the heat owing to the high heat transfer coefficient. The heat transfer is affected by the motion of the bulk liquid as well as the latent heat transport of the liquid microlayer between the bubble and the heated wall. However, with increasing in the wall temperature, the bubble growth will increase and may they aggregate at the heated surface forming a vapor film, which will prevent the heat transport from the wall and that leads to highly rise in wall temperature. This phenomenon called departure from nucleate boiling (DNB). Many experimental and numerical CFD methods were carried out to investigate the subcooled boiling because of its importance in the industrial applications. In the present study, vertical narrow rectangular channel heated from both side was simulated by using CFX-14 to investigate the subcooled wall boiling, and identical simulation is done by using TMAP to compare the ONB location between numerical simulation and empirical correlations that implemented in TMAP. The numerical results using CFX-14 are discussed and compared with the results obtained from TMAP. The coolant temperature increases gradually (linearly) in the downward direction owing to the uniform applied heat flux.
Computation of rectangular source integral by rational parameter polynomial method
International Nuclear Information System (INIS)
Prabha, Hem
2001-01-01
Hubbell et al. (J. Res. Nat Bureau Standards 64C, (1960) 121) have obtained a series expansion for the calculation of the radiation field generated by a plane isotropic rectangular source (plaque), in which leading term is the integral H(a,b). In this paper another integral I(a,b), which is related with the integral H(a,b) has been solved by the rational parameter polynomial method. From I(a,b), we compute H(a,b). Using this method the integral I(a,b) is expressed in the form of a polynomial of a rational parameter. Generally, a function f (x) is expressed in terms of x. In this method this is expressed in terms of x/(1+x). In this way, the accuracy of the expression is good over a wide range of x as compared to the earlier approach. The results for I(a,b) and H(a,b) are given for a sixth degree polynomial and are found to be in good agreement with the results obtained by numerically integrating the integral. Accuracy could be increased either by increasing the degree of the polynomial or by dividing the range of integration. The results of H(a,b) and I(a,b) are given for values of b and a up to 2.0 and 20.0, respectively
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...... area and adjacency requirements, this visualization problem is formulated as a three-objective Mixed Integer Nonlinear Problem. The first objective seeks to maximize the number of true adjacencies that the rectangular map is able to reproduce, the second one is to minimize the number of false...
Chremmos, Ioannis
2010-01-01
The scattering of a surface plasmon polariton (SPP) by a rectangular dielectric channel discontinuity is analyzed through a rigorous magnetic field integral equation method. The scattering phenomenon is formulated by means of the magnetic-type scalar integral equation, which is subsequently treated through an entire-domain Galerkin method of moments (MoM), based on a Fourier-series plane wave expansion of the magnetic field inside the discontinuity. The use of Green's function Fourier transform allows all integrations over the area and along the boundary of the discontinuity to be performed analytically, resulting in a MoM matrix with entries that are expressed as spectral integrals of closed-form expressions. Complex analysis techniques, such as Cauchy's residue theorem and the saddle-point method, are applied to obtain the amplitudes of the transmitted and reflected SPP modes and the radiated field pattern. Through numerical results, we examine the wavelength selectivity of transmission and reflection against the channel dimensions as well as the sensitivity to changes in the refractive index of the discontinuity, which is useful for sensing applications.
Two-dimensional flow characteristics of wave interactions with a free-rolling rectangular structure
Energy Technology Data Exchange (ETDEWEB)
Kwang Hyo Jung; Kuang-An Chang [Texas A and M University, College Station, TX (United States). Dept. of Civil Engineering; Huang, E.T. [Naval Facilities Engineering Service Center, Port Hueneme, CA (United States). Amphibious System Div.
2005-01-01
This paper presents laboratory observations of flow characteristics for regular waves passing a rectangular structure in a two-dimensional wave tank. The structure with a draft one-half of its height was hinged at the center of gravity and free to roll (one degree of freedom) by waves. Particle image velocimetry (PIV) was used to measure the velocity field in the vicinity of the structure. The mean velocity and turbulence properties were obtained by phase-averaging the PIV velocity maps from repeated test runs. Since the viscous damping (also called the eddy making damping) in a vortical flow affects the roll motion of a blunt body, the quantitative flow pattern was represented to elucidate the coupled interactions between the body motion and the waves. Additionally, the turbulence properties including the turbulence length scale and the turbulent kinetic energy budget were investigated to characterize the interactions. The results show that vortices were generated near the structure corners at locations opposing to that of the roll damping effect for waves with a period longer than the roll natural period of the structure. (Author)
Two dimensional heat transfer problem in flow boiling in a rectangular minichannel
Directory of Open Access Journals (Sweden)
Hożejowska Sylwia
2015-01-01
Full Text Available The paper presents mathematical modelling of flow boiling heat transfer in a rectangular minichannel asymmetrically heated by a thin and one-sided enhanced foil. Both surfaces are available for observations due to the openings covered with glass sheets. Thus, changes in the colour of the plain foil surface can be registered and then processed. Plain side of the heating foil is covered with a base coat and liquid crystal paint. Observation of the opposite, enhanced surface of the minichannel allows for identification of the gas-liquid two-phase flow patterns and vapour quality. A two-dimensional mathematical model of heat transfer in three subsequent layers (sheet glass, heating foil, liquid was proposed. Heat transfer in all these layers was described with the respective equations: Laplace equation, Poisson equation and energy equation, subject to boundary conditions corresponding to the observed physical process. The solutions (temperature distributions in all three layers were obtained by Trefftz method. Additionally, the temperature of the boiling liquid was obtained by homotopy perturbation method (HPM combined with Trefftz method. The heat transfer coefficient, derived from Robin boundary condition, was estimated in both approaches. In comparison, the results by both methods show very good agreement especially when restricted to the thermal sublayer.
Rectangular Ring Antenna Excited by Circular Disc Monopole for WiMAX System
Directory of Open Access Journals (Sweden)
Souphanna Vongsack
2014-01-01
Full Text Available This research presents a rectangular ring antenna excited by a circular disc monopole (CDM mounted in front of a square reflector. The proposed antenna is designed to cover a frequency range of 2.300–5.825 GHz and thereby is suitable for WiMAX applications. Multiple parametric studies were carried out using the CST Microwave Studio simulation program. A prototype antenna was fabricated and experimented. The measurements were taken and compared with the simulation results, which indicates good agreement between both results. The prototype antenna produces an impedance bandwidth (|S11| < −10 dB that covers the WiMAX frequency range and a constant unidirectional radiation pattern (θ=0° and ∅=90°. The minimum and maximum gains are 3.7 and 8.7 dBi, respectively. The proposed antenna is of compact size and has good unidirectional radiation performance. Thus, it is very suitable for a multitude of WiMAX applications.
Evaporation of liquids on chemically patterned surfaces
Vieyra Salas, J.A.; Darhuber, A.A.
2011-01-01
We studied evaporation rates of volatile liquids deposited onto chemically patterned surfaces by means of experiments and numerical simulations. We quantified the influence of the droplet geometry, in particular circular, triangular, rectangular and square shapes, as well as the influence of contact
Investigation of process induced warpage for pultrusion of a rectangular hollow profile
DEFF Research Database (Denmark)
Baran, Ismet; Hattel, Jesper Henri; Akkerman, Remko
2015-01-01
A novel thermo-chemical–mechanical analysis of the pultrusion process is presented. A process simulation is performed for an industrially pultruded rectangular hollow profile containing both unidirectional (UD) roving and continuous filament mat (CFM) layers. The reinforcements are impregnated...
Taha, T.J.; Lefferts, Leonardus; van der Meer, Theodorus H.
2016-01-01
An experimental heat transfer investigation was carried out to examine the influence of carbon nanotubes (CNTs) layer deposits on the convective heat transfer performance inside rectangular microchannels. Successful synthesis of vertically aligned CNTs was achieved using a catalytic vapor deposition
Nonlinear Mechanics of MEMS Rectangular Microplates under Electrostatic Actuation
Saghir, Shahid
2016-12-01
The first objective of the dissertation is to develop a suitable reduced order model capable of investigating the nonlinear mechanical behavior of von-Karman plates under electrostatic actuation. The second objective is to investigate the nonlinear static and dynamic behavior of rectangular microplates under small and large actuating forces. In the first part, we present and compare various approaches to develop reduced order models for the nonlinear von-Karman rectangular microplates actuated by nonlinear electrostatic forces. The reduced-order models aim to investigate the static and dynamic behavior of the plate under small and large actuation forces. A fully clamped microplate is considered. Different types of basis functions are used in conjunction with the Galerkin method to discretize the governing equations. First we investigate the convergence with the number of modes retained in the model. Then for validation purpose, a comparison of the static results is made with the results calculated by a nonlinear finite element model. The linear eigenvalue problem for the plate under the electrostatic force is solved for a wide range of voltages up to pull-in. In the second part, we present an investigation of the static and dynamic behavior of a fully clamped microplate. We investigate the effect of different non-dimensional design parameters on the static response. The forced-vibration response of the plate is then investigated when the plate is excited by a harmonic AC load superimposed to a DC load. The dynamic behavior is examined near the primary and secondary (superharmonic and subharmonic) resonances. The microplate shows a strong hardening behavior due to the cubic nonlinearity of midplane stretching. However, the behavior switches to softening as the DC load is increased. Next, near-square plates are studied to understand the effect of geometric imperfections of microplates. In the final part of the dissertation, we investigate the mechanical behavior of
Rapid State Space Modeling Tool for Rectangular Wing Aeroservoelastic Studies
Suh, Peter M.; Conyers, Howard Jason; Mavris, Dimitri N.
2015-01-01
This report introduces a modeling and simulation tool for aeroservoelastic analysis of rectangular wings with trailing-edge control surfaces. The inputs to the code are planform design parameters such as wing span, aspect ratio, and number of control surfaces. Using this information, the generalized forces are computed using the doublet-lattice method. Using Roger's approximation, a rational function approximation is computed. The output, computed in a few seconds, is a state space aeroservoelastic model which can be used for analysis and control design. The tool is fully parameterized with default information so there is little required interaction with the model developer. All parameters can be easily modified if desired. The focus of this report is on tool presentation, verification, and validation. These processes are carried out in stages throughout the report. The rational function approximation is verified against computed generalized forces for a plate model. A model composed of finite element plates is compared to a modal analysis from commercial software and an independently conducted experimental ground vibration test analysis. Aeroservoelastic analysis is the ultimate goal of this tool, therefore, the flutter speed and frequency for a clamped plate are computed using damping-versus-velocity and frequency-versus-velocity analysis. The computational results are compared to a previously published computational analysis and wind-tunnel results for the same structure. A case study of a generic wing model with a single control surface is presented. Verification of the state space model is presented in comparison to damping-versus-velocity and frequency-versus-velocity analysis, including the analysis of the model in response to a 1-cos gust.
Experimental study of critical heat flux in inclined rectangular gap
International Nuclear Information System (INIS)
Kim, S.J.; Kim, Y.H.; Noh, S.W.; Suh, K.Y.; Rempe, J.L.; Cheung, F.B.; Kim, S.B.
2003-01-01
In the TMI-2 accident, the lower part of the reactor pressure vessel was overheated and then rather rapidly cooled down, as was later found out in a vessel investigation project. This accounted for the possibility of gap cooling feasibility. For this reason, a great deal of investigations was performed to determine the critical heat flux (CHF) from the standpoint of in-vessel retention (IVR). As part of a joint Korean-U.S. International Nuclear Energy Research Initiative (INERI) project, Tests were conducted to examine the critical heat flux (CHF) on the one-dimensional downward heating rectangular channel having a narrow gap by changing the orientation of the copper test heater assembly in a pool of saturated water under the atmospheric pressure. The test parameters include both the gap sizes of 1, 2, 5 and 10 mm, and the surface orientation angles from the downward-facing position (180deg) to the vertical position (90deg), respectively. It was observed that the CHF generally decreases as the surface inclination angle increases and as the gap size decreases. However, in downward-facing position (180deg), somewhat differing results were detected relative to previous reports. For a certain gap size having a similar dimension with vapor layer thickness, more efficient heat transfer was detected and this may be interpreted by characteristic property such as the vapor layer thickness of water. In consistency with several studies reported in the literature, it was found that there exists a transition angle above that the CHF changes with a rapid slope. (author)
Turbulent subcooled boiling flow visualization experiments through a rectangular channel
International Nuclear Information System (INIS)
Estrada-Perez, Carlos E.; Dominguez-Ontiveros, Elvis E.; Hassan, Yassin A.
2008-01-01
Full text of publication follows: Proper characterization of subcooled boiling flow is of importance in many applications. It is of exceptional significance in the development of empirical models for the design of nuclear reactors, steam generators, and refrigeration systems. Most of these models are based on experimental studies that share the characteristics of utilizing point measurement probes with high temporal resolution, e.g. Hot Film Anemometry (HFA), Laser Doppler Velocimetry (LDV), and Fiber Optic Probes (FOP). However there appears to be a scarcity of experimental studies that can capture instantaneous whole-field measurements with a fast time response. Particle Tracking Velocimetry (PTV) may be used to overcome the limitations associated with point measurement techniques. PTV is a whole-flow-field technique providing instantaneous velocity vectors capable of high spatial and temporal resolution. PTV is also an exceptional tool for the analysis of boiling flow due to its ability to differentiate between the gas and liquid phases and subsequently deliver independent velocity fields associated with each phase. In this work, using PTV, liquid velocity fields of a turbulent subcooled boiling flow in a rectangular channel were successfully obtained. The present results agree with similar studies that used point measurement probes. However, the present study provides additional information; not only averaged profiles of the velocity components were obtained, instantaneous 2-D velocity fields were also readily available with a high temporal and spatial resolution. Analysis of fluctuating velocities, Reynolds stresses, and higher order statistics of the flow are presented. This work is an attempt to enrich the database already collected on turbulent subcooled boiling flow, with the hope that it will be useful in turbulence modeling efforts. (authors)
Psyplot: Visualizing rectangular and triangular Climate Model Data with Python
Sommer, Philipp
2016-04-01
The development and use of climate models often requires the visualization of geo-referenced data. Creating visualizations should be fast, attractive, flexible, easily applicable and easily reproducible. There is a wide range of software tools available for visualizing raster data, but they often are inaccessible to many users (e.g. because they are difficult to use in a script or have low flexibility). In order to facilitate easy visualization of geo-referenced data, we developed a new framework called "psyplot," which can aid earth system scientists with their daily work. It is purely written in the programming language Python and primarily built upon the python packages matplotlib, cartopy and xray. The package can visualize data stored on the hard disk (e.g. NetCDF, GeoTIFF, any other file format supported by the xray package), or directly from the memory or Climate Data Operators (CDOs). Furthermore, data can be visualized on a rectangular grid (following or not following the CF Conventions) and on a triangular grid (following the CF or UGRID Conventions). Psyplot visualizes 2D scalar and vector fields, enabling the user to easily manage and format multiple plots at the same time, and to export the plots into all common picture formats and movies covered by the matplotlib package. The package can currently be used in an interactive python session or in python scripts, and will soon be developed for use with a graphical user interface (GUI). Finally, the psyplot framework enables flexible configuration, allows easy integration into other scripts that uses matplotlib, and provides a flexible foundation for further development.
Thermal vibration of a rectangular single-layered graphene sheet with quantum effects
International Nuclear Information System (INIS)
Wang, Lifeng; Hu, Haiyan
2014-01-01
The thermal vibration of a rectangular single-layered graphene sheet is investigated by using a rectangular nonlocal elastic plate model with quantum effects taken into account when the law of energy equipartition is unreliable. The relation between the temperature and the Root of Mean Squared (RMS) amplitude of vibration at any point of the rectangular single-layered graphene sheet in simply supported case is derived first from the rectangular nonlocal elastic plate model with the strain gradient of the second order taken into consideration so as to characterize the effect of microstructure of the graphene sheet. Then, the RMS amplitude of thermal vibration of a rectangular single-layered graphene sheet simply supported on an elastic foundation is derived. The study shows that the RMS amplitude of the rectangular single-layered graphene sheet predicted from the quantum theory is lower than that predicted from the law of energy equipartition. The maximal relative difference of RMS amplitude of thermal vibration appears at the sheet corners. The microstructure of the graphene sheet has a little effect on the thermal vibrations of lower modes, but exhibits an obvious effect on the thermal vibrations of higher modes. The quantum effect is more important for the thermal vibration of higher modes in the case of smaller sides and lower temperature. The relative difference of maximal RMS amplitude of thermal vibration of a rectangular single-layered graphene sheet decreases monotonically with an increase of temperature. The absolute difference of maximal RMS amplitude of thermal vibration of a rectangular single-layered graphene sheet increases slowly with the rising of Winkler foundation modulus.
Recovery of the Dirac system from the rectangular Weyl matrix function
International Nuclear Information System (INIS)
Fritzsche, B; Kirstein, B; Roitberg, I Ya; Sakhnovich, A L
2012-01-01
Weyl theory for Dirac systems with rectangular matrix potentials is non-classical. The corresponding Weyl functions are rectangular matrix functions. Furthermore, they are non-expansive in the upper semi-plane. Inverse problems are studied for such Weyl functions, and some results are new even for the square Weyl functions. High-energy asymptotics of Weyl functions and Borg–Marchenko-type uniqueness results are derived too. (paper)
The time of simultaneous tunneling of identical particles through the rectangular quantum barrier
International Nuclear Information System (INIS)
Martsenyuk, L.S.; Omelchenko, S.A.
2010-01-01
Work is devoted to studying the influence of exchange processes on a time of simultaneous crossing by identical particles of a rectangular quantum barrier. It is shown, that such processes essentially influence on the parameters of tunneling. The size of addition to time of identical particles tunneling, arising up because of their exchange interaction in a field of a rectangular quantum barrier is first counted.
Design and construction of a mode converter from TE10(rectangular) to TE11(circular)
International Nuclear Information System (INIS)
Tubbing, B.J.D.
1984-08-01
The design and manufacturing of a wavelength mode converter from the TE 10 (rectangular) mode in oversized rectangular to the TE 11 (circular) mode in oversized circular waveguide is described. A differential equation for the cross-sectional shape of the converter was solved numerically. A stainless-steel mandrel was produced on a numerically controlled milling machine. Sixteen converters were produced by means of electroforming on one mandrel. (Auth.)
Experimental investigation on carbon nano tubes coated brass rectangular extended surfaces
International Nuclear Information System (INIS)
Senthilkumar, Rajendran; Prabhu, Sethuramalingam; Cheralathan, Marimuthu
2013-01-01
Finned surface has been extensively used for free convection cooling of internal combustion engines and several electronic kits etc. Here rectangular brass fin was preferred for analysis. Thermocouples were attached all over the surface of the fin in equal distances. The measurement of surface temperature and calculated convective heat transfer rate were reported for several heat input values. The overall system performance can be improved by enhancing heat transfer rate of extended surfaces. Based on the above requirement, brass surface was coated by carbon nano tubes. The temperature and heat transfer characteristics were investigated using Taguchi method for experimental design. Finally the performances of coated and non-coated rectangular brass fins were compared. The average percentage of increase in heat transfer rate was proved around 12% for carbon nanocoated rectangular brass fins. - Graphical abstract: The designed Natural and Forced convection Heat Transfer Test Rig measures the enhanced rate of heat transfer for nano coated rectangular fins than in non-coated fins. Highlights: ► Rectangular brass fins were preferred for convective heat transfer process. ► The rectangular brass fins are coated with multi wall carbon nano tubes in EBPVD process with nanometer thickness. ► Temperature and heat transfer rate were investigated for nanocoated and non-coated fins by using Taguchi method. ► Multi wall carbon nanotubes act as a pin fin to enhance surface area for effective convective heat transfer rate.
Directory of Open Access Journals (Sweden)
Joong-Han Yoon
2013-01-01
Full Text Available A triple-band rectangular ring, open-ended monopole antenna with symmetric L strips for wireless local area network (WLAN/Worldwide Interoperability of Microwave Access (WiMAX applications is proposed. The proposed antenna consists of two symmetric folded arms and L strips. Based on the concept, a prototype of the proposed triple antenna has been designed, fabricated, and tested. The numerical and experimental results demonstrated that the proposed antenna satisfied the −10 dB impedance bandwidth requirement while simultaneously covering the WLAN and WiMAX bands. Furthermore, this paper presented and discussed the 2D radiation patterns and 3D gains according to the results of the experiment. The proposed antenna’s peak gain varied between 2.17 and 4.93 dBi, and its average gain varied between −2.97 and −0.53 dBi.
Directory of Open Access Journals (Sweden)
Bo Yan
2013-01-01
Full Text Available A novel ultrawideband (UWB antenna which has a triple-band notch function is presented. The proposed antenna can block interfering signals from C-band satellite communication systems, IEEE802.11a, and HIPERLAN/2 WLAN systems for example. The antenna is excited by using novel common direction rectangular complementary split-ring resonators (CSRR fabricated on radiating patch of the dielectric substrate with coplanar waveguide (CPW feed strip line. The voltage standing wave ratio (VSWR of the proposed antenna is less than 2.0 in the frequency band from 2.8 to 12 GHz, while showing a very sharp band-rejection performance at 3.9 GHz, 5.2 GHz, and 5.9 GHz. The measurement results show that the proposed antenna provides good omnidirectional field pattern over its whole frequency band excluding the rejected band, which is suitable for UWB applications.
Wavenumber locking and pattern formation in spatially forced systems
International Nuclear Information System (INIS)
Manor, Rotem; Meron, Ehud; Hagberg, Aric
2009-01-01
We study wavenumber locking and pattern formation resulting from weak spatially periodic one-dimensional forcing of two-dimensional systems. We consider systems that produce stationary or traveling stripe patterns when unforced and apply forcing aligned with the stripes. Forcing at close to twice the pattern wavenumber selects, stabilizes, or creates resonant stripes locked at half the forcing wavenumber. If the mismatch between the forcing and pattern wavenumber is high we find that the pattern still locks but develops a wave vector component perpendicular to the forcing direction and forms rectangular and oblique patterns. When the unforced system supports traveling waves, resonant rectangular patterns remain stationary but oblique patterns travel in a direction orthogonal to the traveling waves.
Yu, C.
1983-01-01
Flexible hollow metallic rectangular pipes and infrared fibers are proposed as alternate media for collection, guidance and manipulation of mid-infrared tunable diode laser (TDL) radiation. Certain features of such media are found to be useful for control of TDL far field patterns, polarization and possibly intensity fluctuations. Such improvement in dimension compatibility may eventually lead to laser heterodyne spectroscopy (LHS) and optical communication system compaction and integration. Infrared optical fiber and the compound parabolic coupling of light into a hollow pipe waveguide are discussed as well as the design of the waveguide.
Regionalization of the Modified Bartlett-Lewis Rectangular Pulse Stochastic Rainfall Model
Directory of Open Access Journals (Sweden)
Dongkyun Kim
2013-01-01
Full Text Available Parameters of the Modified Bartlett-Lewis Rectangular Pulse (MBLRP stochastic rainfall simulation model were regionalized across the contiguous United States. Three thousand four hundred forty-four National Climate Data Center (NCDC rain gauges were used to obtain spatial and seasonal patterns of the model parameters. The MBLRP model was calibrated to minimize the discrepancy between the precipitation depth statistics between the observed and MBLRP-generated precipitation time series. These statistics included the mean, variance, probability of zero rainfall and autocorrelation at 1-, 3-, 12- and 24-hour accumulation intervals. The Ordinary Kriging interpolation technique was used to generate maps of the six MBLRP model parameters for each of the 12 months of the year. All parameters had clear to discernible regional tendencies; except for one related to rain cell duration distribution. Parameter seasonality was not obvious and it was more apparent in some locations than in others, depending on the seasonality of the rainfall statistics. Cross-validation was used to assess the validity of the parameter maps. The results indicate that the suggested maps reproduce well the observed rainfall statistics for different accumulation intervals, except for the lag-1 autocorrelation coefficient. The boundaries of the expected residual, with 95% confidence, between the observed rainfall statistics and the simulated rainfall statistics based on the map parameters were approximately ±0.064 mm hr-1, ±1.63 mm2 hr-2, ±0.16, and ±0.030 for the mean, variance, lag-1 autocorrelation and probability of zero rainfall at hourly accumulation levels, respectively. The estimated parameter values were also used to estimate the storm and rain cell characteristics.
Rotated grating coupled surface plasmon resonance on wavelength-scaled shallow rectangular gratings
Szalai, A.; Szekeres, G.; Balázs, J.; Somogyi, A.; Csete, Maria
2013-09-01
Theoretical investigation of rotated grating coupling phenomenon was performed on a multilayer comprising 416-nmperiodic shallow rectangular polymer grating on bimetal film made of gold and silver layers. During the multilayer illumination by 532 nm wavelength p-polarized light the polar and azimuthal angles were varied. In presence of 0-35 nm, 0-50 nm and 15-50 nm thick polymer-layers at the valleys and hills splitting was observed on the dual-angle dependent reflectance in two regions: (i) close to 0° azimuthal angle corresponding to incidence plane parallel to the periodic pattern (P-orientation); and (ii) around ~33.5°/29°/30° azimuthal angle (C-orientation), in agreement with our previous experimental studies. The near-field study revealed that in P-orientation the E-field is enhanced at the glass side with p/2 periodicity at the first minimum appearing at 49°/50°/52° polar angles, and comprises maxima below both the valleys and hills; while E-field enhancement is observable both at the glass and polymer side with p-periodicity at the second minimum developing at 55°/63/64° tilting, comprising maxima intermittently below the valleys or above the hills. In Corientation coupled plasmonic modes are observable, involving modes propagating along the valleys at the secondary maxima appearing at ~35°/32°/32° azimuthal and ~49°/51°/56° polar angles, while modes confined along the polymer hills are observable at the primary minima, which are coupled most strongly at the ~31.5°/25°/28° azimuthal and ~55°/63°/66° polar angles. The secondary peak observable in C-orientation is proposed for biosensing applications, since the supported modes are confined along the valleys, where biomolecules prefer to attach.
Zhang, Ruobing; Liang, Dapeng; Zheng, Nanchen; Xiao, Jianfu; Mo, Mengbin; Li, Jing
2013-03-01
Pulsed electric field (PEF) is a novel non-thermal food processing technology that involves the electric discharge of high voltage short pulses through the food product. In PEF study, rectangular pulses are most commonly used for inactivating microorganisms. However, little information is available on the inactivation effect of rising time of rectangular pulse. In this paper, inactivation effects, electric field strength, treatment time and conductivity on staphylococcus aureus inactivation were investigated when the pulse rising time is reduced from 2.5 μs to 200 ns. Experimental results showed that inactivation effect of PEF increased with electric field strength, solution conductivity and treatment time. Rising time of the rectangular pulse had a significant effect on the inactivation of staphylococcus aureus. Rectangular pulses with a rising time of 200 ns had a better inactivation effect than that with 2 μs. In addition, temperature increase of the solution treated by pulses with 200 ns rising time was lower than that with 2 μs. In order to obtain a given inactivation effect, treatment time required for the rectangular pulse with 200 ns rise time was shorter than that with 2 μs.
Optimal design for rectangular isolated footings using the real soil pressure
Directory of Open Access Journals (Sweden)
Arnulfo Luévanos Rojas
2017-05-01
Full Text Available The standard design method (classical method for reinforced concrete rectangular footings is: First, a dimension is proposed and should comply with the allowable stresses; subsequently, the effective depth is obtained from the maximum moment and is checked against the bending shear and the punching shear until, it complies with these conditions and, then, steel reinforcement is obtained, but it is not guarantee that the minimum cost will be obtained. This paper shows an optimal design for reinforced concrete rectangular footings using the new model. A numerical experimentation is presented to show the model capability to estimate the minimum cost design of the materials used for a rectangular footing that supports an axial load and moments in two directions in accordance to the building code requirements for structural concrete and commentary (ACI 318-13. Also, a comparison is made between the optimal design and current design for rectangular footings. The solutions show that the optimal design is more economical and more precise with respect to the current design, because standard design is done by trial and error. Then, the optimal design should be used to obtain the minimum cost design for reinforced concrete rectangular footings.
International Nuclear Information System (INIS)
Zhang, Ruobing; Liang, Dapeng; Xiao, Jianfu; Mo, Mengbin; Li, Jing; Zheng, Nanchen
2013-01-01
Pulsed electric field (PEF) is a novel non-thermal food processing technology that involves the electric discharge of high voltage short pulses through the food product. In PEF study, rectangular pulses are most commonly used for inactivating microorganisms. However, little information is available on the inactivation effect of rising time of rectangular pulse. In this paper, inactivation effects, electric field strength, treatment time and conductivity on staphylococcus aureus inactivation were investigated when the pulse rising time is reduced from 2.5 μs to 200 ns. Experimental results showed that inactivation effect of PEF increased with electric field strength, solution conductivity and treatment time. Rising time of the rectangular pulse had a significant effect on the inactivation of staphylococcus aureus. Rectangular pulses with a rising time of 200 ns had a better inactivation effect than that with 2 μs. In addition, temperature increase of the solution treated by pulses with 200 ns rising time was lower than that with 2 μs. In order to obtain a given inactivation effect, treatment time required for the rectangular pulse with 200 ns rise time was shorter than that with 2 μs.
Analysis of the rectangular resonator with butterfly MMI coupler using SOI
Kim, Sun-Ho; Park, Jun-Hee; Kim, Eudum; Jeon, Su-Jin; Kim, Ji-Hoon; Choi, Young-Wan
2018-02-01
We propose a rectangular resonator sensor structure with butterfly MMI coupler using SOI. It consists of the rectangular resonator, total internal reflection (TIR) mirror, and the butterfly MMI coupler. The rectangular resonator is expected to be used as bio and chemical sensors because of the advantages of using MMI coupler and the absence of bending loss unlike ring resonators. The butterfly MMI coupler can miniaturize the device compared to conventional MMI by using a linear butterfly shape instead of a square in the MMI part. The width, height, and slab height of the rib type waveguide are designed to be 1.5 μm, 1.5 μm, and 0.9 μm, respectively. This structure is designed as a single mode. When designing a TIR mirror, we considered the Goos-Hänchen shift and critical angle. We designed 3:1 MMI coupler because rectangular resonator has no bending loss. The width of MMI is designed to be 4.5 μm and we optimize the length of the butterfly MMI coupler using finite-difference time-domain (FDTD) method for higher Q-factor. It has the equal performance with conventional MMI even though the length is reduced by 1/3. As a result of the simulation, Qfactor of rectangular resonator can be obtained as 7381.
International Nuclear Information System (INIS)
Wang Junfeng; Huang Yanping; Wang Yanlin; Song Mingliang
2012-01-01
Highlights: ► Flow regimes were visually investigated in a heated narrow rectangular channel. ► Bubbly, churn, and annular flow were observed. Slug flow was never observed. ► Flow regime transition boundary could be predicted by existing criteria. ► Churn zone in present flow regime maps were poorly predicted by existing criteria. - Abstract: Flow regimes are very important in understanding two-phase flow resistance and heat transfer characteristics. In present work, two-phase flow regimes for steam–water flows in a single-side heated narrow rectangular channel, having a width of 40 mm and a gap of 3 mm, were visually studied at relatively low pressure and low mass flux condition. The flow regimes observed in this experiment could be classified into bubbly, churn and annular flow. Slug flow was never observed at any of the conditions in our experiment. Flow regime maps at the pressure of 0.7 MPa and 1.0 MPa were developed, and then the pressure effect on flow regime transition was analyzed. Based on the experimental results, the comparisons with some existing flow regime maps and transition criteria were conducted. The comparison results show that the bubbly transition boundary and annular formation boundary of heated steam–water flow were consistent with that of adiabatic air–water flow. However, the intermediate flow pattern between bubbly and annular flow was different. Hibiki and Mishima criteria could predict the bubbly transition boundary and annular formation boundary satisfactorily, but it poorly predicted churn zone in present experimental data.
PERFORMANCE ANALYSIS OF RECTANGULAR MPA USING DIFFERENT SUBSTRATE MATERIALS FOR WLAN APPLICATION
Directory of Open Access Journals (Sweden)
E Aravindraj
2017-03-01
Full Text Available In this paper, a rectangular microstrip patch antenna (MPA is designed using different substrate materials for analyzing the performance of the MPA. Alumina (Al2O3, Bakelite, Beryllium oxide (BeO, Gallium Arsenide (GaAs, RT-Duroid and Flame Retardant 4 (FR-4 are the six different substrate used in the design. The size of the rectangular microstrip patch antenna varies according to the dielectric constant of substrate materials used. The operating frequency taken for this analysis is 5.8 GHz. The proposed design provides the study on the performance of rectangular microstrip patch antenna for different substrate materials using the same frequency. This study conveys that which substrate material provides better performance. Moreover, this comparative study conveys that which substrate material provides better performance. The simulation parameters are investigated using HFSS.
Palisoc, Arthur L.; Lee, Chin C.
1988-12-01
Using the method of images and the analytical temperature solution to the multilayer infinite plate structure, the thermal profile over finite rectangular multilayer integrated circuit devices can be calculated exactly. The advantage of using the image method lies in the enhanced capability of arriving at an analytical solution for structures where analytical solutions do not apparently exist, e.g., circular or arbitrarily oriented rectangular sources over multilayered rectangular structures. The new approach results in large savings in computer CPU time especially for small sources over large substrates. The method also finds very important applications to integrated circuit devices with heat dissipating elements close to the edge boundaries. Results from two examples indicate that the edge boundaries of a device may also be utilized to remove heat from it. This additional heat removing capability should have important applications in high power devices.
One-dimensional nonlinear theory for rectangular helix traveling-wave tube
Energy Technology Data Exchange (ETDEWEB)
Fu, Chengfang, E-mail: fchffchf@126.com; Zhao, Bo; Yang, Yudong; Ju, Yongfeng [Faculty of Electronic Information Engineering, Huaiyin Institute of Technology, Huai' an 223003 (China); Wei, Yanyu [School of Physical Electronics, University of Electronic and Technology of China, Chengdu 610054 (China)
2016-08-15
A 1-D nonlinear theory of a rectangular helix traveling-wave tube (TWT) interacting with a ribbon beam is presented in this paper. The RF field is modeled by a transmission line equivalent circuit, the ribbon beam is divided into a sequence of thin rectangular electron discs with the same cross section as the beam, and the charges are assumed to be uniformly distributed over these discs. Then a method of computing the space-charge field by solving Green's Function in the Cartesian Coordinate-system is fully described. Nonlinear partial differential equations for field amplitudes and Lorentz force equations for particles are solved numerically using the fourth-order Runge-Kutta technique. The tube's gain, output power, and efficiency of the above TWT are computed. The results show that increasing the cross section of the ribbon beam will improve a rectangular helix TWT's efficiency and reduce the saturated length.
DNB Mechanistic model assessment based on experimental data in narrow rectangular channel
International Nuclear Information System (INIS)
Zhou Lei; Yan Xiao; Huang Yanping; Xiao Zejun; Huang Shanfang
2011-01-01
The departure from nuclear boiling (DNB) is important concerning about the safety of a PWR. Lacking assessment by experimental data points, it's doubtful whether the existing models can be used in narrow rectangular channels or not. Based on experimental data points in narrow rectangular channels, two kinds of classical DNB models, which include liquid sublayer dryout model (LSDM) and bubble crowding model (BCM), were assessed. The results show that the BCM has much wider application range than the LSDM. Several thermal parameters show systematical influences on the calculated results by the models. The performances of all the models deteriorate as the void fraction increases. The reason may be attributed to the geometrical differences between a circular tube and narrow rectangular channel. (authors)
Review of Critical Heat Flux Correlations for Upward Flow in a Vertical Thin Rectangular Channel
Energy Technology Data Exchange (ETDEWEB)
Choi, Gil Sik; Chang, Soon Heung [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)
2014-05-15
From the view point of safety, this type of fuel has higher resistance to earthquake and external impact. The cross section of coolant flow channel in the reactor core composed with the plate fuel is a thin rectangular shape. Thermal-hydraulic characteristics of this thin rectangular channel are different with those of general circular rod fuel bundle flow channel. Accordingly it could be thought that the CHF correlation in a thin rectangular channel is different with that in a circular channel, for which a large number of researches on CHF prediction have been carried out. The objective of this paper is to review previous researches on CHF in a thin rectangular channel, summarize the important conclusion and propose the new simple CHF correlation, which is based on the data set under high pressure and high flow rate condition. The researches on CHF in rectangular channel have been partially carried out according to the pressure, heated surface number, heated surface wettability effect, flow driving force and flow direction conditions. From the literature researches on CHF for upward flow in a vertical thin rectangular channel, some CHF prediction methods were reviewed and compared. There is no universal correlation which can predict CHF at all conditions, but generally, Katto empirical correlation is known to be useful at high pressure and high flow rate. The new simple correlation was developed from the restricted data set, the CHF prediction capacity of which is better than that of Katto. Even though the prediction consistency of the new simple correlation is lower, MAE and RMS error decreased quite. For the more development of the new simple CHF correlation, the more advanced regression analysis method and theoretical analysis should be studied in future.
Review of Critical Heat Flux Correlations for Upward Flow in a Vertical Thin Rectangular Channel
International Nuclear Information System (INIS)
Choi, Gil Sik; Chang, Soon Heung
2014-01-01
From the view point of safety, this type of fuel has higher resistance to earthquake and external impact. The cross section of coolant flow channel in the reactor core composed with the plate fuel is a thin rectangular shape. Thermal-hydraulic characteristics of this thin rectangular channel are different with those of general circular rod fuel bundle flow channel. Accordingly it could be thought that the CHF correlation in a thin rectangular channel is different with that in a circular channel, for which a large number of researches on CHF prediction have been carried out. The objective of this paper is to review previous researches on CHF in a thin rectangular channel, summarize the important conclusion and propose the new simple CHF correlation, which is based on the data set under high pressure and high flow rate condition. The researches on CHF in rectangular channel have been partially carried out according to the pressure, heated surface number, heated surface wettability effect, flow driving force and flow direction conditions. From the literature researches on CHF for upward flow in a vertical thin rectangular channel, some CHF prediction methods were reviewed and compared. There is no universal correlation which can predict CHF at all conditions, but generally, Katto empirical correlation is known to be useful at high pressure and high flow rate. The new simple correlation was developed from the restricted data set, the CHF prediction capacity of which is better than that of Katto. Even though the prediction consistency of the new simple correlation is lower, MAE and RMS error decreased quite. For the more development of the new simple CHF correlation, the more advanced regression analysis method and theoretical analysis should be studied in future
Rarefied gas flow in a rectangular enclosure induced by non-isothermal walls
Energy Technology Data Exchange (ETDEWEB)
Vargas, Manuel; Tatsios, Giorgos; Valougeorgis, Dimitris, E-mail: diva@mie.uth.gr [Department of Mechanical Engineering, University of Thessaly, 38334 Volos (Greece); Stefanov, Stefan [Institute of Mechanics, Bulgarian Academy of Sciences, Sofia (Bulgaria)
2014-05-15
The flow of a rarefied gas in a rectangular enclosure due to the non-isothermal walls with no synergetic contributions from external force fields is investigated. The top and bottom walls are maintained at constant but different temperatures and along the lateral walls a linear temperature profile is assumed. Modeling is based on the direct numerical solution of the Shakhov kinetic equation and the Direct Simulation Monte Carlo (DSMC) method. Solving the problem both deterministically and stochastically allows a systematic comparison and verification of the results as well as the exploitation of the numerical advantages of each approach in the investigation of the involved flow and heat transfer phenomena. The thermally induced flow is simulated in terms of three dimensionless parameters characterizing the problem, namely, the reference Knudsen number, the temperature ratio of the bottom over the top plates, and the enclosure aspect ratio. Their effect on the flow configuration and bulk quantities is thoroughly examined. Along the side walls, the gas flows at small Knudsen numbers from cold-to-hot, while as the Knudsen number is increased the gas flows from hot-to-cold and the thermally induced flow configuration becomes more complex. These flow patterns with the hot-to-cold flow to be extended to the whole length of the non-isothermal side walls may exist even at small temperature differences and then, they are enhanced as the temperature difference between the top and bottom plates is increased. The cavity aspect ratio also influences this flow configuration and the hot-to-cold flow is becoming more dominant as the depth compared to the width of the cavity is increased. To further analyze the flow patterns a novel solution decomposition into ballistic and collision parts is introduced. This is achieved by accordingly modifying the indexing process of the typical DSMC algorithm. The contribution of each part of the solution is separately examined and a physical
Directory of Open Access Journals (Sweden)
Wenbo Duan
2017-12-01
Full Text Available Ultrasonic guided waves are widely used to inspect and monitor the structural integrity of plates and plate-like structures, such as ship hulls and large storage-tank floors. Recently, ultrasonic guided waves have also been used to remove ice and fouling from ship hulls, wind-turbine blades and aeroplane wings. In these applications, the strength of the sound source must be high for scanning a large area, or to break the bond between ice, fouling and plate substrate. More than one transducer may be used to achieve maximum sound power output. However, multiple sources can interact with each other, and form a sound field in the structure with local constructive and destructive regions. Destructive regions are weak regions and shall be avoided. When multiple transducers are used it is important that they are arranged in a particular way so that the desired wave modes can be excited to cover the whole structure. The objective of this paper is to provide a theoretical basis for generating particular wave mode patterns in finite-width rectangular plates whose length is assumed to be infinitely long with respect to its width and thickness. The wave modes have displacements in both width and thickness directions, and are thus different from the classical Lamb-type wave modes. A two-dimensional semi-analytical finite element (SAFE method was used to study dispersion characteristics and mode shapes in the plate up to ultrasonic frequencies. The modal analysis provided information on the generation of modes suitable for a particular application. The number of point sources and direction of loading for the excitation of a few representative modes was investigated. Based on the SAFE analysis, a standard finite element modelling package, Abaqus, was used to excite the designed modes in a three-dimensional plate. The generated wave patterns in Abaqus were then compared with mode shapes predicted in the SAFE model. Good agreement was observed between the
International Nuclear Information System (INIS)
Sugano, Y.
1980-01-01
The transient thermal stresses in an orthotropic finite rectangular plate due to arbitrary surface heat-generations on two edges are studied by means of the Airy stress function. The purposes of this paper are to present a method of determing the transient thermal stresses in an orthographic rectangular plate with four edges of distinct thermal boundary condition of the third kind which exactly satisfy the traction-free conditions of shear stress over all boundaries including four corners of the plate, and to consider the effects of the anisotropies of material properties and the convective heat transfer on the upper and lower surfaces on the thermal stress distribution. (orig.)
A study on liquid lithium flow in rectangular duck perpendicular to a intense magnetic field
International Nuclear Information System (INIS)
Shen Xiuzhong; Chen Ke; Liu Yang; Zhang Qinshun
2001-01-01
A research on high-speed liquid-metal lithium flow through a non-expanding rectangular duck under uniform intense magnetic field is presented. A equations set with Poisson equation and Helmholtz equation, which control the electrical field and flow field respectively, has been deduced by analysis and PHsolver, a program to solve the equations set, has also been finished. The current density distribution and flow field in the non-expanding rectangular channel with intense magnetic field have been obtained from PHsolver by applying the wall-function in the boundary wall. The velocity profile in the duck appears M-shaped
Cao, Nan; Cao, Fengmei; Lin, Yabin; Bai, Tingzhu; Song, Shengyu
2015-04-01
For a new kind of retina-like senor camera and a traditional rectangular sensor camera, dual cameras acquisition and display system need to be built. We introduce the principle and the development of retina-like senor. Image coordinates transformation and interpolation based on sub-pixel interpolation need to be realized for our retina-like sensor's special pixels distribution. The hardware platform is composed of retina-like senor camera, rectangular sensor camera, image grabber and PC. Combined the MIL and OpenCV library, the software program is composed in VC++ on VS 2010. Experience results show that the system can realizes two cameras' acquisition and display.
Directory of Open Access Journals (Sweden)
K. Rahmani
2018-05-01
Full Text Available In this paper we present a pipeline for high quality semantic segmentation of building facades using Structured Random Forest (SRF, Region Proposal Network (RPN based on a Convolutional Neural Network (CNN as well as rectangular fitting optimization. Our main contribution is that we employ features created by the RPN as channels in the SRF.We empirically show that this is very effective especially for doors and windows. Our pipeline is evaluated on two datasets where we outperform current state-of-the-art methods. Additionally, we quantify the contribution of the RPN and the rectangular fitting optimization on the accuracy of the result.
International Nuclear Information System (INIS)
Martsenyuk, L.S.
2010-01-01
Research of influence of exchange interaction of identical particles for the time of their simultaneous tunneling through a rectangular quantum barrier is lead. The account of identity leads to necessity of symmetrisation of wave function owing to what in the formula describing interaction of two particles, arises an additional element. In result the parameters of tunneling, including time of tunneling change. Time of tunneling is calculated from the formula received in work from the size of exchange interaction of two particles simultaneously crossing a rectangular quantum barrier.
Lyashko, A. D.
2017-11-01
A new analytical presentation of the solution for steady-state oscillations of orthotopic rectangular prism is found. The corresponding infinite system of linear algebraic equations has been deduced by the superposition method. A countable set of precise eigenfrequencies and elementary eigenforms is found. The identities are found which make it possible to improve the convergence of all the infinite series in the solution of the problem. All the infinite series in presentation of solution are analytically summed up. Numerical calculations of stresses in the rectangular orthotropic prism with a uniform along the border and harmonic in time load on two opposite faces have been performed.
Natural Frequency of F.G. Rectangular Plate by Shear Deformation Theory
International Nuclear Information System (INIS)
Shahrjerdi, Ali; Sapuan, S M; Shahzamanian, M M; Mustapha, F; Zahari, R; Bayat, M
2011-01-01
Natural frequency of functionally graded (F.G.) rectangular plate is carried out by using second-order shear deformation theory (SSDT). The material properties of functionally graded rectangular plates, except the Poisson's ratio, are assumed to vary continuously through the thickness of the plate in accordance with the exponential law distribution. The equations of motion are obtained by energy method. Numerical results for functionally graded plates are given in dimensionless graphical forms and the effects of material properties on natural frequency are determined.
Haar-like Rectangular Features for Biometric Recognition
DEFF Research Database (Denmark)
Nasrollahi, Kamal; Moeslund, Thomas B.; Rashidi, Maryam
2013-01-01
Developing a reliable, fast, and robust biometric recognition system is still a challenging task. This is because the inputs to these systems can be noisy, occluded, poorly illuminated, rotated, and of very low-resolutions. This paper proposes a probabilistic classifier using Haar-like features......, which mostly have been used for detection, for biometric recognition. The proposed system has been tested for three different biometrics: ear, iris, and hand vein patterns and it is shown that it is robust against most of the mentioned degradations and it outperforms state-of-the-art systems...
Inspiratory flow pattern in humans.
Lafortuna, C L; Minetti, A E; Mognoni, P
1984-10-01
The theoretical estimation of the mechanical work of breathing during inspiration at rest is based on the common assumption that the inspiratory airflow wave is a sine function of time. Different analytical studies have pointed out that from an energetic point of view a rectangular wave is more economical than a sine wave. Visual inspection of inspiratory flow waves recorded during exercise in humans and various animals suggests that a trend toward a rectangular flow wave may be a possible systematic response of the respiratory system. To test this hypothesis, the harmonic content of inspiratory flow waves that were recorded in six healthy subjects at rest, during exercise hyperventilation, and during a maximum voluntary ventilation (MVV) maneuver were evaluated by a Fourier analysis, and the results were compared with those obtained on sinusoidal and rectangular models. The dynamic work inherent in the experimental waves and in the sine-wave model was practically the same at rest; during exercise hyperventilation and MVV, the experimental wave was approximately 16-20% more economical than the sinusoidal one. It was concluded that even though at rest the sinusoidal model is a reasonably good approximation of inspiratory flow, during exercise and MVV, a physiological controller is probably operating in humans that can select a more economical inspiratory pattern. Other peculiarities of airflow wave during hyperventilation and some optimization criteria are also discussed.
2011-10-18
... Rectangular Carbon Steel Tubing From Taiwan: Final Results of the Expedited Sunset Review of the Antidumping... the antidumping duty order on light-walled welded rectangular carbon steel tubing from Taiwan pursuant... steel tubing from Taiwan pursuant to section 751(c) of the Act. See Initiation of Five-Year (``Sunset...
2012-02-02
... Rectangular Carbon Steel Tubing From Taiwan: Continuation of Antidumping Duty Order AGENCY: Import... revocation of the antidumping duty order on light-walled welded rectangular carbon steel tubing from Taiwan would likely lead to a continuation or recurrence of dumping and material injury to an industry in the...
Optical implementation of (3, 3, 2) regular rectangular CC-Banyan optical network
Yang, Junbo; Su, Xianyu
2007-07-01
CC-Banyan network plays an important role in the optical interconnection network. Based on previous reports of (2, 2, 3) the CC-Banyan network, another rectangular-Banyan network, i.e. (3, 3, 2) rectangular CC-Banyan network, has been discussed. First, according to its construction principle, the topological graph and the routing rule of (3, 3, 2) rectangular CC-Banyan network have been proposed. Then, the optically experimental setup of (3, 3, 2) rectangular CC-Banyan network has been designed and achieved. Each stage of node switch consists of phase spatial light modulator (PSLM) and polarizing beam-splitter (PBS), and fiber has been used to perform connection between adjacent stages. PBS features that s-component (perpendicular to the incident plane) of the incident light beam is reflected, and p-component (parallel to the incident plane) passes through it. According to switching logic, under the control of external electrical signals, PSLM functions to control routing paths of the signal beams, i.e. the polarization of each optical signal is rotated or not rotated 90° by a programmable PSLM. Finally, the discussion and analysis show that the experimental setup designed here can realize many functions such as optical signal switch and permutation. It has advantages of large number of input/output-ports, compact in structure, and low energy loss. Hence, the experimental setup can be used in optical communication and optical information processing.
The Effects of a Rectangular Rapid-Flashing Beacon on Vehicle Speed
VanWagner, Michelle; Van Houten, Ron; Betts, Brian
2011-01-01
In 2008, nearly 31% of vehicle fatalities were related to failure to adhere to safe vehicle speeds (National Highway Traffic Safety Administration [NHTSA], 2009). The current study evaluated the effect of a rectangular rapid-flashing beacon (RRFB) triggered by excessive speed on vehicle speed using a combined alternating treatments and reversal…
Sman, van der R.G.M.
2006-01-01
In this paper we present lattice Boltzmann (LB) schemes for convection diffusion coupled to fluid flow on two-dimensional rectangular lattices. Via inverse Chapman-Enskog analysis of LB schemes including source terms, we show that for consistency with physics it is required that the moments of the
Scattering of E Polarized Plane Wave by Rectangular Cavity With Finite Flanges
Vinogradova, Elena D.
2017-11-01
The rigorous Method of Regularization is implemented for accurate analysis of wave scattering by rectangular cavity with finite flanges. The solution is free from limitations on problem parameters. The calculation of the induced surface current, bistatic radar cross section (RCS) and frequency dependence of monostatic RCS are performed with controlled accuracy in a wide frequency band.
Rectangular optical filter based on high-order silicon microring resonators
Bao, Jia-qi; Yu, Kan; Wang, Li-jun; Yin, Juan-juan
2017-07-01
The rectangular optical filter is one of the most important optical switching components in the dense wavelength division multiplexing (DWDM) fiber-optic communication system and the intelligent optical network. The integrated highorder silicon microring resonator (MRR) is one of the best candidates to achieve rectangular filtering spectrum response. In general, the spectrum response rectangular degree of the single MRR is very low, so it cannot be used in the DWDM system. Using the high-order MRRs, the bandwidth of flat-top pass band, the out-of-band rejection degree and the roll-off coefficient of the edge will be improved obviously. In this paper, a rectangular optical filter based on highorder MRRs with uniform couplers is presented and demonstrated. Using 15 coupled race-track MRRs with 10 μm in radius, the 3 dB flat-top pass band of 2 nm, the out-of-band rejection ratio of 30 dB and the rising and falling edges of 48 dB/nm can be realized successfully.
Rectangular optical filter based on high-order silicon microring resonators
Institute of Scientific and Technical Information of China (English)
BAO Jia-qi; YU Kan; WANG Li-jun; YIN Juan-juan
2017-01-01
The rectangular optical filter is one of the most important optical switching components in the dense wavelength division multiplexing (DWDM) fiber-optic communication system and the intelligent optical network.The integrated highorder silicon microring resonator (MRR) is one of the best candidates to achieve rectangular filtering spectrum response.In general,the spectrum response rectangular degree of the single MRR is very low,so it cannot be used in the DWDM system.Using the high-order MRRs,the bandwidth of flat-top pass band,the out-of-band rejection degree and the roll-off coefficient of the edge will be improved obviously.In this paper,a rectangular optical filter based on highorder MRRs with uniform couplers is presented and demonstrated.Using 15 coupled race-track MRRs with 10 μm in radius,the 3 dB flat-top pass band of 2 nm,the out-of-band rejection ratio of 30 dB and the rising and falling edges of 48 dB/nm can be realized successfully.
Analytical study of a reversed-field pinch with rectangular cross section
International Nuclear Information System (INIS)
Zhang Peng
1990-01-01
An analyic solution of the force-free equation for a toroidal configuration of rectangular cross section is presented. It is shown that the critical value of contraction ratio for the appearance of a reversed field as well as of the ohmic current increases as the elongation of the cross section increases
Hydrodynamics of slug flow in a vertical narrow rectangular channel under laminar flow condition
International Nuclear Information System (INIS)
Wang, Yang; Yan, Changqi; Cao, Xiaxin; Sun, Licheng; Yan, Chaoxing; Tian, Qiwei
2014-01-01
Highlights: • Slug flow hydrodynamics in a vertical narrow rectangular duct were investigated. • The velocity of trailing Taylor bubble undisturbed by the leading one was measured. • Correlation of Taylor bubble velocity with liquid slug length ahead it was proposed. • Evolution of length distributions of Taylor bubble and liquid slug was measured. • The model of predicted length distributions was applied to the rectangular channel. - Abstract: The hydrodynamics of gas–liquid two-phase slug flow in a vertical narrow rectangular channel with the cross section of 2.2 mm × 43 mm is investigated using a high speed video camera system. Simultaneous measurements of velocity and duration of Taylor bubble and liquid slug made it possible to determine the length distributions of the liquid slug and Taylor bubble. Taylor bubble velocity is dependent on the length of the liquid slug ahead, and an empirical correlation is proposed based on the experimental data. The length distributions of Taylor bubbles and liquid slugs are positively skewed (log-normal distribution) at all measuring positions for all flow conditions. A modified model based on that for circular tubes is adapted to predict the length distributions in the present narrow rectangular channel. In general, the experimental data is well predicted by the modified model
Numerical analysis and optimization of 3D magnetohydrodynamic flows in rectangular U-bend
Energy Technology Data Exchange (ETDEWEB)
He, Qingyun, E-mail: hqingyun@mail.ustc.edu.cn; Feng, Jingchao; Chen, Hongli, E-mail: hlchen1@ustc.edu.cn
2016-11-01
Highlights: • MHD flows in rectangular U bends have been investigated under specific magnetic field. • U bends analyzed with different aspect ratio, distance of U bends and the wall conductance ratio. • Pressure optimization of rectangular U bends at corner region. • Studying different inclination of magnetic field cases according to original MHD flows. - Abstract: Liquid metal flow in rectangular bends is a common phenomenon of fusion liquid metal blanket operation, in which the velocity distributions and magnetohydrodynamic (MHD) pressure drop are considered as critical issues. Previous studies mainly aimed at specific fixed geometry for bend flows in LM blanket. The present investigation focuses on numerical analysis of MHD flow in 3D rectangular bends at laminar conditions, which is aimed to reduce MHD pressure drop caused by electromagnetic coupling in conductive flow, especially in bend corner region. The used code has been developed by University of Science and Technology of China (USTC) and validated by recommended benchmark cases such as Shercliff, ALEX experiments and KIT experiment cases, etc. In order to search the optimal duct bending, certain parameters such as different aspect ratio of the duct corner area cross-section, distance of import and export from the elbow and wall conductance ratio have been considered to investigate the pressure drop of MHD flow. Moreover, the effects of different magnetic field direction relative to flow distribution between bends have also been analyzed.
Modeling and Chaotic Dynamics of the Laminated Composite Piezoelectric Rectangular Plate
Directory of Open Access Journals (Sweden)
Minghui Yao
2014-01-01
Full Text Available This paper investigates the multipulse heteroclinic bifurcations and chaotic dynamics of a laminated composite piezoelectric rectangular plate by using an extended Melnikov method in the resonant case. According to the von Karman type equations, Reddy’s third-order shear deformation plate theory, and Hamilton’s principle, the equations of motion are derived for the laminated composite piezoelectric rectangular plate with combined parametric excitations and transverse excitation. The method of multiple scales and Galerkin’s approach are applied to the partial differential governing equation. Then, the four-dimensional averaged equation is obtained for the case of 1 : 3 internal resonance and primary parametric resonance. The extended Melnikov method is used to study the Shilnikov type multipulse heteroclinic bifurcations and chaotic dynamics of the laminated composite piezoelectric rectangular plate. The necessary conditions of the existence for the Shilnikov type multipulse chaotic dynamics are analytically obtained. From the investigation, the geometric structure of the multipulse orbits is described in the four-dimensional phase space. Numerical simulations show that the Shilnikov type multipulse chaotic motions can occur. To sum up, both theoretical and numerical studies suggest that chaos for the Smale horseshoe sense in motion exists for the laminated composite piezoelectric rectangular plate.
Comparison of rectangular and dual-planar positron emission mammography scanners
International Nuclear Information System (INIS)
Qi, Jinyi; Kuo, Chaincy; Huesman, Ronald H.; Klein, Gregory J.; Moses, William W.; Reutter, Bryan W.
2002-01-01
Breast imaging using dedicated positron emission tomography (PEM) has gained much interest in the medical imaging field. In this paper, we compare the performance between a rectangular geometry and a parallel dual-planar geometry. Both geometries are studied with depth of interaction (DOI) detectors and non- DOI detectors. We compare the Fisher-information matrix, lesion detection, and quantitation of the four systems. The lesion detectability is measured by the signal-to-noise ratio (SNR) of a prewhitening numerical observer for detecting a known hot spot on a uniform background. Results show that the rectangular system with DOI has the highest SNR for the detection task and the lowest bias at any given noise level for the quantitation task. They also show that for small simulated lesions the parallel dual-planar system with DOI detectors outperforms the rectangular system with non-DOI detectors, while the rectangular system with non-DOI detectors can outperform the parallel dual-planar system with DOI detectors for large simulated lesions
Edge Effects in a Composite Weakly Reinforced with Fibers of Rectangular Cross Section
Boichuk, V. Yu.
2001-05-01
This paper deal with the edge effect in a composite weakly reinforced with fibers of rectangular cross section and subjected to biaxial uniform loading. The edge effects due to the difference between Poisson's ratios of the composite components are studied. Numerical results are presented
From the rectangular to the quincunx Gabor lattice via fractional Fourier transformation
Bastiaans, M.J.; Leest, van A.J.
1998-01-01
Transformations of Gabor lattices have been associated with operations on the window functions that arise in Gabor theory. In particular it has been shown that transformation from a rectangular to a quincunx lattice can be associated with fractional Fourier transformation. Since a Gaussian function,
Rectangular-to-quincunx Gabor lattice conversion via fractional Fourier transformation
Bastiaans, M.J.; Leest, van A.J.
1998-01-01
Transformations of Gabor lattices are associated with operations on the window functions that arise in Gabor theory. In particular it is shown that transformation from a rectangular to a quincunx lattice can be associated with fractional Fourier transformation. Since a Gaussian function, which plays
Numerical analysis and optimization of 3D magnetohydrodynamic flows in rectangular U-bend
International Nuclear Information System (INIS)
He, Qingyun; Feng, Jingchao; Chen, Hongli
2016-01-01
Highlights: • MHD flows in rectangular U bends have been investigated under specific magnetic field. • U bends analyzed with different aspect ratio, distance of U bends and the wall conductance ratio. • Pressure optimization of rectangular U bends at corner region. • Studying different inclination of magnetic field cases according to original MHD flows. - Abstract: Liquid metal flow in rectangular bends is a common phenomenon of fusion liquid metal blanket operation, in which the velocity distributions and magnetohydrodynamic (MHD) pressure drop are considered as critical issues. Previous studies mainly aimed at specific fixed geometry for bend flows in LM blanket. The present investigation focuses on numerical analysis of MHD flow in 3D rectangular bends at laminar conditions, which is aimed to reduce MHD pressure drop caused by electromagnetic coupling in conductive flow, especially in bend corner region. The used code has been developed by University of Science and Technology of China (USTC) and validated by recommended benchmark cases such as Shercliff, ALEX experiments and KIT experiment cases, etc. In order to search the optimal duct bending, certain parameters such as different aspect ratio of the duct corner area cross-section, distance of import and export from the elbow and wall conductance ratio have been considered to investigate the pressure drop of MHD flow. Moreover, the effects of different magnetic field direction relative to flow distribution between bends have also been analyzed.
The Effect of Mandrel Configuration on the Warpage in Pultrusion of Rectangular Hollow Profiles
Baran, Ismet; Hattel, Jesper H.; Akkerman, Remko
2014-01-01
Thermo-mechanical process simulation of an industrially pultruded rectangular hollow profile is presented. Glass/polyester is used for the continuous filament mat (CFM) and the uni-directional (UD) layers. The process induced residual distortions together with the temperature and degree of cure are
Regimes of Vorticity in the Wake of a Rectangular Vortex Generator
DEFF Research Database (Denmark)
Velte, Clara Marika; Okulov, Valery; Hansen, Martin Otto Laver
2011-01-01
This paper concerns the study of the secondary structures generated in the wake of a wall mounted rectangular vane, commonly referred to as a vortex generator. The study has been conducted by Stereoscopic PIV measurements in a wind tunnel and supplementary flow visualizations in a water channel...
Behavior of thin rectangular ANCF shell elements in various mesh configurations
DEFF Research Database (Denmark)
Hyldahl, Per; Mikkola, Aki M.; Balling, Ole
2014-01-01
a thorough review of three available formulations, they are used in three different convergence studies. Initially a reference study is conducted to determine how the ANCF performs in an uniform and rectangular mesh. Subsequently, the ANCF methods sensitivity to irregular mesh is investigated and finally...
Influence of magnetostatic interactions on the magnetization reversal of patterned magnetic elements
International Nuclear Information System (INIS)
Yin Xioalu; Liou, S. H.; Adeyeye, A. O.; Jain, S.; Han Baoshan
2011-01-01
The magnetization reversal in patterned thin-film arrays of elliptical submicron permalloy elements has been investigated by magnetic-force microscopy and micro-magneto-optic Kerr effect. Three different spatial arrangements of chains are considered, namely chains aligned parallel to the long axis of the ellipse, chains aligned parallel to the short axis of the ellipse, and arrays with roughly equal element-to-element spacings in both directions. Comparison of the hysteresis loops in an in-plane field perpendicular to the ellipses' long axes shows that the magnetization reversibility is highest for chains along the long axis. This is due to the nearly coherent magnetization rotation in the applied magnetic field and to the formation of a head-to-tail domain arrangement. Other arrangements, such as chains of ellipses aligned parallel to short axis, yield flux-closure domains as the applied magnetic field is changed.
DEFF Research Database (Denmark)
Dong, Yunfeng; Johansen, Tom Keinicke; Zhurbenko, Vitaliy
2016-01-01
This paper presents rectangular waveguide-to-coplanar waveguide (CPW) transitions at U-band (40–60 GHz) using E-plane probe and wire bonding. The designs of CPWs based on quartz substrate with and without aluminum cover are explained. The single and double layer rectangular waveguide-to-CPW trans......This paper presents rectangular waveguide-to-coplanar waveguide (CPW) transitions at U-band (40–60 GHz) using E-plane probe and wire bonding. The designs of CPWs based on quartz substrate with and without aluminum cover are explained. The single and double layer rectangular waveguide......-to-CPW transitions using E-plane probe and wire bonding are designed. The proposed rectangular waveguide-to-CPW transition using wire bonding can provide 10 GHz bandwidth at U-band and does not require extra CPWs or connections between CPWs and chips. A single layer rectangular waveguide-to-CPW transition using E......-plane probe with aluminum package has been fabricated and measured to validate the proposed transitions. To the authors' best knowledge, this is the first time that a wire bonding is used as a probe for rectangular waveguide-to-CPW transition at U-band....
Ezzaraa, K.; Bahlaoui, A.; Arroub, I.; Raji, A.; Hasnaoui, M.; Naïmi, M.
2018-05-01
In this work, we investigated numerically heat transfer by mixed convection coupled to thermal radiation in a vented rectangular enclosure uniformly heated from below with a constant heat flux. The fresh fluid is admitted into the cavity by injection or suction, by means of two openings located on the lower part of both right and left vertical sides. Another opening is placed on the middle of the top wall to ensure the ventilation. Air, a radiatively transparent medium, is considered to be the cooling fluid. The inner surfaces, in contact with the fluid, are assumed to be gray, diffuse emitters and reflectors of radiation with identical emissivities. The effects of some pertinent parameters such as the Reynolds number, 300 ≤ Re ≤ 5000, and the emissivity of the walls, 0 ≤ ɛ ≤ 0.85, on flow and temperature patterns as well as on the heat transfer rate within the enclosure are presented for the two ventilation modes (injection and suction). The results indicate that the flow and thermal structures are affected by the thermal radiation for the two modes of imposed flow. However, the suction mode is found to be more favorable to the heat transfer in comparison with the injection one.
DEFF Research Database (Denmark)
Nielsen, Sofus Birkedal; Celestinos, Adrian
2010-01-01
Rectangular rooms are the most common shape for sound reproduction, but at low frequencies the reflections from the boundaries of the room cause large spatial variations in the sound pressure level. Variations up to 30 dB are normal, not only at the room modes, but basically at all frequencies....... As sound propagates in time, it seems natural that the problems can best be analyzed and solved in the time domain. A time based room correction system named CABS (Controlled Acoustical Bass System) has been developed for sound reproduction in rectangular listening rooms. It can control the sound...... sound field in the whole room, and short impulse response. In a standard listening room (180 m3) only 4 loudspeakers are needed, 2 more than a traditional stereo setup. CABS is controlled by a developed DSP system. The time based approached might help with the understanding of sound field control...
Energy Technology Data Exchange (ETDEWEB)
Zhao, Guangpu [School of Mathematical Science, Inner Mongolia University, Hohhot, Inner Mongolia 010021 (China); Jian, Yongjun, E-mail: jianyj@imu.edu.cn [School of Mathematical Science, Inner Mongolia University, Hohhot, Inner Mongolia 010021 (China); Chang, Long [School of Mathematics and Statistics, Inner Mongolia University of Finance and Economics, Hohhot, Inner Mongolia 010051 (China); Buren, Mandula [School of Mathematical Science, Inner Mongolia University, Hohhot, Inner Mongolia 010021 (China)
2015-08-01
By using the method of separation of variables, an analytical solution for the magnetohydrodynamic (MHD) flow of the generalized Maxwell fluids under AC electric field through a two-dimensional rectangular micropump is reduced. By the numerical computation, the variations of velocity profiles with the electrical oscillating Reynolds number Re, the Hartmann number Ha, the dimensionless relaxation time De are studied graphically. Further, the comparison with available experimental data and relevant researches is presented. - Highlights: • MHD flow of the generalized Maxwell fluids under AC electric field is analyzed. • The MHD flow is confined to a two-dimensional rectangular micropump. • Analytical solution is obtained by using the method of separation of variables. • The influences of related parameters on the MHD velocity are discussed.
Feshchenko, R. M.
Recently a new exact transparent boundary condition (TBC) for the 3D parabolic wave equation (PWE) in rectangular computational domain was derived. However in the obtained form it does not appear to be unconditionally stable when used with, for instance, the Crank-Nicolson finite-difference scheme. In this paper two new formulations of the TBC for the 3D PWE in rectangular computational domain are reported, which are likely to be unconditionally stable. They are based on an unconditionally stable fully discrete TBC for the Crank-Nicolson scheme for the 2D PWE. These new forms of the TBC can be used for numerical solution of the 3D PWE when a higher precision is required.
International Nuclear Information System (INIS)
Qi, Jinyi; Klein, Gregory J.; Huesman, Ronald H.
2000-01-01
A positron emission mammography scanner is under development at our Laboratory. The tomograph has a rectangular geometry consisting of four banks of detector modules. For each detector, the system can measure the depth of interaction information inside the crystal. The rectangular geometry leads to irregular radial and angular sampling and spatially variant sensitivity that are different from conventional PET systems. Therefore, it is of importance to study the image properties of the reconstructions. We adapted the theoretical analysis that we had developed for conventional PET systems to the list mode likelihood reconstruction for this tomograph. The local impulse response and covariance of the reconstruction can be easily computed using FFT. These theoretical results are also used with computer observer models to compute the signal-to-noise ratio for lesion detection. The analysis reveals the spatially variant resolution and noise properties of the list mode likelihood reconstruction. The theoretical predictions are in good agreement with Monte Carlo results
Sound absorption effects in a rectangular enclosure with the foamed aluminum sheet absorber
International Nuclear Information System (INIS)
Oh, Jae Eung; Chung, Jin Tai; Kim, Sang Hun; Chung, Kyung Ryul
1998-01-01
For the purpose of finding out the optimal thickness of sound absorber and the sound absorption effects due to the selected thickness at an interested frequency range, the analytical study identifies the interior and exterior sound field characteristics of a rectangular enclosure with foamed aluminum lining and the experimental verification is performed with random noise input. By using a two-microphone impedance tube, we measure experimentally the absorption coefficient and the impedance of simple sound absorbing materials. Measured acoustical parameters of the test samples are applied to the theoretical analysis to predict sound pressure field in the cavity. The sound absorption effects from measurements are compared to predicted ones in both cases with and without foamed aluminum lining in the cavity of the rectangular enclosure
Integral transform solution of bending problem of clamped orthotropic rectangular plates
International Nuclear Information System (INIS)
An, C.; Gu, J.-J.; Su, J.
2011-01-01
The generalized integral transform technique (GITT) is employed to obtain an exact solution for the bending problem of fully clamped orthotropic rectangular plates. The use of the GITT approach in the analysis of the transverse deflection equation leads to a coupled system of fourth order differential equations in the dimensionless longitudinal spatial variable. The resulting transformed ODE system is then numerically solved by making use of the subroutine DBVPFD from IMSL Library. Numerical results with automatic global accuracy control are produced for different values of aspect ratio. Critical comparisons with previously reported numerical results are performed with excellent agreement. Several sets of reference results for clamped orthotropic rectangular plates are also provided for future covalidation purposes. (author)
Plasmonic band-stop filter with asymmetric rectangular ring for WDM networks
International Nuclear Information System (INIS)
Nezhad, Vahid Foroughi; Abrishamian, Mohammad Sadegh; Abaslou, Siamak
2013-01-01
We proposed a simple asymmetric rectangular band-stop filter based on metal–insulator–metal plasmonic waveguides. It is shown that the performance of the structure as a filter strongly depends on the asymmetry of the rectangular structure. An analytical model based on the analogy between MDM waveguides and the microwave transmission line is used to calculate the resonance wavelengths and explain the behavior of the filter. The bandwidth of spectra can be easily manipulated by adjusting the topological parameters of the filter. It is also demonstrated that by adjusting the bandwidth, the filter can be used for CWDM standard channels. The filter behavior is verified using the numerical finite difference time domain (FDTD) method. The filter is compact and has a footprint of 1 μm × 0.5 μm, which is suitable for integrated optical circuits. (paper)
Comparison of air-standard rectangular cycles with different specific heat models
International Nuclear Information System (INIS)
Wang, Chao; Chen, Lingen; Ge, Yanlin; Sun, Fengrui
2016-01-01
Highlights: • Air-standard rectangular cycle models are built and investigated. • Finite-time thermodynamics is applied. • Different dissipation models and variable specific heats models are adopted. • Performance characteristics of different cycle models are compared. - Abstract: In this paper, performance comparison of air-standard rectangular cycles with constant specific heat (SH), linear variable SH and non-linear variable SH are conducted by using finite time thermodynamics. The power output and efficiency of each cycle model and the characteristic curves of power output versus compression ratio, efficiency versus compression ratio, as well as power output versus efficiency are obtained by taking heat transfer loss (HTL) and friction loss (FL) into account. The influences of HTL, FL and SH on cycle performance are analyzed by detailed numerical examples.
Critical heat flux of subcooled flow boiling in narrow rectangular channels
International Nuclear Information System (INIS)
Kureta, Masatoshi; Akimoto, Hajime
1999-01-01
In relation to the high-heat-load devices such as a solid-target cooling channel of a high-intensity neutron source, burnout experiments were performed to obtain critical heat flux (CHF) data systematically for vertical upward flow in one-side heated rectangular channels. One of the objectives of this study was to study an extensibility of existing CHF correlations and models, which were proposed for a round tube, to rectangular channels for design calculation. Existing correlations and models were reviewed and compared with obtained data. Sudo's thin liquid layer dryout model, Griffel correlation and Bernath correlation were in good agreement with the experimental data for short-heated-length and low inlet water temperature conditions. (author)
Influence of old rectangular repair patches on the burst pressure of a gas pipeline
International Nuclear Information System (INIS)
Fazzini, Pablo Gabriel; Otegui, Jose Luis
2006-01-01
Seven full scale hydrostatic burst tests were carried out on pipes extracted from an API 5LX52 gas pipeline that contained rectangular and elliptical fillet welded patches and other repairs of different geometries. All breaks took place after widespread yielding. This analysis shows that the patches that generate greater risks are those that: (1) were attached to the pipeline at very low pressure (2) were placed to repair large defects (3) are rectangular, long in the direction of the pipe, and narrow (4) the quality of the weld is doubtful. Based on data reported by In Line Inspection (ILI), of the four conditions mentioned above, only the third can be assessed in order to quantify risks and to schedule replacements
Holmberg, Andreas; Karlsson, Mikael; Åbom, Mats
2015-03-01
Scattering matrices are determined experimentally and used to study the low-amplitude interaction, between the acoustic and the hydrodynamic fields in a T-junction of rectangular ducts. In particular, combinations of grazing and bias flows are investigated in the study. It is observed that for all flow combinations, waves incident on the junction at the downstream side only are attenuated, while waves incident at the other branches may be amplified or attenuated, depending on the Strouhal number. When bias in-flow is introduced to a grazing flow, there is first an increase and then a decrease in both amplification and attenuation, as the bias in-flow Mach number is increased. Comparing with T-junctions of circular ducts, the interaction is stronger for rectangular duct junctions.
Study on critical heat flux based on wavelet transform in rectangular narrow channels
International Nuclear Information System (INIS)
Zhou Tao; Ju Zhongyun; Zhang Lei; Li Jingjing; Sheng Cheng; Xiao Zejun
2014-01-01
Critical heat flux is very important for the safety of nuclear reactor, and observing temperature rise rate is a feasible method. The wavelet transform is used to analyze the CHF temperature rise curves in rectangular narrow channels, which can remove relative weaker interference and effectively judge CHF. Rectangular narrow channel can strengthen heat transfer and reduce CHF, whose characteristics are proved by temperature rise curves analyzed by wavelet transform. Respectively applying Daubechies function and Haar function is to guarantee the accuracy of the wavelet analysis, and Daubechies function is more accurate than Haar function in the detail signal processing from results. While the wavelet analysis and experimental results are compared and found in good agreement with the experimental results. (authors)
Study on critical heat flux based on wavelet transform in rectangular narrow channels
International Nuclear Information System (INIS)
Zhou Tao; Ju Zhongyun; Zhang Lei; Li Jingjing; Sheng Cheng; Xiao Zejun
2014-01-01
Critical heat flux is very important for nuclear reactor safety, and observing temperature rise rate is a feasible method. Through using the wavelet transform to analyze the CHF temperature rise curves in rectangular narrow channels, it can remove relative weaker interference and effectively judge CHF. Rectangular narrow channel can strengthen heat transfer and reduce CHF, whose characteristics are proved by, temperature rise curves analyzed by wavelet transform. Respectively applying Daubechies function and Haar function is for guarantee the accuracy of the wavelet analysis, and Daubechies function is more accurate than Haar function in the detail signal processing from results. While the wavelet analysis and experimental results are compared and found in good agreement with the experimental results. (authors)
Three-dimensional detonation cellular structures in rectangular ducts using an improved CESE scheme
Shen, Yang
2016-11-01
The three-dimensional premixed H2-O2 detonation propagation in rectangular ducts is simulated using an in-house parallel detonation code based on the second-order space–time conservation element and solution element (CE/SE) scheme. The simulation reproduces three typical cellular structures by setting appropriate cross-sectional size and initial perturbation in square tubes. As the cross-sectional size decreases, critical cellular structures transforming the rectangular or diagonal mode into the spinning mode are obtained and discussed in the perspective of phase variation as well as decreasing of triple point lines. Furthermore, multiple cellular structures are observed through examples with typical aspect ratios. Utilizing the visualization of detailed three-dimensional structures, their formation mechanism is further analyzed.
Positronium behaviour in elongated PPT, rectangular MgO and spherical Si nanocavities
International Nuclear Information System (INIS)
Eijt, S.W.H.; Falub, C.V.; Mijnarends, P.E.; Veen, A. van
2001-01-01
The 2D-ACAR para-Ps (p-Ps) spectrum of PPT aramid fibres, which contain structural elongated open spaces in the unit cell, is compared with the spectrum calculated for a Ps wave function in a rectangular cavity. Helium ion implantation in MgO and Si single crystals creates thin layers of nanosize rectangular and spherical cavities, respectively. Depth-selective 2D-ACAR experiments at the positron centre Delft allow the extraction of the p-Ps contribution from the spectra. In both samples p-Ps is not thermalised and has an average energy of the order of a few eV. The energy and momentum distribution of the Ps atoms are extracted and compared with Maxwell distributions. (orig.)
Positronium behaviour in elongated PPT, rectangular MgO and spherical Si nanocavities
Energy Technology Data Exchange (ETDEWEB)
Eijt, S.W.H.; Falub, C.V.; Mijnarends, P.E.; Veen, A. van [Interfaculty Reactor Inst., Delft Univ. of Technology (Netherlands)
2001-07-01
The 2D-ACAR para-Ps (p-Ps) spectrum of PPT aramid fibres, which contain structural elongated open spaces in the unit cell, is compared with the spectrum calculated for a Ps wave function in a rectangular cavity. Helium ion implantation in MgO and Si single crystals creates thin layers of nanosize rectangular and spherical cavities, respectively. Depth-selective 2D-ACAR experiments at the positron centre Delft allow the extraction of the p-Ps contribution from the spectra. In both samples p-Ps is not thermalised and has an average energy of the order of a few eV. The energy and momentum distribution of the Ps atoms are extracted and compared with Maxwell distributions. (orig.)
Directory of Open Access Journals (Sweden)
Zhong-Qi Yue
2012-01-01
Full Text Available This paper presents the stress and displacement fields in a functionally graded material (FGM caused by a load. The FGM is a graded material of Si3N4-based ceramics and is assumed to be of semi-infinite extent. The load is a distributed loading over a rectangular area that is parallel to the external surface of the FGM and either on its external surface or within its interior space. The point-load analytical solutions or so-called Yue’s solutions are used for the numerical integration over the distributed loaded area. The loaded area is discretized into 200 small equal-sized rectangular elements. The numerical integration is carried out with the regular Gaussian quadrature. Weak and strong singular integrations encountered when the field points are located on the loaded plane, are resolved with the classical methods in boundary element analysis. The numerical integration results have high accuracy.
Three-dimensional detonation cellular structures in rectangular ducts using an improved CESE scheme
International Nuclear Information System (INIS)
Shen Yang; Liu Kai-Xin; Chen Pu; Shen Hua; Zhang De-Liang
2016-01-01
The three-dimensional premixed H 2 -O 2 detonation propagation in rectangular ducts is simulated using an in-house parallel detonation code based on the second-order space–time conservation element and solution element (CE/SE) scheme. The simulation reproduces three typical cellular structures by setting appropriate cross-sectional size and initial perturbation in square tubes. As the cross-sectional size decreases, critical cellular structures transforming the rectangular or diagonal mode into the spinning mode are obtained and discussed in the perspective of phase variation as well as decreasing of triple point lines. Furthermore, multiple cellular structures are observed through examples with typical aspect ratios. Utilizing the visualization of detailed three-dimensional structures, their formation mechanism is further analyzed. (paper)
Realization of Rectangular Artificial Spin Ice and Direct Observation of High Energy Topology.
Ribeiro, I R B; Nascimento, F S; Ferreira, S O; Moura-Melo, W A; Costa, C A R; Borme, J; Freitas, P P; Wysin, G M; de Araujo, C I L; Pereira, A R
2017-10-25
In this work, we have constructed and experimentally investigated frustrated arrays of dipoles forming two-dimensional artificial spin ices with different lattice parameters (rectangular arrays with horizontal and vertical lattice spacings denoted by a and b respectively). Arrays with three different aspect ratios γ = a/b = [Formula: see text], [Formula: see text] and [Formula: see text] are studied. Theoretical calculations of low-energy demagnetized configurations for these same parameters are also presented. Experimental data for demagnetized samples confirm most of the theoretical results. However, the highest energy topology (doubly-charged monopoles) does not emerge in our theoretical model, while they are seen in experiments for large enough γ. Our results also insinuate that the string tension connecting two magnetic monopoles in a pair vanishes in rectangular lattices with a critical ratio γ = γ c = [Formula: see text], supporting previous theoretical predictions.
DEFF Research Database (Denmark)
Maftei, Elena; Pop, Paul; Madsen, Jan
2010-01-01
they are highly reconfigurable and scalable. A digital biochip is composed of a two-dimensional array of cells, together with reservoirs for storing the samples and reagents. Several adjacent cells are dynamically grouped to form a virtual device, on which operations are performed. So far, researchers have...... assumed that throughout its execution, an operation is performed on a rectangular virtual device, whose position remains fixed. However, during the execution of an operation, the virtual device can be reconfigured to occupy a different group of cells on the array, forming any shape, not necessarily...... rectangular. In this paper, we present a Tabu Search metaheuristic for the synthesis of digital microfluidic biochips, which, starting from a biochemical application and a given biochip architecture, determines the allocation, resource binding, scheduling and placement of the operations in the application...
MHD and heat transfer benchmark problems for liquid metal flow in rectangular ducts
International Nuclear Information System (INIS)
Sidorenkov, S.I.; Hua, T.Q.; Araseki, H.
1994-01-01
Liquid metal cooling systems of a self-cooled blanket in a tokamak reactor will likely include channels of rectangular cross section where liquid metal is circulated in the presence of strong magnetic fields. MHD pressure drop, velocity distribution and heat transfer characteristics are important issues in the engineering design considerations. Computer codes for the reliable solution of three-dimensional MHD flow problems are needed for fusion relevant conditions. Argonne National Laboratory and The Efremov Institute have jointly defined several benchmark problems for code validation. The problems, described in this paper, are based on two series of rectangular duct experiments conducted at ANL; one of the series is a joint ANL/Efremov experiment. The geometries consist of variation of aspect ratio and wall thickness (thus wall conductance ratio). The transverse magnetic fields are uniform and nonuniform in the axial direction
Size effect of the elastic modulus of rectangular nanobeams: Surface elasticity effect
International Nuclear Information System (INIS)
Yao Hai-Yan; Fan Wen-Liang; Yun Guo-Hong
2013-01-01
The size-dependent elastic property of rectangular nanobeams (nanowires or nanoplates) induced by the surface elasticity effect is investigated by using a developed modified core-shell model. The effect of surface elasticity on the elastic modulus of nanobeams can be characterized by two surface related parameters, i.e., inhomogeneous degree constant and surface layer thickness. The analytical results show that the elastic modulus of the rectangular nanobeam exhibits a distinct size effect when its characteristic size reduces below 100 nm. It is also found that the theoretical results calculated by a modified core-shell model have more obvious advantages than those by other models (core-shell model and core-surface model) by comparing them with relevant experimental measurements and computational results, especially when the dimensions of nanostructures reduce to a few tens of nanometers. (condensed matter: structural, mechanical, and thermal properties)
International Nuclear Information System (INIS)
Zhao, Guangpu; Jian, Yongjun; Chang, Long; Buren, Mandula
2015-01-01
By using the method of separation of variables, an analytical solution for the magnetohydrodynamic (MHD) flow of the generalized Maxwell fluids under AC electric field through a two-dimensional rectangular micropump is reduced. By the numerical computation, the variations of velocity profiles with the electrical oscillating Reynolds number Re, the Hartmann number Ha, the dimensionless relaxation time De are studied graphically. Further, the comparison with available experimental data and relevant researches is presented. - Highlights: • MHD flow of the generalized Maxwell fluids under AC electric field is analyzed. • The MHD flow is confined to a two-dimensional rectangular micropump. • Analytical solution is obtained by using the method of separation of variables. • The influences of related parameters on the MHD velocity are discussed
Jalinous, Reza; Lisanby, Sarah H.
2013-01-01
A novel transcranial magnetic stimulation (TMS) device with controllable pulse width (PW) and near rectangular pulse shape (cTMS) is described. The cTMS device uses an insulated gate bipolar transistor (IGBT) with appropriate snubbers to switch coil currents up to 7 kA, enabling PW control from 5 μs to over 100 μs. The near-rectangular induced electric field pulses use 22–34% less energy and generate 67–72% less coil heating compared to matched conventional cosine pulses. CTMS is used to stimulate rhesus monkey motor cortex in vivo with PWs of 20 to 100 μs, demonstrating the expected decrease of threshold pulse amplitude with increasing PW. The technological solutions used in the cTMS prototype can expand functionality, and reduce power consumption and coil heating in TMS, enhancing its research and therapeutic applications. PMID:18232369
Huang, Yen-Chieh; Wang, Tsong-Dong; Lin, Yen-Hou; Lee, Ching-Han; Chuang, Ming-Yun; Lin, Yen-Yin; Lin, Fan-Yi
2011-11-21
We report forward and backward THz-wave difference frequency generations at 197 and 469 μm from a PPLN rectangular crystal rod with an aperture of 0.5 (height in z) × 0.6 (width in y) mm(2) and a length of 25 mm in x. The crystal rod appears as a waveguide for the THz waves but as a bulk material for the optical mixing waves near 1.54 μm. We measured enhancement factors of 1.6 and 1.8 for the forward and backward THz-wave output powers, respectively, from the rectangular waveguide in comparison with those from a PPLN slab waveguide of the same length, thickness, and domain period under the same pump and signal intensity of 100 MW/cm(2). © 2011 Optical Society of America
Resonant frequency function of thickness-shear vibrations of rectangular crystal plates.
Wang, Ji; Yang, Lijun; Pan, Qiaoqiao; Chao, Min-Chiang; Du, Jianke
2011-05-01
The resonant frequencies of thickness-shear vibrations of quartz crystal plates in rectangular and circular shapes are always required in the design and manufacturing of quartz crystal resonators. As the size of quartz crystal resonators shrinks, for rectangular plates we must consider effects of both length and width for the precise calculation of resonant frequency. Starting from the three-dimensional equations of wave propagation in finite crystal plates and the general expression of vibration modes, we obtained the relations between frequency and wavenumbers. By satisfying the major boundary conditions of the dominant thickness-shear mode, three wavenumber solutions are obtained and the frequency equation is constructed. It is shown the resonant frequency of thickness-shear mode is a second-order polynomial of aspect ratios. This conforms to known results in the simplest form and is applicable to further analytical and experimental studies of the frequency equation of quartz crystal resonators.
Effect of aspect ratio on the laminar-to-turbulent transition in rectangular channel
International Nuclear Information System (INIS)
Wang Chang; Gao Puzhen; Tan Sichao; Xu Chao
2012-01-01
Highlights: ► Effect of aspect ratio on the transition Reynolds number in rectangular channel is studied. ► Prediction correlation for transition Reynolds number is proposed. ► The initiation location of flow transition is studied. - Abstract: The critical Reynolds number of the laminar-to-turbulent transition in the rectangular channel is investigated based on the energy gradient method. The results show that the critical Reynolds number decreases with the increasing aspect ratio. However, the relative location of laminar breakdown does not migrate significantly with the variation of the aspect ratio. In addition, a theoretical correlation as a function of the aspect ratio is proposed to calculate the transition Reynolds number, and the predicted values are in good agreement with the experimental data obtained in the published literatures.
Turbulent slurry flow measurement using ultrasonic Doppler method in rectangular pipe
Bareš, V.; Krupička, J.; Picek, T.; Brabec, J.; Matoušek, V.
2014-03-01
Distribution of velocity and Reynolds stress was measured using ultrasonic velocimetry in flows of water and Newtonian water-ballotini slurries in a pressurized Plexiglas pipe. Profiles of the measured parameters were sensed in the vertical plane at the centreline of a rectangular cross section of the pipe. Reference measurements in clear water produced expected symmetrical velocity profiles the shape of which was affected by secondary currents developed in the rectangular pipe. Slurry-flow experiments provided information on an effect of the concentration of solid grains on the internal structure of the flow. Strong attenuation of velocity fluctuations caused by a presence of grains was identified. The attenuation increased with the increasing local concentration of the grains.
Three-dimensional detonation cellular structures in rectangular ducts using an improved CESE scheme
Shen, Yang; Shen, Hua; Liu, Kai Xin; Chen, Pu; Zhang, De Liang
2016-01-01
The three-dimensional premixed H2-O2 detonation propagation in rectangular ducts is simulated using an in-house parallel detonation code based on the second-order space–time conservation element and solution element (CE/SE) scheme. The simulation reproduces three typical cellular structures by setting appropriate cross-sectional size and initial perturbation in square tubes. As the cross-sectional size decreases, critical cellular structures transforming the rectangular or diagonal mode into the spinning mode are obtained and discussed in the perspective of phase variation as well as decreasing of triple point lines. Furthermore, multiple cellular structures are observed through examples with typical aspect ratios. Utilizing the visualization of detailed three-dimensional structures, their formation mechanism is further analyzed.
High-voltage nanosecond Marx generator with quasi-rectangular pulses
International Nuclear Information System (INIS)
Bulan, V.V.; Grabovskij, E.V.; Gribov, A.N.; Luzhnov, V.G.
1999-01-01
The automated high-voltage nanosecond generator, forming single pulses of any polarity on the load of 17 Ohm with polarity voltage from 100 up to 300 kV at the semiheight of 80 ns and the front of 7 ns is described. The generator is assembled on the basis of low-inductive capacitors, which by discharge form the pulse, close by form to rectangular one [ru
Energy Technology Data Exchange (ETDEWEB)
D' Ettorre Piazzoli, B; Mannocchi, G [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Melone, S [Istituto di Fisica dell' Universita, Ancona, Italy; Picchi, P; Visentin, R [Comitato Nazionale per l' Energia Nucleare, Frascati (Italy). Laboratori Nazionali di Frascati
1976-06-01
Expressions for the counting rate of rectangular telescopes in the case of single as well as multiple particles are given. The aperture for single particles is obtained in the form of a double integral and analytical solutions are given for some cases. The intensity for different multiplicities of parallel particles is related to the geometry of the detectors and to the features of the radiation. This allows an absolute comparison between the data recorded by different devices.
International Nuclear Information System (INIS)
Buzbee, B.L.; Dorr, F.W.
1974-01-01
The discrete biharmonic equation on a rectangular region and the discrete Poisson equation on an irregular region can be treated as modifications to matrix problems with very special structure. It is shown how to use the direct method of matrix decomposition to formulate an effective numerical algorithm for these problems. For typical applications the operation count is O(N 3 ) for an N x N grid. Numerical comparisons with other techniques are included. (U.S.)
Slug-annular transition with particular reference to narrow rectangular ducts
International Nuclear Information System (INIS)
Jones, O.C. Jr.; Zuber, N.
1978-01-01
The transition from slug-flow to annular-flow in two-phase, gas-liquid mixtures is analyzed. A transition equation is derived which agrees well when compared with objective data determined from the disappearance of the low-void peak in the void fluctuation probability density in a rectangular duct. Application to other geometries is suggested and tabular recommendations given for determination of the drift flux coefficient, K, based on results in the literature
Forced convective boiling heat transfer of water in vertical rectangular narrow channel
International Nuclear Information System (INIS)
Chen, Chong; Gao, Pu-zhen; Tan, Si-chao; Chen, Han-ying; Chen, Xian-bing
2015-01-01
Highlights: • Chen correlation cannot well predict the coefficient of rectangular channel. • Kim and Mudawar correlation is the best one among the Chen type correlations. • Lazarek and Black correlation predicted 7.0% of data within the ±30% error band. • The new correlation can well predict the coefficient with a small MAE of 14.4%. - Abstract: In order to research the characteristics of boiling flows in a vertical rectangular narrow channel, a series of convective boiling heat transfer experiments are performed. The test section is made of stainless steel with an inner diameter of 2 × 40 mm and heated length of 1100 mm. The 3194 experimental data points are obtained for a heat flux range of 10–700 kW/m 2 , a mass flux range of 200–2400 kg/m 2 s, a system pressure range of 0.1–2.5 MPa, and a quality range of 0–0.8. Eighteen prediction models are used to predict the flow boiling heat transfer coefficient of the rectangular narrow channel and the predicted value is compared against the database including 3194 data points, the results show that Chen type correlations and Lazarek and Black type correlations are not suitable for the rectangular channel very much. The Kim and Mudawar correlation is the best one among the 18 models. A new correlation is developed based on the superposition concept of nucleate boiling and convective boiling. the new correlation is shown to provide a good prediction against the database, evidenced by an overall MAE of 14.4%, with 95.2% and 98.6% of the data falling within ±30% and ±35% error bands, respectively
Rectangular Gusset Plate Behaviour in Cold-Formed I-Type Steel Connections
Directory of Open Access Journals (Sweden)
Bučmys Ž.
2017-06-01
Full Text Available Cold-formed structure connections utilizing gusset plates are usually semi-rigid. This paper investigates the behaviours of rectangular gusset plates in cold-formed connections of elements whose columns and beams are made with lipped back-to-back C-sections. Methods of calculating strength and stiffness are necessary for such semi-rigid joints. The main task of this paper is to determine a method capable of calculating these characteristics. The proposed analytical method could then be easily adapted to the component method that is described in part 1993-1-8 of the Eurocode. This method allows us to calculate both the strength and stiffness of rectangular gusset plates, assuming that the joint deforms only in plane. This method of design moment resistance calculation was presented taking into account that an entire cross-section shall reach its yield stress. A technique of stiffness calculation was presented investigating the sum of deformations acquired at the bending moment and from shear forces which are transmitted from each beam bolt group. Calculation results according to the suggested method show good agreement of laboratory experimental results of specimens with numerical simulations. Two specimens of beam-to-column connections were tested in the laboratory. Lateral supports were used on the specimens to prevent lateral displacements in order to better investigate the behaviour of the rectangular gusset plate in plane. Experiments were simulated by modelling rectangular gusset plates using standard finite element software ANSYS Workbench 14.0. Three-dimensional solid elements were used for modelling and both geometric and material nonlinear analysis was performed.
Total reflection and cloaking by zero index metamaterials loaded with rectangular dielectric defects
Wu, Ying
2013-05-06
In this work, we investigate wave transmission property through a zero index metamaterial (ZIM) waveguide embedded with rectangular dielectric defects. We show that total reflection and total transmission (cloaking) can be achieved by adjusting the geometric sizes and/or permittivities of the defects. Our work provides another possibility of manipulating wave propagation through ZIM in addition to the widely studied dielectric defects with cylindrical geometries.
Release of metal ions from round and rectangular NiTi wires
Directory of Open Access Journals (Sweden)
Arash Azizi
2016-04-01
Full Text Available Abstract Background The aim of this study was to evaluate the amount of nickel and titanium ions released from two wires with different shapes and a similar surface area. Methods Forty round nickel-titanium (NiTi arch wires with the diameter of 0.020 in. and 40 rectangular NiTi arch wires with the diameter of 0.016 × 0.016 in. were immersed in artificial saliva during a 21-day period. The surface area of both wires was 0.44 in.2. Wires were separately dipped into polypropylene tubes containing 50 ml of buffer solution and were incubated and maintained at 37 °C. Inductively coupled plasma atomic emission spectrometry (ICP-AES was used to measure the amount of ions released after exposure lengths of 1 h, 24 h, 1 week, and 3 weeks. Repeated measures ANOVA and Tukey tests were used to evaluate the data. Results The results indicated that the amount of nickel and titanium concentrations was significantly higher in the rectangular wire group. The most significant release of all metals was measured after the first hour of immersion. In the rectangular wire group, 243 ± 4.2 ng/ml of nickel was released after 1 h, while 221.4 ± 1.7 ng/ml of nickel was released in the round wire group. Similarly, 243.3 ± 2.8 ng/ml of titanium was released in the rectangular wire group and a significantly lower amount of 211.9 ± 2.3 ng/ml of titanium was released in the round wire group. Conclusions Release of metal ions was influenced by the shape of the wire and increase of time.
Thermal stresses in an orthotropic rectangular plate with a rigid ribbonlike inclusion
International Nuclear Information System (INIS)
Sumi, N.
1981-01-01
On the basis of the complex variable method for determining the stationary two-dimensional thermal stresses, the thermal stresses in an orthotropic rectangular plate with a rigid ribbonlike inclusion under a steady state temperature field is considered. The solution is found by the analytic continuation argument and the modified mapping-collocation technique. Numerical results indicate a dependence of the orthotropic stress intensity factors on the thermal, elastic and geometrical constants over a certain parameter range. (orig.)
Influence of a circular jet arrangement in a rectangular tank on flow and suspended sediment release
Althaus, Jenzer; Isabella, Jolanda Maria
2011-01-01
With the objective of high sediment release out of a rectangular tank the performance of a circular jet arrangement has been investigated. Therefore, experiments with four jets arranged in a horizontal circle placed in water with quasi homogeneous sediment concentration were conducted. The induced circulation was analysed by measuring the flow field. The influence of the flow circulation on suspension and on sediment release through the water intake was studied and discussed. The offbottom cl...
Transmission line model for coupled rectangular double split‐ring resonators
DEFF Research Database (Denmark)
Yan, Lei; Tang, Meng; Krozer, Viktor
2011-01-01
In this work, a model based on a coupled transmission line formulation is developed for microstrip rectangular double split‐ring resonators (DSRRs). This model allows using the physical dimensions of the DSRRs as an input avoiding commonly used extraction of equivalent parameters. The model inclu...... simulations of the DSRR structures. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1311–1315, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25988...
Huixing Li; Yu Liu
2016-01-01
In order to investigate the characteristics of boiling heat transfer for hydrocarbon mixture refrigerant in plate-fin heat exchanger which is used in the petrochemical industry field, a model was established on boiling heat transfer in vertical rectangular channel. The simulated results were compared with the experimental data from literature. The results show that the deviation between the simulated results and experimental data is within ±15%. Meanwhile, the characteristic of boiling heat t...
Ayat, Sabrina S; Wrobel, Rafal; Goss, James; Drury, David
2016-01-01
In order to improve accuracy and reduce model setting-up, and solving time in thermal analysis of electrical machines, transformers and wound passive components, the multi-material winding region is frequently homogenised. The existing winding homogenization techniques are predo-minantly focused on winding constructions with round conductors, where thermal conductivity across conductors is usually assumed to be isotropic. However, for the profiled rectangular conductors that assumption is no ...
Experimental verification of the axial and lateral stiffness of large W7-X rectangular bellows
International Nuclear Information System (INIS)
Reich, J.; Cardella, A.; Koppe, T.; Missal, B.; Capriccioli, A.; Loehrer, W.; Langone, S.; Sassone, P.C.
2006-01-01
The WENDELSTEIN 7-X (W7-X) is a super-conducting helical advanced stellarator. W7-X is provided with 299 ports, which connect the plasma vessel with the outer vessel. All the ports are equipped with bellows, which, during bake-out and final adjustment, compensate the relative movements of the vessels. The bellows have different shapes and dimensions ranging from 100 mm circular to 1170 x 570 mm rectangular sizes. During various load-cases the axial and lateral stiffness of all bellows will create a resulting spring-force which acts on the supports of the vessels directly. The higher the stiffness the more is the significant influence on the supports. The lateral stiffness which was calculated with the established standard EJMA-code (Expansion Joint Manufacturers Association) seemed to be relatively small. This appeared to be not correct in particular for non circular bellows. That is why the stiffness of rectangular, multi-layer bellows have then been re-calculated with the Finite Element Method (FEM) code ANSYS. The maximum difference between the FEM and EJMA code resulted to be up to 250 % in particular with movements along the longer side of the bellows. In order to clarify the differences a test-campaign with the largest rectangular bellows was performed. A special test rack allowed predefined displacements in pure lateral and axial directions taking into consideration of the friction in the moving elements. During the tests the load-displacement diagram was recorded permanently. The outcome of the FEM-results was then verified by the tests in axial and lateral directions. The EJMA-code is well proved for circular bellows. The tests showed that instead any calculation of rectangular bellows has to be confirmed by experiments. The paper summarises the calculation, describes the test activities, the apparatus and reports the final results. (author)
Environmental Effects on Flutter Characteristics of Laminated Composite Rectangular and Skew Panels
Directory of Open Access Journals (Sweden)
T.V.R. Chowdary
1996-01-01
Full Text Available A finite element method is presented for predicting the flutter response of laminated composite panels subjected to moisture concentration and temperature. The analysis accounts for material properties at elevated temperature and moisture concentration. The analysis is based on the first-order approximation to the linear piston theory and laminated plate theory that includes shear deformation. Both rectangular and skew panels are considered. Stability boundaries at moisture concentrations and temperatures for various lamination schemes and boundary conditions are discussed.
On the evaluation of rectangular plane-extended sources and their associated radiation fields
International Nuclear Information System (INIS)
Oner, Feda
2007-01-01
The objective of this paper is to provide an efficient and reliable analytical procedure for the evaluation of rectangular plane-extended sources and their associated radiation fields. Integrals with integer and non-integer values appear in the evaluation of the radiation field distribution. The latter results from a homogeneous rectangular plane target bombarded by hollow-cylindrical ion beams, the elementary areas anisotropically emitting in non-dispersive media, and fast neutrons produced in non-dispersive media by sealed-off neutron generating tubes (NGT) in an axi-symmetric situation [Hubbell, J.H., Bach, R.L., Lamkin, J.C., 1960. Radiation from a rectangular source. J. Res. NBS 64C (2), 121-137; Hubbell, J.H., 1963a. A power series buildup factor formulation. Application to rectangular and offaxis disk source problems. J. Res. NBS 67C, 291-306, Hubbell, J.H., 1963b. Dose fields from plane sources using point-source data. Nucleonics 21 (8), 144-148; Timus et al., 2005a. Plane rectengular tritium target response to excitation by uniform distributed normal accelerated deuteron beam. Appl. Radiat. Isot. 63, 823-839; Timus et al., 2005b. Analytical characterization of radiation fields generated by certain witch-type distributed axi-symmetrical ion beams. Arab J. Nucl. Sci. Appl. 38(I) 253-264]. In these references, the resulting expressions are represented as infinite linear combinations of basic J q (a, b, z) integrals. With the help of relation for J q (a, b, z), we can evaluate the high terms of energy expressions, which have been proposed in the above-mentioned references. The extensive test calculations show that the proposed algorithm in this work is the most efficient one in practical computations
Total reflection and cloaking by zero index metamaterials loaded with rectangular dielectric defects
Wu, Ying; Li, Jichun
2013-01-01
In this work, we investigate wave transmission property through a zero index metamaterial (ZIM) waveguide embedded with rectangular dielectric defects. We show that total reflection and total transmission (cloaking) can be achieved by adjusting the geometric sizes and/or permittivities of the defects. Our work provides another possibility of manipulating wave propagation through ZIM in addition to the widely studied dielectric defects with cylindrical geometries.
International Nuclear Information System (INIS)
Choi, Hang Seok; Park, Tae Seon
2013-01-01
Highlights: ► With changing aspect ratio, the effect of secondary flows on the turbulent heat transfer is scrutinized by a LES. ► The conditional sampling technique of instantaneous near-wall streamwise vortices is developed. ► Clockwise and counter-clockwise rotating streamwise vortices are sampled and discussed with the wall heat transfer. ► The hot-sweep motions of CW and CCW vortices clearly appear with increasing aspect ratio. -- Abstract: The effect of aspect ratio of rectangular duct on the turbulent flow and heat transfer is very important for its engineering applications. But the turbulent thermal fields have not been fundamentally scrutinized in spite of its engineering significance especially for cooling device. Hence, in the present study, large eddy simulation is applied to the turbulent flow and heat transfer in rectangular ducts with varying aspect ratio. The turbulent statistics of the flow and thermal quantities are calculated and the characteristics of wall Nusselt number are investigated for each rectangular duct. Especially, to scrutinize near-wall streamwise vortices, a conditional sampling technique is developed and adopted. Clockwise and counter-clockwise rotating streamwise vortices are sampled and the probability density function of the vortex circulation Reynolds number and wall Nusselt number are calculated. From the results, the time-averaged secondary flow caused by instantaneous vortical motions has a great effect on the heat and momentum transport of the flow in the rectangular ducts. Hence, the wall Nusselt number is enhanced near the downwash flow region of the secondary flow. However, with increasing the aspect ratio, the effects of the hot-sweep flow of the clockwise and counter-clockwise rotating vortices become equally dominant near the wall normal bisector of the ducts. During time averaging process, these two counter-rotating vortices are canceled out each other diminishing a secondary flow but they still enhance the
Kostichev, P. I.; Poddubnyi, I. I.; Razuvanov, N. G.
2017-11-01
In some DEMO blanket designs liquid metal flows in vertical ducts of rectangular cross-section between ceramic breeder units providing their cooling. Heat exchange in these conditions is governed by the influence of magnetic field (coplanar) and by buoyancy effects that depend on the flow orientation to the gravity vector (downward and upward flow). Magnetohydrodynamic and heat transfer of liquid metal in vertical rectangular ducts is not well researched. Experimental study of buoyancy effects in rectangular duct with coplanar magnetic field for one-sided heat load and downward and upward flowsis presented in this paper. The detail research with has been done on mercury MHD close loop with using of the probe technique allow to discover several advantageous and disadvantageous effects. The intensive impact of buoyancy force has been observed in a few regime of downward flow which has been laminarized by magnetic field. Due to the development in the flow of the secondary large-scale vortices heat transfer improved and the temperature fluctuations of the abnormally high intensity have been fixed. On the contrary, in the upward flow the buoyancy force stabilized the flow which lead to decreasing of the turbulence heat transfer ratio and, consequently, deterioration of heat transfer.
Development of a design methodology for hydraulic pipelines carrying rectangular capsules
International Nuclear Information System (INIS)
Asim, Taimoor; Mishra, Rakesh; Abushaala, Sufyan; Jain, Anuj
2016-01-01
The scarcity of fossil fuels is affecting the efficiency of established modes of cargo transport within the transportation industry. Efforts have been made to develop innovative modes of transport that can be adopted for economic and environmental friendly operating systems. Solid material, for instance, can be packed in rectangular containers (commonly known as capsules), which can then be transported in different concentrations very effectively using the fluid energy in pipelines. For economical and efficient design of such systems, both the local flow characteristics and the global performance parameters need to be carefully investigated. Published literature is severely limited in establishing the effects of local flow features on system characteristics of Hydraulic Capsule Pipelines (HCPs). The present study focuses on using a well validated Computational Fluid Dynamics (CFD) tool to numerically simulate the solid-liquid mixture flow in both on-shore and off-shore HCPs applications including bends. Discrete Phase Modelling (DPM) has been employed to calculate the velocity of the rectangular capsules. Numerical predictions have been used to develop novel semi-empirical prediction models for pressure drop in HCPs, which have then been embedded into a robust and user-friendly pipeline optimisation methodology based on Least-Cost Principle. - Highlights: • Local flow characteristics in a pipeline transporting rectangular capsules. • Development of prediction models for the pressure drop contribution of capsules. • Methodology developed for sizing of Hydraulic Capsule Pipelines. • Implementation of the developed methodology to obtain optimal pipeline diameter.
Directory of Open Access Journals (Sweden)
Niya Ma
2018-02-01
Full Text Available Developing a three-dimensional laminar flow in the entrance region of rectangular microchannels has been investigated in this paper. When the hydrodynamic development length is the same magnitude as the microchannel length, entrance effects have to be taken into account, especially in relatively short ducts. Simultaneously, there are a variety of non-continuum or rarefaction effects, such as velocity slip and temperature jump. The available data in the literature appearing on this issue is quite limited, the available study is the semi-theoretical approximate model to predict pressure drop of developing slip flow in rectangular microchannels with different aspect ratios. In this paper, we apply the lattice Boltzmann equation method (LBE to investigate the developing slip flow through a rectangular microchannel. The effects of the Reynolds number (1 < Re < 1000, channel aspect ratio (0 < ε < 1, and Knudsen number (0.001 < Kn < 0.1 on the dimensionless hydrodynamic entrance length, and the apparent friction factor, and Reynolds number product, are examined in detail. The numerical solution of LBM can recover excellent agreement with the available data in the literature, which proves its accuracy in capturing fundamental fluid characteristics in the slip-flow regime.
The analysis of radiation parameters dependence of rectangular waveguide on its dimensions change
Directory of Open Access Journals (Sweden)
Manoilov V.P.
2016-04-01
Full Text Available Analysis of radiation from 3 centimeter waveband rectangular waveguide at the change of the side sizes is carried out for the purpose of efficiency estimation of its use as reflector parabolic antenna exciter. Some performance characteristics of radioelectronic systems depend on antennas types which are used. Recently, the development of antenna systems occurred mainly not by creating new, and by improving the parameters and characteristics of existing antennas. Therefore, there is a practical need to find ways to improve their elements. A detailed analysis of the radiation from the open end of the rectangular waveguide allows to specify exactly which of its parameters and characteristics need to be improved. Dependence charts of directional diagram (DD in planes E and H, radiation power, directivity upon variation of side sizes a, b are received. Dependence charts of attenuation coefficient upon frequency for wave types H10, H01, H02, H11, E11 are drawn up. Estimation of reasonability of using rectangular waveguide as reflector parabolic antenna exciter is received.
VIBRATION CONTROL OF RECTANGULAR CROSS-PLY FRP PLATES USING PZT MATERIALS
Directory of Open Access Journals (Sweden)
DILEEP KUMAR K
2017-12-01
Full Text Available Piezoelectric materials are extensively employed in the field of structures for condition monitoring, smart control and testing applications. The piezoelectric patches are surface bonded to a composite laminate plate and used as vibration actuators. The coupling effects between the mechanical and electric properties of piezoelectric materials have drawn significant attention for their potential applications. In the present work, an analytical solution of the vibration response of a simply supported laminate rectangular plate under time harmonic electrical loading is obtained and a concept is developed for an approximate dynamic model to the vibration response of the simply supported orthotropic rectangular plates excited by a piezoelectric patch of variable rectangular geometry and location. A time harmonic electric voltages with the same magnitude and opposite sign are applied to the two symmetric piezoelectric actuators, which results in the bending moment on the plate. The main objective of the work is to obtain an analytical solution for the vibration amplitude of composite plate predicted from plate theory. The results demonstrate that the vibration modes can be selectively excited and the geometry of the PZTactuator shape remarkably affects the distribution of the response among modes. Thus according to the desired degree shape control it is possible to tailor the shape, size and properly designed control algorithm of the actuator to either excite or suppress particular modes.
International Nuclear Information System (INIS)
Miele, M.; Laymon, D.; Gilkeson, R.; Michelotti, R.
1996-01-01
Rectangular Schlumberger arrays can be used for 2-dimensional lateral profiling of apparent resistivity at a unique current electrode separation, hence single depth of penetration. Numerous apparent resistivity measurements are collected moving the potential electrodes (fixed MN spacing) within a rectangle of defined dimensions. The method provides a fast, cost-effective means for the collection of dense resistivity data to provide high-resolution information on subsurface hydrogeologic conditions. Several rectangular Schlumberger resistivity arrays were employed at Los Alamos National Laboratory (LANL) from 1989 through 1995 in an area adjacent to and downhill from an outfall pipe, septic tank, septic drainfield, and sump. Six rectangular arrays with 2 AB spacings were used to delineate lateral low resistivity anomalies that may be related to fractures that contain clay and/or vadose zone water. Duplicate arrays collected over a three year time period exhibited very good data repeatability. The properties of tritium make it an excellent groundwater tracer. Because tritium was present in discharged water from all of the anthropogenic sources in the vicinity it was used for this purpose. One major low resistivity anomaly correlates with relatively high tritium concentrations in the tuff. This was determined from borehole samples collected within and outside of the anomalous zone. The anomaly is interpreted to be due to fractures that contain clay from the soil profile. The clay was deposited in the fractures by aeolian processes and by surface water infiltration. The fractures likely served as a shallow vadose zone groundwater pathway
Directory of Open Access Journals (Sweden)
Huixing Li
2016-05-01
Full Text Available In order to investigate the characteristics of boiling heat transfer for hydrocarbon mixture refrigerant in plate-fin heat exchanger which is used in the petrochemical industry field, a model was established on boiling heat transfer in vertical rectangular channel. The simulated results were compared with the experimental data from literature. The results show that the deviation between the simulated results and experimental data is within ±15%. Meanwhile, the characteristic of boiling heat transfer was investigated in vertical rectangular minichannel of plate-fin heat exchanger. The results show that the boiling heat transfer coefficient increases with the increase in quality and mass flux and is slightly impacted by the heat flux. This is because that the main boiling mechanism is forced convective boiling while the contribution of nucleate boiling is slight. The correlation of Liu and Winterton is in good agreement with the simulation results. The deviation between correlation calculations and simulation results is mostly less than ±15%. These results will provide some constructive instructions for the understanding of saturated boiling mechanism in a vertical rectangular minichannel and the prediction of heat transfer performance in plate-fin heat exchanger.
Premature and stable critical heat flux for downward flow in a narrow rectangular channel
International Nuclear Information System (INIS)
Lee, Juhyung; Chang, Soon Heung; Jeong, Yong Hoon; Jo, Daeseong
2014-01-01
It has been recommended that RRs and MTRs be designed to have sufficient margins for CHF and the onset of FI as well, since unstable flow could leads to premature CHF under very low wall heat flux in comparison to stable CHF. Even the fact and previous studies, however, the understanding of relationship among FI, premature CHF and stable CHF is not sufficient to date. In this regards, subcooled flow boiling in a vertical rectangular channel was experimentally investigated to enhance the understanding of the CHF and the effect of the two-phase flow instability on it under low pressure conditions, especially for downward flow which was adopted for Jordan Research and Training Reactor (JRTR) and Kijang research reactor (KJRR) to achieve easier fuel and irradiation rig loading. In this study, CHF for downward flow of water under low pressure in narrow rectangular channel was experimentally investigated. For conditions such as downward flow, narrow rectangular channel and low pressure, it has been deduced from literature that flow instability could largely influence on triggering CHF at lower heat flux, i. e. premature CHF. Total 54 CHF data, which includes premature and stable data was obtained for various fluid conditions and system configurations including inlet stiffness. The upper and lower boundaries of CHF were newly proposed based on the experiment
International Nuclear Information System (INIS)
Biagi, L.A.; Berkner, K.H.; Ehlers, K.W.; Paterson, J.A.; Porter, J.R.
1979-11-01
The design and fabrication techniques for a large, rectangular magnetic bucket plasma source are described. This source is compatible with the accelerator structures for the TFTR and DIII neutral-beam systems
National Research Council Canada - National Science Library
Klunker, E
1952-01-01
The effect of a finite trailing-edge thickness on the pressure drag of rectangular and delta wings with truncated diamond-shaped airfoil sections with a given thickness ratio is studied for supersonic...
Yuan, Naichang; He, Jianguo; Yao, Demiao; Dai, Qin; Lin, Weigan
1995-06-01
Two types of coplanar transmission lines, rectangular microshield coplanar coupled lines (RMCCL) and coplanar coupled rectangular microshield lines (CCRML), are proposed for MMIC applications. These are developed from coplanar coupled lines (CCL) and coplanar coupled strip lines (CCS). Analytic formulas are presented for calculating the quasistatic TEM parameters of these coupled lines by means of exact conformal mapping techniques. Numerical results are also presented to illustrate the properties of these coplanar transmission lines.
Use of rectangular grid miniplates for fracture fixation at the mandibular angle.
Hochuli-Vieira, Eduardo; Ha, Thi Khanh Linh; Pereira-Filho, Valfrido Antonio; Landes, Constantin Alexander
2011-05-01
The aim of this study was to evaluate the clinical outcome of patients with mandibular angle fractures treated by intraoral access and a rectangular grid miniplate with 4 holes and stabilized with monocortical screws. This study included 45 patients with mandibular angle fractures from the Department of Oral and Maxillofacial Surgery São Paulo State University, Araraquara, Brazil, and from the Clinic of Oral and Maxillofacial Surgery at the University of Frankfurt, Germany. The 45 fractures of the mandibular angle were treated with a rectangular grid miniplate of a 2.0-mm system by an intraoral approach with monocortical screws. Clinical evaluations were postoperatively performed at 15 and 30 days and 3 and 6 months, and the complications encountered were recorded and treated. The infection rate was 4.44% (2 patients), and in 1 patient it was necessary to replace hardware. This patient also had a fracture of the left mandibular body; 3 patients (6.66%) had minor occlusal changes that have been resolved with small occlusal adjustments. Before surgery, 15 patients (33.33%) presented with hypoesthesia of the inferior alveolar nerve; 4 (8.88%) had this change until the last clinical control, at 6 months. The rectangular grid miniplate used in this study was stable for the treatment of simple mandibular angle fractures through intraoral access, with low complication rates, easy handling, and easy adjustment, with a low cost. Concomitant mandibular fracture may increase the rate of complications. This plate should be indicated in fractures with sufficient interfragmentary contact. Copyright © 2011 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.
One-dimensional acoustic standing waves in rectangular channels for flow cytometry.
Austin Suthanthiraraj, Pearlson P; Piyasena, Menake E; Woods, Travis A; Naivar, Mark A; Lόpez, Gabriel P; Graves, Steven W
2012-07-01
Flow cytometry has become a powerful analytical tool for applications ranging from blood diagnostics to high throughput screening of molecular assemblies on microsphere arrays. However, instrument size, expense, throughput, and consumable use limit its use in resource poor areas of the world, as a component in environmental monitoring, and for detection of very rare cell populations. For these reasons, new technologies to improve the size and cost-to-performance ratio of flow cytometry are required. One such technology is the use of acoustic standing waves that efficiently concentrate cells and particles to the center of flow channels for analysis. The simplest form of this method uses one-dimensional acoustic standing waves to focus particles in rectangular channels. We have developed one-dimensional acoustic focusing flow channels that can be fabricated in simple capillary devices or easily microfabricated using photolithography and deep reactive ion etching. Image and video analysis demonstrates that these channels precisely focus single flowing streams of particles and cells for traditional flow cytometry analysis. Additionally, use of standing waves with increasing harmonics and in parallel microfabricated channels is shown to effectively create many parallel focused streams. Furthermore, we present the fabrication of an inexpensive optical platform for flow cytometry in rectangular channels and use of the system to provide precise analysis. The simplicity and low-cost of the acoustic focusing devices developed here promise to be effective for flow cytometers that have reduced size, cost, and consumable use. Finally, the straightforward path to parallel flow streams using one-dimensional multinode acoustic focusing, indicates that simple acoustic focusing in rectangular channels may also have a prominent role in high-throughput flow cytometry. Copyright © 2012 Elsevier Inc. All rights reserved.
Modeling the interference of vortex-induced vibration and galloping for a slender rectangular prism
Mannini, Claudio; Massai, Tommaso; Marra, Antonino Maria
2018-04-01
Several bluff bodies in an airflow, such as rectangular cylinders with moderate side ratio, in particular conditions of mass and damping can experience the interference of vortex-induced vibration (VIV) and galloping. This promotes a combined instability, which one may call "unsteady galloping", with peculiar features and possibly large vibration amplitudes in flow speed ranges where no excitation is predicted by classical theories. The mathematical model proposed between the 70's and the 80's by Prof. Y. Tamura to simulate this phenomenon was considered here for the case study of a two-dimensional rectangular cylinder with a side ratio of 1.5, having the shorter section side perpendicular to the smooth airflow. This wake-oscillator model relies on the linear superposition of the unsteady wake force producing VIV excitation and the quasi-steady force that is responsible for galloping. The model formulation was slightly modified, and the way to determine a crucial parameter was changed, revealing a previously unexplored behavior of the equations. In the present form, the model is able to predict the dynamic response of the rectangular cylinder with a satisfactory qualitative and, to a certain extent, quantitative agreement with the experimental data, although the limitations of the present approach are clearly highlighted in the paper. The mathematical modeling of unsteady galloping and the analysis of the results offer a deep insight into this complicated phenomenon and its nonlinear features. The model also represents a useful engineering tool to estimate the vibration of a structure or structural element for which the interference of VIV and galloping is envisaged.
Polydisperse particle-driven gravity currents in non-rectangular cross section channels
Zemach, T.
2018-01-01
We consider a high-Reynolds-number gravity current generated by polydisperse suspension of n types of particles distributed in a fluid of density ρi. Each class of particles in suspension has a different settling velocity. The current propagates along a channel of non-rectangular cross section into an ambient fluid of constant density ρa. The bottom and top of the channel are at z = 0, H, and the cross section is given by the quite general form -f1(z) ≤ y ≤ f2(z) for 0 ≤ z ≤ H. The flow is modeled by the one-layer shallow-water equations obtained for the time-dependent motion. We solve the problem by a finite-difference numerical code to present typical height h, velocity u, and mass fractions of particle (concentrations) (ϕ( j), j = 1, …, n) profiles. The runout length of suspensions in channels of power-law cross sections is analytically predicted using a simplified depth-averaged "box" model. We demonstrate that any degree of polydispersivity adds to the runout length of the currents, relative to that of equivalent monodisperse currents with an average settling velocity. The theoretical predictions are supported by the available experimental data. The present approach is a significant generalization of the particle-driven gravity current problem: on the one hand, now the monodisperse current in non-rectangular channels is a particular case of n = 1. On the other hand, the classical formulation of polydisperse currents for a rectangular channel is now just a particular case, f(z) = const., in the wide domain of cross sections covered by this new model.
Shirai, Atsushi; Masuda, Sunao
2013-01-01
The authors have previously presented a mathematical model to predict transit time of a neutrophil through an alveolar capillary segment which was modeled as an axisymmetric arc-shaped constriction settled in a cylindrical straight pipe to investigate the influence of entrance curvature of a capillary on passage of the cell. The axially asymmetric cross section of a capillary also influences the transit time because it requires three-dimensional deformation of a cell when it passes through the capillary and could lead to plasma leakage between the cell surface and the capillary wall. In this study, a rectangular channel was introduced, the side walls of which were moderately constricted, as a representative of axially asymmetric capillaries. Dependence of transit time of a neutrophil passing through the constriction on the constriction geometry, i.e., channel height, throat width and curvature radius of the constriction, was numerically investigated, the transit time being compared with that through the axisymmetric model. It was found that the transit time is dominated by the throat hydraulic diameter and curvature radius of the constriction and that the throat aspect ratio little affects the transit time with a certain limitation, indicating that if an appropriate curvature radius is chosen, such a rectangular channel model can be substituted for an axisymmetric capillary model having the same throat hydraulic diameter in terms of the transit time by choosing an appropriate curvature radius. Thus, microchannels fabricated by the photolithography technique, whose cross section is generally rectangular, are expected to be applicable to in vitro model experiments of neutrophil retention and passage in the alveolar capillaries. PMID:23527190
Critical heat flux for free convection boiling in thin rectangular channels
International Nuclear Information System (INIS)
Cheng, Lap Y.; Tichler, P.R.
1991-01-01
A review of the experimental data on free convection boiling critical heat flux (CHF) in vertical rectangular channels reveals three mechanisms of burnout. They are the pool boiling limit, the circulation limit, and the flooding limit associated with a transition in flow regime from churn to annular flow. The dominance of a particular mechanism depends on the dimensions of the channel. Analytical models were developed for each free convection boiling limit. Limited agreement with data is observed. A CHF correlation, which is valid for a wide range of gap sizes, was constructed from the CHFs calculated according to the three mechanisms of burnout. 17 refs., 7 figs
DEFF Research Database (Denmark)
Celestinos, Adrian; Nielsen, Sofus Birkedal
2006-01-01
an enhancement system with extra loudspeakers the sound pressure level distribution along the listening area presents a significant improvement in the subwoofer frequency range. The system is simulated and implemented on the three different rooms and finally verified by measurements on the real rooms.......Rectangular rooms have strong influence on the low frequency performance of loudspeakers. Simulations of three different room sizes have been carried out using finite-difference time-domain method (FDTD) in order to predict the behaviour of the sound field at low frequencies. By using...
Vector rectangular-shape laser based on reduced graphene oxide interacting with a long fiber taper.
Gao, Lei; Zhu, Tao; Huang, Wei; Zeng, Jing
2014-10-01
A vector dual-wavelength rectangular-shape laser (RSL) based on a long fiber taper deposited with reduced graphene oxide is proposed, where nonlinearity is enhanced due to a large evanescent-field-interacting length and strong field confinement of an 8 mm fiber taper with a waist diameter of 4 μm. Graphene flakes are deposited uniformly on the taper waist with light pressure effect, so this structure guarantees both excellent saturable absorption and high nonlinearity. The RSL with a repetition rate of 7.9 MHz shows fast polarization switching in two orthogonal polarization directions, and temporal and spectral characteristics are investigated.
Finite element analysis of crack growth from rectangular notch in mixed mode loading
International Nuclear Information System (INIS)
Mohd Rawi Mohd Zin
2002-01-01
The direction of crack growth from rectangular notch for ductile material is determined in this paper. The ductile material is assumed to exhibit the elastic-plastic behaviour. In the model, the crack is assumed to start when the J-integral fracture criterion exceeded the critical value during the application of load and the crack tip propagated to a priori. The direction of the crack is characterised by maximum principles stress criterion and the mechanism of crack propagation is simulated by deleted element technique. The model is validated with experimental results and it shows good agreement. (Author)
Experimental study on downward two-phase flow in narrow rectangular channel
Energy Technology Data Exchange (ETDEWEB)
Kim, T.H.; Jeong, J.H. [Pusan National Univ., Busan (Korea, Republic of)
2014-07-01
Adiabatic vertical two-phase flow of air and water through narrow rectangular channels was investigated. This study involved the observation of flow using a high speed camera and flow regimes were determined by image processing program using a MATLAB. The flows regimes in channel with downward flow are similar to those found by previous studies with upward flow. The flow regimes in downward flow at low liquid velocity are different from the previous studies in upward flow. The flow regimes can be classified into bubbly, cap-bubbly, slug and churn flow. (author)
Oscillating-flow loss test results in rectangular heat exchanger passages
Wood, J. Gary
1991-01-01
Test results of oscillating flow losses in rectangular heat exchanger passages of various aspect ratios are given. This work was performed in support of the design of a free-piston Stirling engine (FPSE) for a dynamic space power conversion system. Oscillating flow loss testing was performed using an oscillating flow rig, which was based on a variable stroke and variable frequency linear drive motor. Tests were run over a range of oscillating flow parameters encompassing the flow regimes of the proposed engine design. Test results are presented in both tabular and graphical form and are compared against analytical predictions.
Energy Technology Data Exchange (ETDEWEB)
Reddy, J N; Chao, W C [Virginia Polytechnic Inst. and State Univ., Blacksburg (USA). Dept. of Engineering Science and Mechanics
1981-04-01
In this study the effects of reduced integration, mesh size, and element type (i.e. linear or quadratic) on the accuracy of a penalty-finite element based on the theory governing thick, laminated, anisotropic composite plates are investigated. In order to assess the accuracy of the present finite element, exact closed-form solutions are developed for cross-ply and antisymmetric angle-ply rectangular plates simply supported and subjected to sinusoidally distributed mechanical and/or thermal loadings, and free vibration.
International Nuclear Information System (INIS)
Su Jiqiang; Sun Zhongning; Fan Guangming; Wang Shiming
2013-01-01
The long stripe coherent structure of the turbulent boundary layer in a small- scale vertical rectangular channel was observed by using hydrogen bubble flow trace visualization technique. The statistical properties of the long stripe in the experimental channel boundary layer were compared with that in the smooth flat plate boundary layer. The pitch characteristics were explained by the formation mechanism of the long stripe. It was analyzed that how the change of y + affected the distribution of the long stripe. In addition, the frequency characteristics of the long stripe were also investigated, and the correlation of the long stripe frequency in such a flow channel was obtained. (authors)
Traffic of leukocytes in microfluidic channels with rectangular and rounded cross-sections.
Yang, Xiaoxi; Forouzan, Omid; Burns, Jennie M; Shevkoplyas, Sergey S
2011-10-07
Traffic of leukocytes in microvascular networks (particularly through arteriolar bifurcations and venular convergences) affects the dynamics of capillary blood flow, initiation of leukocyte adhesion during inflammation, and localization and development of atherosclerotic plaques in vivo. Recently, a growing research effort has been focused on fabricating microvascular networks comprising artificial vessels with more realistic, rounded cross-sections. This paper investigated the impact of the cross-sectional geometry of microchannels on the traffic of leukocytes flowing with human whole blood through a non-symmetrical bifurcation that consisted of a 50 μm mother channel bifurcating into 30 μm and 50 μm daughter branches. Two versions of the same bifurcation comprising microchannels with rectangular and rounded cross-sections were fabricated using conventional multi-layer photolithography to produce rectangular microchannles that were then rounded in situ using a recently developed method of liquid PDMS/air bubble injection. For microchannels with rounded cross-sections, about two-thirds of marginated leukocytes traveling along a path in the top plane of the bifurcation entered the smallest 30 μm daughter branch. This distribution was reversed in microchannels with rectangular cross-sections--the majority of leukocytes traveling along a similar path continued to follow the 50 μm microchannels after the bifurcation. This dramatic difference in the distribution of leukocyte traffic among the branches of the bifurcation can be explained by preferential margination of leukocytes towards the corners of the 50 μm mother microchannels with rectangular cross-sections, and by the additional hindrance to leukocyte entry created by the sharp transition from the 50 μm mother microchannel to the 30 μm daughter branch at the intersection. The results of this study suggest that the trajectories of marginated leukocytes passing through non-symmetrical bifurcations are
Energy Technology Data Exchange (ETDEWEB)
Gillman, Eric D., E-mail: eric.gillman.ctr@nrl.navy.mil [National Research Council Postdoctoral Associate at the U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Amatucci, W. E. [U.S. Naval Research Laboratory, Washington, DC 20375 (United States)
2014-06-15
These experiments utilize a linear hollow cathode to create a dense, rectangular plasma sheet to simulate the plasma layer surrounding vehicles traveling at hypersonic velocities within the Earth's atmosphere. Injection of fine dielectric microparticles significantly reduces the electron density and therefore lowers the electron plasma frequency by binding a significant portion of the bulk free electrons to the relatively massive microparticles. Measurements show that microwave transmission through this previously overly dense, impenetrable plasma layer increases with the injection of alumina microparticles approximately 60 μm in diameter. This method of electron depletion is a potential means of mitigating the radio communications blackout experienced by hypersonic vehicles.
LUGS, Stress Analysis, Flexibility Factors for Rectangular Attachment on Thin Shell
International Nuclear Information System (INIS)
Dodge, W.G.
1977-01-01
1 - Description of problem or function: LUGS calculates stresses, stress indices, and flexibility factors for a rectangular attachment on a cylindrical shell. 2 - Method of solution: The program implements Bijlaard's series solution to the thin-shell equations. 3 - Restrictions on the complexity of the problem: Caution is recommended in using the code for attachments on very thin shells that have large circumferential dimension and small longitudinal dimension (GAMMA.GE.80, BETA2.LE.0.05, and BETA1.GE.0.3) as series convergence and/or numeric problems seem to exist
Energy characteristics of the double slot in the narrow wall of a rectangular waveguide
Martynenko, S. A.
2005-01-01
Based on approximation of the half-wave field distribution in the slots, an expression is derived for internal mutual conductance of closely-spaced slots, which form a double inclined slot in the narrow wall of a rectangular waveguide. The narrow wall has cut-outs reaching the broad wall. With the use of the method of induced magnetomotive forces, a mathematical model is devised for calculating the energy characteristics of the double slot. The impact of angle of inclination of the slots, dim...
Linear theory of a dielectric-loaded rectangular Cerenkov maser with a sheet electron beam
International Nuclear Information System (INIS)
Chen Ye; Wan Xiao-Sheng; Zhao Ding; Liu Wen-Xin; Wang Yong
2012-01-01
A three-dimensional model of a dielectric-loaded rectangular Cerenkov maser with a sheet electron beam for the beam-wave interaction is proposed. Based on this model, the hybrid-mode dispersion equation is derived with the Borgnis potential function by using the field-matching method. Its approximate solution is obtained under the assumption of a dilute electron beam. By using the Ansoft high frequency structural simulator (HFSS) code, the electromagnetic field distribution in the interaction structure is given. Through numerical calculations, the effects of beam thickness, beam and dielectric-layer gap distance, beam voltage, and current density on the resonant growth rate are analysed in detail
Theory of the special Smith-Purcell radiation from a rectangular grating
Energy Technology Data Exchange (ETDEWEB)
Liu, Weihao, E-mail: liuwhao@ustc.edu.cn; He, Zhigang, E-mail: hezhg@ustc.edu.cn; Jia, Qika [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029 (China); Li, Weiwei [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029 (China); Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati, RM (Italy)
2015-12-15
The recently uncovered special Smith-Purcell radiation (S-SPR) from the rectangular grating has significantly higher intensity than the ordinary Smith-Purcell radiation (SPR). Its monochromaticity and directivity are also much better. Here we explored the mechanism of the S-SPR by applying the fundamental electromagnetic theory and simulations. We have confirmed that the S-SPR is exactly from the radiating eigen modes of the grating. Its frequency and direction are well correlated with the beam velocity and structure parameters, which indicates its promising applications in tunable wave generation and beam diagnostic.
Maina, J W; Kawana, F; Matsui, K
2017-01-01
In order to better understand the impact of increased loading on roads, studies on tyre-road interaction have gained prominence in recent years. Tyres form an essential interface between vehicles and road pavement surfaces. These are the only parts of the vehicle that are in contact with the road and transmit the vehicle loading to the road surface. The use of the Cartesian coordinate system is convenient in dealing with a uniform/non-uniform tyre load acting over a rectangular area, but few ...
Buckling Analysis of Rectangular Plates with Variable Thickness Resting on Elastic Foundation
International Nuclear Information System (INIS)
Viswanathan, K K; Aziz, Z A; Navaneethakrishnan, P V
2015-01-01
Buckling of rectangular plates of variable thickness resting in elastic foundation is analysed using a quintic spline approximation technique. The thickness of the plate varies in the direction of one edge and the variations are assumed to be linear, exponential and sinusoidal. The plate is subjected to in plane load of two opposite edges. The buckling load and the mode shapes of buckling are computed from the eigenvalue problem that arises. Detailed parametric studies are made with different boundary conditions and the results are presented through the diagram and discussed
A Green's function solution for a rectangular heat source on an infinite plate
International Nuclear Information System (INIS)
Bainbridge, B.L.
1989-01-01
The applications associated with a rectangular heat source on an infinite plate range from integrated circuits to thin film heat flux sensors on thin substrates. The particular problem from which the solution is developed concerns the use of a resistive strip for monitoring currents generated in circuits exposed to electromagnetic fields. The Green's function formulation is solved by using early and late time approximations for which analytical solutions can be derived. In this paper expressions are developed for three sets of boundary conditions and compared to the experimental performance of a physical device
Energy Technology Data Exchange (ETDEWEB)
Sasada, Ichiro, E-mail: sasada@ence.kyushu-u.ac.jp [Applied Science for Electronics and Materials, Kyushu University, Kasuga (Japan)
2014-05-07
A method to reduce ac conductive losses in a thin rectangular busbar made of copper is presented. The method is based on a technique, which makes the distribution of the ac current in the cross section of a busbar flatter. Edges of a thin busbar are covered with low permeability magnetic thin layers as caps. The magnetic cap makes the impedance experienced by the current flowing near the edge comparatively larger so that currents cannot get crowded near the edges of a busbar. This method is numerically verified.
International Nuclear Information System (INIS)
Bowen, James; Zhang, Zhibing; Adams, Michael J; Cheneler, David; Ward, Michael C L; Walliman, Dominic; Arkless, Stuart G
2010-01-01
A simple but effective method for estimating the spring constant of commercially available atomic force microscope (AFM) cantilevers is presented, based on estimating the cantilever thickness from knowledge of its length, width, resonant frequency and the presence or absence of an added mass, such as a colloid probe at the cantilever apex, or a thin film of deposited material. The spring constant of the cantilever can then be estimated using standard equations for cantilever beams. The results are compared to spring constant calibration measurements performed using reference cantilevers. Additionally, the effect of the deposition of Cr and Ti thin films onto rectangular Si cantilevers is investigated
Peristaltic Flow of Carreau Fluid in a Rectangular Duct through a Porous Medium
Directory of Open Access Journals (Sweden)
R. Ellahi
2012-01-01
Full Text Available We have examined the peristaltic flow of Carreau fluid in a rectangular channel through a porous medium. The governing equations of motion are simplified by applying the long wavelength and low Reynolds number approximations. The reduced highly nonlinear partial differential equations are solved jointly by homotopy perturbation and Eigen function expansion methods. The expression for pressure rise is computed numerically by evaluating the numerical integration. The physical features of pertinent parameters have been discussed by plotting graphs of velocity, pressure rise, pressure gradient, and stream functions.
Discharge coefficient of a rectangular sharp-edged broad-crested weir
Zachoval Zbyněk; Knéblová Michaela; Roušar Ladislav; Rumann Ján; Šulc Jan
2014-01-01
his paper is concerned with the determination of the relationship for the calculation of the discharge coefficient at free overflow over a rectangular sharp-edged broad-crested weir without lateral contraction. The determination was made on the basis of new measurement in a range of the relative thickness of the weir from 0.12 to 0.30 and newly in a large range of relative height of the weir extremely from 0.24 to 6.8 which greatly expands the application possibilities of low weirs. In additi...
Directory of Open Access Journals (Sweden)
Youngmin Bae
2016-08-01
Full Text Available In this study, laminar natural circulation and heat transfer in a tall rectangular enclosure with disconnected vertical partitions inside were investigated. Analytical expressions were developed to predict the circulation flow rate and the average Nusselt number in a partially partitioned enclosure with isothermal side walls at different temperatures and insulated top and bottom walls. The proposed formulas are then validated against numerical results for modified Rayleigh numbers of up to 106. The impacts of the governing parameters are also examined along with a discussion of the heat transfer regimes.
International Nuclear Information System (INIS)
Chernov, N.I.; Ososkov, G.A.; Russakovich, N.A.; Velev, G.
1989-01-01
The Shower Hodoscopic Detector (SHD) is an important part of the HYPERON detector, as well as many other up-to-date detectors. It is a calorimeter with rectangular cells. In the present paper we consider a model of the distribution of energy release in the SHD cells and propose analytical solution of the problem of fitting the model distribution to experimental data. The corresponding programme is included in the HYPERON software and allows one to raise the rate of the data processing 8-9 times with about 10% reliability increase. 8 refs.; 8 figs
Solution of the two- dimensional heat equation for a rectangular plate
Directory of Open Access Journals (Sweden)
Nurcan BAYKUŞ SAVAŞANERİL
2015-11-01
Full Text Available Laplace equation is a fundamental equation of applied mathematics. Important phenomena in engineering and physics, such as steady-state temperature distribution, electrostatic potential and fluid flow, are modeled by means of this equation. The Laplace equation which satisfies boundary values is known as the Dirichlet problem. The solutions to the Dirichlet problem form one of the most celebrated topics in the area of applied mathematics. In this study, a novel method is presented for the solution of two-dimensional heat equation for a rectangular plate. In this alternative method, the solution function of the problem is based on the Green function, and therefore on elliptic functions.
Numerical simulation of sloshing in rectangular tanks with OpenFOAM CFD Package
International Nuclear Information System (INIS)
Andreski, Filip; Markov, Zoran; Diebold, Louis; Gazzola, Thomas
2009-01-01
The aim of this paper is to simulate the sloshing phenomenon using OpenFOAM CFD software package. The present paper treats a 2D numerical simulation of a partially filled tank that is located on a LNG carrier. Experiments were done on a rectangular tank excited with different excitation periods and amplitudes and the pressure was measured at certain locations on the tank walls. The goal of this research is to compare the experimental data for the pressure with the pressure results obtained with the CFD software. It is shown that the obtained results match well with the experimental data.
The effect of thermal conductance of vertical walls on natural convection in a rectangular enclosure
International Nuclear Information System (INIS)
Kikuchi, Y.; Yoshino, A.; Taii, K.
2004-01-01
This paper deals with the experimental results of natural convective heat transfer in a rectangular water layer bounded by vertical walls of different thermal conductance. The vertical walls were made of copper or stainless steel. A minimum was observed in the horizontal distribution of temperature near the heating wall since a secondary reverse flow occurred outside the boundary layer. For copper case the experimental results of Nusselt number agreed well with calculations under an isothermal wall condition. For stainless steel case, however, the measured values were lower than the calculations since a three-dimensional effect appeared in convection due to non-uniformity in wall temperature. (author)
Wakefield accelerator with hybrid plasma-dielectric structure of rectangular cross-section
International Nuclear Information System (INIS)
Kiselev, V.A.; Linnik, A.F.; Mirnyj, V.I.; Onishchenko, I.N.; Uskov, V.V.
2010-01-01
Increase of wakefield intensity at its excitation by a long train of relativistic electron bunches in the rectangular dielectric structure when it is filled with plasma of resonant density was experimentally observed. The first portion of the bunches, produced by electron linac 'Almaz-2', ionizes gas at atmospheric pressure so that plasma frequency becomes equal to bunch repetition frequency and to the frequency of principal Eigen mode of the dielectric structure. Excitation enhancement at such resonant conditions is being studied taking into account the improvement of bunch train propagation in the transit channel caused by charge compensation with plasma and the electrodynamics change of the dielectric structure at filling with plasma.
Larmor precession and dwell time of a relativistic particle scattered by a rectangular quantum well
Li, Z J; Liang, J J; Liang, J Q
2003-01-01
The Larmor precession of a relativistic neutral spin particle in a uniform constant magnetic field confined to the region of a one-dimensional rectangular potential well is investigated. The spin precession serves as a clock to measure the time spent by a quantum particle dwelling at a potential well. With the help of a general spin coherent state it is explicitly shown that the spin precession time is equal to the dwell time in the first-order approximation of the infinitesimal field limit. The comparison of the time in a potential well with that in free space shows apparent superluminality.
Theory of the special Smith-Purcell radiation from a rectangular grating
International Nuclear Information System (INIS)
Liu, Weihao; He, Zhigang; Jia, Qika; Li, Weiwei
2015-01-01
The recently uncovered special Smith-Purcell radiation (S-SPR) from the rectangular grating has significantly higher intensity than the ordinary Smith-Purcell radiation (SPR). Its monochromaticity and directivity are also much better. Here we explored the mechanism of the S-SPR by applying the fundamental electromagnetic theory and simulations. We have confirmed that the S-SPR is exactly from the radiating eigen modes of the grating. Its frequency and direction are well correlated with the beam velocity and structure parameters, which indicates its promising applications in tunable wave generation and beam diagnostic
Numerical simulation of microwave pulse coupling into the rectangular cavity with aperture arrays
International Nuclear Information System (INIS)
Li Rui; Yang Yiming; Qian Baoliang
2008-01-01
In this paper, the finite-difference time-domain (FDTD) algorithm is employed to simulate microwave pulse coupling into the rectangular cavity with aperture arrays. In the case in which the long-side of the slot in aperture arrays is perpendicular to the incident electrical field, and the electrical distribution of each center of slot in the aperture arrays in the process of microwave pulse coupling into the rectangular cavity with aperture arrays is analyzed in detail. We find that the effect of field enhancement of the slot in the middle of all the slots which distribute in the direction parallel to the incident electrical field is minimum and increases in turn from the middle to both sides symmetrically. We also find that the effect of field enhancement of the slot in the middle of all the slots which distribute in the direction perpendicular to the incident electrical field is maximum and decreases in turn from the middle to both sides symmetrically. In the same time, we investigate the factors that influence the effect of field enhancement of the center of each slot and the coupling electrical distribution in the cavity, including the number of slots and the spacing between slots. (authors)
A novel compact low impedance Marx generator with quasi-rectangular pulse output
Liu, Hongwei; Jiang, Ping; Yuan, Jianqiang; Wang, Lingyun; Ma, Xun; Xie, Weiping
2018-04-01
In this paper, a novel low impedance compact Marx generator with near-square pulse output based on the Fourier theory is developed. Compared with the traditional Marx generator, capacitors with different capacity have been used. It can generate a high-voltage quasi-rectangular pulse with a width of 100 ns at low impedance load, and it also has high energy density and power density. The generator consists of 16 modules. Each module comprises an integrative single-ended plastic case capacitor with a nominal value of 54 nF, four ceramic capacitors with a nominal value of 1.5 nF, a gas switch, a charging inductor, a grounding inductor, and insulators which provide mechanical support for all elements. In the module, different discharge periods from different capacitors add to the main circuit to form a quasi-rectangular pulse. The design process of the generator is analyzed, and the test results are provided here. The generator achieved pulse output with a rise time of 32 ns, pulse width of 120 ns, flat-topped width (95%-95%) of 50 ns, voltage of 550 kV, and power of 20 GW.
Sadeghi, Arman
2018-03-01
Modeling of fluid flow in polyelectrolyte layer (PEL)-grafted microchannels is challenging due to their two-layer nature. Hence, the pertinent studies are limited only to circular and slit geometries for which matching the solutions for inside and outside the PEL is simple. In this paper, a simple variational-based approach is presented for the modeling of fully developed electroosmotic flow in PEL-grafted microchannels by which the whole fluidic area is considered as a single porous medium of variable properties. The model is capable of being applied to microchannels of a complex cross-sectional area. As an application of the method, it is applied to a rectangular microchannel of uniform PEL properties. It is shown that modeling a rectangular channel as a slit may lead to considerable overestimation of the mean velocity especially when both the PEL and electric double layer (EDL) are thick. It is also demonstrated that the mean velocity is an increasing function of the fixed charge density and PEL thickness and a decreasing function of the EDL thickness and PEL friction coefficient. The influence of the PEL thickness on the mean velocity, however, vanishes when both the PEL thickness and friction coefficient are sufficiently high.
Near field vorticity distributions from a sharp-edged rectangular jet
International Nuclear Information System (INIS)
Vouros, Alexandros P.; Panidis, Thrassos; Pollard, Andrew; Schwab, Rainer R.
2015-01-01
Highlights: • Axial mean vorticity equation terms are calculated from experimental data. • Appearance of ridges, dumbbell shape and saddleback velocity profiles is highlighted. • Explanations are provided using terms from the vorticity equation. - Abstract: Experimental results on the near field development of a free rectangular jet with aspect ratio 10 are presented. The jet issues from a sharp-edged orifice attached to a rectangular settling chamber at Re h ∼ 23,000, based on slot width, h. Measurements on cross plane grids were obtained with a two-component hot wire anemometry probe, which provided information on the three dimensional characteristics of the flow field. Two key features of this type of jet are mean axial velocity profiles presenting two off axis peaks, commonly mentioned as saddleback profiles, and a predominant dumbbell shape as described by, for example, a contour of the axial mean velocity. The saddleback shape is found to be significantly influenced by the vorticity distribution in the transverse plane of the jet, while the dumbbell is traced to two terms in the axial mean vorticity transport equation that diffuse fluid from the centre of the jet towards its periphery. At the farthest location where measurements were taken, 30 slot widths from the jet exit, the flow field resembles that of an axisymmetric jet
Wave-filter-based approach for generation of a quiet space in a rectangular cavity
Iwamoto, Hiroyuki; Tanaka, Nobuo; Sanada, Akira
2018-02-01
This paper is concerned with the generation of a quiet space in a rectangular cavity using active wave control methodology. It is the purpose of this paper to present the wave filtering method for a rectangular cavity using multiple microphones and its application to an adaptive feedforward control system. Firstly, the transfer matrix method is introduced for describing the wave dynamics of the sound field, and then feedforward control laws for eliminating transmitted waves is derived. Furthermore, some numerical simulations are conducted that show the best possible result of active wave control. This is followed by the derivation of the wave filtering equations that indicates the structure of the wave filter. It is clarified that the wave filter consists of three portions; modal group filter, rearrangement filter and wave decomposition filter. Next, from a numerical point of view, the accuracy of the wave decomposition filter which is expressed as a function of frequency is investigated using condition numbers. Finally, an experiment on the adaptive feedforward control system using the wave filter is carried out, demonstrating that a quiet space is generated in the target space by the proposed method.
Simplified Method for the Characterization of Rectangular Straw Bales (RSB) Thermal Conductivity
Conti, Leonardo; Goli, Giacomo; Monti, Massimo; Pellegrini, Paolo; Rossi, Giuseppe; Barbari, Matteo
2017-10-01
This research aims to design and implement tools and methods focused at the assessment of the thermal properties of full size Rectangular Straw Bales (RSB) of various nature and origin, because their thermal behaviour is one of the key topics in market development of sustainable building materials. As a first approach a method based on a Hot-Box in agreement with the ASTM C1363 - 11 standard was adopted. This method was found to be difficult for the accurate measurement of energy flows. Instead, a method based on a constant energy input was developed. With this approach the thermal conductivity of a Rectangular Straw-Bale (RSB λ) can be determined by knowing the thermal conductivity of the materials used to build the chamber and the internal and external temperature of the samples and of the chamber. A measurement a metering chamber was built and placed inside a climate chamber, maintained at constant temperature. A known quantity of energy was introduced inside the metering chamber. A series of thermopiles detects the temperature of the internal and external surfaces of the metering chamber and of the specimens allowing to calculate the thermal conductivity of RSB in its natural shape. Different cereal samples were tested. The values were found consistent with those published in scientific literature.
Discharge Coefficient of Rectangular Short-Crested Weir with Varying Slope Coefficients
Directory of Open Access Journals (Sweden)
Yuejun Chen
2018-02-01
Full Text Available Rectangular short-crested weirs are widely used for simple structure and high discharge capacity. As one of the most important and influential factors of discharge capacity, side slope can improve the hydraulic characteristics of weirs at special conditions. In order to systemically study the effects of upstream and downstream slope coefficients S1 and S2 on overflow discharge coefficient in a rectangular short-crested weir the Volume of Fluid (VOF method and the Renormalization Group (RNG κ-ε turbulence model are used. In this study, the slope coefficient ranges from V to 3H:1V and each model corresponds to five total energy heads of H0 ranging from 8.0 to 24.0 cm. Comparisons of discharge coefficients and free surface profiles between simulated and laboratory results display a good agreement. The simulated results show that the difference of discharge coefficients will decrease with upstream slopes and increase with downstream slopes as H0 increases. For a given H0, the discharge coefficient has a convex parabolic relation with S1 and a piecewise linearity relation with S2. The maximum discharge coefficient is always obtained at S2 = 0.8. There exists a difference between upstream and downstream slope coefficients in the influence range of free surface curvatures. Furthermore, a proposed discharge coefficient equation by nonlinear regression is a function of upstream and downstream slope coefficients.
Analytical Solution for 2D Inter-Well Porous Flow in a Rectangular Reservoir
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Junfeng Ding
2018-04-01
Full Text Available Inter-well fluid flows through porous media are commonly encountered in the production of groundwater, oil, and geothermal energy. In this paper, inter-well porous flow inside a rectangular reservoir is solved based on the complex variable function theory combined with the method of mirror images. In order to derive the solution analytically, the inter-well flow is modeled as a 2D flow in a homogenous and isotropic porous medium. The resulted exact analytical solution takes the form of an infinite series, but it can be truncated to give high accuracy approximation. In terms of nine cases of inter-well porous flow associated with enhanced geothermal systems, the applications of the obtained analytical solution are demonstrated, and the convergence properties of the truncated series are investigated. It is shown that the convergent rate of the truncated series increases with the symmetric level of well distribution inside the reservoir, and the adoption of Euler transform significantly accelerates the convergence of alternating series cases associated with asymmetric well distribution. In principle, the analytical solution proposed in this paper can be applied to other scientific and engineering fields, as long as the involved problem is governed by 2D Laplace equation in a rectangular domain and subject to similar source/sink and boundary conditions, i.e., isolated point sources/sinks and uniform Dirichlet or homogeneous Neumann boundary conditions.
The testing of the Rectangular Pivot-point bellows for the PPPL Tokamak fusion test reactor
International Nuclear Information System (INIS)
Haughian, J.; Fong, M.; Greer, J.; Lou, K.; Scalise, D.T.
1983-01-01
The Neutral Beam Pivot Point Bellows (PPB) is installed in the duct which connects the Neutral Beam Enclosure to the Torus. This bellows, located at the pivot point, must fit the severely limited space available at the pivot-point location. Consequently, it has to be made rectangular in cross section with a large inside area for beam access. This leads to small convolutions with high stress concentrations. The function of the bellows is to permit change in the angular positioning of the neutral beam line with respect to the Tokamak, to isolate the Neutral Beam Line from the deflection of the Torus during bake out, and to allow for all misalignments. Internally the bellows will have a vacuum along with such gases such as hydrogen or deuterium. Externally, air or nitrogen gas will be present. It is constructed of Inconel 718 convolutions welded together to provide a clear rectangular opening of 23.4 by 32.2 inches, joined to a 625 Inconel flange at each end
Spectral Optical Readout of Rectangular-Miniature Hollow Glass Tubing for Refractive Index Sensing.
Rigamonti, Giulia; Bello, Valentina; Merlo, Sabina
2018-02-16
For answering the growing demand of innovative micro-fluidic devices able to measure the refractive index of samples in extremely low volumes, this paper presents an overview of the performances of a micro-opto-fluidic sensing platform that employs rectangular, miniature hollow glass tubings. The operating principle is described by showing the analytical model of the tubing, obtained as superposition of different optical cavities, and the optical readout method based on spectral reflectivity detection. We have analyzed, in particular, the theoretical and experimental optical features of rectangular tubings with asymmetrical geometry, thus with channel depth larger than the thickness of the glass walls, though all of them in the range of a few tens of micrometers. The origins of the complex line-shape of the spectral response in reflection, due to the different cavities formed by the tubing flat walls and channel, have been investigated using a Fourier transform analysis. The implemented instrumental configuration, based on standard telecom fiberoptic components and a semiconductor broadband optical source emitting in the near infrared wavelength region centered at 1.55 µm, has allowed acquisition of reflectivity spectra for experimental verification of the expected theoretical behavior. We have achieved detection of refractive index variations related to the change of concentration of glucose-water solutions flowing through the tubing by monitoring the spectral shift of the optical resonances.
Combined Transverse Steel-External FRP Confinement Model for Rectangular Reinforced Concrete Columns
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Ahmed Al-Rahmani
2016-02-01
Full Text Available Recently, the need to increase the strength of reinforced concrete members has become a subject that civil engineers are interested in tackling. Of the many proposed solutions, fiber-reinforced polymer (FRP materials have attracted attention due to their superior properties, such as high strength-to-weight ratio, high energy absorption and excellent corrosion resistance. FRP wrapping of concrete columns is done to enhance the ultimate strength due to the confinement effect, which is normally induced by steel ties. The existence of the two confinement systems changes the nature of the problem, thus necessitating specialized nonlinear analysis to obtain the column’s ultimate capacity. Existing research focused on a single confinement system. Furthermore, very limited research on rectangular sections was found in the literature. In this work, a model to estimate the combined behavior of the two systems in rectangular columns is proposed. The calculation of the effective lateral pressure is based on the Lam and Teng model and the Mander model for FRP wraps and steel ties, respectively. The model then generates stress-strain diagrams for both the concrete core and the cover. The model was developed for the analysis in extreme load events, where all possible contributions to the column’s ultimate capacity should be accounted for without any margin of safety. The model was validated against experiments, and the results obtained showed good agreement with almost all of the available experimental data.
Energy Technology Data Exchange (ETDEWEB)
Kim, Sin-Yeob; Shin, Dong-Ho; Park, Goon-Cherl; Cho, Hyoung Kyu [Seoul National Univ., Seoul (Korea, Republic of); Kim, Chan-Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2016-10-15
VHTR being developed at Korea Atomic Energy Research Institute adopts an air-cooled Reactor Cavity Cooling System (RCCS) incorporating rectangular riser channels to remove the afterheat emitted from the reactor vessel. Because the performance of RCCS is determined by heat removal rate through the RCCS riser, it is important to understand the heat transfer phenomena in the RCCS riser to ensure the safety of the reactor. In the mixed convection, due to the buoyance force induced by temperature and density differences, local flow structure and heat transfer mode near the heated wall have significantly dissimilar characteristics from both forced convection and free convection. In this study, benchmark calculation was conducted to reproduce the previous statements that V2F turbulence model can capture the mixed convection phenomena with the Shehata's experimental data. Then, the necessity of the model validation for the mixed convection phenomena was confirmed with the CFD analyses for the geometry of the prototype RCCS riser. For the purpose of validating the turbulence models for mixed convection phenomena in the heated rectangular riser duct, validation plan with three experimental tests was introduced. Among them, the flow visualization test facility with preserved cross-section geometry was introduced and a preliminary test result was shown.
International Nuclear Information System (INIS)
Nur Rahmad Yusuf
2013-01-01
Experimental studies to study the mechanism of boiling heat transfer in narrow rectangular channel under severe accident scenarios of TMI-2 nuclear power plant necessary for the understanding of management-related accidents. The research aims to obtain heat flux values and the critical heat flux (CHF) during the process of boiling heat transfer in narrow rectangular channel. Research methods experimentally using the HEATING-02 test section with cooling fluid is water temperature 98 °C. Experiments performed by varying the hot plate initial temperature of 100 °C, 200 °C and 300 °C with channel size 1 mm. Boiling during the cooling process was recorded by a transient temperature on the hot plate. Temperature data used to calculate the heat flux and wall temperature, the results are represented through the boiling curve. The results show that the higher plate temperature, the narrower width of the curve will be narrower and its mean that the plate surface cooling time will be slower. Results visualization is seen that the CCF occurred at the hot plate initial temperature of 100 °C, 200 °C and 300 °C with channel size 1 mm. (author)
Su, Jinghong; Chen, Xiaodong; Hu, Guoqing
2018-03-01
Inertial migration has emerged as an efficient tool for manipulating both biological and engineered particles that commonly exist with non-spherical shapes in microfluidic devices. There have been numerous studies on the inertial migration of spherical particles, whereas the non-spherical particles are still largely unexplored. Here, we conduct three-dimensional direct numerical simulations to study the inertial migration of rigid cylindrical particles in rectangular microchannels with different width/height ratios under the channel Reynolds numbers (Re) varying from 50 to 400. Cylindrical particles with different length/diameter ratios and blockage ratios are also concerned. Distributions of surface force with the change of rotation angle show that surface stresses acting on the particle end near the wall are the major contributors to the particle rotation. We obtain lift forces experienced by cylindrical particles at different lateral positions on cross sections of two types of microchannels at various Re. It is found that there are always four stable equilibrium positions on the cross section of a square channel, while the stable positions are two or four in a rectangular channel, depending on Re. By comparing the equilibrium positions of cylindrical particles and spherical particles, we demonstrate that the equivalent diameter of cylindrical particles monotonously increases with Re. Our work indicates the influence of a non-spherical shape on the inertial migration and can be useful for the precise manipulation of non-spherical particles.
Effects of anisotropic properties on bursting behavior of rectangular cup with a V-notch
Energy Technology Data Exchange (ETDEWEB)
Kim, Jeong Tai [R and D Center, TERA Co. Ltd., Seoul (Korea, Republic of); Kim, Sang Mok [R and D Center, Hyosung Power and Industrial Systems PG, Changwon (Korea, Republic of); Kang, Beom Soo [Dept. of Aerospace Engineering, Pusan National University, Busan (Korea, Republic of); Ku, Tae Wan [Engineering Research Center of Innovative Technology on Advanced Forming, Pusan National University, Busan (Korea, Republic of)
2016-09-15
Effects of mechanical anisotropic properties on bursting failure and its pressure of rectangular deep-drawn cup fabricated by using AA3005-H14 thin sheet are investigated to utilize for electrolyte container of lithium-ion secondary batteries. The V-notch shape with a depth of 0.1 mm and an angle of 20.0 degrees is defined on the rectangular cup, which has a thickness of 0.20 mm on the major surface and that of 0.30 mm on the minor surface. With the measured mechanical properties by uni-axial tensile tests and the defined V-notch geometry, a series of numerical prediction models considering isotropic, planar and normal anisotropic characteristics, are built-up and the bursting simulations are performed. Thereafter, the bursting fracture behavior is investigated by adopting ductile fracture criterion proposed by Cockcroft and Latham. The results predicted for the planar and the normal anisotropic models show that the bursting fracture pressure is well matched to 0.400 MPa, and the isotropic and the planar anisotropic models present a bursting fracture height of about 4.95 mm and 4.92 mm, respectively. A series of experimental investigations are undertaken to verify the bursting deformation that had been predicted. The bursting pressure and its height during experimental verifications are shown to be in good agreement with each variation of about 5.88% and roughly 0.20% with respect to the numerical results obtained using the planar anisotropic model.
Fully developed liquid-metal flow in multiple rectangular ducts in a strong uniform magnetic field
International Nuclear Information System (INIS)
Molokov, S.
1993-01-01
Fully developed liquid-metal flow in a straight rectangular duct with thin conducting walls is investigated. The duct is divided into a number of rectangular channels by electrically conducting dividing walls. A strong uniform magnetic field is applied parallel to the outer side walls and dividing walls and perpendicular to the top and the bottom walls. The analysis of the flow is performed by means of matched asymptotics at large values of the Hartmann number M. The asymptotic solution obtained is valid for arbitrary wall conductance ratio of the side walls and dividing walls, provided the top and bottom walls are much better conductors than the Hartmann layers. The influence of the Hartmann number, wall conductance ratio, number of channels and duct geometry on pressure losses and flow distribution is investigated. If the Hartmann number is high, the volume flux is carried by the core, occupying the bulk of the fluid and by thin layers with thickness of order M -1/2 . In some of the layers, however, the flow is reversed. As the number of channels increases the flow in the channels close to the centre approaches a Hartmann-type flow with no jets at the side walls. Estimation of pressure-drop increase in radial ducts of a self-cooled liquid-metal blanket with respect to flow in a single duct with walls of the same wall conductance ratio gives an upper limit of 30%. (author). 13 refs., 10 figs., 1 tab
Experimental study of falling film evaporation in large scale rectangular channel
International Nuclear Information System (INIS)
Huang, X.G.; Yang, Y.H.; Hu, P.
2015-01-01
Highlights: • This paper studies the falling film evaporation in large scale rectangular channel experimentally. • The effects of air flow rate, film temperature and film flow rate on falling film evaporation are analyzed. • Increasing the air flow rate is considered as an efficient method to enhance the evaporation rate. • A correlation including the wave effect for falling film evaporation is derived based on heat and mass transfer analogy. - Abstract: The falling film evaporation in a large scale rectangular channel is experimentally studied in this paper for the design and improvement of passive containment cooling system. The evaporation mass transfer coefficient h D is obtained by the evaporation rate and vapor partial pressure difference of film surface and air bulk. The experimental results indicate that increasing of air flow rate appears to enhance h D , while the film temperature and film flow rate have little effect on h D . Since the wave effect on evaporation is noticed in experiment, the evaporation mass transfer correlation including the wave effect is developed on the basis of heat and mass transfer analogy and experimental data
Conversion of output factor from square field into rectangular field in electron beam
Wang Jian Hua; Xu Yi Fei
2002-01-01
Objective: A simple and accurate calculation method was designed to convert output factor from square field into rectangular field in electron beam, which can be easily implemented in clinical practice. Methods: 6, 12, 15 MeV electron beam, field size 6.0 cm x 7.5 cm, 5.0 cm x 10.0 cm, 6.0 cm x 12.0 cm, TL3000C dosimeter and source-to-surface distance method were used in dose measurement. The measured dose values were compared with the calculated ones from three theoretical equations with the conformation evaluated. Results: The calculated dose values from three theoretical equations differed from the measured ones by 0.23%, 1.30% and 1.10% (6 MeV), 0.63%, 0.90% and 0.73% (12 MeV), 0.50%, 1.80% and 3.40% (15 MeV), conforming best to the equation OUF (X, Y)=[OUF(X,X). OUF(Y,Y)] sup 1 sup / sup 2. When the size of the field was longer than Rp, the difference between the calculated values and measured ones was relatively very small. Conclusions: The output factor in rectangular fields can be accurately calculate...
Evaluation of the ultimate pressure capacity of rectangular HVAC ducts for nuclear pwoer plants
International Nuclear Information System (INIS)
Wedellsborg, B.W.
1984-01-01
Typical Category I HVAC ducts in a nuclear plant must be designed for loads and load combinations including positive and negative pressure loads which are generated due to the normal operation and postulated accident conditions. These pressure loads most often govern the design of the HVAC ducts. Structural design criteria are presently based on the AISI Code which limits the duct panel width-to-thickness ratio to a maximum of 500 and the maximum height-to-thickness ratio to 200, unless it can be shown by structural tests that larger ratios can be used. Test Programs performed on rectangular HVAC ducts subjected to vacumm loads have substantiated the use of ducts having panel width to thickness ratios of up to 1600. The results of the test programs were subsequently incorporated into the design through a more rational analytical design method which was developed from and correlates well with the test results. The purpose of this paper is to present the analytical design method and its correlation with the test results. Simple formulae for the design of rectangular HVAC ducts are presented. Lower bound values of duct sheet, and stiffener ultimate loads are derived, and correlated with recent test results. Analytically predicted ultimate pressures are also compared with other available duct test data
Directory of Open Access Journals (Sweden)
Kalyani Bhide
2018-03-01
Full Text Available The aim of this work is to highlight the significance of Fluid–Thermal–Structural Interaction (FTSI as a diagnosis of existing designs, and as a means of preliminary investigation to ensure the feasibility of new designs before conducting experimental and field tests. The novelty of this work lies in the multi-physics simulations, which are, for the first time, performed on rectangular nozzles. An existing experimental supersonic rectangular converging/diverging nozzle geometry is considered for multi-physics 3D simulations. A design that has been improved by eliminating the sharp throat is further investigated to evaluate its structural integrity at design Nozzle Pressure Ratio (NPR 3.67 and off-design (NPR 4.5 conditions. Static structural analysis is performed by unidirectional coupling of pressure loads from steady 3D Computational Fluid Dynamics (CFD and thermal loads from steady thermal conduction simulations, such that the simulations represent the experimental set up. Structural deformation in the existing design is far less than the boundary layer thickness, because the impact of Shock wave Boundary Layer Interaction (SBLI is not as severe. FTSI demonstrates that the discharge coefficient of the improved design is 0.99, and its structural integrity remains intact at off-design conditions. This proves the feasibility of the improved design. Although FTSI influence is shown for a nozzle, the approach can be applied to any product design cycle, or as a prelude to building prototypes.
Energy Technology Data Exchange (ETDEWEB)
Teamah, M.A. [Faculty of Engineering, Alexandria University, Mech. Eng. Dept, Alexandria (Egypt); El-Maghlany, W.M. [Faculty of Engineering, Suez Canal University, Ismailia (Egypt)
2010-09-15
The present study is concerned with the mixed convection in a rectangular lid-driven cavity under the combined buoyancy effects of thermal and mass diffusion. Double-diffusive convective flow in a rectangular enclosure with moving upper surface is studied numerically. Both upper and lower surfaces are being insulated and impermeable. Constant different temperatures and concentration are imposed along the vertical walls of the enclosure, steady state laminar regime is considered. The transport equations for continuity, momentum, energy and spices transfer are solved. The numerical results are reported for the effect of Richardson number, Lewis number, and buoyancy ratio on the iso-contours of stream line, temperature, and concentration. In addition, the predicted results for both local and average Nusselt and Sherwood numbers are presented and discussed for various parametric conditions. This study was done for 0.1 <= Le <= 50 and Prandtl number Pr = 0.7. Through out the study the Grashof number and aspect ratio are kept constant at 10{sup 4} and 2 respectively and -10 <= N <= 10, while Richardson number has been varied from 0.01 to 10 to simulate forced convection dominated flow, mixed convection and natural convection dominated flow. (authors)
Parametrisation of the collimator scatter correction factors of square and rectangular photon beams
International Nuclear Information System (INIS)
Jager, H.N.; Heukelom, S.; Kleffens, H.J. van; Gasteren, J.J.M. van; Laarse, R. van der; Venselaar, J.L.M.; Westermann, C.F.
1995-01-01
Collimator scatter correction factors S c have been measured with a cylindrical mini-phantom for five types of dual photon energy accelerators with energies between 6 and 25 MV. Using these S c -data three methods to parametrize S c of square fields have been compared including a third-order polynomial of the natural logarithm of the fieldsize normalised by the fieldsize of 10 cm 2 . Also six methods to calculate S c of rectangular fields have been compared including a new one which determines the equivalent fieldsize by extending Sterling's method. The deviation between measured and calculated S c for every accelerator, energy and all methods are determined resulting in the maximum and average deviation per method. Applied to square fields the maximum and average deviation were for the method of Chen 0.64% and 0.15%, of Szymzcyk 0.98% and 0.21%, and of this work 0.41% and 0.10%. For the rectangular fields the deviations were for the method of Sterling 1.89% and 0.50%, of Vadash 1.60% and 0.28%, of Szymczyk et al. 1.21% and 0.25%, of Chen 1.84% and 0.31% and of this work 0.79% and 0.20%. Finally, a recommendation is given how to limit the number of fields at which S c should be measured
Phase distribution measurements in narrow rectangular channels using image processing techniques
International Nuclear Information System (INIS)
Bentley, C.; Ruggles, A.
1991-01-01
Many high flux research reactor fuel assemblies are cooled by systems of parallel narrow rectangular channels. The HFIR is cooled by single phase forced convection under normal operating conditions. However, two-phase forced convection or two phase mixed convection can occur in the fueled region as a result of some hypothetical accidents. Such flow conditions would occur only at decay power levels. The system pressure would be around 0.15 MPa in such circumstances. Phase distribution of air-water flow in a narrow rectangular channel is examined using image processing techniques. Ink is added to the water and clear channel walls are used to allow high speed still photographs and video tape to be taken of the air-water flow field. Flow field images are digitized and stored in a Macintosh 2ci computer using a frame grabber board. Local grey levels are related to liquid thickness in the flow channel using a calibration fixture. Image processing shareware is used to calculate the spatially averaged liquid thickness from the image of the flow field. Time averaged spatial liquid distributions are calculated using image calculation algorithms. The spatially averaged liquid distribution is calculated from the time averaged spatial liquid distribution to formulate the combined temporally and spatially averaged fraction values. The temporally and spatially averaged liquid fractions measured using this technique compare well to those predicted from pressure gradient measurements at zero superficial liquid velocity
Springback Mechanism Analysis and Experiments on Robotic Bending of Rectangular Orthodontic Archwire
Jiang, Jin-Gang; Han, Ying-Shuai; Zhang, Yong-De; Liu, Yan-Jv; Wang, Zhao; Liu, Yi
2017-11-01
Fixed-appliance technology is the most common and effective malocclusion orthodontic treatment method, and its key step is the bending of orthodontic archwire. The springback of archwire did not consider the movement of the stress-strain-neutral layer. To solve this problem, a springback calculation model for rectangular orthodontic archwire is proposed. A bending springback experiment is conducted using an orthodontic archwire bending springback measurement device. The springback experimental results show that the theoretical calculation results using the proposed model coincide better with the experimental testing results than when movement of the stress-strain-neutral layer was not considered. A bending experiment with rectangular orthodontic archwire is conducted using a robotic orthodontic archwire bending system. The patient expriment result show that the maximum and minimum error ratios of formed orthodontic archwire parameters are 22.46% and 10.23% without considering springback and are decreased to 11.35% and 6.13% using the proposed model. The proposed springback calculation model, which considers the movement of the stress-strain-neutral layer, greatly improves the orthodontic archwire bending precision.
An analytical solution for Dean flow in curved ducts with rectangular cross section
Norouzi, M.; Biglari, N.
2013-05-01
In this paper, a full analytical solution for incompressible flow inside the curved ducts with rectangular cross-section is presented for the first time. The perturbation method is applied to solve the governing equations and curvature ratio is considered as the perturbation parameter. The previous perturbation solutions are usually restricted to the flow in curved circular or annular pipes related to the overly complex form of solutions or singularity situation for flow in curved ducts with non-circular shapes of cross section. This issue specifies the importance of analytical studies in the field of Dean flow inside the non-circular ducts. In this study, the main flow velocity, stream function of lateral velocities (secondary flows), and flow resistance ratio in rectangular curved ducts are obtained analytically. The effect of duct curvature and aspect ratio on flow field is investigated as well. Moreover, it is important to mention that the current analytical solution is able to simulate the Taylor-Görtler and Dean vortices (vortices in stable and unstable situations) in curved channels.
Effect of the configuration of the corner in a narrow rectangular channel on flow and heat transfer
International Nuclear Information System (INIS)
Xu Jianjun; Chen Bingde; Wang Xiaojun
2009-01-01
In order to further understand the effect of the configuration of the corner in a narrow rectangular channel on flow and heat transfer, flow field and temperature field in a narrow rectangular channel were numerical simulated by using CFD code CFX10.0. The results show under the condition of equal quantity of heat of solid which is obtained by decreasing the solid of the corner, the distributions of inside wall temperature for the orthogonal and circular type configurations of the corner are almost the same as that of the archetypal configuration, and those can simulate heat transfer of the archetypal con- figuration. Under the condition of equal Re, secondary flow and friction pressure of the orthogonal type configuration are almost the same as those of the circular type configuration, which shows that the circular type configuration of the corner in a narrow channel can substituted for the archetypal configuration to simulate flow and heat transfer in a narrow rectangular channel. (authors)
International Nuclear Information System (INIS)
Li Changwei; Cao Xiaxin; Sun Licheng; Jin Guangyuan
2013-01-01
Based on the data of two-phase flow in narrow rectangular channel, the influence of the two-phase flow friction characteristic under the different fluctuant states was analyzed. Through analyzing the experimental data, it is shown that the fluctuant amplitude of the friction pressure drop is affected slightly by the fluctuant period in narrow rectangular channel, but the frequency of the friction pressure drop fluctuation is changed. However, the change of fluctuant period is of little effect on the average frictional pressure drop. Comparing the φ l 2 (φ g 2 )-X variation curves at static condition with the ones at fluctuant condition, using the L-M method, it's found that the two phase frictional pressure drop in the narrow rectangular channel under the fluctuant state can be calculated by the φ l 2 (φ g 2 )-X variation curve at static condition. (authors)
Zhai, Xiaofang; Zhu, Xinyan; Xiao, Zhifeng; Weng, Jie
2009-10-01
Historically, cellular automata (CA) is a discrete dynamical mathematical structure defined on spatial grid. Research on cellular automata system (CAS) has focused on rule sets and initial condition and has not discussed its adjacency. Thus, the main focus of our study is the effect of adjacency on CA behavior. This paper is to compare rectangular grids with hexagonal grids on their characteristics, strengths and weaknesses. They have great influence on modeling effects and other applications including the role of nearest neighborhood in experimental design. Our researches present that rectangular and hexagonal grids have different characteristics. They are adapted to distinct aspects, and the regular rectangular or square grid is used more often than the hexagonal grid. But their relative merits have not been widely discussed. The rectangular grid is generally preferred because of its symmetry, especially in orthogonal co-ordinate system and the frequent use of raster from Geographic Information System (GIS). However, in terms of complex terrain, uncertain and multidirectional region, we have preferred hexagonal grids and methods to facilitate and simplify the problem. Hexagonal grids can overcome directional warp and have some unique characteristics. For example, hexagonal grids have a simpler and more symmetric nearest neighborhood, which avoids the ambiguities of the rectangular grids. Movement paths or connectivity, the most compact arrangement of pixels, make hexagonal appear great dominance in the process of modeling and analysis. The selection of an appropriate grid should be based on the requirements and objectives of the application. We use rectangular and hexagonal grids respectively for developing city model. At the same time we make use of remote sensing images and acquire 2002 and 2005 land state of Wuhan. On the base of city land state in 2002, we make use of CA to simulate reasonable form of city in 2005. Hereby, these results provide a proof of
Rusterholz, Thomas; Achermann, Peter; Dürr, Roland; Koenig, Thomas; Tarokh, Leila
2017-06-01
Investigating functional connectivity between brain networks has become an area of interest in neuroscience. Several methods for investigating connectivity have recently been developed, however, these techniques need to be applied with care. We demonstrate that global field synchronization (GFS), a global measure of phase alignment in the EEG as a function of frequency, must be applied considering signal processing principles in order to yield valid results. Multichannel EEG (27 derivations) was analyzed for GFS based on the complex spectrum derived by the fast Fourier transform (FFT). We examined the effect of window functions on GFS, in particular of non-rectangular windows. Applying a rectangular window when calculating the FFT revealed high GFS values for high frequencies (>15Hz) that were highly correlated (r=0.9) with spectral power in the lower frequency range (0.75-4.5Hz) and tracked the depth of sleep. This turned out to be spurious synchronization. With a non-rectangular window (Tukey or Hanning window) these high frequency synchronization vanished. Both, GFS and power density spectra significantly differed for rectangular and non-rectangular windows. Previous papers using GFS typically did not specify the applied window and may have used a rectangular window function. However, the demonstrated impact of the window function raises the question of the validity of some previous findings at higher frequencies. We demonstrated that it is crucial to apply an appropriate window function for determining synchronization measures based on a spectral approach to avoid spurious synchronization in the beta/gamma range. Copyright © 2017 Elsevier B.V. All rights reserved.
New Triangular and Rectangular NAM Representation Algorithm for Color Images%一种新的TRNAM彩色图像表示算法
Institute of Scientific and Technical Information of China (English)
郑运平
2011-01-01
The Non-symmetry and Anti-packing Model (NAM) is suitable for representations of image pattern, audio pattern, video pattern, and text pattern, and it is a general pattern representation model. Inspired by the idea of representing the pixels by the Gray code, a new triangular and rectangular NAM representation algorithm for color images, which is called the NTRNAM algorithm, is proposed. The principium and the description of the NTRNAM algorithm are presented and the storage structure, the total data a-mount, and the time and space complexities of the proposed algorithm are analyzed. The theoretical and experimental results show that the NTRNAM algorithm can greatly reduce the number of subpatterns and simultaneously save the storage room, and therefore it is an effective algorithm for color image representation.%非对称逆布局模型(NAM)适用于图像模式、语音模式、文本模式、视频模式的表示,是一个通用型的模式表示模型.借助于格雷码表示图像像素的思想,提出了一种新的三角形和矩形NAM彩色图像表示算法(简称NTRNAM算法).给出了算法的原理及形式化描述,并对其存储结构、总数据量和时空复杂性进行了分析.理论分析和实验结果表明:NTRNAM算法能够显著降低子模式数和存储空间,是一种有效的彩色图像表示算法.
Impact of different rectangular wires on torsional expression of different sizes of buccal tube.
Ajami, Shabnam; Boroujeni, Afshar-Rasti
2018-01-01
Torsions in rectangular wires are the essential part of corrections in the finishing stage of treatment. Moreover the greatest amounts of torques are applied in the molar areas. a clinically effective moment is between 5 and 20 Nmm. In this study we have decided to evaluate the impact of different tube sizes and different dimensions of wires with different modulus of elasticities on the amount torsional bond strength of molar tubes. 60 human impacted molar teeth were collected. A buccal tube was bonded on the buccal surface of all the samples by using light cured adhesive resin. After that, the teeth were mounted in a hard acrylic block. According to the size of buccal tube and the rectangular wires to be tested 4 groups will be designed. Torsional force was applied by instron machine. The torque angle at 5Nmm and at 20Nmm point will be calculated: which means, how many degrees of torque is required to reach the maximum 20Nmm moment from the minimum 5Nmm.One-way ANOVA was used to compare torque angle in all of the groups. The least amount of clinically significant angle was 2.2 ᵒ in the 0.017×0.025 SS and the largest amount of it was 23.7 ᵒ in the 0.017×0.025 TMA in 0.018×0.025 slot molar tube. But, this angle was 19.9 ᵒand 13.6 ᵒ in 0.019×0.025 SS and 0.019×0.025 TMA archwire in 0.022×0.028 molar tube. The 0.017×0.025 SS archwire in 0.018×0.025 molar tube had the lowest clinically significant angle. The largest amount was seen in group 0.017×0.025 TMA in 0.018×0.025 slot molar tube. Key words: Torsional efficacy, rectangular wires, buccal tubes, torque angle.
On the prediction of single-phase forced convection heat transfer in narrow rectangular channels
International Nuclear Information System (INIS)
Ghione, Alberto; Noel, Brigitte; Vinai, Paolo; Demazière, Christophe
2014-01-01
In this paper, selected heat transfer correlations for single-phase forced convection are assessed for the case of narrow rectangular channels. The work is of interest in the thermal-hydraulic analysis of the Jules Horowitz Reactor (JHR), which is a research reactor under construction at CEA-Cadarache (France). In order to evaluate the validity of the correlations, about 300 tests from the SULTAN-JHR database were used. The SULTAN-JHR program was carried out at CEA-Grenoble and it includes different kinds of tests for two different vertical rectangular channels with height of 600 mm and gap of 1.51 and 2.16 mm. The experimental conditions range between 2 - 9 bar for the pressure; 0.5 - 18 m/s for the coolant velocity and 0.5 - 7.5 MW/m 2 for the heat flux (whose axial distribution is uniform). Forty-two thermocouples and eight pressure taps were placed at several axial locations, measuring wall temperature and pressure respectively. The analysis focused on turbulent flow with Reynolds numbers between 5.5 x 10 3 - 2.4 x 10 5 and Prandtl numbers between 1.5 - 6. It was shown that standard correlations as the Dittus-Boelter and Seider-Tate significantly under-estimate the heat transfer coefficient, especially at high Reynolds number. Other correlations specifically designed for narrow rectangular channels were also taken into account and compared. The correlation of Popov-Petukhov in the form suggested by Siman-Tov still under-estimates the heat transfer coefficient, even if slight improvements could be seen. A better agreement for the tests with gap equal to 2.16 mm could be found with the correlation of Ma and the one of Liang. However the heat transfer coefficient when the gap is equal to 1.51 mm could not be predicted accurately. Furthermore these correlations were based on data at low Reynolds numbers (up to 13000) and low heat flux, so the use of them for SULTAN-JHR may be questionable. According to the authors’ knowledge, existing models of heat transfer
Performance of an inclined solar still with rectangular grooves and ridges
International Nuclear Information System (INIS)
Anburaj, P.; Kalidasa, Murugavel K.; Samuel Hansen, R.
2013-01-01
This work investigates the experimental performance of a new type inclined solar still with rectangular grooves and ridges in absorber plate. The still was fabricated and tested for various inclination angles of 25, 30 and 35 facing south with absorber plate. Performances of the still were compared with different wick materials (Black cotton cloth, Jute cloth, and Waste cotton pieces) on the absorber plate. The effect of placing porous material (Clay pot) and energy storing material (Mild steel pieces) in the grooves were studied. The results demonstrate that 30 inclination is optimum which yielded 3.77 L/day production. Compared to different wick materials, black cotton cloth helps to achieve maximum productivity of 4.21 L/day. The addition of permeable materials and energy absorbing materials also enhances the distillate output to 4.27 L/day. (authors)
Directory of Open Access Journals (Sweden)
Fengming Wang
2012-12-01
Full Text Available The flow and heat transfer characteristics inside a rectangular channel embedded with pin fins were numerically and experimentally investigated. Several differently shaped pin fins (i.e., circular, elliptical, and drop-shaped with the same cross-sectional areas were compared in a staggered arrangement. The Reynolds number based on the obstructed section hydraulic diameter (defined as the ratio of the total wetted surface area to the open duct volume available for flow was varied from 4800 to 8200. The more streamlined drop-shaped pin fins were better at delaying or suppressing separation of the flow passing through them, which decreased the aerodynamic penalty compared to circular pin fins. The heat transfer enhancement of the drop-shaped pin fins was less than that of the circular pin fins. In terms of specific performance parameters, drop-shaped pin fins are a promising alternative configuration to circular pin fins.
Directory of Open Access Journals (Sweden)
Jablonská Jana
2016-08-01
Full Text Available Cavitation is a phenomenon with both positive and negative effects and with dynamic manifestations in hydraulic, food, chemical and other machinery. This article deals with the detection and dynamic behavior of cavitation clouds in water flows through a rectangular cross-section convergent-divergent nozzle. Cavitation was measured by methods applicable in engineering practice. Pressure, flow rate, noise, vibration, and amount of air dissolved in the liquid were measured and cavitation region was recorded with a high-speed camera. Evaluation of acquired images in connection with measured pressure pulsations and mechanical vibrations was performed with the use of the FFT method. In certain cases, dimensionless parameters were used to generalize the measurements. The results will be used to specify multiphase mathematical cavitation model parameters.
Liquid-metal flow in a rectangular duct with a non-uniform magnetic field
International Nuclear Information System (INIS)
Walker, J.S.
1986-04-01
This paper treats liquid-metal flow in rectangular ducts with thin conducting walls. A transverse magnetic field changes from a uniform strength upstream to a weaker uniform strength downstream. The Hartmann number and the interaction parameter are assumed to be large, while the magnetic Reynolds number is assumed to be small. If the magnetic field changes gradually over a long duct length, the velocity and pressure are nearly uniform in each cross section and the flow differs slightly from locally fully developed flow. If the magnetic field changes more abruptly over a shorter duct length, the velocity and pressure are much larger near the walls parallel to the magnetic field than in the central part of duct. Solutions for the pressure drops due to the magnetic field change are presented
Flame Quenching Dynamics of High Velocity Flames in Rectangular Cross-section Channels
Mahuthannan, Ariff Magdoom; Lacoste, Deanna; Damazo, Jason; Kwon, Eddie; Roberts, William L.
2017-01-01
Understanding flame quenching for different conditions is necessary to develop safety devices like flame arrestors. In practical applications, the speed of a deflagration in the lab-fixed reference frame will be a strong function of the geometry through which the deflagration propagates. This study reports on the effect of the flame speed, at the entrance of a quenching section, on the quenching distance. A 2D rectangular channel joining two main spherical vessels is considered for studying this effect. Two different velocity regimes are investigated and referred to as configurations A, and B. For configuration A, the velocity of the flame is 20 m/s, while it is about 100 m/s for configuration B. Methane-air stoichiometric mixtures at 1 bar and 298 K are used. Simultaneous dynamic pressure measurements along with schlieren imaging are used to analyze the quenching of the flame. Risk assessment of re-ignition is also reported and analyzed.
An approach to global equalisation in a rectangular room at low frequencies
DEFF Research Database (Denmark)
Orozco, Arturo
1999-01-01
The motivation of this study is the fact that sound reproduced in a room undergoes a spectral colouration, which is undesirable. This effect is particularly severe at low frequencies in small enclosures.A theoretical study based on computer simulations is presented. The listening area is a contin......The motivation of this study is the fact that sound reproduced in a room undergoes a spectral colouration, which is undesirable. This effect is particularly severe at low frequencies in small enclosures.A theoretical study based on computer simulations is presented. The listening area...... is a continuous region in a rectangular room that occupies almost the entire room. A travelling wave is generated by feeding a number of loudspeakes with the signal to be reproduced passed through digital filters. The problem of designing these filters is investigated both in the frequency domain and in the time...
Energy Technology Data Exchange (ETDEWEB)
Kim, Dong Eok; Myung, Byung-Soo [Kyungpook Nat’l Univ., Daegu (Korea, Republic of); Park, Su Cheong; Yu, Dong In [POSTECH, Pohang (Korea, Republic of); Kim, Moo Hwan [Korea Institute of Nuclear Safety (KINS), Daejeon (Korea, Republic of); Ahn, Ho Seon [Incheon Nat’l Univ., Incheon (Korea, Republic of)
2016-06-15
Based on a surface design with rectangular cavities and channels, we investigated the effects of gravity and capillary pressure on pool-boiling Critical Heat Flux (CHF). The microcavity structures could prevent liquid flow by the capillary pressure effect. In addition, the microchannel structures contributed to induce one-dimensional liquid flow on the boiling surface. The relationship between the CHF and capillary flow was clearly established. The driving potentials for the liquid supply into a boiling surface can be generated by the gravitational head and capillary pressure. Through an analysis of pool boiling and visualization data, we reveal that the liquid supplement to maintain the nucleate boiling condition on a boiling surface is closely related to the gravitational pressure head and capillary pressure effect.
International Nuclear Information System (INIS)
Mitsuoka, Shigenori; Tamura, Akira
2011-01-01
Assuming that an electron confined by double δ-function barriers lies in a quasi-stationary state, we derived eigenstates and eigenenergies of the electron. Such an electron has a complex eigenenergy, and the imaginary part naturally leads to the lifetime of the electron associated with tunneling through barriers. We applied this point of view to the electron confined in a rectangular quantum corral (QC) on a noble metal surface, and obtained scanning tunneling microscopic images and a scanning tunneling spectrum consistent with experimental ones. We investigated the electron states confined in coupled QCs and obtained the coupled states constructed with bonding and anti-bonding states. Using those energy levels and wavefunctions we specified scanning tunneling microscope (STM) images and scanning tunneling spectra (STS) for the doubly and triply coupled QCs. In addition we pointed out the feature of resonant electron states associated with the same QCs at both ends of the triply coupled QCs.
Progress in electrical and mechanical properties of rectangular MgB2 wires
International Nuclear Information System (INIS)
Kovac, P; Melisek, T; Kopera, L; Husek, I; Polak, M; Kulich, M
2009-01-01
Critical current densities and mechanical resistance of MgB 2 wires made by the rectangular wire-in-tube technique (RWIT) have been studied. Wires prepared from different precursor powders and variable sheath materials are compared. The best electrical performance (10 4 A cm -2 at 11.3 T) was measured for the wire with mechanically alloyed powder doped by SiC. While the critical current densities, J c , at 4.2 K are considerably influenced by the powder used, the differences at 20 K are much smaller. Flattened wires show different levels of critical current anisotropy influenced by the precursor powder used. Stress-strain characteristics and critical current degradation are strongly affected by the applied metallic materials and also by the filament's strength. The highest irreversible strain ε irr = 0.55% was measured for Ti/Cu/Monel sheathed wire with filaments from mechanically alloyed powder.
Topology optimization for elastic base under rectangular plate subjected to moving load
Directory of Open Access Journals (Sweden)
Jilavyan Samvel H.
2015-09-01
Full Text Available Distribution optimization of elastic material under elastic isotropic rectangular thin plate subjected to concentrated moving load is investigated in the present paper. The aim of optimization is to damp its vibrations in finite (fixed time. Accepting Kirchhoff hypothesis with respect to the plate and Winkler hypothesis with respect to the base, the mathematical model of the problem is constructed as two-dimensional bilinear equation, i.e. linear in state and control function. The maximal quantity of the base material is taken as optimality criterion to be minimized. The Fourier distributional transform and the Bubnov-Galerkin procedures are used to reduce the problem to integral equality type constraints. The explicit solution in terms of two- dimensional Heaviside‘s function is obtained, describing piecewise-continuous distribution of the material. The determination of the switching points is reduced to a problem of nonlinear programming. Data from numerical analysis are presented.
Directory of Open Access Journals (Sweden)
Huimin Liu
2017-01-01
Full Text Available This paper presents the first known vibration characteristic of rectangular thick plates on Pasternak foundation with arbitrary boundary conditions on the basis of the three-dimensional elasticity theory. The arbitrary boundary conditions are obtained by laying out three types of linear springs on all edges. The modified Fourier series are chosen as the basis functions of the admissible function of the thick plates to eliminate all the relevant discontinuities of the displacements and their derivatives at the edges. The exact solution is obtained based on the Rayleigh–Ritz procedure by the energy functions of the thick plate. The excellent accuracy and reliability of current solutions are demonstrated by numerical examples and comparisons with the results available in the literature. In addition, the influence of the foundation coefficients as well as the boundary restraint parameters is also analyzed, which can serve as the benchmark data for the future research technique.
Three-dimensional numerical simulations of turbulent cavitating flow in a rectangular channel
Iben, Uwe; Makhnov, Andrei; Schmidt, Alexander
2018-05-01
Cavitation is a phenomenon of formation of bubbles (cavities) in liquid as a result of pressure drop. Cavitation plays an important role in a wide range of applications. For example, cavitation is one of the key problems of design and manufacturing of pumps, hydraulic turbines, ship's propellers, etc. Special attention is paid to cavitation erosion and to performance degradation of hydraulic devices (noise, fluctuations of the mass flow rate, etc.) caused by the formation of a two-phase system with an increased compressibility. Therefore, development of a model to predict cavitation inception and collapse of cavities in high-speed turbulent flows is an important fundamental and applied task. To test the algorithm three-dimensional simulations of turbulent flow of a cavitating liquid in a rectangular channel have been conducted. The obtained results demonstrate the efficiency and robustness of the formulated model and the algorithm.
Hochman, J. M.; Gilgenbach, R. M.; Jaynes, R. L.; Rintamaki, J. I.; Luginsland, J. W.; Lau, Y. Y.; Spencer, T. A.
1996-11-01
Experiments utilize large and small orbit e-beam gyrotron devices in a rectangular-cross-section (RCS) gyrotron. This device is being explored to examine polarization control. Other research issues include pulse shortening, and mode competition. MELBA generates electron beams with parameters of: -800kV, 1-10kA diode current, and 0.5-1.0 μ sec pulselengths. The small orbit gyrotron device is converted to a large orbit experiment by running MELBA's annular electron beam through a magnetic cusp. Initial experiments showed an increase in beam alpha (V_perp/V_par) of a factor of ~ 4 between small and large orbit devices. Experimental results from the RCS gyrotron will be compared for large-orbit and small-orbit electron beams. Beam transport data and frequency measurements will be presented. Computer modeling utilizing the MAGIC and E-gun codes will be shown.
Experimental investigation of onset of nucleate boiling in this rectangular channels
International Nuclear Information System (INIS)
Belhadj, M.; Christensen, R.N.; Aldemir, T.
1988-01-01
The 10 kW, HEU fueled Ohio State University Research Reactor (OSURR) will be upgraded to operate with plate type LEU U 3 Si 2 , fuel elements in the power range 250-500 kW. The core will be cooled by natural convection and an onset of nucleate boiling (ONB) margin of 1.2 will be maintained in the hot channel under steady-state operation. The validity of the correlations used for predicting ONB in plate type research reactors is not known for low heat flux-low velocity flows. An experiment has been set up at The Ohio State University to investigate ONB for laminar flow in this rectangular channels. The results show that: The Bergles-Rohsenow correlation and the correlation proposed by Ricque and Siboul predict higher and lower ONB fluxes than actual, respectively. The ONB heat flux is flow velocity dependent
Active control of radiated sound power from a baffled, rectangular panel
DEFF Research Database (Denmark)
Mørkholt, Jakob
1996-01-01
with an array of eleven microphones in front of the panel, is very close to minimising the actual radiated sound power. Practical experiments where such an array estimate has been minimised using the filtered X LMS algorithm have shown that substantial reductions of radiated sound power can be obtained over......Active control of radiated sound power from a rectangular baffled panel by minimisation of an accurate power estimate, using piezoceramic actuators, has been investigated. Computer simulations have shown that minimising a power estimate obtained by discretised integration of the far field intensity...... a broad frequency range using few piezoceramic actuators, provided that an accurate estimate of the sound power is available for minimisation....
International Nuclear Information System (INIS)
Hua, T.Q.; Walker, J.S.; Picologlou, B.F.; Reed, C.B.
1988-07-01
Magnetohydrodynamic flows of liquid metals in rectangular ducts with thin conducting walls in the presence of strong nonuniform transverse magnetic fields are examined. The interaction parameter and Hartmann number are assumed to be large, whereas the magnetic Reynolds number is assumed to be small. Under these assumptions, viscous and inertial effects are confined in very thin boundary layers adjacent to the walls. A significant fraction of the fluid flow is concentrated in the boundary layers adjacent to the side walls which are parallel to the magnetic field. This paper describes the analysis and numerical methods for obtaining 3-D solutions for flow parameters outside these layers, without solving explicitly for the layers themselves. Numerical solutions are presented for cases which are relevant to the flows of liquid metals in fusion reactor blankets. Experimental results obtained from the ALEX experiments at Argonne National Laboratory are used to validate the numerical code. In general, the agreement is excellent. 5 refs., 14 figs
International Nuclear Information System (INIS)
Yan Changqi; Jin Guangyuan; Sun Licheng; Wang Yang
2015-01-01
Characteristics of local parameters of bubbly flow were investigated in rectangular channel (40 mm × 3 mm) under inclined and rolling conditions. Under vertical condition, the distribution type 'wall peak' and 'core peak' are observed, and 'core peak' exists when the liquid superficial velocity is low and the gas superficial velocity is high. Under inclined condition, the peaks of two distribution types get strengthened at the top of the channel, and weakened at the bottom. Under rolling condition, the peaks of two distribution types get strengthened compared with the same angle under inclined condition when the angle is getting larger. The influence from rolling motion gets stronger on the peak of two distribution types when the rolling movement is more violent. (authors)
Viswanathan, A. V.; Tamekuni, M.; Baker, L. L.
1974-01-01
A method is presented to predict theoretical buckling loads of long, rectangular flat and curved laminated plates with arbitrary orientation of orthotropic axes each lamina. The plate is subjected to combined inplane normal and shear loads. Arbitrary boundary conditions may be stipulated along the longitudinal sides of the plate. In the absence of inplane shear loads and extensional-shear coupling, the analysis is also applicable to finite length plates. Numerical results are presented for curved laminated composite plates with boundary conditions and subjected to various loadings. These results indicate some of the complexities involved in the numerical solution of the analysis for general laminates. The results also show that the reduced bending stiffness approximation when applied to buckling problems could lead to considerable error in some cases and therefore must be used with caution.
Directory of Open Access Journals (Sweden)
Alireza Shooshtari
Full Text Available Abstract Free vibration of a magnetoelectroelastic rectangular plate is investigated based on the Reddy's third-order shear deformation theory. The plate rests on an elastic foundation and it is considered to have different boundary conditions. Gauss's laws for electrostatics and magnetostatics are used to model the electric and magnetic behavior. The partial differential equations of motion are reduced to a single partial differential equation and then by using the Galerkin method, the ordinary differential equation of motion as well as an analytical relation for the natural frequency of the plate is obtained. Some numerical examples are presented to validate the proposed model and to investigate the effects of several parameters on the vibration frequency of the considered smart plate.
International Nuclear Information System (INIS)
Xu Jianjun; Chen Bingde; Wang Xiaojun
2011-01-01
The characteristic of the coalesced sliding bubble was visually observed by wide side and narrow side of the narrow rectangular channel using high speed digital camera. The results show that the coalesced time among the sliding bubbles is quick, and the new formation of coalesced bubble is not lift-off, and it continues to slide along the heated surface in low heat flux for the isolated bubble region. The influence region is about 2 times projected area of the sliding bubble when the sliding bubbles begin to interact. The sliding bubble velocities increase duo to the interaction among the bubbles, which contributes to enhance heat transfer of this region. Finally, the effect of coalesced interaction of growing bubble in the nucleation sites on bubble lift-off was discussed and analysed. (authors)
Computationally Efficient 2D DOA Estimation with Uniform Rectangular Array in Low-Grazing Angle
Directory of Open Access Journals (Sweden)
Junpeng Shi
2017-02-01
Full Text Available In this paper, we propose a computationally efficient spatial differencing matrix set (SDMS method for two-dimensional direction of arrival (2D DOA estimation with uniform rectangular arrays (URAs in a low-grazing angle (LGA condition. By rearranging the auto-correlation and cross-correlation matrices in turn among different subarrays, the SDMS method can estimate the two parameters independently with one-dimensional (1D subspace-based estimation techniques, where we only perform difference for auto-correlation matrices and the cross-correlation matrices are kept completely. Then, the pair-matching of two parameters is achieved by extracting the diagonal elements of URA. Thus, the proposed method can decrease the computational complexity, suppress the effect of additive noise and also have little information loss. Simulation results show that, in LGA, compared to other methods, the proposed methods can achieve performance improvement in the white or colored noise conditions.
A Novel CPW BandPass Filter Integrating Periodic Rectangular Slot Cells
Directory of Open Access Journals (Sweden)
Fouad Aytouna
2015-12-01
Full Text Available In this paper, we introduce the design and the achievement of a Bandpass filter structure based on the use of rectangular slot cell. The originality of this work is to achieve a coplanar filter easy to integrate with microwave planar circuits and having a wide frequency bandwidth. The proposed bandpass filter is a low cost and compact planar filter structure. The final circuit is simulated by using two electromagnetic solvers, ADS and HFSS. The validation into simulation is based on using optimization methods integrated into the both solvers. Simulations have taken into account a high meshing density to cover the whole circuit. The fabricated bandpass filter has an area of 35X31mm2 and having a good insertion loss around -0.75dB in the bandwidth. The comparison between simulation and measurement results presents a good agreement.
Directory of Open Access Journals (Sweden)
Manuel Mendez-Astudillo
2017-04-01
Full Text Available We report on evanescently coupled rectangular microresonators with dimensions up to 20 × 10 μm2 in silicon-on-insulator in an add-drop filter configuration. The influence of the geometrical parameters of the device was experimentally characterized and a high Q value of 13,000 was demonstrated as well as the multimode optical resonance characteristics in the drop port. We also show a 95% energy transfer between ports when the device is operated in TM-polarization and determine the full symmetry of the device by using an eight-port configuration, allowing the drop waveguide to be placed on any of its sides, providing a way to filter and route optical signals. We used the FDTD method to analyze the device and e-beam lithography and dry etching techniques for fabrication.
Discharge coefficient of a rectangular sharp-edged broad-crested weir
Directory of Open Access Journals (Sweden)
Zachoval Zbyněk
2014-06-01
Full Text Available This paper is concerned with the determination of the relationship for the calculation of the discharge coefficient at free overflow over a rectangular sharp-edged broad-crested weir without lateral contraction. The determination was made on the basis of new measurement in a range of the relative thickness of the weir from 0.12 to 0.30 and newly in a large range of relative height of the weir extremely from 0.24 to 6.8 which greatly expands the application possibilities of low weirs. In addition, the effects of friction and surface tension on the value of the discharge coefficient were evaluated as well as the effect of the relative thickness of the weir. The new equation for discharge coefficient, expressed using the relative height of the weir, was subjected to verification made by an independent laboratory which confirmed its accuracy.
International Nuclear Information System (INIS)
Gera, B.; Singh, R.K.; Vaze, K.K.
2014-01-01
Premixed hydrogen/air combustion in an upright, rectangular shaped combustion chamber has been performed numerically using commercial CFD code CFD-ACE+. The combustion chamber had dimensions 1 m X 0.024 m X 1 m. Simulations were carried out for 10% (v/v) hydrogen concentration for which experimental results were available. Effect of different boundary condition and ignition position on flame propagation was studied. Time dependent flame propagation in the chamber was predicted by CFD code. The computed transient flame propagation in the chamber was in good agreement with experimental results. The present work demonstrated that the available commercial CFD codes are capable of modeling hydrogen deflagration in a realistic manner. (author)
Flame Quenching Dynamics of High Velocity Flames in Rectangular Cross-section Channels
Mahuthannan, Ariff Magdoom
2017-01-05
Understanding flame quenching for different conditions is necessary to develop safety devices like flame arrestors. In practical applications, the speed of a deflagration in the lab-fixed reference frame will be a strong function of the geometry through which the deflagration propagates. This study reports on the effect of the flame speed, at the entrance of a quenching section, on the quenching distance. A 2D rectangular channel joining two main spherical vessels is considered for studying this effect. Two different velocity regimes are investigated and referred to as configurations A, and B. For configuration A, the velocity of the flame is 20 m/s, while it is about 100 m/s for configuration B. Methane-air stoichiometric mixtures at 1 bar and 298 K are used. Simultaneous dynamic pressure measurements along with schlieren imaging are used to analyze the quenching of the flame. Risk assessment of re-ignition is also reported and analyzed.
Experimental study on transition characteristics of pulsating flow in narrow rectangular channel
International Nuclear Information System (INIS)
Zhang Chuan; Tan Sichao; Liu Yusheng; Gao Puzhen; Zhao Jianing; Zhang Hong
2013-01-01
Experimental study of flow characteristic in smooth narrow rectangular channel under harmonic pulsating flow which covers laminar to turbulent flow (Reynolds number 7504-450) was carried out. The experimental results show that the frictional factors in acceleration phase of pulsating flow are higher than that in steady state, but lower than that in deceleration phase. Womersley parameter has a significant influence on the critical Reynolds number. The critical Reynolds number decreases with the increase of Womersley parameter in acceleration phase and it is opposite in deceleration phase. An empirical correlation was developed to predict the critical Reynolds number based on the experimental data, and the correlation can fit with critical Reynolds number in steady state. (authors)
Pressure drop of magnetohydrodynamic two-phase annular flow in rectangular channel
International Nuclear Information System (INIS)
Kumamaru, Hiroshige; Fujiwara, Yoshiki; Ogita, Kenji
1999-01-01
Numerical calculations have been performed on magnetohydrodynamic (MHD) two-phase annular flow in a rectangular channel with a small aspect ratio, i.e.a small ratio of the channel side perpendicular to the applied magnetic field and the side parallel to the field. Results of the present calculation agree nearly with Inoue et al.'s experimental results in the region of large liquid Reynolds numbers and large Hartmann numbers. Calculation results also show that the pressure drop ratio, i.e. the ratio of pressure drop of two-phase flow to that of single-phase flow under the same liquid flow rate and applied magnetic field, becomes lower than ∼0.02 for conditions of a fusion reactor plant. (author)
Influence of the synchrotron radiation on particle dynamics in a rectangular undulator
International Nuclear Information System (INIS)
Chin, Yong Ho.
1989-03-01
This paper is concerned with the synchrotron radiation from an undulating electron beam in a rectangular waveguide. It is shown analytically and numerically that the radiated energy spectrum may differ significantly from the free space result when the undulator length divided by the Lorentz factor of the electron beam is larger than the transverse size of the waveguide. The undulator radiation is identified with the awake field in beam instabilities. The concepts of wake function and impedance are introduced to formulate the present problem in the same manner as the beam instability problem. It is shown that the obtained impedances satisfy the Panofsky-Wenzel theorem and other properties inevitable for wake fields. 5 refs., 2 figs
Vacuum stress tensor of a scalar field in a rectangular waveguide
International Nuclear Information System (INIS)
Rodrigues, R.B.; Svaiter, N.F.; Paola, R.D.M. de
2001-11-01
Using the heat Kernel method and the analytical continuation of the zeta function, we calculate the canonical and improved vacuum stress tensors, {T μν (vector x)} and {Θ μν (vector x)}, associated with a massless scalar field confined in the interior of an infinity long rectangular waveguide. The local depence of the renormalized energy for two special configurations when the total energy is positive and negative are presented using {T 00 (vector x)} and {Θ 00 (vector x)}. From the stress tensors we obtain the local casimir forces in all walls by introducing a particular external configuration. It is hown that this external configuration cannot give account of the edge divergences of the local forces. The local form of the forces is obtained for three special configurations. (author)
Directory of Open Access Journals (Sweden)
Yue Wang
2016-04-01
Full Text Available Transmission spectra of terahertz waves through a two-dimensional array of asymmetric rectangular apertures on super-aligned multi-walled carbon nanotube films were obtained experimentally. In this way, the anisotropic transmission phenomena of carbon nanotube films were observed. For a terahertz wave polarization parallel to the orientation of the carbon nanotubes and along the aperture short axis, sharp resonances were observed and the resonance frequencies coincided well with the surface plasmon polariton theory. In addition, the minima of the transmission spectra were in agreement with the location predicted by the theory of Wood’s anomalies. Furthermore, it was found that the resonance profiles through the carbon nanotube films could be well described by the Fano model.
Unsteady cavity flow around a rectangular cylinder; Kakuchu mawari no hiteijo cavitation nagare
Energy Technology Data Exchange (ETDEWEB)
Takahashi, T.; Kaga, T.; Ota, T. [Tohoku University, Sendai (Japan). Faculty of Engineering; Mori, T. [Hachinohe Institute of Technology, Aomori (Japan)
1995-08-25
Unsteady cavity flow around a rectangular cylinder was observed using a high-speed camera. To clarify the correlation between the cavity behavior and fluid dynamic characteristics in the transitional region and supercavitation, fluctuating forces and surface pressures on the cylinder surface were recorded simultaneously. The tested cylinder has a critical width-to-height ration 2.8, in which the shear layer separated from the leading edge intermittently reattaches near the trailing edge. Bubbly cloud originating from the separated region near the leading edge causes fluctuation of cavity termination and induces large oscillations of fluid forces and pressures. As the cavitation number decreases, the low-frequency fluctuation of the cavity developing downstream of the rear surface increases in the fluid dynamic behavior. 24 refs., 12 figs.
International Nuclear Information System (INIS)
Weissenburger, D.W.; Christensen, U.R.
1975-01-01
This report describes the derivation of three groups of equations: (1) Field components from an arbitrarily shaped filament lying in a plane. (2) Field components from an arbitrarily shaped ribbon of infinitesimal thickness with center line lying in a plane. (3) Field components from an arbitrarily shaped bar of rectangular cross section with its center line lying in a plane. In all three cases analytical expressions for the field components were found for an infinitesimal element of the cross section. These expressions are then integrated numerically along the arbitrarily shaped center line of the coil to obtain the three field components. As a check for accuracy the calculated field values of an elliptically shaped coil were compared to an existing analytic expression for a filamentary elliptical coil
Energy Technology Data Exchange (ETDEWEB)
Kurpiers, Philipp; Walter, Theodore; Magnard, Paul; Salathe, Yves; Wallraff, Andreas [ETH Zuerich, Department of Physics, Zuerich (Switzerland)
2017-12-15
Low-loss waveguides are required for quantum communication at distances beyond the chip-scale for any low-temperature solid-state implementation of quantum information processors. We measure and analyze the attenuation constant of commercially available microwave-frequency waveguides down to millikelvin temperatures and single photon levels. More specifically, we characterize the frequency-dependent loss of a range of coaxial and rectangular microwave waveguides down to 0.005 dB/m using a resonant-cavity technique. We study the loss tangent and relative permittivity of commonly used dielectric waveguide materials by measurements of the internal quality factors and their comparison with established loss models. The results of our characterization are relevant for accurately predicting the signal levels at the input of cryogenic devices, for reducing the loss in any detection chain, and for estimating the heat load induced by signal dissipation in cryogenic systems. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Bhaumik, Shankar; Guruprasad, S.; Bhandari, P. [R and DE , Dighi (India); Kumaraswamy, A. [Defence Institute of Advanced Technology, Girinagar (India)
2015-11-15
Contact based FE simulations have been carried out to estimate the contact pressure distribution at seal/rod interface at sealed oil pressures of 10, 20 and 30 MPa and constant rod velocity of 0.12 m/s. Oil film thickness at the interface was then computed analytically at various combinations of oil pressures and rod velocities. Seal contact pressure and oil film thickness data along with surface roughness, intermolecular interaction between seal/rod interfaces has been perused to estimate the friction in Nitrile-Butadiene Rubber (NBR) rectangular hydraulic rod seals using theoretical models such as Inverse hydrodynamic lubrication (IHL), Greenwood-Williamson (GW) and Wassink's models. The friction at seal/rod interface was also measured experimentally using a specially designed test rig. The comparison of theoretical and experimental data revealed that, friction computed from GW and Wassink's models had good agreement with the experimental results.
Testing of the rectangular pivot-point bellows for the PPPL tokamak fusion test reactor
International Nuclear Information System (INIS)
Haughian, J.; Lou, K.; Greer, J.; Fong, M.; Scalise, D.T.
1983-12-01
The Neutral Beam Pivot Point Bellows (PPB) is installed in the duct which connects the Neutral Beam Enclosure to the Torus. This bellows, located at the pivot point, must fit the severely limited space available at the pivot-point location. Consequently, it has to be made rectangular in cross section with a large inside area for beam access. This leads to small convolutions with high stress concentrations. The function of the bellows is to permit change in the angular positioning of the neutral beam line with respect to the Tokamak, to isolate the Neutral Beam Line from the deflection of the Torus during bake out, and to allow for all misalignments. Internally the bellows will have a vacuum along with such gases such as hydrogen or deuterium. Tests parameters are described
Gap states and edge properties of rectangular graphene quantum dot in staggered potential
Jeong, Y. H.; Eric Yang, S.-R.
2017-09-01
We investigate edge properties of a gapful rectangular graphene quantum dot in a staggered potential. In such a system gap states with discrete and closely spaced energy levels exist that are spatially located on the left or right zigzag edge. We find that, although the bulk states outside the energy gap are nearly unaffected, spin degeneracy of each gap state is lifted by the staggered potential. We have computed the occupation numbers of spin-up and -down gap states at various values of the strength of the staggered potential. The electronic and magnetic properties of the zigzag edges depend sensitively on these numbers. We discuss the possibility of applying this system as a single electron spintronic device.
Yahaya, NZ; Ramli, MR; Razak, NNANA; Abbas, Z.
2018-04-01
The Finite Element Method, FEM has been successfully used to model a simple rectangular microstrip sensor to determine the moisture content of Hevea rubber latex. The FEM simulation of sensor and samples was implemented by using COMSOL Multiphysics software. The simulation includes the calculation of magnitude and phase of reflection coefficient and was compared to analytical method. The results show a good agreement in finding the magnitude and phase of reflection coefficient when compared with analytical results. Field distributions of both the unloaded sensor as well as the sensor loaded with different percentages of moisture content were visualized using FEM in conjunction with COMSOL software. The higher the amount of moisture content in the sample the more the electric loops were observed.
Lee, Dukhyung; Kim, Dai-Sik
2016-01-01
We study light scattering off rectangular slot nano antennas on a metal film varying incident polarization and incident angle, to examine which field vector of light is more important: electric vector perpendicular to, versus magnetic vector parallel to the long axis of the rectangle. While vector Babinet’s principle would prefer magnetic field along the long axis for optimizing slot antenna function, convention and intuition most often refer to the electric field perpendicular to it. Here, we demonstrate experimentally that in accordance with vector Babinet’s principle, the incident magnetic vector parallel to the long axis is the dominant component, with the perpendicular incident electric field making a small contribution of the factor of 1/|ε|, the reciprocal of the absolute value of the dielectric constant of the metal, owing to the non-perfectness of metals at optical frequencies.
Analysis of flow distribution instability in parallel thin rectangular multi-channel system
Energy Technology Data Exchange (ETDEWEB)
Xia, G.L. [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an City 710049 (China); Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, Harbin Engineering University, Harbin City 150001 (China); Su, G.H., E-mail: ghsu@mail.xjtu.edu.cn [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an City 710049 (China); Peng, M.J. [Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, Harbin Engineering University, Harbin City 150001 (China)
2016-08-15
Highlights: • Flow distribution instability in parallel thin rectangular multi-channel system is studied using RELAP5 codes. • Flow excursion may bring parallel heating channel into the density wave oscillations region. • Flow distribution instability is more likely to happen at low power/flow ratio conditions. • The increase of channel number will not affect the flow distribution instability boundary. • Asymmetry inlet throttling and heating will make system more unstable. - Abstract: The flow distribution instability in parallel thin rectangular multi-channel system has been researched in the present study. The research model of parallel channel system is established by using RELAP5/MOD3.4 codes. The transient process of flow distribution instability is studied at imposed inlet mass flow rate and imposed pressure drop conditions. The influence of heating power, mass flow rate, system pressure and channel number on flow distribution instability are analyzed. Furthermore, the flow distribution instability of parallel two-channel system under asymmetric inlet throttling and heating power is studied. The results show that, if multi-channel system operates at the negative slope region of channel ΔP–G curve, small disturbance in pressure drop will lead to flow redistribution between parallel channels. Flow excursion may bring the operating point of heating channel into the density-wave oscillations region, this will result in out-phase or in-phase flow oscillations. Flow distribution instability is more likely to happen at low power/flow ratio conditions, the stability of parallel channel system increases with system pressure, the channel number has a little effect on system stability, but the asymmetry inlet throttling or heating power will make the system more unstable.
Directory of Open Access Journals (Sweden)
Yasuhisa Shinmoto
2017-11-01
Full Text Available The use of immiscible liquids for cooling of surfaces with high heat generation density is proposed based on the experimental verification of its superior cooling characteristics in fundamental systems of pool boiling and flow boiling in a tube. For the purpose of practical applications, however, heat transfer characteristics due to flow boiling in narrow rectangular channels with different small gap sizes need to be investigated. The immiscible liquids employed here are FC72 and water, and the gap size is varied as 2, 1, and 0.5 mm between parallel rectangular plates of 30 mm × 175 mm, where one plate is heated. To evaluate the effect of gap size, the heat transfer characteristics are compared at the same inlet velocity. The generation of large flattened bubbles in a narrow gap results in two opposite trends of the heat transfer enhancement due to thin liquid film evaporation and of the deterioration due to the extension of dry patch in the liquid film. The situation is the same as that observed for pure liquids. The latter negative effect is emphasized for extremely small gap sizes if the flow rate ratio of more-volatile liquid to the total is not reduced. The addition of small flow rate of less-volatile liquid can increase the critical heat flux (CHF of pure more-volatile liquid, while the surface temperature increases at the same time and assume the values between those for more-volatile and less-volatile liquids. By the selection of small flow rate ratio of more-volatile liquid, the surface temperature of pure less-volatile liquid can be decreased without reducing high CHF inherent in the less-volatile liquid employed. The trend of heat transfer characteristics for flow boiling of immiscible mixtures in narrow channels is more sensitive to the composition compared to the flow boiling in a round tube.
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RAJESH SAHA
2016-09-01
Full Text Available Radio Frequency Identification is an emerging research topic to identify any object automatically and it has applications in many fields like manufacture industry, business, animal tracking, vehicle tracking etc. In automatic identification system, the main role of radio frequency identification system is radiation and detection. The reader and the tag are the important components in radio frequency identification technology. In radio frequency identification system, antenna plays very significant role to transmit and receive data in both direction (i.e., from reader to tag and vice versa. An antenna with high gain, high directivity, high bandwidth and more down in negative S11 (dB value works as an effective antenna. So design and optimization of an effective antenna is very necessary for any application. In this paper, firstly itdesigned a rectangular patch antenna and simulated through High Frequency Structure Simulator. In next step, it designed a metamaterial structure having U shape Split Ring Resonator with both one and two port, on the rectangular patch antenna to improve the return loss and bandwidth of patch antenna; so that the performance of the tag can be increased for the radio frequency identification system. By simulation it has been seen that, two port antenna provides maximum return loss and bandwidth of - 41.2dB and 870MHz respectively. Finally, the output parameters such as return loss, gain, directivity that are obtained from simulation of the metamaterial Split Ring Resonator structure antenna are compared with the network output of Artificial Neural Network to find the Mean Square Error between the simulated output and Artificial Neural Network output.
Viscoelastic-gravitational deformation by a rectangular thrust fault in a layered earth
International Nuclear Information System (INIS)
Rundle, J.B.
1982-01-01
Previous papers in this series have been concerned with developing the numerical techniques required for the evaluation of vertical displacements which are the result of thrust faulting in a layered, elastic-gravitational earth model. This paper extends these methods to the calculation of fully time-dependent vertical surface deformation from a rectangular, dipping thrust fault in an elastic-gravitational layer over a viscoelastic-gravitational half space. The elastic-gravitational solutions are used together with the correspondence principle of linear viscoelasticity to give the solution in the Laplace transform domain. The technique used here to invert the displacements into the time domain is the Prony series technique, wherein the transformed solution is fit to the transformed representation of a truncated series of decaying exponentials. Purely viscoelastic results obtained are checked against results found previously using a different inverse transform method, and agreement is excellent. A series of results are obtained for a rectangular, 30 0 dipping thrust fault in an elastic-gravitational layer over viscoelastic-gravitational half space. Time-dependent displacements are calculated out to 50 half space relaxation times tau/sub a/, or 100 Maxwell times 2tau/sub m/ = tau/sub a/. Significant effects due to gravity are shown to exist in the solutions as early as several tau/sub a/. The difference between the purely viscoelastic solution and the viscoelastic-gravitational solutions grows as time progresses. Typically, the solutions with gravity reach an equilibrium value after 10--20 relaxation times, when the purely viscoelastic solutions are still changing significantly. Additionally, the length scaling which was apparent in the purely viscoelastic problem breaks down in the viscoelastic-gravitational problem
International Nuclear Information System (INIS)
Krishnani, Mayur; Basu, Dipankar N.
2017-01-01
Highlights: • Computational model developed for single-phase rectangular natural circulation loop. • Role of loop inclination to vertical on thermalhydraulic stability is explored. • Inclination has strong stabilizing effect due to lower effective gravitation force. • Increase in tilt angle reduces settling time and highest amplitude of oscillation. • An angle of 15° is suggested for the selected loop geometry. - Abstract: Controlling stability behavior of single-phase natural circulation loops, without significantly affecting its steady-state characteristics, is a topic of wide research interest. Present study explores the role of loop inclination on a particular loop geometry. Accordingly a 3D computational model of a rectangular loop is developed and transient conservation equations are solved to obtain the temporal variation in flow parameters. Starting from the quiescent state, simulations are performed for selected sets of operating conditions and also with a few selected inclination angles. System experiences instability at higher heater powers and also with higher sink temperatures. Inclination is found to have a strong stabilizing influence owing to the reduction in the effective gravitational acceleration and subsequent decline in local buoyancy effects. The settling time and highest amplitude of oscillations substantially reduces for a stable system with a small inclination. Typically-unstable systems can also suppress the oscillations, when subjected to tilting, within a reasonable period of time. It is possible to stabilize the loop within shorter time span by increasing the tilt angle, but at the expense of reduction in steady-state flow rate. Overall a tilt angle of 15° is suggested for the selected geometry. Results from the 3D model is compared with the predictions from an indigenous 1D code. While similar qualitative influence of inclination is observed, the 1D model predicts early appearance of the stability threshold and hence hints
Heat Transfer Augmentation in Gas Turbine Blade Rectangular Passages Using Circular Ribs with Fins
Directory of Open Access Journals (Sweden)
Mohammed W. Al-Jibory
2017-11-01
Full Text Available In this paper, an experimental system was designed and built to simulate conditions in the gas turbine blade cooling and run the experimental part. Boundary conditions are: inlet coolant air temperature is 300K with Reynolds numbers (Re=7901 .The surrounding constant hot air temperatures was (673 K.The numerical simulations were done by using software FLUENT version (14.5, in this part, it was presented the effect of using circular ribs having middle fin fitted in rectangular passage channel on fluid flow and heat transfer characteristics. Ribs used with pitch-rib height of 10, rectangular channel of (30x60 mm cross section, 1.5 mm duct thickness and 0.5 m long. The temperature, velocity distribution contours, cooling air temperature distribution at the duct centerline, the inner wall surface temperature of the duct, and thermal performance factor are presented in this paper. it can be seen that the duct with all ribs with middle fins was the better case which leads to increase the coolant air temperature by (10.22 % and decrease the inner wall temperature by (6.15 % . The coolant air flow velocity seems to be accelerated and decelerated through the channel in the presence of ribs, so it was shown that the thermal performance factor along the duct is larger than 1, this is due to the fact that the ribs create turbulent conditions and increasing thermal surface area, and thus increasing heat transfer coefficient than the smooth channel.
Directory of Open Access Journals (Sweden)
Mingzhong Gao
Full Text Available Rectangular caverns are increasingly used in underground engineering projects, the failure mechanism of rectangular cavern wall rock is significantly different as a result of the cross-sectional shape and variations in wall stress distributions. However, the conventional computational method always results in a long-winded computational process and multiple displacement solutions of internal rectangular wall rock. This paper uses a Laurent series complex method to obtain a mapping function expression based on complex variable function theory and conformal transformation. This method is combined with the Schwarz-Christoffel method to calculate the mapping function coefficient and to determine the rectangular cavern wall rock deformation. With regard to the inverse mapping concept, the mapping relation between the polar coordinate system within plane ς and a corresponding unique plane coordinate point inside the cavern wall rock is discussed. The disadvantage of multiple solutions when mapping from the plane to the polar coordinate system is addressed. This theoretical formula is used to calculate wall rock boundary deformation and displacement field nephograms inside the wall rock for a given cavern height and width. A comparison with ANSYS numerical software results suggests that the theoretical solution and numerical solution exhibit identical trends, thereby demonstrating the method's validity. This method greatly improves the computing accuracy and reduces the difficulty in solving for cavern boundary and internal wall rock displacements. The proposed method provides a theoretical guide for controlling cavern wall rock deformation failure.
Mansuri, Samir; Abdulkhayum, Abdul Mujeeb; Gazal, Giath; Hussain, Mohammed Abid Zahir
2013-12-01
Surgical treatment of fracture mandible using an internal fixation has changed in the last decades to achieve the required rigidity, stability and immediate restoration of function. The aim of the study was to do a Prospective study of 10 patients to determine the efficacy of rectangular grid compression miniplates in mandibular fractures. This study was carried out using 2.0 rectangular grid compression miniplates and 8 mm multidirectional screws as a rigid internal fixation in 10 patients without post operative intermaxillary fixation (IMF). Follow up was done for period of 6 months. All fractures were healed with an absolute stability in post operative period. None of the patient complained of post operative difficulty in occlusion. Within the limits of this study, it can be concluded that rectangular grid compression miniplates was rigid, reliable and thus can be recommended for the treatment of mandibular angle fractures. How to cite this article: Mansuri S, Abdulkhayum AM, Gazal G, Hussain MA. Treatment of mandibular angle fracture with a 2mm, 3 dimensional rectangular grid compression miniplates: A prospective clinical study. J Int Oral Health 2013;5(6):93-100 .
Directory of Open Access Journals (Sweden)
Webb John K
2002-10-01
Full Text Available Abstract Background Recent cadaver studies show stability against axial rotation with a cylindrical cage is marginally superior to a rectangular cage. The purpose of this biomechanical study in cadaver spine was to evaluate the stability of a new rectangular titanium cage design, which has teeth similar to the threads of cylindrical cages to engage the endplates. Methods Ten motion segments (five L2-3, five L4-5 were tested. From each cadaver spine, one motion segment was fixed with a pair of cylindrical cages (BAK, Sulzer Medica and the other with paired rectangular cages (Rotafix, Corin Spinal. Each specimen was tested in an unconstrained state, after cage introduction and after additional posterior translaminar screw fixation. The range of motion (ROM in flexion-extension, lateral bending, and rotation was tested in a materials testing machine, with +/- 5 Nm cyclical load over 10 sec per cycle; data from the third cycle was captured for analysis. Results ROM in all directions was significantly reduced (p Conclusions There was no significant difference in immediate stability in any direction between the threaded cylindrical cage and the new design of the rectangular cage with endplate teeth.
International Nuclear Information System (INIS)
Felker, B.; Calderon, M.O.; Chargin, A.K.
1983-01-01
The electron-cyclotron-resonant heating (ECRH) systems of rectangular waveguides on Tandem Mirror Experiment-Upgrade (TMX-U) operated with a overall efficiency of 50%, each system using a 28-GHz, 200-kW pulsed gyrotron. We designed and built four circular-waveguide systems with greater efficiency and greater power-handling capabilities to replace the rectangular waveguides. Two of these circular systems, at the 5-kG second-harmonic heating locations, have a total transmission efficiency of >90%. The two systems at the 10-kG fundamental heating locations have a total transmission efficiency of 80%. The difference in efficiency is due to the additional components required to launch the microwaves in the desired orientation and polarization with respect to magnetic-field lines at the 10-kG points. These systems handle the total power available from each gyrotron but do not have the arcing limitation problem of the rectangular waveguide. Each system requires several complex components. The overall physical layout and the design considerations for the rectangular and circular waveguide components are described here
Energy Technology Data Exchange (ETDEWEB)
Felker, B.; Calderon, M.O.; Chargin, A.K.; Coffield, F.E.; Lang, D.D.; Rubert, R.R.; Pedrotti, L.R.; Stallard, B.W.; Gallagher, N.C. Jr.; Sweeney, D.W.
1983-11-18
The electron-cyclotron-resonant heating (ECRH) systems of rectangular waveguides on Tandem Mirror Experiment-Upgrade (TMX-U) operated with a overall efficiency of 50%, each system using a 28-GHz, 200-kW pulsed gyrotron. We designed and built four circular-waveguide systems with greater efficiency and greater power-handling capabilities to replace the rectangular waveguides. Two of these circular systems, at the 5-kG second-harmonic heating locations, have a total transmission efficiency of >90%. The two systems at the 10-kG fundamental heating locations have a total transmission efficiency of 80%. The difference in efficiency is due to the additional components required to launch the microwaves in the desired orientation and polarization with respect to magnetic-field lines at the 10-kG points. These systems handle the total power available from each gyrotron but do not have the arcing limitation problem of the rectangular waveguide. Each system requires several complex components. The overall physical layout and the design considerations for the rectangular and circular waveguide components are described here.
Yang, Jiashi; Liu, Jinjin; Li, Jiangyu
2007-04-01
A rectangular ceramic plate with appropriate electrical load and operating mode is analyzed for piezoelectric transformer application. An exact solution from the three-dimensional equations of linear piezoelectricity is obtained. The solution simulates the real operating situation of a transformer as a vibrating piezoelectric body connected to a circuit. Transforming ratio, input admittance, and efficiency of the transformer are obtained.
International Nuclear Information System (INIS)
Ye Min; Lu Jing; Zhang Wei; Ding Qian
2005-01-01
The present investigation deals with nonlinear dynamic behavior of a parametrically excited simply supported rectangular symmetric cross-ply laminated composite thin plate for the first time. The governing equation of motion for rectangular symmetric cross-ply laminated composite thin plate is derived by using von Karman equation. The geometric nonlinearity and nonlinear damping are included in the governing equations of motion. The Galerkin approach is used to obtain a two-degree-of-freedom nonlinear system under parametric excitation. The method of multiple scales is utilized to transform the second-order non-autonomous differential equations to the first-order averaged equations. Using numerical method, the averaged equations are analyzed to obtain the steady state bifurcation responses. The analysis of stability for steady state bifurcation responses in laminated composite thin plate is also given. Under certain conditions laminated composite thin plate may have two or multiple steady state bifurcation solutions. Jumping phenomenon occurs in the steady state bifurcation solutions. The chaotic motions of rectangular symmetric cross-ply laminated composite thin plate are also found by using numerical simulation. The results obtained here demonstrate that the periodic, quasi-periodic and chaotic motions coexist for a parametrically excited fore-edge simply supported rectangular symmetric cross-ply laminated composite thin plate under certain conditions
Jiang, Caigui; Tang, Chengcheng; Vaxman, Amir; Wonka, Peter; Pottmann, Helmut
2015-01-01
We study the design and optimization of polyhedral patterns, which are patterns of planar polygonal faces on freeform surfaces. Working with polyhedral patterns is desirable in architectural geometry and industrial design. However, the classical
Radiation pattern synthesis of planar antennas using the iterative sampling method
Stutzman, W. L.; Coffey, E. L.
1975-01-01
A synthesis method is presented for determining an excitation of an arbitrary (but fixed) planar source configuration. The desired radiation pattern is specified over all or part of the visible region. It may have multiple and/or shaped main beams with low sidelobes. The iterative sampling method is used to find an excitation of the source which yields a radiation pattern that approximates the desired pattern to within a specified tolerance. In this paper the method is used to calculate excitations for line sources, linear arrays (equally and unequally spaced), rectangular apertures, rectangular arrays (arbitrary spacing grid), and circular apertures. Examples using these sources to form patterns with shaped main beams, multiple main beams, shaped sidelobe levels, and combinations thereof are given.