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Sample records for fresnel regime studied

  1. Babinet's principle in the Fresnel regime studied using ultrasound

    Science.gov (United States)

    Hitachi, Akira; Takata, Momo

    2010-07-01

    The diffraction of ultrasound by a circular disk and an aperture of the same size has been investigated as a demonstration of Babinet's principle in the Fresnel regime. The amplitude and the phase of the diffracted ultrasonic waves are measured and a graphical treatment of the results is performed by drawing vectors in the complex plane. The results verify Babinet's principle. It is also found that the incident wave is π /2 behind the phase of the wave passing through on the central axis of a circular aperture. Because both waves travel the same path and the same distance, they should be in phase. This paradox has previously been regarded as a defect of Fresnel's theory.

  2. Numerical Study of Concentration Characteristics of Linear Fresnel Reflector System

    International Nuclear Information System (INIS)

    Lee, Hyun Jin; Kim, Jong Kyu; Lee, Sang Nam

    2015-01-01

    In this study, we numerically investigated the concentration characteristics of a linear Fresnel reflector system that can drive a solar thermal absorption refrigeration system to be installed in Saudi Arabia. Using an optical modeling program based on the Monte Carlo ray-tracing method, we simulated the concentrated solar flux, concentration efficiency, and concentrated solar energy on four representative days of the year - the vernal equinox, summer solstice, autumnal equinox, and winter solstice. Except the winter solstice, the concentrations were approximately steady from 9 AM to 15 PM, and the concentration efficiencies exceed 70%. Moreover, the maximum solar flux around the solar receiver center changes only within the range of 13.0 - 14.6 kW/m 2 . When we investigated the effects of the receiver installation height, reflector width, and reflector gap, the optimal receiver installation height was found to be 5 m. A smaller reflector width had a greater concentration efficiency. However, the design of the reflector width should be based on the capacity of the refrigeration system because it dominantly affects the concentrated solar energy. The present study was an essential prerequisite for thermal analyses of the solar receiver. Thus, an optical-thermal integration study in the future will assist with the performance prediction and design of the entire system

  3. Numerical Study of Concentration Characteristics of Linear Fresnel Reflector System

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Jin [Kookmin Univ., Seoul (Korea, Republic of); Kim, Jong Kyu; Lee, Sang Nam [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2015-12-15

    In this study, we numerically investigated the concentration characteristics of a linear Fresnel reflector system that can drive a solar thermal absorption refrigeration system to be installed in Saudi Arabia. Using an optical modeling program based on the Monte Carlo ray-tracing method, we simulated the concentrated solar flux, concentration efficiency, and concentrated solar energy on four representative days of the year - the vernal equinox, summer solstice, autumnal equinox, and winter solstice. Except the winter solstice, the concentrations were approximately steady from 9 AM to 15 PM, and the concentration efficiencies exceed 70%. Moreover, the maximum solar flux around the solar receiver center changes only within the range of 13.0 - 14.6 kW/m{sup 2}. When we investigated the effects of the receiver installation height, reflector width, and reflector gap, the optimal receiver installation height was found to be 5 m. A smaller reflector width had a greater concentration efficiency. However, the design of the reflector width should be based on the capacity of the refrigeration system because it dominantly affects the concentrated solar energy. The present study was an essential prerequisite for thermal analyses of the solar receiver. Thus, an optical-thermal integration study in the future will assist with the performance prediction and design of the entire system.

  4. A space Fresnel imager concept assessment study led by CNES for astrophysical applications

    Science.gov (United States)

    Hinglais, Emmanuel

    2011-06-01

    In 2009, the Centre National d'Etudes Spatiales (CNES) carried out an assessment study on a "Fresnel telescope" concept based on a two-spacecraftformation flying configuration. This concept uses a binary Fresnel zone plate, and the principle of diffraction focusing, which allows high resolution optical imaging for astrophysics. In addition to CNES, the Laboratoire d'Astrophysique de Toulouse Tarbes (LATT) was deeply involved at two levels: through Research & Technology (R&T) studies to simulate and validate on a test bench the Fresnel concept performance, and through active participation in the CNES team for the optical aspects and to define the astrophysical fields of Fresnel-based space missions. The study was conducted within the technical limitations that resulted from a compromise between the R&T state of the art and the potential scientific domains of interest. The main technical limitations are linked to the size of the primary Fresnel array and to its usable spectral bandwidth. In this framework, the study covers ambitious architectures, correlating the technology readiness of the main critical components with the time-scale and programmatic horizons. The possible scientific topics arise from this range of missions. In this paper, I present a mission launched by a Soyuz, dedicated to astrophysics in the Ultra Violet (UV) band: 120 to 300 nm using a 4-m Fresnel array. It could be competitive in the next fifteen years, whereas a 10-m aperture mission in different bands; UV, visible or Infra Red (IR) (up to 6 μm) could be achievable in the future. Larger missions, using a primary array larger than 20 m, request technologies not yet available but that will probably be based on new inflatable structures with membranes, as already tested in the USA for other ends.

  5. Experimental study of refrigeration performance based on linear Fresnel solar thermal photovoltaic system

    Science.gov (United States)

    Song, Jinghui; Yuan, Hui; Xia, Yunfeng; Kan, Weimin; Deng, Xiaowen; Liu, Shi; Liang, Wanlong; Deng, Jianhua

    2018-03-01

    This paper introduces the working principle and system constitution of the linear Fresnel solar lithium bromide absorption refrigeration cycle, and elaborates several typical structures of absorption refrigeration cycle, including single-effect, two-stage cycle and double-effect lithium bromide absorption refrigeration cycle A 1.n effect absorption chiller system based on the best parameters was introduced and applied to a linear Fresnel solar absorption chiller system. Through the field refrigerator performance test, the results show: Based on this heat cycle design and processing 1.n lithium bromide absorption refrigeration power up to 35.2KW, It can meet the theoretical expectations and has good flexibility and reliability, provides guidance for the use of solar thermal energy.

  6. The fresnel interferometric imager

    Science.gov (United States)

    Koechlin, Laurent; Serre, Denis; Deba, Paul; Pelló, Roser; Peillon, Christelle; Duchon, Paul; Gomez de Castro, Ana Ines; Karovska, Margarita; Désert, Jean-Michel; Ehrenreich, David; Hebrard, Guillaume; Lecavelier Des Etangs, Alain; Ferlet, Roger; Sing, David; Vidal-Madjar, Alfred

    2009-03-01

    The Fresnel Interferometric Imager has been proposed to the European Space Agency (ESA) Cosmic Vision plan as a class L mission. This mission addresses several themes of the CV Plan: Exoplanet study, Matter in extreme conditions, and The Universe taking shape. This paper is an abridged version of the original ESA proposal. We have removed most of the technical and financial issues, to concentrate on the instrumental design and astrophysical missions. The instrument proposed is an ultra-lightweight telescope, featuring a novel optical concept based on diffraction focussing. It yields high dynamic range images, while releasing constraints on positioning and manufacturing of the main optical elements. This concept should open the way to very large apertures in space. In this two spacecraft formation-flying instrument, one spacecraft holds the focussing element: the Fresnel interferometric array; the other spacecraft holds the field optics, focal instrumentation, and detectors. The Fresnel array proposed here is a 3.6 ×3.6 m square opaque foil punched with 105 to 106 void “subapertures”. Focusing is achieved with no other optical element: the shape and positioning of the subapertures (holes in the foil) is responsible for beam combining by diffraction, and 5% to 10% of the total incident light ends up into a sharp focus. The consequence of this high number of subapertures is high dynamic range images. In addition, as it uses only a combination of vacuum and opaque material, this focussing method is potentially efficient over a very broad wavelength domain. The focal length of such diffractive focussing devices is wavelength dependent. However, this can be corrected. We have tested optically the efficiency of the chromatism correction on artificial sources (500 < λ < 750 nm): the images are diffraction limited, and the dynamic range measured on an artificial double source reaches 6.2 10 - 6. We have also validated numerical simulation algorithms for larger Fresnel

  7. Highly concentrating Fresnel lenses

    International Nuclear Information System (INIS)

    Kritchman, E.M.; Friesem, A.A.; Yekutieli, G.

    1979-01-01

    A new type of concave Fresnel lens capable of concentrating solar radiation very near the ultimate concentration limit is considered. The differential equations that describe the lens are solved to provide computed solutions which are then checked by ray tracing techniques. The performance (efficiency and concentration) of the lens is investigated and compared to that of a flat Fresnel lens, showing that the new lens is preferable for concentrating solar radiation. (author)

  8. Development of Powerhouse Using Fresnel lens

    Directory of Open Access Journals (Sweden)

    Al-Dohani Nawar Saif

    2018-01-01

    Full Text Available Solar energy is an alternative source of renewable energy. Sultanate of Oman government showed initiation on utilization of solar energy for domestic and industrial applications. Fresnel lens is one of the methods to collect maximum energy by gathering heat of the sun in the concentrated form (using solar collectors. Earlier research work discloses that Fresnel lens gave better result in terms of power output and produces lower heat loss as compared to linear –parabolic solar collectors. In this work, development of a proto Fresnel lens power house was made to generate electricity. The focused heat from Fresnel lens was used to heat the molten salt in a heat exchanger to produce the steam. The generated steam was used to rotate the steam engine coupled to a generator. In the current work, a maximum power of 30 W was produced. In addition, comparative study was carried out regarding solar salts and heat exchanger materials to understand the Fresnel powerhouse performance. Overall the present study gave valuable information regarding usage of Fresnel lens for electricity generation in Oman.

  9. Experimental and theoretical study of Bragg-Fresnel focalizing optical systems engraved on multi layers interferential mirrors adapted to X and X-UV fields

    International Nuclear Information System (INIS)

    Idir, M.

    1995-02-01

    This work concerns the study of a particular type of X-ray focusing optics known as Bragg-Fresnel lenses, formed through ion-etching of multilayered structures. Using the Super-ACO (LURE/Orsay) synchrotron storage ring, we tested several Bragg-Fresnel lenses having either linear or elliptical geometries (producing a line or a point focus, respectively). Diffraction profiles were first obtained for the linear lenses ion-etched on W/Si multilayers of nano-metric period. The experimental results were compared with our theoretical predictions. We next proposed and tested a solution to the problem superposing the different diffraction orders in the focal plane, that of fabricating Bragg-Fresnel lenses with an off-axis configuration, first for the linear and then the elliptical geometry. An experimental application, for an off-axis elliptical lens produced a focused X-ray spot of 5 x 10 microns 2 for the Super-ACO synchrotron source. The same lens also produced a 1/3-size X-ray image of a grid-like object at 1750 eV using the first and third diffraction orders. (author)

  10. Study on high concentration solar concentrator using a Fresnel lens with a secondary concentrator; Fresnel lens to niji shukokei wo mochiita solar chemistry yo kobairitsu shukokei ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, T; Suzuki, A; Fujibayashi, K [Tokyo University of Agriculture and Technology, Tokyo (Japan)

    1997-11-25

    A high concentration light collection system for solar chemistry was devised by using an inexpensive Fresnel lens in a primary concentration system and a conical type concentrator in a secondary concentration system. A Fresnel lens alone would not achieve sufficiently high light collecting magnification to attain high temperatures because of restrictions in the opening angle as seen from a focus. Therefore, a secondary concentration system was installed on a focus for an attempt of stopping. Reflection plane of a three-dimensional compound parabolic concentrator (CPC) is a rotary parabolic plane, whose process is expensive because of its surface processing accuracy. Therefore, a conical type concentrator was employed as a secondary concentration system. This system may not be capable of achieving as high concentration as in the CPC, but its shape is simple and it is inexpensive. In its optimization, a complete black body surface placed in vacuum atmosphere was hypothesized as a light concentrating part for the secondary concentration system to calculate heat collecting efficiencies at respective temperature settings. Using simultaneously the secondary concentration system, rather than collecting heat by using a Fresnel lens alone, has attained as high value as from 5.99% (500 degC) to 43.47% (1400 degC). Economical high-temperature heat collection of solar chemistry level may be possible by using a Fresnel lens and a conical secondary concentration system. 1 ref., 7 figs., 2 tabs.

  11. Experimental and theoretical study of Bragg-Fresnel focalizing optical systems engraved on multi layers interferential mirrors adapted to X and X-UV fields; Etude experimentale et theorique d`optiques focalisantes de type Bragg-Fresnel gravees sur des miroirs interferentiels multicouches adaptes aux domaines X et X-UV

    Energy Technology Data Exchange (ETDEWEB)

    Idir, M.

    1995-02-01

    This work concerns the study of a particular type of X-ray focusing optics known as Bragg-Fresnel lenses, formed through ion-etching of multilayered structures. Using the Super-ACO (LURE/Orsay) synchrotron storage ring, we tested several Bragg-Fresnel lenses having either linear or elliptical geometries (producing a line or a point focus, respectively). Diffraction profiles were first obtained for the linear lenses ion-etched on W/Si multilayers of nano-metric period. The experimental results were compared with our theoretical predictions. We next proposed and tested a solution to the problem superposing the different diffraction orders in the focal plane, that of fabricating Bragg-Fresnel lenses with an off-axis configuration, first for the linear and then the elliptical geometry. An experimental application, for an off-axis elliptical lens produced a focused X-ray spot of 5 x 10 microns{sup 2} for the Super-ACO synchrotron source. The same lens also produced a 1/3-size X-ray image of a grid-like object at 1750 eV using the first and third diffraction orders. (author).

  12. Proliferation studies for different radiotherapy fractionation regimes

    International Nuclear Information System (INIS)

    Jones, L.

    1996-01-01

    Full text: This study was undertaken to investigate extended treatment schedules and compare the differences between schedules for highly proliferative tumours. Treatment schedules can be extended for various reasons e.g. public holidays, early side effects. For highly proliferative tumours this can dramatically reduce the effective dose delivered to the tumour. To deduce the most effective schedule fractionation regimes are compared to a common schedule so that the effects can be understood. Thus an equation to allow this to be done for the proliferative case has been derived. (i) The linear quadratic model with proliferation has been used to investigate the effect on biological effective dose (BED) when treatment schedules are extended. (ii) An equation was derived for comparison with a standard effective dose (SED) of 2Gy/fraction given daily 5 days per week, this is a common schedule in most radiotherapy centres. The SED equation derived for the proliferative case is where n 1 and n 2 are the number of fractions for the initial and equivalent schedules respectively, d 1 is the dose delivered per fraction for the initial schedules. T 1 is the time taken for the initial schedule (in days) and T p is the proliferation half life for the tumour involved. SEDs were calculated for the CHART regime of 36 fractions at 1.5 Gy in 12 days (Saunders et al. 1988, cited in Fowler J F, Brit. J. Radiol. 62: 679-694, 1989) and various other schedules. Late effects of these schedules and their standard equivalents were compared. The dose required to achieve the same BED when a treatment schedule is extended has been found to be quite large in some circumstances. For breast tumours a loss of 2Gy 10 BED to tumour occurs after ten days extension of treatment time (T p =12 days,T k =12 days). For head and neck tumours a loss of 2Gy 10 BED occurs after only three and a half days (T p =3 days). From these results it seems that an accelerated fractionation schedule would be advantageous

  13. Water-core Fresnel fiber

    NARCIS (Netherlands)

    Martelli, C.; Canning, J.; Lyytikainen, K.; Groothoff, N.

    2005-01-01

    A water core photonic crystal Fresnel fiber exploiting a hole distribution on zone plates of a cylindrical waveguide was developed and characterized. This fiber has similar guiding properties as the pristine air-hole guiding fiber although a large loss edge ~900nm is observed indicating that the

  14. Experimental and theoretical study of bragg-Fresnel optics etched on multilayer structures. Application: lenses for X-Ray imaging; Etude experimentale et theorique d`optiques de bragg-Fresnel gravees sur miroirs interferentiels multicouches. Application: lentilles pour l`imagerie X

    Energy Technology Data Exchange (ETDEWEB)

    Soullie, G.

    1996-10-01

    This work concerns the study of a new type of X-ray focusing optics known as Bragg-Fresnel lenses developed for imaging in the X and X-UV range. These optics, etched on multilayer structure, combine the focusing properties of zone plate with the Bragg reflection of multilayer used like support. Using synchrotron sources and a plasma source produced by a laser, we tested the efficiency and the spatial resolution of these lenses. With a monochromatic beam, we first obtained the image of a object by using the first order diffraction of an elliptical off-axis Bragg-Fresnel lens. By using only one part of a lens, the superposition of different diffraction orders in focal plane can be avoided, thus improving the image contrast. In order to evaluate the chromatic aberrations of these lenses, we have summed on the same image, three exposures at different energies in the band pass of the multilayer. To reduce these kind of aberrations, we used a system composed of two off-axis lenses. To simplify the alignment, we tested an elliptical off-axis lens associated with a lamellar grating. Thus we are able to validate the theoretical approximation of an off-axis Bragg-Fresnel lens to a variable spaced grating. Finally, to show the perturbation brought by the zeroth order, we successively imaged a laser plasma source with a centred and an off-axis elliptical lenses. As with the synchrotron source, a set of images of a test object enabled us to improve the spatial resolution. (author).

  15. Experimental study of steam condensation regime map for simplified spargers

    International Nuclear Information System (INIS)

    Kim, Y. S.; Yoon, Y. J.; Song, C. H.; Park, C. K.; Kang, H. S.; Jun, H. K.

    2003-01-01

    An experimental study was conducted to produce a condensation regime map for single-hole and 4-hole steam spargers using GIRLS facility. The regime map for a single-hole sparger was derived using parameters such as the frequency and magnitude of the dynamic pressure. For 4-hole sparager, the regime map was derived using the trends of sound and dynamic pressure. Using the single-hole and 4-hole data, a steam jet condensation regime map was suggested with respect to pool temperature and steam mass flux

  16. An amplitude and phase hybrid modulation Fresnel diffractive optical element

    Science.gov (United States)

    Li, Fei; Cheng, Jiangao; Wang, Mengyu; Jin, Xueying; Wang, Keyi

    2018-04-01

    An Amplitude and Phase Hybrid Modulation Fresnel Diffractive Optical Element (APHMFDOE) is proposed here. We have studied the theory of APHMFDOE and simulated the focusing properties of it along the optical axis, which show that the focus can be blazed to other positions with changing the quadratic phase factor. Moreover, we design a Composite Fresnel Diffraction Optical Element (CFDOE) based on the characteristics of APHMFDOE. It greatly increases the outermost zone width without changing the F-number, which brings a lot of benefits to the design and processing of diffraction device. More importantly, the diffraction efficiency of the CFDOE is almost unchanged compared with AFZP at the same focus.

  17. Evolutionary algorithm for optimization of nonimaging Fresnel lens geometry.

    Science.gov (United States)

    Yamada, N; Nishikawa, T

    2010-06-21

    In this study, an evolutionary algorithm (EA), which consists of genetic and immune algorithms, is introduced to design the optical geometry of a nonimaging Fresnel lens; this lens generates the uniform flux concentration required for a photovoltaic cell. Herein, a design procedure that incorporates a ray-tracing technique in the EA is described, and the validity of the design is demonstrated. The results show that the EA automatically generated a unique geometry of the Fresnel lens; the use of this geometry resulted in better uniform flux concentration with high optical efficiency.

  18. Optimization of insulation of a linear Fresnel collector

    Science.gov (United States)

    Ardekani, Mohammad Moghimi; Craig, Ken J.; Meyer, Josua P.

    2017-06-01

    This study presents a simulation based optimization study of insulation around the cavity receiver of a Linear Fresnel Collector. This optimization study focuses on minimizing heat losses from a cavity receiver (maximizing plant thermal efficiency), while minimizing insulation cross-sectional area (minimizing material cost and cavity dead load), which leads to a cheaper and thermally more efficient LFC cavity receiver.

  19. Color corrected Fresnel lens for solar concentration

    International Nuclear Information System (INIS)

    Kritchman, E.M.

    1979-01-01

    A new linear convex Fresnel lens with its groove side down is described. The design philosophy is similar to the highly concentrating two focal Fresnel lens but including a correction for chromatic aberration. A solar concentration ratio as high as 80 is achieved. For wide acceptance angles the concentration nears the theoretical maximum. (author)

  20. Stretchable Binary Fresnel Lens for Focus Tuning

    NARCIS (Netherlands)

    Li, X.; Wei, L.; Poelma, R.H.; Vollebregt, S.; Wei, J.; Urbach, Paul; Sarro, P.M.; Zhang, G.Q.

    2016-01-01

    This paper presents a tuneable binary amplitude Fresnel lens produced by wafer-level microfabrication. The Fresnel lens is fabricated by encapsulating lithographically defined vertically aligned carbon nanotube (CNT) bundles inside a polydimethyl-siloxane (PDMS) layer. The composite lens material

  1. An analysis of beamed wireless power transfer in the Fresnel zone using a dynamic, metasurface aperture

    Science.gov (United States)

    Smith, David R.; Gowda, Vinay R.; Yurduseven, Okan; Larouche, Stéphane; Lipworth, Guy; Urzhumov, Yaroslav; Reynolds, Matthew S.

    2017-01-01

    Wireless power transfer (WPT) has been an active topic of research, with a number of WPT schemes implemented in the near-field (coupling) and far-field (radiation) regimes. Here, we consider a beamed WPT scheme based on a dynamically reconfigurable source aperture transferring power to receiving devices within the Fresnel region. In this context, the dynamic aperture resembles a reconfigurable lens capable of focusing power to a well-defined spot, whose dimension can be related to a point spread function. The necessary amplitude and phase distribution of the field imposed over the aperture can be determined in a holographic sense, by interfering a hypothetical point source located at the receiver location with a plane wave at the aperture location. While conventional technologies, such as phased arrays, can achieve the required control over phase and amplitude, they typically do so at a high cost; alternatively, metasurface apertures can achieve dynamic focusing with potentially lower cost. We present an initial tradeoff analysis of the Fresnel region WPT concept assuming a metasurface aperture, relating the key parameters such as spot size, aperture size, wavelength, and focal distance, as well as reviewing system considerations such as the availability of sources and power transfer efficiency. We find that approximate design formulas derived from the Gaussian optics approximation provide useful estimates of system performance, including transfer efficiency and coverage volume. The accuracy of these formulas is confirmed through numerical studies.

  2. Automated Fresnel lens tester system

    Energy Technology Data Exchange (ETDEWEB)

    Phipps, G.S.

    1981-07-01

    An automated data collection system controlled by a desktop computer has been developed for testing Fresnel concentrators (lenses) intended for solar energy applications. The system maps the two-dimensional irradiance pattern (image) formed in a plane parallel to the lens, whereas the lens and detector assembly track the sun. A point detector silicon diode (0.5-mm-dia active area) measures the irradiance at each point of an operator-defined rectilinear grid of data positions. Comparison with a second detector measuring solar insolation levels results in solar concentration ratios over the image plane. Summation of image plane energies allows calculation of lens efficiencies for various solar cell sizes. Various graphical plots of concentration ratio data help to visualize energy distribution patterns.

  3. Fresnel diffraction at an opaque strip expressed by means of asymptotic representations of Fresnel integrals

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Petr; Horváth, P.

    2012-01-01

    Roč. 29, č. 6 (2012), s. 1071-1077 ISSN 1084-7529 R&D Projects: GA MŠk(CZ) 1M06002; GA AV ČR KAN301370701 Institutional research plan: CEZ:AV0Z10100522 Keywords : Fresnel integrals * Fresnel diffraction Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.665, year: 2012

  4. Study of a spur gear dynamic behavior in transient regime

    Science.gov (United States)

    Khabou, M. T.; Bouchaala, N.; Chaari, F.; Fakhfakh, T.; Haddar, M.

    2011-11-01

    In this paper the dynamic behavior of a single stage spur gear reducer in transient regime is studied. Dynamic response of the single stage spur gear reducer is investigated at different rotating velocities. First, gear excitation is induced by the motor torque and load variation in addition to the fluctuation of meshing stiffness due to the variation of input rotational speed. Then, the dynamic response is computed using the Newmark method. After that, a parameter study is made on spur gear powered in the first place by an electric motor and in the second place by four strokes four cylinders diesel engine. Dynamic responses come to confirm a significant influence of the transient regime on the dynamic behavior of a gear set, particularly in the case of engine acyclism condition.

  5. Study of the Transition Flow Regime using Monte Carlo Methods

    Science.gov (United States)

    Hassan, H. A.

    1999-01-01

    This NASA Cooperative Agreement presents a study of the Transition Flow Regime Using Monte Carlo Methods. The topics included in this final report are: 1) New Direct Simulation Monte Carlo (DSMC) procedures; 2) The DS3W and DS2A Programs; 3) Papers presented; 4) Miscellaneous Applications and Program Modifications; 5) Solution of Transitional Wake Flows at Mach 10; and 6) Turbulence Modeling of Shock-Dominated Fows with a k-Enstrophy Formulation.

  6. A computational study of operating regimes for poloidal divertors

    International Nuclear Information System (INIS)

    Petravic, M.; Heifetz, D.; Post, D.

    1982-01-01

    We have identified three theoretical operating regimes for poloidal divertors. These regimes are determined by the geometry of the divertor and the input energy and particle fluxes, and are characterized by the divertor plasma density and temperature. A fully self-consistent two-dimensional model for the plasma and neutral atom and molecule transport was used to study poloidal divertor operation. Extensions of our previous calculations important to this study were the inclusion of parallel electron and ion thermal conduction. We find that the key physics in divertor operation is the neutral recycling near the neutralizer plate. This can be parametrized by R = GAMMAsub(P)/GAMMAsub(O), the ratio of particle flux striking the neutralizer plate to the particle flux entering the divertor. Values of R approx. equal to 1 can be produced by large pumping rates near the neutralizer plates resulting in low neutral recycling and a high temperature, low density divertor plasma. By decreasing the pumping near the neutralizer plate, R can be raised to an intermediate value of 5-10, the plasma temperature lowered by the same factor, and the density raised by a factor of 10-30. In this regime, escape of the neutrals back to the main plasma is virtually blocked. By further restricting the pumping, R can be raised to twenty or more, thereby lowering the temperature by a factor of twenty or more and raising the density by a factor of ninety or more. Such high density regimes have been observed on D-III and appear to offer the most promise for impurity control and particle control on large reactor experiments such as INTOR or FED. In this paper, we explore the range 3 < R < 16. (orig.)

  7. Studies of quantum dots in the quantum Hall regime

    Science.gov (United States)

    Goldmann, Eyal

    We present two studies of quantum dots in the quantum Hall regime. In the first study, presented in Chapter 3, we investigate the edge reconstruction phenomenon believed to occur when the quantum dot filling fraction is n≲1 . Our approach involves the examination of large dots (≤40 electrons) using a partial diagonalization technique in which the occupancies of the deep interior orbitals are frozen. To interpret the results of this calculation, we evaluate the overlap between the diagonalized ground state and a set of trial wavefunctions which we call projected necklace (PN) states. A PN state is simply the angular momentum projection of a maximum density droplet surrounded by a ring of localized electrons. Our calculations reveal that PN states have up to 99% overlap with the diagonalized ground states, and are lower in energy than the states identified in Chamon and Wen's study of the edge reconstruction. In the second study, presented in Chapter 4, we investigate quantum dots in the fractional quantum Hall regime using a Hartree formulation of composite fermion theory. We find that under appropriate conditions, the chemical potential of the dots oscillates periodically with B due to the transfer of composite fermions between quasi-Landau bands. This effect is analogous the addition spectrum oscillations which occur in quantum dots in the integer quantum Hall regime. Period f0 oscillations are found in sharply confined dots with filling factors nu = 2/5 and nu = 2/3. Period 3 f0 oscillations are found in a parabolically confined nu = 2/5 dot. More generally, we argue that the oscillation period of dots with band pinning should vary continuously with B, whereas the period of dots without band pinning is f0 .

  8. Astrophysical targets of the Fresnel diffractive imager

    Science.gov (United States)

    Koechlin, L.; Deba, P.; Raksasataya, T.

    2017-11-01

    The Fresnel Diffractive imager is an innovative concept of distributed space telescope, for high resolution (milli arc-seconds) spectro-imaging in the IR, visible and UV domains. This paper presents its optical principle and the science that can be done on potential astrophysical targets. The novelty lies in the primary optics: a binary Fresnel array, akin to a binary Fresnel zone plate. The main interest of this approach is the relaxed manufacturing and positioning constraints. While having the resolution and imaging capabilities of lens or mirrors of equivalent size, no optical material is involved in the focusing process: just vacuum. A Fresnel array consists of millions void subapertures punched into a large and thin opaque membrane, that focus light by diffraction into a compact and highly contrasted image. The positioning law of the aperture edges drives the image quality and contrast. This optical concept allows larger and lighter apertures than solid state optics, aiming to high angular resolution and high dynamic range imaging, in particular for UV applications. Diffraction focusing implies very long focal distances, up to dozens of kilometers, which requires at least a two-vessel formation flying in space. The first spacecraft, "the Fresnel Array spacecraft", holds the large punched foil: the Fresnel Array. The second, the "Receiver spacecraft" holds the field optics and focal instrumentation. A chromatism correction feature enables moderately large (20%) relative wavebands, and fields of a few to a dozen arc seconds. This Fresnel imager is adapted to high contrast stellar environments: dust disks, close companions and (we hope) exoplanets. Specific to the particular grid-like pattern of the primary focusing zone plate, is the very high dynamic range achieved in the images, in the case of compact objects. Large stellar photospheres may also be mapped with Fresnel arrays of a few meters opertaing in the UV. Larger and more complex fields can be imaged with

  9. 21 CFR 886.1390 - Flexible diagnostic Fresnel lens.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Flexible diagnostic Fresnel lens. 886.1390 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1390 Flexible diagnostic Fresnel lens. (a) Identification. A flexible diagnostic Fresnel lens is a device that is a very thin lens which has...

  10. Numerical study of flame structure in the mild combustion regime

    Directory of Open Access Journals (Sweden)

    Mardani Amir

    2015-01-01

    Full Text Available In this paper, turbulent non-premixed CH4+H2 jet flame issuing into a hot and diluted co-flow air is studied numerically. This flame is under condition of the moderate or intense low-oxygen dilution (MILD combustion regime and related to published experimental data. The modelling is carried out using the EDC model to describe turbulence-chemistry interaction. The DRM-22 reduced mechanism and the GRI2.11 full mechanism are used to represent the chemical reactions of H2/methane jet flame. The flame structure for various O2 levels and jet Reynolds numbers are investigated. The results show that the flame entrainment increases by a decrease in O2 concentration at air side or jet Reynolds number. Local extinction is seen in the upstream and close to the fuel injection nozzle at the shear layer. It leads to the higher flame entertainment in MILD regime. The turbulence kinetic energy decay at centre line of jet decreases by an increase in O2 concentration at hot Co-flow. Also, increase in jet Reynolds or O2 level increases the mixing rate and rate of reactions.

  11. Applications of the fresnel diffraction of neutrons

    International Nuclear Information System (INIS)

    Klein, A.G.; Opat, G.I.

    1978-01-01

    The place of Fresnel diffraction in the overall scheme of neutron interference experiments is outlined and possible applications are discussed in the areas of: magnetic domain visualisation; measurement of nuclear scattering lengths with very small specimens; focussing of long wavelength neutron beams using zone plates

  12. Applications of the Fresnel diffraction of neutrons

    International Nuclear Information System (INIS)

    Klein, A.G.; Opat, G.I.

    1978-01-01

    The place of Fresnel diffraction in the overall scheme of neutron interference experiments is outlined and possible applications are discussed in the areas of: magnetic domain visualisation; measurement of nuclear scattering lengths with very small specimens; focussing of long wavelength neutron beams using zone plates

  13. Performance comparison of four kinds of flat nonimaging Fresnel lenses made of polycarbonates and polymethyl methacrylate for concentrated photovoltaics.

    Science.gov (United States)

    Languy, Fabian; Habraken, Serge

    2011-07-15

    Solar concentrators made of a single refractive primary optics are limited to a concentration ratio of about 1000× [Opt. Express 19, A280 (2011)], due only to longitudinal chromatic aberration, while mirrors are limited to ∼46,000× by the angular size of the Sun. To reduce the chromatic aberration while keeping cost-effective systems for concentrated photovoltaics, a study of four different kinds of flat Fresnel doublets made of polycarbonates and polymethyl methacrylate is presented. It reveals that Fresnel doublets may have fewer optical losses than non-Fresnel doublets, with a lower lateral chromatic split allowing for even higher concentration ratio. © 2011 Optical Society of America

  14. Study of transitory regimes in hydraulic cooling circuits

    International Nuclear Information System (INIS)

    Bonnin, Jacques; Fanelli, Michel.

    1975-01-01

    The problem of transient regimes operated voluntary or not in hydraulic circuits is posed and the risks they cause are shown. As for the case of coolant flow loss the various methods for studying the problem are examined: numerical simulation (explicit and implicit), physical model, on-site testing. The numerical methods that not yet fully satisfying or economic, are still very badly representative for hollow closures. Physical models, expensive in the case of a first facility, are not still fully representative (inconsistent similitudes, difficulties in pump picturing). Site test recordings are often a trouble for exploitation and always limited to nondestructive tests. Comparison between the three methods, already satisfying, will have to be improved to allow remedies to the over pressures due to the transients to be developed [fr

  15. Experimental study on the unstable direct contact condensation regimes

    International Nuclear Information System (INIS)

    Damasio, C.; Del Tin, G.; Fiegna, G.; Malandrone, M.

    1985-01-01

    Vapour-liquid interface fluctuation frequencies have been measured by means of electrical resistive probes. Frequency data from these probes have been compared with measured frequencies from a Kistler piezoelectric pressure transducer in the pool near the steam-water interaction region. An attempt has been made to correlate measured frequencies to the observed condensation regimes. Experimental data concerning ''steam chugging'' and condensation oscillation regimes have been correlated in terms of dimensionless parameters

  16. Progress In Fresnel-Köhler Concentrators

    Science.gov (United States)

    Mohedano, Rubén; Cvetković, Aleksandra; Benítez, Pablo; Chaves, Julio; Miñano, Juan C.; Zamora, Pablo; Hernandez, Maikel; Vilaplana, Juan

    2011-12-01

    The Fresnel Köhler (FK) concentrator was first presented in 2008. Since then, various CPV companies have adopted this technology as base for their future commercial product. The key for this rapid penetration is a mixture of simplicity (the FK is essentially a Fresnel lens concentrator, a technology that dominates the market) and excellent performance: high concentration without giving up large manufacturing/aiming tolerances, enabling high efficiency even at the array level. All these features together have a great potential to lower energy costs. This work shows recent results and progress regarding this device, covering new design features, measurements and tests along with first performance achievements at the array level (pilot 6.5 Kwp plant). The work also discusses the potential impact of the FK enhanced performance on the Levelized Cost Of Electricity (LCOE).

  17. Numerical calculation of the Fresnel transform.

    Science.gov (United States)

    Kelly, Damien P

    2014-04-01

    In this paper, we address the problem of calculating Fresnel diffraction integrals using a finite number of uniformly spaced samples. General and simple sampling rules of thumb are derived that allow the user to calculate the distribution for any propagation distance. It is shown how these rules can be extended to fast-Fourier-transform-based algorithms to increase calculation efficiency. A comparison with other theoretical approaches is made.

  18. ZEROES OF GENERALIZED FRESNEL COMPLEMENTARY INTEGRAL FUNCTIONS

    Directory of Open Access Journals (Sweden)

    Jaime Lobo Segura

    2016-08-01

    Full Text Available Theoretical upper and lower bounds are established for zeroes of a parametric family of functions which are defined by integrals of the same type as the Fresnel complementary integral. Asymptotic properties for these bounds are obtained as well as monotony properties of the localization intervals. Given the value of the parameter an analytical-numerical procedure is deduced to enclose all zeros of a given function with an a priori error.

  19. On the Fresnel sine integral and the convolution

    Directory of Open Access Journals (Sweden)

    Adem Kılıçman

    2003-01-01

    Full Text Available The Fresnel sine integral S(x, the Fresnel cosine integral C(x, and the associated functions S+(x, S−(x, C+(x, and C−(x are defined as locally summable functions on the real line. Some convolutions and neutrix convolutions of the Fresnel sine integral and its associated functions with x+r, xr are evaluated.

  20. Development of Fresnel lens for improvement of rear visibility; Shikai kojo Fresnel lens no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Iwamoto, K; Sanada, C; Tsukino, M [Nissan Motor Co. Ltd., Tokyo (Japan)

    1997-10-01

    Fresnel lenses have been widely used to increase the visual field around vehicles for drivers. However, internal reflection in these lenses has been an obstacle in producing dear images. This internal glow is generated by incident light from an unexpected direction reflecting on the non-lens surface or radiating from the non-lens surface of the Fresnel lens. The cause of internal glow has been made dear combining louver film with the lens. The newly developed technology removes obstacles in producing dear images by reducing internal glow. 7 figs.

  1. Regime-switching models to study psychological process

    NARCIS (Netherlands)

    Hamaker, E.L.; Grasman, R.P.P.P.; Kamphuis, J.H.

    2010-01-01

    Many psychological processes are characterized by recurrent shifts between different states. To model these processes at the level of the individual, regime-switching models may prove useful. In this chapter we discuss two of these models: the threshold autoregressive model and the Markov

  2. Stochastic techno-economic assessment based on Monte Carlo simulation and the Response Surface Methodology: The case of an innovative linear Fresnel CSP (concentrated solar power) system

    International Nuclear Information System (INIS)

    Bendato, Ilaria; Cassettari, Lucia; Mosca, Marco; Mosca, Roberto

    2016-01-01

    Combining technological solutions with investment profitability is a critical aspect in designing both traditional and innovative renewable power plants. Often, the introduction of new advanced-design solutions, although technically interesting, does not generate adequate revenue to justify their utilization. In this study, an innovative methodology is developed that aims to satisfy both targets. On the one hand, considering all of the feasible plant configurations, it allows the analysis of the investment in a stochastic regime using the Monte Carlo method. On the other hand, the impact of every technical solution on the economic performance indicators can be measured by using regression meta-models built according to the theory of Response Surface Methodology. This approach enables the design of a plant configuration that generates the best economic return over the entire life cycle of the plant. This paper illustrates an application of the proposed methodology to the evaluation of design solutions using an innovative linear Fresnel Concentrated Solar Power system. - Highlights: • A stochastic methodology for solar plants investment evaluation. • Study of the impact of new technologies on the investment results. • Application to an innovative linear Fresnel CSP system. • A particular application of Monte Carlo simulation and response surface methodology.

  3. Linear Fresnel Spectrometer Chip with Gradient Line Grating

    Science.gov (United States)

    Choi, Sang Hyouk (Inventor); Park, Yeonjoon (Inventor)

    2015-01-01

    A spectrometer that includes a grating that disperses light via Fresnel diffraction according to wavelength onto a sensing area that coincides with an optical axis plane of the grating. The sensing area detects the dispersed light and measures the light intensity associated with each wavelength of the light. Because the spectrometer utilizes Fresnel diffraction, it can be miniaturized and packaged as an integrated circuit.

  4. Terahertz wave tomographic imaging with a Fresnel lens

    Institute of Scientific and Technical Information of China (English)

    S. Wang; X.-C. Zhang

    2003-01-01

    We demonstrate three-dimensional tomographic imaging using a Fresnel lens with broadband terahertz pulses. Objects at various locations along the beam propagation path are uniquely imaged on the same imaging plane using a Fresnel lens with different frequencies of the imaging beam. This procedure allows the reconstruction of an object's tomographic contrast image by assembling the frequency-dependent images.

  5. Adaption of optical Fresnel transform to optical Wigner transform

    International Nuclear Information System (INIS)

    Lv Cuihong; Fan Hongyi

    2010-01-01

    Enlightened by the algorithmic isomorphism between the rotation of the Wigner distribution function (WDF) and the αth fractional Fourier transform, we show that the optical Fresnel transform performed on the input through an ABCD system makes the output naturally adapting to the associated Wigner transform, i.e. there exists algorithmic isomorphism between ABCD transformation of the WDF and the optical Fresnel transform. We prove this adaption in the context of operator language. Both the single-mode and the two-mode Fresnel operators as the image of classical Fresnel transform are introduced in our discussions, while the two-mode Wigner operator in the entangled state representation is introduced for fitting the two-mode Fresnel operator.

  6. Characterizing snowmelt regime of the river swat - a case study

    International Nuclear Information System (INIS)

    Malik, M.A.

    2015-01-01

    Snowmelt generates 70 to 80% of runoff of Indus River and its tributaries. Forecasting snowmelt generated flow is important for water management, reservoir operation and channel diversion. River Swat being not direct contributor to the existing reservoirs remained out of focus for characterizing its snowmelt regime. Thirty years (1971-2000) data of upper Swat catchment above Kalam gauging station was acquired from WAPDA. Normal monthly values over the period and average monthly values of each year were determined for stream flow, precipitation and temperature together with average monthly values of weighted and maximum temperature. Snowmelt regime was ascertained from plot of normal values of flow, precipitation and temperature. Using temperature index approach, average monthly flow over the snowmelt months (April, May and June) in terms of mm depth over the catchment was regressed on all the temperature indices using exponential, power and third degree polynomial functions. Tmax was found the best index for snowmelt with R2 as 0.902 for the third degree polynomial function. Runoff coefficient (ROC) for the total precipitation was conceptualized and through iteration was found as T max 100. The optimized value of ROC was used to segregate rain induced and snowmelt induced runoff. The segregated snowmelt induced runoff was again regressed on Tmax using the same function which slightly improved R2 to 0.916. The model was tested for four years of data and forecasted flow was found reasonable in the context of simplicity of the approach. (author)

  7. Performance investigation of a concentrating photovoltaic/thermal system with transmissive Fresnel solar concentrator

    International Nuclear Information System (INIS)

    Feng, Chaoqing; Zheng, Hongfei; Wang, Rui; Ma, Xinglong

    2016-01-01

    Highlights: • A common design method of a cycloidal transmissive Fresnel solar concentrator was presented. • The gallium arsenide high concentrated solar was used as the receiver. • High efficiency of electric generating could be achieved at noon. • Fresnel solar concentrator was studied and compared in hazy weather and clear weather. - Abstract: A design method of a cycloidal transmissive Fresnel solar concentrator which can provide a certain width focal line was presented in this study. Based on the optical principle of refraction, the dimensions of each wedge-shaped element of Fresnel lens are calculated. An optical simulation has been done to obtain the optical efficiency of the concentrator for different tracking error and axial incidence angle. It has been found that about 80% of the incident sunlight can still be gathered by the absorber when the tracking error is within 0.7°. When the axial angle of incidence is within 10°, it almost has no influence to the receiving rate. The concentrating photovoltaic/thermal system with transmissive Fresnel solar concentrator has been designed in this paper. Take the gallium arsenide high concentrated battery as the receiver, experimental research about cylindrical Fresnel concentrating photovoltaic/thermal system is undertaken in the real sky. Main parameters are tested such as the temperature distribution on receiver, electric energy and thermal energy outputs of concentrating photovoltaic/thermal system, the efficiency of multipurpose utilization of electric and heat, and so on. The test results in clear weather show that maximum electric generating efficiency is about 18% at noon, the maximum heat receiving rate of cooling water is about 45%. At noon time (11:00–13:00), the total efficiency of thermal and electricity can reach more than 55%. Performance of this concentrating photovoltaic/thermal system with transmissive Fresnel solar concentrator is studied and compared in two types typical weather, hazy

  8. Development of background reduced Fresnel phase zone plate

    International Nuclear Information System (INIS)

    Tamari, Yohei; Azechi, Hiroshi

    2004-01-01

    In study of hot and dense plasma, a high spatial resolution (a few microns) x-ray imaging is very important to observe these plasmas. The Fresnel phase zone plate (FPZP) consists of alternately material and transparent circular annuli placed concentrically, which image x rays using diffraction x rays from all annuli. FPZP have imaged 4.7-4.77 keV x rays with 2.2 μm spatial resolution. However FPZP has a problem that background level is comparable to signal level. In subtraction of background, the error of 10% is caused. For the accurate background subtraction, we designed new FPZP, which consist of three β layers of a transparent zone and two material zones. The new design FPZP parameters (thickness of material zones, each zone width) have been optimized, and in that optimum design signal-to-background ratio is 4 times better than conventional two layers FPZP

  9. Novel optical scanning cryptography using Fresnel telescope imaging.

    Science.gov (United States)

    Yan, Aimin; Sun, Jianfeng; Hu, Zhijuan; Zhang, Jingtao; Liu, Liren

    2015-07-13

    We propose a new method called modified optical scanning cryptography using Fresnel telescope imaging technique for encryption and decryption of remote objects. An image or object can be optically encrypted on the fly by Fresnel telescope scanning system together with an encryption key. For image decryption, the encrypted signals are received and processed with an optical coherent heterodyne detection system. The proposed method has strong performance through use of secure Fresnel telescope scanning with orthogonal polarized beams and efficient all-optical information processing. The validity of the proposed method is demonstrated by numerical simulations and experimental results.

  10. Using biofuel tracers to study alternative combustion regimes

    International Nuclear Information System (INIS)

    Mack, J.H.; Flowers, D.L.; Buchholz, B.A.; Dibble, R.W.

    2007-01-01

    Interest in the use of alternative fuels and engines is increasing as the price of petroleum climbs. The inherently higher efficiency of Diesel engines has led to increased adoption of Diesels in Europe, capturing approximately 40% of the new passenger car market. Unfortunately, lower CO 2 emissions are countered with higher nitrogen oxides (NO x ) and particulate matter (PM) emissions and higher noise. Adding oxygenated compounds to the fuel helps reduce PM emissions. However, relying on fuel alone to reduce PM is unrealistic due to economic constraints and difficult due to the emerging PM standards. Keeping peak combustion temperature below 1700 K inhibits NO x formation. Altering the combustion regime to burn at temperatures below the NO x threshold and accept a wide variety of fuels seems like a promising alternative for future engines. Homogeneous charge compression ignition (HCCI) is a possible solution. Fuel and air are well mixed prior to intake into a cylinder (homogeneous charge) and ignition occurs by compression of the fuel-air mixture by the piston. HCCI is rapid and relatively cool, producing little NO x and PM. Unfortunately, it is hard to control since HCCI is initiated by temperature and pressure instead of a spark or direct fuel injection. We investigate biofuel HCCI combustion, and use intrinsically labeled biofuels as tracers of HCCI combustion. Data from tracer experiments are used to improve our combustion modeling

  11. Earth Regimes Network Evolution Study (ERNESt): Introducing the Space Mobile Network

    Science.gov (United States)

    Menrad, Bob

    2016-01-01

    Speaker and Presenter at the Lincoln Laboratory Communications Workshop on April 5, 2016 at the Massachusetts Institute of Technology Lincoln Laboratory in Lexington, MA. A visual presentation titled Earth Regimes Network Evolution Study (ERNESt).

  12. Bragg-Fresnel optics: New field of applications

    Energy Technology Data Exchange (ETDEWEB)

    Snigirev, A. [ESRF, Grenoble (France)

    1997-02-01

    Bragg-Fresnel Optics shows excellent compatibility with the third generation synchrotron radiation sources such as ESRF and is capable of obtaining monochromatic submicron focal spots with 10{sup 8}-10{sup 9} photons/sec in an energy bandwidth of 10{sup -4}-10{sup -6} and in a photon energy range between 2-100 keV. New types of Bragg-Fresnel lenses like modified, ion implanted, bent and acoustically modulated were tested. Microprobe techniques like microdiffraction and microfluorescence based on Bragg-Fresnel optics were realised at the ESRF beamlines. Excellent parameters of the X-ray beam at the ESRF in terms of low emittance and quite small angular source size allow for Bragg-Fresnel optics to occupy new fields of applications such as high resolution diffraction, holography, interferometry and phase contrast imaging.

  13. Prediction of subsurface fracture in mining zone of Papua using passive seismic tomography based on Fresnel zone

    Energy Technology Data Exchange (ETDEWEB)

    Setiadi, Herlan; Nurhandoko, Bagus Endar B.; Wely, Woen [WISFIR Lab., Physics of Complex System, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Bandung 40132 (Indonesia); Riyanto, Erwin [PT Freeport Indonesia, Tembagapura, Indonesia herlansetiadi@yahoo.com (Indonesia)

    2015-04-16

    Fracture prediction in a block cave of underground mine is very important to monitor the structure of the fracture that can be harmful to the mining activities. Many methods can be used to obtain such information, such as TDR (Time Domain Relectometry) and open hole. Both of them have limitations in range measurement. Passive seismic tomography is one of the subsurface imaging method. It has advantage in terms of measurements, cost, and rich of rock physical information. This passive seismic tomography studies using Fresnel zone to model the wavepath by using frequency parameter. Fresnel zone was developed by Nurhandoko in 2000. The result of this study is tomography of P and S wave velocity which can predict position of fracture. The study also attempted to use sum of the wavefronts to obtain position and time of seismic event occurence. Fresnel zone tomography and the summation wavefront can predict location of geological structure of mine area as well.

  14. Study on flow regimes of high-pressure and dense-phase pneumatic conveying

    International Nuclear Information System (INIS)

    Lu Peng; Chen Xiaoping; Liang Cai; Pu Wenhao; Zhou Yun; Xu Pan; Zhao Changsui

    2009-01-01

    High-pressure and dense-phase pneumatic conveying of pulverized coal is a key technology in the field of large-scale entrained bed coal gasification. Flow regime plays an important role in two-phase flow because it affects not only flow behavior and safety operation, but also the reliability of practical processes. Few references and experiences in high-pressure and dense-phase conveying are available, especially for the flow regimes. And because of the high stickiness and electrostatic attraction of pulverized coal to the pipe wall, it is very difficult to make out the flow regimes in the conveying pipe by visualization method. Thus quartz powder was chosen as the conveyed material to study the flow regime. High-speed digital video camera was employed to photograph the flow patterns. Experiments were conducted on a pilot scale experimental setup at the pressure up to 3.6MPa. With the decrease in superficial gas velocity, three distinguishable flow regimes were observed: stratified flow, dune flow and plug flow. The characteristics of pressure traces acquired by high frequency response pressure transmitter and their EMD (Empirical Mode Decomposition) characteristics were correlated strongly with the flow regimes. Combining high-speed photography and pressure signal analysis together can make the recognition of flow patterns in the high-pressure and dense-phase pneumatic conveying system more accurate. The present work will lead to better understanding of the flow regime transition under high-pressure.

  15. Design of a nonimaging Fresnel lens for solar concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Leutz, R.; Akisawa, Atushi; Kashiwagi, Takao [Tokyo University of Agriculture and Technology (Japan). Dept. of Mechanical Systems Engineering; Suzuki, Akio [UNESCO, Paris (France)

    1999-04-01

    An optimum convex shaped nonimaging Fresnel lens is designed following the edge ray principle. The lens is evaluated by tracing rays and calculating a projective optical concentration ratio. This Fresnel lens is intended for use in evacuated tube type solar concentrators, generating mid-temperature heat to drive sorption cycles, or provide industrial process heat. It can also be used along with a secondary concentrator in photovoltaic applications. (author)

  16. Signal-enhancement reflective pulse oximeter with Fresnel lens

    Science.gov (United States)

    Chung, Shuang-Chao; Sun, Ching-Cherng

    2016-09-01

    In this paper, a new reflective pulse oximeter is proposed and demonstrated with implanting a Fresnel lens, which enhances the reflected signal. An optical simulation model incorporated with human skin characteristics is presented to evaluate the capability of the Fresnel lens. In addition, the distance between the light emitting diode and the photodiode is optimized. Compared with the other reflective oximeters, the reflected signal light detected by the photodiode is enhanced to more than 140%.

  17. Optical modeling of Fresnel zoneplate microscopes

    International Nuclear Information System (INIS)

    Naulleau, Patrick P.; Mochi, Iacopo; Goldberg, Kenneth A.

    2011-01-01

    Defect free masks remain one of the most significant challenges facing the commercialization of extreme ultraviolet (EUV) lithography. Progress on this front requires high-performance wavelength-specific metrology of EUV masks, including high-resolution and aerial-image microscopy performed near the 13.5 nm wavelength. Arguably the most cost-effective and rapid path to proliferating this capability is through the development of Fresnel zoneplate-based microscopes. Given the relative obscurity of such systems, however, modeling tools are not necessarily optimized to deal with them and their imaging properties are poorly understood. Here we present a modeling methodology to analyze zoneplate microscopes based on commercially available optical modeling software and use the technique to investigate the imaging performance of an off-axis EUV microscope design. The modeling predicts that superior performance can be achieved by tilting the zoneplate, making it perpendicular to the chief ray at the center of the field, while designing the zoneplate to explicitly work in that tilted plane. Although the examples presented here are in the realm of EUV mask inspection, the methods described and analysis results are broadly applicable to zoneplate microscopes in general, including full-field soft-x-ray microscopes routinely used in the synchrotron community.

  18. Diffraction patterns in Fresnel approximation of periodic objects for a colorimeter of two apertures

    Science.gov (United States)

    Cortes-Reynoso, Jose-German R.; Suarez-Romero, Jose G.; Hurtado-Ramos, Juan B.; Tepichin-Rodriguez, Eduardo; Solorio-Leyva, Juan Carlos

    2004-10-01

    In this work, we present a study of Fresnel diffraction of periodic structures in an optical system of two apertures. This system of two apertures was used successfully for measuring color in textile samples solving the problems of illumination and directionality that present current commercial equipments. However, the system is sensible to the spatial frequency of the periodic sample"s area enclosed in its optical field of view. The study of Fresnel diffraction allows us to establish criteria for geometrical parameters of measurements in order to assure invariance in angular rotations and spatial positions. In this work, we use the theory of partial coherence to calculate the diffraction through two continuous apertures. In the calculation process, we use the concept of point-spread function of the system for partial coherence, in this way we avoid complicated statistical processes commonly used in the partial coherence theory.

  19. A Study on the cooperation policy in multilateral nuclear control regimes and the advancing of national export control system

    International Nuclear Information System (INIS)

    Lee, Byung Wook; Oh, K. B.; Yang, M. H.; Lee, H. M.; Lee, K. S.; Ko, H. S.; Ryu, J. S.; Kim, J. S.

    2004-08-01

    This study carried out the analysis of trends of the multilateral nuclear control in four aspects. First, this study analyzes the past trends of the international nuclear non-proliferation regime, which includes the NPT, the IAEA safeguards system, the international nuclear export control regime and the physical protection of nuclear materials. Second, this study establishes the multilateral cooperation strategies for the effective cooperation in the process of strengthening the nuclear control regimes. Third, this study reviews the major agenda of nuclear control regimes and establishes national positions on each agenda. Fourth, this study also analyzes outstanding issues in nuclear control regimes and derives some factors to reflect national nuclear control system

  20. Profile control studies for JET optimised shear regime

    Energy Technology Data Exchange (ETDEWEB)

    Litaudon, X.; Becoulet, A.; Eriksson, L.G.; Fuchs, V.; Huysmans, G.; How, J.; Moreau, D.; Rochard, F.; Tresset, G.; Zwingmann, W. [Association Euratom-CEA, CEA/Cadarache, Dept. de Recherches sur la Fusion Controlee, DRFC, 13 - Saint-Paul-lez-Durance (France); Bayetti, P.; Joffrin, E.; Maget, P.; Mayorat, M.L.; Mazon, D.; Sarazin, Y. [JET Abingdon, Oxfordshire (United Kingdom); Voitsekhovitch, I. [Universite de Provence, LPIIM, Aix-Marseille 1, 13 (France)

    2000-03-01

    This report summarises the profile control studies, i.e. preparation and analysis of JET Optimised Shear plasmas, carried out during the year 1999 within the framework of the Task-Agreement (RF/CEA/02) between JET and the Association Euratom-CEA/Cadarache. We report on our participation in the preparation of the JET Optimised Shear experiments together with their comprehensive analyses and the modelling. Emphasis is put on the various aspects of pressure profile control (core and edge pressure) together with detailed studies of current profile control by non-inductive means, in the prospects of achieving steady, high performance, Optimised Shear plasmas. (authors)

  1. Thyroid scintigraphy using coded apertures derived from a complex Fresnel zone plate

    International Nuclear Information System (INIS)

    Meinke, J.

    1986-01-01

    Comparative evaluations of conventional scintiscanning and Fresnel zone plate imaging carried out in the thyroid for the purposes of this study showed that the purported benefits of the latter technique were confirmed by phantoms but did to a lesser extent bear out in patients. Major drawbacks are the lack of additional information of clinical relevance, the greater length of time needed and the difficult interpretation of artefacts. (TRV) [de

  2. Study of dissipation in superconductors at high frequency regime

    International Nuclear Information System (INIS)

    Vallet, Christophe

    1994-01-01

    This thesis is devoted to the study of the Joule effect dissipation occurring in superconducting accelerating cavities. Two mechanisms of dissipation are presented: the first concerns the magnetic flux present around the cryostat and trapped by the (Niobium) superconducting cavity during a temperature descent; a theoretical and experimental study allow the evaluation of the percentage of flux which rests trapped and its contribution to the dissipation. Improving the magnetic shielding leads to a remnant field of the order of several milli-Gauss and the surface resistance drops from 25 nΩ to 4.2 nΩ (with a few other modifications). The second mechanism is related to the polycrystalline structure of the superconductor. A theoretical study evaluates this contribution to about 3 nΩ. A complex process of recrystallization is needed in order to overcome this effect. Using an electron beam at low energy might help in reaching this goal and thus observing surface resistance values smaller than ever obtained. (author) [fr

  3. Development of a Fresnel lens for cold neutrons based on neutron refractive optics

    International Nuclear Information System (INIS)

    Oku, T.; Morita, S.; Moriyasu, S.; Yamagata, Y.; Ohmori, H.; Takizawa, Y.; Shimizu, H.M.; Hirota, T.; Kiyanagi, Y.; Ino, T.; Furusaka, M.; Suzuki, J.

    2001-01-01

    We have developed compound refractive lenses (CRLs) for cold neutrons, which are made of vitreous silica and have an effective potential of (90.1-2.7x10 -4 i) neV. In the case of compound refractive optics, neutron absorption by the material deteriorates lens performance. Thus, to prevent an increase in neutron absorption with increasing beam size, we have developed Fresnel lenses using the electrolytic in-process dressing grinding technique. The lens characteristics were carefully investigated with experimental and numerical simulation studies. The lenses functioned as a neutron focusing lens, and the focal length of 14 m was obtained with a 44-element series of the Fresnel lenses for 10 A neutrons. Moreover, good neutron transmission of 0.65 for 15 A neutrons was obtained due to the shape effect. According to comprehensive analysis of the obtained results, it is possible to realize a CRL for practical use by choosing a suitable lens shape and material

  4. Analytical analysis of solar thermal collector with glass and Fresnel lens glazing

    Science.gov (United States)

    Zulkifle, Idris; Ruslan, Mohd Hafidz Hj; Othman, Mohd Yusof Hj; Ibarahim, Zahari

    2018-04-01

    Solar thermal collector is a system that converts solar radiation to heat. The heat will raise the temperature higher than the ambient temperature. Absorber and glazing are two important components in order to increase the temperature of the collector. The thermal absorber will release heat by convection and as radiation to the surrounding. These losses will be reduced by glazing. Other than that, glazing is beneficial for protecting the collector from dust and water. This study discusses about modelling of solar thermal collector effects of different mass flow rates with different glazing for V-groove flat plate solar collectors. The glazing used was the glass and linear Fresnel lens. Concentration ratio in this modelling was 1.3 for 0.1m solar collector thickness. Results show that solar collectors with linear Fresnel lens has the highest efficiency value of 71.18% compared to solar collectors with glass which has efficiency 54.10% with same operation conditions.

  5. A COMPARATIVE CLINICAL STUDY OF DHAKA AND PRITCHARD REGIME IN THE ECLAMPSIA MANAGEMENT

    Directory of Open Access Journals (Sweden)

    Sunanda Bai

    2015-08-01

    Full Text Available INTRODUCTION : The safety and efficacy of low dose Magnesium Sulphate regime in the management of Antepartum / Intrapartum / Postpartum eclampsia patients. METHODS : This study was conducted at Bowring and Ladycurzon Hospital in the Department of Obstetrics and Gynaecology BMCRI Bengaluru during the period of April 2013 to April 2014 100 eclampsia patients including antepartum eclampsia, intrapartum eclampsia, post - partum eclampsia were included for the purpose of this study. Magnesium Sulphate was used for the management of eclampsia. 50 eclamptic patients were treated with Pritchard regimen and other 50 with Dhaka regimen. Hypertension is treated with antihypertensive drugs. A detailed history, examination was done. In the present study 25 patients were below 20 years. In the study group 26 patients were between 28 to 37 weeks. 18 were more than 37 weeks. 6 patients were below 28 weeks. In patients treated under Pritchard regimen 44 were admitted in conscious state. Under Dhaka regimen 44 were conscious. In Dhaka regimen 28 patients had systolic BP above 161 mm Hg, under Pritchard 22 had systolic BP above 161 mm Hg. 18 Patients under Dhaka regimen had more than 110 mm Hg diastolic BP. In Pritchard regime 19 patients had diastolic BP more than 110 mm Hg. In patients treated with Dhaka regimen 26 underwent LSCS / Hysterectomy . In patients treated with Pritchard 26 were underwent LSCS. In Dhaka regimen 2 patients had abruption, 1 had HELLP and 5 had pulmonary edema. One patient developed occipital lobe infarct. In Pritchard regime 2 had abruption. 1 patient had HELLP and 2 had pulmonary edema. Out of the 100 patients, 98 were discharged from the hospital without any sequlae. 2 patients died due to complication of eclampsia. 10 perinatal death in Dhaka regime, 13 perinatal death in Pritchard regime. RESULTS : This present study compared the efficacy of low dose MgSO 4 with standard Pritchard regime. This study showed that recurrence of fits

  6. Flow Regime Classification and Hydrological Characterization: A Case Study of Ethiopian Rivers

    Directory of Open Access Journals (Sweden)

    Belete Berhanu

    2015-06-01

    Full Text Available The spatiotemporal variability of a stream flow due to the complex interaction of catchment attributes and rainfall induce complexity in hydrology. Researchers have been trying to address this complexity with a number of approaches; river flow regime is one of them. The flow regime can be quantified by means of hydrological indices characterizing five components: magnitude, frequency, duration, timing, and rate of change of flow. Similarly, this study aimed to understand the flow variability of Ethiopian Rivers using the observed daily flow data from 208 gauging stations in the country. With this process, the Hierarchical Ward Clustering method was implemented to group the streams into three flow regimes (1 ephemeral, (2 intermittent, and (3 perennial. Principal component analysis (PCA is also applied as the second multivariate analysis tool to identify dominant hydrological indices that cause the variability in the streams. The mean flow per unit catchment area (QmAR and Base flow index (BFI show an incremental trend with ephemeral, intermittent and perennial streams. Whereas the number of mean zero flow days ratio (ZFI and coefficient of variation (CV show a decreasing trend with ephemeral to perennial flow regimes. Finally, the streams in the three flow regimes were characterized with the mean and standard deviation of the hydrological variables and the shape, slope, and scale of the flow duration curve. Results of this study are the basis for further understanding of the ecohydrological processes of the river basins in Ethiopia.

  7. Electrically Tunable Binary-Phase Fresnel Lens Based on Polymer Dispersed Liquid Crystal

    Directory of Open Access Journals (Sweden)

    Hui LI

    2017-08-01

    Full Text Available This is a proposal for a Fresnel lens with an electrically tunable binary-phase made of polymer dispersed liquid crystal (PDLC, which has relatively fast response time and low applied voltage. Simple fabrication is the major advantage of the proposed method. In this study, NOA65 and E7 were utilized with weight ratios of 60 wt.%: 40 wt.%. There was also the utilization of a relatively low intensity UV-light, 0.53 mW/cm2. The duration time of exposure was about 30 hours. The performance improvement of the Fresnel lens resulted from the infiltration of large LC droplet into the PDLC film. The phenomenon of black cross strip patterns could be explained with the use of the electro-hydrodynamics theory. The diffraction efficiency of the proposed lens was from 31.1 % to 41 % with the changes of externally applied voltage. This work presents an effective approach to get relatively complete phase separation in PDLC. The proposed method also provides great potential in developing high performance Fresnel lens.DOI: http://dx.doi.org/10.5755/j01.ms.23.2.16317

  8. Studying the operational regimes of air-radiator coolers at the Bilibin NPP

    International Nuclear Information System (INIS)

    Gutsev, D.F.; Dembovskij, A.V.; Kuznetsov, R.K.; Lukashenko, Eh.M.; Morozov, S.K.; Soldatov, G.E.

    1985-01-01

    Results of experimental and calculational-theoretical studies of operational regimes of airradiator coolers at the Bilibin NPP are set out. For the first time dry fan towers are used there under the Far North conditions. Operational experience of the Forgo cooling towers under the above conditions is given. The mathematical model of monstationary heat transfer in a pipe heat exchanger ribbed with perforated plates is worked out for numerical analysis of the tower operational regimes. The results of studies point out the ways for improvement of the cooling towers and their operational conditions

  9. Characterising the hydrological regime of an ungauged temporary river system: a case study.

    Science.gov (United States)

    D'Ambrosio, Ersilia; De Girolamo, Anna Maria; Barca, Emanuele; Ielpo, Pierina; Rulli, Maria Cristina

    2017-06-01

    Temporary streams are characterised by specific hydrological regimes, which influence ecosystem processes, groundwater and surface water interactions, sediment regime, nutrient delivery, water quality and ecological status. This paper presents a methodology to characterise and classify the regime of a temporary river in Southern Italy based on hydrological indicators (HIs) computed with long-term daily flow records. By using a principal component analysis (PCA), a set of non-redundant indices were identified describing the main characteristics of the hydrological regime in the study area. The indicators identified were the annual maximum 30- and 90-day mean (DH4 and DH5), the number of zero flow days (DL6), flow permanence (MF) and the 6-month seasonal predictability of dry periods (SD6). A methodology was also tested to estimate selected HIs in ungauged river reaches. Watershed characteristics such as catchment area, gauging station elevation, mean watershed slope, mean annual rainfall, land use, soil hydraulic conductivity and available water content were derived for each site. Selected indicators were then linked to the catchment characteristics using a regression analysis. Finally, MF and SD6 were used to classify the river reaches on the basis of their degree of intermittency. The methodology presented in this paper constitutes a useful tool for ecologists and water resource managers in the Water Framework Directive implementation process, which requires a characterisation of the hydrological regime and a 'river type' classification for all water bodies.

  10. Fresnel's phase observation by means of the pinhole Young's experiment

    International Nuclear Information System (INIS)

    Medina, F.F.; Matteucci, G.

    2000-04-01

    Using the conventional Young's experiment with two pinholes, we observe the shift effect of the Fresnel's phase on the interference patterns, by measuring its intensity on the optical axis. It allows us to propose a criterion for distinguishing between Fraunhofer and Fresnel diffraction. Indeed, in the Fraunhofer domain the Young's patterns will be centered on the optical axis. As a consequence, only constructive interference will occur at this point. But in the Fresnel domain, the Young's patterns will be laterally shifted in such a way that constructive and destructive interference will occur alternatively on the optical axis, and the intensity of the diffraction pattern at this point will oscillate. Extended diffracting apertures can be analyzed as ensembles of Young's pairs of wavelet sources. From this point of view, the intensity distribution they produce on the detector plane results from the superposition of all their interference patterns. (author)

  11. Digital reconstruction of Young's fringes using Fresnel transformation

    Science.gov (United States)

    Kulenovic, Rudi; Song, Yaozu; Renninger, P.; Groll, Manfred

    1997-11-01

    This paper deals with the digital numerical reconstruction of Young's fringes from laser speckle photography by means of the Fresnel-transformation. The physical model of the optical reconstruction of a specklegram is a near-field Fresnel-diffraction phenomenon which can be mathematically described by the Fresnel-transformation. Therefore, the interference phenomena can be directly calculated by a microcomputer.If additional a CCD-camera is used for specklegram recording the measurement procedure and evaluation process can be completely carried out in a digital way. Compared with conventional laser speckle photography no holographic plates, no wet development process and no optical specklegram reconstruction are needed. These advantages reveal a wide future in scientific and engineering applications. The basic principle of the numerical reconstruction is described, the effects of experimental parameters of Young's fringes are analyzed and representative results are presented.

  12. Postoperative recovery profile after elective abdominal hysterectomy: a prospective, observational study of a multimodal anaesthetic regime

    DEFF Research Database (Denmark)

    Jensen, Kenneth; Kehlet, Henrik; Lund, Claus M

    2009-01-01

    insufficiency and time of discharge readiness. RESULTS: The structured regime consisting of total intravenous anaesthesia (propofol-remifentanil), well defined fluid administration, prophylactic antiemetics (dexamethasone, ondansetron, droperidol), weak analgesics (celecoxib, paracetamol) and intraoperative......BACKGROUND AND OBJECTIVE: To evaluate the applicability, effectiveness, immediate postoperative complaints and requirements for a postanaesthesia care unit stay after elective abdominal hysterectomy under a well defined, multimodal anaesthetic regime. METHODS: Observational study of 145 consecutive......, was seen in 52%. CONCLUSION: We conclude that a structured multimodal anaesthetic regime is feasible in daily clinical practice and advantageous, and that postoperative pain and oxygen requirements (to sustain an SpO2 >92%) are the major determinants for length of stay in the postanaesthesia care unit...

  13. Study of the Higgs-Yukawa theory in the strong-Yukawa coupling regime

    International Nuclear Information System (INIS)

    Bulava, John; Gerhold, Philipp; Nagy, Attila; Deutsches Elektronen-Synchrotron; Hou, George W.S.; Smigielski, Brian; Jansen, Karl; Knippschild, Bastian; Univ. of Mainz; Lin, David C.J.; National Centre of Theoretical Sciences, Hsinchu; Nagai, Kei-Ichi; Ogawa, Kenji

    2011-12-01

    In this article, we present an ongoing lattice study of the Higgs-Yukawa model, in the regime of strong-Yukawa coupling, using overlap fermions. We investigated the phase structure in this regime by computing the Higgs vacuum expectation value, and by exploring the finite-size scaling behaviour of the susceptibility corresponding to the magnetisation. Our preliminary results indicate the existence of a second-order phase transition when the Yukawa coupling becomes large enough, at which the Higgs vacuum expectation value vanishes and the susceptibility diverges. (orig.)

  14. Miniaturization of Fresnel lenses for solar concentration: a quantitative investigation.

    Science.gov (United States)

    Duerr, Fabian; Meuret, Youri; Thienpont, Hugo

    2010-04-20

    Sizing down the dimensions of solar concentrators for photovoltaic applications offers a number of promising advantages. It provides thinner modules and smaller solar cells, which reduces thermal issues. In this work a plane Fresnel lens design is introduced that is first analyzed with geometrical optics. Because of miniaturization, pure ray tracing may no longer be valid to determine the concentration performance. Therefore, a quantitative wave optical analysis of the miniaturization's influence on the obtained concentration performance is presented. This better quantitative understanding of the impact of diffraction in microstructured Fresnel lenses might help to optimize the design of several applications in nonimaging optics.

  15. The Fresnel Diffraction: A Story of Light and Darkness

    Science.gov (United States)

    Aime, C.; Aristidi, É.; Rabbia, Y.

    2013-03-01

    In a first part of the paper we give a simple introduction to the free space propagation of light at the level of a Master degree in Physics. The presentation promotes linear filtering aspects at the expense of fundamental physics. Following the Huygens-Fresnel approach, the propagation of the wave writes as a convolution relationship, the impulse response being a quadratic phase factor. We give the corresponding filter in the Fourier plane. As an illustration, we describe the propagation of wave with a spatial sinusoidal amplitude, introduce lenses as quadratic phase transmissions, discuss their Fourier transform properties and give some properties of Soret screens. Classical diffractions of rectangular diaphragms are also given here. In a second part of the paper, the presentation turns into the use of external occulters in coronagraphy for the detection of exoplanets and the study of the solar corona. Making use of Lommel series expansions, we obtain the analytical expression for the diffraction of a circular opaque screen, giving thereby the complete formalism for the Arago-Poisson spot. We include there shaped occulters. The paper ends up with a brief application to incoherent imaging in astronomy.

  16. Fresnel formulas for the forced electromagnetic pulses and their application for optical-to-terahertz conversion in nonlinear crystals.

    Science.gov (United States)

    Bakunov, M I; Maslov, A V; Bodrov, S B

    2007-11-16

    We show that the usual Fresnel formulas for a free-propagating pulse are not applicable for a forced terahertz electromagnetic pulse supported by an optical pulse at the end of a nonlinear crystal. The correct linear reflection and transmission coefficients that we derive show that such pulses can experience a gain or loss at the boundary. This energy change depends on linear dielectric constants only. We also predict a regime where a complete disappearance of the forced pulse under oblique incidence occurs, an effect that has no counterpart for free-propagating pulses.

  17. Numerical and experimental analysis of a point focus solar collector using high concentration imaging PMMA Fresnel lens

    International Nuclear Information System (INIS)

    Xie, W.T.; Dai, Y.J.; Wang, R.Z.

    2011-01-01

    Research highlights: → We studied a point focus Fresnel solar collector using different cavity receivers. → The collector heat removal factors are derived to find the optimal cavity shape. → Numerical and experimental analysis shows that the conical cavity is optimum. -- Abstract: A high concentration imaging Fresnel solar collector provided with different cavity receivers was developed and its behavior was investigated. Round copper pipes winded into different spring shapes were used as receiver by placing in the cylindrical cavity to absorb concentrated solar energy and transfer it to a heat transfer fluid (HTF). The collector efficiency factor and collector heat removal factor were derived for the cavity receivers to find out heat transfer mechanism and to propose an effective way for evaluating the performance of Fresnel solar collector and determining the optimal cavity structure. The problem of Fresnel solar collector with synthetic heat transfer oil flow was simulated and analyzed to investigate heat loss from different cavity receivers. Solar irradiation as well as convection and heat transfer in the circulating fluid and between the internal surfaces of the cavity and the environment are considered in the model. The temperature distribution over its area as well as the collector thermal efficiency at nominal flow rate was used in order to validate the simulation results. It was found that the simulated temperature distribution during operation and the average collector efficiency are in good agreement with the experimental data. Finally, the optimal shape of solar cavity receiver, as well as its thermal performance, are deeply analyzed and discussed.

  18. Political Regime and Learning Outcomes of Stakeholder Participation: Cross-National Study of 81 Biosphere Reserves

    Directory of Open Access Journals (Sweden)

    Alba Mohedano Roldán

    2017-04-01

    Full Text Available Stakeholder participation in natural resource management has spread widely, even to nondemocracies, driven by expectations of beneficial outcomes such as multidirectional learning. However, can we expect participation to be equally effective in achieving multidirectional learning in democracies and nondemocracies? Unsurprisingly, previous studies indicate the relevance of power distribution for learning. Higher levels of repression and accumulation of political capital in nondemocracies should limit the distribution of power across stakeholders. Yet, the relationship between political regime, participation, and learning has rarely been studied empirically. I address this gap by analysing multidirectional learning in stakeholder participation in 81 Man and the Biosphere reserves across 35 countries using ordinary least squares regression, Firth logistic regression, and heat maps. The results suggest that the amount of stakeholders sharing knowledge and learning is similar in both regimes. However, a closer analysis reveals differences in the impact different stakeholders have on the learning process. More concretely, local actors share knowledge more often and have a greater impact on stakeholders’ learning in democracies, while state actors display similar behavior across regimes in terms of learning and sharing knowledge. Thus, although there are notable similarities across regimes, multidirectional learning through stakeholder participation is influenced by the political context.

  19. Competition Regime

    Directory of Open Access Journals (Sweden)

    Danilo Icaza Ortiz

    2013-01-01

    Full Text Available This paper is a review of the competition regime works of various authors, published under the auspices of the University of the Hemispheres and the Corporation for Studies and Publications. Analyzes the structure, the general concepts, case law taken for development. Includes comments on the usefulness of this work for the study of competition law and the contribution to the lawyers who want to practice in this branch of economic law.

  20. Huygens-Fresnel principle: Analyzing consistency at the photon level

    Science.gov (United States)

    Santos, Elkin A.; Castro, Ferney; Torres, Rafael

    2018-04-01

    Typically the use of the Rayleigh-Sommerfeld diffraction formula as a photon propagator is widely accepted due to the abundant experimental evidence that suggests that it works. However, a direct link between the propagation of the electromagnetic field in classical optics and the propagation of photons where the square of the probability amplitude describes the transverse probability of the photon detection is still an issue to be clarified. We develop a mathematical formulation for the photon propagation using the formalism of electromagnetic field quantization and the path-integral method, whose main feature is its similarity with a fractional Fourier transform (FRFT). Here we show that because of the close relation existing between the FRFT and the Fresnel diffraction integral, this propagator can be written as a Fresnel diffraction, which brings forward a discussion of the fundamental character of it at the photon level compared to the Huygens-Fresnel principle. Finally, we carry out an experiment of photon counting by a rectangular slit supporting the result that the diffraction phenomenon in the Fresnel approximation behaves as the actual classical limit.

  1. Replica casting technique for micro Fresnel lenses characterization

    DEFF Research Database (Denmark)

    Gasparin, Stefania; Tosello, Guido; Hansen, Hans Nørgaard

    2012-01-01

    The available measuring techniques are not always suitable for the characterization of optical surfaces such as Fresnel lenses or polished specimens. A way to overcome these challenges is to reproduce the optical components surface using a polymer casting method and to measure the replicated...

  2. The temporal Fresnel number in terms of ray matrix elements

    International Nuclear Information System (INIS)

    Zhang Zhuhong; Fan Dianyuan

    1993-01-01

    By using the analogy between temporal ray matrix and the well known ray matrix, the temporal Fresnel number, which gives the qualitative and quasiquantitative characteristics (shape, width and chirp) of optical pulses, is derived. A concept of effective propagation time is introduced. Several typical examples are discussed. 6 refs

  3. Fresnel representation of the Wigner function: an operational approach.

    Science.gov (United States)

    Lougovski, P; Solano, E; Zhang, Z M; Walther, H; Mack, H; Schleich, W P

    2003-07-04

    We present an operational definition of the Wigner function. Our method relies on the Fresnel transform of measured Rabi oscillations and applies to motional states of trapped atoms as well as to field states in cavities. We illustrate this technique using data from recent experiments in ion traps [Phys. Rev. Lett. 76, 1796 (1996)

  4. Daylighting System Based on Novel Design of Linear Fresnel lens

    Directory of Open Access Journals (Sweden)

    Thanh Tuan Pham

    2017-10-01

    Full Text Available In this paper, we present a design and optical simulation of a daylighting system using a novel design of linear Fresnel lens, which is constructed based on the conservation of optical path length and edge ray theorem. The linear Fresnel lens can achieve a high uniformity by using a new idea of design in which each groove of the lens distributes sunlight uniformly over the receiver so that the whole lens also uniformly distributes sunlight over the receiver. In this daylighting system, the novel design of linear Fresnel lens significantly improves the uniformity of collector and distributor. Therefore, it can help to improve the performance of the daylighting system. The structure of the linear Fresnel lenses is designed by using Matlab. Then, the structure of lenses is appreciated by ray tracing in LightToolsTM to find out the optimum lens shape. In addition, the simulation is performed by using LightToolsTM to estimate the efficiency of the daylighting system. The results show that the designed collector can achieve the efficiency of ~80% with the tolerance of ~0.60 and the concentration ratio of 340 times, while the designed distributor can reach a high uniformity of >90%.

  5. High resolution Fresnel zone plate laser alignment system

    International Nuclear Information System (INIS)

    Bressler, V.E.; Fischer, G.E.; Ruland, R.E.; Wang, T.

    1992-03-01

    The existing Fresnel zone plate laser alignment system is currently being extended and upgraded for the Final Focus Test Beam (FFTB). Previously, the resolution of this system has been several tens of micrometers. After the upgrade, the resolution will be a few micrometers. Details of the upgrade as well as simulation and experimental results will be presented

  6. Improvements on Fresnel arrays for high contrast imaging

    Science.gov (United States)

    Wilhem, Roux; Laurent, Koechlin

    2018-03-01

    The Fresnel Diffractive Array Imager (FDAI) is based on a new optical concept for space telescopes, developed at Institut de Recherche en Astrophysique et Planétologie (IRAP), Toulouse, France. For the visible and near-infrared it has already proven its performances in resolution and dynamic range. We propose it now for astrophysical applications in the ultraviolet with apertures from 6 to 30 meters, aimed at imaging in UV faint astrophysical sources close to bright ones, as well as other applications requiring high dynamic range. Of course the project needs first a probatory mission at small aperture to validate the concept in space. In collaboration with institutes in Spain and Russia, we will propose to board a small prototype of Fresnel imager on the International Space Station (ISS), with a program combining technical tests and astrophysical targets. The spectral domain should contain the Lyman- α line ( λ = 121 nm). As part of its preparation, we improve the Fresnel array design for a better Point Spread Function in UV, presently on a small laboratory prototype working at 260 nm. Moreover, we plan to validate a new optical design and chromatic correction adapted to UV. In this article we present the results of numerical propagations showing the improvement in dynamic range obtained by combining and adapting three methods : central obturation, optimization of the bars mesh holding the Fresnel rings, and orthogonal apodization. We briefly present the proposed astrophysical program of a probatory mission with such UV optics.

  7. Up scaling and test results of an advanced Fresnel greenhouse

    NARCIS (Netherlands)

    Sonneveld, P.J.; Swinkels, G.L.A.M.; Tuijl, van B.A.J.; Janssen, H.J.J.; Zwart, de H.F.

    2012-01-01

    A greenhouse with Fresnel lenses in the south facing roof and a receiver for concentrated Photovoltaics with water cooling (CPVT system) will result in electrical and thermal energy output from the solar energy excess entering a greenhouse. The PV system converts about half of the direct radiation

  8. Lightweight Inexpensive Ozone Lidar Telescope Using a Plastic Fresnel Lens

    Science.gov (United States)

    DeYoung, Russell J.; Notari, Anthony; Carrion, William; Pliutau, Denis

    2014-01-01

    An inexpensive lightweight ozone lidar telescope was designed, constructed and operated during an ozone lidar field campaign. This report summarizes the design parameters and performance of the plastic Fresnel lens telescope and shows the ozone lidar performance compared to Zemax calculations.

  9. Semi-analytical fluid study of the laser wake field excitation in the strong intensity regime

    Energy Technology Data Exchange (ETDEWEB)

    Jovanović, D., E-mail: djovanov@ipb.ac.rs [Institute of Physics, University of Belgrade, Belgrade (Serbia); Fedele, R., E-mail: renato.fedele@na.infn.it [Dipartimento di Fisica, Universitá di Napoli Federico II, Napoli (Italy); INFN Sezione di Napoli, Napoli (Italy); Belić, M., E-mail: milivoj.belic@qatar.tamu.edu [Texas A & M University at Qatar, Doha (Qatar); De Nicola, S., E-mail: sergio.denicola@spin.cnr.it [Dipartimento di Fisica, Universitá di Napoli Federico II, Napoli (Italy); INFN Sezione di Napoli, Napoli (Italy); CNR-SPIN, Complesso Universitario di Monte S' Angelo, Napoli (Italy)

    2016-09-01

    We present an analytical and numerical study of the interaction of a multi-petawatt, pancake-shaped laser pulse with an unmagnetized plasma. The study has been performed in the ultrarelativistic regime of electron jitter velocities, in which the plasma electrons are almost completely expelled from the pulse region. The calculations are applied to a laser wake field acceleration scheme with specifications that may be available in the next generation of Ti:Sa lasers and with the use of recently developed pulse compression techniques. A set of novel nonlinear equations is derived using a three-timescale description, with an intermediate timescale associated with the nonlinear phase of the electromagnetic wave and with the spatial bending of its wave front. They describe, on an equal footing, both the strong and the moderate laser intensity regimes, pertinent to the core and to the edges of the pulse.

  10. Flow visualization study of post critical heat flux region for inverted bubbly, slug and annular flow regimes

    International Nuclear Information System (INIS)

    Denten, J.G.; Ishii, M.

    1988-11-01

    A visual study of film boiling using still photographic and high- speed motion picture methods was carried out in order to analyze the post-CHF hydrodynamics for steady-state inlet pre-CHF two-phase flow regimes. Pre-CHF two-phase flow regimes were established by introducing Freon 113 liquid and nitrogen gas into a jet core injection nozzle. An idealized, post-CHF two-phase core initial flow geometry (cylindrical multiphase jet core surrounded by a coaxial annulus of gas) was established at the nozzle exit by introducing nitrogen gas into the annular gap between the jet nozzle two-phase effluent and the heated test section inlet. For the present study three basic post-CHF flow regimes have been observed: the rough wavy regime (inverted annular flow preliminary break down), the agitated regime (transition between inverted annular and dispersed droplet flow), and the dispersed ligament/droplet regime. For pre-CHF bubbly flow in the jet nozzle, the post-CHF flow (beginning from jet nozzle exit/heated test section inlet) consists of the rough wavy regime, followed by the agitated and then the dispersed ligament/droplet regime. In the same way, for pre-CHF slug flow in the jet core, the post-CHF flow is comprised of the agitated regime at the nozzle exit, followed by the dispersed regime. Pre-CHF annular jet core flow results in a small, depleted post-CHF agitated flow regime at the nozzle exit, immediately followed by the dispersed ligament/droplet regime. Observed post dryout hydrodynamic behavior is reported, with particular attention given to the transition flow pattern between inverted annular and dispersed droplet flow. 43 refs., 20 figs., 5 tabs

  11. Helium transport and exhaust studies in enhanced confinement regimes in DIII-D

    International Nuclear Information System (INIS)

    Wade, M.R.; Hillis, D.L.; Hogan, J.T.; Mahdavi, M.A.; Maingi, R.; West, W.P.; Burrell, K.H.; Finkenthal, D.F.; Gohil, P.; Groebner, R.J.

    1995-02-01

    A better understanding of helium transport in the plasma core and edge in enhanced confinement regimes is now emerging from recent experimental studies on DIII-D. Overall, the results are encouraging. Significant helium exhaust (τ* He /τ E ∼ 11) has been obtained in a diverted, ELMing H-mode plasma simultaneous with a central source of helium. Detailed analysis of the helium profile evolution indicates that the exhaust rate is limited by the exhaust efficiency of the pump (∼5%) and not by the intrinsic helium transport properties of the plasma. Perturbative helium transport studies using gas puffing have shown that D He /X eff ∼1 in all confinement regimes studied to date (including H-mode and VH-mode). Furthermore, there is no evidence of preferential accumulation of helium in any of these regimes. However, measurements in the core and pumping plenum show a significant dilution of helium as it flows from the plasma core to the pumping plenum. Such dilution could be the limiting factor in the overall removal rate of helium in a reactor system

  12. Online recognition of the multiphase flow regime and study of slug flow in pipeline

    International Nuclear Information System (INIS)

    Guo Liejin; Bai Bofeng; Zhao Liang; Wang Xin; Gu Hanyang

    2009-01-01

    Multiphase flow is the phenomenon existing widely in nature, daily life, as well as petroleum and chemical engineering industrial fields. The interface structure among multiphase and their movement are complicated, which distribute random and heterogeneously in the spatial and temporal scales and have multivalue of the flow structure and state. Flow regime is defined as the macro feature about the multiphase interface structure and its distribution, which is an important feature to describe multiphase flow. The energy and mass transport mechanism differ much for each flow regimes. It is necessary to solve the flow regime recognition to get a clear understanding of the physical phenomena and their mechanism of multiphase flow. And the flow regime is one of the main factors affecting the online measurement accuracy of phase fraction, flow rate and other phase parameters. Therefore, it is of great scientific and technological importance to develop new principles and methods of multiphase flow regime online recognition, and of great industrial background. In this paper, the key reasons that the present method cannot be used to solve the industrial multiphase flow pattern recognition are clarified firstly. Then the prerequisite to realize the online recognition of multiphase flow regime is analyzed, and the recognition rules for partial flow pattern are obtained based on the massive experimental data. The standard templates for every flow regime feature are calculated with self-organization cluster algorithm. The multi-sensor data fusion method is proposed to realize the online recognition of multiphase flow regime with the pressure and differential pressure signals, which overcomes the severe influence of fluid flow velocity and the oil fraction on the recognition. The online recognition method is tested in the practice, which has less than 10 percent measurement error. The method takes advantages of high confidence, good fault tolerance and less requirement of single

  13. Study and optimization of operating regimes of NPP district heating system

    International Nuclear Information System (INIS)

    Bunin, V.S.; Vasil'ev, M.K.; Kudryavtsev, A.A.; Gorbashev, Yu.B.; Gadzhij, V.M.

    1980-01-01

    Thermal tests of the system with two reactors and four turbines have been carried out for the purpose of verification of operating regimes of the NPP district heating system with boiling single-curcuit RBMK-1000 reactors and K-500-65/3000 turbines. The system is designed for heat supply of habitable settlement and industrial site. The data processing have been carried out by the BESM-6 computer representing distributions of heat flow, steam, water and their parameters and determining the main energy indices of the system. Calculations of the system operating regime variables during the year have been carried out with the help of this program. It has been expected that the system provided heat consumption of 232 MW at calculated regime of thermal loading of the district, temperature regime of the system water of 130/170 deg C, relative load of hot water supply of 0.2 and duration of heating period of 4800 h. Calculations demonstrated that distric heat supply by NPP allowed one to supplant about 85 thous. of reference fuel/year of organic fuel. About 63 thous. of reference fuel/year are required for compensation of decrease of electric energy production in a condensation cycle. It has been also shown, that replacing the four-stroke system heaters by one-stroke heaters permits to drop system water underheating 1.5 times and, respectively, electric energy underproduction to 72 mln Mj (20 mln, kWxh). It produces additional economy of 6.6 thous. reference fuel/year. Calculations of its heat system have been conducted in order to determine the influence of water consumption in an intermediate circuit on the system efficiency. It has been shown that with the increase of water consumption energy power losses decrease. Thus, the above studied have demonstrated that the use of the single-circuit NPP district heating systems leads to considerable economy of fuel

  14. A RELAP5 study to identify flow regime in natural circulation phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Sabundjian, Gaiane; Torres, Walmir M.; Macedo, Luiz A.; Mesquita, Roberto N.; Andrade, Delvonei A.; Umbehaun, Pedro E.; Conti, Thadeu N.; Masotti, Paulo H.F.; Belchior Junior, Antonio; Angelo, Gabriel, E-mail: gdjian@ipen.b, E-mail: umbehaun@ipen.b, E-mail: wmtorres@ipen.b, E-mail: tnconti@ipen.b, E-mail: rnavarro@ipen.b, E-mail: lamacedo@ipen.b, E-mail: pmasotti@ipen.b, E-mail: abelchior@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    There has been a crescent interest in the scientific community in the study of natural circulation phenomenon. New generation of compact nuclear reactors uses the natural circulation of the fluid as a system of cooling and of residual heat removal in case of accident or shutdown. The objective of this paper is to compare the flow patterns of experimental data and numerical simulation for the natural circulation phenomenon in two-phase flow regime. An experimental circuit built with glass tubes is used for the experiments. Thus, it allows the thermal hydraulic phenomena visualization. There is an electric heater as the heat source, a heat exchanger as the heat sink and an expansion tank to accommodate fluid density excursions. The circuit instrumentation consists of thermocouples and pressure meters to better keep track of the flow and heat transfer phenomena. Data acquisition is performed through a computer interface developed with LABVIEW. The characteristic of the regime is identified using photography techniques. Numerical modeling and simulation is done with the thermal hydraulic code RELAP5, which is widely used for this purpose. This numerical simulation is capable to reproduce some of the flow regimes which are present in the circuit for the natural circulation phenomenon. Comparison between experimental and numerical simulation is presented in this work. (author)

  15. Determination of scattering center of multipath signals using geometric optics and Fresnel zone concepts

    Directory of Open Access Journals (Sweden)

    Kamil Yavuz Kapusuz

    2014-06-01

    Full Text Available In this study, a method for determining scattering center (or center of scattering points of a multipath is proposed, provided that the direction of arrival of the multipath is known by the receiver. The method is based on classical electromagnetic wave principles in order to determine scattering center over irregular terrain. Geometrical optics (GO along with Fresnel zone concept is employed, as the receiver, the transmitter positions and irregular terrain data are assumed to be provided. The proposed method could be used at UHF bands, especially, operations of radars and electronic warfare applications.

  16. Beam propagation modeling of modified volume Fresnel zone plates fabricated by femtosecond laser direct writing.

    Science.gov (United States)

    Srisungsitthisunti, Pornsak; Ersoy, Okan K; Xu, Xianfan

    2009-01-01

    Light diffraction by volume Fresnel zone plates (VFZPs) is simulated by the Hankel transform beam propagation method (Hankel BPM). The method utilizes circularly symmetric geometry and small step propagation to calculate the diffracted wave fields by VFZP layers. It is shown that fast and accurate diffraction results can be obtained with the Hankel BPM. The results show an excellent agreement with the scalar diffraction theory and the experimental results. The numerical method allows more comprehensive studies of the VFZP parameters to achieve higher diffraction efficiency.

  17. Advanced split-illumination electron holography without Fresnel fringes

    Energy Technology Data Exchange (ETDEWEB)

    Tanigaki, Toshiaki, E-mail: tanigaki-toshiaki@riken.jp [Center for Emergent Matter Science (CEMS), RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Aizawa, Shinji; Park, Hyun Soon [Center for Emergent Matter Science (CEMS), RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Matsuda, Tsuyoshi [Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan); Harada, Ken [Central Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama 350-0395 (Japan); Shindo, Daisuke [Center for Emergent Matter Science (CEMS), RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Sendai 980-8577 (Japan)

    2014-02-01

    Advanced split-illumination electron holography was developed by employing two biprisms in the illuminating system to split an electron wave into two coherent waves and two biprisms in the imaging system to overlap them. A focused image of an upper condenser-biprism filament was formed on the sample plane, and all other filaments were placed in its shadow. This developed system makes it possible to obtain precise reconstructed object waves without modulations due to Fresnel fringes, in addition to holograms of distant objects from reference waves. - Highlights: • Advanced split-illumination electron holography without Fresnel fringes is developed. • Two biprisms are installed in illuminating system of microscope. • High-precision holographic observations of an area locating far from the sample edge become possible.

  18. Advanced split-illumination electron holography without Fresnel fringes

    International Nuclear Information System (INIS)

    Tanigaki, Toshiaki; Aizawa, Shinji; Park, Hyun Soon; Matsuda, Tsuyoshi; Harada, Ken; Shindo, Daisuke

    2014-01-01

    Advanced split-illumination electron holography was developed by employing two biprisms in the illuminating system to split an electron wave into two coherent waves and two biprisms in the imaging system to overlap them. A focused image of an upper condenser-biprism filament was formed on the sample plane, and all other filaments were placed in its shadow. This developed system makes it possible to obtain precise reconstructed object waves without modulations due to Fresnel fringes, in addition to holograms of distant objects from reference waves. - Highlights: • Advanced split-illumination electron holography without Fresnel fringes is developed. • Two biprisms are installed in illuminating system of microscope. • High-precision holographic observations of an area locating far from the sample edge become possible

  19. Angular criterion for distinguishing between Fraunhofer and Fresnel diffraction

    International Nuclear Information System (INIS)

    Medina, Francisco F.; Garcia-Sucerquia, Jorge; Castaneda, Roman; Matteucci, Giorgio

    2003-03-01

    The distinction between Fresnel and Fraunhofer diffraction is a crucial condition for the accurate analysis of diffracting structures. In this paper we propose a criterion based on the angle subtended by the first zero of the diffraction pattern from the center of the diffracting aperture. The determination of the zero of the diffraction pattern is the crucial point for assuring the precision of the criterion. It mainly depends on the dynamical range of the detector. Therefore, the applicability of adequate thresholds for different detector types is discussed. The criterion is also generalized by expressing it in terms of the number of Fresnel zones delimited by the aperture. Simulations are reported for illustrating the feasibility of the criterion. (author)

  20. Performance testing of a Fresnel/Stirling micro solar energy conversion system

    International Nuclear Information System (INIS)

    Aksoy, Fatih; Karabulut, Halit

    2013-01-01

    Highlights: • Solar energy has a big importance among the renewable energy sources. • A micro solar energy system consisted of a Stirling engine and Fresnel lens was tested. • Solar radiation was directly focused into a cavity. • Cavities made of copper, aluminium and stainless steel were used. • The maximum performance was obtained with aluminium cavity. - Abstract: In this study, a beta-type Stirling engine was tested with concentrated solar radiation. The displacer cylinder of the engine was modified by integrating a concentrated solar radiation receiver. Basically, the receiver is a cavity drilled in a separate part mounted on top of the displacer cylinder by screws. Tests were conducted with three cavities made of aluminium, copper and stainless steel. The solar radiation was concentrated by a Fresnel lens with 1.4 m 2 capture area. Among the cavities, the highest performance was provided by aluminium cavity and followed by the stainless steel and copper cavities respectively. The maximum shaft power was observed as 64.4 W at systematic tests conducted with the aluminium cavity. The maximum shaft power corresponded to 218 rpm engine speed and 2.82 Nm torque. For this shaft power, the overall conversion efficiency of the system was estimated to be 5.64%. The maximum torque measured with aluminium cavity was 2.93 Nm corresponding to 177 rpm below which the engine stopped. The Fresnel-lens/Stirling-engine micro power plant established in this investigation was more efficient than the micro power plants presented in the literature

  1. High spatial resolution X-UV Fresnel zone plates imaging; Imagerie a haute resolution spatiale dans le domaine X-UV a l'aide de lentilles a zone de Fresnel

    Energy Technology Data Exchange (ETDEWEB)

    Pichet-Thomasset, M

    1999-07-01

    The goal of this work is to study the capabilities of imaging of Fresnel zone plates in the 1.5. and 2 keV X-ray range for the imaging of laser-produced plasmas. The diagnostic is composed of a Fresnel zone plate with good imaging capabilities and a multilayer mirror to select the spectral emission bandwidth of the plasma we want to study. This diagnostic was evaluated at the Centre d'Etudes de Limeil-Valenton experiments to study spatial resolution with this kind of X-ray source. The images we obtained showed that there is no geometric aberrations over an object field of several millimetre. Fresnen zone plates are often used for monochromatic biological objects imaging in the water window around 400 eV but they offer large prospects for laser produced plasma imaging. (author)

  2. Effect of Fresnel Reflectivity in a Spherical Turbid Medium

    CERN Document Server

    Elghazaly, A

    2003-01-01

    Radiative transfer problem for anisotropic scattering in a spherical homogeneous, turbid medium with angular dependent (specular) reflecting boundary is solved using the pomraning-Eddington approximation method. The angular dependent reflectivity of the boundary is considered as Fresnel's reflection probability function. The partial heat flux is calculated with anisotropic scattering through a homogeneous solid sphere. our results are compared with the available data and give an excellent agreement.

  3. Effect of Fresnel Reflectivity in a Spherical Turbid Medium

    International Nuclear Information System (INIS)

    Elghazaly, A.; Attia, M.T.

    2003-01-01

    Radiative transfer problem for anisotropic scattering in a spherical homogeneous, turbid medium with angular dependent (specular) reflecting boundary is solved using the pomraning-Eddington approximation method. The angular dependent reflectivity of the boundary is considered as Fresnel's reflection probability function. The partial heat flux is calculated with anisotropic scattering through a homogeneous solid sphere. our results are compared with the available data and give an excellent agreement

  4. Zeroes of functions of Fresnel complementary integral type

    Directory of Open Access Journals (Sweden)

    Mario Alberto Villalobos Arias

    2017-02-01

    Full Text Available Theoretical upper and lower bounds are established for zeroes of a parametric family of functions which are defined by integrals of the same type as  the Fresnel complementary integral. Asymptotic properties for these bounds are obtained as well as monotony properties of the localization  intervals.  Given the value of the parameter an analytical-numerical procedure is deduced to enclose all  zeros of a given function with an a priori error.

  5. Design and construction of a Fresnel linear distiller

    International Nuclear Information System (INIS)

    Saettone, E.

    2014-01-01

    It was designed a Fresnel linear distiller based on optical calculations obtained from taking into account Lima's latitude value, Earth inclination angle and heat absorber cavity's dimensions. The 5.6 m 2 reflective surface concentrator of the distiller was constructed with 32 plane rectangular mirrors; the heat absorber cavity was made with a rectangular blackened aluminum tube 1 m long and installed 2.5 m over the plane of mirrors. The Fresnel linear distiller was installed at the University of Lima and experimental tests were performed during no cloudy summer days. There were measured ambient temperature, heat absorber cavity temperature, radiant flux and fresh water volume. From this, it was obtained a production of 0.89 liters/hour and 0.79 L/m 2 , and it was calculated a total performance of 34.5% in desalting sea water. Finally, it is presented a comparison between Fresnel linear distiller (FLD) and parabolic trough distiller (PTD) with similar dimensions and characteristics. It is obtained that the last one produced almost 32% more fresh water than the former, but at the same time, the FLD is almost 20% cheaper than PTD. However, water cost production with both distillers using is almost the same. (author)

  6. Cylindrically symmetric Fresnel lens for high concentration photovoltaic

    Science.gov (United States)

    Hung, Yu-Ting; Su, Guo-Dung

    2009-08-01

    High concentration photovoltaic (HCPV) utilizes point-focus cost-effective plastic Fresnel lens. And a millimeter-sized Ill-V compound multi-junction solar cell is placed underneath focusing optics which can achieve cell efficiency potential of up to 40.7 %. The advantage of HCPV makes less solar cell area and higher efficiency; however, the acceptance angle of HCPV is about +/-1°, which is very small and the mechanical tracking of the sun is necessary. In order to reduce the power consumption and the angle tracking error of tracking systems, a light collector model with larger acceptance angle is designed with ZEMAX®. In this model, the original radially symmetric Fresnel lens of HCPV is replaced by cylindrically symmetric Fresnel lens and a parabolic reflective surface. Light is collected in two dimensions separately. And a couple of lenses and a light pipe are added before the solar cell chip in order to collect more light when sun light deviates from incident angle of 00. An acceptance angle of +/-10° is achieved with GCR 400.

  7. Photometric analysis on concentration characteristics of Fresnel lenses; Fotometoriho wo mochiita Fresnel lens no shuko tokusei kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, A [Tokyo University of Agriculture and Technology, Tokyo (Japan)

    1997-11-25

    Light concentration characteristics of Fresnel lenses were analyzed by using photometry. Light concentrating systems include a reflective system represented by a rotary parabolic mirror, and a refractive system represented by the Fresnel lens. The refractive system has a focused section broadened as much as the dispersion effect in association with refraction, and cannot derive a focus with high magnification as compared with the reflective system which can achieve it. The refractive system causes reduction in collected light intensity to about half on a parax, hence a large amount of loss. However, the system can be made available inexpensively due to mass production by using mold formation. Although it is difficult to utilize all of the light, 95% of the received radiation is concentrated in an opening area with a radius of about 4G (G is a radius of an image of solar light at a focus plane which passes through the center of a Fresnel lens). The average magnification of light concentration at this time in the opening area reaches 390 times. When a 3-D compound parabolic concentrator (CPC) with a radius of 4G is placed on a lens focus as a secondary light concentrator, the final magnification of light concentration shows a value of about 2700 times, whereas restoration of 39% is possible, as compared with a rotary parabolic mirror. The system has sufficient possibility to be used for high-temperature light concentration. 3 refs., 5 figs., 1 tab.

  8. Parametric studies of contrail ice particle formation in jet regime using microphysical parcel modeling

    Directory of Open Access Journals (Sweden)

    H.-W. Wong

    2010-04-01

    Full Text Available Condensation trails (contrails formed from water vapor emissions behind aircraft engines are the most uncertain components of the aviation impacts on climate change. To gain improved knowledge of contrail and contrail-induced cirrus cloud formation, understanding of contrail ice particle formation immediately after aircraft engines is needed. Despite many efforts spent in modeling the microphysics of ice crystal formation in jet regime (with a plume age <5 s, systematic understanding of parametric effects of variables affecting contrail ice particle formation is still limited. In this work, we apply a microphysical parcel modeling approach to study contrail ice particle formation in near-field aircraft plumes up to 1000 m downstream of an aircraft engine in the soot-rich regime (soot number emission index >1×1015 (kg-fuel−1 at cruise. The effects of dilution history, ion-mediated nucleation, ambient relative humidity, fuel sulfur contents, and initial soot emissions were investigated. Our simulation results suggest that ice particles are mainly formed by water condensation on emitted soot particles. The growth of ice coated soot particles is driven by water vapor emissions in the first 1000 m and by ambient relative humidity afterwards. The presence of chemi-ions does not significantly contribute to the formation of ice particles in the soot-rich regime, and the effect of fuel sulfur contents is small over the range typical of standard jet fuels. The initial properties of soot emissions play the most critical role, and our calculations suggest that higher number concentration and smaller size of contrail particle nuclei may be able to effectively suppress the formation of contrail ice particles. Further modeling and experimental studies are needed to verify if our findings can provide a possible approach for contrail mitigation.

  9. Experimental Investigation of the Fresnel Drag Effect in RF Coaxial Cables

    Directory of Open Access Journals (Sweden)

    Brotherton D.

    2011-01-01

    Full Text Available An experiment that confirms the Fresnel drag formalism in RF coaxial cables is reported. The Fresnel "drag" in bulk dielectrics and in optical fibers has previously been well established. An explanation for this formalism is given, and it is shown that there is no actual drag phenomenon, rather that the Fresnel drag effect is merely the consequence of a simplified description of EM scattering within a dielectric in motion wrt the dynamical 3-space. The Fresnel drag effect plays a critical role in the design of various light-speed anisotropy detectors.

  10. Experimental Investigation of the Fresnel Drag Effect in RF Coaxial Cables

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2011-01-01

    Full Text Available An experiment that confirms the Fresnel drag formalism in RF coaxial cables is re- ported. The Fresnel ‘drag’ in bulk dielectrics and in optical fibers has previously been well established. An explanation for this formalism is given, and it is shown that there is no actual drag phenomenon, rather that the Fresnel drag effect is merely the conse- quence of a simplified description of EM scattering within a dielectric in motion wrt the dynamical 3-space. The Fresnel drag effect plays a critical role in the design of various light-speed anisotropy detectors.

  11. Emergence of Fresnel diffraction zones in gravitational lensing by a cosmic string

    Energy Technology Data Exchange (ETDEWEB)

    Fernández-Núñez, Isabel [Departament de Física Quàntica i Astrofísica, Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain); Institut de Ciències del Cosmos (ICCUB), Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain); Bulashenko, Oleg, E-mail: oleg.bulashenko@ub.edu [Departament de Física Quàntica i Astrofísica, Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain)

    2017-06-09

    The possibility to detect cosmic strings – topological defects of early Universe, by means of wave effects in gravitational lensing is discussed. To find the optimal observation conditions, we define the hyperbolic-shaped Fresnel observation zones associated with the diffraction maxima and analyse the frequency patterns of wave amplification corresponding to different alignments. In particular, we show that diffraction of gravitational waves by the string may lead to significant amplification at cosmological distances. The wave properties we found are quite different from what one would expect, for instance, from light scattered off a thin wire or slit, since a cosmic string, as a topological defect, gives no shadow at all. - Highlights: • Interference and diffraction of gravitational waves by a cosmic string are studied. • Uniform asymptotic theory of diffraction is applied for a finite distance source. • Hyperbolic-shaped Fresnel observation zones associated with maxima of diffraction. • Frequency patterns modulated by diffraction for different string alignments are given. • The method is applicable to condensed-matter defects and other types of waves.

  12. Development of a Fresnel lens for cold neutrons based on neutron refractive optics

    CERN Document Server

    Oku, T; Moriyasu, S; Yamagata, Y; Ohmori, H; Takizawa, Y; Shimizu, H M; Hirota, T; Kiyanagi, Y; Ino, T; Furusaka, M; Suzuki, J

    2001-01-01

    We have developed compound refractive lenses (CRLs) for cold neutrons, which are made of vitreous silica and have an effective potential of (90.1-2.7x10 sup - sup 4 i) neV. In the case of compound refractive optics, neutron absorption by the material deteriorates lens performance. Thus, to prevent an increase in neutron absorption with increasing beam size, we have developed Fresnel lenses using the electrolytic in-process dressing grinding technique. The lens characteristics were carefully investigated with experimental and numerical simulation studies. The lenses functioned as a neutron focusing lens, and the focal length of 14 m was obtained with a 44-element series of the Fresnel lenses for 10 A neutrons. Moreover, good neutron transmission of 0.65 for 15 A neutrons was obtained due to the shape effect. According to comprehensive analysis of the obtained results, it is possible to realize a CRL for practical use by choosing a suitable lens shape and material.

  13. Multiple reflections and Fresnel absorption in an actual 3D keyhole during deep penetration laser welding

    Energy Technology Data Exchange (ETDEWEB)

    Jin Xiangzhong [Laser Institute of Hunan University, Changsha, Hunan, 410082 (China); Berger, Peter [Institut fuer Strahlwerkzeuge (IFSW), University of Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart (Germany); Graf, Thomas [Institut fuer Strahlwerkzeuge (IFSW), University of Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart (Germany)

    2006-11-07

    In laser welding experiments of glass, keyhole shapes are observed by two high-speed cameras from two perpendicular directions. From the obtained keyhole pictures, it can be seen that in medium- and low-speed laser penetration welding, the main distortion of the keyhole is not the section metamorphosis from rotational symmetry, but the bending of its centre line. Based on such a keyhole photograph, the keyhole profiles and its centre line are determined by the method of polynomial fitting. Then, under the assumption of a circular cross section at each depth of the keyhole, the behaviour of the laser beam in the keyhole is analysed by tracing a ray of light using geometrical optics theory; the Fresnel absorption and multiple reflections in the keyhole are systematically studied, and the laser intensities absorbed on the keyhole walls are calculated. The absorbed laser intensity is not distributed uniformly on the keyhole wall. The keyhole wall absorbs laser intensity mainly on the half-part of the keyhole wall near the front wall. Because of the high absorptivity of the glass, Fresnel absorption from the first incidence of a laser beam plays a dominant role in the final laser intensity distribution on the keyhole wall, multiple reflections have some minor effects on the intensity distribution on the bottom part of the keyhole.

  14. study of solid-liquid flow regimes in mining industry using gamma radiation

    International Nuclear Information System (INIS)

    Salgado, Cesar M.; Brandao, Luis E.B.; Nunes, Rogerio C.; Nascimento, Ana C. de H.; Salgado, William L.

    2013-01-01

    One of the most promising areas in the mining industry is the development of devices for measuring solid mass flowrate in pipelines, mainly in transportation of ore. These units are composed of interconnected pipes where transport of the material is accomplished by pumps capable of driving the ore pellets using water. One of the problems inherent in these systems is the stratification if a critical velocity is reached, the ore pellets begin to sediment at the bottom of the pipe and it may block the system. The solid phase displacement behavior depends on a number of factors (water flowrate, density, pipe diameter, average size of the pellet) which makes the flow regime knowledge essential to the appropriate operation of the system. An apparatus to evaluate the stratification level through of particle (ore pellets) spatial distributions inside the pipe is important because it increases the safety condition of pumping and transportation of solid phase. Therefore, this work presents a study to optimize the geometrical parameters for the identification of a possible stratification of the solid phase inside a pipeline. The detection system uses different NaI(Tl) detectors and gamma ray sources (fan beam geometry), adequately positioned in order to calculate transmitted and scattered beams. Additionally, theoretical models for different flow regimes (homogeneous and stratified) have been developed using MCNP-X mathematical code. (author)

  15. Summary Authoritarialism as Political Regime: Analysis of Historical and Empirical Studies

    Directory of Open Access Journals (Sweden)

    O. D. Grossman

    2016-01-01

    Full Text Available This article is devoted to the problems of existence of authoritarian regimes. The ambiguity of the resulting data determines the importance of the considered research. Authoritarianism is quite complicated socio-political phenomenon. For this reason, there are a lot of typologies and special features of authoritarianism as a political regime. Authoritarianism is not only a political regime, but it is also a set of social and political characteristics. Some countries, where the authoritarian tendencies dominate, are economically developed, and they have a competitive economy, but other countries, which are steeped in a reactionary authoritarian, do not develop properly. From the materials of this article it should be concluded that the political regime in Russia is principally authoritarian, or to be specific it is liberal authoritarian regime. This political regime has been established for the whole history of our country, and it is supported by paternalistic political culture and special mindset our nation.

  16. Highly radiative plasmas for local transport studies and power and particle handling in reactor regimes

    International Nuclear Information System (INIS)

    Hill, K.W.; Bell, M.G.; Budny, R.

    1999-01-01

    To study the applicability of artificially enhanced impurity radiation for mitigation of the plasma-limiter interaction in reactor regimes, krypton and xenon gases were injected into TFTR supershots and high-l i plasmas. At neutral beam injection (NBI) powers P B ≥ 30 MW, carbon influxes (blooms) were suppressed, leading to improved energy confinement and neutron production in both D and DT plasmas, and the highest DT fusion energy production (7.6 MJ) in a TFTR pulse. Comparisons of the measured radiated power profiles with predictions of the MIST impurity transport code have guided studies of highly-radiative plasmas in ITER. The response of the electron and ion temperatures to greatly increased radiative losses from the electrons was used to study thermal transport mechanisms. (author)

  17. Highly radiative plasmas for local transport studies and power and particle handling in reactor regimes

    International Nuclear Information System (INIS)

    Hill, K.W.; Bell, M.G.; Budny, R.

    2001-01-01

    To study the applicability of artificially enhanced impurity radiation for mitigation of the plasma-limiter interaction in reactor regimes, krypton and xenon gases were injected into TFTR supershots and high-l i plasmas. At neutral beam injection (NBI) powers P B ≤30MW, carbon influxes (blooms) were suppressed, leading to improved energy confinement and neutron production in both D and DT plasmas, and the highest DT fusion energy production (7.6 MJ) in a TFTR pulse. Comparisons of the measured radiated power profiles with predictions of the MIST impurity transport code have guided studies of highly-radiative plasmas in ITER. The response of the electron and ion temperatures to greatly increased radiative losses from the electrons was used to study thermal transport mechanisms. (author)

  18. Highly Radiative Plasmas for Local Transport Studies and Power and Particle Handling in Reactor Regimes

    International Nuclear Information System (INIS)

    Bell, M.G.; Bell, R.E.; Budny, R.; Bush, C.E.; Hill, K.W.

    1998-01-01

    To study the applicability of artificially enhanced impurity radiation for mitigation of the plasma-limiter interaction in reactor regimes, krypton and xenon gases were injected into the Tokamak Fusion Test Reactor (TFTR) supershots and high-l(subscript) plasmas. At neutral beam injection (NBI) powers P(subscript B) greater than or equal to 30 MW, carbon influxes (blooms) were suppressed, leading to improved energy confinement and neutron production in both deuterium (D) and deuterium-tritium (DT) plasmas, and the highest DT fusion energy production (7.6 MJ) in a TFTR pulse. Comparisons of the measured radiated power profiles with predictions of the MIST impurity transport code have guided studies of highly-radiative plasmas in the International Thermonuclear Experimental Reactor (ITER). The response of the electron and ion temperatures to greatly increased radiative losses from the electrons was used to study thermal transport mechanisms

  19. Flow regimes

    International Nuclear Information System (INIS)

    Kh'yuitt, G.

    1980-01-01

    An introduction into the problem of two-phase flows is presented. Flow regimes arizing in two-phase flows are described, and classification of these regimes is given. Structures of vertical and horizontal two-phase flows and a method of their identification using regime maps are considered. The limits of this method application are discussed. The flooding phenomena and phenomena of direction change (flow reversal) of the flow and interrelation of these phenomena as well as transitions from slug regime to churn one and from churn one to annular one in vertical flows are described. Problems of phase transitions and equilibrium are discussed. Flow regimes in tubes where evaporating liquid is running, are described [ru

  20. Nonimaging achromatic shaped Fresnel lenses for ultrahigh solar concentration.

    Science.gov (United States)

    Languy, Fabian; Habraken, Serge

    2013-05-15

    The maximum concentration ratio achievable with a solar concentrator made of a single refractive primary optics is much more limited by the chromatic aberration than by any other aberration. Therefore achromatic doublets made with poly(methyl methacrylate) and polycarbonate are of great interest to enhance the concentration ratio and to achieve a spectrally uniform flux on the receiver. In this Letter, shaped achromatic Fresnel lenses are investigated. One lossless design is of high interest since it provides spectrally and spatially uniform flux without being affected by soiling problems. With this design an optical concentration ratio of about 8500× can be achieved.

  1. Accounting for Antenna in Half-Space Fresnel Coefficient Estimation

    Directory of Open Access Journals (Sweden)

    A. D'Alterio

    2012-01-01

    Full Text Available The problem of retrieving the Fresnel reflection coefficients of a half-space medium starting from measurements collected under a reflection mode multistatic configuration is dealt with. According to our previous results, reflection coefficient estimation is cast as the inversion of linear operator. However, here, we take a step ahead towards more realistic scenarios as the role of antennas (both transmitting and receiving is embodied in the estimation procedure. Numerical results are presented to show the effectiveness of the method for different types of half-space media.

  2. Rainbow and Fresnel diffraction effects in the heavy ion scattering

    International Nuclear Information System (INIS)

    Salvadori, M.C.B.S.

    1984-01-01

    A detailed theoretical analysis of the heavy-ion elastic scattering differential cross section, using the uniform semiclassical approximation of Berry in the sharp cut-off limit is presented. A decomposition of the cross section into four physically well-defined components is used in the analysis. The aim of the analysis is to explore the possibility of distinguishing at the cross-section level, between a pure raibow or Fresnel diffraction nature of the heavy-ion elastic scattering at above-barrier energies and not too large angles. (Author) [pt

  3. Thermoluminescence study of the trapped charge at an alumina surface electrode in different dielectric barrier discharge regimes

    Energy Technology Data Exchange (ETDEWEB)

    Ambrico, P F; Ambrico, M; Dilecce, G; De Benedictis, S [Consiglio Nazionale delle Ricerche, Istituto di Metodologie Inorganiche e dei Plasmi UOS Bari-c/o Dipartimento di Chimica, Universita degli Studi di Bari ' Aldo Moro' , via Orabona, 4, 70126 Bari (Italy); Colaianni, A [Dipartimento di Geologia e Geofisica, Universita degli Studi di Bari ' Aldo Moro' , via Orabona, 4, 70126 Bari (Italy); Schiavulli, L, E-mail: paolofrancesco.ambrico@cnr.i [Dipartimento Interateneo di Fisica, Universita degli Studi di Bari ' Aldo Moro' , via Orabona, 4, 70126 Bari (Italy)

    2010-08-18

    In this study, the charge trapping effect in alumina dielectric surfaces has been deeply investigated by means of a dedicated dielectric barrier discharge apparatus in different discharge regimes and gas mixtures. This work further validates our previous findings in the case of air discharges in a filamentary regime. Long lasting charge trapping has been evidenced by ex situ thermoluminescence characterizations of alumina dielectric barrier plates exposed to a plasma. The density of trapped surface charges was found to be higher in the glow discharge with respect to pseudo-glow and filamentary regimes, and for all regimes the minimum trap activation temperature was 390 K and the trap energy was less than or around 1 eV. This implies that in the case of glow discharges a higher reservoir of electrons is present. Also, the effect was found to persist for several days after running the discharge.

  4. Thermoluminescence study of the trapped charge at an alumina surface electrode in different dielectric barrier discharge regimes

    International Nuclear Information System (INIS)

    Ambrico, P F; Ambrico, M; Dilecce, G; De Benedictis, S; Colaianni, A; Schiavulli, L

    2010-01-01

    In this study, the charge trapping effect in alumina dielectric surfaces has been deeply investigated by means of a dedicated dielectric barrier discharge apparatus in different discharge regimes and gas mixtures. This work further validates our previous findings in the case of air discharges in a filamentary regime. Long lasting charge trapping has been evidenced by ex situ thermoluminescence characterizations of alumina dielectric barrier plates exposed to a plasma. The density of trapped surface charges was found to be higher in the glow discharge with respect to pseudo-glow and filamentary regimes, and for all regimes the minimum trap activation temperature was 390 K and the trap energy was less than or around 1 eV. This implies that in the case of glow discharges a higher reservoir of electrons is present. Also, the effect was found to persist for several days after running the discharge.

  5. Weyl Ordering Operator Formula Derived by IWOP Technique and Its Application for Fresnel Operator

    International Nuclear Information System (INIS)

    Fan Hongyi; Hu Liyun

    2009-01-01

    Based on the technique of integration within an ordered product of operators, the Weyl ordering operator formula is derived and the Fresnel operators' Weyl ordering is also obtained, which together with the Weyl transformation can immediately lead to Fresnel transformation kernel in classical optics. (general)

  6. Optimum design of nonimaging Fresnel lens; Hiketsuzo fureneru renzu no saiteki sekkei

    Energy Technology Data Exchange (ETDEWEB)

    Leutz, R.; Komai, K.; Akisawa, A.; Kashiwagi, T. [Tokyo University of Agriculture and Technology, Tokyo (Japan); Suzuki, A. [Unesco, Paris (France). Associations in Japan

    1999-11-25

    An optimum convex shaped nonimaging Fresnel lens is designed following the edge ray principle. The lens is evaluated by tracing rays and calculating a projective optical concentration ratio. This Fresnel lens can used as concentrator in photovoltaic and solar thermal applications. (author)

  7. Inward Processing Regime Promotion System in Vegetable Oil Industry: A Case Study of Turkey

    Directory of Open Access Journals (Sweden)

    Sinan Duru

    2017-04-01

    Full Text Available This study was conducted to determine applicability of the Inward Processing Regime (IPR in enterprises which are vegetable oil producers and exporters. The data was obtained from 26 vegetable oil producer and exporter enterprises by using survey method. Frequency tables, indices, and percentage calculating were used to analyse Data. Also, SWOT analysis was used to determine the strengths, weaknesses, opportunities and threats in the sector, and relationship among some variables were examined with correlation coefficient. According to research findings, 25 of the enterprises (96% utilised the IPR. Since the enterprises started to use that system; availability of cheap raw material, rate of capacity utilisation, market share, and export value all have increased. In addition, raw material was found as an important expense item, and the most important problems were qualified as raw material inadequacy and high input prices.

  8. Theoretical studying the stability of steady-state regime of a channel with a coolant condensation

    International Nuclear Information System (INIS)

    Savikhin, O.G.

    1987-01-01

    Based on the boiling channel stability theory, the channel steady-state stability with the coolant condensation is studied. Condensable coolants are used in the NPP steam-separator superheaters as well as in cryogenic technique. Under certain conditions the coolant flow rate and temperature fluctuations may be excited in the parallel channel system with coolant condensation, which produce a sufficient effect on the heat exchange equipment operation reliability. To describe unsteady processes of heat and mass transfer in the channel, a homogeneous two-phase flow one dimensional model is used. The results obtained allow one to make a conclusion concerning the effect of some parameters on condensing channel steady-state regime stability: reduction of inlet and outlet unheated communication length, pressure drop increase at the outlet plate and its reduction at the inlet one lead to the increase of stability margin

  9. Flow regimes

    International Nuclear Information System (INIS)

    Liles, D.R.

    1982-01-01

    Internal boundaries in multiphase flow greatly complicate fluid-dynamic and heat-transfer descriptions. Different flow regimes or topological configurations can have radically dissimilar interfacial and wall mass, momentum, and energy exchanges. To model the flow dynamics properly requires estimates of these rates. In this paper the common flow regimes for gas-liquid systems are defined and the techniques used to estimate the extent of a particular regime are described. Also, the current computer-code procedures are delineated and introduce a potentially better method is introduced

  10. The Fresnel Zone Light Field Spectral Imager

    Science.gov (United States)

    2017-03-23

    detection efficiency for weak signals . Additionally, further study should be done on spectral calibration methods for a FZLFSI. When dealing with weak ... detection assembly. The different image formation planes for each wavelength are constructed synthetically through processing the collected light ...a single micro-lens image. This character- istic also holds for wavelengths other than the design wavelength. 36 modified light field PSF is detected

  11. Synchrotron radiation focusing by a Bragg--Fresnel lens

    International Nuclear Information System (INIS)

    Aristov, V.V.; Basov, Y.A.; Snigirev, A.A.

    1989-01-01

    Since the discovery of x rays and until the present time the possibilities of their controlling and focusing have been widely discussed. In the hard spectrum region (λ∼1 A) the main focusing schemes are the following: geometrical focusing based on incoherent interaction of wave packets reflected by different regions of bending crystals and coherent (dynamic) focusing performed at the cost of the effect of refraction index angular dispersion near the exact Bragg angle value -θ B . A main disadvantage of geometrical focusing is low spatial resolution (∼0.1 mm) and temperature stability. In the case of coherent focusing a main disadvantage is a narrow angular aperture (∼10 sec. of arc) at spatial resolution (∼1--10 μm). Recently, advances in the development of diffraction physics and microstructuring technology open up possibilities for fabricating effective focusing x-ray optical elements---Bragg--Fresnel lenses (BFL)---with high spatial resolution (∼0.1 μm) at a wide angular aperture and high temperature stability. The present paper describes the main principles of Bragg--Fresnel optics (BFO). It presents the results on the synchrotron experiment and on observation of focusing. In this work the peculiarities of BFL diffraction contrast formation are investigated and image transmission using a BFL is performed. Possibilities of developing x-ray optical schemes of ultrahigh resolution on the basis of BFL elements are also discussed

  12. Experimental characterization of Fresnel-Köhler concentrators

    Science.gov (United States)

    Zamora, Pablo; Benítez, Pablo; Mohedano, Rubén; Cvetković, Aleksandra; Vilaplana, Juan; Li, Yang; Hernández, Maikel; Chaves, Julio; Miñano, Juan C.

    2012-01-01

    Most cost-effective concentrated photovoltaics (CPV) systems are based on an optical train comprising two stages, the first being a Fresnel lens. Among them, the Fresnel-Köhler (FK) concentrator stands out owing to both performance and practical reasons. We describe the experimental measurements procedure for FK concentrator modules. This procedure includes three main types of measurements: electrical efficiency, acceptance angle, and irradiance uniformity at the solar cell plane. We have collected here the performance features of two different FK prototypes (ranging different f-numbers, concentration ratios, and cell sizes). The electrical efficiencies measured in both prototypes are high and fit well with the models, achieving values up to 32.7% (temperature corrected, and with no antireflective coating on SOE or POE surfaces) in the best case. The measured angular transmission curves show large acceptance angles, again perfectly matching the expected values [measured concentration acceptance product (CAP) values over 0.56]. The irradiance pattern on the cell (obtained with a digital camera) shows an almost perfectly uniform distribution, as predicted by raytrace simulations. All these excellent on-sun results confirm the FK concentrator as a potentially cost-effective solution for the CPV market.

  13. Fluorescent sensing with Fresnel microlenses for optofluidic systems

    Science.gov (United States)

    Siudzińska, Anna; Miszczuk, Andrzej; Marczak, Jacek; Komorowska, Katarzyna

    2017-05-01

    The concept of fluorescent sensing in a microchannel equipped with focusing light Fresnel lenses has been demonstrated. The concept employs a line or array of Fresnel lenses generating a line or array of focused light spots within a microfluidic channel, to increase the sensitivity of fluorescent signal detection in the system. We have presented efficient methods of master mold fabrication based on the lithography method and focused ion beam milling. The flexible microchannel was fabricated by an imprint process with new thiolene-epoxy resin with a good ability to replicate even submicron-size features. For final imprinted lenses, the measured background to peak signal level shows more than nine times the increase in brightness at the center of the focal spot for the green part of the spectrum (532 nm). The effectiveness of the microlenses in fluorescent-marked Escherichia coli bacteria was confirmed in a basic fluoroscope experiment, showing the increase of the sensitivity of the detection by the order of magnitude.

  14. A study of Two-Phase Flow Regime Maps in Vertical and Horizontal Pipes

    International Nuclear Information System (INIS)

    Kim, Kyung Doo; Kang, Doo Hyuk

    2007-10-01

    A safety analysis code to design a pressurized water reactor and to obtain the licences including entire proprietary rights is under development in domestic research and development project. The purpose and scope of this report is to develop the flow regimes related models for inter-phase friction, wall frictions, wall heat transfer, and inter-phase heat and mass transfer in two-phase three-field equations. In order to choose choose the flow regime criteria, we have investigated various exiting best-estimate T/H codes in this chapter 2. They are the RELAP5-3D, TRAC-M, CATHARE, MARS codes. Around 500 references used in these codes have been collected and reviewed. Also we have investigated eleven papers in detail. In chapter 3, based on the selected flow regimes, the flow regime maps for a gas-liquid flow in horizontal and vertical tubes have decided including the mechanisms of flow regime transition regions. Conclusively, the process will be presented for choosing the best flow regime maps which occur in gas-liquid two-phase flow in horizontal and vertical pipes. We will look forward to decide the constitutive relations based upon the flow regime maps that are determined in this works. The constitutive relations will be used for the code under development

  15. Studies of multi-wavelength laser-induced damage on KDP crystals in the nanosecond regime

    International Nuclear Information System (INIS)

    Reyne, Stephane

    2011-01-01

    This thesis interests in the laser-induced damage mechanisms of KDP and DKDP crystals in the nanosecond regime. KDP is a non-linear material particularly used in the frequency converters of the Laser MegaJoule, which is under construction at the CEA-Cesta in France. For this facility, the KDP laser damage resistance is one of the keystones and is still under investigations to fix this problem. This is why this manuscript presents different studies which highlight the two main aspects of the nanosecond laser-induced damage of KDP frequency converters: the precursor defects and the mechanisms to initiate damage. First, we propose a study based on the analysis of several photos obtained by DIC microscopy of damage initiated by different wavelengths. A comparison with a code coupling the energy deposition and hydrodynamic is also done. Then, we interest in the influence of the defects geometry through a study based on the laser polarization effect on the laser damage resistance. By the comparison with a CEA home-made code, this study particularly underlines the possibility to define a new geometry for the precursor defects. This geometry proposed has the shape of an ellipsoid and is supposed to keep the crystal structure properties. Finally, we enlarge on the physical mechanisms initiating laser damage with pump-pump experiments. These tests consist in combining two radiations of different wavelengths which impacting the crystal simultaneously or are delayed one by the other. We then observe the influence of this wavelengths mixing on the KDP laser damage resistance. In particular, a coupling effect between the wavelengths of the mixture may occur as a function of the fluences combination. Finally, the goal of these specific studies is to accumulate new data in order to improve the understanding in the initiation of the laser damage in KDP and DKDP crystals in the nanosecond regime. In the end, these data will allow us to develop predictive models to simulate the laser

  16. Performance model and thermal comparison of different alternatives for the Fresnel single-tube receiver

    International Nuclear Information System (INIS)

    Montes, María J.; Barbero, Rubén; Abbas, Rubén; Rovira, Antonio

    2016-01-01

    Highlights: • A thermal model for a single-tube Fresnel receiver has been developed. • A comparative analysis based on different design parameters, has been carried out. • A comparative analysis based on different working fluids, has been carried out. • The receiver thermal performance is characterized by energy and exergy efficiencies. - Abstract: Although most of recent commercial Solar Thermal Power Plants (STPP) installed worldwide are parabolic trough plants, it seems that Linear Fresnel Collectors (LFC) are becoming an attractive option to generate electricity from solar radiation. Contrary to parabolic trough collectors, the design of LFC receivers has many degrees of freedom, and two basic designs can be found in the literature: single-tube and multi-tube design. This article studies the single-tube design, for which a thermal model has been developed. This model has been thought to be accurate enough to characterize the heat transfer in a non-elementary geometry and flexible enough to support changes of the characteristic parameters in the receiver design. The thermal model proposed is based on a two-dimensional, steady-state energy balance, in the receiver cross section and along its length. One of the features of the model is the characterization of the convective and radiative heat transfer in the receiver cavity, as it is not an elementary geometry. Another feature is the possibility of studying the receiver performance with different working fluids, both single-phase or two-phase. At last, the receiver performance has been characterized by means of the energy and exergy efficiency. Both variables are important for a complete receiver thermal analysis, as will be shown in the paper. The model has been first applied to the comparative study of the thermal performance of LFC receivers based on the value of some parameters: selective coating emissivity in the tube and inlet fluid thermal properties, for the case of using water/steam. As a second

  17. Steady-state thermal analysis of an innovative receiver for linear Fresnel reflectors

    International Nuclear Information System (INIS)

    Abbas, R.; Muñoz, J.; Martínez-Val, J.M.

    2012-01-01

    Highlights: ► An innovative multitube receiver for linear Fresnel reflectors is presented. ► Higher performance is achieved thanks to better heat transfer conditions. ► A wide range of designs that maximize efficiency for different conditions is found. ► Heat transfer fluid inlet temperature must be lower for low radiation intensities. ► Fresnel performance may be close to trough collectors, with lower costs. -- Abstract: The study of the performance of an innovative receiver for linear Fresnel reflectors is carried out in this paper, and the results are analyzed with a physics perspective of the process. The receiver consists of a bundle of tubes parallel to the mirror arrays, resulting on a smaller cross section for the same receiver width as the number of tubes increases, due to the diminution of their diameter. This implies higher heat carrier fluid speeds, and thus, a more effective heat transfer process, although it conveys higher pumping power as well. Mass flow is optimized for different tubes diameters, different impinging radiation intensities and different fluid inlet temperatures. It is found that the best receiver design, namely the tubes diameter that maximizes the exergetic efficiency for given working conditions, is similar for the cases studied. There is a range of tubes diameters that imply similar efficiencies, which can drive to capital cost reduction thanks to the flexibility of design. In addition, the length of the receiver is also optimized, and it is observed that the optimal length is similar for the working conditions considered. As a result of this study, it is found that this innovative receiver provides an optimum design for the whole day, even though impinging radiation intensity varies notably. Thermal features of this type of receiver could be the base of a new generation of concentrated solar power plants with a great potential for cost reduction, because of the simplicity of the system and the lower weigh of the

  18. Sustainable urban regime adjustments

    DEFF Research Database (Denmark)

    Quitzau, Maj-Britt; Jensen, Jens Stissing; Elle, Morten

    2013-01-01

    The endogenous agency that urban governments increasingly portray by making conscious and planned efforts to adjust the regimes they operate within is currently not well captured in transition studies. There is a need to acknowledge the ambiguity of regime enactment at the urban scale. This direc...

  19. Study of the laser-induced damage of reflective components in the sub-picosecond regime

    International Nuclear Information System (INIS)

    Sozet, Martin

    2016-01-01

    In this thesis, laser-induced damage phenomenon of reflective components is investigated in the sub-picosecond regime. These components, made of stacks of dielectric materials, are widely used in powerful laser facilities such as PETAL laser. PETAL laser has been built at the CEA-CESTA in France to deliver multi-kJ/500 fs pulses at 1053 nm and reach a power higher than 6 PW. For this kind of laser systems, reflective components are commonly used instead of optics operating in transmission to limit the accumulation of non-linear phase along the beam propagation due to the high intensities. Optical components irradiated by the highest power densities are the pulse compression gratings, transport mirrors and the focusing parabola, located at the end of the laser chain. Nowadays, laser-induced damage is the main factor that limits the overall performances of powerful laser systems. This manuscript presents three study axes to better understand and control damage phenomenon. The first one concerns the conception of reflective optics for the peta-watt applications. The design of new structures has been investigated to reach high diffraction efficiencies in the case of pulse compression gratings and a high reflectivity in the case of mirrors, while reducing the Electric-field enhancement which is one of the causes of the laser-induced damage. The second axis deals with the development of a precise damage metrology with new testing tools which brings new perspectives and a new viewpoint for the assessment of the laser resistance of optical components. Finally, the third axis concerns the study the damage growth after several irradiations in the sub-picosecond regime. The evolution of the damage area during growth sequences is observed and compared to numerical simulations. It enables to improve the understanding in the growth phenomenon. In the end, these studies will allow to develop predictive models of the laser-induced damage and new tools for the conception of

  20. Numerical study of the bubbly flow regime in micro-channel flow boiling

    Science.gov (United States)

    Bhuvankar, Pramod; Dabiri, Sadegh

    2017-11-01

    Two-phase flow accompanied by boiling in micro-channel heat sinks is an effective means for heat removal from computer chips. We present a numerical study of flow boiling in micro-channels with conjugate heat transfer with a focus on the bubbly flow regime. The bubbles are assumed to nucleate at a pre-determined location and frequency. The Navier Stokes equations are solved using a single fluid formulation with the Front tracking method. Phase change is implemented using the deficit in heat flux across the bubble interface. The analytical solution for bubble growth in a superheated liquid is used as a benchmark to validate the mentioned numerical method. Water and FC-72 are studied as the operating fluids in a micro-channel made of Copper with a focus on hotspot mitigation. The micro-channel of cross-section 231 μm × 1000 μm , is used to study the effects of vertical up-flow, vertical down-flow and horizontal flow of the mentioned fluids on the heat transfer coefficients. A simple film model accounting for mass and energy conservation is applied wherever the bubble approaches closer than a cell width to the wall. The results of the simulation are compared with existing experimental data for bubble growth rates and heat transfer coefficients.

  1. Study of volume fractions on biphasic stratified regime using gamma ray

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, William L.; Brandão, Luis E.B., E-mail: william.otero@hotmail.com, E-mail: brandao@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2017-07-01

    In the oil industries, interconnected pipelines are used to carry large quantities of petroleum and its byproducts. This modal has an advantage because they are more economical, eliminate a need for stocks and, in addition, great safety in operation minimizing a possibility of loss or theft when transported another way. In many cases, especially in the petrochemical industry, the same pipeline is used to carry more than one type of product. They are called poliduct. In the operation of a poliduct there is a sequence of products to be transported and during the exchange of the product, there are still fractions of the previous product and this generates contamination. It is therefore important to identify precisely this region in order to reduce the costs of reprocessing and treatment of discarded products. In this way, this work presents a methodology to evaluate the sensitivity of the gamma densitometry technique in a study of the calculation of volume fractions in biphasic systems, submitted to the stratified flow regime. Using computational simulations using the Monte Carlo Method with the MCNPX code measurement geometry was proposed that presented a higher sensitivity for the calculation of volume fractions. The relevant technical data to perform a simulation of the scintillator detectors were based on information obtained from the gammagraphy technique. The study had a theoretical validation through analytical equations, and the results show that it is possible to identify volume fractions equivalent to 3%. (author)

  2. Study of volume fractions on biphasic stratified regime using gamma ray

    International Nuclear Information System (INIS)

    Salgado, William L.; Brandão, Luis E.B.

    2017-01-01

    In the oil industries, interconnected pipelines are used to carry large quantities of petroleum and its byproducts. This modal has an advantage because they are more economical, eliminate a need for stocks and, in addition, great safety in operation minimizing a possibility of loss or theft when transported another way. In many cases, especially in the petrochemical industry, the same pipeline is used to carry more than one type of product. They are called poliduct. In the operation of a poliduct there is a sequence of products to be transported and during the exchange of the product, there are still fractions of the previous product and this generates contamination. It is therefore important to identify precisely this region in order to reduce the costs of reprocessing and treatment of discarded products. In this way, this work presents a methodology to evaluate the sensitivity of the gamma densitometry technique in a study of the calculation of volume fractions in biphasic systems, submitted to the stratified flow regime. Using computational simulations using the Monte Carlo Method with the MCNPX code measurement geometry was proposed that presented a higher sensitivity for the calculation of volume fractions. The relevant technical data to perform a simulation of the scintillator detectors were based on information obtained from the gammagraphy technique. The study had a theoretical validation through analytical equations, and the results show that it is possible to identify volume fractions equivalent to 3%. (author)

  3. Is science the driving force in the operation of environmental regimes? : A case study of the Mediterranean Action Plan

    NARCIS (Netherlands)

    Frantzi, Sofia; Lovett, Jonathan Cranidge

    2008-01-01

    This study examines the role of science in the operation of environmental regimes using the Barcelona Convention/Mediterranean Action Plan (MAP) as a case study. The ‘epistemic communities’ theory suggests that emergence of the Mediterranean Action Plan was largely driven by scientific experts. In

  4. Is science the driving force in the operation of environmental regimes? A case study of the Mediterranean Action Plan

    NARCIS (Netherlands)

    Frantzi, Sofia; Lovett, Jonathan Cranidge

    2008-01-01

    This study examines the role of science in the operation of environmental regimes using the Barcelona Convention/Mediterranean Action Plan (MAP) as a case study. The ‘epistemic communities’ theory suggests that emergence of the Mediterranean Action Plan was largely driven by scientific experts. In

  5. Is science the driving force in the operation of environmental regimes? A case study of the Mediterranean Action Plan

    NARCIS (Netherlands)

    Frantzi, S.; Lovett, J.C.

    2008-01-01

    This study examines the role of science in the operation of environmental regimes using the Barcelona Convention/Mediterranean Action Plan (MAP) as a case study. The 'epistemic communities' theory suggests that emergence of the Mediterranean Action Plan was largely driven by scientific experts. In

  6. A Prospective Comparative Study of the Toxicity Profile of 5-Flurouracil, Adriamycin, Cyclophosphamide Regime VS Adriamycin, Paclitaxel Regime in Patients with Locally Advanced Breast Carcinoma

    Science.gov (United States)

    Pillai, Pradeep Sadasivan; Jayakumar, Krishnan Nair Lalithamma

    2015-01-01

    Introduction A 5-flurouracil, Adriamycin, Cyclophosphamide (FAC) and Adriamycin, Paclitaxel (AT) are two popular chemotherapeutic regimens for treatment of breast carcinoma. The most time tested and popular regimen is FAC. It is extensively studied for efficacy and toxicity. But data regarding toxicity profile and efficacy of AT regimen is sparse. Aim To study the toxicity profile, severity of toxicities and clinical response rate of FAC and AT regimens in patients with locally advanced breast carcinoma. Materials and Methods A prospective observational study with 50 patients in each treatment arm. Study duration was 12 months from November 2012 to October 2013. Consecutive patients with locally advanced breast carcinoma receiving treatment with either FAC or AT regimen, satisfying inclusion criteria were enrolled into the study after getting informed written consent. Prior to initiation of treatment detailed medical history was taken from all patients. General clinical examination, examination of organ systems and local examination of breast lump were done. After each cycle of chemotherapy and after completion of treatment patients were interviewed and examined for clinical response and toxicities. Toxicities were graded with WHO toxicity grading criteria. All data were entered in a structured proforma. At least 50% reduction in tumour size was taken as adequate clinical response. Statistical Analysis Data was analysed using Chi-square test with help of Excel 2007 and SPSS-16 statistical software. Results Different pattern of toxicities were seen with FAC and AT regimens. Anaemia, thrombocytopenia, stomatitis, hyperpigmentation, photosensitivity and diarrhoea were more common with patients receiving FAC regimen. Leucopenia, peripheral neuropathy, myalgia, arthralgia, vomiting and injection site reactions were more common in AT regimen. Both FAC and AT regimens gave 100% clinical response. Conclusion FAC and AT regimens are equally efficacious but have different

  7. Design and optical performance of a nonimaging Fresnel transmissive concentrator for building integration applications

    Energy Technology Data Exchange (ETDEWEB)

    Chemisana, Daniel, E-mail: daniel.chemisana@macs.udl.cat [Applied Physics Section of the Polytechnic School (EPS), University of Lleida, 25001 Lleida (Spain); Ignasi Rosell, Joan [Applied Physics Section of the Polytechnic School (EPS), University of Lleida, 25001 Lleida (Spain)

    2011-09-15

    Highlights: {yields} The designed concentrator has an important potential for building integration. {yields} The device concentrates radiation toward a static receiver. {yields} Tracking performed by a single driver, representing an important mechanical advantage. {yields} The system reaches a global optical efficiency value of 56.38%. - Abstract: A transmissive Fresnel reflector is designed to match the needs of building integration for concentrating photovoltaic (PV), thermal (T) or hybrid photovoltaic/thermal (PVT) generation. The device concentrates radiation toward a static receiver by means of an array of reflectors which rotate collectively. All rotation axes are coplanar and parallel. A deep analytical ray tracing study has been made of the design characteristics and concentrator performance, thus determining the configuration which optimises efficiency. Numerous ray tracing numerical simulations have been performed which contrast and support the analytical results.

  8. Design and optical performance of a nonimaging Fresnel transmissive concentrator for building integration applications

    International Nuclear Information System (INIS)

    Chemisana, Daniel; Ignasi Rosell, Joan

    2011-01-01

    Highlights: → The designed concentrator has an important potential for building integration. → The device concentrates radiation toward a static receiver. → Tracking performed by a single driver, representing an important mechanical advantage. → The system reaches a global optical efficiency value of 56.38%. - Abstract: A transmissive Fresnel reflector is designed to match the needs of building integration for concentrating photovoltaic (PV), thermal (T) or hybrid photovoltaic/thermal (PVT) generation. The device concentrates radiation toward a static receiver by means of an array of reflectors which rotate collectively. All rotation axes are coplanar and parallel. A deep analytical ray tracing study has been made of the design characteristics and concentrator performance, thus determining the configuration which optimises efficiency. Numerous ray tracing numerical simulations have been performed which contrast and support the analytical results.

  9. Fringe-tunable electrothermal Fresnel mirror for use in compact and high-speed diffusion sensor.

    Science.gov (United States)

    Kiuchi, Yuki; Taguchi, Yoshihiro; Nagasaka, Yuji

    2017-01-23

    This paper reports the development of an electrothermal microelectromechanical systems (MEMS) mirror with serpentine shape actuators. A micro Fresnel mirror with fringe-spacing tunability is required to realize a compact and high-speed diffusion sensor for biological samples whose diffusion coefficient changes significantly because of a conformational change. In this case, the measurement time-constant is dependent on the fringe-spacing and diffusion coefficient of the sample. In this study, a fringe-tunable MEMS mirror with an actuation voltage less than 10 V was developed. The characteristics of the fabricated mirror were investigated experimentally. A high-visibility optical interference fringe was successfully demonstrated using both an ultranarrow-linewidth solid-state laser and a low-cost compact laser diode. The experimental results demonstrated a distinct possibility of developing a measurement device using only simple and low-voltage optical components.

  10. Observational and numerical study of the Vardaris wind regime in northern Greece

    Science.gov (United States)

    Koletsis, I.; Giannaros, T. M.; Lagouvardos, K.; Kotroni, V.

    2016-05-01

    The Axios Valley, located in central-northern Greece, is surrounded by complex topography that plays a significant role in the modification of wind flow, both in terms of speed and direction. The characteristic wind regime of this valley is Vardaris, a northwesterly wind that prevails in this region, especially during the cold period of the year. Vardaris is well known for its consistent direction and high intensity, as well as for the effective advection of cold and dry air, often resulting to significant damages in local infrastructures and agriculture. A field campaign under the name AXIOS took place during the period from November 2007 through May 2008 in order to examine this particular wind flow. The analysis of the in situ observational data, which was funded by the research program THESPIA-KRIPIS, showed that topography plays a key role in intensifying Vardaris, generating gusts that approximated 30 m s- 1 during the experimental period. The air temperature and humidity fields were also found to be significantly influenced. In addition to the observational study, an intense Vardaris episode was simulated with the Weather Research and Forecasting (WRF) model at high horizontal resolution. Results revealed that the model was able to reproduce the favorable environmental conditions that lead to Vardaris occurrence, providing a useful insight on the physical mechanisms explaining its structure.

  11. A Study on the Improvement of Nuclear Forensics Legal Regime in Korea

    International Nuclear Information System (INIS)

    Lee, Jung Hyun; Baek, Ye Ji; Kim, Jae Kwang; Chang, Sun Young; Hwang, Yong Soo

    2016-01-01

    Nuclear forensics is a critical component of security of these materials and an effective investigatory tool in providing evidence for the prosecution of these malicious acts related to the illicit materials. Because nuclear forensic enhances a State's ability to assess and establish linkages between nuclear and radioactive materials, and those who have attempted to transport, possess, or use it without legitimate State control. However, nuclear forensics is not yet reflected in the domestic laws. Therefore, in this study, we examined related international laws and other important efforts. We compared legal regime improvement options between amending existing legislations and introducing new legislation. Then, based on the analysis, we suggested draft provisions of highest level national legislation on nuclear forensics. We reviewed the analysis of international laws and other important efforts on nuclear forensics to improve of domestic legislations on the nuclear forensics. Through the review of current international movement on the nuclear forensics, we concluded as follows; (a) The state government must be responsible for the nuclear forensics (b) Appropriate administrative regulations on nuclear forensics is required within the highest level legislation

  12. A Study on the Improvement of Nuclear Forensics Legal Regime in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jung Hyun; Baek, Ye Ji; Kim, Jae Kwang; Chang, Sun Young; Hwang, Yong Soo [Korea Institute of Nuclear Nonproliferation and Control, Daejeon (Korea, Republic of)

    2016-05-15

    Nuclear forensics is a critical component of security of these materials and an effective investigatory tool in providing evidence for the prosecution of these malicious acts related to the illicit materials. Because nuclear forensic enhances a State's ability to assess and establish linkages between nuclear and radioactive materials, and those who have attempted to transport, possess, or use it without legitimate State control. However, nuclear forensics is not yet reflected in the domestic laws. Therefore, in this study, we examined related international laws and other important efforts. We compared legal regime improvement options between amending existing legislations and introducing new legislation. Then, based on the analysis, we suggested draft provisions of highest level national legislation on nuclear forensics. We reviewed the analysis of international laws and other important efforts on nuclear forensics to improve of domestic legislations on the nuclear forensics. Through the review of current international movement on the nuclear forensics, we concluded as follows; (a) The state government must be responsible for the nuclear forensics (b) Appropriate administrative regulations on nuclear forensics is required within the highest level legislation.

  13. Nonimaging fresnel lenses. Design and performance of solar concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Leutz, R. [Tokyo Univ. of Agriculture and Technology, Koganei-shi (Japan). BASE; Suzuki, A. [UNESCO, Paris (France). Natural Science Sector

    2001-07-01

    This book offers a detailed and comprehensive account of the engineering of the world's first nonimaging Fresnel lens solar concentrator. The book closes a gap in solar concentrator design, and describes nonimaging refractive optics and its numerical mathematics. The contents follow a systems approach that is absent in standard handbooks of optics or solar energy. The reader is introduced to the principles, theories, and advantages of nonimaging optics from the standpoint of concentrating sunlight (the solar concentrator idea). The book shows the reader how to find his or her own optical solution using the rules and methodologies covering the design and the assessment of the nonimaging lens. This novel solar concentrator is developed within the natural constraints presented by the sun and in relation to competitive solutions offered by other concentrators. (orig.)

  14. A Fresnel collector process heat experiment at Capitol Concrete Products

    Science.gov (United States)

    Hauger, J. S.

    1981-01-01

    An experiment is planned, conducted and evaluated to determine the feasibility of using a Power Kinetics' Fresnel concentrator to provide process heat in an industrial environment. The plant provides process steam at 50 to 60 psig to two autoclaves for curing masonry blocks. When steam is not required, the plant preheats hot water for later use. A second system is installed at the Jet Propulsion Laboratory parabolic dish test site for hardware validation and experiment control. Experiment design allows for the extrapolation of results to varying demands for steam and hot water, and includes a consideration of some socio-technical factors such as the impact on production scheduling of diurnal variations in energy availability.

  15. Fabrication and characterization of InP fresnel microlenses

    International Nuclear Information System (INIS)

    Diadiuk, V.; Walpole, J.N.; Liau, Z.L.

    1987-01-01

    Since diode lasers typically have a beam divergence of a few tens of degrees, collimating the laser outputs leads to greatly far-field patterns, which, in turn translates into more power in the main lobe of the combined output. Achieving this collimation in the case of a diode laser array, with its small device-to-device distance, requires an array of similarly spaced microlenses with very short focal length, small diameter and small F number. In this paper, the authors describe the fabrication and performance of a Fresnel microlens array etched directly in InP wafers; these microlenses have been used successfully to collimate the output of GainAsP/InP buried-heterostructure (BH) diode lasers

  16. Solar-pumped 80 W laser irradiated by a Fresnel lens.

    Science.gov (United States)

    Ohkubo, Tomomasa; Yabe, Takashi; Yoshida, Kunio; Uchida, Shigeaki; Funatsu, Takayuki; Bagheri, Behgol; Oishi, Takehiro; Daito, Kazuya; Ishioka, Manabu; Nakayama, Yuichirou; Yasunaga, Norihito; Kido, Kouichirou; Sato, Yuji; Baasandash, Choijil; Kato, Kiyoshi; Yanagitani, Takagimi; Okamoto, Yoshiaki

    2009-01-15

    A solar-pumped 100 W class laser that features high efficiency and low cost owing to the use of a Fresnel lens and a chromium codoped neodymium YAG ceramic laser medium was developed. A laser output of about 80 W was achieved with combination of a 4 m(2) Fresnel lens and a pumping cavity as a secondary power concentrator. This output corresponds to 4.3% of conversion efficiency from solar power into laser, and the maximum output from a unit area of Fresnel lens was 20 W/m(2), which is 2.8 times larger than previous results with mirror-type concentrator.

  17. Design and Optimization of Fresnel Lens for High Concentration Photovoltaic System

    Directory of Open Access Journals (Sweden)

    Lei Jing

    2014-01-01

    Full Text Available A practical optimization design is proposed, in which the solar direct light spectrum and multijunction cell response range are taken into account in combination, particularly for the Fresnel concentrators with a high concentration and a small aspect ratio. In addition, the change of refractive index due to temperature variation in outdoor operation conditions is also considered in the design stage. The calculation results show that this novel Fresnel lens achieves an enhancement of energy efficiency of about 10% compared with conventional Fresnel lens for a given solar spectrum, solar cell response, and corrected sunshine hours of different ambient temperature intervals.

  18. Active liquid-crystal deflector and lens with Fresnel structure

    Science.gov (United States)

    Shibuya, Giichi; Yamano, Shohei; Yoshida, Hiroyuki; Ozaki, Masanori

    2017-02-01

    A new type of tunable Fresnel deflector and lens composed of liquid crystal was developed. Combined structure of multiple interdigitated electrodes and the high-resistivity (HR) layer implements the saw-tooth distribution of electrical potential with only the planar surfaces of the transparent substrates. According to the numerical calculation and design, experimental devices were manufactured with the liquid crystal (LC) material sealed into the sandwiched flat glass plates of 0.7 mm thickness with rubbed alignment layers set to an anti-parallel configuration. Fabricated beam deflector with no moving parts shows the maximum tilt angle of +/-1.3 deg which can apply for optical image stabilizer (OIS) of micro camera. We also discussed and verified their lens characteristics to be extended more advanced applications. Transparent interdigitated electrodes were concentrically aligned on the lens aperture with the insulator gaps under their boundary area. The diameter of the lens aperture was 30 mm and the total number of Fresnel zone was 100. Phase retardation of the beam wavefront irradiated from the LC lens device can be evaluated by polarizing microscope images with a monochromatic filter. Radial positions of each observed fringe are plotted and fitted with 2nd degree polynomial approximation. The number of appeared fringes is over 600 in whole lens aperture area and the correlation coefficients of all approximations are over 0.993 that seems enough ideal optical wavefront. The obtained maximum lens powers from the approximations are about +/-4 m-1 which was satisfied both convex and concave lens characteristics; and their practical use for the tunable lens grade eyeglasses became more prospective.

  19. Fast generation of Fresnel holograms based on multirate filtering.

    Science.gov (United States)

    Tsang, Peter; Liu, Jung-Ping; Cheung, Wai-Keung; Poon, Ting-Chung

    2009-12-01

    One of the major problems in computer-generated holography is the high computation cost involved for the calculation of fringe patterns. Recently, the problem has been addressed by imposing a horizontal parallax only constraint whereby the process can be simplified to the computation of one-dimensional sublines, each representing a scan plane of the object scene. Subsequently the sublines can be expanded to a two-dimensional hologram through multiplication with a reference signal. Furthermore, economical hardware is available with which sublines can be generated in a computationally free manner with high throughput of approximately 100 M pixels/second. Apart from decreasing the computation loading, the sublines can be treated as intermediate data that can be compressed by simply downsampling the number of sublines. Despite these favorable features, the method is suitable only for the generation of white light (rainbow) holograms, and the resolution of the reconstructed image is inferior to the classical Fresnel hologram. We propose to generate holograms from one-dimensional sublines so that the above-mentioned problems can be alleviated. However, such an approach also leads to a substantial increase in computation loading. To overcome this problem we encapsulated the conversion of sublines to holograms as a multirate filtering process and implemented the latter by use of a fast Fourier transform. Evaluation reveals that, for holograms of moderate size, our method is capable of operating 40,000 times faster than the calculation of Fresnel holograms based on the precomputed table lookup method. Although there is no relative vertical parallax between object points at different distance planes, a global vertical parallax is preserved for the object scene as a whole and the reconstructed image can be observed easily.

  20. Regime change?

    International Nuclear Information System (INIS)

    Pilat, Joseph F.; Budlong-Sylvester, K.W.

    2004-01-01

    Following the 1998 nuclear tests in South Asia and later reinforced by revelations about North Korean and Iraqi nuclear activities, there has been growing concern about increasing proliferation dangers. At the same time, the prospects of radiological/nuclear terrorism are seen to be rising - since 9/11, concern over a proliferation/terrorism nexus has never been higher. In the face of this growing danger, there are urgent calls for stronger measures to strengthen the current international nuclear nonproliferation regime, including recommendations to place civilian processing of weapon-useable material under multinational control. As well, there are calls for entirely new tools, including military options. As proliferation and terrorism concerns grow, the regime is under pressure and there is a temptation to consider fundamental changes to the regime. In this context, this paper will address the following: Do we need to change the regime centered on the Treaty on the Nonproliferation of Nuclear Weapons (NPT) and the International Atomic Energy Agency (IAEA)? What improvements could ensure it will be the foundation for the proliferation resistance and physical protection needed if nuclear power grows? What will make it a viable centerpiece of future nonproliferation and counterterrorism approaches?

  1. Experimental and numerical investigation of a linear Fresnel solar collector with flat plate receiver

    International Nuclear Information System (INIS)

    Bellos, Evangelos; Mathioulakis, Emmanouil; Tzivanidis, Christos; Belessiotis, Vassilis; Antonopoulos, Kimon A.

    2016-01-01

    Highlights: • A linear Fresnel solar collector with flat plate receiver is investigated. • The collector is investigated experimentally in energetic and exergetic terms. • The developed numerical model is validated with the experimental results. • The operation with thermal oil is also examined with the developed model. • The final results prove satisfying performance for medium temperature levels. - Abstract: In this study a linear Fresnel solar collector with flat plate receiver is investigated experimentally and numerically with Solidworks Flow Simulation. The developed model combines optical, thermal and flow analysis; something innovative and demanding which leads to accurate results. The main objective of this study is to determine the thermal, the optical and the exergetic performance of this collector in various operating conditions. For these reasons, the developed model is validated with the respective experimental data and after this step, the solar collector model is examined parametrically for various fluid temperature levels and solar incident angles. The use of thermal oil is also analyzed with the simulation tool in order to examine the collector performance in medium temperature levels. The experiments are performed with water as working fluid and for low temperature levels up to 100 °C. The final results proved that this solar collector is able to produce about 8.5 kW useful heat in summer, 5.3 kW in spring and 2.9 kW in winter. Moreover, the operation of this collector with thermal oil can lead to satisfying results up to 250 °C.

  2. Studies on Ytterbium-doped Fibre Laser Operating in Different Regimes

    International Nuclear Information System (INIS)

    Gan, Y; Xiang, W H; Zhang, G Z

    2006-01-01

    An ytterbium-doped fibre laser with a unidirectional ring cavity containing a polarizer placed between two in-line polarization controllers is presented. Depending on an equivalent saturable absorber, this laser operates in continuous, Q-switched mode-locked or CW mode-locked regimes. The passive method described here allowed us to choose the operating regime of the fibre laser by rotating the two polarization controllers and adjusting the pump power. Results of numerical simulations of pulse propagation in such a mode-locked fibre ring laser are presented, which reveals that the Q-switched mode-locked or CW modelocked regimes can be achieved by aligning the polarizer near the slow or the fast axes of the fibre

  3. Study of Material Densification of In718 in the Higher Throughput Parameter Regime

    Science.gov (United States)

    Cordner, Samuel

    2016-01-01

    Selective Laser Melting (SLM) is a powder bed fusion additive manufacturing process used increasingly in the aerospace industry to reduce the cost, weight, and fabrication time for complex propulsion components. Previous optimization studies for SLM using the Concept Laser M1 and M2 machines at NASA Marshall Space Flight Center have centered on machine default parameters. The objective of this project is to characterize how heat treatment affects density and porosity from a microscopic point of view. This is performs using higher throughput parameters (a previously unexplored region of the manufacturing operating envelope for this application) on material consolidation. Density blocks were analyzed to explore the relationship between build parameters (laser power, scan speed, and hatch spacing) and material consolidation (assessed in terms of density and porosity). The study also considers the impact of post-processing, specifically hot isostatic pressing and heat treatment, as well as deposition pattern on material consolidation in the higher energy parameter regime. Metallurgical evaluation of specimens will also be presented. This work will contribute to creating a knowledge base (understanding material behavior in all ranges of the AM equipment operating envelope) that is critical to transitioning AM from the custom low rate production sphere it currently occupies to the world of mass high rate production, where parts are fabricated at a rapid rate with confidence that they will meet or exceed all stringent functional requirements for spaceflight hardware. These studies will also provide important data on the sensitivity of material consolidation to process parameters that will inform the design and development of future flight articles using SLM.

  4. Assessing flow regime alterations in a temporary river – the River Celone case study

    Directory of Open Access Journals (Sweden)

    De Girolamo Anna Maria

    2015-09-01

    Full Text Available In this paper, we present an approach to evaluate the hydrological alterations of a temporary river. In these rivers, it is expected that anthropogenic pressures largely modify low-flow components of the flow regime with consequences for aquatic habitat and diversity in invertebrate species. First, by using a simple hydrological index (IARI river segments of the Celone stream (southern Italy whose hydrological regime is significantly influenced by anthropogenic activities have been identified. Hydrological alteration has been further classified through the analysis of two metrics: the degree (Mf and the predictability of dry flow conditions (Sd6. Measured streamflow data were used to calculate the metrics in present conditions (impacted. Given the lack of data from pristine conditions, simulated streamflow time series were used to calculate the metrics in reference conditions. The Soil and Water Assessment Tool (SWAT model was used to estimate daily natural streamflow. Hydrological alterations associated with water abstractions, point discharges and the presence of a reservoir were assessed by comparing the metrics (Mf, Sd6 before and after the impacts. The results show that the hydrological regime of the river segment located in the upper part of the basin is slightly altered, while the regime of the river segment downstream of the reservoir is heavily altered. This approach is intended for use with ecological metrics in defining the water quality status and in planning streamflow management activities.

  5. A law & economics approach to the study of integrated management regimes of estuaries

    NARCIS (Netherlands)

    van de Griendt, W.E.

    2004-01-01

    In this paper it is proposed to analyse legal regimes for integrated management of estuaries with the help of institutional legal theory and the Schlager & Ostrom framework for types of ownership. Estuaries are highly valued and valuable and therefore need protection. The problem is that they

  6. Review of studies on conventional linear colliders in the S- and X-Band regime

    International Nuclear Information System (INIS)

    Loew, G.A.

    1992-07-01

    This paper gives a status report on the conventional approaches to linear colliders at DESY, KEK, SLAC and INP-Protvino in the S- and X-Band regime. Critical topics are reviewed and a discussion of global issues such as future R ampersand D requirements is included

  7. Evaluation of Fresnel's corrections to the eikonal approximation by the separabilization method

    International Nuclear Information System (INIS)

    Musakhanov, M.M.; Zubarev, A.L.

    1975-01-01

    Method of separabilization of potential over the Schroedinger approximate solutions, leading to Schwinger's variational principle for scattering amplitude, is suggested. The results are applied to calculation of the Fresnel corrections to the Glauber approximation

  8. Graphical Approach to Fresnel's Equations for Reflection and Refraction of Light.

    Science.gov (United States)

    Doyle, William T.

    1980-01-01

    Develops a coordinate-free approach to Fresnel's equations for the reflection and refraction of light at a plane interface. Describes a graphical construction for finding the vector amplitudes of the reflected and transmitted waves. (Author/CS)

  9. Flux-redistribution in the focal region of a planar Fresnel ring mirror

    Energy Technology Data Exchange (ETDEWEB)

    Sastroamidjojo, M.S.A. (Gadjah Mada Univ., Indonesia); Lubis, W.

    1979-01-01

    The results of an investigation of flux redistribution at the focal region of a planar Fresnel ring mirror are reported. A parabolic mirror of large aperture was used to provide a parallel beam of light which was directed at the Fresnel test object. A cotton thread grid was used as a mapping aid to provide a 25 x 25 matrix of spatial data points. (SPH)

  10. Quantum correspondence of the mixed Lenz-Fresnel transform in classical optics

    International Nuclear Information System (INIS)

    Fan Hongyi; Tang Xubing; Lu Hailiang

    2006-01-01

    We find the quantum correspondence (a four-parameter squeezing operator U(r,s,μ)) of the mixed optical Lenz-Fresnel transform, i.e. that the kernel of Lenz-Fresnel transform is just the matrix element of U(r,s,μ) in the entangled states. The group multiplication rule of U(r,s,μ) is proved by virtue of its coherent entangled state representation which is essential to this correspondence

  11. Interpretation of interfacial structures in X-ray multilayers by TEM Fresnel fringe effects

    OpenAIRE

    Nguyen, Tai D.; O'Keefe, Michael A.; Kilaas, Roar; Gronsky, Ronald; Kortright, Jeffrey B.

    1991-01-01

    Assessment of interfacial structures from high-resolution TEM images of cross-sectional specimens is difficult due to Fresnel fringe effects producing different apparent structures in the images. The effects of these fringes have been commonly over-looked in efforts of making quantitative interpretation of interfacial profiles. In this report, we present the observations of the Fresnel fringes in nanometer period Mo/Si, W/C, and WC/C multilayers in through-focus-series TEM images. Calculation...

  12. Electrically switchable holographic liquid crystal/polymer Fresnel lens using a Michelson interferometer.

    Science.gov (United States)

    Jashnsaz, Hossein; Mohajerani, Ezeddin; Nemati, Hossein; Razavi, Seyed Hossein; Alidokht, Isa Ahmad

    2011-06-10

    A holographic technique for fabricating an electrically switchable liquid crystal/polymer composite Fresnel lens is reported. A Michelson interferometer is used to produce the required Fresnel pattern, by placing a convex lens into one path of the interferometer. Simplicity of the method and the possibility of fabricating different focal length lenses in a single arrangement are advantages of the method. The performance of the fabricated lens was demonstrated and its electro-optical properties were investigated for its primary focal length.

  13. Experimental study of linear and nonlinear regimes of density-driven instabilities induced by CO2 dissolution in water

    International Nuclear Information System (INIS)

    Outeda, R.; D'Onofrio, A.; El Hasi, C.; Zalts, A.

    2014-01-01

    Density driven instabilities produced by CO 2 (gas) dissolution in water containing a color indicator were studied in a Hele Shaw cell. The images were analyzed and instability patterns were characterized by mixing zone temporal evolution, dispersion curves, and the growth rate for different CO 2 pressures and different color indicator concentrations. The results obtained from an exhaustive analysis of experimental data show that this system has a different behaviour in the linear regime of the instabilities (when the growth rate has a linear dependence with time), from the nonlinear regime at longer times. At short times using a color indicator to see the evolution of the pattern, the images show that the effects of both the color indicator and CO 2 pressure are of the same order of magnitude: The growth rates are similar and the wave numbers are in the same range (0–30 cm −1 ) when the system is unstable. Although in the linear regime the dynamics is affected similarly by the presence of the indicator and CO 2 pressure, in the nonlinear regime, the influence of the latter is clearly more pronounced than the effects of the color indicator

  14. A case for studying country regimes in the public health model of violence.

    Science.gov (United States)

    Gilligan, James; Lee, Bandy X; Garg, Shikha; Blay-Tofey, Morkeh; Luo, Audrey

    2016-09-01

    Many national and international institutions advocate approaching violence as a problem in public health and preventive medicine, in a manner similar to the way we address other disabling and life-threatening pathologies such as cancer, diabetes, and heart disease. Prevention by a health model requires an ecological perspective. Previous work has found evidence that economic factors, including unemployment and relative poverty, as well as political culture and values, may affect violent death rates, including homicide and suicide. Nevertheless, wider political analyses of the effects that different regimes have on these variables have been notably absent, for understandable reasons given the sheer complexity of patterns of governance throughout the world. In view of the importance and scale of the problem, and implications of the United Nations' 2030 Agenda for Sustainable Development, we feel it is nevertheless important to bring regime types into the conversation of factors that can influence violent death.

  15. Static Linear Fresnel Lenses as LCPV System in a Greenhouse

    Science.gov (United States)

    Sonneveld, P. J.; Swinkels, G. L. A. M.; van Tuijl, B. A. J.; Janssen, H. J. J.; de Zwart, H. F.

    2011-12-01

    A low concentrating PV system with water cooling (LCPVT system) will result in electrical and thermal energy output from the solar energy excess entering a building or greenhouse. All the direct radiation could be converted, which corresponds to 75% of the incoming solar energy. This will significantly reduce the demand of cooling of the building. For an optimal performance it is beneficial to construct asymmetric roof elements with a steep inclination at the north side (the exact angle of course depends on the latitude of the building site). The Fresnel lens structure is oriented in upwards direction. In the current design, two of them are placed between an AR-coated double glass structure to prevent pollution and condensation on the lenses. Compared with a previous system, the number of lenses is reduced from 3 to 2 lenses, which reduces the costs of the system by limiting the number of receivers. By the upward facing of the lens structure, the focus quality is preserved over a much broader range of angles of incidence compared to a lens with downward facing structures. Each PMMA lens with a size of 1.20 m×1.60 m is composed of 12 `tiles' for easy production. The focal distance of the lens is 1,875 m and the concentration factor 50x. In most cases the focus line is thinner than 3 cm and the transmission is above 80%. The performance of these lenses with respect of the shape of the focal area and the position of the focal line has been analyzed with ray tracing techniques. From this analyses it was concluded that tracking of the receiver module is possible with two motors. One motor controls the distance between lens and receiver and one motor controls the translocation of the receivers parallel to the lens. The second conclusion was that the positions of the focal line are within the bounds of the greenhouse construction for almost the whole year. Only in winter, the focal line will be unreachable from time to time. A 480 m2 greenhouse with the LCPVT system

  16. High precision refractometry based on Fresnel diffraction from phase plates.

    Science.gov (United States)

    Tavassoly, M Taghi; Naraghi, Roxana Rezvani; Nahal, Arashmid; Hassani, Khosrow

    2012-05-01

    When a transparent plane-parallel plate is illuminated at a boundary region by a monochromatic parallel beam of light, Fresnel diffraction occurs because of the abrupt change in phase imposed by the finite change in refractive index at the plate boundary. The visibility of the diffraction fringes varies periodically with changes in incident angle. The visibility period depends on the plate thickness and the refractive indices of the plate and the surrounding medium. Plotting the phase change versus incident angle or counting the visibility repetition in an incident-angle interval provides, for a given plate thickness, the refractive index of the plate very accurately. It is shown here that the refractive index of a plate can be determined without knowing the plate thickness. Therefore, the technique can be utilized for measuring plate thickness with high precision. In addition, by installing a plate with known refractive index in a rectangular cell filled with a liquid and following the described procedures, the refractive index of the liquid is obtained. The technique is applied to measure the refractive indices of a glass slide, distilled water, and ethanol. The potential and merits of the technique are also discussed.

  17. Thin Fresnel zone plate lenses for focusing underwater sound

    International Nuclear Information System (INIS)

    Calvo, David C.; Thangawng, Abel L.; Nicholas, Michael; Layman, Christopher N.

    2015-01-01

    A Fresnel zone plate (FZP) lens of the Soret type creates a focus by constructive interference of waves diffracted through open annular zones in an opaque screen. For underwater sound below MHz frequencies, a large FZP that blocks sound using high-impedance, dense materials would have practical disadvantages. We experimentally and numerically investigate an alternative approach of creating a FZP with thin (0.4λ) acoustically opaque zones made of soft silicone rubber foam attached to a thin (0.1λ) transparent rubber substrate. An ultra-thin (0.0068λ) FZP that achieves higher gain is also proposed and simulated which uses low-volume fraction, bubble-like resonant air ring cavities to construct opaque zones. Laboratory measurements at 200 kHz indicate that the rubber foam can be accurately modeled as a lossy fluid with an acoustic impedance approximately 1/10 that of water. Measured focal gains up to 20 dB agree with theoretical predictions for normal and oblique incidence. The measured focal radius of 0.68λ (peak-to-null) agrees with the Rayleigh diffraction limit prediction of 0.61 λ/NA (NA = 0.88) for a low-aberration lens

  18. An Electron-Beam Profile Monitor Using Fresnel Zone Plates

    International Nuclear Information System (INIS)

    Nakamura, Norio; Sakai, Hiroshi; Iida, Kensuke; Shinoe, Kenji; Takaki, Hiroyuki; Fujisawa, Masami; Hayano, Hitoshi; Muto, Toshiya; Nomura, Masaharu; Kamiya, Yukihide; Koseki, Tadashi; Amemiya, Yoshiyuki; Aoki, Nobutada; Nakayama, Koichi

    2004-01-01

    We have developed a beam profile monitor using two Fresnel zone plates (FZPs) at the KEK-ATF (Accelerator Test Facility) damping ring to measure small electron-beam sizes for low-emittance synchrotron radiation sources. The monitor has a structure of an X-ray microscope, where two FZPs constitute an X-ray imaging optics. In the monitor system, the synchrotron radiation from the electron beam at the bending magnet is monochromatized to 3.235-keV X-rays by a crystal monochromator and the transverse electron-beam image is twenty-times magnified by the two FZPs and detected on an X-ray CCD camera. This monitor has the following advantages: (1) high spatial resolution, (2) non-destructive measurement, (3) real-time monitoring, and (4) direct electron-beam imaging. With the beam profile monitor, we have succeeded in obtaining a clear electron-beam image and measuring the extremely small beam size less than 10 μm. The measured magnification of the imaging optics was in good agreement with the design value

  19. Two case studies of post-seismic regime in the Vrancea region

    International Nuclear Information System (INIS)

    Ciucu, I.; Fulga, C.

    2008-01-01

    The main geophysical conceptions regarding the tectonic seismicity of the Vrancea region are presented, with emphasis on great historical earthquakes as recorded by the Romanian Earthquake Catalogue. Their geographical and in-depth distribution is also presented, as well as their main characteristics. The post-seismic regime of two main events in Vrancea (August 1986 and May 1990) is analyzed, and Omori exponents are derived for the aftershocks distribution. One exponent agrees qualitatively with the usual range of exponents (0.8 with respect to 1), while the other exponent seems to be outside this range (0.3), possibly due to an imperfect definition of the genuine aftershocks. (authors)

  20. The study of the maintenance for a cryogenics pilot plant in nuclear regime

    International Nuclear Information System (INIS)

    Anghel, Vasile

    2002-01-01

    The Cryogenic Pilot Plant, CPP, has as goal the extraction of tritium from heavy water at the CANDU Reactors in Cernavoda. Its operation allows a continuos nuclear regime. CPP consists in several modules, each of them implying static and dynamical complex equipment in which fluids circulate at cryogenic temperatures. From these reasons it results that the CPP maintenance is essential. The relational structure regarding the integrated maintenance systems in the whole ICSI's activity is presented in the frame of management decision system and contains a procedural program of maintenance (PPM). PPM includes adoption strategy for maintenance activity in the conditions required by the Manuals worked out in compliance with QA of ICSI and specific regulations of operation in nuclear regime. An explanation based on a thorough analysis is given for the strategy of maintenance, the structure of modules and the use of informatics subsystems. The structure of PPM strategy has a flowchart implying: - Reorganization, Scientific background, and Operative Maintenance strategy (inside/outside strategy) as well as PPM stage realization and specifications for maintenance assurance (manuals, cards and subsystems). Also, provided in the maintenance strategy are the PPM preparatory and proper stage conceptions

  1. DISASTER REGIME CHARACTER: A STUDY OF DISASTER RISK REDUCTION AT MERAPI VOLCANO ERUPTION IN SLEMAN DISTRICT

    Directory of Open Access Journals (Sweden)

    Nurlia Dian Paramita

    2012-08-01

    Full Text Available This research analyses how the existence of the character occurred in one of disaster management phases which is an emergency response. In addition, it aims to discuss and see the relationship between authority institutions in the disaster management which are Kesbanglinmas & PB Kab. Sleman, Muhammadiyah Disaster Management Centre (MDMC, and Merapi Circle Information Network (JALIN MERAPI. This research uses qualitative method. The data about the policy and survivor handling are got through interviews with representatives from Pakem, Turi, and Cangkringan. They are head of sub districts, head of villages, and head of country-sides. The findings of this research show that the disaster regime character is fatalist-individualist and the authority relation is substitution (acts as a substitute. Therefore, humanity-based point of view is important to see the risk. It will empower the capacity of government institutions. The last, involving civil society (CSO is also significant to streamline the role of disaster management regime guide. Therefore, the synergy between government and CSO will easily be achieved to implement Community-Based Disaster Risk Management (CBDRM. CSO is the government’s partner to reduce disaster.

  2. Illumination uniformity issue explored via two-stage solar concentrator system based on Fresnel lens and compound flat concentrator

    International Nuclear Information System (INIS)

    Yeh, Naichia

    2016-01-01

    This paper illustrates details about the solar radiation distribution on the target of a two-stage solar concentrator that combines the Fresnel lens (FL) and the compound flat concentrator (CFC). The paper starts with a review of some FL development milestones such as the two-stage systems and the comparisons of flat vs. curved lenses in addition to the most noteworthy FL-based solar energy application, concentration photovoltaic (CPV). Through the review of the FL based CPV and two-stage concentrators, this study leads to the development of an algorithm to explore the spectrum distribution insight on the receiver of a two-stage (FL plus CFC) solar concentration system. It established the potential for using a correctly positioned 2nd stage reflector of right dimension to selectively redirect the desired spectrum on the target area so as to enhance the concentration flux intensity and uniformity at the same time. The study also helped to chart out the approximate locations of certain spectrum segments on the FL's target area, which is useful for exploring the spectrum control mechanism via the Fresnel lenses. - Highlights: • Map out the approximate locations of spectrum segments on FL's focal area. • Use the 2nd stage reflector to selectively reflect the desired spectrum on target. • Explore the spectrum distribution insight on FL solar concentrators' target area.

  3. Picosecond Soft-X-ray studies of Dense Plasma Regimes Progress Report (April 1, 2006 - March 31, 2007)

    International Nuclear Information System (INIS)

    Rocca, Jorge; Marconi, Mario; Shlyaptsev, Vyacheslav; Dunn, James; Moon, Stephen; Nilsen, Joseph

    2007-01-01

    The goal of this project is to investigate and characterize high-density converging plasma configurations using new soft x-ray laser based interferometric techniques. The results are used to verify and validate multi-dimensional hydrodynamic codes in plasma regimes which densities and size exceed those that can be probed with optical laser beams. The dynamics of converging plasmas created by laser irradiation of half-hohlraum cylindrical cavities targets was probed using a compact 46.9 nm soft x-ray laser. The results were used for comparison with extensive simulations conducted with the multi-dimensional hydrodynamic code HYDRA. As part of this study we have also investigated plasma regimes in which the index of refraction of the plasmas can not be defined solely based on the contribution of free electron, as is usually assumed for multiply ionized plasmas. Our results demonstrate the existence of plasma regimes in which the contribution of bound electrons from ions dominates the refractive index at soft x-ray wavelengths. We are also working in extending plasma interferometry to the sub 10 nm wavelength range. In the process we are advancing soft x-ray laser plasma diagnostics techniques to allow the measurement of large-scale, high-density plasmas with picosecond temporal resolution and micrometer spatial resolution, laying the foundations for future advanced diagnostics at high energy density DOE facilities. Dense plasma diagnostics, soft x-ray laser interferometry, converging plasmas

  4. Experimental Investigation on the Feasibility of Using a Fresnel Lens as a Solar-Energy Collection System for Enhancing On-Orbit Power Generation Performance

    Directory of Open Access Journals (Sweden)

    Tae-Yong Park

    2017-01-01

    Full Text Available Cube satellites have a limitation for generating power because of their cubic structure and extremely small size. In addition, the incidence angle between the sun and the solar panels continuously varies owing to the revolution and rotation of the satellite according to the attitude control strategy. This angle is an important parameter for determining the power generation performance of the cube satellite. In this study, we performed an experimental feasibility study that uses a Fresnel lens as a solar-energy collection system for cube satellite applications, so that the power generation efficiency can be enhanced under the worst incidence angle condition between the sun and solar panels by concentrating and redirecting solar energy onto the solar panels with a commercial Fresnel lens. To verify the effectiveness of the proposed system, we conducted a power-measurement test using a solar simulator and Fresnel lenses at various angles to the light source. In addition, we predicted the on-orbit power-generation enhancement achieved by employing the solar-energy collection system with various attitude control strategies.

  5. Monte Carlo studies of diamagnetism and charge density wave order in the cuprate pseudogap regime

    Science.gov (United States)

    Hayward Sierens, Lauren; Achkar, Andrew; Hawthorn, David; Melko, Roger; Sachdev, Subir

    2015-03-01

    The pseudogap regime of the hole-doped cuprate superconductors is often characterized experimentally in terms of a substantial diamagnetic response and, from another point of view, in terms of strong charge density wave (CDW) order. We introduce a dimensionless ratio, R, that incorporates both diamagnetic susceptibility and the correlation length of CDW order, and therefore reconciles these two fundamental characteristics of the pseudogap. We perform Monte Carlo simulations on a classical model that considers angular fluctuations of a six-dimensional order parameter, and compare our Monte Carlo results for R with existing data from torque magnetometry and x-ray scattering experiments on YBa2Cu3O6+x. We achieve qualitative agreement, and also propose future experiments to further investigate the behaviour of this dimensionless ratio.

  6. Comparison of Fresnel zone plates and uniformly redundant arrays

    International Nuclear Information System (INIS)

    Fenimore, E.E.; Cannon, T.M.; Miller, E.L.

    1978-01-01

    Several imaging systems in laser fusion, e-beam fusion, and astronomy employ a Fresnel zone plate (FZP) as a coded aperture. The recent development of uniformly redundant arrays (URAs) promises several improvements in these systems. The first advantage of the URA is the fact that its modulation transfer function (MTF) is the same as the MTF of a single pinhole, whereas the MTF of an FZP is an erratic function including some small values. This means that if inverse filtering is used, the URA will be less susceptible to noise. If a correlation analysis is used, the FZP will produce artifacts whereas the URA has no artifacts (assuming planar sources). Both the FZP and URA originated from functions which had flat MTFs. However, practical considerations in the implementation of the FZP detracted from its good characteristics whereas the URA was only mildly affected. The second advantage of the URA is that it better utilizes the available detector area. With the FZP, the aperture should be smaller than the detector in order to maintain the full angular resolution corresponding to the thinnest zone. The cyclic nature of the URA allows one to mosaic it in such a way that the entire detector area collects photons from all of the sources within the field of view while maintaining the full angular resolution. If the FZP is as large (or larger) than the detector, all parts of the source will not be resolved with the same resolution. The FZP does have some advantages, in particular its radial symmetry eases the alignment problem; it has a convenient optical decoding method; and higher diffraction order reconstruction might provide better spatial resolution

  7. Accuracy concerns in digital speckle photography combined with Fresnel digital holographic interferometry

    Science.gov (United States)

    Zhao, Yuchen; Zemmamouche, Redouane; Vandenrijt, Jean-François; Georges, Marc P.

    2018-05-01

    A combination of digital holographic interferometry (DHI) and digital speckle photography (DSP) allows in-plane and out-of-plane displacement measurement between two states of an object. The former can be determined by correlating the two speckle patterns whereas the latter is given by the phase difference obtained from DHI. We show that the amplitude of numerically reconstructed object wavefront obtained from Fresnel in-line digital holography (DH), in combination with phase shifting techniques, can be used as speckle patterns in DSP. The accuracy of in-plane measurement is improved after correcting the phase errors induced by reference wave during reconstruction process. Furthermore, unlike conventional imaging system, Fresnel DH offers the possibility to resize the pixel size of speckle patterns situated on the reconstruction plane under the same optical configuration simply by zero-padding the hologram. The flexibility of speckle size adjustment in Fresnel DH ensures the accuracy of estimation result using DSP.

  8. Diffuse correlation tomography in the transport regime: A theoretical study of the sensitivity to Brownian motion

    Science.gov (United States)

    Tricoli, Ugo; Macdonald, Callum M.; Durduran, Turgut; Da Silva, Anabela; Markel, Vadim A.

    2018-02-01

    Diffuse correlation tomography (DCT) uses the electric-field temporal autocorrelation function to measure the mean-square displacement of light-scattering particles in a turbid medium over a given exposure time. The movement of blood particles is here estimated through a Brownian-motion-like model in contrast to ordered motion as in blood flow. The sensitivity kernel relating the measurable field correlation function to the mean-square displacement of the particles can be derived by applying a perturbative analysis to the correlation transport equation (CTE). We derive an analytical expression for the CTE sensitivity kernel in terms of the Green's function of the radiative transport equation, which describes the propagation of the intensity. We then evaluate the kernel numerically. The simulations demonstrate that, in the transport regime, the sensitivity kernel provides sharper spatial information about the medium as compared with the correlation diffusion approximation. Also, the use of the CTE allows one to explore some additional degrees of freedom in the data such as the collimation direction of sources and detectors. Our results can be used to improve the spatial resolution of DCT, in particular, with applications to blood flow imaging in regions where the Brownian motion is dominant.

  9. A STUDY OF SOLID STATE LASER PASSIVE OPTICAL Q-SWITCHING OPERATION REGIME (Part 1

    Directory of Open Access Journals (Sweden)

    Ion LĂNCRĂNJAN

    2009-09-01

    Full Text Available This paper is the first of a four series treating, theoretically with experimental comparison, the issue of solid state laser passive optical Q-switching regime. In this first paper the technique of solid state lasers passive optical Q-switching is numerically investigated considering the case of longitudinally and transversally uniform photon, population inversion and absorption centres densities. The coupled differential equations defining photon, population inversion and absorption centres densities are numerically solved being the basis of passively optical Q-switched laser functional simulation. The numerical simulations are performed using the several software packages, mostly SCILAB programs. The developed SCILAB programs can be used for a large range of saturable absorption centre and active media parameters, mainly the initial (low signal optical transmittance of the passive optical Q-switch. The developed FORTRAN and SCILAB programs can be applied for passively Q-switched solid state lasers of several types emitting at several NIR wavelengths, in domain 1 ÷ 2 μm. For validating the numerical simulation results are compared with The results of the numerical simulation are compared with experimentally obtained ones, in the case of a LiF:F2- passively Q-switched Nd:YAG. A good agreement between the two kinds of results is observed.

  10. Study of neoclassical transport in the 1/ν regime for a research fusion reactor

    International Nuclear Information System (INIS)

    Kalyuzhnyj, V.N.; Kasilov, S.V.; Nemov, V.V.

    2005-01-01

    In frame of the concept of a steady-state operated research fusion reactor (RFR) in papers [1-4] the RFR with an increased plasma-wall detachment was proposed with the purpose to enable not only the production but also a long-term confinement of a self-sustained plasma at the existing technology level. In connection with complication of the corresponding magnetic configuration an investigation of the neoclassical transport is desirable for such systems. In the present work neoclassical transport for a magnetic configuration of l=2 torsatron type variant of RFR system with an additional opposite toroidal magnetic field is investigated numerically. A so-called 1/ν transport regime, in which the transport coefficients are increased with reduction of particle collision frequency ν is considered. For calculating of transport coefficients a technique, based on integration along magnetic field lines in a given stellarator magnetic field is used. The magnetic field of helical windings is calculated by Biot-Savart law. The obtained transport coefficients are presented in a standard form containing a factor depending on the magnetic field geometry. From analysis of the received results follows that in respect of the neoclassical transport the proposed magnetic configuration turns out to be closer to configuration of the classical stellarator (with helical winding), than to configuration of the classical torsatron/geliotron. (author)

  11. Stable and simple quantitative phase-contrast imaging by Fresnel biprism

    Science.gov (United States)

    Ebrahimi, Samira; Dashtdar, Masoomeh; Sánchez-Ortiga, Emilio; Martínez-Corral, Manuel; Javidi, Bahram

    2018-03-01

    Digital holographic (DH) microscopy has grown into a powerful nondestructive technique for the real-time study of living cells including dynamic membrane changes and cell fluctuations in nanometer and sub-nanometer scales. The conventional DH microscopy configurations require a separately generated coherent reference wave that results in a low phase stability and a necessity to precisely adjust the intensity ratio between two overlapping beams. In this work, we present a compact, simple, and very stable common-path DH microscope, employing a self-referencing configuration. The microscope is implemented by a diode laser as the source and a Fresnel biprism for splitting and recombining the beams simultaneously. In the overlapping area, linear interference fringes with high contrast are produced. The frequency of the interference pattern could be easily adjusted by displacement of the biprism along the optical axis without a decrease in fringe contrast. To evaluate the validity of the method, the spatial noise and temporal stability of the setup are compared with the common off-axis DH microscope based on a Mach-Zehnder interferometer. It is shown that the proposed technique has low mechanical noise as well as superb temporal stability with sub-nanometer precision without any external vibration isolation. The higher temporal stability improves the capabilities of the microscope for studying micro-object fluctuations, particularly in the case of biological specimens. Experimental results are presented using red blood cells and silica microspheres to demonstrate the system performance.

  12. Comparative study on fast neutrons radiobiological effect on Chinese hamster cells in culture depending on regime of irradiation

    International Nuclear Information System (INIS)

    Elisova, T.V.; Feoktistova, T.P.; Stavrakova, N.M.

    1988-01-01

    Comparative study of regularities of fast neutron radiobiological effect on Chinese hamster cells in culture under pulse and statistic irradiation regimes that was estimated by reproductive death of cells and induced frequency of resistence mutations to 6-tioguanine is carried out. It is stated that with the dose rate increase approximately by 6 orders radiobiological efficiency of fast neutrons decreases. It is suggested that one of the causes of decreasing pulse irradiation efficiency are processes on radiation-chemical level. 9 refs.; 3 figs

  13. Supply regimes in fisheries

    DEFF Research Database (Denmark)

    Nielsen, Max

    2006-01-01

    Supply in fisheries is traditionally known for its backward bending nature, owing to externalities in production. Such a supply regime, however, exist only for pure open access fisheries. Since most fisheries worldwide are neither pure open access, nor optimally managed, rather between the extremes......, the traditional understanding of supply regimes in fisheries needs modification. This paper identifies through a case study of the East Baltic cod fishery supply regimes in fisheries, taking alternative fisheries management schemes and mesh size limitations into account. An age-structured Beverton-Holt based bio......-economic supply model with mesh sizes is developed. It is found that in the presence of realistic management schemes, the supply curves are close to vertical in the relevant range. Also, the supply curve under open access with mesh size limitations is almost vertical in the relevant range, owing to constant...

  14. Color image cryptosystem using Fresnel diffraction and phase modulation in an expanded fractional Fourier transform domain

    Science.gov (United States)

    Chen, Hang; Liu, Zhengjun; Chen, Qi; Blondel, Walter; Varis, Pierre

    2018-05-01

    In this letter, what we believe is a new technique for optical color image encryption by using Fresnel diffraction and a phase modulation in an extended fractional Fourier transform domain is proposed. Different from the RGB component separation based method, the color image is converted into one component by improved Chirikov mapping. The encryption system is addressed with Fresnel diffraction and phase modulation. A pair of lenses is placed into the fractional Fourier transform system for the modulation of beam propagation. The structure parameters of the optical system and parameters in Chirikov mapping serve as extra keys. Some numerical simulations are given to test the validity of the proposed cryptosystem.

  15. Design and fabrication of Si-HDPE hybrid Fresnel lenses for infrared imaging systems.

    Science.gov (United States)

    Manaf, Ahmad Rosli Abdul; Sugiyama, Tsunetoshi; Yan, Jiwang

    2017-01-23

    In this work, novel hybrid Fresnel lenses for infrared (IR) optical applications were designed and fabricated. The Fresnel structures were replicated from an ultraprecision diamond-turned aluminum mold to an extremely thin layer (tens of microns) of high-density polyethylene polymer, which was directly bonded onto a flat single-crystal silicon wafer by press molding without using adhesives. Night mode imaging results showed that the fabricated lenses were able to visualize objects in dark fields with acceptable image quality. The capability of the lenses for thermography imaging was also demonstrated. This research provides a cost-effective method for fabricating ultrathin IR optical components.

  16. Component and prototype panel testing of the mini-dome Fresnel lens photovoltaic concentrator array

    Science.gov (United States)

    Piszczor, Michael F.; Swartz, Clifford K.; O'Neill, Mark J.

    1990-01-01

    The mini-dome Fresnel lens concentrator array, a high-efficiency, lightweight space photovoltaic array concept, is described. The three critical elements of the array concept are the Fresnel lens concentrator, the prismatic cell power cover, and the photovoltaic cell. Prototype concentrator lenses have been fabricated and tested, with optical efficiencies reaching 90 percent. Work is progressing on the design and fabrication of the panel structure. The impact of recent advances in 30 percent-efficient multijunction photovoltaic cells on array performance is also discussed. Near-term performance goals of 300 w/sq m and 100 w/kg are now feasible.

  17. Fresnel Lens Solar Concentrator Design Based on Geometric Optics and Blackbody Radiation Equations

    Science.gov (United States)

    Watson, Michael D.; Jayroe, Robert, Jr.

    1999-01-01

    Fresnel lenses have been used for years as solar concentrators in a variety of applications. Several variables effect the final design of these lenses including: lens diameter, image spot distance from the lens, and bandwidth focused in the image spot. Defining the image spot as the geometrical optics circle of least confusion and applying blackbody radiation equations the spot energy distribution can be determined. These equations are used to design a fresnel lens to produce maximum flux for a given spot size, lens diameter, and image distance. This approach results in significant increases in solar efficiency over traditional single wavelength designs.

  18. Why history matters: Ab initio rederivation of Fresnel equations confirms microscopic theory of refractive index

    Science.gov (United States)

    Starke, R.; Schober, G. A. H.

    2018-03-01

    We provide a systematic theoretical, experimental, and historical critique of the standard derivation of Fresnel's equations, which shows in particular that these well-established equations actually contradict the traditional, macroscopic approach to electrodynamics in media. Subsequently, we give a rederivation of Fresnel's equations which is exclusively based on the microscopic Maxwell equations and hence in accordance with modern first-principles materials physics. In particular, as a main outcome of this analysis being of a more general interest, we propose the most general boundary conditions on electric and magnetic fields which are valid on the microscopic level.

  19. How kinship systems and welfare regimes shape leaving home: A comparative study of the United States, Germany, Taiwan, and China

    Directory of Open Access Journals (Sweden)

    Bernhard Nauck

    2017-04-01

    Full Text Available Objective: This paper aims to explain societal differences in the event of leaving the parental home as part of the transition to adulthood, in the United States, Germany, China, and Taiwan. It proposes bridge hypotheses between societal characteristics such as kinship system and welfare regime and home-leaving behavior, and tests them with nationally representative panel studies. Methods: Four panel studies (NLSY97 for the USA; PAIRFAM for Germany; CFPS for China; TYP for Taiwan were harmonized for similar cohorts, with an age span of 15 to 30 years. Testing was based on age-specific tabulations of household composition and separate discrete-time event history models. Results: The prevalence of home-leaving is highest in the United States, followed by Germany, China, and then Taiwan. Timing is earlier in the United States than in Germany, and earlier in China than in Taiwan. Gender-specific coincidence of home-leaving with entry into higher education, the work force, cohabitation, and marriage can be conclusively related to differences in kinship system and welfare regime, and regional opportunity disparities. Contribution: The empirical results point to significant cultural differences between home-leaving in collectivistic, patrilineal societies (China, Taiwan and individualistic, bilineal societies (USA, Germany. Whereas neolocal housing signifies an important step in the transition to adulthood in the latter societies, continuous intergenerational housing, or even an early return to it, is normatively supported in collectivistic cultures. Differences between the United States and Germany on the one hand, and China and Taiwan on the other, point to variation in welfare regimes and differences in urbanization.

  20. Sparse synthetic aperture with Fresnel elements (S-SAFE) using digital incoherent holograms

    Science.gov (United States)

    Kashter, Yuval; Rivenson, Yair; Stern, Adrian; Rosen, Joseph

    2015-01-01

    Creating a large-scale synthetic aperture makes it possible to break the resolution boundaries dictated by the wave nature of light of common optical systems. However, their implementation is challenging, since the generation of a large size continuous mosaic synthetic aperture composed of many patterns is complicated in terms of both phase matching and time-multiplexing duration. In this study we present an advanced configuration for an incoherent holographic imaging system with super resolution qualities that creates a partial synthetic aperture. The new system, termed sparse synthetic aperture with Fresnel elements (S-SAFE), enables significantly decreasing the number of the recorded elements, and it is free from positional constrains on their location. Additionally, in order to obtain the best image quality we propose an optimal mosaicking structure derived on the basis of physical and numerical considerations, and introduce three reconstruction approaches which are compared and discussed. The super-resolution capabilities of the proposed scheme and its limitations are analyzed, numerically simulated and experimentally demonstrated. PMID:26367947

  1. Extended Huygens-Fresnel principle and optical waves propagation in turbulence: discussion.

    Science.gov (United States)

    Charnotskii, Mikhail

    2015-07-01

    Extended Huygens-Fresnel principle (EHF) currently is the most common technique used in theoretical studies of the optical propagation in turbulence. A recent review paper [J. Opt. Soc. Am. A31, 2038 (2014)JOAOD60740-323210.1364/JOSAA.31.002038] cites several dozens of papers that are exclusively based on the EHF principle. We revisit the foundations of the EHF, and show that it is burdened by very restrictive assumptions that make it valid only under weak scintillation conditions. We compare the EHF to the less-restrictive Markov approximation and show that both theories deliver identical results for the second moment of the field, rendering the EHF essentially worthless. For the fourth moment of the field, the EHF principle is accurate under weak scintillation conditions, but is known to provide erroneous results for strong scintillation conditions. In addition, since the EHF does not obey the energy conservation principle, its results cannot be accurate for scintillations of partially coherent beam waves.

  2. A PROSPECTIVE, OBSERVATIONAL STUDY OF ADVERSE REACTIONS TO DRUG REGIME FOR MULTI-DRUG RESISTANT PULMONARY TUBERCULOSIS IN CENTRAL INDIA.

    Directory of Open Access Journals (Sweden)

    Dr. Rohan C. Hire

    2014-09-01

    Full Text Available Abstract Objective: 1 To assess the adverse drug reactions of second line anti-tubercular drugs used to treat Multi-drug resistant Tuberculosis (MDR TB in central India on the basis of causality, severity and avoidability scales. 2 To study the relationship of type of MDR TB (primary or secondary and presence of diabetes mellitus (DM with mean smear conversion time. Material and Methods: A prospective, observational study was carried out on diagnosed multidrug resistant tuberculosis patients enrolled for DOTS‑Plus regimen at TB and Chest Disease Department from January to December 2012. They were followed for 9 months thereafter and encountered adverse drug reactions (ADRs were noted along with the time of sputum conversion. The data were analysed by Chi-square or Fisher’s exact test and unpaired student’s‘t’ test. Results: Total 64 ADRs were reported in 55 patients out of total 110 patients (n = 110. As per the Naranjo causality assessment of ADRs, 7 patients had “definite” causal relation, 45 had “probable” causal relation and 3 had “possible” causal relation with drugs of DOTS Plus regime. As per the Hartwig’s severity assessment scale, there were total 7 ADRs in Level 1, 6 in Level 2, 33 in Level 3 and 9 in Level 4. Hallas avoidability assessment scale divided the ADRs as 3 being “Definitely avoidable”, 26 “Possibly avoidable”, 23 “Not avoidable” and 3 “unevaluable”. . Mean sputum smear conversion time is significantly higher in patients with secondary type than that of primary type of MDR TB (p = 0.0001 and in patients with DM than those without DM (p <0.0001. Conclusion: ADRs were common in patients of MDR TB on DOTs-Plus drug regime. It was due to lack of availability of safer and equally potent drugs in DOTs-Plus drug regime compared to DOTS regime in non-resistant TB. The frequency and severity of ADRs can be reduced by strict vigilance about known and unknown ADRs, monitoring their laboratory and

  3. Bi facial silicon solar cell study in modelling in frequency dynamic regime under multispectral illumination: Recombination parameters determination methods

    International Nuclear Information System (INIS)

    ZERBO Issa

    2010-01-01

    A bibliographic study on the techniques of characterization of silicon solar cell, diodes, massifs and silicon wafer are presented. The influence of the modulation frequency and recombination in volume and in surface phenomena of on the profiles of carriers' densities, photocurrent and photovoltage has been put in evidence. The study of surface recombination velocities permitted to show that the bi facial silicon solar cell of Back Surface Field type behaves like an ohmic contacts solar cell for modulation frequencies above 40 khz. pplicability in frequency dynamic regime in the frequency range [0 - 40 khz] of three techniques of steady state recombination parameters determination is shown. A technique of diffusion length determination, in the range of (200 Hz - 40 khz] is proposed. It rests on the measurement of the short circuit current phase that is compared with the theoretical curve of short circuit current phase. The intersection of the experimental short circuit current phase and the theoretical curve of short circuit current phase permits to get the minority carriers effective diffusion length. An equivalent electric model of a solar cell in frequency dynamic regime is proposed. A study in modelling of the bi facial solar cell shunt resistance and space charge zone capacity is led from a determination method of these parameters proposed in steady state. (Author [fr

  4. Long-Term Downstream Effects of a Dam on a Lowland River Flow Regime: Case Study of the Upper Narew

    Directory of Open Access Journals (Sweden)

    Paweł Marcinkowski

    2017-10-01

    Full Text Available Most European riverine ecosystems suffer from the negative influence of impoundments on flow regime. Downstream effects of dams lead to a number of environmental and socioeconomic risks and, therefore, should be thoroughly examined in specific contexts. Our study aims to quantify the downstream effects of the Siemianówka Reservoir (Upper Narew, Poland, using statistical analysis of key elements of the river’s flow regime, such as the flow duration and recurrence of floods and droughts. In a comparative study on control catchments not influenced by impoundments (the Supraśl and Narewka Rivers, we revealed the following downstream effects of the analyzed dam: significant shortening of spring floods, reduction of the duration and depth of summer droughts, decrease of the maximum discharge, and homogenization of the discharge hydrographs. Although we determined a significant decrease in the duration of summer floods in the “before” and “after” dam function periods, we showed that this issue is regional, climate-related, and replicated in control catchments, rather than an evident downstream effect of the dam. We conclude that significant hydrological downstream effects of the Siemianówka dam–reservoir system could have been the main driver inducing the deterioration of the anastomosing stretch of the Narew River downstream of the dam.

  5. Final report for Fundamental study of long-short interfacial wave interactions with application for flow regime development

    CERN Document Server

    McCready, M

    2000-01-01

    The long waves that cause slugs almost always form more slowly than short waves, and linear stability always predicts that the growth rate for long waves is much less than that for short waves. However, at many conditions above neutral stability, long waves dominate the wave field. Three different studies were undertaken as part of the funded work: (1) linear interaction for unsteady flows; (2) wave evolution in oil-water channel flows; (3) retrograde stability and subcritical bifurcations. The oil-water system was used as a surrogate for gas-liquid systems because the gas phase is usually turbulent, and this complication is thus avoided although the phenomena involved are similar. The following overall conclusions about flow regime development were reached: (a) Oscillations in pressure and flow rate, due to interfacial waves or a malfunctioning pump, can cause significant growth rate changes in short waves within narrow FR-equency ranges, but probably do not have a large effect on long waves and thus regime ...

  6. Development of multilayer Fresnel lens (zone plate) for formation of focused neutron beam

    International Nuclear Information System (INIS)

    Tamura, Shigeharu

    2008-01-01

    Multilayer Fresnel zone plates (FZPs) for the neutron beamline have been designed and fabricated. Firstly, materials for the FZP were examined: layer materials, wire substrate, etc. Secondly, FZPs were designed and three kinds of FZPs were fabricated: two Cu/Al-FZPs and a Ni(Cr)/Al-FZP. (author)

  7. High convergence efficiency design of flat Fresnel lens with large aperture

    Science.gov (United States)

    Ke, Jieyao; Zhao, Changming; Guan, Zhe

    2018-01-01

    This paper designed a circle-shaped Fresnel lens with large aperture as part of the solar pumped laser design project. The Fresnel lens designed in this paper simulate in size 1000mm×1000mm, focus length 1200mm and polymethyl methacrylate (PMMA) material in order to conduct high convergence efficiency. In the light of design requirement of concentric ring with same width of 0.3mm, this paper proposed an optimized Fresnel lens design based on previous sphere design and conduct light tracing simulation in Matlab. This paper also analyzed the effect of light spot size, light intensity distribution, optical efficiency under four conditions, monochromatic parallel light, parallel spectrum light, divergent monochromatic light and sunlight. Design by 550nm wavelength and under the condition of Fresnel reflection, the results indicated that the designed lens could convergent sunlight in diffraction limit of 11.8mm with a 78.7% optical efficiency, better than the sphere cutting design results of 30.4%.

  8. A fast point-cloud computing method based on spatial symmetry of Fresnel field

    Science.gov (United States)

    Wang, Xiangxiang; Zhang, Kai; Shen, Chuan; Zhu, Wenliang; Wei, Sui

    2017-10-01

    Aiming at the great challenge for Computer Generated Hologram (CGH) duo to the production of high spatial-bandwidth product (SBP) is required in the real-time holographic video display systems. The paper is based on point-cloud method and it takes advantage of the propagating reversibility of Fresnel diffraction in the propagating direction and the fringe pattern of a point source, known as Gabor zone plate has spatial symmetry, so it can be used as a basis for fast calculation of diffraction field in CGH. A fast Fresnel CGH method based on the novel look-up table (N-LUT) method is proposed, the principle fringe patterns (PFPs) at the virtual plane is pre-calculated by the acceleration algorithm and be stored. Secondly, the Fresnel diffraction fringe pattern at dummy plane can be obtained. Finally, the Fresnel propagation from dummy plan to hologram plane. The simulation experiments and optical experiments based on Liquid Crystal On Silicon (LCOS) is setup to demonstrate the validity of the proposed method under the premise of ensuring the quality of 3D reconstruction the method proposed in the paper can be applied to shorten the computational time and improve computational efficiency.

  9. Accurate reconstruction in digital holographic microscopy using Fresnel dual-tree complex wavelet transform

    Science.gov (United States)

    Zhang, Xiaolei; Zhang, Xiangchao; Yuan, He; Zhang, Hao; Xu, Min

    2018-02-01

    Digital holography is a promising measurement method in the fields of bio-medicine and micro-electronics. But the captured images of digital holography are severely polluted by the speckle noise because of optical scattering and diffraction. Via analyzing the properties of Fresnel diffraction and the topographies of micro-structures, a novel reconstruction method based on the dual-tree complex wavelet transform (DT-CWT) is proposed. This algorithm is shiftinvariant and capable of obtaining sparse representations for the diffracted signals of salient features, thus it is well suited for multiresolution processing of the interferometric holograms of directional morphologies. An explicit representation of orthogonal Fresnel DT-CWT bases and a specific filtering method are developed. This method can effectively remove the speckle noise without destroying the salient features. Finally, the proposed reconstruction method is compared with the conventional Fresnel diffraction integration and Fresnel wavelet transform with compressive sensing methods to validate its remarkable superiority on the aspects of topography reconstruction and speckle removal.

  10. LED Uniform Illumination Using Double Linear Fresnel Lenses for Energy Saving

    Directory of Open Access Journals (Sweden)

    Ngoc Hai Vu

    2017-12-01

    Full Text Available We present a linear Fresnel lens design for light-emitting diode (LED uniform illumination applications. The LED source is an array of LEDs. An array of collimating lens is applied to collimate output from the LED array. Two linear Fresnel lenses are used to redistribute the collimated beam along two dimensions in the illumination area. Collimating lens and linear Fresnel lens surfaces are calculated by geometrical optics and nonimaging optics. The collimated beam output from the collimating lens array is divided into many fragments. Each fragment is refracted by a segment of Fresnel lens and distributed over the illumination area, so that the total beam can be distributed to the illumination target uniformly. The simulation results show that this design has a compact structure, high optical efficiency of 82% and good uniformity of 76.9%. Some consideration of the energy savings and optical performance are discussed by comparison with other typical light sources. The results show that our proposed LED lighting system can reduce energy consumption five-times in comparison to using a conventional fluorescent lamp. Our research is a strong candidate for low cost, energy savings for indoor and outdoor lighting applications.

  11. Design of a segmented nonimaging Fresnel dome for nontracking solar collection

    Science.gov (United States)

    Viera-González, Perla M.; Sánchez-Guerrero, Guillermo E.; Martínez-Guerra, Edgar; Ceballos-Herrera, Daniel E.

    2017-07-01

    The efficiency of sunlight collection systems is related to the optical element used as a collector. On this subject, the design of a nontracking solar collector that consists of a segmented nonimaging Fresnel dome is presented. It is formed by the conjunction of different zones for solar collection, where each one is a nonimaging Fresnel lens that collects a specific angular range (θ) of sunlight received in the northeast of Mexico, but the methodology presented can be easily extended to other geographic locations. The final design is a semistationary segmented collector with a 100-cm diameter and 50-cm focal length that needs a 180-deg rotation over the XY-plane in each equinox. The numerical simulations show that the nontracking segmented collector has a combined acceptance semiangle of θ=±105 deg with an average efficiency of over 67% from 9:00 to 18:00 h. The spatial and angular distributions of the sunlight collected are also included. This design has a collection area equal to that of a single nonimaging Fresnel lens with an acceptance semiangle of θ=±45 deg. These results are reproducible and provide valuable data for designing nontracking solar collectors based on nonimaging Fresnel lens.

  12. Optical sectioning using a digital Fresnel incoherent-holography-based confocal imaging system

    Science.gov (United States)

    Kelner, Roy; Katz, Barak; Rosen, Joseph

    2015-01-01

    We propose a new type of confocal microscope using Fresnel incoherent correlation holography (FINCH). Presented here is a confocal configuration of FINCH using a phase pinhole and point illumination that is able to suppress out-of-focus information from the recorded hologram and hence combine the super-resolution capabilities of FINCH with the sectioning capabilities of confocal microscopy. PMID:26413560

  13. Optical sectioning using a digital Fresnel incoherent-holography-based confocal imaging system

    OpenAIRE

    Kelner, Roy; Katz, Barak; Rosen, Joseph

    2014-01-01

    We propose a new type of confocal microscope using Fresnel incoherent correlation holography (FINCH). Presented here is a confocal configuration of FINCH using a phase pinhole and point illumination that is able to suppress out-of-focus information from the recorded hologram and hence combine the super-resolution capabilities of FINCH with the sectioning capabilities of confocal microscopy.

  14. 24-GHz LTCC Fractal Antenna Array SoP With Integrated Fresnel Lens

    KAUST Repository

    Ghaffar, Farhan A.; Khalid, Muhammad Umair; Salama, Khaled N.; Shamim, Atif

    2012-01-01

    A novel 24-GHz mixed low-temperature co-fired ceramic (LTCC) tape based system-on-package (SoP) is presented, which incorporates a fractal antenna array with an integrated grooved Fresnel lens. The four-element fractal array employs a relatively low

  15. Huygens-Feynman-Fresnel principle as the basis of applied optics.

    Science.gov (United States)

    Gitin, Andrey V

    2013-11-01

    The main relationships of wave optics are derived from a combination of the Huygens-Fresnel principle and the Feynman integral over all paths. The stationary-phase approximation of the wave relations gives the correspondent relations from the point of view of geometrical optics.

  16. Fresnel Lenses fabricated by femtosecond laser micromachining on Polymer 1D Photonic Crystal

    Directory of Open Access Journals (Sweden)

    Guduru Surya S.K.

    2013-11-01

    Full Text Available We report the fabrication of micro Fresnel lenses by femtosecond laser surface ablation on polymer 1D photonic crystals. This device is designed to focus the transmitted wavelength of the photonic crystal and filter the wavelengths corresponding to the photonic band gap region. Integration of such devices in a wavelength selective light harvesting and filtering microchip can be achieved.

  17. Manipulation and analysis of atomic and molecular beams using transmission gratings and Fresnel zone plates

    Energy Technology Data Exchange (ETDEWEB)

    Grisenti, R.E.

    2000-06-01

    In this thesis experimental results on the diffraction of rare gas atoms (He, Ne, Ar, Kr) and molecular (D{sub 2}) beams by a 100 nm period transmission grating and on the focusing of a helium atom beam through a Fresnel zone plate have been reported. (orig.)

  18. A concentrator system for BI-CPVT with static linear Fresnel lenses

    NARCIS (Netherlands)

    Swinkels, G.L.A.M.; Sonneveld, P.J.; Tuijl, van B.A.J.; Janssen, H.J.J.; Zwart, de H.F.

    2011-01-01

    A greenhouse with Fresnel lenses in the south facing roof and a receiver for concentrated Photovoltaic with water cooling (CPVT system) will result in electrical and thermal energy output from the solar energy excess entering a greenhouse. The PV system converts about half of the direct radiation

  19. The study of the hydrological regime extreme effects of the Caspian Sea during the XX-XXI centuries

    Science.gov (United States)

    Yaitskaya, Natalia

    2016-04-01

    The Caspian Sea - the unique largest enclosed inland body of water on Earth. Significant periodic sea level fluctuations are a typical feature of the sea. In the XIX-XX centuries a number of comprehensive studies of the Caspian Sea was carried out. The results are published in the papers, monographs and climatic atlases. But a number of fundamental questions about the features of the hydrological regime of the Caspian Sea is still open: 1. How does the water circulation change during the level variations? 2. What is the effect of heterogeneity of evaporation from the water surface on the formation of the flow field in the conditions of long-term level changes? 3. How does the water salinity regime change depending on the sea level position, water circulation, river flow and different climatic influences? 4. What is the effect of extreme events (multi-hazards) (ice, storms, destruction of the coasts) on coastal infrastructure? In 2016, the project aims to study hydrological regime extreme effects of the Caspian Sea was supported by the Russian Foundation for Basic Research. Within this project all of the above problems will be solved. Geographic information system "Caspian Sea" for the storage and data processing, including a database of primary oceanographic information for the period of instrumental observations (1897-2013), cartographic database (1921-2011) and tools for multidimensional analysis of spatio-temporal information is the basis of the study. The scheme of interconnected hydrodynamic models (Caspian Sea MODel - Ocean Model - Wind wave model) was developed. The important factors are taken into account in the structure of the models: long-term and seasonal dynamics of the sea waves parameters, new long-term values of evaporation from the shallow waters areas of the Caspian Sea, water circulation. Schemes of general seasonal circulation of the Caspian Sea and the Northern Caspian at different positions of the sea level in XX-XXI centuries using

  20. Modeling thermal structure, ice cover regime and sensitivity to climate change of two regulated lakes - a Norwegian case study

    Science.gov (United States)

    Gebre, Solomon; Boissy, Thibault; Alfredsen, Knut

    2013-04-01

    A great number of river and lakes in Norway and the Nordic region at large are regulated for water management such as hydropower production. Such regulations have the potential to alter the thermal and hydrological regimes in the lakes and rivers downstream impacting on river environment and ecology. Anticipated changes as a result of climate change in meteorological forcing data such as air temperature and precipitation cause changes in the water balance, water temperature and ice cover duration in the reservoirs. This may necessitate changes in operational rules as part of an adaptation strategy for the future. In this study, a one dimensional (1D) lake thermodynamic and ice cover model (MyLake) has been modified to take into account the effect of dynamic outflows in reservoirs and applied to two small but relatively deep regulated lakes (reservoirs) in Norway (Follsjøen and Tesse). The objective was to assess climate change impacts on the seasonal thermal characteristics, the withdrawal temperatures, and the reservoir ice cover dynamics with current operational regimes. The model solves the vertical energy balance on a daily time-step driven by meteorological and hydrological forcings: 2m air temperature, precipitation, 2m relative humidity, 10m wind speed, cloud cover, air pressure, solar insolation, inflow volume, inflow temperature and reservoir outflows. Model calibration with multi-seasonal data of temperature profiles showed that the model performed well in simulating the vertical water temperature profiles for the two study reservoirs. The withdrawal temperatures were also simulated reasonably well. The comparison between observed and simulated lake ice phenology (which were available only for one of the reservoirs - Tesse) was also reasonable taking into account the uncertainty in the observational data. After model testing and calibration, the model was then used to simulate expected changes in the future (2080s) due to climate change by considering

  1. Theoretical and Experimental Study of the Friction Behavior of Halogen-Free Ionic Liquids in Elastohydrodynamic Regime

    Directory of Open Access Journals (Sweden)

    Karthik Janardhanan

    2016-05-01

    Full Text Available Ionic Liquids have emerged as effective lubricants and additives to lubricants, in the last decade. Halogen-free ionic liquids have recently been considered as more environmentally stable than their halogenated counterparts, which tend to form highly toxic and corrosive acids when exposed to moisture. Most of the studies using ionic liquids as lubricants or additives of lubricants have been done experimentally. Due to the complex nature of the lubrication mechanism of these ordered fluids, the development of a theoretical model that predicts the ionic liquid lubrication ability is currently one of the biggest challenges in tribology. In this study, a suitable and existing friction model to describe lubricating ability of ionic liquids in the elastohydrodynamic lubrication regime is identified and compared to experimental results. Two phosphonium-based, halogen-free ionic liquids are studied as additives to a Polyalphaolefin base oil in steel–steel contacts using a ball-on-flat reciprocating tribometer. Experimental conditions (speed, load and roughness are selected to ensure that operations are carried out in the elastohydrodynamic regime. Wear volume was also calculated for tests at high speed. A good agreement was found between the model and the experimental results when [THTDP][Phos] was used as an additive to the base oil, but some divergence was noticed when [THTDP][DCN] was added, particularly at the highest speed studied. A significant decrease in the steel disks wear volume is observed when 2.5 wt. % of the two ionic liquids were added to the base lubricant.

  2. Numerical Study on Bubble Dynamics and Two-Phase Frictional Pressure Drop of Slug Flow Regime in Adiabatic T-junction Square Microchannel

    Directory of Open Access Journals (Sweden)

    K. Kishor

    2017-10-01

    Full Text Available In this study, bubble dynamics and frictional pressure drop associated with gas liquid two-phase slug flow regime in adiabatic T-junction square microchannel has been investigated using CFD. A comprehensive study on the mechanism of bubble formation via squeezing and shearing regime is performed. The randomness and recirculation profiles observed in the squeezing regime are significantly higher as compared to the shearing regime during formation of the slug. Further, effects of increasing gas velocity on bubble length are obtained at fixed liquid velocities and simulated data displayed good agreement with available correlations in literature. The frictional pressure drop for slug flow regime from simulations are also obtained and evaluated against existing separated flow models. A regression correlation has also been developed by modifying C-parameter using separated flow model, which improves the prediction of two-phase frictional pressure drop data within slug flow region, with mean absolute error of 10 %. The influences of fluid properties such as liquid viscosity and surface tension on the two-phase frictional pressure drop are also investigated and compared with developed correlation. The higher liquid viscosity and lower surface tension value resulted in bubble formation via shearing regime.

  3. Faithful reconstruction of digital holograms captured by FINCH using a Hamming window function in the Fresnel propagation.

    Science.gov (United States)

    Siegel, Nisan; Rosen, Joseph; Brooker, Gary

    2013-10-01

    Recent advances in Fresnel incoherent correlation holography (FINCH) increase the signal-to-noise ratio in hologram recording by interference of images from two diffractive lenses with focal lengths close to the image plane. Holograms requiring short reconstruction distances are created that reconstruct poorly with existing Fresnel propagation methods. Here we show a dramatic improvement in reconstructed fluorescent images when a 2D Hamming window function substituted for the disk window typically used to bound the impulse response in the Fresnel propagation. Greatly improved image contrast and quality are shown for simulated and experimentally determined FINCH holograms using a 2D Hamming window without significant loss in lateral or axial resolution.

  4. The comparison of two analgesic regimes after ambulatory surgery: an observational study

    NARCIS (Netherlands)

    Worp, F. van der; Stapel, J.T.; Lako, S.J.; Hendriks, J.C.M.; Vissers, K.C.P.; Steegers, M.A.H.

    2014-01-01

    INTRODUCTION: Over the past 15 years, the number of ambulatory surgical procedures worldwide has increased continuously. Studies show that 30% to 40% of the patients experience moderate-to-severe pain in the first 48 hours. The objective of this observational study is to compare the percentage of

  5. Use of stable isotopes in developing countries: safe markers for nutrition regime study

    International Nuclear Information System (INIS)

    Klein, P.D.; Klein, E.R.

    1987-01-01

    Possible use of stable radioisotopes in studies on nutrition and medicine problems that may be used in investigations of babies, children, pregnant women is shown. Attention is paid to behaviour of limited number of elements: hydrogen, carbon, nitrogen, oxygen. The IAEA plans implementation of a new coordinated research program on use of stable isotopes for studying nutrition problems and related diseases. The program emphasis will be placed on protein metabolism measurements and estimation of energy consumption in control population groups in developing countries

  6. Dissociation Pathways of Benzylpyridinium "Thermometer" Ions Depend on the Activation Regime: An IRMPD Spectroscopy Study

    NARCIS (Netherlands)

    Morsa, D.; Gabelica, V.; Rosu, F.; Oomens, J.; De Pauw, E.

    2014-01-01

    The dissociation of benzylpyridinium "thermometer" ions is widely used to calibrate the internal energy of ions produced in mass spectrometry. The fragmentation mechanism is usually believed to yield a benzylium cation, although recent studies suggest the possibility of a rearrangement leading to

  7. Heat transfer in the spin-boson model: a comparative study in the incoherent tunneling regime.

    Science.gov (United States)

    Segal, Dvira

    2014-07-01

    We study the transfer of heat in the nonequilibrium spin-boson model with an Ohmic dissipation. In the nonadiabatic limit we derive a formula for the thermal conductance based on a rate equation formalism at the level of the noninteracting blip approximation, valid for temperatures T>T(K), with T(K) as the Kondo temperature. We evaluate this expression analytically assuming either weak or strong couplings, and demonstrate that our results agree with exact relations. Far-from-equilibrium situations are further examined, showing a close correspondence to the linear response limit.

  8. A numerical study of local variations in tidal regime of Tagus estuary, Portugal.

    Science.gov (United States)

    Dias, João Miguel; Valentim, Juliana Marques; Sousa, Magda Catarina

    2013-01-01

    Tidal dynamics of shallow estuaries and lagoons is a complex matter that has attracted the attention of a large number of researchers over the last few decades. The main purpose of the present work is to study the intricate tidal dynamics of the Tagus estuary, which states as the largest estuary of the Iberian Peninsula and one of the most important wetlands in Portugal and Europe. Tagus has large areas of low depth and a remarkable geomorphology, both determining the complex propagation of tidal waves along the estuary of unknown manner. A non-linear two-dimensional vertically integrated hydrodynamic model was considered to be adequate to simulate its hydrodynamics and an application developed from the SIMSYS2D model was applied to study the tidal propagation along the estuary. The implementation and calibration of this model revealed its accuracy to predict tidal properties along the entire system. Several model runs enabled the analysis of the local variations in tidal dynamics, through the interpretation of amplitude and phase patterns of the main tidal constituents, tidal asymmetry, tidal ellipses, form factor and tidal dissipation. Results show that Tagus estuary tidal dynamics is extremely dependent on an estuarine resonance mode for the semi-diurnal constituents that induce important tidal characteristics. Besides, the estuarine coastline features and topography determines the changes in tidal propagation along the estuary, which therefore result essentially from a balance between convergence/divergence and friction and advection effects, besides the resonance effects.

  9. Uranium series disequilibrium: application to studies of the groundwater regime of the Harwell region

    International Nuclear Information System (INIS)

    Ivanovich, M.; Alexander, J.

    1985-03-01

    Regional groundwater systems incorporating argillaceous formations beneath the Harwell site have been studied as part of a national research programme of investigation into the feasibility of disposal of low and intermediate radioactive wastes into argillaceous rocks. The principal aim of the programme is to establish the groundwater flow patterns using hydrogeological and geochemical methods in association with isotope contents and uranium series disequilibrium and thus provide an independent approach to the study of effective permeabilities of clay lithologies in a sedimentary sequence. Thirty four groundwater samples derived from the high permeability formations in the Harwell region have been analysed for uranium and thorium content and 234 U/ 238 U, 230 Th/ 234 U and 230 Th/ 232 Th activity ratios. The uranium isotopic signatures have been interpreted in terms of the regional groundwater circulation and mixing patterns. The most significant zones of groundwater mixing determined from uranium isotopic data are situated just beneath the edge of the confined strata. These zones coincide with the locations of hydraulic lows in the Great Oolite and the Corallian formations towards which the regional groundwaters move. It is concluded that the uranium isotopic signatures can be used to identify water masses and to evaluate mixing of groundwaters in a sedimentary sequence on a regional scale. (author)

  10. Study on Yield and Yield Components of Wheat Genotypes under Different Moisture Regimes

    Directory of Open Access Journals (Sweden)

    E. Mogtader

    2012-10-01

    Full Text Available In order to study grain yield and yield components of 16 advanced wheat lines under rainfed and supplementary irrigation conditions, this research was conducted in randomized block design with 3 replications at Maragheh Research Station during 2008-09 seasons. Analysis of variance revealed significant differences for date to heading, plant height, 1000 kernel weight, tiller number, spike length, seed number per spike, spikelet number per spike, peduncle length, harvest index, leaf, sheath length and grain yield. Results also showed that the lines No. 4 (91-142 a 61/3/F35.70/MO73//1D13.1/MLT and 16 (Azar2 with 1895 and 1878 Kg/ha, lines No. 4 and 7 (YUMAI13/5/NAI60/3/14.53/ODIN//CI13441 with 2132 and 2285 Kg/ha had highest grain yield under rainfed and supplementary irrigated conditions respectively. Based on results these 16 lines and cultivars were grouped in 4 and 3 distinct classes using Ward’s Method of cluster analysis under rainfed and irrigated conditions. Path analysis indicated that vigor at shooting stage, seed number per spike and HI were positive important traits to select lines for high yielding potential in this study. HI and TKW had also positive effects on grain under supplementary irrigation.

  11. Study of dark matter and QCD-charged mediators in the quasidegenerate regime

    Science.gov (United States)

    Davidson, Andrew; Kelso, Chris; Kumar, Jason; Sandick, Pearl; Stengel, Patrick

    2017-12-01

    We study a scenario in which the only light new particles are a Majorana fermion dark matter candidate and one or more QCD-charged scalars, which couple to light quarks. This scenario has several interesting phenomenological features if the new particles are nearly degenerate in mass. In particular, LHC searches for the light scalars have reduced sensitivity, since the visible and invisible products tend to be softer. Moreover, dark matter-scalar coannihilation can allow even relatively heavy dark matter candidates to be consistent thermal relics. Finally, the dark matter nucleon scattering cross section is enhanced in the quasidegenerate limit, allowing direct detection experiments to use both spin-independent and spin-dependent scattering to probe regions of parameter space beyond those probed by the LHC. Although this scenario has a broad application, we phrase this study in terms of the minimal supersymmetric standard model, in the limit where the only light sparticles are a binolike dark matter candidate and light-flavored squarks.

  12. Wind turbine blades: A study of prototypes in a steady regime - Unsteady considerations

    Science.gov (United States)

    Leblanc, R.; Goethals, R.; de Saint Louvent, B.

    1981-11-01

    The results of comparisons of numerical models with experimental results for the performance of prototype wind turbines in steady flows are presented, along with preliminary results on behavior in unsteady flows. The numerical models are based on previous schemes devised for propellers, with modifications for small perturbations, significant radial velocity effects from the wake, and the fact that the speed is induced. Two computational methods are currently used, one a method of short blades, the other the Prandtl lifting line theory. Trials have been run in the T4 wind tunnel using a 3 m horizontal axis machine and a 2.5 m Darrieus. Attention is given to modeling the structural dynamics and turbulent flow structures encountered by wind turbines. Experimental results relating windspeed, angle of attack, and output are presented. Optimization studies have indicated that wind farms will require a 6-7 blade diameter unit spacing to maintain satisfactory group output efficiencies.

  13. Perpetual American vanilla option pricing under single regime change risk: an exhaustive study

    Science.gov (United States)

    Montero, Miquel

    2009-07-01

    Perpetual American options are financial instruments that can be readily exercised and do not mature. In this paper we study in detail the problem of pricing this kind of derivatives, for the most popular flavour, within a framework in which some of the properties—volatility and dividend policy—of the underlying stock can change at a random instant of time but in such a way that we can forecast their final values. Under this assumption we can model actual market conditions because most relevant facts usually entail sharp predictable consequences. The effect of this potential risk on perpetual American vanilla options is remarkable: the very equation that will determine the fair price depends on the solution to be found. Sound results are found under the optics both of finance and physics. In particular, a parallelism among the overall outcome of this problem and a phase transition is established.

  14. Study of plasma characteristics in the cathode regime of a nitrogen glow discharge

    International Nuclear Information System (INIS)

    Margulis, Alvaro

    1987-01-01

    This research thesis reports the study of the cathode region, cathodic sheath and negative glow, of a nitrogen glow discharge. The author first presents general data regarding glow discharges, a description of the experimental installation, and measurements of discharge balancing. In the next part, he precisely describes spectroscopic methods, and the implementation of diagnoses from an experimental point of view as well as in terms of space resolution. Results are then presented and interpreted. Measurements concern space distributions of excited species, the determination of axial and radial concentrations of nitrogen ions, axial variations of rotational temperatures of the different species and variations of nitrogen ion vibrational temperature. The laser optogalvanic effect on the nitrogen molecular ion is resolved in time, and compared with the result of a theoretical model based on the mobility difference between the different nitrogen ions. Finally, the author compares experimental results on ion profiles along the discharge axis with results obtained with theoretical models [fr

  15. Usefulness and utility of NACO regime in the management of sexually transmitted infections: A pilot study

    Directory of Open Access Journals (Sweden)

    Anupam Das

    2017-01-01

    Full Text Available Introduction: Treatment of sexually transmitted infections (STIs has been made easy for field workers due to syndromic approach. The etiological agent responsible for different STI syndromes needs to be validated from time to time so as to guide the therapeutic regimen. Aims and Objectives: The aim of this study was to evaluate the etiological agent for STI syndromes and correlate the syndromic diagnosis with etiological diagnosis. Materials and Methods: The study was conducted over 9 months in all patients attending the STI and Gynaecology Outpatient Department. Syndromic diagnosis was done by STI-trained medical officer of respective clinic. Sample was collected for etiological diagnosis and subjected to relevant investigations. Data were analyzed by applying statistical methods. Results: Among 308 patients (male:female = 1:3.5, no syndromic diagnosis could be made in 11 cases (all females and had premalignant changes on Pap smear. In 68 patients (22.08%, no etiological diagnosis could be arrived at (mostly genital ulcer disease [GUD]-herpetic [H] and vaginal discharge. In cervical discharge syndrome, six patients (16.7% showed gonococcus. In GUD-H syndrome, 37 patients (27.027% were tested positive. In GUD-nonherpetic syndrome, three patients (33.33% were syphilis, granuloma inguinale, and chancroid (1 each. In urethral discharge syndrome, etiology could not be found in 33 cases (45.45%. In vaginal discharge syndrome (n = 217, etiologies were overlapping as follows: trichomonas vaginalis (76.04%, bacterial vaginosis (40%, gonococcus (24%, and undiagnosed (6.5%. Conclusion: The present tool for validation of GUD-H can validate only 27% of cases. Overlap of etiologies is mostly common in vaginal discharge syndrome, wherein malignancies and premalignant conditions are overtreated with kits. Validation can be done only in two-third of cases with the available resources. However, syndromic approach provides the opportunity of treating STI without

  16. Numerical study of bandwidth effect on stimulated Raman backscattering in nonlinear regime

    Science.gov (United States)

    Zhou, H. Y.; Xiao, C. Z.; Zou, D. B.; Li, X. Z.; Yin, Y.; Shao, F. Q.; Zhuo, H. B.

    2018-06-01

    Nonlinear behaviors of stimulated Raman scattering driven by finite bandwidth pumps are studied by one dimensional particle-in-cell simulations. The broad spectral feature of plasma waves and backscattered light reveals the different coupling and growth mechanisms, which lead to the suppression effect before the deep nonlinear stage. It causes nonperiodic plasma wave packets and reduces packet and etching velocities. Based on the negative frequency shift and electron energy distribution, the long-time evolution of instability can be divided into two stages by the relaxation time. It is a critical time after which the alleviation effects of nonlinear frequency shift and hot electrons are replaced by enhancement. Thus, the broadband pump suppresses instability at early time. However, it aggravates in the deep nonlinear stage by lifting the saturation level due to the coupling of the incident pump with each frequency shifted plasma wave. Our simulation results show that the nonlinear effects are valid in a bandwidth range from 2.25% to 3.0%, and the physics are similar within a nearby parameter space.

  17. The study of the volume expansion of aluminum during porous oxide formation at galvanostatic regime

    Energy Technology Data Exchange (ETDEWEB)

    Vrublevsky, I.; Parkoun, V.; Sokol, V.; Schreckenbach, J.; Marx, G

    2004-01-30

    The volume expansion factor of porous alumina, formed by through anodizing of an Al foil of thickness 11.5 {mu}m in the range of current densities of 4-35 mA cm{sup -2} in oxalic and sulfuric acid at 18-24 deg. C has been studied. The microstructure of anodizing samples has been observed using scanning electron microscopy. The thickness of obtained porous alumina films was measured by a mechanical profilometer with a computer signal-processing. The volume expansion factor of porous alumina varied from 1.35 to 1.65. Linear dependences were obtained for the volume expansion factor of porous alumina versus the anodizing voltage and the ionic current-density logarithm versus the inverse volume expansion factor. Unlike oxide formation in sulfuric acid, these dependences have two subsequential rectilinear regions in oxalic acid. This peculiarity of the dependences in oxalic acid was explained by formation of a region of the immobile negative space charge in the barrier Al oxide layer and its influence on the ionic transport.

  18. Simulation study of the sub-terawatt laser wakefield acceleration operated in self-modulated regime

    Science.gov (United States)

    Hsieh, C.-Y.; Lin, M.-W.; Chen, S.-H.

    2018-02-01

    Laser wakefield acceleration (LWFA) can be accomplished by introducing a sub-terawatt (TW) laser pulse into a thin, high-density gas target. In this way, the self-focusing effect and the self-modulation that happened on the laser pulse produce a greatly enhanced laser peak intensity that can drive a nonlinear plasma wave to accelerate electrons. A particle-in-cell model is developed to study sub-TW LWFA when a 0.6-TW laser pulse interacts with a dense hydrogen plasma. Gas targets having a Gaussian density profile or a flat-top distribution are defined for investigating the properties of sub-TW LWFA when conducting with a gas jet or a gas cell. In addition to using 800-nm laser pulses, simulations are performed with 1030-nm laser pulses, as they represent a viable approach to realize the sub-TW LWFA driven by high-frequency, diode-pumped laser systems. The peak density which allows the laser peak power PL˜2 Pc r of self-focusing critical power is favourable for conducting sub-TW LWFA. Otherwise, an excessively high peak density can induce an undesired filament effect which rapidly disintegrates the laser field envelope and violates the process of plasma wave excitation. The plateau region of a flat-top density distribution allows the self-focusing and the self-modulation of the laser pulse to develop, from which well-established plasma bubbles can be produced to accelerate electrons. The process of electron injection is complicated in such high-density plasma conditions; however, increasing the length of the plateau region represents a straightforward method to realize the injection and acceleration of electrons within the first bubble, such that an improved LWFA performance can be accomplished.

  19. A model study of the first ventilated regime of the Arctic Ocean during the early Miocene

    Directory of Open Access Journals (Sweden)

    Bijoy Thompson

    2012-07-01

    Full Text Available The tectonic opening of Fram Strait during the Neogene was a significant geological event that transferred the Arctic Ocean from a poorly ventilated enclosed basin, with weak exchange with the North Atlantic, to a fully ventilated “ocean stage”. Previous tectonic and physical oceanographic analyses suggest that the early Miocene Fram Strait was likely several times narrower and less than half as deep as the present-day 400 km wide and 2550 m deep strait. Here we use an ocean general circulation model with a passive age tracer included to further address the effect of the Fram Strait opening on the early Miocene Arctic Ocean circulation. The model tracer age exhibits strong spatial gradient between the two major Arctic Ocean deep basins: the Eurasian and Amerasian basins. There is a two-layer stratification and the exchange flow through Fram Strait shows a bi-layer structure with a low salinity outflow from the Arctic confined to a relatively thin upper layer and a saline inflow from the North Atlantic below. Our study suggests that although Fram Strait was significantly narrower and shallower during early Miocene, and the ventilation mechanism quite different in our model, the estimated ventilation rates are comparable to the chemical tracer estimates in the present-day Arctic Ocean. Since we achieved ventilation of the Arctic Ocean with a prescribed Fram Strait width of 100 km and sill depth of 1000 m, ventilation may have preceded the timing of a full ocean depth connection between the Arctic Ocean and North Atlantic established through seafloor spreading and the development of the Lena Trough.

  20. Women Authors with/without Gender Studies: the Gendered Regimes of Authority in Hungarian Literary Criticism Today

    Directory of Open Access Journals (Sweden)

    Györgyi Horváth

    2011-01-01

    Full Text Available While in contemporary Hungarian literature women authors are constantly emerging and make themselves much more visible than ever before, the gender bias underlying literary evaluations seem to remain nearly intact. In her study Györgyi Horváth discusses three aspects of the gendered regimes of authority in order to give deeper insights into how gender bias re-produces within the Hungarian context. First, she focuses on lists of literary prize winners and critical rankings of published works (showing how many women writers are present on such lists in absolute numbers and in what percentages, and how their numbers have changed over time. Secondly, she explores the practice of critique writing itself, by analyzing the book review pages in two literary journals between 2007 and 2009 focusing on cases when the issue of “gender” itself comes up in the rhetoric of critics trying to underpin their aesthetic judgments on a given work. And finally, she examines briefly the attitude of contemporary women writers towards Gender Studies. Horváth concludes that Gender Studies in Hungary has not contributed significantly to increasing the prestige of contemporary women writers, most of whom, in turn, do not want to be involved with Gender Studies or feminism at all. She also points out that at present in Hungary there is a general blindness in understanding how gender/power relations permeate aesthetic judgments.

  1. Scenario-Based Case Study Analysis of Asteroid Mitigation in the Short Response Time Regime

    Science.gov (United States)

    Seery, B.; Greenaugh, K. C.

    2017-12-01

    Asteroid impact on Earth is a rare but inevitable occurrence, with potentially cataclysmic consequences. If a pending impact is discovered, mitigation options include civil-defense preparations as well as missions to deflect the asteroid and/or robustly disrupt and disperse it to an extent that only a negligible fraction remains on a threatening path (National Research Council's "Defending the Planet," 2010). If discovered with sufficient warning time, a kinetic impactor can deflect smaller objects, but response delays can rule out the option. If a body is too large to deflect by kinetic impactor, or the time for response is insufficient, deflection or disruption can be achieved with a nuclear device. The use of nuclear ablation is considered within the context of current capabilities, requiring no need for nuclear testing. Existing, well-understood devices are sufficient for the largest known Potentially Hazardous Objects (PHOs). The National Aeronautics and Space Administration/Goddard Space Flight Center and the Department of Energy/National Nuclear Security Administration are collaborating to determine the critical characterization issues that define the boundaries for the asteroid-deflection options. Drawing from such work, we examine the timeline for a deflection mission, and how to provide the best opportunity for an impactor to suffice by minimizing the response time. This integrated problem considers the physical process of the deflection method (impact or ablation), along with the spacecraft, launch capability, risk analysis, and the available intercept flight trajectories. Our joint DOE/NASA team has conducted case study analysis of three distinctly different PHOs, on a hypothetical earth impacting trajectory. The size of the design reference bodies ranges from 100 - 500 meters in diameter, with varying physical parameters such as composition, spin state, and metallicity, to name a few. We assemble the design reference of the small body in question using

  2. Experimental investigation of a multi-stage humidification-dehumidification desalination system heated directly by a cylindrical Fresnel lens solar concentrator

    International Nuclear Information System (INIS)

    Wu, Gang; Zheng, Hongfei; Ma, Xinglong; Kutlu, Cagri; Su, Yuehong

    2017-01-01

    Highlights: • A solar desalination system heated directly by curved Fresnel lens concentrator. • Desalination system is based on the humidification-dehumidification process. • Four-stage multi-effect desalination system is proposed. • Condensation latent heat and residual heat in the brine are recycled and reutilized. • The maximum yield and GOR of the unit can reach 3.4 kg/h and 2.1, respectively. - Abstract: This study demonstrates a multi-stage humidification-dehumidification (HDH) solar desalination system heated directly by a cylindrical Fresnel lens concentrator. In this novel system, the solar radiation is sent directly into desalination unit. That is to say, the solar receiver and the evaporator of the system are a whole in which the black fillers in seawater directly absorb the concentrated solar lights to heat the seawater film to produce the evaporation. The configuration and working processes of the proposed design are described in detail. In order to analyze its performance, a small solar desalination prototype unit incorporated with a cylindrical Fresnel lens concentrator was designed and built in our laboratory. Using three-stage isothermal tandem heating mode, the variation of the fresh water yield rate and the absorber temperature with time were measured experimentally and were compared with theoretical calculations. The experimental results show that the maximum yield of the unit is about 3.4 kg/h, the maximum gained output ratio (GOR) is about 2.1, when the average intensity of solar radiation is about 867 W/m"2. This study indicates that the proposed system has the characteristics of compact structure and GOR high. It still can be improved when the design and operation are optimized further.

  3. Regime shifts under forcing of non-stationary attractors: Conceptual model and case studies in hydrologic systems.

    Science.gov (United States)

    Park, Jeryang; Rao, P Suresh C

    2014-11-15

    We present here a conceptual model and analysis of complex systems using hypothetical cases of regime shifts resulting from temporal non-stationarity in attractor strengths, and then present selected published cases to illustrate such regime shifts in hydrologic systems (shallow aquatic ecosystems; water table shifts; soil salinization). Complex systems are dynamic and can exist in two or more stable states (or regimes). Temporal variations in state variables occur in response to fluctuations in external forcing, which are modulated by interactions among internal processes. Combined effects of external forcing and non-stationary strengths of alternative attractors can lead to shifts from original to alternate regimes. In systems with bi-stable states, when the strengths of two competing attractors are constant in time, or are non-stationary but change in a linear fashion, regime shifts are found to be temporally stationary and only controlled by the characteristics of the external forcing. However, when attractor strengths change in time non-linearly or vary stochastically, regime shifts in complex systems are characterized by non-stationary probability density functions (pdfs). We briefly discuss implications and challenges to prediction and management of hydrologic complex systems. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Experimental study for flow regime of downward air-water two-phase flow in a vertical narrow rectangular channel

    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.

  5. Stop grating for perfect replication of micro Fresnel lens by thermal imprinting

    International Nuclear Information System (INIS)

    Gao, Yulong; Lin, Jie; Jin, Peng; Tan, Jiubin; Davies, Graham; Prewett, Philip D

    2012-01-01

    A stop grating concept is proposed to improve polymer filling in the thermal imprinting of a micro Fresnel lens structure. The stop grating consists of line and space structures outside the Fresnel lens pattern zone area. The experimental results have proved that the stop grating can help to achieve the complete filling of a mold, at the same time acting as a stop to prevent possible damage to the mold surface relief structures during imprinting press. A computer simulation was carried out to identify the phenomena of micro-holes at the edge of imprinted pattern. By removing the cavity between the pattern area and stop grating, perfect imprinting results have been achieved. (paper)

  6. Sub-100 nm hard X-ray microbeam generation with Fresnel zone plate optics

    CERN Document Server

    Takano, H; Takeuchi, A

    2003-01-01

    A hard X-ray focusing test of a Fresnel zone plate has been performed with a synchrotron radiation source at the undulator beamline 20XU of SPring-8. Fresnel zone plate with a radius of 150 mu m, and an outermost zone width of 100 nm was used for the X-ray focusing device. The 248-m-long beamline provides fully coherent illumination for the focusing device. The focused beam evaluated by the knife-edge-scan method and scanning microscope test using test charts. Nearly diffraction- limited focusing with a size of 120 nm was achieved for the first-order diffraction at 10 keV X-ray. Evaluation for the third order diffraction was also performed at 8 keV X-ray, and a focal size of 50 m has been obtained. (author)

  7. Um experimento simples usado na produção de placas de zonas de Fresnel

    OpenAIRE

    Muller,Márcia; Silva,Jean Carlos Cardozo da; Fabris,José Luís

    2005-01-01

    Neste trabalho propomos um experimento simples que tem por finalidade auxiliar no aprendizado dos fenômenos de interferência e difração da luz. Após uma análise pertinente da teoria de Fresnel da difração, os conhecimentos são aplicados na compreensão do funcionamento das placas de zonas de Fresnel. Apresentamos uma descrição detalhada dos processos usados para a fabricação e caracterização destas placas zonais, o que possibilita a produção de lentes difrativas com a distância focal desejada ...

  8. Characterization of a photovoltaic-thermal module for Fresnel linear concentrator

    International Nuclear Information System (INIS)

    Chemisana, D.; Ibanez, M.; Rosell, J.I.

    2011-01-01

    Highlights: → A combined domed Fresnel lens - CPC PVT system is designed and characterized. → Electrical and thermal experiments have been performed. → CFD analysis has been used to determine thermal characteristic dimensionless numbers. - Abstract: An advanced solar unit is designed to match the needs of building integration and concentrating photovoltaic/thermal generation. The unit proposed accurately combines three elements: a domed linear Fresnel lens as primary concentrator, a compound parabolic reflector as secondary concentrator and a photovoltaic-thermal module. In this work the photovoltaic-thermal generator is built, analysed and characterized. Models for the electrical and thermal behaviour of the module are developed and validated experimentally. Applying a thermal resistances approach the results from both models are combined. Finally, efficiency electrical and thermal curves are derived from theoretical analysis showing good agreement with experimental measurements.

  9. A perfect Fresnel acoustic reflector implemented by a Fano-resonant metascreen

    KAUST Repository

    Amin, M.

    2018-04-10

    We propose a perfectly reflecting acoustic metasurface which is designed by replacing the curved segments of the traditional Fresnel reflector by flat Fano-resonant sub-wavelength unit cells. To preserve the original Fresnel focusing mechanism, the unit cell phase follows a specific phase profile which is obtained by applying the generalized Snell\\'s law and Fermat\\'s principle. The reflected curved phase fronts are thus created at the air-metasurface boundary by tailoring the metasurface dispersion as dictated by Huygens\\' principle. Since the unit cells are implemented by sub-wavelength double slit-shaped cavity resonators, the impinging sound waves are perfectly reflected producing acoustic focusing with negligible absorption. We use plane-wave solution and full-wave simulations to demonstrate the focusing effects. The simulation results closely follow the analytical predictions.

  10. A perfect Fresnel acoustic reflector implemented by a Fano-resonant metascreen

    KAUST Repository

    Amin, M.; Siddiqui, O.; Farhat, Mohamed; Khelif, A.

    2018-01-01

    We propose a perfectly reflecting acoustic metasurface which is designed by replacing the curved segments of the traditional Fresnel reflector by flat Fano-resonant sub-wavelength unit cells. To preserve the original Fresnel focusing mechanism, the unit cell phase follows a specific phase profile which is obtained by applying the generalized Snell's law and Fermat's principle. The reflected curved phase fronts are thus created at the air-metasurface boundary by tailoring the metasurface dispersion as dictated by Huygens' principle. Since the unit cells are implemented by sub-wavelength double slit-shaped cavity resonators, the impinging sound waves are perfectly reflected producing acoustic focusing with negligible absorption. We use plane-wave solution and full-wave simulations to demonstrate the focusing effects. The simulation results closely follow the analytical predictions.

  11. Aliasless fresnel transform image reconstruction in phase scrambling fourier transform technique by data interpolation

    International Nuclear Information System (INIS)

    Yamada, Yoshifumi; Liu, Na; Ito, Satoshi

    2006-01-01

    The signal in the Fresnel transform technique corresponds to a blurred one of the spin density image. Because the amplitudes of adjacent sampled signals have a high interrelation, the signal amplitude at a point between sampled points can be estimated with a high degree of accuracy even if the sampling is so coarse as to generate aliasing in the reconstructed images. In this report, we describe a new aliasless image reconstruction technique in the phase scrambling Fourier transform (PSFT) imaging technique in which the PSFT signals are converted to Fresnel transform signals by multiplying them by a quadratic phase term and are then interpolated using polynomial expressions to generate fully encoded signals. Numerical simulation using MR images showed that almost completely aliasless images are reconstructed by this technique. Experiments using ultra-low-field PSFT MRI were conducted, and aliasless images were reconstructed from coarsely sampled PSFT signals. (author)

  12. Fresnel diffraction correction by phase-considered iteration procedure in soft X-ray projection microscopy

    International Nuclear Information System (INIS)

    Shiina, Tatsuo; Suzuki, Tsuyoshi; Honda, Toshio; Ito, Atsushi; Kinjo, Yasuhito; Yoshimura, Hideyuki; Yada, Keiji; Shinohara, Kunio

    2009-01-01

    In soft X-ray projection microscopy, it is easy to alter the magnification by changing the distance between the pinhole and the specimen, while the image is blurred because the soft X-rays are diffracted through the propagation from specimen to CCD detector. We corrected the blurred image by the iteration procedure of Fresnel to inverse Fresnel transformation taking phase distribution of the specimen into account. The experiments were conducted at the BL-11A of the Photon Factory, KEK, Japan for the specimens such as glass-capillaries, latex-particles, dried mammalian cells and human chromosomes. Many of those blurred images were corrected adequately by the iteration procedure, though some images such as those which have high-contrast or are overlapped by small cells still remain to be improved.

  13. A perfect Fresnel acoustic reflector implemented by a Fano-resonant metascreen

    Science.gov (United States)

    Amin, M.; Siddiqui, O.; Farhat, M.; Khelif, A.

    2018-04-01

    We propose a perfectly reflecting acoustic metasurface which is designed by replacing the curved segments of the traditional Fresnel reflector by flat Fano-resonant sub-wavelength unit cells. To preserve the original Fresnel focusing mechanism, the unit cell phase follows a specific phase profile which is obtained by applying the generalized Snell's law and Fermat's principle. The reflected curved phase fronts are thus created at the air-metasurface boundary by tailoring the metasurface dispersion as dictated by Huygens' principle. Since the unit cells are implemented by sub-wavelength double slit-shaped cavity resonators, the impinging sound waves are perfectly reflected producing acoustic focusing with negligible absorption. We use plane-wave solution and full-wave simulations to demonstrate the focusing effects. The simulation results closely follow the analytical predictions.

  14. Origin of two time-scale regimes in potentiometric titration of metal oxides. A replica kinetic Monte Carlo study

    International Nuclear Information System (INIS)

    Zarzycki, Piotr P.; Rosso, Kevin M.

    2009-01-01

    Replica Kinetic Monte Carlo simulations were used to study the characteristic time scales of potentiometric titration of the metal oxides and (oxy)hydroxides. The effect of surface heterogeneity and surface transformation on the titration kinetics were also examined. Two characteristic relaxation times are often observed experimentally, with the trailing slower part attributed to surface non-uniformity, porosity, polymerization, amorphization, and other dynamic surface processes induced by unbalanced surface charge. However, our simulations show that these two characteristic relaxation times are intrinsic to the proton binding reaction for energetically homogeneous surfaces, and therefore surface heterogeneity or transformation do not necessarily need to be invoked. However, all such second-order surface processes are found to intensify the separation and distinction of the two kinetic regimes. The effect of surface energetic-topographic non-uniformity, as well dynamic surface transformation, interface roughening/smoothing were described in a statistical fashion. Furthermore, our simulations show that a shift in the point-of-zero charge is expected from increased titration speed and the pH-dependence of the titration measurement error is in excellent agreement with experimental studies.

  15. Origin of two time-scale regimes in potentiometric titration of metal oxides. A replica kinetic Monte Carlo study.

    Science.gov (United States)

    Zarzycki, Piotr; Rosso, Kevin M

    2009-06-16

    Replica kinetic Monte Carlo simulations were used to study the characteristic time scales of potentiometric titration of the metal oxides and (oxy)hydroxides. The effect of surface heterogeneity and surface transformation on the titration kinetics were also examined. Two characteristic relaxation times are often observed experimentally, with the trailing slower part attributed to surface nonuniformity, porosity, polymerization, amorphization, and other dynamic surface processes induced by unbalanced surface charge. However, our simulations show that these two characteristic relaxation times are intrinsic to the proton-binding reaction for energetically homogeneous surfaces, and therefore surface heterogeneity or transformation does not necessarily need to be invoked. However, all such second-order surface processes are found to intensify the separation and distinction of the two kinetic regimes. The effect of surface energetic-topographic nonuniformity, as well dynamic surface transformation, interface roughening/smoothing were described in a statistical fashion. Furthermore, our simulations show that a shift in the point-of-zero charge is expected from increased titration speed, and the pH-dependence of the titration measurement error is in excellent agreement with experimental studies.

  16. Fresnel's original interpretation of complex numbers in 19th century optics

    DEFF Research Database (Denmark)

    Avelar Sotomaior Karam, Ricardo

    2018-01-01

    In 1823, Fresnel published an original (physical) interpretation of complex numbers in his investigations of refraction and reflection of polarized light. This is arguably the first time that complex numbers were given a physical interpretation, which led to a better understanding of elliptical a...... and circular polarizations. This rather unknown episode of the history of physics is described in this work, and some of the pedagogical lessons that can be extracted from it are discussed....

  17. Fresnel's original interpretation of complex numbers in 19th century optics

    Science.gov (United States)

    Karam, Ricardo

    2018-04-01

    In 1823, Fresnel published an original (physical) interpretation of complex numbers in his investigations of refraction and reflection of polarized light. This is arguably the first time that complex numbers were given a physical interpretation, which led to a better understanding of elliptical and circular polarizations. This rather unknown episode of the history of physics is described in this work, and some of the pedagogical lessons that can be extracted from it are discussed.

  18. Chromatic aberration compensation in numerical reconstruction of digital holograms by Fresnel-Bluestein propagation.

    Science.gov (United States)

    Hincapie, Diego; Velasquez, Daniel; Garcia-Sucerquia, Jorge

    2017-12-15

    In this Letter, we present a method for chromatic compensation in numerical reconstruction of digitally recorded holograms based on Fresnel-Bluestein propagation. The proposed technique is applied to correct the chromatic aberration that arises in the reconstruction of RGB holograms of both millimeter- and micrometer-sized objects. The results show the feasibility of this strategy to remove the wavelength dependence of the size of the numerically propagated wavefields.

  19. Fresnel zone plate imaging of a 252Cf spontaneous fission source

    International Nuclear Information System (INIS)

    Stalker, K.T.; Hessel, K.R.

    1976-11-01

    The feasibility of coded aperture imaging for nuclear fuel motion monitoring is shown using Cf 252 spontaneous fission source. The theory of coded aperture imaging for Fresnel zone plate apertures is presented and design considerations for zone plate construction are discussed. Actual images are obtained which demonstrate a transverse resolution of 1.7 mm and a tomographic resolution of 1.5 millimeters. The capability of obtaining images through 12.7 mm of stainless steel is also shown

  20. Visual persuasion and politics: ideology and symbols of the totalitarian regimes'--case study: hammer and sickle.

    Science.gov (United States)

    Svilicić, Niksa; Maldini, Pero

    2013-06-01

    Unlike all other autocracies, authoritarian regimes are, as the ultimate form of authoritarianism, a distinct phenomenon of the modern era. Caused by the crisis of liberal democracy and industrial capitalism of the early twentieth century, and led by radical populist political movements/parties and their leaders, they established themselves as the regimes which marked one of the greatest degrees of unfreedom. The article analyzes the specific sociostructural, sociocultural and sociopsychological aspects of the formation of totalitarian regimes (particularly communism), as well as their political system, ideological foundations and modus operandi. In doing so, it particularly emphasizes the dissolution of civil society and its substitution by a political society as a key structural determinant, authoritarianism and fear as a sociopsychological basis, and repression as the functional basis of operation for totalitarian regimes. In that context, it analyzes the political, anthropological and visual aspects of the symbols of totalitarian regimes, their archetypal (mythological, religious, ethnic, cultural, historical) meaning, and explains their function (political, anthropological, sociocultural, and sociopsychological) in the development and preservation of totalitarian regimes. Using the example of the hammer and sickle, a typical symbol of communism, it shows a substantial and communicational (particularly visual) dimension of symbol, by breakdown by the elements of semiotics (signum, designatum, interpretant) and its sub-disciplines (semantics, pragmatics, sintactics). On this basis, it tries to show the decisive power of political symbols over the political perceptions and political behavior of individuals and entire social groups, i.e. their manipulative power by meanings assigned to them by totalitarian authorities and forms of their communication, with the goal of preserving the totalitarian regime.

  1. Diamond turning of small Fresnel lens array in single crystal InSb

    International Nuclear Information System (INIS)

    Jasinevicius, R G; Duduch, J G; Cirino, G A; Pizani, P S

    2013-01-01

    A small Fresnel lens array was diamond turned in a single crystal (0 0 1) InSb wafer using a half-radius negative rake angle (−25°) single-point diamond tool. The machined array consisted of three concave Fresnel lenses cut under different machining sequences. The Fresnel lens profiles were designed to operate in the paraxial domain having a quadratic phase distribution. The sample was examined by scanning electron microscopy and an optical profilometer. Optical profilometry was also used to measure the surface roughness of the machined surface. Ductile ribbon-like chips were observed on the cutting tool rake face. No signs of cutting edge wear was observed on the diamond tool. The machined surface presented an amorphous phase probed by micro Raman spectroscopy. A successful heat treatment of annealing was carried out to recover the crystalline phase on the machined surface. The results indicated that it is possible to perform a ‘mechanical lithography’ process in single crystal semiconductors. (paper)

  2. Large Dam Effects on Flow Regime and Hydraulic Parameters of river (Case study: Karkheh River, Downstream of Reservoir Dam

    Directory of Open Access Journals (Sweden)

    Farhang Azarang

    2017-06-01

    Full Text Available Introduction: The critical role of the rivers in supplying water for various needs of life has led to engineering identification of the hydraulic regime and flow condition of the rivers. Hydraulic structures such dams have inevitable effects on their downstream that should be well investigated. The reservoir dams are the most important hydraulic structures which are the cause of great changes in river flow conditions. Materials and Methods: In this research, an accurate assessment was performed to study the flow regime of Karkheh river at downstream of Karkheh Reservoir Dam as the largest dam in Middle East. Karkheh River is the third waterful river of Iran after Karun and Dez and the third longest river after the Karun and Sefidrud. The Karkheh Dam is a large reservoir dam built in Iran on the Karkheh River in 2000. The Karkheh Reservoir Dam is on the Karkheh River in the Northwestern Khouzestan Province, the closest city being Andimeshk to the east. The part of Karkheh River, which was studied in this research is located at downstream of Karkheh Reservoir Dam. This interval is approximately 94 km, which is located between PayePol and Abdolkhan hydrometric stations. In this research, 138 cross sections were used along Karkheh River. Distance of cross sections from each other was 680m in average. The efficient model of HEC-RAS has been utilized to simulate the Karkheh flow conditions before and after the reservoir dam construction using of hydrometric stations data included annually and monthly mean discharges, instantaneous maximum discharges, water surface profiles and etc. Three defined discharges had been chosen to simulate the Karkheh River flow; maximum defined discharge, mean defined discharge and minimum defined discharge. For each of these discharges values, HEC-RAS model was implemented as a steady flow of the Karkheh River at river reach of study. Water surface profiles of flow, hydraulic parameters and other results of flow regime in

  3. A Study on Current Status of Detection Technology and Establishment of National Detection Regime against Nuclear/Radiological Terrorism

    International Nuclear Information System (INIS)

    Kwak, Sung Woo; Jang, Sung Soon; Lee, Joung Hoon; Yoo, Ho Sik

    2009-01-01

    Since 1990s, some events - detection of a dirty bomb in a Russian nation park in 1995, 9/11 terrorist attack to WTC in 2001, discovery of Al-Qaeda's experimentation to build a dirty bomb in 2003 etc - have showed that nuclear or radiological terrorism relating to radioactive materials (hereinafter 'radioactive materials' is referred to as 'nuclear material, nuclear spent fuel and radioactive source') is not incredible but serious and credible threat. Thus, to respond to the new threat, the international community has not only strengthened security and physical protection of radioactive materials but also established prevention of and response to illicit trafficking of radioactive materials. In this regard, our government has enacted or revised the national regulatory framework with a view to improving security of radioactive materials and joined the international convention or agreement to meet this international trend. For the purpose of prevention of nuclear/radiological terrorism, this paper reviews physical characteristics of nuclear material and existing detection instruments used for prevention of illicit trafficking. Finally, national detection regime against nuclear/radiological terrorism based on paths of the smuggled radioactive materials to terrorist's target building/area, national topography and road networks, and defence-in-depth concept is suggested in this paper. This study should contribute to protect people's health, safety and environment from nuclear/radiological terrorism

  4. Atomic-scale study of the adsorption of calcium fluoride on Si(100) at low-coverage regime

    International Nuclear Information System (INIS)

    Chiaravalloti, Franco; Dujardin, Gerald; Riedel, Damien; Pinto, Henry P.; Foster, Adam S.

    2011-01-01

    We investigate, experimentally and theoretically, the initial stage of the formation of Ca/Si and Si/F structures that occurs during the adsorption of CaF 2 molecules onto a bare Si(100) surface heated to 1000 K in a low-coverage regime (0.3 monolayer). A low-temperature (5 K) scanning tunneling microscope (STM) is used to observe the topographies and the electronic properties of the exposed silicon surfaces. Our atomic-scale study reveals that several chemical reactions arise during CaF 2 deposition, such as dissociation of the CaF 2 molecules and etching of the surface silicon dimers. The experimental and calculated STM topographies are compared using the density functional theory, and this comparison enables us to identify two types of reacted structures on the Si(100) surface. The first type of observed complex surface structure consists of large islands formed with a semiperiodic sequence of 3 x 2 unit cells. The second one is made of isolated Ca adatoms adsorbed at specific sites on the Si(100)-2 x 1 surface.

  5. Dynamic crossovers and activated regimes in a narrow distribution poly(n-butyl acrylate): an ESR study

    Energy Technology Data Exchange (ETDEWEB)

    Andreozzi, Laura; Autiero, Ciro; Faetti, Massimo; Giordano, Marco; Zulli, Fabio [Department of Physics ' E Fermi' , University of Pisa, largo Pontecorvo 3, 56127 Pisa (Italy); polyLAB-CNR, largo Pontecorvo 3, 56127 Pisa (Italy)

    2006-07-19

    The rotational dynamics of the spin probe cholestane dissolved in a narrow distribution poly(n-butyl acrylate) sample has been investigated via electron spin resonance (ESR) spectroscopy. The measurements were carried out in a wide temperature range: different dynamic regions have been recognized, and the coupling of the probe dynamics to the {alpha} and secondary relaxations has been revealed. In particular, the coupling with the structural relaxation is ruled by two fractionary Vogel-Fulcher laws (VF). The crossover from one VF region to the other occurs at the temperature T{sub C} = 1.17T{sub g}, signalling the onset of the cooperativity in the dynamics and confirming a behaviour previously observed in ESR studies carried out on polymeric glass-formers. Furthermore, in this work we discuss the activated regime at the highest temperatures and show that the activation energy does not depend on the length of the polymer main- and side-chains, while its onset temperature linearly depends on the chain length.

  6. Dynamic crossovers and activated regimes in a narrow distribution poly(n-butyl acrylate): an ESR study

    International Nuclear Information System (INIS)

    Andreozzi, Laura; Autiero, Ciro; Faetti, Massimo; Giordano, Marco; Zulli, Fabio

    2006-01-01

    The rotational dynamics of the spin probe cholestane dissolved in a narrow distribution poly(n-butyl acrylate) sample has been investigated via electron spin resonance (ESR) spectroscopy. The measurements were carried out in a wide temperature range: different dynamic regions have been recognized, and the coupling of the probe dynamics to the α and secondary relaxations has been revealed. In particular, the coupling with the structural relaxation is ruled by two fractionary Vogel-Fulcher laws (VF). The crossover from one VF region to the other occurs at the temperature T C = 1.17T g , signalling the onset of the cooperativity in the dynamics and confirming a behaviour previously observed in ESR studies carried out on polymeric glass-formers. Furthermore, in this work we discuss the activated regime at the highest temperatures and show that the activation energy does not depend on the length of the polymer main- and side-chains, while its onset temperature linearly depends on the chain length

  7. Numerical and experimental study of the slug-flow regime in a mixture of castor and paraffin oils in a T-type microchannel

    Science.gov (United States)

    Minakov, A. V.; Shebeleva, A. A.; Yagodnitsyna, A. A.; Kovalev, A. V.; Bilsky, A. V.

    2017-09-01

    The slow-flug regime in a mixture of castor and paraffin oils in a T-type microchannel with crosssectional dimensions of 200 × 400 μm has been studied by numerical and experimental methods. The domain of existence of the slow-flug regime in this system has been determined. Dependence of the paraffin-oil slug length on the ratio of flow rates of the mixture components is established. Comparison of the calculated and experimental data shows their good agreement.

  8. Impacts of Land Use Change on the Natural Flow Regime: A Case Study in the Meramec River Watershed in Eastern Missouri, USA

    Science.gov (United States)

    Wu, C. L.; Knouft, J.; Chu, M.

    2017-12-01

    The natural flow regime within a watershed can be considered as the expected temporal patterns of streamflow variation in the absence of human impacts. While ecosystems have evolved to function under these conditions, the natural flow regime of most rivers has been significantly altered by human activities. Land use change, including the development of agriculture and urbanization, is a primary cause of the loss of natural flow regimes. These changes have altered discharge volume, timing, and variability, and consequently affected the structure and functioning of river ecosystems. The Meramec River watershed is located in east central Missouri and changes in land use have been the primary factor impacting flow regimes across the watershed. In this study, a watershed model, the Soil and Water Assessment Tool (SWAT), was developed to simulate a long-term time series of streamflow (1978-2014) within the watershed. Model performance was evaluated using statistical metrics and graphical technique including R-squared, Nash-Sutcliffe efficiency, cumulative error, and 1:1-ratio comparison between observed and simulated variables. The calibrated and validated SWAT model was then used to quantify the responses of the watershed when it was a forested natural landscape. An Indicator of Hydrologic Alteration (IHA) approach was applied to characterize the flow regime under the current landcover conditions as well as the simulated natural flow regime under the no land use change scenario. Differences in intra- and inter-annual ecologically relevant flow metrics were then compared using SWAT model outputs in conjunction with the IHA approach based on model outputs from current and no land use change conditions. This study provides a watershed-scale understanding of effects of land use change on a river's flow variability and provides a framework for the development of restoration plans for heavily altered watersheds.

  9. Updates of CORESTA Recommended Methods after Further Collaborative Studies Carried Out under Both ISO and Health Canada Intense Smoking Regimes

    Directory of Open Access Journals (Sweden)

    Purkis SW

    2014-12-01

    Full Text Available During 2012, three CORESTA Recommended Methods (CRMs (1-3 were updated to include smoke yield and variability data under both ISO (4 and the Canadian Intense (CI (5 smoking regimes. At that time, repeatability and reproducibility data under the CI regime on smoke analytes other than “tar”, nicotine and carbon monoxide (6 and tobacco-specific nitrosamines (TSNAs (7 were not available in the public literature. The subsequent work involved the determination of the mainstream smoke yields of benzo[a]-pyrene, selected volatiles (benzene, toluene, 1,3-butadiene, isoprene, acrylonitrile, and selected carbonyls (acetaldehyde, formaldehyde, propionaldehyde, butyraldehyde, crotonaldehyde, acrolein, acetone and 2-butanone in ten cigarette products followed by statistical analyses according to the ISO protocol (8. This paper provides some additional perspective on the data variability under the ISO and CI smoking regimes not given in the CRMs.

  10. Study of volume fractions for stratified and annular regime in multiphase flows using gamma-rays and artificial neural network

    International Nuclear Information System (INIS)

    Salgado, Cesar M.; Brandao, Luis Eduardo; Pereira, Claudio M.N.A.; Ramos, Robson; Schirru, Roberto; Silva, Ademir X.

    2007-01-01

    This work presents methodology based on the use of nuclear technique and artificial intelligence for attainment of volume fractions in stratified and annular multiphase flow regime, oil-water-gas, very frequent in the offshore industry petroliferous. Using the principles of absorption and scattering of gamma-rays and an adequate geometry scheme of detection with two detectors and two energies measurement are gotten and they vary as changes in the volume fractions of flow regime occur. The MCNP-X code was used in order to provide the data training for artificial neural network that matched such information with the respective actual volume fractions of each material. (author)

  11. Study of volume fractions for stratified and annular regime in multiphase flows using gamma-rays and artificial neural network

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, Cesar M.; Brandao, Luis Eduardo; Pereira, Claudio M.N.A.; Ramos, Robson [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)]. E-mail: otero@ien.gov.br; brandao@ien.gov.br; cmnap@ien.gov.br; robson@ien.gov.br; Schirru, Roberto; Silva, Ademir X. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE). Programa de Energia Nuclear (PEN)]. E-mails: ademir@con.ufrj.br; schirru@lmp.ufrj.br

    2007-07-01

    This work presents methodology based on the use of nuclear technique and artificial intelligence for attainment of volume fractions in stratified and annular multiphase flow regime, oil-water-gas, very frequent in the offshore industry petroliferous. Using the principles of absorption and scattering of gamma-rays and an adequate geometry scheme of detection with two detectors and two energies measurement are gotten and they vary as changes in the volume fractions of flow regime occur. The MCNP-X code was used in order to provide the data training for artificial neural network that matched such information with the respective actual volume fractions of each material. (author)

  12. Post-operative recovery profile after laparoscopic cholecystectomy: a prospective, observational study of a multimodal anaesthetic regime

    DEFF Research Database (Denmark)

    Jensen, K; Kehlet, H; Lund, Claus

    2007-01-01

    functions. We investigated the feasibility and efficacy of a standardized, evidence-based anaesthesia/analgesic regime to identify residual problems in the early post-operative phase. METHODS: One hundred and thirty-four consecutive patients admitted for elective laparoscopic cholecystectomy at Hvidovre...

  13. A 3D CFD Modelling Study of a Diesel Oil Evaporation Device Operating in the Stabilized Cool Flame Regime

    Directory of Open Access Journals (Sweden)

    Dionysios I. Kolaitis

    2010-12-01

    Full Text Available Diesel fuel is used in a variety of technological applications due to its high energy density and ease of distribution and storage. Motivated by the need to use novel fuel utilization techniques, such as porous burners and fuel cells, which have to be fed with a gaseous fuel, a Diesel fuel evaporation device, operating in the “Stabilized Cool Flame” (SCF regime, is numerically investigated. In this device, a thermo-chemically stable low-temperature oxidative environment is developed, which produces a well-mixed, heated air-fuel vapour gaseous mixture that can be subsequently fed either to premixed combustion systems or fuel reformer devices for fuel cell applications. In this work, the ANSYS CFX 11.0 CFD code is used to simulate the three-dimensional, turbulent, two-phase, multi-component and reacting flow-field, developed in a SCF evaporation device. An innovative modelling approach, based on the fitting parameter concept, has been developed in order to simulate cool flame reactions. The model, based on physico-chemical reasoning coupled with information from available experimental data, is implemented in the CFD code and is validated by comparing numerical predictions to experimental data obtained from an atmospheric pressure, recirculating flow SCF device. Numerical predictions are compared with temperature measurements, achieving satisfactory levels of agreement. The developed numerical tool can effectively support the theoretical study of the physical and chemical phenomena emerging in practical devices of liquid fuel spray evaporation in a SCF environment, as well as the design optimisation process of such innovative devices.

  14. Study of the mobility, surface area, and sintering behavior of agglomerates in the transition regime by tandem differential mobility analysis

    International Nuclear Information System (INIS)

    Cho, Kuk; Hogan, Christopher J.; Biswas, Pratim

    2007-01-01

    The surface area of nanosized agglomerates is of great importance as the reactivity and health effects of such particles are highly dependent on surface area. Changes in surface area through sintering during nanoparticle synthesis processes are also of interest for precision control of synthesised particles. Unfortunately, information on particle surface area and surface area dynamics is not readily obtainable through traditional particle mobility sizing techniques. In this study, we have experimentally determined the mobility diameter of transition regime agglomerates with 3, 4, and 5 primary particles. Agglomerates were produced by spray drying well-characterised polystyrene latex particles with diameters of 55, 67, 76, and 99 nm. Tandem differential mobility analysis was used to determine agglomerate mobility diameter by selecting monodisperse agglomerates with the same number of primary particles in the first DMA, and subsequently completely sintering the agglomerates in a furnace aerosol reactor. The size distribution of the completely sintered particles was measured by an SMPS system, which allowed for the determination of the number of primary particles in the agglomerates. A simple power law regression was used to express mobility diameter as a function of primary particle size and the number of primary particles, and had an excellent correlation (R 2 = 0.9971) with the experimental data. A scaling exponent was determined from the experimental data to relate measured mobility diameter to surface area for agglomerates. Using this relationship, the sintering characteristics of agglomerates were also examined for varying furnace temperatures and residence times. The sintering data agreed well with the geometric sintering model (GSM) model proposed by Cho and Biswas (2006a) as well as with the model proposed Koch and Friedlander (1990) for sintering by viscous flow

  15. Experimental study of linear and nonlinear regimes of density-driven instabilities induced by CO{sub 2} dissolution in water

    Energy Technology Data Exchange (ETDEWEB)

    Outeda, R.; D' Onofrio, A. [Grupo de Medios Porosos, Facultad de Ingeniería, Universidad de Buenos Aires, Paseo Colón 850, C1063ACV Buenos Aires (Argentina); El Hasi, C.; Zalts, A. [Instituto de Ciencias, Universidad Nacional General Sarmiento, J. M. Gutiérrez 1150, B1613GSX, Los Polvorines, Provincia de Buenos Aires (Argentina)

    2014-03-15

    Density driven instabilities produced by CO{sub 2} (gas) dissolution in water containing a color indicator were studied in a Hele Shaw cell. The images were analyzed and instability patterns were characterized by mixing zone temporal evolution, dispersion curves, and the growth rate for different CO{sub 2} pressures and different color indicator concentrations. The results obtained from an exhaustive analysis of experimental data show that this system has a different behaviour in the linear regime of the instabilities (when the growth rate has a linear dependence with time), from the nonlinear regime at longer times. At short times using a color indicator to see the evolution of the pattern, the images show that the effects of both the color indicator and CO{sub 2} pressure are of the same order of magnitude: The growth rates are similar and the wave numbers are in the same range (0–30 cm{sup −1}) when the system is unstable. Although in the linear regime the dynamics is affected similarly by the presence of the indicator and CO{sub 2} pressure, in the nonlinear regime, the influence of the latter is clearly more pronounced than the effects of the color indicator.

  16. Transition from weak wave turbulence regime to solitonic regime

    Science.gov (United States)

    Hassani, Roumaissa; Mordant, Nicolas

    2017-11-01

    The Weak Turbulence Theory (WTT) is a statistical theory describing the interaction of a large ensemble of random waves characterized by very different length scales. For both weak non-linearity and weak dispersion a different regime is predicted where solitons propagate while keeping their shape unchanged. The question under investigation here is which regime between weak turbulence or soliton gas does the system choose ? We report an experimental investigation of wave turbulence at the surface of finite depth water in the gravity-capillary range. We tune the wave dispersion and the level of nonlinearity by modifying the depth of water and the forcing respectively. We use space-time resolved profilometry to reconstruct the deformed surface of water. When decreasing the water depth, we observe a drastic transition between weak turbulence at the weakest forcing and a solitonic regime at stronger forcing. We characterize the transition between both states by studying their Fourier Spectra. We also study the efficiency of energy transfer in the weak turbulence regime. We report a loss of efficiency of angular transfer as the dispersion of the wave is reduced until the system bifurcates into the solitonic regime. This project has recieved funding from the European Research Council (ERC, Grant Agreement No. 647018-WATU).

  17. Study of cavity effect in micro-Pirani gauge chamber with improved sensitivity for high vacuum regime

    Directory of Open Access Journals (Sweden)

    Guohe Zhang

    2018-05-01

    Full Text Available Ultra-low pressure application of Pirani gauge needs significant improvement of sensitivity and expansion of measureable low pressure limit. However, the performance of Pirani gauge in high vacuum regime remains critical concerns since gaseous thermal conduction with high percentage is essential requirement. In this work, the heat transfer mechanism of micro-Pirani gauge packaged in a non-hermetic chamber was investigated and analyzed compared with the one before wafer-level packaging. The cavity effect, extremely important for the efficient detection of low pressure, was numerically and experimentally analyzed considering the influence of the pressure, the temperature and the effective heat transfer area in micro-Pirani gauge chamber. The thermal conduction model is validated by experiment data of MEMS Pirani gauges with and without capping. It is found that nature gaseous convection in chamber, determined by the Rayleigh number, should be taken into consideration. The experiment and model calculated results show that thermal resistance increases in the molecule regime, and further increases after capping due to the suppression of gaseous convection. The gaseous thermal conduction accounts for an increasing percentage of thermal conduction at low pressure while little changes at high pressure after capping because of the existence of cavity effect improving the sensitivity of cavity-effect-influenced Pirani gauge for high vacuum regime.

  18. Monitoring and analysis of technology transfer and intellectual property regimes and their use results of a study carried out on behalf of the European Commission (DG Research)

    CERN Document Server

    Van Eecke, Patrick; Bolger, P; Truyens, M

    2008-01-01

    This report presents the results of a three-year study commissioned by the European Commission (DG Research) regarding the monitoring, analysis and use of technology transfer and intellectual property regimes in the European Union. This study was organised in the context of the 6th Framework Programme for R&D, and was jointly carried out by law firms Mason Hayes+Curran (Dublin) and DLA Piper (Brussels).

  19. Pegase: safety studies - experimental study of burn-out risks in transient operation; Pegase: etude de surete - etude experimentale des risques de burn out en regime transitoire

    Energy Technology Data Exchange (ETDEWEB)

    Vernier, P [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1968-07-01

    An experiment out-of-pile experimental set up is proposed simulating the breakage of a pipe supplying the core of the reactor Pegase. The two fast phenomena, depressurization of the vessel and flow reversal, are reproduced. The aluminium heating channel has the same shape as that of the reactor channel but has twice the heat capacity. The starting conditions are V= 4.50 and 6 m/sec., T{sub E} = 50 and 60 degrees C and P{sub E} = 4 bars. The results show that the critical flux PHI{sub C} varies with the flow-rate from 45 to 60 W/cm{sup 2} in the case where there is no power reduction. For fluxes of 90 W/cm{sup 2} the results lead to the conclusion that the hot channel attains a state of burn-out after 0.1 sec. and that its temperature reaches 500 C in 0.8 sec. The hydrodynamic conditions in the channels after the accident involve periodic expulsion (0.2 to 0.5 sec.), characteristic of boiling at low pressure. A study of the steady state flow redistribution through a by-pass has given flux redistribution PHI{sub R} of 190 W/cm{sup 2} for a flow rate of 4.5 m/sec. at 50 and of 175 W/cm{sup 2} at 60 C. These values increase which has to be made between the critical flux PHI{sub C} during the periodic expulsion conditions and the flux redistribution PHI{sub R} during the steady state, has been shown. (author) [French] On propose un schema experimental hors pile d'une rupture du tuyau alimentant le coeur du reacteur PEGASE. On reproduit les phenomenes rapides de depressurisation du caisson et d'inversion du debit dans le coeur. Le canal chauffant en aluminium a la meme geometrie que le canal du reacteur, mais une capacite calorifique double. Les conditions initiales sont V= 4.5 et 6 m/s, T{sub E} = 50 et 60 C et P{sub E} = 4 bars. Les resultats montrent que le flux critique PHI{sub C} evolue avec la vitesse de 45 a 60 60 W/cm{sup 2} dans le cas ou il n'y a pas reduction de puissance. Pour des flux de 90 W/cm{sup 2} l'interpretation des resultats permet de conclure que le

  20. Study of recent changes in sedimentation regime inside Cienfuegos Cuban bay, using 210Pb and 137Cs as tracers

    International Nuclear Information System (INIS)

    Alonso Hernandez, C.M.; Diaz Asencio, M.; Munnoz Caravaca, A.; Delfanti, R.; Papucci, C.

    2001-01-01

    Cienfuegos Bay is a semi closed bay with a surface area of 90 km2 and an average depth of 14m, connected to the Caribbean Sea by a narrow channel of about 3 km long. The bay is divided in two well defined hydro graphic cells, due to the presence of a submerged ridge about 1m below the water surface. The northern cell receives most of the anthropic impact from the outfall of Cienfuegos city, industrial pole in the country, and the fluvial supply of Damuji and Salado rivers. The southern cell receives a lower anthropic impact from the Caonao and Arimao river inputs. Part of this southern cell is a natural protected park, which represents a niche of migratory birds and marine species in conservation status.The bay represents the most important natural resource in the province, due to fishing activities, maritime transport, tourism industry, and natural parks. In the last three decades, deleterious ecological signers in the area have been observed. Declining of biodiversity in the ecosystem, bethonic communities' movement, reduction of size and capture levels of commercial marine species, erosion of coastline, could be associated with changes of sedimentation regime in the bay. The distribution of 210Pb, 137Cs in sediments provide, insight into the sedimentation processes in the last 100 years. The main goal of the present study was the application of 210Pb, 137Cs dating techniques to estimate the recent sedimentation rates in the bay. Two sediment cores, (S and N) have been collected in 1999 using a gravity corer. The lengths of the cores were 0.93m. The cores were extruded and sliced immediately in 1.5cm intervals. Aliquots of 5g of each core sections were used for complementary analyses. The remaining parts were dried and placed in standard geometry for the determination of 210Pb and 137Cs activities, by g spectrometry with an hyper pure Germanium detector coupled with multichannel analyzer. Both core profiles show that important environmental changes have been

  1. Laser confocal microscope noise evaluation on injection compression moulded (ICM) transparent polymer Fresnel lenses

    DEFF Research Database (Denmark)

    Loaldi, D.; Calaon, Matteo; Quagliotti, Danilo

    , on an injection compression moulded (ICM) Fresnel lens, is defined. A set of two different objectives is considered, i.e. a standard series (SO), against a long working distance one (LWD); two different magnifications objectives, 50x and 100x and the use or not of a dark environment. The noise evaluation...... are measuring working distance, objective magnification and room lighting. The result confirms a strong difference of noise, using the considered objectives. The most interesting result is that the performance of SO 50x objective is better than LWD 100x....

  2. Space Photovoltaic Concentrator Using Robust Fresnel Lenses, 4-Junction Cells, Graphene Radiators, and Articulating Receivers

    Science.gov (United States)

    O'Neill, Mark; McDanal, A. J.; Brandhorst, Henry; Spence, Brian; Iqbal, Shawn; Sharps, Paul; McPheeters, Clay; Steinfeldt, Jeff; Piszczor, Michael; Myers, Matt

    2016-01-01

    At the 42nd PVSC, our team presented recent advances in our space photovoltaic concentrator technology. These advances include more robust Fresnel lenses for optical concentration, more thermally conductive graphene radiators for waste heat rejection, improved color-mixing lens technology to minimize chromatic aberration losses with 4-junction solar cells, and an articulating photovoltaic receiver enabling single-axis sun-tracking, while maintaining a sharp focal line despite large beta angles of incidence. In the past year, under a NASA Phase II SBIR program, our team has made much additional progress in the development of this new space photovoltaic concentrator technology, as described in this paper.

  3. Aplikasi Termoelektrik Generator Sebagai Sumber Energi Listrik Dengan Lensa Fresnel Sebagai Kolektor Panas Matahari

    OpenAIRE

    Simanjuntak, Jerri

    2015-01-01

    It has been designed a thermoelectric generator to produce electricity. By utilizing solar heat as the hot side of the peltier element. Fresnel Lens is used to collect sunlight towards the aluminium plate which is directly on the hot side of the peltier element. The working principle of thermoelectric generator according to the Seebeck effect, where the presence of the temperature difference between the hot side and a cold side peltier there will be a flow of current to produce a voltage.Test...

  4. Improvement of Quality of Reconstructed Images in Multi-Frame Fresnel Digital Holography

    International Nuclear Information System (INIS)

    Xiao-Wei, Lu; Jing-Zhen, Li; Hong-Yi, Chen

    2010-01-01

    A modified reconstruction algorithm to improve the quality of reconstructed images of multi-frame Fresnel digital holography is presented. When the reference beams are plane or spherical waves with azimuth encoding, by introducing two spherical wave factors, images can be reconstructed with only one time Fourier transform. In numerical simulation, this algorithm could simplify the reconstruction process and improve the signal-to-noise ratio of the reconstructed images. In single-frame reconstruction experiments, the accurate reconstructed image is obtained with this simplified algorithm

  5. Application of up-sampling and resolution scaling to Fresnel reconstruction of digital holograms.

    Science.gov (United States)

    Williams, Logan A; Nehmetallah, Georges; Aylo, Rola; Banerjee, Partha P

    2015-02-20

    Fresnel transform implementation methods using numerical preprocessing techniques are investigated in this paper. First, it is shown that up-sampling dramatically reduces the minimum reconstruction distance requirements and allows maximal signal recovery by eliminating aliasing artifacts which typically occur at distances much less than the Rayleigh range of the object. Second, zero-padding is employed to arbitrarily scale numerical resolution for the purpose of resolution matching multiple holograms, where each hologram is recorded using dissimilar geometric or illumination parameters. Such preprocessing yields numerical resolution scaling at any distance. Both techniques are extensively illustrated using experimental results.

  6. The Fresnel mode of Lorentz microscopy using a scanning transmission electron microscope

    International Nuclear Information System (INIS)

    Chapman, J.N.; Waddell, E.M.; Batson, P.E.; Ferrier, R.P.

    1979-01-01

    The most widely used method of investigating ferromagnetic films in the transmission electron microscope is the Fresnel or defocus mode of Lorentz microscopy. This may be implemented either in a fixed beam or a scanning instrument. Despite a rather inefficient utilization of electrons, several advantages accrue if the latter is used, and provided it is equipped with a field emission gun, low noise images may be obtained in acceptable recording times. To extract quantitative estimates of domain wall widths from such images it is necessary to measure accurately both instrumental and specimen parameters. Methods for this are discussed and an example of an analysis using a polycrystalline permalloy film is given. (Auth.)

  7. Fresnel: O formulador matemático da teoria ondulatória da luz

    OpenAIRE

    Bassalo, José Maria Filardo

    1988-01-01

    Neste artigo, apresentamos alguns aspectos da vida de Fresnel, engenheiro e físico francês que se notabilizou pela formulação matemática da teoria ondulatória da luz, e cujo bicentenário de nascimento transcorre neste ano de 1988. Realçamos, neste trabalho, suas principais pesquisas relacionadas com o estudo da difração, dupla-refração e reflexão da luz, nas quais utilizou a idéia revolucionária de transversalidade da onda luminosa para deduzir equações, as quais explicaram alg...

  8. Femtosecond laser-ablated Fresnel zone plate fiber probe and sensing applications

    Science.gov (United States)

    Tan, Xiaoling; Geng, Youfu; Chen, Yan; Li, Shiguo; Wang, Xinzhong

    2018-02-01

    We investigate the Fresnel zone plate (FZP) inscribed on multimode fiber endface using femtosecond laser ablation and its application in sensing. The mode transmission through fiber tips with FZP is investigated both by the beam propagation method theoretically and by measuring the beam images with a charge-coupled device camera experimentally, which show a good agreement. Such devices are tested for surface-enhanced Raman scattering (SERS) using the aqueous solution of rhodamine 6G under a Raman spectroscopy. The experimental results demonstrate that the SERS signal is enhanced benefiting from focal ability of FZP, which is a promising method for the particular biochemical spectra sensing applications.

  9. Far-field and Fresnel Liquid Crystal Geometric Phase Holograms via Direct-Write Photo-Alignment

    Directory of Open Access Journals (Sweden)

    Xiao Xiang

    2017-12-01

    Full Text Available We study computer-generated geometric-phase holograms (GPHs realized by photo-aligned liquid crystals, in both simulation and experiment. We demonstrate both far-field and Fresnel holograms capable of producing far-field and near-field images with preserved fidelity for all wavelengths. The GPHs are fabricated by patterning a photo-alignment layer (PAL using a direct-write laser scanner and coating the surface with a polymerizable liquid crystal (i.e., a reactive mesogen. We study various recording pixel sizes, down to 3 μm, that are easily recorded in the PAL. We characterize the fabricated elements and find good agreement with theory and numerical simulation. Because of the wavelength independent geometric phase, the (phase fidelity of the replay images is preserved for all wavelengths, unlike conventional dynamic phase holograms. However, governed by the diffraction equation, the size and location of a reconstructed image depends on the replay wavelength for far-field and near-field GPHs, respectively. These offer interesting opportunities for white-light holography.

  10. Flux scaling: Ultimate regime

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Flux scaling: Ultimate regime. With the Nusselt number and the mixing length scales, we get the Nusselt number and Reynolds number (w'd/ν) scalings: and or. and. scaling expected to occur at extremely high Ra Rayleigh-Benard convection. Get the ultimate regime ...

  11. Study of recent changes in sedimentation regime inside Cienfuegos Bay, Cuba using 210Pb and 137Cs as tracers

    International Nuclear Information System (INIS)

    Alonso-Hernandez, A.; Delfanti, R.; Papucci, C.; Diaz-Asencio, M.; Munoz-Caravaca, A.

    2002-01-01

    Sedimentation dynamics in the Cienfuegos Bay was investigated based on profiles and inventories of 210 Pb ex and 137 Cs in cores collected at two sites. The age of sediment layers was determined using the CRS model. Both cores show changes in sedimentation regime in the last 40 years. Since 1960-1965 sediment accumulation rates have doubled in both cells of the bay, from 0.2 to 0.4 g.cm -2 .y -1 . This change was probably one of the factors that influenced the important environmental modifications observed in the area. (author)

  12. Water regime-nitrogen fertilizer incorporation interaction: Field study on methane and nitrous oxide emissions from a rice agroecosystem in Harbin, China.

    Science.gov (United States)

    Dong, Wenjun; Guo, Jia; Xu, Lijun; Song, Zhifeng; Zhang, Jun; Tang, Ao; Zhang, Xijuan; Leng, Chunxu; Liu, Youhong; Wang, Lianmin; Wang, Lizhi; Yu, Yang; Yang, Zhongliang; Yu, Yilei; Meng, Ying; Lai, Yongcai

    2018-02-01

    Water regime and nitrogen (N) fertilizer are two important factors impacting greenhouse gases (GHG) emission from paddy field, whereas their effects have not been well studied in cold region. In this study, we conducted a two-year field experiment to study the impacts of water regime and N fertilizer on rice yields and GHG emissions in Harbin, China, a cold region located in high latitudes. Our results showed that intermittent irrigation significantly decreased methane (CH 4 ) emission compared with continuous flooding, however, the decrement was far lower than the global average level. The N 2 O emissions were very small when flooded but peaked at the beginning of the disappearance of floodwater. The N fertilizer treatments increased CH 4 emissions at low level (75kgN/ha). But both CH 4 and N 2 O emissions were uninfluenced at the levels of 150kgN/ha and 225kgN/ha. Rice yields increased under intermittent irrigation and were highest at the level of 150kgN/ha. From our results, we recommended that the intermittent irrigation and 150kgN/ha as the ideal water regime-nitrogen fertilizer incorporation for this area to achieve low GHG emissions without impacting rice yields. Copyright © 2017. Published by Elsevier B.V.

  13. High efficiency and flexible working distance digital in-line holographic microscopy based on Fresnel zone plate

    International Nuclear Information System (INIS)

    Tian, Peng; Yang, Fan; Li, Fanxing; Hu, Song; Yan, Wei; Hua, Yilei

    2017-01-01

    Traditional digital in-line holography suffers from twin-image noise problems and extremely short working distances between the object and light source. Here, we propose lensless Fourier transform digital in-line holographic microscopy based on a single optical element. A Fresnel zone plate is used to split the incident light into two parts: one is scattered along the original direction, the other is gathered at a focal point and the sample is put behind the focus. The interference fringe pattern, formed by the two beams, is recorded digitally by a CCD camera. A novel reconstruction algorithm is proposed to present the object image. The proof-of-concept experiments demonstrate that the proposed technique can eliminate the twin-image noise problem, improving the image contrast with high efficiency, and increasing the flexibility of the working distance. Furthermore, a wide field of view and no contact make it a promising tool for the study of materials science, biology and microelectronics. (paper)

  14. Numerical simulation of a Linear Fresnel Reflector Concentrator used as direct generator in a Solar-GAX cycle

    Energy Technology Data Exchange (ETDEWEB)

    Velazquez, N.; Sauceda, D.; Beltran, R. [Instituto de Ingenieria, Universidad Autonoma de Baja California, Blvd. Benito Juarez y Calle de la Normal s/n, Mexicali, Baja California 21280 (Mexico); Garcia-Valladares, O. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Privada Xochicalco s/n, Temixco, Morelos 62580 (Mexico)

    2010-03-15

    In this work a methodological analysis to design and evaluate the technical feasibility of use a Linear Fresnel Reflector Concentrator (LFRC) as generator in an advanced absorption refrigeration system (Solar-GAX cycle) has been carried out. For this purpose, a detailed one-dimensional numerical simulation of the thermal and fluid-dynamic behavior of a LFRC that solves, in a segregated manner, four subroutines: (a) fluid flow inside the receptor tube, (b) heat transfer in the receptor tube wall, (c) heat transfer in cover tube wall, and (d) solar thermal analysis in the solar concentrator has been developed. The LFRC numerical model has been validated with experimental data obtained from the technical literature; after that, a parametric study for different configurations of design has been carried out in order to obtain the highest solar concentration with the lowest thermal losses, keeping in mind both specific weather conditions and construction restrictions. The numerical result obtained demonstrates that using a LFRC as a direct generator in a Solar-GAX cycle satisfy not only the quantity and quality of the energy demanded by the advanced cooling system, it also allows to obtain higher global efficiencies of the system due to it can be operated in conditions where the maximum performance of the Solar-GAX cycle is obtained without affecting in any significant way the solar collector efficiency. (author)

  15. Numerical simulation of a Linear Fresnel Reflector Concentrator used as direct generator in a Solar-GAX cycle

    International Nuclear Information System (INIS)

    Velazquez, N.; Garcia-Valladares, O.; Sauceda, D.; Beltran, R.

    2010-01-01

    In this work a methodological analysis to design and evaluate the technical feasibility of use a Linear Fresnel Reflector Concentrator (LFRC) as generator in an advanced absorption refrigeration system (Solar-GAX cycle) has been carried out. For this purpose, a detailed one-dimensional numerical simulation of the thermal and fluid-dynamic behavior of a LFRC that solves, in a segregated manner, four subroutines: (a) fluid flow inside the receptor tube, (b) heat transfer in the receptor tube wall, (c) heat transfer in cover tube wall, and (d) solar thermal analysis in the solar concentrator has been developed. The LFRC numerical model has been validated with experimental data obtained from the technical literature; after that, a parametric study for different configurations of design has been carried out in order to obtain the highest solar concentration with the lowest thermal losses, keeping in mind both specific weather conditions and construction restrictions. The numerical result obtained demonstrates that using a LFRC as a direct generator in a Solar-GAX cycle satisfy not only the quantity and quality of the energy demanded by the advanced cooling system, it also allows to obtain higher global efficiencies of the system due to it can be operated in conditions where the maximum performance of the Solar-GAX cycle is obtained without affecting in any significant way the solar collector efficiency.

  16. Terahertz Harmonic Operation of Microwave Fresnel Zone Plate Lens and Antenna: Frequency Filtering and Space Resolution Properties

    Directory of Open Access Journals (Sweden)

    Hristo D. Hristov

    2011-01-01

    Full Text Available This paper examines the binary Fresnel zone plate (FZP lens frequency-harmonic and space-resolution focusing, and its application as a FZP lens antenna. A microwave FZP lens antenna (FZPA radiates both at design (90 GHz and terahertz (THz odd harmonic frequencies. Frequency and space domain antenna operation are studied analytically by use of the vector diffraction integral applied to a realistic printed FZPA. It is found that all harmonic gain peaks are roughly identical in form, bandwidth, and top values. At each harmonic frequency, the FZPA has a beamwidth that closely follows the Rayleigh resolution criterion. If the lens/antenna resolution is of prime importance and the small aperture efficiency is a secondary problem the microwave-design FZP lens antenna can be of great use at much higher terahertz frequencies. Important feature of the microwave FZP lens is its broader-zone construction compared to the equal in resolution terahertz-design FZP lens. Thus, unique and expensive microtechnology for the microwave FZP lens fabrication is not required. High-order harmonic operation of the FZP lens or lens antenna could find space resolution and frequency filtering applications in the terahertz and optical metrology, imaging tomography, short-range communications, spectral analysis, synchrotron facilities, and so on.

  17. Radar observations of meteor trails, and their interpretation using Fresnel holography: a new tool in meteor science

    Directory of Open Access Journals (Sweden)

    W. G. Elford

    2004-01-01

    Full Text Available A Fresnel transform technique has been developed at Adelaide to analyse radar meteor echoes detected in the transverse mode. The genesis for this technique was the study of the structure of the scattering ionization immediately behind the head of the trail, in order to deduce the degree of fragmentation of the ablating meteoroid. The technique has been remarkably successful in not only giving insight into the fragmentation of meteoroids, but also revealing other significant features of the trails including diffusion, lateral motion of the trail during formation due to wind drift, and phase of the scattered signal in the vicinity of the head of the trail. A serendipitous outcome of the analysis is the measurement of the speed and deceleration of the meteoroid producing the trail to a precision far exceeding that available from any other method applied to transverse scatter data. Examples of the outcomes of the technique applied to meteor echoes obtained with a 54MHz narrow beam radar are presented.

  18. Design and thermal performances of a scalable linear Fresnel reflector solar system

    International Nuclear Information System (INIS)

    Zhu, Yanqing; Shi, Jifu; Li, Yujian; Wang, Leilei; Huang, Qizhang; Xu, Gang

    2017-01-01

    Highlights: • A scalable linear Fresnel reflector which can supply different temperatures is proposed. • Inclination design of the mechanical structure is used to reduce the end losses. • The maximum thermal efficiency of 64% is achieved in Guangzhou. - Abstract: This paper proposes a scalable linear Fresnel reflector (SLFR) solar system. The optical mirror field which contains an array of linear plat mirrors closed to each other is designed to eliminate the inter-low shading and blocking. Scalable mechanical mirror support which can place different number of mirrors is designed to supply different temperatures. The mechanical structure can be inclined to reduce the end losses. Finally, the thermal efficiency of the SLFR with two stage mirrors is tested. After adjustment, the maximum thermal efficiency of 64% is obtained and the mean thermal efficiency is higher than that before adjustment. The results indicate that the end losses have been reduced effectively by the inclination design and excellent thermal performance can be obtained by the SLFR after adjustment.

  19. Enhancement of security using structured phase masked in optical image encryption on Fresnel transform domain

    Science.gov (United States)

    Yadav, Poonam Lata; Singh, Hukum

    2018-05-01

    To enhance the security in optical image encryption system and to protect it from the attackers, this paper proposes new digital spiral phase mask based on Fresnel Transform. In this cryptosystem the Spiral Phase Mask (SPM) used is a hybrid of Fresnel Zone Plate (FZP) and Radial Hilbert Mask (RHM) which makes the key strong and enhances the security. The different keys used for encryption and decryption purposed make the system much more secure. Proposed scheme uses various structured phase mask which increases the key space also it increases the number of parameters which makes it difficult for the attackers to exactly find the key to recover the original image. We have also used different keys for encryption and decryption purpose to make the system much more secure. The strength of the proposed cryptosystem has been analyzed by simulating on MATLAB 7.9.0(R2008a). Mean Square Errors (MSE) and Peak Signal to Noise Ratio (PSNR) are calculated for the proposed algorithm. The experimental results are provided to highlight the effectiveness and sustainability of proposed cryptosystem and to prove that the cryptosystem is secure for usage.

  20. Thermal performance of a linear Fresnel reflector solar concentrator PV/T energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Gomaa, Mohamed R. [State Engineering University of Armenia (Armenia)], E-Mail: Dmoh_elbehary@yahoo.com

    2011-07-01

    This is a report on an investigation of photovoltaic/thermal (PV/T) collectors. Solar energy conversion efficiency was increased by taking advantage of PV/T collectors and low solar concentration technologies, combined into a PV/T system operated at elevated temperature. The main novelty is the coupling of a linear Fresnel mirror reflecting concentrator with a channel PV/T collector. Concentrator PV/T collectors can function at temperatures over 100 degrees celsius, and thus thermal energy can be made to drive processes such as refrigeration, desalination and steam production. Solar system analytical thermal performance gives efficiency values over 60%. Combined electric and thermal (CET) efficiency is high. A combined electric and heat power for the linear fresnel reflector approach that employs high performance CPV technology to produce both electricity and thermal energy at low to medium temperatures is presented. A well-functioning PV/T system can be designed and constructed with low concentration and a total efficiency of nearly 80% can be attained.

  1. [System design of open-path natural gas leakage detection based on Fresnel lens].

    Science.gov (United States)

    Xia, Hui; Liu, Wen-Qing; Zhang, Yu-Jun; Kan, Rui-Feng; Cui, Yi-Ben; Wang, Min; He, Ying; Cui, Xiao-Juan; Ruan, Jun; Geng, Hui

    2009-03-01

    Based on the technology of tunable diode laser absorption spectroscopy (TDLAS) in conjunction with second harmonic wave detection, a long open-path TDLAS system using a 1.65 microm InGaAsP distributed feedback laser was developed, which is used for detecting pipeline leakage. In this system, a high cost performance Fresnel lens is used as the receiving optical system, which receives the laser-beam reflected by a solid corner cube reflector, and focuses the receiving laser-beam to the InGaAs detector. At the same time, the influences of the concentration to the fluctuation of light intensity were taken into account in the process of measurement, and were eliminated by the method of normalized light intensity. As a result, the measurement error caused by the fluctuation of light intensity was made less than 1%. The experiment of natural gas leakage detection was simulated, and the detection sensitivity is 0.1 x 10(-6) (ratio by volume) with a total path of 320 m. According to the receiving light efficiency of the optical system and the detectable minimum light intensity of the detector, the detectable maximal optical path of the system was counted to be 2 000 m. The results of experiment show that it is a feasible design to use the Fresnel lens as the receiving optical system and can satisfy the demand of the leakage detection of natural gas.

  2. From Mie to Fresnel through effective medium approximation with multipole contributions

    International Nuclear Information System (INIS)

    Malasi, Abhinav; Kalyanaraman, Ramki; Garcia, Hernando

    2014-01-01

    The Mie theory gives the exact solution to scattering from spherical particles while the Fresnel theory provides the solution to optical behavior of multilayer thin film structures. Often, the bridge between the two theories to explain the behavior of materials such as nanoparticles in a host dielectric matrix, is done by effective medium approximation (EMA) models which exclusively rely on the dipolar response of the scattering objects. Here, we present a way to capture multipole effects using EMA. The effective complex dielectric function of the composite is derived using the Clausius–Mossotti relation and the multipole coefficients of the approximate Mie theory. The optical density (OD) of the dielectric slab is then calculated using the Fresnel approach. We have applied the resulting equation to predict the particle size dependent dipole and quadrupole behavior for spherical Ag nanoparticles embedded in glass matrix. This dielectric function contains the relevant properties of EMA and at the same time predicts the multipole contributions present in the single particle Mie model. (papers)

  3. Implementation of real-time multiple reflection and Fresnel absorption of laser beam in keyhole

    International Nuclear Information System (INIS)

    Cho, Jung-Ho; Na, Suck-Joo

    2006-01-01

    A computational analysis of laser keyhole welding is achieved. The main driving force to make the molten pool as a narrow and deep keyhole is the recoil pressure induced by evaporation of the material. Also, the multiple reflection effect on the keyhole wall plays an important role in making the keyhole deeper and raising its total energy absorption rate. Multiple reflection and Fresnel absorption are implemented simultaneously with the proposed ray tracing technique in a discrete grid cell system during the simulation for every single time step. In particular, the Fresnel absorption model is chosen as an energy transfer mechanism from laser beam to workpiece. With all the governing equations including continuity, momentum and energy equation, the VOF method is adopted to trace the free surface of the molten pool. Simulation results are compared with the experimental ones to verify its validity. A pulsed Nd : YAG laser was used for keyhole welding experiments on mild steel plates of 7 mm thickness. It was observed that the generated keyhole maintains its solidified shape without any closing phenomenon both in the experiments and in the simulations

  4. Implementation of real-time multiple reflection and Fresnel absorption of laser beam in keyhole

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jung-Ho; Na, Suck-Joo [Department of Mechanical Engineering, KAIST, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2006-12-21

    A computational analysis of laser keyhole welding is achieved. The main driving force to make the molten pool as a narrow and deep keyhole is the recoil pressure induced by evaporation of the material. Also, the multiple reflection effect on the keyhole wall plays an important role in making the keyhole deeper and raising its total energy absorption rate. Multiple reflection and Fresnel absorption are implemented simultaneously with the proposed ray tracing technique in a discrete grid cell system during the simulation for every single time step. In particular, the Fresnel absorption model is chosen as an energy transfer mechanism from laser beam to workpiece. With all the governing equations including continuity, momentum and energy equation, the VOF method is adopted to trace the free surface of the molten pool. Simulation results are compared with the experimental ones to verify its validity. A pulsed Nd : YAG laser was used for keyhole welding experiments on mild steel plates of 7 mm thickness. It was observed that the generated keyhole maintains its solidified shape without any closing phenomenon both in the experiments and in the simulations.

  5. Talbot effect of the defective grating in deep Fresnel region

    Science.gov (United States)

    Teng, Shuyun; Wang, Junhong; Zhang, Wei; Cui, Yuwei

    2015-02-01

    Talbot effect of the grating with different defect is studied theoretically and experimentally in this paper. The defects of grating include the loss of the diffraction unit, the dislocation of the diffraction unit and the modulation of the unit separation. The exact diffraction distributions of three kinds of defective gratings are obtained according to the finite-difference time-domain (FDTD) method. The calculation results show the image of the missing or dislocating unit appears at the Talbot distance (as mentioned in K. Patorski Prog. Opt., 27, 1989, pp.1-108). This is the so-called self-repair ability of grating imaging. In addition, some more phenomena are discovered. The loss or the dislocation of diffraction unit causes the diffraction distortion within a certain radial angle. The regular modulation of unit separation changes the original diffraction, but the new periodicity of the diffraction distribution rebuilds. The self-imaging of grating with smaller random modulation still keeps the partial self-repair ability, and yet this characteristic depends on the modulation degree of defective grating. These diffraction phenomena of the defective gratings are explained by use of the diffraction theory of grating. The practical experiment is also performed and the experimental results confirm the theoretic predictions.

  6. Ultra-fast X-ray absorption spectroscopy for the study of matter in transient regime; Spectroscopie d'absorption ultra-rapide de rayonnement X pour l'etude de la matiere en regime transitoire

    Energy Technology Data Exchange (ETDEWEB)

    Lecherbourg, L

    2007-12-15

    In this work, we study the physics of dense matter, plasmas or solids, using X-ray absorption spectroscopy. Through the use of sources produced by laser-matter interaction, we have measured the absorption spectra of aluminum and bromine plasmas, as well as those of vanadium dioxide (VO{sub 2}). The measurement of absorption coefficients allows us to probe the dense matter and to study its properties. The experiments are carried out following the same principle: they use the same experimental set-up, called pump-probe. When the matter is dense, the absorption properties of an atom are modified by the surrounding environment. In a plasma, it is mainly the bound- bound transitions which are altered: the shapes of those spectral rays are modified. In a solid, the position of the neighbouring atoms in relation to the absorbing atom modify the structure of absorption levels (bound-free transition). The study of this structure allows us to measure the parameters of the material, and provides information such as the state of the electronic band or the interatomic gaps. The experiments carried out at the LULI have allowed us to probe plasmas in the relatively unknown regime of the Warm Dense Matter. One of the key parameters is that the plasma is characterised independently (FDI diagnostic). It allows for a better comparison of the measured absorption against a calculation made with the numerical model OPA-S. The experiments carried out at INRS have led to the realisation of an experimental system having the characteristics which allow the study of the dynamics of solids showing ultra-fast phase transition. For those experiments, we have used vanadium dioxide as a model system allowing us to test the feasibility of the method. (author)

  7. A large-scale simulation of climate change effects on flood regime - A case study for the Alabama-Coosa-Tallapoosa River Basin

    Science.gov (United States)

    Dullo, T. T.; Gangrade, S.; Marshall, R.; Islam, S. R.; Ghafoor, S. K.; Kao, S. C.; Kalyanapu, A. J.

    2017-12-01

    The damage and cost of flooding are continuously increasing due to climate change and variability, which compels the development and advance of global flood hazard models. However, due to computational expensiveness, evaluation of large-scale and high-resolution flood regime remains a challenge. The objective of this research is to use a coupled modeling framework that consists of a dynamically downscaled suite of eleven Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models, a distributed hydrologic model called DHSVM, and a computational-efficient 2-dimensional hydraulic model called Flood2D-GPU to study the impacts of climate change on flood regime in the Alabama-Coosa-Tallapoosa (ACT) River Basin. Downscaled meteorologic forcings for 40 years in the historical period (1966-2005) and 40 years in the future period (2011-2050) were used as inputs to drive the calibrated DHSVM to generate annual maximum flood hydrographs. These flood hydrographs along with 30-m resolution digital elevation and estimated surface roughness were then used by Flood2D-GPU to estimate high-resolution flood depth, velocities, duration, and regime. Preliminary results for the Conasauga river basin (an upper subbasin within ACT) indicate that seven of the eleven climate projections show an average increase of 25 km2 in flooded area (between historic and future projections). Future work will focus on illustrating the effects of climate change on flood duration and area for the entire ACT basin.

  8. Outdoor performance analysis of a 1090× point-focus Fresnel high concentrator photovoltaic/thermal system with triple-junction solar cells

    International Nuclear Information System (INIS)

    Xu, Ning; Ji, Jie; Sun, Wei; Han, Lisheng; Chen, Haifei; Jin, Zhuling

    2015-01-01

    Graphical abstract: A high concentrator photovoltaic/thermal (HCPV/T) system based on point-focus Fresnel lens has been set up in this work. The concentrator has a geometric concentration ratio of 1090× and uniform irradiation distribution can be obtained on solar cells. The system produces both electricity and heat. Performance of the system has been investigated based on the outdoor measurement in a clear day. The HCPV/T system presents an instantaneous electrical efficiency of 28% and a highest instantaneous thermal efficiency of 54%, respectively. Experimental results show that direct irradiation affects the electrical performance of the system dominantly. Fitting results of electrical performance offer simple and reliable methods to analyze the system performance. - Highlights: • A point-focus Fresnel lens photovoltaic/thermal system is proposed and studied. • The system presents an instantaneous electrical efficiency of 28%. • The system has a highest instantaneous thermal efficiency of 54%. • Direct irradiation has the dominant effect on the electrical performance. • Fitting results offer simple and reliable methods to analyze system performances. - Abstract: A high concentrator photovoltaic/thermal (HCPV/T) system based on point-focus Fresnel lens has been set up in this work. The concentrator has a geometric concentration ratio of 1090× and uniform irradiation distribution can be obtained on solar cells. The system produces both electricity and heat. Performance of the system has been investigated based on the outdoor measurement in a clear day. The HCPV/T system presents an instantaneous electrical efficiency of 28% and a highest instantaneous thermal efficiency of 54%, which means the overall efficiency of the system can be more than 80%. A mathematical model for calculating cell temperature is proposed to solve difficult measurement of cell temperature in a system. Moreover, characteristics of electrical performance under various direct

  9. R7T7-type HLW glass alteration under irradiation. Study of the residual alteration rate regime

    International Nuclear Information System (INIS)

    Rolland, Severine

    2012-01-01

    In France, fission products and minor actinides remaining after reprocessing of spent nuclear fuel are confined in a borosilicate glass matrix, named R7T7, for disposal in a geological repository. However, in these conditions, after several thousand years, water could arrive in contact with glass and be radio-lysed. In this work, we investigated the irradiation influence and especially the influence of the energy deposition on the residual glass alteration rate regime in pure water. Two types of leaching tests have been carried out. The first were performed on radioactive glass and the second on a SON68 glass (nonradioactive surrogate of R7T7 glass) under external irradiation γ. (author) [fr

  10. Statistical study of undulator radiated power by a classical detection system in the mm-wave regime

    Directory of Open Access Journals (Sweden)

    A. Eliran

    2009-05-01

    Full Text Available The statistics of FEL spontaneous emission power detected with a detector integration time much larger than the slippage time has been measured in many previous works at high frequencies. In such cases the quantum (shot noise generated in the detection process is dominant. We have measured spontaneous emission in the Israeli electrostatic accelerator FEL (EA-FEL operating in the mm-wave lengths. In this regime the detector is based on a diode rectifier for which the detector quantum noise is negligible. The measurements were repeated numerous times in order to create a sample space with sufficient data enabling evaluation of the statistical features of the radiated power. The probability density function of the radiated power was found and its moments were calculated. The results of analytical and numerical models are compared to those obtained in experimental measurements.

  11. Surface wear of TiN coated nickel tool during the injection moulding of polymer micro Fresnel lenses

    DEFF Research Database (Denmark)

    Tosello, Guido; Hansen, Hans Nørgaard; Gasparin, Stefania

    2012-01-01

    Limited tool life of nickel mould inserts represents an issue for the mass-production of polymer optics with complex micro three-dimensional geometries by injection moulding. TiN coating was applied to a nickel insert for the injection moulding of polycarbonate micro Fresnel lenses. Surface wear...

  12. Energy performance of a concentrated photovoltaic energy system with static linear Fresnel lenses integrated in a greenhouse

    NARCIS (Netherlands)

    B.A.J. van Tuijl; Piet Sonneveld; J. Campen; Gert-Jan Swinkels; H.J.J. Janssen; G.P.A Bot

    2011-01-01

    A new type of greenhouse with linear Fresnel lenses in the cover performing as a concentrated photovoltaic (CPV) system is presented. The CPV system retains all direct solar radiation, while diffuse solar radiation passes through and enters into the greenhouse cultivation system. The removal of all

  13. Micro-fresnel structures for microscopy of laser generated bright x-ray sources

    International Nuclear Information System (INIS)

    Ceglio, N.M.; Shavers, D.C.; Flanders, D.C.; Smith, H.I.

    1979-01-01

    A brief parametric survey of the x-ray characteristics of a gold micro-disk irradiated at 3 x 10 14 watt/cm 2 by a 1 nsec Nd-glass laser pulse has been provided as an example of a laser generated bright x-ray source. It was shown that a simple phenomenological model of the laser generated x-ray source as a microscopic equilibrium plasma radiating as a blackbody for a finite time determined by its hydrodynamic disassembly and radiation losses, serves to provide an adequate approximation to the x-ray characteristics of such sources. The current state of x-ray microscopy within the LLL laser fusion program was briefly reviewed. Kirpatrick--Baez grazing incidence reflection x-ray microscopes are being used to provide 3 to 5 μm resolution, broadband images (ΔE/E approx. 0.3) over a spectral range from .6 keV to 3.5 keV. Zone Plate Coded Imaging is used to provide 5 to 10 μm resolution, broadband (ΔE/E approx. 0.5) images over a spectral range from 3 keV to 50 keV. Efficient x-ray lensing elements with anticipated submicron resolution are being developed for narrowband (ΔE/E approx. 10 -2 ) imaging applications over a spectral range .1 keV to 8 keV. The x-ray lens design is that of a transmission blazed Fresnel phase plate. Micro--Fresnel zone plates with 3200 A minimum linewidth have been fabricated and preliminary resolution tests begun. The first resolution test pattern, having minimum linewidth of 2.5 μm, was imaged in lambda = 8.34 A light with no difficulty. Newer test patterns with submicron minimum line are being prepared for the next stage of resolution testing. An off-axis Fresnel zone plate with 1600 A minimum linewidth is presently being fabricated for use as an imaging spectrometer in order to provide spatially separated, chromatically distinct images of characteristic line emissions from laser fusion targets

  14. An Experimental and analytical study on the bubble-to-slug flow regime transition based on the void wave instability

    International Nuclear Information System (INIS)

    Song, Chul Hwa

    1995-02-01

    An experimental and analytical work is performed to investigate the relation between the developing phenomena in bubble flow and the propagation phenomena of void waves. For this purpose, the structural developments in bubble flow and the propagation property of void waves are measured over a broad range of flow conditions including the bubble-to-slug flow regime transition (BSFRT) region. And a linear stability analysis is performed, based on the two-fluid model, to establish the analytical model on the wave propagation parameters, and the predictability of the model is validated by comparing analytical results with experimental observations. In the experimental work, an impedance void meter is developed to measure the void fraction, and a series of test are performed by varying the bubble size in order to investigate the bubble size effect on the bubble flow structures for various flow conditions. Statistical signal processing techniques are applied to void signals in order to objectively identify the changing modes of bubble flow structures and to estimate the wave propagation properties. The impedance void meter developed in this study showed very good temporal and spatial resolutions enough to identify the developing phenomena in bubble flow structures and to investigate the void wave propagations, and the void distribution effect could be minimized by electrically shielding the guard electrodes. It was also designed so that the inherent errors due to the phase shifts between channels be negligible. Various features occurred in the transitional process of bubble flow could be objectively identified by introducing some statistical parameters evaluated from void signals. Two distinct modes of structural development in bubble flow were observed in the transitional process, and they are found to be much influenced by the initial bubble size. And the mechanism to govern BSFRT could be characterized by two ways depending on the developing modes of bubble flow

  15. Simulation model of a new solar laser system of Fresnel lens according to real observed solar radiation data in

    Directory of Open Access Journals (Sweden)

    Yasser A. Abdel-Hadi

    2015-12-01

    Full Text Available A new simulation model of a new solar pumped laser system was tested to be run in Helwan in Egypt (latitude φ = 29°52′N, longitude λ = 31°21′E and elevation = 141 m as an example of an industrial polluted area. The system is based on concentrating the solar radiation using a Fresnel lens on a laser head fixed on a mount tracking the sun during the day and powered by a DC battery. Two cases of this model are tested; the first one is the model consisting of a Fresnel lens and a two-dimensional Compound Parabolic Concentrator (CPC, while the other is the model consisting of a Fresnel lens and a three-dimensional Compound Parabolic Concentrator (CPC. The model is fed by real actual solar radiation data taken in Helwan Solar Radiation Station at NRIAG in the various seasons in order to know the laser power got from such a system in those conditions. For the system of Fresnel lens and 2D-CPC, an average laser output power of 1.27 W in Winter, 2 W in Spring, 5 W in Summer and 4.68 W in Autumn respectively can be obtained. Accordingly, the annual average output power for this system is 3.24 W. For the system of Fresnel lens and 3D-CPC, an average laser output power of 3.28 W in Winter, 3.55 W in Spring, 7.56 W in Summer and 7.13 W in Autumn respectively can be obtained. Accordingly, the annual average output power for this system is 5.38 W.

  16. 'CANDLE' burnup regime after LWR regime

    International Nuclear Information System (INIS)

    Sekimoto, Hiroshi; Nagata, Akito

    2008-01-01

    CANDLE (Constant Axial shape of Neutron flux, nuclide densities and power shape During Life of Energy producing reactor) burnup strategy can derive many merits. From safety point of view, the change of excess reactivity along burnup is theoretically zero, and the core characteristics, such as power feedback coefficients and power peaking factor, are not changed along burnup. Application of this burnup strategy to neutron rich fast reactors makes excellent performances. Only natural or depleted uranium is required for the replacing fuels. About 40% of natural or depleted uranium undergoes fission without the conventional reprocessing and enrichment. If the LWR produced energy of X Joules, the CANDLE reactor can produce about 50X Joules from the depleted uranium left at the enrichment facility for the LWR fuel. If we can say LWRs have produced energy sufficient for full 20 years, we can produce the energy for 1000 years by using the CANDLE reactors with depleted uranium. We need not mine any uranium ore, and do not need reprocessing facility. The burnup of spent fuel becomes 10 times. Therefore, the spent fuel amount per produced energy is also reduced to one-tenth. The details of the scenario of CANDLE burnup regime after LWR regime will be presented at the symposium. (author)

  17. Multiple Reflections and Fresnel Absorption of Gaussian Laser Beam in an Actual 3D Keyhole during Deep-Penetration Laser Welding

    Directory of Open Access Journals (Sweden)

    Xiangzhong Jin

    2012-01-01

    Full Text Available In deep penetration laser welding, a keyhole is formed in the material. Based on an experimentally obtained bending keyhole from low- and medium-speed laser penetration welding of glass, the keyhole profiles in both the symmetric plane are determined by polynomial fitting. Then, a 3D bending keyhole is reconstructed under the assumption of circular cross-section of the keyhole at each keyhole depth. In this paper, the behavior of focused Gaussian laser beam in the keyhole is analyzed by tracing a ray of light using Gaussian optics theory, the Fresnel absorption and multiple reflections in the keyhole are systematically studied, and the laser intensities absorbed on the keyhole walls are calculated. Finally, the formation mechanism of the keyhole is deduced.

  18. Designing Fresnel microlenses for focusing astigmatic multi-Gaussian beams by using fractional order Fourier transforms

    International Nuclear Information System (INIS)

    Patino, A; Durand, P-E; Fogret, E; Pellat-Finet, P

    2011-01-01

    According to a scalar theory of diffraction, light propagation can be expressed by two-dimensional fractional order Fourier transforms. Since the fractional Fourier transform of a chirp function is a Dirac distribution, focusing a light beam is optically achieved by using a diffractive screen whose transmission function is a two-dimensional chirp function. This property is applied to designing Fresnel microlenses, and the orders of the involved Fourier fractional transforms depend on diffraction distances as well as on emitter and receiver radii of curvature. If the emitter is astigmatic (with two principal radii of curvature), the diffraction phenomenon involves two one-dimensional fractional Fourier transforms whose orders are different. This degree of freedom allows us to design microlenses that can focus astigmatic Gaussian beams, as produced by a line-shaped laser diode source.

  19. Development of Fresnel-based Concentrated Photovoltaic (CPV System with Uniform Irradiance

    Directory of Open Access Journals (Sweden)

    Irfan Ullah

    2014-12-01

    Full Text Available Different designs have been presented to achieve high concentration and uniformity for the concentrated photovoltaic (CPV system. Most of the designs have issues of low efficiency in terms of irradiance uniformity. To this end, we present a design methodology to increase irradiance uniformity over solar cell. The system consists of an eight-fold Fresnel lens as a primary optical element (POE and an optical lens, which consists of eight parts, as a secondary optical element (SOE. Sunlight is focused through the POE and then light is spread over cell through the SOE. In the design, maximum sunlight is passed over cell by minimizing losses. Results have shown that the proposed CPV design gives good irradiance uniformity. The concentration module based on this novel design is a promising option for the development of a cost-effective photovoltaic solar energy generation.

  20. Evaluation of different operating strategies to integrate storage in a linear Fresnel ORC power plant

    Science.gov (United States)

    Zoschke, Theda; Seubert, Bernhard; Fluri, Thomas

    2017-06-01

    An existing linear Fresnel power plant with ORC process located in Ben Guerir, Morocco, is retrofitted with a thermal energy storage system and additional collector loops. Two different plant configurations are investigated in this paper. In the first configuration two separate solar fields are built and only the minor one can charge the storage. In the second configuration, there is only one large solar field which offers more flexibility. Two different control strategies are assessed by comparing simulation results. It shows that the simulations of the systems with two solar fields results in higher energy yields throughout the year, but the power production of the system with one solar field is much more flexible and demand oriented. Also it offers great potential for improvement when it comes to weather forecasting.

  1. Generation of Binary Off-axis Digital Fresnel Hologram with Enhanced Quality

    Directory of Open Access Journals (Sweden)

    Peter Wai Ming Tsang

    2015-06-01

    Full Text Available The emergence of high resolution printer and digital micromirror device (DMD has enabled real, off-axis holograms to be printed, or projected onto a screen. As most printers and DMD can only reproduce binary dots, the pixels in a hologram have to be truncated to 2 levels. However, direct binarizing a hologram will lead to severe degradation on its reconstructed image. In this paper, a method for generating binary off-axis digital Fresnel hologram is reported. A hologram generated with the proposed method is referred to as the "Enhanced Sampled Binary Hologram" (ESBH. The reconstructed image of the ESBH is superior in visual quality as compare with the one obtained with existing technique, and also resistant to noise contamination.

  2. Optical image encryption using fresnel zone plate mask based on fast walsh hadamard transform

    Science.gov (United States)

    Khurana, Mehak; Singh, Hukum

    2018-05-01

    A new symmetric encryption technique using Fresnel Zone Plate (FZP) based on Fast Walsh Hadamard Transform (FWHT) is proposed for security enhancement. In this technique, bits of plain image is randomized by shuffling the bits randomly. The obtained scrambled image is then masked with FZP using symmetric encryption in FWHT domain to obtain final encrypted image. FWHT has been used in the cryptosystem so as to protect image data from the quantization error and for reconstructing the image perfectly. The FZP used in proposed scheme increases the key space and makes it robust to many traditional attacks. The effectiveness and robustness of the proposed cryptosystem has been analyzed on the basis of various parameters by simulating on MATLAB 8.1.0 (R2012b). The experimental results are provided to highlight suitability of the proposed cryptosystem and prove that the system is secure.

  3. Generalizing, optimizing, and inventing numerical algorithms for the fractional Fourier, Fresnel, and linear canonical transforms

    Science.gov (United States)

    Hennelly, Bryan M.; Sheridan, John T.

    2005-05-01

    By use of matrix-based techniques it is shown how the space-bandwidth product (SBP) of a signal, as indicated by the location of the signal energy in the Wigner distribution function, can be tracked through any quadratic-phase optical system whose operation is described by the linear canonical transform. Then, applying the regular uniform sampling criteria imposed by the SBP and linking the criteria explicitly to a decomposition of the optical matrix of the system, it is shown how numerical algorithms (employing interpolation and decimation), which exhibit both invertibility and additivity, can be implemented. Algorithms appearing in the literature for a variety of transforms (Fresnel, fractional Fourier) are shown to be special cases of our general approach. The method is shown to allow the existing algorithms to be optimized and is also shown to permit the invention of many new algorithms.

  4. Novel Scanning Lens Instrument for Evaluating Fresnel Lens Performance: Equipment Development and Initial Results (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Herrero, R.; Miller, D. C.; Kurtz, S. R.; Anton, I.; Sala, G.

    2013-07-01

    A system dedicated to the optical transmittance characterization of Fresnel lenses has been developed at NREL, in collaboration with the UPM. The system quantifies the optical efficiency of the lens by generating a performance map. The shape of the focused spot may also be analyzed to understand change in the lens performance. The primary instrument components (lasers and CCD detector) have been characterized to confirm their capability for performing optical transmittance measurements. Measurements performed on SoG and PMMA lenses subject to a variety of indoor conditions (e.g., UV and damp heat) identified differences in the optical efficiency of the evaluated lenses, demonstrating the ability of the Scanning Lens Instrument (SLI) to distinguish between the aged lenses.

  5. Development of a high-resolution electron-beam profile monitor using Fresnel zone plates

    International Nuclear Information System (INIS)

    Nakamura, Norio; Sakai, Hiroshi; Muto, Toshiya; Hayano, Hitoshi

    2004-01-01

    We present a high-resolution and real-time beam profile monitor using Fresnel zone plates (FZPs) developed in the KEK-ATF damping ring. The monitor system has an X-ray imaging optics with two FZPs. In this monitor, the synchrotron radiation from the electron beam at the bending magnet is monochromatized by a crystal monochromator and the transverse electron beam image is twenty-times magnified by the two FZPs and detected on an X-ray CCD camera. The expected spatial resolution for the selected photon energy of 3.235 keV is less than 1 μm. With the beam profile monitor, we succeeded in obtaining a clear electron-beam image and measuring the extremely small beam size less than 10 μm. It is greatly expected that the beam profile monitor will be used in high-brilliance light sources and low-emittance accelerators. (author)

  6. Contribution to the determination of nuclear friction by studying the de-excitation of nuclei in the transient regime

    International Nuclear Information System (INIS)

    Hassani, S.

    1985-01-01

    An old idea of Kramers is to consider nuclear fission as a diffusion process in phase space corresponding to the collective variable of fission. The fission width is taken as an escape rate of the system over the barrier potential. The evolution of the distribution of this collective variable and its conjugate is governed by a Fokker-Planck equation. In a quasistationary treatment Kramers obtained a fission rate which differs from the result given by the transition state method by a friction dependent factor. The non quasistationary solution of the Fokker-Planck equation allows to obtain an escape rate that presents a transient regime: from zero it grows and reaches asymptotically the Kramers' value. This time-dependent fission width is included in a formalism that describes the deexcitation of the compound nucleus in order to calculate the neutron multiplicities in competition with fission. A sensitive friction-dependence of the multiplicities is obtained. Using this formalism and comparing the results with data of a recent experiment gives a good agreement; resolving the disagreement between data and the usual statistical model at high energy. A range of values of the friction coefficient is deduced [fr

  7. Rainfall and runoff regime trends in mountain catchments (Case study area: the upper Hron River basin, Slovakia

    Directory of Open Access Journals (Sweden)

    Blahušiaková Andrea

    2015-09-01

    Full Text Available This paper presents an analysis of trends and causes of changes of selected hydroclimatic variables influencing the runoff regime in the upper Hron River basin (Slovakia. Different methods for identifying trends in data series are evaluated and include: simple mass curve analysis, linear regression, frequency analysis of flood events, use of the Indicators of Hydrological Alteration software, and the Mann-Kendall test. Analyses are performed for data from two periods (1931-2010 and 1961-2010. The changes in runoff are significant, especially in terms of lower QMax and 75 percentile values. This fact is also confirmed by the lower frequency and extremity of flood events. The 1980s are considered a turning point in the development of all hydroclimatic variables. The Mann-Kendall test shows a significant decrease in runoff in the winter period. The main causes of runoff decline are: the considerable increase in air temperature, the decrease in snow cover depth and changes in seasonal distribution of precipitation amounts.

  8. Intrastate Dynamics in the Context of Hegemonic Decline: A Case Study of China’s Arms Transfer Regime

    Directory of Open Access Journals (Sweden)

    Zhifan Luo

    2017-02-01

    Full Text Available The decline of a hegemon can create openings for lesser powers to expand their influence in the world-system. Is this what China is currently attempting to do? This paper contributes to this on-going debate by examining China’s arms transfer activities from a historical perspective. Using data from the Stockholm International Peace Research Institute arms transfer database and the World Military Expenditures and Arms Transfers database, I argue that the Chinese arms transfer regime has evolved through three phases. In Phase One, China used gifts of arms to compete with the Soviet Union and to expand influence among Third World countries. In Phase Two, China used arms exports mainly to assist national developmental projects. Only evidence in Phase Three supports the emergence of a global strategy that attempts to extend China’s economic, political, and possibly military outreach. This paper suggests that though China has not yet become a contender for world hegemony as Arrighi argues (2007, China has formulated a globally-focused agenda which, in the medium-term, could extend its influence in regions where U.S. domination is relatively weak.

  9. Optical-CT 3D Dosimetry Using Fresnel Lenses with Minimal Refractive-Index Matching Fluid.

    Directory of Open Access Journals (Sweden)

    Steven Bache

    Full Text Available Telecentric optical computed tomography (optical-CT is a state-of-the-art method for visualizing and quantifying 3-dimensional dose distributions in radiochromic dosimeters. In this work a prototype telecentric system (DFOS-Duke Fresnel Optical-CT Scanner is evaluated which incorporates two substantial design changes: the use of Fresnel lenses (reducing lens costs from $10-30K t0 $1-3K and the use of a 'solid tank' (which reduces noise, and the volume of refractively matched fluid from 1 ltr to 10 cc. The efficacy of DFOS was evaluated by direct comparison against commissioned scanners in our lab. Measured dose distributions from all systems were compared against the predicted dose distributions from a commissioned treatment planning system (TPS. Three treatment plans were investigated including a simple four-field box treatment, a multiple small field delivery, and a complex IMRT treatment. Dosimeters were imaged within 2 h post irradiation, using consistent scanning techniques (360 projections acquired at 1 degree intervals, reconstruction at 2mm. DFOS efficacy was evaluated through inspection of dose line-profiles, and 2D and 3D dose and gamma maps. DFOS/TPS gamma pass rates with 3%/3mm dose difference/distance-to-agreement criteria ranged from 89.3% to 92.2%, compared to from 95.6% to 99.0% obtained with the commissioned system. The 3D gamma pass rate between the commissioned system and DFOS was 98.2%. The typical noise rates in DFOS reconstructions were up to 3%, compared to under 2% for the commissioned system. In conclusion, while the introduction of a solid tank proved advantageous with regards to cost and convenience, further work is required to improve the image quality and dose reconstruction accuracy of the new DFOS optical-CT system.

  10. Arctic circulation regimes.

    Science.gov (United States)

    Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L

    2015-10-13

    Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability. © 2015 The Authors.

  11. THE INFLUENCED FLOW REGIMES

    Directory of Open Access Journals (Sweden)

    Gavril PANDI

    2011-03-01

    Full Text Available The influenced flow regimes. The presence and activities ofhumanity influences the uniform environmental system, and in this context, therivers water resources. In concordance with this, the natural runoff regime suffersbigger and deeper changes. The nature of these changes depending on the type anddegree of water uses. The multitude of the use cause different types of influence,whit different quantitative aspects. In the same time, the influences havequalitative connotations, too, regarding to the modifications of the yearly watervolume runoff. So the natural runoff regime is modified. After analyzing thedistribution laws of the monthly runoff, there have been differenced four types ofinfluenced runoff regimes. In the excess type the influenced runoff is bigger thanthe natural, continuously in the whole year. The deficient type is characterized byinverse rapports like the first type, in the whole year. In the sinusoidal type, theinfluenced runoff is smaller than the natural in the period when the water isretained in the lake reservoirs, and in the depletion period the situation inverts. Atthe irregular type the ratio between influenced and natural runoff is changeable ina random meaner monthly. The recognition of the influenced regime and the gradeof influence are necessary in the evaluation and analysis of the usable hydrologicalriver resources, in the flood defence activities, in the complex scheme of thehydrographic basins, in the environment design and so on.

  12. The study of the kinetics of drying food raw material of plant origin in the active hydrodynamic regimes and development of dryer engineering calculation methods

    Directory of Open Access Journals (Sweden)

    A. N. Ostrikov

    2015-01-01

    Full Text Available Consumer properties of food raw material formed during the heat treatment. New physical, flavoring and aromatic properties of the products of plant origin, formed during drying due to substantial changes in the composition of the raw materia l occurring as a result of biochemical reactions. In the production of dried and roasted products is very important to follow the parameters that contribute to the passage of biochemical processes aimed at creating a product with high nutritional qualities, strong aroma and pleasant taste. We studied the basic kinetics of the drying process of food raw material (in terms of artichoke in a dense interspersed layer, which formed the basis for the rational choice of the drying regime with due consideration of changes in the moisture content of the product are studied. The nature of the effect of the dried product movement hydrodynamic conditions on a layer height and intensity of drying is established. As a result of food raw material drying process kinetics analysis (in terms of artichoke multistep drying regimes were chosen. Analysis of the artichoke particles drying by air, air-steam mixture and superheated steam intensity showed the presence of two parts: the horizontal one and gradually diminishing one. Kinetic laws of the artichoke drying process in a dense interspersed layer were the basis of engineering calculation of dryer with a transporting body in the form of a "traveling wave". Application of the dryer with the transporting body in the form of a "traveling wave" for food raw material drying allow to achieve uniform drying of the product due to the use of soft, gentle regimes of oversleeping while preserving to the utmost particles of the product; to improve the quality of the finished product through the use of interspersed layer that reduces clumping of product to be dried.

  13. A Study of Electrocyclic Reactions in a Molecular Junction: Mechanistic and Energetic Requirements for Switching in the Coulomb Blockade Regime.

    Science.gov (United States)

    Olsen, Stine T; Brøndsted Nielsen, Mogens; Hansen, Thorsten; Ratner, Mark A; Mikkelsen, Kurt V

    2017-06-20

    Molecular photoswitches incorporated in molecular junctions yield the possibility of light-controlled switching of conductance due to the electronic difference of the photoisomers. Another isomerization mechanism, dark photoswitching, promoted by a voltage stimulus rather than by light, can be operative in the Coulomb blockade regime for a specific charge state of the molecule. Here we elucidate theoretically the mechanistic and thermodynamic restrictions for this dark photoswitching for donor-acceptor substituted 4n and 4n+2 π-electron open-chain oligoenes (1,3-butadiene and 1,3,5-hexatriene) by considering the molecular energies and orbitals of the molecules placed in a junction. For an electrocyclic ring closure reaction to occur for these compounds, we put forward two requirements: a) the closed stereoisomer (cis or trans form) must be of lower energy than the open form, and b) the reaction pathway must be in accordance to the orbital symmetry rules expressed by the Woodward-Hoffmann rules (when the electrodes do not significantly alter the molecular orbital appearances). We find these two requirements to be valid for the dianion of (1E,3Z,5E)-hexa-1,3,5-triene-1,6-diamine, and the Coulomb blockade diamonds were therefore modeled for this compound to elucidate how a dark photoswitching event would manifest itself in the stability plot. From this modeling of conductance as a function of gate and bias potentials, we predict a collapse in Coulomb diamond size, that is, a decrease in the height of the island of zero conductance. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Study on lower hybrid current drive efficiency at high density towards long-pulse regimes in Experimental Advanced Superconducting Tokamak

    International Nuclear Information System (INIS)

    Li, M. H.; Ding, B. J.; Zhang, J. Z.; Gan, K. F.; Wang, H. Q.; Zhang, L.; Wei, W.; Li, Y. C.; Wu, Z. G.; Ma, W. D.; Jia, H.; Chen, M.; Yang, Y.; Feng, J. Q.; Wang, M.; Xu, H. D.; Shan, J. F.; Liu, F. K.; Peysson, Y.

    2014-01-01

    Significant progress on both L- and H-mode long-pulse discharges has been made recently in Experimental Advanced Superconducting Tokamak (EAST) with lower hybrid current drive (LHCD) [J. Li et al., Nature Phys. 9, 817 (2013) And B. N. Wan et al., Nucl. Fusion 53, 104006 (2013).]. In this paper, LHCD experiments at high density in L-mode plasmas have been investigated in order to explore possible methods of improving current drive (CD) efficiency, thus to extend the operational space in long-pulse and high performance plasma regime. It is observed that the normalized bremsstrahlung emission falls much more steeply than 1/n e-av (line-averaged density) above n e-av  = 2.2 × 10 19  m −3 indicating anomalous loss of CD efficiency. A large broadening of the operating line frequency (f = 2.45 GHz), measured by a radio frequency (RF) probe located outside the EAST vacuum vessel, is generally observed during high density cases, which is found to be one of the physical mechanisms resulting in the unfavorable CD efficiency. Collisional absorption of lower hybrid wave in the scrape off layer (SOL) may be another cause, but this assertion needs more experimental evidence and numerical analysis. It is found that plasmas with strong lithiation can improve CD efficiency largely, which should be benefited from the changes of edge parameters. In addition, several possible methods are proposed to recover good efficiency in future experiments for EAST

  15. Computational study of collisions between O(3P) and NO(2Π) at temperatures relevant to the hypersonic flight regime

    International Nuclear Information System (INIS)

    Castro-Palacio, Juan Carlos; Nagy, Tibor; Meuwly, Markus; Bemish, Raymond J.

    2014-01-01

    Reactions involving N and O atoms dominate the energetics of the reactive air flow around spacecraft when reentering the atmosphere in the hypersonic flight regime. For this reason, the thermal rate coefficients for reactive processes involving O( 3 P) and NO( 2 Π) are relevant over a wide range of temperatures. For this purpose, a potential energy surface (PES) for the ground state of the NO 2 molecule is constructed based on high-level ab initio calculations. These ab initio energies are represented using the reproducible kernel Hilbert space method and Legendre polynomials. The global PES of NO 2 in the ground state is constructed by smoothly connecting the surfaces of the grids of various channels around the equilibrium NO 2 geometry by a distance-dependent weighting function. The rate coefficients were calculated using Monte Carlo integration. The results indicate that at high temperatures only the lowest A-symmetry PES is relevant. At the highest temperatures investigated (20 000 K), the rate coefficient for the “O1O2+N” channel becomes comparable (to within a factor of around three) to the rate coefficient of the oxygen exchange reaction. A state resolved analysis shows that the smaller the vibrational quantum number of NO in the reactants, the higher the relative translational energy required to open it and conversely with higher vibrational quantum number, less translational energy is required. This is in accordance with Polanyi's rules. However, the oxygen exchange channel (NO2+O1) is accessible at any collision energy. Finally, this work introduces an efficient computational protocol for the investigation of three-atom collisions in general

  16. Computational study of collisions between O(3P) and NO(2Π) at temperatures relevant to the hypersonic flight regime.

    Science.gov (United States)

    Castro-Palacio, Juan Carlos; Nagy, Tibor; Bemish, Raymond J; Meuwly, Markus

    2014-10-28

    Reactions involving N and O atoms dominate the energetics of the reactive air flow around spacecraft when reentering the atmosphere in the hypersonic flight regime. For this reason, the thermal rate coefficients for reactive processes involving O((3)P) and NO((2)Π) are relevant over a wide range of temperatures. For this purpose, a potential energy surface (PES) for the ground state of the NO2 molecule is constructed based on high-level ab initio calculations. These ab initio energies are represented using the reproducible kernel Hilbert space method and Legendre polynomials. The global PES of NO2 in the ground state is constructed by smoothly connecting the surfaces of the grids of various channels around the equilibrium NO2 geometry by a distance-dependent weighting function. The rate coefficients were calculated using Monte Carlo integration. The results indicate that at high temperatures only the lowest A-symmetry PES is relevant. At the highest temperatures investigated (20,000 K), the rate coefficient for the "O1O2+N" channel becomes comparable (to within a factor of around three) to the rate coefficient of the oxygen exchange reaction. A state resolved analysis shows that the smaller the vibrational quantum number of NO in the reactants, the higher the relative translational energy required to open it and conversely with higher vibrational quantum number, less translational energy is required. This is in accordance with Polanyi's rules. However, the oxygen exchange channel (NO2+O1) is accessible at any collision energy. Finally, this work introduces an efficient computational protocol for the investigation of three-atom collisions in general.

  17. Study of laser-induced damage on the exit surface of silica components in the nanosecond regime in a multiple wavelengths configuration

    International Nuclear Information System (INIS)

    Chambonneau, Maxime

    2014-01-01

    In this thesis, laser-induced damage phenomenon on the surface of fused silica components is investigated in the nanosecond regime. This phenomenon consists in an irreversible modification of the material. In the nanosecond regime, laser damage is tightly correlated to the presence of non-detectable precursor defects which are a consequence of the synthesis and the polishing of the components. In this thesis, we investigate laser damage in a multiple wavelengths configuration. In order to better understand this phenomenon in these conditions of irradiation, three studies are conducted. The first one focuses on damage initiation. The results obtained in the single wavelength configurations highlight a coupling in the multiple wavelengths one. A comparison between the experiments and a model developed during this thesis enables us to improve the knowledge of the fundamental processes involved during this damage phase. Then, we show that post mortem characterizations of damage morphology coupled to an accurate metrology allow us to understand both the nature and also the chronology of the physical mechanisms involved during damage formation. The proposed theoretical scenario is confirmed through various experiments. Finally, we study damage growth in both the single and the multiple wavelengths cases. Once again, this last configuration highlights a coupling between the wavelengths. We show the necessity to account for the spatial characteristics of the laser beams during a growth session. (author) [fr

  18. Cargo liability regimes

    Science.gov (United States)

    2001-01-01

    There are at present at least three international regimes of maritime cargo liability in force in different countries of the world - the original Hague rules (1924), the updated version known as the Hague-Visby rules (1968, further amended 1979), and...

  19. Trust in regulatory regimes

    NARCIS (Netherlands)

    Six, Frédérique; Verhoest, Koen

    2017-01-01

    Within political and administrative sciences generally, trust as a concept is contested, especially in the field of regulatory governance. This groundbreaking book is the first to systematically explore the role and dynamics of trust within regulatory regimes. Conceptualizing, mapping and analyzing

  20. East Asian welfare regime

    DEFF Research Database (Denmark)

    Abrahamson, Peter

    2017-01-01

    The paper asks if East Asian welfare regimes are still productivist and Confucian? And, have they developed public care policies? The literature is split on the first question but (mostly) confirmative on the second. Care has to a large, but insufficient extent, been rolled out in the region...

  1. An equation of mean velocity of flow in non uniform regime, its relationship with the dispersion phenomenon as time function and its application to study of water quality

    International Nuclear Information System (INIS)

    Constain Aragon, A.; Lemos Ruiz, R.

    2011-01-01

    It is very well known the basic equation of hydraulics discovered by Antoine de Chezy in 1769, which relates in a quadratic from the mean velocity of flow with the slope of energy line and the hydraulic radius, in a uniform regime. This equation has been the central axis of development of hydro metrics as science that faces the huge challenges of penetrating the knowledge of earths streams every time more contaminated. In virtue of that, its mathematical structure and the relationship with other related formulas have been carefully examined, despite the limitation due to constancy of velocity. Starting from chemical considerations rather than dynamic ones as was used to obtain chezys relationship it is possible to establish a second equation for mean velocity of fluid in a non uniform regime that corresponds to averaged movement of a solute poured to steam. This equation will go to relate in an accurate way several aspects hydraulics and mass transport, sight as a single thing, allowing a vital tool for a depth study of water contaminations. to arrive this equation it was reviewed the foundations of mass transport theory in flows, stating a time dependent nature for coefficient currently used in describing dispersion phenomena allowing to interpret properly certain inconsistencies detected long time ago in this theory. It is presented the detailed results of application of this new approach to a small steam and a larger river in Colombia. (Author) 23 refs.

  2. International Food Regime

    Directory of Open Access Journals (Sweden)

    A. V. Malov

    2018-01-01

    Full Text Available The review article reveals the content of the concept of Food Regime, which is little-known in the Russian academic reference. The author monitored and codified the semantic dynamic of the terminological unit from its original interpretations to modern formulations based on the retrospective analysis. The rehabilitation of the academic merits of D. Puchala and R. Hopkins — authors who used the concept Food Regime for a few years before its universally recognized origin and official scientific debut, was accomplished with help of historical and comparative methods. The author implemented the method of ascension from the abstract to the concrete to demonstrating the classification of Food Regimes compiled on the basis of geopolitical interests in the sphere of international production, consumption, and distribution of foodstuffs. The characteristic features of historically formed Food Regime were described in the chronological order, as well as modern tendencies possessing reformist potential were identified. In particular, it has been established that the idea of Food Sovereignty (which is an alternative to the modern Corporate Food Regime is the subject for acute academic disputes. The discussion between P. McMichael P. and H. Bernstein devoted to the “peasant question” — mobilization frame of the Food Sovereignty strategy was analyzed using the secondary data processing method. Due to the critical analysis, the author comes to the conclusion that it is necessary to follow the principles of the Food Sovereignty strategy to prevent the catastrophic prospects associated with ecosystem degradation, accelerated erosion of soils, the complete disappearance of biodiversity and corporate autoc racy successfully. The author is convinced that the idea of Food Sovereignty can ward off energetic liberalization of nature, intensive privatization of life and rapid monetization of unconditioned human reflexes.

  3. A Microwave Holographic Procedure for Large Symmetric Reflector Antennas Using a Fresnel-Zone Field Data Processing

    Directory of Open Access Journals (Sweden)

    Giuseppe Mazzarella

    2012-01-01

    Full Text Available In this paper we propose a new holographic procedure for the diagnostic of large reflector antennas, based on the direct use of the Fresnel-field pattern. The relation leading from the Fresnel field to the current on the reflector surface is formulated in the least-squares sense as a discrete data inverse problem and then regularized by using a singular value decomposition approach. A detailed theoretical analysis of the problem and full assessment of the presented technique are provided. Simulations are carried out by using the radiative near-field pattern generated with a commercial software. Results show good accuracy and robustness to noise for the retrieval of the panel-to-panel misalignment of a reflector antenna.

  4. First light of an external occulter testbed at flight Fresnel numbers

    Science.gov (United States)

    Kim, Yunjong; Sirbu, Dan; Hu, Mia; Kasdin, Jeremy; Vanderbei, Robert J.; Harness, Anthony; Shaklan, Stuart

    2017-01-01

    Many approaches have been suggested over the last couple of decades for imaging Earth-like planets. One of the main candidates for creating high-contrast for future Earth-like planets detection is an external occulter. The external occulter is a spacecraft flown along the line-of-sight of a space telescope to suppress starlight and enable high-contrast direct imaging of exoplanets. The occulter is typically tens of meters in diameter and the separation from the telescope is of the order of tens of thousands of kilometers. Optical testing of a full-scale external occulter on the ground is impossible because of the long separations. Therefore, laboratory verification of occulter designs is necessary to validate the optical models used to design and predict occulter performance. At Princeton, we have designed and built a testbed that allows verification of scaled occulter designs whose suppressed shadow is mathematically identical to that of space occulters. The goal of this experiment is to demonstrate a pupil plane suppression of better than 1e-9 with a corresponding image plane contrast of better than 1e-11. The occulter testbed uses a 77.2 m optical propagation distance to realize the flight Fresnel number of 14.5. The scaled mask is placed at 27.2 m from the artificial source and the camera is located 50.0 m from the scaled mask. We will use an etched silicon mask, manufactured by the Microdevices Lab(MDL) of the Jet Propulsion Laboratory(JPL), as the occulter. Based on conversations with MDL, we expect that 0.5 μm feature size is an achievable resolution in the mask manufacturing process and is therefore likely the indicator of the best possible performance. The occulter is illuminated by a diverging laser beam to reduce the aberrations from the optics before the occulter. Here, we present first light result of a sample design operating at a flight Fresnel number and the experimental setup of the testbed. We compare the experimental results with simulations

  5. Floating Exchange Rate Regime

    OpenAIRE

    Quader, Syed Manzur

    2004-01-01

    In recent years, many developing countries having a history of high inflation, unfavorable balance of payment situation and a high level of foreign currencies denominated debt, have switched or are in the process of switching to a more flexible exchange rate regime. Therefore, the stability of the exchange rate and the dynamics of its volatility are more crucial than before to prevent financial crises and macroeconomic disturbances. This paper is designed to find out the reasons behind Bangla...

  6. Study of neoclassical transport and bootstrap current for W7-X in the 1/upsilon regime, using results from the PIES code

    International Nuclear Information System (INIS)

    Nemov, V V; Kalyuzhnyj, V N; Kasilov, S V; Drevlak, M; Nuehrenberg, J; Kernbichler, W; Reiman, A; Monticello, D

    2004-01-01

    For the magnetic field of the Wendelstein 7-X (W7-X) standard high-mirror configuration, computed by the PIES code, taking into account real coil geometry, neoclassical transport and bootstrap current are analysed in the 1/upsilon regime using methods based on the integration along magnetic field lines in a given magnetic field. The zero beta and (beta) = 1% cases are studied. The results are compared to the corresponding results for the vacuum magnetic field directly produced by modular coils. A significant advantage of W7-X over a conventional stellarator resulting from reduced neoclassical transport and from reduced bootstrap current follows from the computations although the neoclassical transport is somewhat larger than that previously obtained for the ideal W7-X model configuration

  7. A pilot study to investigate the effect of a hydration regime upon immediate and 24 h delayed MRI contrast agent reactions

    International Nuclear Information System (INIS)

    Bailey, William; Marshall, Gill; Coals, Jacqui

    2007-01-01

    Purpose: Adverse reaction rates to gadolinium based magnetic resonance imaging (MRI) contrast agents which occur immediately post-injection are well documented. However little research has investigated delayed reaction rates (i.e. 30 min-24 h). This study evaluated the rate of immediate and delayed adverse reaction rates to a gadolinium based MRI contrast agent (Dotarem) and investigated the effect of a hydration regime on the rate of adverse events. Method: Fifty-eight patients received no preparation, prior to administration of the contrast agent, whilst another 58 underwent a hydration protocol. The patients had their answers to a questionnaire recorded immediately after the scanning procedure and also via a follow-up telephone call 24 h later. Results: In the unprepared group 9 patients (15.5%) experienced immediate adverse events, i.e. within 0-30 min, whereas 24 (41.4%) experienced delayed reactions (30 min-24 h) after administration of the contrast agent. In the hydrated patient group 6 (10.3%) experienced an immediate adverse event, whilst 8 (13.7%) experienced delayed events post-injection. The difference in the total reaction rates for the unprepared and hydrated groups was statistically significant for immediate and delayed reactions. The difference in the rates of delayed headache, nausea, dizziness and problems with the injection site, for the unprepared and hydrated groups was statistically significant. Conclusion: An oral hydration regime administered to patients, both before and after MRI contrast agent administration significantly reduced the total number of immediate and delayed reactions. It also significantly reduced delayed headache, nausea, dizziness and problems at the injection site. Whilst this pilot study had methodological shortcomings, the strength of the relationship demonstrated are worthy of further investigation

  8. De Facto Regimes in International Law

    Directory of Open Access Journals (Sweden)

    Jonte van Essen

    2012-02-01

    Full Text Available The ambiguous position of de facto regimes in international law has long been the subject of scholarly debate and a source of political conflict. An assessment of the current standing of these regimes in international law and the consequences of actions by international actors on this status has, however, been long overdue. The manner in which de facto regimes are regarded internationally has serious consequences for the individuals under the influence of this legal grey area. Therefore, the study into this problem and possible solutions is of great significance. The 2011 developments in Northern Africa underline the need of contemporary research into this area. This essay aims to clarify the position of de facto regimes in international law and the influence on their status by actions of international actors. The author first argues that de facto regimes have rights and obligations under international law, which provide them with (some form of international legal personality. He then pleads for a reconsideration of the contemporary legal treatment of these regimes. The author argues against the current system of government recognition and proposes a system that better addresses the needs of both de facto regimes and the international community. 

  9. Acoustophoretic separation of airborne millimeter-size particles by a Fresnel lens

    Science.gov (United States)

    Cicek, Ahmet; Korozlu, Nurettin; Adem Kaya, Olgun; Ulug, Bulent

    2017-03-01

    We numerically demonstrate acoustophoretic separation of spherical solid particles in air by means of an acoustic Fresnel lens. Beside gravitational and drag forces, freely-falling millimeter-size particles experience large acoustic radiation forces around the focus of the lens, where interplay of forces lead to differentiation of particle trajectories with respect to either size or material properties. Due to the strong acoustic field at the focus, radiation force can divert particles with source intensities significantly smaller than those required for acoustic levitation in a standing field. When the lens is designed to have a focal length of 100 mm at 25 kHz, finite-element method simulations reveal a sharp focus with a full-width at half-maximum of 0.5 wavelenghts and a field enhancement of 18 dB. Through numerical calculation of forces and simulation of particle trajectories, we demonstrate size-based separation of acrylic particles at a source sound pressure level of 153 dB such that particles with diameters larger than 0.5 mm are admitted into the central hole, whereas smaller particles are rejected. Besides, efficient separation of particles with similar acoustic properties such as polyethylene, polystyrene and acrylic particles of the same size is also demonstrated.

  10. Biaxial-Type Concentrated Solar Tracking System with a Fresnel Lens for Solar-Thermal Applications

    Directory of Open Access Journals (Sweden)

    Tsung Chieh Cheng

    2016-04-01

    Full Text Available In this paper, an electromechanical, biaxial-type concentrated solar tracking system was designed for solar-thermal applications. In our tracking system, the sunlight was concentrated by the microstructure of Fresnel lens to the heating head of the Stirling engine and two solar cells were installed to provide the power for tracking system operation. In order to obtain the maximum sun power, the tracking system traces the sun with the altitude-azimuth biaxial tracing method and accurately maintains the sun’s radiation perpendicular to the plane of the heating head. The results indicated that the position of heating head is an important factor for power collection. If the sunlight can be concentrated to completely cover the heating head with small heat loss, we can obtain the maximum temperature of the heating head of the Stirling engine. Therefore, the temperature of heating head can be higher than 1000 °C in our experiment on a sunny day. Moreover, the results also revealed that the temperature decrease of the heating head is less than the power decrease of solar irradiation because of the latent heat of copper and the small heat loss from the heating head.

  11. Design and experimental investigation of a stretched parabolic linear Fresnel reflector collecting system

    International Nuclear Information System (INIS)

    Zhu, Yanqing; Shi, Jifu; Li, Yujian; Wang, Leilei; Huang, Qizhang; Xu, Gang

    2016-01-01

    Highlights: • A parabolic primary mirror field is designed to reduce the gap between adjacent mirrors. • The movable receiver can reduce the end losses. • The thermal efficiency of 66% is achieved at Guangzhou in winter. - Abstract: This paper proposes a stretched parabolic linear Fresnel reflector (SPLFR) collecting system. The primary optical mirror field of the SPLFR collecting system and the second-stage concentrator of compound parabolic collector are designed. The mirrors located at the parabolic line are close to each other, which effectively reduce the gap between the adjacent mirrors. The end losses of the receiver are very important, especially in a small-scale collecting system. A movable receiver is introduced for the reduction of the end losses. Moreover, a stretched structure of SPLFR is designed for wind resistance. Finally, the thermal performance of the SPLFR collecting system with fixed and movable receiver located in Guangzhou is tested. The maximum thermal efficiency obtained by this collecting system with movable receiver is 66% which avoid the end losses effectively, and the solar collector thermal loss coefficient is 1.32 W/m"2 °C. The results show that the SPLFR collecting system has excellent thermal performance and a promising application future. Meanwhile, this system will provide a valuable reference for concentrating solar power technology.

  12. 24-GHz LTCC Fractal Antenna Array SoP With Integrated Fresnel Lens

    KAUST Repository

    Ghaffar, Farhan A.

    2012-09-30

    A novel 24-GHz mixed low-temperature co-fired ceramic (LTCC) tape based system-on-package (SoP) is presented, which incorporates a fractal antenna array with an integrated grooved Fresnel lens. The four-element fractal array employs a relatively low dielectric constant substrate (CT707, εr = 6.4), whereas the lens has been realized on a high-dielectric-constant superstrate (CT765, εr = 68.7 ). The two (substrate and superstrate) are integrated through four corner posts to realize the required air gap (focal distance). The fractal array alone provides a measured gain of 8.9 dBi. Simulations predict that integration of this array with the lens increases the gain by 6 dB. Measurements reveal that the design is susceptible to LTCC fabrication tolerances. In addition to high gain, the SoP provides a bandwidth of 8%. The high performance and compact size (24 × 24 × 4.8 mm3 ) of the design makes it highly suitable for emerging wireless applications such as automotive radar front end.

  13. Measurement of an electron-beam size with a beam profile monitor using Fresnel zone plates

    International Nuclear Information System (INIS)

    Iida, K.; Nakamura, N.; Sakai, H.; Shinoe, K.; Takaki, H.; Fujisawa, M.; Hayano, H.; Nomura, M.; Kamiya, Y.; Koseki, T.; Amemiya, Y.; Aoki, N.; Nakayama, K.

    2003-01-01

    We present a non-destructive and real-time beam profile monitor using Fresnel zone plates (FZPs) and the measurement of an electron-beam size with this monitor in the KEK-Accelerator Test Facility (ATF) damping ring. The monitor system has the structure of a long-distance X-ray microscope, where two FZPs constitute an X-ray imaging optics. The synchrotron radiation from the electron beam at the bending magnet is monochromatized by a crystal monochromator and the transverse electron beam image is twenty times magnified by the two FZPs and detected on an X-ray CCD camera. The expected spatial resolution for the selected photon energy of 3.235 keV is sufficiently high to measure the horizontal and vertical beam sizes of the ATF damping ring. With the beam profile monitor, we succeeded in obtaining a clear electron-beam image and measuring the extremely small beam size less than 10 μm. The measured magnification of the X-ray imaging optics in the monitor system was in good agreement with the design value

  14. Pinhole diffraction holography for fabrication of high-resolution Fresnel zone plates.

    Science.gov (United States)

    Sarkar, Sankha S; Solak, Harun H; David, Christian; van der Veen, J Friso

    2014-01-27

    Fresnel zone plates (FZPs) play an essential role in high spatial resolution x-ray imaging and analysis of materials in many fields. These diffractive lenses are commonly made by serial writing techniques such as electron beam or focused ion beam lithography. Here we show that pinhole diffraction holography has potential to generate FZP patterns that are free from aberrations and imperfections that may be present in alternative fabrication techniques. In this presented method, FZPs are fabricated by recording interference pattern of a spherical wave generated by diffraction through a pinhole, illuminated with coherent plane wave at extreme ultraviolet (EUV) wavelength. Fundamental and practical issues involved in formation and recording of the interference pattern are considered. It is found that resolution of the produced FZP is directly related to the diameter of the pinhole used and the pinhole size cannot be made arbitrarily small as the transmission of EUV or x-ray light through small pinholes diminishes due to poor refractive index contrast found between materials in these spectral ranges. We also find that the practical restrictions on exposure time due to the light intensity available from current sources directly imposes a limit on the number of zones that can be printed with this method. Therefore a trade-off between the resolution and the FZP diameter exists. Overall, we find that this method can be used to fabricate aberration free FZPs down to a resolution of about 10 nm.

  15. Solar concentrator modules with silicone-on-glass Fresnel lens panels and multijunction cells.

    Science.gov (United States)

    Rumyantsev, Valery D

    2010-04-26

    High-efficiency multijunction (MJ) solar cells, being very expensive to manufacture, should only be used in combination with solar concentrators in terrestrial applications. An essential cost reduction of electric power produced by photovoltaic (PV) installations with MJ cells, may be expected by the creation of highly-effective, but inexpensive, elements for optical concentration and sun tracking. This article is an overview of the corresponding approach under development at the Ioffe Physical Technical Institute. The approach to R&D of the solar PV modules is based on the concepts of sunlight concentration by small-aperture area Fresnel lenses and "all-glass" module design. The small-aperture area lenses are arranged as a panel with silicone-on-glass structure where the glass plate serves as the front surface of a module. In turn, high-efficiency InGaP/(In)GaAs/Ge cells are arranged on a rear module panel mounted on a glass plate which functions as a heat sink and integrated protective cover for the cells. The developed PV modules and sun trackers are characterized by simple design, and are regarded as the prototypes for further commercialization.

  16. Solar concentrator modules with silicone-onglass Fresnel lens panels and multijunction cells.

    Science.gov (United States)

    Rumyantsev, Valery D

    2010-04-26

    High-efficiency multijunction (MJ) solar cells, being very expensive to manufacture, should only be used in combination with solar concentrators in terrestrial applications. An essential cost reduction of electric power produced by photovoltaic (PV) installations with MJ cells, may be expected by the creation of highly-effective, but inexpensive, elements for optical concentration and sun tracking. This article is an overview of the corresponding approach under development at the Ioffe Physical Technical Institute. The approach to R&D of the solar PV modules is based on the concepts of sunlight concentration by small-aperture area Fresnel lenses and "all-glass" module design. The small-aperture area lenses are arranged as a panel with silicone-on-glass structure where the glass plate serves as the front surface of a module. In turn, high-efficiency InGaP/(In)GaAs/Ge cells are arranged on a rear module panel mounted on a glass plate which functions as a heat sink and integrated protective cover for the cells. The developed PV modules and sun trackers are characterized by simple design, and are regarded as the prototypes for further commercialization.

  17. Molecular dynamics studies of the transient nucleation regime in the freezing of (RbCl)108 clusters

    International Nuclear Information System (INIS)

    Huang, Jinfan; Bartell, L.S.Lawrence S.

    2004-01-01

    The freezing of supercooled liquids in the transient period before a steady state of nucleation is attained has been the subject of a number of theoretical treatments. To our knowledge, no published experimental studies or computer simulations have been carried out in sufficient detail to test definitively the behavior predicted by the various theories. The present molecular dynamics (MD) simulation of 375 nucleation events in small, liquid RbCl clusters, however, yields a reasonably accurate account of the transient region. Despite published criticisms of a 1969 treatment by Kashchiev, it turns out that the behavior observed in the present study agrees with that predicted by Kashchiev. The study also obtains a much more accurate nucleation rate and time lag than reported for MD studies of RbCl previously published in this journal. In addition, it provides estimates of the solid-liquid interfacial free energy and the Granasy thickness of the diffuse solid-liquid interface

  18. Study of physicochemical processes and parameters of regime of diffusion brazing of niobium with titanium, zirconium and vanadium

    International Nuclear Information System (INIS)

    Grishin, V.L.; Lashko, S.V.

    1986-01-01

    Physicochemical processes at diffusion brazing of niobium with titanium, zirconium and vanadium, producing continious series of solid solutions with niobium are studied. Diffusion coefficients, time of isothermal crystallization of soldered welds, as well as the duration of homogenized thermal treatment of soldered welds necessary to provide the given temperature of weld unsoldering

  19. Study of the operation of a diesel engine YaMZ-240 in the regime of gas generator

    Energy Technology Data Exchange (ETDEWEB)

    Degtyarev, G I

    1979-01-01

    Results are presented from studying the diesel engine of type YaMZ-240 during its operation in a mode of idling with increased counter pressure at the exhaust. The possibility is indicated of using the energy of exhaust gases of the engine in the fuel feeding system for mixture-formation and adding steam to the explosive mixture.

  20. Studies on the post-partum ovarian activity of dairy cattle under different feeding regimes in Ecuador

    International Nuclear Information System (INIS)

    Jarrin, J.; Villalba, P.; Guerron, E.; Zurita, E.

    1990-01-01

    In order to monitor ovarian activity in post-partum dairy cows in the Cayambe Valley, Ecuador, 164 cows from three farms were studied. Milk progesterone concentrations (analysed by RIA) and additional data on livestock management, nutritional status and health were compiled. Farms were classified mainly according to nutritional and management status; the better the nutritional status of the cows the sooner they resumed oestrous activity (28.3-31.6 days post-partum). The duration of the first oestrous cycle was found to be variable, 18.0 to 20.4 days. Thirty-one per cent of the study cows did not conceive during the course of the trial and the mean calving interval of those that calved was 426 days. The high incidence of hypofunctional ovaries was a cause for concern on one farm. (author). 6 refs, 4 figs, 2 tabs

  1. The Analysis of Discourses Which Form a Part of the Regime of Practices of Governing: A Governmentality Studies Approach

    Directory of Open Access Journals (Sweden)

    Victoria Haidar

    2007-05-01

    Full Text Available From the perspective of governmentality studies and a critical discourse analysis this paper looks at the interfaces between a social point of view and the mobilization of techniques of decision making. This is illustrated by the discourse analysis of the program between 1907 and 1915 of the National Department of Work in Argentina through which the governing of risks at work was organized within a liberal rational framework. URN: urn:nbn:de:0114-fqs070287

  2. Co-operation and conflict under hard and soft contracting regimes: case studies from England and Wales.

    Science.gov (United States)

    Hughes, David; Allen, Pauline; Doheny, Shane; Petsoulas, Christina; Vincent-Jones, Peter

    2013-01-01

    This paper examines NHS secondary care contracting in England and Wales in a period which saw increasing policy divergence between the two systems. At face value, England was making greater use of market levers and utilising harder-edged service contracts incorporating financial penalties and incentives, while Wales was retreating from the 1990 s internal market and emphasising cooperation and flexibility in the contracting process. But there were also cross-border spill-overs involving common contracting technologies and management cultures that meant that differences in on-the-ground contracting practices might be smaller than headline policy differences suggested. The nature of real-world contracting behaviour was investigated by undertaking two qualitative case studies in England and two in Wales, each based on a local purchaser/provider network. The case studies involved ethnographic observations and interviews with staff in primary care trusts (PCTs) or local health boards (LHBs), NHS or Foundation trusts, and the overseeing Strategic Health Authority or NHS Wales regional office, as well as scrutiny of relevant documents. Wider policy differences between the two NHS systems were reflected in differing contracting frameworks, involving regional commissioning in Wales and commissioning by either a PCT, or co-operating pair of PCTs in our English case studies, and also in different oversight arrangements by higher tiers of the service. However, long-term relationships and trust between purchasers and providers had an important role in both systems when the financial viability of organisations was at risk. In England, the study found examples where both PCTs and trusts relaxed contractual requirements to assist partners faced with deficits. In Wales, news of plans to end the purchaser/provider split meant a return to less precisely-specified block contracts and a renewed concern to build cooperation between LHB and trust staff. The interdependency of local

  3. Hydrodynamics of gas-liquid slug flow along vertical pipes in turbulent regime-An experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Mayor, T.S.; Ferreira, V.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias 4200-465 Porto (Portugal); Campos, J.B.L.M. [Centro de Estudos de Fenomenos de Transporte, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias 4200-465 Porto (Portugal)], E-mail: jmc@fe.up.pt

    2008-08-15

    An experimental study on free-bubbling gas-liquid (air-water) vertical slug flow was developed using a non-intrusive image analysis technique. The flow pattern in the near-wake of the bubbles and in the main liquid between bubbles was turbulent. A single correlation for the bubble-to-bubble interaction is proposed, relating the trailing bubble velocity to the length of the liquid slug ahead of the bubble. The proposed correlation is shown to be independent of column diameter, column vertical coordinate, superficial liquid and gas velocities and the velocity and length of the leading bubble. Frequency distribution curves, averages, modes and standard deviations are reported, for distributions of bubble velocity, bubble length and liquid slug length, for each experimental condition studied. Good agreement was found between theoretical predictions and experimental results regarding the upward velocity of undisturbed bubbles, in a 0.032 m internal diameter column. A considerable discrepancy was found, though, for a 0.052 m internal diameter column. The acquired experimental data are crucial for the development and validation of a robust slug flow simulator.

  4. Hydrodynamics of gas-liquid slug flow along vertical pipes in turbulent regime-An experimental study

    International Nuclear Information System (INIS)

    Mayor, T.S.; Ferreira, V.; Pinto, A.M.F.R.; Campos, J.B.L.M.

    2008-01-01

    An experimental study on free-bubbling gas-liquid (air-water) vertical slug flow was developed using a non-intrusive image analysis technique. The flow pattern in the near-wake of the bubbles and in the main liquid between bubbles was turbulent. A single correlation for the bubble-to-bubble interaction is proposed, relating the trailing bubble velocity to the length of the liquid slug ahead of the bubble. The proposed correlation is shown to be independent of column diameter, column vertical coordinate, superficial liquid and gas velocities and the velocity and length of the leading bubble. Frequency distribution curves, averages, modes and standard deviations are reported, for distributions of bubble velocity, bubble length and liquid slug length, for each experimental condition studied. Good agreement was found between theoretical predictions and experimental results regarding the upward velocity of undisturbed bubbles, in a 0.032 m internal diameter column. A considerable discrepancy was found, though, for a 0.052 m internal diameter column. The acquired experimental data are crucial for the development and validation of a robust slug flow simulator

  5. THE TELEVISION BUSINESS IN INDONESIA: A COMPARATIVE STUDY OF THE OLD REGIME, THE NEW ORDER, AND THE REFORM ERA

    Directory of Open Access Journals (Sweden)

    Rendra Widyatama

    2018-04-01

    Full Text Available This article compares the television industry in Indonesia during the reign of the Old Order, the New Order, and the Reform Era. A full review of television broadcasting in all eras is still rarely carried out by Indonesian researchers. The author uses qualitative research methods in the form of comparative studies and library studies based on secondary data. In this comparison, the author focuses on eleven aspects of the problem, namely; the system of broadcasting, ownership, the form of broadcasting institutions, objectives, funding, broadcast coverage, control, and supervision, licensing, press freedom, media content trends, and society in relation to the television industry. The author found that although since independence Indonesia has been based on Pancasila democracy, in every era of government there have been differences in TV broadcasting arrangements. The Old Order period was more dominated by the role of government. This situation continued during the first 20 years of the New Order government, but in the last ten years of the New Order, the private sector dominated the TV industry. This dominance has continued into the reform era and treats society as a market and a political object. During all periods, it is the government which determines to license, and the implementation of the Broadcasting Act is not strictly enforced. A less strict attitude in the implementation of the Broadcasting Act indicates that the country is flexible and endeavours to find ways to compromise with stakeholders.

  6. Prediction of future hydrological regimes in poorly gauged high altitude basins: the case study of the upper Indus, Pakistan

    Directory of Open Access Journals (Sweden)

    D. Bocchiola

    2011-07-01

    Full Text Available In the mountain regions of the Hindu Kush, Karakoram and Himalaya (HKH the "third polar ice cap" of our planet, glaciers play the role of "water towers" by providing significant amount of melt water, especially in the dry season, essential for agriculture, drinking purposes, and hydropower production. Recently, most glaciers in the HKH have been retreating and losing mass, mainly due to significant regional warming, thus calling for assessment of future water resources availability for populations down slope. However, hydrology of these high altitude catchments is poorly studied and little understood. Most such catchments are poorly gauged, thus posing major issues in flow prediction therein, and representing in fact typical grounds of application of PUB concepts, where simple and portable hydrological modeling based upon scarce data amount is necessary for water budget estimation, and prediction under climate change conditions. In this preliminarily study, future (2060 hydrological flows in a particular watershed (Shigar river at Shigar, ca. 7000 km2, nested within the upper Indus basin and fed by seasonal melt from major glaciers, are investigated.

    The study is carried out under the umbrella of the SHARE-Paprika project, aiming at evaluating the impact of climate change upon hydrology of the upper Indus river. We set up a minimal hydrological model, tuned against a short series of observed ground climatic data from a number of stations in the area, in situ measured ice ablation data, and remotely sensed snow cover data. The future, locally adjusted, precipitation and temperature fields for the reference decade 2050–2059 from CCSM3 model, available within the IPCC's panel, are then fed to the hydrological model. We adopt four different glaciers' cover scenarios, to test sensitivity to decreased glacierized areas. The projected flow duration curves, and some selected flow descriptors are evaluated. The uncertainty of

  7. The Two Regimes of Postwar Shipping

    DEFF Research Database (Denmark)

    Iversen, Martin Jes; Tenold, Stig

    2014-01-01

    the bargaining that accompanied the shift from the national regime to the competitive regime. Specifically, we show that the new regime primarily accommodated the interests of private actors such as shipping companies, rather than the interests of the authorities and the trade unions.......The aim of this article is to illustrate the most important changes in the regulatory framework of the shipping sector from the 1960s to 2010, and to analyse the basis for, and effects of, these changes. In order to explain how the transformation has occurred, we use two traditional maritime...... nations—Denmark and Norway—as case studies. First, we introduce the two regimes of Danish and Norwegian shipping: ‘the national regime’ from the early 1960s to the mid-1970s; and ‘the competitive regime’, which was fully established by the middle of the 1990s and still persists. Then, we briefly sketch...

  8. An experimental study of soil temperature regimes associated with solar disinfestation techniques under greenhouse conditions in Greece.

    Science.gov (United States)

    Garofalakis, I; Tsiros, I; Frangoudakis, A; Chronopoulos, K; Flouri, F

    2006-01-01

    This paper deals with an experimental study of various techniques that have been applied for soil disinfestation purposes under greenhouse conditions. Various meteorological parameters and soil temperatures were measured for four different experimental soil segments (three associated with different disinfestation techniques and one as a reference) at depths varying between 0-1 m and with a time interval of 5 min in a greenhouse located in the Agricultural University of Athens Campus, Greece. Results showed that plastic polyethylene films such as covers, metallic conductors or a combination of both were able to enhance heat transfer and temperature increase in greenhouse soil. For typical disinfestation conditions, the depth-averaged temperature values for plastic covers, metallic conductors, and the combination of both were found to be higher than those for the reference of about 5 degrees C, 12 degrees C and 15 micro C, respectively. Moreover, the remained population percentages 50 days after the initiation of the experiment were found to be 19.3%, 25.3%, 37.3% Kcat 94% of the initial population, for the combination of metallic conductors and plastic covers, metallic conductors, plastic cover, and for the reference, respectively.

  9. Separation and study of nuclides far from beta stability and search for new regimes of nuclear stability

    International Nuclear Information System (INIS)

    Skarestad, M.

    1977-01-01

    In radiochemical separations progress has been made in developing both discontinuous and continuous separation techniques. Outstanding examples of fast, discontinuous separations have been reported from the University of Mainz where chemical separations are performed on a subsecond time scale. However, when experiments have to be performed repeatedly, a continuous separation process delivering a steady source of short-lived species is more appropriate. Such separations are accomplished in the on-line operating solvent extraction system SISAK. The combination of this separation technique with a Gas Jet Recoil Transport (GJRT) system makes it possible to adapt the separation system to different irradiation facilities. The performance of SISAK has been illustrated through the study of short-lived rare-earth isotopes, using conventional gamma-ray spectroscopy. Following some initial test experiments at a 14 MeV neutron generator in Gothenburg the SISAK system was installed at a Philips PW 5320 neutron generator situated in the Dept. of Nuclear Chemistry, Univ. of Oslo in 1972. In the following two years the main effort was devoted to the development of the experimental separation technique although some physics results were obtained in this period. In 1974 the SISAK system was combined with a GJRT arrangement and installed at the Mainz TRIGA reactor. (JIW)

  10. Study of wave-particle interaction from the linear regime to dynamical chaos in a magnetized plasma

    International Nuclear Information System (INIS)

    Fasoli, A.

    1993-10-01

    Deterministic chaos generated by the interaction between charged particles and electrostatic plasma waves has been observed in a linear magnetized plasma. The target plasma is created by a barium Q-source, guaranteeing low fluctuation levels and a high degree of uniformity over an extended plasma volume. Characteristics of the background plasma are investigated by a variety of diagnostic techniques, including laser induced fluorescence (LIF) and optical tagging (OT). Particular tagging schemes and specific theoretical approaches to data interpretation (both for LIF and OT) have been developed during this work. As part of these background plasma studies, special attention has been devoted to an investigation of test-ion cross-field transport under different conditions. Test-ions are created and followed in their motion across the magnetic field lines via spin state tagging. In the unperturbed plasma this motion is found to be a diffusive process, supported by classical mechanisms, even in the presence of relatively high pressures of non-reactive neutral gases injected into the plasma volume. Electrostatic waves are excited using a ring antenna structure encircling the plasma column and electrically isolated from it. This system has been chosen on the basis of a comparative analysis of different ion wave launching methods, including the use of grids, inductive coils coupled electromagnetically to the plasma and modulated high frequency electron waves. Two modes propagating parallel to the magnetic field, one of which has two perpendicular components (ion Bernstein and ion acoustic-like waves), characterize the spectrum excited by the electrostatic ring antenna for a single frequency, f, chosen in the range f ci ci . (author) figs., tabs., 134 refs

  11. Linear Fresnel zone plate based two-state alignment system for 0.25 micron x-ray lithography

    International Nuclear Information System (INIS)

    Chen, G.

    1993-01-01

    X-ray lithography has proven to be a cost effective and promising technique for fabricating Integrated Circuits (ICs) with minimum feature sizes of less than 0.25 μm. Since IC fabrication is a multilevel process, to preserve the functionality of devices, circuit patterns printed at each lithography level must match existing patterns on the wafer with an accuracy of less than 1/3 ∼ 1/5 of the minimum feature size. An alignment system is used to position the mask relative to the wafer so that mask circuit patterns can be printed on the wafer at the designed position. As the minimum printed feature size shrinks, the overlay requirements of a lithography tool become more stringent. A stepper for 0.25 μm feature device fabrication requires an overlay accuracy of 0.075 μm, of which only 0.05 μm (mean + 3σ) is allocated to its alignment system. This thesis presents the development of a linear Fresnel zone late based two-state alignment (TSA) method for a 0.25 μm x-ray lithography tool. The authors first analyze the overlay requirement in a lithography process and the error allocation to the alignment system for a 0.25 μ feature x-ray lithography tool. They then describe the principle of the two-state alignment, its computer simulation and the optimal alignment mark design. They carried out an optical bench test for the one-axes alignment setup and experimentally evaluated the performance of the system. They developed a three-axes TSA system and integrated the system with the ES-3 x-ray beamline to construct the CXrL aligner, an experimental x-ray exposure system in CXrL. They measured the alignment accuracy of the exposure system to be better than 0.035 μm (3σ) on both metal and dielectric alignment mark substrates. They also studied the effect of processing coatings on the alignment signal with different wafer mark substrates. They successfully printed the 0.5 μm gate level patterns for the first NMOS test chip at CXrL

  12. Characteristics of regulatory regimes

    Directory of Open Access Journals (Sweden)

    Noralv Veggeland

    2013-03-01

    Full Text Available The overarching theme of this paper is institutional analysis of basic characteristics of regulatory regimes. The concepts of path dependence and administrative traditions are used throughout. Self-reinforcing or positive feedback processes in political systems represent a basic framework. The empirical point of departure is the EU public procurement directive linked to OECD data concerning use of outsourcing among member states. The question is asked: What has caused the Nordic countries, traditionally not belonging to the Anglo-Saxon market-centred administrative tradition, to be placed so high on the ranking as users of the Market-Type Mechanism (MTM of outsourcing in the public sector vs. in-house provision of services? A thesis is that the reason may be complex, but might be found in an innovative Scandinavian regulatory approach rooted in the Nordic model.

  13. Adaptation in Collaborative Governance Regimes

    Science.gov (United States)

    Emerson, Kirk; Gerlak, Andrea K.

    2014-10-01

    Adaptation and the adaptive capacity of human and environmental systems have been of central concern to natural and social science scholars, many of whom characterize and promote the need for collaborative cross-boundary systems that are seen as flexible and adaptive by definition. Researchers who study collaborative governance systems in the public administration, planning and policy literature have paid less attention to adaptive capacity specifically and institutional adaptation in general. This paper bridges the two literatures and finds four common dimensions of capacity, including structural arrangements, leadership, knowledge and learning, and resources. In this paper, we focus on institutional adaptation in the context of collaborative governance regimes and try to clarify and distinguish collaborative capacity from adaptive capacity and their contributions to adaptive action. We posit further that collaborative capacities generate associated adaptive capacities thereby enabling institutional adaptation within collaborative governance regimes. We develop these distinctions and linkages between collaborative and adaptive capacities with the help of an illustrative case study in watershed management within the National Estuary Program.

  14. Comparative Study on Growth Performance of Transgenic (Over-Expressed OsNHX1 and Wild-Type Nipponbare under Different Salinity Regimes

    Directory of Open Access Journals (Sweden)

    Nurul Kahrani ISHAK

    2015-11-01

    Full Text Available Transgenic Nipponbare which over-expressed a Na+/H+ antiporter gene OsNHX1 was used to compare its growth performance, water status and photosynthetic efficiency with its wild type under varying salinity regimes. Chlorophyll content, quantum yield and photosynthetic rate were measured to assess the impact of salinity stress on photosynthetic efficiency for transgenic and wild-type Nipponbare. Effects of salinity on water status and gas exchange to both lines were studied by measuring water use efficiency, instantaneous transpiration rate and stomatal conductance. Dry shoot weight and leaf area were determined after three months of growth to assess the impacts of salinity on the growth of those two lines. Our study showed that both lines were affected by salinity stress, however, the transgenic line showed higher photosynthetic efficiency, better utilization of water, and better growth due to low transpiration rate and stomatal conductance. Reduction of photosynthetic efficiency exhibited by the wild-type Nipponbare was correlated to its poor growth under salinity stress.

  15. Study of nonlinear optical absorption properties of V{sub 2}O{sub 5} nanoparticles in the femtosecond excitation regime

    Energy Technology Data Exchange (ETDEWEB)

    Molli, Muralikrishna; Bhat Kademane, Abhijit; Pradhan, Prabin; Sai Muthukumar, V. [Sri Sathya Sai Institute of Higher Learning, Department of Physics, Puttaparthi, Andhra Pradesh (India)

    2016-08-15

    In this work, we report for the first time, the nonlinear optical absorption properties of vanadium pentoxide (V{sub 2}O{sub 5}) nanoparticles in the femtosecond excitation regime. V{sub 2}O{sub 5} nanoparticles were synthesized through solution combustion technique. The as-synthesized samples were further characterized using XRD, FESEM, EDAX, TEM and UV-visible spectroscopy. X-ray diffraction results revealed the crystalline nature of the nanoparticles. Electron microscopy studies showed the size of the nanoparticles to be ∝200 nm. Open-aperture z-scan technique was employed to study the nonlinear optical absorption behavior of the synthesized samples using a 100-fs laser pulses at 800 nm from a regeneratively amplified Ti: sapphire laser. The mechanism of nonlinear absorption was found to be a three-photon absorption process which was explained using the density of states of V{sub 2}O{sub 5} obtained using density functional theory. These nanoparticles exhibit strong intensity-dependent nonlinear optical absorption and hence could be considered for optical-power-limiting applications. (orig.)

  16. Fresnel zone-plate based X-ray microscopy in Zernike phase contrast with sub-50 nm resolution at NSRL

    Energy Technology Data Exchange (ETDEWEB)

    Chen Jie; Li Wenjie; Tian Jinping; Liu Longhua; Xiong Ying; Liu Gang; Wu Ziyu; Tian Yangchao [National Synchrotron Radiation Laboratory (China); Liu Yijin [School of Physics (China); Yue Zhengbo; Yu Hanqing [Laboratory of Environmental Engineering, School of Chemistry, University of Science and Technology of China, Hefei Anhui 230029 (China); Wang Chunru, E-mail: ychtian@ustc.edu.c [Institute of Chemistry, Chinese Academy of Sciences, Beijing 10060 (China)

    2009-09-01

    A transmission X-ray microscope using Fresnel zone-plates (FZPs) has been installed at U7A beamline of National Synchrotron Radiation Laboratory (NSRL). The objective FZP with 45 nm outermost zone width delivers a sub-50 nm resolution. A gold phase ring with 2.5 {mu}m thickness and 4 {mu}m width was placed at the focal plane of the objective FZP at 8 keV to produce a negative Zernike phase contrast. A series of samples were used to test the performance of the Zernike phase contrast X-ray microscopy.

  17. Fresnel zone-plate based X-ray microscopy in Zernike phase contrast with sub-50 nm resolution at NSRL

    International Nuclear Information System (INIS)

    Chen Jie; Li Wenjie; Tian Jinping; Liu Longhua; Xiong Ying; Liu Gang; Wu Ziyu; Tian Yangchao; Liu Yijin; Yue Zhengbo; Yu Hanqing; Wang Chunru

    2009-01-01

    A transmission X-ray microscope using Fresnel zone-plates (FZPs) has been installed at U7A beamline of National Synchrotron Radiation Laboratory (NSRL). The objective FZP with 45 nm outermost zone width delivers a sub-50 nm resolution. A gold phase ring with 2.5 μm thickness and 4 μm width was placed at the focal plane of the objective FZP at 8 keV to produce a negative Zernike phase contrast. A series of samples were used to test the performance of the Zernike phase contrast X-ray microscopy.

  18. Design of optical element combining Fresnel lens with microlens array for uniform light-emitting diode lighting.

    Science.gov (United States)

    Wang, Guangzhen; Wang, Lili; Li, Fuli; Kong, Depeng

    2012-09-01

    One kind of optical element combining Fresnel lens with microlens array is designed simply for LED lighting based on geometrical optics and nonimaging optics. This design method imposes no restriction on the source intensity pattern. The designed element has compact construction and can produce multiple shapes of illumination distribution. Taking square lighting as an example, tolerance analysis is carried out to determine tolerance limits for applying the element in the assembly process. This element can produce on-axis lighting and off-axis lighting.

  19. Ecosystem regime shifts disrupt trophic structure.

    Science.gov (United States)

    Hempson, Tessa N; Graham, Nicholas A J; MacNeil, M Aaron; Hoey, Andrew S; Wilson, Shaun K

    2018-01-01

    Regime shifts between alternative stable ecosystem states are becoming commonplace due to the combined effects of local stressors and global climate change. Alternative states are characterized as substantially different in form and function from pre-disturbance states, disrupting the delivery of ecosystem services and functions. On coral reefs, regime shifts are typically characterized by a change in the benthic composition from coral to macroalgal dominance. Such fundamental shifts in the benthos are anticipated to impact associated fish communities that are reliant on the reef for food and shelter, yet there is limited understanding of how regime shifts propagate through the fish community over time, relative to initial or recovery conditions. This study addresses this knowledge gap using long-term data of coral reef regime shifts and recovery on Seychelles reefs following the 1998 mass bleaching event. It shows how trophic structure of the reef fish community becomes increasingly dissimilar between alternative reef ecosystem states (regime-shifted vs. recovering) with time since disturbance. Regime-shifted reefs developed a concave trophic structure, with increased biomass in base trophic levels as herbivorous species benefitted from increased algal resources. Mid trophic level species, including specialists such as corallivores, declined with loss of coral habitat, while biomass was retained in upper trophic levels by large-bodied, generalist invertivores. Recovering reefs also experienced an initial decline in mid trophic level biomass, but moved toward a bottom-heavy pyramid shape, with a wide range of feeding groups (e.g., planktivores, corallivores, omnivores) represented at mid trophic levels. Given the importance of coral reef fishes in maintaining the ecological function of coral reef ecosystems and their associated fisheries, understanding the effects of regime shifts on these communities is essential to inform decisions that enhance ecological

  20. The role of the media in establishing international security regimes

    Directory of Open Access Journals (Sweden)

    Chanan Naveh

    2005-04-01

    Full Text Available This article focuses primarily on the media's impact on international security regimes. It explores the ways in which the media affect the lifecycles of international regimes, from the time they are first conceived of, through their establishment, consolidation and stabilization, up until their ultimate demise. Although this paper highlights the media's role in the evolution of security regimes, it is clear that, regardless of the regime in question, media play a role throughout the lifecycle of all international regimes, whatever their character. In order to analyze the relationships of the media with security regimes in general, and specifically their contribution to each stage in their development, the article utilizes methodologies from the field of communication studies. It examines the media's agenda, "news values" and various functions, and their ability to mobilize public support for the particular issue of the regime. To date, most studies have explored the interaction between media communication patterns and global developments at the state level, or in relation to the formulation of foreign policy, while largely ignoring the international dimension of the relationship. This article attempts to remedy this situation, and the relevant processes are analysed in a case study of the anti-Iraq international security regime. It should be noted that although the paper focuses on the specific anti-Iraqi regime, it is part of a more general Anti-Rogue actors regime which includes the war against global terrorism. The study of the development of the anti-Iraq press-security regime teaches us that during international crises the media mobilize and unanimously support the regime fighting the "bad guys." But, when the regime develops and enters disputed turfs and begins to lose its legitimacy, media support diminishes, and the media may even develop into an opposing force and may join the actors fighting against this regime. Moreover, the study of

  1. Bispectoral index scores of pediatric patients under dental treatment and recovery conditions: Study of children assigned for general anesthesia under propofol and isofloran regimes

    Directory of Open Access Journals (Sweden)

    Dana Tahririan

    2016-01-01

    Full Text Available Background: This study was planned to determine the relationship between bispectoral index (BIS during dental treatment and recovery conditions in children undergoing two regimes of anesthesia of propofol and isoflurane. Materials and Methods: In this single-blind clinical trial study, 57 4-7-year-old healthy children who had been referred for dental treatment under general anesthesia between 60 and 90 min were selected by convenience sampling and assigned to two groups, after obtaining their parents′ written consent. The anesthesia was induced by inhalation. For the first group, the anesthesia was preserved by a mixture of oxygen (50%, nitrous oxide (50%, and isoflurane (1%. For the second group, the anesthesia was preserved by a mixture of oxygen (50%, nitrous oxide (50%, and propofol was administered intravenously at a dose of 100 Ng/kg/min. The patients′ vital signs, BIS, and agitation scores were recorded every 10 min. The data were analyzed by repeated measure ANOVA and t-tests at a significance level of α = 0.05 using SPSS version 20. Results: The results of independent t-test for anesthesia time showed no statistically significant difference between isoflurane and propofol (P = 0.87. Controlling age, the BIS difference between the two anesthetic agents was not significant (P > 0.05; however, it was negatively correlated with the duration of anesthesia and the discharge time (P = 0.001, r = -0.308 and (P < 0.001, r = -0.55. Conclusion: The same depth of anesthesia is produced by propofol and isoflurane, but lower recovery complications from anesthesia are observed with isoflurane.

  2. DEM study of the size-induced segregation dynamics of a ternary-size granular mixture in the rolling-regime rotating drum

    Science.gov (United States)

    Yang, Shiliang; Zhang, Liangqi; Luo, Kun; Chew, Jia Wei

    2017-12-01

    Segregation induced by size, shape, or density difference of the granular material is inevitable in both natural and industrial processes; unfortunately, the underlying mechanism is still not fully understood. In view of the ubiquitous continuous particle size distributions, this study builds on the considerable knowledge gained so far from binary-size mixtures and extends it to a ternary-size mixture to understand the impact of the presence of a third particle size in the three-dimensional rotating drum operating in the rolling flow regime. The discrete element method is employed. The evolution of segregation, the active-passive interface, and the dynamical response of the particle-scale characteristics of the different particle types in the two regions are investigated. The results reveal that the medium particles are spatially sandwiched in between the large and small particles in both the radial and axial directions and therefore exhibit behaviors intermediate to the other two particle types. Compared to the binary-size mixture, the presence of the medium particles leads to (i) higher purity of small particles in the innermost of the radial core, causing a decrease of the translational velocity of small particles; (ii) decrease and increase of the collision forces exerted on, respectively, the large and small particles in both regions; and (iii) increase in the relative ratio of the active-passive exchange rates of small to large particles. The results obtained in the current study therefore provide valuable insights regarding the size-segregation dynamics of granular mixtures with constituents of different sizes.

  3. Theoretical extension and experimental demonstration of spectral compression in second-harmonic generation by Fresnel-inspired binary phase shaping

    Science.gov (United States)

    Li, Baihong; Dong, Ruifang; Zhou, Conghua; Xiang, Xiao; Li, Yongfang; Zhang, Shougang

    2018-05-01

    Selective two-photon microscopy and high-precision nonlinear spectroscopy rely on efficient spectral compression at the desired frequency. Previously, a Fresnel-inspired binary phase shaping (FIBPS) method was theoretically proposed for spectral compression of two-photon absorption and second-harmonic generation (SHG) with a square-chirped pulse. Here, we theoretically show that the FIBPS can introduce a negative quadratic frequency phase (negative chirp) by analogy with the spatial-domain phase function of Fresnel zone plate. Thus, the previous theoretical model can be extended to the case where the pulse can be transformed limited and in any symmetrical spectral shape. As an example, we experimentally demonstrate spectral compression in SHG by FIBPS for a Gaussian transform-limited pulse and show good agreement with the theory. Given the fundamental pulse bandwidth, a narrower SHG bandwidth with relatively high intensity can be obtained by simply increasing the number of binary phases. The experimental results also verify that our method is superior to that proposed in [Phys. Rev. A 46, 2749 (1992), 10.1103/PhysRevA.46.2749]. This method will significantly facilitate the applications of selective two-photon microscopy and spectroscopy. Moreover, as it can introduce negative dispersion, hence it can also be generalized to other applications in the field of dispersion compensation.

  4. Fire regime in Mediterranean ecosystem

    Science.gov (United States)

    Biondi, Guido; Casula, Paolo; D'Andrea, Mirko; Fiorucci, Paolo

    2010-05-01

    The analysis of burnt areas time series in Mediterranean regions suggests that ecosystems characterising this area consist primarily of species highly vulnerable to the fire but highly resilient, as characterized by a significant regenerative capacity after the fire spreading. In a few years the area burnt may once again be covered by the same vegetation present before the fire. Similarly, Mediterranean conifer forests, which often refers to plantations made in order to reforest the areas most severely degraded with high erosion risk, regenerate from seed after the fire resulting in high resilience to the fire as well. Only rarely, and usually with negligible damages, fire affects the areas covered by climax species in relation with altitude and soil types (i.e, quercus, fagus, abies). On the basis of these results, this paper shows how the simple Drossel-Schwabl forest fire model is able to reproduce the forest fire regime in terms of number of fires and burned area, describing whit good accuracy the actual fire perimeters. The original Drossel-Schwabl model has been slightly modified in this work by introducing two parameters (probability of propagation and regrowth) specific for each different class of vegetation cover. Using model selection methods based on AIC, the model with the optimal number of classes with different fire behaviour was selected. Two different case studies are presented in this work: Regione Liguria and Regione Sardegna (Italy). Both regions are situated in the center of the Mediterranean and are characterized by a high number of fires and burned area. However, the two regions have very different fire regimes. Sardinia is affected by the fire phenomenon only in summer whilst Liguria is affected by fires also in winter, with higher number of fires and larger burned area. In addition, the two region are very different in vegetation cover. The presence of Mediterranean conifers, (Pinus Pinaster, Pinus Nigra, Pinus halepensis) is quite spread in

  5. Assessment of dam construction impact on hydrological regime changes in lowland river – A case of study: the Stare Miasto reservoir located on the Powa River

    Directory of Open Access Journals (Sweden)

    Sojka Mariusz

    2016-09-01

    Full Text Available The purpose of the presented research is analysis and assessment of the Stare Miasto reservoir impact on the hydrological regime changes of the Powa River. The reservoir was built in 2006 and is located in the central part of Poland. The total area of inundation in normal conditions is 90.68 ha and its capacity is 2.159 mln m3. Hydrological regime alteration of the Powa River is analysed on the basis of daily flows from the Posoka gauge station observed during period 1974–2014. Assessment of hydrological regime changes is carried out on the basis of Range of Variability Approach (RVA method. All calculations are made by means of Indicators of Hydrologic Alteration (IHA software version 7.1.0.10. The analysis shows that the Stare Miasto reservoir has a moderate impact on hydrological regime of the Powa River. Construction of the reservoir has positive effect on stability of minimal flows, which are important for protection of river ecosystems. The results obtained indicate that the Stare Miasto reservoir reduces a spring peak flow and enables to moderate control of floods.

  6. Thermal regime at the Upper Stillwater dam site, Uinta mountains, Utah: Implications for terrain, microclimate and structural corrections in heat flow studies

    Science.gov (United States)

    Bauer, Michael S.; Chapman, David S.

    1986-08-01

    A detailed study of the subsurface thermal regime at the Upper Stillwater dam site, Uinta Mountains, northeast Utah, has been made. Temperature measurements were made in 36 drillholes located within a 1 km 2 area and ranging in depth from 20 to 97 m. Holes less than about 40 m deep were used only to obtain information about spatial variations in mean annual surface temperature. Several holes in or near talus slopes at the sides of the canyons have temperature minima approaching 0°C between 10 and 20 m indicating the presence of year-round ice at the base of the talus. Another set of holes show transient thermal effects of surface warming resulting from clearing of a construction site 3.5 years prior to our measurements. Most of the remaining holes show conductive behavior and have gradients ranging from 13° to 17°C km -1. Measurements made on 44 core samples yield a thermal conductivity of 5.6 (std. dev. 0.35) W m -1 K -1 for the Precambrian quartzite present. Surface heat flow estimates for these holes range from 70 to 100 mW m -2. However, the local disturbance of the thermal field by topography and microclimate is considerable. A finite difference method used to model these effects yielded a locally corrected Upper Stillwater heat flow of about 75 mW m -2. A final correction to account for the effects of refraction of heat from the low conductivity sedimentary rocks in the Uinta Basin into the high conductivity quartzite at the dam site, produced a regionally corrected Upper Stillwater heat flow between 60 and 65 mW m -2. This value is consistent with the observed heat flow of 60 mW m -2 in the Green River Basin to the north and the Uinta Basin to the south.

  7. Coulomb drag in the mesoscopic regime

    DEFF Research Database (Denmark)

    Mortensen, N. Asger; Flensberg, Karsten; Jauho, Antti-Pekka

    2002-01-01

    We present a theory for Coulomb drug between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... means such as perturbation theory or random matrix theory. The physics of Coulomb drag in the mesoscopic regime is very different from Coulomb drag between extended electron systems. In the mesoscopic regime we in general find fluctuations of the drag comparable to the mean value. Examples are vanishing...

  8. Coulomb drag in the mesoscopic regime

    DEFF Research Database (Denmark)

    Mortensen, N.A.; Flensberg, Karsten; Jauho, Antti-Pekka

    2002-01-01

    We present a theory for Coulomb drag between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... means such as perturbation theory or random matrix theory. The physics of Coulomb drag in the mesoscopic regime is very different from Coulomb drag between extended electron systems. In the mesoscopic regime we in general find fluctuations of the drag comparable to the mean value. Examples are vanishing...

  9. Regimes of flow past a vortex generator

    DEFF Research Database (Denmark)

    Velte, Clara Marika; Okulov, V.L.; Naumov, I.V.

    2012-01-01

    A complete parametric investigation of the development of multi-vortex regimes in a wake past simple vortex generator has been carried out. It is established that the vortex structure in the wake is much more complicated than a simple monopole tip vortex. The vortices were studied by stereoscopic...... particle image velocimetry (SPIV). Based on the obtained SPIV data, a map of the regimes of flow past the vortex generator has been constructed. One region with a developed stable multivortex system on this map reaches the vicinity of the optimum angle of attack of the vortex generator....

  10. Flocking regimes in a simple lattice model.

    Science.gov (United States)

    Raymond, J R; Evans, M R

    2006-03-01

    We study a one-dimensional lattice flocking model incorporating all three of the flocking criteria proposed by Reynolds [Computer Graphics 21, 4 (1987)]: alignment, centering, and separation. The model generalizes that introduced by O. J. O'Loan and M. R. Evans [J. Phys. A. 32, L99 (1999)]. We motivate the dynamical rules by microscopic sampling considerations. The model exhibits various flocking regimes: the alternating flock, the homogeneous flock, and dipole structures. We investigate these regimes numerically and within a continuum mean-field theory.

  11. Misalignment under different exchange rate regimes: the case of Turkey

    OpenAIRE

    Dağdeviren, Sengül; Ogus Binatli, Ayla; Sohrabji, Niloufer

    2011-01-01

    The paper examines misalignment of the Turkish lira between 1998 to 2008. Misalignment, specifically overvaluation has been linked to fixed exchange rate regimes. By studying the case of Turkey during this period which covers both a fixed and floating exchange rate regime, we contribute to the literature on the relation between misalignment and exchange rate regimes. We first estimate the equilibrium real exchange rate for Turkey, then compute misalignment and finally test for structural brea...

  12. A numerical study on the forced convection heat transfer from an isothermal and isoflux sphere in the steady symmetric flow regime

    Energy Technology Data Exchange (ETDEWEB)

    Dhole, S.D.; Chhabra, R.P. [Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208 016 (India); Eswaran, V. [Department of Mechanical Engineering, Indian Institute of Technology, Kanpur 208 016 (India)

    2006-03-15

    The effects of Reynolds and Prandtl numbers on the heat transfer characteristics of an unconfined sphere for different thermal boundary conditions (isothermal and isoflux) on the sphere surface have been investigated numerically by using a finite volume method for the range of conditions as 5=regime. The variation of local Nusselt number on the sphere surface shows the effect of Prandtl number on heat transfer from a sphere in this flow regime. In addition, this work also demonstrates an approach to solve such flow problems using the Cartesian form of the field equations. (author)

  13. Characteristic groundwater level regimes in the capture zones of radial collector wells and importance of identification (Case study of Belgrade Groundwater Source

    Directory of Open Access Journals (Sweden)

    Božović Đorđije

    2016-01-01

    Full Text Available Assessment of the operating modes of radial collector wells reveals that the pumping levels in the well caissons are very low relative to the depth/elevation of the laterals, which is a common occurrence at Belgrade Groundwater Source. As a result, well discharge capacities vary over a broad range and groundwater levels in the capture zones differ even when the rate of discharge is the same. Five characteristic groundwater level regimes are identified and their origin is analyzed using representative wells as examples. The scope and type of background information needed to identify the groundwater level regime are presented and an interpretation approach is proposed for preliminary assessment of the aquifer potential at the well site for providing the needed amount of groundwater. [Projekat Ministarstva nauke Republike Srbije, br. OI176022, br. TR33039 i br. III43004

  14. Winter microclimatic regime of low-altitude scree slopes and its relation to topography: case study from the Ceske Stredohori Mts. (N Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Raška, P.; Kirchner, Karel; Raška, M.

    2011-01-01

    Roč. 34, č. 2 (2011), s. 235-246 ISSN 0391-9838 Institutional research plan: CEZ:AV0Z30860518 Keywords : scree * microclimate * thermal regime * topography * Česke Středohoří Mts Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.468, year: 2011 http://lsru.geography.ujep.cz/documents/raskaetal_2011b.pdf

  15. Plugging regime in the pump limiter throat

    International Nuclear Information System (INIS)

    Ghendrih, P.; Grosman, A.; Samain, A.; Capes, H.; Morera, J.P.

    1988-08-01

    The plugging regime -with no outstreaming neutral flux- is studied for a closed configuration pump limiter (throat). We derive the plugging length and the neutral density build-up at the neutralizer plate. The analytical expressions are supported by numerical evidence. We find an improved efficiency related to the throat effect mainly due to neutral-sidewall interactions

  16. Photoluminescence Studies of P-type Modulation Doped GaAs/AlGaAs Quantum Wells in the High Doping Regime

    Science.gov (United States)

    Wongmanerod, S.; Holtz, P. O.; Reginski, K.; Bugaiski, M.; Monemar, B.

    The influence of high Be-acceptor doping on the modulation-doped GaAs/Al0.3Ga0.7As quantum wells structures has been optically studied by using the low-temperature photoluminescence (PL) and photoluminescence excitation (PLE) techniques.The modulation doped samples were grown by the molecular-beam epitaxy technique with a varying Be acceptor concentration ranging from 1×1018 to 8×1018cm-3. Several novels physical effects were observed. The main effect is a significant shift of the main emission towards lower energies as the doping concentrations increase. There are two contradictory mechanisms, which determine the peak energy of the main emission; the shrinkage of the effective bandgap due to many body effects and the reduction of the exciton binding energy due to the carrier screening effect. We conclude that the first one is the dominating effect. At a sufficiently high doping concentration (roughly 2×1018cm-3), the lineshape of the main PL emission is modified, and a new feature, the so called Fermi-edge singularity (FES), appears on the high energy side of the PL emission and exhibits a blue-shift as a function of doping concentration. This feature has been found to be very sensitive to a temperature change, already in the range of 4.4-50K. In addition, PLE spectra with a suitable detection energy show that the absorption edge is blue-shifted with respect to the PL main emission. The resulting Stoke shift is due to phase-space-filling of the carriers, in agreement with the FES interpretation. Finally, we have found from the PLE spectra that the exciton quenching is initiated in the same doping regime. Compared to the exciton quenching in other p-type structures, the critical acceptor concentration required to quench the excitons is significantly lower than in the case of 2D structures with acceptor doping within the well, but larger than in the case of 3D bulk.

  17. Remote Sensing Applied to the Study of Fire Regime Attributes and Their Influence on Post-Fire Greenness Recovery in Pine Ecosystems

    Directory of Open Access Journals (Sweden)

    Víctor Fernández-García

    2018-05-01

    Full Text Available We aimed to analyze the relationship between fire regime attributes and the post-fire greenness recovery of fire-prone pine ecosystems over the short (2-year and medium (5-year term after a large wildfire, using both a single and a combined fire regime attribute approach. We characterized the spatial (fire size, temporal (number of fires, fire recurrence, and return interval, and magnitude (burn severity of the last fire fire regime attributes throughout a 40-year period with a long-time series of Landsat imagery and ancillary data. The burn severity of the last fire was measured by the dNBR (difference of the Normalized Burn Ratio spectral index, and classified according to the ground reference values of the CBI (Composite Burn Index. Post-fire greenness recovery was obtained through the difference of the NDVI (Normalized Difference Vegetation Index between pre- and post-fire Landsat scenes. The relationship between fire regime attributes (single attributes: fire recurrence, fire return interval, and burn severity; combined attributes: fire recurrence-burn severity and fire return interval-burn severity and post-fire greenness recovery was evaluated using linear models. The results indicated that all the single and combined attributes significantly affected greenness recovery. The single attribute approach showed that high recurrence, short return interval and low severity situations had the highest vegetation greenness recovery. The combined attribute approach allowed us to identify a wider variety of post-fire greenness recovery situations than the single attribute one. Over the short term, high recurrence as well as short return interval scenarios showed the best post-fire greenness recovery independently of burn severity, while over the medium term, high recurrence combined with low severity was the most recovered scenario. This novel combined attribute approach (temporal plus magnitude could be of great value to forest managers in the

  18. Current US nuclear liability regime

    International Nuclear Information System (INIS)

    Brown, O.F.

    2000-01-01

    The Price-Anderson Act Adopted by US Congress in 1957 as the world's first national nuclear liability regime. It is a comprehensive, complicated and unique system and stems from special features of US legal regime and federal system of government. It differs from other systems by providing for 'economic', not legal; channeling of liability to facility operator and not recommended as model for other states, but most features adopted by other states and international conventions

  19. Totalitäre Regimes

    OpenAIRE

    Merkel, Wolfgang

    2004-01-01

    "The development of the term and the analytical concept of totalitarianism have gone through several stages since the 1920s. However, even in its most sophisticated form, the version seen in Friedrich/ Brzezinski, the concept exhibits substantial systematic classification problems and analytical weaknesses. This article attempts to frame the type of totalitarian regime within a general typology of political regimes. Special attention is dedicated to the problem of distinguishing autocra...

  20. Endogenous Monetary Policy Regime Change

    OpenAIRE

    Troy Davig; Eric M. Leeper

    2006-01-01

    This paper makes changes in monetary policy rules (or regimes) endogenous. Changes are triggered when certain endogenous variables cross specified thresholds. Rational expectations equilibria are examined in three models of threshold switching to illustrate that (i) expectations formation effects generated by the possibility of regime change can be quantitatively important; (ii) symmetric shocks can have asymmetric effects; (iii) endogenous switching is a natural way to formally model preempt...

  1. Multi-Fresnel lenses pumping approach for improving high-power Nd:YAG solar laser beam quality.

    Science.gov (United States)

    Liang, Dawei; Almeida, Joana

    2013-07-20

    To significantly improve the present-day high-power solar laser beam quality, a three-stage multi-Fresnel lenses approach is proposed for side-pumping either a Nd:YAG single-crystal or a core-doped Sm(3+)Nd:YAG ceramic rod. Optimum pumping and laser beam parameters are found through ZEMAX and LASCAD numerical analysis. The proposed scheme offers a uniform absorption profile along the rod. 167 W laser power can be achieved, corresponding to 29.3 W/m(2) collection efficiency. High brightness figure of merit of 8.34 W is expected for the core-doped rod within a convex-concave resonator, which is 1300 times higher than that of the most-recent high-power solar laser.

  2. Analysis and interpretation of soft X-ray photographs of coronal active regions taken with Fresnel zone plates. I

    International Nuclear Information System (INIS)

    Kraemer, G.; Einighammer, H.J.; Elwert, G.; Braeuninger, H.; Fink, H.H.; Truemper, J.

    1978-01-01

    Soft X-ray photographs of the Sun taken at O VII 21.6 A and in a spectral band ranging from 13.2 to 22.1 A have been analysed in order to establish spatially resolved maps of temperature and emission measure for several active regions in the corona. The photographs were taken on 11 March, 1971, and on 2 March, 1972, with Fresnel zone plate cameras which were flown on ESRO and NRI sounding rockets. The authors deal with those aspects of the instrumentation which are important for setting up a suitable image analysis procedure. The characteristics of the wavelength dependent image formation by zone plates combined with absorption filters are discussed. Results of the calibration of the X-ray film are given. Then a specific iterative data reduction procedure is described and finally the resulting maps of temperature and emission measure are presented for a selected active region. (Auth.)

  3. Space-bandwidth ratio as a means of choosing between Fresnel and other linear canonical transform algorithms.

    Science.gov (United States)

    Healy, John J; Sheridan, John T

    2011-05-01

    The product of the spatial and spatial frequency extents of a wave field has proven useful in the analysis of the sampling requirements of numerical simulations. We propose that the ratio of these quantities is also illuminating. We have shown that the distance at which the so-called "direct method" becomes more efficient than the so-called "spectral method" for simulations of Fresnel transforms may be written in terms of this space-bandwidth ratio. We have proposed generalizations of these algorithms for numerical simulations of general ABCD systems and derived expressions for the "transition space-bandwidth ratio," above which the generalization of the spectral method is the more efficient algorithm and below which the generalization of the direct method is preferable.

  4. The mini-dome Fresnel lens photovoltaic concentrator array - Current status of component and prototype panel testing

    Science.gov (United States)

    Piszczor, M. F.; Swartz, C. K.; O'Neill, M. J.; Mcdanal, A. J.; Fraas, L. M.

    1990-01-01

    NASA Lewis and ENTECH have been developing a high-efficiency, lightweight space photovoltaic concentrator array. The emphasis of the program has shifted to fabrication and testing of the minidome Fresnel lens and other array components. Protototype lenses have been tested for optical efficiency, with results around 90 percent, and tracking error performance. The results of these tests have been very consistent with the predicted analytical performance. Work has also progressed in the fabrication of the array support structure. Recent advances in 30 percent efficient stacked cell technology will have a significant effect on the array performance. It is concluded that near-term array performance goals of 300 W/sq m and 100 W/kg are feasible.

  5. Design and analysis of a curved cylindrical Fresnel lens that produces high irradiance uniformity on the solar cell.

    Science.gov (United States)

    González, Juan C

    2009-04-10

    A new type of convex Fresnel lens for linear photovoltaic concentration systems is presented. The lens designed with this method reaches 100% of geometrical optical efficiency, and the ratio (Aperture area)/(Receptor area) is up to 75% of the theoretical limit. The main goal of the design is high uniformity of the radiation on the cell surface for each input angle inside the acceptance. The ratio between the maximum and the minimum irradiance on points of the solar cell is less than 2. The lens has been designed with the simultaneous multiple surfaces (SMS) method of nonimaging optics, and ray tracing techniques have been used to characterize its performance for linear symmetry systems.

  6. Multilayer on-chip stacked Fresnel zone plates: Hard x-ray fabrication and soft x-ray simulations

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kenan; Wojcik, Michael J.; Ocola, Leonidas E.; Divan, Ralu; Jacobsen, Chris

    2015-11-01

    Fresnel zone plates are widely used as x-ray nanofocusing optics. To achieve high spatial resolution combined with good focusing efficiency, high aspect ratio nanolithography is required, and one way to achieve that is through multiple e-beam lithography writing steps to achieve on-chip stacking. A two-step writing process producing 50 nm finest zone width at a zone thickness of 1.14 µm for possible hard x-ray applications is shown here. The authors also consider in simulations the case of soft x-ray focusing where the zone thickness might exceed the depth of focus. In this case, the authors compare on-chip stacking with, and without, adjustment of zone positions and show that the offset zones lead to improved focusing efficiency. The simulations were carried out using a multislice propagation method employing Hankel transforms.

  7. Increasingly Equalized? A Study of Part-Time Work in ‘Old’ and ‘New’ Part-Time Work Regimes

    OpenAIRE

    Heidi Nicolaisen

    2011-01-01

    Recent debates on equalization of part-time work alongside full-time work stress the importance of high quality part-time jobs. This paper compares equalization in banking in three countries: two `old´ part-time work regimes, Norway and Sweden, and Ireland, where part-time work started to increase more recently. Banking is particularly interesting as a sector with a high proportion of female employment and good working conditions. One main interest is the role of regulations and how they are ...

  8. Static converters power supply: transient regimes; Alimentation par convertisseurs statiques: regimes transitoires

    Energy Technology Data Exchange (ETDEWEB)

    Pasqualini, G. [Ecole Superieure d`Electricite (France)

    1997-08-01

    Direct current motors, asynchronous and variable speed synchronous motors are generally supplied with static converters. Speed variation is obtained by voltage variation in DC motors and by frequency variation in AC motors. In these conditions, these motors are running continuously in transient regimes: the DC motors current is not direct and the AC motors current is not sinusoidal. This situation leads to pulsing couples in the shaft line and to an increase of Joule effect losses. The aim of this paper is to present the methods of study of the electric motors functioning using the shape of the power voltages given by converters and mathematical models of these machines. The synchronous machines are rapidly described while the asynchronous machines are studied using Ku`s transformation instead of Park`s transformation for simplification. For each type of machine, calculation methods allow to determine their current, additional losses and couple characteristics. The transient regimes considered are those remaining when the motor is running at a constant speed and defined regime (supply voltages are periodical functions of time). These transient regimes are identically reproducing with a frequency which is a multiple of the converters supply frequency. Transient regimes due to functioning changes of the motor, such as resisting couple or power supply frequency variations, are not considered in this study. (J.S.) 9 refs.

  9. How does technological regime affect performance of technology development projects?

    NARCIS (Netherlands)

    Song, Michael; Hooshangi, Soheil; Zhao, Y. Lisa; Halman, Johannes I.M.

    2014-01-01

    In this study, we examine how technological regime affects the performance of technology development projects (i.e., project quality, sales, and profit). Technological regime is defined as the set of attributes of a technological environment where the innovative activities of firms take place.

  10. Assessment of climate change impact on river flow regimes in The Red River Delta, Vietnam – A case study of the Nhue-Day River Basin

    Directory of Open Access Journals (Sweden)

    Phan Cao Duong

    2016-09-01

    Full Text Available Global warming has caused dramatic changes in regional climate variability, particularly regarding fluctuations in temperature and rainfall. Thus, it is predicted that river flow regimes will be altered accordingly. The purpose of this paper is to present the results of modeling such changes by simulating discharge using the HEC-HMS model. The precipitation was projected using super-high resolution multiple climate models (20 km resolution with newly updated emission scenarios as the input for the HEC-HMS model for flow analysis at the Red River Basin in the northern area of Vietnam. The findings showed that climate change impact on the river flow regimes tend towards a decrease in the dry season and a longer duration of flood flow. A slight runoff reduction is simulated for November while a considerable runoff increase is modeled for July and August amounting to 30% and 25%, respectively. The discharge scenarios serve as a basis for water managers to develop suitable adaptation methods and responses on the river basin scale.

  11. Study of self-pollination and capitula characteristics in globe artichoke (Cynara cardunculus var. scolymus Hayek L. under different irrigation regimes

    Directory of Open Access Journals (Sweden)

    Nouraei, Sina

    2016-07-01

    Full Text Available In order to estimate the drought effects on capitula characteristics and self-pollination of globe artichoke (Cynara cardunculus var. scolymus Hayek L., the randomized complete block design was carried out with three irrigation regimes (20 %, 50 % and 80 % depletion of soil available water and six replicates. The artichoke is mostly open-pollinated, however, after covering the buds and isolation of flowers to prevent cross pollination, 1.79 % self-pollination was observed and this amount was not affected by different irrigation regimes. In stress conditions (50 % and 80 % water depletion as well as non-stress condition (20 % water depletion, plants with respectively one and two medium capitula and without small capitula had most relative frequencies in the population and drought stress increased these relative frequencies by reducing the number of medium and small capitula in plants. In addition, Capitula size and dry weight were significantly affected by water stress. Water shortage induced severe decrease in length and dry weight of all capitula including large, medium and small, although capitula width was less affected by water deficit and only slight decline in medium (12.5 % and small capitula (23.7 % was observed under severe stress condition.

  12. A study on strengthening measures of non-proliferation regime through the export control system of sensitive materials, equipment and technology related to nuclear activities

    International Nuclear Information System (INIS)

    Kikuchi, Masahiro; Kurosawa, Mitsuru; Komizo, Yasuyoshi

    2004-01-01

    The strengthened safeguards caused from safeguards experiences to Iraq and DPRK leads to the expansion of the IAEA's activities for verification of all nuclear activities as well as verification of nuclear material in the States. The purpose of the activities, of course, includes detection of undeclared exports and imports of specified equipment and non-nuclear material. The Additional Protocol to the agreements between States and the IAEA for the application of safeguards requires to the States to declare the exports and imports information regarding specified equipment and non-nuclear material corresponding to the export control list that is established by the nuclear suppliers group. The Additional Protocol also insists the IAEA's right to access to the location identified by the State to resolve a question related to the declarations. Recently, the IAEA detected the black market group of the sensitive materials, equipment and technologies relevant to the nuclear proliferation through the safeguards activities to Iran and Libya. International community stated deeply concerns to the indecent facts. This paper would discuss and propose the supplemental strengthening measures of non-proliferation regime by effective combination of the safeguards activities under additional protocol and the export control regime. (author)

  13. Autonomia e relevância dos regimes The autonomy and relevance of regimes

    Directory of Open Access Journals (Sweden)

    Gustavo Seignemartin de Carvalho

    2005-12-01

    of norms and rules that create patterns of behavior and allow the convergence of the expectations of their participants in specific issue areas, in order to solve coordination problems that could lead to non-pareto-efficient outcomes. Considering that such definitions based merely on the "efficiency" of regimes do not seem to be sufficient to explain their effectiveness, the present article proposes a different definition for regimes: political arrangements that allow a redistribution of the gains of cooperation among the participants in certain issue areas, within an interdependence context. Regimes would thus be effective due to their autonomy and relevance - that is, due to their objective existence autonomously from their participants and their influence on the participants' behavior and expectations in ways that cannot be reduced to the individual action of any of them. This article begins with a brief discussion about terminological problems related to regime studies and with a definition of the concepts of autonomy and relevance. Then it classifies the authors that take part in this debate according to two distinct perspectives, one that denies (non-autonomists and the other that attributes (autonomists autonomy and relevance to regimes, briefly analyzing the authors and traditions that are more significant for this debate, focusing on autonomist authors and on arguments that back the hypothesis here presented. Finally, the article proposes an analytic decomposition of regimes into four main elements that give them autonomy and relevance: normativity, actors, specificity of the issue area and complex interdependence as context.

  14. Dune growth under multidirectional wind regimes

    Science.gov (United States)

    Gadal, C.; Rozier, O.; Claudin, P.; Courrech Du Pont, S.; Narteau, C.

    2017-12-01

    Under unidirectional wind regimes, flat sand beds become unstable to produce periodic linear dunes, commonly called transverse dunes because their main ridges are oriented perpendicular to the air flow. In areas of low sediment availability, the same interactions between flow, transport and topography produce barchan dunes, isolated sand-pile migrating over long distances with a characteristic crescentic shape. For the last fifteen years, barchan dunes and the instability at the origin of transverse dunes have been the subject of numerous studies that have identified a set of characteristic length and time scales with respect to the physical properties of both grains and fluid. This is not the case for dunes developing under multidirectional wind regimes. Under these conditions, dune orientation is measured with respect to the direction of the resultant sand flux. Depending on the wind regime, dunes do not always line up perpendicularly to the resultant sand flux, but can also be at an oblique angle or even parallel to it. These oblique and longitudinal dunes are ubiquitous in all deserts on Earth and planetary bodies because of the seasonal variability of wind orientation. They are however poorly constrained by observations and there is still no complete theoretical framework providing a description of their orientation and initial wavelength. Here, we extend the linear stability analysis of a flat sand of bed done in two dimensions for a unidirectional flow to three dimensions and multidirectional flow regimes. We are able to recover transitions from transverse to oblique or longitudinal dune patterns according to changes in wind regimes. We besides give a prediction for the initial dune wavelength. Our results compare well to previous theory of dune orientation and to field, experimental and numerical data.

  15. Deuteron structure in the deep inelastic regime

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Canal, C.A.; Tarutina, T. [Universidad Nacional de La Plata, IFLP/CONICET y Departamento de Fisica, La Plata (Argentina); Vento, V. [Universidad de Valencia-CSIC, Departamento de Fisica Teorica-IFIC, Burjassot (Valencia) (Spain)

    2017-06-15

    We study nuclear effects in the deuteron in the deep inelastic regime using the newest available data. We put special emphasis on their Q{sup 2} dependence. The study is carried out using a scheme which parameterizes, in a simple manner, these effects by changing the proton and neutron stucture functions in medium. The result of our analysis is compared with other recent proposals. We conclude that precise EMC ratios cannot be obtained without considering the nuclear effects in the deuteron. (orig.)

  16. On the regimes of premixing

    Energy Technology Data Exchange (ETDEWEB)

    Angelini, S.; Theofanous, T.G.; Yuen, W.W. [California Univ., Santa Barbara, CA (United States). Center for Risk Studies and Safety

    1998-01-01

    The conditions of the MAGICO-2000 experiment are extended to more broadly investigate the regimes of premixing, and the corresponding internal structures of mixing zones. With the help of the data and numerical simulations using the computer code PM-ALPHA, we can distinguish extremes of behavior dominated by inertia and thermal effects - we name these the inertia and thermal regimes, respectively. This is an important distinction that should guide future experiments aimed at code verification in this area. Interesting intermediate behaviors are also delineated and discussed. (author)

  17. Towards the geophysical regime in numerical dynamo models: studies of rapidly-rotating convection driven dynamos with low Pm and constant heat flux boundary conditions

    DEFF Research Database (Denmark)

    Sheyko, A.A.; Finlay, Chris; Marti, P.

    We present a set of numerical dynamo models with the convection strength varied by a factor of 30 and the ratio of magnetic to viscous diffusivities by a factor of 20 at rapid rotation rates (E =nu/(2 Omega d^2 ) = 10-6 and 10-7 ) using a heat flux outer BC. This regime has been little explored...... on the structure of the dynamos and how this changes in relation to the selection of control parameters, a comparison with the proposed rotating convection and dynamo scaling laws, energy spectra of steady solutions and inner core rotation rates. Magnetic field on the CMB. E=2.959*10-7, Ra=6591.0, Pm=0.05, Pr=1....

  18. Minorities, Legal Autonomy Regimes and the Principle of Non-discrimination: A Comparative Study on the Conflict of Civil Codes and the Personal Laws of Minorities

    Directory of Open Access Journals (Sweden)

    Kamran Hashemi Ardestani

    2009-03-01

    Full Text Available In international human rights law the application of the principle of ‘equality’ along with the ‘preservation of characteristics’ have been considered as the corner stones of a system for the protection of minorities. Regarding the ‘right of minorities to identity’ the regime of ‘personal legal autonomy’ will be of special interest to this study. While this phenomenon in non-Muslim countries is very rare, it is a common policy in the majority of Muslim countries. Despite the advantages of this regime, its discriminatory aspects stand in contrast with the main principle of human rights law, i.e. the principle of non-discrimination. This paper undertakes a comparative study of the legislation and legal practices of different states, in order to discern the ways that the conflicts of religious laws might affect the principle of non-discrimination. On the concept of non-discrimination the study makes a distinction between discrimination on the ground of religion and discrimination in religious rights. تجربه مسلمانان در زمینه حفظ هویت اقلیت‌ها برگرفته از حقوقی است که از دیرباز برای اقلیت‌های عمده مذهبی قائل شده‌اند که یکی از آنها پذیرش یک نوع خودمختاری ـ به ویژه خودمختاری قضایی‌ـ در برخی امور داخلی و نیز قوانین خانواده بوده است. این مقاله ضمن اینکه ارائه هرنوع خودمختاری قضایی به اقلیت‌ها را اصالتاً امری مثبت ارزیابی می‌نماید، آثار تبعیض‌آمیزی که ممکن است به هنگام پذیرش این نوع خودمختاری برای آنها در موارد تعارض بین قوانین مدنی کشور و یا قوانین مذهبی اکثریت با قوانین مربوطه اقلیت‌ها بروز نماید را به صورت

  19. Global regime shift dynamics of catastrophic sea urchin overgrazing

    Science.gov (United States)

    Ling, S. D.; Scheibling, R. E.; Rassweiler, A.; Johnson, C. R.; Shears, N.; Connell, S. D.; Salomon, A. K.; Norderhaug, K. M.; Pérez-Matus, A.; Hernández, J. C.; Clemente, S.; Blamey, L. K.; Hereu, B.; Ballesteros, E.; Sala, E.; Garrabou, J.; Cebrian, E.; Zabala, M.; Fujita, D.; Johnson, L. E.

    2015-01-01

    A pronounced, widespread and persistent regime shift among marine ecosystems is observable on temperate rocky reefs as a result of sea urchin overgrazing. Here, we empirically define regime-shift dynamics for this grazing system which transitions between productive macroalgal beds and impoverished urchin barrens. Catastrophic in nature, urchin overgrazing in a well-studied Australian system demonstrates a discontinuous regime shift, which is of particular management concern as recovery of desirable macroalgal beds requires reducing grazers to well below the initial threshold of overgrazing. Generality of this regime-shift dynamic is explored across 13 rocky reef systems (spanning 11 different regions from both hemispheres) by compiling available survey data (totalling 10 901 quadrats surveyed in situ) plus experimental regime-shift responses (observed during a total of 57 in situ manipulations). The emergent and globally coherent pattern shows urchin grazing to cause a discontinuous ‘catastrophic’ regime shift, with hysteresis effect of approximately one order of magnitude in urchin biomass between critical thresholds of overgrazing and recovery. Different life-history traits appear to create asymmetry in the pace of overgrazing versus recovery. Once shifted, strong feedback mechanisms provide resilience for each alternative state thus defining the catastrophic nature of this regime shift. Importantly, human-derived stressors can act to erode resilience of desirable macroalgal beds while strengthening resilience of urchin barrens, thus exacerbating the risk, spatial extent and irreversibility of an unwanted regime shift for marine ecosystems.

  20. How Welfare Regimes Generate and Erode Social Capital

    DEFF Research Database (Denmark)

    Larsen, Christian Albrekt

    2007-01-01

    in the USA and other liberal welfare regimes, while social capital is stable in the so-called social democratic and conservative welfare regimes. The second puzzle is why the group of social democratic regimes have extremely high levels of social trust. It is argued that both puzzles have to do......Comparative studies of social capital, operationalised as social trust between citizens, have revealed two major puzzles. The first puzzle has to do with the decline in social trust in the USA, which fuelled considerable debate about social capital. The question is why social capital erodes...... with the presence or absence of a poor and culturally distinct underclass. The social democratic welfare regimes hinder – while the liberal welfare regime generate – such underclass phenomena....

  1. Land degradation and property regimes

    Science.gov (United States)

    Paul M. Beaumont; Robert T. Walker

    1996-01-01

    This paper addresses the relationship between property regimes and land degradation outcomes, in the context of peasant agriculture. We consider explicitly whether private property provides for superior soil resource conservation, as compared to common property and open access. To assess this we implement optimization algorithms on a supercomputer to address resource...

  2. Regime identification in ASDEX Upgrade

    International Nuclear Information System (INIS)

    Giannone, L; Sips, A C C; Kardaun, O; Spreitler, F; Suttrop, W

    2004-01-01

    The ability to recognize the transition from the L-mode to the H-mode or from the H-mode to the improved H-mode reliably from a conveniently small number of measurements in real time is of increasing importance for machine control. Discriminant analysis has been applied to regime identification of plasma discharges in the ASDEX Upgrade tokamak. An observation consists of a set of plasma parameters averaged over a time slice in a discharge. The data set consists of all observations over different discharges and time slices. Discriminant analysis yields coefficients allowing the classification of a new observation. The results of a frequentist and a formal Bayesian approach to discriminant analysis are compared. With five plasma variables, a failure rate of 1.3% for predicting the L-mode and the H-mode confinement regime was achieved. With five plasma variables, a failure rate of 5.3% for predicting the H-mode and the improved H-mode confinement regime was achieved. The coefficients derived by discriminant analysis have been applied subsequently to discharges to illustrate the operation of regime identification in a real time control system

  3. Monetary regimes in open economies

    NARCIS (Netherlands)

    Korpos, A.

    2006-01-01

    This thesis presents a two-country open economy framework for the analysis of strategic interactions among monetary authorities and wage bargaining institutions. From this perspective, the thesis investigates the economic consequences of replacing flexible and fixed exchange rate regimes with a

  4. Resource Windfalls, Political Regimes, and Political Stability

    OpenAIRE

    Francesco Caselli; Andrea Tesei

    2011-01-01

    We study theoretically and empirically whether natural resource windfalls affect political regimes. We document the following regularities. Natural resource windfalls have no effect on the political system when they occur in democracies. However, windfalls have significant political consequences in autocracies. In particular, when an autocratic country receives a positive shock to its flow of resource rents it responds by becoming even more autocratic. Furthermore, there is heterogeneity in t...

  5. Discrete ordinates solution of coupled conductive radiative heat transfer in a two-layer slab with Fresnel interfaces subject to diffuse and obliquely collimated irradiation

    International Nuclear Information System (INIS)

    Muresan, Cristian; Vaillon, Rodolphe; Menezo, Christophe; Morlot, Rodolphe

    2004-01-01

    The coupled conductive radiative heat transfer in a two-layer slab with Fresnel interfaces subject to diffuse and obliquely collimated irradiation is solved. The collimated and diffuse components problems are treated separately. The solution for diffuse radiation is obtained by using a composite discrete ordinates method and includes the development of adaptive directional quadratures to overcome the difficulties usually encountered at the interfaces. The complete radiation numerical model is validated against the predictions obtained by using the Monte Carlo method

  6. Sensitivity analysis with regard to variations of physical forcing including two possible future hydrographic regimes for the Oeregrundsgrepen. A follow-up baroclinic 3D-model study

    International Nuclear Information System (INIS)

    Engqvist, A.; Andrejev, O.

    2000-02-01

    A sensitivity analysis with regard to variations of physical forcing has been performed using a 3D baroclinic model of the Oeregrundsgrepen area for a whole-year period with data pertaining to 1992. The results of these variations are compared to a nominal run with unaltered physical forcing. This nominal simulation is based on the experience gained in an earlier whole-year modelling of the same area; the difference is mainly that the present nominal simulation is run with identical parameters for the whole year. From a computational economy point of view it has been necessary to vary the time step between the month-long simulation periods. For all simulations with varied forcing, the same time step as for the nominal run has been used. The analysis also comprises the water turnover of a hypsographically defined subsection, the Bio Model area, located above the SFR depository. The external forcing factors that have been varied are the following (with their found relative impact on the volume average of the retention time of the Bio Model area over one year given within parentheses): atmospheric temperature increased/reduced by 2.5 deg C (-0.1% resp. +0.6%), local freshwater discharge rate doubled/halved (-1.6% resp. +0.01%), salinity range at the border increased/reduced a factor 2 (-0.84% resp. 0.00%), wind speed forcing reduced 10% (+8.6%). The results of these simulations, at least the yearly averages, permit a reasonably direct physical explanation, while the detailed dynamics is for natural reasons more intricate. Two additional full-year simulations of possible future hydrographic regimes have also been performed. The first mimics a hypothetical situation with permanent ice cover, which increases the average retention time 87%. The second regime entails the future hypsography with its anticipated shoreline displacement by an 11 m land-rise in the year 4000 AD, which also considerably increases the average retention times for the two remaining layers of the

  7. Impacts of Exchange Rate Regime Choice on Macroeconomic Performance in Emerging Markets

    Directory of Open Access Journals (Sweden)

    Rüstem Yanar

    2008-12-01

    Full Text Available This paper investigates the impact of exchange rate regime choice on macroeconomic performance after Bretton Woods in emerging market countries. It is studied especially inflation, growth and financial crises. It’s found that for emerging market countries, fixed regimes are associated with lower inflation than floats. On growth effect of exchange rate regime choice is not same all period. Fixed regimes are associated with faster growth but after 1990 fixed regimes brought about slower growth. At the same time, fixed exchange rate regimes are associated with financial fragility after 1990 in emerging markets

  8. Private actor accountability on international regimes

    Directory of Open Access Journals (Sweden)

    Wahyudi Purnomo

    2017-12-01

    Full Text Available Public-Private Partnerships (PPPs have emerged along with the growing role of corporations in global development. One of the largest forms of PPP today is the UN Global Compact. The UN Global Compact involves of companies, NGOs, IGOs and state governments. All of them are trying to realize globalization with a more humanist face with attention to the protection of human rights, environment, labor standards and anti-corruption. Engaging private actors in global governance, The UN Global Compact raises many issues such as power, authority, and legitimacy. The effort to tackle it all is to increase PPP accountability. This research seeks to describe what efforts can be made to enhance private accountability within the international regime. The research undertaken is a descriptive study, focuses on public-private partnerships in the UN Global Compact regime. The study found that there were two attempts that could be done. First, by involving the stakeholders in the development of procedures, mechanisms, reporting and monitoring associated with trying to improve the company’s reputation. Second, by looking at corporate relations as agent and UN Global Compact as principal in principal-agent relation in the international regime.

  9. Achievable rate of spectrum sharing cognitive radio systems over fading channels at low-power regime

    KAUST Repository

    Sboui, Lokman; Rezki, Zouheir; Alouini, Mohamed-Slim

    2014-01-01

    the previously achieved rate at the low-power regime. Interestingly, we show that the low-power regime analysis provides a specific insight into the maximum achievable rate behavior of CR that has not been reported by previous studies.

  10. Increasingly Equalized? A Study of Part-Time Work in ‘Old’ and ‘New’ Part-Time Work Regimes

    Directory of Open Access Journals (Sweden)

    Heidi Nicolaisen

    2011-01-01

    Full Text Available Recent debates on equalization of part-time work alongside full-time work stress the importance of high quality part-time jobs. This paper compares equalization in banking in three countries: two `old´ part-time work regimes, Norway and Sweden, and Ireland, where part-time work started to increase more recently. Banking is particularly interesting as a sector with a high proportion of female employment and good working conditions. One main interest is the role of regulations and how they are enforced at company level. The analysis shows that part-time work in the Nordic countries is normalized in terms of access and general work conditions, while in Ireland access is more restricted. Career opportunities are, however, restricted in all three countries. This paper argues that further equalization may be hindered by `soft´ regulations and a gradual normalization process that also normalizes disadvantages associated with part-time work and the category of the `working mother´.

  11. Comparative study of the expansion dynamics of laser-driven plasma and shock wave in in-air and underwater ablation regimes

    Science.gov (United States)

    Nguyen, Thao T. P.; Tanabe, Rie; Ito, Yoshiro

    2018-03-01

    We compared the expansion characteristics of the plasma plumes and shock waves generated in laser-induced shock process between the two ablation regimes: in air and under water. The observation was made from the initial moment when the laser pulse hit the target until 1.5 μs. The shock processes were driven by focusing a single laser pulse (1064 nm, FWHM = 13 ns) onto the surface of epoxy-resin blocks using a 40-mm focal length lens. The estimated laser intensity at the target plane is approximate to 9 ×109Wcm-2 . We used the fast-imaging technique to observe the expansion of the plasma plume and a custom-designed time-resolved photoelasticity imaging technique to observe the propagation of shock waves with the time resolution of nanoseconds. We found that at the same intensity of the laser beam, the plasma expansion during the laser pulse follows different mechanisms: the plasma plume that grows in air follows a radiation-wave model while a detonation-wave model can explain the expansion of the plasma plume induced in water. The ideal blast wave theory can be used to predict the decay of the shock wave in air but is not appropriate to describe the decay of the shock wave induced under water.

  12. The Public Opinion participation in the Nuclear Facilities Licensing Regime: A study for The Egyptian Nuclear Law and other countries laws

    International Nuclear Information System (INIS)

    Ali, A. M.; Abd El-Moniem, A. E.

    2012-12-01

    This paper deals with the Nuclear Facilities Licensing Regime and the public Opinion participation. It discusses the general conceptual framework such as the importance of public opinion in the licensing process for nuclear facilities. It deals with the transparency principle and the nuclear safety. It also an analysis the Egyptian nuclear law for regulating the nuclear and radiological activities(law No.7) and its provisions that regulate the participation of the public in the licensing process (Article No.12 paragraph No.7 and 16 ) that staled that the regulatory body will set the regulation to involve the public in the licensing and it will also issues publicly a garrulity report about the nuclear safety situation in the state. It also deals with the legal rules for licensing and the participation of public in it many states such as Japan, France and Germany. The paper concluded that the lunch of a nuclear programme should lunch, in parallel, a programme for the public communications because in the absent of such a public programme, the political decisions of nuclear programme might be lose its effectiveness and the programme might be slow dow. (Author)

  13. Transient regimes in a heavy water reactor; Regimes transitoires dans un reacteur a eau lourde

    Energy Technology Data Exchange (ETDEWEB)

    Raievski, V [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1953-07-01

    We studied the variations of power and reactivity of a reactor when we raise in a continuous way the starting plates. During the subcritical regime (negative reactivity), the power is determined by reactivity and by the intensity of the sources of photo neutrons, produced during the previous work of the reactor. When, during the rise of the plates, the reactor, pass by the critical regime (zero reactivity), one notes that the reached power is independent of the initial reactivity. During the sur-critical regime (positive reactivity), the elevation of temperature of the uranium bars slows down the growth of reactivity due to the movements of the plates. The power stretches then toward a value that depends only on the regime of cooling of the reactor and the excess of the available reactivity. This survey permits to choose such a rise speed, that reactivity remains constantly lower to a value beyond which the piloting of the reactor becomes difficult. This result is not more valid, if the intensity of the sources is insufficient, what takes place during the first divergences and after a stop of long length. (author) [French] On etudie les variations de puissance et de reactivite d'un reacteur quand on leve d'une facon continue les plaques de demarrage. Pendant le regime subcritique (reactivite negative), la puissance est determinee par la reactivite et par l'intensite des sources de photoneutrons, produites pendant la marche anterieure du reacteur. Quand, au cours de la montee des plaques, le reacteur passe par le regime critique (reactivite nulle), on constate que la puissance atteinte est independante de la reactivite initiale. Pendant le regime surcritique (reactivite positive), l'elevation de temperature des barres d'uranium ralentit l'accroissement de reactivite due aux mouvements des plaques. La puissance tend alors vers une valeur qui ne depend plus que du regime de refroidissement du reacteur et de l'exces de la reactivite disponible. Cette etude permet de

  14. Exchange rate regimes and monetary arrangements

    Directory of Open Access Journals (Sweden)

    Ivan Ribnikar

    2005-06-01

    Full Text Available There is a close relationship between a country’s exchange rate regime and monetary arrangement and if we are to examine monetary arrangements then exchange rate regimes must first be analysed. Within the conventional and most widely used classification of exchange rate regimes into rigid and flexible or into polar regimes (hard peg and float on one side, and intermediate regimes on the other there, is a much greater variety among intermediate regimes. A more precise and, as will be seen, more useful classification of exchange rate regimes is the first topic of the paper. The second topic is how exchange rate regimes influence or determine monetary arrangements and monetary policy or monetary policy regimes: monetary autonomy versus monetary nonautonomy and discretion in monetary policy versus commitment in monetary policy. Both topics are important for countries on their path to the EU and the euro area

  15. ACCESSORIES OF FISCAL OBLIGATION. LEGAL REGIME

    Directory of Open Access Journals (Sweden)

    RADA POSTOLACHE

    2012-05-01

    Full Text Available The interest – which is an institution typical to private law, has been taken over by the fiscal field and adapted to the specific features of fiscal obligation – being defined by its imperative legal regime, which has at the least the following characteristic elements: unitary character, imposed legal percentage, compulsory demand of interest, automatic application. In order to render responsible fiscal debtors, the lawmaker has reintroduced, as an accessory of fiscal obligation, delayed payment penalties, which have a distinct nature and legal regime, but without the principle non bis in idem being transgressed. Our study aims to establish the legal regime ofaccessories typical to fiscal obligation, from the perspective of special normative acts, but also of the common law within the field – Civil Code and Government Ordinance No. 13/2011 – by pointing out at the same time both the particular circumstances and procedural ones regulated by the Fiscal Procedure Code, shedding light upon the controversial legal nature of accessories.

  16. On the radiative transfer problem in a spherical medium subject to Fresnel's reflective boundary conditions

    International Nuclear Information System (INIS)

    Mohammed, M.H.H.

    2012-01-01

    Radiation transfer problem for anisotropic scattering in a spherical homogeneous, turbid medium with angular dependent (specular) and diffuse reflecting boundary is considered. The angular dependent reflectivity of the boundary is considered as Fresnel's reflection probability function. The solution of the problem containing an energy source in a medium of specular and diffuse reflecting boundaries is given in terms of the solution of the source-free problem. The source-free problem for anisotropic scattering through a homogeneous solid sphere and two concentric spheres is solved by using the Pomraning- Eddington approximation method. This method transform the integro-differential equation into two differential equations for the radiance g (x) and net flux q (x) which has an analytical solution in terms of the modified Bessel function. Two different weight functions are used to verify the boundary conditions and so, find the solution constants. The partial heat fluxes at the boundaries of a solid sphere and spherical shell of transparent and reflecting boundaries are calculated. The media are taken with or without internal black-body radiation. The calculations are carried out for various values of refractive index and different radii. The results are compared with those of the Galerkin technique

  17. Single-beam image encryption using spatially separated ciphertexts based on interference principle in the Fresnel domain

    Science.gov (United States)

    Wang, Qu; Guo, Qing; Lei, Liang; Zhou, Jinyun

    2014-12-01

    A new optical security system for image encryption based on optical interference principle and translation property of Fresnel transform (FrT) has been proposed in this article. The algorithm of this proposal is specially designed for single-beam optical decryption and can thoroughly resolve the silhouette problem existing in the previous interference-based scheme. Different from earlier schemes using interference of phase-only masks (POMs), the inverse FrT of primitive image is digitally decomposed into a random POM and a complex field distribution. Information associated with the primitive images can be completely smoothed away by the modulation of this random POM. Through the translation property of FrT, two linear phase-only terms are then used to modulate the obtained random POM and the complex distribution, respectively. Two complex ciphertexts are generated by performing digital inverse FrT again. One cannot recover any visible information of secret image using only one ciphertext. Moreover, to recover the primitive image correctly, the correct ciphertexts must be placed in the certain positions of input plane of decryption system, respectively. As additional keys, position center coordinates of ciphertexts can increase the security strength of this encryption system against brute force attacks greatly. Numerical simulations have been given to verify the performance and feasibility of this proposal. To further enhance the application value of this algorithm, an alternative approach based on Fourier transform has also been discussed briefly.

  18. Band structure of one-dimensional doped photonic crystal with three level atoms using the Fresnel coefficients method

    Science.gov (United States)

    Jafari, A.; Rahmat, A.; Bakkeshizadeh, S.

    2018-01-01

    We consider a one-dimensional photonic crystal (1DPC) composed of double-layered dielectrics. Electric permittivity and magnetic permeability of this crystal depends on the incident electromagnetic wave frequency. We suppose that three level atoms have been added to the second layer of each dielectric and this photonic crystal (PC) has been doped. These atoms can be added to the layer with different rates. In this paper, we have calculated and compared the band structure of the mentioned PC considering the effect of added atoms to the second layer with different rates through the Fresnel coefficients method. We find out that according to the effective medium theory, the electric permittivity of the second layer changes. Also the band structure of PC for both TE and TM polarizations changes, too. The width of bandgaps related to “zero averaged refractive index” and “Bragg” increases. Moreover, new gap branches appear in new frequencies at both TE and TM polarizations. In specific state, two branches of “zero permittivity” gap appear in the PC band structure related to TM polarization. With increasing the amount of the filling rate of total volume with three level atoms, we observe a lot of changes in the PC band structure.

  19. Numerically correcting the joint misplacement of the sub-holograms in spatial synthetic aperture digital Fresnel holography.

    Science.gov (United States)

    Jiang, Hongzhen; Zhao, Jianlin; Di, Jianglei; Qin, Chuan

    2009-10-12

    We propose an effective reconstruction method for correcting the joint misplacement of the sub-holograms caused by the displacement error of CCD in spatial synthetic aperture digital Fresnel holography. For every two adjacent sub-holograms along the motion path of CCD, we reconstruct the corresponding holographic images under different joint distances between the sub-holograms and then find out the accurate joint distance by evaluating the quality of the corresponding synthetic reconstructed images. Then the accurate relative position relationships of the sub-holograms can be confirmed according to all of the identified joint distances, with which the accurate synthetic reconstructed image can be obtained by superposing the reconstruction results of the sub-holograms. The numerical reconstruction results are in agreement with the theoretical analysis. Compared with the traditional reconstruction method, this method could be used to not only correct the joint misplacement of the sub-holograms without the limitation of the actually overlapping circumstances of the adjacent sub-holograms, but also make the joint precision of the sub-holograms reach sub-pixel accuracy.

  20. [Heath and political regimes: presidential or parliamentary government for Colombia?].

    Science.gov (United States)

    Idrovo, Alvaro J

    2007-01-01

    Changing the presidential regime for a parliamentarian one is currently be-ing discussed in Colombia. This preliminary study explores the potential effects on health of both presidential and parliamentary regimes by using world-wide data. An ecological study was undertaken using countries from which comparable information concerning life-expectancy at birth, political regime, economic development, inequality in income, social capital (as measured by general-ised trust or Corruption Perceptions Index), political rights, civil freedom and cultural diversity could be obtained. Life-expectancy at birth and macro-determinants were compared between both political regimes. The co-relationship between these macro-determinants was estimated and the relationship between political regimen and life-expectancy at birth was estimated using robust regression. Crude analysis revealed that parliamentary countries have greater life-expectancy at birth than countries having a presidential regime. Significant co-relationships between all macro-determinants were observed. No differential effects were observed between both political regimes regarding life-expectancy at birth in multiple robust regressions. There is no evidence that presidential or parliamentary regimes provide greater levels of health for the population. It is suggested that public health policies be focused on other macro-determinants having more known effects on health, such as income inequality.

  1. Detecting spatial regimes in ecosystems

    Science.gov (United States)

    Sundstrom, Shana M.; Eason, Tarsha; Nelson, R. John; Angeler, David G.; Barichievy, Chris; Garmestani, Ahjond S.; Graham, Nicholas A.J.; Granholm, Dean; Gunderson, Lance; Knutson, Melinda; Nash, Kirsty L.; Spanbauer, Trisha; Stow, Craig A.; Allen, Craig R.

    2017-01-01

    Research on early warning indicators has generally focused on assessing temporal transitions with limited application of these methods to detecting spatial regimes. Traditional spatial boundary detection procedures that result in ecoregion maps are typically based on ecological potential (i.e. potential vegetation), and often fail to account for ongoing changes due to stressors such as land use change and climate change and their effects on plant and animal communities. We use Fisher information, an information theory-based method, on both terrestrial and aquatic animal data (U.S. Breeding Bird Survey and marine zooplankton) to identify ecological boundaries, and compare our results to traditional early warning indicators, conventional ecoregion maps and multivariate analyses such as nMDS and cluster analysis. We successfully detected spatial regimes and transitions in both terrestrial and aquatic systems using Fisher information. Furthermore, Fisher information provided explicit spatial information about community change that is absent from other multivariate approaches. Our results suggest that defining spatial regimes based on animal communities may better reflect ecological reality than do traditional ecoregion maps, especially in our current era of rapid and unpredictable ecological change.

  2. Cloud regimes as phase transitions

    Science.gov (United States)

    Stechmann, Samuel; Hottovy, Scott

    2017-11-01

    Clouds are repeatedly identified as a leading source of uncertainty in future climate predictions. Of particular importance are stratocumulus clouds, which can appear as either (i) closed cells that reflect solar radiation back to space or (ii) open cells that allow solar radiation to reach the Earth's surface. Here we show that these clouds regimes - open versus closed cells - fit the paradigm of a phase transition. In addition, this paradigm characterizes pockets of open cells (POCs) as the interface between the open- and closed-cell regimes, and it identifies shallow cumulus clouds as a regime of higher variability. This behavior can be understood using an idealized model for the dynamics of atmospheric water as a stochastic diffusion process. Similar viewpoints of deep convection and self-organized criticality will also be discussed. With these new conceptual viewpoints, ideas from statistical mechanics could potentially be used for understanding uncertainties related to clouds in the climate system and climate predictions. The research of S.N.S. is partially supported by a Sloan Research Fellowship, ONR Young Investigator Award N00014-12-1-0744, and ONR MURI Grant N00014-12-1-0912.

  3. The study of a NaK-water exchanger in steady and transient states (1962); Etude d'un echangeur NaK-eau en regimes permanents et transitoires (1962)

    Energy Technology Data Exchange (ETDEWEB)

    List, D; Schwab, B [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    During this study on a NaK-water exchanger, it was desired to know the temperature variations, in the transient states, along the metallic wall separating the two fluids. The basic equations, which are partial differential equations, are established and are then transformed into a differential equation system for which the various coefficients are calculated. These equations, after certain modifications, can be set up on an analogic computer and the exchanger behaviour can then be studied. The steady states of the exchanger are studied first and it is then submitted to various types of perturbations. (authors) [French] Au cours de cette etude, sur un echangeur NaK-eau, on desire connaitre l'evolution, en regimes transitoires, des temperatures le long de la paroi metallique separant les deux fluides. Apres avoir pose les equations de base, equations aux derivees partielles, on les transforme en un systeme d'equations differentielles pour lequel on calcule les divers coefficients. Ces equations peuvent alors, apres certaines modifications, etre simulees sur machine analogique, ce qui permet d'observer le comportement de l'echangeur. On etudie en premier lieu les regimes permanents de l'echangeur, puis on soumet celui-ci a differents types de perturbations. (auteurs)

  4. Flow regimes in vertical gas-solid contact systems

    Energy Technology Data Exchange (ETDEWEB)

    Yerushalmi, J.; Cankurt, N. T.; Geldart, D.; Liss, B.

    1976-01-01

    The flow characteristics in fluidized beds, i.e., gas-solid systems, was studied to determine the flow regimes, the interaction of gas and solid in the various flow regimes and the dependence of this interaction and of transition between flow regimes on the properties of the gas and solid, on the gas and solid flow rates, and on the containing vessel. Fluidized beds with both coarse and fine particles are considered. Test results using high speed photography to view the operation of a 2-dimensional bed are discussed. (LCL)

  5. Regimes of Two-Phase Flow in Short Rectangular Channel

    Science.gov (United States)

    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.

  6. An Examination of the Nature of Global MODIS Cloud Regimes

    Science.gov (United States)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin; Kato, Seiji; Huffman, George J.

    2014-01-01

    We introduce global cloud regimes (previously also referred to as "weather states") derived from cloud retrievals that use measurements by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the Aqua and Terra satellites. The regimes are obtained by applying clustering analysis on joint histograms of retrieved cloud top pressure and cloud optical thickness. By employing a compositing approach on data sets from satellites and other sources, we examine regime structural and thermodynamical characteristics. We establish that the MODIS cloud regimes tend to form in distinct dynamical and thermodynamical environments and have diverse profiles of cloud fraction and water content. When compositing radiative fluxes from the Clouds and the Earth's Radiant Energy System instrument and surface precipitation from the Global Precipitation Climatology Project, we find that regimes with a radiative warming effect on the atmosphere also produce the largest implied latent heat. Taken as a whole, the results of the study corroborate the usefulness of the cloud regime concept, reaffirm the fundamental nature of the regimes as appropriate building blocks for cloud system classification, clarify their association with standard cloud types, and underscore their distinct radiative and hydrological signatures.

  7. Asset allocation and regime switching on Croatian financial market

    Directory of Open Access Journals (Sweden)

    Tihana Škrinjarić

    2016-12-01

    Full Text Available It has been known for quite some time now that financial markets exhibit changes in regimes over time. A majority of the literature tends to support that financial markets undergo regimes of bull and bear markets. This characteristic should be modeled in a proper way as investors are always interested in beating the market: either by achieving better returns than others, or by minimizing their portfolio risks. There exist many mathematical and statistical models that are used as tools to achieve the mentioned goals. Introducing the regime switching methodology in existing models has proven to be facilitate achieving such goals. Therefore, the objective of this study is to utilize the regime switching methodology on the Croatian financial market to ascertain its usefulness for Croatian investors. Multivariate regime switching and non-switching models were estimated using daily data from the period 2 January 2007 to 31 December 2015. The assumption is that the investor is interested in stock and bond markets. The results from the MGARCH and regime switching MGARCH models are then compared in order to give answers as to whether the respective methodology applied to the Croatian market is useful and how it may benefit investors. Most of the results support the presumption of incorporating this particular methodology in financial modeling for the Croatia markets. This is the first research that applies the regime switching MGARCH methodology in Croatia (including the Balkan region, hence we expect that this will be a significant contribution to existing methodologies in literature.

  8. Thermal power generation and the environment. I. Hydrothermal and hydrochemical regime studies of the cooling reservoir of the Lithuanian SSR Central Steam Power Station. Teploenergetika i okruzhayushchaya sreda i gidrotermicheskii i gidrokhinicheskii rezhim vodokhranilishcha okhzaditelya intovskoi gres

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

    Studies were of the physico-geographical conditions (relief, soil, vegetation, etc.) of a water-collection basin and their effect on the processes taking place in a reservoir. An analysis is made of the elements that make up the input and outflow segments of a reservoir's water balance, particularly the evaporation of heated waters from the surface of the reservoir. Data are given on long-term measurements of the thermal regime of a reservoir-coolant, heat-exchange processes and their connection with the efficient operation of a thermal power station. The thermal balance of a reservoir is defined. A study was made of the effect that the Lithuaniam central power steam station has on atmospheric sediments, the physico-chemical regime of the reservoir-coolant, river drainage, and ground water. A description is given of the chemical composition of the surface bottom deposits, the intensity of modern sedimentation processes and sediment accumulation in the reservoir. 126 references, 70 figures, 36 tables.

  9. Stochastic dynamical models for ecological regime shifts

    DEFF Research Database (Denmark)

    Møller, Jan Kloppenborg; Carstensen, Jacob; Madsen, Henrik

    the physical and biological knowledge of the system, and nonlinearities introduced here can generate regime shifts or enhance the probability of regime shifts in the case of stochastic models, typically characterized by a threshold value for the known driver. A simple model for light competition between...... definition and stability of regimes become less subtle. Ecological regime shifts and their modeling must be viewed in a probabilistic manner, particularly if such model results are to be used in ecosystem management....

  10. Estudos sobre o regime de competência no setor público brasileiro: os desencontros da discussão acadêmica = Accrual basis in Brazilian public sector studies: the mismatches of Academic discussion

    Directory of Open Access Journals (Sweden)

    Neuton Alcedir de Lima Amaral Amaral

    2014-12-01

    Full Text Available As pesquisas sobre a adoção do regime de competência pelo setor público no Brasil são poucas e incipientes, o que é de se esperar devido à escassez de casos reais para estudo, pois a maioria dos entes federativos ainda não adotou o regime de competência de forma integral. Apesar disso, representam o estado da arte do conhecimento científico no assunto e esta pesquisa buscou identificar as contribuições da academia para a compreensão do regime de competência aplicado ao setor público no Brasil, por meio de uma revisão crítica dos estudos nacionais que tratam do tema. Foram selecionados os artigos que abordam o tema regime de competência no setor público, publicados de 2005-2012 em eventos e periódicos pontuados pela Capes, e que estão relacionados com contabilidade e/ou contabilidade pública. Os resultados indicam que não existe uma tendência definida de linhas de pesquisa e os achados de um estudo não costumam ser comparados com outros. As pesquisas não são levadas adiante, nem por outros autores, nem pelos próprios, e os autores não exploram lacunas deixadas por pesquisas anteriores, sejam elas nacionais ou estrangeiras. As comparações entre os estudos também são prejudicadas, em alguns casos, devido a fragilidades metodológicas. Com isso, as contribuições da academia para a compreensão do regime de competência aplicado ao setor público são bastante fragmentadas, o que pode tornar lento o avanço do tema. The research on the adoption of accrual basis by the public sector in Brazil are few and fledgling, what is expected due to the scarcity of real study cases, because most federal entities have not adopted the accrual basis in it integral form yet. Despite of this, existing research represent the state-of-art of scientific knowledge on the subject and this research has sought to identify the Academy contributions to the understanding of accrual basis applied to the public sector in Brazil through a review

  11. Alberta oil sands royalty regime

    International Nuclear Information System (INIS)

    Asgarpour, S.

    2004-01-01

    The long term objective of the Oil Sands Business Unit of Alberta Energy is to pave the way for Alberta's bitumen production to reach 3 million barrels per day by 2020. This presentation described the national government's role in resource development. It was emphasized that since the Crown is the owner of the oil sands resource, it would benefit by providing strategic leadership and by generating a larger royalty base. The oil sands fiscal regime was described with reference to generic royalty, risk sharing, investment, and project economics. Business rule principles were also outlined along with criteria for project expansions. Both upstream and downstream challenges and opportunities were listed. 4 figs

  12. Accountability Challenges in the Transnational Regime Complex for Climate Change

    OpenAIRE

    Widerberg, O.E.; Pattberg, P.H.

    2017-01-01

    This article discusses challenges to accountability in the context of transnational climate governance. It argues that the emergence of a distinct transnational regime complex and the increasingly integrated structure of international and transnational climate governance create new challenges for using established analytical frameworks that rely on accountability regimes for individual actor types. Instead, studying accountability requires a system-level conceptualization and a revisiting of ...

  13. Study of electronic field emission from large surfaces under static operating conditions and hyper-frequency; Etude de l'emision electronique par effet de champ sur des surfaces larges en regime statique et hyperfrequence

    Energy Technology Data Exchange (ETDEWEB)

    Luong, M

    1997-09-01

    The enhanced electronic field emission from large area metallic surfaces lowers performances of industrial devices that have to sustain high electric field under vacuum. Despite of numerous investigations in the past, the mechanisms of such an emission have never been well clarified. Recently, research in our laboratory has pointed out the importance played by conducting sites (particles and protrusions). A refined geometrical model, called superposed protrusions model has been proposed to explain the enhanced emission by local field enhancement. As a logical continuation, the present work aims at testing this model and, in the same time, investigating the means to suppress the emission where it is undesirable. Thus, we have showed: the cause of current fluctuations in a continuous field regime (DC), the identity of emission characteristics ({beta}, A{sub e}) in both radiofrequency (RF) and DC regimes, the effectiveness of a thermal treatment by extern high density electronic bombardment, the effectiveness of a mechanical treatment by high pressure rinsing with ultra pure water, the mechanisms and limits of an in situ RF processing. Furthermore, the electronic emission from insulating particles has also been studied concurrently with a spectral analysis of the associated luminous emission. Finally, the refined geometrical model for conducting sites is reinforced while another model is proposed for some insulating sites. Several emission suppressing treatments has been explored and validated. At last, the characteristic of a RF pulsed field emitted electron beam has been checked for the first time as a possible application of such a field emission. (author)

  14. Study of electronic field emission from large surfaces under static operating conditions and hyper-frequency; Etude de l'emision electronique par effet de champ sur des surfaces larges en regime statique et hyperfrequence

    Energy Technology Data Exchange (ETDEWEB)

    Luong, M

    1997-09-01

    The enhanced electronic field emission from large area metallic surfaces lowers performances of industrial devices that have to sustain high electric field under vacuum. Despite of numerous investigations in the past, the mechanisms of such an emission have never been well clarified. Recently, research in our laboratory has pointed out the importance played by conducting sites (particles and protrusions). A refined geometrical model, called superposed protrusions model has been proposed to explain the enhanced emission by local field enhancement. As a logical continuation, the present work aims at testing this model and, in the same time, investigating the means to suppress the emission where it is undesirable. Thus, we have showed: the cause of current fluctuations in a continuous field regime (DC), the identity of emission characteristics ({beta}, A{sub e}) in both radiofrequency (RF) and DC regimes, the effectiveness of a thermal treatment by extern high density electronic bombardment, the effectiveness of a mechanical treatment by high pressure rinsing with ultra pure water, the mechanisms and limits of an in situ RF processing. Furthermore, the electronic emission from insulating particles has also been studied concurrently with a spectral analysis of the associated luminous emission. Finally, the refined geometrical model for conducting sites is reinforced while another model is proposed for some insulating sites. Several emission suppressing treatments has been explored and validated. At last, the characteristic of a RF pulsed field emitted electron beam has been checked for the first time as a possible application of such a field emission. (author)

  15. REGIME SWITCHING DETERMINANTS OF SOVEREIGN CDS SPREADS: EVIDENCE FROM TURKEY

    Directory of Open Access Journals (Sweden)

    Umurcan Polat

    2017-12-01

    Full Text Available In this study, it is assessed the main determinants of sovereign CDS spreads in Turkey from January 2006 to December 2015. Before delving into the nonlinear Markov regime-switching model estimation, a conventional one-state linear model is estimated answering to what extent the sovereign credit risk is affected in between global and country-specific market variables and by credit ratings announcement changes. In broad strokes, the regime-switching analysis reveals that among domestic variables, it is the foreign exchange rate that affects the sovereign credit risk more in more volatile periods and among global variables, the indicators standing for global volatility risk premiums and international liquidity primarily influence the changes in the sovereign CDS spread in turbulent regimes whereas proxies for global risk free rate are significant more in tranquil regimes.

  16. Measuring the effectiveness of international environmental regimes

    Energy Technology Data Exchange (ETDEWEB)

    Helm, C.; Sprinz, D.F.

    1999-05-01

    While past research has emphasized the importance of international regimes for international governance, systematic assessments of regime effects are missing. This article derives a standardized measurement concept for the effectiveness of international environmental regimes by developing an operational rational choice calculus to evaluate actual policy simultaneously against a non-regime counterfactual and a collective optimum. Subsequently, the empirical feasibility of the measurement instrument is demonstrated by way of two international treaties regulating transboundary air pollution in Europe. The results demonstrate that the regimes indeed show positive effects - but fall substantially short of the collective optima. (orig.)

  17. Sensitivity to spatial and temporal scale and fire regime inputs in deriving fire regime condition class

    Science.gov (United States)

    Linda Tedrow; Wendel J. Hann

    2015-01-01

    The Fire Regime Condition Class (FRCC) is a composite departure measure that compares current vegetation structure and fire regime to historical reference conditions. FRCC is computed as the average of: 1) Vegetation departure (VDEP) and 2) Regime (frequency and severity) departure (RDEP). In addition to the FRCC rating, the Vegetation Condition Class (VCC) and Regime...

  18. Electron acceleration in the bubble regime

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, Oliver

    2014-02-03

    The bubble regime of laser-wakefield acceleration has been studied over the recent years as an important alternative to classical accelerators. Several models and theories have been published, in particular a theory which provides scaling laws for acceleration parameters such as energy gain and acceleration length. This thesis deals with numerical simulations within the bubble regime, their comparison to these scaling laws and data obtained from experiments, as well as some specific phenomenona. With a comparison of the scaling laws with numerical results a parameter scan was able to show a large parameter space in which simulation and theory agree. An investigation of the limits of this parameter space revealed boundaries to other regimes, especially at very high (a{sub 0} > 100) and very low laser amplitudes (a{sub 0} < 4). Comparing simulation data with data from experiments concerning laser pulse development and electron energies, it was found that experimental results can be adequately reproduced using the Virtual-Laser-Plasma-Laboratory code. In collaboration with the Institut fuer Optik und Quantenelektronik at the Friedrich-Schiller University Jena synchrotron radiation emitted from the inside of the bubble was investigated. A simulation of the movement of the electrons inside the bubble together with time dependent histograms of the emitted radiation helped to prove that the majority of radiation created during a bubble acceleration originates from the inside of the bubble. This radiation can be used to diagnose the amplitude of oscillation of the trapped electrons. During a further study it was proven that the polarisation of synchrotron radiation from a bubble contains information about the exact oscillation direction. This oscillation was successfully controlled by using either a laser pulse with a tilted pulse front or an asymmetric laser pulse. First results of ongoing studies concerning injecting electrons into an existing bubble and a scheme called

  19. Numerical simulation of transitions between back discharge regimes

    International Nuclear Information System (INIS)

    Jansky, Jaroslav; Lemont, Florent; Bessieres, Delphine; Paillol, Jean

    2014-01-01

    This paper presents numerical simulations of transitions between back discharge regimes. Back discharge refers to any discharge initiated at or near a dielectric layer covering a passive electrode. In this work, a pinhole in a dielectric layer on a plane anode serves as a model for back discharge activity. We have studied transitions between back discharge regimes by varying the surface charge density on the dielectric layer and the electric field in front of the pinhole. From the variation of these two independent parameters, the back discharge regimes have been depicted as a mode diagram inspired by the experimental study of Masuda and Mizuno. The resulting diagram includes the different discharge regimes that are commonly observed in experiments. The propagation of a positive ionizing wave inside the pinhole toward its edge, and the resulting formation of a plasma zone at its exit constitute the onset stage of back discharge. From this stage, the transitions to volume discharge or surface discharge can occur. The volume discharge regime consists of the propagation of a discharge in space toward the cathode which can be superimposed with the propagation of a discharge above the dielectric layer surface. The diagram reveals the conditions for transitions between back discharge regimes. (authors)

  20. Do family policy regimes matter for children's well-being?

    Science.gov (United States)

    Engster, Daniel; Stensöta, Helena Olofsdotter

    2011-01-01

    Researchers have studied the impact of different welfare state regimes, and particularly family policy regimes, on gender equality. Very little research has been conducted, however, on the association between different family policy regimes and children's well-being. This article explores how the different family policy regimes of twenty OECD countries relate to children's well-being in the areas of child poverty, child mortality, and educational attainment and achievement. We focus specifically on three family policies: family cash and tax benefits, paid parenting leaves, and public child care support. Using panel data for the years 1995, 2000, and 2005, we test the association between these policies and child well-being while holding constant for a number of structural and policy variables. Our analysis shows that the dual-earner regimes, combining high levels of support for paid parenting leaves and public child care, are strongly associated with low levels of child poverty and child mortality. We find little long-term effect of family policies on educational achievement, but a significant positive correlation between high family policy support and higher educational attainment. We conclude that family policies have a significant impact on improving children's well-being, and that dual-earner regimes represent the best practice for promoting children's health and development.

  1. Triggered dynamics in a model of different fault creep regimes.

    Science.gov (United States)

    Kostić, Srđan; Franović, Igor; Perc, Matjaž; Vasović, Nebojša; Todorović, Kristina

    2014-06-23

    The study is focused on the effect of transient external force induced by a passing seismic wave on fault motion in different creep regimes. Displacement along the fault is represented by the movement of a spring-block model, whereby the uniform and oscillatory motion correspond to the fault dynamics in post-seismic and inter-seismic creep regime, respectively. The effect of the external force is introduced as a change of block acceleration in the form of a sine wave scaled by an exponential pulse. Model dynamics is examined for variable parameters of the induced acceleration changes in reference to periodic oscillations of the unperturbed system above the supercritical Hopf bifurcation curve. The analysis indicates the occurrence of weak irregular oscillations if external force acts in the post-seismic creep regime. When fault motion is exposed to external force in the inter-seismic creep regime, one finds the transition to quasiperiodic- or chaos-like motion, which we attribute to the precursory creep regime and seismic motion, respectively. If the triggered acceleration changes are of longer duration, a reverse transition from inter-seismic to post-seismic creep regime is detected on a larger time scale.

  2. Neoclassical transport in ERS regime

    International Nuclear Information System (INIS)

    Lin, Z.; Tang, W.; Lee, W.W.

    1996-01-01

    The core ion thermal conductivity has been observed to fall below the standard neoclassical level in recent TFTR reversed magnetic shear discharges. Due to the combination of high central q and small local inverse aspect ratio, the ion poloidal gyroradius can be larger than the minor radius and comparable to the pressure gradient scale length in this ERS regime. It is then expected that finite orbit width effects play a key role in modifying the standard picture of neoclassical transport. Specifically, both the trapped particle fraction and the banana orbit width axe reduced by the finite minor radius and possibly by the pressure-gradient-driven radial electric field. In addition, the steep pressure gradient can generate neoclassical poloidal flows which, in turn, could reduce the particle and heat transports. Results from analytic estimates as well as those from full toroidal gyrokinetic neoclassical simulations will be presented

  3. Unitary Housing Regimes in Transition

    DEFF Research Database (Denmark)

    Bengtsson, Bo; Jensen, Lotte

    2013-01-01

    Path dependence is strong in housing institutions and policy. In both Denmark and Sweden, today’s universal and ‘unitary’ (Kemeny) housing regimes can be traced back to institutions that were introduced fifty years back in history or more. Recently, universal and unitary housing systems...... in Scandinavia, and elsewhere, are under challenge from strong political and economic forces. These challenges can be summarized as economic cutbacks, privatization and Europeanization. Although both the Danish and the Swedish housing system are universal and unitary in character, they differ considerably...... in institutional detail. Both systems have corporatist features, however in Denmark public housing is based on local tenant democracy and control, and in Sweden on companies owned and controlled by the municipalities, combined with a centralized system of rent negotiations. In the paper the present challenges...

  4. Reassessing the nuclear liability regime

    International Nuclear Information System (INIS)

    Havinh Phuong

    1985-01-01

    The nuclear liability regime was thoroughly reviewed by nuclear plant operators, officials of regulatory authorities, and legal and insurance experts at the Symposium on Nuclear Third Party Liability and Insurance, held in September 1984 in Munich, Federal Republic of Germany. The symposium highlighted specific areas where adjustments or improvements would be needed in order to cope with practical problems encountered or emerging issues. By focusing on questions of legitimate concern to the public, it also sought to promote confidence in a compensation system for public protection that is in many ways unique. Topics addressed included the following: greater harmonization of the compensation amounts for nuclear damage established in different countries and in territorial scope; the concept of unlimited liability; the time limitation for compensation claims; the problem of proving causation; the concept of nuclear damage; and insurance coverage

  5. Hall effect in hopping regime

    International Nuclear Information System (INIS)

    Avdonin, A.; Skupiński, P.; Grasza, K.

    2016-01-01

    A simple description of the Hall effect in the hopping regime of conductivity in semiconductors is presented. Expressions for the Hall coefficient and Hall mobility are derived by considering averaged equilibrium electron transport in a single triangle of localization sites in a magnetic field. Dependence of the Hall coefficient is analyzed in a wide range of temperature and magnetic field values. Our theoretical result is applied to our experimental data on temperature dependence of Hall effect and Hall mobility in ZnO. - Highlights: • Expressions for Hall coefficient and mobility for hopping conductivity are derived. • Theoretical result is compared with experimental curves measured on ZnO. • Simultaneous action of free and hopping conduction channels is considered. • Non-linearity of hopping Hall coefficient is predicted.

  6. Hall effect in hopping regime

    Energy Technology Data Exchange (ETDEWEB)

    Avdonin, A., E-mail: avdonin@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Skupiński, P. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Grasza, K. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Institute of Electronic Materials Technology, ul. Wólczyńska 133, 01-919 Warszawa (Poland)

    2016-02-15

    A simple description of the Hall effect in the hopping regime of conductivity in semiconductors is presented. Expressions for the Hall coefficient and Hall mobility are derived by considering averaged equilibrium electron transport in a single triangle of localization sites in a magnetic field. Dependence of the Hall coefficient is analyzed in a wide range of temperature and magnetic field values. Our theoretical result is applied to our experimental data on temperature dependence of Hall effect and Hall mobility in ZnO. - Highlights: • Expressions for Hall coefficient and mobility for hopping conductivity are derived. • Theoretical result is compared with experimental curves measured on ZnO. • Simultaneous action of free and hopping conduction channels is considered. • Non-linearity of hopping Hall coefficient is predicted.

  7. Three novel tokamak plasma regimes in TFTR

    International Nuclear Information System (INIS)

    Furth, H.P.

    1985-10-01

    Aside from extending ''standard'' ohmic and neutral beam heating studies to advanced plasma parameters, TFTR has encountered a number of special plasma regimes that have the potential to shed new light on the physics of tokamak confinement and the optimal design of future D-T facilities: (1) High-powered, neutral beam heating at low plasma densities can maintain a highly reactive hot-ion population (with quasi-steady-state beam fueling and current drive) in a tokamak configuration of modest bulk-plasma confinement requirements. (2) Plasma displacement away from limiter contact lends itself to clarification of the role of edge-plasma recycling and radiation cooling within the overall pattern of tokamak heat flow. (3) Noncentral auxiliary heating (with a ''hollow'' power-deposition profile) should serve to raise the central tokamak plasma temperature without deterioration of central region confinement, thus facilitating the study of alpha-heating effects in TFTR. The experimental results of regime (3) support the theory that tokamak profile consistency is related to resistive kink stability and that the global energy confinement time is determined by transport properties of the plasma edge region

  8. Characterizing multistationarity regimes in biochemical reaction networks.

    Directory of Open Access Journals (Sweden)

    Irene Otero-Muras

    Full Text Available Switch like responses appear as common strategies in the regulation of cellular systems. Here we present a method to characterize bistable regimes in biochemical reaction networks that can be of use to both direct and reverse engineering of biological switches. In the design of a synthetic biological switch, it is important to study the capability for bistability of the underlying biochemical network structure. Chemical Reaction Network Theory (CRNT may help at this level to decide whether a given network has the capacity for multiple positive equilibria, based on their structural properties. However, in order to build a working switch, we also need to ensure that the bistability property is robust, by studying the conditions leading to the existence of two different steady states. In the reverse engineering of biological switches, knowledge collected about the bistable regimes of the underlying potential model structures can contribute at the model identification stage to a drastic reduction of the feasible region in the parameter space of search. In this work, we make use and extend previous results of the CRNT, aiming not only to discriminate whether a biochemical reaction network can exhibit multiple steady states, but also to determine the regions within the whole space of parameters capable of producing multistationarity. To that purpose we present and justify a condition on the parameters of biochemical networks for the appearance of multistationarity, and propose an efficient and reliable computational method to check its satisfaction through the parameter space.

  9. About the skin effect in transient regime; Sur l'effet de peau en regime transitoire

    Energy Technology Data Exchange (ETDEWEB)

    Podliasky, I.

    1957-06-15

    Whereas always more experimental devices are using a pulsed electric supply (the electromagnetic field is applied during few microseconds only), and whereas the studied phenomenon does not last more than few microseconds, this raises the question of the behaviour in transient regime of metallic circuits or of discharge in gases. In this technical note, the author addresses the case of sufficiently high and constant gas conductivity during the studied duration. Thus, he reports a theoretical study of the establishment of a current in a high-conductivity and large-radius cylinder, and more specifically the study of the behaviour of peripheral layers (in the neighbourhood of the metal-insulator separation)

  10. Accommodating human values in the climate regime

    Directory of Open Access Journals (Sweden)

    Rosalind Cook

    2008-12-01

    Full Text Available The climate regime addresses one of the most important challenges facing humankind today. However, while the environmental and economic sides of the problem are well represented, it lacks the inclusion of social and human aspects. The human rights regime, in contrast, is a regime which has been established precisely to implement human values. This article ex-plains the problems of climate change in terms of human values and argues that some proce-dures from the human rights regime offer possibilities for improvement. It is submitted that through the inclusion of human rights instruments, such as individual communication, pro-gressive realisation and authoritative interpretation, the inclusion of human values into the climate regime will be facilitated. This article presents these instruments and discusses their potential for inclusion in the climate regime.

  11. 3D study in modelling in static regime of a bi facial polycrystalline solar cell under intense light and under a constant magnetic field

    International Nuclear Information System (INIS)

    ZOUNGRANA Martial

    2010-01-01

    In this work we propose a three-dimensional (3D) study of magnetic field, light concentration and electron gradient concentration electric field respective influences on bi facial polycrystalline silicon solar cell behaviour. The hold account of these parameters in our study leads to the new expressions of continuity equations, electric and electronic parameters. On the basis of these equations, grain size, grain boundary recombination velocity, magnetic field and light intensity effects on carriers density, photocurrent, photovoltage, electric and electronic parameters are analysed. We finally propose an equivalent electric model of bi facial polycrystalline silicon solar cell under magnetic field. According to this model, electric parameters expressions was established (shunt and series resistances, space charge zone capacity ) and we study magnetic field, grain size, grain boundary recombination velocity and light concentration influences on these parameters.(Author) [fr

  12. De Facto Regimes in International Law

    OpenAIRE

    Essen, Jonte van

    2012-01-01

    The ambiguous position of de facto regimes in international law has long been the subject of scholarly debate and a source of political conflict. An assessment of the current standing of these regimes in international law and the consequences of actions by international actors on this status has, however, been long overdue. The manner in which de facto regimes are regarded internationally has serious consequences for the individuals under the influence of this legal grey area. Therefore, the ...

  13. Propagation of waves from an arbitrary shaped surface-A generalization of the Fresnel diffraction integral

    Science.gov (United States)

    Feshchenko, R. M.; Vinogradov, A. V.; Artyukov, I. A.

    2018-04-01

    Using the method of Laplace transform the field amplitude in the paraxial approximation is found in the two-dimensional free space using initial values of the amplitude specified on an arbitrary shaped monotonic curve. The obtained amplitude depends on one a priori unknown function, which can be found from a Volterra first kind integral equation. In a special case of field amplitude specified on a concave parabolic curve the exact solution is derived. Both solutions can be used to study the light propagation from arbitrary surfaces including grazing incidence X-ray mirrors. They can find applications in the analysis of coherent imaging problems of X-ray optics, in phase retrieval algorithms as well as in inverse problems in the cases when the initial field amplitude is sought on a curved surface.

  14. Proliferation Control Regimes: Background and Status

    National Research Council Canada - National Science Library

    Nikitin, Mary B; Kerr, Paul; Bowman, Steve; Hildreth, Steven A

    2008-01-01

    .... national security interests. Multilateral regimes were established to restrict trade in nuclear, chemical, and biological weapons and missile technologies, and to monitor their civil applications...

  15. Proliferation Control Regimes: Background and Status

    National Research Council Canada - National Science Library

    Squassoni, Sharon; Bowman, Steve; Hildreth, Steven A

    2006-01-01

    .... national security interests. Multilateral regimes were established to restrict trade in nuclear, chemical, and biological weapons and missile technologies, and to monitor their civil applications...

  16. Optimal integration of linear Fresnel reflector with gas turbine cogeneration power plant

    International Nuclear Information System (INIS)

    Dabwan, Yousef N.; Mokheimer, Esmail M.A.

    2017-01-01

    generating capacities of the gas turbine and different areas of solar collectors have been examined. Thermoflow software simulation results have been used to identify the optimal configuration and sizing of the gas turbine and the solar field of the integrated solar gas turbine cogeneration plant (ISGCPP) required to achieve the required steam generation with the minimum cost and environmental impact. The study revealed that ISGCPP can reduce the levelized electricity cost by 76–85% relative to the fully-solar-powered LFR power plant. Moreover, the study identified the configuration of ISGCPP with a gas turbine size of 50 MWe capacity and 93 ha of LFR solar field as the optimally integrated plant. It reduces the annual CO 2 emission by 100 k Tonne (18%) in comparison with that emitted by the corresponding conventional plant with 50 MWe and 400 k tonne (43.75%) compared with that emitted by the original conventional plant with a gas turbine if 150 MWe power generation capacity. The study revealed also that integrating the LFR technology with a gas turbine cogeneration power plant in locations with high solar insolation was proved to have more economic feasibility than CO 2 capturing technology. Under Dhahran weather conditions, the LEC of about 5 USȻ/kW h is obtained using the proposed optimally configured ISGCPP compared with about 7.5 USȻ/kW h obtained by the corresponding conventional cycle integrated with carbon capture technology. In other words, the ISGCPP reduces the LEC by 50% while achieving the same reduction of CO 2 emission by an equivalent conventional plant integrated with carbon capture technology.

  17. Comparative study on the influence of depth, number and arrangement of dimples on the flow and heat transfer characteristics at turbulent flow regimes

    Science.gov (United States)

    Nazari, Saeed; Zamani, Mahdi; Moshizi, Sajad A.

    2018-03-01

    The ensuing study is dedicated to a series of numerical investigations concerning the effects of various geometric parameters of dimpled plates on the flow structure and heat transfer performance in a rectangular duct compared to the smooth plate. These parameters are the arrangement, number and depth of dimples. Two widely used staggered and square patterns in addition to a triangular arrangement, and three dimple depths (Δ = δ/d = 0.25, 0.375 and 0.5) have been chosen for this particular study. All studies have been conducted at three different Reynolds numbers Re = 25,000, 50,000 and 100,000. In order to capture the flow structures in the vicinity of dimples and contributing phenomena related to the boundary layer interactions, fully structured grids with y+ < 1 have been generated for all the cases. The realizable k t -ɛ two-layer model was selected as a proper turbulent model. It can be observed from the obtained results that higher effective area for heat transfer and a myriad of turbulent vortices mixing the hot fluid near the surface with the passing cold fluid generated from the downwind rims of dimples are the causes for improved average Nusselt number in the dimpled surface in comparison to the smooth plate. However, more pressure loss due to the higher friction drag and recirculation zones inside dimples will exist as a drawback in this system. Moreover, for all arrangements increasing dimple ratio Δ has a negative impact on the heat transfer augmentation and also deteriorates the pressure loss, which leads to this fact that Δ = 0.25 serves as the best option for the dimple depth.

  18. Estudos da eletrodeposição de metais em regime de subtensão Studies of the underpotential deposition of metals

    Directory of Open Access Journals (Sweden)

    Mauro C. Santos

    2000-06-01

    Full Text Available This work reviews recent studies of underpotential deposition (UPD of several metals on Pt and Au substrates performed in the Grupo de Materiais Eletroquímicos e Métodos Eletroanalíticos (IQSC -- USP, São Carlos. The UPD Cu, Cd and Pb on Pt were analysed in terms of their influence in the oxygen evolution reaction. Partial blockage of surface active sites, promoted by Pb ad-atoms, resulted in a change from water to hydrogen peroxide as the final product. The Ag UPD on Pt and Au substrates was also discussed in this work. A detailed model of charge calculation for Ag monolayer was developed and confirmed by the rotating ring-disk data. The partial charge transfer in UPD studies was analysed in the Cd/Pt and Cd/Au systems and a value of 0.5 was found for the adsorption electrovalence of Cd ad-ions. The Sn/Pt UPD systems were studied from the point of view of the valences of metallic ions in solution. The deposition from Sn(IV generates a full monolayer with a maximum occupation of approximately 40% of the surface active sites (340 µC cm-2 plus 105 µC cm-2 of Hads (half monolayer. Changing the metallic ion for Sn(II, it was possible to deposit a full monolayer (210 µC cm-2 without any detectable Hads. Finally, the effect of anions was discussed in the Zn/Pt and Zn/Au systems. Here, the hydrogen evolution reaction (her and the hydrogen adsorption/desorption were used in order to investigate the maximum coverage of the surface with Zn ad-atoms. The full monolayer, characterised by the complete absence of Hads, was achieved only in 0.5 M HF solutions.

  19. The Investigation of New Magnetic Materials and Their Phenomena Using Ultrafast Fresnel Transmission Electron Microscopy

    Science.gov (United States)

    Schliep, Karl B.

    the University of Minnesota and how I explored the application of it toward the investigation of magnetic materials. In my discussion of UEM, I have made a concerted effort to highlight the unique challenges faced when getting a UEM lab running so that new researchers may circumvent these challenges. Of note in my graduate studies, I assisted in the development of three different magnetic material systems, strained Fe nanoparticles for permanent magnetic applications, FePd for applications in spintronic devices, and a rare-earth transition-metal (RE-TM) alloy that exhibits new magneto-optic phenomena. In studying the morphological and magnetic effects of lasers on these RE-TM alloys using the in situ laser irradiation capabilities of UEM along with standard TEM techniques and computational modeling, I uncovered a possible limitation in their utility for memory applications. Furthermore, with the aid of particle tracing software, I was able to optimize our UEM system for magnetic imaging and demonstrate the resolution of ultrafast demagnetization using UEM.

  20. Institutional design and regime effectiveness in transboundary river management – the Elbe water quality regime

    Directory of Open Access Journals (Sweden)

    I. Dombrowsky

    2008-02-01

    Full Text Available The literature on transboundary river management suggests that institutions play an important role in bringing about cooperation. However, knowledge about how such institutions should be designed in order to do so remains limited. One way to learn more about adequate institutional design is to assess the effectiveness of existing regimes, and to trace the causal relationships that lead to the respective outcomes. In order to gain further insights into the relationship between institutional design and regime effectiveness, this paper presents a study on the water quality regime of the International Commission for the Protection of the Elbe (ICPE. The analysis is based on a review of pertinent documents and ten qualitative interviews with Czech and German Commission members and NGO representatives. Particular emphasis has been put on determining the ICPE's specific contribution and the no-regime counterfactual as well as on the perceived expediency of the institutional arrangements. The study shows overall that the countries were relatively successful in improving water quality in the Elbe basin. However, this outcome can only partly be attributed to the ICPE itself. Furthermore, the ICPE's contribution towards achieving the various goals varied significantly between the different areas of activity: it was relatively significant where the main responsibility for action lay with the public authorities, such as in the area of wastewater treatment and the establishment of an international alarm plan and model, but was practically non-existent in the reduction of non-point pollution from agriculture, where success depended on the behavior of individual private actors (farmers. The commission contributed towards problem solving by serving as a forum for the joint identification of priorities for action from a basin-wide perspective. The resulting international obligations increased the power of national water administrations and their access to funds

  1. Nonlinear approaches for phase retrieval in the Fresnel region for hard X-ray imaging

    International Nuclear Information System (INIS)

    Davidoiu, Valentina

    2013-01-01

    The development of highly coherent X-ray sources offers new possibilities to image biological structures at different scales exploiting the refraction of X-rays. The coherence properties of the third-generation synchrotron radiation sources enables efficient implementations of phase contrast techniques. One of the first measurements of the intensity variations due to phase contrast has been reported in 1995 at the European Synchrotron Radiation Facility (ESRF). Phase imaging coupled to tomography acquisition allows three dimensional imaging with an increased sensitivity compared to absorption CT. This technique is particularly attractive to image samples with low absorption constituents. Phase contrast has many applications, ranging from material science, paleontology, bone research to medicine and biology. Several methods to achieve X-ray phase contrast have been proposed during the last years. In propagation based phase contrast, the measurements are made at different sample-to-detector distances. While the intensity data can be acquired and recorded, the phase information of the signal has to be 'retrieved' from the modulus data only. Phase retrieval is thus an ill-posed nonlinear problem and regularization techniques including a priori knowledge are necessary to obtain stable solutions. Several phase recovery methods have been developed in recent years. These approaches generally formulate the phase retrieval problem as a linear one. Nonlinear treatments have not been much investigated. The main purpose of this work was to propose and evaluate new algorithms, in particularly taking into account the nonlinearity of the direct problem. In the first part of this work, we present a Landweber type nonlinear iterative scheme to solve the propagation based phase retrieval problem. This approach uses the analytic expression of the Frechet derivative of the phase-intensity relationship and of its adjoint, which are presented in detail. We also study the effect of

  2. The Relationship Between the Foreign Exchange Regime and Macroeconomic Performance in Eastern Africa

    OpenAIRE

    Janet Gale Stotsky; Manuk Ghazanchyan; Olumuyiwa S Adedeji; Nils Øvind Maehle

    2012-01-01

    This study examines the relationship between the foreign exchange regime and macroeconomic performance in Eastern Africa. The study focuses on seven countries, five of which decisively liberalized their foreign exchange regimes. The study assesses the relationship between (i) growth and various determinants, including the exchange regime, the real exchange rate, and current account liberalization; and (ii) inflation and various determinants, including lagged inflation, the nominal exchange ra...

  3. A climatology of low level wind regimes over Central America using a weather type classification approach.

    Directory of Open Access Journals (Sweden)

    Fernán eSáenz

    2015-04-01

    Full Text Available Based on the potential of the weather types classification method to study synoptic features, this study proposes the application of such methodology for the identification of the main large scale patterns related with weather in Central America. Using ERA Interim low-level winds in a domain that encompasses the intra-Americas sea, the eastern tropical Pacific, southern North America, Central America and northern South America; the K-means clustering algorithm was applied to find recurrent regimes of low-level winds. Eleven regimes were identified and good coherency between the results and known features of regional circulation was found. It was determined that the main large scale patterns can be either locally forced or a response to tropical-extratropical interactions. Moreover, the local forcing dominates the summer regimes whereas mid latitude interactions lead winter regimes. The study of the relationship between the large scale patterns and regional precipitation shows that winter regimes are related with the Caribbean-Pacific precipitation seesaw. Summer regimes, on the other hand, enhance the Caribbean-Pacific precipitation contrasting distribution as a function of the dominant regimes. A strong influence of ENSO on the frequency and duration of the regimes was found. It was determined that the specific effect of ENSO on the regimes depends on whether the circulation is locally forced or lead by the interaction between the tropics and the mid-latitudes. The study of the cold surges using the information of the identified regimes revealed that three regimes are linkable with the occurrence of cold surges that affect Central America and its precipitation. As the winter regimes are largely dependent of mid-latitude interaction with the tropics, the effect that ENSO has on the Jet Stream is reflected in the winter regimes. An automated analysis of large scale conditions based on reanalysis and/or model data seems useful for both dynamical

  4. Laboratory and modeling studies on the effects of water and soot emissions and ambient conditions on the properties of contrail ice particles in the jet regime

    Directory of Open Access Journals (Sweden)

    H.-W. Wong

    2013-10-01

    Full Text Available Contrails and contrail-induced cirrus clouds are identified as the most uncertain components in determining aviation impacts on global climate change. Parameters affecting contrail ice particle formation immediately after the engine exit plane (< 5 s in plume age may be critical to ice particle properties used in large-scale models predicting contrail radiative forcing. Despite this, detailed understanding of these parametric effects is still limited. In this paper, we present results from recent laboratory and modeling studies conducted to investigate the effects of water and soot emissions and ambient conditions on near-field formation of contrail ice particles and ice particle properties. The Particle Aerosol Laboratory (PAL at the NASA Glenn Research Center and the Aerodyne microphysical parcel model for contrail ice particle formation were employed. Our studies show that exhaust water concentration has a significant impact on contrail ice particle formation and properties. When soot particles were introduced, ice particle formation was observed only when exhaust water concentration was above a critical level. When no soot or sulfuric acid was introduced, no ice particle formation was observed, suggesting that ice particle formation from homogeneous nucleation followed by homogeneous freezing of liquid water was unfavorable. Soot particles were found to compete for water vapor condensation, and higher soot concentrations emitted into the chamber resulted in smaller ice particles being formed. Chamber conditions corresponding to higher cruising altitudes were found to favor ice particle formation. The microphysical model captures trends of particle extinction measurements well, but discrepancies between the model and the optical particle counter measurements exist as the model predicts narrower ice particle size distributions and ice particle sizes nearly a factor of two larger than measured. These discrepancies are likely due to particle

  5. Advancing Littoral Zone Aerosol Prediction via Holistic Studies in Regime-Dependent Flows: August 3-9, 2016 Middle East Dust Event

    Science.gov (United States)

    Solbrig, J. E.; Miller, S. D.; van den Heever, S. C.; Kreidenweis, S. M.; Oo, M. M.; Zupanski, M.; Zhang, J.; Wang, J.; Holz, R.; Albers, S. C.; Grasso, L. D.; Kliewer, A.; Bukowski, J.; Park, J.; Saleeby, S. M.; Wu, T. C.

    2017-12-01

    Coastal regions represent a complex environment for meteorological processes, their effect on aerosol distributions, and the resulting impacts of those aerosols. These regions are rife with discontinuities that make dynamical processes difficult to predict and confound optical retrieval algorithms with highly variable and poorly characterized backgrounds. Local dynamics can be complicated by interactions between maritime and continental airmasses and the presence of coastal terrain. Additionally, coastal shallow water and high-turbidity produce backgrounds with high water leaving radiance which biases results from remote sensing retrievals. Here we present the highlights of the first two years of work from a Multi-disciplinary University Research Initiative entitled Holistic Analysis of Aerosol in Littoral Environments (HAALE-MURI) with specific focus on a dust event that occurred during the period of August 3-9 2016. During this period, two large dust plumes were observed advecting across the Arabian Peninsula. The first, embedded in a dry airmass, moved across the peninsula from north-west to south-east. This plume eventually stalls as it encounters a moist airmass, likely driven by the sea breeze. Embedded in the moist airmass is a second dust plume lofted from Oman, which then advects northwards over the Persian Gulf. This case presents significant challenges for forecasting, remote sensing, and data assimilation due to a complex meteorological environment and variable coastal bright-water backgrounds. The project team, who endeavor to advance our fundamental understanding of the factors that govern aerosol distribution, optical properties, and microphysical properties in the coastal regions, have focused on this case as our first in-depth case study. We demonstrate new retrieval techniques during both day and night including retrievals over bright coastal waters, a novel approach to in-line data assimilation of aerosol properties including AOT, and the results

  6. Modeling Whistler Wave Generation Regimes In Magnetospheric Cyclotron Maser

    Science.gov (United States)

    Pasmanik, D. L.; Demekhov, A. G.; Trakhtengerts, V. Y.; Parrot, M.

    Numerical analysis of the model for cyclotron instability development in the Earth magnetosphere is made.This model, based on the self-consistent set of equations of quasi-linear plasma theory, describes different regimes of wave generation and related energetic particle precipitation. As the source of free energy the injection of energetic electrons with transverse anisotropic distribution function to the interaction region is considered. Two different mechanisms of energetic electron loss from the interaction region are discussed. The first one is precipitation of energetic particles via the loss cone. The other mechanism is drift of particles away from the interaction region across the mag- netic field line. In the case of interaction in plasmasphere or rather large areas of cold plasma density enhancement the loss cone precipitation are dominant. For interaction in a subauroral duct losses due to drift are most effective. A parametric study of the model for both mechanisms of particle losses is made. The main attention is paid to the analysis of generation regimes for different characteristics of energetic electron source, such as the shape of pitch-angle distributions and elec- tron density. We show that in addition to the well-known stationary generation and periodic regime with successive spikes of similar shape, more complex forms of wave spectrum exist. In particular, we found a periodic regime, in which a single period in- cludes two separate spikes with different spectral shapes. In another regime, periodic generation of spikes at higher frequencies together with quasi-stationary generation at lower frequencies occurs. Quasi-periodic regime with spike overlapping, i.e. when generation of a new spike begins before the previous one is over is also found. Results obtained are compared with experimental data on quasi-periodic regimes of whistler wave generation.

  7. Weather regimes in past climate atmospheric general circulation model simulations

    Energy Technology Data Exchange (ETDEWEB)

    Kageyama, M.; Ramstein, G. [CEA Saclay, Gif-sur-Yvette (France). Lab. des Sci. du Climat et de l' Environnement; D' Andrea, F.; Vautard, R. [Laboratoire de Meteorologie Dynamique, Ecole Normale Superieure, Paris (France); Valdes, P.J. [Department of Meteorology, University of Reading (United Kingdom)

    1999-10-01

    We investigate the climates of the present-day, inception of the last glaciation (115000 y ago) and last glacial maximum (21000 y ago) in the extratropical north Atlantic and Europe, as simulated by the laboratoire de Meteorologie dynamique atmospheric general circulation model. We use these simulations to investigate the low-frequency variability of the model in different climates. The aim is to evaluate whether changes in the intraseasonal variability, which we characterize using weather regimes, can help describe the impact of different boundary conditions on climate and give a better understanding of climate change processes. Weather regimes are defined as the most recurrent patterns in the 500 hPa geopotential height, using a clustering algorithm method. The regimes found in the climate simulations of the present-day and inception of the last glaciation are similar in their number and their structure. It is the regimes' populations which are found to be different for these climates, with an increase of the model's blocked regime and a decrease in the zonal regime at the inception of the last glaciation. This description reinforces the conclusions from a study of the differences between the climatological averages of the different runs and confirms the northeastward shift to the tail of the Atlantic storm-track, which would favour more precipitation over the site of growth of the Fennoscandian ice-sheet. On the other hand, the last glacial maximum results over this sector are not found to be classifiable, showing that the change in boundary conditions can be responsible for severe changes in the weather regime and low-frequency dynamics. The LGM Atlantic low-frequency variability appears to be dominated by a large-scale retrogressing wave with a period 40 to 50 days. (orig.)

  8. Full-scale model development of the WWER-440 reactor fuel rod bundle for core temperature regime study under reflooding conditions

    International Nuclear Information System (INIS)

    Bezrukov, Yu.A.; Logvinov, S.A.; Levchuk, S.V.; Nakladnov, V.D.; Onshin, V.P.; Sokolov, A.S.

    1982-01-01

    Consideration is given to the issues of a full scale WWER-440 fuel rod bundle imitation. An imitator contains a molybdenum heating rod inclosed in stainless steel shell. The shell diameter is 9 mm, the heated length is 2500 mm, the total len.o.th is 2855 mm. 125 fuel rod imitators are set in the bundle mock-up. The experiments were run on a test facility imitating the WWER-440 reactor primary loop, providing the conditions of the loop breaking. The mock-up thermal hydraulics has been studied during the refloodino. stage. The mock-up was heated up to predetermined initial temperature at a low power level with saturated steam cooling. Then the steam input was stopped, the power level rarapidly rised up to a given value and the cooling water injected. Simultaneously with water injection all the measured parameters monitoring was started. Both at the top spraying and combined cooling temperature oscillations in the upper and middle parts of the mock-up were observed. At the bottom reflooding the mock-up cooling down took more time, thereat temperature inthe upper part first slowly rised during reflooding then decreased and then dropped abruptly at thefront coming up [ru

  9. Numerical solution of the Maxwell-Vlasov equations in the periodic regime. Application to the study of isotope separation by ion cyclotron resonance

    International Nuclear Information System (INIS)

    Omnes, P.

    1999-01-01

    This work is dedicated to the study of the behaviour of a magnetic confined plasma that is excited by a purely sinusoidal electric current delivered by an antenna. The response of the electrons to the electromagnetic field is considered as linear, whereas the ions of the plasma are represented by a non-relativistic Vlasov equation. In order to avoid transients, the coupled Maxwell-Vlasov equations are solved in a periodic mode and in a bounded domain. An equivalent electric conductivity tensor has been defined, this tensor is a linear operator that links the electric current generated by the movement of the particles to the electromagnetic field. Theoretical considerations can assure the existence and uniqueness of a periodical solution to Vlasov equations and of a solution to Maxwell equations in harmonic mode. The system of equations is periodical and has been solved by using an iterative method. The application of this method to the simulation of a isotopic separation device based on ionic cyclotron resonance has shown that the convergence is reached in a few iterations and that the solution is valid. Furthermore a method based on a finite-volume formulation of Maxwell equations in the time domain is presented. 2 new variables are defined in order to better take into account the Gauss' law and the conservation of the magnetic flux, the new system is still hyperbolic. The parallelization of the process has been successfully realized. (A.C.)

  10. Unidade de estudos de mastites em pequenos ruminantes: estudos em ovinos de regime extensivo Small ruminant mastitis unity: studies on grazing ewes

    Directory of Open Access Journals (Sweden)

    M.C. Queiroga

    2007-01-01

    reduce mastitis prevalence in small ruminants and thus to improve milk production and quality, with benefits for both milk and cheese producers as well as protecting food consumers. Work already developed by this team comprises isolation and identification of ovine mastitis pathogens, detection of virulence factors in the most relevant bacteria, studies on the infection mechanisms and host local and systemic immune response and other epidemiological studies. A deeper knowledge of aetiology and physiopathology of ovine mastitis, aiming at understanding the immune response modulation, may contribute to the development of control methods based on immune stimulation, alternative to antibiotic treatment.

  11. Numerical Study for Turbulent Heat Transfer in Helical Wired Sub-channel Flow Regime of Duct-less Assembly in SFR

    International Nuclear Information System (INIS)

    You, Byunghyun; Jeong, Yong Hoon

    2014-01-01

    A fuel assembly had hexagonal structure adjacent to 6 fuel assemblies, which influence to the target fuel assembly due to elimination of duct. For calculating the influence, 6 additional channels were generated between the adjacent fuel assemblies and cross flow model was applied to the channels. The adjacent fuel assemblies were analyzed and the results were used in the additional channel as boundary condition of the target fuel assembly. To design the specifications of duct-less assembly, modified or brand-new thermal-hydraulic methodology is needed which is using MATRA-LMR and CFD codes in this study. The MATRA-LMR is a sub-channel analysis code for LMR that has been developed in Korea Atomic Energy Research Institute. It is designed to analyze a fuel assembly with wire-wrap and duct structure. However, the duct-less core is not able to be analyzed by the MATRA-LMR which doesn't consider cross flow between the fuel assemblies and effect of grid spacer. The code need improvement by editing source code to eliminate effect of duct and analyze pressure drop and mixing between the sub-channels caused by grid spacer and cross flow between the fuel assemblies. To validate reformed pressure drop model and cross flow model in MATRA-LMR, CFD analysis is performed. For verifying the results of CFD, LMR subchannel experimental data is benchmarked which is done by ORNL. The verified CFD for thermalhydraulic analysis calculated pressure drop and mixing caused by grid spacer and cross flow between fuel assemblies

  12. Part I: Synthesis and study of nonacene derivatives; Part II: Optoelectronic properties of metal-semiconductor nanocomposites in strongly coupled regime

    Science.gov (United States)

    Khon, Dmitriy

    Acenes are polycyclic aromatic hydrocarbons (PAHs) consisting of linearly fused benzene rings. In the recent past, acenes have been of interest from fundamental and applied perspectives. Smaller acenes such as benzene, naphthalene, and anthracene are among the most studied organic compounds and their properties are well explored. Pentacene has received considerable attention as the most promising active semiconductor for use in organic thin film transistors (TFT) because of its high charge-carrier mobility; however, poor environmental stability is one of the problems limiting its practical application. As the number of rings increases, the members of the acene family become increasingly reactive. The successful synthesis of heptacene developed by Mondal et al. used the Strating-Zwanenberg photodecarbonylation reaction. The lesser stability of the tetracene moieties in the nonacene photoprecursor compared to the anthracene moieties of the heptacene process make its synthesis more challenging. The latter scheme requires 2,3-dibromoanthracene as one of the starting materials. Besides the poor solubility of 2,3-dibromoanthracene, failure was also due to insufficient formation of anthracyne upon treatment of 2,3-dibromoanthracene with n-BuLi. Although the initial idea didn't work we used the same scheme replacing 2,3-dibromoanthracene with 7,8-dibromo-1,4-dihydroanthracene. The reaction of the latter with 5,6,7,8-tetramethylenebicyclo[2.2.2]oct-2-ene gave 1,4,7,8,9,12,15,18,19,20-octadecahydro-8,19-diethenononacene albeit in low yield. Multiple attempts to dehydrogenate the non-aromatic rings using DDQ and other reagents under various conditions failed to produce the desired compound. Recently Miller reported the synthesis of relatively stable heptacene derivatives having a combination of arylthio and o-dialkylphenyl substituents. Miller's scheme used 1,2,4,5-tetrakis(bromomethyl)-3,6-bis(4'- t-butylthiophenyl)benzene as the core precursor. Another synthetic approach

  13. Criteria and procedures for stability studies - adopted measures for improving system dynamic performance; Criterios e procedimentos para estudos de estabilidade - definicao de acoes para a melhoria do desempenho em regime transitorio e dinamico de sistemas de transmissao

    Energy Technology Data Exchange (ETDEWEB)

    Figueiredo, Erli F [FURNAS, Rio de Janeiro, RJ (Brazil); Fontoura, Roberto N [ELETROBRAS, Rio de Janeiro, RJ (Brazil); Souza, Luiz Gastao C [ELETROSUL, Curitiba, PR (Brazil); Barros, Joao Ricardo P. de [Companhia Hidroeletrica do Sao Francisco (CHESF), Recife, PE (Brazil); Aires, Joao C. de O. [Light Servicos de Eletricidade S.A., Rio de Janeiro, RJ (Brazil); Etrusco, Wellignton [Companhia Energetica de Sao Paulo (CESP), SP (Brazil); Rosa, Aciron B. de [Companhia Estadual de Energia Eletrica do Estado do Rio Grande do Sul (CEEE), Porto Alegre, RS (Brazil); Daldagan, Maria L [Companhia Paranaense de Energia (COPEL), Curitiba, PR (Brazil); Bastos, Jose R [Eletricidade de Sao Paulo, Sao Paulo, SP (Brazil); Yamamura, Paulo [ELETRONORTE, Belem, PA (Brazil); Luz, Ariosto [Companhia de Energia Eltrica da Bahia, Salvador, BA (Brazil); Oliveira, Elizabeth F [CELG (Brazil); Mello, Albert C.G. de [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil); Souza, Itamar [Centrais Eletricas de Santa Catarina S.A. (CELESC), Florianopolis, SC (Brazil); Oliveira, Amaury R.C. [Companhia Energetica de Minas Gerais (CEMIG), Belo Horizonte, MG (Brazil); Martins, Junior, Jose A [Companhia Paulista de Forca e Luz (CPFL), Campinas, SP (Brazil); Ferreira, Jose S [Espirito Santo Centrias Eletricas S.A. (ESCELSA), Vitotia, ES (Brazil); Molina, Jair M [Empresa Energetica do Mato Grosso do Sul S.A. (ENERSUL), Campo Grande, MS (Brazil); Pereira, Marcel J.A. [Centrais Eltricas do Para S.A. (CELPA); [Belem, PA (Brazil); Rocha Neto, Cassiano, C. [Companhia Energetica do Ceara (COELCE), Fortaleza, CE (Brazil); Coelho, Simone N [CELPE (Brazil); Silva, Robson P [CEAL (Brazil)

    1994-12-31

    This work presents criterion and proceedings to the analysis of the performance of AC and DC transmission systems point to point and multi-terminal, in dynamic and transient regime. (author) 9 refs., 2 figs., 2 tabs.

  14. Fresnel's Lighthouse Lenses

    Science.gov (United States)

    Greenslade, Thomas B., Jr.

    2007-01-01

    One of the rewards of walking up the scores of steps winding around the inside of the shaft of a lighthouse is turning inward and examining the glass optical system. This arrangement of prisms, lenses, and reflectors is used to project the light from a relatively small source in a beam that can be seen far at sea.

  15. Deployable wireless Fresnel lens

    Science.gov (United States)

    Kennedy, Timothy F. (Inventor); Fink, Patrick W. (Inventor); Chu, Andrew W. (Inventor); Lin, Gregory Y. (Inventor)

    2013-01-01

    Apparatus and methods for enhancing the gain of a wireless signal are provided. In at least one specific embodiment, the apparatus can include a screen comprised of one or more electrically conductive regions for reflecting electromagnetic radiation and one or more non-conductive regions for permitting electromagnetic radiation therethrough. The one or more electrically conductive regions can be disposed adjacent to at least one of the one or more non-conductive regions. The apparatus can also include a support member disposed about at least a portion of the screen. The screen can be capable of collapsing by twisting the support member in opposite screw senses to form interleaved concentric sections.

  16. Effects of time-variable exposure regimes of the insecticide chlorpyrifos on freshwater invertebrate communities in microcosms

    NARCIS (Netherlands)

    Zafar, M.I.; Wijngaarden, van R.; Roessink, I.; Brink, van den P.J.

    2011-01-01

    The present study compared the effects of different time-variable exposure regimes having the same time-weighted average (TWA) concentration of the organophosphate insecticide chlorpyrifos on freshwater invertebrate communities to enable extrapolation of effects across exposure regimes. The

  17. Second regime tokamak operation at large aspect ratio

    International Nuclear Information System (INIS)

    Navratil, G.A.

    1989-01-01

    This paper reviews the need for high beta in economic tokamak reactors and summarizes recent results on the scaling of the second regime beta limit for high-n ballooning modes using optimized pressure profiles as well as results on low-n mode stability at the first regime beta limit from the Columbia HBT tokamak. While several experiments have studied ballooning limits using high εβ p plasmas, the most important question for the use of the second stability regime for tokamak reactor improvement is how to achieve these high values of εβ p while at the same time increasing the value of beta to several times the Troyon beta limit. An approach to the study of this key question on beta limits using modest sized, large aspect ratio tokamaks is described. (author). 28 refs, 7 figs, 1 tab

  18. Capacitance densitometer for flow regime identification

    International Nuclear Information System (INIS)

    Shipp, R.L. Jr.

    1978-01-01

    This invention relates to a capacitance densitometer for determining the flow regime of a two-phase flow system. A two-element capacitance densitometer is used in conjunction with a conventional single-beam gamma densitometer to unambiguously identify the prevailing flow regime and the average density of a flowing fluid

  19. TARIFFS AND REGIMES OF POWER CONSUMPTION

    Directory of Open Access Journals (Sweden)

    S. V. Batsova

    2010-01-01

    Full Text Available Analysis of regimes of electro-consumption at RUP «BMZ» is carried out. It is shown that in conditions of rapid growth of prices for electric power one of the conditions of reduction of production expenses is to be the increase of efficiency of the electro-consumption regimes control.

  20. Strengthening the nuclear non-proliferation regime

    International Nuclear Information System (INIS)

    Carlson, J.

    2003-01-01

    Although the nuclear non-proliferation regime has enjoyed considerable success, today the regime has never been under greater threat. Three states have challenged the objectives of the NPT, and there is a technology challenge - the spread of centrifuge enrichment technology and know-how. A major issue confronting the international community is, how to deal with a determined proliferator? Despite this gloomy scenario, however, the non-proliferation regime has considerable strengths - many of which can be developed further. The regime comprises complex interacting and mutually reinforcing elements. At its centre is the NPT - with IAEA safeguards as the Treaty's verification mechanism. Important complementary elements include: restraint in the supply and the acquisition of sensitive technologies; multilateral regimes such as the CTBT and proposed FMCT; various regional and bilateral regimes; the range of security and arms control arrangements outside the nuclear area (including other WMD regimes); and the development of proliferation-resistant technologies. Especially important are political incentives and sanctions in support of non-proliferation objectives. This paper outlines some of the key issues facing the non-proliferation regime