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Sample records for fresnel regime studied

  1. Optimization of coherent lidar performance with graded-reflectance transmitter resonator optics in the low equivalent Fresnel number regime.

    Science.gov (United States)

    Tratt, D M; Bowers, M S

    1996-08-20

    Using a diffractive eigenmode treatment to model the laser output we show that graded-reflectance resonator optics offer significant efficiency benefits over conventional hard-edge coupled unstable resonators in the context of coherent detection lidar applications. Extending previous research pertinent to the high equivalent Fresnel number regime, we have modeled the optimum performance of a notional super-Gaussian coupled cavity as a function of the key resonator parameters in the low equivalent Fresnel number (lidar transmitters operated within this regime.

  2. 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.

  3. An Experimental Study on the Effect of Using Fresnel Lenses on the Performance of Solar Stills

    Science.gov (United States)

    Abdelsalam, Tarek I.; Abdel-Mesih, Bahy

    The global water concern is mainly about the scarcity of fresh water resources despite the abundance of saline and brackish water in oceans, seas, and underground. Solar desalination offers a worthy solution to produce fresh water by using solar radiation, which also lessens the energy concern by offering a renewable source of energy to alter the consumption of fossil fuels and other non-renewable resources. One of the solar desalination technologies is the solar still system, which is a portable unit capable of producing distilled water by evaporating brackish or saline water by using solar thermal energy. The steam is then condensed on the inside of the glass cover and collected as fresh water. Solar stills are easy to manufacture and install using local materials and workmanship, which suits underprivileged remote communities that face difficulties in finding clean potable water, while locating near a source of saline water. However, efficiency and productivity of solar stills are still feeble when compared to other traditional desalination techniques. As an attempt to overcome these issues, an upgraded system is proposed and tested experimentally to augment the incoming solar radiation falling on the top glass surface of the still by concentrating extra solar radiation to preheat the flowing feedwater to the solar still system. The results of the experimental study showed that the integration of linear Fresnel lenses has approximately tripled the productivity of distilled water and improved efficiency of a solar still, by about 68.76 %, when compared to a conventional non-concentrating solar still.

  4. 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.

  5. Mathematical Simulation for Integrated Linear Fresnel Spectrometer Chip

    Science.gov (United States)

    Park, Yeonjoon; Yoon, Hargoon; Lee, Uhn; King, Glen C.; Choi, Sang H.

    2012-01-01

    A miniaturized solid-state optical spectrometer chip was designed with a linear gradient-gap Fresnel grating which was mounted perpendicularly to a sensor array surface and simulated for its performance and functionality. Unlike common spectrometers which are based on Fraunhoffer diffraction with a regular periodic line grating, the new linear gradient grating Fresnel spectrometer chip can be miniaturized to a much smaller form-factor into the Fresnel regime exceeding the limit of conventional spectrometers. This mathematical calculation shows that building a tiny motionless multi-pixel microspectrometer chip which is smaller than 1 cubic millimter of optical path volume is possible. The new Fresnel spectrometer chip is proportional to the energy scale (hc/lambda), while the conventional spectrometers are proportional to the wavelength scale (lambda). We report the theoretical optical working principle and new data collection algorithm of the new Fresnel spectrometer to build a compact integrated optical chip.

  6. 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.

  7. The Fresnel Integrals Revisited

    Science.gov (United States)

    Chen, Hongwei

    2009-01-01

    This note presents another elementary method to evaluate the Fresnel integrals. It is interesting to see that this technique is also strong enough to capture a number of pairs of parameter integrals. The main ingredients of the method are the consideration of some related derivatives and linear differential equations.

  8. 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).

  9. Optical image encryption in Fresnel domain using spiral phase transform

    Science.gov (United States)

    Kumar, Ravi; Bhaduri, Basanta

    2017-09-01

    In this study, we propose a new nonlinear optical image encryption technique using spiral phase transform (SPT). First, the primary image is phase encoded and multiplied with a random amplitude mask (RAM), and using power function, the product is then powered to m. This powered output is Fresnel propagated with distance z 1 and then modulated with a random phase mask (RPM). The modulated image is further Fresnel propagated with distance z 2. Similarly, a security image is also modulated with another RAM and then Fresnel propagated with distance z 3. Next, the two modulated images after Fresnel propagations, are interfered and further Fresnel propagated with distance z 4 to get a complex image. Finally, this complex image is SPT with particular spiral phase function (SPF), to get the final encrypted image for transmission. In the proposed technique, the security keys are Fresnel propagation distances, the security image, RPM, RAMs, power order, m, and order of SPF, q. Numerical simulation results confirm the validity and effectiveness of the proposed technique. The proposed technique is robust against noise and brutal force attacks.

  10. Solar powered desalination system using Fresnel lens

    Science.gov (United States)

    Sales, M. T. B. F.

    2016-11-01

    The Philippines is surrounded by coastal areas and these areas can be a potential source for potable water. This study aims to design and construct a solar powered desalination system using Fresnel lens. The experimental study was conducted using polluted salt water for the sample and desalination was carried out using the designed system. The desalination system was composed of the solar concentrator, solar still and the condenser system. The Fresnel lens was made of acrylic plastic and was an effective solar concentrator. Solar stills made of dark colored glass bottles were effective in absorbing the solar energy. The condenser system made of polybutylene and polystyrene were effective in condensing the vapor at ambient temperature. The shortest time of vaporization of the salt water was at 293 sec and the optimum angle of position of the lens was 36.42°. The amount of condensate collected was directly proportional to the amount of salt water in the solar still. The highest mean efficiency of the designed set-up was 34.82%. The water produced by the solar powered desalination system using Fresnel lens passed the standards set by WHO (World Health Organization) for drinking water.

  11. Optimization of Coherent Lidar Performance Using Graded- Reflectance Transmitter Resonator Optics in the Low Equivalent Fresnel Number Region

    Science.gov (United States)

    Tratt, D. M.

    1995-01-01

    Using a diffractive eigenmode treatment to model the laser output, we show that graded-reflectance resonator optics offer significant efficiency benefits over conventional hard-edge coupled unstable resonators in the context of coherent detection lidar applications. Extending previous work pertinent to the high equivalent Fresnel number regime, we have modelled the optimum performance of a notional super-Gaussian coupled cavity as a function of the key resonator parameters in the low equivalent Fresnel number regime.

  12. 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).

  13. 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

  14. 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.

  15. Methodology for the thermal characterization of linear Fresnel collectors: Comparative of different configurations and working fluids

    Science.gov (United States)

    Montes, María José; Abbas, Rubén; Rovira, Antonio; Muñoz-Antón, Javier; Martínez-Val, José María

    2017-06-01

    Linear Fresnel collectors are becoming an attractive option to generate electricity from solar radiation. This paper is focused in the thermal performance of Fresnel collectors working with different heat transfer fluids: synthetic oil, water-steam, molten salt and air, also comparing the results of the Fresnel technology with those obtained in reference parabolic trough loops. Although there are two basic designs of the Fresnel receiver: multi-tube and single-tube with secondary concentrator, this work only studies in depth the single-tube option, as this design is more suitable for a proper comparison with parabolic troughs. The receiver in parabolic troughs has been modeled as an evacuated tube with a selective coating and a glass cover. For Fresnel receivers it has been simulated two different configurations: non-evacuated receiver, with a glass window at the cavity aperture and evacuated receiver, characterized by a tube with a glass cover and a selective coating.

  16. 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)

  17. 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.

  18. Theoretical study of the crossover into hydrodynamic regime in graphene

    Science.gov (United States)

    Ho, Derek; Yudhistira, Indra; Hu, Ben Yu-Kuang; Adam, Shaffique

    Experiments on graphene have recently succeeded in entering the hydrodynamic regime, as demonstrated by successful observations of strong violation of Wiedemann-Franz law, the Gurzhi effect and electronic Poiseuille flow. It is known that electronic systems enter the hydrodynamic regime when electron-electron scattering dominates over electron-impurity and electron-phonon scattering. However, a quantitative study of this transition from the Fermi liquid to hydrodynamic regime is still lacking. In view of this, we quantitatively analyze the electron-electron, electron-impurity and electron-phonon scattering rates as a function of temperature, charge doping and disorder (charge puddle) strength. This yields a quantitative understanding of the onset of hydrodynamic electronic behavior in graphene samples. This work is supported by the National Research Foundation of Singapore under its Fellowship program (NRF-NRFF2012-01) and by the Singapore Ministry of Education and Yale-NUS College through Grant No. R-607-265-01312.

  19. 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

  20. 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.

  1. Comparison of Fresnel concentrators for building integrated photovoltaics

    International Nuclear Information System (INIS)

    Chemisana, Daniel; Ibanez, Manuel; Barrau, Jerome

    2009-01-01

    To develop concentrating photovoltaic systems for building integration applications, two optical devices are proposed. The concentrators are based in stationary linear Fresnel lenses and secondary CPC. The moving focal area is ten times smaller than the Fresnel lens aperture. Concentrator characteristics are studied in detail: shadowing effect, placement of the focal area and optical concentration efficiency. The main contribution of this paper is the three-dimensional optical analysis of the non-imaging concentrating systems. In terms of solar radiation, photovoltaic moving modules placed in the focal area of stationary concentrators are compared with simply fixed photovoltaic modules. In favourable weather locations, the beam radiation incident on the concentrating modules would be a large percentage, more than 50%, of the global radiation received by the fixed photovoltaic devices

  2. 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

  3. Fresnel diffraction plates are simple and inexpensive

    Science.gov (United States)

    Hoover, R. B.

    1967-01-01

    Fresnel plate demonstrates diffraction phenomena simply and inexpensively. A large number of identical diffracting apertures are made in random orientation on photographic film. When a small source of light is viewed through the plate, the diffraction pattern typical of the diffracting aperture is readily seen.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Rehabilitation regimes based upon psychophysical studies of prosthetic vision

    Science.gov (United States)

    Chen, S. C.; Suaning, G. J.; Morley, J. W.; Lovell, N. H.

    2009-06-01

    Human trials of prototype visual prostheses have successfully elicited visual percepts (phosphenes) in the visual field of implant recipients blinded through retinitis pigmentosa and age-related macular degeneration. Researchers are progressing rapidly towards a device that utilizes individual phosphenes as the elementary building blocks to compose a visual scene. This form of prosthetic vision is expected, in the near term, to have low resolution, large inter-phosphene gaps, distorted spatial distribution of phosphenes, restricted field of view, an eccentrically located phosphene field and limited number of expressible luminance levels. In order to fully realize the potential of these devices, there needs to be a training and rehabilitation program which aims to assist the prosthesis recipients to understand what they are seeing, and also to adapt their viewing habits to optimize the performance of the device. Based on the literature of psychophysical studies in simulated and real prosthetic vision, this paper proposes a comprehensive, theoretical training regime for a prosthesis recipient: visual search, visual acuity, reading, face/object recognition, hand-eye coordination and navigation. The aim of these tasks is to train the recipients to conduct visual scanning, eccentric viewing and reading, discerning low-contrast visual information, and coordinating bodily actions for visual-guided tasks under prosthetic vision. These skills have been identified as playing an important role in making prosthetic vision functional for the daily activities of their recipients.

  10. 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

  11. Langmuir probe study in the nonresonant current drive regime of ...

    Indian Academy of Sciences (India)

    Abstract. Characterization of the current drive regime is done for helicon wave- generated plasma in a torus, at a very high operating frequency. A radiofrequency- compensated Langmuir probe is designed and used for the measurement of plasma parameters along with the electron energy distributions in radial scans of the ...

  12. Welfare state regimes, health and health inequalities in adolescence: a multilevel study in 32 countries.

    Science.gov (United States)

    Richter, Matthias; Rathman, Katharina; Nic Gabhainn, Saoirse; Zambon, Alessio; Boyce, William; Hurrelmann, Klaus

    2012-07-01

    Comparative research on health and health inequalities has recently started to establish a welfare regime perspective. The objective of this study was to determine whether different welfare regimes are associated with health and health inequalities among adolescents. Data were collected from the 'Health Behaviour in School-aged Children' study in 2006, including 11- to 15-year-old students from 32 countries (N = 141,091). Prevalence rates and multilevel logistic regression models were calculated for self-rated health (SRH) and health complaints. The results show that between 4 per cent and 7 per cent of the variation in both health outcomes is attributable to differences between countries. Compared to the Scandinavian regime, the Southern regime had lower odds ratios for SRH, while for health complaints the Southern and Eastern regime showed high odds ratios. The association between subjective health and welfare regime was largely unaffected by adjusting for individual socioeconomic position. After adjustment for the welfare regime typology, the country-level variations were reduced to 4.6 per cent for SRH and to 2.9 per cent for health complaints. Regarding cross-level interaction effects between welfare regimes and socioeconomic position, no clear regime-specific pattern was found. Consistent with research on adults this study shows that welfare regimes are important in explaining variations in adolescent health across countries. © 2012 The Authors. Sociology of Health & Illness © 2012 Foundation for the Sociology of Health & Illness/Blackwell Publishing Ltd.

  13. A study on the development of nuclear policy to respond to international non-proliferation regimes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byung Wook; Oh, K. B.; Yang, M. H.; Lee, H. M.; Ko, H. S.; Ryu, J. S.; Jung, W. H.; Lim, C. Y

    2006-01-15

    This study analyzed the trends of the nonproliferation regimes in the following three aspects. First, this study analyzed the trends of the international nuclear non-proliferation regime, which includes the NPT, the IAEA safeguards system, the international nuclear export control regime and multilateral nuclear approach. Second, this study forecast the future trends of the nonproliferation systems with the reflection of current international situations. Third, this study also analyzed outstanding issues in nuclear control regimes and derived some factors to reflect national nuclear foreign policy.

  14. Fresnel Prism on Hess Screen Test

    OpenAIRE

    Koh, Kyung Min; Samuel Kim, Ungsoo

    2013-01-01

    A 65-year-old male patient complained of diplopia after a cataract surgery. He had esotropia of 18 prism diopters (PDs) at distant and near deviation, and therefore, we performed the Hess screen test to identify any abnormal eye movement. However, the indicator was found to be out of bounds, and therefore, the test could not be completed. Therefore, the test was subsequently performed with a 20 PD base-out Fresnel prism, and an abduction deficit was observed in the right eye, but not in the l...

  15. Solar Tracking Error Analysis of Fresnel Reflector

    Directory of Open Access Journals (Sweden)

    Jiantao Zheng

    2014-01-01

    Full Text Available Depending on the rotational structure of Fresnel reflector, the rotation angle of the mirror was deduced under the eccentric condition. By analyzing the influence of the sun tracking rotation angle error caused by main factors, the change rule and extent of the influence were revealed. It is concluded that the tracking errors caused by the difference between the rotation axis and true north meridian, at noon, were maximum under certain conditions and reduced at morning and afternoon gradually. The tracking error caused by other deviations such as rotating eccentric, latitude, and solar altitude was positive at morning, negative at afternoon, and zero at a certain moment of noon.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Diamond Machining of Optical Structured Surfaces Using a Circular Fresnel Lens as an Example

    Directory of Open Access Journals (Sweden)

    S. V. Grubyi

    2017-01-01

    Full Text Available Components of optical systems for various purposes include optical elements with structured surfaces, i.e. linear and circular Fresnel lenses. The objective of the conducted studies is to analyse design parameters and technological development of modes and conditions to ensure manufacturing circular Fresnel lenses with specified technology requirements.The subject of the study is a circular Fresnel lens, which has a thickness of 2 mm and a diameter of 76.7 mm; its processed profile consists of 126 concentric rings with a valley pitch equal to 0.3 mm. The profile depth of the rings varies from 2.1μm to 337.4μm, with the profile angle varying from 0.406 ° to 48.361 °. The lens material is polymethyl methacrylate (PMMA - a tough amorphous polymer, which has high transparency, weather resistance, good physical-mechanical and electrical insulating properties.The article presents the results of applied research related to diamond machining of a Fresnel circular lens. Substantiates that there is a need to use an ultra-precise machine for lens processing and gives its main technical characteristics.The design features and recommended domestic and foreign diamond mono-crystalline cutters for preliminary and finishing processing of structured surfaces, including Fresnel lenses are analysed.The technology of diamond edge cutting machining of lenses is proposed, the modes and conditions of diamond turning to exclude finning are given.The results of metrological control have confirmed the requirements for the profile accuracy and the roughness of surfaces machined. The JSC "VNIIINSTRUMENT" has implemented the developed technology on the ultra-precise specialised NC machine and recommended its use in machining the structured plexiglass surfaces of various sizes for different purposes.

  1. 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

  2. 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.

  3. 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.

  4. Compared performance of fresnel-based concentrators at array level

    OpenAIRE

    Mohedano del Pozo, Raúl; Cvetkovic, Aleksandra; Benitez Gimenez, Pablo; Chaves, Julio; Zamora Herranz, Pablo; Miñano Dominguez, Juan Carlos; Hernández Sanz, Maikel; Buljan, Marina

    2010-01-01

    At module level (one single solar cell), the Fresnel-Köhler (FK) concentrator comprises a perfect irradiance uniformity along with quite high concentration-acceptance angle product and loose manufacturing tolerances. At the same time, it maintains the efficiency/simplicity of other Fresnel-based concentrators. All these facts, along with the pill-box shape of its transmission curve, permit an enhanced performance of this device, compared to its competitors, at array level, because the system ...

  5. 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%.

  6. 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.

  7. Optical modeling of Fresnel zoneplate microscopes.

    Science.gov (United States)

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

    2011-07-10

    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. © 2011 Optical Society of America

  8. 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.

  9. Optical Trapping of Beads and Jurkat Cells Using Micromachined Fresnel Zone Plate Integrated with Microfluidic Chip

    Science.gov (United States)

    Kuo, Ju-Nan; Hu, Han-Zhong

    2011-10-01

    This paper presents a method for trapping beads and cells using a single-beam optical tweezer and a Fresnel zone plate integrated with a microfluidic chip. The experimental results show that a laser power of 2.4 mW is sufficient to trap 3-µm-diameter polystyrene beads, while a laser power of 1.5 mW is sufficient to trap individual Jurkat cells. The Fresnel zone plate developed in this study has many advantages, including a small size, a straightforward fabrication process, and a simple integration with microfluidic chips. Consequently, it provides an ideal solution for the trapping of a wide range of biological cells for analysis purposes.

  10. Development of the Cosmic Ray Air Fluorescence Fresnel lens Telescope for a Next Generation UHECR Observatory

    Science.gov (United States)

    Tameda, Yuichiro; Tomida, Takayuki; Hayashi, Motoki; Yamamoto, Mashu; Ikeda, Daisuke; Fujii, Toshihiro

    In near future, it is expected that sources of ultra-high-energy cosmic rays (UHECRs) can be identified, because the Telescope Array experiment reported that there is a hotspot in the UHECR arrival direction. However, it is required to observe UHECRs with higher statistics. Moreover, the mass composition should be determined, which is important information for anisotropy study. Then, we should extend the scale of observatory with fluorescence detectors which can observe Xmax, but they cost about ten times higher than particle detectors at the ground considering duty cycle. In order to reduce the cost, we are developing the Cosmic Ray Air Fluorescence Fresnel lens Telescope (CRAFFT) which is a simple structure fluorescence detector consisting of a plastic Fresnel lens of 1 m2 and a 8-in. photomultiplier tube. We succeeded to observe laser events as psudeo air shower events. In this presentation, we report the current status of development and test observation.

  11. 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

  12. 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

  13. Parametric instabilities study in a shock ignition relevant regime

    Science.gov (United States)

    Cecchetti, C. A.; Giulietti, A.; Koester, P.; Labate, L.; Levato, T.; Gizzi, L. A.; Antonelli, L.; Patria, A.; Batani, D.; Kozlová, M.; Margarone, D.; Nejdl, J.; Rus, B.; Sawicka, M.; Lafon, M.; Ribeyre, X.; Schurtz, G.

    2011-06-01

    Inertial Confinement Fusion with Shock Ignition relies on a very strong shock created by a laser pulse at an intensity of the order of 1016W/cm2. In this context, an experimental campaign at the Prague Asterix Laser System (PALS) has been carried out within the frame of the HiPER project. Two beams have been used, the first to create an extended preformed plasma (scale length of the order of hundreds of micrometers) on a planar target, the second to generate a strong shock wave. Different diagnostics were used to study both the shock breakout at the rear surface of the target and the laserplasma coupling and parametric instabilities. This paper is focused on back-scattering analysis to measure the backreflected energy and to characterize parametric instabilities such as stimulated Brillouin and Raman scattering. Our experimental data show that parametric instabilities do not play a strong role in the laser plasma coupling. Moreover, preliminary analysis of the back reflected light from the interaction region shows that less than 5% of the total incident laser energy was back-reflected, with only a small fraction of that light was originating from parametric instabilities.

  14. 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

  15. Experimental Study on Boiling Regime During Quenching Process in Heated Rod Bundle Queen

    International Nuclear Information System (INIS)

    J, Mulya; Antariksawan, A.R.; PW, Joko; S, Edy; H, Khairul; H, Ismu; Kiswanta; Giarno

    2003-01-01

    Following loss-of-coolant accident in light water reactor, the emergency core cooling must be injected. During flooding the core, the fuel cladding quenching occurred. The fuel quenching velocity is key factor for reactor safety. Various parameter influence the quenching velocity. It can also be related to the boiling regime change during transient. Current experimental study is performed to observe and apprehend boiling regime during quenching process and to measure its velocity. Experiment is conducted using Queen heated rod bundle. The quenching occurred from bottom flooding with flow rate of 0.0417 kg/s. The initial temperature of heated rod varies from 334 o C at zero point and 499 o C at top of heated zone. The visual observation method and rod surface temperature measurements is used to discus the change of boiling regime and quench front velocity. From the observation, it is obvious that at a one defined point, the boiling regime change from film boiling to single phase convection. On the other hand, the quench front velocity was affected by surface temperature and boiling regime. At the heated zone and at the beginning of quench, the quench front velocity was relatively low. While the surface temperature decreases, the quench front velocity was increase until all vapor film collapse. The average quench front velocity is about 11.5 mm/s

  16. 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.

  17. Optical loss due to diffraction by concentrator Fresnel lenses

    International Nuclear Information System (INIS)

    Hornung, Thorsten; Nitz, Peter

    2014-01-01

    Fresnel lenses are widely used in concentrating photovoltaic (CPV) systems as a primary optical element. They focus sunlight on small solar cells or on the entrance apertures of secondary optical elements. A Fresnel lens consists of several prism rings and diffraction by these prism rings is unavoidable. Some of the light that would reach a designated target area according to geometric optics will miss it due to diffraction. This diffraction loss may be of relevant magnitude for CPV applications. The results of published analytical calculations are evaluated, discussed, and compared to computer simulations and measurements

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

    CERN Document Server

    Bulava, John; Hou, George W.S.; Jansen, Karl; Knippschild, Bastian; Lin, C.J.David; Nagai, Kei-Ichi; Nagy, Attila; Ogawa, Kenji; Smigielski, Brian

    2011-01-01

    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.

  19. 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.

  20. Theoretical and experimental study of inverted annular film boiling and regime transition during reflood transients

    Science.gov (United States)

    Mohanta, Lokanath

    The Loss of Coolant Accident (LOCA) is a design basis accident for light water reactors that usually determines the limits on core power. During a LOCA, film boiling is the dominant mode of heat transfer prior to the quenching of the fuel rods. The study of film boiling is important because this mode of heat transfer determines if the core can be safely cooled. One important film boiling regime is the so-called Inverted Annular Film Boiling (IAFB) regime which is characterized by a liquid core downstream of the quench front enveloped by a vapor film separating it from the fuel rod. Much research have been conducted for IAFB, but these studies have been limited to steady state experiments in single tubes. In the present work, subcooled and saturated IAFB are investigated using high temperature reflood data from the experiments carried out in the Rod Bundle Heat Transfer (RBHT) test facility. Parametric effects of system parameters including the pressure, inlet subcooling, and flooding rate on the heat transfer are investigated. The heat transfer behavior during transition to Inverted Slug Film Boiling (ISFB) regime is studied and is found to be different than that reported in previous studies. The effects of spacer grids on heat transfer in the IAFB and ISFB regimes are also presented. Currently design basis accidents are evaluated with codes in which heat transfer and wall drag must be calculated with local flow parameters. The existing models for heat transfer are applicable up to a void fraction of 0.6, i.e. in the IAFB regime and there is no heat transfer correlation for ISFB. A new semi-empirical heat transfer model is developed covering the IAFB and ISFB regimes which is valid for a void fraction up to 90% using the local flow variables. The mean absolute percentage error in predicting the RBHT data is 11% and root mean square error is 15%. This new semi-empirical model is found to compare well with the reflood data of FLECHT-SEASET experiments as well as data

  1. Gender, health inequalities and welfare state regimes: a cross-national study of 13 European countries

    NARCIS (Netherlands)

    Bambra, C.; Pope, D.; Swami, V.; Stanistreet, D.; Roskam, A.; Kunst, A.; Scott-Samuel, A.

    2009-01-01

    BACKGROUND: This study is the first to examine the relationship between gender and self-assessed health (SAH), and the extent to which this varies by socioeconomic position in different European welfare state regimes (Liberal, Corporatist, Social Democratic, Southern). METHODS: The EUROTHINE

  2. Study of ion oscillations in a beam-plasma system in regimes of very low pressure

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.E.F.; Cabral, J.A.C.

    1982-03-01

    The ion oscillations that are excited with f approx. = f/sub ci/ in a beam-plasma system in very low pressure regimes were studied. The oscillations propagate in the azimuthal direction (k/sub z/=0) in the m=1 mode and are excited due to convection effects associated with a rotation of the plasma column.

  3. 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.

  4. A Fresnel lenses based concentrated PV system in a greenhouse

    NARCIS (Netherlands)

    Sonneveld, P.J.; Swinkels, G.L.A.M.; Tuijl, van B.A.J.; Janssen, H.J.J.; Gieling, T.H.

    2011-01-01

    The scope of this investigation is the development and testing of a new type of greenhouse with an integrated linear Fresnel lens, receiver module and an innovative system for tracking to exploit all direct radiation in a solar energy system. The basic idea of this horticultural application is to

  5. 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

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

    NARCIS (Netherlands)

    B.A.J. van Tuijl; H.J.J. Janssen; H.F. de Zwart; Piet Sonneveld; Gert-Jan Swinkels

    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

  7. 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.

  8. Polarization-controlled luminaires utilizing multiple Fresnel reflections

    Science.gov (United States)

    Falicoff, Waqidi; Minano, Juan C.; Caulfield, H. John; Alvarez, Roberto

    2003-11-01

    A novel luminaire utilizes repeated Fresnel reflections by angled surfaces to transform a small collimated input beam into a controlled output pattern with a high degree of polarization, either linear or radial. Applications to backlighting, front-lighting, optical communications and automotive lighting will be discussed.

  9. Tribological study of an aerodynamic thrust bearing in the supersonic regime

    Science.gov (United States)

    Dupuy, F.; Bou-Saïd, B.; Garcia, M.

    2017-02-01

    Nowadays, aerodynamic air thrust bearing are mainly used over a large panel of turbo-machineries. These systems become increasingly faster and up to operate in supersonic regime. They have not reached a sufficient level of research in terms of high speed. The possibility of an aerodynamic thrust bearing operating in a supersonic regime is studied. First, the air film dynamic study for high Reynolds number is based on the “modified Reynolds” equations, which take into account the inertia terms, the viscosity’s variation in the film thickness, and the turbulence. It’s an extension of the traditional model used in lubrication called the generalized Reynolds equation. The results show that a depression occur at the location of the change of slope of the tapper flat geometry. The hypothesis of presence of shock or rarefaction waves shows that the pressure gradient in the film thickness may be no longer negligible. The modified Reynolds equation may be not enough to describe the problem. A new system is built to study these phenomena: the Navier-Stokes equation are adapted to the film’s geometry. The dynamic air film’s behavior study in supersonic regime requires a shock capturing scheme called WENO scheme (“Weighted Essentially Non Oscillatory”), mainly used in shock and turbulence studies. The numerical results give the film behavior modelling of a fixed air thrust bearing pad. The evolution of the quantities shows that shock wave can occur in a thin film.

  10. Bifurcation of Health Policy Regimes: A Study of Sleep Apnea Care and Benefits Coverage in Saskatchewan.

    Science.gov (United States)

    Marchildon, Gregory P; Beck, Caroline A; Katapally, Tarun R; Abonyi, Sylvia; Dosman, James A; Episkenew, Jo-Ann

    2017-05-01

    A complex, poorly understood bifurcated health policy regime exists for Canada's First Nations people for extended health benefits coverage. This research adds to a small body of literature on the regime's impact on access and quality of care and its role in perpetuating health inequities in First Nations populations. Using a case study of sleep apnea care in Saskatchewan, we identified issues of health service access and coverage through a literature review of extended benefits programs, legislation and policies and through 10 key informant interviews with federal and provincial extended benefit program administrators and sleep medicine physicians. Important access and coverage differences were found for First Nations populations, many of which were recognized by federal and provincial policy makers. Despite these, government respondents recommended few policy ameliorations, perhaps due to system complexities, constitutional constraints or political sensitivities. We suggest three policy options to ameliorate current hardships wrought by this policy bifurcation. Copyright © 2017 Longwoods Publishing.

  11. Fresnel analysis of Kretschmann geometry with a uniaxial crystal layer on a three-layered film

    Directory of Open Access Journals (Sweden)

    Yu-Ju Hung

    2016-04-01

    Full Text Available The use of total internal reflection within the prism coupling scheme is a simple approach to the generation of surface plasmon polariton waves on a metal/dielectric interface. Unfortunately, an anisotropic layer on a metallic film complicates the derivation of resonance angle. In this study, we present clear Fresnel analysis of a liquid crystal film on a metal surface. Few current simulation packages enable the analysis of multiple layers with a single anisotropic layer. The proposed formulation process is applicable to multi-layered structures.

  12. 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.

  13. Diffusion approximation of the radiative-conductive heat transfer model with Fresnel matching conditions

    Science.gov (United States)

    Chebotarev, Alexander Yu.; Grenkin, Gleb V.; Kovtanyuk, Andrey E.; Botkin, Nikolai D.; Hoffmann, Karl-Heinz

    2018-04-01

    The paper is concerned with a problem of diffraction type. The study starts with equations of complex (radiative and conductive) heat transfer in a multicomponent domain with Fresnel matching conditions at the interfaces. Applying the diffusion, P1, approximation yields a pair of coupled nonlinear PDEs describing the radiation intensity and temperature for each component of the domain. Matching conditions for these PDEs, imposed at the interfaces between the domain components, are derived. The unique solvability of the obtained problem is proven, and numerical experiments are conducted.

  14. Self-detection of x-ray Fresnel transmissivity using photoelectron-induced gas ionization

    OpenAIRE

    Stoupin, Stanislav

    2015-01-01

    Electric response of an x-ray mirror enclosed in a gas flow ionization chamber was studied under the conditions of total external reflection for hard x-rays. It is shown that the electric response of the system as a function of the incidence angle is defined by x-ray Fresnel transmissivity and photon-electron attenuation properties of the mirror material. A simple interpretation of quantum yield of the system is presented. The approach could serve as a basis for non-invasive in-situ diagnosti...

  15. 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

  16. 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

  17. 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)

  18. 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

  19. 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)

  20. 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.

  1. New decomposition of the Fresnel operator corresponding to the optical transformation in ABCD-systems

    International Nuclear Information System (INIS)

    Du Jian-Ming; Fan Hong-Yi

    2013-01-01

    By virtue of the coherent state representation of the newly introduced Fresnel operator and its group product property, we obtain new decomposition of the Fresnel operator as the product of the quadratic phase operator, the squeezing operator, and the fractional Fourier transformation operator, which in turn sheds light on the matrix optics design of ABCD-systems. The new decomposition for the two-mode Fresnel operator is also obtained by the use of entangled state representation

  2. 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.

  3. Fresnel lens solar concentrator design and spectral distribution on focus surface

    Science.gov (United States)

    Shen, Zuo Chun; Lu, Yu; Lu, Jian Ye

    2011-09-01

    It is necessary to analysize the spectral distribution of sun light on focal spot as well as its condenser ratio, both in the study of the different quantum efficiency of photoelectric materials and the different spectral absorption coefficient for the laser medium. Based on the absorption spectrum of Cr/Nd:YAG ceramic, this paper addresses itself to the study of convex Fresnel lens focus solar light and choose spectrum. Set Parameters which are used for the design of Fresnel lens such as the ring width, height the focal length as well as the design of spectrum can be changed and the spectral ditribution on focal plane can be controlled. By way of simulation, a method through which is the best optical design for matching Cr/Nd:YAG ceramic absorption spectrum can be found. The maximum absorb power density in six optimum design is 288.5 W/cm2, which is 3.2-18.5% higher than absorb power density in six initial design based on purpose of obtaining the maximum power density.

  4. Comparison of two photosensitizers in photodynamic therapy using light pulses in femtosecond regime: an animal study

    Science.gov (United States)

    Grecco, Clóvis; Pratavieira, Sebastião.; Bagnato, Vanderlei; Kurachi, Cristina

    2016-03-01

    Photodynamic therapy is a therapeutic modality for cancer treatment based on the interaction of light with a sensitizer agent and molecular oxygen present into the target cells. The aim of this study is the evaluation of photodynamic therapy using pulsed light source in the femtosecond regime through necrosis induced in healthy rat liver. The induced necrosis profile with CW laser and pulsed laser were evaluated in animal model, which received Photodithazine (chlorine e6 derivative). The light sources used in these studies were a 660 nm CW diode laser and a Ti:Sapphire Regenerative Amplifier laser (1 kHz repetition rate and 100 fs pulse width) associated with an optical parametric amplifier (OPA) to convert to 660 nm. The results were compared with a previous study when was used a hematoporphyrin derivative (Photogem) as a sensitizer. The induced necrosis with Photogen was greater with pulsed laser (2.0 +/- 0.2 mm) in comparison with CW laser (1.0 ± 0.2 mm), while in Photodithazine the induced necrosis with was greater with CW laser (2.9 +/- 0.2 mm) comparing the pulsed laser (2.0 +/- 0.2 mm). These results indicate dependence of PDT mechanisms with photosensitizer and the light regime applied.

  5. 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.

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

    International Nuclear Information System (INIS)

    Fernández-Núñez, Isabel; Bulashenko, Oleg

    2017-01-01

    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.

  7. 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.

  8. The fast Fresnel diffraction algorithm: from the ray matrix approach to experimental virtual propagation systems

    Science.gov (United States)

    Davis, Jeffrey A.; Cottrell, Don M.; Berg, Cassidy A.; Freeman, Christopher Li; Carmona, Adriana; Debenham, William; Moreno, Ignacio

    2015-09-01

    In this paper the fast Fresnel diffraction algorithm is reviewed and applied to some novel applications. The algorithm (also named the convolution or angular spectrum method) is a very powerful numerical technique that has been employed in the calculation of diffraction patterns. It utilizes two Fourier transform operations, thus becoming computationally much faster than the conventional approach. We analyze the practical implementation with spatial light modulators (SLM). First, the ray matrix approach is applied to derive and reexamine this computational technique. This approach easily allows us to find explicit expressions for the maximum and minimum distances over which the algorithm is accurate. Then, we describe the practical implementation of this algorithm to encode Fresnel propagated masks onto a SLM. We discuss the limitations caused by the Nyquist limit. Finally, we apply the technique to create an experimental virtual optical beam propagator system. This system uses one SLM and allows the experimental study of the beam propagation without physically moving any element. This laboratory propagator system can be extremely useful to build compact optical architectures or to emulate beam propagation without misalignments caused by moving elements in the experimental system. As examples, we design holograms capable of producing different patterns at different distances, and we can change the effective plane of observation by changing the encoded propagation. The technique can find applications in many different contexts, including the analysis of propagation dynamics of nondiffracting beams, and Airy beams.

  9. 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.

  10. 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

  11. STUDY OF PARAMETERS OF THE ICE-THERMAL REGIME OF LAKE BAIKAL USING REMOTE METHODS

    Directory of Open Access Journals (Sweden)

    E. N. Sutyrina

    2017-01-01

    Full Text Available The surface temperature of the water and the characteristics of the ice cover are important parameters of the state of the ecosystem of the lake and one of the most important indicators that allow us to identify climate change. Dimensions of Lake Baikal with an area of 31.7 thousand sq. kilometers make it reasonable to use the data of satellite remote sensing to study the characteristics of its ice-thermal regime. The purpose of this investigation was to study the features of the spatiotemporal distribution of the parameters of the ice-thermal regime of Lake Baikal using AVHRR (Advanced Very High Resolution Radiometer radiometer data for the period of 1998-2016.The paper describes the developed approach to mapping the stages of melting and destruction of the snow-ice cover on Baikal Lake in the spring and the method for mapping the surface temperature of the lake in an ice-free period according to AVHRR data. Samples of compiled schematic maps of the ice situation and of temperature distribution on the lake surface are given. Based on the obtained cartographic materials, the specificity of ice disappearance of the water areas of the Southern, Central and Northern basins of Lake Baikal has been studied. And it was found that the interannual fluctuations in the timing of the ice disappearance on the given water areas are in antiphase with the interannual fluctuations in the value of the Arctic Oscillation Index. Schematic temperature maps were used to study the intra-annual and interannual variability in the temperature distribution of Lake Baikal’s surface and it was revealed that the greatest interannual variability of temperature on its surface is observed in August, which is characterized by the maximum warming of the surface of the water body. Also, the contribution of several significant factors to the formation of temperature fields on the surface of Lake Baikal was estimated. 

  12. Results and Comparison from the SAM Linear Fresnel Technology Performance Model: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, M. J.

    2012-04-01

    This paper presents the new Linear Fresnel technology performance model in NREL's System Advisor Model. The model predicts the financial and technical performance of direct-steam-generation Linear Fresnel power plants, and can be used to analyze a range of system configurations. This paper presents a brief discussion of the model formulation and motivation, and provides extensive discussion of the model performance and financial results. The Linear Fresnel technology is also compared to other concentrating solar power technologies in both qualitative and quantitative measures. The Linear Fresnel model - developed in conjunction with the Electric Power Research Institute - provides users with the ability to model a variety of solar field layouts, fossil backup configurations, thermal receiver designs, and steam generation conditions. This flexibility aims to encompass current market solutions for the DSG Linear Fresnel technology, which is seeing increasing exposure in fossil plant augmentation and stand-alone power generation applications.

  13. 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

  14. Synchronization of Green Algae by Light and Dark Regimes for Cell Cycle and Cell Division Studies.

    Science.gov (United States)

    Hlavová, Monika; Vítová, Milada; Bišová, Kateřina

    2016-01-01

    A synchronous population of cells is one of the prerequisites for studying cell cycle processes such as DNA replication, nuclear and cellular division. Green algae dividing by multiple fission represent a unique single cell system enabling the preparation of highly synchronous cultures by application of a light-dark regime similar to what they experience in nature. This chapter provides detailed protocols for synchronization of different algal species by alternating light-dark cycles; all critical points are discussed extensively. Moreover, detailed information on basic analysis of cell cycle progression in such cultures is presented, including analyses of nuclear, cellular, and chloroplast divisions. Modifications of basic protocols that enable changes in cell cycle progression are also suggested so that nuclear or chloroplast divisions can be followed separately.

  15. 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.

  16. 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

  17. 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...

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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)

  4. 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.

  5. Introducing CFD in the optical simulation of linear Fresnel collectors

    Science.gov (United States)

    Moghimi, M. A.; Rungasamy, A.; Craig, K. J.; Meyer, J. P.

    2016-05-01

    This paper seeks to determine whether the Finite Volume method within a commercially available Computational Fluid Dynamics (CFD) solver (ANSYS Fluent) can model radiation with comparable accuracy to a Monte Carlo ray-tracing software package (SolTrace). A detailed investigation was performed into modeling techniques that can be used to significantly reduce the optical errors traditionally associated with CFD modeling of radiation false scattering and ray effect using a simple optical test case. The strategies formulated in the first part of this paper were used to model a variety of Linear Fresnel Collector Concentrating Solar Power Plants. This paper shows that commercial CFD packages yield accurate results for line focusing concentrating solar applications and simple geometries, validating its use in an integrated environment where both optical and thermal performance of these plants can be simulated and optimized.

  6. Realization of surface plasmon polaritons by Fresnel diffraction

    Science.gov (United States)

    Aalipour, Rasoul; Esmaeilie, Shahram

    2018-01-01

    When a part of an optical wave-front experiences a sharp change in its phase, Fresnel diffraction becomes appreciable. Sharp change in phase occurs as a wave-front reflects from a surface with an abrupt change in reflectivity. We apply this concept to a modified Kretschmann configuration for coupling surface plasmon. In Kretschmann configuration a metal film is placed at the interface of two dielectric media. First medium with higher refractive index is a prism and second medium with lower refractive index can be the air or the solutions of interest. But, in our modified configuration, the metal film is coated only on one half of a specified face of the prism. When a parallel-polarized light travels from the higher refractive index medium to the lower refractive index medium with an angle θtechnique by theory and experiment.

  7. 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.

  8. 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

  9. 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

  10. 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.

  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. Comparing Dynamic Treatment Regimes Using Repeated-Measures Outcomes: Modeling Considerations in SMART Studies

    Science.gov (United States)

    Lu, Xi; Nahum-Shani, Inbal; Kasari, Connie; Lynch, Kevin G.; Oslin, David W.; Pelham, William E.; Fabiano, Gregory; Almirall, Daniel

    2016-01-01

    A dynamic treatment regime (DTR) is a sequence of decision rules, each of which recommends a treatment based on a patient’s past and current health status. Sequential, multiple assignment, randomized trials (SMARTs) are multi-stage trial designs that yield data specifically for building effective DTRs. Modeling the marginal mean trajectories of a repeated-measures outcome arising from a SMART presents challenges, because traditional longitudinal models used for randomized clinical trials do not take into account the unique design features of SMART. We discuss modeling considerations for various forms of SMART designs, emphasizing the importance of considering the timing of repeated measures in relation to the treatment stages in a SMART. For illustration, we use data from three SMART case studies with increasing level of complexity, in autism, child attention deficit hyperactivity disorder (ADHD), and adult alcoholism. In all three SMARTs we illustrate how to accommodate the design features along with the timing of the repeated measures when comparing DTRs based on mean trajectories of the repeated-measures outcome. PMID:26638988

  13. Parametric study of thermal and thermodynamic properties on pyrolysis of biomass in thermally thick regime

    International Nuclear Information System (INIS)

    Babu, B.V.; Chaurasia, A.S.

    2004-01-01

    In the present study, a simultaneous chemical kinetics and heat transfer model is used to predict the effects of the most important thermal and thermodynamic properties (thermal conductivity, heat transfer coefficient, emissivity and heat of reaction number) of the feedstock on the convective-radiant pyrolysis of biomass fuels. A finite difference pure implicit scheme utilizing the tri-diagonal matrix algorithm is employed for solving the heat transfer model equation. The Runge-Kutta fourth-order method is used for the chemical kinetics model equations. Simulations are performed considering cylindrical pellets of equivalent radius ranging from 0.003 to 0.011 m and temperatures ranging from 303 to 900 K. For conversion in the thermally thick regime (intra-particle heat transfer control), it is found that variations in the properties mainly affect the activity of the primary reactions. Sensitivity analysis is conducted to find the most dominant properties affecting the pyrolysis and found that the highest sensitivity is associated with the emissivity and thermal conductivity of the biomass. Applications of these findings in reactor design and operation are discussed. The results obtained using the improved models are in excellent agreement with the experimental data, much better than the agreement with the earlier models reported in the literature

  14. 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?

  15. Testing the limits of resistance: a 19-year study of Mediterranean grassland response to grazing regimes.

    Science.gov (United States)

    Sternberg, Marcelo; Golodets, Carly; Gutman, Mario; Perevolotsky, Avi; Ungar, Eugene D; Kigel, Jaime; Henkin, Zalmen

    2015-05-01

    A synthesis of a long-term (19 years) study assessing the effects of cattle grazing on the structure and composition of a Mediterranean grassland in north-eastern Israel is presented, with new insights into the response of the vegetation to grazing management and rainfall. We hypothesized that the plant community studied would be resistant to high grazing intensities and rainfall variability considering the combined long history of land-use and unpredictable climatic conditions where this community evolved. Treatments included manipulations of stocking densities (moderate, heavy, and very heavy) and of grazing regimes (continuous vs. seasonal), in a factorial design. The effect of interannual rainfall variation on the expression of grazing impacts on the plant community was minor. The main effects of grazing on relative cover of plant functional groups were related to early vs. late seasonal grazing. Species diversity and equitability were remarkably stable across all grazing treatments. A reduction in tall grass cover at higher stocking densities was correlated with increased cover of less palatable groups such as annual and perennial thistles, as well as shorter and prostrate groups such as short annual grasses. This long-term study shows that interannual fluctuations in plant functional group composition could be partly accounted for by grazing pressure and timing, but not by the measured rainfall variables. Grazing affected the dominance of tall annual grasses. However, the persistence of tall grasses and more palatable species over time, despite large differences in grazing pressure and timing, supports the idea that Mediterranean grasslands are highly resistant to prolonged grazing. Indeed, even under the most extreme grazing conditions applied, there were no signs of deterioration or collapse of the ecosystem. This high resistance to grazing intensity and interannual fluctuation in climatic conditions should favor the persistence of the plant community under

  16. 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.

  17. Measuring autocratic regime stability

    Directory of Open Access Journals (Sweden)

    Joseph Wright

    2016-01-01

    Full Text Available Researchers measure regime stability in autocratic contexts using a variety of data sources that capture distinct concepts. Often this research uses concepts developed for the study of democratic politics, such as leadership change or institutionalized authority, to construct measures of regime breakdown in non-democratic contexts. This article assesses whether the measure a researcher chooses influences the results they obtain by examining data on executive leadership, political authority, and autocratic regimes. We illustrate the conceptual differences between these variables by extending recent studies in the literature on the political consequences of non-tax revenue and unearned foreign income.

  18. Scanning soft x-ray microscopy with a fresnel zoneplate at the National Synchrotron Light Source

    International Nuclear Information System (INIS)

    Kenney, J.M.; Kirz, J.; Rarback, H.; Feder, R.; Sayre, D.; Howells, M.

    1983-01-01

    We have built a scanning transmission soft x-ray microscope located at the National Synchrotron Light Source (NSLS). Images of biological specimens have been formed with submicron resolution. A Fresnel zoneplate serves as the focusing element

  19. Water-filled telescopes and the pre-history of Fresnel's ether dragging.

    Science.gov (United States)

    Møller Pedersen, K.

    2000-06-01

    This essay examines the development of the optics of moving transparent bodies during the 19th century. In particular, it highlights how the discussion of stellar and terrestrial aberration influenced the formulation of Fresnel's theory of ether dragging.

  20. 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.

  1. 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

  2. Ultra-high resolution zone-doubled diffractive X-ray optics for the multi-keV regime.

    Science.gov (United States)

    Vila-Comamala, Joan; Gorelick, Sergey; Färm, Elina; Kewish, Cameron M; Diaz, Ana; Barrett, Ray; Guzenko, Vitaliy A; Ritala, Mikko; David, Christian

    2011-01-03

    X-ray microscopy based on Fresnel zone plates is a powerful technique for sub-100 nm resolution imaging of biological and inorganic materials. Here, we report on the modeling, fabrication and characterization of zone-doubled Fresnel zone plates for the multi-keV regime (4-12 keV). We demonstrate unprecedented spatial resolution by resolving 15 nm lines and spaces in scanning transmission X-ray microscopy, and focusing diffraction efficiencies of 7.5% at 6.2 keV photon energy. These developments represent a significant step towards 10 nm spatial resolution for hard X-ray energies of up to 12 keV.

  3. 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)

  4. 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.

  5. 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

  6. Study on flow parameters of fractal porous media in the high-velocity fluid flow regime

    Science.gov (United States)

    Qi, Mei; Xu, Hui; Yang, Chao; Qu, Tailai; Kong, lingxiao; Wu, Shucheng; Zeng, Baoquan; Xu, Haixia

    2017-12-01

    High-velocity fluid flow, which will result in the region of the wellbore or fracture, is generally in the turbulent flow regime and has drawn tremendous attention in petroleum engineering field. Turbulent factor is the key parameter, which is widely used to describe high-velocity flow in porous media. In this work, a theoretical model for turbulent factor in fractal porous media in the high-velocity fluid flow regime is developed. Moreover, a novel analytical expression for the permeability in porous media based on Wu's resistance model is also derived. Then, the analytical Kozeny-Carman constant with no empirical constant is obtained. The predictions of permeability-porosity relation by the current mathematical models have been validated by comparing with available experimental data. Furthermore, the effects of structural parameters of porous media on the curve of velocity and pressure drop are discussed in detail.

  7. 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.

  8. Study of the structure factor anisotropy and long range correlations of ferrofluids in the dilute low-coupling regime

    Energy Technology Data Exchange (ETDEWEB)

    Cerda, Juan J., E-mail: joan@ifisc.uib-csic.e [Instituto de Fisica Interdisciplinar y Sistemas Complejos IFISC (CSIC-UIB), Universitat de les Illes Balears, 07122 Palma de Mallorca (Spain); Institute for Computational Physics, Pfaffenwaldring 27, Universitaet Stuttgart, 70569 Stuttgart (Germany); Elfimova, Ekaterina [Department of Mathematical Physics, Urals State University, 51 Lenin Avenue, Ekaterinburg 620083 (Russian Federation); Ballenegger, V. [Institut UTINAM, Universite de Franche-Comte, Route de Gray 16, 25030 Besancon (France); Krutikova, Ekaterina; Ivanov, Alexey [Department of Mathematical Physics, Urals State University, 51 Lenin Avenue, Ekaterinburg 620083 (Russian Federation); Holm, Christian [Institute for Computational Physics, Pfaffenwaldring 27, Universitaet Stuttgart, 70569 Stuttgart (Germany)

    2011-05-15

    Dipolar soft-sphere (DSS) fluids in the dilute low-coupling regime are studied via Molecular Dynamic simulations and the extension of a theoretical formalism previously used for dipolar hard spheres in which new terms for the virial expansion of the radial distribution function corresponding to the three-particle contribution are presented and tested for the zero and non-zero magnetic field case. A thorough comparison with simulations shows that the extended formalism is able to account for the structure factors of DSS with and without externally applied magnetic fields in the dilute low-coupling regime: quantitative agreement between theory and simulations is found for dipolar coupling parameters {lambda}{<=}2, and volume fraction {phi}{<=}0.25. When {lambda}>1 the new added term to the virial expansion is observed to play a crucial role in order to match quantitatively theory and simulations at zero field. In the presence of an external magnetic field our tests show that further improvements are needed and only new terms with Langevin function dependences can significatively contribute to improve the predictions for the dilute low-coupling regime. Numerical simulations show that despite that the ferrofluids considered here are in the dilute low-coupling regime, when an external field is applied, important correlations along the parallel direction to the field and depletion phenomena along the perpendicular direction are observed in the averaged density surrounding a particle. - Research Highlights: Formalism for dipolar hard-sphere fluids extended to dipolar soft-sphere fluids. New virial coefficients derived for the zero and non-zero magnetic field cases. Simulations show the formalism to be valid in the diluted low-coupling regime (DLCR). For moderate and strong magnetic fields, further coefficients need to be derived. Simulations with applied field show significant particle correlations in the DLCR.

  9. Kr and Xe irradiations in lanthanum (La) doped ceria: Study at the high dose regime

    Science.gov (United States)

    Yun, Di; Oaks, Aaron J.; Chen, Wei-ying; Kirk, Marquis A.; Rest, Jeffrey; Insopov, Zinetula Z.; Yacout, Abdellatif M.; Stubbins, James F.

    2011-11-01

    In order to understand cavity and bubble formation and growth in oxide nuclear fuel materials, ion beam irradiation experiments were conducted with two common fission gas species: Kr and Xe. Ceria (CeO 2) was selected as a surrogate material for uranium dioxide (UO 2) due to its many similar properties to UO 2. Ion beam energies were chosen such that both cavities and gas bubbles structures were induced by ion irradiations. The ion irradiation experiments were carried out at 600 °C, at which temperature, cavity/gas bubble structures are believed to be immobile in this material. Lanthanum (La) was chosen as a dopant in CeO 2 to investigate the effect of impurities. The presence of La in the CeO 2 lattice also introduces a predictable initial concentration of oxygen vacancies, similar to the introduction of oxygen vacancies by the existence of Pu 3+ in MOX fuel [1]. The influence of two La concentrations, 5% and 25%, were examined. The study focused on the high dose regime where cavity/gas bubble structures were clearly identifiable with their sizes and number densities readily measurable. Cavity/gas bubble coarsening by coalescence was identified with TEM (Transmission Electron Microscopy) characterizations of as-irradiated La doped CeO 2 specimens. The results revealed that lanthanum trapping has significant influence on the cavity/bubble growth in the material lattice by comparing the cavity/gas bubble size distributions between 5% La doped ceria and 25% La doped ceria. Lattice and kinetic Monte Carlo calculations described in a previous work have provided insights to the interpretations of the experimental results [2]. Solid state Xe precipitates were observed in low energy Xe implantation in 5% La doped ceria to a very high fluence of 1 × 10 17 ions/cm 2 at 600 °C. The solid state Xe precipitate structures are represented by faceted morphology. Very similar observations of solid state/near solid state Xe bubbles were made by Nogita et al. in the outer region

  10. Thin Fresnel zone plate lenses for focusing underwater sound

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, David C., E-mail: david.calvo@nrl.navy.mil; Thangawng, Abel L.; Nicholas, Michael; Layman, Christopher N. [Acoustics Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2015-07-06

    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.

  11. 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

  12. 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.

  13. Thin Fresnel zone plate lenses for focusing underwater sound

    Science.gov (United States)

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

    2015-07-01

    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.

  14. 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

  15. Fresnel equations and transmission line analogues for diffraction gratings

    Energy Technology Data Exchange (ETDEWEB)

    Kaushik, S.

    1995-08-01

    A simple and intuitive formalism is presented to describe diffraction in multi-layered periodic structures. We use the well known results from scalar analysis (wave propagation in homogeneous layered media) and show that they can be generalized rather readily to vector problems such as diffraction analysis. Specifically, we derive: (1) generalized Fresnel equations appropriate for reflection and transmission from an infinitely thick grating, (2) a generalized Airy formula for thin-film to describe reflection and transmission of light through a lamellar grating and (3) a matrix propagation method akin to that used for multi-layer thin film analysis. The results developed here complement the recent work on R-matrix and S-matrix propagation algorithms that have been used in connection with modal and differential grating theories. These algorithms have proven to be numerically stable for calculating diffraction efficiencies from deep groove gratings. The formalism developed here expands upon the earlier literature by providing important details that are hitherto unavailable.

  16. 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.

  17. DOUBLY ROBUST ESTIMATION OF OPTIMAL TREATMENT REGIMES FOR SURVIVAL DATA-WITH APPLICATION TO AN HIV/AIDS STUDY.

    Science.gov (United States)

    Jiang, Runchao; Lu, Wenbin; Song, Rui; Hudgens, Michael G; Naprvavnik, Sonia

    2017-09-01

    In many biomedical settings, assigning every patient the same treatment may not be optimal due to patient heterogeneity. Individualized treatment regimes have the potential to dramatically improve clinical outcomes. When the primary outcome is censored survival time, a main interest is to find optimal treatment regimes that maximize the survival probability of patients. Since the survival curve is a function of time, it is important to balance short-term and long-term benefit when assigning treatments. In this paper, we propose a doubly robust approach to estimate optimal treatment regimes that optimize a user specified function of the survival curve, including the restricted mean survival time and the median survival time. The empirical and asymptotic properties of the proposed method are investigated. The proposed method is applied to a data set from an ongoing HIV/AIDS clinical observational study conducted by the University of North Carolina (UNC) Center of AIDS Research (CFAR), and shows the proposed methods significantly improve the restricted mean time of the initial treatment duration. Finally, the proposed methods are extended to multi-stage studies.

  18. 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.

  19. 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

  20. Continental Scientific Drilling (CSD): Technology Barriers to Deep Drilling Studies in Thermal Regimes

    Energy Technology Data Exchange (ETDEWEB)

    Kolstad, George A.; Rowley, John C.

    1987-01-16

    This report is the proceedings of a workshop. The primary thrust of these discussion was to identify the major key technology barriers to the Department of Energy (DOE) supported Thermal Regimes CSD projects and to set priorities for research and development. The major technological challenge is the high temperature to be encountered at depth. Specific problems derived from this issue were widely recognized among the participants and are reflected in this summary. A major concern for the projected Thermal Regimes CSD boreholes was the technology required for continuous coring, in contrast to that required for drilling without core or spot coring. Current commercial technology bases for these two techniques are quite different. The DOE has successfully fielded projects that used both technologies, i.e, shallow continuous coring (Inyo Domes and Valles Caldera) and deeper drilling with spot cores (Imperial Valley-SSSDP). It was concluded that future scientific objectives may still require both approaches, but continuous coring is the most likely requirement in the near term. (DJE-2005)

  1. 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.

  2. Huygens-Fresnel picture for electron-molecule elastic scattering★

    Science.gov (United States)

    Baltenkov, Arkadiy S.; Msezane, Alfred Z.

    2017-11-01

    The elastic scattering cross sections for a slow electron by C2 and H2 molecules have been calculated within the framework of the non-overlapping atomic potential model. For the amplitudes of the multiple electron scattering by a target the wave function of the molecular continuum is represented as a combination of a plane wave and two spherical waves generated by the centers of atomic spheres. This wave function obeys the Huygens-Fresnel principle according to which the electron wave scattering by a system of two centers is accompanied by generation of two spherical waves; their interaction creates a diffraction pattern far from the target. Each of the Huygens waves, in turn, is a superposition of the partial spherical waves with different orbital angular momenta l and their projections m. The amplitudes of these partial waves are defined by the corresponding phases of electron elastic scattering by an isolated atomic potential. In numerical calculations the s- and p-phase shifts are taken into account. So the number of interfering electron waves is equal to eight: two of which are the s-type waves and the remaining six waves are of the p-type with different m values. The calculation of the scattering amplitudes in closed form (rather than in the form of S-matrix expansion) is reduced to solving a system of eight inhomogeneous algebraic equations. The differential and total cross sections of electron scattering by fixed-in-space molecules and randomly oriented ones have been calculated as well. We conclude by discussing the special features of the S-matrix method for the case of arbitrary non-spherical potentials. Contribution to the Topical Issue "Low energy positron and electron interactions", edited by James Sullivan, Ron White, Michael Bromley, Ilya Fabrikant, and David Cassidy.

  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. 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.

  5. Fresnel-region fields and antenna noise-temperature calculations for advanced microwave sounding units

    Science.gov (United States)

    Schmidt, R. F.

    1982-01-01

    A transition from the antenna noise temperature formulation for extended noise sources in the far-field or Fraunhofer-region of an antenna to one of the intermediate near field or Fresnel-region is discussed. The effort is directed toward microwave antenna simulations and high-speed digital computer analysis of radiometric sounding units used to obtain water vapor and temperature profiles of the atmosphere. Fresnel-region fields are compared at various distances from the aperture. The antenna noise temperature contribution of an annular noise source is computed in the Fresnel-region (D squared/16 lambda) for a 13.2 cm diameter offset-paraboloid aperture at 60 GHz. The time-average Poynting vector is used to effect the computation.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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)

  12. Field methods for studying soil moisture regimes and irrigation practices in clay soils

    International Nuclear Information System (INIS)

    Bouma, J.

    1983-01-01

    Characterization of water flow through swelling clay soils with macropores (''cracks'') requires special techniques because these soils are not isotropic and homogeneous as required by standard flow theory. The techniques should preferably be rapid and inexpensive to allow applications in the field. Three experimental techniques, which were recently developed at the Netherlands Soil Survey Institute, are discussed. The measure: (i) vertical and horizontal Ksub(sat) in a gypsum-covered cube of soil which is carved out in situ (the cube method); (ii) the Ksub(unsat) near saturation down to pressure heads of about -15cm by determining fluxes through a series of crusts and the associated negative pressure heads below the crusts (the crusts test); and (iii) short-circuiting, which is the preferential movement of free water along vertical macropores in unsaturated soil, by applying sprinkling irrigation to large, undisturbed cores. In addition, three examples are discussed whereby soil morphological field data are used for simulation models which characterize soil moisture regimes of clay soils. These examples cover: (i) the effect of horizontal cracks on upward unsaturated flow; (ii) infiltration of sprinkling irrigation in a cracked clay soil; and (iii) ponded infiltration of water in a clay soil with worm channels. (author)

  13. 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

  14. A study of climate change impacts on hydrologic regime of the Vogršček accumulation (SW Slovenia

    Directory of Open Access Journals (Sweden)

    Branka Trček

    2005-12-01

    Full Text Available Climate change impacts on hydrologic regime of the Vogršček accumulation (Vipava valley were studied for a decade period 1995-2004. During this time water capture from the accumulation has been increased. Although a pumping did not influence the accumulationlevel a lot, it oscillated much different during single halves of the decade. The results indicated that this could result from a decrease of effective precipitation amounts, which recharge the accumulation, from changes of their distribution, as well as from an increasedfrequency of extreme dry periods and extreme precipitation events during the second decade half.

  15. Optical Image Encryption Using Devil’s Vortex Toroidal Lens in the Fresnel Transform Domain

    Directory of Open Access Journals (Sweden)

    Hukum Singh

    2015-01-01

    Full Text Available We have carried out a study of optical image encryption in the Fresnel transform (FrT domain, using a random phase mask (RPM in the input plane and a phase mask based on devil’s vortex toroidal lens (DVTL in the frequency plane. The original images are recovered from their corresponding encrypted images by using the correct parameters of the FrT and the parameters of DVTL. The use of a DVTL-based structured mask enhances security by increasing the key space for encryption and also aids in overcoming the problem of axis alignment associated with an optical setup. The proposed encryption scheme is a lensless optical system and its digital implementation has been performed using MATLAB 7.6.0 (R2008a. The scheme has been validated for a grayscale and a binary image. The efficacy of the proposed scheme is verified by computing mean-squared-error (MSE between the recovered and the original images. We have also investigated the scheme’s sensitivity to the encryption parameters and examined its robustness against occlusion and noise attacks.

  16. 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

  17. 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.

  18. A CPV system with static linear Fresnel lenses in a greenhouse

    NARCIS (Netherlands)

    Sonneveld, P.J.; Zahn, H.; Swinkels, G.L.A.M.

    2010-01-01

    A new CPV system with a static linear Fresnel lens, silicon PV module suitable for concentrated radiation and an innovative tracking system is integrated in a greenhouse covering. The basic idea of this horticultural application is to develop a greenhouse for pot plants (typical shadow plants) which

  19. 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.

  20. Design of Novel Compound Fresnel Lens for High-Performance Photovoltaic Concentrator

    Directory of Open Access Journals (Sweden)

    Lei Jing

    2012-01-01

    Full Text Available We present a new design of compound Fresnel-R concentrator which is composed of two lenses: a primary lens (Fresnel lens that works by total internal reflection at outer sawteeth but refraction at inner sawteeth, and a ringed secondary lens that works by refraction. In contrast to previous Fresnel lens concentrators, this design increases the acceptance angle, improves the irradiance uniformity on the solar cell, and reduces the aspect ratio significantly. Meanwhile several sawteeth of the primary Fresnel lens can correspond to a same ring of secondary lens, which will efficiently lower the complexity of designing and manufacturing. Moreover, in order to reduce the influence of manufacturing tolerances and to increase the optical efficiency further, the central part of the bottom of the secondary lens which directly adhered to the solar cell is designed as a cone-shaped prism to collect the sunlight that does not reach the solar cell. Finally, we provide simulations and analyses of the design method an optical efficiency more than 80% and an aspect ratio smaller than 0.5 can be achieved.

  1. The method of stationary phase and the method of Fresnel zones

    NARCIS (Netherlands)

    Kampen, N.G. van

    1958-01-01

    The method of stationary phase is discussed and reasons are given why it is often preferable to the method of steepest descent, in spite of the mathematicians' partiality to the latter. The method of Fresnel zones is compared with the method of stationary phase and is shown to be a primitive version

  2. 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.

  3. 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.

  4. Performance of a concentrated photovoltaic energy system with static linear Fresnel lenses

    NARCIS (Netherlands)

    Sonneveld, P.J.; Swinkels, G.L.A.M.; Tuijl, van B.A.J.; Janssen, H.J.J.; Campen, J.B.; Bot, G.P.A.

    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

  5. 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%.

  6. Technology of Manufacture of the Negative Matrices for Linear Fresnel Lenses

    Science.gov (United States)

    Lapshin, V. V.; Zakharevich, E. M.; Grubyy, S. V.

    2016-04-01

    This article describes the main structural features of negative matrices which are intended for the production of positive copies of linear Fresnel lenses. Linear lenses are used in a space solar energy industry as solar concentrators in the photovoltaic modules. The article covers the essential requirements which are placed on the equipment and technology for the production of such matrices.

  7. 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

  8. 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 ...

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

    Science.gov (United States)

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

    2017-05-01

    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.

  10. 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

  11. 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.

  12. 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

  13. The influence of synoptic weather regimes on UK air quality: regional model studies of tropospheric column NO2

    Science.gov (United States)

    Pope, R. J.; Savage, N. H.; Chipperfield, M. P.; Ordóñez, C.; Neal, L. S.

    2015-10-01

    Synoptic meteorology can have a significant influence on UK air quality. Cyclonic conditions lead to the dispersion of air pollutants away from source regions, while anticyclonic conditions lead to their accumulation over source regions. Meteorology also modifies atmospheric chemistry processes such as photolysis and wet deposition. Previous studies have shown a relationship between observed satellite tropospheric column NO2 and synoptic meteorology in different seasons. Here, we test whether the UK Met Office Air Quality in the Unified Model (AQUM) can reproduce these observations and then use the model to explore the relative importance of various factors. We show that AQUM successfully captures the observed relationships when sampled under the Lamb weather types, an objective classification of midday UK circulation patterns. By using a range of idealized NOx-like tracers with different e-folding lifetimes, we show that under different synoptic regimes the NO2 lifetime in AQUM is approximately 6 h in summer and 12 h in winter. The longer lifetime can explain why synoptic spatial tropospheric column NO2 variations are more significant in winter compared to summer, due to less NO2 photochemical loss. We also show that cyclonic conditions have more seasonality in tropospheric column NO2 than anticyclonic conditions as they result in more extreme spatial departures from the wintertime seasonal average. Within a season (summer or winter) under different synoptic regimes, a large proportion of the spatial pattern in the UK tropospheric column NO2 field can be explained by the idealized model tracers, showing that transport is an important factor in governing the variability of UK air quality on seasonal synoptic timescales.

  14. Study of Plasma Flows Generated in Plasma Focus Discharge in Different Regimes of Working Gas Filling

    Science.gov (United States)

    Voitenko, D. A.; Ananyev, S. S.; Astapenko, G. I.; Basilaia, A. D.; Markolia, A. I.; Mitrofanov, K. N.; Myalton, V. V.; Timoshenko, A. P.; Kharrasov, A. M.; Krauz, V. I.

    2017-12-01

    Results are presented from experimental studies of the plasma flows generated in the KPF-4 Phoenix Mather-type plasma focus device (Sukhum Physical Technical Institute). In order to study how the formation and dynamics of the plasma flow depend on the initial distribution of the working gas, a system of pulsed gas puffing into the discharge volume was developed. The system allows one to create profiled gas distributions, including those with a reduced gas density in the region of plasma flow propagation. Results of measurements of the magnetic field, flow profile, and flow deceleration dynamics at different initial distributions of the gas pressure are presented.

  15. A Study on Regime Type and Globalization in Simultaneous Equation Framework

    OpenAIRE

    SUDHANSHU K. MISHRA

    2018-01-01

    In this study we build a simultaneous equation model in which the measures of different aspects of globalization (attributable to KOF) and different aspects of democracy (attributable to EIU) are related in seven structural equations. A bi-directional relationship between democracy and globalization is visualized. The model is estimated by the conventional 2-SLS as well as a modified 2-SLS in which Shapley value regression is used at the second stage of 2-SLS. On the basis of our analysis we ...

  16. CLIMATE AND LULC CHANGE SCENARIOS TO STUDY ITS IMPACT ON HYDROLOGICAL REGIME

    Directory of Open Access Journals (Sweden)

    S. P. Aggarwal

    2012-07-01

    Full Text Available Climate change, whether as a natural cycle variability and/or due to anthropogenic reasons, is affecting and likely to further affect the water resources, which is a vital necessity for existence of life form. The predicted intensification of hydrological cycle would change all of its constituents both in time and space domain. This is a long term phenomenon and the necessity is to understand the intensity of the effects on various aspects of water resources by way of scientific studies backed by the available field data. Therefore, in the present study, the impact of climate and land use land cover change on entire India under different assumed plausible hypothetical scenarios has been studied. These scenarios were developed by increasing; temperature by 1, 2 and 30C; rainfall by 5, 10 and 15%; and then the combination of both. To carry out this analysis, variable infiltration capacity (VIC semi-distributed macroscale hydrological model has been investigated. It was found that slight change in climate may pose huge difference on hydrological cycle and its component.

  17. 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.

  18. 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)

  19. 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.

  20. A Study on Regime Type and Globalization in Simultaneous Equation Framework

    Directory of Open Access Journals (Sweden)

    SUDHANSHU K. MISHRA

    2018-01-01

    Full Text Available In this study we build a simultaneous equation model in which the measures of different aspects of globalization (attributable to KOF and different aspects of democracy (attributable to EIU are related in seven structural equations. A bi-directional relationship between democracy and globalization is visualized. The model is estimated by the conventional 2-SLS as well as a modified 2-SLS in which Shapley value regression is used at the second stage of 2-SLS. On the basis of our analysis, we document several findings. First, we find that democracy and globalization promote each other and hence there is a bi-directional causality with positive relationships running both ways between democracy and globalization. At a national level, there may be various intermediary conditions that modify the relationship as well as set in motion a complex of positive and/or negative feedbacks to accelerate or retard the pace of globalization and democratization in a country-specific manner. However, when a large number of countries are studied, a clear relationship emerges out. Second, there is a need to estimate the structural coefficients of the model cautiously since the regression equations may be suffering from collinearity among the predictor variables. The Shapley value regression based 2-SLS has performed better than the conventional regression in estimating the structural parameters of the model. Third, the system methods of estimation of the model gives better results than what are obtained by the single equation methods of estimation of structural parameters of the model.

  1. Numerical study of the motion of a flagellated swimmer inside a tube in the Stokes regime

    Science.gov (United States)

    Zhang, Ji; Jiao, Yusheng; Xu, Xinliang; Ding, Yang

    2017-11-01

    Confined environments are common to micro-swimmers such bacteria and previous studies have shown that confinements such as a wall can influenced the trajectory of the micro-swimmers. Here we study whether some micro-swimmers can achieve a higher speed and energetic efficiency within a long tube comparing to the free-space case using a numerical model. The swimmer consists of an elliptical head and two helical flagella. To solve the governing Stokes equations inside an infinite tube, we combine the method of fundamental solution (MSF) and the method of Stokeslet. The geometry parameters, including shape and size of head and flagella, and relative spatial position of these components, are varied. Our results show that the geometry of the swimmer and the tube can greatly affect the speed of the micro-swimmer. For certain geometric parameters of the micro-swimmer, a greater confinement leads to a higher speed, which is consistent with the results from our robotic experiments.

  2. Regime Change and the Role of Airpower

    National Research Council Canada - National Science Library

    Fahrenkrug, David T

    2006-01-01

    Drawing from the vision of airpower theorists and building on insights gained from studies on various regime changes, this thesis advances a theory of regime change and outlines a strategy for the use of airpower...

  3. Regime Change and the Role of Airpower

    National Research Council Canada - National Science Library

    Fahrenkrug, David

    2003-01-01

    Drawing from the vision of airpower theorists, and building on insights gained from studies on various regime changes, this thesis advances a theory of regime change and outlines a strategy for the use of airpower...

  4. 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.

  5. Usefulness and Utility of NACO Regime in the Management of Sexually Transmitted Infections: A Pilot Study.

    Science.gov (United States)

    Das, Anupam; Ghosh, Pramit; Ghosh, Ishita; Bhattacharya, Rittwika; Azad Sardar, Abul Kalam; Goswami, Sebanti; Bandyopadhyay, Debabrata; Das, Nilay Kanti

    2017-01-01

    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. The aim of this study was to evaluate the etiological agent for STI syndromes and correlate the syndromic diagnosis with etiological diagnosis. 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. 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%). 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 delay.

  6. 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

  7. 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.

  8. 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.

  9. Studying the accretion geometry of EXO 2030+375 at luminosities close to the propeller regime

    Science.gov (United States)

    Fürst, F.; Kretschmar, P.; Kajava, J. J. E.; Alfonso-Garzón, J.; Kühnel, M.; Sanchez-Fernandez, C.; Blay, P.; Wilson-Hodge, C. A.; Jenke, P.; Kreykenbohm, I.; Pottschmidt, K.; Wilms, J.; Rothschild, R. E.

    2017-10-01

    The Be X-ray binary EXO 2030+375was in an extended low-luminosity state during most of 2016. We observed this state with NuSTARand Swift, supported by INTEGRALobservations and optical spectroscopy with the Nordic Optical Telescope (NOT). We present a comprehensive spectral and timing analysis of these data here to study the accretion geometry and investigate a possible onset of the propeller effect. The Hα data show that the circumstellar disk of the Be-star is still present. We measure equivalent widths similar to values found during more active phases in the past, indicating that the low-luminosity state is not simply triggered by a smaller Be disk. The NuSTARdata, taken at a 3-78 keV luminosity of 6.8 × 1035 erg s-1 (for a distance of 7.1 kpc), are nicely described by standard accreting pulsar models such as an absorbed power law with a high-energy cutoff. We find that pulsations are still clearly visible at these luminosities, indicating that accretion is continuing despite the very low mass transfer rate. In phase-resolved spectroscopy we find a peculiar variation of the photon index from 1.5 to 2.5 over only about 3% of the rotational period. This variation is similar to that observed with XMM-Newtonat much higher luminosities. It may be connected to the accretion column passing through our line of sight. With Swift/XRT we observe luminosities as low as 1034 erg s-1 where the data quality did not allow us to search for pulsations, but the spectrum is much softer and well described by either a blackbody or soft power-law continuum. This softer spectrum might be due to the accretion being stopped by the propeller effect and we only observe the neutron star surface cooling.

  10. 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.

  11. Incorporating Climate Change in Flow Regime Alteration Studies in Hydropower Licensing

    Science.gov (United States)

    Rheinheimer, D. E.; Akhbari, M.; Peek, R.; Yarnell, S. M.; Null, S. E.; Viers, J. H.

    2013-12-01

    The U.S. Federal Energy Regulatory Commission has yet to mandate incorporation of anticipated climate change effects on hydropower system operations when assessing environmental impacts from the renewal of hydropower licenses. One stated reason is the lack of specific project-level specificity in future impacts. We demonstrate how a hydropower system operations model, incorporating the latest climatological realizations (3 GCMs x RCPs 4.5 and 8.5), can be used to assess environmental impacts generally, and hydrological flow alterations in particular, during the hydropower licensing process. We demonstrate that we can, in fact, quantify project-level impacts from climate change, albeit within the context of quantified uncertainty about non-stationary future conditions. The systems operations model analysis encompasses the combined effects of the Yuba River Development Project and Yuba-Bear Drum-Spaulding Projects, an interconnected series of complex hydropower systems located in the Sierra Nevada, California. Daily water system operations are simulated using a monthly-scale optimization model for hydropower decisions. Though there is inherent uncertainty generated by the modeling process and operational assumptions (e.g., static energy demand), there are sufficient data, modeling techniques, and analytical approaches to assess the how management decisions made today may be confounded by non-stationary hydroclimates in 30-50 years, which is the duration of most hydropower licenses. Such decisions need to include adaptive management approaches to address not only non-stationary hydroclimates, but also cumulative impacts to ecological functions and processes caused by serial flow manipulation. This study can help provide the scientific guidance needed to improve climate change policy in hydropower system planning.

  12. A Comparative Study of Finite Journal Bearing in Laminar and Turbulent Regimes Using CFD (Computational Fluid Dynamic

    Directory of Open Access Journals (Sweden)

    Susilowati

    2016-01-01

    Full Text Available In this paper, an investigation of hydrodynamic performance for journal bearing lubricated by thin film is performed by three-dimensional CFD (computational fluid dynamic. Two regimes, i.e. laminar and turbulent regimes are of main interest. The sliding velocity was varied from 3000, 5000 and 10000. The numerical simulation shows that the velocity magnitude of the journal has a strong effect on the hydrodynamic pressure. In addition, it is found that an appropriate modelling of flow regime affects the predicted lubrication performance. From the overall analysis, both using laminar and turbulent regimes, the distribution of static hydrodynamic pressure shows a similar trend. It is also found that at the beginning of the contact, the static pressure is low, and then, it gradually increases to the highest point, and finally drops significantly.

  13. 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

  14. Suppression of interference noise caused by Fresnel reflection in all-fiber white-light interferometer.

    Science.gov (United States)

    Yuan, Yonggui; Cheng, Yongqing; Yang, Jun; Zhang, Haoliang; Lu, Dongchuan; Lv, Yan; Peng, Feng; Li, Hanyang; Zhang, Xiaojun; Jiang, Fuqiang; Yuan, Libo

    2017-11-01

    We propose methods to suppress the interference noise (IN) of an all-fiber white-light interferometer (WLI), which is caused by the residual Fresnel reflective beam. The methods are proposed to ensure a wide dynamic range and enhance the accuracy of measurement. IN can cause misjudgment of the realistic optical characteristic parameters, such as the fault diagnosis and polarization coupling of the optical devices under test. In addition, IN can reduce the dynamic range of the WLI. The optical path mismatch (OPM) method and the intensity suppression (IS) method by changing the positions and intensity of the IN are presented. The two suppression methods can successfully restrain IN caused by the Fresnel reflection beams. The experimental results show that IN is successfully suppressed by the OPM method or restrained by IS method in interferograms, and the dynamic range can achieve 85 dB without IN.

  15. 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)

  16. Water-Filled Telescopes and the Pre-History of Fresnel's Ether Dragging

    DEFF Research Database (Denmark)

    Pedersen, Kurt Møller

    2000-01-01

    The idea of measuring stellar aberration with a water-filled telescope was entertained from the middle of the 18th century by Thomas Melvill, Patrick Wilson, Roger Joseph Boscovich, and John Robison. I shall discuss their ideas as well as those discussed by Thomas Young, Francois Arago, and Augus......The idea of measuring stellar aberration with a water-filled telescope was entertained from the middle of the 18th century by Thomas Melvill, Patrick Wilson, Roger Joseph Boscovich, and John Robison. I shall discuss their ideas as well as those discussed by Thomas Young, Francois Arago......, and Augustin Fresnel in the beginning of the 19th century. None of these scientists actually performed this experiments. All except Boscovich came to realize that water-filled telescopes would lead to the same stellar aberration as an ordinary telescope. For Fresnel, moreover, it led to a precise value...

  17. 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 ...

  18. The calculation of electromagnetic fields in the Fresnel and Fraunhofer regions using numerical integration methods

    Science.gov (United States)

    Schmidt, R. F.

    1971-01-01

    Some results obtained with a digital computer program written at Goddard Space Flight Center to obtain electromagnetic fields scattered by perfectly reflecting surfaces are presented. For purposes of illustration a paraboloidal reflector was illuminated at radio frequencies in the simulation for both receiving and transmitting modes of operation. Fields were computed in the Fresnel and Fraunhofer regions. A dual-reflector system (Cassegrain) was also simulated for the transmitting case, and fields were computed in the Fraunhofer region. Appended results include derivations which show that the vector Kirchhoff-Kottler formulation has an equivalent form requiring only incident magnetic fields as a driving function. Satisfaction of the radiation conditions at infinity by the equivalent form is demonstrated by a conversion from Cartesian to spherical vector operators. A subsequent development presents the formulation by which Fresnel or Fraunhofer patterns are obtainable for dual-reflector systems. A discussion of the time-average Poynting vector is also appended.

  19. 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.

  20. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chemisana, D., E-mail: daniel.chemisana@macs.udl.cat [University of Lleida, c/Pere Cabrera s/n, 25001 Lleida (Spain); Ibanez, M.; Rosell, J.I. [University of Lleida, c/Pere Cabrera s/n, 25001 Lleida (Spain)

    2011-09-15

    Highlights: {yields} A combined domed Fresnel lens - CPC PVT system is designed and characterized. {yields} Electrical and thermal experiments have been performed. {yields} 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.

  2. 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...... 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....

  3. Biaxial-Type Concentrated Solar Tracking System with a Fresnel Lens for Solar-Thermal Applications

    OpenAIRE

    Tsung Chieh Cheng; Chao Kai Yang; I Lin

    2016-01-01

    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 main...

  4. 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.

  5. Optical Tests on a Curve Fresnel Lens as Secondary Optics for Solar Troughs

    Directory of Open Access Journals (Sweden)

    D. Fontani

    2017-01-01

    Full Text Available A curve Fresnel lens is developed as secondary concentrator for solar parabolic troughs to reduce the number of photovoltaic cells. Specific measurements and optical tests are used to evaluate the optical features of manufactured samples. The cylindrical Fresnel lens transforms the focal line, produced by the primary mirror, into a series of focal points. The execution of special laboratory tests on some secondary concentrator samples is discussed in detail, illustrating the methodologies tailored to the specific case. Focusing tests are performed, illuminating different areas of the lens with solar divergence light and acquiring images on the plane of the photocell using a CMOS camera. Concentration measurements are carried out to select the best performing samples of curve Fresnel lens. The insertion of the secondary optics within the concentrating photovoltaic (CPV trough doubles the solar concentration of the system. The mean concentration ratio is 1.73, 2.13, and 2.09 for the three tested lenses. The concentration ratio of the solar trough is 140 and approaches 300 after the introduction of the secondary lens.

  6. Field characterization of steady state focused transducers using hydrophones based on Fresnel approximation

    Science.gov (United States)

    Xing, Guangzhen; Yang, Ping; Hu, Pengcheng; Lam, Kwok Ho; He, Longbiao; Zhang, Zhonghua

    2017-06-01

    This paper is intended to estimate the spatial averaging effects of the hydrophone in field characterization of focused transducers. The analytical model derived was based on Fresnel approximation and enabled modifications of the results for both on-axis and off-axis measurement arrangements. The axial and lateral field distributions in the focal plane measured by the hydrophone were derived for both non-attenuating and attenuating fluids in the model. The spatial averaging effects result in underestimating the absolute acoustic pressure amplitudes, and overestimating the cross-sectional size of the beam directivity pattern in the focal plane. The validity of the Rayleigh integral and the Fresnel approximation for curved transducers were discussed. The results indicate that, for \\sqrt{k\\frac{≤ft({{a}\\text{h}}+b\\right)}{2}}\\gg π (where k is the circular wave number, a h is the chord from the center of curved surface to the boundary and b is the effective radius of the hydrophone), the Fresnel approximation remains valid for all locations of the hydrophone in the focused field. Particularly, in the focal plane, the spatial averaging effects of the hydrophone on the directivity pattern of the acoustic beam can be neglected for k\\frac{{{b}2}+4ab}{2{{l}\\text{f}}}\\ll 1 (where a and l f are the effective radius and focal distance of the focused transducer).

  7. WIMP dark matter in a well-tempered regime — A case study on singlet-doublets fermionic WIMP

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Shankha [LAPTH, University de Savoie, CNRS,B.P.110, F-74941 Annecy-le-Vieux (France); Matsumoto, Shigeki; Mukaida, Kyohei; Tsai, Yue-Lin Sming [Kavli IPMU (WPI), UTIAS, University of Tokyo,Kashiwa, 277-8583 (Japan)

    2016-11-10

    Serious searches for the weakly interacting massive particle (WIMP) have now begun. In this context, the most important questions that need to be addressed are: To what extent can we constrain the WIMP models in the future? and What will then be the remaining unexplored regions in the WIMP parameter space for each of these models? In our quest to answer these questions, we classify WIMP in terms of quantum number and study each case adopting minimality as a guiding principle. As a first step, we study one of the simple cases of the minimal composition in the well-tempered fermionic WIMP regime, namely the singlet-doublets WIMP model. We consider all available constraints from direct and indirect searches and also the predicted constraints coming from the near future and the future experiments. We thus obtain the current status, the near future prospects and the future prospects of this model in all its generality. We find that in the future, this model will be constrained almost solely by the future direct dark matter detection experiments (as compared to the weaker indirect and collider constraints) and the cosmological (relic density) constraints and will hence be gradually pushed to the corner of the coannihilation region, if no WIMP signal is detected. Future lepton colliders will then be useful in exploring this region not constrained by any other experiments.

  8. 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.

  9. Can Old Regimes Handle New Wars?

    DEFF Research Database (Denmark)

    Henningsen, Troels

    strengthen Islamist insurgents. Using a comparative case study of the regimes in Chad and Mali from 2003 to 2016 and applying a theoretical framework of regime survival in states with internal anarchy, this paper explains how regimes in the Sahel region defend themselves against insurgents. Surprisingly...

  10. Molecular dynamics studies of electron-ion temperature equilibration in hydrogen plasmas within the coupled-mode regime.

    Science.gov (United States)

    Benedict, Lorin X; Surh, Michael P; Stanton, Liam G; Scullard, Christian R; Correa, Alfredo A; Castor, John I; Graziani, Frank R; Collins, Lee A; Čertík, Ondřej; Kress, Joel D; Murillo, Michael S

    2017-04-01

    We use classical molecular dynamics (MD) to study electron-ion temperature equilibration in two-component plasmas in regimes for which the presence of coupled collective modes has been predicted to substantively reduce the equilibration rate. Guided by previous kinetic theory work, we examine hydrogen plasmas at a density of n=10^{26}cm^{-3}, T_{i}=10^{5}K, and 10^{7}K

  11. Experimental study on effect of channel size on upward air-water two-phase flow regimes in vertical channels

    International Nuclear Information System (INIS)

    Yan Chaoxing; Yan Changqi; Sun Licheng; Wang Yang

    2012-01-01

    A visualized study of flow patterns was carried out for air-water two-phase flow in two narrow rectangular ducts (40 mm × l.41 mm, 40 mm × 10 mm) and a circular tube with a diameter of 25 mm, respectively. The superficial velocity air and water were in the range of 0.03-24.71 m/s and 0.03-3.73 m/s. All the bubble, slug, churn and annular flows occurred in the three channels. Characteristics of flow patterns in the 40 mm × 10 mm duct are very similar to those in circular tube, but different from the 40 mm × l.41 mm duct. Detailed flow regime maps of the three channels were presented. The experimental results show that the channel size has a significant influence on flow pattern transition, boundary of which in rectangular channels tends asymptotically towards that in the circular tube with increasing the width of narrow side. (authors)

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. The US and India Security-Economic Dilemma: A Study on the Effects of Relative Gain Sensitivities and Regime Formation

    Science.gov (United States)

    2014-05-01

    New York: Norton, 2001), 55. 5 Robert Gilpin , War and Change in World Politics, (Cambridge; New York: Cambridge University Press, 1981), 40. 6 For... Robert Gilpin as system, systemic, and interaction that occur within those areas.18 The types of change provide common ground for both theories to rest...significantly influences the development and sustainment of a regime. 18 Robert Gilpin , War and

  18. 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.

  19. 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

  20. 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).

  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

    The evaluation of an adequate and robust measuring strategy, for roughness assessment of polymer Fresnel lenses is put under assessment. An ‘on-sample’ measurement noise, is evaluated using a laser confocal microscope (OLYMPUS © Lext). Secondly, the lowest-noise roughness measuring procedure...... is performed by comparing ‘on-sample’ noise with the one calculated on an optical flat. Noise is investigated by means of established methods, i.e. subtraction and averaging methods. Afterwards, the lowest-noise analysis is structured following a 23 full factorial experimental planning, whose factors...

  2. 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.)

  3. 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.

  4. 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...

  5. Evaluation and comparison of different designs and materials for Fresnel lens-based solar concentrators

    Science.gov (United States)

    Fu, Ling; Leutz, Ralf; Annen, Hans Philipp

    2011-10-01

    Optics with high optical efficiency and reliability are the key components for CPV modules as well as high efficiency solar cells and a high accuracy tracker. The present paper describes the optical design, simulation and materials, including a direct comparison of geometrically identical lens designs for different materials i. e. PMMA (or acrilic) and silicone-on-glass (SOG) respectively, and glass secondary in three different geometries. The Fresnel lenses manufactured as 5×4 monolithic parquets are called Triple Primaries, and serve as test samples and off-the-shelf products of Concentrator Optics GmbH.

  6. 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

  7. 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.

  8. Small Business Tax Regimes

    OpenAIRE

    Yilmaz, Fatih; Coolidge, Jacqueline

    2016-01-01

    Simplified tax regimes for micro and small enterprises in developing countries are intended to facilitate voluntary tax compliance. However, survey evidence suggests that small business taxation based on simplified bookkeeping or turnover is sometimes perceived as too complex for microenterprises in countries with high illiteracy levels. Very simple fixed tax regimes not requiring any book...

  9. 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 ...

  10. 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)

  11. 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.

  12. 3D printing optical watermark algorithms based on the combination of DWT and Fresnel transformation

    Science.gov (United States)

    Hu, Qi; Duan, Jin; Zhai, Di; Wang, LiNing

    2016-10-01

    With the continuous development of industrialization, 3D printing technology steps into individuals' lives gradually, however, the consequential security issue has become the urgent problem which is imminent. This paper proposes the 3D printing optical watermark algorithms based on the combination of DWT and Fresnel transformation and utilizes authorized key to restrict 3D model printing's permissions. Firstly, algorithms put 3D model into affine transform, and take the distance from the center of gravity to the vertex of 3D object in order to generate a one-dimensional discrete signal; then make this signal into wavelet transform and put the transformed coefficient into Fresnel transformation. Use math model to embed watermark information into it and finally generate 3D digital model with watermarking. This paper adopts VC++.NET and DIRECTX 9.0 SDK for combined developing and testing, and the results show that in fixed affine space, achieve the robustness in translation, revolving and proportion transforms of 3D model and better watermark-invisibility. The security and authorization of 3D model have been protected effectively.

  13. 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

  14. 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)

  15. 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)

  16. 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.

  17. 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.

  18. Friction regimes in the lubricants solid-state regime

    NARCIS (Netherlands)

    Schipper, Dirk J.; Maathuis, O.; Dowson, D.; Taylor, C.M.; Childs, T.H.C.; Dalmaz, G.

    1995-01-01

    Friction measurements were performed in the lubricant's solid-state regime to study the transition from full-film lubrication, in which the separation is maintained by a solidified lubricant, to mixed lubrication. Special attention is paid to the influence of temperature (inlet viscosity) and

  19. The efficacy of iron chelator regimes in reducing cardiac and hepatic iron in patients with thalassaemia major: a clinical observational study

    Directory of Open Access Journals (Sweden)

    Berdoussi Eleni

    2009-06-01

    Full Text Available Abstract Background Available iron chelation regimes in thalassaemia may achieve different changes in cardiac and hepatic iron as assessed by MR. The aim of this study was to assess the efficacy of four available iron chelator regimes in 232 thalassaemia major patients by assessing the rate of change in repeated measurements of cardiac and hepatic MR. Results For the heart, deferiprone and the combination of deferiprone and deferoxamine significantly reduced cardiac iron at all levels of iron loading. As patients were on deferasirox for a shorter time, a second analysis ("Initial interval analysis" assessing the change between the first two recorded MR results for both cardiac and hepatic iron (minimum interval 12 months was made. Combination therapy achieved the most rapid fall in cardiac iron load at all levels and deferiprone alone was significantly effective with moderate and mild iron load. In the liver, deferasirox effected significant falls in iron load and combination therapy resulted in the most rapid decline. Conclusion With the knowledge of the efficacy of the different available regimes and the specific iron load in the heart and the liver, appropriate tailoring of chelation therapy should allow clearance of iron. Combination therapy is best in reducing both cardiac and hepatic iron, while monotherapy with deferiprone or deferasirox are effective in the heart and liver respectively. The outcomes of this study may be useful to physicians as to the chelation they should prescribe according to the levels of iron load found in the heart and liver by MR.

  20. 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)

  1. 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

  2. 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.

  3. 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 ...

  4. 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

  5. Internal structure of an intact Convallaria majalis pollen grain observed with X-ray Fresnel coherent diffractive imaging

    NARCIS (Netherlands)

    Mancuso, Adrian P; Groves, Matthew R; Polozhentsev, Oleg E; Williams, Garth J; McNulty, Ian; Antony, Claude; Santarella-Mellwig, Rachel; Soldatov, Aleksander V; Lamzin, Victor; Peele, Andrew G; Nugent, Keith A; Vartanyants, Ivan A

    2012-01-01

    We have applied Fresnel Coherent Diffractive Imaging (FCDI) to image an intact pollen grain from Convallaria majalis. This approach allows us to resolve internal structures without the requirement to chemically treat or slice the sample into thin sections. Coherent X-ray diffraction data from this

  6. 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.

  7. 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

    BACKGROUND: Laparoscopic cholecystectomy is now often an ambulatory procedure, but dependent on short-term post-operative complaints of pain and post-operative nausea and vomiting (PONV). The efficacy of post-anaesthesia care units (PACUs) is therefore important to facilitate return to normal...... 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...... to discharge (mean, 88 min). There were on average 2.7 treatment interventions (range, 0-11) before discharge. CONCLUSION: An evidence-based, multimodal approach to the anaesthetic/analgesic management in laparoscopic cholecystectomy is feasible and advantageous in the early post-operative phase. Pain and PONV...

  8. 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 Michael

    2007-01-01

    to discharge (mean, 88 min). There were on average 2.7 treatment interventions (range, 0-11) before discharge. CONCLUSION: An evidence-based, multimodal approach to the anaesthetic/analgesic management in laparoscopic cholecystectomy is feasible and advantageous in the early post-operative phase. Pain and PONV......BACKGROUND: Laparoscopic cholecystectomy is now often an ambulatory procedure, but dependent on short-term post-operative complaints of pain and post-operative nausea and vomiting (PONV). The efficacy of post-anaesthesia care units (PACUs) is therefore important to facilitate return to normal...... 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...

  9. 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

  10. 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.

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

    Science.gov (United States)

    Abdel-Hadi, Yasser A.; Ghitas, A.; Abulwfa, A.; Sabry, M.

    2015-12-01

    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.

  12. 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.

  13. 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)

  14. 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.

  15. X-ray Fourier transform holography by amplitude-division-type Fresnel zone plate interferometer.

    Science.gov (United States)

    Balyan, Minas; Haroutunyan, Levon

    2018-01-01

    A two-block X-ray Fresnel zone plate system forms two-beams - a plane wave and a spherical wave - which interfere at the focal distance of the virtual source of the spherical wave. An object placed in the path of the plane wave forms an object wave and the spherical wave is the reference wave. The recorded intensity distribution is the Fourier transform hologram of the object. Analytical and numerical calculations show the possibilities of this scheme to record the hologram and reconstruct the object image. Examples of recording holograms of a one-dimensional cosine-like grating and a two-dimensional grid object as well as reconstruction of the images are considered.

  16. Towards Realization of an Atomic deBroglie Microscope: Helium Atom Focusing Using Fresnel Zone Plates

    Science.gov (United States)

    Doak, R. B.; Grisenti, R. I.; Rehbein, S.; Schmahl, G.; Toennies, J. P.; Wöll, Ch.

    1999-10-01

    Virtually all focusing microscopes currently employ either photons or electrons as the imaging medium, largely due to the ease with which these two species can be focused. On the basis of other factors - resolution, contrast, and sample damage - a helium atom would often be preferred, particularly in the microscopy of solid surfaces. The focusing of a neutral atom beam has proven difficult, however. This work reports the successful focusing of a neutral, ground state, ^4He atom beam using custom, state-of-the-art Fresnel zone plates. Glass microskimmers of aperture as small as 1 micron diameter were used to define the incident beam. At only moderate demagnification (x 0.40), a focused spot diameter of Raster scans across 15 and 25 micron wide slits have been recorded, demonstrating transmission scanning helium deBroglie microscopy at this near-micron resolution.

  17. Fresnel zone plate with apodized aperture for hard X-ray Gaussian beam optics.

    Science.gov (United States)

    Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio; Itabashi, Seiichi; Oda, Masatoshi

    2017-05-01

    Fresnel zone plates with apodized apertures [apodization FZPs (A-FZPs)] have been developed to realise Gaussian beam optics in the hard X-ray region. The designed zone depth of A-FZPs gradually decreases from the center to peripheral regions. Such a zone structure forms a Gaussian-like smooth-shouldered aperture function which optically behaves as an apodization filter and produces a Gaussian-like focusing spot profile. Optical properties of two types of A-FZP, i.e. a circular type and a one-dimensional type, have been evaluated by using a microbeam knife-edge scan test, and have been carefully compared with those of normal FZP optics. Advantages of using A-FZPs are introduced.

  18. 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.

  19. 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.

  20. 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.

  1. Estimation of objects transverse parameters in off-axis and in-line Fresnel digital holography

    Science.gov (United States)

    Cheremkhin, Pavel A.; Evtikhiev, Nikolay N.; Krasnov, Vitaly V.; Rodin, Vladislav G.; Starikov, Sergey N.

    2015-05-01

    In this report transverse parameters of objects registered with inline and off-axis Fresnel digital holography schemes were estimated: maximum transverse dimensions of objects, size and quantity of object resolution elements. By determining allowed locations of diffraction orders under reconstruction, new expressions for estimation of objects transverse parameters were obtained. In case of off-axis holography it is desirable that object should not overlap with zero-order and twin images. If object and twin images are located on opposite sides relative to zero-order under reconstruction, this is case of preventing of cyclic shift of twin image (PCS). If twin image is located on both sides relative to zero-order under reconstruction but don't overlap with object image, this is case of assumption of cyclic shift of twin image (ACS). ACS case allows to register digital holograms of larger objects compared to PCS case. However, for example, for automatic image processing, separate display of object and twin images relative to zero-order is often required. It was found that ACS case allows to register holograms with distance between the object and hologram 1.5 times lesser than in PCS case. And maximum transverse dimension of object in ACS case is always greater than in PCS case by the half of hologram size. For verification of obtained estimates, off-axis digital Fresnel holograms with 2048x2048 pixels were optically registered. Contour images located behind static scatter were used as objects. Confirmations on transverse object parameters estimates, satisfying ACS and PCS cases, were derived. These results demonstrate correctness of obtained quantitative estimates.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Friction regimes in the lubricants solid-state regime

    OpenAIRE

    Schipper, Dirk J.; Maathuis, O.; Dowson, D.; Taylor, C.M.; Childs, T.H.C.; Dalmaz, G.

    1995-01-01

    Friction measurements were performed in the lubricant's solid-state regime to study the transition from full-film lubrication, in which the separation is maintained by a solidified lubricant, to mixed lubrication. Special attention is paid to the influence of temperature (inlet viscosity) and roughness on this transition. The friction measurements showed that in the lubricants solid-state region three lubrication modes can be distinguished: A) full-film lubrication; separation is maintained b...

  11. 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

  12. 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...

  13. Understanding regime shifts

    DEFF Research Database (Denmark)

    Heymann, Matthias; Nielsen, Kristian Hvidtfelt

    ”. Danish wind power development is all the more surprising, as the innovation process in wind technology was carried to a large extent by non-academic craftsmen and political activists. Many features of this innovation story have been investigated and that research makes it possible to summarize...... the current understanding of the regime shift....

  14. 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 extrem...

  15. 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.

  16. 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.

  17. Design and development of a high-concentration and high-efficiency photovoltaic concentrator using a curved Fresnel lens

    Energy Technology Data Exchange (ETDEWEB)

    Scharlack, R.S.; Moffat, A.

    1983-08-01

    Thermo Electron has designed a high concentration photovoltaic module that uses a domed, point-focus Fresnel lens. Their design, design optimization process, and results from lens and receiver tests are described in this report. A complete module has not been fabricated and probably will not be fabricated in the future; however, Thermo Electron's optical design, analysis, and testing of both secondary optical units and domed Fresnel lenses have made a significant contribution to our project. Tooling errors prevented the lens from reaching its potential efficiency by the end of the contract, and resolution of these tooling problems is currently being attempted with a follow-on contract, No. 68-9463.

  18. In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement

    Directory of Open Access Journals (Sweden)

    Umesh Sampath

    2015-07-01

    Full Text Available A fiber-optic cure monitoring system is proposed to measure curing status of composite structure such as a large scale wind turbine blade. The monitoring is based on the measurement of Fresnel reflectivity at the optical fiber/epoxy resin interface. The refractive index of epoxy resin varies throughout curing stages, changing the Fresnel reflectivity. The curing status is decided by monitoring the reflected intensity variation. The usage of fiber Bragg grating (FBG sensor helps to separate the temperature-induced cross effects. A Gaussian curve fitting algorithm was applied to FBG spectra which were distorted in curing procedure. The substantial measurement errors could be minimized by locating the centroids of the Gaussian curve-fitted spectra. From the experiments performed in various isothermal conditions, the proposed system successfully identified the onset of gelation and the completion of curing of epoxy resins.

  19. A geometric approach to strong coupling effects in heavy-ion collisions. Deviation from the Fresnel diffraction pattern

    Science.gov (United States)

    Takigawa, N.; Michel, F.; Balantekin, A. B.; Reidemeister, G.

    1991-06-01

    We offer a novel interpretation of the deviation of the experimental angular distribution for elastic 18O+ 184W scattering at 90 MeV from the standard Fresnel diffraction pattern in terms of an interference between scattering amplitudes corresponding to different orientations of the target nucleus. The importance of Coriolis coupling, which is initially neglected in this geometric approach, is discussed in the case where long-range Coulomb coupling is active.

  20. A geometric approach to strong coupling effects in heavy-ion collision. Deviation from the Fresnel diffraction pattern

    Energy Technology Data Exchange (ETDEWEB)

    Takigawa, N. (Tohoku Univ., Sendai (Japan). Dept. of Physics); Michel, F. (Mons Univ. (Belgium). Faculte des Sciences); Balantekin, A.B. (Wisconsin Univ., Madison (USA). Dept. of Physics); Reidemeister, G. (Universite Libre de Bruxelles (Belgium). Faculte des Sciences)

    1991-06-20

    We offer a novel interpretation of the deviation of the experimental angular distribution for elastic {sup 18}O+{sup 184}W scattering at 90 MeV from the standard Fresnel diffraction pattern in terms of an interference between scattering amplitudes corresponding to different orientations of the target nucleus. The importance of Coriolis coupling, which is initially neglected in this geometric approach, is discussed in the case where long-range Coulomb coupling is active. (orig.).

  1. MODELING COMBINING TAX REGIMES

    Directory of Open Access Journals (Sweden)

    Prishchenko E. A.

    2016-03-01

    Full Text Available The article discusses the combination of tax regimes as a result of separation from the operating business of the revenues and costs for system of a united tax on imputed income (UTII with the analysis of the tax consequences of such allocation. Three models of taxation were built: both variants of the simplified system of taxation from UTII and common system of taxation with UTII. We propose a rapid method of the most preferred system of taxation for small businesses’ selection depending material to labor costs ratio. All these results could be implemented in the case when the company starts a new type of activity under the rules UTII, and solves the problem in the framework of the tax regime to conduct this activity - UTII applied or not, based on the criterion of tax savings. Using the relations describing the tax burden when combined tax regimes, we can determine what the yield should have a new business line and what cost structure should it have to reduce the tax burden. The main result is proposed approach that can be used as a tool of tax planning activities of small businesses.

  2. Distinct solubility and cytotoxicity regimes of paclitaxel-loaded cationic liposomes at low and high drug content revealed by kinetic phase behavior and cancer cell viability studies.

    Science.gov (United States)

    Steffes, Victoria M; Murali, Meena M; Park, Yoonsang; Fletcher, Bretton J; Ewert, Kai K; Safinya, Cyrus R

    2017-11-01

    Lipid-based particles are used worldwide in clinical trials as carriers of hydrophobic paclitaxel (PTXL) for cancer chemotherapy, albeit with little improvement over the standard-of-care. Improving efficacy requires an understanding of intramembrane interactions between PTXL and lipids to enhance PTXL solubilization and suppress PTXL phase separation into crystals. We studied the solubility of PTXL in cationic liposomes (CLs) composed of positively charged 2,3-dioleyloxypropyltrimethylammonium chloride (DOTAP) and neutral 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) as a function of PTXL membrane content and its relation to efficacy. Time-dependent kinetic phase diagrams were generated from observations of PTXL crystal formation by differential-interference-contrast microscopy. Furthermore, a new synchrotron small-angle x-ray scattering in situ methodology applied to DOTAP/DOPC/PTXL membranes condensed with DNA enabled us to detect the incorporation and time-dependent depletion of PTXL from membranes by measurements of variations in the membrane interlayer and DNA interaxial spacings. Our results revealed three regimes with distinct time scales for PTXL membrane solubility: hours for >3 mol% PTXL (low), days for ≈ 3 mol% PTXL (moderate), and ≥20 days for Cell viability experiments on human cancer cell lines using CL PTXL nanoparticles (NPs) in the distinct CL PTXL solubility regimes reveal an unexpected dependence of efficacy on PTXL content in NPs. Remarkably, formulations with lower PTXL content and thus higher stability show higher efficacy than those formulated at the membrane solubility limit of ≈3 mol% PTXL (which has been the focus of most previous physicochemical studies and clinical trials of PTXL-loaded CLs). Furthermore, an additional high-efficacy regime is seen on occasion for liposome compositions with PTXL ≥9 mol% applied to cells at short time scales (hours) after formation. At longer time scales (days), CL PTXL NPs with ≥3

  3. An optical switch of natural light guiding system based on cubic structure with fresnel surface

    Science.gov (United States)

    Chou, Kao-Hsu; Chen, Yi-Yung; Whang, Allen Jong-Woei

    2009-08-01

    Recently, many researches focus on illumination with sunlight for saving energy and healthy lighting. A Natural Light Guiding System has collecting, transmitting, and lighting parts. In most systems, the paths on transmitting part are fixed so the collected sunlight of the Natural Light Guiding System can not be free managed and is sometime wasted. In this paper, we design an optical switch to change the path of the collected sunlight on the transmitting sunlight. The switch is cubic structure that includes a 45 degree mirror for reflecting sunlight. According to the structure of the optical switch, we can rotate the switch to manage the path of the collected sunlight. When the path is parallel with the mirror, the sunlight will pass through the switch; and when the included angle between the path and mirror is 45 degree, we can change the path of light. For coupling the exit beam into lightpipe, we design the surfaces of cubic structure to be aspheric surface with Fresnel surface. Finally, we simulate the efficiency of the optical switch when the path is changed by the mirror.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. A simplified fabrication process of Fresnel zone plates with controlling proximity effect correction.

    Science.gov (United States)

    Jeon, Sang Chul; Kim, Deuk Su; Kim, Ki Nam; Kim, Kyung Min; Seo, Chang Ho; Yoo, Jung Jae; Lee, Dong Kyu

    2011-01-01

    Fresnel zone plates (FZPs) for soft X-ray microscopy with an energy range of 284 eV to 540 eV are designed and fabricated in a simple method. An adequate aspect ratio of the resist mold for electroplating was obtained by the proximity effect correction technology for an incident electron beam on a single thick layer resist. Without additional complicated reactive ion etching, a sufficient electro plating mold for nickel structures was fabricated. The overall fabrication procedures which involve a mix-and-match overlay technique for electron beam lithography and an optic exposure system that centers the membrane on the nanostructures, and hybrid silicon etching technology in junction with deep anisotropy and a KOH wet method in order to release the backside Si substrates of the Si3N4 membranes with no deformation of FZPs are introduced. High quality nanostructures with minimum outermost zone widths of 50 nm and diameters of 120 microm were fabricated with simplified fabrication process and with cost-effective.

  9. Focusing Bistatic FMCW SAR Signal by Range Migration Algorithm Based on Fresnel Approximation

    Directory of Open Access Journals (Sweden)

    Yake Li

    2015-12-01

    Full Text Available Frequency modulated continuous wave (FMCW technique has recently been employed by synthetic aperture radar (SAR to decrease the radar cost and volume. However, the operation range is limited by the direct energy leakage from the transmitting channel to receiving channel due to the operation principle of FMCW technique. Bistatic configuration is an efficient way to increase the isolation between the transmitter and receiver, which could significantly increase the radar standoff range. A bistatic FMCW SAR spectrum model is proposed by using the Fresnel approximation in this paper. This model is similar to that of a monostatic FMCW SAR spectrum, which allows the existing imaging algorithms to be used on bistatic image processing. Based on the new model and the characteristics of FMCW signal, a modified range migration algorithm (RMA for FMCW SAR is proposed to focus the image, which requires less memory and computational load than the traditional RMA. Point-target simulation is used to verify the proposed spectral model and real data processing verified the effectiveness of the proposed RMA.

  10. 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.

  11. 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. 

  12. 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

  13. An experimental study of the regimes of motion of spheres falling or ascending freely in a Newtonian fluid

    NARCIS (Netherlands)

    Veldhuis, Christian; Veldhuis, C.H.J.; Biesheuvel, A.

    2007-01-01

    This paper presents the results of an experimental investigation aimed at verifying some of the interesting conclusions of the numerical study by Jenny et al. concerning the instability and the transition of the motion of solid spheres falling or ascending freely in a Newtonian fluid. The phenomenon

  14. Numerical and experimental studies of the NO formation in laminar coflow diffusion flames on their transition to MILD combustion regime

    NARCIS (Netherlands)

    Sepman, A. V.; Abtahizadeh, S. E.; Mokhov, A. V.; van Oijen, J. A.; Levinsky, H. B.; de Goey, L. P. H.

    An experimental and numerical study of NO formation in diluted and preheated combustion has been carried out to provide more insight into the ultimate low-NOx potential of MILD combustion. The measured profiles of NO mole fraction were obtained using laser-induced fluorescence (LIF) in the three

  15. 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

  16. Study on the valorization routes of ashes from thermoelectric power plants working under mono-and co-combustion regimes

    Science.gov (United States)

    Barbosa, Rui Pedro Fernandes

    The main objective of this thesis was to study new valorization routes of ashes produced in combustion and co-combustion processes. Three main valorization pathways were analyzed: (i)production of cement mortars, (ii) production of concretes, and (iii) use as chemical agents to remove contaminants from wastewaters. Firstly, the ashes produced during the mono-combustion of coal, co-combustion of coal and meat and bone meal (MBM), and mono-combustion of MBM were characterized. The aim of this study was to understand the ashes properties in extreme levels of substitution of coal by a residue with a high contamination of specific metals. The substitution of coal by MBM produced ashes with higher content of heavy metals. Secondly, the ashes coming from an industrial power plant working under mono-combustion(coal) and co-combustion conditions (coal+sewage sludge+MBM) were studied. The use of cofuels did not promote significant changes in the chemical and ecotoxicological properties of ashes. Fly ashes were successfully stabilized/solidified in cement mortar, and bottom and circulating ashes were successfully used as raw materials in concrete. The third step involved the characterization and valorization of biomass ashes resulting from the combustion of forestry residues. The highest concentrations of metals/metalloids were found in the lowest particle size fractions of ashes. Biomass ashes successfully substituted cement and natural aggregates in concretes, without compromising their mechanical, chemical, and ecotoxicological properties. Finally, the biomass ashes were tested as chemical agents to remove contaminants from wastewaters. The removal of P, mainly phosphates, and Pb from wastewaters was assayed. Biomass ashes presented a high capacity to remove phosphates. As fly ashes were more efficient in removing phosphates, they were further used to remove Pb from wastewaters. Again, they presented a high efficiency in Pb removal. New potential valorization routes for

  17. The Two Regimes of Postwar Shipping

    DEFF Research Database (Denmark)

    Iversen, Martin Jes; Tenold, Stig

    2014-01-01

    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...... 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....

  18. Policy Regime Juxtaposition in Latin America

    Directory of Open Access Journals (Sweden)

    Kent Eaton

    2017-04-01

    Full Text Available This article has three main objectives, each in the spirit of broadening the study of subnational politics to include the juxtaposition of policy regimes and not just political regimes. First, it identifies the causes that help explain why we are seeing more territorial heterogeneity within countries in terms of the pursuit of ideologically disparate development models at different levels of government. Second, the article assesses the importance of this trend by analyzing the chief advantages and disadvantages of policy regime juxtaposition. Third, I turn to the question of why subnational officials are able to defend ideologically deviant policy regimes in some cases, but not in others. Based on the Bolivian, Ecuadorian, and Peruvian cases, my argument emphasizes the importance of two key factors: capacity and coalitions.

  19. 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.

  20. 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

  1. Future hydrological regimes and glacier cover in the Everest region: The case study of the upper Dudh Koshi basin.

    Science.gov (United States)

    Soncini, Andrea; Bocchiola, Daniele; Confortola, Gabriele; Minora, Umberto; Vuillermoz, Elisa; Salerno, Franco; Viviano, Gaetano; Shrestha, Dibas; Senese, Antonella; Smiraglia, Claudio; Diolaiuti, Guglielmina

    2016-09-15

    Assessment of future water resources under climate change is required in the Himalayas, where hydrological cycle is poorly studied and little understood. This study focuses on the upper Dudh Koshi river of Nepal (151km(2), 4200-8848ma.s.l.) at the toe of Mt. Everest, nesting the debris covered Khumbu, and Khangri Nup glaciers (62km(2)). New data gathered during three years of field campaigns (2012-2014) were used to set up a glacio-hydrological model describing stream flows, snow and ice melt, ice cover thickness and glaciers' flow dynamics. The model was validated, and used to assess changes of the hydrological cycle until 2100. Climate projections are used from three Global Climate Models used in the recent IPCC AR5 under RCP2.6, RCP4.5 and RCP8.5. Flow statistics are estimated for two reference decades 2045-2054, and 2090-2099, and compared against control run CR, 2012-2014. During CR we found a contribution of ice melt to stream flows of 55% yearly, with snow melt contributing for 19%. Future flows are predicted to increase in monsoon season, but to decrease yearly (-4% vs CR on average) at 2045-2054. At the end of century large reduction would occur in all seasons, i.e. -26% vs CR on average at 2090-2099. At half century yearly contribution of ice melt would be on average 45%, and snow melt 28%. At the end of century ice melt would be 31%, and snow contribution 39%. Glaciers in the area are projected to thin largely up to 6500ma.s.l. until 2100, reducing their volume by -50% or more, and their ice covered area by -30% or more. According to our results, in the future water resources in the upper Dudh Koshi would decrease, and depend largely upon snow melt and rainfall, so that adaptation measures to modified water availability will be required. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. 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)

  3. 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.

  4. 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

  5. Establishing quantitative relations between mammalian communities, climate regimes, and vegetation density - A diversity-based reference model and case study

    Science.gov (United States)

    Hertler, Christine; Wolf, Dominik; Bruch, Angela; Märker, Michael

    2013-04-01

    Pleistocene specialized herbivore communities permits to infer habitat features. The hominin locality Makuyuni permits to study two successive fossil communities and changes occurring. Both fossil horizons are associated with either hominin specimens and/or artifacts. Therefore, hominins persist in the habitats in view of a changing environment.

  6. The initial regime of drop coalescence

    Science.gov (United States)

    Anthony, Christopher; Harris, Michael; Basaran, Osman

    2017-11-01

    Drop coalescence plays a key role in both industry and nature. Consequently, study of the phenomenon has been the focus of numerous experimental, computational and theoretical works to date. In coalescence, two drops come into contact and a liquid bridge forms between them. As time advances, this bridge grows from microscopic to macroscopic scales. Despite the large volume of work dedicated to this problem, currently experiment, theory, and computation are not in perfect agreement with respect to the earliest times following the initial contact of the drops. Experiments report an initial regime where the radius of the connecting bridge grows linearly in time before a transition to either a Stokes regime or an inertial regime where either viscous or inertial forces balance capillary force. In the initial linear regime, referred to as the inertially-limited viscous regime, all three forces are thought to be important. This is in contrast to theory which predicts that all coalescence events begin in the Stokes regime. We use high accuracy numerical simulation to show that the existing discrepancy in the literature can be resolved by paying careful attention to the initial conditions that set the shape and size of the bridge connecting the two drops.

  7. 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.

  8. A study of source parameters and attenuation of earthquakes in a regime of subduction in the east of Venezuela using Genetic Algorithms

    Science.gov (United States)

    Granado, C.; Vasquez, R.

    2007-05-01

    A sample of 50 earthquakes associated with the regime of subduction in the east of Venezuela has been analyzed in order to determine the following source parameters: seismic moment, stress drop and attenuation Q. The spectral content of the seismograms of this sample was studied with Brune´s model as a basic reference, while the numerical treatment- by means of Genetic Algorithms. The studied seismograms were obtained through the network of the Venezuelan Seismological Foundation, with FUNVISIS broadband sensors detecting noise signals for calculating Q. The spectral analysis of seismograms of this sample reveals preliminary values for M0 between 6.E+9 to 8.5E+12 Nm. When considering attenuation Q for frequencies of 2, 5, 4, 8 and 10 Hertz, a variable Q was obtained from 125 to 590, indicating a different tectonic behavior compared to a sample of superficial seismicity of greater attenuation for the same geographic region. Additionally, the correlation between Q(P) and Q(S) for the earthquakes of the relevant region was investigated.

  9. Study of the interaction between a fluid and an oscillating structure: forces and flow regimes, from an isolated cylinder to a bundle of cylinders

    International Nuclear Information System (INIS)

    Duclercq, M.

    2010-01-01

    This thesis presents a 2D numerical and physical study of the dynamics of a viscous incompressible fluid initially at rest, put in motion by forced transverse rectilinear oscillations of a cylinder. That system is described by two dimensionless numbers. The Reynolds number (Re) measures the ratio of the inertial forces to the viscous forces, and the Keulegan-Carpenter number (KC) compares the amplitude of the cylinder oscillations to its diameter. The objective is to determine the influence of those two parameters on the drag and transverse forces exerted by the fluid on the structure, in relation with flow dynamics. The Navier-Stokes equations are numerically solved with a finite element method. Firstly various modes are identified from computational results regarding the flow and forces responses over an oscillation cycle. Flow symmetry properties and vortex patterns are correlated to the time-series of the forces. Besides simulations on long durations compared to the cylinder oscillation period reveal stability domains of the modes in the plane (KC, Re). For some regimes, forces exhibit amplitude fluctuations. They are interpreted notably from forces spectra and flow instabilities. Finally the transition from the problem of one cylinder to the case of a square bundle of 25 cylinders is studied. An energetic approach is proposed to characterize the influence of KC and Re on the global system's behavior, for the isolated cylinder and for the bundle. (author) [fr

  10. 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.

  11. 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.

  12. 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.

  13. Indoor Experimental Assessment of the Efficiency and Irradiance Spot of the Achromatic Doublet on Glass (ADG) Fresnel Lens for Concentrating Photovoltaics.

    Science.gov (United States)

    Vallerotto, Guido; Victoria, Marta; Askins, Stephen; Antón, Ignacio; Sala, Gabriel; Herrero, Rebeca; Domínguez, César

    2017-10-27

    We present a method to characterize achromatic Fresnel lenses for photovoltaic applications. The achromatic doublet on glass (ADG) Fresnel lens is composed of two materials, a plastic and an elastomer, whose dispersion characteristics (refractive index variation with wavelength) are different. We first designed the lens geometry and then used ray-tracing simulation, based on the Monte Carlo method, to analyze its performance from the point of view of both optical efficiency and the maximum attainable concentration. Afterwards, ADG Fresnel lens prototypes were manufactured using a simple and reliable method. It consists of a prior injection of plastic parts and a consecutive lamination, together with the elastomer and a glass substrate to fabricate the parquet of ADG Fresnel lenses. The accuracy of the manufactured lens profile is examined using an optical microscope while its optical performance is evaluated using a solar simulator for concentrator photovoltaic systems. The simulator is composed of a xenon flash lamp whose emitted light is reflected by a parabolic mirror. The collimated light has a spectral distribution and an angular aperture similar to the real Sun. We were able to assess the optical performance of the ADG Fresnel lenses by taking photographs of the irradiance spot cast by the lens using a charge-coupled device (CCD) camera and measuring the photocurrent generated by several types of multi junction (MJ) solar cells, which have been previously characterized at a solar simulator for concentrator solar cells. These measurements have demonstrated the achromatic behavior of ADG Fresnel lenses and, as a consequence, the suitability of the modelling and manufacturing methods.

  14. Teleconnection, Regime Shift, and Predictability of Climate Extremes: A Case Study for the Russian Heat Wave and Pakistan Flood in Summer 2010

    Science.gov (United States)

    Lau, W. K.; Reale, O.; Kim, K.

    2011-01-01

    In this talk, we present observational evidence showing that the two major extremes events of the summer of 2010, i.e., the Russian heat wave and the Pakistan flood were physically connected. We find that the Pakistan flood was contributed by a series of unusually heavy rain events over the upper Indus River Basin in July-August. The rainfall regimes shifted from an episodic heavy rain regime in mid-to-late July to a steady heavy rain regime in August. An atmospheric Rossby wave associated with the development of the Russian heat wave was instrumental in spurring the episodic rain events , drawing moisture from the Bay of Bengal and the northern Arabian Sea. The steady rain regime was maintained primarily by monsoon moisture surges from the deep tropics. From experiments with the GEOS-5 forecast system, we assess the predictability of the heavy rain events associated with the Pakistan flood. Preliminary results indicate that there are significantly higher skills in the rainfall forecasts during the episodic heavy rain events in July, compared to the steady rain period in early to mid-August. The change in rainfall predictability may be related to scale interactions between the extratropics and the tropics resulting in a modulation of rainfall predictability by the circulation regimes.

  15. Detecting phase transitions in a CaCl2-H2O system at low temperatures using a fiber-optic Fresnel reflection sensor.

    Science.gov (United States)

    Priyadarshini, Mani; Machavaram, Venkata Rajanikanth; Sivaramakrishna, Akella; Arulmozhivarman, Pachiyappan

    2017-04-10

    Temperature-induced crystallization events in an aqueous calcium chloride solution in the concentration range of 15-40 mass% are monitored using an optical fiber Fresnel reflection sensor in the temperature range of 30°C to -200°C. The deviation of the phase boundary from equilibrium and the formation of an eutectic mixture followed by its densification during rapid cooling are inferred from the distinct signatures of the optical fiber sensor via the changes in refractive index. During the natural heating at laboratory ambient conditions, the optical signals impart the completion of dissolution of ice and CaCl2·6H2O. The corresponding temperatures have been used in Linke's equations to obtain the salinities, which are in good agreement with the intended solution concentrations. The sensor signal imparts simultaneous melting of the constituents of the eutectic mixture of a 29.7 mass% solution during the natural heating phase. The persistence of the metastable liquid phase at -200°C for tens of minutes followed by solidification is observed at all the concentrations studied. Finally, the feasibility of monitoring phase transitions in a NaCl-CaCl2-H2O system has been demonstrated.

  16. Research on beam characteristics in a large-Fresnel-number unstable-waveguide hybrid resonator with parabolic mirrors.

    Science.gov (United States)

    Wang, Wei; Qin, Yingxiong; Xiao, Yu; Zhong, Lijing; Wu, Chao; Wang, Zhen; Wan, Wen; Tang, Xiahui

    2016-07-20

    Large-Fresnel-number unstable-waveguide hybrid resonators employing spherical resonator mirrors suffer from spherical aberration, which adversely affects beam quality and alignment sensitivity. In this paper, we present experimental and numerical wave-optics simulations of the beam characteristics of a negative-branch hybrid resonator having parabolic mirrors with a large equivalent Fresnel number in the unstable direction. These results are compared with a resonator using spherical mirrors. Using parabolic mirrors, the output beam has a smaller beam spot size and higher power density at the focal plane. We found that the power extraction efficiency is 3.5% higher when compared with a resonator using spherical mirrors as the cavity length was varied between -1 and 1 mm from the ideal confocal resonator. In addition, the power extraction efficiency is 5.6% higher for mirror tilt angles varied between -6 and 6 mrad. Furthermore, the output propagating field is similar to a converging wave for a spherical mirror resonator and the output beam direction deviates 3.5 mrad from the optical axis. The simulation results are in good agreement with the experimental results.

  17. Dynamic modelling and simulation of linear Fresnel solar field model based on molten salt heat transfer fluid

    Science.gov (United States)

    Hakkarainen, Elina; Tähtinen, Matti

    2016-05-01

    Demonstrations of direct steam generation (DSG) in linear Fresnel collectors (LFC) have given promising results related to higher steam parameters compared to the current state-of-the-art parabolic trough collector (PTC) technology using oil as heat transfer fluid (HTF). However, DSG technology lacks feasible solution for long-term thermal energy storage (TES) system. This option is important for CSP technology in order to offer dispatchable power. Recently, molten salts have been proposed to be used as HTF and directly as storage medium in both line-focusing solar fields, offering storage capacity of several hours. This direct molten salt (DMS) storage concept has already gained operational experience in solar tower power plant, and it is under demonstration phase both in the case of LFC and PTC systems. Dynamic simulation programs offer a valuable effort for design and optimization of solar power plants. In this work, APROS dynamic simulation program is used to model a DMS linear Fresnel solar field with two-tank TES system, and example simulation results are presented in order to verify the functionality of the model and capability of APROS for CSP modelling and simulation.

  18. Experimental measurements of a prototype high-concentration Fresnel lens and sun-tracking method for photovoltaic panel's efficiency enhancement

    Science.gov (United States)

    Rajaee, Meraj; Ghorashi, Seyed Mohamad Bagher

    2015-08-01

    Concentrator photovoltaic modules are a promising technology for highly efficient solar energy conversion. This system presents several advantages due to additional degrees of freedom that has been provided by the spectral separation such as cost and mass reduction, increase in the incident solar flux on PV cells and performances. This paper has proposed a unique photovoltaic solar cell system that consists of semi-Fresnel lens convergent structure and a novel two axis sun tracking module to enhance the efficiency of solar cell by using less cell area and energy losses. The grooves of this lens are calculated according to the refraction and convergent angles of the light easy for perpendicular incidence angle. The update time interval during tracking causes misalignment of the lens' optical axis versus the sunrays. Then an inventive sun-tracking method is introduced to adjust the module so that the incident rays are always perpendicular to the module's surface. As a result, all rays will be refracted with the predetermined angles. This way the focus area is reduced and smaller cells can be used. We also mentioned different module connections in order to provide compensation method during losses, for networks and power systems. Experimental results show that using semi-Fresnel lens, along with the sun-tracking method increases the efficiency of PV panel.

  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. Unitary Housing Regimes in Transition

    DEFF Research Database (Denmark)

    Bengtsson, Bo; Jensen, Lotte

    2013-01-01

    to the Danish and Swedish housing regimes are analysed and the responses and outcomes in terms of policy change and/or institutional continuity (path dependence) are compared. Overall, the more decentralized Danish housing regime seems to have resisted pressures for change and retrenchment better so far than...

  4. 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.

  5. 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.

  6. Welfare state regimes, unemployment and health: a comparative study of the relationship between unemployment and self-reported health in 23 European countries.

    Science.gov (United States)

    Bambra, C; Eikemo, T A

    2009-02-01

    The relationship between unemployment and increased risk of morbidity and mortality is well established. However, what is less clear is whether this relationship varies between welfare states with differing levels of social protection for the unemployed. The first (2002) and second (2004) waves of the representative cross-sectional European Social Survey (37 499 respondents, aged 25-60 years). Employment status was main activity in the last 7 days. Health variables were self-reported limiting long-standing illness (LI) and fair/poor general health (PH). Data are for 23 European countries classified into five welfare state regimes (Scandinavian, Anglo-Saxon, Bismarckian, Southern and Eastern). In all countries, unemployed people reported higher rates of poor health (LI, PH or both) than those in employment. There were also clear differences by welfare state regime: relative inequalities were largest in the Anglo-Saxon, Bismarckian and Scandinavian regimes. The negative health effect of unemployment was particularly strong for women, especially within the Anglo-Saxon (OR(LI) 2.73 and OR(PH) 2.78) and Scandinavian (OR(LI) 2.28 and OR(PH) 2.99) welfare state regimes. The negative relationship between unemployment and health is consistent across Europe but varies by welfare state regime, suggesting that levels of social protection may indeed have a moderating influence. The especially strong negative relationship among women may well be because unemployed women are likely to receive lower than average wage replacement rates. Policy-makers' attention therefore needs to be paid to income maintenance, and especially the extent to which the welfare state is able to support the needs of an increasingly feminised European workforce.

  7. Statistical regimes of random laser fluctuations

    International Nuclear Information System (INIS)

    Lepri, Stefano; Cavalieri, Stefano; Oppo, Gian-Luca; Wiersma, Diederik S.

    2007-01-01

    Statistical fluctuations of the light emitted from amplifying random media are studied theoretically and numerically. The characteristic scales of the diffusive motion of light lead to Gaussian or power-law (Levy) distributed fluctuations depending on external control parameters. In the Levy regime, the output pulse is highly irregular leading to huge deviations from a mean-field description. Monte Carlo simulations of a simplified model which includes the population of the medium demonstrate the two statistical regimes and provide a comparison with dynamical rate equations. Different statistics of the fluctuations helps to explain recent experimental observations reported in the literature

  8. 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....

  9. 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.

  10. 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...

  11. Hydrological regimes in Balkan Area

    International Nuclear Information System (INIS)

    Stanescu, Viorel Alexandru

    2004-01-01

    Physical considerations of the deemed area are first considered in the paper. Then the regime types around the Balkan rivers are described in terms of the following characteristic features: -Types of the regimes defined by the timing of the high and low flow phases; -Regionalisation of the 'micro-types' -Stability of the river flow regimes. The available mean monthly discharge data of the representative rivers allows characterising the river regime of the Balkan area covered by WOISYDES and BALWOIS projects. The classification of the hydrological regimes (types of regimes) was done by assessing the discriminant periods (descriptors of the regime phases) defined by the first, the second and the third highest and lowest monthly values of flows. As sufficient data has been provided by countries involved in the Woisydes/Balwois Project a hydrological regionalisation is performed all around the considered space. The existence of different zones, which are quasi- homogeneous in terms of physiographical properties, the latter especially being expressed by their mean altitudes and the climatic features, allowed to carry out a hydrological regionalisation of the river flow regime types. The regionalisation of the river flow regimes is presented as hydrological maps both referring to each Balkan country and for the entire region as an overall map. The stability of a certain flow regime is an important descriptor of the ecological state of the river during the year. It may be quantitatively expressed by the stability coefficient determined by Corbus and Stanescu as the product between the frequency of the occurrence of any discriminant value in m subsequent month (m = 1,12) and a distribution coefficient along the period that depend on the length of the considered discriminant period. The advantage of this method stands in the fact that for several combinations of subsequent months, the maximisation of the stability coefficient leads to the assessment of the characteristic

  12. A Systematic Study of the Quasi-Coherent Mode in the High Density H-Mode Regime of Wendelstein 7-AS

    Science.gov (United States)

    Belonohy, E.; Pokol, G.; McCormick, K.; Papp, G.; Zoletnik, S.

    2008-03-01

    The High Density H-mode (HDH) is a highly promising ELM-free H-mode on the Wendelstein 7-AS (W7-AS) stellarator exhibiting no impurity accumulation. As future fusion-oriented stellarator devices need to run at high densities, a regime often susceptible to impurity accumulation in the standard H-modes of W7-AS, the HDH is of particular interest. The mechanism responsible for the reduced impurity concentration is still undetected and remains a central question in understanding this H-mode. Preliminary results are presented on a possible candidate, a Quasi-Coherent (QC) mode sometimes observed in the HDH regime. The properties of this mode, such as its frequency modulation, frequency and amplitude dependences are discussed as well as its universality with a viewpoint to its possible role in the HDH physics.

  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. STATISTICS OF EXCHANGE RATE REGIMES IN NIGERIA

    African Journals Online (AJOL)

    Admin

    currency. But since transactions are made in national (domestic) currencies, the former is generally applied for exchange (Mordi, 2006). The main objectives of ... different regimes. In this paper, attempt is made to use Autoregressive Integrated Moving Average. (ARIMA) model to study exchange rate data according to ...

  15. Welfare State Regimes and Caseworkers’ Problem Explanation

    DEFF Research Database (Denmark)

    Møller, Marie Østergaard; Stensöta, Helena Helena Olofsdotter

    2018-01-01

    welfare state regime type. Based on in-depth study of caseworker reasoning in Sweden and Denmark, we find a “structural problem explanation” that sees reasons for clients seeking support as rooted in the structures of society— not in the individual client. We find and present two narratives hitherto...

  16. Japan and the Changing Regime of Accumulation: A World-System Study of Japan’s Trajectory From Miracle to Debacle

    Directory of Open Access Journals (Sweden)

    Satoshi Ikeda

    2015-08-01

    Full Text Available Japan’s trajectory under globalization is critically reviewed using the world-system perspective and the methodology of historical sociology. The Japanese miracle in the post-war period was a result of interplay between world-systemic opportunities and internal and regional institutional transformation. Japanese success invited US policy changes, ending the growth regime of accumulation in which state-led national economic development was pursued with distributional concessions given to workers. It is argued that misguided policies based on incorrect economic theories under the strong yen, pushed by the US since 1985, prepared a bubble that then burst. The institutions that had provided the Japanese miracle became the source of problems as Japan entered the debacle period in the 1990s. The Japanese debacle was part of the phenomenon of a ‘prosperous US and the debacle of the rest.’ This development was a result of the change in the regime of accumulation from a growth regime to a distribution regime where the rentier class took control of distribution and the project of national economic development was replaced by the monopolistic competition of global corporations. For Japan, both traditionalism and neo-liberalism are dysfunctional. In the short run, Japan as a society needs to focus on survival and the maintenance of people’s living standards under the new rules of the accumulation game imposed by the US. In the medium run, Japan needs to challenge US dollar hegemony ushered in by the new rules. In the long run, the Japanese need to examine whether they should keep engaging in the game of capitalist accumulation.

  17. 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

  18. 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.

  19. 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.

  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. Direct comparison of polymethylmetacrylate (PMMA) and silicone-on-glass (SOG) for Fresnel lenses in concentrating photovoltaics (CPV)

    Science.gov (United States)

    Annen, Hans Philipp; Fu, Ling; Leutz, Ralf; González, Luis; Mbakop, Jehu

    2011-09-01

    The CPV community is still undecided on one critical issue: what material to use best for Fresnel lens parquets. Reliability and longevity are the most important, but all other properties play roles as well. We have developed and manufactured Fresnel lenses with the two commonly used materials: PMMA (Polymethylmethacrylate) and silicone on glass (SOG). Both lenses are designed for the same optical train for best comparability. This allows for better understanding the pros and cons of the materials and making an informed choice for a specific CPV module. While PMMA lenses are embossed from pre-fab sheets in a hot-cold process, the silicone lenses are cast from a heat-curing silicone rubber at moderate temperatures, reducing the energy consumption. PMMA allows for the inclusion of custom low-profile 3D (2.5D) structures for module assembly and mechanical alignment, a feature not possible in silicone due to its low rigidity. Both lenses suffer from thermal expansion and refractive index change. While PMMA parquets expand isotropically, SOG prisms deform due to the difference of expansion coefficients between the glass and the silicone. SOG lenses are prone to delamination of the silicone film. The adhesive strength of the film to the glass can be measured using a modified blister test that we developed. The results show large difference with different materials and confirm the necessity of controlling this issue closely. While the small thermal expansion of the glass sheets allows for larger parquet sizes, the deformation of the prisms with temperature may cause a performance hit.

  2. Transitions between risk management regimes in cities

    Directory of Open Access Journals (Sweden)

    William Solecki

    2017-06-01

    Full Text Available Ongoing climate change is encouraging cities to reevaluate their risk management strategies. Urban communities increasingly are being forced to respond to climate shifts with actions that promote resistance, resilience, or even larger scale transformations. Our objective is to present a conceptual framework that facilitates examination of how the transition from one type of risk management strategy or regime to another takes place. The research framework is built around a set of assumptions regarding the process of transition between risk management regimes. The framework includes five basic conceptual elements: (1 risk management regimes, (2 development pathways, (3 activity spheres, (4 activity spaces, and (5 root, contextual, and proximate drivers. The interaction among these elements and the potential for transition between four different possible regime states including resistance, resilience, transformation, and collapse are presented. The framework facilitates and guides analysis on whether and how transition is emergent, constrained, or accelerated in specific contexts. A case study of post-Hurricane Sandy New York is used to illustrate the framework and its overall effectiveness.

  3. Early signatures of regime shifts in complex dynamical systems

    Indian Academy of Sciences (India)

    2015-02-05

    Feb 5, 2015 ... A large number of studies have recently been carried out on the early signatures of regime shifts in a number of dynamical systems, e.g., ecosystems, the climate, fish and wildlife populations, ... Noise-induced regime shifts are also possible for which the vicinity of the bifurcation point is not essential. In this ...

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.)

  9. 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)

  10. Properties of bosons in a one-dimensional bichromatic optical lattice in the regime of the pinning transition: A worm-algorithm Monte Carlo study

    Science.gov (United States)

    Sakhel, Asaad R.

    2016-09-01

    The sensitivity of the pinning transition (PT) as described by the sine-Gordon model of strongly interacting bosons confined in a shallow, one-dimensional, periodic optical lattice (OL), is examined against perturbations of the OL. The PT has been recently realized experimentally by Haller et al. [Nature (London) 466, 597 (2010), 10.1038/nature09259] and is the exact opposite of the superfluid-to-Mott-insulator transition in a deep OL with weakly interacting bosons. The continuous-space worm-algorithm (WA) Monte Carlo method [Boninsegni et al., Phys. Rev. E 74, 036701 (2006), 10.1103/PhysRevE.74.036701] is applied for the present examination. It is found that the WA is able to reproduce the PT, which is another manifestation of the power of continuous-space WA methods in capturing the physics of phase transitions. In order to examine the sensitivity of the PT, it is tweaked by the addition of the secondary OL. The resulting bichromatic optical lattice (BCOL) is considered with a rational ratio of the constituting wavelengths λ1 and λ2 in contrast to the commonly used irrational ratio. For a weak BCOL, it is chiefly demonstrated that this PT is robust against the introduction of a weaker, secondary OL. The system is explored numerically by scanning its properties in a range of the Lieb-Liniger interaction parameter γ in the regime of the PT. It is argued that there should not be much difference in the results between those due to an irrational ratio λ1/λ2 and those due to a rational approximation of the latter, bringing this in line with a recent statement by Boers et al. [Phys. Rev. A 75, 063404 (2007), 10.1103/PhysRevA.75.063404]. The correlation function, Matsubara Green's function (MGF), and the single-particle density matrix do not respond to changes in the depth of the secondary OL V1. For a stronger BCOL, however, a response is observed because of changes in V1. In the regime where the bosons are fermionized, the MGF reveals that hole excitations are

  11. 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....

  12. 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.

  13. How Welfare Regimes Generate and Erode Social Capital

    DEFF Research Database (Denmark)

    Larsen, Christian Albrekt

    2007-01-01

    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...... 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...... 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....

  14. intensive and extensive feeding regimes

    African Journals Online (AJOL)

    production and reproduction parameters in ram lambs, under intensive and extensive feeding regimes. J.P.C. Greyling* and G.J. Taylor. Department of Animal Science, University of the Orange Free State, PO. Box 339, Bloemfontein,. 9300, South Africa. Received revised 1 July 1999; accepted 28 July 1999. Forty Dorper ...

  15. 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

  16. 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

  17. Non-minimal Einstein–Maxwell theory: the Fresnel equation and the Petrov classification of a trace-free susceptibility tensor

    Science.gov (United States)

    Balakin, Alexander B.; Zayats, Alexei E.

    2018-03-01

    We construct a classification of dispersion relations for electromagnetic waves non-minimally coupled to space-time curvature, based on analysis of the susceptibility tensor which appears in the non-minimal Einstein–Maxwell theory. We classify solutions to the Fresnel equation for the model with a trace-free non-minimal susceptibility tensor according to the Petrov scheme. For all Petrov types we discuss specific features of the dispersion relations, and plot the corresponding wave surfaces.

  18. 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...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....

  19. 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...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....

  20. Atmospheric Water-Cycle Regimes and Cloud Regimes

    Science.gov (United States)

    Wong, S.; Fetzer, E. J.; L'Ecuyer, T. S.

    2013-12-01

    The relationship between the atmospheric water vapor budget and cloud properties is investigated by collocated reanalysis fields from Modern Era Retrospective-analysis for Research and Applications (MERRA) and the observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite instrument. Intensities of surface water exchange (precipitation minus evaporation) are analyzed in the space of 'dynamical regimes', which are defined by combination of large-scale water vapor advection and convergence calculated from the MERRA. The atmospheric water vapor sinks associated with mid-latitude storm systems and precipitation in the west coast of United States are mainly driven by the large-scale dynamical advection, while those associated with tropical deep convection and summertime monsoons are mainly driven by water vapor convergence. Subtropical subsidence area over the eastern ocean basins is dominated by strong water vapor divergence. These dynamical regimes are then connected to the collocated MODIS cloud top pressure and cloud optical thickness. Probability density distributions of these MODIS cloud properties associated with each dynamical regime will be presented.

  1. 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

  2. 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.

  3. 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.

  4. Quantification of mesenchymal stem cell growth rates through secretory and excretory biomolecules in conditioned media via Fresnel reflection.

    Science.gov (United States)

    Ahmad, Harith; Thambiratnam, Kavintheran; Zulkifli, Ahmad Z; Lawrence, Anthony; Jasim, Ali A; Kunasekaran, Wijenthiran; Musa, Sabri; Gnanasegaran, Nareshwaran; Vasanthan, Punitha; Jayaraman, Pukana; Kasim, Noor H A; Govindasamy, Vijayendran; Shahrir, Mohammad S; Harun, Sulaiman W

    2013-09-30

    An efficient and low cost optical method for directly measuring the concentration of homogenous biological solutes is proposed and demonstrated. The proposed system operates by Fresnel reflection, with a flat-cleaved single-mode fiber serving as the sensor probe. A laser provides a 12.9 dBm sensor signal at 1,550 nm, while a computer-controlled optical power meter measures the power of the signal returned by the probe. Three different mesenchymal stem cell (MSC) lines were obtained, sub-cultured and trypsinized daily over 9 days. Counts were measured using a haemocytometer and the conditioned media (CM) was collected daily and stored at -80 °C. MSCs release excretory biomolecules proportional to their growth rate into the CM, which changes the refractive index of the latter. The sensor is capable of detecting changes in the number of stem cells via correlation to the change in the refractive index of the CM, with the measured power loss decreasing approximately 0.4 dB in the CM sample per average 1,000 cells in the MSC subculture. The proposed system is highly cost-effective, simple to deploy, operate, and maintain, is non-destructive, and allows reliable real-time measurement of various stem cell proliferation parameters.

  5. 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)

  6. 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.

  7. 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.

  8. Constraints on flow regimes in wide-aperture fractures

    Energy Technology Data Exchange (ETDEWEB)

    Ghezzehei, Teamrat A.

    2004-02-28

    In recent years, significant advances have been made in our understanding of the complex flow processes in individual fractures, aided by flow visualization experiments and conceptual modeling efforts. These advances have led to the recognition of several flow regimes in individual fractures subjected to different initial and boundary conditions. Of these, the most important regimes are film flow, rivulet flow, and sliding of droplets. The existence of such significantly dissimilar flow regimes has been a major hindrance in the development of self-consistent conceptual models of flow for single fractures that encompass all the flow regimes. The objective of this study is to delineate the existence of the different flow regimes in individual fractures. For steady-state flow conditions, we developed physical constraints on the different flow regimes that satisfy minimum energy configurations, which enabled us to segregate the wide range of fracture transmissivity (volumetric flow rate per fracture width) into several flow regimes. These are, in increasing order of flow rate, flow of adsorbed films, flow of sliding drops, rivulet flow, stable film flow, and unstable (turbulent) film flow. The scope of this study is limited to wide-aperture fractures with the flow on the opposing sides of fracture being independent.

  9. [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.

  10. Crossflow and water banks in viscous dominant regimes of waterflooding

    DEFF Research Database (Denmark)

    Yuan, Hao; Zhang, Xuan; Shapiro, Alexander

    2014-01-01

    Understanding the crossflow in multilayered reservoirs is of great importance for designing mobility control methods for enhanced oil recovery. The authors reveal saturation profiles in stratified reservoirs to study the interlayer communication in the viscous dominant regime. The displacement...

  11. 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)

  12. 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.

  13. Implementation Regimes and Street-Level Bureaucrats

    DEFF Research Database (Denmark)

    Winter, Søren; T. Dinesen, Peter; J. May, Peter

    -government regimes foster greater policy commitment, attention to rules, and adherence among frontline workers than is the case for a local-government implementation regime. These lead to actions of street-level bureaucrats in central-government regimes that are more in line with national policies than those...

  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. Performances d’une centrale à concentrateur de Fresnel de moyenne puissance sur sites Algériens

    Directory of Open Access Journals (Sweden)

    H. Beltagy

    2014-03-01

    Full Text Available L’objectif du présent travail est de caractériser une centrale à concentrateur de Fresnel de moyenne puissance (5MWe sur différents sites Algériens (Sahara, ces sites ont été choisis pour comparaison en déplaçant la centrale dans ces derniers, à savoir Hassi-R’mel, Tamanrasset, Béni-Abbes, et El Oued. Une modélisation théorique a permis la détermination du nombre optimum des miroirs à ne pas dépasser pour éviter les effets d’ombre, blocage et l’effet cosinus. Le nombre optimum de miroirs a été estimé à 40 miroirs. Par ailleurs, une simulation a été réalisée à l’échelle horaire : elle concerne l’ensoleillement, le système ‘champ’, et le système ‘récepteur’. Les résultats de la simulation sont représentés en moyenne annuels. Les rendements, la production énergétique annuelle, et le coût du kWh sont évalués. En effet, le calcul du rendement diffère d’un site à un autre avec des valeurs de 15.7%, 11.8%,11.6%, et 10.4% respectivement pour les sites Tamanrasset, El Oued, Béni-Abbes, Hassi R’mel. Les performances thermiques et les résultats technico-économiques sont évalués aussi pour ces mêmes sites.

  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. 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

  18. Criptografía óptica mediante difracción de Fresnel y conjugación de fase

    Directory of Open Access Journals (Sweden)

    Jorge Enrique Rueda-Parada

    2013-01-01

    Full Text Available Se implementó un procesador óptico para cifrar imágenes usando difracción de Fresnel en el espacio libre. Utilizamos mezcla de cuatro ondas para grabar la imagen cifrada en un cristal fotorrefractivo BSO y decodifi camos la misma por conjugación de fase. En cada imagen cifrada sólo utilizamos una llave. Nosotros caracterizamos el procesador en términos de los valores de fase de la llave, y determinamos el límite inferior del valor medio de la fase en el cual se obtuvo un cifrado total. El procesador opera en tiempo real.

  19. Convective Replica-Exchange in Ergodic Regimes.

    Science.gov (United States)

    Signorini, Giorgio F; Giovannelli, Edoardo; Spill, Yannick G; Nilges, Michael; Chelli, Riccardo

    2014-03-11

    In a recent article (J. Comput. Chem. 2013, 34, 132-140), convective replica-exchange (convective-RE) has been presented as an alternative to the standard even-odd transition scheme. Computations on systems of various complexity have shown that convective-RE may increase the number of replica round-trips in temperature space with respect to the standard exchange scheme, leading to a more effective sampling of energy basins. Moreover, it has been shown that the method may prevent the formation of bottlenecks in the diffusive walk of replicas through the space of temperature states. By using an ideal temperature-RE model and a classical harmonic-oscillator RE scheme, we study the performances of convective-RE when ergodicity is not broken and convergence of acceptance probabilities is attained. In this dynamic regime, the round-trip ratio between convective and standard-RE is at maximum ∼ 1.5, a value much smaller than that observed in nonergodic simulations. For large acceptance probabilities, the standard-RE outperforms convective-RE. Our observations suggest that convective-RE can safely be used in either ergodic or non-ergodic regimes; however, convective-RE is advantageous only when bottlenecks occur in the state-space diffusion of replicas, or when acceptance probabilities are globally low. We also show that decoupling of the state-space dynamics of the stick replica from the dynamics of the remaining replicas improves the efficiency of convective-RE at low acceptance probability regimes.

  20. 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.

  1. 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

  2. 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...

  3. 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.

  4. 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

  5. Three novel tokamak plasma regimes in TFTR

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Flow regime identification methodology with computerized tomography

    International Nuclear Information System (INIS)

    Teixeira, Alberto Ramon Ferreira; Roberty, Nilson Costa

    2010-01-01

    This work presents a flow identification methodology in multiphase system in stratified oil-water-gas regime. The principle is based on detecting the amount of x-rays attenuated by passing through the duct containing the flow. The radiation interacts with the material and the composite duct fluid, causing the intensity of X ray declines. In this study, was used divergent bean into two and three dimensions. In this case we need to know the source position in order to back project the rays accordingly in a divergent way. In three dimensions, the projections discontinuity determination problem is substituted by the projections images contour determination. Each ray generates one algebraic equation. The system may be solved by the least square method or by some algebraic reconstruction technique such as the ART, MART or q-ART algorithms. The experiment shows that with a single view (a source-detector pair) it is possible to obtain information of a flow inside a duct (the attenuation of the radiation beam). However, it is not possible to make the reconstruction of the flow. Then, we use two views, so getting enough information to reconstruct the flow. The results presented show that the technique may be applied in the successfully flow regime identification. (author)

  7. Elastic regimes of subisostatic athermal fiber networks

    Science.gov (United States)

    Licup, A. J.; Sharma, A.; MacKintosh, F. C.

    2016-01-01

    Athermal models of disordered fibrous networks are highly useful for studying the mechanics of elastic networks composed of stiff biopolymers. The underlying network architecture is a key aspect that can affect the elastic properties of these systems, which include rich linear and nonlinear elasticity. Existing computational approaches have focused on both lattice-based and off-lattice networks obtained from the random placement of rods. It is not obvious, a priori, whether the two architectures have fundamentally similar or different mechanics. If they are different, it is not clear which of these represents a better model for biological networks. Here, we show that both approaches are essentially equivalent for the same network connectivity, provided the networks are subisostatic with respect to central force interactions. Moreover, for a given subisostatic connectivity, we even find that lattice-based networks in both two and three dimensions exhibit nearly identical nonlinear elastic response. We provide a description of the linear mechanics for both architectures in terms of a scaling function. We also show that the nonlinear regime is dominated by fiber bending and that stiffening originates from the stabilization of subisostatic networks by stress. We propose a generalized relation for this regime in terms of the self-generated normal stresses that develop under deformation. Different network architectures have different susceptibilities to the normal stress but essentially exhibit the same nonlinear mechanics. Such a stiffening mechanism has been shown to successfully capture the nonlinear mechanics of collagen networks.

  8. 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.

  9. 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.

  10. State Structure and Political Regime Structure

    OpenAIRE

    Paul – Iulian Nedelcu

    2012-01-01

    The political regime is the concrete form of organization and functioning of political system andtherefore, the regime means the concrete way of organize, institutionalize and function a political systemand of the exercise of political power by a social-political force in a social community or global socialistem. The political regime is not limited to institutions and state bodies, but it covers the entire politicalsystem. Form of expression in social practice plan is the result of balance of...

  11. 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 ...

  12. Experimental Study of the Kinetics of Drying of Thin Plane Moist Materials by the Regular-Regime Method Using Generalized Complex Variables

    Science.gov (United States)

    Ol'shanskii, A. I.; Gusarov, A. M.

    2017-05-01

    Results of experimental study of the kinetics of drying of thin materials have been presented. Fundamental experimental equations to calculate the kinetic parameters of the process of drying, i.e., the heat-flux density, the integral mean temperature, and the duration of drying, have been given.

  13. 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

  14. Study of Third-Order Optical Nonlinearities of Se-Sn (Bi,Te) Quaternary Chalcogenide Thin Films Using Ti: Sapphire Laser in Femtosecond Regime

    Science.gov (United States)

    Yadav, Preeti; Sharma, Ambika

    2017-01-01

    The objective of the present research work is to study the nonlinear optical properties of quaternary Se-Sn (Bi,Te) chalcogenide thin films. A Z-scan technique utilizing 800 nm femtosecond laser source has been used for the determination of the nonlinear refractive index ( n 2), two-photon absorption coefficient ( β 2) and third-order susceptibility ( χ (3)). In the measurement of n 2, an aperture is placed in the far field before the detector (closed aperture), while for the measurement of β 2, entire transmitted light is collected by the detector without an aperture (open aperture). Self-focusing has been observed in closed aperture transmission spectra. The appearance of the peak after the valley in this spectrum reflects the positive nonlinear refractive index. The calculated value of n 2 of the studied thin films varies from 1.06 × 10-12 cm2/W to 0.88 × 10-12 cm2/W. The compound-dependent behavior of n 2 is explained in this paper. We have also compared the experimental values of n 2 with the theoretically determined values, other compounds of chalcogenide glass and pure silica. The n 2 of the investigated thin films is found to be 3200 times higher than pure silica. The results of the open aperture Z-scan revealed that the value of β 2 of the studied compound is in the order of 10-8 cm/W. The behavior of two-photon absorption is described by means of the optical band gap ( E g) of the studied compound. The variation in the figure-of-merit from 0.32 to 1.4 with varying Sn content is also reported in this paper. The higher value of nonlinearity makes this material advantageous for optical fibers, waveguides and optical limiting devices.

  15. How well has land-use planning worked under different governance regimes? A case study in the Portland, OR-Vancouver, WA metropolitan area, USA

    Science.gov (United States)

    Jeffrey D. Kline; Paul Thiers; Connie P. Ozawa; J. Alan Yeakley; Sean N. Gordon

    2014-01-01

    We examine land use planning outcomes over a 30-year period in the Portland, OR-Vancouver, WA (USA) metropolitan area. The four-county study region enables comparisons between three Oregon counties subject to Oregon’s 1973 Land Use Act (Senate Bill 100) and Clark County, WA which implemented land use planning under Washington’s 1990 Growth Management Act. We describe...

  16. 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+ 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.

  17. 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

  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. 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.

  20. 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

  1. 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.)

  2. 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.

  3. 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.

  4. 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

  5. Synergies between nonproliferation regimes: A pragmatic approach

    International Nuclear Information System (INIS)

    Findlay, Trevor; Meier, Oliver

    2001-01-01

    Full text: With the recent progress in establishing international nonproliferation regimes, the question of synergies between different verification and monitoring regimes is becoming more acute. Three multilateral and universal nonproliferation organisations covering safeguards on civil nuclear materials, nuclear testing, and chemical weapons are up and running. A regime on biological weapons is under negotiation. Several regional organisations concerned with monitoring nonproliferation commitments in the nuclear field are in place; others are being established. Past discussions on synergies between these regimes have suffered from being too far-reaching. These discussions often have not reflected adequately the political difficulties of cooperation between regimes with different membership, scope and institutional set-up. This paper takes a pragmatic look at exploiting synergies and identifies some potential and real overlaps in the work between different verification regimes. It argues for a bottom-up approach and identifies building blocks for collaboration between verification regimes. By realising such, more limited potential for cooperation, the ground could be prepared for exploiting other synergies between these regimes. (author)

  6. Targeting autocrats : Economic sanctions and regime change

    NARCIS (Netherlands)

    Oechslin, M.C.

    2014-01-01

    When it comes to international economic sanctions, the most frequent goal is regime change and democratization. Yet, past experiences suggest that such sanctions are often ineffective; moreover, quite paradoxically, targeted regimes tend to respond with policies that amplify the sanctions’ harmful

  7. 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

  8. Decentralization and Diversification in Forest Management Regimes ...

    African Journals Online (AJOL)

    In recent years in many African countries, including Tanzania, there has been a shift of paradigm from centralized and state driven forest management regimes to decentralized and people- centred forest management regime. The inception of a Tanzania forest policy of 1998 resulted in the institutionalization of community ...

  9. Multiscale regime shifts and planetary boundaries

    NARCIS (Netherlands)

    Hughes, T.P.; Carpenter, S.; Rockstrom, J.; Scheffer, M.; Walker, B.

    2013-01-01

    Life on Earth has repeatedly displayed abrupt and massive changes in the past, and there is no reason to expect that comparable planetary-scale regime shifts will not continue in the future. Different lines of evidence indicate that regime shifts occur when the climate or biosphere transgresses a

  10. LEGAL MATRIMONIAL REGIME IN B&H

    Directory of Open Access Journals (Sweden)

    Boris Krešić

    2011-12-01

    Full Text Available Matrimonial regime between spouses or between extramarital partners, and between parents and children is regulated by the Family Law Act of Bosnia and Herzegovina Federation, hereinafter FLA B&HF (SG FBiH 35/05, 41/05, Family Law Act of the Republic of Srpska, hereinafter FLA RS (SG RS”54/02, 41/08 and the Family Law Act of Brčko District, hereinafter FLA BD (SG RS, 66/07. Legal rules used for the regulation of the matrimonial regime between spouses, as well as between spouses and third parties make matrimonial regime (Ponjavić, 2005, p. 361. Matrimonial regime between spouses in family legislation in Bosnia and Herzegovina (B&H is regulated in two following ways: as legal matrimonial regime and as contract matrimonial regime. Legal regime is the one which applies on spouses if not arranged otherwise prior to contracting marriage or during marriage. In this paper the author indicates the differences between the legal matrimonial regimes of the two entities as well as those between the entities and Brčko District of Bosnia and Herzegovina.

  11. Alumina strength degradation in the elastic regime

    International Nuclear Information System (INIS)

    Furnish, Michael D.; Chhabildas, Lalit C.

    1998-01-01

    Measurements of Kanel et al. [1991] have suggested that deviatoric stresses in glasses shocked to nearly the Hugoniot Elastic Limit (HEL) relax over a time span of microseconds after initial loading. 'Failure' (damage) waves have been inferred on the basis of these measurements using time-resolved manganin normal and transverse stress gauges. Additional experiments on glass by other researchers, using time-resolved gauges, high-speed photography and spall strength determinations have also lead to the same conclusions. In the present study we have conducted transmitted-wave experiments on high-quality Coors AD995 alumina shocked to roughly 5 and 7 GPa (just below or at the HEL). The material is subsequently reshocked to just above its elastic limit. Results of these experiments do show some evidence of strength degradation in the elastic regime

  12. Dynamic portfolio optimization across hidden market regimes

    DEFF Research Database (Denmark)

    Nystrup, Peter; Madsen, Henrik; Lindström, Erik

    2017-01-01

    Regime-based asset allocation has been shown to add value over rebalancing to static weights and, in particular, reduce potential drawdowns by reacting to changes in market conditions. The predominant approach in previous studies has been to specify in advance a static decision rule for changing...... the allocation based on the state of financial markets or the economy. In this article, model predictive control (MPC) is used to dynamically optimize a portfolio based on forecasts of the mean and variance of financial returns from a hidden Markov model with time-varying parameters. There are computational...... advantages to using MPC when estimates of future returns are updated every time a new observation becomes available, since the optimal control actions are reconsidered anyway. MPC outperforms a static decision rule for changing the allocation and realizes both a higher return and a significantly lower risk...

  13. Convection and exchangers in variable regime; Convection et echangeurs en regime variable

    Energy Technology Data Exchange (ETDEWEB)

    Bagui, F.; Abdelghani-Idrissi, M.A. [Rouen Univ. IUT, Centre de Developpement Durable, 76 - Mont Saint Aignan (France); Bagui, F. [Ecole d' Ingenieurs CESI, 76 - Mont Saint Aignan (France); Desmet, B.; Lalot, S.; Harmand, S. [Valenciennes et du Hainaut-Cambresis Univ., Lab. de Mecanique et Energetique, 59 - Valenciennes (France); Maillet, D. [Institut National Polytechnique, INPL-UHP Nancy-1, LEMTA-CNRS UMR 7563, 54 - Vandoeuvre les Nancy (France)

    2005-07-01

    This session about convection and exchangers in variable regime gathers three articles dealing with: the transient regimes of tubular heat exchangers; heat exchangers and convection in non-permanent regime; and the limitations of the H coefficient: two short-time and short-scale examples. (J.S.)

  14. CRM in the Regime of Nonresonant Bunching

    CERN Document Server

    Bandurkin, I V; Savilov, A V

    2005-01-01

    New regime of electron-wave coupling in cyclotron resonance maser (CRM) is proposed. In this regime, during the most part of interaction process electrons move in the field of rf wave which is relatively far from cyclotron resonance. It is shown, that if resonance mismatch is chosen properly, an effective bunching takes place, an amplitude of forming rf current weakly depending on the velocity spread. Simulations show that, whereas the efficiency of traditional regimes quickly decreases with increasing velocity spread, efficiency of the proposed scheme practically does not change and for relative value of spread in transverse velocities of 40% is twice as large as corresponding efficiency of the conventional regimes. The regime seems to be also prospective for realization of CRM with frequency multiplication. In such a scheme, resonance mismatch for low-frequency wave in bunching section should be such that high-frequency wave be in resonance with the beam. Thus, the device operates like the single-frequency ...

  15. Control of Synchronization Regimes in Networks of Mobile Interacting Agents

    Science.gov (United States)

    Perez-Diaz, Fernando; Zillmer, Ruediger; Groß, Roderich

    2017-05-01

    We investigate synchronization in a population of mobile pulse-coupled agents with a view towards implementations in swarm-robotics systems and mobile sensor networks. Previous theoretical approaches dealt with range and nearest-neighbor interactions. In the latter case, a synchronization-hindering regime for intermediate agent mobility is found. We investigate the robustness of this intermediate regime under practical scenarios. We show that synchronization in the intermediate regime can be predicted by means of a suitable metric of the phase response curve. Furthermore, we study more-realistic K -nearest-neighbor and cone-of-vision interactions, showing that it is possible to control the extent of the synchronization-hindering region by appropriately tuning the size of the neighborhood. To assess the effect of noise, we analyze the propagation of perturbations over the network and draw an analogy between the response in the hindering regime and stable chaos. Our findings reveal the conditions for the control of clock or activity synchronization of agents with intermediate mobility. In addition, the emergence of the intermediate regime is validated experimentally using a swarm of physical robots interacting with cone-of-vision interactions.

  16. Vegetation management with fire modifies peatland soil thermal regime.

    Science.gov (United States)

    Brown, Lee E; Palmer, Sheila M; Johnston, Kerrylyn; Holden, Joseph

    2015-05-01

    Vegetation removal with fire can alter the thermal regime of the land surface, leading to significant changes in biogeochemistry (e.g. carbon cycling) and soil hydrology. In the UK, large expanses of carbon-rich upland environments are managed to encourage increased abundance of red grouse (Lagopus lagopus scotica) by rotational burning of shrub vegetation. To date, though, there has not been any consideration of whether prescribed vegetation burning on peatlands modifies the thermal regime of the soil mass in the years after fire. In this study thermal regime was monitored across 12 burned peatland soil plots over an 18-month period, with the aim of (i) quantifying thermal dynamics between burned plots of different ages (from vegetation management. Compared to plots burned 15 + years previously, plots recently burned (vegetation regrows. Our findings that prescribed peatland vegetation burning alters soil thermal regime should provide an impetus for further research to understand the consequences of thermal regime change for carbon processing and release, and hydrological processes, in these peatlands. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  17. Cooling in the single-photon regime of optomechanics

    Science.gov (United States)

    Nunnenkamp, Andreas; Borkje, Kjetil; Girvin, Steven

    2012-02-01

    Optomechanics experiments are rapidly approaching the regime where the radiation pressure of a single photon displaces the mechanical oscillator by more than its zero-point uncertainty. We show that in this limit the power spectrum has multiple sidebands and that the cavity response has several resonances in the resolved-sideband limit [Phys. Rev. Lett. 107, 063602 (2011)]. We then discuss how red-sideband cooling is modified in this nonlinear regime. Using Fermi's Golden rule we calculate the transition rates induced by the optical drive. In the resolved-sideband limit we find multiple cooling resonances for strong single-photon coupling. They lead to non-thermal steady states and are accompanied by multiple mechanical sidebands in the optical output spectrum. Our study provides the tools to detect and take advantage of this novel regime of optomechanics.

  18. Intergenerational Justice Perceptions and the Role of Welfare Regimes

    DEFF Research Database (Denmark)

    Sabbagh, Clara; Vanhuysse, Pieter

    2010-01-01

    This article studies perceptions of intergenerational justice among 2,075 undergraduate university students from eight democracies spanning four different models, or 'worlds,' of welfare. We examine two different, though interrelated, aspects of intergenerational justice: (1) whether, and how......, different welfare regimes structure young people's perceptions of the justness of public resources transfers from young to elderly age-groups and (2) the perceived relative contributions and rewards of various age-groups. Thus we inquire about both the perceived support in principle and about the perceived...... justness of actual outcomes of resource transfers between age-groups. We find that support of transfers from the young to the old is higher in social-democratic and conservative welfare regimes than in liberal and radical regimes. Support of resource transfers also correlates positively with a 'welfare...

  19. Deterministic-random separation in nonstationary regime

    Science.gov (United States)

    Abboud, D.; Antoni, J.; Sieg-Zieba, S.; Eltabach, M.

    2016-02-01

    In rotating machinery vibration analysis, the synchronous average is perhaps the most widely used technique for extracting periodic components. Periodic components are typically related to gear vibrations, misalignments, unbalances, blade rotations, reciprocating forces, etc. Their separation from other random components is essential in vibration-based diagnosis in order to discriminate useful information from masking noise. However, synchronous averaging theoretically requires the machine to operate under stationary regime (i.e. the related vibration signals are cyclostationary) and is otherwise jeopardized by the presence of amplitude and phase modulations. A first object of this paper is to investigate the nature of the nonstationarity induced by the response of a linear time-invariant system subjected to speed varying excitation. For this purpose, the concept of a cyclo-non-stationary signal is introduced, which extends the class of cyclostationary signals to speed-varying regimes. Next, a "generalized synchronous average'' is designed to extract the deterministic part of a cyclo-non-stationary vibration signal-i.e. the analog of the periodic part of a cyclostationary signal. Two estimators of the GSA have been proposed. The first one returns the synchronous average of the signal at predefined discrete operating speeds. A brief statistical study of it is performed, aiming to provide the user with confidence intervals that reflect the "quality" of the estimator according to the SNR and the estimated speed. The second estimator returns a smoothed version of the former by enforcing continuity over the speed axis. It helps to reconstruct the deterministic component by tracking a specific trajectory dictated by the speed profile (assumed to be known a priori).The proposed method is validated first on synthetic signals and then on actual industrial signals. The usefulness of the approach is demonstrated on envelope-based diagnosis of bearings in variable

  20. How will climate change modify river flow regimes in Europe?

    Directory of Open Access Journals (Sweden)

    C. Schneider

    2013-01-01

    Full Text Available Worldwide, flow regimes are being modified by various anthropogenic impacts and climate change induces an additional risk. Rising temperatures, declining snow cover and changing precipitation patterns will interact differently at different locations. Consequently, in distinct climate zones, unequal consequences can be expected in matters of water stress, flood risk, water quality, and food security. In particular, river ecosystems and their vital ecosystem services will be compromised as their species richness and composition have evolved over long time under natural flow conditions. This study aims at evaluating the exclusive impacts of climate change on river flow regimes in Europe. Various flow characteristics are taken into consideration and diverse dynamics are identified for each distinct climate zone in Europe. In order to simulate present-day natural flow regimes and future flow regimes under climate change, the global hydrology model WaterGAP3 is applied. All calculations for current and future conditions (2050s are carried out on a 5' × 5' European grid. To address uncertainty, bias-corrected climate forcing data of three different global climate models are used to drive WaterGAP3. Finally, the hydrological alterations of different flow characteristics are quantified by the Indicators of Hydrological Alteration approach. Results of our analysis indicate that on the European scale, climate change can be expected to modify flow regimes remarkably. This is especially the case in the Mediterranean (due to drier conditions with reduced precipitation across the year and in the boreal climate zone (due to reduced snowmelt, increased precipitation, and strong temperature rises. In the temperate climate zone, impacts increase from oceanic to continental. Regarding single flow characteristics, strongest impacts on timing were found for the boreal climate zone. This applies for both high and low flows. Flow magnitudes, in turn, will be

  1. Modeling whistler wave generation regimes in magnetospheric cyclotron maser

    Directory of Open Access Journals (Sweden)

    D. L. Pasmanik

    2004-11-01

    Full Text Available Numerical analysis of the model for cyclotron instability in the Earth's magnetosphere is performed. 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. A parametric study of the model is performed. 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 its intensity. Two mechanisms of removal of energetic electrons from a generation region are considered, one is due to the particle precipitation through the loss cone and another one is related to the magnetic drift of energetic particles. It was confirmed that two main regimes occur in this system in the presence of a constant particle source, in the case of precipitation losses. At small source intensity relaxation oscillations were found, whose parameters are in good agreement with simplified analytical theory developed earlier. At a larger source intensity, transition to a periodic generation occurs. In the case of drift losses the regime of self-sustained periodic generation regime is realized for source intensity higher than some threshold. The dependencies of repetition period and dynamic spectrum shape on the source parameters were studied in detail. In addition to simple periodic regimes, those with more complex spectral forms were found. In particular, alteration of spikes with different spectral shape can take place. It was also shown that quasi-stationary generation at the low-frequency band can coexist with periodic modulation at higher frequencies. On the basis of the results obtained, the model for explanation of quasi-periodic whistler wave emissions is verified.

  2. Modeling whistler wave generation regimes in magnetospheric cyclotron maser

    Directory of Open Access Journals (Sweden)

    D. L. Pasmanik

    2004-11-01

    Full Text Available Numerical analysis of the model for cyclotron instability in the Earth's magnetosphere is performed. 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. A parametric study of the model is performed. 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 its intensity. Two mechanisms of removal of energetic electrons from a generation region are considered, one is due to the particle precipitation through the loss cone and another one is related to the magnetic drift of energetic particles.

    It was confirmed that two main regimes occur in this system in the presence of a constant particle source, in the case of precipitation losses. At small source intensity relaxation oscillations were found, whose parameters are in good agreement with simplified analytical theory developed earlier. At a larger source intensity, transition to a periodic generation occurs. In the case of drift losses the regime of self-sustained periodic generation regime is realized for source intensity higher than some threshold. The dependencies of repetition period and dynamic spectrum shape on the source parameters were studied in detail. In addition to simple periodic regimes, those with more complex spectral forms were found. In particular, alteration of spikes with different spectral shape can take place. It was also shown that quasi-stationary generation at the low-frequency band can coexist with periodic modulation at higher frequencies.

    On the basis of the results obtained, the model for explanation of

  3. Abrupt climate-independent fire regime changes

    Science.gov (United States)

    Pausas, Juli G.; Keeley, Jon E.

    2014-01-01

    Wildfires have played a determining role in distribution, composition and structure of many ecosystems worldwide and climatic changes are widely considered to be a major driver of future fire regime changes. However, forecasting future climatic change induced impacts on fire regimes will require a clearer understanding of other drivers of abrupt fire regime changes. Here, we focus on evidence from different environmental and temporal settings of fire regimes changes that are not directly attributed to climatic changes. We review key cases of these abrupt fire regime changes at different spatial and temporal scales, including those directly driven (i) by fauna, (ii) by invasive plant species, and (iii) by socio-economic and policy changes. All these drivers might generate non-linear effects of landscape changes in fuel structure; that is, they generate fuel changes that can cross thresholds of landscape continuity, and thus drastically change fire activity. Although climatic changes might contribute to some of these changes, there are also many instances that are not primarily linked to climatic shifts. Understanding the mechanism driving fire regime changes should contribute to our ability to better assess future fire regimes.

  4. Leverage effect, economic policy uncertainty and realized volatility with regime switching

    Science.gov (United States)

    Duan, Yinying; Chen, Wang; Zeng, Qing; Liu, Zhicao

    2018-03-01

    In this study, we first investigate the impacts of leverage effect and economic policy uncertainty (EPU) on future volatility in the framework of regime switching. Out-of-sample results show that the HAR-RV including the leverage effect and economic policy uncertainty with regimes can achieve higher forecast accuracy than RV-type and GARCH-class models. Our robustness results further imply that these factors in the framework of regime switching can substantially improve the HAR-RV's forecast performance.

  5. Instruments of RT-2 experiment onboard CORONAS-PHOTON and their test and evaluation III: Coded Aperture Mask and Fresnel Zone Plates in RT-2/CZT payload

    Science.gov (United States)

    Nandi, Anuj; Palit, S.; Debnath, D.; Chakrabarti, Sandip K.; Kotoch, T. B.; Sarkar, R.; Yadav, Vipin K.; Girish, V.; Rao, A. R.; Bhattacharya, D.

    2011-02-01

    Imaging in hard X-rays of any astrophysical source with high angular resolution is a challenging job. Shadow-casting technique is one of the most viable options for imaging in hard X-rays. We have used two different types of shadow-casters, namely, Coded Aperture Mask (CAM) and Fresnel Zone Plate (FZP) pair and two types of pixellated solid-state detectors, namely, CZT and CMOS in RT-2/CZT payload, the hard X-ray imaging instrument onboard the CORONAS-PHOTON satellite. In this paper, we present the results of simulations with different combinations of coders (CAM & FZP) and detectors that are employed in the RT-2/CZT payload. We discuss the possibility of detecting transient Solar flares with good angular resolution for various combinations. Simulated results are compared with laboratory experiments to verify the consistency of the designed configuration.

  6. Low-cost manufacturing of the point focus concentrating module and its key component, the Fresnel lens. Final subcontract report, 31 January 1991--6 May 1991

    Energy Technology Data Exchange (ETDEWEB)

    Saifee, T.; Konnerth, A. III [Solar Kinetics, Inc., Dallas, TX (United States)

    1991-11-01

    Solar Kinetics, Inc. (SKI) has been developing point-focus concentrating PV modules since 1986. SKI is currently in position to manufacture between 200 to 600 kilowatts annually of the current design by a combination of manual and semi-automated methods. This report reviews the current status of module manufacture and specifies the required approach to achieve a high-volume manufacturing capability and low cost. The approach taken will include process development concurrent with module design for automated manufacturing. The current effort reviews the major manufacturing costs and identifies components and processes whose improvements would produce the greatest effect on manufacturability and cost reduction. The Fresnel lens is one such key component. Investigating specific alternative manufacturing methods and sources has substantially reduced the lens costs and has exceeded the DOE cost-reduction goals. 15 refs.

  7. Framing of regimes and transition strategies

    DEFF Research Database (Denmark)

    Jensen, Jens Stissing

    2012-01-01

    This article suggests that transition strategies are always formulated in the context of specific representations of the regime and the challenges it faces. It is argued that the framing of a regime affects the envisioning of transition strategies. An analysis of the current development agenda fo...... for the housing construction sector in Denmark reveals the relevance and impacts of different regime framings. It is proposed that the ability to cope with framing issues as situated and political processes is at the core of the governance of transitions....

  8. Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling

    International Nuclear Information System (INIS)

    Mayer, Marcel; Keskinbora, Kahraman; Grévent, Corinne; Szeghalmi, Adriana; Knez, Mato; Weigand, Markus; Snigirev, Anatoly; Snigireva, Irina; Schütz, Gisela

    2013-01-01

    The fabrication and performance of multilayer Al 2 O 3 /Ta 2 O 5 Fresnel zone plates in the hard X-ray range and a discussion of possible future developments considering available materials are reported. Fresnel zone plates (FZPs) recently showed significant improvement by focusing soft X-rays down to ∼10 nm. In contrast to soft X-rays, generally a very high aspect ratio FZP is needed for efficient focusing of hard X-rays. Therefore, FZPs had limited success in the hard X-ray range owing to difficulties of manufacturing high-aspect-ratio zone plates using conventional techniques. Here, employing a method of fabrication based on atomic layer deposition (ALD) and focused ion beam (FIB) milling, FZPs with very high aspect ratios were prepared. Such multilayer FZPs with outermost zone widths of 10 and 35 nm and aspect ratios of up to 243 were tested for their focusing properties at 8 keV and shown to focus hard X-rays efficiently. This success was enabled by the outstanding layer quality thanks to ALD. Via the use of FIB for slicing the multilayer structures, desired aspect ratios could be obtained by precisely controlling the thickness. Experimental diffraction efficiencies of multilayer FZPs fabricated via this combination reached up to 15.58% at 8 keV. In addition, scanning transmission X-ray microscopy experiments at 1.5 keV were carried out using one of the multilayer FZPs and resolved a 60 nm feature size. Finally, the prospective of different material combinations with various outermost zone widths at 8 and 17 keV is discussed in the light of the coupled wave theory and the thin-grating approximation. Al 2 O 3 /Ir is outlined as a promising future material candidate for extremely high resolution with a theoretical efficiency of more than 20% for as small an outermost zone width as 10 nm at 17 keV

  9. Enhanced regime predictability in atmospheric low-order models due to stochastic forcing.

    Science.gov (United States)

    Kwasniok, Frank

    2014-06-28

    Regime predictability in atmospheric low-order models augmented with stochastic forcing is studied. Atmospheric regimes are identified as persistent or metastable states using a hidden Markov model analysis. A somewhat counterintuitive, coherence resonance-like effect is observed: regime predictability increases with increasing noise level up to an intermediate optimal value, before decreasing when further increasing the noise level. The enhanced regime predictability is due to increased persistence of the regimes. The effect is found in the Lorenz '63 model and a low-order model of barotropic flow over topography. The increased predictability is only present in the regime dynamics, that is, in a coarse-grained view of the system; predictability of individual trajectories decreases monotonically with increasing noise level. A possible explanation for the phenomenon is given and implications of the finding for weather and climate modelling and prediction are discussed. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  10. Sputtering of Ge(001): transition between dynamic scaling regimes

    DEFF Research Database (Denmark)

    Smilgies, D.-M.; Eng, P.J.; Landemark, E.

    1997-01-01

    We have studied the dynamic behavior of the Ge(001) surface during sputtering in situ and in real time using synchrotron X-ray diffraction. We find two dynamic regimes as a function of surface temperature and sputter current which are separated by a sharp transition. The boundary between these two...

  11. Effects of different irrigation regimes on vegetative growth, fruit yield ...

    African Journals Online (AJOL)

    This study was conducted during five growing seasons from 2004 to 2008 to investigate effects of different irrigation regimes on vegetative growth, fruit yield and quality of Salak apricot trees in semiarid climatic conditions. There were six irrigation treatments, five of which (S1, S2, S3, S4 and S5) were based on adjustment ...

  12. Spatial and temporal variation in a mesic savanna fire regime ...

    African Journals Online (AJOL)

    Umfolozi Park, a mesic savanna area in South Africa. The study focuses at the landscape scale of tens of kilometres and at the medium term temporal scale of decades. Variation in fire regime was analysed in relation to variation in annual rainfall ...

  13. Landscape level analysis of disturbance regimes in protected areas ...

    Indian Academy of Sciences (India)

    The present study has emphasized the moderate to low disturbance regimes in protected areas, which infer low biotic pressure and conservation effectiveness of PA network in Rajasthan. The spatial information generated on PAs is of valuable use for forest management and developing conservation strategies.

  14. Early signatures of regime shifts in complex dynamical systems

    Indian Academy of Sciences (India)

    2015-02-05

    Feb 5, 2015 ... Abstract. A large number of studies have recently been carried out on the early signatures of regime shifts in a number of dynamical systems, e.g., ecosystems, the climate, fish and wildlife populations, financial markets, complex diseases and gene circuits. The underlying model in most cases is that of the ...

  15. Revisiting democratic civil peace: Electoral regimes and civil conflict

    DEFF Research Database (Denmark)

    Bartusevicius, Henrikas; Skaaning, Svend-Erik

    2018-01-01

    The debate on democratic civil peace has centered on three general claims: democracies have a low risk of civil conflict, autocracies have the same low risk of conflict as democracies, and hybrid regimes have the highest conflict risk. We reevaluate these claims, emphasizing that previous studies...

  16. Regular and Chaotic Regimes in Scalar Field Cosmology

    Directory of Open Access Journals (Sweden)

    Alexey V. Toporensky

    2006-03-01

    Full Text Available A transient chaos in a closed FRW cosmological model with a scalar field is studied. We describe two different chaotic regimes and show that the type of chaos in this model depends on the scalar field potential. We have found also that for sufficiently steep potentials or for potentials with large cosmological constant the chaotic behavior disappears.

  17. Consumption, investment and life insurance under different tax regimes

    DEFF Research Database (Denmark)

    Bruun, Kenneth

    2013-01-01

    We study the effects of introducing taxation in classical continuous-time optimization problems with utility from consumption, bequest and retirement savings. Inspired by actual tax favoured retirement savings programs, we formulate and solve the optimization problem for various tax regimes, and ...

  18. Landscape level analysis of disturbance regimes in protected areas ...

    Indian Academy of Sciences (India)

    There is an urgent need to identify the human influence on landscape as disturbance regimes was realized for prioritization of the protected areas. The present study has attempted to describe the landscape level assessment of fragmentation and disturbance index in protected areas of Rajasthan using remote sensing and ...

  19. The CTBT regime, significance and potential benefits

    International Nuclear Information System (INIS)

    Chang, Hong-Lae

    2002-01-01

    This presentation briefly outlines the CTBT's background, describes the activities of the Preparatory Commission, the verification regime, the role of the National Data Centres and international coopereation. The objectives of the Nairobi workshop are listed

  20. The international climate regime: towards consolidation collapse

    International Nuclear Information System (INIS)

    Berthaud, P.; Cavard, D.; Criqui, P.

    2003-10-01

    This article deals with the different modalities that exist to manage a problem of collective action in the field of climate negotiation. It uses two concepts of the International Political Economy (IPE): the concept of International Regime (IR) and the concept of Hegemony and / or Leadership. The course the international negotiation has taken between 1992 (Rio Convention) and march 2001 (the US rejection of the Kyoto Protocol of 1997) leads us, first, to question the conditions of existence as well as the viability of a non-hegemonic International Regime (Part One). Then, we discuss the perspectives for the 'post - Kyoto' era. After having examined the preferences of the three most active actors in the negotiation (USA, Europe, G77 + China) combined with the leadership capacities they possess, we identify three scenarios for the future: i) anarchy, ii) an international regime under the American hegemony, iii) an international regime under the European leadership (Part Two). (author)

  1. Characteristics of radiated power for various TFTR [Tokamak Fusion Test Reactor] regimes

    International Nuclear Information System (INIS)

    Bush, C.E.; Schivell, J.; McNeill, D.H.

    1988-04-01

    Power loss studies were carried out to determine the impurity radiation and energy transport characteristics of various TFTR operation and confinement regimes including L-Mode, detached plasma, co-only neutral beam injection (energetic ion regime), and the enhanced confinement (''supershot'') regime. Combined bolometric, spectroscopic, and infrared photometry measurements provide a picture of impurity behavior and power accounting in TFTR. The purpose of this paper is to make a survey of the various regimes with the aim of determining the radiated power signatures of each. 10 refs., 6 figs., 1 tab

  2. Early signatures of regime shifts in gene expression dynamics

    International Nuclear Information System (INIS)

    Pal, Mainak; Pal, Amit Kumar; Ghosh, Sayantari; Bose, Indrani

    2013-01-01

    Recently, a large number of studies have been carried out on the early signatures of sudden regime shifts in systems as diverse as ecosystems, financial markets, population biology and complex diseases. The signatures of regime shifts in gene expression dynamics are less systematically investigated. In this paper, we consider sudden regime shifts in the gene expression dynamics described by a fold-bifurcation model involving bistability and hysteresis. We consider two alternative models, models 1 and 2, of competence development in the bacterial population B. subtilis and determine some early signatures of the regime shifts between competence and noncompetence. We use both deterministic and stochastic formalisms for the purpose of our study. The early signatures studied include the critical slowing down as a transition point is approached, rising variance and the lag-1 autocorrelation function, skewness and a ratio of two mean first passage times. Some of the signatures could provide the experimental basis for distinguishing between bistability and excitability as the correct mechanism for the development of competence. (paper)

  3. Authoritarian Regimes, Domestic Stability, and International Conflict

    OpenAIRE

    Bae, Joonbum

    2015-01-01

    This dissertation addresses the argument that there may not be room for cooperation in relations with (and in between) states with authoritarian systems of rule because international conflicts may strengthen their hold on power. To this end, it asks 1) whether authoritarian regimes benefit in terms of their duration in power from conflict, 2) whether conflicts stabilize domestic politics by moderating the violence involved during regime transitions (in terms of how they fall), and also 3) whe...

  4. Portfolio Selection with Jumps under Regime Switching

    Directory of Open Access Journals (Sweden)

    Lin Zhao

    2010-01-01

    Full Text Available We investigate a continuous-time version of the mean-variance portfolio selection model with jumps under regime switching. The portfolio selection is proposed and analyzed for a market consisting of one bank account and multiple stocks. The random regime switching is assumed to be independent of the underlying Brownian motion and jump processes. A Markov chain modulated diffusion formulation is employed to model the problem.

  5. Improving the taxation regime for electric power

    International Nuclear Information System (INIS)

    Fjermeros, Morten; Ilstad, Kristine

    2003-01-01

    In Norway, the present taxation regime for electric power is very complex. The power companies are currently charged with ordinary tax on profits, tax on economic rent, tax on natural resources and land tax. In addition there are the rules about licence fees, yield of power due to concession conditions, and reversion. The Norwegian Electricity Industry Association (EBL), assisted by a firm of lawyers, has proposed an improvement over the current taxation regime

  6. Brazil in the global anticorruption regime

    Directory of Open Access Journals (Sweden)

    Marcos Tourinho

    2018-03-01

    Full Text Available Abstract Brazilian anticorruption law and institutions were significantly transformed in recent decades. This article traces those transformations and explains how the international anticorruption and money laundering regimes contributed to their development. It argues that those international regimes were internalised in the Brazilian system through three mechanisms: inspiration and legitimation, coercion, and implementation support, and were critical to the transformation of Brazilian institutions.

  7. The Philippines: predatory regime, growing authoritarian features

    OpenAIRE

    Quimpo, Nathan Gilbert

    2009-01-01

    Over the past decade, and especially over the past few years, political corruption, fraud and violence in the Philippines have reached such alarming levels that many Filipinos have grown despondent, even cynical, about their country's political system. Exploring the suitability of the concepts of 'predatory state' and 'patrimonial oligarchic state' to the Philippines, I find that the regime rather than the state is the more appropriate unit of analysis. I argue that the predatory regime, cont...

  8. Analysis of the Two-Regime Method on Square Meshes

    KAUST Repository

    Flegg, Mark B.

    2014-01-01

    The two-regime method (TRM) has been recently developed for optimizing stochastic reaction-diffusion simulations [M. Flegg, J. Chapman, and R. Erban, J. Roy. Soc. Interface, 9 (2012), pp. 859-868]. It is a multiscale (hybrid) algorithm which uses stochastic reaction-diffusion models with different levels of detail in different parts of the computational domain. The coupling condition on the interface between different modeling regimes of the TRM was previously derived for onedimensional models. In this paper, the TRM is generalized to higher dimensional reaction-diffusion systems. Coupling Brownian dynamics models with compartment-based models on regular (square) two-dimensional lattices is studied in detail. In this case, the interface between different modeling regimes contains either flat parts or right-angle corners. Both cases are studied in the paper. For flat interfaces, it is shown that the one-dimensional theory can be used along the line perpendicular to the TRM interface. In the direction tangential to the interface, two choices of the TRM parameters are presented. Their applicability depends on the compartment size and the time step used in the molecular-based regime. The two-dimensional generalization of the TRM is also discussed in the case of corners. © 2014 Society for Industrial and Applied Mathematics.

  9. Politics, welfare regimes, and population health: controversies and evidence.

    Science.gov (United States)

    Muntaner, Carles; Borrell, Carme; Ng, Edwin; Chung, Haejoo; Espelt, Albert; Rodriguez-Sanz, Maica; Benach, Joan; O'Campo, Patricia

    2011-09-01

    In recent years, a research area has emerged within social determinants of health that examines the role of politics, expressed as political traditions/parties and welfare state characteristics, on population health. To better understand and synthesise this growing body of evidence, the present literature review, informed by a political economy of health and welfare regimes framework, located 73 empirical and comparative studies on politics and health, meeting our inclusion criteria in three databases: PubMed (1948-), Sociological Abstracts (1953-), and ISI Web of Science (1900-). We identified two major research programmes, welfare regimes and democracy, and two emerging programmes, political tradition and globalisation. Primary findings include: (1) left and egalitarian political traditions on population health are the most salutary, consistent, and substantial; (2) the health impacts of advanced and liberal democracies are also positive and large; (3) welfare regime studies, primarily conducted among wealthy countries, find that social democratic regimes tend to fare best with absolute health outcomes yet consistently in terms of relative health inequalities; and (4) globalisation defined as dependency indicators such as trade, foreign investment, and national debt is negatively associated with population health. We end by discussing epistemological, theoretical, and methodological issues for consideration for future research. © 2011 The Authors. Sociology of Health & Illness © 2011 Foundation for the Sociology of Health & Illness/Blackwell Publishing Ltd.

  10. Eurasian polities as hybrid regimes: The case of Putin's Russia

    Directory of Open Access Journals (Sweden)

    Henry E. Hale

    2010-01-01

    Full Text Available Most Eurasian countries' political systems are not accurately described as some version of either democracy or authoritarianism. Nor does it advance social science to study each of these countries' political systems as being completely unique, sharing no significant commonalities with those of other countries. Instead, it is more fruitful to understand many Eurasian countries as a type of hybrid regime, a system that combines important elements of both democracy and autocracy in some way. One of the most important features of Eurasia's hybrid regimes, one that is shared by many hybrid regimes worldwide, is that they combine contested elections with pervasive political clientelism. Political developments in these countries can thus be usefully understood as machine politics, and the development of political systems can be understood as processes of rearranging the components of the machines in different ways. The usefulness of this approach is demonstrated through an in-depth study of the Russian Federation. It is argued that Russian political development under Putin is best understood not as “authoritarianization” but as a process in which Russia transitioned from a system of “competing pyramids” of machine power to a “single-pyramid” system, a system dominated by one large political machine. It turns out that in single-pyramid systems that preserve contested elections, as does Russia, public opinion matters more than in typical authoritarian regimes.

  11. Wind regimes and their relation to synoptic variables using self-organizing maps

    Science.gov (United States)

    Berkovic, Sigalit

    2018-01-01

    This study exemplifies the ability of the self-organizing maps (SOM) method to directly define well known wind regimes over Israel during the entire year, except summer period, at 12:00 UTC. This procedure may be applied at other hours and is highly relevant to future automatic climatological analysis and applications. The investigation is performed by analysing surface wind measurements from 53 Israel Meteorological Service stations. The relation between the synoptic variables and the wind regimes is revealed from the averages of ECMWF ERA-INTERIM reanalysis variables for each SOM wind regime. The inspection of wind regimes and their average geopotential anomalies has shown that wind regimes relate to the gradient of the pressure anomalies, rather than to the specific isobars pattern. Two main wind regimes - strong western and the strong eastern or northern - are well known over this region. The frequencies of the regimes according to seasons is verified. Strong eastern regimes are dominant during winter, while strong western regimes are frequent in all seasons.

  12. Combined effects of rainfall regime and plot length on runoff and soil loss in the Loess Plateau of China

    Science.gov (United States)

    Liu, J.; Gao, G.; Wang, S.; Fu, B.

    2017-12-01

    The purpose of this paper was to study the interaction effects of rainfall regime and slope length on runoff and soil loss under different land uses. Event runoff and soil loss of forest, shrub and grass were measured in plots with length of 5, 9, or 13 m in the Loess Plateau from 2008 to 2016. Fifty-nine erosive rainfall events were recorded and classified into three rainfall regimes. The results firstly showed that the runoff coefficient was grass > shrub > forest, and soil loss was grass > forest > shrub, but the differences between forest and shrub in runoff and between grass and forest in soil loss didn't reach significant level. Secondly, rainfall regimes had important effect on runoff and soil loss of different land uses. The lowest runoff coefficients and the highest soil loss in regime 2 were found in shrub and forest land, respectively, which differed from that of regime 1. In total, rainfall regime 1 had the highest runoff coefficient of 0.84-2.06%, followed by regime 3 with 0.33-0.88%, and regime 2 with 0.04-0.06%. Soil loss in forest and grass land had a different order of regime 3 > regime 1 > regime 2. Thirdly, both the runoff coefficient and soil loss decreased with increasing plot length, while the effect of slope length on runoff/soil loss were influenced by land use type and rainfall regimes.

  13. Nature of exponents found in the critical regime of YBCO

    International Nuclear Information System (INIS)

    Marhas, Manmeet Kaur; Saravanan, P.; Balakrishnan, K.; Srinivasan, R.; Kanjilal, D.; Metha, G.K.; Pai, S.P.; Pinto, R.; Vedvyas, M.; Ogale, S.B.; Mohan Rao, G.; Nathan, Senthil; Mohan, S.

    1997-01-01

    Full text: Fluctuation effects in electrical conductivity near T c is an important tool for studying the nature of phase transition in high T c ceramics. Probing critical regime by way of experiments demand data of good precision. Measurements were carried out on well characterised high T c films prepared by laser ablation and high pressure oxygen sputtering. High energy ion irradiation carried out to see the effect of disorder. Precise electrical resistivity measurements were carried out near T c with a temperature control accuracy better than 10 mK and large number of data points were collected in this regime. 100 MeV oxygen and 200 MeV Ag ions were used with varying fluences for irradiation at 77K. The data was analysed using existing models of critical fluctuation effects. The exponent of electrical conductivity in laser ablated thin films whose transition widths are less than 1 K was 1.33 and is independent of disorder caused by high energy ion irradiation and this could be identified as the exponent for excess conductivity in the critical intermediate charged fluctuation regime as proposed by Fisher. The exponent is around 2.7 in those films whose transition widths are greater than 1 K and also was independent of disorder and this could be identified as exponent in the para coherence regime

  14. Predicting weather regime transitions in Northern Hemisphere datasets

    Energy Technology Data Exchange (ETDEWEB)

    Kondrashov, D. [University of California, Department of Atmospheric and Oceanic Sciences and Institute of Geophysics and Planetary Physics, Los Angeles, CA (United States); Shen, J. [UCLA, Department of Statistics, Los Angeles, CA (United States); Berk, R. [UCLA, Department of Statistics, Los Angeles, CA (United States); University of Pennsylvania, Department of Criminology, Philadelphia, PA (United States); D' Andrea, F.; Ghil, M. [Ecole Normale Superieure, Departement Terre-Atmosphere-Ocean and Laboratoire de Meteorologie Dynamique (CNRS and IPSL), Paris Cedex 05 (France)

    2007-10-15

    A statistical learning method called random forests is applied to the prediction of transitions between weather regimes of wintertime Northern Hemisphere (NH) atmospheric low-frequency variability. A dataset composed of 55 winters of NH 700-mb geopotential height anomalies is used in the present study. A mixture model finds that the three Gaussian components that were statistically significant in earlier work are robust; they are the Pacific-North American (PNA) regime, its approximate reverse (the reverse PNA, or RNA), and the blocked phase of the North Atlantic Oscillation (BNAO). The most significant and robust transitions in the Markov chain generated by these regimes are PNA {yields} BNAO, PNA {yields} RNA and BNAO {yields} PNA. The break of a regime and subsequent onset of another one is forecast for these three transitions. Taking the relative costs of false positives and false negatives into account, the random-forests method shows useful forecasting skill. The calculations are carried out in the phase space spanned by a few leading empirical orthogonal functions of dataset variability. Plots of estimated response functions to a given predictor confirm the crucial influence of the exit angle on a preferred transition path. This result points to the dynamic origin of the transitions. (orig.)

  15. Operating regimes of signaling cycles: statics, dynamics, and noise filtering.

    Directory of Open Access Journals (Sweden)

    Carlos Gomez-Uribe

    2007-12-01

    Full Text Available A ubiquitous building block of signaling pathways is a cycle of covalent modification (e.g., phosphorylation and dephosphorylation in MAPK cascades. Our paper explores the kind of information processing and filtering that can be accomplished by this simple biochemical circuit. Signaling cycles are particularly known for exhibiting a highly sigmoidal (ultrasensitive input-output characteristic in a certain steady-state regime. Here, we systematically study the cycle's steady-state behavior and its response to time-varying stimuli. We demonstrate that the cycle can actually operate in four different regimes, each with its specific input-output characteristics. These results are obtained using the total quasi-steady-state approximation, which is more generally valid than the typically used Michaelis-Menten approximation for enzymatic reactions. We invoke experimental data that suggest the possibility of signaling cycles operating in one of the new regimes. We then consider the cycle's dynamic behavior, which has so far been relatively neglected. We demonstrate that the intrinsic architecture of the cycles makes them act--in all four regimes--as tunable low-pass filters, filtering out high-frequency fluctuations or noise in signals and environmental cues. Moreover, the cutoff frequency can be adjusted by the cell. Numerical simulations show that our analytical results hold well even for noise of large amplitude. We suggest that noise filtering and tunability make signaling cycles versatile components of more elaborate cell-signaling pathways.

  16. Microgravity Flow Regime Data: Buoyancy and Mixing Apparatus Effects

    Science.gov (United States)

    Shephard, Adam; Best, Frederick

    2010-01-01

    Zero-g two-phase flow data set qualification and flight experiment design have not been standardized and as a result, agreement among researchers has not been reached regarding what experimental conditions adequately approximate those of microgravity. The effects of buoyancy forces and mixing apparatus on the flow regime transitions are presented in this study. The gravity conditions onboard zero-g aircraft are at best 10-3 g which is used to approximate the 10-5 g conditions of microgravity, thus the buoyancy forces present on zero-g aircraft can become significantly large and unrepresentative of microgravity. When buoyancy forces approach those of surface tension forces, buoyancy induced coalescence occurs. When discussing flow regime transitions, these large buoyancy forces lead to flow regime transitions which otherwise would not occur. The buoyancy attributes of the two-phase flow data sets available in the literature are evaluated to determine which data sets exhibit buoyancy induced transitions. Upon comparison of the representative data sets, the affects of different mixing apparatus can be seen in the superficial velocity flow regime maps.

  17. Body size distributions signal a regime shift in a lake ...

    Science.gov (United States)

    Communities of organisms, from mammals to microorganisms, have discontinuous distributions of body size. This pattern of size structuring is a conservative trait of community organization and is a product of processes that occur at multiple spatial and temporal scales. In this study, we assessed whether body size patterns serve as an indicator of a threshold between alternative regimes. Over the past 7000 years, the biological communities of Foy Lake (Montana,USA) have undergone a major regime shift owing to climate change. We used a palaeoecological record of diatom communities to estimate diatom sizes, and then analysed the discontinuous distribution of organism sizes over time. We used Bayesian classification and regression tree models to determine that all time intervals exhibited aggregations of sizes separated by gaps in the distribution and found a significant change in diatom body size distributions approximately 150 years before the identified ecosystem regime shift. We suggest that discontinuity analysis is a useful addition to the suite of tools for the detection of early warning signals of regime shifts. Communities of organisms from mammals to microorganisms have discontinuous distributions of body size. This pattern of size structuring is a conservative trait of community organization and is a product of processes that occur at discrete spatial and temporal scales within ecosystems. Here, a paleoecological record of diatom community change is use

  18. A2AR Binding Kinetics in the Ligand Depletion Regime.

    Science.gov (United States)

    McNeely, Patrick M; Naranjo, Andrea N; Forsten-Williams, Kimberly; Robinson, Anne Skaja

    2017-02-01

    Ligand binding plays a fundamental role in stimulating the downstream signaling of membrane receptors. Here, ligand-binding kinetics of the full-length human adenosine A 2A receptor (A 2A R) reconstituted in detergent micelles were measured using a fluorescently labeled ligand via fluorescence anisotropy. Importantly, to optimize the signal-to-noise ratio, these experiments were conducted in the ligand depletion regime. In the ligand depletion regime, the assumptions used to determine analytical solutions for one-site binding models for either one or two ligands in competition are no longer valid. We therefore implemented a numerical solution approach to analyze kinetic binding data as experimental conditions approach the ligand depletion regime. By comparing the results from the numerical and the analytical solutions, we highlight the ligand-receptor ratios at which the analytical solution begins to lose predictive accuracy. Using the numerical solution approach, we determined the kinetic rate constants of the fluorescent ligand, FITC-APEC, and those for three unlabeled ligands using competitive association experiments. The association and dissociation rate constants of the unlabeled ligands determined from the competitive association experiments were then independently validated using competitive dissociation data. Based on this study, a numerical solution is recommended to determine kinetic ligand-binding parameters for experiments conducted in the ligand-depletion regime.

  19. The perturbative Regge-calculus regime of loop quantum gravity

    International Nuclear Information System (INIS)

    Bianchi, Eugenio; Modesto, Leonardo

    2008-01-01

    The relation between loop quantum gravity and Regge calculus has been pointed out many times in the literature. In particular the large spin asymptotics of the Barrett-Crane vertex amplitude is known to be related to the Regge action. In this paper we study a semiclassical regime of loop quantum gravity and show that it admits an effective description in terms of perturbative area-Regge-calculus. The regime of interest is identified by a class of states given by superpositions of four-valent spin networks, peaked on large spins. As a probe of the dynamics in this regime, we compute explicitly two- and three-area correlation functions at the vertex amplitude level. We find that they match with the ones computed perturbatively in area-Regge-calculus with a single 4-simplex, once a specific perturbative action and measure have been chosen in the Regge-calculus path integral. Correlations of other geometric operators and the existence of this regime for other models for the dynamics are briefly discussed

  20. Operating regimes of signaling cycles: statics, dynamics, and noise filtering.

    Science.gov (United States)

    Gomez-Uribe, Carlos; Verghese, George C; Mirny, Leonid A

    2007-12-01

    A ubiquitous building block of signaling pathways is a cycle of covalent modification (e.g., phosphorylation and dephosphorylation in MAPK cascades). Our paper explores the kind of information processing and filtering that can be accomplished by this simple biochemical circuit. Signaling cycles are particularly known for exhibiting a highly sigmoidal (ultrasensitive) input-output characteristic in a certain steady-state regime. Here, we systematically study the cycle's steady-state behavior and its response to time-varying stimuli. We demonstrate that the cycle can actually operate in four different regimes, each with its specific input-output characteristics. These results are obtained using the total quasi-steady-state approximation, which is more generally valid than the typically used Michaelis-Menten approximation for enzymatic reactions. We invoke experimental data that suggest the possibility of signaling cycles operating in one of the new regimes. We then consider the cycle's dynamic behavior, which has so far been relatively neglected. We demonstrate that the intrinsic architecture of the cycles makes them act--in all four regimes--as tunable low-pass filters, filtering out high-frequency fluctuations or noise in signals and environmental cues. Moreover, the cutoff frequency can be adjusted by the cell. Numerical simulations show that our analytical results hold well even for noise of large amplitude. We suggest that noise filtering and tunability make signaling cycles versatile components of more elaborate cell-signaling pathways.

  1. The climate space of fire regimes in north-western North America

    Science.gov (United States)

    Whitman, Ellen; Batllori, Enric; Parisien, Marc-André; Miller, Carol; Coop, Jonathan D.; Krawchuk, Meg A.; Chong, Geneva W.; Haire, Sandra L.

    2015-01-01

    Aim. Studies of fire activity along environmental gradients have been undertaken, but the results of such studies have yet to be integrated with fire-regime analysis. We characterize fire-regime components along climate gradients and a gradient of human influence. Location. We focus on a climatically diverse region of north-western North America extending from northern British Columbia, Canada, to northern Utah and Colorado, USA.Methods. We used a multivariate framework to collapse 12 climatic variables into two major climate gradients and binned them into 73 discrete climate domains. We examined variation in fire-regime components (frequency, size, severity, seasonality and cause) across climate domains. Fire-regime attributes were compiled from existing databases and Landsat imagery for 1897 large fires. Relationships among the fire-regime components, climate gradients and human influence were examined through bivariate regressions. The unique contribution of human influence was also assessed.Results. A primary climate gradient of temperature and summer precipitation and a secondary gradient of continentality and winter precipitation in the study area were identified. Fire occupied a distinct central region of such climate space, within which fire-regime components varied considerably. We identified significant interrelations between fire-regime components of fire size, frequency, burn severity and cause. The influence of humans was apparent in patterns of burn severity and ignition cause.Main conclusions. Wildfire activity is highest where thermal and moisture gradients converge to promote fuel production, flammability and ignitions. Having linked fire-regime components to large-scale climate gradients, we show that fire regimes – like the climate that controls them – are a part of a continuum, expanding on models of varying constraints on fire activity. The observed relationships between fire-regime components, together with the distinct role of climatic

  2. When can refuges mediate the genetic effects of fire regimes? A simulation study of the effects of topography and weather on neutral and adaptive genetic diversity in fire-prone landscapes.

    Science.gov (United States)

    Banks, Sam C; Davies, Ian D; Cary, Geoffrey J

    2017-10-01

    Understanding how landscape heterogeneity mediates the effects of fire on biodiversity is increasingly important under global changes in fire regimes. We used a simulation experiment to investigate how fire regimes interact with topography and weather to shape neutral and selection-driven genetic diversity under alternative dispersal scenarios, and to explore the conditions under which microrefuges can maintain genetic diversity of populations exposed to recurrent fire. Spatial heterogeneity in simulated fire frequency occurred in topographically complex landscapes, with fire refuges and fire-prone "hotspots" apparent. Interannual weather variability reduced the effect of topography on fire patterns, with refuges less apparent under high weather variability. Neutral genetic diversity was correlated with long-term fire frequency under spatially heterogeneous fire regimes, being higher in fire refuges than fire-prone areas, except under high dispersal or low fire severity (low mortality). This generated different spatial genetic structures in fire-prone and fire-refuge components of the landscape, despite similar dispersal. In contrast, genetic diversity was only associated with time since the most recent fire in flat landscapes without predictable refuges and hotspots. Genetic effects of selection driven by fire-related conditions depended on selection pressure, migration distance and spatial heterogeneity in fire regimes. Allele frequencies at a locus conferring higher fitness under successional environmental conditions followed a pattern of "temporal adaptation" to contemporary conditions under strong selection pressure and high migration. However, selected allele frequencies were correlated with spatial variation in long-term mean fire frequency (relating to environmental predictability) under weak dispersal, low selection pressure and strong spatial heterogeneity in fire regimes. © 2017 John Wiley & Sons Ltd.

  3. National Transparency Regimes : Rules or Principles? A Comparative Analysis of the United States and The Netherlands

    NARCIS (Netherlands)

    Ruijer, Erna; Meijer, Albert

    2016-01-01

    Technology development and democratization have been identified as the general drivers of the worldwide thrust in transparency. But what transparency regimes do these drivers generate in different countries? This mixed method study indicates that national regimes are different due to pre-existing

  4. Highlighting the retro side of innovation and its potential for regime change in agriculture

    NARCIS (Netherlands)

    Stuiver, M.

    2006-01-01

    The potential impact of farmer's innovations for the development of food regimes is the topic of this chapter. Two case studies analysed from the perspective of strategic niche management show that there is niche formation visible as an alternative to the dominant modern food regime. These

  5. Crafting Innovations : the evolving institutional regimes of handicraft exporters in emerging economies

    NARCIS (Netherlands)

    J. Fransen (Jan)

    2016-01-01

    markdownabstractThe objective of this study is to identify how evolving institutional regimes explain incremental innovation of craft exporters in emerging economies. Institutional regimes are sets of similarly featured rules, and the actors that produce and reproduce them. The handicraft

  6. Fire regimes and variability in aboveground woody biomass in miombo woodland

    NARCIS (Netherlands)

    Saito, Makoto; Luyssaert, Sebastiaan; Poulter, Ben; Williams, Mathew; Ciais, Philippe; Bellassen, Valentin; Ryan, Casey M.; Yue, Chao; Cadule, Patricia; Peylin, Philippe

    2014-01-01

    This study combined a process-based ecosystem model with a fire regime model to understand the effect of changes in fire regime and climate pattern on woody plants of miombo woodland in African savanna. Miombo woodland covers wide areas in Africa and is subject to frequent anthropogenic fires. The

  7. On spinfoam models in large spin regime

    International Nuclear Information System (INIS)

    Han, Muxin

    2014-01-01

    We study the semiclassical behavior of Lorentzian Engle–Pereira–Rovelli–Livine (EPRL) spinfoam model, by taking into account the sum over spins in the large spin regime. We also employ the method of stationary phase analysis with parameters and the so-called, almost analytic machinery, in order to find the asymptotic behavior of the contributions from all possible large spin configurations in the spinfoam model. The spins contributing the sum are written as J f = λj f , where λ is a large parameter resulting in an asymptotic expansion via stationary phase approximation. The analysis shows that at least for the simplicial Lorentzian geometries (as spinfoam critical configurations), they contribute the leading order approximation of spinfoam amplitude only when their deficit angles satisfy γ Θ-ring f ≤λ −1/2 mod 4πZ. Our analysis results in a curvature expansion of the semiclassical low energy effective action from the spinfoam model, where the UV modifications of Einstein gravity appear as subleading high-curvature corrections. (paper)

  8. The TR method: the use of slip preference to separate heterogeneous fault-slip data in compressional stress regimes. The surface rupture of the 1999 Chi-Chi Taiwan earthquake as a case study

    Science.gov (United States)

    Tranos, Markos D.

    2013-11-01

    Synthetic contractional fault-slip data have been considered in order to examine the validity of widely applied criteria such as the slip preference, slip tendency, kinematic (P and T) axes, transport orientation and strain compatibility in different Andersonian compressional stress regimes. Radial compression (RC), radial-pure compression (RC-PC), pure compression (PC), pure compression-transpression (PC-TRP), and transpression (TRP) are examined with the aid of the Win-Tensor stress inversion software. Furthermore, the validity of the recently proposed graphical TR method, which uses the concept of slip preference for the separation of heterogeneous fault-slip data, is also examined for compressional stress regimes. In these regimes only contractional faults can be activated, and their slip preferences imply the distinction between “real”, i.e., RC, RC-PC and PC, and “hybrid”, i.e., PC-TRP and TRP stress regimes. For slip tendency values larger than 0.6, the activated faults dip at angles from 10° to 50°, but in the “hybrid” regimes faults can dip with even higher angles. The application of the TR method is here refined by introducing two controlling parameters, the coefficient of determination (R2) of the Final Tensor Ratio Line (FTRL) and the “normal” or “inverse” distribution of the faults plotted within the Final Tensor Ratio Belt (FTRB). The application of the TR method on fault-slip data of the 1999 Chi-Chi earthquake, Taiwan, allowed the meaningful separation of complex heterogeneous contractional fault-slip data into homogeneous groups. In turn, this allowed the identification of different compressional stress regimes and the determination of local stress perturbations of the regional or far-stress field generated by the 1999 Chi-Chi earthquake. This includes clear examples of “stress permutation” and “stress partitioning” caused by pre-existing fault structures, such as the N-S trending Chelungpu thrust and the NE

  9. Progress towards a global nuclear liability regime

    International Nuclear Information System (INIS)

    2014-01-01

    During its April 2014 meeting, the Steering Committee for Nuclear Energy held a policy debate on 'Progress towards a Global Nuclear Liability Regime'. The Steering Committee heard presentations from several experts on nuclear liability issues. To prepare the delegates to the Steering Committee for the policy debate, the NEA Secretariat prepared a background note on the status of the nuclear liability regimes, as well as on current issues and challenges in implementing the regimes. This article is based on the background note and is intended to provide basic information on the relevant international conventions and an overview of recent developments to enhance the understanding of the legal framework in which policy-makers and practitioners are engaging to respond to the call for broader adherence to the international liability instruments. (authors)

  10. Multiscale regime shifts and planetary boundaries.

    Science.gov (United States)

    Hughes, Terry P; Carpenter, Stephen; Rockström, Johan; Scheffer, Marten; Walker, Brian

    2013-07-01

    Life on Earth has repeatedly displayed abrupt and massive changes in the past, and there is no reason to expect that comparable planetary-scale regime shifts will not continue in the future. Different lines of evidence indicate that regime shifts occur when the climate or biosphere transgresses a tipping point. Whether human activities will trigger such a global event in the near future is uncertain, due to critical knowledge gaps. In particular, we lack understanding of how regime shifts propagate across scales, and whether local or regional tipping points can lead to global transitions. The ongoing disruption of ecosystems and climate, combined with unprecedented breakdown of isolation by human migration and trade, highlights the need to operate within safe planetary boundaries. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Causas estruturais e consequências dos regimes internacionais: regimes como variáveis intervenientes

    Directory of Open Access Journals (Sweden)

    Stephen D. Krasner

    2012-06-01

    Full Text Available Os regimes internacionais são definidos como princípios, normas, regras e procedimentos de tomada de decisões ao redor dos quais as expectativas dos atores convergem em uma dada área-tema. Como ponto de partida, os regimes são conceituados como variáveis intervenientes, estando entre fatores causais básicos e os resultados e comportamentos relacionados. Há três visões a respeito da importância dos regimes: as orientações estruturais convencionais desvalorizam os regimes como sendo, na melhor das hipóteses, ineficazes; as orientações grocianas vêem os regimes como componentes íntimos do sistema internacional; as perspectivas estruturalistas modificadas vêem os regimes como significativos somente em certas condições restritas. Para os argumentos grociano e estruturalista modificado - que concordam com a visão de que os regimes podem influenciar resultados e comportamentos - , o desenvolvimento de regimes é visto como uma função de cinco variáveis causais básicas: auto-interesse egoísta; poder político; normas e princípios difusos; usos e costumes; conhecimento.

  12. Fire regimes during the last glacial

    Science.gov (United States)

    Daniau, A.; Harrison, S. P.; Bartlein, P. J.

    2009-12-01

    Fire regimes during the last glacial A.-L. Daniau (1), S.P. Harrison (1) and P.J. Bartlein (2) (1) School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UK (2) Department of Geography, University of Oregon, Eugene, OR 97403, USA Sedimentary charcoal records document changes in fire regime. We have identified 67 sites which have records for some part of the last glacial and have used the 30 of these sites with better-than millennial-resolution to analyse changes in global fire regimes. Fire was consistently lower during the glacial than during the Eemian and Holocene. Within the glacial, Marine Isotope Stage (MIS) 3 is characterised globally by more fire than MIS 2. The signal for MIS 4 is less clear: there is more fire in the northern hemisphere and less fire in the southern hemisphere than during MIS 2 and 3. The records, most particularly records from the northern extratropics, show millennial-scale variability in fire regimes corresponding to the rapid climate changes associated with Dansgaard-Oeschger (D-O) cycles. Most of the D-O cycles during the last glacial and all of the Heinrich Stadials are apparent in the composite global record of the high-resolution sites: fire increases during D-O warming events and decreases during intervals of cooling. Our analyses show that fire regimes show a lagged response to rapid climate changes of ca 100-200 years in the case of D-O warming events, ca 0-100 years in the case of D-O cooling events and ca 200 years in the case of Heinrich Stadials. The strong climatic variability experienced during the glacial resulted in important changes in fire regimes even though the base level of biomass burning was less than today.

  13. The seismology of geothermal regimes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Aki, K.

    1997-04-01

    The authors have been developing seismological interpretation theory and methods applicable to complex structures encountered in geothermal areas for a better understanding of the earth`s geothermal regimes. The questions the y have addressed in their research may be summarized as ``What is going on in the earth`s crust under tectonically active regions; what are the structures and processes responsible for such activities as earthquakes and volcanic eruptions; and how can one capture their essence effectively by means of seismological studies?`` First, the authors found clear evidence for localization of scattered seismic energy in the deep magmatic system of the volcano on the island of Reunion in the Indian Ocean. The seismic coda of local earthquakes show concentrated energy in the intrusive zones as late as 30 to 40 seconds after the origin time. This offers a very effective method for defining a zone of strong heterogeneity on a regional scale, complementary to the high resolution study using trapped modes as pursued in the past project. Secondly, the authors identified about 700 long-period events with various frequencies and durations from the data collected during the past 5 years which included three episodes of eruption. They are applying a finite-element method to the simplest event with the longest period and the shortest duration in order to find the location, geometry and physical properties of their source deterministically. The preliminary result described here suggests that their sources may be a horizontally lying magma-filled crack at a shallow depth under the summit area. In addition to the above work on the Reunion data, they have continued the theoretical and observational studies of attenuation and scattering of seismic waves.

  14. WELFARE REGIMES IN LATIN AMERICA AND CARIBBEAN

    Directory of Open Access Journals (Sweden)

    Melisa Campana-Alabarce

    2015-06-01

    Full Text Available This article provides a characterization of Latin American and Caribbean Welfare regimes in historiographical perspective. Firstly, it makes a review of the emergence conditions of Welfare States in Western Europe and its core features, with particular emphasis on its role as a method to regulate inequalities in industrial capitalism. Dialoguing with it, then stops in the specific configurations that welfare regimes have taken in Latin America during the course of the twentieth century. Finally, it provides a map of its contemporary features and the major challenges that the States of the region face in his capacity as right guarantors for the future.

  15. The oil tax regime of Azerbaijan

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Gerard

    1998-07-01

    Azerbaijan has a long history in the oil business and a chance of a spectacular future. To understand why the oil tax regime evolved into its present form and how it is likely to develop, it is necessary to know something of the country's history and the commercial environment. Consequently the presentation begins by discussing these items. It then outlines the Production Sharing Agreement regime in Azerbaijan and then deals with the Kazakh and Georgian Tax Codes, as these are likely to be the basis of a new general tax law in Azerbaijan from 1999. The presentation includes comments on the New Draft Tax Code of 1998.

  16. Legal Regimes of Official Information in Ukraine

    Directory of Open Access Journals (Sweden)

    Serhii Yesimov

    2018-04-01

    Full Text Available In the article on the basis of the methodology of system analysis the legal nature and sources of legal regulation of the legal regime of official information in Ukraine in the conditions of adaptation of Ukrainian legislation to the legislation of the European Union are considered. A comparative legal analysis of official information in the public-law and private-law spheres in the context of legal regimes of restricted information, confidential information and information classified as state secrets has been conducted.

  17. Towards a Global Regime of Higher Education

    Directory of Open Access Journals (Sweden)

    Paolo Do

    2015-12-01

    Full Text Available This paper rethinks the spatialization of educational institutions at the global level, scaling and rescaling the space of the university as an inclusive process that makes academic knowledge production something heterogeneous, complex and composite, and proposing a regime for the higher education system based on a stratified relationship that is asymmetrical and geographically displaced. Moreover it outlines the “new” political economy of knowledge, which is a particular mechanism in contemporary capitalist production, capable of creating an artificial scarcity of knowledge by means of hierarchies, and reproducing the classical law of value in a regime based on abundance instead of scarcity.

  18. Statistics of exchange rate regimes in Nigeria | Iwueze | Global ...

    African Journals Online (AJOL)

    The three distinct exchange rate regimes of Nigeria were subjected to Autoregressive Integrated Moving Average (ARIMA) modeling in order to compare them with respect to model structure. It was found that the three regimes admit different models. Regime one admits Moving average model of order 2, Regime two admits ...

  19. Oral health and welfare state regimes: a cross-national analysis of European countries.

    Science.gov (United States)

    Guarnizo-Herreño, Carol C; Tsakos, Georgios; Sheiham, Aubrey; Watt, Richard G

    2013-06-01

    Very little is known about the potential relationship between welfare state regimes and oral health. This study assessed the oral health of adults in a range of European countries clustered by welfare regimes according to Ferrera's typology and the complementary Eastern type. We analysed data from Eurobarometer wave 72.3, a cross-sectional survey of 31 European countries carried out in 2009. We evaluated three self-reported oral health outcomes: edentulousness, no functional dentition (welfare state regime. The Scandinavian regime showed lower prevalence rates for all outcomes. For edentulousness and no functional dentition, there were higher prevalence rates in the Eastern regime but no significant differences between Anglo-Saxon, Bismarckian, and Southern regimes. The Southern regime presented a higher prevalence of oral impacts on daily living. Results by country indicated that Sweden had the lowest prevalences for edentulousness and no functional dentition, and Denmark had the lowest prevalence for oral impacts. The results suggest that Scandinavian welfare states, with more redistributive and universal welfare policies, had better population oral health. Future research should provide further insights about the potential mechanisms through which welfare-state regimes would influence oral health. © 2013 Eur J Oral Sci.

  20. Density and spin modes in imbalanced normal Fermi gases from collisionless to hydrodynamic regime

    Science.gov (United States)

    Narushima, Masato; Watabe, Shohei; Nikuni, Tetsuro

    2018-03-01

    We study the mass- and population-imbalance effect on density (in-phase) and spin (out-of-phase) collective modes in a two-component normal Fermi gas. By calculating the eigenmodes of the linearized Boltzmann equation as well as the density/spin dynamic structure factor, we show that mass- and population-imbalance effects offer a variety of collective mode crossover behaviors from collisionless to hydrodynamic regimes. The mass-imbalance effect shifts the crossover regime to the higher-temperature, and a significant peak of the spin dynamic structure factor emerges only in the collisionless regime. This is in contrast to the case of mass- and population-balanced normal Fermi gases, where the spin dynamic response is always absent. Although the population-imbalance effect does not shift the crossover regime, the spin dynamic structure factor survives both in the collisionless and hydrodynamic regimes.

  1. An emissions trading regime for Canada

    International Nuclear Information System (INIS)

    Smith, S.L.

    2001-01-01

    In 1998, over twelve papers were published on emissions trading regimes in Canada by the National Round Table on the Environment and the Economy (NRTEE), a federal government agency whose members represent stakeholders as varied as business, environmental groups, academics, aboriginal groups and others. One of the recommendations that emerged was for the computer modelling of the possibilities that had been identified for a domestic trading regime in Canada for greenhouse gases. It is unclear whether the modelling was ever performed as the file was taken over by the Finance Department under the umbrella of a special emission trading table that examined Canada's commitment under the Kyoto Protocol. The author examined questions pertaining to whether a domestic trading regime is essential, and what its characteristics should be in case it was deemed essential or advisable to have one. The upstream versus downstream application was looked at, as well as grand-fathering versus auction. Provincial issues were then addressed, followed by meshing with a credit system. International systems were reviewed. Early action was discussed, whereby an emitter seeks credit for action taken toward reductions since the original reference year of 1990. The case of emitters having bought or sold permits since the original reference years will also want those trades recognized under a trading regime. The author indicated that it seems probable that an emission trading system will eventually be implemented and that a debate on the issue should be initiated early

  2. Comprehensive review of the maritime safety regimes.

    NARCIS (Netherlands)

    S. Knapp (Sabine); Ph.H.B.F. Franses (Philip Hans)

    2007-01-01

    textabstractThis report presents a comprehensive review of the maritime safety regimes and provides recommendations on how to improve the system. The results show a complex legal framework which generates a high amount of inspections and overlapping of inspection areas where no cross-recognition is

  3. Radiative effects of global MODIS cloud regimes

    Science.gov (United States)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin; Kato, Seiji

    2018-01-01

    We update previously published MODIS global cloud regimes (CRs) using the latest MODIS cloud retrievals in the Collection 6 dataset. We implement a slightly different derivation method, investigate the composition of the regimes, and then proceed to examine several aspects of CR radiative appearance with the aid of various radiative flux datasets. Our results clearly show the CRs are radiatively distinct in terms of shortwave, longwave and their combined (total) cloud radiative effect. We show that we can clearly distinguish regimes based on whether they radiatively cool or warm the atmosphere, and thanks to radiative heating profiles to discern the vertical distribution of cooling and warming. Terra and Aqua comparisons provide information about the degree to which morning and afternoon occurrences of regimes affect the symmetry of CR radiative contribution. We examine how the radiative discrepancies among multiple irradiance datasets suffering from imperfect spatiotemporal matching depend on CR, and whether they are therefore related to the complexity of cloud structure, its interpretation by different observational systems, and its subsequent representation in radiative transfer calculations. PMID:29619289

  4. Stochastic dynamical models for ecological regime shifts

    DEFF Research Database (Denmark)

    Møller, Jan Kloppenborg; Carstensen, Jacob; Madsen, Henrik

    phytoplankton and benthic vegetation with feedback mechanisms is formulated, and it is demonstrated that bistability can occur for specific parameter settings. When stochastic input and stochastic propagation of the states are applied on the system regime shifts occur more frequently, and the threshold...

  5. European welfare regimes: Political orientations versus poverty

    Directory of Open Access Journals (Sweden)

    Josifidis Kosta

    2011-01-01

    Full Text Available This inquiry analyzes how political orientations shape welfare states and labour market institutions when seeking to reduce poverty. In order to identify effects of these two key variables, we conduct a panel regression analysis that includes two poverty measures: poverty rates before and after social spending. This inquiry considers 14 EU countries, and in the period from 1995 to 2008, which are grouped according to welfare state regimes. We consider Social Democratic, Corporatist, Mediterranean and Liberal welfare state regimes. Panel regression results indicate that political orientation engenders no significant statistically measurable effects on poverty rates before social spending. Effects register, however, as significant when considering poverty rates after social spending. With respect to the first set of results, we advance two key explanations. First, we note a longer period of time is necessary in order to observe actual effects of political orientation on market generated poverty. Second, political parties with their respective programs do not register as influential enough to solve social problems related to income distribution when taken alone. Influences register as indirect and are expressed through changes in employment rates and social spending. The second set of results support the hypothesis that a selected political regime does indeed contribute to poverty reduction. In sum, political orientation and political regime does indeed affect poverty through welfare state institutions, as well as through labour market institutions.

  6. Estimation in autoregressive models with Markov regime

    OpenAIRE

    Ríos, Ricardo; Rodríguez, Luis

    2005-01-01

    In this paper we derive the consistency of the penalized likelihood method for the number state of the hidden Markov chain in autoregressive models with Markov regimen. Using a SAEM type algorithm to estimate the models parameters. We test the null hypothesis of hidden Markov Model against an autoregressive process with Markov regime.

  7. EARLY INTERVENTION REGIME UNDER THE BANK ...

    African Journals Online (AJOL)

    OLAWUYI

    2000-03-01

    Mar 1, 2000 ... consumption and investment plans; allocating the savings of households and businesses to ... World Bank Principles and Guidelines for Effective Insolvency and Creditor Rights Systems, IMF's ... February 2009 addressed the immediate need for a special bank resolution regime following the global.

  8. A Comparative Typology of Pension Regimes

    NARCIS (Netherlands)

    Arjan Soede; Cok Vrooman

    2008-01-01

    This report presents an empirical typology of pension regimes in the European Union, the US, Canada, Australia and Norway. The categorisation is based on 34 quantitative and qualitative characteristics of the mandatory parts of the pension systems in these countries. The empirical analysis shows

  9. Yukon's common oil and gas regime

    International Nuclear Information System (INIS)

    Love, B.

    1998-01-01

    The Yukon's common oil and gas regime was developed in partnership with First Nations and it sets out the rules that will apply throughout the Yukon and on Yukon and First Nation lands. While separate and distinct, it conforms with and is compatible with other government systems and regimes. The major elements of the common regime include the Oil and Gas Act, regulations, policies, processes and agreements. The specific opportunities that are available in each phase of oil and gas development in the Yukon are described, with a map showing all basins, reserves and sites of current oil and gas activity. The Yukon has eight potential oil and gas basins: North Coast, Old Crow, Kandik, Eagle Plain, Peel Plateau, Bonnet Plume, Whitehorse Trough, and Liard Plateau. Only three of the eight, the Liard Plateau, Whitehorse Trough and Eagle Plain, have been explored. No wells have been drilled in several of Yukon's basins. Factors influencing economic opportunities in the Territory are also described, including: (1) international events and energy markets, (2) North American gas markets, (3) environmental factors, (4) competitiveness of the Yukon regime, and (5) the commitment of industry resources. 4 figs

  10. The Forex Regime and EMU Expansion

    NARCIS (Netherlands)

    P.W. van Foreest; C.G. de Vries (Casper)

    2002-01-01

    textabstractThis paper provides empirical evidence that, irrespective of the foreign exchange rate regime, countries with high monetary volatility have lower relative output growth rates. It is argued that due to the forward looking nature of the foreign exchange market, exchange rate stability

  11. Early detection of ecosystem regime shifts

    DEFF Research Database (Denmark)

    Lindegren, Martin; Dakos, Vasilis; Groeger, Joachim P.

    2012-01-01

    Critical transitions between alternative stable states have been shown to occur across an array of complex systems. While our ability to identify abrupt regime shifts in natural ecosystems has improved, detection of potential early-warning signals previous to such shifts is still very limited. Us...

  12. [The "specific" liability regime for blood products].

    Science.gov (United States)

    Byk, Christian

    2017-10-13

    Based on the system of liability for defective products as organized by the European Directive of 25 July 1985, responsibility for blood products does not therefore constitute a genuine specific regime. However, European law leaves States a margin of discretion in the implementation of the Directive with regard to health products. This is the case in particular with the exemption for development risk.

  13. STATISTICS OF EXCHANGE RATE REGIMES IN NIGERIA

    African Journals Online (AJOL)

    DJFLEX

    2009-02-11

    Feb 11, 2009 ... KEY WORDS: Exchange Rate Regime; ARIMA Model, Stationarity, Random Walk Model. INTRODUCTION. Exchange rate has been defined as the price of one currency in terms of another. It can be expressed in one of two ways: as units of domestic currency per unit of foreign currency; or units of foreign ...

  14. Searching for an Appropriate Exchange Rate Regime

    Directory of Open Access Journals (Sweden)

    Yunjong Wang

    2001-06-01

    Full Text Available This paper attempts to survey current debates on the choice of exchange rate regime in emerging market economies. The issue of choosing an appropriate exchange rate regime is being actively discussed since the recent Asian crisis. As a lesson from the recent crises, one widely shared conclusion is that soft peg exchange rate regimes are extremely vulnerable in a world of volatile capital movements. Consequently, new orthodoxy based on the impossible trinity hypothesis favours two corner solutions ― greater flexibility or credible institutional assurance, like a currency board system or dollarization. Nevertheless, questions whether such corner solutions are adequate for developing countries are rising of late. "Fear of floating" is still conspicuous in many developing countries having adopted nominally a free-floating exchange rate regime. Developing countries are sensitive to exchange rate fluctuations because the cost of exchange rate volatility is greater than the benefit when compared to developed countries. Monitoring bands is a compromise solution, but it still needs further enhancement of estimation techniques for fundamental equilibrium exchange rates in order to make those estimation results more workable in practice. Other alternatives include the creation of soft peg of the G-3 currencies. Despite counterarguments, the stability of G-3 currencies could prove to be beneficial to emerging market economies.

  15. Regime Shifts and Resilience in Fisheries Management

    NARCIS (Netherlands)

    Li, Chuan Zhong; Villasante, Sebastian; Zhu, Xueqin

    2016-01-01

    We investigate the role of potential regime shifts in Argentinean hake fishery and the inter-linkage between ecological and economic resilience. We develop a theoretical model incorporated with the hazard function for resource management under alternative conditions, and derive the corrective

  16. Negotiating a regime to control global warming

    International Nuclear Information System (INIS)

    Sebenius, J.K.

    1991-01-01

    For purposes of analysis, this paper has uncritically maintained that the prospect of a serious climate problem exists and has only lightly examined the broader advantages and drawbacks of various proposed policy and institutional responses. Crucial as they are to a full treatment of the issues, these underlying substantive and policy questions enter the analysis primarily insofar as they affect the likely outcomes of pending and potential negotiations. To an advocate of a new greenhouse control regime, the fundamental negotiating task is to craft and sustain a meaningful winning coalition of countries backing such a regime. Two centrally necessary conditions for the fundamental task are: (1) that each member of the coalition see enough gain in the regime relative to the alternatives to adhere and (2) the potential and actual blocking coalitions of interests opposed to the regime be prevented from forming and from being acceptably accommodated or otherwise neutralized. The analysis of this paper is organized around key questions whose answers will influence whether and how these two necessary conditions might (or might not) be met

  17. EUROPEAN INFLUENCE ON ETHIOPIAN ANTITRUST REGIME:

    African Journals Online (AJOL)

    eliasn

    Introduction. Despite a noticeable European influence on the Ethiopian competition legal regime, some aspects of Ethiopia's 2003 Trade Practice Proclamation are still inadequate to appropriately deal with certain competition problems. The limitations of the rules need to be put right since achievement of the very goals of ...

  18. Convocation regimes for environmentalism in Brazilian business magazines

    OpenAIRE

    Jose Luiz Aidar Prado; Vinicius Prates

    2012-01-01

    The tensions between the liberal-capitalist discourse and the antagonistic discourses of environmentalism are of special interest in Brazil. This paper outlines a study of the convocation regimes employed in environmental reports published in 2010 in the two most prominent Brazilian economics and business magazines, whose communication contracts propose the modalization of executives and companies towards economic success. Its objective is to analyze how enunciators thematize environmental an...

  19. Analysis of dynamic regimes in stochastically forced Kaldor model

    International Nuclear Information System (INIS)

    Bashkirtseva, Irina; Ryazanova, Tatyana; Ryashko, Lev

    2015-01-01

    We consider the business cycle Kaldor model forced by random noise. Detailed parametric analysis of deterministic system is carried out and zones of coexisting stable equilibrium and stable limit cycle are found. Noise-induced transitions between these attractors are studied using stochastic sensitivity function technique and confidence domains method. Critical values of noise intensity corresponding to noise-induced transitions “equilibrium → cycle” and “cycle → equilibrium” are estimated. Dominants in combined stochastic regimes are discussed.

  20. The global safety regime - Setting the stage

    International Nuclear Information System (INIS)

    Meserve, R.A.

    2005-01-01

    The existing global safety regime has arisen from the exercise of sovereign authority, with an overlay of voluntary international cooperation from a network of international and regional organizations and intergovernmental agreements. This system has, in the main, served us well. For several reasons, the time is ripe to consider the desired shape of a future global safety regime and to take steps to achieve it. First, every nation's reliance on nuclear power is hostage to some extent to safety performance elsewhere in the world because of the effects on public attitudes and hence there is an interest in ensuring achievement of common standards. Second, the world is increasingly interdependent and the vendors of nuclear power plants seek to market their products throughout the globe. Efficiency would arise from the avoidance of needless differences in approach that require custom modifications from country to country. Finally, we have much to learn from each other and a common effort would strengthen us all. Such an effort might also serve to enhance public confidence. Some possible characteristics of such a regime can be identified. The regime should reflect a global consensus on the level of safety that should be achieved. There should be sufficient standardization of approach so that expertise and equipment can be used everywhere without significant modification. There should be efforts to ensure a fundamental commitment to safety and the encouragement of a safety culture. And there should be efforts to adopt more widely the best regulatory practices, recognizing that some modifications in approach may be necessary to reflect each nation's legal and social culture. At the same type, the regime should have the characteristics of flexibility, transparency, stability, practicality, and encouragement of competence. (author)