Radiation Distribution

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Hiroyuki Takahashi - One of the best experts on this subject based on the ideXlab platform.

  • a prototype of aerial Radiation monitoring system using an unmanned helicopter mounting a gagg scintillator compton camera
    Journal of Nuclear Science and Technology, 2016
    Co-Authors: Jianyong Jiang, Hiroyuki Takahashi, Kenji Shimazoe, Yasuaki Nakamura, Yoshiaki Shikaze, Yukiyasu Nishizawa, Mami Yoshida, Yukihisa Sanada, Tatsuo Torii, Masao Yoshino
    Abstract:

    Due to the accident of Fukushima Daiichi Nuclear Power Plant, some areas were contaminated by released radioisotopes (mainly 137Cs and 134Cs). Effective decontamination is demanded to encourage evacuated people to return. This paper proposes a new survey system using an unmanned helicopter equipped with a Compton camera for localizing radionuclides. As a prototype, 32 Ce:Gd3(Al,Ga)5O12 (GAGG) crystals were coupled to 16 silicon photomultipliers and 16 avalanched photodiodes as the scatterer and absorber, respectively. A new Dynamic Time-over-Threshold (dToT) method was applied to convert CR-RC shaping signals to digital signals for multi-channel spectra and coincidence acquisition. The system was designed to work in two modes: one is Compton-camera mode (CCM) which obtains the Radiation Distribution maps through Compton imaging using hovering flights, while the other one is Gamma-camera mode (GCM) which maps the Radiation Distribution via measured coincidence events using programmed flights. For point sou...

  • neutron Radiation Distribution sensor using flexible plastic scintillating fiber combined with the time of flight technique
    Nuclear Science Symposium and Medical Imaging Conference, 1995
    Co-Authors: Eiji Takada, Kazumasa Sugiyama, Hiroyuki Takahashi, Tetsuo Iguchi, M Nakazawa
    Abstract:

    As a promising neutron Radiation Distribution sensor, a long fiber system has been made using two silica fibers connected to both ends of the plastic scintillating fiber (PSF). Its basic properties were investigated to detect the position of neutron incidence with the time-of-flight (TOF) method. From the experimental results for the fission neutron source, the two linear relations were confirmed (1) between the incident position of the neutrons and the time difference and (2) between the neutron flux level and the counting rate. The spatial resolution and the counting efficiency of this system were about 60 cm (FWHM) and about 1.0/spl times/10/sup -4/ [counts/incident neutron] respectively using 1 mm diameter fiber of 100 m length. A neutron dose Distribution measured by this system was compared with the mapping result using a conventional neutron Sievert(Sv) counter. After some correction for the spatial resolution by an unfolding method, both results showed good agreement. >

  • neutron Radiation Distribution sensor using flexible plastic scintillating fiber combined with the time of flight technique
    IEEE Nuclear Science Symposium, 1994
    Co-Authors: Eiji Takada, Kazumasa Sugiyama, Hiroyuki Takahashi, Tetsuo Iguchi, M Nakazawa
    Abstract:

    A long fiber system has been made using two silica fibers connected to both ends of the plastic scintillating fiber (PSF). Its basic properties were investigated as a neutron Radiation Distribution monitor using the time-of-flight (TOF) method. From the experimental results using the fast neutron source reactor: YAYOI (University of Tokyo), the two linear relations were confirmed (1) between the incident position of and the time difference and (2) between the neutron flux level and the counting rate. The spatial resolution and the counting efficiency of this system were about 60 cm (FWHM) and about 1.0/spl times/10/sup -4/ [counts/incident neutron] respectively, with the photomultiplier gain: 6/spl times/10/sup 5/ and the discrimination level of constant fraction discriminators: 0.8 [V]. A neutron dose Distribution measured by this system was compared with the result using a conventional neutron Sievert (Sv) counter. After some correction for the spatial resolution by an unfolding method, the two results were in good agreement. >

Meng Lin - One of the best experts on this subject based on the ideXlab platform.

  • performance investigation on a linear fresnel lens solar collector using cavity receiver
    Solar Energy, 2014
    Co-Authors: Yanjun Dai, Meng Lin, K Sumathy, X K Zhao
    Abstract:

    Abstract The optical and thermal performance of a linear Fresnel lens solar collector using different types of cavity receiver is presented in this paper. The optical properties of the proposed Fresnel lens solar collector was predicted by employing Monte Carlo ray trace method and thereby Radiation Distribution as well as the impact of incidence angle on optical performance was obtained. Triangular cavity receiver was found to have highest optical efficiency of 81.2%. Thermal performance was investigated by employing both numerical and experimental method. 2D mathematical model was developed considering conductive, convective and radiative heat losses. The CFD model was then validated by comparing simulation results with experimental results. For Fresnel lens solar collector with triangular cavity receiver, the thermal efficiency was found to be around 30% at 120 °C. The analysis confirms that the Fresnel lens solar collector with triangular cavity receiver boasts best performance in terms of both optical and thermal characteristics.

Hulin Huang - One of the best experts on this subject based on the ideXlab platform.

  • design and thermal performances of semi parabolic linear fresnel reflector solar concentration collector
    Energy Conversion and Management, 2014
    Co-Authors: Hulin Huang
    Abstract:

    A Semi-Parabolic Linear Fresnel Reflector (SPLFR) solar concentrator is proposed in this paper. The SPLFR is formed by linear plate mirrors whose edges located at a parabolic line. The ray trace simulation results show the SPLFR has the same concentrating efficiency as that of the parabolic trough concentrator (PTC), but lower manufacture cost. The SPLFR concentrator has higher ground utilization ratio compared with that of Linear Fresnel Reflector (LFR) concentrator because it has no shading and blocking shortcomings. The SPLFR concentrated Radiation Distribution along the circumference of absorber pipe cross section is investigated and compared with that of LFR concentrator. The thermal performance of linear evacuated absorber for the SPLFR is simulated numerically as well. The nonuniform Radiation Distribution induces two convection eddies at each side of absorber pipe which enhances the heat transfer from the wall of absorber to the working fluid.

Perez J Pena - One of the best experts on this subject based on the ideXlab platform.

  • asymmetrical canopy architecture due to prevailing wind direction and row orientation creates an imbalance in irradiance at the fruiting zone of grapevines
    Agricultural and Forest Meteorology, 2005
    Co-Authors: Julie M Tarara, J C Ferguson, Gwenalyn Hoheisel, Perez J Pena
    Abstract:

    Much effort is invested in trellising and training grapevines to maximize Radiation interception by the canopy and to manage the Radiation environment of the fruit clusters. Slope permitting, conventional wisdom among winegrape growers prompts many to adhere to north–south row orientations to balance between the two sides of the canopy both photosynthetic efficiency and the exposure of fruiting zones to solar Radiation. In windy sites, thigmomorphogenesis in annually renewed shoots can reshape a bilaterally balanced canopy. We measured irradiance at the fruiting zone and shoot geometry in two contiguous vineyards differing only in row orientation. The prevailing west–southwest winds were roughly parallel to the rows of one vineyard and at an oblique angle to the rows of the second vineyard. Mean wind velocity in the prevailing direction was 3.3 m s 1 during the growing season. Shoots were grouped into four classes based on row orientation and shoot azimuth from the cordon. Windward shoots were significantly shorter (26–29%) than all other classes of shoots because of fewer nodes per shoot. Mean internode length per shoot (5 cm) did not vary between shoot classes and was not related to row orientation. Regardless of row orientation or initial shoot azimuth, shoot tips tended to be displaced eastward (leeward). In rows oriented roughly parallel to the prevailing wind, shoots exhibited distinct down-row streamlining and vines had a bilaterally uniform canopy about the cordon. In rows at an oblique angle to the prevailing wind the vines did not form a uniform canopy about the cordon. Both row orientations resulted in similar differences between sides of the canopy in total irradiance at the fruiting zone (+5.4 MJ m 2 d 1 on the west side of rows oriented at an oblique angle to the wind; +6.0 MJ m 2 d 1 on the south side of rows oriented parallel to the wind); however, the timing of peak intensity on the side receiving higher irradiance differed by row orientation (11.9 LST at south-facing fruit; 13.7 LST at west-facing fruit). Windinduced canopy asymmetry could result in unequal berry ripening in areas of high irradiance where peak insolation of the berries coincides with the highest temperatures of the day. Results indicate that in consistently windy locations, growers should establish row orientation based both on sun–earth geometry for maximizing Radiation interception by the canopy, and on the consequences of Radiation Distribution at the fruiting zone due to wind-induced canopy asymmetry. In established vineyards, growers could compensate for non-uniform canopy architecture to some extent with modifications to the trellis system and standard training practices.

X K Zhao - One of the best experts on this subject based on the ideXlab platform.

  • performance investigation on a linear fresnel lens solar collector using cavity receiver
    Solar Energy, 2014
    Co-Authors: Yanjun Dai, Meng Lin, K Sumathy, X K Zhao
    Abstract:

    Abstract The optical and thermal performance of a linear Fresnel lens solar collector using different types of cavity receiver is presented in this paper. The optical properties of the proposed Fresnel lens solar collector was predicted by employing Monte Carlo ray trace method and thereby Radiation Distribution as well as the impact of incidence angle on optical performance was obtained. Triangular cavity receiver was found to have highest optical efficiency of 81.2%. Thermal performance was investigated by employing both numerical and experimental method. 2D mathematical model was developed considering conductive, convective and radiative heat losses. The CFD model was then validated by comparing simulation results with experimental results. For Fresnel lens solar collector with triangular cavity receiver, the thermal efficiency was found to be around 30% at 120 °C. The analysis confirms that the Fresnel lens solar collector with triangular cavity receiver boasts best performance in terms of both optical and thermal characteristics.