Improving the performance of solar thermophotovoltaic (STPV) cells with spectral selected absorbers and small apertured radiation shields

This superconducting microscope, Figure 1, was first operated in May, 1970. The column, which started life as a Siemens Elmiskop I, was modified by removing the objective and intermediate lenses, the specimen chamber, and the complete vacuum system. The large cryostat contains the objective lens and stage. They are attached to the bottom of the 7-liter helium vessel and are surrounded by two vapor-cooled radiation shields.In the initial operational period 5-mm and 2-mm focal length objective lens pole pieces were used giving magnification up to 45000X. Without a stigmator and precision ground pole pieces, a resolution of about 50-100Å was achieved. The boil-off rate of the liquid helium was reduced to 0.2-0.3ℓ/hour after elimination of thermal oscillations in the cryostat. The calculated boil-off was 0.2ℓ/hour. No effect caused by mechanical or electrical instability was found. Both 4.2°K and 1.7-1.9°K operation were routine. Flux pump excitation and control of the lens were quite smooth, simple, and, apparently highly stable. Alignment of the objective lens proved quite awkward, however, with the long-thin epoxy glass posts used for supporting the lens.

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A 3 T superconducting magnet for long-run magnetic Compton-scattering experiments

Journal of Synchrotron Radiation ◽

10.1107/s0909049597015537 ◽

1998 ◽

Vol 5 (3) ◽

pp. 937-939 ◽

Cited By ~ 17

Author(s):

Nobuhiko Sakai ◽

Hiroshi Ohkubo ◽

Yasushi Nakamura

Keyword(s):

Magnetic Field ◽

Low Temperature ◽

Compton Scattering ◽

Superconducting Magnet ◽

Field Direction ◽

Compton Profile ◽

Magnetic Field Direction ◽

Long Run ◽

Radiation Shields ◽

The Magnetic Field

A 3 T superconducting magnet has been designed and constructed for magnetic Compton-profile (MCP) measurements with the new capabilities that the magnetic field direction can be altered quickly (within 5 s) and liquid-He refill is not required for more than one week. For the latter capability, two refrigerators have been directly attached to the cryostat to maintain the low temperature of the radiation shields and for the recondensation of liquid He. The system has been satisfactorily operated for over one week.

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AB253. Thyroid radiation shields: a potential source of intraoperative infection

Mesentery and Peritoneum ◽

10.21037/map.2020.ab253 ◽

2020 ◽

Vol 4 ◽

pp. AB253-AB253

Author(s):

Timothy McAleese ◽

James Broderick ◽

Rosemary Curran

Keyword(s):

Potential Source ◽

Radiation Shields

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Lead?Natural rubber composites as gamma radiation shields. II: High concentration

Polymer Composites ◽

10.1002/pc.10450 ◽

2002 ◽

Vol 23 (4) ◽

pp. 495-499 ◽

Cited By ~ 17

Author(s):

S. E. Gwaily ◽

M. Madani ◽

H. H. Hassan

Keyword(s):

Gamma Radiation ◽

Natural Rubber ◽

High Concentration ◽

Rubber Composites ◽

Natural Rubber Composites ◽

Radiation Shields

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Mechanically Aspirated Solar Radiation Shields: A CFD and Neural Network Design Analysis

10.1115/imece2001/htd-24287 ◽

2001 ◽

Author(s):

B. M. Fichera ◽

R. L. Mahajan ◽

T. W. Horst

Keyword(s):

Neural Network ◽

Solar Radiation ◽

Temperature Sensor ◽

Temperature Measurements ◽

Analysis And Design ◽

Computational Fluid Dynamics Analysis ◽

Radiation Shields ◽

Input Variables ◽

The Relationship

Abstract Accurate air temperature measurements made by surface meteorological stations are demanded by climate research programs for various uses. Heating of the temperature sensor due to inadequate coupling with the environment can lead to significant errors. Therefore, accurate in-situ temperature measurements require shielding the sensor from exposure to direct and reflected solar radiation, while also allowing the sensor to be brought into contact with atmospheric air at the ambient temperature. The difficulty in designing a radiation shield for such a temperature sensor lies in satisfying these two conditions simultaneously. In this paper, we perform a computational fluid dynamics analysis of mechanically aspirated radiation shields (MARS) to study the effect of geometry, wind speed, and interplay of multiple heat transfer processes. Finally, an artificial neural network model is developed to learn the relationship between the temperature error and specified input variables. The model is then used to perform a sensitivity analysis and design optimization.

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Designing and Fabricating Nano-Structured and Micro-Structured Radiation Shields for Protection against CBCT Exposure

Materials ◽

10.3390/ma13194371 ◽

2020 ◽

Vol 13 (19) ◽

pp. 4371 ◽

Cited By ~ 1

Author(s):

Kiana Nikeghbal ◽

Zahra Zamanian ◽

Shoaleh Shahidi ◽

Gianrico Spagnuolo ◽

Parisa Soltani

Keyword(s):

Computed Tomography ◽

Weight Ratio ◽

Dioctyl Phthalate ◽

Cone Beam ◽

Linear Attenuation Coefficient ◽

X Rays ◽

X Ray ◽

Nano Material ◽

Radiation Shields ◽

Shielding Properties

Researchers have always been interested in finding new and effective materials for protection against radiation. This experimental study aimed to design and fabricate new types of nano-material and micro-material based shields against the ionizing effect of cone beam computed tomography (CBCT) X-rays. To fabricate a flexible prototype, we added dioctyl phthalate (DOP) oil to emulsion polyvinyl chloride (PVC) powder. The paste was mixed and dispersed. Then, nano- and micro-powders of WO3 and Bi2O3 were added to the paste, with the weight ratio of 20% PVC, 20% DOP, and 60% nano- and micro-metals. Using an ultrasonic mixer, the polymer matrix and metals were mixed and a paste with a thick texture was developed. The resultant paste was poured into glass molds and the molds were then heated in an oven. After cooling, the resultant sheets were selected for further experiments. A CBCT unit and dosimeter were used to evaluate the characterization and X-ray shielding properties of the fabricated prototypes. The half-value layers (HVL) for nano-WO3, micro-WO3, nano-Bi2O3, and micro-Bi2O3 were 0.0390, 0.0524, 0.0351, and 0.0374 cm, respectively. In addition, the linear attenuation coefficient (µ) for these materials were 17.77, 13.20, 19.71, and 18.5 cm−1, respectively. The findings indicate that nano-structured samples are more effective in the attenuation of X-ray energy. The nano-structured WO3 prototype was nearly 34% more efficient in attenuating radiation compared to the micro-structured WO3 prototype. This difference in nano- and micro-structured Bi2O3 prototypes was 6.5%.

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