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Abstract High collecting temperature in parabolic trough collectors (PTCs) induces considerable radiative heat loss of solar receivers, which causes significant negative effects on heat-collecting efficiency. Structural optimized solar receivers with inner radiation shield achieved superior thermal performance for reducing heat loss. Based on widely commercial EuroTrough and PTR70 solar receivers, the optimized solar receivers are numerically applied to a small thermal-collection field with 72 m loop using molten salt as heat transfer fluid to validate their enhanced overall performance. Mathematical models relying on spectrum parameter calculation and working fluid volume unit method are established to simulate the energetic and exergetic performances of the solar receivers. The influence of solar irradiance on parabolic trough collector system is studied, and all-day system efficiencies in different areas in China are investigated to validate the performance of the proposed solar receivers in real condition. Results show that the PTCs with novel solar receivers exhibit outstanding energetic and exergetic performances compared with conventional receivers. The heat loss reduction percentage of the novel receivers reaches approximately 24.0% when the absorber temperature is 600 °C. The heat-collecting efficiency and exergetic efficiency are effectively raised by 7.1% and 4.7%, respectively, at an inlet temperature of 580 °C. Highlights • Energetic and exergetic performance of PTC with novel solar receivers is studied. • Mathematical models with spectral radiant distribution are built and validated. • All-day PTC system efficiency in different areas in China is calculated. • The radiation heat loss of the novel receiver is reduced by around 24.0%. • Thermal and exergetic efficiencies of novel receiver are raised by 7.1 and 4.7%. [ABSTRACT FROM AUTHOR]

• The neutronic parameters for the ARGUS reactor are calculated. • The 6 group effective delayed neutrons fractions are obtained. • The hot full power k eff and fuel burnup are calculated. • The control rods worth, the shot down margin and the safety reactivity factor are calculated. • The temperature coefficient of reactivity and void coefficient of reactivity are calculated. • Two different types of radiation shield for gamma and neutron radiations are designed. In this research, an aqueous homogeneous reactor is simulated and its neutronic parameters are investigated. Due to the negative reactivity caused by temperature change and void formation, the cold excess reactivity is considered equal to 4 β eff. Also, calculations of radiation shielding and neutronic characterization of the reactor are performed. For different heights of uranyl sulfate fuel, the effective multiplication factor (k eff) of the reactor is calculated under cold zero power and hot full power conditions to assess the required excess reactivity. The amount of fuel burnup and changes in the k eff are investigated for 500 days, finally 200 operating days are chosen as the working duration of the reactor. The control rods worth (CRW) for different diameters of boron carbid and reactor safety parameters including shot down margin (SDM) and safety reactivity factor (SRF), temperature and void coefficients of reactivity are analyzed. In order to design a suitable radiation shield for this reactor, two different shields are considered. The first shield is a combination of polyethylene thicknesses and barite concrete, and the second shield is made only of barite concrete. The total thickness of the first and second shield was 230 and 180 cm, respectively. Due to the problems of using polyethylene (e.g. problems related to machining, shield dimensions and low melting temperature), the second shield is chosen as the suitable radiation shield for this reactor. Using this radiation shield, the total dose rates of neutron and gamma rays satisfy the ICRP dose limits. [ABSTRACT FROM AUTHOR]

Innovative multifunctional materials that combine structural functionality with other spacecraft subsystem functions have been identified as a key enabling technology for future deep space missions. In this work, we report the structure and performance of multifunctional polymer matrix composites developed for aerospace applications that require both structural functionality and space radiation shielding. Composites comprised of ultra-high molecular weight polyethylene (UHMWPE) fiber reinforcement and a hydrogen-rich polybenzoxazine matrix are prepared using a low-pressure vacuum bagging process. The polybenzoxazine matrix is derived from a novel benzoxazine resin that possesses a unique combination of attributes: high hydrogen concentration for shielding against galactic cosmic rays (GCR), low polymerization temperature to prevent damage to UHMWPE fibers during composite fabrication, long shelf-life, and low viscosity to improve flow during molding. Dynamic mechanical analysis (DMA) is used to study rheological and thermomechanical properties. Composite mechanical properties, obtained using several standardized tests, are reported. Improvement in composite stiffness, through the addition of carbon fiber skin layers, is investigated. Radiation shielding performance is evaluated using computer-based simulations. The composites demonstrate clear advantages over benchmark materials in terms of combined structural and radiation shielding performance.

Temperature measurements of InterMET Inc. aluminum-coated iMET-XQ sensors were tested in an outdoor setting under a variety of solar radiation and wind speed conditions. Twelve unshielded sensors were mounted side-by-side on the tower of a South Alabama Mesonet weather station next to a reference sensor on the tower. The iMET-XQ temperatures were most precise and accurate in solar radiation values that were close to zero, regardless of wind speed. Under overcast conditions, wind speeds of 2 m s−1 were sufficient to obtain precise and accurate temperature measurements. During the day-time, aspiration of wind speeds higher than or equal to 3 m s−1 is sufficient. An iMET-XQ was placed in a radiation shield next to the tower reference sensor to test the need for a radiation shield. A second iMET-XQ was placed unshielded on the tower. The iMET-XQ sensors with aluminum coating do not need to be shielded, but they do need to be aspirated. It is recommended that, when taking temperature measurements using unmanned aerial vehicles (UAV) with iMET-XQ sensors, the UAV either fly at 3 m s−1, be embedded in winds of those speeds, or to use the propeller wash of the UAV to aspirate the sensors.

Abstract Glasses in the series, 49B 2 O 3 -25SiO 2 -(26-x)Bi 2 O 3 -xBaO (with x between 2 and 8 wt%) are considered for radiation shielding applications based on the gamma-ray half-value layer (HVL) and mass neutron removal cross-section. Theoretical data for the calculation of the HVL is obtained from the NIST XCOM software. The calculated HVL shows good correspondence to the experimentally determined values. The mass neutron removal cross-section and the half-value layer of the glass system are optimized using the genetic algorithm. The genetic algorithm is used alongside regression analysis to determine the relative concentration of each oxide needed to obtain the best radiation shielding parameter values. The use of numerical methods is employed to ascertain simple functions that can be used instead of traditional analytical functions in modeling the behavior of glasses. The auto-Zeff software is used to generate a plot of the effective atomic number over a spectrum of photon energies, while spectroscopic techniques are used to examine the structure and optical properties to determine what advantages the glasses have over concrete or water. This approach had fast convergence due to increased numerical stability. The optimal solution is equal to barite concrete in gamma-ray shielding and limonite concrete in neutron shielding. Highlights • The genetic algorithm is successfully applied to the optimization of oxide glass. • B 2 O 3 -SiO 2 -Bi 2 O 3 -BaO glasses have HLV below 2.8 cm at 662 keV. • B 2 O 3 -SiO 2 -Bi 2 O 3 -BaO is comparable to heavy concrete in shielding parameters. • The correlation between wt. fraction and shielding parameter simplifies optimization. • Higher oxygen content in HMO glasses improves neutron shielding. [ABSTRACT FROM AUTHOR]

Highlights • Conduction/radiation combined heat transfer is analyzed for applications in VIP. • Influences of emissivities and contact resistance on heat transfer are studied. • Conduction/radiation interaction can increases heat transfer by more than twice. • Use of reflective shields with contact resistance are recommended in VIPs. Abstract Combined heat transfer of conduction and radiation is investigated with thermal contact resistance boundary condition to scrutinize the effect on heat transfer and to evaluate the thermal performance of vacuum insulation panels (VIPs). Numerical analysis shows that introduction of contact resistance flattens temperature profile and reduces both the conductive and the radiative heat transfer. In VIPs, if interstitial material is purely absorbing/emitting and well contacting the radiation shield, center-of-panel thermal conductivity can be more than twice larger than that estimated by separate analysis of conduction and radiation, especially when the optical thickness of the layer is moderate and the wall emissivity is low. On the other hand, this error decreases with increased scattering albedo and reduced conduction/radiation interaction. In any case, use of low-emissivity shields greatly improves the insulation performance. Further, contact resistance between the interstitial material and the shields reduces the heat transfer substantially. Thus, insulation performance of VIP with artificial core structures can be greatly improved by employing rough or embossed, and highly reflecting shields. [ABSTRACT FROM AUTHOR]

A novel solar evacuated receiver as the key part of parabolic trough collector (PTC) was designed and constructed by authors. The novel evacuated receiver (NER) with an inner radiation shield can significantly decrease heat loss at higher operating temperatures when compared with the traditional evacuated receiver (TER). A thermodynamic model relying on the spectrum parameter model of radiation heat transfer was developed to predict the performances of evacuated receivers. Also, experiments using the novel evacuated receiver and traditional evacuated receiver were conducted in the laboratory under different parametric conditions to validate results obtained for the simulation. A comparison between simulation results and experimental data demonstrated that the model was able to yield satisfactory consistencies and predictions to a reasonable accuracy (with the root mean square deviations less than 6%). Results indicated that the novel evacuated receiver has a role in decreasing the total heat loss of receiver compared with the traditional receiver when the working temperature is higher than 296 °C, the heat loss reduction percentage of the novel evacuated receiver reaches 19.1% when the operating temperature is 480 °C, and the value of this percentage would be greater at higher working temperatures. [ABSTRACT FROM AUTHOR]

Percutaneous angioplasty (PTA) for dysfunctional hemodialysis is usually performed by radiologists, but not cardiologists, in Taiwan, so that the radiation dose in patients and physicians are usually unknown and related studies are rare. In this study, we are pioneering an investigation into the radiation dose in percutaneous angioplasty for arteriovenous shunt assembling and the effect of RADPAD device, a lead-free surgical drape containing Bi and Ba, on the decrease of a radiation dose in the non-targeted organs of the patient and also the operator. The radiation dose in a typical digital subtraction angiography (DSA) by the PTA protocol under a fixed field of view (FOV), was measured with optically simulated luminescent dosimeters arranged in a PIXY RS-102 anthropomorphic phantom. The results indicate that there is a significant dose reduction at the hands (0.022±0.002 mGy before treatment vs. 0.014±0.001 mGy after treatment; P=0.021), but not at the lens (0.027±0.003 mGy before treatment vs. 0.018±0.001 mGy after treatment; P=0.058), and the gonads (0.026±0.003 mGy before treatment vs. 0.020±0.001 mGy after treatment; P=0.058), of the cardiologist/operator after treatment with the RADPAD drape. At the patient's abdomen, the dose significantly decreased from 1.597±0.104 mGy to 0.031±0.002 mGy (P<0.001) after treated with the RADPAD shield. For the chest, lens and thyroid in the patient, the doses were respectively 0.154±0.100 mGy (compared to 0.049±0.001 mGy after treated with the RADPAD drape; P=0.0002), 0.066±0.001 mGy (compared to 0.021±0.001 mGy after the RADPAD treatment; P=0.009), and 0.208±0.002 mGy (compared to 0.042±0.003 mGy after shielded with the RADPAD drape; P<0.0001), which represents an apparent reduction in dose. However, no significant difference was found in the dose-area product between before (179.9±0.1mGy.cm 2 ) and after (177.4±0.1mGy.cm 2 ) the treatment (P=0.38). In conclusion, the RADPAD drape significantly reduced radiation exposure to the patient during the PTA for the arteriovenous shunt assembling, which is suggested should be applied to the current cardiac catheterization. [ABSTRACT FROM AUTHOR]

The cryo-condensation pump used in EAST-NBI is composed of cryo-condensation panels cooled by liquid helium and radiation shields cooled by liquid nitrogen. The transmission probability of radiation shields has great influence on the performance of the cryo-condensation pump. The Monte-Carlo method is applied to simulate the trajectories of the deuterium molecules and to study the effects of the structure of the radiation shields on the transmission probability. By adding imaginary walls, the distribution of positions and flying directions of the molecules is presented. The results indicate that the uniformity of the molecules is the direct factor to influence the transmission probability. [ABSTRACT FROM AUTHOR]

In this study, has been investigated the rate of heat transfer between engine and vehicle body room in steady state using analytical methods and the concept of net radiation heat transfer and energybalance equation at the boundaries. Also, calculated the net radiation heat transfer,percentage reduction in heat transfer, temperature and emissivity while there are one, two and three radiation shields with temperature- dependent emissivity.The findings reveal that,one radiation shield with lower emissivity can reduce the net heat transfer even better than two radiation shields with higher emissivity.Also, Is obtained an optimized for combination of two and three radiation shields with different materials.