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To predict round window membrane (RWM) visibility and electrode insertion sites using high-resolution computed tomography (HRCT) in pediatric cochlear implant surgery. Sixty-two ears of 36 infants less than 1 year old were included in our study. Intraoperative RWM visibility was classified into three types corresponding to three different surgical approaches. Radiologic parameters were measured on preoperative axial temporal HRCT images and correlated with RWM visibility and surgical approaches. A significant correlation was found between the degree of RWM visibility and the following two parameters: 1) a line (l w) was drawn from the posterior margin of the RWM to the intersection point of the posterior wall of the external auditory canal (EAC) and mastoid cortex. Another line (l f) was drawn between the posterior margin of the RWM and the lateral margin of the FN. The angle between l w and l f was measured as angle A, P < 0.01, R2 = −0.809; 2) a line (l m) was drawn from the anterior to posterior margin of the RWM, and the angle between l m and l f was measured as angle B, P < 0.01, R2 = −0.850. A nonsignificant correlation was found between the degree of RWM visibility and the facial recess width, p > 0.05, R2 = −0.00015. RWM visibility showed a high correlation with the two angular measurements (angle A and angle B) and was associated with electrode insertion sites. In children less than one year old, surgeons can depend on those two parameters in predicting the RWM visibility. [ABSTRACT FROM AUTHOR]

Highlights • Experimental and numerical study of helium flow characteristics was conducted. • The particle diameters of packed beds are less than 2 mm. • Ergun correlation modified with the compressibility was deduced. • The numerical results are in good agreement with the experimental results. Abstract The high temperature gas cooled reactor (HTGR) with a packed pebble bed core has been one of the fourth generation reactors. The helium cooled pebble bed (HCPB) blanket packed spherical pebbles of lithium orthosilicate (Li 4 SiO 4) has been recommended to Chinese Fusion Engineering Test Reactors (CFETR). Helium flow characteristics in spherical pebble bed are the key issues to design the pumping power. In this work, helium flow characteristics in a rectangular pebble bed channel filled with stainless steel particles whose diameters are 0.5 mm, 0.8 mm, 1.0 mm, 1.5 mm, and 2.0 mm, respectively, were investigated experimentally and numerically. The experimental results show that the compressibility cannot be neglected and it has an important influence on flow characteristics in the conditions with the enough large ratio of pressure drop to system pressure. Ergun correlation was compared with experimental values, and Ergun correlation modified with compressibility was deduced. The results show that Ergun correlation modified with compressibility can improve the ability to predict experimental values. The numerical results show that the particle friction factors modified with compressibility (f p *) in a rectangular pebble bed channel randomly filled with spherical particles can be predicted by using the models with SC-1, BCC-1, and FCC-1 arrangements. This work would provide some supports for the design of the helium supply system of the packed bed reactors. [ABSTRACT FROM AUTHOR]

Abstract A conceptual structure design of the supercritical water cooled ceramic blanket has been proposed for phase-II of Chinese Fusion Engineering Test Reactor (CFETR). In this work, the coupled neutronic/thermal-hydraulic/mechanical analyses were performed specifically for the optimized blanket concept as well as the design process. Firstly, the 3D-1D-3D coupling approach was applied in the neutronic and thermal-hydraulic calculations after the materials were carefully selected. The different results of the 3D model and 1D model have been compared and analyzed. Secondly, the detailed design of the typical outboard equatorial blanket was carried out and introduced based on the coupling analysis. Then, the neutronic, thermal-hydraulic and mechanical characteristics of the optimized blanket were studied and verified. The 3D neutronic calculations of the blanket indicated the tritium breeding ratio (TBR) is 1.21, which can meet the requirement for tritium self-sufficiency. The thermal-hydraulic calculations proved that all the involved materials can be effectively cooled to their allowable temperatures with the coolant temperature reaching 500 °C. According to thermo-mechanics calculation results, the blanket structure (first wall, caps, coolant pips, etc.) can certainly sustain the structure stress as well as the thermal stress in steady state. The analyses show good performances of the blanket and prove the feasibility of the conceptual design preliminarily. [ABSTRACT FROM AUTHOR]

• A 2D numerical simulation model for tritium release from Al 2 O 3 -coated FeCrAl fuel rods was developed. • Sievert's law and the Soret effect equations were coded and studied in the model. • The low release rate indicates that the Al 2 O 3 coating prevents tritium release effectively. • Tritium concentration at the gap is much higher than the inner cladding for Al 2 O 3 -coated fuel rods. • Locally uncoated defects lead tritium flux to bypass Al 2 O 3 coating and be released outside the fuel rod. FeCrAl is one of the ATF cladding solutions due to its excellent oxidation resistance. In this work, a 2D numerical simulation method was developed to study tritium release from the nuclear fuel pellets to the fuel-cladding gap, tritium adsorption on the inner surface of the cladding, and permeation through Al 2 O 3 -coated FeCrAl cladding into the coolant. For Al 2 O 3 -coated fuel rods, based on Sievert's law, tritium concentration at the pellet-cladding gap is much higher than that at the inner cladding surface for most of the time under normal conditions, which slows down the tritium release rate from the fuel rods. With Al 2 O 3 coating, tritium release from the fuel rods remains rising throughout the lifetime. The release rate is calculated to be low at the end of the lifetime, indicating that the Al 2 O 3 coating prevents tritium release. As the coating thickness decreases, the flux of tritium release is found to be increased. Locally uncoated drawbacks lead tritium in the gap to be preferentially adsorbed by the inner surface of FeCrAl, then diffused in FeCrAl, and finally released outside the fuel rod. Still, more actual irradiation operations and test data are needed. [ABSTRACT FROM AUTHOR]

The surface microstructure of biomimetic Procambarus clarkia claw was prepared on the surface of GCr15 steel, then PTFE solid lubricants dispersed with three different hardness nanoparticles (C, ZnO, Al 2 O 3) were filled in. The results of the tribological experiment show the textured surface lubricated by PTFE with Al 2 O 3 nanoparticles reflected the best performances. Because PTFE stored by the bionic texture could be supplied to the friction surface to form a solid lubrication film. Due to the addition of Al 2 O 3 nanoparticles, the hardness and wear resistance of the film are improved, thus avoiding a large loss of PTFE. And the process of "rolling-embedding PTFE surface-exposing-rolling" occurs. As a final, the surface tribological properties of GCr15 steel can be significantly improved. • The PTFE could be supplied to the friction surface to form a solid lubrication film. • The Al 2 O 3 nano-particles enhance hardness and wear resistance of lubricant film. • The textured surface lubricated by PTFE with Al 2 O 3 reflected the best performance. [ABSTRACT FROM AUTHOR]

Since fuel elements will be exposed to high temperature and strong irradiation for a long time, the safety of space reactor is challenged not only when an accident happens but also during the normal operation. With the full consideration of plastic deformation and high-temperature creep, a new mechanical model for fuel elements in space reactor was developed. By calculation result comparison of the new model and ABAQUS, the correctness and reliability of the new model was validated. This model was implemented in FROBA code to simulate the thermal-mechanical performance of a space reactor fuel during the long-term normal operation. The result indicated that the fuel element was safe enough during the most time of normal operation, but it experienced some periods with over high fuel temperature or low thermoelectric conversion efficiency. In addition, it was found that high temperature creep of the emitter can release the pellet-emitter contact pressure and protect the emitter from mechanical failure when power remained unchanged or changed slightly. However, the stress of emitter might exceed its strength limit during the power ramp. [ABSTRACT FROM AUTHOR]

Amorphous Fe78Si13B9 alloy ribbons were bombarded by ion beams with different incident angles (θ). The evolution of the microstructure and magnetic properties of ribbons caused by ion beam bombardment was investigated by x-ray diffraction, transmission electron microscope and vibrating sample magnetometer analysis. Low-incident-angle bombardment led to atomic migration in the short range, and high-incident-angle bombardment resulted in the crystallization of amorphous alloys. Ion bombardment induces magnetic anisotropy and affects magnetic properties. The effective magnetic anisotropy was determined by applying the law of approach to saturation, and it increased with the increase of the ion bombardment angle. The introduction of effective magnetic anisotropy will reduce the permeability and increase the relaxation frequency. Excellent high-frequency magnetic properties can be obtained by selecting suitable ion bombardment parameters. [ABSTRACT FROM AUTHOR]

The crystallization behavior of Fe 78 Si 13 B 9 amorphous alloys induced by Ar ion bombardment was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. The crystallization process of amorphous alloys can be controlled by adjustment of ion incident angles (θ), beam density and substrate temperature. The compressive stress caused by ion bombardment will result in the decrease of critical nucleation energy and induce the crystallization of amorphous alloy even at very low temperature, and the thermal effect converted from energetic ions will improve the crystallization of amorphous alloys. The crystallization process of amorphous alloy induced by ion bombardment was a stress induced phase transformation process assisted by thermal effect. [ABSTRACT FROM AUTHOR]