Study on Pb-Bi natural circulation phenomena

For the development of 45w%Pb-55w%Bi cooled direct contact boiling water small fast reactor (PBWFR), experimental study on Pb-Bi-water direct contact boiling two-phase flow has been performed using Pb-Bi-water direct contact boiling two-phase flow loop. For stable start-up of the boiling flow operation, Pb-Bi single-phase natural circulation must be realized in a Pb-Bi flow system of the loop before water injection into Pb-Bi. The Pb-Bi flow system consists of a four-heater-pin bundle, a chimney, an upper plenum, a level meter tank, a cooler, and an electromagnetic flow meter. A stable Pb-Bi single-phase natural circulation was realized in the range of flow rate from 1.5 l/min to 4.8 l/min by heating Pb-Bi in the heater-pin bundle with a power up to 7.7 kW. The inlet and outlet temperatures of the heater bundle were in the ranges from 243°C to 278°C, and from 251°C to 278°C, respectively. The natural circulation flow was simulated analytically using one-dimensional flow model including frictional, form and drag forces. Total hydraulic head through the loop were calculated from Pb-Bi densities at measured Pb-Bi temperatures in the loop. It was found that the calculated flow rate agreed well with the measured ones, which indicated the validity of the analytical models.     

Surface coating protective against oxidative plasma etching of polypropylene

Polypropylene (PP) sheets were coated with the ultrathin polymer layers by plasma polymerization of hexamethyldisiloxane and two other Si-containing monomers, and the protection effects from oxidative plasma etching were investigated. Etching was evaluated by the weight loss of PP sheets after the exposure to an oxidative plasma of O₂ or air. The effects of plasma polymer coating on the etching resistance were investigated with respect to the type of plasma polymer, thickness of a coating layer, oxidative plasma etching conditions, etc. Weight of the coated PP sheets was less changed and the substrates remained stable after a certain period of oxidative plasma treatments, during which time the original PP film had prominently lost weight. The importance of the crosslinked network with —Si— MPO components in plasma polymers on the etching resistance was suggested from the results. Infrared spectra were taken and analyzed with the plasma polymers after O₂-plasma treatments, and the increase in the Si—O structure was indicated by the increase in the peak intensity at 1023 cm⁻¹. Stabilization against oxidative etching was attributed to the crosslinked Si—O structure on the surface layer. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1049–1057, 1997     

Study on Pb-Bi-water direct contact boiling two-phase flow and heat transfer

For the development of 45w%Pb-55w%Bi cooled direct contact boiling water small fast reactor (PBWFR), Pb-Bi-water direct contact boiling two-phase flow loop has been fabricated and operated. The loop consists of a Pb-Bi flow loop (four heater pin bundle, a chimney, an upper plenum, a level meter tank, an air-water cooler, and an electromagnetic flow meter) and a water-steam flow loop (a pump, a preheated, an injection nozzle, the chimney, the upper plenum with mist separators and dryers, a condenser, a buffer tank, and an air-water cooler). At the rated operating condition system pressure is 7 MPa. The sub-cooled water was injected into a Pb-Bi flow in the chimney. A power of the heater pin bundle was controlled to obtain the inlet and outlet temperatures of the heater bundle. The Pb-Bi and steam flows were simulated analytically using one-dimensional models of frictional and form losses and a drag force. The Pb-Bi-steam two-phase frictional pressure loss was calculated by means of the two-phase flow multiplication factor of Lockhart-Martinelli model. It was found that Pb-Bi temperature decreased quickly in the chimney due to high heat transfer rate of Pb-Bi-water direct contact boiling. The volumetric overall heat transfer coefficient was 60–310 kW/m³K, and decreased with the superheat.     

Towards parallel I/O in finite element simulations

I/O issues in finite element analysis on parallel processors are addressed. Viable solutions for both local and shared memory multiprocessors are presented. The approach is simple but limited by currently available hardware and software systems. Implementation is carried out on a CRAY-2 system. Performance results are reported.     

Improvement of the Performance Characteristic of UWB Antenna Using a Novel Double-Layer FSSs Operating at the Ku-Band

This paper proposed a novel compact design of UWB antenna. Our design used an uni-planar EBG double-layer of FSSs to enhance performance characteristics of UWB antenna in operation frequency of 14 GHz/Ku Band. This UWB antenna occupies a compact size of 40.36?×?29.36 mm² with space/gap between the radiator patch and double-layer of FSSs is 10 mm. We used a simple rectangular truncated-corner as a radiating patch. Double-layer of FSSs consist of a lower layer of FSS that used a unit cell of rectangular loop and an upper layer of FSS applied a wire grid. Optimized size of the truncated-corner is 2?×?0.5 mm², optimal space/gap between radiator patch and double-layer of FSSs is 10 mm, and the width of a rectangular loop in the lower layer of FSS is 1.742 mm. Our proposed uni-planar EBG double-layer of FSSs based UWB antenna reaches S11 parameter of ?42.381, a ?10 dB impedance bandwidth of 1.941 GHz (12.964–14.905 GHz), and a VSWR of 1.0154 in operation frequency 14 GHz. In addition, our UWB antenna design has a high gain about 6.1 dB. Applying of uni-planar EBG double-layer of FSSs improve significantly the performance characteristic of UWB antenna.

     

Effect of the Composition Ratio Against the Electrical Conductivity Properties and the Wear Rate of the Composite

This article reveals the wear rate and electrical bottle with a phenolic resin matrix. The study was initiated and waste glass bottles to reach the mesh size of 〉 300. conductivity of composites made of carbon powder and waste of glass with a carbonization of coconut shell, pulverized and filtered the carbon Both materials were mixed with a composition ratio of carbon： glass, 70%：30%; 80%：20%; and 90%： 10% weight. The mixture was mixed with phenolic resin adhesive and compacted with a load of 5 US ton. Results showed, the higher the carbon content, resulting in the higher the electrical conductivity, but also showed the lighter composite. Increased content of carbon powder made lighter composite, it also made the softer composite, so that the higher wear rate. Lowest wear rate was showed by a mixture of carbon-glass composite with a composition ratio of 70：30, which was 6.86738E-06 mm3/Nm. Carbon powder was softer than glass powder, the highest rate was indicated by the carbon-glass composite with 90：10 composition, which was 8.67425E-06 mm3/Nm. A high content of carbon powder encouraged an increase electrical conductivity of the composite. Mixture of carbon-glass composite with the composition ratio of 90：10 produced electrical conductivity of 0.192 S/m.     

Improvement of Processability of PCL and PBS Blend by Irradiation and its Biodegradability

Poly(ε‐caprolactone) (PCL) was blended with poly(butylene succinate) (PBS), (PCL/PBS = 30/70) to improve the heat stability of PCL. The processability of the blended samples (PHB02) was improved due to enhancing of melt strength by γ‐rays irradiation in the dose range between 10 and 50 kGy. High speed production of a thin film and production of foam have been achieved by this process. The soil degradation test showed that PHB02 film buried in the soil was almost degraded (97%) after two months and completely degraded after two and a half months. On the contrary, the sample on the surface degraded to only 3.5% after four months. From these findings it was confirmed that microorganisms contribute to degradation in the soil. In the case of PHB02 foam samples, 65% degradation was achieved after four months. The PHB02 sample used as garbage bags was well degraded (almost 50%) after a two months burial test. The enzymatic degradation test showed that after treatment for 24 h, the weight loss of PHB02 irradiated with 30 kGy and unirradiated samples were 80% and 90%, respectively. Enzymatic degradation for PHB02 films led to the suggestion that the biodegradation process proceeds from the surface to the inside of the sample by erosion.