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Combustion Structure of a Cylindrical Rotating Detonation Engine with Liquid Ethanol and Nitrous Oxide
No full textLiquid propellants are commonly used in rocket engines due to their high energy density. In this study, we focused on the use of liquid ethanol and liquid nitrous oxide as propellants in a cylindrical rotating detonation engine (RDE) for practical applications, and examined the effects of various conditions on the bipropellant RDE performance. We varied the vapor quality of nitrous oxide in a mixture of liquid and gaseous nitrous oxide due to the flash boiling. In addition, we varied the liquid ethanol temperature, the injector stiffness, and momentum angle of the propellant. We then analyzed the effects of these changes on the propagation mode of the RDE under atmospheric pressure conditions. The results showed that a rotating detonation wave was observed under the combination of high vapor quality of nitrous oxide, high injector stiffness, high liquid ethanol temperature, and high momentum angle. The propagation velocity was obtained as 73∼83 % of the Chapman-Jouguet velocity. Long-duration combustion tests were also conducted, and the internal combustion structure was confirmed from the erosion of the carbon-carbon (C/C) composite material. The detonation wave was considered to propagate near the bottom of the RDE with liquid propellants from the erosion heights of the C/C composite. The erosion height was confirmed to be consistent with the fill height calculated using the sound speed of the nitrous oxide. In addition, characteristic exhaust velocity efficiencies of more than 85 % were achieved in all combustion tests
台湾における原子力安全規制機関の独立性と透明性
No full textTaiwan has not yet been singed the “Convention on Nuclear Safety; CNS” that was adopted by the International Atomic Energy Agency （IAEA） in 1994. However, if these international activities help promote nuclear safety, Taiwan must participate in it and fulfill its related obligations. Therefore, despite Taiwan being a non-member state to the CNS, it is required by the Convention to act as a member state to meet all the requirements addressed in the CNS. Ensuring the public trust of nuclear safety regulations in the most important policy issue for the location, operation, waste disposal and off-commissioning of nuclear power plants, etc. As part of an international comparison of nuclear safety regulatory bodies in the East Asian region, this note organizes and evaluates the independence and transparency of Taiwan’s regulatory bodies
Improving thermoelectric properties of Bi2Te3 by straining under high pressure: Experiment and DFT calculation
No full textBi_2Te_3 intermetallic compounds show high thermoelectric performance near room temperature and are widely used for cooling and power generation applications. It is still necessary to improve its dimensionless figure of merit zT for large-scale industrial use. In this study, high-pressure torsion processing is applied to Bi_2Te_3 powder samples to investigate the crystal structure and enhance their thermoelectric properties. The processed Bi_2Te_3 samples show reduced cell volume, higher electrical conductivity, enhanced Seebeck coefficient and higher zT value compared with the original powder sample, even if the grain refinement is not remarkable. First-principles calculations are also used to investigate the electronic structure and thermoelectric properties to clarify the influence of high-pressure torsion processing
自然破裂を来たしたChromophobe腎細胞癌の1例
No full textSpontaneous rupture of renal cell carcinoma (RCC) occurs in 0.3-0.6% of all RCC cases. A 57-yearold woman presented to the emergency department with a chief complaint of hematuria and lower back pein. Ruptures of a kidney tumor and a kidney capsular hematoma were detected using computed tomography. The patient underwent radical right nephrectomy 22 days post admission, and the pathological diagnosis was chromophobe RCC (ChRCC). To our knowledge, this is the third reported case of ChRCC. The previous two cases did not exhibit postoperative recurrence, and yielded good prognoses. However, in our case, liver metastasis occurred 1 month postoperatively, and the prognosis was poor
Seedless and electroless plating of silver on silica particles by using microreactor
No full textSynthesis of silver nanoshells is still a challenge especially in the absence of surface modification of core particles and/or metal seed decoration on core surfaces. In this study, we applied a microrector to seedless and electroless plating of silver on bare silica particles, and investigated the effects of reaction temperatures and silver ion concentrations on the morphology and surface coverage of silver on the core particle surface. Our experiments demonstrated that the use of the microreactor enabled the one-step direct deposition of silver with a morphology close to complete shells and that silver ion concentrations from 0.2 to 0.5 mM at a moderate temperature of 50 °C produced high coverage and yield. Besides, the mixing sequence of NH3 and HCHO in the synthesis procedure was found to be a key factor to achieve the high silver coverage. In addition, we demonstrated that the addition of polyvinylpyrrolidone (PVP) after the silver shell growth reaction increases the stability without decreasing the reaction rate