二垩英与资源回收-Ⅰ考虑到二垩英生成的资源与能量回收基础研究

目前在日本,存在大量工业垃圾,包括各种塑料制品,ASR(汽车破碎垃圾),含有毒PCB(多氯联苯)的110变压器和PVC(聚氯乙稀)制品等.而来自城市垃圾焚烧炉的废气含有大量能量.因此,在充分考虑环境、避免二垩英生成的同时,安全回收来自工业垃圾、城市和/或工业垃圾焚烧炉的资源和能量是个非常重要的课题,这也将对抑制CO2排放作出贡献.正确地阐明焚烧过程中二垩英的生成机理及详细研究含少量二垩英的焚烧废气在冷却过程中大量形成二垩英的临界温度是项很重要的工作.解决这个问题可有效实现资源和能量的回收.本报告介绍日本在二垩英排放方面目前采取的对策和存在的问题以及大阪大学为阻止二垩英生成所做的基础研究工作.     

Robust and accurate prediction of thermal error of machining centers under operations with cutting fluid supply

A novel temperature measuring system named LATSIS was proposed to realize a robust and accurate prediction of the thermal deformation of machining centers, even under external disturbances such as cutting fluid supply. LATSIS enables a drastic increase in the number of sensors employed for measuring the temperature of the machine tool. Thus, the entire temperature distribution can be obtained by interpolating the measured temperature 3-dimensionally without calculating the heat conduction. A set of experiments was conducted in which the LATSIS was employed to predict the TCP error. A total of 284 sensors were placed on the machining center, and the TCP error was predicted based on the measured temperature for the situation with/without the cutting fluid supply. The results of the prediction showed good agreement with the measured TCP error even during the initial transient temperature change as well as in the cooling phase after the machine halt. The TCP error with the cutting fluid supply is accurately predicted. LATSIS was proven to be a robust and accurate method for predicting the thermal deformation of machine tools, and is a promising technology for future manufacturing systems.     

Effect of collagen fibril formation on bioresorbability of hydroxyapatite/collagen composites

Porous hydroxyapatite/collagen (HAp/Col) composite is a promising biomaterial and a scaffold for bone tissue engineering. The effect of fibril formation of Col in the porous composite on bioresorbability and mechanical strength was investigated. The fibril formation, in mixing a self-organized HAp/Col nanocomposite and sodium phosphate buffer at a neutral condition, occurred during incubation at 37 °C, resulting in gelation of the mixture. The porous composites with and without the incubation were obtained by freeze-drying technique, in which macroscopic open pores were formed. The compressive strength of the porous composite with the incubation (34.1 ± 1.6 kPa) was significantly higher than that without the incubation (28.0 ± 3.3 kPa) due to the fibril formation of Col. The implantations of the porous composites treated with a dehydrothermal treatment in bone holes revealed that bioresorption was clearly depended on the fibril formation. The bioresorbability in vivo was almost matched to the in vitro test using enzymatic reaction of collagenase.     

Fundamental Study on Continuous Casting Process With Swirling Flow by Electromagnetic Force

Swirling flow in a submerged entry nozzle is effective on improving quality of casting block and casting speed in continuous casting of steel.A new method for swirling flow generation in the nozzle has been proposed by the authors,that is a rotating electromagnetic field is set up around a submerged entry nozzle(SEN)to induce swirling flow in it by Lorentz force.In this study,the magnetic field in molten steel in the submerged entry nozzle,the flow and temperature field in the SEN and mold in round,square billet and slab continuous casting process of steel are numerically studied.The model experiment of electromagnetic swirling continuous casting is also conducted with low melting point alloy.The commercial test for slab is undergoing.Results by numerical simulation and experiment show that the swirling flow by the optimum designed electromagnetic swirling generator can not only improve the distribution of flow and temperature in mold but also achieve the same effects generated by the swirling blade process.And,more effects on continuous casting process can be expected after this electromagnetic swirling process is optimized.     

钢圆坯连铸过程中渐开式电磁旋流水口数值模拟

提出了一种新的浸入式水口内产生旋流的方法.即在水口外施加可移动的旋转电磁场,非接触地形成钢液旋流.为进一步发挥旋流作用,采用渐开式水口,对圆坯连铸中浸入式水口及结晶器内钢液流场、温度场进行了三维数值模拟,并重点研究了水口渐开角度结合不同旋流强度对结晶器内流场及温度场的影响.研究结果表明,浸入式水口内磁场和旋流速度随着线圈电流强度的增加而增加.当电流强度为500 A,频率为50 Hz时.可产生最大为3 m/s左右的旋流速度.当水口采用同一渐开角度,随着旋流强度的增大,水口出流的冲击深度减小,上返流增强,弯月面温度提高.但当旋流强度增大到一定程度后,结晶器内弯月面附近温度变化不大.采用同一旋流强度,随着水口渐开角度的增加,结晶器内水口出口上方的上返流先增强后减弱,在渐开角度为60°时,上返流最强.同样,弯月面附近温度也是先提高后有所降低,在渐开角度为60°时,弯月面温度最高.水口渐开角度为60°,线圈电流350 A,频率为50 Hz时,在水口入口处施加0.5 m/s水平速度的人工偏流后,电磁旋流能对该偏流进行有效的抑制.     

Suppression of Effect of Uneven Velocity in Submerged Entry Nozzle in Round Billet Continuous Casting Process Using Electromagnetic Swirling Flow

Sliding gate control system is widely employed in continuous casting process of steel to control flow rate of molten steel.As molten steel passes through a sliding gate,uneven flow develops.This will cause asymmetrical distribution of flow and temperature field in mold consequently,formation of vortex near the nozzle and entrapment of CC powder into the molten steel.etc,which have negative effect on process productivity and product quality.To suppress the uneven flow,electromagnetic swirling flow has been proposed to impose on the flow in submerged entry nozzle below the sliding gate.In this study the uneven flow developed by incompletely open sliding gate and the suppression of this uneven flow using electromagnetic swirling flow are numerically studied in round billet continuous casting of steel process.The improvement of the flow and temperature filed in the submerged entry nozzle and mold are investigated.It is found that:The uneven velocity in nozzle can be suppressed by electromagnetic swirling flow,and the flow and temperature field in mold be improved obviously;With the increase of electromagnetic swirling intensity,the effect of uneven flow can be almost completely suppressed.     

二垩英与资源回收-Ⅲ燃烧过程二垩英生成热力学计算

进行相关热力学计算以研究高温燃烧过程二垩英生成的条件.计算得到:①在体系存在过剩氧即完全燃烧时不会产生二垩英;②当有固体碳沉积时也不会生成二垩英,因固体碳在热力学上比含二垩英的含碳物更稳定.另一方面,实际上即使在1 073 K完全燃烧条件下(即体系显著过剩氧)也有二垩英生成,原因是在实际燃烧炉中含碳微粒不可能完全烧尽.从热力学角度假设不发生碳沉积,计算得出二垩英在1 073 K高温和高CO/CO2比范围内会生成.实际考虑的条件放在燃烧炉内含碳微粒的周围.在有含碳微粒存在条件下,即使反应2CO→C+CO2(碳沉积)发生,C+CO2→2CO反应(CO生成;含碳微粒被CO2氧化)也会同时发生,导致在含碳微粒周围保持一个高的CO/CO2比,由此产生二垩英.假设在含碳微粒周围存在高CO/CO2比的异质位置,则认为二垩英会形成.     

Benign asbestos pleural effusion associated with pulmonary aspergilloma

A rare case of benign asbestos pleural effusion associated with aspergilloma is reported. A chest radiograph of a 75-year-old Japanese man who was admitted with right chest pain showed a right pleural effusion and nodular shadows in the right apex and left middle lung field. Thoracocentesis revealed an exudate with atypical mesothelial cells. An open lung biopsy showed aspergilloma in the right S2 area and no evidence of malignancy. Many reactive mesothelial cells were found in the pleura. A quantitative asbestos digestion study of the lung tissue biopsy showed high-grade asbestos exposure.     

Numerical analysis of overhead transmission line galloping considering wind turbulence

This study aims at clarifying the factors that cause transmission line galloping and the conditions influencing it, and at determining response evaluation indices of gallopings in turbulent flows. This is done using a three‐dimensional analytical method considering a large deformation. The analysis is based on four‐bundle transmission lines. Obtained results are as follows:

• 1 The occurrence of galloping in the smooth flow is limited by the combination of the following parameters: the initial angle of wind attack, the initial icing angle, and the wind speed. The galloping predominates mainly with one or two of the lowest in‐plane, out‐of‐plane, and torsional modes for the free vibration under the conditions that the transmission line is subject to dead load as well as static wind force. However, the galloping always occurs with torsional vibration.
• 2 The shape of the Lissajous figure for displacement depends on the initial angle of wind attack and the initial icing angle, as well as wind speed. The main shapes are vertically elliptic, horizontally elliptic, and a configuration having the shape of a horizontally rotated figure of eight.
• 3 The predominant frequency components of gallopings in turbulent flows are amplified and controlled by the turbulence intensity. Vibration frequency components unrelated to galloping increase linearly with rise in turbulence intensity.
• 4 There is a time lag of 30 s between galloping vibration and the fluctuating wind speed. The relationships between mean wind speeds and both trend components and standard deviations of galloping in turbulent flows closely correspond to those relationships during the smooth flow, and they can be obtained using the average time of 10 times the shortest vibration period of the transmission line. That is, the response values of transmission lines in the smooth flow can be utilized to estimate gallopings in turbulent flows. To estimate the maximum amplitude of a galloping, a peak factor of approximately 2.5 can be used. © 2000 Scripta Technica, Electr Eng Jpn, 131(3): 19–33, 2000