Effect of substrate on the phase transformation of TiO2 in pearlescent pigment

The TiO₂/substrate pearlescent pigments were prepared by the hydrolysis of TiOCl₂ on the substrate followed by a calcinations process. The natural mica (muscovite), synthetic mica (fluorophlogopite) and -alumina flake were selected as the substrates for pearlescent pigments. The effect of substrate on the anatase to rutile (A–R) phase transformation of TiO₂ was studied. The A–R phase transformation of TiO₂ during the preparation of pearlescent pigments and their proportion in the TiO₂ layer have been analyzed by XRD measurements. The phase compositions of TiO₂ layer in each pearlescent pigment are quite different depending on the substrates. The TiO₂ layer deposited on -alumina has higher rutile fraction than those on the natural and synthetic mica. The XPS analysis showed that the cations originally present in the substrates diffused into the TiO₂ layer. The TiO₂ layer deposited on -alumina contains Al, while those on the natural and synthetic mica substrates contain Si and K in addition to Al. The metal cations diffusing from the substrate into TiO₂ layer might retard the A–R phase transformation of TiO₂. The suppressing effect on the A–R transformation of TiO₂ by mixed cations seems to be much stronger than that of single cation, resulting in relatively higher rutile fraction in the case of TiO₂ layer deposited on -alumina.     

中国建筑的精神(上)

在揭示传统文化尚中观念形成与发展的基础上，进一步揭示《中庸》理论思维的思想文化意义；试图通过传统建筑木框架体系的形成与发展，传统建筑单体的形成与变化，传统建筑类型的分化与发展，传统建筑群体组合的变化与发展，特别是中国建筑的现代重建与发展，揭示中国建筑以人为本的尚中观念和中国建筑道不远人、高雅文化与世俗文化相融合、极高明而道中庸的人文精神。     

半自由场波叠加噪声源识别方法研究

提出了一种适合半自由场条件下进行噪声源识别的方法，通过仿真和实验验证了半自由场波叠加噪声源识别方法的正确性。根据波叠加方法的原理，声源产生的空间声场可以用其内部的一系列虚源点来等效代替，而虚源源强可以通过匹配场点的声压来获得，进而由这些虚源重建任意场点的各种声学量。通过阵列获取声压场，结果表示成声压等值线图、三维视图或声强矢量图，便于直观地判别出声源的位置、大小和传播路径。半自由场渡叠加噪声源识剐方法可以在半自由场条件下对任意形状物体进行噪声源识别。     

Kinematics, kinetics and muscle activities of the lower extremity during the first four steps from gait initiation to the steady-state walking

In this study, biomechanical characteristics during the whole process of gait initiation for twenty normal healthy volunteers were determined by the motion analysis with six near-infrared cameras, four forceplates, and an EMG system. Gait initiation, a transitional movement phenomenon from quiet stance to steady-state walking, involves a series of muscular activities, GRFs, movements of COP and COM, and joint motions. Results showed that the location of the net COP to be most lateral during double limb stance at the beginning of gait initiation. During gait initiation, changes in anteroposterior components of GRFs were first found and then changes in vertical components followed. Hip and knee motions were found before the ankle joint motion. Walking speed, step length, and stride length gradually increased until the second step. The interaction between the COM and COP is tightly regulated to control the trajectory of the COM and thereby control total body balance. This paper was recommended for publication in revised form by Associate Editor Hong Hee Yoo Sun-Woo Park received a B.S. degree in Biomedical Engineering from Yonsei University in 2006. He is currently a M.S. candidate in the Department of Biomedical Engineering, Yonsei University, Korea. His research interests in the area of Human Movement and detection of gait phase using motion sensors. Hue-Seok Choi received a B.S. degree in Computer Engineering from Daejeon University in 2004. He is currently a P.D. candidate at the Department of Biomedical Engineering at Yonsei University, Korea. His research interests are in the area of Human Movement and Rehabilitation Engineering. Ki-Hong Ryu received a B.S. and M.S. degrees in Biomedical Engineering from Yonsei University in 1998 and 2001, respectively. He is currently a P.D. candidate in the Department of Biomedical Engineering, Yonsei University, Korea. His research interests are in the area of Human Movement and Gait Training System using Functional Electrical Stimulation. Sa-Yup Kim received a B.S. degree in Electrical Engineering from Yeungnam University in 2002 and M.S. degrees in Biomedical Engineering from Yonsei University in 2006. He is currently working from Korea Institute of Industrial Technology in Cheonan, Korea. Young-Ho Kim received a B.S. degree in Mechanical Engineering from Hanyang University in 1982. He then went on to receive his M.S. and Ph.D. degrees from University of Iowa in 1989 and 1991, respectively. He is currently a Professor in the Department of Biomedical Engineering, Yonsei University, Korea. His research interests are in the area of Human Movement, Rehabilitation Engineering, and Biomechanics.     

Precipitate phases of a ferritic/martensitic 9% Cr steel for nuclear power reactors

One of the reasons that ferritic/martenstic steels have been considered as candidate materials for nuclear power reactors is their superior creep resistance at elevated temperature. The creep rupture strength of 9% chromium steel could be improved by a fine dispersion of secondary precipitate phase. The precipitate phases in extra-low carbon 9% chromium steel with tempered conditions were investigated by transmission electron microscope and energy-dispersive X-ray analysis. The steel specimens were normalized and then tempered at different temperatures. Niobium-rich MN nitrides (Nb_0.6V_0.3Cr_0.1)N, and two kinds of vanadium nitrides, (V_0.6Nb_0.2Cr_0.2)N and (V_0.45Nb_0.45Cr_0.1)N having a f.c.c. crystal structure, were identified in the steel specimens tempered at 600-780 °C, and 750 or 780 °C respectively. Hexagonal chromium-rich M₂N precipitate phases with different lattice parameters, a = 2.80 Å/c = 4.45 Å and a = 7.76 Å/c = 4.438 Å, were determined in the tempered steel specimens. The M₂N phase showed a decrease/an increase in its chromium/vanadium content as the tempering temperature was increased. The influence of precipitates and heat treatment conditions on the high temperature properties of 9% Cr steel was discussed.     

应用增广Lagrange乘子法确定裂纹应力强度因子——在RBF无网格法框架下实现

提出将增广Lagrange乘子法与RBF无网格法相结合来处理裂纹非连续性问题,从而确定裂纹应力强度因子.用径向插值基函数构造无网格形函数,基于虚裂纹扩展模式推导裂纹扩展控制方程;采用增广Lagrange乘子法处理裂纹非连续面;给出了处理裂纹非连续问题的计算列式和增广Lagrange乘子法迭代过程.通过与相关文献解比较,论证了本文方法的可靠性.     

秦皇岛32-6钻井帽在渤中25-1开发项目中使用的可行性分析

利用钻井用导管架帽 (简称钻井帽 )进行钻井作业是解决某些钻井船不能悬跨导管架钻井问题的好方案。钻井帽是临时性结构 ,使用时间即给定周期 ,一般约 1～ 2年。基于以最短的时间实现渤中 2 5 1E平台用钻井帽钻井的设想和节省工程费用的原则 ,提出用主结构尚完好的原秦皇岛 32 6钻井帽 ,在渤中 2 5 1E导管架新增底座上有限滑移 ,以满足非悬臂式钻井船渤海 5号在渤中 2 5 1E平台上钻井的要求 ,并进行了结构强度校核。经论证 ,此方案可用 ,它可缩短设计、建造周期 ,节省工程费用。     

Evaluation of Three-Dimensional Bioprinted Human Cartilage Powder Combined with Micronized Subcutaneous Adipose Tissues for the Repair of Osteochondral Defects in Beagle Dogs

Cartilage lesions are difficult to repair due to low vascular distribution and may progress into osteoarthritis. Despite numerous attempts in the past, there is no proven method to regenerate hyaline cartilage. The purpose of this study was to investigate the ability to use a 3D printed biomatrix to repair a critical size femoral chondral defect using a canine weight-bearing model. The biomatrix was comprised of human costal-derived cartilage powder, micronized adipose tissue, and fibrin glue. Bilateral femoral condyle defects were treated on 12 mature beagles staged 12 weeks apart. Four groups, one control and three experimental, were used. Animals were euthanized at 32 weeks to collect samples. Significant differences between control and experimental groups were found in both regeneration pattern and tissue composition. In results, we observed that the experimental group with the treatment with cartilage powder and adipose tissue alleviated the inflammatory response. Moreover, it was found that the MOCART score was higher, and cartilage repair was more organized than in the other groups, suggesting that a combination of cartilage powder and adipose tissue has the potential to repair cartilage with a similarity to normal cartilage. Microscopically, there was a well-defined cartilage-like structure in which the mid junction below the surface layer was surrounded by a matrix composed of collagen type I, II, and proteoglycans. MRI examination revealed significant reduction of the inflammation level and progression of a cartilage-like growth in the experimental group. This canine study suggests a promising new surgical treatment for cartilage lesions.     

Performance enhancement of ammonia-fueled engine by using dissociation catalyst for hydrogen generation

The effect of combustion of hydrogen generated by an ammonia dissociation catalyst on engine performance and exhaust emissions in a spark-ignition engine using ammonia-gasoline was investigated. An ammonia dissociation catalyst coated with 2% ruthenium on 3.175-mm alumina pellets were used in order to analyze the effect of the catalyst as an ammonia cracker to decompose ammonia into hydrogen and nitrogen. Results show that combustion of hydrogen generated by an ammonia dissociation catalyst resulted in improved engine performance and reduced exhaust emissions. The conversion rate of ammonia into hydrogen was affected by the flow rate of ammonia, and the catalyst was very effective at low to medium flow rates, resulting in significantly increased engine power and decreased fuel consumption. With the use of the catalyst, emissions of CO, HC, NH₃ and NOx were reduced considerably. Overall, it was demonstrated the ammonia dissociation catalyst can enable ammonia to be used as a hydrogen carrier for use in internal combustion engines effectively.     

Seismic Fragility of Steel Piping System Based on Pipe Size,Coupling Type,and Wall Thickness

In this study, a probabilistic framework of the damage assessment of pipelines subjected to extreme hazard scenario was developed to mitigate the risk and enhance design reliability. Nonlinear 3D finite element models of T-joint systems were developed based on experimental tests with respect to leakage detection of black iron piping systems, and a damage assessment analysis of the vulnerability of their components according to nominal pipe size, coupling type, and wall thickness under seismic wave propagations was performed. The analysis results showed the 2-inch schedule 40 threaded T-joint system to be more fragile than the others with respect to the nominal pipe sizes. As for the coupling types, the data indicated that the probability of failure of the threaded T-joint coupling was significantly higher than that of the grooved type. Finally, the seismic capacity of the schedule 40 wall thickness was weaker than that of schedule 10 in the 4-inch grooved coupling, due to the difference in the prohibition of energy dissipation. Therefore, this assessment can contribute to the damage detection and financial losses due to failure of the joint piping system in a liquid pipeline, prior to the decision-making.