Finite element analysis for the structure of large crystallizer

Crystallizer is a key equipment of the 1.2 million tons production line. It is a complicated shell structure and a large but thin machine. The power mixing process is a typical property of the crystallizer. So the structure reliability and the modal of crystallizer should be analyzed. The structure strength, safety coefficient and multi modal are analyzed by COSMOS which is large scale finite element software. The results show that the static strength of the support part meets the requirement, the weakest part of the crystallizer is the weld point, the steel beam with the equivalent stress is 260 MPa, safety coefficient is 1.243 and the stability of crystallizer main structure under dynamic disturbance meets the requirements, thus resonance doesn’t occur.     

非线性Mohr-Coulomb破坏准则下边坡可靠度上限

传统边坡可靠度分析往往在岩土参数服从线性Mohr-Coulomb（简称线性M-C）破坏准则的假设条件下进行,并且常常采用极限平衡法或有限元法计算安全系数。然而,岩土介质破坏准则具有一定的非线性。为能更加实际地描述岩土破坏机理和得到严格精确的解,基于非线性Mohr-Coulomb（简称非线性M-C）破坏准则,结合极限分析上限法和蒙特卡洛法,进行边坡可靠度上限分析。当非线性参数m=1时,与等效的线性M-C破坏准则进行对比计算,验证了方法的可行性。同时,将初始粘聚力、内摩擦角arctan（c₀/σ_t）和非线性参数作为随机变量且服从截断正态分布,进行了参数变异性和敏感性影响分析。研究表明：非线性M-C破坏准则下,边坡可靠度随初始粘聚力、内摩擦角arctan（c₀/σ_t）和非线性参数变异性的增大而减小;边坡可靠度随初始粘聚力和内摩擦角arctan（c₀/σ_t）的增大而增大,随非线性参数的增大而减小。     

Characteristic analysis and risk assessment of heavy metal pollution in Liangtan river, a tributary of Three Gorges Reservoir area

Surface water samples are collected throughout the upstream Liangtan River in December, 2010. The concentrations of Cu, Zn, Ni, Pb, Cr and Fe, Mn, Mg are determined using atomic absorption spectrometry (AAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES) respectively for the contamination characteristics analysis and preliminary risk assessment. The results demonstrate that concentrations of 8 heavy metals show significant differences in different sampling sections of the river. The average concentration of Ni, Pb, Fe and Mn are much higher than the limits value of GB 3838-2002 Ⅲ functional area and their section of over standard are 100%, 87.5%, 50% and 43.75%, respectively. Spatial distribution and correlation analysis reveal that Fe and Mn in river may have the same pollution sources. Preliminary health risk assessment results indicate that Pb is the most important pollutant leading to non-carcinogenic concerns in particular for children, and the next is Cr. Mn, Ni, Cu, Fe and Zn in sequence.     

POD analysis of flow structures in thermally stratified flow in a confined space with the effects of horizontal wind

PIV measurements are carried out on the thermally stratified flows under different horizontal shear intensities in a confined space. Proper orthogonal decomposition (POD) is used to analyze the structures of these thermally stratified flows. Results show that, at the conditions without forced horizontal airflow, the low-order POD mode constitutes a high proportion of the total energy of the flow, and the horizontal flow is the dominant flow structure. The horizontal shear drives the energy to dissipate from large structure to smaller structures. Relative to the conditions without forced horizontal airflow, the ratios of vertical kinetic energy to horizontal kinetic energy become higher for each order of POD mode in the conditions with forced horizontal airflow. This indicates that horizontal shear can result in stratification instability and enhance the mass exchange in the vertical direction.     

QTL analysis for cooking traits of super rice with a high‐density SNP genetic map and fine mapping of a novel boiled grain length locus

Hybrid rice has contributed substantially to the improvement of grain production worldwide, yet its poor cooking and tasting characteristics have long been recognized. In this study, 132 recombinant inbred lines derived from LYPJ were used to identify quantitative trait loci (QTLs) for 12 cooking traits with the high‐density SNP linkage map recently developed by our team. We identified 17 QTLs on chromosomes 1, 2, 4, 5, 6, 7, 8, 9 and 11, which accounted for 7.50% to 23.50% of the phenotypic variations. A novel major QTL qBGL7 for boiled grain length was further fine‐mapped to an interval of 440 Kb between the two markers RM21906 and gl3 using a BC₃F₂ population. Two near‐isogenic lines with extreme boiled grain length, GX5‐176 and GX5‐101, could be directly used in improving cooking quality. We also identified a QTL for soaked grain width expansion rate, qSGWE6, in the Wx gene region on chromosome 6. The Wx differential regulation coincided with sequential variation between the two parents. Our work offered a theoretical basis for molecular breeding of high‐quality hybrid rice.     

Revival of a well-known, but ignored correction term for χ2 in linkage analysis with small samples

The ‘classical’χ² test is routinely applied in linkage analysis. The values customarily used, however, are only approximations since continuous χ² terms are used instead of discrete multinomial terms. This error becomes increasingly important as the sample becomes small. In this note, a well-known correction term for improvement of this approximation is revived and numerically calculated for some interesting cases from linkage studies.