Support-induced restraint effect of thin-walled tube in a steam generator subjected to combined pressure and bending load

The restraint effects of support plates on limit load (LL) are evaluated for thin-walled tubes subjected to combined internal pressure and bending loads. To achieve this goal, three-dimensional (3D) finite element (FE) analyses assuming elastic-perfectly plastic material behaviour are carried out for tubes with various sizes of circumferential cracks. Two crack locations, both the top of the tube sheet (TTS) and transition regions, where circumferential cracks have been found in many steam generators during operation, are considered. FE analysis results show that LLs for the circumferential cracks are significantly affected by the boundary conditions of the tube and that the resulting LL solutions can be simply applied to the practical integrity assessment of steam generator tubes, because the comparison between experimental data and FE analysis results shows a good agreement.     

Freezing Time Modeling for Small Finite Cylindrical Shaped Foodstuff

A model was developed consisting of a modified Plank's equation to estimate phase change time and two unsteady state cross-product heat transfer equations for estimating precooling and tempering times. It accurately predicted total time to proceed from an initial temperature above the freezing point to a final temperature of ?18°C. A correction factor was developed and incorporated in the P term in Plank's equation to correct for the effect of initial and freezer medium temperatures and heat transfer coefficients. The model, tested over a broad range of freezing conditions, had a mean absolute error of 5.9% in predicted values relative to experimental values.     

PHYSICAL,CHEMICAL, and THERMAL CHARACTERIZATION of WHEAT FLOUR MILLING COPRODUCTS1,2

Hard red winter (HRW) and hard red spring (HRS) wheat milling coproducts (bran, germ, shorts, and red dog) from three commercial flour mills and the Kansas State University pilot mill were evaluated for differences in physical, chemical, and thermal properties. the ranges of bulk density for bran, germ, and red dog determined at three moisture levels were 146.5 to 205.2 kgm^?3, 269.2 to 400.6 kgm^?3, and 298.9 to 398.1 kgm^?3, respectively. the true density ranking order was: red dog >shorts = germ >bran, independently of the moisture level. Red dog had the smallest geometrical mean diameter with the highest variation (coefficient of variation of 23.8%). There was a significant (P < 0.05) difference among wheat blends and milling flows in the thickness of bran and germ at the same particle separation size. the image analysis study determined that the equivalent projected area diameter of bran at the same separation size was significantly (P < 0.05) larger than that of germ. the ratio between the equivalent projected area diameter and the particle thickness were within ranges of 15.7 to 37.6 for bran and 15.5 to 32.2 for germ particles. the chemical composition (ash, protein, lipids and fiber) ranges were determined for each coproduct. Ranges of thermal conductivity for bran, germ, shorts, and red dog were 0.049 to 0.074, 0.054 to 0.0907, 0.057 to 0.076, and 0.063 to 0.080 W(mK)^?1, respectively. Specific heat of coproducts, measured with a differential scanning calorimeter, exhibited a wider range [1.08–1.94 kJ(kgK)^?1] than that observed in whole wheat kernels and wheat flour. the variability observed among the samples was due to the different wheat sources and characteristic milling flows for the flour mills.     

Zn_4B_6O_(13)∶Eu~(3+)的合成与光致发光

用高温固相扩散方法首次合成了由Eu3 + 离子激活的Zn4B6O13 红色光致发光材料。用XRD分析了样品结构 ,结果表明 :Zn3 .94B6O13 ∶Eu3 + 为立方晶系 ,晶胞参数a =0 .7471nm ,V =0 .4170nm3 。研究了Eu3 + 在Zn4B6O13 中的强激发带位于 3 94nm ,主要发射峰位于610nm归属Eu3 + 离子的5D0 →7F2 电偶极跃迁发射 ,根据发射光谱计算色坐标为x =0 .2 81,y =0 .619。SEM摄取了样品的清晰晶体外貌 ,平均颗粒度为 15 μm左右。加入一定量助熔剂使发射光谱的相对发射强度增加了 2 .3 2～ 3 .86倍。     

On-board handling and freezing of the sea scallop, Placopecten magellanicus

The effects of on-board handling and freezing on the quality of meats from the sea scallop, Placopecten magellanicus , in the Atlantic Canadian fishery were investigated. The results show that meats frozen within 6 h of catching, pre-rigor, were markedly superior to meats frozen after storage in ice for up to 10 days, with lower drip loss, more tender texture, less flavour loss and higher overall acceptability.
Inferior results were obtained without pre-chilling of the meats before storage in cotton bags in melting ice and with live holding for 3 days followed by freezing and storage at minus 30°C for up to 6 months. Days in ice before freezing, however, exerted by far the greatest influence on quality.
According to these results, freezing on board warrants consideration on grounds of superior quality including increased yield of cooked product.