中型机库结构设计

以海航维修机库和河北航维修机库为例,对中型机库的结构设计进行了系统的阐述,重点介绍了结构选型布置、受力特点及设计优化,以及不同工况的计算分析。对两个机库附房与机库大厅设置防震缝与不设置防震缝方案的计算分析表明,当中型机库设置有门库时,附房与机库大厅间可不设置防震缝。对几种结构方案的经济指标分析表明,一般中型机库采用空间钢网架屋盖结构体系较为经济合理。     

大型承重保温夹芯复合墙体的材料选型及模拟

针对中国夏热冬暖地区居住建筑节能的要求,选定适合的结构层和保温层材料以及平行板式的复合结构,利用有限元分析法,对以陶粒混凝土为结构层、泡沫混凝土为保温层,无拉接件的保温夹芯复合墙体进行了模拟研究,提出承重保温夹芯复合墙体在竖向荷载和风荷载作用下各种应力分布的基本规律为：竖向荷载下复合墙体的压力主要由结构层承担,压应力呈现出沿板宽度的两端较大而中间部位较小的马鞍形分布,且底部两端的压应力较大;在竖向10MPa荷载作用下结构层压应力的理论计算值为15MPa,保温层的抗压强度大于021MPa;在风荷载作用下,结构层与保温层间的界面切应力随墙体高度变化均呈双峰型分布,底部及顶部均为0,中间部位接近0,在它们之间出现峰值,界面切应力最大值为389kN/m2,界面正应力最大值为139kN/m2.     

减少沥青路面横向裂缝的措施

随着交通量不断增长,车辆重载、超载现象日益严重。沥青路面通车一段时间后,常常出现不同程度的横向裂缝。分析了沥青路面横向裂缝产生的原因和危害,同时提出了相应的裂缝防治措施。     

株洲市中心医院的结构设计

较详细地介绍了株洲市中心医院结构的设计过程,包括基础选型,超长地下室,钢结构屋盖设计,以及医疗设备用房相关的荷载取值,防辐射,直线加速器室,高压氧舱的设计要点等,相关设计方法可供同类项目参考。     

Compression and filtration characteristics of yeast-immobilized beads prepared using different calcium concentrations

Yeast cells were immobilized on calcium alginate beads prepared using different calcium concentrations. The compression properties of the immobilized beads (e.g., softness index and retardation time for compression) were strongly affected by the calcium concentration. The effects of the bead properties on filtration characteristics, such as cake porosity, specific cake filtration resistance, cake compression creeping effect and cake compressibility, were analysed using a dead-end filtration system. The filtration curve of yeast-immobilized beads had an “S” shape, similar to that of soft gel particles. The cake compression behaviour and variation in cake properties were directly reflected on the curve trend. The Voigt in the series model was employed to describe variation in cake porosity with time during a compression. The yeast immobilization increased the bead softness; therefore, the porosity of a cake formed by yeast-immobilized beads was lower than that formed by pure calcium alginate beads. The cakes formed by yeast-immobilized beads possessed a high compressibility of approximately 1.0 and a high softness index of approximately 1.5. The beads prepared using lower calcium concentrations had higher softness, shorter retardation times for compression, higher cake compressibility, lower cake porosity and higher specific cake filtration resistance. The results demonstrated that immobilizing yeast cells on calcium alginate beads is beneficial for retaining higher yeast activity than that of freely suspended yeast. However, the activity levels of yeast immobilized using different calcium concentrations were nearly the same after 3 h. Therefore, using high concentrations of calcium for yeast immobilization is beneficial for improving yeast activity and filtration characteristics.     

Fabrication of super‐ductile PP/LDPE blended parts with a chemical blowing agent

The mechanical blending of polypropylene (PP) and low density polyethylene (LDPE) is an economical and simple method for producing new polymeric materials for specific applications. However, the reduction in strain‐at‐break of the blend is one of its main shortcomings. In this study, PP/LDPE foamed parts were fabricated by conventional injection molding (CIM) with azodicarbonamide as a chemical blowing agent (CBA) and tested for tensile properties at two test speeds. Also, the fracture surfaces of the parts were investigated by scanning electron microscopy (SEM). In addition, to investigate the underlying mechanism of the super‐ductility, the tested samples were carefully analyzed and compared, and further characterized by differential scanning calorimetry and SEM. The results suggest that fabricating PP/LDPE super‐ductile parts using CIM with a CBA is feasible. The results also indicate that there is a close relationship between the mechanical properties and morphological structures, which are deeply influenced by the dosage of CBA, the PP/LDPE ratio, and the packing parameters. Furthermore, compared to conventional injection molded solid parts, the ductility of the foamed parts can be dramatically improved by the formation of microfibrils in the PP phase, which come into being under certain processing conditions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44101.     

Thermoplastic rubber/PP elastomers toward extremely low thermal expansion

Fine regulation of the microstructure of rubber/polypropylene (PP) alloys could remarkably reduce the coefficient of linear thermal expansion (CLTE) while retaining the mechanical properties similar to those of thermoplastic elastomers. Rubber/PP elastomers with different morphologies were successfully prepared by controlling the appropriate rubber type, viscosity ratio, and processing method. The CLTE of the polymer alloy parallel to the microlayer directions was considerably reduced when the rubber domains were deformed into microlayers and co‐continuous with plastic domains. The thickness of the PP layers played a crucial role on CLTE reduction. The CLTE considerably decreased with reduced thickness of the PP layer. The sample with a co‐continuous microlayer structure exhibited good flexibility, high elongation, low hardness, and permanent deformation. Thus, low‐thermal‐expansion elastomer materials may have wide applications. Stress relaxation and strain recovery of the ethylene–propylene–diene terpolymer/PP (70/30 wt %) blend were investigated to further clarify the influence of co‐continuous microlayer structure on mechanical properties. Anisotropic mechanical properties were consistent with the morphology. Results of the stress relaxation behavior test would provide further support to the mechanism of the low thermal expansion of blends with co‐continuous microlayer structure. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43902.     

Fast access to core/shell/shell CdTe/CdSe/ZnO quantum dots via magnetic hyperthermia method

The intrinsic low quantum yield (QY) of type II core shell quantum dots (QDs) composes the limitation for these heterostructured nanomaterials to be used in practical application. Herein, magnetic hyperthermia method is employed to intensify reaction process and facilely synthesize CdTe/CdSe heterostructured QDs with improved optical performance for the first time. The QY of the type II QDs is increased to 49% by further growing an inert ZnO layer. The type I interface between CdSe and ZnO helps confine electrons to the inner structure of the QDs, thus improving the QY. The successful preparation and performance enhancement of the CdTe/CdSe type II QDs via magnetic hyperthermia method demonstrate the great potential of this method for the preparation of other materials. Besides, the red‐emission QDs are used as conversion materials in white light emitting diodes to reveal their promising application in practical illumination. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2614–2621, 2016     

Effects of K2O Evaporation on the Structural Properties of KSbO3 Compounds

A specimen having a stoichiometric composition of KSbO₃·(KSb) calcined at 800°C has an R rhombohedral structure (RS), and changes to a Pn cubic structure (CS) when calcined at 1100°C. Finally, a <111>‐oriented rhombohedral phase is formed in the specimen calcined at 1230°C. K/Sb ratio decreases from 1.0 in RS, 0.93 in CS, and finally to 0.85 in <111>‐oriented rhombohedral phases. On the other hand, a specimen having a K‐excess composition of K_1.1SbO₃ calcined at 800°C shows a RS that is maintained in the K‐excess specimen calcined at 1230°C. The composition of these specimens is very close to KSb. Therefore, the RS with a space group of R is a stable form of KSbO₃. The formation of Pn cubic and <111>‐oriented R phases can be explained by the evaporation of K₂O during the calcination process at temperatures above 1100°C.