On the formation mechanisms of fine granular area (FGA) on the fracture surface for high strength steels in the VHCF regime

The fine granular area (FGA) plays a crucial role in the VHCF regime. However, so far, the uniform understanding or conclusion about the formation mechanism of FGA has not been drawn. In view of the significance of FGA, the current studies on FGA, i.e., the FGA size, the stress intensity factor range at the periphery of FGA, the crack initiation and growth process in FGA, and the formation mechanisms of FGA, are reviewed in the present paper. The role of internal hydrogen in the VHCF regime is further discussed. In the end, two important definite conclusions are drawn based on the present investigations.     

一种新柱式

文章介绍了在计算机的帮助下产生的一种全新的柱式。它基于一种基本的折叠手法,其结果所呈现的极其丰富的细节超越了传统cAD工具能够绘制的极限,也超越了肉眼所能观察的极限。这些出乎意料的形式与极其微小的细节来自计算机程序的反复迭代,它们超出了建筑师的经验、教育和历史认知,无论从手法还是结果来看,都是一种彻底的创新。文章还指出,建造如此复杂的细节需要现代化的数字加工技术与独特的加工技巧。     

Linear friction welding of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy with dissimilar microstructure

Dissimilar linear friction welding of Ti–5Al–2Sn–2Zr–4Mo–4Cr with bimodal and lamellar microstructures was produced. The microstructure evolution of the joint was investigated via OM, SEM, XRD, TEM and microhardness analysis. The temperature field of joint was calculated by a numerical model. The typical microstructures of weld center were recrystallized β grains with some acicular α′′ martensites. In the case of thermo-mechanically affected zone, some partial re-crystallization grains formed in severely deformed microstructures, where a mass of dislocations were observed. However, dislocations were rarely found in the recrystallized β grains of weld center, the temperature field of weld joints calculated was consistent with the microstructural evolution.     

The microstructure evolution and mechanical properties of MgO-C refractories with recycling Si/SiC solid waste from photovoltaic industry

In the present work, the recycling of Si/SiC solid waste from photovoltaic industry for MgO-C refractories preparation has been introduced. The influence of solid waste powders as antioxidant additive on microstructure evolution, mechanical properties and thermal shock resistance of MgO-C refractories has been investigated systematically. With 4?wt% Si/SiC rich solid waste addition, the MgO-C refractories exhibited the highest strength (4.39?MPa) and residual Young's modulus (7.86?GPa) after firing at 1400?°C, compared to only Si or SiC-addition. The presence of iron in the solid waste also promoted the formation of MgO and Mg₂SiO₄ whiskers via catalyst-assisted method. Moreover, a dissolution-saturation-precipitation growth mechanism was used to explain the formation process of the whiskers. The improvements in strength as well as thermal shock resistance can be attributed to the microstructural evolution.     

Formation of the spherical reticulated mega-structure and its stabilities in construction

The spherical reticulated mega-structure, an innovative structure, is presented and studied in this paper. The formation method, form parameters and support style are first investigated. Based on the traditional construction methods of spatial structure, the feasible construction and erection method of this kind of structure is analyzed, and different erection sequences of the structure as well as the settings of temporary supports are proposed. The stabilities of the structure in the process of erection are then studied by both linear and nonlinear methods in detail. The effective settings of the temporary supports and reasonable erection sequence of the substructures are obtained, and some recommendations on erection are presented. This work will provide guidance in theory for construction and erection of this kind of structure.     

Description and Phylogenetic Position of Dinosaur Eggshells from the Luanchuan Area of Western Henan Province, China

Here, we examine 145 dinosaur eggshells from a new fossil locality in the Qiupa Formation (Upper Cretaceous) of the Luanchuan area in western Henan Province, China. The eggshells display elongatoolithid macro- and microstructures, including ridges and nodes on the outer surface, two ultrastrncturai layers, and an undulatory boundary between the mammiilary and continuous layers.A phylogenic analysis shows that the Luanchuan eggshells belong to the ooclade Eiongatoolithidae.Within Elongatoolithidae, the thickness ratio of the mammillary layer to the entire eggshell, and the porosity of the Luanchuan eggshells are comparable to the oogenera Macroolithus and Elongatoolithus. There is no direct evidence for the taxonomic identity of the Luanchuan eggshells;however, they were likely laid by oviraptorids based on their phyiogenetic position and their similarities with known oviraptorid eggs.     

珠江口盆地东沙隆起珠江组沉积环境及演化

珠江口盆地东沙隆起是重要的油气勘探领域.通过对珠江口盆地东沙隆起的岩心观察描述和岩石薄片鉴定,确认其主要的岩石类型及生物组合,结合地震、测井、录井资料,将珠江口盆地东沙隆起珠江组划分为开阔台地相、台地边缘相、台地前缘斜坡相、海滩相、陆棚相5个沉积相,并进一步划分出9个亚相及若干微相.在此基础上,讨论珠江组沉积相空问展布...