Wet shells and dry tales: the evolutionary ‘Just-So’ stories behind the structure–function of biominerals

The ability of evolution to shape organic form involves the interactions of multiple systems of constraints, including fabrication, phylogeny and function. The tendency to place function above everything else has characterized some of the historical biological literature as a series of ‘Just-So’ stories that provided untested explanations for individual features of an organism. A similar tendency occurs in biomaterials research, where features for which a mechanical function can be postulated are treated as an adaptation. Moreover, functional adaptation of an entire structure is often discussed based on the local characterization of specimens kept in conditions that are far from those in which they evolved. In this work, environmental- and frequency-dependent mechanical characterization of the shells of two cephalopods, Nautilus pompilius and Argonauta argo, is used to demonstrate the importance of multi-scale environmentally controlled characterization of biogenic materials. We uncover two mechanistically independent strategies to achieve deformable, stiff, strong and tough highly mineralized structures. These results are then used to critique interpretations of adaptation in the literature. By integrating the hierarchical nature of biological structures and the environment in which they exist, biomaterials testing can be a powerful tool for generating functional hypotheses that should be informed by how these structures are fabricated and their evolutionary history.     

青西油田的裂缝特征

本文从岩心和测井资料出发,研究酒泉盆地青西油田裂缝的类型和微观特征,通过区域构造背景和断裂特征分析,研究裂缝分布规律及与构造的关系,进而应用地震属性分析,结合钻井和测井资料对裂缝进行预测,得出以下认识:①下白垩统下沟组块状砂砾岩和泥质白云岩为典型的特低孔、低渗储层,裂缝为最主要的油气储集空间和运移通道,各种类型构造裂缝均有发育,但高角度裂缝和斜交缝对油气富集最为有效;②断层控制了裂缝的发育方向,裂缝发育带展布方向和断裂发育带展布方向基本一致,主要为北北东向和北西西向;③构造转折部位和断层交会带为构造应力集中的部位,裂缝发育;④裂缝的发育程度控制了油气的富集程度,北北东向调节断层产生的裂缝带是油气富集带。结合裂缝预测结果,在青西油田部署的L104井获得64m3/d的高产工业油流。     

多属性微断裂解释技术

四川盆地九龙山地区侏罗系珍珠冲组砾岩段气藏为构造—岩性气藏,受构造、储层、裂缝等多因素控制,并受地震资料品质和解释思路的影响,应用地震剖面、常规相干体切片不能对微断裂进行精细刻画。文中在构造导向滤波的基础上联合运用谱分解、新一代相干体切片和体曲率技术,精细刻画了微断裂的空间展布规律,说明多属性微断裂识别技术是可靠的断裂识别手段,其中体曲率属性对断层及微断裂的刻画更为清晰。野外地质考察及最新钻、测井资料的验证结果表明,珍珠冲组砾岩段微断裂十分发育,以北东、北西向为主。     

兴西洼陷沙四段近岸水下扇的识别

兴西洼陷是一个位于辽西凹陷中段的狭长沉积构造,以往大多认为该区沙四段地层不发育,从而制约了该区油气勘探的深化。本文通过对兴西洼陷的地震层位进行对比,落实了该区的最有利储层———沙四段。综合分析区域构造背景和沉积特点,认为该区存在东部陡坡带控制下的近岸沉积扇体;运用多种物探技术手段预测和刻画了一系列近岸水下扇储集体。部署在该区的兴西2井成功揭示了沙四段近岸沉积扇体的存在,并喜获工业油流,打开了该区的油气勘探局面。     

基于等效时间的早期混凝土温度裂缝分析

基于等效时间的混凝土绝热温升、热传导方程，考虑温度对早期混凝土水化热化学反应速率和徐变特性的影响，计算了大体积混凝土墙中心的温升。采用裂缝带模型计算温度裂缝，用半解析迭代法进行了混凝土墙的温度应力和开裂计算。     

基于引力场的基坑悬臂式支挡结构设计与实践

基坑工程的质量依赖于科学合理的基坑设计、详细周密的地质勘察、精心细致的施工作业、可靠有效的实时监测。基坑工程的支护形式多种多样,悬臂式支挡结构就是其中之一,目前尚没有人能对悬臂式支挡结构确切的工作机理给出一个令人满意的解释,悬臂式支挡结构在坑底以下的嵌固深度计算也缺少可靠的理论公式,因此导致悬臂式支挡结构出现事故的现象时有发生,因此悬臂式支挡结构嵌固深度的合理确定就成了悬臂式支挡结构成功与否的关键。以长年的基坑工程实践与理论研究为基础,结合地球引力场理论,对悬臂式支挡结构确切的工作机理作出一个比较切合实际的解释,指出了支挡结构底部与接触岩土体间的摩擦力对悬臂式支挡结构稳定的关键作用,给出了悬臂式支挡结构嵌固深度计算的理论公式和工程实例。     

Evolution of RFIC Handset PAs

The first official shift in communication systems from fixed-location devices to portable/mobile devices happened in 1973 when Martin Cooper, general manager of Motorola's Communications Systems Division at the time, placed the first mobile call from a New York street using AT&T's network. Four years later, the first cell phone was made in Chicago with free trials offered to more than 2,000 people. The first commercial handset to receive FCC approval was Motorola's DynaTAC in 1983 [1], which was made available to the public a year later. This 1.13 kg (2.5 lb) phone that cost consumers US$3,500 was only able to achieve approximately 35 minutes of talk time and took almost 15 years to develop with the cost totaling US$100 million.     

Factor structure of the BASC-2 Behavioral and Emotional Screening System Student Form: Correction to Dowdy et al. (2011).

Reports an error in Factor structure of the BASC–2 Behavioral and Emotional Screening System Student Form by E. Dowdy, et al. (Psychological Assessment. np). There was an omission in the author note. The author note should have included a disclosure as follows, “Randy W. Kamphaus wishes to disclose a potential conflict of interest in that he receives a portion of royalties on net sales of BESS.” (The following abstract of the original article appeared in record 2011-04578-001.) The BASC–2 Behavioral and Emotional Screening System (BESS) Student Form (Kamphaus & Reynolds, 2007) is a recently developed youth self-report rating scale designed to identify students at risk for behavioral and emotional problems. The BESS Student Form was derived from the Behavior Assessment System for Children—Second Edition Self-Report of Personality (BASC–2 SRP; Reynolds & Kamphaus, 2004) using principal component analytic procedures and theoretical considerations. Using 3 samples, the authors conducted exploratory factor analyses (EFA) and confirmatory factor analyses (CFA) to understand the underlying factor structure of the BESS Student Form. The results of the EFA suggested that the SRP contained a 4-factor (i.e., Personal Adjustment, Inattention/Hyperactivity, Internalizing, School Problems) emergent structure, which was supported by CFA in 2 additional samples. Practical and research implications are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Low Complexity Antenna Selection Scheme for Multicarrier MIMO Broadcast Communication

A low complexity antenna selection scheme for multicarrier MIMO (Multiple Input Multiple Output) broadcast systems is proposed in this paper. Under special condition of single user in the system or when the number of subcarrier is only one, the system reduces to conventional MIMO-OFDM (Orthogonal Frequency Division Multiplexing) system or MIMO-BC (Broadcast Channel) system respectively. By analysing sub-optimal antenna selection schemes developed earlier for single user MIMO-OFDM systems and single carrier MIMO-BC systems, one can see many similarities which can be extended to multicarrier MIMO broadcast systems. The proposed method exploits these similarities to obtain a low complexity system design with acceptable performance. The performance of the proposed scheme is studied via extensive simulation, and the computational complexity involved is compared to the conventional scheme. A selection gain of approximately 0.5 b/s/Hz is shown to be achievable using only two out of three antennas, and the proposed scheme is able to achieve up to 90% of the gain. This is achieved at a complexity that is significantly lower than the conventional methods, hence the practical implementation of the proposed scheme can be justified.     

From Biomimetic Concept to Engineering Reality – A Case Study on the Design of Ceramic Reinforcement

The applications of ceramics are limited by their brittleness. Though the toughness of ceramics can be improved by adding hard and strong toughening agents, their damage tolerance is still poor. Novel concept derives from fish scale is explored and used to design alternative toughening agent. The microstructure of fish scale exhibits hierarchical complexity and many weak layers are present. As fish scales are used directly as the toughening agent, the toughness of ceramics can be enhanced. Furthermore, a new toughening mechanism involving crack deflection within fish scale is observed. Based on such observation, the toughening agents with internal weak interfaces are recommended as the toughening agent. Many ceramic/metal interfaces are present within the multilayer ceramic capacitors (MLCCs). The addition of MLCCs into brittle glass improves its crack resistance considerably.