Multi-Material Topology Optimization of Structures Using an Ordered Ersatz Material Model

This paper proposes a new element-based multi-material topology optimization algorithm using a single variable for minimizing compliance subject to a mass constraint.A single variable based on the normalized elemental density is used to overcome the occurrence of meaningless design variables and save computational cost.Different from the traditional material penalization scheme,the algorithm is established on the ordered ersatz material model,which linearly interpolates Young’s modulus for relaxed design variables.To achieve a multi-material design,the multiple floating projection constraints are adopted to gradually push elemental design variables to multiple discrete values.For the convergent element-based solution,the multiple level-set functions are constructed to tentatively extract the smooth interface between two adjacent materials.Some 2D and 3D numerical examples are presented to demonstrate the effectiveness of the proposed algorithm and the possible advantage of the multi-material designs over the traditional solid-void designs.

Exploring coupling coordination between urbanization and ecosystem quality （1985-2010）： a case study from Lianyungang City, China

Urbanization processes affect the ecosystem through alterations in ecological functions and landscape patterns. Currently, analysis of the total ecosystem services value （ESV） has targeted the overall benefits which human beings obtain from the regional ecosystem but does not generally include information regarding ecological struc- tures and patterns. Therefore, the results cannot reflect the comprehensive state of the local ecosystem. We propose a new, integrative ecosystem quality indicator based on the ESV and landscape metrics for evaluating the quality of the regional ecosystem. We adopted the method of a coupled degree of coordination for evaluating the interrelationship between urbanization and ecosystem quality in Lianyun- gang City from 1985 to 2010. The coupling degree of coordination between urbanization and ecosystem quality showed an inverse U-shaped curve. At the primary stage of urbanization （1985-1995）, the degree of coupling of urbanization and the ecosystem was just barely balanced. From 1995 until 2000, the coupling system reached a balanced condition, in which the urbanization level increased. Since 2000, the urbanization process has accelerated. The coordination between urbanization and the ecosystem achieved the optimum condition in 2005. A turning point appeared at the same time, and the degree of coupling coordination began falling from the optimum. Subsequently, the coupled system once more entered a barely balanced state. Overall, the comprehensive level of ecosystem quality decreased since 1985 and degraded sharply after 2005, suggesting an overall degradation of the local ecosystem quality.

Latest research progress of marine microbiological corrosion and biofouling, and new approaches of marine anti-corrosion and anti-fouling

Marine resources and industry have become one of the most important pillars in economic development all over the world.However,corrosion of materials is always the most serious problem to the infrastructure and equipment served in marine environment.Researchers have found that microbiologically influenced corrosion(MIC)and marine bio-fouling are two main mechanisms of marine corrosions due to the complicated marine environment and marine organisms.This article summarized the latest research progress about these two mechanisms and indicated that both MIC and marine bio-fouling are closely related to the biofilms on material surfaces formed by the marine microorganisms and their metabolites.As a result,to prevent the occurrence of MIC and bio-fouling,it is important to control the microorganisms in biofilms or prevent the adhesion and formation of biofilms.The traditional method of using chemical bactericide or antifoulant faces the problems of pollution and microorganism resistance.This article introduced four research approaches about the new tendency of applying new materials and technologies to cooperate with traditional chemicals to achieve better and longer effects with lower environment pollution through synergistic actions.Finally,some future research tendencies were proposed for whole marine anti-corrosion and anti-fouling areas.

How did Reefs Evolve during the Precambrian-Cambrian Transition?

Reefs are considered to be one of the most abundant and diverse niches in the marine ecosystem, and the study of the composition, distribution, and evolution of reefs over geologic time can provide important clues to understanding contemporaneous marine environmental conditions.

Analyzing the spatial patterns and drivers of ecosystem services in rapidly urbanizing Taihu Lake Basin of China

Quantifying and mapping the distribution patterns of ecosystem services can help to ascertain which services should be protected and where investments should be directed to improve synergies and reduce trade- offs. Moreover, the indicators of urbanization that affect the provision of ecosystem services must be identified to determine which approach to adopt in formulating policies related to these services. This paper presents a case study that maps the distribution of mukiple ecosystem services and analyzes the ways in which they interact. The relationship between the supply of ecosystem services and the socio-economic development in the Taihu Lake Basin of eastern China is also revealed. Results show a significant negative relationship between crop production and tourism income （p 〈 0.005） and a positive relationship between crop production, nutrient retention, and carbon sequestration （p 〈 0.005）. The negative effects of the urbanization process on providing and regulating services are also identified through a comparison of the ecosystem services in large and small cities. Regression analysis was used to compare and elucidate the relative significance of the selected urbanization factors to ecosystem services. The results indicate that urbanization level is the most substantial factor inversely correlated with crop production （R2 = 0.414） and nutrient retention services （R2 = 0.572）. Population density is the most important factor that negatively affects carbon sequestration （R2 = 0.447）. The findings of this study suggest the potential relevance of ecosystem service dynamics to urbanization management and decision making.

内源性电场调控抗菌离子传输以提高植入材料抗菌性能

组织植入材料相关感染是临床治疗的一大顽疾,基于抗菌离子释放系统的抗菌植入材料是经济高效的抗生素治疗替代手段.但过量释放的抗菌离子在杀灭细菌的同时也可能引起生物毒性.因此,如何提高释放离子的抗菌效率是急需解决的根本问题.本研究设计了一种负载低剂量抗菌离子的铁电植入材料,该植入材料表面电势可在不改变自身成份的前提下通过外源电场极化进行调控.研究发现上述铁电植入材料释放的抗菌离子将在植入材料自身与带电细菌之间形成的内源性电场作用下定向输运到达细菌.研究结果表明在12 h内,高表面电势植入材料向细菌输运的离子量达到低表面电势植入材料输运量的2.4倍,从而使抗菌效率从65%提高到100%,并展现出较低的细胞毒性.本研究表明植入材料与生命体间的内源性电场在介导物质传输中发挥重要作用,为设计高性能抗菌生物材料提供了一个新的视角.

General Definitions of Consonants and Vowels

This article discusses the definitions,classifications and features of consonants and vowels by listing different varieties of languages as examples.