An automated approach for the design of Mechanically Stabilized Earth Walls incorporating metaheuristic optimization algorithms

Considered as cost-efficient, reliable and aesthetic alternatives to the conventional retaining structures, Mechanically Stabilized Earth Walls (MSEWs) have been increasingly used in civil engineering practice over the previous decades. The design of these structures is conventionally based on engineering guidelines, requiring the use of trial and error approaches to determine the design variables. Therefore, the quality and cost effectiveness of the design is limited with the effort, intuition, and experience of the engineer while the process transpires to be time-consuming, both of which can be solved by developing automated approaches. In order to address these issues, the present study introduces a novel framework to optimize the (i) reinforcement type, (ii) length, and (iii) layout of MSEWs for minimum cost, integrating metaheuristic optimization algorithms in compliance with the Federal Highway Administration guidelines. The framework is conjoined with optimization algorithms such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Artificial Bee Colony (ABC), and Differential Evolution (DE) and tested with a set of benchmark design problems that incorporate various types of MSEWs with different heights. The results are comparatively evaluated to assess the most effective optimization algorithm and validated using a well-known MSEW analysis and design software. The outcomes indicate that the proposed framework, implemented with a powerful optimization algorithm, can effectively produce the optimum design in a matter of seconds. In this sense, DE algorithm is proposed based on the improved results over GA, PSO, and ABC.     

Learning from the West Coast: Long-Termism and Change – An Interview with Stewart Brand

Stewart Brand has been a key figure in the alternative culture of the US West Coast since the 1960s. The key message in his various publications has been that communities should be enabled to constantly reshape their own environments. In conversation with former Technical Editor of AD Peter Murray , he describes his lifestyle and influences – from the hippy movement, to time working for California Governor Jerry Brown in the 1970s, to writers such as Gregory Bateson, Frank Duffy and Christopher Alexander – and advocates a loose-fit ‘architecture of systems’, rather than a fixed and limiting ‘architecture of moulds’.     

核分析技术在环境和医学研究中的应用

通过对汽车尾气颗粒物、同一污染源的不同粒径飞灰样品的分析,以及稀土元素对人和动物的毒性研究,获得了环境监测和方面的特定信息,展现了核分析技术在环境和医学中的广泛应用。     

煤矸石和硅藻土对熔模石膏型性能的影响

向石膏中加入不同的耐火填料,在同一水膏比下,分别测试分析石膏浆料的流动性、凝结时间,石膏铸粉的湿强度、焙烧后的强度、线收缩率和显微组织。结果表明,煤矸石和硅藻土同时加入石膏粉中,焙烧后的石膏晶粒间搭接良好、紧密度高、铸型强度高。在煤矸石加入量为20%且硅藻土加入量为10%时,石膏浆料的流动直径为90mm,初凝时间为7min,终凝时间为17min,湿抗折强度为2.02MPa,抗压强度为2.3MPa,焙烧后的抗折强度为0.458MPa,抗压强度为1.07MPa,线收缩率为0.320%。     

Full scale investigation of GCL damage mechanisms in small earth dam retrofit applications under earthquake loading

This paper reports results of full scale testing to further explore potential GCL damage mechanisms in earth dam retrofit applications in seismically active areas; in particular, to a) investigate whether shear displacements could reduce the magnitude of GCL panel overlap during earthquake shaking; b) explore the influence of gravel particles on GCL thickness at localised point of contact; and c) observe the consequences of an accidental exposure of an uncovered GCL to short duration rainfall in terms of moisture content and effects during subsequent compaction. The results of these experiments indicate that even under severe shaking no movements were detected at the GCL panel overlap. Whereas gravel particles were observed to locally reduce the thickness of the GCL to 2.2 mm, no plowing of the particle into the GCL occurred due to a lack of shear displacement at the interface, resulting in no localised internal erosion through the barrier. Furthermore, hydration of GCL panels during construction due to surface wetting was observed to result in a state of hydration less than its post-construction state. These results indicate that although each of the three GCL damage mechanisms cannot be ruled out to ever be relevant in practice, the performance of the GCL retrofitted earth dam tested was satisfactory under even severe Level 2 earthquake shaking, and suggests that the retrofitting of small earth dams with GCLs is a promising strategy to improve their static and seismic resistance.     

Alkaline earth metal-based catalyst and process for selective hydrocarbon conversion to acetylene and carbon monoxide

A multi-step process that employs a Ni-modified mixed alkaline earth metal oxides (AEMO) has been developed for the selective conversion of hydrocarbons to C₂H₂ and CO. The initial process step is the catalytic decomposition of a gaseous hydrocarbon mixture at an elevated temperature (ca. 800 °C) over Ni/AEMO, generating H₂, trace CO, carbon (C), and trace alkaline earth metal carbide (MC₂). The Ni/AEMO/C/MC₂ material is then heated to consume the remaining carbon, generate more MC₂, and evolve CO. Then, Ni/AEMO/MC₂ is cooled and reacted with excess H₂O at a low temperature (20 < T (°C) < 80) to selectively generate C₂H₂ and Ni/AEM(OH)₂·zH₂O. In the final process step, Ni/AEM(OH)₂·zH₂O is decomposed to yield H₂O and Ni/AEMO, which is recycled within the process. The most advanced Ni/AEMO materials developed thus far exhibit intrinsic production capacities exceeding 2000 μmoles of C₂H₂ per gram of Ni/AEMO per process cycle.     

基于Google Earth的三维飞行仿真系统设计

提出了一种利用Google Earth二次开发能力实现飞机六自由度飞行仿真的方法,使用KML语言描述了地景中的三维参考航线和飞行姿态,将Google SketchUp建立的飞机三维模型导入到Google Earth中,通过面向对象的编程思想,利用Microsoft VC++6.0对Google Earth进行控制,实现仿真系统的人机交互功能;系统采用B/S结构,客户端采用Google Earth浏览器,全部开发都在服务器端;系统运行结果表明:该系统可逼真地模拟飞机飞行;系统还可以用于三维航迹研究分析、实时航迹监视等,具有广阔的开发前景。     

铸造铝合金精炼变质的好材料--稀土合金

讨论了稀土合金在铸造铝合金中长效变质和将精炼后的铝合金液长时间保持纯净的原理。应用稀土合金变质和精炼的工艺对环境不造成任何污染,为创造绿色集约化铸造业提供了一种极好的选择。     

稀土变质处理加热处理对低铬白口铸铁碳化物形貌及力学性能的影响

从改善低铬白口铸铁碳化物形貌出发,研究了稀土变质处理和热处理的作用。结果表明：综合运用稀土变质处理和热处理是改善低铬白口铸铁共晶碳化物形貌、提高综合力学性能的有效途径。     

MO对B2O3-Al2O3-SiO2系统玻璃析晶性能的影响

研究了添加BaO、CaO、MgO对B2O3-Al2O3-SiO2系统玻璃析晶性能的影响。用DSC测试了玻璃的析晶温度，用XRD分析了玻璃析晶后的晶相组成，用SEM观察了析出晶粒的形貌特征。结果表明：BaO、CaO均可有效促进BAS玻璃的形成，而MgO易导致玻璃分相。MO-BAS玻璃的析晶温度在770～810℃之间。添加BaO时析出的主晶相为硼酸铝（Al18B4O33）和少量勃来石（Al16B6Si2O37），以针柱状晶为主。用CaO替代BaO，析出的主晶相不变，但析晶能力增加，以细小的粒状晶为主。添加MgO时析出的主晶相为偏硼酸铝（Al4B2O9）和勃来石，晶粒较粗大。