A simplified physically-based breach model for a high concrete-faced rockfill dam: A case study

A simplified physically-based model was developed to simulate the breaching process of the Gouhou concrete-faced rockfill dam (CFRD), which is the only breach case of a high CFRD in the world. Considering the dam height, a hydraulic method was chosen to simulate the initial scour position on the downstream slope, with the steepening of the downstream slope taken into account; a headcut erosion formula was adopted to simulate the backward erosion as well. The moment equilibrium method was utilized to calculate the ultimate length of a concrete slab under its self-weight and water loads. The calculated results of the Gouhou CFRD breach case show that the proposed model provides reasonable peak breach flow, final breach width, and failure time, with relative errors less than 15% as compared with the measured data. Sensitivity studies show that the outputs of the proposed model are more or less sensitive to different parameters. Three typical parametric models were compared with the proposed model, and the comparison demonstrates that the proposed physically-based breach model performs better and provides more detailed results than the parametric models.     

Charging strategy through analysis of charging influence factors of ultra-light hydrogen storage with polyethylene terephthalate liner

A lightweight type 4 vessel with a polyethylene terephthalate (PET) liner is analyzed. The derived heat transfer coefficients between the gas and wall are applied, and a parametric study is performed. An optimized charging strategy is also developed. Firstly, when the injected hydrogen temperature decreases, the charging time increases, and the charged gas temperature decreases. Secondly, the higher the ambient temperature, the shorter the charging time, and the higher the charged gas temperature. Thirdly, the larger the mass flow rate, the shorter the charging time, and the higher charged gas temperature. Fourthly, as the initial pressure inside the vessel increases, the charging time shortens, and the charged gas temperature decreases. Fifthly, using the formulated charging strategy, during summer, the charged gas temperature decreases by approximately 9 °C. In winter, the charging time is reduced by approximately 58 s. The results provide important information of temperature control for ensuring vessel safety.     

BIM-to-IGA: A fully automatic design-through-analysis workflow for segmented tunnel linings

Both planning and design phase of large infrastructural project require analysis, modelling, visualization, and numerical analysis. To perform these tasks, different tools such as Building Information Modelling (BIM) and numerical analysis software are commonly employed. However, in current tunnel engineering practice, there are no systematic solutions for the exchange between design and analysis models, and these tasks usually involve manual and error-prone model generation, setup and update. In this paper, focussing on tunnelling engineering, we demonstrate a systematic and versatile approach to efficiently generate a tunnel design and analyse the lining in different practical scenarios. To this end, a BIM-based approach is developed, which connects a user-friendly industry-standard BIM software with effective simulation tools for high-performance computing. A fully automatized design-through-analysis workflow solution for segmented tunnel lining is developed based on a fully parametric design model and an isogeometric analysis software, connected through an interface implemented with a Revit plugin. The IGA-Revit interface implements a reconstruction algorithm based on sweeping teachnique to construct trivariate NURBS lining segment geometry, which avoids the burden to deal with trimmed geometries.     

Data-driven parameterization of polymer electrolyte membrane fuel cell models via simultaneous local linear structured state space identification

In order to mitigate the degradation and prolong the lifetime of polymer electrolyte membrane fuel cells, advanced, model-based control strategies are becoming indispensable. Thereby, the availability of accurate yet computationally efficient fuel cell models is of crucial importance. Associated with this is the need to efficiently parameterize a given model to a concise and cost-effective experimental data set. A challenging task due to the large number of unknown parameters and the resulting complex optimization problem. In this work, a parameterization scheme based on the simultaneous estimation of multiple structured state space models, obtained by analytic linearization of a candidate fuel cell stack model, is proposed. These local linear models have the advantage of high computational efficiency, regaining the desired flexibility required for the typically iterative task of model parameterization. Due to the analytic derivation of the local linear models, the relation to the original parameters of the non-linear model is retained. Furthermore, the local linear models enable a straight-forward parameter significance and identifiability analysis with respect to experimental data. The proposed method is demonstrated using experimental data from a 30 kW commercial polymer electrolyte membrane fuel cell stack.     

A study of the load transfer behavior of fully grouted rock bolts with analytical modelling

Fully grouted rock bolts have been used in mining industry for many years. Much research has been conducted to evaluate the load transfer behavior of fully grouted rock bolts with experimental programs.However, compared with that, less work has been conducted with analytical modelling. Therefore, in this paper, the authors used an analytical model to study the load transfer behavior of fully grouted rock bolts.To confirm the credibility of this analytical model, an in-situ pull-out test was used to validate this model.There was a close match between the experimental result and the analytical result. Following it, a parametric study was conducted with this analytical model. The influence of coefficients, Young's modulus of the rock bolt and the diameter of the rock bolt on the load transfer performance of rock bolts was studied.Furthermore, the load distribution along the fully grouted rock bolt was analytically studied. The results show that the axial load in the rock bolt decayed from the loaded end to the free end independent of the pull-out load. However, the trend of the load distribution curve was influenced by the pull-out load. This paper was beneficial for better understanding the load transfer mechanism of fully grouted rock bolts.     

Identification of hydrogen permeability parameters of membrane materials in an aggregated experiment

The study of the hydrogen permeability of materials for membrane-based separation/purification technologies employs a variety of experimental methods with their own specific features, advantages and shortfalls. The method of penetration with vacuum pumping allows determining the diffusion coefficient from so-called lag time. The accuracy of the estimation depends on the degree of proximity to the DLR (diffusion limited regime) mode. The method of “communicating vessels” is more sensitive to surface processes. The thermal desorption (TDS) technique permits “scanning” the material dynamically across a wide range of temperatures. “Separate” application of these methods leads to a situation where the materials studied are in fact somewhat different (for example, due to different impacts on the surface), and significant differences in parameter estimates ensue. This paper suggests and implements a technique for a combined three-stage ‹‹penetration (with and without vacuum pumping)+TDS›› experiment and the corresponding mathematical toolkit. The informative capacity of the experiments and the accuracy of the estimation of hydrogen permeability parameters (adsorption, dissolution, diffusion and desorption) of the membrane materials under study are thus enhanced.     

非线性系统参数的多种群并行遗传优化

非线性系统参数优化的多种群并行遗传算法,以群体遗传算法搜索整个解空间实现参数优化.通过群体中个体间的信息交换,淘汰劣质基因,并用优秀个体反映解空间信息,使系统稳健收敛.该方法首先选取编码方案、交叉和变异概率、适应度函数、策略及遗传算子以及优秀个体的迁移率,并通过饱和非线性环节、速率限制环节和三阶环节验证了非线性系统的参数优化.     

创新和实践——重塑建筑产品和实践

本文首先简述了数码技术对建筑设计广泛影响的历史文脉,勾画出建筑实践目前面对的处境,提出建筑师需要据此创造性地调整设计的理念、方法和工具,并重点阐述了当今建筑实践网络化的特点。     

壳体结构形态的量化重构——基于建筑参数化设计技术与结构力学的协同机制

复杂形态与结构体系之间所存在的数学逻辑与力学法则之间的偏差,构成了当今国际建筑参数化设计深化研究与面向现实实施的困境与挑战。因此,实现数字化复杂形态与结构力学逻辑的有机统一构成了该研究的初衷与最终目标。从结构工程学的角度出发,以双曲抛物面壳体为实验对象,提出了“结构原型——力学机制——力与形数字重构——验算与优化”的实验方法与创作思路,并通过圆形、三角形、菱形与编织状四种反映力学机制的肌理形式的量化试验与数据分析,论证了该技术路线的可行性与有效性,并最终形成一种从结构原型到多样性形态重塑的创新建筑设计模式。文中着力于如何利用与发掘潜在的结构力学机制,指出了复杂空间形态的创作如何结合结构力学的关键点,可为现时建筑参数化设计的现实运用与纵深研究提供实证参考与理论线索。     

实用主义代码70后中国建筑师之建筑数字观

文章指出,70后中国建筑师站在计算机带来的新技术变迁的时代前沿从电脑普及化到电脑计算化,首当其冲受到技术革命带来的设计方法和过程改变的洗礼,从而对数字设计具有敏锐触觉。70后受到的教育延续布扎体系,深悉建筑本质：几何形态、空间、质感,光线和建构。＂建房子＂的迫切需求让70后的数字时代的建筑观具有强烈实用主义的特征,这样的特征给在中国建筑实践和教育中崛起的70后带来了产生新建筑形态语言和思潮可能的机会。