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.     

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.     

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.     

From regional sensitivity to intra-sensitivity for parametric analysis of free-form shapes: Application to ship design

Robust Parametric Sensitivity Analysis (PSA) is a prerequisite for efficient shape optimisation via parametric modelling. A major challenge PSA has to handle is related to the fact that a parameter can be sensitive in certain local areas of the design space but become insensitive in others. Therefore, setting an applicable space for this analysis becomes a difficult task. In this paper, we introduce the concept of intra-sensitivity to identify parameters whose perturbation has a major impact on the sensitivity index of the remaining parameters. For this purpose, we firstly appeal to Active Subspace Method (ASM) and develop an ASM-based regional sensitivity analysis, which investigates parametric sensitivity in local regions of the design space and aids conducing to parameters’ intra-sensitivity. This regional analysis is applied in conjunction with a Dynamic Propagation Sampling approach, for tackling the computational complexity arising when high-dimensional problems are concerned. Once sensitive and intra-sensitive parameters are identified, then free-form features, correlated to these parameters, are evaluated using a feature saliency map built with the aid of Hausdorff distance. The so resulting methodology has been validated in the area of computer-aided ship design using two parametric modellers: the first one is a Procedural Deformation (PD) modeller which is based on T-splines and involves 24 parameters while the second one is based on Free-Form Deformation (FFD) and involves 104 parameters. The corresponding design spaces have been generated using a parent hull close to the KCS container ship and are analysed against hull’s volume of displacement and total resistance. Finally, the convergence performance of the various components of this approach is compared with state-of-the-art techniques.     

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.     

Parametric Solutions to the Generalized Discrete Yakubovich‐Transpose Matrix Equation

This paper is concerned with the complete parametric solutions to the generalized discrete Yakubovich‐transpose matrix equation X − AX^TB = CY. which is related with several types of matrix equations in control theory. One of the parametric solutions has a neat and elegant form in terms of the Krylov matrix, a block Hankel matrix and an observability matrix. In addition, the special case of the generalized discrete Yakubovich‐transpose matrix equation, which is called the Karm‐Yakubovich‐transpose matrix equation, is considered. The explicit solutions to the Karm‐Yakubovich‐transpose matrix equation are also presented by the so‐called generalized Leverrier algorithm. At the end of the paper, two examples are given to show the efficiency of the proposed algorithm.     

6-DOF主动波浪补偿液压平台的结构优化分析

开展6-DOF船用主动波浪补偿液压平台结构优化设计,旨在提升波浪补偿液压平台承载和空间补偿能力,减小补偿平台体积和质量。依据海浪运行形态给定六自由度船用波浪补偿液压平台所需的补偿参数指标,利用虚拟样机技术,在ADAMS软件仿真环境中建立该平台的参数化模型;以其最大负载为优化目标,对该参数化模型的结构尺寸进行优化,得到该平台结构尺寸的优化结果。结果表明：优化后,六自由度船用波浪补偿液压平台的负载能力较最初增加了约15%,支腿液压缸的行程减小了约13%,平台负载能力提升且结构更加紧凑合理。为检验此次对平台结构尺寸优化的有效性,利用SolidWorks软件建模,并导入ADAMS软件中仿真,检验了模型的补偿能力。     

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。