Geodesign Approaches to City Resilience Planning: A Systematic Review

The increased frequency of extreme events facing society is placing mounting pressure on cities and regions that need more robust resilience planning against growing uncertainty. Data augmented participatory methods, such as geodesign, offer much promise in supporting strategic planning to make our cities and regions more resilient. In that context, this study aims to contribute to a deeper understanding of geodesign practices in resilience planning, through a systematic review of the selected 487 studies available from various bibliographic databases. The results indicate that a total of 75 studies were connected to resilience thinking, with a focus on climate change, floods, and sea level rise risks. A significant cluster of those resilience-related studies worked, especially, on improving sustainability. A detailed analysis of 59 relevant geodesign case studies revealed a strong underlying emphasis on disaster risk reduction and management activities. This study also noticed two prominent approaches among the analysed case studies to future city scenario planning: computational (41 studies), and collaborative (18 studies). It is recommended that an explicit integration of these two approaches into the geodesign approach can assist future city resilience planning endeavours. Thus, future research should further investigate the utility of integrating data-driven modelling and simulation within a collaborative scenario planning process, the usability of digital tools such as planning support systems within a collaborative geodesign framework, and the value of the plan’s performance evaluation during resilience decision-making. Another area for future work is increased community engagement in city resilience practices. The geodesign approach can provide a comprehensive framework for bringing communities, decision-makers, experts, and technologists together to help plan for more resilient city futures. Finally, while geodesign’s explicit role in empirical resilience implementations has been found to be low in this systematic review study, there are significant opportunities to support evidence-based and collaborative city resilience planning and decision-making activities.

FEM Simulation of the Riveting Process and Structural Analysis of Low-Carbon Steel Tubular Rivets Fracture

Riveted joints are a common way to connect elements and subassemblies in the automotive industry. In the assembly process, tubular rivets are loaded axially with ca. 3 kN forces, and these loads can cause cracks and delamination in the rivet material. Such effects at the quality control stage disqualify the product in further assembly process. The article presents an analysis of the fracture mechanism of E215 low-carbon steel tubular rivets used to join modules of driver and passenger safety systems (airbags) in vehicles. Finite element method (FEM) simulation and material testing were used to verify the stresses and analysis of the rivet fracture. Numerical tests determined the state of stress during rivet forming using the FEM-EA method based on the explicit integration of central differences. Light microscopy (LM), scanning electron microscopy (SEM) and chemical composition analysis (SEM-EDS) were performed to investigate the microstructure of the rivet material and to analyze the cracks. Results showed that the cause of rivet cracking is the accumulation and exceeding of critical tensile stresses in the rivet flange during the tube processing and the final riveting (forming) process. Moreover, it was discovered that rivet fracture is largely caused by structural defects (tertiary cementite Fe,Mn3CIII along the boundaries of prior austenite grains) in the material resulting from the incorrectly selected parameters of the final heat treatment of the prefabricate (tube) from which the rivet was produced. The FEM simulation of the riveting and structural characterization results correlated well, so the rivet forming process and fracture mechanism could be fully investigated.

Addressing the call: A review of food justice courses in Canada and the USA

To address inequality's root causes both within and beyond the food chain, food justice scholars have called for explicit integration of trauma/inequity, land, labour, exchange, and governance into post-secondary education food studies and related fields. This paper explores how instructors of food justice courses (identified by key-word internet search) in Canada and the United States are designing their courses. We collected course syllabi from fifteen institutions to determine key themes related to course content based on weekly topics and readings, resulting in the identification of 16 thematic content areas. We identified seven thematic areas related to course goals (n=49) and eight thematic areas related to learning outcomes (n=123). To clearly distinguish between themes represented in the syllabi, we embedded course goals and learning outcomes into the Understanding by Design instructional design framework, which demonstrates how course goals can be separated into the categories of transfer and meaning, and learning outcomes into declarative and procedural knowledge. We examine content areas in relation to food justice scholarship, focusing on what is present, underrepresented, and absent. In consideration of the Understanding by Design framework, we discuss the need for established goals within which to situate food justice courses, challenges of course scope, value of scaffolding goals and outcomes across programs, and future directions for aligning potential indicators of understanding and identifying effective learning activities. The intended outcome of the paper is to provide current and prospective instructors with greater clarity on how food justice is being taught in order to increase our collective effectiveness in developing student capacities in the field.

Efficient Numerical Treatment of Ambipolar and Hall Drift as Hyperbolic System

Partially ionized plasmas, such as the solar chromosphere, require a generalized Ohm’s law including the effects of ambipolar and Hall drift. While both describe transport processes that arise from the multifluid equations and are therefore of hyperbolic nature, they are often incorporated in models as a diffusive, i.e., parabolic process. While the formulation as such is easy to include in standard MHD models, the resulting diffusive time-step constraints do require often a computationally more expensive implicit treatment or super-time-stepping approaches. In this paper we discuss an implementation that retains the hyperbolic nature and allows for an explicit integration with small computational overhead. In the case of ambipolar drift, this formulation arises naturally by simply retaining a time derivative of the drift velocity that is typically omitted. This alone leads to time-step constraints that are comparable to the native MHD time-step constraint for a solar setup including the region from photosphere to lower solar corona. We discuss an accelerated treatment that can further reduce time-step constraints if necessary. In the case of Hall drift we propose a hyperbolic formulation that is numerically similar to that for the ambipolar drift and we show that the combination of both can be applied to simulations of the solar chromosphere at minimal computational expense.

Precomputation of Critical State Soil Plastic Models

In this paper, a simple precomputing procedure is proposed to improve the numerical performance of the technological application of critical state soil models. In these models, if associated plasticity is assumed, the normalization of the stress space allows both the yield surface and the plastic components of the elastoplastic matrix to be defined as a function of a single variable. This approach facilitates their parameterization and precomputation, preventing the repetition of calculations when the boundary value problems appear at the yield surface with the calculation of plastic strain. To illustrate the scope of the procedure, its application on a modified Cam Clay model is analysed, which shows that the method allows a significant reduction of about 50% (as compared with the conventional explicit integration algorithm) in the computational time without reducing the precision. Although it is intended for critical state models in soils, the approach can be applied to other materials and types of constitutive models provided that parameterization is possible. It is therefore a methodology of practical interest, especially when a large volume of calculations is required, for example when studying large-scale engineering systems, performing sensitivity analysis, or solving optimization problems.

Avoiding Dynamical Degradation in Computer Simulation of Chaotic Systems Using Semi-Explicit Integration: Rössler Oscillator Case

Dynamical degradation is a known problem in the computer simulation of chaotic systems. Data type limitations, sampling, and rounding errors give rise to the periodic behavior. In applications of chaotic systems in secure communication and cryptography systems, such effects can reduce data storage security and operation. In this study, we considered a possible solution to this problem by using semi-explicit integration. The key idea is to perturb the chaotic trajectory by switching between two integrators, which possess close but still different numerical solutions. Compared with the traditional approach based on the perturbation of the bifurcation parameter, this technique does not significantly change the nonlinear properties of the system. We verify the efficiency of the proposed perturbation method through several numerical experiments using the well-known Rössler oscillator.

Gas/Liquid Two-Phase Flow in Pipes: Slugs, Classical Flow-Map, and 1D Compositional Simulation

Summary In this paper, I present numerical results of gas/liquid flows in pipelines obtained from a new simulation code. One difference, with respect to other 1D fluid dynamic commercial simulation products, is the use of a compositional approach to the problem: This is rarely found in published articles about gas/liquid flow in the oil and gas industry. It is shown that the algorithm can calculate both pressure and material fast waves generated during the transportation of gas and liquid in pipes. The solution algorithm is based on the application of a two-fluid model to the mass, momentum, and energy conservation equations, which are solved using a mixed implicit-explicit integration schema. Closure equations for the calculation of interface stress are taken from literature articles. A dam-break simulation (i.e., a Riemann initial value problem) is presented as a severe test case for validation of the two-phase flow algorithm. Because the code is able to capture sharp and fast changes in the liquid holdup connected to the formation of pressure waves, it is applied to the simulation of slug flow without the use of steady-state “unit cell” models and slug tracking functions. In this context, the experimental results on pseudoslug formation in inclined pipes at high pressures, published by the Tulsa University Fluid Flow Project (TUFFP), are used to compare simulated results with experimental data. The last part is dedicated to the simulation of some cases taken from a classical flow-map of a fundamental article by Taitel and Dukler (1976). At constant liquid superficial velocity, the formation of liquid slugs and their subsequent termination with the increase of gas flow rate is simulated with details never previously presented.