Computational synthesis of substrates by crystal cleavage

The discovery of substrate materials has been dominated by trial and error, opening the opportunity for a systematic search. We generate bonding networks for materials from the Materials Project and systematically break up to three bonds in the networks for three-dimensional crystals. Successful cleavage reduces the bonding network to two periodic dimensions. We identify 4693 symmetrically unique cleavage surfaces across 2133 bulk crystals, 4626 of which have a maximum Miller index of one. We characterize the likelihood of cleavage by creating monolayers of these surfaces and calculating their thermodynamic stability using density functional theory to discover 3991 potential substrates. Following, we identify distinct trends in the work of cleavage and relate them to bonding in the three-dimensional precursor. We illustrate the potential impact of the substrate database by identifying several improved epitaxial substrates for the transparent conductor BaSnO3. The open-source databases of predicted and commercial substrates are available at MaterialsWeb.org.

The reestablishment of Mosul's city fabric: an approach to computational hybridization

PurposeThis paper aims out to analyze the confluence of spatial analysis and computational design strategies to support the reestablishment of Mosul's city housing fabric. According to a UN-Habitat report, Mosul suffered from catastrophic losses on an urban scale, resulting in a housing crisis that requires a large-scale response. However, the need for immediate shelters might lead to a rapid, uninformed reconstruction process, causing the loss of the architectural identity that the city accumulated over the years.Design/methodology/approachThe study utilizes a two-phase sequential research method. In Phase 1, the study applies space syntax techniques to transform the floor plans of the collected traditional and contemporary houses into “quantifiable data.” This phase aims to identify design criteria that capture the “spatial configuration” of both types of houses. In the subsequent phase, the study utilizes the identified design criteria to develop a genetic algorithm inspired by traditional and contemporary practice that facilitates an informed design process.FindingsThe outcome of the study indicates that informed computational synthesis can assist in generating multiplicities floor plan layouts that mimic the inner spatial configuration of existing traditional courtyard houses and contemporary noncourtyard houses. In addition, the developed genetic algorithm was able to generate hybridized design solutions that have been spatially validated.Originality/valueThe study concludes with observations linking informed computational synthesis to the postwar construction process as a remedial methodology to analyze and redesign Mosul's city fabric in an informed, affordable and accessible fashion.

Kinematic Design and Evaluation of a Six-Bar Knee-Ankle-Foot Orthosis

This paper presents a new two-step design procedure and preliminary kinematic evaluation of a novel, passive, six-bar knee-ankle-foot orthosis (KAFO). The kinematic design and preliminary kinematic gait analysis of the KAFO are based on motion capture data from a single healthy male subject. Preliminary kinematic evaluation shows that the designed passive KAFO is capable of supporting flexion and extension of the knee joint during stance and swing phases of walking. The two-step design procedure for the KAFO consists of (1) computational synthesis based on user's motion data and (2) performance optimization. In the computational synthesis step, first the lower leg (knee-ankle-foot) of the subject is approximated as a 2R kinematic chain and its target trajectories are specified from motion capture data. Six-bar linkages are synthesized to coordinate the angular movements of knee and ankle joints of the 2R chain at 11 accuracy points. The first step of the design procedure yields 332 six-bar KAFO design candidates. This is followed by a performance optimization step in which the KAFO design candidates are optimally modified to satisfy specified constraints on end-effector trajectory and shape. This two-step process yields an optimally designed passive six-bar KAFO that shows promising kinematic results at the knee joint of the user during walking. The preliminary prototype manufactured is cost effective, easy to operate, and suitably demonstrates the feasibility of the proposed concept.