Pop-up Home: Evidencing an urban nomad’s distributed domestic intimacy beyond a sedentary home

“A home is not a house” can be read as a design hypothesis for an alternative urban domesticity and an attempt to explore a more distributed mode of existence than what a fixed house might have presumably confined for its users. In this design hypothesis, the sedentary narrative for the design of a fixed house was questioned, mostly on its physical forms and as well, on its social implications. As a design research, Pop-up Home further explores this design hypothesis in a refreshed context of a distributed home and on a focused subject of domestic intimacy. For Pop-up Home, domestic intimacy can be defined as a spatial “sense of home” which can be found extending beyond a sedentary home. Pop-up Home takes on a combination of an auto-ethnographic and a participatory action research. Through the perspective of an auto-ethnographic urban nomad, the design research collects a set of “lived-experience” ranging from being a compact home renter, to a “rug sojourner”, then to a “rickshaw-bed rider”, and to a “digital nomad” with a lifestyle of “living as service” via distributed accommodation platforms such as Airbnb and Couchsurfing, etc. Through this perspective of the urban nomad, the MPhil thesis explores spatial evidence for alternative forms of urban domesticity which are not based upon a fixed house, but rather which take a more distributed form. Through the same perspective, the thesis also explores an alternative design narrative of urban domesticity in which a new social form of domestic life in a more distributed mode is emerging. The collected examples of urban nomads and their distributed domestic intimacy have been captured through the auto-ethnographic work and experiential encounters in Hong Kong, Pune India, and London. Documenting and curating the above set of examples, and based on the theoretical framework of “spatial agency”, the design research constructs both an empathetic and an intellectual framework for understanding the evidenced changes in urban domesticity, in relation to the increasingly precarious conditions of life in modern economies. The MPhil thesis, as a phase of the design research overall, aims to focus on the conflicts between the institution of the sedentary home and the nomadic nature of a “creative user”; and to evoke a positive ideology where a fixed house could be planned, transformed, maintained, and/or altered creatively by these users. This framework for a distributed home might lead to a specific method of “participatory design” to think, practice, and finance future urban domesticity in a “small, local, open and connected” design scenario of a world city, and contribute to a more genuine human-centred design method and design thinking for future urban domesticity

Cubic B-spline curve approximation by curve unclamping

International audienceA new approach for cubic B-spline curve approximation is presented. The method produces an approximation cubic B-spline curve tangent to a given curve at a set of selected positions, called tangent points, in a piecewise manner starting from a seed segment. A heuristic method is provided to select the tangent points. The first segment of the approximation cubic B-spline curve can be obtained using an inner point interpolation method, least-squares method or geometric Hermite method as a seed segment. The approximation curve is further extended to other tangent points one by one by curve unclamping. New tangent points can also be added, if necessary, by using the concept of the minimum shape deformation angle of an inner point for better approximation. Numerical examples show that the new method is effective in approximating a given curve and is efficient in computation

PDE-Based and Solution-Dependent Parameterization for Isogeometric Analysis

This paper presents some results for PDE-based and solution-dependent parameterization of computational domains for isogeometric analysis (IGA) using non-uniform rational B-splines (NURBS). The final parameterization is produced based on the solution of a partial differential equation (PDE) that is solved using isogeometric collocation method (IGA-C) with Dirichlet boundary condition being the input boundary of the final desired computational domain for IGA, namely the IGA-C-PDE method for domain parameterization. The theory of PDE guarantees that the mapping between physical and transformed region will be one-to-one. In addition, we also apply intuitive position and ratio constraints while solving the PDE to achieve solution-dependent parameterization. While one may use any general PDE with any constraint, the PDEs and additional constraints selected in our case are such that the resulting solution can be efficiently solved through a system of linear equations with or without additional linear constraints. This approach is different from typical existing parameterization methods in IGA that are often solved through an expensive nonlinear optimization processes. The results show that the proposed method can efficiently produce satisfactory analysis-suitable parameterization

Bas-relief modeling from normal images with intuitive styles

Traditional 3D model-based bas-relief modeling methods are often limited to model-dependent and monotonic relief styles. This paper presents a novel method for digital bas-relief modeling with intuitive style control. Given a composite normal image, the problem discussed in this paper involves generating a discontinuity-free depth field with high compression of depth data while preserving or even enhancing fine details. In our framework, several layers of normal images are composed into a single normal image. The original normal image on each layer is usually generated from 3D models or through other techniques as described in this paper. The bas-relief style is controlled by choosing a parameter and setting a targeted height for them. Bas-relief modeling and stylization are achieved simultaneously by solving a sparse linear system. Different from previous work, our method can be used to freely design basreliefs in normal image space instead of in object space, which makes it possible to use any popular image editing tools for bas-relief modeling. Experiments with a wide range of 3D models and scenes show that our method can effectively generate digital bas-reliefs

Observation of Higher Order Nodal Line Semimetal in Phononic Crystals

Higher-order topological insulators and semimetals, which generalize the conventional bulk-boundary correspondence, have attracted extensive research interest. Among them, higher-order Weyl semimetals feature two-fold linear crossing points in three-dimensional (3D) momentum space, 2D Fermi-arc surface states, and 1D hinge states. Higher-order nodal-point semimetals possessing Weyl points or Dirac points have been implemented. However, higher-order nodal-line or nodal-surface semimetals remain to be further explored in experiments in spite of many previous theoretical efforts. In this work, we realize a second-order nodal-line semimetal in 3D phononic crystals. The bulk nodal lines, 2D drumhead surface states guaranteed by Zak phases, and 1D flat hinge states attributed to kz-dependent quadrupole moments, are observed in simulations and experiments. Our findings of nondispersive surface and hinge states may promote applications in acoustic sensing and energy harvesting.Comment: accepted for publication in PR

Subdivision surface for CAD-an overview

Subdivision surfaces refer to a class of modelling schemes that define an object through recursive subdivision starting from an initial control mesh. Similar to B-splines, the final surface is defined by the vertices of the initial control mesh. These surfaces were initially conceived as an extension of splines in modelling objects with a control mesh of arbitrary topology. They exhibit a number of advantages over traditional splines. Today one can find a variety of subdivision schemes for geometric design and graphics applications. This paper provides an overview of subdivision surfaces with a particular emphasis on schemes generalizing splines. Some common issues on subdivision surface modelling are addressed. Several key topics, such as scheme construction, property analysis, parametric evaluation and subdivision surface fitting, are discussed. Some other important topics are also summarized for potential future research and development. Several examples are provided to highlight the modelling capability of subdivision surfaces for CAD applications

2 An Approach for Solid Modelling in a Virtual Reality Environment

With today’s Virtual Reality (VR) systems, it is difficult to directly and precisely create and modify objects in a VR environment. This chapter presents an approach for solid modelling in a VR environment. Solid modelling in the VR environment is performed precisely in an intuitive manner through constraint-based manipulations. A hierarchically structured and constraint-based data model is developed to support solid modelling in the VR environment. The data model integrates a high-level constraint- based model for precise object definition, a midlevel CSG/Brep (Constructive Solid Geometry/Boundary representation) hybrid solid model for hierarchical geometry abstractions and object creation, and a lowlevel polygon model for real-time visualization and interaction in the VR environment. Constraints are embedded in the solid model and are organized at different levels to reflect the modelling process from features to parts. Constraintbased manipulations are accompanied with automatic constraint recognition and precise constraint satisfaction to establish the hierarchically structured constraintbased data model and are realized by allowable motions for precise 3D interactions in the VR environment. The allowable motions are represented as a mathematical matrix for conveniently deriving allowable motions from constraints. A procedure-based degree-of-freedom combination approach for 3D constraint solving is presented for deriving the allowable motions. A rule-based constraint recognition engine is developed for both constraint-based manipulations and implicitly incorporating constraints into the VR environment. A prototype system has been implemented for precise solid modelling in an intuitive manner through constraint-based manipulations