Narrative approaches to design multi-screen augmented reality experiences

This paper explores how traditional narrative language used in film and theatre can be adapted to create interactivity and a greater sense of presence in the virtual heritage environment. It focuses on the fundamental principles of narrative required to create immersion and presence and investigates methods of embedding intangible social histories into these environments. These issues are explored in a case study of Greens Mill in the 1830’s, interweaving the story of the reform bill riots in Nottingham with the life of George Green, mathematician and proprietor of the Mill

Narrating the past: virtual environments and narrative

This paper explores how traditional narrative language used in film and theatre can be adapted to create interactivity and a greater sense of presence in the virtual heritage environment. It focuses on the fundamental principles of narrative required to create immersion and presence and investigates methods of embedding intangible social histories into these environments. These issues are explored in a case study of Greens Mill in the 1830’s, interweaving the story of the reform bill riots in Nottingham with the life of George Green, mathematician and proprietor of the Mill

Exact and semiclassical approach to a class of singular integral operators arising in fluid mechanics and quantum field theory

A class of singular integral operators, encompassing two physically relevant cases arising in perturbative QCD and in classical fluid dynamics, is presented and analyzed. It is shown that three special values of the parameters allow for an exact eigenfunction expansion; these can be associated to Riemannian symmetric spaces of rank one with positive, negative or vanishing curvature. For all other cases an accurate semiclassical approximation is derived, based on the identification of the operators with a peculiar Schroedinger-like operator.Comment: 12 pages, 1 figure, amslatex, bibtex (added missing label eq.11

First, do no harm: Evaluating resources for teaching social entrepreneurship

We reviewed two key repositories of social entrepreneurship pedagogical resources: Ashoka.org and CasePlace.org. Each provides a set of useful resources, comprising videos, syllabi, cases, readings and other resources that make it easy for instructors to design social entrepreneurship courses, modules, or programs. We caution against what we see as overenthusiasm for the topic, however, since social entrepreneurship involves tinkering with social structures, sometimes with disastrous unintended effects. We advise instructors to teach their students to think critically about social entrepreneurship initiatives, since they include the potential for harm as well as good. © Academy of Management Learning & Education

Selective Heat Sintering Versus Laser Sintering: Comparison of Deposition Rate, Process Energy Consumption and Cost Performance

The Selective Heat Sintering (SHS) process has become available as a low cost alternative to Laser Sintering (LS) for the additive deposition of polymer objects. While both processes belong to the powder bed fusion variant of Additive Manufacturing (AM) technology, their operating principles vary significantly: SHS employs a thermal print head to selectively fuse material powder, whereas the LS approach utilizes a laser beam coupled with a galvanometer. Based on a series of build experiments, this research compares these technology variants along three dimensions of process efficiency: deposition rate (measured in cm³/h), specific process energy consumption (MJ/kg) and specific cost ($/cm³). To ensure that both platforms are assessed under the condition of efficient technology utilization, an automatic build volume packing algorithm is employed to configure a subset of build experiments. Beyond reporting absolute and relative process performance, this paper additionally investigates how sensitive the compared processes are to a variation in the degree of capacity utilization and discusses the application of different levels of indirect cost in models of low cost AM.Mechanical Engineerin

Inserting Components into Geometries Constructed onto a Non-Standard Substrate for Electronics Packaging

Additive manufacturing (AM) has matured from its initial concept as a prototyping technique to an industrial manufacturing process. Consequently, AM processes must meet relevant standards for an increasing number of applications. Here, we investigate inserting components into geometries constructed onto a silicon nitride substrate, using stereolithography (SLA), for the purpose of electronics packaging. Compared to conventional processes, SLA avoids high temperatures and stresses while permitting much greater flexibility to arrange components in three dimensions. This facilitates an increased feature density and the construction of packages for use in complex spaces. A characteristic of interest to this application, is the SLA material-substrate interaction and the resulting quality of adhesion. The adhesion mechanism between SLA and silicon nitride is investigated and substantially enhanced by a pre-treatment process. A process for then inserting large and complex geometries and components into the SLA build process is identified and compliance of the product with relevant standards is reviewed.Mechanical Engineerin

High Viscosity Jetting of Conductive and Dielectric Pastes for Printed Electronics

Ink-jet printing of multiple materials in 3 dimensions is a promising alternative to traditional patterning methods due to its flexibility, scalability and accuracy. However, the printability of the inks is strongly restricted by material properties such as surface tension and viscosity. Dispensing high viscosity fluids on a drop-on-demand approach is a potential solution that can facilitate the incorporation of new materials to the jetting catalogue. Consequently, in this study 2 micro-dispensing valves are used in combination with a mechanical stage to deposit conductive and dielectric pastes with viscosities of 15.3 ± 0.2 and 0.638 ± 0.005 Pa·s (at 25°C and 10 s-1 shear rate) respectively. Crucial printing parameters such as pressure, temperature, pulse shape and drop spacing are studied in order to optimise the process. Additionally, post-printing characteristics such as contact angle of different materials and cured layer profiles are also measured and taken into account during the designing of the 3D patterns to minimise the negative effects of the thickness miss-match of different materials. Finally, the manufacturing capability of the set-up is demonstrated by the fabrication of a functional device using a combination of “pick-and-place” components and high viscosity jetting.Mechanical Engineerin

How Can Material Jetting Systems Be Upgraded for More Efficient Multi-Material Additive Manufacturing

Multi-material Additive Manufacturing (AM) platforms are able to build up components from multiple materials in a single layer-by-layer process. It is expected that this capability will enable the manufacturing of functional structures within products, such as conductive tracks or optical pathways, resulting in radically novel products with unprecedented degrees of functional density. An important variant of commercially available multi-material AM technology is material jetting, which is currently in commercial use for the manufacture of prototypes and design studies. This paper presents a detailed process model of build-time, energy consumption and production cost for the Stratasys Objet 260 Connex system, analyzing the contemporaneous deposition of two different types of photopolymers (Veroclear RGD810 and Tangoblack FLX973). By using this process model to anticipate the effects of various upgrades to the investigated system, such as a larger build volume and a higher deposition speed, this forward-looking paper explores pathways to enhancing the value proposition of such multi-material systems through incremental technology improvement.Mechanical Engineerin