The importance of axial misalignment on the long term strength of polyethylene pipe butt fusion joints

The importance of axial misalignment at polyethylene pipe butt fusion joints has been assessed by undertaking elevated temperature lifetime tests. Both medium and high density polyethylene pipes were fusion joined to give aligned and controlled misaligned butt joints. These were tested under either a constant or fluctuating internal pressure loading using conditions that induced failure by slow, stable crck growth. It was observed that the lifetime of a butt joined system depends upon both the internal pressure or pressure range applied and the level of misalignment at the butt fusion joint. Increasing either the internal pressure (range) or the misalignment reduced system performance. These two variables of misalignment and internal pressure (range) may be incorporated into a single parameter, the amplified axial stress (or stress range) at the butt joint. This amplified or butt joint axial stress (or stress range) may be derived by considering the additional bending stresses introduced at the butt joint by virtue of misalignment combined with the axial stress loading.     

Using a conductive sphere as a probe to characterize the sensitivity of soft piezoresistive films

Flexible piezoresistive films, such as, carbon black/polydimethylsiloxane (C-PDMS) composites, are often used as skin analogs and integrated into complex array sensors for tactile sensing. The uniformity of the sensor characteristics heavily depends on the homogeneity of the composite. Therefore, the ability to locally characterize a film that will be integrated into a complex force sensor could be critical. Here, a method to characterize the local sensitivity of flexible piezoresistive films is presented. Using a conductive sphere, which was chosen over a flat probe to eliminate misalignment issues, the surface of a thin film composite is indented to characterize the change in resistivity in terms of average strain. Experiments were performed with 15 and 18 wt% carbon black C-PDMS films of varying thickness. The contact radius of the probe with the piezoresistive film was estimated using the Johnson-Roberts-Kendall contact theory. Theoretical contact area estimates were found to agree with contact radius measurements carried out using optically transparent PDMS films observed through an optical microscope. Results show that C-PDMS with 15 wt% carbon black exhibit a higher rate if change of resistivity and gauge factor than films of same thickness with 18 wt% carbon black. On the other hand, thicker films exhibit higher gauge factors for the two tested carbon black contents. Tests carried out at multiple locations yielded consistent sensitivity values, making these types of composites suitable for array type force sensors.     

Experiencing Nature: Embodying Animals in Immersive Virtual Environments Increases Inclusion of Nature in Self and Involvement With Nature

Immersive virtual environments (IVEs) produce simulations that mimic unmediated sensory experiences. 3 experiments (N = 228) tested how different modalities increase environmental involvement by allowing users to inhabit the body of animals in IVEs or watch the experience on video. Embodying sensory‐rich experiences of animals in IVEs led to greater feeling of embodiment, perception of being present in the virtual world, and interconnection between the self and nature compared to video. Heightened interconnection with nature elicited greater perceptions of imminence of the environmental risk and involvement with nature, which persisted for 1 week. Although the effect sizes were small to moderate, findings suggest that embodied experiences in IVEs may be an effective tool to promote involvement with environmental issues.     

Towards a smooth design process for static communicative node‐link diagrams

Node‐link infographics are visually very rich and can communicate messages effectively, but can be very difficult to create, often involving a painstaking and artisanal process. In this paper we present an investigation of node‐link visualizations for communication and how to better support their creation. We begin by breaking down these images into their basic elements and analyzing how they are created. We then present a set of techniques aimed at improving the creation workflow by bringing more flexibility and power to users, letting them manipulate all aspects of a node‐link diagram (layout, visual attributes, etc.) while taking into account the context in which it will appear. These techniques were implemented in a proof‐of‐concept prototype called GraphCoiffure, which was designed as an intermediary step between graph drawing/editing software and image authoring applications. We describe how GraphCoiffure improves the workflow and illustrate its benefits through practical examples.     

Dynamic analysis of Java program concepts for visualization and profiling

Concept assignment identifies units of source code that are functionally related, even if this is not apparent from a syntactic point of view. Until now, the results of concept assignment have only been used for static analysis, mostly of program source code. This paper investigates the possibility of using concept information within a framework for dynamic analysis of programs. The paper presents two case studies involving a small Java program used in a previous research exercise, and a large Java virtual machine (the popular Jikes RVM system). These studies investigate two applications of dynamic concept information: visualization and profiling. The paper demonstrates two different styles of concept visualization, which show the proportion of overall time spent in each concept and the sequence of concept execution, respectively. The profiling study concerns the interaction between runtime compilation and garbage collection in Jikes RVM. For some benchmark cases, we are able to obtain a significant reduction in garbage collection time. We discuss how this phenomenon might be harnessed to optimize the scheduling of garbage collection in Jikes RVM.     

A Level-Set Method for Computing the Eigenvalues of Elliptic Operators Defined on Compact Hypersurfaces

We demonstrate, through separation of variables and estimates from the semi-classical analysis of the Schrödinger operator, that the eigenvalues of an elliptic operator defined on a compact hypersurface in ? ⁿ can be found by solving an elliptic eigenvalue problem in a bounded domain Ω?? ⁿ . The latter problem is solved using standard finite element methods on the Cartesian grid. We also discuss the application of these ideas to solving evolution equations on surfaces, including a new proof of a result due to Greer (J. Sci. Comput. 29(3):321–351, 2006).     

Dynamic Shape and Appearance Modeling via Moving and Deforming Layers

We propose a model of the shape, motion and appearance of a scene, seen through a sequence of images, that captures occlusions, scene deformations, unconstrained viewpoint variations and changes in its radiance. This model is based on a collection of overlapping layers that can move and deform, each supporting an intensity function that can change over time. We discuss the generality and limitations of this model in relation to existing ones such as traditional optical flow or motion segmentation, layers, deformable templates and deformotion. We then illustrate how this model can be used for inference of shape, motion, deformation and appearance of the scene from a collection of images. The layering structure allows for automatic inpainting of partially occluded regions. We illustrate the model on synthetic and real sequences where existing schemes fail, and show how suitable choices of constants in the model yield existing schemes, from optical flow to motion segmentation and inpainting.     

An artist life cycle model for digital media content: Strategies for the Light Web and the Dark Web

This paper surveys and categorizes emerging digital media business models. We apply the customer activity cycle of Vandermerwe (2000) to the consumption of digital media, taking three phases into account: pre-consumption, consumption and post-consumption. Our analysis of the business models focuses on their social costs and benefits. We derive the parameters as follows: convenience of use, exposure, ease of compliance and administration. We distinguish two polar environments for digital media: the Dark Web with content created by the masses, and the Light Web with content created by big media. We develop an artist life cycle model in which different business models appear to be optimal at different stages of an artist’s career. Voluntary payment-based models seem to be ideal for newcomers in the Dark Web, while digital rights management-based and complementary product and service-based models are the likely choice of established artists in the Light Web. Established artists might change their approach again, using voluntary payment-based or complementary product and service-based models when they retire.     

Engineering of protein epitopes: a single deletion in a snake toxin generates full binding capacity to a previously unrecognized antibody

Structural features associated with the ability of a monoclonalantibody (mAb) to discriminate between protein variants areidentified and engineered. The variants are the curaremimetictoxin from Naja nigricollis and erabutoxin a or b from Laticaudasemifasciata which differ from each other by 16 substitutionsand one insertion. The neutralizing mAb M1 recognizes with highaffinity a topographical epitope on the surface of toxin , butfails to recognize the erabutoxins although they possess mostof the residues forming the presumed epitope. Examinations ofthe toxin and erabutoxin 3-D structures and molecular dynamicssimulations reveal several differences between the variants.In particular, the region involving the ß-turn 17–24is organized differently. Analysis of the differences foundin this region suggests that the insertion (or deletion) atposition 18 of the variant amino add sequences is particularlyimportant in determining the differential cross-reactivity.To test this proposal, residue 18 was deleted in one erabutoxinusing sitedirected mutagenesis, and the biological propertiesof the resulting mutant were examined. We found that full antigenicitywas restored in the previously unrecognized variant. The implicationsof this finding are discussed.