Deformation processing of high-Tc superconducting oxides

Plastic deformation and texture development in polycrystalline YBa₂Cu₃O_{7? δ} has been studied to expedite the process development of high-critical-temperature (high-T_c) superconducting wires and tapes. It is anticipated that deformation texture will be a major processing consideration in terms of maximizing critical current density, assessing conductor-fabrication options in light of critical current density, and developing such mechanical properties as strength, toughness and thermal fatigue. The intrinsic texture development in YBa₂Cu₃O_{7? δ} deformation processing should be highly beneficial, insofar as the c axes of the crystals tend to become oriented along the compression axis. This means that conducting tapes and wires formed by rolling, extrusion and drawing can develop textures with the c axis in the transverse or radial direction, thus maximizing the flow of current along the length of the conductor.     

毛细管通道聚合纤维：液相分离新平台

以微米级内径的纤维作为色谱填料的研究已经活跃了很多年,但是由于重现性较差和填充过程难以控制等问题,使其商品化过程大大延缓.近来发展起来的一种新型聚合纤维材料可以克服已有的许多缺陷,有望作为新一代的色谱固定相.     

Choosing a wrong mobile communication price plan: An empirical analysis of predictors of the degree of tariff misfit among flat rate subscribers in Germany

Worldwide, more and more users of mobile communication services (MCS) are in tariffs which decouple the level of customer usage of one or several MCS (voice calls, Internet access, SMS) from the fixed monthly charge of mobile network operators (MNOs). However, consumers may inappropriately subscribe to such a flat rate because other usage-dependent price schemes are available which more closely match with their MCS use patterns. Surprisingly, little research has examined how the degree of consumer tariff misfit is correlated with socio-demographic, contract-, MCS-usage- and device-related subscriber characteristics. The present paper analyzes such associations. We develop two volume-based measures of the degree of tariff misfit in a sample of 1,274 subscribers of an MNO in Germany who had switched into a “grand flat rate” which includes unlimited national call minutes, mobile Internet traffic as well as national SMS. We find that the degree of tariff misfit is significantly higher among subscribers who are older, live in West Germany, have a longer MNO tenure, have larger monthly usage volume variations of voice calls, mobile Internet and SMS and are equipped with a device which is not an Apple iPhone. Implications of the results are discussed for MNO practitioners and for future scholarly work.     

Inhabitant actions and summer overheating risk in London dwellings

ABSTRACT

An indoor overheating assessment study of 101 London dwellings during summer 2009 is presented. The study included building surveys, indoor dry bulb temperature monitoring and a questionnaire survey on occupant behaviour, including the operation of passive and active ventilation, cooling and shading systems. A theoretical London housing stock comprising 3456 combinations of building geometry, orientations, urban patterns, fabric retrofit and external weather was simulated using the EnergyPlus thermal modelling software. A statistical meta-model of EnergyPlus was then built by regressing the independent variables (simulation input) against the dependent variables (overheating risk). The monitoring and questionnaire data were analysed to explore the relationship between self-reported behaviour and overheating, and to test the meta-model. The monitoring data indicated that London homes and, in particular, bedrooms are already at risk of overheating during hot spells under the current climate. Around 70% of respondents tended to open only one or no windows at night mainly due to security reasons. An improvement in the coefficient of determination (R²) values between measured temperature and meta-model predictions was obtained only for those dwellings where occupants reported actions that were in line with the modelling assumptions, thus highlighting the importance of occupant behaviour for overheating.     

Memorials to Modernity? Public art in the 'city of the future'

This paper examines the role of public art in urban redevelopment, focusing on the reconstruction of Coventry (UK) in the post-war years. Overseen by the city's Chief Architect, Donald Gibson, this redevelopment has often been described as resulting in a placeless and artless urban landscape indistinguishable from other redeveloped city centres in post-war Britain. To the contrary, here it is suggested that public art was an important feature of Coventry's new urban landscape, with the attempt to create a new civic identity manifest in a series of highly symbolic and distinctive public artworks. Analysing both the official symbolism of these artworks and their reception in the public sphere, it is concluded that, although just one aspect of the urban landscape, the production and consumption of public art encapsulated the tensions that existed between different visions of the city.     

Exploiting perceptual limitations and illusions to support walking through virtual environments in confined physical spaces

Head-mounted displays (HMDs) allow users to immerse in a virtual environment (VE) in which the user’s viewpoint can be changed according to the tracked movements in real space. Because the size of the virtual world often differs from the size of the tracked lab space, a straightforward implementation of omni-directional and unlimited walking is not generally possible. In this article we review and discuss a set of techniques that use known perceptual limitations and illusions to support seemingly natural walking through a large virtual environment in a confined lab space. The concept behind these techniques is called redirected walking. With redirected walking, users are guided unnoticeably on a physical path that differs from the path the user perceives in the virtual world by manipulating the transformations from real to virtual movements. For example, virtually rotating the view in the HMD to one side with every step causes the user to unknowingly compensate by walking a circular arc in the opposite direction, while having the illusion of walking on a straight trajectory. We describe a number of perceptual illusions that exploit perceptual limitations of motion detectors to manipulate the user’s perception of the speed and direction of his motion. We describe how gains of locomotor speed, rotation, and curvature can gradually alter the physical trajectory without the users observing any discrepancy, and discuss studies that investigated perceptual thresholds for these manipulations. We discuss the potential of self-motion illusions to shift or widen the applicable ranges for gain manipulations and to compensate for over- or underestimations of speed or travel distance in VEs. Finally, we identify a number of key issues for future research on this topic.     

Head tracked retroreflecting 3D display

In this paper, we describe a single‐user glasses‐free (autostereoscopic) 3D display where images from a pair of picoprojectors are projected on to a retroreflecting screen. Real images of the projector lenses formed at the viewer's eyes produce exit pupils that follow the eye positions by the projectors moving laterally under the control of a head tracker. This provides the viewer with a comfortable degree of head movement. The retroreflecting screen, display hardware, infrared head tracker, and means of stabilizing the image position on the screen are explained. The performance of the display in terms of crosstalk, resolution, image distortion, and other parameters is described. Finally, applications of this display type are suggested.     

Making Things Visible: Opportunities and Tensions in Visual Approaches for Design Research and Practice

Visual approaches for conducting research during the design process often give voice to people and ideas that might otherwise remain obscured. Recent and increasing interest in visual research techniques has coincided with technological advances such as camera phones and visually oriented mobile applications. As a result of this close association between digital technologies and image-based research techniques, there are multiple opportunities and challenges within human–computer interaction (HCI) design practice to employ these strategies to improve user experiences. This article provides an overview of current visual approaches to research highlighting the role technology has played in facilitating and inspiring these techniques. A series of case studies are presented that provide a basis for understanding a breadth of visual approaches in HCI design practices as well as serve as a point of entry to a critical and reflective discussion about the use of these approaches in different circumstances. Based on these reflections, three value statements are offered as a means to encourage the use of these visual approaches more broadly and critically in HCI design studies.     

A hearing-inspired approach for distant-microphone speech recognition in the presence of multiple sources

This paper addresses the problem of speech recognition in reverberant multisource noise conditions using distant binaural microphones. Our scheme employs a two-stage fragment decoding approach inspired by Bregman's account of auditory scene analysis, in which innate primitive grouping ‘rules’ are balanced by the role of learnt schema-driven processes. First, the acoustic mixture is split into local time-frequency fragments of individual sound sources using signal-level primitive grouping cues. Second, statistical models are employed to select fragments belonging to the sound source of interest, and the hypothesis-driven stage simultaneously searches for the most probable speech/background segmentation and the corresponding acoustic model state sequence. The paper reports recent advances in combining adaptive noise floor modelling and binaural localisation cues within this framework. By integrating signal-level grouping cues with acoustic models of the target sound source in a probabilistic framework, the system is able to simultaneously separate and recognise the sound of interest from the mixture, and derive significant recognition performance benefits from different grouping cue estimates despite their inherent unreliability in noisy conditions. Finally, the paper will show that missing data imputation can be applied via fragment decoding to allow reconstruction of a clean spectrogram that can be further processed and used as input to conventional ASR systems. The best performing system achieves an average keyword recognition accuracy of 85.83% on the PASCAL CHiME Challenge task.     

A microfluidic vibrating wire viscometer for operation at high pressure and high temperature

This article discusses a microfluidic vibrating wire viscometer with an internal volume of a few microliters. Accuracy of order ±10% for viscosities ranging from 0.1 to 100 cP is demonstrated for temperatures (10 °C-175 °C) and pressures (10-24,000 psi) suitable for oilfield use by prior calibration in air and toluene. Comparison between multiple data sets indicates that a large fraction of the discrepancy between literature values is systematic, indicating that future refinements may be possible with better interpretation. Confinement effects are evaluated and are not found to play a significant role, which is surprising since the ratio (6.6) of the fluid channel width to the wire diameter is very low.