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Highly ordered BN ⊥ –BN ⊥ stacking structure for improved thermally conductive polymer composites
Get PDFThe substantial heat generation in modern electronic devices is one of the major issues requiring efficient thermal management. This work demonstrates a novel concept for the design of thermally conducting networks inside a polymer matrix for the development of highly thermally conductive composites. Highly ordered hexagonal boron nitride (hBN) structures are obtained utilizing a freeze-casting method. These structures are then thermally sintered to get a continuous network of BN⊥–BN⊥ of high thermal conductivity in which a polymer matrix can be impregnated, enabling a directional and thermally conducting composite. The highest achieved thermal conductivity (K) is 4.38 W m−1 K−1 with a BN loading of 32 vol%. The effect of sintering temperatures on the K of the composite is investigated to optimize connectivity and thermal pathways while maintaining an open structure (porosity ≈ 2.7%). The composites also maintain good electrical insulation (volume resistivity ≈ 1014 Ω cm). This new approach of thermally sintering BN⊥–BN⊥ aligned structures opens up a new avenue for the design and preparation of filler alignment in polymer-based composites for improving the thermal conductivity while maintaining high electrical resistance, which is a topic of interest in electronic packaging and power electronics applications
Contesting control: journeys through surrender, self-awareness and looseness of control in embodied interaction
Get PDFSensor fusion of motion-based sign language interpretation with deep learning
Get PDFSign language was designed to allow hearing-impaired people to interact with others. Nonetheless, knowledge of sign language is uncommon in society, which leads to a communication barrier with the hearing-impaired community. Many studies of sign language recognition utilizing computer vision (CV) have been conducted worldwide to reduce such barriers. However, this approach is restricted by the visual angle and highly affected by environmental factors. In addition, CV usually involves the use of machine learning, which requires collaboration of a team of experts and utilization of high-cost hardware utilities; this increases the application cost in real-world situations. Thus, this study aims to design and implement a smart wearable American Sign Language (ASL) interpretation system using deep learning, which applies sensor fusion that “fuses” six inertial measurement units (IMUs). The IMUs are attached to all fingertips and the back of the hand to recognize sign language gestures; thus, the proposed method is not restricted by the field of view. The study reveals that this model achieves an average recognition rate of 99.81% for dynamic ASL gestures. Moreover, the proposed ASL recognition system can be further integrated with ICT and IoT technology to provide a feasible solution to assist hearing-impaired people in communicating with others and improve their quality of life
Driver take-over reaction in autonomous vehicles with rotatable seats
Get PDFA new concept in the interior design of autonomous vehicles is rotatable or swivelling seats that allow people sitting in the front row to rotate their seats and face backwards. In the current study, we used a take-over request task conducted in a fixed-based driving simulator to compare two conditions, driver front-facing and rear-facing. Thirty-six adult drivers participated in the experiment using a within-subject design with take-over time budget varied. Take-over reaction time, remaining action time, crash, situation awareness and trust in automation were measured. Repeated measures ANOVA and Generalized Linear Mixed Model were conducted to analyze the results. The results showed that the rear-facing configuration led to longer take-over reaction time (on average 1.56 s longer than front-facing, p < 0.001), but it caused drivers to intervene faster after they turned back their seat in comparison to the traditional front-facing configuration. Situation awareness in both front-facing and rear-facing autonomous driving conditions were significantly lower (p < 0.001) than the manual driving condition, but there was no significant difference between the two autonomous driving conditions (p = 1.000). There was no significant difference of automation trust between front-facing and rear-facing conditions (p = 0.166). The current study showed that in a fixed-based simulator representing a conditionally autonomous car, when using the rear-facing driver seat configuration (where participants rotated the seat by themselves), participants had longer take-over reaction time overall due to physical turning, but they intervened faster after they turned back their seat for take-over response in comparison to the traditional front-facing seat configuration. This behavioral change might be at the cost of reduced take-over response quality. Crash rate was not significantly different in the current laboratory study (overall the average rate of crash was 11%). A limitation of the current study is that the driving simulator does not support other measures of take-over request (TOR) quality such as minimal time to collision and maximum magnitude of acceleration. Based on the current study, future studies are needed to further examine the effect of rotatable seat configurations with more detailed analysis of both TOR speed and quality measures as well as in real world driving conditions for better understanding of their safety implications
Numerical modelling of intra-wave sediment transport on sandy beaches using a non-hydrostatic, wave-resolving model
Get PDFThe mutual feedback between the swash zone and the surf zone is known to affect large-scale morphodynamic processes such as breaker bar migration on sandy beaches. To fully resolve this feedback in a process-based manner, the morphodynamics in the swash zone and due to swash-swash interactions must be explicitly solved, e.g., by means of a wave-resolving numerical model. Currently, few existing models are able to fully resolve the complex morphodynamics in the swash zone, and none is practically applicable for engineering purposes. This work aims at improving the numerical modelling of the intra-wave sediment transport on sandy beaches in an open-source wave-resolving hydro-morphodynamic framework (e.g., non-hydrostatic XBeach). A transport equation for the intra-wave suspended sediment concentration, including an erosion and a deposition rate, is newly implemented in the model. Two laboratory experiments involving isolated waves and wave trains are simulated to analyse the performance of the model. Numerical results show overall better performance in simulating single waves rather than wave trains. For the latter, the modelling of the morphodynamic response improves in the swash zone compared with the existing sediment transport modelling approach within non-hydrostatic XBeach, while the need of including additional physical processes to better capture sediment transport and bed evolution in the surf zone is highlighted in the paper
Multilingual education in minority-dominated regions in Xinjiang, People’s Republic of China
Get PDFRecent developments in multilingualism and multilingual education in minority-dominated regions in China highlight the importance of policy studies to support the national goals of achieving multilingualism (Feng and Adamson, 2015), especially in remote western regions such as Xinjiang Uygur Autonomous Region (XUAR) that pose geographical, socio-political, and educational challenges. This study investigates the effectiveness of language policies and the implementation of multilingual education for minority dominated regions in XUAR, and of the extent to which those policies support multilingual education. The data mainly comprise policy documents issued at the national, regional and institutional level, supplemented by interviews with policy makers at regional and local levels. The study finds that, while the policies at both national and regional levels regarding language education in China are generally supportive of multilingualism, in reality, some of the implemented practices at local school levels in XUAR are not totally consistent with the policy goals, while weak local capacity also hinders the implementation of multilingual education
What are the development priorities for management of type 2 diabetes by general practitioners in Ningbo, China: a qualitative study of patients’ and practitioners’ perspectives
Get PDFObjectives To explore patients’ and general practitioners’ (GPs’) perspectives on primary care management of patients with type 2 diabetes mellitus (T2DM) in Ningbo, China. We aimed to understand the current benefits and challenges and to identify development priorities.
Design Exploratory qualitative descriptive study using face-to-face interviews and analysed by thematic, inductive analysis.
Setting 11 primary care facilities spread across the city of Ningbo, China.
Participants 23 patients with T2DM and 20 GPs involved in caring for patients with T2DM.
Results GPs were considered the first point of contact and providers of information. However, the care varied, and many GPs lacked confidence and felt overworked. The medication was a particularly weak area. The diagnostic screening commenced late, leading to crisis presentations. Patients were variably informed about their condition, contributing to poor adherence.
Conclusions Future developments of primary care for T2DM in Ningbo should centre around improving GP confidence and workload and patient education and adherence
Online social media — a vehicle for city branding in China: the case of Sponge City Program (SCP)
Get PDFThe shift of academic attention from city marketing to city branding heralds a new era of representation and signification of cities as brands. Conscious practices of nationwide program implementation could be used not only for improving urban resilience but for city brands promotion. In China, to cope with the frequent occurrence of urban water issues, a nationwide initiative called Sponge City Program (SCP) has been launched since 2013. Given the significant impact of online social media on brand image, various levels of the Chinese Governments have begun to use online social media for city program promotion. In particular, brand community formed by stakeholders on online social media can significantly influence the brand image by co-creating contents. In this paper, we first analyze the current application of online social media for city marketing in China based on the SCP implementation. Next, we propose a framework/typology to inform how Chinese’ social media could be used for effective city branding. Finally, we conclude by discussing the implications of online social media use in China
Urban Heat Island monitoring with Global Navigation Satellite System (GNSS) data
Get PDFThe Urban Heat Island (UHI) effect occurs when the temperature in an urban area is higher than the temperature at a rural area. UHIs are monitored using remote sensing techniques such as satellite imagery or using temperature sensors de-ployed in a metropolitan area. In this chapter we propose a methodology to moni-tor the UHI intensity from Global Navigation Satellite Systems (GNSS) data. As the GNSS signal travels from the satellite to the receiver it propagates through the troposphere. A delay (Tropospheric delay) affects the signal. The delay is propor-tional to environmental variables. Also, the tropospheric delay in zenith direction (ZTD) is estimated as part of the Precise Point Positioning (PPP) technique. Therefore, in this chapter it is shown how to use process GNSS data to obtain ZTD and obtain temperature at an urban and a rural site simultaneously from the ZTD. The advantages of using GNSS data is its availability and many GNSS networks have been deployed in different cities so no need to deploy sensor net-works. Furthermore, GNSS signal is less affected by bad weather conditions than satellite imagery
Surface integrity in metal machining - Part I: Fundamentals of surface characteristics and formation mechanisms
Get PDFThe surface integrity of machined metal components is critical to their in-service functionality, longevity and overall performance. Surface defects induced by machining operations vary from the nano to macro scale, which cause microstructural, mechanical and chemical effects. Hence, they require advanced evaluation and post processing techniques. While surface integrity varies significantly across the range of machining processes, this paper explores the state-of-the-art of surface integrity research with an emphasis on their governing mechanisms and emerging evaluation approaches. In this review, removal mechanisms are grouped by their primary energy transfer mechanisms; mechanical, thermal and chemical based. Accordingly, the resultant multi-scale phenomena associated with metal machining are analyzed. The contribution of these material removal mechanisms to the workpiece surfaces/subsurface characteristics is reviewed. Post-processing options for the mitigation of induced surface defects are also discussed
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