Design and analysis of an antenna for batteryless transcranial direct current stimulation devices

The purpose of this study is to design a low-cost planar Archimedean dipole antenna for batteryless transcranial direct current stimulation devices. The antenna parameters including resonance frequency, radiation efficiency, radiation pattern, and gain are simulated using finite difference time domain based electromagnetic simulation software XFdtd. The proposed antenna is simulated with low-cost FR4 PCB substrate of thickness of 1.6 mm. The antenna is designed with half wavelength of resonant frequency and fed with a matching line. The target frequency band is the industrial, scientific and medical (ISM) band of 915 MHz which is in the simulated band width of 31 MHz (903-934MHz). Moreover, since the bio-effect of specific absorption rate by radio frequency electromagnetic wave for power harvesting is an important concern, we try to find out the safety limit. Thus a quantitative analysis of distributions of electric field and power absorption in anatomical human head model by the far field radio frequency energy received by our designed antenna has been presented.

Mobile devices in social contexts

The development of mobile devices has occurred with unprecedented pace since the late nineties, and the increase of generic services has proliferated in most developed countries, driven by the expanding technological capabilities and performance of mobile platforms. This dissertation investigates how consumer objectives, orientation and behavior can aid in explaining the adoption and use of a new type of mobile devices: "app phones". This dissertation focuses its effort on two focal influences of adoption and use; social influences and competing forces. Through a qualitative case study and field study this dissertation explores early adoption and use of iPhones. The case study is a one-shot cross-sectional case study that investigates five individuals, related through the same social network, and their decision to adopt an iPhone prior to its release in Denmark. This adoption decision engenders high switching costs as adopters lack references to imitate and need skills to unlock and jailbreak their iPhones to make them work on Danish networks. The specific purpose of the case study is to explore how social influences impact mobile users' early adoption decisions, as it is well known in the literature that people with similar characteristics, tastes, and beliefs often associate in the same social networks and, hence, influence each other. The field study is cross-sectional with multiple snapshots and explores fifteen individuals part of the same university study, who recieves an iPhone for a period of seven months short after its release in Denmark. The specific purpose of the field study is to explore how competing forces of iPhone usage influence assimilation, i.e. the degree to which the iPhone is used, over time. The dissertation is reported through four articles and is directed at both academic researchers and practitioners. The study emphasizes the importance of social influences and competing forces in the investigation of adoption and use of certain mobile devices.

Early adoption of mobile devices : a social network perspective

As mobile devices have become the personal information-processing interface of choice, many individuals seem to swiftly follow fashion. Yet, the literature is silent on how early adopters of mobile devices overcome uncertainties related to shifts in technology. Based on purposive sampling, this paper presents detailed insights into why and how five closely related individuals made the decision to adopt the iPhone before it was available through traditional supply chains. Focusing on the role played by social networks, we analyze how adoption threshold, opinion leaders, social contagion, and social learning shaped adoption behaviors and outcomes. The analyses confirm that network structures impact the early decision to accept the iPhone; they show that when facing uncertainty, adoption decisions emerged as a combined result of individual adoption reflections and major influences from the social network as well as behaviors observed within the network, and, they reveal interesting behaviors that differed from expectations. In conclusion, we discuss implications for both theory and practice.

Early adoption of mobile devices : a social network perspective

As mobile devices have become the personal information-processing interface of choice, many individuals seem to swiftly follow fashion. Yet, the literature is silent on how early adopters of mobile devices overcome uncertainties related to shifts in technology. Based on purposive sampling, this paper presents detailed insights into why and how five closely related individuals made the decision to adopt the iPhone before it was available through traditional supply chains. Focusing on the role played by social networks, we analyze how adoption threshold, opinion leaders, social contagion, and social learning shaped adoption behaviors and outcomes. The analyses confirm that network structures impacted the early decision to accept the iPhone; they show that when facing uncertainty, adoption decisions emerged as a combined result of individual adoption reflections and major influences from the social network as well as behaviors observed within the network; and, they reveal interesting behaviors that differed from expectations. In conclusion, we discuss implications for both theory and practice.

Using internet enabled mobile devices and social networking technologies to promote exercise as an intervention for young first episode psychosis patients

Young people with first episode psychosis are at an increased risk for a range of poor health outcomes. In contrast to the growing body of evidence that suggests that exercise therapy may benefit the physical and mental health of people diagnosed with schizophrenia, there are no studies to date that have sought to extend the use of exercise therapy among patients with first episode psychosis. The aim of the study is to test the feasibility and acceptability of an exercise program that will be delivered via internet enabled mobile devices and social networking technologies among young people with first episode psychosis.

Teaching in the iWorld: developing a repertoire of pedagogical discourse around the usage of touch screen devices in early years classrooms

 Touch-screen devices have been enthusiastically adopted by schools across Australia and Canada. Their ease of use means that they are accessible by very young children, and these children often have free access to these devices in their home, however the devices tend to be ‘domesticated’ in the school context (O’Mara and Laidlaw, 2011). In the short period of their availability, a plethora of educational applications have been developed for these devices. This paper addresses emergent themes from our 2011-2013 Canadian/Australian project, Literacy learning in playful spaces: using multi-modal strategies to develop narrative with young learners, funded by the Canadian Social Sciences and Humanities Research Council (Insight Development Grant). In our analysis of the discourse around the introduction of portable touch screen devices into school literacy classes (published texts, teacher interviews, classroom observations), we noted that much of the public discourse is slanted towards the idea of “teacher-proofing” the curriculum. Initially the teachers we have been working with saw the apps themselves as complete, as doing all the work and the discourse around the devices was around what apps are “best”, and “is there an app for that?” It was only with more experience and time that teachers were able to harness the range of affordances of the devices—their capacity for recording audio, video, pictures etc., and start to categorise the apps themselves. In this paper we suggest ways in which current literacy models might be used to develop a repertoire of pedagogical discourse around these devices, providing language and framings for teachers to think about how these new tools might best be used to enhance literacy teaching and learning. O’Mara, J. & Laidlaw, L. (2011). Living in the iWorld: Two literacy researchers reflect on the changing texts and literacy practices of childhood. English Teaching: Practice and Critique 10 (4): 149-159. Available: http://edlinked.soe.waikato.ac.nz/research/journal/view.php?article=true&id=754&p=1

Nanostructured transition metal oxynitrides for energy storage devices

 In this work, transition metal oxynitrides are investigated as candidates for applications in energy storage devices. More specifically, their performance in supercapacitors and in metal-air batteries is explored.

Nonlinear dynamic modeling of ionic polymer conductive network composite actuators using rigid finite element method

Ionic polymer conductive network composite (IPCNC) actuators are a class of electroactive polymer composites that exhibit some interesting electromechanical characteristics such as low voltage actuation, large displacements, and benefit from low density and elastic modulus. Thus, these emerging materials have potential applications in biomimetic and biomedical devices. Whereas significant efforts have been directed toward the development of IPMC actuators, the establishment of a proper mathematical model that could effectively predict the actuators' dynamic behavior is still a key challenge. This paper presents development of an effective modeling strategy for dynamic analysis of IPCNC actuators undergoing large bending deformations. The proposed model is composed of two parts, namely electrical and mechanical dynamic models. The electrical model describes the actuator as a resistive-capacitive (RC) transmission line, whereas the mechanical model describes the actuator as a system of rigid links connected by spring-damping elements. The proposed modeling approach is validated by experimental data, and the results are discussed. © 2014 Elsevier B.V. All rights reserved.

Efficient design of polarization insensitive polymer optical waveguide devices considering stress-induced effects

We present an approach for the efficient design of polarization insensitive polymeric optical waveguide devices considering stress-induced effects. In this approach, the stresses induced in the waveguide during the fabrication process are estimated first using a more realistic model in the finite element analysis. Then we determine the perturbations in the material refractive indices caused by the stress-optic effect. It is observed that the stresses cause non-uniform optical anisotropy in the waveguide materials, which is then incorporated in the modal analysis considering a multilayer structure of waveguide. The approach is exploited in the design of a Bragg grating on strip waveguide. Excellent agreement between calculated and published experimental results confirms the feasibility of our approach in the accurate design of polarization insensitive polymer waveguide devices.