Dynamic Control of Local Field Emission Current from Carbon Nanowalls

We report on a systematic study of modulation of the field emission current from carbon nanowalls using a sharp probe as the anode in an ultrahigh vacuum system. Modulation of the local emission current was achieved by either varying the anode-cathode distance (d) with the aid of an AC magnetic field or superimposing a small AC bias on a DC bias during the field emission measurement. Current modulation ratio of over two orders of magnitude was achieved with the modulation becoming more efficient at a smaller d. The experimental results are discussed using the Fowler-Nordheim theory in combination with a simple cantilever model to account for the modulation effect. The experimental results demonstrated good static stability and dynamic controllability of local field emission current from the carbon nanowalls

HOW CAN THE HISTORY MUSEUMS BE ENGAGING FOR GENERATION Z? -A MOBILE APP WHICH CAN COLLECT HISTORICAL STORIES FROM HISTORY MUSEUMS

The museum is a cultural place for people to broaden their horizons and it is also an essential environment for informal learning. However, due to our fast-paced lifestyle and diverse forms of entertainment, needs are increasingly varied, and museums face many challenges. Many people, especially young people like Generation Z (a group of people who were born between the mid-1990s to the mid-2000s), are not interested in static exhibitions with tedious and wordy interpretations. Therefore, building the connection between Generation Z and making history museums more engaging is crucial. The goal of my project is to identify the engaging elements for Generation Z and apply them to a design intervention for building connections between Generation Z and history museums. According to my literature review, online survey, and a walking interview, there are three key findings which can drive my design intervention: (1) Gen Z thinks that use of heavy text and lack of interaction are disengagement elements. They believe that creating memories related to history can help them to generate empathy and increase their interest in history. (2) Gen Z is active on social media platforms such as Snapchat, Instagram and they enjoy watching “stories,” which is a visual scrapbook of videos and photos that disappear after 24 hours. (3) Gamification (a method to incorporate the elements of a game into a non-gaming environment) can help individuals to learn and absorb knowledge. Rewards, self-expression, altruism, storytelling and visual communication are crucial gamification elements which can make individuals feel more engaged in the learning environment. I developed three generation prototypes and had participants interact with them to gain feedback from my target group. Finally, the overall design outcome is a location-based mobile application called MUZE which can collect historical stories in daily life. The app has three features: the ability to collect historical stories, the ability to share feelings and thoughts about the history in the form of a short video, and the ability to redeem virtual or physical rewards related to the history museums

Design and analysis of magnetic circuit of permanent magnet eddy current brake

The eddy current brake has the advantages of no frictional contact or hydraulic fluid, high structural reliability, etc. The existing linear eddy current brakes are mostly flat type. A cylindrical permanent magnet eddy current brake is proposed in this paper, whose air gap magnetic field is generated by a series of ring-shaped permanent magnets and guided by iron pole to conductor layers, and can achieve higher air gap magnetic flux density. This paper introduces its basic structure and working principle. In order to obtain the analytical model of magnetic circuit design, the equivalent magnetic circuit method is used to analyze and derive the magnetic circuit, and it is verified by the axisymmetric finite element model. To derive the braking force generated by the eddy current brake, the layer theory approach is applied. The influence of electromagnetic parameters on the force characteristic is obtained by finite element numerical calculation, which provides a theoretical basis for the optimal design of the eddy current brake

CA Humor: Its Role in Service Recovery and Continued Use

Conversational agents (CAs) for customer service are gaining popularity, but frequently suffer from service failures. Thus, designing effective CA service recovery strategies is crucial for their adoption and continued use. Here, prior work has mostly examined symbolic recovery strategies of CA apology, empathy, and appreciation. Another such strategy, CA humor, can potentially mitigate service failures, but there is limited understanding of its role. Motivated thus, we draw on attribution theory to explain the role of CA humor in service recovery from a responsibility attribution perspective. We propose a theoretical model where CA humor influences customer’s responsibility attribution for failure via CA’s perceived intelligence and perceived enjoyment, which in turn impacts CA service satisfaction and continued usage intention. We design a lab experiment to test the model. We contribute to research on CA’s- adoption and continued use for customer service by explicating the role of a novel recovery strategy i.e., CA humor, which will be tested in our future work

Self-current induced spin-orbit torque in FeMn/Pt multilayers

Extensive efforts have been devoted to the study of spin-orbit torque in ferromagnetic metal/heavy metal bilayers and exploitation of it for magnetization switching using an in-plane current. As the spin-orbit torque is inversely proportional to the thickness of the ferromagnetic layer, sizable effect has only been realized in bilayers with an ultrathin ferromagnetic layer. Here we demonstrate that, by stacking ultrathin Pt and FeMn alternately, both ferromagnetic properties and current induced spin-orbit torque can be achieved in FeMn/Pt multilayers without any constraint on its total thickness. The critical behavior of these multilayers follows closely three-dimensional Heisenberg model with a finite Curie temperature distribution. The spin torque effective field is about 4 times larger than that of NiFe/Pt bilayer with a same equivalent NiFe thickness. The self-current generated spin torque is able to switch the magnetization reversibly without the need for an external field or a thick heavy metal layer. The removal of both thickness constraint and necessity of using an adjacent heavy metal layer opens new possibilities for exploiting spin-orbit torque for practical applications.Comment: 28 pages, 5 figure

STUDY OF SPIN CURRENT EFFECT IN METALLIC ANTIFERROMAGNET AND HEAVY METAL HETEROSTRUCTURES

Ph.DDOCTOR OF PHILOSOPH