Super-twisting observer-based sliding mode control with fuzzy variable gains and its applications to fully-actuated hexarotors

In this paper, we consider the super-twisting observer-based sliding mode control algorithm with fuzzy variable gains (STOSMC) for the fully-actuated hexarotor. Our hexarotor has full actuation due to six titled propellers that allows to control position and orientation (attitude) simultaneously, and resolves the singularity problem of the rotational matrix by using the quaternion modeling framework. We show that the proposed STOSMC for the hexarotor guarantees finite-time convergence of the estimation error and asymptotic stability of the hexarotor. In simulations, we demonstrate the nonsingularity and fully-actuated control performance of the hexarotor by considering extreme position and attitude control scenarios. Moreover, the simulation results show that the hexarotor achieves the fast and precise tracking performance to the desired position and the desired attitude and the chattering phenomenon is reduced compared with the fixed-gains observer-based super-twisting sliding mode control due to the fuzzy mechanism.     

Assessing volunteer satisfaction at the London Olympic Games and its impact on future volunteer behaviour

Abstract

In recent years, volunteering has received strong research attention from both scholars and practitioners. For the most part, involvement in volunteer activities has been identified as an important determinant of future volunteering. Through revalidating an existing instrument, the purpose of this study was to assess the dimensions of volunteer satisfaction at the 2012 London Olympic Games and its impact on future volunteer behaviour. The findings of this study shed light on the identification of volunteer satisfaction factors in the mega sporting event setting, particularly for a unique type of volunteer (i.e. media worker) assigned to a special set of tasks. Unlike Galindo-Kuhn and Guzley’s results that revealed participation efficacy and group integration to be strong predictors of volunteer satisfaction, organizational support was the primary predictor for media centre volunteers’ re-participation intention towards future volunteering programmes.     

Platform War vs. Platform Synergy? A Longitudinal Analysis of Media Substitution between Personal Computers and Mobile Devices

ABSTRACT

Research on media substitution theory has examined substitutional and/or complementary relationships between new and existing media. This study focuses on the growth of mobile platforms and investigates the relationship between mobile devices and personal computers. Using Nielsen’s panel data that provide electronically recorded media usage (N = 2,396), this study analyzes yearly changes in time allocation to mobile devices and PCs at total and content-specific usage levels during mobile 4G transition. Results suggest a complementarity dynamic between mobile devices and PCs; however, the patterns were more nuanced in light of the role of individual and structural factors when determining media choice.     

SVC bitstream adaptation in MPEG-21 multimedia framework

INTRODUCTION Scalable video coding (SVC) (Schwarz et al., 2004) is the most promising video format for appli- cations of collaborative communication. First, SVC format, which is extended from the latest advanced video coding (AVC), is appropriate for creating a wide variety of bitrates with high compression effi- ciency. Second, an original SVC bitstream can be easily truncated in different ways to meet various characteristics and variations of devices and connec- tions. The scalabil…     

Efficient distributed selective search

Simulation and analysis have shown that selective search can reduce the cost of large-scale distributed information retrieval. By partitioning the collection into small topical shards, and then using a resource ranking algorithm to choose a subset of shards to search for each query, fewer postings are evaluated. In this paper we extend the study of selective search into new areas using a fine-grained simulation, examining the difference in efficiency when term-based and sample-based resource selection algorithms are used; measuring the effect of two policies for assigning index shards to machines; and exploring the benefits of index-spreading and mirroring as the number of deployed machines is varied. Results obtained for two large datasets and four large query logs confirm that selective search is significantly more efficient than conventional distributed search architectures and can handle higher query rates. Furthermore, we demonstrate that selective search can be tuned to avoid bottlenecks, and thus maximize usage of the underlying computer hardware.     

A moderated mediation model of political collective action in Hong Kong: examining the roles of social media consumption and social identity

Adopting a communication mediation approach, this study explores the role of overall social networking service (SNS) use in facilitating people’s participation in collective political action through the mediation of online and offline political discussions. The study also underscores the moderating effect on the mediation process of both social identity and geographical origin. Moderated mediation analyses reveal that the positive impact of overall SNS use on participation mediated by offline discussion is stronger for people with higher Hong Kong identity and for people from Hong Kong. This moderated mediation model specifies the socio-psychological mechanism of participation in collective political action in an immigrant society such as Hong Kong.     

Employees’ perceptions of interpersonal competence: The case of South Korea

This study examined employees’ perceptions of interpersonal competence at work through the research methodology known as concept mapping. The purpose of this study was to identify the phenomenally derived components of interpersonal competence in work environments and employees’ underlying cognitive structures of interpersonal competence at work. Multidimensional scaling analysis indicated that the participants conceptualized interpersonal competence in the following two dimensions: (i) work-specific domain versus general domain and (ii) unilateral domain versus bilateral domain. In addition, hierarchical clustering on the MDS coordinates produced six clusters: Caring & Considerate, Sociable & Out-going, Kind & Gentle, Reliable & Leadership skills, and Confident & Responsible. Our results were discussed with respect to future research and educational approaches to the issues surrounding interpersonal competencies at work.     

AWARE: A Personalized Normative Feedback–Based Group Intervention for Mandated College Students

AWARE is a brief group intervention that was built upon the principles of personalized normative feedback with novel components (Penn State Altoona, n.d.). The purpose of this study was to pilot test the intervention with mandated college students who were referred for alcohol‐related violations (N = 283). Results showed significant postintervention changes. Significant interaction effects between time and race and between time and gender were found. Reduction in the consumption of alcohol use and perception of peer alcohol use were significantly different among non‐White and female participants.     

Effects of motivational and volitional email messages (MVEM) with personal messages on undergraduate students' motivation, study habits and achievement

This study investigated what kind of supportive information can be effective in improving the situation where there were severe motivational challenges. Motivational and volitional email messages (MVEM) were constructed based on an integrated model of four theories and methods, which are Keller's ARCS model, Kuhl's action control theory, Gollwitzer's Rubicon model of motivation and volition, and Visser & Keller's strategy of motivational messages, and distributed with personal messages created based on audience analysis to a large undergraduate class. In order to examine the effects of the messages on motivation for the course, study habits (study time), and achievement (test grade), MVEM were sent to 30 students (Personal Message Group: PMG) with personal messages and to 71 students (Non‐Personal Message Group: NonPMG) without personal messages. Results indicated that PMG showed a higher level of motivation, especially in regard to confidence, than NonPMG. Also, the mean test grade of PMG increased so that the initial difference of the test grade between the two groups significantly decreased. Although there was no difference between the two groups in study habits, the findings suggest that personal messages addressing specific individual problems raise the positive effects of MVEM constructed based on the integrated model. Future research directions are discussed.     

‘Forgotten’ democracy,student activism,and higher education in Myanmar: past,present, and future

Asia Pacific Education Review - This paper is a historical examination of higher education in contemporary Myanmar, and its relationship to the students, the most important and visible actor in...