Distributed Time-Sensitive Task Selection in Mobile Crowdsensing

With the rich set of embedded sensors installed in smartphones and the large number of mobile users, we witness the emergence of many innovative commercial mobile crowdsensing applications that combine the power of mobile technology with crowdsourcing to deliver time-sensitive and location-dependent information to their customers. Motivated by these real-world applications, we consider the task selection problem for heterogeneous users with different initial locations, movement costs, movement speeds, and reputation levels. Computing the social surplus maximization task allocation turns out to be an NP-hard problem. Hence we focus on the distributed case, and propose an asynchronous and distributed task selection (ADTS) algorithm to help the users plan their task selections on their own. We prove the convergence of the algorithm, and further characterize the computation time for users' updates in the algorithm. Simulation results suggest that the ADTS scheme achieves the highest Jain's fairness index and coverage comparing with several benchmark algorithms, while yielding similar user payoff to a greedy centralized benchmark. Finally, we illustrate how mobile users coordinate under the ADTS scheme based on some practical movement time data derived from Google Maps

How science, technology, engineering, mathematics (STEM) project-based learning improves student learning

The purpose of this paper is to examine how extra-curricular and academic performance is affected by student participation in Science, Technology, Engineering and Mathematics (STEM) under project-based learning (PBL) activities. General observation and quantitative analysis was used to evaluate the two aspects. A solar car team project under the philosophy of STEM and PBL is developed and more than two hundred students from electrical and mechanical engineering field participated in the team project and learnt the STEM PBL core value. The team aims to develop a solar-powered vehicle to demonstrate the viability of a renewable energy through the use of green transportation, to promote the awareness of environmental sustainability among the public. It also provides students with an opportunity to put theoretical knowledge into practice, gain hands-on experience, and practice project management skills during development, and thus leading student to understanding science and new technology; and practising engineering skills and mathematics. Till now, six solar vehicles were built with the massive efforts of students. Moreover, design thinking process is adopted to engage and motivate students to learn and develop in the team. The entire process includes the following steps: ‘Empathize’, allowing students to learn about their audience for their designing process; ‘Define’, constructing a point of view that is based on user needs and insights; ‘Ideate’, brainstorming and coming up with creative solutions; ‘Prototype’, building a rePresentation of one or more of student ideas to show to others and ‘test’, returning to original user group and testing their ideas for feedback. The team students showed significantly growth rates on research, planning, project implementation and reporting. The team also assists students’ further STEM studies and STEM career planning, and the nurturing of diversified talents with a range of capabilities at different levels in STEM knowledge development. In addition, the team organizes solar car workshops and demonstrations, and supervises group projects for secondary school students. Result of the study implied that STEM with PBL in school benefitted students in that they achieved a greater extension on extra-curricular and academic aspect, especially gaining more solid knowledge in technology and engineering

Participation and reporting in participatory sensing

Abstract-In participatory sensing (PS), users use smartphones to collect information related to a certain phenomenon of interest, and report their sensed data to the service provider through cellular or Wi-Fi networks. Previous studies on the incentive mechanism design for user participation often neglect the details of data reporting, which is non-trivial given the user mobility, location-dependent network availability, and transmission cost. In this paper, we study the decisions of the service provider and the users in PS applications that involve photo or video transmissions, where the reporting cost through the cellular network is nonnegligible. The service provider uses a deadline reward scheme to motivate users to participate, and optimizes its reward to maximize its expected surplus. Users make their participation and reporting decisions based on the reward announced by the service provider. We jointly consider the user mobility and multiple access methods with different transmission costs and location heterogeneity in the problem formulation and analysis. For the general case with a time-discounted reward, we formulate a user's reporting decision problem as a sequential decision problem, and propose an optimal participation and reporting decisions (OPRD) algorithm using dynamic programming. For the special case with a fixed reward, we derive the closed-form participation and reporting decisions. Simulation results show that the OPRD algorithm improves the user payoff over the patient and impatient schemes by 9.8% and 13.2%, respectively

An Unexpected Cause of a Subcutaneous Nodule: A Case Report of Dirofilaria Infection

Humans are not natural hosts of Dirofilaria; however, pulmonary or subcutaneous infections may occur through mosquitoes transmission. Patients presenting with simple subcutaneous nodules may not seek early medical attention, and hence systemic involvement through hematogenous spread may occur. Definitive diagnosis of Dirofilaria infection is made by histopathological examinations of the infected tissues. We report a patient with an incidental diagnosis of Dirofilaria infection confirmed by histopathological findings of a subcutaneous nodule on the right thigh. The source of infection remains unknown