Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges

With the rapid development of marine activities, there has been an increasing number of maritime mobile terminals, as well as a growing demand for high-speed and ultra-reliable maritime communications to keep them connected. Traditionally, the maritime Internet of Things (IoT) is enabled by maritime satellites. However, satellites are seriously restricted by their high latency and relatively low data rate. As an alternative, shore & island-based base stations (BSs) can be built to extend the coverage of terrestrial networks using fourth-generation (4G), fifth-generation (5G), and beyond 5G services. Unmanned aerial vehicles can also be exploited to serve as aerial maritime BSs. Despite of all these approaches, there are still open issues for an efficient maritime communication network (MCN). For example, due to the complicated electromagnetic propagation environment, the limited geometrically available BS sites, and rigorous service demands from mission-critical applications, conventional communication and networking theories and methods should be tailored for maritime scenarios. Towards this end, we provide a survey on the demand for maritime communications, the state-of-the-art MCNs, and key technologies for enhancing transmission efficiency, extending network coverage, and provisioning maritime-specific services. Future challenges in developing an environment-aware, service-driven, and integrated satellite-air-ground MCN to be smart enough to utilize external auxiliary information, e.g., sea state and atmosphere conditions, are also discussed

THE EFFECTS OF LEARNING STYLES AND MODELING TECHNIQUES ON REQUIREMENT DOCUMENTATION PERFORMANCE

The present study examines the effect of Individual Learning Style on modeling functional requirements. To-date, there is noevidence that individual cognitive learning styles are related to modeling ability in novice systems analysts. The results ofthis study indicate that in teaching functional requirement techniques, novices with abstract learning styles perform as well asthose with concrete learning styles

Soft Methodology for Cost-and-error Sensitive Classification

Many real-world data mining applications need varying cost for different types of classification errors and thus call for cost-sensitive classification algorithms. Existing algorithms for cost-sensitive classification are successful in terms of minimizing the cost, but can result in a high error rate as the trade-off. The high error rate holds back the practical use of those algorithms. In this paper, we propose a novel cost-sensitive classification methodology that takes both the cost and the error rate into account. The methodology, called soft cost-sensitive classification, is established from a multicriteria optimization problem of the cost and the error rate, and can be viewed as regularizing cost-sensitive classification with the error rate. The simple methodology allows immediate improvements of existing cost-sensitive classification algorithms. Experiments on the benchmark and the real-world data sets show that our proposed methodology indeed achieves lower test error rates and similar (sometimes lower) test costs than existing cost-sensitive classification algorithms. We also demonstrate that the methodology can be extended for considering the weighted error rate instead of the original error rate. This extension is useful for tackling unbalanced classification problems.Comment: A shorter version appeared in KDD '1

Minimisation of Non-periodic Preventive Maintenance Cost in Series-Parallel Systems

A new method to optimise the non-periodic preventive maintenance model of a series-parallel system is proposed. A two-stage algorithm that incorporates the failure limit policy to determine maintenance components, maintenance times, and total maintenance cost is suggested. When the reliability of the system  reaches a threshold value, preventive maintenance is performed. The first stage identifies the parallel subsystem required to be maintained, while the second stage determines the component required to be maintained in the parallel sub-system. A unit-cost life index (UCL) has been developed to evaluate the extent to which maintaining a component extends the life of a system for the parallel subsystem. Three simulated cases demonstrate the effectiveness and the practicality of the proposed method in optimising the non-periodic preventive maintenance model of a series-parallel system.Defence Science Journal, 2011, 61(1), pp.44-50, DOI:http://dx.doi.org/10.14429/dsj.61.6

Teaching Business Intelligent with an Executive Dashboard

Data visualization has been an important tool for company executives to obtain timely information for decision making purposes. This tutorial session use a state-of-art executive dashboard system to showcase how data visualization can be presented in a classroom environment. Sample cases and datasets are available for participants to take home for their own teaching purposes

Sharing is the Key to Create a Community of Learning in Higher Education

Web 2.0 technologies have been wildly used in pedagogical design. It is eminent to adopt a new way of teaching and learning in the higher education environment. This paper advocate that “Sharing” is the essence of this new paradigm shift. We borrow from the Community of Learning theory and try to argue that content sharing within the faculty members, between faculty members and students, and among students are one important element to deliver high quality education. We also use our experience of designing an undergraduate MIS course to share a few techniques of using Web 2.0 technology in the classroom, virtual or on the ground

A Comparative Study on Spin-Orbit Torque Efficiencies from W/ferromagnetic and W/ferrimagnetic Heterostructures

It has been shown that W in its resistive form possesses the largest spin-Hall ratio among all heavy transition metals, which makes it a good candidate for generating efficient dampinglike spin-orbit torque (DL-SOT) acting upon adjacent ferromagnetic or ferrimagnetic (FM) layer. Here we provide a systematic study on the spin transport properties of W/FM magnetic heterostructures with the FM layer being ferromagnetic Co$_{20}$Fe$_{60}$B$_{20}$ or ferrimagnetic Co$_{63}$Tb$_{37}$ with perpendicular magnetic anisotropy. The DL-SOT efficiency $|\xi_{DL}|$, which is characterized by a current-induced hysteresis loop shift method, is found to be correlated to the microstructure of W buffer layer in both W/Co$_{20}$Fe$_{60}$B$_{20}$ and W/Co$_{63}$Tb$_{37}$ systems. Maximum values of $|\xi_{DL}|\approx 0.144$ and $|\xi_{DL}|\approx 0.116$ are achieved when the W layer is partially amorphous in the W/Co$_{20}$Fe$_{60}$B$_{20}$ and W/Co$_{63}$Tb$_{37}$ heterostructures, respectively. Our results suggest that the spin Hall effect from resistive phase of W can be utilized to effectively control both ferromagnetic and ferrimagnetic layers through a DL-SOT mechanism

The Role Of Project Success In The Relationship Between Accountability And IS Process Documentation

We report on an experimental study of the impact of outcome bias and accountability on documentation decisions.  The subjects, working on an information system development project, decided on how much of the process details (both good and bad) known only to the project team, would be made part of an intra-organizational knowledge database. We find that outcome bias has a significant influence on decisions. Managers of “failure” projects were more inclined to report more of the bad process details than managers of “successful” projects, consistent with attribution theory.