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Mobile Applications (mobile + application)
Selected AbstractsScheduling time-critical requests for multiple data objects in on-demand broadcastCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 15 2010Victor C. S. Lee Abstract On-demand broadcast is an effective data dissemination approach in mobile computing environments. Most of the recent studies on on-demand data broadcast assume that clients request only a single-data-object at a time. This assumption may not be practical for the increasingly sophisticated mobile applications. In this paper, we investigate the scheduling problem of time-critical requests for multiple data objects in on-demand broadcast environments and observe that existing scheduling algorithms designed for single-data-object requests perform unsatisfactorily in this new setting. Based on our analysis, we propose new algorithms to improve the system performance. Copyright © 2010 John Wiley & Sons, Ltd. [source] PEFC Stack Operating in Anodic Dead End Mode,FUEL CELLS, Issue 4 2004L. Dumercy Abstract The polymer electrolyte fuel cell,(PEFC) system is considered as an alternative power source and is particularly promising for mobile applications. This paper reports some experimental results performed on a PEFC stack, operating in anodic dead end mode. The flush frequency of the anode is investigated. In order to reduce hydrogen consumption in an embedded application, the flush frequency could be calculated from system modelling, according to the operating conditions. The first step of such a model is presented. It simulates the water exchanges between the anode and cathode channels in the anode dead end case. It has been implemented in a MATLAB® environment. [source] Performance analysis of data scheduling algorithms for multi-item requests in multi-channel broadcast environmentsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2010Kai Liu Abstract Nowadays querying multiple-dependent data items in a request is common in many advanced mobile applications, such as traffic information enquiry services. In addition, multi-channel architectures are widely deployed in many data dissemination systems. In this paper, we extend a number of data productivity-based scheduling algorithms and evaluate their performance in scheduling multi-item requests in multi-channel broadcast environments. We observe from the experimental results two performance problems that render these algorithms ineffective. Lastly, we discuss possible causes of these problems to give insights in the design of a better solution. Copyright © 2009 John Wiley & Sons, Ltd. [source] Overview of DVB-RCS+M and its developmentINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 3-4 2010Harald Skinnemoen Abstract The use of DVB-S and DVB-RCS for conducting two-way communications from small satellite terminals has become well established in Europe and elsewhere. During the development of DVB-RCS the possibility of limited use for satellite terminals that were moving was considered in January 2004 and incorporated into the Guideline document associated with the Standard in April 2005. It was noted, however, that this matter could be addressed further as a future development. This paper addresses the steps that have been taken since then to realize this objective. During the last few years, it has been shown that the DVB-S2/DVB-RCS specifications are good candidate baselines for the efficient implementation of broadband services to mobile users. Results of these studies were gathered in a study mission report from the TM-RCS ad hoc group. It was demonstrated that both forward and return channel waveforms are impacted by the mobile usage, and should be addressed in the scope of an update of the DVB-RCS standard. Technical analysis identified that DVB-RCS, as it had been originally designed for fixed satellite services, provided most of the features required by mobile applications above 5,GHz, and could be turned into a competitive solution with a few carefully crafted modifications. Subsequent activities within the TM-RCS Group have led to an efficient and robust standard that incorporates mobility more definitely into version 1.5.1 of the DVB-RCS specifications, along with appropriate detailed ,Guidelines' documentation giving expanded description of the standard and its use and application. Copyright © 2009 John Wiley & Sons, Ltd. [source] Evaluation of a mobile learning organiser for university studentsJOURNAL OF COMPUTER ASSISTED LEARNING, Issue 3 2005Dan Corlett Abstract This paper describes a 10-month trial of a mobile learning organiser, developed for use by university students. Implemented on a wireless-enabled Pocket PC hand-held computer, the organiser makes use of existing mobile applications as well as tools designed specifically for students to manage their learning. The trial set out to identify the most-used tools for such a learning device and their patterns and problems of usage. The primary uses of the organiser were communication, time-management and access to content. No single application took precedence. The results from an analysis of questionnaire surveys and focus groups indicate that there was a demand for institutional support of mobile learning, in particular to provide course content and timetabling information. Wireless connectivity was crucial to the usefulness of the organiser. Usability issues relating to the hardware and software had considerable impact on the students' usage and satisfaction with the system. [source] Multiband MIMO antenna with independent resonance frequency adjustabilityMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2010Min-Seok Han Abstract A compact multiband multiple-input multiple-output (MIMO) antenna with a band stop matching circuit for next generation mobile applications is proposed. The proposed multiband MIMO antenna consists of two dual-band planar inverted-F antennas, which provide wideband characteristics. To improve the isolation characteristic at the long term evolution band, a band stop matching circuit was inserted at the corner of each antenna element. The proposed MIMO antenna has isolation of ,15 dB at the lower band and over 20 dB at the upper band. In addition, the resonant frequencies of the proposed MIMO antenna can be independently tuned by changing the value of the inductor or by adjusting the widths of Slit1 and Slit2. To evaluate the performance of the proposed antenna, key performance parameters such as total efficiency, envelope correlation coefficient, mean effective gain (MEG), and the MEG ratio are analyzed. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1893,1901, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25334 [source] More stabilized triple-band antenna with a rolled radiating arm and a metallic rod for mobile applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2009Xingyu Zhang Abstract In this article, a compact design of a flexible planar inverted-F antenna (PIFA) is proposed for triple-band (GSM/DCS/PCS) mobile phone application. The main radiating element of the antenna, which generates the GSM and DCS resonant modes, is printed on a flexible printed circuit board (FPCB) and rolled in a form of cylinder. To improve the construction stability of the antenna, a metallic rod is inserted into the centre of the rolled antenna. The metallic rod acting as a parasitic element of the antenna also generates the PCS resonant mode. The antenna prototype was fabricated and measured. Good agreement between the measurement and simulation results is obtained. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 891,894, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24197 [source] Integration of internal 700 MHz and WLAN/WiMAX antennas for palm-sized mobile devicesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2008Jui-Hung Chou Abstract Two promising, internal, shorted monopole antennas for 700 MHz and WLAN/WiMAX operation are combined in an arrangement with minimized mutual coupling for palm-sized mobile applications. The two stamped, metal-plate antennas with a 2-mm gap therein between can be integrated into a compact configuration and are then mounted near one side of the system circuit board. With the suitable shorting locations and arrangement of the two antennas, good isolation (S21 < ,20 dB) between the two ports can easily be obtained. Analysis of placing a CCD shielding cylinder between the two antennas and the two shorting strips joined to form a shorting wall are also conducted. Detailed designs of the two antennas are described, and the results thereof are discussed. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2948,2951, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23833 [source] Polymers as functional components in batteries and fuel cells,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9-10 2006Gerhard Wegner Abstract The recent 10 years have seen an unprecedented development in the area of portable electronic devices: mobile phones, laptops, PDAS, and digital cameras have all become commodities on a large scale. All of these devices need a power supply in terms of a battery acceptable capacity, possibly rechargeable. This demand has triggered research and development in polymer materials science for lithium ion conducting polymers that could replace or avoid organic liquids as a supporting electrolyte. Moreover, polymers need to be optimized that act in the form of "gels" as framework and/or membrane materials to achieve mechanical integrity of the electrode compartments. Ionic conductivity for protons in polymeric systems is also the key issue in the development of so-called polyelectrolyte-membrane fuel cells (PEMFCs) that are supposed to work as power sources for mobile applications, e.g. in hybrid cars. A liquid fuel such as methanol would be converted to CO2 and H2O with concomitant production of electricity. Novel proton conducting polymer systems are required that work at temperatures between 150,200°C, that is under more or less water-free conditions. These requirements find an echo in the academic world in terms of renewed interest in the mechanisms of ionic transport phenomena in polymeric systems and in studies that aim for optimization of materials. In this article there will be a report on both lithium-ion and proton conducting polymers that have been recently developed in the authors' laboratory. The results will be discussed in the context of the demands that need to be met for advanced technologies. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||