Small Mobile Devices Research Articles

Study on the NAND Flash Memory-Based Failure Recovery Improvement Using T*-Tree

As compared to other types of flash memory, NAND flash memory is attracting attention as the next generation storage device for its low power use and fast access speed, which make it suitable for ubiquitous and mobile environment. In particular, flash memory is being used in storage devices in many fields, including the memory system of small mobile devices, as well as SSD (solid state disk) of large memory. Active research is underway for the efficient use of flash memory. However, NAND flash memory based storage devices exhibit unique hardware characteristics, such as erasing structure, and the B-tree index structure causes performance degradation when repeated writing requests are made. In order to enhance these problems, the present paper proposes to use NAND flash memory-based failure recovery improvement technique using the T*-tree. After conducting performance evaluation of the proposed technique and the existing technique, the proposed technique was found to be more efficient in its performance by 69%, compared to the existing technique.

Indoor MIMO Visible Light Communications: Novel Angle Diversity Receivers for Mobile Users

This paper proposes two novel and practical designs of angle diversity receivers to achieve multiple-input-multiple-output (MIMO) capacity for indoor visible light communications (VLC). Both designs are easy to construct and suitable for small mobile devices. By using light emitting diodes for both illumination and data transmission, our receiver designs consist of multiple photodetectors (PDs), which are oriented with different inclination angles to achieve high-rank MIMO channels and can be closely packed without the requirement of spatial separation. Due to the orientations of the PDs, the proposed receiver designs are named pyramid receiver (PR) and hemispheric receiver (HR). In a PR, the normal vectors of PDs are chosen the same as the normal vectors of the triangle faces of a pyramid with equilateral $N$ -gon base. On the other hand, the idea behind HR is to evenly distribute the PDs on a hemisphere. Through analytical investigation, simulations and experiments, the channel capacity and bit-error-rate (BER) performance under various settings are presented to show that our receiver designs are practical and promising for enabling VLC-MIMO. In comparison to induced link-blocked receiver, our designs do not require any hardware adjustment at the receiver from location to location so that they can support user mobility. Besides, their channel capacities and BER performance are quite close to that of link-blocked receiver. Meanwhile, they substantially outperform spatially-separated receiver. This study reveals that using angle diversity to build VLC-MIMO system is very promising.

Research on Piezoelectric Generators for Vibration Energy Harvesting

Ambient energy harvesting has been in recent years the recurring object of a number of research efforts aimed at providing an autonomous solution to the powering of small scale electronic mobile devices. Among the different solutions, vibration energy harvesting has played a major role due to the almost universal presence of mechanical vibrations. In the paper, a piezoelectric cantilever device for harvesting the ambient low-frequency vibration energy is designed, and influences of its structure on output voltage and power generation capacity are studied also. The study results show that the piezoelectric cantilever can produce enough power energy which meets the operation requirements of sensors in wireless networks. It provides a method and corresponding theoretical basis for the harvesting of ambient low-frequency vibration energy and the design of self-supply devices for sensors in wireless networks.

Evaluation of Novel Hand‐held Wireless Bioelectrical Impedance Analysis (BIA) Body Composition Devices

Body fat and skeletal muscle mass measurement is of increasing interest in the clinical setting and the general public. The study aim was to evaluate the feasibility of developing small portable wireless contact-electrode BIA systems designed for personal body composition analysis. Three hand-held multifrequency devices were evaluated that included 4 electrode configurations (palm-to-palm [PP], 2 finger-finger configurations [FF1, FF2], palm-to-knee [PK]). Device-derived impedance values were evaluated against corresponding electrical pathways and whole-body electrical circuits measured using a gel-electrode reference BIA system [IB] (InBody, Seoul, Korea) in 311 adults (117 M, 194 F) stratified into underweight (BMI<20 kg/m2), normal-overweight (>20-30 kg/m2) and obese (>30 kg/m2) groups. Additionally, the main lean and fat-predictor variable height2/Z was examined relative to lean soft tissue mass (LST) evaluated with DXA (Prodigy, GE Lunar, Madison, WI). There were strong correlations between the 4 prototype pathways at 50 KHz and corresponding IB electrical pathways (Table; R2, 0.83-0.96, p<0.0001). Similarly, height2/Z versus DXA LST regions for the 4-prototype pathways yielded correlation coefficients that were similar to the reference InBody system. These novel BIA systems thus show promise as a means of quantifying an individual's body composition using small form factor mobile devices and to predict % fat without body weight measurement. Model I R2> Model II R2 Model III R2 P vs. IB(R to L arm) 0.96 Ht2/Z, PP vs. DXA LST arms (L+R) 0.88 Ht2/Z, IB vs. DXA LST arms (L+R) 0.95 FF1 vs. IB(R to L arm) 0.94 Ht2/Z, FF1 vs. DXA LST arms (L+R) 0.88 Ht2/Z, IB (R side) vs. DXA LST (R side) 0.92 FF2 vs. IB(R to L arm) 0.94 Ht2/Z, FF2 vs. DXA LST arms (L+R) 0.89 Ht2/Z, IB (R side) vs. DXA (total) 0.93 P-K vs. IB(R arm to R leg) 0.83 Ht2/Z, PK vs. DXA LST (R side) 0.87 Ht2/Z, PP vs. DXA LST (total) 0.90

On Small Terminal MIMO Antennas, Harmonizing Characteristic Modes With Ground Plane Geometry

multiple input–multiple output (MIMO) antenna systems are defined by fundamental figure of merits (FoM), such as branch imbalance, total efficiency, mean effective gain (MEG), and the correlation coefficient. Those FoM requirements are challenging, specially when applied to electrically small mobile devices, i.e., smart-phones, due to the form factor-reduced dimensions and multiplicity of adjacent frequency bands of operation. Uncorrelated antennas are especially important for MIMO antenna systems; other than few exceptional cases, the reduction of magnitude of complex correlation coefficient will increase the system capacity and data throughput. This work proposes an MIMO antenna system for mobile terminals, based on a realistic form factor and packaging implementation, with a very low magnitude of the complex correlation coefficient and an impressive isolation. An isolation better than 20 dB has been achieved using a folded monopole and a commonly adopted planar inverted F antenna (PIFA) on a platform with a very small form factor ( ${\bf{100}}\times {\bf{50}}\times {\bf{10}}\;\bf{mm}$ ). The proposed implementation is based on the synergy of two known techniques that consists in the: 1) reference ground plane geometry manipulation and 2) in the application of the characteristic mode theory to obtain orthogonal radiation modes. Since MIMO antenna systems at frequencies higher than 1.7 GHz are naturally proper isolated and decorreleated, this work demonstrates the proposed antenna topology enabling higher isolation and uncorrelated antenna system at 750 MHz, which is more difficult to achieve in form factors smaller than ${\bf{1}}\boldsymbol{\lambda}$ , while maintaining high total efficiency and adequate gain imbalance. In this paper, a simulation model and prototype ( ${\bf{1/4}}\boldsymbol{\lambda}$ long) measurement results are presented, demonstrating the implementation feasibility of such antenna system in realistic mobile device embodiment.

Undergraduate Ownership of Small Mobile Devices: Engagement and Use in an Academic Environment

With many students owning mobile devices and gadgets that they use for various purposes, it seems logical to investigate whether the use of these devices has the potential to facilitate seamless access to library resources. Using an online survey administered to 489 students, this study aimed to determine: the percentage of the undergraduate population primarily in science and technology disciplines who own small mobile devices; the pattern of use of mobile devices with emphasis on accessing library resources, scholarly information, or other academic content; effect of attending previous library instruction session on students’ use of mobile devices to access educational content; and variation in the pattern of ownership and use among academic and gender categories.The study found that mobile devices have become widely common, with 100 percent of the female respondents and 98 percent of the male respondents owning at least one small mobile device. Among the different academic disciplines, engineering students used their mobile devices to access library resources the most, followed by nursing, life sciences, physical sciences, and agricultural sciences.Students overwhelmingly reported using social networking apps on their mobile devices, followed by apps relating to entertainment, communication, information, education, utility, commerce, health, and religion.

Attitude of the Rudjer Boškovic Institute’s scientists to the small screen mobile devices library services

Purpose – The purpose of this paper is to get an insight in users’ opinion on library resources/services on small screen mobile devices. Objectives were to establish which types of small screen mobile devices are used and to find out is there a tendency for using academic and educational contents on such devices. Furthermore, aim was to identify whether the users need mobile friendly library web site and services at all. Also, what library resources/services and to what extent respondents consider as the important ones for mobile friendly customization. Finally the results would serve as an orientation in building mobile friendly library web site and services. The author believed that the users were still unaware of the possibility of accessing library web sites and services through mobile devices in general; therefore, this survey also had a role of raising awareness and stimulating their interest. Design/methodology/approach – The survey was focussed on small screen mobile devices with screen size up to seven inches (17.1 cm). Data collection was performed through a questionnaire containing ten questions. The questionnaire was created by LimeSurvey tool, and for mobile optimized version SurveyMonkey.com service was used too. The authors received 295 questionnaires, out of which 285 were taken into account. Findings – The survey found that the largest number of respondents own smartphone/tablet/phablet. The results show that small screen devices are, to some extent, used for educational, academic and informational purposes (reading of e-books and e-journals, education, data checking, internet searching and searching of handy information), but non-academic purposes still predominate (texting, reading e-mails, phone calls, taking pictures). Overall 64 percent of the respondents has expressed need for small screen mobile devices customized library resources/services, but there are 30 percent of undecided respondents. Croatian Scientific Bibliography, e-journals database (EZB), online databases, contact information and lecture halls reservations, has been resources/services requested by respondents to be available in a mobile friendly mode. Originality/value – The survey examines users’ opinion on a new library service before its implementation. Besides giving us a precise insight into the Rudjer Bošković Institute library users’ interest and needs for mobile friendly customization of existing library resource/service, survey gives a unique insight into the correlation of age and gender of the respondents and their answers to the question about having a small screen mobile device and opinion about the customization of library resources and services. To the author’s knowledge, this is the first users’ survey on this topic in Croatia.

Design of multiband PIFA with low SAR value for all commercial mobile communication bands

A low profile planar inverted-F antenna is proposed for mobile handset applications. Thus, our target is to introduce a new antenna that supports both services, the proposed antenna have broadband characteristic which includes all commercial service bands, GSM850/GSM900/GPS/GSM1800/GSM1900/WCDMA2100/802.11b/g/LTE2600 (824–2690 MHz) as well as 802.11a/n (5150–5825 MHz). Overall size of the antenna is 21 × 45 × 8 mm3 is well suited for mobile handsets due to its low profile, small size, wide bandwidth, the radiation patterns are satisfactorily omnidirectional across the antenna's operation bands, and good gain (the gain in some frequency bands is higher than 4 dBi). The antenna not only has a compact size, but also it supports a low specific absorption rate (SAR) radiation at all the operating frequencies. In addition, the proposed antenna is assessed using the finite difference time domain (FDTD) program written with MATLAB to validate the results. The antenna meets three challenging parameters: the compact size, the multiband operation including the low frequency bands, and the low SAR radiation. The measured results exhibit good agreement with the simulation results from CST and the FDTD program written with MATLAB. As a result, the designed antenna is suitable for small mobile devices and slim wireless applications. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:194–201, 2015.

Environment mismatch compensation using average eigenspace-based methods for robust speech recognition

The performance of speech recognition systems is adversely affected by mismatch between training and test conditions due to environmental factors. In addition to the case of test data from noisy environments, there are scenarios where the training data itself is noisy. In this study, we propose a series of methods for mismatch compensation between training and test environments, based on our "average eigenspace" approach. These methods are also shown to be effective for non-stationary mismatch conditions. An advantage is that there is no need for explicit adaptation data since the method is applied to incoming test data to find the compensatory transform. We evaluate these approaches on two separate corpora which are collected from realistic car environments: CU-Move and UTDrive. Compared with a baseline system incorporating spectral subtraction, highpass filtering and cepstral mean normalization, we obtain a relative word error rate reduction of 17---26 % by applying the proposed techniques. These methods also result in a dimensionality reduction of the feature vectors allowing for a more compact set of acoustic models in the phoneme space, a property important for automatic speech recognition for small footprint size mobile devices such as cell-phone or PDA's which require ASR in diverse environments.

IEEE 802.11 기반 저전력 위치 추적 장치의 설계 및 구현

무선 네트워크 기술과 모바일 프로세서의 성능이 향상됨에 따라 스마트 폰과 같은 무선통신이 가능한 소형 단말이 널리 활용되고 있다. 이러한 이동형 장치는 GPS를 이용하여 위치정보의 활용이 가능하여 위치정보를 기반으로 하는 서비스가 증가하고 있다. GPS는 위성신호를 수신할 수 없는 실내와 전파음영지역에서 위치 정보를 제공하지 못하며, 근거리 통신기술을 이용하는 시스템은 인프라의 구축이 필수적이다. IEEE 802.11을 기반으로 하는 추적 시스템은 널리 보급된 AP 인프라를 기반으로 위치 측정이 가능하나 표준 동작을 따를 때 심각한 전력소모의 문제가 있다. 본 논문에서는 IEEE 802.11 기반 저전력 위치 추적 장치를 제안한다. 저전력 동작을 위해 채널 검색 및 연결유지로 인한 전력소모를 최소화하여 동작시간을 극대화 하였다. 성능평가를 위해 저전력 태그 장치를 설계 및 구현하여 전력소모를 측정하였으며, 시뮬레이션 결과 기본 방법에 비해 제안 방법의 전력소모가 46% 감소함을 확인하였다. According to wireless network technology and mobile processors performance were improved, the small wireless mobile device such as smart phones has been widely utilized. The mobile devices can be used GPS information, thereby the services based on location information was increased. GPS was impossible to provide location information in indoor and signal shading environment, and the tracking systems based on short distance wireless communication are required infrastructure. The IEEE 802.11 based tracking system is possible estimation using APs, however the tracking device is exhausted battery power seriously. In this paper, we propose IEEE 802.11 based low-power tracking system. We reduced power consumption from channel scanning and network connection. For performance evaluation, we designed and implemented the tracking tag device, and measured power consumption of the device. As the simulation result, we confirmed that the power consumption was reduced 46% compare to the standard execution.

Android $$^\mathrm{TM}$$ TM development and performance analysis

The advent of emergent systems on chip and MPSocs opens a new era in the small mobile devices (Smartphones, Tablets,...) in terms of computing capabilities and applications to be addressed. Currently, these devices have multicore processors and GPUs which provide high computational power. The efficient use of such devices, including the parallel power, is still a challenge for general-purpose programmers. In the last years Android has become the dominant platform in the small mobile devices. In addition, it has a large community of developers. For application development, Android provides two development kits, the Software Development Kit and Native Development Kit. To exploit the high computational capabilities on current devices, Android provides Renderscript, an API that allows the execution of parallel applications and it is designed to be used in applications that require high computing power. The development model used involves an important impact in the performance of the applications. In this paper, we address the evaluation of the performance on Android platforms. A set of benchmark applications has been implemented to evaluate the performance of the different development models. Sequential and parallel versions of the different development kits are considered in the computational experience. This benchmark and the computational experience achieved are greatly helpful to the programmer for understanding sources of overhead and bottlenecks in the developed code.

Lightweight Word Spacing Model Based on Short Text Messages for Social Networking in Smart Homes

In smart homes, information appliances interact with residents via social network services. To capture residents' intentions, the information appliances should analyze short text messages entered typically through small mobile devices. However, most information appliances have hardware constraints such as small memory, limited battery capacity, and restricted processing power. Therefore, it is not easy to embed intelligent applications based on natural language processing (NLP) techniques, which traditionally require large memory and high-end processing power, into information appliances. To overcome this problem, lightweight NLP modules should be implemented. We propose an automatic word spacing system, the first step module of NLP for many languages with their own word spacing rules, which is designed for information appliances with limited hardware resources. The proposed system consists of a word spacing dictionary and a pattern-matching module. When a sentence is entered, the pattern-matching module inserts spaces by simply looking up the word spacing dictionary in a back-off manner. In comparative experiments with previous models, the proposed method showed low memory usage (0.79 MB) and high character-unit accuracy (0.9460) without requiring complex arithmetical computations. On the basis of these experiments, we conclude that the proposed system is suitable for information appliances with many hardware limitations.

The 36th Year to Come

The 36th Year to Come

Real time exploration and management of large medical volumetric datasets on small mobile devices—Evaluation of remote volume rendering approach

In this paper I present the architecture of system that can be used for real time exploration and management of large medical volumetric datasets. The new state of the art solution presented in this paper is an example of visual data management system. System prototype evaluation proved that it is possible to use low-powered (and cheap) up-to-date mobile devices with programmable GPUs as the remote interfaces for exploration of large volumetric medical data. The implementation was done with high-level programming language that enables portability between different hardware models. The lack of lossy compression enables to display high quality medical images visualizations without any simplifications and noises in frequency domain. The prototype of system is capable to remotely render and send to a client (for example cell phone or tablet) rendered data with frequency 30fps with limited resolution during interaction. One second after the interaction is finished client machine receives full resolution image. The evaluation of the system was performed on volumetric computed tomography angiography image with approximate size 5123voxels.

Atomic layer deposition of functional films for Li‐ion microbatteries

The lithium ion battery concept is a promising energy storage system, both for larger automotive systems and smaller mobile devices. The smallest of these, the microbatteries, are commonly based on the all‐solid state concept consisting of thin layers of electroactive materials separated by a solid state electrolyte. The fact that solid state electrolytes are required puts rather severe constraints on the materials in terms of electronic and ionic conductivity, as well as lack of pinholes otherwise leading to self‐discharge. The atomic layer deposition (ALD) technology is especially suitable for realization of such microbatteries for the Li‐ion technology. ALD has an inherent nature to deposit conformal and pinhole free layers on complex geometrical shapes, an architecture most commonly adopted for microbattery designs. The current paper gives an overview of ALD‐type deposition processes of functional battery materials, including cathodes, electrolytes, and anodes with the aim of developing all‐solid‐state batteries. Deposition of Li‐containing materials by the ALD technique appears challenging and the status of current efforts is discussed.

Behavioral Screening Measures Delivered With a Smartphone App

The smartphone is an increasingly widespread technological vehicle for general health and psychological health promotion, evaluation, education, and sometimes intervention. However, the psychometric performance of behavioral health screening measures has not been commonly evaluated for the new, small-format, touch-screen medium. Before mobile-based applications for behavioral health screening can be disseminated confidently, the reliability and the validity of measures administered by the smartphone must be evaluated. We compared psychometric properties (i.e., internal consistency and test-retest reliability) of seven behavioral health measures completed on paper, a computer, and an iPhone by 45 army soldiers. The results showed the internal consistencies of the smartphone-delivered measures to be equivalent and very high across all three modalities and the test-retest reliability of the iPhone measures also to be very high. Furthermore, completion of the behavioral screening measures by the iPhone was highly preferred over the other modalities and was reported to be easy and convenient. Our findings help corroborate the use of smartphones and other small mobile devices for behavioral health screening.

Navigation of Mobile Devices based on Embedded Image Processing with Support of GPS Systems and Sensors

A recent development in system-on-chip processors provides possibilities of integration performancedemanding tasks, which can be performed only with the help of superior range of computers before. The article introduces advanced control system with embedded image processing to improving GPS localization of autonomous mobile devices in real environment. The main control system is based on ARM (SoC.) architecture integrated in Raspberry PI development board. Presented control systems can handle real-time video capturing, power-efficient image processing operation for example (thresholding, binarization, motion detection, ...etc.) and streaming results images as video. GPS precision can provide only 3 meters precision together with WAAS (Egnos) satellite. Our solution uses GPS solution and embedded image processing to detect border of roads or sidewalks. Our algorithm detects road or sidewalk universally without detection of white line in roadside, because pathways and some roads cannot provide this feature. Control system can be used for small autonomous mobile devices for example parts transport in industrial park of heavy industries, where are long distances between production halls.

Web Content Authoring for Ubiquitous and Context Aware Learning - A Tag based Approach

Web pages are mostly designed keeping the desktop PCs in mind. Displaying huge web content into the small screen mobile devices helps the user in no way. Mobile learners, who need to learn across context with mobile devices, need only the essentials and very less explanation on the subject matter. To achieve this, the present workers propose a Mobile Tag Library to be used by web authors with other HTML tags to develop dual purpose web pages and also a mobile browser capable of selective retrieval of the corresponding portion of web content and display that in a small-screen device.

Design an AR Application in Finding Preferred Dining Place With Social Network Capability (ARAFEPS)

Location Based Service (LBS) application help people in finding places or point of interest. However, spatial information in LBS is presented as a map in a small mobile device screen which makes the user difficult to understand and to find the location they need. It is possible that user might have disorientation in finding the place although they are presented with correct map. ARAFEPs (Augmented Reality Assistant to Finding Preferred Dining Place) is an Augmented Reality application to support its user to find the nearest and preferred dining place such as restaurant, fast food and food court. It is developed using Layar AR as platform. It presents the user with spatial information in a way that user could aware and understand the places surround them. Additional and relevant information that are presented in AR aids users to decide which dining place fits the needs of the user.

Live mobile collaboration for video production: design, guidelines, and requirements

Traditional cameras and video equipment are gradually losing the race with smart phones and small mobile devices that allow video, photo, and audio capturing on the go. Users are now quickly creating movies and taking photos whenever and wherever they go, particularly at concerts and live events (e.g., shows, sport events). Still, in-situ media capturing with such devices poses constraints to any user, especially amateur ones. In this paper, we present the design and evaluation of a mobile video capture suite that allows for cooperative ad hoc production. Our system relies on ad hoc in-situ collaboration offering users the ability to switch between streams and cooperate with each other in order to capture better media with mobile devices. Our main contribution is the real-time awareness that users gain on media capturing endeavors around them and the possibility to collect that data for personal use once the event is over. This contribution is further emphasized by the geo-referenced cues that support the overall user interface and the management of the different media streams. As a secondary contribution, we report on lessons and design guidelines that emerged and apply to in-situ design of rich video collaborative experiences and with the elicitation of functional and usability requirements related to privacy, social connections, and gamification.