Efficient profile aggregation and policy evaluation in a middleware for adaptive mobile applications

There is a large consensus on the need for a middleware to efficiently support adaptation in pervasive and mobile computing. Advanced forms of adaptation require the aggregation of context data and the evaluation of policy rules that are typically provided by multiple sources. This paper addresses the problem of designing the reasoning core of a middleware that supports these tasks, while guaranteeing very low response times as required by mobile applications. Technically, the paper presents strategies to deal with conflicting rules, algorithms that implement the strategies, and algorithms that detect and solve potential rule cycles. A detailed experimental analysis supports the theoretical results and shows the applicability of the resulting middleware in large-scale applications.     

A unified methodology for the evaluation of accessibility and usability of mobile applications

This article reports a unified methodology developed to evaluate the accessibility and usability of mobile computing applications, which is intended to guarantee universal access as far as possible. As a basis for the methodology, this paper presents an analysis of the accessibility guidelines, conducted to take into account the specificity of mobile systems, as well as a set of usability heuristics, specifically devised for mobile computing. Finally, it presents the results of the application of the proposed methodology to applications that have been semi-automatically developed by the MAIS Designer, a new design tool that provides applications suited to different mobile devices.     

Gossip-based cooperative caching for mobile applications in mobile wireless networks

Cooperative caching is an efficient way to improve the performance of data access in mobile wireless networks, by cache nodes selecting different data items in their limited storage in order to reduce total access delay. With more demands on sharing a video or other data, especially for mobile applications in an Internet-based Mobile Ad Hoc Network, considering the relations among data items in cooperative caching becomes more important than before. However, most of the existing works do not consider these inherent relations among data items, such as the logical, temporal, or spatial relations. In this paper, we present a novel solution, Gossip-based Cooperative Caching (GosCC) to address the cache placement problem, and consider the sequential relation among data items. Each mobile node stores the IDs of data items cached locally and the ID of the data item in use into its progress report. Each mobile node also makes use of these progress reports to determine whether a data item should be cached locally. These progress reports are propagated within the network in a gossip-based way. To improve the user experience, GosCC aims to provide users with an uninterrupted data access service. Simulation results show that GosCC achieves better performance than Benefit-based Data Caching and HybridCache, in terms of average interruption intervals and average interruption times, while sacrificing message cost to a certain degree.     

Optimal deployment of mobile cloudlets for mobile applications in edge computing

The Journal of Supercomputing - In the evolution of Internet of Things and 5G networks, edge computing, as an emerging computing paradigm, can effectively reduce the latency of accessing the cloud...     

基于BP网神经网络的铁矿取样品位波动的校核

按照ISO3084对铁矿石进行品位波动校核是一种常规方法,但该方法需要耗费大量的人力和财力,检验校核相当不经济。本文利用BP神经网络,采用第四代程序语言MATLAB,利用历年来积累的检验数据或在线粒度检测的部分数据作为学习训练样本,建立数学模型,同时通过MATLAB的命令行方式、GUI方式和系统仿真对铁矿石的品位波动进行模拟检验,模拟结果误差小,得到的网络能为相关铁矿石品位波动情况获取提供手段,最终为铁矿石取制样提供品位波动校核依据。     

The daily work load of refuse collectors working with three different collecting methods: a field study

The daily work load of 116 Dutch (male) refuse collectors working with polythene bags, two-wheeled mini-containers and large four-wheeled containers was studied. To this end a time analysis of the tasks and activities in the real working situation was made and the postures and the physiological work load of the collector working with the three different methods was assessed. Manual materials handling and the corresponding working postures were studied by means of observations. Heart rate (HR) was continuously recorded during the working day. Furthermore, to enable the assessment of the work load during refuse collecting as a percentage of the maximal oxygen uptake ([Vdot]O₂max) every refuse collectors' relationship between HR and oxygen uptake was measured during a simulation of the tasks and activities in the laboratory. The range in total working time of the refuse collectors was large. Most time is spent on the task ‘loading’; this lasted on average about 5?h. The mean number of handled objects for the three refuse collecting methods is 1500 bags, 500 mini-containers and 120 large containers respectively. The mean amount of collected refuse per collector of bags and mini-containers is about 11000kg. For the collectors of the large containers it is 27% higher, namely about 14000kg. The mean weight of one object for the bags, mini-container and large container is 7, 22 and 110?kg respectively. The straight posture was the most common in refuse collecting by bags. The posture flexed at the trunk and bent forwards or backwards occurred often while pushing and pulling containers. However, the refuse collectors of the large containers pushed and pulled for shorter periods during a working day in comparison with collectors of the mini-containers. Criteria for energetic overload were set at a mean energy expendiiure of 30% [Vdot]O₂ max and an energy expenditure of 50% [Vdot]O₂ max or more for a maximum of 60?min per day. According to these limits the energetic work load of the collectors of bags was indicated as being too high. In order to formulate guidelines in terms of mechanical and energetic load it is necessary to measure more accurately these loads during refuse collecting activities.     

Comparative evaluation of range sensor accuracy for indoor mobile robotics and automated logistics applications

3D range sensing is an important topic in robotics, as it is a component in vital autonomous subsystems such as for collision avoidance, mapping and perception. The development of affordable, high frame rate and precise 3D range sensors is thus of considerable interest. Recent advances in sensing technology have produced several novel sensors that attempt to meet these requirements. This work is concerned with the development of a holistic method for accuracy evaluation of the measurements produced by such devices. A method for comparison of range sensor output to a set of reference distance measurements, without using a precise ground truth environment model, is proposed. This article presents an extensive evaluation of three novel depth sensors — the Swiss Ranger SR-4000, Fotonic B70 and Microsoft Kinect. Tests are concentrated on the automated logistics scenario of container unloading. Six different setups of box-, cylinder-, and sack-shaped goods inside a mock-up container are used to collect range measurements. Comparisons are performed against hand-crafted ground truth data, as well as against a reference actuated Laser Range Finder (aLRF) system. Additional test cases in an uncontrolled indoor environment are performed in order to evaluate the sensors’ performance in a challenging, realistic application scenario.     

Guidelines for energetic load in three methods of refuse collecting

The energetic load and guidelines were formulated for energetic load in three methods of refuse collecting. These methods were collecting refuse in polythene bags (in a city area and in a suburb), in two-wheeled mini-containers and in large four-wheeled containers. To determine the energetic load of the collecting methods, these collecting methods were simulated in the laboratory. The simulation protocols were based on data such as weight of the handled materials, and the frequency and duration of the most prominent refuse collecting activities as found in the preliminary field study. During the execution of the protocols the heart rate and oxygen uptake were continuously recorded. The maximal oxygen uptake was determined during a continuous running protocol on a treadmill. The energetic load was expressed in terms of percentage of the maximal oxygen uptake. As the limit for the energetic load a value of 30% of the maximal oxygen uptake during an 8-h working day was chosen. The limit for energetic overload was exceeded for the maximal oxygen uptake for refuse collecting with polythene bags in a city area (44·5%), collecting with bags in a suburb (37·2%) and with mini-containers. The percentage of the maximal oxygen uptake for collecting with large containers was 28·4%, which was below the limit for the energetic load of 30%. Guidelines were formulated for the relevant occupational field terms: maximal amount of collecting hours and maximal amount of collected refuse per collector per hour. The guidelines were formulated in percentiles (P₉₀ and P₇₅). This means that 90 and 75% of the refuse collecting population in The Netherlands will be prevented from having an energetic overload above the limit of 30% of the maximal oxygen uptake.     

Perses: A framework for the continuous evaluation of the QoS of distributed mobile applications

The increasing capabilities of mobile devices have led to the emergence of new paradigms exploiting them. These paradigms foster the onload and distribution of functionalities on mobile devices, allowing the development of distributed mobile applications. This distribution reduces the latency and the data traffic overhead and improves privacy. As in any other mobile application, their success largely depends on the quality of service (QoS) they offer. Nevertheless, the evaluation of distributed mobile applications is particularly complex due to the number, heterogeneity, and interactions between the devices involved. Current techniques allow developers to assess the quality of a single device, but they are not designed for highly heterogeneous, distributed, and collaborative environments. This paper presents a framework called Perses, which allows the creation of virtual scenarios with multiple heterogeneous mobile devices to launch end-to-end tests to evaluate not only each device but also the interactions among them. The framework was evaluated against a real deployment, showing that the behavior and the quality attributes measured are similar to those of the real deployment, allowing developers to evaluate these applications before launching them. Finally, Perses was integrated into a DevOps methodology to automate its execution and further facilitate its adoption by software companies.     

Elastic resource provisioning in hybrid mobile cloud for computationally intensive mobile applications

The paper addresses the integration of hybrid cloud with mobile applications. The challenge about hybrid mobile cloud resource provisioning is the trade-offs between energy consumption, performance provided to users and how resources, such as processing power and network, are being utilized. The proposed elastic hybrid mobile cloud resource provisioning model is jointly optimized to improve mobile user experience within the constraints of available resources and user QoS requirement. The paper presents the system utility of hybrid cloud system involving local cloud and public cloud infrastructure. From the perspectives of both mobile applications and cloud providers, the proposed system utility is optimized to improve the performance of mobile applications and the utilization of cloud resources. The proposed elastic hybrid mobile cloud resource provisioning algorithm includes two sub-algorithms. To evaluate and validate performance of the proposed algorithm, a series of experiments are conducted. The comparison results and analyses are discussed. The experimental results show the improvement to previous works.     

移动位置服务的应用发展研究

移动位置服务是移动运营商和服务提供商联合推出的基于地理位置信息服务,用户通过移动终端获取位置信息及产品服务。中国的移动位置服务开展较早,但相比于美国等发达国家,并没有获得用户的广泛接受。本文通过研究移动位置服务的发展现状和用户行为,提出发展对策。     

Text/shape classifier for mobile applications with handwriting input

The paper provides a practical solution to a real-time text/shape differentiation problem for online handwriting input. The proposed structure of the classification system comprises stroke grouping and stroke classification blocks. A new set of features is derived that has low computational complexity. The method achieves 98.5 % text/shape classification accuracy on a benchmark dataset. The proposed stroke grouping machine learning approach improves classification robustness in relation to different input styles. In contrast to the threshold-based techniques, this grouping adaptation enhances the overall discriminating accuracy of the text/shape recognition system by 11.3 %. The solution improves system’s response on a touch-screen device.     

Classification of reflectors with an ultrasonic sensor for mobile robot applications

This paper describes a sensor model made up of four ultrasonic transducers able to classify reflectors (wall, edge or corner) in specular environments. The main goal has been to effect the classification from a single reading cycle: emission of ultrasounds and reception of echoes (measuring only times of flight—TOFs). Working from the four TOFs obtained after a single emission of ultrasounds (thereby facilitating its practical implementation in a mobile robot, when readings are taken while the robot is moving), an algorithm has been proposed for discriminating between edge and plane type reflectors. The configuration of the four transducers enabled dependent discriminating functions to be determined directly from the quadratic terms of the TOFs, without the need for previous geometric transformations. Special attention was given to the effect of the separation between the sensor transducers and the reading-associated noise. Finally, some considerations have been pointed out about the possibility of two transducers emitting, so allowing discrimination between walls and corners.     

教师教学情绪综合评价分析

教师教学情绪对课堂教学效果和学生的学习状态有重大的影响.基于自然语言处理理论,建立了分析教师教学情绪的情感倾向指标、情感波动指标和敏感词指标.为了对比不同教师之间的总体教学情绪,采用离差权评价模型建立了教师情绪综合评价方法.实验表明,上述指标和综合评价方法能有效体现教师课堂教学情绪和他们的情绪差异.本研究成果为智能分析...     

Precise execution offloading for applications with dynamic behavior in mobile cloud computing

In order to accommodate the high demand for performance in smartphones, mobile cloud computing techniques, which aim to enhance a smartphone’s performance through utilizing powerful cloud servers, were suggested. Among such techniques, execution offloading, which migrates a thread between a mobile device and a server, is often employed. In such execution offloading techniques, it is typical to dynamically decide what code part is to be offloaded through decision making algorithms. In order to achieve optimal offloading performance, however, the gain and cost of offloading must be predicted accurately for such algorithms. Previous works did not try hard to do this because it is usually expensive to make an accurate prediction. Thus in this paper, we introduce novel techniques to automatically generate accurate and efficient method-wise performance predictors for mobile applications and empirically show they enhance the performance of offloading.     

Usability evaluation methods for mobile serious games applied to health: a systematic review

Universal Access in the Information Society - This paper aims to present the results of a systematic review focused on usability evaluation methods for serious games (SG) of mobile devices...     

Investigation on runtime partitioning of elastic mobile applications for mobile cloud computing

The latest developments in mobile computing technology have increased the computing capabilities of smartphones in terms of storage capacity, features support such as multimodal connectivity, and support for customized user applications. Mobile devices are, however, still intrinsically limited by low bandwidth, computing power, and battery lifetime. Therefore, the computing power of computational clouds is tapped on demand basis for mitigating resources limitations in mobile devices. Mobile cloud computing (MCC) is believed to be able to leverage cloud application processing services for alleviating the computing limitations of smartphones. In MCC, application offloading is implemented as a significant software level solution for sharing the application processing load of smartphones. The challenging aspect of application offloading frameworks is the resources intensive mechanism of runtime profiling and partitioning of elastic mobile applications, which involves additional computing resources utilization on Smart Mobile Devices (SMDs). This paper investigates the overhead of runtime application partitioning on SMD by analyzing additional resources utilization on SMD in the mechanism of runtime application profiling and partitioning. We evaluate the mechanism of runtime application partitioning on SMDs in the SmartSim simulation environment and validate the overhead of runtime application profiling by running prototype application in the real mobile computing environment. Empirical results indicate that additional computing resources are utilized in runtime application profiling and partitioning. Hence, lightweight alternatives with optimal distributed deployment and management mechanism are mandatory for accessing application processing services of computational clouds.     

Experimental validation and field performance metrics of a hybrid mobile robot mechanism

This paper presents the experimental validation and field testing of a novel hybrid mobile robot (HMR) system using a complete physical prototype. The mobile robot system consists of a hybrid mechanism whereby the locomotion platform and manipulator arm are designed as one entity to support both locomotion and manipulation symbiotically and interchangeably. The mechanical design is briefly described along with the related control hardware architecture based on an embedded onboard wireless communication network between the robot's subsystems, including distributed onboard power using Li‐ion batteries. The paper focuses on demonstrating through extensive experimental results the qualitative and quantitative field performance improvements of the mechanical design and how it significantly enhances mobile robot functionality in terms of the new operative locomotion and manipulation capabilities that it provides. In terms of traversing challenging obstacles, the robot was able to surmount cylindrical obstacles up to 0.6‐m diameter; cross ditches with at least 0.635‐m width; climb and descend step obstacles up to 0.7‐m height; and climb and descend stairs of different materials (wood, metal, concrete, plastic plaster, etc.), different stair riser and run sizes, and inclinations up to 60 deg. The robot also demonstrated the ability to manipulate objects up to 61 kg before and after flipping over, including pushing capacity of up to 61 kg when lifting objects from underneath. The above‐mentioned functions are critical in various challenging applications, such as search and rescue missions, military and police operations, and hazardous site inspections. © 2010 Wiley Periodicals, Inc.