边缘环境下计算密集型任务调度研究综述

随着移动设备数量的急剧增长及计算密集型应用如人脸识别、车联网以及虚拟现实等的广泛使用,为了实现满足用户QoS请求的任务和协同资源的最优匹配,使用合理的计算密集型应用的任务调度方案,从而解决边缘云中心时延长、成本高、负载不均衡和资源利用率低等问题。阐述了边缘计算环境下计算密集型应用的任务调度框架、执行过程、应用场景及性能指标。从时间和成本、能耗和资源利用率以及负载均衡和吞吐量为优化目标的边缘计算环境下计算密集型应用的任务调度策略进行了对比和分析,并归纳出目前这些策略的优缺点及适用场景。通过分析5G环境下基于SDN的边缘计算架构,提出了基于SDN环境下的边缘计算密集型数据包任务调度策略、基于深度强化学习的计算密集型应用的任务调度策略和5G IoV网络中多目标跨层任务调度策略。从容错调度、动态微服务调度、人群感知调度以及安全和隐私等几个方面总结和归纳了目前边缘计算环境中任务调度所面临的挑战。     

Automatic adaptation of mobile applications to different user devices using modular mobile agents

Wearable, handheld, and embedded or standalone intelligent devices are becoming quite common and can support a diverse range of applications. In order to simplify development of applications which can adapt to a variety of mobile devices, we propose an adaptation framework which includes three techniques: follow‐me, context‐aware adaptation, and remote control scheme. For the first, we construct a personal agent capable of carrying its owner's applications. Second, we design a personal agent capable of carrying applications with an adaptable hierarchical structure. Then, applications can be adapted approximately to the context of evices by using an attribute‐based component decision algorithm. Finally, to achieve a remote control scheme, we distribute the computational load of applications on the resource‐restricted mobile devices. An application is divided into two parts that can be executed on a user device and a server separately. In short, this framework facilitates the development of widespread applications for ubiquitous computing environments. Furthermore, it enables the applications to follow their owners and automatically adapt to different devices. Copyright © 2005 John Wiley & Sons, Ltd.     

Adapting groupware systems to changes in the collaborator’s context of use

Owing to the dynamic nature of collaborative environments, the software intended to support collaborative work should adapt itself to the different situations that may occur. This requirement is related to the concept of “context of use”, which has been considered as an important aspect in the design of interactive systems. Nevertheless, two main problems about this concept have been identified by current research in context-aware computing: (1) most of the studies have mainly focused on the context of a single user, so the context of multiple users involved in a common endeavor remains little explored, and (2) adaptability in context-aware systems generally takes into account a reduced number of contextual variables (mainly the user’s location and platform). In this paper, we firstly re-conceptualize the notion of “context of use”, in order to consider the main characteristics of collaborative environments. Based on this new notion, we then design and implement a framework that allows application developers to specify the adaptability of groupware systems in terms of the state of activities, roles, collaborators’ location, available resources, and other typical variables of working groups. This framework has been generalized from scenarios that highlight dynamic situations presented in real collaborative settings. Finally, we validate our proposal by a set of applications that are able to adapt their user interface and functionality, when significant changes are produced in the environment, the working group, and/or the used devices.     

An application framework for developing collaborative handheld decision-making tools

This paper describes an application framework supporting collaborative handheld decision-making (CHDM). The main characteristics of the framework are: (1) extensive usage of visual elements and gestures; and (2) independence from specific decision-making methods, processes and tasks. The research departed from the analysis and systematisation of several CHDM scenarios, highlighting repeatable behaviour across multiple decision-making contexts. From these scenarios, we distilled a coherent set of common functional requirements organised in three main categories: process, macro- and micro-functionality. The proposed framework has been validated at length through the development of several CHDM tools. Six different tools are described in the paper. The main contribution of this work is a common foundation for developing CHDM tools.     

Mobile PointMe-based spatial haptic interaction with annotated media for learning purposes

In this paper, we propose a framework to facilitate handheld device-based PointMe interaction with annotated media content, where the user points his/her handheld device to the media presentation screen in order to access services/information from the annotated media. Each annotation is encoded into customized learning object metadata (LOM) format that provides access point for available information about a specific media on the screen. By incorporating a fusion of infra-red (IR) motion points and accelerometer data of the handheld device, the system determines the learner’s PointMe location on the media screen. By using the pointed location spatial geometrical query is performed over the displayed annotated media in order to deliver learner’s level-specific interactive learning content to the user’s handheld device. The level customization is achieved by incorporating learner’s age, progress, etc., parameters in the media content delivery process. We design intuitive learning scenarios by leveraging the PointMe interaction scheme, where learners are challenged to answer quiz questions in learning-based games. This real-world interaction technique with the annotated media and seamless virtual learning information acquisition process makes the system transparent to young learners and encourage them to engage and concentrate on their learning activities. We develop a prototype and perform experiments in a technology-augmented learning space to show the suitability of the proposed approach.     

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.     

A hybrid positioning system for technology‐independent location‐aware computing

Location‐aware computing is a form of context‐aware mobile computing that refers to the ability of providing users with services that depend on their position. Locating the user terminal, often called positioning, is essential in this form of computing. Towards this aim, several technologies exist, ranging from personal area networking, to indoor, outdoor, and up to geographic area systems. Developers of location‐aware software applications have to face with a number of design choices, that typically depend on the chosen technology. This work addresses the problem of easing the development of pull location‐aware applications, by allowing uniform access to multiple heterogeneous positioning systems. Towards this aim, the paper proposes an approach to structure location‐aware mobile computing systems in a way independent of positioning technologies. The approach consists in structuring the system into a layered architecture, that provides application developers with a standard Java Application Programming Interface (JSR‐179 API), and encapsulates location data management and technology‐specific positioning subsystems into lower layers with clear interfaces. In order to demonstrate the proposed approach we present the development of HyLocSys. It is an open hybrid software architecture designed to support indoor/outdoor applications, which allows the uniform (combined or separate) use of several positioning technologies. HyLocSys uses a hybrid data model, which allows the integration of different location information representations (using symbolic and geometric coordinates). Moreover, it allows support to handset‐ and infrastructure‐based positioning approaches while respecting the privacy of the user. The paper presents a prototypal implementation of HyLocSys for heterogeneous scenarios. It has been implemented and tested on several platforms and mobile devices. Copyright © 2009 John Wiley & Sons, Ltd.     

Lessons learned: Evaluating visualizations for occluded objects in handheld augmented reality

Handheld devices like smartphones and tablets have emerged as one of the most promising platforms for Augmented Reality (AR). The increased usage of these portable handheld devices has enabled handheld AR applications to reach the end-users; hence, it is timely and important to seriously consider the user experience of such applications. AR visualizations for occluded objects enable an observer to look through objects. AR visualizations have been predominantly evaluated using Head-Worn Displays (HWDs), handheld devices have rarely been used. However, unless we gain a better understanding of the perceptual and cognitive effects of handheld AR systems, effective interfaces for handheld devices cannot be designed. Similarly, human perception of AR systems in outdoor environments, which provide a higher degree of variation than indoor environments, has only been insufficiently explored.In this paper, we present insights acquired from five experiments we performed using handheld devices in outdoor locations. We provide design recommendations for handheld AR systems equipped with visualizations for occluded objects. Our key conclusions are the following: (1) Use of visualizations for occluded objects improves the depth perception of occluded objects akin to non-occluded objects. (2) To support different scenarios, handheld AR systems should provide multiple visualizations for occluded objects to complement each other. (3) Visual clutter in AR visualizations reduces the visibility of occluded objects and deteriorates depth judgment; depth judgment can be improved by providing clear visibility of the occluded objects. (4) Similar to virtual reality interfaces, both egocentric and exocentric distances are underestimated in handheld AR. (5) Depth perception will improve if handheld AR systems can dynamically adapt their geometric field of view (GFOV) to match the display field of view (DFOV). (6) Large handheld displays are hard to carry and use; however, they enable users to better grasp the depth of multiple graphical objects that are presented simultaneously.     

Mobile learning: A framework and evaluation

Wireless data communications in form of Short Message Service (SMS) and Wireless Access Protocols (WAP) browsers have gained global popularity, yet, not much has been done to extend the usage of these devices in electronic learning (e-learning). This project explores the extension of e-learning into wireless/handheld (W/H) computing devices with the help of a mobile learning (m-learning) framework. This framework provides the requirements to develop m-learning applications that can be used to complement classroom or distance learning. A prototype application was developed to link W/H devices to three course websites. The m-learning applications were pilot-tested for two semesters with a total of 63 students from undergraduate and graduate courses at our university. The students used the m-learning environment with a variety of W/H devices and reported their experiences through a survey and interviews at the end of the semester. The results from this exploratory study provide a better understanding on the role of mobile technology in higher education.     

Informal learning with PDAs and smartphones

Abstract There has been increasing interest in informal learning in recent years alongside interest in how such learning can be supported by technology. However, relatively little is known about the extent to which adults make use of their own mobile devices to support informal learning. In this study, a survey was used to investigate whether, and to what extent, experienced users of mobile devices use their mobile devices to support intentional informal learning. If so, do they make use of mobile device connectivity to support opportunistic informal learning and does such connectivity support or encourage collaborative informal learning? Experienced mobile device users were recruited from web forums and business, and asked whether they used their devices to support informal learning. A pattern of learning uses emerged, some of which deployed the mobile device capabilities relatively unchanged, others triggered adaptations to typical learning activities to provide a better fit to the needs of the learner. These informal learning activities provided the basis for the design of a flexible mobile learning framework that can be extended to support developments in mobile technology, and increasing use of Web 2.0 technologies by informal learners.     

The foundations of a theory-aware authoring tool for CSCL design

One of the most useful ways to enhance collaboration is to create scenarios where learners are able to interact more effectively. Nevertheless, the design of pedagogically sound and well-thought-out collaborative learning scenarios is a complex issue. This is due to the context of group learning where the synergy among learners’ interactions affects learning processes and, hence, the learning outcome. Although many advances have been made to support the designing of collaborative learning scenarios through technology, a more systematic approach is lacking. With the limitations of the current designing methods and tools, it is difficult to develop intelligent authoring systems that can guide users in order to produce more effective collaboration. One of the main difficulties with creating a more consistent (computer-understandable) approach to designing collaboration is the necessity of proposing better ways to formalize the group learning processes. In this paper, we present an innovative approach that uses ontologies and concepts from learning theories to create a framework that represents collaborative learning and its processes. Ontologies provide the necessary formalization to represent collaboration, while learning theories provide the concepts to justify and support the development of effective learning scenarios. Such an approach contributes to establish the foundations for the development of the next generation of intelligent authoring systems referred to as theory-aware systems. To verify the viability and usefulness of our proposed ontological framework in the context of systematic design, the development and use of an intelligent authoring tool for CSCL design is presented. This system is able to reason on ontologies to give suggestions that help users to create theory-compliant collaborative learning scenarios. We carried out several experiments with teachers in a geometry drawing course and the results indicate that the system helps teachers to create and interchange their scenarios more easily and facilitates the selection of important pedagogical strategies that influence positively the designing and effectiveness of group activities.     

On the Design and Prototype Implementation of a Multimodal Situation Aware System

In this paper we describe the design concepts and prototype implementation of a situation aware ubiquitous computing system using multiple modalities such as National Marine Electronics Association (NMEA) data from global positioning system (GPS) receivers, text, speech, environmental audio, and handwriting inputs. While most mobile and communication devices know where and who they are, by accessing context information primarily in the form of location, time stamps, and user identity, the concept of sharing of this information in a reliable and intelligent fashion is crucial in many scenarios. A framework which takes the concept of context aware computing to the level of situation aware computing by intelligent information exchange between context aware devices is designed and implemented in this work. Four sensual modes of contextual information like text, speech, environmental audio, and handwriting are augmented to conventional contextual information sources like location from GPS, user identity based on IP addresses (IPA), and time stamps. Each device derives its context not necessarily using the same criteria or parameters but by employing selective fusion and fission of multiple modalities. The processing of each individual modality takes place at the client device followed by the summarization of context as a text file. Exchange of dynamic context information between devices is enabled in real time to create multimodal situation aware devices. A central repository of all user context profiles is also created to enable self-learning devices in the future. Based on the results of simulated situations and real field deployments it is shown that the use of multiple modalities like speech, environmental audio, and handwriting inputs along with conventional modalities can create devices with enhanced situational awareness.      

Data Collection in the Palm of Your Hand: A Case Study

Portable computing is an emerging technology that allows computing to occur practically anywhere. Going beyond the typical use as the "pocket-sized organizer," new methods of using handheld devices are being developed. One new method is to use handheld devices to collect data in the field. The portability of handheld devices allows for data collection in virtually any setting and frees the researcher from the confines of the laboratory. This article describes the process of converting a paper-and-pencil method of data collection to a 3Com Palm Pilot(tm)III application. An iterative design process was used to evaluate the ease of use of the new application. The new application (a) substantially reduced time to transfer the data to a database, (b) did not interfere with the task, (c) allowed the user to accomplish the same tasks as with the paper method while adding functionality beyond the paper method, and (d) was rated as easy to use.     

Design, implementation and validation of a Europe-wide pedagogical framework for e-Learning

Within the context of a Europe-wide project UNITE, a number of European partners set out to design, implement and validate a pedagogical framework (PF) for e- and m-Learning in secondary schools. The process of formulating and testing the PF was an evolutionary one that reflected the experiences and skills of the various European partners and secondary schools involved in the project. The framework involved pedagogies which underpin the teaching of subject matter in a number of European secondary schools as well as the ways in which learning is delivered and assessed. The PF represents an essential part of the e-Learning system conceptualization and development and offers sound concepts for the development of learning scenarios in order to enhance the learning experience of students in secondary schools. A five-component framework which, by means of its constituents, drives and guides the creation of e-Learning scenarios was designed and tested. It is composed of the pedagogical framework context, pedagogical approaches, assessment techniques, teacher education and national specifics and current pedagogical practices implemented in national curricula. A series of learning scenarios were created to test the PF in classrooms. A detailed exemplar of a scenario in practice is offered. An evaluation of the scenarios based on [Reeves, T. C., 1994. Evaluating what really matters in computer-based education. In M. Wild, D. Kirkpatrick (Eds.), Computer education: new perspectives (pp. 219–246). Perth, Australia: MASTEC] pedagogical dimensions revealed that UNITE is based on constructivist and cognitive foundations. With increased experience of the system the teachers’ implementation of the pedagogical framework developed into increased mastery in the school context. Teachers from the second validation phase became more confident in their application of the framework principles and evaluated more positively the outcomes. This helped them to become more aware of the opportunities offered by the framework in their secondary school teaching. In order to bring this about the supports for change were put into place at the levels of pedagogical design, administrative support and the provision of the required resources and appropriate continuing professional development. The project has sought to create this support structure to ensure maximal benefits of the system for teaching and learning. Such a pedagogical support PF has offered scope for both collaborative and autonomous learning which have brought about value-added teaching and learning effects in the Europe-wide network of schools.     

Real-time collaboration through web applications: an introduction to the Toolkit for Web-based Interactive Collaborative Environments (TWICE)

The widespread availability of personal mobile devices, combined with the increasing availability of stationary public devices such as large interactive displays, creates new opportunities for computer-supported collaborative work. In particular, these two factors enable the emergence of collaborative scenarios, whether planned or spontaneous, in any location, and previous obstacles to such collaborative settings such as limitations on the number of devices available for use and infrastructure costs can be overcome more easily. As hardware restrictions diminish, the need for software toolkits that simplify the development of distributed collaborative applications allowing for device heterogeneity, true multi-user interaction and spontaneous emergence increases. In this article, we describe the Toolkit for Web-based Interactive Collaborative Environments whose aim is to address these issues. This is done using current standard web technologies extended for real-time application (and structured using specific development guidelines) while ensuring compatibility with the manifold new evolutions in the currently ongoing development of open web platform (HTML5, websockets, etc). While our own work has mainly focused on synchronous co-located collaborative systems (same place/same time), our solution, the technologies used, as well as the concepts that are introduced are easily extendable for remote and/or asynchronous collaboration.     

Conceptual tools for planning for the wireless classroom

Abstract  Wireless and mobile devices are beginning to offer stunning new technical capabilities for collaborative learning. Yet, researchers in this field must recognise the importance of complementing these technical advances with improved understanding of the patterns of classroom activity that most need support. The approach taken in the work reported in this paper has been to create conceptual tools that help thinking and talking about technology-supported collaborative learning. A particularly powerful tool is Collaborative Design Patterns, which captures common learning situations and benefits in written form. This paper uses four classroom scenarios to describe eight patterns. These patterns fall into two categories: whole-activity patterns, which suggest ways to organise one or more class periods, and smaller-grained support patterns.     

Code talk: Student discourse and participation with networked handhelds

This study explores the potential of networked handheld computers to support collaborative problem solving in small groups. Drawing on data from a middle school mathematics classroom equipped with a wireless handheld network, I argue that the sharing of mathematical objects through interactive devices broadens the ‘bandwidth’ of classroom collaboration, expanding the range of participatory forms through which students might contribute to the work of a group and enhance their own learning. The analysis focuses on the participation strategies of those students in two focus groups who were most able to demonstrate posttest score gains from relatively low scores on a pretest. In particular, the device network provided those students with a set of collective, dynamic objects through which they supplemented and coordinated discursive forms of participation in the joint work of their respective groups.     

Design and validation of a light inference system to support embedded context reasoning

Embedded context management in resource-constrained devices (e.g. mobile phones, autonomous sensors or smart objects) imposes special requirements in terms of lightness for data modelling and reasoning. In this paper, we explore the state-of-the-art on data representation and reasoning tools for embedded mobile reasoning and propose a light inference system (LIS) aiming at simplifying embedded inference processes offering a set of functionalities to avoid redundancy in context management operations. The system is part of a service-oriented mobile software framework, conceived to facilitate the creation of context-aware applications—it decouples sensor data acquisition and context processing from the application logic. LIS, composed of several modules, encapsulates existing lightweight tools for ontology data management and rule-based reasoning, and it is ready to run on Java-enabled handheld devices. Data management and reasoning processes are designed to handle a general ontology that enables communication among framework components. Both the applications running on top of the framework and the framework components themselves can configure the rule and query sets in order to retrieve the information they need from LIS. In order to test LIS features in a real application scenario, an ‘Activity Monitor’ has been designed and implemented: a personal health-persuasive application that provides feedback on the user’s lifestyle, combining data from physical and virtual sensors. In this case of use, LIS is used to timely evaluate the user’s activity level, to decide on the convenience of triggering notifications and to determine the best interface or channel to deliver these context-aware alerts.     

Policy-based dynamic reconfiguration of mobile-code applications

Global wireless networks have opened the way to a ubiquitous Internet computing environment in which a variety of portable devices remain connected to the Internet fabric - even as their locations change continuously - and access to data and services is independent of both device type and location. In this environment, applications must be able to change the location of their execution. In addition, they must allow heterogeneous and resource-limited portable devices to download only the device-specific software components needed for execution. Code mobility enables dynamic customization and configuration of ubiquitous Internet applications. Mobility complicates application programming by requiring developers to define when and where to move which components under varying operating conditions. A policy-based implementation framework supports high-level reconfiguration strategies that separate mobility concerns from application functionality.     

A collaborative face-to-face design support system based on sketching and gesturing

Mobile and pervasive computing has seen a rapid development in the last years. Portable, handheld computing devices are getting more popular as their capabilities increase. Therefore, people having the need to work on-the-field have now the possibility to be supported by computer technology, for example, garden or building designers. Ad-hoc networking capabilities of handheld devices enable the development of supporting tools for collaborative work anywhere. This paper presents MCSketcher, a system that enables face-to-face collaborative design based on sketches using handheld devices equipped for spontaneous wireless peer-to-peer networking. It is especially targeted for supporting preliminary, in-the-field work, allowing designers to exchange ideas through sketches on empty sheets or over a recently taken photograph of the object being worked on, in a brainstorming-like working style. Pen-based designed human–computer interaction is the key to supporting collaborative work. The gestures-based command input results in a lightweight yet efficient and easy to use interface. Graph structured hierarchical documents help to overcome the problems of a small screen size.