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天气信息作为人们日常生活的重要信息具有不可替代性. 移动终端天气信息服务系统是采用Java技术在Android平台下,通过访问新浪云开放的天气API,调用新浪云服务,获取并在移动终端显示天气数据的一种“云端”应用系统,该系统具有响应快、天气数据精准的特点. 文章对移动终端天气信息服务系统的技术背景、系统总体设计,系统实现作了简要介绍.  相似文献   

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移动计算安全性   总被引:1,自引:1,他引:0  
1 引言安全性问题始终是开放系统中的一个核心问题,为此,国际标准化组织ISO曾对OSI环境(开放系统环境)的安全性作过深入的研究,并为其提出了安全体系的概念集。然而,随着移动计算技术的出现和广泛的应用,许多新的安全性同题出现了,给现有的操作系统、分布式系统管理、程序设计语言和中间件技术都带  相似文献   

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Mobile offloading is a promising technique to aid the constrained resources of a mobile device. By offloading a computational task, a device can save energy and increase the performance of the mobile applications. Unfortunately, in existing offloading systems, the opportunistic moments to offload a task are often sporadic and short-lived. We overcome this problem by proposing a social-aware hybrid offloading system (HyMobi), which increases the spectrum of offloading opportunities. As a mobile device is always co-located to at least one source of network infrastructure throughout of the day, by merging cloudlet, device-to-device and remote cloud offloading, we increase the availability of offloading support. Integrating these systems is not trivial. In order to keep such coupling, a strong social catalyst is required to foster user’s participation and collaboration. Thus, we equip our system with an incentive mechanism based on credit and reputation, which exploits users’ social aspects to create offload communities. We evaluate our system under controlled and in-the-wild scenarios. With credit, it is possible for a device to create opportunistic moments based on user’s present need. As a result, we extended the widely used opportunistic model with a long-term perspective that significantly improves the offloading process and encourages unsupervised offloading adoption in the wild.  相似文献   

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In this paper we describe a way to save and restore the state of a running Java program. We achieve this on the language level, without modifying the Java virtual machine, by instrumenting the programmer's original code with a preprocessor. The automatically inserted code saves the runtime information when the program requests state saving and re-establishes the program's runtime state on restart. The current preprocessor prototype is used in a mobile agent scenario to offer transparent agent migration for Java-based mobile agents, but could generally be used to save and re-establish the execution state of any Java program.  相似文献   

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Ubiquitous Computing promises seamless access to information anytime, anywhere with different and heterogeneous devices. This kind of environment imposes new challenges to software development. For example, information and user interface should be adapted according to contextual characteristics such as user, environment, and access device. In case of device adaptation, the development challenge is related to the heterogeneity of the devices, which requires software engineers to create different versions for each type of device and every platform. This paper proposes a MB-UID (model-based user interface development) approach for semi-automatic generation of adaptive applications for mobile devices. An environment, called XMobile, offers a device-independent user interface framework and a code generation tool for providing fast development of multi-platform and adaptive applications according to device and platform features. A case study is also presented to illustrate how the environment can be used for constructing an application for heterogeneous devices with different network connectivity modes.  相似文献   

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Android是Google推出了基于Linux的平台的开源手机操作系统,由于Google的战略,使得越来越多的手机开发商加入到了Google的开放手机联盟中.这也使得Android的手机越来越普及,也有更多的人参与到Android的开发当中去.现在更多的人开始接触Android,而在Android中碰到的问题也就会变的更多,更频繁.本文就是介绍下一些简单的Android程序中几个新手可能会出现的错误以及解决办法.  相似文献   

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提出了基于云的跨组织信息系统(CIOS)的信任产生和作用机制模型,并利用来自中国内地的256份有效样本数据对该模型进行了实证检验.结果表明信任于用户对CIOS的使用态度和意向有着重要的影响,而可靠性、可用性、可控性和互操作性是CIOS能否被信任的关键因素.基于研究发现对CIOS的研发与应用给出了若干建议.  相似文献   

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移动Agent系统Ajanta的分析与研究   总被引:1,自引:1,他引:0  
文章详细地分析了Ajanta系统的运行环境、体系结构、安全性与实现中的一些关键技术,并对该系统中存在的不足与可改进的方案进行了讨论。  相似文献   

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随着大数据时代的到来,应用数据量剧增,个性化推荐技术日趋重要。传统的推荐技术直接应用于大数据环境时会面临推荐精度低、推荐时延长以及网络开销大等问题,导致推荐性能急剧下降。针对上述问题,提出用户共现矩阵乘子推荐策略,将用户相似度矩阵与项目评分矩阵相乘得到用户对项目的预测评分矩阵,从而生成对每个用户的候选推荐项目集;在此基础上,根据分布式处理架构的特点对传统协同过滤算法进行并行化扩展,设计了基于用户的分布式协同过滤算法;最后通过重定义序列组合的MapReduce模式将多个子任务串联起来,自动地完成顺序化的执行。实验结果表明,该算法在分布式计算环境下具有良好的推荐精度和推荐效率。  相似文献   

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嵌入式移动数据库的应用研究   总被引:1,自引:0,他引:1  
随着移动技术的发展及智能移动终端的普及,嵌入式移动数据库技术目前已经从研究领域向广泛的应用领域发展,各种嵌入式移动数据库产品纷纷涌现.文章分析了嵌入式移动数据库管理系统及应用环境的特点、体系结构,介绍了嵌入式移动数据库系统在应用中必须要解决的问题以及目前的主要产品和应用.  相似文献   

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Uncertainty handling is one of the most important aspects of modelling of context-aware systems. It has direct impact on the adaptability, understood as an ability of the system to adjust to changing environmental conditions or hardware configuration (missing data), changing user habits (ambiguous concepts), or imperfect information (low quality sensors). In mobile context-aware systems, data is most often acquired from device’s hardware sensors (like GPS, accelerometer), virtual sensors (like activity recognition sensor provided by the Google API) or directly from the user. Uncertainty of such data is inevitable, and therefore it is obligatory to provide mechanisms for modelling and processing it. In this paper, we propose three complementary methods for dealing with most common uncertainty types present in mobile context-aware systems. We combine modified certainty factors algebra, probabilistic interpretation of rule-based model, and time-parametrised operators into a comprehensive toolkit for modelling and building robust mobile context-aware systems. Presented approach was implemented and evaluated on the practical use-case.  相似文献   

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基于Internet的移动Agent   总被引:6,自引:0,他引:6  
一前言 Agent技术源自人工智能,面向Agent的分析和设计方法,是新一代计算、编程风范,是面向对象OO技术的发展,被誉为“软件开发的又一重大突破”,“软件界的新革命”。各种软件Agent大量应用于各个领域,如个人助理、信息搜索、远程网络管理等。A-gent技术为解决开放性、分布性和复杂性的问题提供了新的途径。它能够以一种更自然、更容易、更高效的方法解决现有问题,而且能够涉足其它方法解决不好  相似文献   

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弹性移动云计算(Elastic Mobile Cloud Computing,EMCC)中,移动设备按照当前需求将部分计算任务迁移到云端执行,无缝透明地利用云资源增强自身功能。首先,在总结现有EMCC方案的基础上,抽象出通用的EMCC框架;指出EMCC程序中敏感模块的迁移会给EMCC带来隐私泄露、信息流劫持等安全风险;然后设计了融合风险管理的弹性移动云计算通用框架,该框架将安全风险看作EMCC的一种成本,保证EMCC的使用对用户来说是有利的;最后,指出风险管理的难点在于风险量化以及敏感模块标注。对此,设计了风险量化算法,实现了Android程序敏感模块自动标注工具,并通过实验证明了自动标注的准确性。  相似文献   

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It is reported that mobile users spend most of their time on texting SMS, Social Networking, Emailing, or sending instant messaging (IM), all of which involve text input. There are three primary text input modalities, soft keyboard (SK), speech to text (STT) and Swype. Each one of them engages a different set of hardware and consequently consumes different amounts of battery energy. Using high-precision power measurement hardware and systematically taking into account the user context, we characterize and compare the energy consumption of these three input modalities. We find that the length of interaction, or the message length, determines the most energy efficient modality. For short interactions, less than 14–30 characters, SK is the most energy efficient. For longer interactions, however, STT significantly outperforms both SK and Swype. When message length distributions of popular text activities are considered, STT provides near optimal energy consumption without requiring the user to predict the message length and decide between SK and STT. In terms of battery life, the choice of input modality makes significant differences. If users always choose SK for all their text activities, they will consume nearly 50% of the phone battery each day. Choosing STT over SK can save 30%–40% of the battery depending on the choice of STT software.  相似文献   

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This paper presents a stochastic dynamic load balancing algorithm for Internet computing, which is a new type of distributed computing involving heterogeneous workstations from different organizations on the Internet. To realize the practical environment, we assume the system to be comprised of heterogeneous, untrusted and non‐dedicated workstations connected by a non‐dedicated network. Our algorithm uses the product of the average processing time and the queue length of system jobs as the load index. Dynamic communication delay is included in the execution cost calculation. The transfer policy and the location policy are combined in a stochastic algorithm. State information exchange is done via information feedback and mutual updating. Simulations demonstrate that our algorithm outperforms conventional approaches over a wide range of system parameters. These results are reconfirmed by empirical experiments after we have implemented the algorithms on the Distributed Java Machine global virtual machine. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

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支持处理移动实时只读事务的更新分发协议   总被引:2,自引:0,他引:2  
研究了移动实时计算环境下更新分发的问题,提出了混合前向多版本数据广播方案,该方案在保证事务一致性的同时满足了数据和事务本身的定时约束,模拟实验表明该方案能够有效地降低事务错过率和提高数据流行性。  相似文献   

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为了解决现有纸质投票系统统计效率低的问题,解决专用投票系统升级困难,使用率不高的问题,本系统设计了以安卓端为客户端,电脑端为服务器端的手机投票系统,该系统实现了在客户端进行登录投票,查询候选列表的信息并且能够有效的防止刷票,服务器端进行活动的发起,制定活动的相关规则,查看投票结果等功能。  相似文献   

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Android应用程序的主体采用Java编程语言实现,Java语言的一个显著特点是它通过Java虚拟机和垃圾回收机制管理大部分的内存事务,但是在Java程序中不可避免地存在着内存泄漏的问题。本文从造成Android应用程序内存泄漏的原因入手,对内存泄漏进行检测和定位。阐述了在编写应用程序时规避内存泄漏的方法,并分别介绍了一种内存监测工具和一种内存分析工具的使用方法。  相似文献   

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Continuously identifying a user’s location context provides new opportunities to understand daily life and human behavior. Indoor location systems have been mainly based on WiFi infrastructures which consume a great deal of energy mostly due to keeping the user’s WiFi device connected to the infrastructure and network communication, limiting the overall time when a user can be tracked. Particularly such tracking systems on battery-limited mobile devices must be energy-efficient to limit the impact on the experience of using a phone. Recently, there have been a lot of studies of energy-efficient positioning systems, but these have focused on outdoor positioning technologies. In this paper, we propose a novel indoor tracking framework that intelligently determines the location sampling rate and the frequency of network communication, to optimize the accuracy of the location data while being energy-efficient at the same time. This framework leverages an accelerometer, widely available on everyday smartphones, to reduce the duty cycle and the network communication frequency when a tracked user is moving slowly or not at all. Our framework can work for 14 h without charging, supporting applications that require this location information without affecting user experience.  相似文献   

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