A scalable architecture for 3D map navigation on mobile devices

Mobile devices such as smart phones or tablets are rapidly increasing their graphics and networking capabilities. However, real-time visualization of 3D maps is still a challenging task to accomplish on such limited devices. In this paper, we describe the principles involved in the design and development of a scalable client–server architecture for delivering 3D maps over wireless networks to mobile devices. We have developed a hybrid adaptive streaming and rendering method that distributes the 3D map rendering task between the mobile clients and a remote server. This architecture provides support for efficient delivery of 3D contents to mobile clients according to their capabilities. As a proof of concept, we have implemented a prototype and carried out exhaustive experiments considering different scenarios and hundreds of concurrent connected clients. The analysis of the server workload and the mobile clients performance show that our architecture achieves a great scalability and performance even when using low-end hardware.     

Studying energy trade offs in offloading computation/compilation in Java-enabled mobile devices

Java-enabled wireless devices are preferred for various reasons. For example, users can dynamically download Java applications on demand. The dynamic download capability supports extensibility of the mobile client features and centralizes application maintenance at the server. Also, it enables service providers to customize features for the clients. In this work, we extend this client-server collaboration further by offloading some of the computations (i.e., method execution and dynamic compilation) normally performed by the mobile client to the resource-rich server in order to conserve energy consumed by the client in a wireless Java environment. In the proposed framework, the object serialization feature of Java is used to allow offloading of both method execution and bytecode-to-native code compilation to the server when executing a Java application. Our framework takes into account communication, computation, and compilation energies to decide where to compile and execute a method (locally or remotely), and how to execute it (using interpretation or just-in-time compilation with different levels of optimizations). As both computation and communication energies vary based on external conditions (such as the wireless channel state and user supplied inputs), our decision must be done dynamically when a method is invoked. Our experiments, using a set of Java applications executed on a simulation framework, reveal that the proposed techniques are very effective in conserving the energy of the mobile client.     

An open and scalable architecture for delivering 3D shared visualization services to heterogeneous devices

Shared visualization environments represent an effective means to enhance collaborative work in engineering and scientific design tasks. The availability of high‐speed networks allows researchers to work together from geographically distributed locations, and mobile devices are able to carry out ubiquitous 3D visualization tasks through wireless network connections. This paper presents a scalable architecture for the delivery of shared 3D visualization services to heterogeneous terminals ranging from powerful workstations to mobile devices such as PDAs and smart‐phones. The framework design allows both desktop and mobile clients to simultaneously visualize the same model by sharing a common view. Remote‐rendering servers support effective visualization on thin clients, and a load balancing mechanism provides efficient resource usage. Copyright © 2011 John Wiley & Sons, Ltd.     

Android平台上的多用户无线投影控制系统设计

运用WIFI无线通信技术、ARM Cortex A8处理器嵌入式系统、TCP/IP协议以及无线局域网监控等技术设计并制作了一个Android平台的多用户无线投影控制系统。通过WIFI无线通信技术建立用户端与无线投影网关的无线通信,解决了数据连线对投影仪使用时的限制,极大地方便了有线投影仪用户使用无线投影功能。本系统通过无线局域网实现多用户、多平台的无线投影,采用一主多从的方式进行切换,适用于PC机和Android手持移动设备。系统经测试,达到使用要求。本文还详细描述了无线投影网关设计和无线投影管理软件设计。     

基于Android平台的移动图书馆客户端设计与实现

在智能手机软件不断发展的今天,很多传统PC机上的应用正在向智能手机客户端转移。基于Android平台和智能手机的移动图书馆系统实现了客户端与服务器的通讯,使得用户可以通过手机客户端访问和查询各类图书信息。设计了系统框架及功能模块,描述通过无线通信实现客户端与服务器间的通讯的方法,并列出主要模块的实现算法。     

Navigating large terrains using commodity mobile devices

We describe a hybrid client-server technique for remote adaptive streaming and rendering of large terrains in resource-limited mobile devices. The technique has been designed to achieve an interactive rendering performance on a mobile device connected to a low-bandwidth wireless network. The rendering workload is split between the client and the server. The terrain area close to the viewer is rendered in real-time by the client. The terrain located far from the viewer is portrayed as view-dependent impostors, rendered by the server on demand. A prototype has been built and an exhaustive set of experiments covering several platforms, wireless networks and a wide range of viewer velocities has been conducted. Results show that the approach is feasible, effective and robust.     

Interactive visualization of medical volume models in mobile devices

Interactive visualization of volume models in standard mobile devices is a challenging present problem with increasing interest from new application fields like telemedicine. The complexity of present volume models in medical applications is continuously increasing, therefore increasing the gap between the available models and the rendering capabilities in low-end mobile clients. New and efficient rendering algorithms and interaction paradigms are required for these small platforms. In this paper, we propose a transfer function-aware compression and interaction scheme, for client-server architectures with visualization on standard mobile devices. The scheme is block-based, supporting adaptive ray-casting in the client. Our two-level ray-casting allows focusing on small details on targeted regions while keeping bounded memory requirements in the GPU of the client. Our approach includes a transfer function-aware compression scheme based on a local wavelet transformation, together with a bricking scheme that supports interactive inspection and levels of detail in the mobile device client. We also use a quantization technique that takes into account a perceptive metrics of the visual error. Our results show that we can have full interaction with high compression rates and with transmitted model sizes that can be of the order of a single photographic image.     

渲染器与Web服务器耦合实现远程体 渲染的交互优化

目的 为使用户随时随地获得需要较大计算和存储资源的交互真实感体渲染服务,设计并实现了一种面向Web的远程真实感体渲染方法。方法 计算量较大的实时体渲染任务由远端渲染服务器中的GPU加速完成并通过WebSocket将渲染图像发送至客户端;客户端浏览器只需负责接收显示渲染图像并监听发送用户交互事件。提出了一种输出系统耦合算法用以连接输出图像速率较大的渲染服务器和发送图像速率较慢的Web服务器。算法能根据Web服务器发送图像的情况动态调整每次图像输出的迭代计算次数,改变渲染服务器输出图像的时间间隔以达到与Web服务器发送速度相平衡,同时保持渲染服务器持续工作。结果 实验比较了在不同网络传输条件下,采用输出系统耦合算法与直接连接渲染器和Web服务器,渲染4个不同数据集所需的完成时间及帧率等性能评价指标。在局域网和广域网环境下,本文方法分别最多只需17 s和14 s即可完成整个渲染过程,而采用直接连接渲染器和Web服务器的方法则分别至少需要31 s和60 s才能完成整个渲染过程。实验结果表明采用输出系统耦合算法在不同网络条件下均可较大地缩短整个渲染过程所需时间,使用户在较短时间内获得高质量渲染图像。结论 本文渲染器与Web服务器耦合实现远程体渲染交互优化的方法可让用户使用与计算能力无关的桌面或移动设备通过网络透明使用高性能渲染系统;系统采用的输出系统耦合算法能够根据网络承载能力自适应调整渲染器输出速度,使用户在不同的网络环境中均可以较快的速度获得高质量渲染图像。     

GPU-based remote visualization of dynamic molecular data on the web

Visualization of dynamic data from molecular dynamics simulations is crucial for understanding the functioning of molecules. Many existing visualization tools have mainly focused on supporting a single user working on a desktop computer. Technical advancements in browser features increase the potential for the development of web-based collaborative visualization tools. Although web-based molecular viewers already exist, their support for dynamic molecular data at interactive rates is lacking. To address this gap, we present an efficient web application for visualization of dynamic molecular data using WebGL that exploits HTML5 technologies like WebSockets and Web Workers. GPU-based ray casting techniques offer fast rendering times and produce images with higher visual quality. Efficient data encoding techniques are used to minimize the data transferred to the client; therefore saving bandwidth and improving the transfer times. We demonstrate the feasibility of visualizing large dynamic molecular data with more than one million atoms in the browser at interactive frame rates. Our approach allows scientists at arbitrary locations to concurrently visually analyze the same data. The interactive parameterization of the visualization can be shared among multiple clients, providing the basis for collaborative research. Moreover, the application can be employed for remote simulation monitoring on mobile devices.     

基于Web Service的分布式协同CAD系统框架

采用XML定义了基于Web Service分布式协同CAD系统框架中服务器端和客户端之间特征操作和协同设计的通信协议．该系统以特征为基本协同设计单元，服务器端和客户端之间采用增量式特征信息交互，降低网络流量，增强了系统的响应能力．由于系统基于Web Service构造，因此可以支持跨异构平台协同设计，原型系统的应用表明，该系统可以较好地支持分布式条件下的协同设计。     

Mobile agents for information retrieval in hybrid simulation environment

In this paper, we propose a hybrid simulation environment that incorporates with wired/wireless networks, IEEE standard 1516 high-level architecture (HLA), and IBM Aglets mobile agent system. Therefore, HLA simulations are not restricted to be participated solely by using desktop computers with cable connections. Users can use a wide variety of devices to join in HLA simulations and explicitly exclude from junk data in terms of a personalized data filtering policy. Based on data correlation between HLA objects and a client's data filtering policy, we employ the simulation environment manager in distributing a client to an appropriate federate server (FS). In particular, a mobile agent, namely data filtering agent, is devised to temporarily reside at the FS to perform mobile agent-based data distribution management for clients. As a result, the clients can receive the most interested information corresponding to their pre-defined data filtering policies. Once either the data transmission quality within the wireless network is degraded below a threshold or the clients abnormally modify the data filtering policies, their own mobile agents carry out migrations to provide the users with the ubiquitous and seamless services. Consequently, the users can use any mobile device as well as using a desktop computer in a stationary point to participate in the HLA simulations. The experimental results also show that the proposed mobile agent-based data distribution can raise adaptability and applicability to large-scale HLA simulations.     

Feature-based design in a distributed and collaborative environment

In this paper, a client/server framework has been developed to enable a dispersed team to accomplish a feature-based design task collaboratively. A manipulation client+modelling server infrastructure has been proposed to facilitate consistent primary information modelling for multiple users and adaptability of the system. Based on feature-to-feature relationships, a distributed feature manipulation mechanism has been proposed to filter the varied information of a working part during a co-design activity to avoid unnecessary re-transferring of the complete large-size CAD files each time when any interactive operation is imposed on the model by a client. In the distributed environment, a design task and the engaged clients are organised and connected through working sessions generated and maintained dynamically with a collaborative server. The environment is open to downstream manufacturing analysis modules to achieve distributed concurrent engineering.     

Metacomputing with Mobile Agents

In this paper we present Parallel Computing with Mobile Agents (PaCMAn), a mobile agent based Metacomputer that enables its users to utilize idle resources on the internet to tackle computational problems that could not be handled efficiently with their own resources. The PaCMAn launches multiple mobile agents that cooperate and communicate to solve problems in parallel. Each agent supports the basic communication and synchronization tasks of the classical parallel worker assuming the role of a process in a parallel processing application. Application tasks, however, are assigned dynamically to the PaCMAn’s mobile agents via TaskHandlers. TaskHandlers are Java objects capable of implementing particular tasks of the application. The PaCMAn consists of three major components: Broker, Server and Client. A server machine has to be explicitly registered in order to take part in the PaCMAn Metacomputer. A number of brokers keep track of the available resources. In the PaCMAn system both server and client machines can be located anywhere in the Internet. The clients select the servers that they will utilize based on the specific resource requirements. We have developed and tested prototype systems with several applications. These prototypes provide proof of concept of our proposed Metacomputing philosophy. Furthermore they have demonstrated that PaCMAn provides parallel efficiency. We also demonstrate that the PaCMAn Metacomputer can be used as the computational engine for the creation of sophisticated Pervasive Services anywhere anytime.     

图形化在线建模的OPC UA网关设计

OPC统一架构(Unified Architecture,UA)已经成为工业4.0的核心通信接口规范,但由于工业领域设备更新缓慢,大量现场设备仍使用传统的通信协议,且设备生产厂家不同,使用的通信协议也可能不同.为了将不同类型的现场设备融入OPC UA架构,克服多种通信协议之间的数据交换壁垒,本文设计了一种支持图形化在线建模的OPC UA网关.网关内部实现了OPC UA服务器,能够将多种通信协议数据连接到OPC UA服务器地址空间的节点上,方便MES和ERP等管理软件进行高效数据访问.同时,为了便于使用者建立OPC UA信息模型以及配置网关数据采集逻辑,设计了一种图形化建模方法.最后,本文通过示例,验证了图形化在线建模网关的可用性.     

A dynamic binary translation system in a client/server environment

With rapid advances in mobile computing, multi-core processors and expanded memory resources are being made available in new mobile devices. This trend will allow a wider range of existing applications to be migrated to mobile devices, for example, running desktop applications in IA-32 (x86) binaries on ARM-based mobile devices transparently using dynamic binary translation (DBT). However, the overall performance could significantly affect the energy consumption of the mobile devices because it is directly linked to the number of instructions executed and the overall execution time of the translated code. Hence, even though the capability of today’s mobile devices will continue to grow, the concern over translation efficiency and energy consumption will put more constraints on a DBT for mobile devices, in particular, for thin mobile clients than that for severs. With increasing network accessibility and bandwidth in various environments, it makes many network servers highly accessible to thin mobile clients. Those network servers are usually equipped with a substantial amount of resources. This provides an opportunity for DBT on thin clients to leverage such powerful servers. However, designing such a DBT for a client/server environment requires many critical considerations.In this work, we looked at those design issues and developed a distributed DBT system based on a client/server model. It consists of two dynamic binary translators. An aggressive dynamic binary translator/optimizer on the server to service the translation/optimization requests from thin clients, and a thin DBT on each thin client to perform lightweight binary translation and basic emulation functions for its own. With such a two-translator client/server approach, we successfully off-load the DBT overhead of the thin client to the server and achieve a significant performance improvement over the non-client/server model. Experimental results show that the DBT of the client/server model could achieve 37% and 17% improvement over that of non-client/server model for x86/32-to-ARM emulation using MiBench and SPEC CINT2006 benchmarks with test inputs, respectively, and 84% improvement using SPLASH-2 benchmarks running two emulation threads.     

Database support for mobile route planning systems

The impact of tele and mobile information technology will increase the need for fast access to geodata significantly in the next years. However, hitherto many problems concerning the wireless access to geodata e.g. to be used in route planning clients are not yet solved. Beside transaction management the requirements of route planning systems to GIS technology mainly concern the modelling and management of graph-based geodata. New challenges to meet are the efficient storage of routes and the supply of location-based database queries. However, today's first commercial database management systems for mobile devices do not support spatial database queries. In this article we collect requirements and present a first implementation prototype of a mobile route planning system focusing on the support of spatial database queries. First experiences with a mobile bicycle route planning client coupled with a database management system are presented. We show that at the server side the computation and storage of different route types as well as the generation of routes under consideration of semantic information like tourist information or roads with certain points of interest should make up the main functionality of such a system. The mobile client should supply database support for the location-based visualization of routes and an offline data management of route data.     

SPECSA: a scalable, policy-driven, extensible, and customizable security architecture for wireless enterprise applications

This paper presents SPECSA, a new, optimized, policy-driven security architecture for wireless enterprise applications. SPECSA is scalable, extensible, flexible, and customizable. It supports end-to-end client authentication, data integrity and confidentiality between wireless clients and enterprise servers. The security services provided by SPECSA are customized and controlled by an easily configurable security policy that specifies several security-related attributes, classifies network data based on sensitivity and content, and provides an abstraction for the communication and messaging between the client and the server. In addition, SPECSA provides a standard Application Programming Interface (API) that conceals to a great extent the complexity of security operations and programming from the application developer who may not be experienced with enterprise security programming. SPECSA was designed in a platform-neutral manner and can be implemented on a wide range of wireless clients ranging from low-end platforms such as the Java 2 Mobile Edition/Connected Limited Device Configuration (J2ME/CLDC) on limited-memory mobile devices to Personal Java and the Net Compact Framework on PDAs. On the server side, SPECSA can be implemented on any of the available enterprise server platforms. A sample implementation of SPECSA was developed for J2ME on the client-side and for Java 2 Enterprise Edition (J2EE) on the server-side.     

基于无线传感网络的环境监测系统

无线传感器网络是目前环境监测领域研究的热点技术。结合ZigBee和无线传感网络设计了集多种功能于一体的完整环境监测系统。在本系统中,节点选用CC2530芯片作为zigbee通信模块,网关采用GPRS作为系统与3G网络的通信模式。系统实现了采集温度、湿度、光线亮度等环境信息,并进行了相应处理,设计了网关数据处理软件算法。系统具体的工作方式为：传感器节点对室内的环境信息进行采集并将数据以ZigBee无线自组网方式发送到无线传感网络的控制中心网关,网关负责将传感器数据处理后上传到云服务器;用户能够通过手机APP和网页查看,对于重要的警告信息网关会发短信到用户的手机,而服务器端会发邮件或微博提醒用户。经过测试和使用,本系统运行可靠,能准确获取环境数据,网关和服务器端数据能够实时更新,环境参数能实现自动调节与校准。     

基于Mobile Agent的协作式反垃圾邮件系统设计

提出一种基于Mobile Agent技术的协作式反垃圾邮件体系结构，并对由代理服务器、反垃圾邮件客户端、动态负载均衡层、Mobile Agent层及反垃圾邮件服务器组成的五层结构进行阐述；代理服务器用来解决对邮件服务器的统一访问，降低由邮件服务器及客户端的多样性带来的系统复杂度；使用Nilsimsa算法实现相似邮件Hash过滤；最后对协作式反垃圾系统进行测试。     

基于开源软硬件的智能家居系统设计与实现

针对目前智能家居系统中存在的问题．设计并实现一种基于开源软硬件的智能家居系统。采用树莓派作为系统的嵌入式网关和服务器．开源硬件Arduino控制器作为控制终端,实现对家居各种信息的检测和设备的控制。采用Wi—Fi,蓝牙等无线通信模块建立家庭内部无线网络．实现各模块之间的无线通信。同时设计网页和手机客户端,使用用户能够远程对家中的情况进行监控．同时对家电进行控制。