基于单片机的可编程转换法优化控制

频-时域智能传感器的最主要组成部分之一是频率,这种频率转换器直接影响测量性能。本文以比例计数的频率-编码转换方式为例,介绍了其频率转换过程,以及如何用单片机微控制器实现基于可编程转换法(PCM)的频率-编码转换的最优控制过程。     

Context- and social-aware middleware for opportunistic networks

Opportunistic networks are multi-hop ad hoc networks in which nodes opportunistically exploit any pair-wise contact to share and forward content, without requiring any pre-existing Internet infrastructure. Opportunistic networks tolerate partitions, long disconnections, and topology instability in general. In this challenging environment, leveraging users’ mobility represents the most effective way to deliver content to interested users. In this paper we propose a context- and social-aware middleware that autonomically learns context and social information on the users of the network, and that uses this information in order to predict users’ future movements. In order to evaluate the proposed middleware on a realistic scenario, we have designed and implemented a context- and social-aware content sharing service, exploiting the functionality of the middleware. Both the middleware and the content sharing service have been integrated with an existing data-centric architecture (the Haggle architecture) for opportunistic networks. Finally, we have validated the proposed content sharing application on a small-scale testbed and, on a larger scale, we have investigated the advantages provided by context- and social-aware sharing strategies by means of extensive simulations. The main result of this paper is the definition and implementation of a context- and social-aware middleware able to share context information with all the interested components improving the efficiency and performances of services and protocols in opportunistic networks. With respect to content sharing strategies that do not exploit context and social information, we have obtained up to 200% improvements in terms of hit rate (probability that users receive the content they request) and 99% reduction in resource consumption in terms of traffic generated on the network.     

从Unicode到GBK的内码转换

讨论了GB，GBK，Big5。Unicode编码以及内码转换原理和方法，介绍了在手机的TTS系统下把Unicode码转换成GBK码的方法，并使用代码页CP936中Unicode码和GBK码的对应关系实现了从Unicode码到GBK码的内码转换。     

Secure proof of storage with deduplication for cloud storage systems

Explosion of multimedia content brings forth the needs of efficient resource utilization using the state of the arts cloud computing technologies such as data deduplication. In the cloud computing environments, achieving both data privacy and integrity is the challenging issue for data outsourcing service. Proof of Storage with Deduplication (POSD) is a promising solution that addresses the issue for the cloud storage systems with deduplication enabled. However, the validity of the current POSD scheme stands on the strong assumption that all clients are honest in terms of generating their keys. We present insecurity of this approach under new attack model that malicious clients exploit dishonestly manipulated keys. We also propose an improved POSD scheme to mitigate our attack.     

Robuste multikriterielle Dienstkomposition in Informationssystemen

Service compositions are used to implement business processes in a variety of application domains. A quality of service (QoS)-aware selection of the service to be composed involves multiple, usually conflicting and possibly uncertain QoS attributes. A multi-criteria solution approach is desired to generate a set of alternative service selections. In addition, the uncertainty of QoS-attributes is neglected in existing solution approaches. Hence, the need for service reconfigurations is imposed to avoid the violation of QoS restrictions. The researched problem is NP-hard. This article presents a heuristic multi-criteria service selection approach that is designed to determine a Pareto frontier of alternative service selections in a reasonable amount of time. Taking into account the uncertainty of response times, the obtained service selections are robust with respect to the constrained execution time. The proposed solution approach is based on the Non-dominated Sorting Genetic Algorithm (NSGA)-II extended by heuristics that exploit problem specific characteristics of the QoS-aware service selection. The applicability of the solution approach is demonstrated by a simulation study.     

面向服务的Agent交互体系设计

基于Agent内部抽象与外部抽象,提出面向服务的社会Agent体系模型及Agent交互体系。通过功能层与知识层的分离,实现描述-控制机制,针对Agent服务交互,划分服务发现、服务协商、服务协调、服务执行与服务组织等基本交互阶段,采用黑板结构集成处理这些阶段的交互模块。分析结果表明,该模型以及交互体系能最大程度地利用服务语义,可用于Agent应用的系统化、工程化开发。     

NDT-6D for color registration in agri-robotic applications

Registration of point cloud data containing both depth and color information is critical for a variety of applications, including in-field robotic plant manipulation, crop growth modeling, and autonomous navigation. However, current state-of-the-art registration methods often fail in challenging agricultural field conditions due to factors such as occlusions, plant density, and variable illumination. To address these issues, we propose the NDT-6D registration method, which is a color-based variation of the Normal Distribution Transform (NDT) registration approach for point clouds. Our method computes correspondences between pointclouds using both geometric and color information and minimizes the distance between these correspondences using only the three-dimensional (3D) geometric dimensions. We evaluate the method using the GRAPES3D data set collected with a commercial-grade RGB-D sensor mounted on a mobile platform in a vineyard. Results show that registration methods that only rely on depth information fail to provide quality registration for the tested data set. The proposed color-based variation outperforms state-of-the-art methods with a root mean square error (RMSE) of 1.1–1.6 cm for NDT-6D compared with 1.1–2.3 cm for other color-information-based methods and 1.2–13.7 cm for noncolor-information-based methods. The proposed method is shown to be robust against noises using the TUM RGBD data set by artificially adding noise present in an outdoor scenario. The relative pose error (RPE) increased $~$14% for our method compared to an increase of $~$75% for the best-performing registration method. The obtained average accuracy suggests that the NDT-6D registration methods can be used for in-field precision agriculture applications, for example, crop detection, size-based maturity estimation, and growth modeling.     

Longitudinal deep truck: Deep longitudinal model with application to sim2real deep reinforcement learning for heavy-duty truck control in the field

To develop cooperative adaptive cruise control (CACC), the choice of control approach often influences and can limit the choice of model structure, and vice versa. For heavy-duty trucks, practical application of CACC in the field is heavily influenced by the accuracy of the used model. Deep learning and deep reinforcement learning (deep-RL) have recently been used to demonstrate improved modeling and control performance for vehicles such as cars and quadrotors compared to state-of-the-art. The literature on the application of deep learning and deep-RL for heavy-duty trucks in the field, which are significantly more complex than cars, is still sparse, however. In this article, we develop a two-layer gray-box deep learning model to capture longitudinal dynamics of heavy-duty trucks while abstracting their complexity and present an approach to properly break the nested feedback loops in the model for training. We compare this model with three other alternative models and show that it achieves $~10x$ better general performance compared to a standard artificial neural network and results in $~4x$ and $~40x$ slower steady-state acceleration and speed error growth rates, respectively. We then present an architecture to utilize these deep learning models within the deep-RL framework and use it to develop baseline CACC controllers that can be zero-shot transferred to the field. To carry out the work, we present a setup of differently configured trucks along with their interface architecture and stochastic driving cycle generators for data collection. Numerical validation of the approach demonstrated stationary and bounded modeling error, and demonstrated transfer of CACC controllers with consistent overshoot bounds and a stable approximately-zero steady-state error. Validation from field experiments demonstrated similarly consistent results. Compared to a state-of-the-art benchmark, the deep-RL controller achieved lower speed and time-gap error variance but higher time-gap error offset.     

Adaptive Zugriffskontrollverfahren

IT service providers are increasingly hosting different services of different customers on a shared IT infrastructure. While this fosters utilization of hardware infrastructure, system malfunctions, unexpected service behaviour or peak demands for one or more services may exploit resource pools (CPU, I/O, main memory, bandwidth etc.), entailing rejection of service requests. In this paper we describe models for dynamic admission control on shared infrastructures. The admission control model decides whether to accept, buffer or reject a service request based on the revenue, Service Level Agreements (SLAs) and its resource demand in comparison to the actual workload to maximize overall revenue. Simulations of a media streaming infrastructure have been used for evaluation and comparison with traditional admission control policies.     

MIMOSA: context-aware adaptation for ubiquitous web access

The ubiquitous computing scenario is characterized by heterogeneity of devices used to access services, and by frequent changes in the user’s context. Hence, adaptation according to the user’s context and the used devices is necessary to allow mobile users to efficiently exploit Internet-based services. In this paper, we present a distributed framework, named MIMOSA, that couples a middleware for context-awareness with an intermediary-based architecture for content adaptation. MIMOSA provides an effective and efficient solution for the adaptation of Internet services on the basis of a comprehensive notion of context, by means of techniques for aggregating context data from distributed sources, deriving complex contextual situations from raw sensor data, evaluating adaptation policies, and solving possible conflicts. The middleware allows programmers to modularly build complex adaptive services starting from simple ones, and includes tools for assisting the user in declaring her preferences, as well as mechanisms for detecting incorrect system behaviors due to a wrong choice of adaptation policies. The effectiveness and efficiency of MIMOSA are shown through the development of a prototype adaptive service, and by extensive experimental evaluations.     

Web Service Orchestration in Public Administration: Challenges, Roles, and Growth Stages

Public managers are looking for ways to fully exploit the advantages of Web services and Web services orchestration technology for improving service delivery. This article analyzes the quest toward the creation of citizen-centric, cross-agency processes using Web service orchestration technology. Based on pilot projects in the Netherlands, the authors find that the use of Web service orchestration technology requires the introduction of new process orchestration roles and an evolution from hierarchical to agreement-driven relationships. Eight process orchestration roles and a stage model developed by the authors are presented.     

基于SOA的企业IT架构

针对当前企业的信息化建设,提出并实现基于面向服务体系结构的企业应用集成系统架构,该架构采用企业服务总线无缝集成应用,支持流程服务编排,能进行组合服务开发,使企业可通过集成系统所提供的各种服务将其内部及企业间的应用集成在一起,并通过工作流的协调来互相调用,以实现一个完整的、跨组织的业务目标。     

Collaborative service system design for music content creation

This article presents a novel collaborative service system (CSS) design methodology supporting the work of multiple participating users and collaborative services processes. The CSS application of music content creation paradigm called DesignStorming as it pertains to CSS modeling and developing. CSS is an interactive service system that can be systematic service innovation and automatic semi-automated value co-creation between service providers and customers to enhance service productivity. The objectives of this research are threefold─to propose a novel design methodology for CSS, to incorporate simple service machine (SSM) and intelligent service machine (ISM) for CSS, and to demonstrate a CSS application of music content creation. SSM is a road map that can be used to define the salient attribute elements for CSS design. According to the predefined SSM, ISM conducts modeling the cognitive process of service exchanges and service provision, their knowledge representations, and value co-production process for a computerized CSS. DesignStorming demonstrates how a CSS can be automated the interactive communications and problem solving processes during the music content creation work. The CSS application involves the three system components: 1) Ontology Developer, 2) SFGA Partnership Matcher, and 3) Co-created Value Appraiser. In addition, a service evaluation model is described and evaluated, so that some of their important characteristics can be identified. Such a comprehensive design methodology can provide the foundation for building future more diversified and innovative collaborative service system.     

Cooperative content dissemination in multi-channel WLAN hotspots

It is common for hotspots in airports, cafes, and malls to deploy info-stations on their access points to provide local information such as flight schedule, multimedia access, sales and discount deals. The dissemination service, however, is limited by the wireless throughput in hotspots and cannot scale to a large number of users. This paper designs a new architecture that significantly improves the throughput of info-stations. We observe that usually the number of collocated info-stations is smaller than the number of orthogonal channels in IEEE 802.11, leaving some orthogonal channels unused, and thus wasting their capacity. We also observe that many users of an info-station download the same objects. Thus, we advocate an architecture, called hybrid-WLAN (H-WLAN), where mobile nodes can retrieve objects (multimedia content or information) from the info-station in the infrastructure mode, or exploit the idle 802.11 channels to cooperatively share their content with neighboring nodes in an ad-hoc manner. Our H-WLAN contains two components. The first component directs each object request to a nearby ad-hoc node that has the requested object, while avoids overloading any of the nodes. The second component balances the load across channels taking into account the popularity of the disseminated objects. We evaluate our design via simulations. The results show that our H-WLAN improves channel utilization and provides significantly higher throughput.     

针对P2P网络中DHT的DoS攻击技术研究

本文分析了基于分布式哈希表查找的大规模P2P系统的固有安全问题,提出了一种针对分布式哈希表系统利用算法复杂度进行DoS攻击的方法,并阐述了执行攻击的条件和构造这类攻击的方法,最后结合P2P网络发展趋势总结了此类攻击方法的局限性和进一步的研究方向。     

Intelligent shared-segment protection

Progress in network technologies and protocols is paving the road towards flexible optical transport networks, in which dynamic leasable circuits could be set up and released on a short-term basis according to customers’ requirements.Recently, new solutions for automatized network management promise to allow customers to specify the terms of the service level agreement (SLA) to be guaranteed (with different price range) by the service provider. In this paper we consider that these service level specifications (SLS), since they are now made available on-demand during the connection request, could be exploited to retrieve useful information able to improve the routing efficiency.In particular, we propose to exploit the knowledge of connection holding time, among the other SLS, to develop a novel intelligent approach for shared-segment protection (SSP).We will exploit the knowledge of the holding-time of connection requests to minimize resource overbuild due to backup capacity and hence to achieve resource-usage efficiency. For a typical US nationwide network, we compare our two proposed holding-time aware approaches to the respective two holding-time-unaware approaches: both of them, even in their holding-time unaware version, have been shown to be very efficient solutions for shared-segment protection. Nonetheless, we have obtained additional savings on resource overbuild of up to 11% for practical scenarios exploiting holding-time knowledge.     

Service feature modeling: modeling and participatory ranking of service design alternatives

The design of software-intensive service systems involves and affects numerous stakeholders including software engineers, legal and business experts as well as a potentially large number of consumers. In consequence, the challenge arises to adequately represent the interests of these groups with respect to service design decisions. Specifically, shared service design artifacts and participatory methods for influencing their development in consensus are required, which are not yet state of the art in software service engineering. To this end, we present service feature modeling. Using a modeling notation based on feature-oriented analysis, our approach can represent and interrelate diverse service design concerns and capture their potential combinations as service design alternatives. We further present a method that allows stakeholders to rank service design alternatives based on their preferences. The ranking can support service engineers in selecting viable alternatives for implementation. To exploit this potential, we have implemented a toolkit to enable both modeling and participative ranking of service design alternatives. It has been used to apply service feature modeling in the context of public service design and evaluate the approach in this context.     

The Nexus Approach to Integrating Multithreading and Communication

Lightweight threads have an important role to play in parallel systems: they can be used to exploit shared-memory parallelism, to mask communication and I/O latencies, to implement remote memory access, and to support task-parallel and irregular applications. In this paper, we address the question of how to integrate threads and communication in high-performance distributed-memory systems. We propose an approach based on global pointer and remote service request mechanisms, and explain how these mechanisms support dynamic communication structures, asynchronous messaging, dynamic thread creation and destruction, and a global memory model via interprocessor references. We also explain how these mechanisms can be implemented in various environments. Our global pointer and remote service request mechanisms have been incorporated in a runtime system called Nexus that is used as a compiler target for parallel languages and as a substrate for higher-level communication libraries. We report the results of performance studies conducted using a Nexus implementation; these results indicate that Nexus mechanisms can be implemented efficiently on commodity hardware and software systems.     

Quality-of-service mapping mechanism for packet video indifferentiated services network

This paper presents a futuristic framework for quality-of-service (QoS) mapping between practically categorized packet video and relative differentiated service (DiffServ or DS) network employing unified priority index and adaptive packet forwarding mechanism under a given pricing model (e.g., DiffServ level differentiated price/packet). Video categorization is based on the relative priority index (RPI), which represents the relative preference per each packet in terms of loss and delay. We propose an adaptive packet forwarding mechanism for a DiffServ network to provide persistent service differentiation. Effective QoS mapping is then performed by mapping video packets onto different DiffServ levels based on RPI. To verify the efficiency of proposed strategy, the end-to-end performance is evaluated through an error resilient packet video transmission using ITU-T H.263+ codec over a simulated DiffServ network. Results show that the proposed QoS mapping mechanism can exploit the relative DiffServ advantage and result in the persistent service differentiation among DiffServ levels and the enhanced end-to-end video quality with the same pricing constraint