DCS系统在鼓风机控制中的应用

本文主要介绍了DCS控制系统在莱钢焦化厂鼓风机改造中的应用,重点介绍了鼓风机改造的技术要点,并对鼓风机改造前的现状和改造后的效果进行了简要阐述。     

Admission Control Algorithms for Revenue Optimization with QoS Guarantees in Mobile Wireless Networks

We propose and analyze call admission control algorithms integrated with pricing for revenue optimization with QoS guarantees to serve multiple service classes in mobile wireless networks. Traditional admission control algorithms make acceptance decisions for new and handoff calls to satisfy certain QoS constraints such as the dropping probability of handoff calls and the blocking probability of new calls being lower than a pre-specified threshold. We analyze a class of partitioning and threshold-based admission control algorithms that make acceptance/rejection decisions not only to satisfy QoS requirements but also to optimize the revenue of the system by taking prices and arrival/departure information of service calls into account. We show that for a “charge-by-time” pricing scheme, there exist optimal resource allocation settings under which the partitioning and threshold-based admission control algorithms would produce the maximum revenue obtainable by the system without sacrificing QoS requirements. Further, we develop a new hybrid admission control algorithm which outperforms both partitioning and threshold-based admission control algorithms over a wide range of input parameters characterizing the operating environment and service workload conditions. Methods for utilizing of the analysis results for realtime admission control for revenue optimization with QoS guarantees are described with numerical data given to demonstrate the applicability.     

Dynamic utility and price based radio resource management for rate adaptive traffic

This paper explores analytical Radio Resource Management models where the relationship between users and services is mapped through utility functions. Compared to other applications of these models to networking, we focus in particular on specific aspects of multimedia systems with adaptive traffic, and propose a novel framework for describing and investigating dynamic allocation of resources in wireless networks. In doing so, we also consider economic aspects, such as the financial needs of the provider and the users’ reaction to prices. As an example of how our analytical tool can be used, in this paper we compare different classes of RRM strategies, e.g., Best Effort vs. Guaranteed Performance, for which we explore the relationships between Radio Resource Allocation, pricing, provider’s revenue, network capacity and users’ satisfaction. Finally, we present a discussion about Economic Admission Control, which can be applied in Best Effort scenarios to further improve the performance. Part of this work has been presented at the conference ACM/IEEE MSWiM 2004, Venice (Italy). Leonardo Badia received a Laurea degree (with honors) in electrical engineering and a Ph.D. in information engineering from the University of Ferrara, Italy, in 2000 and 2004, respectively. He was a Research Fellow at the University of Ferrara from 2001 to 2006. During these years, he also had collaborations with the University of Padova, Italy, and Wireless@KTH, Royal Institute of Technology, Stockholm, Sweden. In 2006, he joined the “Institutions Markets Technologies” (IMT) Institute for Advanced Studies, Lucca, Italy, where he is currently a Research Fellow. His research interests include wireless ad hoc and mesh networks, analysis of transmission protocols, optimization tools and economic models applied to radio resource management. Michele Zorzi received a Laurea degree and a Ph.D. in electrical engineering from the University of Padova in 1990 and 1994, respectively. During academic year 1992–1993, he was on leave at UCSD, attending graduate courses and doing research on multiple access in mobile radio networks. In 1993 he joined the faculty of the Dipartimento di Elettronica e Informazione, Politecnico di Milano, Italy. After spending three years with the Center for Wireless Communications at UCSD, in 1998 he joined the School of Engineering of the University of Ferrara, Italy, where he became a professor in 2000. Since November 2003 he has been on the faculty at the Information Engineering Department of the University of Padova. His present research interests include performance evaluation in mobile communications systems, random access in mobile radio networks, ad hoc and sensor networks, energy constrained communications protocols, and broadband wireless access. He was Editor-In-Chief of IEEE Wireless Communications, 2003–2005, and currently serves on the Editorial Boards of IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, Wiley’s Journal of Wireless Communications and Mobile Computing, and ACM/URSI/Kluwer Journal of Wireless Networks, and on the Steering Committee of the IEEE Transactions on Mobile Computing. He has also been a Guest Editor of special issues in IEEE Personal Communications (Energy Management in Personal Communications Systems) and IEEE Journal on Selected Areas in Communications (Multimedia Network Radios).     

质量保证策略下服务商的质量缺陷补偿决策分析

随着竞争的日趋激烈,越来越多的服务商采用质量保证策略作为竞争手段以吸引顾客,然而现有研究缺乏对该策略下的质量缺陷补偿问题的深入分析。鉴于此,本文系统地分析了质量保证策略下服务商的质量缺陷补偿问题:首先分析了当服务价格外生时,服务商的最优质量缺陷补偿决策;然后分别探讨在服务价格内生变化和服务供给变动的影响下,服务商的最优质量缺陷补偿;最后,通过数值分析,探寻在服务价格和服务供给的双重变动影响下,服务商的最优质量缺陷补偿。本文拓展了服务质量的研究,对于指导服务型企业如何制定质量缺陷补偿具有较强的实践启示意义。     

Ensuring strong data guarantees in highly mobile ad hoc networks via quorum systems

Ensuring the consistency and the availability of replicated data in highly mobile ad hoc networks is a challenging task because of the lack of a backbone infrastructure. Previous work provides strong data guarantees by limiting the motion and the speed of the mobile nodes during the entire system lifetime, and by relying on assumptions that are not realistic for most mobile applications. We provide a small set of mobility constraints that are sufficient to ensure strong data guarantees and that can be applied when nodes move along unknown paths and speed, and are sparsely distributed.

In the second part of the paper, we analyze the problem of conserving energy while ensuring strong data guarantees, using quorum system techniques. We devise a condition necessary for a quorum system to guarantee data consistency and data availability under our mobility model. This condition shows the unsuitability of previous quorum systems and is the basis for a novel class of quorum systems suitable for highly mobile networks, called mobile dissemination quorum (MDQ) systems. We also show a MDQ system that is provably optimal in terms of communication cost by proposing an efficient implementation of a read/write atomic shared memory.

The suitability of our mobility model and MDQ systems is validated through simulations using the random waypoint model and the restricted random waypoint on a city section. Finally, we apply our results to assist routing and coordinate the low duty cycle of mobile nodes while maintaining network connectivity.     

输入排队结构交换机分组调度研究

以决定分组调度算法的交换结构为基础,从协调,减少和隔离输入排队交换结构中输入输出竞争裁决冲突的角度,分别讨论了VOQ,CIOQ,CICQ结构中的分组调度问题,并以当前最新的调度算法为例加以说明,进行了定性分析和定量对比,指出了具体有待研究的问题。随后讨论了最近才开始研究的光电混合结构中的分组调度问题。最后从交换结构和算法两个方面探讨了今后的研究方向和发展趋势。     

A Time-Slotted-CDMA Architecture and Adaptive Resource Allocation Method for Connections with Diverse QoS Guarantees

We consider a time-slotted W-CDMA system for mobile stations which are connected to the wired internet. We first present an architecture for such a system that is based on a request-permission protocol incorporating power control for Best Effort transmissions on the uplink. The requesting mobiles are permitted to transmit in the next time slot with a specified power according to a schedule computed by the Base Station. To devise this scheduling method, we formulate a globally optimizing integer program that maximizes the total weighted sum of all best-effort transmissions in the entire system, keeping in view the diverse target Bit Error Rates for each one. This problem is analysed and decomposed into sub-problems that can be solved locally by each Base Station. We devise two fast heuristics to solve the Base Station's sub-problem, so that the new schedule for each successive slot can be re-computed by each Base Station in a practical time-frame. We show that one heuristic is good enough to produce optimal solutions to the sub-problem in special cases. The method is further enhanced to take account of bandwidth and delay guarantees for other connections. It is also modified to ensure fairness for best-effort code channels suffering from persistent location-dependent errors. Finally, we show that a very similar approach can be used by the Base Station for scheduling on the downlink also, leading to a unified approach to scheduling in both directions. The efficacy of the uplink method is briefly demonstrated by simulations comparing the two variants with each other, and demonstrating that one achieves a consistently higher throughput than the other.     

An adaptive AQM to provide delay guarantees for differentiated services

RIO（RED with IN and OUT） is the primary queue management mechanism proposed for assured forwarding in the DiffServ （Differentiated Service） framework. Although RIO can generally provide bandwidth guarantees, its queuing delay is sensitive to the traffic load. This paper presents a qualitative explanation for its origin. As a solution, an Adaptive RIO for Delay （ARIO-D） is proposed to provide guaranteed delay for multimedia traffic. Simulation results show that by trading loss for delay, ARIO-D can effectively improve the robustness of RIO under different and dynamic traffic, and provide stable and differentiated performance of queuing delay without any degradation in performance of throughput.     

Establishing delivery guarantee policies

Delivery reliability has emerged as a key competitive factor in a variety of service and manufacturing industries. Thus, many firms are adopting the use of delivery-time guarantees as part of their market positioning strategy. This research generalizes existing blanket delivery-time guarantee models on several fronts—by drawing on concepts from other fields and by relaxing simplifying assumptions—to provide a comprehensive and practical model. Some analytic results are provided, and numeric experimentation is conducted to provide further insight into the problem. The effects of service improvements, process improvements, and system congestion are analyzed. The results indicate that pricing policies are less critical than previously thought when the payment made for late delivery is included as part of the delivery-time guarantee policy.     

Providing deterministic packet delays and packet losses in multimedia wireless networks

‘Anytime, anywhere’ communication, information access and processing are much cherished in modern societies because of their ability to bring flexibility, freedom and increased efficiency to individuals and organizations. Wireless communications, by providing ubiquitous and tetherless network connectivity to mobile users, are therefore bound to play a major role in the advancement of our society. Although initial proposals and implementations of wireless communications are generally focused on near‐term voice and electronic messaging applications, it is recognized that future wireless communications will have to evolve towards supporting a wider range of applications, including voice, video, data, images and connections to wired networks. This implies that future wireless networks must provide quality‐of‐service (QoS) guarantees to various multimedia applications in a wireless environment. Typical traffic in multimedia applications can be classified as either Constant‐Bit‐Rate (CBR) traffic or Variable‐Bit‐Rate (VBR) traffic. In particular, scheduling the transmission of VBR multimedia traffic streams in a wireless environment is very challenging and is still an open problem. In general, there are two ways to guarantee the QoS of VBR multimedia streams, either deterministically or statistically. In particular, most connection admission control (CAC) algorithms and medium access control (MAC) protocols that have been proposed for multimedia wireless networks only provide statistical, or soft, QoS guarantees. In this paper, we consider deterministic QoS guarantees in multimedia wireless networks. We propose a method for constructing a packet‐dropping mechanism that is based on a mathematical framework that determines how many packets can be dropped while the required QoS can still be preserved. This is achieved by employing: (1) An accurate traffic characterization of the VBR multimedia traffic streams; (2) A traffic regulator that can provide bounded packet loss and (3) A traffic scheduler that can provide bounded packet delay. The combination of traffic characterization, regulation and scheduling can provide bounded loss and delay deterministically. This is a distinction from traditional deterministic QoS schemes in which a 0% packet loss are always assumed with deterministically bounding the delay. We performed a set of performance evaluation experiments. The results will demonstrate that our proposed QoS guarantee schemes can significantly support more connections than a system, which does not allow any loss, at the same required QoS. Moreover, from our evaluation experiments, we found that the proposed algorithms are able to out‐perform scheduling algorithms adopted in state‐of‐the‐art wireless MAC protocols, for example Mobile Access Scheme Based on Contention and Reservation for ATM (MASCARA) when the worst‐case traffic is being considered. Copyright © 2002 John Wiley & Sons, Ltd.