Wireless model-based predictive networked control system over cooperative wireless network

Owing to their distributed architecture, networked control systems (NCSs) are proven to be feasible in scenarios where a spatially distributed feedback control system is required. Traditionally, such NCSs operate over real-time wired networks. Recently, in order to achieve the utmost flexibility, scalability, ease of deployment, and maintainability, wireless networks such as IEEE 802.11 wireless local area networks (LANs) are being preferred over dedicated wired networks. However, conventional NCSs with event-triggered controllers and actuators cannot operate over such general purpose wireless networks since the stability of the system is compromised due to unbounded delays and unpredictable packet losses that are typical in the wireless medium. Approaching the wireless networked control problem from two perspectives, this work introduces a practical wireless NCS and an implementation of a cooperative medium access control protocol that work jointly to achieve decent control under severe impairments, such as unbounded delay, bursts of packet loss and ambient wireless traffic. The proposed system is evaluated on a dedicated test platform under numerous scenarios and significant performance gains are observed, making cooperative communications a strong candidate for improving the reliability of industrial wireless networks

Evaluation of a client-server real-time database system

A real-time database system (RTDBS) can be defined as a database system where transactions are associated with real-time constraints. In this paper, we investigate various performance issues in a RTDBS constructed on a client-server system architecture. In a client-server database management system the whole database is stored on the server disks, and copies of database items can be cached in the client memories. We provide a detailed simulation model of a client-server RTDBS, and present the initial results of a performance work that evaluates the effects of various workload parameters and design alternatives. Index Terms - Real-time database systems, client-server architecture, transaction scheduling, timing constraints

International competitiveness power and human development of countries

Human development should be the ultimate objective of human activity and its aim should be healthier, longer, and fuller lives. It is expected that if the competitiveness of a country is suitably managed, human welfare will be enhanced as a consequence. The research described here seeks to explore the relationship between the competitiveness of a country and its use for human development. For this purpose, 45 countries were evaluated using data envelopment analysis, where the global competitiveness indicators are taken as input variables and the human development index indicators as output variables. A detailed analysis is also conducted for the emerging economies

A study on technology management process: the parts and components suppliers in the Turkish automotive industry

This paper summarizes part of an empirical study on technology management process in the Turkish automotive parts and components industry. In this study, technology management practices in the Turkish automotive parts and components suppliers' sector are described and evaluated. Practices, techniques, and approaches are proposed to improve the level of technology management so as to turn technology into a competitive weapon. The investigation is organized within the framework of a process model for technology management that consists of technology identification, selection, acquisition, exploitation, protection, and abandonment. A comprehensive questionnaire addressing all phases of this process is developed and the results of 21 companies are presented

The role of location of traffic control in internetwork gateways

Summary form only given. An evaluation of window-based gateway-to-gateway-level congestion control in an interconnected network environment is reported. Two dynamic control algorithms proposed by the author are intended to operate the system below the critical internetwork load that gives rise to congestion at gateways and connected networks. In one of the algorithms, source gateways regulate the traffic flow, whereas in the other, destination gateways provide the control. The algorithms provide further control to static window protocol by adjusting the window size in accordance with the availability of network resources at the destination. A comparison of the two algorithms has shown that controlling the internetwork messages at the destination gateway produces better performance results than control at the source gateway

Dynamic congestion control in interconnected computer networks

In interconnected networks, the performance of a network is affected heavily by the traffic transmitted from other networks. A network may become subject to congestion when the internetwork traffic increases rapidly. It is well known that congestion gives rise to a degradation in network performance. In this paper, we evaluate window-based congestion control mechanism in an internetwork environment. We also propose and study two dynamic window congestion control algorithms. These algorithms provide further control to window mechanism by adjusting the window size in accordance with the availability of the network resources at the destination. Dynamic algorithms are evaluated as compared with fixed window control by means of computer simulation. NW:Netvork GN:G.leWay Figur

Association rules for supporting hoarding in mobile computing environments

One of the features that a mobile computer should provide is disconnected operation which is performed by hoarding. The process of hoarding can be described as loading the data items needed in the future to the client cache prior to disconnection. Automated hoarding is the process of predicting the hoard set without any user intervention. In this paper, we describe an application independent and generic technique for determining what should be hoarded prior to disconnection. Our method utilizes association rules that are extracted by data mining techniques for determining the set of items that should be hoarded to a mobile computer prior to disconnection. The proposed method was implemented and tested on synthetic data to estimate its effectiveness. Performance experiments determined that the proposed rule-based methods are effective in improving the system performance in terms of the cache hit ratio of mobile clients especially for small cache sizes

Teknoloji yönetimi süreci üzerine bir çalışma: Türk otomotiv endüstrisi yan sanayii

Türk otomotiv yan sanayiinde teknoloji yönetimi süreci üzerine ampirik bir çalışmanın özeti olan bu makalede, Türk otomotiv yan sanayiindeki teknoloji yönetimi uygulamaları ele alınmış ve değerlendirilmiştir. Teknoloji yönetimi seviyesini yükseltmek için sunulan uygulamaların, teknik ve yaklaşımların temel amacı, teknolojiyi rekabetçi bir silah olarak kullanabilmektir. Bu araştırma, teknoloji yönetiminde süreç modeli çerçevesinde organize edilmiştir. Teknoloji yönetiminde süreç modeli; teknoloji belirlenmesi, seçimi, edinimi, kullanımı, korunumu ve sonlandırılmasını içermektedir. Süreci bütün kısımları ile inceleyen ve 21 şirketi kapsayan bir anket çalışması yapılmış ve sonuçları burada sunulmuştur