Performability modelling of homogeneous and heterogeneous multi-server systems with breakdowns and repairs
Başlık çevirisi mevcut değil.
- Tez No: 401606
- Danışmanlar: PROF. RAM CHAKKA
- Tez Türü: Doktora
- Konular: Bilgisayar Mühendisliği Bilimleri-Bilgisayar ve Kontrol, Computer Engineering and Computer Science and Control
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2007
- Dil: İngilizce
- Üniversite: Mıddlesex Unıversıty
- Enstitü: Yurtdışı Enstitü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: Belirtilmemiş.
Özet
Özet yok.
Özet (Çeviri)
This thesis presents analytical modelling of homogeneous multi-server systems with recon¯g- uration and rebooting delays, heterogeneous multi-server systems with one main and several identical servers, and farm paradigm multi-server systems. This thesis also includes a number of other research works such as, fast performability evaluation models of open networks of nodes with repairs and ¯nite queuing capacities, multi-server systems with deferred repairs, and two stage tandem networks with failures, repairs and multiple servers at the second stage. Applications of these for the popular Beowulf cluster systems and memory servers are also accomplished. Existing techniques used in performance evaluation of multi-server systems are investigated and analysed in detail. Pure performance modelling techniques, pure availability models, and performability models are also considered. First, the existing approaches for pure per- formance modelling are critically analysed with the discussions on merits and demerits. Then relevant terminology is de¯ned and explained. Since the pure performance models tend to be too optimistic and pure availability models are too conservative, performability models are used for the evaluation of multi-server systems. Fault-tolerant multi-server systems can continue service in case of certain failures. If failure does not occur at a critical point (such as breakdown of the head processor of a farm paradigm system) the system continues serving in a degraded mode of operation. In such systems, recon¯guration and/or rebooting delays are expected while a processor is being mapped out from the system. These delay stages are also taken into account in addition to failures and repairs, in the exact performability models that are developed. Two dimensional Markov state space representations of the sys- tems are used for performability modelling. Following the critical analysis of the existing solution techniques, the Spectral Expansion method is chosen for the solution of the models developed. In this work, open queuing networks are also considered. To evaluate their performability, existing modelling approaches are expanded and validated by simulations, for performability analysis of multistage open networks with ¯nite queuing capacities. The performances of two extended modelling approaches are compared in terms of accuracy for open networks with various queuing capacities. Deferred repair strategies are becoming popular because of the cost reductions they can provide. E®ects of using deferred repairs are analysed and performability models are pro- vided for homogeneous multi-server systems and highly available farm paradigm multi-server systems.Since one of the random variables is used to represent the number of jobs in one of the queues, analytical models for performance evaluation of two stage tandem networks su®er because of numerical cumbersomeness. Existing approaches for modelling these systems are actually pure performance models since breakdowns and repairs cannot be considered. One way of modelling these systems can be to divide one of the random variables to present both the operative and non-operative states of the server in one dimension. However, this will give rise to state explosion problem severely limiting the maximum queue capacity that can be handled. In order to overcome this problem a new approach is presented for modelling two stage tandem networks in three dimensions. An approximate solution is presented to solve such a system. This approach manifests itself as a novel contribution for alleviating the state space explosion problem for large and/or complex systems. When two state tandem networks with feedback are modelled using this approach, the operative states can be handled independently and this makes it possible to consider multiple operative states at the second stage. The analytical models presented can be used with various parameters and they are extendible to consider systems with similar architectures. The developed three dimensional approach is capable to handle two stage tandem networks with various characteristics for performability measures. All the approaches presented give accurate results. Numerical solutions are presented for all models developed. In case the solution presented is not exact, simulations are performed to validate the accuracy of the results obtained.
Benzer Tezler
- PEM tipi yakıt hücresi reaktant akış kanallarının üç boyutlu modellenmesi
Three dimensional modeling of PEM type fuel cell reaktant flow channels
İSMAİL ÖZGÜN
Yüksek Lisans
Türkçe
2021
Makine MühendisliğiSakarya Uygulamalı Bilimler ÜniversitesiMakine Mühendisliği Ana Bilim Dalı
DR. ÖĞR. ÜYESİ HÜSEYİN KAHRAMAN
- Developing a methodology for the design and optimization of the pressure-swirl atomizers
Başlık çevirisi yok
OZAN EKİN NURAL
Doktora
İngilizce
2023
Makine MühendisliğiÖzyeğin ÜniversitesiMakine Mühendisliği Ana Bilim Dalı
DOÇ. DR. ÖZGÜR ERTUNÇ
- An investigation into the effects of different parameters on high-resolution geoid modeling accuracy in the context of height system modernization
Yükseklik sistemi modernizasyonu bakımından farklı parametrelerin yüksek çözünürlüklü geoit modelleme doğruluğu üzerindeki etkilerinin incelenmesi
ONUR KARACA
Doktora
İngilizce
2024
Jeodezi ve Fotogrametriİstanbul Teknik ÜniversitesiGeomatik Mühendisliği Ana Bilim Dalı
PROF. DR. BİHTER EROL
- İnsansı robotlarda yürüme
Humanoid walking
SABRİ YILMAZ
Yüksek Lisans
Türkçe
2013
Bilgisayar Mühendisliği Bilimleri-Bilgisayar ve Kontrolİstanbul Teknik ÜniversitesiKontrol ve Otomasyon Mühendisliği Ana Bilim Dalı
PROF. DR. METİN GÖKAŞAN
- Mühimmat depo yeri seçimi ve dağıtım ağı tasarımı problemi: karışık tam sayılı lineer programlama ve uygulaması
The ammunition depot location selection and distribution network design problem: A mixed integer linear programming model and its application
MUSTAFA ACAR
Yüksek Lisans
Türkçe
2018
Endüstri ve Endüstri MühendisliğiBalıkesir ÜniversitesiEndüstri Mühendisliği Ana Bilim Dalı
DR. ÖĞR. ÜYESİ İBRAHİM KÜÇÜKKOÇ