Browsing by Subject "Processing elements"
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Item Open Access Analysis of design parameters in SIL-4 safety-critical computer(IEEE, 2017-01) Ahangari, Hamzeh; Özkök, Y. I.; Yıldırım, A.; Say, F.; Atik, Funda; Öztürk, ÖzcanNowadays, Safety-critical computers are extensively used in may civil domains like transportation including railways, avionics and automotive. We noticed that in design of some previous works, some critical safety design parameters like failure diagnostic coverage (DC) or common cause failure (CCF) ratio have not been seriously taken into account. Moreover, in some cases safety has not been compared with standard safety levels (IEC-61508 SIL1-SIL4) or even have not met them. Most often, it is not very clear that which part of the system is the Achilles' heel and how design can be improved to reach standard safety levels. Motivated by such design ambiguities, we aim to study the effect of various design parameters on safety in some prevalent safety configurations: 1oo2 and 2oo3. 1oo1 is also used as a reference. By employing Markov modeling, sensitivity of safety to each of the following critical design parameters is analyzed: failure rate of processing element, failure diagnostics coverage, common cause failures and repair rates. This study gives a deeper sense regarding influence of variation in design parameters over safety. Consequently, to meet appropriate safety integrity level, instead of improving some system parts blindly, it will be possible to make an informed decision on more relevant parameters. © 2017 IEEE.Item Open Access Communication efficient channel estimation over distributed networks(IEEE, 2014) Sayın, Muhammed O.; Vanlı, N. Denizcan; Göze, T.; Kozat, Süleyman SerdarWe study diffusion based channel estimation in distributed architectures suitable for various communication applications such as cognitive radios. Although the demand for distributed processing is steadily growing, these architectures require a substantial amount of communication among their nodes (or processing elements) causing significant energy consumption and increase in carbon footprint. Due to growing awareness of telecommunication industry's impact on the environment, the need to mitigate this problem is indisputable. To this end, we introduce algorithms significantly reducing the communication load between distributed nodes, which is the main cause in energy consumption, while providing outstanding performance. In this framework, after each node produces its local estimate of the communication channel, a single bit or a couple of bits of information is generated using certain random projections. This newly generated data is diffused and then used in neighboring nodes to recover the original full information, i.e., the channel estimate of the desired communication channel. We provide the complete state-space description of these algorithms and demonstrate the substantial gains through our experiments.Item Open Access Distributed adaptive filtering with reduced communication load(IEEE, 2016) Utlu, İhsan; Kozat, Süleyman SerdarWe propose novel algorithms for distributed processing in applications constrained by available communication resources, using diffusion strategies that achieve up to three orders-of-magnitude reduction in communication load on the network, while delivering equal performance with respect to the state of the art. After computation of local estimates, the information is diffused among processing elements (or nodes) non-uniformly in time by conditioning the information transfer on level-crossings of the diffused parameter, resulting in a greatly reduced communication requirement. We provide the mean stability analysis of our algorithms, and illustrate the gain in communication efficiency compared to other reducedcommunication distributed estimation schemes.