Sakarya University Journal of Science

6-11

Authors: Deniz iKiZ, Mustafa GÜLFEN, Ali Osman AYDIN

The optimum leaching conditions or primary chalcopyrite ore from Artvin-Murgul region in Turkey have been examined in hypochlorite solution. The effects of various parameters as initial pH, hypochlorite concentration, stirring speed, solid/ liquid ratio and temperature to the copper dissolution from chalcopyrite were investigated. lt was found that chalcopyrite reacted with chlorine generated fron1 hypochlorite in acidic pH values. PH effecctively decreased during the dissolution. It was detern1incd th at the optin1un1 leac hing conditions were initial pH of 5-6 , hypochlorite concentration of0.2 N for 4 g/L so lid/liquid rati o. 600 rpm stirring speed and it was seen that sulphate forn1at ion was over 50%.

18-24

Authors: Muzaffer ASLAN, Hanifi GÜLDEMİR

Bu calışmada yükseltici tip bir da-da dönüştürücünün sürekli durum analizi ile dinamik davranışı detaylı olarak incelenmiştir. Kayma mod kontrol temel prensibi verilip, yükseltici tip da-da dönüştürücünün kayma mod kontrolü icin ifadeler türetilmiştir. Matlab/Simulink paket programı kullanılarak simulasyonu yapılıp simulasyon sonucları verilmiştir.Simulasyon. degi$ik yi.ik ve <;tkt$ gerilin1leri ic;in yaptltnt$, giri ~ gcri lin1indek i degi$iklikler ile yi.ikteki degi$in1lerin c; tki$ gerilin1i Li ze rine etkileri incelennli$ olup, tasarlanan kontrol siste tninin bu degi$in1lere kar$1 dayantklt oldugu sin1ulasyon so nuc; lanndan gori.ilnlU $tU r. YUkse ltici tip da-da donli~tlirlicli n1odeli hen1 elde ed ilen dinatnik denklen1ler kullantlarak olu$turuln1U$ hetn de Matlab/Sitnpowersystenl ara<; kut usu i<;erisindeki devre elen1anlan k u 11 an t I a r a k g er<; c k I e ~ t i r i ltn i ~ t i r.

32-40

Authors: Serkan KARATAŞ, Naim ÇAĞMAN

Fuzzy ölçüm kavramı 1974 'te Sugeno tarafından verilmiştir. Fuzzy ölçüm metotları belirsizlikleri modellemekte kullanılmaktadır. Bu çalışmada, literatürdeki fuzzy ölçüm metotlarının bir sınıflandırmasını sunulmuş ve bunların arasındaki bazı önemli ilişkileri incelenmiştir.

44-50

Authors: Adem KARAHOCA , Talat FIRLAR

Mobile telecommunication industry is in a radical development process in todays world. In this proces , an increase the services which are based on data for mobile users are more ant icipated than the voice communication syster Effective security solutions must be provided as soon as possible to continue the success of this industry. A sec environment should be obtained for the mobile network systems. application providers and subscriptions in order allow them to perform operations. According to the Nokia, there are approxitnately 300 third-generation mobile networks and each of them has at least l000 access nodes with one billion subsc ribers in the n1obile telecotnn1uni cation industry. ~rh cse \\'ide area net\vo rks going to be IP based systen1s so secure environn1ents n1ust be established which includes the functions of verificat i warnin o and tracinn. b ~ In this article, sec urity so lutions of second and third generation n1obile technologies arc general!) ex plained for n1oc groups. Also the vv ritcr dea ls \Vith the security probletn s and so lut ions in the parallel of the grLat c'\pcricnces \ V h \VC rc ga ined while \VO rk ing in a GSM operator in Turkey.