Özer, Mahmut | Bal, Abdullah

Article | 2004 | Istanbul University Journal of Electrical and Electronics Engineering4 ( 1 ) , pp.1091 - 1104

In this paper, we investigate dynamics of voltage-gated ionic channels which are of great importance in integrating the information received by neurons. Understanding of dynamical behavior of voltage-gated ionic channels plays a major role for determining underlying mechanism of spike activity and predicting the neuronal behavior. Investigation is carried out based on Hodgkin-Huxley (H-H) mathematical formalism. Ionic channel gate model is discussed briefly. Relaxation phenomenon is studied in the gate variables. Then effects of temperature on dynamics of gate variables are examined. Finally voltage-clamped simulations are carried o . . .ut to determine their dynamic behaviors based on squid giant axon. In this paper, we investigate dynamics of voltage-gated ionic channels which are of great importance in integrating the information received by neurons. Understanding of dynamical behavior of voltage-gated ionic channels plays a major role for determining underlying mechanism of spike activity and predicting the neuronal behavior. Investigation is carried out based on Hodgkin-Huxley (H-H) mathematical formalism. Ionic channel gate model is discussed briefly. Relaxation phenomenon is studied in the gate variables. Then effects of temperature on dynamics of gate variables are examined. Finally voltage-clamped simulations are carried out to determine their dynamic behaviors based on squid giant axon Daha fazlası Daha az

Özer, Mahmut

Proceedings | 2003 | Mathematical and Computational Applications8 ( 1-3 ) , pp.71 - 78

In this study, phase-plane analysis is carried out for a simplified model of Purkinje cell dendrite in terms of voltage-gated ionic channels involved. State variables, nullclines and equilibrium points of the model are determined, and effects of ionic channel conductance and injected current on the shape of nullclines and the equilibrium points are investigated. In this study, phase-plane analysis is carried out for a simplified model of Purkinje cell dendrite in terms of voltage-gated ionic channels involved. State variables, nullclines and equilibrium points of the model are determined, and effects of ionic channel conductance and . . . injected current on the shape of nullclines and the equilibrium points are investigated Daha fazlası Daha az

Erem, Fundagül | İnan, Mehmet | Karakaş Budak, Barçın | Certel, Muharrem

Article | 2020 |

The aim of this study was to purify and characterize the peptidase of Bacillus amyloliquefaciens (Fukumoto) (strain FE-K1) isolated from ropey bread. Peptidases were purified from crude enzyme solution by affinity chromatography with an efficiency of 25 % and a purification coefficient of 1.53. The optimum pH of partially purified peptidase (PPPase) solution was determined as 7.5 and the peptidases retained approximately 90 % of their initial activity in the pH range 7.0-8.5 following incubation at 37°C for 2 h. The optimum temperature for the PPPase was 60°C. The approximate molecular weight of the PPPase was determined as 36 kDa. . . .Inactivation of the PPPase in the presence of O-FEN and EDTA showed them to be metallopeptidases and 5 mM of K+1 and 5 mM of Mn+2 ions increased the enzyme activity by 4 % and 6.15 %, respectively. The presence of Hg+2, Fe+3 and SDS (0.1-1.0 % w/v) caused inactivation whereas the enzyme retained most of its activity in the presence of 0.1-1.0 % (v/v) Triton X-100, Tween 20 and Tween 80 and 1-20 % (v/v) xylene, ethanol, acetone and acetonitrile. Characterization of the PPPase revealed the enzyme as a neutral serine metallopeptidase compatible with some organic solvents and surfactants Daha fazlası Daha az

Erem, Fundagül | İnan, Mehmet | Certel, Muharrem

Article | 2018 |

In this study, it was aimed to optimise the extracellular peptidase production of Bacillus amyloliquefaciens FE-K1, previously isolated from ropy wholemeal bread, by using response surface methodology (RSM) based on central composite design (CCD). The temperature (20-45°C), initial pH of the enzyme production medium (pH 5-9) and inoculation level (1-5%, v/v) were used as the factors for RSM, and the fermentation time was determined for each trial separately. Results showed that the optimum peptidase production occurred at 33.4°C, pH 6.62 and 2.3% inoculation. It was determined that the fermentation time was only 7h, the crude enzyme . . . had a peptidase activity of 49.17U/mL and a specific activity of 504.77U/mg under the optimised conditions Daha fazlası Daha az

Özer, Mahmut

Article | 2012 | Yükseköğretim ve Bilim Dergisi2 ( 1 ) , pp.10 - 13

Son yıllarda dünya genelinde sayıları üç milyonun üzerinde olan uluslararası öğrencileri kendi ülkelerinin yükseköğretim kurumlarına alabilmek için ülkeler kıyasıya rekabet etmektedirler. Uluslararası öğrenciler, artık yükseköğretim sistemleri ve kurumlarının uluslararasılaşma boyutlarının en önemli göstergelerinden birisini oluşturmaktadır. Bu bağlamda, yükseköğretim sistemimiz ve kurumlarımızın bu göstergesinin ne durumda olduğunun tespiti, oldukça büyük bir genişleme yaşayan yükseköğretim sistemimiz açısından büyük önem arz etmektedir. Bu çalışmada, ülkemizdeki uluslararası öğrencilerin durumu ele alınmaktadır There are over thre . . .e million international students worldwide, and in recent years higher education institutions compete with each other in order to receive these students to their institutions. International students are now one of the most important indicator of the internationalization of the higher education systems and institutions. In this context, the detection of the status of this indicator in our higher education system and institutions is of great importance as our higher education system shows a large expansion. This study, discusses the status of international students in our countr Daha fazlası Daha az

Narin, Ali | İşler, Yalçın | Özer, Mahmut

Other | 2014 | Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi16 ( 48 ) , pp.1 - 8

Konjestif kalp yetmezliği (KKY) vücudun ihtiyaç duyduğu miktarda kanın pompalanamaması durumudur. Bu tanıya sahip hastaların ölüm oranı çok yüksek olduğundan erken teşhis önemlidir. Bu amaçla gerçekleştirilen sınıflandırma algoritmalarının performanslarının ölçümü için farklı doğrulama yöntemleri vardır. Bu çalışmada, KKY hastalarının teşhisinde sık kullanılan 5 farklı sınıflandırıcının performans ölçümleri için k-parçalı ve birisi-dışarıda çapraz doğrulama yöntemleri denenmiştir. Her algoritma 100 defa denenerek ortalama başarım ve standart sapmaları kayıt edilmiştir. Sonuç olarak, çapraz doğrulamada kullanılan veri parçası sayısı . . .arttıkça ortalama başarımın arttığı ve başarım değişkenliğinin azaldığı tespit edilmiştir. Congestive heart failure (CHF) occurs when the heart is unable to provide sufficient pump action to maintain blood flow to meet the needs of the body. Early diagnosis is important since the mortality rate of the patients with CHF is very high. There are different validation methods to measure performances of classifier algorithms designed for this purpose. In this study, k-fold and leave-one-out cross validation methods were tested for performance measures of five distinct classifiers in the diagnosis the patients with CHF. Each algorithm was run 100 times and the average and the standard deviation of classifier performances were recorded. As a result, it was observed that average performance was enhanced and variability of performances was decreased when the number of data sections used in the cross validation method was increased Daha fazlası Daha az

Erem, Fundagül | Certel, Muharrem

Article | 2018 |

Bu çalışmada daha önceki bir çalışmada sünmüş ekmeklerden izole edilen 14 adet Bacillus suşunun, 30 °C, 37 °C, 50 °C ve 55 °C’de peptidaz üretme potansiyellerinin belirlenmesinin ardından, peptidaz aktivitesi en yüksek olan iki suş için en uygun enzim üretim besiyeri bileşimi ve koşullarının bir kerede bir faktör yaklaşımı ile optimizasyonu yapılmıştır. Bu amaçla en iyi aktivite değerini sağlayan karbon ve azot kaynağı ile karbon/azot oranı, çalkalama hızı ve ön kültür besiyeri seçimi maliyet unsuru da göz önünde bulundurularak tespit edilmiştir. En iyi karbon ve azot kaynağının sırasıyla glukoz ve maya ekstraktı olduğu saptanmıştır . . .. Ayrıca karbon/azot oranının 1:5, çalkalama hızının 250 rpm olması durumunda ve ön kültür hazırlanması için enzim üretim ortamı ile aynı besiyeri kullanıldığında daha yüksek peptidaz aktivitesi değeri elde edilmiştir Daha fazlası Daha az

Genç, Ayten

Article | 2009 | Turkish Journal of Engineering and Environmental Sciences33 ( 1 ) , pp.73 - 81

The membrane potentials for asymmetric membranes where fixed charges varied linearly with position were evaluated from the numerical solutions of Nernst-Planck flux and Donnan potential equations. The evaluated membrane potentials were compared with the results obtained from the conventional TMS theory where the fixed charge concentration in the membrane was assumed to be uniform. In the comparison, the number of fixed charges was kept constant by defining an average for the fixed charge concentration. The numerical results showed that the membrane potential increased in magnitude when the distributions of fixed charges at the membr . . .ane-solution interfaces were unequal. In addition, the deviation from TMS theory increased more as the charge difference at the interfaces increased. © TÜBİTAK Daha fazlası Daha az

Altan, Aytaç | Köksal, Kerem | Hacıoğlu, Rıfat

Article | 2017 | Karaelmas Fen ve Mühendislik Dergisi7 ( 1 ) , pp.218 - 227

Bu çalışmada, görsel çizgi (rota) takibi için İnsansız Hava Aracı (İHA) üzerinde bulunan 3 eksenli yalpanın dış bozucu etki altında model öngörülü denetimi gerçekleştirilmektedir. İHA ile görsel çizgi takibi için Tanjant Vektör Alan Kılavuz (TVAK) yöntemi kullanılmaktadır. Dış ortam ve kapalı ortamda yapılan testlerde, ön tanımlaması yapılan çizginin görüntü işleme algoritmalarıyla tespiti ve sonrasında TVAK yöntemi kullanılarak rota takip işlemi gerçekleştirilmektedir. İHA’nın alçak ve yüksek irtifa uçuşlarında rota takibi başarım oranları deneysel olarak gözlemlenmektedir. Elde edilen sonuçlar PID denetime sahip yalpadan elde edil . . .en veriler ile karşılaştırılmaktadır. Dış bozucu etki altında TVAK yöntemi ile rota takibi için İHA üzerindeki 3 eksenli yalpanın MPC denetiminde PID ile denetime göre başarılı sonuçlar elde edilmektedir. In this study, Model Predictive Control (MPC) is performed under the external disturbance effect of the 3-axis gimbal on the Unmanned Aerial Vehicle (UAV) for visual line tracking. The Tangent Vector Fields Guide (TVFG) method is used for visual line tracking with UAV. In the tests performed in the outdoor and indoor environments, the pre-defined line is detected with the image processing algorithms and then the line tracking process is performed using the TVFG method. The visual line tracking success rates in the low and high altitude of UAV flight are observed experimentally. The obtained results are compared with data obtained by the gimbal having PID control. The successful results are obtained with MPC control according to PID control of 3 axis gimbal on UAV under external disturbance for visual line tracking using TVFG method Daha fazlası Daha az

Onur, Tuğba Özge | Carlson, Johan E. | Svanström, Erika | Hacıoğlu, Rıfat

Article | 2017 | Erzincan Üniversitesi Fen Bilimleri Enstitüsü Dergisi10 ( 1 ) , pp.138 - 147

Elastik dalgalar, sadece gaz ve sıvılarda değil aynı zamanda katılarda da yayılırlar. Katılar, sıvı ve gazlarda olmayan form elastisitesine sahip olduğundan, katıların elastik özellikleri farklıdır. Bu nedenle, sadece boylamsal dalgalar değil aynı zamanda diğer dalgalar da katılarda yayılabilir. Katı içinde yayılan dalgalar kullanılarak hedefin konumu hakkında bilgi edinilebilir. Bu çalışmada ince düzlemlerde tek transdüktör kullanılarak ultrasonik dalga yayılımının modellenmesi yapılarak, uyarlamalı algoritma ile hedef uzaklığı kestirilmektedir. Elde edilen sonuçlarda, modellenen dalga yayılımında ultrasonik dalganın hızı ile birli . . .kte zaman gecikmesi uyartım noktasının sensöre olan uzaklığı ile ilintili olduğu için, uyarlamalı algoritma ile darbe cevabı başlangıç noktası belirlenerek hedef konumunun tespit edilebildiği görülmektedir. Elastic waves propagate not only in gases and liquids but also in solids. The elastic properties of solids are different since they have form elasticity which liquids and gases don't have. Because of this reason, not only longitudinal waves but also other waves can propagate in solids. Waves propagating in solids can be used to get information about target location. In this paper, modelling of ultrasonic wave propagation in thin plates is investigated by using a single transducer and target distance is estimated with adaptive algorithm. According to the obtained results, it can be seen that target location can be estimated by detecting the starting point of the impulse response with adaptive algorithm since the delay along with the velocity of ultrasound wave in the modelled wave propagation is related to the distance between the excitation point and sensor Daha fazlası Daha az

Onur, Tuğba Özge | Hacıoğlu, Rıfat

Article | 2017 | Turkish Journal of Electrical Engineering and Computer Sciences25 ( 2 ) , pp.939 - 949

We investigated adaptive algorithms for a Hammerstein block structure in which a static nonlinear block and dynamic linear block are cascaded. The approach considered here is to use generalized orthonormal basis functions in a Hammerstein block structure by using xed pole lter banks. We applied the normalized least mean square approach to the developed adaptive algorithm in order to acquire Hammerstein block structure parameters. Performance comparison of the proposed approach was investigated considering convergence speed and parametric complexity for acoustic echo cancellation application. The results indicated that in the develop . . .ed algorithm along with appropriate selection of xed poles, the algorithm convergences faster and less parametric complexity is provided when compared to direct adaptive Hammerstein algorithms with IIR and FIR linear blocks. We investigated adaptive algorithms for a Hammerstein block structure in which a static nonlinear block and dynamic linear block are cascaded. The approach considered here is to use generalized orthonormal basis functions in a Hammerstein block structure by using xed pole lter banks. We applied the normalized least mean square approach to the developed adaptive algorithm in order to acquire Hammerstein block structure parameters. Performance comparison of the proposed approach was investigated considering convergence speed and parametric complexity for acoustic echo cancellation application. The results indicated that in the developed algorithm along with appropriate selection of xed poles, the algorithm convergences faster and less parametric complexity is provided when compared to direct adaptive Hammerstein algorithms with IIR and FIR linear blocks Daha fazlası Daha az

Altan, Aytaç | Hacıoğlu, Rıfat

Proceedings | 2014 | 2014 22ND SIGNAL PROCESSING AND COMMUNICATIONS APPLICATIONS CONFERENCE (SIU) , pp.1686 - 1689

In this study, unmanned vehicles used for target tracking camera RRP (revolute revolute prismatic) joint structure with a three-jointed robot arm with the position, velocity and acceleration control is made. In order to be able to follow the specified trajectory, the system used in the control of the robot arm with joint structure RRP target tracking model based on changing according to the structure proposed by the MPC is implemented. Also the PID (Proportional Integral Dervative) is provided with control comparison was made. MATLAB/Simulink simulations performed unmanned vehicles used for target tracking in robotic camera control . . .with the system were investigated in the MPC Daha fazlası Daha az