Browsing by Subject "Transient response"

Now showing 1 - 5 of 5

Open Access
Efficient use of closed-form Green's functions for three-dimensional problems involving multilayered media
(IEEE, 1994-06) Aksun, M. Irsadi; Mittra, R.
With the use of casting the spatial domain Green's functions into closed forms approach, it was demonstrated that the computational efficiency of the method of moments (MoM) for the solution of the mixed potential integral equations can be improved significantly for planar microstrip geometries. However, this approach is not effective in the improvement in the computational efficiency achieved for three-dimensional geometries in planar layered media. In this paper, discussed are the difficulties involved in using the spatial domain, closed-form Green's functions in the Method of Moments formulation for three-dimensional geometries and proposed a technique to improve the computational efficiency of the MoM.
Open Access
Kesirli fourier dönüşümünün zaman bölgesinde sonlu farklar yöntemine uygulanması
(IEEE, 2010-04) Sayın, I.; Arıkan F.; Arıkan, Orhan
Bilgisayarların hız ve belleklerinin gelişmesi ile birlikte elektromanyetik problemlerin çözümünde saysal yöntemler sıkça kullanılmaya başlanmış ve bu konuda çok sayda araştırma yapılmıştır. Saysal Elektromanyetik yöntemleri genel olarak zaman ve frekans tabanlı yöntemler olarak sınıflandırılabilir. Zaman tabanlı yöntemler geçici tepkilerin ve geniş bantlı problemlerin incelenmesinde kullanışlı olurken, frekans tabanlı yöntemler durağan hal tepkilerin ve dar bantlı problemlerin incelenmesinde en iyi çözümü vermektedir. Her iki yaklaşımın da avantajlarını ön plana çıkarabilecek bir yöntem geliştirilebileceği düşünülmektedir. Uzayda ve/veya zamanda Kesirli Fourier Dönüşümü uygulanarak bazı durumlarda hesaplama karmaşıklığı azaltılabilir. Kesirli Fourier Dönüşümü, sürekli Fourier Dönüşümünün genelleştirilmiş halidir. Son yıllarda bu konu üzerinde çeşitli çalışmalar yapılmakta ve uygulama alanları genişlemektedir. Genel olarak, sinyal işleme ve gürültü süzme gibi alanlarda kullanılmaktadır. Bu çalmada Kesirli Fourier Dönüşümü, ilk kez Maxwell denklemlerine zaman bölgesinde uygulanmış ve elde edilen diferansiyel denklemler sonlu farklar yaklaşımı ile ayrık hale getirilmiştir. Elde edilen ayrık sonlu fark denklemlerinin çözümü için öneriler sunulmuştur.
Open Access
Long short-term memory for improved transients in neural network adaptive control
(IEEE, 2023-07-03) İnanç, Emirhan; Gürses, Yiğit; Habboush, Abdullah; Yıldız, Yıldıray
In this study, we propose a novel adaptive control architecture, which provides dramatically better performance compared to conventional methods. What makes this architecture unique is the synergistic employment of a traditional, Adaptive Neural Network (ANN) controller and a Long Short-Term Memory (LSTM) network. LSTM structures, unlike the standard feed-forward neural networks, take advantage of the dependencies in an input sequence, which helps predict the evolution of an uncertainty. Through a training method we introduced, the LSTM network learns to compensate for the deficiencies of the ANN controller. This substantially improves the transient response by allowing the controller to quickly react to unexpected events. Through careful simulation studies, we demonstrate that this architecture can improve the estimation accuracy on a diverse set of unseen uncertainties. We also provide an analysis of the contributions of the ANN controller and LSTM network, identifying their individual roles in compensating low and high frequency error dynamics. This analysis provides insight into why and how the LSTM augmentation improves the system’s transient response.
Embargo
On the use of drift correction for electrochemical impedance spectroscopy measurements
(Elsevier, 2023-02-01) Orazem, M.E.; Ulgut, Burak
The effectiveness of drift correction is explored for measurement of electrochemical impedance spectra. Numerical simulations and experimental data for batteries and capacitors are used to show that drift correction cannot generate Kramers–Kronig consistent data for nonstationary systems. Application of drift correction improves, but does not fully recover, the original spectrum that is not corrupted by the drift. Drift correction improved the quality of spectra obtained for stationary systems under galvanostatic modulation, where the change from one frequency to another caused initial transients that corrupted the measurement.
Open Access
Time-varying repetitive control for better transient response and stochastic behaviour
(IET, 2001) Köroğlu, H.; Morgül, Ö.
A stability proof is given for a time-varying repetitive control strategy. It is illustrated by a simulation example that this time varying strategy can be used to improve the transient response and stochastic behaviour of the repetitive control system simultaneously.