Browsing by Subject "Gibbs free energy"

Now showing 1 - 4 of 4

Open Access
Estimation of depth fields suitable for video compression based on 3-D structure and motion of objects
(Institute of Electrical and Electronics Engineers, 1998-06) Alatan, A. A.; Onural, L.
Intensity prediction along motion trajectories removes temporal redundancy considerably in video compression algorithms. In three-dimensional (3-D) object-based video coding, both 3-D motion and depth values are required for temporal prediction. The required 3-D motion parameters for each object are found by the correspondence-based E-matrix method. The estimation of the correspondences - two-dimensional (2-D) motion field - between the frames and segmentation of the scene into objects are achieved simultaneously by minimizing a Gibbs energy. The depth field is estimated by jointly minimizing a defined distortion and bitrate criterion using the 3-D motion parameters. The resulting depth field is efficient in the rate-distortion sense. Bit-rate values corresponding to the lossless encoding of the resultant depth fields are obtained using predictive coding; prediction errors are encoded by a Lempel-Ziv algorithm. The results are satisfactory for real-life video scenes.
Open Access
Gibbs free energy assisted passivation layers
(SPIE, 2016) Salihoğlu, Ömer; Tansel, T.; Hoştut, M.; Ergun, Y.; Aydınlı, Atilla
Reduction of surface leakage is a major challenge in most photodetectors that requires the elimination of surface oxides on etched mesas during passivation. Engineering the passivation requires close attention to chemical reactions that take place at the interface during the process. In particular, removal of surface oxides may be controlled via Gibbs reactivity. We have compared electrical performance of type-II superlattice photodetectors, designed for MWIR operation, passivated by different passivation techniques. We have used ALD deposited Al2O3, HfO2, TiO2, ZnO, PECVD deposited SiO2, Si3N4 and sulphur containing octadecanethiol (ODT) selfassembled monolayers (SAM) passivation layers on InAs/GaSb p-i-n superlattice photodetectors with cutoff wavelength at 5.1 μm. In this work, we have compared the result of different passivation techniques which are done under same conditions, same epitaxial structure and same fabrication processes. We have found that ALD deposited passivation is directly related to the Gibbs free energy of the passivation material. Gibbs free energies of the passivation layer can directly be compared with native surface oxides to check the effectiveness of the passivation layer before the experimental study.
Open Access
Object based 3-D motion and structure estimation
(IEEE, 1996) Alatan, A. Aydın; Onural, Levent
Motion analysis is the most crucial part of object-based coding. A motion in 3-D environment can be analyzed better by using a 3-D motion model compared to its 2-D counterpart and hence may improve coding efficiency. Gibbs formulated joint segmentation and estimation of 2-D motion not only improves performance, but also generates robust point correspondences which are necessary for linear 3-D motion estimation algorithms. Estimated 3-D motion parameters are used to find the structure of the previously segmented objects by minimizing another Gibbs energy. Such an approach achieves error immunity compared to linear algorithms. Experimental results are promising and hence the proposed motion and structure analysis method is a candidate to be used in object-based (or even knowledge-based) video coding schemes.
Open Access
Sorption studies of Cs+ and Ba2+ cations on magnesite
(Elsevier, 1998-05-11) Shahwan, T.; Süzer, Şefik; Erten, H. N.
The adsorption behavior of Cs+ and Ba2+ cations on magnesite has been studied as a function of time, cation concentration and temperature, utilizing both the radiotracer method and X-ray photoelectron spectroscopy (XPS). Saturation was approached in about I day for both cations. The sorption data were found to follow Freundlich type isotherms. Sorption of both Cs+ and Ba2+ cations were found to be exothermic in nature with ΔH0 (kJ/mol) of -37, -13 and ΔS0 (kJ/mol·K) of -0.09, -0.009, respectively. Negative ΔG0 values were obtained for both cations, indicating the spontaneity of their sorption on magnesite. The magnitude of ΔG0 suggest that ion exchange is the dominating sorption mechanism. The adsorption behavior of Cs+ and Ba2+ cations on magnesite has been studied as a function of time, cation concentration and temperature, utilizing both the radiotracer method and X-ray photoelectron spectroscopy (XPS). Saturation was approached in about 1 day for both cations. The sorption data were found to follow Freundlich type isotherms. Sorption of both Cs+ and Ba2+ cations were found to be exothermic in nature with ΔH0 (kJ/mol) of -37, -13 and ΔS0 (kJ/mol·K) of -0.09, -0.009, respectively. Negative ΔG0 values were obtained for both cations, indicating the spontaneity of their sorption on magnesite. The magnitude of ΔG0 suggest that ion exchange is the dominating sorption mechanism.