iosr-JEEE   Volume-4 ~ Issue-1

Abstract: GaN/InGaN heterostructure contains a unique property of piezoelectric polarization charges at the interface due to different thermal expansion coefficients. In this paper, we report a simple mathematical model for Ga-face GaN/InGaN heterostructure solar cell. The results obtained from the given model indicates that the piezoelectric polarization charges at the interface of Ga-face GaN/InGaN heterostructure improves the efficiency of a single GaN/InGaN heterostructure photovoltaic solar cell in comparison to the non-polar solar cells by 45% for AM 1.5. This structure can also provide a fundamental solar cell unit for developing very high efficiency MQW solar cell and a MJ solar cell using Ga-face GaN/InGaN structure.
Keywords -GaN/InGaN hetero-structure, Multi-Quantum-Well, Multi-Junction solar cell, Piezoelectric polarization

[1] MMehta,OJan,CHonsbergBJampana,IFerguson,ADoolittle,Modifying PC1D to model spontaneous and piezoelectric polarization in III-V nitride solar cell, 22nd European Photovoltaic Solar Energy Conference, 3-7 September, Milan Italy (2007) 409-413.
[2] O.Jani,C.Honsberg,Y.Huang,J.O.Song,I.Ferguson,G.Namkoong,E.Trybus,A.Doolittle,S.Kurtz,Design,Growt h,Fabrication and
Characterization of High-BandGap InGaN/GaN Solar Cells, Proc. of the IEEE 4th World Conference on Photovoltaic Energy Conversion, Waikoloa, Hawaii, May 7-12, 2006.
[3] RudigerQuay, GalliumNitrideElectronics, SpringerSeriesInMaterials science 96, 2008, 30.
[4] H. Morkoc, Nitride Semi-conductor and Devices, Springer Series in Materials Science 32, 1999, 73.
[5] O. Ambacher, J. Majewski, C. Miskys, A. Link, M. Hermann, M. Eickhoff, M. Stutzmann, F. Bernerdini, V. Fiorentini, V. Tilak, B.
Schaff, L. F. Eastman, Pyroelectric properties of Al(In)GaN/GaN hetero and quantum well structures, J. Phys.: Condens. Matter,
vol. 14 (2002) 3399-3434,
[6] Omkar Jani, Ian Ferguson, Christiana Honsberg, Sarah Kurtz, Design and characterization of GaN/InGaN solar cells, Applied
Physics Letters 91 (2007) 132117-1-3
[7] E.A.Berkman,N.A.El-Masry,A.Emara,ands.M.Bedair,Nearlylattice-matched n, i, and p layers for InGaN p-i-n photodiodes in the
365–500 nm spectral range, Appl. Phys.Lett. 92 (2008) 101118-1-3
[8] M.J.Bergmann,U.Ozgur,J.Casey,H.O.Everitt and J.F. Muth, Ordinary and extraordinary refractive indices for AlxGa1-xN epitaxial
layers, Appl. Phys. Lett. 75 (1999) 67-69.
[9] Omkar Jani, Christiana Honsberg, Ali Asghar, David Nicol, Ian Ferguson, Alan Dwliffle, Sarah Kurtz Characterization and analysis
of InGaN photovoltaic devices, Photovoltaic 31st IEEE Specialists Conference, Lake Buena, Vista, FL Jan. 3-5 (2005)
[10] Jenny Nelson "The Physics of Solar Cells." Imperial College Press.(2003).ISBN978-1-86094-340-9.
http://www.solarfreaks.com/download/file.php?id=281

Abstract: Over the years, a variety of other linear transforms have been developed which include discrete Fourier transform (DFT), discrete wavelet transform (DWT) and discrete cosine transform (DCT) and many more, each with its own advantages and disadvantages. Among these techniques, DWT has been proven to be very efficient for ECG signal coding. It is proposed to develop, a hybrid two-stage ECG signal compressor based on DCT and DWT. Proposed method is hybrid ECG compression technique based on wavelet transformation of the DCT coefficients of the signal. Interaction of DCT analysis with DWT transformations, signal thresholding and coding are a few of the many outstanding challenges in ECG compression. Proposed method will offer optimized CR and PRD, which would be suitable for most monitoring and diagnostic applications.
Keywords: DCT, DWT, Wavelet, Image Processing, Signal Compression.

[1] http://www.physionet.org/physiobank/database/mitdb
[2] A Comparison of Single Lead ECG Data Compression Techniques.
[3] Al-Shrouf, A., Abo-Zahhad, M. and Ahmed, S.M., 2003, A novel compression algorithm for electrocardiogram signals based on the
linear prediction of the wavelet coefficients. Digital Signal Processing, 13, 604–622.
[4] Sabah, M.A. and Abo-Zahhad, M., 2001, A new hybrid algorithm for ECG signal compression based on the wavelet transformation.
Medical Engineering and Physics, 24, 50–66
[5] Abo-Zahhad, M. and Rajoub, B.A., 2002, an effective coding technique for the compression of one-dimensional signals using
wavelets. Medical Engineering and Physics, 24, 185–199.
[6] Manikandan, M.S. and Dandapat, S., 2007, Wavelet thresholding based ECG compression using USZZQ and Huffman coding of
DSM. Biomedical Signal Processing and Coding, 1, 261–270.
[7] Miaou, S. and Yen, H., 2000, Quality driven gold washing adaptive vector quantization and its application to ECG data
compression. IEEE Transactions on Biomedical discrete cosine transform and discrete wavelet transform for ECG signal
compression has been presented & their combination removes Engineering, 47, 209–218.
[8] Leonardo Vidal Batista a, b, c,*, Elmar Uwe Kurt Melcher a, Luis Carlos Carvalho b, 2001, Compression of ECG signals by
optimized quantization of discrete cosine transform coefficients, Medical Engineering & Physics 23 (2001) 127–134
[9] Zigel, Y., Cohen, A. and Kats, A., 2000, the weighted diagnostic distortion (WDD) measure for ECG signal compression. IEEE
Transactions on Biomedical Engineering, 47, 1422–1430.
[10] Lu, Z., Kim, D. and Pearlman, W., 2000, Wavelet compression of ECG signals by set partitioning in hierarchical trees algorithm.
IEEE Transactions on Biomedical Engineering, 47, 849–856.

Abstract:Various methods have been proposed and developed for video shot boundary detection. Commonly used method for shot detection is Block Matching Algorithm. It is the most commonly used motion estimation technique. Various block matching algorithms have been proposed for shot detection such as Exhaustive Search, Three Step Search, New Three Step Search, Simple and Efficient Search, Four Step Search, Diamond Search, Adaptive Rood Pattern Search. This paper presents the comparative study of various Block Matching Algorithm used for boundary detection in videos.
Keywords: Block Matching, Motion Estimation, Motion Vectors, PSNR.

[1] Video shot boundary detection using motion activity descriptor Abdelati Malek Amel, Ben Abdelali Abdessalem and Mtibaa
Abdellatif, april 2010.
[2] Aroh Barjatya, "Block Matching Algorithms For Motion Estimation, "Student Member, IEEE, DIP 6620 Spring 2004 Final Project
paper.
[3] Jianhua Lu, and Ming L. Liou, "A Simple and Efficent Search Algorithm for Block-Matching Motion Estimation", IEEE Trans.
Circuits And Systems For Video Technology, vol 7, no. 2, pp. 429-433, April 1997
[4] Lai-Man Po, and Wing-Chung Ma, "A Novel Four-Step Search Algorithm for Fast Block Motion Estimation", IEEE Trans. Circuits
And Systems For Video Technology, vol 6, no. 3, pp. 313-317, June 1996.
[5] Shan Zhu, and Kai-Kuang Ma, " A New Diamond Search Algorithm for Fast Block-Matching Motion Estimation", IEEE Trans.
Image Processing, vol 9, no. 2, pp. 287-290, February 2000.
[6] Yao Nie, and Kai-Kuang Ma, "Adaptive Rood Pattern Search for Fast Block-Matching Motion Estimation", IEEE Trans. Image
Processing, vol 11, no. 12, pp. 1442-1448, December 2002.
[7] Renxiang Li, Bing Zeng, and Ming L. Liou, "A New Three-Step Search Algorithm for Block Motion
[8] Estimation", IEEE Transactions on Circuits and Systems for Video Technology, Vol. 4, No. 4, pp. 438-442, August 1994.
[9] Chun-Ho Cheung, and Lai-Man Po, "A Novel Small Cross-Diamond Search Algorithm for Fast Video Coding and Video
Conferencing Applications", Proc. IEEE ICIP, September 2002.
[10] Chun-Ho Cheung, and Lai-Man Po, "A Novel Cross-Diamond Search Algorithm for Fast Block Motion Estimation", IEEE Trans.
CircuitsAnd Systems For Video Technology, vol 12., no. 12, pp. 1168-1177, December 2002.