1,721,071 research outputs found
Hydrostatic Pressure,electric And Magnetic Field Effects On Shallow Donor Impurity States And Photoionization Cross Section In Cylindrical Gaas-ga1-xalxas Quantum Dots
No full textUsing the variational method and the effective mass approximation, we have calculated the influence of applied electric and magnetic fields, both in the axial direction, and hydrostatic pressure on the binding energy and photoionization cross section for on center shallow-donor impurities in cylindrical shaped GaAs-Ga1-x Alx As quantum dots. For the hydrostatic pressure effects the Γ-X crossover has been taken into account. Different values for the structure dimensions, applied electric and magnetic fields, hydrostatic pressure, and energy of the incident photon have been considered. Because the parallel polarization of the incident radiation has been considered, the main effects on the photoionization cross section are associated with the applied electric field. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.2463626629Wolford, D.J., Bradley, J.A., (1985) Solid State Commun., 53, p. 1069Burnett, J.H., Cheong, H.M., Paul, W., Koteles, E.S., Elman, B., (1993) Phys. Rev. B, 47, p. 1991Elabsy, A.M., (1993) Superlattices Microstruct, 14, p. 65Elabsy, A.M., (1994) J. Phys. Condens. Matter, 6, p. 10025Adachi, S., (1992) Physical Properties of III - V Semiconductor, p. 106. , Compounds (John Wiley & Sons)Yu, P.Y., Cardona, M., (1995) Fundamentals of Semiconductors, p. 130. , (Springer, Berlin)Duque, C.A., Montes, A., Morales, A.L., Porras-Montenegro, N., (1997) J. Phys. Condens. Matter, 9, p. 5977Morales, A.L., Montes, A., López, S.Y., Duque, C.A., (2002) J. Phys. Condens. Matter, 14, p. 987Raigoza, N., Duque, C.A., Porras-Montenegro, N., Oliveira, L.E., (2006) Physica B, 371, p. 153Pérez-Merchancano, S.T., Parédes-Gutierrez, H., Silva-Valencia, J., (2007) J. Phys. Condens. Matter, 19, p. 026225Kasapoglu, E., Sari, H., Sökmen, I., (2004) Physica B, 353, p. 345Correa, J.D., Porras-Montenegro, N., Duque, C.A., (2004) Phys. Status Solidi B, 241, p. 2440Zhao, Z., Zeng, J., Ding, Z., Wang, X., Hou, J., Zhang, Z., (2007) J. Appl. Phys., 102, p. 053509Peter, A.J., Navaneethakrishnan, K., (2008) Superlattices Microstruct, 43, p. 63Xia, C., Liu, Y., Wei, S., (2008) Appl. Surf. Sci., 254, p. 3479Mughnetsyan, V.N., Barseghyan, M.G., Kirakosyan, A.A., (2008) Physica E, 40, p. 654Sahin, M., (2008) Phys. Rev. B, 77, p. 045317Zrenner, A., Butov, L.V., Hagn, M., Abstreiter, G., Böhm, G., Weimann, G., (1994) Phys. Rev. Lett., 72, p. 3382Itskevich, I.E., Lyapin, S.G., Troyan, I.A., Klipstein, P.C., Eaves, L., Main, P.C., Henini, M., (1998) Phys. Rev. BButov, L.V., Shashkin, A.A., Dolgopolov, V.T., Campman, K.L., Gossard, A.C., (1999) Phys. Rev. B, 60, p. 8753Ma, B.S., Wang, X.D., Su, F.H., Fang, Z.L., Ding, K., Niu, Z.C., Li, G.H., (2004) J. Appl. Phys., 95, p. 933Schildermans, N., Hayne, M., Moshchalkov, V.V., Rastelli, A., Schmidt, O.G., (2005) Phys. Rev. B, 72, p. 115312Sidor, Y., Partoens, B., Peeters, F.M., Schildermans, N., Hayne, M., Moshchalkov, V.V., Rastelli, A., Schmidt, O.G., (2006) Phys. Rev. B, 73, p. 15533
Effects Of Hydrostatic Pressure And Applied Electric Fields On The Exciton States In Gaas - (ga,al)as Quantum Wells
No full textThe effects of both hydrostatic pressure and electric fields applied perpendicular to the layers on the direct-exciton states in single GaAs-(Ga,Al)As quantum wells are studied. Theoretical calculations are performed within the variational procedure, in the framework of the effective-mass and non-degenerate parabolic-band approximations. Both heavy- and light-hole exciton energies and corresponding quantum-confined Bohr radii are obtained. The pressure coefficient is also theoretically evaluated and found in good agreement with available experimental measurements. © 2005 Elsevier B.V. All rights reserved.3671-4267274Aspnes, D.E., (1976) Phys. Rev. B, 14, p. 5331Samara, G.A., (1983) Phys. Rev. B, 27, p. 3494Adachi, S., (1985) J. Appl. Phys., 58, pp. R1Venkateswaran, U., Chandrasekhar, M., Chandrasekhar, H.R., Wolfram, T., Ficher, R., Masselink, W.T., Morkoç, H., (1985) Phys. Rev. B, 31, p. 4106Venkateswaran, U., Chandrasekhar, M., Chandrasekhar, H.R., Bojak, B.A., Chambers, F.A., Meese, J.M., (1986) Phys. Rev. B, 33, p. 8416Elabsy, A.M., (1994) J. Phys.: Condens. Matter, 6, p. 10025Burnett, J.H., Cheong, H.M., Paul, W., Koteles, E.S., Elman, B., (1993) Phys. Rev. B, 47, p. 1991Guha, S., Cai, Q., Chandrasekhar, M., Chandrasekhar, H.R., Kim, H., Alvarenga, A.D., Vogelgesang, R., Melloch, M.R., (1998) Phys. Rev. B, 58, p. 7222Zhang, Y., Mascarenhas, A., (1999) Phys. Rev. B, 59, p. 2040Morales, A.L., Montes, A., López, S.Y., Duque, C.A., (2002) J. Phys. Condens. Matter, 14, p. 987Niculescu, E., (2003) Superlatt. Microstruct., 33, p. 103Szymanska, M.H., Littlewood, P.B., (2003) Phys. Rev. B, 67, p. 193305Raigoza, N., Morales, A.L., Montes, A., Porras-Montenegro, N., Duque, C.A., (2004) Phys. Rev. B, 69, p. 045323Morales, A.L., Raigoza, N., Montes, A., Porras-Montenegro, N., Duque, C.A., (2004) Phys. Stat. Sol. (B), 241, p. 3224Kasapoglu, E., Sari, H., Sökmen, I., (2004) Physica B, 353, p. 345Reyes-Gómez, E., Villalba-Chávez, S., Oliveira, L.E., De Dios-Leyva, M., (2004) J. Phys. D Appl. Phys., 37, p. 660López-Gondar, J., D'Albuquerque Castro, E.J., Oliveira, L.E., (1990) Phys. Rev. B, 42, p. 7069Yu, P.Y., Cardona, M., (1998) Fundamentals of Semiconductors, , Springer Berli
Effects Of Hydrostatic Pressure And Crossed Electric And Magnetic Fields On Shallow-donor States In Gaas / Ga1 - X Alx As Quantum Wells
No full textWe have used a variational procedure within the envelope-function and parabolic-band approximations to investigate the effects of hydrostatic pressure and crossed electric and magnetic fields on shallow-donor states in GaAs / Ga1 - x Alx As quantum wells. The donor variational envelope wave function is obtained through a hydrogenic 1s-like wave function and an expansion in a complete set of trigonometrical functions, and a detailed study is performed of the dependence of the donor binding energies on the applied hydrostatic pressure and applied in-growth direction electric and in-plane magnetic fields. © 2007 Elsevier Ltd. All rights reserved.393-4431434Venkateswaran, U., Chandrasekhar, M., Chandrasekhar, H.R., Wolfram, T., Fischer, R., Masselink, W.T., Morkoç, H., (1985) Phys. Rev. B, 31, p. 4106Santiago, R.B., Oliveira, L.E., d'Albuquerque e Castro, J., (1992) Phys. Rev. B, 46, p. 4041Cen, J., Bajaj, K.K., (1993) Phys. Rev. B, 48, p. 8061Neethiulagarajan, A., Balasubramanian, S., (1993) Phys. Rev. B, 48, p. 9114Latgé, A., Porras-Montenegro, N., Oliveira, L.E., (1995) Phys. Rev. B, 51, p. 2259Monozon, B.S., Dunn, J.L., Bates, C.A., (1998) Phys. Stat. Sol. (B), 210, p. 661López, S.Y., Porras-Montenegro, N., Duque, C.A., (2003) Semicond. Sci. Technol., 18, p. 718Brzostowski, B., Kucharczyk, R., (2003) Phys. Rev. B, 67, p. 125305Zhanga, L., Xieb, H.J., (2004) Physica E, 22, p. 791Kasapoglu, E., Sökmen, I., (2005) Physica E, 27, p. 198Peter, A.J., Navaneethakrishnan, K., (2005) Physica B, 366, p. 146Raigoza, N., Morales, A.L., Montes, A., Porras-Montenegro, N., Duque, C.A., (2004) Phys. Rev. B, 69, p. 045323López, S.Y., Porras-Montenegro, N., Duque, C.A., (2005) Physica B, 362, p. 41Xia, J.-B., Fan, W.-J., (1989) Phys. Rev. B, 40, p. 8508. , we refer the reader to this work for details of the calculation of f (z)Raigoza, N., Duque, C.A., Reyes-Gómez, E., Oliveira, L.E., (2006) Phys. Stat. Sol. (B), 243, p. 635Li, E.H., (2000) Physica E, 5, p. 21
Hydrostatic Pressure And Growth-direction Magnetic Field Effects On The Exciton States In Coupled Gaas-(ga, Al)as Quantum Wells
No full textThe effects of hydrostatic pressure and growth-direction applied magnetic fields on the exciton dispersion and in-plane effective mass in coupled GaAs-(Ga, Al)As quantum wells are investigated. Calculations for spatially direct and indirect excitons were performed within the variational procedure in the effective-mass and nondegenerate parabolic band approximations and by taking into account the coupling between the exciton centre-of-mass momentum and its internal structure. The pressure coefficient is also obtained as a function of both the hydrostatic pressure and growth-direction applied magnetic field. © IOP Publishing Ltd.1925Lozovik Yu, E., Berman, O.L., Willander, M., (2002) J. Phys.: Condens. Matter, 14 (47), p. 12457Butov, L.V., Lai, C.W., Ivanov, A.L., Gossard, A.C., Chemla, D.S., (2002) Nature, 417 (6884), p. 47Gor'Kov, L.P., Dzyaloshinskii, I.E., (1968) Sov. Phys.-JETP, 26, p. 449Paquet, D., Rice, T.M., Ueda, K., (1985) Phys. Rev., 32 (8), p. 5208Fritze, M., Perakis, I.E., Getter, A., Knox, W., Goosen, K.W., Cunningham, J.E., Jackson, S.A., (1996) Phys. Rev. Lett., 76 (1), p. 106Butov, L.V., Lai, C.W., Chemla, D.S., Lozovik Yu, E., Campman, K.L., Gossard, A.C., (2001) Phys. Rev. Lett., 87 (21), p. 216804Lozovik Yu, E., Ovchinnikov, I.V., Yu, V.S., Butov, L.V., Chemla, D.S., (2002) Phys. Rev., 65 (23), p. 235304Reyes-Gómez, E., Oliveira, L.E., De Dios-Leyva, M., (2005) Phys. Rev., 71, p. 045316Reyes-Gómez, E., Oliveira, L.E., De Dios-Leyva, M., (2005) Phys. Status Solidi, 242 (9), p. 1829Samara, G.A., (1983) Phys. Rev., 27 (6), p. 3494Venkateswaran, U., Chandrasekhar, M., Chandrasekhar, H.R., Wolfram, T., Ficher, R., Masselink, W.T., Morkoç, H., (1985) Phys. Rev., 31 (6), p. 4106Venkateswaran, U., Chandrasekhar, M., Chandrasekhar, H.R., Bojak, B.A., Chambers, F.A., Meese, J.M., (1986) Phys. Rev., 33 (12), p. 8416Elabsy, A.M., (1994) J. Phys.: Condens. Matter, 6 (46), p. 10025Guha, S., Cai, Q., Chandrasekas, M., Chandrasekar, H.R., Kim, H., Alvarenga, A.D., Vogelgesang, R., Melloch, M.R., (1998) Phys. Rev., 58 (11), p. 7222Morales, A.L., Montes, A., López, S.Y., Duque, C.A., (2002) J. Phys.: Condens. Matter, 14 (5), p. 987Raigoza, N., Duque, C.A., Reyes-Gómez, E., Oliveira, L.E., (2005) Physica, 367 (1-4), p. 267Raigoza, N., Duque, C.A., Reyes-Gómez, E., Oliveira, L.E., (2006) Phys. Status Solidi, 243 (3), p. 635Herbert Li, E., (2000) Physica, 5 (4), p. 215Kopf, R.F., Herman, M.H., Lamont Schones, M., Perley, A.P., Livescu, G., Ohring, M., (1992) J. Appl. Phys., 71 (10), p. 5004Aspnes, D.E., (1976) Phys. Rev., 14 (12), p. 5331Yu, P.Y., Cardona, M., (1998) Fundamentals of Semiconductor
Electron-hole Transitions In Self-assembled Inas/gaas Quantum Dots: Effects Of Applied Magnetic Fields And Hydrostatic Pressure
No full textA theoretical study of the effects of applied magnetic fields and hydrostatic pressure on the electron-hole transition energies in self-assembled InAs/GaAs quantum dots is presented. The effective-mass approximation and a model of a cylindrical-shaped quantum dot with in-plane parabolic potential have been used to describe the InAs/GaAs quantum dots. Present theoretical results are in quite good agreement with experimental measurements of the magnetic field and pressure dependence of the exciton transition energies in InAs/GaAs self-assembled quantum dots. © 2005 Elsevier Ltd. All rights reserved.363-6231233Itskevich, I.E., Henini, M., Carmona, H.A., Eaves, L., Main, P.C., Maude, D.K., Portal, J.C., (1997) Appl. Phys. Lett., 70, p. 505Itskevich, I.E., Lyapin, S.G., Troyan, I.A., Klipstein, P.C., Eaves, L., Main, P.C., Henini, M., (1998) Phys. Rev. B, 58, pp. R4250Barticevic, Z., Pacheco, M., Claro, F., (1995) Phys. Rev. B, 51, p. 14414Pacheco, M., Barticevic, Z., (1999) J. Phys.: Condens. Matter, 11, p. 1079Barticevic, Z., Pacheco, M., Duque, C.A., Oliveira, L.E., (2002) J. Phys.: Condens. Matter, 14, p. 1021Barticevic, Z., Pacheco, M., Duque, C.A., Oliveira, L.E., (2002) J. Appl. Phys., 92, p. 1227Yu, P.Y., Cardona, M., (1998) Fundamentals of Semiconductors, , second ed. Springer BerlinCusack, M.A., Briddon, P.R., Jaros, M., (1996) Phys. Rev. B, 54, pp. R2300Cusack, M.A., Briddon, P.R., Jaros, M., (1997) Phys. Rev. B, 56, p. 4047Adler, F., Geiger, M., Bauknecht, A., Scholz, F., Schweizer, H., Pilkuhn, M.H., Ohnesorge, B., Forchel, A., (1996) J. Appl. Phys., 80, p. 4019Elabsy, A.M., (1993) Physica Scripta, 48, p. 376Stier, O., Grundmann, M., Bimberg, D., (1999) Phys. Rev. B, 59, p. 5688Su-Huai, W., Zunger, A., (1999) Phys. Rev. B, 60, p. 5404Ma, B.S., Wang, X.D., Su, F.H., Fang, Z.L., Ding, K., Niu, Z.C., Li, G.H., (2004) J. Appl. Phys., 95, p. 933Pacheco, M., Barticevic, Z., (2001) Phys. Rev. B, 64, p. 033406Barticevic, Z., Pacheco, M., Duque, C.A., Oliveira, L.E., (2003) Phys. Rev. B, 68, p. 07331
Digital System For Detection And Classification Of Electrical Events
No full textThis paper describes an algorithm to detect and classify electrical events related to power quality. The events detection is based on monitoring the statistical characteristics of the energy of the error signal, which is defined as the difference between the monitored waveform and a sinusoidal wave generated with the same magnitude, frequency, and phase as the fundamental sinusoidal component. The system novel feature is the event recognition based on a neural network that uses the error signal as input. Multi-rate techniques are also employed to improve the system operation for on-line applications. Software tests were performed showing the good performance of the sytem. © 2005 IEEE.54175420Arrillaga, J., Watson, N.R., Bollen, M.H.J., Power quality following deregulation (2000) Proc. of the IEEE, 88 (2), pp. 246-261. , FebDugan, R.C., McGranaghan, M.F., Beaty, H.W., (1996) Electrical Power Systems Quality, , McGraw-HillPoisson, O., Rioual, P., Meunier, M., Detection and measurement of power quality disturbances using wavelet transform (2000) IEEE Trans. on Power Delivery, 15 (3), pp. 1039-1044Ibrahim, W.R.A., Morcos, M.M., Artificial intelligence and advanced mathematical tools for power quality applications: A survey (2002) IEEE Trans. on Power Delivery, 17 (2), pp. 668-673Santoso, S., Grady, W.M., Powers, E.J., Lamoore, J., Bhatt, S.C., Characterization of distribution power quality events with fourier and wavelet transforms (2000) IEEE Trans. on Power Delivery, 15 (1), pp. 247-254Ribeiro, M.V., Duque, C.A., Romano, J.M.T., An improved method for signal processing and compression in power quality evaluation (2004) IEEE Trans. on Power Delivery, 19 (2), pp. 464-471Ramos, F.R., Ribeiro, M.V., Romano, J.M.T., Duque, C.A., On signal processing approach for event detection and compression applied to power quality evaluation (2002) Proc. of the IEEE 10th International Conference on Harmonic and Quality of Power, pp. 133-138Lippmann, R.P., A critical overview of neural network pattern classifiers (1991) IEEE workshop on Neural Network for Signal Processing, pp. 266-275Santoso, S., Powers, E., Grady, W.M., Parsons, A.C., Power quality disturbance waveform recognition using wavelet-based neural classifier-part 1: Theoretical foundation (2000) IEEE Trans. on Power Delivery, 15 (1), pp. 222-228Santoso, S., Powers, E., Grady, W.M., Parsons, A.C., Power quality disturbance waveform recognition using waveletbased neural classifier-part 2: Application (2000) IEEE Trans. on Power Delivery, 15 (1), pp. 229-23
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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