312 research outputs found
Modeling and Performance Analysis of GaSb-Based Mid-infrared Vertical Cavity Surface Emitting Laser
No full textThis thesis is submitted to the Department of Electrical and Electronic Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Electrical and Electronic Engineering, May 2010.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 63-68).Strain-dependent and crystal orientation-dependent optical properties and output optical power-input
current characteristics are numerically studied for GalnSb/GalnAlSb mid-infrared quantum well
vertical cavity surface emitting laser (VCSEL). At first physical model of the VCSEL is proposed
and then mathematical formulations is developed taking into account of strain, change in crystal
orientation and piezoelectric field. The results obtained from the model are confirmed with the
published results. To investigate the performances of the proposed VCSEL. wave functions. energy
dispersion profiles, and momentum matrix elements are determined by Schrodinger equation using
finite dilièrence method. The results are calculated for a compressively strained quantum well in
which strain is varied from 0.6% to 1.52% with the change in crystal orientation (001), (111), (110),
(113) and (131). It is tbund that wave function confnenient. energy separation between different
hands and subhands. and magnitude of momentum matrix elements are strongly dependent on strain.
change in crystal orientation and piezoelectric fieId. The injection carrier density-dependent optical
and differential gains are calculated. Typical optical gains are found to he 3115. 3080. 2790. 341 5.
and 2940 cm in (001 ), (110), (111), (113). and (131) crystal orientations, respectively when the
injection carrier density is 3,5x 1018 cm-3. Further, the maximum differential gain is evaluated
2.78x 1018cm-1 (113) orientation (or the injection carrier density 3.0x I 0IXcm-3. Ihe results obtained
in the present stud• indicate that the peak emission wavelength can he tuned from 2.4 µm to 2.25 µm
by changing crystal orientation from (110)10 (111) in the well and harrier materials. It is also found
that the influence of piezoelectric effect is not so remarkable on the optical gain and shift in peal
emission wavelength for the proposed VCSLL.
To understand the output characteristics, the proposed VCSEL. model is converted into PSPICE
equivalent circuit. The results obtained from PSPICE simulation demonstrate that the maximum
output power and the minimum threshold current are associated with the crystal orientation and the
ii umber of quantum wells. The highest optical power and lower threshold current are obtained hen
the crystal orientation is (113) and number of quantum well is three. Furthermore, design of
distributed Bragg reflector indicates 30 and 38 pairs of alternating layer of AlAs0.09 Sb0.91 and GaSb
are used in top and bottom mirror in order to obtain reflectivity 99. 13% and 99.8% reflectivity.Md. Mahbub HasanMaster of Science in Electrical and Electronic Engineerin
Approach
No full textThis study aims to design epitope-based peptides for the utility of vaccine development by targeting glycoprotein G and envelope protein F of Nipah virus (NiV) that, respectively, facilitate attachment and fusion of NiV with host cells. Using various databases and tools, immune parameters of conserved sequence(s) from G and F proteins of different isolates of NiV were tested to predict probable epitope(s). Binding analyses of the peptides with MHC class-I and class-II molecules, epitope conservancy, population coverage, and linear B cell epitope prediction were analyzed. Predicted peptides interacted with seven or more MHC alleles and illustrated population coverage of more than 99% and 95%, for G and F proteins, respectively. The predicted class-I nonamers, SLIDTSSTI and EWISIVPNF, superimposed on the putative decameric B cell epitopes, were also identified as core sequences of the most probable class-II 15-mer peptides GPKVSLIDTSSTITI and EWISIVPNFILVRNT. These peptides were further validated for their binding to specific HLA alleles using in silico docking technique. Our in silico analysis suggested that the predicted epitopes, either GPKVSLIDTSSTITI or EWISIVPNFILVRNT, could be a better choice as universal vaccine component against NiV irrespective of different isolates which may elicit both humoral and cell-mediated immunity
Growth and Poverty in Pakistan: Implications for Governance
No full textAccording to the Economic Surveys, Pakistan’s real GDP has grown at an average annual rate of 6.8 percent in the 1960s, 4.8 percent in the 1970s, 6.5 percent in the 1980s and 4.7 percent in the 1990s. However, that did not seem to have mitigated poverty as parallel to this growth the number of poor also kept swelling. Although different estimates put number of poor in Pakistan around 50 million, the actual could be more [Ahmad (2001)]. The average growth rates in the first halfcentury of Pakistan have been around 2 percent [Hasan (1997)]. It is pertinent to state that this discussion paper is not an attempt to challenge the figures either of the growth rates or the numbers of the poor in Pakistan. This is rather an attempt to understand the correlation of governance with growth on one hand and poverty on the other. It offers conceptual analysis of the concepts and their respective interpretation, explanation, application and ensuing misunderstandings. This paper has also attempted to challenge certain (usual) assumptions and perceptions regarding the role and relationship of growth and governance in reducing poverty in Pakistan. One has pointed out that most of the studies on the subject focus on symptoms and not the causes of poverty. This leads to on one hand growth of poverty, as poverty does not seem to halt despite certain evidence of relatively high growth particularly in 1960s. On the other hand we witness poverty of growth as whatever growth we have had it has hitherto failed either translating into corresponding mitigation of poverty or equitable collective prosperity. This is because there have not been efforts at governance level to ensure equity of impact of growth through adequate distribution mechanisms, sufficient social and human investments leading to education and skill development of women and men, who in turn could benefit from opportunities arising by way of process of economic growth.
TIME-COURSE MORTALITY AND RADIOSENSITIVITY INDICES IN GAMMA-IRRADIATED TRIBOLIUM SPP. (COLEOPTERA: TENEBRIONIDAE
No full textThe effect of gamma irradiation on the time-course mortality and radiosensitivity indices in 1- and 10-day-old adult Tribolium anaphe, T. brevicornis, T. castaneum, T. destructor and T. freemani, was studied. Longevity was always adversely affected by irradiation, and it was linearly dependent on the dose rate. Except for 10-day-old adults, all the insects died within 12 weeks of γ-irradiation at 4 and 5 krad. In addition, T. destructor was markedly more radioresistant at all dose levels, and lived longer than the other species. The mean survival times of adults were generally shorter in females than in males for all species. The radiosensitivity indices did not vary widely among the species, but decreased as the dose increased in all the species, indicating that the resistance of the species was dose-dependent. RÉSUMÉ On a étudié l'effet des radiations gamma sur l'évolution de la mortalité et les indices de radiosensibilité d'adultes de Tribolium anaphe, T. brevicornis, T. castaneum, T. destructor et T. freemani, âgés de 1 et 10 jours. La longévité est toujours négativement affectée par les radiations et elle est linéairement liée à la dose. A l'exception des adultes âgés de 10 jours, tous les insectes meurent en moins de 12 semaines avec des radiations gamma à 4 et 5 krad. De plus,T. destructor est nettement plus radiorésistant à toutes les doses, et vit plus longtemps que les autres espèces. Les temps moyens de survie des adultes sont généralement plus courts chez les femelles que chez les mâles pour toutes les espèces. Les indices de radiosensibilité ne varient pas beaucoup entre les espèces, mais décroissent avec l'augmentation de la dose chez toutes les espèces, indiquant que la résistance des espèces est dose-dépendante
Analysis of Dynamic Filtering Properties for Vocal-Tract during Bangla Vowel and Vowel-Consonant-Vowel Sequence Production
No full textThis thesis is submitted to the Department of Electrical and Electronic Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Electrical and Electronic Engineering, December, 2016.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 51-53).This thesis deals with the acoustic analysis of dynamic filtering properties for vocal-tract and the
perceptional space of Bangla vowel. Here we capture Bangla vowel, vowel-consonant-vowel
speech signal from native Bangla Speakers. Acoustic study of dynamic-shape of vocal-tract for
Bangla vowels and vowel-consonant-vowel (VCV) sequences are carried out based on dispersion
and cross-correlation of linear predictive coding (LPC) filtering coefficients and short-time
Fourier transform (STFT) of formant trajectory. The standard deviation of LPC filtering
coefficients and transitional energy of formant trajectories indicate the dynamics of vocal-tract.
The consonantal-constriction in VCV sequence accelerates the vocal-tract transitional nature and
the transitional nature yields lower-valued cross-correlation with more stable vowels. Fourier
transform technique is utilized to determine the cross-correlation of two unequal length LPC
trajectories. In the domain of vowel perception, speaker invariant principal components are
determined from the multidimensional perceptual space for comparatively stable Bangla vowels.
Linguistic content base multidimensional vector space can be formed using the formant
frequencies and its dispersion related statistical moments and the well reorganization-able
vowels may maintain a separable distance in the multidimensional space. In this work,
perceptual vectors and their associated energies are evaluated by determining the principal
components of the multidimensional space. Speaker invariance is numerically evaluated using
the correlation with principal components of native Bangla speakers. In this research, an
algorithm is also proposed for the determination of energy based on the redundancies of the
canonical variates for the inter-speaker vowel consistency.Sathi Rani MitraMaster of Science in Electrical and Electronic Engineerin
Community development practice : From Canadian and global perspectives
No full textCommunity Development Practice is a resource book for students, social workers and community leaders. The author and contributors have defined key concepts in this book and discussed theories, models, frameworks, and tools applied in community development practice in Canada and globally. The author used images, videos, and podcasts in each chapter to make this book purely digital, accessible, and interesting for readers. Academics, Community Development practitioners, and community activists from Canada and worldwide have contributed to this book
Two decades of endemic dengue in Bangladesh (2000–2022): trends, seasonality, and impact of temperature and rainfall patterns on transmission dynamics
No full textThe objectives of this study were to compare dengue virus (DENV) cases, deaths, case-fatality ratio [CFR], and meteorological parameters between the first and the recent decades of this century (2000-2010 vs. 2011-2022) and to describe the trends, seasonality, and impact of change of temperature and rainfall patterns on transmission dynamics of dengue in Bangladesh. For the period 2000-2022, dengue cases and death data from Bangladesh's Ministry of Health and Family Welfare's website, and meteorological data from the Bangladesh Meteorological Department were analyzed. A Poisson regression model was performed to identify the impact of meteorological parameters on the monthly dengue cases. A forecast of dengue cases was performed using an autoregressive integrated moving average model. Over the past 23 yr, a total of 244,246 dengue cases were reported including 849 deaths (CFR = 0.35%). The mean annual number of dengue cases increased 8 times during the second decade, with 2,216 cases during 2000-2010 vs. 18,321 cases during 2011-2022. The mean annual number of deaths doubled (21 vs. 46), but the overall CFR has decreased by one-third (0.69% vs. 0.23%). Concurrently, the annual mean temperature increased by 0.49 °C, and rainfall decreased by 314 mm with altered precipitation seasonality. Monthly mean temperature (Incidence risk ratio [IRR]: 1.26), first-lagged rainfall (IRR: 1.08), and second-lagged rainfall (IRR: 1.17) were significantly associated with monthly dengue cases. The increased local temperature and changes in rainfall seasonality might have contributed to the increased dengue cases in Bangladesh
Two decades of endemic dengue in Bangladesh (2000–2022): trends, seasonality, and impact of temperature and rainfall patterns on transmission dynamics
No full textThe objectives of this study were to compare dengue virus (DENV) cases, deaths, case-fatality ratio [CFR], and meteorological parameters between the first and the recent decades of this century (2000-2010 vs. 2011-2022) and to describe the trends, seasonality, and impact of change of temperature and rainfall patterns on transmission dynamics of dengue in Bangladesh. For the period 2000-2022, dengue cases and death data from Bangladesh's Ministry of Health and Family Welfare's website, and meteorological data from the Bangladesh Meteorological Department were analyzed. A Poisson regression model was performed to identify the impact of meteorological parameters on the monthly dengue cases. A forecast of dengue cases was performed using an autoregressive integrated moving average model. Over the past 23 yr, a total of 244,246 dengue cases were reported including 849 deaths (CFR = 0.35%). The mean annual number of dengue cases increased 8 times during the second decade, with 2,216 cases during 2000-2010 vs. 18,321 cases during 2011-2022. The mean annual number of deaths doubled (21 vs. 46), but the overall CFR has decreased by one-third (0.69% vs. 0.23%). Concurrently, the annual mean temperature increased by 0.49 °C, and rainfall decreased by 314 mm with altered precipitation seasonality. Monthly mean temperature (Incidence risk ratio [IRR]: 1.26), first-lagged rainfall (IRR: 1.08), and second-lagged rainfall (IRR: 1.17) were significantly associated with monthly dengue cases. The increased local temperature and changes in rainfall seasonality might have contributed to the increased dengue cases in Bangladesh
Mating competitiveness of adult males of Tribolium spp (Coleoptera: Tenebrionidae) developing from irradiated pupae
No full textInvestigation of the Effect of MFCC Variation on the Convolutional Neural Network-based Speech Classification
No full text- …
