Three essays on Flood Hazard Mitigation : the case of Bangladesh

Thesis (Ph. D. in Urban and Regional Planning)--University of Tsukuba, (A), no. 1789, 1998.3.2

Interference Management Based on RT/nRT Traffic Classification for FFR-Aided Small Cell/Macrocell Heterogeneous Networks

Cellular networks are constantly lagging in terms of the bandwidth needed to support the growing high data rate demands. The system needs to efficiently allocate its frequency spectrum such that the spectrum utilization can be maximized while ensuring the quality of service (QoS) level. Owing to the coexistence of different types of traffic (e.g., real-time (RT) and non-real-time (nRT)) and different types of networks (e.g., small cell and macrocell), ensuring the QoS level for different types of users becomes a challenging issue in wireless networks. Fractional frequency reuse (FFR) is an effective approach for increasing spectrum utilization and reducing interference effects in orthogonal frequency division multiple access networks. In this paper, we propose a new FFR scheme in which bandwidth allocation is based on RT/nRT traffic classification. We consider the coexistence of small cells and macrocells. After applying FFR technique in macrocells, the remaining frequency bands are efficiently allocated among the small cells overlaid by a macrocell. In our proposed scheme, total frequency-band allocations for different macrocells are decided on the basis of the traffic intensity. The transmitted power levels for different frequency bands are controlled based on the level of interference from a nearby frequency band. Frequency bands with a lower level of interference are assigned to the RT traffic to ensure a higher QoS level for the RT traffic. RT traffic calls in macrocell networks are also given a higher priority compared with nRT traffic calls to ensure the low call-blocking rate. Performance analyses show significant improvement under the proposed scheme compared with conventional FFR schemes

Factors Affecting Childhood Immunisation in Bangladesh

This study has examined the coverage of childhood immunisation and tried to identify the factors affecting the acceptance of immunisation practice among children in Bangladesh using the data from Bangladesh Demographic and Health Survey (BDHS) 93-94. Results from multinomial logistic regression analysis indicate that education, occupation, household economic condition, mother’s age at birth, sex of child, mother’s TT immunisation acceptance, mother’s health facility visit, health worker’s visit to mothers, and contraceptive use are the independent variables that have statistically significant association with immunisation acceptance. The most important variable identified is the health worker’s visit to mothers.

Highly Nonlinear and Low Confinement Loss Photonic Crystal Fiber Using GaP Slot Core

This paper presents a triangular lattice photonic crystal fiber with very high nonlinear coefficient. Finite element method (FEM) is used to scrutinize different optical properties of proposed highly nonlinear photonic crystal fiber (HNL-PCF). The HNL-PCF exhibits a high nonlinearity up to $10\times10^{4} W^{-1}km^{-1}$ over the wavelength of 1500 nm to 1700 nm. Moreover, proposed HNL-PCF shows a very low confinement loss of $10^{-3} dB/km$ at 1550 nm wavelength. Furthermore, chromatic dispersion, dispersion slope, effective area etc. are also analyzed thoroughly. The proposed fiber will be a suitable candidate for broadband dispersion compensation, sensor devices and supercontinuum generation.Comment: 4 pages, 6 figures, ICTP conferenc