Department of Electrical & Electronic Engineering

Bangladesh, a country started with a population of 70 million and a GDP of -14% (1972) (1) currently the 44th largest in the world in nominal terms, and 32nd largest by purchasing power parity (2); it is classified among the next eleven emerging market economies and a Frontier market. The rapid growth of this country didn’t come overnight through any single way rather different driving forces along with the supreme efforts of her citizens living home and abroad contributed to its economic development. Here in this essay attempts have been made for some policy reformation and innovation proposals for a sustainable development in the issue of poverty reduction which will eventually lead us to a good situation in Human Development Index.

A new planar square-shaped metamaterial (MTM) structure with dual-band negative refractive index (NRI) and double-negative (DNG) properties in the terahertz regime is proposed in this paper. The MTM unit cell is constructed using identical L-shaped planar resonators and rectangular planar structure over a lead glass substrate. For normal wave incidence, the proposed structure exhibits broad and dual-band NRI properties at 3.08-3.64 THz and 4.10-4.37 THz. Realized NRI bandwidth at these two frequency bands are 0.56 THz and 0.27 THz, respectively. At two distinct frequency bands, 2.85-3.66 THz and 4-4.46 THz, negative effective permittivity is observed. Negative effective permeability and dual-band DNG properties are obtained in the frequency ranges of 3.44-3.62 THz and 4.16-4.21 THz. Acquired bandwidth of these DNG regions are 0.18 THz and 0.05 THz, respectively. Simulated results are indicative of effective utilization of the unit cell in THz applications. The design is appealing in THz applications because of its unique planar design, broad and dual-band NRI and DNG properties. Single negative (SNG) and near zero refractive index (NZRI) properties are also attained in the same environment by this unit cell. NZRI property is acquired over a 1.4 THz bandwidth ranging from 1.68-3.08 THz. This unit cell has potential application in multiple frequency spectroscopy detection of drugs and explosive materials, along with the design of THz directional antennas, cloaking devices, absorbers, modulators, sensors etc. Index Terms-double negative property, dual-band, metamaterial, near zero refractive index, negative refractive index

This paper considers an array unit of a metamaterial (MTM) structure and examines the performance of various configurations of the array unit. Array units of a square-shaped opposingly facing L-structured MTM with double negative (DNG) and negative refractive index (NRI) features are explored. The top layer of the structure is formed by a copperbased SRR structure with additional splits and rectangular inner strips atop a lead glass substrate. Negative refraction bandwidth as well as DNG bandwidth, where both negative permittivity and permeability are attained, has been discovered in the array unit and different configurations of the array unit. The negative index bandwidth of the array unit, 1 × 2 configuration, and 2 × 2 configuration are at 3.774-3.781, 1.563-1.873, 1.532-1.824 THz, respectively. High Figure of Merit (FOM) is attained in all three configuration examined. Peak FOM attained at the array unit and it's 1 × 2 and 2 × 2 topologies are 63, 172, 77, respectively. Effective medium ratio (EMR) of the array unit and it's 1 × 2 and 2 × 2 topologies at 3.75, 1.65, 1.75 THz are 1.97, 2.26, 2.2, respectively. The proposed MTM can be utilized in THz sensing, detection, communication, and other applications.

Crisis of electric power is a common scenario in a developing country. Day by day it's become serious issue due to various factors, such as increasing demand, lower production capacity and transmission losses, etc. For those reasons Instantaneous Power Supply System (IPS) is able to attract the focus of many consumers, especially for house hold purposes. The authors of this paper have been trying to propose a new method to store waste energy of a running vehicle into a battery and then it will use in IPS. We know when an automobile is running or even in breaking position for entry of passenger or stopping by traffic jam, always fly wheel is rotating up to stopping of engine. We are planning to connect the fly wheel to dynamo by suitable belt or pulley system. When a vehicle is stop in a traffic jam, our proposed system works automatically by help of a sensor. In that case fly wheel and dynamo is engaged and produce electricity, which is store in a battery. If the vehicle is start to running then sensor disconnect the connection between dynamo and fly wheel. That is engine power is fully used for vehicle acceleration. In this way when the automobile is finally stopped after end of journey, we remove the battery and use it in IPS system. Thus we can utilize the waste energy of IC engine and producing electricity reduces the load of national grid.

Electricity is a basic need of our daily life. Our daily life depends on the amount of electricity usage. But in our country only 40 percent people has the access of the electricity. Moreover fossil fuel is non-renewable, so it is diminishing day-by-day. As a result we need different solution of electricity generation. In our country, so renewable energy is becoming more popular day by day along with the world. Solar Energy is one of that kind renewable energy. Its application is increasing day by day. Bangladesh has good availability of solar energy to generate electricity. In this study production of electricity using solar energy in Bangladesh along with the world has been shown in details.

The I-V characteristic curve of solar PV
system shows non-linearity where the desired maximum powe r
point can easily be found. Cuk converter has been used in this
particular system with the purpose of extracting solar power out
of PV arrays with greater stability. For the purpose of assessing
the duty cycles of cuk, MPPT controller is used. This converter is
the most suitable DC chopper for evaluating ripple free current
in PV side. The energy transfer from source to load is continuous
regardless of the state of the MOSFET switch. Voltage can be
stepped up or stepped down and the overall performance will be
smooth. For all kinds of simulation and development, MATLAB
Simulink is used. The overall system efficiency, amount of ripple
current on both PV side and load portion, power on both sides
and investigation on system stability under several conditions
have been considered. The simulation result shows that there
exists only 0.06795 percent of ripple in the PV side current which
is almost ripple free and 0.0026 percent ripple in the output
current with respect to the average value of current. Both the
MPPT and the converter efficiency are significantly improved.
Under different solar irradiances, MPPT has shown good
performance. Cuk converter based solar system has given
satisfactory outcome which reflects its utility compared to other
types of dc-dc choppers.

Keywords— Solar PV System, MPPT, Perturbation &
Observation Algorithm, Percent Ripple, Cuk Converter.