A numerical simulation and analysis was performed to investigate the effect of absorber and buffer layer band gap grading and on a Copper-Indium-Gallium-Diselenide (CIGS) solar cell. The software used is the Solar Cell Capacitance Simulator (SCAPS). The absorber and buffer layer energy band structures’ effect on the cell’s output parameters such as open circuit voltage, short circuit current density, fill factor and efficiency were extensively simulated. Two structures of the energy band gap were simulated and studied for each of the absorber and buffer layer. The simulation was done on the uniform structure in which the energy band gap is constant throughout the layer. It was then continued on the cell with graded band structure, where the energy band gap of the material is varied throughout the layer. It was found that the cell with graded band structure in absorber and buffer layer had demonstrated higher efficiency and better performance in comparison with the cell with uniform band gap structure.
Controlled humidity environment is of significance in many scientific researches and experiments. In most laboratory-scale atmospheric chambers, an electrical temperature-based control system is used to adjust humidity. Since these chambers are not affordable in every laboratory, other low cost chambers using nitrogen gas or silica gel are used to adjust humidity. In this paper, a mechanism was developed to control the relative humidity in closed lab-scale chambers. Humidification is done by spraying water through a blower fan while de-humidification is by pumping air through silica gel as well as nitrogen gas injection. A Mamdani type fuzzy controller was designed to control the components and relative humidity. The results show the proposed system and controller can adjust and maintain relative humidity from 41% to 100% with maximum overshoot of 1% and the maximum range of error of steady state of 1.2 %.
A programmable CMOS delay line circuit with microsecond delay range and adjustable duty cycle is proposed. Through circuit simulation, approximately 2μs delay range can be achieved using 10-bit counter operating at a clock frequency of 500MHz. Utilising synchronous counters instead of synchronous latches has significantly reduced the large occupied active silicon area as well as the huge power consumption. The generated coarse time delay has shown excellent linearity and immunity to PVT variations. The proposed CMOS delay line is designed using a standard 0.13μm Silterra CMOS technology. The active layout area is (101 x 142) μm2, and the total power consumption is only 0.1 μW.
The use of electroosmotic is fast becoming a proven technique for manipulating particles in microfluidic
systems. Several approaches were experimented to improve the force and thus the moving particles in
the fluid. This paper will study the effect of microelectrode on the moving particles in latex using a
particle image velocimetry and to test the velocity of particles movement at various frequencies from
10kHz to 500kHz. The result shows the behaviour of latex particles at different frequencies varying
from low frequencies up to high frequencies under AC electrokinetic forces such as dielectrophoresis
(DEP) and AC electroosmosis (ACEO).