Abstract: This paper presents the design, construction and implementation of auto-intensity control of solar powered LED street light. The system consists of charge controller circuit, load intensity control circuit and DC to AC converter circuit. When a battery voltage reaches the regulation set point, the PWM algorithm slowly reduces the charging current to avoid heating and gassing of the battery, yet the charging continues to return the maximum amount of energy to the battery in the shortest time.The results are used to determine the size of the panel and the number of batteries required to guarantee that the lamp would work a pre-set number of days without failure. DC to AC converter is used to get AC current for using digital watch, cc camera and others. Real-life data was collected by the prototype system and after verifying by computer simulations it was used to evaluate the long-term performance of the system. An economic analysis is performed. The circuit is designed and simulated.

Abstract: As the eutrophication of water bodies is increasing, mass propagation of phytoplankton is a big problem in dams, reservoirs and lakes, with levels of nitrogen and phosphorus increasing in both developed and developing countries. The occurrence of of blue algae, a worldwide problem, is also due to the growth of a kind of phytoplankton. Therefore, in water area monitoring, it is extremely important to quantify the biomass of phytoplankton. Chlorophyll-a has been used in the biomass quantification of phytoplankton, but for this purpose, expensive analytical instruments such as spectrophotometers and fluorescence sensors are required. Therefore, in this research, the authors attempted to develop a method to estimate the chlorophyll-a concentration in water by using RGB values from smartphone cameras currently used all over the world. Finally, we created a new index called the Visible Water Resident Index (VWRI) based on the Visible Atmospheric Resident Index (VARI). The coefficient of determination (R2) has an extremely high numerical value of 0.9634.