The Archimedes screw turbine (AST) is the most sustainable mini-hydropower extraction method that offers number of economic, social, and environmental advantages. Nowadays, many researchers are interested in AST development as it is considered a new technology. Currently, a lot of researchers are conducting experimental testing of the screws, comparing their reliability with computational fluid dynamic (CFD) analyses. Almost all of them are lab-scale testing models that claiming an average 80% efficiency for low pitch angles. In the case of a real site with a small inclination angle, the length of the screw is large enough to cause severe problems, specially related to bending of the screw. Therefore, this research was conducted to analyze the CFD flow field in a real site-scale AST with the maximum possible inclination of 45 degrees. In addition, the design was done without the upper and lower reservoir as it was conceived as a run-of-river flow system. The simulated real scale AST result showed a maximum efficiency of around 82% for a 5.2 m hydraulic head and 0.232 m³/s discharge. Many researchers claim above 80% efficiency for low inclination angle ASTs with reservoirs. This CFD study indicates that even higher inclination angle ASTs can achieve 80% efficiency in run-of-river; real-scale applications.

Traffic noise plays a significant role in worldwide urban areas, impacting public health and quality of life.This study has focused on assessing traffic noise levels at selected locations in Kandy, Sri Lanka, using simulation-based modelling techniques. SoundPLAN was used as the modelling software, and the study was carried out using three distinct traffic noise models: ASJ RTN 2013, CNOSSOS-EU 2015 and FHWA TNM 2.5 to map the noise propagation. Real-time sound measurements were also taken to validate a model. According to the results, the ASJ RTN 2013 model illustrated the lowest percentage error for both daytime and nighttime simulations alongside the measured sound data. Thus, it was chosen as the best match of the three models used. Furthermore, the chosen traffic noise model was further used to map the noise propagation around a complex junction within the same city. Then, the simulated results were used to assess noise pollution levels. The main intention of this study is to demonstrate the use of established traffic noise models in predicting traffic noise in Sri Lanka. It can be taken as a sample study for future investigations into traffic noise management and mitigation strategies in Sri Lanka.

Representing the velocity at a tidal energy extraction site in a standardized manner is essential for the development of the tidal energy sector. The International Electrotechnical Commission (IEC) have issued a technical specification to determine the mean representative current velocity (MRV) relative to a tidal energy converter (TEC). This method determines the MRV using an acoustic Doppler profiler (ADP). This is used to evaluate the power performance of a TEC and so can have a significant influence on the power performance uncertainties, due to the cubed relationship of the MRV and power. This paper investigates these uncertainties in the MRV by considering four sources of uncertainty in the ADP. These are turbulence intensity, tilt, Doppler noise and beam misalignment of an ADP. A synthetically generated dataset is used to define current velocity and profile using the characteristics of currents and ADP. The generated synthetic dataset is processed to calculate the MRV based on the standard IEC method. An alternative method to calculate the MRV, called the temporal-spatial method (TSM), is proposed and the two methodologies are used to assess the error of the MRV. A sensitivity analysis shows that the errors of the MRV based on the standard IEC method are always higher than the TSM. The biases in the MRV based on the different combinations of the uncertainty are investigated and it is found that the bias for the MRVs based on the TSM method is generally less than that of the IEC method.