Robust Diversity-based Sine-Cosine Algorithm for Optimizing Hydropower Multi-reservoir Systems

Hydropower energy generation depends on the available water resources. Therefore, planning and operation of the water resource systems are paramount tasks for energy management. Since reservoirs are one of the important components of water resources systems, extracting optimal operating policies for proper management of energy generated from these systems is an imperative step. Optimizing reservoir system operation (ORSO) is a non-linear, large-scale, and non-convex problem with a large number of constraints and decision variables. To solve ORSO problem effectively, a robust diversity-based, sine-cosine algorithm (RDB-SCA) is developed in the present study by introducing several strategies to balance the global exploration and local exploitation ability and to achieve accurate and reliable solutions. An efficient linear operation rule is coupled with the RDB-SCA to maximize the energy generation. The proposed method is then applied to a real-world, multi-reservoir system to extract optimal operational policies and, consequently, maximize the energy production. It is shown that the RDB-SCA is able to generate 24, 14, and 6% more energy than the original SCA, respectively for 2-, 3-, and 4-reservoir systems. The present findings are useful to suggest guidelines for efficient operation of hydropower multi-reservoir systems. This paper is supported by https://imanahmadianfar.com/codes.

     

Correlationships between clearness index and relative sunshine duration for Sudan

The clearness index for 16 meteorological stations in Sudan has been expressed in terms of the fraction of bright sunshine duration, applying a variety of regression forms, namely linear, exponential, power and second-order polynomial. The significance and performance characteristics of the relations have been viewed using several statistical procedures. Although all of the four relationships are empirical and exhibit relative discrepancies, it has been found that they can reasonably be used to represent the underlying effect of relative duration of sunshine on clearness index for mean values. The estimates of the relationships are statistically significant at the 99.9% confidence level. For around 85% of the cases, the absolute error is fairly less than 4%. No estimate is found to fall beyond about ±10% accuracy level. Unless otherwise investigated under extreme conditions, especially S/S_o = 0 and 1, the predictive value of the relations remains questionable for values of S/S_o outside the ranges covered herein. From the bulk of the data available, the important finding is that solar radiation is plentiful in this vast country and could be regarded as an essential, renewable source of energy for various applications.     

Study of Hydrology and Drought in the Flood Region of Sudan

ABSTRACT

An attempt is made to thoroughly investigate the important hydrological features ofhe flood region that is located in the southern part of Sudan. The hydrologic data that were used in the study include temperature, precipitation, sunshine duration. radiation, humidity, wind speed, and evaporation. The investigation also includes the stream flow records of the Nile River in the region. In this region, a huge amount of the Nile water is lost by evaporation and overspilling. The hydrological data of Malakal meteorological station, taken as the index station, and the long-term flow data of the White Nile and its principal tributary, the Sobat, have been analyzed. The effect of changes in the behavior of the hydrological factors on the degree of aridity is also assessed. The study clearly indicates significant changes in the hydrological behavior of the region characterized by an increase in temperature levels and a substantial reduction in rainfall and river flows.     

Estimation of solar radiation for the Republic of Sudan

Measurements of global solar radiation and duration of bright sunshine for the Republic of Sudan have been presented. For this purpose, nine index stations spread all over Sudan are chosen. The brightness ratio n/N, to be defined later, ranges between 0.373 and 0.923. The results show huge resources of solar energy available in Sudan. The correlationships between the global solar radiation and bright sunshine duration for this vast country have been developed by performing regression analysis using three models, namely linear, exponential and power. Excellent correlations were obtained for all three models, but the power one was found very marginally superior over the others. This suggests that the linear relationship can still be used with a great degree of accuracy. The correlationships have also been used to estimate evaporation rates. Further, the Piche coefficients (C_p), defined as the ratios of estimated evaporation rates to Piche measurements, have been obtained and compared with those suggested by other investigators. A reasonably good agreement has been found.     

Microwave pre‐oxidation for polyacrylonitrile precursor coated with nano‐carbon black

A surface coating was successfully applied through dipping the polyacrylonitrile (PAN) precursor fibers in a carbon black (CB) bath containing a hydrolyzed binder. The coated fibers were pre‐oxidized over the microwave furnace at temperatures ranging from 100°C to 170°C for different heating times. The changes in chemical structure were studied by Fourier transfer infrared spectroscopy combined with elemental analyzer. X‐ray diffraction was employed to study the crystalline structure and its related parameters. Differential scanning calorimeter and thermogravimetry were used for thermal analysis. In addition, the fiber morphology and the mechanical properties were also evaluated. Scanning electron microscopy results confirmed the presence of CB on the surface of PAN precursor. The analysis in the chemical structure showed an apparent response of coated PAN fibers to the microwave heating, since the microwave field induced the cyclization and crosslinking reactions. The crystallinity and the crystallite height decreased. Furthermore, the tensile strength and elongation of pre‐oxidized fibers decreased with the increase of heating time. The measured oxygen content revealed that the pre‐oxidized fibers can withstand the high temperatures on the following stage (carbonization). POLYM. ENG. SCI., 59:457–464, 2019. © 2018 Society of Plastics Engineers