Wasit Journal of Engineering Sciences

Water covers more than 75% of the earth's surface in the form of the ocean. The ocean investigation is far-fetched because the underwater environment has distinct phenomenal activities. The expansion of human activities inside underwater environments includes environmental monitoring, offshore field exploration, tactical surveillance, scientific data collection, and port security. This led to increased demand for underwater application communication systems. Therefore, the researcher develops many methods for underwater VLC Visible Light Communications. The new technology of blue laser is a type of VLC that has benefits in the application of underwater communications. This research article investigated the benefits of underwater blue laser communication with recursive OFDM for different water types and discovered the effects of baud rate, bit error rate, and latency which affected several subcarriers of the recursive OFDM that have same characteristics but different environments. The design uses a Xilinx Kintex-7 FPGA evaluation board with high-speed analog daughter card ADC/DAC. It is connected to the terminal blue laser diode as a source of transmitting and receiving signals. There are different experiments doing to find the result and discuss the characteristics of blue lasers in underwater communication for different environments.

In recent years, arrays have been widely used in many applications, especially those applications that need high guidance, whether in military, medical, or other applications. Arrays are highly oriental, unlike single antennas. In this work, we analyze the effect of the insulating substrate insulation constant on the 2X2 microstrip patch antenna array at a frequency of 2.4 GHz, which is suitable for WLAN applications. CST Microwave Studio Version 2019 was used to design, simulate, and analyze the proposed model. The bar line feeding technique was used to feed the array. A set of mathematical relationships was used to calculate the dimensions of the array. We simulated and analyzed the array on three dielectric pillars: (FR-4) with a dielectric constant of 4.3, (Polycarbonate) with an isolation constant of 2.9, and (Porcelain) with an isolation constant of 6. The 2X2 array was manufactured and printed on the insulating substrate (FR-4) and the practical results were compared with the simulation results. There was a good agreement between the practical and theoretical results.

Forecasting synthetic hydrologic data is the primary goal of the Stochastic Analysis, Modeling, and Simulation (SAMS) program. This research examined yearly data on the streamflow of the Kut Barrage on the Tigris River spanning 21 years, from 2003 to 2023. The data were converted using the logarithm transformation method, and the skewness and Filliben tests were run to assess the data's normality. To calculate the parameters of the univariate autoregressive moving average (ARMA) model, historical data were examined and ACF and PACF were shown. From these two graphs, it was concluded that the values ​​of the ARMA model orders must be greater than one, and therefore four types of ARMA models were chosen: ARMA (1,1), ARMA (1,2), ARMA (2,1), and ARMA (2,2). The four ARMA models were compared with two criteria corrected Aikaike information criterion (AICC) and the Schwarz information criterion (SIC), which had the lowest values ​​for the ARMA (1,1) forecasting model, which were 15.753 and 14.431, respectively. The generated data's mean value of 377 is quite near to the historical data's mean value of 380.7 the same is true for the covariance and standard deviation, which for the historical and anticipated data are 177.3 and 0.4836, respectively, and 182.3 and 0.4836.The RMSE value which is 0.34 for the historical and forecast data was found to be an acceptable value indicating that the ARMA (1,1) model is a suitable model for generating data, and the generated data for another 21 years after 2023 is highly accurate and reliable.