http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15590 Thu, 23 Apr 2026 07:07:29 GMT 2026-04-23T07:07:29Z http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15637 DETERMINATION OF RADON GAS LEVELS IN THE AIR IN THE FACULTY BUILDING (BİTLİS) Bal, Sultan Şahin; Koç, Yonca Dervişoğlu Living things are exposed to internal and external natural radiation throughout their lives. Natural radiation consists mostly of cosmic rays and terrestrial radiation sources containing many radioisotopes. While uranium, thorium and potassium are the main radionuclides that constitute terrestrial natural radiation sources; radon is a radioactive gas that occurs naturally by the decay of uranium found in soil, rocks and water. People are mostly exposed to natural radiation due to building construction materials and indoor radon concentration. In this study, measurement of radon gas activity concentration levels in the air in Bitlis Eren University Faculty of Science and Letters building was made using an active radon measurement detector (AlphaGUARD). As a result of these measurements; The average radon activity concentration was determined as 41.13 Bq/m3. When the measurement results are compared with the limit values; It has been determined that there is no risk to health. Annual effective dose equivalent, AEDE, (average 0.889 mSv/y) and excess lifetime cancer risk, ELCR, (average 3.545) parameters were calculated using radon activity concentration values. Mon, 01 Jan 2024 00:00:00 GMT http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15637 2024-01-01T00:00:00Z http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15636 EXERGO-ENVIRONMENTAL SUSTAINABILITY ASSESSMENTS OF ORGANIC RANKINE CYCLE PLANTS POWERED BY A TYPICAL ABANDONED OIL WELL Agberegha, Larry Orobome; Oyekale, Joseph Economic and technical factors often force players in the oil and gas sectors to abandon oil wells with significant but minimal energy contents. To promote energy efficiency, efforts are ongoing to explore viable means of recovering such residual energy, basically as geotherms, for power generation. However, there are sparse studies in the literature that assess the exergoenvironmental sustainability potentials of power generation from ORC using abandoned oil wells as the primary energy source, thereby necessitating this study. The exergetic sustainability and exergo-environmental performance of non-recuperative and recuperative organic Rankine cycle (ORC) plants were assessed in this study for the production of electricity from abandoned oil wells. The geomechanical properties of a typical oil well in Nigeria were employed as inputs into an established COMSOL model to determine the thermal profile of the heat source. For the ORC plant, the mass, energy, and exergy balance equations defined by the Thermodynamics laws were implemented in MATLAB. Also, MATLAB was adopted for computing the exergetic sustainability and exergo-environmental metrics for the individual components and the entire system. Results showed that the condenser exhibited the least exergo-environmental sustainability for both ORC schemes assessed, meaning that it contributed the most to energy wastages among the system components. Furthermore, results showed that the exergo-environmental impact rates of the condenser are highest in both cases. Generally, results showed that the inclusion of a recuperator would improve the exergy-based environmental sustainability of the ORC plant. Specifically, the overall rate of exergo-environmental impact would decrease from around 86 Pt/h to about 76 Pt/h, amounting to approximately 13% decrease. Mon, 01 Jan 2024 00:00:00 GMT http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15636 2024-01-01T00:00:00Z http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15634 TWIN GHOSTS: EVIL TWIN ATTACKS IN WIRELESS NETWORKS AND DEFENSE MECHANISMS Kara, İlker With the increasing adoption of wireless network technologies, a variety of attacks targeting these networks have emerged, posing significant threats to user security. One prominent type of attack is the evil twin attack, which involves the creation of fake access points, often referred to as "evil twins." In this type of attack, a malicious actor sets up a fake access point (AP) designed to closely resemble a legitimate one, thereby deceiving users into believing it is trustworthy. By exploiting these fake APs, attackers can capture user credentials and gain unauthorized access to sensitive information, potentially leading to financial exploitation or system breaches. Due to the covert nature of evil twin attacks, they can be highly effective without the users' awareness. In this study, explores the risks posed by evil twin attacks and investigates defense strategies to address the security challenges in wireless networks. To achieve this, a scenario involving an evil twin attack is developed and analyzed. In this scenario, an attacker establishes a fake wireless access point in a café or public area near the targeted institution, replicating the institution's network name and security settings to trick users into connecting to the malicious network. This study underscores the potential impacts of such attacks and outlines critical measures that both users and institutions should implement to safeguard against these threats. Mon, 01 Jan 2024 00:00:00 GMT http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15634 2024-01-01T00:00:00Z