A case study of sedimentation problems of Wadi Arbaat's dams reservoirs

Taha, Abubakr Taha Bakheit,Aldrees, Ali Techno-Press 2021 Advances in nano research Vol.11 No.5

The proper management of reservoir sedimentation is of critical importance for the sustainable development of surface water resources. Dams' reservoirs are losing their ability storage due to sedimentation processes worldwide. These losses vary from one reservoir to another depending on the characteristics of the watershed and water streams. Therefore, the performance of reservoirs is incredibly vulnerable. The area surrounding Red Sea State is under arid and semi-arid condition, and immensely suffering from a shortage of safe and reliable drinking water supplies. Wadi Arbaat is the primary source of water supply in Port Sudan city. Valleys mostly surround the Red Sea State and Wadi Arbaat suffer from a severe decline with the steep slope of 6-10 m/km. Therefore, the Wadi carries large quantities of sediments, which deposit in dams' reservoirs during the flood periods. The siltation strongly influences these dams and their reservoirs suffer from serious problems represented by increasing silting level and shortage in storage capacities. Consequently, this study aims to investigate the current situation and problems of the three existing dams and make a proper decision with a comprehensive and specific vision in the future. The main problems caused by reservoir sedimentation in the Red Sea Mountains are described as a reduction in the storage capacities, and entry of sediments into control structures such as sluice gates. The problems are further exacerbated as there is no guidance on the decision supports tool that is needed to underpin silting in the flood period and water resources management in these steep slope areas. The sedimentation processes, problems and changes of dam operation are discussed in this paper.

Effects of a Static Synchronous Series Compensator (SSSC) Based on a Soft Switching 48-Pulse PWM Inverter on the Power Demand from the Grid

Taha Selim Ustun,Saad Mekhilef 전력전자학회 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.1

In this paper the effects of a Static Synchronous Series Compensator, which is constructed with a 48-pulse inverter, on the power demand from the grid are studied. Extensive simulation studies were carried out in the MATLAB simulation environment to observe the compensation achieved by the SSSC and its effects on the line voltage, line current, phase angle and real/reactive power. The designed device is simulated in a power system which is comprised of a three phase power source, a transmission line, line inductance and load. The system parameters such as line voltage, line current, reactive power Q and real power P transmissions are observed both when the SSSC is connected to and disconnected from the power system. The motivation for modeling a SSSC from a multi-pulse inverter is to enhance the voltage waveform of the device and this is observed in the total harmonic distortion (THD) analysis performed at the end of the paper. According to the results, the power flow and phase angle can be controlled successfully by the new device through voltage injection. Finally a THD analysis is performed to see the harmonics content. The effect on the quality of the line voltage and current is acceptable according to international standards.

Gallbladder-associated hospital admission and cholecystectomy rates across Australia and Aotearoa New Zealand (2004–2019): Are we over-intervening?

Taha Mollah,Harry Christie,Marc Chia,Prasenjit Modak,Kaushik Joshi,Trived Soni,Kirby R. Qin 한국간담췌외과학회 2022 Annals of hepato-biliary-pancreatic surgery Vol.26 No.4

Incidence of apical crack formation and propagation during removal of root canal filling materials with different engine driven nickel-titanium instruments

Taha Özyürek,Vildan Tek,Koray Yılmaz,Gülşah Uslu 대한치과보존학회 2017 Restorative Dentistry & Endodontics Vol.42 No.4

Objectives: To determine the incidence of crack formation and propagation in apical root dentin after retreatment procedures performed using ProTaper Universal Retreatment (PTR), Mtwo-R, ProTaper Next (PTN), and Twisted File Adaptive (TFA) systems. Materials and Methods: The study consisted of 120 extracted mandibular premolars. One millimeter from the apex of each tooth was ground perpendicular to the long axis of the tooth, and the apical surface was polished. Twenty teeth served as the negative control group. One hundred teeth were prepared, obturated, and then divided into 5 retreatment groups. The retreatment procedures were performed using the following files: PTR, Mtwo-R, PTN, TFA, and hand files. After filling material removal, apical enlargement was done using apical size 0.50 mm ProTaper Universal (PTU), Mtwo, PTN, TFA, and hand files. Digital images of the apical root surfaces were recorded before preparation, after preparation, after obturation, after filling removal, and after apical enlargement using a stereomicroscope. The images were then inspected for the presence of new apical cracks and crack propagation. Data were analyzed with χ2 tests using SPSS 21.0 software. Results: New cracks and crack propagation occurred in all the experimental groups during the retreatment process. Nickel-titanium rotary file systems caused significantly more apical crack formation and propagation than the hand files. The PTU system caused significantly more apical cracks than the other groups after the apical enlargement stage. Conclusions: This study showed that retreatment procedures and apical enlargement after the use of retreatment files can cause crack formation and propagation in apical dentin.

Pressure effects on dynamics behavior of multiwall boron nitride nanotubes

Taha Talebian 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.1

The dynamic behavior of Multiwall boron nitride nanotubes (MWBNNTs) is investigated by employing multiple elastic shells model. The influences of van der Waals interactions on layers are shown as nonlinear functions of the interlayer distance of MWBNNTs. Governingequations are solved by using the developed finite element method and by employing time history diagrams. The radial wavespeed from the outermost layer to the innermost layer is computed. The effects of geometrical factors such as diameter-to-thickness ratioon dynamic behavior of MWBNNTs are determined. The magnification aspects of MWBNNTs are computed, and the effects of surroundingpressures on wave speed and magnification aspect of MWBNNTs are discussed.

Electromagnetic Wave Absorption Properties of Core-Shell Ni/CuSiO3 Nanocomposite

Taha Latif,Rambabu Kuchi,Jong-Ryul Jeong 한국자기학회 2020 한국자기학회 학술연구발표회 논문개요집 Vol.30 No.1

Further validation to the variational method to obtain flow relations for generalized Newtonian fluids

Taha Sochi 한국유변학회 2015 Korea-Australia rheology journal Vol.27 No.2

We continue our investigation to the use of the variational method to derive flow relations for generalized Newtonian fluids in confined geometries. While in the previous investigations we used the straight circular tube geometry with eight fluid rheological models to demonstrate and establish the variational method, the focus here is on the plane long thin slit geometry using those eight rheological models, namely: Newtonian, power law, Ree-Eyring, Carreau, Cross, Casson, Bingham and Herschel-Bulkley. We demonstrate how the variational principle based on minimizing the total stress in the flow conduit can be used to derive analytical expressions, which are previously derived by other methods, or used in conjunction with numerical procedures to obtain numerical solutions which are virtually identical to the solutions obtained previously from well established methods of fluid dynamics. In this regard, we use the method of Weissenberg-Rabinowitsch- Mooney-Schofield (WRMS), with our adaptation from the circular pipe geometry to the long thin slit geometry, to derive analytical formulae for the eight types of fluid where these derived formulae are used for comparison and validation of the variational formulae and numerical solutions. Although some examples may be of little value, the optimization principle which the variational method is based upon has a significant theoretical value as it reveals the tendency of the flow system to assume a configuration that minimizes the total stress. Our proposal also offers a new methodology to tackle common problems in fluid dynamics and rheology

The 100 top-cited articles on scrub typhus: a bibliometric analysis

Taha Hussein Musa,Wei Li,Joseph Kawuki,Pingmin Wei 질병관리본부 2021 Osong Public Health and Research Persptectives Vol.12 No.2

Objectives: The aims of this study were to analyze the characteristics of the 100 top-cited articles on scrub typhus (ST), and to assess the present research landscape and future research directions using bibliometric analysis. Methods: Web of Science was used to conduct a bibliometric analysis of the 100 top-cited articles on ST. The articles were analyzed by publication year, number of citations, document type, journals, keywords, institutions, country of origin, and authorship. Results: The top 100 articles on ST were published between 1945 to 2017. The number of citations ranges from 39 to 227 and the interquartile range was 35.5. The United States published the highest number (n=21) of articles. Mahidol University was the most prolific institution in terms of articles (n=14). The American Journal of Tropical Medicine and Hygiene was the journal with the most articles (n=14), and Paris DH was the most productive author in terms of the Hirsh-index, which was 10 for that author. The study revealed a significant correlation between the total number of citations and the number of authors (r=0.668, p<0.001), number of institutions (r=0.692, p<0.001), number of years since publication (r=0.869, p<0.001), and number of countries involved (r=0.963, p<0.001). Conclusion: The findings of this study provide landmarks in the publication and citation frequency of the most influential articles on ST. In addition, this study provides useful information for readers and health policy-makers in evaluating the literature on ST.

The effect of root canal preparation on the surface roughness of WaveOne and WaveOne Gold files: atomic force microscopy study

Taha Özyürek,Koray Yılmaz,Gülşah Uslu,Gianluca Plotino 대한치과보존학회 2018 Restorative Dentistry & Endodontics Vol.43 No.1

Objectives To examine the surface topography of intact WaveOne (WO; Dentsply Sirona Endodontics) and WaveOne Gold (WOG; Dentsply Sirona Endodontics) nickel-titanium rotary files and to evaluate the presence of alterations to the surface topography after root canal preparations of severely curved root canals in molar teeth. Materials and Methods Forty-eight severely curved canals of extracted molar teeth were divided into 2 groups (n = 24/each group). In group 1, the canals were prepared using WO and in group 2, the canals were prepared using WOG files. After the preparation of 3 root canals, instruments were subjected to atomic force microscopy analysis. Average roughness and root mean square values were chosen to investigate the surface features of endodontic files. The data was analyzed using one-way analysis of variance and post hoc Tamhane's tests at 5% significant level. Results The surface roughness values of WO and WOG files significantly changed after use in root canals (p < 0.05). The used WOG files exhibited higher surface roughness change when compared with the used WO files (p < 0.05). Conclusions Using WO and WOG Primary files in 3 root canals affected the surface topography of the files. After being used in root canals, the WOG files showed a higher level of surface porosity value than the WO files.

Epidemiological trends of gallbladder cancer in Australia between 1982 to 2018: A population-based study utilizing the Australian Cancer Database

Taha Mollah,Marc Chia,Luke C. Wang,Prasenjit Modak,Kirby R. Qin Korean Association of Hepato-Biliary-Pancreatic Su 2022 Annals of hepato-biliary-pancreatic surgery Vol.26 No.3

Backgrounds/Aims: Gallbladder cancer (GBC) is a rare neoplasm. The epidemiology of GBC has not been updated in Australia for over five decades. Methods: Data of all Australian patients diagnosed with GBC at any age from 1982 to 2018 were identified from the Australian Cancer Database. Age-standardized rates were calculated and joinpoint analysis was performed to ascertain the trends of incidence and mortality of GBC. Results: Between 1982 and 2018, there were 22,745 cases of GBC and 11,054 GBC-related deaths in Australia. There were three distinct periods showing changed incidence. Period 1 (1982–1995) was stable. Period 2 (1996–2006) showed reduced incidence in females (3.6 to 2.8/100,000; p < 0.01) and all Australians (3.7 to 2.8/100,000, p < 0.01). Period 3 (2006–2017) demonstrated significantly increased incidence in all groups (males: 2.7 to 4.0/100,000, p < 0.01; females: 2.8 to 3.5/100,000, p < 0.01; all Australians: 2.8 to 3.7/100,000, p < 0.01). Incidence between females and males had declined from 1.10 : 1 in 1982 to 0.87 : 1 in 2017. There was a 71% reduction in mortality (3.1 to 0.9/100,000; p < 0.01). Median age at diagnosis increased from 69.7 to 74.3 years for females and from 67.2 to 73.3 years for males. Increasing incidence in the 6th to 8th decade of life in males, compared to previous years, was noted. Conclusions: Incidence, mortality, sex, and age of GBC have significantly changed in Australia since 1982. Rising incidence of GBC in Australia warrants further investigation.