Emergency Obstetrical Hysterectomy

This study was designed to determine the incidence, indications and complications of emergency obstetrical hysterectomy. The cases were analyzed from January 2003 to December 2008 in the obstetric unit of Fatima Hospital, Baqai Medical University, Karachi. The Demographic and clinical variables were obtained from the maternal records. Incidence of emergency obstetrical hysterectomy was found out to be 1:238 deliveries. Out of these 6(40%) of patients were in the age group between 31-35 years. Average age was 31years. Multiparous patients were 7(46.6%) and grand multiparous were 6(40%) with mean parity of 5. The most common indication leading to obstetrical hysterectomy was Atonic uterus causing postpartum hemorrhage in 7(46.6%) of patients. Ruptured uterus was responsible for this procedure in 2(13.3%) patients. Regarding complications, deep venous thrombosis developed in 1(6.6%) patient. The maternal deaths occurred in 3(20%) patients. The incidence of emergency obstetrical hysterectomy is not very much high. Majority of the patients were referred by traditional birth attendants (TBA’s) with complications of labor and delivery. To further reduce the incidence, education of TBA’s and early referral along with community awareness are essential

Two phase simulation of solar still in the presence of phase change materials in its bottom and aluminum nanoparticles in the water

DATA AVAILABILITY : Data will be made available on request.Please read abstract in the article.The Deanship of Scientific Research at Najran University.https://www.elsevier.com/locate/csitehj2024Mechanical and Aeronautical EngineeringSDG-09: Industry, innovation and infrastructur

Machine Learning-Based Approach for Modeling the Nanofluid Flow in a Solar Thermal Panel in the Presence of Phase Change Materials

Considering the importance of environmental protection and renewable energy resources, particularly solar energy, the present study investigates the temperature control of a solar panel using a nanofluid (NFD) flow with eco-friendly nanoparticles (NPs) and a phase change material (PCM). The PCM was used under the solar panel, and the NFD flowed through pipes within the PCM. A number of straight fins (three fins) were exploited on the pipes, and the output flow temperature, heat transfer (HTR) coefficient, and melted PCM volume fraction were measured for different pipe diameters (D_Pipe) from 4 mm to 8 mm at various time points (from 0 to 100 min). Additionally, with the use of artificial intelligence and machine learning, the best conditions for obtaining the lowest panel temperature and the highest output NFD temperature at the lowest pressure drop have been determined. While the porosity approach was used to model the PCM melt front, a two-phase mixture was used to simulate NFD flow. It was discovered that the solar panel temperature and output temperature both increased considerably between t = 0 and t = 10 min before beginning to rise at varying rates, depending on the D_Pipe. The HTR coefficient increased over time, showing similar behavior to the panel temperature. The entire PCM melted within a short time for D_Pipes of 4 and 6 mm, while a large fraction of the PCM remained un-melted for a long time for a D_Pipe of 8 mm. An increase in D_Pipe, particularly from 4 to 6 mm, reduced the maximum and average panel temperatures, leading to a lower output flow temperature. Furthermore, the increased D_Pipe reduced the HTR coefficient, with the PCM remaining un-melted for a longer time under the panel.Deanship of Scientific Research at Najran UniversityPeer Reviewe

Numerical Analysis of the Effect of Nanoparticles Size and Shape on the Efficiency of a Micro Heatsink

In this paper, two novel micro heat sinks (MHSs) were designed and subjected to thermal analysis using a numerical method. The fluid used was Boehmite alumina–water nanofluid (NFs) with high volume fractions (VOFs). Studies were conducted to determine the influence of a variety of nanoparticle (NP) shapes, such as platelet brick, blade, cylinder, and Os. The heatsink (HS) was made of copper, and the NFs entered it through the middle and exited via four outlets at the side of the HS. The finite element method was used to simulate the NFs flow and heat transfer in the HSs. For this purpose, Multi Physics COMSOL software was used. The maximum and middle values of HS temperature (T-MAX and T-Mid), thermal resistance (TH-R), heat transfer coefficient (h), FOM, etc., were studied for different NP shapes, and with Reynolds numbers (Re) of 300, 1000, and 1700, and VOFs of 0, 3, and 6%. One of the important outcomes of this work was the better thermal efficiency of the HS with rectangular fins. Moreover, it was discovered that a rise in Re increased the heat transfer. In general, adding NPs with high VOFs to MHSs is not appropriate in terms of heat. The Os shape was the best NP shape, and the platelet shape was the worst NP shape for high NPVOF. When NPs were added to an MHS, the temperature of the MHS dropped by an average of 2.8 or 2.19 K, depending on the form of the pin-fins contained inside the MHS (circular or square). The addition of NPs in the MHS with circular and square pin-fins enhanced the pressure drop by 13.5% and 13.3%, respectively, when the Re = 1700.National Research Priorities funding programPeer Reviewe

Investigating the Effect of Tube Diameter on the Performance of a Hybrid Photovoltaic–Thermal System Based on Phase Change Materials and Nanofluids

The finite element (FEM) approach is used in this study to model the laminar flow of an eco-friendly nanofluid (NF) within three pipes in a solar system. A solar panel and a supporting phase change material (PCM) that three pipelines flowed through made up the solar system. An organic, eco-friendly PCM was employed. Several fins were used on the pipes, and the NF temperature and panel temperature were measured at different flow rates. To model the NF flow, a two-phase mixture was used. As a direct consequence of the flow rate being raised by a factor of two, the maximum temperature of the panel dropped by 1.85 °C, and the average temperature dropped by 1.82 °C. As the flow rate increased, the temperature of the output flow dropped by up to 2 °C. At flow rates ranging from low to medium to high, the PCM melted completely in a short amount of time; however, at high flow rates, a portion of the PCM remained non-melted surrounding the pipes. An increase in the NF flow rate had a variable effect on the heat transfer (HTR) coefficient.The Deanship of Scientific Research at Najran UniversityPeer Reviewe

Impact of five obstacles with constant temperatures on the mixed convection flow of water/copper nanofluid in a rectangular cavity with a magnetic field

DATA AVAILABILITY : Data will be made available on request.Please read abstract in the article.The Deputy for Research and Innovation Ministry of Education, Kingdom of Saudi Arabia under the Institutional Funding Committee at Najran University, Kingdom of Saudi Arabia.https://www.elsevier.com/locate/rinphj2024Mechanical and Aeronautical EngineeringSDG-09: Industry, innovation and infrastructur

Thermal management of a prismatic lithium battery pack with organic phase change material

BACKGROUND : This article examines a T-shaped lithium-ion battery pack (BPC) consisting of six prismatic cells using the finite element method (FEM). An optimal model is introduced for batteries’ thermal management (THMT) by changing the position of the inlets and outlets. METHODS : The outlet is where the fully developed airflow leaves, and the walls use the no-slip boundary condition. The batteries are placed in an enclosure filled with phase change material (PCM) to create temperature uniformity on the batteries. The hydrodynamic and thermal modeling of airflow and the melting and freezing of PCM are performed in this study using the COMSOL program. SIGNIFICANT FINDINGS : The results demonstrate that the batteries’ maximum temperature (TMX) changes by changing the location of the inlets. Changing the position of inlets also affects the melting and freezing of the PCM, and better temperature uniformity on the batteries may be achieved using some models. The M4 model, in which the inlet and outlet are on the left and right sides, and an outlet is in the center, is the most appropriate model for industrial applications.The Deputy for Research and Innovation Ministry of Education, Kingdom of Saudi Arabia under the Institutional Funding Committee at Najran University, Kingdom of Saudi Arabia.https://www.journals.elsevier.com/journal-of-the-taiwan-institute-of-chemical-engineersam2024Mechanical and Aeronautical EngineeringSDG-07:Affordable and clean energySDG-09: Industry, innovation and infrastructur

Optimization of window solar gain for a building with less cooling load

DATA AVAILABILITY: No data was used for the research described in the article.Considering solar gain through the window (SGW), this study investigated the effects of installing shading on cooling load. Approving energy analysis for the base building (without shading), the cooling, heating, and annual energy demand were calculated. The best window angle and the best shading projection were obtained using the genetic algorithm. For the yearly minimum energy demand scenario, it was found that the window should be placed in the south direction, accompanied by the shading project with a maximum length of 20 cm. The results of the genetic algorithm revealed that for windows at the angle of 75–90°, the positive shading effects on annual energy demand become maximum. In this case, the shading reduces the yearly energy consumption by 3.1 %. The optimization showed that the shades have the best results for reducing the cold load for windows that are located in the azimuth angle between 135 and 180°.The Deanship of Scientific Research at Najran University under the Distinguish Research Funding Program.https://www.elsevier.com/locate/csitehj2024Mechanical and Aeronautical EngineeringSDG-07:Affordable and clean energ

Numerical investigation of the effect of rectangular and semicircular cavities filled with phase change materials installed on the solar wall

The use of alternative energy sources, particularly solar energy, in buildings is rising and spreading around the globe. In this paper, a solar wall is analyzed using a numerical method. On the wall, a number of obstacles are placed in two shapes, rectangular (REC) and semicircular (SEC). The cavities are filled with organic phase-change materials. This study was performed in 7 h in the absence of solar radiation on the wall for different dimensions of obstacles in 5 different modes. Various temperatures have been investigated, including exhaust air temperature (TAR), Trombe wall temperature (TWL), and mean volume % of molten PCM in cavities. COMSOL software is used to carry out this numerical study. The results of this study showed that the use of SECs compared to RECs causes the TWL to be higher. In the most extreme case, at a 16 cm aspect ratio, the use of SECs gives a 2.1 °C increase in TWL relative to the REC one. The outlet TAR is also increased by the usage of SECs. The use of larger dimensions of the cavities has increased the TAR leaving the wall so that the TAR after 7 h of the absence of solar radiation, in the most significant case of SECs, was more than 295.5 K. The use of SECs also increases the PCM freezing time. In the largest case of cavities, using SECs increases the freezing time by 15 min compared to RECs.Open access funding provided by University of Pretoria. The authors are thankful to the Deanship of Scientific Research at Najran University for funding this work under the Research Priorities and Najran Research funding program.https://www.springer.com/journal/11356hj2024Mechanical and Aeronautical EngineeringSDG-07:Affordable and clean energ