×
The submission system is temporarily under maintenance. Please send your manuscripts to
Go to Editorial ManagerCatalytic isomerization is a process used to increase the octane number of light naphtha fraction and thus aids in extending the life of automobile engines. Researchers are still working to prepare more effective and less expensive isomerization catalysts to replace the costly previous catalysts. Ongoing challenges in this field seek to design highly active isomerization catalysts operated under moderate conditions while keeping high branched-isomer selectivity. Heteropolyacids (HPA) have been presented as the most capable substitutes to fulfill the requirements. They are considered bifunctional catalysts that perform dehydrogenation /isomerization followed by hydrogenation because of their firm acidity and redox properties. Some catalytic-isomerization studies were started utilizing HPA in combination with platinum, which significantly improves the selectivity and stability. Thus, HPA-based bifunctional catalysts can provide enough acid and hydrogenation–dehydrogenation sites sufficiently. However, the most ongoing challenge in this field is the poor thermal stability of HPAs, which limits their use at higher temperatures for vapour-phase reactions. This review aims to highlight the recent progress in catalytic isomerization of alkanes using heteropolyacids supported on different carriers, with and without noble metals.
Construction joints are separations between successive concrete pours. They are critical in the building of large concrete structures, since these structures cannot be cast in a single pour. Self-consolidation concrete is a relatively new kind of concrete that is considered suitable for a wide range of construction applications, especially those needing a high early resistance. Certain findings from earlier experimental tests were adopted and analyzed using finite element analysis. ANSYS program was used to analyze the impact of utilizing high strength concrete (fc') and the secondary reinforcement ratio (ρv) on the behavior of reinforced self-consolidating concrete beams having a horizontal construction joint. Nine beams analyzed in this study have the same dimensions (150×180×1200) mm (width× height ×length). Between the two supports, the clear span was 1100 mm. Two-point loads were applied to the simply supported beams during testing. One of the beams acts as a control beam (without a construction joint) and the remaining beams were with horizontal construction joint in the tension zone. The ultimate loads obtained analytically vary by between 3.1% and 7.8 % from those found experimentally. The presence of the horizontal construction joints made the beam less stiff. Utilizing a 70 MPa high strength concrete resulted in a 47.4 % in ultimate load over the experimental value for regular strength concrete (28 MPa). Increasing the ratio of secondary reinforcement (0.01229 to 0.049) resulted in a 10.3% increase in ultimate load magnitude, while decreasing the ratio of secondary reinforcement (0.01229 to 0.0025) with spanning the spacing between stirrups led to a reduction in ultimate load magnitude by 55.8%.
A failing heart can be supported in several ways, including cardiopulmonary bypass pumps (CPB), extracorporeal membrane oxygenators (ECMOs), and other types of auxiliary heart pumps. The intra-aortic-balloon-pump (IABP) is one technique of internal counter-pulsation that supports maintaining the circulatory system It continues to be used as a vascular support device to critically unwell cardiac patients. Many recent studies have focused on the problems of the (IABP) in open-heart surgery, while other researchers concentrated on the positioning and size of the balloon, some of them studied the timing of the balloon's inflation and deflation. this paper has reviewed a brief Introduction, the basic principles of the balloon, how to trigger the balloon pump as well as the use of IABP in Coronary Artery Bypass Graft (CABG), balloon mistiming of inflation and deflation, balloon timing usage within open-heart surgery and finally a balloon position and sizing.
This study aims to review flow-induced vibration one of the repercussions of vibrations is caused by fluid movement. In general, the investigation of the structure of the systems affects the efficiency of the components that construct those systems. This review examined the influence of generated vibrations and internal pressure on fluid transport pipes using theoretical calculations, practical tests, and numerical analysis to identify and test the dynamic behavior of static fluid transport pipes. The experimental study considered the natural frequencies caused by the fluid pressure effect under various stability situations. The flow of all liquids, such as oil, water, gas, air, and vapors, through the pipes, was tested, and the mathematical models were correctly adjusted. All empirical, theoretical, numerical, and analytical research agrees that several approaches exist to develop, modify, and improve these metrics. However, one factor affecting rheological measurements is vibration, which was addressed as needed in the middle of the 20th century due to major discoveries that damage could be rooted in vibration. Established on the determinations, they provided mathematical models paired with pressure and velocity measurements of moving fluids and the influence of produced or uninduced vibration. This study demonstrates that additional empirical investigations, particularly more detailed analytical methodologies, are urgently required to produce better findings.
In this research, we investigate the nonlinear vibration of functionally graded carbon nanotubes (FG-CNTs) for simply supported sandwich cylindrical panels. The sandwich consisting of three layers formed of (FG-CNTs) and isotropic material as (CNT, ALMINUME, CNT). Mechanical properties of the sandwich media are acquired according to a re?ned rule of blend approach. The governing equations were derived using a first-order deformation theory (FOSDT). Four kinds of carbon nanotubes of sandwich cylindrical panels were analyzed. The volume fraction of CNTs is varied. The properties of nonlinear responses and free vibration are studied. The numerical approach employs the fourth-order Runge-Kutta and Galerkine procedure. Which conducted for the dynamic analysis of the panels to present the natural frequencies and non-linear dynamic response expression. The results show that; the natural frequencies and the nonlinear vibration amplitude decrease with the volume fraction and thickness ratio increase. The nonlinear vibration amplitude response increases when increasing the excitation force. The initial imperfection and the elastic foundation have a minor impact on the nonlinear vibration response of the panel. The Pasternak Foundation has a larger impact than the Winkler foundation. The structure formed of FG-CNT present an excellent choice for high-performance of engineering applications.
In Urban cities, services are supported by intelligent applications and are connected to each other through ad hoc networks. Any service can be operated using a compatible of an Internet of Things (IoT) technology. This study focuses on the transportation service and finding a non-cost solution to solve the crossroads congestion that affected people time and money. The Wireless Sensor Networks (WSNs) that are planted on the roads can help in monitoring the roads situation by collecting their data and send them through wireless communication to a traffic management center. In this work two phases of time are considered for a crowded area. Low-cost components are suggested to solve the congestion at the cross roads without the need for reconstruct the roads. IoT device such as smart phone can be wirelessly connected to the Traffic Management Center (TMC), which can analyze the incoming data from WSN and send back the calculated time to the police officer to control the green light long and overcome the standard time installed for all directions. The main idea is to solve the congestion problem in real time by extending the time long of the green traffic light for the road direction with the highest vehicle density. The suggested algorithm was operated on a dataset of 6 days and for the time phase from 7:00-10:00am.
Shallow foundation suffers from considerable settlement, displacement and tilting under earthquakes. This is particularly due to the shaking associated with earthquakes that lead to the generation of horizontal seismic load transferred through the soil to the foundation. Also, liquefaction could take place during the earthquake in the saturated loose sand. To alleviate the detrimental effect of earthquakes, ground improvement is required. This study examines the response of the shallow square foundation rested on loose sand soil reinforced with geogrid reinforcement when subjected to 2023 Turkey earthquake by using a shaking table system. Different number of geogrid layers are installed; (one, two, three and four), also various geogrid configurations were examined which are (straight, trapezoidal and reverse trapezoidal). The acceleration response, settlement, horizontal displacement, rotation and pore water pressure developed in the sand soil and the shallow foundation during 2023 Turkey earthquake has been examined. The settlement and the horizontal displacement, foundation rotation, acceleration and pore water pressure were measured using rope displacement transducers, tilt sensors, accelerometers and pore water transducers respectively. The results showed that the acceleration amplifies when passing through loose sand. The results also indicated that the shallow foundation experienced noticeable settlement, horizontal displacement and rotation when subjected to the seismic loads. On the other hand, the installation of geogrid proved to be effective in controlling the problems associated with earthquakes. The optimum geogrid reinforcement is occurred when three layers of geogrid placed in reverse trapezoidal configuration (3RT) since it gave the best reduction in the acceleration amplification and the highest decrease in the foundation settlement, displacement and tilting which is about (60-66) %. Nevertheless, the effectiveness of geogrid minimizes when the sand soil becomes saturated. In addition, liquefaction occurs during earthquakes especially at the shallower depths because of the decrease in the shear strength of saturated soil.
Flexible and rigid pavements are commonly built for airport pavements to support the moving loads of aircraft during the pavement design life. Airport pavements represent a cornerstone of the aviation world. Their condition profoundly impacts safety, operational efficiency, airport capacity, and financial well-being. These meticulously engineered surfaces must withstand the immense stresses generated by aircraft during takeoff, landing, and taxiing. At the planning stage, the pavement structure, materials, aircraft loads, environmental conditions, and pavement damage models should be evaluated. Comparing with road pavement design, airport pavement structural design is unique in terms of the traffic loads supported by pavements with high load magnitude, significant tire pressure, and dynamic traffic conditions. Over time, deterioration stemming from environmental exposure, aircraft loading, and other factors becomes inevitable. This study aims to explore the various factors influencing airport pavement performance, review the existing methodologies for pavement design and maintenance, and propose enhancements to current practices to ensure long-term durability and safety of airport pavements. This study aims to explore the various factors influencing airport pavement performance, review the existing methodologies for pavement design and maintenance, and propose enhancements to current practices to ensure long-term durability and safety of airport pavements.