Ain Shams Engineering Journal最新文献

The position and depth of a scour hole around a bridge abutment are the important design parameters. The existing models have been mostly developed for steady flows, whereas real-life abutments often fail due to intrinsically unsteady flood streams. This study used nine hydrographs with different durations and skewness values and evaluated the ultimate scour depth and temporal scour depth variations for a rectangular abutment using the precise underwater image recording devices and then image processing method. Moreover, an eco-friendly permeable spur dike was employed to protect the abutment for the first time, and the testes were re-performed in the presence of the permeable spur dike. Although the hydrograph skewness had no significant effect on the ultimate scour depth, scour variations are dependent on the skewness of the hydrograph. The scour depth increased by up to 17% after the time of the peak flood, and then its variations became highly smaller, with the rising limb having a larger effect than the falling limb on the scour depth. Finally, equations were developed to calculate the scour depth during hydrographs. These equations enable bridge designers to have deeper insights into scouring around abutments during a flood and provide more reliable and economical estimates in the design of the abutment foundation size and depth.

This paper presents a unified theoretical framework to investigate the performance of an integrated unmanned aerial vehicle (UAV)-backscatter communication (BackComm) system for internet of things (IoT) sensor network applications. In this system, UAV can work as a carrier emitter and data collector to/from a group of passive sensor nodes, whose operation is based on the principle of backscattering technology. Exact and asymptotic mathematical equations are obtained to describe the system performance, such as outage probability, effective capacity, and average BER over a correlated Nakagami-m fading channel, assuming that forward and backscatter links are correlated. In addition, an optimal data collection location for the UAV is also explored by decreasing the euclidean distance between the UAV and the sensor nodes. The numerically simulated results show that the impact of channel correlation degrades the system performance significantly, which can be improved when the fading parameter m increases. Besides, by carefully selecting the position of the UAV, we can further enhance the overall system performance.

Attractors with multiple wings and many scrolls remain captivating for the number and variety of non-linear bifurcations they display. Then, other features related to these attractors like hyper-chaos, fractal, hidden attractor, strange attractor are also significant. This paper analyzes and implements another important attractors' feature, related to generating their mirror symmetrical projections which also conserve the original properties. The generation of that mirroring process is possible thanks to the perturbation with the duality-symmetrical operator ϵ and the mirror conversion function λ, that have been incorporated into a variable order four dimensional system of chaotic attractors with many scrolls (CAMS). We first solve the model numerically and analyze the committed error then, we study the system's state of disorder, stability and randomness. Numerical simulations are performed and show existence of the model's CAMS in their mirroring structure, where the mirror images share identical properties. Lastly, a programmed circuit implementation is done making used of a digital-to-analog converter (DAC) and a Field Programmable Gate Array (FPGA) board. The obtained digital outputs via the Rigol digital oscilloscope (RDO) correspond to the intended outcomes, those found in the analytical-numerical part of the work.

Wireless charging for electric vehicles has an alignment problem that affects transmission efficiency. Studies aimed to reduce alignment issues by employing techniques such as varying coil structures, altering the charging system topology or frequency, and implementing phase shift control. A new work allowed for an alignment tolerance of 220 cm on the x-axis, 110 cm on the y-axis, and 30 cm on the z-axis. Eight scenarios were analysed for stable solutions, mutual inductance (M) and transmission power of electric vehicles. The study resolved the misalignment and increased transmission power by 28.8 %, 68.7 %, and 67.8 % for Scenarios 1–3 compared to the unaligned situation. In Scenarios 4–7, the proposed system can transfer power despite being in the unaligned state. The power transfers are 983 W, 968 W, 1006 W and 971 W, respectively. In Scenario 8, power transmission is impossible with or without the proposed system because of the long distance between coils.

Increasing the efficiency and sustainability of transportation is a key topic for both automakers and academic researchers. The noise, vibration, and harshness (NVH) of electric and hybrid electric vehicles affect their occupants, which is essential if these vehicles are to be commercially successful. Furthermore, noise pollution in urban areas is a growing concern, and vehicle noise is a major contributor to this problem. Vehicle noise can adversely affect the health and well-being of passengers and pedestrians. A concise, state-of-the-art review of NVH sources and suppression techniques for electric vehicles (EVs), hybrid electric vehicles (HEVs) and internal combustion engine (ICE) vehicles is presented in this paper. NVH is covered for both conventional ICE-powered vehicles as well as electric and hybrid vehicles. Furthermore, the research also addressed NVH sources such as the interior, powertrain, road-tires, suspension, brakes, wind-structure, power-coupling devices, clutches and transmissions, and electric motors. Additionally, the study identifies potential future research areas and NVH sources that need further investigation. By doing so, automobiles will be able to provide a more comfortable ride. According to the study, traditional ICE-powered vehicles’ powertrains have a considerable adverse effect on NVH at low speeds. However, NVH resulting from the interaction between the road tire and the wind structure becomes more prominent as the vehicle accelerates. The primary source of NVH in EVs is the power-coupling device, particularly in HEVs. In addition, clutch and transmission noise is present when operating at low speeds with heavy loads. In spite of this, road-tire and wind-structure interactions are the primary sources of NVH at high vehicle speeds, just as they are in conventional ICE-powered vehicles.

This paper presents a method for selecting pilot points used in secondary voltage control of active distribution networks. A unique formulation for pilot point selection is presented as a multi-objective stochastic optimization problem solved using differential evolution. The pilot point selection method considers multiple operating cases with different combinations of solar photovoltaic generation, loads, and electric vehicle uncertainties. The proposed methodology is applied to the IEEE 33 bus test system and a large Australian distribution feeder while observability, controllability, and robustness metrics are used to compare the proposed method against existing methods. Compared with the existing pilot point selection approaches, it is found that the proposed method obtains the most observable, controllable, and robust set of pilot points, making the method effective for the optimal selection of pilot points used in secondary voltage control of active distribution networks.

The substructure method based on the frequency response function is an effective method to solve the frequency response function of locally variable structure, which is especially suitable for the design of vibration absorber parameters in the inertial navigation vibration reduction system. In this paper, one inertial navigation vibration reduction system was taken as an example, and its random dynamic response model was established by using the substructure method based on the frequency response function. Then the influence of the variation of the stiffness and damping parameters of the vibration absorber on the random vibration response of the system was analyzed. The results showed that: (1) it is difficult to effectively reduce the vibration response of inertial navigation vibration reduction system by simply changing the axial stiffness of the vibration absorber, but probably increasing the response in other directions; (2) the vibration response of the inertial navigation vibration reduction system will decrease with the increase of damping, which indicates that the response of the inertial vibration reduction system mainly includes medium and low frequency. The numerical example shows that the proposed method is suitable for the optimization of vibration absorber parameters in the inertial navigation system.

Two laboratory-scale steel tube and concrete four-leg lattice prototypes were designed for use as wind turbine towers using optimized gimbaled wrapped ball-sheet- type nodes. Repeated load tests were performed on the prototype tower for several weeks to evaluate its damage modes, strength, stiffness, etc., and the numerical simulation was conducted. The results showed that the damage mainly included strength damage to the pylon, flexural damage to the top cross web and cracks at the bottom of the loading plate welded to the steel pipe. In addition, the web-tower stiffness ratio and ultimate bearing capacity of the tower improved to varying degrees. It is recommended that the web-tower stiffness ratio be between 0.05 and 0.07. When the connection between the ball column and the node plate changes from a high-strength bolt connection to a welded connection, the ultimate load-carrying capacity of the tower model increases by an average of approximately 8%.

This manuscript is dedicated to the comprehensive exploration of solitary wave solutions for the fractional couple Drinfeld-Sokolov-Wilson equation, which is a versatile mathematical model that finds applications in various branches of physics, including nonlinear acoustics and fluid mechanics. The new extended direct algebraic method is employed as a powerful analytical tool throughout the study. A general algorithm that is essential for the analysis of the models stated is introduced in the manuscript. The travelling wave transformation is used to convert these models into ordinary differential equations, which makes the analysis easier to handle. The study yields a diverse set of solitary wave solutions in the form of dark, dark-bright, bright-dark, singular, periodic, mixed trigonometric, and rational forms. Also, by using the Hamiltonian property, validation of the solutions is conducted, which confirms the accuracy and stability of segregated solitary wave solutions. The discovered results are provided not only in numerical form but also with insightful physical interpretations, which contribute to a deeper comprehension of the complex dynamics these mathematical models depict. The utilization of the new extended direct algebraic method and the broad spectrum of obtained solutions contribute to the depth and significance of this research in the field of nonlinear wave equations.

Graph operations enable the modification and transformation of graphs, enhancing data representation as well as effectiveness in fields such as computer science, mathematics, and data analysis. Super line graph operations are a concept of advanced graph theory that is used in advanced mathematics and computer science. They are used to solve specific mathematical problems, especially in graph theory and Combinatorics. Topological numbers are numerical values connected with graph structures that are used to analyze structural characteristics and solve problems in fields such as chemistry and mathematics. They are important for simplifying complex data and enabling quantitative analysis. The general Randić number of some super line graph operations of number two with a three-diameter is investigated in this study. The pendant vertices are inserted without disturbing their diameter. Seven graphs of order five, each with a diameter of three, can be used to create twenty-three generalized super line graphs.