Results in Engineering最新文献

The conventional closed and open jet tunnels suffer from various adverse blockage effects that alter the flow conditions generating erroneous results when larger than allowable blockage models are tested. The maximum acceptable blockage is limited to 25 % for an open jet tunnel. The physics behind the inferior blockage capacity and their redressal is investigated. Hitherto, numerical models are developed to rectify the blockage troubles that introduce an additional complex case-based mathematical modeling to reckoning the results. In the current paper novel approach to redesigning the tunnel to solve blockage troubles is investigated that facilitates evading of mathematical techniques and securing accurate results straightforwardly. A hypothetical design incorporating the remedies is proposed, capable of conditioning the flow in a manner that debilitates the adverse effects of solid blockage, wake blockage, jet expansion, etc. The hypothesis is theoretically expounded by the boundary layer and jet flow phenomenon. The modified blower-type open jet wind tunnel constitutes a centrifugal blower, long inlet duct, plenum chamber around the test section, and collector. The modified wind tunnel is tested through experiments executed on four different-sized Savonius rotors creating 10 %, 30 %, 50 %, and 60 % blockage. The static pressure along the contours of the blades of rotors is obtained. The experimental results are juxtaposed with CFD results carried out at free-wind boundary conditions and standard classic experimental results performed in conventional wind tunnel at 11 % blockage. A blockage enhancement of 25 % is achieved by the approach of modification in the design of a conventional open jet wind tunnel.

A catalyst based on zero-valent iron nanoparticles (nZVI) supported by zeolite Y (zeolite Y-nZVI) was synthesized to improve the performance of the heterogeneous electro-Fenton-like process for treating a toxic pesticide wastewater with pH of 6. Central Composite Design (CCD) under Response Surface Methodology (RSM) was applied to design the experiments and find the optimal parameters including time, current intensity, hydrogen peroxide volume (or concentration) and the synthesized catalyst dosage. The results showed that the chemical oxygen demand (COD) removal under the optimal conditions (time of 125 min, current intensity of 272 mA, hydrogen peroxide volume (or concentration) of 0.19 ml (8.102 × 10⁻³ M), and zeolite Y-nZVI catalyst dosage of 1.78 g) was at 83.69 % for treating a wastewater with pH of 6 although this increased to 91.26 % at pH of 3 under the Fenton reactions. In fact, the synthesized catalyst could properly treat wastewater in a pH close to neutral one. Since electro-Fenton is as efficient technique for treating the hazardous pollutants such as pesticide, it can successfully be used by their manufacturing factories. Since it properly works in the acidic pHs, it is not as applied technique for most of industries. Therefore, catalytic electro-Fenton process can be performed in (or near) a neutral pH. Since electro-Fenton is basically associated with iron, a catalyst based on it (such as Fe°) was chosen and supported on an abundant and suitable material such as zeolite. The synthesized catalyst was initially synthesized and characterized, and then successfully applied in the electro-Fenton process to treat a real pesticide containing wastewater obtained from industry.

The reliability and efficiency of electrical power systems are critical for modern industries, which increasingly rely on electric machines and devices. However, power electronic converters add non-linear demands to the electric power distribution systems (EPDS), that can cause power quality (PQ) problems, which could harm electric devices. As a result, EPDS are pointed for the most effective and economical techniques to enhance PQ. Therefore, Dynamic Voltage Restorer (DVR) is employed to maintain voltage stability in modern EPDS. This study focuses on the application of Sliding Mode Control (SMC) in DVRs to protect against voltage dips, enhancing power system sustainability. It details the construction, operation, and control methods of DVRs, comparing the conventional PI-controller with SMC. The arctic puffin optimizer is utilized to get the optimum gains of the PI regulator, and at the same time, it is used to specify the optimal sliding surface required for SMC. A distribution system contains DVR is suggested and implemented utilizing Simulink/MATLAB. The simulation results of the DVR employing SMC and the conventional PI-controller demonstrate a marked improvement in voltage regulation and power quality. Specifically, the SMC-based DVR exhibited a reduction in voltage sag duration and magnitude by approximately 30 % compared to the PI-controller. Additionally, the total harmonic distortion (THD) in the load voltage was reduced by 25 %, indicating a significant enhancement in power quality. These improvements of the enhanced performance of the SMC-based DVR supports the seamless integration of renewable energy sources, which often introduce variability into the power grid.

The development of high performance and eco-friendly composite railway sleepers at a reasonable price is a great challenge for composite railway sleeper manufacturers. The study proposed a railway sleeper concept based on high-performance fibre composites and low-cost waste-based materials to overcome this challenge. In this concept, thin hollow composite tubes are filled with high volume waste-based panels, which are bonded together with cement grout. This study examined the effect of cement grout, grout thickness, panel types, and surface preparation of the panels on the bond behaviour between the panels and cement grout. It also investigated the bending behaviour of manufactured railway sleepers by evaluating the effects of filling hollow tubes, the orientation of the infill panels, and the types of infill materials. Results indicate that the proposed concept has a high potential for development of high performance and eco-friendly composite railway sleepers at a competitive price due to the incorporation of high volume of waste materials. The results of the study will serve as a guide to the manufacture and design of composite railway sleepers.

Phytochemicals in grape fruit juice have never been considered as potential sources of surface modification, shape modification, and energy storage. In our study, we demonstrate the hydrothermal synthesis of Co₃O₄ nanostructures from grape fruit extracts. X-ray diffraction analysis revealed that Co₃O₄ nanostructures exhibit a cubic phase, while Fourier transform infrared spectroscopy identified several functional groups. An analysis of Co₃O₄ nanostructures using a scanning electron microscope revealed that uniformly distributed nanoparticles of Co₃O₄ were trapped in the carbon content of the spices during calcination. UV–visible spectrometer analysis of Co₃O₄ nanostructures reveals a wide range of optical bands. It was found that one mL of grape fruit juice provided the lowest optical band gap of 2.51 eV for Co₃O₄ nanostructures. Nanostructures of Co₃O₄ were studied under alkaline conditions for use in supercapacitors and oxygen evolution reactions. An aqueous solution containing 1 mL of assisted Co₃O₄ nanostructures exhibited an overpotential of 290 mV at a current density of 10 mA cm⁻² in 1 M KOH. In addition, they showed a Tafel slope of 80 mV dec⁻¹. When dissolved in 3 M KOH electrolyte, grape fruit juice assisted Co₃O₄ nanostructures showed a specific capacitance of 867 F/g at 1.5 A/g in 3 M KOH aqueous solution. A specific capacitance retention percentage of about 101.1 % was achieved after 40000 galvanic charge-discharge cycles. It has been shown that the total photochemistry of biomass waste can be tuned and enhanced to enhance the functional properties of nanostructures derived from rotten grape fruit extract in order to develop functional materials with high performance for a wide range of applications.

The study of dust-acoustic (DA) nonlinear electrostatic waves in dusty plasma is crucial for understanding plasma behavior in both astrophysical and laboratory environments. Dusty plasmas, characterized by the presence of negatively charged dust particles, exhibit complex dynamics influenced by various factors, including nonthermal electron and ion populations following Cairns–Gurevich distributions. This study addresses the problem of understanding wave propagation under these specific conditions by employing a set of fluid hydrodynamic equations for dust fluid, alongside appropriate electron and Cairns–Gurevich ion distributions, to model the dynamics and propagation of DA nonlinear electrostatic waves under specific plasma conditions with negatively charged dust particles. We derived a nonlinear Zakharov–Kuznetsov (ZK) equation to model the evolution of these waves and further transformed it into the nonlinear Schrödinger (NLS) equation to analyze rogue wave formation and identify unstable and stable zones within the plasma. We focused our analysis on the effects of key parameters, such as the nonthermal index, magnetic field strength, negative dust temperature ratio, polarization force, and density ratio, on the behavior of dust-acoustic waves (DAWs). The results demonstrated that soliton waves, explosive waves, and kink waves exhibit distinct behaviors depending on these parameters and the spatial context of Earth's magnetosphere. These findings provide new insights compared to previous studies into the conditions under which these waveforms emerge and evolve, especially in magnetized environments where earlier models were less effective at accurately characterizing or predicting wave behavior. By applying two different analytical methods, a direct integration approach and a generalized Kudryashov method, we expanded our understanding of nonlinear wave phenomena in dusty plasmas. Our results not only advance theoretical knowledge but also have practical implications for interpreting space plasma observations and guiding experimental design in plasma physics research. This study thus contributes to a more comprehensive understanding of plasma dynamics, with potential applications to astrophysical observation and laboratory plasma experimentation.

Light concentrators are widely used to address the challenges of solar radiation's limited energy density. However, traditional light concentrators suffer from bulkiness, higher focal length, low solar acceptance, and cost factor due to the usage of large imaging optics elements. Waveguide-based planar light concentrators (PLC) have been engineered as a solution to these challenges. They work by collecting light at the incident face and channeling it to the lateral face of the waveguides. However, the existing PLC designs mostly consist of multiple optics elements, resulting in the need for precise positioning and point-to-point solar tracking. Addressing these complexities, a new design for waveguide-based PLC is presented. It features a simplified array of skewed V-grooves within an optical slab, essentially creating a single elemental optics. This novel skewed V-groove-based PLC (SV-PLC) introduces a low-concentration (i.e., <10X geometric concentration (GC)) solution that offers high angular acceptance along one axis. The current study aims to establish the novel design concept, validate, optimize, and assess the design through the Ray-tracing simulation. Further, based on the simulation results, a functional prototype was successfully fabricated in PMMA using laser machining. The results of the optical characterization of the SV-PLC showed that the Optical Efficiency (OE) was approximately around half the theoretical OE. Angular-dependent ray trace results showed a lower OE drop (<10 %) for incident angles less than 15°, and a maximum drop of 30 % (for a 10X GC design) for an incident angle of 23.5° (i.e., half the angle shift of the sun through seasons).

Exploring substantial solar irradiation and recuperating excess heat generated during photovoltaic energy conversion is a critical issue. The efficiency of photovoltaic systems (PV) is significantly depend on the increased operating temperatures encountered by solar radiation. One conceivable option for improving the conversion of solar energy is to integrate a photovoltaic (PV) panel with a thermal-electric generator (TEG) material module to create a hybrid system. This study proposed a parallel PV-TEG hybrid module that effectively harvests the maximum solar energy spectrum while maximizing the use of heat generated by the thermoelectric material to improve the overall system efficiency. The proposed module consists of a photovoltaic unit, thermoelectric material module and passive cooling of fluid channels. The aim of this work was to develop a PV-TEG hybrid system and create an energy simulation model in a MATLAB environment to analyze the model's performance under various operational conditions by applying both theoretical and experimental approaches. Findings showed considerable concurrence. At 13:00, when the PV surface temperature was 54 °C, the PV efficiency reached to its lowest value of 12.0 %. Nevertheless, the highest TEG efficiency recorded was 4.7 % at 12:00 h. The efficiency of the TEG module was significantly affected by weather conditions, inlet cooling water temperature, and fluid flow rate in comparison to both the PV efficiency and the thermal efficiency.