Results in Engineering最新文献

Contamination of soil with heavy metals is a threatening global environmental problem. With increasing urbanization, it is very important to design economical and environment-friendly mitigation measures to have pollutant free soil. Phytoremediation is an advancing technique to extract pollutants from soil to achieve eco-sustainability. This study aimed to investigate the combined impact of biochar and silicon on growth attributes of Brachiaria mutica grown in cadmium (Cd) contaminated soil. The biochar was prepared by co-pyrolysis of agricultural left-over biomass (rice husk, bamboo leaves and corn cob in a 1:1:1 ratio) and physio-chemical characters were studied by FTIR, SEM-EDX and proximate analysis. A pot study was conducted to evaluate the potency of biochar and silicon in lowering the Cd uptake by para grass grown under Cd spiked soil. Total 8 treatments were planned by taking 1 % and 2 % biochar with 0.01 % and 0.02 % silicon. The results have shown that treatment 8 (2 % biochar and 0.02 % silicon) exhibited maximum improvement in growth parameters such as shoot length by 2.64-fold and root length by 44.9 %, along with improving the antioxidant defense system of Para grass (CAT by 2-fold and POD by 56.4 %). Application of treatment 8 also decreased Cd concentration in the shoot and root by 48.8 % and 47.4 %, respectively. Treatment 8 was most effective in reducing CaCl₂ extractable Cd in soil up to 56.1 %. Based on this data, treatment 8 was most effectual in suppressing Cd stress. Biochar produced from other agricultural waste material along with Si as inorganic amendment can be used to immobilize other toxic heavy metals at field level. Heavy metals immobilization potential of Si and biochar can be tested by harvesting other grasses and oil seed crop species.

Blade breaking is one of the main issues with industrial process compressors. In this regard, the goal of this study is to look into the potential for droplet formation to see how it can affect the impeller blade breaking (an alloy of 7175 aluminum) of an Olefin plant under the operating conditions (18300–34500 rpm, 286–307 K, 720–969 kPa). At first, the Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) equations of states were used in simulating the turboexpander process and conducting a thermodynamic analysis to investigate the probability of liquid droplet production in the turboexpander. Then, using the Euler-Lagrange approach and the Realizable k-Ɛ turbulence models, the two-phase computational fluid dynamic (CFD) modeling of liquid droplet motion was carried out. Process simulation reveals that the compressor is operated far from two-phase conditions, indicating a negligible probability of droplet formation. The results also show that the area of the blade that had already broken down experiences the highest pressure of the gas stream for each of the three examined rotor speeds and that the gradients of the pressure, stress, and temperature of the gas in the high-pressure (HP) compressor are significantly higher than those in the low-pressure (LP) compressor. Additionally, two-phase modeling of liquid droplets reveals that the presence of condensate has a negligible effect on increasing pressure, shear stress, and other factors affecting the blades. Therefore, under the steady-state conditions, the impact of liquid droplet condensation on the blades can be ignored, and by raising the mass percentage of liquid droplets, the shear stress, pressure, and coefficient of friction all slightly increase. Finally, it can be concluded that, under the operating conditions considered in this work, the droplet production is not the main cause of blade fatigue.

Red mud, known as bauxite residue, is an alkaline solid waste generated during alumina production. Globally, the stockpile of red mud is about 3 billion tons and is increasing at a rate of 150 million tons per year. The global production of red mud is mainly distributed in China (28.2 %), Oceania region (22.4 %), South America (14.6 %), Europe (12.9 %), and North America (8.8 %). The increasing stockpile of red mud has posed a huge challenge to safe disposal while restricting the development of the alumina industry. The comprehensive utilization of red mud still needs green, efficient, and massive consumption methods. This work gives a review of the engineered treatment of red mud, including the characteristics and threats, as well as the engineered application through construction materials, metal recovery, and soilization revegetation. For red mud with a high content of metals, resource recovery of valuable metals and rare earth elements is a preferred choice, meeting the circular economy concept. Recovery of valuable metals from red mud can be achieved by magnetic separation, hydrometallurgy, and bioleaching. Hydrometallurgy is promising for recovering valuable metals such as Fe, Al, V, Ti, and rare earth elements, and the recovery is up to 99 %. Construction materials such as cement, geopolymers, and ceramics is an efficient alternative for the massive consumption of red mud, and the high-performance concrete with the compressive strength (129.5 MPa) can be obtained. This strategy is limited by the low price of construction materials, the lowered quality by alkaline components, and potential threats of toxic elements in red mud. Soilization of red mud with ecological restoration is promising for the sustainable management of red mud dam. To accelerate the process of red mud soilization, amendments such as gypsum, organic matter, and microorganisms can be added to neutralize red mud (lowering pH from 10 to 12 to near 7), promote the formation of agglomerates, and provide nutrients, promote the conversion of red mud into soil-like substrate. The phytoremediation of red mud can be realized after effective regulation, finally realizing vegetation establishment of red mud. This work provides technological and practical guidance for the engineered disposal of red mud.

Budget Allocation Problem (BAP) for projects is considered one of the critical risks that necessitate the completion of projects in the shortest possible duration. This aspect is significant in extensive projects such as national endeavors directly impacting people's livelihoods. This research focuses on introducing Sustainable, Robust, Resilient, and Risk-averse Budget Allocation for Projects (S3RBAP). A hybrid robust stochastic optimization approach was employed, incorporating Weighted VaR (WVaR) and the minimum function as risk criteria to ensure the robustness of the objective function. This model is designed to minimize the weighted expected value, WVaR, and the minimum progress function, thereby promoting the 3R and sustainability framework to tackle budget fluctuations and enhance project viability. The case study revolves around the construction of national projects in Iran. Ultimately, the project's required budget was allocated within the budgetary constraints. Sensitivity analysis found that the integration of 3R and sustainability led to a 13.5 % reduction in the progress function compared to scenarios without these principles. Furthermore, increasing the conservatism coefficient to 20 % decreased the progress function to −0.58 %. Reducing the resiliency coefficient had an adverse effect by disrupting the budget allocation process. The computational time is increased gradually with the escalation of problem complexity, while the progress function decreases due to the increased number of projects. The findings demonstrate that using an exponential function promotes risk aversion, whereas a sine function encourages risk-seeking behaviour within this research context.

This study presents a life cycle assessment (LCA) of hospital waste management scenarios in Isfahan, Iran. Daily hospital waste generation totals 20 tons, with 44 % infectious and 56 % non-infectious waste. The non-infectious stream comprises 40 % food waste. Pyrolysis, chemical disinfection, composting, and material recovery were evaluated across ten environmental impact categories using TRACI 2014 methodology. Composting and material recovery reduce smog-forming emissions by 126.79 kg O₃ eq/ton and 129.02 kg O₃ eq/ton, respectively, and fossil fuel depletion by 255.04 MJ surplus/ton and 471.97 MJ surplus/ton compared to incineration. Chemical disinfection of infectious waste shows lower global warming potential (859.89 kg CO₂ eq/ton) than pyrolysis (1483.15 kg CO₂ eq/ton). The third scenario, prioritizing composting and material recovery, minimizes ecotoxicity with lowest emissions of cadmium (0.33 g/ton) and nickel (16.23 g/ton) to air, and arsenic (0.003 g/ton) and chromium (0.28 g/ton) to water. This study addresses a rarely assessed system in LCA literature, offering valuable insights for improving waste management in similar contexts worldwide. Recommendations include developing regulatory frameworks, investing in infrastructure, promoting collaboration, implementing training programs, and adopting circular economy principles. The research contributes to building life cycle thinking capability within the Iranian healthcare sector through stakeholder engagement, workshops, and public dissemination of findings.

Relatively recently, the significance of nanomaterials in several domains like materials science, chemistry, and biology has increased dramatically. Selenium is a vital trace element of enormous importance involved in electronics, sensors, catalysis, optics, and biological applications. The study's objective was to synthesize an enterocin conjugate with selenium nanoparticles to form a nanohybrid system that may increase the bioactivity of enterocin and overcome these hurdles. The nanohybrid system was characterized using the use of UV–vis, FTIR, XRD, EDX, TEM, Zeta potential and SEM. This system was used to health one risk assessment multi-drug resistance bacteria. The designed nanohybrid system showed high ability to growth inhibition of all these bacteria. As a result, the nanohybrid showed strong antibacterial activity against MDR bacteria using several accepted techniques. The biocidal effects of nanohybrid on tested bacteria was investigated using SEM. Upon examination, the results revealed damage, blebs, fusion, clumping, and uneven distribution in the cell wall of the tested bacteria, ultimately leading to cell death. The results showed that the system is good engineering design to kill bacteria. In addition, compared with bacteriocin alone, the nanohybrid showed promising antioxidant activity in vitro.

Winglet is a wingtip device that was developed to improve aircraft flight performance by reducing induced drag. The induced drag produced by the NXXX aircraft is considered too excessive because the simple wingtip currently available is still not optimal in reducing induced drag, so a new more optimal wingtip is needed. This research aims to analyze the influence of blended winglet parameters on the aerodynamic characteristics of the NXXX aircraft such as $C_L$ and $C_D$. Not only that, pitch moment coefficient ($C_M$) is also studied to determine how trim drag can increase with the consequent increase of aerodynamic efficiency ($C_L$/ $C_D$) which currently has not been specifically researched yet. Winglet parameters in this study include variations in taper ratio, winglet height, cant angle, trailing edge sweep, and blending radius that there is not enough analysis about it now. Computational Fluid Dynamics (CFD) simulation uses Ansys CFX with the Shear Stress Transport (SST) turbulence model is used to obtain wing aerodynamic data. This research concludes that the best winglet configuration is taper ratio of 0.2, blending radius of 15 %, winglet height of 30 %, cant angle of 15°, and trailing edge sweep of −0.6°. Apart from that, it was also found that all winglet configurations increased $C_L$, ${C_L}_{\max }$, and also lift slope ($a$). Almost all winglets also reduce the critical angle of attack, reduce $C_D$, and increase $C_M$. This simulation finds that addition of blended winglet can increase aerodynamic efficiency up to 17.51 % in cruise condition using the variation of winglet height.

This article emphasizes the findings of comparative thermal enhancement in Casson fluid using bases fluid as blood and Xue and Yamada-Ota hybrid nano-structures model towards a 3D swirling plate. Nanofluid flow is a widely investigated topic in engineering and industry, particularly in the cooling of electronic devices. Its proven ability to save energy makes it a viable option for improving cooling systems and sustainability initiatives. Thermal energy incorporates solar radiation, Soret and heat sources while transportation of species happens utilizing activation energy and Dufour impact. It was estimated that the system (partial differential equation) is converted into Odes employing finite element methodology. Such a complicated model is resolved efficient method named as finite element method. By enhancing impacts of chemical reaction and Dufour numbers, mass diffusion is enhanced but opposite behavior is noticed in mass diffusion with the change of Schmidt number. By increasing values of Lorentz force and velocity field inclines. Further, thickness (MBLs) increase with variation of Lorentz force and Casson parameter.

This paper presents the design of a filtering power amplifier (PA) with extra-high power-efficiency and wide bandwidth. To accomplish this, a novel approach is adopted by utilizing a wideband bandpass filter (BPF) as the output matching network (OMN) for the PA. The BPF compromises two paths, where each path consisting of two identical coupled lines that are interconnected to form a ring structure. The suggested configuration eliminates the need for a conventional OMN by integrating the input port of the filter with the drain node of the transistor, resulting in reduced size and losses and improved amplifier performance. The filter concept is illustrated using coupling matrix synthesis. A proof-of-concept filtering PA has been designed using a commercially available 10 W GaN HEMT. This amplifier was designed to operate in the frequency range of 3.0–5.0 GHz, yielding a fractional bandwidth of 50 %. According to achieved results, the drain efficiency and output power are 43.8–70.5 % and 40.2–41.8 dBm, respectively. As a result, the suggested filtering PA demonstrates significant performance in terms of filter bandwidth response and power amplification. Additionally, the proposed filtering PA has a broad operational bandwidth of 3.0–5.0 GHz, which covers the 5G New Radio (NR) n77 (3.3–4.2 GHz), n78 (3.3–3.8 GHz), and n79 (4.4–5.0 GHz) frequency bands.