Abstract
Gravitational energy storage systems are among the proper methods that can be used with renewable energy. However, these systems are highly affected by their design parameters. This paper ...presents a novel investigation of different design features of gravity energy storage systems. A theoretical model was developed using MATLAB SIMULINK to simulate the performance of the gravitational energy storage system while changing its design parameters. A parametric optimization study was also conducted using Taguchi and analysis of variance (ANOVA) techniques for optimizing the energy storage rate. Six parameters were studied; three are related to the piston design (diameter, height, and material density). The other parameters are the return pipe diameter, length, and charging/discharging time. Results revealed that the piston diameter and height are the two most significant parameters for the system performance compared to the other parameters, as they contributed by 35.11% and 30.28%, respectively. The optimization results indicated that the optimal piston diameter, height, and return pipe diameter were 0.25, 0.5, and 0.01 of the container height. The outcomes of this paper can significantly improve energy storage and power generation from renewable energy systems as it provides a reliable, economical, sustainable, and durable energy storage system.
•The effect of heptanol/diesel blends on diesel engine combustion is tested.•The BTE were increased when higher alcohol/diesel blends were used.•Higher alcohols have long ignition delay and the ...longest was for But10 and But20.•The highest combustion efficiency was achieved for Hept20.•The NOx and soot were reduced but CO and HC were increased for higher alcohol blends.
As there were limited efforts towards the substitution of diesel fuel with higher alcohols to operate diesel engine, the current work aims to evaluate diesel engine performance at wide operating conditions fuelled by blends of higher alcohols; including heptanol and octanol. To increase the trust of the received results, blends of lower alcohols (butanol) was studied where the attained results showed good agreement with those cited in the literature. Single-cylinder diesel engine setup equipped with the necessary sensors for measuring cylinder pressure, engine speed, output power, air flow rate, fuel flow rate and temperature at various locations in engine was used to realize the current objective. The study limits the blending ratios to be 10% and 20% v/v to keep the fuel system without any modifications. These blends showed stable and homogenous features for period of four months without phase separation. The steady state experiments were carried out at various engine loads (0%, 25%, 50% and 75% of the full load) and engine speeds (900 rpm and 1500 rpm). Results revealed that bsfc and BTE increased almost for all tested higher alcohol/diesel blends. The ignition delay increased with higher alcohols/diesel blends and the longest value was achieved by But10 and But20. The premixed combustion was enhanced for all tested higher alcohol/diesel blends. The highest cumulative net heat released was achieved for Hept20. The emissions of NOx and opacity were reduced while those of CO and HC emissions were increased for all tested higher alcohol/diesel blends compared to the corresponding values for D100.
The current study proposes a new strategy for using small hydroelectric turbines in downstream river branches with the least amount of construction and the lowest cost by comparing two different ...methods of installing the turbines, the first by installing the turbines at the river's bottom and the second by installing the turbines on floating boats. The methodology of this article is based on predicting the distribution of velocities through the watercourse using experimental data collected at various points in the river's depth, and then predicting the resulting electrical power for different sizes of turbines, as well as estimating the number of turbines for each row and the number of rows along the river. Therefore, Investigate the proposed systems. The proposed small hydropower system's economic viability and environmental impact are investigated in this article. According to the nature of the waterway, the best diameter of a turbine that can be used is 1.5 m based on water velocities and river depths. The proposed power plant generated 25.8 kW per single turbine row, with an estimated cost of produced power (0.035 USD/kWh) of approximately 20 turbines installed per row. Compared to other renewable energy sources, the proposed hydropower system is cost-effective and environmentally friendly, as generating electricity with the proposed small hydropower plant could reduce annual carbon dioxide emissions by 368 tones of CO2 per single turbine row.
Herein, novel, efficient and multifunctional heavy metals adsorbent is developed. Graphene sheets are facilely prepared using ultrasonication process with the aid of polyethyleneglycol. Then, ...spherical polypyrrole nanoparticles of an average size of 150 nm are polymerized on the surface of prepared graphene sheets using green method yielding nanocomposite. The developed graphene-polypyrrole nanocomposite is exploited for removal and recovery of Mn2+ from aqueous solution. The developed graphene-based nanocomposite achieved superior adsorption efficiency for removal of Mn2+ ions than polypyrrole nanoparticles of similar particle size. The new adsorbent achieved excellent removal efficiency of Mn2+ ions recording 89%. Additionally, the smart adsorbent shows antibacterial properties toward Staphylococcus aureus bacteria providing a clear bacterial inhibition zone of 10 mm. The influence of various adsorption parameters of adsorbent dose, contact time and initial metal ions concentrations on the adsorption Mn2+ are studied and optimized. The adsorption of Mn2+ ions on the nanocomposite is also evaluated using Langmuir and Freundlich models and the adsorption isotherms of Mn2+ are suitable and described well with the Langmuir model. Therefore, this study presents a new approach for the design and engineering of safe handling and processing of antibacterial adsorbent for efficient removal and recovery of heavy metal ions from wastewater.
•Efficient and multifunctional heavy metals adsorbent is developed.•Graphene sheets are facilely prepared using green approach.•Graphene - spherical nanoparticles with an average size 150 nm are developed.•The new adsorbent achieved excellent removal efficiency of 89% for Mn2+ ions.•The adsorbent achieved superior antibacterial properties toward Staphylococcus aureus bacteria.
In the last years, significant attentions have been paid in the state-of-the-literature to have precise current/voltage (I/V) polarization curves of polymer exchange membrane fuel cells (PEMFCs). ...This article presents a novel application of a very recent heuristic-based on technique, namely Salp Swarm Optimizer (SSO) to define the best values of unknown parameters of PEMFC model. The total of square deviations (TSD) between the actual and calculated results represents the objective function. The TSD is minimized by the proposed SSO-based methodology to insignificant values to ensure the concurrence and consistency between measured and estimated voltage points and subjects to set of constraints. Two test case studies of typical commercial stacked PEMFCs, namely NedStack PS6 and BCS 500-W PEM generator are performed to demonstrate the potential of the proposed procedure under various operating scenarios. Moreover, necessary comparisons to other optimizers under same data and conditions are in order. In addition to this, performance measures are made to evaluate the performance of the SSO. The simulations along with comparisons indicate that the proposed SSO-based on method is successfully used to characterize the PEMFC model precisely.
•An efficient SSO-based method is presented for PEMFC parameters' extraction.•The proposed method is demonstrated on two commercial PEMFCs.•The cropped best results are compared with other challenging optimisers.•Necessary performance measures are performed to appraise SSO results.•Various operating conditions are simulated.
•Viscosity of emulsified fuel depends on both water content and emulsion structure.•The emulsion structure affects engine mechanical and environmental performance.•Emulsified fuel with finer droplets ...has a better effect on engine performance.•Membrane emulsification is successfully used to regulate the emulsion structure.
In this work the effect of the structure of water-in-diesel fuel emulsion (WFE) on a three cylinder diesel engine performance has been investigated. Based on membrane emulsification, two different membranes of pore sizes of 0.2μm and 0.45μm has been individually used to change the emulsion structure while keeping the same WFE volumetric content (at 17% water volumetric content and 0.5% mixing emulsifier content). The Results showed that emulsions with large size of water droplets resulted in greater reduction in NOx emissions up to 25%. While, emulsions with finer droplets not only gave reductions in engine smoke and unburned hydrocarbons of values greater than 80% and 35% respectively, but also resulted in an increase of the engine effective efficiency up to 20%.
•The addition of trace metals in form of nanoparticles reduced the lag phase.•Nanoparticles reduced time to achieve the highest biogas and methane production.•Biogas and methane production were ...proportional to nanoparticles concentration.•Nanoparticles biostimulate the methanogenic bacteria and increase their activity.
Nanoparticles (NPs) were hypothesized to enhance the anaerobic process and to accelerate the slurry digestion, which increases the biogas and methane production. The effects of NPs on biogas and methane production were investigated using a specially designed batch anaerobic system. For this purpose, a series of 2L biodigesters were manufactured and implemented to study the effects of Cobalt (Co) and Nickel (Ni) nanoparticles with different concentrations on biogas and methane production. The best results of NPs additives were determined based on the statistical analysis (Least Significant Difference using M-Stat) of biogas and methane production, which were 1mg/L Co NPs and 2mg/L Ni NPs (p<0.05). These NPs additives delivered the highest biogas and methane yields in comparison with their other concentrations (0.5, 1, and 2mg/L), their salts (CoCl2, and NiCl2) and the control. Furthermore, the addition of 1mg/L Co NPs and 2mg/L Ni NPs significantly increased the biogas volume (p<0.05) by 1.64 and 1.74 times the biogas volume produced by the control, respectively. Moreover, the aforementioned additives significantly increased the methane volume (p<0.05) by 1.86 and 2.01 times the methane volume produced by the control, respectively. The highest specific biogas and methane production were attained with 2mg/L Ni NPs (p<0.05), and were 614.5mlBiogasg−1VS and 361.6mlCH4g−1VS, respectively compared with the control which yielded only 352.6mlBiogasg−1VS and 179.6mlCH4g−1VS.
Abstract
Artificial intelligence (AI) has given the electrocardiogram (ECG) and clinicians reading them super-human diagnostic abilities. Trained without hard-coded rules by finding often subclinical ...patterns in huge datasets, AI transforms the ECG, a ubiquitous, non-invasive cardiac test that is integrated into practice workflows, into a screening tool and predictor of cardiac and non-cardiac diseases, often in asymptomatic individuals. This review describes the mathematical background behind supervised AI algorithms, and discusses selected AI ECG cardiac screening algorithms including those for the detection of left ventricular dysfunction, episodic atrial fibrillation from a tracing recorded during normal sinus rhythm, and other structural and valvular diseases. The ability to learn from big data sets, without the need to understand the biological mechanism, has created opportunities for detecting non-cardiac diseases as COVID-19 and introduced challenges with regards to data privacy. Like all medical tests, the AI ECG must be carefully vetted and validated in real-world clinical environments. Finally, with mobile form factors that allow acquisition of medical-grade ECGs from smartphones and wearables, the use of AI may enable massive scalability to democratize healthcare.
Graphical Abstract
The application of artificial intelligence to the standard electrocardiogram enables it to diagnose conditions not previously identifiable by an electrocardiogram, or to do so with a greater performance than previously possible. This includes identification of the current rhythm, identification of episodic atrial fibrillation from an ECG acquired during sinus rhythm, the presence of ventricular dysfunction (low ejection fraction), the presence of valvular heart disease, channelopathies (even when electrocardiographically ‘concealed’), and the presence of hypertrophic cardiomyopathy.
•Al2O3 examined by XRD, FTIR, and TEM.•pmax, dp/dθmax and dQg/dθmax increased by 4.5%, 4% and 4%, respectively.•Brake specific fuel consumption decreased by 12%.•NOx, CO, UHC and Smoke opacity ...reduced by 70%, 80%, 60% and 35%, respectively.•Significant improvement in all engine performance was achieved at a concentration of 30 mg/l.
In the current work, an experimental investigation was conducted to recommend the optimal concentration of alumina nanoparticles (Al2O3) into Jojoba biodiesel-diesel (JB20D) fuel blend at which the best diesel engine performance and exhaust emissions were attained. The Al2O3 nanoparticles with concentrations varied from 10 to 50 mg/l by step of 10 mg/l were mixed into JB20D fuel blend with the help of ultrasonic stabilization. The results of the present study revealed that JB20D slightly reduced the engine performance and increased its emission characteristics at all engine tested operating conditions as compared to pure diesel oil. Utilizing of Al2O3 additives was found to improve all engine performance characteristics. However, the best emission characteristics were obtained at the dose level of 20 mg/l, where remarkable emissions reduction were observed; NOx by 70%, CO by 80%, UHC by 60%, and Smoke opacity by 35%. While the best of both mechanical performance and engine combustion characteristics were achieved at a concentration of 40 mg/l, where the reduction in the brake specific fuel consumption – bsfc was by 12% and increase in the cylinder peak pressure – pmax, the maximum rate of pressure rise – dp/dθmax, and maximum rate of gross heat release – dQg/dθmax were 4.5%, 4%, and 4%, respectively. According to the comparisons of engine performance and emissions, the recommended concentration of Al2O3 in JB20D blends was concluded to be 30 mg/l, which gave remarkable enhancement in all engine performance parameters.
In this paper, size-dependent bending, buckling and free vibration responses of functionally graded (FG) nanobeams are investigated using an integrated nonclassical continuum model. The integrated ...model accounts for the simultaneous effects of the microstructure local rotation and the surface energy in the framework of the nonlocal elasticity. The proposed nonlocal-couple stress-surface elasticity (NLCSSE) model is formulated by incorporating the Eringen nonlocal elasticity theory, modified couple stress theory and surface elasticity theory into the classical Euler–Bernoulli beam model. It is assumed that the material properties of the bulk and surface of the FG nanobeam change continuously through the thickness according to a power law. The size-dependent equations of motion and corresponding boundary conditions are derived utilizing the Hamilton's principle. The proposed model is validated by comparing the obtained results with available benchmark results. Numerical results are presented to reveal the effects of nonlocal parameter, material length scale parameter, surface energy, gradient index, Poisson ratio, thickness and length-to-thickness ratio on the deflection, critical buckling load and natural frequency of a FG simply supported nanobeam.
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