Search Results (58)

Urban air pollution poses significant risks to cultural heritage buildings, particularly in polluted megacities like Delhi, India. The Red Fort, a UNESCO World Heritage Site and a symbol of India’s rich history, is highly susceptible to degradation caused by air pollutants. Despite its great importance as an Indian and world heritage site, no studies have focused on characterizing its constituent materials or the degradation phenomena taking place. This study was developed in the framework of the MAECI (Italian Ministry of Foreign Affairs) and the Department of Science and Technology under the Ministry of Science and Technology, India, project: Indo—Italian Centre of Excellence for Restoration and Assessment of Environmental Impacts on Cultural Heritage Monuments. To understand their composition and degradation, Vindhyan sandstone and black crust samples were studied. Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) indicated that the red sandstone predominantly consisted of quartz and microcline, while the black crusts mainly comprised gypsum, bassanite, weddellite, quartz, and microcline. The analysis attributed the formation of gypsum to exogenous sources, such as construction activities and cement factory emissions. This pioneering study provides a basis for further research into the impacts of air pollution on Indian patrimony and promotes conservation strategies. Full article

For crop protection, electrostatic spraying technology significantly improves deposition uniformity and pesticide utilization through the “wraparound-adsorption” effect of charged droplets. However, existing electrostatic nozzles using hydraulic atomization suffer from low charge-to-mass ratios due to unclear principles for optimizing electrode parameters. To this end, this study designs and evaluates a novel air-assisted hydraulic-atomization hollow-cone electrostatic nozzle. First, the air-assisted hollow-cone nozzle was designed. High-speed imaging was then employed to obtain morphological parameters of the liquid film (length: 2.14 mm; width: 1.96 mm; and spray angle: 49.25°). Based on these parameters, an electric field simulation model of the electrostatic nozzle was established to analyze the influence of electrode parameters on the charging performance and identify the optimal parameter combination. Finally, feasibility and efficiency evaluation experiments were conducted on the designed electrostatic nozzle. The experimental results demonstrate that cross-sectional dimensions of the electrode exhibit a positive correlation with the surface charge density of the pesticide liquid film. In addition, optimal charging performance is obtained when the electrode plane coincides with the tangent plane of the liquid film leading edge. Based on these charging laws, the optimal electrode parameters were determined as follows: 2.0 × 2.0 mm cross-section with an electrode-to-nozzle tip distance of 3.8 mm. With these parameters, the nozzle achieved a droplet charge-to-mass ratio of 4.9 mC/kg at a charging voltage of 3.0 kV. These charged droplets achieved deposition coverages of 12.19%, 5.72%, and 5.91% on abaxial leaf surfaces in the upper, middle, and lower soybean canopies, respectively, which is a significant improvement in deposition uniformity. This study designed a novel air-assisted hollow-cone electrostatic nozzle, elucidated the optimization principles for annular induction electrodes, and achieved improved spraying performance. The findings contribute to enhanced pesticide application efficiency in crops, providing valuable theoretical guidance and technical references for electrostatic nozzle design and application. Full article

Food losses in developing countries occur predominantly during harvest and post-harvest stages due to inadequate infrastructure for processing agricultural produce into value-added products with an extended shelf life. Dehydration represents an effective method for preserving and enhancing the value of fruits and vegetables; however, conventional techniques entail significant energy expenditure, necessitating research into more sustainable and efficient processes. Solar dehydration emerges as a particularly suitable method due to its ability to utilize renewable energy resources, despite persistent technical constraints limiting its widespread implementation. This study presents the design, construction, and performance evaluation of a novel solar dryer incorporating both a drying chamber and an integrated photovoltaic system. The photovoltaic component powers a mechanical system that facilitates the removal of exhaust air, the introduction of fresh air, and homogeneous air circulation through the induction of turbulent flow patterns within the chamber. The results demonstrate that the optimal drying efficiency in solar dehydration systems is primarily contingent upon effective air homogenization and the systematic removal of moisture-laden air. The findings suggest that optimized solar dehydration technology can be considered as a technically viable and economically beneficial approach to mitigating post-harvest losses while simultaneously enhancing agricultural economic sustainability in developing regions. Full article

Spraying remains the primary method of pesticide application in plant protection, and spray drift is one of the important reasons that cause pesticide loss and environmental pollution. Air-induction spray is an anti-drift technology based on the Venturi effect. Unlike standard flat-fan sprays, the atomization mechanism of air-induction sprays has not yet been thoroughly studied. Therefore, a deep understanding of atomization and disintegration characteristics of air-induction spray liquid sheets is very important. This study utilized high-speed camera imaging technology to visualize the liquid sheet of air-induction sprays. Quantitative measurements were conducted on the disintegration length, spray angle, and bubble size of the liquid sheets. A comparative analysis was performed to examine the differences in liquid sheet structures between air-induction sprays and standard flat-fan sprays. The effects of different nozzle configurations and spray pressures on the liquid sheet of air-induction sprays were also discussed. The results indicate that bubbles are typical structures of the liquid sheets of the air-induction spray, and their disintegration can lead to perforations or interfacial disturbances in the liquid sheet. The study observed the coalescence of double or multiple bubbles within the liquid sheet, with atomized droplets potentially containing single or multiple bubbles. Compared to standard flat-fan sprays, air-induction sprays have smaller liquid sheet spray angles and disintegration lengths, by 23.48% and 16.32%, respectively. Bubble size decreases with increasing spray pressure but increases with larger nozzle orifice sizes. The spray angle of the liquid sheet significantly increases with higher spray pressures and larger nozzle orifice sizes. Meanwhile, the disintegration length of the liquid sheet shows a slight increase with rising spray pressures and larger nozzle orifice sizes. Full article

Spray drift is one of the major factors that causes pesticide loss and environmental pollution. Air-induction spray is an important anti-drift technology; however, the atomization characteristics of air-induction spray, particularly when the spray liquid is an oil-based emulsion, are not yet fully understood. In this paper, high-speed photography, PIV (particle image velocimetry) and image processing techniques are used to study the atomization characteristics of the air-induction spray under the oil-based emulsion condition. The structure of liquid sheet, the spatial distributions of the spray droplets size and the velocity are captured and measured. Additionally, the effects of spray pressure and nozzle configuration on atomization characteristics are discussed. The results indicate that, compared to water, air-induction spray under oil-based emulsion conditions exhibits a larger spray angle, a smaller droplet size, a narrower droplet size distribution and a higher droplet velocity. It is indicated that the oil-based emulsion reduces the size of bubbles within the liquid sheet, thereby decreasing the size of bubble-containing droplets. Furthermore, the oil-based emulsion alters the breakup mode of the liquid sheet, leading to an increase in droplet velocity and a narrower droplet size distribution. Both spray pressure and nozzle configuration have significant effect on the atomization characteristics. When the spray pressure changes from 0.1 MPa to 0.3 MPa and 0.5 MPa, the droplet size decreases by 10.56% and 15.67%, respectively, while the droplet velocity increases by 46.12% and 91.06%, respectively. When the nozzle changes from ID120-01 to ID120-03 and ID120-05, the droplet size increases by 20.64% and 33.99%, respectively, while the droplet velocity increases by 3.71% and 14.15%, respectively. Full article

The process of droplet formation during spraying is influenced by several factors, including the nozzle type and the use of adjuvants. This study aimed to investigate the effect of adding adjuvants to spray solutions using different nozzles, with a focus on droplet spectra, and to examine the impact of the contact angle and the surface tension on this process. The surface tension and contact angle were evaluated using a droplet shape analyzer. The experiment was conducted in a completely randomized design (CRD) using four treatment solutions: water alone and water mixed with three different types of adjuvants, including fatty acid esters (vegetable oil-based), polyether–polymethyl, and polydimethyl-siloxane. The droplet spectra (volume median diameter, relative amplitude, and droplets smaller than 100 µm) were assessed using a particle size analyzer. A CRD with a 4 × 2 factorial scheme was used to assess the effects of the four treatment solutions and two flat-fan nozzles (ULD 120-02 with air induction and LD 110-02 without air induction technology). The polyether–polymethyl considerably reduced the contact angle and surface tension (226% and 180%, respectively, in relation to water). However, it did not homogenize the droplet spectra or reduce the drift risk. The vegetable oil-based adjuvant increased the droplet size when the standard flat-fan nozzle was used. No significant correlation was found between the surface tension and contact angle regarding the droplet spectra parameters. The effect of adjuvants on the droplet spectra was found to be dependent on the nozzle type, which prevents generalizations about the implications of their use. Full article

The study aimed to assess the technological properties of six ethanolic phenolic-rich extracts derived from artichoke bracts, stems, and leaves using different extraction methods (maceration and ultrasonic-assisted extraction—UAE) for the formulation of oil-in-water emulsions in which pea protein concentrate served as an emulsifier. To this aim, the extracts were tested for their surface properties and their effect on the colloidal and antioxidant properties in emulsions. The extracts reduced the surface tension at the water/air interface in a dose-dependent manner, with the leaf extract obtained by UAE displaying the highest surface activity. In emulsions, the extracts increased oil droplet size and induced flocculation while being able to delay oxidation, as indicated by the induction period significantly higher compared to the control. In the last part of the work, encapsulation by spray-drying was explored on a selected leaf extract, and its release behavior in an enriched vegan mayonnaise was tested by in vitro digestion. The encapsulation influenced the release of phenolic compounds during simulated gastrointestinal digestion of the enriched vegan mayonnaise, demonstrating promising protective effects in the gastric environment and promoting a predominant release during the intestinal phase, potentially enhancing the absorption and bio-accessibility of the phenolic compounds. Full article

The conversion of air currents through wind turbine technology stands as one of the most significant and effective means of generating green electricity. Wind turbines featuring a horizontal axis exhibit the greatest installed capacity. The study establishes a mathematical model for large wind turbines, categorized by megawatt output, utilizing measured data for key parameters, including wind speed, power output from the generator, and rotational speed. The analysis of the system’s behavior on startup—the cut-in wind speed, is conducted by transitioning the electric generator into motor mode. A mathematical model has been established for the dual-powered motor configuration, wherein both the stator and rotor are connected to a common frequency network, facilitating a shift to synchronous motor functionality. The equation that describes the kinetic moment highlights the importance of attaining optimal velocity, while simultaneously accounting for variations in the load angle. These fluctuations are observable in both the power output and the electrical currents. The simulations that have been processed are derived from experimental data, specifically inputs obtained from a 1.5 MW wind turbine located in the Oravita region of southwestern Romania. The paper thus outlines essential elements concerning the functionality of high-power wind turbines that utilize wound rotor induction generators, aiming to guarantee optimal performance from the moment the wind speed reaches the cut-in threshold. Full article

This study developed a non-destructive testing (NDT) method using infrared thermography to inspect tubes with holes and slots made by electro-erosion and additive manufacturing. CO₂ was used as a tracer gas to verify the opening and evaluate the flow shape from the holes and slots. To improve the signal contrast, a controlled hot background was used as a reference, and infrared cameras monitored the thermal response to detect flow variations caused by different geometries. The tests included different diameters, pitches, and aspect ratios, comparing results between additive manufacturing and electro-erosion under various conditions. Moreover, a preliminary setup using compressed air and inductive heating was developed to assess hole openings by cooling the piece, aiming to eliminate CO₂ use. The comparison of results, the post-processing analysis of quantitative indices, and specific thermal features enabled a non-destructive evaluation of the holes by using different technologies, providing an assessment of the opening conditions, outlet, geometry, and flow shape. Full article

The integration of inductive charging technology in electric vehicles has aroused the interest of researchers in recent years. Specifically, one of the growing areas is wireless charging in Autonomous Underwater Vehicles (AUVs). In this environment, the effects of seawater in wireless power transmission should be carefully studied. Specifically, one of the effects that should be analysed is the appearance of parasitic capacitances ($C_e$) between the power coils due to the high conductivity of seawater. The parasitic capacitance, together with the power converters switching losses and the resistive and inductive losses, can lead to a drop in efficiency during the charging process. The main objective of this contribution is to find the optimal solution to avoid the effects of $C_e$ during the coils design, thus simplifying the process and making it equivalent to an air-based solution. To do so, different design criteria have been defined with a comparative analysis among different topologies proposed. Specifically, we have studied the variations of voltage, current, and efficiency caused by the $C_e$. Additionally, a comparison between Series-Series (SS) and LCC–Series (LCC–S) compensation systems has been considered, studying the system efficiency and maximum current values found on the circuit. The results of these studies have been verified through experimental validations, where the design and implementation of the elements that constitute the inductive charger have been performed. This validation has demonstrated the possibility of neglecting the effects of $C_e$ by optimising the coil’s design. Full article

The paper focuses on material characterization and technology properties of a new Ti-12Al-42Nb spherical powder alloy for additive manufacturing of personal medical implants. The electrode induction melting inert gas atomization (EIGA) method was used to produce the powder alloy. The powder sphericity coefficient (PSC) was 1.02. Image J software was used to calculate the spherical degree by processing images sets from scanning electron microscopy (SEM) and optical microscopy (OM). SEM of particles cross-sections indicated internal thermal-induced porosity (TIP) with a 2.3 μm pore diameter. Particle size distribution was in the range from 15.72 μm (d10) to 64.48 μm (d100) as measured by laser particle analyzer. It was indicated that flowability and powder bulk density were 196 sec and 2.79 g/cm³, respectively. XRD analysis confirmed the beta phase of the powder alloy with no additional phases. X-ray fluorescence spectrometry confirmed the alloyed composition. Reducing and oxidative melting methods of analysis showed a slight amount of impurities: oxygen (0.0087 wt.%), nitrogen (0.03 wt.%), hydrogen (0.0012 wt.%), sulfur (0.0016 wt.%), and carbon (0.022 wt.%). Simultaneous thermal analysis (STA) was performed to indicate weight growth and losses and thermal effects in argon, nitrogen, and air as well as the oxidation of Al₂O₃, TiO₂, and Nb₂O₅ on the surface layer of Ti-12Al-42Nb powder alloy particles. Different phase transformations of γAl₂O₃ $\to$ θAl₂O₃ $\to$ αAl₂O₃ and TiO₂ rutile $\to$ TiO₂ anatase phase transformation were detected by STA in the oxidative layer. Full article

This study aims to develop an efficient recovery solution for waste transformer insulating oil, addressing the challenge of incomplete separation of residual oil in existing recovery technologies. A multi-module integrated system is constructed, comprising a waste oil extraction module, a residual oil vaporization module, an exhaust gas treatment module, and an online monitoring module. By combining steps such as oil extraction, residual oil absorption, hot air circulation heating, and negative-pressure low-frequency induction heating, the complete recovery of waste oil is achieved. The recovery process incorporates oil–gas saturation monitoring and an oil–gas precipitation assessment algorithm based on neural networks to enable intelligent control, ensuring thorough recovery of residual oil from transformers. The proposed system and methods demonstrate excellent recovery efficiency and environmental protection effects during the pre-treatment of waste transformer oil. Experiments conducted on 50 discarded transformers showed an average recovery efficiency exceeding 99%, with 49 transformers exhibiting no damage to core components after the recovery process. From a theoretical perspective, this research introduces monitoring and control methods for transformer insulating oil recovery, providing significant support for the green processing and reutilization of discarded transformer insulating oil. From an application value perspective, the recovery process helps reduce environmental pollution and facilitates the disassembly of transformers. This enables better analysis of transformer operating characteristics, thereby enhancing the reliability and safety of power systems. Full article

The fundamental idea underlying the research presented in this paper was the desire to use less magnetically charged areas of the general construction of induction machines by increasing the active working surface by interposing a new internal stator armature. This results in a new air gap and foreshadows the advantage of increasing the torques developed by the motor considered, compared to the equivalent standard motor, at the same volume of iron. The following research-validation methods were followed: theoretical studies (analytical simulation and FEM), an experimental model (prototype), and testing on the experimental platform. We recall obtaining solid conclusions on the technological construction, functional and energy characteristics, as well as superior performances of over 50% regarding electromagnetic torques compared to the equivalent classic version. The prototype of this type of machine was surprising due to the ease with which the rotor can be rotated, highlighting the reduced inertia. In conclusion, concerning the problem addressed and the objectives pursued, the research had, in essence, an applied and experimental nature. The recent development of permanent-magnet synchronous motor constructions has led to the concept of creating such motors in the constructive configuration specified in the paper (two stators and two radial air gaps). Full article

This study proposes a three-stage, flexible and adaptable protocol for the establishment of field-scale agricultural management zones (AMZs) using remote sensing, ground truthing (apparent electrical conductivity and soil sampling), the IRRIGOPTIMAL^® system and machine learning. The methodology to develop this protocol was applied to olive and alfalfa plots in Heraklion (Crete, Greece) to monitor soil and plant responses for the period 2022–2024. However, the actual time for the implementation of this protocol varies between 3 and 6 months. The first step of this protocol involves the use of soil and vegetation reflectance mapping (moisture, photosynthetic activity) by satellites and unmanned aerial systems, together with geophysical electromagnetic induction mapping (apparent electrical conductivity) to verify soil variability, which is strongly linked to the delineation of management zones. In the second step, a machine learning-based prediction of the spatial distribution of soil electrical conductivity is made, considering the data obtained in the first step. Furthermore, in the second step, the IRRIGOPTIMAL^® system provides real-time monitoring of a variety of weather (such as air temperature, dew point, solar radiation, relative humidity, precipitation) and soil (temperature, moisture) parameters to support the optimal cultivation strategy for the plants. Once the data have been analysed, the soil variability of the plot and the presence or absence of cultivation zones are determined and the decision on the cultivation strategy is made based on targeted soil sampling and further soil analyses. This protocol could contribute significantly to the rational use of inputs (water, seeds, fertilizers and pesticides) and support variable rate technology in the agricultural sector of Crete. Full article

This paper presents the design process and resulting technical concept for an integrated hyperloop system, aimed at realizing efficient high-speed ground transportation. This study integrates various functions into a coherent and technically feasible solution, with key design decisions that optimize performance and cost-efficiency. An iterative design process with domain-specific experts, regular reviews, and a dataset with a single source of truth were employed to ensure continuous and collective progress. The proposed hyperloop system features a maximum speed of 600 $\frac{\mathrm{km}}{h}$ and a capacity of 21 passengers per pod (vehicle). It employs air docks for efficient boarding, electromagnetic suspension (EMS) combined with electrodynamic suspension (EDS) for high-speed lane switching, and short stator motor technology for propulsion. Cooling is managed through water evaporation at an operating pressure of 10 $\mathrm{m}$$\mathrm{bar}$, while a 300 $\mathrm{k}$$\mathrm{W}$ inductive power supply (IPS) provides onboard power. The design includes a safety system that avoids emergency exits along the track and utilizes separated safety-critical and high-bandwidth communication. With prefabricated concrete parts used for the tube, construction costs can be reduced and scalability improved. A dimensioned cross-sectional drawing, as well as a preliminary pod mass budget and station layout, are provided, highlighting critical technical systems and their interactions. Calculations of energy consumption per passenger kilometer, accounting for all functions, demonstrate a distinct advantage over existing modes of transportation, achieving greater efficiency even at high speeds and with smaller vehicle sizes. This work demonstrates the potential of a well-integrated hyperloop system to significantly enhance transportation efficiency and sustainability, positioning it as a promising extension to existing modes of travel. The findings offer a solid framework for future hyperloop development, encouraging further research, standardization efforts, and public dissemination for continued advancements. Full article