Search Results (1,196)

This article presents a methodology for real-time forecasting of a fire-extinguishing agent jet trajectory from a robotic fire monitor under wind influence, which can significantly displace the impact area position and complicate targeting. The proposed methodology is designed for controlling firefighting robots in conditions where visual monitoring of the impact area is impeded by factors such as: obscuration of the fire-extinguishing agent flow by smoke, low visibility of its fragmented particles against the background environment, and long-range jet discharge. Trajectory forecasting is implemented using a neural network model. The training and verification of this model are performed with datasets constructed from the results of numerical simulations of fire-extinguishing agent motion under wind influence, based on Computational Fluid Dynamics (CFD) methods. Experimentally obtained data are used for the validation of the trained neural network model and the selected CFD models. The paper describes the methodology for conducting full-scale tests of fire monitors; a photogrammetric algorithm for generating validation datasets from the test results; an algorithm for calculating target characteristics, which describe the jet trajectory and are consistent with experimental data, used for forming training and verification datasets based on simulation; and a procedure for selecting Computational Fluid Dynamics models and their parameters to ensure the required accuracy. The article also presents the results of an experimental evaluation of the developed methodology’s effectiveness for real-time prediction of the water jet trajectory from a fire monitor under various control and disturbance parameters. Full article

Objective: This study aims to analyze relationships between body composition, biochemical parameters, and cardiac function in young adults to identify mechanisms of cardiac dysfunction in obesity. Methods: This is a cross-sectional study of 60 young adults (mean age 20.4 years) divided into healthy (n = 29) and overweight/obese (n = 31) groups. Body composition was assessed using bioelectrical impedance analysis. We calculated the SMM-to-Fat ratio (skeletal muscle mass %/body fat %) as a continuous composite metric. Cardiac function was evaluated using 3D speckle-tracking echocardiography, with a 3D global circumferential strain pre-specified as the primary endpoint. Results: The obese group showed unfavorable body composition with lower SMM% (38.0 ± 10.8 vs. 47.1 ± 5.6%), higher body fat% (28.3 ± 12.6 vs. 16.0 ± 8.3%), and lower SMM-to-Fat ratio (2.1 ± 2.3 vs. 4.8 ± 5.1; all p < 0.001). C-peptide was 75% higher (p < 0.001), indicating compensatory hyperinsulinemia. The primary endpoint showed impairment in the obese group (−19.8 ± 4.7 vs. −22.2 ± 2.9%; p = 0.023, d = 0.61), while longitudinal strain was preserved, indicating selective mid-wall dysfunction. The SMM-to-Fat ratio demonstrated a stronger association with circumferential strain (r = −0.467, p = 0.008) than SMM% alone (r = −0.414, p = 0.021) and remained an independent predictor in multivariable analysis (β = −0.88, p = 0.019), whereas SMM% did not achieve significance (p = 0.159). Comprehensive analysis revealed correlation reversal across all body composition parameters between groups, with minerals% and total body water% emerging as additional independent predictors. Conclusions: Young obese adults exhibit selective mid-wall cardiac dysfunction. The SMM-to-Fat ratio, representing muscle–adiposity balance, is superior to SMM% alone for predicting cardiac dysfunction. Our findings suggest that the relative balance, rather than absolute muscle mass, determines cardiac health in obesity, with implications for body composition assessment and intervention strategies. Full article

The present study assesses the effectiveness of the indole-type alkaloid Yohimbine (YHB) as a green corrosion inhibitor for OLC52 carbon steel and Al in 0.25/0.25 mol L⁻¹ acetic acid/potassium acetate solutions relevant for de-icing applications. Electrochemical techniques, including cyclic and linear sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopy have been combined with the evaluation of adsorption isotherms and molecular modeling calculations. YHB significantly decreases the corrosion rate for both metals, attaining inhibitory efficiencies of up to 95% for OLC52 and 91% for Al at 298 K, while maintaining high protection efficiency even at higher temperatures. The Langmuir adsorption model and the values of $∆G_{ads}^o$ between −31 and −41 kJ mol⁻¹ indicate a spontaneous adsorption process defined by a mixed physicochemical mechanism, resulting in the formation of a compact protective film. Quantum molecular descriptors support the ability of YHB molecules to interact with metal surfaces via donor–acceptor interactions and electrostatic interactions. The findings demonstrate the potential of YHB as an environmentally friendly inhibitor for the protection of ferrous and non-ferrous alloys in mildly acidic acetic/acetate media used in de-icing solutions. Full article

Background/Objectives: Bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA) are the gold standard to measure fat mass, but they are unavailable in regular consultations. Relative Fat Mass (RFM) and Pediatric Relative Fat Mass (pRFM) equations are calculated using DXA images in adults and children, but they have not been correlated with BIA. Methods: A longitudinal prospective study was conducted with 531 children from a public school followed over one year; sex, age, weight, height, waist circumference and fat mass percentage were recorded. We calculated body mass index Z-score (Z-BMI), body mass index percentile (Pc BMI), waist-to-height ratio (WHtR), and RFM-pRFM to diagnose Overweight (Ow)/Obesity (Ob). We used descriptive statistics, Pearson’s correlation, sensitivity and specificity, 95% CI, and ROC curves; SPSS version 22 was used. Results: Adiposity was found in 34.5%, 33.2%, 21.5% and 43.5% of children using Z-BMI, Pc BMI, WHtR, and BIA, respectively; excluding children younger than 8 years old, the frequency of adiposity was 51.5% by RFM-pRFM. The highest correlation was between RFM-pRFM and BIA (0.84, p < 0.000). Of the total measurements of each visit considered as normal weight using Z-BMI, 21.5% had adiposity using BIA, and the proportion of girls underdiagnosed was twice that of boys. Conclusions: RFM-pRFM had the highest correlation with BIA but Z-BMI, Pc BMI, and WHtR are also helpful. It is important to consider that 21.5% of children with apparent normal weight present adiposity. Full article

Current upper-limb rehabilitation robots primarily focus on training tasks involving free movements or static interactions with rigid objects. These paradigms lack simulation of complex object manipulation tasks encountered in daily life, thereby limiting the training of patients’ high-level sensorimotor integration capabilities. To address this gap, this study proposes an innovative robotic rehabilitation training system designed for functional occupational therapy. Specifically, the task of transporting a water cup was abstracted into a cup–ball system integrated with a robotic arm. The ball was modeled as a point mass, and kinematic and dynamic analyses of the system were conducted. A visual tracking method was employed to monitor the ball’s motion and calculate its slosh angle. Owing to the impaired fine motor control in stroke patients, a sloshing suppression control strategy integrating exponential filtering, feedforward force compensation, and impedance control was proposed to prevent the ball from spilling. Experiments validated the effectiveness of the proposed method. The results indicated that with full compensation, the oscillation rate of the ball was significantly reduced, and the smoothness of the hand force was markedly improved. This study presents an effective method for addressing dynamic uncertainty in rehabilitation robot training, thus significantly improving the functional relevance of the training. Full article

With the increasing demand for sustainable building materials, it has become essential to identify sustainable alternatives to conventional sound absorbers, particularly in the context of waste reduction and the circular economy. The aim of this study was to compile and describe a structured dataset of sound absorption coefficients for laboratory-produced panels made from recycled textile materials. Five types of panels were developed using cotton, polyester, wool, linen, and a mixed composition of textiles. A biopolymer binder was applied to ensure structural stability of the materials. Following careful sorting, shredding, and homogenization of the textile waste, test specimens were prepared and examined under controlled laboratory conditions. The sound absorption coefficients were measured using an AFD 1000 impedance tube in accordance with the ISO 10534-2 standard, across a frequency range from 6.25 to 6393.75 Hz. For each material, three repeated measurements were performed, and mean values were calculated to ensure accuracy and reliability. The resulting dataset contains structured values of sound absorption coefficients, which can be applied in building acoustics modeling, comparative studies with conventional insulation materials, and the development of new sustainable products. In addition, the data can be used in educational contexts and machine learning applications to predict the acoustic properties of recycled textile composites. Full article

As typical dynamic loads, electric vehicles (EVs) introduce significant uncertainty into distribution network operations due to the randomness of their travel behavior and charging demand. To achieve precise spatiotemporal forecasting of charging loads, this paper constructs a multi-dimensional transportation network model that accounts for dynamic road impedance factors and introduces a unit-distance energy consumption calculation method based on road impedance. By integrating the division of urban multifunctional zones and differentiated state-of-charge (SOC) threshold distributions across various EV types, a mapping model between travel chains and charging behaviors is established. Subsequently, large-scale travel and charging events are generated using an origin–destination (OD) probability matrix and Monte Carlo sampling to derive the spatiotemporal distribution of regional EV charging loads. Simulation results for a representative city in southwest China show that the predicted charging loads exhibit a dual-peak pattern, with significant differences across regions and vehicle types, and align well with observed load trends, validating the effectiveness and engineering applicability of the proposed method. Full article

Objectives: Graves’ disease (GD) is the most common cause of hyperthyroidism and is associated with marked changes in body weight and body composition. Although weight loss is frequently reported, the extent and clinical relevance of body composition alterations, as well as their relationship with thyroid function, remain unclear. This study aimed to evaluate body composition and eating habits in patients with newly diagnosed hyperthyroid GD according to pre-morbid weight variation, and to compare these findings with those of matched euthyroid controls. Methods: Forty-four consecutive GD patients were enrolled and stratified based on the presence or absence of pre-morbid weight loss. Anthropometric measurements, thyroid function tests, thyroid volume, dietary habits (PREDIMED score, macronutrient intake and total daily caloric intake) and body composition assessed by bioelectrical impedance analysis (BIA) were collected. Standardized phase angle (SPA) and body cell mass index (BCMI) were calculated as nutritional indices. Body composition parameters and dietary adherence were compared with those of 44 age-, sex- and BMI-matched euthyroid controls. Results: Most GD patients (70.3%) reported weight loss before diagnosis; however, the magnitude of weight change did not correlate with the biochemical severity of thyrotoxicosis. Patients without weight loss showed higher fat mass percentage and higher caloric intake than those who lost weight. SPA was significantly associated with FT3, FT4 and TRAb levels, independently of age, sex, BMI and fat mass. Compared with controls, GD patients exhibited lower phase angle and SPA, higher extracellular water percentage and reduced BCMI, whereas fat mass and adherence to the Mediterranean diet were similar. Conclusions: Hyperthyroid GD patients display increased extracellular water and reduced body cell mass. SPA is inversely associated with GD severity and represents a valuable clinical tool for assessing nutritional status in thyrotoxic patients. Pre-morbid weight changes are not proportional to disease severity and may instead reflect increased caloric intake. Full article

The compact and wideband patch antennas applied to WiFi 7 multiple-input multiple-output (MIMO) antenna systems are presented. The MIMO antenna structure consists of four multi-branch radiating patches fed by coupled microstrip lines, which occupies a size of $32\times 32\times 1 {\mathrm{m}\mathrm{m}}^3$. By exploiting multiple resonant modes, an impedance bandwidth of 37% (5.07–7.37 GHz) achieves a reflection coefficient of less than −10 dB and fully encompasses both WiFi 7 high-frequency ranges. To alleviate mutual coupling, two decoupling structures, named complementary split-ring resonators (CSRRs), are employed between the MIMO elements to interact with the undesirable surface current; furthermore, the proposed orthogonal placement of four elements further minimizes radiation coupling. Consequently, the proposed array achieves measured isolations greater than 14.5 dB and 11 dB at 5 GHz and 6 GHz bands, respectively. The prototype of the proposed MIMO antenna has been manufactured. It has also been measured and the results show similarity with the simulations. The measured radiation pattern and the diversity performance, including the envelope correlation coefficient (ECC), diversity gain (DG), and multiplexing efficiency, are calculated, and they verify the outstanding diversity characteristics of the proposed MIMO antenna. This makes it a promising solution for emerging WiFi 7 wideband applications. Full article

To develop molecularly imprinted polymer (MIP)-based biosensors effectively, it is necessary to evaluate the potential adsorption of materials onto the electrode surface. Therefore, we investigated the adsorption of geraniol and pyrrole and compared them. In addition to determining adsorption constants, particular focus was placed on adsorption mechanisms, as they directly influence monolayer or multilayer formation, template removal efficiency, and the selectivity of the final imprinted structure. To achieve this, we employed various electrochemical methods, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and quartz crystal microbalance (QCM) measurements. Measurements were repeated to ensure reliability. The findings were used to calculate adsorption constants using the Langmuir equation. Geraniol and pyrrole showed adsorption constants of 21.5 L/mol and 31.7 L/mol, respectively, indicating strong molecular interactions. These results indicate strong interactions between the two molecules, suggesting that geraniol influences electrode polymerization. This led to the importance of proper surface preparation, evaluation of analyte–monomer interactions, and the opportunity to reuse materials. Full article

Two series of glasses with compositions (90 − x)TeO₂-xV₂O₅-10Bi₂O₃ and (80 − x)TeO₂-xV₂O₅-20Bi₂O₃, where x = 20, 30, 40 mol %, were synthesized. Glasses were obtained by the melt-quenching technique. The molar volume (33.48–48.37 cm³/mol) and oxygen packing density (71.69–77.64 mol/cm³) were calculated based on experimental density measurements. Both parameters increase with the increase in V₂O₅ and the decrease in TeO₂ content. Infrared spectra were recorded in the range of 2000–400 cm⁻¹ and Raman spectra in the 90–1280 cm⁻¹ range. The C1s, O1s, Te3d, V2p and Bi4f photoelectron lines were recorded. The dielectric characteristics of the glasses were measured by impedance spectroscopy at room temperature in the frequency range from 100 Hz to 1 MHz. The glasses in the studied system demonstrate a strong dependence on the composition, with the occasional addition of high contents of TeO₂ and V₂O₅ leading to a significant change in the dielectric properties of the samples. Full article

The seawater corrosion behavior of a plain carbon steel covered with hydrothermally carbonized coating was studied. Hydrothermal carbonization of sugar (sucrose) dissolved in water with a concentration of 10 wt.% at 200 °C for 4 h was carried out to produce a carbonized coating on the steel. The corrosion resistance of the steel with and without the carbonized coating was evaluated by polarization tests in seawater. The Tafel slopes were calculated using polarization data. The corrosion current and the potential of corrosion were determined to examine the effect of the carbonized coating on the corrosion behavior of the steel. In addition, AC impedance measurements on the steel without and with the hydrothermal carbonization coating were performed in a three-electrode cell with a Ag/AgCl reference electrode, platinum counter electrode, and seawater electrolyte. It was found that hydrothermal carbonization of sugar generated a continuous carbon-rich layer on the surface of the steel. This carbon layer is highly corrosion-resistant as shown by the decrease in the corrosion current. It is concluded that the hydrothermally carbonized coating has the nature of passivation films, and it can slow down the corrosion rate of the plain carbon steel in seawater. The impedance of the steel without hydrothermal carbonization coating is very low. With hydrothermal carbonization coating, an increase in the resistance and the capacitive response of the coating/seawater interface was observed. Full article

In order to realize the wide frequency applicability of the electromagnetic current transformer in a ‘double high’ power system, the equivalent circuit model of the electromagnetic current transformer under wide frequency is established. The complex permeability method is used to obtain the excitation impedance value on the basis of the existing core parameters. Secondly, according to the equivalent circuit of the current transformer in the broadband domain, the error transfer function of the electromagnetic current transformer is derived. Through simulation calculation, the ratio difference and angle difference in the electromagnetic current transformer at 50 Hz–3000 Hz are obtained. The correctness of the theoretical analysis and simulation model is verified by comparing it with the existing model and measurement. The simulation and test results show that the electromagnetic current transformer has good linearity when the frequency is in the frequency range of 50 to 650 Hz. When the frequency exceeds this frequency, the ratio difference and angle difference in the current transformer will not reach the accuracy standard, which indicates that it is difficult to accurately measure the high frequency current. Aiming at the correlation of frequency characteristics, this paper proposes a method of optimizing parameters, which provides a certain reference for the error compensation and structural design of electromagnetic current transformers. Full article

Modern power distribution systems are increasingly stressed as they operate closer to their voltage stability limits, driven by growing electricity demand, complex load behaviors, and the evolving structure of power networks. Radial distribution systems, in particular, are highly susceptible to voltage instability under critical loading conditions, where even minor load increases can trigger voltage collapse. Such events threaten the continuity and quality of power supply and can cause damage to infrastructure and sensitive equipment. While large-scale cascading failures are typically associated with transmission systems, localized cascading effects such as sequential voltage drops, feeder outages, and protective device operations can still occur in distribution networks, especially under high loading. Therefore, reliable and timely voltage stability assessment is essential to maintain system reliability and prevent disruptions. This study presents a comprehensive comparative analysis of four voltage stability indices designed for radial distribution networks. The performance of these indices is evaluated on the IEEE 33-bus and 69-bus test systems under various critical loading conditions and multiple static load models, including Constant Power Load (CPL), Constant Current Load (CIL), Constant Impedance Load (CZL), Composite Load (COML), and Exponential Load (EXL). The analysis investigates each index’s effectiveness in identifying voltage collapse points, estimating critical load levels, and calculating load margins, while also evaluating their robustness across diverse operating scenarios. The findings offer practical insights and serve as a valuable benchmark for selecting suitable voltage stability indicators to support monitoring and planning in modern distribution networks. Full article

Titanium (Ti) alloy sheets are important mechanical and structural components. However, thickness deviations may occur during the production of Ti-alloy sheets, significantly compromising product quality and structural safety. Eddy current testing (ECT) is a common method for measuring the thickness deviation of metal sheets. Nevertheless, conventional ECT methods often rely on complex calibration procedures or iterative inversion algorithms, thereby limiting their applicability. It was found that when low-frequency ECT excitation is used, such that the eddy current penetration depth exceeds three times the maximum target thickness of the Ti-alloy sheet, the tangent of the ECT coil impedance phase exhibits a linear relationship with the thickness. Based on this observation, by analyzing the low-frequency ECT response of Ti-alloys and separating the real and imaginary parts of the impedance under approximate conditions, a phase feature model was developed. The model effectively describes the linear dependence of the phase tangent on the thickness of the Ti-alloy sheet, offering a succinct characterization. The measurement method based on this model thereby allows for direct thickness calculation from the measured coil impedance without requiring master-curve calibration or iterative computation. Experiments were conducted using a custom-designed ECT coil and impedance analyzer to measure different Ti-alloy specimens. The results indicate that the measurement error was less than 3.5%. This research provides a theoretical foundation as well as a straightforward engineering solution for online, high-speed thickness measurement of Ti-alloy sheets. Full article