Search Results (378)

The growing need to improve the management of end-of-life vehicle (ELV) waste and mitigate its environmental impact is a global concern. One promising approach to enhancing the recyclability of these vehicles is leveraging synergies between the automotive and construction industries as part of a circular economy strategy. In this context, ELV waste emerges as a valuable source of secondary raw materials, enabling the development of sustainable innovations that capitalize on its physical and mechanical properties. This paper aims to develop and evaluate construction industry composites incorporating waste from ELV carpets, with a focus on maintaining or enhancing performance compared to conventional materials. To achieve this, an experimental program was designed to assess cementitious composites, specifically subfloor mortars, incorporating automotive carpet waste (ACW). The results demonstrate that, beyond the physical and mechanical properties of the developed composites, the dynamic stiffness significantly improved across all tested waste incorporation levels. This finding highlights the potential of these composites as an alternative material for impact noise insulation in flooring systems. From an academic perspective, this research advances knowledge on the application of ACW in cement-based composites for construction. In terms of managerial contributions, two key market opportunities emerge: (1) the commercial exploitation of composites produced with ELV carpet waste and (2) the development of a network of environmental service providers to ensure a stable waste supply chain for innovative and sustainable products. Both strategies contribute to reducing landfill disposal and mitigating the environmental impact of ELV waste, reinforcing the principles of the circular economy. Full article

With rising global temperatures and increasing sustainability demands, the need for advanced pavement solutions has never been greater. This study breaks new ground by integrating phase change materials (PCMs), including paraffin-based wax (Rubitherm RT55), hydrated salt (Climator Salt S10), and fatty acid (lauric acid), as binder modifiers within warm mix asphalt (WMA) mixtures. Moving beyond the traditional focus on binder-only modifications, this research utilizes recycled cigarette filters (CFs) as a dual-purpose fiber additive, directly reinforcing the asphalt mixture while simultaneously transforming a major urban waste stream into valuable infrastructure. The performance of the developed WMA mixture has been evaluated in terms of stiffness behavior using an Indirect Tensile Strength Modulus (ITSM) test, permanent deformation using a static creep strain test, and rutting resistance using the Hamburg wheel-track test. Laboratory tests demonstrated that the incorporation of PCMs and recycled CFs into WMA mixtures led to remarkable improvements in stiffness, deformation resistance, and rutting performance. Modified mixes consistently outperformed the control, achieving up to 15% higher stiffness after 7 days of curing, 36% lower creep strain after 4000 s, and 64% reduction in rut depth at 20,000 passes. Cost–benefit analysis and service life prediction show that, despite costing USD 0.71 more per square meter with 5 cm thickness, the modified WMA mixture delivers much greater durability and rutting resistance, extending service life to 19–29 years compared to 10–15 years for the control. This highlights the value of these modifications for durable, sustainable pavements. Full article

Background/Objectives: Affecting close to one-third of the global population, metabolic dysfunction-associated steatotic liver disease (MASLD) is a highly prevalent chronic liver disorder linked to metabolic risk factors such as obesity and insulin resistance. Liver fibrosis is a key determinant of prognosis, and its progression increases the risk of liver-related and overall mortality. This exploratory research evaluated the potential impact of a 3-month intervention involving dietary counseling and liraglutide therapy on liver fibrosis and related metabolic markers in patients with MASLD and obesity without diabetes. Methods: In this prospective, single-arm exploratory intervention, 28 adult patients with MASLD and obesity received structured dietary counseling and daily subcutaneous liraglutide for 12 weeks. Liver fibrosis was assessed using non-invasive indices (FIB-4, APRI, BARD, ELF) and transient elastography performed with the FibroScan^® device (Echosens, Paris, France). Results: After 3 months, a significant reduction in liver stiffness (−7.14%, p < 0.05) and ELF score (from 6.71 to 6.63; −1.2%, p < 0.05) was observed. APRI (p = 0.06) and FIB-4 (p = 0.09) showed trends toward improvement, while the BARD score and AST/ALT ratio remained unchanged. Conclusions: Short-term liraglutide therapy combined with lifestyle modification may improve early-stage liver fibrosis in patients with MASLD and obesity, as indicated by reductions in liver stiffness and ELF score. These preliminary findings highlight the potential of advanced non-invasive fibrosis markers in monitoring treatment response. However, as an exploratory study, results should be interpreted with caution, and larger, long-term trials are needed to confirm these observations and evaluate efficacy in patients with more advanced fibrosis stages. Full article

The global prevalence of hypertension continues to rise, affecting an estimated one billion worldwide. Regular exercise is well recognized as a non-pharmacological approach for individuals with hypertension due to its blood pressure (BP)-lowering effect, largely attributed to repeated exposure to post-exercise hypotension (PEH). Recent evidence also indicates that aromatherapy can contribute to BP reduction, indicating that combining aromatherapy with exercise may enhance the overall BP-lowering effects. Therefore, this pilot study aimed to investigate the effects of aromatherapy on PEH during the recovery phase following exercise. Fourteen healthy young males (22.7 ± 0.7 yrs) participated in this randomized crossover-designed study. All participants completed two exercise sessions per week, each lasting 30 min, at a target heart rate (HR) of 60–65%. The individuals inhaled either aroma oil or water vapor at 5, 35, 65, and 95 min after exercise. The HR, BP, blood lactate level, and arterial stiffness index were measured before and after the exercise. Our findings revealed the following. (1) PEH occurred in both groups. (2) In the aroma group, PEH was augmented compared with the control group, with the maximum reduction in BP being greater in the aroma group. (3) The reduction in arterial stiffness was greater and longer in the aroma group than in the control group. (4) The changes in the lactate levels after exercise did not differ between the groups. Our findings indicate that aromatherapy can amplify PEH, suggesting that its use after exercise may help maximize the positive effects of exercise on BP reduction. Full article

This study introduces an analytical framework that integrates the state-space method with generalized thermoelasticity theory to obtain exact solutions for the static and dynamic behaviors of laminated plates featuring imperfect interfaces and resting on a Winkler foundation. The model comprehensively accounts for the foundation-structure interaction, interfacial imperfection, and the coupling between the thermal and mechanical fields. A parametric analysis explores the impact of the dimensionless foundation coefficient, interface flexibility coefficient, and thermal conductivity on the static and dynamic behaviors of the laminated plates. The results indicate that a lower foundation stiffness results in higher sensitivity of structural deformation with respect to the foundation parameter. Furthermore, an increase in interfacial flexibility significantly reduces the global stiffness and induces discontinuities in the distribution of stress and temperature. Additionally, thermal conductivity governs the continuity of interfacial heat flux, while thermo-mechanical coupling amplifies the variations in specific field variables. The findings offer valuable insights into the design and reliability evaluation of composite structures operating in thermally coupled environments. Full article

Background and Objectives: Type 2 diabetes mellitus (T2DM) is associated with subclinical cardiovascular changes, such as increased arterial stiffness and myocardial dysfunction. Vitamin D deficiency has been recognized as a potential contributing factor to vascular disease; however, its impact on early cardiac changes associated with T2DM remains poorly understood. Our aim was to evaluate the association between serum levels of 25-hydroxyvitamin D3 [25(OH)D3], arterial stiffness, and left ventricular global longitudinal strain (LV GLS) in patients with T2DM who do not have a clinically evident cardiovascular disease. Material and methods: This cross-sectional study evaluated the carotid intima–media thickness (IMT), aortic pulse wave velocity (PWVao), LV GLS, and serum 25(OH)D3 levels in patients diagnosed with T2DM (n = 65) compared to healthy control subjects (n = 55). Independent predictors of arterial stiffness were identified by a multivariate logistic regression analysis. Results: Patients with T2DM showed a significant increase in IMT and PWVao, a reduction in LV GLS, and low levels of 25(OH)D3 compared to subjects in the control group (all p < 0.05). Both vitamin D deficiency and T2DM were found to be independently associated with an increased arterial stiffness, with odds ratios of 2.4 and 4.8, respectively. A significant inverse relationship was identified between 25(OH)D3 levels and markers of arterial stiffness, as well as LV GLS, suggesting a possible association between the vitamin D status and the early onset of cardiovascular dysfunction. Conclusions: Patients with T2DM show early signs of heart and blood vessel problems, even with an ejection fraction that remains within normal limits. There is a significant correlation between vitamin D deficiency and increased arterial stiffness, along with impaired LV GLS, indicating its possible involvement in cardiovascular complications associated with diabetes. These findings support the utility of integrating vascular, myocardial, and vitamin D assessments in early cardiovascular risk stratification for T2DM patients. Full article

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver condition globally, strongly linked to obesity, insulin resistance, and type 2 diabetes (T2D). Tirzepatide (TZP), a dual GIP/GLP-1 receptor agonist, improves glycemic control and reduces body weight and the liver fat content in patients with obesity and T2D. However, its effect on liver-specific outcomes such as steatosis and fibrosis remains incompletely characterized. Low-energy ketogenic therapy (LEKT), a nutritional strategy characterized by carbohydrate restriction and nutritional ketosis, may enhance hepatic β-oxidation and reduce hepatic lipogenesis. To date, however, the combination of TZP and LEKT has not been studied in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). This study aimed to compare the hepatic and metabolic effects of TZP combined with either LEKT or a conventional low-calorie diet (LCD) over a 12-week period. Methods: Sixty adult patients with MASLD undergoing TZP therapy were prospectively assigned to either an LEKT or a conventional LCD, with 30 participants per group. As primary endpoints, the controlled attenuation parameter (CAP, an index of hepatic steatosis) and liver stiffness measurement (LSM, an index of liver fibrosis) were assessed at the baseline and after 12 weeks using FibroScan^®. Secondary outcomes included changes in body mass index (BMI), glycated hemoglobin (HbA1c), and liver enzymes. Adherence to both diet and pharmacological treatment, as well as tolerability, were systematically monitored throughout the intervention period. Results: Both groups showed significant reductions in body weight (TZP + LEKT, p = 0.0289; TZP + LCD, p = 0.0278), with no significant intergroup difference (p = 0.665). CAP and LSM improved significantly in both groups, but reductions were greater in the TZP + LEKT group (CAP −12.5%, p < 0.001; LSM −22.7%, p < 0.001) versus LCD (CAP −6.7%, p = 0.014; LSM −9.2%, p = 0.022). Between-group differences were statistically significant for both CAP (p = 0.01) and LSM (p = 0.03). Conclusions: Based on these preliminary findings, we support the hypothesis that the combination of TZP and LEKT may be superior to TZP with an LCD in reducing hepatic steatosis and stiffness in individuals with obesity. Full article

This paper presents some of the most significant findings in the design of a hydraulic servomechanism for flight controls, which were primarily achieved by the first author during his activity in an aviation institute. These results are grouped into four main topics. The first one outlines a classical theory, from the 1950s–1970s, of the analysis of nonlinear automatic systems and namely the issue of absolute stability. The uninformed public may be misled by the adjective “absolute”. This is not a “maximalist” solution of stability but rather highlights in the system of equations a nonlinear function that describes, for the case of hydraulic servomechanisms, the flow-control dependence in the distributor spool. This function is odd, and it is therefore located in quadrants 1 and 3. The decision regarding stability is made within the so-called Lurie problem and is materialized by a matrix inequality, called the Lefschetz condition, which must be satisfied by the parameters of the electrohydraulic servomechanism and also by the components of the control feedback vector. Another approach starts from a classical theorem of V. M. Popov, extended in a stochastic framework by T. Morozan and I. Ursu, which ends with the description of the local and global spool valve flow-control characteristics that ensure stability in the large with respect to bounded perturbations for the mechano-hydraulic servomechanism. We add that a conjecture regarding the more pronounced flexibility of mathematical models in relation to mathematical instruments (theories) was used. Furthermore, the second topic concerns, the importance of the impedance characteristic of the mechano-hydraulic servomechanism in preventing flutter of the flight controls is emphasized. Impedance, also called dynamic stiffness, is defined as the ratio, in a dynamic regime, between the output exerted force (at the actuator rod of the servomechanism) and the displacement induced by this force under the assumption of a blocked input. It is demonstrated in the paper that there are two forms of the impedance function: one that favors the appearance of flutter and another that allows for flutter damping. It is interesting to note that these theoretical considerations were established in the institute’s reports some time before their introduction in the Aviation Regulation AvP.970. However, it was precisely the absence of the impedance criterion in the regulation at the appropriate time that ultimately led, by chance or not, to a disaster: the crash of a prototype due to tailplane flutter. A third topic shows how an important problem in the theory of automatic systems of the 1970s–1980s, namely the robust synthesis of the servomechanism, is formulated, applied and solved in the case of an electrohydraulic servomechanism. In general, the solution of a robust servomechanism problem consists of two distinct components: a servo-compensator, in fact an internal model of the exogenous dynamics, and a stabilizing compensator. These components are adapted in the case of an electrohydraulic servomechanism. In addition to the classical case mentioned above, a synthesis problem of an anti-windup (anti-saturation) compensator is formulated and solved. The fourth topic, and the last one presented in detail, is the synthesis of a fuzzy supervised neurocontrol (FSNC) for the position tracking of an electrohydraulic servomechanism, with experimental validation, in the laboratory, of this control law. The neurocontrol module is designed using a single-layered perceptron architecture. Neurocontrol is in principle optimal, but it is not free from saturation. To this end, in order to counteract saturation, a Mamdani-type fuzzy logic was developed, which takes control when neurocontrol has saturated. It returns to neurocontrol when it returns to normal, respectively, when saturation is eliminated. What distinguishes this FSNC law is its simplicity and efficiency and especially the fact that against quite a few opponents in the field, it still works very well on quite complicated physical systems. Finally, a brief section reviews some recent works by the authors, in which current approaches to hydraulic servomechanisms are presented: the backstepping control synthesis technique, input delay treated with Lyapunov–Krasovskii functionals, and critical stability treated with Lyapunov–Malkin theory. Full article

During operation, dynamic cables endure coupled thermo-mechanical loads (mechanical: tension/bending; thermal: power transmission) that degrade stiffness, amplifying extreme responses and impairing configuration optimization. To address this, this study pioneers a multi-objective optimization framework integrating stiffness characteristics from mechanical/thermo-mechanical analyses, with objectives to minimize dynamic extreme tension and curvature under constraints of global configuration variables and safety thresholds. The framework employs a Radial Basis Function (RBF) surrogate model coupled with NSGA-II algorithm, yielding validated Pareto solutions (≤6.15% max error vs. simulations). Results demonstrate universal reduction in extreme responses across optimized configurations, with the thermo-mechanically optimized solution achieving 20.24% fatigue life enhancement. This work establishes the first methodology quantifying thermo-mechanical coupling effects on offshore cable safety and fatigue performance. This configuration design scheme exhibits better safety during actual service conditions. Full article

The dynamic control of vibrations in skyscrapers is a critical consideration in sustainable building design, particularly in response to environmental excitations such as wind impact or seismic activity. Effective vibration neutralisation plays a crucial role in providing the safety of high-rise buildings. This research introduces an innovative concept for an active vibration damper that operates based on fluid dynamic transport to adaptively alter a skyscraper’s natural frequency, thereby counteracting resonant vibrations. A distinctive feature of this system is an adjustable-length cable mechanism, allowing for the dynamic modification of the pendulum’s effective length in real time. The structure, based on cable length adjustment, enables the PTMD to precisely tune its natural frequency to variable excitation conditions, thereby improving damping during transient or resonance phenomena of the building’s dynamic behaviour. A comprehensive mathematical model based on Lagrangian mechanics outlines the governing equations for this system, capturing the interactions between pendulum motion, fluid flow, and the damping forces necessary to maintain stability. Simulation analyses examine the role of initial excitation frequency and variable damping coefficients, revealing critical insights into optimal damper performance under varied structural conditions. The findings indicate that the proposed pendulum damper effectively mitigates resonance risks, paving the way for sustainable skyscraper design through enhanced structural adaptability and resilience. This adaptive PTMD, featuring an adjustable-length cable, provides a solution for creating safe and energy-efficient skyscraper designs, aligning with sustainable architectural practices and advancing future trends in vibration management technology. The study presented in this article supports the development of modern skyscraper design, with a focus on dynamic vibration control for sustainability and structural safety. It combines advanced numerical modelling, data-driven control algorithms, and experimental validation. From a sustainability perspective, the proposed PTMD system reduces the need for oversized structural components by providing adaptive, efficient damping, thereby lowering material consumption and embedded carbon. Through dynamically retuning structural stiffness and mass, the proposed PTMD enhances resilience and energy efficiency in skyscrapers, lowers lifetime energy use associated with passive damping devices, and enhances occupant comfort. This aligns with global sustainability objectives and new-generation building standards. Full article

This study presents a computational approach to optimize the stiffness distribution of large deformable elastic braces (LDEBs), which possess a high elastic deformation capacity and are designed to enhance the seismic performance of building structures. An optimization problem was formulated to minimize the seismic response of two-story buildings modeled as multi-degree-of-freedom systems, in which both the building frame and the LDEBs were represented by spring elements. Seismic responses under earthquake excitations were evaluated through time-history analyses. Particle swarm optimization (PSO) was employed to determine the optimal stiffness ratios of LDEBs that minimize the maximum story drift. Extensive round-robin analyses were conducted to verify the validity of the PSO results, generating response surfaces that mapped the maximum story drift against the LDEBs’ stiffness under three different earthquake records. The analysis revealed that the optimal solutions obtained from the PSO coincided with the global minimum identified in the round-robin response surfaces. These results confirm the effectiveness of the proposed optimization framework and demonstrate the potential of LDEBs for enhancing seismic resilience in structural designs. Full article

Background/Objectives: Scapular adaptations have been associated with shoulder pain. However, conflicting findings have been reported after scapular-focused interventions. The present study aims to evaluate scapula-related outcomes before and after a scapular therapeutic exercise program. Methods: Eighteen adult volunteers with chronic shoulder pain participated in an 8-week scapular therapeutic exercise program that was personalized according to their pain condition and the presence of scapular dyskinesis. This program included preparation and warm-up, scapular neuromotor control, and strengthening and stretching exercises. Both self-reported (shoulder pain and function, psychosocial factors, and self-impression of change) and performance-based outcomes (scapular muscular stiffness and activity level, tridimensional motion, rhythm, and movement quality, measured while participants drank a bottle of water) were used for analysis. Results: After the intervention, participants presented reduced shoulder pain (p < 0.0001) and pain catastrophizing (p = 0.004) and increased shoulder function (p < 0.0001). Additionally, the participants presented changes in scapular winging (p < 0.0001 to p = 0.043), increased scapular downward rotation (p < 0.0001) and depression (p = 0.038), and decreased global movement smoothness (p = 0.003). These were associated with changes in serratus anterior activity (p = 0.016 to p = 0.035), decreased middle (p < 0.0001 to p = 0.002) and lower trapezius (p < 0.0001) and levator scapulae (p = 0.048) activity levels, and decreased middle trapezius muscle stiffness (p = 0.014). Patients’ self-perception of change was rated favorably. Conclusions: After a scapular therapeutic exercise program, changes were observed in both self-reported and performance-based outcomes. These results need to be confirmed by a randomized controlled trial. Full article

Evaluating noise, vibration, and harshness (NVH) performance is crucial in vehicle development. However, NVH evaluation is often subjective and challenging to achieve through numerical simulation, and typically prototypes are required. Dynamic driving simulators are emerging as a viable solution for assessing NVH performance in the early development phase before physical prototypes are available. However, most current simulators can reproduce vibrations only in a single direction or within a limited frequency range. This paper presents a comprehensive design optimization approach to enhance the dynamic response of a full-spectrum driving simulator, addressing these limitations. Specifically, in complex driving simulators, vibration crosstalk is a critical and common issue, which usually leads to an inaccurate dynamic response of the system, compromising the realism of the driving experience. Vibration crosstalk manifests as undesired vibration components in directions other than the main excitation direction due to structural coupling. To limit the system crosstalk, a flexible multibody dynamics model of the driving simulator has been developed, validated, and employed for a global sensitivity analysis. From this analysis, it turns out that the bushings located below the seat play a crucial role in the crosstalk characteristics of the system and can be effectively optimized to obtain the desired performances. Bushings’ stiffness and locations have been used as design variables in a multiobjective optimization with the aims of increasing the direct transmissibility of the actuators’ excitation and, at the same time, reducing the crosstalk contributions. A surrogate model approach is employed for reducing the computational cost of the process. The results show substantial crosstalk reduction, up to 57%. The proposed method can be effectively applied to improve the dynamic response of driving simulators allowing for their extensive use in the assessment of vehicles’ NVH performances. Full article

Polynitrogen compounds have broad applications in the field of high-energy materials, making the exploration of two-dimensional polynitride materials with both novel properties and practical utility a highly attractive research challenge. Through global structure search methods and first-principles theoretical calculations at the Perdew–Burke–Ernzerhof (PBE) level of density functional theory (DFT), the globally minimum-energy configuration of a novel planar BeN₃ monolayer (tetr-2D-BeN₃) is predicted. This material exhibits a planar quasi-isotropic structure containing pentagonal, hexagonal, and dodecagonal rings, as well as “S”-shaped N6 polymeric units, exhibiting a high energy density of 3.34 kJ·g⁻¹, excellent lattice dynamic stability and thermal stability, an indirect bandgap of 2.66 eV (HSE06), high carrier mobility, and ultraviolet light absorption capacity. In terms of mechanical properties, it shows a low in-plane Young’s stiffness of 52.3–52.9 N·m⁻¹ and a high in-plane Poisson’s ratio of 0.55–0.56, indicating superior flexibility. Furthermore, its porous structure endows it with remarkable selectivity for hydrogen (H₂) and argon (Ar) gas separation, achieving a maximum selectivity of up to 10²³ (He/Ar). Therefore, the tetr-2D-BeN₃ monolayer represents a multifunctional two-dimensional polynitrogen-based energetic material with potential applications in energetic materials, flexible semiconductor devices, ductile materials, ultraviolet photodetectors, and other fields, thereby expanding the design possibilities for polynitride materials. Full article

This study addresses the challenge of accurately modeling the dynamic behavior of industrial robots for precision manufacturing applications. Using a comprehensive experimental approach with modal impulse hammer testing and triaxial acceleration measurements, 360 frequency response functions were recorded along orthogonal measurement paths for a KUKA KR10 robot. Two dynamic models with different parameter dimensions (12-parameter and 24-parameter) were developed in Matlab/Simscape, and their parameters were identified using genetic algorithm optimization. The KUKA KR10 features Harmonic Drives at each joint, whose high transmission ratio and zero backlash characteristics significantly influence rotational dynamics and allow for meaningful static structural measurements. Objective functions based on the Frequency Response Assurance Criterion (FRAC) and Root Mean Square Error (RMSE) metrics were employed, utilizing a frequency-dependent weighting function. The performance of the models was evaluated across different robot configurations and frequency ranges. The 24-parameter model demonstrated significantly superior performance, achieving 70% overall average Global FRAC in the limited frequency range (≤200 Hz) compared to 41% for the 12-parameter model when optimized using a representative subset of 9 measurement points. Both models showed substantially better performance in the limited frequency range than in the full spectrum. This research provides a validated methodology for dynamic characterization of industrial robots and demonstrates that higher-dimensional models, incorporating transverse joint compliance, can accurately represent robot dynamics up to approximately 200 Hz. Future work will investigate nonlinear effects such as torsional stiffness hysteresis, particularly relevant for Harmonic Drive systems. Full article