Search Results (4,247)

Optimizing structural resistance against blast loads critically depends on the effects of different explosive shapes, equivalents, and distances on the damage characteristics of reinforced concrete beams. This study bridges the knowledge gap in understanding how these factors influence damage mechanisms through close-range air blast experiments and LS-DYNA numerical simulations. Key damage characteristics, such as craters, overpressure, impulse, time-history displacement, and residual mid-span displacement of reinforced concrete beams, were thoroughly analyzed. Results show that cuboid-shaped explosives cause the greatest damage, with the most severe effects observed at shorter distances and higher charge weights, including an increase in mid-span displacement of up to 16.3 cm. The study highlights the pivotal role of explosive geometry, charge weight, and standoff distance in shock wave propagation and structural failure and proposes an optimized damage criterion to enhance predictive capabilities for reinforced concrete beams under blast loads. Full article

In recent years, the macro–micro structure (servo platform for macro motion and galvanometer for micro motion) composed of a galvanometer and servo platform has been gradually applied to laser processing in order to address the increasing demand for high-speed, high-precision, and large-format precision machining. The research in this field has evolved from step-and-scan methods to linkage processing methods. Nevertheless, the existing linkage processing methods cannot make full use of the field-of-view (FOV) of the galvanometer. In terms of motion distribution, the existing methods are not suitable for continuous micro segments and generate the problem that the distribution parameter can only be obtained through experience or multiple experiments. In this research, a new laser linkage processing method for global trajectory smoothing of densely discretized paths is proposed. The proposed method can generate a smooth trajectory of the servo platform with bounded acceleration by the finite impulse response (FIR) filter under the global blending error constrained by the galvanometer FOV. Moreover, the trajectory of the galvanometer is generated by vector subtraction, and the motion distribution of macro–micro structure is accurately realized. Experimental verification is carried out on an experimental platform composed of a three-axis servo platform, a galvanometer, and a laser. Simulation experiment results indicate that the processing efficiency of the proposed method is improved by 79% compared with the servo platform processing only and 55% compared with the previous linkage processing method. Furthermore, the method can be successfully utilized on experimental platforms with good tracking performance. In summary, the proposed method adeptly balances efficiency and quality, rendering it particularly suitable for laser precision machining applications. Full article

Background: Small airway dysfunction (SAD) is associated with impaired asthma control, but small airway physiology is not routinely assessed in clinical practice. Previously, we demonstrated impulse oscillometry (IOS)-defined small airway dysfunction (SAD) in dual responders (DRs) upon bronchoprovocation with various allergens. Aim: To compare lung physiology using spirometry and IOS following bronchoprovocation with methacholine (M) and inhaled house dust mite (HDM) extract in corticosteroid-naïve asthmatic subjects. Methods: Non-smoking, clinically stable HDM-allergic asthmatic subjects (18–55 years, FEV₁ > 70% of pred.) underwent an M and inhaled HDM challenge on two separate days. Airway response was measured by IOS and spirometry, until a drop in FEV₁ ≥ 20% (PC₂₀) from post-diluent baseline (M), and up to 8 h post-allergen (HDM). Early (EAR) and late asthmatic response (LAR) to HDM were defined as ≥20% and ≥15% fall in FEV₁ from post-diluent baseline during 0–3 h and 3–8 h post-challenge, respectively. IOS parameters (Rrs5, Rrs20, Rrs5-20, Xrs5, AX, Fres) were compared between mono-responders (MRs: EAR only) and dual responders (EAR + LAR). Correlations between maximal % change from baseline after the two airway challenges were calculated for both FEV₁ and IOS parameters. Results: A total of 47 subjects were included (11 MRs; 36 DRs). FEV₁ % predicted did not differ between MR and DR at baseline, but DR had lower median PC₂₀M (0.84 (range 0.07–7.51) vs. MR (2.15 (0.53–11.29)); p = 0.036). During the LAR, DRs had higher IOS values than MRs. For IOS parameters (but not for FEV₁), the maximal % change from baseline following M and HDM challenge were correlated. PC₂₀M was inversely correlated with the % change in FEV₁ and the % change in Xrs5 during the LAR (r= −0.443; p = 0.0018 and r= −0.389; p = 0.0075, respectively). Conclusions: During HDM-induced LAR, changes in small airway physiology can be non-invasively detected with IOS and are associated with increased airway hyperresponsiveness and changes in small airway physiology during methacholine challenge. DRs have a small airways phenotype, which reflects a more advanced airway disease. Full article

This study investigates speech intelligibility and its influencing factors within pier-style airport lounges and assesses the applicability of the Speech Transmission Index (STI) in these large, elongated spaces. Field impulse response measurements were conducted in two pier-style departure lounges with volumes of 98,099 m³ and 60,414 m³, respectively, complemented by simulated binaural room impulse responses for subjective speech intelligibility testing in Mandarin. The research explores the correlations between various acoustic parameters—Early Decay Time (EDT), Reverberation Time (T₃₀), and Definition(D₅₀)—and speech intelligibility scores under different Signal-to-Noise Ratios (SNRs). Findings indicate a significant impact of SNR on speech intelligibility, with a coefficient of determination (R²) of 0.849, suggesting substantial variability explained by SNR. As SNR increases to 10 dB(A), speech intelligibility scores improve significantly; however, further enhancements in clarity diminish beyond this threshold. Additionally, the study reveals a significant relationship between room acoustic parameters, particularly EDT and D50, and speech intelligibility scores, with EDT having a negative impact and D50 a positive impact on speech clarity. The results confirm the suitability of STI in evaluating speech intelligibility in these specific architectural contexts. This study recommends maintaining an SNR of 10 dB(A) and a minimum STI of 0.45 for public address broadcasts in pier-style departure lounges to ensure that announcements are clearly audible to passengers. Full article

This study delves into the synchronization issues of the impulsive fractional-order, mainly the Caputo derivative of the order between 0 and 1, bidirectional associative memory (BAM) neural networks incorporating the diffusion term at a fixed time (FXT) and a predefined time (PDT). Initially, this study presents certain characteristics of fractional-order calculus and several lemmas pertaining to the stability of general impulsive nonlinear systems, specifically focusing on FXT and PDT stability. Subsequently, we utilize a novel controller and Lyapunov functions to establish new sufficient criteria for achieving FXT and PDT synchronizations. Finally, a numerical simulation is presented to ascertain the theoretical dependency. Full article

Background: Information is limited regarding the role of impulse oscillometry (IOS) for the detection of preserved ratio impaired spirometry (PRISm). Therefore, we aimed to study the diagnostic ability of IOS in differentiating between PRISm and healthy subjects. Methods: This retrospective data collection was done at the Lung Health Center, Faculty of Medicine, Chiang Mai University, Thailand between July 2019 and April 2022. The potential diagnostic possibilities of difference in resistance at 5 Hz (R5) and resistance at 20 Hz (R20) (R5-R20) for PRISm detection were analyzed. Results: The prevalence of PRISm was higher when using the fixed ratio (FR) criteria (FEV₁/FVC ≥0.7 with FEV₁ < 80% of predicted value) compared to the lower limit of normal (LLN) criteria (FEV₁/FVC ≥ LLN and FEV₁ < LLN) (10.0% vs. 4.2%). The %prediction for R5-R20 provided an acceptable area under the curve (AUC) for PRISm, defined by the LLN and the FR criteria (AuROC = 0.75 (95%CI; 0.64, 0.85) and 0.72 (95%CI; 0.63, 0.81), respectively). The cut-off value of %predicted R5-R20 ≥120% resulted in the highest sensitivity and specificity for detecting PRISm. Conclusions: The %predicted of R5-R20 ≥ 120% showed an acceptable performance for PRISm detection and PRISm may be detected by IOS. Full article

This study explores the fatigue properties of EN AW-6082-T6 aluminum alloy in the gigacycle range (10⁶–10⁹ cycles), using ultrasonic resonance fatigue testing at 20 kHz in a push–pull mode with a symmetric load cycle (R = −1). A custom-built ultrasonic fatigue machine, developed at TU-Varna, comprising a generator, ultrasonic train (including a high-power transducer, booster, custom-made sonotrode, and specimen), monitoring, data logging systems, and an air-cooling capability, was used for the experiments conducted. A Bezier curve sonotrode, with an amplification ratio of 1:6, was designed and produced for the test. Hourglass-shaped specimens were designed on the base of the dynamic Young’s modulus E = 71.3 GPa, determined through the impulse resonance method (ASTM E1876-01), and validated with FEM analysis for resonance length and stress amplitude. The fatigue testing revealed a fatigue strength reduction of approximately 60 MPa between 10⁶ and 10⁹ cycles. The percentile of failure curves based on a Cactillo–Canteli model fits well with the experimental data and gives a fatigue limit at 10⁹ cycles σl = 104 MPa and “endurance strength” σw = 84 MPa. Surface crack initiation was consistently observed with predominately cleavage transgranular fractures in the fatigue zone. The present research highlights the utility of ultrasonic testing for examining fatigue behavior in the gigacycle regime. Full article

We conducted a comprehensive study of the non-equilibrium dynamics of Cooper pair breaking, quasiparticle (QP) generation, and relaxation in niobium (Nb) cut from superconducting radio-frequency (SRF) cavities, as well as various Nb resonator films from transmon qubits. Using ultrafast pump–probe spectroscopy, we were able to isolate the superconducting coherence and pair-breaking responses. Our results reveal both similarities and notable differences in the temperature- and magnetic-field-dependent dynamics of the SRF cavity and thin-film resonator samples. Moreover, femtosecond-resolved QP generation and relaxation under an applied magnetic field reveals a clear correlation between non-equilibrium QPs and the quality factor of resonators fabricated by using different deposition methods, such as DC sputtering and high-power impulse magnetron sputtering. These findings highlight the pivotal influence of fabrication techniques on the coherence and performance of Nb-based quantum devices, which are vital for applications in superconducting qubits and high-energy superconducting radio-frequency applications. Full article

Shear wave elastography (SWE) is an advanced ultrasound technique that assesses tissue stiffness by measuring shear wave speed (SWS) produced after an acoustic impulse. It includes bidimensional (2D-SWE) and focal point (pSWE) methods, allowing qualitative and quantitative analysis of tissue stiffness. This study aimed to describe the elastographic features of testicular abnormalities in dogs, supported by histological findings. Eighteen dogs with testicular abnormalities underwent B-mode ultrasound, power and color Doppler ultrasound, 2D-SWE, and pSWE before orchiectomy. Five cryptorchid testes were excluded and thirty-one testes (12 normal, 7 with leydigomas, 6 with seminomas, 1 with a round cell tumor, and 5 with orchitis) were examined. Normal testes, lesions, and adjacent healthy tissues (no evident ultrasound changes, NEUC) were sampled. Testicular abnormalities presented SWS values of 1.05–4.89 m/s (2D-SWE) and 1.35–5.31 m/s (pSWE). Significant differences were observed among normal testes, NEUC areas, and those with orchitis, leydigomas, and seminomas by both 2D-SWE and pSWE. Normal testes were significantly softer than ones with leydigomas, seminomas, and orchitis, and NEUC areas also had different SWS values compared to those with tumors and orchitis (p < 0.05). However, SWE techniques lacked specificity in differentiating between orchitis and tumors. Diagnostic accuracy of SWE techniques for testicular lesions remains challenging and requires further investigation to fully address its clinical potential. Full article

Introduction: In 2019, an updated version of the Diagnostic Interview for ADHD in Adults (DIVA-5) was developed based on DSM-5 criteria, currently validated in Korean and Farsi. The aim of this study is to validate the DIVA-5 Italian version. Methods: 132 subjects in the Adult ADHD Screening Center of AUSL-Modena, who agreed to participate in this study, were selected. Socio-demographic and clinical variables were collected. DIVA-5, Barkley Adult ADHD Rating Scale (BAARS), and Adult ADHD Self Rating Scale (ASRS-v1.1) were administered. We assessed the internal consistency of the DIVA-5 Italian version and its concurrent validity with ASRS-v1.1 and BAARS-IV. An exploratory factor analysis (EFA) was conducted to evaluate the construct validity, and a multiple linear regression to evaluate the predictive validity. Results: Our analysis indicated good internal consistence of the DIVA-5 Italian version (Cronbach’s alpha and Kuder coefficients ranged between 0.61 and 0.78). The EFA showed five factors representing specific variance. The correlation between the corresponding ADHD dimensions of DIVA-5 and BAARS was found to be statistically significant (Spearman’s coefficient ranged between 0.61 and 0.47, p = 0.000), while the correlation between the DIVA-5 dimensions and ASRS-v1.1 was statistically significant for all the dimensions except child hyperactivity/impulsivity. The multiple linear regression showed a positive association of the DIVA-5 score with the “job” variable and a negative association with “drug therapy”. DIVA-5 showed greater sensitivity for inattention in adulthood and greater specificity for hyperactivity/impulsivity in childhood. Conclusions: Our results confirm that the DIVA-5 Italian version represents a valid and reliable tool to diagnose adult ADHD. Full article

Executive functions (EFs) are essential cognitive processes involved in concentration, planning, decision-making, and impulse control during adolescence. Executive Dysfunction (ED) can lead to significant academic and socio-emotional difficulties, particularly with impairments in emotion regulation (ER). This study aims to assess a virtual reality (VR) cognitive training intervention on EFs, ER, and internalizing symptoms in adolescents at risk for ED. Thirty-eight adolescents aged 12–14 years, identified as being at moderate to high risk for ED, were randomly assigned to two groups. The experimental group (n = 22) received gamified VR cognitive training, while the control group (n = 16) received VR nature-based relaxation training. Both interventions lasted five weeks, twice a week for 30 min each. Pre- and post-assessments included ER skills, internalizing symptoms, and cognitive performance measures. Two-way mixed ANOVAs showed significant group × time interactions (p < 0.05) in measures of depression and internalizing symptoms. The experimental group showed significant reductions in these symptoms compared with the control group. Significant main effects of time (p < 0.05) were also found on some measures. Both groups experienced reduced anxiety, improved emotional control and cognitive functioning, and VR cognitive training was particularly effective in reducing internalizing symptoms, while both interventions showed promising results in improving some ER skills and cognitive performance. The findings demonstrate the preliminary effects of VR-based cognitive training in improving the psychological and cognitive well-being of adolescents at risk for ED and suggest that integrating VR technologies into educational settings can effectively address the cognitive and emotional challenges faced by these students. Full article

This paper introduces a convolution model with non-singular rational kernels in which coefficients are considered complex. An interlacing property of the poles and zeros in these rational kernels permits the accurate approximation of the power law function $t^{-\nu }$ in a predefined time range, where $\nu$ can be complex or real. This class of model can be used to model fractional (dynamical) behaviours in order to avoid fractional calculus-based models which are now associated with several limitations. This is an extension of a previous study by the author. In the real case, this allows a better approximation, close to the limits of the approximation interval, compared to the author’s previous work. In the complex case, this extends the scope of application of the convolution models proposed by the author. Full article

This study evaluates different machine learning algorithms in detecting and identifying drones using radar data from a 60 GHz millimeter-wave sensor. These signals were collected from a bionic bird and two drones, namely DJI Mavic and DJI Phantom 3 Pro, which were represented in complex form to preserve amplitude and phase information. The first benchmarks used four algorithms, namely long short-term memory (LSTM), gated recurrent unit (GRU), one-dimensional convolutional neural network (Conv1D), and Transformer, and they were benchmarked for robustness under noisy conditions, including artificial noise types like white noise, Pareto noise, impulsive noise, and multipath interference. As expected, Transformer outperformed other algorithms in terms of accuracy, even on noisy data; however, in certain noise contexts, particularly Pareto noise, it showed weaknesses. For this purpose, we propose Multimodal Transformer, which incorporates more statistical features—skewness and kurtosis—in addition to amplitude and phase data. This resulted in a improvement in detection accuracy, even under difficult noise conditions. Our results demonstrate the importance of noise in processing radar signals and the benefits afforded by a multimodal presentation of data in detecting unmanned aerial vehicle and birds. This study sets up a benchmark for state-of-the-art machine learning methodologies for radar-based detection systems, providing valuable insight into methods of increasing the robustness of algorithms to environmental noise. Full article

Truss systems are essential structural elements widely utilized for their lightweight design, high load-bearing capacity, and structural efficiency. This study introduces a novel energy-based method for analyzing time-dependent deformations in viscoelastic truss systems, applicable to both statically determinate and indeterminate configurations. The primary objective is to develop a total potential energy (TPE) functional that explicitly incorporates viscoelastic effects, system parameters, material properties, and loading conditions. Unlike conventional methods that treat viscous terms as non-conservative and lacking a clear energy representation, the proposed approach facilitates a direct and efficient energy-based formulation of the governing equations. The methodology employs the Laplace transform to simplify the problem and an inverse Laplace transform to recover solutions in the time domain. This systematic approach ensures accurate results while reducing computational effort, making it both time-efficient and straightforward to implement. A key advantage of the proposed method is its adaptability to various viscoelastic material models, such as the Kelvin–Voigt and Standard Linear Solid (SLS) models, and its applicability to diverse loading conditions, including step and impulsive loads. To validate the method, numerical analyses are conducted on truss systems subjected to different time-dependent loading scenarios. The results demonstrate the method’s capability to accurately predict the time-dependent behavior of viscoelastic trusses, addressing a significant gap in the literature by providing benchmark solutions. The proposed framework offers a computationally efficient alternative for analyzing viscoelastic structures, facilitating their integration into practical structural design and improving the prediction of long-term deformation behavior. This study provides a reliable and innovative solution for analyzing viscoelastic truss systems, making it a valuable tool for engineers and researchers working with time-dependent materials in structural applications. Full article

This article uses two case studies to promote the idea that British evangelicalism is sometimes marked by the denial of inconvenient facts. First, it takes a critical look at the apologetic impulse to explain away the problems that Scripture sometimes presents and to deny their affective dimensions. Second, it considers some of the abuse scandals of recent years and the way in which the evangelical church has tended to respond by covering them up and silencing the voices of accusers. This response appears to be motivated by the fear of quenching what appear to be successful ministries or of tarnishing the reputation of the church. The common theme that these examples share is that they are motivated by the instinct to present the gospel in the best possible light, but this appears to stem from an unarticulated functional atheism that does not truly trust God’s people to the Spirit. As a remedy, two linked practices are proposed, drawing on the work of Eugene Peterson and Cheryl Bridges-Johns. These are Sabbath-keeping as a means of rediscovering the primacy of God’s presence and work; and the re-enchantment of Scripture by means of a Pentecost imaginary, which offers the possibility for the transrational. Full article