Search Results (6,763)

Graphite nozzles remain the dominant choice for small hybrid and solid rocket motors operating on laboratory and university budgets, owing to their low cost, ease of machining, and rapid turnaround during iterative design campaigns. These same programs, however, must contend with the fact that graphite erodes through coupled thermochemical and mechanical mechanisms when exposed to the oxidizing species generated by high-energy propellant combustion, and the resulting throat-area growth fundamentally alters the time histories of chamber pressure, thrust, and delivered specific impulse. This paper presents a nozzle-erosion reconstruction model that extracts the time-resolved throat area from coupled thrust and chamber-pressure measurements using the thrust coefficient relationship, scales the reconstructed area history against pre- and post-test throat measurements, identifies the onset and rate of erosion, and accounts for variable sensor lag between the thrust-stand and pressure-transducer signal chains. The model is exercised on two complementary sets of laboratory-scale GOX/ABS hybrid hot-fire data that together span roughly two orders of magnitude in total throat-area change and peak chamber pressures from 0.5 to 3.4 MPa: a controlled three-operating-point campaign conducted in support of the NASA Plume-Surface Interaction (PSI) program, and a set of higher-pressure firings from the laboratory development series in which the technique was matured. Reconstructed erosion-onset times, erosion rates, and total throat-diameter change are reported for each firing, the reconstruction accuracy is characterized as a function of erosion magnitude. A correlation of graphite erosion with chamber pressure is examined across the combined envelope. The results demonstrate the robustness of the reconstruction technique and provide a reusable framework for post-test reconstruction of transient nozzle geometry in rocket-engine ground testing. Full article

The global water situation is deteriorating not only due to the progressing climate change but also to irrational consumer behaviors, which are driven by attitudes. Given the above, it seemed essential to identify attitudes toward the issue of access to freshwater in households, considering sustainable development guidelines. The aim of this study was, therefore, to develop a research tool for the identification of respondents’ attitudes toward this problem and then to determine its validity and reliability. The object of the study was an original questionnaire serving as a research tool for identifying the specified attitudes. The data required for this study were acquired through a critical review of the literature and a questionnaire survey method. The study was conducted in one of the Polish urban agglomerations using the Paper-and-Pencil Interviewing (PAPI) technique. An in-depth analysis of the validity and reliability of the tool, carried out using a statistical procedure, confirmed it to be a viable means to identify these attitudes in Poland. Therefore, there are reasonable grounds to assume that, following the application of the procedure presented in this manuscript, the developed tool may also be used to identify the specified attitudes when implemented in a different population. Full article

Background: Contraceptive counseling is a critical component of reproductive healthcare, directly influencing method uptake, continuation, and user satisfaction. While global health guidelines increasingly emphasize person-centered, rights-based approaches to counseling, wide variations in practice persist, with significant implications for equity and autonomy. Objective: This narrative review aims to synthesize current evidence on the strengths, limitations, and future opportunities of contraceptive counseling within person-centered care frameworks, with particular attention to adolescents and other populations facing structural or sociocultural barriers to equitable care. Methods: A comprehensive literature search was conducted across six indexed databases (PubMed, Scopus, Embase, Web of Science, CINAHL, and PsycINFO) for peer-reviewed articles published between January 2010 and April 2025. Eligible studies included original quantitative, qualitative, and mixed-methods research examining contraceptive counseling practices, user experiences, provider–client communication, counseling interventions, or implementation strategies in reproductive healthcare settings. Results: Emerging strengths in the field include the increasing adoption of shared decision-making, motivational interviewing, and culturally tailored counseling approaches, all of which contribute to improved client satisfaction and method adherence. Digital tools and mHealth platforms have expanded the reach of counseling and show promise in supplementing in-person care. However, significant gaps remain. Provider bias, limited training, communication barriers, and a lack of socio-cultural tailoring frequently undermine the quality of care, especially for adolescents, migrants, women with disabilities, and socially vulnerable populations. Ethical challenges—such as coercion, inadequate informed consent, and structural inequities—persist in many healthcare settings. Moreover, contraceptive counseling is often treated as a one-time event rather than an ongoing, adaptive process. Conclusions: To maximize its impact, contraceptive counseling must be reframed as a longitudinal, relational, and ethically grounded practice. Future efforts should prioritize the development of structured training programs, integration into broader health services, and qualitative research that centers patient experiences. Embedding counseling within reproductive justice frameworks will be essential for advancing equity and autonomy. High-quality contraceptive counseling, when informed by evidence and empathy, is a strategic tool for reproductive empowerment and public health advancement. Full article

Train-induced vibrations pose a significant threat to foundation pit slopes adjacent to railways during parallel construction or line renovation projects. To address this issue, this paper proposes a periodic steel-sheet pile barrier for vibration mitigation in narrow construction sites. Firstly, field tests were conducted along the Qinbei Railway in China. The acceleration time history and dominant frequency (27.6 Hz) of ground vibrations were obtained. Secondly, based on periodic structure theory, the dispersion relations and band-gap characteristics of periodic steel-sheet piles were analyzed using the finite element method. Parametric studies were then performed to investigate the effects of key factors, including periodic constants, pile spacing and pile count per unit cell, and construction deviations, on the band-gap boundaries and width. Subsequently, frequency-domain, time-domain, and slope stability analyses were carried out to evaluate the isolation performance. The results show that the optimized barrier, with parameters of a = 1.6 m, D = 0.1 m, n₁ = n₂ = 4, and L = 2S, reduced the peak acceleration by 70% and achieved a vibration reduction of up to 88% at the dominant frequency. Furthermore, slope stability analysis revealed that the barrier increased the factor of safety from 1.16 to 1.46, exceeding the code-required minimum of 1.2–1.3. This study provides a potentially cost-effective and construction-friendly solution for protecting temporary foundation pit slopes from train-induced vibrations in railway-adjacent areas. Full article

Accurate extraction of transmission towers from Unmanned Aerial Vehicle (UAV) Light Detection and Ranging (LiDAR) point clouds is a prerequisite for overhead transmission line (OTL) acceptance. This task remains challenging because tower points are heavily entangled with ground, vegetation, conductors, and insulators, especially in complex terrain. To address this issue, we propose a shape prior-guided coarse-to-fine framework for tower extraction from UAV LiDAR point clouds. First, candidate tower regions are localized from the scene point cloud through preprocessing, near-ground suppression, and density-based clustering. Second, the least-disturbed central body of each candidate tower is identified in a slice-wise manner and used to estimate the tower orientation and four principal structural axes. Third, side-view and front-view structural envelopes are progressively inferred to suppress non-tower points around the tower body and tower head. Finally, a base-constrained filtering strategy is introduced to remove residual ground and low-vegetation points within the tower footprint. Experiments conducted on multiple OTL datasets acquired in different regions of China, including plains and mountainous areas, demonstrate that the proposed method achieves robust and efficient tower extraction across diverse scenarios. The results indicate that explicit structural priors offer a promising complement to feature-driven and data-intensive approaches, particularly in scenarios with limited annotated data and strict real-time requirements. The proposed method processes scene point clouds containing tens to hundreds of millions of points, with an average extraction time of approximately 100 to 300 s per tower depending on scene density. Full article

High-speed railway embankments constructed over karst-prone ground conditions are often challenged by weak soils and subsurface cavities, which can lead to instability and excessive settlement. This study presents a full-scale field investigation conducted in the El-Gharbaniyat area, west of Alexandria, Egypt, where a pile–cap ground improvement system was implemented to support a high-speed railway embankment founded on clayey and silty soils overlying fractured limestone. A comprehensive site investigation program was performed, including 28 boreholes and integrated geophysical surveys using Electrical Resistivity Tomography (ERT) and Seismic Tomography (ST), enabling improved identification of weak zones and cavity-prone formations. Based on these findings, a pile–cap system was designed using reinforced concrete piles of 0.60 m diameter and an average length of 29 m, arranged in a 4 × 4 m grid and capped with reinforced concrete footings to ensure efficient load transfer to deeper competent strata. The system performance was validated through laboratory testing and full-scale in situ pile load tests. The average 28-day compressive strength of 122 tested piles reached approximately 50 MPa, exceeding the design value by approximately 30%. Load test results showed settlements ranging from 1.08 to 2.76 mm at the working load (2200 kN) and 2.16 to 5.10 mm at the maximum load (3300 kN), all well below allowable limits. Comparative evaluation indicated that the proposed system achieves significant material savings (>90%), lower treatment cost (150 USD/m²), reduced carbon emission (5.7 t per pile), and shorter construction duration (7 h per pile). These findings confirm that the pile–cap system provides a robust, cost-effective, and environmentally efficient solution for ground improvement in karst environments. Full article

The rapid advancement of machine learning and artificial intelligence (AI) has created new opportunities to enhance diagnostic accuracy in dermatology, particularly within primary care settings. Computer-aided diagnosis (CAD) systems have demonstrated potential to support General Practitioners (GPs) by enabling earlier and more consistent identification of skin diseases. This review critically examines the literature on explainable artificial intelligence (XAI) for skin disease classification, with a specific focus on the evolution of explainability frameworks and the methodological implications of dataset selection. A comprehensive review of studies published between 2020 and 2025 was conducted across multiple academic databases, encompassing research on skin lesion detection, classification, and monitoring. The analysis reveals that deep learning architectures, particularly those leveraging transfer learning with models such as EfficientNet, ResNet, and Xception, frequently report high classification accuracies—often exceeding 90% when evaluated on single benchmark datasets. However, studies employing multiple datasets consistently demonstrate more stable and generalisable performance, albeit with modest reductions in reported accuracy, highlighting a critical trade-off between performance optimisation and real-world robustness. The review further identifies a clear temporal progression in the adoption of XAI techniques. Early studies relied on a broader range of post hoc explainability while later work increasingly consolidated around Grad-CAM, SHAP, and related attribution techniques, followed by gradual diversification into more specialised frameworks such as TCAVs (Testing with Concept Activation Vectors) and Prototype-based Networks. Despite these advances, the lack of clinically grounded explanations, limited integration of ethical considerations, and reliance on non-clinical imagery continue to constrain clinical applicability which we have explored using a GRADE-style narrative. Notably, evidence suggests that CAD systems can improve GP diagnostic accuracy for conditions such as melanoma and seborrhoeic keratosis; however, sustained clinical adoption remains contingent on transparent, reliable, and context-aware explainability mechanisms. Full article

Background and Objectives: Low participation rates in exercise programs among older adults highlight the need for theory-driven, biopsychosocial interventions that enhance adherence, self-efficacy, and functional outcomes. Grounded in principles of motor learning and behavioral reinforcement within physiotherapy practice, this study aimed to examine the effect of periodic assessments combined with verbal feedback on functional and psychological outcomes in community-dwelling older adults. Methods: A pilot RCT was conducted involving 54 individuals aged ≥65 years (53 women and 1 man), recruited from senior community centers. Participants were randomly allocated to an intervention group (periodic assessment and verbal feedback; n = 27) or a control group (n = 27). Both groups participated in an identical 12-week structured exercise program, delivered twice weekly, focusing on balance, gait, and lower-limb functional training. An intention-to-treat approach was applied. Data were analyzed using Linear Mixed Models, with statistical significance set at p < 0.05. Results: Significant group × time interactions were observed in favor of the intervention group for key kinesiology-related functional outcomes, including the Short Physical Performance Battery (SPPB; p < 0.001), Timed Up and Go test (TUG; p = 0.011), and Activities-specific Balance Confidence Scale (ABC; p < 0.001). No statistically significant differences were identified between groups for the Behavioral Regulation in Exercise Questionnaire–2 (BREQ-2; p = 0.164) and the Self-Efficacy for Exercise Scale (ESE; p = 0.108), indicating that the primary psychological outcome (ESE) was not confirmed. However, both ESE and BREQ-2 demonstrated significant baseline differences favoring the intervention group, and, therefore, these findings should be interpreted with caution despite statistical adjustment. Conclusions: Periodic assessments followed by verbal feedback appear to selectively improve the functional effectiveness of structured exercise programs in older women, particularly physical performance, functional mobility, and balance confidence, with no significant differential effect on the primary psychological outcome (ESE; group × time interaction: p = 0.108). These findings support assessment-informed and feedback-driven physiotherapy strategies as a promising adjunct to exercise programs in older adults, with potential implications for optimizing functional outcomes within applied kinesiology and rehabilitation contexts. Full article

Although considerable research has investigated non-motorized treadmills (NMTs), most studies have focused on healthy adults or athletes. This study aimed to compare trunk and lower limb muscle activation during walking on an NMT and flat ground (FG) at different exercise intensities in patients with stroke. Eighteen patients with stroke participated in this within-subject, repeated-measures experimental study conducted at a single hospital. Participants performed walking trials under six randomized conditions, comprising both NMT and FG walking at intensities of 20%, 40%, and 60% of heart rate reserve (HRR). Muscle activation of the affected-side erector spinae, internal oblique, gluteus medius, gluteus maximus, vastus medialis oblique, biceps femoris, and lateral gastrocnemius was assessed. Walking on the NMT resulted in significantly greater overall muscle activation than walking on FG (p < 0.05). In addition, significant differences in trunk and lower limb muscle activation were observed across HRR levels during both NMT and FG walking (p < 0.05), indicating that exercise intensity influenced neuromuscular responses. These findings suggest that NMT walking, particularly at higher intensities, acutely increases neuromuscular demands, providing preliminary evidence for its potential application as a demanding walking condition for stroke rehabilitation. Full article

The transition to university is a critical period of academic, social, and emotional adjustment. Social media plays a central yet complex role, offering opportunities for connection while also posing risks to wellbeing, productivity, and social integration. This study explores how first-year undergraduates experience and interprets their social media use during this transition. Using a constructivist grounded theory approach, nine focus groups were conducted with 40 first-year students at a UK university. Analysis generated a model conceptualising social media as a ‘double-edged sword’ within the broader social transition. Five interrelated themes were identified: social transition, polarised attitudes, quality of social connection, wellbeing support, and quantity and form of use. Social media supported early connection-building, maintaining peer ties, and accessing support, yet excessive or passive use intensified social comparison, fear of missing out, and academic distraction. Students recognised problematic use themselves, often prompting peer intervention to restore balance. Form, purpose, and perceived impact shaped experiences more than time spent. Findings highlight the importance of student agency, peer networks, and institutional support, offering implications for promoting healthy social media practices, wellbeing, and smoother transitions to university life. Full article

With the increasing availability of high-resolution (<50 m) spaceborne night time light imagery, it is now becoming more feasible to examine the correspondence between spaceborne and ground-based measurements of night lights. However, so far there have been very few studies that have conducted a ground-based campaign of night time brightness measurements during the overpass of a night light-sensitive satellite. Here we tested whether the correspondence between measurements is higher when ground-based measurements are conducted at the same time as the satellite overpass. We conducted measurements using a LANcube photometer along the same route on two consecutive nights (27–28 August 2025) in Brisbane, Australia, and compared them with an SDGSAT-1 (10–40 m) and Haishao-1 (10 m) images acquired concurrently in the evening and with an early morning ISS photo (8 m) acquired three months earlier. We found the correlation between ground-based and spaceborne measurements was not higher for simultaneous measurements, and the explanatory power of our model predicting night time brightness as measured from space increased when including horizontal and upwards ground-based brightness measurements alongside variables of canopy height, land use and road hierarchy. We confirmed the importance of multidirectional ground measurements and urban structure for understanding night time brightness levels measured from space. Full article

It is essential to exercise control over the environmental impact of deep excavation construction in soft soil areas from the perspective of deformation in order to ensure engineering safety. A three-dimensional finite element model of the foundation pit was developed, thereby creating a comparison between the results of the numerical simulation and the actual on-site monitoring data. This process served to validate the precision of the simulations. The focal point of the study pertained to the three-dimensional effects of support structure deformation and ground settlement during excavation. A comprehensive analysis of the spatial distribution and evolutionary patterns of underground diaphragm wall deformation and ground settlement behind the wall at varying excavation depths was conducted. The results demonstrated that both support structure deformation and ground settlement behind the excavated structure exhibited substantial spatial effects. In particular, larger deformations were observed near the symmetrical plane of the excavation centre. Conversely, greatly smaller deformations were observed in the corners of the excavation. The research findings aim to provide useful references for practical engineering projects. Full article

Problem sets are widely used in economics education, but the availability of generative artificial intelligence creates new challenges for assessment validity and academic integrity. This study conducts a rating-based benchmarking evaluation of GPT-4o on introductory economics problem-set items. Using 260 rated questions and three independent instructor ratings per item, we examine how GPT-4o performance varies across discussion, numerical, graphical and mixed-modality questions. The study is descriptive rather than causal: it benchmarks GPT-4o outputs under a specified prompting, input-modality and scoring protocol. All items were submitted through the ChatGPT web interface in fresh sessions, each item was answered once, graphical items were provided through uploaded original diagram images, no follow-up prompts were used, and outputs were saved without editing. Results show that GPT-4o performs comparatively well on text-based discussion and numerical-only items, but substantially less well on graphical items, especially those requiring numerical reasoning grounded in a graph. Inter-rater reliability is high according to intraclass correlation coefficients, and pooled rater–item analyses confirm the graphical and graphical–numerical performance gap as a descriptive benchmark pattern. To improve reproducibility while respecting copyright restrictions, the revised manuscript specifies the prompting protocol, coding procedure, rater procedure and supplementary replication files. The findings suggest that economics instructors should not simply add graphical questions as an “AI-proof” device, but should design constructively aligned, accessible, mixed-format assessments that validly sample intended economic reasoning skills. The conclusions are restricted to GPT-4o, the February–June 2025 testing window, the ChatGPT web-interface protocol and the item corpus used in this study. Full article

Background: Artificial intelligence (AI) adoption is increasingly reported as a priority for organizations, yet they face a growing, fragmented body of evidence concerning the factors that influence successful AI integration. Method: To identify the relevant factors for organizational AI adoption, we conducted a systematic literature review (SLR) following PRISMA guidelines, which yielded 37 quantitative empirical studies. From these studies we extracted 1229 paper-item instances, of which 810 were retained after applying structured exclusion criteria to develop a domain model relevant to organizational AI adoption. The model’s content validity was assessed and supported through expert feedback using the Content Validity Index (CVI) methodology. Results: We organized 24 subclusters into nine main clusters across the three dimensions Technology (Enablers, Usability, Trust), Organization (Leadership, People, Process), and Environment (Market, Regulatory, Partner). Our analysis suggests that workforce skills, perceived intelligence, and resources are among the most frequently studied and positively associated antecedents of AI adoption, and that constructs related to AI explainability and control (human-in-the-loop oversight) have received little research attention and remain underrepresented despite growing regulatory requirements such as the EU AI Act. Conclusions: The resulting domain model provides an empirically grounded classification of organizational AI adoption factors and can serve as a foundation for future measurement instruments. Full article

Background/Objectives: Wheelchair users with multiple sclerosis (MS) often face barriers that restrict participation in physical activity and exercise training. This manuscript reports on participant feedback to guide evaluating and refining a novel exercise training program, Seated Physical activity INtervention (SPIN). SPIN was adapted from the Guidelines for Exercise in MS (GEMS) approach using a three-step community-engaged research framework based on meeting the needs of wheelchair users with MS. Methods: Semi-structured interviews were conducted with 9 participants who completed the 16-week SPIN intervention. The key SPIN intervention components were the exercise prescription, exercise equipment, and behavioral coaching grounded in Social Cognitive Theory. Formative interview domains included overall experience, enjoyable and missing components, delivery modifications, barriers, lessons learned, and additional research topics of interest. Data were analyzed and reported using a rapid qualitative analysis approach. Results: Interviews averaged 16 ± 10 min. Participants reported enjoying SPIN, noting program strengths as being flexible and appropriate for individuals with MS, receiving coaching calls by knowledgeable staff that offered support and accountability, and receiving exercise equipment and video demonstrations. Participants also identified strategies for enhancing the program such as including peer support, offering real-time feedback during exercise, and adding other wellness behavior topics (e.g., diet). Conclusions: The results offer helpful ideas to consider when developing exercise training programs for wheelchair users with MS and other disabilities that may improve health and well-being. Full article