Search Results (735)

P-wave velocity is a non-destructive test (NDT) used directly and indirectly in different disciplines. In recent years, portable equipment that can indirectly ascertain P-wave velocity has gained popularity for in situ measurements across multiple disciplines, including archeology, geology, and civil engineering. As the sample size effect has not been previously researched for portable indirect P-wave velocity (V_PI) measurement devices, this study researched the size-factor effect in magmatic rocks commonly used as building stones. Within this scope, 684 prism samples with 2 × 2, 3 × 3, 4 × 4, 5 × 5, 6 × 6, and 7 × 7 cm² square basal area and height of 17 cm, and 190 (38 × 5) cube samples with a side length of 7 cm were prepared from 38 different rocks (plutonic, volcanic, pyroclastic, and sedimentary). The variations in indirect P-wave velocity (V_PI) were experimentally determined on prismatic samples with different base areas. According to the results, the optimum sample cross-sectional area where the indirect P-wave velocity value did not change was determined to be 6 × 6 cm². Furthermore, the direct P-wave velocity (V_PD) values of the rocks were determined using cubic samples. The simple regression relationship between V_PD and V_PI measurements was investigated, and a very strong positive linear correlation (R² = 0.966) was identified. Full article

The work environment in automated laboratories and industrial sites exposes workers to the risks associated with chemical gas and vapor leaks caused by unforeseen incidents. Such leaks may result in severe health hazards as well as damage to equipment or infrastructure at the leak site. Therefore, the development of systems capable of early detection and highly accurate localization of chemical leaks is of high importance for occupational safety. In this work, a low-cost, portable sensor node based on the Internet of Things (IoT) is proposed for the detection and localization of gas and chemical leaks in indoor environments. The sensor node features a modular design that enables flexible integration and replacement of gas and environmental sensors depending on the target application. In addition, the system includes an ultra-wideband (UWB)-based positioning and tracking unit, allowing operation across multiple indoor zones. The main contribution of this work lies in the combined integration of (i) multi-sensor-based environmental event detection and prediction and (ii) high-precision location within a dynamic multi-zone tracking architecture. The system automatically selects the most relevant anchors in each zone and applies trilateration and least-squares estimation, enhanced by Kalman filtering techniques. In particular, an extended Kalman filter (EKF) and an unscented Kalman filter (UKF) are employed, with sensor fusion incorporating inertial measurement unit (IMU) data to mitigate the effects of on-line-of-sight (NLoS) conditions and signal degradation caused by obstacles. Experimental results demonstrate that both the EKF and UKF significantly reduce positioning errors and improve tracking stability compared to baseline methods under challenging indoor conditions. The UKF shows superior performance in highly nonlinear scenarios. A quantitative evaluation using manually surveyed reference points showed that the UKF achieved the best overall performance, with a mean error of 39.72 cm and an RMSE of 43.03 cm. These findings confirm the effectiveness of Kalman filter-based sensor fusion for reliable indoor positioning and highlight the suitability of the proposed system for real-time safety monitoring applications. Full article

Background/Objectives: Rapid identification of foodborne pathogens is of high practical significance because it enables prompt epidemiological response, timely patient management, and effective sanitary control of food products. In this study, we developed an integrated molecular platform combining recombinase polymerase amplification (RPA) with CRISPR/Cas12a technology for rapid, sensitive, and specific detection of Salmonella enterica. Methods: Four virulence genes (sirA, stn, siiD, and pagN) were selected as targets to ensure reliable pathogen identification. Reaction conditions were optimized using the Moraxella bovoculi Cas12a (MbCas12a) nuclease. The study focused on integrating isothermal amplification with a custom-engineered hardware solution for visual fluorescence detection. Results: The developed method demonstrated sensitive and specific detection, with no cross-reactivity to non-target microorganisms. Optimization allowed for a substantially reduced assay time of approximately 30 min. As a result, a portable fluorescence visualization approach was developed, featuring a 3D-printed housing and an integrated ultraviolet light source for direct visual fluorescence detection. This allows rapid differentiation of samples without specialized laboratory equipment, making it suitable for field applications. Conclusions: The combination of isothermal amplification, MbCas12a-based detection, and the portable fluorescence visualization approach provides a versatile platform for rapid diagnostics and food safety monitoring. This approach has strong potential to improve public health outcomes and enhance the resilience of food supply chains by enabling accessible, field-deployable pathogen detection. Full article

The impact hammer, equipped with a force transducer, is a portable and practical tool for inducing measurable excitations in structural health monitoring (SHM). However, its reliability is often limited by uncontrolled factors such as swing power, angle, impact location, and operator consistency, particularly in nonlinear structures operating at low frequencies. While many researchers have avoided hammer testing by instead using better controlled drop mass systems or operational modal analysis (OMA) techniques, this study presents a new experimental modal analysis (EMA) approach that improves the accuracy of impact hammer testing: variable impulse hammer impact testing (VIHIT) using a single-input single-output (SISO) roving hammer and single fixed accelerometer. For a mode of interest, the imaginary component of the frequency response function (FRF) is evaluated at each test location using multiple impulses of varying magnitude. This output quantity exhibits an inverse power relationship with the input autopower spectral density (APSD) at the modal frequency. Evaluating the trend at a reference input APSD from sufficiently excited tests produces a very accurate mode shape for that input. For a given structure, nonlinear damping ratios vary with excitation and can be extracted using inverse FRF analysis. This method addresses variability in impact hammer testing by establishing reproducible trends for different impulse levels and test locations. Application to degraded timber beams demonstrated reductions in mode shape variability relative to conventional averaging and revealed impulse-dependent damping ratios ranging from approximately 0.02 to 0.04, highlighting the method’s ability to characterize nonlinear dynamic behavior. The result is a more accurate approach for extracting modal properties and mode shapes and characterizing nonlinear dynamic behavior using a SISO roving impact hammer system. Full article

Building Information Modeling (BIM) has fundamentally changed the way interdisciplinary coordination works in construction projects; however, the theoretical mechanisms underlying open collaboration standards in this field remain insufficiently explored. This article fills this gap by presenting a systematic analysis of the BIM Collaboration Format (BCF) through the lens of reification and serialization, two fundamental concepts in information systems theory. Although the BCF format is widely used in the industry and implemented in major BIM tools for clash detection and issue tracking, the existing literature treats it primarily as an operational tool, overlooking the deeper information systems principles that govern its architecture. The analysis demonstrates that BCF achieves reification by transforming informal coordination knowledge—such as verbally communicated clashes, scattered email threads, and undocumented design decisions—into first-class objects (Topic, Comment, Viewpoint) equipped with unique identifiers, typed attributes, ownership, temporal metadata, and formalized inter-object relationships. Further analysis was conducted on BCF’s serialization mechanisms, including XML encoding for file exchange, JSON for RESTful API communication, and ZIP archiving as a distribution container, each of which was selected to balance human readability, schema validation, compression, and cross-platform portability. The complementarity of these two mechanisms was examined: reification determines what to preserve and in what structure, while serialization determines how to encode and in what format, which together enable interoperable, auditable, and automatable coordination workflows in heterogeneous software environments. The analysis was illustrated with a real-world BCF example from a major infrastructure project in Poland, demonstrating practical alignment between theoretical constructs and their implementation. The research results provide both a conceptual foundation for researchers working on openBIM standards and practical guidance for practitioners seeking to optimize issue management, the implementation of a Common Data Environment (CDE), and the specification of Exchange Information Requirements (EIR). The study contributes new knowledge in three areas: (1) To the best of the authors’ knowledge, it provides the first systematic theoretical analysis of BCF through the lens of reification and serialization, filling a gap between the format’s widespread practical use and its limited theoretical understanding. (2) It demonstrates how the formal criteria of reification (unique identity, typed attributes, ownership, temporal metadata, and inter-object relationships) map onto specific BCF entities, offering a transferable analytical framework for evaluating other openBIM standards. (3) It identifies the complementarity of reification and serialization as a design principle that can guide the development of future standards for digital twins and IoT-based facility management. Full article

The analysis of jaw kinematics is a valued approach to study the complex process of mastication. This review aims to provide a historically structured overview of methods used in jaw kinematic analysis, outlining their progression from early techniques to current technologies, and emphasizing key advances, limitations, and future directions. To address this aim, relevant literature was identified through targeted searches in academic databases, and key studies were used to trace earlier foundational work, allowing a historically oriented analysis of the field. The evolution of jaw kinematic methods reflects a progressive shift from subjective and indirect observations toward increasingly objective, dynamic, and three-dimensional assessments of mandibular movement. Despite substantial technological advances, many approaches remain limited by their complexity, cost, equipment size and lack of portability, and reliance on controlled laboratory environments, as well as constraints on natural movement. Nonetheless, these methods have contributed to clinically relevant insights into mandibular biomechanics and oral care, including the evaluation of different clinical conditions and treatment outcomes. Emerging technologies, including the development of more portable systems and improved motion tracking, together with artificial intelligence offer the potential of simplifying data acquisition under more natural conditions and its analysis enabling broader research and clinical use. Full article

Illyrian helmets represent a key element of Iron Age martial culture in the western Balkans, reflecting technological knowledge, workshop traditions, and long-distance cultural exchange. Based on the currently available archaeological record, Illyrian helmets are first attested in contexts dating to the 8th–7th centuries BC, with finds concentrated in Greece and the central and western Balkans, including Macedonia, Albania, Dalmatia, and the wider interior. Over time, the form developed into several variants (Types I–IIIB). This study presents the elemental characterization of the total set of 27 Illyrian helmets excavated in Albania and currently preserved in local museum collections, a region where the later types are particularly well attested. As the helmets are intact and exhibited in museums, portable in situ XRF analysis was employed. The main research questions addressed how the alloy composition, including minor and trace elements, reflects local metallurgical practices and distinguishes Illyrian helmets from similar helmets in neighboring regions. The results indicate the consistent use of bronze alloys dominated by copper (89–95%) with low- to medium-tin contents (3.5–9.9%), consistent with established alloying practices for durable protective equipment. Minor and trace elements, including iron (up to 1.5%), lead (up to 0.76%), arsenic (up to 0.09%), zinc (up to 1.17%), and antimony (up to 2.36%), likely reflect metallurgical choices, recycling practices, or impurities linked to regional copper deposits. Principal Component Analysis of four retained components, collectively accounting for 88.5% of the total variance, confirms a broadly standardized bronze tradition, with compositional outliers suggesting locally variable ore sources or recycling rather than systematic typological change. These elemental signatures, particularly the association of arsenic, antimony, zinc, and iron, suggest regional metallurgical characteristics consistent with Albanian sulphide ore deposits, while the overall compositional homogeneity supports the hypothesis of centralized production at workshops such as Epidamnus and Apollonia. Full article

Background: Outdoor time in early childhood education and care (ECEC) settings provides important opportunities for children’s physical activity. Evidence is limited on whether different organizational outdoor conditions influence not only activity intensity but also the contextual characteristics of children’s movement. Methods: An observational study was conducted using the Observational System for Recording Physical Activity in Children—Preschool Version (OSRAC-P). The study was conducted in two public ECEC centers. Not all children were observed across all three conditions due to the field-based design. A total of 7440 observation intervals were analyzed from preschool children across three outdoor conditions (structured educator-led physical activity, outdoor free play, and outdoor free play with additional portable equipment) using a momentary time-sampling protocol (10 s observation + 50 s recording), resulting in one interval per minute. Physical activity intensity, activity type, equipment use, and social context were coded. Contextual differences were analyzed using chi-square tests with standardized residuals, and activity intensity using linear mixed-effects models. Results: No significant differences were found between outdoor conditions in physical activity intensity, sedentary behavior, and moderate-to-vigorous physical activity (all p > 0.05). About one-third of the variance in activity intensity was attributable to individual differences between children (ICC ≈ 33%). Differences were observed in contextual characteristics. Structured activity involved more locomotor activities and greater adult involvement, with 49.4% of intervals occurring in groups with an educator present. Free play with portable equipment showed more manipulative activities, greater equipment use, and mostly peer interactions without adult presence (55.5%), while free play without additional equipment involved more stationary behavior and activities without equipment (46.9%). Conclusions: Although physical activity intensity did not differ across conditions, the structure, material context, and social organization of children’s activity varied, highlighting the practical importance of intentionally combining different outdoor activity formats to support diverse movement patterns in ECEC settings. Full article

To evaluate the performance of a printed log-periodic dipole antenna (PLPDA) in outdoor environments, we present unmanned aerial vehicle (UAV)-based antenna measurements conducted in the far-field region. Non-tethered UAV flight operations were achieved by configuring commercially available UAVs separately as a transmitter (TX) and as a receiver (RX). UAVs configured in non-tethered mode provide flexibility in terms of altitude maintained by the UAV from the ground level. The TX section of the UAV consists of a portable signal generator and a PLPDA configured to transmit signals with an output power of +15 dBm at 0.8 and 3.5 GHz. Similarly, the RX section of the UAV is equipped with a real-time spectrum analyzer and an identical PLPDA. Using these two UAVs in TX and RX modes, the radiation pattern of the PLPDA was obtained in the azimuth plane. Since two identical PLPDAs were used, the realized gain of the PLPDA is evaluated using the two-antenna gain method. The test scenario involved the TX UAV hovering at the center while the RX UAV followed a circular trajectory around it. A comparison between the UAV measurements, anechoic chamber measurements, and simulated data demonstrates good agreement, validating the reliability of the measurements. Full article

Chitooligosaccharides (COS) are short-chain chitosan derivatives with a wide range of biomedical, agricultural, and environmental applications, including antimicrobial therapy, wound healing, and pollutant removal. Reliable quantification of COS is essential but currently relies on high-performance liquid chromatography, mass spectrometry, or capillary electrophoresis, which require costly equipment, complex sample preparation, and are unsuitable for routine or on-site applications. This study reports a rapid, solvent-free, colorimetric assay for COS based on the reaction of 5% aqueous ninhydrin with free amino groups in McIlvaine buffer. The assay was optimized using glucosamine as a model analyte, yielding maximal sensitivity at pH 7.0. The chromophore generated (Ruhemann’s purple) remained stable for over 120 min after reaction, allowing measurements to be taken without strict time constraints. Calibration was linear from 0.4 to 2.2 mM (R² = 0.9926), with low limits of detection (0.006 mM) and quantification (0.018 mM). Increasing absorbance with COS polymerization degree (DP1–DP6) demonstrates specificity for free amino groups, while N-acetyl glucosamine showed a negligible response. Furthermore, the assay was successfully adapted for solid-phase detection on ninhydrin-pretreated filter paper and nitrocellulose, with enhanced sensitivity. This simple, efficient, and low-cost method provides an accessible alternative to instrumental techniques, supporting COS monitoring in laboratory workflows and enabling portable applications in biomedicine, agriculture, and environmental diagnostics. Full article

Abandoned mining areas provide valuable opportunities to investigate ore-forming processes, supergene mineral transformations, and the geochemical behaviour of metals. In this sense, the old Preguiça mine (Beja, Portugal), exploited for Fe–Zn–Pb, was studied providing new mineralogical and geochemical data aimed at improving the understanding of the secondary mineral assemblages of this deposit. A total of 70 samples collected from three accessible underground levels (first, second and third) and mine waste, complemented by 16 samples from a deeper level (fourth) previously collected, were analysed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and a portable X-ray fluorescence (pXRF) equipment. Mineralogical phases are dominated by a wide range of secondary oxides, carbonates, arsenates, vanadates, silicates, phosphates and sulphates, but remnants of primary sulphides were also found. The following minerals can be emphasised: goethite, hematite, calcite, dolomite, descloizite, willemite, mimetite, cerussite, smithsonite and fraipontite. The presence of massicot in the Preguiça mine, is described for the first time. Bulk geochemical analyses show high concentrations of Fe, Ca, Zn and Pb, consistent with the observed mineralogy. The presence of vanadium- and arsenic-bearing minerals highlights the occurrence of critical raw materials, supporting the importance of reassessing other abandoned mining areas in the context of sustainable resource management and strategic raw-material planning. Full article

The detection of plastic explosives in vapor form is extremely challenging due to the very low volatility of their primary components, such as RDX and PETN. To overcome this limitation, volatile chemical markers like 2,3-dimethyl-2,3-dinitrobutane (DMNB) are added to explosive formulations to enable indirect vapor detection. This study presents a rapid method for detecting and quantifying DMNB vapors using a handheld ion mobility spectrometer (IMS) operating near ambient temperature, ammonia-doped and equipped with a non-radioactive corona discharge ionization source. The instrument, model LCD-3.2E (Smiths Detection Ltd.), is based on a twin drift–cell time-of-flight configuration and simultaneously records ion mobility spectra in both positive and negative modes. DMNB generated distinct product ion peaks in both modes, with reduced mobility values (K₀) of 1.42 cm²V⁻¹s⁻¹ (positive) and 1.37 cm²V⁻¹s⁻¹ (negative). The method demonstrated high sensitivity, with limits of detection calculated at 1.4 ppb_v (10.2 × 10⁻³ mg m⁻³) in positive mode and 3.1 ppb_v (22.7 × 10⁻³ mg m⁻³) in negative mode. The IMS system provided rapid responses within seconds and covered a quantifiable concentration range of 5–3000 ppb_v, with saturation estimated to appear above approximately 5 ppm_v (36.6 mg m⁻³). The simultaneous dual-polarity response of the DT IMS enhances both the selectivity and reliability of identification. These findings confirm the capability of portable IMSs for fast trace vapor detection in DMNB, supporting its application in field-based screening scenarios such as luggage inspection or container interrogation, where indirect detection of plastic explosives is required. Full article

To address the issues of operational complexity, long duration association, and reliance on specialized equipment with existing detection methods for Vibrio parahaemolyticus, this study established a rapid detection method for V. parahaemolyticus in exported aquatic products based on the domestically developed Enzymatic Recombinase Amplification (ERA) technology. To target the thermolabile hemolysin gene (tlh) and the iron-regulated virulence regulatory protein gene (irgB) of V. parahaemolyticus, highly specific ERA primers and probes were designed and screened. Two detection platforms, a colorimetric method and a fluorescent method, were developed. Method validation results showed that this detection system achieved specific amplification for all 30 tested V. parahaemolyticus strains, with no cross-reactivity observed with 30 other common foodborne pathogenic bacteria. The detection sensitivity for both the fluorescent and colorimetric methods reached 10⁻¹ ng/μL, with a minimum detection limit of 10 CFU/25 g for artificially contaminated samples. The entire detection process, including sample preparation, requires only approximately 20 min—significantly faster than traditional culture (24–72 h) or even conventional PCR methods. Collaborative validation across five independent laboratories confirmed excellent reproducibility, with inter-laboratory agreement yielding a Kappa coefficient of 0.98. The ERA method operates at a low, constant temperature (37–39 °C), eliminating the need for thermal cyclers. When combined with portable isothermal amplification devices and visual (colorimetric) readout, it offers a distinct advantage in terms of speed, cost-effectiveness, and suitability for resource-limited or field settings compared to existing PCR-based or culture-based platforms. This method is simple to operate, rapid, sensitive, and highly suitable for on-site application, providing a reliable and practical technical solution for the rapid screening and risk monitoring of V. parahaemolyticus in exported aquatic products. Full article

To address the practical requirements for in situ equipment restoration, this study investigates a portable and cost-effective approach for the localized repair of SAE 10SAE 1045 components using a 1Cr13 martensitic stainless steel coating prepared via an arc-based additive manufacturing (WAAM) process. The microstructural evolution and tribological response of the layers were analyzed, with a focus on the effects of discrete thermal cycling and controlled solidification inherent to portable arc equipment. The WAAM process produced a refined martensitic matrix with a microhardness of 551.94 HV0.2, which is 2.26 times that of the substrate. Under dry sliding conditions, the 1Cr13 coating exhibited a lower friction coefficient and a reduced wear volume compared to the untreated SAE 1045, primarily through the mitigation of severe plastic deformation. This additive route provides a millimeter-scale reinforcement layer with metallurgical integrity suitable for heavy-duty service, aiming to offer a practical reference for the low-cost, on-site restoration of industrial components. Full article

Stroke survivors with spasticity, an involuntary increase in muscle tone, often struggle to access specialized equipment and medical support for their rehabilitation. Rehabilitation exercises are daily routines requiring patients to perform repetitive movements of their spastic joints. To reduce patient mobilization within hospitals, offering orthoses suitable for use in home settings, outside of clinical environments, is required to limit the involvement of healthcare personnel in the treatment of hemiparesis for patients. Such orthoses must be designed to be portable and be able to tolerate the erratic motions of spasms without breaking or injuring patients. This paper presents the use of magnetorheological actuators to design an elbow orthosis, improving weight, reactivity, and transparence necessary for effective rehabilitation of spastic patients. A prototype is designed, built, and characterized experimentally. Results suggest that the technology is lightweight and highly transparent to erratic motion, and thus well-suited for spastic patients. Full article