Search Results (4,138)

Underground mine emergencies destroy communication infrastructure when situational awareness is most critical. Current systems rely on centralized network infrastructure, which fails during emergencies when miners are trapped and require rescue coordination. This paper proposes an energy-harvesting LoRa mesh network that addresses self-powered operation, interference management, and adaptive physical layer optimization under severe underground propagation conditions. A dual-antenna architecture separates RF energy harvesting (860 MHz) from LoRa communication (915 MHz), enabling continuous operation with supercapacitor storage. The core contribution is a decentralized scheduler that derives optimal timing offsets by modeling concurrent transmissions as a Poisson collision process, exploiting LoRa’s capture effect while maintaining network coherence. A SINR-aware physical layer adapts spreading factor, bandwidth, and coding rate with hysteresis, controls recomputing timing parameters after each change. Experimental validation in Missouri S&T’s operational mine demonstrates far-field wireless power transfer (WPT) reaching 35 m. Simulations across 2000 independent trials show a 2.2× throughput improvement over ALOHA (49% vs. 22% delivery ratio at 10 nodes/hop), 64% collision reduction, and 67% energy efficiency gains, demonstrating resilient emergency communications for underground environments. Full article

Far-infrared imaging is a powerful tool in night vision and temperature measurement, with broad applications in military, astronomy, meteorology, industrial, and medical fields. However, conventional imaging lenses face challenges such as large size, heavy weight, and difficulties in miniaturization, which hinder their integration and use in applications with strict requirements for mass and volume, such as drone-based observation and imaging. To address these limitations, we designed a dual-plane diffractive optical lens optimized for the 10.9–11.1 μm wavelength band with a 0.2 μm bandwidth. By optimizing parameters including focal length, spot size, and field of view, we derived the phase distribution of the lens and converted it into the surface sag. To enhance diffraction efficiency and minimize energy loss, the lens was fabricated using a continuous phase surface on single-crystal Germanium. Finally, an imaging system was constructed to achieve clear imaging of various samples, demonstrating the feasibility of both the device and the system. This approach shows great potential for applications requiring lightweight and miniaturized solutions, such as infrared imaging, machine vision, remote sensing, biological imaging, and materials science. Full article

Ductility, as a fundamental mechanical property, allows structures to undergo inelastic deformations and dissipate seismic energy while maintaining their load-carrying capacity without substantial strength degradation. Thus, the estimation of structural ductility demand has consistently constituted an essential topic of research interest in earthquake engineering. In this study, an iterative procedure for estimating the ductility demand of elastoplastic single-degree-of-freedom (SDOF) systems through dissipated energy is introduced. The proposed procedure helps the determination of ductility demand by use of only elastic response spectra. It initially estimates the hysteretic energy as a proportion of the total input energy. Then, ductility demand is estimated with the help of a developed equation by performing regression analyses based on the nonlinear time history analyses results of elastoplastic single-degree-of-freedom (SDOF) systems with a certain strength. Time history analyses were carried out by using an extensive earthquake ground motion database, which includes a total of 268 far-field records, two horizontal components from 134 recording stations located on firm soil sites. Full article

The Two-Measure Theory (TMT) has been developing since 1998 and has yielded a number of highly interesting results, including those not realized in traditional field theory models. The most important advantage of TMT as an alternative theory is that, under the conditions under which all classical tests of general relativity are performed, TMT models are able to accurately reproduce Einstein’s general relativity. Despite this, TMT is still often perceived as something too exotic to be relevant to reality. In fact, the fundamental idea underlying TMT seems undeniable: if we truly believe in the effectiveness of mathematics in studying nature, we must agree that there must be a correspondence between the fundamental laws of nature and the structure of the mathematical apparatus necessary to adequately describe them. It then turns out that there is no reason to ignore the volume measure existing on the differentiable manifold on which the theory of gravity and matter fields is built. This idea has far-reaching implications. The goals of this paper are (1) to provide a clear mathematical and conceptual justification for TMT and (2) to collect in a single article some of the main results of TMT obtained over the past 25 years. Full article

In this paper we present a brief review of extended general relativity in four dimensions and solve versions of the extended equations for the case of static spherical symmetry in various contexts, for a previously studied Lagrangian. The exterior vacuum yields a Schwarzschild solution with an additional scalar field potential that falls off logarithmically, the latter essentially an inverse square force. That is probably not adequate as a dark matter force, but might contribute. When a constant density field of ions holds sway in the exterior, a solution identical to the cosmological constant extension of Schwarzschild occurs, together with a scalar field potential declining as $r^{-3/2}$, however it is not asymptotically flat. An inverse square declining distribution of ionic material, according to perturbation theory, results in an additional linear gravity potential that would provide further attraction in the gravity term. A limited exact solution in the same case yields a cubic equation with a Schwarzschild solution, corresponding to $A=0$, and two MOND-like possible potentials, one vanishing at infinity, but a better solution must be found. The approximate solution is complex (one of many) and the system requires further study. Ionic matter is ubiquitous in the universe and provides a source for the scalar field, which suggests that the extended Einstein equations could be of utility in the dark matter problem, provided such an electromagnetic scalar force could be found and differentiated from the usual, far stronger electromagnetic forces. Further, it’s possible that the strong photon flux outside stars might have an influence, and is under current investigation. These calculations show that extending the concept of curvature and working in four dimensions with larger operators may bring new tools to the study of physics and unified field theories. Full article

Background: Mandibular canal (MC) variants are common and clinically relevant for anesthesia, implant placement, third-molar surgery, and osteotomies. Reported prevalences vary widely because they depend on imaging modality, acquisition parameters, and operational definitions. Methods: This was a focused narrative review with structured methods (PubMed/MEDLINE and Scopus, 2000–6 October 2025; last search 6 October 2025), predefined eligibility criteria and dual independent screening; no meta-analysis was conducted. Study-selection counts are reported in the text. Prevalence statements are contextualized by modality, imaging parameters (e.g., cone-beam computed tomography (CBCT) voxel size magnetic resonance imaging (MRI) field strength/sequences), and diagnostic thresholds (e.g., anterior loop (AL) criteria). Results: Compared with panoramic radiography (PR), CBCT consistently reveals more variant pathways. Typical CBCT estimates for bifid MC fall in the single-digit to low double-digit range, contingent on voxel size and definitions, whereas PR detects far fewer. Trifid canals are uncommon (≈1–2% in CBCT series). Reported retromolar canal frequencies vary broadly across populations and protocols, and AL length and prevalence are threshold-dependent. Selective MRI may complement CBCT by depicting soft-tissue branches not accompanied by a bony canal. We synthesize a variant-aware, imaging-led workflow: PR for screening; CBCT when predefined criteria are met and results are reasonably expected to change management; MRI reserved for targeted soft-tissue questions, in line with As Low as Reasonably Achievable (ALARA)/and As Low As Diagnostically Acceptable (ALADA) principles. We apply the Landfald Clinical Framework (LCF) as a hypothesis-generating, clinical synthesis tool linking variant patterns to procedural modifications and risk mitigation. Conclusions: A narrowed, clinically oriented approach—contextualizing prevalence by modality and definitions and applying an imaging-led, variant-aware workflow—can improve planning and safety in the posterior mandible. The LCF is used pragmatically within this workflow and does not constitute a new anatomical taxonomy; formal reliability and validity testing remain necessary. Full article

Near-fault ground motions significantly threaten bridges due to their distinct features, which are often inadequately considered in current seismic codes based mainly on far-field records. This study analyzes 941 near-fault records to evaluate the effects of site class, pulse-like motions, and vertical components on the peak acceleration ratio and normalized response spectra. A finite element model of a typical simply supported girder bridge is developed to examine how these factors affect pier internal forces. Results show that the peak acceleration ratio increases with softer sites and exhibits large scatter in near-fault regions, indicating that the conventional vertical-to-horizontal ratio of 0.65 may significantly underestimate vertical seismic actions. Pulse motions shift and broaden response spectra, raising seismic demands for medium- to long-period structures. Additionally, pulse effects combined with soft sites cause coupled amplification of internal forces. This work offers a theoretical basis for seismic design and assessment of similar bridges. Full article

This paper presents the design and fabrication of a 1.65 μm tapered semiconductor laser based on an InGaAlAs multiple quantum well structure (grown) on InP. Through theoretical modeling and parametric optimization simulations, it was established that an etching depth of 0.8 μm for the ridge waveguide and a taper angle of 6° effectively confine the optical field and suppress high-order mode lasing. Based on these optimized parameters, a tapered semiconductor laser with a ridge width of 2 μm and a cavity length of 2000 μm was successfully fabricated. Systematic characterization was conducted under continuous-wave operation at 25 °C. The device exhibits outstanding overall performance: a maximum continuous-wave output power of 19.3 mW, a peak wavelength of 1653 nm, a spectral line width of 0.793 nm, and a side-mode suppression ratio (SMSR) as high as 49 dB, demonstrating excellent spectral purity. Far-field measurements further reveal that at an injection current of 30 mA, the vertical and horizontal far-field divergence angles are 41.02° and 15.26°, respectively, with a well-defined Gaussian beam profile. This study provides an effective technical approach for the design and fabrication of high-performance semiconductor lasers in the 1.65 μm band. The developed device shows significant potential for applications in free-space optical communication, LiDAR, and gas sensing. Full article

Harmonic-assisted phase amplification was investigated in a 300-µm-thick Nd:GdVO₄ laser with coated end mirrors in the self-mixing interference scheme. The key event is the self-induced hybrid skew cosh Gaussian (abbreviated as skew ch-G)-type transverse mode oscillation in a thin-slice solid-state laser with wide-aperture laser-diode pumping. The present hybrid skew-chG mode was proved to be formed by the locking of nearly frequency-degenerate TEM₀₀ and annular fields. The resultant modal-interference-induced gain modulation at the beat frequency between the two modal fields, which is far above the relaxation oscillation frequency, increased the experimental self-mixing modulation bandwidth accordingly. Fifty-fold phase amplification was achieved in a strong optical feedback regime. Full article

Finger vein recognition algorithms based on deep learning techniques are widely used in many fields. However, the training of finger vein recognition models is hindered by privacy issues and the scarcity of public datasets. Although applying federated learning techniques to finger vein recognition can effectively address privacy concerns, data heterogeneity across clients limits the performance of the models, especially on small datasets. To address these problems, in this paper, we propose a new federated finger vein recognition algorithm (FedPSFV). The algorithm is based on the federated learning framework, which increases the interclass distance of each dataset by sharing the prototypes among clients to solve the data heterogeneity problem. The algorithm also integrates and improves the margin-based loss function, which advances the feature differentiation ability of the model. Comparative experiments based on six public datasets (SDUMLA, MMCBNU, USM, UTFVP, VERA, and NUPT) show that FedPSFV has better accuracy and generalizability; the TAR@FAR = 0.01 is improved by 5.00–11.25%, and the EER is reduced by 81.48–90.22% compared to the existing methods. Full article

This paper presents the hydrological and meteorological parameters of the Wolfgang storm surge on the southern Baltic Sea coast and the storm’s impact on coastal areas with highly urbanised and developed zones. The surge emerged during a rare cyclonic system that was located over Western Europe in October 2023. A high difference in air pressure between the western and eastern parts of the Baltic coast led to the high-velocity wind blowing from the eastern direction to the centre of the cyclone located over Denmark. It caused high sea levels in the western part of the Baltic Sea. On the German and Danish coasts, the inflow of water at a high wind velocity perpendicular to the coast caused a very high surge of the sea and strong undulation. In this part of the Baltic Sea, the storm caused an increase in the sea level ranging from 1.5 to 2.2 m above average. It was lower on the eastern part of the Polish coast, exceeding 0.9 m above average sea level. The erosion of the base of cliffs ranged from 2 to 7 m, depending on the sea level. The dune erosion was larger but more varied, which resulted from different heights of the beach, at a maximum of up to 18 m. The water run-up reached 5.2 m above mean sea level (AMSL). The run-up parameter is a more accurate indicator of the potential threat than the sea level height. As a result of water run-up on the coast, lowlands situated even as far as 300 m from the shore were flooded. The storm caused significant damage to the coastal infrastructure and harbours. Research was conducted based on field studies and the analysis of digital documentation from websites, with the records of water run-up and the effects of the storm. Field studies were based on measures of coast retreat. Sea levels and wind were studied based on collected data. Full article

Actinomycetes are a representative group of bacteria that inhabit soil; in particular, Streptomyces coelicolor M511 produces actinorhodin and undecylprodiginine. Among them, undecylprodiginine has antibiotic and immunosuppression activity and is a secondary metabolite with high potential applications in biotechnological and pharmaceutical fields. High temperature stress (37 °C) reduced the biosynthesis of undecylprodiginine and induced specific branched chain alkylprodiginine derivatives, compared with the optimal growth temperature (30 °C). Also, the stress stimulated the synthesis of straight-chain FA for enhancing membrane rigidity. The inhibition of undecylprodiginine biosynthesis under high temperature stress seems to be induced by the heat sensitivity of the RedP enzyme, and this inhibition is compensated by FAS FabH. Since FabH, a homologue of RedP, has a broader substrate specificity, it leads to the production of methylundecylprodiginine and methyldodecylprodiginine. The external addition of isoleucine (as well as that of leucine and valine to a far lesser extent) enhances the synthesis of these derivatives since isoleucine catabolism generates precursors used for the biosynthesis of these compounds. These findings reveal temperature-dependent changes in precursor utilization and prodiginine diversity, providing insights into metabolic plasticity and strategies establishing a foundation for secondary metabolite derivatives engineering strategies through precursor supplementation or temperature regulation. Full article

LiDAR technology has undergone significant advancement in recent years, establishing itself as a technique for long-range, high-precision detection. As its use expands into more intricate scenarios, the need to overcome blind spots in the scanning field and enhance system stability has become increasingly critical. This paper introduces a novel coaxial LiDAR system featuring a double-clad optical fiber-based receiver which consists of a single-mode fiber core for the emission of the laser beam and a multimode inner cladding for the collection and transmission of the back-reflected beam. The real-time system is specifically engineered to measure distances in both near and far fields, eliminating blind spots. Experimental evaluations demonstrate that our system achieves a detection range of 0.2–70.7 m, with a distance accuracy of 3.4 cm and an angular resolution of 0.018°. Compared with conventional LiDAR systems, our approach eliminates the need for complex optical pathway designs and algorithmic compensation. It offers a simplified structure, enhanced stability, and high accuracy. Full article

The construction industry is critically reliant on efficient supply chains to ensure better project management, success, and profitability. This research examined the critical and ongoing challenges within the construction supply chain, with a particular emphasis on the persistent shortage of truck drivers and its far-reaching implications for construction logistics. Utilizing a structured multi-phase approach, the research integrated a comprehensive literature review, bibliometric analysis, and an empirical case study involving commercial motor vehicle (CMV) drivers. The literature review established the current state of knowledge on transportation labor shortages. At the same time, the bibliometric analysis revealed four key thematic clusters that collectively define the primary areas influencing construction supply chain performance. The case study reinforced these findings by highlighting key factors contributing to driver shortages, including demographic shifts, challenging working conditions, regulatory barriers, and geopolitical disruptions. The paper concludes with practical implications for industry practitioners, policymakers, and supply chain managers, emphasizing the necessity of integrative operational and strategic responses to build resilient and sustainable construction supply chains and logistics systems, with a specific focus on truck driver shortages. By examining both academic literature and field-based perspectives, this research provides a comprehensive understanding of how labor shortages, particularly in transportation, can destabilize construction supply chains and identifies the most effective measures to support their foundations. Full article

The characterization of lithology within Quaternary aquifers holds significant geological importance for the protection, management, and utilization of groundwater resources, yet it continues to present considerable challenges. Indicator Kriging (IK) is a non-parametric, probability-based method of spatial interpolation. It considers the correlation and variability between data points, and its popularity stems from its alignment with geological experts’ principles. However, it still encounters issues in complex geological conditions. To address the limited capacity of conventional IK in reproducing geological variables within heterogeneous geological settings, this study develops an ordered IK method incorporating field variogram function parameters. This framework dynamically extends IK applications by integrating stratigraphic extension trends, requiring experts to formalize spatial variation trends into geological knowledge data, subsequently transformed into constraint parameters for interpolation. Estimation paths are determined via Euclidean distances between points-to-be-estimated and valid data, executing ordered IK following near-to-far and bottom-to-top principles. Results directly depict QLS formation spatial distributions or undergo expert modification for quantitative analysis, demonstrating superior integration of geological knowledge compared to empirical variogram fitting and partitioned IK estimation. The method reduces deviation from expert-interpreted spatial distributions while maintaining computational efficiency and multi-factor integration, with three case analyses confirming enhanced accuracy in lithology distribution reproduction and improved geostructural congruence in complex geological reconstruction. This approach revitalizes Kriging applications in complex geological research, synergizing domain cognition with computational efficacy to advance precision in geological characterization and support government decision-making. Full article