Search Results (1,166)

This manuscript presents a comprehensive Lie symmetry analysis of the KdV-Burgers equation, a prototypical model for nonlinear wave dynamics incorporating dissipation and dispersion. We systematically derive its six-dimensional Lie algebra and construct an optimal system of one-dimensional subalgebras. This framework is used to perform a symmetry reduction, transforming the governing partial differential equation into a set of ordinary differential equations. A key contribution of this work is the identification and analysis of several non-trivial invariant solutions, including a new Galilean-boost-invariant solution related to an accelerating reference frame, which extends beyond standard traveling waves. Through a detailed physical interpretation supported by phase plane analysis and asymptotic methods, we elucidate how the mathematical symmetries directly manifest as fundamental physical behaviors. This reveals a clear classification of distinct wave regimes—from monotonic and oscillatory shocks to solitary wave trains governed by the interplay between nonlinearity, dissipation and dispersion. The numerical validation verify the accuracy and physical relevance of the derived invariant solutions, with errors less than $0.5\%$ in the Burgers limit and $3.2\%$ in the weak dissipation regime. Our work establishes a direct link between the model’s symmetry structure and its observable dynamics, providing a unified framework validated both analytically and through the examination of universal scaling laws. The results offer profound insights applicable to fields ranging from plasma physics and hydrodynamics to nonlinear acoustics. Full article

Primordial germ cells (PGCs) are the unipotent precursors of sperm and ova, responsible for transmitting hereditary information across generations. Their ability to be isolated and cultured in vitro has opened new horizons for avian biotechnology, species conservation, and fundamental developmental research. In birds, the unique migratory pattern of PGCs—originating in the epiblast and traveling via the bloodstream to the gonads—enables their collection and manipulation during embryogenesis. Long-term in vitro culture systems have been successfully established in chickens, where defined media allow for stable proliferation and genetic modification. Applications include germline chimeras, generation of transgenic lines, recombinant protein production, and cryobanking of genetic resources. However, translating these advances to other species remains challenging due to interspecies variability in signaling requirements. Recent work in geese, ducks, quails, and zebra finches underscores the need for tailored media formulations and a better understanding of molecular regulation. This review summarizes established techniques, highlights key interspecies differences, and outlines future directions for the standardization and expansion of avian PGC culture systems to support conservation and biotechnology. Full article

The penetration rate of battery electric buses (BEBs) continues to rise, and the design of BEB networks has become the foundation for establishing efficient and sustainable public transportation systems. Improving the equity of bus network and reducing the total cost of the bus system are taken as the targets, a multi-objective programming model for TNDP is proposed in this study. Among them, the Gini coefficient of bus travel times during peak hours and the direct travel proportion of the elderly during non-peak hours are used to describe the equity of the bus network. When calculating the comprehensive cost, factors such as the fleet size of battery electric buses, charging facilities requirements, and charging costs are taken into account. To enhance the reliability of the obtained results, the Non-Dominated Sorting Genetic Algorithm II (NSGA-II) is adopted to generate the Pareto-optimal solution set. The Mandl’s benchmark network is used for comparative validation, and a case study based on the road network of Zhengzhou is undertaken. Calculation results indicate that the proposed model not only minimizes the total travel costs but also significantly reduces the Gini coefficient of the transportation mode distribution. Under the constraint of overall expenses, it effectively improves the equity and the direct travel proportion of the elderly served by the bus system. The results can provide quantitative support to formulate livelihood transportation policies for local government and optimize the allocation of public transportation resources. Full article

Policies rarely act on simple circles around project sites. We develop a policy-semantics-to-geometry workflow that converts clause-level rules in ordinances into auditable Policy Spatial Footprints (PSFs) with explicit boundaries, timing markers, and intensity tiers, and we measure exposure in network time on road–rail graphs. Using 1.10 million arm’s-length parcel transactions from five Yangtze River Delta cities (2012–2024) and a catalog of 64 policies across regulatory, transport, and industrial/functional families, we estimate dynamic capitalization under staggered roll-outs while separating direct footprint effects from adjacency diffusion. Direct exposures are associated with policy-relevant uplifts that build over several years and then stabilize; spillovers attenuate within a few minutes of network travel time. Effects are systematically larger in thicker markets and where pre-policy regulatory headroom is greater. The PSF framework yields estimator-consistent maps with provenance and uncertainty tiers, providing a transparent basis for land-value-capture scheduling and equity-aware carve-outs. Full article

A vast number of boreholes in underground mining operations are often plagued by deviation issues, which severely impact both production efficiency and safety. The accurate and rapid acquisition of borehole trajectories is fundamental for subsequent deviation control and correction. However, existing inclinometers are limited by their operational efficiency and estimation accuracy, making them inadequate for large-scale measurement demands. To address this, this paper proposes a novel method for the rapid and accurate reconstruction of underground mine borehole trajectories using a robotic system. We employ a custom-designed robot equipped with an Inertial Measurement Unit (IMU) and a displacement sensor, which travels stably while collecting real-time attitude and depth information. Algorithmically, a complementary filter is used to fuse data from the gyroscope with that from the accelerometer and magnetometer, overcoming both integration drift and environmental disturbances. A cubic spline interpolation algorithm is then utilized to time-register the low-sampling-rate displacement data with the high-frequency attitude data, creating a time-synchronized sequence of ‘attitude–displacement increment’ pairs. Finally, the 3D borehole trajectory is accurately reconstructed by mapping the attitude quaternions to direction vectors and recursively accumulating the displacement increments. Comparative experiments demonstrate that the proposed method significantly improves efficiency. On a complex trajectory, the maximum and mean errors were reduced to 0.38 m and 0.18 m, respectively. This level of accuracy is far superior to that of the conventional static point-by-point measurement mode and effectively suppresses the accumulation of dynamic errors. This work provides a new solution for routine borehole trajectory surveying in mining operations. Full article

The estimated increase in urban solid waste generation in the near future worldwide may negatively impact the environment and public health, and produce a significant economic impact on solid waste management. Recycling is crucial in mitigating this solid waste generation growth by diverting materials from landfills, reducing greenhouse gas emissions and pollution, conserving resources, and extending end-of-life strategies. In this study, we address the bin location–allocation problem for the collection of recyclable household waste, a key challenge in the context of the circular economy and efforts to mitigate the sustained growth of household waste generation. To tackle this problem, this study generalizes a previous mixed-integer linear programming (MILP) model to address different types of waste, particularly recyclable household waste, while minimizing total bin costs and ensuring that each generation point is assigned to the nearest collection site within a given threshold travel distance. Additionally, the model compares single and multi-stream collection strategies. For each case, we evaluate the options of locating recycling bins at road intersections and in open public spaces. Real-world data from the commune of Quinta Normal in Santiago, Chile is used to test our approach. This study also reports results of a sensitivity analysis of key parameters, including the generated household recyclable waste and the maximum distances users are willing to travel to dispose of their recyclable waste. Finally, managerial implications that emerge from this study are discussed, which may help authorities improve recyclable household waste collection, and outline future research directions. Full article

Background: This paper aims to provide an overview of corneal birefringence (CB), systematize the knowledge and current understanding of CB, and identify difficulties associated with introducing CB into mainstream clinical practice. Methods: Literature reviews were conducted, seeking articles focused on CB published between the early 19th century and the present time. Secondary-level searches were made examining relevant publications referred to in primary-level publications, ranging back to the early 17th century. The key search words were “corneal birefringence” and “non-invasive measurements”. Results: CB was first recorded by Brewster in 1815. Orthogonally polarized rays travel at different speeds through the cornea, creating a slow axis and a fast axis. The slow axis aligns with the pattern of most corneal stromal collagen fibrils. In vivo, it is oriented along the superior temporal–inferior nasal direction at an angle of about 25° (with an approximate range of −54° to 90°) from the horizontal. CB has been reported to (i) influence the estimation of retinal nerve fiber layer thickness; (ii) be affected by corneal interventions; (iii) be altered in keratoconus; (iv) vary along the depth of the cornea; and (v) be affected by intra-ocular pressure. Conclusions: Under precisely controlled conditions, capturing the CB pattern is the first step in a non-destructive process used to model the ultra-fine structure of the individual cornea, and changes thereof, in vivo. Full article

Low-thrust orbit transfer problems are central to reducing mission costs and enabling cleaner, more efficient space travel. However, they remain difficult to solve using mathematically superior indirect methods of optimization. This is mainly due to the sensitivity to initial guesses and ill-conditioned matrices generated using traditional indirect methods. This paper applies the Uniform Trigonometrization Method (UTM), a cutting-edge indirect optimization technique, to four cases of low-thrust low Earth orbit (LEO)-to-geostationary Earth orbit (GEO) transfer problems. Using the UTM framework, including efficient numerical continuation and problem scaling strategies, smoother optimal control solutions were obtained. The convergence of standard boundary value problem solvers, like MATLAB’s bvp4c, significantly increases while using the simplicity and efficiency of the UTM. The UTM was able to solve Case 1 in a simpler manner compared to the traditional indirect method presented in the literature. In Case 2, the UTM found results for a constant thrust value of 1 N, while a direct pseudospectral method failed to converge. The results obtained using the UTM for Case 2 have 20 times longer flight duration and revolutions of spacecraft around the Earth. The UTM efficiently performs trade studies using a continuation approach that generates additional insights into all cases of this problem. In Case 4, the UTM was able to easily generate a bang–bang control structure, which traditionally requires solving a complex multi-point boundary value problem. The results generated using the UTM are very high-resolution, as it relies on the necessary conditions of optimality and guarantees locally optimal solutions. These findings position the UTM as a promising indirect approach for solving real-world long-duration orbit transfers. Full article

Food and agricultural products shape tourism by linking communities and regions to leisure travel. Consumers’ perceptions of a country and its food products can shape their attitudes and behaviors toward it as a travel destination. This study compares the effects of general country image (GCI), product–country image (PCI), and product image (PI) on Chinese dairy consumers’ engagement with the country of origin as a travel destination (TDE). It also tests whether TDE mediates the effects of country images on consumer-based brand equity (BEQ) for dairy products. We analyzed 573 valid online responses from mainland China, a major market for dairy products and outbound tourism, using covariance-based structural equation modeling (CB-SEM) in AMOS 31. The results identify TDE as a key factor that fully mediates the effect of GCI on BEQ. PCI and PI show both direct effects on BEQ and indirect effects through TDE. The proposed framework links country evaluations to destination engagement and brand outcomes, highlighting opportunities for integrated cross-sector promotion. This research is among the first to examine co-marketing between the tourism sector and the dairy industry through a country-image perspective. It provides practical guidance for cross-sector strategy and contributes to ongoing debates in both fields. Full article

Climate change is one of the most pressing global environmental challenges, driven by the accumulation of greenhouse gases in the atmosphere. Industrial processes, particularly plastic injection molding, are major contributors due to their high energy demand, raw material use, and waste generation. This study quantifies the carbon footprint of plastic injection molding operations and identifies emission hotspots to support alignment with sustainability objectives. A greenhouse gas inventory was developed for the production processes of Petka Mold Industry in Adana, Türkiye, covering 1 January–31 December 2023. The assessment followed the ISO 14064-1:2019 standard and included emissions from direct fuel consumption, purchased electricity, refrigerant leaks, company vehicles, employee commuting, business travel, purchased goods, and waste transportation. Carbon dioxide, methane, and nitrous oxide were calculated in carbon dioxide equivalent units. This research represents the first comprehensive carbon footprint study in the plastic mold sector integrating all categories (Categories 1–6). In addition, uncertainty and materiality analyses were applied to ensure robustness and transparency, an approach rarely adopted in similar industrial contexts. While most previous studies are limited to Categories 1–3, this work expands the boundaries to all categories, offering a pioneering model for industrial applications. The total corporate GHG emissions for 2023 were calculated as 3922.75 metric tons of CO₂e. Among the categories, purchased raw materials and end-of-life product stages were the most significant contributors, whereas transport and auxiliary services had smaller shares. The results provide a reliable baseline for developing action plans and pursuing emission reduction targets. By combining full category coverage with rigorous assessment tools, this study contributes methodological novelty to corporate carbon accounting and establishes a foundation for future progress toward carbon neutrality. Full article

Background: Direct clinical training on real patients is essential in dental education. However, the declining patient inflow increasingly challenges this objective. This cross-sectional study aimed to assess patients’ experiences and preferences to derive recommendations for improving patient recruitment. Material and Methods: Over a period of one year, patients treated by students in the courses and final examinations at the dental school of conservative dentistry were questioned using a specially designed questionnaire and reviewed using their medical records. They were asked about their complete treatment process, and patient files were used to record socio-demographic as well as economic and appointment-specific data. Results: We analysed 297 patients (142 women, 47.8%; 155 men, 52.2%) treated by undergraduates across two semesters (four courses) and two final examinations. Median age was 57.0 years (IQR 46–67; mean 55.2, SD 15.2; range 14–85) with no sex-based difference (p > 0.05). Arrival was predominantly by car (72.7%, n = 216); median one-way distance was 20.5 km (IQR 11.2–32.1); and 58.4% were employed, while 41.6% were not employed (33.7% retired, 7.9% unemployed). The leading reason for course attendance was “satisfaction with previous treatments” (65.32%). Information sources were reported by 290/297 (98%); the most common was already being a course patient (143, 48.1%). Most patients attended one appointment (109, 36.7%). Median travel cost per appointment (including parking) was €17.0 (typically €10.0–€23.5). Of 285 respondents, 93.68% answered “Yes” to satisfaction with student treatment. Conclusions: Important steps include enhancing parking facilities, optimizing recall systems and appointment accessibility, and strengthening relationships with regular patients to encourage word-of-mouth referrals. The main focus is to maintain high clinical quality, ensure affordability, and further reduce patient copayments where possible. Full article

Reintroduction efforts of wildlife species seek to re-establish self-sustaining populations of targeted species within their historical ranges. Our study focuses on the Indian Grey Hornbill, which faced local extinction in the Gir National Park and Sanctuary, Gujarat, India. The last recorded direct sighting of the Indian Grey Hornbill in the study area dates back to the 1930s. Its presence gradually declined, leading to its eventual extinction in the region between 1950 and 1960. Since the declaration of Gir Forest as a sanctuary in 1965 and subsequently as a national park in 1975, habitat conditions have significantly improved. This positive trend created an opportunity for the reintroduction of the hornbills to establish a self-sustaining population. The reintroduction was conducted in two phases. During the first phase, twenty-eight birds were captured from known hornbill ranges within Gujarat, and five of them were equipped with PTT/GSM satellite transmitters. And in the second phase, twelve birds were captured, and six of them were fitted with PTTs to study their ranging patterns, habitat associations, and potential breeding activities. During the establishment or initial phase of reintroduction, the birds exhibited exploratory behaviour, resulting in larger home ranges (mean ± Standard Deviation, SD) (60.87 ± 68.51 km²), which gradually reduced to smaller home ranges (5.73 ± 10.50 km²) during later stages. Similarly, the daily and monthly distances travelled by the birds were significantly greater in the initial phase than in the later one. Nest site selection correlated significantly with girth at breast height (GBH) and tall trees. Our study provides essential information for hornbill reintroduction in the Gir landscape, aiding future conservation efforts for Indian Grey Hornbills. Full article

Unmanned aircraft are increasingly recognized for their potential to enhance healthcare logistics, offering rapid and reliable transport solutions. Among the many envisioned use cases, emergency medical deliveries stand out as particularly promising due to their immediate societal value. This study investigates the potential of drones operating under U-space to support hospital-to-hospital emergency deliveries in Madrid. Using the GEMMA tool, we modeled and simulated operations with two drone types along direct routes between four hospitals, resulting in six hospital pairs. Drone travel times were estimated and compared against road transport times obtained from the Google Routes API, incorporating one week of traffic data to capture daily and weekend variability. The results show substantial advantages of aerial transport, with time savings ranging from 2 to 26 min, equivalent to 35–58% compared to road transport. Drones consistently ensured deliveries within 15 min, outperforming regular cars (39%) and ambulances or motorcycles in highly congested periods. Sensitivity analysis confirms their reliability in scenarios with strict time constraints, especially under 15 min. These findings demonstrate that drones reduce travel times and improve predictability, providing a robust evidence base for policymakers and regulators to advance U-space integration in healthcare logistics. Full article

Wire Arc Additive Manufacturing (WAAM) has been recognized as an efficient and cost-effective metal additive manufacturing technique due to its high deposition rate and scalability for large components. However, the quality and repeatability of WAAM parts are highly sensitive to process parameters such as arc voltage, current, wire feed rate, and torch travel speed, requiring advanced monitoring and adaptive control strategies. In this study, a vision-based monitoring system integrated with a reinforcement learning framework was developed to enable intelligent in situ control of WAAM. A custom optical assembly employing mirrors and a bandpass filter allowed simultaneous top and side views of the melt pool, enabling real-time measurement of layer height and width. These geometric features provide feedback to a tabular Q-learning algorithm, which adaptively adjusts voltage and wire feed rate through direct hardware-level control of stepper motors. Experimental validation across multiple builds with varying initial conditions demonstrated that the RL controller stabilized layer geometry, autonomously recovered from process disturbances, and maintained bounded oscillations around target values. While systematic offsets between digital measurements and physical dimensions highlight calibration challenges inherent to vision-based systems, the controller consistently prevented uncontrolled drift and corrected large deviations in deposition quality. The computational efficiency of tabular Q-learning enabled real-time operation on standard hardware without specialized equipment, demonstrating an accessible approach to intelligent process control. These results establish the feasibility of reinforcement learning as a robust, data-efficient control technique for WAAM, capable of real-time adaptation with minimal prior process knowledge. With improved calibration methods and expanded multi-physics sensing, this framework can advance toward precise geometric accuracy and support broader adoption of machine learning-based process monitoring and control in metal additive manufacturing. Full article

Detailed studies were conducted on the photooxidation of salicylic acid (SA) in the presence of sodium hypochlorite (NaOCl), which is important in the context of water disinfection processes. It was shown that NaOCl alone causes slow degradation of SA (<10% after 60 min), while its combination with UV radiation significantly increases the efficiency of the process, especially at pH 7.5–10 (up to 30% degradation in 60 min). Eleven chlorinated transformation products have been identified, including 2,6-dichlorophenol and 2,4,6-trichlorophenol, which are characterized by high environmental persistence (>96 days) and the ability to travel distances exceeding 4000 km. QSAR analyses and ecotoxicological tests (Microtox^®, Daphtoxkit F^®, Lemna sp.) confirmed the significant toxicity of some compounds to fish, daphnia, and algae. It was found that the post-reaction mixture after the NaOCl/UV process exhibits higher toxicity than SA photolysis alone, indicating a significant contribution of chlorinated intermediates to environmental risk. The results highlight the need to develop alternative methods for removing pharmaceuticals that minimize the formation of persistent and toxic by-products, and indicate directions for further research on their monitoring in the aquatic environment. Full article