Search Results (2,359)

This paper focuses on the issue of unmodeled dynamics and large-range parametric uncertainties in air-breathing hypersonic vehicles (AHV), proposing an adaptive dynamic surface control method based on radial basis function (RBF) neural networks. First, the hypersonic longitudinal model is transformed into a strict-feedback control system with model uncertainties. Then, based on backstepping control theory, adaptive dynamic surface controllers incorporating RBF neural networks are designed separately for the velocity and altitude channels. The proposed controller achieves three key functions: (1) preventing “differential explosion” through low-pass filter design; (2) approximating uncertain model components and unmodeled dynamics using RBF neural networks; (3) enabling real-time adjustment of controller parameters via adaptive methods to accomplish online estimation and compensation of system uncertainties. Finally, stability analysis proves that all closed-loop system signals are semi-globally uniformly bounded (SGUB), with tracking errors converging to an arbitrarily small residual set. The simulation results indicate that the proposed control method reduces steady-state error by approximately 20% compared to traditional controllers. Full article

Thorium-rare earth-iron oxide deposits of the Lemhi Pass district, Idaho and Montana, are enriched in the middle rare earth elements (REE), and particularly neodymium (Nd). Overall, thorium (Th) and total rare earth oxide (TREO) grades of the deposits are sub equal at 0.4 wt. % but locally exceed 1 wt. % TREO. Nd-monazite, the major REE phase (35 wt. % Nd₂O₃) occurs in hydrothermal Th-REE mineralized quartz veins and biotite-rich shear zones of enigmatic origin. Hosted in Mesoproterozoic metasedimentary rocks, the deposits are modest in size but present over a large area with no obvious source pluton exposed. This paper documents the geochemistry of the monazite and provides the first geochronological data to constrain its origin. Elemental mapping and U-Th-total Pb EPMA dating of the monazite and thorite document a Paleozoic age for mineralization centered in the Late Devonian at approximately 355 Ma ± 20 Ma. A second period of volumetrically minor Th and REE remobilization is dated as Mesozoic (ca. 100 Ma). For context, a reactivated passive continental margin was present during the Devonian in eastern Idaho, while the Mesozoic was a time of major accretionary tectonics and arc magmatism further west. Nd and Pb isotopic data require a significant interaction of the fluids with an ancient crustal component represented by regional Mesoproterozoic metasedimentary rocks and granitoids. A source–transport–deposition model is hypothesized with metasomatic fractionation and enrichment of Nd during regional hydrothermal circulation. The aqueous fluids were hot, oxidizing, and likely saline, but the exact source of the Th and REEs and the mechanism of enrichment remains problematic. Additional analytical work and increased knowledge of the regional and district geology will improve this unconventional hypothesis for formation of Lemhi Pass’ unusual Nd-rich Th-REE-Fe mineralization. Full article

HPAM-Cr³⁺ (partially hydrolyzed polyacrylamide-chromium ion) gels are widely used in enhancing oil recovery (EOR) due to their advantages of low cost, controllability, and high strength. The propagation distance of gels within the reservoir significantly negatively impacts their gelation performance. However, the extent of this influence remains unclear, hindering precise optimization for field applications. This study first established a gelation performance characterization method based on visual inspection, rheological parameters, and long-term stability, accurately classifying gels into five types: stable strong gel (SSG), stable weak gel (SWG), colloidal dispersion gel (CDG), unstable gel (USG), and over-crosslinked gel (OCG). Subsequently, cross-experiments were conducted using varying concentrations of HPAM and Cr³⁺. Based on the contour map of visual appearance, storage modulus (G′), and water loss rate (R_w) of the gels, distribution maps of gel morphology versus concentration were constructed. The gel performance was found to depend on the HPAM concentration and the crosslinking ratio (molar ratio of HPAM carboxyl groups to Cr³⁺ ions). No gel formation occurred when the HPAM concentration was below 800 mg/L, while concentrations above 2500 mg/L effectively inhibited over-crosslinking. The crosslinking ratio range for forming SSG was 5.56 to 18.68, with an optimal value of 9.27. Furthermore, the effect of propagation distance on gelation performance was investigated through 60 m sand-packed flow experiments. Results indicated that the minimum value of the crosslinking ratio was 2.632, the stable SSG formed when the propagation distance was less than 21 m, SWG formed within the 21–34 m range, and no intact gel formed beyond 34 m. It means that only the first 35% of the designed distance formed effective SSG for plugging. Finally, an optimization method for gel dosage design was established based on the findings. This method determines the optimal gel dosage for achieving effective plugging by calculating the volume of crosslinking system passing through the target fluid diversion interface and referencing the gel morphology distribution maps. These findings provide a straightforward and effective approach for the precise design of in-depth profile control agents. Full article

This work is devoted to the study of the effect of the oscillating Poiseuille flow on the diffraction of light passing through a nematic layer bounded by a submicron relief at one of the inner surfaces of the plane capillary. In experimental nematic liquid crystal (NLC) cells with a hybrid planar–homeotropic orientation, a photo-profiled PAZO polymer layer with a sinusoidal relief with a depth of 180 and 360 nm and a period of 2 μm was used as a diffraction grating. The experimentally obtained dependencies of the flow-induced changes in the intensity of polarized light at the main and the first diffraction maxima on the amplitude of the low-frequency oscillating pressure gradient applied to the NLC layer are presented. Processing of the obtained results indicates the possibility of modulating the intensity of diffracted polarized light transmitted through the NLC layer by up to 10% when applying an oscillating pressure difference of up to 700 Pa to the layer of corresponding experimental cells in the absence of an analyzer in the optical scheme. Possible mechanisms responsible for the modulation of optical radiation in the main and first diffraction maxima are discussed. The discussed principles of controlling diffracted electromagnetic radiation can be used to create optofluidic modulators operating in both the visible and THz ranges. Full article

The adherents of various religions have during times of prayer and worship oriented themselves toward a fixed, sacred direction or location. Since ancient times, followers of Judaism have turned in prayer to Jerusalem. Traditionally, Zoroastrians have prayed facing a source of light—typically the sun or a fire—representing divine truth and presence. By the second and third centuries of the common era, many Christian communities prayed facing the east when offering the Lord’s prayer and other supplications. Initially, Muḥammad and his followers prayed toward Jerusalem, called the “Qiblih” (a technical word first used in the Qur’án for the direction of ṣalát, the Islamic obligatory prayer), but near the midpoint of Muḥammad’s ministry, the Qiblih was changed to the Kaabah in Mecca. In the mid-nineteenth century, the Báb, founder of the Bábí religion, redefined the Qiblih as “Him Whom God shall make manifest,” a figure whose imminent appearance the Báb anticipated. Years later, Bahá’u’lláh, founder of the Bahá’í Faith, confirmed the Báb’s designation of the Qiblih and claimed to be the figure promised by the Báb—and, thus, the Qiblih. Since Bahá’u’lláh’s passing in 1892, Bahá’ís have regarded the Shrine of Bahá’u’lláh near ‘Akká as their Qiblih. This paper considers three issues related to the concept of the Qiblih. First, it briefly surveys the concept in Judaism, Zoroastrianism, Christianity, Islam, and other traditions. Second, it examines the significance and implications of the Qiblih in Bahá’í texts and their antecedents in Bábí texts. In this regard, it argues that in Bahá’í theology, the Qiblih symbolizes the role, station, and authority of the Manifestation of God, the figure who, in Bahá’í thought, serves as the intermediary between God and humanity from age to age. Moreover, Bahá’u’lláh’s designation of a new Qiblih signaled the independence of the Bahá’í religion. Third, this study explores how from a Bahá’í perspective, Quranic verses concerning the Qiblih may be viewed. These include how Muḥammad’s alteration of the Qiblih to the Kaabah reflected his authority as the Manifestation of God to change a prior law. Further, attention is given to Qur’án 2:143 (“And thus We have made you a middle community…”), which occurs in the midst of the only verses in the Qur’án that decree a change in the Qiblih. Whereas Quranic commentators and scholars of Islam, influenced by the doctrine of Islam’s finality, interpreted the word “middle” (vasaṭ) in this verse as meaning just, moderate, or exemplary, Bahá’u’lláh affirmed the word’s more basic meaning and regarded the Muslim community as a religious community between other communities that preceded it and that will come after it, thus anticipating the emergence of a new religious community, which could potentially have its own Qiblih. Full article

Cannabidiol (CBD), a phytocannabinoid with therapeutic potential for neurological and other conditions, faces significant challenges in bioavailability due to its low water solubility, high lipophilicity, and extensive first-pass metabolism. Researchers have developed advanced nanodelivery systems addressing these limitations to enhance CBD’s absorption, stability, and efficacy. This review provides not only a comprehensive summary of current nanotechnological delivery strategies for CBD, including nanoemulsions, liposomes, polymeric micelles, nanosuspensions, and cyclodextrin inclusion complexes, but also introduces a distinct comparative and integrative perspective. Unlike previous reviews, our work synthesizes preclinical and clinical evidence while highlighting the novel integration of nanotechnology with bioenhancers and personalized medicine approaches. We further emphasize the emerging concepts of hybrid and smart nanocarriers, which have not yet been systematically discussed, positioning them as next-generation solutions to overcome CBD’s bioavailability challenges and paving the way for precision therapeutics. Full article

This study analysed how tactical systems and match outcomes influence micro-level passing network metrics across playing positions in a professional football team competing in the Portuguese First Division during the 2020–2021 season. It examined how structural variation affects Degree Centrality, Degree Prestige, and Proximity Prestige across tactical systems (1-4-1-4-1, 1-4-3-3, 1-3-4-3) and outcomes (win, loss, draw) in different positions. Data from 28 league matches were used, with adjacency matrices constructed from teammate interactions. Players were grouped into six positions: goalkeepers, fullbacks, central defenders, central midfielders, wingers, and strikers. One-way ANOVA revealed significant differences (p < 0.05) across positions, tactical systems, and match outcomes. Central defenders consistently showed higher values of Degree Centrality and Degree Prestige across most systems and outcomes, highlighting their structural importance. In contrast, strikers and wingers displayed greater Proximity Prestige in the 1-4-3-3 and 1-3-4-3, reflecting their offensive positioning. Match outcome analysis indicated that wingers had significantly higher Degree Prestige in won matches compared to losses. Overall, results show that micro-level network metrics vary meaningfully by position and context, underscoring the importance of interpreting them cautiously. Despite the novelty of this study, focusing on the initial tactical systems without capturing within-match adjustments may condition the generality of the results. Coaches and practitioners should account for tactical and outcome-related variations when applying network analysis to optimise team dynamics. Full article

Background/Objectives: The aim of this study was to evaluate the possible effects of shock wave (SW) application for the noninvasive treatment of impacted ureteral stones on the pericalcular ureteral tissue in terms of changes in ureteral wall thickness. Methods: A total of 114 patients with impacted proximal ureteral stones underwent ESWL at our department. Patient- and stone-related parameters (size, density, and location); radiological parameters, including ureteral wall thickness (UWT); and degree of hydronephrosis were assessed on NCCT images before and shortly after the procedure. The possible effects of applying high-energy shock waves to the pericalcular ureteral tissue were evaluated according to changes in ureteral wall thickness. A comparative evaluation was conducted based on the number of sessions and the outcomes of SWL. Results: The mean value of UWT after the first session of stone management decreased significantly when compared to the mean pre-operative value (p < 0.005). This was also noted after the second treatment session, after which the mean UWT was significantly lower than the pre-operative value (p < 0.005). However, the difference in the mean UWT before and after three sessions of SWL was not significant (p = 0.104). A detailed evaluation of these values in all groups revealed that although the decrease in the mean UWT in cases with a successful outcome was significant (p < 0.005), the change in these values was not significant in cases for which the treatment was unsuccessful (partial disintegration of the stone or no disintegration at all) (p = 0.145). Conclusions: Application of SW in patients with impacted upper ureteral stones may not have a detrimental effect on the ureteral wall or compromise a secondary procedure if the stones are successfully disintegrated and passed after one or two sessions. However, in the case of resistant stones, an increased number of sessions and more SWs may induce such adverse effects, warranting further evaluation in future studies. Full article

This study presents the design and simulation of an integrated pathway to produce Biodimethyl ether (Bio-DME) from biomethane derived from Agave sisalana residues, focusing on the downstream sections such as: (i) steam reforming of biogas and water-gas shift to generate syngas and (ii) indirect methanol synthesis followed by methanol dehydration to Bio-DME, including separation and recycle steps. The modeled scope excludes the anaerobic digestion stage. Benchmarking against the literature was used to validate model fidelity. The simulation delivered a single-pass methanol conversion of 81.8%, a Bio-DME reactor conversion of 44.6 mol%, and a Bio-DME yield/selectivity of ≈99 mol%; product purities reached ≈99.99 mol% Bio-DME at the first distillation column and ≈99.9 mol% MeOH in the recycle, indicating efficient separation. Compared to the literature, Bio-DME conversion in this study is slightly below the reported values (0.446 vs. 0.499, Δ = 0.053), while yield is very close to literature (0.99 vs. 0.9979, Δ = 0.0079). Incomplete methanol conversion emerges as the primary optimization lever, pointing to adjustments in operating conditions (T, p), recycle/purge strategy, and H₂/CO control. Overall, the results confirm the technical feasibility of the simulated sections and support the development of a sisal-based, low-carbon Bio-DME route relevant to Northeast Brazil. Full article

A star tracker lens works in the environment with the temperatures ranging from −40 °C to 80 °C (a range of 120 °C), which makes athermalization a crucial step in the design. Traditional approaches could spend quite an amount of iterative process in between the optimization for nominal condition and athermalization. It is highly desired that the optimization can start with a thermally robust layout to improve the design efficiency. This study takes the star tracker lens module with seven elements as the base for investigating the possible layout variation on dioptric power distribution and thermo-optic coefficient $dn/dT$ of the material, which are the two major factors of the layout interacting with each other to influence the thermal stability of the overall lens module. All the possible layouts are optimized firstly for the nominal condition at T = 20 °C, and only those meeting the optical performance specifications are selected for thermal performance evaluation. A merit function based on a thin lens model which represents the focal plane drift over a temperature range of 120 °C is then used as the criteria for ranking the layout variations passing the first stage. The layouts at top ranking exhibiting low focal plane drift become potential candidates as the final solution. The proposed methodology provides an efficient approach for designing thermally resilient star tracker optics, especially addressing the harsh thermal conditions encountered in Low Earth Orbit missions. Full article

Traditionally used to combat infections, systemic effects of antibiotics are increasingly recognized in the context of absorption through unconventional routes. One such as the ocular surface. This review tackles the bidirectional liver–eye axis, highlighting how trace antibiotic residues from environmental and therapeutic sources affect the tear film, disturb ocular microbiota, and impact liver metabolism. It engages in anatomical pathways, microbial regulation, pharmacokinetics, and systemic immune responses. Additionally, this review discusses forensic uses and new therapeutic strategies, stressing the importance of integrated environmental monitoring and precision medicine to tackle nonmedicinal antibiotic exposure. Due to the absence of results from a systematic literature review, a narrative literature review was undertaken instead. More than 100 studies discussing mechanistic, clinical, and experimental insights were reviewed, with 98 of those studies being documented as source literature. The findings demonstrate that antibiotics may penetrate and be absorbed through the ocular surface, cause modifications of the hepatic first-pass metabolism, and change the activity of cytochrome P450. Correlations were documented between the various liver function biomarkers and the ocular tear film, as well as the thickness of the retinal pigment epithelium. The dysbiosis of eye microbiota may be an indicator of systemic inflammation associated with immune dysregulation. Restoring microbial homeostasis and addressing systemic dysregulation are novel therapeutic approaches, including the use of probiotics, nanoparticle scavengers, and CRISPR. The eye is a sensory organ and a metabolically active organ. Systemically, the eye can affect the liver through the ocular surface and the antibiotics through the liver–eye axis. To protect the systemic health of the individual and the lensed metabolically active eye, the eye and liver must be viewed as a sentinel of systemic balance. Novel therapies will be necessary with the added need for environmental monitoring. Full article

Graft copolymers of polysaccharides with side chains of carbon-chain monomers have significant potential for a variety of practical applications. In this work, the effect of the N,N-methylenebisacrylamide (MBA) introduction stage and acrylamide concentration in microwave-assisted radical copolymerization with xanthan gum on the structure and sorption properties of the cross-linked graft copolymer was studied. It has been found that the spatial network density and average molecular weight of interstitial fragments can be controlled by varying these factors. Moderate crystallinity (<50%) and a highly developed surface of our synthesized samples were revealed using XRD and SEM. The graft copolymer exhibits the Schroeder effect; its liquid water sorption obeys Fick’s law and increases with MBA introduction at later stages and with increasing grafting degree, reaching 17.2 g/g. Studying the methylene blue sorption kinetics using pseudo-first/pseudo-second order models, a combined model and an average pseudo-order model have shown that the lower the monomer concentration in the reaction mixture and the earlier (from the onset of the reaction) the cross-linking agent is introduced, the higher the equilibrium sorption. The observed “equilibrium degree of sorption on xanthan gum vs. pseudo-order” relationship, which passes through a minimum, is explained by chemisorption and the sorbate consumption effect. An assumption is made about the prospects of using our synthesized copolymers for designing selective sorbents and ion-exchange membranes. Full article

Building clustering is a key challenge in cartographic generalization, where the goal is to group spatially related buildings into semantically coherent clusters while preserving the true distribution patterns of urban structures. Existing methods often rely on either spatial distance or building feature similarity alone, leading to clusters that sacrifice either accuracy or spatial continuity. Moreover, most deep learning-based approaches, including graph attention networks (GATs), fail to explicitly incorporate spatial distance constraints and typically restrict message passing to first-order neighborhoods, limiting their ability to capture long-range structural dependencies. To address these issues, this paper proposes LA-GATs, a multi-feature constrained and spatially adaptive building clustering network. First, a Delaunay triangulation is constructed based on nearest-neighbor distances to represent spatial topology, and a heterogeneous feature matrix is built by integrating architectural spatial features, including compactness, orientation, color, and height. Then, a spatial distance-constrained attention mechanism is designed, where attention weights are adjusted using a distance decay function to enhance local spatial correlation. A second-order neighborhood aggregation strategy is further introduced to extend message propagation and mitigate the impact of triangulation errors. Finally, spectral clustering is performed on the learned similarity matrix. Comprehensive experimental validation on real-world datasets from Xi’an and Beijing, showing that LA-GATs outperforms existing clustering methods in both compactness, silhouette coefficient and adjusted rand index, with up to about 21% improvement in residential clustering accuracy. Full article

The family dog is a valid model for studying complex human functions and psychological disorders such as Attention-Deficit/Hyperactivity Disorder (ADHD). Based on prior human research indicating impairments in cognitive flexibility related to ADHD, this study investigates the association between dogs’ ADHD-like traits and reversal learning performance. Since sleep improves learning both in humans and dogs, we also examined its impact in this context. Family dogs (N = 64) completed a two-way choice spatial reversal learning task, followed by a one-hour non-invasive sleep electroencephalography (EEG), and then a second reversal task. We used a validated human analogue questionnaire to assess ADHD. Dogs with higher ADHD scores required more trials to pass the first reversal test, but not after sleep. Electrode application was slower and sleep measurement more likely to fail in dogs with higher ADHD scores. Performance improved more from pre- to post-sleep in high-ADHD dogs if they spent at least 40% of the recording asleep. Our findings align with the human literature showing associations between ADHD and cognitive flexibility in dogs. The main novelty here is the ADHD-related potential benefits of repeated task exposure after sufficient sleep on cognitive flexibility. Cognitive training offers a promising direction to mitigate ADHD-related impairments in dogs. Full article

Biodegradable zinc-based alloys have recently emerged as promising candidates for temporary biomedical implants due to their favorable biocompatibility, appropriate degradation rate, and relatively simple processing. In this study, the Zn-0.1Mg alloy was investigated after being processed by means of a two-step equal-channel angular pressing (ECAP) route, consisting of the first pass at 150 °C followed by a second pass at room temperature. The mechanical properties were evaluated using uniaxial tensile tests at different strain rates, while the microstructure and phase composition were analyzed using synchrotron hard X-ray diffraction and transmission electron microscopy (TEM). The processed alloy exhibited a remarkable enhancement in both strength and ductility compared to the annealed state. At the lowest applied strain rate, a fracture elongation of up to 240% was achieved at room temperature, representing a unique manifestation of superplasticity under ambient conditions. Diffraction analysis confirmed the stability of the supersaturated Zn matrix with minor Mg₂Zn₁₁ intermetallic phase. TEM observations revealed an ultrafine-grained microstructure and activation of non-basal slip systems, which enabled efficient plastic flow. These findings demonstrate that controlled severe plastic deformation provides an effective pathway for tailoring Zn-Mg alloys, opening opportunities for their use in the next generation of bioresorbable low-to-moderate load orthopedic fixation devices, e.g., plates, screws, suture anchors and craniofacial miniplates. Full article