Search Results (3,121)

This study investigates the macroeconomic and financial repercussions of a real estate bubble burst in South Korea through the application of Bayesian estimation and impulse response function analysis. By utilizing this approach tailored to the specific economic conditions of South Korea, the research effectively captures the complex ripple effects across a range of financial and macroeconomic variables. The results demonstrate that a real estate bubble burst markedly increases financial market risks, leading to heightened liquidity demands within the banking sector and necessitating adjustments in both deposit rates and bond yields. The study also emphasizes the differentiated impacts on patient and impatient households, where wealth losses drive significant shifts in consumption and labor supply behaviors, further constrained by prevailing labor market conditions. Additionally, the broader economic implications are examined, revealing the adverse effects on corporate output and investment, as well as the dynamics of international capital flows that impact foreign exchange reserves and exchange rates. These findings highlight the urgent need for proactive monitoring and policy interventions to mitigate the detrimental effects of real estate bubbles, ensuring financial stability and fostering sustainable economic growth in South Korea. Full article

The aim of this study was to evaluate whether a system involving ozonated water and ultrasound causes de-epithelization of the human amniotic membrane (HAM). The experiment protocol was carried out in four stages. Stage I was carried out to determine the duration of the experiment. Stage II comprised the first experiment, involving four groups of samples studied in triplicate: control/natural (IN), processed with ultrasound in a liquid medium (US), processed with ozonated water (O3), and processed with ozonated water combined with ultrasound (US_O3). Stage III was performed to confirm the results, following the same steps present in Stage II. Stage IV involved the use of oxygen to confirm the hypothesis. Histological analysis was carried out to verify whether the effects of O₂ were similar to those of O₃. The system was activated, and ozonation was carried out for 10 min, as in the previous experiment, reaching a concentration level of 3.0 mg/L. The samples were submerged and positioned in the reservoir and processed separately for 55 min. The biochemical properties were assessed using Fourier transform infrared spectroscopy, and the morphology was examined using histology and scanning electron microscopy. The spectra of the samples exhibited similarities; however, subtle changes were highlighted, such as smooth band shifts and intensity changes. The morphology indicated that ultrasound achieved more efficient HAM de-epithelialization compared to ultrasound combined with ozonated water and ozonated water alone. One plausible hypothesis for this observation is that cavitation represents the primary mechanism responsible for de-epithelialization. When ultrasound is combined with ozone, the bubbles generated by ozone gas reduce the cavitation effect. This study is pioneering as it demonstrates an ultrasound system capable of the efficient de-epithelialization of the HAM. Full article

In the digital age, personalized recommendation systems have become crucial for information dissemination and user experience. While traditional systems focus on accuracy, they often overlook diversity, novelty, and serendipity. This study introduces an innovative recommendation system model, Time-based Outlier Aware Recommender (TOAR), designed to address the challenges of content homogenization and information bubbles in personalized recommendations. TOAR integrates Neural Matrix Factorization (NeuMF), Bidirectional Long Short-Term Memory Networks (Bi-LSTM), and Mean Shift clustering to enhance recommendation accuracy, novelty, and diversity. The model analyzes temporal dynamics of user behavior and facilitates cross-domain knowledge exchange through feature sharing and transfer learning mechanisms. By incorporating an attention mechanism and unsupervised clustering, TOAR effectively captures important time-series information and ensures recommendation diversity. Experimental results on a news recommendation dataset demonstrate TOAR’s superior performance across multiple metrics, including AUC, precision, NDCG, and novelty, compared to traditional and deep learning-based recommendation models. This research provides a foundation for developing more intelligent and personalized recommendation services that balance accuracy with content diversity. Full article

Numerous studies have shown that explosive sequence loads can cause serious damage to underwater vehicles, especially the bubble surge in the later stage of the explosion, which poses a huge threat to the internal structure of the vehicle. This study explores the damage characteristics of cylindrical shell structures under complete sequence loads based on the Arbitrary Lagrangian–Eulerian (ALE) method. By conducting experiments on the surge characteristics near the damaged plate under explosive action and comparing them with numerical results, the effectiveness of the method is verified. Subsequently, the damage characteristics of single- and double-layered cylindrical shell structures under underwater explosion sequence loads (shock waves, bubbles, surges) were explored, and the failure modes of cylindrical shell structures under various loads were summarized. The results indicate that the damage of shock waves to single-layer cylindrical shell structures is most severe at a blast distance of 0.5 m. For double-layer cylindrical shells, increasing the blast distance will reduce the impact of bubble surge on the pressure-resistant shell. The stress and strain in the central area of the pressure-resistant shell also decrease, and the deflection and Z-direction velocity also decrease accordingly. This study laid the foundation for enhancing the impact resistance of underwater vehicles. Full article

Background: Telenursing could improve continuity of care in patients with cancer. This study aims to explore the expectations and perceptions of patients with lung cancer and melanoma toward telenursing. Methods: A descriptive qualitative study using a phenomenological approach was conducted on a convenience sampling of twenty patients aged 18 years or over from a Cancer Center. With the consent of patients and the relevant Ethics Committee, in-depth open-ended face-to-face interviews were conducted until data saturation. The phenomenon’s essence was achieved through themes emerging from the qualitative data analysis. Results: Patients’ perceptions and expectations were related to areas explored by a general theme on the nurse–patient relationship’s importance. Four themes and eleven sub-themes were focused on misconceptions about lack of use, patients’ potential and fears, the home as a place of care, and the caring relationship. Fifteen patients perceived the internet as a chaotic “bubble”. Conclusions: Despite the lack of previous use, patients consider telenursing positively as “a bridge between home and care”, especially in the advanced stages of the disease. They highlighted strengths and weaknesses of telenursing, such as having “someone for you”, connection, fear of psychological addiction, loss of privacy, and lack of empathy. This study was not registered. Full article

Helium ions implanted into metals can form ordered bubbles that are isomorphic to the host lattice. While long-range elastic interactions are generally believed to drive bubble superlattice formation, the interactions between individual helium solutes are not yet fully understood. Our first-principles calculations reveal that in molybdenum, Friedel oscillations induced by individual helium atoms generate potential barriers and wells that influence helium pairing and clustering at short He-He distances. These repulsive and attractive interactions at high concentrations provide thermodynamic driving forces that align randomly distributed helium atoms into Mo-He superlattices. Friedel oscillations may have broad impacts on solute–solute interactions in alloys. Full article

In view of the necessity of measuring the air content in oil in two-phase flows in the context of general industry, a review of the most popular methods of measuring the air content in oil was carried out. This review includes an assessment of their advantages and disadvantages and of whether they meet criteria such as the degree of filling, the size and number of bubbles, verification, the absence of additional pressure drops, simplicity, and repeatability. In the review, the following methods were examined: the classic trapping method, a modified trapping method, a trapping method using hydrostatic pressure loss, the pressure loss due to frictional flow resistance, the pressure loss with a rapid increase in diameter, the pressure drop in a Venturi tube, the pressure drop in an orifice, a method using the Coriolis effect, the electrical resistance method, the electrical conductivity method, the electromagnetic method, the electrical capacitance method, the thermal anemometry method, the liquid–solid contact electrification method, the photographic method, holography, light scattering, sound dispersion, the ultrasonic transit-time method, X-ray radiation, gamma radiation, neutron radiation, and fiber-optic methods. Full article

The existence of propane (C₃H₈) in a CO₂-oil mixture has great potential for increasing CO₂ solubility and decreasing minimum miscibility pressure (MMP). In this study, the enhanced solubility, reduced viscosity, and lowered MMP of CO₂-saturated crude oil in the presence of various amounts of C₃H₈ have been systematically examined at the reservoir conditions. Experimentally, a piston-equipped pressure/volume/temperature (PVT) cell is first validated by accurately reproducing the bubble-point pressures of the pure component of C₃H₈ at temperatures of 30, 40, and 50 °C with both continuous and stepwise depressurization methods. The validated cell is well utilized to measure the saturation pressures of the CO₂-C₃H₈-oil systems by identifying the turning point on a P-V diagram at a given temperature. Accordingly, the gas solubilities of a CO₂, C₃H₈, and CO₂-C₃H₈ mixture in crude oil at pressures up to 1600 psi and a temperature range of 25–50 °C are measured. In addition, the viscosity of gas-saturated crude oil in a single liquid phase is measured using an in-line viscometer, where the pressure is maintained to be higher than its saturation pressure. Theoretically, a modified Peng–Robinson equation of state (PR EOS) is utilized as the primary thermodynamic model in this work. The crude oil is characterized as both a single and multiple pseudo-component(s). An exponential distribution function, together with a logarithm-type lumping method, is applied to characterize the crude oil. Two linear binary interaction parameters (BIP) correlations have been developed for CO₂-oil binaries and C₃H₈-oil binaries to accurately reproduce the measured saturation pressures. Moreover, the MMPs of the CO₂-oil mixture in the presence and absence of C₃H₈ have been determined with the assistance of the tie-line method. It has been found that the developed mathematical model can accurately calculate the saturation pressures of C₃H₈ and/or CO₂-oil systems with an absolute average relative deviation (AARD) of 2.39% for 12 feed experiments. Compared to CO₂, it is demonstrated that C₃H₈ is more soluble in the crude oil at the given pressure and temperature. The viscosity of gas-saturated crude oil can decrease from 9.50 cP to 1.89 cP and the averaged MMP from 1490 psi to 1160 psi at 50 °C with the addition of an average 16.02 mol% C₃H₈ in the CO₂-oil mixture. Full article

A stable attachment between bubbles and solid particles is essential for flotation. Therefore, it is particularly necessary to study the dynamic process that occur in the attachment of bubbles to a solid surface. In this paper, Teflon and plexiglass plates were used as hydrophobic and hydrophilic solid surfaces, respectively, and solid surfaces with roughness of 0.018 μm to 5.33 μm were prepared by polishing with sandpaper. The influence of roughness on the dynamic process in bubble attachment to solid surfaces with different hydrophobicity was studied via a high-speed camera (750 frames per second). It was found that roughness played a positive role in the attachment to the hydrophobic Teflon surface while a negative role in the attachment to the hydrophilic plexiglass surface in terms of the bubble’s attachment to the solid plates. For a smooth Teflon surface, the formation of three–phase contact (i.e., the drainage of wetting film) took up to 95 ms, whereas for a very rough Teflon surface it took only 5 milliseconds. On the contrary, the high roughness prevented the bubble from attaching to the hydrophilic plexiglass surface. It was concluded that the increased roughness of Teflon plates was conductive to air entrapment in surface irregularities, inducing the rapid rupture of the wetting film on a very rough Teflon surface, while the increased roughness of the plexiglass plates resulted in “water pockets” in surface grooves, making the wetting film on the plexiglass surface stable. Full article

Micro- and nano-bubble jet stirring, as an emerging technology, shows great potential in complex mineral sorting. Flow field characteristics and structural parameters of the gas–liquid two-phase system can lead to uneven bubble distribution inside the reaction vessel. Gas–liquid mixing uniformity is crucial for evaluating stirring effects, as increasing the contact area enhances reaction efficiency. To improve flotation process efficiency and resource recovery, further investigation into flow field characteristics and structural optimization is necessary. The internal flow field of the jet-stirred tank was analyzed using computational fluid dynamics (CFDs) with the Eulerian multiphase flow model and the Renormalization Group (RNG) k − ε turbulence model. Various operating (feeding and aerating volumes) and structural parameters (nozzle direction, height, inner diameter, and radius ratio) were simulated. Dimensionless variance is a statistical metric used to assess gas–liquid mixing uniformity. The results indicated bubbles accumulated in the middle of the vessel, leading to uneven mixing. Lower velocities resulted in low gas volume fractions, while excessively high velocities increased differences between the center and near-wall regions. Optimal mixing uniformity was achieved with a circumferential nozzle direction, 80 mm height, 5.0 mm inner diameter, and 0.55 radius ratio. Full article

In order to study the feasibility of forming microtexture at the surface of 7050 aluminum alloy by laser-induced cavitation bubble, and how the density of microtexture influences its tribological properties, the evolution of the cavitation bubble was captured by a high-speed camera, and the underwater acoustic signal of evolution was collected by a fiber optic hydrophone system. This combined approach was used to study the effect of the cavitation bubble on 7050 aluminum alloy. The surface morphology of the microtexture was analyzed by a confocal microscope, and the tribological properties of the microtexture were analyzed by a friction testing machine. Then the feasibility of the preparation process was verified and the optimal density was obtained. The study shows that the microtexture on the surface of a sample is formed by the combined results of the plasma shock wave and the collapse shock wave. When the density of microtexture is less than or equal to 19.63%, the diameters of the micropits range from 478 μm to 578 μm, and the depths of the micropits range from 13.56 μm to 18.25 μm. This shows that the laser-induced cavitation bubble is able to form repeatable microtexture. The friction coefficient of the sample with microtexture is lower than that of the untextured sample, with an average friction coefficient of 0.16. This indicates that the microtexture formed by laser-induced cavitation bubble has a good lubrication effect. The sample with a density of 19.63% is uniform and smooth, having the minimum friction coefficient, with an average friction coefficient of 0.14. This paper provides a new approach for microtexture processing of metal materials. Full article

An equatorial plasma bubble (EPB) is characterized by ionospheric irregularities which disturb radio waves by causing phase and amplitude scintillations or even signal loss. It is becoming increasingly important in space weather to assure the reliability of radio systems in both space and on the ground. This paper presents a newly established GNSS ionospheric observation network (GION) around the north equatorial ionization anomaly (EIA) crest in south China, which has a longitudinal coverage of ∼30° from 94°E to 124°E. The measurement with signals from geostationary earth orbit (GEO) satellites of the BeiDou navigation satellite system (BDS) is capable of separating the temporal and spatial variations of the ionosphere. A temporal fluctuation of TEC (TFT) parameter is proposed to characterize EPBs. The longitude of the EPBs’ generation can be located with TFT variations in the time–longitude dimension. It is found that the post-sunset EPBs have a high degree of longitudinal variability. They generally show a quasiperiodic feature, indicating their association with atmospheric gravity wave activities. Wave-like structures with different scale sizes can co-exist in the same night. Full article

The whale optimization algorithm has several advantages, such as simple operation, few control parameters, and a strong ability to jump out of the local optimum, and has been used to solve various practical optimization problems. In order to improve its convergence speed and solution quality, a reinforced whale optimization algorithm (RWOA) was designed. Firstly, an opposition-based learning strategy is used to generate other optima based on the best optimal solution found during the algorithm’s iteration, which can increase the diversity of the optimal solution and accelerate the convergence speed. Secondly, a dynamic adaptive coefficient is introduced in the two stages of prey and bubble net, which can balance exploration and exploitation. Finally, a kind of individual information-reinforced mechanism is utilized during the encircling prey stage to improve the solution quality. The performance of the RWOA is validated using 23 benchmark test functions, 29 CEC-2017 test functions, and 12 CEC-2022 test functions. Experiment results demonstrate that the RWOA exhibits better convergence accuracy and algorithm stability than the WOA on 20 benchmark test functions, 21 CEC-2017 test functions, and 8 CEC-2022 test functions, separately. Wilcoxon’s rank sum test shows that there are significant statistical differences between the RWOA and other algorithms Full article

Launched on 22 November 2013, Swarm is the fourth in a series of pioneering Earth Explorer missions and also the European Space Agency’s (ESA’s) first constellation to advance our understanding of the Earth’s magnetic field and the near-Earth electromagnetic environment. Swarm provides an ideal platform in the topside ionosphere for observing ultra-low-frequency (ULF) waves, as well as equatorial spread-F (ESF) events or plasma bubbles, and, thus, offers an excellent opportunity for space weather studies. For this purpose, a specialized time–frequency analysis (TFA) toolbox has been developed for deriving continuous pulsations (Pc), namely Pc1 (0.2–5 Hz) and Pc3 (22–100 mHz), as well as ionospheric plasma irregularity distribution maps. In this methodological paper, we focus on the ULF pulsation and ESF activity observed by Swarm satellites during a time interval centered around the occurrence of the 24 August 2016 Central Italy M6 earthquake. Due to the Swarm orbit’s proximity to the earthquake epicenter, i.e., a few hours before the earthquake occurred, data from the mission may offer a variety of interesting observations around the time of the earthquake event. These observations could be associated with the occurrence of this geophysical event. Most notably, we observed an electron density perturbation occurring 6 h prior to the earthquake. This perturbation was detected when the satellites were flying above Italy. Full article

Given a graph $G=\left(V\right(G),V(E\left)\right)$, a non-negative integer g and a set of faulty vertices $F\subseteq V\left(G\right)$, the g-extra connectivity of G, denoted by ${\kappa }_g\left(G\right)$, is the smallest cardinality of F, whose value of deletion, if exists, will disconnect G and give each remaining component at least $g+1$ vertices. The g-extra diagnosability of the graph G, denoted by $t_g\left(G\right)$, is the maximum cardinality of the set F of fault vertices that the graph can guarantee to identify under the condition that each fault-free component has more than g vertices. In this paper, we determine that g-extra connectivity of $(n,k)$-bubble-sort network $B_{n,k}$ is ${\kappa }_g\left(B_{n,k}\right)=n+g(k-2)-1$ for $4\le k\le n-1$ and $0\le g\le n-k$. Afterwards, we show that g-extra diagnosability of $B_{n,k}$ under the PMC model $(4\le k\le n-1$ and $0\le g\le n-k)$ and MM* model $(4\le k\le n-1$ and $0\le g\le min\{n-k-1,k-2\})$ is $t_g\left(B_{n,k}\right)=n+g(k-1)-1$, respectively. Full article