Spreading Characteristics Research Articles

Statistical Characteristics of Spread F in the Northeastern Edge of the Qinghai-Tibet Plateau during 2017–2022

Spread F (SF) in the ionosphere can be observed frequently in mid-latitude regions. It is suggested that atmospheric gravity waves play a significant role for the seeding of mid-latitude SF. Previous research suggested that the source of travelling ionospheric disturbances (TIDs) over China is in the southeastern and northeastern edge of the Qinghai-Tibet Plateau, however, until now there have been no ground-based observations of the ionosphere in this region. Recently, an advanced digital ionosonde was installed at Zhangye station (39.2°N, 100.54°E, Dip Lat 29.6°N) in the northeastern edge of the Qinghai-Tibet Plateau. It is an opportunity to verify the effect of gravity waves on the formation of mid-latitude SF by comparing it with observations in other regions of the Chinese sector. In this study, statistical analysis of SF recorded at Zhangye station during 2017–2022 was carried out. Results show that diurnal, seasonal and solar cycle characteristics of the occurrence rate of SF are similar with previous studies. At Zhangye station, the maximum occurrence rate of SF is during the post-midnight period in summer and winter. The occurrence rate of SF events have a negative relationship with solar activity. There is no obvious relationship between the occurrence rate of SF and geomagnetic activity. Comparing observations of other stations in the mid-latitude region, we found that the occurrence rates of SF (the annual maximum rates are from 33.83% to 53.29%) are much higher at Zhangye station. Further studies show that ionospheric disturbances can be observed frequently at Zhangye station, especially in autumn and winter. Gravity waves/TIDs in the northeast of the Qinghai-Tibet Plateau are suggested to explain the abnormal higher occurrence rate of SF at Zhangye station.

Identification and Reduction of Bitter Taste Determinant Compounds in Chocolate Spread Formulated with Candlenut

Candlenuts can be used as a substitute in producing chocolate spread due to their high-fat content. However, the limitation of using candlenut in the spread formulation is the existence of a bitter taste. This study aimed to investigate the effect of sodium bisulfite and sodium bicarbonate soaking treatment (100, 300, and 500 ppm) on reducing the bitter taste of candlenut seed. In order to reach the goal, bitter compounds of candlenut and chocolate spread were identified using Liquid chromatography-mass spectrometry (LC-MS). The sensory characteristics of chocolate spread were profiled using the Rate All That Apply (RATA) descriptive method. It was shown that the panelists identified 14 sensory attributes in the samples, one of which was bitter taste. Treatment with sodium bisulfite, as well as sodium bicarbonate at the level of 300 ppm, reduced the intensity of the bitter taste. The treatment reduced flavonoid and tannin levels by 85.21% and 82.08% in candlenut seeds. It also reduced flavonoid and tannin levels by 88.47% and 72.71% in chocolate spread, respectively. LC-MS identified 13 compounds that cause the bitter taste, namely quercetin, oleuropein, kaemferol, resveratrol dimer, luteolin, epicatechin, theobromine, caffeine, iso-humolones, colaflavone, chlorogenic acid, feruloyl-caffeoylquinic acid, and coumaroylquinic acid. This study creates a new technique for producing chocolate spread formulated with candlenuts with lower bitterness levels.

Numerical MCRT Simulation and Inter-Symbol Interference Analysis of Laser Multipath Transmission in Airborne Air-to-Air Channels

To address the issues of signal waveform distortion and inter-symbol interference, both of which lead to performance degradation in airborne laser communication due to multipath transmission in airborne air-to-air channels, theoretical analysis and Monte Carlo ray tracing (MCRT) simulation methods were employed. Based on airborne application conditions, this research conducted numerical simulations of the Gaussian beam multipath transmission in an air-to-air channel, with a focus on analyzing the impact of meteorological conditions, communication distance, transmitter power, and initial pulse width on the pulse time spreading characteristics of received optical signals. In addition, an analysis of these parameters’ impact on the inter-symbol interference (ISI) and bit error rate (BER) was conducted. The research findings can serve as a reference for the design of anti-interference techniques in airborne laser communication links.

Spatial Patterns and the Evolution of Logistics Service Node Facilities in Large Cities—A Case from Wuhan

Logistics services are integral to urban economic activity, and delving into the spatial distribution traits and evolutionary pathways of various kinds of logistics service node facilities (LSNF) is markedly valuable for understanding a city’s functional spatial makeup and refining the spatial layout of logistics services. This study quantitatively and qualitatively analyzes the spatial congregation and spreading characteristics of diverse LSNFs in Wuhan in 2011, 2014, 2017, and 2020, employing kernel density analysis, average nearest neighbor index, mean center, and distance distribution frequency, seeking to characterize the spatial evolution characteristics of LSNF, alongside examining the trends in distances to city cores, principal adjoining roads, and production and consumption sites. The following conclusions were made: (1) Between 2011 and 2020, various types of LSNFs in Wuhan experienced a pattern characterized by the noticeable coexistence of spatial expansion and agglomeration, particularly visible after 2014. The degree of agglomeration is classified in a descending order as follows: CWC, STN, PSN, and PDN. (2) An “absolute diffusion” phenomenon characterizes the distribution of distances between various kinds of LSNFs and city cores or neighboring roads, with the lion’s share of high-frequency distribution zones spreading beyond city cores by 5–10 km, and a majority of the LSNFs being situated within 1 km from adjacent roads. (3) While the LSNF collective exhibits a stronger tendency towards the consumption facet, it reflects a surrounding of industrial production sites on the production facet and locations of manufactured goods consumption on the consumption facet, followed by locations of agricultural product consumption and comprehensive consumption sites.

Thermal Performance Analysis of a Prismatic Lithium-Ion Battery Module under Overheating Conditions

Thermal runaway (TR) of lithium-ion batteries has always been a topic of concern, and the safety of batteries is closely related to the operating temperature. An overheated battery can significantly impact the surrounding batteries, increasing the risk of fire and explosion. To improve the safety of battery modules and prevent TR, we focus on the characteristics of temperature distribution and thermal spread of battery modules under overheating conditions. The heat transfer characteristics of battery modules under different battery thermal management systems (BTMSs) are assessed. In addition, the effects of abnormal heat generation rate, abnormal heat generation location, and ambient temperature on the temperature distribution and thermal spread of battery modules are also studied. The results indicate that the BTMS consisting of flat heat pipes (FHPs) and bottom and side liquid cooling plates can effectively suppress thermal spread and improve the safety of the battery module.

Motion behavior of a high-current fault electric arc occurred in the dead zone of protection in a substation

Since the dead-zone fault in substations often has a relatively long removal time, it may damage the insulation of power equipment and even threaten the stability of the power system. In this paper, the movement of the dead-zone fault electric arc in a 220-kV substation is investigated. The arc chain model for the dead-zone fault electric arc is developed; the influences of electromagnetic force, thermal buoyancy, and the air resistance stressed on the electric arc are comprehensively considered. The electric arc velocity and displacement are computed. Then, the spreading characteristics of the dead-zone electric arc under various conditions are studied. The spreading trend of the dead-zone fault electric arc is summarized. Finally, measures to inhibit the spreading of the electric arc are suggested. The study indicates that the movement of the electric arc in the dead zone during the early stage is primarily influenced by the electromagnetic force resulting from the overpass and conductor, and the arc is concave and has an irregular trajectory. The inclination angle of the conductor significantly affects the direction of the electromagnetic force. If the conductor is laid horizontally, the electric arc is subjected to a smaller force. The electromagnetic force stressed on the electric arc is mainly attributed to the fault phase conductor and the electric arc body itself, whereas those from the other phase conductors are minor. The initial position of the arc root has a certain impact on the movement of the electric arc. The use of the insulating materials restricts the arc root movement.

Ground motion models for regions with limited data: Data‐driven approach

AbstractThe ground motion model (GMM) for response spectra is crucial to hazard studies and structural design. GMM developed for regions with abundant data can capture appropriate spectral attenuation characteristics. However, several seismically active regions, such as the Himalayas, have limited recorded data, and thus, traditionally, simulated, or other regional data are supplemented with the available data for developing a GMM. Despite data augmentation, GMMs developed for such regions cannot appropriately depict attenuation characteristics. Therefore, the paper presents a comprehensive study encompassing the development of data‐driven approaches to obtain GMM for response spectra using the Himalayan crustal data with inputs: magnitude, distance, site class, depth, and a flag corresponding to the horizontal and vertical components. In this regard, GMM using transfer learning is initially developed from a pre‐trained model using global crustal data. Additionally, GMM using the XGBoost approach with monotonic constraints enforced on inputs is developed. These approaches could not capture trends appropriately. Finally, a monotonic constrained transfer learning model is developed to appropriately depict magnitude saturation and scaling, magnitude‐dependent geometric spreading, anelastic attenuation, depth scaling, site amplification, and other desired characteristics.

Mechanism of boundary bubble drag reduction of Couette flow in nano-confined domain

Bubble drag reduction technology is of great significance in improving the propulsion efficiency of underwater vehicle and reducing the comprehensive energy consumption during navigation. Bubble drag reduction is a highly effective method of reducing the frictional resistance encountered by large ships and underwater vehicles during navigation. It exhibits excellent stability in drag reduction, and has advantages such as environmental friendliness, adaptability to various flow environments, and suitability for all underwater components of ships. Therefore, it is greatly significant to conduct in-depth research on bubble drag reduction and its underlying mechanism. In this work, the flow characteristics and the boundary bubble drag reduction mechanism of gas-liquid Couette flow in parallel wall nanochannels are studied by molecular dynamics method, and the influences of surface wettability, wall roughness, and gas concentration on boundary slip velocity and bubble drag reduction effect are analyzed. The results indicate that the bubble drag reduction effect is enhanced with the increase of boundary slip velocity. In the gas-liquid two-phase flow region, with the increase of shear velocity, the lateral deformation of boundary adsorbed bubble and boundary slip velocity increase, thus enhancing the bubble drag reduction effect. The increase of solid-gas interaction strength and gas concentration can lead to the enrichment of gas atoms near the wall, improve the bubble spreading characteristics on the wall, and thus increase the slip velocity of the solid-liquid interface. The wall roughness can change the spreading characteristics of bubble, affect the boundary slip velocity, and then change the drag reduction effect of the fluid-solid interface. As the rib height increases, gas atoms accumulate in the grooves between ribs and the adsorption quantity of gas atoms on the upper surface of the rib decreases, which leads to the decrease of the boundary slip velocity of the solid-liquid interface and ultimately reduces the drag reduction effect. The research results will provide important theoretical guidance for implementing the boundary drag reduction technology in large ships and underwater vehicles.

An improved propagation model of public opinion information and its governance in online social networks under Omni-media era

<p>During the Omni-media era, the in-depth advancement of intelligent process endowed public opinion information (referred to as public opinion) with unique spreading characteristics, and put forward new and higher requirements for its governance. Against this background, we proposed an improved public opinion propagation model coupling the possible factors to grasp its spreading rules. Then, the spreading characteristics of public opinion and its governance timing-intensity-effect in online social networks (OSN) were discussed through numerical simulations. Our results showed that the propagation of public opinion shows faster speed and is more dependent on netizens' attributes in open OSN with a wider scope and depends more on information content in closed OSN. During the governance process of public opinion propagation, the regulators' strategies should have priority: Governance timing $ \succ $ governance proportion $ \succ $ punishment intensity. Based on research findings, targeted countermeasures and decision-making references were provided for the regulators to reasonably guide the evolution trend of public opinion.</p>

Study on Elevated Interval Evacuation of Metro Train considering the Influence of Fire, Railings, and Track Bed

Elevated metro is a typical type of urban rail transit that operates on viaducts. Due to its fast construction speed and low cost, it plays an important role in transportation systems with dense concentrations of people. Once a fire accident occurs in rush hour, it will cause high casualty and enormous injuries. In this regard, studying the characteristics of fire smoke spread and passengers’ evacuation is of profound significance. In this paper, Pyrosim and Pathfinder software was utilized to simulate metro fire and evacuation process. The variation of temperature, CO concentration, and visibility inside carriage and outside walkaway were studied to explore the characteristic of fire and smoke. Evacuation time, speed, density, and path were analyzed for six cases considering the influence of railing settings on evacuation walkaway and the use of track bed. The impact of smoke on movement speed reduction and temperature on the available door numbers were taken into consideration. Results revealed that the temperature of accident carriage rose to tenability limit after 50 s and the visibility decreased to 5 m within 150 s. CO concentration was below safety criteria due to sufficient oxygen. Temperature was the most important factor that leads to the risk of evacuation, especially inside the accident carriage. The length of evacuation walkaway could highly reduce evacuation time and density. Railings had a negative impact on evacuation while the usage of track bed had a positive effect. Besides, the impact of railings was not as significant as the usage of the track bed. Research results can provide decision‐making reference for fire protection and evacuation design to alleviate congestion and improve safety management.

Epidemiological Characteristics and Trends of Scarlet Fever in Zhejiang Province of China: Population-Based Surveillance during 2004-2022.

Over the past two decades, scarlet fever has resurged in some countries or areas. Nationwide nonpharmaceutical interventions changed the patterns of other infectious diseases, but its effects on the spread of scarlet fever were rarely studied. This study aimed to evaluate the changes in scarlet fever incidence in Zhejiang Province, China, before and during the COVID-19 pandemic periods and to provide references for scarlet fever prevention and control. Scarlet fever surveillance data in Zhejiang, China (2004-2022), were analyzed in three stages. Two-sample z test, ANOVA, and Tukey's test were used to compare and analyze the characteristics of disease spread at different stages. The ARIMA model was used to predict the overall trend. The data were obtained from the National Infectious Disease Reporting Information System. A total of 28,652 cases of scarlet fever were reported across Zhejiang Province during the study period, with the lowest average monthly incidences in 2020 (0.111/100,000). The predominant areas affected were the northern and central regions of Zhejiang, and all regions of Zhejiang experienced a decrease in incidence in 2020. The steepest decline in incidence in 2020 was found in children aged 0-4 years (67.3% decrease from 23.8/100,000 to 7.8/100,000). The seasonal pattern changed, with peak occurrences in April to June and November to January during 2004-2019 and 2021 and a peak in January in 2020. The median duration from diagnosis to confirmation was highest before COVID-19 (4 days); however, it decreased to 1 day in 2020-2022, matching the other two medians. In 2020, Zhejiang experienced an unprecedented decrease in scarlet fever, with the lowest incidence in nearly 18 years, but it rebounded in 2021 and 2022. The seasonal epidemiologic characteristics of scarlet fever also changed with the COVID-19 outbreaks. This suggested that nationwide nonpharmaceutical interventions greatly depressed the spread of scarlet fever. With the relaxation of non-pharmaceutical intervention restrictions, scarlet fever may reappear. Government policymakers should prioritize the control of future scarlet fever outbreaks for public health.

Kinetic characterization of low velocity positive collision of double droplets

Droplet positive collision is a complex process involving heat transfer in gas-liquid-solid three-phase flow and droplet collide dynamics. In order to study the kinetic behavior of droplets under positive collision in low velocity (v < 2 m/s), this paper focuses on the spreading, vibration, and fracture characteristics of double droplets by numerical simulation. First, the accuracy of the model is verified by experimental comparison. The effects of droplet diameters, collision velocities and wall contact angles on the spreading process are analyzed, and the spreading factor curves are plotted. Then, the droplet rebound vibration after collision fusion is equated to a single-degree-of-freedom damped vibration system, and the peak vibration height variation curve of the fused droplet is obtained by non-linear fitting. Considering the droplet phase change, the influence law of different conditions on the vibration damping factor and vibration time of the fused droplet is studied. Finally, it is found that rebound fracture and spreading fracture occur after the fusion of double droplets under positive collision, and the critical values of collide velocity required for the occurrence of the aforementioned phenomenon are found. To provide a reliable theoretical basis for the study of heat and mass transfer processes after multiple droplets collide the wall.

Study on Smoke Spreading Characteristics of Highway Tunnel Fire

In the event of a fire in a road tunnel, the effect of natural smoke exhaust alone is far inferior to that of mechanical smoke exhaust. Study of the characteristics of the flux of smoke gases inside the tunnel with the use of mechanical exhausts in case of sudden fire in road tunnels by means of specific model simulation methods, specific analysis by setting fixed exhaust spacing and different emission volumes, and the addition of fine water mist is studied. The results show that: when the exhaust vent spacing is 30m, the smoke exhaust volume in 30m³/s, 40m³/s, 50m³/s mechanical smoke exhaust device under the action of temperature, CO concentration and visibility will not affect the safe evacuation of the personnel, but taking into account the control of smoke propagation and economic reasonableness, the smoke exhaust volume of 40m³/s is better than the smoke exhaust volume of 30m³/s and 50m³/s. Under the coupling effect of mechanical smoke exhaust system and fine water mist, the spread of smoke in the tunnel can be controlled within a certain range and the internal temperature of the tunnel can be reduced. It can provide a certain basis for the design of the exhaust vent and the setting of water mist in the future.

Investigation of the Occurrence Characteristics and Possible Origins of Daytime Spread F Irregularities in Low Latitude Region

AbstractA study of occurrence characteristics and morphology of daytime spread F (DSF) irregularities was conducted using ionosonde from 2013 to 2020 over low‐latitude Puer station in the China sector. In this study, a day with two or more consecutive F‐region diffuse echo ionograms within one hour from local sunrise to sunset at an altitude of 250 km is considered a DSF day. The results show that the DSF irregularities observed in different solar activity years have a similar seasonal distribution, manifesting as frequent occurrences in June solstice with a maximum occurrence near sunrise. Furthermore, the morphology of most DSFs on the ionograms is predominantly frequency spread F, with a few observed near sunrise as MSF and RSF. In contrast to in high solar activity years (HSAY, 2013–2015), an interesting phenomenon of DSF irregularities in low solar activity years (LSAY, 2016–2020) is presented. That is, in the late afternoon hours (15–18 LT), DSFs have an unexpectedly high occurrence rate during the December solstice. By analyzing the virtual height variations for iso‐frequency plots of the DSF event occurring in the afternoon, these DSF irregularities were found to be likely associated with daytime medium‐scale traveling ionospheric disturbances (MSTIDs). Compared with the observed characteristics of the nighttime spread F, the fossils of nighttime plasma bubbles irregularities might play a key role in the development of DSF occurring in the early morning. At the same time, the influence of daytime MSTIDs on DSF irregularities occurring in the late afternoon hours cannot be ignored.

Spreading process and characteristics of silicone oil with multi-viscosities on calm liquid surface with low temperature: Spreading length, stable thickness and morphology

Oil spreading on the sea has been a great focus, especially along with the intensification of oil development activities in arctic regions, leading to an increase in the frequency of oil spills in extremely cold regions. Currently, the effect of extreme low temperature on oil spreading behavior has not been fully studied, and the applicability of existing models of oil spreading characteristics in low temperature scenarios is not clear. An experimental platform was customized to set up low temperature liquid substrate environments (−20∼20 °C). A series of oil spreading experiments of silicone oil with viscosities of 50, 100, 350 and 1000 cs and five released volumes (1–5 ml) on low temperature substrates were carried out. The effects of experimental variables including temperature, viscosity and volume on oil spreading characteristics of spreading length, stable thickness, morphology, and cone angle were investigated. The entire spreading process of oil was displayed from the top and side views, and gave the variation curves of oil thickness and cone angle with time. Summarized the spreading law for multi-viscosity silicone oils, the values of the pre-exponential coefficient and the power-law exponent were determined, and detailed formulas for calculating the spreading length was proposed. An stable thickness prediction model that integrates all the forces on the oil spreading process was constructed, including surface tension, viscous force, inertia force and gravity. These forces all weakening with time, especially the inertial and viscous forces, which contain time terms, and weaken the most. The heat transfer between the oil and the liquid substrate was also monitored and discussed in the experiments, proposed that low temperatures may hinder the spreading behavior of the oil by decreasing the spreading coefficient of the oil. The findings of this study can provide a theoretical support for the oil spill cleanup.

The interior spreading story of Labrador Sea Water

The unique convective anomalies of Labrador Sea Water (LSW) can be used as advective tracers when assessing equatorward spreading pathways and timescales of LSW. In this study, we explore advective pathways of two LSW classes formed in the 1990s and early 2000s, respectively, along constant neutral density planes. Hydrographic observations showcase the prevalence of both LSW classes within the Atlantic interior, supporting a recirculation feature that branches from the Deep Western Boundary Current (DWBC) at 36°N among other pathways. Spreading characteristics of both LSW classes from the Labrador Sea to the subtropics are reinforced through a spatial pattern analysis of salinity anomalies and geostrophic velocities along the characteristic neutral density planes of each respective LSW class. We observe both classes to advect out of the Labrador Sea to (i) the eastern subpolar region and down the eastern boundary towards the Atlantic interior, (ii) directly into the Atlantic interior likely from an injection by recirculations from the subpolar gyre and DWBC leakage, and (iii) equatorward along the western boundary via the DWBC. Findings highlight the abundance of LSW within the Atlantic interior, not just along the western boundary, suggesting that interior pathways play an influential role on the export of these subpolar climate signals.

Flow structure and impinging interactions of two confined turbulent converging jets in crossflow

In this work, time-resolved particle image velocimetry (TR-PIV) measurements are carried out to study the flow structure and impinging interactions of two confined turbulent converging jets in crossflow, with the upstream and downstream jets inclined at 20° and 170° with respect to the oncoming crossflow direction. Experiments are conducted for fixed dimensionless nozzle separation distance of s=L/D=3, fixed dimensionless nozzle-to-target surface distance of H/D=6.73, fixed duct Reynolds number of Re=3500 and two jets' Reynolds numbers of Rej=3000 and 6000 that correspond to jets'-to-crossflow velocity ratios of rj=3.45 and 6.91, respectively. Flow visualization images showing ensemble-averaged and instantaneous flow distributions and turbulent characteristics including Reynolds stresses and turbulence intensities for equal and non-equal discharge velocities of the jets are presented on several orthogonal planes of the test section. The swirling strength criterion has been employed to identify coherent structures, and cross spectral analysis of the fluctuating velocity signals detecting subharmonic and harmonic sideband frequencies identify the merging and breakup interactions of the evolving coherent structures. The snapshot proper orthogonal decomposition technique (POD) has been applied to extract the dominant vortical structures and to quantify their relative and cumulative energy contributions to the total kinetic energy fluctuation. The spatial structure of the main four POD modes and the temporal projections of these POD coefficients have been explored to understand the spatio-temporal characteristics of the dominant turbulent fluctuations and their spectral characteristics. Our results show the effect of the velocity ratios on the jets' trajectories, penetration, spreading characteristics, crossflow entrainment through the inner and outer shear layers, transverse velocity decay, size of the converging region and location of the combining point. In addition, the dimensionless shedding frequencies of the oscillating combined jet, the developing wall jets and wake vortices have been obtained. Furthermore, it has been shown that for all values of the jets' velocity ratios employed in this study, a recirculation region does not develop in the converging region.

Analysis of Clinicopathological Features on Spread Through Air Spaces of Lung Adenocarcinoma

The biological and molecular characteristics of spread through air spaces (STAS), a newly recognized invasive mode of lung cancer, remain controversial. The aim of this study was to investigate the clinicopathological features and molecular characteristics of STAS in patients with pulmonary adenocarcinoma. A total of 694 resected invasive non-mucinous lung adenocarcinomas diagnosed by clinicopathology from July 2019 to March 2021 in the First Affiliated Hospital of Guangzhou Medical University were collected, and the relationship between STAS and clinicopathological factors was analyzed. The state of protein expression of anaplastic lymphoma kinase (ALK) was detected by immunohistochemical method. Epidermal growth factor receptor (EGFR) was detected by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR). ROS proto-oncogene 1-receptor (ROS1) was detected by reverse transcription-PCR (RT-PCR). A total of 344 STAS positive cases and 350 STAS negative cases were collected. By univariate analysis, STAS positivity was statistically associated with tumor maximum diameter (P<0.001), pleural invasion (P<0.001), lymphovascular invasion (P<0.001), nerve invasion (P=0.013), lymph node metastasis (P<0.001), clinical stage (P<0.001) and histological type (P<0.001). There was a statistical correlation between STAS and ALK protein expression (P=0.001). Multivariate analysis showed that STAS positive was correlated with pleural invasion (P=0.001), vascular invasion (P<0.001), lymph node metastasis (P=0.005)and ALK protein expression (P=0.032). STAS is associated with highly aggressive biological behavior of lung adenocarcinoma, suggesting a poor prognosis.

Rise of social bots: The impact of social bots on public opinion dynamics in public health emergencies from an information ecology perspective

Social bots exacerbate emotional chaos and network disorder during sudden public opinion outbreaks. Drawing on information ecology theory, we analyze how social bots as information person characteristics influence information characteristics represented by topic tendency and sentiment spreading and environmental characteristics represented by information diffusion and network influence, and further discuss the conditional role played by social bots in public opinion dynamics. By comparing different machine learning models, the study selects the XGBoost model with the highest accuracy to identify the type of social bots with specific automation features in the Chinese context. Meanwhile, based on the representative public health emergency, the study uses a large-scale social media dataset (N = 328539) to explore how social bots affect multi-dimensional public opinion dynamics in the information ecosystem. It was found that the information published by social bots and human users has an entirely different dissemination mechanism, and social bots have a significant impact on topic tendency, sentiment spreading, information diffusion, and network influence in cyberspace. Moreover, social bots also play an important moderating role in the information diffusion and network influence of affective information. Relevant findings provide a practical reference for the recognition and prevention of social bots, and help emergency management departments to stabilize public sentiments by intervening in the behavior of social bots, weakening the influence of negative public opinion, and promoting the management of public opinions in emergencies and the maintenance of network order.

Rabies in the Republic of Kazakhstan: spatial and temporal characteristics of disease spread over one decade (2013-2022).

Rabies is a fatal zoonotic disease that remains endemic in Kazakhstan despite the implementation of annual vaccination campaigns. Using data collected over a 10-year time period, the objective of this study was to provide updated information on the epidemiological situation of the disease in the country, and quantitative data on the species-specific spatial distribution of rabies and on the epidemiological features associated with that clustering. Five significant (p < 0.05) clusters of disease were detected. Clusters in southern Kazakhstan were associated with companion animals, which are likely explained by the maintenance of a domestic cycle of the disease in the most densely populated region of the country. Livestock cases were most frequent in clusters in the eastern (where wildlife cases were also frequent) and western regions of Kazakhstan, with higher probability of occurrence in spring and summer, compared to the rest of the year. The results here are consistent with differential patterns for disease transmission in Kazakhstan and will contribute to the design and implementation of zoning approaches to support the progressive control of rabies in the country.