Periodic Fluctuations Research Articles

Industrial technology network security measurement in international trade under discrete hopfield neural network

As global economic integration continues to advance, international trade has become increasingly vital for the economic development and growth of nations. This research aims to assess the trends in industrial technology security within China’s international trade and provide practical guidance for policy-making, corporate strategies, and international cooperation. The significance of the rising trend in security within China’s international trade industry lies in its establishment of a robust foundation for the long-term development of China’s international trade, contributing to its cooperation and competitiveness with other countries. In addressing the limitations of traditional measurement methods and providing a more comprehensive and accurate assessment of industrial technology security, this research presents an approach based on a discrete Hopfield Neural Network (HNN) for evaluating industrial technology security in international trade. This method integrates multiple indicators, including technology gap rates, to construct the Superior Quality Engineering (SQE) comprehensive evaluation model. The research employs a combination model of “entropy-grey relational-Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS)-discrete HNN” to assess industrial technology security. This research evaluates international trade industry technology security using patent data from 2015 to 2022 as samples. The results indicate an overall upward trend in security in China’s international trade industry. Within this trend, the research observes a stepwise increase in scale components, leading to continuous improvement in security. In terms of quality components, although security develops relatively slowly overall, it exhibits a trend of initial gradual decline followed by rapid growth. Regarding efficiency components, there is overall slow growth with periodic fluctuations. This research outcome provides substantial support for the research of industrial technology in international trade. The proposed method can assist businesses in evaluating their technological security in international trade and offer robust support for international trade decision-making.

Intelligent fault diagnosis and security early warning method of new power system based on system network situation

In the past few decades, China’s power demand has been increasing, and the power fiber plays a key role in ensuring the orderly dispatching of all links of the power system. The study used a wavelet decomposition and reconstruction method, which is a signal processing technique used to decompose complex optical power data into low-frequency and high-frequency signals with different frequency components. Through this decomposition, we can more clearly observe periodic fluctuations, trend changes, and noise components in optical power data. The study also examined different prediction models, including GRU, LSTM, ARMA), etc. The performance of these models in predicting optical power trends is then analyzed, taking into account their accuracy, stability, and computational efficiency. Finally, we carefully evaluated the GRU-ARMA combined prediction model and determined its superior performance in predicting optical power trends. The outcomes show that after adjusting the input data length of the gating cycle cell model and the relevant parameters of the autoregressive sliding mean model, the residual mean value was 0.0141. At the same time, the root mean square error calculated by the combined prediction model of the gating cycle unit-autoregressive moving mean model was 0.000618, which successfully improved the accuracy of predicting the optical power trend of power fiber. This research result provides an important reference for the aging state assessment of power fiber lines, and has an important practical application value for the maintenance of power fiber lines.

Mechanism Analysis of the Effect of Wake Vortex on Cylinder Vibration in Flow Induced Motion

Abstract Unsteady Reynolds-averaged Navier–Stokes (RANS) method combined with Spalart–Allmaras turbulence model and dynamic mesh technology was used to investigate the impact of wake vortex on the vibration response of a cylinder. By analyzing the phase difference between the wake vortex force and the displacement under different mass parameters in flow-induced vibration (FIV), the study reveals that the influence of wake vortex on the cylinder varies significantly in different vibration branches. The wake vortex of the initial branch enhances the cylinder's vibration, whereas the wake vortices of the upper, lower, and desynchronized branches suppress the vibration. At the critical point between the initial branch and the upper branch of vortex-induced vibration (VIV), there is a 90 degree phase jump, and the instantaneous phase difference fluctuation between the wake vortex force and displacement of the VIV branch remains relatively constant. In the galloping branch, there are wake vortices in different directions that affect the cylinder's vibration every quarter of the vibration period, and the phase difference undergoes periodic large fluctuations (either in-phase or out-of-phase), with the result that the wake vortex force periodically promotes or restrains the cylinder's vibration, which can serve as a novel criterion for identifying the occurrence of galloping. Furthermore, when varying the mass parameters at a constant reduced velocity, the impact of the wake vortex in the initial branch is relatively insignificant. However, as the mass ratio increases in other vibration branches, the suppressive effect increases, and the wake vortex force can prevent VIV induced galloping phenomenon by affecting the vibration intensity.

Study on rotating stall characteristics of centrifugal pumps based on gamma transition model

The phenomenon of rotating stall in centrifugal pumps is closely associated with the evolution of the blade boundary layer. Aiming to accurately predict the characteristics of the boundary layer, this study investigates the phenomenon of rotating stall in centrifugal pump impellers using the gamma (γ) transition model. The accuracy of the numerical simulation was confirmed by comparing its conclusions with the results of the testing. In calculations considering transition characteristics, the distribution of low-pressure areas inside the impeller is relatively discontinuous, while the pressure distribution is more uniform. However, in calculations without considering transition, the low-pressure regions in neighboring flow channels exhibit a tendency to be interconnected, resulting in a more variable pressure distribution, and the pressure contour at the outlet is closer to parallel. The dynamic characteristics of the centrifugal pump impeller rotating stall were obtained through the dynamic mode decomposition method, including the frequency, structure, and dynamic evolution process of the stall vortex. Through modal reconstruction, it was discovered that the impeller's rotation causes the stall vortex to undergo periodic fluctuations. The stall vortex is not stationary but moves synchronously with the rotation of the blades. At different time points, the stall vortex exhibits periodic changes. At the blade suction entrance, the stall vortex initially appears. Subsequently, multiple vortex structures resulted in channel blockage. After a period of development, the excess vortex structures merge to generate a typical “8” shaped vortex structure and move toward the exit. Finally, the exit stall vortex disappears, and a new vortex structure is generated at the inlet of the blade suction surface.

Permafrost temperature dynamics and its climate relations in various Tibetan alpine grasslands

Permafrost temperature is a vital indicator of climate and permafrost changes, benefiting ecosystem development and informing local climate strategies. Alpine grasslands impact moisture and heat exchange between the surface and atmosphere, thereby affecting the thermal state of underlying permafrost. This study analyzed permafrost temperatures (2004–2019) from various alpine grasslands (including alpine meadow, alpine steppe, alpine desert grassland, and barren land) in the Beiluhe region of the Tibetan Plateau and revealed their connections to climate change and controlling factors, using time–frequency analysis. The findings revealed that in the time–frequency domain, permafrost temperatures exhibited multiple time scales characteristics, driven by climate fluctuations. Changes in the active layer closely followed monthly climate variations, while permafrost dynamics responded to annual climate changes. Significant oscillations with periods of 10–11, 8–9, and 14 years were observed in the surface, permafrost table, and deep permafrost layers, respectively. Among the different types of alpine grasslands, alpine meadows proved to be the most sensitive to climate change, with the intensity of periodic fluctuations initially decreasing and then increasing with depth in alpine meadows, while it consistently decreased with depth in the other three alpine grasslands. The impact of air temperature, precipitation, and wind speed on permafrost dynamics exhibited depth-dependent variations in the time–frequency domain, contrasting with the time domain where permafrost temperature changes were predominantly associated with air temperature across all depths.

Microbial landscape of periodontal pockets against local antibacterial therapy of chronic generalized periodontitis: a multicenter clinical trial

Background. A microbial nature of periodontitis requires an accurate analysis of the pathogenic potential of the periodontal pocket microflora thereby enabling correct diagnosis to be made and the most effective pharmacological agent to be selected for treating chronic periodontitis. Metronidazole demonstrates excellent results for anaerobic microorganisms in the periodontal pocket, whereas minocycline hydrochloride, moxifloxacin and amoxicillin/clavulanate are efficient for aerobic microorganisms. However, specialists find considerably relevant to analyze the correlations between specific bacterial associations in the periodontal pocket against local antibacterial therapy, as well as to track the contents of periodontal pockets long after antibacterial therapy. Therefore, a microbiological analysis of periodontal pocket contents is considered necessary in order to select and monitor the effectiveness of local antibacterial therapy.Objective. To evaluate the effectiveness of local antibacterial therapy for chronic generalized periodontitis by means of analysis of changes in the microbiological composition of periodontal pockets.Methods. The clinical trial involved 144 patients with chronic generalized periodontitis. The study included examination of patients and analysis of clinical data bases of the Department for General Practice Dentistry, Kuban State Medical University and the Dentistry Department, Stavropol State Medical University of the Ministry of Health of the Russian Federation. The trial included patients aged 30 to 60 with a diagnosis of chronic generalized periodontitis of different severity. All periodontitis patients were divided into 2 groups depending on the therapy: main and control groups. Each group had three subgroups depending on the severity of the pathologic process. The first subgroup of the control group (chronic generalized periodontitis of mild degree) consisted of 16 people (11.1%), the second subgroup (chronic generalized periodontitis of moderate degree) — 31 people (21.5%), the third subgroup (chronic generalized periodontitis of severe degree) — 7 people (4.9%). The first, second and third subgroups of the main group consisted of 28 (19.4%), 48 (33.3%) and 14 persons (9.7%) respectively. The severity of periodontitis was determined by the depth of the periodontal pocket, degree of bone resorption (according to x-ray examination), and pathologic tooth mobility. A local anti-inflammatory therapy for the patients of the control group included oral baths with propolis (15–20 drops of 10% propolis tincture diluted in 100 ml of warm water) 3 times a day for 7 days starting from the first visit. At the final stage of treatment after preliminary scaling and rootplaning, patients of the control group received antiseptic gel with 10% metronidazole and 2% chlorhexidine bigluconate to be injected into periodontal pockets with over 4 mm depth. Additionally, applications of adhesive dental films Diplene Denta L (with lincomycin) and Diplene Denta M (with metronidazole) were prescribed to be done in the home. In addition to the above-mentioned comprehensive therapy, patients of the main group received a single insufflation of minocycline hydrochloride microspheres into each periodontal pocket. The tools for the patients of the main group included plastic cannulas with minocycline hydrochloride microspheres in the form of powder in the tip of the cartridge, and a special syringe-insufflator. The technique of antibiotic insufflation into the periodontal pocket was preliminary trained on the model of jaws with the studied pathology. Statistical analysis of the results was performed using variance analysis in the Excel Microsoft Office 2016 (Microsoft, USA).Results. According to the systematic observation of the patients from the control group, periodic fluctuations in microbial population in the majority of pathologic pockets obtained a specific regularity: a decrease in the number of microorganisms on day 21 was followed by its increase in the subsequent period of observation after 30 and especially 60 days. According to the ongoing follow-up of the patients of the main group, fluctuations of microbial population in the majority of pathologic pockets obtained a certain regularity: a significant reduction in the number of microorganisms on day 21 was followed by its slight rise in the subsequent period of observation after 30 and a slight increase again in 60 days. Fluctuations in the number of microorganisms of periodontal pockets in the main group reveal their specific character: their number remained invariably lower than that of the control group throughout the observation period, while the total number of detected periodontopathogens decreased.Conclusion. The established correlations between the main indicators of microbiological status of periodontal pockets and the severity of chronic generalized periodontitis within different periods after the local therapy confirm the positive dynamics of treatment in the main group, where patients were insufflated with minocycline hydrochloride microspheres, proved by a change in the typology of microbial status of periodontal pockets and a number of periodontopathogenic microorganisms.

Reconstructing the Spectrum of a Polyharmonic Signal under Slow Fluctuations in the Sampling Period

Reconstructing the Spectrum of a Polyharmonic Signal under Slow Fluctuations in the Sampling Period

Investigation and analysis of ship to platform collision incidents on the UK continental shelf: highlighting trends between the enforcement of offshore regulations and the occurrence of vessel to platform collision incidents

An offshore installation is exposed to ship collision risk from in-field and passing vessels. Both categories of collision have occurred on the United Kingdom Continental Shelf (UKCS), and both have the potential to result in catastrophic damage to the installation, although to date only significant consequences have been observed in UK waters. World-wide, catastrophic collisions with installations have occurred resulting in severe damage to vessels and installations, leading to loss of life and environmental damage. This led to the authors investigate the occurrence and reporting of ship to platform collisions on the UKCS 1971–2017. It was found that there were periodic fluctuations in the occurrence of collision accidents. This research analyses the accident trends in order to determine the whether the fluctuations were a regular occurrence and, if so, what was the cause. 511 ship to platform collision incidents between 1971 and 2017 were subject to analysis, in terms of damage classification, the vessel type, month of occurrence and a comparison of the release of regulations with the fluctuation of incidents. Subsequently, this analysis has identified a key trend between the reporting of offshore collision incidents and the release and enforcement of offshore Safety Case regulations.

Real-time observation of soliton pulsation and explosion in an Yb-doped fiber laser

Nonlinear dissipative systems support pulsating solutions and exhibit many interesting dynamic behaviors. Here, we report various soliton pulsations and explosions in an all-normal dispersion ytterbium-doped fiber laser by utilizing the dispersive Fourier transform technique. By the different soliton dynamics, these phenomena can be classified into single-soliton pulsation and explosion, dual-soliton synchronous and asynchronous pulsation, as well as dual-soliton asynchronous explosion. Solitons exhibit identical periodic fluctuations in the synchronous pulsation while showing the anti-phase behavior in asynchronous pulsation. The dual-soliton asynchronous pulsation might be related to the periodic modulation of the polarization state of solitons. As for the dual-soliton asynchronous explosion, it can be regarded as the asynchronously triggered transient solitons containing periodic explosion through the gain-mediated soliton interactions. These findings may provide new insights into complex dynamics in the field of ultrafast lasers.

A physics‐informed machine learning prediction for thermal analysis in a convective‐radiative concave fin with periodic boundary conditions

AbstractThe present research is focused on the inspection of unsteady heat dissipation through a radiative‐convective concave profiled fin along with the periodic boundary conditions. Additionally, the long‐short‐term memory machine learning (LSTM‐ML) approach is used in this study to examine the periodic fluctuation in the temperature of the fin. The current research is devoted to solving the highly non‐linear equation using a physics‐informed neural network (PINN) approach. Using the proper dimensionless terms, the associated fin problem is transformed into a non‐dimensional system, and the resulting partial differential equation (PDE) is then numerically solved using the finite difference method (FDM). Using the data‐driven LSTM‐ML technique, the time‐dependent periodic heat transmission in the concave fin is also examined. The impact of various factors on the temperature profile of the concave extended surface is explained, and the results are visually displayed. The temperature distribution in the concave fin diminishes as the convection‐conduction parameter and radiation‐conduction parameter rise. As the amplitude and thermal conductivity parameters improve, so does the temperature of the concave fin. Furthermore, it is demonstrated that although LSTM‐ML and PINN closely matched the FDM findings during the training domain, only PINN with designed characteristics has the potential to predict accurately beyond the trained region by capturing the physics of the problem.

Spatial–temporal patterns of ecological changes in the Dongting Lake region and their responses to climate factors and human activities

ABSTRACT The Dongting Lake region is an important ecological and environmental protection zone in the Yangtze River Economic Belt of China. Long-term monitoring and evaluation of its ecological environment is of great significance. In this study, the spatio-temporal pattern of ecological condition change and its response to climate factors and human activities in the Dongting Lake region was quantitatively analyzed using RSEI (Remote Sensing Ecological Index) model. The primary conclusions are as follows: (1) The temporal pattern of ecological changes has a small fluctuation period (1990–2007) and a continuous improvement period (2007–2020) with an ecological improvement rate of 1.17% per year. (2) The spatial pattern of ecological changes is directly tied to the land use types in this area. 17.36% of the regions with an excellent ecological level are primarily woodland, whereas 4.45% of the areas with a low ecological level are mostly urban. (3) The deterioration in ecological conditions in urban areas is primarily attributable to human activities, whereas the decline in ecological conditions in surrounding mountainous regions and central agricultural regions is primarily attributable to climate factors. Our research provides valuable support for ecological environment monitoring and management strategy formulation in the Dongting Lake region.

The quality of life of patients with chronic obstructive pulmonary disease: a bibliometric analysis.

The quality of life (QOL) of patients with chronic obstructive pulmonary disease (COPD) is garnering increasing attention. However, faced with thousands of relevant clinical literature, it is becoming increasingly difficult for researchers and institutions to identify impactful research. Bibliometrics can help researchers quickly and methodically analyze the impact and hot trends of clinical research, strengthen teamwork, and solve related challenges. Therefore, we used bibliometrics to analyze and visualize data on the QOL of patients with COPD over the past 31 years to understand the key authors, research areas, and future trends. We searched the Web of Science Core Collection for literature published since the establishment of the database. The main subject terms used were "chronic obstructive pulmonary disease", "quality of life" and their different combinations. Articles were selected and exported in plain text format along with citation information. Bibliometric analysis and data visualization were performed using the R package "bibliometrix" and by incorporating statistical indicators such as the number of publications, citations and outputs of core authors, author collaborations, major journals, major research countries and collaborations, and key research themes. The bibliometric analysis included 9,219 articles. Document type is unlimited. All publications were published between 1992 and 2022, and the number of published articles increased consistently each year over the past decade, with periodic fluctuations. The European Respiratory Journal and the International Journal of Chronic Obstructive Pulmonary Disease emerged as the most frequently cited journals within this domain. Key authors contributing to this field include Wedzicha JA, Jones PW, Singh D, Holland AE, and Wouters EFM. The United States and the United Kingdom exhibited a high volume of publications, high citation rates, and relatively intense international collaboration in related areas, followed by China, Spain, Canada, and Australia in these metrics. Notably, prominent topics within this field included emphysema, pulmonary rehabilitation, dyspnea, acute exacerbation, living status, and mortality, among others. Future research in this field will focus on microorganisms, particulate matter, family rehabilitation, and Tai Chi. This bibliometric analysis highlights the growing importance of QOL research in the field of COPD, which can inform clinicians, researchers, and policymakers to prioritize areas for future investigation in order to develop comprehensive, patient-centered strategies. At the same time, it is suggested that researchers should pay more attention to the core authors, strengthen international collaboration and team exchanges, actively explore characteristic clinical featured treatment measures such as Tai Chi and family rehabilitation, carry out clinical research on the integration of traditional Chinese and Western medicine and self-management, focus more on the QOL, mental health and economic and social burden of patients, and ultimately enhance the well-being of individuals with chronic respiratory diseases.

Study on the performance of a floating horizontal-axis tidal turbine with pitch motion under wave–current interaction

Waves can induce motion in the floating platforms that support tidal turbines, affecting their hydrodynamic loads. To study the non-constant hydrodynamic of floating tidal turbines in a wave condition, this paper investigates the effect of pitch motion on the power coefficient (CP), thrust coefficient (CT), and wake flow of a tidal turbine using computational fluid dynamics. A pitch motion experiment is designed to verify the validity of the numerical method. The results show that the CP and CT exhibit periodic fluctuations under pitch motion, with the fluctuation period being consistent with the pitch period. Waves do not change the overall fluctuation trend of the CP and CT, but they do complicate the fluctuations and increase the likelihood of blade fatigue damage. Pitch motion reduces the mean power, with large-amplitude pitch motions particularly likely to result in severe power loss. The low-velocity region of the wake under pitch motion exhibits significant periodic oscillations. The wake is more susceptible to the pitch period than the pitch amplitude, and small-period pitch motions force the wake to deform earlier, accelerating wake vortex dissipation and velocity recovery. Increasing the immersion depth reduces the effect of waves on tidal turbine performance, but is not conducive to wake recovery. In summary, the rational design of the immersion depth and limiting the movement amplitude of the floating platform have the potential to prolong the working life of tidal turbines and increase their power output.

Measuring the Magnetic Dipole Moment and Magnetospheric Fluctuations of SXP 18.3 with a Kalman Filter

The magnetic dipole moment μ of an accretion-powered pulsar in magnetocentrifugal equilibrium cannot be inferred uniquely from time-averaged pulse period and aperiodic X-ray flux data, because the radiative efficiency η 0 of the accretion is unknown, as are the mass, radius, and distance of the star. The degeneracy associated with the radiative efficiency is circumvented if fluctuations of the pulse period and aperiodic X-ray flux are tracked with a Kalman filter, whereupon μ can be measured uniquely up to the uncertainties in the mass, radius, and distance. Here, the Kalman filter analysis is demonstrated successfully in practice for the first time on Rossi X-ray Timing Explorer observations of the X-ray transient SXP 18.3 in the Small Magellanic Cloud (SMC), which is monitored regularly. The analysis yields μ=8.0−1.2+1.3×1030Gcm3 and η0=0.04−0.01+0.02 , compared to μ=5.0−1.0+1.0×1030Gcm3 as inferred traditionally from time-averaged data assuming η 0 = 1. The analysis also yields time-resolved estimates of two hidden state variables, the mass accretion rate and the Maxwell stress at the disk–magnetosphere boundary. The success of the demonstration confirms that the Kalman filter analysis can be applied in the future to study the magnetic moments and disk–magnetosphere physics of accretion-powered pulsar populations in the SMC and elsewhere.

Assessing the impact of climate change on landslide recurrence intervals in Nakhon Si Thammarat Province, Thailand, using CMIP6 climate models

Climate variability and climate change may influence the frequency and recurrence interval of landslides. Precipitation, as a main triggering factor of landslides, may be influenced by climate variability and climate change. Changes in precipitation may directly affect landslide frequency and recurrence intervals. Considering the influence of climate variability and climate change, the partial duration series method and critical rainfall threshold are combined with the simulated precipitation of Phase 6 of the Coupled Model Intercomparison Project (CMIP6) general circulation models (GCMs) to predict changes in future landslide recurrence intervals in Nakhon Si Thammarat Province, Thailand. The analytical results predicted changes in the landslide frequency over the next 20 years (2023 to 2042). SSP1–2.6 and SSP2–4.5 are adopted as future socioeconomic development scenarios. According to the predictions, the results showed that the return period of landslide occurrence in the future will be shorter than the return period of landslide occurrence in the historical period; moreover, the landslide recurrence interval will fluctuate greatly. The Nakhon Si Thammarat DWR meteorological station shows the most fluctuation in landslide recurrence intervals for SSP1–2.6. In addition, the Nakhon Si Thammarat meteorological Station experiences a significant decrease of approximately 35% in landslide recurrence intervals under SSP1–2.6. For SSP2–4.5, the Nakhon Si Thammarat meteorological station shows the most fluctuation in landslide return period. In addition, the Nakhon Si Thammarat meteorological station observed a decline in landslide recurrence intervals, with a reduction of approximately 40%. Hence, the frequency of landslides may increase in the future. A comparison between SSP1–2.6 and SSP2–4.5 revealed that SSP2–4.5 yielded lower landslide return periods.

Temporal dynamics and forecasting of aerosol optical depth in megacities Lahore and Karachi: Insights from the Indo-Gangetic Basin and southern Pakistan, and implications for Sustainable development

This scientific study investigates the temporal dynamics and forecasts aerosol optical depth (AOD) in Lahore and Karachi, Pakistan's two most populated cities. Lahore, in the center of the Indo-Gangetic Basin, and Karachi, on the southern coast, have issues from growing urbanization and significant aerosol emissions. Understanding AOD trends is critical for successful environmental management, public health planning, and climate change mitigation. Using the Box-Jenkins ARIMA models, this work systematically analyses monthly AOD fluctuations from July 2002 to May 2023 to confirm their predicting accuracy. The autocorrelation function (ACF) and partial autocorrelation function (PACF) have been employed to estimate the suitable model and identify significant lags to maintain prediction accuracy. The study concludes with a judgment that Model A is ideal for the ecology of Karachi and Model B for the ecology of Lahore. The forecast till January 2030 is available to look at several trends on AOD, namely, periods of seasonal solid fluctuations for both sites. This diversity emphasizes the need for specific actions, such as stricter environmental regulations, air quality monitoring, and providing greener transport solutions, which will result in blue skies. Utilizing the in-depth observations and forecast of the changing distribution of AOD values, the study helps develop approaches for reducing aerosol pollution. This is also one of the key contributions. We investigated critical environmental problems in the cities of Karachi and Lahore and provided means for such issues' resolution, enabling sustainable development and clean air.

Effects of constant high water levels in winter on waterbird diversity in Caizi Lakes: A functional perspective

The middle and lower Yangtze River floodplain lakes are important stopover and wintering sites for migratory birds on the East Asian–Australasian Flyway. The periodic water level fluctuation of the lakes plays a critical role in the aggregation of waterbirds. However, the construction of a series of gates and dams has impeded the hydrological connectivity between rivers and lakes and disrupted the natural water level fluctuation patterns of lakes. The water level status of lakes influences determines their habitat utilization by waterbirds. In recent years, Caizi Lakes, the gate-controlled lake connected to the Yangtze River due to the need for water level regulation requirements, has experienced sustained high water levels in winter, which can reduce habitat quality and in turn influence waterbirds activity. In the present study, wintering waterbirds in Caizi Lakes were surveyed during the 2021–2022 (W1) and 2022–2023 (W2) wintering periods. Moreover, we explored the effects of constant high water levels in winter on waterbird assemblages we explored by comparing species richness, abundance, and functional waterbird diversity. Correlation analyses were then performed to elucidate the relationship between habitat factors and water level changes during the wintering period of migratory birds and between changes in various habitat factors and wintering waterbird assemblages under different hydrological conditions. The results showed that functional beta diversity was more sensitive to changes in waterbird assemblages in Caizi Lakes than functional alpha diversity. Moreover, constant high water levels in the mid-wintering period decreased suitable habitats for wintering waterbirds, increased functional turnover among waterbird assemblages, increased total dissimilarity among assemblages significantly, and decreased the level of functional nestedness significantly. Additionally, the areas of the three wetland habitats in Caizi Lakes were significantly correlated with water level changes during W1 and relatively less affected by water level changes under constant high water level conditions during W2. The changes in habitat area were influenced primarily by anthropogenic activities, with an increase in meadow area favorable for assemblage species richness and abundance, as well as functionally nested components. Water level regulation should take into consideration the natural hydrological rhythms of the declining water level to ensure that adequate and suitable habitats are provided for wintering waterbirds.

Tracking the Nearfield Evolution of an Initially Shallow, Neutrally Buoyant Plane Jet Over a Sloping Bottom Boundary

AbstractUnderstanding coastal plane jets which occur when a body of water discharges into an ocean or a lake through a channel or outlet is important, since they play a significant role in sediment, nutrient, and pollutant exchange. This study investigates the nearfield of initially shallow, neutrally buoyant plane jets, bounded by a free surface and a sloping bottom (Sloping Bottom Jet; SBJ) that issue into a laterally unconfined quiescent ambient both experimentally and numerically, and compares them with a plane jet flowing over a horizontal bottom (Horizontal Bottom Jet; HBJ). Results revealed that, different from the HBJ, the width and centerline velocity of SBJ decrease near the mouth. The SBJ width gradually increases after that as the transverse longitudinal velocity profile progressively transforms from a “top‐hat” into a Gaussian distribution. Once the Gaussian distribution is established, both jets diverge and centerline velocity decreases. Shear layers are generated on the sides of both jets with Kelvin Helmholtz‐type Coherent Structures (KHCS) developing inside. KHCS produce periodic velocity fluctuations with a Strouhal number of ∼0.079 and contribute significantly to momentum exchange and turbulent kinetic energy production. Since the thickness of the SBJ increases longitudinally, the vertical extent of KHCS also increases. When the two shear layers meet and merge at the centerline, they cause a flapping motion of the jet. This location is closer to the jet mouth for SBJs than for the HBJ. These findings demonstrate that a sloping bottom modifies the flow field from quasi‐2D for the HBJ to strongly 3D for SBJs.

Numerical investigation on unstable oscillation of oxygen jet condensation in cryogenic liquid rocket

Oxygen jet condensation always occurs with intense unstable oscillation in the cryogenic delivery pipe of a space launch vehicle. This phenomenon threatens the safety of the propulsion pipeline. It is essential to explore the transient physical features of oxygen jet condensation precisely, including the spectrum of pressure oscillation. Aiming at a deeper understanding of the thermal hydraulic characteristic of oxygen jet condensation, abundant simulations are carried out using a modified phase change method. In this model, the height function method is introduced to capture the interfacial curvature to reveal the mechanism of periodic fluctuation. The simulation proves that three typical flow patterns are found at variant operating conditions in oxygen jet condensation: chugging, oscillation, and swinging. The condensation regime diagram is summarized according to the flow pattern distribution. The chugging flow, along with the phenomenon of liquid oxygen sucked-back flow, shows the most intense pressure oscillation with a maximum amplitude of 133 kPa. In the oscillation flow, the oxygen vapor plume shrinks periodically with a low frequency of about 10 Hz. The swinging flow is a stable flow pattern with a slight pulsation of oxygen vapor plume wake. Its amplitude of pressure oscillation is approximately 1–3 kPa. The influence of liquid oxygen mass flow rate and subcooling on the unstable characteristic is also obtained. These findings offer ample theoretical direction for the development of the space launch vehicle.

AR-V7 expression facilitates accelerated G2/M phase transition in castration-resistant prostate cancer

The emergence of AR-V7, a truncated isoform of AR upon androgen deprivation therapy treatment, leads to the development of castration resistant prostate cancer (CRPC). Understanding mechanisms that regulate AR-V7 expression is critical for developing newer therapeutic strategies. In this study, we have investigated the regulation of AR-V7 during cell cycle and identified a distinct pattern of periodic fluctuation, peaking during G2/M phase. This fluctuation correlates with the expression of Cdc-2 like kinase 1 (CLK1) and phosphorylated serine/arginine-rich splicing factor 1 (p-SRSF1) during these phases, pointing towards their role in AR-V7 generation. Functional assays reveal that CLK1 knockdown prolongs the S phase, leading to altered cell cycle distribution and increased accumulation of AR-V7 and pSRSF1 in G1/S phase. Conversely, CLK1 overexpression rescues AR-V7 and p-SRSF1 levels in the G2/M phase, consistent with observed cell cycle alterations upon AR-V7 knockdown and overexpression in CRPC cells. Furthermore, overexpression of kinase-deficient CLK1 mutant leads to diminished AR-V7 levels during G2/M, underlining the essential contribution of CLK1's kinase activity in modulating AR-V7 expression. Collectively, our findings, for the first time, show periodic regulation of AR-V7 expression, its effect on cell cycle progression and the critical role of CLK1-pSRSF1 axis in modulating AR-V7 expression throughout the cell cycle.