Search Results (36)

The drying process of microcrystalline cellulose and adipic acid particles in a cylindrical fluidized bed was investigated using the Gaussian spectral technique to monitor fluid–dynamic regime transitions associated with surface moisture loss. Pressure fluctuation signals were recorded and analyzed to assess hydrodynamic behavior. Excess moisture significantly alters the bubbling characteristics of the bed, leading to instability in the fluidization regime. The results demonstrated that the Gaussian spectral technique effectively captured these hydrodynamic changes, particularly at the critical moisture content threshold, when compared with the drying rate curves of the materials. For microcrystalline cellulose and adipic acid particles, it is reasonable to conclude that a mean central frequency above 5.75–6.0 Hz and a standard deviation exceeding 3.7–3.8 Hz correspond to a bubbling regime, indicating that the critical drying point has been reached. This approach provides a non-intrusive and sensitive method for identifying transitions in the drying process, offering a valuable tool for real-time monitoring and control. The ability to track fluidization regime changes with high precision reinforces the potential of this technique for optimizing drying operations in the pharmaceutical, food, and chemical industries. Full article

The thrust system, an important subsystem of a tunnel boring machine (TBM), primarily provides thrust force and adjusts TBM’s attitude in real time. In the tunneling process, only controlling the thrust speed causes pressure oscillations, increases soil deformation, and leads to surface subsidence or upheaval. Conversely, solely relying on pressure control causes fluctuations in speed, making it difficult to ensure that the deviation between the designed tunneling axis (DTA) and the actual tunneling axis (ATA) remains within the permissible range. Due to the increase in geological complexity and higher construction quality standards, primarily relying on single-mode speed or pressure control has become inadequate to meet operational demands. Therefore, to realize higher safety and precise trajectory tracking, it is necessary to ensure speed and pressure compound control for thrust systems. This paper proposes a novel adaptive sliding mode control (ASMC) strategy for thrust systems, which is composed of a proportional pressure relief valve (PPRV) and a proportional flow control valve (PFCV). Firstly, PPRV and PFCV are modeled as a second-order system and an ASMC is employed to control the pressure and speed. Next, to assess the performance of the ASMC controller, simulation experiments were conducted under various conditions, including speed regulation, sudden changed load, and disturbed load. The simulation results indicate that compared to the Proportion–Integral–Differential (PID) controller, the ASMC controller shows almost no overshoot in speed and pressure control during the initial stages, with the response time reduced by approximately 70%. During speed regulation process and sudden changed load process, the response time for both speed and pressure control is shortened by about 80%. In the disturbed load process, the ASMC controller maintains pressure stability. In conclusion, the ASMC controller significantly improves the response speed and stability of the thrust system, exhibiting better control performance under various operating conditions. Full article

This study investigates the impact of various water supply modes on the hydraulic reliability of large-scale irrigation networks. An EPANET hydraulic model was developed to simulate the performance of the irrigation network under three supply modes: segmented, uniform, and random water supply. Three key indicators were selected to evaluate the hydraulic reliability of the pipeline network under each mode: Water Supply Uniformity C_u, Pressure Reliability H_k, and Velocity Reliability $\left|v\right|$. These parameters were standardized using the min-max normalization method, and the resulting reliability scores were scaled to a unified range of 0–5, where higher values indicate greater system reliability. The results demonstrate that the EPANET model effectively simulates the hydraulic performance of large-scale irrigation networks. Specifically, under the segmented water supply mode, the reliability values for water supply uniformity, node pressure head, and flow velocity are 4.04, 0.84, and 0.64, respectively. Under this mode, significant flow deviations and pressure head fluctuations occur between the branches, with flow velocities typically exceeding the optimal range. Furthermore, the node pressure head at the branch inlets fails to meet the required minimum pressure head (H_min), indicating potential operational inefficiencies. In the uniform water supply mode, the highest reliability values are observed for water supply uniformity (4.76) and flow rate (4.49), with node pressure head reliability (0.94) slightly surpassing that of the segmented mode. Pressure head fluctuations and flow deviations are significantly reduced, with flow velocities generally aligning with the economic flow rates of the pipeline. However, despite these improvements, many nodes still fail to meet the required minimum pressure head, indicating limitations in meeting demand under peak conditions. In the random water supply mode, node pressure head reliability reaches its highest value (1.54), while water supply uniformity and flow rate reliabilities are 3.99 and 2.50, respectively. Flow deviations and pressure head fluctuations are comparable to those observed in the uniform supply mode. Notably, a higher proportion of nodes meet the minimum pressure head requirement compared to the uniform mode. Overall, the hydraulic reliability of the pipeline network is highest under the uniform water supply mode (2.83), followed by the random water supply mode (2.49), with the segmented water supply mode exhibiting the lowest hydraulic reliability (1.79). These findings provide valuable insights for the selection of optimal water supply modes and the assessment of hydraulic reliability in large-scale irrigation systems. Full article

This article investigates the effects of roof opening and closure conditions on the mean and fluctuating wind pressure coefficient of the roof surface through rigid model wind tunnel tests and further explores the non-Gaussian characteristics of wind pressure (skewness, kurtosis, and wind pressure probability density) under the two conditions. Then, based on the non-Gaussian characteristics under two working conditions, this paper constructs a Hermite moment model to solve the peak factor of the roof surface to evaluate the impact of roof opening and closure on the most unfavorable extreme wind pressure. The research results show that under the two working conditions of roof opening and closure, the windward leading edge’s mean and fluctuating wind pressure coefficients change most significantly, leading to an increase in the degree of flow separation at the windward leading edge. This causes the skewness, kurtosis, and probability density function of the wind pressure at the windward leading edge of the roof to deviate significantly from the standard Gaussian distribution, exhibiting strong non-Gaussian characteristics. Meanwhile, based on the Hermite moment model, it is found that the peak factor of most measuring points is concentrated between 3.5 and 5.0 under both roof opening and closure conditions, significantly higher than the recommended value of 2.5 in GB 50009-2012. In addition, under roof opening, the most unfavorable negative pressure coefficient is −4.54, and the absolute value of its most unfavorable negative pressure extreme is 1.3% higher than the roof opening closure condition. Full article

Background and Objectives: Systolic blood pressure (SBP) variability has been increasingly associated with cardiovascular outcomes, including stroke. This study aimed to evaluate the association between visit-to-visit SBP variability and the risk of ischemic and hemorrhagic stroke. Materials and Methods: A prospective cohort study was conducted on a set of 208 hypertensive patients over a period of three years, from August 2021 to September 2024, at the County Emergency Hospital “Pius Brinzeu”, Timișoara. Patients included in the study were stroke-free. SBP variability was quantified as the standard deviation of SBP measurements obtained quarterly. Results: This study demonstrated that systolic blood pressure (SBP) variability serves as a robust predictor of stroke incidence, underscoring its important role in cerebrovascular risk. The study cohort had an average age of 65.3 ± 9.1 years, with 53.4% males and 46.6% females. Patients in the highest SBP variability group had a 1.21-fold increased risk (21%, p = 0.031) of ischemic stroke and a 1.73-fold increased risk (73%, p = 0.005) of hemorrhagic stroke compared to those in the lowest variability group, revealing that higher SBP variability is strongly associated with an increased risk of both ischemic and hemorrhagic strokes, with the relationship being particularly pronounced for hemorrhagic stroke. Patients exhibiting greater fluctuations in SBP experienced significantly earlier stroke events and reduced stroke-free survival. Moreover, mortality rates were notably higher among individuals with very high SBP variability, indicating its profound impact on long-term outcomes. Conclusions: Visit-to-visit SBP variability is a significant and independent predictor of both ischemic and hemorrhagic stroke, emphasizing the clinical importance of monitoring and managing blood pressure stability. Further research should explore interventions to mitigate SBP variability and its impact on cerebrovascular outcomes. Full article

The implementation of differentiated governance for agricultural water pollution (AWP) plays a significant role in alleviating the pressure on agricultural water resources. However, research that comprehensively assesses AWP and its influencing factors from a multidimensional perspective remains relatively limited. This study utilized the grey water footprint (GWF) model to quantify the agricultural grey water footprint (AGWF), agricultural grey water footprint efficiency (AGWFE), agricultural grey water footprint intensity (AGWFI), and agricultural water pollution level (AWPL) in Zhejiang from 2010 to 2020. Subsequently, we applied the standard deviational ellipse (SDE), the kernel density estimation (KDE), and the Dagum Gini coefficient to delve into the dynamic evolution and regional disparities of these indicators. Ultimately, we leveraged both the random forest model and the panel regression model to identify and examine the key factors shaping AGWF-related indicators. The results show that: (1) From 2010 to 2020, in Zhejiang, both AGWF and AGWFI exhibit a trend of first increasing and then decreasing, peaking in 2012. In contrast, AGWFE has consistently increased over the years, reaching an increase of 54.56 CNY/m³ by 2020. Meanwhile, despite fluctuations, AWPL in Zhejiang shows an overall gradual decline. (2) The centroids of relevant indicators for AWP in Zhejiang are primarily located in Jinhua (for AGWF and AGWFI), Shaoxing (for AWPL), and in the area where AGWFE converge. (3) Compared to 2010, the regional disparities in AGWF and AWPL have shrunk significantly in 2020, whereas the regional differences in AGWFE and AGWFI have increased to some extent. In most years, the regional disparities in AGWF, AGWFI, and AWPL are more pronounced in Northeastern Zhejiang compared to the southwestern part. (4) The influencing factors of AGWF, AGWFE, and AGWFI exhibit significant regional heterogeneity. In Northeastern Zhejiang, the primary factors influencing them are technological innovation, resource endowment, and crop-cultivation methods. Conversely, in the southwestern region, the primary factors exerting the same influence are the application intensities of fertilizers, pesticides, and agricultural film application. The primary drivers of AWPL in Zhejiang are grain yield, water resource availability, and crop-planting structure. Notably, these factors do not exhibit regional heterogeneity. The paper proposes AWP control policies from both a comprehensive and multi-dimensional perspective. Full article

Background: A standard method of assessing postural control is to measure while standing. However, its implementation is usually limited. Recording postural control directly on the trunk in a seated position could provide an alternative diagnostic method for quantifying neuromuscular control. Methods: A comparison of center of pressure (CoP) measurements in the standing and sitting positions was performed on 66 healthy adult subjects. The reliability of the measurements in the sitting position was tested in 23 subjects. In addition, the extension force of all test subjects was recorded. Results: The assessments of CoP fluctuations in standing and seated positions showed adequate agreement (deviation 9.1%). Furthermore, good internal consistencies with a sufficient test–retest reliability could be demonstrated for the measurements in seated position. Both CoP measurement methods showed a comparable Spearman correlation to obtained extension force measurements (standing: 0.24, seated: 0.23). Conclusions: Our results show that recording CoP fluctuations in the sitting position is a reliable and valid adjunct to single-leg stance measurements. It could serve as an additional alternative to quantify neuromuscular control in impaired patients who cannot adequately perform the single-leg stance. In addition, measurement in the seated position allows direct recording of neuromuscular control at the trunk. Full article

Prolonged exposure to high-intensity noise environments in urban rail transit systems can negatively impact the health and work efficiency of drivers. However, there is a lack of comprehensive understanding of the noise pattern and, therefore, effective mitigation strategies. To control the noise in urban rail transit systems, this study proposes a comprehensive noise assessment framework, including metrics such as average sound pressure level, peak sound pressure level, percentile sound pressure levels, dynamic range, main frequency component, and cumulative time energy to evaluate the noise characteristics. We also employ a density-based spatial clustering of applications with noise (DBSCAN) method to identify the noise patterns with the evaluation of their hazard to urban rail transit drivers. The results have revealed that: (1) The equivalent continuous sound pressure level (Leq) in the cab of Lanzhou Urban Rail Transit Line 1 averages 87.12 dB, with a standard deviation of 8.52 dB, which reveals a high noise intensity with substantial fluctuations. (2) Ten noise patterns were identified, with frequencies varying from 14.47 Hz to 69.70 Hz and Leq varying from 60 dB to 115 dB. (3) The major noise sources from these patterns are inferred to be the train’s mechanical systems, wheel–rail interaction, aerodynamic effects, and braking systems. Combined with the noise patterns and urban rail transit’s operation environment, this study proposes tailored mitigation strategies for applications aimed at protecting drivers’ hearing health, enhancing work efficiency, and ensuring driving safety. Full article

Increased intraocular pressure (IOP) is the most important risk factor for glaucoma. The role of IOP fluctuation, independently from elevated IOP, has not yet been confirmed in glaucoma. We investigated the effects of IOP fluctuation itself on retinal neurodegeneration. Male rats were treated with IOP-lowering eyedrops (brinzolamide and latanoprost) on Mondays and Thursdays (in the irregular instillation group) or daily (in the regular instillation group), and saline was administered daily in the normal control group for 8 weeks. The IOP standard deviation was higher in the irregular instillation group than the regular instillation group or the control group. The degree of oxidative stress, which was analyzed by labeling superoxide, oxidative DNA damage, and nitrotyrosine, was increased in the irregular instillation group. Macroglial activation, expressed by glial fibrillary acidic protein in the optic nerve head and retina, was observed with the irregular instillation of IOP-lowering eyedrops. Microglial activation, as indicated by Iba-1, and the expression of TNF-α did not show a significant difference between the irregular instillation and control groups. Expression of cleaved caspase-3 was upregulated and the number of retinal ganglion cells (RGCs) was decreased in the irregular instillation group. Our findings indicate that IOP fluctuations could be induced by irregular instillation of IOP-lowering eyedrops and this could lead to the degeneration of RGCs, probably through increased oxidative stress and macrogliosis. Full article

Background: A relationship between glaucoma and epiretinal membrane (ERM) has been suggested previously. We investigated the association between intraocular pressure (IOP) fluctuation and idiopathic ERM in patients with glaucoma or glaucoma suspect. Methods: Among patients with glaucoma or glaucoma suspect, data from 43 patients with ERM and 41 patients without ERM were reviewed and analyzed in this retrospective study. The long-term fluctuation of IOP was defined based on the standard deviation of IOP across all visits. Results: Patients with ERM were older and had a higher SD of IOP and a higher proportion of having a history of cataract surgery and greater macular thickness (p = 0.018, 0.049, 0.013, and <0.001, respectively). In multiple logistic regression analysis, the high-IOP-fluctuation group was associated with the presence of ERM (p = 0.047). Among patients with ERM, eyes with stage-3 or -4 ERM had worse visual field defects based on mean deviation than those with stage-1 or -2 ERM (p = 0.025). Conclusions: Long-term IOP fluctuation was associated with idiopathic ERM in patients with glaucoma or glaucoma suspect. Idiopathic ERM could serve as a biomarker for long-term IOP fluctuation in glaucoma patients, particularly in clinics where measuring long-term IOP fluctuation during the first visit is not feasible due to its time-consuming nature. Full article

Scientifically measuring the level of environmental governance (EGL) and understanding its spatial convergence has important reference value for ecological governance. In this paper, the global entropy method is applied to measure the EGL of 284 prefecture-level cities in China from 2007 to 2019, which are divided into three major river basins, including the Yellow River, Yangtze River, and Pearl River, to observe the spatial–temporal evolutionary characterization through a standard deviation ellipse model. The coefficient of variation and the spatial econometric model are the tools used to conduct the spatial convergence test. The results are as follows: (1) China’s EGL is low overall, though it is fluctuating upward at low magnitude, and the three major river basins follow the ranking: The Pearl River Basin > The Yangtze River Basin > The Yellow River Basin. (2) Spatially, the distribution pattern of China’s EGL changes from “scattered and sporadic” to “multipolar core”. (3) The center of China’s environmental governance was concentrated in the east from 2007 to 2019, and the EGL in the midstream and downstream regions of the three major river basins increased rapidly. (4) Environmental governance in China has significant absolute and conditional β-convergence characteristics, as do the three major basins, while the ranking of convergence speed remains “Yangtze River Basin > Yellow River Basin > Pearl River Basin”. Of these, economic development accelerated the convergence rate of environmental governance in China and its three major river basins; financial pressure significantly inhibited the convergence of the EGL of the Yellow River Basin. The improvement of the EGL in the Pearl River Basin was also negatively influenced by the industrial structure. Full article

The purpose of this study was to examine the cross-over influence of lower limb fatigue on postural control. Using two experiments, cross-over fatigue was investigated using a proximal (Experiment 1—single-leg squat) and distal (Experiment 2—calf raise) muscle group. In Experiment 1, 15 healthy young participants underwent a single-leg standing task on both the right and left leg, with variations of having eyes open or closed and on stable or unstable surfaces, performing each task for 30 s. For Experiment 2, 20 individuals performed single-leg balance testing for the right and left leg and stable and unstable surfaces. Center-of-pressure data were collected during the balance tasks and were analyzed with linear (standard deviation) and nonlinear (detrended fluctuation analysis) metrics. The results lacked significant differences (p > 0.05) for cross-over fatigue effects on the non-exercised limb, which exhibited similar levels of postural sway between the pre- and post-fatigue balance tests. These tasks may have lacked an appropriate level of duration or intensity to cause a significant effect of central fatigue on the nervous system. The findings underscore the need to better understand how a specific fatiguing task during unilateral rehabilitation may alter postural control. Full article

Earth observations from remotely sensed data have a substantial impact on natural hazard surveillance, specifically for earthquakes. The rapid emergence of diverse earthquake precursors has led to the exploration of different methodologies and datasets from various satellites to understand and address the complex nature of earthquake precursors. This study presents a novel technique to detect the ionospheric and atmospheric precursors using machine learning (ML). We examine the multiple precursors of different spatiotemporal nature from satellites in the ionosphere and atmosphere related to the Turkey earthquake on 6 February 2023 (Mw 7.8), in the form of total electron content (TEC), land surface temperature (LST), sea surface temperature (SST), air pressure (AP), relative humidity (RH), outgoing longwave radiation (OLR), and air temperature (AT). As a confutation analysis, we also statistically observe datasets of atmospheric parameters for the years 2021 and 2022 in the same epicentral region and time period as the 2023 Turkey earthquake. Moreover, the aim of this study is to find a synchronized and co-located window of possible earthquake anomalies by providing more evidence with standard deviation (STDEV) and nonlinear autoregressive network with exogenous inputs (NARX) models. It is noteworthy that both the statistical and ML methods demonstrate abnormal fluctuations as precursors within 6 to 7 days before the impending earthquake over the epicenter. Furthermore, the geomagnetic anomalies in the ionosphere are detected on the ninth day after the earthquake (Kp > 4; Dst < −70 nT; ap > 50 nT). This study indicates the relevance of using multiple earthquake precursors in a synchronized window from ML methods to support the lithosphere–atmosphere–ionosphere coupling (LAIC) phenomenon. Full article

Airfoil noise due to pressure fluctuations impacts the efficiency of aircraft and has created significant concern in the aerospace industry. Hence, there is a need to predict airfoil noise. This paper uses the airfoil dataset published by NASA (NACA 0012 airfoils) to predict the scaled sound pressure using five different input features. Diverse Random Forest and Gradient Boost Models are tested with five-fold cross-validation. Their performance is assessed based on mean-squared error, coefficient of determination, training time, and standard deviation. The results show that the Extremely Randomized Trees algorithm exhibits the most superior performance with the highest Coefficient of Determination. Full article

Introduction: Large hemispheric infarction (LHI) can lead to fatal complications such as malignant brain edema (MBE). We aimed to investigate the correlation between heart-rate-to-blood-pressure ratios and MBE or one-month death after LHI. Methods: We prospectively included LHI patients from a registered cohort. Hourly heart-rate-to-blood-pressure ratios were recorded as a variation of the traditional shock index (SI), SI_s and SI_d (systolic and diastolic pressures, respectively), and calculated for mean and variability (standard deviation) in 24 h and two 12 h epochs (1–12 h and 13–24 h) after onset of symptoms. MBE was defined as neurological deterioration symptoms with imaging evidence of brain swelling. We employed a generalized estimating equation to compare the trend in longitudinal collected SI_s and SI_d between patients with and without MBE. We used multivariate logistic regression to investigate the correlation between SI_s, SI_d and outcomes. Results: Of the included 162 LHI patients, 28.4% (46/162) developed MBE and 25.3% (40/158) died within one month. SI_s and SI_d increased over baseline in all patients, with a similar ascending profile during the first 12 h epoch and a more intensive increase in the MBE group during the second 12 h epoch (p < 0.05). During the overall 24 h, patients with greater SI_d variability had a significantly increased MBE risk after adjustment (OR 3.72, 95%CI 1.38–10.04). Additionally, during the second 12 h epoch (13–24 h after symptom onset), patients developing MBE had a significantly higher SI_d level (OR 1.18, 95%CI 1.00–1.39) and greater SI_d variability (OR 3.16, 95%CI 1.35–7.40). Higher SI_d and greater SI_d variability within 24 h independently correlated with one-month death (all p < 0.05). Within the second 12 h epoch, higher SI_s, higher SI_d and greater SI_d variability independently correlated with one-month death (all p < 0.05). No significant correlation was observed in the first 12 h epoch. Conclusions: Higher and more fluctuated heart-rate-to-blood-pressure ratios independently correlated with MBE development and one-month death in LHI patients, especially during the second 12 h (13–24 h) epoch after onset. Full article