Search

This study combined numerical simulation and experiment to explore the influence of the concave‐wall jets with uniformly distributed tangential inlets in the cyclone separator on the liquid–solid separation characteristics and equipment. The results show that as the number of tangential inlets increases, the superposition effect of particle trajectories and flow fields becomes more significant. The superimposed flow field enhances the circumferential flow velocity of the fluid, causing the distribution of the jet along the radial and spanwise directions to shrink, greatly improving the uniformity of particle distribution and turbulent kinetic energy along the circumference, and effectively reducing the impact of particles on local areas near the jet inlet. Since the superposition of circumferential multi‐inlet jets enhances the swirling flow, the local disturbance and wall erosion effects near the jet inlet were reduced. Compared with double inlets, the flow rates of three inlets and four inlets were increased by 50% and 100%, respectively, the maximum turbulent kinetic energy increased by 14.5% and 56.2%, and the maximum escape time of particles was shortened by 3.2 and 3.3 s, respectively, the maximum erosion rates were reduced by 38.4% and 23.6%, respectively, and the separation efficiency and material handling capacity were significantly improved. This study supplemented the theory of concave‐wall jets' superposition characteristics and provided a theoretical basis for applying circumferential multi‐inlet devices in liquid–solid separation equipment. [ABSTRACT FROM AUTHOR]

The increasing prevalence of wearable devices has sparked a growing interest in real‐time health monitoring and physiological parameter tracking. This study focuses on the development of a cost‐effective sweat analysis device, utilizing microfluidic technology and selective electrochemical electrodes for non‐invasive monitoring of glucose and potassium ions. The device, through real‐time monitoring of glucose and potassium ion levels in sweat during physical activity, issues a warning signal when reaching experimentally set thresholds (K+ concentration at 7.5 mM, glucose concentrations at 60 μM and 120 μM). This alerts users to potential dehydration and hypoglycemic conditions. Through the integration of microfluidic devices and precise electrochemical analysis techniques, the device enables accurate and real‐time monitoring of glucose and potassium ions in sweat. This advancement in wearable technology holds significant potential for personalized health management and preventive care, promoting overall well‐being, and optimizing performance during physical activities. [ABSTRACT FROM AUTHOR]

Urine provides an ideal source for disease biomarker discovery. High-adhesion contaminants such as urobilin, which are difficult to remove from urine, can severely interfere with urinary proteomic analysis. Here, we aimed to establish a strategy based on single-pot, solid-phase-enhanced sample preparation (SP3) technology to prepare samples for urinary proteomics analysis that almost completely eliminates the impact of urobilin. A systematic evaluation of the effects of two urinary protein precipitation methods, two types of protein lysis buffers, and different ratios of magnetic digestion beads on the identification and quantification of the microscale urinary proteome was conducted. Our results indicate that methanol–chloroform precipitation, coupled with efficient lysis facilitated by urea, and subsequent enzymatic digestion using a mix of hydrophilic and hydrophobic magnetic beads offers the best performance. Further applying this strategy to the urine of patients with benign prostatic hyperplasia, prostate cancer and healthy individuals, combined with a narrow window of data-independent acquisition, FGFR4, MYLK, ORM2, GOLM1, SPP1, CD55, CSF1, DLD and TIMP3 were identified as potential biomarkers to discriminate benign prostatic hyperplasia and prostate cancer patients. [ABSTRACT FROM AUTHOR]

In this paper, to realize a better adaptive method for the lightning electric field signal denoising, we firstly compared the decomposition results of three methods called the EMD (empirical mode decomposition), the CEEMDAN (complete ensemble empirical mode decomposition with adaptive noise), and the EWT (empirical wavelet transform) by artificial signals, respectively, and found that the EWT was better than the other two methods. Then, a MEWT (modified empirical wavelet transform) method based on the EWT was presented for processing the natural lightning signals data. By using our MEWT method, we processed three types of electric field signal data with different frequency bands radiated by the lightning step leader, the cloud pulse and the return stroke, respectively, and the VLF (very low frequency) lightning signals propagating different distances from 500 km to 3500 km, by using the data of the fast electric field change sensors from Nanjing Lightning Location Network (NLLN) in 2018 and the data of the fast electric field change sensors and the VLF electric antennas from the NUIST Wide-range Lightning Location System (NWLLS) in 2021. The results showed that our presented MEWT method could adaptively process different lightning signal data with different frequencies from the step leader, the cloud pulse, and the return stroke; for the lightning VLF signal data from 500 km to 3500 km, the MEWT also achieved a better noise reduction effect. After denoising the signal by using our MEWT, the detection ability of the fast electric field change sensor was improved, and more weak lightning signals could be identified. [ABSTRACT FROM AUTHOR]

The effects of real terrain on the lightning magnetic fields and location accuracy are studied by using two-dimensional finite difference time-domain method. Two estimation methods of wave arrival time (using the time corresponding to the peak field and 10% threshold of the peak field) are applied to the arrival time delay, and then using the ToA technique with three approaches of arrival time differences to evaluate the location accuracy. It is found that the effect of real terrain on the lightning magnetic fields is due to the enhancement of reflection wave and propagation attenuation of terrain topography. The arrival time of peak value method is delayed from 0.15 to 2.3 μs, while that of 10% threshold method varied from −0.11 to 0.92 μs. The lightning location accuracy using the 10% threshold method is least, about tens of meters. Furthermore, considering the specific frequency bandwidth of detection sensors, three-order 10- to 500 kHz Butterworth filter was applied. After filtering, the effect of real terrain on the lightning magnetic fields becomes more obvious. The 10% threshold method is still the best way for lightning location, and the frequency bandwidth of different sensors on the effect of the location accuracy cannot be ignored. [ABSTRACT FROM AUTHOR]

In this article, we studied the propagation effect of finite ground conductivity and earth's curvature on the far vertical electric fields at ground level radiated by narrow bipolar events (NBEs), within several hundreds of kilometers from the discharge channel. Two different NBE current moments with risetimes of 5 and 8 μs are adopted, and two discharge heights of 5 and 15 km are considered, respectively. Simulation results show that the effect of earth's curvature should be considered when the propagation distance is larger than 200 km, and the propagation effect is closely related the NBE discharge current waveform, the discharge height, the ground conductivity, and the observation distance. With the decrease in ground conductivity, the field attenuation obviously increases. Besides, the attenuation is more when the source contains more high frequency component. It is also found that the propagation effect is more obvious when the discharge height is lower, especially for ground conductivity lower than 0.01 S/m. The reduction of NBE's far field peak caused by the propagation effect can reach about 42%, 60%, and 70% at the propagation distance of 100, 200, and 300 km, respectively. Furthermore, the current moment of NBE will be underestimated by about 5–35% from the observed far field without considering the propagation effect, within 300 km from NBE channel. However, the propagation effect on the estimation of NBE charge moment can be approximately ignored. [ABSTRACT FROM AUTHOR]

In this article, the effect of a mountain located on the propagation path of lightning-radiated electromagnetic fields was systematically studied by using the two-dimensional finite-difference time-domain method (2-D FDTD), considering the influence of the return stroke (RS) type, the ground conductivity, the mountain height and the width at the base, its position, and the observation distance. The field peak reduction and the wave arrival time delay, compared with those for the perfectly conducting flat ground, are analyzed in detail. The results show that, with an increase in the mountain height, the field peak reduces and the wave arrival time delay increases. The wave arrival time is insensitive to the change of mountain widths. The terrain envelope method can be used to estimate the additional time delay introduced by the mountain. For a mountain lower than 1 km or so, the additional attenuation effect of the mountain on the field peak can be ignored for most practical purposes. Furthermore, the propagation process of the lightning-radiated electromagnetic wave over the mountain was studied by analyzing the spatiotemporal evolution characteristics of the field. The analysis shows that the electromagnetic wave propagates to the back of the mountain through the diffraction process at the mountaintop. [ABSTRACT FROM AUTHOR]

Multiple‐stimuli responsive soft actuators with tunable initial shapes would have substantial potential in broad technological applications, ranging from advanced sensors, smart robots to biomedical devices. However, existing soft actuators are often limited to single initial shape and are unable to reversibly reconfigure into desirable shapes, which severely restricts the multifunctions that can be integrated into one actuator. Here, a novel reconfigurable supramolecular polymer/polyethylene terephthalate (PET) bilayer actuator exhibiting multiple‐stimuli responses is presented. In this bilayer actuator, the supramolecular polymer layer constructed of poly(5‐Norbornene‐2‐carboxylic acid‐1,3‐cyclooctadiene) (PNCCO) and azopyridine derivative (PyAzoPy) via H‐bonds provides multiple‐stimuli responses: PyAzoPy offers light response and carboxylic groups in PNCCO endow the actuator with humidity response. Meanwhile thermoplastic PET layer enables the bilayer actuators to be reconfigured into various shapes by thermal stimuli. The rationally designed actuators exhibit versatile capabilities to reversibly reconfigure into a set of initial shapes and carry out multiple functions, such as photo‐driven "foldback‐clip" and Ω‐shaped crawling robots. In addition, bio‐inspired plants constructed by reconfiguration of such actuators demonstrate reversible multiple‐stimuli responses. It is anticipated that these novel actuators with highly tunable geometries and actuation modes would be useful to develop multifunctional devices capable of performing diverse tasks. [ABSTRACT FROM AUTHOR]

This paper analyzes the effect of lightning strikes to an oblique cone-shaped mountain on the lightning-induced voltages on the power distribution line. The lightning-generated electromagnetic fields are calculated by using a three-dimensional finite-difference time-domain method in Cartesian coordinates, and the lightning-induced voltages are computed by means of Agrawal coupling model. The simulation results are presented for an oblique cone-shaped mountain with different inclining angles, and for different relative positions of the distribution line placed over nonflat lossy terrain. It is found that, when lightning strikes the top of an oblique cone-shaped mountain, the lightning-induced voltages are closely related with the mountain inclining angles where the distribution line is located above as well as the other mountain inclining angles; in general, the peak values of induced voltages increase with increasing inclining angles. For example, for the constant angle β = 45° (the inclining angle where the line is located above), the induced voltages at the close end of line for α = 26.6°, 45°, and 63.4° (the inclining angle opposite to angle β) is increased by 24%, 60%, and 106% as compared with that for flat ground, respectively. [ABSTRACT FROM AUTHOR]

This paper evaluates the lightning-induced voltages of two typical multiconductor lines configurations with or without shielding wires over lossy ground for striking the cone-shaped mountain top, by means of a cylindrical two-dimensional finite-difference time-domain method and Agrawal coupling model. It is found that the lightning-induced voltages both for the vertical and the horizontal configurations can be enhanced obviously for striking to the cone-shaped mountain, compared with the case of flat terrain, especially for the lower finite ground conductivity. The larger mountain inclining angle results in the higher peak values of lightning-induced voltages, which can be explained by the enhancement of lightning electromagnetic fields due to wave reflection of the transition between mountain terrain and flat ground. Moreover, the shielding wires can effectively reduce the voltages induced at both ends of the phase lines. [ABSTRACT FROM AUTHOR]

This paper presents the computed lightning-radiated vertical electric field and azimuthal magnetic field at the ground level at observing distances ranging from 0.3 to 50 km from the lightning channel for striking the cone-shaped mountain top, by using the two-dimensional finite-difference time-domain method in cylindrical coordinate systems. It is found that the mountain height and the inclination angle have a significant effect on the lightning-radiated electromagnetic field both for the close and far observing distances. For the lightning-radiated vertical electric field, the enhancement of the far field beyond several kilometers (mainly radiation field component) is due to the reflection process in the transition between the mountain terrain and the flat ground, but the reduction of close field near the mountain terrain (mainly quasi-electrostatic field component) is due to the shadowing effect, but not due to such reflection. For the lightning-radiated azimuthal magnetic field, the field values for different mountain terrains, including the mountain height and inclination angle, increase both for close and far observing distances. [ABSTRACT FROM AUTHOR]

A new approximate method for lightning-radiated extremely low-frequency (ELF) and very low-frequency (VLF) ground wave propagation over intermediate ranges is presented in this paper. In our approximate method, the original field attenuation function is divided into two factors in frequency domain representing the propagation effect of the ground conductivity and Earth’s curvature, and both of them have clearer formulations and can more easily be calculated rather than solving a complex differential equation related to Airy functions. The comparison results show that our new approximate method can predict the lightning-radiated field peak value over the intermediate range with a satisfactory accuracy within maximum errors of 0.0%, −3.3%, and −8.7% for the earth conductivity of 4 S/m, 0.01 S/m, and 0.001 S/m, respectively. We also find that Earth’s curvature has much more effect on the field propagation at the intermediate ranges than the finite ground conductivity, and the lightning-radiated ELF/VLF electric field peak value (V/m) at the intermediate ranges yields a propagation distance d (km) dependence of d−1.32. [ABSTRACT FROM AUTHOR]

The loss of natural shorelines has been accelerated by the construction of artificial shorelines in recent years, which is a serious threat to intertidal biodiversity and makes the ecological construction of artificial shorelines increasingly urgent, yet the mechanisms of regulating intertidal biodiversity using artificial structures are still poorly understood. In this study, the different fates and causes of the ecological effects of the two artificial seawalls were investigated in detail. We conducted on-site sampling and surveys on the water quality, wave conditions, and organisms around seawalls of different types of structures, and quantified the hydrodynamic strength distribution of the seawall walls through field experiments, while introducing numerical simulation methods to reproduce the flow field characteristics near the seawalls. The results show that the differences in the ecological effects of the investigated artificial seawalls are mainly due to flow (including wave-induced flow) rather than water quality, or other factors. Although the cavity structure of the seawall surface contributes to biodiversity, it is also the presence of this large and complex cavity structure that leads to local flow field heterogeneity in the seawall, which enhances fluid wall shear and makes it more difficult for intertidal organisms to attach and even causes a decrease in their surface biomass. However, in terms of ecosystem health, seawalls with more complex structures provide a more stable community structure, so we believe that they are more ecologically sound. In ecological shoreline construction, flow field heterogeneity should be taken into account as an important driver of biotic community assemblages on artificial coastlines. How to reconcile structural complexity with the resulting flow field heterogeneity should be an important part of ecological engineering construction. Our study provides new insights into the ecological construction of artificial shorelines. • An increase in fluid shear can lead to a decrease in biomass. • Biodiversity and biomass can be non-positively correlated. • Heterogeneity of the flow field leads to differences in ecological characteristics. • Flow field heterogeneity should be considered when building ecological seawalls. [ABSTRACT FROM AUTHOR]

In this paper, we have employed the 3-D finite-difference time-domain technique to analyze the influence of the vertically stratified conducting ground (mixed path) on the lightning-induced voltages of the overhead line at 60 and 200 m from the lightning strike point by using decomposing method. In order to analyze the effect range caused by mixed path, we assumed that the mixed path has much different conductivities with 100:1 ratio. When the conductivity near the strike point (0.1 S/m) is larger than that near the overhead line section (0.001 S/m), the induced voltage clearly increases with the increase of the closest distance from the center of the line to the interface between the two media (dl). However, for strike point with a less conducting earth (0.001 S/m) than the overhead line section (0.1 S/m), when dl is less than 30 m, the influence of the stratification should be considered; when dl is larger than 30 m, it can just be regarded as a homogeneous soil with the conductivity of 0.1 S/m equal to that near the overhead line. For the smaller ratio of conductivities of the mixed path, its effect on the induced voltages decreases. [ABSTRACT FROM AUTHOR]

In this paper we have studied the propagation effect of frequency-dependent soil (FDS) on the far vertical electric fields radiated by subsequent lightning strike to tall objects with heights from 50 to 300 m. It is found that the field propagation attenuation along FDS is obviously less than that case where the parameters are assumed to be constant (low-frequency conductivity at 100 Hz, LFC), and with the decrease of LFC, the corresponding field attenuation increases. When LFC is equal to or larger than 0.01 S/m, the effect of FDS can be ignored. However, when LFC is 0.0001 S/m, the field peak for FDS may reach as much as 2.5 times of that earth with LFC for strike to a 300-m-tall object. [ABSTRACT FROM PUBLISHER]

Based on the two-dimensional finite-difference time-domain (2-D FDTD) method, we have validated the time-domain method presented by Barbosa (B-P formula) for calculating the lightning-radiated horizontal electric field at the earth surface within distances from 30 to 1000 m from the lightning channel, considering the horizontally stratified earth. The results show that, except for distances in the vicinity of the lightning channel (e.g., 30 m), the B-P approximate formula can approximately predict the field peak value from 50 to 1000 m with a satisfactory accuracy within errors of 10% and its accuracy for subsequent return strokes seems to be more or less the same as that for first return strokes. The rise-time part of the field wave predicted by the B-P approximate formula is similar to that predicted by the 2-D FDTD, however, the tail of the wave predicted by the B-P approximation may be shorter than that by the 2-D FDTD (e.g., 30 and 50 m). [ABSTRACT FROM AUTHOR]

The impulse charge moment change (iCMC) is an important electrical property of cloud-to-ground (CG) lightning. In this paper, a new method of measuring the iCMC at distances of several hundred kilometers is proposed. The method is based on the vertical electric field below 1 kHz measured by the widely used fast electric field antenna with low frequency/very low frequency (LF/VLF) band. The impulse response of Earth-ionosphere waveguide (EIWG) is modeled using a finite difference time domain (FDTD) method considering an anisotropic ionosphere. By comparing the observed waveform with the simulated impulse response, the lightning discharge is classified into the impulsive discharge and the non-impulsive discharge. For the impulsive discharge, its iCMC is obtained directly by comparing the measured ELF waveform to the modeled impulse response at the same distance. For the non-impulsive discharge, its current moment waveform is assumed to be a sum of two Heidler's functions, and the genetic algorithm is used to search the unknown parameters in the functions. The good agreement between the measured ELF waveform and the simulated waveform implies that the extracted current moments are reasonable. This method can be used to continuously monitor the lightning iCMC in a given time and space. [ABSTRACT FROM AUTHOR]

The equivalent propagation method adopts a variable propagation velocity in lightning location, minimizing the location error caused by various factors in the long-range lightning location network. To verify the feasibility of this method, we establish a long-range lightning location network in China. A new method is used to extract the ground wave peak points of the lightning sferics and is combined with the equivalent propagation velocity method for lightning location. By comparing with the lightning data detected by the lightning locating system called advanced direction and time-of-arrival detecting (ADTD) that has been widely used for tens of years in China, the feasibility of this method is initially verified. Additionally, it is found that the relative detection efficiency of our long-range lightning location network can reach 53%, the average location error is 9.17 km, and the detection range can reach more than 3000 km. The equivalent propagation method can improve the average location accuracy by ~1.16 km, compared with the assumed light speed of lightning-radiated sferic from the lightning stroke point to the observation station. The 50th percentile of the equal propagation velocity is 0.998c, which may be used in the long-range lightning location networks. [ABSTRACT FROM AUTHOR]