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Numerical simulation technology is a crucial tool for reducing costs and increasing efficiency in the wind power industry. However, with the development of large-scale wind turbines, the computational cost of numerical simulation has gradually increased. This paper uses the geometric similarity, structural similarity criterion, Reynolds similarity and boundary layer theory to establish a scaled model of the geometric three-dimensional shape, composite material, and finite element mesh of large wind turbine blades. The study analyzes the aerodynamic, gravitational, and centrifugal load variations within the scaled model. The proportional relationship between the scaled model's operating parameters, the numerical simulation's environmental parameters, and the mechanical response parameters is established. These parameters are coordinated to ensure the similarity of the blade structure and the fluid dynamics. For a geometric scale factor of 0.316, the relative difference in maximum deflection is 4.52%, with a reduction in calculation time by 48.1%. On the premise of ensuring the calculation accuracy of the aerodynamic and structural response of the blade, the calculation efficiency is effectively improved. [ABSTRACT FROM AUTHOR]

Aims: Root respiration and its temperature sensitivity (Q10) are key parameters for understanding the processes and mechanisms of carbon cycling in forest ecosystems. However, the variation and influencing factors of root respiration rate and Q10 among soil depths have been poorly explored. Methods: We measured root respiration rates of the first five orders at 6, 18 and 24 °C, in surface (0–10 cm) and subsurface (20–30 cm) soil layers in six temperate tree species (Fraxinus mandshurica, Phellodendron amurense, Prunus padus, Larix gmelinii, Picea koraiensis and Pinus sylvestris var. mongolica) and calculated their Q10. Concurrently, we determined root morphological and chemical traits and soil properties. Results: Shallow roots generally exhibited faster respiration rates and higher Q10, which was more prominent in the first two order roots. Respiration rates of the first two orders measured at 18 °C were positively correlated with root diameter, root nitrogen concentration and ambient soil temperature (significant only for the first order), but negatively with root tissue density. By contrast, Q10 values were only significantly correlated with soil temperature on the day of root sampling. Furthermore, according to the conceptual framework of the root economics space, root traits along the "conservation" gradient were mainly affected by soil depth, with shallow roots showing "fast" respiration rates and high nitrogen concentrations. Conclusions: The systematic variation of root respiration and Q10 between soil depths and among root orders should be considered towards a mechanistic understanding of carbon cycling in forest ecosystems which would shed light on modeling the carbon cycle. [ABSTRACT FROM AUTHOR]

Root nitrogen (N)-uptake rate and uptake preference, and their association with root morphological and chemical traits are important to characterize root N-acquisition strategies of trees. However, how the root N-acquisition strategy varies with tree age, especially for those species that coexist at a common site, remains unknown. In this study, a field isotopic hydroponic method was used to determine the uptake rate and contribution of NH4+, NO3− and glycine, for three coexisting ectomycorrhizal coniferous species [ Pinus koraiensis (Korean pine), Picea koraiensis (Korean spruce) and Abies nephrolepis (smelly fir)] at three age classes (young, middle-aged and mature) in a temperate forest. Concurrently, root morphological and chemical traits, as well as mycorrhizal colonization rate were determined. Our results show that the root uptake rate of total N and NH4+ gradually decreased across all three species with increasing tree age. The three species at all age classes preferred NH4+, except for middle-aged Korean spruce and mature smelly fir, which preferred glycine. In contrast, all three species showed the lowest acquisition of NO3−. According to the conceptual framework of 'root economics space', only a 'collaboration' gradient (i.e. dimension of root diameter vs specific root length or area) was identified for each species, in which root N-uptake rate loaded heavily on the side of 'do-it-yourself' (i.e. foraging N more by roots). Young trees of all species tended to exhibit the 'do-it-yourself' strategy for N uptake, and mature trees had an 'outsourcing' strategy (i.e. foraging N by a mycorrhizal partner), whereas middle-aged trees showed a balanced strategy. These findings suggest that shifts of root N-acquisition strategy with tree age in these species are mainly mediated by root traits along the 'collaboration' gradient, which advances our understanding of belowground competition, species coexistence and N cycling in temperate forests. [ABSTRACT FROM AUTHOR]

As the unique power entrance, the pantograph–catenary plays a vital role in providing traction power for high-speed railways. Along with the operational velocity of trains constantly increasing, the poor contact between the contact wire and the pantograph strip happens frequently due to the "rigid point" existing on the contact wire, forming the "off-line" phenomenon. The off-line phenomenon is normally accompanied by the pantograph–catenary arc occurring, which seriously threatens the safety of the power supply for the high-speed train. Nowadays, as some railways have been built in remote places at high altitude, the motion characteristics of the pantograph–catenary arc under the sub-atmospheric pressure with strong airflow are extremely different from the case under normal pressure. Herein, a pantograph–catenary arc experimental platform is built for observing the evolutionary process of the arc under the sub-atmospheric pressure strong-airflow condition. The impact brought from different air pressures and airflows on the arc is analyzed, as the experimental results show that the pantograph–catenary arc has different motion characteristics when the arcing process is at different stages. To further explore the reason resulting in the varying motion characteristics of the arc, a multi-stress coupled force analysis model is established, with the consideration of the influence of air pressure, wind load, thermal buoyancy, air resistance, arc self-magnetism, etc. From the perspective of force acting on the arc, the arc formation mechanism at the development evolutionary stages is investigated under sub-atmospheric pressure strong-airflow conditions, which lays a theoretical foundation for effectively restraining the pantograph–catenary arc. [ABSTRACT FROM AUTHOR]

Cold atmospheric-pressure plasma is used widely for treating material surfaces and can be considered for modifying insulation paper (IP) to improve its surface performance. However, the mechanism for interaction between reactive oxygen species (ROS), which are the dominant components of such plasma, and IP is important for setting experimental parameter values but is difficult to observe experimentally. In this paper, reactive force field molecular simulation technology is used to study the mechanism for interaction between ROS (O atoms, OH radicals, and H2O2 molecules) and cellulose, which is the main component of IP. The results show that the ROS can abstract H atoms, and the H2O2 molecules can also abstract hydroxyl groups from a cellulose chain, resulting in changes to the cellulose chain structure, such as reductions of the hydroxyl groups and pyran rings and formations of aldehyde and vinyl groups. The three types of ROS exhibit different reactivities when reacting with the cellulose chain, and the difficulty of breaking different bonds therein also differs, which influences how the chemical groups change the cellulose chain. This study provides basic insight into the mechanism for interaction between ROS and IP at the atomic level as well as offering some guidance for practical experiments. [ABSTRACT FROM AUTHOR]

The influence of interface temperature on the damage characteristics of C–Cu contacts' interface plays a critical role in the current-carrying friction process which occurs between the contact pairs. In this paper, a method is proposed to adjust the interface temperature via settling an external heat source. The damage morphology and material transfer of C–Cu contacts are focused on when the range of interface temperature varies from the room temperature (25 °C) to 300 °C. Based on the experimental results, it can be found that high interface temperature can inhibit the surficial erosion of carbon materials, which tends to be obvious, especially along with the increment of current. Moreover, both the delamination wear of carbon surface and the copper-to-carbon transfer behavior decrease with the thermal surge of interface. This beneficial effect of interface temperature results in the reduction in friction coefficient by 14.3%, whereas the negative impacts brought from the high interface temperature are the surface cracking and the rapid recovery of wear rate of carbon materials, under high-current condition. [ABSTRACT FROM AUTHOR]

Objectives: Magnesium sulfate (MgSO4) is one of the most commonly used agents for the treatment and prophylaxis of eclampsia in patients with severe preeclampsia. However, there is no international consensus regarding the optimal gestational age for MgSO4 treatment. The aim of this study was to assess the effect of MgSO4 on uterine (UtA), umbilical, and fetal middle cerebral arteries (MCA) by calculating the SD ratio (S/D), resistance index (RI), and pulsatility index (PI) at different gestational weeks. Methods: In total, 66 pregnant women as participants with severe preeclampsia were divided into two groups based on gestational age: Group 1 (n = 28, 26–30 weeks) and Group 2 (n = 38, 30–34 weeks). Color Doppler (Philip HD11) measurements were taken and compared before and after the MgSO4 loading dose. Results: Within-group analysis revealed significant differences in RI-UtA, PI-UtA, and S/D in UtA before and after MgSO4 administration in Group 1. Furthermore, the RI-UA and RI-MCA decreased statistically significantly after MgSO4 treatment, whereas the pulsatility index and S/D did not change in either the umbilical or middle cerebral arteries. After MgSO4 treatment, all Doppler parameters in the uterine and umbilical arteries in Group 2 showed significant changes when compared to before MgSO4 administration. Conclusion: MgSO4 can effectively improve umbilical and MCA blood flow at 30–34 gestational weeks but not at 26–30w. Meanwhile, using MgSO4 can improve uterine blood flow in severe preeclampsia, which may contribute to the management of reducing adverse events in pregnant women who have preeclampsia and fetal growth restriction. [ABSTRACT FROM AUTHOR]

The mycorrhizal growth response (MGR), defined as the biomass difference between a mycorrhizal plant and a non-mycorrhizal plant of the same species, varies with soil nutrient availability, fungal taxa, and host plant functional group. However, how MGR reacts to changes in arbuscular mycorrhizal fungus (AMF) richness is still not well understood. To assess how AMF richness affected MGR in different organs of plants and discover how MGR varied with plant functional groups, we collected 72 published papers that concurrently studied single and mixed inocula treatments in two common plant functional groups: woody and herbaceous plants. We then compiled a dataset of mycorrhizal colonization rate (MC), MGR of root biomass (MGRr), MGR of shoot biomass (MGRs), MGR of total biomass (MGRt), and root-to-shoot ratio (MGRr/s) for single, dual, and multiple inocula at the fungus and plant species levels. Variation of MGR parameters and MC along inoculum richness generally showed similar patterns at the fungus and plant species levels in both woody and herbaceous plants, respectively. MC tended to increase from single to multiple inocula in the two plant functional groups. MGRs, MGRr, and MGRt tended to increase with increasing inoculum richness in woody plants, but not in herbaceous plants, with nearly 2-fold increments between single and multiple inocula. MGRr/s was generally stable in both woody and herbaceous plants. In general, MC and MGR parameters, except for MGRr/s, were higher in woody plants than in herbaceous plants with the same inoculum richness. The strong positive effect of inoculum richness on MGR parameters in woody plants can be explained by the close relationships between MGR and MC, and between MGR and inoculum richness. Conversely, in herbaceous plants, the associations were weak between MGR parameters and MC or inoculum richness. Our results suggest that multiple inocula generally had a stronger positive impact on MGR parameters than single and dual inocula, and this effect was more prominent in woody plants than in herbaceous plants. These findings not only deepen the understanding of the interaction between AMF richness and host plant growth but also provide insights into the application and development of AMF fertilizer in agriculture and forestry. [Display omitted] ● Multiple inocula generally have a stronger positive impact on MGR parameters. ● Effects of multiple inocula is more prominent in woody plants than in herbs. ● Species and family richness of AMF is the key to the strength of inoculum effect. [ABSTRACT FROM AUTHOR]

• The law of the different air gap defects with different lengths in cable terminal for high-speed trains was studied. • By using the method of high frequency pulse current to measure the prefabricated air gap defect cable terminal, the development of internal defects in cable terminals can be divided into three stages. • A novel monitoring system for the internal defect detection of cable terminal was proposed based on electric field strength. • The novel method can be used to assist in judging the development state of the internal air gap defect of cable terminal in high-speed trains. It is vital that accurately and effectively detecting the insulation status of cable terminal to ensure the safe and stable operation of high-speed trains. Accordingly, a novel monitoring system for the internal defect detection of cable terminal was proposed based on electric field strength. Firstly, partial discharge and electric field strength along the surface of the air gap defects cable terminal umbrella skirt were measured and analyzed. The development of internal defects in cable terminals can be divided into three stages: S 1 , S 2 , and S 3. Then, the interquartile range, variance, average value and dispersion coefficient of electric field strength have been proposed to characterize the development state of air gap defects in cable terminal. The results shows that the internal defects of cable terminals develop from 20% l to 100% l , the slope of the interquartile range of the distribution of magnitudes of the electric field intensity increases from 0.126 to 0.671, and the absolute value of variance and offset increase by about 81.3% and 80.66%, respectively. Therefore, it is feasible and effective to detect the development state of air gap defects inside the cable terminal by measuring and analyzing the electric field strength characteristics along the surface of the cable terminal umbrella skirt. [ABSTRACT FROM AUTHOR]

Aims: Absorptive and transport roots (diameter ≤ 2 mm) are closely related to soil resource uptake for plant growth, carbon budget and nutrient cycling in forest ecosystems, but how and why the relative share of root biomass or root length for both root functional types changes with tree species is not well understood. Our aims were to examine the inter-specific variations of root biomass and length per unit area of absorptive and transport roots, and their relationships with stand structure and soil characteristics, root morphological and architectural traits. Methods: We measured root biomass and length per unit area, diameter, specific root length (SRL), root tissue density (RTD), and branching ratio of the first five order roots, stand and soil characteristics in seven forests consisting of different tree species at a common site. The first order roots were classified as absorptive roots and the other orders as transport roots based on our earlier work. Results: Biomass ratios of absorptive to transport roots varied from 1:5.56 to 1:1.12 among species, and length ratios ranged from 1:1.56 to 1:0.29. Root biomass was not influenced by root morphology or architecture, nor by stand or soil characteristics. Absorptive root length was significantly correlated with SRL, RTD, and branching ratio of the first to second order roots among species, whereas transport root length was significantly correlated with stem density. Conclusions: The relative share of biomass and length for absorptive and transport roots differed among tree species, which may influence belowground carbon allocation and resource competition. [ABSTRACT FROM AUTHOR]

Currently, the detection equipment for offline arcing on high-speed trains is of great interest because it can evacuate the contact state between the contact wire and the strip. In order to ensure the safety of the train under the effect of the arcing, the self-designed fourth-order Hilbert curve fractal antenna is chosen to detect the arcing, in this paper, based on its electromagnetic radiation signal. Aspects of time-, frequency-, and joint time–frequency-domain analyses of the signals were considered. Meanwhile, the experiments were conducted several times with different circuit currents and different electrode gaps, and the electromagnetic pulses under different moments were studied. Results indicated that the electromagnetic radiation pulses were corresponding to the abrupt variations of voltage during arcing, and all the characteristic frequencies were located at similar values (18 MHz). Mechanisms of using the short-time Fourier transform method to obtain an accurate arcing moment, extinguished time, and arcing duration have been explained in detail. Thus, the characteristics of arcing electromagnetic radiation could become the significant and efficient parameters to detect the pantograph–catenary operation state of high-speed trains. [ABSTRACT FROM AUTHOR]

With the development of the Internet, the Internet applications represented by Peer-to-Peer (P2P) streaming systems bring more and more communication overhead. In order to alleviate communication pressure of the Internet, and improve the user's access experience, we aim at taking full advantage of peer upload bandwidth contributions with a cache on each peer. While, the size of such a cache on each peer is limited, it is necessary to design the cache replacement strategy in such P2P Systems. In this paper, we implemented a collaborative caching mechanism for P2P streaming networks. Firstly, we designed some measurement experiments for the existing large-scale P2P streaming systems to find some features and problems. Then, we proposed the collaborative caching strategy based on the chunk value and requesting distribution factor to address the existing problems. Our goal is to keep those chunks with high requesting frequency and farther away from the current peer in order to achieve higher cache hit rate and load balancing. Compare to the measured P2P streaming systems, the simulation results show that the proposed method has better performance on multiple metrics such as cache hits, system load and peer collaboration. [ABSTRACT FROM AUTHOR]

• WT-CNN effectively identifies PD in cable termination of high-speed train. • No need to manually extract features to achieve high-precision recognition. • Improved signal recognition accuracy of CNN by WT noise reduction. The cable termination is an important part of the energy transmission of high-speed trains and is also a weak link in the insulation. It is important to determine the insulation status of the cable termination by the state of the partial discharge signal, but the partial discharge signal in the field test circuit is mixed with a large amount of external corona interference, which affects the detection accuracy. This paper proposes a wavelet transform and convolutional neural networks (WT-CNN) based classification model for the accurate and fast identification of corona disturbances in the partial discharge signals of cable termination for high-speed train. The method uses wavelet transform noise reduction and adaptive moment estimation (Adam) as the optimizer. The effect of WT on the classification effect of CNN is analyzed, and it is shown that the method can still achieve over 94% accuracy with small training samples. [ABSTRACT FROM AUTHOR]

• The faulty cable of the high-speed electric multiple units (EMU) is dissected and the cause of the fault is analysed. • The internal defects of the cable terminal aggravate the electric field distortion, which is easy to cause partial discharge. • The influence law of the typical defect size and position of the EMU cable terminal on the electric field strength is studied. • When installing cable termination, pay attention to the treatment of three-phase junctions from the main insulation, outer semiconducting point layer and stress tube. • It is necessary to find a suitable cable termination electric field optimization scheme. High voltage cable terminal of high-speed electric multiple units (EMU) is an important part of on-board high voltage equipment. As the weak link of the cable assembly, the cable terminal is prone to penetrability discharge and resulting in insulation failure, which seriously affects the EMU's safety and reliability. The electric field intensity distribution of high-voltage cable terminal with internal defects such as air gaps, moisture, semiconductors and carbons are simulated and studied. At the same time, in order to improve the distortion of the internal electric field intensity of the EMU cable terminal, nonlinear materials and high dielectric materials are used to replace the stress tube respectively, and the optimization effects of the two materials on the internal distortion electric field of the cable terminal are studied. The results show that the defects are closer to the multi-layer combination area among main insulation layer, stress tube layer and outer semiconducting layer of the cable terminal, the electric field distortion of multi-layer combination area become greater. With the increasing of defect size, the electric field intensity also gradually increases. However, the inner defect location and size have less effect on the electric field intensity along the cable terminal umbrella skirt. It is found that both nonlinear materials and high dielectric materials can effectively optimize the electric field intensity of cable terminal and improve the electric field distortion. This work can be helpful for operation and design of high-speed EMU's cable terminal. [ABSTRACT FROM AUTHOR]

The relationship between partition function, particle density, refractive index, and temperature for atmospheric plasma is calculated based on thermodynamics and chemical equilibrium. Taking into account the contribution of hydrogen-like levels to the atomic partition function, a compact method to calculate the atomic partition function is first used with the Eindhoven model to deduce the plasma's refractive index. Results calculated by the new approach and two other traditional simplified methods are compared and analyzed. For a better understanding on the temperature measurement accuracy deduced by different partition function disposal approaches, moiré deflectometry is employed as the experimental scheme to acquire the refractive index-position curve. Finally, applicability of different partition function disposal approaches are discussed, and results indicate that the optical properties deduced in this paper are well suited for the refractive index–based plasma diagnosis. [ABSTRACT FROM AUTHOR]

Under long-term synergy effect of multi-factors, especially the thermal stress, insulating paper will be degraded and its insulation performance will decline due to carbonization and degradation of cellulose. This paper presents an optical approach for aging feature extraction of the insulating paper, where one of the image processing methods called texture analysis is utilized. By conducting laboratory accelerated thermal aging tests, insulating paper samples with different aging conditions for both Nomex and Kraft, evaluated with the aging time, are prepared. After taking optical microscopic images of insulating paper samples belong to different aging groups, up to 14 texture features are extracted using the gray-level co-occurrence matrix (GLCM). With different feature selection methods applied, several of them are finally selected to represent the aging condition of insulating. Numerical tests with both supervised and unsupervised algorithms, as well as a linear regression method verifies the validity of these features in characterizing the aging condition of the insulating paper. [ABSTRACT FROM PUBLISHER]

Grafting nanomaterials on the carbon fiber (CF) surface is considered an effective strategy for enhancing the interfacial properties of CF-reinforced polymer composites (CFRPs). However, the mechanical properties of the CFs are often compromised during treatment. A new method for in situ growing silver nanoparticles (AgNPs) on the CF surface is proposed in this study. The CFs are first immersed in a low-viscosity silver nitrate solution to form a thin liquid film on the surface. Subsequently, using the abundant active particles in the plasma, the silver ions are reduced to silver atoms and grown into AgNPs on the CF surface. The tensile strength of CF@Ag was 38.74% greater than that of untreated CF, potentially due to the reparative action of AgNPs on defects in CF. The CF showed an evident improvement in surface wettability because of the AgNPs. Furthermore, the interfacial properties were noticeably improved, with the interfacial shear strength of CF@Ag increasing to 91.59 MPa, which was about twice that of pristine CF. Thus, the mechanical properties of composites are significantly improved (flexural strength increased by 190.74%). This study presents a non-destructive and convenient method for growing nanoparticles onto CF to establish a robust interface in CFRPs. [ABSTRACT FROM AUTHOR]

Pantograph–catenary (PC) arc has become an obstacle for the further development of high-speed railway. Understanding on the underlying physical mechanisms of PC arc dynamics is still far away from satisfactory; therefore, researches from both experimental and numerical aspects are urgently required. This paper focused on the dynamic characteristics of PC arc during the pantograph lowering process by numerical simulation method. A PC arc model was established based on the classical magnetohydrodynamics theory, with the temporal evolution of PC arc dynamics considered. The dynamic mesh technique was utilized to take care of the departure process between the pantograph and the catenary. Detailed behaviors of arc plasmas during the pantograph lowering process were presented by the temperature distribution and flow filed. Two interesting vortexes located below the catenary were found. The vortexes rotated in the opposite direction, resulting from the special gas flow motion during the pantograph movement. Furthermore, the gas flow brought about a thermal pinch effect on arc column, which had a significant influence on the next behaviors of arc plasmas. Besides, the effects of input current on the arc characteristics were studied. [ABSTRACT FROM AUTHOR]

Failure mechanism due to corona aging and characteristics of PD (partial discharge) on nano doped PI (polyimide) film are investigated under bipolar impulse voltage. Chemical characterization of material is analyzed through SEM (scanning electron microscope) and FTIR (Fourier transform infrared spectroscopy). The results show that failure of specimens is mainly caused by surface discharge which could be suppressed by the addition of nano particles. The Al2O3 nano fillers improved the corona resistant property of PI film significantly. The corona resistant lifetime of PI/Al2O3 sample is six times longer than that of pure PI. Furthermore, to know the frequency and rise time effect of surface discharge on specimens, mean discharge quantity of PD under impulse voltage is measured. Increase of pulse frequency leads to enhancement of PD activity, whereas increase of rise time, weakens PD activity. The discovered effects of profound significance will help on improving dielectric properties of nanocomposites towards various applications. [ABSTRACT FROM AUTHOR]

This paper presents an alternative reanalysis algorithm based on the block matrix to address problems with local modifications. In this method, the modified stiffness can be classified as three parts: influenced region, stationary region and an interface region between them. The main computation cost concentrates on the influenced region by this specific blocked strategy. Compared with popular reanalysis methods, the proposed method can achieve an accurate response for large modification with lower computation cost. Several practical engineering problems are analyzed and the results are exactly as that performed by full analysis. [ABSTRACT FROM AUTHOR]

High-speed airflow, which is generated around trains running at a high speed, causes uneven pollutant distribution on insulator surfaces and changes their insulation properties. In this paper, a method has been proposed to calculate the residual pollutant resistance on polluted insulator. Based on the analysis of flashover model, the influence of pollution distribution along and around insulator was discussed. Analysis result showed that flashover voltage would increase when the pollutant distribution on insulator decreased compared to conditions with uniformly distributed pollutant, and vice versa. It implied that there should be a maximum pollutant accumulation value above and below the insulator shed. In this situation, the flashover voltage will be the lowest. Model analysis showed that the flashover voltage would increase with the length of the insulated plate and vice versa. The theoretical analysis was in good agreement with experimental result, which implied that this method might be able to provide reference for insulator shed design. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel distributed caching algorithms in unstructured peer-to-peer file sharing networks. [•] A distance-based network infrastructure with preference-based three-way random walk. [•] Probability-based and greedy-based caching placement and replacement algorithms. [•] Compromising and balancing the resources allocated for objects with different popularity to remedy the over-caching problem. [ABSTRACT FROM AUTHOR]

Originally used as the default infrastructure for efficient file sharing, peer-to-peer (P2P) architecture achieved great successes. Now, the P2P model has been adopted for many other distributed applications, such as instant message and phone services, Internet gaming, and large-scale scientific computing. In recent years, P2P streaming systems experienced tremendous growth and became one of the largest bandwidth consumers on the Internet. Compared to standard file sharing systems, the streaming services show unique characteristics with more stringent time constraints and require much higher network bandwidth. It is extremely important to evaluate and analyze existing applications, and investigate the merits and weaknesses in these systems for future development. In this paper, we conduct a comprehensive measurement study on two of the most popular P2P streaming systems, namely, PPLive and PPStream. They are very popular P2P streaming applications, and serving millions of registered users with hundreds of live TV channels and millions of other video clips. In our measurement, we deploy our collectors in China, and both live TV and video-on-demand (VoD) channels are evaluated. We record run-time network traffic on the client side, compare and analyze the characteristics of these channels based on their popularity. For both categories, we perceive that, in general, the two measured P2P streaming systems provide satisfactory experience to the audiences for all channels regardless of popularity. However, the most of data are downloaded from the dedicated servers for unpopular channels. We also observe that live TV channels show better peer coordination than VoD channels. Beside the traffic, we have also collected cache replacement information for VoD channels, and these measurement results can help us understand the caching mechanism of P2P streaming systems. With the support of the cache, VoD channels perform better than their counterparts in the live TV category in terms of data transmission, workload distribution, and signal traffic overhead. Overall, our results reveal that although P2P streaming systems can usually provide excellent viewing experience for popular channels, there are still challenges to fully support unpopular channels. New designs and algorithms are in urgent need, especially for unpopular live TV channels. [ABSTRACT FROM AUTHOR]

The popular dynamic reanalysis methods, such as combined approximation (CA) mainly focus on frequency domain. Compared with time domain analysis, the main challenge for reanalysis methods is to calculate the responses in each iteration. Due to this difficulty, popular reanalysis methods are not available for time domain analysis, such as Newmark- $\beta $ and central different method (CDF). Therefore, a novel adaptive time-based global reanalysis (ATGR) algorithm for Newmark- $\beta $ method is suggested. If basis vectors are generated for predicting the response in each time step, computational cost of reanalysis should be significantly increased. To improve the efficiency, an adaptive reanalysis algorithm is suggested. Moreover, in order to enhance the accuracy of the popular combined algorithm (CA) reanalysis, a global strategy is suggested to construct basis vectors. Numerical examples show that accurate approximations are achieved efficiently for time domain problems. [ABSTRACT FROM AUTHOR]

The high-speed railway (HSR) has become more important in modern society. However, the rail potential rises remarkably, because of the high leakage resistance to earth with the use of ballastless track and huge traction return current on rail. That is a serious threat to passengers' and equipment safety along the railway. Integrated grounding line (IGL) can decrease rail potential obviously. Its structure is quite different from grounding rods in non-HSR substations. Meanwhile, IGL goes along the entire railway, and its parameters' optimization can obtain enormous economic benefits and significantly decrease the workload of laying the line. Therefore, the performance of IGL should be studied in detail. With assessment of grounding impedance and shunting coefficient, the relationships between IGL parameters and its performance have been analyzed. Related experiments had also been carried out on the SUI-YU railway (the first ballastless HSR in China). Compared with the theoretical results, the differences were less than 15% and 5% for grounding impedance and shunting coefficient, respectively. With the analyzing results, some pieces of advice have been proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The C C bonds are the initial decomposition positions of C 6 F 12 O. • Main radicals (CF 3 , CF 2 , CF, F, C and O) and main small molecules (CF 4 , CO and COF 2) are different in distributions and sources. • Pressure (0.1–0.5 MPa) can influence the distributions of radicals and small molecules significantly. Thermal decomposition mechanisms and product distributions of C 6 F 12 O (perfluoro (2-methyl-3-pentanone)) are studied by reactive force field molecular dynamics (ReaxFF-MD) and density functional theory (DFT). C 6 F 12 O decomposes from C C bonds because they have lower reaction energies than C O and C F bonds. Endothermic and exothermic reactions exist in the decomposition process of C 6 F 12 O. The decomposition products are radicals and small molecules. Distributions of main radicals (like CF 3 , CF 2 , CF, F, C and O radicals) and main small molecules (CF 4 , CO and COF 2 molecules) can be influenced by pressure. This study provides new insights for C 6 F 12 O application in two phase immersion cooling transformer. [ABSTRACT FROM AUTHOR]

The durability issue is the primary factor affecting the life and cost of Polymer Electrolyte Membrane Fuel Cell (PEMFC). This paper presents a novel State of health (SOH) prognosis method for PEMFC in different conditions using Principal Component Analysis (PCA) and Gaussian Process Regression (GPR). Firstly, the robust locally weighted smoothing method is used to preprocess the recorded PEMFC operation data for filtering measurement errors. Then, PCA is applied to extract the principal components of the time series of original multi-dimensional input variables for PEMFC, eliminating the correlation between the original variables and reducing the dimensionality of input variables. Finally, the degradation prognosis and Remaining Useful Life (RUL) prognosis are made by GPR. Two degradation experiments for PEMFC verify the proposed method in different conditions. The test result shows that PCA can effectively reduce the dimensionality of PEMFC operating conditions. Compared with traditional methods, PCA-GPR has higher SOH prognosis accuracy. PCA-GPR provides a 462-h RUL prognosis on a life duration of 1150 h, which is sufficient for maintaining the PEMFC. • PEMFC operating variables are reconstructed by the principal component analysis. • PEMFC degradation prognosis model is established by Gaussian process regression. • The proposed method provides a higher degradation prognosis accuracy for PEMFC. • Proposed method makes a long remaining useful life prognosis for PEMFC. [ABSTRACT FROM AUTHOR]

Cable termination is an important part of energy transmission in high-speed trains, and it is also a weak link in the insulation. It is important to determine the insulation status of cable terminals by the detection results of partial discharge signals, but the partial discharge signals in the field test circuit are mixed with a large amount of external corona interference, which affects the detection accuracy. This paper proposes a signal recognition model that incorporates Stockwell transform (ST) and 2DCNN, which in combination with wavelet noise reduction can achieve a high-precision classification effect for partial discharge and corona interference with an accuracy rate of up to 98.75%. By selecting the maximum energy moment in the ST matrix to correct the position of the time window during the recognition of long time series signals, the problem of corona interference being truncated by the time window and being misidentified as partial discharge is overcome, and the generalization ability of the model is enhanced. Experimental results show that the method has an excellent performance in separating partial discharge and corona interference in long time series signals. [ABSTRACT FROM AUTHOR]

Superior performance fillers are considered as an effective means to enhance the performance of carbon/graphite composites. However, poor interfacial properties and incomplete filler networks limit the performance enhancement of the composites. In this study, a new method was proposed to weaken this impact through the synergistic effect of the electrostatic self-assembly of nano carbon black (NCB) onto carbon nanotubes (CNTs). The results showed that the synergistic effect between NCB and the CNTs significantly improved the mechanical and electrical properties of the composites. NCB reduces the porosity of the composites and increases the interaction between the CNTs and matrix. The compressive strength of the composite was 143.2 Mpa, and the flexural strength was 46.3 MPa, which is 210% higher than that of the pristine carbon/graphite composites. Moreover, NCB and CNTs form a globally connected synergistic network in the carbon skeleton. Composites filled with CNTs/NCB exhibited the lowest resistivity and highest thermal conductivity, with a resistance that was 42% lower than that of pristine carbon/graphite composites at 44.8 μΩ m. All of these results suggest that the synergistic effect of CNTs/NCB show great potential to improve the performance of carbon/graphite composites. [Display omitted] • NCB was self-assembled with CNTs by electrostatic force, forming an enhanced phase with synergistic effect. • Targeted improvement of matrix properties near CNTs using NCB can enhance the interfacial properties. • Self-assembly of CNTs with NCB forms a synergistic network in the composite to enhance electrical and thermal properties. [ABSTRACT FROM AUTHOR]

Finite element numerical progressive damage modelling and simulations applied to the strength prediction of airframe bolted joints on composite laminates can lead to shorter and more efficient product cycles in terms of design, analysis and certification, while benefiting the economic manufacturing of composite structures. In the study herein, experimental bolted joint bearing tests were carried out to study the strength and failure modes of fastened composite plates under static tensile loads. The experimental results were subsequently benchmarked against various progressive damage numerical modelling simulations where the effects of different failure criteria, damage variables and subroutines were considered. Evidence was produced that indicated that both the accuracy of the simulation results and the speed of calculation were affected by the choice of user input and numerical scheme. [ABSTRACT FROM AUTHOR]

The study aimed to analyze the developmental mode of auditory at the level of brainstem in preschool autistic children using click-evoked auditory brainstem response (click-ABR). Methods : Twenty children with autism spectrum disorder (ASD) and 20 age matched typical development children (TD) were recruited. The detail data recorded from click-ABR were collected at two time periods (T1 and T2). There was no significant change in TD group at two time periods. In ASD group, wave V latency was significantly shortened at T2 compared to that recorded at T1. The interpeak latency of I–V was short at T2 versus at T1 in the autistic children. Compared to the TD group, ASD was associated with longer latencies for waves V and longer interpeak latencies of I-III, I–V at T1. In addition, ASD group also indicated longer latencies of wave III and wave V, longer interpeak latencies of I-III and I–V at T2 compared to the TD group. ASD group had immature and dysfunction developmental mode in auditory stimuli perception at the level of brainstem. The performance of auditory ability in children with ASD improved gradually with ages. However, there are still differences compared with TD children. [ABSTRACT FROM AUTHOR]

• Elevated [CO 2 ] significantly modify leaf morphology, anatomy and physiology. • Absorptive roots become thicker under elevated [CO 2 ], accompanied with greater cortex. • Functional traits of leaf and root coordinately respond to elevated [CO 2 ]. • Trait-responses to elevated [CO 2 ] are more sensitive in woody than herbaceous plants. Elevated atmospheric CO 2 concentration (e[CO 2 ]) profoundly affects the growth and physiological activities of plants. However, the responses of leaf and root functional traits to e[CO 2 ] are rarely investigated together, limiting our understanding of the whole-plant adaptive strategies to climate change. In this study, 17 temperate woody (nine) and herbaceous (eight) plant species were grown under ambient [CO 2 ] (a[CO 2 ], 380 ppm) and e[CO 2 ] (720 ppm) conditions in the chamber (Percival Scientific, Perry, USA), and the responses of 16 key functional traits (anatomy, morphology, physiology) of leaves and typical absorptive roots (the 1st order root) and their relationships were studied. Averagely, we found that e[CO 2 ] increased leaf thickness (LT, +13 %), reduced specific leaf area (SLA, -14 %), increased palisade tissue thickness (PT, +23 %) and the ratio of palisade tissue to spongy tissue thickness (P/S, +14 %) across species, which were accompanied by physiological changes. For absorptive root, root diameter (RD) increased by 15 %, specific root length (SRL) decreased by 12 %, and root tissue density (RTD) decreased by 14 % across species under e[CO 2 ], indicating that plants tend to construct thicker roots with looser tissue under e[CO 2 ] compared to a[CO 2 ]. Also root cortical thickness (CT) and the ratio of cortical thickness to stele radius (C/S) increased by 20 % and 13 % under e[CO 2 ], respectively, implying an increase in root potential absorption capacity. More importantly, the corresponding functional traits of leaf and absorptive root, i.e., LT and RD, SLA and SRL, PT and CT, P/S and C/S, showed positive correlations in their magnitudes of the responses to e[CO 2 ] in both woody and herbaceous species. Our study revealed the coordinated changes of corresponding functional traits in leaf and absorptive root under e[CO 2 ] condition, which provide some insights into the whole-plant resources acquisition strategy under changing environment. [ABSTRACT FROM AUTHOR]

Lithium–ion batteries are key elements of electric vehicles and energy storage systems, and their accurate State of Charge (SOC) estimation is momentous for battery energy management, safe operation, and extended service life. In this paper, the Multi-Kernel Relevance Vector Machine (MKRVM) and Whale Optimization Algorithm (WOA) are used to estimate the SOC of lithium–ion batteries under different operating conditions. In order to better learn and estimate the battery SOC, MKRVM is used to establish a model to estimate lithium–ion battery SOC. WOA is used to automatically adjust and optimize weights and kernel parameters of MKRVM to improve estimation accuracy. The proposed model is validated with three lithium–ion batteries under different operating conditions. In contrast to other optimization algorithms, WOA has a better optimization effect and can estimate the SOC more accurately. In contrast to the single kernel function, the proposed multi-kernel function greatly improves the precision of the SOC estimation model. In contrast to the traditional method, the WOA-MKRVM has a higher precision of SOC estimation. [ABSTRACT FROM AUTHOR]

Purpose: Mifepristone in conjunction with misoprostol, is widely used in China as an effective medical abortifacient. However, a small proportion of women experience the unpleasant side effects of prolonged vaginal bleeding caused by delayed embryo expulsion. The aims of this study were to determine whether the expression levels of prostanoid receptors in human decidua are associated with delayed embryo expulsion in mifepristone-misoprostol induced an early medical abortion.Methods: Discharged decidua tissues were collected from females undergoing an artificial abortion (AA) (n = 28), females with early embryo expulsion during a medical abortion (EEMA) (n = 20) and delayed embryo expulsion in medical abortion (DEMA) (n = 30). The expression levels of prostanoid receptors in human decidua were assessed with immunohistochemistry and real-time PCR methods. Further, the RNAi method was used to silence prostanoid receptors 4 (EP4) in the primary decidual cells and human endometrial adenocarcinoma cell line Ishikawa cells in vitro and cell cycle analysis of these cells was performed.Results: All five prostanoid receptors (EP1-4, FP) were observed in human early pregnancy decidua. The protein and mRNA expression level of EP4 in the DEMA group were all significantly higher than that in the EEMA group. EP4 silence induced G1/S arrest of primary decidual cells and Ishikawa cells in vitro.Conclusions: Elevated expression level of EP4 in human decidua was significantly associated with delayed embryo expulsion in early medical abortion by promoting decidual cell proliferation. Detailed studies on the nature of roles EP4 plays in human decidua will help us to develop more effective prevention and noninvasive intervention approaches for delayed embryo expulsion during a medical abortion. [ABSTRACT FROM AUTHOR]

Partial discharge detection is considered a crucial technique for evaluating insulation performance and identifying defect types in cable terminals of high-speed electric multiple units (EMUs). In this study, terminal samples exhibiting four typical defects were prepared from high-speed EMUs. A cable discharge testing system, utilizing high-frequency current sensing, was developed to collect discharge signals, and datasets corresponding to these defects were established. This study proposes the use of the convolutional neural network (CNN) for the classification of discharge signals associated with specific defects, comparing this method with two existing neural network (NN)-based classification models that employ the back-propagation NN and the radial basis function NN, respectively. The comparative results demonstrate that the CNN-based model excels in accurately identifying signals from various defect types in the cable terminals of high-speed EMUs, surpassing the two existing NN-based classification models. [ABSTRACT FROM AUTHOR]

Thermal defects widely occur in electrical equipment and affect its stable operation. This paper proposes a novel detection method based on derivatives for thermal defects of electrical equipment. First, the equivalent models of the equipment are established to analyze the surface temperature formed by different defects. Second, the theoretical foundation of the derivative-based detection method is described, and numerical calculations on thermal defect detection based on derivative characteristic curves are carried out. The results show that the method can detect the position effectively and calculate the depth with an error of 1.6%. Then, the thermal defects in different situations are analyzed, and the results indicate that the method is effective in all cases. Finally, the experiment is conducted by artificially preparing samples with thermal defects, and the achieved calculation error of the experimental results is within 3.3%, which indicates the validity of this method. [ABSTRACT FROM AUTHOR]

Currently, great attention has been paid to the fast development of high-speed railways all over the world. With an increment of running speed, pantograph arcing has become a significant issue, which can threaten the lifespan and service performance of pantograph strip materials severely. Cu-impregnated carbon strip is one of the most widely used strip materials in high-speed railways, while its arc erosion characteristics and mechanisms are still in absence. In this paper, the arc erosion characteristics of Cu-impregnated carbon materials were experimentally studied. The variations in voltage waveforms between electrodes with time were recorded, and the evolution of the temperature distribution of strip was obtained by a thermal infrared imager. The arc erosion surface was examined using a digital camera, a scanning electron microscopy, and energy dispersive X-ray spectroscopy to assess the macroscopic and microscopic morphologies, as well as elemental distributions in or around the arc erosion crater. An interesting arc crater-centered multicolored subarea on the strip surface was found, which was explained from the aspects of the effect of arc-induced temperature and formation of copper oxide film. The arc erosion crater consisted of several overlapped erosion pits, and the mechanism of the pits was understood from the unique microstructure and physical properties of carbon phase and copper phase in the materials. Finally, the formation of spherical copper particles and cracks was illustrated, and their influences on the sliding wear and friction process were discussed. [ABSTRACT FROM AUTHOR]

Wheat yellow mosaic is a soil-borne virus disease, and now has become one of the main viral diseases endangering wheat production in China, posing serious threat to wheat production. The pathogen, transmission media, incidence regularity and performance of wheat yellow mosaic were introduced in the paper, and its molecular biology and breeding research were summarized, in order to provide a reference for resistance breeding and production practice of wheat yellow mosaic. [ABSTRACT FROM AUTHOR]

Background: Non-regional lymph node (NRLN) metastases has shown increasing importance in the prognosis evaluation and clinical management of primary metastatic hormone-sensitive prostate cancer (mHSPC). Hence, this study aimed to investigate the concordance rates between 18F-PSMA-1007 PET/CT and conventional imaging (CI) in revealing NRLN metastases, and explore the impact of NRLN metastases on the management of primary mHSPC. Methods: The medical records of 224 patients with primary mHSPC were retrospectively reviewed, including 101 patients (45.1%) only received CI for TNM classification, 24 patients (10.7%) only received 18F-PSMA-1007 PET/CT, and 99 patients (44.2%) received both 18F-PSMA-1007 PET/CT and CI. Among patients who received 18F-PSMA-1007 PET/CT and CI before initial treatment, the concordance rates between 18F-PSMA-1007 PET/CT and CI were analyzed. The high-volume disease was defined as the presence of visceral metastases and/or ≥ 4 bone metastases (≥ 1 beyond the vertebral bodies or the pelvis) based on the findings of 18F-PSMA-1007 PET/CT and/or CI. The primary endpoint was progression-free survival (PFS), and Cox regression analyses were performed to explore independent predictors of PFS. Results: A total of 99 patients (44.2%) received both 18F-PSMA-1007 PET/CT and CI, the concordance rate in revealing NRLN metastases between 18F-PSMA-1007 PET/CT and CI was only 61.62%, and Cohen's kappa coefficient was as low as 0.092. Moreover, 18F-PSMA-1007 PET/CT detected an additional 37 of 94 (39.4%) patients with positive NRLNs who were negative on CI. Cox regression revealed that androgen deprivation therapy (ADT), N1, high-volume, NRLN and visceral metastases were associated with worse PFS (all P < 0.05) in 224 patients. Furthermore, in patients with low-volume disease, the median PFS of patients with NRLN metastases was significantly shorter than that of patients without NRLN metastases (19.5 vs. 27.5 months, P = 0.01), while the difference between patients with low-volume plus NRLN metastases and high-volume disease was not significant (19.5 vs. 16.9 months, P = 0.55). Moreover, early docetaxel chemotherapy significantly prolonged the PFS of these patients compared with ADT alone (20.7 vs. 12.3 months, P = 0.008). Conclusion: NRLN metastases could be accurately revealed by 18F-PSMA-1007 PET/CT, which should be considered a high-volume feature, especially concomitant with bone metastases. Furthermore, patients with low-volume plus NRLN metastases may be suitable for more intensive treatment, such as early docetaxel chemotherapy. [ABSTRACT FROM AUTHOR]

The grounding electrode line is an important part of the Ultra high voltage direct current (UHVDC) transmission system. It acts as the channel to conduct the unbalanced current and the grounding current.The arcing horn consists of a pair of electrodes installed in parallel at both ends of the insulator string, which provides a discharge channel for the fault current by an air gap to protect the insulators. In this paper, the voltage and current distributions of the arcing horn were studied when the grounding electrode line was struck by lightning. It is found that the current and voltage gradually decrease along the direction from the converter station to the earth electrode. An active arc extinguishing method based on variable resistance for arcing horn was proposed. An electromagnetic transient simulation model of the grounding electrode line is established based on the electrical parameters of a ±800 kV UHVDC transmission system. It is found that the absorbed energy of the arc extinguishing unit needs to be at least 31.2 and 49.6 kJ when the lightning current is 20 and 50kA, respectively. According to the calculation results, the arcing horn with arc extinguishing unit was developed and tested. The test results verifies that the designed arcing horn can meet the requirements of engineering application. [ABSTRACT FROM AUTHOR]

Phenomena of the pantograph arcing have become a challenge for the further development of high-speed electrified railway system. Despite of the large attention that has been paid to the radiated electromagnetic interference, materials ablation as well as the power-quality decline resulted from pantograph arcing, the specific dynamics of pantograph arcing with a high time resolution are still in absence. In this paper, the pantograph arcing phenomena in a laboratory simulation system were experimentally studied by high-speed photography. Synchronized electrical voltage and current waveforms were obtained to acquire a more comprehensive understanding on the underlying physics. The overall dynamics of the pantograph arcing from ignition to extinguishment were recorded. Three stages of the electric-contact process, from approaching arc, mechanical contact to the drawn arc, were well distinguished. A much intensified drawn arc was observed than the approaching arc. Typical lasting time of the drawn arcing is found $\sim 4$ times larger than the approaching arcing for our test setup. Maximum diameter of 3.3 mm was reached at around the current-peak moment. An interesting stable arc voltage of \sim 23$ V was found during the drawn arcing. Intense material splash above the carbon strip was observed during the arcing process. The transient resistance during a typical arcing period was also analyzed, and a minimum value of \sim 100~\text{m}\Omega was determined. [ABSTRACT FROM PUBLISHER]

Human chorionic villous mesenchymal stem cells (CV‐MSCs) are a promising and effective therapeutic option for tissue injury. Vascular dysfunction during pregnancies is significantly involved in the pathogenesis of preeclampsia (PE). This work aims to investigate how CV‐MSCs regulate the function of vascular endothelial cells. In this study, RNA‐seq analysis was used to examine the changes in HUVECs treated with CV‐MSC conditioned medium (CM). We examined the levels of ABCA9 and AKT signaling in human umbilical vein endothelial cells (HUVECs) by immunohistochemistry, western blotting, and qRT‐PCR assays. CCK‐8, colony formation, and tube formation assays were used to understand the role of ABCA9 in HUVEC proliferation and angiogenesis mediated by CV‐MSCs. The CV‐MSC treatment significantly enhanced the HUVEC proliferation and angiogenesis. Furthermore, a significant increase in the ABCA9 expression and AKT pathway activation was observed in CV‐MSCs ‐treated HUVECs. Consistent with these findings, ABCA9 overexpression exhibited the same proliferation‐and angiogenesis‐promoting effect in HUVECs as induced by CV‐MSC CM, also accompanied the AKT signaling activation. In addition, inhibition of ABCA9 inactivated the AKT signaling in HUVECs and reduced the HUVEC proliferation and angiogenesis. Importantly, the elevation of proliferation and angiogenesis induced by ABCA9 overexpression in HUVECs could be reversed by AKT pathway inhibition. Our results suggest that ABCA9‐dependent AKT signaling activation mediated by CV‐MSCs could promote HUVEC proliferation and angiogenesis. [ABSTRACT FROM AUTHOR]

Acidic environments are a significant factor in the aging and failure of silicone rubber insulators. Addressing the effective assessment of insulators' aging state to prevent power transmission accidents has been a critical and urgent issue for the power grid. Therefore, hyperspectral imaging (HSI) technology was employed in this paper, capturing spectral line data of silicone rubber in six aging states in both visible and near-infrared regions, respectively. To reduce data redundancy, genetic algorithm (GA) and band weighting were introduced to improve traditional principal component analysis (PCA), with performance compared using overall accuracy (OA) and Kappa, against 12 other feature extraction or dimensionality reduction methods. The improved principal component analysis − support vector machine (IPCA-SVM) model proposed effectively minimizes irrelevant information in hyperspectral original data, exceeding 93% accuracy and improving OA by 8.26% compared to all bands data. Finally, the IPCA-SVM model was used for pixel-level assessment of the surface aging state of silicone rubber insulators, demonstrating its reliability. This method effectively characterizes the aging state of composite insulators, providing a solid foundation for the safe and stable operation of power grids. [ABSTRACT FROM AUTHOR]

The sliding electrical contact is the only means by which high-speed trains obtain energy. When icing occurs on the contact lines, the impact vibrations of the pantograph-catenary system are further exacerbated, electrical arcing becomes more frequent, and abnormal wear is caused, seriously threatening the safety of the energy supply for high-speed railways. To address the unclear mechanisms, unpredictable patterns, and challenging characterization of contact lines icing, this paper proposes a dynamic simulation method for the first time. Furthermore, a surrogate model for predicting contact line icing is developed using deep learning algorithms. First, based on grid updating, flow field analysis, and icing calculations, key icing parameters are obtained to establish a numerical model of contact lines icing under time-varying meteorological parameters. Then, the effects of factors such as wind speed, temperature, and liquid water content on the dynamic evolution characteristics of contact line icing are analyzed. Finally, using the CNN-GRU algorithm, a prediction model for contact line icing is constructed to predict the icing mass and contours. This research clarifies the evolution patterns of contact lines icing, addresses challenges in monitoring and predicting icing states, and lays a theoretical foundation for high-speed railways' safe and stable operation under icing conditions. • The dynamic evolution process of contact line icing is simulated using numerical calculation methods. • Clarified the growth patterns of the icing boundary under different environmental factors. • A sector-based partitioning method is proposed to achieve quantitative tracking of the contact line's icing contour. • A surrogate model for early prediction of catenary icing is established using deep learning algorithms. [ABSTRACT FROM AUTHOR]

In this paper, a surface discharge test was conducted on a silicone rubber insulating sheet, an epoxy resin insulating sheet, a porcelain insulating sheet, and a glass insulating sheet by using an independently constructed test platform of insulating media to study the discharge characteristics along the surface of insulating media under low air pressure and strong airflow environment. Experiments were conducted to obtain the variation in the discharge characteristics along the surface of the four kinds of insulation media with respect to airflow velocity at different air pressures. The discharge voltage characteristics and discharge morphology characteristics along the surface of the insulating media in a strong airflow environment at low air pressure are elucidated. This paper provides theoretical support for the selection of insulation materials and insulation protection design for a low air pressure and strong airflow environment. [ABSTRACT FROM AUTHOR]

Abstract: Thief zones are those laterally continuous stratigraphic units of relatively high permeability, which come into being in the reservoir after long-term waterflooding. Injected water circulates inefficiently in reservoirs with thief zones so that the development of these reservoirs is seriously weakened in high water cut stage. Viewed as a two-layer infinite homogeneous reservoir saturated by slightly compressible fluid, a well test interpretation model is presented. Then the pressure response at the observation well is obtained by superposition principle. Finally a new approach to identifying permeability and net thickness of thief zones is established based on semilog method. The methodology has been applied to Shengtuo Oilfield, which confirms that the proposed approach can be efficiently used to identify thief zones, providing parameters of thief zones for treatment project design. [ABSTRACT FROM AUTHOR]

Abstract: Vibrational IR spectra for the 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) have been calculated at density functional B3LYP level using the 6-31G(d) basis set. The effects of isotopic species to the spectra are discussed. The characteristic band at 3322.5 and 3220.9cm−1 is interpreted as the asymmetrical and symmetrical N–H stretching band, respectively. The band at 1571.3 and 1235.6cm−1 is attributed to the asymmetrical and symmetrical N–O stretching band, respectively. The bands at 1613.1 and 779.56cm−1 are attributed to the C–N stretch for the amino groups. The band at 1321.5cm−1 is attributed to the C–N′ stretch for the nitro groups. Three bands at 1448.4, 1181.2, and 1031.4cm−1 are assigned to the skeletal stretching modes of the aromatic ring. Three predicted very weak bands at 932.54, 539.32, and 741.48cm−1 are found without counterparts in the experimental spectrum. [Copyright &y& Elsevier]

The gas–solid interface of high-voltage insulating equipment is a weaker part of insulating equipment insulation, and preventing the occurrence of discharge along the surface of insulating equipment is a critical problem for high-voltage insulation. This article investigates the discharge characteristics and charge movement characteristics of insulating media under an airflow environment. The surface discharge characteristics of the insulating medium in the airflow environment were obtained by using a high-velocity airflow test platform, and the surface discharge voltage characteristics, discharge path characteristics, and force conditions of the discharge process were analyzed. The surface charge motion characteristics of the insulating medium in the high-velocity airflow environment were also tested, and the distribution characteristics, dissipation characteristics and conduction mechanism of the surface charge of the insulating medium in the high-velocity airflow environment were revealed. The research results showed that: the discharge voltage along the insulating medium surface gradually increases with the increasing velocity of airflow; the discharge path along the surface of the insulating medium gradually shifts backward under the action of airflow; under the action of airflow, the charge on the insulating medium surface is blown away, thus reducing the charge concentration on the insulating medium surface; the trap level center of the insulating medium gradually decreases under the action of airflow, which provides the conditions for the charge blowing effect on the insulating medium surface. This investigation supplies the theory support for the protection of insulation equipment in an airflow environment and technical guidance for the insulation design of insulating equipment in an airflow environment to ensure the secure and steady running of insulating equipment in high-speed trains and high-voltage transmission lines. [ABSTRACT FROM AUTHOR]

Carbon-carbon composites are widely used in thermal management, photocatalysis, aerospace, high-speed railway, and nuclear energy applications, owing to their low density, high temperature stability, corrosion resistance, and excellent self-lubrication performance. Improving the weak combination interface of carbon-carbon composites has always been challenging. Prior to the present study, there was no effective method for stimulating the interaction between the reinforcing phase and the carbon matrix. In this study, pre-oxidized carbon fibers with abundant active functional groups were introduced into ultrafine carbon powder, for significantly improving interfacial structural integrity in carbon-carbon composites. The effects of pre-oxidized carbon fiber on the composites were systematically studied using metallographic microscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy methods. The results show that chemical bonds are formed between pre-oxidized carbon fibers and the carbon matrix, increasing the interfacial bonding strength. The pre-oxidized carbon fibers expanded adaptively after sintering, with the diameter increasing by 19.47%. The fiber expansion process inhibited cracks, decreasing the composites' porosity by 21.6%. Compared with carbon fibers, the pre-oxidized carbon fibers improved the flexural strength, impact resistance, electrical conductivity, and thermal conductivity by 31.8%, 53.3%, 18.58%, and 14.06%, respectively. [ABSTRACT FROM AUTHOR]

Preeclampsia (PE), a pregnancy disorder that affects 5–7% of pregnant women, is among the primary causes for maternal and perinatal mortality. PE is believed to be associated with insufficient invasion of villous and extravillous trophoblasts (EVTs), which hampers uterine spiral artery remodeling and finally induces PE. But the mechanism responsible for reduction of trophoblast invasion remains unclear. In this study, placental tissues taken from healthy donors and PE patients were used to evaluate the miR-326 expression; CCK8 and colony formation assays were used to confirm the effect of miR-326 on cell proliferation; transwell assay was used to demonstrate the effect of miR-326 on cell invasion capability; western blot was used to investigate the underlying mechanism; and luciferase assay was used to detect the effect of miR-326 on YAP/TAZ-mediated transcription activity. It was revealed the miR-326 expression was higher in placentas from PE patients than from healthy donors. After transfection of miR-326 mimics, trophoblast proliferation and invasion were impaired. Using TargetScan, we speculated that PAX8 was a target of miR-326, which was later confirmed by western blot. The YAP/TAZ expression was also downregulated after transfection with miR-326. Luciferase assay demonstrated that overexpression of miR-326 suppressed YAP/TAZ-mediated transcription activity by targeting PAX8. Overexpression of PAX8 could partly rescue miR-326-induced suppression of trophoblast proliferation and invasion. Taken together, our result indicated that miR-326 suppresses trophoblast growth, invasion, and migration by means of targeting PAX8 via the Hippo pathway. [ABSTRACT FROM AUTHOR]