Search

Passenger thermal comfort in high-speed train (HST) carriages presents unique challenges due to factors such as extensive operational areas, longer travel durations, larger spaces, and higher passenger capacities. This study aims to propose a new prediction model to better understand and address thermal comfort in HST carriages. The proposed prediction model incorporates skin wettedness, vertical skin temperature difference (ΔTd), and skin temperature as parameters to predict the thermal sensation vote (TSV) of HST passengers. The experiments were conducted with 65 subjects, evenly distributed throughout the HST compartment. Thermal environmental conditions and physiological signals were measured to capture the subjects' thermal responses. The study also investigated regional and overall thermal sensations experienced by the subjects. Results revealed significant regional differences in skin temperature between upper and lower body parts. By analyzing data from 45 subjects, We analyzed the effect of 25 variables on TSV by partial least squares (PLS), from which we singled out 3 key factors. And the optimal multiple regression equation was derived to predict the TSV of HST occupants. Validation with an additional 20 subjects demonstrated a strong linear correlation (0.965) between the actual TSV and the predicted values, confirming the feasibility and accuracy of the developed prediction model. By integrating skin wettedness and ΔTd with skin temperature, the model provides a comprehensive approach to predicting thermal comfort in HST environments. This research contributes to advancing thermal comfort analysis in HST and offers valuable insights for optimizing HST system design and operation to meet passengers' comfort requirements. [ABSTRACT FROM AUTHOR]

As a supersonic transportation system, the flow around a vehicle in an Evacuated Tube Transportation (ETT) system will evolve through series of flow structures during acceleration. The occurrence of choked flow and shock wave will especially lead to the drastic change in flow field structures. In this study, based on the one-dimensional inviscid flow assumption, a theoretical model is established to quantitatively describe the formation time, formation location of choked flow, and Frontal Normal Shock Wave (FNSW), as well as the distance of the disturbed flow field region ahead of the vehicle in the ETT system. It is found out that the formation time of FNSW as well as the initial distance between the vehicle head and FNSW is linearly proportional to the blockage ratio while linearly inverse proportional to the acceleration rate of the vehicle. An experimentally verified numerical model is also established with an overset mesh technique to investigate the flow field evolution for vehicles accelerating in the ETT system. The results from numerical analysis agree well with the theoretical model. Meanwhile, five typical flow field structures are summarized for a vehicle accelerating from a stationary state to supersonic state in the ETT system. The applicability of the wind tunnel method and overset mesh technique in numerical simulation of the ETT system is systematically discussed. The influence of occurrence and dissipation of choked flow and shock wave on the vehicle's aerodynamic drag profile are then analyzed quantitatively. [ABSTRACT FROM AUTHOR]

Exfoliation process, PANI modification, and utilization of Et4N·BF4 electrolyte help construct a superior BCN-PANI-based supercapacitor device with a wide working voltage that is 3 times that of a pure PANI device. [Display omitted] • Efficient exfoliation improves the electrochemical performance. • PANI modification effectively boosts the capacitive reaction. • BCN help increase the voltage widow 3 times that of PANI device in Et 4 N·BF 4 electrolyte. Boron carbonitrides (BCN) have been widely concerned in the field of energy storage and conversion. However, the energy storage mechanism of electrical double-layer behavior and their stacked-layer structure severely limit the improvement of capacitance, thereby hindering their further development in energy storage. Therefore, an ultrasonic-ball milling method was first chosen to obtain BCN nanosheets, together with a feasible way of polyaniline (PANI) modification performed to boost the capacitive reaction of BCN nanosheets. For the first time, a BCN-PANI-based symmetric supercapacitor device can reach a high voltage window of 3.0 V when 1 M Et 4 N·BF 4 was chosen as the electrolyte. The working voltage of 3.0 V is three times that of a device with pure PANI with the ultrahigh energy density of 67.1 W h kg−1, superior to most of the reported PANI-based devices. The eminent electrochemical performance provides a promising strategy to pave the way for configuring carbon-based multiple composite electrodes for other energy storage devices. [ABSTRACT FROM AUTHOR]

To investigate the mechanism of Silent information regulator 1 (SIRT1) regulation of DNA methylation and thus the expression of synaptic plasticity-related genes induced by lead (Pb) exposure, the early-life Sprague-Dawley rats and PC12 cells were used to establish Pb exposure models and treated with SIRT1 agonists (resveratrol and SRT1720). In vivo results demonstrated that Pb exposure increased the expression of DNMTs, MeCP2, PP1 and cleaved caspase3, decreased the expression of SIRT1, BDNF and RELIN and altered DNA methylation levels of synaptic plasticity genes. Moreover, we observed marked pathological damage in the hippocampal CA1 region of the 0.2 % Pb-exposure group. After treatment with resveratrol, the effects of Pb exposure on the expression of the above molecules and pathological features were significantly ameliorated in the hippocampus of rats. In vitro results showed that after the treatment with SRT1720, the expression of SIRT1 was activated and thus reversed the effect on DNMTs, MeCP2, apoptosis and synaptic plasticity-related genes and their DNA methylation levels induced by Pb exposure. In conclusion, we validated the important protective role of SIRT1 in neurotoxicity induced by Pb exposure through in vivo and in vitro experiments, providing potential therapeutic targets for the treatment and prevention of brain damage. [Display omitted] [ABSTRACT FROM AUTHOR]

Purpose: Thoracic ossification of the ligamentum flavum (OLF) is an uncommon disease that mostly occurs in East Asians. Laminectomy is often considered when patients develop neuro-related symptoms but may associate with treatment-related complications. This study aimed to evaluate the efficacy and safety of unilateral biportal endoscopic (UBE) decompression treatment in patients with symptomatic OLF.Methods: From January 2020 to January 2021, patients with spinal cord compression symptoms and imaging-defined single-level thoracic OLF were enrolled in this study and received UBE decompression treatment. Their pre- and postoperative neurological statuses were evaluated by the modified Japanese Orthopaedic Association (mJOA) score, Visual Analog Scale (VAS) for leg pain, and Frankel grade.Results: Fourteen patients with an average age of 59.4 years were enrolled in the study. The mean operation time was 66.1 ± 15.4 minutes. Patients were followed up for at least one year after receiving the treatment. Our data suggested that their mJOA score (preop 6.2 ± 1.2, 1 year 8.5 ± 0.9; P < 0.001) and VAS score (preop 4.5 ± 2.0, 1 year 0.5 ± 0.9; P < 0.001) were significantly improved compared with that before operation. Cerebrospinal fluid leakage occurred in one patient, head and neck pain occurred in two patients, and hyperalgesia of lower limbs occurred in two patients. All these complications did not cause serious consequences.Conclusion: This primary study indicated that the UBE decompression treatment can achieve satisfactory clinical results in patients with thoracic OLF at single level and provide an alternative treatment option. [ABSTRACT FROM AUTHOR]

[Display omitted] • A machine-learning model is constructed based on experimental data to predicate the gas-sensing performance of oxides. • Six important features are proposed as the descriptors for gas sensing of oxides. • The active sites on oxides for gas sensing are described as ionic oxygen loosely bonded to metal atoms. Machine learning, a new research paradigm, is promising for device design, material discovery, and theoretical exploration, overcoming the drawbacks of experimental approaches. In this study, we used machine learning to explore the gas-sensing reactions of metal oxides. The training data were experimental results. Three types of features — metal oxide and gas molecule properties and operating conditions — were extracted as inputs for the machine learning algorithms. The genetic algorithm-adjusted artificial neural network achieved the best performance, and the neural network test was performed using two new experimental datasets. Further, Shapley Additive exPlanations were employed to understand the findings and explore key descriptors for gas sensing. The feature importance was ranked, and the first six features were selected as key descriptors for gas sensing using metal oxides. Furthermore, theoretical investigations were conducted, and the correlations between features and outcomes were analyzed. We found that the active site for gas sensing on pristine metal oxides comprises ionic oxygen loosely bonded to the metal sites. This study provides an example of the use of machine learning for material discovery. We expect that this study will encourage more studies on machine learning for gas sensing. [ABSTRACT FROM AUTHOR]

The relatively low operating voltage window is the main factor limiting the energy density of aqueous energy storage devices. The delicate design of heterostructured electrode materials can efficiently increase the intrinsic electrochemical performance through synergistic effects. For the first time, to broaden the voltage window of aqueous supercapacitors the synergistic effect between boroncarbonitrides (BCN) and built‐in electric field existing in heterostructures is designed to utilize. Based on this design concept, MnO/MnS@BCN electrode materials are synthesized, in which the synergistic effect can effectively strengthen the storage of electrolyte ions on the electrode surface, thus inhibiting the electrolysis of H2O and eventually broadening the voltage window of aqueous supercapacitor. In MnO/MnS@BCN‐based symmetrical supercapacitors, the voltage window of the device is extended from 1.2 V (single‐component) to 2 V, with the energy density enhanced to 75.0 W h kg−1. The strategy blazes an efficient and convenient path to broaden the intrinsic voltage window of transition metal oxide supercapacitors. [ABSTRACT FROM AUTHOR]

The relatively low operating voltage window is the main factor limiting the energy density of aqueous energy storage devices. The delicate design of heterostructured electrode materials can efficiently increase the intrinsic electrochemical performance through synergistic effects. For the first time, to broaden the voltage window of aqueous supercapacitors the synergistic effect between boroncarbonitrides (BCN) and built‐in electric field existing in heterostructures is designed to utilize. Based on this design concept, MnO/MnS@BCN electrode materials are synthesized, in which the synergistic effect can effectively strengthen the storage of electrolyte ions on the electrode surface, thus inhibiting the electrolysis of H2O and eventually broadening the voltage window of aqueous supercapacitor. In MnO/MnS@BCN‐based symmetrical supercapacitors, the voltage window of the device is extended from 1.2 V (single‐component) to 2 V, with the energy density enhanced to 75.0 W h kg−1. The strategy blazes an efficient and convenient path to broaden the intrinsic voltage window of transition metal oxide supercapacitors. [ABSTRACT FROM AUTHOR]

Of great importance is modeling for transducer design and application to predict its performance and simulate key characteristics. The equivalent circuit modeling (ECM), one of the most powerful tools, has been widely used in the transducer industry and academia due to its outstanding merits of low simulation cost and easy usage for multi-field simulation in both time and frequency domains. Nevertheless, most of the existing equivalent circuit models for Terfenol-D transducers normally ignore three material losses, namely elastic loss, piezomagnetic loss, and magnetic loss. Additionally, the magnetic leakage due to the intrinsic poor magnetic permeability of Terfenol-D is rarely considered into the piezomagnetic coupling. Both loss effects will produce substantial errors. Therefore, an improved SPICE model for a high-power Terfenol-D transducer considering the aforementioned three losses and magnetic flux leakage (MFL) is proposed in this article, which is implemented on the platform of LTspice software. To verify the usefulness and effectiveness of the proposed technique, a high-power Terfenol-D tonpilz transducer prototype with a resonance frequency of around 1 kHz and a maximum transmitting current response (TCR) of 187.1 dB/1A/ $\mu $ Pa is built and tested. The experimental results, both in the air and water of the transducer, are in excellent agreement with the simulated results, which well validates our proposed modeling methods. [ABSTRACT FROM AUTHOR]

• The underbody flow field of a representative 4-car formation subway is investigated. • Underbody flow regulation is realized through deflector installation. • The maximum temperatures of linear induction motors are reduced. • Influence of deflected flow on underbody flow field and device cooling is analyzed. The low-speed flow, restricted tunnel environment, and degraded motors have resulted in a serious challenge in the underbody equipment of subway trains, where overheating of multiple longitudinally aligned linear induction motors is one of the most urgent challenges to be resolved. In the face of this problem, the flow field distribution of a 4-car formation subway train is investigated. Two deflector installation designs are proposed to regulate the underbody flow using the passive flow control method to enhance the heat dissipation of motors. The influence of deflector installation is analyzed through an experimentally verified conjugated heat transfer numerical method. The results showed that the installation of deflectors can significantly enhance the longitudinal underbody flow. On the one hand, the deflector can effectively enhance the momentum exchange between underbody flow and the surrounding undisturbed flow field. On the other hand, the deflectors can break the large lateral vortices, such that the flow resistance along the longitudinal direction is reduced. Besides, the deflectors can also reduce the size of the wake behind the motor. As a result, the increased incoming flow rate ahead of motors effectively alleviated the overheating issue. The enhancement of heat transfer between different deflector installation designs was compared. It was found that the vertical edge of deflectors should be installed as close to the lateral edge of the subway car as possible. The maximum temperature of motors has been reduced by 9 % according to the installation design proposed in this study. The outcomes of this study can also provide theoretical guidance as well as engineering solutions for the cooling design of bottom heat sources and other similar overheating devices in thousands of railway trains with exposed underbody compartment. The convection enhancement around the heating devices can be realized by the surrounding flow field regulation method proposed in this study. [ABSTRACT FROM AUTHOR]

Heating, Ventilation, and Air Conditioning (HVAC) systems in high-speed trains (HST) are responsible for consuming approximately 70% of non-operational energy sources, yet they frequently fail to ensure provide adequate thermal comfort for the majority of passengers. Recent advancements in portable wearable sensors have opened up new possibilities for real-time detection of occupant thermal comfort status and timely feedback to the HVAC system. However, since occupant thermal comfort is subjective and cannot be directly measured, it is generally inferred from thermal environment parameters or physiological signals of occupants within the HST compartment. This paper presents a field test conducted to assess the thermal comfort of occupants within HST compartments. Leveraging physiological signals, including skin temperature, galvanic skin reaction, heart rate, and ambient temperature, we propose a Predicted Thermal Comfort (PTC) model for HST cabin occupants and establish an intelligent regulation model for the HVAC system. Nine input factors, comprising physiological signals, individual physiological characteristics, compartment seating, and ambient temperature, were formulated for the PTS model. In order to obtain an efficient and accurate PTC prediction model for HST cabin occupants, we compared the accuracy of different subsets of features trained by Machine Learning (ML) models of Random Forest, Decision Tree, Vector Machine and K-neighbourhood. We divided all the predicted feature values into four subsets, and did hyperparameter optimisation for each ML model. The HST compartment occupant PTC prediction model trained by Random Forest model obtained 90.4% Accuracy (F1 macro = 0.889). Subsequent sensitivity analyses of the best predictive models were then performed using SHapley Additive explanation (SHAP) and data-based sensitivity analysis (DSA) methods. The development of a more accurate and operationally efficient thermal comfort prediction model for HST occupants allows for precise and detailed feedback to the HVAC system. Consequently, the HVAC system can make the most appropriate and effective air supply adjustments, leading to improved satisfaction rates for HST occupant thermal comfort and the avoidance of energy wastage caused by inaccurate and untimely predictive feedback. • This paper presents thermal comfort model for high-speed train passengers based on skin temperature, galvanic skin response and electrocardiogram. • Differences in physiological signals and thermal sensation votes among different populations (Gender, BMI and position) were analyzed. • The features of the four combinations were used as input factors to obtain accuracy using different machine learning models. • Sensitivity analysis of the best prediction model (Random Forest) was performed using SHAP and DSA methods. [ABSTRACT FROM AUTHOR]

In high-speed train operations, especially during the passage of two trains or when passing through tunnels, the surface of the train experiences intense transient alternating pressure. The resulting alternating aerodynamic loads can lead to fatigue damage in the train's structure. To address this issue, an experimental device is developed in this study to accurately replicate the alternating aerodynamic loads experienced by trains. In this research, a novel method for simulating variable loads using triangular pressure wave patterns is proposed. Validation tests are conducted to assess the effectiveness of the device in replicating the desired load profiles. Furthermore, a noise suppression mechanism is incorporated into the device design. By incorporating noise source analysis and optimization techniques, the device design effectively controls the noise level within 85 dBA during the loading process. The experimental results demonstrate that the proposed device can achieve a triangular wave loading frequency of 2.5 cycles per minute, with a pressure range of ±3000 Pa for a 250 m3 high-speed train cabin. The pressure load output stability has high consistency in the pressure‒time curves at various measurement points inside the tested object, with a maximum difference of 0.99%. The experimental device designed in this study meets the requirements for simulating the aerodynamic loads on the surface of high-speed trains travelling at speeds of up to 350 km/h. • Novel device accurately simulates aerodynamic alternating loads on high-speed trains. • Integrated mechanism maintains noise levels below 85 dBA during loading. • Achieves stable triangular wave loading, crucial for replicating aerodynamic stresses on train cabin.. [ABSTRACT FROM AUTHOR]

Cartesian meshes based on the immersed boundary method are widely adopted for their convenience in implementing automated mesh generation. The performance of Cartesian mesh generation, particularly for complex geometries, is a crucial factor that directly impacts the efficiency of computational fluid dynamics solutions. In this study, we present an innovative strategy for efficient Cartesian mesh generation. Our methodology centers around the inner product test (IPT), enabling precise and efficient interior/exterior determination for intersected Cartesian cells. For this purpose, we enhance the k-d tree based intersection determination process to provide essential information of surface mesh for IPT, while concurrently improving the efficiency of the determination process. Our new methods offer automatic generation capabilities for arbitrary complex geometries. Through a series of tests, the new methods illustrate the notable performance improvements with the generation time of less than 4 min for the Cartesian mesh with 108 cells. Overall, our work optimizes Cartesian mesh generation for complex geometries, presenting significant potential for addressing the challenges of moving boundary problems. [ABSTRACT FROM AUTHOR]

A moving model test method based on stagnation pressure measurements is proposed to measure the train aerodynamic drag coefficient. Because the front tip of a high-speed train has a high pressure area and because a stagnation point occurs in the center of this region, the pressure of the stagnation point is equal to the dynamic pressure of the sensor tube based on the obtained train velocity. The first derivation of the train velocity is taken to calculate the acceleration of the train model ejected by the moving model system without additional power. According to Newton’s second law, the aerodynamic drag coefficient can be resolved through many tests at different train speeds selected within a relatively narrow range. Comparisons are conducted with wind tunnel tests and numerical simulations, and good agreement is obtained, with differences of less than 6.1%. Therefore, the moving model test method proposed in this paper is feasible and reliable. [ABSTRACT FROM AUTHOR]

In this work, N-doped graphene and carbon co-modified Li 3 V 2 (PO 4 ) 3 composites (LVP/NGC) are successfully fabricated through a xerogel method for the first time. The obtained architecture combines two types of electronic contact with Li 3 V 2 (PO 4 ) 3 particles: the point-to-face contact of N-doped graphene and the face-to-face contact of N-doped carbon coating layers. Profiting from the favorable complex structure, graphene and carbon coating layers offer an extraordinary network for electron transfer and hence an excellent long-term and high-rate performance. Even tested at the rate of 40 C, the reversible capacity still maintains 86.9 mAh g −1 after 800 cycles without any fading. This work provides a promising route to improve the long-term and high-rate performance of cathodes for LIBs and enlightens us on exploring preferable strategies to develop advanced electrode materials for other energy storage devices. [ABSTRACT FROM AUTHOR]

The article talks about earthquake forecasting, essence of seismic activity, analyzing the anomalies , the energy released by them, analyzing the temporal change for discovering the changes before large earthquakes. It talks about natural orthogonal expansion method, the linear combination with maximum variability, the seismic activity fields describing the activities, information about deep stress state and dielectric property.

Ultra-small Fe 3 O 4 nanocrystals (NCs)/garphene nanosheets (GNSs) composites have been synthesized through a facile gel-like film (GF) assisted method in this work. Fe 3 O 4 NCs with particle size ∼10 nm homogeneously dispersed on 2D GNSs. Profiting from the ultra-small Fe 3 O 4 NCs and GNSs, the composites demonstrate superior long-term and high-rate performance as anode materials for lithium ion batteries. Even at the current density of 5 A g −1 , the reversible capacity still maintains 323.4 mAh g −1 after 700 cycles. This work might enlighten us on exploring preferable strategies to develop advanced metal oxides NCs/GNSs composites anode materials for lithium ion batteries or other energy storage devices. [ABSTRACT FROM AUTHOR]

Li 3 V 2 (PO 4 ) 3 (LVP) nanoparticles were first prepared via a simple sol-gel route, then deposited on graphene oxide nanosheets, and finally a composite of LVP/reduced graphene oxide (LVP/G) was obtained after heat treatment. Scanning electron microscope and transmission electron microscope images demonstrate that LVP nanoparticles are homogenously enwrapped into graphene nanosheets or anchored onto the surface of graphene nanosheets. Compared with pure LVP, LVP/G nanocomposites exhibited better electrochemical performance (118.4 mAhg −1 at 1C, and 112.1 mAhg −1 at 2C after 100 cycles) and higher cycling stability (97% capacity retention after 100 cycles at 1C, and 89.5% after 500 cycles at 20C) as cathode materials for Li ion batteries. The enhanced performance can be attributed to the presence of graphene nanosheets among LVP nanoparticles. Electrochemical impedance spectroscopy indicates that graphene nanosheets significantly improve the electrical conductivity of LVP. The as-prepared LVP/G nanocomposites with superior cycling performance at high-rate have potential applications as cathode materials in Li ion batteries. [ABSTRACT FROM AUTHOR]

Owing to the high energy density, lithium–sulfur batteries (LSBs) have attracted a lot of attention as a representative of new secondary batteries. However, LSBs also face some serious issues in practical applications such as the large volume expansion of S cathode, shuttle effect of lithium polysulfide (LPSs), and dendrite formation of lithium metal anode. In this work, hollow carbon sphere (HCS) was used as a framework, and CoSe2/Se nanorods were uniformly loaded on the HCS surface to form a 3D heterostructured composite (CS/Se/HCS). When used as an active sulfur host, the HCS is conducive to the transport of electrons and Li+; meanwhile, it can suppress the large volume expansion in the electrochemical performance. CoSe2 can effectively adsorb LPSs and accelerate the transformation of LPSs. We also investigated the effect of CoSe2/Se content on the electrochemical performance of the S electrode. Among different CS/Se/HCS samples, the CS/Se/HCS-0.3/S electrode exhibited the best electrochemical performance; at 1C rate, after 500 cycles, it presents a reversible capacity of 511 mA h g−1. This work provided a new idea for the combination of transition metal selenide and carbon materials, which can be used in LSBs and other energy storage devices. [ABSTRACT FROM AUTHOR]

We propose a notion of Frobenius-Perron dimension for certain free \mathbb {Z}-modules of infinite rank and compute it for the \mathbb {Z}-modules of finite dimensional complex representations of unitary groups with nonnegative dominant weights. The definition of Frobenius-Perron dimension that we are introducing naturally generalizes the well-known Frobenius-Perron dimension on the category of finite dimensional complex representations of a finite group. [ABSTRACT FROM AUTHOR]

To address the volume expansion as well as improve the cycling stability and specific capacity of metal selenides, hollow NiCoMnSe (NCMSe) sub-microspheres are synthesised. The as-obtained NCMSe electrodes exhibit superior performance in both LIBs and SIBs and may open up a novel avenue for the rational design of anode materials for both LIBs and SIBs. • A novel trimetallic selenide hollow sphere is prepared for LIB/SIB anodes. • The material exhibits synergistic effect and multielectron redox reactions. • The material shows excellent electrochemical performance. • The ex-situ XRD and XPS provide insight into Li+/Na+ storage mechanism. Highly conductive metal selenides have drawn increasing attention in the field of energy storage. Unfortunately, their application is severely limited by the inferior capacity contribution as well as unsatisfactory cycling stability. Here, we propose a simple and practical way to prepare hollow nickel–cobalt–manganese selenides (NCMSe) submicrospheres. The NCMSe submicrospheres exhibit rich redox reactions during the reaction process into which much more alkali metal ions can be inserted, leading to high reversible capacity and their hollow structure facilitates the contact between the active material and electrolyte to accelerate the redox kinetics. Benefiting from these features, the hollow NCMSe submicrospheres show superior Li–storage capacity (1600 mAh g−1 after 1000 cycles at 2 A g−1) and Na–storage capacity (695 mAh g−1 after 200 cycles at 0.1 A g−1). This work offers a novel insight to the remarkable electrochemical performance anode materials for both lithium and sodium ion batteries. [ABSTRACT FROM AUTHOR]

The aerodynamic forces of the high-speed train pantograph increase sharply with the increase in the operating speed. In this study, we simulated the unsteady aerodynamic performance of a high-speed train with the improved delayed detached eddy simulation (IDDES) method and analyzed the influence of the sinking height of the pantograph platform on the aerodynamic drag and lift coefficients of the high-speed train and pantograph. To verify the simulation model, the numerical results were compared with the wind tunnel test results, showing good agreement. The results indicated that the uncovered cavity formed by the pantograph platform sinking shielded the pantograph base frame to varying degrees, lowered the vorticity around it, but caused disturbances to the flow field near the train surface. The sinking platform of the pantograph effectively reduced the range and amplitude of the positive and negative pressure on the surfaces of pantograph base frame and cavity bottom. In addition, the pantograph drag and lift coefficients decreased with the increase in the sinking height. When the sinking height reached 500 ​mm, the aerodynamic drag and lift coefficients of the pantograph and the entire train decreased by 35.3%, 110.3%, 2.9%, and 21.4%, respectively. • Simulation of the unsteady aerodynamic performance of a high-speed train with IDDES method. • Investigation of effects of platform sinking height on the complex flow field around the pantograph. • Investigation of effects of the platform sinking height on the aerodynamic coefficients of the train and pantograph. [ABSTRACT FROM AUTHOR]

Dendrite formation and water-triggered side reactions on the surface of Zn metal anodes severely restrict the commercial viability of aqueous zinc-ion batteries (AZIBs). In this work, we introduce erythritol (Et) as an electrolyte additive to enhance the reversibility of zinc anodes, given its cost-effectiveness, mature technology, and extensive utilization in various domains such as food, medicine, and other industries. By combining multiscale theoretical simulation and experimental characterization, it was demonstrated that Et molecules can partially replace the coordination H2O molecules to reshape the Zn2+ solvation sheath and destroy the hydrogen bond network of the aqueous electrolyte. More importantly, Et molecules tend to adsorb on the zinc anode surface, simultaneously inhibit water-triggered side reactions by isolating water and promote uniform and dense deposition by accelerating the Zn2+ diffusion and regulating the nucleation size of the Zn grain. Thanks to this synergistic mechanism, the Zn anode can achieve a cycle life of more than 3900 h at 1 mA cm−2 and an average Coulombic efficiency of 99.77%. Coupling with δ-MnO2 cathodes, the full battery delivers a high specific capacity of 228.1 mAh g−1 with a capacity retention of 76% over 1000 cycles at 1 A g−1. [ABSTRACT FROM AUTHOR]

In this study, the sliding grid method is used to simulate a 350 km/h high-speed train passing through a 350 m standard single-line tunnel. The cross-sectional pressure distribution ahead of the train is investigated, the three-dimensional characteristics and propagation mechanism of pressure waves are described based on iso-pressure surfaces, and a newly accurate pressure sensor layout is proposed. The results show that the farther the cross-section is from the train, the smaller the cross-sectional pressure difference is. Influenced by the shape of the train nose and tunnel cross-section, the pressure waves are not simple planar waves, but spherical waves that vary in complexity over the propagation process. As the pressure difference of the 16.6 m cross-section before the train is within 1 Pa, the pressure waves behind this cross-section are defined as planar waves. Besides, the pressure peak-to-peak value difference between the wall and construction clearance reaches 13% at 70–90 m cross-sections, so the pressure sensors should be placed on the surface of the appurtenances rather than on the tunnel wall. In summary, this study is significant for understanding the formation and transmission mechanisms of pressure waves and guiding the scientific layout of pressure sensors in tunnels. [ABSTRACT FROM AUTHOR]

Regulating the molybdenum disulfide (MoS 2) anodes with controllable phase and structure shows promising application for advanced lithium-ion storage performance. Herein, phase- and structure-regulated 1T@2H MoS 2 nanosheet @TiO 2 –B nanobelts are synthesized via a facile hydrothermal and ammoniation strategy. The stable 1T@2H MoS 2 is revealed by the formation of N–Mo covalent bonds via subtle structural analysis, including XPS, Raman and TEM analysis. TiO 2 nanobelts serve as the backbone for MoS 2 nanosheets to form highly active edged nanostructure. As a proof-of-concept study, this well-devised 1T@2H MoS 2 @TiO 2 –B electrode delivers much higher capacities of 830 mA h g−1 at 100 mA g−1 after 200 cycles. Even at a large rate of 2000 mA g−1, the reversible capacity was still maintained at 530 mA h g−1 after 1000 cycles. In addition, the EIS, GITT and pseudocapacitance analyses further demonstrate the introduced 1T MoS 2 not only boost the lithium-ion diffusion coefficient, but also modify the electrochemical kinetics of the composite anodes. This concept of phase engineering strategy will open opportunities for advanced energy storage applications and beyond. [Display omitted] [ABSTRACT FROM AUTHOR]

Combining 2D MoS2 with other transition metal sulfide is a promising strategy to elevate its electrochemical performances. Herein, heterostructures constructed using MnS nanoparticles embedded in MoS2 nanosheets (denoted as MnS‐MoS2) are designed and synthesized as anode materials for lithium/sodium‐ion batteries via a facile one‐step hydrothermal method. Phase transition and built‐in electric field brought by the heterostructure enhance the Li/Na ion intercalation kinetics, elevate the charge transport, and accommodate the volume expansion. The sequential phase transitions from 2H to 3R of MoS2 and α to γ of MnS are revealed for the first time. As a result, the MnS‐MoS2 electrode delivers outstanding specific capacity (1246.2 mAh g−1 at 1 A g−1), excellent rate, and stable long‐term cycling stability (397.2 mAh g−1 maintained after 3000 cycles at 20 A g−1) in Li‐ion half‐cells. Superior cycling and rate performance are also presented in sodium half‐cells and Li/Na full cells, demonstrating a promising practical application of the MnS‐MoS2 electrode. This work is anticipated to afford an in‐depth comprehension of the heterostructure contribution in energy storage and illuminate a new perspective to construct binary transition metal sulfide anodes. [ABSTRACT FROM AUTHOR]

With increasing train speed, aerodynamic effects pose a safety risk for train operations, especially for trains passing each other, the strong transient aerodynamic loads could result in window breakage, sideward shaking, trackside worker injuries, and facility fatigue damage. Unsteady compressible numerical simulation is carried out in this paper to investigate the transient flow field induced by two maglev trains passing each other at a speed of 430 km/h in open air. Good agreement is obtained between the numerical method and full-scale experiment results, with differences smaller than 6%. The transient pressure change on train surfaces and the slipstream distributions on trackside are analysed. It was noted that the peak values of pressure coefficient for two trains passing each other are approximately twice as larger as that of a single train passing because of the blocking effect and interference by the motion of the other train in the opposite direction. The maximum slipstream velocity occurs at a height of 1.4 m from the top of rail (TOR) at the meeting position, and the relationship between the slipstream velocity and the distance from the centre of rail (COR) is obtained, based on which, the safe distance is calculated. [ABSTRACT FROM AUTHOR]

Abstract This study investigates the alleviation effect of partially enlarged cross-section on tunnel aerodynamics. By comparing the numerical results to moving model tests data, the SST k-ω turbulence model and hybrid grid are used for the numerical simulations of high-speed train passing through tunnel. The reduction effects of three parameters for the enlarged section are analyzed, i.e., length, cross-sectional area, and slope. Systematic numerical simulations show that the terminal location of the enlarged section should be close to the location of the initial compression wave amplitude along tunnel length direction. The reduction rates of the pressure transient amplitude and the average pressure variation follow a second order polynomial equation with the increase of the enlarged section area, and increase with the increase of enlarged section slope. Positive enlarged section slope is applied for reducing pressure transients in the tunnel. Furthermore, an engineering application equation is proposed, with which the reduction rates of enlarged sections on the pressure transient amplitude and the average pressure variation can be estimated effectively. The equation generalized in this study could well guide the tunnel design process. Highlights • The SST k-ω turbulence model with hybrid grid achieved best accuracy in simulation. • The optimum length of the enlarged section is obtained. • The relationship of pressure transients and cross-sectional area is derived. • An engineering equation regarding pressure transient reduction is proposed. [ABSTRACT FROM AUTHOR]

Lead (Pb) exposure and high-fat diet (HFD) trigger neurotoxicity, which may involve neuroinflammation. However, the mechanism by which combined Pb and HFD exposure induces nucleotide oligomerization domain-like receptor family pyrin domain 3 (NLRP3) inflammasome activation has not been fully elucidated. The Sprague-Dawley (SD) rat model of exposure to Pb and HFD was established to reveal the influence of co-exposure on cognition and identify signaling clues that mediate neuroinflammation and synaptic dysregulation. PC12 cells was treated with Pb and PA in vitro. Silent information regulator 1 (SIRT1) agonist (SRT 1720) was employed as intervention agent. Our results showed that Pb and HFD exposure induced cognitive impairment and lead to neurological damage in rats. Meanwhile, Pb and HFD could stimulate the NLRP3 inflammasome assembly and activate caspase 1, releasing proinflammatory cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18), further promoting neuronal cell activation and amplifying neuroinflammatory responses. Additionally, our findings suggest that SIRT1 plays a role in Pb and HFD induced neuroinflammation. However, the use of SRT 1720 agonists showed some potential in alleviating these impairments. Pb exposure and HFD intake could induce neuronal damage through activation of the NLRP3 inflammasome pathway and synaptic dysregulation, while the NLRP3 inflammasome pathway may be rescued via activating SIRT1. [Display omitted] • Pb exposure combined with HFD exacerbated synaptic dysfunction in rats. • Combined exposure to Pb and HFD triggered extensive NLRP3 inflammasome activation. • Pb exposure combined with HFD decreased the expression of SIRT1 in rats. • SRT 1720 suppressed the activation of NLRP3 induced by Pb and PA in PC12 cells. [ABSTRACT FROM AUTHOR]

Recent years, as a competitive anode material for lithium ion batteries (LIBs), tungsten disulfide (WS 2 ) has attracted significant attention for its high theoretical capacity, abundant resources and low cost, but how to improve the cycle stability and reversible capacity is still an important research subject. In this work, stable metallic WS 2 anchored on carbon fiber cloth was fabricated as flexible anode for LIBs. The transversal displacement of S atoms in WS 2 was induced by incorporation of N atoms, and the stability of metallic phase WS 2 was ensured by the formation of N-W covalent bonds. The results of electrochemical measurement and dynamics analysis demonstrate that the incorporation of metallic phase could not only reduce the initial discharge capacity loss, but also improve the reversible capacity than traditional semi-conducting phase WS 2 . [ABSTRACT FROM AUTHOR]

Nanostructured MoS 2 is emerging as a prospective material for lithium ion batteries. However, undesirable lattice stress results in inhomogeneous phase change and slow kinetics, which leads to rapid decay of cyclic stability. Initial phase conversion before the electrochemical intercalation can alleviate this problem. Herein, MoS 2 nanosheets with partial 2H→1T phase transition under incorporative nitrogen atoms were synthesized controllably on the carbon cloth (CC). The hierarchical self-supporting three-dimensional (3D) 1T@2H MoS 2 @CC was confirmed and such a freestanding flexible electrode exhibited a significant improvement in the electrochemical characteristics. A strong correlation between such phase transition properties and electrochemical characteristics is established. This work provides an intriguing and effective approach on phase engineering of transition metal dichalcogenides (TMDs) for enhanced electrochemical energy storage. [ABSTRACT FROM AUTHOR]

The "shuttle effect", tardy reaction kinetics and volume change of sulfur cathode limit the wide application of Li-S batteries (LSBs). In this work, a composite of flower-like CoOOH decorating hierarchical porous carbon (CoOOH-HPC) was successfully synthesized and utilized as a sulfur host for LSBs. SEM and TEM images exhibited that the flower-like CoOOH formed by nanosheets was uniformly dispersed on the hierarchical porous carbon which was constructed by carbon spheres and nanotubes. Nitrogen adsorption/desorption isotherm and pore size distribution revealed that the ultrahigh specific surface area and suitable uniform mesopores of the CoOOH-HPC. Benefitting from the perfect combination of CoOOH and HPC, the CoOOH-HPC/S electrode delivered satisfactory electrochemical performance. It remained a discharge capacity of 550.9 mA h g−1 after 270 cycles at 0.5 C, with a low capacity decay rate of 0.017 % per cycle and a stable coulombic efficiency (over 96 %). Besides, the CoOOH-HPC/S electrode with a high sulfur loading of 2.8 mg cm−2 can demonstrate a discharge capacity of 357.91 mA h g−1 after 500 cycles, with the capacity decay rate of 0.08 % per cycle. This work provided a new method for preparing a variety of metal-based compound decorative hierarchical porous carbon composites, which can be used in LSBs and other energy storage and conversion devices. [Display omitted] • A composite sulphur host of CoOOH decorating hierarchical porous carbon (CoOOH-HPC) was synthesized. • The CoOOH-HPC exhibits ultrahigh specific surface area and suitable pore volume. • The perfect structure facilitates wetting of electrolyte and diffusion of electron/Li+ in solid phase • The CoOOH can adsorb the lithium polysulfide through chemical adsorption and accelerate the conversion of the lithium polysulfide to Li 2 S [ABSTRACT FROM AUTHOR]

• Study the mitigation effect of pressure fluctuations caused by train intersection in a tunnel with the enlarged end. • Consider the effects of the total length of tunnels and unit number of trains on the optimal length of the enlarged section. • Analyse the mitigation principle of the pressure fluctuations impacted upon trains. • Obtain an optimal length coefficient to attain the maximum mitigation of the pressure fluctuations. Intense pressure fluctuations generated by the intersection of high-speed trains (HSTs) in a tunnel are unfavourable for the comfort of passengers and the safety of HSTs and tunnel facilities. This study numerically investigated the mitigation principle of the pressure fluctuation impacted upon HSTs using the enlarged tunnel end with taking into account the total tunnel length and the unit number of HSTs. Moving model tests were also performed to validate the numerical method based on the unsteady RANS equations and RNG k - ε turbulence model. The numerical results show that the enlarged end of a tunnel can manifestly alleviate the negative pressure induced by the train intersection and the length ratio of the optimal length of the enlarged section to the total length is in the range of 0.26–0.28. The optimal length of the enlarged section can be implemented by synchronising the contact of the derived waves with the train intersection. Moreover, the increase in the marshalling number of HST augments the mitigation effect of the enlarged section. This study gives insight into the mitigation of the pressure fluctuation in tunnels and can provide valuable data and a theoretical basis for the tunnel design when considering the aerodynamic effect of HST intersection. [ABSTRACT FROM AUTHOR]

The analysis of drought propagation has garnered mounting attention in the changing global environment. The current studies tend to focus on the propagation characteristics from meteorological to hydrological drought in rivers. Lakes, despite being a key component of watershed ecosystems, have received little attention to their response to meteorological and hydrological droughts. To this end, here, we investigated the characteristics of propagation from meteorological to hydrological drought for a lake in a changing environment. To determine the drought propagation time from meteorological to hydrological drought, we analyzed correlations between the standardized precipitation index (SPI), standardized runoff index (SRI), and standardized water level index (SWI). Lake Baiyangdian in China served as the case study. The results showed that meteorological droughts occur at high frequency but are short in duration, indicating that not every meteorological drought will necessarily lead to a hydrological drought. By contrast, lake hydrological droughts have low frequency and long duration and feature more severe consequences. Comparing drought characteristics before and after a changing environment, we found a reduced frequency of the SPI, SRI, and SWI, yet their duration was prolonged. For the SWI especially, these results were even more pronounced, which suggests the changing environment enabled further intensification of the lake hydrological drought. In addition, more time was needed for a meteorological drought to transition into a lake hydrological drought after a changing environment. [ABSTRACT FROM AUTHOR]

• Obtained the influence of the length of the heating zone on the peak value of the initial compression wave. • Obtained the influence of the length of the heating zone on the peak value of the initial expansion wave. • Study the effect of different heating zone lengths on the peak value of the train's initial compression wave. • The result of the initial temperature field of the tunnel is obtained. • Study the dynamic change process of temperature during train operation. In this paper, through experimental and numerical simulation methods, the influence of the tunnel heating zone length on the pressure wave peak and temperature field changes is investigated in tunnels with different heating zone lengths. The accuracy of the applied simulation algorithm is verified against experimental data from moving model tests. Via numerical simulations, the changes in the pressure wave peak value and temperature field are explored with five heating zone lengths. For the compression wave, this research revealed that when L H (length of the heating zone) < L T (length of the train) and that with an increase in L H , the peak value of the initial compression wave notably decreases. When L H > L T , the compression wave peak value remains basically stable. In regard to the expansion wave at tunnel measurement points, for L (from tunnel entrance) ⩽ 110 m, the initial expansion wave peak exhibits small fluctuations. At L > 110 m, with an increase in the heating zone length, the peak value of the expansion wave peak gradually decreases. In addition, the dynamic temperature field changes. The obtained research results provide a new idea to reduce the peak pressure value in a tunnel. In addition, this study provides a method for pressure wave mitigation during tunnel design and guidance for passenger comfort improvement in future city railway tunnels. [ABSTRACT FROM AUTHOR]

[Display omitted] • Plum blossom-like CoSe 2 /N-doped carbon nanotubes S host was synthesized. • DFT calculation confirms the catalytic performance of CoSe 2 for Li 2 S x conversion. • The plum blossom-like structure is beneficial to the diffusion of electron/Li+. • DFT calculation confirms the chemical adsorption of CoSe 2 to Li 2 S x. • The CoSe 2 /hNCTs/S cathode delivers satisfactory lithium storage performance. Lithium-sulfur batteries (LSBs) have attracted wide attention as one of the most potential secondary batteries in the next generation. However, the low sulfur utilization, serious "shuttle effect", and large volume expansion of the sulfur cathode restrict the performance of LSBs. Here, CoSe 2 decorated hollow N-doped carbon nanotubes (CoSe 2 /hNCTs) were synthesized firstly, and then the CoSe 2 /hNCTs were used as a sulfur host to prepare a multifunctional CoSe 2 /hNCTs/S cathode. DFT calculations confirm that the CoSe 2 not only efficiently adsorbs lithium polysulfides (LiPSs), but also exhibits good catalytic performance for the conversion of LiPSs. SEM and TEM images indicate that the CoSe 2 uniformly disperses on the surface of the polypyrrole nanotube-derived hNCTs, like plum blossoms. The hNCTs with a morphology of plum blossom branches provide a high conductive network and prohibit large volume expansion during the electrochemical process. And the plum petal-like CoSe 2 on the hNCTs surface acts as a catalyst and an efficient polysulfides trap. The CoSe 2 /hNCTs/S cathode delivers a satisfactory lithium storage performance, which presents reversible capacities of 1156 and 640 mA h g−1 at 0.5 and 5C, respectively. Simultaneously, the cathode demonstrates excellent cycle stability with a slow capacity decay rate of 0.069% per cycle in 1000 cycles at 1C rate. This work provides a new idea for constructing composites of transition metal selenides and carbon materials, promoting the practical applications of LSBs. [ABSTRACT FROM AUTHOR]

With the increase in the speed of metro trains, the aerodynamic effects caused by the train passing through the tunnel, especially the pressure change, will be significantly enhanced. This pressure will have a significant effect on the auxiliary facilities in the tunnel and the passengers in the carriage. Based on the sliding grid technique, Fluent software was used to simulate the aerodynamic performance of six trains passing through different shield transfer structures, and the influences of the shield cross-section area, length, and form on train aerodynamic performance were studied. The results show that when the cross-sectional area of the shield transfer structure increases from 42 m2 to 62 m2, the positive pressure peak P max on the train surface increases significantly, and the peak-to-peak value and positive pressure gradient peak in the large-section tunnel are increased by 20.50 % and 106.83 %, respectively; when the length of the shield transfer structure is increased from 80 m to 120 m, the positive pressure peak and pressure gradient peak in the large-section tunnel are increased by 22.53 % and 21.70 %, respectively; for constant cross-sectional area and ellipsoidal structural forms, the slanting structural form has a smaller train surface pressure amplitude as well as a smaller peak pressure and peak pressure gradient in a large-section tunnel. These findings will contribute to the design of shield transfer structure in subway and tunnel systems. [ABSTRACT FROM AUTHOR]

Vacuum Tube Transportation (VTT) system utilizes the low-pressure environment to achieve aerodynamic drag reduction and reduce the energy consumption of high-speed trains. Within this system, even for trains operating at subsonic speed, the flow acceleration around the streamlined train may leads to local supersonic flow. The appearance of the supersonic flow will dramatically alter the flow field structure and aerodynamic load of the high-speed train. Therefore, this study investigates two types of representative flow fields under different blockage ratio through the improved delayed detached eddy simulation (IDDES) method. The initialization, propagation, reflection and intersection process of shock waves in transonic case are captured and analyzed. It is shown that, the boundary layer thickness and width of vortex group in wake has experienced a slight increase with the increase of vacuum level. Compared with the subsonic case, the occurrence of choked flow and shock wave in transonic flow field lead to a decrease of wake region's vortex group width. As a result, the total drag coefficient of the train is increased by approximately one order of magnitude, and the dominant St number of tail car's drag coefficient has shifted from 0.16 to 0.11. [ABSTRACT FROM AUTHOR]

As a nitride semiconductor with a wide bandgap, AlN is a promising material because of its broad applications in electronics and opto-electronics. In this study, a primary AlN seed was prepared with 6H–SiC as the foreign substrate by using the physical vapor transport (PVT) method. Results from X-ray diffraction, Raman spectroscopy and electron backscatter diffraction show that the growth pattern of AlN on 6H–SiC is [0001]AlN‖[0001]6H–SiC and [101¯0]AlN‖[101¯0]6H–SiC. Based on this finding, a particle model of AlN growth on the 6H–SiC substrate is drawn, and the bonding mode during the growth process is analysed. The internal stress of this growth mode is evaluated by the texture component and Raman spectra. An almost uniform colour of the texture component confirms the consistency of the structure. The Raman spectra and theoretical mode of the AlN seed show that the stress remains at a very low level after the growth thickness exceeds a certain value, and then decreases as the AlN layer becomes thicker. This in-depth study will enhance understanding of the growth mode and stress distribution of AlN grown on 6H–SiC substrate. [ABSTRACT FROM AUTHOR]

Metformin is commonly used, but approximately 20% of patients experience gastrointestinal intolerance, leading to medication discontinuation for unclear reasons and a lack of effective management strategies. In this study, the 18 fecal and blood samples were analyzed using 16S rRNA and mRNA transcriptome, respectively. These samples included 3 fecal and 4 blood from metformin-tolerant T2D patients before and after metformin treatment (T and Ta), 3 fecal and 5 blood from metformin-intolerant T2D patients before and after treatment (TS and TSa), and 6 fecal samples from healthy controls. The results showed that certain anti-inflammatory gut bacteria and gene, such as Barnesiella (p = 0.046), Parabacteroides goldsteinii (p = 0.016), and the gene JUND (p = 0.0002), exhibited higher levels in metformin-intolerant patients, and which decreased after metformin treatment (p < 0.05). This potentially invalidates patients' anti-inflammatory effect and intestinal mucus barrier protection, which may lead to alterations in intestinal permeability, decreased gut barrier function, and gastrointestinal symptoms, including diarrhea, bloating, and nausea. After metformin treatment, primary bile acids (PBAs) production species: Weissella confusa , Weissella paramesenteroides , Lactobacillus brevis , and Lactobacillus plantarum increased (p < 0.05). The species converting PBAs to secondary bile acids (SBAs): Parabacteroides distasonis decreased (p < 0.05). This might result in accumulation of PBAs, which also may lead to anti-inflammatory gene JUND and SQSTM1 downregulated. In conclusion, this study suggests that metformin intolerance may be attributed to a decrease in anti-inflammatory-related flora and genes, and also alterations in PBAs accumulation-related flora. These findings open up possibilities for future research targeting gut flora and host genes to prevent metformin intolerance. • Metformin intolerance mechanism in Chinese individuals may unique. • Intolerant subjects show a decline in anti-inflammatory gut bacteria and genes. • Gut flora changes in intolerant subjects may cause an excess of primary bile acids. • Inflammation and primary bile acids-related flora and genes may impact intolerance. [ABSTRACT FROM AUTHOR]

A moving model (1/20 scale) was used to study the effect of high temperature at the entrance of a tunnel on the aerodynamic performance of a high-speed train passing through it. The air in the tunnel was heated using highly-precise, self-controlling, ultra-thin, silicone rubber heating devices that were firmly attached to the inner surface of the tunnel (covering the first 2 ​m of the tunnel from the entrance). When the specified temperature was reached, tests were performed using a model train moving at different speeds. The experimental results were used to compare and analyze the pressure fluctuations and propagation of pressure waves under normal and localized high-temperature conditions. The results show that the peak-to-peak value of the transient pressure on the tunnel surface decreases by 5–7% in the presence of a normal ambient and high temperature tunnel mode. In addition, the corresponding difference on the surface of the head of the train is 3–4%. Hoping this experimental study will encourage theoreticians to investigate the mechanism responsible for the generation of transient pressures in localized high temperature railway tunnels. The results can provide guidance and support for researchers seeking to improve passenger safety and comfort in high temperature railways. • Study the influence of the local high temperature difference by a moving model test. • Obtain the aerodynamic performance of trains passing through the tunnel under heat. • Compare the pressure curve difference between normal temperature and heating. • Analyze the difference of the pressure change and pressure propagation characteristic. • Study the pressure peak-to-peak difference under normal and heating. [ABSTRACT FROM AUTHOR]

Alleviation of the pressure transients caused by high-speed trains intersecting in a tunnel with partially reduced cross-section is investigated by numerical simulation. The RNG k - ε turbulence model and hybrid grid are adopted for the numerical simulation, which is validated by the moving model test. Two factors, the length of reduced section (L) and the train marshalling number, are considered to analyse the alleviation effect. The results show that, for reduction of the pressure transients induced by the intersection of three-car marshalling trains, the location of the change in cross-section is supposed to be near the location of the maximum value of the initial expansion wave (L → 240 ​m). In addition, for four-car marshalling trains intersecting in a tunnel of L ​= ​240 ​m, the excavation volume of the tunnel (tunnel volume) decreases by 14.4%, and the average pressure amplitude on the train surface decreases by 7.9%. Especially the pressure amplitude at the measurement point in the streamlined area of the tail car decreased by 28.6%. The reduced section tunnel has a good effect on decreasing the pressure transients around train body and the tunnel excavation volume (construction cost), which helps the tunnel design process. • The influence of the reduced section on the pressure transients in high-speed train tunnels are analysed. • For high-speed trains intersecting in the tunnel, the optimal location of the change in cross-section are obtained. • The excavation volume of the tunnel and the average train surface pressure amplitude decreases by 14.4% and 7.9%. [ABSTRACT FROM AUTHOR]

Background: LncRNA-ZNF281 suppresses glioma, whereas its role in hepatocellular carcinoma (HCC) is unclear. This study aimed to investigate the interaction between ZNF281 and miR-539 in HCC. Materials and Methods: This study included 66 HCC patients (40 men and 26 women; 36-68 years, 53.1 ± 6.2 years) who were selected from the 133 HCC cases admitted to The First Affiliated Hospital of Fujian Medical University from February 2011 to June 2014. Levels of ZNF281 and miR-539 expression in two types of tissues (HCC and nontumor) were measured by performing quantitative polymerase chain reaction (qPCR). Dual-luciferase assay was performed to analyze the interactions between miR-539 and ZNF281 in both SNU-475 and PLHC-1 cells. The effects of ZNF281 and miR-539 overexpression on the invasion and migration of HCC cells were analyzed by performing transwell assays. Results: The authors showed that ZNF281 was upregulated and miR-539 was downregulated in HCC tissues and were negatively correlated. High levels of ZNF281 and low levels of miR-539 predicted the poor survival of HCC patients. Overexpression analysis showed that ZNF281 and miR-539 overexpression led to the downregulation of each other. Transwell assays showed that ZNF281 overexpression led to enhanced and miR-539 overexpression led to suppressed HCC cell invasion and migration. In addition, miR-539 overexpression attenuated the effects of ZNF281 overexpression. Conclusions: Therefore, ZNF281 may interact with miR-539 to promote HCC cell invasion and migration. [ABSTRACT FROM AUTHOR]

We use geometry to give a short proof of an equivariant Pieri rule in the classical flag manifold. This rule is due to Robinson, who gave an algebraic proof. [ABSTRACT FROM AUTHOR]

Abstract The air-conditioning units (ACUs) on high-speed trains are responsible for cooling the passenger compartment. Insufficient condensing air flux through the ACU may lead to a suboptimal cooling and causes dangerous levels of overheating or even a shutdown of the ACU itself. In this paper, the air flow through ACU at different speeds of a high-speed train is investigated numerically. A significant drop of the condensing air flux during the train operation at higher speed is observed. This phenomenon is related to the interaction of the air flow through the ACU and the boundary layer on the roof of the train. Simulations show that the motion of the train creates a region of negative pressure above the ACU inlets and a region of positive pressure above the outlets. Thus, a particular structural optimization of the air outlets aimed at reducing the pressure buildup is proposed. The proposed numerical method can be used serve to investigate and to optimize the performance the ACUs on high-speed trains under different structural modifications. [ABSTRACT FROM AUTHOR]

In this study, boron carbon nitride (BCN) nanosheets were used as a substrate coating material to grow gallium nitride (GaN) crystals by hydride vapor phase epitaxy. By adjusting the solution viscosity, BCN nanosheets were uniformly coated on a MOCVD-GaN/Al2O3 substrate with spin-coating technology. Experiments with different conditions and the growth results showed that the BCN solution with a concentration of 0.0025 mg mL−1 and a viscosity of 14.30 mPa s was optimal for GaN growth. The quality of GaN crystals grown with BCN coating was significantly improved. The full width at half maximum (FWHM) values of the (002) and (102) planes were 192 and 213 arcsec, respectively, and the inside of the crystal was nearly unstressed. Compared with untreated or unevenly coated substrates, uniformly distributed BCN nanosheets effectively prevented the extension of threading dislocations, as well as promoted the lateral epitaxial growth of crystals and formation of small pores at the interface, which helped in relieving the stress inside the crystals and realizing the self-separating properties of GaN crystals. A GaN nucleation mechanism on the BCN nanosheets was discussed. EBSD and TEM results indicated that the crystal disorientation was reduced by using the BCN nanosheet-coated substrate. In general, the BCN nanosheets presented a broad application prospect in crystal growth. [ABSTRACT FROM AUTHOR]

Abstract This study presents a model-based approach for assessing the impact of climate change on hydropower potential in the Nanliujiang River Basin of China. The variable infiltration capacity (VIC) hydrological model was proved to be able to do a good runoff simulation after 1000 times of calibration and validation, while it has greater uncertainty in the simulation of high flow and low flow. Coupling the VIC model with five climate models, the spatial and temporal distributions of water resources in the future are analyzed, and the uncertainty analysis shows that the multi-model ensemble results can more reliably reflect future climate change. Then, the hydropower potential of the whole river basin in the future is analyzed in order to allow for a more realistic picture of future hydropower planning. The results of this study indicate that, different degrees of future alterations in river discharge and the spatial and temporal distributions of water resources have to be expected, leading to an increase of 7.7%–15.6% in hydropower potentials under the scenario of RCP2.6, RCP4.5 and RCP8.5. Highlights • A VIC model coupled with five climate models is built in the Nanliujiang River basin. • The spatial and temporal distributions of water resources in the future are analyzed. • The uncertainty of hydrological model and climate change prediction results are analyzed. • The hydropower potential of the whole river basin in the future is calculated. [ABSTRACT FROM AUTHOR]

Abstract In this study, the delayed detached eddy simulation approach based on the shear-stress transport κ-ω turbulent model was performed to simulate the unsteady aerodynamic performance of the pantograph of a high-speed train using yaw angles of 0°, 10°, 20°, and 30° with crosswind to determine how the yaw angle influenced the numerical simulation results. For validation, the simulation results were compared with wind tunnel test results, demonstrating good agreement. Additionally, the aerodynamic forces and instantaneous and time-averaged flow fields around the pantograph were analyzed. With increasing yaw angle, the flow field asymmetry and vortex intensity near the pantograph increased, the wake flow became more turbulent, and the unsteady aerodynamic characteristics became more obvious. Thus, the yaw angle affected the velocity field distribution near the pantograph considerably, especially in the wake flow area. The aerodynamic forces on the pantograph were also computed, and their time histories were used to reveal the characteristic frequencies of the flow motion around the pantograph. The time-averaged aerodynamic coefficients and their fluctuations increased with increasing yaw angle. In addition, the power spectral densities of the aerodynamic coefficients exhibited obvious peaks, while the aerodynamic coefficient frequency band was wider with crosswind than without crosswind. Highlights • The unsteady aerodynamic performance of the pantograph of a high-speed train was investigated with various yaw angles. • The aerodynamic forces and instantaneous and time-averaged flow fields were analyzed. • With increasing yaw angle, the flow field asymmetry and vortex intensity increased. • The yaw angle significantly affected the velocity field distribution near the pantograph. • The time-averaged aerodynamic coefficients and their fluctuations increased with increasing yaw angle. [ABSTRACT FROM AUTHOR]

The soil moisture dynamics of the root zone and its hydrological interactions with the vadose zone below in deep groundwater table condition has not been thoroughly elucidated to date, thereby hampering our adaption of irrigation in farmlands with a deep groundwater table. In this study, vadose zone modelling detailing the soil moisture dynamics of the root zone in farmland with a deep groundwater table in the North China Plain, was presented to investigate the regular pattern of the soil hydrological processes during crops growing periods and to examine its implications for adjustment of irrigation applications of wheat and maize. Deep percolation reached over 30% of the total water input while root zone hardly obtain any moisture supplement from the vadose zone below, during the crops growing period, from April to September in 2012 and 2013, both being typical wet years. Corresponding to the seasonal distribution of precipitation, the soil evaporation and deep percolation were concentrated in the growing period of maize, rather than in the growing period of wheat. Additionally, soil water storage in the root zone before irrigation applications in the growing periods of wheat can be 100–120 mm less than it in growing periods of maize. On the basis of these soil hydrology characteristics in the root zone, the current irrigation scheduling for wheat could be adjusted to be more adequate but less frequent, while intensity and frequency of irrigation applications for maize should both be decreased to reduce deep percolation and soil evaporation. An example simulation in the crop growing period of 2012, showed that deep percolation and soil evaporation can be decreased by 36% and 18% respectively, with little impacts on crops transpiration, under the adjusted irrigation practice. This research suggests the direction and potential of adjustment of irrigation scheduling in farmlands with a deep groundwater table from the perspective of soil hydrological processes. [ABSTRACT FROM AUTHOR]

As one of appealing storage patterns of solar energy, the efficient photocatalytic hydrogen evolution from water splitting has great potentiality in sustainable development for renewable energy, but it still suffers the low conversion level due to sluggish spatial behavior of photocarriers. Herein, on the basis of phase engineering theory, a novel conceptual design of energy band-gradient distribution is presented to consolidate the spatial transportation continuity of photocarriers, which is realized in the phase junction of CdS for the first time. Further being integrated with black phosphorus (BP) nanodots, the utilization of incident photons is extended to cover broad solar light-responsive window, and the p-n junctions with powerful internal electric fields resemble many accelerators distributed on the energy band-gradient pathway, thus furnishing sufficient internal dynamical transfer force for separation and migration of photocarriers with prolonged lifetime. The peculiar compound photocatalyst exhibits an excellent hydrogen evolution activity of 163.65 μmol·h−1·g−1 and 5.72 mmol·h−1·g−1, as well as high apparent quantum yields (0.73 % and 25.7 % at 420 nm) under different conditions (with or without sacrificial agents). This study proposes a new exploitation strategy for the manipulation of energy band-gradient configuration in designing superior photocatalytic systems with available solar conversion efficiency. [Display omitted] • A novel energy band-gradient distribution is realized in the phase junction of CdS. • P-n junctions are established in BP/CdS system by introducing BP nanodots. • The transfer continuity of photocarriers is enhanced by the internal electric fields. • Excellent water reduction ability is reflected on this photocatalytic system. [ABSTRACT FROM AUTHOR]