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Vapor shearing is a common issue encountered in the operations of falling film heat exchangers. The vapor stream effect depends on its orientation. This study investigates liquid film hydrodynamics and heat transfer performance under the influence of vapor streams from different orientations. The results indicate that both orientation and velocity of vapor determine the encountering time and position of the films on the tube's two sides. The liquid film thickness uniformity and the liquid column deflection vary significantly depending on the orientation and velocity of the vapor. Zones of accelerated liquid film, climbing liquid film, liquid stagnation, and transition of liquid film flow pattern are observed. The gradient of film thickness along the tube axis and the deflection in time-averaged peripheral film thickness increase as the vapor orientation varies from 0° to 90° and subsequently decrease as the vapor orientation varies from 90° to 180°. Vapor streams have more pronounced effects on time-averaged peripheral film thickness in regions close to the liquid inlet and outlet. Vapor streams result in changes in peripheral heat transfer coefficients toward the downstream side depending on the orientation and velocity of the vapor. The impact of vapor streams on the overall heat transfer coefficient does not directly correlate with the velocity of the vapor when maintaining the same orientation. [ABSTRACT FROM AUTHOR]

Using DMDODGA as the carrier, the transportation and separation behavior of Eu(III) and La(III) were studied using a plate-type supported liquid membrane. La(III) and Eu(III) reach their maximum transport rates at feed phase nitric acid concentrations of 2 and 4 mol/L, which are 72.41 (± 2.12)% and 77.80 (± 2.45)%; Increasing the concentration of NO3− in feed phase will promote the transport of both ions. The change of HNO3 concentration in feed phase had major effect on the separation of Eu(III)/La(III), and the co-transport of Eu(III)/La(III) was observed when the concentration of NO3− was 3 mol/L. [ABSTRACT FROM AUTHOR]

Inconel 718 offers high oxidation resistance, mechanical strength, and heat resistance, which enables turbofan engines to maintain excellent performance in an operating environment of 1000 °C. However, these properties make Inconel 718 difficult to machine with conventional machining techniques. Water-jet guided laser (WJGL) is a composite processing technology that combines water cooling and laser ablation technology, which is advantageous and promising for processing Inconel 718. While, the water layer on the substrate surface in processing limits WJGL's ability to ablate the metal, which leads to burrs formed when manufacturing groove structures. Therefore, a new method for manufacturing groove structure on Inconel 718 by annular gas-assisted water-jet guided laser (AGAWJGL) is proposed in this paper. In this study, the burr is reduced, and the material removal efficiency is improved by removing the water layer from the substrate surface with a gas-assisted. Then, groove processing experiments are performed on Inconel 718 metal plates with a thickness of 1 mm. The experimental results show that the average size of burrs reduces by 36%, and the depth of grooves increases by 13%. These provide the theoretical foundation for the WJGL machining of Inconel 718. [ABSTRACT FROM AUTHOR]

Two-phase flow patterns are critical in falling film heat devices. Hydrodynamic characteristics of turbulent falling films across a horizontal triangular tube bundle were studied under a range of film Reynolds numbers and contact angles. A flow pattern map based on the k-means clustering approach was proposed after the intercolumn two-phase flow patterns were grouped. The results demonstrated that that the intercolumn liquid-vapor flow patterns in a horizontal tube bundle could be effectively and reasonably grouped using the k-means clustering approach according to the results of the void fraction and interface area. There are four intercolumn liquid-vapor flow patterns that were identified: bubbles flow, annular-slug-column flow, half-annular flow, and multi-bridges flow. The annular-slug-column flow pattern and the multi-bridges flow pattern are next to one another in the flow pattern map and are capable of transitioning one into the other. It is only through the two transitional flow patterns that the half-annular-column flow pattern and bubbles flow pattern can turn to one another. In the bubbles' flow pattern and half-annular-column flow pattern, respectively, the highest and least averaged heat transfer coefficients are attained. Simply raising the film Reynolds number or lowering the contact angle will not produce the best heat transfer results. [ABSTRACT FROM AUTHOR]

Imbalanced classification is widely referred in many real-world applications and has been extensively studied. Most existing algorithms consider alleviating the imbalance by sampling or guiding ensemble learners with punishments. The combination of ensemble learning and sampling strategy at class level has achieved great progress. Actually, specific hard examples have little benefit for model learning and even degrade the performance. From the view of identifying classification difficulty of samples, one important motivation is to design algorithms to finely equip different samples with progressive learning. Unfortunately, how to perfectly configure the sampling and learning strategies under ensemble principles at the sample level remains a research gap. In this paper, we propose a new view from the sample level rather than class level in existing studies. We design an ensemble approach in pipe with sample-level gradient resampling, that is, balanced cascade with filters (BCWF). Before that, as a preliminary exploration, we first design a hard examples mining algorithm to explore the gradient distribution of classification difficulty of samples and identify the hard examples. Specifically, BCWF uses an under-sampling strategy and a boosting manner to train T predictive classifiers and reidentify hard examples. In BCWF, moreover, we design two types of filters: the first is assembled with a hard filter (BCWF_h), whereas the second is assembled with a soft filter (BCWF_s). In each round of boosting, BCWF_h strictly removes a gradient/set of the hardest examples from both classes, whereas BCWF_s removes a larger number of harder and easy examples simultaneously for final balanced-class retention. Consequently, the well-trained T predictive classifiers can be used with two ensemble voting strategies: average probability and majority vote. To evaluate the proposed approach, we conduct intensive experiments on 10 benchmark data sets and apply our algorithms to perform default user detection on a real-world peer to peer lending data set. The experimental results fully demonstrate the effectiveness and the managerial implications of our approach when compared with 11 competitive algorithms. History: Accepted by Ram Ramesh, Area Editor for Data Science & Machine Learning. Funding: This work was supported by the National Natural Science Foundation of China [Grants 72101176, 71722005, and 72241432], the National Key R&D program of China [Grant 2020YFA0908600] and the Natural Science Foundation of Tianjin City [Grant 18JCJQJC45900]. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplemental Information (https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2023.1274) as well as from the IJOC GitHub software repository (https://github.com/INFORMSJoC/2021.0104) at (http://dx.doi.org/10.5281/zenodo.6360996). [ABSTRACT FROM AUTHOR]

Water films probably form beneath less-permeable interlayers in liquefiable deposits during an earthquake, further resulting in devastating disasters. However, the development of such water film and its effect on the liquefaction behavior of stratified deposits are still unclear. Herein, a water sedimentation method was developed in laboratory to reproduce the layered structure of sandy soil deposited in water during land reclamation. Undrained cyclic torsional shear tests were conducted to visualize the evolution of localized liquefaction behavior incorporating an image-based measurement technique. The test results indicate that the liquefaction resistance of layered specimens with less-permeable fine layers was similar to that of specimens without fine layer, which was possibly due to the lower liquefaction resistance of the sand layer compared to the fine layer. Large local strains periodically observed at the bottom of fine layer during undrained cyclic shearing implied that pore water concentrated into thin zones, which was also directly proven by the differential pore pressures in the sand and fine layers within the layered specimen. Moreover, large local strains also manifested a relatively lower liquefaction resistance of specimen compared to that evaluated by global strains. As specimen was closely liquefied, a hydraulic gradient significantly higher than its critical value to drive upward particle migration was formed at the fine layer, which overcomes the resultant force of gravity and buoyancy acting on soil particle. This hydraulic gradient and the less-permeable fine layer provided the formation conditions of a subjacent water film. [ABSTRACT FROM AUTHOR]

Falling film flow and heat transfer are extensively encountered in various industries of renewable and sustainable energy due to the outstanding heat transfer performance. The predictions in falling film hydrodynamics and heat transfer are crucial for the optimal design of falling film heat exchangers, and there have been considerable advancements made in this area over the past few decades. Considering the gaps in current literature predictions, this paper aims to present a comprehensive review on the correlations of flow pattern transition, film thickness, heat transfer, and liquid film rupture within falling film flowing over horizontal tubes and tube bundles. Through comparisons and summarizations, it can be found that the documented correlations appear to be significantly out of alignment with one another, which greatly restricts the applicability of these predictions. The correlations of falling film thickness that are obtained using regression approach based on dimensional analysis may take into account more factors than the ones modified from Nusselt theory. The predictions of flow pattern transition of falling liquid film with horizontal column are often described as the functions of the film Reynolds number, derived from the Kapitza number or the Galileo number. The functions of Nusselt number, film Reynolds number, Prandtl number, and Archimedes number are typically used to represent sensible and evaporative heat transfer correlations, whereas boiling heat transfer correlations also take into account the influence of heat flux, such as Boiling number. The full process of actual heat transfer is taken into account from both the standpoints of sensible convection and nucleate boiling using the combination functions of various heat transfer forms. Within the ranges of their own parameters, the well-established heat transfer models often offer good accuracy. While the predictions of phase change heat transfer often behave worse, the predictions of sensible heat transfer are more general and accurate. Generally speaking, the minimum film flow rate or the maximum heat flux were the functions that correlated with the inceptions of liquid film rupture. • Provides a comprehensive review of predictions for falling film hydrodynamics and heat transfer. • Describes in fully the most recent advancements in the relevant correlations. • Reviews respectively heat transfer prediction of sensible convection, evaporation, and boiling. • Provides an entire review of falling film heat transfer from subcooled convection to film dryout. • Proposed some recommendations and improvements for future research. [ABSTRACT FROM AUTHOR]

Falling film technology has been widely applied in various industrial processes, but vapor shearing effects cause significant problems. The mechanism by which vapor affects the hydrodynamics of a falling film has not yet been fully understood, particularly for cross vapor streams. In this paper, a three-dimensional model is developed to investigate the hydrodynamics of a falling film on a horizontal tube with a cross vapor stream. The results indicate that (1) there are valley and peak zones during the spreading of the liquid film; (2) the effect of cross vapor flow on the hydrodynamics of the falling film depends on the film flow rate, the cross vapor velocity, and the position on the tube; (3) with increasing vapor velocity, the peripheral film thickness increases on both the upwind and downwind sides for values of z* (the dimensionless axial coordinate) from 0 to 0.1, while decreasing on the upwind side but increasing on the downwind side for values of z* from 0.2 to 0.5; and (4) under the action of the cross vapor stream, liquid film offset occurs, characterized by the formation of new stagnation and detachment zones on the downwind side of the tube. [ABSTRACT FROM AUTHOR]

[Display omitted] • Summarise and redefine the photothermal catalysis. • Illustrate the three modes of photothermal catalysis: light-assisted thermocatalysis, heat-assisted photocatalysis, and light-driven thermal catalysis. • Discuss the future limitations and challenges, and highlight potential research directions and priorities. The elimination of air pollutants has garnered significant attention, particularly due to the strengthening of environmental protection. Photothermal catalysis (PTC) blends effective thermal catalysis with green photocatalysis, thus offering a remarkably eco-friendly approach to air pollutant treatment. Consequently, it has become a prominent and active research topic. The objective of this review is to offer a comprehensive analysis of the origins, advancements, recent developments in PTC, along with an exploration of its potential use cases. Concerning the activation energy source and the nature of catalytic action, PTC can be classified into three specific categories: light-assisted thermocatalysis, heat-assisted photocatalysis, and light-driven thermocoupled catalysis. This review methodically explores the catalytic mechanisms involved in each type. Furthermore, this review presents strategies for the design of exceptional photothermal catalysts, discusses the current challenges facing this field, and points out future research directions. [ABSTRACT FROM AUTHOR]

• Numerical study on falling film flow and heat transfer on porous tubes. • Compared falling film flow and heat transfer on plain and porous tubes. • Studied porosity, layer thickness, and material effects on flow and heat transfer. • Porous layer leads lower flow, thinner film, fewer rupture, better heat transfer. • Smaller porosity, thicker layer, aluminum and copper facilitate heat transfer. Porous surfaces often exhibit exceptional performance in liquid spreading and heat transfer, making them promising candidates for enhancing falling film heat transfer on solid surfaces. This paper delves into the flow and heat transfer characteristics occurring within falling films on horizontal tubes coated with a porous layer. To achieve this, a three-dimensional numerical model that couples the Volume of Fluid (VOF) method with porous media considerations was employed. The investigation comprehensively covers film spreading behavior, flow patterns, film velocity, film thickness, temperature distribution, and heat transfer coefficients, for both plain and porous tubes. Furthermore, we delve into the effects of key parameters, such as porosity, layer thickness, and material properties, on the overall heat transfer process. The results demonstrate the accuracy of our model in reproducing film thickness and heat transfer coefficients within falling films on horizontal porous tubes. When comparing plain tubes to porous ones, some key differences emerge. Specifically, the liquid film on porous tubes spreads more slowly, leading to increased film thickness and fewer occurrences of dry patches. Additionally, porous tubes result in lower film velocity and a more uniform temperature field compared to plain tubes. Interestingly, the findings reveal that smaller porosities yield thicker films and higher heat transfer coefficients, particularly when the porosity is below 0.4. Moreover, thicker porous layers result in thinner films, higher wetting ratios, and increased heat transfer coefficients. Among the materials we tested, aluminum and copper porous layers exhibit the highest heat transfer performance, while steel demonstrates the lowest. [ABSTRACT FROM AUTHOR]

• Thoroughly studied the variables affecting falling film dehumidification on corrugated plates. • Provided the optimum shape of the corrugated plate for falling film dehumidification performance. • Proposed a mass transfer correlation based on the current numerical data. • Clarified the enhancement mechanism of the corrugated surface for falling film dehumidification. Due to a number of benefits, liquid desiccant dehumidification has received a lot of attention lately. In comparison to previous improvement strategies, corrugated plates have demonstrated higher efficacy in liquid desiccant dehumidification. This study employs computational fluid dynamics to examine the dehumidification performance of falling film liquid desiccant dehumidification on over sinusoidally shaped corrugated plates. The effects of plate geometries, solution parameters, and moist air (concentration of humidity, temperature, and flow rate) were discussed. Additionally, a mass transfer correlation was proposed based on the current numerical data. It is indicated that the corrugated plate significantly enhances dehumidification performance due to the liquid film waves intensification, mass transfer area expansion, and induction of vortexes close to the gas-liquid interface. The most effective falling film dehumidification is achieved using a corrugated plate with a wavelength of 5.0 mm and an amplitude of 0.5 mm. By raising the solution or air inlet temperature, the dehumidification rate is reduced while being strengthened by raising the solution or air inlet concentration, velocity, or air humidity. While decreasing when solution intake concentration or air velocity rises, the efficacy of dehumidification rises as solution velocity does. The proposed mass transfer correlation accurately predicts 93.3 % of the 45 data, with an error of 11 % or less. In the current parameter scopes, the magnitude has a more significant effect on Sh air than the wavelength. Adjustments to air velocity and solution concentration can cause significant fluctuations in Sh air , while air and solution temperature have little effect on Sh air. [ABSTRACT FROM AUTHOR]

The peripheral heat transfer correlation of the subcooled falling liquid film outside the horizontal tube was established using the present numerical data under different liquid flow rates, heat fluxes, tube sizes, distributor heights, and liquid temperatures. The results indicated that the present correlation can predicate 93% of 2654 data within ±25% in θ = 2°–15°, 92% of 2254 data within ±15% in θ = 15°–165°, and 80% of 1442 data within ±30% in θ = 165°–178°. The peripheral heat transfer correlation can predict 74% of 903 data and 80% of 700 data, respectively, within 0°–180° and 15°–165° with the deviations of ±30%. The sensitivity analysis indicated that the parameter angle and the distributor height have the most and least significant impact on the peripheral heat transfer correlation, respectively. [ABSTRACT FROM AUTHOR]

In previous studies, particles, such as ellipsoids and super-ellipsoids, are mainly described by implicit functions. However, parametric functions can define more surfaces that can be used to represent a wider variety of particle shapes. In this study, parametric functions are used to construct particles, and the algorithm to determine the multi-point contact between concave particles is also given. Furthermore, the geometric parameters at the contact point, for instance, normal vectors, curvatures, and overlapping, are formulated by the parameters in the parametric function. To verify the proposed method, we use the discrete element method to simulate the systems of torus-shaped particles nested within each other, and analyze the momentum and kinetic energy changes with time. The equilibrium state with approximately zero energy is obtained, which means that the algorithm for multi-point contact of concave particles is suitable and stable. In addition to the torus-shaped particle, another two concave particles defined by parametric function are modeled. The simulation results indicate that the method is universal. Any plane curve can be used to construct surfaces by using the method provided in this work, and computational efficiency of simulations of particles defined by parametric function is higher because calculations of the inverse Jacobian matrix in the Newton-Raphson method are unnecessary. The parametric function method extends the scope of previous studies on particle shape. The falling process of suspended torus-shaped particles are shown in Figs. (a) and (b). Figure (a) presents the initial states of 270 particles. The final equilibrium state is shown in Fig. (b). The final residual velocity is less than 10−4 m/s, which meets the criterion of equilibrium state described by a previous study. [Display omitted] • A general method of constructing particles by parametric functions is provided. • The algorithm to determine the multi-point contact between particles is given. • The geometric parameters at the contact point are formulated. • We simulate the systems of torus-shaped particles nested within each other. • We simulate another two concave particle systems defined by parametric function. [ABSTRACT FROM AUTHOR]

[Display omitted] • Activation of surface lattice oxygen could be achieved by structure optimization. • More active surface lattice oxygen is exposed on Co 3 O 4 (1 1 2) planes. • Active surface lattice oxygen promotes the ring-open process in toluene oxidation. Co 3 O 4 catalysts with active surface lattice oxygen were constructed via a simple solvothermal method by adopting isopropyl alcohol (IPA) or tert -butyl alcohol (TBA) as solvent. The obtained Co 3 O 4 -IPA and Co 3 O 4 -TBA exhibit flower-like structures with (1 1 2) planes exposed on the surface. Due to abundant unsaturated Co3+ sites existing on the (1 1 2) plane, the content and activity of surface lattice oxygen on Co 3 O 4 -IPA and Co 3 O 4 -TBA are much higher than that on Co 3 O 4 -MA and Co 3 O 4 -EA, which prepared with methyl alcohol or ethyl alcohol as a solvent. The robust surface lattice oxygen on Co 3 O 4 -IPA and Co 3 O 4 -TBA facilitates the ring-opening process during photothermocatalytic oxidation of toluene, significantly promoting the catalytic performance. In the static atmosphere, about 98% of toluene conversion and 80% of CO 2 yield can be achieved on Co 3 O 4 -IPA and Co 3 O 4 -TBA under full-spectrum light irradiation of 325 mW/cm2, much higher than 89% and 73% of conversion, 50% and 26% of CO 2 yield on Co 3 O 4 -EA and Co 3 O 4 -MA, respectively. [ABSTRACT FROM AUTHOR]

The major difference between convex and concave particles is that more than one contact point can be found between concave particles. The existence of a multi-point contact introduces difficulties in determining each point. Another difficulty in modeling concave particles is that the normal vectors of two concave particles at the contact point are not always parallel, thereby causing differences between the action and reaction forces. Given their concavity and local convexity, heart-shaped particles are used to simulate a concave particle system. This work proposes a grid method for calculating the coordinates of each contact point. A novel data structure of multi-point contact and a searching point algorithm are also devised. Random packings under gravity and certain normal stresses are simulated to verify the validity of this method, and periodic frictionless systems are examined to find the closest packing. The validity of this method is proven by its numerical stability and convergence, and simulations of super-ellipsoid and torus particle systems attest of the universality of this method for different-shaped particles. Packing under normal stresses of 1and 10 kPa. (a) Initial state, and (b) equilibrium state. The coordination number is 8.284, whereas the volume fraction is 0.6266. Unlabelled Image • A novel grid method is proposed to calculate the coordinates of each contact point. • A new data structure and a searching point algorithm are also devised. • The processes of multi-point collisions are simulated to validate this method. • Random packings under gravity and certain normal stresses are simulated. • Periodic frictionless systems are examined to find the closest packing. [ABSTRACT FROM AUTHOR]

N,N'-dimethyl-N,N'-dioctyl diglycolamide (DMDODGA) in 40/60 (V/V)% 1-octanol/kerosene was used to extract 14 lanthanides from nitric acid solution. The effects of the aqueous acidity, the DMDODGA concentration, and the temperature on the distribution ratio of Ln(III) were investigated. The extraction equilibrium constants K and the thermodynamic parameters were determined by the slope analysis method combined with Pitzer model. The IR spectra of the extracted species and pure extractant were recorded and analyzed. Moreover, 0.001 mol/L nitric acid is the suitable stripping agent, and the stripping efficiency of all lanthanides can reach up 90% by three times of stripping. [ABSTRACT FROM AUTHOR]

A series of undrained cyclic torsional shear tests was conducted to investigate the development of local deformations of silica sand specimens directly using an image-based technique and a transparent membrane. The results for saturated sand specimens with varying densities showed that the vertical slippage of sand particles relative to the membrane was initiated at the liquefaction stage. Additionally, the quantity of vertical slippage of dense specimens was lower than that of loose specimens tested under the same conditions. Moreover, measured on the surface of the specimen, the large accumulated movement during cyclic shearing significantly increased the potential for inducing vertical slippage. A comparison of local deformation among the different tests revealed that the threshold of shear strain to generate non-uniform local deformations decreased with an increase in the relative density of the specimen. A lower liquefaction resistance layer, which formed at the upper part of the specimen after initial liquefaction, would accelerate the concentration of local shear strain; this was especially distinct when the specimen was completely liquefied. [ABSTRACT FROM AUTHOR]

• Tested cross vapor effect on the falling film evaporation of low pressure refrigerant. • Conducted larger vapor velocity effect on falling film evaporation in tube bundle. • Compared the cross vapor effect on falling film evaporation of R123 and R134a. • Visualized the cross vapor effect on falling liquid film flow and heat transfer. The falling film evaporation and the effect of cross vapor stream in falling film evaporator with triangular tube bundle using R123 was experimentally investigated. The variations of local and bundle average heat transfer coefficients were described. The tube bundle consisted of 4 × 3 (column × row) of triangular horizontal copper tubes. The tests without vapor effect were conducted with nominal heat fluxes of 20 to 60 kWm–2, saturation temperatures of 6 to 16 °C and film flow rates of 0.016 to 0.18 kgm–1s–1. Cross vapor stream effect experiments were operated at three heat fluxes of 20, 30 and 40 kWm–2 and two film flow rates of 0.035 and 0.07 kgm−1s−1, and the vapor velocity at the narrowest interstice in the tube bundle varies from 0 to 5.0 ms−1. It is indicated that the heat transfer is seriously influenced by the bundle effect while less affected by changing of saturation temperature. With the increase in vapor velocity, the heat transfer performance is generally weakened; the cross vapor stream has a strong influence on falling film evaporation of R123. [ABSTRACT FROM AUTHOR]

Background: The objectives of this study are to test the psychometric properties of the safety attitudes and safety climate questionnaire Chinese simplified version (SAQ-CS), to test the safety attitudes of health professionals in tertiary hospitals in the Liaoning province and to explore the effects of demographic factors on safety attitudes.Methods: The SAQ-CS was used to conduct a cross-sectional survey in nine tertiary hospitals in Liaoning province.Results: Cronbach's alpha of each subscale of SAQ-CS were > 0.7, the values of GFI, TLI, and CFI were > 0.8, and RMSEA values ranged from 0.048-0.199. The mean of the safety attitudes of 2157 health professionals was 4.00, indicating a good safety attitude, with a positive response rate (% of items that scored ≥4) of 51.1%. The stress recognition subscale had the lowest score, with a mean of 2.73 and a positive response rate of 17.8%. A multiple linear regression equation revealed that demographic factors like gender, age, and training participation significantly affected the scores (βgender > 0.06, βage < - 0.08, βtraining < - 0.07, p < 0.05).Conclusions: The psychometric properties of SAQ-CS are good and stable. Health professionals rate teamwork climate, safety climate, perception of management, and work conditions in Liaoning province are perceived as good; however, the stress of the health professionals is poor. To improve safety attitudes, it is necessary to not only reduce the stress of health professionals, but also to pay more attention to men, older health professionals, and health professionals who have not participated in safety training. [ABSTRACT FROM AUTHOR]

A simple, practical and gram-scale process for direct transformation of primary alcohols or silyl ethers to ammonium salts was developed. This method has the feathers of easy work-up (a simple filtration), mild condition, high yield, great practicality and robustness. And the application of the ammonium salts in Suzuki coupling reaction was also accomplished. Image 1 • A simple, practical and gram-scale process for direct transformation of alcohols or silyl ethers to ammonium salts. • Easy work-up (a simple filtration), mild condition, high yield, great practicality and robustness. • Application of the ammonium salts in Suzuki coupling reaction. [ABSTRACT FROM AUTHOR]

Highlights • A simple crop model, called SIMPLE, was developed including 13 parameters to specify a crop type, with four of these for cultivar characteristics. • Commonly available inputs that are required for the SIMPLE model include daily weather data, crop management, and soil water holding parameters. • The initial SIMPLE model was calibrated for 14 different crops from 25 detailed field experiments resulting in a RRMSE of 25.4% for final yield. Abstract Crop models are important tools for assessing the impact of climate change on crop production. While multiple models have been developed over the past decades for the major food and fiber crops such as wheat, maize, soybean, rice, and cotton, there are few or none for many other crops. The goal of this study was to develop a simple generic crop model (SIMPLE) that could be easily modified for any crop to simulate development, crop growth and yield. The crop model SIMPLE includes 13 parameters to specify a crop type, with four of these for cultivar characteristics. Commonly available inputs that are required for the crop model SIMPLE include daily weather data, crop management, and soil water holding parameters. The initial SIMPLE model was calibrated and evaluated for 14 different annual crops using observations for biomass growth, solar radiation interception, and yield from 25 detailed field experiments for a total of 70 treatments from 17 sites, resulting in a RRMSE of 25.4% for final yield. A sensitivity analysis comparing a C3, C4 and a legume crop showed an expected response to a gradual increase in temperature and atmospheric CO 2 concentrations. A regional gridded simulation for US potatoes reproduced the general observed patterns of spatial yield variability. Because the model is simple, it has several limitations, including the lack of response to vernalization and photoperiod effect on phenology. The model includes water, but no nutrient dynamics. However, an advantage of the model simplicity is that it can be easily adapted and evaluated for any new crop, based on literature data and field experiments, or general crop data such as sowing and harvest dates and yield statistics. The model is available in several simulation frameworks including a stand-alone version in R, Excel and as part of DSSAT. [ABSTRACT FROM AUTHOR]

A practical Pd‐catalyzed direct dehydroxylative coupling of (hetero)benzylic alcohols with (hetero)arylboronic acids for the constructions of di(hetero)arylmethane derivatives under SO2F2 was described. This new method provided a strategically distinct approach to di(hetero)arylmethane derivatives from readily available and abundant benzylic alcohols under mild condition. [ABSTRACT FROM AUTHOR]

Abstract Sulfur (SVI) based moieties, especially, the sulfonyl or sulfonamide based analogues have showed a variety of pharmacological properties, and its derivatives propose a high degree of structural diversity that has established useful for the finding of new therapeutic agents. The developments of new less toxic, low cost and highly active sulfonamides containing analogues are hot research topics in medicinal chemistry. Currently, more than 150 FDA approved Sulfur (SVI)-based drugs are available in the market, and they are widely used to treat various types of diseases with therapeutic power. This comprehensive review highlights the recent developments of sulfonyl or sulfonamides based compounds in huge range of therapeutic applications such as antimicrobial, anti-inflammatory, antiviral, anticonvulsant, antitubercular, antidiabetic, antileishmanial, carbonic anhydrase, antimalarial, anticancer and other medicinal agents. We believe that, this review article is useful to inspire new ideas for structural design and developments of less toxic and powerful Sulfur (SVI) based drugs against the numerous death-causing diseases. Graphical abstract Image 1 Highlights • More than 150 sulfonamide drugs are available in the market. • Sulfonamide based drugs are huge range of therapeutic applications. • We collected 337 potent bioactive sulfonyl or sulfonamide bearing heterocyclic analogues. • We briefly explain the structure activity relationship of all molecules to develop novel drugs. [ABSTRACT FROM AUTHOR]

Highlights • A LD pumped 1347 nm laser with Nd:GdNbO4 is realized. • Theoretical simulations under 808 nm and 879 nm pumping are conducted. • Direct pumping is utilized to achieve efficient 1347 nm laser output. Abstract A diode-pumped 1347 nm laser with a novel Nd:GdNbO 4 crystal is demonstrated for the first time to our best knowledge. Laser performance around 1.3 μm under 879 nm laser diode pumping is investigated with different output mirrors, pump radii and repetition rates. A maximum average power of ∼ 373 mW at 1347 nm is achieved at 50 Hz, corresponding to an optical-to-optical efficiency of 5.5% and a slope efficiency of 6.8%. [ABSTRACT FROM AUTHOR]

The violent vibration and excessive settlement of trackbeds under high-speed train moving loads are the main problems of ballasted tracks encountered in practice, which limits the rise of operation speed for ballasted railways. To date, the possibility of extending the widely used geogrid in conventional ballasted railways to high-speed railways has not been adequately validated. The stabilization mechanism of geogrids under high-speed train moving loads remains unclear. Herein, a ballasted track DEM model containing five sleepers that reproduced high-speed train moving loads was developed through EDEM software and validated by full-scale model tests. Both cases of ballasted tracks with and without the geogrid were examined. The results showed that the geogrid significantly decreased the total and differential settlement of the ballasted track. After geogrid installation, the coordination number of ballast particles was increased, and the contact forces among ballast particles were reduced, which potentially lowered the ballast breakage. The geogrid effectively constrained the displacement and rotation of ballast particles. The reduced migration of ballast particles led to a smaller and more uniform volumetric strain field of the ballasted trackbed. By investigating the working mechanism of the geogrid, it was shown that the penetration of the ballast particles into the geogrid aperture induced the expansion of the geogrid aperture, and therefore, the lateral force from the geogrid ribs limited the movement of the ballast particles. [ABSTRACT FROM AUTHOR]

The influence of downward vapor stream on the falling film evaporation with nucleate boiling outside a horizontal enhanced tube bundle arrayed in a vertical column is experimentally investigated. The variations in local and bundle averaged heat transfer coefficients with vapor velocity are presented. To simulate the practical condition in a falling film evaporator, the flow passages of the liquid/vapor are constructed using two quartz glass sheets and two columns of dummy half tubes. The test ranges are saturation temperature of 6 °C, film flow rate of 0.035–0.1 kgm –1 s –1 , heat flux of 20, 30, 40 kWm –2 . It is found that (1) the downward vapor effects are either positive or negative depending on the tube position, film flow rate, heat flux and vapor velocity; (2) the bundle effect becomes stronger under the effect of downward vapor stream; (3) the downward vapor has a significant effect on the heat transfer of the lower tubes than the upper tubes; and (4) the vapor stream effect on the bundle averaged heat transfer coefficient varies with the levels of film flow rate and heat flux. The experimental results provide significant guidance in the design of the vapor escape channel in a falling film evaporator. [ABSTRACT FROM AUTHOR]

The falling film evaporation of R134a with nucleate boiling outside a triangular-pitch (2-3-2-3) tube bundle is experimentally investigated, and the effects of saturation temperature, film flow rate and heat flux on heat transfer performance are studied. To study the effect of cross vapor stream on the falling film evaporation, a novel test section is designed, including the tube bundle, liquid and extra vapor distributors. The measurements without extra vapor are conducted at the saturation temperature of 6, 10 and 16°C, film Reynolds number of 220 to 2650, and heat flux of 20 to 60 kWm−2. Cross vapor stream effect experiments are operated at three heat fluxes 20, 30, and 40 kWm−2 and two film flow rates of 0.035 and 0.07 kgm−1s−1, and the vapor velocity at the smallest clearance in the tube bundle varies from 0 to 2.4 ms−1. The results indicate that: film flow rate, heat flux and saturation temperature significantly influence the heat transfer; the cross vapor stream either promote or inhibit the falling film evaporation, depending on the tube position, film flow rate, heat flux and vapor velocity. [ABSTRACT FROM AUTHOR]

The effects of film flow rate, heat flux, inlet liquid temperature, tube diameter and liquid distributor height on subcooled falling film heat transfer outside a horizontal smooth tube are numerically studied, and a heat transfer correlation based on the current data is developed. Comparisons between the predicted results and the published experimental data in the literature are also conducted. The calculation ranges are: film flow rate from 0.025 to 0.284 kg m −1  s −1 , heat flux from 1.0 to 100 kW m −2 , inlet liquid temperature from 2 to 104 °C, tube diameter from 6.35 to 50.8 mm and liquid distributor height from 3.0 to 50.8 mm. The results indicate that: (1) the numerical results of the local heat transfer coefficient are in good agreement with the experimental data in the literature; (2) the surface tension plays an important role in the calculations of heat transfer in two stagnation zones, (3) the heat transfer coefficient shows four distinct zones along with peripheral angle: stagnation zone, impingement zone, thermal layer development zone and departure zone; (4) the heat transfer coefficient increases with increase in film flow rate, tube diameter or liquid distributor height, while keeps constant with increasing heat flux; (5) the correlation predicts 92% of the total 141 calculated data with deviations within ±10%, and predicts 78% of 284 data available in literature with deviations within ±30%. [ABSTRACT FROM AUTHOR]

Besides normal and tangential forces, rolling and sliding are also important interactions of particles, and should be considered in the discrete element method. However, there are various definitions of rolling and sliding, some of which are quite different and even contradictory. On the premise of trying not to use definitions, the rolling and sliding velocities between non-spherical particles are derived, and satisfy the objectivity. The sliding and rolling velocities between spherical particles are included in the results as a special case. A rolling resistance model calculated by the rolling velocity is applied to simulate direct shear tests of non-spherical particles. In addition to coinciding with experiments, the shear curves also satisfy the rate independent theory. As a demonstration of the model’s universality, the wave propagation in uniaxial compression tests is also simulated. [ABSTRACT FROM AUTHOR]

Context:The defatted seeds ofCamellia oleiferavar.monospermaHung T. Chang (Theaceae) are currently discarded without effective utilization. However, sapogenin has been isolated and shows antioxidative, anti-inflammatory and analgesic activities suggestive of its neuroprotective function. Objective: In order to improve the activities of sapogenin, the nanoparticles of iron–sapogenin have been synthesized, and the neuroprotective effects are evaluated. Materials and methods:Structural characters of the nanoparticles were analyzed, and the antioxidant effect was assessed by DPPH method, and the neuroprotective effect was evaluated by rotenone-induced neurodegeneration in Kunming mice injected subcutaneously into the back of neck with rotenone (50 mg/kg/day) for 6 weeks and then treated by tail intravenous injection with the iron–sapogenin at the dose of 25, 50 and 100 mg/kg for 7 days. Mice behaviour and neurotransmitters were tested. Results:The product had an average size of 162 nm with spherical shape, and scavenged more than 90% DPPH radicals at 0.8 mg/mL concentration. It decreased behavioural disorder and malondialdehyde content in mice brain, and increased superoxide dismutase activity, tyrosine hydroxylase expression, dopamine and acetylcholine levels in brain in dose dependence, and their maximum changes were respectively up to 60.83%, 25.17%, 22.13%, 105.26%, 42.17% and 22.89% as compared to vehicle group. Iron–sapogenin nanoparticle shows significantly better effects than the sapogenin. Discussion and conclusion:Iron–sapogenin alleviates neurodegeneration of mice injured by neurotoxicity of rotenone, it is a superior candidate of drugs for neuroprotection. [ABSTRACT FROM AUTHOR]

The [(dppe)RhCl]-catalysed ring expansion of 2-methylbenzocyclobutenone has been proposed to occur by C−C oxidative addition to rhodaindanone, β-hydride elimination, hydrorhodation and C−C reductive elimination. DFT calculations [IEFPCM(1,4-dioxane, 383.15 K)/PBE0/DGDZVP level of theory] here confirm this mechanism. As proposed, oxidative addition into CHMe−CO bond is preferred over the alternative CHMe-aryl insertion. The barriers of oxidative addition, β-hydride elimination hydrorhodation, and reductive elimination are 23.6 (rate-determining), 8.9, 10.4, and 13.1 kcal mol−1, respectively. Therefore, the β-hydride elimination/hydrorhodation steps to/from an octahedral RhIII-hydride serve as a fast equilibrating hydrogen shuffle flanking the two slower C−C bond breaking/making steps. This is consistent with the weak kinetic isotope effect observed experimentally when 2-CH3 and 2-CD3benzocyclobutenone react competitively in a 1:1 ratio. The reaction barriers calculated with more modern, dispersion interaction-corrected methods (SMD/M06 and IEFPCM/ωB97xD) follow identical trends. [ABSTRACT FROM AUTHOR]

Soft soils beneath transportation infrastructures suffer dynamic traffic loads with high-frequency and high-cycle characteristics, which mainly present shakedown development of deformation yet probably induce notable deformation at the stable state. However, conventional constitutive models are still not available for the long-term behavior description of soft soils under high-cycle traffic loading. Herein, a conceptual model for high-cycle, low-amplitude undrained loading was proposed incorporating a shrinking yield surface and an expanding boundary surface, which individually indicated the weakening behavior caused by an increase in excess pore water pressure and the hardening effect due to contractive plastic deformation. Given the shakedown responses of soft soils, a mapping ratio and a one-time calculation approach were employed. Thus, the effect of loading frequency on the response of soft soil can be considered, and the calculation efficiency was greatly improved. Then, the evaluation of model parameters and parametric analyses on the loading frequency, shrinking yield surface, expanding boundary surface and mapping ratio were carried out to examine the performance of the proposed model. To further validate the proposed model, undrained cyclic triaxial tests on reconstituted Ningbo clay were conducted, and high-cycle undrained triaxial tests on Kaolin clay and Ariake clay were referenced. The predicted developments of accumulated plastic deviatoric strain and excess pore water pressure with the number of load cycles reached acceptable consistencies with the experimental results. Moreover, the effects of confining and deviatoric stresses were investigated. Not only rational developments of excess pore water pressure and plastic deviatoric strain but also nearly identical results under the same cyclic stress ratio (CSR) were obtained, which adequately confirmed the feasibility and reliability of the proposed model. Although this model was developed based on isotropically consolidated soils and contained varied parameters for different CSRs, it provides a framework contributing to rigorous model development for high-cycle conditions. [ABSTRACT FROM AUTHOR]

In order to avoid damage during shield tunnel construction to adjacent buildings on the ground, it is of paramount importance to precisely predict the Maximum Surface Settlement (MSS) deformation induced by shield tunneling under the surface. In this paper, a hybrid algorithm model incorporating the Extreme Gradient Boosting (XGBoost) with the Golden-sine Seagull Optimization Algorithm (GSOA) is proposed, namely the GSOA-XGBoost model. A total of 323 datasets including torque, penetration rate, thrust, cutterhead rotation speed, slurry pressure, grouting pressure, cover depth, and distance between cutting face and monitored section are taken as input parameters, and the corresponding measured MSS deformation is adopted as the output parameter. This dataset is employed to train the MSS prediction algorithm model. The analysis results indicate that the proposed GSOA-XGBoost hybrid algorithm model is much superior to other models in terms of accuracy, stability and computation time, and strong correlations are discovered between the predicted and measured settlements. Our model can predict the MSS deformation caused by shield tunnel construction with higher reliability, strong robustness and fault-tolerant capacity, and greatly reduces the engineering risk. Simultaneously, the consistency of the slurry pressure and grouting pressure values is calculated by the SOA-XGBoost and the grid search method, which demonstrates the feasibility and rationality of proposed hybrid algorithm model. [ABSTRACT FROM AUTHOR]

• Establishment and verification of a rig for refrigerants' pool boiling. • Heat transfer coefficients were obtained for the R134a pool boiling on 6 surfaces with various roughness and wettability under 3 saturation temperatures. • A phenomenon of bubble behavior above the boiling surface was spotted and observed with a high-speed camera. In order to investigate pool boiling heat transfer characteristics of refrigerants on different surfaces, an experimental rig is established and verified in this study. The pool boiling heat transfer experiment is conducted with R134a at three saturation temperatures. Six surfaces with Ra roughness ranging from 0.133 to 5.742 μm and two types of wettability are tested in the study. The heat flux varies from 40 to 280 kW/m2. Experimental results indicate that higher roughness is favorable to boiling heat transfer. Shieldex coating on copper surfaces can deteriorate heat transfer by 20% approximately. Visualization analysis was carried out with a high-speed camera to study bubble behavior. A new-found mode of bubble departing was observed at lower heat flux. Besides, the data were correlated in the form of Rohsenow correlation, and comparison and supplement are concluded based on data obtained in this study. [ABSTRACT FROM AUTHOR]

Falling film evaporation is an efficient heat transfer mode in refrigeration and air conditioning industries. In this paper, the falling film evaporation performances of R134a and R123 outside four enhanced tubes and a smooth tube are tested. The results reveal that: with the decrease of film flow rate the falling film heat transfer coefficients of both R134a and R123 on the five tubes exhibit two general stages (a plateau stage and a sharp drop stage); for R134a the plateau is quite uniform while for R123 a mild decrease occurs with the decrease in film flow rate. The four enhanced tubes behave differently in heat transfer performances for R134a and R123. R134a provides around 2–3 times of heat transfer coefficients of R123 for all tubes. [ABSTRACT FROM AUTHOR]

• Studied numerically the falling film flow and heat transfer under turbulent regime. • Clarified the dominant factors tube bundle effect in the turbulent condition. • Compared fluid flow and heat transfer results between laminar and turbulent regimes. • Recommended the key parameters and factors for a higher heat transfer performance. Turbulent falling films are commonly encountered in the practical operations of most falling film applications, but the relevant numerical study is very scarce. The hydrodynamics and thermal performance of falling films in horizontal tube bundles under the turbulent regime were numerically investigated in this study. The calculation ranges are: film Reynolds number from 3505 to 8034, heat flux of 47.3 kWm−2, inlet liquid temperature of 46 °C, tube diameter of 19.0 mm and liquid distributor height of 6.4 mm. Based on the results of the present numerical model, the Standard k - ω model is more suitable in reproducing the falling film heat transfer profile, as the present numerical model accurately predicted the turbulent falling film heat transfer characteristics. There are various hydrodynamics depending on the bundle arrangement and flow regime, including splashing, bridging, gas entrainment, Coanda effect, and liquid film thickness. The triangular bundle provides the highest heat transfer coefficient, but the square bundle provides the poorest one, and the square and rotated-triangular tube bundles behave the largest and smallest bundle effect, respectively. The bundle effect is generally independent of film Reynolds number, liquid feeder height and tube spacing. [ABSTRACT FROM AUTHOR]

The rotation of a single particle plays a very important role in the simulation of granular flow through the discrete element method (DEM). Many researchers have noted that the effect of rolling resistance at the contact points should be considered in DEM simulations. The rolling resistance between particles, which is mainly introduced from the force or rolling deformation (velocity) between particles, is indicated in different models. However, various models cause different results. Hence, the most feasible model should be determined. For this purpose, five models are adopted to simulate the simple shear flow by DEM in this work. Simulation indicates that the contraction/dilatancy and force–displacement curves at different volume fractions are in good agreement with the experimental findings. The curves of Models 1 to 3 computed by force and angular velocity separate at different shear speeds, but this result does not satisfy the rate independent theory. The curves of Models 4 and 5, which are calculated by the rolling deformation, are better in keeping with the rate independence than the three previous models. After increasing the particle-size distribution, Model 5 appears to be more reliable. The defects of the four other models are discussed from the physical mechanism perspective. The force–displacement curves of Model 5 at a difference of 20 times in shear speed coincide perfectly. Overall, the findings satisfy both the objectivity and the rate independent theory. [ABSTRACT FROM AUTHOR]

• Reinforcing oil well cement using a hybrid of nano-silica (NS) and nano-hexagonal boron nitride (h-BN). • NS is a cement thickener, h-BN has little effect on rheology properties. • A hybrid of NS and h-BN can significantly improve the mechanical properties in the early stages. • The modification mechanisms of hybrid NS and h-BN in cement are discussed. The purpose of this study was to investigate the effect of the content of hybrid nano-silica (NS) and nano-hexagonal boron nitride (h-BN) on the rheological properties and early mechanical strength of oil-well cement using response surface methodology (RSM). Based on the microstructures revealed by X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy, the modification mechanism of cement mixed with a hybrid of NS and h-BN in the early stage of hydration was studied. It was found that the rheological properties of fresh oil-well cement slurries with added NS and h-BN conformed to those of Bingham fluids. An increase in NS content worsened the fluidity of the cement, whereas the h-BN content did not affect its fluidity. The early compressive, flexural, and splitting tensile strengths at the end of the 3-day curing time increased by 12.33 MPa/47.24 %, 1.88 MPa/29.01 % and 1.24 MPa/53.22 %, respectively. The pozzolanic reaction of NS begins to occur in the early stages of cement hydration. The synergistic effect of the added NS and h-BN increased the density of the early hydration product of the cement. The h-BN mainly enabled the bridging, filling, and crack-resistant effects in the early oil-well cement. [ABSTRACT FROM AUTHOR]

• Examined surface tension model effect on falling film flow on a horizontal tube. • Surface tension is indispensable in calculation of gravity-driven liquid film flow. • Given microscopic insights of falling film flow for different surface tension models. • Both CSF and CSS models can reliably reproduce the falling liquid film hydrodynamics. Computational fluid dynamics (CFD) modelling is extensively and successfully used for the reproduction of liquid film hydrodynamics. Surface tension significantly influences the numerical reproduction of falling liquid film flow. In this study, the hydrodynamics of the liquid film flow over a horizontal tube and a vertical plate is explored with different surface tension models. The results reveal that the neglect of surface tension leads to quantitative and qualitative distortions in the numerical simulation of the thin liquid film. Both continuum surface force (CSF) and continuum surface stress (CSS) models can produce the hydrodynamic behaviors of the falling film on the horizontal tube and the vertical plate, including pendant droplets, column necking or necking break, thickness of the film, vortex, liquid film detachment, as well as the values and trends of the velocity components. However, the CSF and CSS models produce different transient phase contours and streamlines, as well as different profiles of the time-averaged velocity components of the falling films on the horizontal tube and the vertical plate. Besides, there is no obvious difference between CSF and CSS in the perspective of time-averaged film thickness on a horizontal tube. [ABSTRACT FROM AUTHOR]

The three-point bending experiments on three-dimensional multiaxial warp-knitted carbon/epoxy composites with two fiber architectures are performed at room and elevated temperatures. Macro-fracture morphology and scanning electron microscopic micrographs are examined to understand the deformation and failure mechanism. The results show that the load–deflection curves are significantly different for different temperatures and the bending properties decrease significantly with increasing the temperature. Meanwhile, bending properties can be affected greatly by the fiber architecture and these increase significantly with the decrease of the fiber orientation angle at different temperatures. The results also show that the damage and failure patterns of composites vary with the test temperature. At room temperature, the composite exhibits brittle feature, and it damages with the breakage and tearing of fibers. At elevated temperature, the composite becomes more softened and exhibits plasticity. The damage of matrix plastic and cracking, interface debonding, and fiber layer delaminating become prominent. Moreover, the failure mechanism at room and elevated temperatures can be significantly affected by the fiber architecture. [ABSTRACT FROM AUTHOR]

The effect of vapor flow on the falling film evaporation of refrigerant R134a outside a horizontal tube bundle is investigated with an experimental approach. The test space is a cube with a rectangular cross section of 0.575 m (length) × 38.8 mm (width). The tube bundle was 3 × 6 (columns × rows) of staggered horizontal finned tubes made of copper. The longitudinal tube pitch is 22.5 mm and the transverse is 19.9 mm. The external fin density of test tube is 45 fpi (fins per inch), and outside diameter is 19.05 mm. The vapor flow velocity can be adjusted in the range of 0–3.1 m/s. Liquid falling film flow rate ranges from 0.07 to 0.2 kg/m·s. Experiment is firstly conducted at saturation temperature of 6 °C without the effect of additional vapor flow at the heat flux of 20, 60, 100 and 180 kW/m 2 (for the first tube row). Vapor flow effect experiment was carried out at three heat fluxes 20, 40 and 60 kW/m 2 . It is found that falling film flow rate is an important factor to influence the evaporating heat transfer coefficient. With the effect of vapor flow, both positive and negative effects are observed as the increment of vapor velocity. Positive effects are predominant for the two tubes in the top positions and higher vapor velocity. [ABSTRACT FROM AUTHOR]

In this article, we report a facile one-step synthesis of Ni@graphene nanocomposite microspheres (NGs) in hydrazine hydrate solution under ultrasound conditions. During the ultrasonic process, graphene oxide (GO) was reduced effectively under mild conditions and Ni nanoparticles were simultaneously formed and anchored on graphene sheets, which act as spacers to keep the neighboring sheets separated. The target products exhibit excellent performance for fast and efficient removal of dye contaminants, rhodamine B (RhB) in aqueous solution, under assistance of ultrasound. Finally, the nanocomposites can be easily separated from solution by a magnet. Furthermore, higher content of graphene can be produced under sonication, which facilitates faster and more efficient removal of organic contaminates in the solution. The nanocomposites were also characterized by scanning electron microscopy, Raman spectroscopy, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction and thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

Mud pumping that is deliberately avoided in the design of a ballastless high-speed railway still occurs and induces extraordinary track vibrations. In this study, in situ investigations and laboratory tests were performed to disclose the initiation and development of mud pumping detected in the field. The in situ investigations indicated that mud pumping principally appeared at both ends of the concrete base up to a maximum distance of 2 m. Precipitation, instead of groundwater, was found to be the water source triggering mud pumping; this infiltrated the graded gravel roadbed through the detachments of the ends of the overlying concrete bases due to the whipping effect. Once mud pumping occurred, the vibrations of concrete bases were aggravated and caused severe track settlements under train loads. The results of laboratory tests indicated that the infiltrated rainwater was retained in the roadbed above the less permeable subgrade, and the roadbed contained an unstable particle skeleton with excessive plastic fine particles, both of which provided favourable conditions to form mud pumping under dense high-speed train loads. Soil particles of less than 7·1 mm in diameter migrated during mud pumping; these first accumulated at the lower roadbed, then gradually migrated to the upper roadbed, actuated by the hydraulic gradient generated, and were finally pumped out through the detachments around the expansion gaps, thereby resulting in large amounts of voids in the roadbed and a vicious cycle if not treated in a timely fashion. These features of mud pumping in ballastless tracks differ from those of ballasted tracks and will benefit the development of remediation measures and improvement of slab track designs. [ABSTRACT FROM AUTHOR]

Discrete element method with different shapes has attracted considerable research attentions because particle shapes affect dynamic properties of the system. Although convex particles have been extensively investigated, studies on concave particles are limited. Cardioid particles are constructed in this study using parametric equation. Multi-point contact detection algorithm and calculation methods of geometric parameters, such as normal vector, curvature, and overlapping at the contact point, are provided. Two-dimensional (2D) and three-dimensional (3D) systems are simulated by using the discrete element method. Convergence of energy in falling process under gravity verifies the stability and correctness of the algorithm. On this basis, shear curves of simple shear tests with different shapes are calculated and propagation processes of elastic waves in uniaxial compression systems with periodic boundary conditions are simulated. Results showed that the particle shape affects not only shear strength of the simple shear system but also elastic wave velocity in the uniaxial compression system. The particle shape will cause anisotropies of normal vector of contact force, branch vector, and contact force distributions. Influence of shape on the wave velocity is explained from the perspective of anisotropy. The proposed method in this study is universal and suitable for other shapes defined by different parametric equations and can be used to investigate dynamic properties of particle systems with various shapes. [Display omitted] • Two-dimensional cardioid particles are constructed using parametric equation. • Three-dimensional surfaces are obtained by rotating 2D cardioids around the x -axis. • Multi-point contact detection algorithm is presented. • Calculation methods of geometric parameters are provided. • Influence of shape on the wave velocity is explained by the anisotropy. [ABSTRACT FROM AUTHOR]

A new small molecule with excellent electron-transporting property, namely 9,10-bis(2-( N-octyl-1,8-naphthalimid-4-yl)ethynyl)anthracene ( BNA), is prepared and characterized. A polymer solar cell ( PSC) based on poly(3-hexylthiophene) ( P3HT) and [6,6]-phenyl C61 -butyricacidmethyl ester ( PC61BM) is also fabricated by using BNA as the cathode buffer layer between the Al electrode and photoactive layer, and their influence on the performance of the PSCs is investigated. It is found that the open-circuit voltage ( V oc ), short-circuit current density ( J sc ), and power conversion efficiency ( PCE) of a device with a 6-nm BNA layer improved to 0.63 V, 9.74 mA/cm2, and 3.74%, respectively, which correspond to an increase of 53.6%, 38.0%, and 177% compared to those without the buffer layer. The BNA buffer layer could effectively improve the interfacial contact performance between the Al electrode and photoactive layer, decrease the series resistance, and improve the collection efficiency of carriers. The devices with appropriate thickness of the BNA buffer layer can also replace the common low-work-function metal Ca for increasing the PCE and lifetime of PSCs. [ABSTRACT FROM AUTHOR]

With increasing train speed and wheel axle load, severe vibrations can occur in a ballasted trackbed, thereby accelerating the degradation of the ballast particles and ultimately causing excessive settlement. To gain insights into the long-term trackbed behavior and the ballast degradation evolution, a full-scale ballasted track experiment with eight sleepers was designed and tested on a validated physical model test platform (ZJU-iHSRT). Sieving analysis together with computer-aided ballast morphology analysis were adopted to quantify the ballast degradation in terms of both the ballast particle size and morphological evolution, after every 100,000 train carriages. Various sensors were installed at key locations in the trackbed to record the dynamic stress responses, vibration velocities and deformations under train moving loads for up to 500,000 train carriages in total. The movements of individual particles inside the ballast layer were also captured using "SmartRock" wireless sensors. The dynamic soil stresses and vibration velocities in the trackbed all peaked at the locations underneath the rail seat and decayed with the distance away from the rail seat. Severe ballast degradation occurred in both particle sizes and morphological properties, with the ballast particles in the middle zone under the sleeper suffering a greater breakage due to the stronger confinement. The long-term train loads densified the ballast layer, both through particle rearrangement and particle breakage filling the voids in the ballast bed, resulting in a reduction in the stresses and vibrations. The amplitudes of the vertical stresses and the vibration velocities in the trackbed around the rail seat were reduced by over 25% and 38% respectively after 500,000 train loading carriages. The ballast particle shape became more compact after the test, with larger diameter and more Platy, Bladed and Elongate shapes found to be the more likely to degrade. Over 50% of the permanent settlement of the ballasted trackbed resulted from the ballast layer deformation, and the increase in the train speed intensified particle movements away from the sleeper in the lateral and longitudinal directions in the ballast layer and accelerated the development of the accumulated settlement, while the increase in the axle load caused the ballast breakage index (BBI) to rise dramatically by over 50% and contributed significantly to a greater settlement. • Train running at high speed significantly intensifies the ballast particle movement. • Heavier wheel axle load causes ballast breakage index (BBI) rose dramatically and contributed to a greater trackbed settlement. • The ballast shape class became more compact after the 500,000 passages of train carriages. • Ballast particles with platy, bladed and elongate shapes are prone to breake. [ABSTRACT FROM AUTHOR]

The tensile experiments on the three-dimensional (3D) multi-axial warp knitted (MWK) composites with four types of fiber architecture were performed at room and liquid nitrogen temperatures (as low as -196°C). Macroscopic fracture morphology and SEM micrographs both are examined to understand the deformation and failure mechanism. The results showed that the tensile properties can be affected greatly by the fiber architecture and these decrease significantly with the increase of the fiber orientation angle at room and liquid nitrogen temperatures. Meanwhile, the tensile properties at liquid nitrogen temperature have improved significantly than that of those at room temperature. Moreover, the damage and failure patterns of composites vary with the test temperature. At liquid nitrogen temperature, more microcracks appear and the brittle failure feature becomes more obvious; however, the interfacial adhesion capacity is enhanced significantly. In addition, the fiber architecture has remarkable effect on the failure mechanism at room and liquid nitrogen temperatures. [ABSTRACT FROM AUTHOR]

Abstract: Three-point bending tests at room and liquid nitrogen temperature (as low as −196°C) are conducted on the 3D integrated woven spacer composites with different core heights. Macrofracture morphology and SEM micrographs are examined to understand the deformation and failure mechanism. The results show that the bending properties at liquid nitrogen temperature are improved significantly than those at room temperature. Meanwhile, the bending properties both at room and liquid nitrogen temperature can be affected greatly by the core height. Moreover, the damage and failure patterns of composites vary with the core height and test temperature. At room temperature, three typical failure mechanism have been obtained for composites with different core heights. At liquid nitrogen temperature, the composites show gradual failure process which extends from the external layers of the compression face to the interior core layers. Furthermore, the brittle failure feature becomes more obvious and the interfacial adhesion capacity is enhanced significantly. [Copyright &y& Elsevier]

Highlights: [•] Obtain flat and warp compression properties of 3D integrated woven spacer composite. [•] The damage and failure mechanism is demonstrated under flat and warp compression. [•] Analyze the influence of core height on compressive properties and failure modes. [Copyright &y& Elsevier]

Abstract: The compressive experiments on the 3D braided composites with different braiding parameters are performed in three directions (longitudinal, in-plane and transverse) at room and liquid nitrogen temperature (low as −196°C). Macro-Fracture morphology and SEM micrographs are examined to understand the deformation and failure mechanism. The results show that the stress–strain curves and the compression properties are significantly different in the longitudinal, in-plane and transverse direction. Meanwhile, the compression properties at liquid nitrogen temperature are improved significantly than that at room temperature. Moreover, the damage and failure patterns of composites vary with the loading directions and test temperature. At liquid nitrogen temperature, the brittle failure feature becomes more obvious and the interfacial adhesion capacity is enhanced significantly. In addition, the compressive properties and failure mechanism at room and liquid nitrogen temperature can be significantly affected by the braiding angle and the fiber volume fraction. [Copyright &y& Elsevier]