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PurposeSince surface runoff clogs stormwater grates, leading to deterioration of drainage capacity, and also it is difficult to complete the study with actual dimensions in experiments, a numerical simulation work was established in this study to investigate the surface runoff clogging stormwater grate patterns. The purpose of this study is to describe the mechanisms of storm grate clogging and storm well deposition for different flow rate floods and granular materials.Design/methodology/approachIn the work of this study, the volume of fluid (VOF) method and the discrete element method (DEM) are used to solve the gas–liquid and particle flows. In order to solve the evolution of the gas–liquid interface during surface runoff, the VOF was used. To simulate the rain grate and set up different material particles to represent the surface floating materials, the DEM was utilized.FindingsThe research results show that the clogging distribution and clogging rate of the rainwater grate are closely related to the fluid flow velocity and the physical characteristics of the particles, and the higher the clogging rate of the rainwater grate and the higher the number of particles deposited in the rainwater well at the same surface runoff velocity, the higher the density of the clogged particles. The surface runoff velocity (0.5 m/s, 1 m/s) shows that the rapid change of particle movement state at high runoff velocity makes the particle clogging more obvious.Originality/valueA multi-scale CFD-DEM approach was used to simulate the particulate motion of the road surface with different incoming runoff velocities. The innovative use of DEM to model the storm grate simulation ensures the accuracy of the traction model.

An analytical method of microspheric brominated covalent organic framework (Br-COF)-online solid-phase extraction integrated with high-performance liquid chromatography (online SPE-HPLC) was proposed for efficiently enriching six polybrominated diphenyl ethers (PBDEs) in foods. The Br-COF microspheres were facilely prepared with uniformity and dispersion by a size-controllable synthesis at the room temperature. Attributed to multiple interactions of the halogen bonding, Van der Waals forces, hydrophobic interaction along with size-matching effect, Br-COF performed satisfactory extraction capacity for PBDEs compared with commercial adsorbents. Five primary influencing factors were optimized, including loading solvent, loading flow rate, elution solvent, elution flow rate and elution volume. Under the optimal parameters, the implement displayed excellent linear ranges (0.5-500 ng mL

To understand the effects of 'planting conifer and preserving broadleaved tree' and light-felling on the hydrological effects of litter layer during the restoration of the climax vegetation broad-leaved Korean pine forest in temperate zone of Northeast China, we measured litter accumulation, water holding process of litter, and maximum holding water, maximum blocking and effective blocking amount of litter layers using sample survey method and indoor immersion method in three forests (aspen-Korean pine forests, white birch-Korean pine forest, and Mongolian oak-Korean pine forest) under different light-felling intensity (control, C; low light-felling, L; moderate light-felling, M; heavy light-felling, H) in Xiaoxing'an Mountains. The results showed that the intensity of light-felling had different effects on litter accumulation (7.32 to 15.58 t·hm为了揭示“栽针保阔”及透光抚育在恢复东北温带地带性顶极植被阔叶红松林过程中对凋落物层水文效应的影响规律,采用样地调查法和室内浸泡法,同步测定小兴安岭山杨-红松林、白桦-红松林和蒙古栎-红松林(冠下栽植红松25～35年)在不同透光抚育强度(对照,轻、中、强度透光抚育)下的凋落物量、凋落物持水过程、最大持水量、最大拦蓄量和有效拦蓄量。结果表明: 透光抚育对3种林型凋落物蓄积量(7.32～15.58 t·hm

The flow characteristics and clogging laws of micro particles with different sizes on ground surface passing through porous infiltrated materials were investigated. Experiments with surface runoff plugging on porous infiltrated materials were conducted and analyzed, combined with coupled computational fluid dynamics - discrete element method (CFD-DEM) simulations. In the study, the standard quartz sand particles of less than 0.3 mm, 0.3–0.6 mm, 0.6–0.9 mm and 0.9–2.2 mm were selected for the permeable material clogging experiment. The CFD-DEM coupling model was verified by comparing it with the recorded permeability coefficient from the experiment. The seepage velocity, total force of the fluid and spatial distribution of particle with different sizes were analyzed in detail by the model, and the influence of the change of the particle position at different time on the blockage of permeable material was determined. The results of experiments and numerical simulations indicate that in the initial stage of seepage, the rapid formation of clogging of the particles in the surface layer leads to an evident decrease in the permeability coefficient. Due to the small pore structures of the porous permeable material, the particle with sizes from 0.6 to 2.2 mm are blocked within 2 cm of the surface layer, resulting in obstructing 0.3–0.6 mm particles in the wake. However, particles less than 0.3 mm can penetrate deep into the permeable material, and accumulate in the deep pores, eventually forming a deep blockage with evolution of time. The above results are also normalized with characteristic scales, and self-similarity existed in the clogging phenomenon are discovered. The whole research realizes the unification of experiment, numerical simulation, and dimensionless analysis, and it is believed that the obtained laws can provide guidance for further relevant studies on the plugging of pervious materials.

Selection of port enterprises logistics service providers is a complex multiple attribute decision-making problem. In order to improve the scientific nature of selection, a set of reasonable decision-making methods of logistics service providers selection are needed to establish. Accordingly, a combination weighting-grey synthetic decision-making method is proposed, which is used to solve the problem of providers selection. Firstly, this method combines the network analysis method with the entropy method to determine combined weights of evaluation indexes. Secondly, the improved center-point triangular whitenization weight function is introduced to cluster alternative plans and judge its corresponding grey classes, and then synthetic weighted decision-making vectors are used to solve grey synthetic decision-making coefficient vectors. Next, grey synthetic clustering decision-making coefficients are calculated to conduct a synthetic decision-making rank of alternative plans. Finally, an empirical study is conducted to verify the effectiveness of the proposed method by taking logistics service providers selection of a port enterprise.

In order to study the pore seepage and clogging problems in the permeable concrete, the permeable concrete blockage test device was used to simulate the flow law and distribution of the surface micro-particles through the concrete at the beginning of rainfall. The internal pore structure was reconstructed by CT scanning technique combined with avizo software. The DPM model in CFD was used to simulate the multiphase flow of Kunming surface microparticles through the permeable concrete. The results show: The results obtained by CFD numerical simulation are in good agreement with the experiment. The surface micro-particles with particle size range of 200-500um have a certain degree of blockage to concrete, and still have good water permeability (higher permeability coefficient), and after adding below 200um The particle clogging is more significant, and the permeability coefficient is basically close to 0; but more importantly, it is found by DPM simulation that the small particles of 0-100 um pass through the concrete and the seepage velocity is slow and the partial adhesion to the wall of the tunnel causes the diameter to decrease and affect the seepage.

Screw-thread steel, which is produced using the quenching process through wear water controlled rolling system, would prone to generate red rust on its surface. For this reason a combustion apparatus with a smoke backflow area containing partly unburnt combustible fuel is designed to study the rusted 20MnSi wear water screw-thread steel under high temperature flame hot melting. With SEM/EDS and XRD analysis we could affirm that the main composition of the red rust is Fe2O3It assumes loose, porous branches and leaves, therefore makes the absorption of water and gas easier and intensified the sprawling of corrosion. While the steel surface after hot melting treatment form a tight passivation layer made of Fe3O4and FeO, which would isolate outer circumstance thereby protects the metal body. In the article we analyzed two main reasons that cause the red rust and point out contents that requires further studies. Compared with using chemical addition agent, this high temperature flame hot melting reaction technique is beneficial to the environment while of lower cost.

Asthma is one of the most common chronic inflammatory disorders, associated with reversible airflow obstruction, airway hyperresponsiveness, and airway remodeling. This disease has a significant impact on individuals, their families, and society. Standardized therapeutics such as inhaled corticosteroid in combination with long acting β2 agonist have been applied for asthma control; however, complementary and alternative medicines, especially herbal medicines, are still widely used all over the world. A growing body of literature suggests that various herbals or related products might be effective in inhibiting asthmatic inflammation. In this review, we summarize recent advances about the mechanistic studies of herbal medicines on allergic airway inflammation in animal models and their potential application into clinic for asthma control.

Using plasma alloying technique, Q235 steel was firstly treated by W-Mo-Y Multi-elements co-diffusion followed by plasma nitriding process. And then the wear tests were conducted. The effects of technological parameters on alloying layer were studied. The structure, composition, phase and micro-hardness of alloying layer were analyzed by metalloscope, XRD, SEM and microhardness tester. Results show that the microstructure of W-Mo-Y Co-diffusion layer is columnar crystal; W, Mo contents decrease from the outside to the inside. The element Y is distributed mainly at the grain boundaries. The phase of alloying layer consisted of Fe, Fe3Mo, Fe17Y2and the solid solution of (W, Mo, Y) in α-Fe. After plasma nitriding process, the co-diffusion layer is strengthened and large amount of nitrides form and dispersedly distribute in the alloying layer. After nitriding the phase of alloying layer consist of Fe4N, Fe3Mo, Fe, MoN, Mo2N, W2N, WN. the average micro-hardness is 850HV0.05.Compared with untreated samples, the wear resistance of alloying layer is improved by 2 times under abrasive wear conditions.

Q195 steel was conducted by plasma chromizing and Cr-Ni surface alloying process to research the relationship between unit diffusion and binary diffusion. After studying the thickness, composition, phase component of the layer and diffusion coefficients of alloying elements, results showed that (1) the thickness of chromizing layer was 150μm; the surface phase component was Fe-Cr solid solution; the surface chromium contents was 21.4%. The thickness of Cr-Ni co-diffusion layer was 40μm; the surface phase component was Fe-Cr-Ni solid solution; the surface contents were: Cr 16.14%, Ni 48.16%. The alloying elements distributed in downward gradient from the outside to the inside. (2) Compared with plain surface alloying technique, using plasma surface alloying technique can get higher diffusing speed and shorten production cycle time. (3) The diffusion coefficients decreased as the diffusion distance increased. (4)Compared with chromizing, Cr-Ni co-diffusion increased the utilization ratio of alloying elements but decreased the diffusion speed of alloying elements, thus the surface alloying content increased and the thickness of alloying layer decreased.

Using plasma alloying technique, Q235 steel was firstly treated by W-Mo-Y Multi-elements alloying followed by plasma nitriding process. The effects of process parameters on alloying layer were studied. The structure, composition, phase and micro-hardness of alloying layer were analyzed by metalloscope, XRD, SEM and microhardness tester. Results show that the microstructure of W-Mo-Y alloying layer is columnar crystal, and W, Mo contents decrease from the outside to the inside. The element Y is distributed mainly at the grain boundaries. The phase of alloying layer consisted of Fe, Fe3Mo, Fe17Y2 and the solid solution of (W, Mo, Y) in α-Fe. After plasma nitriding process, the co-diffusion layer is strengthened and large amounts of nitrides form and dispersedly distribute in the alloying layer. The phase of alloying layer consist of Fe4N, Fe3Mo, Fe, MoN, Mo2N, W2N, WN. The average micro-hardness of alloying layer is 850HV0.05. And then the wear tests were conducted. Compared with untreated samples, the wear resistance of alloying layer is improved by 2 times under abrasive wear conditions.