Unique double-layer solid electrolyte interphase formed with fluorinated ether-based electrolytes for high-voltage lithium metal batteries

Li metal batteries using high-voltage layered oxides cathodes are of particular interest due to their high energy density.However,they suffer from short lifespan and extreme safety concerns,which are attributed to the degradation of layered oxides and the decomposition of electrolyte at high voltage,as well as the high reactivity of metallic Li.The key is the development of stable electrolytes against both highvoltage cathodes and Li with the formation of robust interphase films on the surfaces.Herein,we report a highly fluorinated ether,1,1,1-trifluoro-2-[(2,2,2-trifluoroethoxy)methoxy]ethane(TTME),as a cosolvent,which not only functions as a diluent forming a localized high concentration electrolyte(LHCE),but also participates in the construction of the inner solvation structure.The TTME-based electrolyte is stable itself at high voltage and induces the formation of a unique double-layer solid electrolyte interphase(SEI)film,which is embodied as one layer rich in crystalline structural components for enhanced mechanical strength and another amorphous layer with a higher concentration of organic components for enhanced flexibility.The Li||Cu cells display a noticeably high Coulombic efficiency of 99.28%after 300 cycles and Li symmetric cells maintain stable cycling more than 3200 h at 0.5 mA/cm^(2) and 1.0m Ah/cm^(2).In addition,lithium metal cells using LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) and Li CoO_(2) cathodes(both loadings~3.0 m Ah/cm^(2))realize capacity retentions of>85%over 240 cycles with a charge cut-off voltage of 4.4 V and 90%for 170 cycles with a charge cut-off voltage of 4.5 V,respectively.This study offers a bifunctional ether-based electrolyte solvent beneficial for high-voltage Li metal batteries.

Flow field, sedimentation, and erosion characteristics around folded linear HDPE sheet sand fence: Numerical simulation study

Wind and sand hazards are serious in the Milan Gobi area of the Xinjiang section of the Korla Railway. In order to ensure the safe operation of railroads, there is a need for wind and sand protection in heavily sandy areas. The wind and sand flow in the region is notably bi-directional. To shield railroads from sand, a unique sand fence made of folded linear high-density polyethylene(HDPE) is used, aligning with the principle that the dominant wind direction is perpendicular to the fence. This study employed field observations and numerical simulations to investigate the effectiveness of these HDPE sand fences in altering flow field distribution and offering protection. It also explored how these fences affect the deposition and erosion of sand particles. Findings revealed a significant reduction in wind speed near the fence corner;the minimum horizontal wind speed on the leeward side of the first sand fence(LSF) decreased dramatically from 3 m/s to 0.64 m/s. The vortex area on the LSF markedly impacted horizontal wind speeds. Within the LSF, sand deposition was a primary occurrence. As wind speeds increased, the deposition zone shrank, whereas the positive erosion zone expanded. Close to the folded corners of the HDPE sand fence, there was a notable shift from the positive erosion zone to a deposition zone. Field tests and numerical simulations confirmed the high windproof efficiency(WE) and sand resistance efficiency(SE) in the HDPE sand fence. Folded linear HDPE sheet sand fence can effectively slow down the incoming flow and reduce the sand content, thus achieving good wind and sand protection. This study provides essential theoretical guidance for the design and improvement of wind and sand protection systems in railroad engineering.

Local failure mechanism of sand-blocking fence in latticed dune along desert roads

The latticed dunes in the Tengger Desert are widely distributed,and the sand-blocking fence placed here are highly susceptible to local failure due to complex wind-sand activities,posing a serious threat to the safe operation of the highway.To explore the local failure mechanism of sand-blocking fence in the latticed dune area,the local failure of sand-blocking fence in the latticed dune areas along the Wuhai-Maqin Highway in China was observed.Taking the first main ridge of the latticed dune as the placement location,the structure of the wind-sand flow field of sand-blocking fence placed at top,the bottom and the middle of windward slope was analyzed by Computational Fluid Dynamics(CFD).The results show that when placed at top of the first main ridge,the wind speed near the sand-blocking fence is the highest,up to 15.23 m/s.Therefore,the wind load strength on the sand barrier is correspondingly larger,up to 232.61 N∙m-2.As the strength of material continues to decrease,the nylon net is prone to breakage.The roots of the angle steel posts are susceptible to hollowing by vortex action,which can cause sand-blocking fence to fall over in strong wind conditions.When placed at the bottom of windward slope,wind speed drop near sand-blocking fence is greatest,with the decrease of 12.48-14.32 m/s compared to the original wind speed.This is highly likely to lead to large-scale deposition of sand particles and burial of the sand-blocking fence.When placed in the middle of windward slope,sand-blocking fence is subjected to less wind load strength(168.61N∙m-2)and sand particles are mostly deposited at the bottom of windward slope,with only a small amount of sand accumulating at the root of sand-blocking fence.Based on field observations and numerical modelling results,when the sand-blocking fence is placed in latticed dune area,it should be placed in the middle of the windward slope of the first main ridge as a matter of priority.Besides the sand-blocking fence should be placed at the top of the first main ridge,and sand fixing measures should be added.

Electric field and force characteristic of dust aerosol particles on the surface of high-voltage transmission line

High-voltage transmission lines play a crucial role in facilitating the utilization of renewable energy in regions prone to desertification. The accumulation of atmospheric particles on the surface of these lines can significantly impact corona discharge and wind-induced conductor displacement. Accurately quantifying the force exerted by particles adhering to conductor surfaces is essential for evaluating fouling conditions and making informed decisions. Therefore, this study investigates the changes in electric field intensity along branched conductors caused by various fouling layers and their resulting influence on the adhesion of dust particles. The findings indicate that as individual particle size increases, the field strength at the top of the particle gradually decreases and eventually stabilizes at approximately 49.22 k V/cm, which corresponds to a field strength approximately 1.96 times higher than that of an unpolluted transmission line. Furthermore,when particle spacing exceeds 15 times the particle size, the field strength around the transmission line gradually decreases and approaches the level observed on non-adhering surface. The electric field remains relatively stable. In a triangular arrangement of three particles, the maximum field strength at the tip of the fouling layer is approximately 1.44 times higher than that of double particles and 1.5 times higher compared to single particles. These results suggest that particles adhering to the transmission line have a greater affinity for adsorbing charged particles. Additionally, relevant numerical calculations demonstrate that in dry environments, the primary adhesion forces between particles and transmission lines follow an order of electrostatic force and van der Waals force. Specifically, at the minimum field strength, these forces are approximately74.73 times and 19.43 times stronger than the gravitational force acting on the particles.

Protective benefits of HDPE board sand fences in an environment with variable wind directions on Gobi surfaces:wind tunnel study

The Golmud-Korla Railway in the Gobi area faces operational challenges due to sand hazards,caused by strong and variable winds.This study addresses these challenges by conducting wind tunnel tests to evaluate the protective benefits of High Density Polyethylene(HDPE)board sand fences,focusing on their orientation relative to various wind directions(referred to as'wind angle').This study found that the size of the low-velocity zone on the leeward side of the sand fences(LSF)expanded with an increase in the wind angle(WA).At 1H(the height of the sand fence)and 2H positions on the LSF,the wind speed profiles(WSP)exhibited a segmented logarithmic growth,constrained by Z=H at varying WAs.The efficacy of the sand fence in obstructing airflow escalated as WA increased.The size of the WA has a significant impact on the protective efficiency of HDPE board sand fences.Furthermore,compared to typical sandy surfaces,the rate of sand transport across the Gobi surface diminishes more slowly with height,attributed to the gravel's rebound effect.This phenomenon allows some sand particles to bypass the fences,rendering them less effective at blocking wind and trapping sand than in sandy environments.This paper offers scientific evidence supporting the practical use and enhancement of HDPE board sand fences in varied wind conditions.

Degradation analysis and doping modification optimization for high-voltage P-type layered cathode in sodium-ion batteries

Advancing high-voltage stability of layered sodium-ion oxides represents a pivotal avenue for their progress in energy storage applications.Despite this,a comprehensive understanding of the mechanisms underpinning their structural deterioration at elevated voltages remains insufficiently explored.In this study,we unveil a layer delamination phenomenon of Na_(0.67)Ni_(0.3)Mn_(0.7)O_(2)(NNM)within the 2.0-4.3 V voltage,attributed to considerable volumetric fluctuations along the c-axis and lattice oxygen reactions induced by the simultaneous Ni^(3+)/Ni^(4+)and anion redox reactions.By introducing Mg doping to diminished Ni-O antibonding,the anion oxidation-reduction reactions are effectively mitigated,and the structural integrity of the P2 phase remains firmly intact,safeguarding active sites and precluding the formation of novel interfaces.The Na_(0.67)Mg_(0.05)Ni_(0.25)Mn_(0.7)O_(2)(NMNM-5)exhibits a specific capacity of100.7 mA h g^(-1),signifying an 83%improvement compared to the NNM material within the voltage of2.0-4.3 V.This investigation underscores the intricate interplay between high-voltage stability and structural degradation mechanisms in layered sodium-ion oxides.

How do high-voltage cathode and PEO electrolyte get along well?EIS analysis mechanism&potentiometric control strategy

PEO-based all-solid-state electrolytes are extensively utilized and researched owing to their exceptional safety,low-mass-density,and cost-effectiveness.However,the low oxidation potential of PEO makes the interface problem with the high-voltage cathode extremely severe.In this work,the impedance of PEO-based all-solid-state batteries with high-voltage cathode(NCM811)was studied at different potentials.The Nyquist plots displayed a gyrate arc at low-frequencies for NCM811/PEO interface.Based on the kinetic modeling,it was deduced that there is a decomposition reaction of PEO-matrix in addition to de-embedded reaction of NCM811,and the PEO intermediate product(dehydra-PEO)adsorbed on the electrode surface leading to low-frequency inductive arcs.Furthermore,the distribution of relaxation time shows the dehydra-PEO results in the kinetic tardiness of the charge transfer process in the temporal dimension.Hence,an artificial interface layer(CEI_(x))was modified on the surface of NCM811 to regulate the potential of cathode/electrolyte interface to prevent the high-voltage deterioration of PEO.NCM/CEI_(x)/PEO batteries exhibit capacity retentions of 96.0%,84.6%,and 76.8%after undergoing 100 cycles at cut-off voltages of 4.1,4.2,and 4.3 V,respectively.Therefore,here the failure mechanism of high-voltage PEO electrolyte is investigated by EIS and a proposed solving strategy is presented.

Benefits and ecological restoration implications of hanging grass fences in Mongolian desert steppe

Tumbleweeds participate in a common seasonal biological process in temperate grasslands,creating hanging grass fences during the grass-withering season that result in distinct ecological phenomena.In this study,we addressed the urgent need to understand and restore the degraded desert steppe in Central Mongolia,particularly considering the observed vegetation edge effects around hanging grass fences.Using field surveys conducted in 2019 and 2021 in the severely degraded desert steppe of Central Mongolia,we assessed vegetation parameters and soil physical and chemical properties influenced by hanging grass fences and identified the key environmental factors affecting vegetation changes.The results indicate that the edge effects of hanging grass fences led to changes in species distributions,resulting in significant differences in species composition between the desert steppe's interior and edge areas.Vegetation parameters and soil physical and chemical properties exhibited nonlinear responses to the edge effects of hanging grass fences,with changes in vegetation coverage,aboveground biomass,and soil sand content peaking at 26.5,16.5,and 6.5 m on the leeward side of hanging grass fences,respectively.In the absence of sand dune formation,the accumulation of soil organic carbon and available potassium were identified as crucial factors driving species composition and increasing vegetation coverage.Changes in species composition and plant density were primarily influenced by soil sand content,electrical conductivity,and sand accumulation thickness.These findings suggest that hanging grass fences have the potential to alter vegetation habitats,promote vegetation growth,and control soil erosion in the degraded desert steppe of Central Mongolia.Therefore,in the degraded desert steppe,the restoration potential of hanging grass fences during the enclosure process should be fully considered.

Understanding the failure mechanism towards developing high-voltage single-crystal Ni-rich Co-free cathodes

Benefited from its high process feasibility and controllable costs,binary-metal layered structured LiNi_(0.8)Mn_(0.2)O_(2)(NM)can effectively alleviate the cobalt supply crisis under the surge of global electric vehicles(EVs)sales,which is considered as the most promising nextgeneration cathode material for lithium-ion batteries(LIBs).However,the lack of deep understanding on the failure mechanism of NM has seriously hindered its application,especially under the harsh condition of high-voltage without sacrifices of reversible capacity.Herein,singlecrystal LiNi_(0.8)Mn_(0.2)O_(2) is selected and compared with traditional LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM),mainly focusing on the failure mechanism of Cofree cathode and illuminating the significant effect of Co element on the Li/Ni antisite defect and dynamic characteristic.Specifically,the presence of high Li/Ni antisite defect in NM cathode easily results in the extremely dramatic H2/H3 phase transition,which exacerbates the distortion of the lattice,mechanical strain changes and exhibits poor electrochemical performance,especially under the high cutoff voltage.Furthermore,the reaction kinetic of NM is impaired due to the absence of Co element,especially at the single-crystal architecture.Whereas,the negative influence of Li/Ni antisite defect is controllable at low current densities,owing to the attenuated polarization.Notably,Co-free NM can exhibit better safety performance than that of NCM cathode.These findings are beneficial for understanding the fundamental reaction mechanism of single-crystal Ni-rich Co-free cathode materials,providing new insights and great encouragements to design and develop the next generation of LIBs with low-cost and high-safety performances.

High-Voltage and Fast-Charging Lithium Cobalt Oxide Cathodes: From Key Challenges and Strategies to Future Perspectives

Lithium-ion batteries(LIBs)with the“double-high”characteristics of high energy density and high power density are in urgent demand for facilitating the development of advanced portable electronics.However,the lithium ion(Li+)-storage performance of the most commercialized lithium cobalt oxide(LiCoO_(2),LCO)cathodes is still far from satisfactory in terms of high-voltage and fast-charging capabilities for reaching the double-high target.Herein,we systematically summarize and discuss high-voltage and fast-charging LCO cathodes,covering in depth the key fundamental challenges,latest advancements in modification strategies,and future perspectives in this field.Comprehensive and elaborated discussions are first presented on key fundamental challenges related to structural degradation,interfacial instability,the inhomogeneity reactions,and sluggish interfacial kinetics.We provide an instructive summary of deep insights into promising modification strategies and underlying mechanisms,categorized into element doping(Li-site,cobalt-/oxygen-site,and multi-site doping)for improved Li+diffusivity and bulkstructure stability;surface coating(dielectrics,ionic/electronic conductors,and their combination)for surface stability and conductivity;nanosizing;combinations of these strategies;and other strategies(i.e.,optimization of the electrolyte,binder,tortuosity of electrodes,charging protocols,and prelithiation methods).Finally,forward-looking perspectives and promising directions are sketched out and insightfully elucidated,providing constructive suggestions and instructions for designing and realizing high-voltage and fast-charging LCO cathodes for next-generation double-high LIBs.

Protective benefit of folded linear HDPE board sand fences along the Golmud-Korla Railway,China:Field observation and wind tunnel study

The Milan Gobi area of the Golmud-Korla Railway in northwest China is located in the lower dispersal area of the mountain pass and has strong winds with evident double wind direction characteristics.This study introduced a novel sand fence deployment technique,termed‘folded linear deployment',designed to position the sand fence orthogonally to the two predominant wind directions for optimal protection.This study used wind tunnel and field tests to evaluate the wind and sand flow characteristics,as well as the windproof and sandresistant performance of folded linear HDPE(Highdensity polyethylene)board sand fences.The results suggest that the airflow around the fence creates clear zoning characteristics.The deceleration area on the BSF(backwind side of the sand fence)is much larger than that on the DSF(downwind side of the sand fence).Thus,sand particles are primarily deposited on the BSF.At different wind speeds,the airflow at 2 and 5 h on the DSF is not disturbed.The WSP(wind speed profile)presents a logarithmic distribution.The airflow is disturbed at 1-20 h on the BSF,and the WSP gradually deviates from the logarithmic law.However,as the airflow moves away from the fence,the WSP gradually approaches a logarithmic distribution.Meanwhile,the WPE(windproof efficiency)and SRE(sand-resistant efficiency)of the sand fence exceed 80%.In addition,the results of wind tunnel tests are compared with those of field tests.The overall dispersion is good,and the best dispersion is found at z/H=2.00,indicating good agreement between the two test results.This study provides a scientific basis for the design of sand hazard control measures,similar to the railway project in the Gobi Gale area.

–C≡N functionalizing polycarbonate-based solid-state polymer electrolyte compatible to high-voltage cathodes

Solid-state polymer electrolytes(SPEs) capable of withstanding high voltage are considered to be key for next-generation energy storage devices with inherent safety as well as high energy density.This study involves the rational design of solid-state-C≡N functionalized P(VEC_1-CEA_(0.3))/LiTFSI@CE SPEs and its synthesis by in-situ free radical polymerization of vinyl ethylene carbonate(VEC) and 2-cyanoethyl acrylate(CEA).In situ polymerization yields electrode/electrolyte interfaces with low interfacial resistance,forming a stable SEI layer enriched with LiF,Li_(3)N,and RCOOLi,ensuring stable Li plating/stripping for over 1400 h.The-C≡N moiety renders the αH on the adjacent αC positively charged,thereby endowing it with the capability to anchor TFSI^(-).Simultaneously,the incorporation of-C≡N moiety diminishes the electron-donating ability of the C=O,C-O-C,and-C≡N functional groups,facilitating not only the ion conductivity enhancement but also a more rapid Li^(+)migration proved by DFT theoretical calculations and Raman spectroscopy.At room temperature,t_(Li+) of 0.60 for P(VEC_1-CEA_(0.3))/LiTFSI@CE SPEs is achieved when the ionic conductivity σ_(Li+)is 2.63×10^(-4) S cm^(-1) and the electrochemical window is expanded to5.0 V.Both coin cells with high-areal-loading cathodes and the 6.5-mAh pouch cell,exhibit stable charge/discharge cycling.At 25℃,the 4.45-V Li|P(VEC_1-CEA_(0.3))/LiTFSI@CE|LiCoO_(2) battery performs stable cycling over 200 cycles at 0.2 C,with a capacity retention of 82.1%.

Pairing nitroxyl radical and phenazine with electron-withdrawing/-donating substituents in “water-in-ionic liquid” for high-voltage aqueous redox flow batteries

Aqueous redox-active organic materials-base electrolytes are sustainable alternatives to vanadium-based electrolyte for redoxflow batteries(RFBs)due to the advantages of high ionic conductivity,environmentally benign,safety and low cost.However,the underexplored redox properties of organic materials and the narrow thermodynamic electrolysis window of water(1.23 V)hinder their wide applications.Therefore,seeking suitable organic redox couples and aqueous electrolytes with a high output voltage is highly suggested for advancing the aqueous organic RFBs.In this work,the functionalized phenazine and nitroxyl radical with electron-donating and electron-withdrawing group exhibit redox potential of-0.88 V and 0.78 V vs.Ag,respectively,in“water-in-ionic liquid”supporting electrolytes.Raman spectra reveal that the activity of water is largely suppressed in“water-in-ionic liquid”due to the enhanced hydrogen bond interactions between ionic liquid and water,enabling an electrochemical stability window above 3 V.“Water-in-ionic liquid”supporting electrolytes help to shift redox potential of nitroxyl radical and enable the redox activity of functionalized phenazine.The assembled aqueous RFB allows a theoretical cell voltage of 1.66 V and shows a practical discharge voltage of 1.5 V in the“water-in-ionic liquid”electrolytes.Meanwhile,capacity retention of 99.91%per cycle is achieved over 500 charge/discharge cycles.A power density of 112 mW cm^(-2) is obtained at a current density of 30 mA cm^(-2).This work highlights the importance of rationally combining supporting electrolytes and organic molecules to achieve high-voltage aqueous RFBs.

Performance Characterization of Visible Light Communication Based on GaN High-Voltage LED/PD

While considerable research has been conducted on the structural principles,fabrication techniques,and photoelectric properties of high-voltage light-emitting diodes(LEDs),their performance in light communication remains underexplored.A high-voltage seriesconnected LED or photodetector(HVS-LED/PD)based on the gallium nitride(GaN)integrated photoelectronic chip is presented in this paper.Multi-quantum wells(MQW)diodes with identical structures are integrated onto a single chip through wafer-scale micro-fabrication techniques and connected in series to construct the HVS-LED/PD.The advantages of the HVS-LED/PD in communication are explored by testing its performance as both a light transmitter and a PD.The series connection enhances the device's 3 dB bandwidth,allowing it to increase from 1.56 MHz to a minimum of 2.16 MHz when functioning as an LED,and from 47.42 kHz to at least 85.83 kHz when operating as a PD.The results demonstrate that the light communication performance of HVS-LED/PD is better than that of a single GaN MQW diode with bandwidth and transmission quantity,which enriches the research of GaN-based high-voltage devices.

Study of the Effect of High-Voltage Low-Frequency Electrotherapy on Type 2 Diabetes in an in Vivo Model

The study investigates the impact of high-voltage low-frequency electrotherapy on glucose levels and hematological parameters in an in vivo model of type 2 diabetes. The results demonstrate a significant reduction in glucose increases during glucose tolerance tests (GTT) and suggest potential mechanisms, including improved insulin sensitivity and reduced inflammation. Hematological analysis indicates no adverse effects of electrotherapy on healthy or diabetic mice. This study supports the potential of high-voltage low-frequency electrotherapy as an adjunctive treatment for type 2 diabetes, warranting further research into its mechanisms and long-term effects.

Nonlinear dynamical response of high-voltage transmission lines based on cable dropping

In order to study the dynamic response of high-voltage transmission lines under mechanical failure, a finite element model of a domestic 500-kV high-voltage transmission line system is established. The initial equilibrium condition of the coupling system model is verified by nonlinear static analysis. The transient dynamic analysis method is proposed to analyze the variation law of dynamic response under cable or insulator rupture, and the dynamic response of structural elements next to the broken span is calculated. The results show that upper crossarm cable rupture has no effect on cable tension at adjacent suspension points, but it has a significant influence on tension in the insulator and the tower component of the upper crossarm next to the broken span. The peak tension in the conductor of the upper crossarm at the suspension point exceeds the design value under insulator rupture. Insulator rupture has no effect on the tower component of the upper crossarm, but it has a significant influence on insulator tension of the upper crossarm. Insulator rupture should be taken into account in the design of overhead transmission lines. The research results can provide a theoretical basis for the design of transmission lines.

High-Voltage MOSFETs in a 0.5μm CMOS Process

There is growing interest in developing high-voltage MOSFET devices that can be integrated with low-voltage CMOS digital and analog circuits. In this paper,high-voltage nand p-type MOSFETs are fabricated in a commercial 3.3/ 5V 0.5μm n-well CMOS process without adding any process steps using n-well and p-channel stops. High current and highvoltage transistors with breakdown voltages between 23 and 35V for the nMOS transistors with different laydut parameters and 19V for the pMOS transistors are achieved. This paper also presents the insulation technology and characterization results for these high-voltage devices.

第251首Over the Fence-中的戏剧独白特征

狄金森第251首Over the Fence-具有戏剧独白的一些典型特征,如叙述者为充满童趣的小女孩,体现戏剧情境的词语包括"fence"、"strawberries"和"nice",揭示戏剧冲突的词汇或从句包括"over the fence"、"but"和"if"条件句。对这些特征的阐释可提供多元解读狄金森诗歌作品的空间,从而既有助于管窥当时社会的总体风貌和两性不平等问题,还能更加丰富对狄金森诗歌作品思想深度和艺术特色的相关研究。

Impact of pond and fence aquaculture on reservoir environment

With the rapid development of aquaculture in lakes and reservoirs, its negative effects on water quality and aquatic organisms are clearly emerging. Toward a better understanding of these effects, chemical and biological monitoring was conducted in the Fangbian Reservoir to study the relationship between aquaculture and eutrophication. As a domestic water supply source, this reservoir has reached the mesotrophic level. The concentrations of total nitrogen （TN） and total phosphorus （TP） in the Fangbian Reservoir have frequently exceeded the prescriptive level according to the Environmental Quality Standardgfor SurJace Water （GB3838-2002）. Pond and fence aquaculture feeding is the main cause of high levels of nitrogen and phosphorus, accounting for nearly half of the total pollution, and causing the reservoir environmental capacity to be exceeded. The amounts of nitrogen and phosphorus that went directly to the reservoir through the residual bait and fish droppings in fence aquaculture were 42 768 kg per year and 10 856 kg per year respectively, from 2007 to 2009. About 2 913 kg of nitrogen and 450 kg of phosphorus were imported to the reservoir through the exchange of water from the culturing ponds at the same time. Therefore, controlling the aquaculture scale and promoting eco-aquaculture are key measures for lessening the eutrophication degree and improving the water quality.

Mechanism and effects of snow accumulations and controls by lightweight snow fences

This paper investigates the snowdrifts caused by lightweight fences along the lines on the flatland through the computational fluid dynamics method. The characteristic ambient flows around the solid fences and the porous fences with varied heights and bottom wind gaps are simulated in the numerical model, and the working mechanism of ＂interception＂ and ＂scouring＂ of the lightweight fences are analyzed. Based on the friction velocities near the ground, two sets of criteria are proposed to evaluate the deposition and erosion effects of different fences. According to flow separation and reattachment, the simplified relationships between the most likely positions for snow accumulations and fence parameters are devel- oped. The study indicates that the capabilities for snow interception by the solid fence without wind gap and the distance from which to the second snow coverage center both increase with the fence height. Furthermore, it is found that the scouring range for snow surface increases significantly with the size of wind gap, and the snow accumulation rate on the leeward side decreases with the increasing fence porosity.