The blocking effect of the sand fences quantified using wind tunnel simulations

Fences are one of the most effective measures to prevent and control wind-blown sand disasters,and the blocking effect of fences is largely determined by their porosity and height(H).This study employed wind tunnel experiments to measure wind velocities on both sides of wire mesh sand fences with porosities of 75%,63%,56%,36%and heights of 10,5 and 2 cm.The effects of porosity and height on the blocking effect of the fences were evaluated on the basis of velocity variability,flow field,and the wind velocity reduction coefficient.Results show that the smaller the porosity,the stronger the blocking effect.The fence with a porosity of 36%had the strongest windproof efficiency of 0.70 and longest protection range of 9 H,and thus showed the best applicability in preventing and controlling wind-blown sand disasters.The fence with a porosity of 56%showed a windproof efficiency of 0.31 and a protection range of 7 H,which could be considered for adoption.However,fences with porosities of 75%and 63%were not recommended to be adopted,because their windproof efficiency and protection range were very small.Overall,the higher the fence,the stronger the blocking effect.The highest fence(10 cm)had the longest protection range of 90 cm,which was the best in application.Nevertheless,the 5 and 2 cm fences were almost consistent with 10 cm fence in windproof efficiency,which was still suitable for wind and sand fixation.

Water blocking effect caused by the use of hydraulic methods for permeability enhancement in coal seams and methods for its removal

To research techniques for removing the water blocking effect caused by hydraulic applications in coal seams,the use of surfactants is proposed,based on the mechanics of the water blocking effect.Centrifugal experiments were used to validate the effects of using surfactants;the results show that after dealing with vacuum saturation with water,the volume of micropores decreases,which results in a larger average pore size,and the volume of transitional pores,mesopores,macropores and total pores increases.Based on the distribution of pore size,the operation mode of ‘‘water infusion after gas extraction,then continuing gas extraction" is recommended to improve the volume of coal mine gas drainage.When the reflectance of vitrinite in coal samples is less than 1,using the surfactants Fast T,1631,APG,BS can mitigate the damage caused by the water blocking effect.But when the reflectance of vitrinite is larger than 1.4,the damage caused by the water blocking effect can be increased.When the surfactant CMC is used in hydraulic applications,the capillary forces of coal samples are almost negative,which means the capillary force is in the same direction as the gas extraction.The direction of capillary forces benefits the gas flow.So,using CMC can play an active role in removing the water blocking effect.Centrifugal experiments confirm that using CMC can effectively remove the water blocking effect,which has a beneficial effect on improving the gas drainage volume.

Effect of specifically-adsorbed polysulfides on the electron transfer kinetics of sodium metal anodes

Room-temperature sodium-sulfur(RT Na-S)batteries hold great promise for large-scale energy storage applications owing to the high energy density and earth-abundance of Na and S.However,the dissolution and migration of sodium polysulfides,uncontrollable Na dendrite growth,and the lack of studies on Na electrodeposition kinetics have hindered the development of these batteries.Herein,we reveal the mechanism of sodium polysulfides on the Na plating/stripping kinetics using a three-electrode system.First,the kinetic behavior deviates from the commonly supposed Butler-Volmer model,which is well described by the Marcus model.In addition,the specific adsorption of polysulfides on the sodium electrode surface is a key factor influencing the kinetics.Higher-order polysulfides(S_(8)^(2-)and S_(6)^(2-))exhibit distinct specific adsorption behaviors because of their high adsorption energies compared to lower-order polysulfides(S_(4)^(2-)and S_(2)^(2-)).The electrostatic effect caused by specific adsorption can accelerate the kinetics,whereas the blocking effect can slow the kinetics.Thus,this competitive relationship enables low concentrations of high-order polysulfides to stimulate kinetics.This implies that a weak shuttle effect is beneficial for obtaining a stable Na deposition in RT Na-S batteries.An in-depth understanding of the Na electrodeposition kinetics provides beneficial clues for future metal sodium/electrolyte interface designs.

Blocking Effects of Spleen Vaccine on Vertical Transmission of Classical Swine Fever Virus in Sows

[ Objective] To investigate the blocking effects of spleen vaccine on vertical transmission of classical swine fever virus （CSFV） in sows. [ Method] Sows infected by CSFV were selected from three large-scale pig farms and they were randomly divided into group Ⅰ, group Ⅱ and control group. The sows in the group Ⅰ were vaccinated with CSF spleen vaccine at a 1.5 times normal dose per pig; those in the group Ⅱ were vaccinated with CSF spleen vaccine at a 2.0 times normal dose per pig; and those in the control group were vaccinated with cell vaccine at a 4.0 times normal- dose per pig. The CSF antigens of piglets were detected by enzyme-linked immunosorbent assay （ELISA）. [ Result] The antigen positive rate of piglets in the experimental group （18.5%） was significantly lower than that in the control group （48.1% ）. No significant difference was found be- tween the group Ⅰ and the group Ⅱ. [ Condmion] CSF spleen vaccine has good blocking effects on vertical transmission of CSFV in sows.

The Blocking Effect of Phenolic Acid on N-Nitrosomorpholine Formation in vitro

Phenolic acids (PAs) are widely found in many daily consumed vegetables and fruits.The inhibitory effects of PAs on Nnitrosomorpholine (NMOR) formation in vitro undersimulated gastric juice condition were studied. The results showed that the inhibjtoryIX)tency of thirteen varieties of PAs differed greatly, which may be related to theirchemical structures; the blocking rate (BR) of different killds of PAs were as follows:caf feic acid, 92.5%; tannic acid, 90.0%; gallic acid, 86.8%; sinaPinic acid, 86.2%; ferulicacid, 8l.l%; chlorogenic acid, 69.4%; gentisic acid, 69.2%; syringic acid, 62.1%; protocatechuic acid, 56.0%; p-coumaric acid, 52.5%; vannilic acid, 35.4%; moreover,p-hydroxybenzoic acid and m-coumaric acid had the least blocking effect or even slightcatalyzing effect. The results also demonstrated that amounts of NMOR formed werenegatively correlated with molar ratio of PAs to nitrite and that the optimum pH forinhibition was between 2 and 3.

Effect of cerebral lymphatic block on cerebral morphology and cortical evoked potential in rats

BACKGROUND: It has been shown that although brain does not contain lining endothelial lymphatic vessel, it has lymphatic drain. Anterior lymphatic system of lymphatic vessel in brain tissue plays a key role in introducing brain interstitial fluid to lymphatic system; however, the significance of lymphatic drain and the effect on cerebral edema remains unclear. OBJECTIVE: To investigate the effect of cerebral lymphatic block on cerebral morphology and cortical evoked potential in rats. DESIGN: Randomized controlled animal study. SETTING: Institute of Cerebral Microcirculation of Taishan Medical College and Department of Neurology of Affiliated Hospital. MATERIALS: A total of 63 healthy adult male Wistar rats weighing 300-350 g were selected in this study. Forty-seven rats were used for the morphological observation induced by lymphatic drain and randomly divided into three groups: general observation group (n =12), light microscopic observation group (n =21) and electronic microscopic observation group (n =14). The rats in each group were divided into cerebral lymphatic block subgroup and sham-operation control subgroup. Sixteen rats were used for observing the effect of cerebral lymphatic block on cortical evoked potential, in which the animals were randomly divided into sham-operation group (n =6) and cerebral lymphatic block group (n =10). METHODS: The experiment was carried out in the Institute of Cerebral Microcirculation of Taishan Medical College from January to August 2003. Rats in cerebral lymphatic block group were anesthetized and separated bilateral superficial and deep cervical lymph nodes under sterile condition. Superior and inferior boarders of lymph nodes were ligated the inputting and outputting channels, respectively, and then lymph node was removed so as to establish cerebral lymphatic drain disorder models. Rats in sham-operation control group were not ligated the lymphatic vessel and removed lymph nodes, and other operations were as the same as those in cerebral lymphatic block group. Morphological changes of the brain and alterations of latency of cortical evoked potential were detected on the 1st, 2nd, 3rd, 5th, 7th, 10th and 15th days after operation under general, light microscope and electronic microscope observations. MAIN OUTCOME MEASURES: ① Cerebral morphological changes; ② latent changes of cortical evoked potential. RESULTS: A total of 63 rats were involved in the final analysis. ① Cerebral morphological changes: General observation showed that, for cerebral lymphatic block rats, the surface of brain was pale and full, and cerebral gyrus was wide and flattened sulci after cerebral lymphatic block; and cerebral tissue space prolongation, increased interstitial fluid, neuronal degeneration and necrosis, diffused phagocytes and satellitosis were observed under light microscope. Neuronal swell and necrosis, glial cell swell, apparent subcellular changes such as mitochondron were observed under electronic microscope. ② Latent changes of cortical evoked potential: As compared with sham-operation control group, latency of cortical evoked potential in cerebral lymphatic blockage group prolonged on the 5th day and 7th day after cerebral lymphatic block [(6.28±0.23), (6.97±0.35) ms; (6.23±0.22), (7.12±0.20) ms; P < 0.01]. CONCLUSION: ① Cerebral lymphatic block plays an important role in cerebral morphology, and may result in abnormality of sensitive impulse conduction and prolong latency of cortical evoked potential. ② Examination of cortical evoked potential is easy and convenient, so it is regarded as a key index for lymphatic disturbed cerebral injury.

Effect of Mg-Preflow for p-AlGaN Electron Blocking Layer on the Electroluminescence of Green LEDs with V-Shaped Pits

In GaN-based green light-emitting diodes（LEDs） with and without Mg-preflow before the growth of p-Al GaN electron blocking layer（EBL） are investigated experimentally.A higher Mg doping concentration is achieved in the EBL after Mg-preflow treatment,effectively alleviating the commonly observed efficiency collapse and electrons overflowing at cryogenic temperatures.However,unexpected decline in quantum efficiency is observed after Mg-preflow treatment at room temperature.Our conclusions are drawn such that the efficiency decline is probably the result of different emission positions.Higher Mg doping concentration in the EBL after Mg-preflow treatment will make it easier for a hole to be injected into multiple quantum wells with emission closer to pGaN side through the（8-plane rather than the V-shape pits,which is not favorable to luminous efficiency due to the preferred occurrence of accumulated strain relaxation and structural defects in upper QWs closer to p-GaN.Within this framework,apparently disparate experimental observations regarding electroluminescence properties,in this work,are well reconciled.

Impact of anisotropic growth on kinetics of solid-state phase transformation

Based on the statistical analysis of blocking effect arising from anisotropic growth,the anisotropic effect on the kinetics of solid-state transformation was investigated.The result shows that the blocking effect leads to the retardation of transformation and then a regular behavior of varying Avrami exponent.Following previous analytical model,the formulations of Avrami exponent and effective activation energy accounting for blocking effect were obtained.The anisotropic effect on the transformation depends on two factors,non-blocking factor γ and blocking scale k,which directly acts on the dimensionality of growth.The effective activation energy is not affected by the anisotropic effect.The evolution of anisotropic effect with the fraction transformed is taken into account,showing that the anisotropic effect is more severe at the middle stage of transformation.

Tianwen-1 MINPA observations in the solar wind

The Mars Ion and Neutral Particle Analyzer(MINPA)is one of the three scientific instruments onboard the Tianwen-1 orbiter to investigate the Martian space environment.During Tianwen-1’s transfer orbit to Mars,the MINPA was switched on to measure the solar wind ions.Here,we present the first results of the MINPA observations in the solar wind.During cruise,nearly half of the MINPA ion field-of-view(FOV)was blocked by the lander capsule;thus only the solar-wind ions with azimuthal speeds pointing towards the unblocked FOV sectors could be detected.We perform a detailed comparison of the MINPA’s solar wind observations with data from Earth-based missions when MINPA reached its count-rate peak,finding a general consistency of the ion moments between them.The blocking effect due to the lander is evaluated quantitatively under varying solar-wind velocity conditions.Despite the blocking effect,the MINPA’s solar wind measurements during the transfer orbit suggest a good performance.

Propagating adaptive-weighted vector median filter for motion-field smoothing

In the field of predictive video coding and format conversion, there is an increasing attention towards estimation of the true inter-frame motion. The restoration of motion vector field computed by 3-D RS is addressed and a propagating adaptive-weighted vector median (PAWVM) post-filter is proposed. This approach decomposes blocks to make a better estimation on object borders and propagates good vectors in the scanning direction. Furthermore, a hard-thresholding method is introduced into calculating vector weights to improve the propagating. By exploiting both the spatial correlation of the vector field and the matching error of candidate vectors, PAWVM makes a good balance between the smoothness of vector field and the prediction error, and the output vector field is more valid to reflect the true motion.

Spin and valley half metal induced by staggered potential and magnetization in silicene

We investigate the electron transport in silicene with both staggered electric potential and magnetization; the latter comes from the magnetic proximity effect by depositing silicene on a magnetic insulator. It is shown that the silicene could be a spin and valley half metal under appropriate parameters when the spin–orbit interaction is considered; further, the filtered spin and valley could be controlled by modulating the staggered potential or magnetization. It is also found that in the spin-valve structure of silicene, not only can the antiparallel magnetization configuration significantly reduce the valve-structure conductance, but the reversing staggered electric potential can cause a high-performance magnetoresistance due to the spin and valley blocking effects. Our findings show that the silicene might be an ideal basis for the spin and valley filter analyzer devices.

Mechanisms of shale hydration and water block removal

Shale samples of Silurian Longmaxi Formation in the Changning area of the Sichuan Basin, SW China, were selected to carry out scanning electron microscopy, CT imaging, high-pressure mercury injection, low-temperature nitrogen adsorption and imbibition experiments to compare the hydration characteristics of montmorillonite and illite, analyze the main factors affecting the water block removal of shale, and reveal the mechanisms of pore structure evolution during shale hydration. The hydration characteristics of shale are closely related to the composition of clay minerals, the shale with high illite content is not susceptible to hydration and thus has limited room for pore structure improvement;the shale with high montmorillonite is susceptible to hydration expansion and thus has higher potential of pore structure improvement by stimulation;the shale with high illite content has stronger imbibition in the initial stage, but insufficient diffusion ability, and thus is likely to have water block;the shale with high montmorillonite content has weaker imbibition in the initial stage but better water diffusion, so water blocking in this kind of shale can be removed to some degree;the shale reservoir has an optimal hydration time, when it is best in physical properties, but hydration time too long would cause damage to the reservoir, and the shale with high illite content has a shorter optimal hydration time;inorganic cations can inhibit the hydration of clay minerals and have stronger inhibition to illite expansion, especially K^(+);for the reservoir with high content of montmorillonite, the cation content of fracturing fluid can be lowered to promote the shale hydration;fracturing fluid with high K^(+) content can be injected into reservoirs with high illite content to suppress hydration.

循环水通道阻塞效应对自主水下航行器水动力系数估算的影响

The Reynolds-averaged Navier–Stokes(RANS)equation was solved using computational fluid dynamics to study the effect of the circulating tank wall on the hydrodynamic coefficient of an autonomous underwater vehicle(AUV).Numerical results were compared with the experimental results in the circulating water tank of Harbin Engineering University.The numerical results of the model with different scale ratios under the same water in the flume were studied to investigate the effect of blockage on the hydrodynamic performance of AUV in the circulating flume model test.The results show that the hydrodynamic coefficient is stable with the scale reduction of the model.The influence of blocking effect on AUV is given by combining theoretical calculation with experiment.

Functionality of Covalent Organic Framework (COF) in Gas Storage Application: First Principal Study

Industrial growth in recent years led to air pollution and an increase in concentration of hazardous gases such as O3 and NO. Developing new materials is important to detect and reduce air pollutants. While catalytic decomposition and zeolites are traditional ways used to reduce the amount of these gases. We need to develop and explore new promising materials. Covalent organic framework (COF) has become an attractive platform for researcher due to its extended robust covalent bonds, porosity, and crystallinity. In this study, first principal calculations were performed for gases adsorption using COFs containing nitrogen and π-bonds. Different building blocks (BBs) and linkers (LINKs/LINK1 & LINK2) were investigated by means of density functional theory (DFT) calculations with B3LYP and 3-21G basis sets to calculate the binding energies of gases @COF systems. Electrostatic potential maps (ESPM), Mulliken charges and non-covalent interaction (NCI) are used to understand the type of interactions between gas and COFs fragments. O3 was found to bind strongly with COF system in comparison with NO which could make COF a useful selective material for mixed gases environment for sensing and removal application.

BLOCKING EFFECT OF HIGH PRESSURE SYSTEM ON THE FORMATION OF EXTRA-INTENSE HEAVY RAIN

Commonly the centre of an intense heavy rain occurs in a very limited area,but for the three extra- intense heavy rains of the present study,63-8 in North China,75-8 in central China and 77-8 in the desert region of Inner Mongolia,which all appeared under the environments of“Western Low and Eastern Blocking” (EB)pattern.From this study,the following effects of the EB are found:(1)It affects the precipitation systems staggering in a local place and/or changes the trajectories of low votices and urges them into the same raining areas intermittently.(2)It transports water vapour into raining areas.The air flows by the west side of EB produce strong cyclonic vorticity behind EB frequently,which transports water vapour and forms mesoscale precipitation systems more favourably than the low level jets.(3)Air flows behind EB con- jugate with adequate topographic relief,which enhances the precipitation and makes the raining areas over- lapped.So that extra-intense heavy rains could occur in higher latitudes of semi-aird areas,and occasionally even in the desert region of North China. Such extra-intense heavy rains could not be explained by static local humidity and temperature only. This is also a principal discrimination between the prolonged extra-intense heavy rain and the short-range convective precipitation and/or the common precipitation.

Effect of Traditional Chinese Medicine Treatment on Levels of Blocking Antibody, β-hCG, Progesterone and Estradiol in Spontaneous Abortion

Objective: To explore the effect of traditional Chinese medicine (TCM) on abnormalmaternal-fetal immune and endocrine in 24cases of threatened abortion (TA) and 68 cases of recurrent spontaneous abortion (RSA).Methods: The levels of blocking effect (BE),antiidiotype antibody (AIA), cytotoxin antibody (CTA), β-human chorionic gonadotropin(β-hCG), progesterone (P), estradiol (E2)were measured in all 92 patients. Results: Incidence rates of the lack of BE, AIA and CTAin 92 cases were 60. 87%, 57. 61 % and 72.83% respectively. The lower levels of BE,AIA and CTA were elevated significantly (P< 0. 05 ～0. 01 ), and the serial levels β- hCG, P and E2 were markedly increasing (P< 0. 01 ) in all successful pregnant patients.The rate of the successful pregnancy of 92 cases was 89. 13 % (to TA 91. 67%, to RSA 88.24 % respectively). Conclusions: It suggeststhat the lack of blocking antibody (BA) andendocrine hormone deficiency may result inspontaneous abortion during early pregnancy.The therapeutic mechanism of those herbs intreating spontaneous abortion was associatedwith the growing levels of BA and hormone byregulating the maternal-fetal immunity and endocrine.

THE COMPARATIVE STUDY OF VENTILATED SUPER CAVITY SHAPE IN WATER TUNNEL AND INFINITE FLOW FIELD

In order to understand the difference of ventilated supercavity in water tunnel and infinite flow field, 3-D numerical simulations are carried out to obtain the ventilated supercavity in above mentioned conditions based on RANS equations, using the finite volume method and SST turbulence model in the framework of the two fluid multiphase flow model. The numerical method adopted in this article for the infinite flow field and water tunnel experiments is validated by comparing results with those of empirical formulas and experimental data. On this basis the difference between water tunnel experiments and infinite flow field is studied, including the influence of the route loss and the blocking effect in the water tunnel. Finally, some suggestions are made for water tunnel experiments.

Measurement errors and correction of the UAT-2 ultrasonic anemometer

Two kinds of measurement errors have been observed in the recently developed UAT-2 ultrasonic anemometer.One is the flow distortion produced by a"blocking effect",and the other is the angle of attack caused by the vertical misalignment of the instrument.Here,we study these errors and discuss the possible correction methods.Via a wind tunnel experiment and numerical simulation,a 3D calibration matrix was developed to correct the"blocking effect".In the field test,the angle of attack was detected by an inclinometer settled on the reference plane of the anemometer,and the instrumental misalignment or tilt was corrected by a coordinate transformation.The combined use of an inclinometer and the proposed correction method may help find a new approach for vertical velocity correction.

Particle-number-conserving analysis of multiquasiparticle bands in ^(177)Lu

The experimental one-, three-, and five-quasiparticle bands in 177Lu are analyzed by the particle-number conserving （PNC） method for treating the cranked shell model with pairing interaction, in which the blocking effects are taken into account exactly. The experimental moments of inertia are reproduced very well by PNC calculations with us free parameter.

Particle-number conserving analysis of the high-K multi-quasiparticle bands in ^(179)Re

The experimentally observed ten rotational bands in 179Re are analyzed with the particle-number conserving method for treating the cranked shell model with pairing interaction, in which the blocking effects are taken into account exactly. The experimental moments of inertia of these bands are reproduced quite well by our calculations with no free parameter and the deformation driving effects are discussed. The bandhead energies and the variation in the occupation probability of each cranked orbital are also analyzed.