Corrigendum to “Uniform and graded bed-load sediment transport in a degrading channel with non-equilibrium conditions” [International Journal of Sediment Research 35 (2020) 115e124/04-258]’

The authors regret that the affiliation and email address of the corresponding author Khabat Khosravi in the published article is incorrect and the correct affiliation and email address should read as below.Khabat Khosravi Sari Agricultural Science and Natural Resources University,Sari,4818168984,Iran khabat.khosravi@gmail.com The authors would like to apologise for any inconvenience caused.     

A computational study of the role of particle size standard deviation on the collision frequency in differential settling

The results of a simple computational model for differential settling are presented illustrating the significant role that particle size distribution plays in collision frequency and sedimentation rate of particles in a quiescent environment. The model tracks a large number of particles(order 10~5) with log-normally distributed diameters,as they settle at their Stokes settling velocities.Particle collisions are detected and result in larger particles that fall more rapidly.A number of simplifying assumptions are made in the model in order to avoid empirical correlations for phenomena such as collision efficiency and particle shape.These simplifying assumptions were needed to isolate and quantify the role of the particle size distribution.Simulated concentration profiles indicate that,even in the absence of collisions, the standard deviation(σ_D) of the particle size strongly influences the bulk mass settling rate as,for largerσ_D, more mass is concentrated in larger,faster falling particles.The collision frequency is also a strong function ofσ_D. For a given mass concentration the collision frequency first increases linearly with increasingσ_D as greater variation in particle size leads to greater variation in particle velocity,and shorter times for particles to catch each other.For largerσ_D more mass is concentrated in larger particles,so,for a given mass concentration,there are fewer particles per unit volume,increasing the mean distance between the particles and reducing the collision frequency.The implications of these results for sedimentation measurement using optical attenuation techniques are discussed.     

Coupled estimation of the energy slope and associated sand-silt transport during high stream power events in alluvial rivers

A coupled routing for the transport capacity and the energy slope is introduced through the definition of the control factor m whose value is linked to the bed form configuration.The coupling aims to further incorporate the interactions occurring in alluvial rivers and thus enhance the prediction of the fine sediment fluxes,especially during high stream power events.Based on a predictive rule for the control factor m that only involves water depth,velocity and bedform constitutive texture,the novel method is confronted to observations collected in one of the most strongly dynamic alluvial river namely the Lower Yellow River.Comparisons between time series of measured and computed concentrations illustrate that during high velocity events the main dynamics of the sediment transport is correctly reproduced.The main advantage of the present approach is to supply consistent time evolutions of sediment concentrations without making use of any detailed shear information.     

DEFPOS and Its First Results

A spectrometer was built to examine the interstellar medium (ISM) using the hydrogen Balmer a line. It is called Dual Etalon Fabry-Perot Optical Spectrometer (DEFPOS). DEFPOS will be coupled to coude exit of the 150 cm telescope (RTT150) installed at TUBITAK National Observatory (TUG). DEFPOS was ready for observations about two years ago, but work was still continuing on the RTT150 coude exit alignment. So we have started observing HII regions with DEFPOS without the RTT150. We present here some characteristics of the instrument and some of the results obtained.     

Zonal character of failure near the wells and openings in high depth conditions

Rock mass failure on the high depth near the underground openings often has zonal character. The mechanism of this phenomenon consists in the periodical character of stresses in surrounding rock mass and developing of tensile macrocracks at the places （zones） of maximum tangentional stresses. Mathematical model of the high stressed rock mass is developed on the base of the defect media mechanics and nonequilibrium thermodynamics principals. The correspondence between the experimental research of faulted zonal structures near the high depths openings and mathematical model calculation is achieved. Relationships between the width of cracking zones and rock mass strength property have been determined.     

内蒙古二连盆地巴彦宝力格煤田下白垩统赛汉塔拉组层序—古地理与聚煤作用

二连盆地巴彦宝力格煤田蕴藏着丰富的煤炭和煤层气资源。利用钻孔和测井资料对赛汉塔拉组层序格架下的古地理演化特征和聚煤作用进行研究,识别出3种层序界面类型:区域不整合面、河道下切谷冲刷面和对应整合面,将赛汉塔拉组划分为2个三级层序,厚煤层主要发育于层序Ⅰ湖侵体系域早期和晚期。采用单因素分析多因素综合作图法,恢复了层序格架下的古地理格局,古地理单元为冲积扇、扇三角洲平原和滨浅湖。有利聚煤环境为扇三角洲平原与滨浅湖过渡带、滨浅湖,具有合适的基底沉降速率并且受到较小的陆源碎屑影响。从层序Ⅰ到层序Ⅱ,煤层厚度减小,聚煤作用减弱;多层厚煤层的形成受基底沉降震荡性、周期性的影响,受可容空间增加速率与泥炭堆积速率比值不断变化的控制。层序Ⅰ发育时期,研究区中部为下一步煤炭资源和煤层气勘探的有利区。