In order to make the slag from desulphurization and slag skimming(SDSS)to be comprehensively recycled and utilized,a combined process of beneficiation and building materials preparation was proposed to recover iron fr...In order to make the slag from desulphurization and slag skimming(SDSS)to be comprehensively recycled and utilized,a combined process of beneficiation and building materials preparation was proposed to recover iron from SDSS,meanwhile to apply the remaining slag tailings as cement admixture.From this process,three iron-rich products were recovered in stages by clean gravity-magnetic separation,slag tailings were left.Slag powder was prepared by ultrafine grinding of slag tailings.The stability,setting time and cement mortar strength of the slag tailings cements(STC)which were mixed with Portland cement and slag powder were studied respectively.The results showed that a proper overall performance still could be obtained at the slag powder content of 30%.Chemical composition analysis,X-ray diffraction(XRD)analysis,metallographic microscope and scanning electron microscope(SEM)analysis were employed to assess the characteristics of the SDSS and the products obtained from the whole process.The results indicated that the three iron-rich products could be used as a raw material for steelmaking and ironmaking and the relatively large amount of calcium silicate(C_(2)S)and tricalcium silicate(C_(3)S)in the slag tailings make the addition of slag powder into the Portland cement feasible.展开更多
Celtis is a Cannabaceae genus of 60e70 species of trees,or rarely shrubs,commonly known as hackberries.This woody genus consists of very valuable forest plants that provide important wildlife habitat for birds and mam...Celtis is a Cannabaceae genus of 60e70 species of trees,or rarely shrubs,commonly known as hackberries.This woody genus consists of very valuable forest plants that provide important wildlife habitat for birds and mammals.Although previous studies have identified its phylogenetic position,interspecific relationships within Celtis remain unclear.In this study,we generated genome skimming data from five Celtis species to analyze phylogenetic relationships within the genus and develop genome resources.The plastomes of Celtis ranged in length from 158,989 bp to 159,082 bp,with a typical angiosperm quadripartite structure,and encoded a total of 132 genes with 20 duplicated in the IRs.Comparative analyses showed that plastome content and structure were relatively conserved.Whole plastomes showed no signs of gene loss,translocations,inversions,or genome rearrangement.Six plastid hotspot regions(trnH-psbA,psbA-trnK,trnG-trnR,psbC-trnS,cemA-petA and rps8-rpl14),4097 polymorphic nuclear SSRs,as well as 62 low or single-copy gene fragments were identified within Celtis.Moreover,the phylogenetic relationships based on the complete plastome sequences strongly endorse the placement of C.biondii as sister to the((((C.koraiensis,C.sinensis),C.tetrandra),C.julianae),C.cerasifera)clade.These findings and the genetic resources developed here will be conducive to further studies on the genus Celtis involving phylogeny,population genetics,and conservation biology.展开更多
This paper has proposed a new modelling and simulating technique for the echo of the semi-active radar seeker against the sea skimming target. The echo modelling is based on the electromagnetic scattering mechanisms. ...This paper has proposed a new modelling and simulating technique for the echo of the semi-active radar seeker against the sea skimming target. The echo modelling is based on the electromagnetic scattering mechanisms. A modified Four-path model based on the radar detection scene is used to describe the multipath scattering between the target and rough sea surface. A Facet-based Small Slope Approximation (FBSSA) method is employed to calculate the scattering from the sea surface. The Physical Optics (PO) and the Equivalent Edge Current (EEC) Method is used to calculate the target scattering. In the echo simulations. The results present the original echo and the echo processed by the signal processing procedures, where the clutter and multipath effect can be observed.展开更多
This paper deals with some aspects of the air entrainment process along the chute of spillway and study of pressure fluctuations. The experimental study has been carried out using stepped spillway model located in the...This paper deals with some aspects of the air entrainment process along the chute of spillway and study of pressure fluctuations. The experimental study has been carried out using stepped spillway model located in the campus of Government College of Engineering, Amravati (India). It is observed that air concentration is increasing with discharge as well as with number of step. Air concentration is increasing along the length of spillway. It is also observed that the bottom mean air concentration increases with step height in the upstream reach of stepped spillway, which is prone to cavitation. The pressure profiles exhibit a wavy pattern down the stepped chute and pressure on each step increases with ratio of critical depth to step height (yc/h).展开更多
As a widely used flood energy dissipator, the stepped spillway can significantly dissipate the kinetic or hydraulic energy due to the air-entrainment in skimming flow over the steps. The free-surface aeration involves...As a widely used flood energy dissipator, the stepped spillway can significantly dissipate the kinetic or hydraulic energy due to the air-entrainment in skimming flow over the steps. The free-surface aeration involves the sharp deformation of the free surface and the complex turbulent shear flows. In this study, the volume of fluid (VOF), mixture, and Eulerian methods are utilized to simulate the air-entrainment by coupling with the Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) turbulence models. The free surface deformation, air volume fraction, pressure, and velocity are compared for the three different numerical methods. Only the Eulerian+RANS method fails to capture the free-surface aeration. The air volume fraction predicted by the VOF+LES method best matches the experimental measurement, while the mixture+LES method predicts the inception point of the air entrainment more accurately.展开更多
This paper illustrates the similarity and dissimilarity between two basic reading skills- skimming and scanning from different ways.It advises readers to understand and make full use of them in their everyday reading....This paper illustrates the similarity and dissimilarity between two basic reading skills- skimming and scanning from different ways.It advises readers to understand and make full use of them in their everyday reading.They will make reading easier and help improve reading comprehension to a certain extent.展开更多
Numerical simulation of stepped channel flow was conducted using turbulence models based on the VOF technique. Stepped channel flow is a complicated air-water two-phase flow with free surface, which can be divided int...Numerical simulation of stepped channel flow was conducted using turbulence models based on the VOF technique. Stepped channel flow is a complicated air-water two-phase flow with free surface, which can be divided into three flow regimes: skimming flow, nappe flow and transition flow. The characteristics of skimming flow over mild stepped channel was investigated, including friction factors, air concentration profiles velocity field, clear-water and bulked depths, static pressure, etc. Smooth channel flow was also simulated to compare the hydraulic characteristics of the stepped channel flow with the smooth one. Comparisons between the computed and the measured were made. Furthermore, comparison of the computed air concentration with Straub and Anderson's data was also performed. The Fluent 6.1 software was employed to conduct this numerical simulation work.展开更多
This article intends to shed some light on effective use of three reading strategies: skimming,scanning and studying for non-English-speaking middle school students.The article also presents some advice for the teache...This article intends to shed some light on effective use of three reading strategies: skimming,scanning and studying for non-English-speaking middle school students.The article also presents some advice for the teacher's consideration when designing and preparing reading materials.展开更多
The rapid expansion of next-generation sequencing (NGS) has generated a powerful array of approaches to address fundamental questions in biology. Several genome-partitioning strategies to sequence selected subsets o...The rapid expansion of next-generation sequencing (NGS) has generated a powerful array of approaches to address fundamental questions in biology. Several genome-partitioning strategies to sequence selected subsets of the genome have emerged in the fields of phylogenomics and evolutionary genomics. In this review, we summarize the applications, advantages and limitations of four NGS-based genome- partitioning approaches in plant phylogenomics: genome skimming, transcriptome sequencing (RNA- seq), restriction site associated DNA sequencing (RAD-Seq), and targeted capture (Hyb-seq). Of these four genome-partitioning approaches, targeted capture (especially Hyb-seq) shows the greatest promise for plant phy^ogenetics over the next fex~ years. This reviex~ wi~ aid ~esea^chers in their selection of appropriate genome-partitioning approaches to address questions of evolutionary scale, where we anticipate continued development and expansion ofwhole-genome sequencing strategies in the fields of plant phylogenomics and evolutionary biology research.展开更多
Shibataea is a genus of temperate bamboos(Poaceae:Bambusoideae)endemic to China,but little is known about its phylogenetic position and interspecific relationships.To elucidate the phylogenetic relationship of the bam...Shibataea is a genus of temperate bamboos(Poaceae:Bambusoideae)endemic to China,but little is known about its phylogenetic position and interspecific relationships.To elucidate the phylogenetic relationship of the bamboo genus Shibataea,we performed genome-scale phylogenetic analysis of all seven species and one variety of the genus using double digest restriction-site associated DNA sequencing(dd RAD-seq)and whole plastid genomes generated using genome skimming.Our phylogenomic analyses based on dd RAD-seq and plastome data congruently recovered Shibataea as monophyletic.The nuclear data resolved S.hispida as the earliest diverged species,followed by S.chinensis,while the rest of Shibataea can be further divided into two clades.However,the plastid and nuclear topologies conflict significantly.By comparing the results of network analysis and topologies reconstructed from different datasets,we identify S.kumasasa as the most admixed species,which may be caused by incomplete lineage sorting(ILS)or interspecific gene flow with four sympatric species.This study highlights the power of dd RAD and plastome data in resolving complex relationships in the intractable bamboo genus.展开更多
The traditional medicinal plant,and endangered species Aristolochia delavayi(Aristolochiaceae)is an endemic species in China and occurs in the warm and dry areas along the Jinsha river.It is also a specific host of th...The traditional medicinal plant,and endangered species Aristolochia delavayi(Aristolochiaceae)is an endemic species in China and occurs in the warm and dry areas along the Jinsha river.It is also a specific host of the larvae of Byasa daemonius,a vulnerable butterfly.In this study,15 pairs of polymorphic microsatellite primers of A.delavayi were designed and screened based on the Simple Sequence Repeats(SSR)loci found by using the results of genome skimming.Based on these 15 SSR markers,the genetic diversity and structure of 193 individuals from ten natural populations were analyzed in detail.In comparison to other endemic and endangered plants in the region,the population of A.delavayi possess a relatively high genetic diversity(He=0.550,I=1.112).AMOVA analysis showed that 68.4%of the total genetic diversity was within populations and 31.6%of the variation occurred among populations.There was a significant genetic differentiation among natural populations of A.delavayi detectable,with low gene flow(Nm=0.591).This might be attributed to geographical barriers and limited seed dispersal.To test the isolation by distance(IBD),we performed Mantel test,which showed a significant correlation between the geographic and genetic distances.In order to cope with the possible biases caused by IBD,we additionally performed Bayesian genetic cluster analyses and principal coordinate analysis(PCoA).The final cluster analysis revealed three groups with distinct geographical distribution.Habitat fragmentation and limited gene flow between these populations may be the main reasons for the current genetic structure.For conservation of this species,we suggest to divide its populations into three protection management units,with subsequent focus on the Yongsheng and Luquan populations which experienced a genetic bottleneck event in the past.展开更多
How do you get information from an article as much and fast as possible while you are reading? It is a very important thing for us——Chinese readers. Reading is an important element in our English study. Mastering re...How do you get information from an article as much and fast as possible while you are reading? It is a very important thing for us——Chinese readers. Reading is an important element in our English study. Mastering reading skills will help increase our reading speed and comprehend what we read. Now several reading skills are to be discussed in this paper.展开更多
Pseudocerastium is a monotypic genus in Caryophyllaceae endemic to China.The genus has been widely accepted since it was described in 1998,however its phylogenetic position within Caryophyllaceae has never been studie...Pseudocerastium is a monotypic genus in Caryophyllaceae endemic to China.The genus has been widely accepted since it was described in 1998,however its phylogenetic position within Caryophyllaceae has never been studied.In the present study,the whole plastid genome and nuclear ribosomal internal transcribed spacer(ITS)sequences of Pseudocerastium stellarioides was obtained through genome skimming,and the phylogenetic position of the species was studied for the first time.Plastid phylogenomic analysis of Caryophyllaceae revealed that Pseudocerastium is clustered within the tribe Alsineae with strong support.Phylogenetic analyses based on an enlarged taxon sampling of Alsineae using five DNA regions(matK,rbcL,rps16 intron,trnL-F and ITS)revealed that P.stellarioides was nested deeply within Cerastium with strong support.Analyses of morphological character evolution suggest that the ancestral states in Alsineae include three styles and a six-lobed capsule at the apex,while both Cerastium and Pseudocerastium have five styles and ten lobes at the apex of the capsule,further supporting their close relationship.The species Pseudocerastium stellarioides is similar to Cerastium wilsonii in morphology,but differs in having villous indumentum on the lower part of the filaments and compressed globose seeds.Therefore,based on the present molecular and morphological evidence,the generic name Pseudocerastium is reduced here as a new synonym of Cerastium and the species P.stellarioides is transferred to Cerastium as C.jiuhuashanense.展开更多
Over recent years, there has been a clear increase in the frequency of reported flooding events around the world. Gabion structures offer one means of flood mitigation in dam spillways. These types of structures provi...Over recent years, there has been a clear increase in the frequency of reported flooding events around the world. Gabion structures offer one means of flood mitigation in dam spillways. These types of structures provide an additional challenge to the computational modeller in that flow through the porous gabions must be simulated. We have used a computational model to investigate the flow over gabion stepped spillways. The model was first validated against published experimental results. Then, gabion stepped spillways with four different step geometries were tested under the same conditions in order to facilitate inter-comparisons and to choose the best option in terms of energy dissipation. The results show that normal gabion steps can dissipate more energy than overlap, inclined, and pooled steps. An intensive set of tests with varying slope, stone size, and porosity were undertaken. The location of the inception point and the water depth at this point obtained from this study were compared with those from existing formulae. Two new empirical equations have been derived, on the basis of a regression analysis, to provide improved results for gabion stepped spillways.展开更多
基金The authors gratefully acknowledge the National Key Research and Development Program of China(No.2018YFC1901902)the Liao Ning Revitalization Talents Program(No.XLYC1907162).
文摘In order to make the slag from desulphurization and slag skimming(SDSS)to be comprehensively recycled and utilized,a combined process of beneficiation and building materials preparation was proposed to recover iron from SDSS,meanwhile to apply the remaining slag tailings as cement admixture.From this process,three iron-rich products were recovered in stages by clean gravity-magnetic separation,slag tailings were left.Slag powder was prepared by ultrafine grinding of slag tailings.The stability,setting time and cement mortar strength of the slag tailings cements(STC)which were mixed with Portland cement and slag powder were studied respectively.The results showed that a proper overall performance still could be obtained at the slag powder content of 30%.Chemical composition analysis,X-ray diffraction(XRD)analysis,metallographic microscope and scanning electron microscope(SEM)analysis were employed to assess the characteristics of the SDSS and the products obtained from the whole process.The results indicated that the three iron-rich products could be used as a raw material for steelmaking and ironmaking and the relatively large amount of calcium silicate(C_(2)S)and tricalcium silicate(C_(3)S)in the slag tailings make the addition of slag powder into the Portland cement feasible.
基金supported by the National Natural Science Foundation of China(Grant Nos.31900188,31970225)Natural Science Foundation of Zhejiang Province(Grant No.LY19C030007).
文摘Celtis is a Cannabaceae genus of 60e70 species of trees,or rarely shrubs,commonly known as hackberries.This woody genus consists of very valuable forest plants that provide important wildlife habitat for birds and mammals.Although previous studies have identified its phylogenetic position,interspecific relationships within Celtis remain unclear.In this study,we generated genome skimming data from five Celtis species to analyze phylogenetic relationships within the genus and develop genome resources.The plastomes of Celtis ranged in length from 158,989 bp to 159,082 bp,with a typical angiosperm quadripartite structure,and encoded a total of 132 genes with 20 duplicated in the IRs.Comparative analyses showed that plastome content and structure were relatively conserved.Whole plastomes showed no signs of gene loss,translocations,inversions,or genome rearrangement.Six plastid hotspot regions(trnH-psbA,psbA-trnK,trnG-trnR,psbC-trnS,cemA-petA and rps8-rpl14),4097 polymorphic nuclear SSRs,as well as 62 low or single-copy gene fragments were identified within Celtis.Moreover,the phylogenetic relationships based on the complete plastome sequences strongly endorse the placement of C.biondii as sister to the((((C.koraiensis,C.sinensis),C.tetrandra),C.julianae),C.cerasifera)clade.These findings and the genetic resources developed here will be conducive to further studies on the genus Celtis involving phylogeny,population genetics,and conservation biology.
文摘This paper has proposed a new modelling and simulating technique for the echo of the semi-active radar seeker against the sea skimming target. The echo modelling is based on the electromagnetic scattering mechanisms. A modified Four-path model based on the radar detection scene is used to describe the multipath scattering between the target and rough sea surface. A Facet-based Small Slope Approximation (FBSSA) method is employed to calculate the scattering from the sea surface. The Physical Optics (PO) and the Equivalent Edge Current (EEC) Method is used to calculate the target scattering. In the echo simulations. The results present the original echo and the echo processed by the signal processing procedures, where the clutter and multipath effect can be observed.
文摘This paper deals with some aspects of the air entrainment process along the chute of spillway and study of pressure fluctuations. The experimental study has been carried out using stepped spillway model located in the campus of Government College of Engineering, Amravati (India). It is observed that air concentration is increasing with discharge as well as with number of step. Air concentration is increasing along the length of spillway. It is also observed that the bottom mean air concentration increases with step height in the upstream reach of stepped spillway, which is prone to cavitation. The pressure profiles exhibit a wavy pattern down the stepped chute and pressure on each step increases with ratio of critical depth to step height (yc/h).
基金supported by the Guangdong Special Research Fund of Public Welfare and Capacity Building(2015A020216008)the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund(the second phase)
文摘As a widely used flood energy dissipator, the stepped spillway can significantly dissipate the kinetic or hydraulic energy due to the air-entrainment in skimming flow over the steps. The free-surface aeration involves the sharp deformation of the free surface and the complex turbulent shear flows. In this study, the volume of fluid (VOF), mixture, and Eulerian methods are utilized to simulate the air-entrainment by coupling with the Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) turbulence models. The free surface deformation, air volume fraction, pressure, and velocity are compared for the three different numerical methods. Only the Eulerian+RANS method fails to capture the free-surface aeration. The air volume fraction predicted by the VOF+LES method best matches the experimental measurement, while the mixture+LES method predicts the inception point of the air entrainment more accurately.
文摘This paper illustrates the similarity and dissimilarity between two basic reading skills- skimming and scanning from different ways.It advises readers to understand and make full use of them in their everyday reading.They will make reading easier and help improve reading comprehension to a certain extent.
文摘Numerical simulation of stepped channel flow was conducted using turbulence models based on the VOF technique. Stepped channel flow is a complicated air-water two-phase flow with free surface, which can be divided into three flow regimes: skimming flow, nappe flow and transition flow. The characteristics of skimming flow over mild stepped channel was investigated, including friction factors, air concentration profiles velocity field, clear-water and bulked depths, static pressure, etc. Smooth channel flow was also simulated to compare the hydraulic characteristics of the stepped channel flow with the smooth one. Comparisons between the computed and the measured were made. Furthermore, comparison of the computed air concentration with Straub and Anderson's data was also performed. The Fluent 6.1 software was employed to conduct this numerical simulation work.
文摘This article intends to shed some light on effective use of three reading strategies: skimming,scanning and studying for non-English-speaking middle school students.The article also presents some advice for the teacher's consideration when designing and preparing reading materials.
基金supported by the Large-scale Scientific Facilities of the Chinese Academy of Sciences (Grant No: 2017-LSFGBOWS-01)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB31000000)the Program of Science and Technology Talents Training of Yunnan Province (2017HA014)
文摘The rapid expansion of next-generation sequencing (NGS) has generated a powerful array of approaches to address fundamental questions in biology. Several genome-partitioning strategies to sequence selected subsets of the genome have emerged in the fields of phylogenomics and evolutionary genomics. In this review, we summarize the applications, advantages and limitations of four NGS-based genome- partitioning approaches in plant phylogenomics: genome skimming, transcriptome sequencing (RNA- seq), restriction site associated DNA sequencing (RAD-Seq), and targeted capture (Hyb-seq). Of these four genome-partitioning approaches, targeted capture (especially Hyb-seq) shows the greatest promise for plant phy^ogenetics over the next fex~ years. This reviex~ wi~ aid ~esea^chers in their selection of appropriate genome-partitioning approaches to address questions of evolutionary scale, where we anticipate continued development and expansion ofwhole-genome sequencing strategies in the fields of plant phylogenomics and evolutionary biology research.
基金supported by the National Natural Science Foundation of China (Grant No. 31470322 and 31430011)
文摘Shibataea is a genus of temperate bamboos(Poaceae:Bambusoideae)endemic to China,but little is known about its phylogenetic position and interspecific relationships.To elucidate the phylogenetic relationship of the bamboo genus Shibataea,we performed genome-scale phylogenetic analysis of all seven species and one variety of the genus using double digest restriction-site associated DNA sequencing(dd RAD-seq)and whole plastid genomes generated using genome skimming.Our phylogenomic analyses based on dd RAD-seq and plastome data congruently recovered Shibataea as monophyletic.The nuclear data resolved S.hispida as the earliest diverged species,followed by S.chinensis,while the rest of Shibataea can be further divided into two clades.However,the plastid and nuclear topologies conflict significantly.By comparing the results of network analysis and topologies reconstructed from different datasets,we identify S.kumasasa as the most admixed species,which may be caused by incomplete lineage sorting(ILS)or interspecific gene flow with four sympatric species.This study highlights the power of dd RAD and plastome data in resolving complex relationships in the intractable bamboo genus.
基金Support for this study was provided by grants from the NSFC(National Natural Science Foundation of China)-Yunnan Joint fund to support key projects(No.U1602264)Yunnan Ten Thousand Talents Plan Young&Elite Talent Project to G.Chen(YNWR-QNBJ-2018-017)+2 种基金NSFC(National Natural Science Foundation of China)(No.31660057)Y.P.GengScience&Technology Basic Resources Investigation Program of China for Survey and Germplasm Conservation of PSESP in Southwest China(2017FY100100)to W.B.Sun.
文摘The traditional medicinal plant,and endangered species Aristolochia delavayi(Aristolochiaceae)is an endemic species in China and occurs in the warm and dry areas along the Jinsha river.It is also a specific host of the larvae of Byasa daemonius,a vulnerable butterfly.In this study,15 pairs of polymorphic microsatellite primers of A.delavayi were designed and screened based on the Simple Sequence Repeats(SSR)loci found by using the results of genome skimming.Based on these 15 SSR markers,the genetic diversity and structure of 193 individuals from ten natural populations were analyzed in detail.In comparison to other endemic and endangered plants in the region,the population of A.delavayi possess a relatively high genetic diversity(He=0.550,I=1.112).AMOVA analysis showed that 68.4%of the total genetic diversity was within populations and 31.6%of the variation occurred among populations.There was a significant genetic differentiation among natural populations of A.delavayi detectable,with low gene flow(Nm=0.591).This might be attributed to geographical barriers and limited seed dispersal.To test the isolation by distance(IBD),we performed Mantel test,which showed a significant correlation between the geographic and genetic distances.In order to cope with the possible biases caused by IBD,we additionally performed Bayesian genetic cluster analyses and principal coordinate analysis(PCoA).The final cluster analysis revealed three groups with distinct geographical distribution.Habitat fragmentation and limited gene flow between these populations may be the main reasons for the current genetic structure.For conservation of this species,we suggest to divide its populations into three protection management units,with subsequent focus on the Yongsheng and Luquan populations which experienced a genetic bottleneck event in the past.
文摘How do you get information from an article as much and fast as possible while you are reading? It is a very important thing for us——Chinese readers. Reading is an important element in our English study. Mastering reading skills will help increase our reading speed and comprehend what we read. Now several reading skills are to be discussed in this paper.
基金the Natural Science Foundation of Guangdong Province,China(2019A1515011695)the National Natural Science Foundation of China(31500180).
文摘Pseudocerastium is a monotypic genus in Caryophyllaceae endemic to China.The genus has been widely accepted since it was described in 1998,however its phylogenetic position within Caryophyllaceae has never been studied.In the present study,the whole plastid genome and nuclear ribosomal internal transcribed spacer(ITS)sequences of Pseudocerastium stellarioides was obtained through genome skimming,and the phylogenetic position of the species was studied for the first time.Plastid phylogenomic analysis of Caryophyllaceae revealed that Pseudocerastium is clustered within the tribe Alsineae with strong support.Phylogenetic analyses based on an enlarged taxon sampling of Alsineae using five DNA regions(matK,rbcL,rps16 intron,trnL-F and ITS)revealed that P.stellarioides was nested deeply within Cerastium with strong support.Analyses of morphological character evolution suggest that the ancestral states in Alsineae include three styles and a six-lobed capsule at the apex,while both Cerastium and Pseudocerastium have five styles and ten lobes at the apex of the capsule,further supporting their close relationship.The species Pseudocerastium stellarioides is similar to Cerastium wilsonii in morphology,but differs in having villous indumentum on the lower part of the filaments and compressed globose seeds.Therefore,based on the present molecular and morphological evidence,the generic name Pseudocerastium is reduced here as a new synonym of Cerastium and the species P.stellarioides is transferred to Cerastium as C.jiuhuashanense.
基金supported by the Higher Committee for Education Development(HCED)in Iraq
文摘Over recent years, there has been a clear increase in the frequency of reported flooding events around the world. Gabion structures offer one means of flood mitigation in dam spillways. These types of structures provide an additional challenge to the computational modeller in that flow through the porous gabions must be simulated. We have used a computational model to investigate the flow over gabion stepped spillways. The model was first validated against published experimental results. Then, gabion stepped spillways with four different step geometries were tested under the same conditions in order to facilitate inter-comparisons and to choose the best option in terms of energy dissipation. The results show that normal gabion steps can dissipate more energy than overlap, inclined, and pooled steps. An intensive set of tests with varying slope, stone size, and porosity were undertaken. The location of the inception point and the water depth at this point obtained from this study were compared with those from existing formulae. Two new empirical equations have been derived, on the basis of a regression analysis, to provide improved results for gabion stepped spillways.