The West Lake area and water system in West Lake scenic area of Hangzhou City directly affect the soil properties of waterfront lawn beds,which in turn have a significant impact on the growth of waterfront lawns.In or...The West Lake area and water system in West Lake scenic area of Hangzhou City directly affect the soil properties of waterfront lawn beds,which in turn have a significant impact on the growth of waterfront lawns.In order to further improve the quality of lawns,the conditions of 10 waterfront lawn beds in West Lake scenic area were tested and analyzed.The results showed that the waterfront lawn beds in West Lake scenic area were prone to salinization,with moderate or high pH values,moderate overall organic matter content,relatively sufficient nitrogen and phosphorus elements,and relatively deficient potassium elements.The contents of exchangeable calcium in all samples were higher than the lower limit,and the contents of exchangeable sodium,exchangeable magnesium,and available manganese in the soil were moderate or low,while the contents of available copper were moderate or high.展开更多
Seagrass beds are crucial coastal ecosystems,functioning as vital blue carbon sinks and natural ecological barriers.However,these ecosystems are increasingly threatened by global climate events,coastal development,and...Seagrass beds are crucial coastal ecosystems,functioning as vital blue carbon sinks and natural ecological barriers.However,these ecosystems are increasingly threatened by global climate events,coastal development,and water eutrophication,making them some of the most endangered ecosystems worldwide.In the Yellow Sea and Bohai Sea regions,seagrass bed assessment and monitoring have been largely overlooked.Thus,strengthening research efforts is necessary to identify current distribution patterns and long-term changes in seagrass bed resources.This study focused on a seagrass bed in Sanggou Bay,Rongcheng,using remote sensing(RS)and geographic information system technologies to analyze multisource satellite data from the US Landsat and Chinese resource satellite series.By combining RS indexes with historical survey data,large-scale temporal and geographic distribution data for seagrass beds were obtained in the study area from 1985 to 2022.The spatial distribution and evolution trends of the seagrass bed were analyzed using a water depth inversion model,and the factors driving its degradation were identified.Results indicated that the seagrass bed area in Sanggou Bay fluctuated between 100 and 140 km^(2) from 1985 to 2010.During 2010–2013,dynamic changes in the seagrass bed area increased,with a considerable decrease in its overall size.After 2014,changes were minimal,indicating a notably stable state.Seagrass bed degradation in Sanggou Bay is influenced by high-intensity human activities,pollution from coastal land sources,raft cultures,underwater terrain conditions,and sedimentary environmental factors.The findings offer essential insights for developing seagrass restoration and protection strategies in Sanggou Bay and contribute to the broader scientific efforts for coastal ecosystem conservation and rehabilitation.展开更多
Cracking of early-age concrete can occur in the track beds of high-speed railways due to changes in material properties,environmental effects,and construction processes.This is a multi-field,time-varying issue involvi...Cracking of early-age concrete can occur in the track beds of high-speed railways due to changes in material properties,environmental effects,and construction processes.This is a multi-field,time-varying issue involving hydro-thermo-chemo-mechanical coupling.However,to date,research has not adequately described the early-age cracking mechanisms in track beds,and few risk control measures have been proposed.To solve this problem,we incorporated the hydration degree of concrete into multi-field coupling equations for early-age concrete,and set boundary conditions that account for environmental influences and various stress factors that typically cause early creep of concrete.A four-field coupled risk prediction model was built based on hydro-thermo-chemo-mechanical properties,and was used to calculate and analyze various time-varying behavior(including the risk and form of cracking)in the hydro,thermo,chemo,and mechanical fields of early-age concrete.Finally,we focused on material-related factors(maximum heat of hydration and peak heat release time),environmental factors(temperature difference between day and night,average daily cooling rate,and intensity of solar radiation),and construction technique factors(molding temperature,pouring time,and thermal insulation coefficient).The influence of these factors on the early-age cracking risk of the track bed was analyzed,and risk control measures against early cracking were proposed accordingly.展开更多
Over the past two decades,it has become increasingly apparent that early Mars may once have been warmer,wetter and more habitable for microbial life than it is today,which has spurred discussions about potential biosi...Over the past two decades,it has become increasingly apparent that early Mars may once have been warmer,wetter and more habitable for microbial life than it is today,which has spurred discussions about potential biosignatures that may be preserved in Martian sediments.An impediment to this line of research is the pervasive oxidation of Mars’surface due to photochemical oxidants that have likely destroyed remnants of organic matter.Here,we investigate whether nitrogen(N)transferred from biomass to phyllosilicate minerals during diagenesis can be preserved in oxidized mudrocks.We investigate two sequences of terrestrial Proterozoic red beds,namely the Sibley Group(1.4 Ga)in Canada and the Stoer Group(1.2 Ga)in Scotland,and we find enrichments in authigenic N in the range of several tens of ppm in both units.The highest concentrations(ca.100 ppm on average)are found in the most desiccated red beds of the Stoer Group,concurrent with enrichments in potassium(K).We discuss similarities and differences between the two sets of rocks with regards to salinity,pH,biological productivity and K-metasomatism,and we conclude that the ideal mechanism for the preservation of biogenic N in red beds may be in-situ release of ammonium from microbial mats into the clay substrate,possibly facilitated by early diagenetic,biologically induced illitization.Illite and smectite have been observed on Mars,and experiments suggest that Martian waters contained moderate amounts of dissolved K.Hence,it is conceivable that a similar K and N enrichment process could have occurred as to what we document for the Proterozoic,preserving evidence of life that may have survived to the modern day.展开更多
This work synthesized a series of Ni/CeO_(2)/Al_(2)O_(3) catalysts with varying CeO_(2) doping amounts to enhance low-temperature CO_(2) methanation.The introduction of CeO_(2) weakens the interaction between Ni and A...This work synthesized a series of Ni/CeO_(2)/Al_(2)O_(3) catalysts with varying CeO_(2) doping amounts to enhance low-temperature CO_(2) methanation.The introduction of CeO_(2) weakens the interaction between Ni and Al_(2)O_(3),leading to the formation of Ni-CeO_(2) active sites.This results in a high dispersion of Ni and CeO_(2),improved catalyst reducibility,increased number of active sites,and enhanced the CO_(2) methanation.This work further investigated the impact of WHSV and catalyst stacking configuration to enhance the reaction.When the catalyst is stacked into three segments with a temperature gradient of 330℃,300℃,and 250℃under WHSV=9000 ml·h^(-1)·g^(-1),the CO_(2) conversion significantly increases to 95%,which is remarkably close to the thermodynamic equilibrium(96%).展开更多
This work investigates the influence of the type sludge on drainage, plant development, purification performances and biosolids quality. Drainage properties were measured through the frequency of clogging, the percent...This work investigates the influence of the type sludge on drainage, plant development, purification performances and biosolids quality. Drainage properties were measured through the frequency of clogging, the percentage of leachate recovered and the dryness of accumulated sludge. Plant development was measured through the density, the height and the stem diameter. Purification performance was evaluated from the reduction rate. Biosolids quality was measured after 3 months of maturation. The results show that the clogging frequencies were 9.5%;0% and 3.7%;the volume of leachate recovered was 42.2%;20.4% and 24.7% and, the dryness was 33.4%;61.1% and 52.4% for FS-ST, FS-STT and SS respectively. Plants densities were about, with densities 197.1, 171.3 and 178.3 plants/m2 in beds fed respectively with FS-ST, FS-STT and SS. Despite the high removal rates, the concentrations of pollutants in the leachates are above the Senegalese standard NS 05-061 for discharge into the environment. The biosolids are all mature with C/N and NH4+/NO3?ratios lower than 12 and 1 respectively. The biosolids are also rich in organic and mineral elements. The concentrations of Ascaris eggs are higher than the WHO recommendations. These biosolids should be stored for additional time or composted.展开更多
Elucidating the flow features around piles in local scouring processes is crucial for studies of local scouring mechanisms and scour depth estimates.This study details the flow turbulence characteristics of two submer...Elucidating the flow features around piles in local scouring processes is crucial for studies of local scouring mechanisms and scour depth estimates.This study details the flow turbulence characteristics of two submerged piles that are determined by solving the Navier-Stokes equations with the improved delayed detached eddy simulation model.This model is verified by comparing experimental and numerical results for hydrodynamic parameters with the literature for both square-crossing piles(SCPs)and circular-crossing piles(CCPs).Original topographies of flat and scoured beds(i.e.,the initial and equilibrium scouring stages)are based on experimental results obtained by the authors in the present paper.SCP and CCP flow features in the scouring process are discussed.The results indicate that during the scouring process,the time-averaged drag coefficient and root mean square(rms)of the lift coefficient increase linearly in the CCP test,while the rms of the lift coefficient in the SCP test decreases linearly.Moreover,the minimum pressure coefficient is always located in the upstream corners in the SCP case but moves from 72.5°to 79.5°when the scour hole is completely developed in the CCP case.Downward flow behind the pile,which is generated by separated boundary layers above the top face of the pile,can reach the sand bed and turn the separated shear layers into patches of small vortices in the near-wake regions.Thus,the high shear stress zones are mainly at the scour edges under scoured-bed conditions.展开更多
As a high-performance material with great application potential,the application of carbon nanotubes has been limited by their production volume.A distributor-less conical fluidized bed is the main equipment used in th...As a high-performance material with great application potential,the application of carbon nanotubes has been limited by their production volume.A distributor-less conical fluidized bed is the main equipment used in the industrial production of carbon nanotubes.To improve the production volume and product quality of carbon nanotubes,the study of fluidized-bed-diameter scaling is important.Three different diameters of distributor-less conical fluidized beds were established,and then the particle behavior and bubble characteristics of carbon nanotube clusters at these bed diameters were investigated.Time-series and wavelet analysis methods were used to analyze the pressure-fluctuation signals inside the fluidized beds.Results showed that the distributor-less design caused the airflow to break through the middle of the bed,which did not change with the change in bed diameter.The powder-bridging phenomenon of carbon nanotube clusters in a 100-mm-diameter fluidized bed was related to the special microstructure of carbon nanotube clusters.The frequency of pressure fluctuations in the bed decreased nonlinearly with increasing bed diameter.This study can guide the design and scale-up of distributor-less conical fluidized beds,especially for the scale-up of carbon nanotube production equipment,which can contribute to the improvement of carbon nanotubes’capacity and quality in industrial production.展开更多
The understanding of the gas-liquid flow characteristics in a micro-packed bed reactor is still immature,especially for many gas-organic working systems commonly used in industry.Accordingly,this study proposes a plat...The understanding of the gas-liquid flow characteristics in a micro-packed bed reactor is still immature,especially for many gas-organic working systems commonly used in industry.Accordingly,this study proposes a platform to investigate the gas-eliquid flow characteristics in a micro-packed bed reactor and presents a unified expression for these characteristics of both organic and aqueous liquid phase.The influence of two-phase flow rate,working solution viscosity,and packing particle size on the liquid holdup and pressure drop were studied.The gas-organic working systems results show that the liquid holdup ranges between 0.5 and 0.8 and pressure drop ranges from 50 to 350 kPa·m^(-1).In particular,a strong correlation between the two flow characteristics parameters(liquid holdup and pressure drop)was proposed for the first time.Finally,a general pressure drop mathematical prediction model in micropacked bed were developed.展开更多
We have proposed a new mathematical method,the SEIHCRD model,which has an excellent potential to predict the incidence of COVID-19 diseases.Our proposed SEIHCRD model is an extension of the SEIR model.Three-compartmen...We have proposed a new mathematical method,the SEIHCRD model,which has an excellent potential to predict the incidence of COVID-19 diseases.Our proposed SEIHCRD model is an extension of the SEIR model.Three-compartments have added death,hospitalized,and critical,which improves the basic understanding of disease spread and results.We have studiedCOVID-19 cases of six countries,where the impact of this disease in the highest are Brazil,India,Italy,Spain,the United Kingdom,and the United States.After estimating model parameters based on available clinical data,the modelwill propagate and forecast dynamic evolution.Themodel calculates the Basic reproduction number over time using logistic regression and the Case fatality rate based on the selected countries’age-category scenario.Themodel calculates two types of Case fatality rate one is CFR daily,and the other is total CFR.The proposed model estimates the approximate time when the disease is at its peak and the approximate time when death cases rarely occur and calculate how much hospital beds and ICU beds will be needed in the peak days of infection.The SEIHCRD model outperforms the classic ARXmodel and the ARIMA model.RMSE,MAPE,andRsquaredmatrices are used to evaluate results and are graphically represented using Taylor and Target diagrams.The result shows RMSE has improved by 56%–74%,and MAPE has a 53%–89%improvement in prediction accuracy.展开更多
Methods and procedures of three-dimensional （3D） characterization of the pore structure features in the packed ore particle bed are focused. X-ray computed tomography was applied to deriving the cross-sectional imag...Methods and procedures of three-dimensional （3D） characterization of the pore structure features in the packed ore particle bed are focused. X-ray computed tomography was applied to deriving the cross-sectional images of specimens with single particle size of 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10 ram. Based on the in-house developed 3D image analysis programs using Matlab, the volume porosity, pore size distribution and degree of connectivity were calculated and analyzed in detail. The results indicate that the volume porosity, the mean diameter of pores and the effective pore size （d50） increase with the increasing of particle size. Lognormal distribution or Gauss distribution is mostly suitable to model the pore size distribution. The degree of connectivity investigated on the basis of cluster-labeling algorithm also increases with increasing the particle size approximately.展开更多
Lacustrine deposits exposed at Daohugou, Inner Mongolia, China, have yielded superbly preserved vertebrate fossils. The fossil beds were first misinterpreted as of Early Cretaceous age, based on alleged occurrences of...Lacustrine deposits exposed at Daohugou, Inner Mongolia, China, have yielded superbly preserved vertebrate fossils. The fossil beds were first misinterpreted as of Early Cretaceous age, based on alleged occurrences of key fossils of the Jehol Biota. Compelling evidence revealed by more rigorous research involving regional biostratigraphy, radiometric dating, and paleontology supports the Middle Jurassic age of the fossil beds. Despite the awesome evidence for the Middle Jurassic age of the Daohugou beds, the age dispute has been resurrected recently by invoking an overturned stratigraphic sequence. A careful review of the data, however, found no evidence that this sequence has been overturned. In addition, many of the assumptions, on which the conjecture of the fossil beds being post- Middle Jurassic is imprudently based, are self-contradictory or otherwise misleading. Thus, the post- Middle Jurassic age of the Daohugou beds as an unfounded conclusion can readily be dismissed.展开更多
The planktic foraminifera of the Chuangde Formation （Upper Cretaceous Oceanic Red Beds, CORBs） as exposed at Tianbadong section, Kangmar, southern Tibet has been firstly studied for a detailed for a detailed biostra...The planktic foraminifera of the Chuangde Formation （Upper Cretaceous Oceanic Red Beds, CORBs） as exposed at Tianbadong section, Kangmar, southern Tibet has been firstly studied for a detailed for a detailed biostratigraphy elaboration. A rich and well-preserved planktic foraminifera were recovered from the Chuangde Formation of the Tianbadong section and the Globotruncanita elevata, Globotruncana ventricosa, Radotruncana calcarata, Globotruncanella havanensis, Globotruncana aegyptiaca, Gansserina gansseri and Abathomphalus mayaroensis zones have been recognized. The planktic foraminiferal assemblage points to an early Campanian to Maastrichitian age for the CORBs of the eastern North Tethyan Himalayan sub-belt, which also provides a better understanding of the shifting progress of the Indian Plate to the north and the evolution of the Neotethyan ocean. The lithostratigraphy of the Chuangde Formation of the Tianbadong section comprises two lithological sequences observed in ascending succession： a lower unit （the Shale Member） mainly composed of purple （cherry-red, violet-red） shales with interbedded siltstones and siliceous rocks; and an upper unit （the Limestone Member） of variegated limestones. The strata of the Chuangde Formation in the Tianbadong section are similar to CORBs in other parts of the northern Tethyan Himalaya area of Asia （Gyangze, Sa＇gya, Sangdanlin, northern Zanskar, etc.）. The fossil contents of the Chuangde Formation in the sections （CORBs） studied provide a means of correlation with the zonation schemes for those of the northern Tethyan Himalayan sub-belt and the Upper Cretaceous of the southern Tethyan Himalayan sub-belt. Paleogeographic reconstruction for the Late Cretaceous indicates that the Upper Cretaceous Chuangde Formation （CORBs） and correlatable strata in northern Zanskar were representative of slope to basinal deposits, which were situated in the northern Tethyan Belt. Correlatable Cretaceous strata in Spiti and Gamba situated in the southern Tethyan Belt in contrast were deposited in shelf environments along the Tethyan Himalayan passive margin. CORBs are most likely formed by the oxidation of Fe（II）-enriched, anoxic deep ocean water near the chemocline that separated the oxic oceanic surface from the anoxic.展开更多
Based on the subdivision into three members of the Lower Cretaceous Jiufotang Formation in western Liaoning, this paper deals mainly with the division and correlation of precious fossil birdand reptile-bearing beds of...Based on the subdivision into three members of the Lower Cretaceous Jiufotang Formation in western Liaoning, this paper deals mainly with the division and correlation of precious fossil birdand reptile-bearing beds of the formation in the Dachengzi, Chaoyang, Dapingfang.Meileyingzi and Fuxin-Yixian basins. Among them, the precious fossil-bearing beds in the Dachengzi Basin may be recognized as the Xidagou Bed of the second member and the Yangcaogoudonggou Bed of the third member; those in the Chaoyang Basin may be confirmed as the Shangheshou Bed of the second member and the Dongpochi Bed of the third member; those in the Dapingfang-Meileyingzi Basin are as the Lamagou Bed of the second member, the Huanghuagou Bed of the lower third member and the Yuanjiawa Bed of the upper third member; and those in the Fuxin-Yixian Basin are listed as the Tuanshanzi Bed of the second member and the Pijiagou Bed of the third member. Since these basins are distinctly separated and the bird and reptile fossils are mostly new genera and species, we have to use the associated fossil ostracod assemblages as index to correlate the Xidagou Bed with the Shangheshou Bed and the Lamagou Bed, and to correlate the Yuanjiawa Bed with the Yangcaogoudonggou Bed and the Pijiagou Bed. Primarily, we established the sequence of the precious fossil-bearing beds of the Jiufotang Formation in western Liaoning. They are represented by, in ascending order, the Xidagou Bed of the second member, the Huanghuagou Bed of the lower third member, and the Yuanjiawa Bed of the upper third member. Obviously, this work has significance for the study on the time-space distribution and radiation of birds and dinosaurs during the period of the middle Early Cretaceous.展开更多
LA-ICPMS Zircon U-Pb dating is applied to volcanic rocks overlying and underlying the Salamander-bearing bed in the Daohugou beds of Ningcheng in Inner Mongola and Reshuichang of Lingyuan and Mazhangzi of Jianping in ...LA-ICPMS Zircon U-Pb dating is applied to volcanic rocks overlying and underlying the Salamander-bearing bed in the Daohugou beds of Ningcheng in Inner Mongola and Reshuichang of Lingyuan and Mazhangzi of Jianping in western Liaoning. The results indicate that the youngest age of the rocks in Daohugou of Ningcheng is 158 Ma, and the oldest one is 164 Ma. Synthesized researches indicate that the salamander-bearing beds in Daohugou of Ningcheng, Reshuichang of Lingyuan and Mazhangzi of Jianping were developed in the same period. The Daohugou beds were formed in the geological age of 164-158 Ma of the middle-late Jurassic. Whilst, the Daohugou beds and its corrdative strata should correspond to the Tiaojishan Formation （or Lanqi Formation） of the middle Jurassic in northern Hebei Province and western Liaoning Province, based on the disconformity between the Daohugou beds and its overlaying beds of the Tuchengzi Formation of Late Jurassic and the Jehol Beds of early Cretaceous, and the disconformity between the Daohugou Beds and its underlying Jiulongshan Formation, which is composed of conglomerate, sandstone, shale with coal and thin coal beds.展开更多
One of the new directions in the field of Cretaceous research is to elucidate the mechanism of the sedimentary transition from the Cretaceous black shales to oceanic red beds. A chemical sequential extraction method w...One of the new directions in the field of Cretaceous research is to elucidate the mechanism of the sedimentary transition from the Cretaceous black shales to oceanic red beds. A chemical sequential extraction method was applied to these two types of rocks from southern Tibet to investigate the burial records of reactive iron. Results indicate that carbonate-associated iron and pyrite are relatively enriched in the black shales, but depleted or absent in red beds. The main feature of the reactive iron in the red beds is relative enrichment of iron oxides （largely hematite）, which occurred during syn-depostion or early diagenesis. The ratio between iron oxides and the total iron indicates an oxygen-enriched environment for red bed deposition. A comparison between the reactive iron burial records and proxies of paleo-productivity suggests that paleo-productivity decreases when the ratio between iron oxides and the total iron increases in the red beds. This phenomenon could imply that the relationship between marine redox and productivity might be one of the reasons for the sedimentary transition from Cretaceous black shale to oceanic red bed deposition.展开更多
Red beds cover approximately 9.5%of China,and are home to approximately 144 million people.In total,83%of these lands are distributed in humid regions making it an important part of research on red bed soil erosion in...Red beds cover approximately 9.5%of China,and are home to approximately 144 million people.In total,83%of these lands are distributed in humid regions making it an important part of research on red bed soil erosion in China in these areas.This paper presents the main types of land degradation in red bed landscapes and the status of current soil erosion in a typical red bed basin,the Nanxiong Basin located in the north of Guangdong Province,China,and establishes the connection between management strategies and regional economic development in humid red bed regions of China.The soil erosive modulus was calculated in the Nanxiong Basin by using RUSLE(The Revised Universal Soil Loss Equation).The results of overlapping analyses demonstrated that appropriate measures,such as the Return Farmland to Forests initiative,should be taken at the junction of central red bed areas and mountainous areas in order to mitigate current soil erosion.Two examples are presented to demonstrate this:the tourism development in Mt.Danxiashan,a noted scenic mountainous area near Nanxiong Basin,and the land degradation mitigation in the Nanxiong Basin.Both examples promote local economic growth while simultaneously protecting the environment.A‘stakeholder'strategy is pursued at Mt.Danxiashan,which can help residents to understand their positive effects on the environment as well as increase their income.The second example,in Nanxiong City,showcases how local farmers became stakeholders by implementing contract responsibility and self-support systems for economic forests and terraced land in the 1980s.展开更多
In recent years, great progress has been made constantly in oil and gas exploration in the Lungudong region of the Tarim Basin. However, progress has been slow in the evaluation of its main oil-producing horizons -- t...In recent years, great progress has been made constantly in oil and gas exploration in the Lungudong region of the Tarim Basin. However, progress has been slow in the evaluation of its main oil-producing horizons -- the Ordovician carbonate reservoir beds. Based on previous researches and on the various data such as drilling, geology and oil test, in combination with the interpretation of each single-well imaging and conventional logging data, and through analysis and comparison, the identification methods in imaging and conventional logging for four types of carbonate reservoir beds in this region are summarized in this paper. Calculation formulas for four reservoir bed parameters, i. e. shale content, porosity, permeability and oil saturation in this region are proposed; and reservoir beds in this region are divided into three levels （Ⅰ, Ⅱ and Ⅲ） by combining oil test data and logging data, The lower limits of the effective porosity of reservoir beds and the fracture porosity of effective reservoir beds are determined as 1.8% and 0.04%, respectively. The physical property parameters are calculated by conventional logging curves, and the most advantageous areas for reservoir development are predicted comprehensively. On the plane, the high-value zones of reservoir bed parameters are mainly concentrated in the N-S-trending strike-slip fault, the Sangtamu fault horst zone and near the LG38 well area; vertically, the reservoir bed parameters of the Yijianfang Formation are better than those of the Yingshan and Lianglitage formations.展开更多
The no-till seeders of various soil opener configurations have been shown to produce various soil physical responses in relation to soil and climate conditions, thus affecting crop performance in permanent raised beds...The no-till seeders of various soil opener configurations have been shown to produce various soil physical responses in relation to soil and climate conditions, thus affecting crop performance in permanent raised beds （PRB） systems. This is particularly important in arid Northwest China where large volumes of residue are retained on the soil surface after harvest. In Zhangye, Gansu Province, China, a field trial assessed the effects of three typical （powered-chopper, powered-cutter and powered-disc） PRB no-till seeders and one traditional seeder on soil disturbance, residue cover index, bulk density, fuel consumption, plant growth, and subsequent yield. In general, seedbed conditions and crop performance for PRB no- till seeders seeded plots were better than for traditional seeded plots. In PRB cropping system, the powered-chopper seeder decreased mean soil disturbance and increased residue cover index compared to powered-disc and -cutter seeders. However, the results indicated that soil bulk density was 2.3-4.8% higher, soil temperature was 0.2-0.6℃ lower, and spring wheat emergence was 3.2-4.7% less. This was attributed to greater levels of residue cover and firmer seedbeds. Spring maize and wheat performance in the powered-cutter and -disc treatments was better （non-significant） than powered- chopper treatment. So powered disc no-till seeder, which generally provided the best planting condition and the highest yield, appeared to be the suitable seeder in heavy residue cover conditions. Considering the precision requirements for soil disturbance and residue cover, the powered strip-chopping no-till seeder could be a suitable option for PRB cropping system in Northwest China. Although these results are preliminary, they are still valuable for the design and selection of no-till seeders for PRB cropping systems in arid Northwest China.展开更多
基金Sponsored by Key Project of Hangzhou Science and Technology Bureau(20191203B78).
文摘The West Lake area and water system in West Lake scenic area of Hangzhou City directly affect the soil properties of waterfront lawn beds,which in turn have a significant impact on the growth of waterfront lawns.In order to further improve the quality of lawns,the conditions of 10 waterfront lawn beds in West Lake scenic area were tested and analyzed.The results showed that the waterfront lawn beds in West Lake scenic area were prone to salinization,with moderate or high pH values,moderate overall organic matter content,relatively sufficient nitrogen and phosphorus elements,and relatively deficient potassium elements.The contents of exchangeable calcium in all samples were higher than the lower limit,and the contents of exchangeable sodium,exchangeable magnesium,and available manganese in the soil were moderate or low,while the contents of available copper were moderate or high.
基金supported by the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2022QNLM 050302-4)the Geological Survey Project of the China Geological Survey(No.DD20230071)+1 种基金the China Geological Survey Project‘Investigation and Monitoring of the Coastal Geological Environment of the Yangtze River Estuary’(No.DD20242714)the cooperation fund of Collaborative Research on Marine Geological Environment and Hazards in the Yangtze River Delta and Red River Delta.
文摘Seagrass beds are crucial coastal ecosystems,functioning as vital blue carbon sinks and natural ecological barriers.However,these ecosystems are increasingly threatened by global climate events,coastal development,and water eutrophication,making them some of the most endangered ecosystems worldwide.In the Yellow Sea and Bohai Sea regions,seagrass bed assessment and monitoring have been largely overlooked.Thus,strengthening research efforts is necessary to identify current distribution patterns and long-term changes in seagrass bed resources.This study focused on a seagrass bed in Sanggou Bay,Rongcheng,using remote sensing(RS)and geographic information system technologies to analyze multisource satellite data from the US Landsat and Chinese resource satellite series.By combining RS indexes with historical survey data,large-scale temporal and geographic distribution data for seagrass beds were obtained in the study area from 1985 to 2022.The spatial distribution and evolution trends of the seagrass bed were analyzed using a water depth inversion model,and the factors driving its degradation were identified.Results indicated that the seagrass bed area in Sanggou Bay fluctuated between 100 and 140 km^(2) from 1985 to 2010.During 2010–2013,dynamic changes in the seagrass bed area increased,with a considerable decrease in its overall size.After 2014,changes were minimal,indicating a notably stable state.Seagrass bed degradation in Sanggou Bay is influenced by high-intensity human activities,pollution from coastal land sources,raft cultures,underwater terrain conditions,and sedimentary environmental factors.The findings offer essential insights for developing seagrass restoration and protection strategies in Sanggou Bay and contribute to the broader scientific efforts for coastal ecosystem conservation and rehabilitation.
基金supported by the National Key R&D Program of China(No.2021YFF0502100)the National Natural Science Foundation of China(Nos.52278461 and 52308467).
文摘Cracking of early-age concrete can occur in the track beds of high-speed railways due to changes in material properties,environmental effects,and construction processes.This is a multi-field,time-varying issue involving hydro-thermo-chemo-mechanical coupling.However,to date,research has not adequately described the early-age cracking mechanisms in track beds,and few risk control measures have been proposed.To solve this problem,we incorporated the hydration degree of concrete into multi-field coupling equations for early-age concrete,and set boundary conditions that account for environmental influences and various stress factors that typically cause early creep of concrete.A four-field coupled risk prediction model was built based on hydro-thermo-chemo-mechanical properties,and was used to calculate and analyze various time-varying behavior(including the risk and form of cracking)in the hydro,thermo,chemo,and mechanical fields of early-age concrete.Finally,we focused on material-related factors(maximum heat of hydration and peak heat release time),environmental factors(temperature difference between day and night,average daily cooling rate,and intensity of solar radiation),and construction technique factors(molding temperature,pouring time,and thermal insulation coefficient).The influence of these factors on the early-age cracking risk of the track bed was analyzed,and risk control measures against early cracking were proposed accordingly.
基金EES acknowledges funding from a NERC Frontiers grant(NE/V010824/1)Leverhulme Trust research grant(RPG-2022-313).
文摘Over the past two decades,it has become increasingly apparent that early Mars may once have been warmer,wetter and more habitable for microbial life than it is today,which has spurred discussions about potential biosignatures that may be preserved in Martian sediments.An impediment to this line of research is the pervasive oxidation of Mars’surface due to photochemical oxidants that have likely destroyed remnants of organic matter.Here,we investigate whether nitrogen(N)transferred from biomass to phyllosilicate minerals during diagenesis can be preserved in oxidized mudrocks.We investigate two sequences of terrestrial Proterozoic red beds,namely the Sibley Group(1.4 Ga)in Canada and the Stoer Group(1.2 Ga)in Scotland,and we find enrichments in authigenic N in the range of several tens of ppm in both units.The highest concentrations(ca.100 ppm on average)are found in the most desiccated red beds of the Stoer Group,concurrent with enrichments in potassium(K).We discuss similarities and differences between the two sets of rocks with regards to salinity,pH,biological productivity and K-metasomatism,and we conclude that the ideal mechanism for the preservation of biogenic N in red beds may be in-situ release of ammonium from microbial mats into the clay substrate,possibly facilitated by early diagenetic,biologically induced illitization.Illite and smectite have been observed on Mars,and experiments suggest that Martian waters contained moderate amounts of dissolved K.Hence,it is conceivable that a similar K and N enrichment process could have occurred as to what we document for the Proterozoic,preserving evidence of life that may have survived to the modern day.
基金financial support of the National Natural Science Foundation of China(22178265)Tianjin Science and Technology Project(21JCYBJC00400)Open Project for Ningbo Key Laboratory of Green Petrochemical Carbon Emission Reduction Technology and Equipment(ZITJU2023-ZYDK001).
文摘This work synthesized a series of Ni/CeO_(2)/Al_(2)O_(3) catalysts with varying CeO_(2) doping amounts to enhance low-temperature CO_(2) methanation.The introduction of CeO_(2) weakens the interaction between Ni and Al_(2)O_(3),leading to the formation of Ni-CeO_(2) active sites.This results in a high dispersion of Ni and CeO_(2),improved catalyst reducibility,increased number of active sites,and enhanced the CO_(2) methanation.This work further investigated the impact of WHSV and catalyst stacking configuration to enhance the reaction.When the catalyst is stacked into three segments with a temperature gradient of 330℃,300℃,and 250℃under WHSV=9000 ml·h^(-1)·g^(-1),the CO_(2) conversion significantly increases to 95%,which is remarkably close to the thermodynamic equilibrium(96%).
文摘This work investigates the influence of the type sludge on drainage, plant development, purification performances and biosolids quality. Drainage properties were measured through the frequency of clogging, the percentage of leachate recovered and the dryness of accumulated sludge. Plant development was measured through the density, the height and the stem diameter. Purification performance was evaluated from the reduction rate. Biosolids quality was measured after 3 months of maturation. The results show that the clogging frequencies were 9.5%;0% and 3.7%;the volume of leachate recovered was 42.2%;20.4% and 24.7% and, the dryness was 33.4%;61.1% and 52.4% for FS-ST, FS-STT and SS respectively. Plants densities were about, with densities 197.1, 171.3 and 178.3 plants/m2 in beds fed respectively with FS-ST, FS-STT and SS. Despite the high removal rates, the concentrations of pollutants in the leachates are above the Senegalese standard NS 05-061 for discharge into the environment. The biosolids are all mature with C/N and NH4+/NO3?ratios lower than 12 and 1 respectively. The biosolids are also rich in organic and mineral elements. The concentrations of Ascaris eggs are higher than the WHO recommendations. These biosolids should be stored for additional time or composted.
基金support from the National Natural Science Foundation of China (Nos.52301324 and 52001276)the Natural Science Foundation of Zhejiang Province (No.LQ24E090001)+2 种基金the Open Fund of Key Laboratory of Estuary and Coast of Zhejiang Province (No.ZIHE21005)the Natural Science Foundation of Ningbo (No.2021J096)the Zhejiang Transportation Science and Technology (No.2021064)。
文摘Elucidating the flow features around piles in local scouring processes is crucial for studies of local scouring mechanisms and scour depth estimates.This study details the flow turbulence characteristics of two submerged piles that are determined by solving the Navier-Stokes equations with the improved delayed detached eddy simulation model.This model is verified by comparing experimental and numerical results for hydrodynamic parameters with the literature for both square-crossing piles(SCPs)and circular-crossing piles(CCPs).Original topographies of flat and scoured beds(i.e.,the initial and equilibrium scouring stages)are based on experimental results obtained by the authors in the present paper.SCP and CCP flow features in the scouring process are discussed.The results indicate that during the scouring process,the time-averaged drag coefficient and root mean square(rms)of the lift coefficient increase linearly in the CCP test,while the rms of the lift coefficient in the SCP test decreases linearly.Moreover,the minimum pressure coefficient is always located in the upstream corners in the SCP case but moves from 72.5°to 79.5°when the scour hole is completely developed in the CCP case.Downward flow behind the pile,which is generated by separated boundary layers above the top face of the pile,can reach the sand bed and turn the separated shear layers into patches of small vortices in the near-wake regions.Thus,the high shear stress zones are mainly at the scour edges under scoured-bed conditions.
基金supported by the National Natural Science Foundation of China(52336003,52206096,52176076)the Special Expert Project of Shandong Province Taishan Scholars Program(ts20190937).
文摘As a high-performance material with great application potential,the application of carbon nanotubes has been limited by their production volume.A distributor-less conical fluidized bed is the main equipment used in the industrial production of carbon nanotubes.To improve the production volume and product quality of carbon nanotubes,the study of fluidized-bed-diameter scaling is important.Three different diameters of distributor-less conical fluidized beds were established,and then the particle behavior and bubble characteristics of carbon nanotube clusters at these bed diameters were investigated.Time-series and wavelet analysis methods were used to analyze the pressure-fluctuation signals inside the fluidized beds.Results showed that the distributor-less design caused the airflow to break through the middle of the bed,which did not change with the change in bed diameter.The powder-bridging phenomenon of carbon nanotube clusters in a 100-mm-diameter fluidized bed was related to the special microstructure of carbon nanotube clusters.The frequency of pressure fluctuations in the bed decreased nonlinearly with increasing bed diameter.This study can guide the design and scale-up of distributor-less conical fluidized beds,especially for the scale-up of carbon nanotube production equipment,which can contribute to the improvement of carbon nanotubes’capacity and quality in industrial production.
基金financial support from the National Natural Science Foundation of China(21991104).
文摘The understanding of the gas-liquid flow characteristics in a micro-packed bed reactor is still immature,especially for many gas-organic working systems commonly used in industry.Accordingly,this study proposes a platform to investigate the gas-eliquid flow characteristics in a micro-packed bed reactor and presents a unified expression for these characteristics of both organic and aqueous liquid phase.The influence of two-phase flow rate,working solution viscosity,and packing particle size on the liquid holdup and pressure drop were studied.The gas-organic working systems results show that the liquid holdup ranges between 0.5 and 0.8 and pressure drop ranges from 50 to 350 kPa·m^(-1).In particular,a strong correlation between the two flow characteristics parameters(liquid holdup and pressure drop)was proposed for the first time.Finally,a general pressure drop mathematical prediction model in micropacked bed were developed.
基金The work has been supported by a grant received from the Ministry of Education,Government of India under the Scheme for the Promotion of Academic and Research Collaboration(SPARC)(ID:SPARC/2019/1396).
文摘We have proposed a new mathematical method,the SEIHCRD model,which has an excellent potential to predict the incidence of COVID-19 diseases.Our proposed SEIHCRD model is an extension of the SEIR model.Three-compartments have added death,hospitalized,and critical,which improves the basic understanding of disease spread and results.We have studiedCOVID-19 cases of six countries,where the impact of this disease in the highest are Brazil,India,Italy,Spain,the United Kingdom,and the United States.After estimating model parameters based on available clinical data,the modelwill propagate and forecast dynamic evolution.Themodel calculates the Basic reproduction number over time using logistic regression and the Case fatality rate based on the selected countries’age-category scenario.Themodel calculates two types of Case fatality rate one is CFR daily,and the other is total CFR.The proposed model estimates the approximate time when the disease is at its peak and the approximate time when death cases rarely occur and calculate how much hospital beds and ICU beds will be needed in the peak days of infection.The SEIHCRD model outperforms the classic ARXmodel and the ARIMA model.RMSE,MAPE,andRsquaredmatrices are used to evaluate results and are graphically represented using Taylor and Target diagrams.The result shows RMSE has improved by 56%–74%,and MAPE has a 53%–89%improvement in prediction accuracy.
基金Projects(50934002,51074013,51304076,51104100)supported by the National Natural Science Foundation of ChinaProject(IRT0950)supported by the Program for Changjiang Scholars Innovative Research Team in Universities,ChinaProject(2012M510007)supported by China Postdoctoral Science Foundation
文摘Methods and procedures of three-dimensional （3D） characterization of the pore structure features in the packed ore particle bed are focused. X-ray computed tomography was applied to deriving the cross-sectional images of specimens with single particle size of 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10 ram. Based on the in-house developed 3D image analysis programs using Matlab, the volume porosity, pore size distribution and degree of connectivity were calculated and analyzed in detail. The results indicate that the volume porosity, the mean diameter of pores and the effective pore size （d50） increase with the increasing of particle size. Lognormal distribution or Gauss distribution is mostly suitable to model the pore size distribution. The degree of connectivity investigated on the basis of cluster-labeling algorithm also increases with increasing the particle size approximately.
基金The research was supported by the National Natural Science Foundation of China （grant #40272006, 30430100, 30370184）RFDP of the Chinese Ministry of Education, and RCQJ Project of Beijing Municipal Commission of Education. Thanks are given to Prof. R. C. Fox （University of Alberta） for reading and improving the manuscript.
文摘Lacustrine deposits exposed at Daohugou, Inner Mongolia, China, have yielded superbly preserved vertebrate fossils. The fossil beds were first misinterpreted as of Early Cretaceous age, based on alleged occurrences of key fossils of the Jehol Biota. Compelling evidence revealed by more rigorous research involving regional biostratigraphy, radiometric dating, and paleontology supports the Middle Jurassic age of the fossil beds. Despite the awesome evidence for the Middle Jurassic age of the Daohugou beds, the age dispute has been resurrected recently by invoking an overturned stratigraphic sequence. A careful review of the data, however, found no evidence that this sequence has been overturned. In addition, many of the assumptions, on which the conjecture of the fossil beds being post- Middle Jurassic is imprudently based, are self-contradictory or otherwise misleading. Thus, the post- Middle Jurassic age of the Daohugou beds as an unfounded conclusion can readily be dismissed.
基金supported by the National Basic Research Program of China(973 ProgramGrant No 2006CB701400)the Excellent Teacher study Program(Grant No53200959212)
文摘The planktic foraminifera of the Chuangde Formation （Upper Cretaceous Oceanic Red Beds, CORBs） as exposed at Tianbadong section, Kangmar, southern Tibet has been firstly studied for a detailed for a detailed biostratigraphy elaboration. A rich and well-preserved planktic foraminifera were recovered from the Chuangde Formation of the Tianbadong section and the Globotruncanita elevata, Globotruncana ventricosa, Radotruncana calcarata, Globotruncanella havanensis, Globotruncana aegyptiaca, Gansserina gansseri and Abathomphalus mayaroensis zones have been recognized. The planktic foraminiferal assemblage points to an early Campanian to Maastrichitian age for the CORBs of the eastern North Tethyan Himalayan sub-belt, which also provides a better understanding of the shifting progress of the Indian Plate to the north and the evolution of the Neotethyan ocean. The lithostratigraphy of the Chuangde Formation of the Tianbadong section comprises two lithological sequences observed in ascending succession： a lower unit （the Shale Member） mainly composed of purple （cherry-red, violet-red） shales with interbedded siltstones and siliceous rocks; and an upper unit （the Limestone Member） of variegated limestones. The strata of the Chuangde Formation in the Tianbadong section are similar to CORBs in other parts of the northern Tethyan Himalaya area of Asia （Gyangze, Sa＇gya, Sangdanlin, northern Zanskar, etc.）. The fossil contents of the Chuangde Formation in the sections （CORBs） studied provide a means of correlation with the zonation schemes for those of the northern Tethyan Himalayan sub-belt and the Upper Cretaceous of the southern Tethyan Himalayan sub-belt. Paleogeographic reconstruction for the Late Cretaceous indicates that the Upper Cretaceous Chuangde Formation （CORBs） and correlatable strata in northern Zanskar were representative of slope to basinal deposits, which were situated in the northern Tethyan Belt. Correlatable Cretaceous strata in Spiti and Gamba situated in the southern Tethyan Belt in contrast were deposited in shelf environments along the Tethyan Himalayan passive margin. CORBs are most likely formed by the oxidation of Fe（II）-enriched, anoxic deep ocean water near the chemocline that separated the oxic oceanic surface from the anoxic.
文摘Based on the subdivision into three members of the Lower Cretaceous Jiufotang Formation in western Liaoning, this paper deals mainly with the division and correlation of precious fossil birdand reptile-bearing beds of the formation in the Dachengzi, Chaoyang, Dapingfang.Meileyingzi and Fuxin-Yixian basins. Among them, the precious fossil-bearing beds in the Dachengzi Basin may be recognized as the Xidagou Bed of the second member and the Yangcaogoudonggou Bed of the third member; those in the Chaoyang Basin may be confirmed as the Shangheshou Bed of the second member and the Dongpochi Bed of the third member; those in the Dapingfang-Meileyingzi Basin are as the Lamagou Bed of the second member, the Huanghuagou Bed of the lower third member and the Yuanjiawa Bed of the upper third member; and those in the Fuxin-Yixian Basin are listed as the Tuanshanzi Bed of the second member and the Pijiagou Bed of the third member. Since these basins are distinctly separated and the bird and reptile fossils are mostly new genera and species, we have to use the associated fossil ostracod assemblages as index to correlate the Xidagou Bed with the Shangheshou Bed and the Lamagou Bed, and to correlate the Yuanjiawa Bed with the Yangcaogoudonggou Bed and the Pijiagou Bed. Primarily, we established the sequence of the precious fossil-bearing beds of the Jiufotang Formation in western Liaoning. They are represented by, in ascending order, the Xidagou Bed of the second member, the Huanghuagou Bed of the lower third member, and the Yuanjiawa Bed of the upper third member. Obviously, this work has significance for the study on the time-space distribution and radiation of birds and dinosaurs during the period of the middle Early Cretaceous.
文摘LA-ICPMS Zircon U-Pb dating is applied to volcanic rocks overlying and underlying the Salamander-bearing bed in the Daohugou beds of Ningcheng in Inner Mongola and Reshuichang of Lingyuan and Mazhangzi of Jianping in western Liaoning. The results indicate that the youngest age of the rocks in Daohugou of Ningcheng is 158 Ma, and the oldest one is 164 Ma. Synthesized researches indicate that the salamander-bearing beds in Daohugou of Ningcheng, Reshuichang of Lingyuan and Mazhangzi of Jianping were developed in the same period. The Daohugou beds were formed in the geological age of 164-158 Ma of the middle-late Jurassic. Whilst, the Daohugou beds and its corrdative strata should correspond to the Tiaojishan Formation （or Lanqi Formation） of the middle Jurassic in northern Hebei Province and western Liaoning Province, based on the disconformity between the Daohugou beds and its overlaying beds of the Tuchengzi Formation of Late Jurassic and the Jehol Beds of early Cretaceous, and the disconformity between the Daohugou Beds and its underlying Jiulongshan Formation, which is composed of conglomerate, sandstone, shale with coal and thin coal beds.
基金This work is supported by the National Key Basic Research Program （2006CB701406）；Natural Science Foundation of China for Youth （40403003） ；Key Project of the Natural Science Foundation of China （40332020）, and is a contribution to IGCP 463.
文摘One of the new directions in the field of Cretaceous research is to elucidate the mechanism of the sedimentary transition from the Cretaceous black shales to oceanic red beds. A chemical sequential extraction method was applied to these two types of rocks from southern Tibet to investigate the burial records of reactive iron. Results indicate that carbonate-associated iron and pyrite are relatively enriched in the black shales, but depleted or absent in red beds. The main feature of the reactive iron in the red beds is relative enrichment of iron oxides （largely hematite）, which occurred during syn-depostion or early diagenesis. The ratio between iron oxides and the total iron indicates an oxygen-enriched environment for red bed deposition. A comparison between the reactive iron burial records and proxies of paleo-productivity suggests that paleo-productivity decreases when the ratio between iron oxides and the total iron increases in the red beds. This phenomenon could imply that the relationship between marine redox and productivity might be one of the reasons for the sedimentary transition from Cretaceous black shale to oceanic red bed deposition.
基金supported by the National Natural Science Foundation of China(41901005)the Fundamental Research Funds for the Central Universities(SWU 118202)supported by the Ministry of Education,Science and Technological Development of the Republic of Serbia(Projects 172001 and 176006)
文摘Red beds cover approximately 9.5%of China,and are home to approximately 144 million people.In total,83%of these lands are distributed in humid regions making it an important part of research on red bed soil erosion in China in these areas.This paper presents the main types of land degradation in red bed landscapes and the status of current soil erosion in a typical red bed basin,the Nanxiong Basin located in the north of Guangdong Province,China,and establishes the connection between management strategies and regional economic development in humid red bed regions of China.The soil erosive modulus was calculated in the Nanxiong Basin by using RUSLE(The Revised Universal Soil Loss Equation).The results of overlapping analyses demonstrated that appropriate measures,such as the Return Farmland to Forests initiative,should be taken at the junction of central red bed areas and mountainous areas in order to mitigate current soil erosion.Two examples are presented to demonstrate this:the tourism development in Mt.Danxiashan,a noted scenic mountainous area near Nanxiong Basin,and the land degradation mitigation in the Nanxiong Basin.Both examples promote local economic growth while simultaneously protecting the environment.A‘stakeholder'strategy is pursued at Mt.Danxiashan,which can help residents to understand their positive effects on the environment as well as increase their income.The second example,in Nanxiong City,showcases how local farmers became stakeholders by implementing contract responsibility and self-support systems for economic forests and terraced land in the 1980s.
基金supported by the State Key Development Program for Basic Research of China(Grant No.2006CB202308)
文摘In recent years, great progress has been made constantly in oil and gas exploration in the Lungudong region of the Tarim Basin. However, progress has been slow in the evaluation of its main oil-producing horizons -- the Ordovician carbonate reservoir beds. Based on previous researches and on the various data such as drilling, geology and oil test, in combination with the interpretation of each single-well imaging and conventional logging data, and through analysis and comparison, the identification methods in imaging and conventional logging for four types of carbonate reservoir beds in this region are summarized in this paper. Calculation formulas for four reservoir bed parameters, i. e. shale content, porosity, permeability and oil saturation in this region are proposed; and reservoir beds in this region are divided into three levels （Ⅰ, Ⅱ and Ⅲ） by combining oil test data and logging data, The lower limits of the effective porosity of reservoir beds and the fracture porosity of effective reservoir beds are determined as 1.8% and 0.04%, respectively. The physical property parameters are calculated by conventional logging curves, and the most advantageous areas for reservoir development are predicted comprehensively. On the plane, the high-value zones of reservoir bed parameters are mainly concentrated in the N-S-trending strike-slip fault, the Sangtamu fault horst zone and near the LG38 well area; vertically, the reservoir bed parameters of the Yijianfang Formation are better than those of the Yingshan and Lianglitage formations.
基金financed by the National Natural Science Foundation of China (51175499)the Beijing Natural Science Foundation, China (6112015)the Australian Centre for International Agricultural Research (ACIAR)
文摘The no-till seeders of various soil opener configurations have been shown to produce various soil physical responses in relation to soil and climate conditions, thus affecting crop performance in permanent raised beds （PRB） systems. This is particularly important in arid Northwest China where large volumes of residue are retained on the soil surface after harvest. In Zhangye, Gansu Province, China, a field trial assessed the effects of three typical （powered-chopper, powered-cutter and powered-disc） PRB no-till seeders and one traditional seeder on soil disturbance, residue cover index, bulk density, fuel consumption, plant growth, and subsequent yield. In general, seedbed conditions and crop performance for PRB no- till seeders seeded plots were better than for traditional seeded plots. In PRB cropping system, the powered-chopper seeder decreased mean soil disturbance and increased residue cover index compared to powered-disc and -cutter seeders. However, the results indicated that soil bulk density was 2.3-4.8% higher, soil temperature was 0.2-0.6℃ lower, and spring wheat emergence was 3.2-4.7% less. This was attributed to greater levels of residue cover and firmer seedbeds. Spring maize and wheat performance in the powered-cutter and -disc treatments was better （non-significant） than powered- chopper treatment. So powered disc no-till seeder, which generally provided the best planting condition and the highest yield, appeared to be the suitable seeder in heavy residue cover conditions. Considering the precision requirements for soil disturbance and residue cover, the powered strip-chopping no-till seeder could be a suitable option for PRB cropping system in Northwest China. Although these results are preliminary, they are still valuable for the design and selection of no-till seeders for PRB cropping systems in arid Northwest China.
