The object of research of this paper is the DSA380 high-speed pantograph.The near-field unsteady flow around the pantograph was investigated using large eddy simulation(LES)while the far-field aerodynamic noise was an...The object of research of this paper is the DSA380 high-speed pantograph.The near-field unsteady flow around the pantograph was investigated using large eddy simulation(LES)while the far-field aerodynamic noise was analysed in the frame of the Ffowcs Williams-Hawkings(FW-H)acoustic analogy.According to the results,the contact strip,base frame and knuckle are the main aerodynamic noise sources,with vortex shedding,flow separation and recombination around the pantograph being related key physical factors.The aerodynamic noise radiates outwards in the form of spherical waves when the distance of the noise receiving point is farther than 8 m.The sound pressure level(SPL)grows approximately as the 6th power of pantograph operating speed.The aerodynamic noise energy is mainly concentrated in the region of 400-1000 Hz,and the frequency band is wider with crosswind than without crosswind.The peak frequency displays a linear relationships with the operating speed and crosswind velocity,respectively.The aerodynamic and aeroacoustic generation from the knuckle-downstream orientation of the pantograph is superior to those of the knuckle-upstream orientation model.This finding may be used for the optimal design of future pantograph configurations in the presence of crosswind.展开更多
The thermal decomposition process was studied by the TG–DTA analyzer. The results show that the decomposition process of sodium hydroxyethyl sulfonate consisted of three stages: the mass loss for the first, the secon...The thermal decomposition process was studied by the TG–DTA analyzer. The results show that the decomposition process of sodium hydroxyethyl sulfonate consisted of three stages: the mass loss for the first, the second and third stages may be about the groups of CH_3CH_2OH, CH_3CHO and SO_2 volatilized, respectively. The decomposition residuum of three stages was analyzed by FT-IR, and the results of FT-IR agreed with the decomposition process predicted by theoretical weight loss. The specific heat capacity of sodium hydroxyethyl sulfonate was determined by differential scanning calorimetry(DSC). The melting temperature and melting enthalpy were obtained to be 465.41 K and 25.69 kJ·mol^(-1), respectively. The molar specific heat capacity of sodium hydroxyethyl sulfonate was determinated from 310.15 K to 365.15 K and expressed as a function of temperature.展开更多
The liquid phase oxidation of cyclohexylbenzene(CHB)is a new green synthetic approach to cyclohexylbenzene-1-hydroperoxide(CHBHP),a key intermediate for preparing phenol and cyclohexanone.In this work,aryl-substituted...The liquid phase oxidation of cyclohexylbenzene(CHB)is a new green synthetic approach to cyclohexylbenzene-1-hydroperoxide(CHBHP),a key intermediate for preparing phenol and cyclohexanone.In this work,aryl-substituted(Cl and Br)derivatives of N-hydroxyphthalimide(NHPI)were synthesized and their catalytic performances for CHB oxidation were studied.In addition,geometric optimization and transition state search were performed using DFT calculations.Both experimental and theoretical studies have proven that chloro-substitution on NHPI can significantly improve its catalytic effects on the oxidation of CHB by oxygen.Compared with NHPI,CHB conversion and selectivity of CHBHP over Cl;NHPI were increased by 10.47%and 13.24%.The strategy of aryl-substituting NHPI with halogen atoms proposed in this study would provide a potential way to the development of new NHPI-based catalysts for aerobic oxidation reactions.展开更多
An excellent cardinality estimation can make the query optimiser produce a good execution plan.Although there are some studies on cardinality estimation,the prediction results of existing cardinality estimators are in...An excellent cardinality estimation can make the query optimiser produce a good execution plan.Although there are some studies on cardinality estimation,the prediction results of existing cardinality estimators are inaccurate and the query efficiency cannot be guaranteed as well.In particular,they are difficult to accurately obtain the complex relationships between multiple tables in complex database systems.When dealing with complex queries,the existing cardinality estimators cannot achieve good results.In this study,a novel cardinality estimator is proposed.It uses the core techniques with the BiLSTM network structure and adds the attention mechanism.First,the columns involved in the query statements in the training set are sampled and compressed into bitmaps.Then,the Word2vec model is used to embed the word vectors about the query statements.Finally,the BiLSTM network and attention mechanism are employed to deal with word vectors.The proposed model takes into consideration not only the correlation between tables but also the processing of complex predicates.Extensive experiments and the evaluation of BiLSTM-Attention Cardinality Estimator(BACE)on the IMDB datasets are conducted.The results show that the deep learning model can significantly improve the quality of cardinality estimation,which is a vital role in query optimisation for complex databases.展开更多
Since defects such as traps and oxygen vacancies exist in dielectrics,it is difficult to fabricate a high-performance MoS_(2)field-effect transistor(FET)using atomic layer deposition(ALD)Al_(2)O_(3)as the gate dielect...Since defects such as traps and oxygen vacancies exist in dielectrics,it is difficult to fabricate a high-performance MoS_(2)field-effect transistor(FET)using atomic layer deposition(ALD)Al_(2)O_(3)as the gate dielectric layer.In this paper,NH_(3)in situ doping,a process treatment approach during ALD growth of Al_(2)O_(3),is used to decrease these defects for better device characteristics.MoS_(2)FET has been well fabricated with this technique and the effect of different NH_(3)in situ doping sequences in the growth cycle has been investigated in detail.Compared with counterparts,those devices with NH_(3)in situ doping demonstrate obvious performance enhancements:Ion/Ioff is improved by one order of magnitude,from 1.33×10^(5)to 3.56×10^(6),the threshold voltage shifts from-0.74 V to-0.12 V and a small subthreshold swing of 105 m V/dec is achieved.The improved MoS_(2)FET performance is attributed to nitrogen doping by the introduction of NH_(3)during the Al_(2)O_(3)ALD growth process,which leads to a reduction in the surface roughness of the dielectric layer and the repair of oxygen vacancies in the Al_(2)O_(3)layer.Furthermore,the MoS_(2)FET processed by in situ NH_(3)doping after the Al and O precursor filling cycles demonstrates the best performance;this may be because the final NH_(3)doping after film growth restores more oxygen vacancies to screen more charge scattering in the MoS_(2)channel.The reported method provides a promising way to reduce charge scattering in carrier transport for high-performance MoS_(2)devices.展开更多
Based on H1-Galerkin mixed finite element method with nonconforming quasi-Wilson element, a numerical approximate scheme is established for pseudo-hyperbolic equations under arbitrary quadrilateral meshes. The corresp...Based on H1-Galerkin mixed finite element method with nonconforming quasi-Wilson element, a numerical approximate scheme is established for pseudo-hyperbolic equations under arbitrary quadrilateral meshes. The corresponding optimal order error estimate is derived by the interpolation technique instead of the generalized elliptic projection which is necessary for classical error estimates of finite element analysis.展开更多
The crystal phases are essential to the physicochemical properties and functionalities of materials.Copper selenide has emerged as an important and appealing semiconductor,which can exist in a variety of polymorphic p...The crystal phases are essential to the physicochemical properties and functionalities of materials.Copper selenide has emerged as an important and appealing semiconductor,which can exist in a variety of polymorphic phases.However,the richness of polymorphs also makes it a challenge to the direct preparation of copper selenide nanocrystals with tunable phases.Herein,two polymorphs,that is,quasitetragonal Cu2−xSe nanocubes and metastable wurtzite Cu2Se nanodisks,are successfully synthesized by using a single precursor,copper(I)selenocyanate(CuSeCN),as the Cu and Se sources.The key to phase modulation is the optimal choice of the ligand in the synthesis.The as‐prepared nanocrystals possess different morphologies and compositions,giving rise to distinct optical properties and electrical conductivities.Interestingly,the copper selenide nanocrystals can provide a platform for the rational construction of two types of amorphous hollow Au─Cu─Se nanostructures by reaction with Au(I)precursor,in which their final shapes are well kept as that of the original nanocrystal templates.This work provides an easy strategy for the phase‐controlled synthesis of copper selenide nanocrystals and enables the design of new materials for broad applications.展开更多
On January 22,2020,China National Center for Bioinformation(CNCB)released the 2019 Novel Coronavirus Resource(2019nCoVR),an open-access information resource for the severe acute respiratory syndrome coronavirus 2(SARS...On January 22,2020,China National Center for Bioinformation(CNCB)released the 2019 Novel Coronavirus Resource(2019nCoVR),an open-access information resource for the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).2019nCoVR features a comprehensive integration of sequence and clinical information for all publicly available SARS-CoV-2 isolates,which are manually curated with value-added annotations and quality evaluated by an automated in-house pipeline.Of particular note,2019nCoVR offers systematic analyses to generate a dynamic landscape of SARS-CoV-2 genomic variations at a global scale.It provides all identified variants and their detailed statistics for each virus isolate,and congregates the quality score,functional annotation,and population frequency for each variant.Spatiotemporal change for each variant can be visualized and historical viral haplotype network maps for the course of the outbreak are also generated based on all complete and high-quality genomes available.Moreover,2019nCoVR provides a full collection of SARS-CoV-2 relevant literature on the coronavirus disease 2019(COVID-19),including published papers from PubMed as well as preprints from services such as bioRxiv and medRxiv through Europe PMC.Furthermore,by linking with relevant databases in CNCB,2019nCoVR offers data submission services for raw sequence reads and assembled genomes,and data sharing with NCBI.Collectively,SARS-CoV-2 is updated daily to collect the latest information on genome sequences,variants,haplotypes,and literature for a timely reflection,making 2019nCoVR a valuable resource for the global research community.2019nCoVR is accessible at https://bigd.big.ac.cn/ncov/.展开更多
Pulsed gas-solid fluidized beds can effectively separate fine coal,and bubbles play an important role in creating suitable separation conditions.The present study performed statistical and image analyses of the evolut...Pulsed gas-solid fluidized beds can effectively separate fine coal,and bubbles play an important role in creating suitable separation conditions.The present study performed statistical and image analyses of the evolution of bubbles in a two-dimensional pulsed gas-solid fluidized bed using a high-speed dynamic camera.The effects of apparent gas velocity,pulsation frequency and particle size on bubble characteristics and bed expansi on were analyzed.The results indicate that,when a fluctuation freque ncy is added,the expa nsion height of the bed in creases,the effect of attachme nt to the bed wall decreases,the leading diameter and rising velocity of the bubbles both decrease and the degree of bubble deformation increases.These trends are also more obvious for fine particles.These findings dem on strate that a high density pulsed gas-solid fluidized bed can effectively combine gases and solids to produce a uniform,stable mixture.The bubble diameter and rising velocity were also simulated in the present work,and the relationship between the two was established using a fitting model with an error within 5%.This model provides an effective means of predicting bubble velocity as well as studying the distribution of the bubble phase and improving the stability of the bed density.展开更多
In recent years,government investments in implementing restrictive public policies on the treatment and discharge of effluents from the aquaculture industry have increased.Hence,efficient and cleaner methods for aquac...In recent years,government investments in implementing restrictive public policies on the treatment and discharge of effluents from the aquaculture industry have increased.Hence,efficient and cleaner methods for aquaculture production are needed.Recirculating aquaculture systems(RAS)offers water conservation by recycling the treated aquaculture water for reuse.RAS wastewater treatment using a moving bed bioreactors(MBBRs)process has been considered well suited for maintaining good water quality,thereby making fish farming more sustainable.Currently,improvements were achieved in tackling the influence of salinity,organic matter,disinfectant,and bioreactor start-up process on the MBBR performance efficiency.This review highlights an updated overview of recent development made using MBBR to treat the residual water from RAS.Precisely,nitrification and simultaneous nitrification-denitrification(SND),and other hybrid processes for nitrogen removal were elucidated.Finally,future challenges and prospects of MBBRs in RAS facilities that need to be considered were also proposed.展开更多
There is a need for synthetic grafts to reconstruct large bone defects using minimal invasive surgery.Our previous study showed that incorporation of Sr into bioactive borate glass cement enhanced the osteogenic capac...There is a need for synthetic grafts to reconstruct large bone defects using minimal invasive surgery.Our previous study showed that incorporation of Sr into bioactive borate glass cement enhanced the osteogenic capacity in vivo.However,the amount of Sr in the cement to provide an optimal combination of physicochemical properties and capacity to stimulate bone regeneration and the underlying molecular mechanism of this stimulation is yet to be determined.In this study,bone cements composed of bioactive borosilicate glass particles substituted with varying amounts of Sr(0 mol%to 12 mol%SrO)were created and evaluated in vitro and in vivo.The setting time of the cement increased with Sr substitution of the glass.Upon immersion in PBS,the cement degraded and converted more slowly to HA(hydroxyapatite)with increasing Sr substitution.The released Sr2+modulated the proliferation,differentiation,and mineralization of hBMSCs(human bone marrow mesenchymal stem cells)in vitro.Osteogenic characteristics were optimally enhanced with cement(designated BG6Sr)composed of particles substituted with 6mol%SrO.When implanted in rabbit femoral condyle defects,BG6Sr cement supported better peri-implant bone formation and bone-implant contact,comparing to cements substituted with 0mol%or 9mol%SrO.The underlying mechanism is involved in the activation of Wnt/β-catenin signaling pathway in osteogenic differentiation of hBMSCs.These results indicate that BG6Sr cement has a promising combination of physicochemical properties and biological performance for minimally invasive healing of bone defects.展开更多
A decay function for the layering effect during the projectile penetrating into layered targets is constructed, which is obtained via the theoretical solution of a dynamically expanding layered spherical cavity with f...A decay function for the layering effect during the projectile penetrating into layered targets is constructed, which is obtained via the theoretical solution of a dynamically expanding layered spherical cavity with finite radius in the layered targets that are assumed to be incompressible Mohr-Coulomb materials. By multiplying the decay function with the semi-empirical forcing functions that account for all the constitutive behavior of the targets, the forcing functions for the layered targets are obtained. Then, the forcing functions are used to represent the targets and are applied on the projectile surface as the pressure boundary condition where the projectile is modeled by an explicit transient dynamic finite element code. This methodology is implemented into ABAQUS explicit solver via the user subroutine VDLOAD, which eliminates the need for discretizing the targets and the need for the complex contact algorithm. In order to verify the proposed layering effect model, depth-of-penetration experiments of the 37 mm hard core projectile penetrating into three sets of fiber concrete and soil layered targets are conducted. The predicted depths of penetration show good agreement with the experimental data. Furthermore,the influence of layering effect on projectile trajectory during earth penetration is investigated. It is found that the layering effect should be taken into account if the final position and trajectory of the projectile are the main concern.展开更多
In this paper,the variation of bubble size and number in the separation process of vibrated fluidized bed as well as the influence of bubble movement on the axial distribution of fine coal in different positions of th...In this paper,the variation of bubble size and number in the separation process of vibrated fluidized bed as well as the influence of bubble movement on the axial distribution of fine coal in different positions of the bed were studied.The result revealed that the size and number of bubbles is correlated with the fine coal separation effect in the separation process.When the bed is in a uniform and stable fluidized state,the size of bubbles in the separation process was in the range of 1-2.5 cm and the number of bubbles was reduced by nearly 50%,which is helpful to promote the stratification and segregation of fine coal.Thereby,after separation,the ash content of refined coal products of anthracite and 1/3 coking coal was reduced to 12.1% and 23.7% respectively,and the content of refined coal was up to 42.5% and 68.5% respectively,which show that the vibrated fluidized bed has a good separation performance,and can separate efficiently the coal of size−6+1 mm.展开更多
In order to improve the light welfare of Nile tilapia in aquaculture,the influence of hunger level on light spectrum preference of Nile tilapia was explored in this study.The whole experiment was based on the emptying...In order to improve the light welfare of Nile tilapia in aquaculture,the influence of hunger level on light spectrum preference of Nile tilapia was explored in this study.The whole experiment was based on the emptying of the gastrointestinal contents,and carried out under the controlled laboratory conditions.The light spectrum preference was assessed by counting the head location of fish in each experimental tank,which containing seven compartments(i.e.,red,blue,white,yellow,black,green and public area).t-Distributed Stochastic Neighbor Embedding(t-SNE)was adopted to visualize the hunger level-based dynamic preference on light spectrum in two-dimensional space.According to the clustering results,significant differences in light spectrum preferences of Nile tilapia,under the different hunger levels,were indicated.In addition,the average visit frequency in green compartment was significantly lower than that in other color compartments throughout the whole experiment,and the total visit frequency in red compartment was relatively higher during the whole experiment.展开更多
The authors regret that the printed version of the above article contained a number of errors which were not identified during the proofing stage.The correct and final version follows.The authors would like to apologi...The authors regret that the printed version of the above article contained a number of errors which were not identified during the proofing stage.The correct and final version follows.The authors would like to apologies for any inconvenience caused.The authors regret:1.“…and the underlying molecular mechanism of this simulation is yet to be determined”,Page 335,needs to be corrected to“and the underlying molecular mechanism of this stimulation is yet to be determined”.展开更多
Detailed routing has become much challenging in modern circuit designs due to the extreme scaling of chip size and the complicated design rules.In this paper,we give an effective algorithm for detailed routing conside...Detailed routing has become much challenging in modern circuit designs due to the extreme scaling of chip size and the complicated design rules.In this paper,we give an effective algorithm for detailed routing considering advanced technology nodes.First,we present a valid pin-access candidates generation technology for handling complex pin shapes.Then,we propose a tree-based nets components selection algorithm to decide connecting order for multiple nets components.Finally,combined with global routing results and advanced technology nodes,an initial routing results optimization algorithm is presented to achieve the final detailed routing results.Experimental results on industry benchmarks show that,our proposed algorithm not only achieves 100%routability on real industrial cases in a reasonable runtime,but also optimizes total wirelength,total vias and other advanced technology nodes simultaneously.展开更多
The purpose of this study is to reveal the genetic mechanism of the variation of amylose content among different semi waxy or glutinous japonica rice in the background of Wxmp gene.Sixty-four semi waxy lines derived f...The purpose of this study is to reveal the genetic mechanism of the variation of amylose content among different semi waxy or glutinous japonica rice in the background of Wxmp gene.Sixty-four semi waxy lines derived from the hybrid progenies of Wujing 13 and Milky Princess(Kantou 194)with polymorphism in soluble starch synthase gene SSIIa(SSII-3)and SSIIIa(SSIII-2)but no polymorphism in other starch synthase related genes were used as test materials.The genotypes of SSIIa and SSIIIa allele were identified by molecular markers,and the allelic effects of SSIIa and SSIIIa gene on amylose content(AC),gel consistency(GC),gelatinization temperature(GT)and rapid visco analyzer(RVA)profile characteristics were analyzed.The significant effects of SSIIa and SSIIIa alleles and the interactive effects between two genes on AC,GT,GC and RVA profile characteristics were found.The SSIIa and SSIIIa alleles from Wujing13 shown positive effects on AC with an average increase of 1.87 and 1.23%in 2 years respectively.There was no significant effect on GT for SSIIa or SSIIIa allele but remarkable influence on GT when the co-existence of the two genes.The genotype SSIIa^(mp)SSIIIa^(mp) shown 1.34℃higher GT than genotype SSIIawjSSIIIawj(mp and wj indicated that the gene was derived from Milky Princess and Wujing 13 respectively,the same as in the below).Different genes and alleles resulted in significant different GC.The genetic effect of SSIIawj and SSIIIamp on GC was 8.74 and 9.62mm respectively.The GC of SSIIa^(wj)SSIIIa^(mp) was 10.64 and 16.95mm higher than that of SSIIa^(mp)SSIIIa^(wj) and SSIIawjSSIIIawj,respectively.The allele SSIIa^(wj) could increase the peak viscosity(PKV),hot paste viscosity(HPV),cool paste viscosity(CPV)and breakdown viscosity(BDV),while decrease the consistency viscosity(CSV)and setback viscosity(SBV).However for the allele SSIIIa^(wj) the opposite was true.The genotype SSIIa^(wj)SSIIIa^(mp) had the largest PKV,HPV and CPV,the genotype SSIIa^(wj)SSIIIa^(wj) had the largest BDV and CSV,but the genotype SSIIa^(wj)SSIIIa^(mp) had the least SBV.According to the comprehensive effect of each trait,the genotype SSIIawjSSIIIamp was the best.The allelic variation and interaction effect of SSIIa and SSIIIa genes have important reference value for improving cooking and eating quality of semi waxy japonica rice.展开更多
基金supported in part by National Key R&D Program of China(Grant No.2016YFE0205200)High-Speed Railway Basic Research Fund Key Project of China(Grant No.U1234208)+1 种基金National Natural Science Foundation of China(Grant No.11972179,51475394)China Postdoctoral Science Foundation Grant(Grant No.2019M662201).
文摘The object of research of this paper is the DSA380 high-speed pantograph.The near-field unsteady flow around the pantograph was investigated using large eddy simulation(LES)while the far-field aerodynamic noise was analysed in the frame of the Ffowcs Williams-Hawkings(FW-H)acoustic analogy.According to the results,the contact strip,base frame and knuckle are the main aerodynamic noise sources,with vortex shedding,flow separation and recombination around the pantograph being related key physical factors.The aerodynamic noise radiates outwards in the form of spherical waves when the distance of the noise receiving point is farther than 8 m.The sound pressure level(SPL)grows approximately as the 6th power of pantograph operating speed.The aerodynamic noise energy is mainly concentrated in the region of 400-1000 Hz,and the frequency band is wider with crosswind than without crosswind.The peak frequency displays a linear relationships with the operating speed and crosswind velocity,respectively.The aerodynamic and aeroacoustic generation from the knuckle-downstream orientation of the pantograph is superior to those of the knuckle-upstream orientation model.This finding may be used for the optimal design of future pantograph configurations in the presence of crosswind.
文摘The thermal decomposition process was studied by the TG–DTA analyzer. The results show that the decomposition process of sodium hydroxyethyl sulfonate consisted of three stages: the mass loss for the first, the second and third stages may be about the groups of CH_3CH_2OH, CH_3CHO and SO_2 volatilized, respectively. The decomposition residuum of three stages was analyzed by FT-IR, and the results of FT-IR agreed with the decomposition process predicted by theoretical weight loss. The specific heat capacity of sodium hydroxyethyl sulfonate was determined by differential scanning calorimetry(DSC). The melting temperature and melting enthalpy were obtained to be 465.41 K and 25.69 kJ·mol^(-1), respectively. The molar specific heat capacity of sodium hydroxyethyl sulfonate was determinated from 310.15 K to 365.15 K and expressed as a function of temperature.
基金financially supported by the National Natural Science Foundation of China(21706240)。
文摘The liquid phase oxidation of cyclohexylbenzene(CHB)is a new green synthetic approach to cyclohexylbenzene-1-hydroperoxide(CHBHP),a key intermediate for preparing phenol and cyclohexanone.In this work,aryl-substituted(Cl and Br)derivatives of N-hydroxyphthalimide(NHPI)were synthesized and their catalytic performances for CHB oxidation were studied.In addition,geometric optimization and transition state search were performed using DFT calculations.Both experimental and theoretical studies have proven that chloro-substitution on NHPI can significantly improve its catalytic effects on the oxidation of CHB by oxygen.Compared with NHPI,CHB conversion and selectivity of CHBHP over Cl;NHPI were increased by 10.47%and 13.24%.The strategy of aryl-substituting NHPI with halogen atoms proposed in this study would provide a potential way to the development of new NHPI-based catalysts for aerobic oxidation reactions.
基金supported by the National Natural Science Foundation of China under grant nos.61772091,61802035,61962006,61962038,U1802271,U2001212,and 62072311the Sichuan Science and Technology Program under grant nos.2021JDJQ0021 and 22ZDYF2680+7 种基金the CCF‐Huawei Database System Innovation Research Plan under grant no.CCF‐HuaweiDBIR2020004ADigital Media Art,Key Laboratory of Sichuan Province,Sichuan Conservatory of Music,Chengdu,China under grant no.21DMAKL02the Chengdu Major Science and Technology Innovation Project under grant no.2021‐YF08‐00156‐GXthe Chengdu Technology Innovation and Research and Development Project under grant no.2021‐YF05‐00491‐SNthe Natural Science Foundation of Guangxi under grant no.2018GXNSFDA138005the Guangdong Basic and Applied Basic Research Foundation under grant no.2020B1515120028the Science and Technology Innovation Seedling Project of Sichuan Province under grant no 2021006the College Student Innovation and Entrepreneurship Training Program of Chengdu University of Information Technology under grant nos.202110621179 and 202110621186.
文摘An excellent cardinality estimation can make the query optimiser produce a good execution plan.Although there are some studies on cardinality estimation,the prediction results of existing cardinality estimators are inaccurate and the query efficiency cannot be guaranteed as well.In particular,they are difficult to accurately obtain the complex relationships between multiple tables in complex database systems.When dealing with complex queries,the existing cardinality estimators cannot achieve good results.In this study,a novel cardinality estimator is proposed.It uses the core techniques with the BiLSTM network structure and adds the attention mechanism.First,the columns involved in the query statements in the training set are sampled and compressed into bitmaps.Then,the Word2vec model is used to embed the word vectors about the query statements.Finally,the BiLSTM network and attention mechanism are employed to deal with word vectors.The proposed model takes into consideration not only the correlation between tables but also the processing of complex predicates.Extensive experiments and the evaluation of BiLSTM-Attention Cardinality Estimator(BACE)on the IMDB datasets are conducted.The results show that the deep learning model can significantly improve the quality of cardinality estimation,which is a vital role in query optimisation for complex databases.
基金the National Natural Science Foundation of China(Grant Nos.61774168 and 11764008)the Opening Project of Key Laboratory of Microelectronic Devices&Integrated Technology,Institute of Microelectronics,Chinese Academy of Sciences。
文摘Since defects such as traps and oxygen vacancies exist in dielectrics,it is difficult to fabricate a high-performance MoS_(2)field-effect transistor(FET)using atomic layer deposition(ALD)Al_(2)O_(3)as the gate dielectric layer.In this paper,NH_(3)in situ doping,a process treatment approach during ALD growth of Al_(2)O_(3),is used to decrease these defects for better device characteristics.MoS_(2)FET has been well fabricated with this technique and the effect of different NH_(3)in situ doping sequences in the growth cycle has been investigated in detail.Compared with counterparts,those devices with NH_(3)in situ doping demonstrate obvious performance enhancements:Ion/Ioff is improved by one order of magnitude,from 1.33×10^(5)to 3.56×10^(6),the threshold voltage shifts from-0.74 V to-0.12 V and a small subthreshold swing of 105 m V/dec is achieved.The improved MoS_(2)FET performance is attributed to nitrogen doping by the introduction of NH_(3)during the Al_(2)O_(3)ALD growth process,which leads to a reduction in the surface roughness of the dielectric layer and the repair of oxygen vacancies in the Al_(2)O_(3)layer.Furthermore,the MoS_(2)FET processed by in situ NH_(3)doping after the Al and O precursor filling cycles demonstrates the best performance;this may be because the final NH_(3)doping after film growth restores more oxygen vacancies to screen more charge scattering in the MoS_(2)channel.The reported method provides a promising way to reduce charge scattering in carrier transport for high-performance MoS_(2)devices.
文摘Based on H1-Galerkin mixed finite element method with nonconforming quasi-Wilson element, a numerical approximate scheme is established for pseudo-hyperbolic equations under arbitrary quadrilateral meshes. The corresponding optimal order error estimate is derived by the interpolation technique instead of the generalized elliptic projection which is necessary for classical error estimates of finite element analysis.
基金National Natural Science Foundation of China,Grant/Award Number:21871129。
文摘The crystal phases are essential to the physicochemical properties and functionalities of materials.Copper selenide has emerged as an important and appealing semiconductor,which can exist in a variety of polymorphic phases.However,the richness of polymorphs also makes it a challenge to the direct preparation of copper selenide nanocrystals with tunable phases.Herein,two polymorphs,that is,quasitetragonal Cu2−xSe nanocubes and metastable wurtzite Cu2Se nanodisks,are successfully synthesized by using a single precursor,copper(I)selenocyanate(CuSeCN),as the Cu and Se sources.The key to phase modulation is the optimal choice of the ligand in the synthesis.The as‐prepared nanocrystals possess different morphologies and compositions,giving rise to distinct optical properties and electrical conductivities.Interestingly,the copper selenide nanocrystals can provide a platform for the rational construction of two types of amorphous hollow Au─Cu─Se nanostructures by reaction with Au(I)precursor,in which their final shapes are well kept as that of the original nanocrystal templates.This work provides an easy strategy for the phase‐controlled synthesis of copper selenide nanocrystals and enables the design of new materials for broad applications.
基金This work was supported by grants from the Strategic PriorityResearch Program of Chinese Academy of Sciences(GrantNos.XDA19090116,XDA19050302,and XDB38030400)awarded to SS,ZZ,and MLthe National Key R&D Programof China(Grant Nos.2020YFC0848900,2020YFC0847000,2016YFE0206600,and 2017YFC0907502)+5 种基金the 13th Five-yearInformatization Plan of Chinese Academy of Sciences(GrantNo.XXH13505-05)Genomics Data Center Construction ofChinese Academy of Sciences(Grant No.XXH-13514-0202)the Open Biodiversity and Health Big Data Programme ofInternational Union of Biological Sciences,International Part-nership Program of Chinese Academy of Sciences(Grant No.153F11KYSB20160008)the Professional Association of theAlliance of International Science Organizations(Grant No.ANSO-PA-2020-07)This work was also supported by KCWong Education Foundation to ZZthe YouthInnovation Promotion Association of Chinese Academy ofSciences(Grant Nos.2017141 and 2019104)awarded to SSand ML.
文摘On January 22,2020,China National Center for Bioinformation(CNCB)released the 2019 Novel Coronavirus Resource(2019nCoVR),an open-access information resource for the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).2019nCoVR features a comprehensive integration of sequence and clinical information for all publicly available SARS-CoV-2 isolates,which are manually curated with value-added annotations and quality evaluated by an automated in-house pipeline.Of particular note,2019nCoVR offers systematic analyses to generate a dynamic landscape of SARS-CoV-2 genomic variations at a global scale.It provides all identified variants and their detailed statistics for each virus isolate,and congregates the quality score,functional annotation,and population frequency for each variant.Spatiotemporal change for each variant can be visualized and historical viral haplotype network maps for the course of the outbreak are also generated based on all complete and high-quality genomes available.Moreover,2019nCoVR provides a full collection of SARS-CoV-2 relevant literature on the coronavirus disease 2019(COVID-19),including published papers from PubMed as well as preprints from services such as bioRxiv and medRxiv through Europe PMC.Furthermore,by linking with relevant databases in CNCB,2019nCoVR offers data submission services for raw sequence reads and assembled genomes,and data sharing with NCBI.Collectively,SARS-CoV-2 is updated daily to collect the latest information on genome sequences,variants,haplotypes,and literature for a timely reflection,making 2019nCoVR a valuable resource for the global research community.2019nCoVR is accessible at https://bigd.big.ac.cn/ncov/.
基金the National Natural Science Foundation of China(grant Nos.51704287 and 51620105001).
文摘Pulsed gas-solid fluidized beds can effectively separate fine coal,and bubbles play an important role in creating suitable separation conditions.The present study performed statistical and image analyses of the evolution of bubbles in a two-dimensional pulsed gas-solid fluidized bed using a high-speed dynamic camera.The effects of apparent gas velocity,pulsation frequency and particle size on bubble characteristics and bed expansi on were analyzed.The results indicate that,when a fluctuation freque ncy is added,the expa nsion height of the bed in creases,the effect of attachme nt to the bed wall decreases,the leading diameter and rising velocity of the bubbles both decrease and the degree of bubble deformation increases.These trends are also more obvious for fine particles.These findings dem on strate that a high density pulsed gas-solid fluidized bed can effectively combine gases and solids to produce a uniform,stable mixture.The bubble diameter and rising velocity were also simulated in the present work,and the relationship between the two was established using a fitting model with an error within 5%.This model provides an effective means of predicting bubble velocity as well as studying the distribution of the bubble phase and improving the stability of the bed density.
基金This study received support from the National Key R&D Program of China(No.2020YFD0900600)the Key Program of Science and Technology of Zhejiang Province(2019C02084).
文摘In recent years,government investments in implementing restrictive public policies on the treatment and discharge of effluents from the aquaculture industry have increased.Hence,efficient and cleaner methods for aquaculture production are needed.Recirculating aquaculture systems(RAS)offers water conservation by recycling the treated aquaculture water for reuse.RAS wastewater treatment using a moving bed bioreactors(MBBRs)process has been considered well suited for maintaining good water quality,thereby making fish farming more sustainable.Currently,improvements were achieved in tackling the influence of salinity,organic matter,disinfectant,and bioreactor start-up process on the MBBR performance efficiency.This review highlights an updated overview of recent development made using MBBR to treat the residual water from RAS.Precisely,nitrification and simultaneous nitrification-denitrification(SND),and other hybrid processes for nitrogen removal were elucidated.Finally,future challenges and prospects of MBBRs in RAS facilities that need to be considered were also proposed.
基金supported by the National Key R&D Program of China(Grant No.2018YFC1106300 , 2017YFC1105000)the National Natural Science Foundation of China(Grant No.51802340,31870956,31771041 , 81672227)+6 种基金the Science and Technology Project of Guangdong Province-Doctoral startup fund of 2017(Grant No.2017A030310318)the Frontier Science Key Research Programs of CAS(Grant No.QYZDB-SSW-JSC030)the Strategic Priority Research Program of CAS(Grant No.XDA16021000)the Shenzhen significant strategy layout project(Grant No.JCYJ20170413162104773)the Economic,Trade and information Commission of Shenzhen Municipality“Innovation and Industry Chain”(Grant No.20170502171625936)the Beijing Municipal Natural Science Foundation(Grant No.7161001)Beijing Municipal Commission of Health and Family Planning(Grant No.PXM2018_026275_000001).
文摘There is a need for synthetic grafts to reconstruct large bone defects using minimal invasive surgery.Our previous study showed that incorporation of Sr into bioactive borate glass cement enhanced the osteogenic capacity in vivo.However,the amount of Sr in the cement to provide an optimal combination of physicochemical properties and capacity to stimulate bone regeneration and the underlying molecular mechanism of this stimulation is yet to be determined.In this study,bone cements composed of bioactive borosilicate glass particles substituted with varying amounts of Sr(0 mol%to 12 mol%SrO)were created and evaluated in vitro and in vivo.The setting time of the cement increased with Sr substitution of the glass.Upon immersion in PBS,the cement degraded and converted more slowly to HA(hydroxyapatite)with increasing Sr substitution.The released Sr2+modulated the proliferation,differentiation,and mineralization of hBMSCs(human bone marrow mesenchymal stem cells)in vitro.Osteogenic characteristics were optimally enhanced with cement(designated BG6Sr)composed of particles substituted with 6mol%SrO.When implanted in rabbit femoral condyle defects,BG6Sr cement supported better peri-implant bone formation and bone-implant contact,comparing to cements substituted with 0mol%or 9mol%SrO.The underlying mechanism is involved in the activation of Wnt/β-catenin signaling pathway in osteogenic differentiation of hBMSCs.These results indicate that BG6Sr cement has a promising combination of physicochemical properties and biological performance for minimally invasive healing of bone defects.
基金supported by the National Natural Science Foundation of China(Nos.51321064 and 51378015)
文摘A decay function for the layering effect during the projectile penetrating into layered targets is constructed, which is obtained via the theoretical solution of a dynamically expanding layered spherical cavity with finite radius in the layered targets that are assumed to be incompressible Mohr-Coulomb materials. By multiplying the decay function with the semi-empirical forcing functions that account for all the constitutive behavior of the targets, the forcing functions for the layered targets are obtained. Then, the forcing functions are used to represent the targets and are applied on the projectile surface as the pressure boundary condition where the projectile is modeled by an explicit transient dynamic finite element code. This methodology is implemented into ABAQUS explicit solver via the user subroutine VDLOAD, which eliminates the need for discretizing the targets and the need for the complex contact algorithm. In order to verify the proposed layering effect model, depth-of-penetration experiments of the 37 mm hard core projectile penetrating into three sets of fiber concrete and soil layered targets are conducted. The predicted depths of penetration show good agreement with the experimental data. Furthermore,the influence of layering effect on projectile trajectory during earth penetration is investigated. It is found that the layering effect should be taken into account if the final position and trajectory of the projectile are the main concern.
基金Financial supports by the Found of the Jiangsu Excellent Youth Fund Project(Grant No.BK20200087)the National Natural Science Foundation of China(Grant Nos.51904298,U20A20304,51974306,51620105001)are gratefully acknowledged.
文摘In this paper,the variation of bubble size and number in the separation process of vibrated fluidized bed as well as the influence of bubble movement on the axial distribution of fine coal in different positions of the bed were studied.The result revealed that the size and number of bubbles is correlated with the fine coal separation effect in the separation process.When the bed is in a uniform and stable fluidized state,the size of bubbles in the separation process was in the range of 1-2.5 cm and the number of bubbles was reduced by nearly 50%,which is helpful to promote the stratification and segregation of fine coal.Thereby,after separation,the ash content of refined coal products of anthracite and 1/3 coking coal was reduced to 12.1% and 23.7% respectively,and the content of refined coal was up to 42.5% and 68.5% respectively,which show that the vibrated fluidized bed has a good separation performance,and can separate efficiently the coal of size−6+1 mm.
基金supported by the National Key R&D Program of China(Grant No.2017YFB0404000)the Key R&D Program of Ningxia Hui Autonomous Region(Grant No.2018BBF02009)Open Fund of Yunnan Province Key Laboratory of Food Processing and Safety Control(Grant No.K16-507106-007)。
文摘In order to improve the light welfare of Nile tilapia in aquaculture,the influence of hunger level on light spectrum preference of Nile tilapia was explored in this study.The whole experiment was based on the emptying of the gastrointestinal contents,and carried out under the controlled laboratory conditions.The light spectrum preference was assessed by counting the head location of fish in each experimental tank,which containing seven compartments(i.e.,red,blue,white,yellow,black,green and public area).t-Distributed Stochastic Neighbor Embedding(t-SNE)was adopted to visualize the hunger level-based dynamic preference on light spectrum in two-dimensional space.According to the clustering results,significant differences in light spectrum preferences of Nile tilapia,under the different hunger levels,were indicated.In addition,the average visit frequency in green compartment was significantly lower than that in other color compartments throughout the whole experiment,and the total visit frequency in red compartment was relatively higher during the whole experiment.
文摘The authors regret that the printed version of the above article contained a number of errors which were not identified during the proofing stage.The correct and final version follows.The authors would like to apologies for any inconvenience caused.The authors regret:1.“…and the underlying molecular mechanism of this simulation is yet to be determined”,Page 335,needs to be corrected to“and the underlying molecular mechanism of this stimulation is yet to be determined”.
文摘Detailed routing has become much challenging in modern circuit designs due to the extreme scaling of chip size and the complicated design rules.In this paper,we give an effective algorithm for detailed routing considering advanced technology nodes.First,we present a valid pin-access candidates generation technology for handling complex pin shapes.Then,we propose a tree-based nets components selection algorithm to decide connecting order for multiple nets components.Finally,combined with global routing results and advanced technology nodes,an initial routing results optimization algorithm is presented to achieve the final detailed routing results.Experimental results on industry benchmarks show that,our proposed algorithm not only achieves 100%routability on real industrial cases in a reasonable runtime,but also optimizes total wirelength,total vias and other advanced technology nodes simultaneously.
基金supported by Jiangsu Natural Science Foundation(No.BK20180302)Jiangsu agricultural science and Technology Innovation Fund(No.CX[18]1001)+3 种基金Jiangsu Key Research and development program(No.BE2018357)Jiangsu major new varieties creation project(No.PZCZ201703)the earmarked fund for China Agriculture Research System(No.CARS-1-62)the open project of key Laboratory of Jiangsu crop genomics and molecular Breeding(No.PL201902).
文摘The purpose of this study is to reveal the genetic mechanism of the variation of amylose content among different semi waxy or glutinous japonica rice in the background of Wxmp gene.Sixty-four semi waxy lines derived from the hybrid progenies of Wujing 13 and Milky Princess(Kantou 194)with polymorphism in soluble starch synthase gene SSIIa(SSII-3)and SSIIIa(SSIII-2)but no polymorphism in other starch synthase related genes were used as test materials.The genotypes of SSIIa and SSIIIa allele were identified by molecular markers,and the allelic effects of SSIIa and SSIIIa gene on amylose content(AC),gel consistency(GC),gelatinization temperature(GT)and rapid visco analyzer(RVA)profile characteristics were analyzed.The significant effects of SSIIa and SSIIIa alleles and the interactive effects between two genes on AC,GT,GC and RVA profile characteristics were found.The SSIIa and SSIIIa alleles from Wujing13 shown positive effects on AC with an average increase of 1.87 and 1.23%in 2 years respectively.There was no significant effect on GT for SSIIa or SSIIIa allele but remarkable influence on GT when the co-existence of the two genes.The genotype SSIIa^(mp)SSIIIa^(mp) shown 1.34℃higher GT than genotype SSIIawjSSIIIawj(mp and wj indicated that the gene was derived from Milky Princess and Wujing 13 respectively,the same as in the below).Different genes and alleles resulted in significant different GC.The genetic effect of SSIIawj and SSIIIamp on GC was 8.74 and 9.62mm respectively.The GC of SSIIa^(wj)SSIIIa^(mp) was 10.64 and 16.95mm higher than that of SSIIa^(mp)SSIIIa^(wj) and SSIIawjSSIIIawj,respectively.The allele SSIIa^(wj) could increase the peak viscosity(PKV),hot paste viscosity(HPV),cool paste viscosity(CPV)and breakdown viscosity(BDV),while decrease the consistency viscosity(CSV)and setback viscosity(SBV).However for the allele SSIIIa^(wj) the opposite was true.The genotype SSIIa^(wj)SSIIIa^(mp) had the largest PKV,HPV and CPV,the genotype SSIIa^(wj)SSIIIa^(wj) had the largest BDV and CSV,but the genotype SSIIa^(wj)SSIIIa^(mp) had the least SBV.According to the comprehensive effect of each trait,the genotype SSIIawjSSIIIamp was the best.The allelic variation and interaction effect of SSIIa and SSIIIa genes have important reference value for improving cooking and eating quality of semi waxy japonica rice.