In order to realize seedbed mechanization of whole plastic-film mulching on double ridges and to overcome the difficulty in crosswise belt type soil covering by whole plastic-film,a kind of crosswise belt type whole p...In order to realize seedbed mechanization of whole plastic-film mulching on double ridges and to overcome the difficulty in crosswise belt type soil covering by whole plastic-film,a kind of crosswise belt type whole plastic-film ridging-mulching corn seeder on double ridges was designed in this study.The key components of the sample machine was designed and its working parameters of seedbed soil covering device,crosswise-belt soil covering mechanism and profiling sowing depth adjustment device were determined.After numerical simulation on the film edge and crosswise soil covering by whole plastic-film on double ridges by discrete element method,the velocity and displacement of the oscillating plate,and the variation rule of amount of covered soil with time were explored.Field test results show that,when the advancing velocity of the machine was 0.50 m/s,the qualified rate of soil width covered on film edge of the seedbed reached 96.1%,qualified rate of crosswise soil belt width was 94.5%,qualified rate of soil thickness on seedbed was 95.3%,qualified rate of sowing depth was 89.3%,qualified rate of spacing between crosswise soil belts reached 93.6%,which all met related standards in China and satisfied design requirements,and could realize seedbed mechanization of whole plastic-film mulching on double ridges.Comparison tests on working performances of practical soil covering show a basic consistence with the seedbed soil covering simulation,and verified the effectiveness of the soil covering model built by using discrete element method.展开更多
In order to further improve the working performance and efficiency of mechanized tillage operation of a full-film double-ditch seedbed,under the working conditions of different parameters of the spiral push-type soil ...In order to further improve the working performance and efficiency of mechanized tillage operation of a full-film double-ditch seedbed,under the working conditions of different parameters of the spiral push-type soil covering device with double-width filming,the dynamic soil covering characteristics and soil covering uniformity of the device were analyzed,the collaborative and interactive coupling mechanism of the horizontal pushing process of the mulching soil and horizontally two-way spiral soil transmission device were revealed,and the main reasons for the influence of different soil covering belts on the change of soil particle number distribution were analyzed.Based on the full-film double-ditch mode with double-width filming,the mechanized soil covering path was optimized.In order to further reduce the disturbance on mulching soil by two-way spiral pushing,a kind of parallel shunt type soil covering device with double-width filming was designed,then a discrete element method was adopted to make simulation analysis and optimize the parallel shunt type soil covering device with double-width filming.Field verification tests showed that after the operation of the full-film double-ditch combined machine with double-width filming and soil covering installed with the parallel shunt type soil covering device,the qualified rate of the film edge soil covering width was 96.1%,an increase of 1.6%compared to that before optimization;the qualified rate of soil covering width at the center of the big ridge was 93.5%,an increase of 1.9%compared to that before optimization;the qualified rate of the soil covering thickness was 97.7%,an increase of 0.2%compared to that before optimization.The test indicators reached the requirements of relevant national and industrial standards,showing that the test results met the design requirements,and the working conditions of verification tests were consistent with the simulation results.展开更多
Let Y be a smooth projective surface defined over an algebraically closed field k with char k ≠ 2, and let π ： X → Y be a double covering branched along a smooth divisor. We show that Jx is stable with respect to...Let Y be a smooth projective surface defined over an algebraically closed field k with char k ≠ 2, and let π ： X → Y be a double covering branched along a smooth divisor. We show that Jx is stable with respect to π＊H if the tangent bundle Jy is semi-stable with respect to some ample line bundle H on Y.展开更多
In this series of papers, surfaces of general-type with X(O_s)=1 and fibrations of genus 2 are classified completely, and some new surfaces with invariant p_8=0 are constructed This paper will set up two kinds of nume...In this series of papers, surfaces of general-type with X(O_s)=1 and fibrations of genus 2 are classified completely, and some new surfaces with invariant p_8=0 are constructed This paper will set up two kinds of numerical Campedelli surfaces with fibrations of genus 2.展开更多
The spectra of generalized Cayley graphs of finite abelian groups are investigated in this paper.For a generalized Cayley graph X of a finite group G,the canonical double covering of X is the direct product X×K_(...The spectra of generalized Cayley graphs of finite abelian groups are investigated in this paper.For a generalized Cayley graph X of a finite group G,the canonical double covering of X is the direct product X×K_(2).In this paper,integral generalized Cayley graphs on finite abelian groups are characterized,using the characterization of the spectra of integral Cayley graphs.As an application,the integral generalized Cayley graphs on Z_(p)×Z_(q) and Z2n are investigated,where p and q are odd prime numbers.展开更多
Llex cornuta var.fortunei S.Y.Hu is a good ornamental tree species for viewing fruits and leaves,and has a wide range of garden uses.Nutrition bowl cutting seedlings can improve the survival rate of L.cornut a var.for...Llex cornuta var.fortunei S.Y.Hu is a good ornamental tree species for viewing fruits and leaves,and has a wide range of garden uses.Nutrition bowl cutting seedlings can improve the survival rate of L.cornut a var.fortunei S.Y.Hu transplanting and greening,and has the advantages of no time limit for planting and saving management costs.Based on this,this paper introduced the container seedling double-covering cutting technology for L.cornut a var.fortunei,to provide a reference for the propagation of L.cornut a var.fortunei.展开更多
基金The authors acknowledge that this work was financially supported by National Natural Science Foundation of China(Grant No.51775115No.51405086)China Agriculture Research System(CARS-14-1-28).
文摘In order to realize seedbed mechanization of whole plastic-film mulching on double ridges and to overcome the difficulty in crosswise belt type soil covering by whole plastic-film,a kind of crosswise belt type whole plastic-film ridging-mulching corn seeder on double ridges was designed in this study.The key components of the sample machine was designed and its working parameters of seedbed soil covering device,crosswise-belt soil covering mechanism and profiling sowing depth adjustment device were determined.After numerical simulation on the film edge and crosswise soil covering by whole plastic-film on double ridges by discrete element method,the velocity and displacement of the oscillating plate,and the variation rule of amount of covered soil with time were explored.Field test results show that,when the advancing velocity of the machine was 0.50 m/s,the qualified rate of soil width covered on film edge of the seedbed reached 96.1%,qualified rate of crosswise soil belt width was 94.5%,qualified rate of soil thickness on seedbed was 95.3%,qualified rate of sowing depth was 89.3%,qualified rate of spacing between crosswise soil belts reached 93.6%,which all met related standards in China and satisfied design requirements,and could realize seedbed mechanization of whole plastic-film mulching on double ridges.Comparison tests on working performances of practical soil covering show a basic consistence with the seedbed soil covering simulation,and verified the effectiveness of the soil covering model built by using discrete element method.
基金the National Natural Science Foundation of China(Grant No.52065005,No.51775115)Outstanding Youth Foundation of Gansu Province(Grant No.20JR10RA560)+1 种基金Natural Science Foundation of Gansu Province(Grant No.20JR5RA029)Research Program Sponsored by Gansu Provincial Key Laboratory of Aridland Crop Science,Gansu Agricultural University(Grant No.GSCS-2020-01).
文摘In order to further improve the working performance and efficiency of mechanized tillage operation of a full-film double-ditch seedbed,under the working conditions of different parameters of the spiral push-type soil covering device with double-width filming,the dynamic soil covering characteristics and soil covering uniformity of the device were analyzed,the collaborative and interactive coupling mechanism of the horizontal pushing process of the mulching soil and horizontally two-way spiral soil transmission device were revealed,and the main reasons for the influence of different soil covering belts on the change of soil particle number distribution were analyzed.Based on the full-film double-ditch mode with double-width filming,the mechanized soil covering path was optimized.In order to further reduce the disturbance on mulching soil by two-way spiral pushing,a kind of parallel shunt type soil covering device with double-width filming was designed,then a discrete element method was adopted to make simulation analysis and optimize the parallel shunt type soil covering device with double-width filming.Field verification tests showed that after the operation of the full-film double-ditch combined machine with double-width filming and soil covering installed with the parallel shunt type soil covering device,the qualified rate of the film edge soil covering width was 96.1%,an increase of 1.6%compared to that before optimization;the qualified rate of soil covering width at the center of the big ridge was 93.5%,an increase of 1.9%compared to that before optimization;the qualified rate of the soil covering thickness was 97.7%,an increase of 0.2%compared to that before optimization.The test indicators reached the requirements of relevant national and industrial standards,showing that the test results met the design requirements,and the working conditions of verification tests were consistent with the simulation results.
文摘Let Y be a smooth projective surface defined over an algebraically closed field k with char k ≠ 2, and let π ： X → Y be a double covering branched along a smooth divisor. We show that Jx is stable with respect to π＊H if the tangent bundle Jy is semi-stable with respect to some ample line bundle H on Y.
文摘In this series of papers, surfaces of general-type with X(O_s)=1 and fibrations of genus 2 are classified completely, and some new surfaces with invariant p_8=0 are constructed This paper will set up two kinds of numerical Campedelli surfaces with fibrations of genus 2.
基金supported by the National Natural Science Foundation of China(No.12271311,12101410,12201414)Taishan Scholars Program of Shandong Province.
文摘The spectra of generalized Cayley graphs of finite abelian groups are investigated in this paper.For a generalized Cayley graph X of a finite group G,the canonical double covering of X is the direct product X×K_(2).In this paper,integral generalized Cayley graphs on finite abelian groups are characterized,using the characterization of the spectra of integral Cayley graphs.As an application,the integral generalized Cayley graphs on Z_(p)×Z_(q) and Z2n are investigated,where p and q are odd prime numbers.
文摘Llex cornuta var.fortunei S.Y.Hu is a good ornamental tree species for viewing fruits and leaves,and has a wide range of garden uses.Nutrition bowl cutting seedlings can improve the survival rate of L.cornut a var.fortunei S.Y.Hu transplanting and greening,and has the advantages of no time limit for planting and saving management costs.Based on this,this paper introduced the container seedling double-covering cutting technology for L.cornut a var.fortunei,to provide a reference for the propagation of L.cornut a var.fortunei.
