Rice is one of the most consumed staple food plants around the world, and its plant architecture is very important to improve the grain yield （Zhang et al., 2008）. Plant height, leaf angle, tiller number and angle, ...Rice is one of the most consumed staple food plants around the world, and its plant architecture is very important to improve the grain yield （Zhang et al., 2008）. Plant height, leaf angle, tiller number and angle, and uniformity of panicle layer all can have strong effects on grain yield （Wang and Li, 2008）. During the long history of domestication, rice has been selected to develop uniform tiller height architecture that ensures panicle layer uniformity and ease of harvesting （Ma et al., 2009）, and is largely determined by the synchronic culm elongation.展开更多
A physical value mapping （PVM） algorithm based on finite element mesh from the stamped part in stamping process to the product is presented, In order to improve the efficiency of the PVM algorithm, a search way from...A physical value mapping （PVM） algorithm based on finite element mesh from the stamped part in stamping process to the product is presented, In order to improve the efficiency of the PVM algorithm, a search way from the mesh of the product to the mesh of the stamped part will be adopted. At the same time, the search process is divided into two steps： entire search （ES） and local search （LS）, which improve the searching efficiency. The searching area is enlarged to avoid missing projection elements in ES process. An arc-length method is introduced in LS process. The validity is confirmed by the results of the complex industry-forming product.展开更多
Micro electrical discharge machining（EDM） deposition process is a new micro machining method for fabrication of metal micro structures. In this process, the high level of tool electrode wear is used to achieve the m...Micro electrical discharge machining（EDM） deposition process is a new micro machining method for fabrication of metal micro structures. In this process, the high level of tool electrode wear is used to achieve the metal material deposition. Up to now, the studies of micro EDM deposition process focused mainly on the researches of deposition process, namely the effects of discharge parameters in deposition process on the deposition rate or deposition quality. The research of the formation of micro structures with different discharge energy density still lacks. With proper conditions and only by the z-axis feeding in vertical direction, a novel shape of micro spiral structure can be deposited, with 0.11 mm in wire diameter, 0.20 mm in outside diameter, and 3.78 mm in height. Then some new deposition strategies including angular deposition and against the gravity deposition were also successful. In order to find the forming mechanism of the spiral structures, the numerical simulation of the transient temperature distribution on the discharge point was conducted by using the finite-element method（FEM）. The results show that there are two major factors lead to the forming of the spiral structures. One is the different material removal form of tool electrode according with the discharge energy density, the other is the influenced degree of the movement of the removed material particles in the discharge gap. The more the energy density in single discharge is, the smaller the mass of the removed material particles is, and the easier the movements of which will be changed to form an order tendency. The fine texture characteristics of the deposited micro spiral structures were analyzed by the energy spectrum analysis and the metallographic analysis. It shows that the components of the deposited material are almost the same as those of the tool electrode. Moreover the deposited material has the brass metallic luster in the longitudinal profile and has compact bonding with the base material. This research is useful to understand the micro-process of micro EDM deposition better and helpful to increase the controllability of the new EDM method for fabrication of micro structures.展开更多
The flotation process is a particle-hydrophobic surface-based separation technique. To improve the essential flotation steps of collision and attachment probabilities, and reduce the step of detachment probabilities b...The flotation process is a particle-hydrophobic surface-based separation technique. To improve the essential flotation steps of collision and attachment probabilities, and reduce the step of detachment probabilities between air bubbles and hydrophobic particles, a selectively designed cavitation venturi tube combined with a static mixer can be used to generate very high numbers of pico and nano bubbles in a flotation column. Fully embraced by those high numbers of tiny bubbles, hydrophobic particles readily attract the tiny bubbles to their surfaces. The results of column flotation of Pittsburgh No. 8 seam coal are obtained in a 5.08 cm ID and 162 cm height flotation column equipped with a static mixer and cavitation venturi tube, using kerosene as collector and MIBC as frother. Design of the experimental procedure is combined with a statistical two-stepwise analysis to determine the optimal operating conditions for maximum recovery at a specified grade. The effect of independent variables on the responses has been explained. Combustible material recovery of 85–90% at clean coal product of 10–11% ash is obtained from feed of 29.6% ash, with a much-reduced amount of frother and collector than that used in conventional column flotation. The column flotation process utilizing pico and nano bubbles can also be extended to the lower limit and upper limit of particle size ranges, minus 75 lm and 300–600 lm, respectively, for better recovery.展开更多
The enduring enigma surrounding the near-infrared(NIR)emission of Mn^(2+)continues to ignite intense academic discussions.Numerous hypotheses have emerged from extensive research endeavors to explain this phenomenon,s...The enduring enigma surrounding the near-infrared(NIR)emission of Mn^(2+)continues to ignite intense academic discussions.Numerous hypotheses have emerged from extensive research endeavors to explain this phenomenon,such as the formation of Mn^(2+)-Mn^(2+)ion pairs,Mn^(2+)occupying cubically coordinated sites,as well as conjectures positing the involvement of Mn3+oxidized from Mn^(2+)or defects.Despite these diverse and valuable insights,none of the hypotheses have yet achieved broad consensus.In this study,we have observed prolonged fluorescence lifetimes(~10ms)for the NIR emissions of Mn^(2+)ions,hinting at these ions occupying the high-symmetry octahedral sites inherent to the garnet lattice.This inference is supported by the corroborating results from X-ray absorption fine structure analysis and first-principles calculations.The intense crystal field of octahedral sites,similar to that of AlO6,facilitates the splitting of d-d energy levels,thereby inducing a red-shift in the emission spectrum to the NIR region due to the transition ^(4)T_(1)(4G)→ ^(6)A_(n)(6S)of isolated Mn^(2+).Our findings not only offer a plausible rationale for the NIR emission exhibited by other Mn^(2+)-activated garnet phosphors but also pave a definitive route towards understanding the fundamental mechanisms responsible for the NIR emission of Mn^(2+)ions.展开更多
基金supported by funds from the National Transgenic Major Program Grants(No.2009ZX08009-022B)
文摘Rice is one of the most consumed staple food plants around the world, and its plant architecture is very important to improve the grain yield （Zhang et al., 2008）. Plant height, leaf angle, tiller number and angle, and uniformity of panicle layer all can have strong effects on grain yield （Wang and Li, 2008）. During the long history of domestication, rice has been selected to develop uniform tiller height architecture that ensures panicle layer uniformity and ease of harvesting （Ma et al., 2009）, and is largely determined by the synchronic culm elongation.
基金This project is supported by National Natural Science Foundation ofChina(No.l9832020) and National Outstanding Youth Science Foundation ofChina(No.10125208).
文摘A physical value mapping （PVM） algorithm based on finite element mesh from the stamped part in stamping process to the product is presented, In order to improve the efficiency of the PVM algorithm, a search way from the mesh of the product to the mesh of the stamped part will be adopted. At the same time, the search process is divided into two steps： entire search （ES） and local search （LS）, which improve the searching efficiency. The searching area is enlarged to avoid missing projection elements in ES process. An arc-length method is introduced in LS process. The validity is confirmed by the results of the complex industry-forming product.
基金supported by National Natural Science Foundation of China(Grant No.50675049)
文摘Micro electrical discharge machining（EDM） deposition process is a new micro machining method for fabrication of metal micro structures. In this process, the high level of tool electrode wear is used to achieve the metal material deposition. Up to now, the studies of micro EDM deposition process focused mainly on the researches of deposition process, namely the effects of discharge parameters in deposition process on the deposition rate or deposition quality. The research of the formation of micro structures with different discharge energy density still lacks. With proper conditions and only by the z-axis feeding in vertical direction, a novel shape of micro spiral structure can be deposited, with 0.11 mm in wire diameter, 0.20 mm in outside diameter, and 3.78 mm in height. Then some new deposition strategies including angular deposition and against the gravity deposition were also successful. In order to find the forming mechanism of the spiral structures, the numerical simulation of the transient temperature distribution on the discharge point was conducted by using the finite-element method（FEM）. The results show that there are two major factors lead to the forming of the spiral structures. One is the different material removal form of tool electrode according with the discharge energy density, the other is the influenced degree of the movement of the removed material particles in the discharge gap. The more the energy density in single discharge is, the smaller the mass of the removed material particles is, and the easier the movements of which will be changed to form an order tendency. The fine texture characteristics of the deposited micro spiral structures were analyzed by the energy spectrum analysis and the metallographic analysis. It shows that the components of the deposited material are almost the same as those of the tool electrode. Moreover the deposited material has the brass metallic luster in the longitudinal profile and has compact bonding with the base material. This research is useful to understand the micro-process of micro EDM deposition better and helpful to increase the controllability of the new EDM method for fabrication of micro structures.
基金provided by West Virginia State Coal and Energy Research Bureau (CERB)the Department of Mining Engineering,West Virginia University
文摘The flotation process is a particle-hydrophobic surface-based separation technique. To improve the essential flotation steps of collision and attachment probabilities, and reduce the step of detachment probabilities between air bubbles and hydrophobic particles, a selectively designed cavitation venturi tube combined with a static mixer can be used to generate very high numbers of pico and nano bubbles in a flotation column. Fully embraced by those high numbers of tiny bubbles, hydrophobic particles readily attract the tiny bubbles to their surfaces. The results of column flotation of Pittsburgh No. 8 seam coal are obtained in a 5.08 cm ID and 162 cm height flotation column equipped with a static mixer and cavitation venturi tube, using kerosene as collector and MIBC as frother. Design of the experimental procedure is combined with a statistical two-stepwise analysis to determine the optimal operating conditions for maximum recovery at a specified grade. The effect of independent variables on the responses has been explained. Combustible material recovery of 85–90% at clean coal product of 10–11% ash is obtained from feed of 29.6% ash, with a much-reduced amount of frother and collector than that used in conventional column flotation. The column flotation process utilizing pico and nano bubbles can also be extended to the lower limit and upper limit of particle size ranges, minus 75 lm and 300–600 lm, respectively, for better recovery.
基金supported by the National Natural Science Foundation of China(Grant No.12104231,12364051,22303031)Innovation Training Program for College Students in Nanjing Forestry University(Grant No.202410298184Y)。
文摘The enduring enigma surrounding the near-infrared(NIR)emission of Mn^(2+)continues to ignite intense academic discussions.Numerous hypotheses have emerged from extensive research endeavors to explain this phenomenon,such as the formation of Mn^(2+)-Mn^(2+)ion pairs,Mn^(2+)occupying cubically coordinated sites,as well as conjectures positing the involvement of Mn3+oxidized from Mn^(2+)or defects.Despite these diverse and valuable insights,none of the hypotheses have yet achieved broad consensus.In this study,we have observed prolonged fluorescence lifetimes(~10ms)for the NIR emissions of Mn^(2+)ions,hinting at these ions occupying the high-symmetry octahedral sites inherent to the garnet lattice.This inference is supported by the corroborating results from X-ray absorption fine structure analysis and first-principles calculations.The intense crystal field of octahedral sites,similar to that of AlO6,facilitates the splitting of d-d energy levels,thereby inducing a red-shift in the emission spectrum to the NIR region due to the transition ^(4)T_(1)(4G)→ ^(6)A_(n)(6S)of isolated Mn^(2+).Our findings not only offer a plausible rationale for the NIR emission exhibited by other Mn^(2+)-activated garnet phosphors but also pave a definitive route towards understanding the fundamental mechanisms responsible for the NIR emission of Mn^(2+)ions.
