提出了一种LS-RAID(Logic-level Striping Redundant Array of Independent Disks)固态盘(Solid State Disk,SSD)设计模型。在单个闪存芯片内,该模型在逻辑层实现了条带化,并将校验信息按照RAID5机制分配到逻辑闪存芯片中,从而提高了固...提出了一种LS-RAID(Logic-level Striping Redundant Array of Independent Disks)固态盘(Solid State Disk,SSD)设计模型。在单个闪存芯片内,该模型在逻辑层实现了条带化,并将校验信息按照RAID5机制分配到逻辑闪存芯片中,从而提高了固态盘可靠性。使用DiskSim进行仿真测试,表明该模型在提高可靠性的同时,对固态盘平均寿命和损耗均衡影响不大,具有实用价值。展开更多
Dealloyed ribbons with a layer of networked nanoporous structure of different pore sizes were fabricated by dealloying the as-spun Mg_(65)Cu_(25-x)Ag_(x)Y_(10)(x=0,5,10,at.%)ribbons in dilute H_(2)SO_(4) solution in o...Dealloyed ribbons with a layer of networked nanoporous structure of different pore sizes were fabricated by dealloying the as-spun Mg_(65)Cu_(25-x)Ag_(x)Y_(10)(x=0,5,10,at.%)ribbons in dilute H_(2)SO_(4) solution in order to enhance the degradation efficiency of pesticide wastewater.Compared to the as-spun ribbons,it is found that the dealloyed ribbons with the networked nanoporous structure exhibit higher degradation efficiency due to their large specific surface areas and enough active sites for the degradation process.Both the average pore sizes of the nanoporous structure and the degradation efficiency of the pesticide wastewater increase with the increase of Ag addition in the dealloyed ribbons.The maximum degradation efficiency up to 95.8%is obtained for the Mg_(65)Cu_(15)Ag_(10)Y_(10)dealloyed ribbon under the optimal conditions of pH being 3,the initial cis-cypermethrin concentration being 500 mg/L,and the dosage of dealloyed ribbon being 1.33 g/L.展开更多
We explore the electronic and transport properties of zigzag graphene nanoribbons （GNRs） with nitrogen-vacancy defects by performing fully self-consistent spin-polarized density functional theory calculations combin...We explore the electronic and transport properties of zigzag graphene nanoribbons （GNRs） with nitrogen-vacancy defects by performing fully self-consistent spin-polarized density functional theory calculations combined with non-equilibrium Green＇s function technique. We observe robust negative di erential resistance （NDR） effect in all examined molecular junctions. Through analyzing the calculated electronic structures and the bias-dependent transmission coefficients, we find that the narrow density of states of electrodes and the bias-dependent effective coupling between the central molecular orbitals and the electrode subbands are responsible for the observed NDR phenomenon. In addition, the obvious di erence of the transmission spectra of two spin channels is observed in some bias ranges, which leads to the near perfect spin-filtering effect. These theoretical findings imply that GNRs with nitrogenvacancy defects hold great potential for building molecular devices.展开更多
In China, most Precambrian banded iron formations （BIFs） are situated in the North China Craton. The Yuanjiacun iron depos- it, located in the Ltlliang area, is arguably the most representative Superior-type BIF. Th...In China, most Precambrian banded iron formations （BIFs） are situated in the North China Craton. The Yuanjiacun iron depos- it, located in the Ltlliang area, is arguably the most representative Superior-type BIF. This iron deposit is coherent with the sedimentary rock succession of the Yuanjiacun Formation in the lower Lliliang Group, and was interpreted to be deposited at 2.3-2.1 Ga, based on ages of overlying and underlying volcanic strata. This age overlaps with the time range of the Great Oxidation Event （GOE, 2.4-2.2 Ga）. The Yuanjiacun BIF consists mainly of subhedral-xenomorphic magnetite and quartz and rarely other minerals with a lower degree of metamorphism, from greenschist to lower amphibolite facies. The geochemical characteristics of this BIF are similar to those of Superior-type BIFs. Prominent positive La, Y, and Eu anomalies normalized by the Post Archean Australian Shale （PAAS） indicate that the primary chemical precipitate is a result of solutions that repre- sent mixtures of seawater and high-T hydrothermal fluids. The contamination from crustal detritus found is negligible based on low abundances of Al2O3 and TiO2 （〈0.5%） and of trace elements such as Th, Hf, Zr, and Sc （〈1.5 ppm）, as well as the lack of co-variations between Al2O3 and TiO2. In particular, the Yuanjiacun BIF samples do not display significant negative Ce anom- alies like those of the Archean iron formations, but rather, the Yuanjiacun BIF samples exhibit prominent positive Ce anoma- lies, low Y/Ho ratios, and high light to heavy REE （（Pr/Yb）sN） ratios, which are essentially consistent with the late Paleoprote- rozoic （〈2.0 Ga） BIFs around the world. These characteristics of the Yuanjiacun BIF samples imply that the ancient ocean （2.3-2.1 Ga） was redox-stratified from oxic shallow water to deeper anoxic water. The specific redox conditions of the ancient ocean may be related to the GOE, which gave rise to the oxidation of Ce and Mn in the upper water, and to the presence of a Mn oxide shuttle in the ocean, resulting in varying REE patterns due to the precipitation and dissolution of this Mn oxide shut tle under different redox states. Therefore, the Yuanjiacun BIF appears to have formed near the redoxcline and lower-level reduced marine water.展开更多
An optimization model is constructed to formulate the maximization problem on the capacity of V-belt drive. The concavity,the monotonicity and the global optimality condition are studied for the objective function,and...An optimization model is constructed to formulate the maximization problem on the capacity of V-belt drive. The concavity,the monotonicity and the global optimality condition are studied for the objective function,and it is proved that the feasible region of the model is bounded,closed and convex under some design conditions. Then,a solution method,called an optimal segment algorithm,is developed to find the global maximizer of the model. Under four different design conditions,solution methods are presented respectively. Some real case studies are employed to demonstrate that the model and the algorithm in this paper are promising.展开更多
文摘提出了一种LS-RAID(Logic-level Striping Redundant Array of Independent Disks)固态盘(Solid State Disk,SSD)设计模型。在单个闪存芯片内,该模型在逻辑层实现了条带化,并将校验信息按照RAID5机制分配到逻辑闪存芯片中,从而提高了固态盘可靠性。使用DiskSim进行仿真测试,表明该模型在提高可靠性的同时,对固态盘平均寿命和损耗均衡影响不大,具有实用价值。
基金the financial supports from State Key Laboratory of Light Alloy Casting Technology for High-end Equipmentthe Natural Science Foundation of Liaoning Province,China(No.2020-KF-14-03)the National Natural Science Foundation of China(No.51775353)。
文摘Dealloyed ribbons with a layer of networked nanoporous structure of different pore sizes were fabricated by dealloying the as-spun Mg_(65)Cu_(25-x)Ag_(x)Y_(10)(x=0,5,10,at.%)ribbons in dilute H_(2)SO_(4) solution in order to enhance the degradation efficiency of pesticide wastewater.Compared to the as-spun ribbons,it is found that the dealloyed ribbons with the networked nanoporous structure exhibit higher degradation efficiency due to their large specific surface areas and enough active sites for the degradation process.Both the average pore sizes of the nanoporous structure and the degradation efficiency of the pesticide wastewater increase with the increase of Ag addition in the dealloyed ribbons.The maximum degradation efficiency up to 95.8%is obtained for the Mg_(65)Cu_(15)Ag_(10)Y_(10)dealloyed ribbon under the optimal conditions of pH being 3,the initial cis-cypermethrin concentration being 500 mg/L,and the dosage of dealloyed ribbon being 1.33 g/L.
基金This work was partially supported by the National Natural Science Foundation of China （No.20903003 and No.21273208）, the Anhui Provincial Natural Science Foundation （No.1408085QB26）, the China Postdoctoral Science Foundation （No.2012M511409）, the Supercomputer Center of Chinese Academy of Sciences, and University of Science and Technology of China and Shanghai Supercomputer Centers.
文摘We explore the electronic and transport properties of zigzag graphene nanoribbons （GNRs） with nitrogen-vacancy defects by performing fully self-consistent spin-polarized density functional theory calculations combined with non-equilibrium Green＇s function technique. We observe robust negative di erential resistance （NDR） effect in all examined molecular junctions. Through analyzing the calculated electronic structures and the bias-dependent transmission coefficients, we find that the narrow density of states of electrodes and the bias-dependent effective coupling between the central molecular orbitals and the electrode subbands are responsible for the observed NDR phenomenon. In addition, the obvious di erence of the transmission spectra of two spin channels is observed in some bias ranges, which leads to the near perfect spin-filtering effect. These theoretical findings imply that GNRs with nitrogenvacancy defects hold great potential for building molecular devices.
基金supported by the Major State Basic Research Programme of the People’s Republic of China(Grant No.2012CB416601)the Knowledge Innovation Programme of the Chinese Academy of Sciences(Grant No.KZCX2-YW-Q04-07)
文摘In China, most Precambrian banded iron formations （BIFs） are situated in the North China Craton. The Yuanjiacun iron depos- it, located in the Ltlliang area, is arguably the most representative Superior-type BIF. This iron deposit is coherent with the sedimentary rock succession of the Yuanjiacun Formation in the lower Lliliang Group, and was interpreted to be deposited at 2.3-2.1 Ga, based on ages of overlying and underlying volcanic strata. This age overlaps with the time range of the Great Oxidation Event （GOE, 2.4-2.2 Ga）. The Yuanjiacun BIF consists mainly of subhedral-xenomorphic magnetite and quartz and rarely other minerals with a lower degree of metamorphism, from greenschist to lower amphibolite facies. The geochemical characteristics of this BIF are similar to those of Superior-type BIFs. Prominent positive La, Y, and Eu anomalies normalized by the Post Archean Australian Shale （PAAS） indicate that the primary chemical precipitate is a result of solutions that repre- sent mixtures of seawater and high-T hydrothermal fluids. The contamination from crustal detritus found is negligible based on low abundances of Al2O3 and TiO2 （〈0.5%） and of trace elements such as Th, Hf, Zr, and Sc （〈1.5 ppm）, as well as the lack of co-variations between Al2O3 and TiO2. In particular, the Yuanjiacun BIF samples do not display significant negative Ce anom- alies like those of the Archean iron formations, but rather, the Yuanjiacun BIF samples exhibit prominent positive Ce anoma- lies, low Y/Ho ratios, and high light to heavy REE （（Pr/Yb）sN） ratios, which are essentially consistent with the late Paleoprote- rozoic （〈2.0 Ga） BIFs around the world. These characteristics of the Yuanjiacun BIF samples imply that the ancient ocean （2.3-2.1 Ga） was redox-stratified from oxic shallow water to deeper anoxic water. The specific redox conditions of the ancient ocean may be related to the GOE, which gave rise to the oxidation of Ce and Mn in the upper water, and to the presence of a Mn oxide shuttle in the ocean, resulting in varying REE patterns due to the precipitation and dissolution of this Mn oxide shut tle under different redox states. Therefore, the Yuanjiacun BIF appears to have formed near the redoxcline and lower-level reduced marine water.
基金supported by the National Natural Science Foundation of China (Grant Nos.71071162,70921001)the project for Excellent Talent of New Century,Ministry of Education of China (Grant No.NCET-07-0864)
文摘An optimization model is constructed to formulate the maximization problem on the capacity of V-belt drive. The concavity,the monotonicity and the global optimality condition are studied for the objective function,and it is proved that the feasible region of the model is bounded,closed and convex under some design conditions. Then,a solution method,called an optimal segment algorithm,is developed to find the global maximizer of the model. Under four different design conditions,solution methods are presented respectively. Some real case studies are employed to demonstrate that the model and the algorithm in this paper are promising.
