检索结果-南通市图书馆

Three-mode optomechanical system for angular velocity detection

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第8期27卷 254-260页

作者： kai Li Sankar Davuluri yong Li Beijing Computational Science Research Center Beijing 100193China

We propose a scheme for measuring the angular velocity of absolute rotation using a three-mode optomechanical system in which one mode of the two-dimensional （2D） mechanical resonator is coupled to an optical cavity. When the total system rotates, the Coriolis force acting on the 2D mechanical resonator due to the absolute rotation will affect the mechanical motion and thus change the phase of the output field from the cavity. The angular velocity of the absolute rotation can be estimated by monitoring the spectrum of the output field from the cavity via homodyne measurement. The minimum measurable angular velocity, which is determined by the noise spectrum, is calculated. The working range of the gyroscope for measuring angular velocity is discussed.

关键词： optomechanics gyroscope

A novel cooperative mid-course guidance scheme for multiple intercepting missiles

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2017年第3期30卷 1140-1153页

作者： Long WANG Yu YAO Fenghua he kai LIU Control and Simulation Centre Harbin Institute of Technology School of Aeronautics and Astronautics Dalian University of Technology

In the interception engagement,if the target movement information is not accurate enough for the mid-course guidance of intercepting missiles,the interception mission may fail as a result of large handover *** paper proposes a novel cooperative mid-course guidance scheme for multiple missiles to intercept a target under the condition of large detection *** this scheme,the launch and interception moments are staggered for different *** earlier launched missiles can obtain a relatively accurate detection to the target during their terminal guidance,based on which the latter missiles are permitted to eliminate the handover error in the mid-course guidance.A significant merit of this scheme is that the available resources are fully exploited and less missiles are needed to achieve the interception *** this end,first,the design of cooperative handover parameters is formulated as an optimization ***,an algorithm based on Monte Carlo sampling and stochastic approximation is proposed to solve this optimization problem,and the convergence of the algorithm is proved as ***,simulation experiments are carried out to validate the effectiveness of the proposed cooperative scheme and algorithm.

关键词： Cooperative guidance Handover design Monte Carlo sampling Shoot-shoot-look Stochastic approximation Stochastic optimization

Co-pyrolysis characteristics and interaction route between low-rank coals and Shenhua coal direct liquefaction residue

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2019年第11期27卷 2815-2824页

作者： kai Li Xiaoxun Ma Ruiyu he Zhenni Li School of Chemical Engineering Northwest UniversityXi'an 710069China International Scientific and Technological Cooperation Base of the Ministry of Science and Technology(MOST)for Clean Utilization of Hydrocarbon Resources Xi'an 710069China Chemical Engineering Research Center of the Ministry of Education(MOE)for Advanced Use Technology of Shanbei Energy Xi'an 710069China Shaanxi Research Center of Engineering Technology for Clean Coal Conversion Xi'an 710069China Collaborative Innovation Center for Development of Energy and Chemical Industry in Northern Shaanxi Xi'an 710069China

To reasonably utilize the coal direct liquefaction residue(DLR), contrasting research on the co-pyrolysis between different low-rank coals and DLR was investigated using a TGA coupled with an FT-IR spectrophotometer and a fixed-bed reactor. GC–MS, FTIR, and XRD were used to explore the reaction mechanisms of the various co-pyrolysis processes. Based on the TGA results, it was confirmed that the tetrahydrofuran insoluble fraction of DLR helped to catalyze the conversion reaction of lignite. Also, the addition of DLR improved the yield of tar in the fixed-bed, with altering the composition of the tar. Moreover, a kinetic analysis during the co-pyrolysis was conducted using a distributed activation energy model. The co-pyrolysis reactions showed an approximate double-Gaussian distribution.

关键词： Low-rank coal Coal direct liquefaction residue Co-pyrolysis Kinetics

Degradation of refractory pollutants by hydrodynamic cavitation: Key parameters to degradation rates

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2019年第4期31卷 848-856页

作者： Zhi-yong Dong kai Zhang Rui-hao Yao College of Civil Engineering and Architecture Zhejiang University of Technology Hangzhou 310023 China

Degradations of refractory pollutants by hydrodynamic cavitation were experimentally carried out in a self-developed hydrodynamic cavitation reactor with Venturi tubes, multi-orifice plates and their combinations. Effects of hydraulic elements of cavitation due to the Venturi tube on degradation of refractory hydrophobic pollutant were studied, and an optimal throat length corresponding to the maximum degradation rate was obtained. Effects of cavitation due to number, size and distribution of orifice for the multi-orifice plates on degradation of refractory hydrophilic pollutant were investigated, and comparisons and analyses were made. Effects of cavitation due to different combinations of the Venturi tubes with the triangular multi-orifice plates on degradation of hydrophilic and hydrophobic mixtures were studied, and an appropriate combination was determined. Also, effects of cavitation duration, pH value and initial concentration on the refractory pollutants were explored.

关键词： Hydrodynamic cavitation Venturi tube multi-orifice plate refractory pollutant combination effect

Theoretical investigations of transport properties of organic solvents in cation-functionalized graphene oxide membranes： Implications for drug delivery

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2018年第1期11卷 254-263页

作者： kai Song yong Long Xun Wang Gang Zhou State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology Beijing 100029 China Key Lab of Organic Optoelectronics and Molecular Engineering Department of Chemistry Tsinghua University Beijing 100084 China

We perform detailed quantum chemical calculations to elucidate the origin and mechanism of the selective permeability of alkali and alkaline earth cation- decorated graphene oxide （M-GO） membranes to organic solvents. The results show that the selectivity is associated mainly with the transport properties of solvents in the membranes, which depends on two regions of the flow path： the sp3 C-O matrix of the GO sheets and the cation at the center of the hexagon rather than the sp~ region. According to the delocalization of ~ states in sp2 regions, we propose a design guide for high-quality M-GO membranes. The solvent-cation interaction essentially causes directional transport of molecules in the M-GO membranes under the transmembrane pressure, indicating a site-to-site mech- anism. The solvent-sp3 C-O matrix interaction may inhibit molecular transport between two fixed cations by consuming energy. The competition between energy consumption by the solvent-cation interaction and energy expenditure by the solvent-sp3 C-O matrix interaction leads to various transport properties of solvents and thus allows for the selective permeability of the M-GO membranes. Findings from the study are helpful for the future design of multifunctional M-GO macro-membranes as cost-effective solution nanofilters in chemical, biological, and medical applications

关键词： alkali and alkaline earthcation-decorated grapheneoxide (M-GO) membrane organic solvent permeability transport density functional theory

High-entropy intermetallics:from alloy design to structural and functional properties

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2022年第6期41卷 1989-2001页

作者： Hang Wang Quan-Feng he yong Yang Department of Mechanical Engineering City University of Hong KongHong Kong 999077China Department of Materials Science and Engineering.City University of Hong Kong Hong Kong 999077China Department of Advanced Design and System Engineering.City University of Hong Kong Hong Kong 999077China

Conventional intermetallics are strong but ***,multi-principal element intermetallics,also termed as high-entropy intermetallics(heIs)in the recent high-entropy alloy literature,are strong but malleable,some of which even show appreciable ductility and fracture toughness at room *** this article,we provide a focused review on the recent researches on heIs,from the fundamentals,such as the concept of heIs,the formation rules to the structural and functional properties of *** results hitherto reported clearly show that the heIs with distinct properties could be a promising material for future structural and functional applications.

关键词： Internetallics High-entropy alloys Phase formation Mechanical properties Functional properies

Divergent synthesis of chiral amines via Ni-catalyzed chemo-and enantioselective hydrogenation of alkynone imines

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2023年第11期66卷 3186-3192页

作者： Yuchuan Ma kai Liu Lin he Hui Lv Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan School of Chemistry and Chemical EngineeringShihezi UniversityShihezi 832000China Hubei Key Lab on Organic and Polymeric Optoelectronic Materials Engineering Research Center of Organosilicon Compounds&MaterialsMinistry of EducationSauvage Center for Molecular SciencesKey Laboratory of Biomedical Polymers of Ministry of Education&College of Chemistry and Molecular SciencesWuhan UniversityWuhan 430072China

Ligand-mediated nickel-catalyzed asymmetric hydrogenation of alkynone imines has been achieved. By using Ni(OAc)_2·4H_2O/(S,S)-Ph-BPE complex as a catalyst, the chemo-and enantioselective hydrogenation of alkynone imines occurred efficiently to afford chiral propargyl amines with high yields and excellent enantioselectivities(up to 99% yield, >99% ee), leaving the readily reducible alkynyl group intact. Both the C=N and C≡C bonds of alkynone imines were hydrogenated efficiently in the presence of Ni(OAc)_2·4H_2O and Josiphos SL-J011-1, furnishing unfunctionalized chiral imines efficiently(up to 99% yield, >99% ee).The(Z)-allylamines and(E)-allylamines were also efficiently prepared from alkynone imines by the combination of the different catalytic systems. The preliminary mechanism study revealed that the reduction of alkynone imines was a stepwise process and the C=N bonds were preferably hydrogenated in the complete reduction of alkynone imines. The synthetic utility of this method was demonstrated by its application in the late-stage modification of the antiviral drug Zidovudine and the concise synthesis of chiral dibenzoazepine.

关键词： alkynone imine asymmetric hydrogenation propargyl amine enantioselectivity chiral amine

Instance-Specific Algorithm Selection via Multi-Output Learning

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2017年第2期22卷 210-217页

作者： kai Chen yong Dou Qi Lv Zhengfa Liang the National Laboratory for Parallel and Distributed Processing National University of Defense TechnologyChangsha 410037China the College of Computer National University of Defense TechnologyChangsha 410037China

Instance-specific algorithm selection technologies have been successfully used in many research fields,such as constraint satisfaction and planning. Researchers have been increasingly trying to model the potential relations between different candidate algorithms for the algorithm selection. In this study, we propose an instancespecific algorithm selection method based on multi-output learning, which can manage these relations more *** kinds of multi-output learning methods are used to predict the performances of the candidate algorithms：（1）multi-output regressor stacking;（2） multi-output extremely randomized trees; and（3） hybrid single-output and multioutput trees. The experimental results obtained using 11 SAT datasets and 5 Max SAT datasets indicate that our proposed methods can obtain a better performance over the state-of-the-art algorithm selection methods.

关键词： algorithm selection multi-output learning extremely randomized trees performance prediction constraint satisfaction

在线全文

学校读者我要写书评

暂无评论

荒漠灌丛对生物土壤结皮下土壤养分的影响

水土保持研究 2025年第2期32卷 83-90页

作者：安乐何静刘艳梅索凯赵紫娟王凯亮甘肃农业大学林学院兰州730000 甘肃林业职业技术大学甘肃天水741020 天水师范学院甘肃天水741000 中国科学院寒区旱区环境与工程研究所兰州730000

[目的]揭示荒漠灌丛对生物土壤结皮下土壤养分的影响,为干旱沙区荒漠生态系统的修复与管理提供理论基础和科学依据。[方法]采集腾格里沙漠东南缘红卫天然植被区的无灌丛生物土壤结皮(对照地)和白滨藜、柠条、狭叶锦鸡儿、油蒿4种典型灌... 详细信息

[目的]揭示荒漠灌丛对生物土壤结皮下土壤养分的影响,为干旱沙区荒漠生态系统的修复与管理提供理论基础和科学依据。[方法]采集腾格里沙漠东南缘红卫天然植被区的无灌丛生物土壤结皮(对照地)和白滨藜、柠条、狭叶锦鸡儿、油蒿4种典型灌丛+生物土壤结皮下0—10 cm,10—20 cm和20—30 cm土样,分别测定土壤有机质(SOM)、含水量(SWC)、pH值、全氮(TN)、速效氮(AN)、全磷(TP)、速效磷(AP)、全钾(TK)、速效钾(AK)的含量,通过土壤养分变化表征灌丛与生物土壤结皮互作对荒漠区土壤质量的影响。[结果](1)相较于对照地,灌丛与生物土壤结皮互作影响土壤养分,提高土壤TN,TK,AK,AN,SOM,AP和藻-地衣结皮TP含量,降低藓类结皮TP含量。(2)土层深度变化、灌丛和结皮类型对土壤养分有显著影响,每二者交互都对TP影响不显著,三者间交互除AN和AP外,对其余养分指标都有显著影响(p<0.05)。(3)同土层灌丛+藓类结皮下土壤TN,TP,AK,SOM的含量高于灌丛+藻-地衣结皮。(4)4种灌丛+生物土壤结皮下土壤养分富集于0—10 cm土层,表聚效应明显,灌丛、生物土壤结皮和土层深度三者间互作对土壤养分的富集能力有差异性。[结论]灌丛与生物土壤结皮互作能增加土壤肥力,改良土壤质量,对维持稳定的荒漠生态系统有重要作用。

关键词：荒漠灌丛生物土壤结皮土壤养分