检索结果-南通市图书馆

基于铁锈红和废锂箔制备LiFePO_(4)/C正极材料的储锂性能

在线全文

学校读者我要写书评

暂无评论

化工新型材料 2024年第9期52卷 241-245页

作者：侯宏英贾彦鹏于晓华荣菊兰建昆明理工大学材料科学与工程学院昆明650093

磷酸铁锂电池的需求大、市场垄断而导致原材料价格日益高涨。以铁锈红和废锂箔为原材料,采用磷酸铁工艺制备了LiFePO_(4)/C粉末,并测试其电化学储锂性能。结果表明:LiFePO_(4)/C粉末由粒径尺寸为110~400nm的颗粒组成,在1.0C循环350圈后... 详细信息

磷酸铁锂电池的需求大、市场垄断而导致原材料价格日益高涨。以铁锈红和废锂箔为原材料,采用磷酸铁工艺制备了LiFePO_(4)/C粉末,并测试其电化学储锂性能。结果表明:LiFePO_(4)/C粉末由粒径尺寸为110~400nm的颗粒组成,在1.0C循环350圈后的可逆比容量和容量保持率分别为129.7mAh/g和98.0%,与商业LiFePO_(4)正极材料性能相当。可见,该结果降低了LiFePO 4的制备成本,有利于循环经济和可持续发展。

关键词：磷酸铁锂铁锈红废锂箔循环经济制备成本

基于Hartmann哨超声喷嘴的谐振腔结构仿真研究

在线全文

学校读者我要写书评

暂无评论

热能动力工程 2024年第3期39卷 207-214页

作者：陶嘉琪姚福锋鞠东兵刘建成中国船舶集团有限公司第七〇三研究所黑龙江哈尔滨150078

为便于用试验方法研究汽轮机除湿问题,设计了一种新型大流量、高雾化度的喷嘴,在喷嘴设计中融入类似Hartmann哨的谐振腔结构,并通过超声波效应增强对水滴的雾化效果。采用Fluent流体仿真软件,对湿蒸汽环境下不同Hartmann哨谐振腔结构尺... 详细信息

为便于用试验方法研究汽轮机除湿问题,设计了一种新型大流量、高雾化度的喷嘴,在喷嘴设计中融入类似Hartmann哨的谐振腔结构,并通过超声波效应增强对水滴的雾化效果。采用Fluent流体仿真软件,对湿蒸汽环境下不同Hartmann哨谐振腔结构尺寸的流场速度、压力脉动以及谐振频率进行数值模拟,得到最佳谐振腔结构尺寸。研究结果表明:喷嘴入口压力一定时,改变谐振腔与喷嘴出口的角度(谐振腔夹角),速度脉动会随谐振腔夹角的增大而增大,而压力脉动随谐振腔夹角增大呈先增大后减小的趋势,在125°夹角下出现峰值;125°夹角下速度脉动最大值区域及谐振频率随谐振腔直径增大而减小;最终确定谐振腔的结构参数,其夹角为125°、直径为3.4 mm、深度为6.4 mm,该结构参数下谐振频率为21 kHz,符合所需频率。

关键词： Hartmann哨谐振腔谐振频率速度脉动压力脉动

Coordinating Pricing and Inventory Control in a Fluctuating Environment

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2010年第2期26卷 187-204页

作者： ju-liang Zhang jian Chen Xiang-sun Zhang Department of Logistics Management School of Economics and Management Beijing Jiaotong UniversityBeijing 100044 China Department of Management Science and Engineering School of Economics and Management Tsinghua Uni-versity Beijing 100084 China Institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sci-ences Beijing 100190 China

This paper addresses the simultaneous determination of pricing and inventory replenishment strate- gies under a fluctuating environment. Specifically, we analyze the single item, periodic review model. The demand consists of two parts： the deterministic component, which is influenced by the price, and the stochastic component （perturbation）. The distribution of the stochastic component is determined by the current state of an exogenous Markov chain. The price that is charged in any given period can be specified dynamically. A replenishment order may be placed at the beginning of some or all of the periods, and stockouts are fully backlogged. Ordering costs that are lower semicontinuous, and inventory/backlog （or surplus） costs that are continuous with polynomial growth. Finite-horizon and infinite-horizon problems are addressed. Existence of optimal policies is established. Furthermore, optimality of （s,S,p）-type policies is proved when the ordering cost consists of fixed and proportional cost components and the surplus cost （these costs are all state-dependent） is convex.

关键词： Stochastic inventory management Markov chains pricing finite horizon infinite horizon

Mesomechanism of steel fiber reinforcement and toughening of reactive powder concrete

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2007年第6期50卷 815-832页

作者： ju Yang JIA YuDan LIU HongBin CHEN jian State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China

Reactive powder concrete (RPC) is a novel cement-based composite material with ultra-high strength. Embedding a certain amount of short steel fibers in the matrix can improve the RPC’s toughness and overcome the disadvantage of high brittle- ness. In this paper, a number of direct uniaxial tension tests have been carried out with ‘8-shape’ RPC200 specimens. The bond-slip process, mesoscopic structural variation and mechanical characteristics of a fiber pullout of the matrix have been investigated using the real-time SEM loading system and CCD observation tech- niques. The influence of the volume of embedded short steel fibers in matrix on the mesoscopic morphology of attachments on the surface of a pulled individual fiber, the initial cracking force, the ultimate pullout force, interfacial bond strength and the pullout rupture energy have been analyzed. A general formulation relating these quantities to the volume of fibers in matrix has been proposed. The components comprising the interfacial bond strength have been outlined. In addition, the con- tribution that fibers make to enhance and toughen the reactive powder concrete has been discussed. It is shown that there exists an optimal threshold of fiber volume ρv, opt =1.5% at which the bond performance of a fiber pullout of RPC be- haves best.

关键词： reactive powder concrete, steel fiber, interfacial bond strength, reinforcement and toughening, mesomechanism

Optomechanical control of stacking patterns of h-BN bilayer

在线全文

学校读者我要写书评

暂无评论

Nano Research 2019年第10期12卷 2634-2639页

作者： Haowei Xu jian Zhou Yifei Li Rafael Jaramillo ju Li Department of Nuclear Science and Engineering Massachusetts Institute of TechnologyCambridgeMA 02139USA Center for Advancing Materials Performance from the Nanoscale State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an 710049China Department of Materials Science and Engineering Massachusetts Institute of TechnologyCambridgeMA 02139USA

Few-layer two-dime nsion al(2D)materials usually have differe nt(meta)-stable stacking patterns,which have distinet electronic and optical *** spired by optical tweezers,we show that a laser with selected freque ncy can modify the gen eralized stacking-fault en ergy Iandscape of bilayer hexagonal boron nitride(BBN),by coupling to the slip-dependent dielectric ***,BBN can be reversibly and barrier-freely switched betwee n its stacking patter ns in a controllable *** simulate the dyn amics of the stacki ng transition with a simplified equati on of motion and dem on strate that it happe ns at picosec ond *** one layer of BBN has a nearly-free surface boundary condition,BBN can be locked in its metastable stacking modes for a long *** a fast,reversible and non-volatile transition makes BBN a potential media for data storage and optical phase mask.

关键词： phase change materials two-dimensional materials opto-mechanics density functional theory

A cross-layer design approach on spectrum allocation and resource scheduling in cognitive PMP networks

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

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第4期9卷 435-444页

作者： Jie CHEN Min-jian ZHAO Qiao ZHOU Shi-ju LI Department of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

We propose the spectrum allocation and resource scheduling algorithms in cognitive point to multipoint (PMP) networks with rapid changes of spectrum opportunities and present a media access control (MAC) protocol based on these algorithms. The objective of spectrum allocation is to make efficient use of the spectrum while maintaining the transceiver synchronization on frequency and time in the network. The objective of resource scheduling is to guarantee the quality of service (QoS) requirements of different kinds of connections and to minimize the total energy consumption in the network as well. By sensing only a small set of possible channels in each slot based on the state transition probability of each channel, our spectrum allocation algorithm achieves high spectrum efficiency in the network. The resource scheduling problem is divided into three sub problems and we derive optimal solutions to these problems by greedy algorithm and convex optimization. The simulation results show that our algorithm can make efficient use of the spectrum and the network resources at a cost of low computational complexity.

关键词： Cognitive point to multipoint (PMP) networks Markov process Cross-layer design Convex optimization

Efficient and selective recovery of Ni, Cu, and Co from low-nickel matte via a hydrometallurgical process

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2017年第3期24卷 249-256页

作者： Guang-ju Chen jian-ming Gao Mei Zhang Min Guo School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China

Low-nickel matte was intensively characterized, and Ni, Cu, and Co were determined to exist mainly as (Fe,Ni)9S8and FeNi3, Cu5FeS4, and (Fe,Ni)9S8and Fe3O4(in isomorphic form), respectively. The efficient and selective extraction of Ni, Cu, and Co from the low-nickel matte in an (NH4)2S2O8/NH3·H2O solution system was studied. The effects of (NH4)2S2O8and NH3·H2O concentrations, leaching time, and leaching temperature on the metal extraction efficiency were systematically investigated. During the oxidative ammonia leaching process, the metal extraction efficiencies of Ni 81.07%, Cu 93.81%, and Co 71.74% were obtained under the optimal conditions. The relatively low leaching efficiency of Ni was mainly ascribed to NiFe alloy deactivation in ammonia solution. By introducing an acid pre-leaching process into the oxidative ammonia leaching process, we achieved the high extraction efficiencies of 98.03%, 99.13%, and 85.60% for the valuable metals Ni, Cu, and Co, respectively, from the low-nickel matte. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

关键词： Ammonia Cobalt Copper Efficiency Hydrometallurgy Leaching Nickel

氢氧化钾改性玉米秸秆生物炭对水中土霉素的吸附特性及机制

在线全文

学校读者我要写书评

暂无评论

环境科学 2024年第1期45卷 594-605页

作者：刘总堂孙玉凤费正皓沙新龙温小菊钱彬彬陈建谷成刚盐城师范学院化学与环境工程学院盐城224007 盐城师范学院江苏省农业养殖污染治理与资源化工程研究中心盐城224007 中国科学院南京土壤研究所中国科学院土壤环境与污染修复重点实验室南京210008

四环素类抗生素污染治理是环境研究热点问题之一,生物炭吸附是高效去除有机污染物的重要方法.以玉米秸秆为原料制备热解生物炭(BC),通过氢氧化钾改性获得KBC,选择具有最佳吸附性能的KBC在400~600℃二次热解活化,最终制得改性玉米秸秆生... 详细信息

四环素类抗生素污染治理是环境研究热点问题之一,生物炭吸附是高效去除有机污染物的重要方法.以玉米秸秆为原料制备热解生物炭(BC),通过氢氧化钾改性获得KBC,选择具有最佳吸附性能的KBC在400~600℃二次热解活化,最终制得改性玉米秸秆生物炭AKBC400、AKBC500和AKBC600,并对其结构和表面性质进行表征.通过批处理实验,以BC400为对照,考察了3种AKBC对溶液中盐酸土霉素(OTC)的吸附动力学和吸附热力学特征.与BC400相比,AKBC比表面积增加23.0~37.6倍,孔隙结构显著改善,芳香性增强,吸附性能显著提高.准二级动力学模型可以更好地拟合AKBC对OTC的吸附过程,AKBC500对OTC的吸附速率常数和吸附量均高于AKBC400和AKBC600.颗粒内扩散和膜扩散均是AKBC吸附OTC的控速步骤.Langmuir、Freundlich和Temkin模型均可较好地拟合吸附等温线.AKBC对OTC的吸附均为自发、吸热和熵增加过程,吸附过程同时存在物理吸附和化学吸附作用.AKBC对OTC吸附机制包括孔填充、氢键、π—π共轭、阳离子—π键和强静电作用.AKBC具有良好的孔隙结构和较高的吸附容量,且再生吸附性能稳定,对去除水中土霉素具有较好的潜能.

关键词：玉米秸秆生物炭氢氧化钾改性热解活化盐酸土霉素(OTC) 吸附

数字经济发展对居民家庭消费的影响机理与效应研究

在线全文

学校读者我要写书评

暂无评论

计量经济学报 2024年第3期4卷 805-834页

作者：王瑶瑶张萌贾锐宁柴建郭菊娥军事科学院战略评估咨询中心北京100091 西安电子科技大学经济与管理学院西安710126 西安交通大学管理学院西安710049

在后疫情时代逆全球化思潮抬头的背景下,如何扩大居民消费规模和畅通经济内循环成为当下亟待解决的重要问题.数字经济与传统产业的深度融合能够创造可观的“数字红利”,是扩大内需以及实现高质量发展的关键驱动力.本文利用中国家庭追踪... 详细信息

在后疫情时代逆全球化思潮抬头的背景下,如何扩大居民消费规模和畅通经济内循环成为当下亟待解决的重要问题.数字经济与传统产业的深度融合能够创造可观的“数字红利”,是扩大内需以及实现高质量发展的关键驱动力.本文利用中国家庭追踪调查数据库(CFPS)与宏观数据相匹配,构建面板固定效应模型进行估计.研究发现:①数字经济发展能够显著提升居民家庭消费水平和居民人均消费水平,且具有稳健性.②数字经济发展主要通过改善居民收入质量对居民消费水平产生积极影响.而消费环境的优化不是数字经济提升居民家庭消费的主要原因.③异质性分析表明,数字经济发展对低失业率地区和以及低人力资本家庭的消费提升作用更为明显.④从家庭消费结构来看,数字经济发展显著提高了各类收入群体的发展型消费支出,仅对高收入家庭的享受型支出有显著的正向作用.本文的研究结论为进一步利用数字经济发展来释放消费潜力提供了决策依据.

关键词：数字经济发展居民家庭消费收入质量消费环境消费结构