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Study on Characteristics of Underground Horizontal Electric Field Caused by Lightning Return Stroke Based on FDTD Method 预览
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作者 Zhao Liang Gu Lili +1 位作者 Hao Ling Liu Ruixiang 《气象与环境研究:英文版》 CAS 2019年第1期39-42,共4页
Based on the MTLL lightning return stroke model, a two-dimensional cylindrical finite-difference time-domain (FDTD) model for underground horizontal electric field was established, and the effects of distance from lig... Based on the MTLL lightning return stroke model, a two-dimensional cylindrical finite-difference time-domain (FDTD) model for underground horizontal electric field was established, and the effects of distance from lightning channel, depth, soil electrical conductivity and its distribution, and return stroke current on the characteristics of underground horizontal electric field were analyzed. The results showed that as long as the electrical conductivity of soil existed, the peak of underground horizontal electric field decreased with the increase in the horizontal distance from lightning channel. When the electrical conductivity of the upper soil was much smaller than that of the lower soil, the peak of corresponding horizontal electric field was larger than the electric field peak as the electrical conductivity of the upper soil was larger than that of the lower soil. When the electrical conductivity of the upper soil was less than that of the lower soil, the growth and decay of the horizontal electric field were faster than the growth and decay as the electrical conductivity of the upper soil was larger than that of the lower soil. 展开更多
关键词 UNDERGROUND HORIZONTAL electric field LIGHTNING RETURN stroke FDTD Single layer soil LAYERED
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Influence of Reaction Time on Growth Behaviours of Mg-Al LDH Films 预览
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作者 WU Liang CHEN Jing +5 位作者 ZHANG Sheng TANG Ai-tao YANG Dan-ni ZHANG Gen LIU Lei PAN Fu-sheng 《表面技术》 EI CAS CSCD 北大核心 2019年第3期19-26,共8页
Mg-Al LDH film was fabricated on anodized magnesium alloy AZ31 by in-situ growth method.The characteristics of the film were investigated by X-ray diffraction(XRD),Fourier transform infrared(FT-IR),scanning electron m... Mg-Al LDH film was fabricated on anodized magnesium alloy AZ31 by in-situ growth method.The characteristics of the film were investigated by X-ray diffraction(XRD),Fourier transform infrared(FT-IR),scanning electron microscopy(SEM)observation and electrochemical tests.The results showed that the crystallinity of LDH film was increased with reaction time.When the reaction time was more than 12 h,the LDH film had complete crystal layered structure.The anodic oxide film was sealed basically by the growth of LDH nanosheets after 6 h reaction.The corrosion resistance of the films became better with the increasing of reaction time.However,after 12 h reaction,the corrosion resistance of the film decreased.The formation behavior of the Mg-Al LDH film was proposed.That the competitive growth of LDH grains,which contains dissolution and recrystallization,was proposed to explain the change of the growth and corrosion resistance of the Mg-Al LDH film. 展开更多
关键词 magnesium alloy corrosion resistance in-situ GROWTH LAYERED double hydroxide(LDH) reaction time
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Numerical simulation and experimental study on dissolving characteristics of layered salt rocks
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作者 Qiqi Wanyan Yiming Xiao Na Tang 《中国化学工程学报:英文版》 SCIE EI CAS CSCD 2019年第5期1030-1036,共7页
Underground salt cavern reservoirs are ideal spaces for energy storage. China is rich in salt rock resources with layered lacustrine sedimentary structures. However, the dissolution mechanism of layered salt rocks rem... Underground salt cavern reservoirs are ideal spaces for energy storage. China is rich in salt rock resources with layered lacustrine sedimentary structures. However, the dissolution mechanism of layered salt rocks remains poorly understood, resulting in significant differences between the actual measurements and the designed indices for the layered salt rock water-soluble cavity-making cycle and the cavity shape. In this work, the dissolution rates of 600 groups of layered salt rocks in China under different conditions were determined experimentally.Thus, the established artificial neural network prediction model was used to assess the effects of the contents of NaCl, Na2 SO4, and CaSO4 in the salt rocks, concentrations, dissolution angles, and flow rates on their dissolution rates by performing ANOVA and F-test. The results provide a theoretical basis for evaluating the dissolution rate of layered salt rocks under different conditions and for the numerical simulation of the layered salt rock water-soluble cavity-making process. 展开更多
关键词 SALT CAVERN RESERVOIRS LAYERED SALT rock DISSOLUTION rate ANOVA
模板法合成层状钛硅分子筛的表征及稳定性能 预览
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作者 赵大洲 《石油化工》 CAS CSCD 北大核心 2019年第5期461-465,共5页
]在碱性环境下,采用四丙基氢氧化铵模板剂,以正硅酸乙酯和钛酸四丁酯分别作为硅源和钛源,通过模板法合成钛硅分子筛,利用XRD,SEM,TEM 等分析方法对制备的钛硅分子筛进行表征,并对不同酸碱条件下及经不同温度处理后钛硅分子筛试样层状结... ]在碱性环境下,采用四丙基氢氧化铵模板剂,以正硅酸乙酯和钛酸四丁酯分别作为硅源和钛源,通过模板法合成钛硅分子筛,利用XRD,SEM,TEM 等分析方法对制备的钛硅分子筛进行表征,并对不同酸碱条件下及经不同温度处理后钛硅分子筛试样层状结构的稳定性进行考察。实验结果表明,所制备的钛硅分子筛试样具有有序的层状结构,在稀碱溶液或中性溶液中,层状结构相对稳定,在酸性环境中,层状结构不稳定,容易被破坏;在室温下,层状结构相对稳定,在高温或低温下,层状结构稳定性较差。 展开更多
关键词 模板法 钛硅分子筛 层状 稳定性能
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A new Tin-based O3-Na0.9[Ni0.45-x/2MnxSn0.55-x/2]O2 as sodium-ion battery cathode 预览
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作者 Xiaohui Rong Xingguo Qi +8 位作者 Yaxiang Lu Yuesheng Wang Yunming Li Liwei Jiang Kai Yang Fei Gao Xuejie Huang Liquan Chen Yong-Sheng Hu 《能源化学:英文版》 SCIE EI CAS CSCD 2019年第4期132-137,共6页
Recently,sodium-ion batteries (SIBs),regarded as promising supplements for lithium-ion batteries (LIBs),especially in the large-scale energy storage field,are attracting more and more attention.However,the limited sui... Recently,sodium-ion batteries (SIBs),regarded as promising supplements for lithium-ion batteries (LIBs),especially in the large-scale energy storage field,are attracting more and more attention.However,the limited suitable cathode materials hinder the wide commercialization of SIBs.Given this aspect,in this work,a new layered oxide with 4d metal Tin was synthesized and investigated as cathode material for SIBs.Two optimized sodium-deficient 03-Na0.9Ni0.45Sn0.55O2 and O3-Nd0.9Ni0.4Mn0.1Sn0.5O2 were selected for comprehensive investigation,both of which exhibited high operating voltage of around 3.45 V with smooth charge/discharge curves.In comparison,O3-Na0.9Ni0.4Mn0.1Sn0.5O2 shows a higher reversible capacity (65 mAh/g,0.1 C),better rate capability and cycling stability than that of O3-Na0.9Ni0.45Sn0.55O2 (50mAh/g,0.1C),indicating that a small amount: of Mn-substitution can improve the electrochemical performa nee.This work presents a new possibility of discoven ng potential cathode candidates by exploring the Tin-based layered oxides. 展开更多
关键词 Sodium-ion batteries Layered oxide CATHODE Tin-based CATHODE
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Selective removal of heavy metal ions in aqueous solutions by sulfide-selector intercalated layered double hydroxide adsorbent
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作者 Jing Wang Liang Zhang +5 位作者 Tianshu Zhang Ting Du Tao Li Tianli Yue Zhonghong Li Jianlong Wang 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第9期1809-1816,共8页
Remaining largely under-appreciated, a majority of metal ion sorbents are limited in their target selectivity. In this work, a 3D sulfide intercalated NiFe-layered double hydroxide (NFL-S) hierarchical sorbent has bee... Remaining largely under-appreciated, a majority of metal ion sorbents are limited in their target selectivity. In this work, a 3D sulfide intercalated NiFe-layered double hydroxide (NFL-S) hierarchical sorbent has been synthesized for selective heavy metal removal. The intercalation of sulfurated groups in the interlayer of the layered double hydroxide (LDH) nanosheets endows NFL-S as a selective heavy metal ion filter;the selectivity of NFL-S for heavy metals is in the order of Pb^2+> Cu^2+≥ Zn^2+> Cd^2+> Mn^2+, and NFL-S has high kd values for Pb2+(~10^6 mL/g) and Cu2+(~10^5 mL/g). Scanning electron microscopy. X-ray photoelectron spectroscopy and powder X-ray diffraction were used to analyze the composition of the as-prepared nanoadsorbent. The selective adsorption behavior was systematically studied using batch experiments, and the performance was evaluated through kinetic and isotherm studies. Moreover, the adsorption mechanism of heavy metals by NFL-S through surface complexation was also investigated, which shows great potential for water decontamination. 展开更多
关键词 Layered double hydroxide nanosheets SULFIDE SELECTIVE adsorption Heavy metal IONS
Unique NiFe–NiCoO2 hollow polyhedron as bifunctional electrocatalysts for water splitting 预览
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作者 Rong Shi Jiaxin Wang +2 位作者 Zhi Wang Tengfei Li Yu-Fei Song 《能源化学:英文版》 SCIE EI CAS CSCD 2019年第6期74-80,共7页
It is of significance to design of stable and cost-effective electrocatalyst for water splitting with high efficiency in an alkaline medium.The major obstacles for practical application of water splitting devices are ... It is of significance to design of stable and cost-effective electrocatalyst for water splitting with high efficiency in an alkaline medium.The major obstacles for practical application of water splitting devices are lack of high-efficiency and low-cost electrocatalysts with low overpotential for both HER and OER.In this paper,we report a NiFe alloy decorated NiCoO2 hollow polyhedron(denoted as Ni Fe–Ni Co O2)by using[NiFe(CN)6]- intercalated NiCo–LDH as precursor.As evidenced by the electrochemical active surface area,the resultant Ni Fe–Ni Co O2 composite shows unique hollow nanostructure,which can not only provide abundant mass transport channels,but also increase the contact area of the NiFe–Ni Co O2 material with the electrolyte.The overpotential(η)demand is 286 mV for OER and 102 mV for HER at the current density of 10 mA/cm2 in an alkaline medium of 1 M KOH for the NiFe/NiCoO2 composite.This work provides a new pathway for preparation of the highly efficient bifunctional electrocatalysts for water splitting. 展开更多
关键词 Layered double HYDROXIDES (LDHs) HOLLOW POLYHEDRON Water splitting
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Intercalation assembly of kojic acid into Zn-Ti layered double hydroxide with antibacterial and whitening performances
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作者 Xin-Rui Wang Hui-Min Cheng +4 位作者 Xue-Wei Gao Wei Zhou Shu-Jing Li Xue-Li Cao Dongpeng Yan 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第4期919-923,共5页
A melanin synthesis inhibitor and bacteriostatic agent, kojic acid (KA) has been intercalated into Zn-Ti layered double hydroxide (LDH) by an anion-exchange reaction. The structure and the thermal stability of the sam... A melanin synthesis inhibitor and bacteriostatic agent, kojic acid (KA) has been intercalated into Zn-Ti layered double hydroxide (LDH) by an anion-exchange reaction. The structure and the thermal stability of the samples were characterized by XRD, FT-IR, TG-DTA and SEM. The study of KA release from ZnTi-KALDH in phosphate buffered solution (pH 5) implies that ZnTi-KA-LDH is a better controlled release system than pure KA. Meanwhile, the mechanisms of slow release were assessed by using four commonly kinetic models. The antimicrobial activity of ZnTi-KA-LDH was tested against three kinds of bacteria. The inhibition of L-dopa oxidation was tested to verify its skin whitening effect. The studies suggest that the kojic acid intercalated LDHs has the potential application as a safely functional composite in cosmetic. 展开更多
关键词 Layered double HYDROXIDE Kojic acid INTERCALATION SLOW release ANTIMICROBIAL TYROSINASE
Lead-free thermochromic perovskites with tunable transition temperatures for smart window applications
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作者 Jingwen Li Xiaolong Liu +5 位作者 Peixin Cui Junmeng Li Tao Ye Xi Wang Chuang Zhang Yong Sheng Zhao 《中国科学:化学英文版》 SCIE EI CAS CSCD 2019年第9期1257-1262,共6页
The structural flexibility of hybrid perovskite materials allows for phase transition and consequently thermochromic properties.Here we investigate the thermochromic performance in a series of copper-based layered per... The structural flexibility of hybrid perovskite materials allows for phase transition and consequently thermochromic properties.Here we investigate the thermochromic performance in a series of copper-based layered perovskites with organic cations having different alky chain lengths. Their transition temperature is found to be dependent on the organic cations due to molecular motion and hydrogen bond interaction, providing possibilities to prepare thermochromic semiconductors near room temperature for smart window applications. 展开更多
关键词 LEAD-FREE perovskites THERMOCHROMIC transition ALKYL AMMONIUM ions LAYERED structures smart windows
A Layered Chitosan/Graphene Oxide Sponge as Reusable Adsorbent for Removal of Heavy Metal Ions
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作者 ZHANG Di LI Ning +6 位作者 CAO Shuai LIU Xi QIAO Mingwu ZHANG Pingan ZHAO Qiuyan SONG Lianjun HUANG Xianqing 《高等学校化学研究:英文版》 SCIE CAS CSCD 2019年第3期463-470,共8页
Along with the growing severity of environment problem and energy crisis, it is inevitable to develop novel materials, which are contributed to the removal of hazardous pollutants from contaminated water. Herein, we r... Along with the growing severity of environment problem and energy crisis, it is inevitable to develop novel materials, which are contributed to the removal of hazardous pollutants from contaminated water. Herein, we reported a fhcile method for the preparation of free-standing chitosan/graphene oxide(CS/GO) composite sponges with low density, where CS/GO mixtures were first synthesized by tlie homogeneous reaction of chitosan and graphene oxide in aqueous acetic acid solution;then CS/GO sponges were obtained by lyophilizing the suspension, which were prefrozen at -20 ℃ and in liquid nitrogen successively. The obtained layered sponge showed good water- driven shape memory effect and was a good adsorbent of Co^2+ and Ni^2+ witli a large adsorption capacity of 224.8 and 423.7 mg/g, respectively. Importantly, the successive adsorption-desorption studies employing CS/GO sponge indicated that the composite could be regenerated by HC1 solution and reused in more than five cycles with regeneration efficiency beyond 80%. Also, the resultant sponge was explored as an exceptionally adsorbent for the removal of organic dye(e.g., methylene blue, MB). 展开更多
关键词 Adsorption Heavy metal Graphene oxide CHITOSAN LAYERED structure
High-energy Mn-based layered cathodes for sodium-ion batteries
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作者 Shaohua Guo Haoshen Zhou 《科学通报:英文版》 SCIE EI CSCD 2019年第3期149-150,共2页
Sodium-ion batteries (SIBs) have great potential in large-scale energy storage applications due to the low cost and abundance of sodium resources (1,2)However, some critical issues, such as low energy density and infe... Sodium-ion batteries (SIBs) have great potential in large-scale energy storage applications due to the low cost and abundance of sodium resources (1,2)However, some critical issues, such as low energy density and inferior cycling performance, definitely hinder the practical application of SIBs, in part because of the bigger and heavier Na ion in contrast with the Li ion as an energy carrier (3)Recently, a surge of attention has been paid to the Mnbased materials due to the earth abundant and environmentally friendly manganese element [4,5]. 展开更多
关键词 Mn HIGH-ENERGY Mn-based LAYERED cathodes for sodium-ion batteries
A field-effect approach to directly profiling the localized states in monolayer MoS2
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作者 Hao Wu Yuan Liu +10 位作者 Zeyu Deng Hung-Chieh Cheng Dehui Li Jian Guo Qiyuan He Sen Yang Mengning Ding Yun-Chiao Huang Chen Wang Yu Huang Xiangfeng Duan 《科学通报:英文版》 SCIE EI CSCD 2019年第15期1049-1055,共7页
A fundamental understanding of the charge transport mechanism in two-dimensional semiconductors(e.g., MoS2) is crucial for fully exploring their potential in electronic and optoelectronic devices. By using monolayer g... A fundamental understanding of the charge transport mechanism in two-dimensional semiconductors(e.g., MoS2) is crucial for fully exploring their potential in electronic and optoelectronic devices. By using monolayer graphene as the barrier-free contact to MoS2, we show that the field-modulated conductivity can be used to probe the electronic structure of the localized states. A series of regularly distributed plateaus were observed in the gate-dependent transfer curves. Calculations based on the variable-range hopping theory indicate that such plateaus can be attributed to the discrete localized states near mobility edge. This method provides an effective approach to directly profiling the localized states in conduction channel with an ultrahigh resolution up to 1 meV. 展开更多
关键词 Two-dimensional LAYERED materials FIELD-EFFECT transistor LOCALIZED STATES Electronic transport Conductivity plateau
Impact of layered soil structure on integration and revolution Processes 预览
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作者 Hen Li 《探索-土壤科学》 2019年第1期20-22,共3页
Soil depth profile structure has great impact. rainfall infiltration, erosion processes. A laboratoryExperiment. carried out. simulate infiltration, erosion Processes. different Layered soils,. explore. impact. layere... Soil depth profile structure has great impact. rainfall infiltration, erosion processes. A laboratoryExperiment. carried out. simulate infiltration, erosion Processes. different Layered soils,. explore. impact. layered structures. infiltration runoff, water erosion processes.: showed, runoff time decreased while runoff , intensity. soil erosion increased. increasing rainfall intensity. layered soils. top sand layer, bottom clay layer had higher stable infiltration rate under a given rainfall intensity, Soil erosion. reduced. layered soils. top clay layer, bottom sand layer yielded more sediments, Soil erosion. increased.. general soil. single layer had. highest yields. runoff, sediments followed. soils. two layers, three layers. this indicated, intensity. soil erosion may be decreased. thE increase. numbers. soil layer.:. this study would provide scientific basis. modeling. layered soil infiltration, erosion processes. 展开更多
关键词 LAYERED Soil INFILTRATION RUNOFF EROSION
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Multifunctional core-shell-like nanoarchitectures for hybrid supercapacitors with high capacity and long-term cycling durability
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作者 S.Chandra Sekhar Goli Nagaraju +3 位作者 Bhimanaboina Ramulu Sk.Khaja Hussain D.Narsimulu Jae Su Yu 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第10期2597-2608,共12页
Transition metal oxide/hydroxide with multif unctional hierarchical nano structures has attracted widespread attention in supercapacitors(SCs)because of their large accessible surface area,high electrochemical activit... Transition metal oxide/hydroxide with multif unctional hierarchical nano structures has attracted widespread attention in supercapacitors(SCs)because of their large accessible surface area,high electrochemical activity and superior redox chemistry.Herein,core-shell-like copper(Cu)hydroxide nano tube arrays grafted nickel aluminum layered double hydroxide n anosheets were facilely synthesized on porous Cu foam(CH NTAs@NiAI LDH NSs)for use as an efficient battery-type electrode in hybrid SCs.With the synergistic effects of NiAl LDH NSs on well-adhered CH NTAs/CF,the core-shell-like composite(prepared for 24 h)delivered a maximum areal capacity of 334.3 pAh/cm2 at a current density of 3 mA/cm2 in 2 M KOH electrolyte,which is comparatively higher than other samples synthesized at different growth times.Moreover,the core-shell-like CH NTAs@NiAI LDH NSs-24 demonstrated an outstanding cycling stability of 134.3%after 10,000 cycles.Utilizing high capacity and stability of CH NTAs@NiAI LDH NSs-24,a pouch-type hybrid SC was further assembled with core-shell-like composite as a positive electrode and reduced graphene oxide as a negative electrode with a filter paper as a separator in aqueous alkaline electrolyte.The hybrid SC showed a high areal capacity of 250 pAh/cm2 at 2 mA/cm2 with maximum areal energy and power densities of 181.9 pWh/cm2 and 24,991.5 pW/cm2,respectively.Successfully harvest!ng the solar energy via solar cell panel and subsequently delivering the stored en ergy to switching and proximity applicati ons also dem on strated the real-time applicability of our hybrid SCs. 展开更多
关键词 copper hydroxide layered double hydroxides CORE-SHELL hybrid supercapacitors energy density self-powered devices
Corrosion resistance of Mg(OH)2/Mg-Al-layered double hydroxide coatings on magnesium alloy AZ31: influence of hydrolysis degree of silane
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作者 Qing-Song Yao Zhong-Chao Li +5 位作者 Zai-Meng Qiu Fen Zhang Xiao-Bo Chen Dong-Chu Chen Shao-Kang Guan Rong-Chang Zeng 《稀有金属:英文版》 SCIE EI CAS CSCD 2019年第7期629-641,共13页
Mg(OH)2/Mg-Al-layered double hydroxide (LDH) coatings were modified with methyltrimethoxysilane (MTMS) on magnesium alloys. Effect of hydrolysis degree of silane solution on coating formation was investigated. Chemica... Mg(OH)2/Mg-Al-layered double hydroxide (LDH) coatings were modified with methyltrimethoxysilane (MTMS) on magnesium alloys. Effect of hydrolysis degree of silane solution on coating formation was investigated. Chemical compositions and surface morphologies of the coatings were examined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and field-emission scanning electronic microscopy (FESEM). Results indicated that the composite coatings consisted of polymethyltrimethoxysilane (PMTMS), LDH and Mg(OH)2. Electrochemical and hydrogen evolution measurements revealed that the composite coatings possessed good corrosion resistance, especially the ones prepared in a high hydrolysis degree of silane. The optimum corrosion resistance of the composite coati ng was LDH/PMTMS-3 coating, which had the lowest value of corrosion current density (5.537×10^-9 A·cm^-2) and a dense surface.Plausible mechanism for coating formation and corrosion process of MTMS-modified Mg(OH)2/Mg-Al-LDH coatings were discussed. 展开更多
关键词 Magnesium alloy Layered double HYDROXIDE (LDH) SILANE Coating Corrosion resistance
复合煤层区工作面分层回采技术研究 预览
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作者 张华星 张东旭 肖见兵 《山东煤炭科技》 2019年第9期49-51,共3页
张双楼矿74102工作面内主采的7#煤层与下伏9#煤层存在合成情况,探明复合区内煤厚变异系数较大。为保证资源采出率,根据74102工作面地质情况,确定了基于不同煤层的分层错巷开采方法,提出了以聚酯纤维柔性网作为人工假顶保证下分层回采时... 张双楼矿74102工作面内主采的7#煤层与下伏9#煤层存在合成情况,探明复合区内煤厚变异系数较大。为保证资源采出率,根据74102工作面地质情况,确定了基于不同煤层的分层错巷开采方法,提出了以聚酯纤维柔性网作为人工假顶保证下分层回采时护顶效果,可为类似地质条件下的复合煤层回采技术选择提供参考借鉴意义。 展开更多
关键词 分层 开采 柔性网
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Triple effects of Sn-substitution on Nao.67Nio.33Mno.67O2
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作者 Xiaohui Rong Fei Gao +6 位作者 Feixiang Ding Yaxiang Lu Kai Yang Hong Li Xuejie Huang Liquan Chen Yong-Sheng Hu 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第7期1250-1254,共5页
Layered oxides are one of the most prom ising cathode materials for sodium ion batteries (NIBs), however, the relatively low working voltage hinders the increase of energy density thus limiting the application scenari... Layered oxides are one of the most prom ising cathode materials for sodium ion batteries (NIBs), however, the relatively low working voltage hinders the increase of energy density thus limiting the application scenarios of NIBs. Here we prepared and investigated a series of Sn^4+ substituted NaO.67NiO.33M na67-xSnxO2 (x = 0.10, 0.20, 0.30, 0.33) and found that Sn-substitution can induce three effects: promoting O3-stack formation, sm oothing the voltage profile and increasing the working voltage to -3.6 V. This study would enrich the knowledge of Sn-substitution and give guide to the better design of high-voltage cathode materials for NIBs. 展开更多
关键词 Sodium-ion batteries LAYERED oxide CATHODE Tin-based CATHODE
基于分层马尔可夫模型的冗余配置保护最优检修周期研究 预览
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作者 崇志强 陈培育 +4 位作者 马世乾 于光耀 王旭东 李国栋 郭悦 《中国电力》 CSCD 北大核心 2019年第3期73-80,共8页
为解决基于马尔可夫方法评估冗余配置继电保护系统的可靠性会遇到状态数目多、状态划分难的问题,提出分层马尔可夫可靠性模型。在建立马尔可夫状态空间过程中,根据被保护设备所处的状态将被保护设备和保护装置的状态分为若干层,接着对... 为解决基于马尔可夫方法评估冗余配置继电保护系统的可靠性会遇到状态数目多、状态划分难的问题,提出分层马尔可夫可靠性模型。在建立马尔可夫状态空间过程中,根据被保护设备所处的状态将被保护设备和保护装置的状态分为若干层,接着对每层再进行详细的状态划分,通过双重主保护加后备保护验证提出的可靠性模型并根据相应的可靠性指标求解该配置继电保护系统的最优检修周期。结果表明:继电保护装置的过检修和欠检修对保护系统的可靠性都不利,保护冗余配置比单重配置的可靠性更高,而且最优检修周期也更长,影响继电保护最优检修周期的主要因素是保护自身的可靠性,与被保护设备的可靠性关系不大,同时本方法可解决状态划分过程中的状态遗漏问题。 展开更多
关键词 配电网 可靠性 马尔可夫 继电保护系统 分层 检修周期
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The art of two-dimensional soft nanomaterials
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作者 Caini Zheng Jinhui Zhu +3 位作者 Chongqing Yang Chenbao Lu Zhenying Chen Xiaodong Zhuang 《中国科学:化学英文版》 SCIE EI CAS CSCD 2019年第9期1145-1193,共49页
The discovery of graphene has triggered the explosive development of two-dimensional(2D) nanomaterials, including both inorganic and organic species. Benefiting from the simple elemental composition, inorganic 2D nano... The discovery of graphene has triggered the explosive development of two-dimensional(2D) nanomaterials, including both inorganic and organic species. Benefiting from the simple elemental composition, inorganic 2D nanomaterials were the center research in the past decade, which has long shadowed the research of 2D organic(or soft) nanomaterials. Although many kinds of2D soft nanomaterials have been successfully prepared, a unified definition for them is still impossible due to the complicate and quite different chemical structures between each other and even relying on totally different techniques to distinguish them. Since our first review on 2D soft nanomaterials in 2015, this field has moved forward with big success. In this review, we will focus on the development of 2D soft nanomaterials after 2015. In order to deliver better overview of this field, new and comprehensive classification is used in this review: 2D aromatic molecules, graphene and graphene nanoribbons, graphyne and graphdiyne,BxCyNznanosheets, 2D polymers, 2D supramolecules, crystalline 2D assemblies, 2D covalent organic frameworks, 2D metalorganic frameworks, sandwich-like 2D porous polymers, 2D polymer nanosheets, etc. The focus of this review lies on synthetic strategies and the challenges of characterization, definition and fundamental understanding. 展开更多
关键词 two dimensional SOFT material NANOSHEET LAYERED STRUCTURE sandwich-like STRUCTURE
苯氧甲基青霉素(V-cillin)插层水滑石的制备及表征 预览
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作者 赵大洲 《云南师范大学学报:自然科学版》 2019年第1期47-50,共4页
通过两步法合成药物分子苯氧甲基青霉素(V-cillin)插层水滑石复合物,采用X-射线衍射、差热热重分析、扫描电镜分析、红外光谱和紫外光谱分析表征.结果表明,药物分子V-cillin已经成功嵌入到水滑石层间,形成的复合材料为层状介孔结构,层... 通过两步法合成药物分子苯氧甲基青霉素(V-cillin)插层水滑石复合物,采用X-射线衍射、差热热重分析、扫描电镜分析、红外光谱和紫外光谱分析表征.结果表明,药物分子V-cillin已经成功嵌入到水滑石层间,形成的复合材料为层状介孔结构,层间距约为2.2nm,为药物分子的组装和缓释提供了新的途径. 展开更多
关键词 苯氧甲基青霉素 插层 水滑石 层状
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