纳米流体悬浮稳定性和电导率的关系研究

基于Maxwell电磁理论中电解质悬浮液中粒子质量分数和电导率之间的关系,提出了一种判定纳米流体悬浮稳定性的方法,并进行了实验验证。实验中,采用"两步法"经超声振荡制备了CuO/去离子水纳米流体。利用电导率仪测量了不同质量分数时纳米流体的电导率,建立了质量分数与电导率的关系,同时研究了温度对电导率的影响。结果表明电导率随着颗粒质量分数的增加而增加,随着质量分数的减小而减小;随着温度的增长,电导率只有微小变化,可以忽略温度对电导率的影响。     

A Horizontality Adjusting Study of the Earth Drill＇s Platform

A horizontality adjusting system of the earth drill‘s platform is designed to deal with the operation difftculty of the platform which appeared while the earth drill is used. The proportional-impulse control to eliminate the over-adjustment and electricity-hydraulic-proportional control to drive the adjusting mechanism are adopted in the system. The control scheme and control algorithm are introduced in detail. The software flow chart is given.     

Study on the Agile Virtual Enterprise＇s Organizing Form and Running Environment

In this paper, we begin with the swift changes in the knowledge economy time, analyze the implication of the agility, and consider the agile virtual enterprise as the main organizational form for the manufacturing enterprises to realize agility. We classify the agile virtual enterprises into products alliance style and knowledge alliance style, and compares their main features and profit distribution models. As a result, we give four basic structures for the building and running of the agile virtual enterprises.     

Research on the Relationship between Density of States and Conducting Properties of Single-walled Carbon Nanotubes

The analytical expression of the electronic density of states (DOS) for single-walled carbon nanotubes (SWNTs) has been derived on the basis of graphene approximation of the energy E(k) near the Fermi level EF. The distinctive properties of the DOS, the normalized differential conductivity and the current vs bias for SWNTs are deduced and analyzed theoretically. The singularities in the DOS (or in the normalized differential conductivity) predict that the jump structure of current (or conductance)--bias of SWNTs exists. All conclusions from the theoretical analysis are in well agreement with the experimental results of SWNT‘s electronic structure and electronic transport. In other words, the simple theoretical model in this paper can be applied to understand a range of spectroscopic and other measurement data related to the DOS of SWNTs.     

The relationship between the electrical and mechanical properties of polymer–nanotube nanocomposites and their microstructure

A range of polymer–nanotube nanocomposites were produced using different processing routes. Both polymer-grafted and as-grown nanotubes were used and latex and polystyrene matrices investigated. The microstructures of the nanocomposites were studied, mainly by electron microscopy, in terms of the dispersion state of the nanotubes and the polymer–nanotube interface. The mechanical and electrical properties of the composites were also measured. The relationship between the microstructures observed and the resulting physical properties are discussed. It is found that composites with apparently similar microstructures can exhibit similar mechanical properties but very different electrical behaviours. Moreover, the nanocomposites produced using polymer-grafted nanotubes exhibit a clear improvement of the stress at large deformation. Thus, from our results, it appears that the mechanical and electrical properties do not necessarily depend on the same microstructural parameters. However it is still a challenge to simultaneously improve both physical properties.     

Relations between the Lattice Parameter and the Stability of Austenite against ε Martensite for the Fe-Mn Based Alloys

The influences of lattice parameter of austenite, the electron concentration, the yield strength of parent phase on γ→ε emartensite start temperature Ms in the Fe-Mn alloys containing C, Al, Ge and Si have been experimentally investigated. The results show that the lattice parameter of austenite is more important than the electron concentration and the yield strength of parent phase in governing the γ→ε martensitic transformation in Fe-Mn based alloys. A relation between the Ms and lattice parameter of austenite in Fe-Mn based alloys is suggested. The elements Mn, C, Al, Ge, which increase the lattice parameter of austenite lower the Ms; while the element Si, which decreases the lattice parameter increases the Ms. The depressing effect of antiferromagnetic transition on the γ→ε martensitic transformation may be related to the increase of lattice parameter due to the positive magnetostriction during the antiferromagnetic transition.     

Increasing the Resolution and SNR of an ADC＇s Measurement with a Method of OverSampling and Averaging

By analyzing the theory of over-sampling and averaging, the conclusion is educed that white noise accompanies the signal and the addition of each bit of resolution can be achieved via a fourfold sampling frequency. The addition of each bit will approximately increase the SNR （signal to noise ratio） to 6dB.     

The relationship between the a.c. impedance and microstructure of a sodium β-alumina ceramic

A comparison is made between the microstructures, resistivities and strengths of sodium /-alumina samples prepared under different firing conditions. Double peak firing schedules are shown to result in samples of higher strength with a narrower grain-size distribution and lower resistivity than those produced by single peak firing. Complex plane a.c. impedance and admittance data show the sodium ion conduction over the temperature range 173 to 300 K to be governed primarily by intergranular regions of the sample (with the resistance varying with grain size) whilst resistivity measurements at 623 K show the conduction to be primarily intragranular controlled at elevated temperatures.     

Study of the Development Road Map of China’s Renewable Energy

Renewable Energy (RE) has been attached high attention around the world due to its carbon-free and indigenous production in a sustainable way. China enjoys plenty of renewable energy resources, particularly the wind, solar ,hydro and biomass energy, which could be a sound basis for a large-scale exploitation. This report examines the current status of RE technology and industry, analyzes the challenges of promoting RE in China. In order to pave the way for a long-term development of RE, this paper outlines the basic principles and priorities for individual RE technology. In line with these, the paper puts forward the RE targets and further describes the RE Roadmap by 2020, 2030 and extende to 2050, taking consideration of China’s RE resources, industrial basis and energy demand etc. At last, this paper provides some recommendations to ensure the achievements of the RE targets.     

添加TiO2纳米颗粒和分散剂的相变流体粘度实验研究

选定质量分数为30%的烃类相变流体作为基液,采用"两步法"配制了多种添加纳米颗粒(TiO_2)及分散剂(SDBS十二烷基苯磺酸钠)的相变流体,测试分析了纳米颗粒质量分数、粒径及分散剂质量分数对相变流体粘度的影响。结果表明,相同温度下,纳米颗粒质量分数越大,纳米颗粒粒径越大,相变流体粘度越大。而相变流体粘度随分散剂质量分数增大呈先减小后增大的趋势,当分散剂质量分数为0.1%时,相变流体粘度达到最小。     

Photography and Writing,or the Intimacy of the Image: A Dialogic Encounter between Barthes’s Camera Lucida and Blanchot’s Philosophy of Otherness

This article was prompted by James Elkins’s argument — developed in his book, What Photography Is, from 2011 — that there is no actual relationship between Roland Barthes’s theory of photography and Maurice Blanchot’s philosophy. Drawing on considerations of an historical, philosophical, and literary nature, the article argues for the importance of a dialogic encounter between Barthes and Blanchot, demonstrating that the interconnection between the concepts of intimacy, image, and writing, appears as a crucial aspect in the theory of both authors. At the same time, by contesting Elkins’s wider criticism of Barthes’s Camera Lucida (1982), the article aims to develop better-informed theoretical understandings of Barthes’s thoughts on photography. The final section of the article attempts to map promising points of connection between Barthes, Blanchot, and Proust, in order to reassess the notion of punctum in its broader relation with the concepts of time and death.     

Magnesia supported Au and Ag catalysts for the preparation of few-layer graphene–metal nanocomposites: relationship between catalyst structure and the properties of graphene composites

Magnesia supported Au, Ag, and Au–Ag nanostructured catalysts were prepared, characterized, and used to synthesize few-layer graphene–metal nanoparticle (Gr–MeNP) composites. The catalysts have a mezoporous structure and a mixture of MgO and MgO·H₂O as support. The gold nanoparticles (AuNPs) are uniformly dispersed on the surface of the Au/MgO catalysts, and have a uniform round shape with a medium size of ~8 nm. On the other hand, the silver nanoparticles (AgNPs) present on the Ag/MgO catalyst have an irregular shape, larger diameters, and less uniform dispersion. The Au–Ag/MgO catalyst contains large Au–Ag bimetallic particles of ~20–30 nm surrounded by small (5 nm) AuNPs. Following the RF-CCVD process and the dissolution of the magnesia support, relative large, few-layer, wrinkled graphene sheets decorated with metal nanoparticles (MeNPs) are observed. Graphene–gold (Gr–Au) and graphene–silver (Gr–Ag) composites had 4–7 graphitic layers with a relatively large area and similar crystallinity for samples prepared in similar experimental conditions. Graphene–gold–silver composites (Gr–Au–Ag) presented graphitic rectangles with round, bent edges, higher crystallinity, and a higher number of layers (8–14). The MeNPs are encased in the graphitic layers of all the different samples. Their size, shape, and distribution depend on the nature of the catalyst. The AuNPs were uniformly distributed, had a size of about 15 nm, and a round shape similar to those from Au/MgO catalyst. In Gr–Ag, the AgNPs have a round shape, very different from that of the Ag/MgO catalyst, large size distribution and are not uniformly distributed on the surface. Agglomerations of AgNPs together with large areas of pristine few-layer graphene were observed. In Gr–Au–Ag composites, almost exclusively large bimetallic particles of about 25–30 nm, situated at the edge of graphene rectangles have been found.     

The relationship between the occurrence of twin-related laths and the fracture elongation in the two-phase (α+γ) Fe-Cr-Ni stainless steel

The relationship between the occurrence of twin-related laths and fracture elongation has been studied in two-phase (+) Fe-Cr-Ni stainless steel. The percentage of adjacent twin-related lath martensites increased as the deformation temperature increased from –196 to –50° C. The appearance of these twin-related laths, having the accommodation effect, contributed to the increase in elongation.     

Microcoil NMR Study of the Interactions between Doxepin, β-Cyclodextrin, and Acetate during Capillary Isotachophoresis

The capillary isotachophoresis (cITP) separation of the isomers of the tricyclic antidepressant doxepin using β-cyclodextrin (β-CD) as a buffer additive is investigated by online microcoil NMR detection. Capillary electrophoresis (CE) is also used to determine the binding constant between the doxepin E and Z geometric isomers and β-CD. Although the doxepin isomers could be easily baseline resolved by CE, their separation by cITP was more challenging due in part to the high concentration of doxepin after cITP-focusing. The use of online (1)H NMR detection allows observation of changes in doxepin dynamics due to formation of the β-CD inclusion complex, changes in the fraction complexed and the intracapillary pH. It also provides novel experimental evidence that a weak complex between β-CD and acetate contributes to its active transport from the leading electrolyte through the sample band to the trailing electrolyte in this cationic cITP separation. The results of these cITP-NMR experiments provide new mechanistic details about the interactions of the buffer counterion acetate with various components of the separation system and have important implications for other analyses based on formation of cyclodextrin inclusion complexes.     

Al2O3纳米流体相变特性的DSC研究

纳米流体相变时所体现出的特性是其作为蓄冷相变材料使用的重要基础。利用差示扫描量热法分别测量了纳米颗粒粒径为10nm、20nm、50nm、100nm、500nm,质量分数为5%、10%、12%、15%、20%,以及降温速率为2℃/min、3℃/min、5℃/min、7℃/min、9℃/min的Al2O3纳米流体的凝固点、冰点、融化点、比热及相变潜热的影响。测量结果表明:纳米流体的凝固点、冰点值都高于去离子水;随着颗粒粒径、质量分数和降温速率的增加,纳米流体的凝固点、冰点逐渐升高,而比热值逐渐减小。融化温度随着颗粒粒径、质量分数的增加而增加,且随着降温速率的增加而小幅度的降低。去离子水的相变潜热值高于纳米流体的潜热值;随着纳米颗粒粒径的增加,潜热值越大;随着质量分数和降温速率的增加,相变潜热值越小。     

On the relation between Schubert’s h-index of a single paper and its total number of received citations

A relation, established by András Schubert (Scientometrics 78(3): 559–565, 2009) on the relation between a paper’s h-index and its total number of received citations, is explained. The relation is a concavely increasing power law and is explained based on the Lotkaian model for the h-index, proved by Egghe and Rousseau.     

Study on the relation between the refractive index of fresh muscle tissue and its water content from 400 to 750 nm

Refractive index dispersion (RID) of fresh tissue is highly related to water content. However, there is no experimental investigation about their relationship for a wide spectral range. In this study, with the aid of a previously proposed lab-made apparatus, the RID of fresh and fully-dehydrated mutton muscle samples were measured over the continuous spectral range from 400 to 750 nm. The mass fractions and volume fractions were also measured. Results showed that the RID of fresh muscle tissue equals to the sum of fully-dehydrated tissue RID and water RID multiplied by their respective volume fractions. The results in this study also experimentally proved that the effective medium theory of refractive index is applicable for tissue analysis.