非均质土中海上风电单桩基础动力响应特性

采用有限元分析软件ABAQUS建立了非均质土中海上风电单桩基础数值计算模型,将桩基础受到的波浪、洋流及风荷载等效成双向对称循环荷载,对水平循环荷载作用下桩身水平位移、桩身剪力、桩身弯矩和桩侧土抗力进行了研究,并对不同循环次数下桩身水平位移进行了对比分析。研究表明,桩身水平位移随时间变化逐渐累积,随着循环次数的增加,泥面处桩身最大位移发生的时间点滞后;桩身剪力出现负值;桩身弯矩最大值发生在浅层土体;桩身外壁土抗力曲线随时间的变化在埋深约2/3处出现分界点,分界点上下范围内土抗力变化规律正好相反,在淤泥土和粉砂土分界面处增加显著;不同时间点桩身内壁沿埋深承担的荷载基本不变。      

化学工程领域全日制专业学位研究生实践能力培养的研究

实践性是全日制专业学位研究生教育的基本特点。结合本校现阶段化学工程领域全日制专业学位研究生培养中存在的问题,从专业课程教学改革与实践、发展和完善相对开放的实验体系以及提高指导教师自身素质等方面,探讨了化工类专业学位研究生实践能力培养模式的构建。     

Precipitation in a rapidly solidified and aged NiAlMo alloy

The early stages of decomposition of a highly supersaturated nickel-base alloy have been studied using transmission electron microscopy, scanning transmission electron microscopy and X-ray diffraction. The material was produced as a metastable solid solution by chill-block melt-spinning. On ageing the material exhibited a number of decomposition products appearing in series or concomitantly. Some of the decomposition products of this alloy, Ni₄Mo, Ni₃Mo (D0₂₂) and Ni₂Mo, are related to those found in NiMo binary alloys. α-Mo formed during solidification was distinguished from that formed by precipitation in the solid state by orientation relationships.     

耐久超疏水涂层的制备及其防冰防腐自清洁性能

超疏水涂层在防结冰、防腐蚀等领域具有广阔的应用前景,然而目前仍无法大规模制备稳定的超疏水表面。提出一种操作简单、成本低廉的方法,在铝合金基材上通过一步喷涂法制备出耐磨超疏水涂层。首先在铝合金基体表面涂覆环氧树脂粘结层,待其达到半固化状态时,喷涂硬脂酸修饰的微米 SiO₂ 和纳米 TiO₂ 粒子混合悬浮液,固化后该涂层与水的接触角为~ 155.4°,滚动角为~3°,实现了超疏水性。试验结果表明,该超疏水涂层具有较好的耐磨耐久性,在胶带剥离、砂纸摩擦、 紫外光长时间照射以及不同 pH 液滴等多种测试条件下仍具有良好的超疏水性。此外,此超疏水涂层在极端寒冷的天气下可以显著延缓水的冻结时间。环氧树脂和疏水颗粒的协同防腐作用使超疏水涂层在海水中表现出良好的防腐蚀性能。所制备的超疏水涂层还具有优异的自清洁特性,且因 TiO₂ 粒子本身的光降解性能,该涂层还可用于光降解污染物和净化水质。这种简单、环保的超疏水涂层在防结冰、防腐蚀等方面具有潜在的应用前景,可为克服传统超疏水表面使用耐久性差的问题提供解决思路。     

Isolas,mushrooms and oscillations in isothermal,autocatalytic reaction-diffusion equations

The simplest representations of non-linear chemical feedback in an isothermal system are the prototype autocatalytic steps

Such rate-laws arise in both solution-phase and gas-phase kinetics and in biological situations. In the present paper these reactions are coupled with the diffusion of the reactants through a permeable boundary from an external reservoir where the concentrations are held constant.When the autocatalyst reacts further by a first-order decay to a stable product C

a wide range of complex behaviour is possible even for this simple system. The dependence of the stationary-state conversion of A on the experimental conditions may display isola or mushroom patterns (with two branches forming a closed loop or two separate ranges of hysteresis and multiplicity respectively). The stationary-state autocatalyst concentration profile may display multiple internal extrema. Sustained temporal oscillations are also possible, corresponding to stable limit cycles which emerge from Hopf bifurcation points. These are located by local stability analysis and confirmed by extensive computation.     

Mechanical dewatering of peat

The mechanical dewatering of peat by pressing is analysed in terms of the compressibility and the permeability of the peat bed. It is demonstrated that the presence of electrostatically stabilized small particles has a great influence on permeability. Reduction of the electrostatic interactions makes the suspended particles adhere to the peat matrix, thus strongly increasing permeability. The electrostatic interactions can be modified by changing the pH or by adding ionic surfactant, polyelectrolyte or inorganic electrolyte. The combined influence of polycation and reduced pH strongly facilitates mechanical dewatering and has a beneficial influence on the purity of the wastewater, on mineral matter content (and hence ash yield) and on the sensitivity of peat to mechanical pretreatment.     

Differential thermogravimetry of peat fractions

Humic and fulvic acids were extracted from two peat samples designated H2 and H9 on the von Post index. The raw peat, humic acids, fulvic acids and remaining residues were tested using differential thermogravimetry in nitrogen and air. The results indicate peaks in the differential curves characteristic of each fraction. Both similarities and differences are observed; the fractions from the more decomposed H9 peat requiring higher temperatures for gasification and combustion. The results are consistent with general theories of peat formation.     

Similar simulation study on the deformation and failure of surrounding rock of a large section chamber group under dynamic loading

Large and super-large section chamber groups in coal mines are frequently affected by dynamic loads resulting from production activities such as roadway driving and blasting. The stability of the surrounding rock is poor, and it is difficult to control. In this paper, a similar simulation test was used to study the deformation and evolution laws of the surrounding rock of a triangle-shaped chamber group under different dynamic loads. The results showed that under dynamic loading, the vertical stress of the surrounding rock of the chamber group increased in an oscillatory form. The maximum stress concentration coefficient reached 4.09. The damage degree of the roof was greater than that of the two sides. The deformation of the roof was approximately 1.2 times that of the two sides. For the chamber closer to the power source, the stress oscillation amplitude of the surrounding rock was larger, and the failure was more serious. The force of the anchorage structure showed a phased increasing characteristic; additionally, the force of the anchorage structure on the adjacent side of the chambers was greater than that on the other side. This study reveals the deformation and failure evolution laws of the surrounding rock of large section chamber groups under dynamic loading.     

Nouveaux materiaux cathodiques pour generateurs a anode de lithium: Les oxydes mixtes de bismuth et de plomb 2ième partie: Etude électrochimique et radiocristallographique du processus de réduction: New cathode materials for lithium batteries: lead bismuth mixed oxides

The different phases observed during reduction of various Li/(1−n) Bi₂O₃, n PbO cells have been investigated using X Ray analysis and cyclic voltammetry. The results imply a pseudo single-phased behaviour. Comparisons between definite compounds and solid solutions occuring at the same compositions seem to indicate that the discharge kinetics is influenced by the degree of ordering of the ionic network. The existence of a large voltage plateau at 1,5 volt, the high energy density and the very good stability of the initial capacity during long time storage make Li, Bi Pb Oxyde cells specially suitable for watch supply applications.     

不黏煤捕收剂试验及其浮选促进机理研究

低阶煤表面存在大量的含氧官能团,使其在浮选过程中难以很好地完成矿化过程,导致低阶煤浮选产率低.为了解决传统的柴油等极性油捕收剂在低阶煤浮选中选择性较差,不能有效分选的问题,采用一种高效捕收剂对陕西正通煤业不黏煤煤样进行浮选试验,并与柴油作为捕收剂的试验进行了对比.通过红外光谱、拉曼光谱、X射线衍射、X射线光电子能谱、光...