Study of the effect of a number of oxidizers on variation of composition of surface functional groups,porous structure,and adsorption properties of composite carbon-carbon sorbent

The oxidation of a carbon-carbon composite sorbent by a number of oxidants results in the variations of the chemical nature of the surface, including an increase in the overall content of surface oxygen-containing groups and, in separate cases, increased variations in its structure-chemical characteristics, primarily in an increase in the percentage of large mesopores. The oxidative modification of the initial sorbent increases the hydrophilicity of its surface and enhances the specific sorption of water vapors.     

图的着色理论在自动导引小车调度规划系统中的应用

针对目前AGVS(自动导引小车系统)的调度问题的研究现状,为解决AGVS在FMS(柔性制造系统)中的调度次数最优化的问题,文章提出通过图的着色理论来研究满足一定约束的AGVS中调度问题,为满足此类约束条件的AGVS,给出一种行之有效的方法.理论分析结果表明,该方法能够在完成调度任务的同时,能够使AGVS的调度次数最优.图的着色理论对于此类问题的研究,较传统的方法,运算简单,求解直观.与此同时,该方法还可以确定此类问题背景下的系统所需小车的最小值.     

Effect of the velocity of equal-channel angular pressing on the formation of the structure of pure aluminum

Transmission electron microscopy, X-ray diffraction, and electron back-scattering pattern analysis have been used to investigate the effect of the speed of equal-channel angular pressing (ECAP) at room temperature on the formation of ultrafine-grained structure in pure aluminum. It has been established that eight ECAP passages with a pressing speed of 3.3 × 10^?2 mm/s results in the formation in aluminum of a substantially inhomogeneous grain structure with a grain size in the range of 1–27 μm (average size 3.0 μm). An increase in the speed of pressing by an order of magnitude leads to an increase in the level of internal stresses and dislocation density, an increase in the upper boundary of the interval of the grain-size distribution and in the average grain size (to 3.4 μm), and a decrease in the number of boundaries with high-angle misorientations. It is assumed that these changes are connected with the fact that processes of dislocation-structure relaxation have no time to occur during the ECAP at high pressing speeds.     

Evolution of misorientation spectrum of grain boundaries of submicrocrystalline molybdenum upon deformation under conditions of grain-boundary diffusion of nickel

Comparative investigations of the concurrent evolution of the structure and the misorientation spectrum of grain boundaries of submicrocrystalline molybdenum have been performed upon free annealing and under the creep conditions at a temperature of 1023 K. It has been established that changes in the misorientation spectrum of grain boundaries of submicrocrystalline molybdenum upon annealing and creep are observed concurrently with boundary migration. The grain-boundary diffusion of nickel upon annealing leads to an increase in the fraction of grain boundaries of the special type with Σ17a in the grain-boundary ensemble of submicrocrystalline molybdenum. Under the creep conditions grain-boundary diffusion fluxes of nickel atoms favor transformation of low-angle boundaries into high-angle boundaries and growth in the angle of misorientation of the high-angle boundaries of submicrocrystalline molybdenum to 45°–60°.     

Conductivity of aqueous suspensions of alumosilicates

When studying the electrochemical properties of diluted suspensions of natural and modified bentonite, the correlation between the inductive component of the system’s resistance and the temperature has been established. It confirms the hypothesis on the presence of paramagnetic particles in the system, whose solubility decreases with the growth of the temperature. Active forms of oxygen, as generated in the near-electrode space, can be such particles. It is shown that, in model systems, hydrogen peroxide is formed in this space due to the reversible dissociative adsorption of oxygen on platinum in the presence of a suspension electrode with proton conductivity.     

阿那其根醇提取物对两种炎症模型作用机制研究

目的: 研究阿那其根醇提取物(EERAP)对二甲苯致小鼠炎症模型和脂多糖(LPS)诱导RAW264.7细胞炎症模型的影响。方法: 将50只小鼠,随机分为对照组(饮用水)、EERAP高剂量组(640 mg/kg)、中剂量组(320 mg/kg)、低剂量组(160 mg/kg)和阿司匹林组(120 mg/kg),采用二甲苯建立小鼠炎症模型,比较小鼠耳廓肿胀度及耳廓毛细血管通透性的变化,ELISA法测定各组炎症渗出液丙二醛(MDA)、超氧化歧化酶（SOD）的含量;LPS诱导RAW264.7细胞建立细胞炎症模型,ELISA法测定核转录因子kappa B（NF-κB）和肿瘤坏死因子-α（TNF-α）含量。 结果: 在二甲苯致小鼠炎症模型中,EERAP高、中、低剂量组均能抑制小鼠耳廓肿胀度,减少小鼠耳廓毛细血管通透性,减少渗出率,与空白对照组比较均有统计学差异(P<0.01);EERAP高、中、低剂量组均能降低血清中MDA含量（P<0.05）,显著升高SOD含量(P<0.01);在LPS诱导的RAW264.7细胞炎症模型中,EERAP在3.125～200 μg/mL范围内可降低TNF-α含量,而在2 μg/mL时也可以降低细胞NF-κB含(P<0.05),与阿司匹林组无统计学差异。结论: EERAP可能是通过抑制MDA、TNF-α和NF-κB的生成,升高SOD的水平,起到抗炎、抗氧化作用。     

滑阀污染敏感尺寸的确定

本文根据滑阀运动副发生污染卡紧与污染磨损的污染物尺寸条件,给出了滑阀污染敏感尺寸范围。试验结果很好地证明理论分析的正确性。这对于确定液压系统中滑阀所需要的过滤精度具有重要价值。     

Peculiarities of polyaniline matrix synthesis in the presence of mixtures of different types of matrices and investigation of properties of formed interpolymer complexes

In the present work, the existence of a matrix domination effect in the formation process in polyaniline interpolymer complex solutions under aniline oxidation in the presence of rigid and flexible poly(amidosulfonic acid)s was demonstrated for the first time.     

Simulation of formation of surface roughness of corroding materials

The article discusses the process of heterogeneous corrosion using a 3D model of metal consisting of two uniformly intermixed phases destroyed at different rates. The model describes the decrease in the rate of corrosion and the increase in roughness, as well as the formed microrelief of corroded metal as a function of the exposure time. The theoretical equations are verified by computer experiments.     

Kinetics of dissolution of phases upon deformation of nanostructured metals and alloys

The kinetic features of dissolution of foreign inclusions in the bulk of nanostructured metals upon plastic deformation have been discussed. It has been shown that the rate of dissolution of inclusions substantially depends on the character of structural transformations in the subsystem of intercrystallite boundaries of nanomaterials. Equations that determine the kinetics of dissolution of chemical compounds of metals depending on the rate of structural transformations in intercrystallite boundaries upon deformation have been obtained. The behavior of the kinetic curves of dissolution has been described qualitatively. Numerical estimates of the time of dissolution of inclusions Fe₃C and Fe₂B in steels are given which are in satisfactory agreement with experimental data on the mechanical alloying of iron with nonmetals in ball planetary mills.     

On size effect of rate of corrosion of copper nanowire ensemble: Part 2. Size effect of rate of corrosion of copper in pyrophosphate solution

The corrosion of specimens of copper produced by electroplating on disc electrodes 10–500 μm in diameter from a pyrophosphate electrolyte is studied in this electrolyte (without added copper ions) using polarization curve measurements. It is found that the rate of corrosion of the microelectrodes with a radius of 5 μm is eight times higher than that of the microelectrodes with a radius of 25 μm; the measured rate of corrosion remains unchanged when varying the radius of the microelectrode in a range of 25–250 μm. It is shown that the process under investigation is corrosion with oxygen depolarization; the rate of reduction (of dissolved oxygen) increases eightfold when varying the radius of the microelectrode in a range of 5–25 μm. The experimental results are confirmed by the calculations of diffusion currents for the microelectrodes, which show that the size effect, i.e., an increase in the diffusion current density with decreasing area of the electrode surface, should be observed for electrodes with a radius less than 20–30 μm.     

Calculation of the parameters of pulsed laser welding of thin sheets of aluminium alloys

One of the main advantages of the MIG/MAG process is its high productivity. In most of the applications, positive polarity is used, due to its greater arc stability, generation of less splatter and formation of weld beads with suitable geometry. However, in some applications, there is a need for greater production capacity than that offered by conventional MIG/MAG welding. In the literature, it is stated that negative polarity provides a higher fusion rate than positive, despite leading to a high level of splatter and unsuitable formation of the weld bead. Unfortunately, there is not much information available on the effects of the process variables in this polarity, much less justification for such. Therefore, this work is an attempt to try to understand the reason why there is a higher deposit rate in negative polarity, as well as the related effect on the geometry of the weld beads. To do this, comparative MIG/MAG welds were produced in both positive and negative polarities, using two compositions of shielding gases at two current values. The transfer mode and the behaviour of the arc were analysed by synchronized profiling. The geometric profile of the weld bead was evaluated by means of metallographic procedures. From the results, which disagree in part with the current literature, it was seen that both the transfer mode as well as the morphology and the appearance of the weld bead are dependent on the composition of the shielding gas. To explain the phenomena inherent in the greater fusion rate of wire in DC ? , the suggestion is that the fact that arc scales the sides of the wire in this polarity may be the governing factor.     

基于事例推理技术在夹具CAD中应用的研究

通过对夹具在机械加工设备中的作用，夹具的设计过程，现代计算机辅助设计技术在夹具设计中的应用和事例推理技术的分析，提出了基于事例推理（CBR）技术的夹具半智能化设计系统的总体设计和夹具结构设计方案。     

The assessment of the value of GPR imaging of flexible pavements

A survey of the different applications of ground penetrating radar (GPR) for highway pavement investigation is presented with a critical appraisal of the success with which it was applied. The problems associated with this technique are also discussed. These include discussions of the accuracy of the technique and the difficulties in trying to interpret the recorded signals. Suggestions for the future direction of the research in this field to enhance the data collection and interpretation are made. The remainder of this paper investigates the advances that can be made in the use of existing GPR technology in the field of thin pavements investigation.     

Zn固溶量对Mg-Zn-Y合金组织的影响

利用电化学相分离法,成功提取Mg-Zn-Y合金中的第二相,并获得合金元素在Mg-Zn-Y合金中的固溶量,建立了镁合金中直接测定元素固溶量的方法。利用Miedema混合焓模型及Toop模型(对称)和Kohler模型(非对称)计算Mg-Zn-Y三元合金中Zn的活度及活度相互作用系数,通过实验测定及计算表明：Mg-Zn-Y中Zn的自相互作用系数与Y的相互作用系数均为正值,说明这一体系里Zn与Zn,Zn与Y是相互排斥的,Y的存在可以提高Zn的活度,即Y固溶量的增加会导致Zn固溶量的降低,增加了固液界面前沿液相中的成分过冷度,从而使得晶粒细化,晶界处片层状的Mg₃Y₂Zn₃共晶相聚集增多,逐渐连续成网状。     

钛铁矿烧结性能研究

将钛铁矿在氩气及空气气氛中不同温度下进行烧结。采用XRD及热分析研究了钛铁矿在不同温度下烧结后的相组成及质量变化。结果表明,在氩气气氛950℃下烧结后,钛铁矿的物相组成没有发生变化;在空气中不同温度烧结后,600～800℃较低温度区间,钛铁矿转变为热力学亚稳定的Fe2Ti3O9,950℃以上烧结时,钛铁矿转化为热力学稳定的Fe2TiO5。钛铁矿的晶体结构由烧结前的三方结构经低温烧结后转变为亚稳态六方晶系的Fe2Ti3O9,950℃以上烧结后,晶体结构转变为斜方晶系的Fe2TiO5。     

Inhibition of copper corrosion by coatings of alkyl esters of carboxybenzotriazole

The inhibitive effect of coatings formed dipping copper in solutions of alkyl esters (methyl, butyl, hexyl and octyl) of carboxybenzotriazole was studied by potentiodynamic polarisation, electrical impedance spectroscopy, coulometry and surface enhanced Raman scattering (SERS) spectroscopy. The inhibition efficiency of the dry film depends on type of solvent used in the coating solution, temperature and period of immersion. Pretreatment by immersing copper in hot (70 °C) aqueous solution (1×10⁻⁴ M) for approximately 2-3 h gave a film with the highest degree of corrosion protection. Higher temperatures or longer time of immersion reduce the protectiveness of the film. Copper coated using either alcohol or acetone as solvent was less well protected than when dipped in aqueous solution. Impedance spectra showed that the film formed by pretreatment in aqueous solution of inhibitors can be stable in acidic sulphate corrodent (pH∼0) for up to 3 days before breaking down. In near-neutral sulphate solution (pH∼8) the film can be stable for up to 10 days. In both acidic and neutral sulphate solution, the inhibition efficiencies of the protective film increased with the length of the alkyl ester chain in the order: methyl < butyl < hexyl < octyl. This is different to the behaviour of copper in a near-neutral aqueous corrodent containing dissolved inhibitor. The ester films also exhibit anti-tarnishing properties in a sulphidising environment with inhibition efficiencies increasing as the alkyl chain is made longer. Again the films formed by pretreatment in aqueous solution have superior anti-corrosion properties compared to those formed by pretreatment in either alcohol or acetone solution. SERS measurements indicate that the azole ring is close to the copper surface with chemisorption through azole nitrogen. It is also suggested that the hydrocarbon chain of the ester is physically adsorbed on the copper.     

Mechanism of improvement of formability in pulsating hydroforming of tubes

The mechanism of improvement of formability by the oscillation of internal pressure in a pulsating hydroforming process of tubes was examined. Free bulging hydroforming experiments of mild steel tubes under oscillating and constant inner pressures were performed. For a high constant pressure, a round bulge with local thinning was observed, whereas wrinkling occurred for a low constant pressure. The occurrence of these defects was prevented by oscillating the internal pressure in the pulsating hydroforming. In the pulsating hydroforming, a uniform expansion in the bulging region was obtained, and thus the formability was improved by preventing the local thinning. It was found from an observation of deformation behaviour, using a video camera, that the tube is uniformly expanded by repeating the appearance and disappearance of small wrinkling. The cause of the uniform expansion for the pulsating hydroforming was also interpreted from the variation of stress components. In addition, a similar deference in deformation behaviour between the oscillating and constant inner pressures was also obtained in finite element simulation.     

Investigation of thermomechanical characteristics of shape-memory alloys of the Ti-Ni-Nb system and of the effect of heat treatment on them

The properties of shape-memory titanium nickelide-based alloys alloyed with niobium have been investigated for use in developing progressive technology for thermomechanical joints of pipelines and cylindrical elements of constructions of couplings fabricated from these alloys. In the process of the investigations, the elemental and phase compositions of alloys of the Ti-Ni-Nb system in the cast and pressed states have been determined; their microstructure, kinetics, and temperatures of phase transformations have been studied; the main mechanical characteristics have been determined; the thermomechanical characteristics and the effect of different types and regimes of heat treatment on them have been investigated. The results of these investigations confirmed the suitability of the alloys for use in thermomechanical joints of pipelines; couplings can be stored at temperatures of up to 40°C without a loss of deformation induced in them. By changing certain mechanical and thermomechanical characteristics of alloys of the Ti-Ni-Nb system in the cast and pressed states using different types and regimes of heat treatment, the field of employment of these materials can be expanded.