氮气泡沫驱发泡剂优选及油层适应性室内实验

氮气泡沫驱是普通稠油开采后期的一种经济可行的接替技术,可以大幅度提高剩余油采收率。氮气泡沫驱取得效果的一个重要前提是选择发泡性能好,泡沫阻力大的发泡剂。采用静态和动态实验对几种初选的发泡剂进行了优选,选出了性能最优的发泡剂;并进行了可视化实验,对氮气泡沫驱油层适应性进行了研究,表明非均质模型泡沫驱效率均低于均质模型,但在残余油状态下,非均质模型泡沫驱增油效果要明显高于均质模型。储层非均质性越严重,水驱残余油状态下,泡沫驱油的增产效果越显著。对于非均质严重的储层,矿场泡沫驱油增产效果更好。

Preparation of TiO2, CeO2, and ZrO2 hierarchical structures in "one-pot" reactions

In this paper, a novel template of carbon foam is used in building hierarchical structures of TiO2, CeO2, and ZrO2. They had multiscale morphologies, from nanowalls, nanoparticles to layer nanostructures. Oil a hundred-micron scale, the product was a sponge-like material constructed by nanowalls. On a hundred-nanometer scale, the electron microscope images showed that the nanowalls were porous and assembled by polycrystalline nanoparticles. Meanwhile, on one nanometer scale, many nanoparticles exhibited layer nanostructures with about 1.1 run of thickness and spacing. In mechanism section, the process analysis and characterizations suggested that the hierarchical structures were the combined result of two templates in a "one-pot" reaction. The mesoporous nanowalls were derived from carbon foams, while the layer nanostructures were the replicas of graphite sheets. The method has potential utilizations in preparation of various adsorbent and catalyst.

SBS as template to synthesize 3D siliceous mesostructured cellular foams

A mesostructured cellular foam (MCF) with three-dimensional (313) disordered strutlike structure is prepared by using triblock copolymer (poly(styrene-b-butadiene-b-styrene), SBS, M-W = 140K) as template under strong acid conditions. It is the first report to use triblock copolymer with both hydrophobic head and tail groups instead of hydrophilic head and hydrophobic tail copolymers to synthesize siliceous mesostructured cellular foams. The resulted materials have high pore volume (0.92 cm(3)/g) and relatively narrow pore size distributions with a large pore size of 7.9 nm, which will allow for the fixation of large active complexes, reduce diffusional restriction of reactants and enable reactions involving bulky molecules to take place, especially.

Annealing effects on the surface morphologies of thin PS/PMMA blend films with different film thickness

The surface morphology evolution of three thin polystyrene (PS)/polymethyl methacrylate (PMMA) blend films (<70 nm) on SiOx substrates upon annealing were investigated by atomic force microscopy (AFM) and some interesting phenomena were observed. All the spin-coated PS/PMMA blend films were not in thermodynamic equilibrium. For the 67.1 and the 27.2 nm PS/PMMA blend films, owing to the low mobility of the PMMA-rich phase layer at substrate surfaces and interfacial stabilization caused by long-range van der Waals forces of the substrates, the long-lived metastable surface morphologies (the foam-like and the bicontinuous morphologies) were first observed. For the two-dimensional ultrathin PS/PMMA blend film (16.3 nm), the discrete domains of the PS-rich phases upon the PMMA-rich phase layer formed and the secondary phase separation occurred after a longer annealing time.

A microwave emissivity model of sea surface under wave breaking

With the effective medium approximation theory of composites, a remedial model is proposed for estimating the microwave emissivity of sea surface under wave breaking driven by strong wind on the basis of an empirical model given by Pandey and Kakar. In our model, the effects of the shapes of seawater droplets and the thickness of whitecap layer (i.e. a composite layer of air and sea water droplets) over the sea surface on the microwave emissivity are investigated by calculating the effective dielectric constant of whitecaps layer. The wind speed is included in our model, and the responses of water droplets shapes, such as sphere and ellipsoid, to the emissivity are also discussed at different microwave frequencies. The model is in good agreement with the experimental data of microwave emissivity of sea surface at microwave frequencies of 6.6, 10.7 and 37GHz.

Application of effective medium approximation theory to ocean remote sensing under wave breaking

Based on the effective medium approximation theory of composites, the empirical model proposed by Pandey and Kakar is remedied to investigate the microwave emissivity of sea surface under wave breaking driven by strong wind. In the improved model, the effects of seawater bubbles, droplets and difference in temperature of air and sea interface (DTAS) on the emissivity of sea surface covered by whitecaps are discussed. The model results indicate that the effective emissivity of sea surface increases with DTAS increasing, and the impacts of bubble structures and thickness of whitecaps layer on the emissivity are included in the model by introducing the effective dielectric constant of whitecaps layer. Moreover, a good agreement is obtained by comparing the model results with the Rose's experimental data.

工业机器人虚拟样机系统的研究

该文提出将虚拟样机技术应用于工业机器人仿真研究过程 ,研究与开发工业机器人虚拟样机系统。首先说明虚拟样机技术并分析其关键技术 ,然后说明了工业机器人虚拟样机系统的构成与样机系统在机器人仿真研究中的研究内容。总结该项技术主要解决以下两方面的问题 ,即机器人仿真研究中的系统集成及为以机器人为主体的生产线虚拟设计、验证环境提供底层的数字化环境

面向快速成形的复杂曲面重建技术研究

针对快速成形工艺特点，提出了一种基于实物的复杂曲面几何重 建的方法。由此直接生成的快速成形机优化STL接口文件，实现了反求容差与模型网格数的 最佳匹配，避免了由通用软件转换存在的错误和繁复，提高了成形设备的前处理效率，并为 反求工程与快速成形技术的有机集成提供了可靠途径。

快速成型技术中分层算法的研究与进展

根据对零件制造精度和效率的关注程度的不同,开发出了多种分层算法。在同等加工时间的情况下,根据加工精度的不同,将这些分层算法分为等层厚分层算法和适应性分层算法两类。通过对STL模型、原始CAD模型和点云数据的分析,讨论了两类分层算法的研究和发展,然后介绍了斜边分层算法和曲面分层算法等先进分层算法的原理和成果,最后讨论了快速成型分层算法的研究方向和趋势。

金属粉末激光成形过程中的检测与闭环控制研究

金属粉末激光成形技术是基于快速原型(Rapid Prototyping，RP)技术基础上发展起来的一项新型金属零件加工技术。该技术利用高能量激光束直接作用在金属粉末上，可以直接成形高熔点、形状复杂或异质材料功能梯度零件，其成形过程是按照零件几何形状，利用金属粉末逐层逐道累积成形零件的。其独特的金属零件加工特点使其得到了迅速发展，在航空、军事、医学和汽车等众多领域得到了成功应用，并发挥了重要作用。作为一项新兴技术，金属粉末激光成形技术不可避免的存在一些问题，由于激光成形过程是一个多参数影响的过程，成形过程中各参数存在较强的耦合作用，参数的不稳定往往导致成形效果难以保证，例如成形零件外形尺寸精度低、内部组织性能不佳等。这一问题，引起了国内外许多学者的关注，对加工过程中的一些重要参数与成形效果之间的关系展开研究，通过对成形过程中的一些中间过程输出参数进行实时检测，并实现闭环反馈控制，从而达到改善成形产品质量的目的。本文正是在这种背景下进行研究的，本文对熔池场几何尺寸、熔池温度场、熔覆高度与熔覆宽度实时检测进行了深入研究并实现了切实可行的检测方法，在实践中取得了较好的效果，并进行了熔覆成形过程动态辨识，研究了成形过程控制方法，提出了具有较强自适应能力的模糊PID控制方法，取得了较好的仿真效果。本课题主要研究工作有以下几个方面。 1. 激光成形过程中的熔池场包含大量的过程信息，对熔池进行实时检测，并提取熔池特征信息，为熔池场的闭环控制提供依据。为此建立了熔池场实时检测视觉传感系统，实现了图像采集、图像处理和信息提取等功能，课题成功的进行了硬件系统构建和软件系统开发。 2. 实现了红外图像比色测温法在金属粉末激光成形过程中熔池温度场检测中的应用。研究了测温原理，完成了硬件双波长图像采集系统的构建，对滤光片波长进行了选择并对选择结果进行了仿真。阐述了软件测温实现过程。 3. 激光加工过程中，对熔覆高度进行实时检测，从而实现熔覆高度闭环控制是成形高质量零件的保证。加工过程是一个多参数耦合的非线性过程，在分析激光参数对熔覆高度影响的基础上，建立利用激光工艺参数预测熔覆高度的BP神经网络模型，为实现激光加工过程熔覆高度实时预测与闭环控制打下了基础。 4. 熔覆宽度是激光成形过程中与成形效果密切相关的中间过程输出参数，该参数的实时检测为调整扫描间距，确定合理搭接率，提高熔覆表面平整度具有重要作用。提出了一种基于卡尔曼滤波技术的激光熔覆宽度检测方法。利用视觉传感系统获取激光加工过程中的熔池图像，经过图像处理求熔池宽度作为参量建立系统状态方程和测量方程，应用卡尔曼滤波原理对图像上的熔宽和熔宽变化进行状态估计，得到最小均方差条件下的熔覆宽度最佳预测值，从而减小过程噪声和测量噪声引起的熔覆宽度测量偏差，实现加工过程熔覆宽度的精确检测。 5. 成形过程动态辨识，利用阶跃响应法进行了激光参数与熔覆高度、熔覆宽度的辨识实验，建立了激光功率、扫描速度、送粉速率与熔覆高度、熔覆宽度之间的数学模型，对成形过程有了基本了解，为控制器设计与动态过程调节规范确立打下良好基础。 6. 设计了PID熔覆高度控制系统，并利用遗传算法进行了PID参数寻优，寻优获得的参数可以实现较好的控制效果，但不适于实时控制过程。为此设计了模糊PID控制系统，利用模糊逻辑算法对PID参数实现在线自动调整，控制系统具有较强的适应能力和实时处理能力，对于金属粉末激光成形过程具有较好的控制效果。