Tar sand extractions with microemulsions: I-the dissolution of light hydrocarbons by microemulsions using 2-butoxyethanol and diethylmethylamine as cosurfactants

For oil sand extractions with microemulsions it is important to disperse large quantities of light hydrocarbons in an aqueous medium. Fundamental studies on the properties of 2-butoxyethanol (BE) and diethylmethylamine (Et₂McN) in water suggest that these two liquids could be more effective cosurfactants than the usual alcohols used for this purpose. The phase diagrams of microemulsions using BE and Et₂MeN as cosurfactants, combined with typical ionic and non-ionic surfactants and typical aliphatic and aromatic hydrocarbons, were therefore investigated and compared with microemulsions based on n-butanol. Although the phase diagrams depend significantly on the nature of the surfactant and of the oil, the monophasic region generally increases with the cosurfactant in the order n-butanol < Et₂McN < BE. With the active mixture BE-cetyltrimethylammonium bromide, temperature has little effect on the phase diagram and NaCl generally destabilizes the microemulsion.     

基于MWSPCA-CBR的智能预警方法研究及其在石化工业中的应用

石油钻井是一项高风险性、耗资巨大的系统工程。为了智能预警石油钻井过程中的异常，缩短非生产时间，降低相关风险，提出一种基于移动窗稀疏主元分析法（MWSPCA）的案例推理（CBR）异常智能预警方法（MWSPCA-CBR）。首先利用MWSPCA算法分析钻井过程中的实时数据，快速定位出异常可能发生的时间，然后使用基于案例推理方法分析异常数据，确定可能的异常类型，并为实时监控专家提供相关异常的处理方法。所提方法应用到石油钻井过程异常预警中，实验结果验证了所提方法的可行性和有效性，为钻井过程降低风险成本提供了新思路。     

Re-GAN：残差生成式对抗网络算法

目的 生成式对抗网络（generative adversarial network,GAN）是一种无监督生成模型,通过生成模型和判别模型的博弈学习生成图像。GAN的生成模型是逐级直接生成图像,下级网络无法得知上级网络学习的特征,以至于生成的图像多样性不够丰富。另外,随着网络层数的增加,参数变多,反向传播变得困难,出现训练不稳定和梯度消失等问题。针对上述问题,基于残差网络（residual network,ResNet）和组标准化（group normalization,GN）,提出了一种残差生成式对抗网络（residual generative adversarial networks,Re-GAN）。方法 Re-GAN在生成模型中构建深度残差网络模块,通过跳连接的方式融合上级网络学习的特征,增强生成图像的多样性和质量,改善反向传播过程,增强生成式对抗网络的训练稳定性,缓解梯度消失。随后采用组标准化（GN）来适应不同批次的学习,使训练过程更加稳定。结果 在Cifar10、CelebA和LSUN数据集上对算法的性能进行测试。Re-GAN的IS （inception score）均值在批次为64时,比DCGAN （deep convolutional GAN）和WGAN （Wasserstein-GAN）分别提高了5%和30%,在批次为4时,比DCGAN和WGAN分别提高了0.2%和13%,表明无论批次大小,Re-GAN生成图像具有很好的多样性。Re-GAN的FID （Fréchet inception distance）在批次为64时比DCGAN和WGAN分别降低了18%和11%,在批次为4时比DCGAN和WGAN分别降低了4%和10%,表明Re-GAN生成图像的质量更好。同时,Re-GAN缓解了训练过程中出现的训练不稳定和梯度消失等问题。结论 实验结果表明,在图像生成方面,Re-GAN的生成图像质量高、多样性强;在网络训练方面,Re-GAN在不同批次下的训练具有更好的兼容性,使训练过程更加稳定,梯度消失得到缓解。     

基于图表示学习的消息回复关系判断方法

微信、QQ和钉钉等社交媒体都提供多对多聊天群组功能,这些聊天群组包含海量信息,对群组聊天内容进行有效分析,获取有价值的关联信息,是当前领域的研究热点。群组中用户间交互是群组实现的主要功能,用户间消息回复是用户间交互实现的方式,消息间的回复行为下隐藏着消息间和用户间的关系。群组消息间回复通常是隐式和非连续的,大部分群组消息间没有指定明确的回复关系,当前消息也不一定是上一条临近消息的回复,回复关系要根据具体的聊天场景确定。当消息间没有显示指定回复关系时,回复不易于分析和理解群组聊天内容,阻碍了对群组聊天内容的整体性分析。本论文针对群组消息间的回复关系,提出了基于图表示学习的消息回复关系判断方法,该方法不同于以往方法仅使用部分群组要素,是在综合学习消息的文本信息、发送消息的用户信息和上下文信息的基础上,根据群组内容构建群组图和生成自适应消息图,得到了多种群组要素信息和要素间关系组成的图结构,利用图模型在图结构上进行群组消息的表示学习,图模型输出群组消息的表示向量,拼接消息对的表示向量并进一步预测群组消息间的回复关系。在消息间回复关系的学习过程中,图模型通过任务学习更新图中消息节点,同时更新图中用户节点向量表示,经过用户向量分析实验验证了该模型输出的用户向量的有效性和合理性。在公开数据集和标注数据集上进行了对比实验和显著性检验分析,结果显示模型在多个评估指标上大幅优于对比模型,如在F1指标上,比单纯依赖BERT的句子对分类模型提高了接近20%。     

Effects of annealing processes on Cu<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Si<Subscript>1-<Emphasis Type="Italic">x</Emphasis></Subscript> thin films

The Cu _x Si_1-x thin films have been grown by pulsed laser deposition (PLD) with in situ annealing on Si (001) and Si (111), respectively. The transformation of phase was detected by X-ray diffraction (XRD). The results showed that the as-deposited films were composed of Cu on both Si (001) and Si (111). The annealed thin films consisted of Cu + η”-Cu₃Si on Si (001) while Cu + η’-Cu₃Si on Si (111), respectively, at annealed temperature (T _a) = 300-600 °C. With the further increasing of T _a, at T _a= 700 °C, there was only one main phase, η”-Cu₃Si on Si (001) while η’-Cu₃Si on Si (111), respectively. The annealed thin films transformed from continuous dense structure to scattered-grain morphology with increasing T _a detected by field emission scanning electron microscope (FESEM). It was also showed that the grain size would enlarge with increasing annealing time (t _a).     

Morphology study of oriented SmBCO film deposited by MOCVD

c-axis-oriented SmBa_2Cu_3O_7(SmBCO) films have been deposited on(100)- LaA1O_3(LAO)substrate by metal organic chemical vapor deposition(MOCVD) technique.The effects of deposition temperature(T_(dep)) and total pressure(P_(tot)) on the orientation and microstructure of SmBCO films were investigated.The orientation of SmBCO films transformed from α-axis to c-axis with increasing of T_(dep) from 900 to 1 100℃.At T_(dep)=1 050℃,SmBCO films had c-axis orientation and tetragon surface.At P_(tot)~(dep)=400-800 Pa and T_(dep)=1 050 ℃,totally c-axis-oriented SmBCO films were obtained.The R_(dep) of SmBCO films increased firstly and then decreased with increasing P_(tot).The surface of SmBCO films exhibited tetragon morphology at 1 050 ℃ and400 Pa.Maximum thickness of SmBCO film deposited was 1.2μm at P_(tot)= 600 Pa,and the corresponding R_(dep)was 7.2 μm·h~(-1).     

An analytic study on the deflection of subway tunnel due to adjacent excavation of foundation pit

Predicting and estimating the response of subway tunnel to adjacent excavation of foundation pit is a research focus in the field of underground engineering. Based on the principle of two-stage method and incremental method, an analytic approach is suggested in this paper to solve this problem in an accurate and rapid way, and the upheavals of tunnel due to adjacent excavation are solved by analytic method. Besides, the presented method is used in the practical engineering case of Shenzhen Metro Line 11 and verified by numerical simulation and in situ measurement. Finally, a parametric analysis is performed to investigate the influence of different factors on tunnel’s deflection. Some useful conclusions have been drawn from the research as below: The deflection results of tunnel obtained from analytic method are nearly consistent with the results getting from numerical analysis and measured data, which verified the accuracy and rationality of presented method. The excavation size has a significant impact on both the displacement values and influenced range of tunnel. However, the relative distance only impacts the displacement values of tunnel, but not the influenced range of tunnel. It may provide certain reference to analyze the deflection of subway tunnel influenced by adjacent excavation.

     

Annealing effects on the structure and hardness of helium-irradiated Cr2AlC thin films

Cr₂AlC MAX phase thin films prepared by radio-frequency magnetron sputtering were irradiated at room temperature by 100 keV helium ions to a fluence of 1 × 10¹⁷ ions cm⁻². The effects of thermal annealing on the structural and mechanical properties of the helium-irradiated Cr₂AlC films as well as the helium release were investigated by grazing-incidence X-ray diffraction (GIXRD), Raman spectroscopy, and scanning electron microscope (SEM) in combination with nano-indentation and elastic recoil detection (ERD) analysis. The irradiation-induced structural damage in the Cr₂AlC is significantly recovered by thermal annealing at temperatures around 600℃, attributed to high defect diffusivity. After annealing to 750℃, the hardness of irradiated films recovered almost completely, which is ascribes to both defect recombination and reformation of damaged chemical bonds. Substantial helium release occurring at this annealing temperature is closely related to the damage recovery due to helium irradiation.     

Theoretical study on composition-dependent properties of ZnO·nAl2O3 spinels. Part II: Mechanical and thermophysical

Knowledge on the mechanical and thermophysical properties of ZnO·nAl₂O₃ is essential for practical applications. Based on the first-principles calculations and the bond valence method, the disordered spinel-type structure of ZnO·nAl₂O₃ (n = 1–4) was constructed to investigate the composition-dependent mechanical and thermophysical properties. The effects of cation substitution on the hardness, elastic modulus, thermal expansion, and thermal conductivity were revealed from the insights into the chemical bonds. At a higher n, the tetrahedral bond is stronger, manifested as its higher hardness and bulk modulus as well as smaller thermal expansion coefficient. Meanwhile, the octahedral bond is weaker, leading to the lower hardness and bulk modulus, along with the larger expansion coefficient. In consequence, the hardness and elastic moduli of ZnO·nAl₂O₃ are improved moderately while the expansion coefficient is decreased with the rise of n. Due to the different vibration characteristics of Zn^IV and Al^IV, the cation disorder in the 8a site provides the primary source of phonon scattering, resulting in the dramatic reduction of thermal conductivity as n increases. The understanding offers guidance on the application-oriented design of new oxide spinels.     

高阻相对La2／3Ca1／3MnO3低场磁电阻效应的影响

实验研究了La2／3Ca1/3MnO3系统晶界上掺杂(YSZ)对其输运性能和磁电阻效应(MR)的影响。样品是由溶胶．凝胶法制成的。通过对样品的电输运特性的测量表明,在掺杂量(x)低于2％时,掺杂引起电阻的增大并降低了金属．绝缘体转变温度;当掺杂量高于2％时电阻逐渐减小,且转变温度增加。而低场磁电阻效应随掺杂量增加,在x=1％时达到最大。