唐长安坊内用地的二元性对其形态演变的影响

唐长安坊内用地存在一种二元性，是因制度的影响不同而使同一空间范围呈现出权贵用地和普通坊民用地空间权益显著差异的状态。文章从土地分配、向街连通、用地管理、违章处置四方面论证了这种二元性的制度根源，涵盖了制度的立法、行政、执法三部分。二元性导致的兼并与买卖、租赁与经营等现象加剧了坊内空间管理的复杂化，在经济发展和社会变迁的影响下，推动了唐长安里坊形态的演变。     

Effect of thermal treatment on the antioxidant activity of egg white hydrolysate and the preparation of novel antioxidant peptides

Heat treatment will affect the nutritional properties and potential bioactivity of food materials. The aim of this work was to evaluate the effect of different thermal treatment (4, 56, 65 and 100 ℃) and in vitro gastrointestinal digestion on the antioxidant activity of egg white hydrolysate. The results demonstrated that egg white hydrolysate treated at 65 ℃ exhibited the highest antioxidant. Remarkably, the simulated digestion significantly increased antioxidant activity of egg white hydrolysate. Furthermore, we identified twenty-four potential antioxidant peptides by performing mass spectrometry and bioinformatic analysis. Six peptides were selected based on the activity prediction score of the online tool. The results showed that P6 (ACPECPK) possessed the most outstanding antioxidant properties and had low cytotoxicity and allergenicity. Bioinformatics technology combined with biochemical assays may offer a way for discovering novel antioxidant peptides from different kinds of food under various heat treatment conditions.     

First Principle and Experimental Study for Site Preferences of Formability Improved Alloying Elements in Mg Crystal

Some alloying elements (Al, Er, Gd, Li, Mn, Sn, Y, Zn) were proved recently by calculations or experiments to improve the formability of Mg alloys, but ignoring their site preference in Mg crystals during the calculated process. A crystallographic model was built via first principle calculations to predict the site preferences of these elements. Regularities between doping elements and site preferences were summarized. Meanwhile, in the basis of the crystallographic model, a series of formulas were deduced combining the diffraction law. It predicted that a crystal plane with abnormal XRD peak intensity of the Mg-based solid solutions, compared to that of the pure Mg, prefers to possess solute atoms. Thus, three single-phase solid solution alloys were then prepared through an original In-situ Solution Treatment, and their XRD patterns were compared. Finally, the experiment further described the site preferences of these solute atoms in Mg crystal, verifying the calculation results.     

Fabrication and Characterization of Highly Oriented Composite Nanofibers with Excellent Mechanical Strength and Thermal Stability

Here, highly‐oriented poly(m‐phenylene isophthalamide)/polyacrylonitrile multi‐walled carbon nanotube (PMIA/PAN‐MWCNT) composite nanofiber membranes with excellent mechanical strength and thermal stability are successfully produced using electrospinning. It is demonstrated that the cooperation of multi‐walled carbon nanotubes (MWCNT) and high‐speed rotating collection is beneficial to the acquisition of highly oriented fibers and effectively improves the mechanical strength of the membrane along the orientation direction. Specifically, the tensile stress of poly(m‐phenylene isophthalamide)/polyacrylonitrile (PMIA/PAN) membrane is enhanced significantly from 10.6 to 20.7 MPa, benefiting from the highly oriented alignment of the fibers as well as the reinforcing effect of MWCNTs on the fibers. Furthermore, the stressing process of single fiber and fiber aggregates is carefully simulated, and the influence of MWCNTs on the mechanical properties of PMIA/PAN‐MWCNT membranes is analyzed comprehensively, providing a meaningful auxiliary means for the study of mechanical properties. In addition, the composite nanofiber membrane has the advantages of both PMIA and PAN, possessing high temperature resistance, flame‐retardancy, and chemical stability, for an ideal high‐temperature material. In short, the as‐prepared PMIA/PAN‐MWCNT composite membrane with excellent comprehensive property emerges a promising application in many fields, especially in high‐tech.     

退火温度对HA/Ti-24Nb-4Zr复合材料组织与性能的影响

利用放电等离子烧结(SPS)技术制备了HA/Ti-24Nb-4Zr生物复合材料,研究了不同退火温度对复合材料显微组织和力学性能(抗压强度、屈服强度、屈强比、压缩弹性模量)的影响。结果表明,烧结态复合材料主要由β-Ti相、少量初生α-Ti相及HA相组成;随着退火温度的升高,复合材料基体中β-Ti相含量增多且晶粒逐渐长大,针状次生α-Ti相在晶界处和晶内不断析出,HA相结构和含量变化不大;与烧结态相比,不同退火温度处理后的复合材料强度和弹性模量先略微上升后下降,而塑韧性呈不断提高趋势;复合材料在850 ℃退火处理后,抗压强度、屈服强度、屈强比和压缩弹性模量值分别为1507 MPa、1270 MPa、0.84和42 GPa,塑韧性得到明显改善,作为生物医用植入材料具有潜在的应用前景。     

氢气非预混燃烧的流场输运特性分析

采用高精度直接数值模拟的方法对氢气非预混燃烧流场进行了精细的预测.模拟所求解的控制方程为三维可压缩的无量纲形式的Navier-Stokes方程,采用六阶精度紧致差分格式,结合基于详细化学反应和输运过程的FGM化学反应机制,利用768个处理器核、共近4.53亿网格点进行了基于CPU的大规模高效并行计算,分析氢气非预混燃烧特性,并进一步探讨了浮力对氢气燃烧流场输运特性的影响.研究发现,由于氢气燃烧过程中产生不同扩散性质的化学组分,使燃烧过程中遵循优势扩散的行为.这将影响流场的输运特性和火焰不稳定性的形成.在浮力驱动的氢气优势扩散燃烧流场中,对流是质量、动量及热量输运行为的主要影响因素,而无浮力火焰中优势扩散主导着流场的输运特性.平均统计结果表明,有浮力和无浮力的燃烧流场中都可以捕捉到逆梯度输运现象,且浮力会促进逆梯度输运行为的发生.     

井下作业面巷道切顶卸压施工设计探究

以井下作业面巷道切顶卸压施工设计为对象开展探究,结合具体工程实际,从切顶卸压爆破施工设计和爆破施工分析两个角度,对切顶卸压技术的全面应用进行总结分析,希望能够为其他矿井相似工程的开展提供借鉴与参考。     

基于条件信息卷积生成对抗网络的图像识别

传统的图像识别方法需要大量有标签样本进行训练，且模型训练难以达到稳定。针对这些问题，结合条件生成网络和信息最大化生成网络的结构优势建立了条件信息卷积生成网络（C-Info-DCGAN）。模型增加图像的类别信息和潜在信息作为输入数据，然后利用Q网络去更好地发挥类别信息和潜在信息对训练的引导作用，并且利用深度卷积网络来加强对图像特征的提取能力。实验结果表明，该方法能够加快模型训练收敛速度，并有效提高图像识别的准确率。