Research on design of through-diaphragm connections between CFRT columns and HSS beams

The through-diaphragm connection detail has been identified as a good choice for attaching HSS beams to concrete-filled rectangular tube columns in engineering applications. In this research program an analytical study was conducted to comprehend the behavior of this detail and develop the accompanying design guidelines. The experimental results are presented elsewhere. In this paper two analytical models were established to predict the shear stiffness and yield shear strength of the HSS beam and panel zone, respectively. Theoretical results based on the proposed model well agreed with the experimental data. Finally, design provisions were introduced to check the strength in the connections.     

书香墨气六百年——南京成贤街源流初识

成贤街是南京市跨越六百年历史的文化名街。作者基于实地考察和历史地图及文献,追溯成贤街的文化渊源及明朝以后的历史流变,探讨了其独特的建筑风貌和人文特质。     

大跨度桥梁多模态耦合颤振二分法全自动搜索

在分析和评价国内外对大跨度桥梁风致颤振研究的成果和目前各种常用颤振分析方法优缺点的基础上,基于结构的固有模态坐标,进一步完善了大跨度桥梁多模态耦合颤振的双参数搜索状态空间法。通过将结构和气流作为一个动态系统,最后将颤振问题归结为数学上一个非对称实矩阵的广义特性值问题。在求解中,风速搜索采用了二分法加速收敛技术,频率采用搜索迭代法,该方法可以按指定的搜索精度,迅速搜索到颤振临界风速和颤振频率,无须设定步长,且能真实地给出各阶模态频率和阻尼比随风速的全过程。最后对具有理想平板截面的悬臂梁进行颤振分析验证了本文方法的正确性,同时对总跨度1177m的香港汀九大桥进行颤振分析,计算得到的颤振临界风速基本与风洞试验结果基本一致,进一步表明本文方法的可靠性和高效性。     

Tribological Characteristics of Aqueous Graphene Oxide,Graphitic Carbon Nitride,and Their Mixed Suspensions

The tribological performance of graphene oxide (GO), graphitic carbon nitride (g-C₃N₄), and their mixed (g-C₃N₄/GO) aqueous suspensions was investigated. The 0.06 wt% GO, 0.06 wt% g-C₃N₄, and 0.06 wt% 1:1 g-C₃N₄/GO suspensions reduced the coefficient of friction (COF) by 37, 26 and 37% and wear mark radius by 19.1, 16.0 and 19.6%, respectively, in comparison with water. Pure g-C₃N₄ and GO suspensions showed unstable lubrication in the tests with relatively high loads and speeds, while the g-C₃N₄/GO mixed suspension had superior tribological performance in all tested conditions. This is because in the mixed suspension g-C₃N₄ agglomerates became smaller, and GO nanosheets exhibited fewer wrinkles and less stacking, which enabled the formation of a layer of tribo-composite film. As a result, the friction, wear and tribo-corrosion were reduced during sliding.     

Experimental study on the life prediction of servo motors through model-based system degradation assessment and accelerated degradation testing

The advent of smart factories has resulted in the frequent utilization of industrial robots within factories to increase production automation and efficiency. Due to the increase in the number of industrial robots, it has become more important to prevent any unexpected breakdowns of the factory. As a result, the lifespan prediction of machinery has become a crucial factor because such failures can be directly associated with factory productivity resulting in significant losses. Most of the failures occur within one of the core components of the robot arm, the servo motor, and thus we will focus on the analysis of the servo motor in this study. However, sensor attachment to such equipment is considered difficult due to the dynamic movement of the robot arm, meaning that internal instrumentation should be utilized during analysis. In addition, no definite measure to determine the degradation of the motor exists, and thus a new degradation index is proposed in this study. Therefore, in this study, the lifespan of the servo motor will be estimated through accelerated degradation testing methods based on a new system degradation assessment method, which estimates the fault of the system using observer-based residuals with encoder data obtained from internal instrumentation.     

A physical strategy for the preparation of isotactic polypropylene spheres with microsphere and bead–string spherulite morphologies

This study mainly focuses on the formation of isotactic polypropylene (iPP) blend morphologies with microspheres and distinct bead–string spherulites. iPP microspheres have been prepared by a simple and convenient strategy through either an isothermal or a nonisothermal crystallization process based on the macrophase‐separated structure in molten state of iPP/olefin block copolymer (OBC) blend. The dimension of the iPP spheres can be adjusted easily from about 1 µm to >10 µm by controlling the compatibility and annealing conditions. It was found that any of the following three parameters, the molecular structure of OBC (particularly the octene content), molecular weight of iPP, and annealing condition can be rescaled with others in controlling the dimension of the iPP microspheres. The mechanism of the formation of iPP microspheres was studied in detail. Surprisingly, the typical spinodal decomposition morphology with interconnected or thin sheet structure is the precursor of these microspheres. During the subsequent annealing process, it breaks up and further coarsens into spherical structure. In addition, distinct spherulites with a bead–string substructure have been obtained during the isothermal crystallization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40863.     

Thermal degradation behavior and gas phase flame‐retardant mechanism of polylactide/PCPP blends

The thermal degradation behavior of the blend based on polylactide (PLA) and poly(1,2‐propanediol 2‐carboxyethyl phenyl phosphinate) (PCPP) was investigated by the thermogravimetric analysis (TGA). Thermal degradation activation energies (E_a) of neat PLA and PLA/15% PCPP blend were calculated via the Flynn–Wall–Ozawa method. The E_a of the blends increased with the addition of PCPP increasing when the conversion was higher than 10%. In addition, the appropriate conversion models for the thermal degradation process of PLA and PLA/15% PCPP were studied via the Criado method. At the same time, the main gaseous decomposition products of PLA and its blend were identified by TGA/infrared spectrometry (TGA–FTIR) analysis. And it revealed that the PCPP improved the flame‐retardant property of PLA via altering the release of the flammable gas and nonflammable gas. Moreover, the PCPP improved the flame‐retardant property of PLA by inhibiting exothermic oxidation reactions in the combustion, which was further proved by pyrolysis–gas chromatography–mass spectrometry analysis. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40480.     

Injury Mechanisms of Lactic Acid Bacteria Starter Cultures During Spray Drying: A Review

Lactic acid bacteria (LAB) starter cultures can be processed by many drying techniques, among which spray drying has great potential. However, injuries of LAB during spray drying lead to a low survival rate. The microbial injuries of LAB during spray drying are specifically induced by dehydration inactivation, thermal inactivation, and balance between the two. To reduce the drying temperature, new drying techniques based on spray drying were tried; that is, low-temperature vacuum–spray drying and spray–freeze drying.     

Palladium and Copper Cocatalyzed Intermolecular Cyclization Reaction: Synthesis of 5‐Aminopyrazole Derivatives

A novel and efficient palladium and copper co‐catalyzed intermolecular cyclization of acetonitriles with hydrazones has been developed for the synthesis of 5‐aminopyrazoles through C C and C N bond formation. The reaction has the advantages of easily available starting materials, simple manipulation and mild reaction conditions. The reaction involving various substituted acetonitriles and hydrazones proceeds smoothly and 5‐aminopyrazoles are synthesized in good yields. In contrast to the aliphatic and heteroaromatic substrates, the aromatic substrates tend to have a higher degree of reactivity.