Metallic glass-based chiral nanolattice: Light weight,auxeticity, and superior mechanical properties

Metallic glasses (MGs) possess large elastic limit and high strength, but unfortunately they are of limited commercial utility due to their macroscopic brittle nature. Here, we report that a chiral nanolattice can be used to design large-scale MGs with negative Poisson’s ratio, large elastic deformation capability, extensive hardening, and large ductility. Furthermore, the mechanical behaviors of the metallic glass chiral nanolattice (MGCN) can be significantly altered through changing the thickness and length of the ligaments in the nanolattice. An exceptional combination of high strength and ductility is observed for MGCN with thin and long ligaments, wherein the sample density is only twice that of water. The deformation mechanism that characterizes the chiral topology is a combination of rotation of the nodes with bending and extension of the ligaments, leading to the extraordinary mechanical behaviors. The present study not only offers a potential solution to mitigating the brittleness of MGs, but also provides some guidelines in designing large-scale MG meta-materials for prospective applications in the fields of acoustics and energy absorption.     

新型水性阻尼材料在汽车涂装中的应用

为减轻汽车行驶过程中的振动噪音,提高轿车的舒适性,使轿车噪声值满足法规要求,需在车身内部采用防声、防震、吸声材料。本文叙述了新型水性阻尼材料(LASD)的特点,介绍了LASD的汽车涂装工艺和设备,对LASD涂装应用的难点问题提供了预防及解决方法。     

Design of a discrete-time output-feedback based repetitive-control system

This paper deals with the problem of designing a robust discrete output-feedback based repetitive-control system for a class of linear plants with periodic uncertainties. The periodicity of the repetitive-control system is exploited to establish a two-dimensional (2D) model that converts the design problem into a robust stabilization problem for a discrete 2D system. By employing Lyapunov stability theory and the singular-value decomposition of the output matrix, a linear-matrix-inequality (LMI) based stability condition is derived. The condition can be used directly to design the gains of the repetitive controller. Two tuning parameters in the LMI enable the preferential adjustment of control and learning. A numerical example illustrates the design procedure and demonstrates the validity of the method.     

Textural quality of sweet dumpling: effect of germination of waxy rice

Effects of germination on components and structural changes of rice flours and, in turn, rheological properties and textural attributes of sweet dumplings were investigated in this study. Germination decreased starch, protein and lipid content, while slightly increased free amino acids content. Starch granular surface corroded, crystalline structure disrupted, and short-range ordered structures and helical structures decreased with germination. Moreover, germination resulted in a decreased paste viscosity and gel intensity of flour and a reduction of hardness and adhesiveness of dumplings. According to the Pearson’s correlation analysis, flours components and starch structures were significantly correlated with flours rheological properties that determined textural attributes of sweet dumplings. The germination contributed to significant changes in flours components and starch structures, which suggested the pretreatment of germination of waxy rice could be a promising pathway to control textural properties of sweet dumplings.     

A Close Look at the Urban Planning and Development in Asia——A Review on Asian Cities: Planning and Development

正Asian Cities:Planning and Development Editors:Wu Jiang, Zhang Fan, Sha Yongjie, Xia Liping Year:2018 Publisher:Tongji University Press ISBN:9787560875774 1. Publishing background The Asian Cities:Planning and Development edited by Prof. Wu     

Numerical analysis of carbon saving potential in a top gas recycling oxygen blast furnace

Aiming at the current characteristics of blast furnace(BF)process,carbon saving potential of blast furnace was investigated from the perspective of the relationship between degree of direct reduction and carbon consumption.A new relationship chart between carbon consumption and degree of direct reduction,which can reflect more real situation of blast furnace operation,was established.Furthermore,the carbon saving potential of hydrogen-rich oxygen blast furnace(OBF)process was analyzed.Then,the policy implications based on this relationship chart established were suggested.On this basis,the method of improving the carbon saving potential of blast furnace was recycling the top gas with removal of CO_2 and H_2O or increasing hydrogen in BF gas and full oxygen blast.The results show that the carbon saving potential in traditional blast furnace(TBF)is only 38-56kg·t~(-1) while that in OBF is 138kg·t~(-1).Theoretically,the lowest carbon consumption of OBF is 261kg·t~(-1)and the corresponding degree of direct reduction is 0.04.In addition,the theoretical lowest carbon consumption of hydrogen-rich OBF is 257kg·t~(-1).The modeling analysis can be used to estimate the carbon savings potential in new ironmaking process and its related CO_2 emissions.     

Unstructured Polygonal Finite-Volume Solutions of Radiative Heat Transfer in a Complex Axisymmetric Enclosure

Radiative heat transfer in a complex axisymmetric enclosure with participating medium is investigated by using the finite-volume method (FVM). In particular, an implementation of the unstructured polygonal meshes is adopted by connecting each center point of the unstructured triangular meshes rather than joining the centroids of the triangular elements to the midpoints of the corresponding sides to form a polygonal element. Also, typical considerations regarding application of the present polygonal mesh system to axisymmetric radiation are discussed. After a mathematical formulation and corresponding discretization equation for the radiative transfer equation (RTE) are derived, the final discretization equation is introduced with the conventional finite-volume approach by using the directional weights. For validation and comparison, three test examples with complex axisymmetric geometries have been accomplished. The present study shows that not only is the method flexible in treating radiative problems with complex geometries, it is also accurate and efficient for the analysis of axisymmetric radiative heat transfer.     

Synthesis,characterization, and properties of acrylate‐modified tung‐oil waterborne insulation varnish

An acrylate‐modified tung‐oil waterborne insulation varnish was synthesized from tung oil, maleic anhydride, and acrylates via a Diels–Alder reaction and free‐radical polymerization, and the varnish could be solidified at a relatively low temperature with blocked hexamethylene diisocyanate as a curing agent. The resulting films were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The insulation properties (electrical insulation strength, volume resistivity, and surface resistivity) of the varnish films were tested, and the resistances of films to salted water were evaluated. With an increase in the maleic anhydride content, the thermal stability of the film was improved, whereas the electrical insulation strength, volume resistivity, and surface resistivity decreased. The electrical insulation strength of the film after it was immersed in the NaCl solution was lower than that in dry state, and it decreased as the immersed time was prolonged. In particular, the electrical insulation strength loss of the film increased significantly at maleic anhydride contents beyond 25 wt %. Furthermore, the hardness of the film increased with increasing methyl methacrylate/N‐butyl acrylate ratio, whereas the flexibility and adhesion of film decreased to a certain degree at the same time. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41608.     

Characteristics of hemicelluloses obtained from sweet sorghum based on successive extractions

Hemicelluloses were successively extracted from sweet sorghum by hot water, dioxane, DMSO, and different concentrations of NaOH between 0.5% and 6.0%. The yields of the seven fractions together accounted for 88.6% of the original hemicelluloses. The obtained hemicellulosic subfractions were comprehensively investigated by both destructive methods such as alkaline nitrobenzene oxidation and acid hydrolysis and nondestructive techniques such as gel permeation chromatography, Fourier‐transform infrared, ¹³C‐nuclear magnetic resonance, and 2D‐heteronuclear singular quantum correlation. Sugar composition studies showed that the water‐soluble polysaccharides consisted mainly of glucose, while xylose, arabinose, and glucuronic acid were the major sugars in other hemicellulosic fractions. It was found that the hemicelluloses from sweet sorghum were l‐ arabino‐(4‐O‐methyl‐d‐ glucurono)‐xylans. Comparison with the hemicellulosic fractions dissolved by the alkali treatment, the hemicellulosic fraction extracted by DMSO had lower molecular weight. In addition, it was also found that the hemicelluloses prepared by dioxane and DMSO were more branched since that they had higher nonxylose/xylose ratios than those extracted by the alkali treatment, which were more linear and contained higher amounts xylose. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42790.