Mechanical Properties and Deformation Behaviors of Metallic Glasses Investigated by Atomic-Level Simulations

The chapter reviewed recent developments about intrinsic structure of metallic glasses and their mechanical properties at atomic level, with an emphasis on making connections between developments in theory and simulations. Topics covered the following: structure analysis on metallic glasses with methods of pair distribution function, Honeycutt-Andersen analysis, and Voronoi tessellation; the connection of structure with the mechanical properties; shear band initiation and the development at the atomic level; and deformation mode transition from cast metallic glasses to reconstructed nanoglasses. These works provided theoretical understanding on the essence of metallic glasses’ mechanical properties and deformation behaviors, and offered promises for more extensive applications of metallic glasses

Multi-perspective Information Fusion Res2Net with RandomSpecmix for Fake Speech Detection

In this paper, we propose the multi-perspective information fusion (MPIF) Res2Net with random Specmix for fake speech detection (FSD). The main purpose of this system is to improve the model's ability to learn precise forgery information for FSD task in low-quality scenarios. The task of random Specmix, a data augmentation, is to improve the generalization ability of the model and enhance the model's ability to locate discriminative information. Specmix cuts and pastes the frequency dimension information of the spectrogram in the same batch of samples without introducing other data, which helps the model to locate the really useful information. At the same time, we randomly select samples for augmentation to reduce the impact of data augmentation directly changing all the data. Once the purpose of helping the model to locate information is achieved, it is also important to reduce unnecessary information. The role of MPIF-Res2Net is to reduce redundant interference information. Deceptive information from a single perspective is always similar, so the model learning this similar information will produce redundant spoofing clues and interfere with truly discriminative information. The proposed MPIF-Res2Net fuses information from different perspectives, making the information learned by the model more diverse, thereby reducing the redundancy caused by similar information and avoiding interference with the learning of discriminative information. The results on the ASVspoof 2021 LA dataset demonstrate the effectiveness of our proposed method, achieving EER and min-tDCF of 3.29% and 0.2557, respectively.Comment: Accepted by DADA202

Genetic analysis and QTL mapping of aroma volatile compounds in the apple progeny ‘Fuji’ × ‘Cripps Pink’

Aroma is an essential trait for apple fruit quality, but the understanding of biochemical mechanisms underlying aroma formation is still limited. To better characterize and assess the genetic potential for improving aroma quality for breeding, many efforts have been paid to map quantitative trait loci (QTLs) using a saturated molecular linkage map. In the present study, aroma profiles in ripe fruit of F1 population between ‘Fuji’ and ‘Cripps Pink’ were evaluated by gas chromatography-mass spectrometry (GC-MS) over 2019 and 2020 years, and the genetics of volatile compounds were dissected. In total, 38 volatile compounds were identified in ‘Fuji’ × ‘Cripps Pink’ population, including 23 esters, 3 alcohols, 7 aldehydes and 5 others. With the combination of aroma phenotypic data and constructed genetic linkage map, 87 QTLs were detected for 15 volatile compounds on 14 linkage groups (LGs). Among them, a set of QTLs associated with ester production identified and confirmed on LG 6. A candidate gene MdAAT6 in the QTL mapping interval was detected. Over-expression of MdAAT6 in tomato and apple fruits showed significantly higher esters accumulation compared to the control, indicating it was critical for the ester production. Our results give light on the mode of inheritance of the apple volatilome and provide new insights for apple flavor improvement in the future

BOND PERFORMANCE OF DEFORMED REBAR IN STEEL FIBER REINFORCED LIGHTWEIGHT-AGGREGATE CONCRETE AFFECTED BY MULTI-FACTORS

For the innovation of building materials, a new high-performance Steel Fiber Reinforced Lightweight-Aggregate Concrete (SFRLAC) made of 100% fine and coarse expanded shales has been developed. In view of the importance of reliable bond properties between deformed rebar and this new SFRLAC, the experimental study of 39 specimens was conducted by using the modified pull-out test method with the evaluation of different slips at loading-end and free-end. In which the influencing factors were considered as the volume fraction of steel fiber, the water-cement ratio, the rebar diameter, the bond length of rebar, the strength of coarse expanded shales and the fine expanded shale replaced by manufactured sand. The complete bond stress-slip curves were measured, the bond failure modes of specimens were observed. Based on the bond mechanism of adhesion, friction and bearing action of deformed rebar in SFRLAC, the bond performance characterized by the bond strength and peak-slip, the differential of bond slip between loading-end and free-end, the bond sustainability in descending portion and the bond failure mode observed are analyzed. The recommendations are proposed for the design of SFRLAC structures related to the bond performance

Low Temperature Nanoindentation: Development and Applications

Nanoindentation technique at low temperatures have developed from initial micro-hardness driving method at a single temperature to modern depth-sensing indentation (DSI) method with variable temperatures over the last three decades. The technique and implementation of representative cooling systems adopted on the indentation apparatuses are discussed in detail here, with particular emphasis on pros and cons of combination with indentation technique. To obtain accurate nanoindentation curves and calculated results of material properties, several influence factors have been carefully considered and eliminated, including thermal drift and temperature induced influence on indenter and specimen. Finally, we further show some applications on typical materials and discuss the perspectives related to low temperature nanoindentation technique

Experimental Study on Chloride Ion Diffusion in Concrete Affected by Exposure Conditions

The transport mechanism of chloride ions in concrete is relatively complicated since the erosion process is influenced by many factors. To investigate the effect of exposure conditions on the chloride ion diffusion property, three exposure conditions (long-term immersion in static sodium chloride solution, long-term immersion in circulating sodium chloride solution and dry–wet cycles in circulating sodium chloride solution) were considered in chloride ion diffusion experiments. Experimental results indicated that the chloride ion content at a certain depth increased with erosion age. The chloride ions in static sodium chloride solution transported more rapidly than those under dry–wet cycle conditions. Moreover, the chloride ion content of concrete under dry–wet cycles of the circulating sodium chloride solution was slightly higher than that under long-term immersion in the circulating solution. Based on Fick’s second law, empirical equations for the chloride diffusion coefficient and chloride content at the surface of concrete were proposed by fitting experimental data, and the values of correlation coefficients of different exposure conditions were suggested. By comparison with the experiment results, it was verified that the calculation formula had better applicability. This method could be used to predict and analyze the chloride ion content under different exposure conditions

Development of Steel Fiber-Reinforced Expanded-Shale Lightweight Concrete with High Freeze-Thaw Resistance

For the popularized structural application, steel fiber-reinforced expanded-shale lightweight concrete (SFRELC) with high freeze-thaw resistance was developed. The experimental study of this paper figured out the effects of air-entraining content, volume fraction of steel fibers, and fine aggregate type. Results showed that while the less change of mass loss rate was taken place for SFRELC after 300 freeze-thaw cycles, the relative dynamic modulus of elasticity and the relative flexural strength presented clear trends of freeze-thaw resistance of SFRELC. The compound effect of the air-entraining agent and the steel fibers was found to support the SFRELC with high freeze-thaw resistance, and the mechanisms were explored with the aid of the test results of water penetration of SFRELC. The beneficial effect was appeared from the replacement of lightweight sand with manufactured sand. Based on the test results, suggestions are given out for the optimal mix proportion of SFRELC to satisfy the durability requirement of freeze-thaw resistance

Bond Properties of Steel Bar in Concrete under Water Environment

The present study concerns the bond behavior of steel bar in concrete under a water environment. This topic was put forward because of the changes of concrete under a water environment and the importance of reliable anchorage of steel bar for reinforced concrete structures. Thirty bond specimens with deformed steel bars were immersed in water and experimentally studied by pull-out tests. The soaking time from 28 day to 360 day and the cubic compressive strength of concrete with 20 N/mm2 and 40 N/mm2 were considered as the main parameters. The results indicate that the moisture content, compressive strength, and splitting tensile strength of concrete are affected by the water environment; the splitting tensile strength varies almost linearly with the compressive strength of concrete; and the descent portion of the bond–slip curve dropped slowly owing to the confinement of stirrups. On the basis of the test data, the formulas for the prediction of bond strength, residual strength, and the corresponding slips with different soaking time are proposed. Finally, the constitutive relation of bond–slip with two portions in the water environment is established with good agreement with the experimental bond–slip curves