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Multi-behavior recommendation systems exploit multi-type user–item interactions (e.g., clicking, adding to cart and collecting) as auxiliary behaviors for user modeling, which can alleviate the problem of data sparsity faced by traditional recommendation systems. The key point of multi-behavior recommendation systems is to make full use of the auxiliary behavior information for the learning of user preferences. However, there are two challenges in existing methods that need to be explored: (1) capturing personalized user preferences based on multiple auxiliary behaviors, especially for negative feedback signals; and (2) explicitly modeling the semantics between auxiliary and target behaviors, and learning the explicit interactions between multiple behaviors. To tackle the two problems described above, we propose a novel model, called explicit behavior interaction with heterogeneous graph for multi-behavior recommendation (MB-EBIH). In particular, we first construct a heterogeneous behavior graph, including both positive and negative behaviors. A pre-trained model based on graph neural network (GNN) is then used to generate explicit behavior interaction values as the edge weights for the heterogeneous behavior graph. These weights reflect the importance of each of the auxiliary behaviors in an explicit manner. Finally, the extracted explicit behavior interaction information is incorporated into the multi-behavior user–item bipartite graphs to learn better representations. Experimental results on four real-world datasets demonstrate the effectiveness of our model in terms of exploring multi-behavioral data; and ablation and analysis experiments further demonstrate the effectiveness of explicit behavior interaction information. [ABSTRACT FROM AUTHOR]

Effects of the number of welding passes on microstructure and properties of 2219-C10S aluminum alloy tungsten inert gas (TIG) welded joints were analyzed in detail. The first capping weld had a solid solution effect on the backing weld. The second capping weld had a solid solution effect on the backing weld close to the capping weld and had an aging effect on the backing weld away from the capping weld. The sizes and quantities of the second phases in partially melted zone (PMZ) and over-aged zone (OAZ) increased slightly with the number of welding passes increased. The hardness of OAZ decreased slightly and its width increased slightly. The larger strain distribution range before tensile fractured of the joints was narrower and the range of plastic deformation of the joints was not significantly improved. The eutectic structure and θ phase at weld toes were not conducive to the tensile properties of joints. The tensile properties of double-pass welded joints were relatively ideal. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is to theoretically estimate fatigue crack initiation life of metallic materials using the three-parameter model. For this purpose, correlations between the three parameters and conventional mechanical properties are established. The three parameters are fatigue ductility coefficient, fatigue ductility exponent, and theoretical strain endurance limit. Based on the correlations, the three parameters can be theoretically estimated, and thus the fatigue crack initiation life of metallic materials can be predicted in the absence of fatigue test data. [ABSTRACT FROM AUTHOR]

Based on the idea that the fatigue damage is caused by the cyclic damage strain, a concept of the critical damage quantity is introduced and a new three-parameter model is developed. The model contains three material performance parameters, i.e., the fatigue ductility coefficient, the fatigue ductility exponent, and the theoretical strain endurance limit. The fatigue ductility coefficient reflects the existence of the critical damage quantity. The fatigue ductility exponent shows the damage resistance ability of the material. And the theoretical strain endurance limit represents the existence of the critical cyclic strain. By using the proposed model, the fatigue crack initiation life of metallic materials can be predicted. [ABSTRACT FROM AUTHOR]

In this article, cyclic hardening/softening behaviors of metallic materials are studied by using 40 alloys’ test results. In the analysis, two parameters are introduced: one parameter is new fracture ductility parameter; the other is cyclic hardening/softening factor. The new fracture ductility parameter expresses cyclic hardening/softening. According to the criterion, there are three critical values—2, 20, and 65.4%. When the new fracture ductility parameter is smaller than 2%, or ranges from 20% to 65.4%, the alloy behaves in a cyclic softening manner. However, when the new fracture ductility parameter ranges from 2% to 20%, or is greater than 65.4%, the alloy behaves in a cyclic hardening manner. The cyclic hardening/softening factor describes the degree of cyclic hardening/softening. If the cyclic hardening/softening factor is greater than 1, the material behaves in a cyclic hardening manner. But if the cyclic hardening/softening factor is smaller than 1, the material behaves in a cyclic softening manner. The more the cyclic hardening/softening factor deviates from 1, the greater the degree of hardening/softening. Compared with the traditional criteria, on the one hand, the present criterion has no indeterminate range, while on the other hand, the cyclic hardening/softening factor quantitatively describes the degree of cyclic hardening/softening. Therefore,the two parameters provide a more descriptive way to describe cyclic hardening/softening behaviors for metallic materials. [ABSTRACT FROM AUTHOR]

The ultimate purpose of the present article is to theoretically estimate the cyclic strength coefficient and the cyclic strain-hardening exponent. For this purpose, the performance parameters of 22 alloys were examined and equations that relate the cyclic strength coefficient and the cyclic strain-hardening exponent to the monotonic tensile ones were developed. Then, by using formulas that express the strength coefficient and the strain-hardening exponent through the four conventional tensile performance parameters, i.e., the yield strength, the ultimate tensile strength, the fracture strength, and the fracture ductility, expressions that describe the cyclic strength coefficient and the cyclic strain-hardening exponent are established. By means of cyclic stress-strain curve, the limitations of the traditional methods of estimating the cyclic strength coefficient and the cyclic strain-hardening exponent are pointed out, and the ability of the new equations at describing the process are established. From the equations the cyclic strength coefficient and the cyclic strain-hardening exponent can be theoretically estimated using the monotonic ones. Furthermore, in the absence of the strength coefficient and the strain-hardening exponent, the cyclic ones can still be obtained from the expressions using the four conventional tensile performance parameters. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is to search formulas for different metals that relate the yield stress-strain with the strength coefficient and the strain-hardening exponent. For this purpose, the test data of nine alloys were used as basic data and the applicability of Hollomon's equation at the yield point of the alloy was studied. This paper explores new equations relating the yield stress-strain with the strength coefficient and the strain-hardening exponent. At the same time, the study introduces a new fracture-ductility parameter. The new fracture-ductility parameter not only describes the applicability of the new equations to these alloys, but may also be better at describing the hardening behavior of a metallic material. [ABSTRACT FROM AUTHOR]

Multi-center studies are advantageous for enrolling participants of varying pathological and demographical conditions, and especially in neurological studies. Hence stability of the obtained quantitative R2* and susceptibility in multicenter studies is a key issue for their widespread applications. In this work, the stabilities of simultaneously obtained R2* and susceptibility are investigated and compared across 10 sites that are equipped with the same scanner and receiver coil, the same post-processing process was used to achieve consistent experiment setup. Two healthy adult volunteers (one male and female) participated in this study. High intraclass correlation coefficient was obtained for both susceptibility (0.94) and R2* (0.96). The coefficients of variance for all measurements obtained were smaller than 0.1, the largest variations of measurements in all the chosen ROIs fall within ±20% from the median value. Higher level of stability was obtained in R2* as compared to susceptibility at 1 mm resolution (P < 0.05) and at 1.5 mm (P < 0.01). [ABSTRACT FROM AUTHOR]