Softmax Dissection: Towards Understanding Intra- and Inter-class Objective for Embedding Learning

The softmax loss and its variants are widely used as objectives for embedding learning, especially in applications like face recognition. However, the intra- and inter-class objectives in the softmax loss are entangled, therefore a well-optimized inter-class objective leads to relaxation on the intra-class objective, and vice versa. In this paper, we propose to dissect the softmax loss into independent intra- and inter-class objective (D-Softmax). With D-Softmax as objective, we can have a clear understanding of both the intra- and inter-class objective, therefore it is straightforward to tune each part to the best state. Furthermore, we find the computation of the inter-class objective is redundant and propose two sampling-based variants of D-Softmax to reduce the computation cost. Training with regular-scale data, experiments in face verification show D-Softmax is favorably comparable to existing losses such as SphereFace and ArcFace. Training with massive-scale data, experiments show the fast variants of D-Softmax significantly accelerates the training process (such as 64x) with only a minor sacrifice in performance, outperforming existing acceleration methods of softmax in terms of both performance and efficiency.Comment: Accepted to AAAI-2020, Oral presentatio

Experimental Investigation on the Mechanical Performance of Steel-ECC Composite Girders with Corrugated Webs under Negative Moment

In order to improve the cracking performance in the negative moment region of composite continuous girder bridges with corrugated webs, engineered cementitious composite (ECC) is used instead of conventional normal concrete (NC). Web and concrete types are used as the main research parameters in experiments. The test results indicate that steel-ECC specimens have a higher flexural load capacity and stiffness than steel-NC specimens. The cracks of steel-ECC specimens are characterised by small width and dense distribution. Nonlinear finite element models are established and verified by experimental results. The simulated load–displacement curves are similar to the experimental ones, and the models have a high degree of accuracy. The ECC slab strength, thickness and width are used as parameters for the investigation to analyse the effect of the ECC slab on the flexural bearing capacity of composite girders. Compared with the results of calculations according to the code, the bearing capacity obtained from the parametric analysis is higher. It suggests that the contribution of the ECC slab needs to be considered when calculating the bearing capacity of the steel-ECC composite girder with corrugated webs

A Cognition Knowledge Representation Model Based on Multidimensional Heterogeneous Data

The information in the working environment of industrial Internet is characterized by diversity, semantics, hierarchy, and relevance. However, the existing representation methods of environmental information mostly emphasize the concepts and relationships in the environment and have an insufficient understanding of the items and relationships at the instance level. There are also some problems such as low visualization of knowledge representation, poor human-machine interaction ability, insufficient knowledge reasoning ability, and slow knowledge search speed, which cannot meet the needs of intelligent and personalized service. Based on this, this paper designs a cognitive information representation model based on a knowledge graph, which combines the perceptual information of industrial robot ontology with semantic description information such as functional attributes obtained from the Internet to form a structured and logically reasoned cognitive knowledge graph including perception layer and cognition layer. Aiming at the problem that the data sources of the knowledge base for constructing the cognitive knowledge graph are wide and heterogeneous, and there are entity semantic differences and knowledge system differences among different data sources, a multimodal entity semantic fusion model based on vector features and a system fusion framework based on HowNet are designed, and the environment description information such as object semantics, attributes, relations, spatial location, and context acquired by industrial robots and their own state information are unified and standardized. The automatic representation of robot perceived information is realized, and the universality, systematicness, and intuition of robot cognitive information representation are enhanced, so that the cognition reasoning ability and knowledge retrieval efficiency of robots in the industrial Internet environment can be effectively improved

Research on the Shear Behaviour of Composite Shear Connectors

In order to make full use of the advantages of welded stud and perfobond rib shear connectors, a new type of composite shear connector is proposed. Studs are welded to the perforated steel plate of the PBL connectors. Six specimens were designed and tested to investigate the shear behaviour of the composite connectors. The effects of the hole number, welded stud number, and end-bearing modes on the shear behaviour of the composite connectors were discussed. In addition, the composite connectors were compared with the conventional welded stud and perfobond rib connectors to analyse the difference in shear performance. The composite connectors’ shear behaviours are significantly better than those of welded stud connectors and PBL connectors. The experimental results show that increasing the number of welded studs and perforated holes and end-bearing concrete can significantly improve the shear performance of composite connectors. Secondly, a finite element model was established considering the nonlinearity of the structure and was validated based on the experimental results. Finally, the effects of reinforcement diameter, welded stud diameter, and concrete strength on the shear performance of composite connectors were analysed. The shear resistance increases as the penetrating rebar diameter, welded stud diameter, and concrete strength increase. Moreover, the overall damage level of the concrete can be significantly affected

Research on the Shear Behaviour of Composite Shear Connectors

In order to make full use of the advantages of welded stud and perfobond rib shear connectors, a new type of composite shear connector is proposed. Studs are welded to the perforated steel plate of the PBL connectors. Six specimens were designed and tested to investigate the shear behaviour of the composite connectors. The effects of the hole number, welded stud number, and end-bearing modes on the shear behaviour of the composite connectors were discussed. In addition, the composite connectors were compared with the conventional welded stud and perfobond rib connectors to analyse the difference in shear performance. The composite connectors’ shear behaviours are significantly better than those of welded stud connectors and PBL connectors. The experimental results show that increasing the number of welded studs and perforated holes and end-bearing concrete can significantly improve the shear performance of composite connectors. Secondly, a finite element model was established considering the nonlinearity of the structure and was validated based on the experimental results. Finally, the effects of reinforcement diameter, welded stud diameter, and concrete strength on the shear performance of composite connectors were analysed. The shear resistance increases as the penetrating rebar diameter, welded stud diameter, and concrete strength increase. Moreover, the overall damage level of the concrete can be significantly affected

Synthesis and Evaluation of LaBaCo_2−<i>x</i>Mo<i>_x</i>O_5+<i>δ</i> Cathode for Intermediate-Temperature Solid Oxide Fuel Cells

LaBaCo2−xMoxO5+δ (LBCMx, x = 0–0.08) cathodes synthesized by a sol-gel method were evaluated for intermediate-temperature solid oxide fuel cells. The limit of the solid solubility of Mo in LBCMx was lower than 0.08. As the content of Mo increased gradually from 0 to 0.06, the thermal expansion coefficient decreased from 20.87 × 10−6 K−1 to 18.47 × 10−6 K−1. The introduction of Mo could increase the conductivity of LBCMx, which varied from 464 S cm−1 to 621 S cm−1 at 800 °C. The polarization resistance of the optimal cathode LBCM0.04 in air at 800 °C was 0.036 Ω cm2, reduced by a factor of 1.67 when compared with the undoped Mo cathode. The corresponding maximum power density of a single cell based on a YSZ electrolyte improved from 165 mW cm−2 to 248 mW cm−2 at 800 °C

Minor Ag induced shear performance alternation in BGA structure Cu/SnBi/Cu solder joints under electric current stressing

In this work, the effect of minor Ag addition on shear performance of ball grid array (BGA) structure Cu/SnBi/Cu solder joints under electric current stressing was investigated. The results show that the shear strength of solder joints decreased with increasing current density, and the effect of Ag addition on shear strength changed from an elevating state to a deteriorating state. The elevating effect of Ag addition was due to the dominance of Sn/Bi phase refinement and Ag3Sn dispersion, which was weakened gradually with the increase in current density. The deteriorating effect of Ag addition was attributed to the more inhomogeneous distribution of current density and higher thermal gradient induced by the finer phase of the solder matrix as well as the consequent severer strain mismatch at the Sn/Bi phase interface. The finer Sn/Bi phase was also conductive to easier lattice atom migration under current stressing, resulting in a rapid decrease in shear strength. Moreover, the dominant factor on the shear strength reduction tended to change from Joule heating to athermal effect of current stressing. The fracture of solder joints indicated an insignificant influence by the Ag addition, which all occurred in the solder matrix in a ductile mode

Improvement of Solder Joint Shear Strength under Formic Acid Atmosphere at A Low Temperature

With the continuous reduction of chip size, fluxless soldering has brought attention to high-density, three-dimensional packaging. Although fluxless soldering technology with formic acid (FA) atmosphere has been presented, few studies have examined the effect of the Pt catalytic, preheating time, and soldering pad on FA soldering for the Sn-58Bi solder. The results have shown that the Pt catalytic can promote oxidation–reduction and the formation of a large pore in the Sn-58Bi/Cu solder joint, which causes a decrease in shear strength. ENIG (electroless nickel immersion gold) improves soldering strength. The shear strength of Sn-58Bi/ENIG increases under the Pt catalytic FA atmosphere process due to the isolation of the Au layer on ENIG. The Au layer protects metal from corrosion and provides a good contact surface for the Sn-58Bi solder. The shear strength of the Sn-58Bi/ENIG joints under a Pt catalytic atmosphere improved by 44.7% compared to using a Cu pad. These findings reveal the improvement of the shear strength of solder joints bonded at low temperatures under the FA atmosphere

Regularization Penalty Optimization for Addressing Data Quality Variance in OoD Algorithms

Due to the poor generalization performance of traditional empirical risk minimization (ERM) in the case of distributional shift, Out-of-Distribution (OoD) generalization algorithms receive increasing attention. However, OoD generalization algorithms overlook the great variance in the quality of training data, which significantly compromises the accuracy of these methods. In this paper, we theoretically reveal the relationship between training data quality and algorithm performance, and analyze the optimal regularization scheme for Lipschitz regularized invariant risk minimization. A novel algorithm is proposed based on the theoretical results to alleviate the influence of low quality data at both the sample level and the domain level. The experiments on both the regression and classification benchmarks validate the effectiveness of our method with statistical significance

Cfr-mediated linezolid-resistance among methicillin-resistant coagulase-negative staphylococci from infections of humans.

Four methicillin-resistant coagulase-negative staphylococci (MRCoNS), one Staphylococcus haemolyticus and three Staphylococcus cohnii, from infections of humans collected via the Ministry of Health National Antimicrobial Resistance Surveillance Net (Mohnarin) program in China were identified as linezolid-resistant. These four isolates were negative for the 23S rRNA mutations, but positive for the gene cfr. Mutations in the gene for the ribosomal protein L3, which resulted in the amino acid exchanges Gly152Asp and Tyr158Phe, were identified in S. haemolyticus 09D279 and S. cohnii NDM113, respectively. In each isolate, the cfr gene was located on a plasmid of ca. 35.4 kb, as shown by S1 nuclease pulsed-field gel electrophoresis and Southern blotting experiments. This plasmid was indistinguishable from the previously described plasmid pSS-02 by its size, restriction pattern, and a sequenced 14-kb cfr-carrying segment. Plasmid pSS-02 was originally identified in staphylococci isolated from pigs. This is the first time that a cfr-carrying plasmid has been detected in MRCoNS obtained from intensive care patients in China. Based on the similarities to the cfr-carrying plasmid pSS-02 from porcine coagulase-negative staphylococci, a transmission of this cfr-carrying plasmid between staphylococci from pigs and humans appears to be likely