Knowledge Distillation based Contextual Relevance Matching for E-commerce Product Search

Online relevance matching is an essential task of e-commerce product search to boost the utility of search engines and ensure a smooth user experience. Previous work adopts either classical relevance matching models or Transformer-style models to address it. However, they ignore the inherent bipartite graph structures that are ubiquitous in e-commerce product search logs and are too inefficient to deploy online. In this paper, we design an efficient knowledge distillation framework for e-commerce relevance matching to integrate the respective advantages of Transformer-style models and classical relevance matching models. Especially for the core student model of the framework, we propose a novel method using $k$-order relevance modeling. The experimental results on large-scale real-world data (the size is 6$\sim$174 million) show that the proposed method significantly improves the prediction accuracy in terms of human relevance judgment. We deploy our method to the anonymous online search platform. The A/B testing results show that our method significantly improves 5.7% of UV-value under price sort mode

Compressive performance of AFRP reinforced laminated bamboo stub columns

Engineered bamboo construction can be affected by natural defects, insects, corrosion, etc., which will result in damaging the mechanical properties of structural components. However, traditional reinforcement methods such as setting steel supports and increasing the cross-sectional area of components may cost a lot and cause a negative influence on the appearance of building. Many engineering practices and research works show that applying FRP (Fiber Reinforced Polymer/Fiber) sheet is an economical and efficient method for reinforcing and retrofitting building structures. Therefore, the compressive performance of AFRP (Aramid Fiber Reinforced Polymer/Fiber) reinforced laminated bamboo lumber (LBL) stub columns was studied in this paper. Through six groups (three replicates for each group) of stub columns with six different cloth ratios, the influence of AFRP on the failure pattern and mechanical properties of bamboo columns was explored. The test results showed that AFRP could effectively restrain the lateral deformation and improve the mechanical behavior of LBL columns. With the increase in cloth ratio, the ultimate strength and elastic modulus increased linearly in general, while the Poisson’s ratio gradually decreased. The reduced modulus of reinforced columns in the elastoplastic stage increased up to 161.31% compared with normal columns. Although the ductility of LBL columns laterally wrapped by AFRP was greatly improved, the initial stiffness, yield point and turning points between elastoplastic stage and plastic stage basically remained unchanged in contrast to unreinforced columns. Based on the test results, an empirical equation considering the cloth ratio was proposed to calculate the ultimate strength of AFRP reinforced LBL columns, using ‘Lam and Teng’ model. In addition, a simplified equation was also proposed to calculate the compressive strength of reinforced LBL columns derived from Mises yield criterion. The results of this work can be a reference to promote the application of strengthening and retrofitting engineered bamboo structure with FRP

Bamboo node effect on the tensile properties of side press-laminated bamboo lumber

At present, most of the existing studies on bamboo nodes focus on the raw bamboo. There is still a lack of researches on the nodes in side press-laminated bamboo lumber (LBL). However, after processing, bamboo nodes in the laminated bamboo lumber are different from the raw bamboo nodes in terms of performance. Therefore, this paper carried out tests to analyze the influence of bamboo node on the tensile properties parallel to grain of side press-laminated bamboo lumber. A total of 180 specimens were divided into six groups, and the number and position of the bamboo nodes at the specimen in each group were different. The effects of these factors on the strength, elastic modulus, and Poisson’s ratio of the side press-laminated bamboo lumber under tension parallel to grain were obtained. The tensile failure of side press-laminated bamboo lumber was a brittle fracture, and the typical failure mode can be classified into three types. The mean value for tensile strength was 127.18 MPa when there was no bamboo node, while the mean value was 89.99–107.37 MPa when there were one to three bamboo nodes. The number of bamboo nodes would significantly affect the tensile properties parallel to grain of side press-laminated bamboo lumber, whereas the position of bamboo nodes has an insubstantial impact. Comparisons with other research results were also carried out. A series of formulas were proposed based on the test results to reflect how the node influenced the mechanical properties of side press LBL under tensile conditions

Length effect on bending properties and evaluation of shear modulus of parallel bamboo strand lumber

One hundred sixty-two parallel bamboo strand lumber (PBSL) beams were tested for the bending properties under three-point bending with variable span. Two typical failure types were classified, type I was tension failure of the bamboo fiber located below the neutral axis at mid-span, while type II was shear failure which was mainly found in specimens with large depth-span ratio. The shear modulus G LR of PBSL was also calculated according to Timoshenko’s bending theory. To evaluate the shear modulus, 45° off-axis compression tests had been done. The results showed that the mean values of shear modulus for G LT, G TR, and G LR are 1254.5 MPa, 408.1 MPa, and 716.4 MPa, respectively. The bending test result was compared with the shear modulus measured by 45° off-axis compression test. It was found that the shear modulus measured by three-point bending test with variable span was significantly less than the shear modulus obtained by 45° off-axis compression test. The empirical equation of shear factor s corresponding to depth-span ratio h/l was proposed. The calculation results gained from the proposed formula are in good agreement with the 45° off-axis compression test results

Boron and Phosphorus Co-Doped Graphitic Carbon Nitride Cooperate with Bu₄NBr as Binary Heterogeneous Catalysts for the Cycloaddition of CO₂ to Epoxides

The development of a cost-effective heterogeneous catalytic system for the cycloaddition reaction of CO2 and epoxides is of great importance. In this manuscript, three kinds of boron and phosphorus co-doping graphitic carbon nitride (BP-CN) were prepared and characterized. Among them, BP-CN-1 displayed the optimal catalytic performance in the presence of Bu4NBr (tetrabutylammonium bromide) for the CO2 cycloaddition with propylene oxide, and 95% propylene carbonate yield was obtained under a 120 °C, 2 MPa, 6 h condition. Moreover, the BP-CN-1/Bu4NBr catalytic system is compatible with various epoxides and also exhibits excellent recycling performance under metal- and solvent-free conditions. Hence, BP-CN-1 exhibited an attractive application for the efficient fixation of CO2 due to the simple, eco-friendly synthesis route and effective catalytic activity

Factors Influencing Recognition Capability of Inverse Opal Structured Photonic Crystal Sensors

Nowadays, many kinds of colloidal photonic crystal (PC) sensors with inverse opal (IO) structures have been developed. However, there are few systematic studies on the factors influencing their recognition capability and responsiveness capability. In this paper, the relationships between recognition capability of IO structured PC sensors and all the parameters in Bragg–Snell’s law have been explored. In addition, research on the recognition ability of PC sensors typically focuses only on the refractive index difference between the identified substances. Herein, we define two concepts, namely the absolute refractive index difference and the relative refractive index difference, and prove that the recognition ability not only relies on the absolute refractive index between the identified substances, but also on the relative refractive index. Bragg–Snell’s law analysis confirms that the responsiveness capability is directly proportional to the void size of the IO structure, which is also confirmed by the finite difference time domain (FDTD) method. It is believed that these systematic studies have important guiding significance for creating advanced IO structured PC sensors

Factors Influencing Recognition Capability of Inverse Opal Structured Photonic Crystal Sensors

Nowadays, many kinds of colloidal photonic crystal (PC) sensors with inverse opal (IO) structures have been developed. However, there are few systematic studies on the factors influencing their recognition capability and responsiveness capability. In this paper, the relationships between recognition capability of IO structured PC sensors and all the parameters in Bragg–Snell’s law have been explored. In addition, research on the recognition ability of PC sensors typically focuses only on the refractive index difference between the identified substances. Herein, we define two concepts, namely the absolute refractive index difference and the relative refractive index difference, and prove that the recognition ability not only relies on the absolute refractive index between the identified substances, but also on the relative refractive index. Bragg–Snell’s law analysis confirms that the responsiveness capability is directly proportional to the void size of the IO structure, which is also confirmed by the finite difference time domain (FDTD) method. It is believed that these systematic studies have important guiding significance for creating advanced IO structured PC sensors

Host relationships and biological notes of Cassidinae beetles (Coleoptera, Chrysomelidae) in Qiannan Prefecture, Guizhou, China

The faunal composition, host relationships and biological information of the subfamily Cassidinae (Coleoptera, Chrysomelidae) remain poorly known in many Chinese regions. Based on the seven-year field survey, faunal composition and host associations of Cassidinae beetles were systematically compiled for Qiannan Buyi and Miao Autonomous Prefecture, Guizhou Province. In particular, through direct field observations, detailed biological information, such as life history and behavioural features and host plants were first recorded for 56 species of Cassidinae beetles. We have tripled the number of Cassidinae species in Qiannan. Sixty-nine species of Cassidinae beetles belonging to 17 genera and eight tribes were identified, of which 38 species are newly recorded in Guizhou and 56 are newly recorded in Qiannan. The tribes Leptispini and Notosacanthini were newly recorded in Guizhou. The genera Thlaspidosoma Spaeth, Downesia Baly, Klitispa Uhmann, Platypria Guérin-Méneville, Leptispa Baly and Notosacantha Chevrolat were recorded in Guizhou for the first time. A total of 61 species, 37 genera and 17 families of host plants were collected. Lardizabalaceae and Araliaceae were new host plant families for Cassidinae worldwide. Quantitative food web analysis indicated that Cassidinae species in Qiannan mainly feed on Poaceae, Rosaceae, Convolvulaceae and Lamiaceae. Callispini and Leptispini only feed on monocots, Aspidimorphini, Basiprionotini, Cassidini and Notosacanthini only feed on dicots, while Hispini feed on both monocots and dicots. The feeding patterns and corresponding damage marks of Cassidinae were quite diverse. In addition, the pupal mine-making behaviour of Dactylispa excisa (Kraatz, 1879), D. similis Chen et T’an, 1985 and D. uhmanni Gressitt, 1950 are worth further study. Although preliminary, our field survey is an essential step in understanding Cassidinae behaviour and Cassidinae-plant interactions