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Online task-oriented check-ins (i.e. OTOCs) are popular means of tracking personal progress in certain fields. This study focused on the use of OTOC platforms and explored the predictors of individuals' continuing usage intention.

A model was proposed to understand Chinese users' continuous intention of OTOCs based on the UTAUT framework. Perceived social presence was also incorporated as a predictor of continuance intention of OTOC platforms. A survey of 397 users of the OTOC platforms was conducted in Nanjing, China.

Performance expectancy, hedonic motivation, and habit had direct, positive influence on the continuous use intention, whereas effort expectancy and social influence were not significant predictors of continuance intention of OTOCs. Perceived social presence was a significant, indirect predictor of intention to continuously use the OTOCs, and the relationship was mediated by performance expectancy, hedonic motivation, and habit.

This study distinguished OTOCs from other modes of self-tracking and extended the UTAUT framework by incorporating perceived social presence as a predictor of continuous technology use in the context of OTOCs. This study also provided a deeper understanding of the interrelations between the explanatory variables of the model that have been identified as robust in previous literature on technology use.

The modern missile has low uncertain and wide range vibration frequency. The conventional notch filter with the fixed notch frequency is less effective than that of the adaptive notch filter (ANF) in vibration suppression for the time-varying vibration frequency.

To overcome the drawback, a novel method is based on frequency estimators made by interpolation of three discrete Fourier transform (DFT) spectral lines. The modified frequency estimators based on the interpolation of three DFT spectral lines are presented to identify and track the vibration frequency. Then the notch frequencies of multiple ANFs are real-timely tuned according to estimators.

Finally, taking the second-order flexible missile as an example, the performance of the proposed method is verified. The verified simulation results show that multiple ANFs are effective in vibration suppression.

Cascading multiple ANFs to achieve multi-order vibration suppression is more efficient and feasible than conventional fixed-parameter notch filtering.

The frequency estimation method based on three DFT spectral lines proposed in this paper can effectively identify and track signals in the noise environment. Compared with conventional methods, the method pretended in this paper has high identification accuracy and a stronger ability to track signals. It can meet the fast frequency identification requirements of the actual flexible missile.

Structural color is more brilliant in color, more resistant to sunshine and will not fade away with time, and more environmental friendly than traditional dyes and pigments. The purpose of this paper is to prepare structural colors of fabrics coated with Ag/TiO₂ composite films by magnetron sputtering, and analyze the relationship between the colors and the thicknesses of TiO₂ films in Ag/TiO₂ composite films.

Preparation of Ag/TiO₂ composite films by magnetron sputtering and their deposition on textiles were investigated. The chemical compositions and surface morphology of Ag/TiO₂ composite films were examined by X-ray photoelectron spectroscopy and scanning electron microscopy, and the structural color of fabric coated with Ag/TiO₂ composite film was also analyzed.

Ag/TiO₂ composite films deposited on textile substrate exhibited structural colors, and the bright colors could be adjusted and controlled by the thickness of TiO₂ thin films in Ag/TiO₂ composite films without any dyes or pigments. By comparing the results of theoretical calculation and experimental results, it was found that the creation of structural colors by the experiment was coincident to the colors by theoretical calculation according to the film interference principle. There was a linear relationship between the thickness of TiO₂ film and the wavelength of the structural color.

Compared to traditional coloration by dyes or pigments, the coloration of textile by structural color from Ag/TiO₂ composite films prepared by magnetron sputtering was very environmental friendly and simple without water consuming, time consuming and tedious work. Structural colors have great potential applications in textiles in place of traditional dyes and pigments. Furthermore, the textiles coated with Ag/TiO₂ composite films have good electrical, optical and magnetic properties, and can be used in apparel, home furnishings and industrial fabrics.

This study aims to research the time-varying mesh stiffness (TVMS) model for orthogonal face gear drives considering elastohydrodynamic lubrication (EHL) and provide a theoretical basis for understanding the dynamic characteristics of face gear drives.

Considering EHL, a novel model is proposed to calculate the TVMS of orthogonal face gears using the deformation compatibility condition. First, the tooth surface equations of orthogonal face gears are derived according to the tooth surface generation principle. Then, the oil film thickness on the tooth surface of face gears is obtained by solving the governing equations of EHL. Furthermore, the proposed model is used to calculate the TVMS of face gears along the mesh cycle and is verified. Finally, the effects of module, tooth number of shaper cutter and pressure angle on mesh stiffness are analyzed.

The results indicate that when the contact ratio is greater than 1 and less than or equal to 2, the TVMS of face gears exhibits a phenomenon of double-single tooth alternating meshing where sudden changes occur. As the module increases, the overall mesh stiffness of face gears increases, and the magnitude of the sudden change at the moment of single-double tooth alternating meshing gradually increases. As the tooth number of shaper cutter and pressure angle increase, so does the TVMS of face gears. When the effect of oil film is considered, the calculated TVMS of face gears slightly increases overall and the increase in average oil film thickness leads to a rise in the TVMS. This study provides a theoretical basis for understanding the dynamic characteristics of face gear drives.

This study’s originality and value lie in its comprehensive approach, which includes conducting analysis based on loaded tooth contact, considering the influence of elastohydrodynamic lubrication, proposing a novel analytical–finite–element model, calculating TVMS of face gears, verifying the proposed model and analyzing the effects of typical structural parameters and oil film thickness.