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To get rid of the limitations of traditional keyboards, we report a new generation wearable keyboardless input system (WKIS). Based on the coupling of triboelectrification and electrostatic induction, the single-electrode mode triboelectric nanogenerator (TENG) worn on the five fingers can convert finger tapping into electrical signals. Meanwhile, by developing a number pair coding table in vowel mode, we integrated the 26 English letters and necessary instructions into WKIS with five-finger tapping. The main body of the device is an ultra-thin silk fibroin film (SF), which is biocompatible, water-permeable, breathable and skin conformal, enabling it suitable for long-term wear as a ring on the finger. Data coding and transmission process are completed through a printed circuit board (PCB) and Wi-Fi module to realize keyboard communication. Feature engineering and machine learning are employed to identify WKIS registered users with an accuracy of 92%. In addition, the WKIS provides an effective solution in smart home control, which has potential applications in future human-computer interaction, Internet of Things and VR scenarios. [Display omitted] • Biocompatible, water/air permeable and ultra-thin triboelectric nanogenerator (TENG) based on silk fibroin film (SF) is fabricated. • Unique vowel mode input method is developed to integrate 26 English letters and necessary instructions into wearable keyboard with five-finger tapping. • Human-computer interaction and private information protection are realized by a printed circuit board, Wi-Fi module and machine learning. [ABSTRACT FROM AUTHOR]

The research presents an input method to estimate the unknown time-varying strength on the sources of a primer applied at this on-line inverse heat conduction problem. We use the input method to recursively predict both the impulse strength acting on the front of thin copper foil and the transient temperature-time curves from the thin copper foil with the rapid combustion of different charge designs for primers. The input method includes the extended Kalman filter and weighted recursive least squares estimator. The purpose of the extended Kalman filter is to generate the recursive innovation sequence and the weighted recursive least squares estimator is used to identify the unknown time-varying strength. The results of simulation and experiment show that the input method can estimate the unknown time-varying heat flux on-line with more accuracy in the inverse heat conduction problem mode. The test experiments, namely different conductive thickness designs for primers with time-varying heat flux input, are solved to illustrate the effectiveness and good accuracy of the presented method. [ABSTRACT FROM AUTHOR]