From the black box to the glass box: Using unsupervised and supervised learning processes to predict user engagement for the airline companies

Firms collect an enormous amount of user generated content (UGC), such as social media posts, to analyze consumers’ unfiltered opinions regarding brands and firms. A challenge in analyzing unstructured UGC is the lack of analytic frame. By adopting both unsupervised and supervised learning processes for using artificial intelligence (AI), we collected 680,410, tweets related to airline companies (United Airlines, Delta Airlines, Southwest Airlines, Alaska Airlines, and Hawaiian Airlines) and analyzed 4961 retweets to predict user engagement levels on Twitter. Rooted in the electronic word-of-mouth (eWOM) perspective, the results of this study indicated that consumer sentiment was positive for United Airlines, Delta Airlines, and Alaska Airlines, whereas it was negative for Southwest Airlines and Hawaiian Airlines. We also examined the effects of word count, gaps between the tweet generated date and the retweeted date, the number of the hashtag(s), and extracted topics on predicting the level of user engagement. Ultimately, this study provided a detailed guide to mangers on how to use an unstructured data analysis procedure incorporating both supervised and unsupervised learning processes

Diode-less bilayer oxide (WOx-NbOx) device for cross-point resistive memory applications

The combination of a threshold switching device and a resistive switching (RS) device was proposed to suppress the undesired sneak current for the integration of bipolar RS cells in a cross-point array type memory. A simulation for this hybrid-type device shows that the matching of key parameters between switch element and memory element is an important issue. Based on the threshold switching oxides, a conceptual structure with a simple metal-oxide1-oxide2-metal stack was provided to accommodate the evolution trend. We show that electroformed W-NbOx-Pt devices can simultaneously exhibit both threshold switching and memory switching. A qualitative model was suggested to elucidate the unique properties in a W-NbOx-Pt stack, where threshold switching is associated with a localized metal-insulator transition in the NbOx bulk, and the bipolar RS derives from a redox at the tip of the localized filament at the WOx-NbOx interface. Such a simple metal-oxide-metal structure, with functionally separated bulk and interface effects, provides a fabrication advantage for future high-density cross-point memory devices

Highly uniform and reliable resistance switching properties in bilayer WO x/NbO x RRAM devices

Memory performances, especially uniformity and reliability of resistance random access memory (RRAM) devices with W/NbOx/Pt structures were investigated. Scaling down the active device area (φ = 250 nm) can significantly minimize extrinsic defects relat

A Water-Resistant, Self-Healing Encapsulation Layer for a Stable, Implantable Wireless Antenna

Polymers for implantable devices are desirable for biomedical engineering applications. This study introduces a water-resistant, self-healing fluoroelastomer (SHFE) as an encapsulation material for antennas. The SHFE exhibits a tissue-like modulus (approximately 0.4 MPa), stretchability (at least 450%, even after self-healing in an underwater environment), self-healability, and water resistance (WVTR result: 17.8610 g m−2 day−1). Further, the SHFE is self-healing in underwater environments via dipole–dipole interactions, such that devices can be protected from the penetration of biofluids and withstand external damage. With the combination of the SHFE and antennas designed to operate inside the body, we fabricated implantable, wireless antennas that can transmit information from inside the body to a reader coil that is outside. For antennas designed considering the dielectric constant, the uniformity of the encapsulation layer is crucial. A uniform and homogeneous interface is formed by simply overlapping two films. This study demonstrated the possibility of wireless communication in vivo through experiments on rodents for 4 weeks, maintaining the maximum communication distance (15 mm) without chemical or physical deformation in the SHFE layer. This study illustrates the applicability of fluoroelastomers in vivo and is expected to contribute to realizing the stable operation of high-performance implantable devices

Co-occurrence of threshold switching and memory switching in Pt/NbOx/Pt cells for crosspoint memory applications

To integrate bipolar resistive switching cells into crosspoint structures, we serially connect a threshold-switching (TS) Pt/NbO2/Pt device with a memory-switching (MS) Pt/Nb2O5/Pt device and observe the suppression of the undesired sneak current. A simpler Pt/Nb2O5/NbO2/Pt bilayer oxide device was designed; it simultaneously exhibits TS and MS. The unique device characteristics in the metal/oxide/metal structure can be directly integrated into a crosspoint memory array without the diode; this can significantly reduce the fabrication complexity

Improvement of resistive switching uniformity by introducing a thin NbOx interface layer

Uniformity is by far an important issue for the application of resistive random access memory (RRAM). In this letter, we explore a prototype RRAM device for switching uniformity improvement. Compared to W/WO3-x/Pt structure, after the introduction of a thin NbOx film between WO 3-x and Pt bottom electrode, the device exhibits much better resistive hysteresis and switching uniformity. The main composition of the interface layer is NbO2 suboxide showing insulator-metal phase transition. A combined filamentary conduction model is proposed to clarify the role of NbOx layer on the resistive switching stabilization during the forming process

Self-selective characteristics of nanoscale VOx devices for high-density ReRAM applications

We herein present a hybrid-type memory device in which threshold switching and bipolar resistive switching are combined. The nanoscale vanadium oxide (VOx) device simultaneously exhibited self-selective performance and memory switching by electroforming