This article proposes an LED driver circuit which is wide-range continuous dimmable for high power lighting application. The proposed LED driver is based on single-inductor-multiple-output (SIMO) dc-dc converter. A pulsewidth modulation (PWM) control strategy is applied on the LED driver to control the brightness of LEDs flexibly and precisely, with which the dimming frequency can be increased significantly, and the dimming ratio for all branches can be adjusted separately. PWM dimming would cause the inductor current overshooting when dimming switch alters from off to on, which makes the LED current varying. To suppress the inductor current overshooting, a sampling-holding circuit is adopted in the feedback loop of the proposed LED driver. A prototype of the proposed LED driver is fabricated and tested. The measurement results show that the dimming frequency can be increased to 10 kHz, the dimming ratio can be set from 5% to 100% with a minimum pulsewidth of 5 μs, and the inductor current overshooting is suppressed from 150% to approximately 0%. The proposed LED driver can output more than 80 W and achieve a conversion efficiency of 97%.

Silicon Carbide (SiC) Ultraviolet (UV) phototransistors with bidirectional bias response were fabricated and analyzed in this letter. The results showed that the fabricated UV phototransistor exhibited stable photoelectric response characteristics and transistor characteristics under both forward and reverse voltages, owing to the structure design of the epi-layers, while the mechanism of the bidirectional response was also studied. The difference in photocurrent under different bias voltages and wavelengths of UV illumination were mainly due to the variation of the absorption coefficient with wavelength and the change in the width of the space charge regions, which ultimately led to a difference in the number of photo-generated carriers. The time response characteristics of the detector showed that there were time delays when the detector was turned on and turned off, which was caused by the photo minority carriers in the depletion layer of the base-collector junction.

A novel 4H-SiC multizone collector vertical insulated-gate bipolar transistor (MZC-IGBT) with an alternate P⁺/P⁻/P⁺ multizone structure in the collector region is proposed and investigated by numerical simulations in this article. Comparing with conventional 4H-SiC IGBTs, lower potential barrier regions are formed in the proposed MZC-IGBT at the interface between the N field-stop buffer and the collector region, modifying the carrier extraction effect to a proper level and resulting in a superior tradeoff between the static and dynamic performances. The proposed device consumes less energy in a wide frequency range. The numerical simulation reveals that the average dissipation power of the optimized 4H-SiC MZC-IGBT can be decreased by 63.1% at a high frequency of 20 kHz and even 2.26% at a low frequency of 500 Hz, which makes the proposed device much more suitable for high-frequency applications.

Purpose: Middle-aged and elderly users become an important group on short-video platforms, however, the research on determinants of their video-creating intention is limited. Based on lifespan development theories, this study examines the impact of aging experiences on their video-creating intention, considering internal generative motivations as mediators and age as a moderator.Design/methodology/approach: To test this study’s hypotheses, survey data from 321 Chinese middle-aged and elderly short-video users were collected and partial least square-structural equation modelling (PLS-SEM) approach was used to analyze these data.Findings: Middle-aged and elderly users' aging experiences of social loss and personal growth are positively related to their video-creating intention. Aging experiences (i.e. physical loss, social loss, and personal growth) are positively related to internal generative motivations (i.e. need to be needed and symbolic immortality), and need to be needed is positively related to video-creating intention. Via the mediation of need to be needed, physical loss and personal growth are indirectly positively related to video-creating intention. Personal growth strengthens the relationship between physical loss and symbolic immortality, but weakens the associations of social loss with need to be needed and symbolic immortality. Age weakens the relationship between symbolic immortality and video-creating intention.Originality/value: This study is the first wave to introduce and integrate lifespan theories such as selective optimization with compensation model, socioemotional selectivity theory, and generativity theory to explore the impacts of aging experiences on middle-aged and elderly users' video-creating intention by considering generativity motivations as mediators and age as a moderator.