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A good laser texture design in hard disk landing zone can significantly reduce the slider-disk contact force, contact time and contact frequency during a slider's contact start and stop process. In this paper a numerical investigation was conducted on the effects of laser texture properties, disk topography and slider design on the dynamic characteristics of a Pico slider during its take-off in the landing zone. Factors considered in this study are bump height, bump diameter, bump density, slider crown, spin acceleration, and waviness. The slider contact take-off process was simulated with various values of those factors, and the results were analyzed through comparing the contact frequency, contact force, contact time, and take-off speed. The simulation results show that a regular take-off is not a continuous contact process, but composed of periodical contact bursts, and the time duration of each group of contact bursts is about the same. It has been found that some of the laser texture properties can significantly influence the slider's take-off characteristics. Properly choosing laser texture design parameters can reduce the impacts between slider and bumps during the take-off process. IntroductionAlmost all slider/disk wear and debris buildup occur during the contact start/stop (CSS) process. Slider-disk impacts during this process play a very important role in slider/disk wear. Increasing the slider take-off stability and reducing the impacts can significantly increase the slider/ disk interface durability. A good understanding of slider/ disk interaction during CSS process can improve the laser texture design in the landing zone to minimize the slider and disk surface wear. Benson et al. (1989) studied the dynamics of slider bearings during contacts. Ono et al.(1995) developed a new theoretical approach by using single-degree-of-freedom slider and suspension model to simulate the dynamic contact behavior. Leo et al. (1995) studied the slider/disk interaction during the landing process. They provided a theoretical model that includes more rigorous surface characterization, the statistical nature of summit interaction, and nonlinear rarefaction effects in the modified Reynolds equation. Hu et al. (1998) studied the effects of laser textured disk surface on a slider's flying characteristics for two types of bumps. However, no study has been found that conducted a comprehensive investigation on the slider's flying characteristics during the CSS process and the influence of the laser texture designs.Our CSS tests show that under the same lubrication and test condition, disks of different laser texture designs have different results, which means that different laser texture designs change the flying dynamics. Bad laser texture design causes harder and more impacts during the take-off and landing process of a slider. To simulate a CSS process incorporating the effects of lubricant is extremely difficult. Kato et al. (2000) investigated the dynamic characteristics of an in-contact disk-slider taking into acc...

Online-learning stress poses a significant challenge to the sustainability of higher education. The present study employs mixed methods to propose a conceptual process model that depicts the mechanism of online-learning stress of college students. The result of the qualitative study indicates 11 influential factors of online-learning stress, 10 manifestations of online-learning stress (OS), and three learning performance outcomes of OS (LP) through in-depth interviews with 15 college students. The result of a quantitative study on 159 online surveys implies that the influential factors of online-learning stress could be further categorized into learner competence and commitment (LC), course design reasonability (CD), and social support (SS). In addition, the results of the structural equation model (SEM) confirm the negative impact of LC and CD on OS, as well as OS on LP. However, the negative effect of SS on OS is unsupported. The study contributes to both OS theory development and online-learning and teaching in higher education.