Much previous research has established that perceived ease of use is an important factor influencing user acceptance and usage behavior of information technologies. However, very little research has been conducted to understand how that perception forms and changes over time. The current work presents and tests an anchoring and adjustment-based theoretical model of the determinants of system-specific perceived ease of use. The model proposes control (internal and external--conceptualized as computer self-efficacy and facilitating conditions, respectively), intrinsic motivation (conceptualized as computer playfulness), and emotion (conceptualized as computer anxiety) as anchors that determine early perceptions about the ease of use of a new system. With increasing experience, it is expected that system-specific perceived ease of use, while still anchored to the general beliefs regarding computers and computer use, will adjust to reflect objective usability, perceptions of external control specific to the new system environment, and system-specific perceived enjoyment. The proposed model was tested in three different organizations among 246 employees using three measurements taken over a three-month period. The proposed model was strongly supported at all points of measurement, and explained up to 60% of the variance in system-specific perceived ease of use, which is twice as much as our current understanding. Important theoretical and practical implications of these findings are discussed.

/pdf/determinants-of-perceived-ease-of-use-integrating-control-10opxseq0g.pdf

Determinants of Perceived Ease of Use: Integrating Control, Intrinsic Motivation, and Emotion into the Technology Acceptance Model

As they travel through space, some light beams rotate. Such light beams have angular momentum. There are two particularly important ways in which a light beam can rotate: if every polarization vector rotates, the light has spin; if the phase structure rotates, the light has orbital angular momentum (OAM), which can be many times greater than the spin. Only in the past 20 years has it been realized that beams carrying OAM, which have an optical vortex along the axis, can be easily made in the laboratory. These light beams are able to spin microscopic objects, give rise to rotational frequency shifts, create new forms of imaging systems, and behave within nonlinear material to give new insights into quantum optics.

/pdf/orbital-angular-momentum-origins-behavior-and-applications-1sv8qfuhrs.pdf

Orbital angular momentum: origins, behavior and applications

Researchers interested in emotion have long struggled with the problem of how to elicit emotional responses in the laboratory. In this article, we summarise five years of work to develop a set of films that reliably elicit each of eight emotional states (amusement, anger, contentment, disgust, fear, neutral, sadness, and surprise). After evaluating over 250 films, we showed selected film clips to an ethnically diverse sample of 494 English-speaking subjects. We then chose the two best films for each of the eight target emotions based on the intensity and discreteness of subjects' responses to each film. We found that our set of 16 films successfully elicited amusement, anger, contentment. disgust, sadness, surprise, a relatively neutral state, and, to a lesser extent, fear. We compare this set of films with another set recently described by Philippot (1993), and indicate that detailed instructions for creating our set of film stimuli will be provided on request.

Emotion elicitation using films

Pain interrupts and demands attention. The authors review evidence for how and why this interruption of attention is achieved. The interruptive function of pain depends on the relationship between pain-related characteristics (e.g., the threat value of pain) and the characteristics of the environmental demands (e.g., emotional arousal). A model of the interruptive function of pain is developed that holds that pain is selected for action from within complex affective and motivational environments to urge escape. The implications of this model for research and therapy are outlined with an emphasis on the redefinition of chronic pain as chronic interruption.

https://interruptions.net/literature/Eccleston-PB99.pdf

Pain demands attention: a cognitive-affective model of the interruptive function of pain.

Recent news coverage on pricing portrays the importance of price fairness. This article conceptually integrates the theoretical foundations of fairness perceptions and summarizes empirical findings on price fairness. The authors identify research issues and gaps in existing knowledge on buyers’ perceptions of price fairness. The article concludes with guidelines for managerial practice.

The Price Is Unfair! A Conceptual Framework of Price Fairness Perceptions

An experimental investigation

In the present study, deformation, interaction and freezing during substrate impact of molten droplets in plasma spray processes are numerically investigated. The numerical simulation is conducted on the basis of the full Navier-Stokes equations and the volume of fluid (VOF) function by using a two-domain method for the thermal field and freezing problem and a two-phase flow continuum model for the flow problem with a growing solid layer. Important processing parameters, such as droplet temperature, substrate temperature and droplet velocity are considered and their effects on flattening and freezing are discussed. The numerical results reveal that a droplet spreads and solidifies into a splat of diameter 1.6 to 3.8 times the initial droplet diameter within a time of 0.12 to 0.44 mu s. The droplet liquid separates from the solid/liquid interface when freezing occurs. Increasing initial droplet velocity and enhancing substrate temperature can significantly enhance the flattening extent of droplet. A fully liquid droplet impinging on a solid substrate may generate good contact between the splat and the substrate; a fully liquid droplet striking on another flattening splat produces ejection of the liquid; a fully liquid ring colliding with a flattening splat causes bounce of the liquid and formation of voids. A combination of a liquid droplet condition at a high initial velocity with a semi-solid or solid surface condition may produce good adhesion in sprayed deposits or coatings.

http://iopscience.iop.org/article/10.1088/0022-3727/26/11/010/pdf

Numerical simulation of substrate impact and freezing of droplets in plasma spray processes

Numerical modeling of deformation and interaction of molten tungsten, nickel and titanium droplets impinging on a non-flat surface during thermal spraying has been performed in the present study. This research represents a significant advance relative to earlier published theoretical and numerical studies which were limited to a flat surface. Under the practical conditions in thermal spray processes, the complex physical phenomena of droplet spreading and consolidation take place at a microscopically rough and non-flat surface on a target substrate. The present study, therefore, provides a novel approach to the practical impingement behavior of molten droplets. On the basis of the present study, some fundamental mechanisms governing pore formation in spray processed materials may be established and the concomitant effects of important processing parameters may be determined.

Modeling of molten droplet impingement on a non-flat surface

An existing model has been modified to explore the deformation and solidification of a single droplet impinging on a substrate. The modification accounts for possible solid fraction of material at impact. Numerical results predict that the kinetic energy dominates the process at impinging velocities greater than about 100 m s−1. In addition, the thermal diffusivity of the solidifying material controls the process, but the temperature of the substrate relative to the melting temperature of the material must be considered when comparing materials. It is believed that droplets solidifying into thinner, wider discs would reduce porosity; therefore, dense materials accelerated to high speed would solidify into masses with the highest bulk density.

Numerical analysis of the deformation and solidification of a single droplet impinging onto a flat substrate

Thermal spraying has been widely applied to process thin protective coatings on preshaped parts and to manufacture metallic preforms of a variety of geometries. The quality of materials produced by thermal spraying depends critically on the impact conditions of the droplets. In the present study, the deformation behavior and interaction of molten droplets impinging onto a flat substrate during thermal spraying have been numerically simulated. The calculated results reveal that a droplet spreads uniformly in the radial direction during impingement and eventually forms a thin splat with final diameter and thickness up to 11.3 times and down to 0.02 times the impact diameter, respectively. The final splat diameter increases rapidly with increasing impact velocity and melt density or decreasing melt viscosity. For the processing conditions of interest, the final splat diameter and the spreading time may be approximated by correlations: ds/do = l.04Re0.2 and ts/(do/uo) = 0.62Re0.2, where ds/do is the dimensionless splat diameter; ts/(do/uo) is the dimensionless spreading time; and Re is the Reynolds number. A fully liquid droplet impinging onto a flat solid substrate leads to good contact between the splat and the substrate. Multiple fully liquid droplets striking simultaneously onto other flattening, fully liquid splats cause ejection and rebounding of the liquid, as well as formation of voids within the liquid.

Huimin Liu

Papers

An experimental investigation

Numerical simulation of substrate impact and freezing of droplets in plasma spray processes

Modeling of molten droplet impingement on a non-flat surface

Numerical analysis of the deformation and solidification of a single droplet impinging onto a flat substrate

Numerical simulation of impingement of molten Ti, Ni, and W droplets on a flat substrate