Low Mach number limit for non-isentropic magnetohydrodynamic equations with ill-prepared data and zero magnetic diffusivity in bounded domains

In this article, we verify the low Mach number limit of strong solutions to the non-isentropic compressible magnetohydrodynamic equations with zero magnetic diffusivity and ill-prepared initial data in three-dimensional bounded domains, when the density and the temperature vary around constant states. Invoking a new weighted energy functional, we establish the uniform estimates with respect to the Mach number, especially for the spatial derivatives of high order. Due to the vorticity-slip boundary condition of the velocity, we decompose the uniform estimates into the part for the fast variables and the other one for the slow variables. In particular, the weighted estimates of highest-order spatial derivatives of the fast variables are crucial for the uniform bounds. Finally, the low Mach number limit is justified by the strong convergence of the density and the temperature, the divergence-free component of the velocity, and the weak convergence of other variables. The methods in this paper can be applied to singular limits of general hydrodynamic equations of hyperbolic-parabolic type, including the full Navier-Stokes equations

Understanding Key Drivers of Mooc Satisfaction and Continuance Intention To Use

Massive Open Online Courses (MOOCs) have attracted global audiences who desire to learn. However, the completion rate of these courses is less than 10 percent. Few studies have systematically researched the influence of expectation-confirmation theory (ECT) and user experience (e.g., flow experience, perceived interest) on user satisfaction of and the continuance intention to use MOOCs. The present study examines the drivers of MOOC satisfaction based on ECT and the influence of satisfaction on user behavior. A research model reflecting the relationships among confirmation, usefulness, interest, flow, satisfaction, and continuance intention to use, and intention to recommend was developed and tested using data collected from 300 subjects. Our findings show that flow and interest are important variables that enhance MOOC satisfaction based on ECT

Social Media In-Feed Advertising: the Impacts of Consistency And Sociability On Ad Avoidance

This study examines the success of in-feed advertisements on social media. As social media is growing in popularity, advertisers have increased their spending on these media. Out of various forms of advertising in-feed advertising has been especially successful in generating click-through rates and comments as compared to other forms of advertising, such as banner ads, pop-up ads. This study attempts to focus on two types of in-feed ad features, namely, consistency and sociability and to evaluate their effects on consumers’ perceptions of goal impediment, ad clutter and ad avoidance. We find that consistency helps to minimize both perceived goal impediment and perceived ad clutter. However, this influence is insignificant among telic users. Perceived sociability is found to mitigate users’ perceptions of in-feed ads as interruptions(ad clutter and goal impediment) as well as avoidance of these ads. Implication for research and theory are presented

Why Viewers Contribute in Live Feed Broadcast

Live feed broadcast, as a new media, enables viewers to interact with broadcasters or other viewers during live video and co-create video with others. Facilitated by synchrony and mobility, the live feed broadcast is now available to anyone having a smart phone consequently leading to increased competition among broadcaster for viewers. The presence of viewers in one’s live feed brings reputation as well as financial benefits to the broadcasters. Hence, the ease of broadcasting would increase competition and hence difficulty in viewer retention. Therefore, this study aims to investigate viewers’ intention to actively participate in a live feed broadcast using a combination of socio-technical perspective and commitment-trust theory. The results reveal that social and technical features influence affective commitment and identification trust, which in turn affects the viewer co-creation behavior. The results will be useful for live feed broadcasters as well as platform providers. Theoretical and managerial implications are discussed

The Impact and Evolution of Individual’s Learning: An Empirical Study in Open Innovation Community

Learning is critical for individuals to increase their performance. However, this benefit of learning is not always realized. Previous studies have distinguished different classifications of learning approaches and reached inconsistent results. Therefore, this study further refines the classification of learning approaches in an open innovation community and explore the individual’s learning curve from a dynamic perspective. Specifically, we focus on whether and under what conditions learning can increase individual’s performance, and how individual\u27s learning curve changes over the tenure. To examine our hypotheses, we collect a dataset includes 48,820 game mods developed by 6,141 creators spanning 7-years from an open game innovation community. The results not only show the significant curve relationship between the four learning approaches and performance, but also demonstrate individual’s learning curve evolves over the tenure. This paper provides valuable suggestions and implications for individuals to choose appropriate learning approaches and obtain better performance under different tenures

Does adoption mean the same to every user? A study of active and passive usage of mobile instant messaging applications

This research-in-progress paper studies the active and passive usage of mobile instant messaging (MIM) applications. Grounded on two-factor theory and three-factor theory, we propose the features of MIM applications influence the active/passive usage of MIM applications through users’ satisfaction and dissatisfaction. The proposed features are categorized into three factors: exciting factors which contain design aesthetics, customization and enjoyment, performance factors which include sociability, convenience and privacy assurance, and basic factors which are application costs and technical functionality. To test hypothetical relationships in this study, we plan to use a survey method. The potential implications to both literature and practice are discussed

PRE-PURCHASE AND POST-PURCHASE SALES PROMOTIONS ON E-COMMERCE PLATFORMS: THE EFFECTS OF PROMOTIONAL BENEFITS ON CUSTOMER-BASED BRAND EQUITY

This research examines the impacts of electronic commerce platforms\u27 sales promotions\u27 benefits on customer-based brand equity (platform brand awareness and platform brand association) and how these relationships are moderated by the promotion stage. Based on the two functions of sales promotions (stimulation vs. maintenance), we propose a five-benefit framework consisting of exploration, convenience, savings, social bonds and structural bonds. Our results reveal the two functions of sales promotions and the positive effects of the benefits on customer-based brand equity (CBBE). The differences between pre- and post-purchase sales promotions are also significant. We discuss the managerial and theoretical implications of these results at the end

Get Tired of Socializing as Social Animal? An Empirical Explanation on Discontinuous Usage Behavior in Social Network Services

This research aims to explain users’ discontinuous usage behavior in social network context. With system features increasing, information flooding and personal network expanding of SNSs, users begin to emerge social network fatigue, and ultimately induce discontinuous usage intention. To explain this phenomenon, we develop a research model based on a cognition-affection-conation framework. This study examines the role of perceived overload (in terms of system feature overload, information overload and social overload) in influencing users’ negative affections of SNSs including social network fatigue and dissatisfaction, and the effects of such emotions on users’ discontinuous intention, which are validated through an empirical survey. The findings of this study contribute to a better understanding of the relationship among perceived overload, social network fatigue and users’ discontinuous usage behavior, and give some implications to SNSs providers to improve this situation

THE EFFECTS OF SOCIAL CAPITAL ON FIRM SUBSTANTIAL AND SYMBOLIC PERFORMANCE IN THE CONTEXT OF E-BUSINESS

Social capital is increasingly regarded as a crucial predictor of performance improvement. However, the Internet is challenging the previous understanding of social capital. In this study, we conduct a research to empirically test the social capital theory in the context of e-business. Specifically, we investigate the influence of social capital on firm substantial and symbolic performance, and compare the influence of social capital on substantial performance to on symbolic performance in the context of e-business. Data were obtained from a survey administered to 205 firms in China. The results suggest that structural and relational capital could influence substantial and symbolic performance significantly. However, we find that cognitive capital could not impact substantive performance significantly, but can influence symbolic performance significantly. We conclude with implications and suggestions for future research

Bioelectrochemical production of hydrogen in an innovative pressure-retarded osmosis/microbial electrolysis cell system: experiments and modeling

Background While microbial electrolysis cells (MECs) can simultaneously produce bioelectrochemical hydrogen and treat wastewater, they consume considerable energy to overcome the unfavorable thermodynamics, which is not sustainable and economically feasible in practical applications. This study presents a proof-of-concept system in which hydrogen can be produced in an MEC powered by theoretically predicated energy from pressure-retarded osmosis (PRO). The system consists of a PRO unit that extracts high-quality water and generates electricity from water osmosis, and an MEC for organic removal and hydrogen production. The feasibility of the system was demonstrated using simulated PRO performance (in terms of energy production and effluent quality) and experimental MEC results (e.g., hydrogen production and organic removal). Results The PRO and MEC models were proven to be valid. The model predicted that the PRO unit could produce 485 mL of clean water and 579 J of energy with 600 mL of draw solution (0.8 M of NaCl). The amount of the predicated energy was applied to the MEC by a power supply, which drove the MEC to remove 93.7 % of the organic compounds and produce 32.8 mL of H2 experimentally. Increasing the PRO influent volume and draw concentration could produce more energy for the MEC operation, and correspondingly increase the MEC hydraulic retention time (HRT) and total hydrogen production. The models predicted that at an external voltage of 0.9 V, the MEC energy consumption reached the maximum PRO energy production. With a higher external voltage, the MEC energy consumption would exceed the PRO energy production, leading to negative effects on both organic removal and hydrogen production. Conclusions The PRO-MEC system holds great promise in addressing water-energy nexus through organic removal, hydrogen production, and water recovery: (1) the PRO unit can reduce the volume of wastewater and extract clean water; (2) the PRO effluents can be further treated by the MEC; and (3) the osmotic energy harvested from the PRO unit can be applied to the MEC for sustainable bioelectrochemical hydrogen production.NPRP grant # 6-289-2-125 from the Qatar National Research Fund (a member of Qatar Foundation)