An inventory of Lattice Boltzmann models of multiphase flows

This document reports investigations of models of multiphase flows using Lattice Boltzmann methods. The emphasis is on deriving by Chapman-Enskog techniques the corresponding macroscopic equations. The singular interface (Young-Laplace-Gauss) model is described briefly, with a discussion of its limitations. The diffuse interface theory is discussed in more detail, and shown to lead to the singular interface model in the proper asymptotic limit. The Lattice Boltzmann method is presented in its simplest form appropriate for an ideal gas. Four different Lattice Boltzmann models for non-ideal (multi-phase) isothermal flows are then presented in detail, and the resulting macroscopic equations derived. Partly in contradiction with the published literature, it is found that only one of the models gives physically fully acceptable equations. The form of the equation of state for a multiphase system in the density interval above the coexistance line determines surface tension and interface thickness in the diffuse interface theory. The use of this relation for optimizing a numerical model is discussed. The extension of Lattice Boltzmann methods to the non-isothermal situation is discussed summarily.Comment: 59 pages, 5 figure

A Forensically Sound Adversary Model for Mobile Devices

In this paper, we propose an adversary model to facilitate forensic investigations of mobile devices (e.g. Android, iOS and Windows smartphones) that can be readily adapted to the latest mobile device technologies. This is essential given the ongoing and rapidly changing nature of mobile device technologies. An integral principle and significant constraint upon forensic practitioners is that of forensic soundness. Our adversary model specifically considers and integrates the constraints of forensic soundness on the adversary, in our case, a forensic practitioner. One construction of the adversary model is an evidence collection and analysis methodology for Android devices. Using the methodology with six popular cloud apps, we were successful in extracting various information of forensic interest in both the external and internal storage of the mobile device

Effects of international gold market on stock exchange volatility: evidence from asean emerging stock markets

This paper examines behaviors of returns and volatility of ASEAN emerging stock markets (Indonesia, Malaysia, Philippines, Thailand and Vietnam), incorporating with the effects from the international gold market. The estimates of GARCH(1,1) and GJR(1,1) for these stock markets indicate that the GJR(1,1) model is preferred to GARCH(1,1), except Vietnam. However, under the exogenous effects from international gold market such as the 1 day lagged returns and the 1 day lagged volatility of gold, the GARCH(1,1)-X model captures better stock market volatility behavior than GJR(1,1)-X, except Indonesia. Interestingly, gold could be a substitute commodity for stocks in Vietnam and the Philippines, while it could be a complement for stocks in Indonesia, Thailand and Malaysia.Volatility, GARCH-X, Gold effects, ASEAN emerging stock markets

ENTREPREURIAL SELF-EFFICACY AND THE LIKELIHOOD OF BEING SELF-EMPLOYED – A COMPARISON OF URBAN AND RURAL AREAS IN VIETNAM

A large body of entrepreneurship research has focused on the relationship between entrepreneurial self-efficacy and start-up activity. Yet, little is known about how the interplay of these mechanisms is moderated by informal institutional conditions (e.g., social traits in rural and urban regions). Particularly, Vietnam, a country with a socialist-oriented market economy, has emerged as one of the world’s most entrepreneurial countries. This study examines how the effects of individuals’ entrepreneurial self-efficacy on being self-employed are contingent on institutional environments (e.g., rural and urban areas). Statistical analyses of 2013 to 2015 data from the Global Entrepreneurship Monitor (GEM) project for Vietnam provide empirical evidences that entrepreneurial self-efficacy is significantly and positively associated with being self-employed, and that this effect is more pronounced for individuals in rural than those in urban areas. Moreover, the findings show that people in rural Vietnam are more willing to be self-employed than their peers in urban areas. This difference is explained by the distinct impact of the informal institutional variable, entrepreneurial self-efficacy (e.g., the knowledge, skills, and experience required to start a new business) that individuals living in rural areas may gain from entrepreneurship promotion and start-up programs supported by the Vietnamese leadership. Our findings have implications for national entrepreneurship programs and financial support for start-up projects in rural areas

Microgrid Renewable Energy Integration

The Microgrid is a small-scale electrical system that is designed to give Cal Poly students hands-on experience on power generation, system protection, distribution, and automation that would otherwise be very difficult to experiment in a large-scale model. To closely replicate the modern electrical grid, a renewable energy source shall be added to the Microgrid in conjunction with the existing synchronous generators. Electrical engineering student, Virginia Yan initiated this effort, namely Grid-Tied Solar System project [1], by designing and constructing a set of solar panels and microinverter for future connection to the Microgrid. The scope of Virginia’s project was, however, limited to designing and constructing the panels and microinverter. This Microgrid Renewable Energy Integration project aims to integrate the designed solar panels and microinverter to the Microgrid by testing the microinverter when running on islanded mode that replicates the Microgrid and eventually running with the Microgrid. The project develops test methods and solutions to enhance integration capability from the test results. In addition, this project implements basic power protection elements such as over-current and under-voltage. Protection schemes and monitoring are configured using Schweitzer Engineering Laboratories (SEL) relays, such as SEL-751 Feeder Protection Relay and SEL-735 Power Quality Meter. The success of the Microgrid Renewable Energy Integration project guarantees a smooth synchronization and secured operation of the microinverter to the Microgrid

The DKAP Project The Country Report of Vietnam

Viet Nam is at the beginning of the Fourth Industrial Revolution. In order to grasp the opportunities that the revolution has brought about, and to successfully build the society of digital citizens, there must be the demand of enhancing the capacity and capability for students to meet international standards in terms of Information and Communications Technology (ICT) skills. Viet Nam was selected as one of the four countries (Viet Nam, Bangladesh, Fiji, and the Republic of Korea) to join UNESCO Bangkok’s “Digital Kids Asia Pacific (DKAP)” project, a comparative cross-national study with the aim to seek the understanding and address children’s ICT practices, attitudes, behaviors, and competency levels within an educational context. Thanks to the project, the Vietnamese research team completely conducted the survey in twenty (20) schools from five (5) provinces in Viet Nam. With the data on the digital citizenship competency levels of 1,061 10th grade students, the research team discovered the valuable findings to draw an initial big picture for Vietnamese policy makers, educators, and teachers about digital citizenship competencies of 15-year-old Vietnamese students