Initial data to vacuum Einstein equations with asymptotic expansion

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1998.Includes bibliographical references (leaf 92).by Sang Hoon Chin.Ph.D

Detection of Early-Stage Enterprise Infection by Mining Large-Scale Log Data

Recent years have seen the rise of more sophisticated attacks including advanced persistent threats (APTs) which pose severe risks to organizations and governments by targeting confidential proprietary information. Additionally, new malware strains are appearing at a higher rate than ever before. Since many of these malware are designed to evade existing security products, traditional defenses deployed by most enterprises today, e.g., anti-virus, firewalls, intrusion detection systems, often fail at detecting infections at an early stage. We address the problem of detecting early-stage infection in an enterprise setting by proposing a new framework based on belief propagation inspired from graph theory. Belief propagation can be used either with "seeds" of compromised hosts or malicious domains (provided by the enterprise security operation center -- SOC) or without any seeds. In the latter case we develop a detector of C&C communication particularly tailored to enterprises which can detect a stealthy compromise of only a single host communicating with the C&C server. We demonstrate that our techniques perform well on detecting enterprise infections. We achieve high accuracy with low false detection and false negative rates on two months of anonymized DNS logs released by Los Alamos National Lab (LANL), which include APT infection attacks simulated by LANL domain experts. We also apply our algorithms to 38TB of real-world web proxy logs collected at the border of a large enterprise. Through careful manual investigation in collaboration with the enterprise SOC, we show that our techniques identified hundreds of malicious domains overlooked by state-of-the-art security products

Leveraging Douyin for Enhanced Learning Motivation: A Study on Educational Strategies and Student Attitudes

This study investigates the integration of Douyin, known globally as TikTok, in educational settings to enhance student learning motivation. The research aims to understand how the use of Douyin, a platform predominantly used for entertainment, can be effectively repurposed for educational purposes. The study is structured around several key areas: student engagement, self-regulation, teacher facilitation, peer collaboration, personalized learning, and student attitudes towards using Douyin in an educational context. A mixed-method approach is employed, involving both quantitative and qualitative data collection through surveys, interviews, and observational studies. The quantitative data assesses the impact of Douyin on various learning motivation factors, while qualitative data provides in-depth insights into student and teacher experiences. The findings suggest that when used strategically, Douyin can significantly enhance student engagement, promote active learning, and foster a positive learning environment. The study also highlights the importance of teachers’ roles in facilitating effective use of Douyin and the influence of student attitudes on learning outcomes.This research contributes to the growing body of knowledge on digital technology in education, offering practical implications for educators seeking to integrate social media platforms like Douyin into their teaching practices

E-commerce Live Streaming and Chinese Youth's Purchase Intention: Examining the Influential Factors - A Quantitative Analysis

E-commerce live streaming is becoming a popular trend among young consumers in China to make purchases. The purpose of this study is to investigate the factors that influence Chinese youths' purchase intentions through e-commerce live streaming. A structured questionnaire is administered to 446 Chinese youth aged 18 to 35 in Xi'an using quantitative methods and simple random sampling. The survey includes demographic data, e-commerce livestreaming usage, and purchase intentions. The study examines independent variables including visibility, interactivity, emotional appeal, influencer endorsement, information presentation, subjective norm, and perceived behavioral control. Attitude is considered as a mediating variable, while purchase intention serves as a dependent variable. Descriptive statistics and regression analysis are used for data analysis to identify the factors that influence purchase intention. This study aims to contribute to a deeper understanding of the characteristics of e-commerce live streaming and its influence on Chinese youths' purchase intentions. The study found that social norm, attitude and perceived behavior control have significance positive effects on purchase intention. The findings provide valuable insights for e-commerce companies and live streaming platform providers to effectively target and understand this audience. In addition, the study's findings can help marketers and advertisers formulate strategies to reach and influence Chinese youth through e-commerce live streaming

Technical importance ratings in fuzzy QFD by integrating fuzzy normalization and fuzzy weighted average

AbstractFuzzy quality function deployment (QFD) has been extensively used for translating customer requirements (CRs) into product design requirements (DRs) in fuzzy environments. Existing approaches, however, for rating technical importance of DRs in fuzzy environments are found problematic, either incorrect or inappropriate. This paper investigates how the technical importance of DRs can be correctly rated in fuzzy environments. A pair of nonlinear programming models and two equivalent pairs of linear programming models are developed, respectively, to rate the technical importance of DRs. The developed models are examined and illustrated with two numerical examples

Enhancing Learning Engagement and Academic Performance: A Systematic Review among Private College and University Students in Xi'an, China

This systematic review aims to explore the factors influencing learning engagement and its impact on learning performance among private college and university students in Xi'an, China. Learning engagement is a crucial element in students' educational experiences, and understanding the factors that contribute to it can significantly enhance learning outcomes. By systematically reviewing and synthesizing existing literature, this study identifies the key factors influencing learning engagement and investigates the relationship between learning engagement and learning performance. The findings of this review can inform educational institutions and policymakers in designing effective strategies to enhance student engagement and improve academic performance

Assessing the Reliability and Validity of Research Instruments for Measuring Youth Purchase Intention in Xi'an, China: A Pilot Testing

The purpose of this pilot study is to evaluate the reliability and validity of research instruments developed to measure the purchase intention of youth in Xi'an, China. Given the importance of understanding youth purchase intentions and behavior for businesses and marketers, it is critical to have validated research tools, which is not currently the case. The purpose of this study is to develop and evaluate the reliability and validity of such research tools using a sample of young consumers in Xi'an. Overall, the combination of Cronbach's alpha, Pearson's correlation coefficient, construct validity, and Fleiss' Cohen's kappa coefficient are used to thoroughly test the reliability and validity of the research instruments in this study. The research design for this study is quantitative and uses a structured questionnaire administered to a sample of 50 young consumers aged 18 to 35 in Xi'an to investigate the factors that influence their purchase intentions in live streaming e-commerce. The results show that the research instruments are reliable and validated for the main data collection. The results of this study will contribute to the existing knowledge of young people's purchase intentions in China and provide valuable insights for companies and marketers