Towards an interactive index structuring system for content-based image retrieval in large image databases

Advisors: Muriel Visani, Alain Boucher, Jean-Marc Ogier. Date and location of PhD thesis defense: 2 October 2013, University of La RochelleIn recent years, the expansion of acquisition devices such as digital cameras, the development of storage and transmission techniques and the success of tablet computers facilitate the development of many large image databases as well as the interactions with the users. This thesis [1] deals with the problem of Content-Based Image Retrieval (CBIR) on these huge masses of data. Traditional CBIR systems generally rely on three phases: feature extraction, feature space structuring and retrieval. In this thesis, we are particularly interested in the structuring phase (normally called indexing phase), which plays a very important role in finding information in large databases. This phase aims at organizing the visual feature descriptors of all images into an efficient data structure in order to facilitate, accelerate and improve further retrieval. We assume that the feature extraction phase is completed and the image feature descriptors which are usually low-level features describing the color, shape, texture, etc. of all images are available. Instead of traditional structuring methods, clustering methods which organize image descriptors into groups of similar objects (clusters), without any constraint on the cluster size, are studied. The aim is to obtain an indexed structure more adapted to the retrieval of high dimensional and unbalanced data. Clustering process can be done without prior knowledge (unsupervised clustering) or with a limited amount of prior knowledge (semi-supervised clustering)

Best Strategies for Mitigating Choice Overload

Objectives of the study As the growth in product variety and assortment continues to soar, consumers nowadays are more susceptible to choice overload. In order to attract and retain customers, retailers must take actions to mitigate the choice overload problem in their product assortments. Hence, this study aims to find out best strategies that enterprises can employ to mitigate choice overload. Academic background and methodology Prior research has mainly concentrated on proving the existence of choice overload problem as well as the effects of assortment size reduction on mitigating the problem. However, little research has been done on examining additional mitigation strategies for choice overload. Therefore, this study aims to identify further approaches that enterprises can adopt to mitigate choice overload problem by examining different assortment strategies as well as the consumer groups in experienced choice overload level. The assortment strategies examined in the study are Assortment Size Reduction, Categorization, Provision of a Default Option and Unconscious Information Processing. As for consumer groups, different groups classified by Gender, Age, Education and Continent were compared. The thesis employed a behavioral experiment to examine participants’ degree of experienced choice overload when making their decisions in different assortment conditions. Participants were assigned to 9 different assortment scenarios corresponding to different combinations of mitigation approaches. After making their decision in the assortment, they were asked to evaluate their choice overload based on a set of statements. The experiment results revealed the effectiveness of different mitigation approaches and the differences among consumer groups in experienced choice overload. Findings and conclusion First, the experiment confirmed the existence of choice overload effect. Second, the experiment suggested the effectiveness of assortment strategies. Third, we uncovered that most effective mitigation strategies are Reduction of Assortment Size and Unconscious Information Processing. Fourth, the mitigation strategies were discovered to be more effective when being in combination with each other instead of being stand-alone. Finally, regarding the differences among consumer groups in experienced choice overload, those who demonstrated low levels of choice overload are men, elders and highly educated people. These results suggest various actions that enterprises should consider to mitigate choice overload in their product assortments

Effect of chromium substituted on structural and magnetic characterization lithium ferrite nanoparticles

In this work, we present a structural, morphology and magnetic study of the Li0.5Fe2.5-xCrxO4 spinel nanoparticles (x = 0, 0.5, 0.75, 1, and 1.25) with mean particle size of 20-30 nm prepared by sol-gel method. The lattice constants and the size of particle decrease with increasing Cr concentration. In these samples, the preference of Cr3+ and Li+ ions in the octahedral sites and a small degree of site-interchange between Li+ in the octahedral sites and Fe3+ in the tetrahedral sites were found which increases with increasing the Cr content. A decrease of magnetization due to the spin disorder in the surface layer of the particles was observed. The spontaneous magnetization at 5K suggests the Néel type of magnetic ordering in these samples. The magnetic coercivity is discussed in terms of particle size, morphology and chromium substitution. Keywords. Chromium substitution, sol-gel method, nanoparticles, lithium ferrite

Oportunidades para Colombia en atracción de turismo de Vietnam: esmeraldas, salud y aprendizaje de español

Vietnam and Colombia established diplomatic relations in January 1979, and since then the relationship between these two countries has been strengthened with state visits, managing to increase bilateral cooperation mainly in areas such as tourism, cultural exchange, and exposition. and agricultural import. Both are countries with many similarities; They have suffered a war and now they are on the road to development, they have a great biodiversity and a young population, they are also two leading countries in the export of coffee to the world. Taking into account these similarities and the potential to strengthen bilateral relations, this article analyzes the promotion of tourism as a key axis in the bilateral relationship. In that sense, the attraction of tourism from Vietnam to Colombia is analyzed, evidencing the tourism trend of the Vietnamese and the types of trips that Colombia can offer them.Vietnam y Colombia establecieron relaciones diplomáticas en enero de 1979, y desde ese momento la relación entre estos dos países se ha fortalecido con las visitas de Estado, logrando aumentar la cooperación bilateral principalmente en ejes como el turismo, el intercambio cultural, y la expo tación e importación agrícola. Ambos son países con muchas similitudes; han sufrido una guerra y ahora están en la vía del desarrollo, tienen una gran biodiversidad y una población joven, además son dos países líderes en la exportación de café al mundo. Teniendo en cuenta estas similitudes y el potencial para fortalecer las relaciones bilaterales, este artículo analiza la promoción del turismo como un eje clave en la relación bilateral. En ese sentido, se analiza la atracción del turismo de Vietnam hacia Colombia, evidenciando la tendencia de turismo de los vietnamitas y los tipos de viajes que Colombia puede ofrecerles

Online Learning Management in Covid-19 Pandemic: Case in Vietnam

The world is dealing with the COVID-19 epidemic, which has created enormous impacts on education, especially on learning management, requiring the adjustment and implementation of an online learning system effectively.The process of digital transformation has been promoted rapidly to adapt to new conditions in Education.Nowadays the online system has facilitated students of all levels to study at anytime and anywhere owing to the development of technologies.However, the existence and limits ofonline teaching and learning have been mentioned such as the complicated implementation or limited communication of active teaching methods compared to an actual classroom. Therefore, innovative teaching strategies and models are now required to be more diverse to encourage learners to focus on the lesson.In this study, we proposed an optimal paradigm of online learning management: the combination of several supported programs to effectivelymanage the teaching process. The approach has been appliedtothe Basic Informatics course for students majoring in Primary Education at the Thai Nguyen University of Education, Vietnam, and suggesteda flexible approach to stimulate learners' enthusiasm, express opinions, and actively participate in activities for enhancing their achievements. In addition, the investigation and discussion from lecturers and students about the digital transformation challenges in learning management also were presented and proposed the necessary information for the educational process

TEACHERS’ PERCEPTIONS TOWARD BLENDED TEACHING APPLIED IN EFL CLASSROOM

Blended teaching has recently attracted a lot of attention from educators and researchers worldwide. In Vietnam, blended teaching has been applied at various universities in different forms. However, few studies have been conducted to explore EFL teachers’ perceptions of the use of blended teaching in Vietnam. The current study used a questionnaire to explore the perceptions of thirty EFL teachers from a large university in Vietnam. Findings reveal that EFL teachers gain various benefits and encounter different challenges when applying blended teaching in their classrooms.  Article visualizations

English teachers’ perception and attitudes of scaffolding method in teaching academic writing: An exploratory study at universities in Vietnam

The primary aim of this research is to investigate the impact of utilizing the scaffolding method on teaching academic writing in the context of English as a Foreign Language (EFL) at universities in Vietnam. This mixed-method study examined the attitudes and perceptions of 88 EFL educators from diverse backgrounds and degree levels who were randomly selected for the research. Methodologically, data were gathered and analyzed using the appropriate methods for each instrument, including a questionnaire and focus group discussion (FGD). Theoretically, the study is a medley of relevant theories and approaches such as Vygotsky’s Sociocultural Theory of Learning, the Scaffolding theory, and the ‘High challenge - High support’ pedagogy. The results of this study suggest that participants used scaffolding to some extent and had strongly positive attitudes and perceptions regarding its practical aspects; however, the findings also revealed that the surveyed lecturers are deficient in the necessary knowledge and skills. In addition, the study's findings imply that EFL teachers need training on how to properly use scaffolding as a pedagogical strategy to facilitate teaching academic writing to EFL students