On hole approximation algorithms in wireless sensor networks

Routing holes in sensor network are regions without operating nodes. They may occur due to several reasons, including cases caused by natural obstacles or disaster suffering areas. Determining the location and shape of holes can help monitor these disaster events (such as volcano, tsunami, etc.) or make smart, early routing decisions for circumventing a hole. However, given the energy limit of sensor nets, the determination and dissemination of the information about the exact shape of a large hole could be unreasonable. Therefore, there are some techniques to approximate a hole by a simpler shape. In this paper, the authors analyze and compare two existing approximation approaches that are considered as the most suitable for the sensor network, namely the grid-based and the convex-hull-based approaches. And a new algorithm of the grid-based approach is also introduced. The performances of all the mentioned algorithms are under analysis and evaluation in both theoretical and experimental perspectives. The findings show that grid-based approach has advantages in saving network energy and providing a finer image of the hole while the convex hull approach is better for making a shorter hole-bypassing the route but not much

THE CONSUMER TRENDS OF SECONDHAND CLOTHING IN YOUNG PEOPLE – THE CASE OF THE GENERATION Z OF VIETNAM

In recent years, secondhand clothes have become a fashion trend that is enthusiastically supported by Vietnamese youth thanks to their fashionability and environmental friendliness. A series of second-hand shops, warehouses, and consignment events have sprung up in parallel with second-hand markets that have existed for many years, still attracting many visitors. In order to examine the trend of secondhand clothing consumption among young Vietnamese, the research team conducted this study. Through the results of the study, it can be seen that the main personal factors leading to the use of secondhand clothes by the survey subjects are spending savings and personal preferences. Most of the decisions to buy secondhand clothes are influenced by the uniqueness of the product and by friends and relatives. The most enabling aspect when using secondhand clothes is the product quality and the product's design, while the aspects that are the most concerns by both users and non-users of secondhand clothes are a matter of hygiene and health

The impacts of socio-economic activities on the environment of Huong river basin

The article analyzes, assesses and forecasts initially the impacts of development process of population, industry, aquaculture and tourism on the environment of Huong river basin. The results shows that the increasing of waste water discharge and waste matter from the population is one of the factors which pollute the environment of Huong river basin, especially in urban areas. Besides, activities of home craft at rural areas, the extension of the scale of industrial zones are forcasted that they will increase the solid waste matter discharge, including noxious solid waste matter. The development of raising prawn by industrial methods at Tam Giang – Cau Hai eliminates millions of square meter of waste water per crop, that pollutes surface water and coastal sea water. Besides, toursim activities at the tours along Huong river basin is one of the factors which pollute this river.В статье даны анализ, оценка и прогноз влияния населения, а также промышленности, аквакультуры и туризма на окружающую среду в бассейне реки Хыонг. Результаты исследования показывают, что одним из основных факторов загрязнения окружающей среды в бассейне реки Хыонг, особенно в пределах городов, является возрастающий сброс сточных вод и других загрязняющих веществ в реки. Вследствие деятельности домашних хозяйств в сельской местности и расширения промышленных зон прогнозируется увеличение количества твердых бытовых отходов, в том числе токсических. Развитие промышленного выращивания креветок в районе Там Гианг – Кау Хай приводит к образованию значительных объемов отработанных вод, которые загрязняют поверхностные воды и прибрежные воды моря. Туристическая деятельность также является одним из факторов загрязнения реки

DESIGN OF A HIGH-SENSITIVITY DEVICE FOR DETECTING WEAK MAGNETIC FIELDS

An anti-serial fluxgate sensor configuration is proposed in this report. The design comprises two identical bilayer-rod fluxgate sensors connected anti-serially in a straight line. Each bilayer-rod sensor is constructed of an excitation coil and a pick-up coil wrapped around a core. The core material consists of Metglas ribbon, an amorphous alloy with high permeability, negligible hysteresis, and a high saturated magnetic field. The core is cut into a bar shape and uses double layers to enhance modulated flux density. A high sensitivity of 10 mV/Oe (with excitation of 45 kHz and 250 mA) is obtained experimentally with low noise of 1´10-5 Oe/Ö Hz at 1 Hz. In measurements of weak magnetic fields, the azimuth response indicates its vector feature. The proposed design is suitable for electronic compass and displacement applications

Changes in physiological and biochemical parameters during the growth and development of guava fruit (Psidium guajava) grown in Vietnam

This research examined the ripening time of guava fruit to provide a scientific basis for better harvesting and preservation of these fruits. Biochemical research methods were used to analyse changes in physiological and biochemical parameters according to the growth and development of guava fruit. The fruit took 14 weeks after anthesis to reach its maximum size in terms of length and diameter. The chlorophyll content in guava peel peaked after 10 weeks, decreasing until week 15. The content of carotenoids, which was low at fruit formation, rose rapidly until fruit ripening, while the vitamin C and reducing sugar contents increased continuously and peaked at week 14. A gradual increase was seen in the starch and total organic acid contents from the beginning of fruit formation, with peaks at 10 weeks, followed by a moderate downward trend. The pectin content showed the same trend, as it declined gradually after peaking at 12 weeks. The first 4 weeks showed an increase in the tannin content, which decreased afterward. The study results show that guava fruit should be harvested after physiological maturity and before ripening completely (14 weeks) to ensure that the nutritional value of the fruit is maintained during storage. Highlights• Xa Li guava at 14 week after anthesis to reach its maximum size in terms of length and diameter. • The chlorophyll content in guava peel peaked after 10 weeks, decreasing until week 15. The content of carotenoids, which was low at fruit formation, rose rapidly until fruit ripening.• The vitamin C and reducing sugar contents peaked at week 14. A gradual increase was seen in the starch and total organic acid contents and peaks at 10 weeks, followed by a moderate downward trend. • The pectin content showed the same trend, as it declined gradually after peaking at 12 weeks. The first 4 weeks showed an increase in the tannin content, which decreased afterward.This research examined the ripening time of guava fruit to provide a scientific basis for better harvesting and preservation of these fruits. Biochemical research methods were used to analyse changes in physiological and biochemical parameters according to the growth and development of guava fruit. The fruit took 14 weeks after anthesis to reach its maximum size in terms of length and diameter. The chlorophyll content in guava peel peaked after 10 weeks, decreasing until week 15. The content of carotenoids, which was low at fruit formation, rose rapidly until fruit ripening, while the vitamin C and reducing sugar contents increased continuously and peaked at week 14. A gradual increase was seen in the starch and total organic acid contents from the beginning of fruit formation, with peaks at 10 weeks, followed by a moderate downward trend. The pectin content showed the same trend, as it declined gradually after peaking at 12 weeks. The first 4 weeks showed an increase in the tannin content, which decreased afterward. The study results show that guava fruit should be harvested after physiological maturity and before ripening completely (14 weeks) to ensure that the nutritional value of the fruit is maintained during storage. Highlights• Xa Li guava at 14 week after anthesis to reach its maximum size in terms of length and diameter. • The chlorophyll content in guava peel peaked after 10 weeks, decreasing until week 15. The content of carotenoids, which was low at fruit formation, rose rapidly until fruit ripening.• The vitamin C and reducing sugar contents peaked at week 14. A gradual increase was seen in the starch and total organic acid contents and peaks at 10 weeks, followed by a moderate downward trend. • The pectin content showed the same trend, as it declined gradually after peaking at 12 weeks. The first 4 weeks showed an increase in the tannin content, which decreased afterward

Current medical product development for diagnosis, surgical planning and treatment in the areas of Neurosurgery, Orthopeadic and Dental-Cranio-Maxillofacial surgery in Vietnam

With the population of 86 million and good GDP growth in recent decades, the medical market in Vietnam is growing fast. However, most of the medical technology products are imported, and the number of locally manufactured ones is limited and they do not have the high competition capability in term of quality, quantity and types. In this paper, the current product development in Vietnam for diagnosis, surgical planning and treatment in the areas of Rehabilitation, Neurosurgery, Orthopeadic and Dental-Cranio-Maxillofacial surgery is presented. A roadmap for medical technology development in Vietnam is propose

REQUIREMENTS IN THE PROCESS OF BUILDING A CONTINGENT OF ETHNIC MINORITY CADRES IN THE MOUNTAINOUS AREAS OF NGHE AN PROVINCE, VIETNAM

Nghe An is a province in Vietnam, with 10 mountainous districts and 1 mountainous town, accounting for 83.31% of the province's natural area. The mountainous area of Nghe An is a place with complicated and dangerous terrain and poor infrastructure; the lowest human development index (HDI) in the province; economic situation is extremely difficult, but it is a place with an important strategic position in terms of socio-economic development and protection of national border security. Therefore, building a contingent of ethnic minority cadres has a very important position and role in the development of the mountainous area of Nghe An. However, the work of building a contingent of ethnic minority cadres in mountainous districts of Nghe An currently has many shortcomings and limitations that need to be overcome, and possible solutions are needed so that the construction building a contingent of ethnic minority cadres in mountainous areas to achieve good results in the coming time.  Article visualizations

CONNECTING MATHEMATICS AND PRACTICE: A CASE STUDY OF TEACHING EXPONENTIAL FUNCTIONS

There is a need for teaching exponential functions to show the necessity for a better match between the knowledge of exponential functions in high schools with the practical application of it in fields. In this research, a teaching process was built in association with teaching situations to show students the relationship between mathematics and real life. The research sample included 76 students in high schools in Vietnam. Additionally, two problems of compound interest and population growth were integrated and were the main research instruments. Data were collected, including student work, and they were analyzed qualitatively. The results showed that students had improved their problem-solving skills and saw the relationship between mathematics and practice. Furthermore, there were some recommendations suggested for textbook authors and teachers. Article visualizations