An overview of 5G technologies

Since the development of 4G cellular networks is considered to have ended in 2011, the attention of the research community is now focused on innovations in wireless communications technology with the introduction of the fifth-generation (5G) technology. One cycle for each generation of cellular development is generally thought to be about 10 years; so the 5G networks are promising to be deployed around 2020. This chapter will provide an overview and major research directions for the 5G that have been or are being deployed, presenting new challenges as well as recent research results related to the 5G technologies. Through this chapter, readers will have a full picture of the technologies being deployed toward the 5G networks and vendors of hardware devices with various prototypes of the 5G wireless communications systems

A study on multi-criteria decision-making in powder mixed electric discharge machining cylindrical shaped parts

In life as well as in engineering, many times, it is necessary to choose the best option among many different options. That will be more difficult when the criteria given for the selection contradict each other. For example, when external cylindrical grinding, the minimum surface roughness requirement necessitates a small depth of cut and feed rate. The material removal rate will be reduced in this case, and this requirement will conflict with the maximum material removal rate requirement. To solve the above problem, a very useful tool is multi-criteria decision-making (MCDM). In this paper, for the first time, MCDM results for powder mixed discharge machining (PMEDM) cylindrical parts of SKD11 tool steel with copper electrodes have been presented. In this work, eighteen experiments with the L18 (16×53) design using the Taguchi method were conducted. Six main input process parameters include the powder concentration, the pulse current, the servo voltage, the pulse on time, and the pulse off time. To select an alternative that simultaneously ensures two criteria including minimum surface roughness (RS) and maximum material removal speed (MRS), four different MCDM methods including MAIRCA (Multi-Attributive Ideal-Real Comparative Analysis), MARCOS (Measurement of Alternatives and Ranking according to Compromise Solution), TOPSIS (Technique for order of preference by similarity to ideal solution), and EAMR (Area-based Method of Ranking) and two methods of criteria weight calculation including MEREC (Method based on the Removal Effects of Criteria) and Entropy methods were selected. The results of MCDM when PMEDM SKD11 tool steel cylindrical parts with two methods for weight determination and four methods for solving MCDM problem were evaluated. In addition, the best alternative to ensure simultaneous minimum RS and maximum MRS was proposed

BACH HO FIELD GEOLOGICAL FEATURES IDENTIFICATION USING WELL LOGGING DATA

Link for citation: Nguyen Xuan Kha, Pham Xuan Son, Hoang Van Quy, Nguyen Tuan, Truong Quoc Thanh, Mai Huu Xuan, Tran Van Xuan.  Bach ho field geological features identification using  well logging data. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 35-42. In Rus. The relevance. Well geophysics is considered as a typical method that can assist in determining the petrophysics properties of reservoirs and further location of the petroleum product-containing reservoirs. For reservoirs formed from fractured basement rock, studies on the petrophysics properties of fracture zones can contribute to the identification of petroleum products. The main aim. The study applied the cross-plotting method based on raw well-logging data to identify the possible correlation between the gamma-ray logging with well-logging including neutron porosity, sonic transient time, and bulk density in three wells (BH-433, BH-809, and BH-905) of Bach Ho field in the Cuu Long Basin, Vietnam. Methods. To deploy this study, well-logging data were integrated into formation of micro images and neutro, speed of sound, and density of the basement at the surveyed reservoir positions. Results. The results indicated that granite in the investigated zones responds to the two tight value ranges (no-oil exist zones) neutro (0,000–0,100) and speed of sound (46–64), and neutro (0,000–0,100) and density (2,375–2,750) while the value ranges deviate from 0,000–0,100, 46–64, and 2,375–2,750, respectively for neutro, speed of sound, and density are closely related to the good permeability and porosity zones (oil exist zones). Based on the findings, it can be confirmed that the cross-plotting analysis has contributed positively to the initial assessment of potential ranges of the oil reservoirs in Bach Ho field. The application of the cross-plotting method will contribute to enhancing the predictability of oil and gas in the reservoirs

A comprehensive study on the efficacy of a wearable sleep aid device featuring closed-loop real-time acoustic stimulation

Difficulty falling asleep is one of the typical insomnia symptoms. However, intervention therapies available nowadays, ranging from pharmaceutical to hi-tech tailored solutions, remain ineffective due to their lack of precise real-time sleep tracking, in-time feedback on the therapies, and an ability to keep people asleep during the night. This paper aims to enhance the efficacy of such an intervention by proposing a novel sleep aid system that can sense multiple physiological signals continuously and simultaneously control auditory stimulation to evoke appropriate brain responses for fast sleep promotion. The system, a lightweight, comfortable, and user-friendly headband, employs a comprehensive set of algorithms and dedicated own-designed audio stimuli. Compared to the gold-standard device in 883 sleep studies on 377 subjects, the proposed system achieves (1) a strong correlation (0.89 ± 0.03) between the physiological signals acquired by ours and those from the gold-standard PSG, (2) an 87.8% agreement on automatic sleep scoring with the consensus scored by sleep technicians, and (3) a successful non-pharmacological real-time stimulation to shorten the duration of sleep falling by 24.1 min. Conclusively, our solution exceeds existing ones in promoting fast falling asleep, tracking sleep state accurately, and achieving high social acceptance through a reliable large-scale evaluation

The association between high ambient temperature and risk of hospitalization: a time-series study in eight ecological regions in Vietnam

Viet Nam is among the countries most threatened by and vulnerable to climate change and extreme weather events. However, research on the temperature-morbidity relationship at the national scale has been scarce. This study aimed to assess the impact of high temperatures on the risk of hospital admissions for all causes and heat-sensitive diseases across eight ecological regions in Vietnam. The study utilized a longitudinal dataset that included hospitalization and meteorological data from eight provinces representing eight regions in Vietnam. A time series analysis was applied using the generalized linear and distributed lag models with a quasi-Poisson family to examine the temperature-hospitalization association in each province. A random-effects meta-analysis was used to calculate the pooled estimate of risk for the national scale. The country-level pooled effects (%, [95% CI]) indicated that a 1 °C increase above the threshold temperature (19 °C) increased the hospitalization risk for all causes and infectious diseases by 0.8% [0.4%–1.2%] and 2.4% [1.02%–1.03%], respectively at lag 0–3 d. The effects of heat on respiratory diseases and mental health disorders were not significant. At the regional level, the association varied across eight regions, of which the Northern parts tended to have a higher risk than the Southern. This is among very few national-scale studies assessing hospitalization risk associated with high temperatures across eight ecological regions of Vietnam. These findings would be useful for developing evidence-based heat-health action plans

Застосування методів topsis, mairca та EAMR для багатокритеріального прийняття рішень при шліфуванні кругами з кубічного нітриду бору

Determining the best cutting mode is a common problem for machining processes as well as for CBN (Cubic Boron Nitride) grinding on Computer Numerical Control (CNC) machines. It is even more important when it is necessary to choose a solution that meets many goals, which are in conflict. This paper presents the results of a multi-criteria decision-making (MCDM) study on CBN grinding of cylindrical-shaped parts on CNC milling machines. Three MCDM methods,  including TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution), MAIRCA (Multi-Attributive Ideal-Real Comparative Analysis), and EAMR (Evaluation by an Area-based Method of Ranking) were applied in this work. Besides, MEREC (Method based on the Removal Effects of Criteria) and Entropy methods were used to determine the weights of the criteria. In addition, the Taguchi method with L18 orthogonal array (6^1+3^3) design was used for the design of an experiment, which has four input factors including the depth of dressing cut, the spindle speed, the feed rate, and the wheel diameter. Two criteria, including the surface roughness (SR) and the material removal speed (MRS) were selected as the response outputs. The reason for choosing these two criteria is because SR and MRS are two very important output factors of a mechanical machining process as well as of the CBN grinding process on a CNC milling machine. In particular, these two criteria are always in conflict with each other. Small SR requirements will require small values of the feed speed and the depth of cut. This will lead to the reduction of MRS. From the results of this study, the use of different methods for MCDM was evaluated. In addition, rankings of alternatives have been given according to MCDM methods. Furthermore, the best alternative to guarantee both the minimum SR and the maximum MRS has been foundВизначення найкращого режиму різання є поширеною задачею у процесах механічної обробки, а також шліфування кругами з КНБ (кубічного нітриду бору) на верстатах з числовим програмним управлінням (ЧПУ). Тим більше, коли необхідно вибрати рішення, що відповідає багатьом цілям, які суперечать одна одній. У статті представлені результати дослідження багатокритеріального прийняття рішень (БКПР) щодо шліфування кругами з КНБ деталей циліндричної форми на фрезерних верстатах з ЧПУ. У роботі застосовувалися три методи БКПР, включаючи TOPSIS (метод упорядкованої переваги через подібність до ідеального рішення), MAIRCA (мультиаттрибутний порівняльний аналіз реального та ідеального) і EAMR (оцінка методом зонального ранжування). Крім того, для визначення вагових коефіцієнтів критеріїв використовувалися методи MEREC (метод, заснований на ефектах видалення критеріїв) та Entropy (ентропії). Також для планування експерименту, що має чотири вхідних фактори, включаючи глибину різання, швидкість обертання шпинделя, швидкість подачі та діаметр круга був використаний метод Тагучі з ортогональною матрицею L18 (6^1+3^3). В якості відповідних даних були обрані два критерії, включаючи шорсткість поверхні (ШП) і швидкість знімання матеріалу (ШЗМ). Вибір даних критеріїв обумовлений тим, що ШП та ШЗМ є двома дуже важливими вихідними факторами у процесі механічної обробки, а також шліфування кругами з КНБ на верстаті з ЧПУ. Зокрема, ці два критерії завжди суперечать один одному. Малі вимоги до ШП вимагатимуть невеликих значень швидкості подачі та глибини різання, що призведе до скорочення ШЗМ. За результатами дослідження було оцінено застосування різних методів для БКПР. Крім того, були дані рейтинги альтернативних рішень відповідно до методів БКПР. Також було знайдено найкраще альтернативне рішення, що гарантує як мінімальну ШП, так і максимальну ШЗ

Advanced non-cardia gastric cancer and Helicobacter pylori infection in Vietnam

Abstract Background The incidence of gastric cancer in the Northern city, Hanoi is higher than in the Southern city, Ho Chi Minh, Vietnam. We previously reported that Helicobacter pylori vacA m1 genotype might be responsible for the difference between the two cities, however, the study only included non-cancer patients. The aim of this study is to investigate the non-cardia gastric cancer characteristics and the role of H. pylori virulence on different non-cardia gastric cancer incidence between two cities in Vietnam. Methods and Results We recruited 282 non-cardia gastric cancer patients that had undergone gastroscopy in two cities, Ho Chi Minh and Hanoi, Vietnam. Characteristics of non-cardia gastric cancer were late age of onset (mean age, 62.5 years), predominance in males (ratio of males/females; 3.9:1), diffuse type (55.3%), and high prevalence of H. pylori infection (79.4%). H. pylori infection and the vacA m1 genotype conferred an increased risk for GC (OR, 2.02; 95% CI 1.4–3.0; P = 0.0003 and OR, 2.7; 95% CI 1.5–4.7; P = 0.001, respectively). Interestingly, the presence of vacA m1 genotype in the gastric cancer group was significantly higher than that in the non-cancer group (68.8% vs 44.9%, P = 0.001) and the significant tendency still observed in Ho Chi Minh (67.6% vs 31.9%, P < 0.0001). Conclusion We first describe the characteristics of non-cardia gastric cancer in Vietnam. Helicobacter pylori infection was associated with the development of non-cardia GC. vacA m1 genotype might contribute to incidence differences between the two cities

Flavones from Combretum quadrangulare Growing in Vietnam and Their Alpha-Glucosidase Inhibitory Activity

Combretum quadrangulare Kurz is widely used in folk medicine in Eastern Asia and is associated with various ethnopharmacological properties including hepatoprotective, antipyretic, analgesic, antidysenteric, and anthelmintic activities. Previous phytochemical investigations reported the presence of numerous triterpenes (mostly cycloartanes, ursanes, lupanes, and oleananes) along with dozens of flavonoids. However, the extracts of C. quadrangulare and isolated flavonoids have not been evaluated for their alpha-glucosidase inhibition. In the frame of our efforts dedicated to the chemical investigation of Vietnamese medicinal plants and their biological activities, a phytochemical study of the MeOH extract of the leaves of C. quadrangulare using bioactive guided isolation was undertaken. In this paper, the isolation and structure elucidation of twelve known compounds, 5-hydroxy-3,7,4′-trimethoxyflavone (1), ayanin (2), kumatakenin (3), rhamnocitrin (4), ombuin (5), myricetin-3,7,3′,5′-tetramethyl ether (6), gardenin D (7), luteolin (12), apigenin (13), mearnsetin (14), isoorientin (15), and vitexin (16) were reported. Bromination was applied to compounds 2 and 3 to provide four new synthetic analogues 8–11. All isolated and synthesized compounds were evaluated for alpha-glucosidase inhibition and antibacterial activity. Compounds 4 and 5 showed moderate antibacterial activity against methicillin-resistant Staphylococcus aureus while others were inactive. All compounds failed to reveal any activity toward extended spectrum beta-lactamase-producing Escherichia coli. Compounds 2, 4, 6–9, and 11–14 showed good alpha-glucosidase inhibition with IC50 values in the range of 30.5–282.0 µM. The kinetic of enzyme inhibition showed that 8 and 11 were noncompetitive type inhibition against alpha-glucosidase. In silico molecular docking model indicated that compounds 8 and 11 were potential inhibitors against enzyme α-glucosidase

Molecular Epidemiology of Helicobacter pylori Infection in a Minor Ethnic Group of Vietnam: A Multiethnic, Population-Based Study

The Helicobacter pylori-induced burden of gastric cancer varies based on geographical regions and ethnic grouping. Vietnam is a multiethnic country with the highest incidence of gastric cancer in Southeast Asia, but previous studies focused only on the Kinh ethnic group. A population-based cross-sectional study was conducted using 494 volunteers (18–78 years old), from 13 ethnic groups in Daklak and Lao Cai provinces, Vietnam. H. pylori status was determined by multiple tests (rapid urease test, culture, histology, and serology). cagA and vacA genotypes were determined by PCR-based sequencing. The overall H. pylori infection rate was 38.1%. Multivariate analysis showed that variations in geographical region, age, and ethnicity were independent factors associated with the risk of H. pylori acquisition. Therefore, multicenter, multiethnic, population based study is essential to assess the H. pylori prevalence and its burden in the general population. Only the E De ethnicity carried strains with Western-type CagA (82%) and exhibited significantly lower gastric mucosal inflammation compared to other ethnic groups. However, the histological scores of Western-type CagA and East-Asian-type CagA within the E De group showed no significant differences. Thus, in addition to bacterial virulence factors, host factors are likely to be important determinants for gastric mucosal inflammation and contribute to the Asian enigma