A novel method for determining fixed running time in operating electric train tracking optimal speed profile

Tracking the optimal speed profile in electric train operation has been proposed as a potential solution for reducing energy consumption in electric train operation, at no cost to improve infrastructure of existing Metro lines as well. However, the optimal speed profile needs to meet fixed running time. Therefore, this paper focuses on a new method for determining the fixed running time complied with the scheduled timetable when trains track the optimal speed profile. The novel method to ensure the fixed running time is the numerical-analytical one. Calculating accelerating time ta, coasting time tc, braking time tb via values of holding speed vh, braking speed vb of optimal speed profile with the constraint condition: the running time equal to the demand time. The other hands, vh and vb are determined by solving nonlinear equations with constraint conditions. Additionally, changing running time suit for each operation stage of metro lines or lines starting to conduct schedules by the numerical-analytical method is quite easy. Simulation results obtained for two scenarios with data collected from electrified trains of Cat Linh-Ha Dong metro line, Vietnam show that running time complied with scheduled timetables, energy saving by tracking optimal speed profile for the entire route is up to 8.7%, if the running time is one second longer than original time, energy saving is about 11.96%

Super-capacitor energy storage system to recuperate regenerative braking energy in elevator operation of high buildings

In operating phases of elevators, accelerating, braking modes occur frequently, so braking energy recuperation of elevators has contributed considerably to decrease the total electric energy consumption for operating elevators in multi-floor buildings. In this paper, the supercapacitor energy storage system is used to recover regenerative braking energy of elevators when they operate down full-load and up no-load, reducing fluctuation of voltage on DC bus as well. Therefore, super-capacitor energy storage system (SCESS) will be parallel with line utility to recuperate regenerative braking energy in braking phase and support energy for acceleration phase. The surplus energy will be stored in the supercapacitors thanks to a DC-DC converter capable of exchanging energy bidirectionally in buck/boost modes, and designing control strategy including two control loops. Inner loop-current loop: controlling charge/discharge process of supercapacitors by current iL complying with operation characteristic of elevator; Outer loop-voltage loop: managing UDC-link at a fixed value. Simulation results with elevator system of the ten-floor building, Hanoi, Vietnam installed SCESS have been verified on MATLAB Simulink, SimPowerSystem with saving energy level about 30%

Research and Development of the Pupil Identification and Warning System using AI-IoT

Currently, pupils being left in the classroom, in the house or in the car is happening a lot, causing unintended incidents. The reason is that parents or caregivers of pupils go through busy and tiring working hours, so they accidentally leave pupils in the car, indoors, or forget to pick up students at school. In this paper, we developed an algorithm to recognize students who use neural networks and warn managers, testing on a model integrated Raspberry Pi 4 kit programmed on Python in combination with cameras, sim modules, and actuators to detect and alert abandoned pupils to the manager to take timely remedial measures and avoid unfortunate circumstances. With the ability to manage students, the system collects and processes images and data on student information for artificial intelligence (AI) systems to recognize when operating. The system of executive structures serves to warn when students are left in the car, in the classroom, or in the house to avoid unintended incidents or safety risks

CHANGES IN PLASMA LEVELS OF STEROID HORMONES DURING SEXUAL MATURATION OF MALE HELICOPTER CATFISH (WALLAGO ATTU) IN CAPTIVITY

In order to provide reliable indicators of the spawning season of captive helicopter catfish (Wallago attu), this study evaluated the temporal variation in gonadosomatic index (GSI), plasma levels of testosterone (T), and 11-ketotestosterone (11-KT) in male broodstock in captivity. GSI was estimated as the percentage of the relative weight of testis to total body weight. Plasma levels of sex steroids were determined by enzyme-linked immunosorbent assay (EIA). Testis samples were dehydrated and embedded in paraffin, then sectioned at 5 μm thickness. The highest level of T (402.1 ± 16.7 pg/mL) was found in June, followed by a peak in 11-KT level (76.9 ± 4.7 pg/mL) in May. Testes containing the highest concentrations of spermatozoa were observed from June to August. The GSI of males increased significantly from January to June and peaked in July (2.14%). Taken together, we conclude that the spawning season of captive helicopter catfish occurs from June to August. These results will contribute to the basic knowledge of the reproductive biology of helicopter catfish, which can be useful in artificial breeding

FACTORS RELATED TO THE AWARENESS AND BEHAVIOR OF MARIJUANA USE AMONG UNIVERSITY STUDENTS IN CAPITAL HANOI, VIETNAM

Abstract The increasing use of addictive substances, especially marijuana, among university students has increased the burden of disease and social issues. However, the specific data about the prevalence and factors relating to marijuana use among university students is still limited. This study aims to provide the initial research literature about factors affecting the awareness and behavior of marijuana use among university students in Hanoi. The study employed two primary methods: a survey questionnaire and an in-depth interview with a sample of 324 diverse university students. According to research findings, students are generally uncertain about the effects of marijuana and take a neutral stance on its social acceptability. The overall prevalence of marijuana use among university students in Hanoi is 7.4%, of which the rate of use in males is 9.4% and in females is 4.1%. Marijuana use is also influenced by peers' behavior, and parents' false perception of their children's drug prevention capability and marijuana's accessibility may also play a factor

Financial Performance and Corporate Governance in Microfinance: Evidence from Vietnam

Good corporate governance is considered a building block of success for microfinance institutions (MFIs) as it is presumed to help them in achieving their social and financial goals. This study analyzes the corporate governance and financial performance relationship for MFIs in Vietnam. We construct a corporate governance index based on seven measures pertaining to board size and composition, CEO characteristics, and ownership type. We then estimate the two-way relationship between this index and each of five different financial performance indicators. To address the likely simultaneity between corporate governance and financial performance, we adopt a two-stage least squares estimation approach with instrumental variables. The results confirm the endogenous nature of corporate governance and financial performance. We conclude that profitability and sustainability of MFIs improve with good governance practices and conversely that more profitable and sustainable MFIs have better governance systems. Keywords: Corporate governance, financial performance, microfinance. DOI: 10.7176/EJBM/12-3-12 Publication date: January 31st 2020

Effects of dietary tryptophan on cannibalism, survival and growth of Wallago attu (Bloch & Schneider, 1801) juveniles

This study aims to evaluate the effects of supplemented commercial diets with tryptophan (TRP) on plasma serotonin, cannibalism, survival rate, and growth of Wallago attu (helicopter catfish). After one week of acclimation, 3,200 juveniles of helicopter catfish (BW = 2.5 ± 0.27 g, total length = 5.6 ± 0.43 cm) were randomly assigned for the experiment in fifteen plastic tanks (200 L). The experiment was conducted with five treatments (CT – 0 g TRP/kg – control group, T1 – 5 g TRP/kg, T2 – 10 g TRP/kg, T3 – 20 g TRP/kg, and T4 – 40 g TRP/kg) in a completely randomized design with three replications for four weeks. The results from the enzyme-linked immunosorbent assay reveal that TRP-supplemented diets effectively increased the serotonin level (5-HT) in the plasma of the catfish. The serotonin level increased with the dose of TRP added to the feed. Furthermore, a higher TRP level significantly decreased cannibalism and improved the final survival of the fish. However, the fish’s growth rate among treatments T1, T2, T3, and T4 was not significantly different, but there was a statistical difference between the experimental treatments and the CT treatment. The findings of this study suggest that TRP could be supplemented at a dose of 20 g·kg–1 to the feed to reduce cannibalism and improve the final survival of helicopter catfish

Multicriteria Evaluation Of Tourism Potential In The Central Highlands Of Vietnam: Combining Geographic Information System (GIS), Analytic Hierarchy Process (AHP) And Principal Component Analysis (PCA)

Tourism potential provides an indication for the tourism development opportunities of regions and sites. This paper deals with a multicriteria evaluation of the tourism potential in the Central Highlands of Vietnam. The study area is located in the Southeast Asian monsoon tropical climatic zone, and offers both natural and cultural tourism resources. GIS-based cost distance analysis was used to calculate the travel time along the road and using other transportation networks. Then an Analytic Hierarchy Process (AHP) was applied to determine a weighting coefficient for each criterion in multicriteria evaluation. Principal Component Analysis (PCA) was processed next to AHP, allowing combination of the internal and external tourism potentials of the considered sites. Both AHP and PCA approaches were based on a certain number of alternatives, and take multiple criteria and conflicting objectives into consideration. The results show that the Central Highlands have considerable potential for tourism development at 99 potential eco-tourism sites and 45 potential cultural tourism sites. However, the region is now faced with poor tourism infrastructure with low external potential. An improvement of tourism infrastructure, service quality, and strengthened linkages with other tourist sites is indicated to diversify the tourism products and increase the attractiveness of regional destinations

ẢNH HƯỞNG CỦA CHẾ PHẨM BOKASHI TRẦU ĐẾN TĂNG TRƯỞNG, TỶ LỆ SỐNG VÀ HỆ SỐ CHUYỂN ĐỔI THỨC ĂN CỦA CÁ CHẠCH BÙN (Misgurnus anguillicaudatus Cantor, 1842)

Tóm tắt: Thí nghiệm được tiến hành trong bể xi măng với 3 nghiệm thức (NT) được bổ sung các mức bokashi trầu khác nhau vào thức ăn của cá (NT1–10 mL/kg, NT2–15 mL/kg và NT3–20 mL/kg) và nghiệm thức đối chứng không bổ sung bokashi trầu (ĐC). Con giống có chiều dài trung bình 5,3 cm và trọng lượng trung bình 6,2 gam, được thả với mật độ 100 con/m3. Sau 4 tháng thí nghiệm nuôi cá Chạch bùn thu được một số kết quả sau: Các yếu tố môi trường (Nhiệt độ, pH, DO và NH3) trong thời gian thí nghiệm nằm trong ngưỡng cho phép đối với cá. Kết quả về tăng trưởng cho thấy chế phẩm bokashi trầu đã ảnh hưởng đến tăng trưởng của cá (p < 0,05), ở NT3 cá tăng trưởng nhanh nhất, tiếp đến là NT2, NT1 và cuối cùng là nghiệm thức ĐC. Tỷ lệ sống của cá Chạch bùn cao ở NT2 và NT3, lần lượt là 89,4 % và 89,6 %, tiếp đến là NT1 88,3 % và nghiệm thức ĐC cho tỷ lệ sống thấp nhất 82,5 % (p < 0,05). Hệ số chuyển đổi thức ăn (FCR) ở NT3 là 1,73 thấp hơn so với NT2 là 1,74, NT1 là 1,79 và nghiệm thức ĐC là cao nhất là 1,84                       (p < 0,05). Kết quả nghiên cứu cho thấy bổ sung chế phẩm bokashi trầu 15–20 mL/kg thức ăn giúp cải thiện tăng trưởng, tỷ lệ sống và hệ số chuyển đổi thức ăn của cá Chạch bùn (p < 0,05).Từ khóa: bokashi trầu, cá Chạch bùn, tăng trưởng, tỷ lệ sốn