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The SG6043 airfoil model is well known for its high aerodynamic efficiency and it is suitable for designing small wind turbine blades. This paper determined the optimal blade configurations using only the SG6043 airfoil model with ten different lengths from 1 m to 10 m. Then, it proposed the most suitable model for a rated wind speed of 5 m/s in Vietnam. The chord and twist values of each blade’s part were optimized by using the Betz optimization method (BOM) in the Qblade open software. Several important characteristic quantities such as lift coefficient (Cl), drag coefficient (Cd), power factor (Cp) and power (P) of the different blade configurations are determined by using a combination of both XFLR5 code and Qblade software. After that, parameters related to operation such as pitch angle and rotation speed of the rotor were also investigated to find the operating conditions for the best efficiency of wind energy exploitation. The obtained results show that the Cp of the blades has a maximum value of about 0.476 and the P has a value of up to 95.319 kW in operating conditions with a wind speed range between 1 m/s and 10 m/s. In addition, the ratios of power to blade surface area (P/S) and the ratios of power to blade volume (P/V) at the wind speed of 5 m/s were also investigated. The results show that rotors with blades ranging from 3 m to 5 m will give much higher P/S and P/V values than other blade configurations under these operating conditions. This emphasizes that these blade configurations will bring more economic benefit because they will consume less material and reduce production time while still ensuring the required capacity value. Finally, the 5 m blade rotor with a capacity of 2.750 kW at a rated wind speed of 5 m/s was proposed as the rotor suitable for individual household use. This design can help millions of Vietnamese households be proactive in their power source, thereby contributing to the significant reduction of CO2 emissions from coal-fired power plants.

Objective. This study examined bacterial skin and soft tissue infections (SSTIs) in pediatric patients at a hospital in Vietnam. Methods. An April 2022-June 2023 prospective obsevational study at a Tertiary Paediatric Centre in Vietnam. Results. From We analyzed 87 cases and found that the greatest occurrence rates were reported during the summer season. Common symptoms were fever, edema, and lower leg involvement. Curiously, although blood cultures seldom verified the offender, Staphylococcus aureus was the most common cause. Additionally, the study found that children with infections including pus were administered a more extended course of antibiotics. Approximately one-third of the patients underwent surgical procedures, and most of them were administered intravenous antibiotics. Fortunately, all the youngsters made a full recovery. Conclusions. In summary, the results indicate that children with purulent SSTIs, primarily attributed to Staphylococcus aureus , may need longer courses of antibiotics. Intravenous antibiotic administration emerged as the predominant therapeutic modality.

The goal of reducing greenhouse gas emissions and energy transition has created many favorable conditions to promote solar power generation technology. However, from a technical perspective, integrating solar power into the power grid poses many challenges in grid operation. This study investigates the impact of rooftop solar power in terms of power quality in the urban distribution grid in Vietnam. The current study simulated a typical low-voltage distribution grid with single-phase and three-phase loads to evaluate important power quality issues, such as Total Harmonic Distortion (THD) of voltage and current, voltage unbalance, and voltage rises. A grid simulation grid was developed in Matlab/Simulink under different conditions for the penetration level of solar power and the daily variation of loads. These indexes were compared with the limits specified in Vietnamese standards and the relevant international standards of IEEE and IEC. Compliance with the provisions of these standards was provided, even in the case of solar power systems with a high level of penetration into Vietnam's urban distribution grid.

In Vietnam, comprehensive measures are required to accommodate and encourage the potential development of electric two-wheelers in urban traffic and the rooftop solar power potential. In the case of PV-integrated electric two-wheeler charging stations, numerous vehicles charging simultaneously may trigger very high peak loads which adversely impacts other loads and the distribution grid. In this study, an optimal valley-filling algorithm for electric two-wheeler charging stations is proposed. The proposed algorithm can update the variation of available vehicles as well as the dynamic changes in the energy level of individual E2Ws at each time slot. The simulation results proved that the proposed method can effectively perform valley filling, significantly improving the total load profile compared to uncontrolled charging and average charging schemes.

This paper presents the effectiveness of the ensemble empirical mode decomposition-long short-term memory (EEMD-LSTM) model for short term load prediction. The prediction performance of the proposed model is compared to that of three other models (LR, ANN, LSTM). The contribution of this research lay in developing a novel approach that combined the EEMD-LSTM model to enhance the capability of industrial load forecasting. This was a field where there had been limited proposals for improvement, as these hybrid models had primarily been developed for other industries such as solar power, wind power, CO2 emissions, and had not been widely applied in industrial load forecasting before. First, the raw data was preprocessed using the IQR method, serving as the input for all four models. Second, the processed data was then used to train the four models. The performance of each model was evaluated using regression-based metrics such as mean absolute error (MAE) and mean squared error (MSE) to assess their respective output. The effectiveness of the EEMD-LSTM model was evaluated using Seojin industrial load data in Vietnam, and the results showed that it outperformed other models in terms of RMSE, n-RMSE, and MAPE errors for both 1-step and 24-step forecasting. This highlighted the model's capability to capture intricate and nonlinear patterns in electricity load data. The study underscored the significance of selecting a suitable model for electricity load forecasting and concluded that the EEMD-LSTM model was a dependable and precise approach for predicting future electricity assets. The model's robust performance and accurate forecasts showcased its potential in assisting decision-making processes in the energy sector.

Small wind turbines operating in low wind speed regions have not had any significant success. In addition, small wind speed regions occupy a large area of the world, so they represent a potential area for installing small wind turbines in the future. In this paper, a method to design an efficient airfoil for small wind turbines in low wind speed conditions using XFLR5 and CFD simulations is implemented. Because the impact of the airflow on the blade surface under low Re number conditions can change suddenly for small geometries, designing the airfoil shape to optimize the aerodynamic performance is essential. The tuning of the key geometric parameters using inversion techniques for better aerodynamic performance is presented in this study. A two-dimensional model was used to consider the airflow on the airfoil surface with differences in the angle of attack. The original S1010 airfoil was used to design a new airfoil for increasing the aerodynamic efficiency by using V6.57 XFLR5 software. Subsequently, the new VAST-EPU-S1010 airfoil model was adjusted to the maximum thickness and the maximum thickness position. It was simulated in low wind speed conditions of 4–6 m/s by a computational fluid dynamics simulation. The lift coefficient, drag coefficient, and CL/CD coefficient ratio were evaluated under the effect of the angle of attack and the maximum thickness by using the k-ε model. The simulation results show that the VAST-EPU-S1010 airfoil achieved the greatest aerodynamic efficiency at an angle of attack of 3°, a maximum thickness of 8%, and a maximum thickness position of 20.32%. The maximum value of CL/CD of the new airfoil at 6 m/s was higher than at 4 m/s by about 6.25%. [ABSTRACT FROM AUTHOR]

In developing countries as well as in Vietnam, infrastructure for two-wheeled electric vehicles is necessary but has not drawn much attention. Sustainable transportation in urban traffic requires sustainable solutions to first-mile/last-mile services which are essential for eco-friendly and efficient connection to the public transport system. Hence, electric two-wheeler charging stations which coordinate charging a large number of electric bicycles/electric motorcycles at public parking or transit hubs should be considered. In this study, the authors propose a novel approach to effectively allocate power to electric two-wheelers in a charging station which is interconnected with the distribution grid, a photovoltaic system and conventional loads of a building. With a three-stage of allocation, the proposed algorithm proves its effectiveness in reducing load variance as well as peak shaving and valley filling while relieving the complexity of solving multivariable optimal problems. The idea also contributes to increasing the penetration rate of both electric vehicles and distributed photovoltaic sources while alleviating adverse effects of these emergent factors.

Offshore wind energy is a renewable energy source that is developing fast. It is considered to be the most promising energy source in the next decade. Besides, the expanding trend for this technology requires the consideration of diversified seabeds. In deep seabeds, floating offshore wind technology (FOWT) is needed. For this latter technology, such as for conventional WT, we need to consider aspects related to performance, aerodynamic force, and forces during operation. In this paper, a two-bladed downwind wind turbine model is utilized to conduct experiments. The collective pitch and cyclic pitch angle are adjusted using swashplated equipment. The fluid forces and moments acting on the rotor surface are measured by a six-component balancing system. By changing the pitch angle of the wind turbine blades, attempts are made to manage the fluid forces generated on the rotor surface. Under varied uniform wind velocities of 7, 8, 9, and 10 m/s, the effect of collective pitch control and cyclic pitch control on the power coefficient and thrust coefficient of FOWT is then discussed. Furthermore, at a wind speed of 10 m/s, both the power coefficient and loads are investigated as the pitch angle and yaw angle change. Experimental results indicate that the combined moment magnitude can be controlled by changing the pitch-angle amplitude. The power coefficient is adjusted by the cyclic pitch-angle controller when the pitch-angle phase changes. In addition, the thrust coefficient fluctuated when the pitch angle changed in the oblique inflow wind condition.

Topography is one of the important factors directly related to the distribution of wind resources, so it plays an important role in determining the layout and operation efficiency of wind power farms. In this research, we use a combination of Computational Fluid Dynamics (CFD) method and Geographic Information Systems (GIS) data to determine suitable locations for building wind turbines in complex terrain conditions. The selected region to build the analytical model is an area with many hills and mountains adjacent to the East Sea, in Thuan Nam and Ninh Phuoc districts, Ninh Thuan province. The first part, this article will provides a general method for determining the best locations for installation of wind turbines according to specific terrain conditions. Then, apply this method to build accurate 3D models for the area, the models are meshed by hexagonal elements combined with tetrahedron elements with side lengths of 200m. The results obtained from the models are the distributions of wind speed by altitude at specific locations such as mountain peaks, mountain slopes, valleys of the area pointed out. Based on these results, the locations with high and stable wind speed, suitable for wind turbine operation are suggested. In addition, the article also presents some locations where wind with high turbulence or eddy winds may appear, which may adversely affect turbine performance. Finally, the paper gives an optimal location map for a wind farm with a capacity of less than 100MW using a turbine with a 4MW capacity.

Increasing offshore wind farms are rapidly installed and planned. However, this will pose a bottle neck challenge for long-distance transmission as well as inherent variation of their generating power outputs to the existing AC grid. VSC-HVDC links could be an effective and flexible method for this issue. With the growing use of voltage source converter high-voltage direct current (VSC-HVDC) technology, the hybrid VSC-HVDC and AC system will be a next-generation transmission network. This paper analyzes the contribution of the multi VSC-HVDC system on the AC voltage stability of the hybrid system. A key contribution of this research is proposing a novel adaptive control approach of the VSC-HVDC as a so-called dynamic reactive power booster to enhance the voltage stability of the AC system. The core idea is that the novel control system is automatically providing a reactive current based on dynamic frequency of the AC system to maximal AC voltage support. Based on the analysis, an adaptive control method applied to the multi VSC-HVDC system is proposed to realize maximum capacity of VSC for reactive power according to the change of the system frequency during severe faults of the AC grid. A representative hybrid AC-DC network based on Germany is developed. Detailed modeling of the hybrid AC-DC network and its proposed control is derived in PSCAD software. PSCAD simulation results and analysis verify the effective performance of this novel adaptive control of VSC-HVDC for voltage support. Thanks to this control scheme, the hybrid AC-DC network can avoid circumstances that lead to voltage instability.

DC distribution grids are increasingly a promising solution for wind and solar integration due to good matching with DC output voltage such as photovoltaic (PV) array systems, distributed battery storage systems (BESS) and electric vehicles. To overcome the control problems involving coordination control schemes of multi-BESSs in real-time as well as operation strategies of DC grids in the long-term, this paper presents the effective adaptive coordinated droop control of multi-battery energy storage systems (MBESSs) in DC distribution grids. The adaptive coordinated droop is proposed according to the available energy levels in BESSs. With the proposed method, the dual-objectives, which are stabilization of DC voltages especially through disturbance for instance outage of BESS and enhancement of State of Charge (SOC)-balance speed among BESSs, can be achieved. Analytical derivations are established to investigate the impacts of the adaptive method. Meanwhile, the influence of the proposed method on the stability is presented.

This paper deals with the planar Hall effect (PHE) of Ta(5)/NiFe([t.sub.F])/Cu(1.2)/NiFe([t.sub.p])/IrMn(15)/Ta(5) (nm) spin-valve structures. Experimental investigations are performed for 50 [micro]m x 50 [micro]m junctions with various thicknesses of free layer ([t.sub.F] = 4, 8, 10, 12, 16, 26 nm) and pinned layer ([t.sub.p] = 1, 2, 6, 8, 9, 12 nm). The results show that the thicker free layers, the higher PHE signal is observed. In addition, the thicker pinned layers lower PHE signal. The highest PHE sensitivity S of 196 [micro]V/(kA/m) is obtained in the spin-valve configuration with [t.sub.F] = 26 nm and [t.sub.p] = 1 nm. The results are discussed in terms of the spin twist as well as to the coherent rotation of the magnetization in the individual ferromagnetic layers. This optimization is rather promising for the spintronic biochip developments. Index Terms--Biosensors, Hall effect, magnetization reversal, magnetoresistance, magnetoresistive devices.

Objective: To explore the association between high-risk fertility behaviours and the likelihood of chronic undernutrition, anaemia and the coexistence of anaemia and undernutrition among women of reproductive age.Design: The 2011 Bangladesh Demographic and Health Survey, conducted from 8 July to 27 December 2011.Setting: Selected urban and rural areas of Bangladesh.Subjects: A total of 2197 ever-married women living with at least one child younger than 5 years. Exposure was determined from maternal reports of high-risk fertility behaviours. We considered three parameters, maternal age at the time of delivery, birth order and birth interval, to define the high-risk fertility behaviours. Chronic undernutrition, anaemia and the coexistence of anaemia and undernutrition among women were the outcome variables.Results: A substantial percentage of women were exposed to have a high-risk fertility pattern (41·8 %); 33·0 % were at single high-risk and 8·8 % were at multiple high-risk. After adjusting for relevant covariates, high-risk fertility behaviours were associated with increased likelihood of chronic undernutrition (adjusted relative risk; 95 % CI: 1·22; 1·03, 1·44), anaemia (1·12; 1·00, 1·25) and the coexistence of anaemia and undernutrition (1·52; 1·17, 1·98). Furthermore, multiple high-risk fertility behaviours appeared to have more profound consequences on the outcome measured.Conclusions: Maternal high-risk fertility behaviours are shockingly frequent practices among women in Bangladesh. High-risk fertility behaviours are important predictors of the increased likelihood of women's chronic undernutrition, anaemia and the coexistence of anaemia and undernutrition. [ABSTRACT FROM AUTHOR]

Violence against children within the family is one of the most common forms of child maltreatment. We used data from the 2011 Vietnam MICS to examine association between the violent disciplinary practices and socio-demographic factors among Vietnamese mothers/primary care givers. The prevalence of violent disciplinary practices among mothers/primary caregivers was 72.9%. Older women (AOR 0.7, 95% CI 0.5-0.9), having higher education (AOR 0.7, 95% CI 0.6-0.9), belonging to richest quintile (AOR 0.7, 95% CI 0.5-0.9) were less likely to have violent disciplinary practices. Other factors were likely associated with higher violent disciplinary practices included having 2 or 3 or more children, and negative attitudes towards partner violence. Importantly, women who had negative attitudes towards violent discipline were more than three times more likely to have violent disciplinary practices. Developing strategies that include the above interventions could play a crucial role in achieving the decrease violent disciplinary practices in Vietnamese caregivers. [ABSTRACT FROM AUTHOR]