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Introduction: Obesity is acknowledged to be a significant risk factor for mortality in patients with COVID-19. At primary healthcare center, early stratification of high-risk patients is critical in order to provide effective management. There is limited research available in Vietnam concerning the relationship between obesity as defined by Asian- standards and pulmonary damage. Our goal was to find the correlation between the obesity status index by Asian-standardized BMI and the severity of lung injury on chest radiographs patients with COVID-19 in the Vietnamese field hospital. Methods: A total of 279 confirmed COVID-19 patients (118 males and 161 females) patients were recruited in our study. Two internal medicine physicians independently evaluated chest X-rays using the Brixia score system to assess the severity of lung disease, then agreed. The probability of Brixia scores per chest X-ray film was modeled using Poisson regression with gender and Asian-standardized BMI as predictors. Results: The study revealed that the median age of our study was 59 years, and the mean BMI was 24.6 ± 3.4 kg/m2. The Pearson correlation between the Brixia score and the BMI was 0.25 with a p-value < 0.05. Both men and women showed that the obese group had the highest Brixia scores. There was a statistically significant difference between Brixia scores of male patients between the normal and obese groups (p-value =0.0446). Poisson regression showed that as the BMI increased, the probability of a higher Brixia score also increased. Conclusions: According to the findings, the higher the BMI value of a patient, the higher the Brixia score for chest X-rays. This result was recorded in both genders, but more significantly in men.

This paper concerned with the development and implementation of smart street lighting control system based using Led lamp and Lora Wireless communication. Smart street lamps have been developed for over several years. These technologies have played an important role in urban safety, energy conservation. Currently, a traditional street lights are automatically turn on or off based on timer or day/night sensor. LEDs are now the standard replacement for legacy lighting in most cities around the world. At the same time, smart controls are becoming more mainstream and are increasingly installed alongside LED deployments. Recently, the conventional light sources are replaced by Led, which have so many advantages such as: energy savings, long lifetime, high reliability, pure light color, fast response, and friendliness to the environment. Furthermore, the intensity of the LED can be controlled easily. In this paper, the smart lighting system is designed to control and monitor devices via wireless transmission frequencies below 1 GHz. The system will include many types of devices connected to each other by a gateway. The transmit distance is about 2km in the urban area and up to 5km in rural area. The proposed smart street public lighting provides some advantages features such as: Automatic mode, Remote control mode, Connection disconnection mode, Manual direct operation mode. The smart lighting system has been built at Ho Chi Minh City University of Technology to meet the standards for data transmission. And some experimental resutls are provided to show the effectiveness of the porposed system.

This paper presents a new online loss-minimization algorithm in the adaptive control model for speed sensorless based on the Direct Rotor Flux Oriented Control (DRFOC) with optimum flux in the condition of do variable stator resistance. The paper also presents a new approach to develop a reference and adaptive models to estimate the speed and to observe stator resistance change. Simulation results in Matlab Simulink showed good adaptability of the presented model controls even when the stator resistance changes to up 200% of rated. In addition, using the proposed algorithm allows reducing losses and improving efficiency of proposed control model in comparison with DRFOC traditional model for load range 0-70% of the rated. Where the difference of efficient can reach 42%, and the difference in loss to 85%.

This paper presents a DSP based implementation of simple and very useful control algorithm for the real-time efficiency optimization of the indirect vectorcontrolled induction motor drives. Conventional field-oriented induction motor drives operate at rated flux even at low load. To improve the efficiency of the existing induction motors, it is important to regulate the magnetization flux of the motor in the desired operating range. This paper presents techniques for minimizing power loss (the copper and core losses) of induction motor based on determination of an optimum flux level for the efficiency optimization of the vector-controlled induction motor drive. An induction motor (IM) model in d-q coordinates is referenced to the rotor magnetizing current. Thus the decomposition into d-q components in the steady-state motor model can be utilized in deriving the motor loss model. The algorithm offers a fast convergence. The complete closed loop vector control of the proposed LMC-based IM drive is successfully implemented in real-time using digital signal processor DSP TMS320LF2812 for 1HP motor induction motor. The close agreement between the simulation by Matlab/Simulink and the experimental results confirms the validity and usefulness of the proposed techniques. The proposed LMC in a comparison with conventional FOC can reduce total losses from 5% to 67.2% for all load ranges.

This paper presents an implementation of the DC/DC push–pull converter for an uninterruptible power supply (UPS). Some classical DC/DC converters are presented and analyzed for pointing out their advantages and drawbacks. Besides, an original system based on a push-pull converter associated with a dynamic modulation control is chosen. The main advantage is the possibility to control the delivered electric power in a wide range from very low level to high level of voltage within the same basic architecture. It can reduce the switching power losses and increase the power conversion efficiency. This paper proposed a new control scheme of the DC/DC converter and DC/AC inverter. The suggested system consists of a high efficiency DC/DC converter and a singlephase DC/AC inverter has been simulated using Matlab/Simulink and designed basing on the DSP TMS320F28027. Both results show high performances of the DC link and AC load voltages, when load changes from zero to rated. The performance of the proposed system has been verified through a 1kW prototype of the system for a 50 Hz/220-230 VAC load sourcing by two series connected batteries of 12V. The proposed DC/DC converter achieves a high efficiency of 93.0%. The system including the DC/DC converter and DC/AC inverter achieves an efficiency of 91.2% and Total Harmonic Distortion (THD) of AC load voltage reached 1.9%.