Design Low Order Robust Controller for the Generator’s Rotor Angle Stabilization PSS System

The electrical system's problem stabilizes the electrical system with three primary parameters: rotor angle stability, frequency stability, and voltage stability. This paper focuses on the problem of designing a low-order stable optimal controller for the generator rotor angle (load angle) stabilization system with minor disturbances. These minor disturbances are caused by lack of damping torque, change in load, or change in a generator during operation. Using the RH∞optimal robust design method for the Power System Stabilizer (PSS) to stabilize the generator’s load angle will help the PSS system work sustainably under disturbance. However, this technique's disadvantage is that the controller often has a high order, causing many difficulties in practical application. To overcome this disadvantage, we propose to reduce the order of the higher-order optimal robust controller. There are two solutions to reduce order for high-order optimal robust controller: optimal order reduction according to the given controller structure and order reduction according to model order reduction algorithms. This study selects the order reduction of the controller according to the model order reduction algorithms. In order to choose the most suitable low-order optimal robust controller that can replace the high-order optimal robust controller, we have compared and evaluated the order-reducing controllers according to many model order reduction algorithms. Using robust low-order controllers to control the generator’s rotor angle completely meets the stabilization requirements. The research results of the paper show the correctness of the controller order reduction solution according to the model order reduction algorithms and open the possibility of application in practice. Doi: 10.28991/esj-2021-01299 Full Text: PD

On tracking control problem for polysolenoid motor model predictive approach

The Polysolenoid Linear Motor (PLM) have been playing a crucial role in many industrial aspects due to its functions, in which a straight motion is provided directly without mediate mechanical actuators. Recently, with several commons on mathematic model, some control methods for PLM based on Rotational Motor have been applied, but position, velocity and current constraints which are important in real systems have been ignored. In this paper, position tracking control problem for PLM was considered under state-independent disturbances via min-max model predictive control. The proposed controller forces tracking position errors converge to small region of origin and satisfies state including position, velocity and currents constraints. Further, a numerical simulation was implemented to validate the performance of the proposed controller

Effect of Hydrolysis on Tannin and Carotenoid Contents, and Antioxidant Activity of Pouteria campechiana

The medicinal properties of Pouteria campechiana fruit in Vietnam currently have not been studied much. This study was conducted to evaluate hydrolysis's effect on the carotenoid, tannin, and antioxidant activity through the correlation between IC50 and TPC values of Pouteria campechiana extract. This study examined hydrolysis conditions, such as enzyme type, enzyme concentration, temperature, and hydrolysis time. Experimental results showed that at pectinase enzyme concentration of 0.6 wt%, cellulase enzyme concentration of 0.6 wt%, at hydrolysis temperature of 600C, and 65 minutes for hydrolysis, the study found carotenoid of 115.14±4.14 (µg/g) and tannin of 45.88±2.37 (mgTAE/g)in the extract. IC50 value (7.82±0.21 mg/mL) and TPC content were highly correlated (R2=0.98). This study's results contributed to the provision of valuable scientific data on Pouteria campechiana fruit, especially for the food industr

A cross-sectional study of the antibiotic resistant prevalence of ESBL-producing Enterobacteriaceae in Vietnam

Introduction: Antibiotic resistance in Enterobacteriaceae producing extended spectrum beta-lactamase (ESBL) is increasing. Accurate evaluation of antibiotic resistance rates in various categories of bacteria assists medical physicians in recommending suitable indications for their medical problems, improving treatment efficiency, and minimizing dangers for patients. As a result, we undertook this research to assess the prevalence of ESBL-producing Enterobacteriaceae as well as the rate of antibiotic resistance in ESBL-producing Enterobacteriaceae. Methods: A cross-sectional study was conducted on 2716 patients at the An Giang Central General Hospital from June 2020 to June 2021. Data collection was based on interviews and used SPSS 18.0 and GraphPad Prism 9 for data analysis and presentation. Samples included urine, blood, sputum, and pus. Samples were treated with the Phoenix 100 automated machine to separate and identify samples. Results: The highest rate was 64.8% for Escherichia coli, followed by 30.2% for Klebsiella pneumoniae. Proteus mirabilis and Klebsiella oxytoca were found in 4.5% and 0.6% of the samples, respectively. Ampicillin resistance was greatest in E. coli (96.5%), K. pneumonia (92.4%), and K oxytoca (83.3%). The frequency of resistance to the other antibiotics was likewise extremely high, approaching 60%. Tobramycin, Amoxicillin/Clavulanate, Cefoxitin, and Nitrofurantoin were totally resistant to K. oxytoca in the ESBL-producing group. E. coli and K. pneumoniae with ESBL-producing genes also have a high antibiotic resistance rate of more than 50%. Conclusion: E. coli was the most common pathogenic bacteria. Most of the species of bacteria resisted Ampicillin

CSI-based versus RSS-based Secret-Key Generation under Correlated Eavesdropping

Physical-layer security (PLS) has the potential to strongly enhance the overall system security as an alternative to or in combination with conventional cryptographic primitives usually implemented at higher network layers. Secret-key generation relying on wireless channel reciprocity is an interesting solution as it can be efficiently implemented at the physical layer of emerging wireless communication networks, while providing information-theoretic security guarantees. In this paper, we investigate and compare the secret-key capacity based on the sampling of the entire complex channel state information (CSI) or only its envelope, the received signal strength (RSS). Moreover, as opposed to previous works, we take into account the fact that the eavesdropper's observations might be correlated and we consider the high signal-to-noise ratio (SNR) regime where we can find simple analytical expressions for the secret-key capacity. As already found in previous works, we find that RSS-based secret-key generation is heavily penalized as compared to CSI-based systems. At high SNR, we are able to precisely and simply quantify this penalty: a halved pre-log factor and a constant penalty of about 0.69 bit, which disappears as Eve's channel gets highly correlated

The effects from the United States and Japan to emerging stock markets in Asia and Vietnam

The subprime mortgage crisis in the United States (U.S.) in mid-2008 suggests that stock prices volatility do spillover from one market to another after international stock markets downturn. The purpose of this paper is to examine the magnitude of return and volatility spillovers from developed markets (the U.S. and Japan) to eight emerging equity markets (India, China, Indonesia, Korea, Malaysia, the Philippines, Taiwan, Thailand) and Vietnam. Employing a mean and volatility spillover model that deals with the U.S. and Japan shocks and day effects as exogenous variables in ARMA(1,1), GARCH(1,1) for Asian emerging markets, the study finds some interesting findings. Firstly, the day effect is present on six out of nine studied markets, except for the Indian, Taiwanese and Philippine. Secondly, the results of return spillover confirm significant spillover effects across the markets with different magnitudes. Specifically, the U.S. exerts a stronger influence on the Malaysian, Philippine and Vietnamese market compared with Japan. In contrast, Japan has a higher spillover effect on the Chinese, Indian, Korea, and Thailand than the U.S. For the Indonesian market, the return effect is equal. Finally, there is no evidence of a volatility effect of the U.S. and Japanese markets on the Asian emerging markets in this study