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The study uses the green phosphor of Ca2SiO4:Eu2+ to achieve the color constancy for the dual-film remote phosphor white-LED model at low as well as big CCTs. The utilized green phosphor Ca2SiO4:Eu2+ was prepared using the water-soluble-silicon liquid phase precursor method with the doped Eu2+ ion concentration of 3 mol%. The Ca2SiO4:Eu2+ phosphor emits strong green light with emission intensity focused at 502 nm wavelength, and a wide stimulation band of colors of 225 nm – 450 nm. After applying the Ca2SiO4:Eu2+ green phosphor and modifying its concentration, the modified color and luminous performances can be observed. The better color uniformity and higher luminescence efficiency can be obtained by increasing the percentage of Ca2SiO4:Eu2+ in the phosphor configuration. Meanwhile, the color rendering metrics tend to reduce slightly when the concentration of Ca2SiO4:Eu2+ is over 10% wt.

The paper presents the results of determining the spawning grounds of some fish species in Nha Trang bay MPA, which were sampled in 9/2018, 11/2018, 5/2019 and 7/2019. The analysis results are based on the distribution of the general density and the developmental stages, analysis of decision trees from egg density, location of stations and months by CHAID (Chi-square Automatic Interaction Detector), allowing a relatively accurate estimate of the spawning ground of the red anchovy (Encrasicholina punctifer Fowler, 1938) and the species of the genus Scarus. As a result, the main spawning grounds for red anchovy were the east of Hon Rua and the northeast of Hon Tam and that of Scarus is the southwest of Hon Mun island.

Three specimens of Bathycongrus bleekeri were collected during the survey in 2015 and 2017. The newly recorded species is described herein, a small, moderately elongate species of Bathycongrus with head and body compressed; vertical fins without black mark; tail slender, attenuated, but not filiform; trunk length 1.2 times greater than head length; teeth small, conical, in about three-four rows on jaws, in a small triangular patch on vomer; 28–29 preanal vertebrae, total of 111–113 vertebrae; 26–28 preanal lateral-line pores. Additional data on the morphology and distribution of the species increases the total number of known species in the family Congridae in Vietnamese waters to twelve.

This paper presents the Sensorless Speed control of the Induction Motor (IM) in Direct Field Oriented Control (DFOC) modeling based on the mathematical model of the voltage and current parameter. The first is DFOC controlled modeling of IM, the second presents sensorless speed controller base on RF-MRAS, the third describes the model of the sensorless speed controller based on measured values directly from the induction motor as the voltage and current. The last is simulation results in the Matlab-Simulink environment. These results indicate that this proposed method can determine accurately, very quickly the speed of the induction motor and can be applied in the practice with high reliability, and low cost.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

This paper deals with a novel method to achieve the effective performance of the extended Kalman filter (EKF) for the speedy estimate of an induction motor. The real coding genetic algorithm (GA) is used to optimize the components of the covariance matrix in the EKF, thus ensuring the stability and accuracy of the filter in the speed estimation. The advantage of the proposed method is less dependent on the parameters of the induction motor. The content includes the vector control model for induction motor, the speed estimation by modeling the reference frame-model reference adaptive system (RF-MRAS), the current based-model reference adaptive system (CB-MRAS), and the speed estimation with the EKF optimized by genetic algorithm. Simulative studies on the field-oriented controller (FOC) with different operating conditions are performed in Matlab Simulink when the rotor resistance changes in the current speed estimation methods. The simulation results demonstrate the efficiency of the proposed GA-EKF filter compared with other speed estimation methods of induction motors.

In this paper, the experiments on phosphor-converted LEDs (pc-LEDs) with a correlated color temperature (CCT) of 8500K has been conducted with the scattering enhancement particles (SEPs) to achieve the higher color uniformity and emitted luminous flux of pc-LEDs. Moreover, this paper also introduced about choosing scattering enhancement particles (SEPs), including calcium carbonate (CaCO 3 ) and titania (TiO 2 ), and compared these particles’ properties by adding them into the yellow Y 3 Al 5 O 12 :Ce 3+ phosphor compounding. Afterward, the LightTools program was applied to illustrate the optical simulation, and obtained results was analyzed and verified by applying the Mie-scattering theory. The scattering coefficients, the anisotropic scattering, the reduced scattering, and the scattering amplitudes at 455 nm and 595 nm are included in the scattering computation of SEPs. According to researched results, among the SEPs, TiO 2 particles result in the highest value of color uniformity. However, a rise in their concentration is the cause of a sharp decline in luminous flux. Meanwhile, CaCO 3 particles show the ability of reducing the deviated level in correlated color temperature by 620K if there is employed 30% of CaCO 3 concentration. Hence, CaCO 3 particles are the recommendation for achieving higher chromatic homogeneity and lumen output.

This article demonstrates green-emitting phosphor Gd2O2S:Tb3+ and red-emitting phosphor Y3Al5O12:Cr3+ application in the triple-layer phosphor WLED to enhance optical performance. The arrangement of phosphor layers in the WLED is red phosphor Y3Al5O12:Cr3+ on top, green phosphor Gd2O2S:Tb3+ in the middle, and yellow phosphor YAG:Ce3+ at the bottom. The principal to utilize these phosphor materials is the exploitation of additional red light component and green light component from the green and red phosphor to enrich the color rendering index (CRI) and luminous efficacy. The influences of green phosphor and red phosphor are also estimated with a new quality indicator, the color quality index (CQS). The results show red phosphor Y3Al5O12:Cr3+ enable CRI when its concentration increases while green phosphor exhibits a contrast reaction. Regarding the CQS, the optimal red phosphor concentration for CQS is from 10% to 14%, disregard the concentration in green phosphor. The improvement that applying these two phosphor materials brought comes from limiting the light loss from back-scattering and strengthen chromatic performance through addition red and green light components. These findings can support manufacturers in adapting to modern lighting requirements by improving CRI, CQS and particularly luminous efficiency to more than 40%.

In this article, a free secondary lens is designed for an LED fishing/working lamp (LFWL), which is recommended for the purpose of taking the place of a traditional high-intensity discharge (HID) fishing lamp. To serve the lighting needs of fishing and the on-board activities on fishing boats, the innovative LED lamp is proposed. To make the freeform lens in our optics design process, we depended on Gaussian decomposition. In this way, it is easy to approach the targeted light intensity distribution curve (LIDC) of the LFWL lens. The simulated results show that the performance of the LED fishing/working lamps is much better than that of HID fishing lamps for illumination onboard, on the sea-surface, and underwater. Meanwhile, a lighting efficiency of 91% with the power consumption reduction of more than 50% can be achieved when the proposed LED fishing/working lamps are used instead of the HID fishing lamps.

Induction motors are widely used in an industry and it is necessary to improve control methods for induction motors to increase the efficiency of them. In this paper, sliding mode controllers are proposed instead of traditional PI controllers in vector control of induction motor drives. Moreover, rotor speed is estimated by a sliding mode observer. In addition, the robustness of control and observer algorithms are also proved by Lyapunov’s criterion. The experiments are obtained in different speed changes of an induction motor drive. These experimental results confirm the dynamic properties of a sensorless sliding mode control of an induction motor drive.

This paper presents a solution to deal with a fault of stator current sensors of induction motor (IM) drives by improving the fault tolerant control (FTC) method. The proposed FTC unit including the scheme of three current sensors and their associated observers is used to keep the IMs in the stable operation with any faulty sensor conditions. It consists of three parts: a fault detector, a fault locator, and a stator current reconfiguration. The paper has proposed a new model to estimate stator currents from the differential equations of rotor currents and stator currents for the fault detector. To verify the proposed approach, the simulation in MATLAB/Simulink has been applied and the result has demonstrated the effectiveness of our proposed method.

This paper proposes a method for optimizing the power efficiency of induction motor drives based on the Particle Swarm Optimization algorithm. The power efficiency is improved by adjusting the current magnetization component for a given load torque so that total loss of copper and iron could be minimized. To verify the effectiveness of the proposal method, the simulation in MATLAB/SIMULINK has been implemented and compared with the conventional Rotor Flux Oriented Control. The result shows that the proposed method has improved the power efficiency of the IM drives under the light load regime with a considerable loss reduction.

This paper presents methods for estimating CB-MRAS model parameters such as K1(CB), K2(CB), K3(CB), Ti(CB), KLm, KTr by binary Genetic Algorithm (GA), real number GA, modify GA, and CucKoo Search Algorithm (CSA). The first part of the paper is the vector model of the induction motor and the CB-MRAS model for estimating parameters by the above algorithms; the second part is the detailed way to implement the algorithms; the third part is simulation and as a result of the simulation, the results show that it is possible to estimate the parameters of this model by the modify GA or CSA algorithm.

The paper deals with application of Kalman filter in induction motor drive using pulse-width modulation direct torque control (PWM-DTC). In the first part, the conventional PWM-DTC drive is described and Kalman filter is utilized to filter components of stator current vector those are assumed to be disturbed by white noise. The second part contains simulation results that are obtained in different cases of load torque, process and measurement noise covariances. The integral time absolute error (ITAE) performance index, undershoot, ripple of important quantities are used to compare the conventional drive structure and proposed drive structure with Kalman filter. The simulation results confirm the expected dynamic response of the proposed structure. &nbsp

Improving lighting performance of WLEDs, especially the color quality, has always been a priority in lighting researches. Recently, the conventional remote phosphor configuration is unable to fulfill the needs of the modern lighting market, particularly the high color expression demand has inspired the search for a novel manufacturing procedure. In this study, based on the results from previous studies, the struggles in enhancing lighting performances are pointed out, and a solution, the dual-layer remote phosphor, is proposed from our conducted experiments. Through experiments with NaYF4:Er3+;Yb3+ and Mg2TiO4:Mn4+ phosphors, the dual-layer phosphor is proven to be effective in improving lighting properties such as color rendering index (CRI) and color quality scale (CQS). The research method involves structuring and experimenting with the phosphor configuration of the yellow phosphor YAG:Ce3+ layer with a green NaYF4:Er3+;Yb3+ or a red Mg2TiO4:Mn4+ phosphor layer whose phosphor concentrations are varied. The results show that the red phosphor Mg2TiO4:Mn4+ particles benefit the CRI and CQS because the values of CRI and CQS increase with red phosphor Mg2TiO4:Mn4+ concentration. On the other hand, the green phosphor NaYF4:Er3+;Yb3+ is inferior in improving CRI and CQS but exhibits better luminous flux. Despite being useful in enhancing lighting performance, the phosphor concentration must be kept below a certain level, which will be mentioned in the article, to prevent damages. These results are verified using Mie scattering theory and Lambert-Beer's law and can be utilized in producing WLEDs with high lighting quality. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

The advantage in using a remote phosphor design in a WLED package is the superior luminous flux to that of the conformal and in-cup phosphor geometries. However, the disadvantage is its color quality which is lower than the results from the other two structures. This study suggests using two layers of phosphor for the remote phosphor configuration to improve the light chromaticity, including color rendering index (CRI) and color quality scale (CQS), for WLED packages with color temperature of 8500 K. The main concept of this research is to locate a green Y2O2S:Tb3+ or red ZnS:Sn2+ phosphor layer on the yellow YAG:Ce3+ phosphor film, and then finding a suitable ZnS:Sn2+ concentration to match the highest color quality. The results showed that ZnS:Sn2+ brings great benefits to the increase of CRI and CQS. The greater the ZnS:Sn2+ concentration is, the better the CRI and CQS become owing to the rise of red-light components in WLED packages. Meanwhile, the green Y2O2S:Tb3+ phosphor brings benefits to the lumen output. However, a decrease in the luminescence and chromatic homogeneity appears when the concentrations of ZnS:Sn2+ or Y2O2S:Tb3+ exceed the corresponding level. This finding is verified by applying the Mie-scattering theory and the Lambert-Beer's law. The results of this article are important for the production of high-performance WLEDs in the modern lighting market.

The paper deals with application of fuzzy logic in model-based rotor speed observer for sensorless induction motor drive. Stability analysis of selected observer is described in the first part. Fuzzy logic is applied to adjust parameters of proportional-integral adaption algorithm in rotor speed adaption mechanism. The third part is description of a laboratory stand with the induction motor drive and load unit that was used for an experimental verification of the speed observer with application of fuzzy logic. Expected properties of sensorless control of induction motor drive are confirmed by experimental results.

The paper describes observers using model reference adaptive system for sensorless induction motor drive with the pulse width modulator and the direct torque control under the circumstances of incorrect information of induction motor parameters. An approximation based on the definition of the Laplace transformation is used to obtain initial values of the parameters. These values are utilized to simulate sensorless control structures of the induction motor drive in Matlab-Simulink environment. Performance comparison of two typical observers is carried out at different speed areas and in presence of parameter uncertainty. A laboratory stand with the induction motor drive and load unit is set up to verify the properties of observers. Experimental results confirm the expected dynamic properties of selected observer. Web of Science 16 4 434 426

The paper presents an application of the genetic algorithm for parameter findings in the control structure of the A.C. drive with the vector controlled modeling. The mathematical model of DFOC control of the induction motor with the speed controller is described in the first section. The second part presents the PI-Adaptive model for estimating rotor time constant (T r ), the third is the GA-Adaptive online model combining genetic and adaptive algorithms to estimate rotor time constant, Simulative results in the Matlab-Simulink environment indicate that the value and responsiveness of the T r of GA-Adaptive model are better than PI-Adaptive when the T r values change during operation.

The paper describes a fuzzy speed controller with direct torque control for induction motor drive. Classical PI speed controller with fixed proportional and integral coefficients is not appropriate for exact motor speed regulation in a wide range of reference speed. Fuzzy logic, one of simplest soft computing techniques, can make PI controllers more flexible. In the paper, a simple fuzzy algorithm is proposed for online update coefficients of PI speed controller. The use of a pulse-width modulator in the direct torque control structure is to ensure the constant switching frequency. The control structures of the induction motor drive are implemented into a control system with digital signal processor. Experimental results confirm that speed controller with proposed fuzzy algorithm gives response of actual motor speed with lower overshoot, shorter settling time, and smaller speed accuracy than classical speed controller does.

This paper presents methods for estimating induction motor parameters such as stator resistance, stator inductance, rotor inductance, rotor time constant… by artificial neural network (ANN) and genetic algorithm (GA). The first part is the mathematical basis for estimating motor parameters by neural and genetic algorithms, the second part is the motor model for data collection for estimation, the third part is simulation and As a result of the simulation, the results show that it is possible to accurately estimate the parameters of the induction motor by ANN or GA algorithm.

The paper describes machine model-based speed observers for speed sensorless induction motor drive with direct torque and flux control. However, the wrong information of machine model, especially stator resistance, affects the performance of the direct torque control. Thus, model reference adaptive system based scheme is developed for adapting stator resistance. At first, the sensorless control structures of the induction motor drive are implemented in Matlab-Simulink environment. Then, comparison is done by evaluation of the rotor speed difference. The simulation results confirm that model reference adaptive system speed observers and adaptation technique in control structures are simple to simulate and experiment. By comparison of speed estimators without and with adaptation technique, current based model reference adaptive system observer and Luenberger observer give higher accuracies of the speed estimation, more robust with uncertainty of stator resistance.

The control of induction motor drives constitutes a vast subject, and the technology has further advanced in recent years. Sliding mode controller is control method which is robust to noise and parameter variations. But the sliding mode control is discontinuous control, causing the chattering problem. In this paper, to eliminating above phenomenon, a sigmoid function and gain adaptation for sliding mode controller is developed. Moreover, a sliding mode observer and its applications in the sensor-less control of the induction motor drive are proposed. The mathematical equations of induction motor, sliding mode observer and sling mode control are described in the paper. The stability of observer and controller are proved by Lyapunov’s theory. Simulation results are also presented in the paper.

The paper deals with an application of the genetic algorithm for parameter settings of a speed controller in the control structure of the A.C. drive with the vector controlled induction motor. An induction motor model with the PID speed controller is described in the first section. The second section presents the design of the genetic algorithm for the online tuned PID speed controller. Important simulations with the traditional PID speed controller and the online tuned PID speed controller using the genetic algorithm together with change of parameters and variable disturbances were performed in the Matlab-Simulink environment. The simulation results show that the online tuned PID speed controller using the genetic algorithm produces a much better response of the induction motor speed.

The paper describes speed estimators for a speed sensorless induction motor drive with the direct torque and flux control. However, the accuracy of the direct torque control depends on the correct information of the stator resistance, because its value varies with working conditions of the induction motor. Hence, a stator resistance adaptation is necessary. Two techniques were developed for solving this problem: model reference adaptive system based scheme and artificial neural network based scheme. At first, the sensorless control structures of the induction motor drive were implemented in Matlab-Simulink environment. Then, a comparison is done by evaluating the rotor speed difference. The simulation results confirm that speed estimators and adaptation techniques are simple to simulate and experiment. By comparison of both speed estimators and both adaptation techniques, the current based model reference adaptive system estimator with the artificial neural network based adaptation technique gives higher accuracy of the speed estimation.