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Comparative Study on Thyristor and Rectifier Circuit Based DC Motor Control with Improved Power Factor and Total Harmonic Distortion
Salma Nazia Rahman,
Tanzina Akter,
Mirza Muhammad Yeamin Hossain,
Md. Abdullah Al Mahmud
Issue:
Volume 9, Issue 2, December 2020
Pages:
31-41
Received:
17 March 2020
Accepted:
31 March 2020
Published:
5 August 2020
Abstract: DC motor is used in many industrial applications. Because it has versatile control characteristics. With the increasing use of power semiconductor units, the speed control of the DC motor is increasingly getting sophisticated and precise. The DC motor can control by various methods, which is as field control, armature voltage control, armature resistance control. The speed of the DC motor is controlled by controlling the armature voltage. Armature voltage is controlled using different single-phase AC/DC converter. Half converter, semi converter, full converter, and dual converter are some of the thyristor-based circuits, which are used for speed control of DC motor. But using power electronics devices causes power factor and total harmonics distortion problem. Different types of Rectifier circuit with filter capacitor is used to reduce the problem of power factor and total harmonics distortion like Conventional single-phase diode rectifier with filter capacitor, single-phase diode rectifier with LC filter, single-phase diode rectifier circuit with series input resonant filter, Single phase diode rectifier circuit with improved parallel input resonant filter. In this paper, we do a comparative analysis of controlling DC motor with improved PF and THD.
Abstract: DC motor is used in many industrial applications. Because it has versatile control characteristics. With the increasing use of power semiconductor units, the speed control of the DC motor is increasingly getting sophisticated and precise. The DC motor can control by various methods, which is as field control, armature voltage control, armature resi...
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Classical Image Based Classification of Coffee Beans on Their Botanical Origins in Tongo and Wambara, Benishangul Gumuz, Ethiopia
Lamessa Dingeta Olika,
Dejenie Demisse Amberber
Issue:
Volume 9, Issue 2, December 2020
Pages:
42-48
Received:
19 June 2020
Accepted:
29 July 2020
Published:
13 August 2020
Abstract: Ethiopia is a homeland of coffee. Coffee is a major export commodity of Ethiopia, which has a significant role in earning foreign currency. This research was conducted with the objective of developing an appropriate computer routine algorithm that can characterize different varieties of Beneshanguel coffee based on their growing region. Imaging techniques were employed to automatically classify the coffee bean samples according to provenance in Beneshanguel (Tongo and Wombera) which corresponds to their botanical origins. Important coffee bean features, namely, color, shape and size and texture were extracted from 100 images (50 images from each location). For the purpose of classification, altogether 24 features (12 colors, 6 shapes and size and 6 textures) were extracted from images of the coffee samples from the two locations. Artificial neural network (ANN) was employed to automatically categorize the coffee beans according to their provenance. We have compared classification approaches of Neural Network classifiers were employed based on the features used for color, morphology (shapes and size), texture, and the combination of morphology and color respectively. To evaluate the classification accuracy, from the total of 100 sample images of the training 70% (70 images), validation 20% (20 images) and testing 10% (10 images) data. Classification scores of 93%, and 99.3% were achieved for color, morphology, texture and a combination of morphology and color features, respectively. The classification results of the network indicated that morphology and a combination of morphological and color features exhibited the highest accuracy. In conclusion, the results of this study have revealed that imaging technique could be used as the most effective method to determine coffee bean qualities for export. However, it is suggested that the repeatability of this coffee quality testing method be validated using a large data set before employing the algorithm for the purpose of classifying coffee beans as a daily routine.
Abstract: Ethiopia is a homeland of coffee. Coffee is a major export commodity of Ethiopia, which has a significant role in earning foreign currency. This research was conducted with the objective of developing an appropriate computer routine algorithm that can characterize different varieties of Beneshanguel coffee based on their growing region. Imaging tec...
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Delay Based Auto-Calibrated PVT Monitor System and Method
Alexandro Giron,
Esteban Martinez,
Victor Avendaño
Issue:
Volume 9, Issue 2, December 2020
Pages:
49-58
Received:
24 March 2020
Accepted:
15 April 2020
Published:
3 September 2020
Abstract: In this paper, an auto-calibrated PVT (process, voltage, temperature) monitoring system based on delay chains and flip-flops is presented. The system and method are proposed to be used by IP’s (Intellectual property) that require to monitor PVT conditions during its operation and depending on the detected changes be configurable or adaptive. The methodology is based on embedded PVT monitors that sense when the propagation delay variation in standard cells reaches a certain threshold. The system implementation is intended to be done since the RTL (register transfer level) design stage to avoid or reduce the full custom design effort. The PVT monitors are built using buffers from a technology design kit. The information of the PVT monitors is sent to a logic module that calibrates the monitors to choose the best monitoring option depending on the PVT corner, available clock, and standard cells delay. The system includes also a logic module that collects and sends the data inside or outside the chip, in parallel or serial modes. Characterization results of the PVT monitors are presented including different delay chains, and clock combinations trough different PVT corners. This system is intended to detect the change of the propagation delay in the cells due to the PVT conditions combined, and not to provide the stand-alone value of voltage, temperature, or process. Otherwise, one of the reasons for this proposal is to avoid the use of individual sensors.
Abstract: In this paper, an auto-calibrated PVT (process, voltage, temperature) monitoring system based on delay chains and flip-flops is presented. The system and method are proposed to be used by IP’s (Intellectual property) that require to monitor PVT conditions during its operation and depending on the detected changes be configurable or adaptive. The me...
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