Design and Implementation of a Low-cost MOSFET Based Chopper Drive DC Motor Speed Control

Electric drives have numerous applications in diverse areas such as rolling mills, electric trains and robotic manipulators. Inefficient control of motor speed can destroy the equipment itself; even can cause a severe accident. In this project, a low-cost MOSFET based chopper drive DC motor speed control system was designed and implemented. In this system, the feedback voltage from the load controls the speed of the DC motor through speed controller. From the measurement, it is clear that for a maximum rpm of 210, the percentage of error varied from 1.10 to 14.28 for 12 V supply voltage. The total cost of the speed control scheme is only 18 USD. Such a drive will be appropriate for the speed control of DC motor in household to industrial appliances

Estimation of Solar Radiation: An Empirical Model for Bangladesh

This study is carried out to compute empirically global, diffuse and direct solar radiation on a horizontal surface for the ten districts equally distributed all over Bangladesh (20o34΄and 26o34΄north latitude, 88o01΄ and 92o41΄east longitude) as well as to predict correlations for them. For this study, meteorological data for 28 years (between 1980 and 2007) is used which is collected from Bangladesh Meteorological Department. The global radiation in Bangladesh is found to be maximum in the month of April/May and minimum in the month of November/December in all the districts. The values of the correlation coefficients a, b, c, d, c', d', e, f, e' and f' for ten stations of Bangladesh are also evaluated. It is evident that, the values of the coefficient “a” vary from 0.2296 to 0.2569, while the coefficient “b” varies from 0.5112 to 0.5560. The over all mean deviations of the ten values of a and b are 0.2432±0.0136 and 0.5336±0.0224, respectively. The maximum and minimum values of other correlation coefficients c, d, c', d', e, f, e' and f' are (1.5695 and 1.4357), (-1.7210 and -1.9986), (0.4011 and 0.376), (-0.2072 and -0.2510), (-0.3811 and -0.5464), (1.946 and 1.6456), (-0.1206 and -0.1684) and (0.7984 and 0.7000) respectively. Their maximum variations due to location are (1.5022±0.0672), (-1.8598±0.1388), (0.3885±0.0125), (-0.2291±0.0219), (-0.4637±0.0826), (1.7958±0.1502), (-0.1445±0.0239) and (0.7492±0.0492) respectively. ABSTRAK: Kajian ini dibuat secara empirikal mengenai kadar penyebaran secara resapan, global dan langsung radiasi solar, keatas permukaan mendatar untuk sepuluh daerah di seluruh Bangladesh (20o34΄ dan 26o34΄ utara latitud, 88o01΄ dan longitud 92o41΄ timor) dan meramal korelasi mereka. Kajian ini menggunakan data meteorologi selama 28 tahun (antara 1980 dan 2007) yang dikutip dari Jabatan Meteorologi Bangladesh. Radiasi global maksima di Bangladesh adalah pada bulan April / Mei dan minima pada bulan November / Disember di semua daerah. Kajian dibuat mengenai nilai pekali korelasi a, b, c, d, c', d', e, f, e' dan f' bagi sepuluh stesen di Bangladesh. Nilai pekali "a" adalah antara 0.2296 dan 0.2569, manakala pekali "b" adalah antara 0.5112 dan 0.5560. Sisihan min keseluruhan bagi sepuluh nilai a dan b adalah 0.2432 ± 0.0136 dan 0.5336 ± 0.0224. Nilai maksima dan minima pekali korelasi lain c, d, c', d', e, f, e' dan f' adalah (1.5695 and 1.4357), (-1.7210 dan -1.9986), (0.4011 dan 0.376), (-0.2072 dan -0.2510), (-0.3811 dan -0.5464), (1.946 dan 1.6456), (-0.1206 dan -0.1684) dan (0.7984 dan 0.7000). Variasi maksima antara mereka disebabkan lokasi adalah (1.5022±0.0672), (-1.8598±0.1388), (0.3885±0.0125), (-0.2291±0.0219), (-0.4637±0.0826), (1.7958±0.1502), (-0.1445±0.0239) dan (0.7492±0.0492). KEYWORDS: Bangladesh; coefficient; correlation; radiation; sola

Computing the Performance of FFNN for Classifying Purposes

 Classification is one of the most hourly encountered problems in real world. Neural networks have emerged as one of the tools that can handle the classification problem. Feed-Forward Neural Networks (FFNN's) have been widely applied in many different fields as a classification tool. Designing an efficient FFNN structure with the optimum number of hidden layers and minimum number of layer's neurons for a given specific application or dataset, is an open research problem and more challenging depend on the input data. The random selections of hidden layers and neurons may cause the problem of either under fitting or over fitting. Over fitting arises because the network matches the data so closely as to lose its generalization ability over the test data. In this research, the classification performance using the Mean Square Error (MSE) of Feed-Forward Neural Network (FFNN) with back-propagation algorithm with respect to the different number of hidden layers and hidden neurons is computed and analyzed to find out the optimum number of hidden layers and minimum number of layer's neurons to help the existing classification concepts by MATLAB version 13a. By this process, firstly the random data has been generated using an suitable matlab function to prepare the training data as the input and target vectors as the testing data for the classification purposes of FFNN. The generated input data is passed on to the output layer through the hidden layers which process these data. From this analysis, it is find out from the mean square error comparison graphs and regression plots that for getting the best performance form this network, it is better to use the high number of hidden layers and more neurons in the hidden layers in the network during designing its classifier but so more neurons in the hidden layers and the high number of hidden layers in the network makes it complex and takes more time to execute. So as the result it is suggested that three hidden layers and 26 hidden neurons in each hidden layers are better for designing the classifier of this network for this type of input data features

Design architectures of the CMOS power amplifier for 2.4 GHz ISM band applications: An overview

Power amplifiers (PAs) are among the most crucial functional blocks in the radio frequency (RF) frontend for reliable wireless communication. PAs amplify and boost the input signal to the required output power. The signal is amplified to make it sufficiently high for the transmitter to propagate the required distance to the receiver. Attempted advancements of PA have focused on attaining high-performance RF signals for transmitters. Such PAs are expected to require low power consumption while producing a relatively high output power with a high efficiency. However, current PA designs in nanometer and micrometer complementary metal–oxide semiconductor (CMOS) technology present inevitable drawbacks, such as oxide breakdown and hot electron effect. A well-defined architecture, including a linear and simple functional block synthesis, is critical in designing CMOS PA for various applications. This article describes the different state-of-the art design architectures of CMOS PA, including their circuit operations, and analyzes the performance of PAs for 2.4 GHz ISM (industrial, scientific, and medical) band applications

A CMOS power splitter for 2,45 GHz ISM band RFID reader in 0,18 µm CMOS technology

Identifikacija radio frekvencije (RFID) je jedna od najbrže rastućih tehnologija uporabljiva u gotovo svakom sektoru za pohranu i bežično uzimanje podataka. Trenutni napredak u CMOS tehnologiji pomaže znanstvenicima i tehnolozima smanjiti dimenzije i poboljšati funkcionalnost RFID sklopova. U ovom radu ilustrirana je konstrukcija jednog RF-CMOS razdvajača snage električnog kruga u 0,18 µm Silterra RF-CMOS tehnologiji za 2,45 GHz RFID čitač. Wilkinsonov razdjelnik snage izabran je za predloženi razdvajač snage električnog kruga s induktorima i kondenzatorima na čipu. Predloženi razdvajač snage ostvaruje najveći gubitak zbog umetanja od 10 dB. AWR Microwave Office® koristi se za simulaciju električnog kruga i za određivanje njegovih S-parametara. Za konstruiranje induktora s točnim vrijednostima u 2,45 GHz rabljen je Sonnet® dok je Cadence® rabljen za razmještaj kondenzatora i otpornika.Radio frequency identification (RFID) is one of the most rapidly growing technologies to be utilized in almost every sector for storing and retrieving data wirelessly. Current advancements in CMOS technology help the scientists and technologists to reduce the size and improve the functionalities of the RFID circuits. In this paper, the design of an RF-CMOS power splitter circuit in 0,18 µm Silterra RF-CMOS technology is illustrated for a 2,45 GHz RFID reader. Wilkinson power divider is chosen for the proposed power splitter circuit with on-chip inductors and capacitors. The proposed power splitter achieves a maximum insertion loss of 10 dB. AWR Microwave Office® is used for the simulation of the circuit and for determination of its S-parameters. To design the inductors with accurate values in 2,45 GHz Sonnet® is used whereas Cadence® is used for capacitor and resistor layout

A review of chewing detection for automated dietary monitoring

A healthy dietary lifestyle prevents diseases and leads to good physical conditions. Poor dietary habits, such as eating disorders, emotional eating and excessive unhealthy food consumption, may cause health complications. People’s eating habits are monitored through automated dietary monitoring (ADM), which is considered a part of our daily life. In this study, the Google Scholar database from the last 5 years was considered. Articles that reported chewing activity characteristics and various wearable sensors used to detect chewing activities automatically were reviewed. Key challenges, including chew count, various food types, food classification and a large number of samples, were identified for further chewing data analysis. The chewing signal’s highest reported classification accuracy value was 99.85%, which was obtained using a piezoelectric contactless sensor and multistage linear SVM with a decision tree classifier. The decision tree approach was more robust and its classification accuracy (75%–93.3%) was higher than those of the Viterbi algorithm-based finite-state grammar approach, which yielded 26%–97% classification accuracy. This review served as a comparative study and basis for developing efficient ADM systems

RF Systems, Circuits and Components

Radio frequency (RF) refers to frequencies between the upper limit of audio frequencies (> 20 KHz) and the lower limit of infrared frequencies (< 300 GHz). The increased popularity and easy operation of RF devices for different end users and corporate applications such as RFID, Bluetooth, Zigbee and Wi-Fi devices and sensors have raised the demand for small power and less off-chip components that tend to achieve integrated circuits with added security and convenience. Concurrent technologies allow the scientists to reinvent low-power, high-performance and reliable RF systems, circuits and components for many home and commercial applications. The features of RF systems, circuits and components are still being researched and integrated in existing systems to create marketable and potential new RF products for more exciting applications