scholarly journals Operational Transresistance Amplifier-Based Multiphase Sinusoidal Oscillators

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Rajeshwari Pandey ◽  
Neeta Pandey ◽  
Mayank Bothra ◽  
Sajal K. Paul

Multiphase sinusoidal oscillator circuits are presented which utilize Operational Transresistance Amplifier (OTRA) as the active element. The first circuit producesnodd-phase oscillations of equal amplitudes and equally spaced in phase. The second circuit is capable of producingnodd- or even- phase oscillations equally spaced in phase. An alternative approach is discussed in the third circuit, which utilizes a single-phase tunable oscillator circuit which is used to inject signals into a phase shifter circuits. An automatic gain control (AGC) circuit has been implemented for the second and third circuit. The circuits are simple to realize and have a low component count. PSPICE simulations have been given to verify the theoretical analysis. The experimental outcome corroborates the theoretical propositions and simulated results.

2021 ◽  
Vol 11 (13) ◽  
pp. 5793
Author(s):  
Bartosz Dominikowski

The accuracy of current measurements can be increased by appropriate amplification of the signal to within the measurement range. Accurate current measurement is important for energy monitoring and in power converter control systems. Resistance and inductive current transducers are used to measure the major current in AC/DC power converters. The output value of the current transducer depends on the load motor, and changes across the whole measurement range. Modern current measurement circuits are equipped with operational amplifiers with constant or programmable gain. These circuits are not able to measure small input currents with high resolution. This article proposes a precise loop gain system that can be implemented with various algorithms. Computer analysis of various automatic gain control (AGC) systems proved the effectiveness of the Mamdani controller, which was implemented in an MCU (microprocessor). The proposed fuzzy controller continuously determines the value of the conversion factor. The system also enables high resolution measurements of the current emitted from small electric loads (≥1 A) when the electric motor is stationary.


2017 ◽  
Vol 17 (1) ◽  
pp. 66-94
Author(s):  
Ivana Miková

AbstractThe main aim of this paper is to discuss standard explanations of the causes respective to each wave of economic regionalism and to introduce an alternative approach suggesting the existence of a common mechanism driving all three periods of intensified economic integration. This study argues for the general logic to economic regionalism based on the balance mechanism. Proposed mechanism embraces standard theoretical explanations and places them into a broader context of general encompassing logic common to all three occurrences of economic regionalism. For acquiring empirical evidence of this mechanism, all three waves of regionalism and their causes are analysed as well as on one particular case of the third wave of regionalism - ASEAN-China FTA. Central motivation is the existence of plethora of factors leading to the preference of the regional trade strategies in particular time periods without offering explanation common to all three main occurrences of regionalism. However, this study argues that every instance of economic turmoil leads to protectionist tendencies in the form of economic regionalism followed by the multilateral trade liberalisation mitigating negative effects of protectionist tendencies.


2003 ◽  
Author(s):  
M.F. Krol ◽  
Yongqian Liu ◽  
J.J. Watkins ◽  
D.W. Lambert

1957 ◽  
Vol PGBTS-8 (1) ◽  
pp. 6-9
Author(s):  
M. H. Diehl ◽  
W. J. Hoffman ◽  
W. L. Shepard

Author(s):  
ISSRAQ BIN RAMLI ◽  
MOHD ZAKI ABD. RAHMAN

Terdapat banyak modul sebutan berada di pasaran yang memperkenalkan teknik pembelajaran dan pengajaran sebutan al-Quran al-Karim dan bahasa Arab. Ada yang menggunakan kaedah klasik, moden dan ada juga yang menggunakan kedua-dua kaedah secara komprehensif. Namun, amat sedikit kita lihat kaedah yang dapat memperbaiki sebutan dan menumpukan secara khusus teknik kepada pelajar bukan Arab. Sering kali diperkatakan tentang masalah sebutan pelajar Sabah tanpa membuat kajian secara terperinci dan ilmiah. Justeru, kajian ini dibuat untuk melihat masalah sebenar sebutan bunyi bahasa Arab pelajar Sabah dan seterusnya mengaplikasikan teori Mahjub (1993) untuk memperbaiki masalah sebutan bahasa Arab. Kajian ini dilakukan di sebuah sekolah menengah kebangsaan di Kota Kinabalu yang responden kajiannya ialah pelajar sekolah tingkatan empat. Objektif kajian adalah untuk mengenal pasti secara ilmiah permasalahan sebutan dalam kalangan pelajar Sabah dan mengaplikasi kaedah fonetik Mahjub, seterusnya melihat keberkesanan modul Mahjub sebagai instrumen terbaik memperbaiki sebutan pelajar Sabah. Kajian kualitatif ini menggunakan huruf-huruf konsonan yang sukar bagi pelajar asing yang dibuat oleh Mahjub (1993) yang menggunakan modul yang digunakan untuk memperbaiki sebutan Arab pelajar asing. Terdapat tiga langkah utama dalam kajian ini, iaitu rakaman ujian pertama (U1) sebagai sebutan bahasa Arab terkini pelajar Sabah, kemudian langkah kedua melaksanakan PdP berdasarkan PdP Mahjub dan langkah yang ketiga membuat rakaman ujian kedua (U2) untuk melihat keberhasilan teori Mahjub dalam memperbaiki sebutan pelajar Sabah. Hasil Kajian menunjukkan nilai yang sangat signifikan antara U1 dan U2. Daripada sembilan huruf yang diuji itu, konsonan ‘Ayn [ع] paling baik disebut oleh pelajar dan huruf Dad [ض] paling sukar disebut dalam U1. Dalam U2, huruf Ta’ [ط] paling sukar disebut dan huruf Sad [ص] paling mudah disebut. Dalam U1 Fathaṯ paling tinggi skor dengan 68.2 berbanding Sukun yang mempunyai skor paling rendah dengan 33.3. Secara puratanya, dalam U1 pelajar atau responden hanya mendapat purata sekitar 55 skor min bagi Dammaṯ dan Kasraṯ. Namun, pada U2 peningkatan masing-masing Dammaṯ dan Kasraṯ. mendapat skor yang hampir sama, iaitu 77.9 dan 76.9. Data menunjukkan bahawa Sukun paling bermasalah kepada responden dalam sebutan. Begitu juga terdapat perubahan yang signifikan dalam ujian kedudukan Fathaṯ, Dammaṯ dan Kasraṯ dari U1 kepada U2. Kajian menunjukkan bahawa teori Mahjub ini berhasil memperbaiki masalah sebutan dalam kalangan pelajar Sabah dan memberikan satu alternatif untuk diaplikasi dalam PdP pelajar dan membuka ruang kepada penulis lain untuk memanjangkan kajian pada masa akan datang. There are many modules/methods available in the market to introduce the techniques of learning and teaching the Holy Quran and the Arabic language. There are classical and modern methods in teaching the Holy Quran, and some might combine both classical and modern to help students to learn the Holy Quran. But there are only few methods which can really help to improve the pronunciation of Arabic especially among the non-Arab students who learn Arabic as a second language. This pronunciation problem is often discussed by the Arabic teachers but there are lack of proper studies to overcome this problem. Therefore, this study aims to identify specifically the pronunciation problem and to measure if the Maḥjub Theory can be applied to help in overcoming it. This study was conducted in a secondary school in Kota Kinabalu. The respondents were all Form 4 students. This qualitative study used the Maḥjub Module (1993) to rectify consonant letters that are difficult to pronounce by the Sabahan students. This study has undergone three phrases. The first phrase is U1 where the pre-test is carried out to evaluate the current capability of the respondents. The second phrase applied the Maḥjub Method in the PdP. The third phrase is U2 where the post-test was carried out after the Maḥjub Method was applied to the respondents. This study showed significant value between U1 and U2. Nine consonant letters were tested in this study. In U1, ‘Ayn [ع]was the easiest to pronounce and Dad [ض] was the most difficult to pronounce by the respondents. In U2, Ta’ [ط] was the hardest to pronounce and Sad [ص] was the easiet. In U1, Fathaṯ was the highest with 68.2 score as compared to Sukun with 33.3 score. Overall, respondents scored a mean of 55 for Dammaṯ and Kasraṯ in U1. However, in U2, Dammaṯ and Kasraṯ showed very close score as of 77.9 and 76.9. The data also showed that Sukun is the hardest part for the respondents.This study had proved that the Maḥjub Method is enabled to enhance and improve the difficulty in pronunciation among the students in Sabah. Therefore, the Mahjub Method gives educators an alternative approach to apply in their teaching and also other researchers for ideas to carry out future research in this field.


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