DC-link voltage balancing and control of qZ-source inverter fed induction motor drive

Poor performance of the motor drive system is caused when the direct current-link (DC-link) capacitor voltages of the inverter are not sufficiently generated. This is mainly because of the various load torque changes and input voltage fluctuation. The qZ-source inverter operates with a fully shoot-through technique. This technique causes mismatching between the upper and lower DC-link capacitor voltages. Without capacitor voltage-balancing function, the desired DC-link capacitor voltages could not be provided or maintained when there are load and speed changes. A Sawtooth carrier-based simple boost triple-sixty-degree (TSD) pulse width modulation (PWM) technique is used to drive the qZ-source T-type inverter because this technique can give a more significant boost DC-link voltage than a traditional simple boost PWM technique. Proportional integral (PI) controller is applied for the DC-link voltage controller to achieve the fast response and less steady-state error. The simulation model was constructed for a 4 kW, 400 V, 1,400 rpm induction motor (IM) drive system used in rolling mill using MATLAB/Simulink with and without voltage balancing function. As a result, DC-link voltages of the qZ-source T-type inverter fed the induction motor drive system could be controlled using a capacitor voltage-balancing function and the output power of the motor from the simulation result is approximately equal to 4 kW

Observational study of adult respiratory infections in primary care clinics in Myanmar: understanding the burden of melioidosis, tuberculosis and other infections not covered by empirical treatment regimes.

BACKGROUND: Lower respiratory infections constitute a major disease burden worldwide. Treatment is usually empiric and targeted towards typical bacterial pathogens. Understanding the prevalence of pathogens not covered by empirical treatment is important to improve diagnostic and treatment algorithms. METHODS: A prospective observational study in peri-urban communities of Yangon, Myanmar was conducted between July 2018 and April 2019. Sputum specimens of 299 adults presenting with fever and productive cough were tested for Mycobacterium tuberculosis (microscopy and GeneXpert MTB/RIF [Mycobacterium tuberculosis/resistance to rifampicin]) and Burkholderia pseudomallei (Active Melioidosis Detect Lateral Flow Assay and culture). Nasopharyngeal swabs underwent respiratory virus (influenza A, B, respiratory syncytial virus) polymerase chain reaction testing. RESULTS: Among 299 patients, 32% (95% confidence interval [CI] 26 to 37) were diagnosed with tuberculosis (TB), including 9 rifampicin-resistant cases. TB patients presented with a longer duration of fever (median 14 d) and productive cough (median 30 d) than non-TB patients (median fever duration 6 d, cough 7 d). One case of melioidosis pneumonia was detected by rapid test and confirmed by culture. Respiratory viruses were detected in 16% (95% CI 12 to 21) of patients. CONCLUSIONS: TB was very common in this population, suggesting that microscopy and GeneXpert MTB/RIF on all sputum samples should be routinely included in diagnostic algorithms for fever and cough. Melioidosis was uncommon in this population

Building detection from google map

In urban areas, buildings are often used as landmarks for localization. Reliable and efficient recognition of building is crucial for enabling this localization functionality. This FYP project represents a content-based image retrieval system for buildings images. In this context, the ultimate aim is to develop a simple building retrieval system that can be implemented in any imaging devices. The first stage of the building recognition is to detect the building using consistent-line clustering technique. Edges of the image are clustered according to the color and spatial features. Line segments from other non-building objects are eliminated in this stage and the final consistent-line cluster has been used to represent the main building. In the second stage, the color feature of the building are extracted using the consistent-line cluster obtained in first stage. The color indexing vector has been constructed using the colors from left and right region of each line segment. Finally, for effective image retrieval, a simple matching function is defined based on the Chi-square of measure of similarity between the indexing vectors from query image and database images. The performance of the retrieval system is evaluated using an image database of 30 buildings taken from the publicly available database, ZuBuD, and 150 query images have been used to test the system.Bachelor of Engineerin

Endless Possibilities Await

Naing Lin Tun was awarded Honorable Mention for his essay. At the request of the author, this essay is not available for download

Double Loop Control of H-Bridge DC Chopper Fed Permanent Magnet DC Motor Drives Using Low Cost Hardware

This paper presents the two loop proportional integral (PI) controller for speed control of permanent magnet DC motor (PMDC) motor drive with H-bridge DC chopper. PMDC motors are widely used in many applications because of having a good performance and it is easy to apply the speed control. The speed can be adjusted by using armature voltage control as it had only the armature circuit. H-bridge DC chopper circuit is used to obtain the desired speed in any direction. In this system, the two loop PI controller is designed by using pole-zero cancellation method. The speed and current controller gains are considered depending on the sampling frequency of the microcontroller. An Arduino IO package is used to implement the control algorithm. Both simulation and experimental results are presented to prove the correctness of the mathematical model

Population Density of Rice Root Nematode, Hirschmanniella oryzae (Luc and Goodey, 1964) in Nay Pyi Taw Union Territory

Soil and root samples from 44 rice fields were collected on 5 summer rice varieties (Manawthukha, Sinthukha, Shwethweyin, Palethwe and Yet-90) in 5 townships (Lewe, Tatkon, Pyinmana, Zabuthiri and Dekkhinathiri) to determine the population density of Hirschmanniella oryzae. It was observed that 98.89 % out of 44 fields sampled were infested with the rice root nematode, H. oryzae. Based on the prominence value (a combination of the frequency of occurrence and abundance) of H. oryzae, Tatkon Township was the most infested region and the lowest population was found in Lewe Township. The highest population of H. oryzae from soil and root was observed in Sinthukha and the lowest population was found in Shwethweyin. All summer rice varieties surveyed were observed to be either susceptible or highly susceptible to H. oryzae. In two different cropping sequences, rice-blackgram-rice cropping sequence had the lower nematode population than that of rice-rice cropping one. Moreover, the lower nematode population was also found in direct seeding than in transplanting method

Tectonic, diapiric and sedimentary chaotic rocks of the Rakhine coast, western Myanmar

The western margin of Myanmar is the northern extension the active Sunda (India-Eurasia) subduction zone. Coastal regions and offshore islands have remarkable exposures of chaotic rock terranes along wave-cut terraces that allow characteristics of tectonic, sedimentary and diapiric mélanges to be recognized. Tectonic shear zones (tectonic mélanges) contain fragments of Cretaceous ophiolites (chrome-spinel-bearing peridotites and radiolarian cherts) that are in contact with thrust packets of Eocene turbidite units (broken formations). The turbidites contain shale-rich beds that have been sheared during soft-sediment deformation (sedimentary broken formations) and are sandwiched between undeformed thick sandy beds. These are mass transport deposits (MTDs) that most likely formed during deposition of the initial detritus of the Himalayan orogenic zone, probably trench slope basins on the accretionary prism. The ophiolitic and turbiditic thrust slices have been exhumed and are currently being intruded by active mud volcanoes that bring fragments of units up from depth to the surface, forming diapiric mélanges. These diapiric mélange bodies contain only small fragments (<50 cm) that are randomly oriented and do not exhibit shear fabrics. Because the region lacks superimposed deformation characteristic of most orogenic belts, the origins of all three rock bodies can easily be distinguished.Partially funded by US National Science Foundation Grant #OCE-1260718. SOEST contribution # 10634