Recently induction motor control techniques have gained their importance in many industrial applications. To obtain fast dynamic torque & flux response Direct Torque Control (DTC) of Induction Motor is implemented using steady state & transient input conditions in MATLAB/Simulink. In order to control both torque and stator flux directly, they need to be predicted to limit them within hysteresis band closed to desired values. This can be realized by selecting suitable sector in space vector modulation. It can perceive that the torque is dependent on the stator flux, rotor flux and the angle between their vectors. In this paper, we have simulated and analysed torque and flux ripple factor for different conditions.

Analysis of Torque and Flux Ripple Factor for DTC and SVM - DTC of Induction Motor Drive

A Model Predictive -Direct Torque Control (MP-DTC) technique is proposed for Matrix Converter (MC)-based Permanent Magnet Synchronous Motor (PMSM) drive system, which reduces the torque ripples, does not need the duty cycle calculation, and ensures the fixed switching frequency. The predictive model of PMSM and MC is realized by means of State model. Then, the advanced MC-fed model predictive DTC algorithm is implemented based on cost function evaluation. The simulation results exhibit remarkable torque ripple reduction with the help of Model Predictive Control (MPC). As a result, the proposed strategy is proved to be effective in minimizing the torque ripples for MC-based PMSM drives.

Torque ripple minimization of Matrix Converter-fed PMSM drives using Model Predictive Torque Control

Background and objective: Neck pain is one of the most important factors for degenerative changes in cervical spine. Magnetic Resonance Imaging (MRI) is best imaging modality for evaluation of changes in cervical spine due to neck pain. The aim of this study is to determine the frequency of MRI findings in patients with neck pain. Material and methods: A convenient sample of 78 patients with neck pain was used in this descriptive cross-sectional investigation referred to radiology department of Gondal medical complex Gujranwala for evaluation of MRI findings of cervical spine in patients with neck pain during a time period of 4 months from January 24, 2022 to May 24, 2022. MRI was done using 1.5T scanner. Results: The patients belonged to the age group were between 13 to 80 years old, with a mean age ± SD of 44.83 ± 14.22 years. This study showed that female (53.8%) ratio was higher than male (46.2%). Total of 78 patients was suffering from neck pain only 10 were observed with radiating shoulder pain. There were no degenerative findings found in 16 patients. The most common radiological findings were disc osteophyte which account for 46 (59.0%) more prevalent at C5/C6 level. Conclusion: In this study, neck pain is commonly caused by degenerative changes in cervical spine and it is more common at C5/C6 level. MRI is best modality and it's a non-invasive approach for detecting degenerative diseases early and initiating treatment.

/pdf/frequency-of-mri-findings-in-patients-with-neck-pain-1az9lhrv.pdf

Frequency of MRI Findings in Patients with Neck Pain

Background: Cerebral aneurysm is the basic cause of sub-arachnoid hemorrhage; Computed tomographic angiogram is the non-invasive approach to diagnose aneurysm by reconstructing the image in 3D dimension making it possible to locate the aneurysm and differentiate it from other arteries. Objective: Focus of this study was to investigate the accuracy of CTA to detect the aneurysm, its type, location and size. Material and method: Data of 50 patients was taken retrospectively with cost-benefit approach that undergoes non-invasive CTA through Aquilion 64-slices CT machine under post-processing work station. Results: This retrospective study is taken with 50 patients, with a 38 percent positive predictive value and a 62 percent negative predictive value, multi-slice CT properly revealed substantial aneurysm in 19 of 50 cases. Conclusion: 64-slices CT provides high diagnostic accuracy for detecting the aneurysm in cerebral arteries with a non-invasive angiogram procedure.

/pdf/detection-of-cerebral-aneurysm-in-cerebral-arteries-1i7svy9t.pdf

Detection of Cerebral Aneurysm in Cerebral Arteries Following Non-Invasive CT Angiogram

An advanced direct torque control (DTC) technique using Model predictive control (MPC) is proposed for matrix converter (MC)-based permanent-magnet synchronous motor (PMSM) drive system, which reduces the torque ripples, does not need the duty cycle calculation, and ensures the fixed switching frequency. Analytical expressions of change rates of torque and flux of PMSM as a function of MC – dqo components are derived. The predictive model of PMSM and MC is realized by means of State model. Then, the advanced MC-fed DTC algorithm is implemented based on Cost function evaluation. The simulation results exhibit remarkable torque ripple reduction with the help of MPC. As a result, the proposed strategy is proved to be effective in minimizing the torque ripples for MC-based PMSM drives.

/pdf/torque-ripple-minimization-of-matrix-converter-fed-pmsm-59lyrwcqzi.pdf

Torque ripple minimization of matrix converter -fed pmsm drives using advanced direct torque control

In this paper Model based Predictive Control (MPC) is used for torque control of three phase Induction Motor. In conventional torque control methods, a switching table is used for switching of the inverter in order to keep the torque and flux within the limits. MPC can be used to reduce the switching frequency of the inverter along with better torque and flux response. Torque and flux is predicted for next few samples and most suitable sequence is selected which causes least inverter switching. Receding horizon policy is applied in which the first switching state of the selected sequence is applied to inverter. MPC requires complex computations which limits its application. Finally a Branch and Bound algorithm is applied in order to improve its computational cost.

Direct torque control (DTC) of three phase Induction Motor using Model based Predictive Control (MPC) scheme deploying Branch and Bound algorithm

Background: Urolithiasis refers to the formation of calculi as a result of a disruption in the equilibrium between salt solubility and precipitation in the urinary system. Computed tomography is considered to be extremely sensitive diagnostic test for its detection due to development in technology. The goal of this study was to find out the accuracy of ultrasound for detection of urinary tract stones as compared to CT KUB. Objective: The purpose of this study is to evaluate the sensitivity and specificity of ultrasound with the reference of CT KUB for the diagnosis of urinary tract stones. Material and Method: The cross-sectional study was conducted from January 13, 2022 to May 13, 2022 in the Department of Radiology, Gondal Medical Complex Gujranwala, in 78 patients who underwent simple CT KUB after USG with suspected urinary stones. Ultrasound and CT findings were compared based on age, gender, clinical appearance, number of stones, and location. All data was collected using a self-made questionnaire. I analyzed the data using SPSS version 26. USG specificity, sensitivity, positive predictive value, and negative predictive value were evaluated using CT as a reference standard. Results: Among the 78 patients, 56.4 % (n=44) were male and 43.6 % (n=34) were female. The average age of the patients was 41.5430 years. Urolithiasis was discovered in 80.76 % of the patients (n=63) who had CT KUB. Trans-abdominal ultrasound sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy in urolithiasis were calculated to be 68.3 %, 66.7 %, 89.6 %, 33.33 %, and 67.95 %, respectively. Conclusion: Trans-abdominal ultrasonography has a satisfactory diagnostic accuracy for urolithiasis since a range of parameters such as operator reliance, patient compliance, and stone size or location determines its sensitivity. When a CT scan is unavailable or contraindicated, it may be utilized as an alternative.

/pdf/diagnostic-accuracy-of-trans-abdominal-ultrasound-in-2hzjjlkq.pdf

Diagnostic Accuracy of Trans-Abdominal Ultrasound in Detection of Urinary Tract Calculi as Compared to CT KUB

Fetal growth retardation is described as infants whose weights are much less than expected. Population based norms are used to categorize abnormal growths. The objective of the study was to determine the frequency of intrauterine growth retardation on antenatal ultrasound scan. It was an observational descriptive study conducted at the Radiology Department of Fatima Memorial Hospital, Shadman Lahore. Patients visited the Ultrasound Department for Obstetric scan. The study was conducted in 6 months from January to June in 2022. The sample size of 87 was calculated for study with expected rate of 9% of pregnancies resulted in intrauterine growth retardation at 5% level of significance at 5% margin of error. The study included pregnant females in third trimesters of pregnancy. The data was analyzed using SPSS version 20. A total of 87 obstetric ultrasounds were performed during the study period. The mean age of the patients was 28.69 ±4.46 years with age range 20-42. The 87 included patients showed mean gestational age 35.29 ±2.50 weeks. The mean biparietal diameter was 8.69±0.57 cm and abdominal circumference was 29.72±3.03 cm. The mean fetal body weight is 2.52±0.59 kg. The frequency of intrauterine growth retardation was 10.3%. Fetal biometry, biophysical profile and Doppler studies were helpful in the diagnosis of intrauterine growth retardation and evaluation of ultrasound parameters in third trimester.

Prevalence of Intrauterine Growth Retardation on Antenatal Ultrasound Scan in Lahore, Pakistan

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