Effect of variable conduction angle on the losses of switched reluctance machine

Switched Reluctance Machine (SRM) is the advanced version of the stepper motor and since last decade, it is of high interest among researchers and industrial applications. Modelling an SRM relies on accurate data and proper selection of parameters. The next step is the performance analysis of the machine for which losses determination is indispensable. Previous studies have shown losses calculation only at a particular instant of switching of the machine (i.e., conduction angle). Therefore, the impact of losses in a motoring region cannot be justified. This paper investigates the impact of varying conduction angle on the performance of machines for a set of switch-on angle. Losses are calculated and predicted through simulating motor operating parameters carried out in MATLAB environment and accuracy of results are compared with experimental results

Transient modelling and simulation of a switched reluctance machine in different operating modes

An appropriate numerical computational method and simplest model captures the performance of Switched Reluctance Machines (SRMs). Several papers and computer software-based simulation models are reported in the literature. Each model has its own merits and demerits. This paper proposes a mathematical model, based on a combination of voltage and mechanical equations, suitable for the transient running of a switched reluctance machine. The simulation results of current, torque and speed profile of SRM are produced under current chopping control and voltage pulse width modulation control. The proposed work has used experimental data of flux linkage and static torque in the mathematical model for best performance and control of the machine. The obtained simulation results are verified with experimental results. This model can be extended to a range of rotor position where the machine can be switched at decreased and increased inductance region which gives motoring and generating operation mode

The Role of Radiology (X-Ray versus Computed Tomography) in Medicolegal Cases Presented at a Tertiary Care Hospital in Pakistan

Objectives:  A prospective observational study was aimed to assess the role of plain radiographs and computed tomography in detecting head injuries presented at the medicolegal office at the Forensics and Radiology Departments, Gambat Medical Hospital, Sindh. Material and Methods:  All cases referred from the Medicolegal Office (MLO) with head injury were included. All victims underwent X-ray head and computed tomography skull was done with 1 or 1.5 cm thick axial sections without administration of intravenous contrast. The radiological reports of X-ray head and CT scans were documented and comparatively evaluated. Results:  Mean age was 38.63 ± 3.91 years. In 51 (45.13%) cases, X-ray was able to detect skull fracture, while CT scan detected 64(56.64%) skull fractures. There were 54 (84.3%) true positives, 3 (2.6%) false positives, 10(8.8%) false negatives, and 40 (40.7%) true negatives. The accuracy of X-ray to detect skull fracture was 88.50%. Conclusion:  X-ray had a sensitivity and specificity of 84.38% and 93.88%, respectively. It is a reliable tool to detect skull fractures in victims of assault in comparison with CT scans. X-ray is also associated with low dose radiation exposure as compared with CT scan which delivers 70 times more exposure than the former

Hardware Implementation of Producing Variable Conduction Angles of a Switched Reluctance Motor

ABSTARCT INTRODUCTION For optimal operation of the motor, the necessity of selection of the appropriate switch-on and conduction angles is inevitable. The switch gate signals relative to the rotor position are applied at the gate-emitter terminal of the switching devices which are used in the converter of the motor. A conduction angle can be defined as the duration of the gate pulse for which the switching device remains in its' conduction state or 'ON' state. The literature review presented in this paper is mainly related with the basic control parameters of the drive system which are switch-on, switch-off and chopping current level

Medico-Legal Cases (MLC) Presented at a Tertiary Care Center and Acute Symptoms of Post-Traumatic Stress Disorder among the Survivors

Objectives:  An observational, prospective study was conducted to determine the incidence and risk factors associated with victims of physical assault and symptoms of post-traumatic stress disorder (PTSD). Material & Methods:  All the registered medico-legal cases reported to the emergency department of Gambat hospital were included in the study. The data was collected on a predefined questionnaire including age, gender, mode of injury, weapon of the injury, type of assault (blunt or penetrating), firearm injuries, and road traffic accidents from medico-legal registers. Impact of Event Scale (IES) was used to assess Post-traumatic stress disorder. Results:  The mean age (SD) of victims was 29.3 (10.25) years. Blunt injuries were experienced by 47 (31.33%) victims. The majority of the victims suffered road traffic collision injuries, 59 (39.33%). Forty-eight (32%) victims had substantially higher IES scores (above 37) that confirmed severe PTSD that may contribute to the suppression of the immune system’s functioning among survivors. The majority of the victims were between 18 and 40 years. Conclusion:  The most common cases were related to road traffic collisions followed by blunt injuries. The incidence rate of PTSD was also prevalent in these individuals. Thus, strategies should be developed to prevent such incidents and those who suffer from such traumatic events must be offered psychiatric consultation

Parameters extraction of photovoltaic cells using swarm intelligence based optimization technique: research on single diode model and double diode model

Solar-energy is a clean source of energy and photovoltaic (PV) panels are constructed from solar cells (SC) which convert energy of light into electricity without any environmental effect. The researchers and policy makers focus on the huge scale adoption of solar panels due to its cleaner production. However, there is non-linear behavior in current-voltage characteristics of solar panels and shortage of data in manufacturer’s datasheet. In order to enhance the efficiency of solar panels it is mandatory to develop the PV panels scheme accurately by extracting the basic parameters. In this research study a mathematical model of two different solar cell models is used such as Single Diode Model (SDM) and Double Diode Model (DDM). The Particle Swarm Optimization (PSO) is used to extract the five and seven unknown parameters of SDM and DDM. The algorithm runs with one thousand iterations to minimize the Root Mean Square Error (RMSE) where the RMSE is the vector of five unknown parameters for SDM and seven for DDM. The superiority of proposed PSO algorithm is proved by the optimized results of unrevealed parameters with minimized RMSE of up to 10-3. Optimum parameter values for the solar cell models are applied on the real time data of a 55 mm diameter commercial RTC-France SC. Finally, the results reveal that P-V and I-V curves exhibit smallest deviation between estimated and real time values. The results reveal that the proposed PSO converges to optimal solution with least number of iterations compared to the existing metaheuristic algorithms

Input data for mathematical modeling and numerical simulation of switched reluctance machines

The modeling and simulation of Switched Reluctance (SR) machine and drives is challenging for its dual pole salient structure and magnetic saturation. This paper presents the input data in form of experimentally obtained magnetization characteristics. This data was used for computer simulation based model of SR machine, “Selecting Best Interpolation Technique for Simulation Modeling of Switched Reluctance Machine” [1], “Modeling of Static Characteristics of Switched Reluctance Motor” [2]. This data is primary source of other data tables of co energy and static torque which are also among the required data essential for the simulation and can be derived from this data. The procedure and experimental setup for collection of the data is presented in detail

Introducing Dual Suspension System in Road Vehicles

The main objective of suspension system is to reduce the motions of the vehicle body with respect to road disturbances. The conventional suspension systems in road vehicles use passive elements such as springs and dampers to suppress the vibrations induced by the irregularities in the road. But these conventional suspension systems can suppress vibrations to a certain limit. This paper presents a novel idea to improve the ride quality of roads vehicles without compromising vehicle?s stability. The paper proposes the use of primary and secondary suspension to suppress the vibrations more effectively

Actuation Characteristics of 0.15mm Diameter Flexinol® and Biometal ® Wire Actuators for Robotic Applications

In this paper the actuation properties of two NiTi (Nickel Titanium) SMA (Shape Memory Alloy) actuators available under the commercial names of Flexinol ® and Biometal ® are investigated and compared with each other. Both actuators have diameter of 0.15mm and transformation temperature of 70 o C. The diameter of 0.15mm is selected because of best combination of force and cooling time. An experimental test rig specially designed and developed by the first author was used to conduct tests on the actuators. Both actuators were tested by supplying actuation voltages of 5 and 5.5V. Actuators were thermomechanically loaded for 100 cycles and their strains were recorded. The results of the tests show that 5.5V actuation resulted in greater strain. It was found from the test results that Biometal ® actuators produced more strain as compared to Flexinol ® actuators for both the actuation voltages. However, the drift results showed that higher strains in Biometal ® are due the permanent deformation of the same. This shows that Flexinol ® actuators possess better actuation characteristics as compared to Biometal ® actuators

Modeling of Static Characteristics of Switched Reluctance Motor

To investigate the running characteristics of a switched reluctance motor, the static characteristics and related input data tables are required. The static characteristics comprise of flux linkage, co-energy and static torque characteristics. The co-energy and static torque are calculated once data of magnetization characteristics is available. The data of co-energy is required for the calculation of static torque characteristics. The simulation model includes the data of static characteristics for prediction of the instantaneous and steady state performance of the motor. In this research a computer based procedure of experiments is carried out for measurement of the magnetization characteristics. For every set of measurements, the removal of eddy current is carefully addressed. The experiments are carried out on an existing 8/6 pole rotary switched reluctance motor. Additionally, the instantaneous phase current, instantaneous torque and flux waveforms are produced by using linear, which is by default and spline data interpolation separately. The information obtained from theses simulation results will help in an improved simulation model for predicting the performance of the machine