Category Archives: Fără categorie

Ways to Determine the Structural Resource of Highly Maneuverable Aircraft

21 January 2022Fără categoriecburada

Abstract

This paper emphasizes the importance of monitoring aircraft structural fatigue and proposes as paramount the analysis of military aircraft structural constitutive materials aging process, during flight. Aircraft structural health monitoring is defined as an evaluation process for the integrity of key structural components with the sole purpose of enhancing flight safety and mitigating maintenance risks and loses. Nowadays, aircraft are predominantly built from composite materials with at least two layers with different mechanical properties, which combined, result in a new composite material with highly superior resilience and elastic properties. Even though there are great advantages of using composite materials, when it comes to operating military aircraft, a mere visual inspection cannot be sufficient for observing or identifying structural damages within the composite layers of the aircraft. The focus of this study is on improving the process of monitoring the structural condition of highly maneuverable military jet aircraft by using the strain gauge marks methods. Monitoring aircraft structural condition can be easily implemented, both during maintenance and flight missions, by using a wide array of sensors that can generate specific sets of instructions for all processes involved in enhancing flight and maintenance safety. The main concern of implementing a structural evaluation, within aircraft maintenance processes, sits on preventing and not ameliorating incidents and accidents during flight. As a result of the continuous research and testing, it has been proved that the operational resource of the aircraft structure, provided by the manufacturer, can be easily reached in a lot lesser flight hours than initially anticipated, by engaging the aircraft in specific operational missions and, therefore, inflicting pronounced fatigue on the aircraft structure.

Simulation of Multi-Motor Propulsion System for Energy Efficiency in Electric Vehicles

21 January 2022Fără categoriecburada

Abstract

For a vehicle, the knowledge of components, characteristics, performances, and behaviors are some base elements for a successful simulation. Today’s tools are offering instruments able to cover a such request and new possibilities appear. Choosing the right ones, representing the entire vehicle as a system of subsystems, integrating as much as possible the parameters of different components, are also few additional elements. For internal combustion engine vehicles, the generation and the transmission of the mechanical power to the wheels imply the usage of specific mechanic parts. From a single engine, the mechanical power is controlled to offer the requested torque and speed simultaneously to the vehicle wheels, passing by clutches and gearboxes. An electric propulsion, generating high torque at zero speed, and covering large speed area, implies less components for the mechanical transmissions. One single gear, a reducer, could cover the entire speed area request of the vehicle. On the other hand, it is possible to approach the generation of the mechanical power to the wheels, by using not only one electric motor, but one for each axle, or, even more, one electric motor for each wheel of the vehicle. This paper presents the usage of numerical simulation in such situations, emphasizing opportunities for onboard energy efficiency improvement, and opening new possibilities for optimization in multiple motor solutions.

Experimental Study of HBC Fuses with Aluminium Fuse Element at Minimum Rated Breaking Current, Maximum Rated Breaking Current and Transfer Current of Fuse-Switch Combination

21 January 2022Fără categoriecburada

Abstract

The article presents an experimental study of high breaking capacity fuses with aluminum fusible element with and without a eutectic point, at minimum rated breaking current, preceded by experiments at maximum rated break-ing current. The paper shows that in the construction with aluminum fusible element, the fuse has no problem breaking the maximum rated breaking current, but real difficulties appears when it comes to the minimum rated breaking cur-rent. The experiments were made on a homogeneous series 6-20 A, with a focus on the 36 kV, 25 kA, 16 A fuse. The fuses suffered multiple construction changes and tests with and without a eutectic point. After several tests was found an acceptable constructive solution was, but the obtained value for the minimum rated breaking current is not a commercially attractive value. It was also tested the capacity of the fuse to transfer the breaking duty to a load break switch.

Considerations on the Disturbances Occurred in the Operation of Medium Voltage Electrical Networks with Neutral Treated by Suppression Coil

21 January 2022Fără categoriecburada

Abstract

In this paper are analyzed the analytical models of theoretical calculation and analysis of the main conse-quences of neutral treatment by suppression coil on the ope-ration of medium voltage electrical networks, both in nor-mal regime and especially in single-phase fault regime. The size of stationary and transient overvoltages and fault cu-rrents is evaluated for a concrete case study. Also the au-thors present in this paper the results they obtained after the extension of their research and in the field of harmonic regime produced by the grounding of a power line. This type of fault occurs frequently in the case of medium voltage networks, with neutral treated with suppression coil. Thus, they managed to reconstruct the waveforms of currents and voltages during the fault period (grounding). Then, having these calculation elements available, a comparative analysis of similar incidents (earthing) from a 20 kV network with the neutral treated with classic suppression coil and mo-dern Trench suppression coil, respectively, was made.

Automatic Ventilation and Air Conditioning System for Educational Trainin

21 January 2022Fără categoriecburada

Abstract

The air quality from closed spaces is very im-portant for people or for technological processes. The heat-ing, ventilation and air conditioning installations ensure the maintenance of the air parameters in the rooms served with-in pre-established limits, throughout the year, regardless of the variation of meteorological factors, the degree of occu-pancy of the rooms or the development of production pro-cesses. The paper presents an automatic ventilation, heating and air conditioning system made on a small scale. Climatic parameters can be monitored and controlled in two ways: in local mode and also in remote mode. In local mode, the con-trol of the installation is done with a Mega 2560 develop-ment system made around the Atmega 2560 microcontrol-ler, which processes the information received from the DHT22 temperature and humidity sensor. Information about parameters and system status is displayed on the local screen. The WeMos D1 R2 WiFi development system based on an ESP8266 wireless microcontroller with Wi-Fi 802.11 compatible with the IDE-Arduino development environment was used for the remote control. All information is transmit-ted wirelessly to an online platform, called Cayene that al-lows their storage and control. The platform referred to offers a number of graphical features that do not involve costs for users. The system can be used both for educational purposes for engineering students, but can be adapted for real practical applications.

Comparative Analysis of Two Methods of Calculating the Prescribed Current in a Shunt Active Filtering System

21 January 2022Fără categoriecburada

Abstract

In this paper, the performance of a three-phase shunt active power filter (APF) using the instantaneous power theory (p-q theory) has been compared with that corresponding to the use of the synchronous reference frame (SRF) based method. It is clear that, under balanced and sinusoidal voltage conditions, these two methods gives similar results. The entire system has been modeled using MATLAB-SIMULINK software. The simulation results demonstrate the applicability of both methods for the APF control.

Optimization of Electromagnetic Devices using a RSM Enhanced ACOR Algorithm

21 January 2022Fără categoriecburada

Abstract

The present paper proposes and studies the effi-ciency of using a RSM enhanced ACOR algorithm for the optimization of electromagnetic devices. Different RSM methods, such as Box-Behnken, CCD and Doelhert, are applied to find most suitable parameters (optimal set) for the ACOR in order to solve the corresponding electromag-netic optimization problems. The parameters optimal set is found by building a metaheuristic function. In the same time, the optimal parameter set is searched and determined for each electromagnetic problems for different objective functions, the best and the average global best solution for a tests set. The electromagnetic devices to be optimized are the Loney’s solenoid and an energy storage device, as defined by the TEAM22 problem. Both electromagnetic problems are proposed benchmarks from electromagnetic community.

The Choice of the Main Power Components in Electric Traction Converters

21 January 2022Fără categoriecburada

Abstract

The choice of the power components of the electric traction converters for autonomous vehicles is a very important aspect in their design. The attention in this paper is first focused on the choice of the DC link capacitor, followed by choice of the IGBT modules, their testing and cooling. Then, the choice of power cables is approached. A dedicated test bench for electric traction converters for autonomous vehicles was designed and achieved. In defining the parameters of the test bench, various possible applications on battery-powered vehicles were taken into account, but also their performances, technical characteristics and functional characteristics. An important share belongs to the integrated propulsion/charging system of the Li-Ion battery developed by the company SC INDA SRL. It is already used in automotive on full-electric trucks and in the battery-powered electric locomotives.

Real-Time Sensorless Control of the PMSM based on Genetic Algorithm, Sliding Mode Observer, and SCADA Integration

21 January 2022Fără categoriecburada

Abstract

This paper presents an application for real-time implementation of the Permanent Magnet Synchronous Motor (PMSM) sensorless control system and its integration into Supervisory Control And Data Acquisition (SCADA). Starting from the operating equations of the PMSM and by implementing the global Field Oriented Control (FOC) con-trol strategy, in which the saturation of the integral compo-nent of the PI controller is prevented by using an anti-windup technique, the numerical simulations performed in Matlab/Simulink lead to good performance, which recom-mends the real-time implementation. For the optimal tuning of the PI speed controller of the PMSM the genetic algo-rithm (GA) is used. Numerical simulations are performed in order to choose the type of Digital Signal Processing (DSP) used for the real-time implementation, considering that a global criterion of successful implementation is the perfor-mance/cost ratio. Besides, the integration into SCADA pro-vides flexibility of the control system but also the possibility of online/offline processing from the point of view of other specific requirements. Among them we mention the energy quality analysis, whose first exponent calculated also in real-time is Total Harmonic Distortion (THD). Real-time imple-mentations are performed in Matlab/Simulink and Lab-VIEW programming environments. According to the trend of the last years, the use of an Internet of Things (IoT) plat-form for viewing the variables of the control process on the Internet plays an important role.

Impact of Experimental Measurements Accuracy on Validation Process of Crimped Connections

21 January 2022Fără categoriecburada

Abstract

In the process of validation of crimped connec-tions, the determination of the connector resistance factor and of the initial scatter coefficient has a decisive role. In this paper is studied the impact of the experimental meas-urements accuracy on the calculation of initial scatter, cu-mulating data from various types of crimped connections. This coefficient provides information on the behavior of the crimped connection immediately after installation before any aging effect begins. The standards establish that 6 sam-ples are sufficient to be tested to estimate the identification of a “family” of connectors. The measurements were per-formed on crimped connections of barrel of terminal lug type for three cross sections of cables and on crimped con-nections of bimetallic through connector type for two pairs of cross sections. The initial scatter is influenced by 6 repre-sentative measured quantities as voltage drops, currents and conductor lengths. First, it was imposed a variation by one unit of hundredths digit of initial scatter and was recorded the variation of each quantity, the others 5 quantities being kept constant. Then simultaneous variations of the 6 quanti-ties caused by device reading errors were imposed, deter-mining the quantities with the greatest influence on initial scatter. Useful recommendations for experimenter are made.