The present article proposes the realization and implementation of an algorithm for the selective extraction of a spectral component using fast FFT analysis, from the mechanical vibrations recorded with the help of a broadband acoustic sensor. The hardware device consists of a high-resolution data acquisition system and the storage of samples of the useful signal in a memory area. The selective processing of vibrations is done with the help of a FFT algorithm implemented with the help of the ATMEGA microcontroller based on the binary calculation made by weighted amounts with coefficients from the frequency band used. After obtaining the band spectrum of the signal, a software mask will be applied, with a frequency window that will be pre-set by the human user, and only the amplitude of the signal with the desired spectral component will be displayed, thus achieving an intelligent vibration tracking produced by a certain mechanical element or selected functional assembly. The vibration spectrum of a mechanical machine is composed of the sum of the individual spectral components of all interdependent mechanisms. Simulation performed for this paper and results processed using the proposed method lead to the conclusion that a unique harmonic spectrum, obtained using the Fourier transform algorithm with fixed frequency window and limited number of spectral markers, correspond in a unique way to a mechanical state of wear that the microcontroller can store using a variable magnitude vector. Obtaining a buffer of spectral markers stored together with information about the speed and engine rpm allow the development of an original method of fault detection. The article proposes the implementation of the software method with a hard architecture that includes, low pass filter, information processing and display units.
As per the first prototype developed (ultrasonic glove for visual impaired users [1]) a follow-up discussion with a teacher and several students of the Special School for the Visually Impaired in Cluj-Napoca regarding how other other devices may help the life of a visual impaired person. They underlined out the difficulty of matching colours on clothes. This is the reason for this research for available solutions for a colour detecting sensor that can work on the same platform and fulfils the same principals: cost-effective, easy-to-use, portable and low-battery consumption. TCS230 was the best fit for this purpose, an optical colour sensor. Based on the values the sensor reads for red, green and blue, the software decides what colour is displayed in front of the sensor. The prototype that was build can read to the user 11 colours. In order to add more colours in the near future s and also to be able to maintain the prototype effectively, it was decided to use a development board, not to build a smaller scale of it using only the microchip and other components needed.
There is a trend toward increasing the reliability of the power electronics converters used in many applications. Parameters like reliability, efficiency, and power density often are quite opposable, so it is hard to get them all toghether. In this paper, investigation of the load resistor impact upon the overall reliability of a simple DC-DC PoL (Point-of-Load) converter is assessed. SA-TB130PCB-000 evaluation board having embedded synchronous buck converter was selected for testing and measuring MTBF for such a converter. Thermal scanning in infrared was performed in order to obtain the component capsule's temperature which is needed in stress factor calculation. Calculation follows the data provided by MIL-HDBK-217F rev.2 well known and accepted reliability standard.
As an environmentally compatible device, combining low costs, transparency of the entire Photosynthetic Active Radiation (PAR) domain, and an optimal efficiency of the solar cell for the elimination of any energy provided by the conventional sources, dye-sensitized solar cells (DSSCs) are proposed as the most promising candidates for a wavelength-selective photovoltaic greenhouse. Here, we report the influence of temperature and a small concentration of water in the organic electrolyte on the photocurrent density–photovoltage (J–V) characteristics of UV dye-sensitized solar cells. Our results have highlighted that using a special architecture of the photoanode, up to 60 °C, no degradation effect of 10 % water on the photovoltaic performance of DSSC was observed. On the contrary, a small concentration of water has a beneficial effect on the thermal stability of the DSSC confirming the attractive premises for future implementation of DSSCs in the roof of the greenhouse and the long-term stability in outdoor conditions.
This paper presents a successful attempt to create an innovative way of monitoring the air particles in a room. The sensor relies on two basic physics principles: the Tyndall effect and the Venturi effect. The work done so far consists in designing and modelling, 3D printing and testing the aforementioned method. The model proved to be feasible for both quantitative and qualitative air particle measurements, not knowing only how polluted a mass of air is, but also the nature of the pollutant.
An essential issue in power electronics field is the limitation of power losses in the power supply grid. The distortions created by each consumer add up in the main network. The effect seen by customer is distorted mains voltage. The effects observed by the electric energy distribution operator consist in the increase of losses in the network (at the same active power, the supply current of the harmonic polluting consumer is higher than the supply current of the resistive consumer). For an efficient operation, the circuits used to compensate the over polluted grids need ideal reference signals. Starting from the idea of identifying a viable solution to this problem, this paper proposes a designing method and testing of a quadrature oscillator (QVCO) to provide the compensation circuit with the ideal necessary signal. The proposed circuit was designed and tested. The experimental results obtained during the QVCO testing show that the designed QVCO circuit provides a perfect reference sinusoidal signal, synchronous with the fundamental voltage of power supply network/grid.
The paper describes an approach used in the learning process in the Digital Signal Processing course, which supports the development of scientific and ICT literacy skills when studying the topic “Design and Research of Digital Comb Filters Using MATLAB” at the University of Ruse. First, students consider the theory and applications of digital comb filters in the field of telecommunications. Then, students study the responses of the comb filters using MATLAB and Signal Processing Toolbox. In the end, students investigate the main applications of comb filters in the telecommunication area. All these research tasks help develop the scientific and ICT literacy skills of the students, one of the leading 21st-century skills.
A portable electronic system is an embedded electronic device that helps the consumer track a wide range of personal biometric data, ambiental data for monitoring the environment, or their fitness activity. The main benefit of data collection is that it can define your current health state and identify, treat, and manage potential medical issues that may arise. For this reason, in this paper, a portable embedded device was designed for monitoring a person's activities and environmental parameters. It was therefore necessary to create two PCBs, one for the portable device and the other for the receiver. Using the two PCBs, we successfully broadcast data up to 600 meters around the city. This distance exceeds the typical range attained using Bluetooth or Wi-Fi connected devices.
Environmental research has become a problem for today's society due to its implication in ensuring a healthier and more sustainable future. It anticipates and combats events that could change the health of the average person and the climate in which he lives. Air pollution is one of the main factors in premature deaths, posing a considerable risk to public health. The main diseases that can occur as a result of pollution are strokes or myocardial infarction. For this reason, citizens seek to be informed and know, in real time, the level of air quality both at the time when the information is sought and in the future. The air quality in that area can be predicted according to the variation of temperatures and air currents. This paper proposes the creation of a model to predict the level of air quality. Thus, the prediction will be made over a period of time in order to be able to adopt various specific measures that are required. For example, warning vulnerable people, the elderly, and parents with children, while limiting travel to certain areas for which air quality is exceeded.
This paper presents a wireless measuring and data acquisition system for a hydro-generator's stator and rotor which are part of the subsystem for monitoring, analysis, and diagnosis of the hydropower unit (hydraulic turbine and hydro-generator) for the production of electricity from hydroelectric power plants [1]. The system aims to measure the air gap, the magnetic field and the rotor pole temperature. The advantage over other existing devices is the immunity to EMI (Electro-Magnetic Interferences) of the air gap readings and the fact that there is no fixed power supply, no battery, but a supercapacitor for energy storage. The reading / transmission of information from the sensors is done multiplexed in order to rationalize the power consumption.
Nowadays the high-speed communication systems involve also high data rates with minimum error numbers. Differential transmission lines are a good solution to mitigate the different types of noise which inevitably occur and affect the signal. However, this comes with a disadvantage: the signal skew. The meander lines are used in Printed Circuit Board (PCB) to compensate the aforementioned problem. In addition, this method improves the signal integrity, and it is a popular choice for signals synchronization. In this paper, a study of the routing performances for a high-speed circuit at high frequencies is presented. The goal is to determine the optimum meander shape and the maximum speed at which the circuit operates. The performance evaluation was done in terms of S- parameters and the reflections level simulated with Time-Domain-Reflectometry (TDR) function. For simulations, a PCB with 2circuits of Ethernet type signals is considered. The signals are propagated through different PCB layers, from a line-separation relay to an integrated circuit. A series of bits was transmitted from the relay through the equivalent filter of the lines to the integrated circuit. The results showed a slight signal attenuation due to the mismatch of the impedance.
This paper presents the implementation of a system capable of monitoring the air quality from outside and inside the vehicle in which it is installed, displaying the information to the user through two screens and alerting him in case the level of air pollution is high. Also, the presented system records the latitude and longitude coordinates at which the measurements of the air quality parameters are made in order to display on a map the degree of air pollution in different areas travelled by the user. The data collected by the system are mainly related to the emissions released by motor vehicles that use thermal engines, however, common data such as carbon dioxide (CO2), temperature, humidity and atmospheric pressure are also monitored. The collected parameters related to the emissions released by vehicles are dust particles in the air (PM1.0, PM2.5, PM10), carbon monoxide (CO), total volatile compounds in the air (tVOC) and methane (CH4). Thus, the system can bring additional information both to the driver who is alerted immediately about the level of air pollution, and to society, which will have an overview of the air quality, on the widest possible area of road infrastructure, displayed on a map easy to access and understand.
The problem of today's congested traffic in big cities is an ever-increasing one because the number of vehicles participating in traffic is constantly growing. Congested traffic means much more time spent in the car, on the road, higher fuel consumption, as well as a source of stress and frustration due to lost time. Another consequence of traffic jam is represented by the increased level of pollution that affects the entire planet. In spite of all the recent road improvements, the construction of new highways and new connections, the problem of congested traffic still persists, especially in the big cities. That's why different urban traffic control systems have been created and implemented over time, since the 1970s, to help decongest it and spend as little time as possible in the vehicle. These urban traffic control systems are based on recording various data related to traffic, analyzing them and acting on the basis of the data to adjust traffic light times; traffic lights are an essential element for urban traffic, they can be controlled in real time to improve road traffic. In this paper, the main urban traffic control systems (Traffic Network Study Tool – TRANSYT, Split Cycle Offset Optimization Technique - SCOOT, Sydney Coordinated Adaptive Traffic System - SCATS, Urban Traffic Optimization by Integrated Automation - UTOPIA) will be analyzed and compared, respectively a case and statistics related to the congested traffic in the city of Bucharest will be presented.
In this paper is presented the design and the implementation of a benchmark system that is intended to be used in industrial applications where is necessary to analyze, test and validate the correct operation of low-power AC motors. The core element of the proposed system is represented by the USB-6000 multifunctional data acquisition module that is connected to a PC running a dedicated software application written in Lab VIEW. The relevant electrical and mechanical parameters of the tested AC motor are measured using a set of sensors for speed, voltage, current and vibrations. The initial conditioning and galvanic insulation of the signals acquired from sensors are realized with a separate digital input/digital output module. Although, in the proposed implementation, the benchmark system is specialized only on low-power AC motors, it can be easily adapted to operate with other types of electrical motors. By integrating the capabilities offered by the virtual instrumentation tools, corelated with the performances of the compact USB-6000 data acquisition module, a highly efficient, reliable and low-cost implementation of an AC motors testing system has resulted.
This paper studies the behaviour of Dye-sensitized solar cell in a roof tile application under partial shading conditions in comparison with silicon photovoltaic roof tile. The standard parameters of a photovoltaic solar cell are measured at standard test condition, defined as one Sun irradiance, 1kW/m2 with an Air Mass of 1.5 spectra and 25 °C ambient temperature. The above-mentioned test condition is useful for a comparison between the same generation of products but does not offer any information for on the field behaviour.
Fast response electromagnets are required for actuators in many mechatronics applications. Such actuators are on-off valves for digital hydraulics, new field in fluid power where fluid flow is controlled by a number of fast on-off valves connected in a structure similar with switches from an electronic digital to analogue converter. These valves must be very fast, with response times in millisecond range, and this requirement can be fulfilled if both mechanical structure and electronics are very fast. Our research focuses on the electronic driver and how to improve its speed without increasing supply voltage by adding a charged capacitor during off-on switching. Proposed method is simulated using LTspice program and implemented and tested on real circuits with a standard contactor as electromagnet load and with a real on-off valve for digital hydraulics.
In this paper, two dual hybrid couplers using artificial transmission lines are designed and analyzed. The artificial transmission lines are implemented in microstrip technology and using lumped elements to obtain the left-handed behavior. A detailed analysis of the real-life implementation of the couplers considering both the effects of microstrip lines and lumped elements is described, comparing the results of the two proposed couplers. The influence of the standardized values of the lumped elements and their finite quality factor is investigated when implementing the two dual hybrid couplers. Also, the phase difference introduced by the access microstrip transmission lines is investigated and ways of compensating it are discussed in correlation to the overall frequency response of the couplers.
Nowadays, more and more emphasis is placed on non-polluting electrical charge devices that increasingly satisfy the needs of the application. For this reason, a good part of the research focuses on the use of supercapacitors as devices for storing the electric charge and at the same time generating this charge to the system that needs a power supply. The capabilities of supercapacitors can significantly contribute to the proper functioning of the system where they are embedded and can also prolong its life given the fact that they have a very large number of charge-discharge cycles (> 100,000). Like any relatively new component, which is constantly being tested, it has also some disadvantages that the researchers in this area have tried to reduce. The materials used in the realization of supercapacitors represent the main source of influence on their operation. For example, the maximum working voltage (nominal voltage) is determined by the electrolytic decomposition voltage of the electrolyte solution. Talking about this, the paper's aim was to make and test new coin cells of supercapacitors in order to increase the maximum working voltage and capacitance per cell. We propose to use new materials that seem to bring benefits from this point of view to obtain supercapacitors that work at higher working voltages (over 3V). Thus, after testing and interpreting the obtained data, we can conclude whether the materials have been chosen according, in combination between electrode material and electrolyte solution proved to be suitable in finding a solution to this disadvantage of supercapacitors.
An innovative method for manufacturing solderless assembly for electronics eliminates the need for the laminated printed circuit board, but uses new materials in an additive manner to obtain fully encapsulated electronic modules. To characterize the reliability of such a module, data for material properties are needed, some of which (Poisson's ratio, Young's module) are not found in the datasheets. They are necessary for calculating the natural resonance frequency of plates made by these materials. The paper presents the determination of the parameters using the Digital Image Correlation method. Two epoxy system materials were studied: Epoxylite 235SG, and MC62/W363. The determined Poisson's ratio values (0.37, respectively 0.32) fall within the general range confirmed by other measurements for this type of material. For Young's module only one reference was found, for Epoxylite 235SG: the determined value (2624.40 MPa) is close to that resulting from the graph of its variation with temperature at 298.15K (2500 MPa), this value being obtained by a Dynamic-Mechanical Analysis method carried out by the Elantas' Research & Development Laboratory from Parma.
The paper presents the use of the experiential learning approach for teaching the topic “Implementation of Brent-Kung Adders Using Computer-Based Training”. Brent-Kung adders are implemented with various software tools, e.g. MS Excel, Logisim, and ISE Project Navigator, for simulating the process of adding two binary numbers. Based on the flipped classroom strategy, students investigate the theoretical issues concerning Brent-Kung adders, then they implement these adders with various computer-aided tools and in the end, they test the FPGA-based implementation of Brent-Kung adders with a lab board created at our University. The applications will be used in the educational process in the courses “Digital Electronics” and “Pulse and Digital Devices” at the University of Ruse, with the aim of easy adoption of the material studied by the students.
