Dejan Mitic

CONTROL SYSTEM OF STEEL BATTERY CHARGER

A practical realization of control of a diode–thyristor bridge is provided in this paper. The proposed control logic is applied to an NiCd accumulator charger. These accumulators are used for power supply of electrical devices and equipment in CFR locomotives. The control system provides a regular mode of NiCd accumulators charging and discharging, and, in this way, their long lifespan. A hardware configuration and a control algorithm for efficient NiCd accumulator charging and preventing overcharging and overheating are provided.

Unruptured tubal pregnancy in early second trimester

Introduction Most ectopic pregnancies are tubal pregnancies. They are potentially life-threatening conditions with a high mortality rate if unrecognized. The diagnosis is established when the first warning symptoms occur, or during the first prenatal visits to a gynecologist. The diagnosis in the second trimester is extremely rare, since clinical presentation resulting either from the expulsion of the fetus into the peritoneal cavity or from the tubal rupture is manifested by that time. If there is no rupture or the expulsion of the fetus, the pregnancy is allowed to continue and ectopic pregnancy diagnosis may be established in the second trimester. Case outline We present a case of a 31-year-old second gravida with a vital intrauterine pregnancy confirmed at the first examination. In the early second trimester, the patient visited her doctor due to vaginal bleeding. After a gynecological examination and ultrasonography, ectopic pregnancy was suspected, so the patient underwent laparotomy. Ectopic pregnancy was confirmed and adnexectomy was performed. Conclusion Early ultrasound examinations have to confirm whether eutopic pregnancy is present. A misdiagnosis and monitoring of ectopic pregnancy as eutopic one is potentially life-threatening for a pregnant woman.

Experimental Verification of EOG Signal Measurement Using the Modified Digital Stochastic Measurement Method

Experimental verification of the simulation model for modified digital stochastic measurement (MDSM) of biomedical signals in the time domain, is presented in this paper. This method is based on well-known digital stochastic measurement method (DSMM) with low-resolution analog-to-digital converters (ADCs) and accumulation. An electrooculography (EOG) signal is used as an example of a real low nonstationary biomedical signal. Realized experimental model is based on a personal computer (PC) with additional microcontroller hardware for analogue signal processing. The experimental printed circuit board (PCB) has been designed with microcontroller (MCU) STM32F303C6T6. The experimental results are compared with the results of simulations, and the comparison confirms the simulation. Considering obtained results, the suggested model can be used for design and realization of an instrument with sufficient accuracy, benefiting from the hardware simplicity of the method.

Digital stochastic measurement of noised biomedical signals: Simulation versus experiment

An experimental hardware solution, which has been realized in order to verify the simulation model for digital stochastic measurement (DSM) of biomedical signals, is presented in this paper. The simulation has been realised using the Matlab program, and electrooculography (EOG) signal is used as an example of a real low nonstationary biomedical signal. Realized experimental hardware solution is based on a personal computer (PC) with additional microcontroller hardware for analogue signal processing. The experimental printed circuit board (PCB) has been designed with microcontroller (MCU) STM32F303C6T6. Tests are done with adding a noise-varying signal-to-noise ratio (SNR) from 10 to -10 dB. The experimental results are compared versus results of simulations, and the comparison confirms the simulation.

Modeling of imperfect system based on almost orthogonal polynomials

A new class of the almost orthogonal filters is defined in this paper. These filters are a generalization of the classical orthogonal filters commonly used in the circuit theory, control system theory, signal processing, and process identification. Almost orthogonal filters generate the series of almost orthogonal Legendre functions on the interval (0, ¿). Its a well known fact that every real system is imperfect, so the models of these systems should be imperfect, also. A new method for obtaining an imperfect system model by using almost orthogonal filters based on almost orthogonal functions is proposed. Simulations are performed to approve theoretical results and demonstrate that the method described in the paper is suitable for modelling of imperfect systems.

On the class of nonlinear oscillators with several steady states

In this paper a class of continual nonlinear oscillators has been presented, with respect to initial condition, achieve numerous different amplitudes, i.e. with several steady states. Mentioned oscillators are able to generate oscillations with exactly defined amplitudes and frequency. Oscillator generates periodical oscillation and it is invariant to external disturbances.

Test device for motor vehicle breaking system

A method of measurement and data acquisition for motor vehicle breaking system test device is shown in this paper. With respect to automation of measurement process and reports generating the test device is designed. The device is based on industrial PC and embedded microcontrollers, and developed according to object-oriented design and programming principles.