Browsing by Author "Koss, A."

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Emission spectra for analysing elements in clues using optical method [Articol]
(Universitatea de Stat „Alecu Russo“ din Bălţi, 2014) Evtodiev, S.; Koss, A.; Evtodiev, Igor
The following research was dedicated to the investigation of emission spectra of different elements and their use in the analysis of clues. The used equipment was a spectrometer, the "Red Tide USB-650", and an application called "Overture". The spectrometer has a spectral range from 350 nm to 1000 nm. It’s a very lightweight and portable device,not taking up much space and weighting only 190 g. The sensitivity of the device is 75 photons at a wavelength of 400 nm. The optical resolution of the spectrometer is 2 nm, while the program can display accurate graphs with a resolution of up to 0.1 nm. The spectrometer’s integration time ranges from 3 ms to up to 65 seconds, but typically it d oesn’t exceed 15 seconds. For very precise data recording the spectrometer can also use the optic fibres. The used program has a library of emission spectra of different elements. The experiment is performed by making the substance to emit photons by exciting it. The light from this substance is received by the spectroscope and the data are transmitted to the computer. The program generates an "Intensity-Wavelength" graph right away. But to analyse and to detect elements in clues a graph is not the only required thing. Luckily, we have access to the emission spectra library built into the program. Those can be enabled and disabled to detect if the given element is present in the earlier analysed substance.Such a method can be used to detect elements in clues using spectral analisys at remarkable speeds and accuracies.
The experimental study of real and ideal harmonic oscillators [Articol]
(Universitatea de Stat „Alecu Russo“ din Bălţ, 2014) Koss, A.; Evtodiev, S.; Evtodiev, Igor
The following research was dedicated to studying and experimenting with harmonic oscillators of all kinds. The used equipment was a portable computer, the “PASCO Spark”, a force sensor, 3 different springs and weights. The portable computer is responsible for storing the data received from the force sensor, and constructing a “Force-Time” graph. The force sensor has a range of ±50 N, an accuracy of 0.1 N and a recording speed of up to 1000 Hz. It is also equipped with a reset button to automatically set it to 0 N. The springs used in the experiment differed in damping. The first spring had a very low damping coefficient, so after the weight was released they continued oscillating for a very long time, fading away only very slightly. The second spring had a medium damping coefficient, so the time it took for the oscillations to fade was much shorter, then with the first spring. The third spring however had a very high damping coefficient, so the oscillations only continued for about 6 seconds. The experiment itself was performed by hanging a weight on the spring, and starting the data recording as soon as the weight is dropped. In all 3 experiments the data was recorded at a frequency of 100 Hz. Afterwards, the computer built “Force-Time” graphs for every experiment. This allowed us to visualize the difference between the 3 springs. The computer used in the experiment has a very useful ability of generating functions for graphs. This can be done in order to study ideal harmonic oscillations. The function generated from the graph continues forever, and can be used for further research in the field of beats, which are automatically calculated and simulated by the computer. Thanks to the precise data recording equipment human errors can be minimized, which leads to very little inaccuracies in calculations.