BackgroundIt is possible to see a number of spectrophotometers produced by commercial purposes developed in line with the technical advices identified by the International Commission on Illumination (CIE) in universities' chemistry labs. These devices are employed in measuring and testing materials with unidentified characteristics as well as reporting the results. However, these systems are not modular in design and do not allow updates or modifications. Moreover, when the literature is reviewed, it can be seen that the researches on computer-controlled devices is limited. It is also reported that the devices with user interfaces bring advantages to researchers in terms of time efficiency and safety.
MethodsIn this study, a computer-controlled, modular and low-cost spectrophotometer is designed to measure material densities contained within liquid samples. The proposed system is composed of a main unit, a data acquisition unit and a user interface. All tasks and relevant arrangements involved in a spectrophotometer application are controlled through an interface developed on LabVIEW graphical development platform; the results of the measurements can be monitored in real time, and it is also possible to store data. Thanks to the modular design, it became possible to change and update the relevant stage as needed. The waveform filter can be selected specifically as visible range, ultraviolet range or both depending on the application.
ResultsThe experiment was conducted in the visible range and a waveform filter between 400 and 700 nm was used. In the experiments, an easily accessible materials-methylene blue and copper sulfate solutions-were preferred as samples. For these solutions, the waveforms that give the best absorption values were identified and the density was measured at those values. Furthermore, the nonlinearity and repeatability characteristics of the proposed spectrophotometer were analyzed. For this purpose, measured values were compared with the acquired values from another commercial instrument that is already used in medical field. Measurements were repeated 50 times for copper sulfate and 43 times for methylene blue solutions.
ConclusionsAfter statistical analysis, it was observed that the reliability of the proposed system is high.
In this study, investigation of video processing method which is a new technique for precision displacement measurement is presented. The video processing method was integrated with an interferometric system and the thermal expansion results and linear thermal expansion coecients of a heated sample metals were compared with theoretical results. Michelson interferometer setup was used in our study due to its advantages in precision displacement information of a visual output, called interferograms. In the experimental studies, signals of interferograms containing displacement information were obtained from the measurement system. The amount of displacement in the sample metals under the temperature variation due to thermal expansion was measured with the analysis program, written in Matlab/Simulink environment, with a micrometer precision. The measured displacement amounts were compared with the results of theoretical calculations. According to the theoretical values, the relative error of the values measured with video processing based method, was found found to be 0.3%
The continuous development of technology and, accordingly, people's interest in technological devices is increasing. Electric powered devices generate electricity and magnetic fields. The intensity of electric and magnetic fields is restricted by international organizations and limit values by Turkey's Information Technologies and Communication Authority (BTK). The values of the electromagnetic field generated by the base stations are monitored by the BTK. The limit values determined by the BTK are more stringent than those set by international organizations. The intensity of the electromagnetic field varies according to the distance and power to the system. In this study, electromagnetic field pollution in Marmara University Başıbüyük Campus was analyzed periodically and according to different weather conditions. Measurements were performed at 19 different points and the results were mapped. SRM 3006 model selective radiation meter was used in the measurement. Measurement results were compared with international limit values and evaluated. The limit value determined by international organizations for the environment is 61 V/m and the limit value determined by BTK is 42 V/m. 12-day average electric field is 1.53 V/m for periodical measurements. The average electric field in sunny weather is 1.9 V/m, 1.28V/m in rainy weather and 1.39V/m in cloudy weather. Gas Discharge Visualization technique was used to observe the possible changes in the energy and stress situation of the different electromagnetic field points within the campus. Energy and stress measurement with this technique was performed with Bio-well device. According to the measurement results, no change in stress and energy status was observed.
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