|
| |
|
|
Investigation of Miniature Devices for Collection of Hydride Forming Elements in Atomic Spectrometry Methods
Krejčí, Pavel ; Čelechovská, Olga (referee) ; Janoš, Pavel (referee) ; Otruba, Vítězslav (referee) ; Dočekal, Bohumil (advisor)
Capability of a prototype of miniature collection device based on a strip of the molybdenum foil for collecting hydride forming elements (As, Se, Sb and Bi) was studied. The device was combined with a miniature hydrogen diffusion flame for detection by atomic absorption spectrometry. The conditions for trapping and subsequent vaporization of analytes of interest were optimized. A twin-channel hydride generation system was used for study of mutual interference effects of co-generated hydride forming elements. The influence of modification of the molybdenum surface with noble metals - Rh, Pt and Ir on trapping and vaporization processes was also studied and changes of microstructure of the foil surface after modification were investigated using scanning electron microscope equipped with energy dispersive x-ray analyzer and electron backscattered diffraction system. Complementary radiotracer and radiography experiments were performed in order to determine trapping efficiency and to assess the spatial distribution of collected analytes within the device. Practical application of the method was demonstrated on determination of antimony in water samples at trace level. Possibility of multi-element analysis was demonstrated by combining the collection device with atomization and excitation of the analyte in microwave induced plasma and with detection by atomic emission spectrometry method. The results of the experiments proved that tested miniature collection device is capable of trapping analytes that form volatile hydrides. This device can be coupled to various types of atomizers, typically used in spectrometry methods. Thus, very sensitive and specific detection of hydride forming elements can be performed.
|
|
|
Remote PC administration without IP address
Otruba, Vítězslav ; Skořepa, Michal (referee) ; Pfeifer, Václav (advisor)
The subject of the thesis is to design a concept of remote PC administration with intermediate unit, which allows the controlled computer not to have the public IP address. We don’t need to know its IP address at all, to take control over it. The designed system uses HTTP protocol to transport commands and replies. Central intermediate unit is the web server with PHP scripting, which cooperates with MySQL database server; the central data store. The commands are stored into MySQL database via web interface using PHP scripting. The target PC is running program in C++ language, which receives the commands by querying the PHP pages on web server, and sends the replies on them. The structure was designed as multi user system. Each user controls different target computer using unique login and password. In consideration of this is not allowed to use one login for two users at the same time and the users are automatically logged off in case of inactivity. As extra feature, not part of project’s main object, was designed the graphical user interface as add-on to the existing system, giving the user actual print-screen of target computer’s monitor. Also the mouse and keyboard functions are software-emulated. By creating the new autonomous data channel for screen pictures transfer, the new opportunity for bidirectional file transfer between controlling and controlled PC is opened.
|
|
|
Investigation of Miniature Devices for Collection of Hydride Forming Elements in Atomic Spectrometry Methods
Krejčí, Pavel ; Čelechovská, Olga (referee) ; Janoš, Pavel (referee) ; Otruba, Vítězslav (referee) ; Dočekal, Bohumil (advisor)
Capability of a prototype of miniature collection device based on a strip of the molybdenum foil for collecting hydride forming elements (As, Se, Sb and Bi) was studied. The device was combined with a miniature hydrogen diffusion flame for detection by atomic absorption spectrometry. The conditions for trapping and subsequent vaporization of analytes of interest were optimized. A twin-channel hydride generation system was used for study of mutual interference effects of co-generated hydride forming elements. The influence of modification of the molybdenum surface with noble metals - Rh, Pt and Ir on trapping and vaporization processes was also studied and changes of microstructure of the foil surface after modification were investigated using scanning electron microscope equipped with energy dispersive x-ray analyzer and electron backscattered diffraction system. Complementary radiotracer and radiography experiments were performed in order to determine trapping efficiency and to assess the spatial distribution of collected analytes within the device. Practical application of the method was demonstrated on determination of antimony in water samples at trace level. Possibility of multi-element analysis was demonstrated by combining the collection device with atomization and excitation of the analyte in microwave induced plasma and with detection by atomic emission spectrometry method. The results of the experiments proved that tested miniature collection device is capable of trapping analytes that form volatile hydrides. This device can be coupled to various types of atomizers, typically used in spectrometry methods. Thus, very sensitive and specific detection of hydride forming elements can be performed.
|
|
|
Remote PC administration without IP address
Otruba, Vítězslav ; Skořepa, Michal (referee) ; Pfeifer, Václav (advisor)
The subject of the thesis is to design a concept of remote PC administration with intermediate unit, which allows the controlled computer not to have the public IP address. We don’t need to know its IP address at all, to take control over it. The designed system uses HTTP protocol to transport commands and replies. Central intermediate unit is the web server with PHP scripting, which cooperates with MySQL database server; the central data store. The commands are stored into MySQL database via web interface using PHP scripting. The target PC is running program in C++ language, which receives the commands by querying the PHP pages on web server, and sends the replies on them. The structure was designed as multi user system. Each user controls different target computer using unique login and password. In consideration of this is not allowed to use one login for two users at the same time and the users are automatically logged off in case of inactivity. As extra feature, not part of project’s main object, was designed the graphical user interface as add-on to the existing system, giving the user actual print-screen of target computer’s monitor. Also the mouse and keyboard functions are software-emulated. By creating the new autonomous data channel for screen pictures transfer, the new opportunity for bidirectional file transfer between controlling and controlled PC is opened.
|
|
| |
guest ::
