Основи охорони праці

Навчальний посібник містить курс лекцій, теми рефератів та питання, що виносяться на семінарські заняття з дисципліни «Основи охорони праці» для студентів вищих педагогічних навчальних закладів всіх спеціальностей і напрямів підготовки за освітньо-кваліфікаційним рівнем «бакалавр» і курсів післядипломної освіти

Avant-propos

La chute des régimes communistes et l'instauration de démocraties pluralistes en Europe centrale et orientale, accompagnées de proclamations de rupture radicale avec le passé, ont engendré un bouleversement général des repères qui jusque-là permettaient les identifications individuelles et l'élaboration d'identités collectives dans toutes les sphères sociales. Le rejet obligé du passé a été décliné de différentes manières selon les pays, en fonction des diverses expériences du communisme (et de sa chute) dans chacune des sociétés concernées. Toutefois, si les modalités sont variables et les calendriers spécifiques, ces recompositions sociales et politiques se sont toutes inscrites dans un même cadre mental. La condamnation globale du communisme a favorisé des visions polarisées et simplifiées du passé, fondées sur des catégories binaires et des figures stéréotypées, plus ou moins marquées, de bourreaux et de victimes. Au-delà du consensus affiché dans le rejet et la condamnation du communisme, un examen plus fin du rapport au passé dans ces sociétés dites post-communistes souligne la difficulté d'élaborer un discours commun sur le passé (...)

Reconstructing charge-carrier dynamics in porous silicon membranes from time-resolved interferometric measurements

We performed interferometric time-resolved simultaneous reflectance and transmittance measurements to investigate the carrier dynamics in pump-probe experiments on thin porous silicon membranes. The experimental data was analysed by using a method built on the Wentzel-Kramers-Brillouin approximation and the Drude model, allowing us to reconstruct the excited carriers’ non-uniform distribution in space and its evolution in time. The analysis revealed that the carrier dynamics in porous silicon, with ~50% porosity and native oxide chemistry, is governed by the Shockley-Read-Hall recombination process with a characteristic time constant of 375 picoseconds, whereas diffusion makes an insignificant contribution as it is suppressed by the high rate of scattering

Porous Silicon Hydrogen Sensor at Room Temperature: The Effect of Surface Modification and Noble Metal Contacts

Porous silicon (PS) was fabricated by anodization of p-type crystalline silicon of resistivity 2-5 Ω cm. After formation, the PS surface was modified by the solution containing noble metal like Pd. Pd-Ag catalytic contact electrodes were deposited on porous silicon and on p-Silicon to fabricate Pd-Ag/PS/p-Si/Pd-Ag sensor structure to carry out the hydrogen sensing experiments. The Sensor was exposed to 1% hydrogen in nitrogen as carrier gas at room temperature (270C). Pd modified sensor showed minimum fluctuations and consistent performance with 86% response, response time and recovery time of 24 sec and 264 sec respectively. The stability experiments were studied for both unmodified and Pd modified sensor structures for a period of about 24 hours and the modified sensors showed excellent durability with no drift in response behavior

Detection of Hydrogen by Noble Metal Treated Nanoporous Si and ZnO Thin Films

Nanoporous silicon and nanoporous ZnO were prepared by the electrochemical anodization of crystalline Si and Zn substrates, respectively. To passivate the defect states and to improve the gas sensitivity the porous silicon and nano crystalline ZnO surfaces were treated with aqueous solution of PdCl2. The Pd modified sensors with Pd-Ag (26 %)/PS/Si/Al (MIS) and Pd-Ag (26 %)/ZnO/Zn (MIM) device structures were investigated regarding the hydrogen sensing performance. Both sensors showed promising performance in terms of operating temperature, response magnitude, response time and recovery time. While the PS MIS sensors showed optimum performance at room temperature the ZnO MIM sensors showed faster response at 50oC, both demonstrating long term stable operations

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-72077 Development of SiC-FET methanol sensor

A silicon carbide based field effect transistor (SiC-FET) structure was used for methanol sensing. Due to the chemical stability and wide band gap of SiC, these sensors are suitable for applications over a wide temperature range. Two different catalytic metals, Pt and Ir, were tested as gate contacts for detection of methanol. The sensing properties of both Ir gate and Pt gate SiC-FET sensors were investigated in the concentration range 0.3 – 5 % of methanol in air and in the temperature range 150–350ºC. It was observed that compared to the Ir gate sensor, the Pt gate sensor showed higher sensitivity, faster response and recovery to methanol vapour at comparatively lower temperature, with an optimum around 200ºC. Quantum-chemical calculations were used to investigate the MeOH adsorption and to rationalize the observed non-Langmuir behavior of the response functions. The methanol sensing mechanism of the SiC-FET is discussed

Development of SiC-FET methanol sensor

A silicon carbide based field effect transistor (SiC-FET) structure was used for methanol sensing. Due to the chemical stability and wide band gap of SiC, these sensors are suitable for applications over a wide temperature range. Two different catalytic metals, Pt and Ir, were tested as gate contacts for detection of methanol. The sensing properties of both Ir gate and Pt gate SiC-FET sensors were investigated in the concentration range 0.3–5% of methanol in air and in the temperature range 150–350 °C. It was observed that compared to the Ir gate sensor, the Pt gate sensor showed higher sensitivity, faster response and recovery to methanol vapour at comparatively lower temperature, with an optimum around 200 °C. Quantum-chemical calculations were used to investigate the MeOH adsorption and to rationalize the observed non-Langmuir behavior of the response functions. The methanol sensing mechanism of the SiC-FET is discussed.funding agencies|Swedish Research Council| VR 348-2007-6837 VR 621-2008-3229 VR 621-2008-4859 |</p

SiC-FET methanol sensors for process control and leakage detection

Two types of SiC based field effect transistor sensors, with Pt or Ir gate, were tested to detect methanol in the concentration range of 0–1600 ppm for both process control and leak detection applications. The methanol response was investigated both with and without oxygen, since the process control might be considered as oxygen free application, while the sensor is operated in air during leak detection. Pt sensors offered very fast response with appreciably high response magnitude at 200 °C, while Ir sensors showed both higher response and response time up to 300 °C, but this decreased considerably at 350 °C. Cross sensitivity effect in presence of oxygen, hydrogen, propene and water vapor was also investigated. The presence of oxygen improved the response of both sensors, which is favorable for the leak detection application. Hydrogen had a large influence on the methanol response of both sensors, propene had a negligible influence, while water vapor changed direction of the methanol response for the Pt sensor. The detection mechanism and different sensing behavior of Pt and Ir gate sensors were discussed in the light of model reaction mechanisms derived from hybrid density-functional theory quantum-chemical calculations