468 research outputs found
RISK MANAGEMENT AT TECHNICAL FACILITIES TYPE AND SITE SELECTION
Technical facilities are created by human activities, and their goal is to provide products or services for the humans´ lives. The technical facilities architecture is the object or the network. Each type of technical facility has its own specifics. Management of technical facilities´ safety is not easy and requires the application of specific engineering tools for coping with the expected risks. Due to complex architecture of majority of present technical facilities, their behaviours are sometimes unforeseeable, and therefore, special engineering tools need to be used at their type selection and sitting.
In the past, the attention was not overly given to type selection and location of technical facility. Therefore, some technical facilities projects have not been completed, or after completing their operation have not met the expectations, or even they began to make serious problems, which meant substantial economic losses. Therefore, the book “Risk management at technical facilities type and site selection” deals with the problem of specification of the type of technical facilities and their location in the territory. It summarizes results of specific research performed in project “Řízení rizik a bezpečnost složitých technologických objektů (RIRIZIBE)“ CZ.02.2.69/0.0/0.0/ 16 _018/000”.
Since, the deciding body on the subject is the public administration, they are compiled decision support and the risk management plan
RISK MANAGEMENT AT TECHNICAL FACILITIES DESIGNING, BUILDING AND COMMISSIONING
The publication subject is to show the risk management of complex technical facilities at a stage involving the design, construction, outfit by technology equipment, testing and commissioning. The safety of this technical facility is related to the entire technical facility because, as a result of the interconnections among different parts, the set of the safe parts is generally not safe. The safety also considers the dynamic evolution of the world. Therefore, it is going on managing the risks caused by all possible causes in time and space.
Based on the original database of failures and accidents of technical facilities, which also included weaknesses in the area of design, building, construction, testing and commissioning, they are determined the basic categories of risk causes. Through the procedures of advanced risk disciplines, there are developed the tools for working with risks in the monitored stage of the technical facility aimed at ensuring the technical facility safety throughout its life time, namely: decision support system; and risk management plan. Both tools are in two versions.
The book shortly summarizes results of specific research performed in project “Řízení rizik a bezpečnost složitých technologických objektů (RIRIZIBE)“ CZ.02.2.69/0.0 /0.0/16_018/000”. The detail results are in original Czech monograph, which is cited
Twenty Years of Rad-Hard K14 SPAD in Space Projects
During last two decades, several photon counting detectors have been developed in our laboratory. One of the most promising detector coming from our group silicon K14 Single Photon Avalanche Diode (SPAD) is presented with its valuable features and space applications. Based on the control electronics, it can be operated in both gated and non-gated mode. Although it was designed for photon counting detection, it can be employed for multiphoton detection as well. With respect to control electronics employed, the timing jitter can be as low as 20 ps RMS. Detection efficiency is about 40%in range of 500 nm to 800 nm. The detector including gating and quenching circuitry has outstanding timing stability. Due to its radiation resistivity, the diode withstands 100 krad gamma ray dose without parameters degradation. Single photon detectors based on K14 SPAD were used for planetary altimeter and atmospheric lidar in MARS92/96 and Mars Surveyor ’98 space projects, respectively. Recent space applications of K14 SPAD comprises LIDAR and mainly time transfer between ground stations and artificial satellites. These include Laser Time Transfer, Time Transfer by Laser Link, and European Laser Timing projects
Dimethyl ether as a renewable fuel for diesel engines
ArticleThe area of automotive fuel, or fuel components, which can be produced from biomass
also includes dimethyl ether, otherwise known as DME. The issue of the use of DME as a fuel is
one which has been monitored until recently. Biomass can also be used as the raw material for
the production of DME. DME has therefore replaced the previously-used CFCs
(chlorofluorocarbons), which are now banned for their role in dangerous levels of ozone
depletion. With regard to its physical properties and combustion characteristics, it is currently
expected that DME will soon apply significantly as a fuel in the municipal sector and in
households, and as an alternative fuel for motor vehicles with diesel engines. DME is a suitable
fuel for diesel engines and can be considered as one of the most promising diesel fuel
replacements. DME is a suitable fuel for diesel engines mainly due to its low self-ignition
temperature and good cetane figures. It is well miscible with most organic solvents and because
the polar solvent is water-immiscible. The advantage is its high levels of purity, and its being free
of sulphur, nitrogen, or metals. The physical properties of DME are very similar to the physical
properties of LPG. DME requires relatively complex and costly fuel accessories, but the original
compression ratio of the diesel engine is maintained. A diagram of the fuel system is illustrated
in the paper. The paper analyses the dependence of vapour pressure on temperature, the
dependence of the density on temperature, kinematic viscosity, the flash point, the boiling point,
and the solubility of water. The objective is to evaluate this interesting energy source for
applications in diesel engines
Diagnostics of hydraulic fluids used in aviation
ArticleDiagnostics is a maintenance industry that monitors performance, parameters, and
follow
–
up. Diagnosing hydraulic fluids means comparing the parameters of the used hydr
aulic
fluid sample to the parameters of the clean fluid. It is also essentia
l to monitor the limit values
either by the aircraft manufacturer or by the manufacturer of the hydraulic fluid. This means
that the manufacturer recommends the limitations of the
liquid parameters. The measurements
of the fluid samples give an overview of the liquid quality. Most businesses focus on so
–
called
proactive maintenance. The main senses and objectives of proactive maintenance are: lubricant
sample analysis, lubricant sta
tus, machine status, next step recommendation, database saving
and trend analysis. This article focuses on the quality of hydraulic fluid focused in aviation. The
aim of the article was to determine the properties of the hydraulic fluid used in the A320 ai
rcraft
family, determine the interval of its exchange. Monitoring the state of the hydraulic fluid could
contribute to the timely detection of the problem, thus avoiding a failure of the device or the
system as a
whole. The tracking proposal is an integral
part of this article
The Czech adaptation of the Klein et al’s unidimensional targer-neutral scale of commitment
This study describes the process of translating, adapting and validating the Klein et al’s Unidimensional Target-neutral Scale of Commitment (KUT) into Czech. The KUT scale is a self-report scale that consists of four items. The scale was adapted using three independent translations into Czech, one back-translation into English by a native speaker, assessment by experts, and piloting in cognitive interviews with 13 respondents. The study also provides evidence on the scale’s reliability and validity for measuring organizational commitment defined as a psychological bond with an organization. The analyses were based on data obtained from 811 Czech-speaking adults working for Czech organizations. Using ordinal structural equation models (SEM) estimated on the polychoric correlation matrices with the robust WLSMV estimator, the Czech adaptation of the KUT scale showed similar psychometric characteristics to the original English version. The Czech KUT scale is unidimensional and internally consistent. All items have high factor loadings. The scale is invariant across groups defined by gender, workload and the sector in which the organization operates. The convergent validity is supported by the fact that the organizational commitment measured by the Czech KUT scale relates positively to job satisfaction, self-rating of job performance, extra-role behaviour and negatively to turnover intention. The Czech KUT scale also proved incremental validity to job performance over job satisfaction measured by Job Descriptive Survey. Therefore, the scale is a valid instrument for measuring organizational commitment within the Czech-speaking population. It can be used for organizational surveys as well as for research within the organizations
Permutation Entropy and Signal Energy Increase the Accuracy of Neuropathic Change Detection in Needle EMG
Background and Objective. Needle electromyography can be used to detect the number of changes and morphological changes in motor unit potentials of patients with axonal neuropathy. General mathematical methods of pattern recognition and signal analysis were applied to recognize neuropathic changes. This study validates the possibility of extending and refining turns-amplitude analysis using permutation entropy and signal energy. Methods. In this study, we examined needle electromyography in 40 neuropathic individuals and 40 controls. The number of turns, amplitude between turns, signal energy, and “permutation entropy” were used as features for support vector machine classification. Results. The obtained results proved the superior classification performance of the combinations of all of the above-mentioned features compared to the combinations of fewer features. The lowest accuracy from the tested combinations of features had peak-ratio analysis. Conclusion. Using the combination of permutation entropy with signal energy, number of turns and mean amplitude in SVM classification can be used to refine the diagnosis of polyneuropathies examined by needle electromyography
Rufous Common Cuckoo chicks are not always female
This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this recordThe Common Cuckoo (hereafter Cuckoo) shows two adult plumage morphs—adult male plumage is grey and adult females are either grey or, less frequently, rufous. The situation is less clear in juveniles, as both sexes exhibit variable proportions of grey and rufous colour. We thus describe the patterns related to sex-specific plumage colour variation in a central European Cuckoo population. We genetically determined the sex of 91 Cuckoo chicks and using visual classification of photographs we scored juvenile plumage colouration of individual chicks into five classes based upon the increasing proportion of rufous colour on feathers. To verify these scores, we sampled chick feathers and quantified the proportion of rufous colour of individual feathers by digital image analysis. We found that juvenile females had a higher proportion of rufous colour of feathers than juvenile males. However, the difference was marginally non-significant based on visual inspection alone, and some male chicks even showed intensively rufous plumage like those of juvenile females. In contrast, we captured only grey adult males (n = 37), while five out of 20 adult females were rufous. The rufous colour of Cuckoo feathers considerably differed from the grey colour and the difference seemed to be larger in adults than in juveniles. We show that chicks, unlike adult females, cannot be visually assigned to either of the adult morphs. Therefore, we encourage further investigation of Cuckoo plumage colouration across the species’ range to examine the process of plumage maturation. A detailed genetic analysis is necessary to understand the origin of Cuckoo feather colouration.This study was supported by the Czech Science Foundation (project 17-12262S) and by the Institutional Research Plan (RVO: 68081766)
Inverted Solution Processable OLEDs Using a Metal Oxide as an Electron Injection Contact
A new type of bottom-emission electroluminescent device is described in which a metal oxide is used as
the electron-injecting contact. The preparation of such a device is simple. It consists of the deposition of a
thin layer of a metal oxide on top of an indium tin oxide covered glass substrate, followed by the solution
processing of the light-emitting layer and subsequently the deposition of a high-workfunction (air-stable)
metal anode. This architecture allows for a low-cost electroluminescent device because no rigorous
encapsulation is required. Electroluminescence with a high brightness reaching 5700 cd m–2 is observed
at voltages as low as 8 V, demonstrating the potential of this new approach to organic light-emitting diode
(OLED) devices. Unfortunately the device efficiency is rather low because of the high current density
flowing through the device. We show that the device only operates after the insertion of an additional
hole-injection layer in between the light-emitting polymer (LEP) and the metal anode. A simple model
that explains the experimental results and provides avenues for further optimization of these devices is
described. It is based on the idea that the barrier for electron injection is lowered by the formation of a
space–charge field over the metal-oxide–LEP interface due to the build up of holes in the LEP layer close
to this interfac
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