Search Results

You are looking at 141 - 150 of 795 items for :

Clear All
Open access

Milan Holický, Jana Marková and Miroslav Sýkora

Abstract

The target reliability levels recommended in national and international documents vary within a broad range, while the reference to relevant costs and failure consequences is mentioned only very vaguely. In some documents the target reliability index is indicated for one or two reference periods (1 year, 50 years or life-time) without providing appropriate links to the design working life. This contribution attempts to clarify the relationship between the target reliability levels, costs of safety measures, failure consequences, reference periods and the design working life

Open access

Carmen Dobjanschi and Rucsandra Dănciulescu Miulescu

Abstract

Women with gestational diabetes mellitus (GDM) have an increased lifetime risk of developing type 2 diabetes mellitus (T2DM). GDM has a substantial impact on maternal and foetal short and long-term health. Risk factors for GDM may be genetic or nongenetic and have been analysed in numerous studies. Researches in recent years allowed the identification of other risk factors for GDM except for those already known. Knowledge and identification of all risk factors for GDM allows the elaboration of a prevention strategy of T2DM, it may influence the screening, diagnosis, and, subsequently, treatment modalities for this disease.

Open access

Ewa Kuligowska

Abstract

The material given in this paper delivers the procedure for numerical approach that allows finding the main practically important safety characteristics of the complex technical systems at the variable operation conditions including operating environment threats. The obtained results are applied to the safety evaluation of the maritime ferry technical system. It is assumed that the conditional safety functions are different at various operation states and have the exponential forms. Using the procedure and the program written in Mathematica, the considered maritime ferry technical system main characteristics including: the conditional and the unconditional expected values and standard deviations of the system lifetimes, the unconditional safety function and the risk function are determined.

Open access

Jacek Paś and Sławomir Buchla

Abstract

The paper presents basic issues regarding the operation of the electronic device (ED). Electronic device - is a collection of packages (e.g. integrated circuits, processors, memories, etc.) and (or) passive and active electronic components (e.g. resistors, capacitors, transistors, diodes, etc.) that are related to each other in a functional way. By cooperating with each other, they implement a selected useful function that results from the purpose of a given device. The operation process includes technical, administrative and logistical tasks that are undertaken during the ED’s lifetime. The most important goal of all activities is to correctly perform all the functions useful for a given technical object, in this case the ED.

Open access

Lihua Ma

The Benefits of Inclined-Orbit Operations for Geostationary Orbit Communication Satellites

Geostationary orbit (GEO) communication satellites can be extended in lifetime by switching to inclined-orbit operations. In this mode, a small amount of propellant is reserved to maintain the assigned orbit longitude. Inclination is allowed to build up at a rate of approximately 0.8○ per year. Developing these space resources can bring out a number of benefits. Besides communication application, these satellites can be used to construct navigation constellation of the Chinese Area Positioning System (CAPS). In this present paper, the realization way of communication and navigation applications is studied and the benefits and problems are explained.

Open access

Juraj Ružbarský and Witold Biały

Abstract

The article deals with the formation and spread of cracks from thermal fatigue in metallic forms. For a detailed examination of the problem, it is necessary to describe the thermal side of the process and the mechanism of mechanical stressing of the material. For the heating of the material is valid where the thermal diffusivity of the material is exercised by the decision method. The stress of the material by heating from the die casting metal depends mainly on the physical properties of the material when the calculated stress does not exceed the yield point. Also, with the help of dislocations write the life to the origin of the cracks in the cycles eventually the share of this lifetime on the total lifetime in dependence on the mechanical and physical properties of the material. During operation tests the occurrence of the cracks on the mold surface was initiated by the inclusion or concentration of stress in the knurling effect of fine grooves after grinding. Other cracks occurred in the undersurface layer and their direction was statistically accidental.

Open access

E. Snircova, T. Kulhan, G. Nosalova and I. Ondrejka

Abstract

Attention-deficit/hyperactivity disorder (ADHD) in childhood or adolescence is associated with a significantly higher lifetime risk of oppositional defiant disorder, anxiety disorder, conduct disorder, among others. Reports of co-morbidity rates are variable and influenced by assesment methodology and refferal bias, and may reflect lifetime rates within clinical groups. Up-to date studies revealed that as many as 85% of patients with ADHD have at least one psychiatric comorbidity and approximately 60% have at least two. Research and clinical practice has shown that having multiple co-existing psychiatric problems increase the severity of ADHD and behavioural problems, and is associated with incereased psychosocial impairment. The high rate of psychiatric problems co-occuring with ADHD has strong implications for the management of these patients. The presence of co-existing psychiatric conditions may moderate the response to treatment of ADHD and ADHD treatments may adversely affect and exacerbate the symptoms of the co-morbit condition. The aim of this article was to summarize the use of atomoxetine in the most frequent co-morbid disorders accompaining ADHD, ODD (oppositional defiant disorder) and anxiety, and to emphazise decrease of co-morbid symptoms with treatment of atomoxetine what exhort us to think about them as about possible subtypes of ADHD.

Open access

Paweł Lindstedt, Tomasz Sudakowski and Artur Kułaszka

Abstract

The new approach for the assessment of reliability condition of the exploited system, based on the appropriate analysis of changes in the current parameters of technical condition aRb and the regulation condition aRc, determined from the compressed condition equation (1 and 2). While analyzing the course of momentary parameters for technical condition aRb and the regulation condition aRc, it was observed that the parametric and momentary damages can be identified on the basis of quantitative relations between momentary threshold value dpr and corresponding momentary permissible value dpr dop, which are calculated from equation (7, 8, 9) resulting from Lindeberg–Levy’s theorem. It is assumed that the damages are prevailing, when for the moment θi: >dpri> dpr dopi. With the number of damages (damage map), reliability parameters for each moment of exploitation of technical object (before the catastrophic damages will occur) can be determined. Parametric damages (expected lifetime E(T) and standard deviation of expected lifetime σE(T) provides the reasonable information for the appropriate planning of the servicing of exploitative objects.

Open access

Domokos L, Ábrám Z, Sebesi Sz and Finta Hajnal

Abstract

Introduction: In 2010 Romania was ranked fourth in the European Union regarding the prevalence of ethnobotanical drug use with psychotropic effect. The main purpose of our survey was to collect data on substance use and assess drug consumption habits among participants at the 2011 Peninsula Music Festival in Tîrgu Mureș, Romania. Material and method: The study was carried out as a cross-sectional survey in a sample of 256 persons, using an anonymous, self-administered structured questionnaire, containing questions about the consumption patterns of illegal psychoactive drugs, as well as sociodemographic data which could influence drug consumption (age, gender, educational level, marital status of parents). Results: Ethnobotanical drug consumption had the highest lifetime prevalence (37.7%), the second most often used drug was cannabis (marijuana) with a lifetime prevalence of 35.2%. Males and females differed significantly in the use of marijuana (p = 0.023) and ethnobotanical drugs (p = 0.008) in the last 12 months, male respondents used more of these psychoactive substances. In the case of children with divorced parents the last 12 months marijuana use (p = 0.032) and ethnobotanical drug use (p = 0.013) was significantly higher than in the case of children whose parents were not divorced. Conclusions: The survey results show the importance of the development of health education programs and drug-prevention strategies for vulnerable goups (festival visitors, minors, children with divorced parents)

Open access

B. Lipowska, J. Witek, T. Wala, A. Karwiński, P. Wieliczko, M. Asłanowicz and A. Ościłowski

Abstract

Trials of cast steel filtration using two types of newly-developed foam filters in which carbon was the phase binding ceramic particles have been conducted. In one of the filters the source of carbon was flake graphite and coal-tar pitch, while in the other one graphite was replaced by a cheaper carbon precursor. The newly-developed filters are fired at 1000°C, i.e. at a much lower temperature than the currently applied ZrO2-based filters. During filtration trials the filters were subjected to the attack of a flowing metal stream having a temperature of 1650°C for 30 seconds.

Characteristic of the filters’ properties before and after the filtration trial were done. It was found, that the surface reaction of the filter walls with molten metal, which resulted in local changes of the microstructure and phase composition, did not affect on expected filter lifetime and filtration did not cause secondary contamination of cast steel.