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Analysis of repaired gas turbine and compressor blades

In order to reach desired levels of efficiency and power output of jet engines, advanced gas turbine and compressor blades made from Ti‐6AL‐4V alloy operate at very high temperatures (up to 600°C) and speeds (up to 10000 rpm) [3–4]. Pressure of springing streams and inertial forces are main reasons of stress appearance in the blades. Besides that, blade usually could be out of action after one's edges had become damaged under temperature or foreign object hit negative influence. High cycle fatigue (HCF) accounts for 56 % of major aircraft engine failures and ultimately limits the service life of most critical rotating components. Extensive inspection and maintenance programs have been developed to detect, renew and replace defected blades, to avoid catastrophic engine failure. Various modern technologies including laser cladding (filling layers of sprayed material) allow prolongation of blades’ life by damaged part's renovation with alternate material. The general aim of the present work concludes of blades’ mechanical bahavour comparison before and after renewal. Santrauka Šiame darbe aprašoma, kaip buvo atliekama suremontuotų turbinos ir kompresoriaus menčių atsparumo analizė. Svarbiausia buvo palyginti ekvivalentinių įtampų rezultatus iki ir po menčių renovavimo alternatyvia medžiaga. Modelių, kurie buvo suprojektuoti kompiuterine programa SolidWorks, medžiaga buvo keičiama tose darbinės mentės briaunos vietose, kur buvo galimi eksploataciniai defektai. First Published Online: 14 Oct 2010 Reikšminiai žodžiai: turbinos mentė, kompresoriaus mentė, modeliavimas, srautai, vidinis vėdinimas, nuostolių simuliavimas, medžiagų pakitimas, Von Mise ekvivalentinis stresas, pajėgumas, eksperimentas, rezultatų palyginimas

Physiological stress and higher reproductive success in bumblebees are both associated with intensive agriculture

Free-living organisms face multiple stressors in their habitats, and habitat quality often affects development and life history traits. Increasing pressures of agricultural intensification have been shown to influence diversity and abundance of insect pollinators, and it may affect their elemental composition as well. We compared reproductive success, body concentration of carbon (C) and nitrogen (N), and C/N ratio, each considered as indicators of stress, in the buff-tailed bumblebee (Bombus terrestris). Bumblebee hives were placed in oilseed rape fields and semi-natural old apple orchards. Flowering season in oilseed rape fields was longer than that in apple orchards. Reproductive output was significantly higher in oilseed rape fields than in apple orchards, while the C/N ratio of queens and workers, an indicator of physiological stress, was lower in apple orchards, where bumblebees had significantly higher body N concentration. We concluded that a more productive habitat, oilseed rape fields, offers bumblebees more opportunities to increase their fitness than a more natural habitat, old apple orchards, which was achieved at the expense of physiological stress, evidenced as a significantly higher C/N ratio observed in bumblebees inhabiting oilseed rape fields

Serotoninergic Modulation of Phototactic Variability Underpins a Bet-Hedging Strategy in Drosophila melanogaster

When organisms' environmental conditions vary unpredictably in time, it can be advantageous for individuals to hedge their phenotypic bets. It has been shown that a bet-hedging strategy possibly underlies the high inter-individual diversity of phototactic choice in Drosophila melanogaster. This study shows that fruit flies from a population living in a boreal and relatively unpredictable climate have more variable variable phototactic biases than fruit flies from a more stable tropical climate, consistent with bet-hedging theory. We experimentally show that phototactic variability of D. melanogaster is regulated by the neurotransmitter serotonin (5-HT), which acts as a suppressor of the variability of phototactic choices. When fed 5-HT precursor, boreal flies exhibited lower variability, and they were insensitive to 5-HT inhibitor. The opposite pattern was seen in the tropical flies. Thus, the reduction of 5-HT in fruit flies' brains may be the mechanistic basis of an adaptive bet-hedging strategy in a less predictable boreal climate

Modern Vacuum Tube Amplifier : VFD as a triode

The goal of this thesis is to apply knowledge of analogue circuits to demonstrate performance of VFD based triode Nutube designed by Korg. After reading this material, the user is able to understand advantages and disadvantages of this component and further development problems. This study includes information of vacuum tubes history and circuit design, theory of amplifiers design and audio measurements methods, which can be useful for further work of audio engineers. Study discusses the main principles of amplification of signal in the low frequency range (of audible frequency). The result of the project is an amplifiers based on Nutube 6p1 and its measurements which will demonstrate efficiency and benefits of this component and analysis of future perspectives of the device. The prime goal of the project was achieved successfully. Four amplifiers for different purposes was designed and measured. Modern VFD vacuum tube demonstrated itself as a tube which can provide “tube sound” with low supply voltages. However, there are problems with Nutube 6p1 which makes it useless in audio systems with high fidelity

Impact of Smart Economy on Smart Areas and Mediation Effect of National Economy

The smart city presupposes the integration of different parts—Smart Economy, Smart Environment, Smart People, Smart Living, Smart Mobility, and Smart Governance. The integration assumes the certain relations between them. There are researches considering the impact of separate economic indicators on specific smart area or solutions. Nevertheless, the authors have not come across any studies considering the mutual impact of these areas. The goal of the research is to determine the direct effects of smart economy on other smart components and the indirect (mediation) impact of general indicators of national economy on smart domains. The model was estimated using the PLS-SEM technique tested in SmartPLS-3.3.7. software. The sample included statistical data on the indicators, received from Eurostat Database and Latvian Statistical Office. Data referred to Latvia for years 2009–2019. As a result, the hypotheses that Smart Economy has direct impact on smart people, smart living, smart mobility, smart environment, and smart society were supported. The mediation effect of general indicators of national economy was confirmed only for the smart society domain; other hypotheses were rejected. The obtained results can be practically applied by the authorities responsible for sustainable development of smart areas. The results of mediation effect can be especially interesting for countries that do not present a very high level of economic development but are developing smart, sustainable cities

Effects and Externalities of Smart Governance

The concept of a smart city is widely implemented all over the world, and this fact creates both possibilities and new challenges for all participants and stakeholders of the process. This study examines the implementation of smart governance in the context of smart cities. The goal of the research is to distinguish between the effects and externalities of the smart governance domain, both positive and negative ones; the effects and externalities are elicited from the outcomes of smart governance implementation revealed from a review of scientific publications devoted to the results, barriers, and facilitators of smart governance functioning. The publications were selected according to a systematic review methodology, then the selected articles were analyzed and the factors that foster the processes of smart governance implementation (facilitators) or vice versa hamper the acquisition of results (barriers), as well as the outcomes of smart governance, were extracted. The extracted factors were attributed to six areas: Information, Efficiency, Citizen-Centricity, Transparency, Digital Divide, and Regulation. Further, the outcomes of smart governance implementation were distinguished as effects and externalities, which were both positive and negative

Impact of Smart Economy on Smart Areas and Mediation Effect of National Economy

The smart city presupposes the integration of different parts—Smart Economy, Smart Environment, Smart People, Smart Living, Smart Mobility, and Smart Governance. The integration assumes the certain relations between them. There are researches considering the impact of separate economic indicators on specific smart area or solutions. Nevertheless, the authors have not come across any studies considering the mutual impact of these areas. The goal of the research is to determine the direct effects of smart economy on other smart components and the indirect (mediation) impact of general indicators of national economy on smart domains. The model was estimated using the PLS-SEM technique tested in SmartPLS-3.3.7. software. The sample included statistical data on the indicators, received from Eurostat Database and Latvian Statistical Office. Data referred to Latvia for years 2009–2019. As a result, the hypotheses that Smart Economy has direct impact on smart people, smart living, smart mobility, smart environment, and smart society were supported. The mediation effect of general indicators of national economy was confirmed only for the smart society domain; other hypotheses were rejected. The obtained results can be practically applied by the authorities responsible for sustainable development of smart areas. The results of mediation effect can be especially interesting for countries that do not present a very high level of economic development but are developing smart, sustainable cities

Approach the National Quality Audit System for Radiotherapy in Latvia

It is very important to make National Quality Audit to ensure accurate conformal RT delivery. It is necessary to develop an Audit system to inspect all Conformal RT and IMRT delivery chain including the Quality checks of linear accelerator, Multileaf Collimator (MLC), Computer Tomography (CT) scanner or simulator, target and tissue delineation, plan evaluation, and delivery