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EN
In the present time, advanced high strength steel (AHSS) has secured a dominant place in the automobile sector due to its high strength and good toughness along with the reduced weight of car body which results in increased fuel efficiency, controlled emission of greenhouse gases and increased passengers’ safety. In the present study, four new advanced high strength steels (AHSS) have been developed using three different processing routes, i.e., thermomechanical controlled processing (TMCP), quenching treatment (QT ), and quenching & tempering (Q&T) processes, respectively. The current steels have achieved a better combination of the high level of strength with reasonable ductility in case of TMCP as compared to the other processing conditions. The achievable ultrahigh strength is primarily attributed to mixed microstructure comprising lower bainite and lath martensite as well as grain refinement and precipitation hardening.
EN
Quality of service parameters of cognitive radio, like, bandwidth, throughput and spectral efficiency are optimized using adaptive and demand based genetic algorithm. Simulation results show that the proposed method gives better real life solution to the cognitive radio network than other known approach.
3
Content available remote Health and environmental applications of gut microbiome: a review
EN
Life on Earth harbours an unimaginable diversity of microbial communities. Among these, gut microbiome, the ecological communities of commensal, symbionts (bacteria and bacteriophages) are a unique assemblage of microbes. This microbial population of animal gut helps in performing organism’s physiological processes to stay healthy and fit. The role of these microbial communities is immense. They continually maintain interrelation with the intestinal mucosa in a subtle equilibrium and help the gut for different functions ranging from metabolism to immunologic functions like upgradation of nutrient-poor diets, aid in digestion of recalcitrant food components, protection from pathogens, contribute to inter- and intra-specific communication, affecting the efficiency as disease vectors etc. The microbial diversity in the gut depends upon environmental competition between microbes, their sieving effects and subsequent elimination. Due to wide diversity of anatomy and physiology of the digestive tracts and food habits, the gut microbiome also differs broadly among animals. Stochastic factors through the history of colonization of the microbiome in a species and in situ evolution are likely to establish interspecies diversity. Moreover, the microbes offer enormous opportunity to discover novel species for therapeutic and/or biotechnological applications. In this manuscript, we review the available knowledge on gut microbiome, emphasising their role in health and health related applications in human.
EN
In the present study, the effect of tool rotational speed on microstructure and mechanical properties of friction stir welded joints between commercially pure copper and 6351 Al alloy was carried out in the range of tool rotational speeds of 300-900 rpm in steps of 150 rpm at 30 mm/minutes travel speed. Up to 450 rpm, the interface of the joints is free from intermetallics and Al4 Cu9 intermetallic has been observed at the stir zone. However, Al4 Cu9 intermetallic was observed both at the interface and the stir zone at 600 rpm. At 750 and 900 rpm tool rotational speed, the layers of AlCu, Al2 Cu3 and Al4 Cu9 intermetallics were observed at the interface and only Al4 Cu9 intermetallics has been observed in the stir zone. The maximum ultimate tensile strength of ~207 MPa and yield strength of ~168 MPa along with ~6.2% elongation at fracture of the joint have been obtained when processed at 450 rpm tool rotational speed.
EN
In this study, friction stir welding of dissimilar 304 stainless steel and commercially pure aluminium was performed under the following condition of tool rotational speed 1000 rpm, traverse speed 60 mm/min and tool tilt angle 2 degree. Microstructural characterisation was carried out by optical microscope, scanning electron microscope (SEM). Optical images shows that the microstructural change is very minimum in steel side when compared to aluminium side due to the difference in mechanical and thermal properties. The intermetallic compound Al3Fe was observed at the interfacial region and stir region of the welded joint. The maximum ultimate tensile strength is 78% of commercially pure aluminium base metal. Microhardness profile was measured across the weld interface and the maximum value reaches at the stir zone due to the formation of intermettalics.
EN
Bone quality varies from one patient to another extensively; also, Young’s modulus may deviate up to 40% of normal bone quality, which results into alteration of bone stiffness immensely. The prime goal of this study is to design the optimum dental implant considering the mechanical response at bone implant interfaces for a patient with specific bone quality. Method. 3D model of mandible and natural molar tooth were prepared from CT scan data while, dental implants were modelled using different diameter, length and porosity and FE analysis was carried out. Based on the variation in bone density, five different bone qualities were considered. First, failure analysis of implants, under maximum biting force of 250N had been performed; next, the implants, those survived were selected for observing the mechanical response at bone implant interfaces under common chewing load of 120N. Result. Maximum Von Mises stress did not surpass the yield strength of the implant material (TiAl4V). However, factor of safety of 1.5 was considered and all but two dental implants survived the design stress or allowable stress. Under 120N load, distribution of Von Mises stress and strain at the bone-implant interface corresponding to the rest of the implants for five bone conditions were obtained and enlisted. Conclusion. Implants, exhibiting interface strain within 1500-3000 microstrain range show the best bone remodelling and osseointegration. So, implant models, having this range of interface strains were selected corresponding to the particular bone quality. A set of optimum dental implants for each of the bone qualities were predicted.
EN
The impact of climate change on annual air temperature has received a great deal of attention from climatologists worldwide. Many studies have been conducted to illustrate that changes in temperature are becoming evident on a global scale. Air temperature, one of the most important components of climate parameters, has been widely measured as a starting point towards the apprehension of climate change and variability. The main objective of this study is to analyse the temporal variability of mean monthly temperature for the period of 1941 to 2010 (70 years). To detect the magnitude of trend in mean monthly temperature time series, we have used non-parametric test methods such as The Mann-Kendall test, often combined with the Theil-Sen’s robust estimate of linear trend. Whatever test is used, the user should understand the underlying assumptions of both the technique used to generate the estimates of a trend and the statistical methods used for testing. The results of this analysis reveal that four months – January, February, March and December – indicate a decreasing trend in average temperature, while the remaining eight months have an increasing trend. The magnitude of Mann-Kendall trend statistic Zc for this declining temperature and the magnitude of slope for the months of January, February and December are confirmed at the high significance levels of α = 0.001, 0.01 and 0.1 respectively. Though, the overall trend is positive for monthly as well as seasonally efficient time series.
8
Content available remote Korozja wyrobów MgO-C w strefie żużla kadzi stalowniczej
PL
Opracowano model laboratoryjny procesów korozji z uwzględnieniem szybko następującego nasycania się porcji żużla i kontrolowanego gradientu temperatury w warstwie badanych próbek. Przez dobór częstotliwości rezonansowej i odległości metalu od cewki uzyskano prędkość metalu oraz żużla odzwierciedlającą warunki eksploatacyjne w kadzi. W warunkach laboratoryjnych można również odtworzyć zjawisko powstawania warstwy odwęglonej przez tlenki żelaza i tlen atmosferyczny. Przeprowadzono badania porównawcze wyrobów MgO-C i AMC w piecu indukcyjnym z pomiarem gradientu temperatury, kontrolując zmiany składu chemicznego żużla. Dla zbadania stopnia zużycia porównywano powierzchnię przekroju wżerów. Badania takie pozwalają na ocenę nowego typu spoiw węglowych i dodatków zwiększających odporność na korozję materiałów MgO-C, wpływając na osadzanie nowych faz w porach podczas penetracji ciekłego żużla. W praktyce przemysłowej na korozję materiałów w strefie żużla należy również brać pod uwagę wpływ takich czynników jak utlenianie się powierzchni materiałów podczas rozgrzewania kadzi, naprężenia powstające w wyniku rozszerzalności cieplnej w warstwie roboczej i intensywna korozja na styku kształtek.
EN
The authors developed a laboratory model of corrosion processes taking into account the quickly progressing saturation of a slag portion and a controlled temperature gradient in the contact layer of the examined samples. Suitable selection of a resonance frequency and metal-coil distance made it possible to determine the metal and slag velocity which resembled operating conditions in a ladle. Also the phenomenon of decarburized layer formation due to iron oxides and atmospheric oxygen may be reconstructed in laboratory conditions. Comparative investigations into MgO-C and AMC with temperature gradient measurements were conducted in an induction furnace while controlling the changes of slag chemical composition. In order to compare the degree of wear, the cross-sectional area of pits was compared. Such investigations allow a new type of carbon binders and additives to be evaluated which increase the corrosive resistance of MgO-C materials, influencing the sedimentation of new phases in pores in the process of liquid slag penetration. In industrial practice, the corrosion of materials in the slag zone is also influenced by such factors as material surface oxidation in the process of ladle heating, stresses due to thermal expansion in the working layer and intense corrosion in the shapes’ contact area.
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