Assessment of improved modal pushover analysis for eccentrically braced frames

This paper concentrates on evaluation of current Pushover Procedures to assess the seismic demands of Eccentrically Braced Frame (EBF). Three 5, 10 and 15 storey EBF frames, designed by Iranian codes, analyzed for five ground motions by MPA, IMPA, and as a proposed method MPA based on Energy-Based capacity curve (briefly E-B.MPA), also story drift of frames were estimated by conventional pushover using two Load distributions of FEMA-356, ELF and uniform patterns. It was considered, the 10 and 15 storey frames have reversal capacity curves, therefore the pushover curve of another story (not roof) was plotted to perform MPA but E-B.MPA was done with no difficulty. Comparing the responses of procedures with the results of Nonlinear Time History Analysis (NTHA) demonstrates that MPA.E-B determines drift demands of models with reversal capacity curves more accurate than other procedures. Moreover there are serious concerns about estimated drift demands of two load patterns

The Effects of Phase Transformation on the Structure and Mechanical Properties of TiSiCN Nanocomposite Coatings Deposited by PECVD Method

In the present study, the effects of phase transformations on the structure and mechanical properties of TiSiCN coatings were investigated. TiSiCN nanocomposite coatings were deposited on AISI H13 hot-work tool steel by a pulsed direct current plasma-enhanced chemical vapor deposition process at 350 or 500 °C, using TiCl4 and SiCl4 as the precursors of Ti and Si, respectively, in a CH4/N2/H2/Ar plasma as the source of carbon and nitrogen and reducing environment. Some samples deposited at 350 °C were subsequently annealed at 500 °C under Ar atmosphere. Super hard self-lubricant TiSiCN coatings, having nanocomposite structure consisting of TiCN nanocrystals and amorphous carbon particles embedded in an amorphous SiCNx matrix, formed through spinodal decomposition in the specimens deposited or annealed at 500 °C. In addition, it was revealed that either uncomplete or relatively coarse phase segregation of titanium compounds was achieved during deposition at 350 °C and 500 °C, respectively. On the contrary, by deposition at 350 °C followed by annealing at 500 °C, a finer structure was obtained with a sensible improvement of the mechanical properties of coatings. Accordingly, the main finding of this work is that significant enhancement in key properties of TiSiCN coatings, such as hardness, adhesion and friction coefficient, can be obtained by deposition at low temperature and subsequent annealing at higher temperature, thanks to the formation of a fine grained nanocomposite structure

Global burden and strength of evidence for 88 risk factors in 204 countries and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

Background: Understanding the health consequences associated with exposure to risk factors is necessary to inform public health policy and practice. To systematically quantify the contributions of risk factor exposures to specific health outcomes, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 aims to provide comprehensive estimates of exposure levels, relative health risks, and attributable burden of disease for 88 risk factors in 204 countries and territories and 811 subnational locations, from 1990 to 2021. Methods: The GBD 2021 risk factor analysis used data from 54 561 total distinct sources to produce epidemiological estimates for 88 risk factors and their associated health outcomes for a total of 631 risk–outcome pairs. Pairs were included on the basis of data-driven determination of a risk–outcome association. Age-sex-location-year-specific estimates were generated at global, regional, and national levels. Our approach followed the comparative risk assessment framework predicated on a causal web of hierarchically organised, potentially combinative, modifiable risks. Relative risks (RRs) of a given outcome occurring as a function of risk factor exposure were estimated separately for each risk–outcome pair, and summary exposure values (SEVs), representing risk-weighted exposure prevalence, and theoretical minimum risk exposure levels (TMRELs) were estimated for each risk factor. These estimates were used to calculate the population attributable fraction (PAF; ie, the proportional change in health risk that would occur if exposure to a risk factor were reduced to the TMREL). The product of PAFs and disease burden associated with a given outcome, measured in disability-adjusted life-years (DALYs), yielded measures of attributable burden (ie, the proportion of total disease burden attributable to a particular risk factor or combination of risk factors). Adjustments for mediation were applied to account for relationships involving risk factors that act indirectly on outcomes via intermediate risks. Attributable burden estimates were stratified by Socio-demographic Index (SDI) quintile and presented as counts, age-standardised rates, and rankings. To complement estimates of RR and attributable burden, newly developed burden of proof risk function (BPRF) methods were applied to yield supplementary, conservative interpretations of risk–outcome associations based on the consistency of underlying evidence, accounting for unexplained heterogeneity between input data from different studies. Estimates reported represent the mean value across 500 draws from the estimate's distribution, with 95% uncertainty intervals (UIs) calculated as the 2·5th and 97·5th percentile values across the draws. Findings: Among the specific risk factors analysed for this study, particulate matter air pollution was the leading contributor to the global disease burden in 2021, contributing 8·0% (95% UI 6·7–9·4) of total DALYs, followed by high systolic blood pressure (SBP; 7·8% [6·4–9·2]), smoking (5·7% [4·7–6·8]), low birthweight and short gestation (5·6% [4·8–6·3]), and high fasting plasma glucose (FPG; 5·4% [4·8–6·0]). For younger demographics (ie, those aged 0–4 years and 5–14 years), risks such as low birthweight and short gestation and unsafe water, sanitation, and handwashing (WaSH) were among the leading risk factors, while for older age groups, metabolic risks such as high SBP, high body-mass index (BMI), high FPG, and high LDL cholesterol had a greater impact. From 2000 to 2021, there was an observable shift in global health challenges, marked by a decline in the number of all-age DALYs broadly attributable to behavioural risks (decrease of 20·7% [13·9–27·7]) and environmental and occupational risks (decrease of 22·0% [15·5–28·8]), coupled with a 49·4% (42·3–56·9) increase in DALYs attributable to metabolic risks, all reflecting ageing populations and changing lifestyles on a global scale. Age-standardised global DALY rates attributable to high BMI and high FPG rose considerably (15·7% [9·9–21·7] for high BMI and 7·9% [3·3–12·9] for high FPG) over this period, with exposure to these risks increasing annually at rates of 1·8% (1·6–1·9) for high BMI and 1·3% (1·1–1·5) for high FPG. By contrast, the global risk-attributable burden and exposure to many other risk factors declined, notably for risks such as child growth failure and unsafe water source, with age-standardised attributable DALYs decreasing by 71·5% (64·4–78·8) for child growth failure and 66·3% (60·2–72·0) for unsafe water source. We separated risk factors into three groups according to trajectory over time: those with a decreasing attributable burden, due largely to declining risk exposure (eg, diet high in trans-fat and household air pollution) but also to proportionally smaller child and youth populations (eg, child and maternal malnutrition); those for which the burden increased moderately in spite of declining risk exposure, due largely to population ageing (eg, smoking); and those for which the burden increased considerably due to both increasing risk exposure and population ageing (eg, ambient particulate matter air pollution, high BMI, high FPG, and high SBP). Interpretation: Substantial progress has been made in reducing the global disease burden attributable to a range of risk factors, particularly those related to maternal and child health, WaSH, and household air pollution. Maintaining efforts to minimise the impact of these risk factors, especially in low SDI locations, is necessary to sustain progress. Successes in moderating the smoking-related burden by reducing risk exposure highlight the need to advance policies that reduce exposure to other leading risk factors such as ambient particulate matter air pollution and high SBP. Troubling increases in high FPG, high BMI, and other risk factors related to obesity and metabolic syndrome indicate an urgent need to identify and implement interventions

Dynamic softening of ferrite during large strain warm deformation of a plain-carbon steel

The evolution of dynamic ferrite softening in a plain-carbon steel was investigated by torsion tests during warm deformation at 810 &deg;C, in the two-phase (ferrite + austenite) region, and strain rate of 0.1 s&minus;1 with different strains up to 50. The warm flow behaviour and ferrite microstructural parameters, such as grain size, misorientation angle across ferrite/ferrite boundaries, and the fraction of high-angle and low-angle grain/subgrain boundaries were quantified using electron back scatter diffraction. The results show that with increasing strain up to not, vert, similar2, the ferrite grain size and fraction of high-angle boundaries rapidly decrease and the fraction of low-angle boundaries increases. However, these parameters remain approximately unchanged with increasing strain from not, vert, similar2 to 50. The dynamic softening mechanism observed during large strain ferritic deformation is explained by dynamic recovery and continuous dynamic recrystallization.<br /

Investigating the formation of intermetallic compounds during friction stir welding of magnesium alloy to aluminum alloy in air and under liquid nitrogen

This research demonstrates the use of submerged friction stir welding under liquid nitrogen as an alternative and improved method for creating fine-grained welds, and hence, to alleviate formation of intermetallic phases. Magnesium alloy and aluminum alloy were joined by friction stir welding in two environments, namely air and liquid nitrogen, with 400 rpm rotation and 50 mm/min travel speed. The temperature profile, microstructure, scanning electron microscope energy dispersive X-ray spectroscopy analysis and hardness were evaluated. In the stir zone of air-welded specimen, formation of brittle intermetallic compounds causes the weld to crack. These phases were formed because of constitutional liquation. The stir zone of under liquid nitrogen-welded specimen showed that formation of intermetallic compounds is suppressed significantly because of lower heat input

Characterization on ferrite microstructure evolution during large strain warm torsion testing of plain low carbon steel

Ferrite grain/subgrain structures evolution during the extended dynamic softening of a plain low carbon steel was investigated throughout the large strain warm deformation by hot torsion. Microstructural analysis with electron back-scattering diffraction (EBSD) scanning electron microscope (FEG/SEM) was carried out on the ferrite microstructural parameters. The results showed that the warm flow stress&ndash;strain curves are similar to those affected only by dynamic softening and an extended warm flow softening is seen during large strain deformation up to 30. Furthermore, with an increase in strain up to ~ vert, similar1 the grain size of ferrite, misorientation angle and fraction of high-angle boundaries gradually decrease and fraction of low-angle boundaries increases. With a further increase in the strain beyond ~, vert, similar2, these parameters remain approximately unchanged. No evidence of discontinuous dynamic recrystallisation involving nucleation and growth of new grains was found within ferrite. Therefore, the dynamic softening mechanism observed during large strain ferritic deformation is explained by continuous dynamic recrystallization (CDRX).<br /

Effect of Feedstock Powder Morphology on Cold-Sprayed Titanium Dioxide Coatings

The properties of cold-sprayed ceramic coatings depend not only on the process parameters but also on the feedstock powder characteristics. To clarify the effect of feedstock powder on cold spraying, two titanium oxide powders were used in this study: (1) nanopowder and (2) agglomerated powder prepared with nanoparticles and polyvinyl alcohol. The cross sections of the deposited coatings were observed by scanning electron microscopy (SEM). The results showed that the agglomerated powder with micrometer particles made of nano-sized particles passes successfully through the bow shock layer and reached the substrate, thus forming a coating. These particles are embedded into the substrate and form a strong interfacial coating/substrate bond. SEM images revealed that the metallic substrate undergoes plastic deformation, providing interlocking with the particles of the powder, and hence, reasonable bonding to the substrate

A comparative study of the mechanical and tribological properties of PECVD single layer and compositionally graded TiSiCN coatings

In this study, TiSiCN coatings, with and without a Ti/TiN/TiCN interlayer, are deposited on tempered and plasma-nitrided H13 hot-working tool steel substrate by pulsed direct current plasma enhanced chemical vapor deposition. The self-lubricant super hard TiSiCN coatings have a nanocomposite structure consisting of an amorphous SiCN matrix embedding TiCN nanocrystals. In the presence of the graded interlayer, coating adhesion improves significantly, as revealed by a 40% increase of the critical load for adhesion failure in scratch testing of the coated samples. The formation of shorter radial cracks around the indentation zone during Rockwell C indentation test reveals that the coating with the graded interlayer has a higher toughness compared to the single layer coating. The wear rate of the graded coating is found to be about three times lower than that of the single layer coating, which can be attributed to the higher hardness, better adhesion to the substrate and higher toughness of the graded coating