19 research outputs found
OPTIMIZATION OF CYCLE TIME IN HYUNDAI MOTORS INDIA LTD
This paper sheds light on the application of quality control tools to reduce Cycle time (including Weld time and Squeeze time). Successive use of these tools identifies and addresses the weakness and leads to improved processes. These tools address the problems in logical and sequential manners which are easy to observe and interpret the result. The main gist of this paper is to achieve the target cycle time of body build line. Cycle time includes process time, during which a unit is acted upon to bring it closer to an output. Every production line always has a target cycle time. With the collected data it was found that cycle time was higher than the target cycle time, so it needed to be optimized. There are lots of factors which are to be eliminated in order to achieve the target cycle time. The root cause of the factors affecting the target cycle time was observed using quality improvement tools known as the Ishikawa diagram or the ‘Fish Bone Diagram’
PERFORMANCE ASSESSMENT AND STATISTICAL ANALYSIS OF CONCRETE MIXES INCORPORATING GLASS WASTE POWDER
Worldwide, annual glass waste production surpasses 200 million tonnes, urging exploration of sustainable reuse avenues. This study evaluates the incorporation of waste glass powder (WGP) into concrete as a partial replacement for fine aggregate. Thirty concrete mixes, varying water-cement ratios and WGP levels, underwent comprehensive analysis. Findings reveal that as WGP percentage in sand increases, the slump of concrete rises marginally until reaching maximum glass powder replacement, with workability remaining within the 50 to 100 mm range. At a 10% replacement level, early and later age strength minimally impacts compressive strength. WGP's workability and strength hinge on particle geometry, indicating increased concrete strength when mixed with WGP featuring higher surface area and improved cement paste bonding. To enhance solid waste management, conserve sand, and bolster sustainability, WGP can replace up to 10% of sand weight in concrete at lower water-cement ratios. Positive correlation exists between slump and WGP percentage replaced. Both water-cement ratio and replacement amount significantly influence compressive strength, as confirmed by ANOVA. However, long-term mechanical strength and durability research is essential before recommending WGP for environmentally friendly and sustainable concrete applications, promising increased understanding through additional data collection and analysis
Clinical profile of patients with prosthetic heart valve thrombosis undergoing fibrinolytic therapy and NYHA class as a predictor of outcome
Background: Prosthetic heart valve thrombosis (PHVT) is a potentially fatal complication of heart valve replacement with mechanical prostheses mainly due to thrombosis.Aim: The study aimed to evaluate the clinical profile of the patients presenting with PHVT undergoing fibrinolytic therapy and analyzing patients with respect to New York Heart Association (NYHA) functional class on presentation and its association with outcome of fibrinolytic therapy.Settings & design: This was prospective, observational study conducted from June, 2016 to April, 2017. Total 133 patients with prosthetic heart valve thrombosis were included. Materials and methods: Routine blood investigations included complete hemogram, liver and renal function tests. Prothrombin time with INR was done on admission. The diagnosis of PHVT was assessed by fluoroscopy and/or echocardiography (transthoracic/transesophageal). Follow-up at 6 months was scheduled for all patients.Statistical analysis: Parametric values between two groups were performed using the independent sample t-test or chi-square test, as appropriate. Univariate and multivariate logistic regression was used to find out factors associated with outcome.Results: All patients received fibrinolytic therapy in which 108 (81.2%) were treated with streptokinase and 25 (18.8%) were treated with urokinase. On presentation, 48.9% patients were in NYHA class III, 41.4% in NYHA class IV and 9.77% in NYHA class II. Fibrinolytic therapy was successful in 105 patients (78.9%) and it failed in 28 patients (21.1%). Mortality in NYHA class II was 0%, NYHA class III was 4.6% and in NYHA class IV was 23.6%. During 6 months follow up prosthetic heart valve thrombosis recurred in 12 (11.43%) patients.Conclusion: From our single centre experience, fibrinolytic therapy is fairly effective first line therapy for prosthetic heart valve thrombosis and NYHA functional class on presentation can predict the outcome of fibrinolytic therapy
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Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021
BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation
Investigation of mixing in gravity currents using high-resolution molecular tagging techniques
© 2020 Tanmay AgrawalGravity currents are horizontal flows of fluid of a higher density into an ambient fluid of
slightly lower density. They occur frequently in the atmosphere as sea-breeze fronts, thunderstorm outflows, katabatic flows etc., and are also encountered in industrial applications. The initial density difference between the two fluids can either be due to the presence of a salt or a temperature difference. While a majority of the studies employ a salinity based stratification, this work focuses on the flow dynamics of a gravity current generated as a result of an initial temperature difference.
In the laboratory environment, a gravity current can be produced using a lock-exchange experiment in which the two fluids, initially at rest, are separated by a vertical barrier (or lock gate). At time = 0, a rapid removal of the lock gate results in the formation of a gravity current. The present gravity currents were produced in a Perspex tank of 2.0 m x 0.2 m x 0.2 m where the lock was located mid-way. The present flows were first visualized by mixing a dye in the heavier (cold) side to evaluate the bulk properties of the flow e.g. Froude number, . Subsequently, simultaneous measurements of streamwise velocity and temperature field were conducted using the single-component molecular tagging velocimetry (1c-MTV) and molecular tagging thermometry (MTT) respectively. These experiments were focused at the interface between the hot and cold fluid to estimate the resultant mixing across the interface. The measurements were acquired using a 1024 x 1024 pixel Princeton Instruments PI: MAX4 camera and were shown to resolve the Kolmogorov (velocity) and Batchelor (scalar) length scales. To the author's knowledge, to date no previous experimental study has documented lock-exchange mixing at this level of resolution.
The obtained density (temperature) distribution allows an estimation of the background potential energy of the flow which was used to quantify the diapycnal mixing. Specifically, mixing is attributed to the irreversible changes in fluid properties associated with fluid motions [1] and therefore differentiated from buoyancy induced reversible stirring. These measurements yield a mixing efficiency of 0.13 for the Reynolds number range considered (). Flow analysis revealed that the locally high values of mixing efficiency occur \textit{after} the occurrence of certain dissipative stirring events in the flow. These events, largely associated with vortical overturns, are commonly observed at the interface between the two fluids and are shown to lead the locally efficient mixing
Clustering What Matters: Optimal Approximation for Clustering with Outliers
Clustering with outliers is one of the most fundamental problems in Computer Science. Given a set X of n points and two numbers k and m, the clustering with outliers aims to exclude m points from X, and partition the remaining points into k clusters that minimizes a certain cost function. In this paper, we give a general approach for solving clustering with outliers, which results in a fixed-parameter tractable (FPT) algorithm in k and m (i.e., an algorithm with running time of the form f(k, m) * poly(n) for some function f), that almost matches the approximation ratio for its outlier-free counterpart.
As a corollary, we obtain FPT approximation algorithms with optimal approximation ratios for k-Median and k-Means with outliers in general and Euclidean metrics. We also exhibit more applications of our approach to other variants of the problem that impose additional constraints on the clustering, such as fairness or matroid constraints
Improvement in sealing effectiveness of air curtains using positive buoyancy
Air curtains are commonly employed in building applications to facilitate
aerodynamic sealing against the exchange flow that occurs through an open
doorway due to the density differences owing to buoyancy. Such situations often
prevail due to temperature gradients across a doorway of an air-conditioned
building, e.g., during the summer season in an Indian subcontinental situation.
In the present study, we numerically investigate the performance of `positively
buoyant' air curtains. In such installations, the density of the jet fluid is
larger than the density of the fluid contained within the building space. Using
the two-dimensional Reynolds-averaged Navier-Stokes (2D RANS) formulation, we
compute the temperature distribution in the flow domain and estimate the
associated sealing effectiveness for various values of positive jet buoyancy
and operating velocities of the air curtain. These estimates of sealing
effectiveness are compared with that of a neutrally buoyant air curtain to
assess the influence of positive buoyancy. We report an increase in sealing
effectiveness of up to 10%, whereas its peak value improves by about 5%.Comment: Fluid Mechanics and Fluid Power Conference 202