Bottleneck Management through Strategic Sequencing in Smart Manufacturing Systems

Nowadays, industries put a significant emphasis on finding the optimum order for carrying out jobs in sequence. This is a crucial element in determining net productivity. Depending on the demand criterion, all production systems, including flexible manufacturing systems, follow a predefined sequence of job-based machine operations. The complexity of the problem increases with increasing machines and jobs to sequence, demanding the use of an appropriate sequencing technique. The major contribution of this work is to modify an existing algorithm with a very unusual machine setup and find the optimal sequence which will really minimize the makespan. This custom machine setup completes all tasks by maintaining precedence and satisfying all other constraints. This thesis concentrates on identifying the most effective technique of sequencing which will be validated in a lab environment and a simulated environment. It illustrates some of the key methods of addressing a circular non permutation flow shop sequencing problem with some additional constraints. Additionally, comparisons among the various heuristics algorithms are presented based on different sequencing criteria. The optimum sequence is provided as an input to a real-life machine set up and a simulated environment for selecting the best performing algorithm which is the basic goal of this research. To achieve this goal, at first, a code using python programming language was generated to find an optimum sequence. By analyzing the results, the makespan is increasing with the number of jobs but additional pallet constraint shows, adding more pallets will help to reduce makespan for both flow shops and job shops. Though the sequence obtained from both algorithms is different, for flow shops the makespan remains same for both cases but in the job shop scenario Nawaz, Enscore and Ham (NEH) algorithms always perform better than Campbell Dudek Smith (CDS) algorithms. For job shops with different combinations the makespan decreases mostly for maximum percentage of easy category jobs combined with equal percentage of medium and complex category jobs

A global perspective of the current state of heavy metals contamination in road dust

16 Heavy metals are persistent and bio-accumulative, and pose potential risk to human health and 17 ecosystem. We reviewed the current state of heavy metals contamination, the ecotoxicological 18 and human health risk of heavy metals reported in urban road dust from various cities in different 19 continents (Asia, Europe, Africa, America, and Australia). We compared and synthesized the 20 findings on the methods related to sample collection, extraction, analytical tools of heavy metals, 21 their concentrations, level of contamination, ecological risk, non-carcinogenic risk, and 22 carcinogenic risk in road dust. Concentrations of Pb, Zn, Cu, Ni, Cd, Cr, Mn, and Fe were found 23 to be higher than their background values in soil. As expected, the contamination levels of the 24 heavy metals varied extensively among cities, countries, continents, and periods. A high level of 25 contamination is observed for Pb and Cd in road dust due to operating leaded gasoline and the old 26 vehicle population. The highest Zn contamination was observed from road dust in Europe, 27 followed by Asia, Africa, Australia, and America (North America and South America). Cu 28 contamination and the pollution load index (PLI) is found to be the highest in Europe and lowest 29 in Africa, with in-between values of PLI in American and African cities. The potential ecological 30 risk on different continents was observed highest in Asia, followed by Europe, Australia, America, 31 and Africa. A comparative assessment of non-carcinogenic risk for children indicated that 32 Australia is a most susceptible country due to high heavy metals exposure in road dust, followed 33 by Asia. However, there is no susceptible risk in European, African and American cities. We did 34 not observe any potential risk to adults due to non-carcinogenic metals. Carcinogenic risk to all 35 age groups was within the threshold limit range for all the regions worldwide. 3

Reconciliation of energy use disparities in brick production in India

Abstract Energy conservation in brick production is crucial to achieving net-zero carbon emissions from the building sector, especially in countries with major expansions in the built environment. However, widely disparate energy consumption estimates impede benchmarking its importance relative to the steel and cement industries. Here we modelled Indian brick production and its regional energy consumption by combining a nationwide questionnaire survey on feedstock, process variables and practices with remote sensing data on kiln enumeration. We found a large underreporting in current official estimates of energy consumption, with actual energy consumption comparable to that in the steel and cement industries in the country. With a total estimated production of 233 ± 15 billion bricks per year, the brick industry consumes 990 ± 125 PJ yr −1 of energy, 35 ± 6 Mt yr −1 coal and 25 ± 6 Mt yr −1 biomass. The main drivers of energy consumption for brick production are the kiln technology, the production capacity and the fuel mix used. The results suggest that improving operating practices would be a first step in making brick production more energy efficient