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Aeronautics
Published in Doramas Jorge-Calderón, Aviation Investment, 2020
Upfront, non-recurring capital expenditure would be EUR10bn, independent of the number of S2 aircraft eventually sold. The private sector promoting the aircraft would launch the project only if it yields a return of 15 per cent on invested capital over a 20 year economic life of the project. There needs to be an estimate of what this return implies for aircraft price for different amounts of aircraft sold. A detailed calculation would need to simulate the timing of such sales. Here a simplified ‘back of an envelope’ calculation is followed. It converts the EUR10bn capital investment into a 20 year annuity yielding 15 per cent, implying an annual annuity payment of around EUR1.6bn. Total revenues to the aircraft producers over the 20-year life of the project would then need to be EUR32bn (=EUR1.6bnx × 20), to cover the non-recurring capital expenditure alone. This is included in row 7 as capital cost.
Implementing Project Portfolio Management: Lessons Learned from Implementations
Published in Jamal Moustafaev, Project Portfolio Management in Theory and Practice, 2016
Here is an example of a “back of the envelope” calculation of total project resources bucket at a company. Imagine that there are 250 employees working at the head office. It has been estimated via survey or questionnaires that approximately 30% of their time is spent on the project work and 70% on business as usual, that is, normal daily nonproject tasks. Based on that information, we can assess the size of the total project resource bucket at the company: Total number of people at the head office = 250 peopleTotal number of working months in a year = 10 minus 2 months for vacation, holidays, and sick daysPercentage of time spent on projects = 30% (estimated based on surveys)
What instead of oil?
Published in Rauli Partanen, Harri Paloheimo, Heikki Waris, The World After Cheap Oil, 2014
Rauli Partanen, Harri Paloheimo, Heikki Waris
What do these numbers mean? The EU uses around 13 mbpd of oil. As a “back of the envelope”calculation, replacing this oil with bio-oil is a daunting task. It would require around 2,200 such biorefineries, which cost 0.5 billion apiece. The refineries would require 880 TWh of electricity per year, which equals the combined electricity consumption of Germany and the UK, or around a quarter of the total EU electricity consumption.68 The wood used as the main feedstock amounts to 4,000 million cubic meters annually. This is more than 6 times the annual growth of forests in Europe, and more than 10 times the current annual logging. The forests of Europe would be gone in a mere 6 years,69 and the rather meager 1.3 percent slice that forestry-based activities contribute to European GDP would grow substantially, at least for a few years.70 Of course this is only theoretical. On a more practical note, there have been fears that the price of wood that can also be used in paper production would increase with any large-scale liquefaction projects.
The impact of future atmospheric circulation changes over the Euro-Atlantic sector on urban PM2.5 concentrations
Published in Tellus B: Chemical and Physical Meteorology, 2018
Gabriele Messori, Dave van Wees, Francesco S.R. Pausata, Juan C. Acosta Navarro, Abdel Hannachi, Frank J. Dentener
In the MFR scenario, the IT-1 annual target is never exceeded and the daily target is never exceeded for more than 5 days a year in any urban area in Europe (Figs. 12a, c). Below 40° N, dust intrusions from the Sahara lead to some exceedances. However, we note that the representation of dust in our simulations is highly simplified and subject to significant uncertainty. An MFR scenario would therefore be compatible with the IT-1 levels across the continent, even though we note that it is unlikely for these limits to remain unchanged in the coming decades. Under MFR, many cities in Northern Europe also meet the daily and annual AQG limits, while most areas in the Mediterranean and Central/Eastern Europe display exceedances for 25–150 days every year and for more than 20 of the 30 years considered (Figs. 12b, d). A comparison of Fig. 11 with Fig. 12 shows a clear shift in the regions with the most exceedances. In the control case, Central-Eastern Europe is the region displaying the most severe PM2.5 pollution. Under MFR, the most frequent AQG exceedances are instead seen over Central Europe and the Mediterranean. Over the latter regions, PM2.5 concentrations therefore remain above safe levels for human health even assuming a maximum feasible reduction scenario. For the current pollutant regulations (e.g. PM10), the EU allows a certain number of exceedances of the daily limits every year, while no exceedances are permitted for the yearly limits. A back-of-the-envelope calculation suggests that, fixing the variability in PM2.5 concentrations at MFR levels, the mean concentrations would need to drop by an additional 5 µg/m3 beyond the maximum feasible reduction in order to virtually eliminate (<1% of years and gridpoints) exceedances of the AQG yearly limit over Central and Southern Europe.
Letter to the editor
Published in Journal of the Air & Waste Management Association, 2020
Michael Brody, Alexander Golub
To summarize: This letter in no way intends to challenge the GEMM model. Given the list of authors, it may eventually become standard of practice, at least when the appropriate data are availableGiven the mobility of part of the Kazakh population today to bigger cities, especially to Nur-Sultan, age-and disease-specific diseases have to be used very carefully, even assuming they are accurately recordedEnvironmental health specialists at the National Medical University did not use the official health statistics at face valueIt would be helpful if the authors had provided the TSP data they received and then the PM2.5 data they calculated, and to see how they implemented the GEMM model and then to compare it to results from the current WHO GBD model.Had they read our article, which was a similar effort, they might have carried out a more thoughtful conversion of TSP to both PM10 and PM2.5. Based on the actual monitoring data now available, our conversion method seems more accurate.Since monitoring data started becoming available in early 2018, and this paper was only first published in September 2019, the authors could have checked their PM2.5 estimations for Nur-Sultan against these measured concentrations.Using their results, we did a quick back of the envelope calculation of individual risk, and it would be approximately 0.8*10−2 (and 1.2*10−2 for the urban population) which is extremely high.
TRACE Analysis of a Loss of Alternating-Current Power Without Rod Insertion for the NuScale Power Module—II: Sensitivity to Varying Initial Temperature
Published in Nuclear Technology, 2021
The total SG heat transfer removal is approximated using a simple, back-of-the-envelope calculation to determine an adjustment factor to degrade the SG heat transfer. For the purpose of determining an adjustment factor, a simplified calculation is justified as long as the subsequent sensitivity studies explore a range around the result and confirm that acceptability of the approach.