Secondary atomization of coal-water fuels for gas turbine applications

The main research objective is to determine the effect of coal-water fuel (CWF) treatment on atomization quality when applied to an ultrafine coal water fuel (solids loading - 50%) and at elevated pressures. The fuel treatment techniques are expected to produce secondary atomization, i.e., disruptive shattering of CWF droplets subsequent to their leaving the atomizing nozzle. Upon combustion, the finer fuel droplets would then yield better burnout and finer fly ash size distribution, which in turn could reduce problems of turbine blade erosion. The parallel objective was to present quantitative information on the spray characteristics of CWF (average droplet size and spray shape and angle) with and without fuel treatment for purposes of application to the design of CWF-burning gas turbine combustors. The experiments include laser diffraction droplet size measurements and high speed photographic studies of CWF sprays in the MIT Spray Test Facility to determine mean droplet size (mass median diameter), droplet size distribution, and spray shape and angle. For the spray tests at elevated pressures, pressure vessels were constructed and installed in the spray test rig. For support of data analyses, a capillary tube viscometer was used to measure the CWF viscosity at the high shear rate that occurs in an atomizer (> 104 sec' ). A semi-empirical relationship was developed giving the CWF spray droplet size as a function of the characteristic dimensionless parameters of twin-fluid atomization, including the Weber number, the Reynolds number, and the air-to-fuel mass flow ratio. The correlation was tested experimentally and good agreement was found between calculated and measured drop sizes when the high shear viscosity of the CWF was used in the semi-empirical equation. Water and CWF spray tests at elevated pressure were made. Average droplet sizes measured as a function of atomizing air-to-fuel ratios (AFRs) at various chamber pressures show that the droplet mass median diameter (MMD) decreases with increasing AFR at a given chamber pressure and increases with increasing chamber pressure at a given AFR. In particular, the results show that droplet sizes of CWF sprays decrease with increasing chamber pressure if the atomizing air velocity is held constant. Of the fuel treatment techniques investigated, the heating of CWF (flash-atomization) was found to be very effective in reducing droplet size, not only at atmospheric pressure but also at elevated pressure. Secondary atomization by C02 absorption (used in a previous study) had given favorable results on CWF combustion, but in this present case this fuel treatment did not seem to have any observable effect on the drop size distribution of the CWF spray at room temperature. The spray angle was observed to reduce with increasing chamber pressure for given atomizing conditions (AFR, fuel flow rate, fuel temperature). The decreasing entrainment rate per unit length of spray with increasing chamber pressure was mainly responsible for the reduction of the spray angle. The heating of the CWF increased the spray angle, both at atmospheric and elevated pressures. A model was developed to predict spray angle change for the effects of the flash-atomization as a function of AFR, fuel flow rate, and the superheat of the water

Should I stay or should I go? What we can learn from working patterns of Central and Eastern European labour migrants about the nature of present-day migration.

In this paper, we examine the extent to which the employment histories of Central and Eastern EU (CEE) labour migrants exhibit patterns of temporary, circular or settlement migration. We expect to find these diverse and changeable patterns following the phenomenon of ‘New European Migration’. By distinguishing between working patterns we are able to describe actual migration behaviour to the destination country more accurately. We use wage data to track a cohort of all employees who worked in the Netherlands in June 2010, for a period of five years. Our findings show that the majority of CEE labour migrants stopped working as employees in the Netherlands within five years, mostly after an uninterrupted single period of employment. In addition, a third of CEE labour migrants engage in settlement migration, working continuously in the Netherlands for a long period. Only a very small proportion can be considered as circular migrants. This contradicts our expectations regarding New European Migration, that there would be fewer labour migrants with uninterrupted periods of work and more labour migrants working for shorter periods

Explaining differences in unemployment benefit takeup between labour migrants and Dutch native workers

The large increase in Eastern European migrants entering the Dutch labour market has led to concerns about their potential claim on Dutch unemployment benefits. We use a decomposition analysis to investigate differences in uptake of unemployment benefits between migrants and native Dutch employees by analysing register data for all employees in the Netherlands in 2015. The results show that Eastern European migrants, similar to other migrants, receive unemployment benefit more often than native Dutch employees. This difference can be largely ascribed to job characteristics. The inclusion of unemployment risk in the analysis reveals that non-working migrants are much less likely to receive unemployment benefits than Dutch natives

Analytically tractable climate-carbon cycle feedbacks under 21st century anthropogenic forcing

Changes to climate-carbon cycle feedbacks may significantly affect the Earth System’s response to greenhouse gas emissions. These feedbacks are usually analysed from numerical output of complex and arguably opaque Earth System Models (ESMs). Here, we construct a stylized global climate-carbon cycle model, test its output against complex ESMs, and investigate the strengths of its climate-carbon cycle feedbacks analytically. The analytical expressions we obtain aid understanding of carbon-cycle feedbacks and the operation of the carbon cycle. We use our results to analytically study the relative strengths of different climate-carbon cycle feedbacks and how they may change in the future, as well as to compare different feedback formalisms. Simple models such as that developed here also provide "workbenches" for simple but mechanistically based explorations of Earth system processes, such as interactions and feedbacks between the Planetary Boundaries, that are currently too uncertain to be included in complex ESMs

Major Differences in Diet across Three Linguistic Regions of Switzerland: Results from the First National Nutrition Survey menuCH.

Switzerland is a multilingual country located between Germany, France and Italy, which differ by dietary habits and related outcomes. We explored differences in food consumption as well as compliance to the Swiss food-based dietary guidelines (FBDG) across the German-, French-, and Italian-speaking regions. The 2014-2015 nationwide cross-sectional survey was conducted among a stratified random sample of 2057 adults aged 18 to 75 years. Trained dietitians assessed food consumption via two non-consecutive 24-h dietary recalls using the international validated software GloboDiet <sup>®</sup> . Recorded foods and beverages were classified into six groups and 31 subgroups relevant for assessing compliance to the FBDG (Swiss Food Pyramid). Usual daily intake distributions were modelled and weighted for sampling design, non-response, weekdays and season. Participation rate was 38%. Significant differences across regions were observed in 18 of 31 food subgroups ( <i>p</i> ≤ 0.01). Weighted mean daily intakes in the German-, French- and Italian-speaking regions were, respectively, 245 g, 155 g, 140 g for soft drinks, 273 g, 214 g, 135 g for coffee, 127 g, 72 g, 109 g for milk, 32 g, 45 g, 43 g for red meat, 18 g, 29 g, 34 g for fish/seafood, 8.1 g, 6.4 g, 3.7 g for butter, and 206 g, 214 g, 168 g for vegetables. The seven FBDGs were followed by <1% of the population. Four in 10 participants met ≥3 FBDG. Eighteen percent of participants ate ≥5 portions of fruit and vegetables a day, without regional differences. Food consumption substantially differed across the three linguistic regions of Switzerland. Adherence to FBDG was uniformly low. This highlights the potential influence of culture on diet. Nutritional education along with public health interventions are needed and may be most efficient if regionally targeted

The Magnetic Sun: Reversals and Long-Term Variations

A didactic introduction to current thinking on some aspects of the solar dynamo is given for geophysicists and planetary scientists.Comment: 17 pages, 9 figures; Space Science Rev., in pres

False Panama disorder on banana

Musa disease fact sheet on false panama disorder : symptoms, incidence, causes and recommendation

Scoping review : intergenerational resource transfer and possible enabling factors

We explore the intergenerational pattern of resource transfer and possible associated factors. A scoping review was conducted of quantitative, peer-reviewed, English-language studies related to intergenerational transfer or interaction. We searched AgeLine, PsycINFO, Social Work Abstracts, and Sociological Abstracts for articles published between Jane 2008 and December 2018. Seventy-five studies from 25 countries met the inclusion criteria. The scoping review categorised resource transfers into three types: financial, instrumental, and emotional support. Using an intergenerational solidarity framework, factors associated with intergenerational transfer were placed in four categories: (1) demographic factors (e.g., age, gender, marital status, education, and ethno-cultural background); (2) needs and opportunities factors, including health, financial resources, and employment status; (3) family structures, namely, family composition, family relationship, and earlier family events; and (4) cultural-contextual structures, including state policies and social norms. Those factors were connected to the direction of resource transfer between generations. Downward transfers from senior to junior generations occur more frequently than upward transfers in many developed countries. Women dominate instrumental transfers, perhaps influenced by traditional gender roles. Overall, the pattern of resource transfer between generations is shown, and the impact of social norms and social policy on intergenerational transfers is highlighted. Policymakers should recognise the complicated interplay of each factor with different cultural contexts. The findings could inform policies that strengthen intergenerational solidarity and support.</jats:p

Potential feedbacks between loss of biosphere integrity and climate change

Individual organisms on land and in the ocean sequester massive amounts of the carbon emitted into the atmosphere by humans. Yet the role of ecosystems as a whole in modulating this uptake of carbon is less clear. Here, we study several different mechanisms by which climate change and ecosystems could interact. We show that climate change could cause changes in ecosystems that reduce their capacity to take up carbon, further accelerating climate change. More research on – and better governance of – interactions between climate change and ecosystems is urgently required