Chemistry and radiation in oxy-fuel combustion: A computational fluid dynamics modeling study

In order to investigate the role of combustion chemistry and radiation heat transfer in oxy-fuel combustion modeling, a computational fluid dynamics (CFD) modeling study has been performed for two different oxy-fuel furnaces. One is a lab-scale 0.8 MW oxy-natural gas flame furnace whose detailed in-flame measurement data are available; the other is a conventional 609 MW utility boiler which is assumed to be operating under oxy-fuel combustion condition with dry flue gas recycle. A new model for gaseous radiative properties is developed, validated, and then implemented in the CFD simulations. The CFD results are compared to those based on the widely used model in literature, as well as the in-flame measurement data. The importance and advantage of the new model for gaseous radiative properties have been well demonstrated. Different combustion mechanisms are also implemented and compared in the CFD simulations, from which significant difference in the predicted flame temperature and species is observed. This difference is consistent with those expected from the equilibrium calculation results. As a conclusion, the appropriate combustion mechanisms applicable to oxy-fuel combustion modeling are identified. Among the key issues in combustion modeling, e.g., mixing, radiation and chemistry, this paper derives useful guidelines on radiation and chemistry implementation for reliable CFD analyses of oxy-fuel combustion, particularly for industrial applications.     

Applying industrial ecosystem indicators: case of Pielinen Karelia,Finland

This paper presents an industrial ecological insight into local waste management in Pielinen Karelia, Finland. There local system is experiencing major changes because of tightening EC waste legislation including the directives on waste incineration (2000/76/EC) and landfilling of wastes (1999/31/EC). Small local landfills are closing and most of municipal wastes will be transported 120–180 km to large-scale waste management centre in Kuopio. The paper applies three industrial ecosystem indicators, based on environmental, economic and employment impacts of different waste management technologies. Environmental indicator is CO₂ equivalent emission, economic indicator is based on costs and revenues of waste management, and social (i.e. employment) indicator includes new jobs generated. The results indicate that waste incineration option in forthcoming regional cooperation could create emission savings up to 117–394 kg CO₂ eqv./ton of municipal waste when compared to local landfilling. As economic impacts, new regional cooperation and long-distance transportations will increase the costs from previous 45.6–55.2 €/ton in local landfilling to 97.4 €/ton in regional landfilling and 120.8–126.9 €/ton in regional REF-III incineration. In terms of employment, the new cooperation could create 2–6.5 new jobs. The regional cooperation results to rising operational costs but avoids investments to new local infrastructure. It also creates significant emission savings, maintains current employment in waste handling and creates new jobs in long-distance transportation.

Smoking mothers and snuffing fathers: behavioural influences on youth tobacco use in a Swedish cohort

Objective: To analyse the influences of parental use of cigarettes and snus (the Swedish variety of smokeless tobacco) on offspring's behaviour.     

Cloning, pharmacological characterization, and expression analysis of Atlantic salmon (Salmo salar L.) nuclear progesterone receptor

To better understand the role(s) of progestogens during early stages of spermatogenesis, we carried out studies on the nuclear progesterone receptor (Pgr) of the Atlantic salmon. Its open-reading frame shows the highest similarity with other piscine Pgr proteins. When expressed in mammalian cells, salmon Pgr exhibited progestogen-specific, dose-dependent induction of reporter gene expression, with 17α,20β-dihydroxy-4-pregnen-3-one (DHP) showing the highest potency. We then analyzed testicular pgr mRNA and DHP plasma levels in animals during the onset of spermatogenesis, which were exposed to natural light or to constant light, to induce significant differences in testis growth. Grouping of the animals according to their progress through spermatogenesis showed that testicular pgr mRNA levels as well as DHP plasma levels first increased when germ cells had reached the stage of late type B spermatogonia and further increased when entered meiosis, i.e. when spermatocytes were present. However, in situ hybridization studies revealed that pgr mRNA expression was restricted to Sertoli cells, with a strong signal in Sertoli cells contacting type A/early type B spermatogonia, while Sertoli cells contacting larger germ cell clones with further differentiated stages (e.g. late type B spermatogonia) were less intensely/not stained. We conclude that the increase in pgr mRNA levels per pair of testis reflects, at least in part, the increased number of Sertoli cells enveloping type A and early type B spermatogonia. We propose that Sertoli cell-expressed Pgr may mediate DHP-stimulated early steps in spermatogenesis in Atlantic salmon, such as an increase in the number of new spermatogonial cysts.     

基于FLUX 2D的大型同步发电机在额定运行下定子绕组匝间短路故障特性研究

该文采用单一绕组分析和有限元分析相结合的方法,研究大型同步发电机在额定运行方式下定子绕组匝间短路故障特性。该方法同样适用于确定故障条件下的电流和转矩。对于内部故障情况的电磁瞬态仿真必须考虑到一些特殊措施,如单一绕组和电网之间正确的连接对于模拟内部故障是相当关键的。以往的结果表明,在内部磁场非对称的情况下,基于等效电路的经典算法是不适用的。该文通过对汽轮发电机匝间短路故障进行系统的研究,表明:其短路电流、相电流、转矩和径向力与短路的位置及匝数紧密相关。在一些短路情况下,发电机将产生很大的局部电流,该局部电流对同步发电机的影响甚至超过外部故障。此外,很大的径向力作用在转子上可能对整个转轴产生极大的危害。     

Distribution of (210)Pb and (210)Po in boreal forest soil

Vertical distribution and activity contents of ²¹⁰Pb and ²¹⁰Po were investigated in forest soils of Scots pine-dominated (Pinus sylvestris L.) stands from seven different locations in Finland. The mean total inventory in the soil profile, up to 20 cm, of ²¹⁰Pb was 4.0 kBq m^− 2 (range 3.1-5.0 kBq m^− 2) and ²¹⁰Po 5.5 kBq m^− 2 (range 4.0-7.4 kBq m^− 2), the organic soil layer containing 45% of the total inventory of both nuclides. In both the organic and the mineral layers the ²¹⁰Po/²¹⁰Pb ratio was close to unity indicating a radioactive equilibrium between them. In the litter layer there was, however, a clear excess of ²¹⁰Po suggesting that polonium is recycled via root uptake from the root zone to the ground surface. The activity concentration (Bq kg^− 1) of ²¹⁰Pb clearly correlated with organic matter and the Fe, Al and Mn concentrations in soil indicating that radioactive lead is associated both with humic substances and the oxides of iron, aluminium and manganese. Radioactive lead was also seen to follow the behavior of stable lead. No systematic correlation between polonium and soil properties was seen.