In general, the mixing the reactants is very important to the process and the rate of combustion of each fuel, especially low-ranked coals with low reactivity. The appropriate excess air coefficient for combustion and the position and mode of supply of individual portions (air sta- ging) of the total air in the furnace are one of the key influ- encing factors for the mixing, respectively the efficiency of the combustion process, and the level of emissions. Today, the air staging (primary, secondary, tertiary and over fire air-OFA) is an indispensable process in the design of new industrial and energy boilers. Also, this measures are used for the reconstru- ction of existing furnace of large boilers. The implementation of this primary measure in the furnace does not require signi- ficant financial resources - the costs of investing in the intro- duction of air staging supply for combustion in the furnace are very low in relation to the multiple positive effects and bene- fits of such a system, especially a lower NOx emissions. However, the first condition for the correct and reliable design of the air staging system in the furnace is the choice of the optimal position for the supply OFA air. Determination of this position on the furnace depends on several factors, primarily the type and characteristics of the fuel, grinding quality, co- mbustion technology, furnace structure, type, number and arra- ngement of burners. On this topic, the Faculty of Mechanical Engineering of the University of Sarajevo, in the Laboratory for Coal and Biomass Combustion, conducted extensive rese- arch on the pulverized combustion of coal blends of the Ce- ntral Bosnia Mining Basin, including co-firing of these coals with waste wood biomass (beech and spruce sawdust). Here is presented some of the results of those NOx emission studies for different fuels and combustion temperatures, depending on the mode of supply and the positions of the combustion air supply in the boiler furnace.

The aim of this paper is to highlight the role and level of vitamin D in chronic diseases at the primary level

Human migration is an outstanding example of a policy domain in which the links between European countries and their surroundings are revealed. The policy domains of asylum, migration and border control touch on international mobility, the protection of fundamental human rights, and international security all around Europe and within it. They also provoke intense debate among populations.

The previous chapter described how globalisation, the erosion of embedded liberalism and social protection, and pressure on mutual solidarity between Member States have led to growing frictions in the European Union. These frictions have usually had a combination of causes: external events, internal choices, or the unforeseen consequences of compromises that turned out better for one country or one segment of the population than for another.

Since the early years of the common market, the Community legal order has focused on removing obstacles to the free movement of goods, persons, services and capital; in other words, on creating a single market. Social protection remained in place in national legislation; harmonisation was sought where politically feasible, but ‘Europeanisation’ has remained limited in this domain. Free competition was promoted through a European-level anti-trust policy and by counteracting preferential treatment by national governments. As a Member State of the European Union, the Netherlands is part of an internal and external economy of unprecedented power, with more than half a billion consumers and a combined Gross Domestic Product (GDP) of 14,714 billion euros (2015), the largest GDP in the world. Two thirds of the EU’s trade in goods takes place between EU countries, with a volume of 3070 billion euros (2015). Approximately 72% of Dutch goods exports (measured in terms of their value) go to EU countries, and more than half of its imports come from EU countries (2015). With the removal of barriers as the starting point, the Netherlands, like its neighbouring countries, is closely intertwined with its European biotope. Dutch legislation is embedded in European legislation in almost every area, and in fact it must be, because differences would be susceptible to exploitation in the single market. Even technical requirements for appliances must not differ too much from country to country, as they would otherwise create an obstacle to European trade or give one or other country an undesirable competitive advantage. Since the reforms of recent decades, virtually all relevant legislation is the result of joint decision-making by the European Parliament and the Council of the European Union, at the initiative of the European Commission. The Member States are represented in the Council by a minister; decisions are taken by qualified majority, which means that for a decision to pass, at least 55% of the Member States, representing at least 65% of the population, must be in favour of it. The weekly

The internal market, which encompasses the free movement of goods, persons, services and capital, is at the heart of European cooperation. The Treaty on the Functioning of the European Union (TFEU) prohibits Member States, and in some cases private organisations, from introducing measures that impede free movement. In addition, there are provisions in the Treaty that prohibit companies from obstructing competition in the internal market.