Poincar\'e dualization and formal domination

We consider the question of whether formality of the domain of a non-zero degree map of closed manifolds implies formality of the target. Though there are various situations where this is indeed the case, we show the answer is negative in general, with a counterexample given by a non-zero degree map from a formal manifold to one that carries a non-vanishing quadruple Massey product. This violates a general heuristic that the domain of a non-zero degree map should be more complicated than its target. For the construction of the counterexample we introduce a method to turn a cdga into one that satisfies Poincar\'e duality, which is natural in certain situations.Comment: 15 pages, comments very welcom

Uticaj kalcizacije i đubrenja na prinos i iskorišćavanje azota i fosfora biljkama ječma na zemljištu tipa pseudoglej

This paper presents the results of studying the influence of liming and fertilization on yield and utilization of nitrogen and phosphorus in tested genotypes of winter barley grown on soil (type pseudogley) with low pH values. During the three-year long investigation was carried out on the field of Agricultural-chemical school "Dr. George Radic" at the place Kraljevo. The results indicated that the highest effect to yield and coefficient of utilization of N and P2O5 were obtained by application fertilizer prepared by use of NPK, lime and manure (N- 80 kg ha-1, P2O5 -100 kg ha-1, K2O-80 kg ha-1 + CaCO3-5000 kg ha-1 + manure – 20000kg ha- 1). On the base of studied parameters the barley cultivar NS565 was more tolerant to adverse chemical soil characteristics (low pH, low P2O5 content and a high content of mobile Al) and can be recommended as a suitable genotype for barley production on acid soils, especialy after liming of soil.U radu su prikazani rezultati proučavanja uticaja kalcizacije i đubrenja na prinos i iskorišćavanje azota i fosfora ispitivanim genotipovima ozimog ječma na zemljištu niske pH vrednosti tipa pseudoglej. Trogodišnja istraživanja su izvedena u lokalitetu Kraljeva na imanju Srednje poljoprivredno-hemijske škole "dr Đorđe Radić". Dobijeni rezultati su pokazali da je najveći ekekat na prinos i koeficijent iskorišćavanja N i P2O5 iz đubriva ostvaren kombinovanom upotrebom NPK, krečnog i stajskog đubriva (80 kg Nha-1, 100 kg P2O5ha-1, 80 kg K2Oha-1+5.0 t CaCO3ha-1+20 tha-1 stajnjaka). Na osnovu proučavanih parametara sorta ozimog ječma NS 565 je bila tolerantnija na nepovoljne hemijske karakteristike zemljišta (niska pH, nizak sadržaj P2O5 i visok sadržaj mobilnog Al) i može se preporučiti kao pogodan genotip za proizvodnju ječma na kiselim zemljištima, naročito posle njihove kalcizacije

Influence of carbon dioxide content in the biogas to nitrogen oxides emissions

U radu je prikazano eksperimentalno istraživanje i analiza uticaja sadržaja ugljen-dioksida u biogasu na emisiju azotnih oksida. Sagorevanje biogasa različitog sastava vršeno je vihornim gorionikom sa pilot gorionikom. Rezultati pokazuju da postoji uticaj sadržaja ugljen-dioksida na emisiju azotnih oksida, i to tako da sa povećanjem sadržaja ugljen-dioksida emisija azotnih oksida opada. Ovakav trend je nepromenjen u opsegu koeficijenta viška vazduha (1,2-1,8) za koje je vršeno istraživanje. Utvrđeno je da pri nepromenjenom sastavu biogasa promena toplotne snage nema uticaja na emisiju azotnih oksida.Fuels derived from biomass are an alternative solution for the fossil fuel shortage. Usually fuels of this kind are called low calorific value fuels, due to the large proportion of inert components in their composition. The most common is carbon dioxide, and its proportion in biogas can be different, from 10 up to 40%, or even more. The presence of inert component in the composition of biogas causes problems that are related with flame blow off limits. One of the possibilities for efficient combustion of biogas is the combustion in swirling flow including a pilot burner, aimed to expand the borders of stable combustion. This paper presents an analysis of the influence of the carbon dioxide content on nitrogen oxides emissions. Laboratory biogas was used with different content of CO2 (10, 20, 30 and 40%). The investigation was carried out for different nominal powers, coefficients of excess air and carbon dioxide content. With increasing content of carbon dioxide, emission of nitrogen oxides was reduced, and this trend was the same throughout the whole range of excess air, carried out through measurements. Still, the influence of carbon dioxide content is significantly smaller than the influence of excess air. The coefficient of excess air greatly affects the production of radicals which are essential for the formation of nitrogen oxides, O, OH and CH. Also, the results show that the nominal power has no impact on the emission of nitrogen oxides

Research and development of efficient, environmentally improved household gas appliances

An experimental research and analysis of performance of three domestic house hold gas appliances was carried out. The objective of this work, based on the conducted analysis of the research data, was to improve the appliances’ performance, prefer ably through relative simple modifications, in order to satisfy DIN 4702 emissions and efficiency standards when using different fuels, including natural gas, liquefied petroleum gases and lower quality natural gas. This report summarizes details of this work and how the objectives were achieved