Efeito do fraccionamento da fertilização azotada na cultura da batata

Durante os anos de 1996 a 1998 estudou-se o efeito do fraccionamento da aplicação de azoto na cultura da batata (cv. Desirée). Os ensaios decorreram em Bragança num Cambissolo êutrico. Foram usadas 7 modalidades de fertilização com as seguintes doses de N (fundo + cobertura). 0+0; 200+0; 0÷200; 100÷100; 100+o; 0+100; e 50+50 kg N ha na forma de ureia. Todas as modalidades fertilizadas apresentaram produções unitárias significativamente superiores à modalidade testemunha. Nas modalidades mais produtivas ultrapassaram-se Os 50 Mg ha de tubérculos de calibre comercial

Efficacy and limitations of Triticale as a nitrogen catch crop in a mediterranean environment

During 3 consecutive years (1996/97–1998/99) the efficacy was studied of Triticale as a nitrogen (N) catch crop sown after the harvest of the potato crop cultivated in the preceding summer season under several N fertilizer treatments. In October, shortly after the harvest of the potatoes, there were registered significative differences in the soil N–NO3− levels among N fertilizer treatments of the potato crop. The higher values were recorded on the plots corresponding to higher N doses. At the end of winter, the N status of plants and at the end of experiments (late in April), the N–NO3− in soil, the biomass yield and the N uptake by the catch crop did not reflect the differences registered before in the soil inorganic N. This comparison may suggest that Triticale is little effective in recovering the residual inorganic N of the preceding crop due either to the rainfall occurring in the autumn or to the poor vegetative development of the catch crop during the autumn/winter period. However, at the date of cut, the catch crop removed up to 80 kg N ha−1. At this time, the soil N–NO3− levels were significantly higher on the fallowed plots. This result shows that the crop was very effective in uptaking the N that is mineralized after the end of winter

Efficiency of organic nitrogen fertilization of potato in Northeast Portugal

The study was conducted over a 4 year period with the purpose of measuring N mineralization using an in situ incubation technique, following the application of farmyard manure, poultry manure or municipal solid waste. The results varied from –10 % (net immobilization) to +28 % (net mineralization) in relation to the total organic N applied. N fluxes were assessed through plant N analysis during the growing season and through determination of potato tuber dry weight (TDW), N uptake by tubers and the apparent N recovery (ANR) of added N at harvest. Organic material applications slightly increased TDW above the control treatment (9 to 25%), although the results indicate a shortage of N, where no N was added to the crop. The effect of organic fertilization on N uptake by tubers was also limited. Petiole nitrate concentration and estimated net N mineralization were in agreement with trends in TDW and N uptake by tubers, with no differences in soil N availability between the control and organic treatments. Values of ANR were particularly low, ranging from 4 to 23 %. The results suggest that caution is needed when judging the contribution of organic fertilization to N nutrition of crops, which have a short growing season. Synchronization between N release and plant uptake is discussed

Quantitative sidedress nitrogen recommendations for potatoes based upon crop nutritional indices

The quantification of sidedress N rate from in-season information on crop N nutritional status is extremely important in order to use only the necessary amount of nutrient to achieve maximum yields without significant N losses from soil. During three consecutive years (1996, 1997 and 1998) field N fertilizer experiments with irrigated potato (Solanum tuberosum L., cv. Désirée) were conducted in Bragança (NE Portugal). Eight preplant treatments (0, 50, 100, 200 and 300 kg urea-N/ha and poultry manure, farmyard manure and municipal solid waste in rates equivalent to 100 kg organic-N/ha) were arranged as main plots and five sidedress N rates (0, 25, 50, 100 and 200 kg urea-N/ha) included as subplots. Petiole nitrate concentration, determined by a laboratory method (PNLab, g NO3-N kg−1, dry weight basis) and by the portable RQflex reflectometer (PNRQflex, mg NO3 kg−1, from fresh tissues), and leaf N content (LeafN, g kg−1, dry weight basis) were used as N nutritional indices. From the five sidedress N rates applied over each of the preplant treatments, critical sidedress N rates were estimated for several different crop N nutritional status. This was achieved by establishing exponential asymptotic curves between sidedress N rates and tuber yields and solving the equations for 95% of maximum tuber yield. In a second step, multiple regression equations were established between the estimated critical sidedress N rates (SNrate, kg N/ha), as dependent variable, and each crop N nutritional indices (PNLab, PNRQflex or LeafN) and days after emergence (DAE). The equations obtained are: SNrate = 182.7 − 4.146 × PNLab −1.87 × DAE SNrate = 161.0 − 0.013 × PNRQflex −1.34 × DAE SNrate = 562.2 − 8.416 × LeafN −3.59 × DAE These equations provide quantitative sidedress N rates for any level of crop N nutritional indices and sampling dates from 10 to 48 days after emergence

New Charged Dilaton Solutions in 2+1 Dimensions and Solutions with Cylindrical Symmetry in 3+1 Dimensions

We report a new family of solutions to Einstein-Maxwell-dilaton gravity in 2+1 dimensions and Einstein-Maxwell gravity with cylindrical symmetry in 3+1 dimensions. A set of static charged solutions in 2+1 dimensions are obtained by a compactification of charged solutions in 3+1 dimensions with cylindrical symmetry. These solutions contain naked singularities for certain values of the parameters considered. New rotating charged solutions in 2+1 dimensions and 3+1 dimensions are generated treating the static charged solutions as seed metrics and performing $SL(2;R)$ transformations.Comment: Latex. No figure

Analisis Pengaruh Uprating Transformator Terhadap Nilai Susut Daya Di PT. PLN ULP Indrapura

Sepanjang tahun 2018, PT PLN ULP Indrapura telah melakukan penggantian transformator pada gardu distribusi sebanyak 88 buah, 44 diantarannya dilakukan peningkatan kapasitas daya (uprating) transformator. Uprating transformator pada dasarnya dilakukan untuk mencegah terjadinya overload, sehingga gangguan pada sistem distribusi dapat dihindari dan susut daya pada transformator dapat dikurangi. Namun jika uprating transformator dilakukan tanpa perhitungan dan perencanaan yang tepat, justru dapat meningkatkan susut daya transformator pada gardu distribusi. Uprating transfomator yang telah dilakukan di PT PLN ULP Indrapura perlu dikaji kembali untuk mengetahui perubahan susut yang yang disebabkan oleh uprating transformator pada gardu distribusi. Pada tugas akhir ini akan dilakukan penelitian mengenai aplikasi perhitungan susut transformator pada gardu distribusi AA 233, AA 235, AA 249 dan AA 449. Perhitungan susut daya dilakukan dengan metode Energi Load Flow, Loss Factor Analysis dan simulasi Load Flow pada Digsilent Power Factory 15.1. Dengan menggunakan metode tersebut dapat diperoleh susut daya sebelum dan setelah dilakukan uprating transformator. Susut transformator tersebut selanjutnya digunakan untuk mengestimasi kapasitas daya transformator yang tepat pada gardu distribusi. Hasil perhitungan susut transformator dengan ketiga metode yang telah dilakukan menunjukkan bahwa terjadi peningkatan susut daya setelah dilakukan uprating transformator. Semakin rendah beban setelah uprating transformator, semakin besar peningkatan susut daya yang terjadi. Kondisi underload pada tranformator dapat dihindari dengan menurunkan kapasitas daya transformator. Hasil estimasi kapasitas transformator menunjukkan dengan menurunkan kapasitas transformator pada masing-masing gardu distribusi, dapat menurunkan susut daya. Dari hasil penelitian ini dapat disimpulkan bahwa uprating transformator yang terlalu besar pada gardu distribusi dapat meningkatkan susut daya. =============================================================================================================================== Throughout 2018, PT PLN ULP Indrapura has replaced the transformer at 88 distribution substations, 44 of which are carried out by upgrading the transformer capacity. Uprating transformers are basically done to prevent overload, so that interference with the distribution system can be avoided and the power losses in the transformer can be reduced. But if the uprating transformer is done without proper calculation and planning, it can actually increase the transformer power losses in the distribution substation. Uprating the transfomator that has been carried out at PT PLN ULP Indrapura needs to be reviewed to find out the changes in power losses caused by uprating the transformer at the distribution substation. In this final assignment, a study will be conducted on the application of transformer power losses calculation at AA 233, AA 235, AA 249 and AA 449 distribution substations. Calculation of power losses is done by the method of Energy Load Flow, Loss Factor Analysis and Load Flow simulation on Digsilent Power Factory 15.1. Using this method can be obtained before and after uprating the transformer. The transformer power shrinkage is then used to estimate the transformer power capacity that is right at the distribution substation. The calculation results of transformer power losses with the three methods that have been carried out show that there is an increase in power losses after uprating the transformer. The lower the load after uprating the transformer, the greater the increase in power losses that occur. Underload conditions on the transformer can be avoided by reducing the transformer power capacity. The results of the transformer capacity estimation show that by reducing the transformer capacity at each distribution substation, it can reduce power losses. From the results of this study it can be concluded that uprating transformers that are too large in the distribution substations can increase power losses

A customizable open-source framework for measuring and equalizing e2e delays in shared video watching

Low-latency and media sync are essential requirements to enable interactive multi-party services, such as Social TV. In this work, we present an open-source and customizable framework that allows measuring end-to-end (e2e) video delays and provides support for different type

Dual branes in topological sigma models over Lie groups. BF-theory and non-factorizable Lie bialgebras

We complete the study of the Poisson-Sigma model over Poisson-Lie groups. Firstly, we solve the models with targets $G$ and $G^*$ (the dual group of the Poisson-Lie group $G$) corresponding to a triangular $r$-matrix and show that the model over $G^*$ is always equivalent to BF-theory. Then, given an arbitrary $r$-matrix, we address the problem of finding D-branes preserving the duality between the models. We identify a broad class of dual branes which are subgroups of $G$ and $G^*$, but not necessarily Poisson-Lie subgroups. In particular, they are not coisotropic submanifolds in the general case and what is more, we show that by means of duality transformations one can go from coisotropic to non-coisotropic branes. This fact makes clear that non-coisotropic branes are natural boundary conditions for the Poisson-Sigma model.Comment: 24 pages; JHEP style; Final versio