Combined forecast model involving wavelet-group methods of data handling for drought forecasting

Vigorous efforts to improve the effectiveness of drought forecasting models has yet to yield accurate result. The situation gives room on the use of robust forecasting methods that could effectively improve existing methods. The complex nature of time series data does not enable one single method that is suitable in all situations. Thus, a combined model that will provide a better result is then proposed. This study introduces a wavelet and group methods of data handling (GMDH) by integrating discrete wavelet transform (DWT) and GMDH with transfer functions such as sigmoid and radial basis function (RBF) to form three wavelet-GMDH models known as modified W-GMDH (MW-GMDH), sigmoid W-GMDH (SW-GMDH) and RBF W-GMDH. To assess the effectiveness of this approach, these models were applied to rainfall data at four study stations namely Arau and Kuala Krai in Malaysia as well as Badeggi and Duku-Lade in Nigeria. These data were transformed into four Standardized Precipitation Index (SPI) known as SPI3, SPI6, SPI9 and SPI12. The result shows that the integration of DWT improved the performance of the conventional GMDH model. The combination of these models further improved the performance of each model. The proposed model provides efficient, simple, and reliable accuracy when compared with other models. The incorporation of wavelet to the study results in improving performance for all four stations with the Combined W-GMDH (CW-GMDH) and Combined Regression W-GMDH (CRW-GMDH) models. The results show that Duku-Lade station produced the lowest value of 0.0239 and 0.0211 for RMSE and MAE and highest value of 0.9858 for R respectively. In addition, CRW-GMDH model produce the lowest value of 0.0168 and 0.0117, and the highest value of 0.9870 for RMSE MAE, and R respectively. On the percentage improvement, Duku-Lade station shows improvement over other models with the reductions in RMSE and MAE by 42.3% and 80.3% respectively. This indicates that the model is most suitable for the drought forecasting in this station. The results of the comparison among the four stations indicate that the CW-GMDH and CRW-GMDH models are more accurate and perform better than MW-GMDH, SW-GMDH and RBFW-GMDH models. However, the overall performance of the CRW-GMDH model outweigh that of the CW-GMDH model. In conclusion, CRW-GMDH model performs better than other models for drought forecasting and capable of providing a promising alternative to drought forecasting technique

Hierarchical bayesian methods for the marine sciences:analyses of climate variability and fish abundance

Tese de doutoramento, Ciências do Mar, 2010, Universidade de Lisboa, Faculdade de CiênciasOs radicais orgânicos são espécies importantes em quase todos os domínios daquímica e bioquímica. Contudo, apesar da sua existência ter sido documentadahá mais de uma centena de anos, uma fracção significativa da energéticadestas espécies é ainda desconhecida. Uma propriedade termoquímica crucialno estudo de um radical é a entalpia associada à quebra da ligação (BDE)que dá origem a esse radical. Estas BDEs podem ser obtidas experimentalmenteatravés de calorimetria fotoacústica (PAC). A química computacionaltambém pode ser utilizada para fazer previsões rigorosas desta propriedade termoquímica.Os métodos teóricos permitem ainda o acesso directo à estruturade radicais e compostos pais. Neste trabalho, PAC e química computacionalforam utilizadas conjuntamente para estudar a energética de radicais orgânicos.A entalpia de formação padrão do radical ciclopentadienilo e a BDE C H parao 1,3-ciclopentadieno foram reexaminadas. Foi avaliada a precisão de extrapolaçõespara base completa de CCSD(T) e a de métodos de optimização com basena teoria do funcional da densidade. De seguida foi efectuado um estudo detalhadoda energética do grupo alilo. Finalmente, foi estudado o efeito da tensãode anel em hidrocarbonetos cíclicos com cinco e seis membros e respectivosradicais.Organic radicals are important species in virtually every domain of chemistryand biochemistry. However, even though they have been known for morethan 100 years, the energetic data for radicals typically have large uncertaintiesor are missing. One crucial thermochemical property in the study of a radicalis the enthalpy associated with the bond cleavage (BDE) which originates thatradical. BDEs can be obtained experimentally with photoacoustic calorimetry(PAC). Computational chemistry also provides reliable estimates of thisthermochemical property. In addition, theoretical methods provide direct accessto the structure of radicals and their parent compounds. In this work bothPAC and computational chemistry were used to study the energetics of organicradicals. The standard enthalpy of formation for the cyclopentadienyl radicaland the 1,3-cyclopentadienyl C H BDE were re-examined. We proceeded toassess the accuracy of cost-efficient CCSD(T) complete basis set extrapolationschemes and density functional theory optimization methods for radicals. Adetailed analysis of the energetics of the allyl moiety was then conducted. Finally,the effect of ring strain on five- and six-membered ring hydrocarbons andrespective radicals was discussed

Proceedings of the 36th International Workshop Statistical Modelling July 18-22, 2022 - Trieste, Italy

The 36th International Workshop on Statistical Modelling (IWSM) is the first one held in presence after a two year hiatus due to the COVID-19 pandemic. This edition was quite lively, with 60 oral presentations and 53 posters, covering a vast variety of topics. As usual, the extended abstracts of the papers are collected in the IWSM proceedings, but unlike the previous workshops, this year the proceedings will be not printed on paper, but it is only online. The workshop proudly maintains its almost unique feature of scheduling one plenary session for the whole week. This choice has always contributed to the stimulating atmosphere of the conference, combined with its informal character, encouraging the exchange of ideas and cross-fertilization among different areas as a distinguished tradition of the workshop, student participation has been strongly encouraged. This IWSM edition is particularly successful in this respect, as testified by the large number of students included in the program

African Handbook of Climate Change Adaptation

This open access book discusses current thinking and presents the main issues and challenges associated with climate change in Africa. It introduces evidences from studies and projects which show how climate change adaptation is being - and may continue to be successfully implemented in African countries. Thanks to its scope and wide range of themes surrounding climate change, the ambition is that this book will be a lead publication on the topic, which may be regularly updated and hence capture further works. Climate change is a major global challenge. However, some geographical regions are more severly affected than others. One of these regions is the African continent. Due to a combination of unfavourable socio-economic and meteorological conditions, African countries are particularly vulnerable to climate change and its impacts. The recently released IPCC special report "Global Warming of 1.5º C" outlines the fact that keeping global warming by the level of 1.5º C is possible, but also suggested that an increase by 2º C could lead to crises with crops (agriculture fed by rain could drop by 50% in some African countries by 2020) and livestock production, could damage water supplies and pose an additonal threat to coastal areas. The 5th Assessment Report produced by IPCC predicts that wheat may disappear from Africa by 2080, and that maize— a staple—will fall significantly in southern Africa. Also, arid and semi-arid lands are likely to increase by up to 8%, with severe ramifications for livelihoods, poverty eradication and meeting the SDGs. Pursuing appropriate adaptation strategies is thus vital, in order to address the current and future challenges posed by a changing climate. It is against this background that the "African Handbook of Climate Change Adaptation" is being published. It contains papers prepared by scholars, representatives from social movements, practitioners and members of governmental agencies, undertaking research and/or executing climate change projects in Africa, and working with communities across the African continent. Encompassing over 100 contribtions from across Africa, it is the most comprehensive publication on climate change adaptation in Africa ever produced

Generalized averaged Gaussian quadrature and applications

A simple numerical method for constructing the optimal generalized averaged Gaussian quadrature formulas will be presented. These formulas exist in many cases in which real positive GaussKronrod formulas do not exist, and can be used as an adequate alternative in order to estimate the error of a Gaussian rule. We also investigate the conditions under which the optimal averaged Gaussian quadrature formulas and their truncated variants are internal

MS FT-2-2 7 Orthogonal polynomials and quadrature: Theory, computation, and applications

Quadrature rules find many applications in science and engineering. Their analysis is a classical area of applied mathematics and continues to attract considerable attention. This seminar brings together speakers with expertise in a large variety of quadrature rules. It is the aim of the seminar to provide an overview of recent developments in the analysis of quadrature rules. The computation of error estimates and novel applications also are described