Evaluation of Spatial interpolation techniques for mapping climate variables with low sample density: a case study using a new gridded dataset of Bangladesh

Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.This study explores and analyses the impact of sample density on the performances of the spatial interpolation techniques. It evaluates the performances of two alternative deterministic techniques – Thin Plate Spline and Inverse Distance Weighting, and two alternative stochastic techniques – Ordinary Kriging and Universal Kriging; to interpolate two climate indices - Annual Total Precipitation in Wet Days and the Yearly Maximum Value of the Daily Maximum Temperature, in a low sample density region - Bangladesh, for 60 years – 1948 to 2007. It implies the approach of Spatially Shifted Years to create mean variograms with respect to the low sample density. Seven different performance measurements - Mean Absolute Error, Root Mean Square Errors, Systematic Root Mean Square Errors, Unsystematic Root Mean Square Errors, Index of Agreement, Coefficient of Variation of Prediction and Confidence of Prediction, have been applied to evaluate the performance of the spatial interpolation techniques. The resulted performance measurements indicate that for most of the years the Universal Kriging method performs better to interpolate total precipitation, and the Ordinary Kriging method performs better to interpolate the maximum temperature. Though the difference surfaces indicate a very little difference in the estimating ability of the four spatial interpolation techniques, the residual plots refer to the differences in the interpolated surfaces by different techniques in terms of their over and under estimation. The results also indicate that the Inverse Distance Weighting method performs better for both indices, when the sample density is too low, but the performance is questioned by the inclusion of measurement errors in the interpolated surfaces. All the error measurements show a decreasing trend with the increasing sample density, and the index of agreement and confidence of prediction show an increasing trend over years. Finally, the strong correlation between the Sample Coefficient of Variation and the performance measurements, implies that the more representative the samples are of the climate phenomenon, the more improved are the performances of the spatial interpolation techniques. The correlation between the sample coefficient of variation and the number of samples implies that the high representativity of the sample is attainable with an increased sample density

Essais d'utilisation de "nourrisseur à la demande" pour l'alimentation de Chrysichthys nigrodigitatus en cage-enclos

An experiment using demand feeder was carried out on the catfish Chrysichthys nigrodigitatus reared in cage-enclosure in the lagoon Ebrié (Côte d'Ivoire). The study lasted 5 months, from October to March, and showed that the demand feeder improves the growth rate of the fish and the feed conversion. It was able, as well as the conventional hand feeding, to show monthly variations of performances

Data Scarcity or low Representativeness?: What hinders accuracy and precision of spatial interpolation of climate data?

Ponencias, comunicaciones y pósters presentados en el 17th AGILE Conference on Geographic Information Science "Connecting a Digital Europe through Location and Place", celebrado en la Universitat Jaume I del 3 al 6 de junio de 2014.Data scarcity is a major scientific challenge for accuracy and precision of spatial interpolation of climatic fields, especially in climatestressed developing countries. Methodologies have been suggested for coping up with data scarcity but data have rarely been checked for their representativeness of corresponding climatic fields. Here, influences of number and representativeness of climate data on accuracy and precision of their spatial interpolation were investigated and compared. Two precipitation and temperature indices were computed for a long time series in Bangladesh, which is a data scarce region. The representativeness was quantified by dispersion in the data and the accuracy and precision of spatial interpolation were computed by four commonly used error statistics derived through cross-validation. The precipitation data showed very little and sometimes null representativeness whereas the temperature data showed very high representativeness of the corresponding fields. Consequently, interpolated precipitation surfaces showed little accuracy and precision whereas temperature surfaces showed high accuracy and precision despite the scarce data. The results indicate that representativeness of climate data, i.e. variability of climate phenomenon, is more crucial than the number of data for accuracy and precision of spatial interpolation and should be treated with higher importance

A geostatistical approach to the seasonal precipitation effect on Boro rice production in Bangladesh

Bhowmik, A. K., & Costa, A. C. (2012). A geostatistical approach to the seasonal precipitation effect on Boro rice production in Bangladesh. International Journal of Geosciences, 3(3), 443-462. DOI: 10.4236/ijg.2012.33048Geographical assessments on the relationship between climate variability and crop production are important for planning adaptation programs to climate change impacts on Asian rice production. This paper analyses the seasonal precipitation consequences to irrigated crop yields, in opposition to the idea that irrigated crop yields are not affected by precipitation changes. Geostatistical methods are applied to assess changes in the patterns of seasonal precipitation and corresponding changes in the Boro crop production in Bangladesh. Surfaces depicting changes in the monsoon, non-monsoon and total precipitation from 2006 to 2007, and changes in three varieties of Boro crop yield and Total Boro yield from 2006-2007 to 2007-2008 crop years are generated through Splines, Inverse Distance Weighting and Ordinary Kriging methods. Performance evaluation of these models is also performed. The relationships between the surfaces of different precipitation seasons and the surfaces of different Boro yield seasons are then assessed. The results show that there is a significant correlation between seasonal precipitation changes and Boro yield changes with notable correlation coefficients and similarity in the patterns. A significant conformity of the high precipitation zones to the high Boro yielding zones is also depicted.publishersversionpublishe

Les acadjas traditionnels dans le sud-est du Bénin

This study mission on acadja, the traditional way of fishing in the lagoons of the South-East part of Benin, permits us to understand how well-established this fishing practice is, in terms of time and spatial extention. The exploitation of acadja has a great profitability but it also represents the source of some problems as deterioration of branches, deforestation and social conflits. However, when acadjas are rationally exploited, they constitute a hope for waters which are in the process of losing their biological richness

Micro- et nanofils de Ga (In)N et GaAs par épitaxie en phase vapeur par la méthode aux hydrures (HVPE)

The manuscript deals with the growth of Ga(In)N and GaAs micro- and nanowires by hydride vapor phase epitaxy (HVPE). HVPE is an original growth process with very high growth rates. This particular feature is due to the use of chloride molecules as element III precursors. Selective area growth of arrays of GaN microwires on silicon substrates covered by a dielectric mask, with or without an intermediate AlN buffer layer, is studied. We show that without the AlN buffer layer, nucleation of many wires in a single opening cannot be prevented. On the other hand, with an intermediate AlN buffer layer between the silicon substrate and the dielectric mask, the growth of arrays of microwires with high crystalline and optical properties is achieved. A theoretical and experimental study of the growth of InGaN is carried out. Results show that with InCl as indium precursor, synthesis of InGaN is difficult, but the use of InCl 3 precursors makes it easier. The growth of core/shell GaN/AlN nanowires on c-sapphire substrates in a single step process is demonstrated. A mixed VLS/VS growth mechanism is proposed as explanation. The stability of the Zinc-Blende phase in ultra-long and 10 nanometers in diameter GaAs nanowires grown by Au-assisted VLS is experimentally demonstrated for the first time. This is successfully explained by a nucleation model involving thermodynamic and kinetic considerations.Le manuscrit traite de l'épitaxie en phase vapeur par la méthode aux hydrures (HVPE) de micro- et nanofils Ga(In)N et GaAs. La HVPE est une méthode de croissance originale qui utilise des précurseurs en éléments III chlorés permettant des vitesses de croissance importantes. La croissance sélective de réseaux de microfils GaN sur des substrats silicium avec et sans couche tampon d'AlN, masqués par un diélectrique, est étudiée. Nous montrons que sans la couche tampon, la nucléation de plusieurs fils par ouverture a lieu. Par contre, l'emploi d'une couche tampon d'AlN entre le masque diélectrique et le substrat silicium permet la synthèse de réseaux de fils de grande qualité cristalline et optique par HVPE. Une étude théorique et expérimentale de la croissance d'InGaN par HVPE est effectuée. Les résultats indiquent qu'avec un précurseur pour l’élément indium de type InCl, la synthèse d'InGaN est très difficile ; mais, qu'elle est en revanche facilitée par l'emploi d'un précurseur de type InCl 3 . Nous démontrons la croissance de nanofils GaN/AlN coeur/coquille sur substrat saphir plan c en une seule étape. Un mécanisme original mixte VLS-VS est proposé en guise d'explication. La stabilité de la phase Zinc-Blende de nanofils GaAs, ultra-longs et de diamètre 10 nm, obtenus par un procédé VLS catalysé Au, est démontrée pour la première fois expérimentalement et est expliquée grâce à un modèle thermodynamique et cinétique de nucléation

Pengaruh Dimensi Electronic Word of Mouth (E-Wom) Pada Media Sosial Instagram Terhadap Kesediaan Membeli Chatime (Studi Pada Konsumen Chatime di Purwokerto)

Penelitian ini bertujuan untuk mengetahui dan menganalisis pengaruh variabe Concern for The Others, Expressing Positive Feelings, Economic Incentives, Helping The Company, dan Platform Assistance terhadap sikap dan sikap (Y1) terhadap kesediaan membeli (Y2). Sampel dalam penelitian ini berjumlah 107 responden yang merupakan konsumen Chatime di Purwokerto. Metode pemilihan sampel dalam penelitian menggunakan metode purposive sampling. Data kemudian dianalisis dengan analisis regresi linier berganda dan analisis regresi linier sederhana. Hasil penelitian menunjukkan bahwa secara parsial Concern for The Others, Expressing Positive Feelings, Helping The Company, dan Platform Assistance berpengaruh pada sikap dan sikap berpengaruh pada kesediaan membeli. Sedangkan, variabel Economic Incentives tidak berpengaruh pada sikap. Model regresi linier berganda memiliki nilai koefisien determinasi adjusted r square sebesar 0,671 memiliki arti bahwa variabel Concern for The Others, Expressing Positive Feelings, Economic Incentives, Helping The Company, dan Platform Assistance mampu mempengaruhi sikap sebesar 67,1%, sedangkan sisanya sebesar 32,9% dipengaruhi oleh variabel lain yang tidak diteliti dalam penelitian ini. Model regresi linier sederhana memiliki nilai koefisien determinasi adjusted r square sebesar 0,513 memiliki arti bahwa variabel sikap mampu mempengaruhi kesediaan membeli sebesar 51,3%, sedangkan sisanya sebesar 48,7% dipengaruhi oleh variabel lain yang tidak diteliti dalam penelitian ini. Variabel dalam penelitian ini yang paling dominan yaitu Helping The Company

Description of Smoking Knowledge and Behavior in Teenager

The efforts to find one's identity begin when entering adolescence accompanied by a desire to try new things including smoking, the percentage of smokers in Mahulu district is the fifth highest in Indonesia. The existence of the phenomenon of adolescents becoming more courageous in showing smoking behavior in public places caused researchers to be interested in knowing the description of smoking knowledge and behavior among adolescents at SMPN 2 Long Pahangai. This descriptive study used a questionnaire as a research instrument and involved all students who met the inclusion criteria so that 111 respondents were obtained. The results obtained were that most of them were in their early teens with 59 people, 62 women, 108 Dayak people, 45 people in class IX, 75 people who had family members who smoked. Most of them are addictive smokers, namely 30 people, use filtered cigarettes, namely 40 people, smoking duration of 1-2 years, namely 24 people, light smoker criteria (1-10 cigarettes/day), namely 42 people, and most of them are at the maintenance of smoking stage. smoking is 30 people. The conclusion obtained from this study is that most of the students at SMPN 2 Long Pahangai have a high level of knowledge about smoking, namely 96 people and most of the students at SMPN 2 Long Pahangai have non-smoking behavior, namely 62 people. It is necessary to increase education efforts regarding the dangers of smoking continuously and counseling about managing stress positively to adolescents at SMPN 2 Long Pahangai. Health education also needs to be given to parent