Geostatistical modeling and spatial distribution analysis of porosity and permeability in the Shurijeh-B reservoir of Khangiran gas field in Iran

The main objectives of this study are analysis of spatial behavior of the porosity and permeability, presenting direction of anisotropy for each variable and describing variation of these parameters in Shurijeh B gas reservoir in Khangiran gas field. Porosity well log data of 32 wells are available for performing this geostatistical analysis. A univariate statistical analysis is done on both porosity and permeability to provide a framework for geostatistical analysis and modeling. For spatial analysis of these parameters, the experimental semivariogram of each variable in different direction as well as their variogram map plotted to find out the direction of anisotropy and their geostatistical parameters such as range, sill, and nugget effect for later geostatistical work and finally for geostatistical modeling, two approaches kriging and Sequential Gaussian Simulation are used to get porosity and permeability maps through the entire reservoir. All of statistical and geostatistical analysis has been done using GSLIB and PETREL software. Maximum and minimum direction of continuity are found to be N75W and N15E, respectively. Geostatistical parameters of calculated semivariogram in this direction like range of 7000 m and nugget of 0.2 are used for modeling. Both kriging and SGS method used for modeling but kriging tends to smooth out estimates but on the other hand SGS method tends to show up details. Cross-validation also used to validate the generated modeling

Semiparametric Time Series Models with Log-concave Innovations: Maximum Likelihood Estimation and its Consistency

We study semiparametric time series models with innovations following a log-concave distribution. We propose a general maximum likelihood framework which allows us to estimate simultaneously the parameters of the model and the density of the innovations. This framework can be easily adapted to many well-known models, including ARMA, GARCH and ARMA-GARCH. Furthermore, we show that the estimator under our new framework is consistent in both ARMA and ARMA-GARCH settings. We demonstrate its finite sample performance via a thorough simulation study and apply it to model the daily log-return of FTSE 100 index and the rabbit population.Comment: 38 pages, 4 figure

Simulation of solute transport in a heterogeneous vadose zone describing the hydraulic properties using a multistep stochastic approach

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95612/1/wrcr10619.pd

Distributionally robust L1-estimation in multiple linear regression

Linear regression is one of the most important and widely used techniques in data analysis, for which a key step is the estimation of the unknown parameters. However, it is often carried out under the assumption that the full information of the error distribution is available. This is clearly unrealistic in practice. In this paper, we propose a distributionally robust formulation of L1-estimation (or the least absolute value estimation) problem, where the only knowledge on the error distribution is that it belongs to a well-defined ambiguity set. We then reformulate the estimation problem as a computationally tractable conic optimization problem by using duality theory. Finally, a numerical example is solved as a conic optimization problem to demonstrate the effectiveness of the proposed approach

The pre-vaccination regional epidemiological landscape of measles in Italy: contact patterns, effort needed for eradication, and comparison with other regions of Europe

BACKGROUND: Strong regional heterogeneity and generally sub-optimal rates of measles vaccination in Italy have, to date, hampered attainment of WHO targets for measles elimination, and have generated the need for the new Italian National Measles Elimination Plan. Crucial to success of the plan is the identification of intervention priorities based upon a clear picture of the regional epidemiology of measles derived from the use of data to estimate basic parameters. Previous estimates of measles force of infection for Italy have appeared anomalously low. It has been argued elsewhere that this results from Italian selective under-reporting by age of cases and that the true measles force of infection in Italy is probably similar to that of other European countries. A deeper examination of the evidence for this conjecture is undertaken in the present paper. METHODS: Using monthly regional case notifications data from 1949 to the start of vaccination in 1976 and notifications by age from 1971–76, summary equilibrium parameters (force of infection (FOI), basic reproductive ratio (R(0)) and critical vaccination coverage (p(c))) are calculated for each region and for each of 5 plausible contact patterns. An analysis of the spectra of incidence profiles is also carried out. Finally a transmission dynamics model is employed to explore the correspondence between projections using different estimates of force of infection and data on seroprevalence in Italy. RESULTS: FOI estimates are lower than comparable European FOIs and there is substantial regional heterogeneity in basic reproductive ratios; certain patterns of contact matrices are demonstrated to be unfeasible. Most regions show evidence of 3-year epidemic cycles or longer, and compared with England & Wales there appears to be little synchronisation between regions. Modelling results suggest that the lower FOI estimated from corrected aggregate national data matches serological data more closely than that estimated from typical European data. CONCLUSION: Results suggest forces of infection in Italy, though everywhere remaining below the typical European level, are historically higher in the South where currently vaccination coverage is lowest. There appears to be little evidence to support the suggestion that a higher true force of infection is masked by age bias in reporting

Coping with disrupted lives : a study of Afghan girls and their family networks

The thesis "Coping with disrupted lives, - a study of Afghan girls and their family networks" explores the practical and emotional ways of coping of the generation who has grown up with the war in Afghanistan, and in exile in Peshawar, Pakistan. Based on nine months of fieldwork in 1998/99, the study describes the life histories and the everyday lives of a number of young girls and their families during the various phases of war in Kabul, and in exile across the border. The study is concerned with the "new" refugees; the urban middle class of educated professionals who left Kabul at the outbreak of the civil war. By focusing on a section of the Afghan refugees that has received little attention, I highlight Liisa Malkki's point that refugees are not a homogeneous group. In order to address their concerns and understand their coping strategies, they must be seen in the context of their specific political histories. Peshawar is described as a key place in the Afghan diaspora, and the refugees maintain strong links with Kabul as well as with their extended trans-national family networks. Another objective has been to challenge the tendency in international refugee discourse to view people affected by war and displacement as mere victims. I focus on the young girls as social actors without disregarding the difficult circumstances of their lives, attempting to bring out the coping, creative aspects of their life experiences. The girls live within the context of their families, and I have explored the changes in roles and relations within the households. Many of the girls live in female-headed households, and some are income earners. I explore how the girls adapt their new roles to the ideal of the khub dakhtar, the respectful daughter. The girls have all had their educations disrupted by the war, and dream of a future where they can attend schools and universities. Lack of education and livelihood opportunities in a war stricken Kabul, and increasingly difficult living conditions in Peshawar motivate more and more families to attempt migration. The successful ones are those who are able to mobilize resources in their extended family networks abroad. These networks are crucial to the coping of the girls and their families, and the study concludes that despite drastic changes and geographical dispersal, the role of the family has not diminished; the reciprocity norm in family relations still stands strong. The study also explores the various religious and cultural practices the girls and women draw on in order to cope emotionally with grief and loss, practices rooted in a cosmology that emphasize resilience, dignity and the ethos of hiding ones troubled heart with a smile

Filling the Holes with Workarounds: Watching Maps Work in the Terrain

The actual, situated use of a computer system differs from the use planned by the developers in a range of ways. This masters thesis explores some of the ways in which situated use takes place. Using grounded theory methodology, a series of interviews conducted at a large Norwegian government organization is analyzed, and then complemented with quantitative data from an opinion poll. The thesis identifies several ways of using the system, building on and extending Gasser’s (1986) notion of workarounds and Lévi-Strauss’ bricolage. The thesis further develops a set of characteristics for these constructs, and argues that this presents a useful vocabulary in discussing how situated use of a formal system actually takes place. The thesis concludes that situated use necessarily has to differ from the planned use of a system, and that this is a generative benefit that developers can learn from and facilitate by improving the system to better support situated use

Forståelsen av skybasert ERP: Faktorer som påvirker beslutningen om overgang/adopsjon i SMB-er

Private bedrifter i dagens næringsliv benytter ERP-systemer, som enten er tradisjonelle, hybride eller skybaserte, som en viktig del av sin arbeidshverdag. Ved oppfordring fra vår oppdragsgiver, TietoEvry, ble det uttrykt et ønske om å studere overganger til ERP i sky nærmere, hvor målet var å skape en bedre forståelse for hva en innføring av skybasert Enterprise Resource Planning System (ERP) vil bety for private bedrifter og oppgavegiver. Vår bacheloroppgave setter derfor søkelys på denne overgangen, og skal gjennom bruk av intervjuer og tidligere forskning, besvare vår problemstilling der vi skal studere beslutningsprosessen knyttet til adopsjon/overgang til skybaserte ERP-systemer. Dette vil utforskes gjennom bruken av Technology, Organization and Environment-rammeverket (TOE-rammeverket), der benyttes til å besvare våre forskningsspørsmål knyttet til problemstillingen, hvor intervjustudie videre, vil gi oss empiri som vil bli analysert gjennom rammeverket. ERP-systemer er i dag brukt i bedrifter for å samle alle data i et system og gjøre at denne kan benyttes på tvers av hele bedriften (Bradford, 2015). TOE-rammeverket kan brukes for vår problemstilling, da dette er et generisk rammeverk der brukes til å studere adopsjonsprosesser i bedrifter ved implementasjon av nye systemer (Baker, 2011). I casestudien blir det avdekket en rekke faktorer som påvirker denne beslutningen om skybasert ERP, hvor det belyses sterke likheter innenfor de private små- /mellomstore bedriftene (SMB) som det ble forsket på. Det er likevel tydelig at denne overgangen ikke skiller seg vesentlig fra andre endringer gjennomført tidligere. Beslutningen baserer seg nemlig i stor grad på strategiske elementer med teknologiske spesifikasjoner som da ivaretar tidligere investeringer gjennom en overgang til et skybasert ERP-system