Benefits of centralized log file correlation

NORSK: Nettverks administratorer kan korrelere oppføringer i loggfiler manuelt, problemet med slike tilnærminger er manglende grad av fleksibilitet, det er tidkrevende, og man får ikke overblikket over loggfilene i nettverket. Uten dette overblikket er det vanskelig å korrelere informasjon mellom nettverkskomponenter, og hendelser som tilsynelatende er uvesentlige for seg selv, kan i virkeligheten være en bit i et større trusselbilde. Denne oppgaven ser på noen av de produktene som eksisterer i dag, og forsøker å samsvare erfaringer og design prinsipper fra informasjon og whitepapers som finnes på deres hjemmesider, med forskning på området. Mange påstander finnes i litteraturen, men det har ikke vært mulig å finne forskning som forsøker å måle de påståtte gevinstene med slike tilnærminger. Som vi skal se består ett slikt system av flere deler, og i denne oppgaven er det utviklet den enkleste form for prototyp som sentraliserer loggfiler fra ett lite nettverk, og tilbyr muligheten til å browse og søke i disse loggfilene. Hensikten med prototypen er å påvise at det med minimal innsats er mulig å redusere tidsforbruket ved loggfilkorrelasjon med et slikt system, i den forbindelse er det utviklet metrikker for å måle forskjellen i tidsforbruk i et nettverk med prototypen og et nettverk uten prototypen.ENGELSK: Network administrators are able to correlate log file entries manually. The problem with this approach is lack of flexibility, it is time consuming, and one doesn’t get the general view of the log files in the network. Without this general view it is hard to correlate information between the network components, and events seemingly unessential by them selves, can in reality be a piece of a larger threat. This thesis analyses some of the existing products, and tries to correspond experience and design principles found in the information and whitepapers on their web pages with research in this area. A lot of claims are found in the literature, but it has not been possible to find any research trying to measure the alleged benefits of the approaches. As we shall see, such systems consist of several parts, and in this thesis the simplest form of prototype that centralizes log files from a small network is developed that gives the ability to browse and search in these log files. The purpose of the prototype is to prove that it is possible with minimal effort to reduce the time consumption doing log file correlation with such a system. In conjunction with this, metrics are developed to measure the difference in time consumed in a network with the prototype and a network without the prototype

Gaussian process regression with functional covariates and multivariate response

Gaussian process regression (GPR) has been shown to be a powerful and effective nonparametric method for regression, classification and interpolation, due to many of its desirable properties. However, most GPR models consider univariate or multivariate covariates only. In this paper we extend the GPR models to cases where the covariates include both functional and multivariate variables and the response is multidimensional. The model naturally incorporates two different types of covariates: multivariate and functional, and the principal component analysis is used to de-correlate the multivariate response which avoids the widely recognised difficulty in the multi-output GPR models of formulating covariance functions which have to describe the correlations not only between data points but also between responses. The usefulness of the proposed method is demonstrated through a simulated example and two real data sets in chemometrics

Bomb-¹⁴C analysis of ecosystem respiration reveals that peatland vegetation facilitates release of old carbon

The largest terrestrial-to-atmosphere carbon flux is respired CO<sub>2</sub>. However, the partitioning of soil and plant sources, understanding of contributory mechanisms, and their response to climate change are uncertain. A plant removal experiment was established within a peatland located in the UK uplands to quantify respiration derived from recently fixed plant carbon and that derived from decomposition of soil organic matter, using natural abundance <sup>13</sup>C and bomb-<sup>14</sup>C as tracers. Soil and plant respiration sources were found respectively to contribute ~ 36% and between 41-54% of the total ecosystem CO<sub>2</sub> flux. Respired CO<sub>2</sub> produced in the clipped (‘soil’) plots had a mean age of ~ 15 years since fixation from the atmosphere, whereas the <sup>14</sup>C content of ecosystem CO<sub>2</sub> was statistically indistinguishable from the contemporary atmosphere. Results of carbon mass balance modelling showed that, in addition to respiration from bulk soil and plant respired CO<sub>2</sub>, a third, much older source of CO<sub>2</sub> existed. This source, which we suggest is CO<sub>2</sub> derived from the catotelm constituted between ~ 10 and 23% of total ecosystem respiration and had a mean radiocarbon age of between several hundred to ~ 2000 years before present (BP). These findings show that plant-mediated transport of CO<sub>2</sub> produced in the catotelm may form a considerable component of peatland ecosystem respiration. The implication of this discovery is that current assumptions in terrestrial carbon models need to be re-evaluated to consider the climate sensitivity of this third source of peatland CO<sub>2</sub>

Development and Comparison of Estimation Methods for Attitude Determination

The NTNU Test Satellite (NUTS) project, is part of the Norwegian Student Satellite programANSAT. The goal of the project is to design and launch a double CubeSat by the endof 2014. During earlier satellite projects at NTNU, solid work on design of the attitudedetermination and control for a small satellite has been done.One of the considered estimation methods for the attitude determination is the extendedquaternion estimation method (EQUEST). Further development and testing of themethod is described in this thesis. In addition to the new EQUEST method, a nonlinearobserver has been implemented and tested. The simulation results for the two methods arecompared in order to find the attitude estimation method best suited for the NUTS satellite.The new EQUEST method has several advantages over the more common Kalmanfiltering for use in small CubeSats. It is less computationally costly, and has a fast startupand settling time. Magnetorquers, which affect the local magnetic field, are used asactuators for the satellite. This makes a fast algorithm preferable, since the attitude estimationand the attitude control should be performed separately. The nonlinear observer isslower than the EQUEST method, but it can guarantee global exponential stability and itis less vulnerable to disturbances. It is therefore introduced as an alternative solution forthe attitude determination problem.The original EQUEST method builds upon the QUEST method which has been extendedto include non-vectorized terms for gyroscope measurements and attitude predictionin the method s cost function. In these terms, subtractions between the estimated andmeasured quaternions are used. The result is not entirely mathematically correct, eventhough previous testing of the method has been successful. The subtractions in the includedterms will not result in new attitude error quaternions.In this thesis, the method is further developed by replacing the subtraction terms withquaternion products. The new method is tested and compared to the original EQUESTmethod and an extended Kalman filter. It is also compared to the implemented nonlinearobserver. If the computational power of the NUTS satellite is sufficiently large, a combinationof the developed EQUEST method and the nonlinear observer could be considered forthe estimation. A combination of these two attitude estimation methods is implementedand the simulation results are analyzed

Microbial communities respond to experimental warming, but site matters

Because microorganisms are sensitive to temperature, ongoing global warming is predicted to influence microbial community structure and function. We used large-scale warming experiments established at two sites near the northern and southern boundaries of US eastern deciduous forests to explore how microbial communities and their function respond to warming at sites with differing climatic regimes. Soil microbial community structure and function responded to warming at the southern but not the northern site. However, changes in microbial community structure and function at the southern site did not result in changes in cellulose decomposition rates. While most global change models rest on the assumption that taxa will respond similarly to warming across sites and their ranges, these results suggest that the responses of microorganisms to warming may be mediated by differences across the geographic boundaries of ecosystems

Nitrate stable isotopes and major ions in snow and ice samples from four Svalbard sites

Increasing reactive nitrogen (N-r) deposition in the Arctic may adversely impact N-limited ecosystems. To investigate atmospheric transport of N-r to Svalbard, Norwegian Arctic, snow and firn samples were collected from glaciers and analysed to define spatial and temporal variations (1 10 years) in major ion concentrations and the stable isotope composition (delta N-15 and delta O-18) of nitrate (NO3-) across the archipelago. The delta N-15(NO3-) and delta O-18(NO3-) averaged -4 parts per thousand and 67 parts per thousand in seasonal snow (2010-11) and -9 parts per thousand and 74 parts per thousand in firn accumulated over the decade 2001-2011. East-west zonal gradients were observed across the archipelago for some major ions (non-sea salt sulphate and magnesium) and also for delta N-15(NO3-) and delta O-18(NO3-) in snow, which suggests a different origin for air masses arriving in different sectors of Svalbard. We propose that snowfall associated with long-distance air mass transport over the Arctic Ocean inherits relatively low delta N-15(NO3-) due to in-transport N isotope fractionation. In contrast, faster air mass transport from the north-west Atlantic or northern Europe results in snowfall with higher delta N-15(NO3-) because in-transport fractionation of N is then time-limited

Land use not litter quality is a stronger driver of decomposition in hyperdiverse tropical forest

Funded by Natural Environment Research Council. Grant Number: NE/K016253/1Peer reviewedPublisher PD

Rapid prediction of single green coffee bean moisture and lipid content by hyperspectral imaging

Hyperspectral imaging (1000–2500 nm) was used for rapid prediction of moisture and total lipid content in intact green coffee beans on a single bean basis. Arabica and Robusta samples from several growing locations were scanned using a “push-broom” system. Hypercubes were segmented to select single beans, and average spectra were measured for each bean. Partial Least Squares regression was used to build quantitative prediction models on single beans (n = 320–350). The models exhibited good performance and acceptable prediction errors of ∼0.28% for moisture and ∼0.89% for lipids. This study represents the first time that HSI-based quantitative prediction models have been developed for coffee, and specifically green coffee beans. In addition, this is the first attempt to build such models using single intact coffee beans. The composition variability between beans was studied, and fat and moisture distribution were visualized within individual coffee beans. This rapid, non-destructive approach could have important applications for research laboratories, breeding programmes, and for rapid screening for industry

Variability of BVOC Emissions from Commercially Used willow (<i>Salix</i> spp.) Varieties

Willow (Salix spp.) trees are commonly used in short rotation coppices (SRC) to produce renewable energy. However, these plants are also known to emit high concentrations of biogenic volatile organic compounds (BVOCs), which have a large influence on air quality. Many different clones of commercially used Salix varieties exist today, but only a few studies have focused on BVOC emissions from these newer varieties. In this study, four varieties commercially propagated for biofuel production have been studied on a leaf-scale in the southern part of Sweden. The trees had either their first or second growing season, and measurements on BVOC emissions were done during the growing season in 2017 from the end of May to the beginning of September. Isoprene was the dominant emitted compound for all varieties but the average emission amongst varieties varied from 4.00 to 12.66 µg gdw−1 h−1. Average monoterpene (MT) (0.78–1.87 µg gdw−1 h−1) and sesquiterpene (SQT) emission rates (0.22–0.57 µg gdw−1 h−1) differed as well among the varieties. Besides isoprene, other compounds like ocimene, linalool and caryophyllene also showed a response to light but not for all varieties. Younger plants had several times higher emissions of non-isoprenoids (other VOCs) than the corresponding 1-year-old trees. The conclusions from this study show that the choice of variety can have a large impact on the regional BVOC emission budget. Genetics, together with stand age, should be taken into account when modelling BVOC emissions on a regional scale, for example, for air quality assessments