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Search Results: 1 - 10 of 297872 matches for " J. Olsson "
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Spatio-temporal precipitation error propagation in runoff modelling: a case study in central Sweden
J. Olsson
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2006,
Abstract: The propagation of spatio-temporal errors in precipitation estimates to runoff errors in the output from the conceptual hydrological HBV model was investigated. The study region was the Gim n catchment in central Sweden, and the period year 2002. Five precipitation sources were considered: NWP model (H22), weather radar (RAD), precipitation gauges (PTH), and two versions of a mesoscale analysis system (M11, M22). To define the baseline estimates of precipitation and runoff, used to define seasonal precipitation and runoff biases, the mesoscale climate analysis M11 was used. The main precipitation biases were a systematic overestimation of precipitation by H22, in particular during winter and early spring, and a pronounced local overestimation by RAD during autumn, in the western part of the catchment. These overestimations in some cases exceeded 50% in terms of seasonal subcatchment relative accumulated volume bias, but generally the bias was within ±20%. The precipitation data from the different sources were used to drive the HBV model, set up and calibrated for two stations in Gim n, both for continuous simulation during 2002 and for forecasting of the spring flood peak. In summer, autumn and winter all sources agreed well. In spring H22 overestimated the accumulated runoff volume by ~50% and peak discharge by almost 100%, owing to both overestimated snow depth and precipitation during the spring flood. PTH overestimated spring runoff volumes by ~15% owing to overestimated winter precipitation. The results demonstrate how biases in precipitation estimates may exhibit a substantial space-time variability, and may further become either magnified or reduced when applied for hydrological purposes, depending on both temporal and spatial variations in the catchment. Thus, the uncertainty in precipitation estimates should preferably be specified as a function of both time and space.
Evaluation of a scaling cascade model for temporal rain- fall disaggregation
J. Olsson
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 1998,
Abstract: The possibility of modelling the temporal structure of rainfall in southern Sweden by a simple cascade model is tested. The cascade model is based on exact conservation of rainfall volume and has a branching number of 2. The weights associated with one branching are 1 and 0 with probability P(1/0), 0 and 1 with P(0/1), and Wx/x, and 1 - Wx/x, 0 < Wx/x, < 1, with P(x/x), where Wx/x is associated with a theoretical probability distribution. Furthermore, the probabilities p are assumed to depend on two characteristics of the rainy time period (wet box) to be branched: rainfall volume and position in the rainfall sequence. In the first step, analyses of 2 years of 8-min data indicates that the model is applicable between approximately 1 hour and 1 week with approximately uniformly distributed Wx/x values. The probabilities P show a clear dependence on the box characteristics and a slight seasonal nonstationarity. In the second step, the model is used to disaggregate the time series from 17- to 1-hour resolution. The model-generated data reproduce well the ratio between rainy and nonrainy periods and the distribution of individual volumes. Event volumes, event durations, and dry period lengths are fairly well reproduced, but somewhat underestimated, as was the autocorrelation. From analyses of power spectrum and statistical moments the model preserves the scaling behaviour of the data. The results demonstrate the potential of scaling-based approaches in hydrological applications involving rainfall disaggregation.
Limits and characteristics of the multifractal behaviour of a high-resolution rainfall time series
J. Olsson
Nonlinear Processes in Geophysics (NPG) , 1995,
Abstract: The multifractal properties of a 2-year time series of 8-min rainfall intensity observations are investigated. The empirical probability distribution function suggests a hyperbolic intermittency with divergence of moment of order greater than 2. The power spectrum E(f) of the series obeys a power law form E(f)=f -0.66 in the range of scales 8 min to approximately 3 days. The variation of the average statistical moments with scale shows that the series is characterized by a multifractal behaviour between 8 min and approximately 11 days. The multifractal parameters associated with universality were estimated to be α=0.63 and C1=0,44 by using the Double Trace Moment, DTM, technique. The moment scaling functions obtained from the empirical values and the universal expression are in good agreement in the approximate range 1≤q≤3. Outside of this range, however, differences exist which may be related to either limitations of the data or an inexact estimation of the parameters by DTM. The evident multifractal nature of rainfall time series is encouraging since it may lead to new and improved ways of processing rainfall data used in hydrological calculations.
QCD Studies at HERA
J. Olsson
Physics , 2001,
Abstract: Several topics from the wide field of QCD studies in Deep-inelastic $ep$ Scattering at HERA are addressed. They include QCD analyses of the inclusive cross section with the determination of $\alpha_s$ and the proton gluon density from the $F_2$ scaling violations, and the determination of the longitudinal structure function $F_L$. QCD analyses of inclusive jet and dijet data are also presented. Finally jet substructure and three-jet production are discussed.
A New Measurement of Exclusive \boldmath$ρ^{\circ}$ Photoproduction at HERA
J. Olsson
Statistics , 2006,
Abstract: Exclusive $\rho^{\circ}$ photoproduction has been measured with high statistics by the H1 Collaboration. The kinematical range is $20 < W < 90$ GeV, $|t|<3$ GeV$^2$ and $Q^2<4$ GeV$^2$. Cross sections are measured differentially in $W$ and $t$ and allow the extraction of the Pomeron trajectory, for the first time using $\rho^{\circ}$ photoproduction data of one single experiment. The preliminary result, $\alpha_{\mathbb{P}} (t) = 1.093 \pm 0.003 (stat.) ^{+0.008}_{-0.007} (syst.) + (0.116 \pm 0.027 (stat.) ^{+0.036}_{-0.046} (syst.)$ GeV$^{-2} \cdot t$, deviates significantly from the canonical expectation.
Life Cycle Assessment and Life Cycle Cost of Waste Management—Plastic Cable Waste  [PDF]
Mats Zackrisson, Christina J?nsson, Elisabeth Olsson
Advances in Chemical Engineering and Science (ACES) , 2014, DOI: 10.4236/aces.2014.42025
Abstract:

The main driver for recycling cable wastes is the high value of the conducting metal, while the plastic with its lower value is often neglected. New improved cable plastic recycling routes can provide both economic and environmental incentive to cable producers for moving up the “cable plastic waste ladder”. Cradle-to-gate life cycle assessment, LCA, of the waste management of the cable scrap is suggested and explained as a method to analyze the pros and cons of different cable scrap recycling options at hand. Economic and environmental data about different recycling processes and other relevant processes and materials are given. Cable producers can use this data and method to assess the way they deal with the cable plastic waste today and compare it with available alternatives and thus illuminate the improvement potential of recycling cable plastic waste both in an environmental and in an economic sense. The methodology applied consists of: cradle-to-gate LCA for waste material to a recycled material (recyclate); quantifying the climate impact for each step on the waste ladder for the specific waste material; the use of economic and climate impact data in parallel; climate impact presented as a span to portray the insecurities related to which material the waste will replace; and possibilities for do-it-yourself calculations. Potentially, the methodology can be useful also for other waste materials in the future.

Dancing Combines the Essence for Successful Aging
C.-J. Olsson
Frontiers in Neuroscience , 2012, DOI: 10.3389/fnins.2012.00155
Abstract:
Pentaquark Searches in H1
J. E. Olsson
Physics , 2007,
Abstract: We report on searches in deep inelastic $ep$ scattering for narrow baryonic states decaying into $\Xi^-\pi^-, \Xi^-\pi^+, \KS p$ and their charge conjugates, at centre-of-mass energies of 300 and 318 GeV. No signal for a new narrow baryonic state is observed in the mass ranges 1600-2100 MeV ($\Xi\pi$) and from threshold up to 1700 MeV ($\KS p$). The standard baryon $\Xi(1530)^0$ is observed in the decay mode $\Xi^-\pi^+$, and mass dependent upper limits on the ratio of the hypothetical pentaquark states $\Xi^{--}_{5q}$ and $\Xi^0_{5q}$ to the $\Xi(1530)^0$ signal are given. Also for the hypothetical strange pentaquark $\Theta^+$ mass dependent upper limits on $\sigma(ep\to e\Theta^+X)\times BR(\Theta^+\to K^0p)$ are obtained. Finally measurements of the acceptance corrected ratios $\sigma(D^{\ast}p(3100))/\sigma(D^{\ast})$ for the electroproduction of the anti-charmed baryon state $D^{\ast}p(3100)$ decaying into $D^{\ast}$ and $p$ are presented.
A theorem on the cores of partitions
J. B. Olsson
Mathematics , 2008,
Abstract: If s and t are relatively prime positive integers we show that the s-core of a t-core partition is again a t-core partition
Tensor Correlations and Pions in Dense Nuclear Matter
E. Olsson,C. J. Pethick
Physics , 2002,
Abstract: The study of tensor correlations and pions in dense matter in astronomical contexts has recently acquired renewed importance for a number of reasons. One is the discovery by Akmal, and Pandharipande (Phys. Rev. C56 2261 (1997)) of a striking increase in tensor correlations in cold matter at densities not far above that of isospin-symmetric nuclear matter at saturation. A second is that, according to a calculation by Mayle and Wilson, softening of the equation of state by the appearance of thermal pions can play an important role. A third is that the strength of tensor correlations is a crucial ingredient in calculating rates of neutrino emission and scattering, which are needed in calculations of stellar collapse and of the cooling of neutron stars. We describe some recent results for the response of nuclear matter when tensor interactions are taken into account, and indicate some unresolved issues.
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