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Nigerian Wood Waste: A Dependable and Renewable Fuel Option for Power Production

World Journal of Engineering and Technology 2014年第3期2卷 234-248页

作者： Kehinde Oluoti Godswill Megwai anita pettersson Tobias Richards Swedish Center for Resource Recovery University of Boras Boras Sweden

Being an oil-rich country, Nigeria’s energy supply is primarily fossil-based. The unequal distribution of oil wealth, along with agitation for self-determination and resource control, has led to the sabotage of oil installations. This, in turn, has affected all services running on the energy supply from these installations, leading to incessant or total shut-down of such facilities. Power generated using biomass-based renewable energy technologies is a promising option in limiting the country’s dependence on fossil energy for power generation. The most important part of this option is on-site power generation via mini-grid systems. The power thus produced is utilized with the excess being fed into the national grid based on Feed-in-Tariff (F.i.T.) requirements and technicalities. The important factors to be considered in the propagation of a mini-grid option are examined in this study. Furthermore, the study shows that about 1.3 TWh of electricity can be generated from the 1.8 million tonnes per year of wood waste produced by the lumber industry in Nigeria. Power generation through the utilization of biomass has however proved to be a possible path in achieving economic, social and environmental sustainability in the country. Economic studies show that for small-scale power generation, internal combustion engines and Stirling engines are economically feasible. Steam turbines and gas turbines are mostly used in medium/large-scale biomass power generators, especially in proximity to biomass waste resources. Micro gas turbine power technology can also be applied on a small scale despite its high total investment capital.

关键词： Nigeria Wood Waste Renewable Energy Mini-Grid Power Technologies

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Plato on Necessity and Disorder

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Frontiers of Philosophy in China 2013年第4期8卷 546-565页

作者： Olof pettersson Department of Philosophy Uppsala University 75126 Uppsala Sweden

In the Timaeus, Plato makes a distinction between reason and necessity. This distinction is often accounted for as a distinction between two types of causation： purpose oriented causation and mechanistic causation. While reason is associated with the soul and taken to bring about its effects with the good and the beautiful as the end, necessity is understood in terms of a set of natural laws pertaining to material things. In this paper I shall suggest that there are reasons to reconsider the latter part of this account and argue for a non-mechanistic understanding of necessity. I will first outline how the notion of necessity is introduced in the dialogue. Next I will show how a mechanistic account of necessity fails to capture Plato＇s purpose of treating it as a causal factor; and, finally, I will argue that this purpose is better understood as an attempt, on Plato＇s part, to account for the causal origin of disorder and irrationality, an origin articulated in terms of a pre-cosmic situation and the notoriously difficult notion of the third kind.

关键词： Plato Timaeus causation reason necessity disorder

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BOUNDARY PROCEDURES FOR THE TIME-DEPENDENT BURGERS' EQUATION UNDER UNCERTAINTY

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Acta Mathematica Scientia 2010年第2期30卷 539-550页

作者： Per pettersson Jan Nordstrm Gianluca Iaccarino Mechanical Engineering and Institute for Computational Mathematical Engineering Stanford University Division of Scientific Computing Department of Information TechnologyUppsala University School of Mechanical Industrial and Aeronautical EngineeringUniversity of the Witvatersrand Department of Aeronautics and Systems Integration FOIThe Swedish Defense Research Agency

The Burgers＇ equation with uncertain initial and boundary conditions is approximated using a Polynomial Chaos Expansion （PCE） approach where the solution is represented as a series of stochastic, orthogonal polynomials. The resulting truncated PCE system is solved using a novel numerical discretization method based on spatial derivative operators satisfying the summation by parts property and weak boundary conditions to ensure stability. The resulting PCE solution yields an accurate quantitative description of the stochastic evolution of the system, provided that appropriate boundary conditions are available. The specification of the boundary data is shown to influence the solution; we will discuss the problematic implications of the lack of precisely characterized boundary data and possible ways of imposing stable and accurate boundary conditions.

关键词： stochastic Burgers' equation uncertainty quantification polynomial chaos

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Reduced peripheral vascular reactivity in refractory angina pectoris:Effect of enhanced external counterpulsation

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Journal of Geriatric Cardiology 2011年第4期8卷 215-223页

作者： Susanne M Bondesson Marie-Louise Edvinsson Thomas pettersson Lars Edvinsson Department of Medicine Kristianstad HospitalSE-29185 KristianstadSweden Department of Health Sciences Lund Lund UniversitySE-22100 LundSweden Department of Emergency Medicine Lund University HospitalSE-22185 LundSweden

Objective To examine if the skin microvascular bed is altered and can be modified by enhanced external counterpulsation(EECP)in patients with chronic refractory *** Twenty patients diagnosed with refractory angina were divided into EECP(n=10)or no EECP(n=10)*** data were compared to matched healthy subjects(n=20).The cutaneous forearm microvascular blood flow was measured by Laser-Doppler *** vascular responsiveness to iontophoretic administration of acetylcholine(ACh),sodium nitroprusside(SNP)and local skin warming were *** of Canadian Cardiovascular Society(CCS)-class,blood pressure and plasma samples were *** EECP patients showed reduced CCS-class compared to no EECP(P<0.05).Both EECP and no EECP(P<0.05)groups had decreased systolic blood pressure(SBP)as compared to SBP at baseline(P<0.05).There was no difference in resting blood flow between the two refractory groups at baseline as well as after EECP and seven weeks of *** to heating,the responses to ACh and SNP in the cutaneous microcirculation were lower in both groups of refractory angina patients as compared to healthy subjects(P<0.05).EECP patients corresponded positively to the treatment shown by reduced plasma level of soluble interleukin-2 receptor and *** Refractory angina patients have reduced responsiveness in their cutaneous microcirculation to ACh,SNP and heat compared to healthy *** EECP reduced the CCS-class,this effect was not associated with improvements in responsiveness of the cutaneous microcirculation.

关键词： refractory angina pectoris flowmetry microcirculation enhanced external counterpulsation

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Epidemic modeling:Diffusion approximation *** differential equations allowing reflection

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International Journal of Biomathematics 2021年第5期14卷 273-293页

作者： Mohamed El Fatini Mohammed Louriki Roger pettersson Zarife Zararsiz Laboratory of PDE’s Algebra and Spectral Geometry Department of MathematicsIbn Tofail University FSBP 133KénitraMorocco Mathematics Department Faculty of Sciences Semalalia Cadi Ayyad UniversityBoulevard Prince Moulay Abdellah P.O.Box 2390Marrakesh 40000Morocco Department of Mathematics Linneeus University 35195 VaxjoSweden Matematik Boliimu Nevgehir Had Bektag Veli Universitesi Turkey

A birth-death process is considered as an epidemic model with recovery and transmittance from *** fraction of infected individuals is for huge population sizes approximated by a solution of an ordinary differential equation taking values in[0,1].For intermediate size or semilarge populations,the fraction of infected individuals is approximated by a diffusion formulated as a stochastic differential *** diffusion approximation however needs to be killed at the boundary{0}U{1}.An alternative stochastic differential equation model is investigated which instead allows a more natural reflection at the boundary.

关键词： Epidemic models stochastic differential equations scale measure speed measure diffusion approximations reflecting boundaries killed processes

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Wildfire yields a distinct turnover of the beetle community in a semi-natural pine forest in northern Sweden

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Ecological Processes 2020年第1期9卷 505-516页

作者： Emelie Fredriksson Roger Mugerwa pettersson Jörgen Naalisvaara Therese Löfroth Wildlife Fishand Environmental studiesSwedish University of Agricultural SciencesSkogsmarksgränd 1790183 UmeåSweden County Administrative Board of Norrbotten Stationsgatan 597238 LuleåSweden

Background:Fires have been an important natural disturbance and pervasive evolutionary force in the boreal ***,fire suppression has made forest fires rare in the managed landscapes in Fennoscandia,causing significant habitat loss for saproxylic species such as polypores and *** better understand how the beetle community changes(species turnover)after a wildfire in a landscape with intense fire suppression,we monitored beetles with flight intercept traps the first 3 years as well as 12 years after a large wildfire in a national park in northern Sweden(a control/unburnt area was set up for the last year of sampling).Results:Species composition changed significantly among all studied years with a continuous turnover of species following the *** indicator species analysis showed that year 1 post-fire was mostly associated with cambium consumers and also the pyrophilous species Batrisodes *** 2 was the most abundant and species-rich year,with Tomicus piniperda as the most important indicator *** indicator species year 3 were mostly secondary successional species,fungivores,and predators and were characterized by lower species *** 12 had higher diversity compared with year 3 but lower species richness and abundance.A control area was established during year 12 post-fire,and our analyses showed that the control area and burned area differed in species composition suggesting that the beetle community needs longer than 12 years to recover even after a lowintensive ground ***:The wildfire area hosted several red-listed and fire-dependent species suggesting that after a century of landscape-level fire suppression in a semi-natural area,the reintroduction of fire benefits rare and pyrophilous species and still impacts species composition after 12 *** study implies that fire has long-lasting effects on high latitudes and that prescribed burning has the potential to benefit biodiversity over decades in these

关键词： Assemblage Boreal Coleoptera Species composition Conservation Disturbance Diversity Fire suppression Insects Protected area Saproxylic

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Media effects on the dynamics of a stochastic SIRI epidemic model with relapse and Lévy noise perturbation

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International Journal of Biomathematics 2019年第3期12卷 227-247页

作者： Badr-Eddine Berrhazi Mohamed El Fatini Roger pettersson Aziz Laaribi Department of Mathematics Ibn To fail University BP 133 Kenitra Morocco Department of Mathematics Linnaeus University 351 95 Vaxjo Sweden Poly disciplinary Faculty Sultan Moulay Slimane University BP 592 Beni Mellal Morocco

In this paper, we study the dynamic properties of an SIRI epidemic model incorporating media coverage, and stochastically perturbed by a Lévy noise. We establish the existence of a unique global positive solution. We investigate the dynamic properties of the solution around both disease-free and endemic equilibria points of the deterministic model depending on the basic reproduction number under some noise excitation. Furthermore, we present some numerical simulations to support the theoretical results.

关键词： Dynamics Lévy process white noisere lapse media coverage

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A stochastic threshold of a delayed epidemic model incorporating Levy processes with harmonic mean and vaccination

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International Journal of Biomathematics 2020年第7期13卷 297-323页

作者： Mohamed El Fatini Idriss Sekkak Aziz Laaribi Roger pettersson Kai Wang Laboratory of PDE’s Algebra and Spectral Geometry Faculty of SciencesIbn Tofail University BP 133KenitraMorocco Department of Mathematics Sultan Moulay Slimane University Beni MellalMorocco Department of Mathematics Linnaeus University 35195 VaxjoSweden Department of Applied Mathematics Anhui University of Finance and Economics Bengbu 233030 P.R.China

The aim of this paper is to investigate a stochastic threshold for a delayed epidemic model driven by Levy noise with a nonlinear incidence and ***,we derive a stochastic threshold 77s which depends on model parameters and stochastic coefficients for a better understanding of the dynamical spreading of the ***,we prove the well posedness of the ***,we study the extinction and the persistence of the disease according to the values of ***,using different scenarios of Tuberculosis disease in Morocco,we perform some numerical simulations to support the analytical results.

关键词： Dynamics Levy process delayed model stochastic threshold

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Liquid water structure from X-ray absorption and emission, NMR shielding and X-ray diffraction

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Science China(Physics,Mechanics & Astronomy) 2019年第10期62卷 68-81页

作者： Iurii Zhovtobriukh Benedito J.C.Cabral Carmelo Corsaro Domenico Mallamace Lars G.M.pettersson Department of Physics Stockholm UniversityAlbaNova University CenterStockholm SE-106 91Sweden University of Lisboa Faculty of SciencesBioISI-Biosysterns&Integrative Sciences InstituteLisboa 1749-016Portugal MI FT Department Messina UniversityMessina IT-98166Italy

Here we investigate to what extent X-ray absorption（XAS） and emission（XES） spectroscopy, the oxygen-oxygen radial distribution function and σ（1H） and σ(17O) NMR shielding can be represented by a common set of model structures of liquid water. This is done by using a Monte Carlo-based fitting technique which fits the spectra based on a library of ～1400 precomputed spectra and assigns weights to contributions from different model structures. These are then used to reweight the contributions from the structures in the library to reveal classes of structures that are over-or under-represented in the library. The goal is to include different experimental data sets which are sensitive to different aspects of liquid water structure and thus narrow down which types of structures must exist in the real liquid.

关键词： liquid water X-ray absorption X-ray emission NMR reverse Monte Carlo

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Sharing Knowledge： How to Highlight Proven Experience in the Swedish Armed Forces

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通讯和计算机（中英文版） 2011年第5期8卷 410-414页

作者： Ulrica pettersson Lund University Centre for Risk Assessment and Management Lund SE-221 00 Sweden Swedish National Defence College Department of Military Studies Stockholm SE-115 93 Sweden

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