A BIOLOGICALLY MEANINGFUL PROBABILITY DESCRIPTION OF PLANKTON STOCKS

Plankton standing stocks can be described with a gamma probability distribution based on a stochastic logistic equation. The stock is characterized by a carrying capacity and a randomness coefficient.

Wave Steepness and Rogue Waves in the Changing Climate in the North Atlantic

Wave steepness is an important parameter not only for design and operations of marine structures but also for statistics of surface elevation as well as occurrence of rogue waves. The present study investigates potential changes of wave steepness in the future wave climate in the North Atlantic. The Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) uses four scenarios for future greenhouse gas concentrations in the atmosphere called Representative Concentration Pathways (RCP). Two of these scenarios with radiative forcing of 4.5 and 8.5 W/m2 by the end of the 21st century have been selected to project wave conditions in the North Atlantic. The analysis includes total sea, wind sea and swell. Changes of wave steepness for these wave systems are shown and compared with wave steepness derived from historical data. Long-term probability description of wave steepness variations is proposed. Consequences of changes in wave steepness for statistics of surface elevation and generation of rogue waves are demonstrated. Uncertainties associated with wave steepness projections are discussed.

Modernitet, sannhet og sannsynlighet. Samfunnets temporalisering av kunnskap

Det moderne samfunnets kunnskap bygger i stor grad på sannsynlighet – beskrivelser av sannsynlig realitet, men hva baseres en slik kunnskap på, hva er dens referanse og hva betyr den for samfunnet? Slike beskrivelser viser til en fremtidig realitet, altså til noe som ikke eksisterer. Deres sannhetsverdi kan derfor ikke bestemmes, og deres realitet må derfor ligge i beskrivelsen. Som beskrivelser er de realitet. Hvis vi tenker konstruktivistisk lar det seg gjøre å gi en plausibel bestemmelse av begrepet ”sannsynlig realitet”. Vi må også relatere begrepet til det moderne samfunnets temporalstruktur, først og fremst dets omgang med dens ukjente, men åpne og kontingente fremtid. ENGELSK ABSTRACT: Sverre Moe: Modernity, Truth and Probability: Society’s Temporal Structure of Knowledge Knowledge in modern society is based, to a considerable extent, on probability, on descriptions of probable reality. But what is such knowledge based on, what is its reference point and what does this reference point mean for society? Descriptions of probable reality refer to a future reality, something that does not yet exist and which cannot be certain to come about. The value of these probabilities is therefore indecisive, and hence their “reality” must be found in the probability description as such. As descriptions such probabilities are real. The concept of “probable reality” can be plausibly defined if we think in constructivist terms. We must also relate this concept to the temporal structure of modern society, in particular to its handling of its unknown, but open and contingent future. Key words: Probability, knowledge, temporality, constructivism, decisions.

An Application of Fuzzy Fault Tree Analysis for Large and Medium-Sized Pumping Stations

Risk analysis for large and medium-sized pumping stations was conducted by using the theory of fault tree. Model was established for fault tree analysis on running risk of pumping stations. Structural importance of minimal cut sets was analyzed and compared on the magnitude based on the probability description of fault tree given. Then the major influencing factors were identified and risk rating of pumping stations was discussed. In addition, appropriate countermeasures were provided for management. And application example was given.