We discuss deductions that can be made as to the stability of multispecies communities, knowing only the structure of the food web, i.e., knowing only the signs of the elements in the interaction matrix. Systems which are stable in these circumstances are called qualitatively stable and have been treated in economic and other contexts. The discussion touches upon general aspects of the relation...

A qualitative model of the spatio-temporal behaviour of distributed parameter systems based on physical fields is presented. Field-based models differ from the object-based models normally used in qualitative physics by treating parameters as continuous entities instead of as attributes of discrete objects. This is especially suitable for natural physical systems, e.g. in ecology. The model is ...

 In today’s highly competitive market, the pressure on organizations to find a better way to create and deliver value to customers is mounting. The decision involves many quantitative and qualitative factors that may be conflicting in nature. Here, we present a new model for transportation problem with consideration of quantitative and qualitative data. In the model, we quantify the qua...

The goal of this study is to estimate the cloud radiative feedback effect on the annual variation of the global mean surface temperature using radiative flux data from the Earth Radiation Budget Experiment. We found that the influence of the cloud feedback upon the change of the global mean surface temperature is quite small, though the increase of the temperature is as much as 3.3 K from Janua...

This paper presents a comparative analysis of the productive efficiency of two types of firms in China --foreign-invested enterprises (FIEs) and state-owned enterprises (SOEs), using a stochastic frontier production function model and the latest statistical data (1993-97). It has found that the FIEs in general outperformed SOEs in productive efficiency, as demonstrated by the differentials in t...

Analogous to the identification of continuous dynamical systems, identification of discrete-event systems DESs consists of determining the mathematical model that describes the behaviour of a given ill-known or eventually unknown system from the observation of the evolution of its inputs and outputs. First, the paper overviews identification approaches of DES found in the literature, and then i...

Background: The rapid development of the blockchain technology and its various applications has rendered it important to understand the guidelines for adopting it. Methods: The comparative analysis method is used to analyze different dimensions of the maturity model, which is mainly based on the commonly used capability maturity model. Results: The blockchain maturity model and its adoption pro...

With systems for acquiring 3D surface data being evermore commonplace, it has become important to reliably extract specific shapes from the acquired data. In the presence of noise and occlusions, this can be done through the use of statistical shape models, which are learned from databases of clean examples of the shape in question. In this paper, we review, analyze and compare different statis...

The article is devoted to the comparative analysis of software packages in financial time series modeling. The most common among economists packages R, Eviews and Gretl are considered. Volatility is often used as a rough approximation to measuring of overall risk financial instruments. Polish stock index WIG for the modeling of financial time series volatility was chosen. Econometric model of f...

A comparative analysis of different models of a Magneto-Rheological (MR) damper was done. Three models were tested: a non-linear ARX, a semi-phenomenological and a phenomenological. Although the non-linear ARX model shown the best result, this is a black-box model with limited use. However, the Semi-Phenomenological model represented an excellent option considering the physical meaning of its p...