Geodesic measurements of mining area deformations indicate that their description fails to be regular,

as opposed to what the predictions based on the relationships of the geometric-integral theory suggest.

The Knothe theory, most commonly applied in that case, considers such parameters as the exploitation

coefficient a and the angle of the main influences range tgβ, describing the geomechanical properties of the

medium, as well as the mining conditions. The study shows that the values of the parameters a = 0.8 and

tgβ = 2.0, most commonly adopted for the prediction of surface deformation, are not entirely adequate in

describing each and every mining situation in the analysed rock mass. Therefore, the paper aims to propose

methodology for determining the value of exploitation coefficient a, which allows to predict the values

of surface subsidence caused by underground coal mining with roof caving, depending on geological and

mining conditions. The characteristics of the analysed areas show that the following factors affect surface

subsidence: thickness of overburden, type of overburden strata, type of Carboniferous strata, rock mass

disturbance and depth of exploitation. These factors may allow to determine the exploitation coefficient a,

used in the Knothe theory for surface deformation prediction.

An analysis of the impact of mining with caving on the surface shows that a type of rock mass strata seems to be one of the critical factors affecting the process. Correlating the values of mining-induced surface deformation with the rock mass structure and the state of its disturbance is of crucial importance. Therefore, if other mining conditions are left unaffected, then those factors exert the key influence on a course and distribution of subsidence and rock mass deformation. A proper description of rock mass type and properties also seems rational for a proper determination of prediction parameters, especially in the case of a multi-seam coal mining, and/or the exploitation carried out at considerable depths. A general outcome of the study discussed in this paper is the development of the methodology and model practices for determining the rock mass type and, as a result, for selecting the optimal values of parameters for predicting the values of surface subsidence in relation to particular geological and mining conditions. The study proves that the type of rock mass may be described by such factors as the influence of overburden strata, the influence of Carboniferous layers, the disturbance of rock mass and the depth of exploitation.

The aim of this article is to assess the potential of converting gasoline-powered passenger cars into electric vehicles in Poland. Based on the available literature data, the vehicle structure was classified using the following criteria: vehicle age, engine capacity, car segment, type of fuel used, and curb weight. The average fuel and electric energy consumption values per vehicle before and after conversion were determined using specially developed statistical models. The conversion and operation costs of a conventionally fueled vehicle and an electric vehicle (after conversion) were estimated using a stochastic simulation model employing probability density distributions of vehicle parameters and the Monte Carlo method. Vehicle parameters were estimated to reflect the real structure of passenger cars in Poland. The estimated costs of converting a gasoline-powered vehicle to an electric vehicle (including the purchase and installation of an electric motor and battery) and its subsequent operating costs enabled the assessment of the economic efficiency of the car conversion process. The potential for converting gasoline-powered cars to electric vehicles was estimated by comparing the operating costs of the vehicle before and after conversion, taking into account the costs of the conversion itself. The potential of the studied conversion process amounted to 535,000 vehicles, which would generate an annual electricity demand of 1,746.36 GWh with electricity prices of 0.6 PLN/kWh. The conversion is economically viable mainly in passenger cars with a spark engine (more than 90% of cases).