Modeling of cometary evolution by kinetic theory: Method and first results

Physical evolution of Jupiter family (JF) comets is considered as a simultaneous process of erosion and fading. Dynamical effects are limited to discrete changes of the perihelion distance, that result in changes of the evaporation rate. Assuming that the JF comet population is in a steady state, a distribution function of this population in the two dimensional phase space consisting of radius and active fraction of the nucleus surface is found as the solution of a set of kinetic equations, each one of them for a different perihelion distance. With use of the distribution function some statistical properties of the comet population, like the total number of comets in the considered region of the phase space, the number of objects that evaporate or get dormant per unit time, etc., are obtained. The cumulative distribution function with respect to the absolute brightness is calculated and compared with the observed one as a check on the considered models.     

Thermal treatment of waste from the meat industry in high scale rotary kiln

Recently there has been an increase in consumption of meat, especially poultry. This results in an increase in the quantity of waste, including waste feathers. Waste from the meat industry are hazardous, which must be disposed of in accordance with the law. Wastes from the meat industry normally consist of valuable elements such as phosphorus, calcium, potassium, magnesium (macronutrients), and iron, copper, zinc, manganese (micronutrients), which after suitable processing can be used for the purposes of fertilization. The paper presents the results of thermal treatment of feathers with meat and bone meal and feathers with poultry litter in a high scale rotary kiln. Mixtures of wastes were incinerated in temperature range from 600 to 900 °C for about 20–25 min. The resulting ashes were characterized by a high content of phosphorus (4–17%), calcium (17–30%) and potassium (0.6–3.6%). The study revealed that the selection of process parameters allows for obtaining ash with controlled and desired composition of macro and micronutrients, moreover, it is safe in terms of sanitary.     

Hoarfrost and rime chemistry in Poland—An introductory analysis from meteorological perspective

Hoarfrost and rime analysis was based on the collection of samples between 2003 and 2006 from 8 sites, which represent both lowland (northern) and mountainous (southern) parts of Poland. On the other hand 4 of these sites belong to “urban” and 4 to “rural” category. pH, conductivity, SO₄²⁻, NO₃⁻, Cl⁻, H⁺, NH₄⁺, Ca²⁺, Mg²⁺, Na⁺, K⁺ have been determined in order to study the chemistry of hoarfrost and rime. Higher total inorganic ionic content (TIC) in hoarfrost and rime (2.46 meq·l⁻¹ and 1.23 meq·l⁻¹ respectively) was observed when compared with precipitation (0.37 meq·l⁻¹). Large variability of TIC and chemical composition of individual samples were typical at each of the measurement sites depending on emission patterns, atmospheric conditions and local terrain topography. Higher concentrations of both hoarfrost and rime occurred in southern (mountainous) rather than in northern (lowland) part of Poland which can be explained by worse pollutant dispersion conditions in the south. The surprisingly low hoarfrost concentrations in urban coastal stations in the area of the Bay of Gdansk were attributed to the cleaning effect of nocturnal breeze-type circulation, best pronounced in cool part of the year. Due to relatively high pollutant concentration and long duration, hoarfrost and rime are at least significant factors in environmental processes in different ecosystems in Poland.     

Cooling curves and initial models for low-mass white dwarfs (<0.25 M⊙) with helium cores

We present a detailed calculation of the evolution of low-mass (<0.25 M_⊙) helium white dwarfs. These white dwarfs (the optical companions to binary millisecond pulsars) are formed via long-term, low-mass binary evolution. After detachment from the Roche lobe, the hot helium cores have a rather thick hydrogen layer with mass between 0.01 and 0.06 M_⊙. As a result of mixing between the core and outer envelope, the surface hydrogen content ( X _surf) is 0.5–0.35 , depending on the initial value of the heavy element Z and the initial secondary mass. We found that the majority of our computed models experience one or two hydrogen shell flashes. We found that the mass of the helium dwarf in which the hydrogen shell flash occurs depends on the chemical composition. The minimum helium white dwarf mass in which a hydrogen flash takes place is 0.213 M_⊙ ( Z =0.003), 0.198 M_⊙ ( Z =0.01), 0.192 M_⊙ ( Z =0.02) or 0.183 M_⊙ ( Z =0.03). The duration of the flashes (independent of chemical composition) is between a few ×10⁶ and a few ×10⁷ yr. In several flashes the white dwarf radius will increase so much that it forces the model to fill its Roche lobe again. Our calculations show that the cooling history of the helium white dwarf depends dramatically on the thickness of the hydrogen layer. We show that the transition from a cooling white dwarf with a temporarily stable hydrogen-burning shell to a cooling white dwarf in which almost all residual hydrogen is lost in a few thermal flashes (via Roche lobe overflow) occurs between 0.183 and 0.213 M_⊙ (depending on the heavy element value).     

Lithospheric structure of the Trans-European Suture Zone along the TTZ–CEL03 seismic transect (from NW to SE Poland)

The large-scale CELEBRATION 2000 seismic experiment investigated the velocity structure of the crust and upper mantle between western portion of the East European Craton (EEC) and the eastern Alps. This area comprises: the Trans-European Suture Zone, the Carpathian Mountains, the Pannonian Basin and the Bohemian Massif. This experiment included 147 chemical shots recorded by 1230 seismic stations during two deployments. Good quality data along 16 main and a few additional profiles were recorded. One of them, profile CEL03, was located in southeastern Poland and was laid out as a prolongation of the TTZ profile performed in 1993. This paper focuses on the joint interpretation of seismic data along the NW–SE trending TTZ–CEL03 transect, located in the central portion of the Trans-European Suture Zone. First arrivals and later phases of waves reflected/refracted in the crust and upper mantle were interpreted using two-dimensional tomographic inversion and ray-tracing techniques. This modelling established a 2-D (quasi 3-D) P-wave velocity lithospheric model. Four crustal units were identified along the transect. From northwest to southeast, thickness of the crust varies from 35 km in the Pomeranian Unit (NW) to 40 km in the Kuiavian Unit, to 50 km in the Radom–Łysogóry Unit and again to 43 km in the Narol Unit (SE). The first two units are thought to be proximal terranes detached from the EEC farther to the southeast and re-accreted to the edge of the EEC during the Early Palaeozoic. The origin of the remaining two units is a matter of dispute: they are either portions of the EEC or other proximal terranes. In the area of the Polish Basin (first two units), the P-wave velocity is very low (V_p < 6.1 km/s) down to depths of 15–20 km indicating that a very thick sedimentary and possibly volcanic rock sequence, whose lower portion may be metamorphosed, is present. The velocity beneath the Moho was found to be rather high, being 8.25 km/s in the northwestern portion of the transect, 8.4 km/s in the central sector, and 8.1 km/s in the southeastern sector.     

A water-budget approach to restoring a sedge fen affected by diking and ditching

A vast, ground-water-supported sedge fen in the Upper Peninsula of Michigan, USA was ditched in the early 1900 s in a failed attempt to promote agriculture. Dikes were later constructed to impound seasonal sheet surface flows for waterfowl management. The US Fish and Wildlife Service, which now manages the wetland as part of Seney National Wildlife Refuge, sought to redirect water flows from impounded C-3 Pool to reduce erosion in downstream Walsh Ditch, reduce ground-water losses into the ditch, and restore sheet flows of surface water to the peatland. A water budget was developed for C-3 Pool, which serves as the central receiving and distribution body for water in the affected wetland. Surface-water inflows and outflows were measured in associated ditches and natural creeks, ground-water flows were estimated using a network of wells and piezometers, and precipitation and evaporation/evapotranspiration components were estimated using local meteorological data. Water budgets for the 1999 springtime peak flow period and the 1999 water year were used to estimate required releases of water from C-3 Pool via outlets other than Walsh Ditch and to guide other restoration activities. Refuge managers subsequently used these results to guide restoration efforts, including construction of earthen dams in Walsh Ditch upslope from the pool to stop surface flow, installation of new water-control structures to redirect surface water to sheet flow and natural creek channels, planning seasonal releases from C-3 Pool to avoid erosion in natural channels, stopping flow in downslope Walsh Ditch to reduce erosion, and using constructed earthen dams and natural beaver dams to flood the ditch channel below C-3 Pool. Interactions between ground water and surface water are critical for maintaining ecosystem processes in many wetlands, and management actions directed at restoring either ground- or surface-water flow patterns often affect both of these components of the water budget. This approach could thus prove useful in guiding restoration efforts in many hydrologically altered and managed wetlands worldwide.