A mathematical model representing temperature and moisture content in bread during baking is developed. The model employs the coupled partial differential equations proposed by Luikov. Dependences of mass and thermal properties of dough on temperature and moisture content are included in the model. Resulting system of non-linear partial differential equations in time and one space dimension is reduced to algebraic system by applying a finite difference numerical method. A numerical solution of the model equations is obtained and simultaneous heat and moisture transfer in dough during baking is predicted. The changes of temperature and moisture content during the time of the process are graphically presented and commented.

Abstract. The city of Ruse is situated in the north-eastern part of Bulgaria. The northern boundary of Ruse region goes along the Danube river valley and coincides with the state boundary of the Republic of Bulgaria and the Republic of Romania. The climate of the region of Ruse is temperate continental, characterized by cold winters and dry, warm summers. Spring and autumn are short.In our previous work we studied information from 40 years period measurements [6] of temperature, air humidity and atmospheric pressure in Ruse region, Bulgaria. It was shown that mean values of the temperature in Ruse region are slightly goes up for the last 10 years and they are bigger than the mean temperature for Bulgaria. This could be a proof for climate change in Ruse region of Bulgaria. The most variable atmospheric parameter is air humidity during the spring seasons. The hardest change of temperature and atmospheric pressure is during January. Temperature has biggest change in January and smallest -in July. Humidity has biggest change in April and smallest in October. Atmospheric pressure has biggest change in January and smallest in July [5]. Air pollution maybe affects temperature, atmospheric pressure and humidity. All this in our opinion may be a reason for the increase in average temperatures for the period examined.This paper is devoted to examine air pollution in the Ruse region. It presents a statistical analysis of the level of air pollution in Ruse on data from the monitoring stations in the city. The measurements cover the period from 2015 including up to now.For the most dangerous pollutant PM10 we create an ARIMA model which is in a good agreement with the PM10 measurements.

No abstract

No abstract

No abstract

No abstract

Abstract. The sources of dust on the territory of Ruse region, Bulgaria are industry, transport and domestic heating by solid fuel. PM10 (particulate matter with a diameter between 2.5 and 10 μm) levels for Ruse mark a significant increase during the autumnwinter period compared to the levels during the spring-summer period [1]. Obviously there is a relationship between PM10 contamination levels and ambient air temperature. The lower the temperatures are, the higher the PM10 levels are. The biggest peak of PM10 levels for the autumn-winter period is usually observed in January months. It is in January that the number of days in which there is exceedance of the limit values of the PM10 levels is maximum observed. Also in January months the day and night temperatures are the lowest and usually they do not pass 0°C for many days of the month. To understand better this relationship we provide a statistical analysis of ambient air PM10 contamination during winter periods. Correlations between the measured PM10 values and the respective temperatures measured for January months for different years are presented. Descriptive statistics of PM10 and some atmospheric characteristics as well as linear regression analysis are calculated and commented in the paper.

No abstract