International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

In the development of new composite structural elements based on sedimentary rocks (clays) as inorganic binders and foam composite materials, their physical characteristics are presented for the construction of recipe compositions and the determination of their complex new properties. The role of the components of the compositions, together with organic reinforcing fiber materials such as straw, rice husks and others, basic parameters of the technological regime and other factors for ensuring adequate workability of the prepared composite compositions for obtaining building coatings and elements – bricks and panels for building ecological houses – is considered. The determination of the necessary technological characteristics of the composite mixtures ensures their effectiveness.

A brief review of the design characteristics of the main construction types of standard movable frame and traditional beehives applicable in beekeeping farms is presented. The performance of a newly developed innovative movable frame beehive constructed of durable, heat-resistant hollow chamber ceramic structural elements is discussed. A comparison of the functional characteristics of prepared experimental ceramic hive prototypes and the prevailing types of standard beehives made of other materials is carried out. The existing requirements and prospects for equipping beekeeping farms with ceramic hives providing prolonged service life, higher yields and increased sustainability in diverse climatic environments and critical conditions are analysed.

In laboratory conditions, the frost resistance of hollow ceramic samples (constructive elements of ceramic beehives) was examined by applying a standardized methodology for assessing the reliability of ceramic products. For both sample types that were investigated (each with different phase compositions), the result for the frost resistance coefficient Kfr is above 84%. The products retain their structural integrity and high resistance in an extreme temperature environment. It was not observed any significant damage that could disrupt their functionality. The obtained results prove the assumptions that the ceramic beehives are appropriate for use in vast geographical regions characterized by critical temperatures and high diurnal and seasonal temperature amplitudes. At the same time, the experimental data can serve for further optimization of the recipe compositions, the technological regime, and for improvements of the construction characteristics of the ceramic elements that build the ceramic beehive.

An original installation and method for the preparation of ash with a predominant content of amorphous SiO2 (96-97 %), which is a technological residue after thermal treatment of agro-biological waste (rice husks), are presented. The resulting product is a complete raw material for the production of materials with a variety of functional characteristics, using different technological designs (in combination with other components). The design parameters of the installation and the different stages of the developed technological approach are discussed. The basic operating mode of the installation within one operating cycle is presented. The design features and technical equipment of the installation allow controlled creation, maintenance and modification of the necessary technological conditions for the effective thermal processing of the waste biomass.

An innovative device and a cost-effective and environmentally friendly technology have been developed to produce porous composite materials by using two types of waste raw materials: residual biomass from agricultural production and municipal waste. Heattreated rice husk and ground waste glass were used as main components. The technological approach presented here allows for the preparation of “breathable” porous materials with the predominant presence of open pores and increased specific surface area. A promising possibility for the application of the developed materials is their use in bulk or in the preparation of various composite building elements based on inorganic binders. Recipes and an adequate technological regime have been developed taking into account the design characteristics of the production facility, the specificity of the waste raw materials used and the intended target performance of the products.

The technological characteristics of suspensions used in the development of new thermal insulation composite structural elements based on foam materials and inorganic binders (Portland cement) are investigated. The role of the components of the compositions, the parameters of the technological regime and other factors in ensuring adequate workability of the prepared cementitious solutions is considered. Determination of the necessary technological characteristics of composite mixtures ensures their effective distribution in the formwork moulds when forming the specimens, cost-effective performance at production stage and obtaining products with the planned
functional properties. The existing opportunities for potential application in modern construction of the developed composite elements are analyzed.

Prototypes of an innovative collapsible beehive, built of long-lasting, structural elements of quartz ceramics with high atmospheric resistance and the presence of air cavities with thermal insulation properties, were prepared. Prescription compositions, an original set of molds, and an adequate heat treatment regime applicable to obtain the structural details were developed. The role of the various technological factors in the formation of the performance indicators of the end products was analyzed. The main characteristics of the prepared experimental prototypes and their major functional advantages in comparison with the existing standard and traditional hives were observed. The presented innovative beehive provides a favorable natural habitat for the normal and safe development of bee families and allows the full application of modern approaches for the efficient and ecological production of high-quality natural apian products.

An observation of the current state of the beekeeping industry and the prevailing main problems was carried out. The prospects for increasing the efficiency and functional capabilities of the bee farms were analyzed. According to the long-term research activity, a technological regulation was contrived for producing innovative ceramic hives. The development is superior to the existing standard beehives made of other materials, in terms of complex operational indicators. The phase composition and technical characteristics of obtained samples of marl raw material (from Bulgarian deposits) were investigated, potentially applicable for the production of various
modifications of ceramic collapsible hives.

A solution was synthesized in a system ZrO2-CeO2 by sol-gel synthesis and deposited by the immersion method. The pretreated Nb substrate was treated with sulfuric acid and absolute alcohol solutions. Layering was in three stages. The sample was heat treated at 500°C. The obtained results are characterized by XRD, XPS, CEM analyzes.

The development refers to an innovative technology and technological scheme of a workshop for the production of beehives made of amorphous quartz ceramics. The conditions for obtaining stable suspensions from quartz glass are emphasized and investigated. The time for the treatment of the glass in the grinding device, the amount of water, the influence of the modifiers in stabilizing the suspension by adjusting the pH level, as well as the most suitable sedimentary composition of the glass particles are established. The factors determining the speed and degree of sintering of the ceramics are investigated and established. They include the density of the raw products, the dispersion of the quartz glass particles and its purity, as well as the environment in the furnace and the sintering mode.

The aim of this paper is to review the cleaning of solar photovoltaic (PV) systems and applied coatings that eliminates costly automated cleaning systems by using nano-sized TiO2 combined with various organic binders.

The research is related to the creation of new compounding formulations for the production of “yellow” paving stones. This was necessary due to denied access to a potential source of suitable raw material from the deposit near the village of Svetlen, Popovo municipality. Marlstone raw material from this deposit has the necessary qualities for such production, as a result of which, after hightemperature liquid-phase synthesis, new petrurgic phases with high physicochemical and mechanical properties can be formed. The new compounding formulation of the molding mass was developed on the basis of marlstone sedimentary rock from the Alexandra deposit, located near the village of Lovets, Targovishte district. The use of this compounding formulation makes it possible to obtain appropriate physicochemical and mechanical properties and a yellow coloring equivalent to that of the reference samples.