ALGORITHM OF CONTROLLING AN ADAPTIVE HYDRAULIC CIRCUIT FOR MOBILE MACHINES

Hydraulic systems based on adjustable pumps, proportional electrohydraulic equipment and controllers are used in mobile machines. The authors propose a new scheme of the hydraulic system for mobile machines, which provides the auger drilling operation. A number of studies have shown that a certain ratio should be maintained between the frequency of auger rotation and its feed during operation, where the productivity of soil disruption should not exceed the productivity of transporting loose soil from the drilling zone. Ensuring the required ratio between the speed of the auger rotation and its feed is implemented by a controller that works according to a certain algorithm. A nonlinear mathematical model of the hydraulic system was developed to create the algorithm for controller operation and setting. The equations of the mathematical model are solved in the MATLAB-Simulink environment by the Rosenbrock method. As a result of solving the equations for the mathematical model, the dependences of variables describing the state of the hydraulic system on time are obtained. The values of the controller settings are determined at which the hydraulic system works steadily, the error of flow rate stabilization, the time for pressure adjustment and readjustment does not exceed the allowable values. The algorithm for controlling the auger feed value is formed. This algorithm provides the necessary ratio between the auger feed and speed, as well as reducing the feed rate in the case of soil hardness increases. This creates the conditions for uninterrupted pit drilling at full depth and protection of the hydraulic system from overload.

GUNITECH®: An Innovative Pumice Based Dry Shotcrete Application

Pumice quarried by LAVA MINING AND QUARRYING SA from Yali Island, Dodecanese, is used in domestic and foreign markets mainly as concrete lightweight aggregate, masonry unit constituents, road substrate, and loose soil stabilization. It is a porous natural volcanic rock with low density, low thermal and noise transmission, and the highest strength among all the natural or artificial lightweight materials of mineral origin. Nowadays, pumice is of additional interest as it has a reduced CO2 footprint because thermal energy is not needed for its expansion compared with the artificial lightweight aggregates. In this context, HERACLES GROUP in collaboration with Sika Hellas has launched a new product containing pumice stone under the brand name GUNITECH®. GUNITECH® is an innovative bagged material for spraying concrete applications. It is a ready lightweight concrete, for building repairs certified as EN 1504-3.

Assessment of soil compacted state in forest road costruction

The issue of soil compacted state forecasting during the construction of a forest road is considered. The mechanical system formation of contacting particles of the compacted soil are given and substantiated. A model of compaction of a loose soil layer in the system "compaction device - compacted material" has been developed. A new compartment approach in this field of applied research was used, within which the system under study is subdivided into interconnected units, called compartments, the content of a certain substance in each of them is a separate variable of the system. Various technological situations are analyzed with the minimum and maximum allowable boom outreach of the excavator. The modeling of the effect of porosity on the soil layer thickness during its compaction, denser packing of particles and the appearance of residual (irreversible) deformations has been carried out. A method for determining the relationship between the degree of soil compaction and changes in its porosity and deformations has been developed. The complexity of the theoretical study of the compacted soil is substantiated. The practical significance of the developed model of soil layer compaction and the methodology for assessing its deformations has been confirmed with successful implementation at the design and monitoring stages of the construction of a pilot section of a forest road located in the Republic of Karelia on the basis of Petrozavodsk State University.

An unusual body colouration of Ceylon roughside snake (Aspidura ceylonensis)

The small sized, non-venomous, and fossorial colubrid snake genus Aspidura Wagler, 1830 is endemic to Sri Lanka. Aspidura ceylonensis (Günther, 1858) is rare and restricted to mid-elevation to montane and sub-montane forests at elevation of 500–1300 m a.s.l. in the Central Highlands and the Knuckles massif. It is found in cool and well-shaded forest areas, with thick moist leaflitter, woody debris, and loose soil. The usual adult body coloration on dorsum is dark reddish or dark orange, rarely yellowish, with a continuous black vertebral line and two rows of dorsolateral black spots along the body.

Main Problems Using DEM Modeling to Evaluate the Loose Soil Collection by Conceptual Machine as a Background for Future Extraterrestrial Regolith Harvesting DEM Models

Nowadays, rapid product development is a key factor influencing a company’s success. In the Space 4.0. era, an integrated approach with the use of 3D printing and DEM modeling can be particularly effective in the development of technologies related to space mining. Unfortunately, both 3D printing and DEM modeling are not without flaws. This article shows the possibilities and problems resulting from the use of DEM simulation and 3D printing simultaneously in the rapid development of a hypothetical mining machine. For the subsequent development of the regolith harvesting model, loose soil harvesting simulations were performed and the underlying problems were defined and discussed. The results show that it is possible to use both technologies simultaneously to be able to effectively and accurately model the behavior of this type of machine in various gravitational conditions in the future.

Geotechnical parameter study and solidification of Marine Sediment for Road Engineering

The Chinese coastal areas are the environment of multiple activities, and navigation occupies an important place. Dredging operations maintain access to port structures carried out regularly. These sediments’ fate is problematic in Jiangsu province due to significant contamination of organic and mineral pollutants. A company called Nature Way aims to solve this problem. It is deeply committed to the treatment and use of sediment dredged from the seabed and uses proprietary solidification technology to transform all kinds of silt waste into new engineered materials that replace sand and sand. Gravel and traditional techniques and can be used as foundation materials for various projects in loose soil areas. In this work, we first studied the physic-chemical characterization of raw materials sediments supplied by Nature Way Corporation from Jiangsu province. Secondly, we have to mix the raw sediment and the solidifying agents and test the mechanical performance at 3%, 5% and 7% in a time interval of 7 days, 14 days, and 28 days. Finally, we have to measure the (CBR) “California Bearing Ratio” after 28 days, mix with the binder at 3%, 5%, 7%.

ON THE QUESTION OF EXISTENCE AND APPEARANCE AN ANCIENT RUS` CHURCH OF ASCENSION IN PEREMYSHL (PRZEMIŚL)

Architectural and urban organization of Przemyśl in the era of Kievan Rus' remains a little-studied topic. Significant changes that city has undergone throughout history have almost completely leveled the spatial structure of the first centuries of its history, when it was the capital, and later, the second most important city in Halician Rus'. One of the few covered topics are the identification and localization of religious buildings of the X-XIV centuries. Sometimes, data about them is obtained from small crumbs of information preserved in medieval sources, as well as in archaeological materials. The articles summarize the sources and archaeological materials about probable existence of ancient Rus` Ascension church on so-called "Tatar Hill" in Przemyśl. On their basis it provides arguments on this hypotheses. Such arguments are: onomastic (historical dominance of the name of the Ascension and its derivatives in the area), necropolic (presence of traces of the churchyard), ritualistic (ancient tradition of religious processions that ended here), conversionalistic (existence here in the XVI - XVII centuries roman-catholic chapel of St. Leonard may be associated with the practice of transformation of Latin temples from old Rus` ones). Additionally, it is supported by the practice of building rocky-wooden objects in Нalician Rus', a number of which were discovered in the second half of the twentieth century. Due to the exceptional location of the hill in terms of survey of the area and archaeological material, it was suggested a military nature of its use. However, in all the archaeological research conducted here since the nineteenth (and possibly eighteenth centuries), no object of military purpose has been found. This is a stark contrast, for example, to the archeological material found on Stare Zamchysko Hill (or the hill of the Three Crosses), one kilometer to the north-west. Probable structure of the Ascension Hill in ancient Rus` times can be outlined as such. The church could be part of a small monastery complex and was located on the highest rock from the west. The rock was partially covered with earth to eliminate cracks and level the surface. Further to the east there was a reduction, on which, on the loose soil, there were living quarters. The complex could protect the fence, both at the top and around the hill.

Leaf-cutting ant (Atta laevigata Smith) in an African mahogany plantation in Minas Gerais state, Brazil

Khaya grandifoliola C. DC. (Meliaceae), known as African mahogany, is used in the establishment of commercial plantations for high-value timber production. This work aims to report the first occurrence of the genus Atta in a commercial plantation of this species. An ant nest mound with 105 m2 of loose soil and five active ant holes were observed. Leaves cut into crescent shaped sections and pieces of young branches were found near these holes, in addition to trees with the apical part of their crown partially defoliated. The collected specimens were identified as Atta laevigata Smith (Hymenoptera: Formicidae: Attini), locally known as the glass-head leaf-cutting ant.

Ant diversity sampling in the Brazilian Amazon: a comparison of litter collection and pitfall trapping

Introduction: Ants in tropical forests are a hyper-diverse group that plays important ecological roles. Several studies on tropical forests have used different sampling protocols to capture soil ants, making it difficult to compare responses and patterns of diversity between studies. Thus, research that compares different well-structured and standardized sampling methodologies to adequately estimate the richness of ant species in tropical forests is necessary. Objective: In this study, we examined the combination of catches with pitfall traps with and without baits and litter collections for soil ant sampling. Methods: In the fall traps, we use two baited (sardines and bananas) and one non-baited. For the manual collections (litter sampling), the litter and only the topsoil of the loose soil were collected. Results: We found that traps containing sardine baits collected a greater abundance of ants, whereas non-baited traps collected a greater richness of ant species. On the other hand, litter collections captured the largest number of exclusive species, presenting a different species composition from the pitfall traps (with and without baits). In general, baited traps showed greater abundance in more degraded locations, while manual collections and unbaited pitfalls captured more individuals in preserved environments. Conclusions: Our results provide evidence that, for accurate sampling of soil ant assemblages in tropical forests, the use of different methodologies is necessary to capture a greater diversity of species because the methods differ in effectiveness according to habitat.