In this study, vegetation coverage changes over a 30-year period for the Tuy Duc and Dak R’lap districts, Dak Nong province (central highland of Vietnam) were assessed using remote sensing and Geographic Information Systems (GIS) techniques. 03 Landsat satellite images, including Landsat TM February 13, 1990, Landsat TM February 22, 2005 and Landsat 8 January, 15 2020 were used to calculate the normalized difference vegetation index (NDVI), then assessed the changes in vegetation coverage density. The NDVI differencing method is also used as a change detection method and provides detailed information for monitoring changes in land cover in periods 1990 – 2005, 2005 – 2020 and 1990 – 2020. Analysis of the obtained results showed that the vegetation coverage declined sharply during 1990 – 2005 period, then the vegetation coverage has begun to recover in period 2005 – 2020. From the findings of this study, it can be easily concluded that the Tuy Duc and Dak R’lap areas has lost its valuable vegetation cover both qualitatively and quantitatively.
The research object. The hydrological characteristics of the Gunt and Vanch rivers belonging to the Southwestern and Central climatic zones of the Pamirs and are tributaries of the transboundary Pyanj River are considered. Long-term average values of temperature and precipitation as the main factors affecting the formation of river flows are determined for the period 1944–2016. The state of glaciation in the basins of the respective rivers is estimated. Goal. A comparative assessment of the influence of climatic features and mountain orography on the formation of river flows. Determination of the trend of changes in the climatic conditions of the Gunt and Vanch river basins at different periods of more than 70 years (1944–2016). Research methods. Generalization, systematization of meteorological and hydrological characteristics and determination of their change compared with the base period 1960–1990. Statistical processing of meteorological and hydrological data and establishing a trend of changes in climatic and hydrological characteristics using a differentiated method. Research results. It is shown that the nature of changes in hydrological characteristics, namely the flow of rivers in different climatic zones of the Pamir can differ significantly. On the example of two rivers (Gunt and Vanch) - tributaries of the transboundary Pyanj river, it is shown that the trend of change in the flow of the Gunt river differs from the Vanch river due to the state of glaciation of the river basin. To explain the results the meteorological conditions of the respective river basins and their possible impact on river hydrology were studied. Conclusion. The hydrological characteristics of the Gunt and Vanch rivers in the Pamirs taking into account the meteorological conditions of the respective river basins show that a key factor in improving the state of glaciation and reducing degradation processes, as well as achieving positive trends in the mass balance of glaciers is the presence of sufficient air mass in the glaciation zone. Naturally, this is the key to ensuring a sufficient amount of runoff.
This study discusses particularly the perception of three stockholders regarding the physical effects of second home tourism in rural Iran. The study seeks to examine the perceptions of second home tourism within local communities; on the base of a sustainable development approach. The research has been done on the base of descriptive and exploratory methods. Sample of 120 individuals (residents and tourists) were selected by using a stratified random method. Besides, all local administrators that were 6 people participated in interviews and they completed the questionnaires. The validity data of questionnaire was 0.8 which is reliable. For analyzing the data we used descriptive methods by SPSS software. The findings show that second home tourism, particularly in mountainous areas, can lead to unsustainability by leaving negative effects on the physical environment of villages, so applying the land use zoning strategy and design the guidelines for sustainable development can be useful to achieve rural sustainable development.
The purpose of research in the extraction of minerals is the development of technologies that will make it possible to drill wells specially designed for the extraction of ores with a length of several kilometers and a diameter of 300 mm to 2 m. The main research method is an experiment, during which drilling of wells by alternative methods under the same conditions is compared according to a single the selected performance criterion. Drilling of wells with an average length of 1500 meters with an end diameter of 295 mm at a depth of 200 to 400 meters was carried out in soft rocky ground in two alternative ways. The productivity of a directional drilling rig is determined by the efficiency of related interconnected processes, the correlation of which is characterized by graphs, for example, the dependence of the load on the bit on the drilling speed. To calculate the load on the drill pipe, Young’s modulus and the moment of inertia of its section were used. The axial force for drilling the well is determined by calculation using experimental data. By modeling in the EXCEL program, the maximum WOB value was determined. To compare the drilling speeds of a traditional rig and a new generation rig, the speed with a 5 ton bit load and a 15 ton bit load is considered, at which, if other things are equal, the ROP increases three times. The drilling speed of wells with an inclined head of the new technology will be 167 m per day versus 105 m with traditional technology, and the operational productivity of drilling with one rig will be 71 m per day versus 51 m. Universal mobile rack rigs with automatic centering of the drill string and mast in vertical and inclined position and gearless hydraulic drive for rotation and movement of the drilling carriage ensure drilling of wells with a horizontal section length of 1500 meters and a diameter of 300 mm.
The opening-up of an opencast system is fundamental in the structure of the mining and technical system (MTS) and the efficiency of the functioning and development of the MTS as a whole depends on the quality of the assessment of its functioning. The decision-making on the reconstruction of the mining and technical system and its subsystems in modern conditions cannot be based only on the basis of a comparison of the technical and economic indicators of the options. Decisions on the development of MTS should be made on the basis of measuring and evaluating the parameters and indicators of the elements of the opening-up of an opencast system and taking into account the requirements of the sustainable development concept, i.e. taking into account the technical, economic, environmental and social aspects of the consequences of decisions taken. However, most of the existing approaches do not allow a comprehensive assessment of all elements of the opening-up of an opencast system, which able to take into account the interrelation between the indicators of the MTS elements in terms of the sustainable development concept. In this paper, we analyzed the factors of the sustainable functioning and development of the MTS and the opening-up of an opencast system, the parameters and indicators for their assessment, as well as the decision-making methods used in the practice of operating the MTS subsystems. The system of parameters and indicators for evaluating the opening-up of an opencast system has been substantiated, taking into account five groups of factors for the functioning of MTS: technical, technological, economic, social and environmental. The use of the fuzzy AHP method for ranking the parameters and indicators of the opening-up of an opencast system is proposed. The methodology and calculation example of assessment of the sustainable development of the opening-up of an opencast system using the fuzzy AHP method are presented. The results of the ranking of the parameters and indicators of the openingup of an opencast system showed that the most significant parameters are economic efficiency, the productivity of the transport complex, social efficiency and environmental efficiency, and the indicators are total income, emissions of pollutants and working conditions of personnel. Using the approach proposed in the work to assess the opening-up of an opencast system will improve: the quality of the assessment of the elements of the opening-up of an opencast system for compliance with the requirements of the sustainable development concept; the effectiveness of decision-making on the design, operational and strategic planning of the MTS development, taking into account the coordination of economic goals with goals in the field of ecology and social development.
During the operation of the mine suspension monorail track and traction device form a mechanical system experiencing high dynamic loads associated with implementation of traction and braking forces. Emerging dynamic loads lead to formation of elastic deformations and oscillations that cause vibrations, which leads to displacement of drive wheels and reduces the implementation of traction. The study of the dynamics of traction device is an important step in improving safety and reliability of monorail transport. The aim of the work is to study dynamics of a friction-type traction device moving along a suspended monorail to assess influence of parameters of the elements of device on the vibrations and nature of interaction of drive wheels with monorail. Research methods. Mathematical modeling of the oscillatory processes resulting from interaction of the running gear of the traction device with the monorail is used. Stages of research include drawing up a design diagram oscillations of drive wheels of the traction device interacting with the monorail, developing a mathematical model for the analysis of vibrations caused by moving loads, also assessing the influence of structural parameters of mechanical system under consideration on nature of oscillations. Research results. The developed mathematical model of friction-type traction device movement allows us to establish relationship between parameters of structural elements of its running gear and pressure mechanism, as well as nature of vibrations that arise. As a result, frequencies of the mechanical system under consideration and maximum deviations were found, which allows you to set optimal device parameters to increase traction and increase lifespan of monorail suspended roads. Findings. It was determined that the frequency range of vibration of drive wheels mainly corresponds to the mid-frequency local vibrations of 16–36 Hz. Increasing length of lever for fixing axles of wheels and reducing their radius leads to formation of low-frequency vibrations with a frequency of less than 15 Hz. When length of lever of drive wheels is more than 0.5 m, shoulder of the spring is more than 0.6 m and radius of drive wheels is less than 0.25 m, vibrations with frequencies below 5 Hz can occur. It was found that increasing the length of lever for securing spring increases the oscillation frequency of one drive wheel and reduces frequency of the other. The difference between
these frequencies significantly affects changes in the pressure of the wheels against monorail. When difference between frequencies is more than 10–12 Hz, direction of load changes pulsed, with a maximum swing of 0.02 rad, which reduces formation of fatigue fractures of tire wheels, and moments of decrease and increase in pressing force have a negative effect on traction, leading to slippage of drive wheels. When difference between frequencies is less than 10–12 Hz, direction of the load changes sharply, with a maximum swing of 0.03 rad, which increases deformation and formation of fatigue fractures of tire wheels, and short moments of weakening and increase of pressing force, constituting 0.1–0.3 s does not have a significant negative effect on traction.
One of the most important indicators characterizing the operating conditions of the fields is the water cut. It negatively affects the way of mining and the possibility of effective use of modern mining technologies. The high water cut of the cover and ore-hosting rocks often serves as the main reason for a decrease in their stability and the manifestation of negative processes (quicksand properties of rocks, caving), as a result of which the safety of miners deteriorates and high-performance mining methods become inapplicable, which generally leads to a decrease in the technical and economic indicators of the open pit. Thus, the study of the regularities of the formation of water inflows in the “Severny” open pit, based on the use of factual material and the development of a sound forecasting methodology are relevant. Purpose of the study. Analyze and assess the mininggeological and mining-technical conditions of the open pit “Severny” using mathematical models. Research methodology. The work uses a modeling method to predict water inflow and calculate the drainage of a quarry field in difficult mining conditions. Devices simulating natural mining conditions were used: a device for electrohydrodynamic analogies (EGDA). Research results: An analogy has been drawn between the phenomenon of laminar steady-state filtration of water in rocks and the passage of current in an electrically conductive medium in the form of electrically conductive paper, less often in liquid electrolytes. The EGDA device was used to determine the water inflows into the quarry, taking into account the factors that complicate the calculations of groundwater filtration (for example, taking into account the movement of the walls of the quarry, the operation of drainage devices, the infiltration of atmospheric precipitation, the movement of water in neighboring aquifers of different permeability), modeling of objects with a complex configuration boundary contours. Conclusion. The modeling method has been improved, which makes it possible to substantiate the use of a specific mining method under certain hydrogeological conditions and to select the optimal drainage scheme to increase the operational reliability of the open pit. The conducted research, observation, study of the existing dam showed the technical feasibility of further development of the deposit with minimization of financial costs. In order to ensure the safety of mining operations, it is envisaged to conduct constant and systemic mining and technical monitoring of mining operations and study the state of the water protection dam and pit walls.
The open method of solid minerals winning occupies a significant place in the total opening of the mining complex deposits of the Republic of Kazakhstan. In the energy band, a prominent role belongs to the Ekibastuz coal basin, where a number of large coal strip mine operates. The level of subsurface, equal parts of spoil bank of the external and internal stripping after a while lead to complex problems of ensuring the stability and safety of mining operations. The location of large external rock dumps on the bead surface has a negative effect on the stability of the latter. The purpose of the work was to establish the degree of the external rock dump influence located on the bead surface on the stability of adjacent rock mass of the coalmine depending on the distance of the dump to the upper edge of the side. There was numerical simulation of stress-strain state of adjacent rock mass under action of distributed load from rock dump carried out. It has been shown that studies of any point stability of the array from this type of load should be carried out on the basis of elasticity and the use of the finite element method theory implemented in packages of programs oriented specifically to scientific and engineering applications. There are the methodology and results of numerical modeling of quantitative assessments of various sections stability of the side loaded with an external rock dump with a height of 160m presented on the example of «Ekibastuz» coal mine. Based on a certain theory of rock strength and the criteria for their discontinuity, limit estimates of the critical distance of the external rock dump from the upper edge of the side were obtained, at which the latter may lose stability.
The aim of the study is to optimize technological solutions to reduce the cost of building a filling array, which remains one of the most pressing issues in the development of ore deposits by underground method. To achieve this goal, a comprehensive research method is used, which includes, first of all, a generalization and analysis of the practice of backfilling of enterprises, geotechnological design in relation to the storey-chamber development system and a feasibility study of optimization solutions at the level of expert assessment using the capabilities of engineering forecasting. Laying works with underground technology of mining of mineral deposits are the most costly, in connection with which research is carried out in order to develop ways to reduce the cost of repayment of the worked-out area. Through a systematic review and critical analysis of existing backfill technologies, the technical feasibility and economic feasibility of combining a hardening mixture and waste rock within a single repayable object has been identified, which provides a radical reduction in the proportion of hardening backfill. In the article offered to the reader’s attention, a variant of the combined array design and the technology of its formation are proposed. A variant of mechanization of the process of erection of the combined massif using specialized dump trucks is provided. This method of forming a combined filling mass allows reducing the volume of the hardening mixture in the total volume of the worked out space of the chambers by not a third. In connection with the complex mechanism of the formation of the combined filling massif, the work considers various options for the discharge of rock into the goaf, which differ in the number of points of discharge of the ingredients of filling materials into the goaf. Based on geotechnological design and mathematical modeling of the formation of a filling massif, it is certain that to increase the efficiency of filling the worked-out chamber space, two points of controlled rock discharge are necessary. The study identified ways to reduce the cost of controlling rock pressure in specific conditions by combining hardening mixture and waste rock for filling voids with a reduction in the proportion of hardening filling up to 50%. A variant of the combined massif construction with mechanization of the massif erection process using specialized dump trucks can significantly reduce the volume of the hardening mixture.
The purpose work. Substantiation and selection of a safe and effective option of mining technology of the experimental block in the pilot industrial mining of the Skalistoe deposit. Method of research. Analysis and synthesis of project solutions, experience in mining inclined low-thickness ore bodies, economic and mathematical modeling and optimization of the parameters of options mining systems in the conditions of the experimental block. Results of research. As a result of research it was established: - the sublevel caving mining system with the parameters adopted in the project does not guarantee the completeness of the extraction of reserves and the effectiveness of mining operations. Project indicators of extraction by sublevel caving technology with frontal ore drawing are overestimated and difficult to achieve in these geological and technical conditions (combination of low thickness and angle of ore body); project scheme for the delivery and transportation of rock mass seems impractical due to the significant volume of heading workings and increased transportation costs; - eight technically rational options of various mining systems were constructed, most relevant to the geological and technical conditions of the deposit. Five variants of the sublevel chamber system and pillar caving, a project variant of sublevel caving technology with frontal ore drawing and two options flat-back cut-and-fill system were considered; - for mining the Skalistoe deposit, according to the results of economic and mathematical modeling, optimal by the criterion of profit per 1 ton of balance reserves of ore is a option of the technology of chamber extraction with dual chambers, frontal drawing of ore by remote-controlled load-haul-dump machine and subsequent pillars caving, as having the greatest profit; - the calculations justified stable spans of dual chambers (25.3 m) and the width of panel pillars (3 m). With an allowable span of 25.3 m, the roof of the dual chambers will be stable with a safety factor of 1.41, and a panel pillar with a width of 3 m has a sufficient margin of safety (more than 1.6) in the whole range of ore body thickness variation; - the proposed scheme of delivery and transportation of rock mass, which allows to reduce the volume of tunnel works by 26% and the average length of transportation by 10-15% compared with the project. Findings. Developed in the process of modernization the technology sublevel chamber system with double-chamber, compared with the project technology, it is possible to significantly increase the efficiency of mining of the low thickness deposit of rich ores Skalistoe by reducing the specific volume of preparatory-rifled work by 34%, the cost of mined ore by 12%, losses and ore dilution – by 2 and 2.9 times, respectively.
ISSN 1998-4502 (Print) ISSN 2499-975Х (Online)