scholarly journals Dynamics control of powered hydraulic roof supports in the underground longwall mining complex

2021 ◽  
Vol 942 (1) ◽  
pp. 012014
Author(s):  
P Rudzki ◽  
P Krot
Keyword(s):  
Longwall Mining ◽  
Underground Mining ◽  
Outer Space ◽  
Fast Reaction ◽  
Hydraulic Unit ◽  
New Approach ◽  
Helical Springs ◽  
Control Functions ◽  
Hydraulic Cylinders ◽  
Shock Impacts

Abstract The study presents the dynamic analysis of the hydraulic cylinders operated in the powered roof support sections as an important part of the longwall underground mining complexes. This type of hydraulic unit is subjected to frequent shock impacts from the significant rock masses released on the top of mined caverns. Hydraulic props are equipped with safety valves with steel helical springs, which intend to reduce peak loads by the relief of internal pressure. These valves respond to shock with a time delay due to the limited velocity of the pressure wave inside the cylinder and an additional pipe of a small section, which restricts fluid flow in outer space. The new approach represented in this paper is based on mathematical modelling of the interaction of the hydraulic and mechanical parts and using additional signals to control safety valves. Detection of shock in advance (0.02-0.05 s) allows reducing pressure peaks by 30% and avoid failures. The challenges are the development of a “smart valve” with optimised control functions by the signals from additional sensors (vibration, deformation, piston position) and providing fast reaction time with a high flow rate under pressures up to 100 MPa.

scholarly journals Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 3016 ◽  
Author(s):  
Shen ◽  
Wang ◽  
Cao ◽  
Su ◽  
Nan ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Longwall Mining ◽  
Underground Mining ◽  
Failure Criteria ◽  
Normal Operation ◽  
Analysis Model ◽  
Plane Stress Condition ◽  
Field Case ◽  
Hard Roof ◽  
Soft Interlayer

Due to the additional abutment stress, interactional hard roof structures (IHRS) affect the normal operation of the coal production system in underground mining. The movement of IHRS may result in security problems, such as the failure of supporting body, large deformation, and even roof caving for nearby openings. According to the physical configuration and loading conditions of IHRS in a simple two-dimensional physical model under the plane stress condition, mining-induced failure criteria were proposed and validated by the mechanical behavior of IHRS in a mechanical analysis model. The results indicate that IHRS, consisting of three interactional parts—the lower key structure, the middle soft interlayer, and the upper key structure—are governed by the additional abutment stress induced by the longwall mining working face. The fracture of the upper key structure in IHRS can be explained as follows: Due to the crushing failure, lower key structure, and middle soft interlayer yield, the action force between the upper and lower key structures vanishes, resulting in fracture of the upper key structure in IHRS. In a field case, when additional abutment stress reaches 7.37 MPa, the energy of 2.35 × 105 J is generated by the fracture of the upper key structure in IHRS. Under the same geological and engineering conditions, the energy generated by IHRS is much larger than that generated by a single hard roof. The mining-induced failure criteria are successfully applied in a field case. The in-situ mechanical behavior of the openings nearby IHRS under the mining abutment stress can be clearly explained by the proposed criteria.

Access to space: A new approach by the united nations office for outer space affairs

2018 ◽  
Vol 152 ◽  
pp. 201-207 ◽  
Author(s):  
Ayami Kojima ◽  
Daniel García Yárnoz ◽  
Simonetta Di Pippo
Keyword(s):  
United Nations ◽  
Outer Space ◽  
New Approach ◽  
The United Nations

scholarly journals Surface Subsidence Prognosis above an Underground Longwall Excavation and Based on 3D Point Cloud Analysis

Minerals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 82 ◽  
Author(s):  
Andrej Pal ◽  
Janez Rošer ◽  
Milivoj Vulić
Keyword(s):  
Rock Mass ◽  
Longwall Mining ◽  
Underground Mining ◽  
Point Clouds ◽  
Surface Subsidence ◽  
Protection Measures ◽  
Engineering Research ◽  
3D Point Clouds ◽  
Research Activities ◽  
And Control

Impacts of underground mining have been reduced by continuous environmental endeavors, scientific, and engineering research activities, whose main object is the behavior and control of the undermined rock mass and the subsequent surface subsidence. In the presented Velenje case of underground sublevel longwall mining where coal is being exploited both horizontal and vertical, backfilling processes and accompanying fracturing in the coal layer, and rock mass are causing uncontrolled subsidence of the surface above. 3D point clouds of the study were acquired in ten epochs and at excavation heights on the front were measured at the same epochs. By establishing a sectors layout in the observational area, smaller point clouds were obtained, to which planes were fitted and centroids of these planes then calculated. Centroid heights were analyzed with the FNSE model to estimate the time of consolidation and modified according to excavation parameters to determine total subsidence after a certain period. Proposed prognosis approaches for estimating consolidation of active subsidence and long term surface environmental protection measures have been proposed and presented. The C2C analysis of distances between acquired 3D point clouds was used for identification of surface subsidence, reclamation areas and sink holes, and for validation of feasibility and effectiveness of the proposed prognosis.

scholarly journals A Comprehensive Method for Subsidence Prediction on Two-Seam Longwall Mining

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3139 ◽  
Author(s):  
Bin Zhang ◽  
Jiacheng Ye ◽  
Zhongjian Zhang ◽  
Liang Xu ◽  
Nengxiong Xu
Keyword(s):  
Longwall Mining ◽  
Underground Mining ◽  
Surface Subsidence ◽  
Orthogonal Experimental Design ◽  
Parameter Inversion ◽  
Subsidence Prediction ◽  
Reliable Assessment ◽  
Seam Mining ◽  
Subsidence Monitoring ◽  
Overlying Strata

The purpose of mining subsidence prediction is to establish a reliable assessment for surface subsidence resulting from underground mining. In this study, a new method for predicting subsidence in two-seam mining is proposed. First, the surface subsidence due to mining the upper seam is monitored. Then, taking the subsidence data as indicators, the optimal mechanical parameters of overlying strata can be obtained by orthogonal experimental design and inverse analysis of numerical simulation. Finally, further subsidence is calculated and predicted by the numerical model. A case of two-seam underground mining is studied using this methodology. This coal mine is located in the Dongsheng coal field in Inner Mongolia, China. Based on GPS surface subsidence monitoring and parameter inversion, the subsidence induced by two-seam mining is estimated and predicted. This study shows that the ratio of the height of overlying strata to mining thickness (H/M), mining configuration and adjacent mining have a significant effect on the surface subsidence caused by two-seam mining. By parameter inversion, the proposed optimal parameters can be applied to predict the subsidence of a nearby mine with similar stratigraphic conditions. Furthermore, this methodology can also be used to predict the subsidence caused by mining of more than two seams.

scholarly journals Viva Di Bartini: Eleven New Laws of Conservation Expanding Physics for Global Strategic Management and Strategic Development

2020 ◽  
Vol 11 (1) ◽  
pp. 1
Author(s):  
Andrei G. Aleinikov ◽  
David A. Smarsh
Keyword(s):  
Strategic Management ◽  
History Of Science ◽  
Outer Space ◽  
Strategic Development ◽  
New Approach ◽  
New Horizons ◽  
The World ◽  
History Of ◽  
Management Issues ◽  
Real World Problems

This article illustrates how 11 new Laws of Conservation (Aleinikov, 2004, 2005, 2007a,b,c,d,e; Aleinikov & Smarsh, 2007, 2009a, 2009b, 2011; Aleinikov & McFarland, 2008a, 2008b, 2009) expand the Bartini/Kuznetsov LT system of interpretation of laws of physics (Bartini, 1965, 1966, 2005; Kuznetsov & Bolshakov, 2000), thus expanding the physics and strategic management horizons. The new laws are described, explained, and, in some cases, shown in their application to real world problems, including outer space research and global strategic management issues. However, the main contribution of these discoveries is certainly the opening of new horizons for scientific research – the global strategic development of science. In the history of science, these new laws represent an opportunity for a heuristic leap. While in old times, it took about 50-100 years to discover one new law of conservation, the new approach offered by Robert Oros di Bartini and implemented by our research group, allowed us to discover 11 new laws of conservation within five years. It means 100 times acceleration! That's why this article is titled “Viva di Bartini!” It emphasizes the contribution of the great engineer and scientist, named a “prescient genius” by press, to the strategic development of science, including the first in the world MANAGEMENT SYSTEM FOR LAWS OF CONSERVATION that led to a revolutionary leap in developing new laws and new sciences, including the science of genius – Geniusology, first mentioned in 2003, published in 2004, as described in (Aleinikov, 2013a).

Estimation of Salt Rocks’ Long-Term Strength in Natural Conditions

2015 ◽  
Vol 243 ◽  
pp. 11-16
Author(s):  
Alexander A. Baryakh ◽  
Sergey Yu. Lobanov ◽  
Ivan S. Lomakin
Keyword(s):  
Underground Mining ◽  
Term Strength ◽  
New Approach ◽  
In Situ Data ◽  
The Earth ◽  
Deformation And Fracture ◽  
Strength Based ◽  
Fracture Processes

New approach to construction curve of salt rock’s long-term strength based on the diagram’s analysis of the earth surface subsidence growth under the influence of underground mining has been proposed. Performed verification of received estimation showed acceptable fit of mathematical modeling results of interchamber pillars’ deformation and fracture processes with in-situ data.

Ground surface subsidence as effect of underground mining of the thick coal seams in the Jiu valley basin / Osiadanie gruntów wskutek wybierania pokładów o dużej miąższości w kopalniach zagłębia w dolinie Jiu

2012 ◽  
Vol 57 (3) ◽  
pp. 547-577 ◽  
Author(s):  
Ilie Onica ◽  
Dacian Marian
Keyword(s):  
Surface Deformation ◽  
Longwall Mining ◽  
Underground Mining ◽  
Ground Surface ◽  
Surface Subsidence ◽  
Coal Seams ◽  
Elasto Plasticity ◽  
Ground Surface Subsidence ◽  
Time Dependent Analysis

Abstract In the case of the thick and gentle coal seam no. 3 of the Jiu Valley Coal Basin (Romania), the mining methods are by use of the longwall mining technologies with roof control by caving or top coal caving. In this paper, it is presented the analysis of the complex deformations of the ground surface, over time, as a consequence of the coal mining in certain mining fields of the basin. Also, it is analysed the ground surface subsidence phenomenon using the CESAR-LCPC finite element code. The modelling is made in the elasticity and the elasto-plasticity behaviour hypothesis. Also, the time dependent analysis of the ground surface deformation was achieved with the aid of an especial profile function. The obtained results are compared with the in situ measurements data basis.

Outer space and the idea of the global commons

2021 ◽  
pp. 004711782110362
Author(s):  
Mai’a K. Davis Cross
Keyword(s):  
Participant Observation ◽  
Outer Space ◽  
Past Century ◽  
New Approach ◽  
Global Commons ◽  
Space Race ◽  
Wide Scale ◽  
Societal Level ◽  
Other Regarding

Drawing upon fresh archival research and participant observation, the author traces the emergence and transformative idea of the non-weaponized and peaceful use of space from the 1920s to today. Building on this, the case study questions much of the common wisdom surrounding humans’ relationship with space over the past century. Although the beginnings of the Space Age are usually thought to have closely coincided with the Space Race beginning in 1955, the paper goes further back to the Spaceflight Movement of the 1920s and 30s, tracing the emergence of the idea of space as part of the global commons. This societal-level movement was highly transnational and collaborative in nature, and pushed for the achievement of human spaceflight decades before the technology existed, at the same time advocating for space as a peaceful domain for all of humankind. Using a new approach that also provides the basic ontological assumption for Model 3 of the special issue framework, the author argues that the impetus to engage in space exploration was fundamentally ‘ultrasocial’, defined as a human predisposition to be other-regarding, empathic, and inclined toward seeking wide-scale cooperation, even among strangers.

scholarly journals Integrated Turbine-Compressor Controls Retrofit for an Olefins Unit

1995 ◽  
Author(s):  
John R. Gaston ◽  
W. Brian Piercy ◽  
C. Scott Harclerode
Keyword(s):  
Control System ◽  
Gas Turbines ◽  
System Structure ◽  
New Approach ◽  
Significant Control ◽  
Control Functions ◽  
Gas Compression ◽  
Load Regulation ◽  
Save Energy

The Olefins Unit that is the subject of this case study has been operating for 25 years. Recently, the unit initiated a control system retrofit program to increase availability, save energy, and improve access to operating information. New control systems were installed on the ethylene, propylene and furnace gas compressor trains. The gas compression equipment consists of single and multi-case compressor trains driven by steam and gas turbines and electric motors. Significant control system improvements were made to the turbine/compressor speed/load regulation and temperature limiting. The systems also execute “safety system” logic for process and machinery protection. In addition to integrated turbine compressor control, the strategy that incorporates all control functions for the entire compresor train, a new anti-surge algorithm is included. To meet more stringent availability requirements imposed by integration, a triple modular redundant (TMR) system structure is employed. The surge algorithm described in this paper accurately predicts where surge occurs, regardless of changes in gas composition and conditions (e.g., molecular weight, temperature, etc.), and allows the integrated controls to compensate accordingly. A PC workstation-based operator display is provided for enhanced operator awareness of machinery conditions. This paper describes the requirements and implementation of this new approach to control.

Architectural Lighting Design Concept for the Interior Yard of a Prospective Orbital Station

2021 ◽  
pp. 131-136
Author(s):  
Nikolay L. Pavlov ◽  
Georgy A. Shcheglov
Keyword(s):  
Spatial Structure ◽  
Outer Space ◽  
Space Station ◽  
Three Dimensional ◽  
Orbital Station ◽  
Coordinate Structure ◽  
Control Functions ◽  
Working Space ◽  
Starting Point ◽  
New Generation

A design aspect of a three-dimensional workspace for an upcoming deployment stage of a new-generation manned space station with crews of several dozen people is considered. It is assumed that in the new closed layout of the station, the spatial core is its courtyard, which ensures productive and safe human activity not only in pressurized living and working modules, but also in an airless space. The aim of the work is to develop the concept for architectural illumination of the surface and the entire working space in the courtyard of the new-generation orbital station. The original layout diagram of the orbital station is presented. Its illumination is investigated by the method of computer geometric modelling. The most common orthogonal structures implemented in the MIR and ISS projects were chosen as the starting point for constructing the spatial structure of the orbital station. The illumination system is proposed that implements the operational and control functions of the crew members, as well as their orientation and positioning both in the spatial structure of the station itself and in the surrounding space. To implement these functions, two basic techniques for setting up remotely controlled stationary and mobile luminaires are proposed. The importance of highlighting the central axial structure of the station as a coordinate system for constant orientation is shown when people are located both in the inner space of the station and in the space of its yard. It is concluded that the illumination of the three-axis coordinate structure projected onto the outer space in relation to the station space, will give its perception a feeling of familiar stability.

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