scholarly journals Mechanism and Prevention and Control of Mine Earthquake in Thick and Hard Rock Strata considering the Horizontal Stress Evolution of Stope

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Ming Zhang ◽  
Xuelong Hu ◽  
Hongtao Huang ◽  
Guangyao Chen ◽  
Shan Gao ◽  
...  
Keyword(s):  
Hard Rock ◽  
Design Method ◽  
Horizontal Stress ◽  
Prevention Measures ◽  
Stress Concentrations ◽  
Estimation Model ◽  
Working Face ◽  
Mining Design ◽  
And Control ◽  
Rock Strata

This study investigated the mechanism, prevention measures, and control methods for earthquake disasters typically occurring in mines with thick and hard rock strata. A mine stope with large faults and thick hard rock strata in Hebei Province was taken as the background study object. Then, theoretical analysis and numerical simulation methods were adopted in conjunction with field monitoring to explore how horizontal stress evolves in the thick and hard hanging roofs of such mines, potentially leading to mining earthquakes. Then, based on the obtained results, a mining design method was proposed to reduce the horizontal stress levels of earthquake mitigation. The results showed that, under the control of large faults, semiopen and semiclosed stopes with thick hard rock strata are formed, which cause influentially pressurized and depressurized zones during the evolution of the overburden movements and horizontal stress. It was determined that the stress concentrations mainly originated from the release and transfer of horizontal stress during the rock fractures and movements in the roof areas, which were calculated using a theoretical estimation model. The horizontal stress concentrations formed “counter torques” at both ends of the thick and hard strata, which prevented the support ending due to tensile failures. As a result, the limit spans were increased. This study proposed a mining strategy of using narrow working faces, strip mining processes, and reasonable mining speeds, which could effectively reduce horizontal stress concentrations and consequently prevent and control mining earthquakes. This study’s research results were successfully applied to the mining practices in working face 16103.

Prevention Logic of Rock Burst for Brittle Rock under High Geo-Stress

2011 ◽  
Vol 261-263 ◽  
pp. 1484-1488
Author(s):  
Guo Qing Chen ◽  
Guo Shao Su ◽  
Tian Bin Li
Keyword(s):  
Rock Burst ◽  
Prevention And Control ◽  
Hard Rock ◽  
Deep Tunnel ◽  
Working Face ◽  
Numerical Software ◽  
Released Energy ◽  
Ground Stress ◽  
And Control ◽  
Good Agreement

Rock burst hazard is the main problem of hard rock deep tunnel under high ground stress conditions. The prevention logic of prevention and control of rock burst is proposed by combining local energy release rate index based on the brittle Hoek-Brown model. Stress releasing holes are adopted to lead some energy to release actively and eliminate burst potential of rock burst. Supporting opportunity and parameters were studied by contrasting the magnitude of released energy in FLAC3D numerical software, and then the prevention logic of rock burst is presented. Stress releasing holes relieve stress concentration of the working face, transfer the stress to the deep and reduce the risk of rock burst near the working face. At last, the prevention and control of rock burst for sinping II Hydropower tunnel was analyzed, the results are in good agreement with the actual situations. The proposed method could benefit other deep tunnel projects which have brittle failure.

Calculation and Application of Mining Stress on the Coal Floor

2012 ◽  
Vol 256-259 ◽  
pp. 543-546
Author(s):  
Zhao Ning Gao
Keyword(s):  
Water Inrush ◽  
Horizontal Stress ◽  
Calculation Model ◽  
Vertical Stress ◽  
Distribution Law ◽  
Upward Migration ◽  
Floor Rock ◽  
Working Face ◽  
Original Rock ◽  
Rock Strata

According to the distribution law of the abutment pressure before and behind the working face, the calculation model of the coal floor stress was established and the distribution law of the floor stress along with the advance of face was analyzed. The results show that, in working face ahead, the vertical stress and horizontal stress have generally increased, and the vertical stress is more than horizontal stress, and floor rock strata is in compression bending state with mining influence. Then in the rear of working face, the vertical stress and horizontal stress have generally reduced to less than the original rock stress, and horizontal stress is more than vertical stress. Thus rock bottom is in reverse curving condition, and upward migration of the strata causes the floor drum. Such results can provide theoretical basis for water inrush with pressure mining and treatment of the floor drum of the working face.

scholarly journals Research Progress of Desertification and Its Prevention in Mongolia

2021 ◽  
Vol 13 (12) ◽  
pp. 6861
Author(s):  
Xiya Liang ◽  
Pengfei Li ◽  
Juanle Wang ◽  
Faith Ka Shun Chan ◽  
Chuluun Togtokh ◽  
...  
Keyword(s):  
Model Development ◽  
Mitigation Strategies ◽  
Research Progress ◽  
Prevention Measures ◽  
Interdisciplinary Approaches ◽  
The World ◽  
Impacting Factors ◽  
Decoupling Analysis ◽  
And Control ◽  
The Relationship

Mongolia is a globally crucial region that has been suffering from land desertification. However, current understanding on Mongolia’s desertification is limited, constraining the desertification control and sustainable development in Mongolia and even other parts of the world. This paper studied spatiotemporal patterns, driving factors, mitigation strategies, and research methods of desertification in Mongolia through an extensive review of literature. Results showed that: (i) remote sensing monitoring of desertification in Mongolia has been subject to a relatively low spatial resolution and considerable time delay, and thus high-resolution and timely data are needed to perform a more precise and timely study; (ii) the contribution of desertification impacting factors has not been quantitatively assessed, and a decoupling analysis is desirable to quantify the contribution of factors in different regions of Mongolia; (iii) existing desertification prevention measures should be strengthened in the future. In particular, the relationship between grassland changes and husbandry development needs to be considered during the development of desertification prevention measures; (iv) the multi-method study (particularly interdisciplinary approaches) and desertification model development should be enhanced to facilitate an in-depth desertification research in Mongolia. This study provides a useful reference for desertification research and control in Mongolia and other regions of the world.

scholarly journals Method for designing multi-input system identification signals using a compact time-frequency representation

2021 ◽  
Author(s):  
Mathias Stefan Roeser ◽  
Nicolas Fezans
Keyword(s):  
System Identification ◽  
Design Method ◽  
Flight Test ◽  
Compact Representation ◽  
Time Frequency ◽  
Stability And Control ◽  
Frequency Representation ◽  
Aerodynamic Parameters ◽  
Definition Of ◽  
And Control

AbstractA flight test campaign for system identification is a costly and time-consuming task. Models derived from wind tunnel experiments and CFD calculations must be validated and/or updated with flight data to match the real aircraft stability and control characteristics. Classical maneuvers for system identification are mostly one-surface-at-a-time inputs and need to be performed several times at each flight condition. Various methods for defining very rich multi-axis maneuvers, for instance based on multisine/sum of sines signals, already exist. A new design method based on the wavelet transform allowing the definition of multi-axis inputs in the time-frequency domain has been developed. The compact representation chosen allows the user to define fairly complex maneuvers with very few parameters. This method is demonstrated using simulated flight test data from a high-quality Airbus A320 dynamic model. System identification is then performed with this data, and the results show that aerodynamic parameters can still be accurately estimated from these fairly simple multi-axis maneuvers.

scholarly journals The Impact of COVID-19 on Pedestrian Flow Patterns in Urban POIs—An Example from Beijing

2021 ◽  
Vol 10 (7) ◽  
pp. 479
Author(s):  
Yihang Li ◽  
Liyan Xu
Keyword(s):  
Prevention And Control ◽  
Control Period ◽  
Flow Patterns ◽  
Control Measures ◽  
Pedestrian Flow ◽  
Prevention Measures ◽  
Government Control ◽  
Functional Categories ◽  
And Control ◽  
The Impact

The COVID-19 pandemic is a major challenge for society as a whole, and analyzing the impact of the spread of the epidemic and government control measures on the travel patterns of urban residents can provide powerful help for city managers to designate top-level epidemic prevention policies and specific epidemic prevention measures. This study investigates whether it is more appropriate to use groups of POIs with similar pedestrian flow patterns as the unit of study rather than functional categories of POIs. In this study, we analyzed the hour-by-hour pedestrian flow data of key locations in Beijing before, during, and after the strict epidemic prevention and control period, and we found that the pedestrian flow patterns differed greatly in different periods by using a composite clustering index; we interpreted the clustering results from two perspectives: groups of pedestrian flow patterns and functional categories. The results show that depending on the specific stage of epidemic prevention and control, the number of unique pedestrian flow patterns decreased from four before the epidemic to two during the strict control stage and then increased to six during the initial resumption of work. The restrictions on movement are correlated with most of the visitations, and the release of restrictions led to an increase in the variety of unique pedestrian flow patterns compared to that in the pre-restriction period, even though the overall number of visitations decreased, indicating that social restrictions led to differences in the flow patterns of POIs and increased social distance.

Implementation of Wide-Area and Interconnected FPGA of Embedded Devices

2014 ◽  
Vol 687-691 ◽  
pp. 3102-3105
Author(s):  
Qin Zhang
Keyword(s):  
Design Method ◽  
Functional Module ◽  
Logic Device ◽  
Industrial Control ◽  
Embedded Internet ◽  
Programmable Device ◽  
The Difference ◽  
Development Tendency ◽  
And Control ◽  
Measurement And Control

Integration with Internet is the development tendency of industrial control network, and embedded Internet technique is the key of implementation. By analyzing field bus Technology and combining actual demand, the paper proposes dial-up high-density programmable logic device solution of remote embedded measurement and control equipment. For the purpose of implementing reuse of design modules and upgrading requirement, the paper systematically expounds top-down hierarchy design method for implementing functional module division. According to the difference of implementation complexity because of the difference of functions, the paper finally analyzes the characteristics and applications of programmable device, and proposes the improvement direction.

Multi Mode Vibration Control and Broder Band Motion Control of Three Dimensional Shaking Table

2005 ◽  
Author(s):  
Tsunehiro Wakasugi ◽  
Toru Watanabe ◽  
Kazuto Seto
Keyword(s):  
Vibration Control ◽  
Controller Design ◽  
Design Method ◽  
Three Dimensional ◽  
Design Procedure ◽  
Equation System ◽  
State Equation ◽  
Shaking Table ◽  
Mode Vibration ◽  
And Control

This paper deals with a new system design method for motion and vibration control of a three-dimensional flexible shaking table. An integrated modeling and controller design procedure for flexible shaking table system is presented. An experimental three-dimensional shaking table is built. “Reduced-Order Physical Model” procedure is adopted. A state equation system model is composed and a feedback controller is designed by applying LQI control law to achieve simultaneous motion and vibration control. Adding a feedforward, two-degree-of-freedom control system is designed. Computer simulations and control experiments are carried out and the effectiveness of the presented procedure is investigated. The robustness of the system is also investigated.

Design of Mine Ventilation Systems Based on Artificial Intelligence

2014 ◽  
Vol 614 ◽  
pp. 107-112
Author(s):  
Xiao Yu Yin ◽  
Xian Ping Xie ◽  
Zhen Li ◽  
Jian Gong Li ◽  
Ting Jun Wang ◽  
...  
Keyword(s):  
Expert System ◽  
Computer Aided Design ◽  
Design Method ◽  
Mine Ventilation ◽  
Design System ◽  
Knowledge Based ◽  
Aided Design ◽  
And Control ◽  
Intelligent Computer ◽  
Ventilation Systems

Expert systems, or knowledge based systems, are programs in which the answer to a user-posed question is reached by logical or plausible inference rather than strictly by calculation, although calculation routines can form a major part of an expert system. Based on the integration of expert system technology and optimization technology, an intelligent computer aided design method for mine ventilation systems is proposed in this paper. Firstly, the structure and control algorithm of the intelligent design system are explored. Secondly, the knowledge types required for the mine ventilation expert system and the acquiring method of knowledge are discussed. Finally, the inference method of this expert system is put forward.

scholarly journals The Impact of the Direct Participation of Workers on the Rates of Absenteeism in the Spanish Labor Environment

2020 ◽  
Vol 17 (7) ◽  
pp. 2477 ◽  
Author(s):  
Raúl Payá Castiblanque
Keyword(s):  
Multinomial Logistic Regression ◽  
Management Plan ◽  
Risk Prevention ◽  
Prevention Measures ◽  
Direct Participation ◽  
High Level ◽  
And Control ◽  
The Impact ◽  
The Relationship ◽  
Transversal Study

The aim of this research was to study the relationship between the different levels of direct participation of workers (passive, consultative or active-delegated) in risk prevention management with the levels of absenteeism in Spain. To this end, a transversal study was carried out using microdata from the Second European Survey of Companies on New and Emerging Risks (ESENER-2-Spain, 2014) with a master population of 3162 work centres. A multinomial logistic regression model was carried out, with the dependent variable being the levels of absenteeism and the independent variables, the participation indicators and preventive management, calculating the adjusted odds ratio (aOR) between all the independent and control variables, with their corresponding 95% confidence intervals (95% IC). The results obtained showed how the active-delegative participation of workers in the design and adoption of psychosocial risk prevention measures reported 2.33 less probabilities of having a very high or fairly high level of absenteeism (aOR = 0.43; 95%IC:0.27–0.69). However, having documented aspects of preventive management (plan, risk assessment, planning measures) did not have any impact on absenteeism levels, which shows that we can fall into an unrealistic institutional mirage of security with active policies of co-education or co-management being necessary to reduce absenteeism.

Sign in / Sign up

Export Citation Format

Share Document