scholarly journals An Innovative Method for Placement of Gangue Backfilling Material in Steep Underground Coal Mines

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 107 ◽  
Author(s):  
Yanchun Yin ◽  
Tongbin Zhao ◽  
Yubao Zhang ◽  
Yunliang Tan ◽  
Yue Qiu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Large Scale ◽  
Small Scale ◽  
Underground Coal Mining ◽  
Long Distance ◽  
Subsidence Area ◽  
Working Face ◽  
Underground Coal Mines ◽  
Gob Area ◽  
Gangue Backfilling

Using gangue backfilling in underground coal mining not only controls the roof deformation in the gob area but also reduces the amount of mining waste rock. However, due to the limitations of the complicated engineering conditions, backfilling mining in the steep coal seam is not widely applied. In this study, a long-distance backfilling technology with a scraper winch for a steep coal seam was proposed and applied in a flexible shield supporting working face in Datai Mine, Beijing. Aiming at the problem of the decreasing backfilling ratio in field practice, numerical simulation was carried out to research the moving law of gangue in the goaf. The gangue mainly experienced four stages: gangue landslide stage, small-scale subsidence stage, funnel-shaped subsidence stage, and large-scale subsidence stage. The moving area of the gangue could be divided into five areas including a motionless area, a landslide area, a subsidence area, a funnel-shaped subsidence area, and a to-be-backfilled area. With the increase of the inclined length of the working face, the moving time of the gangue increased gradually. Based on the simulation results, the scheme of backfilling and mining in Datai Mine was optimized, for which the inclined length of the working face was shortened, and a higher backfilling ratio was obtained.

scholarly journals Failure Mechanism of Rock Bridge Based on Acoustic Emission Technique

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Guoqing Chen ◽  
Yan Zhang ◽  
Runqiu Huang ◽  
Fan Guo ◽  
Guofeng Zhang
Keyword(s):  
Acoustic Emission ◽  
Failure Mechanism ◽  
High Speed ◽  
Large Scale ◽  
Small Scale ◽  
Failure Behavior ◽  
Long Distance ◽  
Rock Bridge ◽  
Rocky Slope ◽  
Landslide Model

Acoustic emission (AE) technique is widely used in various fields as a reliable nondestructive examination technology. Two experimental tests were carried out in a rock mechanics laboratory, which include (1) small scale direct shear tests of rock bridge with different lengths and (2) large scale landslide model with locked section. The relationship of AE event count and record time was analyzed during the tests. The AE source location technology and comparative analysis with its actual failure model were done. It can be found that whether it is small scale test or large scale landslide model test, AE technique accurately located the AE source point, which reflected the failure generation and expansion of internal cracks in rock samples. Large scale landslide model with locked section test showed that rock bridge in rocky slope has typical brittle failure behavior. The two tests based on AE technique well revealed the rock failure mechanism in rocky slope and clarified the cause of high speed and long distance sliding of rocky slope.

Dynamics of a Large Scale Hydraulic Capsule Pipeline System

1999 ◽  
Vol 124 (1) ◽  
pp. 191-195 ◽  
Author(s):  
Hongliu Du ◽  
Satish S. Nair
Keyword(s):  
Large Scale ◽  
Control Method ◽  
Experimental Studies ◽  
Small Scale ◽  
Pipeline System ◽  
Centrifugal Pumps ◽  
Long Distance ◽  
Column Separation ◽  
In Series ◽  
Hydraulic Capsule Pipeline

The dynamics of a booster station, which is critical for the control of a novel, long distance, hydraulic capsule pipeline, is simulated mathematically for design studies and control of the hydraulic transients caused by the valve actuators in the system. Several modifications to the pump bypass station configuration of the booster station have been studied. With the objective of eliminating column separation and reducing flow reversals, a configuration with several centrifugal pumps connected in series, and a carefully sized air chamber is found to be a viable design. A valve control method is designed to eliminate column separation and the design results in acceptable flow reversal levels in the main pipe. The simulation results match with trends in limited experimental studies performed on a small scale experimental capsule pipeline system.

scholarly journals Fairness Time-Slot Allocation and Scheduling with QoS Guarantees in Multihop WiMAX Mesh Networks

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Chien-Yu Wu ◽  
Hann-Jang Ho ◽  
Sing-Ling Lee ◽  
Liang Lung Chen
Keyword(s):  
Large Scale ◽  
Heuristic Algorithms ◽  
Mesh Networks ◽  
Time Slot ◽  
Optimal Solution ◽  
Small Scale ◽  
Scheduling Problem ◽  
Slot Allocation ◽  
Long Distance ◽  
Time Slot Allocation

The WiMAX technology has been defined to provide high throughput over long distance communications and support the quality of service (QoS) control applied on different applications. This paper studies the fairness time-slot allocation and scheduling problem for enhancing throughput and guaranteeing QoS in multihop WiMAX mesh networks. For allocating time slots to multiple subscribe stations (SSs), fairness is a key concern. The notion of max-min fairness is applied as our metric to define the QoS-based max-min fair scheduling problem for maximizing the minimum satisfaction ratio of each SS. We formulate an integer linear programming (ILP) model to provide an optimal solution on small-scale networks. For large-scale networks, several heuristic algorithms are proposed for better running time and scalability. The performance of heuristic algorithms is compared with previous methods in the literatures. Experimental results show that the proposed algorithms are better in terms of QoS satisfaction ratio and throughput.

Gas Control Technology for Fully Mechanized Face of Outburst Coal Seam with Hard Roof during Initial Caving

2011 ◽  
Vol 347-353 ◽  
pp. 974-978
Author(s):  
Ju Gen Fu ◽  
Wei Wu ◽  
Gen Yong Hua
Keyword(s):  
Coal Seam ◽  
Shock Pressure ◽  
Control Technology ◽  
Large Area ◽  
Hard Roof ◽  
Working Face ◽  
Initial Release ◽  
Gob Area ◽  
Outburst Coal Seam ◽  
Presplit Blasting

In the fully mechanized working face, with working face forward, gob area become bigger and bigger, when the top area reach a certain span ,roof in gob suddenly cave, outspreading a large quantity of mine gas, easy to cause the gas overrun and gas accidents. In addition, shock pressure which is caused when large area roof cave, easily causing casualties and damage of equipment. This paper introduces Pan three Coal mine 17171(1) ore advance of fully mechanized working face presplit blasting, rotating stoping and comprehensive extraction technologies, which successfully solve the roof management and the gas problems during initial release, achieving good security benefits.

scholarly journals Routing Protocol berbasis Cluster Segitiga

2015 ◽  
Vol 4 (2) ◽  
Author(s):  
Nurhayati Nurhayati
Keyword(s):  
Routing Protocol ◽  
Large Scale ◽  
Cluster Head ◽  
Network Routing ◽  
Base Station ◽  
Sensor Nodes ◽  
Wireless Sensor ◽  
Small Scale ◽  
Long Distance ◽  
Scale Network

Wireless sensor networks users are increasing drastically in communication and technology. They consist of small battery powered devices with limited energy resources. Once deployed, the small sensor nodes are usually inaccessible to the user, and thus replacement of the energy source is not feasible. However, the smaller of a device the better it is. The development of device should be user friendly. Hence, energy efficiency is a key design issue that needs to be enhanced in order to improve the life span of the network. In BCDCP, all sensors send data from CH (Cluster Head) and then to BS (Base Station).  BCDCP works well in small-scale network but in large scale network it is not appropriated since it uses much energy for long distance wireless communication. We propose a routing protocol  -  Triangular Clustering  Routing Protocol  (TCRP)  -  to prolong network life time through the balanced energy consumption.  RPTC selects cluster head of triangular shape. The sensor field is divided into energy level and in every level we choose one node as a gate node. This gate node collects data and sends it to the leader node. Finally the leader node sends the aggregated data to the BS. We show TCRP outperforms BCDCP with several experiments. Key words: Wireless Sensor Network, Routing Protocol, Clustering

scholarly journals Settlement Oscillations in the Negev Highlands Revisited: The Impact of Microarchaeological Methods

Radiocarbon ◽  
2015 ◽  
Vol 57 (2) ◽  
pp. 253-264 ◽  
Author(s):  
Ruth Shahack-Gross ◽  
Israel Finkelstein
Keyword(s):  
Iron Age ◽  
Large Scale ◽  
Water Diversion ◽  
Small Scale ◽  
Long Distance ◽  
Islamic Period ◽  
Ceramic Petrography ◽  
Early Islamic Period ◽  
The Impact ◽  
Early Islamic

Microarchaeological methods, especially those focused on geoarchaeology and radiocarbon dating, have revolutionized the manner in which the Iron Age settlement peak in the Negev Highlands is interpreted. We review here results from field and laboratory studies conducted at two Iron Age sites (Atar Haroa and Nahal Boqer) compared to one Byzantine/Early Islamic site (Wadi el-Mustayer)—all located near Sede Boqer. We present our methodology, which is based on small-scale but detailed excavations, study of sediments, and identification of livestock dung remains and their utility as indicators of past subsistence practices. To this we add meticulous 14C dating, ceramic petrography, and identification of botanic and zoological remains. We conclude that subsistence during the Iron Age included tending livestock but did not include agriculture. We further propose that the long-distance trade of copper from the Arabah Valley under Egyptian auspices and possibly the trading of cinnamon, dates, and other Arabian/Indian commodities were the driving force in the initiation (and later decline) of the Iron Age settlement system. We hypothesize that the agricultural settlement peak during the Byzantine/Early Islamic period was also influenced by an imperial power from outside of the Negev and that large-scale agriculture was enabled due to the adoption of new agricultural techniques, including terracing of ephemeral streams along with water diversion systems and possibly water storage facilities such as advanced cisterns. Future studies are expected to shed additional light on the complexity of settlement oscillations in the Negev Highlands region in key periods such as the Early and Intermediate Bronze Ages.

Numerical Simulation and Study of the Effect between "Three-Zone" Distribution in Goaf and Air Volume in Working Face

2014 ◽  
Vol 962-965 ◽  
pp. 1158-1164
Author(s):  
Yan Zhao ◽  
Yan Chuan Li
Keyword(s):  
Numerical Simulation ◽  
Oxygen Concentration ◽  
Large Scale ◽  
Oxidation Zone ◽  
Small Scale ◽  
Air Leakage ◽  
Exponential Relationship ◽  
Air Volume ◽  
Working Face ◽  
Result Show

We conducted a numerical simulation of oxygen concentration in goaf using Comsol4.3b when the air volume in working face ranges from 500 m3/min to 900m3/min. The result show that with the air volume increasing the oxygen concentration boundary of 18% move to deep goaf in a small scale, while the boundary of 8% move to deep goaf in a large scale and show an exponential relationship, in other words air volume change greatly affect the 8% boundary. The boundary of maximum air leakage and air leakage 0.004% all display an exponential relationship with air volume. But the movement scale of air leakage boundary 0.004% is small. The width of oxidation zone increases obviously with air volume increasing and the relations formula is Lmax= 100.4ln (Q)-25.55ln (Q)-410.4. Draw a conclusion that in ventilation management air volume should be reduced appropriately in order to reduce the width of oxidation zone and slow the speed of moving to deep goaf, thus control spontaneous combustion in goaf.

Small-Scale Science to Large-Scale Profession

2000 ◽  
Vol 45 (4) ◽  
pp. 396-398
Author(s):  
Roger Smith
Keyword(s):  
Large Scale ◽  
Small Scale

Development of Physics Learning Module Based on Guided Inquiry with Light Wave Material in Class XI of Senior High School

2020 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Evi Rahmawati ◽  
Irnin Agustina Dwi Astuti ◽  
N Nurhayati
Keyword(s):  
Large Scale ◽  
Learning Strategy ◽  
Student Response ◽  
Average Score ◽  
Small Scale ◽  
Design Development ◽  
Teacher Response ◽  
Student Responses ◽  
Analysis Design ◽  
Scientific Skills

IPA Integrated is a place for students to study themselves and the surrounding environment applied in daily life. Integrated IPA Learning provides a direct experience to students through the use and development of scientific skills and attitudes. The importance of integrated IPA requires to pack learning well, integrated IPA integration with the preparation of modules combined with learning strategy can maximize the learning process in school. In SMP 209 Jakarta, the value of the integrated IPA is obtained from 34 students there are 10 students completed and 24 students are not complete because they get the value below the KKM of 68. This research is a development study with the development model of ADDIE (Analysis, Design, Development, Implementation, and Evaluation). The use of KPS-based integrated IPA modules (Science Process sSkills) on the theme of rainbow phenomenon obtained by media expert validation results with an average score of 84.38%, average material expert 82.18%, average linguist 75.37%. So the average of all aspects obtained by 80.55% is worth using and tested to students. The results of the teacher response obtained 88.69% value with excellent criteria. Student responses on a small scale acquired an average score of 85.19% with highly agreed criteria and on the large-scale student response gained a yield of 86.44% with very agreed criteria. So the module can be concluded receiving a good response by the teacher and students.

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