Engineering Commons^™

Equivalent Roughness And Its Application In Calculating Friction Drag Of Mine Roadway, Yan Zhou, Xingshen Wang

U.S. Mine Ventilation Symposium

Some roadways, which do not behave as "wholly rough pipe" as we expected, will have different impact on airflow in a mine ventilation network because of the low Reynolds numbers. For a "non-Wholly-rough" roadway, its resistance factor (R) or the friction factor (¦) is not only dependent upon the relative roughness but also dependent upon the Reynolds number, which varies directly as the flow rate. In this case, R or ¦ is no longer a constant independent of flow rate. Thus, in order to correctly calculate the friction drag of the same roadway for different flow rates, ¦ must be …

Modelling Of The Occurrence Of Hydrogen Sulphide In Coal Seams, A. D. Stewart Gillies, Mehmet S. Kizil, Hsin Wei Wu, Timothy J. M. Harvey

U.S. Mine Ventilation Symposium

Hydrogen Sulphide (H₂S) has been encountered within a number of Bowen Basin collieries, Central Queensland, Australia. High concentration occurrence during mining of a longwall panel raises a number of potential problems, which demand greater understanding to allow efficient mining while maintaining safe and healthy environmental conditions. Longwall panels at Mine A and Mine B have recently mined through H₂S zones. The high H₂S zone mined through at Mine A was wide and covering the whole length of the face comparing to the narrow H₂S zone which was cutting the panel at 45° …

Characteristics Of Airborne Dust In The Return Airways Of The Mechanized Longwall Face, Tevfik Güyagüler, Sinan Keskin

U.S. Mine Ventilation Symposium

In this paper the results of a research study on the characterisation of airborne dust in the return airway of the mechanized longwall face at Middle Anatolian Lignite Mine, OAL are presented. Dust, temperature, moisture and air velocity measurements were carried out in the return airways of the fully mechanized longwalls. Then the analyses of results on real-time concentration data, mass concentration data, effect of moisture, heat and air velocity on dust concentration are made. It has been found that amount of dust in return airway is directly related to the face activities and to the amount of settled dust …

Mitigation Of Methane Emissions From Coal Mine Ventilation Air, Peter Carothers, Milind D. Deo

U.S. Mine Ventilation Symposium

U.S. EPA's coalbed methane outreach program, (CMOP) has prepared a technical assessment of techniques that combust trace amounts of coal mine methane contained in ventilation air. Control of methane emissions from mine ventilation systems has been an elusive goal because of the magnitude of a typical airflow and the very low methane concentrations. One established and cost-effective use feeds the air into a prime mover in lieu of ambient combustion air. This method usually consumes just a fraction of the flow available from each ventilation shaft. The authors evaluated the technical and economic feasibility of two emerging systems that may …

The General Characteristics Of Electromagnetic Radiation During Coal Fracture And Its Application In Outburst Prediction, Xue-Qiu He, En-Yuan Wang, Zhentang Liu

U.S. Mine Ventilation Symposium

Coal and methane outburst are catastrophic in coal mining, their prediction is difficult. In this paper, the electromagnetic radiation (EMR) generated during coal or rock deformation and fracturing is measured and analyzed. The results show that EMR truly exists during the fracture of coal or rock (with or without the presence of gas). It follows the Hurst statistical rule, and it basically exhibits gradually enhancing tendency during the process. The EMR strength and frequency are correlated to the coal or rock fracture process. Based on the experimental and theoretical studies, a new method for coal and methane outburst prediction is …

Scale Tests, In-Situ Measurements And Simulation Of Methane Gas Distribution At Heading Faces, Shinsuke Nakayama, Masamoto Ichinose, Kenichi Uchino, Masahiro Inoue

U.S. Mine Ventilation Symposium

Distributions of methane gas concentration at a heading face with an auxiliary fan were measured in both an actual coal mine and a scale model. As a result, general distribution pattern of methane gas concentration was elucidated and it was found that there exist several areas where gas concentrations tend to rise to dangerous levels. A CFO (Computational Fluid Dynamics) method was also developed and the results of the computation were compared with those obtained in these measurements. It was concluded that the CFD can be used for simulating the distributions of gas concentration that are affected by conditions in …

A New Laboratory Technique To Estimate Gas Diffusion Characteristics Of Coal, Satya Harpalani, Shaofan Ouyang

U.S. Mine Ventilation Symposium

This paper describes a new experimental technique developed to measure the diffusion coefficient (D) for a coal-methane system using the transient flow mechanism, and examine its dependency on factors that change with continued flow – pressure and gas concentration. Although developed primarily for coalbed methane reservoirs and coal in the gob regions, it also has application in situations where a second gas is injected in coal since it utilizes the principle of counter-diffusion. The results show that there is a continuous decrease in the value of D with decreasing mean concentration of methane in coal. The logarithm of D varies …

Gob Well Flaring: Design And Impact Analysis, Daniel J. Brunner, Karl Schultz

U.S. Mine Ventilation Symposium

Currently, over 30 U.S. Coal Mining operations employ a system of degasification to assist in reducing the emission of methane into their mine ventilation systems. All of these mines use vertical gob wells. This is an effective gob de gasification technique for U.S. longwall coal mining operations, particularly when prime movers apply suction to the wellheads (active gas extraction). In most cases mine operators discharge gas recovered from gob wells directly to the atmosphere. This practice poses safety and environmental concerns, and wastes a potential resource. In the U.S. there are no standards for equipping actively extracted or passive gob …

Economic Analysis Of Coalbed Methane Drainage Systems For Room-And-Pillar Operations, Yanbei Wang, Jan M. Mutmansky

U.S. Mine Ventilation Symposium

The analysis of the economics of methane drainage operations in traditional room-and-pillar coal mining operations is the primary emphasis of this presentation. The paper analyzes the economic effects of ventilation costs versus drainage costs as a means of handling the methane in a hypothetical room-and-pillar operation. However, the effects of downtime savings due to methane reduction in the air stream and the impacts of marketing the methane are also studied. Comparisons are then made with the economics of drainage in longwall mining.

Design Of Methane Drainage Systems To Reduce Mine Ventilation Requirements, Michael D. Zuber, Charles M. Boyer Ii, Denise L. Delozier

U.S. Mine Ventilation Symposium

There are numerous proven methods to drain methane from coal seams in coal mines. These systems include vertical wells drilled ahead of mining, horizontal boreholes, gob wells, and others. However, these drainage systems are not typically applied properly to optimize gas recovery and minimize the cost of ventilation to the mine. This lack of optimization generally occurs due to the large up-front costs associated with the drainage systems and the lack of knowledge regarding the drainage technology. This results in the mine having a "reactive" response to methane drainage issues as opposed to a "pro-active" plan for handling methane drainage. …

Methane Ignitions On Roof Bolters In Underground Coal Mines, John E. Urosek, William J. Francart

U.S. Mine Ventilation Symposium

Although not as frequent in nature as ignitions on continuous miner or longwall faces, ignitions of methane on roof bolters have caused serious injuries to underground coal miners. After reviewing the accident reports for all roof bolter ignitions from 1981 to 1998, a summary of the forty-one accidents has been developed. Of interest in the database is the ignition source, method of face ventilation, local velocity, methane liberation, size of the methane body ignited, and the duration of the flame. Three example ignitions are included.

Evaluation Of A Continuous Miner Half-Curtain Dust Control System In A South African Underground Coal Mine, Bharath K. Belle, J. J. L. Du Plessis

U.S. Mine Ventilation Symposium

The issues of public health and safety in the mining industry have been dealt with around the world through the intervention of governments. In 1997 the South African Department of Minerals and Energy (DME) sent out a directive to reduce the dust concentration level to /m³ at the operator's position for the sampling period. The reasons for the difficulty with compliance are: long headings up to 35m, inherently high dust generation rates of coal, and the increased use of highly mechanized equipment. A project was formulated under SIMRAC auspices with the title of "Underground Mechanical Miner Environmental Control" to …

Effectiveness Of Cabs For Dust And Silica Control On Mobile Mining Equipment, Joseph J. Garcia, Ronald E. Gresh, Mary Beth Gareis, Robert A. Haney

U.S. Mine Ventilation Symposium

The Mine Safety and Health Administration (MSHA) has conducted a study to evaluate the effectiveness of cabs for controlling silica dust exposure during operation of mobile mining equipment. This study focused on bulldozers, front -end loaders and haul trucks, was conducted at surface coal mining operations and underground metal and nonmetal mining operations. Each piece of equipment tested was equipped with a cab. The vehicles sampled were from a range of manufacturers having different types of filter media and air intake configurations. The purpose of this study was to determine the reduction of dust and silica exposure that could be …

Niosh/Nci Study Of Exposure To Diesel Exhaust In Underground Mines — An Industry Perspective, Christopher J. Pritchard

U.S. Mine Ventilation Symposium

In 1992, the National Institute For Occupational Safety and Health (NIOSH) initiated a study, funded by the National Cancer Institute (NCI), to evaluate the health effects, if any, involving underground miners exposure to diesel exhaust. An industry organization, the Methane Awareness Research Group (MARG) already in place to respond to gassy mine related issues, was redirected to work with diesel concerns. In 1995, NIOSH released a draft protocol and feasibility assessment, indicating its intent to initiate s study at 14 underground mines, some of which were operated by MARG members. After considerable debate on the study protocol, in-mine industrial hygiene …

A Mathematical Model Of Heat Transfer In Partially Insulated Airways In Deep, Frozen Ground Placer Mines, Sukumar Bandopadhyay, Hanguang Wu, Michael G. Nelson

U.S. Mine Ventilation Symposium

Large seasonal variations in the temperature of the ventilating air in mines in the arctic cause changes in the original thermal field through heat and mass exchanges between the air and the surrounding medium. These thermal interactions have major influence on climatic quality as well as on the stability of the mine openings. Thawing of walls and roof in mine airways can be reduced by various types of thermal-insulation. Application of thermal-insulation prevents deep thawing of the rockmass surrounding an airway. In this case, the mechanism of heat transfer around a frozen, underground airway would be much different. A model …

Table Of Contents, Multiple Authors

U.S. Mine Ventilation Symposium

No abstract provided.

Successive Galerkin Approximation Of A Nonlinear Optimal Attitude Control, Timothy Mclain, Randal W. Beard, Johnathan Lawton

Faculty Publications

This paper presents the application of the successive Galerkin approximation (SGA) to the Hamilton-Jacobi-Bellman equation to obtain solutions of the optimal attitude control problem. Galerkin's method approximates the value function by a truncated Galerkin series expansion. To do so, a truncated Galerkin basis set is formed. A sufficient number of functions must be included in this Galerkin basis set in order to guarantee that the solution will be a stabilizing control. By increasing the size of the Galerkin basis the quality of the approximation is improved at the cost of rapid growth in the computation load of the SGA. A …

Acuta Enews June 1999, Vol.28, No. 6

ACUTA Newsletters

In This Issue

Winners Announced in Student Papers Contest

Conference Offers Many Choices

Dues Notices Mailed

Does It Make Sense?

Board Report

Share Your Expertise

DC at a Glance

Positions Available

Welcome New Members

A Five-Year Development Plan For The California Aviation Database, H.-S. Jacob Tsao

Faculty Publications

The California Aviation Database (CAvD) project was suggested by Caltrans Aeronautics Program to fulfill a need of the planners involved in aviation system planning and programming activities to locate and access aviation data and information in an efficient and comprehensive way. CAvD is being implemented in the form of an Internet website and is currently intended as a five-year project. However, the development can be accelerated, and the duration will depend on the available resources. CAvD is a joint project between the National Center of Excellence for Aviation Operations Research (NEXTOR) and the California Department of Transportation (Caltrans). Its primary …

Introduction: The Challenge Of Risk Communication In A Democratic Society, Richard C. Rich, Robert J. Griffin, Sharon M. Friedman

RISK: Health, Safety & Environment (1990-2002)

The symposium editors review key issues concerning the relationship between risk communication and public participation.

Flight Physician - June, 1999, Civil Aviation Medical Association

Browse all Civil Aviation Medical Association Newsletters

A sixteen page newsletter of the Civil Aviation Medical Association. The newsletter provided news about civil aviation medicine and information related to the organization.

User Evaluation Of Prototype Pv Equipment For Disasters, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

Natural disasters, such as hurricanes, floods and tornados, can happen at any time, destroying homes and businesses. One such disaster, Hurricane Andrew, devastated South Florida in 1992, leaving several hundred thousand people homeless. Many people were without electrical service, functional water and sewage systems, communications and medical services for days and weeks in the aftermath of the storm. Emergency management teams, the military, and countless public and private organizations staged a massive relief effort.

In response to the Hurricane Andrew disaster, the staff at the Florida Solar Energy Center, with assistance from Sandia National Laboratories, transported PV-powered equipment to Miami …

Installing Photovoltaic Systems: A Question And Answer Guide For Solar Electric Systems, Florida Solar Energy Center, Fsec Photovoltaic Division

FSEC Energy Research Center®

This Question and Answer Guide for Solar Electric Systems addresses general considerations about photovoltaics (PV) technology and requirements for installing photovoltaic power systems, including building-integrated applications. Contained in this guide are commonly asked questions about the technology, and responses based on current state-of-the-art equipment and industry design practice.

Program Plan For Photovoltaic Buildings In Florida, Florida Solar Energy Center, Gerard Ventre

FSEC Energy Research Center®

This document outlines plans developed by the Florida Solar Energy Center (FSEC) to support photovoltaic (PV) building applications in the State through the next decade. Implementation of the plan will be a collaborative effort among the Florida Energy Office (FEO) of the Department of Community Affairs, Sandia National Laboratories (SNL), the photovoltaic industry, nine end-user groups, and FSEC.

Decision Making Under Interval Probabilities, Ronald R. Yager, Vladik Kreinovich

Departmental Technical Reports (CS)

If we know the probabilities p(1),...,p(n) of different situations s1,...,sn, then we can choose a decision Ai for which the expected benefit C(i)=p(1)*c(i,1)+...+p(n)*c(i,n) takes the largest possible value, where c(i,j) denotes the benefit of decision Ai in situation sj. In many real life situations, however, we do not know the exact values of the probabilities p(j); we only know the intervals [p-(j),p+(j)] of possible values of these probabilities. In order to make decisions under such interval probabilities, we would like to generalize the notion of expected benefits to interval probabilities. In this paper, we show that natural requirements lead to …

Fuzzy/Probability ~ Fractal/Smooth, Hung T. Nguyen, Vladik Kreinovich, Berlin Wu

Departmental Technical Reports (CS)

Many applications of probability theory are based on the assumption that, as the number of cases increase, the relative frequency of cases with a certain property tends to a number - probability that this property is true. L. Zadeh has shown that in many real-life situations, the frequency oscillates and does not converge at all. It is very difficult to describe such situations by using methods from traditional probability theory. Fuzzy logic is not based on any convergence assumptions and therefore, provides a natural description of such situations. However, a natural next question arises: how can we describe this oscillating …

Crosstalk And Image Uniformity In Passive Matrix Polymer Led Displays, David Braun, J. Rowe, G. Yu

Electrical Engineering

Passive matrix displays based on polymer and organic light-emitting diodes suffer from crosstalk, when the emission of light from one pixel depends on the operation of another pixel. We use circuit simulation in order to explain the causes of crosstalk and to quantify the consequences. This work analyzes how crosstalk arises from electrode resistance, pixel leakage current, and the location of faulty pixels. All factors influence both image uniformity and the power consumption of the display.

Possible Explanations Of Phase Transitions In Highway Traffic, C.F. Daganzo, M.J. Cassidy, Robert L. Bertini

Civil and Environmental Engineering

It is shown that all the phase transitions in and out of freely flowing traffic reported earlier for a German site could be caused by bottlenecks, as are all the transitions observed at two other sites examined here. The evidence suggests that bottlenecks cause these transitions in a predictable way, and does not suggest that stoppages (jams) appear spontaneously in free flow traffic for no apparent reason. It is also shown that many of the complicated instability phenomena observed at all locations can be explained qualitatively in terms of a simple Markovian theory specific to traffic that does not necessarily …

Multi-Resolution Techniques In The Rules-Based Intelligent Control Systems: A Universal Approximation Result, Yeung Yam, Hung T. Nguyen, Vladik Kreinovich

Departmental Technical Reports (CS)

Intelligent control is a very successful method of transforming expert knowledge of control rules (formulated in terms of natural language, like "small") into a precise control strategy. It has led to many spectacular applications, ranging from appliances to automatic subway control to super-precise temperature control on a Space Shuttle mission.

It is known that fuzzy control is a universal approximator, i.e., that it can approximate every possible control strategy within an arbitrary accuracy. One of the main problems of fuzzy control is that the number of rules which are necessary to represent a given control strategy with a given accuracy, …

Multi-Resolution Methods In Non-Destructive Testing Of Aerospace Structures And In Medicine, Roberto Osegueda, Yohans Mendoza, Olga Kosheleva, Vladik Kreinovich

Departmental Technical Reports (CS)

A fault in an aerospace structure can lead to catastrophic consequences; therefore, it is extremely important to test these structures regularly. Thorough testing of a huge aerospace structures results in a large amount of data, and processing this data takes a lot of time. To decrease the processing time, we use a "multi-resolution" technique, in which we first separate the data into data corresponding to different vibration modes, and then combine these data together. There are many possible ways to transform each mode's data into the probability of a fault, and many possible way of combining these mode-based probabilities; different …