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Articles 361 - 390 of 566

Full-Text Articles in Engineering

A Continually Online Trained Neurocontroller For Excitation And Turbine Control Of A Turbogenerator, Ganesh K. Venayagamoorthy, Ronald G. Harley Jan 2001

A Continually Online Trained Neurocontroller For Excitation And Turbine Control Of A Turbogenerator, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

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Dual Heuristic Programming Excitation Neurocontrol For Generators In A Multimachine Power System, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley Jan 2001

Dual Heuristic Programming Excitation Neurocontrol For Generators In A Multimachine Power System, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

The design of optimal neurocontrollers that replace the conventional automatic voltage regulators for excitation control of turbogenerators in a multimachine power system is presented in this paper. The neurocontroller design is based on dual heuristic programming (DHP), a powerful adaptive critic technique. The feedback variables are completely based on local measurements from the generators. Simulations on a three-machine power system demonstrate that DHP based neurocontrol is much more effective than the conventional PID control for improving dynamic performance and stability of the power grid under small and large disturbances. This paper also shows how to design optimal multiple neurocontrollers for …

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Experimental Studies With Continually Online Trained Artificial Neural Network Identifiers For Multiple Turbogenerators On The Electric Power Grid, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley Jan 2001

Experimental Studies With Continually Online Trained Artificial Neural Network Identifiers For Multiple Turbogenerators On The Electric Power Grid, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

The increasing complexity of a modern power grid highlights the need for advanced system identification techniques for effective control of power systems. This paper provides a new method for nonlinear identification of turbogenerators in a 3-machine 6-bus power system using online trained feedforward neural networks. Each turbogenerator in the power system is equipped with a neuro-identifier, which is able to identify its particular turbogenerator and the rest of the network to which it is connected from moment to moment, based on only local measurements. Each neuro-identifier can then be used in the design of a nonlinear neurocontroller for each turbogenerator …

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A Nonlinear Voltage Controller With Derivative Adaptive Critics For Multimachine Power Systems, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley Jan 2001

A Nonlinear Voltage Controller With Derivative Adaptive Critics For Multimachine Power Systems, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

Based on derivative adaptive critics, a novel nonlinear optimal voltage/excitation control for a multimachine power system is presented. The feedback variables are completely based on local measurements. Simulations on a three-machine system demonstrate that the nonlinear controller is much more effective than the conventional PID controller equipped with a power system stabilizer for improving dynamic performance and stability under small and large disturbances.

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Excitation And Turbine Neurocontrol With Derivative Adaptive Critics Of Multiple Generators On The Power Grid, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley Jan 2001

Excitation And Turbine Neurocontrol With Derivative Adaptive Critics Of Multiple Generators On The Power Grid, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

Based on derivative adaptive critics, neurocontrollers for excitation and turbine control of multiple generators on the electric power grid are presented. The feedback variables are completely based on local measurements. Simulations on a three-machine power system demonstrate that the neurocontrollers are much more effective than conventional PID controllers, the automatic voltage regulators and the governors, for improving the dynamic performance and stability under small and large disturbances

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A Committee Of Neural Networks For Automatic Speaker Recognition (Asr) Systems, Viresh Moonasar, Ganesh K. Venayagamoorthy Jan 2001

A Committee Of Neural Networks For Automatic Speaker Recognition (Asr) Systems, Viresh Moonasar, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

This paper describes how the results of speaker verification systems can be improved and made robust with the use of a committee of neural networks for pattern recognition rather than the conventional single-network decision system. It illustrates the use of a supervised learning vector quantization neural network as the pattern classifier. Linear predictive coding and cepstral signal processing techniques are utilized to form hybrid feature parameter vectors to combat the effect of decreased recognition success with increased group size (number of speakers to be recognized)

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Distortional Buckling Of Cold-Formed Stainless Steel Compression Members, A. Liang, G. J. Van Den Berg, Rudolph Laubscher Oct 2000

Distortional Buckling Of Cold-Formed Stainless Steel Compression Members, A. Liang, G. J. Van Den Berg, Rudolph Laubscher

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

In this paper the critical local buckling strength of cold-formed stainless steel compression members, with special emphasis on the method developed by Lau and Hancock for distortional buckling is discussed. Cold-formed stainless steel channel and I-section members under axial compression in distortional buckling are analysed. A control experiment is carried out for comparing analytical methods with a finite element method and experimental values.

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Eccentrically Loaded Bolted Connections For Type 304 And 3cr12 Stainless Steel Lipped Channels, P. Van Tonder, Q. C. Oliphant, G. J. Van Den Berg Oct 2000

Eccentrically Loaded Bolted Connections For Type 304 And 3cr12 Stainless Steel Lipped Channels, P. Van Tonder, Q. C. Oliphant, G. J. Van Den Berg

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

In this paper the results of a study on eccentrically loaded bolted connections in lipped channels are presented. The steels chosen for this study are AISI Type 304 and Type 3CR12 stainless steel. It is concluded in this investigation that an acceptable prediction of the strength of eccentrically loaded bolted connections of stainless steel lipped channels may be obtained through the combination between the eccentric loaded equation and the normal bolted connection equations for stainless steel.

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Two Separate Continually Online Trained Neurocontrollers For Excitation And Turbine Control Of A Turbogenerator, Ganesh K. Venayagamoorthy, Ronald G. Harley Jan 2000

Two Separate Continually Online Trained Neurocontrollers For Excitation And Turbine Control Of A Turbogenerator, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents the design of two separate continually online trained (GOT) artificial neural network (ANN) controllers for excitation and turbine control of a turbogenerator connected to the infinite bus through a transmission line. These neurocontrollers augment/replace the conventional automatic voltage regulator and the turbine governor of a generator. A third COT ANN is used to identify the complex nonlinear dynamics of the power system. Results are presented to show that the two COT ANN controllers can control turbogenerators under steady state as well as transient conditions and thus allow turbogenerators to operate more closely to their steady state stability …

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Comparison Of A Heuristic Dynamic Programming And A Dual Heuristic Programming Based Adaptive Critics Neurocontroller For A Turbogenerator, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley Jan 2000

Comparison Of A Heuristic Dynamic Programming And A Dual Heuristic Programming Based Adaptive Critics Neurocontroller For A Turbogenerator, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents the design of a neurocontroller for a turbogenerator that augments/replaces the conventional automatic voltage regulator and the turbine governor. The neurocontroller uses a novel technique based on the adaptive critic designs with emphasis on heuristic dynamic programming (HDP) and dual heuristic programming (DHP). Results are presented to show that the DHP based neurocontroller is robust and performs better than the HDP based neurocontroller, as well as the conventional controller, especially when the system conditions and configuration changes.

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Comparison Of Text-Dependent Speaker Identification Methods For Short Distance Telephone Lines Using Artificial Neural Networks, Ganesh K. Venayagamoorthy, N. Sundepersadh Jan 2000

Comparison Of Text-Dependent Speaker Identification Methods For Short Distance Telephone Lines Using Artificial Neural Networks, Ganesh K. Venayagamoorthy, N. Sundepersadh

Electrical and Computer Engineering Faculty Research & Creative Works

The transition to democracy in South Africa has brought with it certain challenges. The main challenge is to get rid of crime and corruption. The paper presents a technique to combat white-collar crime in telephone transactions by identifying and verifying speakers using artificial neural networks (ANNs). Results are presented to show that speaker identification is feasible and this is illustrated with two different types of ANN architectures and with two different types of characteristic features as inputs to ANNs.

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Decentralized Online Neuro-Identification Of Turbogenerators In A Multi-Machine Power System, Ganesh K. Venayagamoorthy, Ronald G. Harley Jan 2000

Decentralized Online Neuro-Identification Of Turbogenerators In A Multi-Machine Power System, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a new and a novel technique based on Artificial Neural Networks (ANNs) for nonlinear model of turbogenerators in a multi-machine power system. Only local measurements are required by each ANN in this new method, and hence it is called decentralized neuro-identificiation. Each turbogenerator in the power system is quipped with an ANN which is able to identify (or model) its particular turbogenerator from moment to moment This information can then be used by a second ANN at each generator to enable effective control of the nonlinear non-stationary process under all operating conditions. Simulation results are presented in …

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Adaptive Critic Based Neurocontroller For Turbogenerators With Global Dual Heuristic Programming, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley Jan 2000

Adaptive Critic Based Neurocontroller For Turbogenerators With Global Dual Heuristic Programming, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

Turbogenerators are nonlinear time varying systems. This paper presents the design of a neurocontroller for such a turbogenerator that augments/replaces the traditional automatic voltage regulator (AVR) and the turbine governor using a novel technique based on the adaptive critic designs (ACDs) with emphasis on global dual heuristic programming (GDHP). Simulation results are presented to show that the neurocontroller derived with the GDHP approach is robust and its performance is better when compared with that derived with other neural network technique, especially when system conditions and configuration changes.

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A Comparison Of Air Leakage Prediction Techniques For Auxiliary Ventilation Ducting Systems, A. D. Stewart Gillies, Hsin Wei Wu Jun 1999

A Comparison Of Air Leakage Prediction Techniques For Auxiliary Ventilation Ducting Systems, A. D. Stewart Gillies, Hsin Wei Wu

U.S. Mine Ventilation Symposium

This paper briefly reviews prediction techniques for determination of leakage and friction along auxiliary ventilation ducting systems. In order to compare various prediction techniques that have been developed over the past, a macroscopic investigation of air leakage and friction resistance of auxiliary ventilation ducting systems has been undertaken. Measurements were conducted on 450 and 915 mm diameter fabric ducting over 100 m duct length to determine frictional resistances and the extent of leakage. Due to the high degree of accuracy required and the large volume of data that needed to be collected, electronic pressure transducers were used with computer for …

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Controlled Recirculation In Deep South African Gold Mines, Mark Butterworth Jun 1999

Controlled Recirculation In Deep South African Gold Mines, Mark Butterworth

U.S. Mine Ventilation Symposium

Despite the many advantages and potential benefits of using controlled recirculation in Deep South African gold mines the strategy has found little favour. Indeed, controlled recirculation of air is at present rarely considered as an option in the planning and implementation of these underground ventilation systems. This paper broadly examines controlled recirculation, the benefits and advantages that could accrue from its use, reasons that may detract from its use and some solutions for addressing shortcomings. A brief historical review of controlled recirculation in the context of the South African gold mining industry is given. The advantages, which could result from …

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Environ 2.5 — A Mine Ventilation And Cooling Network Simulation Tool, W. M. Marx Jun 1999

Environ 2.5 — A Mine Ventilation And Cooling Network Simulation Tool, W. M. Marx

U.S. Mine Ventilation Symposium

As mining operations progress, ore reserves are depleted and alternative are almost invariably found at increasing depth and a host of attendant difficulties in this regard face· the mine operator. Most significant among these is the control of the increasingly hostile environment encountered at depth in terms of both ground behaviour and the increasing hot environment. To enable the practical and economical design of mine ventilation and cooling systems, ventilation practitioners need effective and efficient tools to perform their duty. One such tool is the Environ 2.5, an interactive network simulation program that allows for the simultaneous simulation of airflow …

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Management Of Mine Explosion Risks, Jan J. L. Du Plessis, J. W. Oberholzer Jun 1999

Management Of Mine Explosion Risks, Jan J. L. Du Plessis, J. W. Oberholzer

U.S. Mine Ventilation Symposium

The management of explosions in the underground mining environment has been a high priority for managers since the turn of the century. In the early 1900s explosions, worldwide, reached catastrophic dimensions. In a number of large explosions more than 1000 people have died. In the early years of research, the basics of why explosions occurred were investigated and the participation of coal dust in underground coal mine explosions was proved. Taffanel, a French researcher, was one of the pioneers in establishing the use of stone dust and was instrumental in the design and development of the first stone-dust barriers. Throughout …

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Performance Assessment Of A Multi-Stage Cooling System At San Manuel Mine, Kuda R. Mutama Jun 1999

Performance Assessment Of A Multi-Stage Cooling System At San Manuel Mine, Kuda R. Mutama

U.S. Mine Ventilation Symposium

This paper describes the mine ventilation cooling system at San Manuel Mine, which has evolved as new deeper and hotter working levels were added to the mine, between 1979 -1997. The expansion philosophy was based on utilizing existing facilities, providing lower capital cost and operational convenience. The cooling system is comprised of three surface chillers of 10.55 Megawatts (3,000 tons) total cooling capacity. Cooling towers, also located on surface, ultimately reject all the heat from underground system. The chilled water is pumped to a shell and tube heat exchanger station located 915 metres underground in a high pressure circulating water …

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Rapid Extinguishing Of Sponcom Fires In Underground Mines, Zygmunt Kajdasz, George Zieba Jun 1999

Rapid Extinguishing Of Sponcom Fires In Underground Mines, Zygmunt Kajdasz, George Zieba

U.S. Mine Ventilation Symposium

The main purpose presented in this paper is to present active and passive methods to fight a sponcom fire. The active method uses an inert gas generator called the GAG while the passive method is through the use of ventilation software. In most sponcom situations a combination of these two methods results in rapid extinguishing of the overheated areas. The presented software allows for accurate and "real time" analysis of the ventilation network. Application of the GAG has been proven on many occasions as an effective means of large volumes of mine atmosphere.

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Flammable Gas Emissions In South African Gold And Platinum Mines Review Of Incidents And Accidents, A. P. Cook, C. F. Meyer, K. Balt Jun 1999

Flammable Gas Emissions In South African Gold And Platinum Mines Review Of Incidents And Accidents, A. P. Cook, C. F. Meyer, K. Balt

U.S. Mine Ventilation Symposium

Flammable gas emissions are relatively common and widespread across the South African gold and platinum mines, but a general lack of awareness has lead to an increase in flammable gas related accidents and fatalities over the last ten years. The gas is usually a mixture of hydrocarbons C1 to C4 with hydrogen, each in varying quantities, with methane and hydrogen predominant. The three most common causes leading to gas accidents are changes to the ventilation, lack of testing for gas, and contraband, with gas ignitions caused by contraband and illegal tampering with caplamps. Development work accounts for 70 percent of …

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A Proposed New Method To Determine The Effectiveness Of In-Heading Methane Control, F. J. Van Zyl Jun 1999

A Proposed New Method To Determine The Effectiveness Of In-Heading Methane Control, F. J. Van Zyl

U.S. Mine Ventilation Symposium

Various methods have been derived to determine the effectiveness with which ventilation systems clears headings of methane in a bord-and-pillar sections. A problem with applying these methods in underground sections is that the either require the face-area air quantity to be measured, which is virtually impossible in South African collieries, or they were developed for test galleries, making it difficult to use in production sections. Taking this into consideration the methane safety index (MSI) method was developed. The method utilizes methane data recorded around an active continuous miner (CM) and an activity log of cm operations to quantitatively assess methane …

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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 Jun 1999

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 …

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Axial Fan Monitoring By Pressure Transients Close To The Blades, A Preliminary Study, Ian Loomis, Shaun Ramsay Jun 1999

Axial Fan Monitoring By Pressure Transients Close To The Blades, A Preliminary Study, Ian Loomis, Shaun Ramsay

U.S. Mine Ventilation Symposium

As the axial fan blades move within the fan case pressure transients are developed, which can be measured and qualified by a fixed point monitor. The nature of the pressure transient pattern observed close to the fan blade varies with the location on the fan performance curve. Measurement of the pressure fluctuation around the fan blade ring reveals the minute variation in pressure associated with the movement of the air within the fan. Such observations could be the basis for an on-line fan monitoring system based on the acoustic emissions from the fan blade. This paper describes a preliminary study …

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Performance Of Distributed Bagged Stone Dust Barrier In Combating Coal-Dust Explosions, Jan J. L. Du Plessis, Pierre S. Vassard Jun 1999

Performance Of Distributed Bagged Stone Dust Barrier In Combating Coal-Dust Explosions, Jan J. L. Du Plessis, Pierre S. Vassard

U.S. Mine Ventilation Symposium

The Kloppersbos Research Facility of the CSIR's Division of Mining Technology has developed a new method of building stone dust barriers. The new barrier makes use of a previous concept of containing stone dust in a bag, but incorporates a new method of rupturing the bag. This was achieved by adapting the closing mechanism and by balancing the stone dust content with the void in the bag. The bagged barrier was extensively tested in the 200-m test gallery. During these tests, it became evident that these bags could be made to rupture and spread stone dust when subjected to smaller …

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An Integrated Strategy For Emergency Egress From An Underground Metal Mine, Rick Brake Jun 1999

An Integrated Strategy For Emergency Egress From An Underground Metal Mine, Rick Brake

U.S. Mine Ventilation Symposium

The fact that major fires are rare events in underground metal mines means there is often little on-site experience in dealing with these situations. Elaborate strategies that rely on a high degree of training at all levels to be effective are likely to fail, especially with the trend in Australia towards smaller mines and "fly in-fly out" operations. A robust strategy is required. The key items in such a strategy are: early detection and warning of personnel, personal belt-worn oxygen-generating self-rescuers, high integrity escape routes and self-contained refuge stations, simple procedures, reliable personnel ''tagging" systems and sufficient, trained, search and …

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Characteristics Of Airborne Dust In The Return Airways Of The Mechanized Longwall Face, Tevfik Güyagüler, Sinan Keskin Jun 1999

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 …

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Increased Methane Emissions For Mechanical Miners Working In Burnt Coal, A. P. Cook Jun 1999

Increased Methane Emissions For Mechanical Miners Working In Burnt Coal, A. P. Cook

U.S. Mine Ventilation Symposium

An intensive research programme has quantified the methane conditions around mechanical miners in production conditions. Methane seam gas contents show an increase of up to 26 times when mining burnt coal compared with normal increase in emission rates. Coal seam methane contents at the face increased from 1 m3/t to 6m3/t in one section, and from 0.1 m3/t to 2.6 m3/t in another. Emission rates from burnt coal were as high as 300 lit/min as it was mined. These increases in content and emission occur immediately after cutting into the burnt coal. …

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Personal Cooling In Hot Workings, Michael A. Tuck Jun 1999

Personal Cooling In Hot Workings, Michael A. Tuck

U.S. Mine Ventilation Symposium

The number of mines experiencing climatic difficulties worldwide is increasing. In a large number of cases these climatic difficulties are confined to working areas only or to specific locations within working areas. Thus the problem in these mines can be described as highly localised, due to a large extent not to high rock temperatures but due to machine heat loads and low airflow rates. Under such situations conventional means of controlling the climate can be inapplicable and/or uneconomic. One possible means of achieving the required level of climatic control, to ensure worker health and safety whilst achieving economic gains, is …

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Ccfss News February 1999, Wei-Wen Yu Center For Cold-Formed Steel Structures Feb 1999

Ccfss News February 1999, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Newsletters (1999 - 2008)

No abstract provided.

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Predicting The Unconfined Compressive Strength Of The Breathitt Shale Using Slake Durability, Shore Hardness And Rock Structural Properties, Engin C. Koncagül, Paul M. Santi Jan 1999

Predicting The Unconfined Compressive Strength Of The Breathitt Shale Using Slake Durability, Shore Hardness And Rock Structural Properties, Engin C. Koncagül, Paul M. Santi

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Compressive strength is the most widely used design parameter in the construction industry and in rock engineering. For example, Bieniawski [Bieniawski, Z.T., Estimating the strength of rock materials, Is. J. S. Afr. Inst. Min. Metall., 1974, 74, 312-320.] reported that mining engineers request the uniaxial compressive strength (UCS) more often than any other rock property. However, standards set for specimen preparation are very demanding. Therefore, it is quite difficult and sometimes impossible to fulfill these requirements using weak rocks and especially shales. This paper evaluates the use of the slake durability and Shore hardness tests to estimate UCS, based on …

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