Article

FACE TECHNOLOGY IN GERMANY'S COALMINES IN 1985.

June 1986

Authors:

In 1985, the German coal mining industry retained its No. 1 position in the world. A review of the machineries that made this achievement possible includes; use of winning machines and power supports; use of drum shearer loaders for cutting winning; increase in the percentage of twin centre strand face conveyors; increase in the production percentage of pneumatically stowed faces. The report ends with a brief description of the wide range of research and development which was carried out in 1985 in the various sectors of face technology.

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ResearchGate has not been able to resolve any references for this publication.

Article

Secondary Breaking in Underground Mines.

April 1987

W. Helms

The terms 'boulder breaking', 'secondary breaking' and 'preliminary breaking' are defined. The author analyses the causes for deficiencies in raw ore lump size. The following methods for secondary breaking are discussed: manual breaking, breaking by winning machinery and loaders, blasting, pneumatic and hydraulic breakers, mobile crushers, stationary and semi-mobile crushers. The paper concludes ... [Show full abstract] with an evaluation of methods and economic considerations.

Article

A Study on Drum Cutting Properties with Full-scale Experiments and Numerical Simulations

September 2017 · Measurement

In order to investigate the properties of cutting loads on shearer drum, a series of full-scale shearer drum cutting tests were conducted in the National Energy Coal Mining Machinery Equipment Research and Design Center of China. The pick forces and the torque acting on the drum were measured and recorded under different cutting conditions by the strain sensors that were embedded in the cutting ... [Show full abstract] picks. Besides, an attempt was made to simulate the shearer drum cutting process. For this purpose, a computer program named Particle Flow Code in three dimensions (PFC3D) based on discrete element method (DEM) was used. The rock sample was models by graded particle assemblies and the micro-properties were calibrated by modeling the uniaxial compressive strength tests. The cutting process for the front and back drums with different traction speeds were simulated with this model. The torque of drums and forces of each pick were obtained during the simulation. Reasonable agreement and significant correlations were found between experiment and numerical simulation in terms of cutting forces of picks and the mean torque of the drums. The specific energy increased with the increase of traction speed in experiments, which was reproduced well in numerical simulation. Moreover, according to the analysis in frequency domain, the vibration of drum torque consists of components with multiple frequencies below 50 Hz, which is observed in both experiment and simulation. Therefore, numerical simulation by PFC3D is an easier, faster and reasonable method in the prediction of drum cutting load and design of shearer drum.

Article

Underground coal waste disposal: Can it be cost effective. [Considers 10 different methods of transp...

January 1983

Gaffney

This paper examines the feasibility of returning coal mine wastes to the mined-out areas, as encouraged by PL 95-87, the ''Surface Mining Control and Reclamation Act of 1977'' (SMCRA). Reviews a National Academy of Sciences report which identified alternative backfilling methods. Presents diagram of mechanical backfilling with gravity and mechanical transport, and tables of existing underground ... [Show full abstract] mine waste disposal methods and a summary of technical feasibility of alternative disposal systems. Evaluated systems include gravity disposal with mechanical surface transport; gravity disposal with mechanical in-mine transport; complete mechanical disposal; mechanical disposal with gravity surface to underground transport; direct hydraulic disposal; hydraulic disposal with natural head; hydraulic disposal with artificial head; pneumatic disposal with mechanical surface transport; pneumatic disposal with mechanical surface and in-mine transport; and hydropneumatic disposal. The Office of Surface Mining is mandated by PL 95-87 to promote research for the development of underground disposal.

Article

Full-text available

The concept of system for chips production need to work demo CHP plant in company 'AGROSAVA' from Si...

January 2014 · Tehnika

Aleksandar Dedic

In this paper according to the calculation of chips productivity needs for gasification in the demo CHP plant for co-generation: electricity and heat, chippers were analyzed due to: the type of mobility, running for chipping and the method of delivering chips to temporary yard. The plant was planned to generate electricity power up to 200kWelec. First, in consideration were taken the chippers ... [Show full abstract] with medium capacity, which mainly served for chipping brushwood and leaves that remain after harvest plantations on mostly flat terrain and parks. Later, the comparative characteristics of the world's three largest manufacturers of machinery for the production of wood chips significantly larger amounts (up to 30m3/h) were given. These chippers were particularly suitable for the higher density of crops and stationed yard, in which brushwood would be brought and chip. At the end, the types of convective dryers were analyzed that could be successfully used for drying wood chips (drum and pneumatic dryer) and based on the calculation proposed the types of dryers that were available in the local market.

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Article

Effective Ball Handling and Control in Robot Soccer

January 1970

An autonomous soccer-playing robot was designed and constructed as part of the electrical engineering senior project at Brigham Young University. Unique physical features enable ball handling abilities. A front-side rotating drum retains the ball by applying backspin. A pneumatic kicker allows for fast accurate kicks. Robot movement control is performed by three different systems. The low-level ... [Show full abstract] velocity controller ensures output of desired forward and angular velocities. The position controller is used to match the robot's position with a desired position. Path generation directs the robot along a desired path at a specified velocity. The locations of the robots and ball on the soccer field is determined by the vision system. This document is a formal description of the unique designs and construction of the our team's robot.

Article

An optical slit mechanism

December 2002 · Journal of Scientific Instruments

R V Jones

A symmetrically opening slit mechanism, particularly suitable for infra-red spectrometers, is described. It employs parallel spring movements, operates for widths from 1 to 2 000 μ and is suitable for use with curved jaws. Its operating torque is about 50 g cm which, with its rapid response and freedom from backlash, makes it suitable for automatic control. The jaws remain parallel to within ... [Show full abstract] about 3 sec, and the mid-line of the slit does not drift more than about 2 μ. Hysteresis between the driving micrometer drum and the measured slit width amounts to 0.2-0.3 μ, and may be due to an oil film. The slit jaws can be set so close together as to polarize the transmitted light completely. The slit mechanism, with a suitable rotational movement, has been applied to a twin-beam infra-red spectrometer; it has been demonstrated that entrance and exit slits must be alined to within a few seconds if satisfactory balance of the twin beams is to be achieved. An appendix describes a new all-spring reversing mechanism which enables the slit width to be controlled to better than 0.05 μ, and which is apparently completely free from hysteresis.

Article

On the low frequency in-plane forced vibrations of pneumatic tyre/wheel/suspension assemblies

January 1997 · Vehicle System Dynamics

The paper contains an interim report on a research project into the longitudinal vibrations of vehicles. The aim is to improve understanding of the process by which tyres come to vibrate by rolling along surfaces which may be smooth or profiled and the transmission of the vibration into the vehicle cabin. A description of a specially designed rig is given. This allows control of the boundary ... [Show full abstract] conditions of a tyre/wheel assembly which runs on a rotating drum, and allows forcing to be applied by an electromagnetic shaker to the hub in the vertical or longitudinal direction. A measurement scheme has been implemented to record forces and translational and spin accelerations of the hub. A mathematical model of the rig has been built using the multibody modelling software Autosim. The tyre is represented as a hub and rigid circular ring with translational and rotational freedoms between them. The hub is mounted in a suspension system allowing it translational and spin freedoms. The model and the measurements are used to generate frequency responses, and a parameter identification scheme is being followed to obtain a best fit of the theoretical results to the experimental results in the frequency range up to about 100 Hz. Vibration spectra and comparative experimental and theoretical frequency response functions are included.

Article

Fail-safe control system for a mine methane pipeline

January 1970

The Bureau of Mines has designed and put into operation a fail-safe control system for use in underground coal mines equipped with methane drainage pipelines. This control system can detect certain unsafe conditions and respond by automatically shutting off the flow of methane from the degasification borehole to the drainage pipeline. Methane flow is shut off when the methane content in the ... [Show full abstract] return airways reaches a predetermined level (typically 1.5%), when the methane drainage pipeline is ruptured by roof fall, or when there is an electric power failure. The fail-safe control system was designed using commercially available components and a methane analyzer system previously developed by the Bureau. The fail-safe system consists of a unit that combines a shutoff valve and pneumatic valve actuator, and electronic and mechanical equipment designed to detect hazards and effect shutdown. The fail-safe control system was designed to meet regulatory requirements issued by the Mine Safety and Health Administration (MSHA), Department of Labor, and State regulatory bodies for the safe operation of underground methane pipelines used for mine degasification. MSHA has inspected and tested this system and permitted its use in two mines. The Bureau installed the fail-safe system in two working coal mines, where successful performance has been demonstrated.

Conference Paper

Volume reduction of hot cell plastic wastes

November 1989

The remote analytical laboratory (RAL) provides chemical analysis service for the Idaho Chemical Processing Plant, a facility that processes government-owned spent reactor fuel. Many of the samples analyzed in the RAL are radioactive and must be handled in a shielded, remotely operated hot cell. The design of the hot cell includes provision for removal of contaminated wastes generated by cell ... [Show full abstract] operation. Solid wastes are transferred out of the cell and into a sealed 60-{ell} polyethylene container. No commercially available or literature-described waste compactors were found that were suitable as a retrofit installation in the RAL hot cell. Efforts to develop a suitable compactor resulted in development of a 15- {times} 15-cm grid of heated Nichrome wires, 2.54 cm on center, used to cut the waste into small pieces. It is estimated that a projected operating rates, a saving of at least one waste container per week will be achieved with any combination of the volume-reduction techniques described. This represents a savings of

400 in the cost of the container alone. An ordinary steel drum used as a secondary container is an additional

60. If a remotely retrievable drum is required, the cost is $500. Significant savings will be achieved in the expense of transporting the waste container to the waste storage area and the considerable cost of preparing the storage space and future permanent disposal. All of the systems described can be easily repaired or replaced remotely.

Article

Multiple Osteoma of the Mastoid Cavity

June 1948 · Archives of Otolaryngology

W A MARROCCO

OSTEOMA of the mastoid process is infrequent;¹ multiple osteoma occurring within the mastoid cavity is rare.² REPORT OF A CASE H. B. a white man aged 39, was admitted to the hospital because of acute nasopharyngitis. On routine examination, a swelling was noticed behind the right ear in the mastoid area (fig. 1). It was not painful or tender to touch; in fact, the patient was not aware of its ... [Show full abstract] presence. The auricle was pushed slightly forward. Both external auditory canals were dry and clean. Both drums were intact and had a normal appearance. Hearing was not affected in either ear. There was no history of any infection of the ear or of "ear trouble."Roentgenograms showed a well developed normal pneumatic mastoid bone on the left side. On the right, there was a large "expanding lesion," the size of the entire mastoid process, containing six separate small osteomas (figs.

Article

Digital Fluid Logic Elements.

January 1963 · Advances in Computers

H. H. Glaettli

Within a relatively short period— that is, almost since the beginning of their existence, electronics and semiconductor technique have penetrated the field of control devices and computing elements thoroughly. One is, therefore, likely to believe that computing is only possible because of the existence of these more or less recent developments. This widespread belief, however, neglects the fact ... [Show full abstract] that purely mechanical devices were the forerunners of present day computers, and the historical sequence confirmed by pointing to our preference in using the expression “to mechanize” instead of “to electronize” can easily be found. “Forerunner” is not synonymous with obsolete; the contrary is true: mechanical elements have been in constant use up to now, and are an object of continuous research and development efforts. This is mainly because of their unique properties to be discussed in this chapter. It is interesting to see that until recently not too many thoughts were spent on hydraulic or pneumatic circuits. Recently, a new section was added to the catalog of mechanical elements: amplifiers using liquids or gases and containing neither moving nor deformable parts (except the fluid itself) were invented. A variety of amplifiers, storage devices, and switching elements now exist, of which not much is known. Many difficulties in understanding are because of the complexity of the hydrodynamic equations that describe the phenomena in question and because all three dimensions play an important role. The present situation in the field of digital fluid logic elements is discussed.

Article

Full-text available

Modeling of milled straw heap separation in air-flow classificator with two pneumatic ducts

May 2016 · Advanced Engineering Research

The research subject is a multivariate analysis of the air-flow classification process of the straw heap with a predetermined fractional composition supplied to the cleaning after the drum destroyer. The work objective is to identify patterns of the air separation using three pneumatic ducts with a linkage parameter variation. The investigative technique is an analytical modeling. The effect of ... [Show full abstract] probabilistic characteristics of the heterogenic thrashed heap supply, airflow velocity distribution by the separator width, and density function of heap components terminal velocity on the separation is evaluated. The air-flow classification process on each section of the pneumatic duct is considered. To this end, the mathematical expressions averaging the air classification indicators of the consistently functioning three pneumatic ducts and a stochastic quasistatic mathematical model of the separator operation with three pneumatic ducts in series are used. The results of the separator parametric synthesis and its technological parameters are presented. The fractional constituents of the heap components and their percent-sizes in each air-classified fraction are shown. The possibility of the air-flow classification of the crushed straw heap in the predetermined factions at the preset productivity of 0.6-0.7 kg/m∙s is revealed. It is found that under the rational functioning of the air separator, the straw content in the service faction is 97.03%. In this case, the minimum grain content is 0.03%, and mineral impurities are 0%. It is revealed that the air separator with three pneumatic ducts in series is sufficient for separating the crushed straw heap with the predetermined agro-technical requirements.

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FACE TECHNOLOGY IN GERMANY'S COALMINES IN 1985.

Abstract

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