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By Yumi Nakashima, Setsuo Maeda

Vibration magnitude and frequency of the z-axis vehicle seat are time-variant, which are influenced by not only vehicle vibration characteristics themselves but also road surfaces, speeds and the human body. There is little in the current reporting about evaluating and analyzing automobile seat vibration that focuses on the time-variant. Yaguchi et al.1 has proposed a method to evaluate automobile seat vibration that is based on judgments using a subjective mental state. Their method focuses on the time-variant magnitude of the peak frequency on a power spectrum density. However, their method has no consideration of all the frequency contents of the discomfort, nor comparison between different peak frequency vibrations. Suzuki2 has emphasized that the vehicle vibration should be judged by a series of vibration stimuli to evaluate, because the vehicle vibration is time-variant, which isn’t a matter of the relationship between a single vibration stimulus and a subjective response. He clarified that the human sensation to the vehicle vibration discomfort changes every moment showing the relationship between the frequency-weighted r.m.s. acceleration calculated every 5 seconds and the category judgment to vehicle vibration discomfort every 5 seconds. However, his study doesn’t show what parameter connects to the subjective final judgment to vehicle vibration. Therefore, we applied the method similar to ISO100563 considering the time-variant to the vehicle seat z-axis vibration evaluation. The new method for the vehicle seat vibration considering the time-variant was examined on the hypothesis that the final subjective evaluation must be conducted from the judgment summarizing a series of vibration stimuli. Methods The vibration bench system, which reproduces the movement of a vehicle floor, was used for the experiment with the single-axis (vertical direction) four-post road simulator system, which is usually used for a car, as shown in Fig.1. The experiment was done on the right side of the vibration bench using the floor vibration which was 5.5 minutes, 0.822 m/sec2 (Wk) over the range 0.5-20Hz with 4 male subjects (age ave21.5, SD0.5, weight ave75kg, SD7.91kg, height ave166.8cm, SD5.2cm) and 4 suspension seats. As Fig.2 shows, subjects evaluated the degree of discomfort every 5 seconds to each seat vibration measuring the seat z-axis vibration acceleration. [ ]

Jan 6, 2006

By Jasinder S. Jaspal

Most of the underground coal in the United States is mined via room-and-pillar mining methods with continuous miners. These machines operate intermittently because they have to wait for shuttle cars to interchange positions. To overcome this discontinuity in shuttle car haulage and to realize the full production potential of continuous miners, the U.S. Bureau of Mines developed a multiple-unit continuous haulage (MUCH) system through a research contract with Jeffrey Mining Machinery Div. (JMMD). The MUCH system consists of 12 rubber-tired vehicles and a bridge conveyor. The rubber-tired vehicles are connected by a unique mechanical linkage system to form a 250-ft train. The mechanical linkage permits the vehicles to track-retrack the preceding vehicle in both inby and outby directions. The cut coal cascades from one vehicle to another until it is discharged on the section conveyor belt. The MUCH system provides continuous haulage to the continuous miner. The MUCH system was initially surface tested by JMMD. Subsequent extensive testing was conducted by the Bureau at its test facilities at Bruceton, P A. Deficiencies found during testing were corrected. This report summarizes initial tests by JMMD and subsequent extensive tests and evaluation by the Bureau.

Jan 1, 1989

By W. D. Walker

The trend toward encouragement of worker participation in accident prevention in the coal mines of the United States is not new; however, it has been given added impetus in recent years and is now definitely progressing. It has been found by experience that, although there are many approaches to a mine-safety program that will include the workers themselves as well as their supervisors, no one way is suitable under all circumstances. It requires the concerted efforts of many agencies working along parallel lines toward a common goal. The following seven principal agencies, using somewhat different methods, are listed to illustrate how this problem is approached throughout the coal-mining industry 1. Federal Bureau of Mines. 2. State mining departments (in individual States where coal is produced). 3. Programs conducted by individual mine operators. 4. Programs conducted by mine workers' organizations (unions). 5. Institutes, societies, and other educational organizations. 6. Coal operators' associations (regional and national). 7. Universities, college, and high schools. Each of the seven approaches to safety are discussed briefly, and their methods end contributions, such as publications and other activities, are listed.

Jan 1, 1953

By S. T. Reese

STATISTICS of injuries in the quarrying and related industries in the United States first became available when the Bureau of Mines collected reports from the operating companies for the calendar year 1911. Since then reports have been collected annually. The present bulletin, covering the calendar year 1952, is the 33d publication containing statistical data on injuries at quarries and related plants, and it is the first to be published since 1944. The last publication was Bulletin 458, Quarry Accidents in the United States during the Calendar Year 1942. The unpublished statistics for 1942-51 may be found in the Appendix of this bulletin. The Bureau of Mines is authorized to collect data on injuries at quarries, but there is no Federal law that compels operators to supply such data, and the reports received from operators are voluntary responses to the Bureau's requests for information. Although the figures presented herein may not be complete for the entire industry, every effort has been exerted to make them so, and the figures given are believed to be thoroughly representative of the hazards to which quarry workers are exposed. Moreover, the figures are com¬parable as between States -which is significant in view of the lack of uniformity among the States as regards classes of plants covered by State laws, classes of injuries covered by State reports, and other factors that tend to make it impracticable or impossible to compare the injury experience of one State with that of another or to comprehend the relative importance of the various causes of injuries in the industry as a whole.

Jan 1, 1955

By Lyman C. Hitchcock

The objective of this program was to determine the minimum luminance requirements for underground coal mining work from the working face to the first transfer point. The resulting data encompasses 114 visual tasks from conventional continuous and longwall mining methods representing the salient visual tasks found in the jobs listed. Cutter Operator Roof Bolter Face Drill Operator Airdox Operator Longwall Jackman Shuttle Car Operator Loader Operator Shot Fireman Continuous Miner Operator Longwall Head Conveyor Operator Longwall Tail Conveyor Operator

Jan 1, 1973

By Eric S. Weiss, Deno M. Pappas, Timothy M. Barton

During the past few years, the Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) has been evaluating developments with surface support liners which includes shotcrete and thin spray-on liners (also referred to as sealants, coatings and membranes) from a ground control perspective. The proper selection and use of a surface support material can significantly enhance ground control which may result in a decrease in worker related injuries due to ground falls. The purpose of this paper is to evaluate the preliminary findings of a long-term underground study of various types of surface support liners, and to examine installation practices that are critical for an effective liner material application. The underground study utilizes NIOSH’s Lake Lynn Laboratory Experimental Mine to evaluate the long-term performance of several types of shotcrete and thin spray-on liner materials. Liner material performance to date was evaluated on a regular basis over a three year period. Although the study is still ongoing, critical mining practices were identified that may seriously affect the bond of the liner material to the mine roof and rib.

By John E. McCullough

The purpose of this development program is to design and develop a known volume air sampling pump for use in measuring the amount of radio-active material in the atmosphere of an underground uranium mine. The principle nuclear radiation hazard to underground uranium mines comes from the mine atmosphere. Daughter products of 222-radon, namely 214-polonium, 214-lead, 214-bismuth and 214-polonium, are inhaled by the miner, resulting in a relatively high lung cancer rate among these workers.

Jan 1, 1976

By Clarence A. Wright

The Missouri-Kansas-Oklahoma lead and zinc district, better known as the Joplin district, includes the mines in southwest Missouri and in those parts of Kansas and Oklahoma that are directly adjacent. (See PI. I.) This report of investigations carried on by the Bureau of Mines gives the methods used in mining and milling and indicates in some detail the conditions that affect the efficiency of those methods; it does not attempt to discuss the geology of the district, except incidentally, as this has been described in numerous reports by several geologists. Some of the more important recent publications are those of the United States Geological Survey by Smith and Siebenthal, a Bain, b and also those of the Missouri State geological survey by Buckley and Buehler." Other reports are those by Schmidt and Leonard," and Winslow,e of the Missouri geological survey, by Haworth and Crane,! of the Kansas geological survey, and by Jenney.g Although the lead and zinc ores are closely associated, the proportion of zinc ore mined at present is far greater than in former years. For this reason and because the losses in milling zinc ores are proportionately greater than in milling those of lead, the zinc ores are here given most consideration. Only the mines and mills actually examined and tested are discussed in detail, statements of results being restricted to the mines in general, with no special reference to anyone mine. Several mill tests were made to determine in a general way the efficiency of the milling practice in this district and to discover at what stage of the process the losses were greatest. Making these mill tests proved difficult,for, because of the arrangement of the mills and the necessity of estimating the tonnage treated, systematic mill testing and sampling can be done at only a few plants. Many tables giving results of mill tests and screen tests have been omitted because they would serve only to emphasize the important points shown by other data given. The writer has tried to bring out the possibilities of making certain improvements that would effect a greater saving, and has endeavored to avoid the use of technical terms and phrases in order that all statements may be clear and easily understood.

Jan 1, 1918

By George Markon

The importance of United States coal exports as a component of the national economy, the potential for growth of these exports, and the inter-national character of this sector of the coal industry are described in this report. The report summarizes some of the many background elements in the rise of United States coals to preeminence in highly competitive world markets. It presents some insight into this important sector of United States industry and the positive contribution of this sector to the Nation's balance of payments. It contains pertinent basic statistics on production, trade, and consumption of coal in most major markets for 1960-66. The report examines the movement of United States coals from mines to export markets, tracing and describing origins, exit ports, prices, and trends as well as inland and ocean freight rates and other data vital to an under-standing of some of the practices and complexities of the United States coal markets abroad. A brief sketch of coal production and consumption in principal importing countries is also presented with a short review of some of the more current practices and problems of these countries. Coal produced in inland areas of the. United States can be moved to and distributed economically within coal-producing countries overseas and in Canada. Quality coals from the United States can successfully compete with foreign coals in nearly any area of the world on a truly economic basis because of their high grade and their low cost which derives from the high productivity of the miner and from reasonable ocean freight rates. Because of tariffs, trade embargoes, quotas, and other restrictions, how-I ever, foreign coal markets are relatively limited. Further limitations are imposed in some countries by economic conditions which restrict all imports as a matter of financial and economic necessity. Despite these obstacles, United States coals have brought lower cost quality coals to a large segment of the foreign energy market.

Jan 1, 1968

By D. Harrington

Ventilation of underground workings consists of establishment of such control of air currents that the underground workers may work in safety, with maximum comfort and efficiency, mad without impairment of health; and that the mine openings may be made subject to such control of air flow as to remove from the workings at ordinary times harmful gases and dusts, and at time of emergency, such as fire or explosion, there may be maintained as much or as little air flow as may be desired covering portions of the mine or the mine in its entirety. Control of air flow is the keystone of any ventilating structure, and this very essential feature is obtainable only by the installation of mechanically operated fans, to ether with other ventilating devices such as doors, overcasts, regulators, etc. Every mine, large or shall, coal or metal, should from the outset be equipped with a fan. While much has been written about natural ventilation and many claims have been made that in specific mines there is sufficient natural al" flow, there are few if any mines, coal or metal, where natural ventilation supplies anything like adequately safe or healthful conditions for underground workers even at ordinary times; and at a time of mine fire or explosion the mines depending upon natural ventilation are practically helpless, and certainly are decidedly dangerous to those unfortunates forced to be in them.

Jan 1, 1933

By Ronald S. Conti

The Bureau of Mines conducted a comprehensive laboratory study of the thermal ignitability of various carbonaceous dust clouds with particular emphasis on various ranks of coal dust. The tests were conducted using a new 1.2-L furnace. Autoignition temperatures of dust clouds were obtained as a function of coal volatility and particle size. Dust particles and gas samples were collected by a rapid-sampling system in order to study the reactions involved in preignition and postignition processes. The autoignition temperatures measured in the new 1.2-L furnace were significantly lower and therefore more conservative than those measured previously in the Godbert-Greenwald furnace. The combined effects of thermal and electrical ignition of dust clouds were also studied in the 1.2-L furnace using electrical discharges of varying energies at ambient and elevated temperatures. The minimum spark energy necessary to ignite a dust cloud decreased significantly as the temperature of the dust cloud increased.

Jan 1, 1983

By C. W. DeLong, L. L. Farnham, L. A. Stewart

This paper is one of a series covering mineral resources of the Nation . It describes briefly most of the known manganese deposits of eastern Arizona , which for the purpose of this report includes the counties of Navajo , Apache , Gila, Graham, Greenlee , Pinal , Pima , Santa Cruz , and Cochise . With few exceptions , these descriptions are the result of field examinations by the writers . Work on this paper was begun in May 1956 , and in the following 18 months 151 deposits were examined . The distribution of the deposits by counties is as follows : 1 in Navajo , and 1 in Apache , 37 in Gila , 4 in Graham, 13 in Greenlee , 25 in Pinal , 13 in Pima , 12 in Santa Cruz , and 45 in Cochise . In surveyed areas the locations of the deposits are described by section , township , and range and in unsurveyed areas , by approximate projections of these subdivisions . The township and range numbers refer to the Gila and Salt River base and meridian . The history, production, ownership , geologic setting , and mining methods used are discussed for most of the deposits that were visited . Probably , some occurrences have been overlooked , but all of the principal ones have been examined . Ore dressing studies were made of typical ores from several of the larger districts . The work was performed in the laboratory of the Bureau of Mines Tucson Metallurgy Research Laboratory . The results of these studies are given with the descriptions of the deposits from which the samples were taken .

Jan 1, 1961

By Sheridan J. Rodgers

Toxic fumes generated during shot firing under actual mining conditions were measured. Eight shots with Gelodyn-2X and seven shots with Tovex-100 4VT were monitored. Average CO values for Gelodyn-2X and Tovex-100 4VT were 0.20 ft3/lb and 0.09 ft3/lb, respectively. Average N0x values for Gelodyn-2X and Tovex-100 4VT were 0.049 ft3/lb and 0.026 ft3/lb, respectively. The results obtained with these in-mine tests will be used by the U.S. Bureau of Mines in the development of a large chamber method of measuring fumes from shotfiring of explosives.

Jan 1, 1977

By D. R. Babich, E. R. Bauer

Noise-induced hearing loss (NIHL) in mine workers, especially underground coal miners, continues to be a problem in the mining industry. The recently enacted MSHA noise standard, Part 62 – Occupational Noise Exposure (Federal Register, 1999), is aimed at reducing NIHL in the mining industry. The U.S. National Institute for Occupational Safety and Health (NIOSH) is conducting a cross-sectional survey of noise sources and worker noise exposures to address NIHL in various aspects of coal mining including surface mining, coal preparation plants and underground mining. In underground bituminous coal mining, noise surveys, consisting of full-shift worker noise exposure, time-motion studies and equipment noise profiling, have been completed on longwall and continuous miner sections in six underground coal mines. The studies revealed widely varying shift-to-shift worker exposures, with workers in certain occupations routinely exposed to potentially hazardous levels of noise. A summary of these studies is reported, including worker dose, source/dose relationships and equipment noise profiles.

By L. C. IlsLey

"During the last eight years there has been a noticeable increase in the use of permissible equipment in gassy and dusty coal mines. This trend has undoubtedly been toward greater safety in mining, but in spite of this all is not well ""along the front.""In many mines those in charge, either through ignorance or supposed economy, have neglected to install sufficient copper and maintain good bonding on the rails used for return circuits to have a safe working voltage for the permissible equipment which is intended to afford them safety.Low voltage, when properly analyzed, is not economy but frequently is an expensive oversight. Burned-out armatures, controllers, rheostats, and switches are costly in themselves to repair or replace, but the greatest cost in many instances is the loss of production resulting from idle and broken-down equipment.From a safety standpoint, excessive low voltage where permissible equipment is necessary is almost criminal negligence. A burn-out of any kind is liable to cause an arc that may burn its way through a casing wall and bring about a hazardous condition if gas or dust in explosive proportions should be present. Again, all wiring, both interior and exterior to the apparatus, is subject to the extra heating consequent upon low voltage. It should be remembered that if the voltage drops the current must increase a corresponding amount in order that the same work may be accomplished; and as the heating effect is as the square of the current, an enormous overheating of the electrical parts and wiring often takes place. This heating effect is especially detrimental to trailing cables used on portable equipment, because under the most favorable conditions the size of cable selected is only barely sufficient to do its work properly at a safe working temperature; therefore, when the extra current load is added because of poor voltage, overheating is sure to result, with consequent deterioration of the insulation, This effect greatly increases the liability of cable failures in service, and in turn adds to the hazards incident to the use of portable equipment of the permissible type involving the use of trailing cables.Some manufacturers have tried -to protect their equipment from low voltage, especially below a certain point, by -installing low-voltage relays which will trip when the voltage falls to a predetermined value. It is understood that some operators have hesitated or refused to install such low-voltage protection because they were aware that the voltage conditions were so poor that the equipment could not operate under the safe limits set. It is difficult to understand how any progressive company that is willing to go to the ex-pense of installing permissible equipment could be so shortsighted in this phase of common sense, safety, and economy."

Dec 1, 1929

By H. M. Thorne

The oil-shale deposits of the Puertollano basin in the Spanish province of Ciudad Real appear to have been give little consideration in discussions of oil-shale resources throughout the world. A small, integrated oil-shale operation has been conducted at Puertollano since about 1922 by a French company, Sociedad Mimora y Metalurgica de Penarroya, hereinafter referred to as "Penarroya", but only within recent years have the potentialities of the Spanish oil-shale deposits been recognized. Empresa Nacional "Calvo Sotelo" do Combustibles y Lubricantes, hereinafter designated as "Calvo Sotelo," which was created in 1942 by the National Industrial Institute of Spain to produce liquid fuels from oil shales, has made marked progress in the design and construction of a complete oil-shale plant at Puertollano. Penarroya is mainly a coal-mining company, and the oil-shale operations were on a small scale of approximately 220 tons a day in October 1947. It is an integrated operation comprising oil-shale mining and retorting and shale-oil refining. Motor gasoline, Diesel fuel oil, light burner fuel oil, lubricants, paraffin wax, cresols, and ammonium sulfate are manufactured.

Jan 1, 1950

By R. K. Zipf

A method is presented for creating realistic numerical models for practical coal mine ground control. The method includes procedures to collect the necessary mechanical input parameters from a geologic core log, procedures to set up a model and procedures to interpret calculation results. The input parameters come from a detailed geologic core log and extensive point load tests of estimate rock layer strength. A suite of material property input parameters is proposed which allow the user to go from core log to numerical model inputs. Rock bolt anchorage properties are also linked to the material properties of each geologic layer in the model. Following this procedure leads to very realistic calculations of the rock failure process and rock support system behavior. These calculations in turn enable realistic comparison of the effectiveness of alternative rock support systems.

By Bernard Lewis

The ignition problem: for a layer of firedamp bordering on a cloud of detonation products is evidently considerably more complicated than in the usual laboratory ignition experiments, in which a well-defined volume of gas is heated and the occurrence of ignition is observed after an induction period. An atmosphere of firedamp exposed to the detonation of a high explosive is subjected to heating by shock-wave compression and thermal conduction and to intermixing at the interface of the firedamp atmosphere and the cloud of deto¬nation products. Although a reliable physical-chemical analysis of the problem is not yet possible, one may nevertheless form a general view of the role of compression waves and the processes of heat transfer and diffusion at the interface. Near the mouth of a shot hole, or near a freely suspended cartridge, the firedamp atmosphere attains very high temperatures by adiabatic compression, and it is certain that such temperatures are sufficient to initiate chemical reaction. The pressure wave pattern is reproducible from one test charge to another if the initial experimental conditions are held constant; on the other hand, experiments on firedamp ignition do not yield a reproducible threshold condition for ignition, but only an ignition probability. Thus, the induction periods are sufficiently long that there is time for the compressed', heated gas layers to undergo random changes that may quench or promote ignition. Therefore, the analysis of the ignition problem hinges primarily on the discovery of the random events that modify the chemical reaction in the activated gas layers.

Jan 1, 1948

By P. S. Haury

"INTRODUCTION Preliminary examinations of the Mohawk zinc prospect were made by John 14. Price and the author in July, August, and September 1943. Considerable quantities of oxidized lead and zinc minerals were found in old shallow work¬ings along two faults - one an over thrust fault with Paleozoic limestone in the hanging wall overlying Cretaceous shale and arkose in the footwall of the fault, and the other a bedding fault in the Paleozoic limestone.The chances appeared good for finding important lead-zinc sulfide ore bodies at 200 to 300 feet beneath the surface, so exploration in three steps by the Bureau was recommended:Surveying, mapping, and character sampling of the outcrops with topographic and geologic mapping of the immediately surrounding area.Preliminary drilling of four test holes, aggregating about 1,500 feet, to locate the top of a possible sulfide ore zone and determine the thickness and intensity of the sulfide mineralization.Contingent upon favorable results of the second step, diamond drilling of about 6,300 feet of additional hole to explore the sulfide ore bodies.The outcrops were surveyed and sampled, a topographic map was made of the area, and the geology was mapped. A project was set up for preliminary drilling of step 2 in the fiscal year 1944-45. An access road to the drill sites was built in April 1945. Diamond drilling was started on April 28 and completed on September 25, 1945, under the supervision or the Bureau of Mines. The exploratory work is covered in this report."

Oct 1, 1946

By Wilbur I. Duvall, S. L. Windes, Leonard Obert

"Previous investigations, too numerous to be listed in entirety, have been performed to determine the physical properties of rock. When considered according to their objectives, most of these investigations can be grouped as follows: First, the geologic group (1,2),4/ in which the purpose was to obtain information on the physical properties of the rocks that make up the earth's crust. Particular emphasis has been placed on the determination of the elastic constants--that is, Young's modulus, the modules of rigidity, and Poisson's ratio – as these quantities determine the propagation characteristics of seismic waves. Second, the structural properties group (3 - 11), in which the physical properties of architectural or monumental stone, concrete and aggregate rock, road blocks (cobblestone), and the like were desired. The tests have been quite general and include, besides the elastic properties; the compressive and tensile strength, and the toughness, hardness, and weathering properties of many types of rocks.To .a lesser degree, investigations have been carried out to determine the physical properties of mine rock. A few reports (12 - 14) present data on the crushability and grindability of mine rock, and a large number of papers discuss grinding and crushing procedures and methods of analyzing the data (for example, see references 15 - 17). Some of the latter group also have given the results of tests on mine rock; however, comparatively few include an adequate petrographic description or information on other physical properties of the rock. A few papers,(18 - 22) have reported studies of the strength of rock specimens in respect to the strength of parts of mine structures, such as pillars, roof, arches, etc. Other papers (23 - 26) have discussed investigations on such subjects as primary and secondary crushing, diamond and pneumatic rock drilling, explosive breaking and shattering of rock, rate of drifting and miring, and other allied problems. The majority of these reports have given no more than a cursory, description of the rocks and have included no statement regarding the physical properties. When statements have been given regarding the physical properties, they have usually referred only to isolated tests, making correlations between variations in the physical properties and variations in the .test under consideration difficult, if not impossible. Some reports have included handbook values on such characteristics as the crushing strength, hardness, and toughness. This practice is not satisfactory, because these values are usually given for col¬lective types of rocks, such as granites, limestones, and marbles, and it is known that the variations of the physical properties within these groups is often larger than the differences between the groups."

Aug 1, 1946