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By B. W. Cavender

Innovative mining and metallurgical operating techniques or processes can be identified and developed by systematically analyzing change as it occurs within the mine, plant, technology, or industry. Sources of change to be monitored for innovative opportunities include unexpected successes or failures, incongruities between perceived and actual events, process needs, changes in perceptions, and the development of new knowledge. Innovation can be effectively organized, practiced, and managed. The perception of change as an opportunity rather than a threat is mandatory, as is the systematic measurement of innovative performance. Innovation is enhanced by specifically-designed policies regarding organizational structure and staffing, daily management practices, and compensation and incentives.

Jan 1, 1994

By Carlos White

El presente texto describe la importancia del correcto funcionamiento de los equipos en las faenas mineras a través de las pautas de inspección y formularios impresos en papel y llenados manualmente. Sin embargo, estos escritos son de difícil interpretación -en tanto dificultan su digitación a los sistemas corporativos computacionales de mantenimiento, reparaciones y compras. Por ello, se implementa un sistema de gestión integral de activos para faenas industriales que utiliza identificación por frecuencia (RFID). Así, el primer paso es identificar cada componente y equipo a través de un transpoder FID que permite su identificación inequívoca y automática. Una vez definido el componente, el sistema permite gestionar desde una interface intuitiva y de acceso controlado por perfil de usuario, las tareas de determinar, monitorear y controlar a lo largo de su vida útil y en toda la cadena de abastecimiento.

Jun 1, 2016

By L. B. Berger, W. P. Yant, R. R. Sayers

"At the request of the Chesapeake & Ohio Railroad Co. a number of tests were made to determine the temperature, humidity, and composition of the atmosphere in certain tunnels of that railroad between Clifton Forge, Va., and Hinton, W. Va. The purpose of these tests was to determine conditions in the cabs of freight locomotives while pulling trains through these tunnels. Tests were made of two types of locomotives, classified by the railroad company as the H-6 and H-7. Both are of the Mallet type, but the H-6 class has one pair of cylinders operating at boiler pressure and the other pair compound, whereas the H-7 operates all four cylinders at boiler pressure, thereby exhausting steam at a higher temperature than the H-6. It was desired to determine the relation between conditions on the H-6 and H-7 engines under comparable conditions of operation. This information supplements previous tests by the Bureau of Mines, discussed in its Reports of Investigations Serial No. 2624, entitled, ""Temperatures in Cabs of Freight Locomotives Passing Through Tunnels of Chesapeake & Ohio Railroad, 11 by s. H. Katz and E. G. Meiter, July, 1924. Three incidental tests of passenger engines were also made."

Feb 1, 1928

By George A. Savanick

Borehole (slurry) mining, in which a tool incorporating a water-jet cutter and a downhole slurry pump mines phosphate through a borehole, was field tested in northeastern Florida as part of a Bureau of Mines program to increase the domestic availability of critical minerals. Approximately 1700 tons (1.54x106 kg) of phosphate ore were mined at 40 tph (10.1 kg/s) from a depth of 250 ft (76 m). The borehole was filled with water during mining for roof support and to assist slurry pumping. Underwater cutting was enhanced with an air-shrouded water jet. Mined cavities were backfilled to prevent subsidence after abandonment. Roof subsidence during mining was avoided only when the cavity was filled with water. Environmental monitoring before, during, and after mining included hydrological studies and measurements of water quality. Significant water quality changes occurred only in the zone being mined and were confined to the immediate area of the borehole.

Jan 1, 1983

By A. G. Loomis

METHODS for measuring relative permeability as a valid function of saturation were compared by the. Bureau of Mines, using core samples from representative oil-productive California formations, from the Bartlesville sand in Oklahoma, and from synthetic samples. Measurements for gas-oil systems were made by steady-state dynamic, unsteady-state displacement and two stationary-phase methods. Measurements for water-oil systems were made by the unsteady-state displacement method. As the ratio rather than individual relative permeabilities is measured by the last method, three methods for calculating individual relative permeabilites from their measured ratio were compared for gas-oil systems and two methods for water-oil systems. Errors arising from capillary discontinuities, such as the end effect and stabilized-zone flow, are discussed and evaluated; possible errors rocs arising from turbulant flow are also examined. The inapplicability of non-steady-state methods for water-oil systems that are not definitely oil-wet is discussed in detail. Measurements of relative permeability to both gas and oil can be made quickly and accurately by the steady-state dynamic method when rates of flow of the two phases are sufficient to minimize the capillary discontinuity at the outflow end of the sample. At such rates relative permeability-saturation measurements are essentially independent of the rate of flow. The steady-state method wits modified by a dispersion section at the inflow end of the sample acid designated tie dispersed-feed method.

Jan 1, 1962

By R. D. Barer, M. B. Bever

Age hardening alloys are quenched from the solution treatment to room temperature in order to retain a supersaturated solid solution. Some alloys age "naturally" in this condition but in most alloys aging is induced "artificially" by heating to intermediate temperatures. Cold working of the supersaturated solid solution accelerates the aging process and quenching strains have the same effect. The investigation reported here is a study of the progress of aging in specimens quenched directly from the solution treatment to various aging temperatures. This procedure reduces the temperature interval of quenching and the resulting quenching stresses. It also eliminates any changes which would take place in the undercooled sample at room temperature prior to aging at an elevated temperature. Isothermal aging is thus approached and its kinetics may be studied. An aluminum-copper and an aluminum-silicon alloy were chosen for this investigation. The aging mechanism of aluminum-copper alloys is complex while the aging of aluminum-silicon alloys is nearly ideal. As standards of comparison for the samples directly quenched to the aging temperature, specimens were also age hardened by the usual procedure in which solution treated samples are first quenched to room temperature and then reheated to the aging temperature. Review of Previous Work The mechanism of age hardening has been the subject of a controversy which has ranged from the theory of outright precipitation of an equilibrium phase to theories based on subtle changes occurring in the matrix prior to precipitation. A detailed critical review of the literature up to 1939 is available1 and contributions to the general theory of age hardening continue to be made.2,3 Age hardening, whatever its mechanism, involves the nucleation of a second phase within a supersaturated solid solution. Theoretical considerations4,5 indicate that the rate of nucleation reaches a maximum at an intermediate temperature below the temperature at which supersaturation sets in. Studies of precipitation at various subcritical temperatures have demonstrated that the largest property changes in a given time occur at such intermediate temperatures.6,7,8 The precipitation of a phase from supersaturated solid solution is accelerated by strains which may result from quenching or cold work. Phillips and Brick9 established that quenching strains are an essential condition for the age hardening of aluminum-copper alloys at room temperature, at least for aging periods of less than 30 days. They also found that on aging at 300°C the hardness increased faster and reached a higher maximum after quenching into water than after quenching directly to the aging temperatures. Fink and Smith10 observed preferential precipitation on slip bands and grain boundaries in aluminum-

Jan 1, 1950

By Emil B. Milosavljevic

Problems associated with distillation and other classical methods for analyzing operationally defined cyanide (CATC, WAD, Total and Free Cyanide) will be discussed. These methods often achieve incomplete, species dependent cyanide recoveries and suffer from serious interferences. Depending on the relative concentrations of interferents and other matrix constituents, underestimation (ultimately Type II errors probability of not detecting a constituent when it is actually present) or overestimation (ultimately Type I errors -probability of deciding a constituent is present when it is actually absent) of the cyanide levels present in a ,given sample may occur, causing in the first case false security and in the second case, excessive cyanide treatment costs. Mahy, if not all, enumerated problems can be solved by using novel flow injection (FI) gas-diffusion amperometric methods. A modification of the recently approved FI ligand exchange (FIILE) method for determination of available cyanide (USEPA Method OIA-'l677) that obviates sulfide interference will be discussed. Eight laboratory round-robin data obtained for the FI UV -digestion (FIIUV) method that determines total cyanide (Proposed Method OIA-1678) will also be presented. In addition, some methods for cyanide speciation will be presented. Finally, research needed for developing reliable methods for determination of operationally defined cyanide in solid samples will be summarized.

Jan 1, 1998

By Maria I. De Rosa

Coal mine fires pose a constant danger to the safety of miners and to their livelihood. Underground mine fires pose an added hazard because of the confined environment with remote exits. Enactment of safety regulations [30 CFR2 75 and 771 for under- ground coal mines and surface coal operations has greatly improved the safety of miners. However, mine fires and fire injuries remain serious hazards for all coal mining operations. This report analyzes mine fires and fire injuries for all U.S. coal mining categories (underground coal mines, surface of underground coal mines, surface coal mines, and coal preparation plants) during 1990-1999. Fires involving contractors are also included in the analysis. Similar analyses (for underground coal mines only) by the former U.S. Bureau of Mines (USBM) were reported by McDonald and Pornroy [I9801 and Pornroy and Carigiet [I9951 for 1950-1977 and 1978-1992, respectively. For comparison purposes, data for 1978-1 992 are mentioned in the "Underground Coal Mine Fires" section of this report. Detailed analyses of mobile equipment fires for all underground and surface coal and metal/nonmetal mining categories during 1990-1999 have recently been reported by NIOSH [De Rosa 20041. Risk rate values (fire and injury risk rates) for the 10-year period (1990-1999) and for five successive 2-year periods within the 10-year period are derived. Risk rate values for individual states for the 10-year period are also derived. Other variables by state and time period include employees&apos; working hours, lost workdays, and coal production (underground and surface coal mines only). The number of fire fatalities is reported by time period. Variables such as ignition source, method of detection and suppression, equipment involved, location, and burning material are reported by five 2-year periods only. Furthermore, the number of fire injuries per number of fires causing injuries and total fires has been analyzed by year, ignition source, equipment involved, and location. For comparison purposes, the major fire and fire injury findings for all coal mining categories have been reported. The data in this report were derived from "Injury Experience in Coal Mining" [MSHA 1991a, 1992,1993,1994a, 1995a, 1996, 1997, 1998b, 1999c, 20001, "Fire Accident Reports" [MSHA 199 1 b,c; 1994b; 1995b,c; 1998a,c,d,e,f; 1999a,b,d,e], MSHA "Fire Accident Abstracts" internal publications, and verbal communications with mine personnel. Mining companies are required by 30 CFR 50 to report to MSHA all fires that result in injuries and fires that are not extinguished within 30 min of discovery. A small number of fires lasting <30 min without injuries reported in the "Fire Accident Abstracts" have been included in this report. The analysis in this report will provide the National Institute for Occupational Safety and Health (NIOSH), the Mine Safety and Health Administration (MSHA), and the mining industry with a better understanding of the causes and hazards of mine fires and fire injuries. It will also form a basis for developing future fire research programs.

Jan 1, 2004

FEBRUARY GENERAL MEETING The January General Meeting of the Institute was held in Kelvin House, Johannesburg on 21st January, 1970, at 4.30 p.m. Mr V. C. Robinson (Vice-President) was in the Chair. There were also present eighteen Members, Messrs M. Barcza, A. R. C. Fowler, R. C. J. Goode, Prof J. de V. Lambrechts, Messrs T. C. A. Meyer, J. A. Nixon, V. C. Robinson and P. W. J. van Rensburg (Council Members), C. A. Border, D. F. H. Grave, S. D. Hill, A. F. Lee, W. L. le Roux, C. S. Macphail, D. L Starkey, S. G. Taussig, W. T. L Wayman and Dr A. Whillier. Three Associate Members, Dr M. I. Brittan, Messrs R. Hemp and M. J. Martinson. One Student, Mr R. P. W. Henrard. Two Visitors, Dr N. G. W. Cook and Mr J. B. Smith. Secretary, Mr D. C. Visser. Total present: Twenty-six. 1. OBITUARY The Vice-President: "It is my sad duty to announce the death of the following members of the Institute: Reginald Gordon McConnell, Member, who joined the Institute on 24th April, 1946 and passed away on 26th September, 1969. James Henry Moore, Member, who joined the Institute on 28th February, 1951 and passed away on 2nd January, 1970. As a mark of respect to the memory of the deceased and in sympathy with the bereaved I would ask those present to stand and observe a few moments silence." 2. MINUTES The Vice-President: "May we confirm the Minutes of the General Meetings held on 15th October and 19th November, 1969, as published in the December, 1969 issue of the Journal?" 3. MEMBERSHIP The Vice-President: "I have pleasure in announcing that the names of the under-mentioned candidates, having been published in accordance with By-Law 5.2.2, Council has elected them to membership of the Institute in the following grades: Member: Woodford Anson Gilbert. Associate Members: Michael John Harvey Tonking, Schalk Willem Vorster, Edward Alfred Cole, Johannes Godlieb Bosch. Graduate: Leonard Raymond Kilpatrick. Affiliates: Clive Frere Knight Pouiton, David Philip Ayliff, Kenneth Gillings, Edward Gilbert East. Students: Stirling Graham Low, Petrus Stephanus van der Merwe, Louis Johannes Fourie, Clive Maxwell Winterstein. MEMBERS TRANSFERRED TO A HIGHER GRADE From Associate Member to Member: Albert Arthur Hazell, Neville Martin Hayne. "I welcome the newly elected members to the Institute and congratulate the members who had been transferred to a higher grade. 4. GENERAL BUSINESS The Vice-President: "I wish to announce that except for the student prizes awarded at the November meeting, Council has decided to make no awards for 1969. Are there any further matters to raise under the heading of General? If not, we will proceed to the next item on the agenda which is the presentation of tonight&apos;s paper. 5. PAPER FOR PRESENTATION The Vice-President: "Professor Starfield may I call on you to deliver the paper entitled "A rapid method of calculating temperature increases along mine airways". After the presentation of the paper, the Vice-President said: The Vice-President: "Thank you very much, Professor Starfield. Gentlemen, I think that many of you here, who have to do with the design of mines in an age where costs and difficulties generally, are increasing at a rate which we find almost impossible to keep up with, I would agree with you that we are fortunate to have a band of people like Professor Starfield, and others who are dedicated to producing the tools, and methods which we need to sort out these problems. I am sure that you would agree with me, that the old rule-of-thumb methods are finished forever, that we can never go back to the methods which served us in the past, when we were close to the surface and had not met the conditions which we are meeting now, and which we are going to meet in an increasing degree in the future. It is to people like Professor Starfield, with these clear, completely logically described new methods, that we look for the solution of our problems in the future. I think the whole problem of layout of any mine, is one where you can reliably prognosticate what you are likely to find in a variety of circumstances to meet the wide range of things which must happen when you consider the costs in these modern operations. Thank you very much, Professor Starfield, for coming and giving us this paper. Thank you for making plain to me how these mathematical models of yours are used. I am sure that what you have said will be a very valuable addition to the archives of this Institution. Thank you very much, indeed, and Gentlemen, will you please show your appreciation in the normal way." (Applause). Professor J. de V. Lambrechts, Mr R. Hemp and Dr A. Whillier then contributed to the discussion. (These contributions will appear in a later issue of the Journal.) PAPERS OPEN FOR DISCUSSION The Vice-President: "Listed on the agenda are papers open for discussion. I would suggest that anyone wishing to contribute to these papers submit their contributions to the Secretary in writing." CONCLUSION The Vice-President: "I wish to thank members and visitors for their attendance, and now declare the meeting closed." The meeting closed at 5.30 p.m

By S A. Steyn, I P. Douglas

Duvha Opencast is a large South African dragline operation supplying coal to the Duvha Power Station which is operated by Eskom, the state power utility. For Duvha to remain competitive with other collieries, it has proved necessary to continuously examine and investigate methods of reducing costs. With explosives representing a major portion of the total working costs, blasting is an obvious area of investigation.

Jan 1, 1991

By Wilhelm Wendt

About five years ago we showed that it is possible to use the spectral in- formation in the light emitted by the off-gas flame of a PS converter for on-line production control. Very recently measurements have been performed using improved optical equipment and data evaluation software, resulting in both improved accuracy and the establishment of new optical process parameters. Using the optical signals the slag heats could be stopped at a predetermined Cu content of the white metal with an accuracy of +0.2% Cu m the range 74-78% Cu. A good correlation was found between the slag composition and optical data, providing a possibility for on-line monitoring of the SiO2 content of the slag. The measurements indicate the possibility of predicting the optimum end-point of the copper-making stage and having real time information on the impurity removal. Factors influencing the optical parameters, such as blowrate, Pb content, temperature etc. will be discussed.

Jan 1, 1993

By Henry G. Granger

DURING upwards of three thonsand miles of canoc-travel in South America, including several mishaps, the writer has unfortunately lost his book of notes taken during the year 1894 in Dutch Guyana, or Surinam. But a year spent in a foreign country, visiting its principal mining properties, is necessarily productive of indelible memories and impressions, and some of these may be of interest to the Institute. The Guyanas include British, or Demerara, Dutch, or Surinam, French, or Cayenne, and the Disputed Territory, or that portion of Brazil on the northeast coast of South America. After passing the picturesque mountainous coasts of Colombia and Venezuela, one reaches a low, flat mud-bank which extends far out into the sea, so that from the steamer, over a couple of leagues of turbid, shallow water, one call just see the dismal outline of the pestilential "bush" that fronts the Caribbean sea, clear around to the mouth of the Amazon. Here, iii the order mentioned above, are the Guyanas. So much has been said about this out-of-the-way section during the late excitement over the Venezuela boundary question, that the historical part of the subject may be advantageously condensed. Gold-mining in the Guyanas is altogether placer-mining, and is of the same general nature throughout; hence by describing the methods in use in Surinam and the results there achieved, ail idea will be given of the work throughout the field. The product of this section is about three to four millions of dollars annually, mostly from Demerara, not because of superior richness of its placers, but as a result of its very much larger population, which exceeds twice the aggregate census returns of both Surinam and Cayenne. Mining ill all this section is of comparatively recent date, and is indirectly due to the decline of the sugar-industry. After the introduction of beet-sugar scores

Jan 1, 1897

By Rex L. Outzen

Houston International Minerals Borealis Project is an open pit heap leach operation. The operation uses open pit mining, two stage crushing, agglomeration, heap leaching, zinc precipitation and induction refining to produce approximately 50,000 ounces of gold per year. Due to the ore being extremely ameanable to heap leach processing techniques, low manpower requirements and efficient management, the operation is one of the lowest cost gold producing operations in the United States.

Jan 1, 1984

By M. H. Pelkki, R. J. Sweigard, P. W. Conrad, J. M. Ringe, D. H. Graves

Research has shown that excessive soil compaction is detrimental to the establishment of trees in reclaimed soils. Dry bulk density and penetration resistance are two soil parameters that can be used to indicate the level of compaction in reclaimed soils. It is believed that reclamation practices that minimize soil compaction will produce better results when forestland is the intended postmining use. The University of Kentucky has developed reforestation test cells on reclaimed soils at a surface mine in eastern Kentucky to test this hypothesis. Each test cell has been planted with various species of trees. Since 1997, data have been collected at these test cells for soil average dry bulk density, average penetration resistance, average depth to refusal and average survival rate of trees. These data have been correlated to determine the relationship between soil compaction and tree-survival rate. It is believed that these two soil-compaction parameters may ultimately be used to predict tree-survival rates on reclaimed surface mined lands.

Jan 1, 2003

By Ramie H. Thompson

1.1 BACKGROUND In many underground coal mining operations the use of electromagnetic field equipment, particularly communication systems, not only increases the overall efficiency of the mining operation but can be directly linked with mine safety considerations. The use of electromagnetic field producing equipment in underground coal mining operations can only be expected to grow. Several new communication systems have already been proposed. In addition, high-frequency producing equipments for many diverse uses in mining operations are under study. The use of these equipment in underground mining operations is hampered by the possibility of their electromagnetic fields interacting with the electric blasting cap operations commonly carried out in the mines. Such interactions can have at least two results bearing directly on mine safety: o premature initiation of the cap, either in its normal shot location or during hookup or transportation; o dudding of the cap so that normal firing operations do not cause irritation; thereby leaving unexploded high explosives after normal firing. Since the consequences of a premature initiation could, particularly in coal mines operations, result in catastrophe involving human life, the overall approach to prediction of possible hazard must be, as far as possible, of a "worst case" nature. The general problem of predicting possible RF hazards for any electroexplosive device (EED) is best treated by reference to Appendix A of

Jan 9, 1983

INTRODUCTION The geology of porphyry copper deposits in the southern Cordilleran orogen is the subject of this chapter. The area considered extends northwest from southern Mexico to the Columbia volcanic plateau, the Cascade volcanic province, and the Idaho batholith. Transversely it is a belt some 800 km (500 miles) in width bounded on the west by the Sierra Nevada range. Included within this area are many large segments considered unfavorable for hosting porphyry copper deposits, which are mentioned in the text. The region and its porphyry copper deposits have probably been more intensely studied and reported in the literature than any other area in the world. This summary considers regional geologic controls that governed formation of porphyry copper deposits within this province. Geologic factors that influenced the mineralogy and metallogeny of the deposits are also examined. Discussions with H. R. Cornwall have greatly helped in writing this section. GEOLOGIC SETTING The geologic setting has been summarized by Anderson (1966), Burchfiel and Davis (1972), Rogers, et al. (1974), and Lowell (1974). No porphyry copper deposits in this area are known to be pre-Triassic, so Mesozoic and Tertiary events will be stressed. Figs. 40 and 41 show basic data believed most pertinent to the topic of porphyry copper deposits. Pre-Middle Jurassic: Figs. 40 and 41 contain the principal structural and crustal ele¬ments found in the Cordilleran orogen after Anderson (1966), Schmitt (1966), Coney (1972), Rogers, et al. (1974), and Lowell (1974, 1976), together with location of some of the more important porphyry copper deposits. The western limit of the Precambrian craton is shown in Fig. 40 (Rogers, et al., 1974). East of that limit the crustal environment through which the porphyry copper plutons ascended includes the Precambrian basement as well as varying thicknesses of Paleozoic shelf and platform accumulations. The northwestern and western portion of the southern Cordilleran orogen west of the Rogers, et al. (1974) limit of Precambrian basement has what Churkin (1974) calls a thin continental crust. Brooks (1976) and Churkin (1974) describe oceanic volcanic

Jan 1, 1978

By Carl Altstetter, Emmanuel deLamotte

The influence of an external stress and plastic deformation on the allotropic transformation of single crystals of a Co-30.5 pct Ni alloy was investigated. Experimental results were obtained from dilatometry, X-ray diffraction, and optical and electron microscopy. The effects of stresses could be conveniently divided into three stress ranges. In range I, from 0 to about 400 g per sq mm, the specimens exhibited a multi-variant phase change on cooling and a considerable amount of retained cubic phase. In range II, from 400 g per sq mm to the elastic limit, hexagonal regions of a given orientation grew in size and the cubic phase disappeared with increasing stress level. In range III, just above the elastic limit, specimens transformed into hexagonal single crystals. It was found that plastic deformation, not applied stress, was the factor which determined whether a single-crystal product was formed. The observed macroscopic shear directions were mainly (112) on cooling, but the behavior was more complicated on heating under stress. To explain these properties of the phase change, a model based on the nucleation of partial dislocations is proposed. IT is well-known1 that, on heating, hcp cobalt transforms into an fcc arrangement by shearing on close-packed planes. The crystallographic orientation relationship of the phases is as follows: the habit plane is (OOO1)hcp ?{lll}fcc and a (1010)hcp direction is parallel to a (112)fcc direction. The temperature at which the transformation occurs in pure cobalt is around 420.C 1,2This temperature decreases with increasing nickel concentration: and at about 30 pct Ni it reaches room temperature. However, many of the transformation characteristics remain essentially the same, particularly the crystallographic features.495 A convenient way of studying the transformation is to alloy cobalt with nickel, thus avoiding the difficulties of doing experiments at the high temperatures needed to transform pure cobalt. Due to the hysteresis of the transformation it is possible to choose a Co-Ni alloy with an Ms temperature below room temperature and an A, temperature above room temperature. Either structure of such an alloy could then be studied at room temperature, depending on whether it had just been heated or cooled to room temperature. The choice of nickel is further favored by the small difference in lattice parameters between cubic cobalt and nickel and the similarity of their physical, chemical, and electronic properties. Co-Ni alloys are reported to have neither long- nor short-range order.6 The main purpose of this work was to investigate the influence of an external stress on the transformation characteristics of Co-Ni single crystals. It may be expected that slip, twinning, and transformation should have many features in common in cobalt, because the (111) planes of the cubic phase operate as slip planes when plastic deformation by slip occurs, they are the twinning planes, and they are the habit planes for the transformation. Many previous investigators7-&apos;6 have concluded that dislocations must play an important role in the nucleation and propagation of the transformation, just as they do for slip and twinning propagation. An external stress will affect their motion, and a study of its influence should yield further information about the atomic mechanism of transformation. The present work extends that of Gaunt and christian17 and Nelson and Altstette18 in both qualitative and quantitative effects of stress. The basic concept underlying all the present theories of the transformation of cobalt and Co-Ni alloys is the motion of a/6<112> partial dislocations over {1ll} planes of the cubic lattice. The ABCABC... stacking of the close-packed planes of the cubic phase can be changed into the hexagonal ABABAB... stacking by the sweeping of an a/6 <112> partial on every second plane. Twinning, on the other hand, requires a shear of a/6 <112> on each close-packed plane. The reverse transformation can be effected in a similar way by a/3 (1010) dislocations moving over every other basal plane of the hexagonal phase. Transformation theories2, 7- 12,14 differ in the details of the nucleation of the transformation and the propagation of the partial dislocations from plane to plane. EXPERIMENTAL PROCEDURE Nickel and cobalt rods supplied as 99.999 pct pure were induct ion-melted together under a vacuum of about 10-5 torr in a 97 pct alumina crucible. An alloy containing 30.5 pct Ni was found to have the desired transformation range, with an Ms near -10°C and an j4s in the vicinity of +10O°C. The ingots were swaged to &--in. rod and electron beam zone-leveled in a 10-6 torr vacuum. This procedure resulted in 12-in.-long single fcc crystal rods (designated I to VII) from each of which several tensile specimens of identical orientation were made. Chemical analysis of the bar ends indicated no contamination or gross segregation and no micro segregation was seen in electron micro-probe scans. Tensile specimens with a 9/32-in.-sq by 1-in.-long gage section were spark-machined from the rods and then electropolished or chemically polished to remove the machining damage and to provide a flat surface

Jan 1, 1970

"A commercially available through-the-earth (TTE) communications system was evaluated at an active underground longwall mine in West Virginia. This TTE system uses electricfield (E-field) sensing to send text-based communications through two separate antenna arrays connected in parallel. Each antenna array is composed of interconnected, grounded metallic rods or other such structures. Two-way communication between subsurface locations was investigated in this study using various antenna configurations. This field study was conducted as a part of a larger multisite evaluation of available TTE systems in an effort to determine their operational sensitivities. IntroductionWireless, through-the-earth (TTE) communication technology is designed to achieve point-to-point communication through solid strata using very low frequency (VLF) and ultra-low frequency (ULF) electromagnetic waves. Using this approach, communications are established without the need for intermediary communications infrastructure. As a result, TTE systems have the potential to provide reliable, robust communications between surface and underground personnel. Exploration into the use of TTE technology for this purpose dates back to the 1920s (Jakosky and Zellers, 1924; Pittman, Church and McLendon, 1985), but U.S. permissibility requirements slowed the development of TTE equipment for widespread implementation (Durkin 1980; Pittman, Church and McLendon, 1985). One of the primary challenges in producing wireless TTE communications is the counteraction of signal attenuation when propagating through solid strata (Barkand, Damiano and Shumaker, 2006; Wadley, 1949). The long wavelengths of TTE transmissions make them well-suited for reducing the rate of attenuation. However, even when operating within the VLF to ULF range, the performance of TTE systems is still affected by geologic and anthropogenic factors (Geyer, 1973; Geyer and Keller, 1976; Geyer, Keller and Ohya, 1974; Jakosky and Zellers, 1924; Large, Ball and Farstad, 1973). Although commercially developed TTE systems have demonstrated the ability to communicate in a variety of conditions, their range and performance have been highly varied (Barkand, Damiano and Shumaker, 2006; Geyer and Keller, 1976; Geyer, Keller and Ohya, 1974; Ilsley, Freeman and Zellers, 1928; Jakosky and Zellers, 1924; Yenchek et al., 2012)."

Sep 1, 2016

By R. P. King

A new device, called the dual impact load cell, has been developed and built at the Comminution Center to measure fracture energy and damage accumulation in brittle particles that are subject to impact. The results show that damage accumulation during impact is not a significant factor in determining the fracture energy or the particle strength. However, predamage induced by thermal pretreatment of the particles has a significant effect on both fracture energy and particle strength.

Jan 1, 1995

By C. S. Duncan, S. Scuro, D. R. Muss

Work is vepurted which was aimed at accentuating the pec14liar attributes of the GaAs laser diode, namely its sutzull size and its high efficiency. This has been done by reducing- transport losses in the bulk p and n regions of the diode and combining many of. these diodes into series stacks with common optical cazlities. The result of this effort is a nearly monochromati source at about 8450A With a luminous areu 0.05 by The GaAs laser diode is an attractive pulsed light source in the near ir because of its ability to emit very large pulse powers and its small size. In addition to this, the device is efficient; and the higher the 0.05 cm emitting peak pulse po we rs at greater than 300 LC at repetition rates below 200 pps into a cone about 0.01 steradians when operated at 77°K. The results of nzeasuvetnents of peak optical power and spectra frorr~ these stacks are reported and some conclusions are drawn about the vole the individual diodes play in the stacked operation. peak output power, the more efficient it is. The limit for the amount of power that these diodes can emit is the transient and average dissipation associated with the pumping pulse. This power dissipation arises primarily from transport across the bulk regions of the diode; this fact, along with the relatively low thermal conductivity of the GaAs, led us to the conclusion that higher power

Jan 1, 1968