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The paper presents the development of an integrated computer aided design and planning of open cast mining, with the use of object-oriented modelling and geoinformation technologies, on the example of interaction of the subsystems on planning optimisation and freight traffics.

Dec 6, 2010

By Stephen Birch

THE Chitina mining district of Alaska is located at the headwaters of the Chitina and Copper Rivers. At present, the only producing min-ing properties are the mines of the Kennecott Copper Corpn. and the Mother Lode Coalition Co., which are situated 196 miles from Cordova the port of entry. The first claims, later acquired by the Kennecott Mines Co. and afterwards transferred to the Kennecott Copper Corpn., were discovered in 1900. The Copper River & Northwestern Ry., which connects the mines with tide water at Cordova, was completed in the spring of 1911. Contemporary with the construction of the railroad, aerial tram equipment was brought to the mines by pack train and a tramway, 3 miles, long, connecting Bonanza mine with the proposed railroad terminal, was finished, enabling shipments of high-grade ore to be made immediately on the completion of the railroad. A mill to treat the lower grade ore was begun the same year. The Kennecott company's holdings consist of 111 mineral claims. The Mother Lode Coalition Mines Co., which is controlled by the Kennecott Copper Corpn., owns 73 claims adjoining the Kennecott holdings. All data on operations and geology refer equally well to the Mother Lode property.

Jan 1, 1924

By M. Dworzanowski

The physical beneficiation of iron ore that has a wide particle-size distribution is problematic, regardless of the process applied, whether dense medium separation, gravity concentration, magnetic separation, or flotation. The problem of particle size is further compounded when there is a significant -10 µm fraction. Generally the approach to a wide particle-size distribution is to split into narrower size ranges and treat each separately. More often than not the -10 µm fraction is not treated but discarded. This approach results in a more complicated and expensive flow sheet and the loss of any potential value in the -10 µm fraction. Wet high-intensity magnetic separation (WHIMS) bench-scale test work was conducted on a haematite-rich material with a particle size of -200 µm. What made this material different was that it contained a 60% -10 µm fraction, hence discarding the -10 µm material was not an option. The objective of the test work was to determine how to maximize the recovery of the haematite across the full particle size range. Given the unusual particle size distribution, it was concluded that WHIMS would be the only practical beneficiation route. The -200 +10 µm and -10 µm fractions were treated separately and together under varying WHIMS conditions. For a given concentrate grade, the mass yield obtained was greater when the total particle-size distribution was treated. The inferred optimum conditions, using the same material, were tested on a pilot-scale WHIMS and similar results were obtained.

Jan 1, 2014

By M. T. Abasov

Among a host of challenges dictated by the explosively developing scientific and technical revolution, the improvement of control and management is one of the most essential problems. This problem is also of far-reaching importance for the oil and gas industries. An oil and gas extracting complex is an involved multilink system characterized by a great number of elements and by intricate interconnections between these elements. Of paramount importance for these systems is the quality of control. Any deviation of the control from the optimum reduces the effectiveness of the system and deteriorates its basic technical and economic factors. In case of large systems, even a relatively small deviation from the optimum may result in considerable material and power losses. Optimization of control of large production systems is therefore one of the basic means to enhance their effectiveness. The present paper discusses a development control problem for a multilayer gas deposit using the method of simultaneous exploitation of several strata by means of a single well. The optimum control is achieved by determining the dynamics of changes in the number of producing wells in a reservoir with regard to the depth of occurrence of these reservoirs as well as the difference in the time of introduction of the wells from drilling and their transfer to another reservoir. A mathematical model was constructed for the problem under consideration and a method was given to solve this problem. The problem was dealt with under the assumption that either each of the reservoirs or a part of them have vertically overlying areas and that there is no hydrodynamic interference between the horizons. It was

Jan 1, 1977

By C. Allen Born

There is a saying, the greater the gratitude, the shorter the speech. That puts me in a quandary, because while I am grateful for the honor you do me today, I also want to talk about a subject very important to all of us. A few months ago, when I was asked to submit a title for my talk, I chose "Quality where it counts." I did so because perhaps the most important thing we at Amax did in our restructuring was to commit to quality in all our businesses - quality people, assets, and operations. Together, they create quality performance, which produces quality growth and increased shareholder value - our prime corporate mission. We are dedicated to quality. At Amax, quality means everything. Today, I want to discuss quality in another context - the need for it in American education and what we have to do to achieve it. If we ignore this need, we will all suffer the consequences. And they will be upon us far sooner than the next century, barely a decade away. I think almost everyone in this room works for an organization that had to restructure in the 1980s. Mining companies that did not, just didn't make it. Well, we did. As an industry, we are seeing improved profits, positive cash flow, and a more competitive position in the world marketplace. But all the restructuring we have done, all the hard work, and all the pain that was part of it, will be in vain if, down the road, we do not have the educated people we need as workers. We need them to design, manufacture, and market the products that use the basic materials produced by the mining industry. Simply put, we are at a crisis point in education today. That is no new revelation. Nearly six years ago, the National Committee on Excellence in Education published its report, "A Nation At Risk." Since then, things have not gotten better. The Wall Street Journal, Business Week, US News & World Report, and Fortune have all recently published stories about the sorry state of education in the United States. The subject has become the topic of TV talk shows as well as national commissions, and for good reason. The pool of young people entering the US labor force is dwindling. In the next decade, 10 million fewer will enter the job market compared to the 1970s. But fewer of them will be qualified to do the jobs available to them. Here's why: • 20% of today's high school students drop out before they are 18 and another 20% graduate functionally illiterate; 40% of today's fourth graders think the world is flat; • 20% of today's sixth graders cannot locate the United States on a world map; • one of every three ninth graders cannot figure the change for a two-item meal - and I'm talking about a Big Mac and fries. These are not just problems of minority kids in big city ghettos. Fully 40% of all young working Americans cannot add up their lunch bill. Three out of every five college freshmen need some kind of remedial work. These statistics are frightening. Particularly so because, while the work force is becoming less qualified and our public education system is getting worse, our products and technologies are becoming more complex. We are approaching a time when we will have machines that recognize handwriting but people who cannot write. We will have technology to take voice commands, but people who do not know what they are talking about. The accelerating pace of technology is changing the nature of the job market. The fastest growing jobs now, and in the years ahead, are in professional, technical, and sales positions requiring the highest education and skill levels. Most of these jobs will require the use of a computer. Yet, 95% of today's graduating high school students have never laid a finger on a computer keyboard. While our education system is failing the students it is supposed to serve, other countries are doing far better. In a

Jan 1, 1990

By R. M. Raymond

The Mining Section of The National Safety Council recently sent out a questionnaire to operators, regarding the class of rope used, specifications required or obtained, factors of safety observed, methods of fastening ropes, lubrication, inspection, and points observed when rope is to be discarded. The answers received from this questionnaire, largely from metal mines, give interesting information, from which recommendations for safety practice on hoisting ropes are drawn. Depth of Mine The depth in the majority of cases noted is from 1000 ft. to 1500 ft. (304 to 457 m.) and records come from a number hoisting from depths of 2000 to 3000 ft. Hoisting is generally done in balance, with a few companies using counterweights. Seldom, more than two shifts are occupied in hoisting. A number of large operators limit the shift for engineers to 6 hr. A few of the larger operators have separate hoists for men and supplies, with a higher class rope for men. The range of loads varies from 7 to 17 tons and greater in a few cases, with a balanced weight of 4 to 7 tons. Size or Drums and Sheaves The size of drums and size of sheaves are generally in accordance with recommendations of rope manufacturers. Only one-half of the operators use grooved drums; one, The Sulphide Corpn., New South Wales, uses wood-lagged drums. Very few operators have drums capable of holding all the rope in a single wrap. Cone drums or cone and cylinder drums, in the mines heard from, are very rare. A few mines of shallow depth use a small drum and large-sized sheave. While this may be allowed, and in some cases is all right, the size of drum and sheave should be fully equal to that recommended by the rope manufacturers and should be at least 60 to 100 times the diameter of the

Jan 1, 1923

By R. M. Raymond

The Mining Section of The National Safety Council recently sent out a questionnaire to operators, regarding the class of rope used, specifications required or obtained, factors of safety observed, methods of fastening ropes, lubrication, inspection, and points observed when rope is to be discarded. The answers received from this questionnaire, largely from metal mines, give interesting information, from which recommendations for safety practice on hoisting ropes are drawn. Depth of Mine The depth in the majority of cases noted is from 1000 ft. to 1500 ft. (304 to 457 m.) and records come from a number hoisting from depths of 2000 to 3000 ft. Hoisting is generally done in balance, with a few companies using counterweights. Seldom, more than two shifts are occupied in hoisting. A number of large operators limit the shift for engineers to 6 hr. A few of the larger operators have separate hoists for men and supplies, with a higher class rope for men. The range of loads varies from 7 to 17 tons and greater in a few cases, with a balanced weight of 4 to 7 tons. Size or Drums and Sheaves The size of drums and size of sheaves are generally in accordance with recommendations of rope manufacturers. Only one-half of the operators use grooved drums; one, The Sulphide Corpn., New South Wales, uses wood-lagged drums. Very few operators have drums capable of holding all the rope in a single wrap. Cone drums or cone and cylinder drums, in the mines heard from, are very rare. A few mines of shallow depth use a small drum and large-sized sheave. While this may be allowed, and in some cases is all right, the size of drum and sheave should be fully equal to that recommended by the rope manufacturers and should be at least 60 to 100 times the diameter of the

Jan 1, 1923

By A. Martens

When I was honored with an invitation from the American Institute of Mining Engineers to present a paper at the Chicago meeting on the microstructure of iron, I hesitated about accepting, as the short interval that would remain at my disposal, after other pressing matters had received attention, could not but seriously affect the work of preparing such a paper. Unfortunately my fears have been realized and my work is neither completed, nor yet as comprehensive as I should desire. Mindful of my promise, however, and recognizing that 1 have reached a point where the results of my researches may prove suggestive, I am led to present them now, trusting that this brief explanation map secure indulgence for whatever deficiencies the paper may disclose. So far as my knowledge of published memoirs and treatises extends, microscopy cannot yet be said to possess a really firm foundation. In few cases only has any systematic development of the methods of investigation been undertaken, and broad gaps remain to be filled. It is not yet possible, therefore, to give a complete survey of the field, or, indeed, to supply a text-book on microscopic metallography. As Mr. F. Osmond, of Paris, a distinguished member of our profession, has undertaken to prepare for the Chicago meeting a historic review of the work actually accomplished I need not touch on that branch of the subject; but before entering upon my special theme, it may not be out of place for me to introduce certain explanations, as furnishing reasons for the course 1 have hitherto pursued, and to offer some suggestions for the further development of the methods of microscopic investigation. In microscopic metallography, the examination has to be conducted principally with incident light. Objectives of low power, in which the distance between the front lens and the abject is considerable, are adapted for directly incident light, and in such cases the relatively great depth of the image renders it possible to examine

Jan 1, 1894

By R. Taggart, R. H. Ericksen, D. H. Polonis

Transmission electron microscopy techniques hare been used to study the spontaneous marfensite phase that forms during the thinning of Ti-Cr alloys. The structure of this phase has been found to differ. from the hcp martensite and has been identified as a clisforted fcc lattice. The spordaneous marlensile in this system is interpreted as a metastable isomorph of the equilibriunz TiCr, phase. WHEN thin-foil specimens for transmission electron microscopy were prepared from metastable alloys of the Ti-Cr system, a spontaneous transformation occurred' when the foils contained the untrans-formed 0 phase or two-phase mixtures of the 0 and w phases. The purpose of this paper is to examine the relationship that exists between the crystal structure of the spontaneous product and that of the matrix. The differences between the martensite transformation that occurs in the bulk material and the spontaneous reaction that occurs during the preparation of thin foils are compared with the observations that have been reported for similar phenomena in a commercial titanium alloy.' A spontaneous reaction that exhibits characteristics similar to a martensite transformation has been reported to occur in thin foils prepared from the retained metastable structures of several alloy systems.1'3"7 ~ull~ observed such a spontaneous reaction in 0 brass and attributed the apparent increase in the martensite transformation temperature to a decrease in the non-chemical free energy associated with bulk strain energy. He also showed that the spontaneous product did not have a specific habit plane, but that its orientation relationships to the parent matrix were dependen on the thickness of the transforming region. It has also been pointed out by Breedis6 that in thin films the absence of the constraints imposed by a bulk matrix can cause different requirements for the martensite plate interface and lattice distortion which is reflected bv a dependence of the transformation mechanism on the specimen geometry. In the case of the spontaneous reaction reported for Au-Zn alloys7 a definite habit plane was determined and shown to correspond with the habit plane calculated on the basis of the Bowles and Mackenzie crystallographic theory of the martensite transformation.'- lo EXPERIMENTAL PROCEDURE A series of titanium alloys containing 5.5, 5.9, 6.4: 7.6, 8.0, 11.3, and 18.7 at. pct Cr were prepared from high-purity (iochrome) chromium and iodide-grade titanium by levitation melting. The experimental procedure used for sectioning the alloys and for thin-foil preparation has been reported in an earlier paper.' X-ray diffraction patterns were obtained using a 114-mm Debye-Scherrer camera and Cu-Ka radiation. In order to minimize fluorescent radiation from the specimen, a strip of aluminum foil 0.002 in. thick was placed in contact with the X-ray film. After a specimen was removed from the camera: an additional X-ray experiment was performed, to insure that no spurious lines were obtained due to the presence of the aluminum foil. The interstitial impurity analysis for the alloys used in this study was as follows: oxygen, 100 ppm: hydrogen, 30 ppm: nitrogen, 28 ppm. EXPERIMENTAL RESULTS Electron diffraction patterns were obtained from several individual crystals of the spontaneous marten-

Jan 1, 1970

By Bruce D. McCellan

INTRODUCTION The gathering arm loader was patented by Joseph Joy in 1916. This unique machine motion became the standard of the industry and is used on underground loaders and continuous miners throughout the world. Figs. 1 and 2 show two types of gathering arm loaders. The gathering arm loader is a crawler-mounted ma¬chine primarily used for loading coal in a conventional mining system. Other uses also have been found for this machine in noncoal mines and other industries. MECHANICAL ASSEMBLIES The front or loading end of the machine, commonly called the head, consists of a tapered structural frame, hinged at the rear to the chassis and riding the ground at the front. Two bevel-gear cases are mounted in the head. They are connected by a timing shaft, which also acts as a conveyor drive shaft on most models. An eccentric disk attached to each gear case drives the gathering arms. The rear of the arms are attached to a swivel assembly. The motion derived from this arrange¬ment gathers loose material from the ground directly in front of the machine and loads it into the conveyor. Power for this drive is provided by two electric motors mounted under the gathering head. A speed reducer attached to each motor provides a gathering arm speed of approximately 5.2 rad/s (50 rpm). A torque limiting clutch is provided on each reducer to guard the system against sudden impact loading and continual overloading of the motors. The conveyor consists of an open box section through which a universal-type chain carries the ma¬terial to the rear of the machine, where it is discharged into the haulage vehicle. The chain is driven by a sprocket located on the timing shaft between the two gathering-head bevel-gear cases. On some large loader designs, primarily for noncoal applications, the chain is driven by a separate gear motor at the discharge end of the conveyor. However, the system driven by the timing shaft is used most widely. The conveyor frame is hinged just to the rear of the gathering head. It can be raised or lowered by hydraulic cylinders to the desired discharge height. The conveyor frame also is designed to pivot 0.79 rad (45°) either side of the center, just to the rear of the chassis. This feature increases the maneuverability of the ma¬chine and makes it possible to discharge material into the haulage system when in tight quarters such as when turning a crosscut. This function also is controlled by a hydraulic cylinder. The chassis of the loader consists of two crawler frames and cross members, holding the frames in position. The frames are either welded or cast as¬semblies. Replaceable wear runners are provided on the frames to take the wear generated by the crawler chain. An adjustable take-up idler keeps the crawler chain in proper adjustment for maximum life. The drive system for the crawler chains varies with the manufacturer, but it generally is one of two basic designs. One system provides a traction motor for each side of the machine, coupled to a speed reducer. A spur and bevel-gear train transfers power to the sprocket, which drives the crawler chain. Directional control is achieved by disk-type clutches. The other system also uses a motor for each crawler, coupled to a speed reducer. A roller chain drives the sprocket, which in

Jan 1, 1982

Milling circuits are known to be difficult to control. In order to address these difficulties, it was decided to develop and test a model predictive controller (MPC) for a milling circuit. A milling simulator was written using Microsoft Visual C++ and used to design and test the MPC controller. Due to the large number of tuning parameters in a controller of this type, an optimizing algorithm was written that automatically tunes the controller. Good, robust control was obtained when the controller was tuned using this algorithm. Control was further improved by combining feedback and feed forward control and by using quadratic programming in the MPC algorithm. The movement of the manipulated variables was reduced by using a novel technique that allows the controlled variable to vary within a specified region around the set point. An optimiser controller was also successfully implemented to control the circuit at its maximum throughput.

Jan 1, 2000

By V. Dinesen

"Grinding is simply the function of reducing particles in size or creating new surface areas. This may be accomplished by many means but we will only concern ourselves with the continuous grinding process as performed in a revolving drum or mill, containing a grinding media. Such a mill consists essentially of a feed head, a cylindrical shell section and a discharge head. To prevent internal wear of these parts it is customary to attach replaceable linings over the wear areas. The specification and design of these mill liners is more important than generally conceded. As they reduce the effective internal volume of the mill, they will consequently affect the whole mill ·design and operation.A number of mill designs of various sizes are available for combined crushing and grinding of materials within a wide size range. For simplif1cahon purposes we will refer 1n particular to conditions relating to standard mill shapes having a length which is greater than the diameter. Such mills usually rotate at speeds between 60% to 85% of the critical speed and may, depending on the grinding media used, be classified as rod mills, ball mills and pebble mills.LINER MATERIALSA great variety of materials have been and are being used for mill linings. These include wood, ceramics and cements, rubber and plastic compounds, rolled and forged steels, cast steels and cast irons, both plain, alloyed and specially treated.The choice of a liner material depends on many factors. In both dry and \\.:et grinding, it may be necessary to consider product purity, colour, chemical reaction etc. but for our purpose we \viii refer to wet grinding operations as generally used within the mining industry."

Jan 1, 1972

To reduce operator exposure to drilling noise from roof bolting machines. Background Noise-induced hearing loss (NIHL) is a prevalent occupational illness in the United States. Studies indicate that 70%?90% of miners have NIHL significant enough to be classified as a hearing disability. Mine Safety and Health Administration studies indicated that roof bolting machine operators are among those overexposed to noise. Field studies support the premise that, on average, drilling is the loudest noise source to which a roof bolting machine operator is typically exposed and contributes greatly to the operator?s noise exposure. The National Institute for Occupational Safety and Health (NIOSH) has further determined that the drill steel and chuck radiate a significant amount of noise during drilling. To address this noise hazard, NIOSH developed a collapsible drill steel enclosure (CDSE) to encapsulate the drill steel during the drilling portion of the roof bolting machine duty cycle. In addition, NIOSH is collaborating with J. H. Fletcher & Co. in the continued development of a CDSE.

Sep 1, 2008

By Fred G. Hewett

Cassiar Mine in northern British Columbia began development in 1952. The deposir is found on rhe west limb of rhe McDame Synclinorium in a Mississippian serpentinite body. The serpenltntte, one of the McDame l ntrusives, imrudes Sylvester Group . rocks, which comprise a Lare Devonian to Early M1ss1ss1pptan eugeosync/inal sequence of argillites, quarrzires and volcanics. The foorwall conracr berween Sylvester Group rocks and rhe serpenrinire is a marked zone of broken and incomperent argillite and graphitic schist. The less marked hang- 111gwall contacr 1s a band of indurated argillite. The JurassicCretaceous emplacemenr of the Cassiar Graniric Barholilh is responsible for mosr of the numerous )aims, faulrs and shear zones found in the serpentinite body. Faulting occurred borh before and after asbestos formation. Asbestos is mined from an open pit ar rhe rate of 4,535 ronnes daily. It passes from the pir along a rramline to the mill, where it is concen/rared into nine direcr milling grades. Packaged fibres travel ro over 40 counrries around rhe world for use in the texrile, cemenr and other industries.

Jan 1, 1984

By N. M. S. Balbinot, A. L. Rodríguez, C. M. Mahlmann, R. de C. de S. Schneider

The use of sunflower oil co-products it was studied for production thermoplastic composites. Thermoplastic composites have been processed in polyethylene matrices of virgin linear low density polyethylene (LLDP) or recycled. Samples have been formulated with 10% mass fraction of sunflower bran, seed coat and mixture of bran and seed coat. The material characterization has been achieved by mechanical tensile test and Shore D hardness and by density physical testing. The results have demonstrated better properties to thermoplastic composites with sunflower seed coat.

Jan 1, 2008

By D. E. M. Plaumann

"The wet grinding of asbestos has attracted the attention of engineers for many years as a means of improving fibre liberation from the ore. Today, added impetus for wet grinding has resulted from a need to minimize worker exposure to asbestos dust in conventional dry mills using air, as well as a need to provide a cleaner, technically superior fibre for use by product manufacturers. However , high viscosities of asbestos slurries create transport and grinding difficulties which have been a factor impeding use of a wet grinding process.Laboratory evaluation of reagents to reduce viscosities of asbestos slurries found that one reagent, XFS-4272.00, reduced the viscosity of a 35% (by weight) slurry by 75%. The impact of XFS-4272.00 on actual grinding parameters were evaluated using a pilot plant rod mill. Slurries containing 78% solids and XFS-4272.00 were successfully milled and asbestos fibres from that milling compared favourably in liberation and relative surface area to asbestos fibres obtained from milling a 4% slurry without additives.IntroductionAlthough the use of asbestos has been declining over the last few years, the large deposits of chrysotile in eastern Canada (Quebec in particular) remain very important. Asbestos production in Canada stands ninth in volume for mineral production with over 740 000 tonnes produced in 1985. Of this quantity, 722000 tonnes were exported with a value of $446 million . Canada is second in world production of asbestos behind the U.S.S.R ."

Jan 1, 1988

By Edward F. Nagle

Instrumentation engineers have recently devised practical methods of metering the net solids flowing in a hydraulic mixture. The solids flow rate is determined by measuring the specific gravity and the flow rate of the mixture. T e specific gravity is measured by a variation of the bubbler system. The flow measurement is made by a somewhat unorthodox orifice requiring field calibrations. The linear mixture flow signal is then multiplied by the specific gravity signal, which is directly proportional to the percentage of solids in the mixture, to produce a linear solids Slow rate signal. The computations in this system are performed by Sorteberg pneumatic relays. Having obtained this measurement, integration and automatic control of hydraulic solids flow are available. This system is useful in mining, drilling and dredging industries. It provides maintenance of the net solids flow rate and reduces power consumption. Automatic control will provide rapid stabilization of net solids flow rate and release operators from making menual adjustments. The advantages of this application are economy of operation and increased pump efficiency, This paper describes a hydraulic solids flowmeter system installed aboard a dredge. Its purpose is twofolds:- 1. 20 provide a summation of the net solids flowing 2. To make available a practical guide for the drag tender operator. (Dwg. GSD-2219)

Jan 1, 1958

By Avi Shonberg

With the advancement of offshore wind farm projects towards deeper waters and larger wind turbine generators, founda- tion solutions other than the monopile have received increasing attention over the past 5 years. Monopiles are the most commonly used foundation solution for offshore wind turbines, with 82% in European waters founded on monopile foundations (EWEA, 2019). However, 2018 saw a record number of suction bucket jacket (SBJ) structures, which consist of a three-legged jacket sup- ported by a suction bucket at each leg (Figure 1), installed for offshore wind. applications. SBJs have now been installed successfully at the Borkum Riffgrund 1, Borkum Riffgrund 2 and Aberdeen Bay offshore windfarms. Suction-installed foundations, referred to in this paper as suction buckets, suction caissons, suction piles or suction anchors, have been widely used in the offshore industry since the early 1980s for a range of offshore applications predominantly as anchors for floating offshore structures - where they are "the most widely used anchor types for deep-water mooring applications" (McCarron, 2011). Suction buckets, installed using pumps that generate suction forces by creating a pressure difference between the inside and outside of the bucket, allow for the installation to be undertaken with minimal noise and without the use of mechanical force. Therefore, a key difference between suction-installed foundations and other foundation types is that the installation design, which must consider the soil type, soil strength and installation specific risks (for example, soil stratification with significant differences in permeability) may have a direct influence on the dimensions of the foundation. While the number of SBJS installed for offshore wind applications has increased significantly in recent years, the installation process for SBJ struc- tures is yet to become standard practice and is considerably more complicated than the installation process for mon- opiles. This paper provides a brief

Jul 1, 2022

By John D. Meahin

THE use of digital methods for generating crystallo-graphic data is well-established and many programs are now available. Transmission electron microscopy usually requires a knowledge of the electron diffraction pattern which is obtained by plotting a planar section through reciprocal space. With cubic symmetry these sections are very easily produced, but with hexagonal and lower symmetry systems considerably more labor is involved. Johari and Buchanan1 have written a Fortran program for generating standard projections and along similar lines we have produced a short but completely general program for generating any section through reciprocal space. The required inputs are the lattice parameters and angles for the real crystal. The Miller indices of the direction [U, V, W] parallel to the electron beam are then specified and the program will generate the Miller indices of the plane normals perpendicular to [U, V,, W] up to some specified integer. A subroutine can be inserted to test for forbidden reflections if desired. We have used such routines for fct and hcp crystals. As each permitted index is generated it is printed or punched out and no storage arrays are utilized in the computer. The normal diffraction pattern corresponds to the zero-order Laue zone, but with thin crystals or crystals of large lattice parameters the higher-order Laue zones may contribute to the diffraction pattern. Accordingly the program will generate successive Laue zones and project them onto the zero-order zone. The output of the program first lists the zone axis [C, V, W] and the Laue zone, and then gives a list of permitted reflections and the corresponding XP and YP coordinates of the reciprocal lattice point in angstroms-'. In addition, ZP, the perpendicular distance of the reciprocal lattice point from the (U, V, Ur) plane in reciprocal space is given, as is the reciprocal interplanar spacing. In the case of the zero-order Laue zone ZP is zero. A diffraction spot from the higher-order Laue zones will be very slightly displaced from the computed coordinates as its position in an actual pattern is given by projection along the diffracted beam2 and not along [u, V, w]. For any given electron wavelength this correction could be readily incorporated into the program, but as it only amounts to -1 pct it was decided to leave the program in its most general form, i.e ., a computation of points

Jan 1, 1970

By Venkata S. Vutukuri

Compressive strength of cylindrical specimens of a model material and sandstone with various diameter/height (d/h) ratios was determined in unconfined compression tests. It was observed that the compressive strength increases with increase in d/h ratio. Triaxial compression tests were also conducted on the specimens of the same materials with a d/h ratio of about 0.47. It was observed that the axial stress at failure increases with increase in confining pressure. A very interesting correlation was found between the effect of d/h ratio on compressive strength in unconfined compression tests and the effect of confining pressure on axial stress at failure in triaxial tests. The relationships between d/h ratio and confining pressure, s3 in MPa are:- For model material - s3 = -0.95 + 1.7957*(d/h) 0.7883. For sandstone - s- (-0.4554 + 0.9888* (d/h) 1.0355. The correlation coefficients for these equations are 0.9997 and 1. These equations are valid for d/h ratios of up to 10.

Jan 1, 1993