An Economic Study of Specialized Swine Production Possibilities in Southeastern South Dakota

The American farmer has made tremen4ous improvements in his productive capacity and ability since the Colonial period. These improvements have been taking place at a constantly accelerating rate. Much of this improvement has been due to increased specialization. The growth of urban population is an indicator of the rapid development of specialization. During Colonial times, at least nine-tenths of the population was engaged in farming, and as late as 1870, half of all workers were s till engaged in agriculture. Less than twenty percent of the nation\u27s labor force is now employed on the nation\u27s farms. In addition to a far smaller percent of the population employed in agriculture now than in the past, considerable more agricultural products per capita of the total population are produced

Instrumentation program for rock mechanics and spent fuel tests at the Nevada Test Site

This report contains a discussion of an instrumentation and rock mechanics program recommended for consideration as part of the overall Lawrence Livermore nuclear waste storage program at NTS. It includes a discussion of (1) rationale for the heater tests, spent fuel facility evaluation, heated room tests, (2) recommended instrumentation types together with estimated delivery schedules, (3) recommended instrumentation layouts, (4) other proposed rock mechanics tests both laboratory and in situ, and (5) data acquisition and reduction requirements

Az adófizetési hajlandóságot befolyásoló tényezők

Down-The-Hole (DTH) percussion tool is recognized for its high average rate of penetration (ROP), when drilling medium hard to very hard rock formations. This ROP which depends on the bit-rock contact conditions at the well bottom to efficiently transfer the impact energy to an intact rock can be maximized for certain parameter sets, including the static weight on bit (WOB, also known as thrust force/feed force). Indeed, recent experimental and numerical investigations of the bit-rock interface (BRI) have revealed an optimum WOB which is rooted in the dependence of the BRI law on theWOB force. That is an optimal state of pseudo-stiffness at the BRI can be obtained with the appliedWOB for which the impact energy transmitted to rock is maximized. Therefore, accurate estimation and control of the BRI stiffness is crucial in order to optimize drilling operation. In this paper, a numerical solution is proposed which can estimate the state of drilling dynamics and evolving BRI stiffness. This approach combines a 1D phenomenological percussive drilling model accounting for the longitudinal wave transmission during bit-rock interaction and a joint Unscented Kalman Filter (UKF) designed to simultaneously estimate the unknown parameters in the nonlinear BRI stiffness expression as well as the inaccessible states at the BRI. The results show that this approach has the potential to provide an accurate estimation of the percussive drilling dynamics and nonlinear BRI stiffness evolution over a wide range of initial conditions and static deformations that induced from changing WOB.acceptedVersio

A drifting impact oscillator with periodic impulsive loading: Application to percussive drilling

Peer reviewe

Prediction of near field overpressure from quarry blasting

This paper investigates the propagation of airblast or pressure waves in air produced by bench blasting (i.e. detonation of the explosive in a row of blastholes, breaking the burden of rock towards the free vertical face of the block). Peak overpressure is calculated as a function of blasting parameters (explosive mass per delay and velocity at which the detonation sequence proceeds along the bench) and the polar coordinates of the position of interest (distance to the source and azimuth with respect to the free face). The model has been fitted to empirical data using linear least squares. The data set is composed of 122 airblast records monitored at distances less than 400 m in 41 production blasts carried out in two quarries. The model is statistically significant and has a determination coefficient of 0.87. The formula is validated from 12 airblast measurements gathered in five additional blasts

An evaluation of some innovative fragmentation systems for oil shale

This report describes a large-scale underground mining method, large-hole stoping, using some innovative fragmentation systems (buffer blasting, continuous loading/hauling, and mechanical miners for development). This study includes a literature review and an experimental study of one of the key design factors--buffer blasting. The purpose of the buffer-blasting experiments is to examine the swell that is necessary to achieve satisfactory fragmentation results. The study also includes a technical and economic evaluation of the new mining method compared with conventional room and pillar mining. The purpose of this study is to examine innovative methods that exist today and may provide a more efficient mining system than that currently used. Note that this is a conceptual study, and that the mining for the two mine designs were compared using a daily production rate of 75,000 tones per day. This amount was chosen because it is the maximum amount possible for a rubber-tired room and pillar operation with only a one-shaft complex

Application of the results of excavation response experiments at climax and the Colorado School of Mines to the development of an experiment for the underground research laboratory

Large-scale underground experiment programs to examine excavation response have been performed at the Climax facility in Nevada and at the Colorado School of Mines. These two programs provided fundamental information on the behavior of rock and the effects of excavation; on instrument performance and configuration; and on the relationship between test geometry and test behavior. This information is being considered in the development of a major excavation response experiment to be carried out in the Canadian Underground Research Laboratory. 11 refs., 3 figs

PRELIMINARY REPORT ON GEOPHYSICAL AND MECHANICAL BOREHOLE MEASUREMENTS AT STRIPA

Four different systems of borehole instrumentation have been employed thus far at an experimental site at Stripa, Sweden where a series of hydrological and thermo-mechanical experiments are being conducted to examine the suitability of granitic rock for the storage of radioactive waste materials. Asuite of seven logs--neutron, gamma-gamma, resistivity, gamma ray, sonic, caliper, and temperature--operated in a borehole of 380-m depth located eleven zones where the rock permeability is expected to be enhanced due to the presence of open fractures. The sonic waveform record proved especially useful in this regard. Borehole measurements were also acquired in a large number of boreholes from 5- to 14-m length located in experimental drifts some 340-m underground. Here several physical properties, including the porosity, density, sonic velocity, and borehole rugosity, are generally quite uniform, with the exception of a few local chloritic zones and a few minor fractures. However, in situ determinations of the mechanical modulus with the CSM cell indicate substantial variability, with some apparent fracture control. Uranium and thorium concentrations are quite high in the Stripa granite, with local fluctuations associated with mineralogical changes as revealed by the gamma-ray log. Adifferential resistance probe appears promising as a sensitive detector of fine fracturing. Across-hole ultrasonic system indicates variations of a few percent in compressional- and shear-wave velocities, reflecting the presence of fractures and changes in fracture characteristics as the rock is heated in a simulated storage test. The geophysical and mechanical data are being compared with the results from core and television logging, with hydrological test data on static pressure and injection permeability, and with displacements induced by thermal loading