Features of rock pressure manifestations with the slice pillarless extraction of the Third potash layer at the Starobin potash salt deposit

Rock pressure manifestations in the development workings and the bottomhole region of the lower longwalls with the slice pillarless extraction of the Third potash layer of the Starobin potash salt deposit were studied. The stability of the development workings and the bottomhole space of the longwalls and the nature of interaction of the bottomhole lining with the adjoining rocks were studied. The intensity of manifestations of rock pressure in the longwalls and the nature of roof subsidence of the bottomhole region and its fall behind the face support were assessed. The nature of the loading speed distribution of the bottomhole lining for the treatment cycle was clarified. The rate of change of the loading before the heading and during this process and the loading rate of the bottomhole lining are taken as the main load support indicators for the treatment cycle. The cyclical nature of the change in the magnitude of these indicators in the interval of 10–12 treatment cycles is revealed. Their dependence on elastic stresses and creep of roof rocks after the formation of a new face is shown. The presence of the dynamic component of the load of the bottomhole lining due to the factor of the speed of the bottomhole movement was established. The influence of the deformation of rocks in the troughs of displacement on the bottomhole lining has been established. At the same time, it is shown that over a time interval of more than 2 years, the intensity of deformation of the rocks is significantly reduced. The possibility is shown how to determine the mean spacing of the secondary rock subsidence of the main roof and to identify anomalies associated with the boundaries of tectonic dislocations, faults and subsidence troughs by analyzing the dynamics of the accumulated deviations from the average of load support indicators. Recommendations have been developed on rational and safe parameters for maintaining the bottomhole region and the development workings of the lower longwalls with the slice pillarless extraction of the Third potash layer.

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Tectono-Sedimentary Evolution of the Cenozoic Basins in the Eastern External Betic Zone (SE Spain)

Geosciences ◽

10.3390/geosciences10100394 ◽

2020 ◽

Vol 10 (10) ◽

pp. 394

Author(s):

Manuel Martín-Martín ◽

Francesco Guerrera ◽

Mario Tramontana

Keyword(s):

Strike Slip ◽

Alluvial Fan ◽

Tectonic Activity ◽

Time Interval ◽

Se Spain ◽

The Third ◽

Sedimentary Evolution ◽

Marine Sedimentation ◽

Geodynamic Processes ◽

Early Paleocene

Four main unconformities (1–4) were recognized in the sedimentary record of the Cenozoic basins of the eastern External Betic Zone (SE, Spain). They are located at different stratigraphic levels, as follows: (1) Cretaceous-Paleogene boundary, even if this unconformity was also recorded at the early Paleocene (Murcia sector) and early Eocene (Alicante sector), (2) Eocene-Oligocene boundary, quite synchronous, in the whole considered area, (3) early Burdigalian, quite synchronous (recognized in the Murcia sector) and (4) Middle Tortonian (recognized in Murcia and Alicante sectors). These unconformities correspond to stratigraphic gaps of different temporal extensions and with different controls (tectonic or eustatic), which allowed recognizing minor sedimentary cycles in the Paleocene–Miocene time span. The Cenozoic marine sedimentation started over the oldest unconformity (i.e., the principal one), above the Mesozoic marine deposits. Paleocene-Eocene sedimentation shows numerous tectofacies (such as: turbidites, slumps, olistostromes, mega-olistostromes and pillow-beds) interpreted as related to an early, blind and deep-seated tectonic activity, acting in the more internal subdomains of the External Betic Zone as a result of the geodynamic processes related to the evolution of the westernmost branch of the Tethys. The second unconformity resulted from an Oligocene to Aquitanian sedimentary evolution in the Murcia Sector from marine realms to continental environments. This last time interval is characterized as the previous one by a gentle tectonic activity. On the other hand, the Miocene sedimentation was totally controlled by the development of superficial thrusts and/or strike-slip faults zones, both related to the regional geodynamic evolutionary framework linked to the Mediterranean opening. These strike-slip faults zones created subsidence areas (pull-apart basin-type) and affected the sedimentation lying above the third unconformity. By contrast, the subsidence areas were bounded by structural highs affected by thrusts and folds. After the third unconformity, the Burdigalian-Serravallian sedimentation occurred mainly in shallow- to deep-water marine environments (Tap Fm). During the Late Miocene, after the fourth unconformity, the activation of the strike-slip faults zones caused a shallow marine environment sedimentation in the Murcia sector and a continental (lacustrine and fluvial) deposition in the Alicante sector represented the latter, resulting in alluvial fan deposits. Furthermore, the location of these fans changed over time according to the activation of faults responsible for the tectonic rising of Triassic salt deposits, which fed the fan themselves.

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Variation of Congruences of Curves of an Orthogonal Ennuple in a Riemannian Space

Canadian Journal of Mathematics ◽

10.4153/cjm-1953-058-7 ◽

1953 ◽

Vol 5 ◽

pp. 519-523

Author(s):

T. K. Pan

Keyword(s):

Riemannian Space ◽

Rate Of Change ◽

Parallel Displacement ◽

The Third

Consider any three congruences of an orthogonal ennuple at a point of a Riemannian space. When one congruence is moved by local and a second congruence is moved by parallel displacement in the direction of the third congruence, the rate of change of cosine of the angle between the first two congruences is well known as Ricci's coefficient of rotation and has been extensively studied. It is the purpose of this note to investigate the corresponding rate of change, when the third congruence is replaced by an arbitrary one, in connection with parallelism and equidistance of congruences as studied by Miss Peters [2; 3].

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Pharmacokinetics of ethanol and its metabolite, acetaldehyde, and fetolethality in the third-trimester pregnant guinea pig for oral administration of acute, multiple-dose ethanol

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y86-182 ◽

1986 ◽

Vol 64 (8) ◽

pp. 1060-1067 ◽

Cited By ~ 41

Author(s):

David W. Clarke ◽

Nancy A. E. Steenaart ◽

Christopher J. Slack ◽

James F. Brien

Keyword(s):

Guinea Pig ◽

Amniotic Fluid ◽

Ethanol Concentration ◽

Fetal Brain ◽

Maternal Blood ◽

Time Interval ◽

Gas Liquid Chromatography ◽

Fetal Blood ◽

Third Trimester ◽

The Third

The pharmacokinetics of ethanol and its metabolite, acetaldehyde, were determined in the third-trimester pregnant guinea pig (56–59 days gestation) for oral intubation of four doses of 1 g ethanol/kg maternal body weight, administered at 1-h intervals. Animals (n = 4–7) were sacrificed at each of selected times during the 26-h study. Ethanol and acetaldehyde concentrations were determined by headspace gas-liquid chromatography. The maternal and fetal blood ethanol concentration–time curves were virtually superimposable, which indicated unimpeded bidirectional placental transfer of ethanol in the matemal–fetal unit. The blood and brain ethanol concentrations were similar in each of the maternal and fetal compartments during the study, which indicated rapid equilibrium distribution of ethanol. There was accumulation of ethanol in the amniotic fluid resulting in higher ethanol concentration compared with maternal and fetal blood during the elimination phase, which indicated that the amniotic fluid may serve as a reservoir for ethanol in utero. Acetaldehyde was measurable in all the biological fluids and tissues at concentrations that were at least 1000-fold less than the respective ethanol concentrations and were variable. There was ethanol-induced fetolethality that was delayed and variable among animals, and was 55% at 23 h. At this time interval, the ethanol concentrations in maternal blood and brain, fetal brain, and amniotic fluid were 35- to 53-fold greater and the acetaldehyde concentrations in maternal blood and fetal brain were four- to five-fold higher in the animals with dead fetuses compared with the guinea pigs with live litters. These data indicated that decreased ethanol elimination from the maternal–fetal unit was related temporally to the fetolethality.

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Rock pressure manifestations in longwalls due to changes in the order of caving

Soviet Mining Science ◽

10.1007/bf02497583 ◽

1972 ◽

Vol 8 (6) ◽

pp. 625-627

Author(s):

A. M. Ermolaev

Keyword(s):

Rock Pressure ◽

Rock Pressure Manifestations

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Use of U.S. Census Bureau Data to Expose Students to Dynamic Population Growth

The American Biology Teacher ◽

10.1525/abt.2017.79.7.572 ◽

2017 ◽

Vol 79 (7) ◽

pp. 572-577

Author(s):

Evan Lampert

Keyword(s):

Population Size ◽

Human Population ◽

Census Bureau ◽

Rate Of Change ◽

Time Interval ◽

World Population ◽

Quantitative Literacy ◽

Online Databases ◽

Dynamic Population ◽

The U.S

Global human population size and understanding how it has changed and will change in the future are important concepts for students. Here I describe exercises that use online databases provided by the U.S. Census Bureau to show students how both population size and the rate of change vary over time. In the first exercise, the U.S. population clock is used to calculate daily birth, death, and migrant and death rates, and how the world population clock is used to calculate the rate of change. These rates can be used to predict what the population size would be if the rates remained unchanged for a predetermined time interval. In the second exercise, historical data are used to determine the years with the most change in U.S. and world population size, then calculate how much larger the current population would be if those historical rates of change remained constant. These exercises have improved quantitative literacy while showing students current and historical trends in human population.

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Laboratory study of the effect of light on the emergence behaviour of eight species of commercially important adult penaeid prawns

Marine and Freshwater Research ◽

10.1071/mf9940043 ◽

1994 ◽

Vol 45 (1) ◽

pp. 43 ◽

Cited By ~ 30

Author(s):

TJ Wassenberg ◽

BJ Hill

Keyword(s):

Light Intensity ◽

Laboratory Study ◽

Carapace Length ◽

Rate Of Change ◽

Metapenaeus Ensis ◽

The Third ◽

Light Intensities ◽

Commercially Important ◽

Penaeus Merguiensis ◽

Effect Of Light

The emergence behaviour of eight species of commercial prawns (between 25.0 and 30.0 mm carapace length) was studied in the laboratory. All except Penaeus merguiensis were nocturnal: they emerged from the substratum in the evening when the light was dimmed and buried themselves in the morning, usually before dawn. P. merguiensis generally remained on the substratum during the day. The species can be grouped on the basis of their behaviour: the first group (P. plebejus and P. latisulcatus) was most sensitive to light, the second group (P. semisulcatus, Metapenaeus ensis, P. esculentus, M. endeavouri and M. bennettae) was less sensitive to light, and the third (P. merguiensis) was least sensitive to light. To find out what triggered emergence, two species (P. esculentus and P. plebejus) were exposed to different rates of light dimming at dusk. Both species responded to absolute light intensity, but the response of P. plebejus was affected by the rate of change of light intensity. The different responses of the species to different light intensities explains some of the differences in catchability in a multi-species prawn fishery.

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Rate of Change in Reinforcement Density as a Parameter of Behavioral Contrast

Psychological Reports ◽

10.2466/pr0.1980.47.3f.1071 ◽

1980 ◽

Vol 47 (3_suppl) ◽

pp. 1071-1075

Author(s):

Gerri E. Schwartz

Keyword(s):

Behavioral Contrast ◽

Variable Interval ◽

Reinforcement Rate ◽

Constant Component ◽

Rate Of Change ◽

Variable Component ◽

Reinforcement Density ◽

The Third ◽

Component Variable ◽

Baseline Values

One component (variable component) of a three-ply multiple schedule was gradually changed over 55 sessions from variable-interval (VI) 1-min. to VI 5-min. by exposing pigeons to the following sequence of values: VI 1, VI 2, VI 3, VI 4, VI 5-min. Subsequently, the reinforcement density in a second component (following component) was abruptly changed from VI 1-min. to VI 5-min. The effects of both gradual and abrupt reductions in reinforcement density were examined in the third component (constant component) in which the schedule remained unchanged. For all subjects, the greatest increase over baseline values occurred during the abrupt reduction in reinforcement rate.

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Time Determination and Time Keeping

Journal of Navigation ◽

10.1017/s0373463300027478 ◽

1948 ◽

Vol 1 (2) ◽

pp. 109-117

Author(s):

Harold Spencer Jones

Keyword(s):

Frequency Control ◽

Rate Of Change ◽

Time Interval ◽

The Earth ◽

Convenient Means ◽

Time Signals ◽

Time Determination ◽

The Mean ◽

Rotation Of The Earth ◽

Definite Manner

The rotation of the Earth provides the ultimate standard of time. As the fundamental unit of time we can use either the mean solar day or the sidereal day; these two units are related in a definite manner, so that when one is determined, the other can be inferred. The purpose of any timepiece is to subdivide the day into shorter intervals, and so give the time at any instant. No timepiece will give exact time; the error of the timepiece at some definite instant and the rate of change of that error, or, briefly, the rate, must be determined in order to extrapolate for the correct time at some subsequent instant. The accuracy of the extrapolation will depend upon the uniformity of the rate of the timepiece. Radio time signals sent out from an observatory, which is responsible for the determination and distribution of time, provide the most convenient means for deriving the error and rate of a timepiece. For normal navigational purposes an accuracy of about 0·05 seconds is adequate. But for the purpose of frequency control a very much higher precision is needed—but a precision in time interval rather than in absolute time. Some of the radio-aids to navigation depend upon the accuracy in standardization of frequency, so that high accuracy in time interval has become, indirectly, a navigational requirement.

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