Determination of roof bolting parameters for the space near the face in developing placer deposits with filling

1989 ◽  
Vol 25 (6) ◽  
pp. 569-572
Author(s):  
N. L. Kychkin ◽  
E. E. Petrov ◽  
V. Yu. Izakson ◽  
G. G. Sugarenko
2021 ◽  
Vol 11 (15) ◽  
pp. 6948
Author(s):  
Gabriele Cervino ◽  
Sergio Sambataro ◽  
Chiara Stumpo ◽  
Salvatore Bocchieri ◽  
Fausto Murabito ◽  
...  

The aim of this study is to demonstrate the use and the effectiveness of cephalometry and golden proportions analysis of the face in planning prosthetic treatments in totally edentulous patients. In order to apply this method, latero-lateral and posterior-anterior X-rays must be performed in addition to the common procedure. Two main concerns for totally edentulous patients are the establishment of the vertical dimension and the new position of the occlusal plane. The divine proportion analysis was carried out by the use of a golden divider. The prosthetic protocol was divided into three steps and a case was selected for better understanding. Referring to the golden relations, if the distance from the chin to the wing of the nose is 1.0, the distance from the nose to eye is 0.618. This proportion is useful and effective in determining the correct prosthetic vertical dimension. The incisal margin of the lower incisor must be positioned between Point A (A) and protuberance menti (Pm) according to the gold ratio 0.618 of the total height A-Pm. Posteriorly the occlusal plane must be placed 2 mm below the divine occlusal plane (traced from the incisal margin of lower incisors to Xi point). A prosthesis made in accordance with cephalometric parameters and divine proportions of the face helps to improve the patient’s aesthetics, function and social personality.


Media Wisata ◽  
2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Sri Larasati

The purpose of this research is to know wtether knowledge, skill, responsiveness and communication skill influence in job competition for graduate student from Sekolah Tinggi Pariwisata AMPTA. The population in this study are student pf Sekolah Tinggi Pariwisata SMPTA that graduated in 2013 until 2016, the total population in this studt is 702 and 200 respondents who have worked taken as samples, samples were taken with non probability sampling technique and accidental sampling approach. Sampling approach using regression equations obtained results that through test results F (regression analysis jointly) may note that the value of F = 147.104 count with the significance of 0.000 < 0.05. The test results of the test F reinforced with testing the determination of the coefficient that shows the value of 74.6%) (0.746. From Test t (partially) can result in variable knowledge with a value of t = 3,173 and significance of the value 0002 < 0.05, variable skill with a value of t = 2,949 and value the significance of 0.004 < 0.05, variable attitude with a value of t = 2,688 and value the significance of 0.008 < 0.05, variable communication skill with a value of t = value and significance of 4,497 0000 < 0.05. From the above results can be known that the hypothesis posed was not proven in other words that all of these variables can be said to have a positive and significant effect simultaneously as well as partial toward the ability of STP graduates AMPTA in the face of competition in the world of work


2021 ◽  
Vol 36 (4) ◽  
pp. 61-71
Author(s):  
Serhii Nehrii ◽  
Tetiana Nehrii ◽  
Oksana Zolotarova ◽  
Serhii Volkov

The conditions of coal seam mining in the mines of Ukraine have been considered. The problem of conducting coal mining by longwalls in the conditions of soft adjoining rocks, which concerns the protection of mine roadways located near the face, has been revealed. In such conditions, the existing protective constructions are ineffective due to the fact that they yield and get pressed into the soft rocks of the footwall. This indicated the need for research into the geomechanical state of soft rocks of the footwall. According to the results of known studies on the mechanism of rock mass failure around roadways and the data of physical and mechanical properties of the coal mass, which is represented by soft rocks, the correlation dependence has been obtained, the use of which allowed for the determination of the parameters of the rock deformation diagram and the establishment of the stability criterion of footwall rocks under the protection means and stability conditions of the geotechnical system “protective construction – adjoining rocks.” They are the basis of a new approach to ensure the stability of the roadways, which are supported behind the faces, by controlling the stress state in the system “protective construction – adjoining rocks.” This may be the basis for the development of new methods of protecting roadways in conditions of soft adjoining rocks.


2019 ◽  
Vol 290 ◽  
pp. 03008
Author(s):  
Marek Kowalik ◽  
Tomasz Trzepiecinski

This paper presents the methods of experimental determining the depth of the plastically deformed top layer in the roller burnishing process. Precise determination of the depth of the plastically deformed layer is difficult due to slight deformation at the boundary of the plastic and elastic zone, the lack of visible changes in the microstructure, and minimal changes in microhardness. The article shows the method of original measurement method that consists in determining the thickness of the deformed layer using rings. The method involves the profilographometric measurements of the disconnected rings (samples) which are flat-faced in the package on the mandrel. The rings material deforms plastically in the surface layer causing wrapping of the end face of the ring in the direction of the rolling tool movement. After dismantling the ring pack, measurements were made on the face of each ring along radial directions, and the thickness of the deformed layer was observed on the microscope. The method was verified by microhardness measurements in the cross-section and cross-section of the ring. The results of deformation depth measurements were verified by finite-element-based numerical simulation.


1985 ◽  
Vol 4 (1) ◽  
pp. 31-44 ◽  
Author(s):  
Mark E. Rushefsky

This article examines the development of generic cancer risk assessment guidelines, or cancer policy, from 1976-1984. Risk assessment is considered the objective determination of the degree of risk from a substance. Risk management is the subjective determination of acceptable risk. However, uncertainties in the scientific foundations of cancer policy necessitate risk assessment inference choices, for example, over appropriate dose-response extrapolation models. Those choices are only partially scientific; they are also partially political. There is, as a result, an inevitable mixture of facts and values in cancer policy. The article explores ten inference controversies and evaluates how nine cancer policy documents resolved those controversies. It then traces the course of cancer policy development, showing how the Carter and Reagan administrations produced policies with difference emphases and considers several major challenges to cancer policy. The article then provides several justifications for cancer policy in the face of those challenges. It suggests, in the conclusion, that the controversies are unlikely to be resolved by science alone and politics will continue to influence the content of cancer policies.


1954 ◽  
Vol 45 (1) ◽  
pp. 96-103 ◽  
Author(s):  
John Hancock ◽  
C. P. McMeekan

1. A series of observations on the grazing behaviour of identical twin cattle on two contrasting systems of pasture management—rotationally and continuously grazed—is described.2. The rotationally grazed cows averaged only 11 min. (day/cow) shorter feeding time and 18 min. shorter ruminating time than their continuously grazed co-twins. The total time they spent in work was thus 29 min. shorter.3. While the average differences in total work over the whole trial was not great, the continuously grazed cows worked for appreciably longer daily periods at the time of seasonal feed shortage during which time the rotationally grazed cows were buffered by their pasture diet being supplemented with silage.4. The differences in grazing behaviour between the cows of the two treatments, together with the magnitude of the seasonal variations which occurred in both groups, indicated that dairy cows attempt to maintain a stable production in the face of adverse pasture conditions by increasing their feeding time.5. Previous conclusions based on observations of uniformly treated twins regarding the importance of heredity in the determination of grazing behaviour were fully confirmed.


Geophysics ◽  
2003 ◽  
Vol 68 (3) ◽  
pp. 900-910 ◽  
Author(s):  
Carlos A. Mendonça

This paper presents a new method to identify the regions over a 3D geoelectrical structure that produce major contributions to the electrical potential established in response to a dc source at the ground surface. The measured potential is represented by a sum of a known primary potential (due to a homogeneous half space) plus an unknown potential caused by conductivity inhomogeneities. Because the primary potential is continuous everywhere, the interfaces with a conductivity contrast act as sources or sinks of currents in order to maintain the continuity of the current density related to the primary flux. These disturbing face currents are responsible for the generation of the secondary potential, and mapping them over a given structure allows us to assess the regions where the secondary potential is generated. In general, the face currents vanish away from the source according to the decay of the primary electric field. For this reason, deeper investigations can be expected when using pole sources because its primary field decays with the inverse of the squared distance, instead of the cubed distance as for dipole sources. For thin sheets, the polarization decay with distance is one order higher than that for large 3D bodies, which makes the detection of a sheet yet more difficult. The quantification of the total face current over the structure for different positions along a profile helps one choose the proper electrode array and determine its optimum length. This is done in two steps: (1) identification of the offset where the dc source provides the highest polarization (face current) on the targeted structure, and (2) determination of the array length by locating the potential electrodes closest to the region with the highest polarization. This second criterion came from an analogy between the face‐current and artificial current sources, where it is intuitively seen that the resulting potential is highest close to the source. The proposed survey design technique is applied to three models commonly used in electrical exploration: a shallow conductive heterogeneity, a buried contact, and a thin conductive sheet.


1977 ◽  
Vol 47 (12) ◽  
pp. 795-801 ◽  
Author(s):  
T. J. Little ◽  
A. Hepworth

An alternative approach towards the measurement of loop length while in fabric form is proposed employing techniques of scanning electron microscopy and aerogrammetry. Distortions inherent in the recorded image have been taken into account by obtaining coordinates at intervals as determined by a micrograph of a cross-ruled grid. The lengths of all the resultant elements have been summed to obtain an estimate of the loop length, which was found to be 4–5% different from that obtained using the HATRA (Hosiery and Allied Trades Research Association, Nottingham, England) Course Length Tester. Some suggestions are offered for improving the estimated loop length by obtaining coordinates for both the face and back views of the same knitted loop. It is proposed that a similar approach would be beneficial towards an understanding of parameters governing the geometry of the knitted loop.


1973 ◽  
Vol 13 (2) ◽  
pp. 95-97 ◽  
Author(s):  
K. Karkola ◽  
M. Möttönen ◽  
J. Raekallio

An average of five people die annually in Finland of injuries caused by domestic animals. During the years 1957–68 the greatest number of deaths (30) was caused by horses, then by cows (18), and bulls (11). Dogs had killed 2 people and a cat and ram 1 person each. None of these deaths was a result of bites. Poisonous animals caused 22 deaths during the years 1936–68. Out of these 22, 20 were snake bites (the last one in 1961) and 2 were wasp stings (the last one in 1959). In 1969, a very unusual death was caused by pigs in Turku. A farmer was found dead in the pigsty among 12 pigs. He had lain there for about six hours. The autopsy showed that he had suffered from severe aortic stenosis. The viscera showed signs of cardiac failure. The pigs had gnawed the soft parts of the face, the eyes, all organs of the neck, and the genitals. Biochemical determination of histamine and serotonin proved that the wounds had been caused before death. Organs of the abdominal cavity had also been crushed. Bites and marks of pigs' feet were observed all over the body. Most likely, the man had fallen into the pigsty because of a heart attack. He had obviously been unable to move and was possibly unconscious when the pigs had savaged him.


Author(s):  
Mark Cerkovnik ◽  
S. Chang ◽  
Cary Griffin

Hybrid risers represent an excellent way to isolate the riser from most of the host vessel motions and thereby limit riser fatigue. A common arrangement features the riser supported by a buoyancy can via a tether chain. The tether chain is a cheap simple way to make the connection while providing flexibility for installation. However, in service the tether is under very high tension, and the chain is not really flexible in the face of small amplitude fatigue loads. The friction effectively “welds” the chain together. Moment and torque input to the system by first order vessel motions and vortex induced vibrations are carried through the chain and induce fatigue loading in the links. Analysis of the chain can be problematic because the determination of the detailed stress in the chain requires a refined FEA model with contact element between the links. From the global sense the analysis may require running hundreds of sea-state realizations in the time domain and the vortex induced vibration (VIV) assessment of thousands of current profiles. In this paper an efficient numerical method is described to rigorously determine fatigue damage at locations throughout the chain.


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