scholarly journals The role of powered support in ensuring the proper longwall working cross-section area in rockburst-prone seams

2020 ◽  
Vol 305 ◽  
pp. 00081
Author(s):  
Zbigniew Lubosik ◽  
Sylwester Rajwa ◽  
Andrzej Walentek ◽  
Wojciech Masny ◽  
Aleksander Wrana
Keyword(s):  
Underground Mines ◽  
Hard Coal ◽  
Seismic Events ◽  
Negative Consequences ◽  
Cross Section Area ◽  
Section Area ◽  
Powered Support ◽  
Mining Conditions ◽  
Dynamic Phenomena

In Poland, for underground hard coal seam extraction, the longwall method is used. Retreat longwalls with natural roof caving in the gob are the most common. Currently it is estimated that about a half of the hard coal output in Poland originates from seams located in areas of rock burst hazard. The article shows information about 18 rock bursts, and 14 other seismic events which occurred between 2003 and 2012 in underground mines belonging to one of coal companies in Poland. In addition, negative consequences of those dynamic phenomena in the longwall workings are described. In the next part of paper, the most common types of damage to powered supports after the rock mass tremors and other dynamic phenomena in longwall workings are shown. In order to avoid damage of powered supports, in geo-mining conditions where dynamic phenomena occur, different types of protective means are applied. In the paper the methodology of assessing the powered support yield ability is described. At the end, an example of the assessed yield ability of a powered support in given geo-mining conditions of a longwall face affected by the seismic events is presented.

EFFECT OF BEDLOAD SEDIMENT NATURAL COMPOSITION ON GEOMETRIC AND DINAMIC CHARACTERISTICS OF CHANNEL FORMS

2018 ◽  
pp. 36-39
Author(s):  
N Ikramov ◽  
T Majidov
Keyword(s):  
Research Work ◽  
Laboratory Data ◽  
Hydroelectric Station ◽  
Negative Consequences ◽  
Movement Velocity ◽  
Reservoir Volume ◽  
Pump Station ◽  
Cross Section Area ◽  
Section Area ◽  
Bedload Sediment

The article brings up data on sediment diversity at watercourse bed and on their movement in the form of ridges. The ridge form movement of sediment leads to the reduction of reservoir volume and canal cross section area, which has an effect on their carrying capacity, filling of pump station forechambers and hydroelectric station pressure basins with sediment. The presence of sediment in flow leads to abrasive deterioration of pumps, water motors and pressure pipes and to other negative consequences. Research work tasks on the study of these effects have been examined with the purpose of preventing such negative consequences. On the basis of laboratory data diagrams and relationships were obtained for ridge length, height and movement velocity vs. sediment hydraulic and geometric sizes.

Abstract 313: STIM1 Silencing Reverses Pressure-overload Induced Cardiac Hypertrophy In Mice

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Ludovic O Bénard ◽  
Daniel S Matasic ◽  
Mathilde Keck ◽  
Anne-Marie Lompré ◽  
Roger J Hajjar ◽  
...  
Keyword(s):  
Ventricular Hypertrophy ◽  
Contractile Function ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Aortic Banding ◽  
Cross Section Area ◽  
Abdominal Aortic ◽  
Section Area

STromal Interaction Molecule 1 (STIM1), a membrane protein of the sarcoplasmic reticulum, has recently been proposed as a positive regulator of cardiomyocyte growth by promoting Ca2+ entry through the plasma membrane and the activation of Ca2+-mediated signaling pathways. We demonstrated that STIM1 silencing prevented the development of left ventricular hypertrophy (LVH) in rats after abdominal aortic banding. Our aim was to study the role of STIM1 during the transition from LVH to heart failure (HF). For experimental timeline, see figure. Transverse Aortic Constriction (TAC) was performed in C57Bl/6 mice. In vivo gene silencing was performed using recombinant Associated AdenoVirus 9 (AAV9). Mice were injected with saline or with AAV9 expressing shRNA control or against STIM1 (shSTIM1) (dose: 1e+11 viral genome), which decreased STIM1 cardiac expression by 70% compared to control. While cardiac parameters were similar between the TAC groups at weeks 3 and 6, shSTIM1 animals displayed a progressive and total reversion of LVH with LV walls thickness returning to values observed in sham mice at week 8. This reversion was associated with the development of significant LV dilation and severe contractile dysfunction, as assessed by echography. Hemodynamic analysis confirmed the altered contractile function and dilation of shSTIM1 animals. Immunohistochemistry showed a trend to more fibrosis. Despite hypertrophic stimuli, there was a significant reduction in cardiac myocytes cross-section area in shSTIM1-treated animals as compared to other TAC mice. This study showed that STIM1 is essential to maintain compensatory LVH and that its silencing accelerates the transition to HF.

scholarly journals Revamped Cooling of a Rectangular Shaped Chip Inserting a Highly Conductive Solid: Coupled vs. Uncoupled Conceptions

2017 ◽  
Vol 13 (2) ◽  
Keyword(s):  
Volume Fraction ◽  
Peak Temperature ◽  
Bottom Surface ◽  
Uniform Heat Flux ◽  
Heat Current ◽  
Cross Section Area ◽  
Section Area ◽  
Branching Patterns ◽  
Temperature Heat

The performance of highly conductive inserts embedded into a heated chip has been investigated in recent years. The role of the insert was to gather the heat current within the chip and remove it to a low temperature heat sink. The central goal of this study is to invoke several reconsiderations, which results in the plausible reduction of the peak temperature in a heated rectangular chip in comparison with the lowest peak temperature achieved in previous works. It is proved that for the configuration under study with its bottom surface receiving a constant uniform heat flux, the branching patterns of the insert must be avoided, instead the appropriate revisions in the architecture (width, location and cross section area) of the insert are accounted for the simple patterns. An uncoupled analytical solution for predicting the peak temperatures in the rectangular chip containing the cooling insert is also addressed. It is also proved that under the same volume fraction and thermal conductivity of the insert, the peak temperature can be reduced to 2.9 °C, which is 94% below the lowest temperature reported in the archival literature, which was around 50.5 °C.

Essential reformulations for optimization of highly conductive inserts embedded into a rectangular chip exposed to a uniform heat flux

2013 ◽  
Vol 228 (13) ◽  
pp. 2337-2346 ◽  
Author(s):  
MR Hajmohammadi ◽  
M Moulod ◽  
O Joneydi Shariatzadeh ◽  
SS Nourazar
Keyword(s):  
Heat Flux ◽  
Volume Fraction ◽  
Peak Temperature ◽  
Bottom Surface ◽  
Uniform Heat Flux ◽  
Heat Current ◽  
Cross Section Area ◽  
Section Area ◽  
Branching Patterns

Optimization of a highly conductive insert embedded into a heated rectangular chip has been lately investigated. The role of the insert was to gather the heat current within the chip body and remove it to a minimum temperature heat sink. The central goal of this paper is to invoke several reconsiderations, which result in excessive reduction of the peak temperature in the heated chip in comparison with the lowest peak temperature existed in the archival literature. It is proved that for the configuration under study with its bottom surface receiving a heat flux, the branching patterns of the insert must be avoided, in case the appropriate revisions in the architecture (width, location and cross section area) of the simple branchless patterns are considered. An analytical solution for predicting the peak temperatures in the chip is also addressed. It is demonstrated that under the same volume fraction and thermal conductivity of the cooling insert, the peak temperature is reduced to 2.9℃, which is 94% below the lowest temperature existed in the archival literature, which was around 50℃.

Influence of Magnetic Fields on Solar Hydrodynamics: Experimental Results

1977 ◽  
Vol 36 ◽  
pp. 143-180 ◽  
Author(s):  
J.O. Stenflo
Keyword(s):  
Solar Activity ◽  
Energy Balance ◽  
Magnetic Fields ◽  
Solar Atmosphere ◽  
General Problem ◽  
Solar Rotation ◽  
Active Regions ◽  
Physical Conditions ◽  
Dynamic Phenomena

It is well-known that solar activity is basically caused by the Interaction of magnetic fields with convection and solar rotation, resulting in a great variety of dynamic phenomena, like flares, surges, sunspots, prominences, etc. Many conferences have been devoted to solar activity, including the role of magnetic fields. Similar attention has not been paid to the role of magnetic fields for the overall dynamics and energy balance of the solar atmosphere, related to the general problem of chromospheric and coronal heating. To penetrate this problem we have to focus our attention more on the physical conditions in the ‘quiet’ regions than on the conspicuous phenomena in active regions.

INTERACTION OF THE NATIONAL ECONOMY OF UKRAINE WITH INTERNATIONAL CREDIT AND FINANCIAL ORGANIZATIONS

2017 ◽  
Author(s):  
Serhii Voitko ◽  
◽  
Yuliia Borodinova ◽  
Keyword(s):  
Financial Institutions ◽  
National Economy ◽  
Financial Support ◽  
Global Economy ◽  
Financial Sector ◽  
Negative Consequences ◽  
International Financial Institutions ◽  
The Future ◽  
International Credit

The article examines the interaction of the national economy of Ukraine with international credit and financial organizations, evaluates the positive and negative consequences and identifies possible areas for further cooperation. The role of international credit and financial organizations in the development of the global economy is analyzed. Today, international financial institutions have taken a leading place among institutions that provide financial support and contribute to the implementation of necessary reforms aimed at developing enterprises in various sectors of the economy and strengthening the country's financial sector as a whole. The importance of cooperation between Ukraine and international financial institutions for the development of the country's economy has been determined. The problems and directions of development of cooperation with leading credit and financial organizations in modern conditions are identified. Despite the presence of certain shortcomings, cooperation between Ukraine and international credit and financial organizations will continue in the future.

Physical Warmth Attenuates Ethnocentric Bias under Mortality Salience: An Embodied Terror Management Perspective

2020 ◽  
Author(s):  
Armand Chatard ◽  
Margaux Renoux ◽  
Jean Monéger ◽  
Leila Selimbegovic
Keyword(s):  
Mortality Salience ◽  
Terror Management ◽  
Negative Consequences ◽  
Defensive Reaction ◽  
Worldview Defense ◽  
Management Perspective ◽  
Physical Warmth ◽  
Alternative Means ◽  
First Time

Research indicates that individuals often deal with mortality salience by affirming beliefs in national or cultural superiority (worldview defense). Because worldview defense may be associated with negative consequences (discrimination), it is important to identify alternative means to deal with death-related thoughts. In line with an embodied terror management perspective, we evaluate for the first time the role of physical warmth in reducing defensive reaction to mortality salience. We predicted that, like social affiliation (social warmth), physical warmth could reduce worldview defense when mortality is salient. In this exploratory (preregistered) study, 202 French participants were primed with death-related thoughts, or an aversive control topic, in a heated room or a non-heated room. The main outcome was worldview defense (ethnocentric bias). We found no main effect of mortality salience on worldview defense. However, physical warmth reduced worldview defense when mortality was salient. Implications for an embodied terror management perspective are discussed.

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