scholarly journals Development of a method for determining the stability reserve of iron ore pit board section

2021 ◽  
Vol 64 ◽  
pp. 68-80
Author(s):  
V Sidorenko ◽  
A Romanenko ◽  
V Panchenko
Keyword(s):  
Fractal Dimension ◽  
Iron Ore ◽  
Classical Method ◽  
Stability Margin ◽  
Computer Processing ◽  
Rock Fractures ◽  
Last Stage ◽  
The Stability ◽  
First Time ◽  
The Relationship

The purpose of this article is to develop a new methodology for assessing the stability margin of iron ore opencast sides sections. The sequence of work. To achieve this goal, at the first stage, high-resolution photography was carried out for characteristic sections of the pit wall, followed by computer processing of photographs to assess the fracturing of rocks. The next step was the calculation of the fractal dimension of the array section from the obtained images using the ImageJ and FracLac programs, including the MicroMod2015 plug-in package (add-ons). The next step was assess the disturbance of the massif due to fracturing, a study of the relationship between the fractal dimension and the coefficient of structural weakening was carried out (this coefficient is determined by the classical method through the ratio of the strength of rocks in the massif and in the sample). At the last stage of the work, after establishing the specified connection and calculating the coefficient of structural weakening of rocks that based on the results of determining the fractal dimension, an assessment of the stability margin iron ore opencast sides sections that carried out. The known dependence of the stability safety factor on the coefficient of structural weakening of the array was used. As a result of comparing the fractal dimension of the exposed massif areas based on photographs with the calculation by classical methods, the discrepancy in the structural attenuation coefficient was 5-10%. This indicates a satisfactory convergence and allows the use of this express technique for assessing the fracturing of a section of a pit flank on the basis of fractal dimension. The scientific novelty of the results obtained - for the first time, the analytical dependence of the structural weakening coefficient of rocks on the fractal dimension of the massif cracks was established, which made it possible to simplify the procedure for its calculation. The practical significanceof the work lies in the creation of a new methodology for assessing the stability margin of an iron ore opencast side sections that the basis of rock fractures fractal analysis.

scholarly journals Description of the larva of Bromeliagrion rehni (Odonata: Coenagrionidae) with bionomic notes concerning its phytotelmic habitat in central Amazonas, Brazil

2008 ◽  
Vol 25 (3) ◽  
pp. 479-486 ◽  
Author(s):  
Sharlene R. da S. Torreias ◽  
Ulisses G. Neiss ◽  
Neusa Hamada ◽  
Ruth L. Ferreira-Keppler ◽  
Frederico A.A. Lencioni
Keyword(s):  
Rainy Season ◽  
Environmental Parameters ◽  
Dry Season ◽  
Stage Larva ◽  
Water Volume ◽  
Apical Region ◽  
Last Stage ◽  
First Time ◽  
The Relationship

The last-stage larva of Bromeliagrion rehni Garrison in De Marmels & Garrison, 2005 is described and illustrated and bionomics and habitat information on this species are provided. The study was conducted in the Reserva Florestal Adolpho Ducke, located near Manaus, state of Amazonas, Brazil.Twelve samplings were done between April, 2003 and April, 2005: six in the rainy season and six in the dry season. In each sampling month, 12 bromeliads (Guzmania brasiliensis Ule, 1907, Bromeliaceae) were collected, six of which were terrestrial and six epiphytic, yielding144 samples. A total of 75 specimens of B. rehni were collected. The relationship between larval B. rehni abundance and the measured environmental parameters (volume (ml), pH, season and stratum) was significant (ANCOVA, F = 5.296, d.f. = 130, p < 0.001). Larvae were most abundant in the rainy season (p < 0.01) and water volume was positively related to the abundance of B. rehni. Larvae of B. rehni can be distinguished from those of B. fernandezianum (the only species in the genus with described larvae) by the number of setae in the prementum and by the color of the apical region of the femur. The association of this species with phytotelmata of G. brasiliensis is reported here for the first time.

Walking Stability Analysis of Multi-Legged Crablike Robot over Slope

2013 ◽  
Vol 572 ◽  
pp. 636-639
Author(s):  
Xi Chen ◽  
Gang Wang
Keyword(s):  
Mathematical Model ◽  
Stability Analysis ◽  
Stability Criterion ◽  
Stability Margin ◽  
Static Stability ◽  
Matlab Simulation ◽  
And Performance ◽  
The Stability ◽  
The Mathematical Model ◽  
The Relationship

This paper deals with the walking stability analysis of a multi-legged crablike robot over slope using normalized energy stability margin (NESM) method in order to develop a common stabilization description method and achieve robust locomotion for the robot over rough terrains. The robot is simplified with its static stability being described by NESM. The mathematical model of static stability margin is built so as to carry out the simulation of walking stability over slope for the crablike robot that walks in double tetrapod gait. As a consequence, the relationship between stability margin and the height of the robots centroid, as well as its inclination relative to the ground is calculated by the stability criterion. The success and performance of the stability criterion proposed is verified through MATLAB simulation and real-world experiments using multi-legged crablike robot.

Identification of the Stability Margin Between Safe Operation and the Onset of Blade Flutter

2007 ◽  
Author(s):  
Tim Rice ◽  
David Bell ◽  
Gurnam Singh
Keyword(s):  
Steam Turbine ◽  
Stability Margin ◽  
Operating Conditions ◽  
High Mass ◽  
Modern Trend ◽  
Safe Operation ◽  
Blade Flutter ◽  
Last Stage ◽  
The Stability ◽  
Tip Shroud

The introduction of longer last stage blading in steam turbine power plant offers significant economic and environmental benefits. The modern trend, adopted by most leading steam turbine manufacturers, is to develop long last stage moving blades (LSMB) that feature a tip shroud. This brings benefits of improved performance due to better leakage control and increased mechanical stiffness. However, the benefits associated with the introduction of a tip shroud are accompanied by an increased risk of blade flutter at high mass flows. The shroud is interlocked during vibration, causing the first axial bending mode to carry an increased, out of phase, torsional component. It is shown that this change in mode shape, compared to a unshrouded LSMB, can lead to destabilising aerodynamic forces during vibration. At a sufficiently high mass flow, the destabilising unsteady aerodynamic work will exceed the damping provided by the mechanical bladed-disk system, and blade flutter will occur. Addressing the potential for flutter during design and development is difficult. Simple tests prove inadequate as they fail to reveal the proximity of flutter unless the catastrophic condition is encountered. A comprehensive product validation programme is presented, with the purpose of identifying the margin for safe operation in respect to blade flutter. Unsteady CFD predictions are utilised to identify the mechanisms responsible for the unstable aerodynamic condition, and the particular modes of vibration that are most at risk. Using this information, a directed experimental technique is applied to measure the combined aerodynamic and mechanical damping under operating conditions. Results are presented which demonstrate the identification of the aeroelastic stability margin for a new LSMB. The stability margin predicted from the measurements demonstrates a significant margin of safety.

Identification of the Stability Margin Between Safe Operation and the Onset of Blade Flutter

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Tim Rice ◽  
David Bell ◽  
Gurnam Singh
Keyword(s):  
Steam Turbine ◽  
Stability Margin ◽  
Operating Conditions ◽  
High Mass ◽  
Modern Trend ◽  
Safe Operation ◽  
Blade Flutter ◽  
Last Stage ◽  
The Stability ◽  
Tip Shroud

The introduction of longer last stage blading in steam turbine power plant offers significant economic and environmental benefits. The modern trend, adopted by most leading steam turbine manufacturers, is to develop long last stage moving blades (LSMBs) that feature a tip shroud. This brings benefits of improved performance due to better leakage control and increased mechanical stiffness. However, the benefits associated with the introduction of a tip shroud are accompanied by an increased risk of blade flutter at high mass flows. The shroud is interlocked during vibration, causing the first axial bending mode to carry an increased, out of phase, torsional component. It is shown that this change in mode shape, compared to an unshrouded LSMB, can lead to destabilizing aerodynamic forces during vibration. At a sufficiently high mass flow, the destabilizing unsteady aerodynamic work will exceed the damping provided by the mechanical bladed-disk system, and blade flutter will occur. Addressing the potential for flutter during design and development is difficult. Simple tests prove inadequate as they fail to reveal the proximity of flutter unless the catastrophic condition is encountered. A comprehensive product validation program is presented, with the purpose of identifying the margin for safe operation with respect to blade flutter. Unsteady computational fluid dynamics predictions are utilized to identify the mechanisms responsible for the unstable aerodynamic condition and the particular modes of vibration that are most at risk. Using this information, a directed experimental technique is applied to measure the combined aerodynamic and mechanical damping under operating conditions. Results that demonstrate the identification of the aeroelastic stability margin for a new LSMB are presented. The stability margin predicted from the measurements demonstrates a significant margin of safety.

scholarly journals Long-term retainment of some chromosomal inversions in a local population of Belgica antarctica Jacobs (Diptera, Chironomidae)

2021 ◽  
Vol 11 (1) ◽  
pp. 16-24
Author(s):  
Paraskeva Michailova ◽  
Julia Ilkova ◽  
Pavlo Kovalenko ◽  
Artem Dzhulai ◽  
Iryna Kozeretska
Keyword(s):  
Classical Method ◽  
Local Population ◽  
Preparation Technique ◽  
Squash Preparation ◽  
Belgica Antarctica ◽  
Chromosome Iii ◽  
The Stability ◽  
Chromosome I ◽  
First Time

Genome of antarctic endemic Belgica antarctica Jacobs has been sequenced. However, no set of inversion diagnostic markers has ever been assigned for the species. Using the classical method of polytene chromosome squash preparation, we found three heterozygous inversions located on the second (two heterozygous inversions) and third chromosomes (one heterozygous inversion) in the Belgica antarctica population of a cape of Wiencke Island, 500 m to SW from Port Lockroy. The chromosome set and chromosome variability did not differ from those described in the literature (Atchley and Davis 1979). Every salivary gland chromosome had its own markers by which it can be determined. However, we did not find a sex-linked inversion on chromosome III and heterozygous inversion on chromosome I, reported in earlier studies. For the first time, we observed a strong heterochromatin band in chromosome III at the telomere of one arm. Our data show not only the stability of the described inversions in the population but also the usefulness of the squash preparation technique in the studies of genetic variability of Belgica antarctica in present time.

The system of diagnostic indicators of effective fertility of gray forest soil

2017 ◽  
Vol 1 (92) ◽  
pp. 36-43
Author(s):  
I.M. Malinovskaya ◽  
N.A. Tkachenko
Keyword(s):  
Forest Soils ◽  
Ammonium Nitrogen ◽  
Significance Level ◽  
Number Of Microorganisms ◽  
Medium Level ◽  
The Stability ◽  
Level Of Significance ◽  
Taxonomic Groups ◽  
First Time ◽  
The Relationship

The analysis of the significance of correlations ties between the yield of winter wheat (2012), soybean (2013), spring wheat (2014), buckwheat (2015) and the under indicators of quantity of microorganisms of some of ecology-trophic, functional and taxonomic groups, their of physiological and biochemical activity, the indicators of intensity processes of mineralization, the phytotoxicity, the stability of microbial communities for the four of seasons of vegetations it was conducted. It is established that the effective fertility of grey forest soils significantly (r = 0,666-0,999) positively correlated with the quantity of ammonificators; with immobilization of mineral nitrogen, oligonitrophillouses, cellulose decompose; with of autochthonous microorganisms; with total number of microorganisms (r = 0,684); with total biological activity (r = 0,764); with probability of forming of colonies denitrification (PFC); with of pH of salt and pH of water; with capacity in soil of nitrogen, potassium, phosphorus, humus. The yield of agricultural crops negatively correlated significantly with the number melaninsyntezuvalnyh Micromycetes (r = - 0,665) and with their specific contents in the total number of micromycetes (r = - 0,673), with the indicators of phytotoxicity (r = - 0,648), with the hydrolytic acidity, with the total exchange acidity and content of mobile aluminium.Direct correlation of medium significance level (r = 0,333-0,665) is observed between the effective fertility of grey forest soils and a quantity denitrifications, pedotrofov, of polisaharidnay microorganisms, actinomycetes, micromycetes, mobilizers of mineral phosphates, acid-forming microorganisms, PFC nitrifiers, of autochthonous, of cellulose-decomposing bacteria, with humus mineralization activity (r = 0,564), the content of nitrate nitrogen and of ammonium nitrogen, the phosphorus degree of mobility. Feedback of medium level of significance observed between the yield and PFC olihotrofnosti, index of pedotrofnosti. The relationship between yield and coefficient of nitrogen mineralization by average multi-year data was insignificant (r = 0,090). For the first time shown that an effective fertility of gray forest soils correlated with stability of microbial groupings, which is described of the quantity of significancy of correlation ties between their components.

scholarly journals The gait planning of hexapod robot based on CPG with feedback

2020 ◽  
Vol 17 (3) ◽  
pp. 172988142093050 ◽  
Author(s):  
Binrui Wang ◽  
Ke Zhang ◽  
Xuefeng Yang ◽  
Xiaohong Cui
Keyword(s):  
Central Pattern Generator ◽  
Stability Margin ◽  
Pattern Generator ◽  
The Body ◽  
Middle Level ◽  
Point Problem ◽  
Vector Product ◽  
Hexapod Robot ◽  
The Stability ◽  
The Relationship

To realize the omnidirectional motion, the transition motion of hexapod robot from flat to slope is studied, and a new type of stability criterion is proposed. Firstly, the landing point problem of the hexapod robot in the process of transition is studied, the relationship between the introduced angle in ankle of the supporting leg and the body pitch is acquired, and the transition gait based on central pattern generator bottom feedback is planned. Secondly, the slope motion is analyzed, the relationship between the angle variable of the supporting knee joint and the pitch angle of hexapod is obtained, and the slope gait is planned based on central pattern generator middle level feedback. According to vector product, the solution of working out the stability margin of hexapod robot’s motion is designed. Lastly, MATLAB/ADAMAS co-simulation platform and physical hardware are constructed, the simulation and experiment of transition motion of hexapod robot from flat to 12° slope and motion of climbing 16° slope are done. According to the analysis of the results, in the transition motion from flat to 12° slope, based on the transition gait, hexapod robot can keep three foots touch the ground, and the foot force is uniform. According to the means designed to work out a stability margin based on vector product, the stability margin constant is greater than zero. In the motion of climbing 16° slope, based on the slope gait, hexapod robot completes the motion of climbing 16° slope. Based on transition gait, hexapod robot implements the transition movement from flat to slope stably. Based on slope gait, hexapod robot improves the ability of slope motion.

THE RELATIONSHIP BETWEEN WORKPLACE SPIRITUALITY AND JOB PERFORMANCE AMONG STAFF OF AZAD ISLAMIC UNIVERSITY, IRAN

2018 ◽  
Vol 6 (1) ◽  
pp. 14-18
Author(s):  
Narjes Khatun Tayebiniya ◽  
Narges Saeidian Khorasgani
Keyword(s):  
Job Performance ◽  
Social Relations ◽  
Meaningful Work ◽  
Workplace Spirituality ◽  
University Staff ◽  
Item Questionnaire ◽  
Research Population ◽  
The Stability ◽  
First Time ◽  
The Relationship

Purpose: This study aims at specifying the relationship between workplace spirituality and job performance among Isfahan Azad Islamic university's staff. Methodology: This study is descriptive correlational one conducted in 2015. Research population were all Isfahan Azad University staff, 375 individuals among the 189 ones were accidently and based on the mass of their department, and Cochran sample mass selected. Instruments used in this study were Ashmos (2000)'s 22-item questionnaire of workplace spirituality and Paterson's (1970) 15-item questionnaire of job performance. The stability of these questionnaires in Cronbach's Alpha was computed as 0.88 and 0.83 for workplace spirituality and job performance, respectively. Data extracted in this study was analyzed through multi-regression tests, Pierson correlation coefficient and SPSS software of variance analytical tests. Main Findings: The results of this study show that there exists a meaningful relation between workplace spirituality (r=0.330), meaningful work (r=0.287), a sense of connection and positive social relations with coworkers (r=0. 298), individual's alignment with the organization's values (r=0.326) and job performance. (P=0.001) in the first step, from among these workplace spirituality dimensions, meaningful work is the best indicator of staff's job performance. Implications: This study and results can throw light on strategies to be adopted to enhance job performance in University staff. Originality: This type of study is done first time in University. 

scholarly journals Causality Relationship between Export and Economic Growth: The Case of Russia

2015 ◽  
Author(s):  
Özgür Uysal ◽  
Sultan Sat
Keyword(s):  
Economic Growth ◽  
Unit Root Test ◽  
Growth Data ◽  
Causality Test ◽  
Integration Test ◽  
Augmented Dickey Fuller ◽  
Last Stage ◽  
Causality Relationship ◽  
The Stability ◽  
The Relationship

Nowadays, together with the process of globalization, the relation between export and economic growth has begun to gain importance when decisions regarding economic situation of a country are taken, and when estimations concerning economy are made. The relation between economic growth and export has become one of the most disputable issues of the economic literature. The main objective of this study is to find out the direction of the relation between export and economic growth in Russia. Analysis was performed by using quarterly export and economic growth data of belonging from 1997:01 to 2014:04.The stability of the variables was initially determined by using Augmented Dickey – Fuller (ADF) unit root test. Subsequently, the existence of co-integration between variables was investigated by using Johansen Co–integration Test. In the last stage, the direction of the relationship between variables was determined by using Granger Causality Test. As a result of the analyses carried out, it was determined that bi-directional causality exists between export and economic growth in Russia between the years 1997-2014.

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