scholarly journals Increasing safety at rock preparation by blasting in open pits

2019 ◽  
Vol 134 ◽  
pp. 01017
Author(s):  
Igor Katanov ◽  
Sergey Kondratyev ◽  
Andrey Sysoyev
Keyword(s):  
Rock Mass ◽  
Explosive Charge ◽  
Integrated Approach ◽  
Variable Density ◽  
Low Density ◽  
Angle Of Incidence ◽  
Firing Time ◽  
High Quality ◽  
Minimal Deviation ◽  
Electronic Detonator

The topicality of the present work lies in justification of the means of increasing safety during mass explosions in opencasts. The solution to this problem is possible due to the orientation of downholes in the array, taking into account the angle of incidence and extension of the strata, high-quality stemming and initiation of downhole charges by delay detonators with a minimal deviation from nominal values of their firing time. The most promising way to increase the safety and efficiency of blasting is an integrated approach, including drilling downholes, normal to the strata, and using the design of the downhole charge, rationally distributing the explosion energy in the space of the rock mass due to the use of stemming of a variable density, low-density gap between the parts of the explosive charge and the bottom a downhole compensator based on foam gel and the use of hybrid electronic detonator Iskra-T.

Quantitative defect studies in semiconductor TEM samples prepared by low angle ion milling

1995 ◽  
Vol 53 ◽  
pp. 512-513
Author(s):  
L. Mulestagno ◽  
J.C. Holzer ◽  
P. Fraundorf
Keyword(s):  
Sample Preparation ◽  
Milling Time ◽  
High Density ◽  
Low Density ◽  
Ion Milling ◽  
High Quality ◽  
Variable Angle ◽  
Major Disadvantage ◽  
Induced Defects

Due to the wealth of information, both analytical and structural that can be obtained from it TEM always has been a favorite tool for the analysis of process-induced defects in semiconductor wafers. The only major disadvantage has always been, that the volume under study in the TEM is relatively small, making it difficult to locate low density defects, and sample preparation is a somewhat lengthy procedure. This problem has been somewhat alleviated by the availability of efficient low angle milling.Using a PIPS® variable angle ion -mill, manufactured by Gatan, we have been consistently obtaining planar specimens with a high quality thin area in excess of 5 × 104 μm2 in about half an hour (milling time), which has made it possible to locate defects at lower densities, or, for defects of relatively high density, obtain information which is statistically more significant (table 1).

scholarly journals Incompressible variable-density turbulence in an external acceleration field

2017 ◽  
Vol 827 ◽  
pp. 506-535 ◽  
Author(s):  
Ilana Gat ◽  
Georgios Matheou ◽  
Daniel Chung ◽  
Paul E. Dimotakis
Keyword(s):  
Growth Rate ◽  
Turbulent Flow ◽  
Shear Layers ◽  
Variable Density ◽  
Fluid Composition ◽  
Turbulent Regime ◽  
Low Density ◽  
Acceleration Field ◽  
Density Ratios ◽  
Mixed Fluid

Dynamics and mixing of a variable-density turbulent flow subject to an externally imposed acceleration field in the zero-Mach-number limit are studied in a series of direct numerical simulations. The flow configuration studied consists of alternating slabs of high- and low-density fluid in a triply periodic domain. Density ratios in the range of $1.05\leqslant R\equiv \unicode[STIX]{x1D70C}_{1}/\unicode[STIX]{x1D70C}_{2}\leqslant 10$ are investigated. The flow produces temporally evolving shear layers. A perpendicular density–pressure gradient is maintained in the mean as the flow evolves, with multi-scale baroclinic torques generated in the turbulent flow that ensues. For all density ratios studied, the simulations attain Reynolds numbers at the beginning of the fully developed turbulence regime. An empirical relation for the convection velocity predicts the observed entrainment-ratio and dominant mixed-fluid composition statistics. Two mixing-layer temporal evolution regimes are identified: an initial diffusion-dominated regime with a growth rate ${\sim}t^{1/2}$ followed by a turbulence-dominated regime with a growth rate ${\sim}t^{3}$. In the turbulent regime, composition probability density functions within the shear layers exhibit a slightly tilted (‘non-marching’) hump, corresponding to the most probable mole fraction. The shear layers preferentially entrain low-density fluid by volume at all density ratios, which is reflected in the mixed-fluid composition.

Fundamental Study of the Temperature Ramp-Up Influence for 3C-SiC Hetero-Epitaxy on Silicon (100)

2010 ◽  
Vol 645-648 ◽  
pp. 151-154 ◽  
Author(s):  
Philip Hens ◽  
Günter Wagner ◽  
Astrid Hölzing ◽  
Rainer Hock ◽  
Peter J. Wellmann
Keyword(s):  
Nucleation Rate ◽  
Carbon Layer ◽  
Low Density ◽  
High Quality ◽  
Fundamental Study ◽  
Temperature Range ◽  
Peak Intensity ◽  
Temperature Ramp ◽  
Domain Boundaries

Usually a waiting step at around 1000°C to 1100°C during the carbonization step for 3C-SiC on silicon is implemented for establishing a closed carbon layer to prevent the formation of voids. The latter, however, may lead to non-ideal nucleation conditions for high quality layers with a low density of domain boundaries. Our investigations indicate that a continuous ramp-up as fast as possible with no waiting step would be preferable. The worst layer quality, as measured by peak intensity and FWHM of the (200) reflection of 3C SiC, can be found at a temperature of about 1000°C, which indicates that here the nucleation rate would be the highest. So longer periods within this temperature range should be avoided by applying high ramping speeds during the carbonization step.

Pre-Programmed Failure Behavior Using Biology-Inspired Structures

2007 ◽  
Author(s):  
Brian Bay ◽  
Mike Bailey
Keyword(s):  
Failure Modes ◽  
Variable Density ◽  
Failure Behavior ◽  
Filler Materials ◽  
Low Density ◽  
Low Velocity ◽  
Working Stress ◽  
Component Strength ◽  
Box Beams ◽  
Increasing Demand

Core (filler) materials are key components of the sandwich panel and box-beams that are used in the design of lightweight structures. They perform a variety of elastic-range functions such as transferring and supporting working stresses and energy and collapse management. There is an increasing demand, however, for post-yield performance characteristics such as buckling control, impact toughness, and maintenance of component strength after damage. Low density is also an important consideration, as overall component mass is critical in most applications. These cellular solids need to perform well under normal working stress conditions, yet still resist damage from simple and unavoidable low velocity impacts. A new design approach is suggested by biological systems that have evolved for toughness and damage tolerance (bones, trees, plants, corals, etc.). These systems share the relatively low density cellular arrangements of common synthetic core materials, but also exhibit variable density gradients within the core. (Figures 1 and 2) This paper describes engineering design methods that are inspired by such biology. The result is that a design’s failure modes can be more effectively “designed-in”, controlling locations and amounts of failure.

Control of Iron Disilicide Crystal Structure by Using Liquid Phase Obtained by Au-Si Eutectic Reaction

2015 ◽  
Vol 1760 ◽  
Author(s):  
Kensuke Akiyama ◽  
Yuu Motoizumi ◽  
Hiroshi Funakubo
Keyword(s):  
Liquid Phase ◽  
Photoluminescence Spectrum ◽  
Radiative Recombination ◽  
Single Phase ◽  
Eutectic Reaction ◽  
Substrate Surface ◽  
Low Density ◽  
Si Substrate ◽  
High Quality ◽  
Iron Disilicide

ABSTRACTThe Au-Si liquid phase was obtained by melting the Si surface via Au-Si eutectic reaction, which contributed to the formation of semiconducting iron disilicide (β-FeSi2), on Au-coated Si(100) substrates. By coating a substrate with an Au layer of 60 nm or more, the Au-Si liquid phase covered the entire Si substrate surface, and single-phase β-FeSi2 was grown on Si(100) substrates. A clear photoluminescence spectrum of β-FeSi2 indicated the formation of high-quality crystals with a low density of the non-radiative recombination center in the grains.

scholarly journals Improving the efficiency of tunneling underground mine workings with the use of blasthole charges with Munroe effect

2020 ◽  
pp. 15-23
Author(s):  
Farkhodbek Umarov ◽  
◽  
Utkir Nasirov ◽  
Gafur Nutfulloev ◽  
Zoir Nazarov ◽  
...  
Keyword(s):  
Rock Mass ◽  
Explosive Charge ◽  
Underground Mine ◽  
Theoretical Research ◽  
Hydrodynamic Theory ◽  
Energy Concentration ◽  
Face Advance ◽  
Efficiency Ratio ◽  
Underground Mine Workings ◽  
Mine Workings

Introduction. Various techniques of breaking rock by explosion have currently been developed when tunneling underground mine workings, but asymmetrically directed stress fields application is of the main interest. Research aim is to study explosion energy distribution and maximum concentration deep down the blasted rock mass. Blast energy concentration may be achieved by using the principle of cumulation in the hole back by means of changing the design of the blasthole explosive charge. Methodology. Based on the analyzed literature and theoretical research it is recommended to use the design of a blasthole explosive charge with the use of Munroe effect, which makes it possible to increase the blasthole efficiency ratio (BER), reduce drilling activity, reach sharper design contours of mine workings and eliminate bootlegs. The action of blasthole explosive charges with Munroe effect has been theoretically investigated, hydrodynamic theory of cumulation has been studied, and the dependences have been determined between the liner’s collapsing angle alternation and the radius of the cone, its height, initial velocity, and cumulative jet velocity. Results. The main factors which determine the efficiency of the proposed new technique of blasting against the basic technique are the blasthole efficiency ratio, face advance pace after one blast, the amount of rock mass detached after one blast, and the granulometric composition of the blasted rock mass. Summary. The developed design of the blasthole explosive charge with Munroe effect makes it possible to increase BER, face advance per one cycle, and increase the amount of the broken rock mass.

scholarly journals Domestic and foreign experience in the application of methods and technologies of selection for police service

2021 ◽  
pp. 118-126
Author(s):  
Иван Васильевич Краснов
Keyword(s):  
Personal Characteristics ◽  
Integrated Approach ◽  
Professional Activity ◽  
High Quality ◽  
Police Service ◽  
Foreign Experience ◽  
Private Organizations ◽  
Future Activity ◽  
Selection For ◽  
Selection Of

В статье рассмотрена проблема качественного подбора и отбора кандидатов на службу в территориальные органы (подразделения) Росгвардии. Психологический отбор, вместе с его психофизиологической составляющей, представляет собой часть профессионального отбора, направленный на выявление таких сотрудников, которые по своим моральным, психофизиологическим и психологическим качествам, наиболее соответствуют конкретным требованиям будущей деятельности. В то же время высокоэффективный психологический отбор должен иметь комплексный подход, который соответствует двум принципам, первый – это принцип дифференцированности и динамичности, второй – надежность и прогностичность применяемых методик. Рассмотрен опыт применения полиграфа в полиции в ходе кадровой работы. Представлены результаты изучения кандидатов на работу в частные организации и на службу в Росгвардию. Профессиональный психологический отбор также рассматривается как комплекс мероприятий, направленных на обеспечение качественного отбора персонала организации на основе оценки соответствия уровня развития необходимых психофизиологических (индивидных) качеств и свойств личности требованиям профессиональной деятельности. Обобщены социально-психологические и личностные характеристики кандидатов, выявляемые в процессе психодиагностических исследований и негативно влияющие на прохождение ими дальнейшей службы. The article considers the problem of qualitative selection and selection of candidates for service in the territorial bodies (divisions) of the Rosgvardiya. Psychological selection, together with its psychophysiological component, is a part of professional selection aimed at identifying such employees who, according to their moral, psychophysiological and psychological qualities, most correspond to the specific requirements of future activity. At the same time, highly effective psychological selection should have an integrated approach that corresponds to two principles, the first is the principle of differentiation and dynamism, the second is the reliability and prognosticality of the methods used. The experience of using a polygraph in the police in the course of personnel work is considered. The results of the study of candidates for work in private organizations and for service in the Rosgvardiya are presented. Professional psychological selection is also considered as a set of measures aimed at ensuring a high-quality selection of the organization's personnel based on an assessment of the compliance of the level of development of the necessary psychophysiological (individual) qualities and personality properties with the requirements of professional activity. The socio-psychological and personal characteristics of candidates identified in the process of psychodiagnostic research and negatively affecting their further service are summarized.

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