Large-scale mining operations over 90 years at the Khibiny apatite-nepheline deposits that are characterized with the conspicuous gravity-tectonic type of the stress-strain state have transformed the initial stress field of the rock massif, which has led to the recurrent occurrence of rockbursts. This problem retains its relevance due to constant increasing intensity of mining operations at the apatite mines during the last two decades and complicated mining, geological and geomechanical conditions. Accordingly, the dynamic rock pressure is increasing. We have retrospectively analyzed data on the manifestations of geodynamic events in the Khibiny rockburst-hazardous deposits and determined a set of factors that influence the changes in seismic behavior and localization of hazardous zones in complicated mining and engineering systems. We have systematized the data of long-term observations on dynamic rock pressure manifestations at the Khibiny apatite mines, taking into account the seismicity parameters, the scale of mine damage, the mining-induced stress fields, and geological and geomechanical features of the rock massif at specific time points. A structural scheme has been developed and ranking of factors has been carried out, considering the time of impact on the rock massif.

This paper reports on the study of the effect of ion cleaning of emitting cleaved facet of 9xx nm laser diodes based on InGaAs/AlGaAs/GaAs on their limiting radiation power. Measured maximal power and the percentage of laser diodes with a visual manifestation of catastrophic optical damage in the active region were analyzed. It was found that short-term (1 min) low-energy treatment with argon and hydrogen ions does not lead to changes in the parameters of laser diodes, while treatment with nitrogen ions results in a decrease in the maximal output power and an increase in the probability of catastrophic optical damage. It is also shown that the use of an ion source based on electron cyclotron resonance leads to better results compared to a End Hall source or radiofrequency source with inductively coupled plasma, due to the lower energy of the ions.

The paper analyzes the dynamics of seismicity in the vicinity of the Saamy fault, Khibiny Massif, Kola Peninsula. The qualitative recording of seismic events has been carried out there since 2008. The study area is characterized as rockburst-hazardous and complicated by a geological fault, is developed by open pit mining, and includes the Kukisvumchorr and Yukspor deposits. In order to identify the influencing factors and mechanisms of rock mass failure, the authors used the spatial–temporal clustering of data, and analyzed the location and possible causes of the clusters. The areas with long-term seismic activity near the fault and the areas with short-term increase in seismic activity which is often induced by triggering factors are detected. The clusters in the console part of the rock mass are identified. At the Yukspor deposit, rock mass failed and caved into the Saamy open pit. It is found that opencast mining with blasting in the fault zone is a trigger for the fault activation, which is confirmed by seismic events recorded not only at the working level but also higher. The seasonal increase in water inflows is an additional factor in the fault activation; some clusters are characterized by a higher level of seismic activity during such periods. According to the authors’ conclusion, the analysis of seismicity on the basis of spatial and temporal data clustering allows timely revealing of seismic activation causes and enables necessary preventive measures (rock mass destressing, sectional breaking, bulk blasting to reduce stress level, etc.), which in general reduce the risks of man-induced catastrophes.

—The issues of the causes and factors of manifestation of seismic activity during the extraction of minerals in the deposits of the Khibiny massif, which are mined underground, are considered. Based on seismic monitoring data, groups of seismic activity were identified, such as seismicity in the working area, directly related to blasting and natural seismicity, related to other mining and geological factors. The difference in the characteristics of the manifestation of seismicity for these two groups of seismic events is shown.

A short-lived but violent explosive eruption occurred on the small volcanic island Raikoke in June 2019 (central Kuril Islands). The culmination of the eruption lasted 3.5 h and the ash cloud rose to a height of 13 km. An analysis of a sequence of satellite images in combination with ground-based observations gave information on the pyroclastic deposits of the eruption and allowed us to estimate the associated impact on the island ecosystems. We found that this eruption had a phreatomagmatic, sub-Plinian to Plinian character. The phreatomagmatic mechanism of the eruption occurred due to interaction between the rising basaltic andesite magma and ground waters, which were mostly represented by sea water that percolated through the permeable rocks of the volcanic island. The eruption produced numerous pyroclastic flows. The hot deposits of the pyroclastic flows and tephra covered the entire island, destroying the vegetation and the habitat of birds and sea mammals. Much of the pyroclasts was deposited in the form of fans of pyroclastic flows at the base of the volcanic slopes, considerably displacing the shoreline seaward. As a result, the island area increased by 15%. The pyroclastic deposits were intensely eroded and redeposited during the first year after the eruption, making new areas of the island coast. The recovery of Raikoke’s ecosystems will be enhanced by erosion of the pyroclastic deposits and gradual resettling of birds, which would bring new plant species to the island. The succession would be accelerated by areas of survived vegetation. Overall, we see periodic dramatic disruptions in the island ecosystems caused by violent explosive eruptions with subsequent rapid recovery that with high probability will be interrupted by new eruption.

Approaches to improve the L- I characteristics of laser diodes emitting at 940–980 nm based on InGaAs/AlGaAs/GaAs separate confinement double heterostructures with an asymmetric broadened waveguide are studied. The influence of the waveguide composition on the lasers output characteristics is analyzed. It is shown that a decrease in the energy depth of the QW leads to a decrease in series and thermal resistances and cut-off voltage that allows to improve output characteristics.

The purpose of this work is to improve the current – voltage ( I – V ) performance of semiconductor lasers based on broadened asymmetric waveguide InGaAs/AlGaAs/GaAs separate-confinement double heterostructures. We analyse the effect of AlGaAs waveguide layer composition on the output characteristics of the lasers and demonstrate that the decrease in the series resistance of the lasers and the threshold voltage of their I – V characteristic as a result of a decrease in the percentage of AlAs in the waveguide layers shifts the drop in the differential quantum efficiency of the lasers to higher pump currents, despite the decrease in the energy depth of the quantum wells in the active region.

Методика предназначена для определения склонности скальных горных пород к разрушениям в динамической форме по результатам испытаний образцов в условиях одноосного сжатия на стандартных прессах в соответствии с действующими в Российской Федерации стандартами и без установления запредельных характеристик. Приведены общие положения, метод отбора проб, оборудование и инструменты для проведения испытаний. Описаны процедуры подготовки к испытаниям и непосредственно самих испытаний, а также обработки результатов и определения склонности скальных пород к динамическим разрушениям.

Modern imaging technologies, including optoacoustic endoscopy, are based on the optoacoustic effect. Much promise is offered by the all-optical fiber-based approach, because fiber has a miniature cross section, is highly sensitive, and can be used in a variety of imaging and therapeutic techniques. We developed a probe based on a hollow-core microstructured optical waveguide (HC-MOW) with a hybrid nanostructured membrane. The membrane consisted of a free-standing single-walled carbon nanotube film and a Bragg reflector, which can be used as a source and a detector of ultrasound. Membrane vibrations were excited with an IR laser pulse and were read out by recording the intensity of the reflected visible CW laser light. We explained the nature of the intensity modulation of the reflected light and supported our explanation with numerical simulations of the membrane's vibration eigenfrequencies and thermal distribution. The membrane vibrations were also observed with raster-scanning optoacoustic mesoscopy. The transmittance of the HC-MOW between 400 nm and 6.5 mu m and that of the hybrid nanostructured membrane in the NIR range enable potential optoacoustic sensing in the IR fingerprint region of biomolecules. This permits the optoacoustic probe to be used for medical endoscopic purposes.

The paper presents a study of seismicity in the Khibiny massif and reviews development stages of seismic monitoring system and methods for predicting seismic hazard.A brief review of earthquakes in the Khibiny massif, which occurred from the beginning of the development of apatite-nepheline deposits to the present day, is given.The largest earthquake of magnitude 4.2 occurred on April 16, 1989 at the Kukisvumchorr deposit.The paper describes the main stages of seismic monitoring system development for mines in the Khibiny massif in operation by Apatit JSC, and the importance of the Mining Institute of the Kola Science Center, RAS in the formation of this system are given.The monitoring system was first introduced in Kirovsk mine (Kukisvumchorr and Yukspor deposits) and later in Rasvumchorr mine.These seismic monitoring systems have become one of the most important tools of the Rockburst Prediction and Prevention Service of Apatit JSC.They allow monitoring the state of rock mass in real time.This significantly increases safety of mining operations both in terms of operational decision-making and mid-term and long-term preventive measures.The authors studied the features of seismic activity during mining operations.The basics of two prediction techniques are presented.These techniques are the regional prediction of rockburst hazard using continuous monitoring of seismicity and the modern probabilistic approach to seismic hazard assessment.The results of the probabilistic approach to the seismic hazard assessment prove efficiency of the proposed methodology which can be used in the interpretation of seismic monitoring data.

В монографии отражены результаты аналитических и экспериментальных исследований закономерностей геомеханических процессов в геологической среде горнотехнических систем. Предложены объяснительные модели эволюции энергии в геологической среде в процессе ведения горных работ, показаны механизмы деформирования и разрушения пород в массиве с различными параметрами трещиноватости.Численным моделированием показана трансформация напряженного состояния массива пород,а также взаимодействие открытых и подземных технологий на примере Хибинских апатит-нефелиновых месторождений. Достаточно подробно изложена методика геомеханического мониторинга геологической среды в горнотехнических системах, включающая в себя геодинамическое районирование, инструментальные определения параметров напряженного состояния пород в массиве, контроль деформаций методами традиционной и спутниковой геодезии, регистрацию сейсмической эмиссии в широком частотном диапозоне. Разработана методология управления геодинамическими рисками при ведении горных работ в высоконапряженных массивах скальных пород, основанная на прогнозе и профилактике кризисной области, опасной по геодинамическим проявлениям горного давления, приведены примеры управления стратегическими, тактическими и оперативными рисками. Монография может быть полезной специалистам по геомеханике и геофизике, сотрудникам научно-исследовательских и проектных организаций, инженерно-техническим работникам горнорудных предприятий,а также студентам старших курсов и аспирантам горных,инженерно-геологических и строительных специальностей.

It is shown that it is promising to use the RGB data of bright-field optical microscopy to efficiently monitor the surface cleanliness of the active elements of semiconductor wafers in the planar production cycle. It is demonstrated that the film thickness on a substrate surface can be determined from RGB data obtained by means of a photosensor based on a Bayer array with known spectral response. An example shows how to use it on a GaAs semiconductor wafer with metallized active gold elements. Software has been developed for channel-by-channel comparison of a discriminated region of two pictures. An algorithm is presented for obtaining micrographs that can subsequently be analyzed and compared. (C) 2020 Optical Society of America

The effect of argon in a mixture with oxygen in an ion beam on the optical characteristics of titanium dioxide (TiO2) obtained via ion-assisted electron beam evaporation in vacuum was studied. It was shown that the addition of an inert gas at a level of 20%–25% resulted in an increase in the refractive index of the resulting TiO2 coating and a decrease in the sensitivity of the spectral characteristic of the coating to the effect of the atmosphere as a result of the decrease in the film porosity. The maximum amount of argon in the mixture was determined, amounting to 26%, at which the TiO2 film had an extinction coefficient not exceeding k=0.0001.