Improving the efficiency of blasting operations in mines with the help of emulsion explosives

Purpose. To improve the efficiency of blasting operations in mines taking into consideration the upgrading of equipment used to charge blastholes as well as application of high-productive mining equipment of new generation. Methods. The activities used mine experimental pressure-charged blasts to break oversize material as well as mine experimental analysis of blasthole charging to estimate the improvement of efficiency of the emulsion explosives (EEs). Findings. It has сbeen determined that both sticked and bulk emulsion explosives of Ukrainit-PP-2 type as well as new options of charging facilities have following technological characteristics: availability of unique space-saving designs of two-component piston dosing pumps of double-action EE components; sufficiently high efficiency of blasthole charging being up to 60 kg of EE/min; ease of service and maintenance; rather long overhaul period of EE components as for the dosing pump as well as cheapness of attachable equipment; availability of both electronic and visual means to control EE preparation and charging. Originality. It has been proved that the improvement of blasting operations in mines results from the intensified technological processes of blasthole charging characterized by the use of such high-productive self-propelled and space-saving facilities of new generation as machines of ZEVS-1 model and portable charges of ZEP-15 type as well as the use of such environmentally friendly bulk trinitrotoluene-free emulsion explosives as Ukrainit-PP-2. Practical implications. Use of EEs in the process of mine blasting operations provides safety, high-quality rock breakage and fragmentation in the context of minimum toxicity of rock, breakage of rocks having any hardness and water content. Moreover, their use is economically efficient.Мета. Підвищення ефективності виконання вибухових робіт за допомогою емульсійних вибухових речовин на шахтах з урахуванням вдосконалення обладнання для заряджання вибухових свердловин, а також застосування високопродуктивної гірничої техніки нового покоління. Методика. В роботі для оцінки підвищення ефективності виробництва вибухових робіт за допомогою емульсійних вибухових речовин на шахтах використані шахтні експериментальні вибухи накладного заряду при руйнуванні негабариту й шахтні експериментальні дослідження процесу заряджання шпурів. Результати. Встановлено, що патроновані та наливні емульсійні вибухові речовини (ЕВР) типу Україніт-ПП-2 і нові варіанти зарядних машин мають наступні технологічні особливості: наявність у своєму складі оригінальних малогабаритних конструкцій двокомпонентних поршневих насосів-дозаторів компонентів ЕВР подвійної дії; досить високу продуктивність заряджання свердловин – до 60 кг ЕВР/хв; простоту в обслуговуванні та ремонтах; досить високе напрацювання до капремонту насосу-дозатора компонентів ЕВР, а також значно меншу вартість навісного обладнання; наявність як електронних, так і візуальних засобів контролю за приготуванням і заряджанням ЕВР. Наукова новизна. Доведено, що підвищення ефективності виробництва вибухових робіт на шахтах досягається інтенсифікацією технологічних процесів заряджання вибухових свердловин, що відрізняються застосуванням високопродуктивної самохідної та малогабаритної техніки нового покоління, таких як машини моделі ЗЕВС-1 і переносні зарядники моделі ЗЕП-15 та використанням наливних, екологічно чистих, безтротилових ЕВР Україніт-ПП-2. Практична значимість. Застосування ЕВР на шахтах при веденні вибухових робіт забезпечує без-небезпечне ведення робіт, високу якість відбійки і дроблення гірських порід при мінімальній токсичності, руйнування гірської породи будь-якої міцності й обводненості та економічну ефективність.Цель. Повышение эффективности производства взрывных работ с помощью эмульсионных взрывчатых веществ на шахтах с учетом совершенствования оборудования для заряжания взрывных скважин, а также применения высокопроизводительной горной техники нового поколения. Методика. В работе для оценки повышения эффективности производства взрывных работ с помощью эмульсионных взрывчатых веществ на шахтах использовались шахтные экспериментальные взрывы накладного заряда при разрушении негабарита и шахтные экспериментальные исследования процесса заряжания шпуров. Результаты. Установлено, что патронированные и наливные эмульсионных взрывчатых веществ (ЭВВ) типа Украинит-ПП-2 и новые варианты зарядных машин имеют следующие технологические особенности: наличие в своем составе оригинальных малогабаритных конструкций двухкомпонентных поршневых насосов-дозаторов компонентов ЭВВ двойного действия; достаточно высокую производительность заряжания скважин – до 60 кг ЭВВ/мин; простоту в обслуживании и ремонтах, достаточно высокую наработку до капремонта по насосу-дозатору компонентов ЭВВ, а также значительно меньшую стоимость навесного оборудования; наличие как электронных, так и визуальных средств контроля за приготовлением и заряжанием ЭВВ. Научная новизна. Доказано, что повышение эффективности производства взрывных работ на шахтах достигается интенсификацией технологических процессов заряжания взрывных скважин, отличающихся применением высокопроизводительной самоходной и малогабаритной техники нового поколения, таких как машины модели ЗЭВС-1 и переносные зарядчики модели ЗЭП-15 и использованием наливных, экологически чистых, бестротиловых ЭВВ Украинит-ПП-2. Практическая значимость. Применение ЭВВ на шахтах при ведении взрывных работ обеспечивает безопасное ведение работ, высокое качество отбойки и дробления горных пород при минимальной токсичности, разрушение горной породы любой степени крепости и обводненности и экономическую эффективность.The studies have been carried out according to the materials of the report with the participation of the authors in 15th International Conference Resource-generative, low-waste, and nature-protective technologies of mineral development (Vorob’yev, Lyashenko, & Nebogin, 2015) in association with such experts as P.A. Kysly, N.N. Shvets, V.S. Cherevyk, A.I. Lytvyn (A and M SIC), V.I. Boiko, A.S. Karaban, M.B. Kolesaiev, V.V. Shkaryn (LLC “NTO Tekhnotron”) and others

Integrated effect of atmosphere pollution and cutting on seed production of dandelion (Taraxacum officinale Wigg.) urban populations

© 2016, International Journal of Pharmacy and Technology. All rights reserved.We considered the influence of air pollution by road transport on the total number of seeds, seed weight and the formation of seeds able to germinate in the inflorescences of Taraxacum officinale Wigg cut off on the fourth day after flowering, and in the inflorescences formed on the parent plant. The monotonous dependence dose-response is characteristic for the seeds developed on the parent plant. The dependencies of other seed production indicators from air pollution intensity by motor traffic are nonmonotonic ones, which can be attributed to the paradoxical effects that appear brighter in the inflorescences cut off on the fourth day after flowering. The intensity of seed germination, formed on the mother plant, is also difficult and depends nonmonotonically on the degree of atmosphere contamination, but the seeds with the weight less than 0.25 mg are not developed. A significant influence on the relationship between the weight of seeds and their germination is made by negative impact factor duration. At the same weight (0,39 ± 0,02 mg) the maximum germination of the option “cut off florets” and a minimum one for the version “ripened on parent plant”. At the same time a lot of seeds correlated with their germination differently. For the seeds ripened in the cut off inflorescences R2 = 0.80 (p = 0.00027), and for the seeds ripened on the parent plant R2 = 0.55 (p = 0.008). The critical mass of viable seeds for their germination in cut off inflorescences made 0.23 ± 0.007 mg, which is 10% more than a certain critical mass of Taraxacum officinale seeds stated earlier

Spin orientation of a two-dimensional electron gas by a high-frequency electric field

Coupling of spin states and space motion of conduction electrons due to spin-orbit interaction opens up possibilities for manipulation of the electron spins by electrical means. It is shown here that spin orientation of a two-dimensional electron gas can be achieved by excitation of the carriers with a linearly polarized high-frequency electric field. In (001)-grown quantum well structures excitation with in-plane ac electric field induces orientation of the electron spins along the quantum well normal, with the spin sign and the magnitude depending on the field polarization.Comment: 5 pages, 1 figur

DFT-based calculations of silicon complex structures in KF–KCl–K2SiF6 and KF–KCl–K2SiF6–SiO2 melts

The length and energy of bonds in the complex anions of silicon formed in KF−KCl−K2SiF6 and KF−KCl−K2SiF6–SiO2 melts were evaluated using the method of first-principles molecular dynamics, accomplished by means of the Siesta program. The effect of K+ (from the second coordination sphere) on the stability of these complexes was studied. The bond lengths in the silicon complexes was found to change with increasing amount of the potassium ions. It was established that the following complexes [SiO4]4-, [SiO3F]3- and [SiF6]2- are the most stable in KF−KCl−K2SiF6 and KF−KCl––K2SiF6–SiO2 melts. The [SiO4]4- and [SiF6]2- complexes are thermally stable in the molten salt in the temperature range of 923–1073 K, whereas the [SiF7]3-structure, which is typical for the lattice of crystalline K3SiF7, is unstable in this temperature range. In the KF−KCl−K2SiF6−SiO2 melts, conditions above 1043 K were created allowing the transformation of [SiО3F]3- into [SiO4]4-. Within the studied temperature mode, the Si–F bond length is in the range 1.5––1.9 Å and the Si–O bond lengths is 1.5–1.7 Å. The obtained results are in a good agreement with in situ data of Raman spectroscopy for the KF−KCl−K2SiF6 and KF–KCl–K2SiF6–SiO2 melts. © 2019 Serbian Chemical Society. All rights reserved.Russian Science Foundation, RSF: 18-73-00227The work was accomplished with the financial support of the Russian Science Foundation, Project No. 18-73-00227

First-principles study of spontaneous polarization in multiferroic BiFeO3_3

The ground-state structural and electronic properties of ferroelectric BiFeO$_3$ are calculated using density functional theory within the local spin-density approximation and the LSDA+U method. The crystal structure is computed to be rhombohedral with space group $R3c$, and the electronic structure is found to be insulating and antiferromagnetic, both in excellent agreement with available experiments. A large ferroelectric polarization of 90-100 $\mu$C/cm$^2$ is predicted, consistent with the large atomic displacements in the ferroelectric phase and with recent experimental reports, but differing by an order of magnitude from early experiments. One possible explanation is that the latter may have suffered from large leakage currents. However both past and contemporary measurements are shown to be consistent with the modern theory of polarization, suggesting that the range of reported polarizations may instead correspond to distinct switching paths in structural space. Modern measurements on well-characterized bulk samples are required to confirm this interpretation.Comment: (9 pages, 5 figures, 5 tables

Performance of the oil pipeline with the dangerous defects of cracks type in connection with the long-time operation

Випробування на циклічну тріщиностійкість зразків з труб лінійної частини нафтопроводу здійснювали на універсальній сервогідравліческой машині в таких умовах: кімнатна температура, частота 20 Гц і коефіцієнт асиметрії R = 0,1. Тріщина в зразках була орієнтована в осьовому й окружному напрямках для вивчення анізотропії властивостей. Кінетичну діаграму втомного руйнування і діаграму циклічного пружно-пластичного руйнування будували за результатами випробувань та вимірювання утяжки зразка. У статті наведено значення силових і деформаційних характеристик циклічної тріщиностійкості дослідженої сталі після тривалої експлуатації.The fatigue crack growth resistance tests of specimens made of the tube of line parts of an oil pipeline conducted on universal servo hydraulic testing machine under next conditions: room temperature, frequency of 20 Hz and stress ratio R= 0,1. Specimen’s crack is oriented in axial and circumferential directions for study of anisotropy properties. Fatigue crack growth diagram and the cyclic elasto-plastic fracture diagram are plotted by tests results and due to measuring of contraction. The values of force and deformation characteristics of a fatigue crack growth of investigated steel after long operation are given in paper

Origin of magnetoelectric behavior in BiFeO3_3

The magnetoelectric behavior of BiFeO$_3$ has been explored on the basis of accurate density functional calculations. The structural, electronic, magnetic, and ferroelectric properties of BiFeO$_3$ are predicted correctly without including strong correlation effect in the calculation. Moreover, the experimentally-observed elongation of cubic perovskite-like lattice along the [111] direction is correctly reproduced. At high pressure we predicted a pressure-induced structural transition and the total energy calculations at expanded lattice show two lower energy ferroelectric phases, closer in energy to the ground state phase. Band-structure calculations show that BiFeO$_3$ will be an insulator in A- and G-type antiferromagnetic phases and a metal in other magnetic configurations. Chemical bonding in BiFeO$_3$ has been analyzed using various tools and electron localization function analysis shows that stereochemically active lone-pair electrons at the Bi sites are responsible for displacements of the Bi atoms from the centro-symmetric to the noncentrosymmetric structure and hence the ferroelectricity. A large ferroelectric polarization (88.7 $\mu$C/cm$^{2}$) is predicted in accordance with recent experimental findings. The net polarization is found to mainly ($>$ 98%) originate from Bi atoms. Moreover the large scatter in experimentally reported polarization values is due to the large anisotropy in the spontaneous polarization.Comment: 19 pages, 12 figures, 4 table

Impurity breakdown and terahertz luminescence in n-GaN epilayers under external electric field

We report on the observation and experimental studies of impurity breakdown and terahertz luminescence in n-GaN epilayers under external electric field. The terahertz electroluminescence is observed in a wide range of doping levels (at noncompensated donor density from 4.5×10[sup 16] to 3.4×10[sup 18] cm[sup −3]). Spectra of terahertz luminescence and photoconductivity are studied by means of Fourier transform spectrometry. Distinctive features of the spectra can be assigned to intracenter electron transitions between excited and ground states of silicon and oxygen donors and to hot electron transitions to the donor states.Peer reviewe

Quantum Hall effect in a high-mobility two-dimensional electron gas on the surface of a cylinder

The quantum Hall effect is investigated in a high-mobility two-dimensional electron gas on the surface of a cylinder. The novel topology leads to a spatially varying filling factor along the current path. The resulting inhomogeneous current-density distribution gives rise to additional features in the magneto-transport, such as resistance asymmetry and modified longitudinal resistances. We experimentally demonstrate that the asymmetry relations satisfied in the integer filling factor regime are valid also in the transition regime to non-integer filling factors, thereby suggesting a more general form of these asymmetry relations. A model is developed based on the screening theory of the integer quantum Hall effect that allows the self-consistent calculation of the local electron density and thereby the local current density including the current along incompressible stripes. The model, which also includes the so-called `static skin effect' to account for the current density distribution in the compressible regions, is capable of explaining the main experimental observations. Due to the existence of an incompressible-compressible transition in the bulk, the system behaves always metal-like in contrast to the conventional Landauer-Buettiker description, in which the bulk remains completely insulating throughout the quantized Hall plateau regime

ИК-люминесценция CaGa2O4:Yb3+ при возбуждении излучением с длиной волны 940 и 980 нм

The article provides an overview of known luminescent materials based on calcium gallate CaGa2O4, emitting in the visible and infrared (IR) spectral regions. IR phosphors have not been studied much, but their practical application is of interest. The solid-phase method was used to obtain CaGa2O4 samples activated with rare-earth ions Yb3+. The structural and luminescent properties of the composition CaGa2O4 : Yb3+ were studied. When CaGa2O4 : Yb3+ was excited by radiation with a wavelength of 940 and 980 nm, luminescence was recorded in the range of 980—1100 nm. Based on data on the structure of electronic levels in Yb3+ ions, it is concluded that excitation and radiation occur directly in Yb3+ ions with the passive participation of the base lattice. Three maximums at a wavelength were recorded on the luminescence spectra: 993 nm, 1025 nm, 1080 nm. The radiation in these bands is due to optical transitions of electrons from the excited to the ground state in Yb3+ ions. The dependence of the luminescence intensity in the 993 nm band on the concentration of Yb3+ activator ions was studied. It found that the introduction of the phosphor ions Na+ increases the intensity of the infrared luminescence. An optimal composition of the phosphor (Ca1-x-yYbxNay)Ga2O4 is proposed, at which the luminescence intensity in the range of 980—1100 nm is maximum.Представлен обзор известных люминесцентных материалов на основе галлата кальция CaGa2O4, излучающих в видимой и инфракрасной (ИК) области спектра. На сегодняшний день ИК-люминофоры исследованы мало, но их практическое применение представляет интерес. Твердофазным методом получены образцы CaGa2O4, активированные редкоземельными ионами Yb3+. Исследованы структурные и люминесцентные свойства состава CaGa2O4 : Yb3+. При возбуждении CaGa2O4 : Yb3+ излучением с длиной волны 940 и 980 нм зарегистрирована люминесценция в диапазоне 980—1100 нм. На основании данных о строении электронных уровней в ионах Yb3+ сделан вывод о том, что возбуждение и излучение происходят непосредственно в ионах Yb3+ при пассивном участии решетки основания. В спектрах люминесценции имеется три максимума на длинах волн 993, 1025 и 1080 нм. Излучение в этих полосах обусловлено оптическими переходами электронов из возбужденного в основное состояние в ионах Yb3+. Изучена зависимость интенсивности люминесценции в полосе 993 нм от концентрации ионов активатора Yb3+. Установлено, что введение в состав люминофора ионов Na+ повышает интенсивность ИК-люминесценции. Предложен оптимальный состав люминофора (Ca1-x-yYbxNay)Ga2O4, при котором интенсивность люминесценции в полосе 993 нм максимальна