Обоснование параметров канатных анкеров для крепления выработок в условиях слоистых пород

Purpose. The development of approaches to the substantiation of the cable bolts installation parameters for the mine workings supporting in conditions of laminated rocks, taking into account the geometric parameters of the rocks disintegration zone. Methods. The parameters of the rocks disintegration zone in the roof of a single mine working and a mine working in the area of a longwall influence are determined by the in-situ investigations. Findings. The existing approaches to the cable bolt installation parameters are considered. The rock deformation mechanism around a single mine working is introduced. The results of the experimental supporting of mine working with roof bolts in conditions of Western Donbass are analyzed. The results of studying of rock mass deformation in the roof of the gateroad in the area of longwall influence are presented. Originality. The deformation of the rock mass around a single mine working occurs in the form of extrusion wedges of laminated rocks in the roof and floor. Behind longwall face the zone of rocks disintegration formed at a height of 6 m in the roof and the overlying strata sagged by up to 0.2 m without delaminating. Practical implications. Taking into account the geometric parameters of the rocks disintegration zones the installation parameter of cable bolts for the mine working roof supporting are substantiated. Experiments proved that the increasing of the cable bolt installation density reduces the intensity of the gateroad roof rock deformation at the face – end.Цель. Разработка подходов к обоснованию параметров установки канатных анкеров с учетом геометрических параметров зоны дезинтеграции пород для крепления выработок в условиях слоистых пород. Методика. Натурными исследованиями установлены параметры зон дезинтеграции пород кровли одиночной выработки и выработки в зоне влияния очистных работ. Результаты. Рассмотрены существующие способы обоснования параметров установки канатных анкеров. Приведен механизм деформирования пород вокруг одиночной выработки. Проанализированы результаты эксперимента по креплению выработки анкерной крепью в условиях Западного Донбасса. Приведены результаты исследований закономерностей деформирования пород кровли подготовительной выработки в зоне влияния очистных работ. Научная новизна. Деформирование массива пород вокруг одиночной выработки происходит в виде формирования клиньев выдавливания слоистых пород почвы и кровли. За очистным забоем зона дезинтеграции пород формируется на высоту 6 м в кровлю выработки, а вышележащий массив опускается на величину до 0.2 м без расслоений. Практическая значимость. С учетом геометрических параметров зон дезинтеграции обоснованы параметры установки канатных анкеров для крепления кровли выработок в условиях слоистых пород. Экспериментально установлено, что увеличение плотности установки канатных анкеров приводит к уменьшению интенсивности деформирования пород кровли выработки на сопряжении “лава – штрек”.Мета. Розробка підходів до обґрунтування параметрів установки канатних анкерів з урахуванням геометри- чних параметрів зони дезінтеграції порід для кріплення виробок в умовах шаруватих порід. Методика. Натурними дослідженнями встановлено параметри зон дезінтеграції порід покрівлі одиночної виробки та виробки у зоні впливу очисних робіт. Результати. Розглянуто існуючі способи обґрунтування параметрів установки канатних анкерів. Наведено механізм деформування порід навколо одиночної виробки. Проаналізовано результати експерименту з кріплення виробки анкерним кріпленням в умовах Західного Донбасу. Наведено результати досліджень закономірностей деформування порід покрівлі підготовчої виробки у зоні впливу очисних робіт. Наукова новизна. Деформування масиву порід навколо одиночної виробки відбувається у вигляді формування клинів видавлювання шаруватих порід підошви та покрівлі. За очисним забоєм зона дезінтеграції порід формується на висоту 6 м у покрівлю виробки, а вищезалягаючий масив опускається на величину до 0.2 м без розшарувань. Практична значимість. З урахуванням геометричних параметрів зон дезінтеграції обґрунтовані параметри установки канатних анкерів для кріплення покрівлі виробок в умовах шаруватих порід. Експериментально встановлено, що збільшення щільності установки канатних анкерів призводить до зменшення інтенсивності деформування порід покрівлі виробки на сполученні “лава – штрек”.Авторы выражают свою искреннюю благодарность коллективу инженерно-технических работников ш. “Самарская” и ш. “Степная” за помощь в организации и проведении натурных наблюдений в горных выработках

Three Problems of the Theory of Choice on Random Sets

This paper discusses three problems which are united not only by the common topic of research stated in the title, but also by a somewhat surprising interlacing of the methods and techniques used. In the first problem, an attempt is made to resolve a very unpleasant metaproblem arising in general choice theory: why the conditions of rationality are not really necessary or, in other words, why in every-day life we are quite satisfied with choice methods which are far from being ideal. The answer, substantiated by a number of results, is as follows: situations in which the choice function "misbehaves" are very seldom met in large presentations. In the second problem, an overview of our studies is given on the problem of statistical properties of choice. One of the most astonishing phenomenon found when we deviate from scalar-extremal choice functions is in stable multiplicity of choice. If our presentation is random, then a random number of alternatives is chosen in it. But how many? The answer isn't trivial, and may be sought in many different directions. As we shall see below, usually a bottleneck case was considered in seeking the answer. It is interesting to note that statistical information effects the properties of the problem very much. The third problem is devoted to a model of a real life choice process. This process is typically spread in time, and we gradually (up to the time of making a final decision) accumulate experience, but once a decision is made we are not free to reject it. In the classical statement (i.e. when "optimality" is measured by some number) this model is referred to as a "secretary problem", and a great deal of literature is devoted to its study. We consider the case when the notions of optimality are most general. As will be seen below, the best strategy is practically determined by only the statistical properties of the corresponding choice function rather than its specific form

The effect of a heteroatom on the structure and vibrational spectra of Heteroannulated tetraphenylenes

Based on calculations by the DFT method, we have theoretically compared IR absorption and Raman spectra of tetraoxa[8]circulene (4O) and its analogs that contain sulfur (4S) and selenium (4Se) atoms. Calculations have shown that the structure of investigated molecules and observed shifts of similar vibrations in their IR and Raman spectra are interrelated. We have constructed correlation schemes of frequency shifts of normal vibrations upon passage from planar 4O circulene to its 4S and 4Se nonplanar analogs. The obtained data are of fundamental interest both from the point of view of specific selection rules and in the context of the novelty of the force field, where the conjugation of the internal and external macrocycles with heteroatoms manifests itself

Vicious Walkers and Hook Young Tableaux

We consider a generalization of the vicious walker model. Using a bijection map between the path configuration of the non-intersecting random walkers and the hook Young diagram, we compute the probability concerning the number of walker's movements. Applying the saddle point method, we reveal that the scaling limit gives the Tracy--Widom distribution, which is same with the limit distribution of the largest eigenvalues of the Gaussian unitary ensemble.Comment: 23 pages, 5 figure

Hyperbolicity Measures "Democracy" in Real-World Networks

We analyze the hyperbolicity of real-world networks, a geometric quantity that measures if a space is negatively curved. In our interpretation, a network with small hyperbolicity is "aristocratic", because it contains a small set of vertices involved in many shortest paths, so that few elements "connect" the systems, while a network with large hyperbolicity has a more "democratic" structure with a larger number of crucial elements. We prove mathematically the soundness of this interpretation, and we derive its consequences by analyzing a large dataset of real-world networks. We confirm and improve previous results on hyperbolicity, and we analyze them in the light of our interpretation. Moreover, we study (for the first time in our knowledge) the hyperbolicity of the neighborhood of a given vertex. This allows to define an "influence area" for the vertices in the graph. We show that the influence area of the highest degree vertex is small in what we define "local" networks, like most social or peer-to-peer networks. On the other hand, if the network is built in order to reach a "global" goal, as in metabolic networks or autonomous system networks, the influence area is much larger, and it can contain up to half the vertices in the graph. In conclusion, our newly introduced approach allows to distinguish the topology and the structure of various complex networks

Case report of sclerochoroidal calcification

Background. Sclerochoroidal calcification is an idiopathic rare benign lesion of the sclera or choroid characterized by histological deposition of calcium pyrophosphate. Taking into consideration its similar clinical manifestations with other diseases of the sclera, the most dangerous of which are malignant, timely verification of the diagnosis with the appointment of a further observation period is important.The aim. The description of a clinical case of sclerochoroidal calcification to improve the efficiency of disease detection through the use of multimodal diagnostics.Material and methods. A 62-year-old patient with complaints of “bright flashes” in her left eye for the past few months, who underwent a standard complex of ophthalmological examinations, supplemented according to indications by optical coherence tomography of peripapillary nerve fibers, macular zone, B-scan, Dopplerography in color Doppler mapping mode. Auxiliary diagnostic methods were magnetic resonance imaging of the orbits and extraocular muscles, computed tomography of the orbits and a biochemical blood test.Results. Considering the anamnesis, the absence of progression of complaints, the data of instrumental diagnostic methods, the absence of pathological blood flow in the area of both eyes formations, the correct diagnosis is most likely to be sclerochoroidal calcification of both eyes, despite the difficulties of the diagnostic process, which consisted in the absence of visualization of foci during ophthalmoscopy. Conclusion. Sclerochoroidal calcification is of interest to practicing ophthalmologists due to the difficulties of diagnostic search and differential diagnosis with malignant neoplasms. Modern medicine has a sufficient set of instrumental and laboratory research methods for making an accurate diagnosis

On the partial connection between random matrices and interacting particle systems

In the last decade there has been increasing interest in the fields of random matrices, interacting particle systems, stochastic growth models, and the connections between these areas. For instance, several objects appearing in the limit of large matrices arise also in the long time limit for interacting particles and growth models. Examples of these are the famous Tracy-Widom distribution functions and the Airy_2 process. The link is however sometimes fragile. For example, the connection between the eigenvalues in the Gaussian Orthogonal Ensembles (GOE) and growth on a flat substrate is restricted to one-point distribution, and the connection breaks down if we consider the joint distributions. In this paper we first discuss known relations between random matrices and the asymmetric exclusion process (and a 2+1 dimensional extension). Then, we show that the correlation functions of the eigenvalues of the matrix minors for beta=2 Dyson's Brownian motion have, when restricted to increasing times and decreasing matrix dimensions, the same correlation kernel as in the 2+1 dimensional interacting particle system under diffusion scaling limit. Finally, we analyze the analogous question for a diffusion on (complex) sample covariance matrices.Comment: 31 pages, LaTeX; Added a section concerning the Markov property on space-like path

In vitro culture with gemcitabine augments death receptor and NKG2D ligand expression on tumour cells

Much effort has been made to try to understand the relationship between chemotherapeutic treatment of cancer and the immune system. Whereas much of that focus has been on the direct effect of chemotherapy drugs on immune cells and the release of antigens and danger signals by malignant cells killed by chemotherapy, the effect of chemotherapy on cells surviving treatment has often been overlooked. In the present study, tumour cell lines: A549 (lung), HCT116 (colon) and MCF-7 (breast), were treated with various concentrations of the chemotherapeutic drugs cyclophosphamide, gemcitabine (GEM) and oxaliplatin (OXP) for 24 hours in vitro. In line with other reports, GEM and OXP upregulated expression of the death receptor CD95 (fas) on live cells even at sub-cytotoxic concentrations. Further investigation revealed that the increase in CD95 in response to GEM sensitised the cells to fas ligand treatment, was associated with increased phosphorylation of stress activated protein kinase/c-Jun N-terminal kinase and that other death receptors and activatory immune receptors were co-ordinately upregulated with CD95 in certain cell lines. The upregulation of death receptors and NKG2D ligands together on cells after chemotherapy suggest that although the cells have survived preliminary treatment with chemotherapy they may now be more susceptible to immune cell-mediated challenge. This re-enforces the idea that chemotherapy-immunotherapy combinations may be useful clinically and has implications for the make-up and scheduling of such treatments

MoS2@ZnO Nanoheterostructures Prepared by Electrospark Erosion for Photocatalytic Applications

MoS2@ZnO nanoheterostructures were synthesized by electrospark erosion of zinc granules in a hydrogen peroxide solution and simultaneous addition of MoS2 nanostructured powder into the reaction zone. The morphology, size of the crystallites, as well as elemental and phase composition of the prepared structures, were examined using transmission electron microscopy and X-ray diffraction analysis. It was found that the synthesized products represent heterostructures containing MoS2 nanoparticles formed on ZnO nanoparticles. Raman spectroscopy and photoluminescence analysis were also used for characterization of the prepared heterostructures. The obtained MoS2@ZnO nanostructures revealed an intense broad emission band ranging from 425 to 625 nm for samples with different fractions of MoS2. Photocatalytic measurements showed that the maximal hydrogen evolution rate of the prepared nanoheterostructures was about 906.6 μmol·g−1·h−1. The potential of their application in photocatalytic water splitting was also estimated