On the Problem of Wear Resistant Coatings Separation From Tools and Machine Elements

The article considers separation of wear resistant coatings of tool and engineering materials which arises both during coating fabrication and use of the product. The cause of this phenomenon is assumed to be related to thermal residual stresses generating on the coatingsubstrate border. These stresses have been analyzed and methods are provided to calculate it after produced composite material is cooled down from the temperature of coating synthesis to the ambient temperature. A no-fracture condition has been stated in relation to coatingsubstrate thicknesses, temperature differences and physical and mechanical properties of combined materials. The issue of intermediate layer incorporation with pre-set parameters has been discussed. A co-effect of thermal residual and functional stresses on the strength of the boundary layer has been considered when heating, tension and compression of a product with wear resistant coating. Conclusions have been made, as well as recommendations to improve fracture strength of products with thin wear resistant coatings

ANALIZA STANJA NAPREZANJA OBLOGE OKNA NA KONTAKTNOJ ZONI ANHIDRITA I KAMENE SOLI

The main question of this paper is the stress-strain state prediction of the vertical shaft’s combined lining located at the interface of two layers of dolomite and salt. The study predicts geomechanical processes at the contact of the dolomite layer and the salt layer in the vicinity of the vertical shaft’s expanded section, taking into account the operating life of a vertical shaft is equal to 50 years. The results combined lining’s stress-strain state, represented as a four – layer medium, where the external layer is concrete, and the three inner layers are used to account for the heterogeneity of cast-iron tubing and are compared with the results received when taking into account the pipe structure. The solution of the problem was carried out in a three-dimensional statement. The calculation of the tubing lining, considering its actual geometry, will increase the accuracy of the forecast of the stress state of the lining, which in turn will favourably affect the justification of its parameters.Glavna problematika ovoga rada očituje se u predviđanju stanja naprezanja – deformacije kombinirane obloge vertikalnoga okna smještene na kontaktu dvaju slojeva dolomita i soli. Studija predviđa geomehaničke procese na kontaktu dolomitnoga sloja i sloja soli u blizini proširenoga presjeka vertikalnoga okna, uzimajući u obzir radni vijek okna od 50 godina. Rezultati stanja naprezanja – deformacija kombinirane četveroslojne obloge, gdje je vanjski sloj beton, a tri unutarnja sloja od lijevanoga željeza, uzimajući u obzir heterogenost, uspoređeni su s rezultatima dobivenim kada je u obzir uzeta isključivo struktura cijevi. Rješenje problema provedeno je u trodimenzionalnome sustavu. Proračun obloge cijevi, uzimajući u obzir stvarnu geometriju, povećat će točnost predviđanja stanja naprezanja obloge, što upućuje na važnost parametara obloge

Detection of gene clusters for biodegradation of alkanes and aromatic compounds in the Rhodococcus qingshengii VKM Ac-2784D genome

Bacterial species of the genus Rhodococcus are known to be efficient degraders of hydrocarbons in contaminated soil. They are also employed for bioremediation of polluted environments. These bacteria are widely met in soil, water and living organisms. Previously, we have isolated the Rhodococcus qingshengii strain VKM Ac-2784D from the rhizosphere of couch grass growing on oil-contaminated soil. This strain can effectively degrade oil and some model compounds (naphthalene, anthracene and phenanthrene). The results of phylogenetic analysis show that this strain belongs to the species R. qingshengii. To understand the catabolic properties of this strain, we have studied its gene clusters possessing such properties. The alkane destruction genes are represented by two clusters and five separate alkB genes. The destruction of aromatic compounds involves two stages, namely central and peripheral. The R. qing­ shengii VKM Ac-2784D genome contains four out of eight known central metabolic pathways for the destruction of aromatic compounds. The structure of the gene clusters is similar to that of the known strains R. jostii RHA1 and R. ru­ ber Chol-4. The peripheral pathways include the genes encoding proteins for benzoic acid destruction. The presence of biphenyl 2,3-dioxygeneses as well as gene clusters of benzoate and 2-hydroxypentandienoate pathways suggests that R. qingshengii VKM Ac-2784D could degrade polychlorinated biphenyls. The biodegradation ability can be enhanced by biosurfactants, which are known to be synthesized by Rhodococcus. The R. qingshengii VKM Ac-2784D genome contains the otsA, otsB, treY, treZ genes. The bioinformatics data are supported by the previous biochemical experiments that allow a mixture of species with a wide variation of metabolic pathways to be obtained

The effect of cutting conditions on power inputs when machining

Any technological process involving modification of material properties or product form necessitates consumption of a certain power amount. When developing new technologies one should take into account the benefits of their implementation vs. arising power inputs. It is revealed that procedures of edge cutting machining are the most energy-efficient amongst the present day forming procedures such as physical and technical methods including electrochemical, electroerosion, ultrasound, and laser processing, rapid prototyping technologies etc, such as physical and technical methods including electrochemical, electroerosion, ultrasound, and laser processing, rapid prototyping technologies etc. An expanded formula for calculation of power inputs is deduced, which takes into consideration the mode of cutting together with the tip radius, the form of the replaceable multifaceted insert and its wear. Having taken as an example cutting of graphite iron by the assembled cutting tools with replaceable multifaceted inserts the authors point at better power efficiency of high feeding cutting in comparison with high-speed cutting

Автоматизация управления электроприводом обитаемого подводного аппарата

Currently, there is an intensive development of manned and unmanned submersibles due to development of offshore oil and gas fields, development of underwater archaeology and exploration activities in transit zones regarding seabed mineral extraction. The depth of immersion and the nature of the underwater technical works performed determine not only the design of the underwater vehicle, its power-to-weight ratio and technical equipment, but also impose high requirements on reliability, survivability, and habitability, if the underwater vehicle implies that the operator is on board inside a pressure hull. The main objectives of the study carried out by the authors were to achieve high reliability and survivability of the main elements of the propulsion-steering complex, which ensure movement of a human-occupied vehicle in the water column, its positioning and retention at a given point in the water area.For this purpose, it was proceeded to development of an automated control system for the electric drive of the propulsive device of manned immersible. The proposed developments include a flowchart of the movement control system, circuitry engineering solutions using power semiconductor devices to maintain operability of the electric drive in extreme and emergency operating conditions, and movement control algorithms. Electromagnetic calculations of the active part of the electric machine were performed by the finite element method, considering the geometric features of the dental zone of the rotor and stator. The proposed mathematical apparatus served to calculate optimal control actions of the electric drive and to quantitatively assess the reduction in electrical losses once optimal control was applied. The calculation of the optimal control parameters was carried out using the maximum principle. The initial conditions for auxiliary functions are determined by the Newton‒ Raphson method. A comparison of various modes of operation of the electric drive was made regarding their influence on duration of the campaign, and other parameters.The calculations did not consider the parameters and geometry of the propulsive device (the propeller) since the developers of electric propulsion systems for manned and unmanned underwater vehicles of various classes often deliberately reduce the efficiency of the propeller to increase speed of the electric motor shaft, resulting in a decrease in the dimensions and weight of the latter.В настоящее время происходит интенсивное развитие обитаемых и необитаемых подводных аппаратов благодаря освоению шельфовых нефтегазовых месторождений, развитию подводной археологии и геологоразведочной деятельности в транзитных зонах относительно добычи полезных ископаемых с морского дна. Глубина погружения и характер выполняемых подводно-технических работ определяют не только конструктивное исполнение подводного аппарата, его энерговооруженность и техническую оснащенность, но и предъявляют высокие требования по надёжности, живучести и обитаемости в случае, если подводный аппарат подразумевает нахождение оператора на борту внутри прочного корпуса. Основные цели проведённого авторами исследования – это достижение высоких показателей надёжности и живучести основных элементов движительно-рулевого комплекса, обеспечивающих движение обитаемого подводного аппарата в толще воды, его позиционирование и удержание в заданной точке акватории.Для этого была проведена разработка автоматизированной системы управления электроприводом движителей обитаемого подводного аппарата. Предложена блок-схема системы управления движением, разработаны схемотехнические решения с использованием силовых полупроводниковых приборов для поддержания работоспособности электропривода в экстремальных и аварийных условиях эксплуатации, разработаны алгоритмы управления движением. Электромагнитные расчёты активной части электрической машины выполнены методом конечных элементов с учётом геометрических особенностей зубцовой зоны ротора и статора. На основе предложенного математического аппарата рассчитаны оптимальные управляющие воздействия электроприводом и дана количественная оценка по снижению электрических потерь при оптимальном управлении. Расчёт оптимальных параметров управления осуществлялся с помощью принципа максимума. Начальные условия для вспомогательных функций определены методом Ньютона–Рафсона. Проведено сравнение различных режимов работы электропривода с их влиянием на продолжительность кампании и другие показатели.В проведённых расчётах не учитывались параметры и геометрия движителя – гребного винта, потому как разработчики систем электродвижения обитаемых и необитаемых подводных аппаратов различного класса часто намеренно идут на снижение коэффициента полезного действия винта в угоду увеличению частоты вращения вала электродвигателя, следствием чего является снижение габаритов и массы последнего

Estimating the cutting force when skiving with a radius cutter

The paper considers the method of determining the components of the cutting force under cutting completed with a radius cutter. The authors provide the design of the experimental study. The authors provide the data on the cutting force change in the process of turning with a radius cutter according to the cutting edge inclination, cutting depth and supply obtained experimentally and calculated analytically. The paper also provides the results of experimental work approximation and theoretical error checking related to experimental data

A facility to Search for Hidden Particles (SHiP) at the CERN SPS

A new general purpose fixed target facility is proposed at the CERN SPS accelerator which is aimed at exploring the domain of hidden particles and make measurements with tau neutrinos. Hidden particles are predicted by a large number of models beyond the Standard Model. The high intensity of the SPS 400~GeV beam allows probing a wide variety of models containing light long-lived exotic particles with masses below ${\cal O}$(10)~GeV/c$^2$, including very weakly interacting low-energy SUSY states. The experimental programme of the proposed facility is capable of being extended in the future, e.g. to include direct searches for Dark Matter and Lepton Flavour Violation.Comment: Technical Proposa

A facility to Search for Hidden Particles (SHiP) at the CERN SPS

A new general purpose fixed target facility is proposed at the CERN SPS accelerator which is aimed at exploring the domain of hidden particles and make measurements with tau neutrinos. Hidden particles are predicted by a large number of models beyond the Standard Model. The high intensity of the SPS 400~GeV beam allows probing a wide variety of models containing light long-lived exotic particles with masses below ${\cal O}$(10)~GeV/c$^2$, including very weakly interacting low-energy SUSY states. The experimental programme of the proposed facility is capable of being extended in the future, e.g. to include direct searches for Dark Matter and Lepton Flavour Violation

On-Line Student Modeling for Coached Problem Solving Using Bayesian Networks

This paper describes the student modeling component of ANDES, an Intelligent Tutoring System for Newtonian physics. ANDES' student model uses a Bayesian network to do long-term knowledge assessment, plan recognition and prediction of students' actions during problem solving. The network is updated in real time, using an approximate anytime algorithm based on stochastic sampling, as a student solves problems with ANDES.The information in the student model is used by ANDES' Help system to tailor its support when the student reaches impasses in the problem solving process. In this paper, we describe the knowledge structures represented in the student model and discuss the implementation of the Bayesian network assessor. We also present a preliminary evaluation of the time performance of stochastic sampling algorithms to update the network