Machines. Technologies. Materials.
Vol. 10 (2016), Issue 2

Table of Contents

  • DENSITY FUNCTIONAL STUDY of LuSe and LuTe INTERMETLLIC COMPOUNDS

    pg(s) 3-4

    Calculations have been performed to study the structural, electronic, elastic, mechanical, thermodynamical and phonon properties of LuS and LuTe with the generalized gradient approximation for exchange and correlation. The calculated lattice constants, bulk modulus, its pressure derivative and elastic constants are calculated. The calculated values of lattice constant are in good agreement with the experimental and theoretical results. The elastic constants have been derived from the slopes of the acouistic branches in the phonon dispersion-curves. The electronic band structure and, total and partial density of states of these compounds have been computed and analysed. The phonon dispersions curves of LuSe and LuTe for B2 phase are computed using density functional perturbation theory (DFPT) with generalized gradient (GGA) approximations. We also used the quasiharmonic approximation to calculate some thermodynamic properties such as constant-volume specific heat capacity of the B2 phase of LuS and LuTe compounds.

  • SIMULTANEOUS THERMAL ANALYSIS ON PLASMA-AIDED CAPILLARY IMPREGNATION FOR EUROPEAN WHITE PINE FLAME RETARDATION IMPROVEMENT

    pg(s) 5-8

    Simultaneous Thermal Analysis (STA, TGA and DSC) unifies the simultaneous application of thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) to one and the same wood sample in a single instrument, under perfectly identical conditions – same atmosphere, gas flow rate, pressure, heating rate, thermal contact, etc. New thermal analysis approaches for integral distinguishing between the flaming and glowing combustion of wood were discussed. The results obtained by STA were used in a new way in order to reveal the influence of plasma-aided capillary impregnation on thermal decomposition and glowing of wood controlled by oxygen and nitrogen containing flame re- tardant. New integral criterion of thermal behavior and decomposition such as specific enthalpy change has been developed by investigating samples of European White Pine (Pinus Sylvestris, Bulgaria) wood. This study has been developed also as part of a large investigation on plas- ma-chemically activated (polarized, functionalized) wood surface and its capillary impregnation with nitrogen- and phosphor flame retardant containing water solution.

  • INVESTIGATION OF FAILURE OF FREIGHT TRUCKS SIDE FRAMES USING ACOUSTIC EMISSION

    pg(s) 9-10

    Analysis of material condition of side frames of freight trucks before and after thermal hardening was performed by combined analysis of Acoustic Emission (AE) and strain diagrams during tests of samples cut from the frames. The kinetic of damage accumulation during loading to failure in the material after normalizing or volume-surface hardening was analyzed. Changes in ductility and toughness resource of the metal was evaluated.

  • BASIC APPROACHES TO THE STUDY OF THE STRUCTURE AND PROPERTIES OF THIN OXIDE LAYERS ON THE EXAMPLE OF THE OXIDE FILMS OF ZIRCONIUM ALLOYS

    pg(s) 11-12

    The structure and mechanical properties of the oxide films formed on zirconium alloys Zr – 1% Nb, Zr – 2,5% Nb upon autoclave tests at a temperature of 360oC and pressure of 18,6 MPa for 600 days were studied. Basic methodological approaches to the study of the structure and properties of thin oxide films were shown. The 10-15 µm thick oxide films of different structural types were shown to be formed on the specimens: the structures with predominately elongated grains and the layered structures. The structure of the oxide films subjected to loading determines both the crack formation stress and the character of fracture.

  • INVESTIGATION OF HIGH-TEMPERATURE MULTI-LAYER MATERIAL BASED ON VANADIUM ALLOY AND STAINLESS STEEL

    pg(s) 13-14

    The investigation of the interface connection area of the three-layer tube "steel / vanadium alloy / steel" after different deformation-heat treatments was performed. Furthermore, a qualitative and quantitative analysis of the structure of the three-layer material were conducted, including analysis of the contact area of the steel and the vanadium alloy and the diffusion layer between them was obtained. The analysis of the microstructure and mechanical properties (microhardness, ultimate tensile strength, yield strength and elongation) of three-layered material has been carried out.

  • THE EFFECT OF CHEMICAL COMPOSITION ON PROPERTIES OF ROCK MELTS

    pg(s) 15-18

    The results of investigations of basic physical and chemical properties for aluminosilicate melts of different compositionsis presented. It is shown that the highest values of surface tension and adhesion was observed for the basalt melts, whereas neutral aluminosilicate glass melts without iron oxides in their composition are characterized by a high value of contact angle and the lowest values of surface forces. The insertion in the melt of ZrO2 increases significantly wetting angles, surface tension and adhesion throughout the temperature range as compared with the same melts without zirconia. Basalt melts differ by lower viscosities and significantly less sensitivity to the effects of additives on viscosity of zirconium oxide as compared to the andesite-basalt melts.

  • INVESTIGATION OF PROPERTY OF POLYCRYSTALLINE DIAMOND PURIFIED BY TECHNOLOGY OXIDATIVE ALKALINE MELTS

    pg(s) 19-203

    Properties of polycrystalline nanodiamond powder after treatment under oxidizing alkali melts of sodium nitrate and sodium hydroxide were investigated. It is established that the dried initial product contains the particles with size up to 100 microns, which are easily broken by ultrasonic treatment to size about 15 micron. A comparative grain-size analysis of samples before and after treatment of oxidative alkaline melts showed that the average grain size is reduced to 6 microns and the particles of less than 1 micron are formed. It is shown that after treatment in the oxidative alkaline melt final material does not contain non-diamond carbon and the dried powder of polycrystalline diamond practically does not aggregate.

  • AN EXPERIMENTAL INVESTIGATION OF LIME BASED PLASTERS MOISTURE AND TEMPERATURE INDUCED DEFORMATION.

    pg(s) 21-23

    The problem of the reconstruction of the historical building coat is in material comparability. The basic of the convenient material choice for reconstructions is to recognize some physical properties of used materials. The crucial properties are moisture and temperature induced expansion. The objective of this paper is to experimentally determine moisture and temperature induced deformations of two lime based plasters. The measurements are performed for moisture content from the dry state to the saturation water content and temperature range of 5 – 60°C. Temperature and moisture induced length differences were measured using LVDT MACRO SENSOR SBP 375040.

  • ANALYSIS OF PARALLEL RESONAT CONVERTERS WITH COMPUTER SIMULATIONS

    pg(s) 24-27

    In this paper analysis of power converters with parallel resonant circuit by using of computer simulations is made. The full bridge IGBT power converter is analyzing. The simulations are made in PowerSim simulation program. Calculation is the efficiency of the converter and is made harmonic analysis of the output voltage and current. Also, is made and compare on the obtained results of the parallel resonant converter with the results of the serial resonant converter in applications with variable RL-load.

  • STUDY OF THE CAPACITY OF A FANUC M430i-A/4FH ROBOT TO PERFORM TECHNOLOGICAL OPERATIONS

    pg(s) 28-30

    A work environment for modelling, simulating and performing various technological operations (milling, drilling, etc.) has been created using hardware developed to include a Fanuc M430i-A/4FH robot and specialised software Roboguide. As a result of the study, guidelines have been developed for the software and hardware improvement of the system in order to enhance its use both for the purposes of training and research.

  • COMPARATIVE ANALYSIS OF CONTEMPORARY CASE BASED REASONING SOFTWARE FRAMEWORKS

    pg(s) 31-34

    The paper presents the comparison of two Case-Based Reasoning (CBR) oriented software frameworks myCBR3 Workbench and CBR-Works ver. 4.3.0 for the development of predictive diagnosis and maintenance systems. Those frameworks were selected after detailed preliminary comparisons of previous versions of myCBR presented in, as well of the investigations of the capabilities of other 4 popular CBR software systems. The evaluation of myCBR and CBR-Works includes the capacity to support the: R CBR circle; clusterization of cases, variety of used similarity functions, etc. Specific abilities to provide GUI, database support, required knowledge to work with the systems were also considered.

  • ONTOLOGY BASED DATA AND INFORMATION INTEGRATION IN BIOMEDICAL DOMAIN

    pg(s) 35-38

    One of the main problems of biomedical informatics in the effort to increase its contribution in knowledge retrieval and decision making is the integration of ever-increasing amounts of information and data from multiple heterogeneous sources and domains – clinical, medical, biological etc. The paper proposes an ontology based approach for integration of biomedical data and information using the Linked Open Data vocabularies and a D2RQ-mapped database. A simple example of semantic integration of heterogeneous biomedical and health data sources is given.

  • METAMODELS BASED ONTOLOGY DEVELOPMENT TO ACHIEVE STANDARD-COMPLIANT PROJECT MANAGEMENT

    pg(s) 39-42

    The present paper illustrates the current state of affairs for most organizations involved in the sphere of Information technologies that run or strive to run projects in accordance with applicable ISO standards and CMMI. This paper presents the target state of affairs and its design with used technologies. Reaching the goal state is summarized by serialization of metamodels in XML, mapping/parsing of metamodels (in XML) to OWL2 DL (RL profile) ontologies (written/exchangeable in RDF/XML), storages of these semantic metamodels and models (ontologies/semantic data) in advanced RDBMSs with support of ontologies, R2RML mapping of existing project-related relational data to semantic data and storage of semantic data in semantic stores hosted in existing RDBMSs or migration to such ones, extraction of non-relational project-related data and mapping of these logical models to a physical (relational) model and integration in RDBMSs to centralize all project-related data all governed by the defined vocabularies (ontologies of CMMI for Development and ISO 15504/ 12207). Achieving the goal state enables stakeholders to query and infer from project-related semantic data to manage, analyze and assess projects against underlaying standards. Through commonly-accepted adapters, semantic data, metamodels and models are exposed to external applications.

  • DETERMINATION OF THE OPTICAL PROPERTIES OF BULGARIAN HONEY AND THEIR APPLICATION TO HONEY DISCRIMINATION

    pg(s) 43-46

    The aim of the article is to investigate the optical properties of Bulgarian honey in regard to the potential of honey discrimination on the base of its botanical origin. Samples from three types of honey (acacia, linden, and honeydew) are measured by a fluorescence spectrometer recording emission from 350 to 800 nm with excitation at 370, 395 and 405 nm. A combination of fluorescence emission spectra with some colorimetric parameters (CIELab) is used as input data of three types of honey classifiers: the first two are based on linear and quadratic discriminant analysis, and the third one uses an artificial neural network. The neural classifier is realized as a multilayered perceptron with backpropagation learning algorithm. Principal components analysis (PCA) is used for reducing the number of inputs and for a proper visualization of the experimental results. The comparative analysis of the three classifiers is based on leave-one-out-cross validation test carried out in MATLAB environment.

  • MODEL DRIVEN DEVELOPMENT OF AGENT BASED AMBIENT INTELLIGENCE PLACES WITH SERVICE ORIENTED ARCHITECTURE

    pg(s) 47-50

    In recent years the use of computer technique and information technology in the domain of Ambient Intelligence (AmI) has been increasing significantly. For successful and efficient development of ambient intelligence systems and their components a new approach is needed. The Model Driven Development (MDD) is an innovative approach for development of different software applications using models at different levels of abstraction and applying model transformation to code generation. In order to satisfy the basic requirements to the developed AmI, in the proposed approach, the MDD, based on Model Driven Architecture (MDA), is directed to combine the use of agents as basic elements of the system and to model the internal and external communications in the system, based on the concept of Service Oriented Architecture (SOA). Such a way, the paper proposes a layered modeling framework for model driven development of agent based AmI systems with service oriented architecture. The deployment of the software on hardware resources is also part of the software process model. Finally some conclusions are made.

  • AN APPROACH FOR COMBINING THE CAPABILITIES OF IMMERSIVE VIRTUAL REALITY AND MODERN CAD-CAM SOFTWARE SYSTEMS TO CREATE VIRTUAL MODELS OF WORKSHOPS FOR MECHANICAL PROCESSING

    pg(s) 51-54

    The article describes an approach for creation virtual reality scenes of workshops for mechanical processing, using three- dimensional models from CAD/CAM and on the basis of "immersion" of the designer in a virtual environment. Applications software and hardware resources used to achieve the interaction between CAD/CAM models of the machine tools, equipment and human avatars and virtual reality environment are described. Conclusions for the advantages and problems of the proposed approach and guidelines for future work also are given.

  • SOME PROJECT MANAGEMENT TECHNIQUES

    pg(s) 55-58

    There are many specific techniques involved in each of the four major sets of activities called POMA (Planning, Organizing, Monitoring, and Adjusting) phases. Some require extremely deep technical knowledge and others demand great social skills, in this section, we will focus on four commonly needed project management skills: project effort estimation, work breakdown structure, project status tracking with earned value and development measuring & metrics The first two of them are techniques needed in the planning and organizing phases, and the third is needed in the monitoring phase. The fourth is needed for part of planning and for monitoring.

    In the report they have explained some techniques for estimating software project management