The purpose of this article is to study and analyze the security threats in cloud environment and the applicability of cryptographic systems to protect the access to information resources. The threats to information security and the corresponding means for protection in cloud environment are discussed. Based on research and analysis of asymmetric and symmetric encryption are proposed flowcharts for secure communication over the Internet when using cloud services. The speed of different encryption and decryption of algorithms in cloud environment is measured, and are given recommendations for improving security.
Machines. Technologies. Materials.
Vol. 10 (2016), Issue 3
Table of Contents
Characteristics of operational reliability of agricultural plows, operating in mountainous conditions were determined on the basis of theoretical and experimental studies. It is shown that these conditions adversely affect their workability, cause intense wear of working parts of plows, and lead to failures. For this purpose, special coefficient was introduced which takes into account the impact of mountainous conditions on reliability.
A structural-logical scheme for reliability calculations was determined, and at the level of invention, a fundamentally new plow with variable widths was developed, allowing a better use of its operation in the mountainous conditions.
In this paper an experimental study of exhaust gas parameters of a modern diesel engine is presented. The engine under study is developed for passenger car. It was used a flexible engine management system based on National Instruments real-time controller and LabVIEW code. However, basic settings of the engine calibration values were used over the test. The engine was tested at seventeen operating points which correspond to real operating mode in NEDC of the vehicle. In order to define the engine speed and load a vehicle driving model was used. Finally, exhaust mass flow and temperature were studied as well as exhaust enthalpy was estimated. The results revealed that waste heat recovery system can be applied in order to reduce fuel consumption in NEDC.
COMPARATIVE ANALYSIS OF RANKINE CYCLE AND ORGANIC RANKINE CYCLE FOR WASTE HEAT RECOVERY IN INTERNAL COMBUSTION ENGINEpg(s) 14-17
This paper presents numerical analysis of waste heat recovery from engine exhaust gases by means of Rankine cycle and Organic Rankine cycle. Both technologies are widely studied in combustion engines but there are still not solid statements which should be chosen.
The heat source in this study is the exhaust system of a modern diesel engine, developed for passenger car. Firstly, the engine was experimentally studied at stationary operating mode. Thus, exhaust gas parameters such as: mass flow rate, temperature and enthalpy were obtained at seventeen operating points which correspond to real operating mode of vehicle in NEDC. A simulation model of waste heat recovery system was developed. Based on that model, a numerical code was created in Python as CoolProp open-source platform was used to determine working fluid parameters. Lastly, Rankine cycle and Organic Rankine Cycle output power and efficiency were studied. The results revealed that Organic Rankine cycle using R245fa as working fluid provides better efficiency than steam Rankine cycle. Maximum recovered power was estimated to be 1.69kW while for the steam Rankine cycle it was 1.43kW.
There are a number of hazards for people working in automobile repair shops related to the nature of the conducted operations, work in an environment of high temperature, chemicals, dust, gases, radiation, work with inflammable liquids, etc. By means of right zoning of the areas and appropriate choice of technological equipment it is possible to avoid hazards in the work zones of automobile repair shops.
Ground level ozone is one major secondary pollutant which is formed in the atmosphere by a variety of photochemical reactions involving volatile organic compounds and oxides of nitrogen in the presence of sunlight. Due to their reactivity, the exhaust emissions from heavy duty diesel engines are of particular concern and it is desirable to reduce the ozone forming potential of the exhaust emissions by reducing the mass of exhaust emissions. This study investigates the effect of retrofitted after-treatment devices and ultra-low sulfur diesel fuels on the ozone forming potential of exhaust emissions from heavy-duty off-road diesel engines. Specifically, the objective was to determine the effect of two diesel particulate filters and two ultra-low sulfur diesel fuels on the ozone forming potential from the 3 test diesel engines retrofitted with and without passive diesel particulate filters.
A GENERALIZED MATHEMATICAL MODEL OF OPTIMIZING INTERMODAL SUPPLY SYSTEM OF EXPORT CITRUS FRUITS TO INTERNATIONAL MARKETSpg(s) 24-25
The citrus fruits export supply system is a complex micro-logistics international transport logistical system. It pertains to intermodal transport supply chain of exported products. The central link in the chain is a regional agricultural logistic center, where the products are processing and preparing for shipping. The agricultural center is distinguished by a multitude of possible ties with suppliers and buyers, and as far as possible it is located in their geographic center.
The goal of the logistic system as a complex structure, is to create an optimally functioning logistic system and develop a scientific- technical methodology of development on the basis of principles of intermodality, international marketing and supply chain management in the conditions of an indeterminate impact of external factors.. In accordance with the developed optimization procedures, there have been optimized the parameters and and selected the values of studying parameters at a level of probability belief.
In regional market of tourist transport services, it is necessary to find new forms of relationships between the market entities, since the currently existing forms are characterized by many negative aspects, and in modern economic conditions they are inadequately effective. As a result of analyzing and carrying out research works on organizational models currently existing in the market of tourist transport services, it has been established that at a regional level that it is expedient to find such a form of relationships between the market entities as consolidation of travel companies and transporters (having specialist vehicles). Such form of consolidation allows for resolving numerous problems arising during the travel catering process, as well as enables travel companies to be more efficient, reduce the number of intermediaries between the market entities, minimize costs and improve the quality of transport services.
Energy efficient improvement and bringing to conformity with long-term environmental safety requirements are considered as an important stage to improve ship engines. The values of the mentioned characteristics are mostly determined by the type of consumed fuel and organization of operational process that in turn conditions the intensity of the process of combustion and heat release in the cylinder. And these parameters are the determined factors in the view of improving the technical and economic performance of diesel engines. From this point of view, at this stage conversion some types from the ship diesel engine cycle into the gas diesel engine cycle.
The paper aims to determine the heat release characteristics on the basis of theoretical and experimental analysis of ship engine performance when implementing the operational process of both diesel engine and gas diesel engine cycles. The given paper dwells on comparative characteristic and efficiency analysis of diesel engine and gas diesel engine cycles, on the basis of experimental modeling.
This article reviews the question related to the determination of a carriage duty in the multimodal transportation system. In the following calculations there was given the comparison between the methodic of Rail – Tariff and United Transit Tariff (UTT). In terms of the research, through shoulder scheme of carriage duty based on the supranational currency EuroNur protected by certificate of the authorship is proposed.
MIXED TRAFFIC WITH DIFFERENT PERCENTAGE RATES OF ELECTRIC VEHICLES AND ITS ENVIRONMENTAL INFLUENCE IN URBAN AREASpg(s) 38-41
The development of high power electronics, improvement of existing and emerging of new battery technologies and optimization of electric motors over the last decade are some of the issues that have raised the interest in electric vehicles. Based solely on tank to wheel analyses, electric vehicles are regarded as zero emission vehicles. Regarding these facts, the research presented in this paper is focused on mixed traffic with different percentage rates of electric vehicles and its environmental influence in urban areas. A model of a mixed traffic stream comprised of conventional and electric vehicles was built upon a microscopic single lane urban traffic simulator.
Through number of parallel simulations of solely conventional and mixed traffic stream and analysis of the results, we have evaluated the influence that certain presence rates of electric vehicles in the mixed traffic stream have on the exhaust emission. The results that we have obtained are constrained by the assumption that the electric energy used by the electric vehicles originates from renewable energy sources.
A RESEARCH ABOUT INFLUENCE OF WIRE ELECTRODE VIBRATION’S AMPLITUDE UPON TECHNOLOGICAL PARAMETERS OF VIBRATING GAS METAL ARC OVERLAYING PROCESS IN A SHIELD OF ARGONpg(s) 42-43
A research about influence of wire electrode vibration’s amplitude upon process of arc-cycle conduction and forming of over- laid coating is done in a shield of argon. Duty cycle frequency, times of short circuit and arc burning as well as roughness of the coating are used as quality criteria. It is established that wire electrode vibration’s amplitude cause a significant influence as maximal value of arc cycles and lowest roughness of the coating are obtained at rate of 2 mm.
The aim of this work is numerical modeling of the hydrodynamics and heat transfer of a shell-and-tube heat exchanger. For the purpose of the study a 3D model with geometric dimensions corresponding to real was created. The simulations under the same boundary conditions as experiment were carried out. The independence of solution by the density and the shape of the mesh were investigated. For verification the experimental values for fluid temperatures at the outlets from the apparatus were used. The simulations of different operation modes in the apparatus were carried out. A modification in the geometry with the aim of raising the temperature on the cold fluid at the outlet was made. Results on vectors, velocity and temperature distribution in the apparatus were obtained. On the basis of the obtained results some design changes of the apparatus in order to improve the hydrodynamics have been proposed. The obtained results can be successfully used in the design, optimization and constructing of this type apparatus, as well as in the educational process.
DETERMINATION OF THE THERMODYNAMIC FUNCTIONS OF HEAVY HYDROCARBON CRUDE (COAL TAR) AND HYDROGENATION PRODUCT BY ADDITIVE PROCESSpg(s) 48-51
The purpose of the work is to determine the thermodynamic functions of: heat capacity (ΔСр), enthalpy (ΔН), entropy (ΔS), Gibbs free energy (ΔG) and the specified thermodynamic potentials (ΔФ **)of the organic mass of coal (OMC) and the organic mass of the primary coal tar (PCT) obtained in the process of hydrogenation.
Experimental investigation of the modification of starch by grafting acrylamide using electron beam irradiation in order to synthesize water-soluble copolymers having flocculation abilities is performed. The influence of the variation of the parameters acrylamide/starch (AMD/St) weight ratio, electron beam irradiation dose and dose rate, as well as the presence or absence of metallic silver nanoparticles is investigated. The characterization of graft copolymers was carried out by monomer conversion coefficient, residual monomer concentration, intrinsic viscosity and Huggins’ constant. Models, describing the dependencies of the quality characteristics (their means and variances) from the process parameters, are estimated by implementation of the robust engineering approach in the case of qualitative and quantitative factors. Multi-criteria optimization involving requirements for economic efficiency, assurance of low toxicity, high copolymer efficiency in flocculation process and good solubility in water is also presented.
FEATURES FORMATION OF THE BORIDES TRANSITION METALS LAYERS BY AN ELECTRON-BEAM SURFACING OF SHS PRODUCTS IN VACUUMpg(s) 56-58
The formation features of transition metals borides at high temperatures and low pressures were investigated and discussed the conditions of formation, structure and wear properties of boride layers on the surface, formed in electron beam processing in a vacuum.