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Recent 21

Vol. 8 (2007), No. 3 (21 a, b), November 2007

The 21st issue of RECENT journal was edited and multiplied with support of:

  • Romanian Association of Unconventional Technologies,

  • Transilvania University of Brasov,

  • Brasov County Council (by Scientific Activities, Education, Culture, Cults Committee)


CONTENTS


No. 3 (21 a)


  • Carmen Gabriela BĂCILĂ, Zoltan-Gabor BAKI-HARI

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The Main Applications of Rapid Tooling

» Abstract. Because of the technical and scientific discoveries, nowadays the different processes and technologies are continuously developed and improved. Consequently, their application potential is widening, arriving even to some strange applications. That can be told also about the Rapid Tooling (RT) which can be considered as a special, larger application of the Rapid Prototyping (RP), because it is based on the RP models. The main applications of Rapid Tooling are those intended to obtain flexible tools. Through such methods, the active parts of different dies for plastics forming or entire silicon rubber dies, used for the fabrication of small series products, can be manufactured. Through Rapid Tooling also massive electrodes for Electro Discharge Machining (EDM), or monobloc or hybrid patterns for casting can be manufactured.

» Keywords: rapid tooling, rapid prototyping, rapid manufacturing, rapid moulding, product development, CAD-CAM


  • Nicolae BOIAN

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DIAGNOSTIC OF COMPETITIVE POSITION AT SMALL AND MIDDLE SIZE COMPANIES

» Abstract. The paper presents a model of competitive position analyze at small and middle size companies, based on open system theory according which, company’s activity is potently influenced by environmental forces of competition. The proposed model is a Michael Porter representation of environmental competition which takes account of specificity of small and middle size company’s activity. The model brings in front a new system of competition forces and especially a new ratio of different kind of pressure points. Diagnose is focused to main factors of each kind of pressure forces which are simultaneously evaluated as sense and intensity. Model proposes a general plan of analyses, developed on stages, which allow making evident the main elements that do not miss into analyze. Finally paper present an example of evaluation of competition position of a small package factory. Conclusions refer to implication of analyze results on company’s management strategy.

» Keywords: competition, competitive forces, evaluation, determinant factors, process, pressure forces


  • Gheorghe BONCOI, Magdalena BARBU, Ionel NOVAC

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Forward-Looking Mathematical Model Developed to Forecast the Technical-Economic Environment in Manufacturing Heat-Insulation Carpentry. Application Conditions

» Abstract. The paper presents the application conditions of a model developed to forecast the technical-economic environment in manufacturing heat-insulation carpentry; the model consists of product definition, initial data and previously calculated values. The following are defined: products, production volumes, related probabilities, production percentage, forecast probability, assumed risk, uncertain environment, decision under uncertainty conditions, decision robustness; a calculation procedure of forecast probabilities is also forwarded. The paper approaches the application conditions of the model under conditions of flexible manufacturing of heat-insulation materials on sets of products. The model is probalistic or uncertain, by taking into account the assumed risk.

» Keywords: mathematical model, technical-economic environment


  • Gheorghe BRĂTUCU, Melania SUCIU

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Appearances Concerning the Predictable Reliability of the Automation System on the Advances Mechanism from the Lathes with Digital Commanding

» Abstract. In the work it’s studied the predictable reliability of the automation system from the lathes with digital commanding SPT 32, which is compared with they operational reliability. There are tested two lots of 12 lathes, whereat the automation mechanisms had in structure mechanic and hydraulic elements (the lot 1), respectively mechanics and electric-electronic elements (the lot 2). The observation period was of the precinct 20000 hours, respectively 5 years of work. The mechanic components had the same behavior both constructive variants, conversely the hydraulic components presented much more broke downs comparative with the electric-electronic components. For both variants is calculated firstly the predictable reliability, through the utilization of constant intensity of the breakdowns λ, recommended from the specialty literature. Abaft effectuation of the operational reliability studies they consisted in sensitive differences between the breakdown intensities between of the two automation systems variants, but also comparative with calculating values to the predictable reliability.

» Keywords: lathes with digital commanding, automation mechanisms, predictable reliability


  • Milan BROˇEK, Rostislav CHOTĚBORSKŻ, Miroslav MÜLLER, Petr HRABĚ

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OPTIMIZATION OF CUTTING CONDITIONS AT DRILLING

» Abstract. In the paper the long term tests results of twist drill cutting life are summed up. The were tested drills were made from improved high speed steel in two versions – HSS uncoated and HSS Co coated by PVD process with TiN. On basis of these tests the cutting conditions optimizations were calculated for the minimum machining costs criterion using the basic economic indexes of the workshop. It was determined, that the use of more expensive HSS Co drills coated with TiN with longer cutting life yielded lower total production costs than the use of uncoated HSS drills. These lower costs were reached at higher cutting speed.

» Keywords: machining, twist drill, drilling, costs calculation at drilling


  • Constantin BUZATU, Adriana BĂLĂCESCU

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SURFACE ROUGHNESS MODELLING AT BALL BEARING RINGS SUPERFINISHING ON THE CUTTING FLUID AND PROCESS PARAMETERS INFLUENCE

INSTALLATIONS FOR INDUSTRIAL COMBUSTION OF WOODEN BIOMASS

» Abstract. The paper presents a possibility of surface roughness mathematical modeling in superfinishing on the process parameters and cutting fluid properties influence according with the friction coefficient between abrasive grains and workpiece surface. Starting on the assumptions of an abrasive grain model with spherical tip and assimilating the superfinishing process with broaching process, is obtained an equation of surface roughness parameter Rz according with the process parameters (t, sl, A, i.e. cutting depth, feed, amplitude of reciprocal motion of tool), oscillation radius R of tool, and respectively the friction coefficient between tool and workpiece by the cutting fluid characteristics.

» Keywords: superfinishing, roughness, cutting fluid, process parameters, constructive characteristics


  • Dumitru CATRINA, Adrian GHIONEA, George CONSTANTIN, Ionuţ GHIONEA, Hortensia BEZNILĂ

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ARCHITECTURE OF THE CNC HORIZONTAL LATHES

» Abstract. This paper presents a synthesis of the most recently types of parallel and revolver lathes in modular conception. The basic constructive variants are analysed and presented, pointing out their structure from the point of view of kinematic couples rotation (R) and translation (T), axes Z, X, Y, C, B and others, and motion axes numerically controlled. On their basis each structure is given a structural formula that contains the symbols of the NC axes connected to the tool and workpiece motions. Thus, one can distinguish between lathes with and without the axes C and Y, with one ore two coaxial or parallel main spindles, with one or two turrets, with or without radial slides, etc. The 2D and 3D representations regarding the architecture of the analysed lathes, lead to the establishing of a code that is assigned to diverse constitutive modules (structure elements, slides, revolvers, tailstock, heads with angular positioning adjustable o two axes, adaptable steady rest, system for storing and transfer of workpieces and tools, clamping and driving devices for workpieces and tools, chip conveyers). The variants in modular conception enable a rapid change of the analyzed machine tool configuration, depending on technological necessities of the types and complexity of workpieces to be machined, specific requirement of the flexible fabrication.

» Keywords: horizontal lathe, NC axes, generating/positioning motion, element, constructive assembly


  • Cătălin CHIVU

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STATIC MODEL AND SIMULATION OF A PNEUMATIC ARTIFICIAL MUSCLE

» Abstract. A Pneumatic artificial muscle (PAM) is a pneumatic device developed in the 1950’s as an orthotic appliance for polio patients by J.L. McKibben. It consists of a rubber bladder encompassed by a tubular braided mesh. When the bladder is inflated, the actuator expands radial and undergoes a lengthwise contraction. Present paper starts the research regarding PAM (pneumatic artificial muscle) by determining the static model of a PAM and testing this model by some simulations. The parameters resulted from the static model will be the input data for the dynamic model and, for the theoretical simulations, respectively .

» Keywords: pneumatic artificial muscle, static model, valve


  • Romeo CIOARĂ, Andrei CREŢUL

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SHEET-METAL EXPANDING MACHINE, WITH OSCILLATORY MAIN MOTION

» Abstract. The cinematic diagram of principle a machine-tool, particularly of a sheet-metal expanding machine allows the highlighting of mechanisms and structural elements the replacement or constructive optimisation of which represents an important means of innovation. Identical cinematic diagrams of principle can correspond to different solutions for the same type of machine, or even for different types of machines. In machines manufacturing, rotating, and in particular oscillatory motion is often easier generated and more favourable than linear motion. Hence it is preferable to design the working process as often as possible such as to include a rotating or oscillatory main motion and as many as possible of the other working and auxiliary motions. The paper proves the possibility of redesigning a sheet-metal expanding machine by replacing the linear alternating main motion by a self-returning oscillation, and by carrying out the corresponding required constructive modifications. While the cinematic complexity of the machine remains unchanged, the constructive and technological benefits are evident.

» Keywords: sheet metal expanding machines, oscillatory motion, cinematic structures, invention


  • Mihaela Elisabeta CIORTEA, Liviu MORAR, Adrian PISLA, Camelia VLAD

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PETRI-NET BASED APPROACHES TO FLEXIBLE MANUFACTURING SYSTEMS

» Abstract. This paper describes the planning process in flexible manufacturing systems. Flexible manufacturing system consisting of machines, computers, robots and automated guided vehicle. The skeleton and the functionality of a Petri Net Toolbox, embedded in the MATLAB environment, are briefly presented, as offering a collection of instruments devoted to simulation, analysis and synthesis of discrete event systems. The integration with the MATLAB philosophy responds to the general interest manifested by educators for enlarging the compatibility between the traditional background of Control Engineering applications and the novelty of discrete-event-systems scenarios. It explains a scheme of labelling and firing which makes modelling convenient for complex systems whose constraints are difficult to express only in terms of firing duration. The system manufacture choose is from the undertake S.C. APULUM S.A. Alba Iulia. Timed Petri nets are used to model operational and routing flexibility in production systems. A generalized multi-productive machine module is defined, adapted to system feature, repeated and connected to compose the TPN models of production systems with different levels of routing and operation flexibility.

» Keywords: Petri nets, manufacturing systems, MATLAB


  • Cristina COCULESCU, Corneliu COCULESCU

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NEW ORIENTATION IN PRODUCTION

» Abstract. Production complexity has imposed its place lately upon the enterprise and the passing through the morphological approach which identifies the stocking manufacturing places and the flows of goods, up to the definition of the manufacturing process. Nowadays, production tends to reoccupy it central place within the enterprise, from this it is resulted through a careful approach of the subject in the management colleges, in scientific literature, reevaluating the production system by the enterprises. Enterprise of XXIst century is no more essentially mechanic, however it has plenty of cars. This fact brings changes in industrial management wherein there is fortified a production theory relied on four concepts: static thinking, general bookkeeping, modular management and systemic approaching. In this paper deals whit the concepts on which the new production theory is based as well as the main features of the XXIst century enterprise.

» Keywords: production, statistical thought, accounting modular organization, systemically approach


  • Daniela COMAN, Anca PETRIŞOR

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FUZZY LOGIC CONTROLLER FOR SHOOTING ACTION OF AN INTEGRATED MULTI-AGENT ROBOT SYSTEM

» Abstract. An integrated multi-agent robot system for robot soccer games consists of multiple mobile robots, a vision system, a wireless communications system and a host computer. The multiple robots can be cooperatively controlled as they play a robot soccer game in an unknown and dynamic environment. The development of the system involved mechanism design and manufacture, integration of the electromechanical system, vision system, pattern recognition, decision-making, wireless communications, motion control and centralized coordination control. This paper proposes a fuzzy logic controller for shooting action which is one of the fundamental actions for soccer robots. The shooting action is view as a posture control problem with such a constraint that the robot should not approach the ball so that the ball moves to the home team area. The fuzzy logic controller consists of two levels: one is the planner level that generates a path to the ball with obstacle avoidance. The other is the motion control level that outputs robot wheel velocities to follow the desired path given the robot’s current posture. The effectiveness of the proposed fuzzy logic controller is verified by the simulation results.

» Keywords: fuzzy logic controller, integrated multi-agent robot system, path planner, obstacle avoidance


  • Sanda CONSTANTIN, Dana LUPŞA-TĂTARU

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EVOLUTIONS AND TENDENCIES REGARDING THE POPULATION LIABILITY RATE

» Abstract. The paper analyzes the evolutions regarding the population liability rate and the implication over financial stability. The population confronts with an increase of the risks determined by the expansion of the liability rate with its significant growth rate in the past years. It is presented the weight of population liability in GIP (Gross Internal Product). There are also explained the main factors of the population liability rate expansion, such as: the low level of population endowment with consumption goods, long term goods and real estates, the increase of people’s fortune and the available incomes, the improvement of macroeconomic conditions as well as the decrease of the interest rate in particular and in the last the role of funds transfer from residents who work abroad. Those factors are analyzed and presented with examples from Romania. At the end of the paper the conclusions relieved the impact of the increase of the population liability rate over financial stability.

» Keywords: liability rate, financial stability, real estates


  • Petru CRUCIAT, Flavius Aurelian SĀRBU

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ACCURATE EVALUATION OF THE ANGLES

» Abstract. The precision with which the conical parts that form adjustments are evaluated is unsatisfactory because of the limitations of the evaluation methods and of the measurement units of the plane angles. The second, the minute, the degree, the right angle, the radiant or their divisions are not usable because they are associated with unacceptable discrepancy for the parts that form adjustments. For using the advantages of the measurement units for lengths, we recommend the association of the conical surfaces with metrical configurations on the basis of some explicitly expressed criteria. We remind that in ancient times, geometricians expressed the angles with the help of the right-angle triangle, what we call today trigonometric functions. Their values are irrational numbers and the correspondence with the triangular configurations is difficult to establish.

» Keywords: angle, evaluation methods, measurement units


  • Tudor DEACONESCU

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STUDIES REGARDING THE PERFORMANCE OF PNEUMATIC MUSCLES

» Abstract. While compressed air is one of the most important energy sources in industrial drives, pneumatic drives tend to hold an increasing weight in the conception of modern industrial systems. Currently, the development of new pneumatic components and systems allows the achievement of high complexity assemblies, many of which with applicability in robotics. Such a component is the pneumatic muscle, its utilisation in the construction of pneumatic drives undergoing continuous development, particularly in the field of industrial robots. The paper presents some of the results of research carried out in the Fluidtronics Laboratory of the Regional Festo Training Centre established at the Transilvania University of Braşov. The experiments aimed at determining the variation diagrams of the feed pressure and the flow of consumed air for a complete cycle of the analysed pneumatic muscle. Further, the response times of the muscle could be determined for various values of the feed pressure, and the influence of adding a quick exhaust valve to the circuit on the response time for muscle deflation could be studied.

» Keywords: pneumatic muscles


  • Mariana DELIU, Gheorghe DELIU

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ON THE STATISTICAL ASPECT OF THE WIND POTENTIAL OF A LAND ZONE

» Abstract. The paper deals with the data processing method in the case of the evaluation of the wind energy of a land zone. Considering the wind speed as a random variable, the authors use the Weibull’s model for estimate the probability of the wind speed to take greater values than the inferior limit of the speed range a wind turbine needs in order to work in good conditions. After the theoretical features are presented, the application is made on a set of wind speed values measured at Sulina and presented by INMH in its web page. The results of present study gives to virtual investors a useful guide to the decision to take about the wind potential of a land zone utilisation.

» Keywords: random, wind speed, energy potential, estimation method


  • Dorin DIACONESCU, Ion VIŞA, Bogdan BURDUHOS, Valentina DINICU

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THE INCIDENCE ANGLES OF THE TRACKERS USED FOR THE PV PANELS’ ORIENTATION. PART I: EQUATORIAL TRACKERS

» Abstract. This first part of the paper presents the modeling and the simulations of the incidence angle of the (pseudo)equatorial tracker that is the angle between the sunray unit vector and the panel normal unit vector. At the same latitude, a comparison between the tracked PV panel and fixed PV panels is also presented. In order to realize this modelling, in the paper there are modeled the Sun-Earth angles and the two stated unit vectors. The paper’s results are useful in the (pseudo)equatorial trackers’ design.

» Keywords: solar panel, solar (pseudo)equatorial tracker, sunray unit vector, normal unit vector, incidence angle


  • Lubomir DIMITROV, Ivaylo KOVACHEV

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FRACTURE MECHANICS COMPUTER MODEL FOR THE CALCULATION OF THE CONTACT FATIGUE LIFE OF SPUR GEARS

» Abstract. The Fracture Mechanics approach is a relatively new approach used for the calculation of mechanical components fatigue life. In the paper presented a computer model, based on the fracture mechanics approach and on finite element analysis for determination of gear teeth fatigue life, is demonstrated. The model allows to follow the growth of a net of micro-cracks and their mutual interaction. It is considered that cracks initiate on the surface and finish on the surface. It is assumed, that the gear tooth contacting surface fails due to pitting when the size of pits increases 40 μm.

» Keywords: gears, gears tooth contact fatigue, fracture mechanics, crack propagation, finite element analysis


  • Adriana FOTA, Flavius Aurelian SĀRBU

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PLANNING STARTING FROM COMPUTER AIDED PRODUCTION MANAGEMENT

» Abstract. The issue of a director production plan allows getting a global idea concerning what it is feasible in an organization taking into account predictable requirements and available capacities. On the issue of this stage, the organization has a plan which must be applied in order to define precise fabrication and purchase orders. It is the net necessities calculation. Net necessities calculation or Material Requirement Planning (MRP) is an assembly of techniques using nomenclatures, supplies condition in order to generate fabrication and purchase proposals for the set of articles at all the nomenclatures levels starting from director production plan. Moreover, if there is the case, it supplies priorities among fabrication orders to be launched. It is a means of managing supplies. Today it is considered a planning instrument. Taking into account the volume of data and their numerous interactions, it is necessary to be used IT MRP soft in order to perform these calculations: this is a management pro soft for computer aided production management. In this work let’s illustrate the principle of necessary components through an example, an organization which assembles an industrial product and manages its production starting from a computer aided production management system based on MRP principles.

» Keywords: management, material requirement planning


  • Cristina GĂVRUŞ

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ECONOMICAL EFFICIENCY APPRAISAL OF THE NEW MODELS REGARDING THE SURFACE QUALITY FROM THE POINT OF VIEW OF THE PRODUCTIVITY OF THE CUTTING PROCESS

» Abstract. The present paper approaches some economical aspects regarding the new models of appraising the surface roughness determined by the author in some previous papers. One of these models refers to the case of turning with a cutting tool having a nose ray r and appraises directly the roughness Ra taking into consideration the working feed, s and the nose ray of the cutting tool. This paper proposes to determine the productivity of the cutting process taking into consideration the part of the lead time that depends on the cutting parameters and to appraise the productivity through the roughness Ra of the surface of the part processed through turning. The first part of the present paper establishes the theoretical aspects regarding the productivity appraisal, determining a mathematical model and the second part of the paper presents an application of the model, in order to evaluate the productivity of the turning process from the point of view of the roughness of the processed surface. As the roughness Ra depends on the working feed, the application is based on the statistic processing of some data regarding more values of the working feed, showing the variation of the lead time and thus of the productivity of the cutting process in accordance with the working feed. Briefly, the present paper highlights the importance of the new models of quality surface appraisal because they help for a rapid evaluation of the productivity of the cutting process.

» Keywords: productivity, working parameters, surface roughness, lead time


  • Petr HRABě, Milan BROˇEK, Rostislav CHOTĚBORSKŻ, Miroslav MÜLLER

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DEPENDENCE OF OVERLAY MATERIALS WEAR RESISTANCE ON THE LAYERS NUMBER

» Abstract. One of possibilities of parts functional surfaces betterment and in this way the service life prolongation is surfacing. Surfacing can be generally characterized as the formation of layers of special properties on metal surfaces. In this case it means the deposition of a filler material on the part surface using a suitable energy source (e.g. flame, electric arc) not only for renovation in order to reach the original dimensions, but for preventive overlays on new parts, too. In this case the reaching of suitable properties (e.g. hardness, stability to chemical attack, wear resistance) is the aim. The best use of this method of production is the use of such a technology which is the best above all from the point of view of working requirements and service life.

» Keywords: overlay materials, functional surfaces, abrasive cloth, abrasive wear, abrasive particles


  • Sųren Hųjmark JENSEN, Kristian Haahr JENSEN

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IMPLEMENTING OF LEAN MANUFACTURING IN SOME COMPANIES

» Abstract. The start-up phase is a decisive step to achieve success when implementing Lean in the company. The paper demonstrates how the implementation of Lean Manufacturing can be approached, illustrated by comparing and analyzing two distinct companies and their different approach to start-up the implementation of Lean Manufacturing. The two industrial companies are a small company employing 40 people and a medium sized company employing 630 people (40 to 50 people are employed in the present department).

» Keywords: Lean implementation, SME companies, motives and achievements, start-up procedures


  • Vladimir MĂRĂSCU-KLEIN

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THE APPLICATION OF CARBON MATERIALS IN ADVANCED TECHNOLOGIES

» Abstract. Innovation, often, takes the form of replacing a component made of one material (a metal, say) with one made of another (a polymer, perhaps), and then redesigning the product to exploit, to the maximum, the potential offered by the change. The engineer must compare and weigh the properties of competing materials with precision: the balance, often, is a delicate one. It involves an understanding of the basic properties of materials; of how these are controlled by processing; of how materials are formed, joined and finished; and of the chain of reasoning that leads to a successful choice.

» Keywords: material, properties, redesign


  • Laurenţiu MIHAIL

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ROBUST OPTIMIZATION OF THE PERPENDICULARITY DEVIATION FOR THE DEEP HOLE DRILLING PROCESS ON FLEXIBLE MANUFACTURING SYSTEMS

» Abstract. The present paper presents a part of a research project, developed in a plant of a multinational supplier from the automotive industry. The need to do those researches was born from the fact that a relatively new type of material (a composite, polypropylene material) was machined on a high speed flexible manufacturing system. For this type of materials, in the technical literature, there are not recommendations for the cutting parameters. Using the Taguchi’s Method, for this approach, was a very good idea because, spending the smallest amount possible of resources, there were obtained the desired results. So, in other words, the efficiency was the biggest possible. Practically, in the present industrial trends, that is the target – to obtain maximum efficiency, not only maximum efficacy.

» Keywords: robust engineering, efficiency, machining, composite materials, design of experiments


  • Constantin MINCIU, Andrei Petre SEBE, Dumitru CATRINA

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CONTOUR MACHINING OF SOME COMPLEX CURVES

» Abstract. This paper presents an example of complex curves machining which covers the range of contour machining in 2 axes on numerically controlled machine tools. All utilized software was generated based on original Pascal, AutoLisp and TCL files, being implemented the studies and algorithms presented in [5].

» Keywords: medial machining, contour milling, software, commands


  • Daniela Cristina MOMETE

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THE TRINOMIAL SUSTAINABLE DEVELOPMENT – ECONOMIC GROWTH – ENERGY IN EUROPEAN CONTEXT

» Abstract. This paper has in view the emphasis of the importance of energy for human development and economic growth, but also its impacts on sustainability. In a trinomial approach, it concisely presents the negative effects of energy consumption on environment, and at the same time its positive effects on economic growth. In a pursuit to identify overall effects of energy, the energy consumption is correlated with the economic growth and CO2 emissions, by using energy and CO2 intensities, at the European Union level, taken into comparison with the rest of the world. The paper argues that sustainable development must be perceived as another dimension of the economic growth that can be only achieved by a sustainable energy production and use.

» Keywords: sustainability, economic growth, energy intensity


  • Liviu MORAR, Dumitru POP, Adrian PISLA, Camelia VLAD

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ON THE POSSIBILITY OF IMPROVING THE WIND GENERATORS

» Abstract. The article proposed an algorithm for generating sets of blades used for wind generator’s propeller. The main goal is to design and realise a 1 kW wind generator that can work with high efficiency at the specific wind condition from Romania. Since a big amount of time the wind speed is lower, usually less than three m/s it was designed a propeller that has a starting speed of 2.7 m/s. A low Reynolds number airfoil is selected regarding to the low working speed of the propeller’s generator. This airfoil is considered the reference. Based on the airfoil, the necessary calculations are made in order to obtain all the points that will form the blade. It was analysed the influence of tip speed ratio, lift coefficient and attack angle upon the blade profile and generate two sets of blades. A Pascal software was written with which can directly build the NC files. In order to correct the influence of the radius of the cutter upon the final shape of the blade, was also implemented a procedure that will adjust the initial coordinates. For machining the blades a CNC milling machine was designed and realised.

» Keywords: wind generator, propeller, blade design, CNC milling machine


  • Cristina Ileana PASCU, Iulian POPESCU

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PROBLEMS ABOUT TOLERANCES AT THE KINEMATICS GENERATION OF POLYHEDRAL SECTIONS BASED ON THE HYPOCYCLOIDS

» Abstract. For this study it has started from generation principle of polygons on the basis of cyclic curves. This research presents tolerances and processing accuracy by turning of some surfaces with polyhedral sections. Hypocycloids are generated that on the middle zone approximate straight lines belong to polyhedral sections. Analogous, the precision at a square generation has been studied establishing that the deviations are bigger than at the hexangle generation. Examples for obtained curves are presented and the deviations given theoretical section are evaluated. Thus, the processing of pieces with polyhedral sections is very productive and the resulted accuracy is into tolerated heights limits.

» Keywords: hypocycloid, upper deviation, tolerance, polyhedral turning


  • Horia Liviu POPA, Liana Rodica PATER

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THE CLUSTER’S COMPETITIVENESS ANALYSIS

» Abstract. In the last two decades the growth of national economies competitiveness was mainly based on regional development and growth of regional clusters competitiveness. The development of a new “integrative competitiveness management for clusters” and of the basic structural-functional models in this transdisciplinar area is a priority in Romania and European Union. The purpose of the paper is to contribute at the development of systemic model and method of competitiveness analysis, useful for the radical / continuous improvement and optimisations of the companies and clusters performances. The managerial analysis of cluster’s competitiveness (AKC) is a new, original, complex, dynamic quantitative analysis method and a stage of the integrative cluster’s competitiveness management. The implementation of the cluster’s competitiveness analysis and of integrative management for clusters will assure the competitiveness increase at micro, mezo and macro levels.

» Keywords: cluster, competitiveness, competitiveness analysis


  • Radu Cristian POPESCU, Gheorghe OBACIU

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MAINTENANCE STRATEGIES USED IN INDUSTRIAL PLANTS

» Abstract. Strategy in maintenance: changing from a complete in-house solution up to complete outsourcing showing how to analyse and develop a strategy. Components of a strategy are revealed in order to clear things before they get started. The article contains original contribution in synthesizing the strategic thinking in a combination, to be cost-effective and having the best results in Uptime.

» Keywords: strategy, outsourcing, contract maintenance


  • Radu Dumitru STANCIU

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MASLOW APPROACH IN DESIGNING JOB OFFERS

» Abstract. In a market economy, the success and stability of a company depend on the way its resources (materials, finance, information, technology, energy, employees) are used. Because of their importance, the human resources activities need a special consideration. The paper presents a possible approach to the work offer based on Maslow theory.

» Keywords: job offer, motivation, Maslow theory


  • Eugen STRĂJESCU, Ileana FULGA

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THE VISUALIZATION OF THE FLUIDIC FLUXES IN THE MILLS WITH JETS

» Abstract. The visualization of the fluidic jets, as they appear in the mill with spiral jets is essential for the understanding of the physical phenomena that are at the base of the micronization of the particles of all nature (metallic carbides, ceramics, cosmetics, and pharmaceutics). In the paper is shortly presented the necessary drives to realize this demarche, inclusive some experimental results that acknowledge their correctness and their functionality. The obtained information is essential for the elaboration of a mathematical-physical model of the fluidic mills with spiral jets.

» Keywords: fluidic mills, spiral jets, microphotography, mathematical model of the mills


  • Mihaela VARTOLOMEI

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THE RELATIVE ADVANTAGE THROUGH ROMANIAN EUROPEAN INTEGRATION PROCESS

» Abstract. In this work, the author wants to approach the Romanian European integration problems, from opportunity cost vision, studying the cost of the best sacrificed alternative for achieving the integration process, as chosen variant. Starting from competitive advantage concept, a link between the strategic management and international economy, than using the relative (comparative) advantage principle, using the production possibilities border, in the framework of this work we make a comparative study of integration process, in order to research if the integration process has a lower opportunity cost comparing with the other removed alternatives. Does the opportunity cost come before the convergence cost? It is possible a convergence (economic, structural, legislative, juridical, social, nominal convergence)? If the answer is positive, which is the cost of it? How will the asymmetric shocks influence this convergence? How will look the work division and Romanian specialization after the integration process? Which would be the gained and the bankrupt sectors after the EU integration? In order to obtain partial and general answers, we make a comparative analyze of the economic structure, using economic aggregates, the economic, social and commercial policies of the EU and the main indicators of the convergence criterions.

» Keywords: SolidWorks, metal platforms, Weldments module, Sheet Metal module


  • Sorin VARTOLOMEI, Mihai JĂDĂNEANŢ

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THE MANAGEMENT OF MILITARY TECHNICAL, TECHNOLOGICAL AND MANUFACTURING SYSTEMS

» Abstract.The military establishment is one of the most important institutions to configure a credible system for the state’s national security and also for regional and world security. The paper proceeds with a description of the technical, technological and production systems: the origin, the components’ nature, the action systems hierarchy. The general-functioning structure of an integrated system of production. The military establishment – an integrated system of production. The nowadays trends in the most of the world’s armies have had an influence on Romanian military system too: a fundamental change of organizational structure and of managerial practice, in particular as a consequence of abandoning the mass army model and also a development of military techniques and technologies. The Romanian army efficacy has as a final aim the accomplishing of a structure of force more compact, efficient, with more performance, flexible and compatible with NATO’s standards, and in this framework will be created the structure of forces and will be insured the fighting techniques modernization, through a process of differentiating the military institutions by the civilian institutions and also through the process of creating a professional and complete military staff, both from technical and technological endowment point of view and also from the human resources. A competitive management of an efficient army has to be able to insure in every moment the unfolding of land troops in the theatre of war, super trained and super endowed with the newest „high-tech” equipments.

» Keywords: technical system, technological system, manufacturing system, integrated systems of production, Romanian army technique efficiency


  • ION VIŞA, DORIN DIACONESCU, VALENTINA DINICU, BOGDAN BURDUHOS

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THE INCIDENCE ANGLES OF THE TRACKERS USED FOR THE PV PANELS’ ORIENTATION. PART II: AZIMUTHAL TRACKERS

» Abstract. Firstly, this second part of the paper models and simulates the azimuthal PV tracker incidence angle variations. On the basis of the numerical simulations, there are presented a comparative analysis of the incidence angle variations obtained with the two tracker types (azimuthal and pseudoequatorial) and the main conclusions derived from this analysis. The results are very useful in the tracker’s design.

» Keywords: incidence angle, azimuthal PV tracker, pseudoequatorial PV tracker, solar angles


  • Snejana YORDANOVA, Lubomir DIMITROV, Dimosthenis MICHALOPOULOS

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SIMULATION MODEL OF INVESTIGATION OF CRACK GROWTH PROCESS IN FIGHTER STRUCTURAL COMPONENTS

» Abstract. In the present paper the use of modern approaches towards the evaluation of the reliability and strength of randomly loaded components are examined. A fighter airplane during flight operation is examined and its structural components (body, wings and tail) are loaded with randomly varying forces. A MATLAB environment model based on Fracture Mechanics Approach, and employing “Monte Carlo” stochastic methodology for determining the strength of these components was devised. The simulation model determines the time between two consecutive maintenances and to guarantee the pilot’s safety during the exploitation of the fighters. By the use of this model, simulation on the reliability of different aircrafts could be made. The only requirement is to have enough and reliable input data.

» Keywords: simulation modeling, crack propagation, fracture mechanics, “Monte Carlo” method, MATLAB


CONTENTS


No. 3 (21 b)


  • Ruxandra-Gabriela ALBU

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SUSTAINABLE TOURISM DEVELOPMENT MANAGEMENT IN THE BRASOV REGION

» Abstract. Beside other economy sectors (such as agriculture), tourism represents an economic activity which directly depends on the undertaking of a sustainable management. No tourist wants to spend its holiday in a polluted environment, unattractive or with a hostile population. Tourism focuses on issues which are special, beautiful, valuable or unique. Thus, tourism highly depends on preserving the natural beauties, on the hospitality and the positive attitude of the local communities. The beneficiaries of the tourism activities should not only be the tourists and those who directly work in tourism but also the whole population of the region, which could take advantage of the effects of the tourism development, such as: general infrastructure modernisation, working places offer increase, life quality improvement etc. Tourism could facilitate the processes of attitude and mentality changes and in the meantime contributes to a better cooperation and understanding between people and regions. The paper intend to demonstrate that tourism could become an undisputable model of sustainable management strategy, and the actors involved in the tourism activity should be directly interested in its implementation.

» Keywords: management, sustainable, tourism, strategy, region


  • Diana BĂRGLĂZAN

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EXCHANGE RATE APPRECIATION AND EXTERNAL TRADE SUSTAINABILITY: THE CASE OF ROMANIA

» Abstract. In most Central and Eastern European Countries, during the last 10 years, the real exchange rate appreciated. In the countries having adopted a flexible exchange regime, nominal exchange rate appreciation was a common phenomenon. Recently (starting with October 2004), this tendency could be observed even in Romania. Although considered a normal phenomenon, caused by the catching-up process, the exchange rate appreciation is feared in all countries, as it favours importations and slows down exportations, jeopardizing the sustainability of the external trade balance and having a negative impact on the national competitiveness. In this paper, the correlation between the exchange rate evolution and the dynamics of external trade is investigated, for Romania. The analysis tries to find some support for the fears expressed by the Romanian exporters regarding the appreciation of the leu toward the euro and for the accusations addressed to the national bank of Romania, concerning the exchange policy. All arguments considered, including the liberalization of capital movements, the decision of the National Bank of Romania, to let the leu float more freely on the exchange market, seems to be justified.

» Keywords: exchange rate appreciation, external trade, national competitiveness


  • Nicolae BOIAN

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DIAGNOSTIC OF ACTIVITIES TO SMALL AND MIDDLE SIZE COMPANIES

» Abstract. The paper presents a model of activities analyze to small and middle size companies, based on strategic segmentation method according which, each activity is evaluated by its contribution to society patrimonial fortune. The objectives of diagnostic analyze is to evaluate all companies activities by contribution to general value and by integration ratio into global companies strategy. The proposed model take account the booth type of factors: internal and external specific to small and middle size company due by diversity of activities and resources partition. The three main steps in analyze are: determination of “key success factors” (KSF), which enforced the activities competition position, followed the regrouping in “strategic activities domain” (SAD), that use common factors and “strategic base” (SB) which share same resources. Based on these determinations is built the “strategic activities map” that allow to divide resources into maximum efficiency conditions. Model proposes a general plan of analyze, developed on stages, making evident the necessary work instruments. Finally paper present an example of diagnostic to a small package factory. Conclusions refer to implication of analyze results on company’s management strategy.

» Keywords: competition, competitive forces, evaluation, determinant factors, process, pressure forces


  • Gheorghe BONCOI, Magdalena BARBU

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FORWARD-LOOKING GRAPHICAL-ANALYTICAL MODEL DEVELOPED TO FORECAST THE TECHNICAL-ECONOMIC ENVIRONMENT IN MANUFACTURING HEAT-INSULATION CARPENTRY

» Abstract. The paper presents the fundamental relations of the model and the main graphical models of the seasonal production. There are presented the calculation relations of the production volume developed on physical and value basis, in the present, past and future, taking into account the probabilities and assumed risks, on seasons, in product manufacturing and total production, the share of the product in product manufacturing and total production. Similarly, five graphical models of the seasonal production and two histograms are presented, resulting in the development tendencies of the production and its dynamics. The increase in the manufacturing rate is defined on season and the coefficient of the share of the product in global, seasonal and annual production is also defined.

» Keywords: mathematical model, technical-economic environment


  • Gheorghe BRĂTUCU, Ionuţ CĂPĂŢĪNA

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CONTRIBUTIONS TO THE RESEARCH OF THE DEGRADATION COMPONENTS FROM AUTOMATION SYSTEM TOOL-MACHINE

» Abstract. In the work is tackle the problem of components degradation of the automation systems from tools-machine, for which the experimentally researches has been made on two lots of 12 lathes with digital commanding. To these the elements of automation ware predominated hydraulic (the variant 1) or electric-electronic (the variant 2). The study of these in exploitation has been made on a period of 5 years (the precinct 20000 working hours), which permitted the obtained of a sufficient date of precise in bind with the way, the periodicity and the causes of components degradation. Through the statistical analyze of collected dates they established the weights of different types of equipments and automation equipments innards. Between two types of automation equipments are manifested sensitive differences below the appearance of brake downs frequency, this being much littler at the electric - electronic components comparative with the hydraulic one. The hydraulic brake downs represent 66.6 % to the variant 1, and electric-electronic brake downs represent just 5.81 % to the variant 2, while to the components mechanical the structure and break down frequency its kipped constant. To the mechanic components the brake downs are caused by the surfaces usage (51.7 %), the degradation of the innards deeply (32.8 %), functional brake downs (11.6 %), etc.

» Keywords: tool-machine, degradation, wears


  • Constantin BUZATU

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THE INFLUENCE OF THE TECHNOLOGICAL AND CONSTRUCTIVE PARAMETERS OF THE TOOL SYSTEM ON THE SURFACE ROUGHNESS AT BALL BEARING RINGS SUPERFINISHING

» Abstract. Starting from the mathematical modeling of surface roughness after machining, in the paper is presented some theoretical points of view, based on graphical dependence, regarding the influence of different process parameters, less recorded in the literature, on the roughness variation. In this sense it is shown the important influence of a cutting fluid quality, by the friction coefficient between the abrasive grains and workpiece surface. Based on the graphical dependences that were made for the typical machining conditions often used in superfinishing practice it is analyzed and is taken in evidence the influence of the friction coefficient between the abrasive grain and workpiece surface, established by the structural characteristics of the cutting liquid and by its inpure degree, elements that wasn’t examined in the literature.

» Keywords: superfinishing, ball bearing, cutting fluid, friction


  • Catrina CHIVU

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DYNAMIC MODEL OF A PNEUMATIC ARTIFICIAL MUSCLE

» Abstract. The pneumatic artificial muscles are pneumatic actuators used, during last years, especially in prosthetics (used to model a joint of a limb or to substitute the muscle of a limb – especially the lower limb). The main problem that appears is the control of the PAM. To be able to create a control system it should be done first the static model, then the dynamic model and, using the values obtain from these models, can be designed the control system. The present paper presents the dynamic model of a PAM and is part of an elaborated work that starts with the static model and it will end with the control model and design of an experimental stand.

» Keywords: pneumatic artificial muscle, dynamic model, control, simulation


  • Rostislav CHOTĚBORSKŻ, Miroslav MüLLER, Petr Hrabě, Milan BROˇEK

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PROPERTIES OF MARTENSITIC OVERLAY MATERIAL

» Abstract. The abrasive wear resistance of martensitic overlays is the function of many variables. The hardness is one of the variables. This fact is raised by the possibility of carbidic phases separating from the austenite in the course the overlay layer cooling and by the possibility of the further martensite disintegration and carbidic phases precipitation. The paper is engaged in the hardness and abrasive wear resistance problems of one-layer and two-layer martensitic overlays material.

» Keywords: welding, overlay material, abrasive wear


  • Cristina COCULESCU, Radu DESPA, Ovidiu FOLCUŢ

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NEW PARADIGMS OF ENTERPRISE

» Abstract. New enterprise, characterized of integration, virtualization, globalization, of the need of whole life cycle consideration and technological sophistication (including what concerning the informatics system) is a more complex system than that of industrial systems, self-driven of ’80 years. Industrial Informatics System (IIS) has traditionally approach pure technical aspects of technological processes which are developed in equipments, engineering creations. Additionally, the interesting range of IIS was generally well bordered in time and space and the links to other kind of works have in the best case considered as „external factors” if they have been ever ignored. At present, it tries the placement of IIS in enterprise context which suffers a series of important changes. Main external causes which have action over the changing of industrial informatics system come from the enterprise itself wherein the system is put in and wherewith it joins and, finally, into the environment (of market, law, social, natural) wherein it operates. In the last years, there was observed an important tendency of enterprise management in a form very like that of live or social systems. In this paper, there will be shown some of the aspects appreciated as important for conception and computerization of new kind of enterprises, with special references to the new paradigms of enterprise. Viewing the dynamic of this domain wherein absolute accepted solutions for understanding the sense of evolution of implied actors and results aren’t reached, the presentation will contain many elements of „history”.

» Keywords: the new enterprise, the integration of the industrial enterprise, extended, virtual, holonical enterprise


  • Petru CRUCIAT, Flavius Aurelian SĀRBU

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BEARING PERCENTAGE OF THE SURFACES

» Abstract. The natural wearing out process as well as the elastic deformations because of the contact compression between parts, diminish a great deal the surface we can rely on. If we analyze only two typical cases: the profile alike to letter m and the profile alike to letter w, for the bearing percentage for p = 50% in the first case, Tp is much bigger than 50%, and in the second case, it is much smaller than 50%. The “m” profile behaves well when lubricated (does not tear the lubricant film), but it is dangerous for the parts variably stressed (the abysses are primers of cracks favoring the tear when repeatedly compressed and stretched). On the contrary, the “w” profile is not indicated for lubrication (the points will go through the lubricant film), but it behaves very well when variably stressed.

» Keywords: surface, bearing percentage, profile


  • Andrea DEACONESCU

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ROBUST DESIGN – A DECISION MAKING TOOL IN MACHINING BY LAPPING

» Abstract. The paper presents a computer-based intelligent decision support system designed to achieve the optimization of the lapping of plane surfaces, by the Taguchi’s method of arrays of experiments. The steps to be followed for solving the issue of optimization are described, the most important ones concerning the defining of the targeted objective, establishing the factors influencing the process and their respective levels, selection of the optimum array of experiments, processing of the results and determining the optimum configuration of the levels of the considered factors.

» Keywords: arrays of experiments, computer-based intelligent decision support system


  • Tudor DEACONESCU

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REGIONAL TRAINING CENTRE FOR PNEUMATIC AND HYDRAULIC DRIVES

» Abstract. The degree of complexity and refinement of fluidic drives has known a permanent growth, requiring the existence of an adequate training system of staff working with pneumatic and hydraulic equipment. The updating of knowledge related to fluidic drives and automation has become a necessity of high priority, calling for an increased frequency of personnel training sessions. The paper presents the achievement within the Transilvania University of Braşov of such a training facility in the field of fluidic drives and automation. The structure of the Regional Training Centre for electro-pneumatic and hydraulic automation is presented, as well as the delivered course modules and the state-of-the art endowment of the centre.

» Keywords: pneumatic and hydraulic drives


  • Mariana DELIU

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A SUGGESTION OF NEW CLAIMS IN TOOL QUALITY STANDARDS

» Abstract. The necessity of some modifications in the tool quality standards, regarding the claims about tool reliability, is motivated in the present paper. In this sense, the author demonstrates that the most suitable model for reliability indicators estimation of the cutting tools is the two-parameter Weibull model. On the basis of some cutting tests, the author indicates the mode in which the change of cutting conditions during the tests does influence the reliability model parameters.

» Keywords: cutting, tool, reliability, quality, standards


  • Monica FLORESCU

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NANOTECHNOLOGIES FOR ENZYME-BASED BIOSENSORS

» Abstract. Inorganic and organic hybrid nanomaterials are a fascinating research area, due to the highly promising potential for versatile properties provoked by combining the merits of both sources and by the nanometer size effect, which is entirely different from that in a bulk material. Moreover, a coupling of biorecognition elements on nanostructures might allow a creation of functional hybrid systems with molecular-scale proximity between the molecular recognition and transduction element. Environment, molecular biology, medicine and other life sciences require for a new class of devices having a fast sensitive and reliable response for investigating biomolecular interactions. This need has fuelled a revolution of a new class of sensors, biosensors that are the product of the integration of nanotechnology, biology, and advanced materials. The possibility to employ new materials and innovative technologies allows realizing conceptually new devices, potentially competitive to the existing in classical technologies. The sol-gel encapsulation of biomaterials and organic complexes has recently seen important developments, sol–gel being an interesting and versatile way to prepare modified electrodes and biosensors.

» Keywords: sol-gel nanostructure, glucose oxidase enzyme, electrochemical biosensor


  • Adriana FOTA, Flavius Aurelian SĀRBU

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PRODUCTION MANAGEMENT THROUGH ENTERPRISE RESOURCE PLANNING (ERP) INSTRUMENTS

» Abstract. Adopting IT tools or IT systems in companies is explained through the research of a global vision of production systems and the wish to improve the transmission speed and information coherence. These ERP (Enterprise Resource Planning) permit the coverage of the functional necessities of the company. They are characterized by a real time management, a synchronization of the physical, financial and accountability fluxes treatment and the exploitation of coherent data because of multidimensional data bases. Implementing an ERP can be a complex project from the point of view of time and cost, involving as well collaboration within a project team. In this paper will be presented the methodology of implementing an ERP and the effects of applying ERP can be analyzed through function. Sometimes, ERP is based on a capitalization of the most proficient processes, identified by those who have conceived these instruments, what makes them attractive for companies, bringing them international benchmarking elements. Moreover, the conception of an information system becomes a process which corresponds to a situation by required configuration.

» Keywords: management, planning production, logistic


  • Ileana FULGA, Eugen STRĂJESCU

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THEORETIC AND EXPERIMENTAL CONTRIBUTION CONCERNING THE MEASUREMENT OF THE FUNCTIONAL PARAMETERS OF THE FLUIDIC MILLS WITH SPIRAL JETS

» Abstract. This writing analyses the theoretic bases necessary for the optimisation of this type of mills and presents the results of the experimental researches, which permits the elaboration of a mathematical model able to describe correctly the flow of the compressed air and of the particles inside the mill. It is also presented the experimental apparatus and the mode to determine the speeds in different points of the flow section and the apparatus used for the acquirement of the data and their interpretation and visualization.

» Keywords: fluidic mill, spiral jets, micronization, speed of the fluid jet


  • Liviu GACEU

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ASPECTS REGARDING THE DESIGN OF THE PORTABLE MOWING MACHINES, USING THE FINITE ELEMENTS METHOD

» Abstract. The vibrations produced in the operating state of portable mowing machines have notable effects on the human organism, and has to be reduced as much as possible, starting from the design stage. The papers proposes a modelling method with elements finite (using I-DEAS SDRC software), which allow the topological optimization of these equipments. The model calculates the first four resonance frequency, the shape of the tool in these duty points, as requirements elements for settlement of the nominal working stage. In the last part of the paper, it is considered a case of impact between a hard body and the cut-off device, studying also the behaviours of the elastic structure and its impact on human body.

» Keywords: vibrations, portable mowing machines, finite element


  • Cristina GĂVRUŞ

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ECONOMICAL EFFICIENCY APPRAISAL OF THE NEW MODELS REGARDING THE SURFACE QUALITY FROM THE POINT OF VIEW OF THE COSTS OF THE CUTTING PROCESS

» Abstract. The present paper continues the series of papers published by the author regarding the importance of some new mathematical models presented in some previous papers. Concretely, this paper approaches the economical aspects of the cutting process from the point of view of the costs involved, trying to determine the influence of some cutting parameters upon the costs of the cutting process and to establish the cost of the cutting process taking into consideration roughness Ra of the surface processed. Within the papers mentioned above the author determined two new mathematical models for appraising roughness Ra, unlike the specialized literature that presents some models regarding roughness Rmax or Rz. It is very important to have a mathematical model that refers to Ra roughness because this type of roughness appears on all working drawings and to pass from other types of roughness to Ra could be subjective and uncertain. The mathematical model refers to the case of turning using a nose ray cutting tool. The present paper starts from the mathematical model of appraising roughness Ra and has two important parts. The first part presents a mathematical model regarding the costs of the cutting process and the second part shows an application based on statistical processing of some data, regarding some cutting parameters and analyses its influence upon the economical efficiency expresses through the costs of the cutting process.

» Keywords: economical efficiency, costs, cutting feed


  • Radu GĂVRUŞ

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ANALYSIS OF COMMUNICATION SYSTEMS AT DATA LINK LAYER

» Abstract. The present paper takes part from an enhanced scientific research developed by the author of this paper, which aims the hardware implementation of a reconfigurable system at data link level for communication on a structure of FPGA (Field Programmable Gate Array) type. The present paper approaches OSI-RM (Open System Intercommunication – Reference Model) System, which is an International Standard, especially the level number 2, OSI no.2. The paper also presents some aspects regarding the form of data frames, and a conceptual view of hardware architecture related to the data link layer (OSI – layer 2). Within the paper, the author also makes an analogy among the forms of different communication standards: 802.3, 802.4 and 802.5. The reason for doing this is that converging towards a unique standard or diminishing the number of protocols is very unlikely. The dynamic of the communication field and the market demand will determine in the near future the development of new standards, protocols, networks and services that are very different from the actual once.

» Keywords: data link layer, OSI, FPGA, communication


  • Luminiţa GRECU

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USING SHORT STUBS FOR MATCHING THE IMPEDANCE OF A LOAD TO THE IMPEDANCE OF A TRANSMISSION LINE-ANALYTICAL SOLUTION AND COMPUTER CODE

» Abstract. This paper presents an analytical solution and a computer code for solving the problem of how to match a load impedance to the impedance of a transmission line using three short stubs. Matching the impedance of a network to the impedance of a transmission line is necessary first, because it makes all the incident power to be delivered to the network, and second, it is necessary for a better behave of the generator, because, usually the generator is designed to work into an impedance close to common transmission line. In this case the load impedance has no reactive part which can pull the generator frequency, and the SWR on the line is close to the unity, so the line connecting the generator to the load is non resonant. Stubs are used for producing a pure reactance at the attachment point, reactance that varies with their length. For matching any impedance load to the impedance of the transmission line 3 stubs, that have fixed positions on the transmission line, can be used. This paper is focused on how to determine their lengths for solving the problem of matching the impedances. An analytical solution of this problem is given and, based on it, a computer code in MATHCAD is developed too. The computer code offers the lengths these stubs must be regulated to, when the load impedance and the impedance of the transmission line are known. There exist four such solutions, so four combinations of lengths, and the computer code gives all these solutions.

» Keywords: short stubs, transmission line, impedance, matching impedance


  • Adela IONESCU, Mihai COSTESCU, Daniela COMAN

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A COMPUTATIONAL APPROACH OF TURBULENT MIXING. THE TRAJECTORIES ANALYSIS

» Abstract. A competent manager wishes to have available in every moment the necessary information on the state of the system he or she is managing. The manager’s efficiency emerges from the rightness of his/her decisions taken in an optimum time range, and from the efficient allocation of the available resources. Tracking the efficiency indices' evolution leads to the best solutions to everyday problems. A useful instrument at the foundation of modern management is the scoreboard. The paper presents the conception method and the utilization algorithm of the maintenance management’s scoreboard by dependability breakeven points.

» Keywords: scoreboard, dependability, reliability, maintainability, security, availability, breakeven points


  • Mircea IVĂNESCU, Mihaela Cecilia FLORESCU

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ON THE DISTRIBUTED CONTROL FOR THE COIL FUNCTION OF A TENTACLE ROBOT

» Abstract. The paper focuses on the control problem of a hyperredundant robot that performs the coil function of the grasping. First, the dynamic model of a tentacle arm with continuum elements produced by flexible composite materials in conjunction with active-controllable electro-rheological fluids is analysed. Secondly, both problems, i.e. the position control and the force control are approached. The difficulties determined by the complexity of the non-linear integral-differential equations are avoided by using a very basic energy relationship of this system. Energy-based control laws are introduced for the position control problem. A force control method is proposed, namely the DSMC method in which the evolution of the system on the switching line by the ER fluid viscosity is controlled. Numerical simulations are also presented.

» Keywords: distributed parameter systems, grasping, tentacle robots, and force control


  • Codruţa JALIU, Dorin DIACONESCU, Radu SĂULESCU

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KINEMATICAL AND DYNAMIC PROPERTIES OF A SPEED MULTIPLIER USED IN WIND TURBINES

» Abstract. Representative kinematical and dynamic aspects of a planetary speed multiplier for wind turbines are presented in the paper: analysis of the transmission ratio and efficiency and analysis of the dynamic response in a relevant functioning case.

» Keywords: speed multiplier, multiplying ratio, wind turbine, kinematical analysis, dynamic response


  • Badea LEPĂDĂTESCU, Adela-Eliza DUMITRAŞCU, Ioan ENESCU

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ESTABLISHING PARAMETERS THAT INFLUENCE THE LENGTH AND SHAPE OF THE ABRASIVE GRAIN PATH AT TRAVERSE SUPERFINISHING

» Abstract. The paper presents the parameters that influence the length and shape of the abrasive grain path at traverse superfinishing. Starting technological parameters of the superfinshing process are mathematical modelled the equations which show the trajectory of to the abrasive grain on the workpiece surface during the superfinishing machining for two types of the reciprocationg motions of the tool system: on with low frequency for roughing and other with high frequency for finishing. The final equations of the grain trajectory are dependent of the machining parameters and constructive characteristics of abrasive tool.

» Keywords: surface finish, production rate, parameter, attachments


  • Georgiana LIMBĂŞAN

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THE RELATION BETWEEN SOCIAL NECESSITY, QUALITY CHARACTERISTICS AND THE FUNCTIONS OF THE PRODUCTS

» Abstract. Quality of a product is one of the important factors which determine the product’s success on the market. Quality means conformity with needs, with the social requirements at a certain moment. Quality is obtained through quality characteristics: technical, economical, functional, aesthetic and social characteristics, which are identified in different existence stages of a product. The quality characteristics are realised through different features (physical components) of a product. These features fulfil one or many functions, which give the product value (use value). The paper emphasis these aspects, illustrate he relation between quality characteristics and functions on the “bearing” product.

» Keywords: quality, quality characteristics, functions, product


  • Dana LUPŞA-TĂTARU, Sanda CONSTANTIN

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KNOWLEDGE-BASED ECONOMY, SUSTAINABLE DEVELOPMENT AND INFORMATION TECHNOLOGIES

» Abstract. Within the, new economy knowledge is a strategic resource for post-industrial organisations, recognised as the driver of productivity and economic growth, leading to a new focus on the role of information, technology and learning in economic performance and determining the efficient and environmentally use of the other resources. Considering the role of information and communication technologies in the new economy as means for knowledge management processes within knowledge management systems, the bound between knowledge-based economy and sustainable development, the analyze of the use of information and communication technologies in different countries, over time and through comparison with the high human developed group, is very up-to date. The paper focuses on comparisons between Romania and other countries based on two indexes defined by World Bank, KEI – knowledge-economy index – and KI – knowledge index, and also based on the three key variables as proxies for knowledge-based economy. The paper also presents the evolution of Romania’s KEI and KI over time and its main accomplishments in the field of ICT.

» Keywords: knowledge-based economy, ICT, sustainable development


  • Ionel MARTINESCU

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CONSIDERING ON THE IMPORTANCE OF ELEMENTS OF THE SYSTEMS WITH SERIES

» Abstract. The paper presents the quantitative evaluation of the importance of the system’s elements with series structure, taking into account two cases of specification of reliability parameters: constant; time dependent. The exemplification of importance of elements is done using charts and tables, considering a system with series connection of 3 elements.

» Keywords: system, reliability, series


  • Laurenţiu MIHAIL

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ROBUST OPTIMIZATION OF THE CYLINDRICITY DEVIATION FOR THE DEEP HOLE DRILLING PROCESS ON FLEXIBLE MANUFACTURING SYSTEMS

» Abstract. This article is a presentation of an application for the Robust Engineering concept, applied on the manufacturing of the composite materials, on Flexible Manufacturing Systems, at high speeds and feeds. The deep hole drilling with helical drills is a difficult machining process because of the chips that must be evacuated from the machining area, but not only. This is a more complicated action if it is machined a sort of material as is Necuron. So, it must be used peck drilling. The problem that appears it the cutting parameters, that doesn’t exists in the branch literature, explicitly.

» Keywords: problem solving, coordinate measuring machine, ISO TS 16949:2002, design of experiments


  • Georgeta Emilia MOCUŢA, Eugen GHITA

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THE ANALYSIS OF THE TRANSHIPMENT CAPACITY OF AN INTERMODAL TERMINAL

» Abstract. The paper deals with a presentation of the main requirements of the intermodal network and transshipment capacity mathematical calculation in an intermodal transportation terminal. It gateway terminal into an intermodal network is also presented in detail. The handling – transport –storage system, governed by the 20 – 80 regulation, is perfectly associated with the intermodal transportation idea.

» Keywords: transhipment, intermodal terminal, handling, transportation


  • Miroslav MÜLLER, Petr HRABĚ, Milan BROˇEK, Rostislav CHOTĚBORSKŻ

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INFLUENCE OF LAPPED LENGTH ON ADHESIVE BOND STRENGTH

» Abstract. The adhesive bonding technology is one of many bonding material methods. It is influenced by a number of factors, which affect the adhesive bond strength. Experiments focused on lapped length of adhesive bonds are essential because of the construction parameters and the economic costs. The optimum lapped length was searched from the length values from 5 to 50 mm. If we choose smaller lapped length than the optimum, the adhesive bond will be destroyed. On the other hand increasing the lapped length over the optimum value will cause a distortion in a basic material when loading and the weight of the adhesive bonding complex will rise up. The tests were carried out according to ISO CSN EN 1465 on two materials – steel and duralumin by means of two epoxy adhesives Bison epoxy metal and Alteco 3 - Ton epoxy adhesive 30 min.

» Keywords: Adhesive bonding technology, epoxy adhesives, lapped length, loading force, strength


  • Daniel MUNTEANU, Camelia OLTEANU

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LEAN MANUFACTURING – A SUCCESS KEY INSIDE OF A INDUSTRIAL COMPANY

» Abstract. A Lean Management System is based on cycles of organizational learning in all areas of the company. Its premise is that the most valuable asset in a lean and profitable manufacturing company isn’t the expensive equipment; it is not machines that produce things. Productivity is an effect of human beings working together. Machines are merely an extension of their collective imagination and energy. One of the most used methods for a continuous business improvement is Lean Manufacturing. Lean Manufacturing could be considered an organization management philosophy focusing on reduction of seven wastes to improve overall customer value. These wastes appear on: transportation, inventory, motion, waiting time, over-production, processing itself and defective product. The present article intend to make a briefly presentation of Lean Manufacturing and the main terms that are used in this area, such us: muda, kaizen, kan-ban or poka-yoke, and also to punctuate the key lean manufacturing principles. The paper contains also, an example of a lean implementation program and operational benefits of lean. The study leads to the idea that being directed for performance, lean is the way for the continuous growth of a business.

» Keywords: lean manufacturing, kanban, poka-yoke, waste


  • Mircea NEAGOE, Dorin DIACONESCU, Lucia PASCALE, Radu SĂULESCU

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ON THE EFFICIENCY OF A CYCLOIDAL PLANETARY REDUCER WITH A MODIFIED STRUCTURE

» Abstract. The paper deals with a new variant of a cycloidal reducer with modified structure, proposed by the authors, able to accomplish high transmission ratio and high efficiency. Based on a reducer physical prototype and using a modern high-tech stand, experimental researches on the efficiency in several relevant functioning cases were performed. The obtained experimental results comply with the theoretical model, and some performance features of the reducer prototype are thus derived.

» Keywords: cycloidal planetary reducer, internal efficiency, transmission ratio, experimental testing


  • Ionel NOVAC

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METHODOLOGY AND PROCEDURES FOR APPLYING THE FORWARD-LOOKING GRAPHICAL-ANALYTICAL MODEL DEVELOPED TO FORECAST THE TECHNICAL-ECONOMIC ENVIRONMENT IN MANUFACTURING HEAT-INSULATION CARPENTRY

» Abstract. The paper presents the methodology and procedures used to apply a forward-looking mathematical model developed to forecast the technical-economic environment in manufacturing heat-insulation carpentry. The methodology follows thirteen steps, each step including the procedure for calculating different parameters. The conclusions regarding the model viability are presented at the end of the paper. The conclusion shows that the model was submitted to a two-year test in a factory manufacturing heat-insulation carpentry, being proved its viability.

» Keywords: mathematical model, technical-economic environment


  • Cristina Ileana PASCU

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STUDY ABOUT COPPER INFILTRATION AT MANUFACTURING OF HARD MATERIALS COMPOSITE

» Abstract. This paper presents a study about the porosity after sintering and the final weight percent of copper after infiltration into the parts produced by Powder Metallurgy. The pieces are based on tungsten powder, 78%W - 20% Cu-2%Ni. For this research two kind of tungsten powders with different grain-size distributions have been used. After the homogenisation of mixture 98%W-2%Ni the paraffin content was varied. Thus, were obtained six different mixtures, with 1%, 2% and 3% paraffin contents. The homogeneous mixture W-Ni was pressed with 400 MPa compaction pressure. After sintering the porosity of tungsten skeleton determination was made with the method of the surface integration. After copper liquid infiltration the copper weight percent content for each final piece has been determined. Also, the final mechanical and physical properties of the composites based on tungsten powder have been specified. The microstructure characteristics and manner of copper infiltration into porous tungsten skeleton have been presented, too.

» Keywords: porosity, copper infiltration, tungsten, microstructure


  • Carmen POPA, Ivona PETRE

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MATHEMATICAL METHODS TO DETERMINATE THE UNFOLDING OF THE CYLINDERS

» Abstract. This paper establishes the intersection curves between cylinders, by using the Mathematic 5.1. program. This thing can be obtained by introducing the curves equations, which are inferred, in Mathematic 5.1 program. This paper takes into discussion two cylinders.

» Keywords: unfolding, intersection curve, cylinder, projection vertical


  • Horia Liviu POPA, Marian Liviu MOCAN, Liana Rodica PATER

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STRUCTURES AND PROGRAMMES FOR THE CLUSTERS COMPETITIVENESS INCREASE IN ROMANIA

» Abstract. In the last years the European Union 25 and the new country members Romania and Bulgaria have had negative growing competitiveness gaps comparatively to the USA, North America and Asia-Pacific Zone. The classical political and managerial approaches, the insufficient total radical innovation (integrated in technology, management and policies, competitiveness culture) contributed to the relative decrease of the Romania’s and enlarged EU’s competitiveness. Romania and moreover the European Union 27 cannot accept in the XXIst century the persistence of the competitiveness gaps (–ΔK), which are unfavourable to them. We analyse and characterize the integrated ways for the competitiveness development of the Romanian clusters and enterprises. We propose new structures and programmes for the sustainable competitiveness increase of the Romanian economy.

» Keywords: competitiveness gaps, integrated ways, sustainable competitiveness increase


  • Cătălin POPESCU

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KEY MODELS FOR VIRTUAL ENTERPRISE. BASIC ASPECTS FOR TODAY'S FIRMS’ MANAGEMENT SYSTEMS

» Abstract. On one hand, a Virtual Enterprise is a simulated business that is set up and run by people to prepare them for working in a real business environment. In respect with this, a Virtual Enterprise offers to the people the opportunity to experience in a simulated business environment all facets of being an employee in a firm. On the other hand there is a new approach that considers a Virtual Enterprise represents a new structure that could help in a challenging and a very dynamic environment. Therefore, knowing models concern virtual enterprise could help in understanding how today a company could be ran by using different approaches of management systems.

» Keywords: virtual enterprise, models, business environment, management systems


  • Radu Cristian POPESCU, Gheorghe OBACIU

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APPLICABILITY OF STANDARDS ISO 9001/2000, QS-9000 AND TS16949 IN MAINTENANCE

» Abstract. The article treats the 3 different standards and client requests (ISO 9001/2000; QS-9000; and TS16949), explaining shortly how they got “birth”, why it was necessary to have a global valid standard of certification in quality management, and how this standard is applicable in the maintenance activity, being a step for implementation of Total Productive Maintenance.

» Keywords: standard, process-orientation, uptime, OEE


  • Carmen TACHE, Ştefania IORDACHE

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THE ANALYZE OF THE TEMPERATURE FIELD AT THE TOOL NOSE, DURING THE CUTTING PROCESS

» Abstract. During the cutting process, between tool and work piece appear friction couple which can be considered a system with interconditioned elements. Using an global model regarding the calculus of the heat fluxes and the finite element analysis method (CosmosWorks programmer) it is determined the temperature field at the nose of cutting tool.

» Keywords: cutting tool, temperature, tool nose, finite elements analyze, heat flux


  • Ion TUREAC

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CONSIDERATIONS UPON THE DESIGN OF THE MACHINE-TOOLS IN ACCORDANCE WITH THEIR DUTY CYCLE

» Abstract. The product design, their fabrication and consumption in compliance with the principles of the market economy have resulted in the current economic development, which may be characterized through reaching a satisfactory level of the well-being and through the utmost deterioration of the environment health. In order to cast away the possibilities of aggravation of the disequilibrium between the economic rise and the environment quality, there is necessary to reconsider the criteria on whose basis the products have been made and consumed so far and to pass to a new manner of approach. In this paper there are presented the deficiencies of the current manner of conceiving and designing an important group of products – the one of the machine-tools. According to the paper, there is necessary, in the prospect of the rise in the demand of consumption goods and production means, for these products to be designed so as their impact upon the environment should be eliminated or reduced to the lowest level. The paper enhances the possibility of our possessing, in the future, machine-tools that should have a less cumbersome influence upon the deterioration of the environment, through taking into consideration their entire duty cycle during the design phase. Under these circumstances, approaching a management of the environment turns into reality in complete compliance with the principles of durable development.

» Keywords: duty cycle, machine-tools, sustainable development


  • Mihaela VARTOLOMEI, Diana BĂRGLĂZAN

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ASPECTS OF THE CONVERGENCE PROCESS INSIDE THE EU – ENDOGENOUS GROWTH PERSPECTIVE

» Abstract. In this paper the authors want to make a brief analysis regarding the potential effect of the EU accession on the development of old and new member states, in terms of economic aggregate (price, wages), the production relocation and the division of work in the EU, the relocation of jobs in the member states, but also in terms of nominal convergence into the EU. In this way, a small open economy version of the two-sector endogenous growth model is designed and the concept of human capital is introduced into the standard Lucas−Uzawa model of endogenous growth, with knowledge diffusion. The model is calibrated for the EU periphery countries first, than in the new member states and the old member states to stylized facts of the economic development during the accession process and the convergence process inside the European Union. The initial conditions and the parameters of the accession generate different accession patterns and also rather different speeds of economic, social, political, judicial and commercial convergence to the EU average.

» Keywords: real convergence, nominal convergence, endogenous growth


  • Sorin VARTOLOMEI, Mihai JĂDĂNEANŢ

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APPLICATIONS OF ADVANCED MATERIALS IN ROMANIAN MILITARY TECHNOLOGY FOR REDUCING THE ARMORED FIGHTING VEHICLES' VIBRATIONS

» Abstract. It seems that the military intervention mode is in a changing process with the new millennium. The creator process to obtain materials very advanced, efficient, resistant, not be battered, not be heavy, can be easy processed and to combine more specific featuring. The tanks and armored combat vehicles, as every land automobile, don’t have surplus of suspension and own shock absorber (damper), so the shock and vibration effects are more aggressive for the attendance persons in this type of motorcar that other motorcar. In the tank soldier activity, the main problem is to be insured some specific conditions in order to eliminate or reduce the vibrations and their effects; these are much needed aspects for accomplishing the combat missions. The using of composite materials in order to damp the shocks and vibrations, in armored combat vehicles, is very useful for a long distant movement or while the fights. Concomitantly, all these are further argument for the designer of combat technique to ameliorate the life and fight conditions on armored combat vehicles. The impressive technological progress using the new discovery and combination in advanced materials applied in military technique has lead to a new perception of the military interventions.

» Keywords: advanced materials, armored combat vehicles, vibrations’ effects


 

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