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Recent 34

Vol. 13 (2012), No. 1 (34), March 2012

 

This issue of the RECENT® journal was edited and multiplied with support of:

  • Transilvania University of Brasov, Romania

  • Romanian Association for Nonconventional Technologies


CONTENTS


  • Smain AIB, Abellatif AIB, Rachid CHAID, Ion VERZEA

Diagnosis of Geometrical Defects and Rebuilt Method of Machine-Tools Accuracy

» Abstract

Today companies are, more than ever, faced to steady growing competition and must produce higher quality at lower costs. However in industry machinery are used and suffer of accuracy, dysfunction, loss of performance, etc. These affect heavily the costs of production and hence increase sales prices. In this work, it has been proposed to the maintenance services, a tool which helps to diagnose the geometrical defects of a machine tool and a scrapping method to recover its original geometry, hence leading to working accuracy and good performance. Once the execution of all the necessary steps to rebuilt geometry, done. The reshaped machine will recover the optimum machining delays, operating costs, and its minimum waste production. This study was realized between the mechanical engineering laboratory at Mentouri University and the Algerian machine-tools and equipment’s ALEMO, subsidiary company of the National Enterprise for Machine-tools production located in Oued Hamimime, Khroub, Constantine, Algeria.

» Keywords

loss of performance, accuracy, geometrical defects, maintenance, geometrical rebuilt, diagnosis help tool

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  • Romeo CIOARĂ

Spherical Hypocycloids and a Technical Application: Spherical Hypocycloidal Automatic Machines for Cold Forming

» Abstract

Plane hypocycloidal automatic machines, which form an entire family, are a Romanian original concept developed at Transilvania University of Brasov. Recent researches have enhanced the concept development towards a very diverse new sub-group, the spatial spherical hypocycloidal automata. In the main kinematic chain of these machines, a planetary gear with conical wheels is included, generating spatial spherical (hypo)cycloidal trajectories, as transformation mechanism of the rotation motion of the main shaft, in rectilinear-alternative translation movements, with periodical and temporary self-return of the slide-blocks. The paper herein sets out to submit the theoretical basis for determining the kinematic parameters of these machines, namely the space, speed and acceleration expressions of the slide-blocks. To this purpose, one must know the equation of the spatial spherical (hypo)cycloid. The class of the equatorial spherical hypocycloidal automatic machines is pre-eminently targeted, deemed the most adequate for practical applications.

» Keywords

spatial spherical cycloids, automatic machines for cold forming, kinematic parameters

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  • Ioan CIOBANU, Ciprian SZABO, Aurel CRISAN, Tibor BEDŐ, Sorin Ion MUNTEANU

Experimental Research Regarding Wood Insulated Exothermic Feeders

» Abstract

The paper presents research results regarding the possibility to increase the feeder efficiency by applying sand cores with wooden panel insertions onto the feeders. The wooden panels are inserted in the side walls and the upper part of the core. There were compared the functioning of wood insulated feeders with that of non-insulated feeders and of feeders insulated with exothermic material of Al + Fe2O3 + SiO2. The results showed that the use of exothermic feeders insulated with punchholed wooden panels led to an increased index of liquid alloy use of approx. 46% compared to simple feeders..

» Keywords

cast, casting, feeder, exothermic feeder, shrinkage

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  • Konstantin D. DIMITROV

Fuzzy-Neural Modules for Evaluation of Technological and Reliability Characteristics in Industrial Products

» Abstract

The present paper describes the development of a modular fuzzy-neural (FN) system, designated for practical application of fuzzy sets for determination of fuzzy membership functions. A NN-structure, possessing a back propagation learning algorithm, which is developed under monotonic function constraints, is applied for generation of fuzzy membership functions. The so-developed FN structures and the generated fuzzy membership functions are then applied for evaluation of technological and reliability characteristics, but also for revealing the relationships, existing between the properties of some particular industrial products (e.g., XPS thermal insulation boards, applied in construction industry).

» Keywords

fuzzy-neural system, fuzzy membership functions, technological and reliability characteristics, relationships in industrial products properties

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  • Florina-Cristina FILIP, Vladimir MĂRĂSCU KLEIN

Theoretical Concepts on Supplier Agreement Management

» Abstract

Within the scope of the process improvement program it is intended to select suppliers according to defined criteria, to establish agreements with the supplier, to control the progress and to review and accept the results/deliverables. This paper comprises the process description of the topic “supplier agreement management” and explains target and handling of the process. The process description addresses the project leaders, who have to manage the acquisition of products and/or services from suppliers. This process covers explicitly the supply of components/services by the projects customer, does not address arrangements in which the supplier is integrated directly into the project team, does not cover explicitly the acquisition of development tools and test environment and is placed under an obligation for all types of projects.

» Keywords

supplier, process, agreement, requirement

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  • Aurel FRATU, Mariana FRATU

Robot Control for Avoid Self-Collisions

» Abstract

The present paper generally relates to robots, more specifically to robots acting autonomously and requiring a safety method to avoid collisions with other objects as well as collision between one moveable segments of the robot. The authors have tested an avoid collisions method on complex simulation scenarios involving a virtual robot and have estimated collision-free actions. The virtual robot is able to react to avoid the obstacles while executing the robotic tasks. This was shown experimentally with a virtual system. This kind of robot’s behaviour simulation will be necessary in real applications, where interactions between robot and her environment are vital.

» Keywords

self-collision prevention method, collision avoidance control, dynamic simulation protocol

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  • Mariana FRATU, Aurel FRATU

Collision Avoidance Control Using Null Space Criteria

» Abstract

A new strategy to on-line collision-avoidance of the redundant robots with obstacles is presented. The strategy allows the use of redundant degrees of freedom such that a manipulator can avoid obstacles while tracking the desired end-effectors trajectory. The effectiveness of the proposed strategy based on null space criteria is discussed by theoretical considerations. The strategy is based on the redundant inverse kinematics and leads to a favourable ability of redundant robots to avoid the collisions with obstacles. This strategy has the advantage that the configuration of the manipulator can be influenced by further requirements such as joint limits and so the self-collision is avoided.

» Keywords

collision avoidance method, obstacles avoid task, self-collision

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  • Veska GANCHEVA, Adelina ALEKSIEVA-PETROVA, Stilyana YANEVA

Ontology for Semantic Data Description in Scientific Domain

» Abstract

The scientific data obtained from different experiments are heterogeneous and stored in different file formats. Discovering, integrating and distributing of such data are challenges nowadays. OWL ontology for semantic data description is proposed in this paper. The ontology structure including classes and property hierarchy and relationship of the general ontology is explained. An RDF instance of the input XML file on the basis of the ontology is obtained. This should allow efficient description, storing, discovering and interpreting of the scientific data through the semantic web. A software framework for transforming raw data obtained from various scientific experiments into RDF instances on the basis of XML data description and the proposed ontology is developed. The framework is implemented as web service and consists of several key elements: XML scientific data description; ontology describing in detail the significance of semantics and XML data; the correspondence between the XML schema and OWL ontology is determined in accordance а mapping document. A number of experiments using specific scientific dataset in the cases of physical field data as radiation and spectral measurements obtained from experimental instruments are conducted to illustrate the usage of the proposed ontology and the software framework.

» Keywords

ontology, OWL, RDF, scientific data, semantic Web, XML

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  • Aurel LUNGULEASA

Quality and Marketability Index of Wooden Briquettes

» Abstract

Briquettes from wood are one of the easiest solutions to obtain renewable energy with low costs. European standards shows a lot of physical, mechanical and chemical properties of briquettes, but there is not a singular characteristic to quantify all their properties and consequently to determine the quality. Therefore this paper aims to unify all these properties into one, in order to find such an individual quality of briquettes. Normally, all products have a price that influences the acquisition cost of these briquettes in correlation with the quality. In this way the paper wants to identify only products that have the best quality-price ratio and therefore the best-selling power. Marketability index can be found on these above bases.

» Keywords

renewable fuel, briquette, integrated property, marketability index

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  • Alexandru-Ioan MILOŞAN, Xueyu WANG

Foreign Policy Analysis between China, Romania and the EU

» Abstract

The paper presents an analysis on the foreign policy between China, Romania and the EU. That Foreign Policy Analysis (FPA) enjoyed central place in the early study of international relations (IR) can be considered as the starting point for understanding the evolution of this major sub-field. Examining the history, conceptual breadth, and recent trends in the study of foreign policy analysis, it is clear that this subfield provides what may be the best conceptual connection to the empirical ground upon which all international relations (IR) theory is based. Foreign policy analysis is characterized by an actor-specific focus, based upon the argument that all that occurs between nations and across nations is grounded in human decision makers acting singly or in groups. What is the foreign policy of China towards Romania, what about the foreign policies of Romania towards China and does the EU have anything to say about this?

» Keywords

foreign policy analysis (FPA), international relation (IR), relationship between China, Romania and the EU, sovereignty, strategic position, economical relation

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  • Ioan MILOŞAN

The Kinetics Transformation of a Low Alloy Cast Iron

» Abstract

The Austempered Ductile Iron (ADI) obtained by heat treating and isothermal hardening, is the material, which combines a lot of the superior attributes of classical Ductile Irons or forged irons, being in a serious competition with the iron used by the moment in the automotive industry. The paper presents an application for calculating the kinetics and thermodynamics parameters in the case of a phase transformation in solid state in A.D.I. S.G. grade. The studied cast iron has the following chemical composition (% in weight): 3.73% C; 2.77% Si; 0.44% Mn; 0.057% P; 0.009% S; 0.047% Mg; 0.23% Cu; 0.15% Ni; 0.10% Cr. This cast iron was made in an induction furnace. The isothermal bainitic transformation in a Ni-Cu S.G. cast iron was studied in the temperature range of 375-400 oC and with maintaining time between 1 to 60 minutes. It is pointed out the influence of some factors (the temperature and the maintained time at the isothermal level) on the phase transformation and properties in the studied cast iron. By the help of Johnson-Mehl-Avrami equation it was described the kinetics of austenitization of S.G. Cast Iron and it was determined the reaction exponent “n” and the bainitic reaction rate "k".

» Keywords

cast iron, heat treatment, phase transformation, kinetics transformation

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  • Lavinia Nicoleta NEAGOE

Method for Quality Cost Production System Implementation

» Abstract

Today's competitive environment requires industrial companies to find solutions to survive and be profitable. Approaches such as Lean Six Sigma and World Class Manufacturing provide a set of techniques and tools which are technical solutions, but also highlight the role of organizational culture. These systems, developed based on Toyota Production System (TPS), have tried to replicate the success of Toyota, but frequent implementation failures registered leads to the suspicion that the TPS's DNA is not fully understood. Based on the authors' ten years’ experience on production systems implementation, the success of implementation consists in management commitment, a clear plan and sustainable practical application. This paper presents a global method, which describes the necessary steps for successful implementation of a production system for identifying, monitoring and control of non-quality costs in order to reduce them through daily activities and optimization projects.

» Keywords

TPS, production system, implementation, method, quality cost, optimization

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  • Rodica PĂUNESCU

Automated Feature Recognition and Extraction from CAD Models

» Abstract

Automated feature recognition is considered a critical component for integration CAD and CAPP. The goal of these systems is to recognize and extract features of a part stored in the CAD files and to drive CAPP system which generates process plan. Most current automated feature recognition systems have difficulties in processing of the parts having complex and interacting features. This paper presents a review of strengths and weaknesses of these automated methodologies.

» Keywords

manufacturing feature, recognition, automated methods, CAD/CAM/CAE/PDM applications

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  • Tudor PĂUNESCU

Magnetic Workholdings: Recent Advances and Trends

» Abstract

In the last decade new innovations like permanent-electro magnets and permanent magnets have greatly increased the applicability of the magnetic fixtures. An attempt at summarizing and analyzing the recent development in the field of the magnetic work holdings and especially of the electro-permanent magnetic fixtures is made.

» Keywords

magnetic work holding, permanent-electro magnet, magnetic fixture analysis

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  • Ioana PETRE

Studies on the Forces Developed in a Rehabilitation Equipment Slider

» Abstract

The paper presents the experiments performed to determine the forces developed by a drive system of rehabilitation equipment. As actuator is used a pneumatic muscle, which works on a spring principle - increases its diameter and decreases its length under the action of compressed air. Determination of the available force developed by the pneumatic muscle is performed using a force transducer attached to the equipment slider and connected to the computer. The results of the experiments made, presents the drive system forces evolution developed for a load cycle and for a load/unload cycle with pressures between 1 and 6 bar.

» Keywords

pneumatic muscle, rehabilitation equipment, force transducer

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