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Recent 39

Vol. 14 (2013), No. 3 (39), November 2013

 

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CONTENTS



  • Virgil Nicolae CÂNDEA

Loading Thermal Cycles Produced by Welding Steel Molds and X 30 WCrV9 3 and 55 NiCrMoV 6

» Abstract

The paper presents the influence of thermal cycles upon the thermally influenced area by the loading by welding procedures, 111, 136, 141 EN 287-1/2004 of the materials X 30 WCrV9 3 and 55 NiCrMoV 6 from which hot working moulds are made. The thermal cycles undergone by the test specimens made of the studied materials and the microstructure of the steel X 30 WCrV9 3 and 55 NiCrMoV 6 obtained in different thermal cycles are presented. In the case of loading by welding of the moulds made of steel X 30 WCrV9 3 and 55 NiCrMoV 6, high productivity welding procedures are not advisable, but manual electrical welding and WIG welding.

» Keywords

materials, welding, mechanical tests

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  • Ivan DIMITROV, Petko YANGYOZOV

Method of the Sub-Processes Improvement in the Organization

» Abstract

Present article presents a set of methods, through which the existing inefficient sub-processes or activities within the business process frames could be reorganized. This way, it can be done improvement as the partial efficiency of each process unit, as well as the business process as a whole. A classification and a scheme which reflecting the influence of the presented processes optimization methods towards the four most often used dimensions of the processes through the aspects of optimization of the business processes are presented. Each method’s essence of functioning and application is explained, as well as their graphic image. The advantages and the shortages of the application of each one of them are derived.

» Keywords

business process, sub-process, optimization, improvement tools, process dimensions

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  • Daniela GOTSEVA

Stateful Knowledge Session Implementation with Rete Algorithm

» Abstract

This paper discusses some concepts related to the Rete Algorithm, which consist of two parts: compilation and runtime execution. After a brief explanation of Rete Algorithm and its combination with the latest technology the stateful knowledge session is discussed and the cross product is presented.

» Keywords

Rete algorithm, artificial intelligence

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  • Ioan MILOŞAN

Phase Transformation in Austempered Ductile Irons

» Abstract

Austempered Ductile Iron (A.D.I.) with a bainitic matrix, obtained by heat treatment and isothermal hardening is the material which combines a lot of superior attributes of the classical cast iron or forged iron, being in a serious competition with the iron used by the moment in the automotive industry. Austempered ductile irons usually contain a large quantity of retained austenite that can help to optimise their mechanical properties. Many of the properties of austempered ductile iron depend on the austenite which is retained following the bainite reaction. The paper presents a study that determines the influence of the heat treatment parameters over the the volume fraction of the retained Austenite (Vγr) and of the Carbon content (Cγ) of the retained austenite. The studied cast iron has the following chemical composition (% in weight): 3.70% C; 2.46% Si; 0.56 % Mn; 0.038% P; 0.009%S; 0.062%Mg; 0.21% Mo 0.12% Ni, 0.17% Cu. This cast iron was made in an induction furnace. Nodular changes were obtained with the "In mold" method, with the help of prealloy FeSiCuMg with 10-16% Mg, added into the reaction chamber in a proportion of 1.1% of the treated cast iron.

» Keywords

ductile iron, heat treatment, phase transformation, retained austenite, bainite

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  • Vasile PRISACARIU

The UAVs in the Theatre of Operations and the Modern Airspace System

» Abstract

The field of UAVs is continuously evolving both in terms of constructive solutions and tasks that they can accomplish. The success recorded by unmanned aircraft in military operations has generated increasing interest in their use among the armed forces. Technological advances offer leaders information beyond real time visual range. The advances in optoelectronics and nanotechnologies as well as the perspective of using smart materials enable the design of UAV projects as bold as possible. The current paper aims at presenting an image of the unmanned air systems in terms of capabilities and advantages of operating in the present conditions of the modern airspace, and the types of sensors and existing equipment on board.

» Keywords

unmanned aircraft, security, versatility, sensors, sense and avoid

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  • Artem SAZONOV, Lubomir DIMITROV, Valerii KYRYLOVYCH

Quaternion Accuracy Model of Industrial Robots

» Abstract

The article describes existing methods and approaches to industrial robots accuracy simulation based on the matrix methods at multiply industrial robots’ motions. The main problems and disadvantages of using these existing approaches based on the analysis of informational sources also shown. Quaternion-based method of industrial robot kinematics and accuracy simulation proposed to decrease these disadvantages for stochastic simulation at multiply motion of industrial robots’ grippers. Forward kinematics task and Forward accuracy task solving using the proposed quaternion-based method described also. The Industrial robots’ quaternion accuracy model proposed to use as a basis of accuracy simulation for examine their working space.

» Keywords

industrial robots, accuracy, quaternions, industrial robots’ accuracy model

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  • Vasile ŞANDRU, Marius RĂDULESCU

Requirements for Ground-Based Air Defense Integrated Systems

» Abstract

The Air Defense (A.D.) represents a really support for any military operations. Between the A.D. assets, Surface-to-Air Missiles are the most important features in endowment, allowing dealing the rapid evolution of enemy’s air assets. The paperwork presents the basic requirements focused on integrated systems - missiles and cannons. Important distinctions between the missile’s and system’s requirements are made. The conclusions are useful for all the military managers who have the responsibilities concerning the maintenance and acquisition plans regarding this kind of equipment.

» Keywords

missile, air defense, range, efficacy, upgrade

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  • M. SUMAN, M. VENU GOPAL RAO

Artificial Neural Network Based Short-Term Hydrothermal Scheduling

» Abstract

A worldwide trend in the development of power systems is to build interconnections with the goal to achieve economic benefits. Interconnections of power systems may offer significant technical, economic and environmental advantages. A modern power system consists of a large number of Thermal and Hydal Power plants connected at various load centres through a transmission network. An important objective in the operation of such a power system is to generate and transmit power to meet the system load demand at minimum fuel cost by an optimal mix of various types of plant. In this paper Kirchmayer’s method is used for hydrothermal scheduling which is a conventional method and slow. In order to overcome the disadvantage in the Kirchmayer’s method, Back Propagation Neural Network (BPNN) is proposed for scheduling of Hydro-Thermal system. The result shows the effectiveness of the proposed method compared to the conventional in terms of speed and accuracy.

» Keywords

hydrothermal scheduling, economics of power generation, Kirchmayer’s method, artificial neural networks

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  • Galina TODOROVA, Valentin DIKOV

Selection of the Proper Layout of Manufacturing Lines

» Abstract

A developed methodology for automated implementation of an experiment using the coordinate-grid method is applied. The presented experimental displacements obtained by means of a specialty designed program system are compared with those obtained by FEM analyses. The uncertainty of the displacements is evaluated too.

» Keywords

automation of the coordinate-grid method, experimental determination of displacements, displacement uncertainty

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