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Recent 32

Vol. 12 (2011), No. 2 (32), July 2011

 

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

  • Transilvania University of Brasov, Romania

  • Romanian Association for Nonconventional Technologies

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


CONTENTS


  • Mihai ALEONTE, Radu COSGAREA, Corneliu COFARU, Kai W. BECK, Amin VELJI, Ulrich SPICHER

Experimental Investigations of Alcohol Blends on Combustion and Emissions in a Two Stroke SI Engine

» Abstract

Internal combustion engines play a major role in transportation, due to the future emissions reduction legislation; researches are done in order to improve the combustion process behaviour and lowering the exhaust emissions. Two-stroke engines have a very good power-weight ratio, reliable, and they have a simple mechanical structure. The aim of this paper was to investigate the combustion process and the resulting exhaust emissions by using the air – assisted direct injection (DI) fuelling system and alcohol blends as fuels. For this experimental investigation the air–assisted DI was combined with a flame ionization detector (FID) and a CO, CO2 and NOx analyzer in order to measure the resulting exhaust emissions of the combustion process.

» Keywords

engine, combustion, gasoline, alcohols, exhaust emissions

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  • Romeo CIOARĂ, Ovidiu SÎRBU

Strain and Motion Model of a Self-Adjusting Speed Bicycle Transmission

» Abstract

The endowment of bicycles with a simple and innovative self-adjusting speed transmission, easily customizable in order to meet the requirements and performance of various users would be particularly beneficial from the bicycle rider’s viewpoint, who would thus be relieved from performing periodical adjustments of bicycle motion to frequently varying road and environment conditions. Most bicycle users are undemanding in relation to special endowments of the bicycle, as being relatively idle, uninterested in or even bothered by frequent manual changes of the transmission ratio. The paper presents a strain and motion model of a self-adjusting speed transmission, with a V-belt and a cone-disk variator mounted only on the pedal spindle. Operation and self-adjusting of the transmission follow clearly and explicitly.

» Keywords

belt transmission, self-adjusting, strain-model, bicycle

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  • Ioan DAN

Research on the Influence of Tilted and Curved Ribbing on the Stiffness of PAI 25 Presses

» Abstract

An important component of presses, frames frequently represent 50 ÷ 60% of their mass. Building presses of adequate rigidity is an important objective, with significant consequences on the quality of the respective machines and on their energy consumption during operation. Most often rigidity is improved by increasing the volume of utilized material. The paper presents a number of constructive solutions for increasing the stiffness of press C-frames by ribbing of the lateral walls. Only solutions involving straight cross ribs and curved ribs are addressed. Previous studies on straight cross ribbed frames have allowed the identification of a set of values of rib geometrical characteristics, which has almost systematically yielded the best results. This set of values is used in all models discussed in the paper.

» Keywords

optimization, mechanical crank press, FEA, ribbing, stress

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  • Konstantin D. DIMITROV

Neuro-Fuzzy System for Enhanced Fault Diagnosis in Industrial Facility

» Abstract

The present paper describes the development of a modular neuro-fuzzy system, designated for enhanced and flexible fault diagnosis. Some specific neural algorithms for identification, recognition, evaluation and classification of the process parametric values are created and applied in the systems structure. The so-developed neuro-fuzzy system is then applied for fault diagnosis in an industrial zinc galvanizing facility, i.e., under real operational conditions.

» Keywords

process fault diagnosis, neuro-fuzzy system, neural networks, fuzzy models, pattern recognition

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  • Valentin DITU

Comparative Study of Using Cutting Fluids at Turning and Drilling Using the Cutting Electric Thermocurrent

» Abstract

The paper’s purpose is to appreciate the efficiency of using cutting fluids at turning and drilling using a new method, the measurement of the electric thermocurrent at cutting instead of the measurement of the cutting forces. The obtained experimental dates show the accuracy and the simplicity of the method. The comparison between using cutting fluids at turning and using cutting fluids at drilling is easy to accomplish. Also the using of the cutting electric thermocurrent in the appreciation of the efficiency of using cutting fluids represents an instrument easy to apply when cutting fluids from several companies are being bought.

» Keywords

cutting, electric thermocurrent, turning, drilling

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  • Florina-Cristina FILIP, Hassan SHIRVANI

Method and Analyze of the Production Capacity Calculation

» Abstract

The capacity analysis shows the shortages for enabling a request for necessary investments. This paper follows to present the creation of a capacity analysis for business units, product lines and plants of company at the work center level, and the handling and the content of capacity statements made by the customers (sample, volume production and capacity statements in enquiry process). The target group for this paper is all employees who create or approve capacity analysis and request investments for production machines. This may include employees engaged in production scheduling, facility planning, investment planning, budgeting and controlling.

» Keywords

capacity, cost, production, budgeting, cycle time

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  • Aurel FRATU

Collision Prevention Method for a Dynamic Group of Cooperative Robots Who Communicate Wirelessly

» Abstract

This paper presents the collision prevention method for the cooperative robots who communicate wirelessly. The basic idea is in essence a mutual exclusion on reserved zones in the work space. When a robot reserves a zone, her gripper can move safely inside the zone. When a robot’ gripper wants to move along a given corridor it must reserve the zone that surrounds this corridor. Once the gripper reaches the end of the corridor, it releases the zone except for the area that the robot occupies.

» Keywords

collision prevention, cooperative robots, wireless ad hoc networks

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  • Mariana FRATU, Aurel FRATU

Collision Prevention Protocol for a Dynamic Group of Asynchronous Cooperative Robots

» Abstract

The protocol is based on a fully distributed path reservation system. It assumes an ad hoc network formed by the mobile grippers of the robots, and takes advantage of the wireless communication. The protocol requires initial complete knowledge of the composition of the robots group. A performance analysis of the protocol provides insights for a correct dimensioning of system parameters in order to maximize the average effective speed of the robots’ grippers.

» Keywords

collision prevention protocol, autonomous cooperative robots’ grippers, distributed algorithms

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  • Aurel LUNGULEASA

The Temperature Effect on Wood Shrinkage

» Abstract

The paper presents some aspects of the temperature influence on the wood shrinkage in general and especially on the beech specie. After analyzing the existing documentations it goes to make own experiments on this problem and are drawn the conclusions. Emphasis is placed on the differences between radial and tangential shrinkage but here is found the relationship for determining the volume shrinkage related to the radial and tangential ones.

» Keywords

wood shrinkage, the temperature effect, wood drying

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  • Cosmina PÖLLNER

Creative Approaches Concerning Mechanical Vulcanizing Presses

» Abstract

Any technical solution newly appeared can be useful to development and evolution of society and is strongly linked to research, discovery, identification and implementation of some techniques and technical creation methods. Formulation of creative technical issues, meaning enunciation of problems, determines largely results. In some cases it takes successive reformulations until is identified correctly the essence of the problems that are intended to be studied, problems which must be found new solutions, originals, effectively. The present paper presents creative approaches which have been useful for designing mechanical vulcanizing presses with a single screw, mechanical vulcanizing presses with two screws and mechanical vulcanizing presses with two screws and knee mechanism.

» Keywords

creative approaches, inventions, mechanical vulcanizing presses, technical creative techniques

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  • Răzvan RĂCEU

Other Types of Equatorial Spherical Hypocycloid Automatic Machine

» Abstract

Equatorial spherical hypocycloid automatic machine, under equatorial and over equatorial was already identified as possible. Researches conducted so far by the author have focused exclusively on the equatorial spherical hypocycloid automatic machines (AHSe), particularly those with a 2:1 ratio between the numbers of teeth of the fixed plane central gear and the satellite gear. This research has, as results, two patent applications registered at OSIM. AHSe with one satellite and two or more trajectory generating points placed “externally” are similar as operation and construction of those with trajectory generating points placed “inside”. Location “on the outside” of the generating points may be favourable in terms of access to them and certainly determines an increase of distance between two neighbours slide blocks’ in conditions of the same angular space between them.

» Keywords

equatorial spherical hypocycloid automatic machine, spherical hypocycloid, invention

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  • Kalin RADLOV, Vesko PANOV

Seismic Safety of Bridge Crane Steel Structures Operating in NPP

» Abstract

The seismic stability assessment of systems and equipment operating in Nuclear Power Plants (NPP) is a very important preventive precaution for ensuring their emergency safety. The actuality of this case study arises extremely after Fukushima NPP disaster, caused by the earthquake on 11 March 2011. Bridge cranes are a significant and integral part of the technological equipment, which affects the modern NPPs’ safety. The main aim of the present study is to propose an analytic-simulation approach for analysis of bridge crane steel structures dynamic behaviour during earthquake impact as to evaluate mostly the sliding ability of crane travelling wheels on rail roads. Loads and harmful effects acting on the crane bridge steel structure caused by the sliding phenomenon are defined and analysed.

» Keywords

bridge crane, steel structure, seismic impact, sliding, safety

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