Volume 21, No. 2 (2015)
Articles
KINEMATICS OF MECHANISM WITH ROTATING CAM AND FLAT FACE OSCILLATING FOLLOWER. PART I: ANALYTICAL SOLUTIONS
STELIAN ALACI(1), FLORINA CARMEN CIORNEI(1)
The paper aims to analyze the kinematics of the mechanism with rotating cam and oscillating flat face follower. Compared to the knife edge follower, which has a fixed contact point on the follower, the flat face follower presents a mobile contact point with respect to the follower, with complex kinematics. Additionally, the tangency constraint between cam and follower makes difficult the position analysis. The analysis is made in two manners: the geometrical restraint method and the vector-contours method. Both methods offer the same solution, but the actual expressions differ considerably. There are obtained the position angle, the angular velocity and angular acceleration of the follower and the position, velocity and acceleration of the contact point with respect to the follower.
KINEMATICS OF MECHANISM WITH ROTATING CAM AND FLAT FACE OSCILLATING FOLLOWER. PART II: NUMERICAL AND EXPERIMENTAL METHODS
STELIAN ALACI(1), FLORINA CARMEN CIORNEI(1)
The first part of the work studied the rotating circular cam mechanism with flat face follower using analytical methods. The second part analyses the mechanism from kinematical point of view employing numerical methods and experimental techniques. There is a perfect agreement between numerical and analytical results, but the experimental results are more difficult to evaluate and compare as they are influenced by numerous error sources. The paper presents these inaccuracy sources and the ways to diminish their effects.
CHARACTERIZATION OF RHEOLOGICAL PROPERTIES OF SEMISOLID MATERIALS USED AS THERMAL INTERFACES. PART II: EXPERIMENTAL TESTS
FLORINA-CARMEN CIORNEI(1), STELIAN ALACI(1)
The paper presents the proposed experimental methodologies employed in testing thermal greases. The data obtained from static tests, shearing test and filament stretching tests are used in estimating the parameters required for theoretical modelling of the material. Newtonian, viscoelastic and viscoplastic models were considered in correlating the experimental results to theoretical models necessary in interpreting and planning the material behaviour.
ASPECTS REGARDING THE ELECTROCOAGULATION APPLICATIONS IN THE WATER AND WASTEWATER TREATMENT
AIDA DERMOUCHI(1), MOSSAAB BENCHEIKH-LEHOCINE(1), SIHEM ARRIS(1), VALENTIN NEDEFF(2), NARCIS BARSAN(2)
Electrocoagulation (EC) has been known for over a century. Applications in industry as water and wastewater treatment processes were adapted for the removal of suspended solids, organic compounds, COD (Chemical oxygen demand), BOD (biochemical oxygen demand), metallic and non-metallic pollution. The main advantage in EC technology is the fact that it works without the addition of chemical products. The DC current between metallic electrodes immersed in the effluent is used as an energy source for this technique, which causes their dissolution. The effect of the main parameters, current density, treatment time, initial pH, temperature, electrode materials, conductivity and distance between the electrodes were investigated. According to the conclusion of the works published in recent years, the removal efficiencies of pollutants materials by EC process are very important.
A NEW ALTERNATIVE OF IMPROVING WATER QUALITY CONSUMPTION INDICATORS USING CURRENT STATISTICAL APPROACH SIX SIGMA (6 σ)
ION DURBACĂ(1), ELENA-FLORENTINA RADU(1), ADRIAN-COSTIN DURBACĂ(1)
The concern for quality assurance and improvement of water intended for technological and human consumption is a very topical issue at the state level to any organization, regardless of the activity profile and thus guarantees quality compliance (assurance), performance, competitiveness and organizational profitability. This paper addresses the need to improve water quality indicators of consumption through “Six Sigma”, a statistical method which is based on reducing non-conformities in specified limits and to ensure maximum effectiveness, equivalent to yield 3.4 defects per million opportunities.
GEOMORPHOLOGICAL CHANGES IN BUCHAREST CITY OVER THE LAST 150 YEARS
DIANA GHEORGHE(1), IULIANA ARMAŞ(1)
Bucharest, the capital of Romania, is situated in the Romanian Plain and is being drained by Dambovita and Colentina Rivers. During the last 150 years, the natural landscape has been intensely modified by its inhabitants. The most prominent change has been made in the Dambovita floodplain, where the natural land features have been completely changed. The present paper aims to highlight the major geomorphological changes that Bucharest suffered over the last 150 years. The major human intervention was the improvement of Dambovita channel and the demolition and/or the construction of different buildings during the communist period. Besides the human induced geomorphological changes, there is also soil creeping as a natural geomorphological phenomenon that shapes the landscapes of Bucharest.
DETERMINATION OF SOUND ABSORPTION COEFFICIENT FOR PLATES AND LAYERED COMPOSITE MATERIAL MADE FROM TEXTILE WASTE AND CORK
IULIANA IAŞNICU (STAMATE)(1), OVIDIU VASILE(2), RADU IATAN(3), GHEORGHIȚA TOMESCU(4)
For sustainable development of the textile industry must find solutions to reduce waste and decrease noise at work. Of textile waste are obtained boards of different thicknesses, which aim to be wide field of use. For it is to achieve some experimental results about the soundproofing of plate types: is studying recoverable boards made of short textile fiber and cork boards. Textiles have a thickness of 3 mm and 10 mm and cork boards with a thickness of 3 mm and 10 mm. For determining is used the impedance tube reading Brüel&Kjaer, type 4206. By analyzing the absorption coefficient results that materials have absorbing characteristics that increase with material thickness. From these boards aims to obtain laminated composite materials used to encapsulate industrial noise sources.
STUDY CONCERNING THE MONITORING OF PARTICULATE MATTER PM2,5 AND PM10 IN THE LIBRARY OF “VASILE ALECSANDRI” UNIVERSITY OF BACAU
OANA IRIMIA(1), MIRELA PANAINTE LEHĂDUŞ(1), VALENTIN NEDEFF(1), CLAUDIA TOMOZEI(1), ALEXANDRA ŢÎRŢOACĂ(1)
Air pollution is a problem both for outdoor as well for indoor environment (working environment). The work environment is represented by ambient where the worker operates and includes the physical environment and on other part the social environment. This paper presents the results of measurements for particulate matter (PM2,5 and PM10) in a closed environment, respectively the library of “Vasile Alecsandri” University of Bacau. The measurement for particulate matter PM2,5 and PM10 in the library was performed in seven halls: two deposits for old books, two deposits for new books, newspaper deposit, reading room and computer room. After accomplishing the measurements, were established the points where the admissible limit values have been exceeded for particulate matter PM2,5 and PM10, according to law. Thus, it is observed that the permissible values were not exceeded for either PM2,5 and PM10 particulate matter in any sampling points.
APPLICATION OF MAGNETOELASTIC EFFECTS FOR STRESS ASSESMENT AND RISK MITIGATION IN CONSTRUCTIONS
DOROTA JACKIEWICZ(1), MICHAL NOWICKI(2), ROMAN SZEWCZYK(2), ADAM BIENKOWSKI(2), MACIEJ KACHNIARZ(1), JACEK SALACH(2), MARCIN KAMINSKI(1)
Stress assessment in the steel constructions is crucial for risk mitigation. NDT methods are widely used in such applications. However, many of these methods are hazardous, due to the radiation or chemicals used. The proposed magnetoelastic method is neutral to the natural environment. In this paper, development of such a method of stress assessment in constructional steel samples is presented. Measurements of the magnetic hysteresis loops of the sample members were performed under varying mechanical load on the specially designed steel truss test stand, which allowed to obtain magnetoelastic Bm(σ)Hm characteristics. The results confirm the feasibility of the new method of NDT stress assessment in the steel truss constructions.
MOTION ANALYSIS OF LIQUID PISTON ENGINES
SUNNY NARAYAN(1), VIKAS GUPTA(1)
Engines and pumps are common devices that have become important sources of power to operate machines used in everyday life. Many of these machines need complex technology for proper operation. However, some of these can be operated by using simple mechanical processes. Liquid piston fluidyne engines are such devices that are a simpler version of Stirling engines. In this work, a simple test rig using this concept has been designed. Various experiments were done to test the device, and future recommendations on improvements have been presented.
PRELIMINARY MATHEMATICAL MODEL OF A NEW ANKLE REHABILITATION DEVICE
CRISTINA RACU (CAZACU)(1), IOAN DOROFTEI(1)
Among lower limb injuries, the ankle joint is the most common injured in sports and daily life in general. Rehabilitation aims to recover the patient’s physical capabilities through long and repetitive exercises. This paper discusses structural and kinematic aspects of a novel ankle rehabilitation device, which can facilitate the recovery of the ankle joint. The proposed device has two degrees of freedom, and will ensure functionality with minimum dimensions. Some preliminary mathematical models are also presented.