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Recent 12

Vol. 5 (2004), Nr. 3 (12)

Numărul 12 al Revistei RECENT a fost:

  • realizat în colaborare cu Asociaţia Română de Tehnologii Neconvenţionale

  • editat şi multiplicat cu sprijinul:

- Universităţii "Transilvania" din Braşov

- Consiliului Judeţean Braşov (prin Comisia de Cultură, Învăţământ, Cercetare, Culte şi Muzeul Judeţean de Istorie Braşov)


CONTENTS

  • Vasile BEJAN

Culture as a spirit state and progress factor of the nation

  • Romeo CIOARĂ

A brainstorming meeting

  • Ioan CIOBANU, Sorin Ion MUNTEANU, Aurel CRIŞAN

The influence of the geometric factors on the isotherms distribution in the mould-part assembly at the solidification of U section castings

  • Florin CLOŞCĂ, Liviu HRIŢULEAC

Aspects regarding constructive unity of screw presses

  • Aurel CRIŞAN, Sorin Ioan MUNTEANU, Ioan Ciobanu

The effect of chemical composition on cast iron's hardening capability

  • Ioan DAN, Romeo CIOARĂ

Special machine tool for drilling-reaming air compressor cases

  • Ioan ENESCU

Assisted process design of hertzian contacts using numerical methods

  • Aurel FRATU, Mariana FRATU, Laura RAB, Adrian MAILAT

Adaptive control of robots

  • Virgil GEAMĂN

Containerless hot isostatic processing: technology and markets

  • Mihai IONESCU

The propagation time determination of pneumatic signals in pipes

  • Aurel LUNGULEASA

Technological devices for milling used on machines with vacuumetric work table

  • Vladimir MĂRĂSCU-KLEIN

Cost analysis in materials selection

  • Ioan MILOŞAN

The variation of the microharness in the worn layer of heat treated nodular cast iron

  • Daniel MUNTEANU

Considerations regarding the main heat treatments applied of titanium alloys (2nd Part)

  • Sorin Ion MUNTEANU, Ioan CIOBANU, Aurel CRIŞAN

Computer simulation of the solidification of U section bars

  • Adrian NEAGU

Monofactorial dispersional analysis for hot repression process Rastegaev specimens 17MoCN14 steel, in industrial conditions

  • George NICOLAE, Adrian Virgil CRĂCIUN, Mihai ROMANCA, Gheorghe PANA

Noise in TV channel. Noise measuring at TV receiver entrance (2nd Part)

  • Mircea Daniel NIŢULESCU, Alina Maria FLORESCU

PLM and PDM concepts. General presentation

  • Gheorghe PANĂ, George NICOLAE

Determination of opamps modelled parameters

  • Maria POPESCU, Elena HELEREA, Alina NEAGOE

Quality evaluation models of the higher education institutions

  • Laura M. RAB, Willibald SZABO

Analysis and investigations concerning to the electronic instruments and measurements methods for flow detection


Vasile BEJAN

CULTURE AS A SPIRIT STATE AND PROGRESS FACTOR OF THE NATION

» Abstract. The works present the main elements of culture as a whole and ways in which it can influence the evolution of the Romanian society.

» Keywords: culture, human society, social evolution


Romeo CIOARĂ

A BRAINSTORMING MEETING

» Abstract. Among the group creation techniques, the brainstorming is relatively easy to approach and can be applied do a variety of creation topics. It is an excellent technique of joining ideas and finding original solutions.
The paper confirms the attributes specific to brainstorming, the approached topic being in itself a less conventional one: shoe with adjustable heel. There are presented and then analysed the ideas exposed by the members of the
creation group, approaching in a different manner the results of individual creative effort of the participants, presented previous to the brainstorming meeting and the ideas that came up during the meeting itself.

» Keywords: brainstorming, creativity, originality, shoe with adjustable heel


Ioan CIOBANU, Sorin Ion MUNTEANU, Aurel CRIŞAN

THE INFLUENCE OF THE GEOMETRIC FACTORS ON THE ISOTHERMS DISTRIBUTION IN THE MOULD-PART ASSEMBLY AT THE SOLIDIFICATION OF U SECTION CASTINGS

» Abstract. In this paper it was studied the solidification of some bars in shape of U, cast in cast iron, by computer simulation. In that scope it was used a software created by authors. It was analysed the influence of the geometry of the section on the position of hot spots and on solidification time of these one. It was established the influence of the distance between the parallel arms of the part on the coefficient of shape that characterise the solidification.

» Keywords: cutting, workability, modelling, decision


Florin CLOŞCĂ, Liviu HRIŢULEAC

ASPECTS REGARDING CONSTRUCTIVE UNITY OF SCREW PRESSES

» Abstract. The paper analyses the possibility to manufacture different screw presses with the same or similar components. The main idea is to integrate most identical components possible in different screw presses.

» Keywords: screw press, constructive unity


Aurel CRIŞAN, Sorin Ioan MUNTEANU, Ioan Ciobanu

THE EFFECT OF CHEMICAL COMPOSITION ON CAST IRON'S HARDENING CAPABILITY

» Abstract. The paper presents research about effect of chemical composition on hardening capability of cast irons used for the casting of bearing ball machining disks. Samples (of 40 mm diameter and 300 mm length) were cast from two type of cast iron, of which test pieces were extracted, specially machined for the aims of the research, to determine hardening capability. The paper describes the type of used test pieces, working conditions and presents the interpretation of the experimental results (second degree polynomial regression curves) as well as the consequent conclusions.

» Keywords: cast iron, bearing ball machining disks, hardening capability, cast iron's casting


Ioan DAN, Romeo CIOARĂ

SPECIAL MACHINE TOOL FOR DRILLING-REAMING AIR COMPRESSOR CASES

» Abstract. For machining a great number of complex workpieces realised in large series, is efficient to use specialised machine tools. This paper present a machine destined for drilling and reaming an air compressor case.

» Keywords: compressor case, specialised machine tools, computer aided design


Ioan ENESCU

ASSISTED PROCESS DESIGN OF HERTZIAN CONTACTS USING NUMERICAL METHODS

» Abstract. Designing roller bearings it depends, from reliability point of view, by the shape of rolling element. It was studied the aspect for all rolling bearings with MathCAD software. For the determination of the tensions state and deformations, it was used ANSYS software, a finite element software with application for the roller bearings.

» Keywords: bearings, rollers, MathCAD, finite element


Aurel FRATU, Mariana FRATU, Laura RAB, Adrian MAILAT

UPGRADING OF HYDRAULIC DIRECTION CASE FOR BROADER USE

» Abstract. The practical implementation of adaptive controllers requires consideration of various sources of uncertainties such as modeling errors, computation errors, external disturbances, unknown loads, and noise. Adaptive and robust control are concerned with the problem of maintaining precise tracking under uncertainty. We distinguish robust from adaptive control in the sense that an adaptive algorithm typically incorporates some sort of on-line parameter estimation scheme while a robust control non-adaptive scheme does not. Controllers that can handle regulation and tracking problems without the need of knowledge of the process parameters are by themselves an appealing procedure. Such control schemes belong to the class of adaptive control.

» Keywords: adaptive control, adaptive gravity compensation control


Virgil GEAMĂN

CONTAINER LESS HOT ISOSTATIC PROCESSING: TECHNOLOGY AND MARKETS

» Abstract. In this paper, we will identify and discuss potentially profitable markets and applications of container less Hot Isostatic Processing (HIP’ing) and sinter/HIP of closed porosity sintered Powder Metallurgy (P/M) parts. Also, the technology of container less HIP’ing will be discussed, along with the economies of HIP’ing for various types of HIP cycles. An historical overview of the present successful applications of HIP will also be presented.

» Keywords: HIP’ing technology, P/M parts, castings


Mihai IONESCU

THE PROPAGATION TIME DETERMINATION OF PNEUMATIC SIGNALS IN PIPES

» Abstract. In this paper the author wants to determine the pressure wave propagation times through the pipe-lines necessary for the pneumatic driving and/or actuating. To achieve this goal he uses optical sensors, made by the author, an electronic computer, an appropriate computer software that is capable to record these times. The experimental data are processed using the Lillfors statistic test.

» Keywords: time propagation, sensors, data processing


Aurel LUNGULEASA

TECHNOLOGICAL DEVICES FOR MILLING USED ON MACHINES WITH VACUUMETRIC WORK TABLE

» Abstract. Technological devices for milling that are used on machines with vacuumetric table of working represent one special category of technological devices that are used in wood industry, but differentiated by its practical utility and also by its calculation and design aspects.

» Keywords: technological devices, milling device, vacuumetric table, wood milling


Vladimir MĂRĂSCU-KLEIN

COST ANALYSIS IN MATERIALS SELECTION

» Abstract. Cost is the basis to which the above factors are reduced to reach a decision on material selection. In the technical cost modeling technique, variable and fixed costs are calculated separately. Variable costs are those costs that can be directly associated with the production of a unit of output and whose total increases roughly linearly with the total number of units produced. The material cost can be estimated as a function of the price of the raw materials, the design of the component and scrap considerations associated with the process. Essentially, the problem is one of determining the total amount of material actually required by each part, realizing that there will be material losses due to the process and part losses due to quality control.

» Keywords: materials selection, cost analysis, analytical methods


Ioan MILOŞAN

THE VARIATION OF THE MICROHARNESS IN THE WORN LAYER OF HEAT TREATED NODULAR CAST IRON

» Abstract. The microhardness of bainitic nodular cast iron under different isothermal time and abrasive wear, were study in the present paper. The influence of the technological parameters of heat treatment and abrasive wear has also been studied.

» Keywords: bainitic nodular cast iron, abrasive wear, microhardness


Daniel MUNTEANU

CONSIDERATIONS REGARDING THE MAIN HEAT TREATMENTS APPLIED OF TITANIUM ALLOYS (2nd PART)

» Abstract. The response of titanium and titanium alloys to heat treatment depends on the composition of the metal and the effects of alloying elements on the α – β crystal transformation of titanium. In addition, not all heat-treating cycles are applicable to all titanium alloys, because the various alloys are designed for different purposes. The main objective of this paper include a general description of the characteristics of Ti alloys and the possibilities to heat treating by solution treating and aging in order to affect their mechanical behaviour which can dictate the optimal conditions under which they can be efficiently used.

» Keywords: titanium alloys, heat treatments, mechanical properties


Sorin Ion MUNTEANU, Ioan CIOBANU, Aurel CRIŞAN

COMPUTER SIMULATION OF THE SOLIDIFICATION OF U SECTION BARS

» Abstract. The paper presents a 2D mathematical model, based on finite differences method and software created by authors, to simulate the solidification of castings with translation symmetry. There are presented the hypotheses that are on the basis of the model. There are presented too the conditions of application of the program to study the solidification of bars with U section, as well as the parameters that can be analysed using this program.

» Keywords: mathematical model, solidification, simulation


Adrian NEAGU

MONOFACTORIAL DISPERSIONAL ANALYSIS FOR HOT REPRESSION PROCESS RASTEGAEV SPECIMENS 17MOCN14 STEEL, IN INDUSTRIAL CONDITIONS

» Abstract. In this paper is presented an experimentation programme for the monofactorial dispersion analysis with a view to selecting some technological parameters typical of the hot compression process for Rastegaev specimens 17MoCN14 steel, in industrial conditions. There are analysed the individual influences of two main geometrical parameters of the specimens about the friction conditions of the repression process between plane-parallel surfaces.

» Keywords: plastic deformation, compression process, technological parameters, dispersion analysis


George NICOLAE, Adrian Virgil CRĂCIUN, Mihai ROMANCA, Gheorghe PANA

NOISE IN TV CHANNEL. NOISE MEASURING AT TV RECEIVER ENTRANCE (2nd PART)

» Abstract. Statistics and probability calculus may be used in television to characterize noise in TV channels. This paper presents the experimentally results of noise measuring at TV receiver input. The paper first introduces the most important concepts in statistics and probability, emphasizing how they apply to acquired signals and noise. The data acquisition system was used to measure various parameters of fluctuation noise at TV receiver entrance. These parameters are important in understanding the noise influence on the quality of received images. The experimentally measurements were concentrated onto determining the characteristics of the noise in UHF frequency band TV channels.

» Keywords: radio communications measuring system noise, noise in TV channel, fluctuation noise


Mircea Daniel NIŢULESCU, Alina Maria FLORESCU

PLM AND PDM CONCEPTS. GENERAL PRESENTATION

» Abstract. The paper presents the two convergent concepts – Product Lifecycle Management and Product Data Management – and the benefits and disadvantages that appear by implementing these concepts. The paper also shows the possible ways to follow in the future and how to adapt the engineering activity to the specific economical and social conditions.

» Keywords: PLM, PDM, Knowledge


Gheorghe PANĂ, George NICOLAE

DETERMINATION OF OPAMPS MODELLED PARAMETERS

» Abstract. Circuit simulation by computer (SPICE simulation) has become a powerful and indispensable tool in both circuit analysis and design. This paper presents the identification of op amp parameters based on the SPICE model from libraries.

» Keywords: opamp, SPICE, model


Maria POPESCU, Elena HELEREA, Alina NEAGOE

QUALITY EVALUATION MODELS OF THE HIGHER EDUCATION INSTITUTIONS

» Abstract. The paper presents the evaluation models of the Higher Education Institutions, instruments of the quality management systems. The main objectives of the study are to analyse the evaluation models applied in the Romanian universities after the implementation of the quality management, and to establish the actions in order to improve the effectiveness of the quality evaluation models.

» Keywords: Quality Management, accreditation, evaluation procedures, EFQM model


Laura M. RAB, Willibald SZABO

MONOFACTORIAL DISPERSIONAL ANALYSIS FOR HOT REPRESSION PROCESS RASTEGAEV SPECIMENS 17MOCN14 STEEL, IN INDUSTRIAL CONDITIONS

» Abstract. Flow meters and their metrological characteristics represent one of the widest and most complex sectors of measurement instrumentation for industrial use. This paper deals with some investigations concerning measurements methods for flow detection. For three measurements methods, the experimental results have been comparing, in order to obtain a good accuracy. In the final part, the paper presents the main aspects regarding the structure of the measuring system and the solutions applied.

» Keywords: flow detection, flow metering instrumentation, measurements


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