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  Numarul 1/2020

Volumul 11 (2020), Nr. 1 - Vizualizare numar complet

Aspecte privind predictia coroziunii electrozilor de pamantare in solul municipiului Timisoara Partea a III-a. Predicția matematică a coroziunii
Aspects regarding the corrosion prediction of earth electrodes in the soil of the municipality of Timisoara Part III. The mathematical prediction of corrosion
Stefan PAVEL, Ioan-Bogdan PASCU, Bogdan-Ovidiu TARANU, Oana-Alexandra GRAD, Romeo NEGREA

Predictia coroziunii electrozilor de pamantare instalati in solul din orasul Timisoara

Cuvinte cheie: sol, electrod de impamantare, coroziune, predictie

Corrosion prediction of galvanized steel ground electrodes in the soil of Timisoara

Keywords: soil, earth electrode, corrosion, prediction

Innovation of pneumatic waste in building sound insulation systems against internal and external noise

After the experiment of the same material in thermal insulation, the present work is a new investigation to answer the problem of acoustic comfort of the constructions while clearing the environment of the pneumatic waste which by their long life occupy large spaces and by their incineration emit polluting gases. Numerous tests have been carried out on reduced or real models representing either the floors or partition walls that are the main conductors of sound in a building. In comparison with the expensive materials currently used in acoustic insulation, the proposed innovation has shown unexpected technical sound insulation performances accompanied by a great economic interest.

Keywords: Acoustic Insulation, Noise, Acoustic Vibration, Building, Pneumatic waste.

Case study regarding the energy efficiency of green buildings envelope
Georgiana Corsiuc, Carmen Marza

Green buildings must use materials with a positive impact on the human being and environment while ensuring a high degree of thermal insulation. The structure of the exterior wall proposed by the authors was designed to meet as many requirements as possible: to have good insulating properties and a proper behavior to the diffusion of vapors, to comply with the requirements imposed by regulations regarding the thermal stability of the construction elements, to use environmentally friendly materials and also to have a light weight so that it can be prefabricated or used in modular constructions that require transport and manipulation.

Randamentul captatorului solar plan. Forma pătratică, aspecte teoretice
Flat plate solar collector efficiency. Theoretical aspects of the quadratic form
drd. ing. Alexandru Drăghici, prof. dr. ing. Florin Iordache

In lucrare se prezintă rezultatele obţinute in urma unei simulări numerice a proceselor de captare a radiaţiei solare şi transfer termic aferente unui captator solar cu placă absorbantă plană. Parametrii de bază urmăriţi sunt coeficientul global de transfer termic aferent captatorului solar (kC) şi randamentul de captare (niuC). S-au avut in vedere procesele de transfer termic convectiv şi radiant intre placa absorbantă şi elementul transparent. Rezultatele obţinute sunt prezentate grafic şi comentate.

This paper presents the results of a numerical simulation concerning the solar radiation collecting and heat transfer processes associated with a flat plate solar collector. The main studied parameters are the overall heat transfer coefficient of the collector (kC) and the collecting efficiency (niuC). During the simulation, convective and radiative heat transfer processes between the absorbent plate and glazing have been considered. The obtained results are graphically presented and commented.

Mechanical properties of high-performance concrete made incorporating dune sand as fine aggregate.
Fatima Zahra Rennani, Abdelkadir Makani, Noureddine Agha, Ahmed Tafraoui, Farid Benmerioul, Said Zaoiai

The main objective of this research is to contribute to an experimental study of the behavior of high-performance concrete (HPC) based on dune sand of Taghit (Bechar-Algeria). This work also optimizes the formulation of HPC based on local materials. We used Taghit's dune sand to formulate HPC as fine sand substituting the fine amount of quarry sand fines. This substitution makes it possible to improve the distribution of the granular skeleton, the microstructure (size and network of the pores), the mechanical strength of the hydrated cement pastes in the short and long term, and consequently the performances of these concretes. The results show that the modification of sand quarry (0 <0.315) by dune sand in the composition of HPC Contributes to a slight improvement of properties in the fresh state. The mechanical behavior (strength and compressive modulus of elasticity) increased slightly with control concrete (about 5%) at 28 days for all proportions (25%, 50% and 100%). Finally, we can say that our study has shown that it is possible to realize a HPC based on dune sand, and that the development of dune sand can provide a solution for some work in the desert regions.

Keywords: High-Performance Concrete, Dune sand, Compressive strength, Modulus of elasticity

Analiza și estimarea parametrilor care influențează temperaturile stratului de gaze fierbinți intr-un compartiment de incendiu, in funcție de sistemul de ventilație folosit
Analysis and estimation of parameters influencing hot gas layer temperatures in a fire compartment as a function of the type of the ventilation system
Alexandra TEODOR, Alexandru-Florin CHIOJDOIU, Octavian LALU, Ion ANGHEL, Aurel TROFIN, Ionel Alin MOCIOI,Liviu-Valentin BALANESCU

In acest studiu s-au utilizat metode empirice de estimare a temperaturilor stratului de gaze fierbinți intr-un compartiment de incendiu cu dimensiuni standardizate. S-au impus o serie de ipoteze și limitări metodelor utilizate, in baza cărora au fost analizate două scenarii de incendiu, și anume: compartimentul de incendiu, ale cărui suprafețe interioare sunt căptușite, pe rind, cu PAL, ghips carton, polistiren și beton, arde și este ventilat in două moduri diferite: ventilație naturală și, respectiv, ventilație mecanică. De asemenea, s-a considerat că valoarea fluxului de căldură degajat (HRR) este constantă, aceasta luand, pe rand, valorile de 250 KW, 500 KW ܹ݇și, respectiv, 1000 KW. Prin utilizarea Fire Dynamics Tools (FDTs) dezvoltat de US Nuclear Regulatory Commission [11], s-au obținut diagrame ale temperaturii stratului de gaze fierbinți și s-a efectuat o analiză comparativă a rezultatelor obținute. Astfel, s-a constatat că valorile de temperatură din stratul de gaze fierbinți degajate intr-un compartiment in urma unui incendiu sunt influențate de o serie de parametri, cum ar fi: proprietățile termice ale finisajelor interioare, fluxul de căldură degajat, geometria compartimentului de incendiu, sistemul de ventilație utilizat. in cadrul Facultății de Pompieri a fost creat un astfel de compartiment de incendiu, care urmează să fie folosit pentru teste experimentale in scopul validării rezultatelor empirice, estimate cu FDT6 in prezentul articol.

In this study, some empirical methods were used to estimate the temperatures of the hot gas layer in a fire compartment with standardised dimensions. A number of assumptions and limitations were imposed on the methods used, on the basis of which two fire scenarios were analysed, namely: the fire compartment, whose inner surfaces are lined, successively, with chipboard, gypsum board, expanded polystyrene and concrete is natural ventilated, respectively mechanically ventilated. It was also considered that the value of the heat release rate (HRR) is constant, with values of 250 kW, 500 kW and 1000 kW. By using the Fire Dynamics Tools (FDTs) developed by the US Nuclear Regulatory Commission [11], diagrams of the temperature of the hot gas layer were obtained and a comparative analysis of the results was performed. Thus, it was found that the temperature values of the hot gas layer released in a fire compartment are influenced by a number of parameters, such as: the thermal properties of the interior finishes, the heat release rate, the geometry of the fire compartment, respectively the ventilation system that was used. On the premises of Fire Safety Engineering Faculty, one such a fire compartment was built. In the fire compartment. This fire compartment will be used for, experimental tests that are to be conducted in order to validate the empirical results initially estimated with FDT6.

Hydromechanical coupling in the soil-structure interaction
Belbekri M., Draoui B., Berga A.

Historically,in civilengineering construction,the structural design takes account the gravity, overloadand waterpressure as fundamental forces. Becomes later the consideration of the dynamics effects as the machine vibration and the earthquake,the fire resistance...etc. After all,the survey of projects like building,road,pavement ‐asexample‐ show that there is always appearance of various anomalies and damages that are evolutionary in time. Often,they can be due to the watercycle.The paper handles the hydromechanical couplingcase,shows how conducting the analysis and proof the feasibility of the structural design in these conditions.The results are obtained in the frame of the finite element analysis and they open the horizon for more improvements.

Keywords: Soil, structure, water, hydromechanical, interaction, Finite element method

Impactul climatic al particulelor atmosferice; Studiu de caz pentru municipiul București
Climatic impact of atmospheric particles; Case study for Bucharest municipality
Florinela Ardelean

Emisiile rezultate din transportul rutier participă direct şi indirect la schimbările climatice resimţite la nivel local, regional şi planetar. Aerosolii solizi și lichizi influențează troposfera urbană din punct de vedere fizico-chimic, modifică bilanțul radiativ inregistrat la nivelul suprafeței terestre și atmosferei, afectează biosfera și implicit sănătatea umană. Folosindu-se o bază de date formată din valorile medii orare ale concentrației de particule PM10, corespunzătoare anilor 2018 și 2019, se va analiza calitatea aerului in București in stransă legătură cu indicii specifici, atat in perioada rece cat și in cea caldă. Se vor identifica intervalele de timp din zi in care potențialul de poluare crește semnificativ. Datele astfel obținute se pot folosi in elaborarea unor strategii de protecție a atmosferei prin măsuri de amenajare a teritoriului.

Emissions resulted from road transport participate directly and indirectly to climate changes felt at local, regional and planetary levels. Solid and liquid aerosols influence the urban troposphere from a physical and chemical perspective, modify the radiative balance recorded at the earth's surface and atmosphere, and affect the biosphere and implicitly human health. Using a database created from hourly average values of PM10 particles concentrations, corresponding to 2018 and 2019, air quality in Bucharest will be analyzed in strong connection with specific indices, in the cold as well as hot periods. Certain time intervals within the day, in which pollution potential increases significantly, will be identified. The data obtained can be used in elaborating an atmosphere protection strategy with landscaping measures

Securitatea datelor in instalații fixe de alimentare ale sistemului de tracțiune electrică feroviară
Data security in fixed power installations of the railway electric traction system
Cristina Gabriela Sărăcin

Această lucrare prezintă o soluție viabilă pentru securitatea datelor in cadrul instalațiilor fixe de alimentare ale sistemului de tracțiune electrică feroviară. Transmiterea informațiilor din proces către structurile de control, supraveghere și achiziții de date (SCADA) se face prin rețeaua locală privatăși prin rețeaua publică(servere cloud). in aceste condiții, devine posibil accesul persoanelor neautorizate la rețeaua feroviară. Avand in vedere acest aspect, lucrarea pune accentul pe managementul distribuitorilor de energie feroviarăși metodele lor de securitate date. Pentru fiecare echipament este identificat nivelul său de accesibilitate rezultat din gradul de vulnerabilitate. Avand in vedere acest aspect, trebuie luate măsuri de securitate a datelor pentru a preveni potențialele consecințe negative asupra sistemului informatic. Atacurile cibernetice asupra rețelei de calculatoare din cadrul dispeceratelor feroviare pot avea loc intern (SCADA) și extern (protocoale și transmisii de date). Securitatea informațiilor, in contextul managementului traficului de date in timp real din cadrul dispeceratului energetic feroviar, conduce la creșterea nivelului de protecție al infrastructurilor critice naționale și europene.

This paper presents a viable solution for data security within the fixed power installations of the railway electric traction system. Transmission of process information to control, surveillance and data acquisition structures (SCADA) is done through the private local network and the public network (cloud servers). Under these conditions, unauthorized persons access to the railway network becomes possible. With this in mind, the paper focuses on the management of railway power distributors and their security methods. For each equipment, its level of accessibility resulting from the degree of vulnerability is identified. Therefore, data security measures must be taken to prevent potential negative consequences for the computer system. Cyber attacks on the computer network within the railway dispatchers can take place internally (SCADA) and externally (protocols and data transmissions). Information security, in the context of real-time data traffic management within the rail energy dispatcher, leads to an increase in the level of protection of national and European critical infrastructures.

Determinarea numerică a campului bidimensional de temperatură intr-o regiune plană in regim termic staţionar rezolvată in Microsoft Excel
Numerical determination of the temperature two-dimensional field in a plane region in stationary thermal solution resolved in Excel Microsoft
Şef lucr. Dr. ing. Gelu-Adrian CHISĂLIŢĂ

Lucrarea prezintă o modalitate de construcție şi utilizare a unui instrument software pentru determinarea numerică a distribuţiei temperaturii intr-o regiune plană de formărectangulară, considerand transmiterea căldurii in regim termic staţionar printr-un corp fără surse interioare de căldurăşi cunoscand temperaturile pe suprafeţele delimitatoare ale acestuia. Ca metoda de lucru principală este folosită metoda calculului cu diferenţe finite (MDF) rezolvarea sistemului de ecuaţii liniare fiind efectuată cu ajutorul instrumentului Solver din aplicaţia software Microsoft Excel aparținand suitei Microsoft Office

The paper presents the construction and use of a new software tool for numerical analysis of the two-dimensional temperature distribution in a flat region of rectangular shape of a body with constant thermal conductivity and no generation, when the temperatures on the bounding surfaces of the body are known. The finite difference method (FDM) is used to solve the system of linear equations by properly calling the Solver tool from the Microsoft Excel software application.

Studiu comparativ pentru alimentarea cu agent termic a unui bloc de locuinte
Comparative study for the supply of a block of flats with thermal agent
Constantin CILIBIU

Lucrarea prezintă un studiu de caz pentru alimentarea cu agent termic a unui bloc de locuințe ce este alimentat in prezent prin intermediul unei centrale termice de bloc, aceasta deservind intreaga clădire. Analiza se face pentru două soluții tehnice distincte, prima optiune fiind reabilitarea și modernizarea centralei termice existente, iar cea de-a doua soluție fiind cu montarea unor centrale individuale de apartament.

The paper presents a case study for the supply of thermal agent to a housing block that is currently powered by a block thermal power station, serving the entire building. The analysis is done for two distinct technical solutions, the first option being the rehabilitation and modernization of the existing thermal power station, and the second solution is with the installation of individual apartment plants.

Comportamentul termic dinamic al unui sistem activ de preparare a apei calde utilizand energia solară
Dynamic thermal behavior of an active hot water preparation system using solar energy
drd. ing. Alexandru Drăghici, prof. dr. ing. Florin Iordache

Lucrarea are ca obiectiv modelarea şi simularea comportamentului termic dinamic al unui sistem neconvenţional ce utilizează energie solară pentru alimentarea unui consumator de apă caldă menajeră. Sistemul este compus dintr-un rezervor de acumulare şi o buclă solară, care conţine suprafaţa de captare a energiei solare şi schimbătorul de căldură imersat in rezervor. Suplimentar, sistemul include o vană cu trei căi şi o conductă de ocolire a rezervorului, in vederea reglării temperaturii apei calde furnizate la consumator. in final, se urmăreşte optimizarea constructivă a sistemului neconvenţional.

The main objective of this paper is to model and simulate the dynamic thermal behavior of an unconventional system that uses solar energy for supplying a domestic hot water consumer.The system is composed of a water tank and a solar loop, containing the solar energy collecting surface and a heat exchanger sunk in the tank. Moreover, the system includes a three way valve and a pipe which bypasses the water tank, with the purpose of controlling the temperature of the delivered hot water. Finally, the constructional optimization of the unconventional system is targeted.

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