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  Numar curent

Volumul 14 (2023), Nr. 4 - Vizualizare numar complet

Iluminatul centrat pe ocupant (OCL) pentru bunastare: o revizuire
Occupant-Centred Lighting (OCL) to well-being: a review
M Simtinica, M Husch, S Caluianu

People in the past spent most of their time outdoors and received the benefits of exposure to natural light. Nowadays we spend a large part of our day indoors where we predominantly use artificial lighting. Against the backdrop of the accelerating climate change we are experiencing, the need to reduce energy consumption in the lighting component of buildings can be achieved by maximising the use of natural daylight during the day in conjunction with identifying the human presence in indoor spaces for efficiency. Occupant Lighting Control technologies offer a real tool to achieve these goals. Adaptive lighting automation controllers, sensor networks and wireless actuators for occupancy-based lighting control, user-centric lighting control based on video cameras, platforms for intelligent lighting control based on life logs are just some of the techniques and methods used to apply Occupant Lighting Control principles. Although lowering energy consumption in buildings is the primary goal of lighting management systems, taking into account the inhabitants' feeling of comfort and their general level of wellbeing is just as vital, if not more so. The adoption of integrative lighting, by complementing natural light with artificial lighting in an articulated manner and in conjunction with the human presence in interior spaces, is the efficient and humanaccepted path to sustainable energy efficiency. A collective effort by society is needed to make human-centred lighting an everyday reality.

Keywords: Lightning, services, natural light

Controlul instrumentatiei virtuale pentru evaluarea si compensarea operatiunilor dezechilibrate ale retelei trifazate
Virtual instrumentation control for evaluation and compensation of the three-phased grid’s unbalanced operations
Robert Pecsi, Magdalena Culcea, Eleonora Darie and Elena Sanda

The unbalanced operation of the three-phase grid has a large number of negative consequences. The solution to this problem of unbalance, problem that appears whenever an unbalanced or single-phase load is connected to the network can be based either on conversion, or on compensation. Compensation based methods are capable of compensating not only the unbalanced operations, but also the non-sinusoidal and reactive operations. Former papers of the authors study the compensations methods. In this paper there is developed a LabView virtual instrument capable to calculate the unbalance factor of the grid and to control the active power filter used for compensation. The developed virtual instrument enables the activation of the compensation depending on the values of the measured and calculated unbalance factor. The method compensates the nonsinusoidal, reactive and unbalanced operations of the three-phase grid. Measurements prove the instrument’s efficient operation and the method’s viability.

Keywords: Virtual instrumentation, three phased grid

Spuma de geopolimer pe baza de cenusa zburatoare de carbune si metacaolin ca un material de constructie poros, economic si ecologic
Geopolymer foam based on coal fly ash and metakaolin as an economic and environment friendly porous construction material
Lucian Paunescu, Bogdan-Valentin Paunescu, Enikő Volceanov

O spuma de geopolimer pe baza de cenușa zburatoare si metacaolin a fost proiectata si testata. A fost aplicata tehnica uzuala de activare a materialelor aluminosilicatice in mediu inalt alcalin, generarea geopolimerului fiind favorizata prin desfasurarea reactiei de geopolimerizare. Agentul traditional de spumare (peroxid de hidrogen) a fost inlocuit cu perborat de sodiu, mai stabil si mai ușor de manipulat. Originalitatea lucrarii a fost utilizarea unui nanomaterial (argila de bentonita), avand capacitatea cresterii rezistentei mecanice. Densitatea si conductivitatea termica ale noului produs au avut valori reduse (470 kgꞏm-3 și 0,104 Wꞏm-1ꞏK-1), iar rezistența la compresiune a atins 7,5 MPa.

Cuvinte Cheie: spuma de geopolimer, geopolimerizare, perborat de sodiu, nanomaterial, proprietati termoizolante.

Geopolymer foam based on fly ash and metakaolin was designed and tested. The usual technique of activating alumino-silicate materials in a highly alkaline medium was applied, the generation of the geopolymer being favoured by developing the geopolymerization reaction. The traditional foaming agent (hydrogen peroxide) has been replaced by sodium perborate, which is more stable and easier to handle. The work originality was the use of a nanomaterial (bentonite clay), having the ability to increase the mechanical strength. Density and thermal conductivity of the new product had low values (470 kgꞏm-3 and 0.104 Wꞏm-1ꞏK-1) and compressive strength reached 7.5 MPa.

Keywords: geopolymer foam, geopolymerization, sodium perborate, nanomaterial, thermal insulating properties.

Corelatii intre incercarile geotehnice de teren si parametrii geotehnici ai stratului Lutul de Bucuresti
Correlations between geotechnical in situ investigations and geotechnical parameters of the Bucharest Loam layer
Alexandru Poenaru

The in situ geotechnical investigation methods are experiencing an upward trend in their use at national and international level. In the international literature there are numerous correlations between in situ tests and geotechnical parameters which have been developed mainly in Western European countries, the United States and Japan. This paper contributes to a better understanding of how to select, interpret and apply correlations between geotechnical soil parameters and in situ test results for the Bucharest Loam layer. New correlations between CPT and DMT tests and routine laboratory tests for the Bucharest Loam layer were developed.

Keywords: Correlations, CPT, DMT, Bucharest Loam

Analiza termica a unui rezervor de stocare
Thermal analysis of storage tank PCM
Emilian-Florin Turcanu, Vasilica Ciocan, Nelu-Cristian Chereches, Sebastian-Valeriu Hudisteanu, Ana Diana Ancas, Verdes Marina, Catalin-George Popovici

In this research, we investigate the thermal behavior of storage tanks subjected to varying environmental conditions. Through numerical simulations and experimental analysis, we assess heat transfer mechanisms, temperature distribution, and energy consumption patterns of both insulated and non-insulated tanks. Our study aims to optimize tank design and insulation materials to minimize heat losses, improve energy efficiency, and enhance the safety and longevity of storage tanks. Findings reveal that incorporating optimal insulation materials and techniques can significantly reduce energy consumption and maintain the desired temperature range within the tank, thus providing valuable insights for future storage tank design and management.

Influenta climatului interior asupra performantei umane. Studiu de caz
Indoor climate influence related human performance. Case Study
Cristian Pacurar, Adriana Tokar, Marius Adam

The indoor air quality is one of the main factors that influence the thermal confort and, consenquently, the human performance inside buildings. Throughout the years, a lot of studies described the relation between the climate confort and the performance .This study follows the thermal sensations of students in a seminar room during the summer and winter periods and presents the results between them.

Keywords: thermal comfort, productivity, performance, PMV, PPD, environmental comfort, indoor environment1. Introduction

Sisteme de menținere a alimentarii cu energie electrica pentru protectie la incendiu
Power supply insurance solutions for fire protection
Catalin Dragota, Adriana Tokar, Alexandra Rusen

The study analyzes the benefits of implementing automatic transfer systems of the main electricity supply with one or more backup supplies in the event of a breakdown caused by a fire or other unforeseen events. Transfer switch using relays as phase failure protection is a gear switch control system with the main purpose of transferring load between a primary source (Public Utility) and a secondary power supply sources (Generator1 and Generator2) which are stand by power sources and eliminating frequent manual switching of change over device when there is power outage.

Keywords: backup supplies, fire, control system, maintenance

Parametrii energetici ai elementelor de constructie in conceptul de casa pasiva
Energy parameters of construction elements in the passive house concept
Alexandra Rusen, Danut Tokar, Catalin Dragota

Newly built houses are subject to requirements with high levels of energy performance including the creation of houses with zero energy consumption (passive houses) and respectively without carbon emissions. Building regulations, processes and control will need to be rethought in light of these ambitions and a development of performance guarantees in the construction sector.Many mandatory standards and rating systems for the energy efficiency of buildings have been developed globally, but those for passive houses are still voluntary, and for this reason there is little data on the performance of houses built to these standards. They have emerged as a promising approach to mitigating and solving many energy problems, and constructive visions and solutions and testing or demonstrating their feasibility are undoubtedly major steps in the process of solving the energy problem.

Keywords: passive house, energy parameters, performance of materials, operational costs

Termografia – noi tendinte in inspectia instalatiilor de incalzire
Thermography – new trends in heating installation inspection
Viorica David, Alina-Corina Bala, Floarea - Maria Brebu, Maria - Roberta Jianu

Technology is always evolving at a quick rate and specialists try to integrate it in their works, either if we are discussing engineering, or any other domain. Furthermore, the most important accomplishments, in a research domain, are achieved when using the latest technology and research interdisciplinary. So, starting from all the above, in this paper we are trying to create a connection between monitoring methods and technologies, used in Thermography, and the installation inspection which is a part of Building Services. Data was acquired from thermal images and processed to establish the integrity of a heating installation.

Keywords: thermography, thermal images, heating installations, thermal inspection, clogged pipes

Aspecte teoretice si experimentale privind gestionarea sustenabila a apelor meteorice intr-un ansamblu rezidential
Theoretical and Experimental Aspects of Sustainable Rainwater Management in a Residential Area
Andrei Bolboaca, Dan Muresan, Anagabriela Deac, Cristina Iacob, Teodor Chira

In the paper, the authors address the issue of rainwater management, which represents a renewable, clean, and cost-free resource. However, currently, the way to reintroduce it into the environment is not sustainable because it is done with high energy consumption and at significant expenses. The case study presents a solution whereby, with a small investment, rainwater is returned to the natural water cycle in nature

Keywords: rainwater, rainwater management, circular economy

Cauze si consecinte ale evenimentelor de munca in intreprinderile de instalatii electrice si tehnico-sanitare din judetul Timis
Causes and consequences of work events in electrical and technical-sanitary installation enterprises from Timis County
Rudolf Mirescu, Dumitru Tucu

The paper identifies and hierarchize all factors and causes of work events in the field of enterprises specialized in building facilities and environmental comfort, from Timiș County, considered as integrated part in the process of optimization of specific occupational health and safety risk management systems (OHSRMS). Based on activities (CAEN code 4321 and 4322), the work events from the last 10 years were extracted from official statistics, correlated with number of employees, factors and causes (also, special conditions). 1397 enterprises were selected. The relevance was verified by Fisher test and ANOVA, and possible relations based on work events were identified.

Keywords: work accident/event, optimization, occupational health and safety risk management system

Adaugarea unui deseu agricol in amestecul pentru fabricarea betonului geopolimeric pentru constructii
Agro-waste addition in the mixture for building geopolymer concrete manufacture
Bogdan Valentin Paunescu, Lucian Paunescu, Eniko Volceanov

Betonul geopolimeric pe baza de cenusa zburatoare incluzand un deseu agricol (cenusa de stiulete de porumb) a fost ales ca varianta optima ca urmare a experimentului in care zgura granulata de furnal a fost de asemenea utilizata in celelalte variante. Solutia de activator alcalin pentru dezvoltarea reactiei de geopolimerizare a fost mentinuta. De asemenea, tehnica uzuala de intarire a fost aplicata pentru cresterea rezistentei mecanice. Proba de beton geopolimeric cu adaosul cenusii de stiulete de porumb produs in varianta optima a avut urmatoarele caracteristici: densitatea-2369 kgꞏm-3, porozitatea-34,8 %, conductivitatea termica-0,509 Wꞏm-1ꞏK-1, rezistenta la compresiune-25,9 MPa (după 7 zile) si 39,8 MPa (după 28 zile)

Cuvinte Cheie: beton geopolimeric, deseu agricol, cenusa de stiulete de porumb, deseu aluminosilicatic, activator alcalin

Geopolymer concrete based on fly ash including an agro-waste (corn cob ash) was chosen as the optimal version as a result of the experiment in which granulated blast furnace slag was also used in the other versions. The alkaline activator solution for developing the geopolymerization reaction was kept. Also, usual curing technique was used to increase the mechanical strength. The geopolymer concrete specimen with corn cob ash addition made in the optimal version had the following features: density-2369 kgꞏm-3, porosity-34.8 %, heat conductivity-0.509 Wꞏm-1ꞏK-1, compressive strength-25.9 MPa (after 7 days) and 39.8 MPa (after 28 days).

Keywords: geopolymer concrete, agro-waste, corn cob ash, alumino-silicate waste, alkaline activator.

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