APPLICATION OF AHP TO INVENTORY MANAGEMENT AND COMPARISON TO CROSS ANALYSIS

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Thermal characterization of recycled materials for building insulation

The building sector is known to have a significant environmental impact, considering that it is the largest contributor to global greenhouse gas emissions of around 36% and is also responsible for about 40% of global energy consumption. Of this, about 50% takes place during the building operational phase, while around 10–20% is consumed in materials manufacturing, transport and building construction, maintenance, and demolition. Increasing the necessity of reducing the environmental impact of buildings has led to enhancing not only the thermal performances of building materials but also the environmental sustainability of their production chains and waste prevention. As a consequence, novel thermo-insulating building materials or products have been developed by using both locally produced natural and waste/recycled materials that are able to provide good thermal performances while also having a lower environmental impact. In this context, the aim of this work is to provide a detailed analysis for the thermal characterization of recycled materials for building insulation. To this end, the thermal behavior of different materials representing industrial residual or wastes collected or recycled using Sardinian zero-km locally available raw materials was investigated, namely: (1) plasters with recycled materials; (2) plasters with natural fibers; and (3) building insulation materials with natural fibers. Results indicate that the investigated materials were able to improve not only the energy per-formances but also the environmental comfort in both new and in existing buildings. In particular, plasters and mortars with recycled materials and with natural fibers showed, respectively, values of thermal conductivity (at 20 °C) lower than 0.475 and 0.272 W/(mK), while that of building materials with natural fibers was always lower than 0.162 W/(mK) with lower values for com-pounds with recycled materials (0.107 W/(mK)). Further developments are underway to analyze the mechanical properties of these materials

Ventilation strategies to minimise the airborne virus transmission in indoor environments

A key challenge to fight the Covid-19 pandemic is to minimise the airborne transmission of the SARS-CoV-2 virus. Highly crowded indoor environments, such as schools, become possible hotspots for virus spreading because the basic non-pharmaceutical mitigation measures applied until now are not effective in reducing the virus airborne transmission mode, which is the principal one in indoor environments and requires improved ventilation. In the present study, a mass balance equation was applied to typical school scenarios to evaluate (i) required air exchange rates for mechanically-ventilated classrooms and (ii) adequate airing procedures for naturally ventilated classrooms. In the case of naturally ventilated classrooms, a feedback control strategy was evaluated using the measurements of indoor CO2. Our results show how these procedures can be applied in real life to support continued in-person instruction during a pandemic.publishedVersio

Computational Model For The Estimation Of Thermo-Energetic Properties In Dynamic Regime Of Existing Building Components

The guidelines of the European community towards a low-carbon economic society identify one of the most important scenarios in the energy efficiency of existing buildings. The discrepancy between the requirement and availability of free heat (endogenous heat, solar radiation) in certain hours of the day and operating conditions, makes the steady-state hypothesis generally inappropriate. In particular, the oscillating component of the transmitted flow, compared to the average temperature difference, is regressive in winter and dominant in summer. From this it follows the reliability of the stationary forecast models in winter and the need for dynamic forecast models in summer. The dominance of the continental climate in the EU, compared to the Mediterranean one, led to the actual delay in the development of dynamic models, especially at a regulatory level. In this paper, a methodology for assessing the dynamic properties of a building component is evaluated. The methodology, based on heat transmission equations implements a numerical model for existing building components whose input data can be obtained from experimental measurements. The developed model has been used to estimate the energetic and thermal behaviour of a building envelope subjected to energy efficiency measure

Modeling and simulation of an assembly line: A new approach for assignment and optimization of activities of operators

In the paper we will suggest an approach based on modeling and simulation for the assignment of activities to the operators of a flexible assembly line. Thanks to the above approach, it will be possible to optimize the workload of each operator, in particular to reduce nonvalue and increase saturation. Through the adoption of a specific modeling logic, we can simulate lines with high flexibility of manufacturing and assembly, in various industrial sectors. Starting from the analysis of a real case and following an incremental approach, a simulation model has been realized, verified and validated, which allows to obtain useful information about: production mix; percentages of saturation; lead time and optimization of the assembly line. Copyright © (2011) by CAL-TEK S.r.l

Exposure to submicron particles and estimation of the dose received by children in school and non-school environments

In the present study, the daily dose in terms of submicron particle surface area received by children attending schools located in three different areas (rural, suburban, and urban), characterized by different outdoor concentrations, was evaluated. For this purpose, the exposure to submicron particle concentration levels of the children were measured through a direct exposure assessment approach. In particular, measurements of particle number and lung-deposited surface area concentrations at "personal scale" of 60 children were performed through a handheld particle counter to obtain exposure data in the different microenvironments they resided. Such data were combined with the time-activity pattern data, characteristics of each child, and inhalation rates (related to the activity performed) to obtain the total daily dose in terms of particle surface area. The highest daily dose was estimated for children attending the schools located in the urban and suburban areas (>1000 mm2), whereas the lowest value was estimated for children attending the school located in a rural area (646 mm2). Non-school indoor environments were recognized as the most influential in terms of children's exposure and, thus, of received dose (>70%), whereas school environments contribute not significantly to the children daily dose, with dose fractions of 15-19% for schools located in urban and suburban areas and just 6% for the rural one. Therefore, the study clearly demonstrates that, whatever the school location, the children daily dose cannot be determined on the basis of the exposures in outdoor or school environments, but a direct assessment able to investigate the exposure of children during indoor environment is essential.</p

Study and modelling of very flexible lines through simulation

The present paper proposes the development of a virtual model simulating an assembly line. Starting from the analysis of the real line, through an incremental approach, a simulation model is created, verified and validated, in order to obtain useful information about: • productive capacity; • partial and total lead time; • Percentage of saturation, Value Added (VA) and Non-Value Added (NVA), for each worker and station. During the development phase, an important goal has been pursued: the possibility to use and change the model without knowing the creation logic. It is possible to change input parameters through simple tables, which contain times of man-machine operations. You can easily set times in order to move an operation from one station to another or to add/delete a job in a station, according to the technological and ergonomic constraints of the process. Moreover, the acquisition of scheduling data is extremely easy and starts from the generation of a list of production codes related to different work-cycles. © 2010 Simulation Councils, Inc

Ventilation strategies to minimise the airborne virus transmission in indoor environments

A key challenge to fight the Covid-19 pandemic is to minimise the airborne transmission of the SARS-CoV-2 virus. Highly crowded indoor environments, such as schools, become possible hotspots for virus spreading because the basic non-pharmaceutical mitigation measures applied until now are not effective in reducing the virus airborne transmission mode, which is the principal one in indoor environments and requires improved ventilation. In the present study, a mass balance equation was applied to typical school scenarios to evaluate (i) required air exchange rates for mechanically-ventilated classrooms and (ii) adequate airing procedures for naturally ventilated classrooms. In the case of naturally ventilated classrooms, a feedback control strategy was evaluated using the measurements of indoor CO2. Our results show how these procedures can be applied in real life to support continued in-person instruction during a pandemic

Ultrafine particle emission from floor cleaning products

The new particle formation due to the use of cleaning products containing volatile organic compounds (VOCs) in indoor environments is well documented in the scientific literature. Indeed, the physical-chemical process occurring in particle nucleation due to VOC-ozone reactions was deepened as well as the effect of the main influencing parameters (ie, temperature, ozone). Nonetheless, proper quantification of the emission under actual meteo-climatic conditions and ozone concentrations is not available. To this end, in the present paper the emission factors of newly generated ultrafine particles due to the use of different floor cleaning products under actual temperature and relative humidity conditions and ozone concentrations typical of the summer periods were evaluated. Tests in a chamber and in an actual indoor environment were performed measuring continuously particle number concentrations and size distributions during cleaning activities. The tests revealed that a significant particle emission in the nucleation mode was present for half of the products under investigation with emission factors up to 1.1 × 1011 part./m2 (8.8 × 1010 part./mLproduct), then leading to an overall particle emission comparable to other well-known indoor sources when cleaning wide surfaces.</p