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New worldwide trends such as globalization have rendered grinding processes increasingly important for industry, making it essential to perform in-depth studies of variations in grinding process parameters in the pursuit of greater cost effectiveness. This paper presents a comparative analysis of three different infeed rates, using a conventional grinding wheel on quenched and tempered D2 steel workpieces. Higher infeed rates are known to be correlated with shorter grinding times, rendering the process more economically attractive. Two different coolant fluids, 5% emulsion and pure oil, were used. The tests were carried out using the smallest possible amount of coolant and an optimized 5 mm diameter nozzle. The parameters analyzed were tangential force, specific energy, acoustic emission, roundness error and surface roughness. The surfaces of the workpieces were also examined by scanning electron microscopy (SEM). The results revealed that increased infeed rates could reduce processing times without compromising the quality of the workpiece profile, thereby reducing the cost of the process. The best cutting fluid, albeit more harmful to human health and less environmentally friendly, was found to be pure oil.

It is a well-discussed topic that Construction and Demolition Waste (CDW) can be recycled and used as aggregate in the construction sector. Generally, Brazilian construction techniques are based on hollow blocks or bricks and mortars as coating systems. This paper describes the sound insulation of a masonry wall built with hollow concrete blocks and CDW as aggregates. The measurements were performed according to the reverberant chamber method. Keeping sustainability in mind instead of applying cement mortar as coating system, Oriented Strand Boards (OSB) and Wood-Wool Cement Boards (WWCB) were used and also tested as acoustical linings. The panels were directly attached on the wall with nails in the receiving room. All types of panels increased the weighted sound reduction index ( R W ). Wood-based composites can also improve the air quality because of their hygroscopic properties. In summary, sustainable wall systems were characterized according to their sound insulation properties, presented as possible substitutes for traditional masonry walls. [ABSTRACT FROM AUTHOR]

• Nailing wood-based panels on the existing walls is an option for acoustic treatments. • WWCB improves intelligibility without absorbing excessive high-frequency energies. • A statistical sound absorption coefficient can be used at the mid-frequency range. The built environment might be acoustically treated in different ways in terms of complexity and cost. This research proposes an alternative for the acoustical treatment of an existing classroom through the insertion of wooden composites (i.e. panels) which were attached on the walls. This proposition sought to demonstrate an alternative that was easy in the context of implementation and feasible from the perspective of sustainability and cost. Industrialized wood composites from the south part of Brazil were chosen, such as the MDF (Medium Density Fiberboard), the OSB (Oriented Strand Board) and the WWCB (Wood-Wool Cement Board) with different thicknesses. In a acoustically treated classroom, the reverberation time ( T 20 ) and the Speech Transmission Index (STI) were evaluated as objective parameters. Three-dimensional models were built and validated with measurements using an open source software (I-SIMPA) in order to identify which scheme could provide the optimal T 20 . In order to complement the analysis, subjective tests were carried out with a sample of men and women to determine the Word Discrimination Testing (WDT) applied to the classroom environment. WWCB-type panels increased the STI values at different seats over the classroom and the analysis of the Sound Pressure Levels (SPL) distribution along the seats led to the conclusion that there was no excessive absorption of high-frequency energy. Finally, the subjective tests proved that the WWCB type (50.0 mm thick) improved the speech intelligibility. [ABSTRACT FROM AUTHOR]