Autor: Silva, P. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Sound, Noise and Speech at the 9000-Seat Holy Trinity Church in Fatima, Portugal
Autorzy:: Carvalho, A. P. O.
Silva, P. M. A.
Tematy:: church
acoustics
Rapid Speech Transmission Index (RASTI)
reverberation time; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/177982.pdf Link otwiera się w nowym oknie
Opis:: This paper presents the interior acoustical characterization of the 9,000-seat church of the Holy Trinity in the Sanctuary of Fátima, Portugal, inaugurated in 2007. In situ measurements were held regarding interior sound pressure levels (with and without the HVAC equipment working), NC curves, RASTI (with and without the installed sound system) and reverberation time. The results are presented and commented according to the design values. A comparison is made with other churches in the world, also with a very large volume (for instance the Basilica Mariacka in Gdansk). The measured data are also used to calculate a global index of this church acoustic quality using Engel’s and Kosała's Index Method.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Research on the Portuguese building stock and its impacts on energy consumption – an average U-value approach
Autorzy:: Sousa, J.
Bragança, L.
Almeida, M.
Silva, P.
Tematy:: zasoby budynków
zasoby energii
zużycie energii
element konstrukcyjny
przenikanie ciepła
współczynnik przenikania ciepła
building stock
energy resources
energy consumption
structural element
heat transfer
heat transfer coefficient; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/231236.pdf Link otwiera się w nowym oknie
Opis:: The article aims to evaluate the Portuguese building stock energy policies and strategy for energy saving in buildings among the EU members. It was found out the average heat transfer coefficients of the main structural elements of Portuguese Buildings and analyzed the U-values of this elements considering different time periods. The fundamentals of this study were funded by the Agency for Development and Innovation (ADI) and co-financed by the European Regional Development Fund (FEDER) through the Operational Program for Competitiveness Factors (POFC) assigned to the Building Physics and Construction Technology Laboratory with the reference SB Tool SPT_2011_4.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Development of environmentally-friendly technologies based on the Double-ECO model – an evaluation platform
Autorzy:: Pena-Gonzalez, L. E.
Da Silva, P.
Tanabe, I.
Tematy:: eco-efficiency
lubrication
life cycle assessment (LCA)
Mahalanobis-Taguchi system; Pokaż więcej
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Powiązania:: https://bibliotekanauki.pl/articles/100204.pdf Link otwiera się w nowym oknie
Opis:: In recent years, the urgency to create environmentally-friendly technologies has dramatically increased. However, these technologies are usually not adopted due to their large cost and low profit. Previously the “Double-ECO model” has been proposed as a methodology that reconciles both “Economy” and “Ecology”, which relies on the exploration of technology alternatives that offer an improved mechanical performance. Here, as mechanical performance, cost and environmental impact were meant to be approached under the same degree of priority, this model was thought to offer the basis for a broader technology development framework. The current research initiates said framework by proposing an evaluation platform, which through a transition from a focus on environmental-friendliness towards an improved eco-efficiency definition lays groundwork for an automated evaluation. This was done by defining a dimensionless evaluation parameter based on existing methodologies and referred as the “DE Index”. This paper applied the proposed evaluation method into a machine tool lubrication technology example. It was concluded that, (1) the platform was able to effectively compare technologies under the proposed eco-efficiency parameter, (2) the developed technology possessed improvements in the environmental pollution output, mechanical performance and cost when compared to conventional technologies.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Machine tool distortion estimation due to environmental thermal fluctuations – a focus on heat transfer coefficient
Autorzy:: Da Silva, P.
Pena-Gonzalez, L. E.
Tanabe, I.
Takahashi, S.
Tematy:: environmental thermal fluctuations
thermal deformation
machine tool
heat transfer coefficient; Pokaż więcej
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Powiązania:: https://bibliotekanauki.pl/articles/99879.pdf Link otwiera się w nowym oknie
Opis:: Thermally induced errors have been approached in multiple ways due to the influence these have over the positional accuracy of a machine tool. Here, approaches regarding environmental thermal fluctuations surrounding a machine tool remain to be explored in detail. These fluctuations have been explored in terms of the heat transfer coefficient and thermal radiation of the machine shop walls, as well as in terms of seasonality and varying thermal gradients. This paper presents additional considerations regarding environmental temperature perturbations, as heat transfer coefficient fluctuations in the machine shop were thought to play a significant role in machine tool thermal deformation a broader term for these phenomena, environmental thermal fluctuations, was defined and evaluated. Specifically, an environmental thermal data survey of a machine shop was explored. This data was then applied to a NC milling machine and a CNC jig borer FEM analyses and compared to experimental data. FEM simulations were then used to demonstrate that convection regimes and heat transfer coefficient values at a machine shop have a significant influence over machining precision. Here, under maximum and minimum heat transfer coefficient values, the NC milling machine and CNC jig borer simulations results showed an error of cut difference up to 36.5 μm and 18.17 μm, respectively. In addition, as the importance of the heat transfer coefficient was highlighted, considerations regarding machine tool surface color were deemed relevant and were described.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: The analysis of environmental and human impacts of using Strong Alkaline Water for cooling during machining
Autorzy:: Da Silva, P.
Tanabe, I.
Junior, D. C. R.
Takahashi, S.
Tematy:: eco-friendly
strong alkaline water
emission
cooling; Pokaż więcej
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Powiązania:: https://bibliotekanauki.pl/articles/99481.pdf Link otwiera się w nowym oknie
Opis:: An eco-friendly manufacturing approach is important for the environment. Enhancing machining performances is not only required to improve product’s quality, time saving, and reduces costs; it is also contributed to the environmental protection efforts. Cooling is important aspect for obtaining this purpose. Therefore the benefits of Strong Alkaline Water (SAW) cooling method was assessed and compared with conventional wet cutting method. An experiment was performed at Nagaoka University of Technology machining centre. Three machine tools including a milling machine, a drilling machine and a turning machine were used. The study shows that using SAW for cooling is far more efficient than conventional cooling method. It reduces annual global warming potential by 72.95%, acidification potential 98.18%, ozone depletion potential 99.6%, smog formation potential 85.71% and human toxicity potential 42.86% compare with conventional method. The study concludes that besides inhibiting corrosion, prolonging tool life, improving surface roughness of final cutting and reducing energy usage, strong alkaline water cooling is an environmentally friendly approach and has positive impact on human health.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Effects of Process Related Variations on Defect Formation in Investment Cast Components
Autorzy:: Raza, M.
Silva, P.
Irwin, M.
Fagerström, B.
Jarfors, A. E. W.
Tematy:: thin-walled castings
casting defects
process variations
foundry practice
investment casting
odlewy cienkościenne
wady odlewu
zmiany procesu; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/380022.pdf Link otwiera się w nowym oknie
Opis:: Castability of thin-walled castings is sensitive to variation in casting parameters. The variation in casting parameters can lead to undesired casting conditions which result in defect formation. Variation in rejection rate due to casting defect from one batch to other is common problem in foundries and the cause of this variation usually remain unknown due to complexity of the process. In this work, variation in casting parameters resulting from human involvement in the process is investigated. Casting practices of different groups of casting operators were evaluated and resulting variations in casting parameters were discussed. The effect of these variations was evaluated by comparing the rejection statistics for each group. In order to minimize process variation, optimized casting practices were implemented by developing specific process instructions for the operators. The significance of variation in casting parameters in terms of their impact on foundry rejections was evaluated by comparing the number of rejected components before and after implementation of optimized casting practices. It was concluded that variation in casting parameters due to variation in casting practices of different groups has significant impact on casting quality. Variation in mould temperature, melt temperature and pouring rate due to variation in handling time and practice resulted in varying quality of component from one batch to other. By implementing the optimized casting instruction, both quality and process reliability were improved significantly.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Linear-wavelet networks
Autorzy:: Galvao, R. K. H.
Becerra, V. M.
Calado, J. M. F.
Silva, P. M.
Tematy:: sieć falkowa
model nieliniowy
analiza regresji
identyfikacja systemu
wavelet networks
nonlinear models
regression analysis
system identification; Pokaż więcej
Wydawca:: Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:: https://bibliotekanauki.pl/articles/907399.pdf Link otwiera się w nowym oknie
Opis:: This paper proposes a nonlinear regression structure comprising a wavelet network and a linear term. The introduction of the linear term is aimed at providing a more parsimonious interpolation in high-dimensional spaces when the modelling samples are sparse. A constructive procedure for building such structures, termed linear-wavelet networks, is described. For illustration, the proposed procedure is employed in the framework of dynamic system identification. In an example involving a simulated fermentation process, it is shown that a linear-wavelet network yields a smaller approximation error when compared with a wavelet network with the same number of regressors. The proposed technique is also applied to the identification of a pressure plant from experimental data. In this case, the results show that the introduction of wavelets considerably improves the prediction ability of a linear model. Standard errors on the estimated model coefficients are also calculated to assess the numerical conditioning of the identification process.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: A simulation strategy to determine the mechanical behaviour of cork-rubber composite pads for vibration isolation
Autorzy:: Lopes, Helena
Silva, Susana P.
Machado, José
Tematy:: cork-rubber composites
compression
vibration isolation
linear regression
finite element analysis; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Powiązania:: https://bibliotekanauki.pl/articles/2057983.pdf Link otwiera się w nowym oknie
Opis:: The present work aimed to determine the performance of new cork-rubber composites, applying a modelling-based approach. The static and dynamic behaviour under compression of new composite isolation pads was determined using mathematical techniques. Linear regression was used to estimate apparent compression modulus and dynamic stiffness coefficient of compounds samples based on the effect of fillers, cork and other ingredients. Using the results obtained by regression models, finite element analysis (FEA) was applied to determine the behaviour of the same cork-rubber material but considering samples with different dimensions. The majority of the regression models presented R2 values above 90%. Also, a good agreement was found between the results obtained by the presented approach and previous experimental tests. Based on the developed methodology, the compression behaviour of new cork-rubber compounds can be accessed, improving product development stages.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Corrosion Behavior of FeAl and Fe3Al Based Fe-Al-C Alloys in Sulfuric Acid
Autorzy:: Silva, A. P.
Brito, P. P.
Martins, N.
Tematy:: iron aluminides
microstructure
mechanical properties
corrosion resistance; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/2134209.pdf Link otwiera się w nowym oknie
Opis:: Iron aluminides are iron-aluminum alloys that have excellent resistance to oxidation at high temperatures with low density, high resistance/weight ratio and a low manufacturing cost. Due to its characteristics, these alloys are presented as an option to replace stainless steels in certain applications. This works intends report the casting process and subsequent analyses involving microstructure, mechanical properties, and corrosion resistance of two Fe-Al-C alloys (Fe-11wt%Al and Fe-25wt%Al, containing 0.31-0.37%C), which were prepared in an induction furnace and poured in a permanent mold. Samples of these alloys were characterized and presented elevated hardness values of 37 HRC (alloy Fe-11wt%Al) and 49.6HRC (alloy Fe-25wt%Al) and microstructure with aluminides type Fe3Al and FeAl and also carbides type K. The Fe-11wt%Al alloy exhibited superior resistance to uniform corrosion, although both Fe-Al-C alloys exhibited significantly higher corrosion rates compared to a binary iron aluminide in 0.5M H2SO4 containing naturally dissolved oxygen.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Using a segmented voltage sweep mode and a Gaussien curve fitting method to improve heavy metal measurement system performance
Autorzy:: Dias Pereira, J. M.
Postolache, O.
Silva Girao, P.
Tematy:: heavy metals measurement
electrochemical analysis
voltammetry
auto-calibration and curve fitting; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/220629.pdf Link otwiera się w nowym oknie
Opis:: This paper presents a voltammetric segmented voltage sweep mode that can be used to identify and measure heavy metals' concentrations. The proposed sweep mode covers a set of voltage ranges that are centered around the redox potentials of the metals that are under analysis. The heavy metal measurement system can take advantage of the historical database of measurements to identify the metals with higher concentrations in a given geographical area, and perform a segmented sweep around predefined voltage ranges or, alternatively, the system can perform a fast linear voltage sweep to identify the voltammetric current peaks and then perform a segmented voltage sweep around the set of voltages that are associated with the voltammetric current peaks. The paper also includes the presentation of two auto-calibration modes that can be used to improve system's reliability and proposes the usage of a Gaussian curve fitting of voltammetric data to identify heavy metals and to evaluate their concentrations. Several simulation and experimental results, that validate the theoretical expectations, are also presented in the paper.
Dostawca treści:: Biblioteka Nauki

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