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Tytuł:
Study of the Acoustic Suitability of an Open Plan Office Based on STI and DL2 Simulations
Autorzy:
Passero, C. R. M.
Zannin, P. H. T.
Powiązania:
https://bibliotekanauki.pl/articles/178137.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
open plan offices
acoustic evaluation
acoustic improvement
Opis:
Many business offices around the world are organized as open plan offices. Therefore, studies about the acoustic comfort of the people who work in them have become increasingly important. The focus of this work is the acoustic evaluation of an open plan office combining several architectural characteristics and levels of ambient noise. This evaluation was performed through a computational model calibrated from a real office. The rate of spatial decay of sound pressure levels per distance doubling (DL2) and the speech transmission index (STI) were simulated for the acoustic evaluation of the office, allowing for the determination of the radius of distraction (rD). These parameters were simulated for 6 situations using different floor and ceiling covering materials and inserting or withdrawing screens between workstations. In addition, STI and rD were simulated under two conditions of ambient noise. The results indicated that the DL2 and rD are adequate acoustic parameters for the acoustic evaluation and improvement of an open plan office. The DL2 was strongly influenced by the presence or absence of screens between workstations and by the ceiling covering material. The rD was more sensitive to changes in ambient noise.
Źródło:
Archives of Acoustics; 2012, 37, 2; 237-243
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Acoustic Emission Signals and Damage Analysis During the Tensile Test on Al8011 Hybrid Composites by Stir Casting Method
Autorzy:
Kannan, C. R.
Suresh, S.
Navaneetha Krishnan, M.
Powiązania:
https://bibliotekanauki.pl/articles/2203742.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al8011
stir casting
acoustic emission
tensile
corrosion
Opis:
Metal network compounds have primary properties. The use of lightweight and low vitality is a testament to the growing interest in the automotive industry. Aluminum alloys, due to their advanced physical, mechanical and tribological properties, have become a highly emerging material for a variety of industrial applications and the importance of efficient material selection is explained. In this paper, an Al8011 hybrid metal matrix composite is developed through the stir casting process. The different weight proportions of B4C (3%, 6%, 9% & 12%) and fixed proportions of 2% MoS2 have been used. Composite developed are subjected to mechanical properties evaluation and seawater corrosion studies following standard procedures. To study the porosity of the composite samples, theoretical density and actual density are calculated. An acoustic emission system-assisted tensile test is carried out to report the strength of the composite. From this experimental method, adding reinforcement can increase the tensile strength and hardness of the composites. Under sea water, the increase in reinforcement found an increase in corrosion resistance. Fractured surfaces were perused using SEM and EDS analysis.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 1; 223--235
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical Spectroscopy of MgB2 Containing SiC
Spektroskopia mechaniczna MgB2 zawierającego SiC
Autorzy:
Silva, M. R.
Silva, L. B. S.
Rodriques Jr., D.
Grandini, C. R.
Powiązania:
https://bibliotekanauki.pl/articles/355880.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mechanical spectroscopy
internal friction
anelasticity
MgB2
SiC
spektroskopia mechaniczna
tarcie wewnętrzne
właściwości anelastyczne
Opis:
The compound magnesium diboride (MgB2) has been well-known since the 1950s; however, its superconducting properties were unknown. Intrinsic characteristics of MgB2 make this material a promising candidate for technological applications, although the low value of the irreversibility field and the decrease in critical current density with the increase in the magnetic field considerably reduce its utility. The present work aimed to study the effect of carbon-based doping on anelastic properties of MgB2 as measured by mechanical spectroscopy. The samples were prepared by using the powder-intube method. The samples were made with 5, 7.5, and 10 wt.% of silicon carbide (SiC). The results reveal complex mechanical loss spectra caused by the interaction between point defects and surface defects in the crystalline lattice of MgB2.
Dwuborek związek magnezu (MgBV) jest znany od 1950 roku; jednak jego właściwości nadprzewodzące były nieznane. Swoiste cechy MgB2 czynią ten materiał obiecującym kandydatem do zastosowań technicznych, jednak niskie wartości nieodwracalnego pola i zmniejszenie krytycznej gęstości prądu ze wzrostem pola magnetycznego znacznie zmniejszają jego użyteczność. Celem pracy było zbadanie wpływu domieszkowania związkiem węgla na anelastyczne właściwości MgB2 mierzone metodą spektroskopii mechanicznej. Próbki zostały przygotowane za pomocą metody powder-in-tube (PIT). Wytworzono próbki o zawartości 5, 7.5 i 10 % wag. węglika krzemu (SiC). Wyniki pokazują złożone widma strat mechanicznych powodowanych przez wzajemne oddziaływanie pomiędzy defektami punktowymi i defektami powierzchniowymi w sieci krystalicznej MgB2.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 4; 3083-3086
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Internal Friction and Microstructure of Ti and Ti-Mo Alloys Containing Oxygen
Autorzy:
Martins Jr, J. R. S.
Araújo, R. O.
Nogueira, R. A.
Grandini, C. R.
Powiązania:
https://bibliotekanauki.pl/articles/351840.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mechanical spectroscopy
anelasticity
internal friction
Ti-Mo alloys
interstitials
biomaterials
Opis:
Ti-Mo alloys are promising materials for use as biomaterials, because these alloys have excellent corrosion resistance and a good combination of mechanical properties such as fatigue, low elastic modulus, hardness, and wear resistance. The objective of this paper was to study the effect of heavy interstitial atoms on anelastic properties of Ti-Mo alloys using mechanical spectroscopy. The internal friction and Young’s modulus were measured as a function of temperature using dynamic mechanical analyser. The internal friction spectra were brought about by relaxation processes attributed to shortrange stress induced reorientation of interstitial and substitutional complexes in solid solution. It is suggested that the nature of the relaxing entities can be worked out in further research on Ti-Mo single crystals.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 1; 25-30
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cosmic Airburst on Developing Allerød Substrates (Soils) in the Western Alps, Mt. Viso Area
Autorzy:
Mahaney, William C.
West, Allen
Milan, Alison
Krinsley, David H.
Somelar, Peeter
Schwartz, Stephane
Milner, Michael W.
Allen, Christopher C.R.
Powiązania:
https://bibliotekanauki.pl/articles/2025231.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Black Mat impact/airburst
Reconstructed soil at time of YDB
mid-LG-YD paleosol Sedimentary products of cosmic impact/glacial recession
Nauki o Ziemi
Opis:
Although much has been written about a cosmic impact event in the Western Alps of the Mt. Viso area, the event closely tied with the Younger Dryas Boundary (YDB) of 12.8 ka and onset of the Younger Dryas (YD), the affected land surface is considered to contain a similar black mat suite of sediment found on three continents. While work elsewhere has focused on recovered sediment from lake and ice cores, buried lacustrine/alluvial records, and surface glacial and paraglacial records, no one has traced a mountain morphosequence of deposits with the objective of investigating initial weathering/ soil morphogenesis that occurred in ice recessional deposits up to the YDB when the surface was subjected to intense heat, presumably, as hypothesized by Mahaney et al. (2016a) from a cosmic airburst. With the land surface rapidly free of ice following glacial retreat during the Bølling-Allerød interstadial, weathering processes ~13.5 to 12.8 ka led to weathering and soil morphogenesis in a slow progression as the land surface became free of ice. To determine the exposed land character in the mid- to late-Allerød, it is possible to utilize an inverted stratigraphic soil morphogenesis working backward in time, from known post-Little Ice Age (LIA) (i.e. time-zero) through LIA (~0.45 to ~0.10 ka), to at least the middle Neoglacial (~2 ka), to answer several questions. What were the likely soil profile states in existence at the end of the Allerød just prior to the cosmic impact/airburst (YDB)? Assuming these immature weathered regolith sections of the Late Allerød approximated the <1 ka old profiles seen today, and assuming the land surface was subjected to a hypothesized instant temperature burst from ambient to ~2200oC at ~12.8 ka, what would be the expected effect on the resident sediment? To test the mid-LG (YDB) to YD relationship we analyzed the paleosols in both suites of deposits – mid-LG to YD – to test that the airburst grains are restricted to Late Allerød paleosols and using relative-age-determination criteria, that the overlapping YD to mid-LG moraines are closely related in time. These are some of the questions about the black mat that we seek to answer with reference to sites in the upper Guil and Po rivers of the Mt. Viso area.
Źródło:
Studia Quaternaria; 2018, 35; 3-23
1641-5558
2300-0384
Pojawia się w:
Studia Quaternaria
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Climate change research - what do we need really?
Autorzy:
Prasad, P.R.C.
Powiązania:
https://bibliotekanauki.pl/articles/12022.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
This research note focuses on the current climate change research scenario and discusses primarily what is required in the present global climate change conditions. Most of the climate change research and models predict adverse future conditions that have to be faced by humanity, with less emphasis on mitigation measures. Moreover, research ends as reports on the shelves of scientists and researchers and as publications in journals. At this juncture the major focus should be on research that helps in reducing the impact rather than on analysing future scenarios of climate change using different models. The article raises several questions and suggestions regards climate change research and lays emphasis on what we really need from climate change researchers.
Źródło:
Papers on Global Change; 2015, 22
2300-8121
1730-802X
Pojawia się w:
Papers on Global Change
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hybrid Reduced Model of Rotor
Hybrydowy zredukowany model wirnika
Autorzy:
Hein, R.
Orlikowski, C.
Powiązania:
https://bibliotekanauki.pl/articles/139510.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mechanical system
modelling
vibration
system mechaniczny
modelowanie
wibracja
Opis:
In the paper, the authors describe the method of reduction of a model of rotor system. The proposed approach makes it possible to obtain a low order model including e.g. non-proportional damping or the gyroscopic effect. This method is illustrated using an example of a rotor system. First, a model of the system is built without gyroscopic and damping effects by using the rigid finite element method. Next, this model is reduced. Finally, two identical, low order, reduced models in two perpendicular planes are coupled together by means of gyroscopic and damping interaction to form one model of the system. Thus a hybrid model is obtained. The advantage of the presented method is that the number of gyroscopic and damping interactions does not affect the model range.
W pracy zaprezentowano metodę redukcji modelu wirnika z efektem żyroskopowym i tłumieniem. Do budowy modelu zredukowanego wykorzystano dwie metody konstruowania przybliżonych modeli dyskretnych układów ciągłych - metodę dekompozycji modalnej oraz metodę dyskretyzacji przestrzennej (elementów skończonych). Zredukowany model modalny zbudowano dla tej części modelu, dla której łatwo jest formułować warunki ortogonalności. Pozostałe zjawiska, które powodują trudności w formułowaniu warunków ortogonalności np. efekt żyroskopowy lub nieproporcjonalne tłumienie, zamodelowano z wykorzystaniem metody elementów skończonych. Następnie powiązano ze sobą dwa takie same modele drgające w płaszczyznach wzajemnie prostopadłych poprzez zamodelowane oddziaływania żyroskopowe lub nieproporcjonalne tłumienie. Zaprezentowana metoda umożliwia otrzymanie modelu wirnika niskiego rzędu przy zmiennej prędkości kątowej oraz z dowolnym rodzajem tłumienia wewnętrznego i zewnętrznego. Zaprezentowany przykład analizy wirnika potwierdza skuteczność zaproponowanego ujęcia.
Źródło:
Archive of Mechanical Engineering; 2013, LX, 3; 319-333
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vibrations of railroad due to the passage of the underground train
Drgania toru wywołane przejazdem kolei podziemnej
Autorzy:
Konowrocki, R.
Bajer, C.
Powiązania:
https://bibliotekanauki.pl/articles/224210.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
drgania toru
kolej podziemna
tunel warszawskiego metra
tarcie
poślizg
dynamic train-track interaction
ground borne vibrations
curved and straight track
underground train
Opis:
In the paper we present results of vibration measurements in the train and on the base of the railroad in tunnels of Warsaw Underground. Measurements were performed at straight and curved sections of the track. The paper is focused on the influence of the lateral slip in rail/wheel contact zone on the generation of vibrations and a noise. Vibrations were analyzed in terms of accelerations, velocities or displacements as a function of time and frequency. Results ware compared with the experiment of rolling of the wheel with lateral sleep. In both cases we observed double periodic oscillations.
W pracy zajęto się zagadnieniem dynamicznego oddziaływania pojazdu szynowego na tor w tunelu warszawskiego metra. Skupiono się w niej głównie na zagadnieniu kontaktu tocznego z uwzględnieniem tarcia bocznego i poślizgów bocznych. Na podstawie pomiarów eksperymentalnych zarejestrowanych w kolei podziemnej oraz na stanowisku laboratoryjnym wykazano istnienie drgań dwuokresowych, wywoływanych poślizgiem bocznym. Wykorzystując model matematyczny, opisany układem fizycznym o dwóch stopniach swobody, uzyskano odpowiedź dynamiczną o charakterze zbliżonym do zachowania się układu eksperymentalnego. Zamieszczone w pracy wyniki analiz mogą zainteresować badaczy zajmujących się transportem szynowym, kontaktem tocznym i zużyciem materiałów.
Źródło:
Archives of Transport; 2010, 22, 1; 61-82
0866-9546
2300-8830
Pojawia się w:
Archives of Transport
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of a Committee of Artificial Neural Networks for the Performance Testing of Compressors for Thermal Machines in Very Reduced Times
Autorzy:
Coral, R.
Flesch, C. A.
Penz, C. A.
Borges, M. R.
Powiązania:
https://bibliotekanauki.pl/articles/221092.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
refrigeration compressor
artificial neural networks
performance test
Opis:
This paper presents a new test method able to infer - in periods of less than 7 seconds - the refrigeration capacity of a compressor used in thermal machines, which represents a time reduction of approximately 99.95% related to the standardized traditional methods. The method was developed aiming at its application on compressor manufacture lines and on 100% of the units produced. Artificial neural networks (ANNs) were used to establish a model able to infer the refrigeration capacity based on the data collected directly on the production line. The proposed method does not make use of refrigeration systems and also does not require using the compressor oil.
Źródło:
Metrology and Measurement Systems; 2015, 22, 1; 79-88
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rayleigh-Bénard convection in an elastico-viscous Walters’ (model B’) nanofluid layer
Autorzy:
Rana, G. C.
Chand, R.
Powiązania:
https://bibliotekanauki.pl/articles/202036.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nanofluid
oscillatory convection
Rayleigh-Benard convection
viscoelasticity
Walters' (model B') fluid
oscylacyjna konwekcyjna
komórki Bénarda
lepkosprężystość
Opis:
In this study, the onset of convection in an elastico-viscous Walters’ (model B’) nanofluid horizontal layer heated from below is considered. The Walters’ (model B’) fluid model is employed to describe the rheological behavior of the nanofluid. By applying the linear stability theory and a normal mode analysis method, the dispersion relation has been derived. For the case of stationary convection, it is observed that the Walters’ (model B’) elastico-viscous nanofluid behaves like an ordinary Newtonian nanofluid. The effects of the various physical parameters of the system, namely, the concentration Rayleigh number, Prandtl number, capacity ratio, Lewis number and kinematics visco-elasticity coefficient on the stability of the system has been numerically investigated. In addition, sufficient conditions for the non-existence of oscillatory convection are also derived.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2015, 63, 1; 235-244
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Key-point Detection based Fast CU Decision for HEVC Intra Encoding
Autorzy:
Xu, Z.
Min, B.
Cheung, R. C. C.
Powiązania:
https://bibliotekanauki.pl/articles/226128.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
HEVC
video coding
fast CU decision
corner detection
Opis:
As the most recent video coding standard, High Efficiency Video Coding (HEVC) adopts various novel techniques, including a quad-tree based coding unit (CU) structure and additional angular modes used for intra encoding. These new techniques achieve a notable improvement in coding efficiency at the penalty of significant computational complexity increase. Thus, a fast HEVC coding algorithm is highly desirable. In this paper, we propose a fast intra CU decision algorithm for HEVC to reduce the coding complexity, mainly based on a key-point detection. A CU block is considered to have multiple gradients and is early split if corner points are detected inside the block. On the other hand, a CU block without corner points is treated to be terminated when its RD cost is also small according to statistics of the previous frames. The proposed fast algorithm achieves over 62% encoding time reduction with 3.66%, 2.82%, and 2.53% BD-Rate loss for Y, U, and V components, averagely. The experimental results show that the proposed method is efficient to fast decide CU size in HEVC intra coding, even though only static parameters are applied to all test sequences.
Źródło:
International Journal of Electronics and Telecommunications; 2018, 64, 3; 321-327
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A description of the sources of magnetic field using edge values of the current vector potential
Autorzy:
Wojciechowski, R. M.
Jędryczka, C.
Powiązania:
https://bibliotekanauki.pl/articles/140898.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
numerical modeling
edge element analysis
current vector potential T0
stranded windings
Opis:
The paper discusses the method of a description of the magnetic field sources in systems with the stranded windings. The sources are determined on the basis of an obtained distribution of edge values of the current vector potential T0. The formulas describing the magnetic field sources in the finite element (FE) space for the formulations using the scalar potential F and the vector potential A have been given. The approach for determining the T0 distribution in the stranded windings of simple and complex geometries has been proposed.
Źródło:
Archives of Electrical Engineering; 2018, 67, 1; 17-26
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modular transportation system with a three dimensional routeing
Autorzy:
Löffler, C.
Canders, W. R.
Powiązania:
https://bibliotekanauki.pl/articles/141161.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
3D-Linear Motor
passive switch
Steep turn
logistic
modular transportation system
Opis:
In intra-enterprise logistics and automation of manufacturing processes general a rising productivity by high flexibility is required. Existing transportation systems exclusively use two-dimensional track sections, because they can be served with standard drives. Because of these simple structures the transport speed is limited and thereby also the throughput. In this paper now a modular transportation system is presented which could reach higher speeds with a direct drive and the use of centrifugal force compensating curves. Simultaneously the system also can change the altitude. All this succeeds with the integration of three-dimensional track sections. Therefore a two piped guiding system with a long stator linear motor was designed. To combine the linear motor with the three dimensional track special stator elements were developed which allow a bending of the stator to follow the route course. The current work deals with the implementation of a mechanical passive switch, which is operated by the electromagnetic forces of the linear motor. So no additional mechanical actors or a separate electromagnetic system are necessary.
Źródło:
Archives of Electrical Engineering; 2015, 64, 4; 641-654
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Carpooling Scheme Selection for Taxi Carpooling Passengers: a Multi-Objective Model and Optimisation Algorithm
Autorzy:
Xiao, Q.
He, R.-C.
Powiązania:
https://bibliotekanauki.pl/articles/223987.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
traffic engineering
taxi carpooling
multi-objective optimisation
information entropy
inżynieria ruchu
system carpooling
wspólne dojazdy
infrastruktura transportowa
optymalizacja
Opis:
Carpooling has been long deemed a promising approach to better utilizing existing transportation infrastructure, the carpooling system can alleviate the problems of traffic congestion and environmental pollution effectively in big cities. However, algorithmic and technical barriers inhibit the development of taxi carpooling, and it is still not the preferred mode of commute. In order to improve carpooling efficiency in urban, a taxi carpooling scheme based on multi-objective model and optimisation algorithm is presented. In this paper, urban traffic road network nodes were constructed from the perspective of passenger carpooling. A multi-objective taxi carpooling scheme selection model was built based on an analysis of the main influences of carpooling schemes on passengers. This model aimed to minimise get-on-and-get-off distance, carpooling waiting time and arriving at the destination. Furthermore, a two-phase algorithm was used to solve this model. A rapid searching algorithm for feasible routes was established, and the weight vector was assigned by introducing information entropy to obtain satisfying routes. The algorithm is applied to the urban road, the Simulation experimental result indicates that the optimisation method presented in this study is effective in taxi carpooling passengers.
Źródło:
Archives of Transport; 2017, 42, 2; 85-92
0866-9546
2300-8830
Pojawia się w:
Archives of Transport
Dostawca treści:
Biblioteka Nauki
Artykuł

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