Analisys of just noticible difference in spectrum of church bell sound

Crkvena zvona su specifični muzički instrumenti kod kojih se zbog tehnike livenja tačnost spektralnih komponenti teško može realizovati s potpunom preciznošću. Zbog toga se postavlja pitanje subjektivne primetnosti nesavršenosti njegovog zvuka. U ovom radu prikazani su rezultati analize jedva primetnih razlika u spektralnoj strukturi zvuka crkvenih zvona. Izvršeni su subjektivni testovi sa sintetizovanim signalima zvuka dva crkvena zvona različitih veličina. Zaključeno je da su jedva primetne razlike odstupanja frekvencija spektralnih komponenti u intervalu 5-25 centi i da zavise od frekvencije.Bells are specific sound sources. They have distinct, but, unlike music instruments, inharmonious partials. These partials arise from modes of vibration of the bell and depend on dimensions and potential irregularities of the bell. Therefore, question of just noticible difference in the church bell sound is of great importance. Analisys of subjektive tests with sinthetic sounds of two bells, different in size, are described in this paper. We report results for just noticible difference of parcial frequency in range 10-15 cents. Frequency dipendance, also, noticed

Subjective identification of imperfection in curch bells sound – initial research

Cilj ovoga rada je bio da se utvrde granice devijacije frekvencija parcijala u zvuku crkvenih zvona pri kojima se konstatuje disharmoničnost njihovog zvuka. U tom cilju izvršeni su subjektivni testovi sa sintetisanim signalima koji su reprezentovali zvuke crkvenih zvona čija je masa reda veličine 50 kg i 250 kg. Konstatovano je da se disharmoničnost primećuje pri odstupanjima frekvencije parcijala koja su u intervalu 10-20 centi, zavisno od frekvencije.Bells are very specific sound sources. They have distinct, but, unlike music instruments, inharmonious partials. These partials arise from modes of vibration of the bell and depend on dimensions and potential irregularities of the bell. Problems of analysis of such signal, including detecting partials and tracking their changes in time, and detecting potential irregularities, are descriebed in this paper

Poly(vinyl butyral)/nano-silver as a multifunctional coating for textile

This research considers a possibility to enhance the mechanical and spectrophotometric properties of a military camouflage cotton textile by applying a nano silver/poly(vinyl butyral), PVB, impregnation. Silver is known for its unique optical, electrical, thermal properties and antimicrobial activity[1]. PVB is chosen as a good impregnating matrix, being a thermoplastic elastomer with good adhesion behavior, resistant to wetting [2]. Impregnated fabric samples were examined regarding spectrophotometric properties and mechanical abrasion resistance. To achieve low visibility, besides being painted to match the colors of the environment, a surface must scatter light, so it should have a matte, low gloss coating [3, 4]. Diffuse reflectance and gloss are related, and from a spectral point of view, scattering properties are relevant for surface appearance [5]. Certain nanostructures may alter this feature

PVB/IF-WS2 system for impregnation of polyester knitwear

Different types of textile materials are being used for military purposes. Cotton fabrics are the most commonly used for army personnel protection. Therefore lots of different approaches have been developed for camouflage prints. On the other hand, different polymers are used as impregnation of fabrics for this reason, and nowadays, nanotechnologies play important role in enhancing the textile materials. In our previous study the possibility of camouflage textile impregnation has been examined, with a polymer and nanostructures that was earlier proven to be beneficial in aspects of decreasing friction and wear, increasing mechanical resistance and enhancing camouflage properties [1-3, 4, 5]. Polyvinyl butyral, PVB was chosen as impregnating polymer which does not dissolve in water, i.e. resistant to wetting. Fullerenelike nanoparticles of tungsten disulfide, IF-WS2, were used as a nanoreinforcement due to their mechanical resistance and solid lubricating behavior [3, 4].Also, in our earlier research, a positive effect on spectrophotometric characteristics of military camouflage paints was shown [5, 6]. As a base material, in this research polyester knitwear was used, intended for protective clothing and other items that need to be camouflaged

Polymeric Impregnation Influence on Diffuse Reflection as the Main Characteristic for Determination of Camouflage Protection Properties of Military Textiles

There are two important features that have a significance when the camouflage protection abilities are in question. First, dyeing of the material and everything related to process of dying and the influence of the material impregnation which is most commonly used to improve physical and mechanical properties of textile. In our initial research, we examined influence of textile impregnation on the value of diffuse reflection within visible and near-infrared region of the electromagnetic spectrum. Some questions arose and we continued that initial research. The aim of this paper is to try to give answers on those questions. In the experiment polyamide cloth samples dyed with specific camouflage dyes and impregnated with polyurethane (pu) and chlorosulfonated polyethylene (csm) were used. Spectral reflection measurements in the wavelength area from 400 nm to 1000 nm were performed for the light green, beige green, dark green, brown and black tone for impregnated as well as for non-impregnated samples. The measurements were conducted using the uv/vis/nir spectrophotometer uv 3600 from a japanese manufacturer shimadzu with an integrating sphere. The measurement uncertainty was 2% and the uv probe programme package was used. This first experiment showed that impregnation affects the value of diffuse reflection, therefore further tests have been conducted. Here, we present results of the scanning electron microscope (sem) analysis. Samples were analyzed using jeol jsm-6610 in lv (low vacuum) mode and a voltage of 15 kv was applied, for same types of samples and same shades. The results did not show great difference between samples. Regarding the values of diffuse reflection, however, we still need to find a way to explain obtained differences so further tests will be performed such as ftir or eds

Follow up of Cs-137 activity in the first 100 samples in the area of Kumodraz, Belgrade in the 2008 to 2011 period

This paper presents results of gamma spectrometric analyses of air samples, collected in the period from 2008 to 2011, at Kumodraz location. Cs-137 specific activity has been monitored for 4 years. Exposure rate of gamma background radiation has been showed, as well. Obtained results show that average annual effective doses are in the range from 1.01 to 1.19 mSv/y and lower than the worldwide average.I International Conference on Radiation in Various Fields of Research : RAD 2017 : proceedings book; April 25-27, 2012; Niš, Serbi

Effect of IF-WS2 nanoparticles addition on physical-mechanical and rheological properties and on chemical resistance of water-based paints

Transition-metal dichalogenides (MoS2 , WS2 , NbS2 , etc.), due to their excellent mechanical properties, are used for a wide range of applications, including aerospace and automotive technology, load bearing and release mechanisms, as solid lubricants, corrosion protection etc. In the form of inorganic fullerene-like particles, with unique morphology, spherical and closed structure, they possess a chemical inertness and a high elasticity. Due to these exceptional characteristics, inorganic fullerene-like particles, such as tungsten disulfide IF-WS2 , are recognized as promising materials and promising fillers of the composites and are extensively studied for their ability to control wetting, adhesion, lubrication on surfaces and interfaces, and to achieve good corrosion resistance. In this paper, a possibility is examined to improve properties of water-based paints by adding nanoparticles of IF-WS2 . Since they have low % VOC (volatile organic compound), water-based paints are eco-friendly substitute for common polymeric coatings, and nowadays it is very important to introduce their usage as much as possible. IF-WS2 were dispersed in paint by ultrasonic irradiation. Physical-mechanical properties and chemical resistance were examined. The following properties were compared for paint without and with IFWS2 nanoparticles: hardness, flexibility, elasticity, adhesion, abrasion resistance, IR reflection. Also, resistance to salt atmosphere and salt water were compared. The effect of adding IF-WS2 on rheological properties of the paints has been examined using Dynamic Mechanical Analysis (DMA), observing viscosity as the function of the shear rate

Follow up of Cs-137 activity in the first 100 samples in the area of Kumodraz, Belgrade in the 2008 to 2011 period

This paper presents results of gamma spectrometric analyses of air samples, collected in the period from 2009 to 2011, at Kumodraz location. Cs-137 specific activity has been monitored for 4 years. Exposure rate of gamma background radiation has been showed, as well. Obtained results show that average annual effective doses are in the range from 1.01 to 1.19 mSv/y and lower than the worldwide average.I International Conference on Radiation in Various Fields of Research : RAD 2017 : proceedings book; April 25-27, 2012; Niš, Serbi

Spectrophotometric and thermal properties of poly(vinyl butyral) and epoxy protective coatings with nanostructures of WS2

PVB is a flexible but tough polymer of excellent optical clarity and transparence, and due to that it has a wide application in different coatings and in laminated glass industry. Epoxy resin has good mechanical resistance and it is also applied in coatings, but also as a binder in composites. In this research a possibility was examined to improve thermal resistance and spectrophotometric properties of thin film coatings of PVB and epoxy modified with addition of 10 wt.% of PVB, by addition of small concentrations of tungsten disulfide nanotubes and nanoparticles. Coatings were applied on glass plates by solvent-casting technique: PVB and epoxy/PVB were dissolved in ethanol in which previously nanostructures were deagglomerated and dispersed using ultrasonic probe. Inorganic fullerene-like nanoparticles of tungsten disulphide (IF-WS2) were added in concentration 1 wt.% and nanotubes (INT-WS2) in concentration 0.3 wt.%. Dispersion of tungsten disulfide nanostructures was observed using scanning electron microscope. Thermal resistance was examined by differential scanning calorimetry. The following spectrophotometric properties were examined: diffuse reflection and transmition, using spectrophotometer Shimadzu UV 3600 with an integrating sphere and UV Probe programme package, and specular gloss, using glossmeter Elcometer 480, under angles 20°, 60° and 85°. Observed results have indicated that new composite coatings with nanostructures have enhanced thermal resistance and camouflage properties for potential military applications.Seventeenth Young Researchers' Conference Materials Sciences and Engineerin

Svojstva standardnog polimernog i vodorazredivog premaza za vojnu maskirnu zaštitu sa dodatkom neorganskih fulerenskih nanočestica volfram disulfida (IF-WS2)

The possibility of improving the properties of the standard polymeric and a water-based coating for military camouflage protection by adding nanoparticles of inorganic fulerene-like tungsten disulphide (IF-WS2). Nanoparticles were added and dispersed in paint by ultrasonic irradiation. The paints were applied to standard steel plates, and dried, for examinations of chemical resistance to aggressive media and of the following physical-mechanical properties: hardness, flexibility, elasticity, abrasion resistance, resistance to steel balls impact and adherence. These properties were compared for paint without and with IF-WS2 nanoparticles. The effect of adding IF-WS2 on rheological properties of the paints has been examined using Dynamic Mechanical Analysis (DMA), observing viscosity as a function of the shear rate. Camouflage properties were also examined - IR reflection and colorimetry. Significant improvements of mechanical resistance to abrasion and steel balls impact, as well as hardness, have been achieved.Istraživana je mogućnost poboljšanja svojstava standardnog polimernog i vodorazredivog premaza za vojnu maskirnu zaštitu dodatkom neorganskih fulerenskih nanočestica volfram-disulfida, IF-WS2. Nanočestice su dodate i u boji dispergovane ultrazvučno. Boje su nanešene na standardne čelične pločice, nakon toga osušene, u cilju ispitivanja hemijske otpornosti na agresivne medije i sledećih fizičko-mehaničkih karakteristika: tvrdoća, savitljivost, elastičnost, otpornost na abraziju, otpornost na udar kuglica i prianjanje. Ova svojstva su poređena za boje bez i sa dodatkom IF-WS2 nanočestica. Uticaj dodatka IF-WS2 na reološka svojstva ispitivanih boja praćen je pomoću Dinamičkog Mehaničkog Analizatora (DMA), posmatrajući promenu viskoziteta u funkciji od brzine smicanja. Takođe, ispitivane su i maskirne karakteristike- infracrvena refleksija i kolorimetrija. Postignuta su značajna poboljšanja tvrdoće, mehaničke otpornosti na udar čeličnih kuglica i abraziju