Management of short wave unevenness of the rail head surface

Предмет истраживања у Дисертацији су неравнине малих таласних дужина на горњој површи главе шине у додиру са точком железничког возила. Циљ истраживања је развој методологије за управљање неравнинама малих таласних дужина (λ < 1 m) које настају услед контактног замора шинског челика (RCF). Управљање неравнинама на возној површи главе шине разматрано је у оквирима одрживог развоја железничке инфраструктуре, уз разматрање захтева корисника, железнице, привреде, животне средине, друштвене заједнице и безбедности транспорта. Разматрани су узроци појаве и механизам развоја неравнина, са посебним освртом на шинске дефекте који директно угрожавају безбедност железничког транспорта и негативно утичу на животну средину: head checking, squat, belgrospi и различити типови набораности површи главе шине. Разматране су смернице за развој стратегије управљања RCF дeфeктимa. Дат је преглед метода инспекције за рану детекцију поменутих дефеката. У Дисертацији је испитивана хипотеза да крутост шинске подлоге утиче на појаву и развој неравнина малих таласних дужина на возној површи главе шине. Представљени су резултати истраживања утицаја крутости елемената конструкције горњег и доњег строја на укупну крутост шинске подлоге, као и методе за утврђивање вертикалне крутости. Анализирана је неравномерна крутост шинске подлоге дуж колосека са аспекта конструкције и одржавања. Спроведено је експериментално истраживање утицаја крутости шинске подлоге на појаву и развој дефеката типа squat у станици Панчево Варош применом метода опште и детаљне визуелне инспекције колосека, као и методама електрометрије и сеизмометрије на изабраној мерној деоници. Резултати анализе мерних података указују на утицај променљиве крутости подлоге на појаву и развој squat дефеката. Предложене су смернице за даља истраживања.The subject of the research presented in the Dissertation is a short wave unevenness of the rail head surface in contact with the wheel of the railway vehicle. The research aim is developing a methodology for management of short wave unevenness (λ < 1 m) that occurs due to the contact fatigue of rail steel (RCF). The management of unevenness on the running surface of the rail head is considered within the framework of sustainable development of railway infrastructure, considering the requirements of users, railways, economy, environment, social community and transport safety. The causes of appearance and development mechanism of the unevenness were considered, with particular reference to rail defects that directly threaten the safety of railway transport and adversely affect the environment, such as head checking, squat, belgrospi and different types of surface corrugations of the rail head. Guidelines for the development of the management strategy of RCF defects were considered. An overview of inspection methods for early detection of the mentioned defects was presented. Dissertation investigated the hypothesis that the track stiffness influences the appearance and development of the short wave unevenness of the rail head surface. The research results of the influence of the railway superstructure and substructure on the track stiffness, as well as the methods for vertical stiffness measurement were presented. The uneven track stiffness along the track was analysed from the aspect of the structure and maintenance. An experimental investigation of the influence of track stiffness on the occurrence and development of squat defects in Pančevo Varoš railway station was performed using the methods of general and detailed visual inspection of tracks, as well as electrometric and seismic methods on the test section. The analysis of the obtained measurement data proved the influence of the uneven track stiffness on the occurrence and development of squat defects. Guidelines for further research in this area were proposed

A FUNCTION PROPERTY OF POLYTROPHIC PROCESS WITH ASPECT OF TANGENT CONSTRUCTION

In this paper, starting from general tangent equation in arbitrary point of specified curve, using principles of differential geometry and given mathematical transformation tangent equation of polytrophic function in p – v diagram was obtained. This form is convenient for solving numerous practical and theoretical problems in engineering thermodynamic by means of graphical method. It was shown that tangent can be constructed easily, using polytrophic equation only, but it is not example with other functions appearing in thermodynamics. Later, in this paper, we have given some methods, which refer to more exact construction of polytrophic and graphical analyze of polytrophic process

Acute leukemia of childhood: A single institution's experience

The aim of this study was to investigate distribution of immunophenotypic and cytogenetic features of childhood acute leukemia (AL) in the cohort of 239 newly diagnosed patients registered at the leading pediatric oncohematology center in the country during a six-year period (1996-2002). With approximately 60-70% of all childhood AL cases in Serbia and Montenegro being diagnosed and treated in this institution the used data represent a valid research sample to draw conclusions for entire country. On the basis of five phenotypic markers, the distribution of immunological subtypes was as follows: 169 (70.7%) expressed B-cell marker CD19 (137 were CD10 positive and 32 CD10 negative), 37 (15.5%) belonged to T-lineage acute lymphoblastic leukemia (T-ALL) (cyCD3 positive), and 33 (13.8%) were acute myeloblastic leukemia (AML) (CD13 positive and/or CD33 positive in the absence of lymphoid-associated antigens). The ratio of males and females was 1.5:1. Most of the cases were between the ages of 2 and 4, and were predominantly B-lineage acute lymphoblastic leukemia (B-ALL) cases. Another peak of age distribution was observed at the age of 7. The frequency of T-ALL (18% of ALL) was similar to that reported for Mediterranean countries: France (19.4%), Greece (28.1%), Southern Italy (28.3%), and Bulgaria (28.0%). Cytogenetic analyses were performed in 193 patients: 164 ALL and 29 AML. Normal karyotype was found in 57% of ALL and in 55% of AML patients, while cytogenetic abnormalities including structural, numerical, and complex chromosomal rearrangements were found in 43% of ALL and in 45% of AML patients. Our results represent a contribution to epidemiological aspects of childhood leukemia studies

A FUNCTION PROPERTY OF POLYTROPHIC PROCESS WITH ASPECT OF TANGENT CONSTRUCTION

In this paper, starting from general tangent equation in arbitrary point of specified curve, using principles of differential geometry and given mathematical transformation tangent equation of polytrophic function in p – v diagram was obtained. This form is convenient for solving numerous practical and theoretical problems in engineering thermodynamic by means of graphical method. It was shown that tangent can be constructed easily, using polytrophic equation only, but it is not example with other functions appearing in thermodynamics. Later, in this paper, we have given some methods, which refer to more exact construction of polytrophic and graphical analyze of polytrophic process

Swelling, Mechanical and Antimicrobial Studies of Ag/P(HEMA/IA)/PVP Semi-IPN Hybrid Hydrogels

A simple and fast approach to the design and production of new hybrid polymeric biomaterials with silver particles is presented in this work. Silver/semi-interpenetrating network hybrid hydrogels (Ag/semi-IPNHHs) were prepared through an optimized solution crosslinking copolymerization of 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA), in the presence of PVP, a silver salt and a reducing green agent (Ag/P(HEMA/IA)/PVP). PVP was chosen due to its protective, reduction, and nucleation properties in the production of metal particles. The structure of the Ag/semi-IPNHH was characterized by Fourier transform infrared spectroscopy (FTIR). The presence of silver and PVP in the network was confirmed by FTIR spectra. The results obtained by dynamic mechanical analysis (DMA) showed good mechanical properties for all samples. The swelling studies of Ag/P(HEMA/IA)/PVP were conducted in the temperature range of 25-55 degrees C, in the buffer of pH 7.40. The Ag/semi-IPNHH showed temperature-sensitive swelling properties, with the lower critical solution temperature (LCST) values in the physiologically interesting interval. The antimicrobial activity of the samples was tested using E. coli, S. aureus and C. albicans pathogens. It was concluded that the antimicrobial potential depends on the hydrogels composition and the type of microbes12th Annual YUCOMAT Conference, Sep 06-10, 2010, Herceg Novi, Montenegr

Self-Assembly of Linear Arrays of Semiconductor Nanoparticles on Carbon Single-Walled Nanotubes †

Ligand-stabilized nanocrystals (NCs) were strongly bound to the nanotube surfaces by simple van der Waals forces. Linear arrays of CdSe and InP quantum dots were formed by self-assembly using the grooves in bundles of carbon single-walled nanotubes (SWNTs) as a one-dimensional template. A simple geometrical model explains the ordering in terms of the anisotropic properties of the nanotube surface. CdSe quantum rods were also observed to self-organize onto SWNTs with their long axis parallel to the nanotube axis. This approach offers a route to the formation of ordered NC/SWNT architectures that avoids problems associated with surface derivatization. Both semiconductor quantum dots (QDs) 1 and carbon singlewalled nanotubes (SWNTs) 2 possess interesting and potentially useful optical and electronic properties due to their nanoscale structures. In the case of QDs, quantum confinement in three dimensions produces a size-dependent modification of the electronic band structure, resulting in the formation of discrete electronic states. QDs exhibit unique behaviors such as efficient photoluminescence and photon up-conversion, slowed relaxation and cooling of hot carriers, enhanced lasing, and carrier multiplication via impact ionization. 3 SWNTs, however, consist of sp 2 -hybridized carbon atoms that form the walls of nanometer-wide, seamless cylinders. Past efforts to attach semiconductor nanocrystals (NCs) to nanotubes have focused on forming chemical attachments between the two different nanostructures. In this approach, defects in the nanotube lattice, i.e., any site where the sp 2 -bonded carbon network is broken, are used as sites for chemical bond formation. Such defects are typically present after acid-based purification methods or may be specifically introduced by chemical derivatization. In this paper, we report the formation of organized, onedimensional (1-D) arrays of semiconductor QDs by van der Waals (vdW) adsorption onto SWNTs. Two representative II-VI and the III-V semiconductor NCs, CdSe and InP, respectively, demonstrated linear ordering when adsorbed from nonaqueous colloidal solutions onto high-purity, low-defectdensity SWNTs. The tendency to form linear arrays was greatest when tube-tube alignment was relatively good within bundles and when the QDs were relatively large. The edge-to-edge (ee) separation distance between QDs in the 1-D arrays was ∼18 Å for both the InP and the CdSe QDs, indicating that QD-QD separation is governed by the thickness of the ligand shells, as is the case in two-and three-dimensional QD arrays

Low Temperature Growth of In2O3and InN Nanocrystals on Si(111) via Chemical Vapour Deposition Based on the Sublimation of NH4Cl in In

Indium oxide (In2O3) nanocrystals (NCs) have been obtained via atmospheric pressure, chemical vapour deposition (APCVD) on Si(111) via the direct oxidation of In with Ar:10% O2at 1000 °C but also at temperatures as low as 500 °C by the sublimation of ammonium chloride (NH4Cl) which is incorporated into the In under a gas flow of nitrogen (N2). Similarly InN NCs have also been obtained using sublimation of NH4Cl in a gas flow of NH3. During oxidation of In under a flow of O2the transfer of In into the gas stream is inhibited by the formation of In2O3around the In powder which breaks up only at high temperatures, i.e.T > 900 °C, thereby releasing In into the gas stream which can then react with O2leading to a high yield formation of isolated 500 nm In2O3octahedrons but also chains of these nanostructures. No such NCs were obtained by direct oxidation forTG < 900 °C. The incorporation of NH4Cl in the In leads to the sublimation of NH4Cl into NH3and HCl at around 338 °C which in turn produces an efficient dispersion and transfer of the whole In into the gas stream of N2where it reacts with HCl forming primarily InCl. The latter adsorbs onto the Si(111) where it reacts with H2O and O2leading to the formation of In2O3nanopyramids on Si(111). The rest of the InCl is carried downstream, where it solidifies at lower temperatures, and rapidly breaks down into metallic In upon exposure to H2O in the air. Upon carrying out the reaction of In with NH4Cl at 600 °C under NH3as opposed to N2, we obtain InN nanoparticles on Si(111) with an average diameter of 300 nm

Management of short wave unevenness of the rail head surface

Предмет истраживања у Дисертацији су неравнине малих таласних дужина на горњој површи главе шине у додиру са точком железничког возила. Циљ истраживања је развој методологије за управљање неравнинама малих таласних дужина (λ < 1 m) које настају услед контактног замора шинског челика (RCF). Управљање неравнинама на возној површи главе шине разматрано је у оквирима одрживог развоја железничке инфраструктуре, уз разматрање захтева корисника, железнице, привреде, животне средине, друштвене заједнице и безбедности транспорта. Разматрани су узроци појаве и механизам развоја неравнина, са посебним освртом на шинске дефекте који директно угрожавају безбедност железничког транспорта и негативно утичу на животну средину: head checking, squat, belgrospi и различити типови набораности површи главе шине. Разматране су смернице за развој стратегије управљања RCF дeфeктимa. Дат је преглед метода инспекције за рану детекцију поменутих дефеката. У Дисертацији је испитивана хипотеза да крутост шинске подлоге утиче на појаву и развој неравнина малих таласних дужина на возној површи главе шине. Представљени су резултати истраживања утицаја крутости елемената конструкције горњег и доњег строја на укупну крутост шинске подлоге, као и методе за утврђивање вертикалне крутости. Анализирана је неравномерна крутост шинске подлоге дуж колосека са аспекта конструкције и одржавања. Спроведено је експериментално истраживање утицаја крутости шинске подлоге на појаву и развој дефеката типа squat у станици Панчево Варош применом метода опште и детаљне визуелне инспекције колосека, као и методама електрометрије и сеизмометрије на изабраној мерној деоници. Резултати анализе мерних података указују на утицај променљиве крутости подлоге на појаву и развој squat дефеката. Предложене су смернице за даља истраживања.The subject of the research presented in the Dissertation is a short wave unevenness of the rail head surface in contact with the wheel of the railway vehicle. The research aim is developing a methodology for management of short wave unevenness (λ < 1 m) that occurs due to the contact fatigue of rail steel (RCF). The management of unevenness on the running surface of the rail head is considered within the framework of sustainable development of railway infrastructure, considering the requirements of users, railways, economy, environment, social community and transport safety. The causes of appearance and development mechanism of the unevenness were considered, with particular reference to rail defects that directly threaten the safety of railway transport and adversely affect the environment, such as head checking, squat, belgrospi and different types of surface corrugations of the rail head. Guidelines for the development of the management strategy of RCF defects were considered. An overview of inspection methods for early detection of the mentioned defects was presented. Dissertation investigated the hypothesis that the track stiffness influences the appearance and development of the short wave unevenness of the rail head surface. The research results of the influence of the railway superstructure and substructure on the track stiffness, as well as the methods for vertical stiffness measurement were presented. The uneven track stiffness along the track was analysed from the aspect of the structure and maintenance. An experimental investigation of the influence of track stiffness on the occurrence and development of squat defects in Pančevo Varoš railway station was performed using the methods of general and detailed visual inspection of tracks, as well as electrometric and seismic methods on the test section. The analysis of the obtained measurement data proved the influence of the uneven track stiffness on the occurrence and development of squat defects. Guidelines for further research in this area were proposed

RESEARCH OF CHARACTERISTICS OF PROCESS NEUTRALIZATION OF ACID WASTEWATER BY LIME SLUDGE

Lime sludge which is generated in the industrial processes of water softening is a significant environmental and economic burden, due to increasingly stringent of national and international regulations relating to the management of waste streams. The high content of calcium carbonate in this material opens the possibility of its application in the processes of acidic waste water neutralization. In this paper, a research of characteristics of the process of neutralizing the acidity of water in terms of different initial pH value and flow regime, applying lime sludges which are generated in treatment of salt and fresh water, was conducted. Results of research showed that the initial pH value of water and the presence of NaCl have a significant effect on the solubility of calcium carbonate in the process of neutralization, while the examined flow regime (mixing speed of magnetic stirrer) had a negligible impact