Nickel Catalysts on Porous Ceramic Supports for the Reaction of Partial Oxidation of Propane to CO and H2

In this paper synthesis, textural and structural properties as well as selectivity of Ni based catalysts for partial oxidation of propane to CO and H2 are given. The influence of aluminosilicate and magnesia based porous ceramic supports on catalyst performance is emphasized. The influence of concentration of impregnation solution, number of successive impregnations and nature of modifier was investigated. The catalytic test was performed in order to define the catalyst with the highest selectivity toward CO and H2 while the presence of side-products like CO2, CH4, and coke as well as unreacted C3H8 are reduced to minimum. All synthesized catalysts samples were dominantly macroporous. The selectivity of catalysts increased with presence of modifiers in the following order: CaO < MgO < Al2O3. The selectivity of studied catalysts is governed mainly by two structural parameters: nickel loading and nickel crystallite size. The comparison of the best performing aluminosilicate and magnesia supported catalysts with Al as modifier revealed that the latter express somewhat lower selectivity particularly toward CO

Research and development of procedures and models for robust design of automotive gearboxes

Развијене процедуре у овом раду заснивају се на коришћењу поузданости машинског система и компонената као гранични услов за одређивање конструкцијских и других параметара, као својство компонената и као показатељ квалитета система...Procedures developed in this paper are based on the use of reliability of mechanical systems and components as a boundary condition to determine the construction and other parameters, such as feature of components and indicator of system quality..

Analysis of Power Losses in Constrained Cycloid Drive

The aim of this paper is to present a theoretical model for efficiency evaluation of a simple cycloid drive train with one degree of freedom (DOF) or constrained cycloid drive. In order to evaluate the efficiency, it is necessary to find the losses generated in the simple cycloid drive, where only losses depending on the load were considered. Expressions for determining speed ratios, efficiency, velocities and forces acting inside the cycloid drive are presented. These expressions are implemented in the theoretical model, where the places where the losses occur are defined. A computer program was created to facilitate analysis and obtain loss values based on different input data. Only load-dependent losses were considered in the theoretical model and computer program. In order to verify the theoretical model, experimental measurements were performed. A physical model of the simple cycloid drive train was created and analyzed on the test bench. The results for "S1" operating mode, i.e. when shaft 2 is stopped, show a mean value of the efficiency of 63.49%, for experimental measurements, while the mean value for theoretical analysis is 65.25%. For the operating mode "S2", i.e. with shaft 1 stopped, the mean value of the experimental measurements of the efficiency is 60.9%, while the theoretical mean value is 62.82%

CONTEMPORARY PLANETARY GEARBOXES AND THEIR CALCULATION

The increased demands for driver comfort and stringent pollution control measures have resulted in a revival of planetary gearboxes for road applications, due to their possibility to change the transmission ratio under load in synchronism with engine operation. Modern boxes provide as many transmission ratios as possible from the least possible number of simple component planetary gear trains (PGTs) by providing links between elements of multiple component PGTs. The application conditions decide to prioritize either the maximum number of transmission ratios, or ruggedness and reliability. Power circulation, hollow shafts, or complex planet carrier arrangements are avoided if possible. This paper deals with multispeed complex PGTs composed of at least two interconnected simple component PGTs controlled by brakes and clutches. Several variants of complex PGTs and the placement of brakes and clutches on external shafts of the gear trains are examined, and the transmission ratio functions derived. The kinematics of multi speed gear trains are obtained as combinations of two or more two-speed gear trains. An analysis of several contemporary gearbox layouts is provided together with the transmission ratio functions, together with an overview of the procedure for the calculation of creation of multi-speed gear trains is given

The influence of synthesis parameters on textural properties of modified Ni-based catalysts supported on magnesia for production of reducing atmosphere

Reducing gas atmosphere containing CO and H2 as processing gasses is commonly used in the metal processing industry for heat treatment of special metals. For the production of reducing atmosphere conventionally are employed nickel catalysts on various ceramic supports. Since the process takes place at high temperature, thermal stability and textural properties of catalysts are of particular interest. In this work magnesia supported nickel catalysts were synthesized. The catalyst synthesis consisted of single or successive impregnations with nitrate precursor salts of nickel and modifiers (Al, Ca and Mg), followed by thermal catalyst activation. Nickel:- modifier molar ratio was 10:1.The solid to liquid mass ratio was 1:3. The concentration of Ni in impregnation solution varied from 1.0 to 3.0 moldm-3. Mercury intrusion porosimetry was used for textural characterization since the synthesized catalysts were predominantly macroporous. The impregnation led to decrease of total pore volume, broadening and shifting of pore size distribution curve towards smaller pores. These changes were enhanced with the increase of initial concentration of Ni solution and number of successive impregnations as well as the nature of modifier. The Ni-catalyst modified with Al showed the best textural properties

Bone Regeneration Potential of Periodontal Ligament Stem Cells in Combination with Cold Atmospheric Plasma-Pretreated Beta-Tricalcium Phosphate: An In Vivo Assessment

In regenerative bone tissue medicine, combining artificial bone substitutes with progenitor cells is a prospective approach. Surface modification via cold atmospheric plasma (CAP) enhances biomaterial–cell interactions, which are crucial for successful bone regeneration. Using a rabbit calvarial critical-size defect model, we assessed the use of CAP-pretreated beta-tricalcium phosphate (β-TCP), alone or with periodontal ligament stem cells (PDLSCs), for bone regeneration. Histological and histomorphometric analyses at two and four weeks revealed significantly improved bone regeneration and reduced inflammation in the CAP-treated β-TCP with PDLSCs compared to β-TCP alone. Immunohistochemical analysis also showed an increase in the bone healing markers, including bone morphogenic proteins 2 and 4, runt-related transcription factor 2, collagen-1, and osteonectin, after two and four weeks in the CAP-treated β-TCP implants with PDLSC. This in vivo study demonstrates for the first time the superior bone regenerative capacity of CAP-pretreated β-TCP seeded with PDLSCs, highlighting the therapeutic potential of this combined approach in osteoregeneration

TRANSITION IN TERMS OF GLOBALISATION

One of the essential constituents of the term transition, in Serbia as well as in other postsocialistic countries, refers to the transition from one development concept onto another one (extensive and mobilising), which is completely different (market-based and innovation-oriented). Market behaviour rules have changed to a great extent, as well as the increasingly present innovations in the field of technology, and introduced certain innovations in business orientation of companies. The struggle for market share is becoming more aggressive and dynamic enabling the survival of exclusively those companies which have implanted high flexibility and innovation levels into their business ambience. Globalisation is inherent in capitalism, it is its constituent logic. In future, new rules will have to be brought which would allow of the managment function to be performed within the complete business policy mutually agreed upon betwen the representatives of the capital owner and those of the personell. These regulations are necessary for long-term efficiency and profitability of private sector, as well as for the final success of economy

SCIENTIFIC TECHNOLOGY PARKS

The overall objective of the development of industrial companies in the Technology park is the introduction of economically profitable production with efficient use of renevvable resources and use of highest environmental standards. Realization of the basic development goal of the Technology Park includes: creating a favorable business atmosphere in the local environment, attractive for foreign and domestic investors, supporting the establishment of small and medium enterprises using different models of joint ventures and foreign direct investment