Mechanisms of chromium deposition and dissolution under direct and pulse reverse plating conditions

Baths containing sulphuric acid as catalyst and others with selected secondary catalysts (methane sulphonic acid - MSA, SeO2, a KBrO3/KIO3 mixture, indium, uranium and commercial high speed catalysts (HEEF-25 and HEEF-405)) were studied. The secondary catalysts influenced CCE, brightness and cracking. Chromium deposition mechanisms were studied in Part II using potentiostatic and potentiodynamic electroanalytical techniques under stationary and hydrodynamic conditions. Sulphuric acid as a primary catalyst and MSA, HEEF-25, HEEF-405 and sulphosalycilic acid as co-catalysts were explored for different rotation, speeds and scan rates. Maximum current was resolved into diffusion and kinetically limited components, and a contribution towards understanding the electrochemical mechanism is proposed. Reaction kinetics were further studied for H2SO4, MSA and methane disulphonic acid catalysed systems and their influence on reaction mechanisms elaborated. Charge transfer coefficient and electrochemical reaction rate orders for the first stage of the electrodeposition process were determined. A contribution was made toward understanding of H2SO4 and MSA influence on the evolution rate of hydrogen. Anodic dissolution of chromium in the chromic acid solution was studied with a number of techniques. An electrochemical dissolution mechanism is proposed, based on the results of rotating gold ring disc experiments and scanning electron microscopy. Finally, significant increases in chromium electrodeposition rates under non-stationary conditions (PRC mode) were studied and a deposition mechanisms is elaborated based on experimental data and theoretical considerations

A neuro-fuzzy based combustion sensor for the control of optimal engine combustion efficiency

Modern and advanced control systems for internal combustion engines require accurate feedback information from the combustion chamber. Whereas the in-cylinder pressure sensor provides this information through its close thermodynamic ties with the combustion process, drawbacks in its implementation push research towards other non-intrusive sensing methods. This paper suggests alternative methods of combustion phasing detection relying on measured angular crankshaft speed. Method developed, achieves sensing of angular position of the 50% of mass fraction burned (MFB50) through two steps: calculation of, so called, synthetic torque and its non-linear transformation to a combustion feature estimator through local model. In order to calibrate both parts of this virtual combustion sensor, parameters of a high-fidelity crankshaft dynamic model are identified, and the linear neuro-fuzzy based model is trained with extensive experimentally collected data set. Created virtual MFB50 sensor, demonstrated its performance, on a large test data set comprised of 70% of gathered data

Theoretical Studies on Small Ring Heteropropellanes. Oxapropellanes

Oxa(l.1.l)propellane (2), dioxa(l.1.l)propellane (3), and trio-· xa(l.l.l)propellane (4) have been studied by means of ab initio SCF MO technique at 6-31G* level. The geometry optimization is carried out for these molecules and the parent hydrocarbon (1.1.l)propellane. The bond between the two bridgehead carbon atoms is predicted to be in (2) : 1.503 A, (3) : 1.474 A, and (4) : 1.456 A. These are shorter than the calculated central bond (1.543 A) in (1.1.l)propellane

The Connection Between the Adjacency Matrix and the Boundary Code of Benzenoid Hydrocarbons

An algorithm for setting up adjacency matrices of benzenoid hydrocarbons from their boundary sequences is detailed. A recipe for computing the boundary code of a benzenoid structure from its adjacency matrix is also given. Finally, an automatic procedure is devised for computing approximate TRE values of benzenoids from their boundary sequences via the Gutman-Petrovic formulae

The determination of the mean value of the non-homogenous background radiation and the measurement uncertainty using welch-satterthwaite equation

In this paper, the procedure for determination of the mean value of non-homogenous background radiation and the expression of measurement uncertainty is considered. The background radiation is described using the Student's distribution, and the measurement uncertainty using the Welch-Satterthwaite equation. The proposed algorithm was experimentally verified under well-controlled laboratory conditions and satisfactory results were obtained

The Connection Between the Adjacency Matrix and the Boundary Code of Benzenoid Hydrocarbons

An algorithm for setting up adjacency matrices of benzenoid hydrocarbons from their boundary sequences is detailed. A recipe for computing the boundary code of a benzenoid structure from its adjacency matrix is also given. Finally, an automatic procedure is devised for computing approximate TRE values of benzenoids from their boundary sequences via the Gutman-Petrovic formulae

Detour and Cluj-Detour Indices

Recently proposed Cluj matrices: the Cluj-distance matrix and the Cluj-detour matrix are reviewed. New Harary-type indices on the detour and Cluj-detour matrices are defined. Additionally, the formulae for calculating these indices of cycles are derived. Modeling of boiling points for a set of 32 acyclic and cyclic octanes using Cluj indices and their Harary counterparts is presented. The best structure-boiling point relationships are obtained by means of the multiple linear regression using either combinations of two reciprocal paths numbers (1/p2, 1/p3) and detour and hyper-detour indices or a combination of the same two reciprocal path numbers and Harary indices derived from the edge-defined and path-defined Cluj matrices

Detour and Cluj-Detour Indices

Recently proposed Cluj matrices: the Cluj-distance matrix and the Cluj-detour matrix are reviewed. New Harary-type indices on the detour and Cluj-detour matrices are defined. Additionally, the formulae for calculating these indices of cycles are derived. Modeling of boiling points for a set of 32 acyclic and cyclic octanes using Cluj indices and their Harary counterparts is presented. The best structure-boiling point relationships are obtained by means of the multiple linear regression using either combinations of two reciprocal paths numbers (1/p2, 1/p3) and detour and hyper-detour indices or a combination of the same two reciprocal path numbers and Harary indices derived from the edge-defined and path-defined Cluj matrices

Legislative framework of nuclear security in the Republic of Serbia

The paper presents the concept and characteristics of nuclear security, the elements of the nu- clear safety strategy, the legislative framework and the most important solutions from the Law on Radiation and Nuclear Safety and Security. At the international level, the most important entity in this field is the International Atomic Energy Agency, while at the national level, most important is the Directorate for Radiation and Nuclear Safety and Security of Serbia. An important role is played by the Vinča Institute of Nuclear Sciences as the most referential scientific institution in this field, as well as the operational bodies - Nuclear Facilities of Serbia, the Ministry of Internal Affairs, Ministry of Defence, and the Serbian Armed Forces. Engagement of these bodies is carried out in regular peacetime circumstances, emergency situations and wartime. The most important challenges, risks and threats to nuclear security of Serbia were pointed out as well as the need to harmonize norms, procedures and processes in purpose of the strengthening institutional mechanisms in the field of nuclear security

Chemical Graph Theory. V. On the Classification of Topological Biradicals

We have considered skeletal forms for topological (conjugated) biradicals and have examined alternative structural classification schemes for them. In particular, we have looked more closely at the classification proposed by Herndon and Ellzey, based on the multiplicity of the zero eigenvalue and have examined all acyclic forms having 12 or fewer carbon atoms, and all cyclic forms having 8 or fewer carbon atoms. Whlle the present work does not contribute to resolving the controversy as to which type of biradical can be expected to have the singlet, and which the triplet ground state, it provides the possibility of grouping compounds of the same expected ground state and thus allows the deduction of similar properties for members of the same group. Hence, definitive theoretical or experimental results obtained for a new standard species can then be applied to a wider body of biradicals. Examination of the distribution of »unpaired« spin density and the character of bonds which have a constant body type (so-called essentially single or essentially double CC bonds) provided guidance for deriving a number of rules for the construction of larger topological biradical forms by the combination (as fragments) of smaller-sized biradicals or other molecular fragments