Papers by Keyword: Transition State

Abstract: Computer and information technology has evaded our every aspect of life. Information technology is seen in all aspect of the individual from banking and investing to shopping and communicating through the use of the internet services such as emails and chat rooms. Organizations and industries also utilize computer and information technology to collect information on individuals leading to the creation of warehouse of databases that enable them to achieve their objectives. In a distributed network environment today, information security is a very important issue in ensuring a safe computing environment.

Abstract: The decarbonylation of acetaldehyde assisted by Ni⁺², which was selected as a representative system of transition metal ions assisted decarbonylation of acetaldehyde, has been investigated using density functional theory (B3LYP) in conjunction with the 6-31+G** basis sets in C,H,O atoms and Lanl2dz basis sets in Ni atom The geometries and energies of the reactants, intermediates, products and transition states relevant to the reaction were located on the triplet ground potential energy surfaces of [Ni, O, C₂,H₄]⁺². Our calculations indicate the decarbonylation of acetaldehyde takes place through four steps, that is, encounter complexation, CC activation, aldehyde H-shift and nonreactive dissociation, it is that CC activation by Ni⁺² that lead to the decarbonylation of acetaldehyde.

Abstract: The reaction of Et₃GeCH=CH₂ + Et₃SiOH → Et₃SiO–Ge–Et₃ + CH₂=CH₂ has been studied using quantum chemistry methods. Geometries of reactants, transition states, and products have been optimized respectively at the b3lyp/6-311+g(2d,2p) level. The rate constants were evaluated using canonical variational transition state theory (CVT) and canonical variational transition state theory with small-curvaturetunneling contributions (CVT/SCT) over the temperature range of 200-3500K. The CVT/SCT rate constants exhibit typical non-Arrhenius behavior, and a three-parameter rate-temperature formula has been fitted as follows: k(T)=1.43×10^-38T ^5.41exp(-13200/T) (in units of cm³ molecule^-1s^-1).

Abstract: For power distribution systems, recognizing the single-phase ground fault is very difficult because there are several faults with similar features. This paper presents a novel method that can help to overcome this difficulty. The idea is to turns the original fault info into a whole system with transient state, steady state and transition state. Theoretical analysis, computer simulation and lab experiments verified the effectiveness of the proposed method.

Abstract: The electrochemical reaction in the cathode plays an important role on the performance and application of PEM fuel cell. In this paper, mechanism of oxygen reduction reaction in the cathode of PEM fuel cell is simulated based on molecule dynamics and quantum mechanics. The most probable electrochemical reaction process in the cathode is obtained by analyzing transition state and free energy of oxygen reduction reaction with the catalysis of Pt. Simulation results show that 2e reaction mechanism is more applicable to oxygen reduction reaction in the cathode than 4e reaction mechanism; according to the potential energy barrier, the process from hydrogen peroxide to water is the controlling process of oxygen reduction; comparison with the total free energy, when the fuel cell temperature is 353K, the thermodynamics potential of PEM fuel cell is the highest. Simulation results are very helpful to understanding reaction mechanism in the cathode of PEM fuel cell and optimizing its performance.

Abstract: Concerned that management of job-oriented accidents has remained a daunting challenge for all stakeholders in Nigeria oil-industry, a longitudinal study was made to appraise the patterning of episodic incidence of industrial accidents in a typical oil and gas company operating in the Nigeria flank of the oil-rich Niger Delta Basin. A 10-year historical accident data were characterized and found to have absorbing chain properties. Four open-and-shot transition states namely : fatality, accident, near-miss and unsafe act, that are subject to ergodicity, were identified and used to craft a value digraph which define the stable transition probability matrix. The results, which suggest that on the average, 59% of staff are wasted through fatality or severe accidents, also points to escalating rates of fatalities and disabilities stemming from accidents thus calling for the need to review the existing hazard operations studies (HAZOPS) and hazard identification schemes (HAZIDS) so as to assist in whittling down, as low as reasonably practicable, the perceived unpleasant trend. The author is of the opinion that industrial accident victims, unlike in road traffic accident (RTA), habituate several times before entering the absorbing state.