Stellar Evolution with Rotation in PARSEC v2.0: Tracks and Isochrones for Low- and Intermediate-mass Stars

Rotation is always known as an important ingredient in stellar models. Studying the impacts of rotation on stellar structure and evolution is the goal of my thesis. PARSEC models is being widely used in the astronomical com munity over the last decade. Nevertheless, for the first time, the PARSEC rotating stellar tracks and isochrones are provided to the community, with a suitable range of masses and metallicities. Specifically, we consider the mod els from very low mass up to 14M⊙, and the metallicity ranges from 0.004 to 0.017. The PARSEC V2.0 code is used to perform the calculations, and the dedicated sites are created for delivering them to users. The concurrence between rotation and the convective core overshooting phenomenon has been carefully calibrated in previous works. In this project, I inherit this result and adopt the maximum value of core overshooting ef ficiency parameter λov,max = 0.4. A linear growth from zero of stars that do not develop a convective core to this maximum value where stars already have a fully convective core is adopted for stars with masses in the transition region. The shellular rotation is treated as a purely diffusive process under the assumption of Roche model. Seven initial rotation rates are considered from zero to the extremely close critical velocity (namely, ωi = 0 − 0.99). The mass loss process is now applied during the evolution of stars due to the enhancement caused by rotation, with the suitable adopted rates that depend on the mass range. In this project, the low-mass (0.8 ≳ M ≳ 2M⊙) and intermediate-mass (2 ≳ M ≳ 14M⊙) are the main targets of the analysis in this thesis. The effects of geometrical distortion and rotational mixing are clearly seen in the Hertzsprung-Russell diagram of our tracks. We have seen the rotating stars spend their time longer in the Main-Sequence phase with respect to their non-rotating counterparts. Also, the higher core mass they would have at the post-main-sequence phases. Especially in the case of intermediate-mass stars, where the CNO-cycles are the main channel of nuclear burning during the main-sequence, the enhancement (depletion) of surface nitrogen and helium (carbon and oxygen) are the most evidence of rotational mixing. Indeed, the faster stars rotate the more enhancement/de pletion. As a consequence, with our new models, we can reproduce very well the hook feature of the open cluster M67, as well as the “global” fitting. Furthermore, we also see a hint of at least two populations that harbour in the open cluster NGC 6633 to explain the extended main-sequence and the position of the three He-clump stars. Finally, this new collection of stellar tracks and corresponding isochrones are available online at the dedicated websites, and most suitably used for studies of young and intermediate-age open clusters

General Approach for the Sensitivity Analysis and Optimization of Integrated Optical Evanescent-Wave Sensors

The optimization of integrated optical evanescent-wave sensors is dual. For optimal performances, we require waveguides with both maximal sensitivity to the measurand, the quantity intended to be measured, and minimal sensitivities to perturbations. In this context, fully numerical approaches are extremely powerful, but demand huge computer resources. We address this issue by introducing a general and efficient approach, based on the formal derivation of analytical dispersion equations, to express and evaluate all waveguide sensitivities. In particular, we apply this approach to rectangular waveguides, to discuss its accuracy and its use within sensitivity optimization procedures

Interaction between triphenylphosphine or 1,2-bis(diphenylphosphino)ethane with some complexes K[PtCl3(olefin)] (olefin: methyleugenol, safrole, isopropyl eugenoxyacetate)

Novel study on the interaction between K[PtCl3(olefin)] (olefin: methyleugenol, safrole and isopropyl eugenoxyacetate) with TPP and DPPE shows that TPP and DPPE readily replace the olefins to form complexes [PtCl2(TPP)2] (P4), [PtCl2(DPPE)] (P5) and [Pt(DPPE)2]Cl2 (P6). P4 possesses trans configuration when the molar ratio of the mono olefin and TPP of 1:1. When the ratio is 1:2, P4 is a mixture of trans and cis isomers of which trans one is prevailing. The cis isomer trends to convert to trans one in chloroform solvent. P5 and P6 were formed when the molar ratio of mono isopropyl eugenoxyacetate and DPPE of 1:1 and 1:2, respectively. The structures of P4÷P6 were elucidated by Pt analysis, ESI-MS, IR and 1H NMR spectra studies. Keywords. Pt(II) complexes, olefins, phosphine derivatives

RELATIONSHIPS OF TEMPERATURE AND HUMIDITY TO THE BIODEGRADATION OF PETROLEUM HYDROCARBONS IN SOILS

This work focused on monitoring CO2production, microbial growth and residual hydrocarbon concentration during bioremediation experiments performed on laboratory soil microcosms. A natural soil was artificially contaminated with hexadecane and adjusted with inorganic nutrients to stimulate biodegradation. Microbial growth, CO2production and residual hexadecane were periodically monitored at different soil water contents ranging from 0.15 to 0.25 g water g_1 of dry soil and at different temperatures ranging from 20 to 25oC. Results showed that the humidity has a greater effect on microbial activity and contaminant degradation than the temperature. The study established the experimental regression equation of temperature and humidity to the hexadecane mineralization rate, an important parameter in assessing the ability to convert organic carbon into inorganic carbon. The difference between the results of the hexadecane mineralization rate obtained from the experiment and calculated from the regression equation is not too high, from 2% to 20%

Adaptive Fuzzy Proportional Integral Sliding Mode Control for Two-Tank Interacting System

This paper presents an adaptive fuzzy proportional integral sliding mode control (AFPISMC) for two-tank interacting system (TTIS). In order to maintain the desired liquid level of the TTIS and meet the reference values for attenuated chattering problems, this paper proposes a combination of a sliding mode control (SMC) with a proportional integral (PI) sliding surface and a fuzzy inference system. Fuzzy logic and the universal approximation theorem of fuzzy systems are used to approximate the uncertain function in the PISMC. The stability of the control system is proved by the Lyapunov theory. The simulation results of the proposed method in MATLAB/Simulink were compared to a fuzzy control, a sliding mode control with conditional integrals, a fuzzy-PID control, and a conventional PID control. The comparison results showed that the proposed controller was most effective when the rising time reached 0.2375 s, the percent of overshoot was 0%, the steady state error converged to zero, the settling time was 0.4612 s, and chattering was reduced

Adaptive Sliding Mode Control Based on Fuzzy Logic and Low Pass Filter for Two-Tank Interacting System

An adaptive sliding mode control (SMC) based on fuzzy logic and low pass filter is designed in this research. The SMC is one of the most widely accepted robust control techniques. However, the main disadvantage of the SMC is chattering phenomena, which inhibits its usage in many practical applications. Fuzzy logic control has supplanted conventional techniques in many applications. A major feature of fuzzy logic is the ability to express the amount of ambiguity in individual perception and human thinking. In this study, a fuzzy inference system is applied to approximate the function in the SMC law. A low pass filter is used to reduce chattering phenomena around the sliding surface. The stability of the control system is proved by the Lyapunov theory. The proposed controller is tested to position tracking control for two-tank interacting system. This system has been applied in process industries like petroleum refineries, chemical, paper industries, water treatment industries. Simulation results in MATLAB/Simulink show that the proposed algorithm is more effective than the sliding mode control, sliding mode control using conditional integrators and fuzzy control without steady-state error, the overshoot is 0 (%), the rising time achieves 2.187 (s) and the settling time is about 3.9133(s)

Adaptive Fuzzy Proportional Integral Sliding Mode Control for Two-Tank Interacting System

This paper presents an adaptive fuzzy proportional integral sliding mode control (AFPISMC) for two-tank interacting system (TTIS). In order to maintain the desired liquid level of the TTIS and meet the reference values for attenuated chattering problems, this paper proposes a combination of a sliding mode control (SMC) with a proportional integral (PI) sliding surface and a fuzzy inference system. Fuzzy logic and the universal approximation theorem of fuzzy systems are used to approximate the uncertain function in the PISMC. The stability of the control system is proved by the Lyapunov theory. The simulation results of the proposed method in MATLAB/Simulink were compared to a fuzzy control, a sliding mode control with conditional integrals, a fuzzy-PID control, and a conventional PID control. The comparison results showed that the proposed controller was most effective when the rising time reached 0.2375 s, the percent of overshoot was 0%, the steady state error converged to zero, the settling time was 0.4612 s, and chattering was reduced

Challenges in Speaking English in ASEAN

Studies reveal that learning English by non-native individuals within any country across the globe increases the nature of problem-solving criteria adopted worldwide. People tend to adopt and embrace a new trajectory that can enhance efficiency in solving the problems that the designated group might face. Immigrants tend to meet a lot of issues within the nation. The leading cause of these problems is usually a result of the language barrier, which can be easily breached by introducing the English language within the region of ASEAN (Yi & Jang 2020). Proficiency in the language creates an atmosphere that is conducive for the aspect of solving the existing problems within the environment. The nature of problem-solving is sophisticated and crucial for the operations exhibited within ASEAN. This paper outlines the challenges faced by ASEANic people when speaking English. &nbsp