In this study, nonlinear vibration of axially moving strings in thermal environment is investigated. The vibration characteristics of the system such as natural frequencies, time domain response and stability states are studied at different temperatures. The velocity of the axial movement is assumed to be constant with minor harmonic variations. It is presumed that the system and the environment are in thermal equilibrium. Using Hamilton’ s principle, the system equation of motion, and t† he boundary conditions are derived and then solved by applying Multiple Time Scales (MTS) method. The effect of temperature on the vibration characteristics of the system such as linear and nonlinear natural frequencies, stability, and critical speeds is investigated. Considering ideal and non-ideal boundary conditions for the supports, nonlinear vibration of the system is discussed for three different excitation frequencies. The bifurcation diagrams for ideal and non-ideal boundary conditions are presented under the influence of temperature at various speeds.

Jasmine flower belonging to Oleaceae family is cultivated in temperate places across the globe which has more than 200 species. This flower has traditional, religious, social, spiritual and medicinal benefits. It is considered as symbol of beauty, deep affection, happiness and elegance. It is the National flower of many countries. Due to its charming fragrance, it is extensively used in perfume industry. The vital ingredient of jasmine aroma is due to the amalgamation of phytochemicals and alcoholic compounds.  In India these flower strings have special importance among the fairer gender. In South India, strings of Jasmine flower are worn by lactating women. It is believed to produce increased lactopoiesis and prolong the lactational amenorrhoea. The mechanisms can be the activation of olfactory area by olfactory nerve or stimulants crossing blood brain barrier triggering a neuroendocrine response.

The buckling behavior of rod strings in wellbore is one of the key issues in petroleum engineering. The slender rod strings in vertical wellbore were selected as research objects. Based on the energy method, the critical load formulas of sinusoidal and helical buckling were derived for the string with the bottom of the wellbore pressure. According to the sinusoidal and helical buckling’s geometry of the pressurized column, the contact friction state of post‐buckling between the rod strings and the wellbore was considered. This paper adopted Lagrange multiplier method to describe sliding displacement boundary conditions of wellbore and introduced gravitational potential energy and friction resistance dissipated energy in the energy method. The contact forces and friction resistances between the rod string and wellbore were derived in vertical wells. The post buckling experimental apparatus was also developed in this paper. The sinusoidal and helical buckling critical loads and friction resistances were derived under different loads. The experimental results are consistent with the theoretical results. Therefore, this article would provide an effective method for buckling column such as drilling and coiled tubing.

This paper presents a model-based approach for the global maximum power point (GMPP) tracking of solar strings under partial shading conditions. In the proposed method, the GMPP voltage is estimated without any need to solve numerically the implicit and nonlinear equations of the photovoltaic (PV) string model. In contrast to the existing methods in which first the locations of all the local peaks on the P-V curve are estimated and next the place of the GMPP is selected among them, the suggested method estimates directly the GMPP without any need for the evaluation of the other local peaks. The obtained GMPP voltage is then given as a reference value to the input voltage controller of a DC-DC boost converter to regulate the output voltage of the solar string at the GMPP voltage in various irradiation conditions. Furthermore, the values of the temperature and irradiation level of each PV module within the PV string are estimated, and therefore, the proposed method does not need to thermometers and pyranometers. This makes it as a reliable and low-cost GMPP tracking method. The theoretical aspects on which the proposed GMPP algorithm is established are also discussed. The comparison of the numerical results of the suggested GMPP tracking scheme with the existing methods at different environmental conditions shows the satisfactory operation of the proposed technique from the speed and accuracy point of views.