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This paper studies the vibrational motion of a dynamical system connected to an electromagnetic device, which is one of the energy harvesting (EH) devices that transform the vibrational motion into electric energy. This system has three degrees-of-freedom (DOF) and consists of two linked parts attached together; one is a nonlinear Duffing oscillator, and the other is a nonlinear damping spring pendulum. The regulating equations of motion (EOM) are achieved utilizing Lagrange’s equations and solved analytically applying the approach of multiple scales (AMS) till the third order of approximation. The accuracy of the attained solutions has been examined by comparing them with the numerical ones of the EOM. The time histories of the solutions and the nonlinear stability analysis of the modulation equations are represented graphically in various plots. The Poincaré maps and phase portraits diagrams displayed the stable behavior of the studied dynamical system. In addition, the different ranges of the stabilities are examined and discussed. In the electromagnetic device, the output power and current time series are depicted as a function of different values of the damping coefficients, excitation amplitudes, and load resistance. It is noted that the output current and power are dropped when the damping coefficient is raised. On the other hand, the increment of the excitation has a positive effect on the electrical generation and produces increment of the output power and current. Furthermore, the output power grows when the total resistance increases to accommodate the applied load. The EH device generates high output current and power at low-frequency values. The significance of this work is limited to the numerous uses of its outcomes in everyday life, such as powering medical devices, serving as a power supply for sensors, and serving as a backup energy source for some electronic devices.

The charged-particle production ratios $\bar{p}/p$, $K^-/K^+$, $��^-/��^+$, $(p + \bar{p})/(��^+ + ��^-)$, $(K^+ + K^-)/(��^+ + ��^-)$ and $(p + \bar{p})/(K^+ + K^-)$ are measured with the LHCb detector using $0.3 {\rm nb^{-1}}$ of $pp$ collisions delivered by the LHC at $\sqrt{s} = 0.9$ TeV and $1.8 {\rm nb^{-1}}$ at $\sqrt{s} = 7$ TeV. The measurements are performed as a function of transverse momentum $p_{\rm T}$ and pseudorapidity $��$. The production ratios are compared to the predictions of several Monte Carlo generator settings, none of which are able to describe adequately all observables. The ratio $\bar{p}/p$ is also considered as a function of rapidity loss, $��y \equiv y_{\rm beam} - y$, and is used to constrain models of baryon transport. Incorrect entries in Table 2 corrected. No consequences for rest of paper

This study examines the impact of oil price uncertainty on mergers and acquisition (M&A) activity in the oil and gas sector. Analyzing this industry enables us to construct a natural forward-looking measure of oil price uncertainty, namely the implied crude oil volatility. Using a sample of U.S. firms in the oil and gas sector from 1994–2018 containing 4,323 announced transactions, we document that oil price uncertainty is negatively related to future M&A activity. Uncertainty is mainly a driver of horizontal and vertical M&A activity, where upstream firms are more affected by this uncertainty than downstream firms. Our results lend support to a real options explanation of investment under uncertainty where firms choose to defer investments as a response to increased uncertainty.

Energy harvesting is a useful technique for various kinds of self-powered electronic devices and systems as well as Internet of Things technology. This study presents a two-degrees-of-freedom (2DOF) electromagnetic energy harvester that can use environment vibration and provide energy for small electronic devices. The proposed harvester consists of a cylindrical tube with two moving magnets suspended by a magnetic spring mechanism and a stationary coil. In order to verify the theoretical model, a prototype electromagnetic harvester was constructed and tested. The influence of key parameters, including excitation acceleration, response to a harmonic frequency sweep, and electromechanical coupling on the generated characteristics of the harvester, was investigated. The experimental and theoretical results showed that the proposed electromagnetic energy harvester was able to increase the resonance bandwidth (60–1200 rad/s) and output power (0.2 W). However, due to strong nonlinearity, an unstable region occurred near the main first resonance, which resulted from the Neimark–Sacker bifurcation.

Abstract Grape pomace is a by-product of the wine making industry with great availability and energetic potential. Torrefaction is a pre-treatment that may enhance the biomass quality as a fuel, and consists in exposing the biomass to an inert atmosphere at a temperature between 200 °C and 300 °C. This study evaluates the combustion characteristics of raw and torrefied grape pomace in a thermogravimetric analyzer and in a drop tube furnace. Initially, the raw grape pomace was torrefied in an argon inert atmosphere at 260 °C. Subsequently, the combustion of the raw and torrefied grape pomace was examined in the thermogravimetric analyzer through non-isothermal runs at a heating rate of 10 °C/min from room temperature to 800 °C. Finally, the combustion of both biomass residues was evaluated in the drop tube furnace at 1100 °C. The data reported includes gas temperature, major gas species concentration and particle burnout measured along the axis of the drop tube furnace. The main conclusions of this study are (i) for the devolatilization stage, the thermogravimetric data yielded apparent activation energy values of 84.9 and 85.2 kJ mol−1, and for the char oxidation stage of 137.5 and 109.2 kJ mol−1 for the raw and torrefied grape pomace, respectively; (ii) the NOx concentrations along the drop tube furnace were always higher for the combustion of the torrefied grape pomace than for the combustion of the raw grape pomace because the former residue has a higher nitrogen content; and (iii) the burnout values along the drop tube furnace were always lower for the combustion of the torrefied grape pomace than for the combustion of the raw grape pomace because the former residue has a lower volatile content and a higher fixed carbon content.