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This research suggests a new flexible method for the optimal operation of multi-carrier energy systems based on optimization techniques for different weather conditions and seasons. The results apply to different modes (a hot summer day, a cold winter day and a normal day). A new cost function from the operator's point of view is suggested considering the constraints on consumable gas supply and electrical energy in the cold and hot seasons respectively. Furthermore, a novel algorithm is suggested that gives the economical values of energy carriers, final cost, and the percentage of the direct electrical energy supply and outside the hub. In this method, load data, related prices, constraints, and penalties are applied to the suggested model, and afterward hub optimization assists in finding the optimal operation and costs. MATLAB software is used to check the results and the simulation outputs confirming the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

One of the most important issues for the helicopter pilots is the health risk due to the vibration transmitted to the pilot through the seat. In this article, a seat suspension based on negative stiffness structure is presented to decrease the vibration transmitted to the pilot in both vertical and lateral directions without losing the loading capacity of the system. Here, an integrated model of the suspension–cushion–occupant is derived. To generalize the results of system analysis and its usability in other applications, the impact of parameters on the system performance is studied in dimensionless form. Despite coupling between the lateral and vertical directions, the design parameters of the seat suspension are determined in such a way that the system responds simultaneously as a negative stiffness structure in both directions. The system efficiency in vibration damping is assessed by seat effective amplitude transmissibility and transmissibility criteria. In addition, the whole body vibration and impact of the vibration on the pilot body are evaluated using ISO-2631. To verify the system efficiency in more realistic situation, the simulations are performed using the measured vibration data of a Bell-412 helicopter. The results indicate that the vibration amplitude is decreased by about 45% and 48% in the lateral and vertical directions, respectively. The frequency spectrum comparison of the seat and cabin floor reveals 80% reduction of amplitude in fundamental frequency in the vertical direction, whereas it is about 93% in the lateral direction. Furthermore, the level of pilot's comfort and perception is improved that demonstrates better riding quality and reduced vibration environment. [ABSTRACT FROM AUTHOR]

This paper investigates the adaptive fixed-time consensus of a class of multi-agent systems with discontinuous dynamics. First, under the framework of Filippov solutions, a new theorem is established to achieve fixed-time consensus of discontinuous multi-agent systems using the proposed control protocol. Furthermore, an adaptive control protocol is provided in the second theorem that highly improves the control signals of the system. Finally, numerical simulations are worked out to illustrate the effectiveness of our theoretical results. [ABSTRACT FROM AUTHOR]