Distributed Adaptive Cooperative Tracking of Uncertain Nonlinear Fractional-order Multi-agent Systems

In this paper, the leader-following tracking problem of fractional-order multi-agent systems is addressed. The dynamics of each agent may be heterogeneous and has unknown nonlinearities. By assumptions that the interaction topology is undirected and connected and the unknown nonlinear uncertain dynamics can be parameterized by a neural network, an adaptive learning law is proposed to deal with unknown nonlinear dynamics, based on which a kind of cooperative tracking protocols are constructed. The feedback gain matrix is obtained to solve an algebraic Riccati equation. To construct the fully distributed cooperative tracking protocols, the adaptive law is also adopted to adjust the coupling weight. With the developed control laws,we can prove that all signals in the closed-loop systems are guaranteed to be uniformly ultimately bounded. Finally, a simple simulation example is provided to illustrate the established result.

Sparse Planar Retrodirective Antenna Array Using Improved Adaptive Genetic Algorithm

An improved adaptive genetic algorithm is presented in this paper. It primarily includes two modified methods： one is novel adaptive probabilities of crossover and mutation, the other is truncated selection approach. This algorithm has been validated to be superior to the simple genetic algorithm （SGA） by a complicated binary testing function. Then the proposed algorithm is applied to optimizing the planar retrodirective array to reduce the cost of the hardware. The fitness function is discussed in the optimization example. After optimization, the sparse planar retrodirective antenna array keeps excellent retrodirectivity, while the array architecture has been simplified by 34%. The optimized antenna array can replace uniform full array effectively. Results show that this work will gain more engineering benefits in practice.

Rural coping and adaptation strategies for climate change by Himalayan communities in Nepal

Climate change has major impacts on the livelihoods of forest-dependent communities.The unpredictable weather conditions in rural Nepal have been attributed to a changing climate.This study explored the climate change adaptation and coping strategies that rural communities adopt for the conservation of natural resources and livelihoods in the mid-hills of Nepal.This paper explored major climatic hazards,assessed different coping and adaptation measures,and barrier faced to climate change adaptation based on perceptions by forest-dependent communities.We conducted focus group discussions,questionnaire surveys,and semistructured interviews with local communities and stakeholders.The results showed that rural communities had experienced significant impacts of climate change and variability.In response,they are practicing diverse coping and adaptation strategies,including the construction of bioengineering structures and planting different species that grow quickly and establish promptly.

Sensitivity of tropical cyclone damage costs to integrated wind profile

The dramatic tropical cyclone(TC)damages in coastal areas around the world have gained significant attention from asset owners,policy makers and engineers.The estimate of TC damage for a specific region of interest is informative of the preparedness and resilience of the area subjected to TC hazards,and thus should be conducted using a quantitative approach.A reasonable indicator of TC damage should incorporate not only the TC characteristics(e.g.,intensity,frequency and duration)but also the vulnerability of the TC-prone areas.In this paper,a new indicator is proposed to measure the TC threat,which takes into account both the TC characteristics and the vulnerability of the area.The indicator has two forms:the first one considers the maximum wind speed only and the second incorporates the integrated wind speed profile.The historical damage scenarios along the US East Coast,as well as those in Hong Kong,China,are examined to demonstrate the applicability of the proposed indicator.Results show that the proposed indicator is capable of representing the impact of TC wind field profile on the TC damage costs.The proposed indicator could be further used to project the future TC damages for areas subjected to TC hazards.