This manuscript describes a unique class of locomotive robot: A soft robot, composed exclusively of soft materials (elastomeric polymers), which is inspired by animals (e.g., squid, starfish, worms) that do not have hard internal skeletons. Soft lithography was used to fabricate a pneumatically actuated robot capable of sophisticated locomotion (e.g., fluid movement of limbs and multiple gaits). This robot is quadrupedal; it uses no sensors, only five actuators, and a simple pneumatic valving system that operates at low pressures (<10 psi). A combination of crawling and undulation gaits allowed this robot to navigate a difficult obstacle. This demonstration illustrates an advantage of soft robotics: They are systems in which simple types of actuation produce complex motion.biomimetic | mobile R obotics developed to increase the range of motions and functions open to machines, and to build into them some of the characteristics [including autonomous motion (1-3), adaptability to the environment (4-7), and capability of decision making (8, 9)] of animals, particularly animals with skeletons. Most mobile robots are built with hard materials (hard robots), either by adding treads or wheels (10, 11) to conventional machines to increase their mobility, or by starting with conceptual models based on animals [e.g., Big Dog (12) and many others (13-15)], and replicating some of their features in hard structures. Although robotics has made enormous progress in the last 50 years, hard robots still have many limitations. Some of these limitations are mechanical, and include instability when moving in difficult terrain; some have to do with the ranges of motions afforded by actuators and structures (e.g., metal rods, mechanical joints, and electric motors); some stem from the complexity in control (especially when handling materials and structures that are soft, delicate, and complex in shape). Hard robots fabricated from metals are also often heavy and expensive, and thus are not suitable for some applications.New classes of robots may thus find uses in applications where conventional hard robots are unsuitable. We are interested in a unique class of robots: That is, soft robots fabricated in materials (predominantly elastomeric polymers) that do not use a rigid skeleton to provide mechanical strength. The objective of this work is to demonstrate a soft robot that requires only simple design and control to generate mobility. In this demonstration, we begin to address some of the issues that have limited the development of soft robots. Instead of basing this and other designs on highly evolved animals as models, we are using simpler organisms [e.g., worms (16) and starfish (17)] for inspiration. These organisms, ones without internal skeletons, suggest designs that are simpler to make and are less expensive than conventional hard robots, and that may, in some respects, be more capable of complex motions and functions. Simple, inexpensive systems will probably not replace more complex and expensive ones, but may have different...

We analyze a joint pricing and inventory control problem for a perishable product with a fixed lifetime over a finite horizon. In each period, demand depends on the price of the current period plus an additive random term. Inventories can be intentionally disposed of, and those that reach their lifetime have to be disposed of. The objective is to find a joint pricing, ordering, and disposal policy to maximize the total expected discounted profit over the planning horizon taking into account linear ordering cost, inventory holding and backlogging or lost-sales penalty cost, and disposal cost. Employing the concept of L -concavity, we show some monotonicity properties of the optimal policies. Our results shed new light on perishable inventory management, and our approach provides a significantly simpler proof of a classical structural result in the literature. Moreover, we identify bounds on the optimal order-up-to levels and develop an effective heuristic policy. Numerical results show that our heuristic policy performs well in both stationary and nonstationary settings. Finally, we show that our approach also applies to models with random lifetimes and inventory rationing models with multiple demand classes.

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An interconnected multi-microgrids (IMMGs) system takes advantage of various complementary power sources and effectively coordinates the energy sharing/trading among the MGs and the main grid to improve the stability, reliability, and energy efficiency of the system. The core of this structure is to achieve the optimal distribution of energy sharing through proper strategies. However, the volatility and intermittent characteristics of renewable resources, time-varying loads in the MGs, their correlated power generations, and the coupled energy among the MGs during energy trading, all bring about new challenges to achieving a stable operation and optimal scheduling in the power system. Many solutions have been proposed to solve these problems. In this paper, we provide an overview of the current energy management systems (EMS) in IMMGs, focusing on the IMMG structure, EMS objectives, timescales, and scheduling optimization structure. We then provide a review of the distributed optimization algorithms in IMMGs. We conclude this survey with a discussion of future directions. INDEX TERMS Smart grid, microgrid (MG), interconnected multi-microgrids (IMMG), energy sharing, energy management.