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Heterogeneous surface with superhydrophilic/superhydrophobic stripes (HS-s/sS) has great practical significance, which can be used in fuel cell water management, condensation heat transfer enhancement, underwater drag reduction. Herein, a fast and simple method for uniform HS-s/sS on several mesh materials, including copper, stainless steel, and nickel, is achieved by using picosecond (ps) laser line-by-line scanning. Note that the scanning period between the lines is kept constant during processing, the HS-s/sS is formed by self-organized, while the similar structure cannot be processed on solid metal surfaces using the same parameters. The processing parameters, including scanning speed, defocus amount (DA), scanning period, and single pulse energy are systematically investigated to optimize HS-s/sS fabrication. It is found that the period of processed stripe on the mesh material is ∼1 mm, which is much larger than the scanning period. Interestingly, the as-prepared mesh surface show superhydrophobicity in the convex striped surface and superhydrophilicity in concave striped parts. The scanning electron microscopy results show that the structures on convex stripe are mainly composed of disordered hill-like structures, while the structures on the concave stripe mainly consist of periodic nanostripe structures. Moreover, the proportion of oxygen on the convex stripe is obviously higher than that on the concave stripe. The underlying mechanism of the HS-s/sS formation can be attributed to the interference between surface phonon polaritons (SPP) and the incident picosecond laser, as well as surface shock wave caused by the picosecond laser. We believe that such functional surfaces will be promising candidates for controlling liquid motion and fluid diversion processes.

Bioinspired slippery surfaces with excellent abilities, such as antifouling, anticorrosion, and drag reduction, have gained increasing attention due to their multifunction in chemistry, biology, and medicine. However, the present thermally responsive methods used for in situ paraffin-infused slippery surfaces (PISS) are usually based on a surface heat source or certain specific photothermal materials, which seriously hinders their practical applications. Herein, we present a kind of in situ PISS processed by femtosecond laser on nickel (Ni) foam with reversible droplet behavior between sliding and pinning controlled by a point heat source. By alternately loading and unloading the point heat source, switchable wettability for liquid droplets can be achieved. The reaction time of this smart surface to the temperature change is 4.47 ± 1.14 s. The relationship between droplet volumes and inclined angles on four different surfaces is quantitatively investigated. Furthermore, the as-prepared PISS display an impressive self-healing ability. In addition, by flexibly changing the action path of the point heat source, the droplet can realize the movement of different curves. This functional surface and in situ control method will be a promising candidate for manipulating droplet directional sliding behavior and smart temperature-responsive surfaces.

In the parking lots of public commercial areas, such as shopping malls, hospitals, and scenic spots, the parking spaces with electric vehicle (EV) charging facilities are often occupied by ordinary cars. How to regulate the parking order in the parking lot is a key issue in the operation and management of the parking facilities. In this paper, a method of assessing parking fees for vehicles parked at the charging facilities is proposed based on an economic penalty strategy, including fixed-penalty and dynamic-penalty strategies. First, a traffic flow model of the parking lot in public area is established. Then, a price and consumption model of parking fees and parking lot utilization is established, along with different penalty strategies. Finally, taking the parking lot of a shopping mall as an example, the penalty strategies are optimized through particle swarm optimization (PSO) algorithm. The simulation results show that the method proposed can help to improve the utilization of EV charging facilities in parking lots and guide the orderly parking and charging of EVs at the same time.

As a strong supplement of bulk power system, microgrid has become an important part of smart grid and has wide prospects in residential application. The increasing penetration of renewable energy and electric vehicles has bring numerous challenges to the stability of microgrid system. The stable and economic dispatch strategy plays a major role in the operation of such a distributed power system. This paper presents a robust economic dispatch strategy for residential microgrid. Considering the worst scenario of available wind power, this strategy schedules EV charging load, outputs of distributed generators for the sake of reducing operation cost under variable practical constrains such as power balance constrain, EV charging constrains and constrains of distributed generators. A charging time based grouping dispatch approach is proposed to schedule the charging of numerous electric vehicles. Numerical results show that the proposed dispatch strategy is robust and reliable.