The creation of solar steam generators with both high energy conversion efficiency and desired salt-resistant performance is essential for practical desalination. Herein, we report for the first time the fabrication of polypyrrole-coated biomass porous foam as efficient solar steam generators. The as-prepared foams possess a low thermal conductivity of 0.022 W M–1 K–1 for alkali-treated corn straw (CSA) and 0.027 W M–1 K–1 for both microwave- and alkali-treated corn straw (CSMA). Based on their high light absorption (95–100%), superhydrophilic wettability, excellent thermal insulation, and unique aligned channels, the foams show excellent energy conversion efficiency of 89.74, 91.08, and 91.54% for the polypyrrole-coated CSA (P-CSA) and 96.8, 97.05, and 98.32% for the polypyrrole coated CSMA (P-CSMA) at light intensities of 1, 2, and 3 kW m–2, respectively. Importantly, thanks to their aligned hierarchical channels, our generators show extraordinary salt-resistant performance, e.g., the energy conversion efficiencies of P-CSA and P-CSMA were measured to be 62.30 and 94.7% in 20 wt % NaCl at 1 kW m–2 irradiation, respectively. Furthermore, no obvious salt accumulation was observed after 30 d of continuous operation at real sunlight irradiation, implying an outstanding long-term stability for practical solar steam generation.

Solar-driven interfacial water evaporation has attracted increasing interest because of its high photothermal conversion efficiency. However, a big challenge still remains as salt crystallization is a bottleneck issue that hinders their practical solar desalination applicability. Herein, we demonstrate a strategy for construction of a salt-rejection solar steam generation system by designing a migration crystallization device (MCD) using superhydrophilic carbonized green algae (SH-CGA) as photothermal materials. By a surface modification, the SH-CGA shows a superhydrophilic wettability which facilitates fast water transportation, in combination with its low thermal conductivity of 0.042 W m −1 K −1 , high light absorption (98∼100%), and abundant porosity. The prepared SH-CGA exhibits a high evaporation rate of 1.35 kg m −2 h −1 and conversion efficiency of 83% under 1 kW m −2 illumination. Interestingly, we designed a simple MCD by adding a cotton thread into the margin of SH-CGA for preventing surface crystallization. No obvious salt accumulation was observed after 15 d continuous operation at real sunlight irradiation, and the device realizes the simultaneous collection of salt (24.26 g of NaCl crystallization) and water. This result may provide a novel and versatile way for creation of salt-rejection solar steam generation systems with great potential for practical solar desalination.

No abstract

The development of a highly salt-resistant solar evaporator with long-term energy conversion is essential for practical solar desalination. Herein, we first report the ionic liquid-assisted alignment of corn straw-based microcrystalline and oxidized microcrystalline cellulose for preparation of biomass aerogel (abbreviated as CSMCA and CSOMCA) evaporators with low tortuosity channels for salt-assistance solar steam generation. By coating of carbonized cornstalk nanoparticles onto CSMCA and CSOMCA as light-absorbing layers (named C-CSMCA and C-CSOMCA), the light absorption of C-CSMCA and C-CSOMCA reaches 92 and 95%, respectively. The formation of strong H-bonding between pyranoid rings of cellulose in the presence of the ionic liquid would result in a reorientation of microcrystalline cellulose, which makes it possible to create vertically aligned channels of CSMCA and CSOMCA after replacement of solvents, followed by freeze drying. Combined with their low thermal conductivity (0.037 and 0.043 W m–1 K–1), high porosity, and intrinsic superhydrophilicity, C-CSMCA and C-CSOMCA exhibit high evaporation rates (1.44 and 1.36 kg m–2 h–1) and excellent energy conversion efficiencies (88 and 84%). In particular, bearing with vertically aligned channels, C-CSMCA and C-CSOMCA possess excellent salt tolerance for solar desalination due to a rapid resolving and return of the crystalline salt into water, for example, no surface salt crystallization for C-CSMCA after 20 days of continuous evaporation. Moreover, both C-CSMCA and C-CSOMCA have excellent sewage treatment capacity and can efficiently absorb dyes and heavy-metal ions in water bodies, showing great potential in actual desalination and sewage treatment based on their cost-effective, simple, scalable, and green manufacture.

No abstract

No abstract

No abstract

With the rapid development and implementation of autonomous vehicles (AVs), the simultaneous and accurate trajectory tracking problem for such AVs has become a popular research topic. This paper proposes a comprehensive linear time-varying model predictive controller (LTV-MPC) design for a type of AV, aiming to achieve good trajectory tracking in a practical driving scenario. First, a two-degree-of-freedom kinematic model of an AV is established. Next, an error model of the AV’s trajectory tracking system is constructed using linear time-varying theory. A successive linearization is introduced to linearize the nonlinear tracking error model, and a quadratic programming optimization problem is then formulated. Thus, the control sequence for this AV is incorporated into the predictive control framework, and the desired controller can be solved with a relatively higher computational efficiency and lower computational cost. Finally, the effectiveness and performance of the proposed controller are validated via a comparison of simulations conducted using MATLAB software and experiments conducted using a self-established test platform. The results demonstrate that the proposed LTV-MPC method can track the prescribed reference road trajectories with high precision and stability for an AV under various driving conditions.