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Ultralow-emission" standards have started to be implemented for steel plants in China. Flue gas desulfurization (FGD) systems integrating desulfurization and dedusting, common end-of-pipe technologies before the stacks, have been a key process for controlling the complexity of sintering flue gas to meet ultralowemission requirements. This study reports comprehensive analysis of the influence of wet/semidry/dry FGD systems on particulate emissions via a field investigation of five typical sinter plants equipped with various FGD devices. The size distribution and mass concentration of particulate matter (PM) are adjusted to different ranges by these FGD systems. Chemical analysis of the PM compositions shows that 20−95% of the mass of inlet PM is removed by FGD systems, while it is estimated that approximately 17, 63, 59, and 71% of the outlet PMs are newly contributed by desulfurizers and their byproducts for the tested wet limestone, wet ammonia, semidry circulating fluidized bed, and activated coke FGD systems, respectively. The newly contributed compositions of PM 2.5 emitted from these FGD systems are dominated by CaSO 4 , (NH 4 ) 2 SO 4 , CaSO 4 + CaO, and coke carbon, respectively. These results suggest that the deployment of FGD technology should be comprehensively considered to avoid additional negative impacts from byproducts generated in control devices on the atmosphere.

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Magnetic skyrmions are envisioned as ideal candidates as information carriers for future spintronic devices, which have attracted a great deal of attention in recent years. In this paper, we design a spintronic device based on antiferromagnetic skyrmions, which is a single antiferromagnetic skyrmion transistor. The transistor consists of a source, a skyrmion island, a barrier region, and a drain. The barrier region is controlled by strains. We demonstrate the feasibility of the transistor by micromagnetic simulations. We find that the number of skyrmions that can pass the barrier region can be controlled by adjusting the strength of strain in the barrier region and the current density. In an appropriate current-strain region, skyrmions can flow from the skyrmion island to the drain one by one. This mechanism offers a promising route for designing tunable skyrmionic-mechanic devices.

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A reduced surface electric field in an AlGaN/GaN high electron mobility transistor (HEMT) is investigated by employing a localized Mg-doped layer under the two-dimensional electron gas (2-DEG) channel as an electric field shaping layer. The electric field strength around the gate edge is effectively relieved and the surface electric field is distributed evenly as compared with those of HEMTs with conventional source-connected field plate and double field plate structures with the same device physical dimensions. Compared with the HEMTs with conventional sourceconnected field plates and double field plates, the HEMT with a Mg-doped layer also shows that the breakdown location shifts from the surface of the gate edge to the bulk Mg-doped layer edge. By optimizing both the length of Mg-doped layer, Lm, and the doping concentration, a 5.5 times and 3 times the reduction in the peak electric field near the drain side gate edge is observed as compared with those of the HEMTs with source-connected field plate structure and double field plate structure, respectively. In a device with V GS = −5 V, Lm = 1.5 µm, a peak Mg doping concentration of 8×10 17 cm −3 and a drift region length of 10 µm, the breakdown voltage is observed to increase from 560 V in a conventional device without field plate structure to over 900 V without any area overhead penalty.

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