Experimental Research on Shipborne SINS Rapid Mooring Alignment with Variance-Constraint Kalman Filter and GNSS Position Updates.

Analytical coarse alignment and Kalman filter fine alignment based on zero-velocity are typically used to obtain initial attitude for inertial navigation systems (SINS) on a static base. However, in the shipboard mooring state, the static observation condition is corrupted. This paper presents a rapid alignment method for SINS on swaying bases. The proposed method begins with a coarse alignment technique in the inertial frame to obtain an initial rough attitude. Subsequently, a Kalman filter with position updates is employed to estimate the remaining misalignment error. To enhance the filter estimation performance, an appropriate lower boundary is set to the target states' variances according to a carefully designed relative convergence index. The variance-constraint Kalman filter (VCKF) approach is proposed in this paper, and the shipborne experiments validate its effectiveness. The results demonstrate that the VCKF approach significantly reduces the time requirement for fine alignment to achieve the same accuracy on a swaying base, from 90 min in the classic Kalman filter to 30 min. Additionally, the parameter estimation performance in the Kalman filter is also improved, particularly in situations where unpredicted external interference is involved during fine alignment.

Evolving tides aggravate nuisance flooding along the U.S. coastline.

Nuisance flooding (NF) is defined as minor, nondestructive flooding that causes substantial, accumulating socioeconomic impacts to coastal communities. While sea-level rise is the main driver for the observed increase in NF events in the United States, we show here that secular changes in tides also contribute. An analysis of 40 tidal gauge records from U.S. coasts finds that, at 18 locations, NF increased due to tidal amplification, while decreases in tidal range suppressed NF at 11 locations. Estuaries show the largest changes in NF attributable to tide changes, and these can often be traced to anthropogenic alterations. Limited long-term measurements from estuaries suggest that the effects of evolving tides are more widespread than the locations considered here. The total number of NF days caused by tidal changes has increased at an exponential rate since 1950, adding ~27% to the total number of NF events observed in 2019 across locations with tidal amplification.

Fiber-Shape Na3V2(PO4)2F3@N-Doped Carbon as a Cathode Material with Enhanced Cycling Stability for Na-Ion Batteries.

To overcome intrinsic low electronic conductance, delicately designed fiber-shape Na3V2(PO4)2F3@N-doped carbon composites (NVPF@C) have been prepared for boosting Na-storage performance. This distinctive interlinked three-dimensional network structure can effectively facilitate electron/Na-ion transportation by decreasing the NVPF particle size to shorten the ionic diffusion paths and introducing a conducting N-doping carbon scaffold to improve electronic conductivity. Benefiting from the favorable structural design and fascinating reaction kinetics, the modified NVPF@C material demonstrates superior sodium-storage performance with 109.5 mAh g-1 high reversible capacity at a moderate current of 0.1 C, excellent rate tolerance of 78.9 mAh g-1 at a high rate of 30 C, and gratifying long-term cyclability (87.8% capacity retention after 1000 cycles at 20 C; 83.4% capacity retention after 1500 round trips at a ultrahigh rate of 50 C). The fascinating electrochemical performance remains stable when NVPF@C was examined as the cathode material for a full cell, suggesting the fiber-shape NVPF@C as one of the most promising applicable materials for sodium-ion batteries. Moreover, the approach of the three-dimensional conductive network by electrospinning is proposed as a strategy of efficiency and promising prospect to enhance the electrochemical property of other materials for sodium-ion batteries.

Fabrication of SnS2/Mn2SnS4/Carbon Heterostructures for Sodium-Ion Batteries with High Initial Coulombic Efficiency and Cycling Stability.

SnS2 has been extensive studied as an anode material for sodium storage owing to its high theoretical specific capacity, whereas the unsatisfied initial Coulombic efficiency (ICE) caused by the partial irreversible conversion reaction during the charge/discharge process is one of the critical issues that hamper its practical applications. Hence, heterostructured SnS2/Mn2SnS4/carbon nanoboxes (SMS/C NBs) have been developed by a facial wet-chemical method and utilized as the anode material of sodium ion batteries. SMS/C NBs can deliver an initial capacity of 841.2 mAh g-1 with high ICE of 90.8%, excellent rate capability (752.3, 604.7, 570.1, 546.9, 519.7, and 488.7 mAh g-1 at the current rate of 0.1, 0.5, 1.0, 2.0, 5.0, and 10.0 A g-1, respectively), and long cycling stability (522.5 mAh g-1 at 5.0 A g-1 after 500 cycles). The existence of SnS2/Mn2SnS4 heterojunctions can effectively stabilize the reaction products Sn and Na2S, greatly prevent the coarsening of nanosized Sn0, and enhance reversible conversion--alloying reaction, which play a key role in improving the ICE and extending the cycling performance. Moreover, the heterostructured SMS coupled with the interacting carbon network provides efficient channels for electrons and Na+ diffusion, resulting in an excellent rate performance.

Exploration of VPO4 as a new anode material for sodium-ion batteries.

Carbon-coated VPO4 nanoparticles embedded into a porous carbon matrix were synthesized via a facile sol-gel approach and investigated as a novel polyanion anode material for sodium-ion batteries. The VPO4@carbon anode demonstrates excellent rate capability and superior cyclic stability (245.3 mA h g-1 at 1000 mA g-1 after 200 cycles).

Surface Modification of Na3V2(PO4)3 by Nitrogen and Sulfur Dual-Doped Carbon Layer with Advanced Sodium Storage Property.

Nitrogen and sulfur dual-doped carbon layer wrapped Na3V2(PO4)3 nanoparticles (NVP@NSC) have been successfully fabricated by the facile solid-state method. In this hierarchical structure, the Na3V2(PO4)3 nanoparticles are well dispersed and closely coated by nitrogen and sulfur dual-doped carbon layer, constructing an effective and interconnected conducting network to reduce the internal resistance. Furthermore, the uniform coating layers alleviate the agglomeration of Na3V2(PO4)3 as well as mitigate the side reaction between electrode and electrolyte. Because of the excellent electron transfer mutually enhancing sodium diffusion for this extraordinary structure, the NVP@NSC composite delivers an impressive discharge capacity of 113.0 mAh g-1 at 1 C and shows a capacity retention of 82.1% after 5000 cycles at an ultrahigh rate of 50 C, suggesting the remarkable rate capability and long cyclicity. Surprisingly, a reversible capacity of 91.1 mAh g-1 is maintained after 1000 cycles at 5 C under the elevated temperature of 55 °C. The approach of nitrogen and sulfur dual-doped carbon-coated Na3V2(PO4)3 provides an effective and promising strategy to enhance the ultrahigh rate and ultralong life property of cathode, which can be used for large-scale commercial production in sodium ion batteries.