Highly robust ground moving target detection and relocation method for distributed satellites

The performance of ground moving target detection for distributed satellites will be affected significantly when there is an image registration error, clutter decorrelation and array error. In this paper, a new approach to moving target detection and relocation is proposed based on multi-channel and multi-pixel adaptive signal processing in an image domain. First, multichannel and multi-pixel joint data are equated to a simple array model. Given that there is an image registration error, the real steering vector of the moving target can be estimated through a space projection approach. The optimal beam forming approach is used to cancel clutter, and at the same time the cross-track velocity of the moving target can be determined by searching for the peak value of the cost function. The moving target can then be relocated on the SAR image. The simulation results indicate that this method has a good robustness to image registration error, clutter decorrelation and array error. The detection performance and the estimation accuracy are significantly improved. __________ Translated from Acta Electronica Sinica, 2007, 35(6): 1009–1014 [译自: 电子学报]     

热模锻压力机封高调节指示装置研究

对热模锻压力机封闭高度调节原理及调节指示方式进行研究,为热模锻压力机封闭高度调节指示装置的生产制造提供理论依据,并在实践中得到广泛应用。     

Fabrication of Ultra-Durable and Flexible NiPx-Based Electrode toward High-Efficient Alkaline Seawater Splitting at Industrial Grade Current Density

Designing nonprecious metal-based electrocatalysts to yield sustainable hydrogen energy by large-scale seawater electrolysis is challenging to global emissions of carbon neutrality and carbon peaking. Herein, a series of highly efficient, economical, and robust Ni–P-based nanoballs grown on the flexible and anti-corrosive hydrophobic asbestos (NiP_x@HA) is synthesized by electroless plating at 25 °C toward alkaline simulated seawater splitting. On the basis of the strong chemical attachment between 2D layered substrate and nickel-rich components, robust hexagonal Ni₅P₄ crystalline modification, and fast electron transfer capability, the overpotentials during hydrogen/oxygen evolution reaction (HER/OER) are 208 and 392 mV at 200 mA cm⁻², and the chronopotentiometric measurement at 500 mA cm⁻² lasts for over 40 days. Additionally, the versatile strategy is broadly profitable for industrial applications and enables multi-elemental doping (iron/cobalt/molybdenum/boron/tungsten), flexible substrate employment (nickel foam/filter paper/hydrophilic cloth), and scalable synthesis (22 cm × 22 cm). Density functional theory (DFT) also reveals that the optimized performance is due to the fundamental effect of incorporating O-source into Ni₅P₄. Therefore, this work exhibits a complementary strategy in the construction of NiP_x-based electrodes and offers bright opportunities to produce scalable hydrogen effectively and stably in alkaline corrosive electrolytes.     

Defect and Interface Engineered Tungsten Bronze Superstructure Anode toward Advanced Sodium Storage

Defect and interface engineering, which can facilitate exceptional electrochemical stability and activity, are some of the most important strategies in devising electrode materials. However, the complex nanoscale chemistry and structure characteristics make the origin of electrochemical mechanism extremely difficult to understand. To eliminate this issue, the delicately designed 1D tungsten bronze superstructure anode, guided by defect and interface engineering, is successfully prepared for sodium storage to gain insight into the endogenous structure-property relationships. It can realize the intensely enhanced Na⁺-storage performance with a safe operating potential of ≈0.5 V, a high specific capacity of 228 mAh g⁻¹ at 0.1 C and superior rate performance, which is attributed to the rapid electron and ion transfer process induced by abundant heterointerfaces. More importantly, it can convey an ultra-stable long-term cycling performance, with the capacity retention close to 90% after 4500 cycles at 5 C and 10000 cycles at 10 C, which can be explained by the inherently zero-strain characteristic of a novel vacancy-ordered superstructure in tungsten bronze Ba_3.4Nb₁₀O_28.4 (BNO). This study reveals the structural origins of defect and interface engineering responsible for electrochemical mechanism, providing critical insight into the design of superior electrode materials.     

电阻钎焊次数对牵引电机定子并头钎焊质量的影响

针对某型机车牵引电机定子吊挂部位钎焊并头热影响区烧损情况,进行软铜扁线搭接接头电阻钎焊拉力试验、金相晶粒度级数测定和热影响区导电性能降低机理分析,结果表明随着返焊次数的增加,靠近搭接钎缝根部的母材热影响区力学性能依次下降,晶粒尺寸依次增大。返焊两次时靠近搭接钎缝根部处晶粒度级数达到可接受的极限晶粒度5级,距钎缝8 mm处母材晶粒度级数无明显变化,钎焊接头热影响区局部导电性能降低。     

Interfacial Microenvironment Modulation Boosts Efficient Hydrogen Evolution Reaction in Neutral and Alkaline

The design of highly efficient and stable electrocatalysts in hydrogen evolution reaction over a wide range of pH, especially in neutral or alkaline conditions, is of great significance but remains· challenging. Herein, a family of single-atoms and clusters inside the N-doped porous carbon matrix (NDPCM) are encapsulated. Specifically, the single-atom platinum (Pt_SA) and cluster platinum (Pt_C) in NDPCM exhibited ultralow overpotentials of 20 and 14 mV at −10 mA cm⁻² under neutral and alkaline conditions, respectively and superior long-term durability. Theoretical calculations and operando Raman measurements revealed that the coexistence of Pt_SA and Pt_C can provide multiple H adsorption sites, contributing to the extremely low |ΔG_H*| of H adsorption and constructing a local acidic microenvironment to trigger a unique H₃O⁺-induced water reduction in neutral and alkaline conditions This unique configuration significantly promotes the catalytic activity and opens a new avenue for the crafted design of electrocatalysts.