惯性组合导航系统中基于BRISK的快速景象匹配算法

针对景象匹配/惯性组合导航系统对景象匹配算法精确性、实时性和鲁棒性的要求,提出惯性组合导航用基于二进制鲁棒不变尺度关键点(BRISK)特征描述符的高精度快速景象匹配算法。首先,结合惯性导航的误差特性设置BRISK特征检测子及描述子参数,提取参考图和实测图的BRISK特征和描述符;然后,根据最近邻汉明距离准则获取匹配的BRISK特征点对;最后,利用RANSAC方法和最小二乘算法(LSA),求得位置和航向参数。实验结果表明,本算法具备亚pixel级精度、ms级实时性以及优越的抗噪声、抗光照变化和抗旋转尺度变换能力。     

Optimal Clustering of Hierarchical Hyper-Ring Multicomputers

The Hyper-Ring (HR) is presented as a hierarchical and scalable ring-based topology for small-scale to massively parallel systems which eliminates the major disadvantages of large-scale rings. With a fixed node degree, a low cost, symmetric properties, and a simple routing scheme, the HR topology is very suitable for small-scale to large-scale multicomputer systems. Assuming pipelined communication, the performance of 4- and 5-dimensional HR multicomputers is modeled, the performance model is evaluated, and the results of the performance model evaluation are analyzed. Moreover, the impact of the traffic load and message length on the system performance is analyzed. The major objective of this work is to shed light on how to cluster HRs in order to optimize the system efficiency. Assuming a uniform message arrival rate into the nodes of the HR, the results show that the efficiency of HR topologies with an equal number of nodes is best when the topologies are perfectly balanced. The next best-performing HRs are those with larger rings at the lower (outer) levels and smaller rings at the higher levels (near the root ring). The results confirm that the HR topology is suitable for massively parallel and scalable multicomputer systems as well as for networks of workstations.     

Regulating the Band Structure of Ni Active Sites in Few-Layered Nife-LDH by In Situ Adsorbed Borate for Ampere-Level Oxygen Evolution

Realizing rapid transformation of hydroxide to high-active oxyhydroxide species in layered double hydroxide (LDH) catalyst plays a significant role in enhancing its activity toward oxygen evolution reaction (OER) for hydrogen production from water. Here, a scalable strategy is developed to synthesize defect-rich few-layered NiFe-LDH nanosheets (f-NiFe-LDH-B) with in situ borate modified for boosted and stable OER due to that the borate can narrow the bandgap for Ni sites to realize a more conductive electronic structure. Besides, the adsorbed borate can tune the d band center of Ni sites to promote of hydroxide transformation and facilitate the adsorption of the OER intermediates. The f-NiFe-LDH-B catalyst, therefore, requires only 209 and 249 mV overpotential to deliver 10 and 100 mA cm⁻² OER, respectively, with a Tafel slope of 43.5 mV dec⁻¹. Moreover, only 1.8 V cell voltage is required to reach Ampere-level overall water splitting for 500 h at room temperature.     

Cracked Film Lithography with CuGaOx Buffers for Bifacial CdTe Photovoltaics

Bifacial CdTe solar cells with greater power density than the monofacial baselines are demonstrated by using a CuGaO_x rear interface buffer that passivates while reducing sheet resistance and contact resistance. Inserting CuGaO_x between the CdTe and Au increases mean power density from 18.0 ± 0.5 to 19.8 ± 0.4 mW cm⁻² for one sun front illumination. However, coupling CuGaO_x with a transparent conductive oxide leads to an electrical barrier. Instead, CuGaO_x is integrated with cracked film lithography (CFL)-patterned metal grids. CFL grid wires are spaced narrowly enough (≈10 µm) to alleviate semiconductor resistance while retaining enough passivation and transmittance for a bifacial power gain: bifacial CuGaO_x/CFL grids generate 19.1 ± 0.6 mW cm⁻² for 1 sun front + 0.08 sun rear illumination and 20.0 ± 0.6 mW cm⁻² at 1 sun front + 0.52 sun rear—the highest reported power density at field albedo conditions for a scaled polycrystalline absorber.     

Scalable Synthesis of Holey Deficient 2D Co/NiO Single-Crystal Nanomeshes via Topological Transformation for Efficient Photocatalytic CO2 Reduction

Preparation of holey, single-crystal, 2D nanomaterials containing in-plane nanosized pores is very appealing for the environment and energy-related applications. Herein, an in situ topological transformation is showcased of 2D layered double hydroxides (LDHs) allows scalable synthesis of holey, single-crystal 2D transition metal oxides (TMOs) nanomesh of ultrathin thickness. As-synthesized 2D Co/NiO-2 nanomesh delivers superior photocatalytic CO₂-syngas conversion efficiency (i.e., V_CO of 32460 µmol h⁻¹ g⁻¹ CO and $V_{{\mathrm{H}}_2}$ of 17840 µmol h⁻¹ g⁻¹ H₂), with V_CO about 7.08 and 2.53 times that of NiO and 2D Co/NiO-1 nanomesh containing larger pore size, respectively. As revealed in high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), the high performance of Co/NiO-2 nanomesh primarily originates from the edge sites of nanopores, which carry more defect structures (e.g., atomic steps or vacancies) than basal plane for CO₂ adsorption, and from its single-crystal structure adept at charge transport. Theoretical calculation shows the topological transformation from 2D hydroxide to holey 2D oxide can be achieved, probably since the trace Co dopant induces a lattice distortion and thus a sharp decrease of the dehydration energy of hydroxide precursor. The findings can advance the design of intriguing holey 2D materials with well-defined geometric and electronic properties.     

Organic-Inorganic Conformal Extending High-Purity Metal Nanosheets for Robust Electrochemical Lithium-Ion Storage

2D metal nanosheets present potential applications in catalysis, surface-enhanced Raman scattering, nonlinear optics, energy conversion, and storage due to their extraordinary surface chemistry and quantum-size effects. However, the massive preparation of 2D metal nanosheets with high purity remains challenging. Herein, a scalable and highly efficient approach that relies on organic-inorganic conformal extending procedures to prepare high-purity 2D metal nanosheets (e.g., Sn and Al) with thicknesses of one to a few nanometers is developed. This approach not only results in metal nanosheets with a very uniform and controllable thickness but also effectively avoids the introduction of impurities of other metals and oxides. As a result, this strategy enables scalable preparation of 2D ultrathin metal nanosheets with thicknesses of 1–3 nm. As a proof-of-the-concept application, a compact hybrid anode is constructed from a 2D stacked combination of Sn nanosheets and 2D graphene oxide (SnNS-GO), which show a high reversible capacity of ≈940 mAh g⁻¹ and excellent cycling stability of 1200 cycles without capacity decay. It is believed that this scalable and facile preparation methodology will facilitate the fundamental research and applications of 2D metal nanosheets in important fields, such as electrochemical energy storage, catalysis, nonlinear optics, sensors, etc.     

The Memory-Bounded Speedup Model and Its Impacts in Computing

Journal of Computer Science and Technology - With the surge of big data applications and the worsening of the memory-wall problem, the memory system, instead of the computing unit, becomes the...     

含席夫碱结构碳点缓蚀剂的简易可扩展制备及性能研究

目的 克服目前制备碳点(Carbon dots, CDs)缓蚀剂存在的耗时、耗能等缺点，在室温下一步制备含席夫碱结构的CDs缓蚀剂，并研究其对Q235碳钢的缓蚀性能。方法 设计了一种简易、可扩展的制备方法，以邻苯二胺和对苯醌为前驱体，无需高温加热便可在室温下反应2 h，从而获得含席夫碱结构的CDs。利用TEM等方法对其结构进行表征，并采用UV和PL光谱评估其在HCl溶液中的长期分散稳定性。通过失重法、电化学测试方法研究了不同浓度CDs对Q235碳钢在1 mol/L HCl溶中的缓蚀性能。通过SEM和三维轮廓测量仪分析腐蚀后碳钢表面形貌及化学组成，提出CDs的缓蚀机理。结果 CDs含C=N键，具有多种含氧、含氮基团，有利于其在钢表面的吸附。CDs在HCl溶液中具有长期分散稳定性。当添加浓度为200 mg/L时，其对碳钢在1 mol/L HCl溶液中的缓蚀效率可达到95.05%。CDs为混合型缓蚀剂，能够同时抑制阴极和阳极反应。CDs在碳钢表面的吸附方式遵循Langmuir等温吸附模型，其缓蚀机理为通过物理和化学吸附方式在碳钢表面形成一层保护膜，从而抑制碳钢的腐蚀。结论 成功为CDs缓蚀剂的合成提供了一种简易、可扩展、高效、省时的方法，而且证明了具有席夫碱结构的CDs对碳钢在1 mol/L HCl溶液中的腐蚀具有显著的抑制能力。