In recent years, estimating the 6D pose of object instances with convolutional neural network (CNN) has received considerable attention. Depending on whether intermediate cues are used, the relevant literature can be roughly divided into two broad categories: direct methods and two-stage pipelines. For the latter, intermediate cues, such as 3D object coordinates, semantic keypoints, or virtual control points instead of pose parameters are regressed by CNN in the first stage. Object pose can then be solved by correspondence constraints constructed with these intermediate cues. In this paper, we focus on the postprocessing of a two-stage pipeline and propose to combine two learning concepts for estimating object pose under challenging scenes: projection grouping on one side, and correspondence learning on the other. We firstly employ a local-patch based method to predict projection heatmaps which denote the confidence distribution of projection of 3D bounding box’s corners. A projection grouping module is then proposed to remove redundant local maxima from each layer of heatmaps. Instead of directly feeding 2D–3D correspondences to the perspective-n-point (PnP) algorithm, multiple correspondence hypotheses are sampled from local maxima and its corresponding neighborhood and ranked by a correspondence–evaluation network. Finally, correspondences with higher confidence are selected to determine object pose. Extensive experiments on three public datasets demonstrate that the proposed framework outperforms several state of the art methods.
Development of non-noble-metal catalysts for overall water splitting with both excellent activity and robust stability has attracted great attention recently. Herein, we reported a facile one-pot and low-temperature synthesis of a Ni-doped Co3O4 ultrathin nanosheets array on Ni foam via in situ etching of H+ from hydrolysis of cobalt chloride and Ni doping released from Ni foam. The as-prepared Ni–Co3O4 nanosheets\Ni foam as large-sized electrodes possessed the low overpotential of 170 mV to achieve a current density of 10 mA cm–2 with a small Tafel slope of 76.9 mV dec–1 and strong catalytic stability in 1.0 M KOH. Furthermore, the as-prepared electrodes showed an efficient bifunctional catalytic activity for OER in alkaline electrolyte. Ni–Co3O4 nanosheets\Ni foam electrodes were used as both cathode and anode to form a two-electrode alkaline water electrolyzer, which only needed a voltage of 1.643 V to afford a water-splitting current density of 10 mA cm–2 in 1.0 M KOH electrolyte. Dramatically, it also can be light-driven by using polycrystalline silicon solar cells. The proposed strategy herein offered great advantages in terms of simple, low-cost, low-temperature operation and ease of scale-up, which was also a common method for synthesizing Ni-doped metal oxide electrocatalysts.
This paper presents a novel global object descriptor, achieving a balance of descriptiveness, robustness and efficiency. The proposed descriptor forms a comprehensive description of an object instance by encoding projection statistics in terms of contour signature and distribution matrix (CSDM). To generate a CSDM descriptor, a local reference frame is defined to align the object's point cloud with the canonical coordinate system. After that, the sub-histogram of contour signature and distribution matrix can be determined from orthographic 2D projected patterns. Finally, a CSDM descriptor is generated with a concatenation of sub-histogram. In recognition stage, a two-stage comparison metric is designed to eliminate information redundancy. A comprehensive performance evaluation in terms of scalability, descriptiveness, robustness and efficiency is performed on the publicly available dataset. Experimental results show that the performance of CSDM descriptor is comparable with the other two state-of-the-art descriptors.
Conduct of plant research to assess the impact of microgravity on plant growth and development requires a plant growth unit that has the capability to provide totally controlled environment in the plant chamber. Since plants are sensitive to a number of atmospheric gaseous materials, the plant chamber atmosphere must be isolated from the space vehicle atmosphere and the plant growth unit must also be capable of removing any deleterious materials that may impact plant growth and development. Advanced ASTROCULTURE™ (ADVASC), a space-based plant growth unit based on proven ASTROCULTURE™ technology, has been developed by the Wisconsin Center for Space Automation and Robotics (WCSAR) at the University of Wisconsin-Madison to take advantage of plant research opportunities during the early assembly phase of International Space Station (ISS) when ISS resources and up/down mass availability would be very limited. ADVASC provides a completely enclosed, environmentally controlled plant growth chamber to support commercially oriented and/or fundamental plant research for time duration of several months in reduced gravity environment.
Abstract The pioneering exfoliation of monolayer tungsten diselenide has greatly inspired researchers toward semiconducting applications. WSe 2 belongs to a family of transition‐metal dichalcogenides. Similar to graphene, WSe 2 and analogous dichalcogenides have layered structures with weak van der Waals interactions between two adjacent layers. First, the readers are presented with the fundamentals of WSe 2, such as types, morphologies, and properties. Here, we report the characterization principles and practices such as microscopy, spectroscopy, and diffraction. Second, the methods for obtaining high‐quality WSe 2 , such as exfoliation, hydrothermal and chemical vapor deposition, are briefly listed. With advantages of light weight, flexibility, and high quantum efficiency, 2D materials may have a niche in optoelectronics as building blocks in p‐n junctions. Therefore, we introduce a state‐of‐the‐art demonstration of heterostructure devices employing the p‐type WSe 2 semiconductor. The device architectures include field‐effect transistors, photodetectors, gas sensors, and photovoltaic solar cells. Due to its unique electronic, optical, and energy band properties, WSe 2 has been increasingly investigated due to the conductivity of the p‐type charge carrier upon palladium contact. Eventually, the dynamic research on WSe 2 and van der Waals heterostructures is summarized to arouse the passion of the 2D research community. image
Abstract Electrocatalytic water splitting for the production of hydrogen proves to be effective and available. In general, the thermal radiation synthesis usually involves a slow heating and cooling process. Here, a high‐frequency induction heating (IH) is employed to rapidly prepare various self‐supported electrocatalysts grown on Ni foam (NF) in liquid‐ and gas‐phase within 1–3 min. The NF not only serves as an in situ heating medium, but also as a growth substrate. The as‐synthesized Ni nanoparticles anchored on MoO 2 nanowires supported on NF (Ni‐MoO 2 /NF‐IH) enable catalysis of hydrogen evolution reaction (HER), showing a low overpotential of −39 mV (10 mA cm −2 ) and maintaining the stability of 12 h in alkaline condition. Moreover, the NiFe layered double hydroxide (NiFe LDH/NF‐IH) is also synthesized via IH and affords outstanding oxygen evolution reaction (OER) activity with an overpotential of 246 mV (10 mA cm −2 ). The Ni‐MoO 2 /NF‐IH and NiFe LDH/NF‐IH are assembled to construct a two‐electrode system, where a small cell voltage of ≈1.50 V enables a current density of 10 mA cm −2 . More importantly, this IH method is also available to rapidly synthesize other freestanding electrocatalysts on NF, such as transition metal hydroxides and metal nitrides.
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