End-to-end Weakly-supervised Multiple 3D Hand Mesh Reconstruction from Single Image

In this paper, we consider the challenging task of simultaneously locating and recovering multiple hands from single 2D image. Previous studies either focus on single hand reconstruction or solve this problem in a multi-stage way. Moreover, the conventional two-stage pipeline firstly detects hand areas, and then estimates 3D hand pose from each cropped patch. To reduce the computational redundancy in preprocessing and feature extraction, we propose a concise but efficient single-stage pipeline. Specifically, we design a multi-head auto-encoder structure for multi-hand reconstruction, where each head network shares the same feature map and outputs the hand center, pose and texture, respectively. Besides, we adopt a weakly-supervised scheme to alleviate the burden of expensive 3D real-world data annotations. To this end, we propose a series of losses optimized by a stage-wise training scheme, where a multi-hand dataset with 2D annotations is generated based on the publicly available single hand datasets. In order to further improve the accuracy of the weakly supervised model, we adopt several feature consistency constraints in both single and multiple hand settings. Specifically, the keypoints of each hand estimated from local features should be consistent with the re-projected points predicted from global features. Extensive experiments on public benchmarks including FreiHAND, HO3D, InterHand2.6M and RHD demonstrate that our method outperforms the state-of-the-art model-based methods in both weakly-supervised and fully-supervised manners

The Application of Downhole Vibration Factor in Drilling Tool Reliability Big Data Analytics - A Review

In the challenging downhole environment, drilling tools are normally subject to high temperature, severe vibration, and other harsh operation conditions. The drilling activities generate massive field data, namely field reliability big data (FRBD), which includes downhole operation, environment, failure, degradation, and dynamic data. Field reliability big data has large size, high variety, and extreme complexity. FRBD presents abundant opportunities and great challenges for drilling tool reliability analytics. Consequently, as one of the key factors to affect drilling tool reliability, the downhole vibration factor plays an essential role in the reliability analytics based on FRBD. This paper reviews the important parameters of downhole drilling operations, examines the mode, physical and reliability impact of downhole vibration, and presents the features of reliability big data analytics. Specifically, this paper explores the application of vibration factor in reliability big data analytics covering tool lifetime/failure prediction, prognostics/diagnostics, condition monitoring (CM), and maintenance planning and optimization. Furthermore, the authors highlight the future research about how to better apply the downhole vibration factor in reliability big data analytics to further improve tool reliability and optimize maintenance planning

Evidence for critical scaling of plasmonic modes at the percolation threshold in metallic nanostructures

In this work we provide the experimental demonstration of critical scaling of plasmonic resonances in a percolation series of periodic structures which evolve from arrays of holes to arrays of quasi-triangles. Our observations are in agreement with the general percolation theory and could lead to sensor and detector applications

Enhanced broad-band extraordinary optical transmission through subwavelength perforated metallic films on strongly polarizable substrates

We demonstrate through simulations and experiments that a perforated metallic film, with subwavelength perforation dimensions and spacing, deposited on a substrate with a sufficiently large dielectric constant, can develop a broad- band frequency window where the transmittance of light into the substrate becomes essentially equal to that in the film absence. We show that the location of this broad-band extraordinary optical transmission window can be engineered in a wide frequency range (from IR to UV), by varying the geometry and the material of the perforated film as well as the dielectric constant of the substrate. This effect could be useful in the development of transparent conducting electrodes for various photonic and photovoltaic devices

Dissolution of cellulose in ionic liquid–DMSO mixtures : roles of DMSO/IL ratio and the cation alkyl chain length

The dissolution behavior of cellulose in the mixtures of dimethyl sulfoxide (DMSO) and different ionic liquids (ILs) at 25 °C was studied. High solubility of cellulose was reached in the mixtures of ILs and DMSO at mole fractions of 1:2, 1:2, and 1:1 for 1-butyl-3-methylimidazolium acetate, 1-propyl-3-methylimidazolium acetate, and 1-ethyl-3-methylimidazolium acetate, respectively. At high DMSO/IL molar ratios (10:1–2:1), a longer alkyl chain of the IL cation led to higher cellulose solubility. However, shorter cation alkyl chains favored cellulose dissolution at 1:1. Rheological, Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR) measurements were used to understand cellulose dissolution. It was found out that the increase of the DMSO ratio in binary mixtures caused higher cellulose solubility by decreasing the viscosity of systems. For cations with longer alkyl chains, stronger interaction between the IL and cellulose and higher viscosity of DMSO/IL mixtures were observed. The new knowledge obtained here could be useful to the development of cost-effective solvent systems for biopolymers

Applications of ionic liquids in starch chemistry : a review

Recently, the utilization of starch to replace synthetic polymers for the manufacture of green materials has gained extensive interest, due to its renewability, biodegradability, abundance and low cost. On the other hand, ionic liquids (ILs) have been widely recognized as promising “green solvents” to replace volatile organic solvents for polysaccharide processing. Over the past few years, ILs have been increasingly demonstrated to serve as excellent media for the dissolution, plasticization and derivatization of starch. This allows the synthesis of chemically modified starches with high degree of substitution (DS) and the development of various starch-based materials such as thermoplastic starch, composite films, solid polymer electrolytes, nanoparticles and drug carriers. The main objective of this review is to present an overview of the roles of ILs in starch dissolution, gelatinization, modification and plasticization, and their industrial applications. Moreover, this review is intended to provide a comprehensive understanding of the mechanisms behind the IL-processing of starch and to provide insights into the rational development of novel starch-based materials with ILs

Structural disorganization of cereal, tuber and bean starches in aqueous ionic liquid at room temperature : role of starch granule surface structure

The structural disorganization of different starches in a 1-ethyl-3-methylimidazolium acetate ([Emim][OAc])/water mixture (1:6 mol./mol.) at room temperature (25 °C) was studied. For normal cereal starches, which have pinholes randomly dispersed on the granule surface or only in the outermost annular region (wheat starch), the aqueous ionic liquid (IL) completely destroyed the granule structure within 1–1.5 h. Pea starch (PeS) granules with cracks were destroyed by the aqueous IL within 6 h. High-amylose maize starch (HAMS), as well as potato and purple yam starches (PoS and PYS), which have a dense and thick outer granule layer, were even more resistant to the action of the solvent. Structural disorganization was accompanied by increased viscosity and controlled the binding of water molecules with starch chains. From this study, we concluded that the surface characteristics of starch granule are an important factor affecting starch structural disorganization in an aqueous IL