Learning a Deep Predictive Coding Network for a Semi-Supervised 3D-Hand Pose Estimation

In this paper we present a CNN based approach for a real time 3D-hand pose estimation from the depth sequence. Prior discriminative approaches have achieved remarkable success but are facing two main challenges: Firstly, the methods are fully supervised hence require large numbers of annotated training data to extract the dynamic information from a hand representation. Secondly, unreliable hand detectors based on strong assumptions or a weak detector which often fail in several situations like complex environment and multiple hands. In contrast to these methods, this paper presents an approach that can be considered as semi-supervised by performing predictive coding of image sequences of hand poses in order to capture latent features underlying a given image without supervision. The hand is modelled using a novel latent tree dependency model (LDTM) which transforms internal joint location to an explicit representation. Then the modeled hand topology is integrated with the pose estimator using data dependent method to jointly learn latent variables of the posterior pose appearance and the pose configuration respectively. Finally, an unsupervised error term which is a part of the recurrent architecture ensures smooth estimations of the final pose. Experiments on three challenging public datasets, ICVL, MSRA, and NYU demonstrate the significant performance of the proposed method which is comparable or better than state-of-the-art approaches.      

高碾压混凝土重力坝分区材料-结构界面特性与变形协调仿真分析

高碾压混凝土重力坝不同功能部位"结构特性"与"材料性能"的差异产生的变形协调问题直接关系到工程结构的安全运行,现阶段变形协调分析多是对结构变形和受力进行分析,对异种材料变形协调机理认识不足,缺乏理论基础研究。本文基于界面力学理论,考虑混凝土坝分区中常见的两种双材料界面形式与理想界面的连续边界条件,基于奇异性特征值的特征方程,提出了以应力奇异性特征值作为异种材料变形协调的评价指标,并通过有限元分析验证了理论计算的正确性与有效性;进而分析了界面结合角度和异种材料组合对单侧自由界面端与埋入界面折点处应力奇异性的影响,通过非均质有限元数值仿真分析了复合试件破坏模式,研究了抗压强度与应力奇异性特征值的关系;最后通过统计实际混凝土坝工程中不同坝段内的双材料界面的材料参数(弹性模量)与结构参数(界面形式与结合角度),计算奇异性特征值,评价了该工程中界面的变形协调特性,为高混凝土坝分区材料-结构设计与材料选取提供新的思路。     

工艺参数对6061-T6铝合金真空扩散焊接接头形貌和性能的影响

在不同工艺参数下对化学清洗去除表面氧化膜的6061-T6铝合金进行真空扩散焊接,研究了焊接温度(500~560℃)、焊接压力(1.0~5.0MPa)和保温时间(0.5~3h)对焊接接头界面形貌和剪切强度的影响,得到了优化工艺参数。结果表明:随着焊接温度的升高、焊接压力的增大和保温时间的延长,接头焊缝变窄并最终消失,剪切强度和焊合率增大;但当保温时间延长到3h时,焊缝附近晶粒发生粗化,导致剪切强度降低,且接头发生较大变形;不同工艺参数下接头的剪切断裂形式均为脆性断裂;较优的真空扩散焊接工艺参数为焊接温度540℃、保温时间2h、焊接压力4.0MPa。     

Rice spike-like g-C3N4/TiO2 heterojunctions with tight-binding interface by using sodium titanate ultralong nanotube as precursor and template

A novel rice spike-like g-C₃N₄/TiO₂ nanowire heterojunctions are fabricated by hydrothermal treating Na₂Ti₃O₇ ultralong nanotubes in the presence of g-C₃N₄. The presence of g-C₃N₄ promotes the hydrolysis of Na₂Ti₃O₇ ultralong nanotubes. The partially replaced O of TiO₂ by N from g-C₃N₄ leads to the formation of a tight-binding interface between one dimensional TiO₂ and two dimensional g-C₃N₄, which is crucial for fast and effective transfer of photogenerated electrons in heterostructured photocatalysts. As a result, the g-C₃N₄/TiO₂ nanowire heterojunctions exhibit excellent visible-light photocatalytic activity. The kinetic constant (k) of g-C₃N₄/TiO₂ (0.024?min^?1) for degradation of methylene blue under visible light irradiation is 1.85 and 4 times than that of pure g-C₃N₄ and P25, respectively.     

An indirect testing approach for characterizing pressure profiles of compression bandages and hosiery

As outlined in compression therapy literature, the performance of a compression textile can be characterized by its stiffness and interface pressure. In this study, an indirect approach for measuring pressure from a set of compression bandages and hosiery was developed, from which rigidity (EI) values were determined, and tension–elongation curves and pressure-elongation data were calculated. The calculated pressure values were compared against PicoPress sensor readings measured on 10 participants. Results showed that the correlation between both approaches varied among bandage and hosiery samples.     

GO@TA-Fe/PVDF纳米复合材料制备与介电性能

为降低氧化石墨烯（GO）/聚偏氟乙烯（PVDF）体系的介电损耗，本文采用单宁酸-铁配合物（TA-Fe）修饰GO表面，将改性GO和PVDF复合后制得了GO@TA-Fe/PVDF纳米复合电介质材料，研究了GO@TA-Fe对PVDF复合材料的微观形貌及介电性能影响。研究结果表明，TA-Fe包覆层强化了GO与PVDF基体间界面相容性及界面作用力，促进了GO在基体中均匀分散；TA-Fe界面层的存在显著降低了GO/PVDF漏导电流及损耗，归因于绝缘界面层有效阻止了GO之间直接接触，抑制漏导电流；TA-Fe用量对体系介电性能有明显影响，随TA-Fe用量增大，体系的介电损耗和电导率显著降低。与GO/PVDF相比，质量分数2%的GO@TA-Fe/PVDF在100Hz下介电常数为1000，而介电损耗由19.8降低为0.08。本研究制备的高介电常数及低损耗的柔性GO@TA-Fe/PVDF纳米电介质材料在电子器件及电力设备领域具有潜在应用。     

Achieving Rich and Active Alkaline Hydrogen Evolution Heterostructures via Interface Engineering on 2D 1T‐MoS2 Quantum Sheets

Large‐scale production of hydrogen from water‐alkali electrolyzers is impeded by the sluggish kinetics of hydrogen evolution reaction (HER) electrocatalysts. The hybridization of an acid‐active HER catalyst with a cocatalyst at the nanoscale helps boost HER kinetics in alkaline media. Here, it is demonstrated that 1T–MoS₂ nanosheet edges (instead of basal planes) decorated by metal hydroxides form highly active ${\text{edge}}_{{\text{1T‐MoS}}_{\text{2}}}$/ ${\text{edge}}_{\text{Ni}{(\text{OH})}_{\text{2}}}$ heterostructures, which significantly enhance HER performance in alkaline media. Featured with rich ${\text{edge}}_{{\text{1T‐MoS}}_{\text{2}}}$/ ${\text{edge}}_{\text{Ni}{(\text{OH})}_{\text{2}}}$ sites, the fabricated 1T–MoS₂ QS/Ni(OH)₂ hybrid (quantum sized 1T–MoS₂ sheets decorated with Ni(OH)₂ via interface engineering) only requires overpotentials of 57 and 112 mV to drive HER current densities of 10 and 100 mA cm^?2, respectively, and has a low Tafel slope of 30 mV dec^?1 in 1 m KOH. So far, this is the best performance for MoS₂‐based electrocatalysts and the 1T–MoS₂ QS/Ni(OH)₂ hybrid is among the best‐performing non‐Pt alkaline HER electrocatalysts known. The HER process is durable for 100 h at current densities up to 500 mA cm^?2. This work not only provides an active, cost‐effective, and robust alkaline HER electrocatalyst, but also demonstrates a design strategy for preparing high‐performance catalysts based on edge‐rich 2D quantum sheets for other catalytic reactions.     

Surface energy and separation mechanics of droplet interface phospholipid bilayers

Droplet interface bilayers are a convenient model system to study the physio-chemical properties of phospholipid bilayers, the major component of the cell membrane. The mechanical response of these bilayers to various external mechanical stimuli is an active area of research because of its implications for cellular viability and the development of artificial cells. In this article, we characterize the separation mechanics of droplet interface bilayers under step strain using a combination of experiments and numerical modelling. Initially, we show that the bilayer surface energy can be obtained using principles of energy conservation. Subsequently, we subject the system to a step strain by separating the drops in a step-wise manner, and track the evolution of the bilayer contact angle and radius. The relaxation time of the bilayer contact angle and radius along with the decay magnitude of the bilayer radius were observed to increase with each separation step. By analysing the forces acting on the bilayer and the rate of separation, we show that the bilayer separates primarily through the peeling process with the dominant resistance to separation coming from viscous dissipation associated with corner flows. Finally, we explain the intrinsic features of the observed bilayer separation by means of a mathematical model comprising the Young–Laplace equation and an evolution equation. We believe that the reported experimental and numerical results extend the scientific understanding of lipid bilayer mechanics, and that the developed experimental and numerical tools offer a convenient platform to study the mechanics of other types of bilayers.     

Gluten–starch interface characteristics and wheat dough rheology—Insights from hybrid artificial systems

Referring to the total surface existing in wheat dough, gluten–starch interfaces are a major component. However, their impact on dough rheology is largely unclear. Common viewpoints, based on starch surface modifications or reconstitution experiments, failed to show unambiguous relations of interface characteristics and dough rheology. Observing hybrid artificial dough systems with defined particle surface functionalization gives a new perspective. Since surface functionalization standardizes particle–polymer interfaces, the impact on rheology becomes clearly transferable and thus, contributes to a better understanding of gluten–starch interfaces. Based on this perspective, the effect of particle/starch surface functionality is discussed in relation to the rheological properties of natural wheat dough and modified gluten–starch systems. A competitive relation of starch and gluten for intermolecular interactions with the network-forming polymer becomes apparent during network development by adsorption phenomena. This gluten–starch adhesiveness delays the beginning of non-linearity under large deformations, thus contributing to a high deformability of dough. Consequently, starch surface functionality affects the mechanical properties, starting from network formation and ending with the thermal fixation of structure.