Place recognition: An Overview of Vision Perspective

Place recognition is one of the most fundamental topics in computer vision and robotics communities, where the task is to accurately and efficiently recognize the location of a given query image. Despite years of wisdom accumulated in this field, place recognition still remains an open problem due to the various ways in which the appearance of real-world places may differ. This paper presents an overview of the place recognition literature. Since condition invariant and viewpoint invariant features are essential factors to long-term robust visual place recognition system, We start with traditional image description methodology developed in the past, which exploit techniques from image retrieval field. Recently, the rapid advances of related fields such as object detection and image classification have inspired a new technique to improve visual place recognition system, i.e., convolutional neural networks (CNNs). Thus we then introduce recent progress of visual place recognition system based on CNNs to automatically learn better image representations for places. Eventually, we close with discussions and future work of place recognition.Comment: Applied Sciences (2018

Iron-boron pair dissociation in silicon under strong illumination

The dissociation of iron-boron pairs (FeB) in Czochralski silicon under strong illumination was investigated. It is found that the dissociation process shows a double exponential dependence on time. The first fast process is suggested to be caused by a positive Fe in FeB capturing two electrons and diffusion triggered by the electron-phonon interactions, while the second slow one would involve the capturing of one electron followed by temperature dependent dissociation with an activation energy of (0.21 +/- 0.03) eV. The results are important for understanding and controlling the behavior of FeB in concentrator solar cells

Development and Application of Chemical EOR Technologies in China Offshore Oil Fields

At present, polymer flooding as the most effective chemical EOR technique is widely used in onshore oil fields in the world. Also, it has been successfully applied in China offshore oil fields as a major EOR technology. CNOOC has preliminarily established a chemical flooding (polymer, polymer-surfactant, weak gel, etc.) technology system including high-efficiency chemical flooding agents, platform injection facilities, and produced liquid treatment technology. Since 2003, pilot tests and field applications were carried out in S, L, and JW oil fields, and predicted oil increment and good economic benefits have been achieved, which proved that offshore chemical EOR technology is feasible and economical. It has explored a new road for increasing the recovery of offshore oil fields and provided a solid technical guarantee for their economic and efficient development

The Eco-design and Green Manufacturing of a Refrigerator

AbstractThe paper introduces the Energy-related Products(ErP)directive and its late evolution. Both the general and the particular eco-design requirements of a refrigerator are presented. The criteria of standby/off are listed as well. The assumptions made for the modeling of the product and source of the database are put forward. There are 11 factors of environmental impacts used in the evaluation software EIME. The environmental impact of manufacturing, distribution, use and the end of life is analyzed according to a certain refrigerator. The results show that three factors are significant, which are electricity consumed by the refrigerator in the use stage, the raw materials of metal and plastics in the manufacturing. The solution to these problems is provided. The introduction of eco-design to development phase of a product is urgent nowadays

Delayed Ettringite Formation in Fly Ash Concrete under Moist Curing Conditions

During the hydration of cement, tricalcium aluminate (C3A) reacts with gypsum and forms ettringite (AFt). Once all gypsum is consumed, ettringite can further react with remaining C3A and form monosulfate (AFm) at 1–2 days. Normally, at early ages, ettringite all transfers to AFm phase. After several months or years, ettringite can form again if a new source of sulfate becomes available in the pore solution of the paste, viz. delayed ettringite formation. In previous study, it was found that delayed ettringite forms in Portland cement concrete when the concrete samples were cured under moist conditions, i.e., without external sulfate phase. This delayed ettringite formation may result in the decrease of resistance of Portland cement concrete to chloride penetration. After that, it was found that ettringite, viz. delayed ettringite formation, also generated in fly ash concrete. The formation of ettringite, however, has no obvious influence on the resistance of fly ash concrete to chloride penetration

Analysis and Design of the Reconfiguration Motion Qualities of a Deformable Robot Based on a Metamorphic Mechanism

Traditional wheel-legged ground mobile robots can only partially deform during wheel-leg switching, resulting in failure to achieve better environmental adaptability. Metamorphic mechanisms can be introduced into car structure designs. A new type of wheel-legged ground mobile robot, namely a deformable robot, is proposed in this study. Compared with traditional wheel-legged ground mobile robots, the deformable robot is capable of global reconfiguration, that is, when transitioning between the wheeled type (vehicle state) and the legged type (humanoid state), the shape, structure, degrees of freedom, and position of the centre of mass will change significantly. First, based on the characteristics of the wheel-legged compound motion, a structural model of the deformable robot was proposed and designed, and its reconfiguration motion was planned. Then, a kinematic model of the coupled reconfiguration process of the deformable robot was established. A horizontal lifting model was created to keep the front body level when lifting. The motion law of each active joint angle over time was designed based on the requirements of the reconfiguration motion smoothness. The criterion of reconfiguration stability was established and measures to improve it were proposed. Finally, based on the simulation verification of the smoothness, horizontality, and stability of the coupled reconfiguration of the system, a prototype of the deformable robot was developed, and a coupled reconfiguration experiment was conducted on an actual road surface. The experiment results show that the reconfiguration motion of the deformable robot between the vehicle state and the humanoid state had good motion qualities

Quantitative analysis of turbostratically disordered nontronite with a supercell model calibrated by the PONKCS method

Two calibration-based quantitative X-ray diffraction (XRD) models for turbostratically disordered Bulong nontronite, the PONKCS (partial or no known crystal structure) approach and the supercell structural model, were compared in terms of the accuracy and refinement error from Rietveld quantitative phase analysis. The PONKCS approach achieved improved nontronite quantitative results with synchrotron diffraction patterns compared with those achieved with laboratory XRD data as a result of better data quality and the use of Debye–Scherrer geometry with significantly reduced preferred orientation effects. The introduction of a peak shape modifier (spherical harmonics) to correct the quantification result is mainly useful for laboratory XRD patterns containing nontronite collected from Bragg–Brentano geometrywith appreciable preferred orientation effects. A novel calibration approach for the nontronite supercell model was developed, based on the Rietveld quantitative formula in the TOPAS symbolic computation system. The calibrated supercell model achieved better accuracy (deviation within 1 wt%) and lower refinement error than the PONKCS approach because the physically based description of turbostratic disorder requires fewer refinable parameters than the PONKCS approach. The drawbacks and limitations of the supercell approach are also discussed