Suction-based Grasp Point Estimation in Cluttered Environment for Robotic Manipulator Using Deep Learning-based Affordance Map

Machine Intelligence Research - Perception and manipulation tasks for robotic manipulators involving highly-cluttered objects have become increasingly in-demand for achieving a more efficient...     

Simulation of silica fume blended cement hydration

A model is proposed in this paper to simulate silica fume (SF) blended cement hydration based on the kinetics, stoichiometry and physical chemistry of cement hydration and pozzolanic reaction. The pozzolanic reaction degree, volume fraction of hydration products, capillary porosity and gel porosity can be obtained from model simulation. By using proper amount of silica fume replacement, the microstructure of silica fume blended cement paste is improved since the volume fraction of C-S-H gel is increased, Ca(OH)₂ content and capillary porosity are decreased due to pozzolanic reaction compared with ordinary Portland cement (OPC) paste. The effects of silica fume particle size, glass phase content and the percentage of silica fume replacement on pozzolanic reaction degree, volume fraction of hydration products, and capillary porosity are simulated. The simulation results show that finer silica fume particles with higher glass phase content (GP) are of higher reactivity. There is an optimum silica fume replacement; extra silica fume only acts as inert filler because there is no enough Ca(OH)₂ from cement hydration to react with it pozzolanically.

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Résumé Le modèle proposé dans cet article simule l'hydratation de ciment mélangé à de la fumée de silice et est basé sur la cinétique, la stoichiométrie et la physico-chimie de l'hydratation du ciment et la réaction pozzolanique. Le degré de réaction pozzolanique, la fraction volumique des produits de l'hydratation, la porosité capillaire et la porosité de gel peuvent être obtenues par un modèle de simulation. En utilisant la bonne quantité de remplacement de fumée de silice, la microstructure de la fumée de silice mélangée à la pate de ciment est améliorée étant donné que la fraction volumique du gel C-S-H augmente, que le taux de Ca(OH)₂ et la porosité capillaire décroissent en raison de la réaction pozzolanique lorsque l'on compare avec une pate de ciment à base de Portland ordinaire (OPC). Les effets de la taille des particules de fumée de silice, le contenu de la phase de verre et le pourcentage de remplacement de fumée de silice sur le degré de réaction pozzolanique, la fraction volumique des produits d'hydratation et la porosité capillaire sont simulés. Les résultats de cette simulation montrent que de plus fines particules de fumée de silice avec une plus grande quantité de phase de verre (GP) sont de forte réactivité. Il existe un remplacement de fumée de silice optimal; de la fumée de silice en plus ne sert que de filler inerte car il n'y a pas assez de Ca(OH)₂ à partir de l'hydratation du ciment pour provoquer une réaction pozzolanique

     

Robust proportional-derivative control on SO(3) with disturbance compensation for quadrotor UAV

International Journal of Control, Automation and Systems - This paper presents a control law that can counter both random disturbance and inertia matrix perturbation in quadrotor attitude...     

An Assistive VLC Technology for Smart Home Devices Using EOG

In recent years, assistive technology has been an emerging area of research to improve the quality of life, especially for the disabled and elderly people. In this paper, a novel electro-oculogram (EOG) signal based assistive visible light communication (VLC) in a smart home environment is presented. The eye movement is captured using silver chloride (AgCl) surface electrodes placed around eyes. The captured signal is further processed and transmitted using a VLC link to control smart home devices. To validate the proposed EOG-VLC based smart device control scheme, experiments were conducted. For the ease of the experiments, instead of an actual smart home device, we employed a digital door lock to verify its accurate control operation. Experiment results demonstrate that the proposed smart device control scheme operates accurately and reliably. Therefore, since the proposed scheme is based on a less hazardous VLC link, it is envisioned that the scheme can pave the way for greener and safer smart homes, particularly benefiting disabled and elderly people.     

CFD–DEM investigation into the scaling up of spout‐fluid beds via two interconnected chambers

The hydrodynamics and chamber interaction in a three‐dimensional spout‐fluid bed with two interconnected chambers are investigated via computational fluid dynamics coupled with discrete element method (CFD–DEM), because multiple interconnected chambers are key to scaling up spout‐fluid beds. The overall solid motion, spouting evolution, and spout‐annulus interface is studied, followed by time‐averaged hydrodynamics, particle‐scale information, spout‐annulus interaction, and inter‐chamber interaction. The results show that inter‐chamber interactions lead to unique characteristics distinct from that for a single‐chamber system, including (1) asymmetry of the hydrodynamics within each chamber, (2) alternative spouting behavior in the two chambers, (3) smaller pressure drop in terms of magnitude and fluctuations, (4) two peaks in the solid residence time (SRT) frequency histogram of the annulus, (5) average SRT in the spout is twice that in a single‐chamber, and (6) larger solid dispersion in all three directions. The results provide meaningful understanding for the scale‐up of spout‐fluid beds. © 2016 American Institute of Chemical Engineers AIChE J, 62: 1898–1916, 2016     

DEM study of granular flow characteristics in the active and passive regions of a three‐dimensional rotating drum

Three‐dimensional modeling of the solid motion in a lab‐scale rotating drum has been conducted via the discrete element method. After validating the simulated results with available experimental data, the active‐passive interface was identified, following which particle‐scale information in these two regions, in particular the influences of fill level and rotating velocity, were obtained. The results demonstrate that: (1) the total number of particles in the passive region is three times that in the active, (2) the transverse and axial velocities span a wider range in the active region, with the transverse values being greater, (3) the collision force is much higher in the active region, with the greatest magnitudes in the y direction relative to that in the x and z directions, (4) particle displacements are generally lower and have a narrower distribution in the active region, (5) the local solid residence time (SRT) distribution profiles are similar axially in that the highest SRT magnitudes are at the center region of the bed, while the other parts of the bed have uniform SRT magnitudes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3874–3888, 2016     

Fracture toughness of Cu-Sn intermetallic thin films

Intermetallic compounds (IMCs) are formed as a result of interaction between solder and metallization to form joints in electronic packaging. These joints provide mechanical and electrical contacts between components. The knowledge of fracture strength of the IMCs will facilitate predicting the overall joint property, as it is more disposed to failure at the joint compared to the solder because of its brittle characteristics. The salient feature of this paper is the measurement of the fracture toughness and the critical energy-release rate of Cu₃Sn and Cu₆Sn₅ intermetallic thin films, which is the result of the interaction between Sn from the solder and Cu from the metallization. To achieve the objective, a controlled buckling test was used. A buckling test in the current work refers to one that displays large transverse displacement caused by axial compressive loading on a slender beam. The stress and strain along the beam can be easily calculated by the applied displacement. Fracture-toughness values of Cu₃Sn and Cu₆Sn₅ are 2.85 MPa √m ± 0.17 MPa √m and 2.36 MPa √m ± 0.15 MPa √m, respectively. Corresponding critical energy-release rate values are 65.5 J/m² ± 8.0 J/m² and 55.9 J/m² ± 7.3 J/m², respectively. The values obtained were much higher than the ones measured in bulk intermetallic samples but correlated well with those values obtained from conventional fracture-toughness specimens when fracture was confined within the intermetallic layers. Hence, the controlled buckling test is a promising fast and effective way to elucidate mechanical properties of thin films.     

Review on Identity-Based Batch Verification Schemes for Security and Privacy in VANETs

The study of vehicular ad-hoc networks (VANETs) has received significant attention among academia; even so, its security and privacy still become a central issue that is wide-open to discuss. The authentication schemes deployed in VANETs have a substantial impact on its security and privacy. Many researchers have proposed a variety of schemes related to the information verification and efficiency improvement in VANETs. In recent years, many papers have proposed identity-based batch verification (IBV) schemes in regard to diminishing overhead in the message verification process in VANETs. This survey begins with providing background information about VANETs and clarifying its security and privacy, as well as performance requirements that must be satisfied. After presenting an outlook of some relevant surveys of VANETs, a brief review of some IBV schemes published in recent years is conferred. The detailed approach of each scheme, with a comprehensive comparison between them, has been provided afterward. Finally, we summarize those recent studies and possible future improvements.     

Analysis of hydraulic conductivity of fractured groundwater flow media using artificial neural network back propagation

Neural Computing and Applications - Groundwater flow in the Grasberg open-pit mine is governed by fractured flow media. Groundwater modeling in fractured media requires detailed hydraulic...     

Shore-to-Undersea Visible Light Communication

In this paper, a novel visible light based shore-to-undersea (S2US) communication is proposed. It considers various properties of both maritime and undersea environments such as wave height, wind speed, and absorption. A lighthouse transmits the signal using white light emitting diodes (LEDs) and this signal is received by a buoy that acts as a beacon to relay to the undersea receiver. The beacon employs the decode-and-forward (DF) method in such a way that green LEDs transmit the DF processed signal to the undersea receivers via the undersea optical channel. The performance of the proposed S2US system was first evaluated via simulations with the JONSWAP spectrum model representing the maritime optical channel and the Jerlov water type representing the undersea optical channel. The results show that the transmitted signal undergoes significant attenuation, particularly over the undersea optical channel. At the reference distance of 1.025 km with Jerlov water type I, a bit error rate performance of 10^?4 is achieved with a data rate of 1 Mbps. The S2US was further verified with experiments in terms of received signal level on a laboratory scale. The comparative analysis demonstrates that the simulation and experiment results are in good agreement.