Ultraviolet‐ray treatment of polysulfone membranes on the O2/N2 and CO2/CH4 separation performance

UV irradiation on polysulfone (PSF) membranes was studied to improve their gas‐separation properties. Membranes with 19–25% PSF contents were prepared by the phase‐inversion method, and the membrane surface was modified with UV rays with a wavelength of 312 nm and a power of 360 µw/cm². Measurements of gas permeation were conducted with pure carbon dioxide (CO₂), methane (CH₄), oxygen (O₂), and nitrogen (N₂) gases under 3–8 bar pressure at 25°C. Fourier transform infrared spectrometry revealed that the polar functional groups of hydroxyl and carbonyl were introduced by UV irradiation. The water contact angle of the treated membrane was reduced from 70–75° to 10–12° after 12 h of UV exposure. Scanning electron microscopy observation showed that the dense skin layer increased as the polymer concentration increased. After UV treatment, the permeation of O₂ decreased from 0.4–3.4 to 0.2–2.3 m³ m^?2 h^?1 bar^?1, whereas that of N₂, CO₂, and CH₄ increased for all of the pressures used from 0.1–1.7 m³ m^?2 h^?1 bar^?1 to about 0.1–3.4 m³ m^?2 h^?1 bar^?1; this depended on the applied pressure and the PSF content. As a result, the selectivity ratio of O₂/N₂ decreased from 1.9–7.8 to 0.6–1.5, whereas that of CO₂/CH₄ increased from 0.9–2.6 to 1.1–6.1. Moreover, the O₂/N₂ and CO₂/CH₄ of the untreated and the treated membranes decreased with increasing pressure and increased with increasing polymer concentration. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42074.     

Iterative design of a semi-autonomous social telepresence robot research platform: a chronology

Our research focuses on how a telepresence robot operator, the people with the robot, and the robot itself collaborate so that the operator reaches his/her intended destination. Our research requires higher levels of autonomous navigation so that the robot can, for example, go to a specified destination and follow a person. However, commercial telepresence robots are primarily teleoperated, and only a few provide assisted navigation around obstacles. Our system must include sensors and processing to enable these capabilities. We present the chronology of our iterative design for augmenting two VGo Communications’ VGo robots, Hugo and Margo, over a period of 3 years. We detail the requirements and design constraints encountered while developing our telepresence robot platforms.     

A prototype safety system for new on-the-job training (OJT) in an anthropocentric cell manufacturing system

The anthropocentric cell manufacturing system (ACMS) discussed consists of a skill-based manufacturing scheduling system, a new on-the-job training (New OJT) system and a safety system. The New OJT was developed using e-learning and automated guided vehicle (AGV)-arm robot as a teacher for CNC machine training. Since the machines and the AGV-arm robot are automatic devices, controlled by computer programs, the dangers might arise during training. Therefore, the safety system is required to ensure that a learner will be safe. We propose a prototype of safety system with designed machine-protection in order to protect the learner from dangerous behaviours during a level 1 training of a New OJT in ACMS. The machine-protection focused on protection from danger using image processing with a background subtraction technique and comparison of objects' position. We also evaluated safety assessments of the learners, consisting of human error probabilities (HEP) and a human error rate (HER). The prototype of this developed safety system showed that the machine-protection certainly raises a warning alarm when the learner rises into dangerous zones during the training. The evaluated safety assessments showed that our designed New OJT training level 1 course performed more efficient safety performance for self-training of the learner.     

Behavior and Simulation of Deep Cement Mixing (DCM) and Stiffened Deep Cement Mixing (SDCM) Piles Under Full Scale Loading

A new kind of Deep Cement Mixing (DCM) pile called Stiffened Deep Mixing Pile (SDCM) is introduced to mitigate the low flexural strength and unexpected failures of DCM piles. A jet grouting method with a jet pressure of 22 MPa, was utilized in the installation of DCM piles. The SDCM pile consists of a DCM pile with a precast reinforced concrete core pile inserted at its center. Pile and embankment load tests were conducted, and then the results of the field load tests were simulated by a 3D finite element method (FEM) to back-analyze and confirm the related design parameters. These parameters were then used further in numerical experiments. The field test results showed that the settlements and lateral movements of the SDCM pile using a prestressed concrete core pile with area ratio (A_core/A_DCM) of 0.17 and a length ratio of 0.85 was less than those of the DCM pile by 40% and 60%, respectively. Moreover, the SDCM pile foundation increased the bearing capacity by as much as 2.2 times. The average lateral pile capacity of the SDCM piles was 15 times higher than the DCM piles. A strength reduction factor of 0.40 was obtained at the concrete core and the DCM interface from the full scale pullout test. The behavior of both the DCM and SDCM piles was confirmed from the subsequent 3D FEM simulations. From the 3D FEM simulations, the length of the concrete core pile had more influence on the settlements of the SDCM pile than its cross-sectional area. However, both the length and cross-sectional area of concrete core pile affected the lateral resistance of the SDCM pile.