Design considerations for attachment and detachment in robot climbing with hot melt adhesives

Robust climbing in unstructured environments is a long-standing challenge in robotics research. Recently there has been an increasing interest in using adhesive materials for that purpose. For example, a climbing robot using hot melt adhesives (HMAs) has demonstrated advantages in high attachment strength, reasonable operation costs, and applicability to different surfaces. Despite the advantages, there still remain several problems related to the attachment and detachment operations, which prevent this approach from being used in a broader range of applications. Among others, one of the main problems lies in the fact that the adhesive characteristics of this material were not fully understood fin the context of robotic climbing locomotion. As a result, the previous robot often could not achieve expected locomotion performances and "contaminated" the environment with HMAs left behind. In order to improve the locomotion performances, this paper focuses on attachment and detachment operations in robot climbing with HMAs. By systematically analyzing the adhesive property and bonding strength of HMAs to different materials, we propose a novel detachment mechanism that substantially improves climbing performances without HMA traces. © 2012 IEEE.

Robotic body extension based on hot melt adhesives

The capability of extending body structures is one of the most significant challenges in the robotics research and it has been partially explored in self-reconfigurable robotics. By using such a capability, a robot is able to adaptively change its structure from, for example, a wheel like body shape to a legged one to deal with complexity in the environment. Despite their expectations, the existing mechanisms for extending body structures are still highly complex and the flexibility in self-reconfiguration is still very limited. In order to account for the problems, this paper investigates a novel approach to robotic body extension by employing an unconventional material called Hot Melt Adhesives (HMAs). Because of its thermo-plastic and thermo-adhesive characteristics, this material can be used for additive fabrication based on a simple robotic manipulator while the established structures can be integrated into the robot's own body to accomplish a task which could not have been achieved otherwise. This paper first investigates the HMA material properties and its handling techniques, then evaluates performances of the proposed robotic body extension approach through a case study of a "water scooping" task. © 2012 IEEE.

A trapped field of 17.6 T in melt-processed, bulk Gd-Ba-Cu-O reinforced with shrink-fit steel

The ability of large-grain (RE)Ba2Cu3O7-δ ((RE)BCO; RE = rare earth) bulk superconductors to trap magnetic fields is determined by their critical current. With high trapped fields, however, bulk samples are subject to a relatively large Lorentz force, and their performance is limited primarily by their tensile strength. Consequently, sample reinforcement is the key to performance improvement in these technologically important materials. In this work, we report a trapped field of 17.6 T, the largest reported to date, in a stack of two silver-doped GdBCO superconducting bulk samples, each 25 mm in diameter, fabricated by top-seeded melt growth and reinforced with shrink-fit stainless steel. This sample preparation technique has the advantage of being relatively straightforward and inexpensive to implement, and offers the prospect of easy access to portable, high magnetic fields without any requirement for a sustaining current source. © 2014 IOP Publishing Ltd.

Improved purity of long-wavelength InAsSb epilayers grown by melt epitaxy in fused silica boats

In this study, we first present the process of the melt epitaxial (ME) growth method, and the improvement of low-temperature electron mobility of the long-wavelength InAsSb epilayers grown by ME in a fused silica boat. The electrical properties were investigated by van der Pauw measurement at 300 and 77 K. It is seen that the electron mobility of the InAsSb samples grown by graphite boat decreased from 55,700 to 26,600 cm(2)/V s when the temperature was reduced from 300 to 77 K, while for the samples grown by fused silica boat, the electron mobility increased from 52,600 at 300 K to 54,400 cm(2)/V s at 77 K. The electron mobility of 54,400cm(2)/Vs is the best result, so far, for the InAsSb materials with cutoff wavelength of 8-12 mum at 77 K. This may be attributed to the reduction of the carbon contamination by using a fused silica boat instead of a graphite boat. (C) 2002 Elsevier Science B.V. All rights reserved.

Liquid encapsulated-melt zone processing of GaAs

A liquid encapsulated melt Bone process has been developed for single crystal growth of GaAs. Single crystals of 40 mm long have been grown with this technique. To avoid unwanted nucleation events and maintain a constant crystal diameter, from top to bottom growth using a short zone with a convex zone surface was found to give the best results. An arsenic overpressure was used to in conjunction with a B2O3 encapsulant in order to suppress arsenic dissociation from the melt and maintain the stoichiometry of the crystal.

Electrical properties of semi-insulating GaAs grown from the melt under microgravity conditions

A technologically important undoped semi-insulating (SI) GaAs single crystal was successfully grown in the Chinese recoverable satellite as far as we know for the first time by using a similar growth configuration described previously. The experimental results proved that the space SI GaAs crystals have a lower density of defects and defect-impurity complexes as well as a better uniformity.

Water-soluble part of the aerosol in the dust storm season - evidence of the mixing between mineral and pollution aerosols

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Crystallographic and electrochemical characteristics of melt-spun Ti–Zr–Ni–Y alloys

Ti45Zr30Ni25Yx (x = 1, 3, 5 and 7) alloys were prepared by melt-spinning at wheel velocity of 20 m s(-1). The effect of additive Y on phase structure and electrochemical performance of melt-spun alloys was investigated. Ti45Zr30Ni25Yx melt-spun alloys were composed of I-phase and amorphous phase. T

Crystallographic and electrochemical characteristics of melt-spun Ti-Zr-Ni-La alloys

Ti-based icosahedral quasicrystalline phase (I-phase) exhibited excellent hydrogen storage property for special structure. Unfortunately, the application as the negative electrode material of the nickel-metal hydride batteries was limited due to the poor electrochemical kinetics. Meanwhile, rare-earth element was beneficial to the electrochemical properties of Ti, Zr-based alloy.