Force control of twisted and coiled polymer actuators via active control of electrical heating and forced convective liquid cooling

For decades, numerous artificial muscles have been proposed in order to implement beneficial features of biological muscles into robotics. Unfortunately, traditional artificial muscles experienced difficulties in imitating properties of the biological muscles due to mechanical and control issues. Recently, twisted and coiled polymer actuators (TCP) have been shown to produce large mechanical power via thermal stimulations and strong linearity. In this paper, a high-performance TCP thermally cycled by electrical heating and forced convective liquid cooling is designed and associated control algorithms are presented. We elaborate the model of the TCP that is simple, yet provides insight into how the electrical heating and the forced convective liquid cooling contribute to the TCP actuation. The proposed model is verified by experimental studies. Based on the proposed model, we design a feedforward–feedback controller and switching laws, which actively control the TCP in both the heating and cooling cycles. Furthermore, we extend our control methodology to agonist–antagonist TCPs. From the experimental studies, the proposed method is shown to be effective in both single TCP and antagonistic TCPs.     

Hydrophobic Tagged Dihydrofolate Reductase for Creating Misfolded Glycoprotein Mimetics

In the endoplasmic reticulum (ER), nascent glycoproteins that have not acquired the native conformation are either repaired or sorted for degradation by specific quality‐control systems composed by various proteins. Among them, UDP‐glucose:glycoprotein glucosyltransferase (UGGT) serves as a folding sensor in the ER. However, the molecular mechanism of its recognition remains obscure. This study used pseudo‐misfolded glycoproteins, comprising a modified dihydrofolate reductase with artificial pyrene–cysteine moiety on the protein surface (pDHFR) and Man₉GlcNAc₂‐methotrexate (M9‐MTX). All five M9‐MTX/pDHFR complexes, with a pyrene group at different positions, were found to be good substrates of UGGT, irrespective of the site of pyrene modification. These results suggest UGGT's mode of substrate recognition is fuzzy, thus allowing various glycoproteins to be accommodated in the folding cycle.     

Effects of water chemistry and potential distribution on electrochemical corrosion potential measurements in 553 K pure water

The effects of water chemistry distribution on the potential of a reference electrode and of the potential distribution on the measured potential should be known qualitatively to obtain accurate electrochemical corrosion potential (ECP) data in BWRs. First, the effects of oxygen on a platinum reference electrode were studied in 553 K pure water containing dissolved hydrogen (DH) concentration of 26–105 μg kg^?1 (ppb). The platinum electrode worked in the same way as the theoretical hydrogen electrode under the condition that the molar ratio of DH to dissolved oxygen (DO) was more than 10 and that DO was less than 100 ppb. Second, the effects of potential distribution on the measured potential were studied by using the ECP measurement part without platinum deposition on the surfaces connected to another ECP measurement part with platinum deposition on the surfaces in 553 K pure water containing 100–130 ppb of DH or 100–130 ppb of DH plus 400 ppb of hydrogen peroxide. Measured potentials for each ECP measurement part were in good agreement with literature data for each surface condition. The lead wire connecting point did not affect the measured potential. Potential should be measured at the nearest point from the reference electrode in which case it will be not affected by either the potential distribution or the connection point of the lead wire in pure water.     

A Two‐Stage Stochastic Mixed‐Integer Programming Approach to the Smart House Scheduling Problem

A “smart house” is a highly energy‐optimized house equipped with photovoltaic (PV) systems, electric battery systems, fuel cell (FC) cogeneration systems, electric vehicles (EVs), and so on. Smart houses are attracting much attention recently because of their enhanced ability to save energy by making full use of renewable energy and by achieving power grid stability despite an increased power draw for installed PV systems. Yet running a smart house's power system, with its multiple power sources and power storages, is no simple task. In this paper, we consider the problem of power scheduling for a smart house with a PV system, an FC cogeneration system, and an EV. We formulate the problem as a mixed‐integer programming problem, and then extend it to a stochastic programming problem involving recourse costs to cope with uncertain electricity demand, heat demand, and PV power generation. Using our method, we seek to achieve the optimal power schedule running at the minimum expected operation cost. We present some results of numerical experiments with data on real‐life demands and PV power generation to show the effectiveness of our method. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(4): 48–58, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22336     

Homogeneous Strain Introduction Using Reciprocation Technique in High-Pressure Sliding

Metallurgical and Materials Transactions A - This study examines strain distribution occurring in the high-pressure sliding (HPS) processing for rods of pure Al and an AZ61 alloy. The strain...     

A novel spherical carbon

We developed a novel spherical carbon material. The spherical carbon is composed of a high density of carbon nanotubes or nanofilaments, and includes an oxidized diamond particle as a core. Syntheses of this carbon in high volume with high selectivity may be possible. It is expected that this carbon will be useful as a catalyst material for fuel cells, electric double-layer capacitors, etc.     

Microstructure of ion-implanted region in TiNi alloy

TiNi alloy samples implanted with various fluences of 3 MeV Cu²⁺ ions were characterized by transmission electron microscope (TEM) and X-ray diffractometer. Cross-sectional TEM images of the samples showed that amorphous region was seen at the fluence of 10¹⁴ ions cm^?2 in case of ion implantation at 300 K of the substrate temperature, but in case of ion implantation at 100 K it did not appear even at 10¹⁵ ions cm^?2. These results were also confirmed by X-ray diffraction profiles of the same samples. Consequently, the extent of microstructure change of TiNi alloy by ion implantation was different depending on the substrate temperature.     

Comparison of CTOD standards: BS 7448-Part 1 and revised ASTM E1290

Crack tip opening displacement (CTOD) has been calculated using the plastic hinge model with an assumed rotational center since the British Standards Institution (BS) standardized BS5762 in 1979. The American Society for Testing and Materials (ASTM) accepted the plastic hinge model and standardized E1290 in 1989. However, ASTM revised E1290 in 2002, and has proposed a conversion from J to CTOD. CTOD-based fracture toughness evaluation has been widely used for the defect assessment of many welded structural components, and two different CTOD calculations could lead to confusion for Fitness-for-Service. In this study, the effects of CTOD testing methodologies on CTOD values were investigated according to round robin tests conducted by the Japan Welding Engineering Society (WES), and the concept of CTOD as a fracture parameter is discussed.