Quantification of the Phase Transformation Kinetics in High Chromium Cast Irons Using Dilatometry and Metallographic Techniques

Metallurgical and Materials Transactions A - Further development of high chromium cast irons (HCCI) is based on tailoring the microstructure, necessitating an accurate control over the phase...     

Chemical Recycling of Carbon Fiber Reinforced Epoxy Composites Using Mild Conditions

The increased use of carbon fiber reinforced thermosets generates more waste and end-of-life products. However, an efficient recycling method for the expensive carbon fibers has not yet been developed. The selective decomposition of amine-cured epoxy resin under mild conditions is presented. A two-step method was investigated to decompose the epoxy resin. The optimum parameters were initially determined using a model compound. By analysis of the reaction products, a cleavage of the C–N bond according to the Cope elimination could be proven. Therefore, the Cope elimination is suggested as the main step of the decomposition of amine-cured epoxy resins in presence of hydrogen peroxide. By dissolving the resin, it is possible to recover resin-free fibers with unimpaired mechanical properties.     

Repairing an aggregation-based smart metering system

International Journal of Information Security - Smart meters inform the electricity suppliers about the consumption of their clients in short intervals. Fine-grained electricity consumption...     

Evaluation of Damage Degree of Inconel 718 Alloy with the Use of Non-Destructive Methods

The article presents results of the investigation of the quantitative evaluation of the degree of damage, described by the measure of accumulated plastic strain obtained in a static tensile test, using selected non-destructive techniques. Inconel 718 alloy was tested. The tests were conducted using a new type of specimens of variable cross-sectional area of measuring part. This provided a continuous distribution of plastic strain in the gage part of the specimen. The permanent deformation that varies along the sample axis enables an analysis of damage induced by a plastic deformation. The proposed method enables replacing the series of specimens by one sample. Degradation of the alloy corresponds with the changes of the electromagnetic properties of the material—the phase angle of the complex impedance of the eddy current, as well as with acoustics properties of material—acoustic birefringence of ultrasonic waves. It allows to determine the degree of damage of the material using noninvasive, non-destructive methods. Using the damage parameter proposed by Johnson it is possible to obtain the correlation between the non-destructive results and a damage degree of the material. The presented testing method delivers information about changes in the material structure caused by permanent deformation.

     

Sustainable Syngas Production by High-Temperature Co-electrolysis

High-temperature co-electrolysis shows comparable performance to steam electrolysis. Current densities above 1 A cm⁻² can be reached between 700 °C and 800 °C. Tailor-made syngas is produced, mainly determined by the reactant ratio. The experimental results are supported by modeling. Durability tests with cathode-supported cells show increased voltage degradation rates during electrolysis compared to fuel cell operation. Nickel depletion is found to be the main cause.     

Fast Motion Planning by Parallel Processing – a Review

One of the many features needed to support the activities of autonomoussystems is the ability to plan motion. This enables robots to move in theirenvironment securely and to accomplish given tasks. Unfortunately, thecontrol loop comprising sensing, planning, and acting has not yet beenclosed for robots in dynamic environments. One reason involves the longexecution times of the motion planning component. A solution for thisproblem is offered by the use of highly parallel computation. Thus, animportant task is the parallelization of existing motion planning algorithmsfor robots so that they are suitable for highly parallel computation. Inseveral cases, completely new algorithms have to be designed, so that aparallelization is feasible. In this survey, we review recent approaches tomotion planning using parallel computation. As a classification scheme, weuse the structure given by the different approaches to the robotsmotion planning. For each approach, the available parallel processingmethods are discussed. Each approach is assigned a unique class. Finally,for each research work referenced, a list of keywords is given.     

A Novel Flexible Hybrid Battery–Supercapacitor Based on a Self‐Assembled Vanadium‐Graphene Hydrogel

A novel flexible hybrid battery–supercapacitor device is proposed consisting of high specific surface area electrodes paired with an electrolyte, which contains a redox species that can exist in more than two oxidation states. The two initially equal half‐cells of the device consist of a reduced graphene oxide hydrogel which encapsulates vanadium ions, synthesized with a single‐step method. During charge, the oxidation state of the vanadium ions changes, resulting in two half‐cells with different potentials which considerably increases the energy density. The achieved maximum capacity of more than 225 mAh g^?1 is roughly eight times higher than that of comparable graphene hydrogel supercapacitors without vanadium content, but the potentiostatic charging time is only double. Operated as a supercapacitor, it retains 95% of the initial capacitance over 1000 cycles. As battery, the losses are more significant, retaining around 50% of the initial capacity. However, these losses during battery operation can be almost entirely restored by electric measures. The vanadium ion addition also improves the self‐discharge characteristics of the device. Moreover, the self‐discharge does not permanently damage the hybrid device since both half‐cells initially consist of the same vanadium graphene hydrogel and discharging resets it to initial conditions.