Ultrasonic behavior of plastically deformed and heat treated steel

Studies were made on the longitudinal ultrasonic velocity and its attenuation characteristics in medium carbon steel forging subjected to 0–60% hot upsetting followed by heat treatment. The fineness of ferrite and pearlite increased with increasing deformation and cooling rate during heat treatment. The area fraction of pearlite increased from 21% to 45% as well as the mean interlamellar spacing in pearlite decreased from 8.79 μm to 0.689 μm in the 40% deformed (upsetted) normalized sample It was observed that the ultrasonic velocity decreased with increasing degree of deformation. The velocity was found to be highest in the normalized steel acquiring a value of 5920 m/s and lowest in hardened steel acquiring a value of 4979 m/s. The attenuation decreased with increasing deformation resulting in increased back wall echo heights. The residual stresses on the surface of typical 60% deformed and annealed steel samples using x-ray diffractometry were measured to be — 39.7 MPa (compressive) and — 188.0 MPa (compressive) respectively.     

Use of singular value decomposition in system identification

Use of the singular value decomposition is suggested for problems of linear least-squares system identification rather than the usual method involving the normal equations.     

Effect of microstructure on mechanical properties of refractory Co-Cr-W-Ni alloy

A cobalt-base refractory alloy containing W, Ni, and Cr, which is widely used for making spacecraft components operating at high temperatures, is studied. Changes in the microstructure of the alloy are studied depending on the heat treatment, and the effect of these changes on mechanical properties at room and high temperatures is determined.     

Technical assessment of cryo-compressed hydrogen storage tank systems for automotive applications

On-board and off-board performance and cost of cryo-compressed hydrogen storage are assessed and compared to the targets for automotive applications. The on-board performance of the system and high-volume manufacturing cost were determined for liquid hydrogen refueling with a single-flow nozzle and a pump that delivers liquid H₂ to the insulated cryogenic tank capable of being pressurized to 272 atm. The off-board performance and cost of delivering liquid hydrogen were determined for two scenarios in which hydrogen is produced by central steam methane reforming (SMR) or by central electrolysis. The main conclusions are that the cryo-compressed storage system has the potential of meeting the ultimate target for system gravimetric capacity, mid-term target for system volumetric capacity, and the target for hydrogen loss during dormancy under certain conditions of minimum daily driving. However, the high-volume manufacturing cost and the fuel cost for the SMR hydrogen production scenario are, respectively, 2–4 and 1.6–2.4 times the current targets, and the well-to-tank efficiency is well short of the 60% target specified for off-board regenerable materials.     

Improving the quality of continuous copper rod

Southwire continuous rod technology has been used for approximately a quarter of a century to produce high-quality copper rod, and ongoing modifications to the process have improved not only the copper product, but the actual efficiency of the production system. Some of these developments have been achieved through automatic quality monitoring and the application of sophisticated control devices.     

Molecular characterization of human and mouse fatty acid amide hydrolases

Recently, we reported the isolation, cloning, and expression of a rat enzyme, fatty acid amide hydrolase (FAAH), that degrades bioactive fatty acid amides like oleamide and anandamide to their corresponding acids, thereby serving to terminate the signaling functions of these molecules. Here, we report the molecular characterization of both a mouse and a human FAAH and compare these enzymes to the rat FAAH. The enzymes are well conserved in primary structure, with the mouse and rat FAAHs sharing 91% amino acid identity and the human FAAH sharing 82% and 84% identity with the rat FAAH and mouse FAAH, respectively. In addition, the expressed human and rat FAAHs behave biochemically as membrane proteins of comparable molecular size and show similar, but distinguishable, enzymological properties. The identification of highly homologous FAAH proteins in rat, mouse, and human supports a general role for the fatty acid amides in mammalian biology.     

The differential induction machine: Theory and performance

This paper presents the theory and performance of a differential induction machine, which is a special type of induction machine having two shafts projected from the two ends of a single stator. Application of a differential load on the two shafts cause them to run at different speed as a motor, which permits true differential movement and thus can meet the requirements of a differential drive in an electric vehicle. The machine is also capable of regeneration in the differential mode. This paper presents the construction of the above machine and performance of the same based on experimental results from a laboratory prototype. The equivalent circuit of the motor has been presented and verified experimentally.     

A proposed structural model for amyloid fibril elongation: domain swapping forms an interdigitating {beta}-structure polymer

We propose a model illustrating how proteins, which differ intheir overall sequences and structures, can form the propagating,twisted ß-sheet conformations, characteristic of amyloids.Some cases of amyloid formation can be explained through a `domainswapping' event, where the swapped segment is either a ß-hairpinor an unstable conformation which can partially unfold and assumea ß-hairpin structure. As in domain swapping, herethe swapped ß-hairpin is at the edge of the structure,has few (if any) salt bridges and hydrogen bonds connectingit to the remainder of the structure and variable extents ofburied non-polar surface areas. Additionally, in both casesthe swapped piece constitutes a transient `building block' ofthe structure, with a high population time. Whereas in domainswapping the swapped fragment has been shown to be an