Adiabatic shear localization in titanium and Ti-6 pct Al-4 pct V alloy

Ballistic impact experiments were conducted on 12.5 mm thick commercial purity titanium and Ti-6 pct Al-4 pct V alloy plates using steel “stepped” projectiles with 10.5 mm diameter. The impact velocities varied between 578 m per second and 846 m per second, and a flash X-ray technique was used to determine projectile velocity and to assure the normality of impact. The microstructural damage mechanisms associated with impact (shear band formation, shock wave propagation, and dynamic fracture) were analyzed by optical, and scanning and transmission electron microscopy. Elliptical and spherical cavities were observed along the bands. Microindentation hardness differences between the bands and adjacent regions were slight for the targets; for the projectiles, the hardness in the band was significantly lower than that of surrounding regions. Observation of the fractured regions along the bands showed unique features indicating possible melting. Transmission-electron microscopy of a shear band in titanium revealed microcrystalline features (∼0.3 μm diameter) with poorly defined grain boundaries. Formerly Graduate Student, Department of Metallurgical and Materials Engineering, New Mexico Institute of Mining and Technology, Socorro, NM 87801     

Microprocessor control of multiaxes continuous path motion

Continuous path position control systems differ from simple point-to-point controllers because of the additional requirement for path trajectory control. This paper describes a multimicrocomputer structure for the control of multiaxes continuous path motion. Path control is achieved by the means of real-time interpolation. Loop closures for position servomechanisms are implemented in software. Numerical control tasks are distributed in a manner to allow both interpolation and servo loop closure for each degree of freedom on a separate microcomputer. This approach has the advantage of expandibility from two to three or more degrees of freedom by simply adding extra axis controller microcomputer cards to the system.     

Total planning of combined district heating,cooling and power generation systems for a new town—Part II

The objective of this study is to introduce one of the main results of the project for studying energy conservation technologies in a new airport town, which is organized by the Osaka Science and Technology Center, Japan. First, based on the estimated energy demands in the new town, technological aspects are investigated for the district heating, cooling and hot water supply system. Then, the economic and energy saving characteristics are compared for several alternative systems according to the differences of the type of absorption refrigerating machine and so forth. Assuming that a combined heat and power plant is used as the heat source plant of the district thermal distribution system, the optimal combined district heating, cooling and power generation system has been selected from a comprehensive economic viewpoint. Lastly, it is ascertained that if fuel costs continue to rise at the rate of 8 per cent per year, the best energy conservation system becomes superior economically to the conventional district thermal distribution system.     

Interaction of soluble proteins with protein monolayers

The direction and strength of intermolecular forces at an air-water or oil-water interface is such that many proteins in the interface are distorted in structure. This involves substantial changes in solubility and cross-sectional area. Many of the changes can be accounted for by rupture of the secondary and tertiary bonds and are often irreversible. The hydrophilic groups of the protein will be concentrated in the aqueous phase and participate in interactions with normal proteins in the supporting solution. It can be shown that certain types of interaction between these hydrophilic groups of a protein monofilm and a soluble protein are dependent on the interfacial pressure, that they are sensitive to a small (one or more amino acid) change in structure of the protein. Evidence is given that they are related to certain antigen-antibody type reactions between molecules in three-dimensional systems. Since many proteins in vivo are exposed to oilwater and air-water interfaces, this laboratory model may have physiologic as well as chemical significance.