Target strength effect on penetration by shaped charge jets

A limit of the applicability of the hydrodynamic theory was determined for penetration into targets of finite strength. At impact velocities below a limiting velocity, the target strength cannot be considered negligible. The limiting velocity is dependent on the target hardness and density. For the high-hardness aluminum and titanium alloys used in this paper, the limiting velocity, about 3.0 km/s, was found to lie in the range of velocities typical of shaped charge jets. Penetration into the aluminum and titanium alloys by portions of the jet with velocities below 3 km/s was studied experimentally; the depths of penetration were found to be significantly smaller as compared to the hydrodynamic predictions. This deviation has been attributed to the target strength effect.     

HgCdTe sampling circuit

The demonstration, using HgCdTe MISFETs, of a sampling circuit with output buffer amplifier is reported. Using the circuit, correlated double sampling is demonstrated at speeds typical of those required for focal plane arrays. Using a swept sine input, the circuit's transfer function is verified. The circuit was fabricated on epitaxially grown HgCdTe, with a cutoff wavelength of 3.56 mu m at 77 K.<>     

Project to Develop an Interoperable Seafood Traceability Technology Architecture: Issues Brief

The Interoperable Seafood Traceability Technology Architecture Issues Brief reflects the growing need to establish a global, secure, interoperable support system for seafood traceability. Establishing effective traceability systems relies on the development of a cohesive and consistent approach to the delivery of information technology capabilities and functions. The ability of business to utilize traceability for commercial gain is heavily influenced by the supply chain in which they operate. The Issues Brief describes factors associated with enterprise‐level traceability systems that will impact the design of technology architecture suited to enabling whole chain interoperable traceability. The Brief details why a technology architecture is required, what it means for industry in terms of benefits and opportunities, and how the architecture will translate into practical results. The current situation of many heterogeneous proprietary systems prevents global interoperable traceability from occurring. Utilizing primary research and lessons learned from other industries, the Brief details how the present situation can be addressed. This will enable computerized information systems to communicate syntactically by sharing standardized packages of data. The subsequent stage, semantic interoperability, is achieved by establishing a common language (ontology). The report concludes with a series of recommendations that industry can act upon to design a technology architecture suited to enabling effective global interoperable traceability.     

Rollout Strategy to Implement Interoperable Traceability in the Seafood Industry

Verifying the accuracy and rigor of data exchanged within and between businesses for the purposes of traceability rests on the existence of effective and efficient interoperable information systems that meet users’ needs. Interoperability, particularly given the complexities intrinsic to the seafood industry, requires that the systems used by businesses operating along the supply chain share a common technology architecture that is robust, resilient, and evolves as industry needs change. Technology architectures are developed through engaging industry stakeholders in understanding why an architecture is required, the benefits provided to the industry and individual businesses and supply chains, and how the architecture will translate into practical results. This article begins by reiterating the benefits that the global seafood industry can capture by implementing interoperable chain‐length traceability and the reason for basing the architecture on a peer‐to‐peer networked database concept versus more traditional centralized or linear approaches. A summary of capabilities that already exist within the seafood industry that the proposed architecture uses is discussed; and a strategy for implementing the architecture is presented. The 6‐step strategy is presented in the form of a critical path.     

CEGB ASSESSMENT PROCEDURE FOR DEFECTS IN PLANT OPERATING IN THE CREEP RANGE

In recent years considerable progress has been made in research work addressing the behaviour of defects at elevated temperature. Developments have been made both in structural assessment techniques and in methods for analysing representative materials data. On the basis of these developments a procedure has been produced within the CEGB for the assessment of defects in plant operating in the creep range under loadings for which creep rather than creep-fatigue is the dominant failure mechanism. This paper describes the CEGB procedure. Calculations are required for three events: the time for overall structural failure by continuum damage mechanisms; the time for incubation prior to crack extension; and the time for subsequent growth to a maximum tolerable defect size. Methods are presented for calculating these times and for obtaining the materials data required to perform the calculations.     

Field-extended field-effect transistors in 0.25-eV bandgap HgCdTe

A novel FET structure for use with 0.25-eV bandgap HgCdTe is described. The device, known as the field-extended field-effect transistor (FEFET), incorporates additional electrodes to control the surface electric field at the perimeter of the metallurgical diodes comprising the source and the drain of the transistor. Surrounding the metallurgical diodes with field-induced inversion regions improves the FEFET avalanche breakdown and subthreshold leakage characteristics as compared to standard MISFETs fabricated in HgCdTe. The FEFET is particularly attractive for switching applications or other uses requiring a high drain-to-source bias and a gate bias near the threshold potential     

Post weld heat treatment of a niobium stabilized austenitic weld metal

A study has been made of the effects of post weld heat treatments in the range 700°C to 900 °C on the microstructural, impact and creep crack growth properties of a 16Cr-8NI-6Mn-Mo, V, Nb, B austenitic weld metal. These treatments result in the progressive decomposition of delta-ferrite to M₂₃C₆ and a phase as well as enhanced precipitation of NbC; the time- temperature- precipitation characteristics have been determined. Impact energies are severely reduced, whereas the creep crack growth resistance of material heat treated at 800°C or 850°C is significantly better than for the as-deposited weld metal.     

Tetrahedral mesh generation using Delaunay refinement with non‐standard quality measures

This paper studies the practical performance of Delaunay refinement tetrahedral mesh generation algorithms. By using non‐standard quality measures to drive refinement, we show that sliver tetrahedra can be eliminated from constrained Delaunay tetrahedralizations solely by refinement. Despite the fact that quality guarantees cannot be proven, the algorithm can consistently generate meshes with dihedral angles between 18^circ and 154^°. Using a fairer quality measure targeting every type of bad tetrahedron, dihedral angles between 14^° and 154^° can be obtained. The number of vertices inserted to achieve quality meshes is comparable to that needed when driving refinement with the standard circumradius‐to‐shortest‐edge ratio. We also study the use of mesh improvement techniques on Delaunay refined meshes and observe that the minimum dihedral angle can generally be pushed above 20^°, regardless of the quality measure used to drive refinement. The algorithm presented in this paper can accept geometric domains whose boundaries are piecewise smooth. Copyright © 2011 John Wiley & Sons, Ltd.