A Security Approach for the Example Sodium Fast Reactor

Increases in the spread of nuclear technology and the rise of non-state terrorism in the modern era has proved the need for effective security approaches to new nuclear facilities. Many documents about security approaches for nuclear plants are non-public material, however, making it difficult to teach others about the basics of security design. To alleviate this issue, we used available texts in the security realm to design a security approach for the Generation IV International Forum’s Example Sodium Fast Reactor. Our approach utilized infrared, microwave, fiber optic, and other advanced technologies to provide security for the special nuclear material present. While this is not meant to be a final approach for any one facility, it serves as an example for those wanting to learn about how to design security systems for both nuclear and non-nuclear plants

Impulse oscillometry identifies peripheral airway dysfunction in children with adenosine deaminase deficiency.

Adenosine deaminase-deficient severe combined immunodeficiency (ADA-SCID) is characterized by impaired T-, B- and NK-cell function. Affected children, in addition to early onset of infections, manifest non-immunologic symptoms including pulmonary dysfunction likely attributable to elevated systemic adenosine levels. Lung disease assessment has primarily employed repetitive radiography and effort-dependent functional studies. Through impulse oscillometry (IOS), which is effort-independent, we prospectively obtained objective measures of lung dysfunction in 10 children with ADA-SCID. These results support the use of IOS in the identification and monitoring of lung function abnormalities in children with primary immunodeficiencies

Hybrid carbon fibre–carbon nanotube composite interfaces

Both low and high modulus carbon fibres are coated with carboxylated single wall carbon nanotubes (SWNTs). It is shown that it is then possible to follow, for the first time, the local deformation of low modulus carbon fibres and composite interfaces using Raman spectroscopy. By deforming coated single carbon fibre filaments in tension, and following the shift in the position of a band located at ∼2660 cm−1 (2D band) it is possible to calibrate the local stress state of a fibre embedded in an epoxy resin. To follow the interface between the fibres and the epoxy resin, a thin film model composite is used. Point-to-point variation of stress along a single fibre, both inside and outside the resin, is recorded and stress transfer models are used to determine the interfacial shear stress (ISS). Values of the ISS (∼20 MPa) are obtained for the thin film model composites for untreated high modulus fibres. A beneficial interfacial effect of the presence of SWNTs on the surface of the high modulus carbon fibre samples is demonstrated resulting in an increase in the maximum ISS (>30 MPa) compared to uncoated samples. Similarly coated low modulus fibres exhibit a very high ISS (>50 MPa). These increases are attributed to an enhanced contact between the resin and the fibres due to an increased surface area as a result of the nanotubes and additional bonding caused due to the presence of carboxylate groups

Controlling and mapping interfacial stress transfer in fragmented hybrid carbon fibre-carbon nanotube composites

Copyright © 2014 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Composites Science and Technology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Composites Science and Technology Vol. 100 (2014), DOI: 10.1016/j.compscitech.2014.05.034Raman spectroscopy was used to map the stress transfer at the interface between high and low modulus carbon fibres in model composites when undergoing fragmentation. Both fibre surfaces were coated with two types of single wall carbon nanotubes (HiPCO and carboxylated nanotubes) in order to enhance the interfacial shear strength with an epoxy resin. For the low modulus carbon fibre this coating also enabled stress mapping at the interface. In both cases single fibres embedded in a dumbbell shaped model composite were deformed to cause fragmentation. When no further fragmentation took place the critical fibre length was calculated and converted to interfacial shear stress using classical Kelly–Tyson theory. These values were compared to data obtained using a Raman spectroscopic approach where the rate of change of stress with respect to distance along the fibre was measured directly. These data were then shown to fit a shear lag model. Two forms of single-wall carbon nanotubes were compared; namely unmodified and COOH modified. It was shown that only the COOH modified single wall carbon nanotubes increase the maximum interfacial shear stress significantly. Evidence of matrix yielding at the fibre ends is also presented and the possibility of the enhancement of the shear yield stress of the resin by the presence of the nanotubes is also discussed

Simulation, modelling and development of the metris RCA

In partnership with Metris UK we discuss the utilisation of modelling and simulation methods in the development of a revolutionary 7-axis Robot CMM Arm (RCA). An offline virtual model is described, facilitating pre-emptive collision avoidance and assessment of optimal placement of the RCA relative to scan specimens. Workspace accessibility of the RCA is examined under a range of geometrical assumptions and we discuss the effects of arbitrary offsets resulting from manufacturing tolerances. Degeneracy is identified in the number of ways a given pose may be attained and it is demonstrated how a simplified model may be exploited to solve the inverse kinematics problem of finding the “correct” set of joint angles. We demonstrate how the seventh axis may be utilised to avoid obstacles or otherwise awkward poses, giving the unit greater dexterity than traditional CMMs. The results of finite element analysis and static force modelling on the RCA are presented which provide an estimate of the forces exerted on the internal measurement arm in a range of poses

Characteristics, accuracy and reverification of robotised articulated arm CMMs

VDI article 2617 specifies characteristics to describe the accuracy of articulated arm coordinate measuring machines (AACMMs) and outlines procedures for checking them. However the VDI prescription was written with a former generation of machines in mind: manual arms exploiting traditional touch probe technologies. Recent advances in metrology have given rise to noncontact laser scanning tools and robotic automation of articulated arms – technologies which are not adequately characterised using the VDI specification. In this paper we examine the “guidelines” presented in VDI 2617, finding many of them to be ambiguous and open to interpretation, with some tests appearing even to be optional. The engineer is left significant flexibility in the execution of the test procedures and the manufacturer is free to specify many of the test parameters. Such flexibility renders the VDI tests of limited value and the results can be misleading. We illustrate, with examples using the Nikon RCA, how a liberal interpretation of the VDI guidelines can significantly improve accuracy characterisation and suggest ways in which to mitigate this problem. We propose a series of stringent tests and revised definitions, in the same vein as VDI 2617 and similar US standards, to clarify the accuracy characterisation process. The revised methodology includes modified acceptance and reverification tests which aim to accommodate emerging technologies, laser scanning devices in particular, while maintaining the spirit of the existing and established standards. We seek to supply robust re-definitions for the accepted terms “zero point” and “useful arm length”, pre-supposing nothing about the geometry of the measuring device. We also identify a source of error unique to robotised AACMMs employing laser scanners – the forward-reverse pass error. We show how eliminating this error significantly improves the repeatability of a device and propose a novel approach to the testing of probing error based on statistical uncertainty