Fourth International Symposium on Magnetic Suspension Technology

In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Fourth International Symposium on Magnetic Suspension Technology was held at The Nagaragawa Convention Center in Gifu, Japan, on October 30 - November 1, 1997. The symposium included 13 sessions in which a total of 35 papers were presented. The technical sessions covered the areas of maglev, controls, high critical temperature (T(sub c)) superconductivity, bearings, magnetic suspension and balance systems (MSBS), levitation, modeling, and applications. A list of attendees is included in the document

Energy absorption evaluation and design at the ballistic level in composites

The research presented in this thesis is directed towards the evaluation and understanding of a range of composite materials impacted at a ballistic level under both normal and oblique orientations, and the development of a novel recycled composite material with enhanced ballistic performance. It compares the ballistic performance of normal and oblique impacts of metallic and composite materials, describes the development, production and testing of a novel recycled composite material, and the performance of a Kolsky experiment on this novel material. For the Certification Authorities within the Aerospace Industry, the effects of angled impacts onto composites have not been addressed to the same extent as normal impacts, primarily because perpendicular impacts are largely considered to be the worst case scenarios. However, this research highlights certain aspects within the behaviour of composite materials in which that assumption may be too simplistic. Composites offer many advantages in ballistic protection but they are still relatively expensive and once damaged the ‘used’ material is usually discarded in secure landfill or burnt, and new pristine protective panels are required in their place. The development of a new recycled composite material could potentially therefore reduce costs, for example, if employed in partly replacing current battle-damaged polymeric armour panels used in the protection of air/land/sea vehicles, equipment and buildings. Further insight has been gained through the implementation of a Kolsky bar impact test based on a Hopkinson bar methodology, which has been modified to encompass a Taylor impact type concept. In this test, a polymeric specimen is fired against an instrumented steel bar, which measures the strain generated during the impact event, and the process of material deformation and disintegration is captured on video for subsequent analysis. Tests have been carried out on Aluminium, pristine cylindrical and cuboid Dyneema® specimens and also recycled cylindrical Dyneema® specimens.Open Acces

Small-Caliber Exterior Ballistics : Aerodynamic Coefficients Determination by CFD

The models used to calculate small-caliber projectile trajectories are often only drag-based, given the presumed short ranges and the assumed small variation of the aerodynamic parameters in flight. Depending on the type of application, "field" calibrations are then performed to compensate for the observed deviations. However, with the new small-caliber applications and the inherent increased challenges, these simplified methods do not yield satisfactory results anymore in terms of accuracy and attitude upon impact. In the first part, next to reviewing existing trajectography models, we discuss their implementation in our own trajectory program \textit{VTraj}, developed in LabVIEW. The six degrees of freedom (6 DoF) model allows to compute the flight of any symmetrical or asymmetrical projectile (spin- or fin- stabilized). Its parameters include a complete set of static and dynamic contributions, including Magnus and pitch damping forces \& moments. This model allows the analysis of all translation and angular motions of the projectile's body. The models give good agreement with published results on standard reference projectiles for the trajectory parameters. In part two, we focus on the methodology to capture the static and dynamic coefficients by steady and unsteady RANS methods for subsonic, transonic and supersonic flight conditions. Accurate resolution of the flow in the boundary layer and in the wake of the projectile proved to be of utmost importance for the correct determination of the coefficients. The coefficient extraction methods are assessed with published results for canonical shapes and good agreement is achieved. The results highlight the strong dependency of the pitch damping coefficient on the reduced pitch frequency which varies along the flight path. Rigid Body Dynamics (RBD) as well as Computational Fluid Dynamics (CFD) are finally combined in order to evaluate the behavior of specific small-caliber applications: non-lethal projectiles operating in the low subsonic domain, long-range projectiles with focus on transonic domain crossing, and asymmetric configuration are studied. The resolution of the dynamic flow around the projectile and the prediction of stability upon impact are confronted with experimental results and the match is very promising. The research also gives new insight into the diverse phenomena at hand in the transonic domain, or for projectiles with mass unbalance, and the change they impart on static and dynamic stability characteristics

Properties of concrete subjected to explosively generated impact and impulse loading.

The use of models to simulate full scale structural effects has long been attempted and various types of models have been developed. One type, the replica model, in which prototype materials are used was selected for this study. Much interest has been shown in the past on damage prediction based on extrapolation of the results from small explosive charge tests. In this study, scale model concrete ground slabs have been subjected to high rates of loading using explosively propelled copper and aluminium projectiles impacting on the concrete to air surface and explosive devices buried in the soil beneath the concrete slab. The copper or aluminium projectile was produced from a truncated cone of metal in direct contact with a shaped charge of RDX/TNT explosive. The subsurface charge was uncased PE4 plastic explosive inserted into a hole through the slab and into the soil. In many tests the hole was produced by the metal jet impact without any modification. Other scaled concrete targets have also been tested using explosively propelled projectiles. Transient results from the tests have been collected using high speed photography, electrical resistance strain gauges, crack velocity detection devices and a projectile velocity measurement system. Other measurements of post test damage have utilised stereoscopic photography, coloured particles of soil in the foundations of the concrete slabs and a scanning electron microscope. Concretes of various strengths and densities have been used but all conformed to a scaled down specification for pavement quality concrete. Explosive charges were similarly scaled in size from prototype devices. Some additional experimental work has been carried out to obtain fundamental data on the explosive charges and on 'perspex', metal and concrete blocks for calculation and comparison purposes. Comparisons are also made with work of a related nature undertaken at larger scales

Experimental study of aerodynamic behaviour of stretchable sport fabrics

In recent years, there has been great interest in the effects of different garments and their aerodynamic characteristics. It is widely believed that the reduction of aerodynamic drag can enhance athlete’s performance. There has been little understanding in the aerodynamic properties and behaviours of athlete’s garment as limited research is reported in the open literature. Therefore, the primary objective of this research is to understand the aerodynamic characteristics and gain a greater insight in order to establish relations between sports garments’ physical parameters and aerodynamic properties. A series of stretchable knitted and woven fabrics used in speed sports garments (e.g., sprint, cycling, speed skating, downhill skiing, ski jumping and swimming) have been studied for a wide range of Reynolds numbers (Re) and angles of attack (α). The findings revealed that the drag polar (C L /C D ratio) for 3D circular cylinder with smooth and rough surfaces (varied by knitted and woven fabrics) has been established for a range of Reynolds numbers (Re = 5.06 × 10 4 to 2.30 × 10 5 ) and angles of attack (α = 0° to 90°). The drag polar allows determining the aerodynamic efficiency of sports fabrics (i.e., garments) and their optimal design. The aerodynamic behaviour of knitted fabrics is found to be quite different to that of woven fabrics. With an increase of stretch, the surface morphology of knitted fabrics becomes courser and thereby triggers an early airflow transition. In contrast, the stretch on woven fabrics makes the surface morphology smoother which delays the flow transition. The minimum drag coefficient (C Dmin ) of stretchable knitted fabrics is directly proportional to relative roughness whereas the critical Reynolds numbers is inversely proportional to the relative roughness (ε = 1.39 × 10 -4 to 7.73 × 10 -4 ) within Reynolds numbers investigated (Re crit = 1.83 × 10 5 to 1.00 × 10 5 ). On the other hand, the minimum drag coefficient (C Dmin ) of stretchable woven fabrics is proportional to the relative roughness, however the relationship of critical Reynolds numbers (Re crit = 1.17 × 10 5 to 2.34 × 10 5 ) with the relative roughness (ε = 3.689 × 10 -4 to 1.319 × 10 -4 ) is non-linear. Knitted fabrics with lower relative roughness, distance and gap area between yarns generate greater aerodynamic efficiency (C L /C D ) at high Reynolds numbers. Similarly with the higher relative roughness, distance and gap area between yarns, the knitted fabrics offers an aerodynamic benefit at low Reynolds numbers. A notable reduction of aerodynamic benefit in woven fabrics was found under unstretched condition. However with increased stretches, the aerodynamic advantage (C L /C D ) increases almost linearly. The stretched woven fabrics are found to be aerodynamically beneficial at high Reynolds numbers whereas the stretched knitted fabrics are at low Reynolds numbers. The practical implication of these research findings is multi-fold. The drag polar of smooth and rough cylindrical surfaces can be applied not only for the development of engineered sports garments but also for the optimal athlete’s body orientation. Additionally, the findings can be utilised in developments of various projectile shapes for military and sports applications

NASA Automated Rendezvous and Capture Review. A compilation of the abstracts

This document presents a compilation of abstracts of papers solicited for presentation at the NASA Automated Rendezvous and Capture Review held in Williamsburg, VA on November 19-21, 1991. Due to limitations on time and other considerations, not all abstracts could be presented during the review. The organizing committee determined however, that all abstracts merited availability to all participants and represented data and information reflecting state-of-the-art of this technology which should be captured in one document for future use and reference. The organizing committee appreciates the interest shown in the review and the response by the authors in submitting these abstracts

Proceedings of the Seventeenth Annual Conference on Manual Control

Manual control is considered, with concentration on perceptive/cognitive man-machine interaction and interface

Advanced Radio Frequency Identification Design and Applications

Radio Frequency Identification (RFID) is a modern wireless data transmission and reception technique for applications including automatic identification, asset tracking and security surveillance. This book focuses on the advances in RFID tag antenna and ASIC design, novel chipless RFID tag design, security protocol enhancements along with some novel applications of RFID