Additive increase rate accelerator

Abstract. We propose AIRA, an Additive Increase Rate Accelerator. AIRA extends AIMD functionality towards adaptive increase rates, depending on the level of network contention and bandwidth availability. In this context, acceleration grows when resource availability is detected by goodput/throughput measurements and slows down when increased throughput does not translate into increased goodput as well. Thus, the gap between throughput and goodput determines the behavior of the rate accelerator. We study the properties of the extended model and propose, based on analysis and simulation, appropriate rate decrease and increase rules. Furthermore, we study conditional rules to guarantee operational success even in the presence of symptomatic, extra-ordinary events. We show that analytical rules can be derived for accelerating, either positively or negatively, the increase rate of AIMD in accordance with network dynamics. Indeed, we find that the "blind", fixed Additive Increase rule can become an obstacle for the performance of TCP, especially when contention increases. Instead, sophisticated, contention-aware additive increase rates may preserve system stability and reduce retransmission effort, without reducing the goodput performance of TCP

Effect of Vulcanization System and Carbon Black on Mechanical and Swelling Properties of EPDM Blends

EPDM (Ethylene propylene diene monomer) is one of synthetic rubber that widely used in automotive. It must be vulcanized and added by other materials before used. The aim of this study is to investigate the effect of vulcanization system and the addition of carbon black (CB) to the mechanical properties and swelling characteristic of EPDM. This research used three vulcanization system, conventional vulcanization (CV), efficient vulcanization (EV) and semi-efficient vulcanization (SEV) with the variation of carbon black 50, 60, 70 phr (per hundred resin). This research showed that EV system resulted faster vulcanization time and lower delta torque than SEV and CV systems. This system also performed the highest tensile strength, elongation, and tear strength, while SEV system resulted the highest hardness. Furthermore, the conventional vulcanization system resulted the lowest swelling index

Effect of substituted phenylnadimides on processing and properties of PMR polyimide composites

Three nitrophenylnadimide cure initiators and two phenylnadimides (without nitros) were evaluated as additives to PMR-15 resins and Celion 6000 graphite fiber composites. The results of a resin screening study eliminated all of the additives except 3-nitrophenylnadimide (NO2PN) for use as a low temperature curing additive for PMR-15. Thus, NO2PN and the two control additives were investigated in PMR-15 formulations from which Celion 6000 graphite fiber/PMR-15 composites were processed both with low temperature (274 C) and normal (316 C) cure cycles. Comparisons of the two processing cycles, the resultant glass transition temperatures (Tg), the ambient, 274 and 316 C composite mechanical properties determined before and after 316 C postcure, the 316 C thermo-oxidative weight losses and the retention of 316 C composite mechanical properties are presented. Empirical correlations of the type and amount of nadimide additives with processing parameters, Tg, composite mechanical properties, composite thermo-oxidative stability and long term retention of 316 C composite mechanical properties are also presented

Beam Tests of Ionization Chambers for the NuMI Neutrino Beam

We have conducted tests at the Fermilab Booster of ionization chambers to be used as monitors of the NuMI neutrino beamline. The chambers were exposed to proton fluxes of up to 10$^{12}$ particles/cm$^2$/1.56$\mu$s. We studied space charge effects which can reduce signal collection from the chambers at large charged particle beam intensities.Comment: submitted to IEEE Trans Nucl. Sc

Fast Switching Ferroelectric Materials for Accelerator Applications

Fast switching (< 10 nsec) measurement results on the recently developed BST(M) (barium strontium titanium oxide composition with magnesium-based additions) ferroelectric materials are presented. These materials can be used as the basis for new advanced technology components suitable for high-gradient accelerators. A ferroelectric ceramic has an electric field-dependent dielectric permittivity that can be altered by applying a bias voltage. Ferroelectric materials offer significant benefits for linear collider applications, in particular, for switching and control elements where a very short response time of <10 nsec is required. The measurement results presented here show that the new BST(M) ceramic exhibits a high tunability factor: a bias field of 40-50 kV/cm reduces the permittivity by a factor of 1.3-1.5. The recently developed technology of gold biasing contact deposition on large diameter (110 cm) thin wall ferroelectric rings allowed ~few nsec switching times in witness sample experiments. The ferroelectric rings can be used at high pulsed power (tens of megawatts) for X-band components as well as at high average power in the range of a few kilowatts for the L-band phase-shifter, under development for optimization of the ILC rf coupling. Accelerator applications include fast active X-band and Ka-band high-power ferroelectric switches, high-power X-band and L-band phase shifters, and tunable dielectric-loaded accelerating structures.Comment: 7 pages, 6 figures, submitted to Proceedings of 2006 Advanced Accelerator Concepts Worksho

Chaos and Chaotic Phase Mixing in Galaxy Evolution and Charged Particle Beams

This paper discusses three new issues that necessarily arise in realistic attempts to apply nonlinear dynamics to galaxy evolution, namely: (i) the meaning of chaos in many-body systems, (ii) the time-dependence of the bulk potential, which can trigger intervals of {\em transient chaos}, and (iii) the self-consistent nature of any bulk chaos, which is generated by the bodies themselves, rather than imposed externally. Simulations and theory both suggest strongly that the physical processes associated with galactic evolution should also act in nonneutral plasmas and charged particle beams. This in turn suggests the possibility of testing this physics in real laboratory experiments, an undertaking currently underway.Comment: 16 pages, including 3 figures: an invited talk at the Athens Workshop on Galaxies and Chaos, Theory and Observation

A comparison of processing techniques for producing prototype injection moulding inserts.

This project involves the investigation of processing techniques for producing low-cost moulding inserts used in the particulate injection moulding (PIM) process. Prototype moulds were made from both additive and subtractive processes as well as a combination of the two. The general motivation for this was to reduce the entry cost of users when considering PIM. PIM cavity inserts were first made by conventional machining from a polymer block using the pocket NC desktop mill. PIM cavity inserts were also made by fused filament deposition modelling using the Tiertime UP plus 3D printer. The injection moulding trials manifested in surface finish and part removal defects. The feedstock was a titanium metal blend which is brittle in comparison to commodity polymers. That in combination with the mesoscale features, small cross-sections and complex geometries were considered the main problems. For both processing methods, fixes were identified and made to test the theory. These consisted of a blended approach that saw a combination of both the additive and subtractive processes being used. The parts produced from the three processing methods are investigated and their respective merits and issues are discussed