Energy dissipation and flux laws for unsteady turbulence

Direct Numerical Simulations of unsteady spatially periodic turbulence with time-dependent rms velocity u′(t) and integral length-scale L(t) show that not only the instantaneous energy dissipation rate but also the instantaneous energy flux at intermediate wavenumbers scales as View the MathML source where U0 and L0 are velocity and length scales characterizing initial or overall unsteady turbulence conditions. These high Reynolds number scalings are qualitatively different from the well-known u′(t)3/L(t) cornerstone scalings of equilibrium turbulence where the energy flux and dissipation are exactly balanced at all times

Physical processes behind the alignment effect

The radio/optical alignment effect for small powerful radio galaxies has been shown to be produced by shock waves formed by the interaction of the head of the jet and/or cocoon with clouds embedded in the interstellar/intergalactic medium. We present here preliminary results of analytical and numerical solutions that have been made to account for the production of implosive shock waves induced by embedding cold clouds in the radio lobe of expanding powerful radio sources.Comment: 4 pages. To be published in Multiwavelength AGN Surveys", Cozumel, Dec 8 - 12, 200

Application of the Bead Perturbation Technique to a Study of a Tunable 5 GHz Annular Cavity

Microwave cavities for a Sikivie-type axion search are subject to several constraints. In the fabrication and operation of such cavities, often used at frequencies where the resonator is highly overmoded, it is important to be able to reliably identify several properties of the cavity. Those include identifying the symmetry of the mode of interest, confirming its form factor, and determining the frequency ranges where mode crossings with intruder levels cause unacceptable admixture, thus leading to the loss of purity of the mode of interest. A simple and powerful diagnostic for mapping out the electric field of a cavity is the bead perturbation technique. While a standard tool in accelerator physics, we have, for the first time, applied this technique to cavities used in the axion search. We report initial results from an extensive study for the initial cavity used in the HAYSTAC experiment. Two effects have been investigated: the role of rod misalignment in mode localization, and mode-mixing at avoided crossings of TM/TE modes. Future work will extend these results by incorporating precision metrology and high-fidelity simulations.Comment: 6 pages, 4 figures, submitted to the 2nd Workshop on Microwave Cavities and Detectors for Axion Researc

Some Weyl modules of the algebraic groups of type E6E_6

Let $G$ be a simple algebraic group of type $E_6$ over an algebraically closed field of characteristic $p>0$. We determine the submodule structure of the Weyl modul es with highest weight $r\omega_1$ for $0\leq r\leq p-1$, where $\omega_1$ is the fundamental weight of the standard $27$-dimensional module. In the process, the structures of other Weyl modules with highest weights linked to $r\omega_1$ are also found. %We also give some computations for the Weyl modules with highest weights %of the form $r(\omega_1+\omega_6)$, which arise in the study of %the graph automorphism and associated twisted finite groups.Comment: 25 page

An experimental validation of the fatigue damaging events extracted using the wavelet bump extraction (WBE) algorithm

This paper describes an experimental validation of the fatigue damaging events that were identified and extracted using a wavelet-based fatigue data editing technique. This technique, known as the Wavelet Bump Extraction (WBE) algorithm, is specifically designed to summarise a long record of fatigue variable amplitude (VA) loading whilst preserving the original load cycle sequence. Using WBE the fatigue damaging events were identified and extracted in order to produce a mission signal. In order to validate the effectiveness of WBE in practical applications a VA road load time history that was measured on a road vehicle suspension arm was taken as a case study. Uniaxial fatigue tests were performed using the original signal, the WBE mission signal and the individual WBE extracted segments. A mirror polished specimen of SAE 1042 steel was tested using a servo-hydraulic machine. The fatigue lives measured for these VA loadings were then compared to the fatigue lives calculated from a VA strain loading fatigue damage model. The results show a good fatigue life correlation at the coefficient of 0.98 between the prediction and experiment. For the road load time history considered, the WBE mission signal was found to be only 40% the time duration of the original time history while maintaining 60% of the fatigue damage according to analytical calculation and 87% according to experimental testing

Bump extraction algorithm for variable amplitude fatigue loading

This paper presents the development of a fatigue mission synthesis algorithm, called Wavelet Bump Extraction (WBE), for summarising long records of fatigue road load data. This algorithm is used to extract fatigue damaging events or bumps in the record that cause the majority of the fatigue damage, whilst preserving the load cycle sequences. Bumps are identified from characteristic frequency bands in the load spectrum using the 12th order Daubechies wavelet. The bumps are combined to produce a mission signal which has equivalent signal statistics and fatigue damage to the original signal. The WBE accuracy has been evaluated by observing the cycle sequence effects of the bump loadings. The WBE was compared with the time domain fatigue data editing method, so that the effectiveness of WBE can be verified. Using WBE, a substantial compression of the load-time history could be achieved for the purpose of accelerated fatigue tests in the automotive industry

Adjunctive strategies in the management of resistant, 'undilatable' coronary lesions after successfully crossing a CTO with a guidewire.

Successful revascularisation of chronic total occlusions (CTOs) remains one of the greatest challenges in the era of contemporary percutaneous coronary intervention (PCI). Such lesions are encountered with increasing frequency in current clinical practice. A predictable increase in the future burden of CTO management can be anticipated given the ageing population, increased rates of renal failure, graft failure and diabetes mellitus. Given recent advances and developments in CTO PCI management, successful recanalisation can be anticipated in the majority of procedures undertaken at high-volume centres when performed by expert operators. Despite advances in device technology, the management of resistant, calcific lesions remains one of the greatest challenges in successful CTO intervention. Established techniques to modify calcific lesions include the use of high-pressure non-compliant balloon dilation, cutting-balloons, anchor balloons and high speed rotational atherectomy (HSRA). Novel approaches have proven to be safe and technically feasible where standard approaches have failed. A step-wise progression of strategies is demonstrated, from well-recognised techniques to techniques that should only be considered when standard manoeuvres have proven unsuccessful. These methods will be described in the setting of clinical examples and include use of very high-pressure non-compliant balloon dilation, intentional balloon rupture with vessel dissection or balloon assisted micro-dissection (BAM), excimer coronary laser atherectomy (ECLA) and use of HSRA in various 'offlabel' settings

Radiation therapy for primary carcinoma of the extrahepatic biliary system. An analysis of 63 cases.

From 1976 to 1988, 63 patients received radiation therapy for primary cancers of the extrahepatic biliary system (eight gallbladder and 55 extrahepatic biliary duct). Twelve patients underwent orthotopic liver transplantation. Chemotherapy was administered to 13 patients. Three patients underwent intraluminal brachytherapy alone (range, 28 to 55 Gy). Sixty patients received megavoltage external-beam radiation therapy (range, 5.4 to 61.6 Gy; median, 45 Gy), of whom nine received additional intraluminal brachytherapy (range, 14 to 45 Gy; median, 30 Gy). The median survival of all patients was 7 months. Sixty patients died, all within 39 months of radiation therapy. One patient is alive 11 months after irradiation without surgical resection, and two are alive 50 months after liver transplantation and irradiation. Symptomatic duodenal ulcers developed after radiation therapy in seven patients but were not significantly related to any clinical variable tested. Extrahepatic biliary duct cancers, the absence of metastases, increasing calendar year of treatment, and liver transplantation with postoperative radiation therapy were factors significantly associated with improved survival