Numerical computation of tyre radiaion noise: a comparative study of different techniques

Increasingly stringent noise regulations concerning automotive vehicles particularly in Europe are forcing Tyre manufacturers as well as the automotive manufacturers to reduce radiated noise. With the future moving towards electric/hybrid vehicles, the ever present tyre noise will become more dominant. Even in the case of automotive engines running on fossil fuels, tyre noise dominates above speeds of 40 Km/h. Understanding the causes of tyre noise is the first step towards finding engineering solutions to reduce it. Numerical modelling can help the tyre engineer in understanding the causes of tyre-road noise with a design tool. In the present work, the noise radiated by the tyre surface is computed numerically using three different computational techniques. Both the time domain approach and the frequency domain approaches are used and the results are compared. The input structural vibrations are computed in ABAQUS (Ref. 1) and the results are then imported to LMSVirtual.Lab (Ref. 2) for further acoustic computations. As the main focus of this work is on the acoustic computations, only a brief description of the process involved in the structural vibration calculations is provided. In the present work, the “Horn effect” is inherently captured in the acoustic simulations. Two model tyres, viz., with tread pattern and with circumferential grooves is evaluated. The presence of tread leads to the phenomenon of stick slip and stick snap mechanisms contributing to the overall tyre noise. In addition, the motion of air through the grooves causes air pumping noise. It is to be noted that the structural vibration computations were performed on a rotating tyre that translated on a stationary road. In other words, the tyre underwent rotational as well as translational displacement. The acoustic computations are however performed on a stationary tyre model. One of the challenges addressed in the present work is the conversion of transient vibration results on a stationary acoustic mesh. The surface accelerations, required as boundary conditions, are converted to the frequency domain by the Fast Fourier Transformation for the Harmonic computations. The details of the structural models as well as the acoustic models and a short description of the techniques used in the computations of the radiated noise are described in the next section

Evaluate Feasibility of Sustainable and Economical Utilization of Biomass Gasification Byproducts

Renewable energy offers a way to sustain the development of a society in harmony with nature and available resources (Das, 2007). As a renewable energy technology, biomass gasification has received revived attention recently. Nevertheless, responsible disposal or utilization of ash generated from biomass gasification process remains a technical challenge that needs to be resolved, in order for this technology to be a truly sustainable system (Fernandez-Pereira et al., 2011). The overall objective of this study was to develop a unique, environmentally friendly technology to make value-added building materials from gasification solid waste, thereby managing solid waste efficiently and avoiding landfills, saving natural resources, and reducing greenhouse gas emissions. It is hoped that this investigation could benefit solid waste, gasification, and concrete/clay products industries, and could help protect the environment and communities. This project was also intended to explore the feasibility of using biomass gasification ash (BGA; a combination of fly ash and bottom ash) as an admixture in concrete materials. Cement production consumes a significant amount of energy. Biomass ash can be used to replace some portion of required cement in concrete mix as a sustainable construction practice, which can result in a significant energy savings to society. Through our lab-scale brick study, we determined that BGA can be used to replace clay and shale as raw materials in brick making. The replacement percentage level can be up to 10% by mass and 18% by volume. A concrete mix using 10% or 20% biomass gasification ash to replace cement was shown to have satisfactory compressive strength for field applications, typical of 3,000 psi grade concrete.Illinois Sustainable Technology Center, Prairie Research Institute, University of Illinois at Urbana-Champaign; Grant No. SR5Ope

A Case of Vanishing Metastatic Mass: Right Atrial Mass in the Setting of Primary Epithelioid Hemangioendothelioma of the Spine

Epithelioid hemangioendothelioma (EHE) is a rare low-grade vascular neoplasm that is characterized as intermediate between benign hemangioma and high-grade angiosarcoma affecting 1 in 1,000,000 people worldwide. It has been described throughout the body with lung, liver, skin, and bone being the most frequent sites. Primary EHE of the spine has been reported in 56 cases so far with no correlation of age and sex. Our case highlights a rare clinical presentation, etiopathogenesis, diagnosis, and treatment of EHE of the spine with metastasis to the right atrium. This is the first documented case of EHE of the spine with metastatic spread to the heart treated with bevacizumab leading to resolution of the heart metastatic mass. Further studies are warranted to develop a treatment formula for this rare tumor, to consider combination chemotherapy and new adjuvant targeted immunotherapies to prevent progression of disease

Instrumentation and control system architecture of ECRH SST1

The Electron Cyclotron Resonance Heating (ECRH) system is an important heating system for the reliable start-up of tokamak. The 42GHz and 82.6GHz Gyrotron based ECRH systems are used in tokomaks SST-1 and Aditya to carry out ECRH related experiments. The Gyrotrons are high power microwave tubes used as a source for ECRH systems. The Gyrotrons need to be handled with optimum care right from the installation to its Full parameter control operation. The Gyrotrons are associated with the subsystems like: High voltage power supplies (Beam voltage and anode voltage), dedicated crowbar system, magnet, filament and ion pump power supplies and cooling system. The other subsystems are transmission line, launcher and dummy load. A dedicated VME based data acquisition & control (DAC) system is developed to operate and control the Gyrotron and its associated sub system. For the safe operation of Gyrotron, two level interlocks with fail-safe logic are developed. Slow signals that are operated in scale of millisecond range are programmed through software and hardware interlock in scale of microsecond range are designed and developed indigenously. Water-cooling and the associated interlock are monitored and control by data logger with independent human machine interface

Processing of aluminum-graphite particulate metal matrix composites by advanced shear technology

Copyright @ 2009 ASM International. This paper was published in Journal of Materials Engineering and Performance 18(9) and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this paper for a fee or for commercial purposes, or modification of the content of this paper are prohibited.To extend the possibilities of using aluminum/graphite composites as structural materials, a novel process is developed. The conventional methods often produce agglomerated structures exhibiting lower strength and ductility. To overcome the cohesive force of the agglomerates, a melt conditioned high-pressure die casting (MC-HPDC) process innovatively adapts the well-established, high-shear dispersive mixing action of a twin screw mechanism. The distribution of particles and properties of composites are quantitatively evaluated. The adopted rheo process significantly improved the distribution of the reinforcement in the matrix with a strong interfacial bond between the two. A good combination of improved ultimate tensile strength (UTS) and tensile elongation (e) is obtained compared with composites produced by conventional processes.EPSR

Production and Decay of D_1(2420)^0 and D_2^*(2460)^0

We have investigated $D^{+}\pi^{-}$ and $D^{*+}\pi^{-}$ final states and observed the two established $L=1$ charmed mesons, the $D_1(2420)^0$ with mass $2421^{+1+2}_{-2-2}$ MeV/c$^{2}$ and width $20^{+6+3}_{-5-3}$ MeV/c$^{2}$ and the $D_2^*(2460)^0$ with mass $2465 \pm 3 \pm 3$ MeV/c$^{2}$ and width $28^{+8+6}_{-7-6}$ MeV/c$^{2}$. Properties of these final states, including their decay angular distributions and spin-parity assignments, have been studied. We identify these two mesons as the $j_{light}=3/2$ doublet predicted by HQET. We also obtain constraints on {\footnotesize $\Gamma_S/(\Gamma_S + \Gamma_D)$} as a function of the cosine of the relative phase of the two amplitudes in the $D_1(2420)^0$ decay.Comment: 15 pages in REVTEX format. hardcopies with figures can be obtained by sending mail to: [email protected]

Measurement of the branching fraction for Υ(1S)→τ+τ−\Upsilon (1S) \to \tau^+ \tau^-

We have studied the leptonic decay of the $\Upsilon (1S)$ resonance into tau pairs using the CLEO II detector. A clean sample of tau pair events is identified via events containing two charged particles where exactly one of the particles is an identified electron. We find $B(\Upsilon(1S) \to \tau^+ \tau^-) = (2.61~\pm~0.12~{+0.09\atop{-0.13}})$. The result is consistent with expectations from lepton universality.Comment: 9 pages, RevTeX, two Postscript figures available upon request, CLNS 94/1297, CLEO 94-20 (submitted to Physics Letters B

Study of the B^0 Semileptonic Decay Spectrum at the Upsilon(4S) Resonance

We have made a first measurement of the lepton momentum spectrum in a sample of events enriched in neutral B's through a partial reconstruction of B0 --> D*- l+ nu. This spectrum, measured with 2.38 fb**-1 of data collected at the Upsilon(4S) resonance by the CLEO II detector, is compared directly to the inclusive lepton spectrum from all Upsilon(4S) events in the same data set. These two spectra are consistent with having the same shape above 1.5 GeV/c. From the two spectra and two other CLEO measurements, we obtain the B0 and B+ semileptonic branching fractions, b0 and b+, their ratio, and the production ratio f+-/f00 of B+ and B0 pairs at the Upsilon(4S). We report b+/b0=0.950 (+0.117-0.080) +- 0.091, b0 = (10.78 +- 0.60 +- 0.69)%, and b+ = (10.25 +- 0.57 +- 0.65)%. b+/b0 is equivalent to the ratio of charged to neutral B lifetimes, tau+/tau0.Comment: 14 page, postscript file also available at http://w4.lns.cornell.edu/public/CLN

Measurement of the Decay Asymmetry Parameters in Λc+→Λπ+\Lambda_c^+ \to \Lambda\pi^+ and Λc+→Σ+π0\Lambda_c^+ \to \Sigma^+\pi^0

We have measured the weak decay asymmetry parameters (\aLC ) for two \LC\ decay modes. Our measurements are \aLC = -0.94^{+0.21+0.12}_{-0.06-0.06} for the decay mode $\Lambda_c^+ \to \Lambda\pi^+$ and \aLC = -0.45\pm 0.31 \pm 0.06 for the decay mode $\Lambda_c \to \Sigma^+\pi^0$. By combining these measurements with the previously measured decay rates, we have extracted the parity-violating and parity-conserving amplitudes. These amplitudes are used to test models of nonleptonic charmed baryon decay.Comment: 11 pages including the figures. Uses REVTEX and psfig macros. Figures as uuencoded postscript. Also available as http://w4.lns.cornell.edu/public/CLNS/1995/CLNS95-1319.p

Observation of the Ξc+\Xi_c^+ Charmed Baryon Decays to Σ+K−π+\Sigma^+ K^-\pi^+, Σ+Kˉ∗0\Sigma^+ \bar{K}^{*0}, and ΛK−π+π+\Lambda K^-\pi^+\pi^+

We have observed two new decay modes of the charmed baryon $\Xi_c^+$ into $\Sigma^+ K^-\pi^+$ and $\Sigma^+ \bar{K}^{*0}$ using data collected with the CLEO II detector. We also present the first measurement of the branching fraction for the previously observed decay mode $\Xi_c^+\to\Lambda K^-\pi^+\pi^+$. The branching fractions for these three modes relative to $\Xi_c^+\to\Xi^-\pi^+\pi^+$ are measured to be $1.18 \pm 0.26 \pm 0.17$, $0.92 \pm 0.27 \pm 0.14$, and $0.58 \pm 0.16 \pm 0.07$, respectively.Comment: 12 page uuencoded postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN