An experimental model to describe the temperature variation of the disk during braking tests

In the present paper an experimental model is created to describe the temperature variation ofthe disk inexperiments performed on a laboratory-scale tribometer. A commercially available brake pad anddisk are used in the tests. The operating parameters seton the tribometer are a constant rotation of660 rpm, torque of 10Nm and 15Nm, braking time of 25s and 50s and initial temperature of 50°C and100°C. The evaluation of the thermal results is done by using a statistical model for analysis of variance(Anova). In order to obtain a mathematical equation to describe the temperature variation of the disk,a linear regression model is used. At the same time, the effect from both, temperature variation and initialtemperature, on the coefficient of friction are investigated.The effect of the temperature variation oncoefficient of friction is complex and it seems to not have correlation between them both. When the initialtemperature is changed from 50°C to 100°C the coefficient of friction is increased. The results from thecurrent paper shows that the experimental model can be used to predict the temperature variation of thedisk during braking tests performed on the tribometer

Relation between the cooling time and friction results in braking tests

The current paper intends to evaluate the influence of the cooling time on friction results duringbraking performed on a laboratory-scale tribometer. At the same time, a possible correlation between theoxidation process and emissivity on the disk surface during cooling time is investigated. Sample and diskused in the tests are from a commercial available brake car. Procedure includes changes in the coolingtimes, where 4 different conditions are experienced: 18s, 90s, 600s and 24h. Friction curves revealdifferences between the results obtained with 18s, 90s and 600s. Likewise, when a cooling time of 24h isused, the first stop shows a considerable reduction in the coefficient of friction. It was not possible to find outthe reason for this effect since relationship between friction and oxidation degree, verified by means ofemissivity on the disc surface, could not be encountered

Measurement of the WW Boson Mass

A measurement of the mass of the $W$ boson is presented based on a sample of 5982 $W \rightarrow e \nu$ decays observed in $p\overline{p}$ collisions at $\sqrt{s}$ = 1.8~TeV with the D\O\ detector during the 1992--1993 run. From a fit to the transverse mass spectrum, combined with measurements of the $Z$ boson mass, the $W$ boson mass is measured to be $M_W = 80.350 \pm 0.140 (stat.) \pm 0.165 (syst.) \pm 0.160 (scale) GeV/c^2$.Comment: 12 pages, LaTex, style Revtex, including 3 postscript figures (submitted to PRL

The Azimuthal Decorrelation of Jets Widely Separated in Rapidity

This study reports the first measurement of the azimuthal decorrelation between jets with pseudorapidity separation up to five units. The data were accumulated using the D{\O}detector during the 1992--1993 collider run of the Fermilab Tevatron at $\sqrt{s}=$ 1.8 TeV. These results are compared to next--to--leading order (NLO) QCD predictions and to two leading--log approximations (LLA) where the leading--log terms are resummed to all orders in $\alpha_{\scriptscriptstyle S}$. The final state jets as predicted by NLO QCD show less azimuthal decorrelation than the data. The parton showering LLA Monte Carlo {\small HERWIG} describes the data well; an analytical LLA prediction based on BFKL resummation shows more decorrelation than the data.Comment: 6 pages with 4 figures, all uuencoded and gzippe

Search for W~1Z~2\widetilde{W}_1\widetilde{Z}_2 Production via Trilepton Final States in ppˉp\bar{p} collisions at s=1.8\sqrt{s}=1.8 TeV

We have searched for associated production of the lightest chargino, $\widetilde{W}_1$, and next-to-lightest neutralino, $\widetilde{Z}_2$, of the Minimal Supersymmetric Standard Model in $p\bar{p}$ collisions at \mbox{$\sqrt{s}$ = 1.8 TeV} using the \D0 detector at the Fermilab Tevatron collider. Data corresponding to an integrated luminosity of 12.5$\pm 0.7$ \ipb were examined for events containing three isolated leptons. No evidence for $\widetilde{W}_1\widetilde{Z}_2$ pair production was found. Limits on $\sigma(\widetilde{W}_1\widetilde{Z}_2)$Br$(\widetilde{W}_1\to l\nu\widetilde{Z}_1)$Br$(\widetilde{Z}_2\to l\bar{l}\widetilde{Z}_1)$ are presented.Comment: 17 pages (13 + 1 page table + 3 pages figures). 3 PostScript figures will follow in a UUEncoded, gzip'd, tar file. Text in LaTex format. Submitted to Physical Review Letters. Replace comments - Had to resumbmit version with EPSF directive

Second Generation Leptoquark Search in p\bar{p} Collisions at s\sqrt{s} = 1.8 TeV

We report on a search for second generation leptoquarks with the D\O\ detector at the Fermilab Tevatron $p\bar{p}$ collider at $\sqrt{s}$ = 1.8 TeV. This search is based on 12.7 pb$^{-1}$ of data. Second generation leptoquarks are assumed to be produced in pairs and to decay into a muon and quark with branching ratio $\beta$ or to neutrino and quark with branching ratio $(1-\beta)$. We obtain cross section times branching ratio limits as a function of leptoquark mass and set a lower limit on the leptoquark mass of 111 GeV/c$^{2}$ for $\beta = 1$ and 89 GeV/c$^{2}$ for $\beta = 0.5$ at the 95%\ confidence level.Comment: 18 pages, FERMILAB-PUB-95/185-