Statistical analysis of the transmission based on the DMPK equation: An application to Pb nano-contacts

The density of the transmission eigenvalues of Pb nano-contacts has been estimated recently in mechanically controllable break-junction experiments. Motivated by these experimental analyses, here we study the evolution of the density of the transmission eigenvalues with the disorder strength and the number of channels supported by the ballistic constriction of a quantum point contact in the framework of the Dorokhov-Mello-Pereyra-Kumar equation. We find that the transmission density evolves rapidly into the density in the diffusive metallic regime as the number of channels $N_c$ of the constriction increase. Therefore, the transmission density distribution for a few $N_c$ channels comes close to the known bimodal density distribution in the metallic limit. This is in agreement with the experimental statistical-studies in Pb nano-contacts. For the two analyzed cases, we show that the experimental densities are seen to be well described by the corresponding theoretical results.Comment: 6 pages, 6 figure

Balance torquemeter Patent

Torquemeter for determining magnitude of torque generated by interaction of magnetic dipole between test specimen and ambient magnetic fiel

Supercritical bifurcation of a hula hoop

The motion of a hoop hung on a spinning wire provides an illustrative and pedagogical example of a supercritical bifurcation. Above a certain angular velocity threshold Omega_c, the hoop rises, making an angle theta = (Omega-Omega_c)^(1/2) with the vertical. The equation of motion is derived in the limit of a long massless wire, and the calculated steady states are compared to experimental measurements. This simple experiment is suitable for classroom demonstration, and provides an interesting alternative to the classical experiment of the bead sliding on a rotation hoop.Comment: subm. to Am. J. Phys. (7 figs

Aerodynamics of F1 car side mirror

This study investigates the aerodynamic performance of a Formula 1 carrear view side mirror when the location of its glass is varied inside its frame. Bothexperimental and computational studies have been carried out for a simplifiedtwo-dimensional model of a typical Formula 1 mirror at different Reynoldsnumbers. Experimental results showed strong correlation between the mirror’sglass location and its drag over all investigated Reynolds number range of1.1 × 105 to 2.6 × 105 – as the mirror’s glass is located further inside its frame areduction in the drag is achieved with a maximum of 10%-11%. No change is foundin the mirror’s vortex shedding frequency at all investigated Reynolds numberswhich implies no structural impact of this modification. However thecomputational results obtained using Fluent failed to predict the changes in flowcharacteristics and drag caused by the proposed modification, more calculationsare needed using higher order numerical methods should be performed toinvestigate this phenomenon further to confirm the experimental findings

Analyzing Powers and Spin Correlation Coefficients for p+d Elastic Scattering at 135 and 200 MeV

The proton and deuteron analyzing powers and 10 of the possible 12 spin correlation coefficients have been measured for p+d elastic scattering at proton bombarding energies of 135 and 200 MeV. The results are compared with Faddeev calculations using two different NN potentials. The qualitative features of the extensive data set on the spin dependence in p+d elastic scattering over a wide range of angles presented here are remarkably well explained by two-nucleon force predictions without inclusion of a three-nucleon force. The remaining discrepancies are, in general, not alleviated when theoretical three-nucleon forces are included in the calculations.Comment: 43 pages, 12 figures, accepted for publication by Phys. Rev.

New determination of the mass of the eta meson at COSY-ANKE

A value for the mass of the eta meson has been determined at the COSY-ANKE facility through the measurement of a set of deuteron laboratory beam momenta and associated 3He center-of-mass momenta in the d+p -> 3He+X reaction. The eta was then identified by the missing-mass peak and the production threshold determined. The individual beam momenta were fixed with a relative precision of 3 x 10^-5 for values around 3 GeV/c by using a polarized deuteron beam and inducing an artificial depolarizing spin resonance, which occurs at a well-defined frequency. The final-state momenta in the two-body d+p -> 3He+eta reaction were investigated in detail by studying the size of the 3He momentum ellipse with the forward detection system of the ANKE spectrometer. Final alignment of the spectrometer for this high precision experiment was achieved through a comprehensive study of the 3He final-state momenta as a function of the center-of-mass angles, taking advantage of the full geometrical acceptance. The value obtained for the mass, m(eta)=(547.873 +- 0.005(stat) +- 0.027(syst)) MeV/c^2, is consistent and competitive with other recent measurements, in which the meson was detected through its decay products.Comment: 11 pages, 11 figures, 3 tables, published versio

Reliability evaluation of hermetic dual in-line flat microcircuit packages

The relative strengths and weaknesses of 35 commonly used hermetic flat and dual in-line packages were determined and used to rank each of the packages according to a numerical weighting scheme for package attributes. The list of attributes included desirable features in five major areas: lead and lead seal, body construction, body materials, lid and lid seal, and marking. The metal flat pack and multilayer integral ceramic flat pack and DIP received the highest rankings, and the soft glass Cerdip and Cerpak types received the lowest rankings. Loss of package hermeticity due to lead and lid seal problems was found to be the predominant failure mode from the literature/data search. However, environmental test results showed that lead and lid seal failures due to thermal stressing was only a problem with the hard glass (Ceramic) body DIP utilizing a metal lid and/or bottom. Insufficient failure data were generated for the other package types tested to correlate test results with the package ranking