Two-spin relaxation of P-dimers in Silicon

We study two-electron singlet-triplet relaxation of donor-bound electrons in Silicon. Hyperfine interaction of the electrons with the phosphorus (P) nuclei, in combination with the electron-phonon interaction, lead to relaxation of the triplet states. Within the Heitler-London and effective mass approximations, we calculate the triplet relaxation rates in the presence of an applied magnetic field. This relaxation mechanism affects the resonance peaks in current Electron Spin Resonance (ESR) experiments on P-dimers. Moreover, the estimated time scales for the spin decay put an upper bound on the gate pulses needed to perform fault-tolerant two-qubit operations in donor-spin-based quantum computers (QCs).Comment: 3 figures, 1 tabl

Discharge rate of cryogens in microgravity - What ground based experimentation cannot resolve

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76407/1/AIAA-1991-3545-390.pd

Transient cryogenic liquid discharge in normal and micro-gravity

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76393/1/AIAA-1991-486-786.pd

Development of a Portable Device for Thermoelectrical Power Measurement—Application to the Inspection of Duplex Stainless Steel Components

Some cast components of the primary loop of French Pressurized Water Reactors are made of cast duplex stainless steels. The mechanical characteristics of these components, working in the temperature range from 285°C to 325°C, may be altered by thermal aging : the hardness of the materials increases whereas its toughness decreases with aging time and temperature. The metallurgical explanation of this phenomena is the unmixing of the ferritic Fe-Cr-Ni solid solution by spinodal decomposition and the precipitation of intermetallic G-phase particles rich in nickel and silicium [1]

Modelling radiative heat transfer in packed beds

A comprehensive approach for modelling dependent radiative heat transfer in beds of large (geometric range) spherical particles is presented. Such a system of large spheres lies in the dependent range even for large porosities. We show that the dependent properties for a bed of opaque spheres can be obtained from their independent properties by scaling the optical thickness while leaving the albedo and the phase function unchanged. The scaling factor is found to depend mainly on the porosity and is almost independent of the emissivity. We show that such a simple scaling for non-opaque particles is not feasible. The transparent and semi-transparent particles are treated by allowing for the displacement across an optical thickness (because of transmission through a particle) while solving the equation of radiative transfer. When combined with the scaling approach, this results in a powerful method of solution called the dependence included discrete ordinates method (DIDOM). The results obtained from the DIDOM give good agreement with the results obtained from the Monte Carlo method.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30032/1/0000400.pd

Effect of solid conductivity on radiative heat transfer in packed beds

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31242/1/0000148.pd

Independent theory versus direct simulation of radiation heat transfer in packed beds

Radiation heat transfer in packed beds of relatively large spherical particles is considered. The common practice is to follow the theory of independent scattering as long as C/[lambda]/s > 0.5, where C is the average interparticle clearance and[lambda] the wavelength. The single particle properties are related to the radiative properties of the bed by volume averaging. The equation of transfer is then solved by an approximate method such as the method of discrete ordinales or the two-flux method. In this study, the Monte Carlo method is used to examine the thermal radiative transfer through packed beds of large (geometric range) particles. Opaque, semi-transparent and emitting particles are considered. The results are compared to the independent theory and to the available experimental results, and they indicate that the independent theory fails even when this C/[lambda] criterion is satisfied. The success of independent theory in systems with low porosities, noted by previous researchers, is shown to be either a special ease existing only for a small range of the optical properties or arising due to some unjustifiable assumptions. For the same radiative particle properties, the deviation from the independent theory is shown to increase with decrease in the porosity. This deviation can be significant even for porosities as high as 0.935.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29077/1/0000112.pd

The stability of lidocaine and epinephrine solutions exposed to electric current and comparative administration rates of the two drugs into pig bladder wall.

Intravesical electromotive administration of local anesthetics is clinically successful but electrochemistry, cost and effectiveness limit the choice of drugs to diluted lidocaine HCl 4% mixed with epinephrine. These studies address the stability of lidocaine and epinephrine both over time and when exposed to electric current, i.e. transport rates with passive diffusion and electromotive administration. The drug mixture used was 50 ml lidocaine 4%, 50 ml H2O and 1 ml epinephrine 1/1000. For stability, the solution was placed either in bowls for 7 days or in a two chamber cell with the donor compartment (drugs) separated from the receptor compartment (NaCl solution) by a viable pig bladder wall. This was subjected to 30 mA for 45 min. Stability was measured with mass spectrometry. The cell was also used to determine transport rates with passive diffusion and currents of 20 mA and 30 mA, over 20, 30 and 45 min. Drug measurements in both compartments and bladder were made with HPLC. Lidocaine remained stable throughout the 7 days, epinephrine on day 1 only and both drugs were stable with 30 mA for 45 min. Comparing 20 mA and 30 mA with passive diffusion, there were significant differences in 6/6 donor compartment lidocaine levels, 4/6 receptor compartment levels and 6/6 bladder tissue levels and also in 6/6 epinephrine donor levels and 6/6 tissue levels. The combination lidocaine and epinephrine remains stable for 1 day and when exposed to 30 mA for 45 min. Electric current accelerates the transport of lidocaine and epinephrine

Quasi two-level PWM operation of a nine-arm modular multilevel converter for six-phase medium-voltage motor drives

This paper proposes a hybrid converter for medium-voltage six-phase machine drive systems that mixes the operation of a traditional two-level voltage-source inverter and the modular multilevel converter (MMC) to enable operation over a wide frequency range. Topologically, the proposed converter consists of nine arms resembling two sets of three-phase MMCs with three common arms, yielding a nine-arm MMC with a 25% reduction in the number of employed arms compared to a traditional dual three-phase MMC. The multilevel property of a standard MMC is emulated in the proposed converter, however on a two-level basis, resulting in a stepped two-level output voltage waveform. The proposed converter has a reduced footprint with advantages of small voltage steps, modular structure, and ease of scalability. Further, it is able to drive high-power six-phase machines within low operating frequencies at the rated torque. The operating principle of the converter is elaborated, and its modulation scheme is discussed. The features of the proposed converter are verified through simulations and experimentally