Permanent Magnet Motor Torsional Resonance Noise Reduction by Rotor Skew Phase Adjustment

Hybrid Vehicles (HEVs) and Electric Vehicles (EVs) improve drive efficiency and reduce CO₂ emissions by regenerative braking and operating the engine under optimum conditions. It is desirable to decrease the motor size and increase the maximum torque to minimize driving units. For these purposes, motors employing permanent magnets are now commonly used. The motor driving systems of HEVs and EVs must operate over variable speed ranges of up to 1:5. Over this large range, smooth, silent operation is desirable and important. The skew method is often adopted to ensure a smooth start and stop and silent operation by reducing torque ripple. However, this method possibly causes noise and motor vibration. This paper describes the mechanism of torsional resonance noise and vibrations arising from the skew method and a countermeasure to decrease them by optimizing the skew phase distribution on the rotating axis.     

Neuronal mechanisms of respiratory rhythm generation: an approach using in vitro preparation

The respiratory network in the ventrolateral medulla of the brainstem-spinal cord preparation from newborn rat involves pre-inspiratory (Pre-I) neurons, three types of inspiratory (Insp I, II, III) neurons and two types of expiratory (Exp-i, Exp-p-i) neurons as major subtypes, which were classified according to patterns of postsynaptic potentials. The neuronal respiratory-related membrane potential fluctuations of these cells indicate at least four distinguishable phases of the in vitro respiratory cycle: pre-inspiratory, inspiratory, post-inspiratory (E1), and late-expiratory (E2). A current hypothesis for the central pattern generator of respiration proposed by our group is that Pre-I neurons in the rostral ventrolateral medulla, with intrinsic burster properties, produce the primary respiration rhythm. This rhythm triggers an inspiratory pattern generator composed of Insp neurons in the rostral and caudal ventrolateral medulla. Respiratory neurons possess several types of ionic channels which are involved in the generation of rhythm and burst pattern. Particularly, P-type Ca2+ channels and TTX-sensitive persistent Na+ channels are postulated to contribute to the intrinsic burst generation of Pre-I neurons. N-type Ca2+ channels may be involved in the maintenance and termination of inspiratory burst activity via the activation of Ca2(+)-dependent K+ channels. Respiratory neuron networks in this preparation were compared with those of different in vitro preparations, like rhythmic slices or perfused brainstems and of adult mammals in vivo. Many types of synaptic connections among respiratory neurons in adult mammals were also found in the (rostral) ventrolateral medulla of a brainstem-spinal cord preparation from newborn rat. The characteristics of the inspiratory burst pattern and inspiratory off switch mechanisms in newborn rat preparations might be explained by insufficient inhibitory (or excitatory) synaptic inputs to the inspiratory pattern generator due to an immature neuron network and/or deafferentiation.     

Biofilm formation of Staphylococcus aureus strains isolated from impetigo and furuncle: role of fibrinogen and fibrin

Effective utilization of spiral computed tomography (CT) technology in imaging of the thorax requires an understanding of technical parameters that affect image and scan quality. This article discusses how operator-controlled scan parameters can be optimized to achieve diagnostic and cost-effective examinations appropriate for daily clinical practice.     

Enhanced anaerobic biodegradation of polychlorinated biphenyls in burnt soil culture

Anaerobic microbial degradation of polychlorinated biphenyls (PCBs) in Kanechlors-300 and -400 was enhanced significantly by adding burnt soil originally obtained from an uncontaminated paddy soil to the microbial culture. The maximum PCB-degrading activity was 0.49 nmol-Cl/ml-culture/day (238 ng-total-PCBs/ml-culture/day), where the degradation was observed in most of the congeners in Kanechlors-300 and -400: not only in meta- and para-substituted congeners but also ortho-substituted congeners. The degradation of PCBs occurred during the increase in the microbial population with acetate as the main electron donor. The ratio between the consumption of electron donors and the dechlorination of PCBs was revealed to be 93.9 nmol-Cl/mmol-e-donor, which is also the dechlorination efficiency over 56 d of incubation. The addition of acetate and lactate several times into the culture rejuvenated the activity.     

RedOx study of anode-supported solid oxide fuel cell

The common technology for solid oxide fuel cells (SOFC) is based on a cermet (ceramic-metal composite) anode of nickel with yttria stabilized zirconia (YSZ), often used as the supporting structure. One of the main limitations of this technology is the tolerance of the anode towards reduction and oxidation (“RedOx”) cycles.In this study, two techniques are used to quantify the anode expansion after a RedOx cycle of the nickel at different temperatures. The first method considers the anode expansion above the electrolyte fracture limit by measuring the crack width in the electrolyte layer. In the second method, the anode porosity is measured using scanning electron microscopy (SEM) image quantification. The same measurement techniques are used to quantify anode expansion after consecutive RedOx cycles at constant temperature.The quantification technique is then applied to cells tested in real stack conditions. The cell corners can undergo several RedOx cycles depending on stack design and fuel utilization. The study of such zones allows estimating the number of cycles that the anode experienced locally.     

Simulation of thermal stresses in anode-supported solid oxide fuel cell stacks. Part II: Loss of gas-tightness, electrical contact and thermal buckling

Structural stability issues in planar solid oxide fuel cells arise from the mismatch between the coefficients of thermal expansion of the components. The stress state at operating temperature is the superposition of several contributions, which differ depending on the component. First, the cells accumulate residual stresses due to the sintering phase during the manufacturing process. Further, the load applied during assembly of the stack to ensure electric contact and flatten the cells prevents a completely stress-free expansion of each component during the heat-up. Finally, thermal gradients cause additional stresses in operation.The temperature profile generated by a thermo-electrochemical model implemented in an equation-oriented process modelling tool (gPROMS) was imported into finite-element software (ABAQUS) to calculate the distribution of stress and contact pressure on all components of a standard solid oxide fuel cell repeat unit.The different layers of the cell in exception of the cathode, i.e. anode, electrolyte and compensating layer were considered in the analysis to account for the cell curvature. Both steady-state and dynamic simulations were performed, with an emphasis on the cycling of the electrical load. The study includes two different types of cell, operation under both thermal partial oxidation and internal steam-methane reforming and two different initial thicknesses of the air and fuel compressive sealing gaskets.The results generated by the models are presented in two papers: Part I focuses on cell cracking. In the present paper, Part II, the occurrences of loss of gas-tightness in the compressive gaskets and/or electrical contact in the gas diffusion layer were identified. In addition, the dependence on temperature of both coefficients of thermal expansion and Young's modulus of the metallic interconnect (MIC) were implemented in the finite-element model to compute the plastic deformation, while the possibilities of thermal buckling were analysed in a dedicated and separate model.The value of the minimum stable thickness of the MIC is large, even though significantly affected by the operating conditions. This phenomenon prevents any unconsidered decrease of the thickness to reduce the thermal inertia of the stack. Thermal gradients and the shape of the temperature profile during operation induce significant decreases of the contact pressure on the gaskets near the fuel manifold, at the inlet or outlet, depending on the flow configuration. On the contrary, the electrical contact was ensured independently of the operating point and history, even though plastic strain developed in the gas diffusion layer.     

Requirement of CD4 T cells for skin graft rejection against thymus leukemia (TL) antigen and multiple epitopes on the TL molecule recognized by CD4 T cells

Two HPLC assays were developed and validated for simultaneous quantitation of two sulfate metabolites, PD 163637 (VI) and PD 163639 (VIII), of an investigational antipsychotic drug CI-1007 (I) in monkey plasma and urine. VI and VIII were identified as major metabolites in monkey plasma, and both were excreted in urine. Monkey plasma samples were directly injected after deproteinization, and urine samples were analyzed after a clean-up procedure using methyl-tert.-butyl ether. Liquid chromatographic separation was achieved on a Zorbax RX C8 analytical column using gradient elution. Column effluent was monitored using fluorescence detection with excitation and emission wavelengths of 254 and 330 nm, respectively. Minimum quantitation limit was 50 ng/ml in plasma and 100 ng/ml in urine. Linearity was demonstrated up to 3000 ng/ml in plasma and urine. Recoveries of the analytes from plasma and urine were greater than 85%. The assay has been applied to the determination of VI and VIII in plasma and urine samples from monkeys receiving oral administration of I.     

Properties of Bi-doped PbTe epitaxial layers and pn junction diodes grown by TDM-CVP

Effects of Bi-doping in PbTe liquid-phase epitaxial layers grown by the TDM-CVP have been investigated. For Bi concentration in the solution, x_Bi, lower than 0.2 at.%, Hall mobility is low. In contrast, for x_Bi>0.2 at.%, Hall mobility is high, while carrier concentration is in the range 10¹⁷ cm⁻³. However, ICP emission analysis shows that, for x_Bi=1.0 at.%, Bi concentration in epitaxial layer is N_Bi=2.3–2.7×10¹⁹ cm⁻³.These results indicate that Bi behaves not only as a donor but also as an acceptor; the nearest neighbor or very near DA pairs are formed. Carrier concentration for Bi-doped layers takes a minimum value at a Te vapor pressure of 2.2×10⁻⁵ Torr for growth temperature 470°C, which is coincident with that of the undoped PbTe. And broad contact pn junctions with highly Bi-doped layers easily cause laser emission compared to undoped junctions. The result suggests that the nearest lattice site Bi–Bi DA pairs behave as strong radiative centers in PbTe.     

Determination of acid strength of solid superacids by temperature programmed desorption using pyridine

Acid strength of solid superacids was determined by temperature programmed desorption using pyridine. An approximately linear relationship exists between the acid strengths of solid acids determined by the Hammett method and the termination temperature of pyridine desorption. The acid strength of colored superacids versus temperature relationships practically fell on the linear line.