Three-phase modular permanent magnet brushless machine for torque boosting on a downsized ICE vehicle

The paper describes a relatively new topology of 3-phase permanent magnet (PM) brushless machine, which offers a number of significant advantages over conventional PM brushless machines for automotive applications, such as electrical torque boosting at low engine speeds for vehicles equipped with downsized internal combustion engine (ICEs). The relative merits of feasible slot/pole number combinations for the proposed 3-phase modular PM brushless ac machine are discussed, and an analytical method for establishing the open-circuit and armature reaction magnetic field distributions when such a machine is equipped with a surface-mounted magnet rotor is presented. The results allow the prediction of the torque, the phase emf, and the self- and mutual winding inductances in closed forms, and provide a basis for comparative studies, design optimization and machine dynamic modeling. However, a more robust machine, in terms of improved containment of the magnets, results when the magnets are buried inside the rotor, which, since it introduces a reluctance torque, also serves to reduce the back-emf, the iron loss and the inverter voltage rating. The performance of a modular PM brushless machine equipped with an interior magnet rotor is demonstrated by measurements on a 22-pole/24-slot prototype torque boosting machine

Rotor eddy-current loss in permanent magnet brushless machines

This paper presents an analysis of the rotor eddy-current loss in modular and conventional topologies of permanent magnet brushless machine. The loss is evaluated both analytically and by time-stepped finite-element analysis, and it is shown that it can be significant in both machine topologies. It is also shown that the loss can be reduced significantly by segmenting the magnets

Numerical simulation of wave propagation by modified mild-slope equation

Variational principle is applied to derive a kind of modified mild-slope equation, which considers the first order derivative square term and the second order curvature effect of the topogr-aphy, this equation has higher precision in simulating wave propagation in the rapid changing sea-bed than original modified mild-slope equation. The capability of this model is validated by labor-atory experiment data; the results show that modified mild-slope equation can simulate wave prop-agation effectively in large-scale water area

Integrated filtering-antenna with controllable frequency bandwidth

An integrated design of a band-pass filter and a patch antenna is proposed in this paper by using an aperture coupled structure. Traditionally, the microwave filter and antenna are designed separately using 50 Ohm interface and then connected by transmission lines, which lead to a large size and more loss. Here, the antenna and microwave filter are directly integrated without a 50 Ohm interface between them. Compared with the traditional cascade designing, the co-design of filter and antenna has a more compact size, simpler configuration, improved frequency selectivity and higher system efficiency. The frequency bandwidth also can be controlled by adjusting the dimension of the coupling aperture in the ground. The measured results agree very well with the simulations, showing the filtering-antenna has good performance in impedance matching, radiation pattern and antenna gain

Characteristics and Sensing Properties of the La1-xNdxCo0.3Fe0.7O3 System for CO Gas Sensors

A series of nanostructured La1-xNdxCo0.3Fe0.7O3 perovskite-type (x ranging from 0 to 1) were prepared using the co-precipitation method. CO gas sensing properties of La1-xNdxCo0.3Fe0.7O3 sensors were performed. La0.7Nd0.3Co0.3Fe0.7O3 sensor showed the highest response at 250 °C (S=52.8)

Vanishing Viscous Limits for 3D Navier-Stokes Equations with A Navier-Slip Boundary Condition

In this paper, we investigate the vanishing viscosity limit for solutions to the Navier-Stokes equations with a Navier slip boundary condition on general compact and smooth domains in $\mathbf{R}^3$. We first obtain the higher order regularity estimates for the solutions to Prandtl's equation boundary layers. Furthermore, we prove that the strong solution to Navier-Stokes equations converges to the Eulerian one in $C([0,T];H^1(\Omega))$ and L^\infty((0,T)\times\o), where $T$ is independent of the viscosity, provided that initial velocity is regular enough. Furthermore, rates of convergence are obtained also.Comment: 45page

Dynamic and Postdeformation Recrystallization of Nuclear-Grade 316LN Stainless Steel

Nuclear-grade 316LN stainless steel was subjected to single and double compressions at 1173–1473 K and strain rates of 0.01–10 s⁻¹. The dynamic and postdeformation recrystallization was investigated through analysis of the stress–strain curves and microstructure evolution. The thermal deformation equation and the quantitative relationships between the critical stress for the initiation of dynamic recrystallization and the Zener–Hollomon parameter, Z, and between the dynamic recrystallization grain size D and Z were derived. Dynamic recrystallization developed through an ordinary mechanism at low Z values and through a necklace mechanism at high Z values, with a critical Z value of about 3.6 10¹⁶ . At 1273–1473 K, softening of 316LN stainless steel after deformation was characterized by an Avrami-type equation, where the Avrami parameter, n, has no appreciable temperature dependence, and an average value of n and the activation energy, Qrex , were 0.68 and 129 kJ/mol, respectively.Нержавеющая сталь 316LN ядерного класса подвергалась одно- и двукратному сжатию при 1173...1473 К и скорости деформации 0,01...10 с⁻¹. Динамическая и постдеформационная рекристаллизация изучалась с помощью анализа зависимости деформации от напряжения и развития микроструктуры. Были выведены уравнение тепловой деформации и количественные зависимости между критическим напряжением инициирования динамической рекристаллизации и параметром Зенера Холломона Z, а также между размером зерна D при динамической рекристаллизации и Z. Динамическая рекристаллизация развивалась по обычному механизму при низких значениях Z и по механизму ожерелья при высоких значениях Z, при критическом значении Z примерно 3 6 10¹⁶. При 1273...1473 К разупрочнение нержавеющей стали 316LN после деформирования описывается уравнением Аврами, где параметр Аврами n не проявляет выраженной температурной зависимости, а его среднее значение и энергия активации Qrex составляют 0,68 и 129 кДж/моль соответственно

Kondo spin liquid and magnetically long-range ordered states in the Kondo necklace model

A simplified version of the symmetric Kondo lattice model, the Kondo necklace model, is studied by using a representation of impurity and conduction electron spins in terms of local Kondo singlet and triplet operators. Within a mean field theory, a spin gap always appears in the spin triplet excitation spectrum in 1D, leading to a Kondo spin liquid state for any finite values of coupling strength $t/J$ (with $t$ as hopping and $J$ as exchange); in 2D and 3D cubic lattices the spin gaps are found to vanish continuously around $(t/J)_c\approx 0.70$ and $(t/J)_c\approx 0.38$, respectively, where quantum phase transitions occur and the Kondo spin liquid state changes into an antiferromagnetically long-range ordered state. These results are in agreement with variational Monte Carlo, higher-order series expansion, and recent quantum Monte Carlo calculations for the symmetric Kondo lattice modelComment: Revtex, four pages, three figures; to be published in Physical Review B1, 1 July (2000

Finite temperature properties of the 2D Kondo lattice model

Using recently developed Lanczos technique we study finite-temperature properties of the 2D Kondo lattice model at various fillings of the conduction band. At half filling the quasiparticle gap governs physical properties of the chemical potential and the charge susceptibility at small temperatures. In the intermediate coupling regime quasiparticle gap scales approximately linearly with Kondo coupling. Temperature dependence of the spin susceptibility reveals the existence of two different temperature scales. A spin gap in the intermediate regime leads to exponential drop of the spin susceptibility at low temperatures. Unusual scaling of spin susceptibility is found for temperatures above 0.6 J. Charge susceptibility at finite doping reveals existence of heavy quasiparticles. A new low energy scale is found at finite doping.Comment: REVTeX, 7 pages, 7 figure