Analysis of flux-reversal permanent-magnet machines with different consequent-pole PM topologies

This paper comprehensively studies the electromagnetic performance of flux-reversal permanent-magnet (FRPM) machines with different consequent-pole PM (CPM) topologies. Four CPM topologies are first introduced and classified by different numbers of PM pieces and PM locations on stator teeth. Then, the distribution and working harmonics of air-gap flux density of each CPM topology are analyzed and compared, from which the CPM topology with the highest torque density is identified. The influence of critical design parameters on machine performance is also parametrically investigated. By comparing the torque performance of CPM topologies with their surface-mounted PM counterparts, the advantages of CPM topologies, i.e., torque improvement and magnet volume reduction, are clearly revealed. Four FRPM prototypes are manufactured and tested to verify the analyses

Influence of stator and rotor pole number combinations on the electromagnetic performance of stator slot-opening PM hybrid-excited machine

A new type of three-phase stator hybrid excited machine with permanent magnets (PMs) located at the slot openings of field winding slots is presented in this paper. It has the advantage of good flux regulation capability due to the field excitation. The machines with different stator/rotor pole combinations, i.e., 6-stator pole and 7-/8-/10-/11-/13-/14-rotor poles, have been comparatively investigated in terms of the open-circuit and on-load characteristics, as well as the influence of dc current and the unbalanced magnetic forces. The 2-D finite element analysis (FEA) has been employed for analysis and optimization of the machines together with experimental validation

A high-power factor Vernier machine with coil pitch of two slot pitches

In this paper, an 18-slot/26-pole vernier permanent magnet synchronous machine (VPMSM) with coil pitch of two slot pitches is proposed based on a nine-slot/18-flux-modulation-pole/26-pole VPMSM with concentrated tooth-coil windings. Compared with the original VPMSM, the number of slots is doubled and the phase winding connection is adjusted to reduce the space harmonic content, the phase inductance, and hence, improve the power factor. This paper shows that the proposed VPMSM increases power factor from 0.73 to 0.95 with better torque and flux-weakening capability. Moreover, a series of VPMSMs with high-power factor is proposed from the same design principle and given design guidelines

Studies of the electric dipole transitions of deformed rare-earth nuclei

Spectrum and electric dipole transition rates and relative intensities in $^{152-154}$Sm, $^{156-160}$Gd, $^{160-162}$Dy are studied in the framework of the interacting boson model with s,p,d,f bosons. It is found that E1 transition data among the low-lying levels are in good agreement with the SU(3) dynamical symmetry of the spdf interacting boson model proposed by Engel and Iachello to describe collective rotation with octupole vibration. These results show that these nuclei have SU(3) dynamic symmetry to a good approximation. Also in this work many algebraic expressions for electric dipole transitions in the SU(3) limit of the spdf-IBM have been obtained. These formulae together with the formulae given previously exhaust nearly all the E1 transitions for low-lying negative parity states. They are useful in analyzing experimental data.Comment: 26 pages, 1 figur

Influence of magnetic saturation and rotor eccentricity on back EMF of novel hybrid-excited stator slot opening permanent magnet machine

This paper introduces a novel hybrid-excited stator slot opening permanent magnet (PM) machine (HSSPMM). The operation principle of the machine is described and the effects of rotor eccentricity and magnetic saturation due to PMs on electromagnetic performance, with particular emphasis on back electromotive force (EMF), are analyzed by finite element method (FEM). It shows that different from the conventional PM machines, the open-circuit back EMF in this novel HSSPMM should be zero but may become non-zero if significant magnetic saturation exists, and furthermore, the rotor eccentricity has a detrimental effect on the waveforms, amplitudes, and symmetries of three-phase back EMFs, as confirmed by FEM and tests

Calculation of the γ-TiAl Lattice Resistance

The dislocation width and lattice resistance (Peierls stress) of a γ-TiAl alloy are calculated by the density ratio method. The lattice resistance is shown to decrease with the dislocation width. The relationship between the Peierls stress and dislocation width variation is defined by theoretical derivation. The yield stress is negatively correlated with the shear stress of the material. It can become a useful tool for choosing an appropriate shear stress under deformation.Методом отношения плотностей рассчитаны ширина дислокации и сопротивление решетки (напряжение Пайерлса). Результаты показывают, что сопротивление решетки уменьшается с увеличением ширины дислокации. Путем расчета получена зависимость между напряжением Пайерлса и дислокационным упрочнением, свидетельствующая о том, что предел текучести отрицательно коррелирует с напряжением сдвига материала. Поэтому она может дать полезную информацию для выбора соответствующего напряжения сдвига в процессе растяжения.Методом відносини щільностей розраховані ширина дислокації і опір решітки (напруження Пайерлса). Результати показують, що опір решітки зменшується зі збільшенням ширини дислокації. Шляхом розрахунку отримана залежність між напруженням Пайерлса і дислокаційним зміцненням, яка свідчить про те, що межа плинності негативно корелює з напруженням зсуву матеріалу. Тому вона може дати корисну інформацію для вибору відповідного напруження зсуву в процесі розтягування

Phenomenological Analysis of B->PP Decays with QCD Factorization

In this paper, we study nonleptonic charmless B decays to two light pseudoscalar mesons within the frame of QCD factorization, including the contributions from the chirally enhanced power corrections and weak annihilation. Predictions for the CP-averaged branching ratios and CP-violating asymmetries are given. Within the reasonable range of the parameters, we find that our predictions for the branching ratios of B -> PP are consistent with the present experimental data. But because of the logarithmic divergences at the endpoints in the hard spectator scatterings and weak annihilation, there are still large uncertainties in these predictions.Comment: 34 pages, 5 figures. to appear in PR

The quantum cryptographic switch

We illustrate using a quantum system the principle of a cryptographic switch, in which a third party (Charlie) can control to a continuously varying degree the amount of information the receiver (Bob) receives, after the sender (Alice) has sent her information. Suppose Charlie transmits a Bell state to Alice and Bob. Alice uses dense coding to transmit two bits to Bob. Only if the 2-bit information corresponding to choice of Bell state is made available by Charlie to Bob can the latter recover Alice's information. By varying the information he gives, Charlie can continuously vary the information recovered by Bob. The performance of the protocol subjected to the squeezed generalized amplitude damping channel is considered. We also present a number of practical situations where a cryptographic switch would be of use.Comment: 7 pages, 4 Figure

Quasiparticle Scattering Interference in High Temperature Superconductors

We propose that the energy-dependent spatial modulation of the local density of states seen by Hoffman, et al [hoff2] is due to the scattering interference of quasiparticles. In this paper we present the general theoretical basis for such an interpretation and lay out the underlying assumptions. As an example, we perform exact T-matrix calculation for the scattering due to a single impurity. The results of this calculation is used to check the assumptions, and demonstrate that quasiparticle scattering interference can indeed produce patterns similar to those observed in Ref. [hoff2].Comment: RevTex4 twocolumn, 4 pages, 3 figures. Figs.2-3 virtually embedded (bacause of too big size) while jpg files available in the postscript/source package. Further polishe

Long-distant contribution and χc1\chi_{c1} radiative decays to light vector meson

The discrepancy between the PQCD calculation and the CLEO data for $\chi_{c1}\to \gamma V$ ($V=\rho^0,\,\omega,\,\phi$) stimulates our interest in exploring extra mechanism of $\chi_{c1}$ decay. In this work, we apply an important non-perturbative QCD effect, i.e., hadronic loop mechanism, to study $\chi_{c1}\to \gamma V$ radiative decay. Our numerical result shows that the theoretical results including the hadronic loop contribution and the PQCD calculation of $\chi_{c1}\to \gamma V$ are consistent with the corresponding CLEO data of $\chi_{c1}\to \gamma V$. We expect further experimental measurement of $\chi_{c1}\to \gamma V$ at BES-III, which will be helpful to test the hadronic loop effect on $\chi_{c1}$ decay.Comment: 7 pages, 2 figures. Accepted for publication in Eur. Phys. J.