Performance Comparison between Consequent-Pole and Inset Modular Permanent Magnet Machines

This paper proposes some consequent-pole modular permanent magnet machines with different flux gap widths and slot/pole number combinations. The corresponding inset modular permanent magnet machines having the same magnet volume are also presented for comparison. It has been demonstrated that the output torques of the consequent pole modular machines are always higher than those of the inset modular machines regardless of flux gap widths and slot/pole number combinations. Other electromagnetic performances such as back-EMF, cogging torque, and iron losses, etc. are calculated by 2D FEA software and compared as well. The advantages and disadvantages of consequent and inset modular permanent magnet machines are summarized in this paper

Charmless Bs→PP,PV,VVB_s\to PP, PV, VV Decays Based on the six-quark Effective Hamiltonian with Strong Phase Effects II

We provide a systematic study of charmless $B_s \to PP, PV, VV$ decays ($P$ and $V$ denote pseudoscalar and vector mesons, respectively) based on an approximate six-quark operator effective Hamiltonian from QCD. The calculation of the relevant hard-scattering kernels is carried out, the resulting transition form factors are consistent with the results of QCD sum rule calculations. By taking into account important classes of power corrections involving "chirally-enhanced" terms and the vertex corrections as well as weak annihilation contributions with non-trivial strong phase, we present predictions for the branching ratios and CP asymmetries of $B_s$ decays into PP, PV and VV final states, and also for the corresponding polarization observables in VV final states. It is found that the weak annihilation contributions with non-trivial strong phase have remarkable effects on the observables in the color-suppressed and penguin-dominated decay modes. In addition, we discuss the SU(3) flavor symmetry and show that the symmetry relations are generally respected

Short-term outcomes of Gustilo grade 3A open tibia diaphyseal fractures: intramedullary nail versus external fixation

Background: Open tibial fractures pose a major therapeutic challenge due to the high incidence of postoperative complications. Although Locked Intramedullary (IM) nail and uniplanar External Fixation (EF) are the most common treatment modalities, the superior mode of management remains controversial.Objective: The purpose of this study was to prospectively compare short-term outcomes of patients with Gustilo 3A open tibia shaft fractures treated with IM nail compared to uniplanar EF.Methodology: In this prospective cohort study, adult patients (≥18 years-old) with Gustilo 3A open tibia shaft fractures treated by either intramedullary nail or EF were included. This study was conducted at Muhimbili Orthopaedic Institute, Dar es Salaam, Tanzania for a period of twelve months from March 2013 to February 2014. After enrollment, patients were followed-up at 2, 6, 10, 14, and 18 weeks postoperatively. At these visits, rate of callus formation at fracture site and surgical complications (e.g. infection, limb length discrepancy, malalignment) were assessed.Results: Out of 50 patients enrolled in the study, 26 were treated by IM nail and 24 by external fixation. Twenty-four patients (92.3%) in the IM nail group and 6 (25%) in the external fixation group had callus formation by the 10th week. The mean times to callus formation in the IM nail group and external fixation group were 8.2±2.6 weeks and 14.7±3.3 weeks, respectively (p=0.000). Two (7.7%) patients in the IM nail group and 3 (12.5%) in the external fixation group developed infection (p=0.661). No IM nail patients developed limb length discrepancy. In contrast, to 2 (8.3%) external fixation patients developed limb shortening between 2-3cm. No patients had limb length shortening of >3cm. No malalignment was observed in IM nail patients, but 3 (12.5%) external fixation patients developed malalignment and required reoperation.Conclusion: Interlocking intramedullary nail appears to be a better option for the treatment of Gustilo 3A open tibia shaft fractures as compared to uniplanar external fixation. Advantages of the IM nail include faster rate of callus formation and lower rates of limb length discrepancy and malalignment.Key words: Open tibia fractures, Orthopaedic surgery, Tanzania, Intramedullary nail, External fixatio