A novel topology of high-speed SRM for high-performance traction applications

A novel topology of high-speed Switched Reluctance Machine (SRM) for high-performance traction applications is presented in this article. The target application, a Hybrid Electric Vehicle (HEV) in the sport segment poses very demanding specifications on the power and torque density of the electric traction machine. After evaluating multiple alternatives, the topology proposed is a 2-phase axial flux machine featuring both segmented twin rotors and a segmented stator core. Electromagnetic, thermal and mechanical models of the proposed topology are developed and subsequently integrated in an overall optimisation algorithm in order to find the optimal geometry for the application. Special focus is laid on the thermal management of the machine, due to the tough thermal conditions resulting from the high frequency, high current and highly saturated operation. Some experimental results are also included in order to validate the modelling and simulation results

Comparison of capsule-mixed versus hand-mixed glass ionomer cements Part II: Porosity

Glass ionomer restorative cements (GIC) are routinely used in dental practice. During mixing, air incorporation may lead to higher porosity with subsequent weakening of the cement. The degree of porosity will determine whether capsule-mixed or hand-mixed GIC are mechanically stronger for clinical use. To compare the porosity of four commercially available dental glass ionomer cements, supplied in both hand mix and capsule-mix formulations, by evaluating number of voids (%), total volume of voids (mm3 ) and volume percentage of voids (%). Eighty samples were manufactured from hand-mixed GIC: Riva Self Cure; Fuji IX GP ; Ketac Universal, Ketac Molar Easymix, and equivalent capsule-mixed GIC: Riva Self Cure; Fuji IX GP ; Ketac Universal Aplicap and Ketac Molar Aplicap. Micro-CT scanning was used to evaluate porosity. The number of voids (mm3 ), total volume of voids (mm3 ) and the volume percentage of voids (%) were calculated

Cost of critical care in South Africa

No Abstract

Closed traction reduction of cervical spine facet dislocations: Compelled by law

Background. Following a 2015 ruling, the South African (SA) Constitutional Court obligates closed reduction of cervical facet dislocations sustained through low-energy injury mechanisms, within 4 hours of injury. Closed traction reduction of cervical facet dislocations requires specific equipment and expertise, which have limited availability in SA.Objectives. To review the time delays, delaying factors and success rate of closed reductions of cervical facet dislocations in a tertiary-level orthopaedic department and training facility, and to consider the feasibility of such a reduction within 4 hours after injury.Methods. The clinical records and imaging screens of patients presenting with cervical facet dislocations to an academic training hospital between November 2008 and March 2016 were retrospectively reviewed, with specific attention to demographic information, mechanism of injury, time delays from injury to treatment and factors resulting in delay, as well as the success rate in closed cervical reduction.Results. Ninety-one patients with cervical dislocation presented during the study period, of whom 69 were included for further review. The mean age at presentation was 37.6 (range 18 - 65) years. Successful reduction was achieved in 71% (n=49) of cases, with a median delay time from injury to reduction of 26 (interquartile range (IQR) 19.50 - 31.75) hours. Only 1 patient of 69 patients received successful reduction within 6 hours after injury. Neurological improvement was noticed in 5 of 53 patients with neurological deficit – after successful reduction. Two patients improved with two American Spinal Injury Association (ASIA) grades (from A to C), and 2 improved with one ASIA grade (from A to B and D to E).Conclusions. Successful reduction of a cervical facet dislocation within 4 hours presents a challenge to healthcare infrastructure globally. The relative scarcity of this type of injury (91 cases during 8 years in a tertiary referral hospital) prevents district-level clinicians from readily acquiring a level of experience to confidently perform closed reduction of these injuries, unless very specific training and support are provided towards this end