A novel switched reluctance motor drive with optical graphicalprogramming technology

Due to magnetic nonlinearities, switched reluctance motor (SRM) drive control is complicated and normally requires a microprocessor or a digital signal processor. This paper presents a simple and reliable SRM drive using an innovative encoder based on optical graphical programming technology. There is no microprocessor in the drive, no A/D or D/A circuitry, with a drive system that matches the simplicity of the motor construction. It features a simple and effective control capability. Current waveform optimization for the encoder is carried out offline, for high efficiency, and programmed directly into the encoder. Experimental results validate the concept     

Analytical study of the impacts of an SSSC and its power flow controller on torsional interaction

Previous research has shown that a power flow controller based on a static synchronous series compensator (SSSC) can cause torsional interaction with nearby turbine generators. This paper presents further investigations to examine the extent to which such torsional interaction is caused by the resonant characteristics of the SSSC itself, and by the addition of the power controller around the SSSC. The results demonstrate that the power flow controls can directly influence the electromechanical modes of a turbine generator even when there is no electrical resonance caused by the SSSC itself.     

Heat Capacity Setup for Superconducting Bolometer Absorbers below 400 mK

A calorimeter set up with very low heat capacity ( $\sim $ 20 nJ/K at 100 mK) has been designed using commercial Carbon based resistors. This calorimeter is used to determine the heat capacity of small samples of superconducting bolometer absorbers. In particular, we present heat capacity studies of Tin, a bolometer candidate for Neutrinoless Double Beta Decay in $^{124}$ Sn, in the temperature range of 60–400 mK.     

Physical,nutritional and antioxidant properties of Zimbabwean bambara groundnut and effects of processing methods on their chemical properties

This study examined the physical, nutritional and antioxidant properties of popular Zimbabwean bambara groundnut landraces and the effects of different processing methods on their chemical properties. The physical, nutritional and antioxidant properties of grains of the bambara landraces differed significantly with grain type, and the processing methods investigated had varying effects on the chemical properties of the grains. Bambara had significantly lower protein content than the reference common bean. Protein and carbohydrate content of the grains increased upon dehulling, while tannin (approx. 36%), total phenolic content (approx. 83%) and antioxidant activities (approx. 18%) decreased. Roasting alone seemed to have little or no effect on the nutrient content of the grains, while sifting significantly reduced the phenolic content and antioxidant activity of all the dehulled and roasted samples. The results indicate that roasting bambara grains would be a suitable method as it is relatively more conservative of nutrients and antioxidants than the other methods investigated.     

Use of the donor iliac vein to replace the retrohepatic vena cava in pediatric reduced-size liver retransplantation

The authors describe a new technique that used the donor common iliac vein and its bifurcation into the external iliac and internal iliac veins to replace the retrohepatic vena cava; this was used in a recipient who underwent her second reduced-size transplantation (segments II and III). Anastomosis of the donor hepatic vein to the internal iliac vein, with use of this segment of the venous graft to replace the retrohepatic vena cava, is for patients who have had more than one surgical procedure before liver transplantation.     

Reclosing transients in induction machines including the effects ofsaturation of the magnetizing branch and a practical case study

Induction motors make up the majority of the load in many industries. The industry is becoming increasingly aware of the need to ride through short term faults on the power system to improve the system reliability, particularly where motors drive critical loads. This often requires reclosing on the motor before it has reached zero speed. Such reclosures can damage the motor due to excessive current and torque transients. This paper examines the reclosing transients in an induction motor, including the effects of saturation. A practical case study is also presented with speed and back EMF measurements from a 20 HP induction motor driving a mixer in an oil refinery     

Nonattendance at a general hospital psychological clinic in South Africa

Over a 10-yr. period 11.6% of the 3738 patients referred to a general hospital's psychological clinic in South Africa did not attend their first appointments. Patients who had engaged in suicidal behaviours and those with somatoform symptoms were the predominant nonattenders, while those with depressive symptoms had the lowest nonattendance rate.     

The effect of link current ripple on the torque pulsations in a current source inverter-fed induction motor

This paper analyses the effect of link current ripple on the torque pulsations of a current source inverter-fed induction motor. The torque pulsations produced by a ‘pure’ DC link current are compared with those produced by a link current containing both DC and a superimposed ripple. It shows that if the average values of link current in the two cases are the same, the magnitudes of the torque pulsations with and without ripple are approximately equal in the time domain, although the magnitudes of the individual torque harmonics are affected. It also investigates the effects of different inverter frequencies on the torque pulsations.     

Preliminary work on the development of a novel detection method for osteoporosis

Osteoporosis affects both the organic and mineral phases of bone resulting in a decrease in resistance to fracture. Dual x-ray absorptiometry (DEXA) scans are used for diagnosing osteoporosis, which is conventionally characterised by a decrease in mineral density. Unfortunately, some patients who suffer osteoporotic fractures have normal bone density, because both the organic and the mineral phase are affected. However, there are currently no methods of evaluating the health of the organic phase. Patients undergoing treatment for osteoporosis have reported hardening of their fingernails. As the properties of nail and bone may be linked in a comparable, measurable way, this work used both mechanical (nano-indentation) and chemical (Raman spectroscopy) methods to evaluate differences between fingernails sourced from osteoporotic and non-osteoporotic patients. The difference in mean modulus between the nails sourced from the groups was 1.1 GPa. The disulphide bond content of fingernail samples from each group was measured by Raman spectroscopy and disulphide bond content of fingernail was found to be significantly lower in the osteoporotic group. It can be concluded that a relationship between the mechanical and chemical properties of nail and bone may exist in a measurable way. This work has suggested that changes in the organic phase of bone are reflected in similar proteins, such as keratin, from which fingernails are composed. Collagen and keratin are two distinct structural proteins, but they share the need for protein sulphation and disulphide bond formation, via cysteine, for their structural integrity. A disorder of either process should lead to disordered collagen and keratin synthesis.