The development of a fuzzy controller for tractive effort of a resistor technology locomotive

The application of a rule based fuzzy controller, implementing human skill and experience to control tractive effort of a resistor technology locomotive, is presented. The fuzzy controller aims to smoothly and safely accelerate the train from standstill. The controller provides the operational consistency and feedback functions required for improved protection of the traction motors, locomotives, rails and load. A simulation model for the locomotive and load is included

Some Aspects On Integrated Current Shunts For High Frequency Switching Power Electronic Converters

Abstract: Switched power electronic converters are now able to operate at very high frequencies due to the development in wide band gap high electron mobility transistors (HEMT) such as GaN and SiC power semi-conductor technologies. Measuring current at such high switching frequencies with rise and fall times of a few nanoseconds, requires specialised instruments and a good knowledge of measurement techniques. Current measurement technologies that are readily available are relatively expensive and can add unwanted parasitic impedances to the circuit. This paper investigates some aspects for a few current shunt options that can be integrated into a converter

Morphological variation in the girdled lizard Cordylus mclachlani Mouton 1986

The girdled lizard Cordylus mclachlani, previously known only from the type locality in the south-western Cape, South Africa, was found at several new localities as far north as Nieuwoudtville. The external morphology of the 32 additional specimens thus obtained was investigated to establish the nature of geographical variation. Specimens from the type locality, which lies on the southern periphery of the known distribution range, differ from the rest in the number of suboculars, the shape of the interparietal scale and in the presence of a post-interparietal scale. Because of some overlap in these characters, separate taxonomie status for the specimens outside the type locality is not considered. The diagnostic character set for the species is updated and additional ecological information is supplied

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Symmetrical and asymmetrical stable modes in systems for electronic stator control of asynchronous machines by semiconductor switches

In control systems utilising electronic stator voltage control of induction machines by variation of conduction-angle delay, the flow of currents containing a d.c. component may cause instability. Asymmetric current flow is therefore undesirable, and, under these conditions, the requirements for the triggering command are examined and a solution is proposed

On carrier-frequency gating systems for static switching circuits

Carrier-frequency gating systems for exciting static electronic switches such as thyristors are examined. The effect of the commutation in the output rectifiers during transmission of the carrier wave is to cause an instantaneous drop in the output voltage during commutation. A compensation for the commutation drop by an overlap technique is proposed, and comparative experimental observations presented on two types of systems