Proprioceptive perception of phase variability

Previous work has established that judgments of relative phase variability of 2 visually presented oscillators covary with mean relative phase. Ninety degrees is judged to be more variable than 0° or 180°, independently of the actual level of phase variability. Judged levels of variability also increase at 180°. This pattern of judgments matches the pattern of movement coordination results. Here, participants judged the phase variability of their own finger movements, which they generated by actively tracking a manipulandum moving at 0°, 90°, or 180°, and with 1 of 4 levels of Phase Variability. Judgments covaried as an inverted U-shaped function of mean relative phase. With an increase in frequency, 180° was judged more variable whereas 0° was not. Higher frequency also reduced discrimination of the levels of Phase Variability. This matching of the proprioceptive and visual results, and of both to movement results, supports the hypothesized role of online perception in the coupling of limb movements. Differences in the 2 cases are discussed as due primarily to the different sensitivities of the systems to the information

Integrated multilevel converter and battery management

A cascaded H-bridge multilevel converter is proposed as a BLDC drive incorporating real-time battery management. Intelligent H-bridges are used to monitor battery cells whilst simultaneously increasing their performance by reducing the variation between cells and controlling their discharge profiles

Battery health determination by subspace parameter estimation and sliding mode control for an all-electric Personal Rapid Transit vehicle — the ULTra

The paper describes a real-time adaptive battery modelling methodology for use in an all electric personal rapid transit (PRT) vehicle. Through use of a sliding-mode observer and online subspace parameter estimation, the voltages associated with monitoring the state of charge (SoC) of the battery system are shown to be accurately estimated, even with erroneous initial conditions in both the model and parameters. In this way, problems such as self- discharge during storage of the cells and SoC drift (as usually incurred by coulomb-counting methods due to overcharging or ambient temperature fluctuations) are overcome. Moreover, through online monitoring of the degradation of the estimated parameters, battery ageing (State of Health) can be monitored and, in the case of safety- critical systems, cell failure may be predicted in time to avoid inconvenience to passenger networks. Due to the adaptive nature of the proposed methodology, this system can be implemented over a wide range of operating environments, applications and battery topologies, by adjustment of the underlying state-space model

State-variable modelling of CLL resonant converters

The paper presents the derivation and application of state-variable models to high-order topologies of resonant converters. In particular, a 3rd order CLL resonant circuit is considered with bridge rectification and both a capacitive output filter (voltage output), and an LC output filter (current output). The state-variable model accuracy is verified against component-based simulation packages (Spice) and practical measurements, and it is shown that the resulting models facilitate rapid analysis compared to their integration-based counterparts (Spice, Saber), without the loss of accuracy normally associated with fundamental mode approximation (FMA) techniques. Moreover, unlike FMA, the models correctly predict the resonant peaks associated with harmonic excitation of the tank resonance. Subsequently, it is shown that excitation of the resonant tank by odd harmonics of the input voltage can be utilised to provide overcurrent protection in the event of an output short-circuit. Further, through judicious control of operating frequency, it is shown that 'inductive' zero voltage switching (ZVS) can still be obtained, facilitating reductions in gate-drive switching losses, thereby improving efficiency and thermal management of the supply under fault conditions. Although the results are ultimately generic to other converter counterparts, measured results from two prototype 36 V input, 11-14.4V output, 3rd - order CLL converters are included to practically demonstrate the attributes of the proposed analysis and control schemes

Novel battery model of an all-electric personal rapid transit vehicle to determine state-of-health through subspace parameter estimation and a Kalman Estimator

Abstract--The paper describes a real-time adaptive battery model for use in an all-electric Personal Rapid Transit vehicle. Whilst traditionally, circuit-based models for lead-acid batteries centre on the well-known Randles’ model, here the Randles’ model is mapped to an equivalent circuit, demonstrating improved modelling capabilities and more accurate estimates of circuit parameters when used in Subspace parameter estimation techniques. Combined with Kalman Estimator algorithms, these techniques are demonstrated to correctly identify and converge on voltages associated with the battery State-of-Charge, overcoming problems such as SoC drift (incurred by coulomb-counting methods due to over-charging or ambient temperature fluctuations). Online monitoring of the degradation of these estimated parameters allows battery ageing (State-of-Health) to be assessed and, in safety-critical systems, cell failure may be predicted in time to avoid inconvenience to passenger networks. Due to the adaptive nature of the proposed methodology, this system can be implemented over a wide range of operating environments, applications and battery topologies

Hardware-in-the-loop tuning of a feedback controller for a buck converter using a GA

This paper presents a methodology for tuning a PID-based feedback controller for a buck converter using the ITAE controller performance index. The controller parameters are optimized to ensure that a reasonable transient response can be achieved whilst retaining stable operation. Experimental results demonstrate the versatility of the on-line tuning methodology

Rapid steady-state analysis of CLL resonant power converters

Cyclic averaging techniques are applied to the CLL resonant power converter to provide steady-state converter characteristics for rapid stress analysis. This is shown to facilitate the determination of mode duties and initial conditions through knowledge of the operational modes of the rectifier at various operating frequencies. Comparisons are made with FMA-based cyclic analyses, and Spice simulations, that show, respectively, improved accuracy and vastly improved execution speeds

A three-phase to single-phase matrix converter for high-frequency induction heating

The paper describes a new three-phase to single-phase matrix converter featuring unity input power factor, very low input total harmonic distortion, and soft-switching over the full power range, for high frequency induction heating applications. A variable output pulse density modulation scheme has been proposed for stable operation of the converter, with the notable feature of requiring no on-line calculations for the synthesis of three-phase input current system. Practical issues in realising the converter, viz. line frequency synchronisation and output current circulation, are described. Good agreement between simulation and experimental results confirm the benefits of the proposed converter

The surgical aspects of water and salt metabolism

I. Water and Salt metabolism has been discussed both in their theoretical and in their practical aspects.2. A series of experiments was conducted on normal human subjects to prove or disprove certain conceptions of salt metabolism.3. In general these conceptions were substantiated and, arising from this work the clinical applications are as follows:A. To diminish the mortality and morbidity from operations both water and electrolytes must be given in adequate amounts to restore or maintain normality. Two main types of problem therefore, may confront the surgeon.I. The case which comes under his care with depleted fluids and electrolytes and rules have been given for the restoration of both to normal.2. The case which in hospital after operation loses electrolytes and fluids from vomiting, fistulae, etc. Such a case can be maintained in fluid balance by the application of the rules of water balance enunciated by W. G. Maddock and detailed in this paper. The electrolyte balance can also be maintained by the administration of a volume of 0.9% sodium chloride solution equal to the volume of the abnormal fluid losses (vomitus, drainage from fistulae etc.) without endangering the patient by overloading him with sodium chloride.B. The following table shows the degree of accuracy which results from the application of these rules, and I feel that, although much further work is needed fully to substantiate our claims, the clinical administration of sodium chloride has been placed on a sound basis

Some aspects of the pre and post operative care of surgical patients

The first forty years of the twentieth century have seen greater advances in the science and art of surgery than the whole of preceding time. But, as the field of surgical endeavour has widened, new problems have arisen. Operations are now carried out upon patients so reduced by their disease that formerly interference would not have even have been considered. The outcome of such enterprises depends upon meticulous care in the pre and post-operative treatment, not the least important aspect of which is the maintenance of normal water and electrolyte metabolism. In this connection it is interesting to recall that as long ago as 1831 Dr. W. B. O'Shaughnessy of Newcastle upon Tyne recognised the essentials of water and electrolyte depletion and also outlined treatment. In a brief letter to the London Medical Gazette he summarised the changes which occur in the blood of patients suffering from cholera. He stated that:1. "The blood drawn in the worse cases of cholera is unchanged in its anatomical or globular structure."2. It has lost a large proportion of its water, 1000 parts of cholera serum having but the average of 850 parts of water."3. "It has lost also a great proportion of its neutral saline ingredients."4. "Of the free alkali contained in healthy serum, not a particle is present in some cholera cases, and barely a trace in others."5. "Urea exists in the cases where suppression of urina has been a marked sympton."6. "All the salts deficient in the blood, especially the alkali or carbonate of soda, are present in large quantities in the peculiar white dejected matters."From the early papers and the very numerous investigations which have since been carried out, it has become obvious that loss of water and sodium chloride from the body so alters "the innumerable and interrelated chemical reactions that together accomplish what we call metabolism that life itself may thereby be seriously endangered. Therefore rational fluid therapy must be directed not to restoring the normal body content of any particular component of the body fluids (which indeed is separately impossible), but to the restoration and maintenance of the normal volume, composition, and distribution of the body fluids as a whole, so that metabolism may proceed under the most favourable of circumstances. It is the purpose of this paper to discuss the metabolism of the body fluids, the practical applications of fluid therapy in surgical patients, and to make some contribution to our knowledge of the therapeutics of sodium chloride