Magnetic drive system for a new centrifugal rotary blood pump

The purpose of this investigation was to design a novel magnetic drive and bearing system for a new centrifugal rotary blood pump (CRBP). The drive system consists of two components: (i) permanent magnets within the impeller of the CRBP; and (ii) the driving electromagnets. Orientation of the magnets varies from axial through to 60° included out-lean (conical configuration). Permanent magnets replace the electromagnet drive to allow easier characterization. The performance characteristics tested were the axial force of attraction between the stator and rotor at angles of rotational alignment, Ø, and the corresponding torque at those angles. The drive components were tested for various magnetic cone angles, ?. The test was repeated for three backing conditions: (i) non-backed; (ii) steel-cupped; and (iii) steel plate back-iron, performed on an Instron tensile testing machine. Experimental results were expanded upon through finite element and boundary element analysis (BEM). The force/torque characteristics were maximal for a 12-magnet configuration at 0° cone angle with steel-back iron (axial force = 60 N, torque = 0.375 Nm). BEM showed how introducing a cone angle increases the radial restoring force threefold while not compromising axial bearing force. Magnets in the drive system may be orientated not only to provide adequate coupling to drive the CRBP, but to provide significant axial and radial bearing forces capable of withstanding over 100 m/s2 shock excitation on the impeller. Although the 12 magnet 0° (?) configuration yielded the greatest force/torque characteristic, this was seen as potentially unattractive as this magnetic cone angle yielded poor radial restoring force characteristics.

Dynamic behaviour of rotary mechanical seals

This thesis covers both experimental and computer investigations into the dynamic behaviour of mechanical seals. The literature survey shows no investigations on the effect of vibration on mechanical seals of the type common in the various process industries. Typical seal designs are discussed. A form of Reynolds' equation has been developed that permits the calculation of stiffnesses and damping coefficients for the fluid film. The dynamics of the mechanical seal floating ring have been investigated using approximate formulae, and it has been shown that the floating ring will behave as a rigid body. Some elements, such as the radial damping due to the fluid film, are small and may be neglected. The equations of motion of the floating ring have been developed utilising the significant elements, and a solution technique described. The stiffness and damping coefficients of nitrile rubber o-rings have been obtained. These show a wide variation, with a constant stiffness up to 60 Hz. The importance of the effect of temperature on the properties is discussed. An unsuccessful test rig is described in the appendices. The dynamic behaviour of a mechanical seal has been investigated experimentally, including the effect of changes of speed, sealed pressure and seal geometry. The results, as expected, show that high vibration levels result in both high leakage and seal temperatures. Computer programs have been developed to solve Reynolds' Equation and the equations of motion. Two solution techniques for this latter program were developed, the unsuccesful technique is described in the appendices. Some stability problems were encountered, but despite these the solution shows good agreement with some of the experimental conditions. Possible reasons for the discrepancies are discussed. Various suggestions for future work in this field are given. These include the combining of the programs and more extensive experimental and computer modelling.

Investigation of noise and vibration within an oil flooded sliding vane rotary air compressor

DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT

The characterisation and emulation of rotary mechanical machines

DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT

Study of the uncertainty of angle measurement for a rotary-laser automatic theodolite (R-LAT)

This paper shows how the angular uncertainties can be determined for a rotary-laser automatic theodolite of the type used in (indoor-GPS) iGPS networks. Initially, the fundamental physics of the rotating head device is used to propagate uncertainties using Monte Carlo simulation. This theoretical element of the study shows how the angular uncertainty is affected by internal parameters, the actual values of which are estimated. Experiments are then carried out to determine the actual uncertainty in the azimuth angle. Results are presented that show that uncertainty decreases with sampling duration. Other significant findings are that uncertainty is relatively constant throughout the working volume and that the uncertainty value is not dependent on the size of the reference angle. © 2009 IMechE.

Detection of self-complementary inverted repeats by single forward primer driven PCR

Inverted repeat gene structures designed for silencing functional genes have been widely used both in academic and applied research. The correct orientations of such structures are usually validated with restriction analysis and/or sequencing. We speculated that the inverted repeat nature of such constructs can be shown by a simple PCR reaction with a single forward primer. To test this hypothesis five different constructs were established from grapevine sequences in a hairpin-intron style silencing system. We were able to amplify the appropriate products in each case. Thus a forward-primed PCR alone may be sufficient to prove the inverted repeat nature of the desired constructs.

Dynamics of the Disk-Pendulum Coupled System With Vertical Excitation

This paper investigates the static and dynamic characteristics of the semi-elliptical rocking disk on which a pendulum pinned. This coupled system’s response is also analyzed analytically and numerically when a vertical harmonic excitation is applied to the bottom of the rocking disk. Lagrange’s Equation is used to derive the motion equations of the disk-pendulum coupled system. The second derivative test for the system’s potential energy shows how the location of the pendulum’s pivotal point affects the number and stability of equilibria, and the change of location presents different bifurcation diagrams for different geometries of the rocking disk. For both vertically excited and unforced cases, the coupled system shows chaos easily, but the proper chosen parameters can still help the system reach and keep the steady state. For the steady state of the vertically excited rocking disk without a pendulum, the variation of the excitation’s amplitude and frequency result in the hysteresis for the amplitude of the response. When a pendulum is pinned on the rocking disk, three major categories of steady states are presently in the numerical way.

Rotary moulding of ceramic hollow wares

A novel processing method for the fast and economic production of hollow ceramic components has been developed by combining in situ coagulation moulding with a modified version of the technique of rotary moulding[Binner, J. G. P., Al-Dawery, I. A., Tari, G. and Yan, Y., Rotary casting technique. UK Patent application No. 0506349.0, March 2005], the latter being adapted from the polymer industry. The process was found to require a high solids content suspension, hence development work was performed in this direction though in the end a new, commercial suspension was utilised. Of the three forming routes of gel casting, direct coagulation casting and in situ coagulation moulding, the latter was found to be the most promising for the new process of rotary moulding of ceramics. Due to the low value of clay-based ceramics, a new low cost coagulant was identified and the effect of lactone concentration and temperature on setting time determined. Following substantial optimisation work, it was found that a two-speed approach to multi-axial rotation was the most successful; medium sized cream jugs could be produced in just 7 min. With respect to mould materials, the porous resin normally used for pressure casting of sanitary ware was found to be the best option, though since this is quite expensive conventional plaster-of-paris moulds were found to be a suitable material to enable companies, particularly SMEs, to become familiar with the technology whilst avoiding high costs for trials. The processed articles could be successfully fired and glazed using gas-fired kilns with no sign of any black cores. Major advantages of the process include the ability to precisely calculate the amount of ceramic slip required, eliminating either slip wastage or the need to pour used slip back into the virgin material as currently happens with slip casting. In addition, since the precursor suspension has a very high solids content, the time and energy required to dry the green product and associated moulds has been considerably reduced. © 2008 Elsevier Ltd. All rights reserved.

Sialadenoma Papilliferum with Inverted Pattern in a Young Patient: A Case Report

BACKGROUND: Sialadenoma papilliferum (SP) is a rare, benign neoplasm of salivary gland origin which manifests as an exophytic papillary excrescence of the mucosa. Indeed, SP is both an exophytic proliferation of papillary stratified squamous epithelium above the mucosal surface and an endophytic salivary ductal proliferation beneath the mucosa. It arises predominantly in minor salivary glands and usually affects patients in the age range of 32-87 years, with reports in young patients being exceedingly rare.

Inverted decoupling internal model control for square stable multivariable time delay systems

This paper presents a new tuning methodology of the main controller of an internal model control structure for n×n stable multivariable processes with multiple time delays based on the centralized inverted decoupling structure. Independently of the system size, very simple general expressions for the controller elements are obtained. The realizability conditions are provided and the specification of the closed-loop requirements is explained. A diagonal filter is added to the proposed control structure in order to improve the disturbance rejection without modifying the nominal set-point response. The effectiveness of the method is illustrated through different simulation examples in comparison with other works.

Governed by the cycle : direct and inverted interest-rate sensitivity of emerging market corporate debt

An innovative approach to quantify interest rate sensitivities of emerging market corporates is proposed. Our focus is centered at price sensitivity of modeled investment grade and high yield portfolios to changes in the present value of modeled portfolios composed of safe-haven assets, which define risk-free interest rates. Our methodology is based on blended yield indexes. Modeled investment horizons are always kept above one year thus allowing to derive empirical implications for practical strategies of interest rate risk management in the banking book. As our study spans over the period 2002 – 2015, it covers interest rate sensitivity of assets under the pre-crisis, crisis, and post-crisis phases of the economic cycles. We demonstrate that the emerging market corporate bonds both, investment grade and high yield types, depending on the phase of a business cycle exhibit diverse regimes of sensitivity to interest rate changes. We observe switching from a direct positive sensitivity under the normal pre-crisis market conditions to an inverted negative sensitivity during distressed turmoil of the recent financial crisis, and than back to direct positive but weaker sensitivity under new normal post-crisis conjuncture. Our unusual blended yield-based approach allows us to present theoretical explanations of such phenomena from economics point of view and helps us to solve an old controversy regarding positive or negative responses of credit spreads to interest rates. We present numerical quantification of sensitivities, which corroborate with our conclusion that hedging of interest rate risk ought to be a dynamic process linked to the phases of business cycles as we evidence a binary-like behavior of interest rate sensitivities along the economic time. Our findings allow banks and financial institutions for approaching downside risk management and optimizing economic capital under Basel III regulatory capital rules.

Modern Ensemble Inverted Space January 29, 2015

Concert Program