Michael Lamperth - Academia.edu (original) (raw)

Papers by Michael Lamperth

Prologue C haucer's characters in The Canterbury Tales meet on their journey to the shrine of Tho... more Prologue C haucer's characters in The Canterbury Tales meet on their journey to the shrine of Thomas à Becket. They are on a pilgrimage, a special kind of journey that brings a diverse group of people together in a common purpose. As they converge on the place of pilgrimage, the tales they tell are informed by the varied experiences of their lives. The stories we tell here are of individuals brought together by a single objective: to find a solution better than total root replacement for people whose lives are threatened by aortic dilatation due to Marfan syndrome. Chaucer's pilgrims meet in the Tabard Inn in Southwark, where their journey to Canterbury is to begin. This modern journey began in St George's Hospital at the 2000 meeting of the Marfan Association, when the surgeon [TT] told his tale, an account of best current practice and its attendant risks.

This paper presents the development of a hybrid thermal model for the EVO Electric AFM 140 Axial ... more This paper presents the development of a hybrid thermal model for the EVO Electric AFM 140 Axial Flux Permanent Magnet (AFPM) machine as used in hybrid and electric vehicles. The adopted approach is based on a hybrid lumped parameter and finite difference method. The proposed method divides each motor component into regular elements which are connected together in a thermal resistance network representing all the physical connections in all three dimensions. The element shape and size are chosen according to the component geometry to ensure consistency. The fluid domain is lumped into one region with averaged heat transfer parameters connecting it to the solid domain. Some model parameters are obtained from Computation Fluid Dynamic (CFD) simulation and empirical data. The hybrid thermal model is described by a set of coupled linear first order differential equations which is discretised and solved iteratively to obtain the temperature profile. The computation involved is low and th...

M. Rea, Z. Tse, H. Elhawary, M. Lamperth, G. Bydder, and I. Young Radiological Sciences Unit, Imp... more M. Rea, Z. Tse, H. Elhawary, M. Lamperth, G. Bydder, and I. Young Radiological Sciences Unit, Imperial College London, London, UK, United Kingdom, Mechanical Engineering, Imperial College London, London, England, United Kingdom, Brigham Womens Hospital, Boston, United States, Radiology, University of California San Diego, San Diego, CA, United States, Electrical Engineering, Imperial College London, London, United Kingdom

The concept of a turbogenerator consisting of a small gas turbine directly coupled to a new high ... more The concept of a turbogenerator consisting of a small gas turbine directly coupled to a new high speed permanent magnet alternator is described. Its application to hybrid electric vehicles is proposed and simulations have been performed and presented for the Federal Urban Driving Cycle. Comparisons have been made between a vehicle with a conventional powertrain and that of the hybrid electric system with a turbogenerator. The significance of achieving low emissions and reduced fuel consumption with a turbogenerator based system is illustrated. (A) For the covering abstract of the conference see IRRD 493111.

Hybrid modules have been adopted by vehicle manufacturers to create hybrid variants of existing m... more Hybrid modules have been adopted by vehicle manufacturers to create hybrid variants of existing models. This paper presents the potential performance of an axial flux permanent magnet machine against typical hybrid module design requirements. A multi physics analytical model is implemented and validated experimentally. This is followed by a parametric design study showing that the axial flux topology provides its maximum specific torques and powers within the available package space. Based on the hybrid module design requirements a design is identified for further development and its performance is confirmed through 3D finite element analysis. It is found that in a package space of 300mm diameter and 90mm length (including casings and water jacket) the axial flux topology offers 390Nm and 98kW for lOs, and 159Nm and 66kW continuously. Future work will include full mechanical design and prototyping of the concept.

EVO Electric has designed, built and tested the DuoDrive hybrid system based on proprietary axial... more EVO Electric has designed, built and tested the DuoDrive hybrid system based on proprietary axial flux motor technology, and installed it in a London Taxi Cab. The DuoDrive switchable series/parallel hybrid system has demonstrated a 60% improvement in fuel economy compared to a conventional taxi when operated over an urban drive cycle. As with many hybrid vehicles, a large part of this improvement is attributed to effective and efficient recapture of braking energy. The amount of braking energy that can be recovered, and the efficiency with which it can be returned to the road will therefore have a significant impact on the overall fuel economy of the vehicle. One factor that limits the amount of energy that can be recovered is the allowable charge rate of the battery, as braking events are usually high power and in a hybrid vehicle the battery size is generally small. The vehicle described in this paper has an energy storage system comprised of high power ultra-capacitors and a hig...

This paper presents the findings of a finite element analysis (FEA) investigation into the effect... more This paper presents the findings of a finite element analysis (FEA) investigation into the effect of rotor/stator misalignment on motor performance in a single rotor, dual stator, axial flux electric motor (AFM). Results obtained from the FEA are in good agreement with experimental measurements giving confidence in the use of the model. The results are useful to machine designers who wish to determine the sensitivity of rotor/stator misalignment, due to assembly errors or tolerance stack on machine performance. Axial offset of the rotor in the air gap is found to cause unbalanced axial forces on the rotor of up to 1400 N. The difference in iron loss between stators increased by 17 and 40% at high speed under open- and short-circuit conditions, respectively. Conversely, angular offset between the two stators was found to have little impact on unbalanced rotor forces and iron loss but a relatively large impact on recirculating currents within the machine which lead to uneven heating o...

Introduction The current gold standard for the confirmation of suspected prostate cancers is a se... more Introduction The current gold standard for the confirmation of suspected prostate cancers is a sextant biopsy guided by transrectal ultrasound (TRUS) [1]. This is in widespread use despite the poor SNR of the modality and the reported low sensitivity [1,2] of the technique due to its lack of targeting ability within the prostate gland. Recent work has shown how MR-guidance can be used for easier targeting leading to improved diagnostic ability and a reduction in repeat procedures [3,4]. Here we report on the clinical use of a MR-compatible electromechanical system for prostate biopsy which employs remote actuation to position and fire the needle, with the patient remaining inside the scanner bore.

Lecture Notes in Computer Science, 2006

The excellent soft tissue contrast of Magnetic Resonance Imaging (MRI) has encouraged the develop... more The excellent soft tissue contrast of Magnetic Resonance Imaging (MRI) has encouraged the development of MRI compatible systems capable of combining the advantages of robotic manipulators with high quality anatomical images. Continuing this development, a new five DOF prostate biopsy manipulator has been designed for use inside a closed 1.5T MRI scanner. Space constraints in the bore and the current trend to restrict field strength exposure for operators indicate that a master-slave configuration is ideal for controlling the robotic system from outside the bore. This system has been designed to work with piezoceramic motors and optical encoders placed inside or near the field of view of the scanner, using real time image guidance for targeting biopsies to specific lesions in the prostate. MRI tests have been performed to prove the feasibility of this concept and a one DOF proof-of-concept test rig implementing closed loop position control has been tested and is presented here. A first prototype of the slave manipulator has been designed and manufactured incorporating this new technology.

The Lancet, 2004

Search by Subject Search using Medical Subject Headings (< b> MeSH</b&gt... more Search by Subject Search using Medical Subject Headings (< b> MeSH</b>), a controlled vocabulary for indexing life sciences content.< br/> Note that some records do not have MeSH. These include Patents and the latest PubMed and PubMed Central records.

Interactive cardiovascular and thoracic surgery, 2010

Fatal aortic dissection commonly occurs in Marfan syndrome. Prevention currently relies on electi... more Fatal aortic dissection commonly occurs in Marfan syndrome. Prevention currently relies on elective replacement of the aortic root. We are evaluating the placement of a manufactured, bespoke external support derived from a computer aided design in a prospective study. In the first ten patients, measurements were made consistently of the ascending aorta at the level of closure of the aortic valve cusps from magnetic resonance imaging (MRI) studies taken preoperatively and at fixed intervals thereafter. Before and after images were presented for measurement amongst duplicate images of 37 unoperated Marfan patients to permit assessment of intra-observer measurement reproducibility. All images were presented in random sequence to a radiologist unaware of the research question. The largest difference between the preoperative measurement and that made at least one year after surgery was determined. All patients had surgery as planned without complications and were alive at one year. In ei...

Lecture Notes in Computer Science

When imaging tendons and cartilage in a MRI scanner, an increase in signal intensity is observed ... more When imaging tendons and cartilage in a MRI scanner, an increase in signal intensity is observed when they are oriented at 55 degrees with respect to Bo (the "magic angle"). There is a clear clinical importance for considering this effect as part of the diagnosis of orthopaedic and other injury. Experimental studies of this phenomenon have been made harder by practical difficulties of tissue positioning and orientation in the confined environment of cylindrical scanners. An MRI compatible mechatronic system has been developed to position a variety of limbs inside the field of view of the scanner, to be used as a diagnostic and research tool. It is actuated with a novel pneumatic motor comprised of a heavily geared down air turbine, and is controlled in a closed loop using standard optical encoders. MR compatibility is demonstrated as well as the results of preliminary trials used to image the Achilles tendon of human volunteers at different orientations. A 4 to 13 fold increase in signal at the tendon is observed at the magic angle.

Proceedings of the ICE - Energy, 2007

There are three main energy options for decarbonising road transport: biofuels, hydrogen and elec... more There are three main energy options for decarbonising road transport: biofuels, hydrogen and electricity. While the ‘hydrogen economy’ and fuel-cell vehicles (FCVs) are often seen as the only viable long-term option, and liquid biofuels as the only short/medium-term option, the potential for battery-dominant electric vehicles (including ‘plug-in’ hybrids) charged by low-carbon electricity has tended to be neglected in recent policy debates. However, even if low-carbon hydrogen were available it is likely to be as efficient to convert it to electricity for battery electric vehicles and plug-in hybrids as to use it for FCVs. Low-carbon electricity (e.g. from renewables, nuclear) is more efficiently used directly in electric vehicles than via conversion to hydrogen. Electric vehicles also generally have less challenging technical, infrastructural, financial and commercial barriers. In particular, the electrification of road transport can ‘piggyback’ on existing grid and off-peak genera...

Magnetic Resonance Materials in Physics, Biology and Medicine, 2008

Objective Electromechanical devices enable increased accuracy in surgical procedures, and the rec... more Objective Electromechanical devices enable increased accuracy in surgical procedures, and the recent development of MRI-compatible mechatronics permits the use of MRI for real-time image guidance. Integrated imaging of resonant micro-coil fiducials provides an accurate method of tracking devices in a scanner with increased flexibility compared to gradient tracking. Here we report on the ability of ten different image-processing algorithms to track micro-coil fiducials with sub-pixel accuracy. Materials and methods Five algorithms: maximum pixel, barycentric weighting, linear interpolation, quadratic fitting and Gaussian fitting were applied both directly to the pixel intensity matrix and to the cross-correlation matrix obtained by 2D convolution with a reference image. Results Using images of a 3 mm fiducial marker and a pixel size of 1.1 mm, intensity linear interpolation, which calculates the position of the fiducial centre by interpolating the pixel data to find the fiducial edges, was found to give the best performance for minimal computing power; a maximum error of 0.22 mm was observed in fiducial localisation for displacements up to 40 mm. The inherent standard deviation of fiducial localisation was 0.04 mm. Conclusion This work enables greater accuracy to be achieved in passive fiducial tracking.

IEEE/ASME Transactions on Mechatronics, 2008

The "magic angle" effect consists of the increase in signal intensity observed at a tendon or car... more The "magic angle" effect consists of the increase in signal intensity observed at a tendon or cartilage in a magnetic resonance image, when the tissue is oriented at an angle of approximately 55 • with respect to the main magnetic field B 0. The exploitation of this phenomenon is often used to assist diagnosis of tendinous and other diseases, although practical difficulties derived from positioning target tissue at the desired orientation inside closed-bore scanners has made this exploitation hard to implement. A 3-DOF MR-compatible mechatronic system has been developed to position a variety of limbs at the magic angle inside a closedbore scanner, actuated by a custom-developed pneumatic air motor. The system is capable of locating the desired anatomy with high accuracy, and is designed to position the target tissue at a minimal distance from the isocenter. The compatibility of the system is demonstrated, producing negligible artifacts and an insignificant reduction in signal to noise of the image. Preliminary clinical trials scanning the Achilles tendon of healthy volunteers prove the functionality of the device. An increase in signal intensity of up to 21-fold has been recorded in the tendon at the magic angle.

Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering, 2009

Most clinical magnetic resonance systems do not have access to ultrashort echo time (UTE) imaging... more Most clinical magnetic resonance systems do not have access to ultrashort echo time (UTE) imaging. The aim of this project was to develop a fully independent imaging insert for clinical MR systems to provide this new research application without disturbing routine operation. The initial clinical target for the system was improved orthopedic upper limb imaging using ultrashort repeat and echo time acquisitions. Echo times as short as TE ¼ 80 ls were attained for standard 2DFT gradient echo sequences and TE ¼ 25 ls for asymmetrically sampled radial acquisitions using the 160 mm inside diameter symmetrical cylindrical insert gradient set. The spectrometer was able to acquire 32 channels simultaneously with 14 bit resolution at up to 2.5 MS/s and had broadband operation from 250 kHz up to 200 MHz. Only eight active RF channels were constructed and used for this study. Acoustic noise with the insert coil was up to 30 dbA quieter than a whole body gradient system operating at the same gradient strength. The insert provides a useful method of performing UTE imaging using a standard clinical MRI system with no disturbance to normal operation.

Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2008

Owing to their highly ordered structure, tendons and cartilage appear with low signal intensity w... more Owing to their highly ordered structure, tendons and cartilage appear with low signal intensity when imaged using magnetic resonance imaging (MRI) scanners. A significant increase in signal can be observed when these structures are oriented at 55u (termed the magic angle) with respect to the static field B 0. There is a clear clinical importance in exploiting this effect as part of the diagnosis of injury. Experimental studies of this phenomenon have been made harder by the practical difficulties associated with tissue positioning and orientation in the confined environment of closed-bore scanners. An MRI-compatible mechatronic system has been developed, which is capable of positioning a number of limbs to a desired orientation inside the scanner, to be used as a diagnostic and research tool. It is actuated with a novel pneumatic motor consisting of a heavily geared-down air turbine, presenting high torques and good accuracy. The system is shown to be magnetic resonance compatible and the results of preliminary trials using the device to image the Achilles tendon of human volunteers at different orientations are presented. An increase of four fold to thirteen fold in signal intensity can be observed at the magic angle.