bluuebunny/crossref_metadata_2025_split huggingface dataset:
Non-destructive and non-invasive observation of friction and wear of human joints and of fracture initiation by acoustic emission
Authors: Schwalbe H-J , Bamfaste G , Franke R-P 
Published: October 2002

Quality control in orthopaedic diagnostics according to DIN EN ISO 9000ff requires methods of non-destructive process control, which do not harm the patient by radiation or by invasive examinations. To obtain an improvement in health economy, quality-controlled and non-destructive measurements have to be introduced into the diagnostics and therapy of human joints and bones. A non-invasive evaluation of the state of wear of human joints and of the cracking tendency of bones is, as of today's point of knowledge, not established. The analysis of acoustic emission signals allows the prediction of bone rupture far below the fracture load. The evaluation of dry and wet bone samples revealed that it is possible to conclude from crack initiation to the bone strength and thus to predict the probability of bone rupture.
On-line computer system to minimize laser injuries during surgery: Preliminary system layout and proposal of the key features
Authors: Canestri Franco 
Published: October 2002

The aim of this paper is to investigate some new user interface ideas and related application packages which aim to improve the degree of safety in an operating room during surgical operations in which an invasive laser beam is deployed. The overall value of the proposition is that a means is provided which ensures the successful completion of the surgical case while minimizing the risk of thermal and mechanical injuries to healthy tissues adjacent to the surgical field. According to surgeons operating with a variety of CO2 lasers available at both the National Cancer Institute in Milan, Italy, and the Sackler School of Medicine, Tel Aviv University, Israel, each laser device presents different cutting and coagulation properties. In order to identify which ‘ideal’ procedure might corroborate the subjective impression of each surgeon and also to provide one common tool to ensure procedures with a high level of safety, the author has worked for several months with surgeons and technicians of both Institutions to define the general design of a new on-line surgical operation planning and design system to be used during the pre-operative briefing activities and also as a consultation tool during operation. This software package will be developed and tested on both ‘C’ and FORTRAN compilers running on a commercially available PC which is driving a continuous wave (CW) CO2 laser device via its Instrument-Bus interface. The present proposal describes the details of a software package called LCA (Laser-beam Controller and Adviser) which performs several controls in parallel on the key output parameters of a laser beam device during its utilization in delicate surgical operations. The required performances of this device needed during a given surgical operation are pre-simulated and compared against the well-known safety limits, which are stored in the computer's mass storage. If the surgeon's decision about the laser device set-up are considered to be too close to the required physiological safety limits, then the SW alerts the surgeon and proposes alternatives based on other combinations of both HW and SW configurations. An additional application of LCA uses this SW as a warning tool during the operation itself. If a wrong set-up of the laser device is accidentally used, an alarm will be generated and the laser beam automatically switched-off prior to an ‘incident report’ printout. The operation will continue only when the surgeon validates the choices that the SW suggests for implementation. If necessary, the surgeon can switch off the device and continue to operate it manually. In this case, the surveillance mode will be totally excluded.
Combustion characteristics of higher-alcohol/gasoline blends
Authors: Gautam M , Martin D. W. 
Published: October 2002

An experimental investigation of combustion characteristics of higher-alcohol/gasoline [unleaded test gas 96 (UTG 96)] blends is presented. Lower alcohols (methanol and ethanol) have been used in the past as fuel extenders by mixing them with gasoline, but relatively little work has been reported on higher alcohols (propanol, butanol and pentanol). All these alcohols can be produced from coal-derived syngas. Given the abundant coal reserves in the United States, use of such higher alcohols offers an attractive alternative to alleviate the country's growing needs for transportation fuels. Comparisons of knock limits, indicated mean effective pressure (i.m.e.p.), emissions and fuel characteristics between higher-alcohol/gasoline blends and neat gasoline were made to determine the advantages and disadvantages of blending alcohol with gasoline. All tests were conducted on a single-cylinder Waukesha cooperative fuel research (CFR) engine operating at steady state conditions and stoichiometric air-fuel ratio. The data show that higher-alcohol/gasoline blends have a greater resistance to knock than neat gasoline does, as indicated by the knock resistance indicator (KRI) and the (RON+MON)/2 antiknock index (where RON is the research octane number and MON the motor octane number). Ignition delay and combustion interval data show that higher-alcohol/gasoline blends tend to have faster flame speeds.
Sulphur removal from flue gases in the utility sector: Practicalities and economics
Authors: Cooper J R , Collins R , Massey T H , Venkateswaran N , Westaway S 
Published: October 2002

Sulphur dioxide control in the utility sector has come of age with established technologies supplied by companies with international reputations and good track records now taking major contracts on a regular basis. Although not employed as extensively as originally anticipated in the United Kingdom, subject to gaining the necessary consents and authorizations, a major contract may be placed for sulphur control on Orimulsion fired plant. World-wide use of desulphurization technologies continues to expand with many installations now under construction or in operation in areas such as the Pacific Rim and Eastern Europe to meet increasingly stringent environmental regulations aimed at controlling unwanted environmental effects. Previous papers from suppliers and operators have tended to concentrate on the theory of the process or the practical engineering aspects of on-site installation and operation. This paper considers the overall impact and cost of various systems and reviews established and developing systems of flue gas desulphurization processes. It focuses not only on the technology but also on the supply of raw materials, marketing and/or disposal of products, the economics of such systems and some of their potential environmental impacts both on and off site. In this respect the paper reviews all the major areas to be considered in the selection of a process for a particular site.
Emission behaviour of a catalytic burner fuelled with mixtures of hydrogen and methanol
Authors: Wiese W , Bröckerhoff P , Emonts B , Riedel E 
Published: October 2002

A catalytic radiant burner was chosen as the process heat source in a fuel cell drive system. The advantage of a catalytic burner is the low level of harmful substances in the flue gas. Besides the production of process heat, another task of the burner is to convert different gas mixtures effectively from the system into CO2 and H2O. The basic burner structure is a ceramic cylinder to which the fuel gas, pre-mixed with air, is internally supplied. On the outer surface of the cylinder, a wire mesh coated with noble metal is provided on which the combustion takes place catalytically. The emission behaviour of the burner was investigated under different operation conditions concerning the gas mixture and the catalyst. From the results, the mechanisms of the formation of pollutants are discussed and the suitability of the burner concept is checked by comparing the measured emissions with the emission standards. The operation condition ranges are determined under which the burner works in the drive system without exceeding the emission standards.
Modelling and validation of a fast switching valve intended for combustion engine valve trains
Authors: Pohl J , Sethson M , Krus P , Palmberg J-O 
Published: October 2002

In recent years much research has been done in the area of variable-valve actuation in order to improve the efficiency of combustion engines. Currently, a number of different concepts for variable-valve actuation are under development or at a prototype stage. Hydraulic actuation has been an obvious candidate, but the lack of sufficiently fast switching valves with appropriate flowrates has been the major shortcoming. Design of such highly dynamic systems requires accurate models of the actual included components. In this paper a model of a fast 2/2 switching valve is presented, where both the magnetic path as well as the spool assembly are modelled. The model presented here is primarily aimed at system simulations; therefore it has to be kept simple with the number of parameters low. Some of the parameters are often hard to obtain, especially when it comes to magnetic material properties. In this study, an optimization strategy has been utilized in order to parameterize the model against measured data. However, even for major deviations from the operational point used for the model adaptation, the model predicts the valve response sufficiently accurately.
Output prediction in systems with backlash
Authors: Schenker B , Agarwal M 
Published: October 2002

Systems exhibiting backlash pose a challenging prediction problem, since they involve state multiplicity for finite-order input-output models. Future outputs, given future inputs, cannot adequately be predicted using only a few past outputs and inputs, but are critically dependent on the internal state of these systems. In case the presence of steady state multiplicity is not known, a reliable predictor should be able to handle it without this explicit knowledge; in case the presence is known, the predictor would do well to be able to benefit from this knowledge even when the rest of the process might not be known. Conventional empirical models such as feedforward neural networks cannot accurately represent systems that entail state multiplicity for their intrinsically limited input—output system representation. This work employs a state-feedback neural network structure, previously proposed by the authors, as an attractive solution to the problem of reliable output prediction for systems with hysteresis or backlash. By generating a state-space mapping of the system, the proposed network structure is able to store the relevant information in the state, thereby avoiding the information loss incurred by the input-output predictor. The feedback structure also yields more accurate multistep predictions. The presented results for a simulation example of a backlash system demonstrate the superiority of the feedback structure over the feedforward network for achieving satisfactory prediction accuracy without explicit knowledge of the presence of backlash.
Robot torque and position control using an electrorheological actuator
Authors: Brookfield D J , Dlodlo Z B 
Published: October 2002

An electrorheological (ER) clutch driven from a constant speed motor provides a steady torque independent of shaft angle and can be controlled by control of the applied field. Such an actuator avoids the ‘cogging’ variation in torque observed in d.c. servo-motors and is thus well suited to robot control applications, particularly in view of the very rapid time response of ER clutches (≍ 10−3s). However, the relationship between applied field and torque is difficult to model, being both non-linear and time varying. Whereas the non-linearity can be shown to be relatively small, the time-varying characteristic has remained a problem.In most controlled plants, a non-linear or time-varying characteristic can be mitigated by providing a closed control loop around the plant. A PID (proportional plus integral plus derivative)-based torque controller was developed and tested. This was shown to be stable with at least critical damping and to exhibit low steady state error. Design of the controller was facilitated by the identification of the open-loop transfer function of the ER actuator.The ER actuator with torque feedback was used to position a small robot link. A second PID control loop responding to the error in the link position and tuned using the standard Ziegler and Nichols method was designed and tested. A steady state error of less than 0.75 mm was achieved with a 2 per cent settling time of 2.0 s. Finally, the link position was controlled using a single-loop controller with no torque feedback and a similar steady state error achieved with a 2 per cent settling time of 1.4 s. It is argued that the ER torque actuator is ideally suited to the actuation of robot joints where precise smooth movement is required.
Theoretical analysis of pressure and flow ripple in flexible hoses containing tuners
Authors: Drew J E , Longmore D K , Johnston D N 
Published: October 2002

In automotive power steering systems it is common practice to include highly expandible hoses containing tubular inserts, referred to as tuners, to minimize the pump-generated pressure ripple. A theoretical model of a flexible hose containing a tuner is described, which can be used to compute the fluid-borne noise characteristics of complete systems.Excellent agreement with experimental measurements is obtained. Leakage through the tuner wall is shown to have a strong effect on the results. With the common type of spiral wound tuner, most of the damping present is obtained from this leakage and from energy loss in the hose wall, and for low-viscosity fluids it may be acceptable to ignore the effect of fluid viscosity.
A fractal analysis of adhesive friction between rough solids in gentle sliding
Authors: Sahoo P , Roy Chowdhury S. K. 
Published: October 2002

Studies of adhesive friction have always relied on careful experiments, and many plausible theories based on the observations now exist to describe the fundamental causes of interfacial bonding between rough solids. In this regard, an analytical model based on surface forces that operate within short ranges is probably not out of place. The analysis of friction is closely associated with that of adhesion between rough solids. Such analyses of adhesion and friction using a random rough surface model have already been described elsewhere. Adhesive bonds may occur at the peaks of nanometric size asperities even though the microscopic roughness would inhibit the surfaces from approaching close separation. It is therefore necessary to account for the effect of asperities ranging from nanometre to micrometre level for a true representation of asperity interactions at the interface and this essentially requires a scale-independent model such as a fractal approach. The paper describes friction between rough solids using a fractal model and the results are compared with those using a conventional approach. The results explain some of the earlier experimental observations. It also seems that the variation in the fractal dimension D may produce a broad spectrum of results which may explain phenomenologically some of the experimental observations, hitherto not explained.
Dynamic behaviours of piston rings and their practical impact. Part 2: Oil transport, friction and wear of ring/liner interface and the effects of piston and ring dynamics
Authors: Tian T 
Published: October 2002

The paper discusses several important processes that have great impact on the lubrication between the top two rings and the liner. The analysis is conducted on the basis of the calculation results on a heavy-duty (HD) diesel engine using theoretical models. Oil supply mechanisms to different liner regions are analysed, and emphasis is given to the oil transport to the top liner region that is found critical to friction, wear and oil consumption in HD diesel engines. Additionally, the paper discusses the oil supply to the second ring, its uncertainties and the effect on the prediction of the performance of the top two rings. Furthermore, the effects of dynamics of the piston and rings on friction, wear and oil transport are illustrated and the effects of bore distortion on oil transport are discussed. For practical purposes, a formula to describe the second ring running surface profile is given based on simple geometrical constraint. A new truncation method is rendered for plateau surface roughness in order to effectively use the existing mixed lubrication models.
Artificial neural networks for modelling dynamics of impacting bodies and vehicles
Authors: Omar T A , Eskandarian A , Bedewi N E 
Published: October 2002

A new approach is demonstrated and tested for modelling the non-linear multi-body dynamics problem of two impacting bodies. An advanced recurrent artificial neural network (ANN) is used to model this highly non-linear dynamic problem. The equations of motion of the dynamic system are used to explain the required inputs for the ANN. The developed networks are trained to predict the acceleration profiles of the impacting objects. Each object is represented by a corresponding ANN. The mutual effect between the two objects, during the impact, is also considered by training the two ANNs simultaneously. Two numerical examples are used to demonstrate the ability of the new developed approach. The first is the dynamic impact problem of two non-linear lumped systems. The second is two different vehicles in frontal impacts. For each case, the problem is numerically solved for several impact scenarios and the results are used to prepare the data required for training and testing the developed ANNs. The results of the two numerical examples demonstrated the ability of the ANNs to store the non-linear dynamic characteristics of the impacting objects after a successful supervised training. The trained networks are capable of modelling non-linear multi-body dynamics and impact problems.
The modelling and simulation of vehicle handling Part 2: Vehicle modelling
Authors: Blundell M V 
Published: October 2002

This is the second in a series of four papers looking at the application of computer-based analysis methods to model vehicles and simulate vehicle handling. The material contained in these papers is based on a study carried out in order to investigate the influence of suspension and tyre modelling on the outputs predicted by vehicle handling simulations. The papers deal with analysis methods, vehicle modelling, tyre modelling and handling simulation. In this paper the methods used to model the vehicle systems relevant to handling simulations using a multi-body systems analysis computer program are described, with the emphasis placed mainly on the modelling of suspension systems. A range of full vehicle models, which use simplified representations of the suspension system, are also described as these models form the basis of a set of comparisons described in Part 4 of this series. Modelling of other vehicle systems such as the steering system and roll bars is also discussed. Tyre modelling is a large topic and as such is covered separately in Part 3 of this series of papers. All of the examples used to illustrate the concepts explained throughout this series of papers have been generated using the ADAMS (Automatic Dynamic Analysis of Mechanical Systems) program.
Experimental and numerical analyses of the combustion process in a direct injection gasoline engine
Authors: Reissing J , Peters H , Kech J. M. , Spicher U 
Published: October 2002

Gasoline direct injection (GDI) spark ignition engine technology is advancing at a rapid rate. The development and optimization of GDI engines requires new experimental methods and numerical models to analyse the in-cylinder processes. Therefore the objective of this paper is to present numerical and experimental methods to analyse the combustion process in GDI engines. The numerical investigation of a four-stroke three-valve GDI engine was performed with the code KIVA-3V [1]. For the calculation of the turbulent combustion a model for partially premixed combustion, developed and implemented by Kech [4], was used. The results of the numerical investigation are compared to experimental results, obtained using an optical fibre technique in combination with spectroscopic temperature measurements under different engine conditions. This comparison shows good agreement in temporal progression of pressure. Both the numerical simulation and the experimental investigation predicted comparable combustion phenomena.
A methodology for engine design using multi-dimensional modelling and genetic algorithms with validation through experiments
Authors: Senecal P. K. , Montgomery D. T. , Reitz R. D. 
Published: October 2002

A methodology for internal combustion engine design has been formulated which incorporates multidimensional modelling and experiments to optimize and simulate direct injection diesel engine combustion and emissions formation. The computer code KIVA-GA performs full-cycle engine simulations within the framework of a genetic algorithm (GA) global optimization code. The methodology is applied to optimize a heavy-duty diesel truck engine. The study simultaneously investigated the effects of six engine input parameters on emissions and performance for a high-speed medium-load operating point. The start of injection (SOI), injection pressure, amount of exhaust gas recirculation (EGR), boost pressure and split injection rate shape were optimized. The convergence of the GA optimization process is demonstrated and the results were compared to those of the experimental optimization study employing a response surface method (RSM), which uses statistically designed experiments to determine an optimum design. In addition, the parameters of the computationally predicted optimum were run experimentally and good agreement was obtained. The potential for ultra-low emissions levels was assessed through additional computational GA runs that included higher maximum EGR levels (up to 50 per cent). The predicted optimum results in significantly lower soot and NOx emissions together with improved fuel consumption compared to the baseline design. The present results indicate that an efficient design methodology has been developed for optimization of internal combustion engines, one that allows simultaneous optimization of a large number of parameters.
Comparison of in-cylinder coherent anti-Stokes-Raman scattering temperature measurements with predictions from an engine simulation
Authors: Ewart P , Williams R. B. , Lim E. P. , Stone C. R. 
Published: October 2002

The objective of this work was to compare the burned gas temperature measured using coherent anti-Stokes-Raman scattering (CARS) with the predictions of a multiple-zone computer simulation of combustion. The tests were at various engine operating conditions with different fuels. Mean cycle modelling was used initially to obtain the appropriate heat transfer tuning parameters for the engine simulation by matching to the cylinder pressure. The predicted mean cycle burned gas temperatures gave good agreement with the measured mean temperatures. Similarly, cycle-by-cycle modelling produced burned gas temperatures that agree with the measured values. This work showed that the multi-zone computer simulation could accurately predict the burned gas temperature once the fuel burn rate and completeness of combustion have been analysed and the model tuned correctly. The effects of methanol, methane, toluene and iso-octane on the burned gas temperature were investigated. It was found that the fuel burn rate and the adiabatic flame temperature affected the burned gas temperature. Fuels with a high burn rate (such as methanol) have a lower burned gas temperature towards the end of the engine cycle. Toluene has the highest adiabatic flame temperature and hence gave the highest burned gas temperature.