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Transmission efficiency and refinement of planetary wheel hub gearing system are key design attributes for heavy and off-highway vehicles. Reduction of power loss, directly leading to the development of new generation ECO-axles requires analysis of gear contacting conditions for lubricated conjunctions to determine frictional performance. This is also affected by gear dynamics, which is a prerequisite for assessment of noise, vibration and harshness performance. Therefore, a combined tribo-dynamic analysis is essential. There is a dearth of such holistic analysis, particularly for the case of wheel hub planetary systems. The paper presents such an analysis, which has not hitherto been reported in literature. The inexorable interplay of transmission efficiency and noise, vibration and harshness refinement is demonstrated. The key attributes of noise, vibration and harshness refinement and transmission efficiency can pose contrary requirements and near-optimal conditions can be highlighted by mesh phasing of gearing contacts, thus alleviating the need for more complex gear teeth modifications entailing prohibitive manufacturing costs.

It is necessary to develop an analytical solution in order to combine predictions with measured tribological parameters and fundamentally understand the mechanism of lubrication in a typical region of engine cycle, using tribometric studies. This paper deals with the development of such a representative approach. An analytical, rather than a numerical approach is expounded, as it is shown to suffice for the purpose of precise time-efficient predictions, which conform well to the measurements. The effect of surface topography, material and operating conditions are ascertained for the representative case of top compression ring—cylinder liner contact at the top dead centre reversal in transition from the compression to power stroke. Stainless steel uncoated surface used as press fit cylinder liners for niche original equipment manufacturer applications are compared with those furnished with a Nickel-Silicon Carbide wear-resistant coating of choice in high performance motorsport.

Friction constitutes nearly one fifth of all engine losses. The main contributory source of frictional losses in most engines is the piston–cylinder system, accounting for nearly half of all the parasitic losses. Minimisation of this is essential for improved fuel efficiency and reduced emissions, which are the main driving forces in engine development. The tribology of piston–cylinder conjunctions is, however, transient in nature. This means that various palliative actions need to be undertaken to suit certain instances during the engine cycle. In general, formation of a coherent film of lubricant of suitable viscosity reduces the chance of boundary interactions for most of the piston cycle. Plateau honing of the cylinder bore surface reduces the ‘peakiness’ of the surface topography. Furthermore, if regularly spaced grooves are provided on the contacting surface, these grooves can act as reservoirs of lubricant. However, at low sliding speeds, which are typically found during piston motion reversals, lubricant entrainment into the contact either ceases or is significantly reduced. Therefore, at the end of the piston strokes, there is a greater chance of boundary interactions, resulting in increased friction. There is a need to engineer the surface topography in these low-relative-speed regions in a manner conducive to the retention of a lubricant film. Surface texturing by means of laser processing or mechanical indentation at the dead centres are used to produce local reservoirs of lubricant as well as to encourage and direct the flow of lubricant into the contact conjunction. The paper shows that such surface-modifying features improve the engine’s output power by as much as 4% over that of the standard cylinder bore surface. To reduce wear and scuffing, particularly at the top dead centre, hard coatings can also be used. However, smooth surfaces and the generally oleophobic nature of hard coatings can increase the chance of adhesion, particularly at low sliding speeds. This means that prevention of wear does not necessarily lead to improved fuel efficiency. Furthermore, it is necessary to determine the geometry of the textured patterns in order to avoid the leakage of oil from the ring-pack conjunctions, which can result in increased emissions as well as lubricant degradation and depletion.

Vehicles sold in the United States and Europe are equipped with a specific set of legal diagnostics, called on-board diagnostics; these are used to monitor the performance of various elements of the emission control system. The driver is informed of any failures by the use of a Check Engine Light on the dashboard of the vehicle and then should return the vehicle to the dealership for rectification. The vehicle manufacturer’s aim is to ensure that the Check Engine Light is only illuminated for legitimate failures. For the calibration of an on-board diagnostics, there needs to be sufficient separation between the response of a good sensor and a failed sensor; the setting of this threshold should be based upon a statistical model of the data so that the predicted failures rate can then be determined. An additional benefit of obtaining a statistical model is that it allows confidence limits to be applied to the data; this then gives the engineer the ability to determine the trade-off between the number of data points and the confidence in the estimated statistical model.

For PAM4 transmission in 400 Gb/s Datacom networks, use of equalization and FEC, and a need to reduce cost, force a replacement of historic eye-mask and TDP tests. We describe that replacement: TDECQ.

This article presents a minimal parameter vehicle simulation model to predict the vertical suspension loads expected during abusive driving manoeuvres, such as a kerb strike event. Impulsive suspension loads are applied to tyre and suspension elements under such conditions. In particular, the aim is to specifically study the reactions of jounce bumper–rebound stop and tyre characteristics. For this purpose, a vehicle in-plane pitch dynamics model with 7 degrees of freedom suffices. Non-linear and hysteretic characteristics of the bump-stop elements are included through a new parametric map concept, based on displacement and velocity-dependent hysteresis. Furthermore, a static tyre model is described, tailored to predict the radial stiffness against penetration of an edge with a flat-type rigid body geometry. The tyre model is derived on the basis of classical membrane theory and represented in terms of only a few input parameters. Model validation is supported through experiments at both component and system levels.

This article provides solution for isothermal mixed hydrodynamic conjunction of the compression ring to cylinder liner. This is obtained using the average flow model representation of Reynolds equation based on pressure- and shear-induced flow factors. In particular, the effects of compression ring axial profile along its face-width and surface topography of contiguous solids are investigated. It is shown that ring geometry may be optimized to improve lubrication, whilst care should be taken in order to avoid oil loss or degradation resulting from any loss of sealing. In predicting friction, it is shown that appropriate surface parameters should be used in-line with the state of wear of the ring. For a new ring against a plateau honed liner, boundary friction contribution during the initial running-in wear phase should be predicted according to the average asperity peak heights protruding above the plateau, whilst the plateau height also takes into account the valleys within the surface roughness or grooves created by any cross-hatch honing would be the appropriate measure of topography for worn rings. The main contributions of the article are in providing an analytic solution as well investigation of ring face-width geometry and effect of wear upon friction. However, it is acknowledged that generated heat, inlet boundary starvation and circumferential non-conformity of ring to the bore surface would affect the film thickness and exacerbate generated friction accordingly. These further considerations would require a numerical solution, rather than an analytical one presented here.

Molybdenum is a refractory metal that is typically used for high-temperature applications due to its high melting point (2615 °C), high-temperature strength, low thermal-expansion coefficient, and high thermal conductivity. The alloying of rare earth elements to molybdenum can help improve oxidation resistance as well as strengthening the alloy via dispersion strengthening due to formation of rare earth oxides. In this study, two binary systems, Mo-Ce and Mo-Y, were thermodynamically assessed based on limited phase equilibria information available in the literature. Self-consistent thermodynamic descriptions for both systems were obtained using the CALPHAD method.

In this article, a profile-fitting methodology was developed to measure the partition coefficients of solute elements during the solidification of Ni-base alloys. Better agreement with the theoretically calculated values is expected if the accuracy of the composition and the homogeneity of the model alloys are enhanced. Regular differential thermal analysis (DTA) measurements were consistently higher than the theoretical transition temperatures, and the differences were smaller when compared to the predictions performed with the thermodynamical database developed by Du et al. The better agreement between the experimental results and the theoretical predictions made with the newly developed database suggests that improvements in the accuracy of the theoretical predictions can still be obtained and are necessary for accurate freckling prediction. Quenching modified DTA (MDTA) experiments were proven to be appropriate for directly measuring the average partition coefficients of the solute elements. Regarding the cooling rate of the first stage of the quenching experiments, it was assumed successfully that the cooling rate prior to the quenching step of 0.083 Ks−1 was sufficiently slow to permit easy quenching, while being fast enough for the primary solidification reaction to depart from the equilibrium model and being closer to the Scheil model of segregation. The minimization of the error function defined from the Scheil equation was found to be an appropriate method for describing the segregation profiles of the quenched samples and permitted good estimations of the partition coefficients of the solute elements. The reliability of the methodology was found to be satisfactory given that the magnitudes calculated for the partition coefficients of the solutes in the multicomponent alloy 718 were found to be very close to the values reported in the literature.

Addition of light rare earth elements in small amounts to refractory metal based alloys (e.g., Cr) can increase both ductility and creep resistance of an alloy because the additives absorb residual oxygen in the alloy by forming oxides that can serve as dispersion strengtheners. In this work, three binary systems, Cr-Ce, Cr-La and Cr-Y, were thermodynamically assessed based on limited experimental data available in the literature using the CALPHAD method. Self-consistent and reasonable thermodynamic descriptions for all three systems were obtained. More importantly, two predictions are made: a peritectic reaction in the La-rich side of Cr-La system and a catatectic reaction in the Y-rich side of Cr-Y system. These predictions and the developed databases are subject to future experiments that are needed to clarify several discrepancies in these binaries.

Transient tyre characteristics can have significant influence in vehicle handling, particularly in anti-lock braking system (ABS), which involves wheel speed oscillations as a result of rapid changes in wheel brake pressure. Hitherto, ABS studies have been conducted mostly with straight-line motion. Relatively simple vehicle models have been used which cannot capture the interactions between non-linear handling dynamics and tyre behaviour. This article takes such interactions into account, using a non-linear 14-degrees-of-freedom vehicle model in combination with three different single-point contact tyre models with transient characteristics. They include a stretched-string-based model, a modified stretched-string model, and a contact mass model. The particularly demanding situation of combined cornering/ABS braking is investigated. It is shown that although all tyre models are of similar bandwidth (maximum frequency ≈ 15 Hz), the simple string tyre model fails to cope with the non-linearities involved in combined braking/cornering and predicts greater braking distances than the two more enhanced tyre models.

In internal combustion engines it is important to manage the wear in the valve and valve seat contact in order to minimise emissions and maximise economy. Traditionally wear in this contact has been controlled by the use of a valve seat insert and the careful selection of materials for both the valve and the insert. More recently, due to the increasing demands for both performance and cost, alternative methods of controlling the wear, and the resulting valve recession, have been sought. Using the heating effect of a laser to induce localised phase transformations, to increase hardness and wear resistance, in materials has been used since the 1970s, however it is only in recent years that it has been able to compete with more established surface treatment techniques, particularly in terms of cost, as new laser hardware has been developed. In this work, a laser has been used to treat the valve seat area of a cast iron cylinder head. In order to optimise the laser parameters for use on the head, preliminary tests were carried out to investigate the fundamental wear characteristics of untreated cast iron and also cast iron with a range of laser treatments. Previous work has identified the predominant wear mechanism in the valve and valve seat contact as impact on valve closure. Two bespoke test machines, one for testing basic specimens and one for testing components, were used to identify the laser parameters most likely to yield acceptable results when applied to a cylinder head to be used in a fired dynamometer test.

The short-term-Fourier-transform (STFT) is used to identify different sources of IC engine-block vibration from single-point acceleration measurements taken with a commercial knock sensor. Interest is focused on using the STFT to distinguish normal combustion from other sources of excitation including valve impact, injector pulses, and abnormal combustion, such as knocking. Positive identification of these other events using a single method can be useful for pre-processing of measured knock-sensor data for neural-network-based reconstruction of cylinder pressure. It can also be useful separately as part of a fast knock detection system. A series of experiments is discussed to create the data to isolate these different events on a 3-cylinder gasoline engine. In each case, the measured data is processed using the STFT to attempt to isolate the occurrence of particular events in the time domain. Four classes of experiments are undertaken: (i) an un-fired (motored) engine, driven by a dynamometer, with spark plugs fitted, and then removed, to isolate valve impact; (ii) a fired engine running under idle conditions, to contrast no-load combustion with no combustion; (iii) a part-loaded engine running normally, and then running with one injector switched-off, and (iv) a fully-loaded engine running normally, and then running with knock-control switched-off. The paper shows that a single Time-frequency analysis method, applied to knock sensor data in the form of an appropriately-tuned STFT, can effectively identify the occurrence of these events in the time domain if responses are adequately separated and strong enough.

The paper will discuss progress towards a new characterisation of architecture based on the activities of the recently formed INCOSE UK Chapter Architecture Working Group. The focus of the paper will be on describing the diversity of opinion we have observed in discussions of the fundamental characteristics of architecture and progress towards resolving the various conflicts that arise. We have made progress in refining the definition of architecture, the understanding of the role of patterns within architecting and how the conceptual underpinnings of architecture may be made consistent with the uses and types of architecture.

A NARX neural network is adapted for cylinder pressure trace reconstruction on a multicylinder engine. Following a systematic study to establish the required NARX input information (using measured pressure traces and simulated crank kinematics), two fully recurrent training algorithms are developed and applied to real engine data. These include a back-propagation-through-time algorithm (BPTT) and an extended Kalman filter (EKF). For multi-cylinder engines, two cases are examined, both assuming crank kinematics is obtained from a single shaft-encoder fitted at the forward end of the crankshaft. In one case, a NARX model is constructed to provide an inverse relationship between the kinematics at the encoder location and the pressure trace in an arbitrary cylinder. In the second case, by transforming the kinematics (to emulate a local encoder), a different NARX model is constructed to relate the kinematics at the crank location of a particular cylinder to the corresponding pressure trace. The accuracy and efficiency of both NARX models is examined for application to a three-cylinder in-line DISI engine (in which pressure traces are measured on all cylinders). The paper shows that the computational requirements of training are substantial and, although the efficiency of the EKF algorithm is better than the BPTT, the fitting accuracies are similarly good. For generalization, however (to unseen data), neither method is yet sufficiently accurate (even for steady state engine operation) unless substantially more training data are used to achieve the target accuracy of ± 4 per cent. The overall conclusion of the paper is that the NARX model has the correct architecture for multicylinder pressure reconstruction.

This paper investigates vehicle dynamic response for the increasingly common manoeuvre over single speed bumps, which is a non-trivial complex motion. One major aim of the study is to investigate the effect of the anti-roll bar upon vehicle body dynamics, while negotiating such traffic calming features. Numerical predictions are made with an intermediate vehicle model, whose results conform well to the actual vehicle tests. These results seem to suggest that events caused by truncated speed bumps can have implications for design of anti-roll bars from a ride comfort viewpoint, over and above the usual requirements dictated by safe vehicle handling.

The paper attempts to provide an integrated framework for the objective assessment of the transient handling responses of non-linear vehicles. The ultimate aim of the proposed framework is the characterization of such responses as neutral or under/over-steering. A new methodology is employed, which has previously been applied for the classification of the transient response of linear vehicles. The success of the proposed method is judged based on its robustness, the consistency of the results, and their practical implications. Furthermore, the results are compared with the findings of traditional approaches for the characterization of the steady-state and transient handling behaviour. The corresponding discussion reveals the agreement between the approaches, but also highlights the slightly different definition of the neutrally steering vehicle, as perceived by the proposed method.

Minimization of parasitic losses in the internal combustion (IC) engine is essential for improved fuel efficiency and reduced emissions. Surface texturing has emerged as a method palliating these losses in instances where thin lubricant films lead to mixed or boundary regimes of lubrication. Such thin films are prevalent in contact of compression ring to cylinder liner at piston motion reversals because of momentary cessation of entraining motion. The paper provides combined solution of Reynolds equation, boundary interactions, and a gas flow model to predict the tribological conditions, particularly at piston reversals. This model is then validated against measurements using a floating liner for determination of in situ friction of an engine under motored condition. Very good agreement is obtained. The validated model is then used to ascertain the effect of surface texturing of the liner surface during reversals. Therefore, the paper is a combined study of numerical predictions and the effect of surface texturing. The predictions show that some marginal gains in engine performance can be expected with laser textured chevron features of shallow depth under certain operating conditions.

OsteoArthritis is a debilitating disease throughout the developed world, causing significant loss of quality of life to individuals and damaging economies, the imaging system described in this paper has the potential to provide an objective means of measuring and reporting lesion dimensions and providing a machine readable data archive for future study. Existing imaging methodologies have been reviewed and contrasted and despite certain limitations the optical method proposed has the potential to address the issues highlighted to date. The preliminary depth measurement results with an accuracy of 200 µm±6% suggests a potential system for the objective reporting of tissue degradation. It is also envisaged that the bio tribological performance may be inferred from the tissue surface condition as image by the proposed system.

The paper describes the importance of reducing frictional losses in internal combustion (IC) engines, thereby improving engine efficiency. One of the main sources contributing significantly to engine friction is the interaction between the piston compression and oil rings and the cylinder bore/liner. Improving the tribological performance in these conjunctions has the greatest potential for performance improvement in the IC engine. Traditionally, the approaches used to tackle this problem have relied heavily on empirical engineering judgement. These have resulted in many inconclusive studies, involving a large number of alternatives, including the introduction of cylinder liners with surface modification work and/or with special coatings. This paper highlights a fundamental investigation of surface modification and coating and its impact on frictional performance. The study combines numerical and experimental approaches. Very good agreement is found between the conclusions of numerical predictions and those of engine test bed work.

An analysis of the mechanism of tyre contact force generation under transient conditions is presented. For this purpose, two different versions of a brush model are used, both with inertial and viscoelastic properties. The first model consists of independent bristles, while the second, with a more realistic scenario, introduces viscoelastic circumferential connections between the sequential bristles, which affect the lateral degrees of freedom. Friction between the tyre and the ground follows an experimentally verified stick-slip law. For the model with independent bristles, the state of each bristle at any instant of time depends only on the state of the same bristle at a previous time step. In the second model, the instantaneous state depends on the state of the same bristle at the preceding time step, as well as on the state of the two adjacent bristles at the same time. Simulation results reveal the differences between the two models and most importantly show how transient friction force generation may differ substantially from steady state predictions. The findings suggest that transient tyre behaviour should not be attributed solely to the contributions of the flexible belt and carcass. On the contrary, the observed transience in the neighbourhood of the contact patch should also be taken into account.

Enterprise architecture is the discipline of describing and analysing the relationship between an enterprise's objectives and purpose, and the system of systems which the enterprise uses to help achieve those objectives. This paper makes the case for the importance of aesthetics in enterprise architecture. It proposes an enterprise architectural modelling language which addresses enterprise form, purpose and aesthetics. This language is a meta-model extension of SysML which uses the power of SysML to address the engineering aesthetic of enterprise architecture. The paper is based on work carried out for the UK Ministry of Defence's Integration Authority to develop an “Integration Services Support Environment” (ISSE). ISSE uses the enterprise architecture modelling language to enable the consistent description, and hence analysis, of a large and heterogeneous system of systems. ISSE itself has been developed as a enterprise architecture modelling tool and as a repository of interconnected models of MoD's enterprise.

The behaviour of tyres under transient handling manoeuvres is studied with the aid of a newly developed model. The model consists of a discretized flexible belt with damping and inertia, connected to the rim by viscoelastic elements representing the carcass. In the neighbourhood of the contact patch, the belt is connected to a separate discretized viscoelastic tread with inertia. A separate algorithm taking into account the radial deflection of the carcass elements is used for the calculation of the contact pressure distribution along the contact patch. Friction follows a stick—slip law taking into consideration the velocity of tread elements, the normal force and the unequal coefficients of friction in the lateral and longitudinal directions. The model seems capable of generating transient forces and moments including the phase lags observed under time-varying kinematic excitations.

The paper presents a six-degree-of-freedom (6-DOF) multi-body vehicle model, including realistic representation of suspension kinematics. The suspension system comprises anti-squat and anti-dive element. The vehicle model is employed to study the effect of these features upon combined bounce and pitch plane dynamics of the vehicle, when subjected to bump riding events. The investigations are concerned with a real vehicle and the numerical predictions show reasonable agreement with measurements obtained on an instrumented vehicle under the same manoeurves.

The main function of piston compression ring is to seal the space between the piston and the liner, acting as slider bearing, subjected to reciprocating motion. The compression ring-cylinder liner conjunction has been extensively studied and it is responsible for a significant part of the total frictional parasitic power losses of an engine. Paradoxically, the required sealing function of the compressions ring can result in increased friction. Therefore, in order to improve engine efficiency, it is important to fundamentally understand and subsequently palliate some of these losses. Another problem in any slider bearing-type contact is lubricant film rupture and cavitation in the conjunctional outlet zone, reducing load carrying capacity and potentially leading to erosion damage. A cavitation model presented in two-phase flow CFD analysis of the ring-bore contact under isothermal conditions. Liquid flow is modelled as a continuous phase and a dispersed phase, representing cavitation bubbles. Many of the fundamental physical processes assumed to take place in cavitating flows are incorporated into the model.

Observes that the provision of intelligent control is seen as the logical extension of existing seat‐belt and airbag systems for passenger vehicles to optimize secondary safety performance. Demonstrates the need for discrete information about the driver/passenger in the vehicle in order to provide optimal control of seat‐belt pre‐tensioning; seat‐belt reel‐out (post‐crash pulse); and air bag inflation timing and/or rate. Finds, from system modelling and statistical crash data, that such information as occupant mass and position with respect to vehicle interior and steering wheel are important parameters in the optimal control of the above integrated systems. Justifies these needs and shows that the design of a Smart Seat provides the necessary data. Explains that the design incorporates sensor systems, using a Mechatronic integrated approach.

Changes in the consumer market have resulted in many companies allocating considerable resources to their logos and trademarks with a subsequent need for high quality product packaging. Looks at design work undertaken for a system for quality control of printing images on packaging materials. Discusses the need to integrate the print process within the box making machine and the challenge of designing print machinery that can utilise environmentally friendly recycled paper. It looks at the problems of sensing and data acquisition from high through put machines and describes the two main aspects of print quality ‐colour quality and print registration and the methods of gathering this information. Concludes that a mechatronic approach is required for quality control of print images on packaging materials with an end product comprising sensors, machine vision, microprocessors and ultimately machine control and actuation.

This Vehicles sold in the US and Europe have to be equipped with a Diagnostics, called On-Board Diagnostics (OBD), which monitor the performance of various elements of the emission control system. The driver is informed as to any failures by the use of a Check Engine Light on the dashboard of the vehicle and then should return the vehicle to the dealership for rectification. The vehicle manufacturer's aim is to ensure that the Check Engine Light is only illuminated for legitimate failures. For the calibration of an On Board Diagnostics there needs to be sufficient separation between the response of a good sensor and a failed sensor, the setting of this threshold should be based upon a statistical model of the data so that the predicted failures rate can then be determined. By applying confidence limits to the models allows the engineer to understand how additional data points will effect the calculation of the failure threshold. This gives the engineer the ability to determine the tradeoff between the number of data points and a confidence in the estimated statistical model.

The regime of lubrication changes in a transient manner in many load bearing conjunctions. This is particularly true of any conjunction which is subjected to changes in contact kinematics as the result of stop-start or motion reversals and loading. One such conjunction in the IC engine is the piston-bore contact. A repercussion of these transient events under otherwise perceived steady operating condition is the underlying changes in the mechanisms giving rise to engine efficiency, such as parasitic losses, mainly due to friction. Understanding the nature of these losses is the prelude to any form of palliation. A single cylinder motocross motorbike engine’s cylinder barrel is redesigned to accept wet liners with various incorporated instrumentation. The paper describes one such barrel which incorporates an instrumented floating liner for the purpose of measurement of in-cylinder friction. The principle and design of the floating liner is described. A series of tests are carried out in order to ensure the operational integrity and repeatability of the device. The basic test includes motorised running of the engine without the cylinder head installed. This renders simplified motion of the liner, subject to resistance by friction only. In a sense, under this type of motion, the liner should undergo a form of simple harmonic motion, which is verified using a number of suitably positioned accelerometers. Some more representative tests are reported under motorised conditions with the cylinder head installed. Thus, the effect of chamber pressure is introduced. However, with no combustion pressure, heat output and resulting side forces, a better understanding of tribological conditions is accrued owing to the reduced physical interactions. The results show the dominance of a mixed regime of lubrication at the dead centre reversals.

Both the piston ring and cylinder bore experience wear throughout their life cycle. Therefore change occurs in the geometrical profile and topography of the ring. In addition, coating on the ring is also subject to wear, thus altering the physical/mechanical property of the contacting surface. These changes affect the tribological performance of the ring-bore conjunction. Geometrical changes often alter the ring contacting profile, which affects the entrainment of the lubricant into the conjunction. This can affect the regime of lubrication, thus mechanisms that contribute to friction. Wear of surfaces also plays some role in boundary friction in terms of topographical changes as well as surface properties such as hardness and asperity shear strength. Most analysis does not take into account changes in tribological conditions which occur as the result of these salient changes in practice. The paper intends to bridge this gap in the fundamental knowledge and provide explanations for some in-field experiences noted with wear of a compression ring in a typical engine test. The method of solution used is based on the average flow factors which are indicative of entrainment of the lubricant through the rough ring-bore conjunction. This approach was initiated by Patir and Cheng, for which realistic topographical parameters according to the stage of the wear process is included. Changes in friction and fuel energy consumed are predicted.

Architecting has become an important discipline within the broader context of systems engineering. The lack of a common understanding of the discipline amongst practitioners and other stakeholders, particularly in broad communities, can result in confusion, misunderstanding and inefficiencies. Methods and principles from the Soft Systems Methodology (SSM) are used to define a method for investigating different approaches to systems and system of systems architecting, which we characterize as distinct ‘belief systems’. This method is applied to a number of such ‘belief systems’ encountered in applied systems architecting with the aim of clarifying their key features and promoting mutual understanding across different architecting communities.

Vehicles sold in the US and Europe have to be equipped with a Diagnostics, called OnBoard Diagnostics (OBD), which monitor the performance of various elements of the emission control system. The driver is informed as to any failures by the use of a Check Engine Light on the dashboard of the vehicle and then should return the vehicle to the dealership for rectification. The vehicle manufacturer's aim is to ensure that the Check Engine Light is only illuminated for legitimate failures. For the calibration of an On Board Diagnostics there needs to be sufficient separation between the response of a good sensor and that of a failed sensor the setting of this threshold should be based upon a statistical model of the data so that the predicted failures rate can then be determined. In practice generating a statistical model which is appropriate for the setting of fault thresholds can prove difficult. In this paper this issue is resolved by making use of an extreme statistics method, Generalised Pareto Distribution model to allow a threshold for an Airflow Sensor diagnostic to be set.

The Ultra Compact Combustor is a design that integrates a turbine vane into the combustor flow path. Because of the high fuel-to-air ratio and short combustor flow path, a significant potential exists for unburned fuel to enter the turbine. Using contemporary turbine cooling vane designs, the injection of oxygen-rich turbine cooling air into a combustor flow containing unburned fuel could result in heat release in the turbine and a large decrease in cooling effectiveness. The current study explores the interaction of cooling flow from typical cooling holes with the exhaust of a fuel-rich well-stirred-reactor operating at high temperatures over a flat plate. Surface temperatures, heat flux, and heat transfer coefficients are calculated for a variety of reactor fuel-to-air ratios, cooling hole geometries, and blowing ratios. Results demonstrate that reactions in the turbine cooling film can result in increased heat transfer to the surface. The amount of this increase depends on hole geometry and blowing ratio and fuel content of the combustor flow. Failure to design for this effect could result in augmented heat transfer caused by the cooling scheme, and turbine life could be degraded substantially.

The Nb containing Ni-based superalloys used for the production of large castings are highly sensible to the formation of macrosegregation defects like freckles and white spots. Production cost can be reduced by better prediction of the freckle formation. The most accepted freckling criterion is the one based on the Rayleigh number, which requires accurate determination of the partition coefficients for the solute elements. In this work, the partition coefficients of Nb and Fe on the ternary system Ni-Fe- Nb were studied by experimental measurements and by thermodynamic calculations. Modified DTA experiments were performed for model alloys, and a thermodynamic database for the Ni-Fe-Nb ternary system was developed. Most of the calculated partition coefficients using the developed model agree well with the experimental data. One exception to this, as will be discussed later, is the partitioning coefficient of Fe for the alloy containing 36 wt. %Fe. cycle efficiency 1 . The large rotor discs required need to be made of Nb containing Ni based superalloys to avoid over aging 2 and withstand the higher operation temperatures. However, Nb containing alloys tend to present macrosegregation defects like freckles, caused by downward flow of segregated heavier interdendritic liquid, in the mushy zone of the u-shaped metal pool characteristic of the Vacuum Arc Remelting (VAR) ingots 3 . In order to avoid freckles special melting techniques at increased cost have been developed to produce the large VAR ingots, which include multiple stages of remelting combined with liquid metal refining steps and rigorous computer control of the process 4, 5 . Production cost could be reduced by a better prediction of freckle formation using a criterion that accurately describes the physical phenomenon. The criterion most widely used is based on the Rayleigh number concept and is strongly influenced by the density change of the interdendritic liquid, requiring accurate determination of the partition coefficients of solute elements and their variation with the evolution of the solidification. As Ni based superalloys are usually multicomponent, computational modeling can provide tractable approaches to gain insights into how the partition coefficients change as a function of temperature, composition and processing conditions. The main objective of this work is to study the partition coefficients of Nb and Fe in the model Ni-base alloys and compare the measurements with the theoretical predictions. The Ni-based alloy samples were prepared by mixing and melting the raw elements using a tri-arc bottom furnace. The partition coefficients were measured on samples by modified DTA experiments (MDTA) on which the samples were quenched while solidifying. Two databases were used to predict partition coefficients: Ni-Fe-Nb system obtained by this work and the TTNi6 Ni-database 6 . The thermodynamic database of the Ni-Fe- Nb ternary system has not been reported in the literature, and was developed in the present work. The calculations were performed using two different methods: (i) the equilibrium solidification model 7 and (ii) the Scheil model 8 .

The paper presents a novel method for the measurement of lubricant film thickness in the piston-liner contact. Direct measurement of the film in this conjunction has always posed a problem, particularly under fired conditions. The principle is based on capturing and analysing the reflection of an ultrasonic pulse at the oil film. The proportion of the wave amplitude reflected can be related to the thickness of the oil film. A single cylinder 4-stroke engine on a dyno test platform was used for evaluation of the method. A piezo-electric transducer was bonded to the outside of the cylinder liner and used to emit high frequency short duration ultrasonic pulses. These pulses were used to determine the oil film thickness as the piston skirt passed over the sensor location. Oil films in the range 2 to 21 μm were recorded varying with engine speeds. The results have been shown to be in agreement with detailed numerical predictions.

This paper presents a detailed 4×4 off-road vehicle modelling method, based on a multi-physics approach. A full drivetrain system including all aspects of rotational inertial dynamics, friction, damping and stiffness properties is integrated with a fourteen-degrees-of-freedom vehicle model including body dynamics, kinematics, suspension and wheel dynamics as well as the terramechanical phenomena between tyres and soft soils. The interaction between all these modules is implemented in the MATLAB/SIMULINK/SimDriveline environment. The concepts of modularity, flexibility, and user-friendliness were emphasized during model development. The model is developed in order to provide design engineers with the capability to investigate effects of component selection and to develop control systems and automatic optimization processes for off-road 4×4 vehicles. While the modelling approach can be used for a wide variety of operating conditions, the present work focuses on the analysis of the contribution of different aspects on the off-road traction of 4×4 vehicles.Copyright © 2006 by ASME

Network security starts at the top level. Threats can be thought of in 3 categories: disruption, loss and reputational damage. Always understand the risks that these threats brings. As of protection to these threats, protect the end points and don't just rely on signature based detection alone. Also, security monitoring needs to be automated. Detection systems must include anomaly based systems. Finally, educate and the train the network users.

A Jaguar Car engine is used to provide data for modelling the throttle body, engine pumping and manifold body. Based on the gas law of the intake dynamics, input/output variables are identified and used to train a neural network. Various structures are compared and assessed. The best structure is then used for fault detection. A neural network observer is developed and error stability is assessed. Two fault scenarios are considered.

The paper studies the effect of torsional fluctuations resident on the automotive transmission input shaft upon the rattle phenomenon due to engine orders, as well as transmitted torque variations from any engaged gear pair. Speed variations interrupt the orderly meshing of the idling gears, thus causing impulsive action emanating as rattle. This is a Noise, Vibration and Harshness (NVH) phenomenon of significant concern to industry. The engaged (selected) gear pair teeth are subject to moderate to high loads, thus a thermo-mixed elastohydrodynamic regime of lubrication ensues. Unlike the idle gear pairs, where lightly loaded hydrodynamic conditions prevail, the elastohydrodynamic regime of lubrication ensures reduced teeth separation effects. Both types of lubricated conjunctions abound in a model of a 7-speed transmission system. The numerical predictions agree well and complement measured performance on an engine bed - transmission rig of a front wheel drive vehicle. The paper uses a non-dimensional parameter - impulsion ratio - which relates gear dynamics to the prevailing conditions in the lubricated conjunctions, showing the critical and often conflicting role that lubricant rheology plays in the promotion or palliation of rattle. Furthermore, it objectively demarcates the boundary between low intensity rattle of frequent teeth pair separations from high intensity double-sided teeth impacts with ensuing torque reversals.

A comprehensive computer model is devised for the simulation of AWD off-road vehicle dynamics. Particular attention has been paid to the modelling of various visco-lock devices, including the viscous couplings and visco-lock limited-slip differentials. These devices are represented by fully parameterised physical models which capture the torque transmission mechanism represented by various thermodynamic, hydrodynamic, structural and mechanical modules. The characteristics of these devices can easily be altered so that comparisons can be made between different types. In addition, the influence of a wide range operating conditions, vehicle design parameters and tyre characteristics can also be made over various deformable soils.

This paper presents a 14-DOF mathematical model of an off-road vehicle, integrating terramechanics of tyre soil contact and vehicle dynamics. The model also includes all the other important sub-systems, such as the engine, driveline, steering and suspension systems. Different simulations are carried out, based on standard test manoeuvres, to investigate 4 ? 4 vehicle handling performance under both transient and steady-state conditions. The results show better handling performance on clay than on loam and sand. This is mainly due to the high shearing strength of clay soil, compared with that of loam and sand.

The United States Air Force is currently pursuing a national program to develop the technology necessary to build a single staged aircraft capable of flying from conventional runways into orbit. This vehicle, the National Aerospace Plane (NASP), will use airbreathing propulsion to accelerate through hypersonic speeds to orbital velocities. In order to achieve the aerodynamic and propulsive efficiencies necessary to accomplish this goal, the vehicle forebody must be used as a precompression surface for the engine flowpath. This results in a thick boundary layer which must be bled-off or ingested by the engine. A computational model for thickening boundary layers with mass addition is developed. The phenomena of uniform injection into a two-dimensional supersonic stream and subsequent boundary layer growth downstream is discussed. Analysis of the injection region provides the thickness of the boundary layer just aft of injection. An injection region velocity profile is then used to approximate the boundary layer profile just aft of injection and is input into a finite- difference boundary layer code. Downstream profiles and thicknesses are calculated and compared to experimental results. The computational model developed here provides a tool for the design of a boundary layer generation system for hypersonic engine inlet testing. This mass addition system is needed to simulate the boundary layer developed on the forebody of hypersonic vehicles. Theses. (aw)

Simulation, or the use of models, has been successfully applied to engineering problems for several years. The acceptance of simulation as a working tool by management planners has been mixed, at best. In fact, in comparison to the number of engineers who use simulation, management planners who make use of it are in the minority. During the past five years there have been several applications of simulation by management planners. However, the number of models that ended up in the tool kit of top management are few. This paper discusses the role of simulation in management planning at The Boeing Company, Seattle, Wash., and suggests some useful guidelines.

This paper describes high frequency radiated noise from hollow driveshaft tubes, caused by impulsive torque input into the drivetrain system; a phenomenon referred to as clonk. The annoying metallic nature of clonk and its perception as an indication of low quality manufacture has been a major concern to the automobile industry, particularly for heavy vehicles. This has led to a fundamental study of the mechanisms for the initiation of the phenomenon and their causal roots, highlighted in this paper. Various methods of palliation are also indicated and their effectiveness ascertained.