bluuebunny/crossref_metadata_2025 huggingface dataset:
The stability of motorcycles under acceleration and braking
Authors: Limebeer D. J. N. , Sharp R. S. , Evangelou S
Published: April 2011

A comprehensive study of the effects of acceleration and braking on motorcycle stability is presented. This work is based on a modified version of a dynamic model presented earlier, and is thought to be the most comprehensive motorcycle dynamic model in the public domain. Extensive use is made of both non-linear and linearized models. The models are written in LISP and make use of the multibody modelling package AUTOSIM. There is novelty in the way in which control systems have been used to control the motorcycle drive and braking systems in order that the machine maintains desired rates of acceleration and deceleration.

The results show that the wobble mode of a motorcycle is significantly destabilized when the machine is descending an incline or braking on a level surface. Conversely, the damping of the wobble mode is substantially increased when the machine is ascending an incline at constant speed, or accelerating on a level surface. This probably accounts for the pleasingly stable ‘feel’ of the machine under firm acceleration.

Except at very low speeds, inclines, acceleration and deceleration appear to have little effect on the damping or frequency of the weave mode. Non-linear simulations have quantified the known difficulties to do with rear tyre adhesion in heavy braking situations that are dominated by rear wheel braking.
Laser short-pulse heating: Three-dimensional consideration
Authors: Yilbas B. S.
Published: April 2011

Non-equilibrium energy transport takes place in solids once the laser pulse duration reduces to picoseconds or less. It is this energy transfer mechanism that defines the laser interaction process and therefore the rate at which the material is heated through the collisional process. In the present study, laser short-pulse heating of a gold surface is considered. An electron kinetic theory approach is introduced to model the energy transport process in three dimensions. The governing equation of energy transport is solved numerically, and the electron and lattice site temperatures are predicted. In order to validate the electron kinetic theory predictions, a two-equation model is employed to compute the temperature field in the substrate material. It is found that energy transport due to the diffusional process is unlikely during the heating period considered at present. The predictions of electron kinetic theory agree well with the results obtained from the two-equation model.
Robust Stability with System Uncertainties
Authors: Whalley A , Ebrahimi M
Published: April 2011

Multivariable system models in the form of parameterized, impedance, matrix quadratic realizations are considered. System uncertainties in the form of mass-inertia or damping variations are acknowledged. Simple proportional controller models are proposed and the effect of model variations on the stability of the closed-loop system is investigated. Frequency domain methods are employed to predict the relative stability condition of the system. Conventional stability margin measures may be invoked while adjusting the controller design parameter to an appropriate setting.
Axial crushing force of externally fibre-reinforced metal tubes
Authors: Wang X , Lu G
Published: April 2011

Based on the classical Alexander solution for the axial collapse of bare metal tubes, a theoretical model is presented to predict the mean crushing force of arbitrarily fibre-reinforced metal tubes with a ring collapse mode. The derived mean crushing force and length of the local folding wave are more reasonable and are in better agreement with the experiments than previously obtained. The effect of wrapping direction of the reinforcing fibres is studied. This model for predicting the static mean crushing force can be extended for the dynamic mean crushing force of fibre-reinforced metal tubes under axial impact load.
Image sequences and wavelets for vibration analysis: Part 1: Edge detection and extraction of natural frequencies
Authors: Patsias S , Staszewski W J , Tomlinson G R
Published: April 2011

The paper presents the application of the wavelet edge detection algorithm for structural vibration analysis based on image sequences. A number of different edge detection operators are briefly discussed and illustrated using a simple image example. The wavelet-based edge detection algorithm is then used to identify natural frequencies of a simple cantilever beam. The paper discusses a number of important issues that need to be confronted when using image sequences for vibration analysis. These include correspondence of image features from image to image and image calibration. The paper compares the natural frequencies obtained using such an approach and also another non-contact method and finds them in good agreement.
Image sequences and wavelets for vibration analysis: Part 2: Extraction of modal dampings and modeshapes
Authors: Patsias S , Staszewski W J , Tomlinson G R
Published: April 2011

The paper presents the extraction procedure for modal damping and modeshapes from image sequences obtained through the use of optical measurements. The modal dampings are extracted from the image sequence used to identify a cantilever's natural frequencies through the use of the continuous wavelet transform. The identification of the first five vibration modeshapes of the cantilever is attempted. The differences between the theoretical and experimental modeshapes are tracked back to the experimental set-up and a procedure that compensates for this effect is introduced and proved to be successful. The modal assurance criterion (MAC) is computed for the five modes, indicating high correlation for the first four modes, while the fifth was not possible to identify, due to insufficient spatial resolution.

The wavelet transform plays a central role, since it is involved in every stage of the analysis: image edge detection, modeshape extraction, natural frequencies identification and modal damping extraction from multi-degree-of-freedom (MDOF) decays. This paper discusses the issues that need to be tackled with optical measurements, such as temporal and spatial resolution of the image sequence acquisition.
Plate subjected to an out-of-plane follower force
Authors: Genin J , Xu W
Published: April 2011

The stability of bending-torsional equilibrium of a uniform plate subjected to an out-of-plane follower force is studied in this paper. The resulting system approximates to a wing subjected to the thrust of a jet engine. Attention is focused on the determination of the dynamic stability of the wing as a function of engine thrust. Criteria are established for the determination of the maximum allowable value of the engine thrust.
Elastic stress waves of cylindrical rods subjected to rapid energy deposition
Authors: Zheng J , Xu P , Fu Q , Taleyarkhan R P , Kim S H
Published: April 2011

Rapid energy deposition into targets and beam absorbers in a high-energy accelerator leads to a temperature rise at an enormous rate, giving rise to thermally induced stress waves. Understanding and predicting the resulting stresses are crucial for robust design and safe operation of such devices. In this paper, closed-form expressions for the induced stresses in cylindrical rods subjected to rapid partial energy deposition have been directly derived; they are then used to estimate the highest stress of long cylindrical absorbers and to test the accuracy of thermal shock simulation using finite element analysis (FEA) codes. Characteristics of such stresses were discussed in detail. It was found that ANSYS may produce accurate details in thermal shock simulation if element size and time step used in the simulation model meet the criteria proposed by Zheng and co-workers in another paper.
A new upper bound solution for a hollow cylinder subjected to compression and twist
Authors: Alexandrov S , Tzou G-Y , Hsia S-Y
Published: April 2011

The upper bound technique is adopted to investigate the effect of angular velocity on the load required to compress a circular hollow cylinder between rough parallel plates. The kinematically admissible velocity field accounts for the asymptotic behaviour of the actual velocity field in a vicinity of the friction surface. The theoretical solution is illustrated by numerical examples for different geometrical parameters and friction factors. In particular, the variations in work rate, torsion moment and compression force with the dimensionless angular velocity are shown.
A new technique for the control of a weak shock discharged from a tube
Authors: Kim H D , Kweon Y H , Aoki T , Setoguchi T
Published: April 2011

A shock wave discharged from a tube leads to an impulsive noise that is similar to a sonic boom. The impulsive noise has often been a major factor in deterioration of the performance of flow devices and has hazardous effects on human beings. The objective of the current work is to develop a new technique for the control of the impulsive wave. Experiments using a simple shock tube were carried out to investigate the effect of a cavity/helical vane system on the magnitude of an impulsive wave. The results showed that the magnitude of the impulsive wave was influenced by the detailed configuration of the helical vane inside the cavity which was installed at the exit of a tube. The results of the tests with and without the helical vane were compared to validate the effectiveness of the present control technique. The experimental data showed that the present cavity/helical vane system reduced the peak pressure of the impulsive wave up to about 50 per cent, compared with a straight tube, and was suitable for alleviating the magnitude of the impulsive wave.
Model building and verification for active control of microvibrations with probabilistic assessment of the effects of uncertainties
Authors: Aglietti G S , Langley R S , Rogers E , Gabriel S B
Published: April 2011

Microvibrations, generally defined as low-amplitude vibrations at frequencies up to 1 kHz, are of critical importance in a number of areas. It is now well known that, in general, the suppression of such microvibrations to acceptable levels requires the use of active control techniques which, in turn, require sufficiently accurate and tractable models of the underlying dynamics on which to base controller design and initial performance evaluation. Previous work has developed a systematic procedure for obtaining a finite-dimensional state-space model approximation of the underlying dynamics from the defining equations of motion, which has then been shown to be a suitable basis for robust controller design. In this paper, the experimental validation of this model prior to experimental studies is described in order to determine the effectiveness of the designed controllers. This includes details of the experimental rig and also the use of methods for assessing the safety of the resulting structure against uncertain parameters.
New passive balancing algorithm for high-density hard disk drives
Authors: Hredzak B , Guo G
Published: April 2011

One of the major sources of vibrations in hard disk drives (HDDs) is unbalance caused by an uneven distribution of the mass on the rotational part of the HDD. Vibrations are limiting the increase in the storage density of the HDDs; therefore it is of paramount importance to identify major sources of vibrations and to reduce them to the minimum level. This paper proposes a new passive balancing algorithm which can achieve significant reduction in the HDD unbalance at low cost and with a high yield rate. The unbalance reduction is achieved using a balancing ring with a large number of holes which are used for the placement of balancing masses of a given weight. The optimum number and position of the balancing masses is then found in order to reduce the residual unbalance to minimum level. Guidelines on optimum selection of the correction mass are also proposed.
Diffusion characteristics of a plane jet discharged in a wavy crossflowing stream
Authors: Abdel-Rahman A A , Eleshaky M E
Published: April 2011

an experimental investigation has been undertaken to study the effect of a wavy crossflow on a plane jet discharged vertically downwards in a water channel. Two groups of experiments were performed: one group for a jet discharged into a uniform crossflow; the second group for a jet discharged into a wavy crossflow. Experiments were conducted for four jet-to-crossflow-velocity ratios. For each experiment, measurements using a laser Doppler anemometry system were made at six stations downstream of the exit of the jet nozzle. During the course of the experiments, the channel flow velocity was maintained fairly constant, and the wave generated in the channel was not very steep. The results revealed that the oscillatory motion associated with the waves has a significant effect on both the mean and the turbulent velocity fields. The mean velocity profiles were found to have no maximum value, compared with those of a uniform crossflow. The effect was most pronounced in the zone of flow establishment, where a region of intense fluid mixing arises, resulting in a significant shortening of the zone and a rapid development of the jet flow.
Numerical simulation of the stalled flow within a vaned centrifugal pump
Authors: Guleren K M , Pinarbasi A
Published: April 2011

The main goal of the present work is to analyse the numerical simulation of a centrifugal pump by solving Navier-Stokes equations, coupled with the ‘standard k-∊’ turbulence model. The pump consists of an impeller having five curved blades with nine diffuser vanes. The shaft rotates at 890r/min. Flow characteristics are assumed to be stalled in the appropriate region of flowrate levels of 1.31-2.861/s. Numerical analysis techniques are performed on a commercial FLUENT package program assuming steady, incompressible flow conditions with decreasing flowrate. Under stall conditions the flow in the diffuser passage alternates between outward jetting when the low-pass-filtered pressure is high to a reverse flow when the filtered pressure is low. Being below design conditions, there is a consistent high-speed leakage flow in the gap between the impeller and the diffuser from the exit side of the diffuser to the beginning of the volute. Separation of this leakage flow from the diffuser vane causes the onset of stall. As the flowrate decreases both the magnitude of the leakage within the vaneless part of the pump and reverse flow within a stalled diffuser passage increase. As this occurs, the stall-cell size extends from one to two diffuser passages. Comparisons are made with experimental data and show good agreement.
Simulation of mixed convection heat transfer to carbon dioxide at supercritical pressure
Authors: He S , Kim W S , Jiang P X , Jackson J D
Published: April 2011

Computational simulations of turbulent mixed convection heat transfer experiments using carbon dioxide at supercritical pressure have been performed by solving the Reynolds averaged transport equations using an elliptic formulation. A number of two-equation low Reynolds number turbulence models have been used and the results have been compared directly with the experimental data. It has been shown that most of the models were to some extent able to reproduce the effects of the very strong influences of buoyancy on heat transfer in these experiments. However, the performance of the models varied significantly from one to another in terms of the predicted onset of such effects.
Measurements of thermal radiation in ultralight metal foams with open cells
Authors: Zhao C Y , Lu T J , Hodson H P
Published: April 2011

Highly porous ultralightweight cellular metal foams with open cells have attractive mechanical, thermal, acoustic and other properties and are currently being exploited for hightemperature applications (e.g. acoustic liners for combustion chambers). In such circumstances, thermal radiation in the metal foam becomes a significant mechanism of heat transfer. This paper presents results from experimental measurements on radiative transfer in Fe-Cr-Al-Y (a steel-based high-temperature alloy) foams having high porosity (95 per cent) and different cell sizes, manufactured at low cost from the sintering route. The spectral transmittance and reflectance are measured at different infrared wavelengths ranging from 2.5 to 50 μ, which are subsequently used to determine the extinction coefficient and foam emissivity. The results show that the spectral quantities are strongly dependent on the wavelength, particularly in the short-wavelength regime (less than 25 μ). While the extinction coefficient decreases with increasing cell size, the effect of cell size on foam reflectance is not significant. When the temperature is increased, the total extinction coefficient increases but the total reflectance decreases. The effective radiative conductivity of the metal foam is obtained by using the guarded hot-plate apparatus. With the porosity fixed, the effective radiative conductivity increases with increasing cell size and increasing temperature.
Pressure loss and heat transfer mechanisms in a lattice-frame structured heat exchanger
Authors: Kim T , Hodson H P , Lu T J
Published: April 2011

A novel heat exchanger medium, a high-porosity (0.938) lattice-frame material (LFM), has been introduced for possible use in mechanically and thermally loaded heat exchanger applications. The LFM is made up of circular cylinders, forming tetrahedral unit cells. This paper describes the results of experiments and numerical simulation leading to a detailed understanding of the flow structure, pressure loss and heat transfer mechanisms.

It is shown that the circular LFM struts are responsible for approximately 85 per cent of the overall pressure losses in the unit cell by means of form drag at high Reynolds number. The LFM causes heat removal from the substrate by promoting flow mixing and also contributes to the overall heat transfer by convection from the strut surfaces. If a high thermal conductivity material is used, the strut and substrate contribute 57 and 43 per cent respectively of the total heat transfer. Steady numerical simulations show that a porosity of approximately 0.8 provides the best heat transfer performance for a fixed mass flowrate. However, the pressure loss monotonically increases as the porosity decreases within a range of porosity, 0.7 ≤ ε ≤ 0.938.
Performance of a variety of low Reynolds number turbulence models applied to mixed convection heat transfer to air flowing upwards in a vertical tube
Authors: Kim W S , Jackson J D , He S , Li J
Published: April 2011

The study reported here is concerned with mixed convection heat transfer to air flowing upwards in a vertical tube. Computational simulations of experiments from a recent investigation have been performed using an ‘in-house’ code which was written specifically for variable-property, developing, buoyancy-influenced flow and heat transfer in a vertical passage. The code incorporates a selection of two-equation, low Reynolds number turbulence models. The objective of the study was to evaluate the models in terms of their capability of reproducing the effects on turbulent heat transfer of non-uniformity of fluid properties and buoyancy. Direct comparisons have been made between results from the experimental investigation and those obtained by computational modelling for a range of conditions. The trends of impairment and enhancement of heat transfer owing to the influence of buoyancy found in the experiments were captured to some extent in the simulations using each of the models. However, none reproduced observed behaviour correctly over the entire range of buoyancy influence.
Numerical simulation of heat transfer from a transonic jet impinging on skin for needle-free powdered drug and vaccine delivery
Authors: Liu Y , Kendall M A F
Published: April 2011

In this paper, gas dynamics and temperature distribution of a transient impinging jet, typically used to deliver powdered drug or vaccines ballistically to the skin, have been numerically simulated. Calculations were performed with the unsteady compressible Navier-Stokes equations, solved using a modified implicit flux vector splitting (MIFVS) difference scheme with a modified k-e model. After validation against an experimental underexpanded jet-flow test cast, the code was applied to two biolistic configurations. Firstly, calculated pressure histories were compared with corresponding measurements in an unsilenced biolistic device, with good agreement. Secondly, this calculation was extended to a silenced geometry, with an emphasis on the gas properties immediately above a skin target. A peak stagnation gas temperature of 420°C is revealed within 175 μs of diaphragm rupture. The temperature of the following driver helium gas suddenly drops to below - 100°C before approaching ambient temperature within 1 ms. The effect of this impinging jet on the human skin is subsequently explored by a one-dimensional convection heat transfer model. On the skin surface, a peak fluctuation of [+5.5°C, - 4.5°C] is.recorded during the operation process. Beyond the outer skin layer, called the stratum corneum (i.e. > 10.6μ), temperature deviations from the normal condition are trivial. Therefore, the heat transfer between the biolistic jet and skin is negligible. This result is consistent with pain-free clinical trial observations.
Buckling of Flat Plates Under Bending and Shear
Authors: Featherston C A , Ruiz C
Published: April 2011

Extensive work has been carried out to determine expressions for the critical buckling loads of flat plates under the elementary load cases of shear, compression and bending, and combinations of these three. Existing solutions are based on constant stress levels throughout the plate, but no theoretical solution or design rules exist for more complex situations. Finite element analysis is often therefore used to solve more complicated cases. This paper outlines a programme of work that has been undertaken to compare collapse loads predicted by theoretical, experimental and finite element analysis predicted collapse loads for the case of a flat rectangular plate under combined shear and bending.
Torsional Vibrations in Rotor Shells
Authors: Whalley R , Ebrahimi M
Published: April 2011

Rotors comprising a motor-driven thin cylindrical shell with rigidly attached ends and torsional dampers, all of which are supported on bearings, are investigated. Analysis procedures enabling the variations in the model singularities with parameter changes are outlined. General results are derived indicating that the system damping ratio is maximized under specific operating conditions. A typical high-speed rotor for a paper manufacturing process is considered and analytical and simulation results are presented, confirming the predicted optimum damper settings and thereby minimizing the transient oscillations.
Heat flux measurement techniques
Authors: Childs P R N , Greenwood J R , Long C A
Published: April 2011

Heat flux measurement is used in the field of fluid mechanics and heat transfer to quantify the transfer of heat within systems. Several techniques are in common use, including: differential temperature sensors such as thermopile, layered resistance temperature devices or thermocouples and Gardon gauges; calorimetric methods involving a heat balance analysis and transient monitoring of a representative temperature, using, for example, thin-film temperature sensors or temperature sensitive liquid crystals; energy supply or removal methods using, for example, a heater to generate a thermal balance; and, finally, by measurement of mass transfer which can be linked to heat transfer using the analogy between the two. No one method is suitable to all applications because of the differing considerations of accuracy, sensitivity, size, cost and robustness.

Recent developments including the widespread availability and application of thin-film deposition techniques for metals and ceramics, allied with advances in microtechnology, have expanded the range of devices available for heat flux measurement. This paper reviews the various types of heat flux sensors available, as well as unique designs for specific applications. Critical to the use of a heat flux measurement technique is accurate calibration. Use of unmatched materials disturbs the local heat flux and also the local convective boundary layer, producing a potential error that must be compensated for. The various techniques in common use for calibration are described. A guide to the appropriate selection of a heat flux measurement technique is provided according to the demands of response, sensitivity, temperature of operation, heat flux intensity, manufacturing constraints, commercial availability, cost, thermal disturbance and acceleration capability for vibrating, rotating and reciprocating applications.
New error correction algorithms minimizing residual positional error for a computer integrated error calibration/correction system in computer numerically controlled machine tools
Authors: Pahk H J , Lee S W
Published: April 2011

Linear displacement accuracy is one of the most important factors determining machine tool performance. Software error correction has been generally used for improving the positional accuracy in computer numerically controlled (CNC) machine tools. In this paper, a set of new correction algorithms has been presented for minimizing residual positional errors in CNC machine tools after correction.
Exact dynamic stiffness method for planar natural frequencies of curved Timoshenko beams
Authors: Howson W P , Jemah A K
Published: April 2011

An exact dynamic stiffness matrix, which defines the planar motion of a circularly curved Timoshenko beam member, is developed from the closed-form solution to the governing differential equations. This matrix and a variation of the Wittrick-Williams algorithm are combined in a stiffness formulation in such a way that the required natural frequencies, which correspond to the solutions of a transcendental eigenvalue problem, are converged upon unambiguously, to any desired accuracy, for any plane structure composed of such members. The effects of rotary inertia and shear deflection, uniquely described by the parameters r and s respectively, can be accounted for in any combination. Any particular effect can be neglected by setting the relevant parameter to zero. An example is included that highlights the effects of every possible combination of rotary inertia and shear deflection on the natural frequencies of a simple two-span arch structure, and comparisons are made with published work to confirm the accuracy of the method.
Numerical predictions of a turbulent diffusion flame in a cylindrical combustor using eddy dissipation and flamelet combustion models
Authors: Ma C Y , Mahmud T , Gaskell P H , Hampartsoumian E
Published: April 2011

A mathematical model has been applied to simulate a confined, turbulent natural gas diffusion flame for which measurements were reported in the literature [7]. The combustion is modelled using both eddy dissipation [2] and non-equilibrium, mixedness—reactedness flamelet [6, 20] models. The latter model is based on a laminar flamelet approach originally developed for premixed combustion. The turbulence is represented by a Reynolds stress model based on the differential transport equations for stresses. The computational results are compared with experimental data for gas temperature and species concentrations. The predictions obtained using the flamelet model are found to be in good agreement with measurements, whereas the eddy dissipation combustion model fails to capture the measured trends in the near-burner region. Efforts have been made to improve the quality of the predictions of the latter model by incorporating an extinction criterion [25] and by adjusting the value of the model parameter. Both actions generate predictions similar to that of the flamelet model.
Tangential slip noise of V-ribbed belts
Authors: Dalgarno K W , Moore R B , Day A J
Published: April 2011

This paper reports the results of a study into V-ribbed belt noise generated as a result of tangential belt slip. The results of experimental studies to identify the belt operating conditions associated with belt noise are presented, together with the results of analytical studies to identify the mechanism of noise generation. It is concluded that tangential slip V-ribbed belt noise generation is controlled only by the amount of slip, and that the mechanism of noise generation is harmonic excitation of the fundamental vibration mode of the belt, with stick—slip frictional behaviour providing the impetus for the vibration.
Technical Note: Neural network modelling of the emissions and performance of a heavy-duty diesel engine
Authors: Thompson G. J. , Atkinson C. M. , Clark N. N. , Long T. W. , Hanzevack E
Published: April 2011

Internal combustion engines are being required to comply with increasingly stringent government exhaust emissions regulations. Compression ignition (CI) piston engines will continue to be used in cost-sensitive fuel applications such as in heavy-duty buses and trucks, power generation, locomotives and off-highway applications, and will find application in hybrid electric vehicles. Close control of combustion in these engines will be essential to achieve ever-increasing efficiency improvements while meeting increasingly stringent emissions standards. The engines of the future will require significantly more complex control than existing map-based control strategies, having many more degrees of freedom than those of today.

Neural network (NN)-based engine modelling offers the potential for a multidimensional, adaptive, learning control system that does not require knowledge of the governing equations for engine performance or the combustion kinetics of emissions formation that a conventional map-based engine model requires. The application of a neural network to model the output torque and exhaust emissions from a modern heavy-duty diesel engine (Navistar T444E) is shown to be able to predict the continuous torque and exhaust emissions from a heavy-duty diesel engine for the Federal heavy-duty engine transient test procedure (FTP) cycle and two random cycles to within 5 per cent of their measured values after only 100 min of transient dynamometer training. Applications of such a neural net model include emissions virtual sensing, on-board diagnostics (OBD) and engine control strategy optimization.
Limiting performance of seat belt systems for the prevention of thoracic injuries
Authors: Crandall J. R. , Cheng Z , Pilkey W. D.
Published: April 2011

The theoretically optimal performance of seat belt systems for occupants in automobile frontal crashes is investigated based on a two-mass injury model of the thorax. The performance is measured by thoracic injury criteria which include the maximum chest acceleration, compression and viscous response. The relationship between the best possible performance (limiting performance) of the seat belt system and the distance between the occupant and the interior components of the vehicle is displayed in the form of trade-off curves, which can be used for the evaluation of seat belt performance. The characteristics of the optimal seat belt force and the kinematics of the system are illustrated. The results indicate that the optimal seat belt force is not constant during an impact and that an initial impulse is required. However, constant seat belt force can provide thoracic restraint that is close to the optimal solution.
Performance evaluation of non-edible vegetable oils as substitute fuels in low heat rejection diesel engines
Authors: Prasad C. M. V. , Krishna M V S M , Reddy C. P. , Mohan K. R.
Published: April 2011

Search for renewable fuels such as vegetable oils, in particular non-edible vegetable oils, has become more pertinent in the context of the fossil fuel crisis and vehicle population explosion. The drawbacks associated with vegetable oils for use in diesel engines call for a hot combustion chamber. The concept of the low heat rejection diesel engine is gaining prominence for adopting vegetable oils as substitute fuels for conventional diesel fuel.

Non-edible vegetable oils such as Pongamia oil and Jatropha curcas oil are found to be efective substitute fuels in the low heat rejection diesel engine. EsteriRcation, preheating and increase in injection pressures have been tried for efective utilization of the vegetable oils. Performance parameters such as the brake specific energy consumption (b.s.e.c.) and exhaust gas temperature (EGT) have been reported for varying magnitudes of brake mean efective pressure (b.m.e.p.) with diferent non-edible vegetable oils as substitute fuels. The pollution levels of black smoke and NOx have been recorded. Combustion diagnosis is also carried out with the aid of a miniature piezoelectric pressure transducer and TDC (top dead centre) encoder.
Gear oil influences on efficiency of gear and fuel economy of cars
Authors: Bartz W. J.
Published: April 2011

1. First of all, it should be considered that the fuel consumption of a car depends on a set of parameters only partly related to tribology. Their influence is much more pronounced than that of the lubricant.

2. Only the mechanical losses can be decreased by lubricant-related measures. Therefore, the fuel economy improvement that possibly might be realized is rather limited, especially when taking into account the rather high efficiency of gears.

3. When evaluating the influence of viscosity on fuel consumption, the so-called effective viscosity must be taken into account. This is most important for non-Newtonian oils.

4. Reducing the gear oil viscosity by one SAE viscosity grade will result in fuel consumption reductions of 0.2-1.5 per cent at high temperatures and 0.4-2.5 per cent at low temperatures.

5. Using friction modifiers in gear oils, fuel consumption reductions of between 1.0 and 6.0 per cent are realistic.

6. On the basis of a 50 per cent friction reduction maximum fuel consumption reductions between 1.0 and 5.1 per cent by other gear oils are possible, considering different driving programmes.

7. Tests with a real automobile gear resulted in fuel economy improvements of the order of magnitudes of 1 per cent by other gear oils.

8. The results of measurements confirm in principle the calculated estimations.
A method of measuring the dynamic loads in high-speed timing chains
Authors: Stephenson R , Glennie D , Fawcett J. N. , Hale J. M.
Published: April 2011

This paper describes the design, construction and initial testing of an experimental rig for the measurement of dynamic loading of an automotive timing chain under realistic running conditions. The novel instrumentation system developed for this application is described, together with the mechanical construction of the measurement system. Results are presented for a two-sprocket drive under constant load. Clear variations in chain link tension around the chain loop are shown, and these are explained in terms of position, sprocket run-out and sprocket polygonal action.
Case Study: The development of a sub-3 litre/100 km passenger car
Authors: Deacon M , Horrocks R. W. , Watts M. J.
Published: April 2011

An advanced three-cylinder 12-valve turbocharged direct injection diesel engine was installed in a specially prepared lightweight, low drag Ford Ka. The objective of the exercise was to demonstrate 3.0 1/100 km fuel economy over the EC stage II drive cycle and to look at the sensitivity of vehicle fuel economy with respect to weight, gear ratios, rolling resistance and aerodynamic drag. The engine was prepared on a dynamometer test cell, prior to installation in the vehicle, to optimize its efficiency, particularly around the low speed, part load area, where the engine predominantly operates during the drive cycle. Three vehicles were prepared: two fitted with manual five-speed transmissions, with optimized gear and final drive ratios, and a third vehicle fitted with an electronic constantly variable transmission (CVT). The two manual transmission cars were shown at the Berlin Show in mid-October 1996, publicized as Ka step 1, in support of the launch of this new vehicle. The best experimental results achieved were 3.1 1/100 km with the manual transmission, which could be reduced to below 3 1/100 km with a simulated stop-start strategy, and 3.31/100 km for the CVT. At the very low inertia classes used in this exercise, the effects of transmission ratios, rolling resistance, aerodynamic drag and automatic engine stop-start were found to be more dominant than the effect of weight on fuel consumption.
A multi-reflector headlamp that can produce a diagonal cut-off without a shield
Authors: Yan W , Mao W
Published: April 2011

Inherent in the design of a low-beam (passing-beam) headlamp pattern is a trade-off between providing sufficient lighting for the driver using the headlamp and protecting oncoming drivers from glare. To solve this problem, a multi-reflector (MR) headlamp is presented which has a dual focal length parabolic cylinder construction to utilize fully the light emission of the light source. Also, some segments of the MR have a tilted parabolic cylindrical shape, so a sharp diagonal cut-off line can be realized.
Reduced-order modelling and parameter estimation for a quarter-car suspension system
Authors: Kim C , Ro P. I.
Published: April 2011

This paper presents a new approach to obtaining an accurate simple model for complex mechanical systems. The methodology is applied to a quarter-car suspension system with complex linkage structures. Firstly, a multi-body dynamic model which includes kinematic characteristics is developed. Using a linearization technique, a 32-state linear model for a quarter-car system is obtained. Secondly, model reduction techniques are applied to find a reasonable reduced-order model. The result of the model reduction shows the validity of the two-mass model given that the parameters are correctly identified. The paper presents both an analytical and an experimental way of identifying the parameters of the two-mass system based on the reduced-order model. The identified parameters are shown to vary significantly from component data typically used for the two-mass system depending on kinematic structures of the suspension system. The modelling procedures outlined in this paper provide a precise and efficient way of designing active suspension systems that minimizes a necessary tuning process.
The frontal impact response of a spaceframe chassis sportscar
Authors: Williams T. D. , de Pennington A , Barton D. C.
Published: April 2011

The frontal impact behaviour of a low volume, niche market sportscar with a spaceframe chassis has been investigated using the non-linear finite element code Oasys LS-DYNA3D. In considering the options for crashworthiness improvements, it was first essential to understand and have confidence in the overall structural response that was being predicted. An experimental test programme has supported the finite element predictions and has included the impact testing of typical brazed tubular structures and an automotive wheel and tyre. Results from a 23 000 finite element vehicle model correlate well with the digitized results of a crash test video.
Modelling the monolithic exhaust converter/fuel reformer reactor—a zonal approach
Authors: Chow A , Wyszynski M. L.
Published: April 2011

A two-dimensional mathematical model of a monolithic catalyst support, based on a zonal approach, is developed to describe the heat interactions between the monolith channels. The development of such model is a step towards its incorporation in the complete thermal systems model of the propulsion powerplant. The model conservation equations are discretized using the finite volume method and a numerical solution method is presented. The model is validated using the experimental data available in literature for two cases: a steady state, non-reacting, non-adiabatic two-dimensional case and a transient (warm-up), one-dimensional reacting case. Comparison with literature experimental data showed good agreement. The zonal approach where multi-channel zones are used is demonstrated to provide robust and efficient simulation with significantly reduced simulation times compared with a single channel per zone grid, without introducing large errors.
Theoretical and experimental investigation of the aerodynamic drag due to automotive cooling systems
Authors: Barnard R. H.
Published: April 2011

Theoretical expressions for the aerodynamic drag due to the internal cooling flow in road vehicles are examined. The advantages of a ducted system and the sizing and location of inlet and outlet apertures are discussed. Experimental tests to evaluate theoretical relationships in model scale are described, and practical conclusions concerning drag minimization are drawn.
Modelling NOx emissions from spark-ignition engines
Authors: Sodré J. R.
Published: April 2011

A rapid chemical equilibrium composition model was applied to calculate the main combustion products from spark-ignition engines. The kinetic concentrations of oxides of nitrogen were evaluated on the basis of their equilibrium concentrations. To validate the model, experiments were carried out in a single-cylinder research engine. Results for CO, CO2, O2 and NOX emissions show good agreement between model and experiments for varied air-fuel ratio, speed, ignition timing, compression ratio and cylinder wall temperature.
Full-cycle firing simulation of a pent-roof spark-ignition engine with visualization of the flow structure, flame propagation and radiative heat flux
Authors: Henson J. C. , Malalasekera W
Published: April 2011

A numerical study is made of how the complex geometry of a pent-roof spark-ignition engine influences the flow field, the flame propagation and, novelly, the instantaneous radiative heat flux. The solver integrates a generalized weighted-sum-of-grey-gases-discrete transfer method radiation model into the computational fluid dynamics code KIVA-II also modified to enable the simulation of open ports and canted valves, wave action effects in the exhaust and mixing-controlled combustion.

The full-cycle mean pressure variation is in good agreement with measurements. The overall burning angle of 37° crank angle and peak radiative flux of 210 kW/m2 are also plausible on the basis of published data. Finally, remarkable insight is gained into how the head geometry and flow structure influence flame propagation and in turn how this governs the spatial and temporal variation in radiative heat flux on the cylinder walls.
Influence of performance characteristic of a gaseous fuel supply system on hydrocarbon emissions of a dual-fuel engine
Authors: Ren J , Wang Z. Y. , Zhong H , Hao S. H.
Published: April 2011

Abstract: The performance of the gaseous fuel supply and its influence on hydrocarbon (HC) emissions of dual-fuel engines have been investigated. A new design of manifold respirators with mixers is also presented in the paper. The design of the gaseous fuel supply system has a great influence on HC emissions in the dual-fuel engine at light load. The problem of scavenging is discussed and solved by using the manifold respirators in the dual-fuel engine. It performs the function of retarding the gaseous fuel entry timing from the moment of intake valve opening, and its delaying effects have been measured and tested. Experimental results show that the manifold respirator gives the best performance in reducing HC emissions compared with a common pipe mixer and a respirator with no mixer. In addition, the mixing effects are sensitive to the mixer configurations.
Throttle body: Modelling and identification
Authors: Cary M , Ebrahimi M , ffrench K , Sbaschnig R
Published: April 2011

Mathematical modelling of the throttle body air flow is one of the first steps in generating a generic spark ignition (SI) engine model for control-oriented development. Typically, the throttle body flow model is subdivided into components: a one-dimensional isentropic flow law, an empirically derived effective area component and a closed plate leakage term. Of these, only the effective area term presents any difficulty. This paper describes the mathematical formulation and analysis of a generic model for the throttle body. Once the model is formulated, the experimental procedure for the identification and estimation of the numerical values of the elements within the model is described. The primary focus of the analysis procedure is the statistical modelling methods associated with calibrating the effective area term. Non-linear repeated measurement analysis methods are used for this purpose.
Comparison of upper extremity test devices for the evaluation of frontal air bags
Authors: Bass C R , Duma S M , Crandall J R , George S , Kuppa S , Khaewpong N , Sun E , Eppinger R
Published: April 2011

This study examines the response of two upper extremity test devices under driver-side air bag deployment to contribute to the development of dummy surrogates for the investigation of primary contact forearm injuries during air bag deployments. The first of these test devices, the SAE 5th Percentile Female Arm (SAE arm), is an anthropomorphic representation of a small female forearm and upper arm that is instrumented with load cells, accelerometers and potentiometers to enable the determination of upper extremity kinematics and dynamics. The second, the Research Arm Injury Device (RAID), is a simple beam test device designed for detailed investigation of moments and accelerations resulting from close contact in the initial stages of air bag deployment. It includes strain gauges distributed along its length to measure the distribution of moment applied by the air bag deployment. The study used four air bags representing a wide range of aggressivities in the current automobile fleet. Logistic risk functions for forearm fracture were developed using existing cadaver studies and the moment response of each test device. These risk functions indicate that, for 50 per cent risk of ulna or ulna/radius fractures, the SAE arm peak forearm moment is 67 N m while the RAID peak forearm moment is 373 N m.
Robustness of powertrain mount system for noise, vibration and harshness at idle
Authors: Qatu M , Sirafi M , Johns F
Published: April 2011

Noise, vibration and harshness (NVH) has become an increasingly important attribute in vehicle engineering. At idle conditions, customer-perceived NVH is dominated by powertrain NVH. Powertrain NVH can be radiated engine noise or noise (and vibration) transmitted through the powertrain mounting system. This paper discusses the variability in the latter NVH as a function of the variability of the mount stiffness parameters. A simple six-degree-of-freedom model is used in the analysis. A detailed design of experiment studies was conducted. It is concluded that better control of mount stiffness parameters would result in improved prediction and performance of idle NVH.
Potential of electric wheel motors as new chassis actuators for vehicle manoeuvring
Authors: Jacobsen B
Published: April 2011

The stability and yaw control systems in today's vehicles are increasingly appreciated for active safety. They use individual wheel braking to obtain an extra yaw moment. Adding individual traction, e.g. through electric wheel motors, would increase the available extra yaw moment. The present work investigates the manoeuvrability potential of such a concept. A passenger car employing electric wheel motors at the rear axle is compared with the same vehicle using only brake intervention. The potential, or ultimate limits, are investigated for two driving situations. The time delay in yaw speed change when entering a curve is estimated. A reduction of some 10-30 per cent is found, the highest gains being at low longitudinal speed. For pure lateral translation, the maximum initial lateral acceleration is estimated and a 40 per cent increase is predicted. The investigation is based on mathematical analysis employing a modified version of the common bicycle model. The feasibility of introducing these solutions in series-produced vehicles is discussed briefly. Cost aspects are not considered in any great detail, but it is emphasized that such aspects must be weighed not only against improved manoeuvrability but also against reduced environmental impact and improved longitudinal driveability, all of which are attainable with electric propulsion.