An integrated dialect analysis tool using phonetics and acoustics

This study aimed to verify a computational phonetic and acoustic analysis tool created in the MATLAB environment. A dataset was obtained containing 3 broad American dialects (Northern, Western and New England) from the TIMIT database using words that also appeared in the Swadesh list. Each dialect consisted of 20 speakers uttering 10 sentences. Verification using phonetic comparisons between dialects was made by calculating the Levenshtein distance in Gabmap and the proposed software tool. Agreement between the linguistic distances using each analysis method was found. Each tool showed increasing linguistic distance as a function of increasing geographic distance, in a similar shape to Seguy's curve. The proposed tool was then further developed to include acoustic characterisation capability of inter dialect dynamics. Significant variation between dialects was found for the pitch, trajectory length and spectral rate of change for 7 of the phonetic vowels investigated. Analysis of the vowel area using the 4 corner vowels indicated that for male speakers, geographically closer dialects have smaller variations in vowel space area than those further apart. The female utterances did not show a similar pattern of linguistic distance likely due to the lack of one corner vowel /u/, making the vowel space a triangle

Effect of bearing thermally induced preload on the efficiency of automotive manual transmission under RDE

In order to calculate the efficiency of an automotive manual transmission, taking into consideration the effect of its most power consuming components - gears and bearings - as well as the interactions between them, is of high importance. In this paper, a dynamic model has been developed which can predict the frictional losses of a complete gearbox as a system and, thus, its efficiency. The effect of temperature on bearing preload is also considered and taken into account from a system perspective identifying its effect on the bearings frictional losses (as well as the overall efficiency). The operating conditions used are snapshots of the RDE (Real Driving Emissions) driving cycle, which is a standard metric for automotive manufactures. Results show that doubling the temperature can lead to 120% increase of the bearing losses and up to 140% increase of the total transmission losses. The effect of the variation of operating conditions (velocity and torque) is also taken into account.The novelty of this paper lays in the development of a dynamic model which takes into account the performance of a complete gearbox under transient operating conditions, as well as the interaction among its main components and the ability to make changes on the influencing factors of transmission efficiency so that their effect on the complete gearbox efficiency can be tracked. This has not been yet reported in the relevant literature which mainly focuses on the influencing factors of transmission power loss and efficiency experimental measurements under various operating conditions for gear pairs instead of complete gearboxes.</div

A system level computational model for thermo-tribological functioning of high-performance racing transmission with dry sump lubrication

Dry sump lubrication is a key feature in transmission systems of high-performance racing applications. While it provides adequate oil for gears contact, it reduces churning losses. Moreover, provision of continuous oil for gear contacts in harsh conditions during a race, makes dry sump lubrication systems more reliable. One of the most important aspects of any dry sump system is the assessment of its thermo-tribological performance and its capability to remove the generated heat from highly loaded high shear gear contacts. In this paper, a multiphysics integrated numerical method of a dry sump transmission, considering a system approach is presented. The method provides a validated predictive tool to assess thermal functioning of dry sump lubrication systems

Coupled tribo-dynamic modelling of linear guideways for high precision machining application

Linear guideways play a crucial role in determining precision of machine tools. Understanding their dynamic response is essential for objectively controlling their behavior and performance in operation. Due to highly loaded lubricated contacts, mixed-elastohydrodynamic regime is dominant. The mixed-elastohydrodynamic film maintains the coupling between horizontal degree of freedom (feed velocity) and vertical degree of freedom (loading direction). This paper presents a novel tribo-dynamic solution for linear guideways, taking in to account the lubricant effects and coupling between horizontal and vertical degrees of freedom. An analytical tribology model is used implicitly within the dynamic model. For in-depth tribological quantities including pressure and film thickness distribution, an explicit full numerical solution for mixed-elastohydrodynamic is utilized. Results show that the coupled solution of vertical and horizontal degrees of freedom taking in to account lubricated contacts is essential. It is shown that at moderate and light loads, the effect of this coupling and presence of lubricant is more pronounced

Effect of multi-speed transmission design on the drive cycle performance of a series-parallel hybrid electric vehicle

For the passenger car sector, original equipment manufacturers (OEMs) homologation activities towards meeting emission legislation standards (set by regulation EC No. 443/2009) have compelled the design of greener transport. The dominant emerging trend of major OEMs has been to produce a hybridised powertrain solution to reduce their overall fleet CO2 targets. Hybrid electric vehicles allow manufacturers to use already available powertrain sub-systems to reduce development cost. Simulation in the design process has now been firmly adopted to reduce the number of prototypes required in the automotive sector as a means of reducing cost. In this study, a quasi-static drive cycle analysis of a multi-speed series-parallel hybrid has been undertaken to demonstrate the drivetrain’s capability to reduce fuel consumption. This configuration maintains the main drivetrain multi-speed design to further optimise fuel economy over the NEDC, and WLTC. Results for WLTC indicated that this optimum hybridised system can improve fuel economy in comparison to the internal combustion engine (ICE) only system by up to 22.1

Effect of lubricant starvation on the tribo-dynamic behavior of linear roller guideway

This paper presents an experimentally validated numerical approach linear roller guideways considering coupled vertical and horizontal (feed) motions and taking into account lubricant starvation. The inlet starvation is considered by incorporating potential flow method. Results show that starvation has pronounced effect on the lubricant film thickness, friction and applied load on contact by up to 32%. Localised pressure values may vary by up to 100%. The severity of starvation effect is frequency dependent. It is also revealed that the starvation effect can be controlled by the amount of preload on linear guideway

Editors’ perspectives: synergistic technologies for dedicated hybrid powertrains

Regulatory and market pressure to reduce greenhouse gas (GHG) emissions has directed the path of powertrain development towards expanded use of electrification. Powertrain electrification contributes to GHG reduction by lowering the demands on the engine for improved durability and efficiency and by introducing synergistic technologies such as kinetic energy recovery. This work reviews the advancement of energy-efficient hybrid powertrains with application of dual motive powers, internal combustion engine and electric motors. The focus of this review is on the industrialisation of dedicated hybrid engines (DHEs) and transmissions (DHT). Based on the DHT framework, DHEs are exemplified through those successful hybrid vehicles in the market. Technology challenges for both DHE and DHT are discussed. The key enablers of controls and model-based design are reviewed to disclose the progress of hybrid powertrain development by using both endogenous fuel and exogenous electricity if applicable. Case studies for both passenger cars and commercial vehicles are also presented

Analytical multiphysics model for NVH prediction of a high-speed Surface-Permanent Magnet Synchronous Machine

As demands for electric motor efficiency keep increasing, Electric Vehicle (EV) manufacturers are striving to design smaller and more power-dense machines, able to maintain performance standards through high-speed operation. However, increased operating loads and speeds in excess of 10,000 rev/min results in the amplification, or introduction of new noise components, which necessitate novel prediction techniques. The use of traditional finite element (FE) based optimisation methodologies therefore becomes challenging due to extensive computational loads. In this work, an analytical multi-physics methodology for e-NVH prediction of typical high-speed Surface-mounted Permanent Magnet Synchronous Machines (S-PMSMs) is presented. The model comprises analytical electromagnetics and vibro-acoustics to determine the radiated airborne noise of SPMSMs at speeds above 10,000 rev/min and correspondingly high frequencies. Preliminary results are presented to highlight the efficiency of the proposed method.</p

Fuel consumption and emission reduction by using a CVT in series with conventional multi-speed transmission

Fuel economy is a growing concern for both manufacturers within the automotive sector and consumers. Increasing government legislation is driving towards greener vehicles with reduced CO2 and NOx emissions and greater fuel economy, especially within urban environments. Manufacturers use new technologies in their powertrain systems to tackle these problems. This paper simulates and evaluates the performance of using a half toroidal CVT in series with a conventional multi-speed transmission, by analysing different shifting strategies to optimise fuel consumption and NOx emissions over the NEDC using this novel approach. The results show an 8.83% increase in fuel economy and up to an 11.34% reduction in NOx emissions is possible using this arrangement. The introduction of CVT adds a further 1.18% increase in fuel economy and 3.59% decrease in NOx emissions. The paper concludes that this novel arrangement should be considered by automotive manufacturers as a solution for improvements to powertrain technology

Effects of transmission shaft flexibility on rolling element bearing tribodynamics in a high-performance transmission

In a high-performance transmission, rolling bearings play a crucial role in supporting the loaded shafts and gear mesh whilst minimising friction. Prediction of critical speeds and dynamic responses is important to avoid prolonged periods of elevated vibration amplitudes, which can contribute to premature bearing and gearbox failure. Nonlinearities such as backlash and time-varying stiffnesses can lead to complex coupled dynamics between gears and bearings. In the current study, an 8-speed transmission is discretized and modelled by the finite element method. The eigenproblem is solved using damped modal analysis considering gyroscopic effects. Time-varying stiffness data and backlashes are introduced as nonlinearities. The system response is compared for cases of linear and nonlinear bearings, and rigid and flexible shafts to ascertain the significance of elasticity. The flexible model improves the accuracy of bearing load oscillation by altering the transfer path between gears and bearings. This provides an advancement upon existing works, where shaft dynamics are often simplified. Furthermore, it is shown that the combination of local nonlinear effects and flexible components significantly changes the response of the system and the bearing life prediction for a system-level analysis