Application of an adaptive tuned vibration absorber on a dual lay-shaft dual clutch transmission powertrain for vibration reduction

© 2018 Elsevier Ltd This paper investigates the application of adaptive tuned vibration absorbers (ATVAs) to lightly damped automotive powertrains. To achieve this, a vibration characteristic analysis of a dual lay-shaft dual clutch transmission (DCT)-equipped powertrain system was performed, including a natural frequency evaluation and sensitivity studies. Transient responses due to gear changes and variations of both the gear ratio and engine speed were also evaluated. The results demonstrate that the impact of ATVAs on transient responses during gear changes is minimal, suggesting that these short-duration transients are outside the scope of application for ATVAs. However, as excitation forces originate from the engine, speed has a significant impact on excitation frequency. Furthermore, the gear ratios significantly influence the engine operating range and natural frequency in any particular gear. Therefore, variations of engine speeds and gear ratios are the main influencing factors affecting the dominant excitation frequency. Consequently, the relationships among the system natural frequencies, the dominant external excitation frequency and the inherent frequency of the ATVA are comprehensively studied. By investigating the relationships among the dominant external excitation frequency and system natural frequencies and the system sensitivity analysis results, the installation position, stiffness range and optimal frequency tuning scheme of the ATVA can be determined. The results were applied to a DCT powertrain with continuously changing engine speeds and an ATVA with corresponding variable stiffness, and a frequency tuning scheme is installed on the powertrain. By comparing the simulation results, the effectiveness and reliability of the presented method can be verified

Improving efficiency in drive lines : an experimental study on churning losses in hypoid axle

The research concerns improvement of the power efficiency of lubricated components in automotive drivelines such as transmissions and axles. Meshed gear pairs, rolling bearings, seals and oil churning by rotating components immersed in the oil are studied. The purpose of the research is to explore the most effective way of improving the efficiency in drivelines, focusing on an axle comprising hypoid gears and a differential assembly. First, a study of the nature of losses affecting the efficiency of a simple spur gear box was carried out, and a model of friction and churning in a simple transmission was developed. Next, a detailed experimental study of oil churning losses in a hypoid axle from a four wheel drive road vehicle was carried out using the inertia run-down technique. To perform the above experiments, a new test rig for measuring oil churning losses was designed, manufactured and commissioned. The test rig allowed a wide range of speed and lubricant parameters to be explored and was designed by the author for tests available at different roll and pitch attitudes. In addition, an "extended" housing, consisting of a modified gear case that accepted the same internal components as the production axle but which had much greater internal clearances, was designed and manufactured. This enabled the effects of different casing geometry and of internal baffles to be studied. Additionally, the extension housing was modified to investigate the oil flow inside the housing through its one transparent side for the understanding of the effect of oil flow on churning losses. An investigation of design-related parameters influencing churning losses was carried out using the new test rig. Empirical equations for the churning losses, based on dimensional analysis, were developed to describe the test results. It was found that some combinations of baffles gave a significant reduction in losses. Supplementary tests were carried out using transparent windows to visualise the oil flow. These identified some of the mechanisms responsible for the reduction in churning loss and suggested a number of practical methods by which churning could be reduced without compromising the lubricant supply to remote components. It is argued that these innovations can contribute to improving fuel efficiency and limiting oil temperature rise in all-wheel-drive vehicles

Accuracy modeling and analysis for a lock-or-release mechanism of the Chinese Space Station Microgravity Platform

With development of Chinese space science and technology, plenty of microgravity experiments will be conducted in the Chinese Space Station to be built, and therefore demand for high-precision electromechanical equipment increases substantially. In this paper, a comprehensive accuracy analysis of a new type of auto lock-or-release (L/R) mechanism, which is applied in the Space Station Microgravity Platform (SSMP), is implemented. Firstly, two models (vector analysis model and vector differential model) are, therefore, proposed to analyze output errors of the mechanism. Due to transmission errors from the transmission chain of the gear mechanism, influence factors on axial errors of lead screws are analyzed using design of experiment (DOE) for factor sensitivities. It shows that manufacturing tolerances of the lead screw is the dominant factor. Then, verification of the two proposed accuracy models is comparatively implemented through Monte Carlo (MC) simulation and DOE. Using the present accuracy model, location errors of the lead screw throughout the mechanism's working stroke are illustrated, where the non-synchronous error of the mechanism is particularly discussed. A linear relation between the variance of the non-synchronous error and that of the structural error is established, followed by analyzing influence factors on the non-synchronous error

An analysis of sustainability issues in eastern Indonesian pole-and-line tuna fisheries

PhD ThesisSustaining healthy tuna fisheries is crucial to Indonesia‘s national income from the fisheries sector and to securing the fishers‘ livelihoods. Yet sustainability issues in the small-scale pole-and-line tuna fisheries have been little analysed, and this study helps to fill some gaps in the literature. Data were collected from ten sites across eastern Indonesia (Sorong, Ternate, Pulau Bacan, Larantuka, Kupang, Bali, Surabaya, Bandung, Bogor and Jakarta) by four methods: review of academic and other publications; quantitative questionnaire surveys; qualitative interviews with key informants; and personal observations. The thesis investigates potential short-term effects of a government moratorium on foreign fishing vessel on small-scale tuna pole-and-line fishing (Chapter 2); trends in landings and effort (Chapter 3); the relationships between fishing effort and oceanographic variables at fish aggregating devices (FADs) sites (Chapter 4); and market supply strategies (Chapter 5). The findings of the study are: (1) the moratorium had little effect on the tuna poleand-line fishery, yet fishers claimed it helped them to fish more freely. (2) Landings trends varied between locations but in general from 2012 the landings volumes declined. (3) Stakeholders perceived that the government‘s published fisheries data were inaccurate because they were not collected using established scientific principles. (4) There were positive relationships between catch per unit of effort (CPUE) and both sea surface temperature (SST) and chlorophyll-a (chl-a) concentration but these were relatively weak. (5) On market supply, only Sorong seemed to demonstrate the initiative to access export markets by partnering with international private companies and preparing for Marine Stewardship Council (MSC) certification, an essential strategy if the fisheries are to achieve their full potential in the global tuna market. Tuna pole-and-line fisheries in eastern Indonesia are in moderately good shape, but they face significant challenges including diminishing tuna stocks, illegal, unreported and unregulated fishing practices; competition from industrial vessels, and restricted marketing options.Indonesian Government through the Directorate General of Research and Higher Education Resources, the Ministry of Research and Higher Education (formerly the Ministry of Education and Culture

Mechanical Engineering

The book substantially offers the latest progresses about the important topics of the "Mechanical Engineering" to readers. It includes twenty-eight excellent studies prepared using state-of-art methodologies by professional researchers from different countries. The sections in the book comprise of the following titles: power transmission system, manufacturing processes and system analysis, thermo-fluid systems, simulations and computer applications, and new approaches in mechanical engineering education and organization systems

NASA Tech Briefs, November 2010

Topics covered include: Portable Handheld Optical Window Inspection Device; Salience Assignment for Multiple-Instance Data and Its Application to Crop Yield Prediction; Speech Acquisition and Automatic Speech Recognition for Integrated Spacesuit Audio Systems ; Predicting Long-Range Traversability from Short-Range Stereo-Derived Geometry; Browser-Based Application for Telemetry Monitoring of Robotic Assets; Miniature Low-Noise G-Band I-Q Receiver; Methods of Using a Magnetic Field Response Sensor Within Closed, Electrically Conductive Containers; Differential Resonant Ring YIG Tuned Oscillator; Microfabricated Segmented-Involute-Foil Regenerator for Stirling Engines; Reducing Seal Adhesion in Low Impact Docking Systems; Optimal Flow Control Design; Corrosion-Resistant Container for Molten-Material Processing; Reusable Hot-Wire Cable Cutter; Deployment of a Curved Truss; High-Volume Airborne Fluids Handling Technologies to Fight Wildfires; Modeling of Alkane Oxidation Using Constituents and Species; Fabrication of Lanthanum Telluride 14-1-11 Zintl High-Temperature Thermoelectric Couple; A Computer Model for Analyzing Volatile Removal Assembly; Analysis of Nozzle Jet Plume Effects on Sonic Boom Signature; Optical Sidebands Multiplier; Single Spatial-Mode Room-Temperature-Operated 3.0 to 3.4 micrometer Diode Lasers; Self-Nulling Beam Combiner Using No External Phase Inverter; Portable Dew Point Mass Spectrometry System for Real-Time Gas and Moisture Analysis; Maximum Likelihood Time-of-Arrival Estimation of Optical Pulses via Photon-Counting Photodetectors; Handheld White Light Interferometer for Measuring Defect Depth in Windows; Decomposition Algorithm for Global Reachability on a Time-Varying Graph; Autonomous GN and C for Spacecraft Exploration of Comets and Asteroids; Efficient Web Services Policy Combination; Using CTX Image Features to Predict HiRISE-Equivalent Rock Density; Isolation of the Paenibacillus phoenicis, a Spore-Forming Bacterium; Monolithically Integrated, Mechanically Resilient Carbon-Based Probes for Scanning Probe Microscopy; Cell Radiation Experiment System; Process to Produce Iron Nanoparticle Lunar Dust Simulant Composite; Inversion Method for Early Detection of ARES-1 Case Breach Failure; Use of ILTV Control Laws for LaNCETS Flight Research;and Evaluating Descent and Ascent Trajectories Near Non-Spherical Bodies

The application of time encoded signals to automated machine condition classification using neural networks

This thesis considers the classification of physical states in a simplified gearbox using acoustical data and simple time domain signal shape characterisation techniques allied to a basic feedforward multi-layer perceptron neural network. A novel extension to the signal coding scheme (TES), involving the application of energy based shape descriptors, was developed. This sought specifically to improve the techniques suitability to the identification of mechanical states and was evaluated against the more traditional minima based TES descriptors. The application of learning based identification techniques offers potential advantages over more traditional programmed techniques both in terms of greater noise immunity and in the reduced requirement for highly skilled operators. The practical advantages accrued by using these networks are studied together with some of the problems associated in their use within safety critical monitoring systems.Practical trials were used as a means of developing the TES conversion mechanism and were used to evaluate the requirements of the neural networks being used to classify the data. These assessed the effects upon performance of the acquisition and digital signal processing phases as well as the subsequent training requirements of networks used for accurate condition classification. Both random data selection and more operator intensive performance based selection processes were evaluated for training. Some rudimentary studies were performed on the internal architectural configuration of the neural networks in order to quantify its influence on the classification process, specifically its effect upon fault resolution enhancement.The techniques have proved to be successful in separating several unique physical states without the necessity for complex state definitions to be identified in advance. Both the computational demands and the practical constraints arising from the use of these techniques fall within the bounds of a realisable system