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

The value of social search: Seeking collective personal experience in social Q&A

In this paper, we examine the value of social question‐answering (Q&A) services as a platform for social search. We present a quasi‐field study where we instructed 20 study participants to use a social Q&A service, Yahoo! Answers, for a period of one week, and interviewed them about their experience with Yahoo! Answers based on the questions (N=99) they posted to the site. The results indicate that participants turned to a social search system when they needed firsthand information, diverse perspectives, and others' value judgments. Participants also preferred social search systems over web search engines in situations where they could obtain tailored information, access original and non‐popular information, filter out information, and interact with real people. Various strategies that participants employed to ensure that their questions would be likely to be answered were also identified. This study contributes to the field of information science by investigating a social Q&A service using the framework of social search from the information seeker's perspective. The results have implications for developers and designers of social search systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106937/1/14505001067_ftp.pd

State Estimation Based on Kinematic Models Considering Characteristics of Sensors

Abstract-The major benefit of the state estimation based on kinematic model such as the kinematic Kalman filter (KKF) is that it is immune to parameter variations and unknown disturbances and thus can provide an accurate and robust state estimation regardless of the operating condition. Since it suggests to use a combination of low cost sensors rather than a single costly sensor, the specific characteristics of each sensor may have a major effect on the performance of the state estimator. As an illustrative example, this paper considers the simplest form of the KKF, i.e., the velocity estimation combining the encoder with the accelerometer and addresses two major issues that arise in its implementation: the limited bandwidth of the accelerometer and the deterministic feature (non-whiteness) of the quantization noise of the encoder at slow speeds. It has been shown that each of these characteristics can degrade the performance of the state estimation at different regimes of the operation range. A simple method to use the variable Kalman filter gain has been suggested to alleviate these problems using the simplified parameterization of the Kalman filter gain matrix. Experimental results are presented to illustrate the main issues and also to validate the effectiveness of the proposed scheme

Cooperative Least Square Parameter Identification by Consensus within the Network of Autonomous Vehicles

authors' post-printIn this paper, a consensus framework for cooperative parameter estimation within the vehicular network is presented. It is assumed that each vehicle is equipped with a dedicated short range communication (DSRC) device and connected to other vehicles. The improvement achieved by the consensus for parameter estimation in presence of sensor’s noise is studied, and the effects of network nodes and edges on the consensus performance is discussed. Finally, the simulation results of the introduced cooperative estimation algorithm for estimation of the unknown parameter of road condition is presented. It is shown that due to the faster dynamic of network communication, single agents’ estimation converges to the least square approximation of the unknown parameter properly.Natural Sciences and Engineering Research Council || CRDPJ/431233-12 Nuvation Engineering, Waterloo, ON, Canad

An Examination of A.W. Tozer\u27s Life as Practical Applications for Korean Pastors to Combat the Prosperity Gospel

In recent years, more Korean pastors are preaching the prosperity gospel in order to pursue quantitative church growth and seem uninterested in companionship with God. However, faithful men, like Aiden Wilson Tozer, always preached the gospel of the Cross alongside an intimate relationship with God. His life and ministry are examples of a true pastor called by God. Like Tozer, pastors in South Korea must discipline themselves to walk with God. The purpose of this thesis is to provide Korean pastors with practical applications for combating the prosperity gospel by building intimate companionship with God in their ministries by examining Tozer\u27s life, writings, and sermons. The survey related to Korean pastors\u27 ministry and spiritual lives will be used to study and develop practical applications for intimacy with God. This study will help Korean pastors to combat the prosperity gospel and build an intimate relationship with God

Spatiotemporal Stochastic Resonance in Fully Frustrated Josephson Ladders

We consider a Josephson-junction ladder in an external magnetic field with half flux quantum per plaquette. When driven by external currents, periodic in time and staggered in space, such a fully frustrated system is found to display spatiotemporal stochastic resonance under the influence of thermal noise. Such resonance behavior is investigated both numerically and analytically, which reveals significant effects of anisotropy and yields rich physics.Comment: 8 pages in two columns, 8 figures, to appear in Phys. Rev.

Human Brain Astrocytes Mediate TRAIL-mediated Apoptosis after Treatment with IFN-γ

TNF-related apoptosis inducing ligand (TRAIL) expressions were studied in primary human brain astrocytes in response to pro-inflammatory cytokines. When astrocytes were treated with IL-1β, TNF-α or IFN-γ, TRAIL was induced in cultured fetal astrocytes. In particular, IFN-γ induced the highest levels of TRAIL in cultured astrocytes. When astrocytes were prereated with IFN-γ, they induced apoptosis in TRAIL-sensitive Peer cells. Our results suggest that IFN-γ modulates the expression of TRAIL in astrocytes, which may enhance cytotoxic sensitivity of infiltrating immune cells or brain cells other than astrocytes during inflammation of brain