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

Management of a Single-User Multi-Robot Teleoperated System for Maintenance in Offshore Plants

This chapter proposes a new approach to management method of a single-user multi-robot teleoperated system for maintenance in offshore plants. The management method is designed to perform a 1:N mode (here, “1” refers to the number of operators and “N” denotes the number of slave robots), in which a single operator teleoperates a number of slave robots directly to conduct a maintenance task, or in an autonomous cooperation mode between slave robots in order to overcome the limitations of the aforementioned 1:1 teleoperation mode. The aforementioned management method is responsible for the role sharing and integration of slave robots to divide the operation mode of the slave robots into various types according to the operator’s intervention level and the characteristics of the target maintenance task beforehand and to perform the target maintenance task using the robot operation mode selected by the operator

Electrochemical Behavior of SWCNT-TPLF Electrode Compared to SWCNT-coated GCE and GE Electrodes

Redox reaction [Fe(CN)6]3– / [Fe(CN)6]4– has been studied with a Single-Walled Carbon Nanotube (SWCNT)-coated Glassy Carbon Electrode (GCE), SWCNT-coated Gold Electrode (GE) and a lab-made SWCNT-TPLF (SWCNT-Thin-Paper-Like-Film) Electrode. The SWCNT-modified electrode has shown a well-defined redox peak compared to bare electrodes. Cyclic voltammetry was used in 50.0 × 10–3 M aqueous solution of KCl containing K4[Fe(CN)6] to obtain information on both the capacitive background and electron transfer from the faradaic reaction of the redox species. The capacitance gives insight into the effective surface area (including both the exterior and interior surfaces within the coated and TPLF electrodes) as well as the pseudocapacitance due to faradaic reactions of surface bonded oxides. Among the three types of electrodes, the SWCNT-TPLF electrode showed the largest volume specific capacitance, consistent with its highest carbon nanotube packing density and largest effective surface area. This indicates that the carbon nanotube working electrode (whether coated or film electrode) behaves as a three-dimensional electrode. The redox reaction of [Fe(CN)6]3– / [Fe(CN)6]4– was found to occur not only at the outer surface of the carbon nanotube but also at the interior surface of the thin paper like nanotube electrode

A New Ultra-lightweight RFID Authentication Protocol using Merge and Separation Operations

Abstract Since Low-cost RFID tags have very limited hardware resources, it is difficult to implement an authentication protocol which uses heavy operations such as modern ciphers or hash functions. It has been presented some ultra-lightweight RFID authentication protocols for low-cost RFID tags by using very light operations. Recently, Jeon and Yoon proposed a new ultra-lightweight RFID authentication protocol. They defined and used the merge and separation operations. The merge operation can merge the bits from two bit strings and the separation operation is an inverse operation of the merge operation. However, we found that the protocol cannot serve correctly when the collision of tag pseudonyms is occurred. In this paper, we propose an improved authentication protocol that solves the problem. We show that the proposed protocol can resist various security attacks and is efficient enough to implement low-cost RFID tags

有機無機薄膜太陽電池における新規電荷選択及び輸送界面の研究

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 長谷川 哲也, 東京大学教授 斉木 幸一朗, 東京大学教授 森 初果, 東京大学准教授 狩野 直和, 東京大学教授 小澤 岳昌University of Tokyo(東京大学

Development of Micro/Nano-Scale Sensors for Investigation of Heat Transfer in Multi-Phase Flows

The objective of this investigation was to develop micro/nano-scale temperature sensors for measuring surface temperature transients in multi-phase flows and heat transfer. Surface temperature fluctuations were measured on substrates exposed to phase change processes. Prior reports in the literature indicate that these miniature scale surface temperature fluctuations can result in 60-90 percent of the total heat flux during phase change heat transfer. In this study, DTS (Diode Temperature Sensors) were fabricated with a doping depth of ~100 nm on n-type silicon to measure the surface temperature transients on a substrate exposed to droplet impingement cooling. DTS are expected to have better sensor characteristics compared to TFTs (Thin Film Thermocouples), due to their small size and faster response (which comes at the expense of the smaller operating temperature range). Additional advantages of DTS include the availability of robust commercial micro fabrication processes (with diode and transistor node sizes currently in the size range of ~ 30 nm), and that only 2N wire leads can be used to interrogate a set of N x N array of sensors (in contrast thermocouples require 2 N x N wire leads for N x N sensor array). The DTS array was fabricated using conventional semi-conductor processes. The temperature response of the TFT and DTS was also calibrated using NIST standards. Transient temperature response of the DTS was recorded using droplet impingement cooling experiments. The droplet impingement cooling experiments were performed for two different test fluids (acetone and ethanol). An infrared camera was used to verify the surface temperature of the substrate and compare these measurements with the temperature values recorded by individual DTS. PVD (Physical Vapor Deposition) was used for obtaining the catalyst coatings for subsequent CNT synthesis using CVD (Chemical Vapor Deposition) as well as for fabricating the thin film thermocouple (TFT) arrays using the "lift-off" process. Flow boiling experiments were conducted for three different substrates. Flow boiling experiments on bare silicon wafer surface were treated as the control experiment, and the results were compared with that of CNT (Carbon Nano-Tube) coated silicon wafer surfaces. Similar experiments were also performed on a pure copper surface. In addition, experiments were performed using compact condensers. Micro-scale patterns fabricated on the refrigerant side of the compact heat exchanger were observed to cause significant enhancement of the condensation heat transfer coefficient