A quantitative analysis of a trace amount of hydrogen in high temperature heat-treated carbons

A technique to determine a trace amount of hydrogen in carbon materials heat-treated above 1000 °C was developed. Three types of carbons prepared from poly(furfulyl alcohol), poly(vinyl chloride) and mesophase carbon microbeads were heat-treated at various temperatures ranging from 1000 to 1800 °C. Then they were gasified by O₂ in a fixed bed flow reactor, and the H₂O gases formed during the gasification processes were carefully monitored with a Karl Fischer moisture analyzer. As a result, this method makes it possible to determine the hydrogen contents in the carbons down to three places of decimals as a weight percent and can detect even a trace amount of hydrogen as low as 0.002 wt.%. A possible chemical structure of carbon edge sites was also discussed based on the experimentally determined hydrogen contents.     

A Thermo-Elastic Analysis of the Parallel Surface Thrust Washer

An optical interference method was used to display the distorted film shape in nominally parallel surface thrust washers. The bearings were made of aluminium to accentuate thermal expansion and were carefully lapped flat before use. Both the experimental results and an analysis of the coupled elasticity, Reynolds and energy equations confirm that these bearings operate by the formation of a slightly converging film over the leading 80 percent (or less) of the pad. Fair agreement was obtained between the analysis and previously developed multiple regression equations. Thrust washers for industrial use with random waviness are likely lo perform better than lapped bearings.     

Behavior of insoluble materials in artificial contamination tests

It was reported that the dc flashover voltage under an artificial contamination test sometimes was affected considerably by the type of insoluble materials in the contaminant. To clarify the cause of this phenomenon, the physical characteristics of some contamination slurries and the conductivity of the artificially contaminated insulator surfaces are investigated experimentally. The test results lead to the conclusion that the variation in the flashover voltage is caused mainly by the characteristics of conductive films formed on the insulator surface in the clean fog test     

Tandem MIG welding of aluminium alloys

Welding processes used in transport system manufacturing, such as the automotive industry, have in recent years seen a pronounced trend towards fabrication of lower-cost welded structures through efficiency enhancement focused on weld quality improvement. In this context, arc welding processes providing sufficient weld reinforcing ability, while allowing higher-speed welding are expected to emerge. In welding of aluminium alloys, MIG welding conferring superior economy and profitability holds out particularly high expectations, in future set to be the mainstream process for fabrication of welded structures. In MIG welding, however, straightforward adoption of higher welding speeds for efficiency enhancement purposes leads to loss of joint quality and weldpool turbulence due to increased current. Welding speeds therefore normally have an upper limit of around 1.5 m/min.¹ More recently, however, further welding speed increases have been sought through improvement of wire feed¹ and power supply² systems.     

Transient elastodynamic boundary element formulations based on the time-stepping scheme

A new method is presented in this paper to analyze transient elastodynamic problems with damping by the boundary element method formulated in terms of the fundamental solution for steady elastodynamics after approximating acceleration and velocity components by finite difference or implicit time integration schemes such as the Newmark method and the Wilson θ method. The effects of the approximation scheme and time step on accuracy are examined through numerical examples for one-dimensional transient response.     

Individual Traffic Characteristics Queueing Systems with Multiple Poisson and Overflow Inputs

A theoretical method for analyzing overflow problems in queueing systems is presented. An interrupted Poisson process (IPP) approximation of overflow traffic is employed. An overflow stream is replaced by an IPP using the three-moment matching method. For a three-input model, to which one Poisson and two IPP streams are offered simultaneously, explicit and iterative formulas are derived to calculate the mean waiting time, overflow probability, and moments of overflow traffic intensity from the system for each of the three input streams. This three-input model is a general one, and can be used for analyzing complex problems such as multistage overflow models and individual traffic characteristics for a model with more than three inputs. By setting the capacity of the waiting room of the three-input model to 0, this method can cover loss systems. For both queueing and loss systems, several numerical examples of typical traffic models are shown. Comparisons are made between theoretical values and experimental values by computer simulations, and it is demonstrated that the accuracy of the method is excellent.     

A High-Speed Optical Data Highway for Industrial Control Systems

Recent application of distributed control systems to large-and medium-scale industrial plants requires effective and high-speed communication among the control devices each other to ensure high-performance operation.     

New Ink Jet Recording for Generating a Plurality of Ink Jet Streams

A new solid-state scanning ink jet recording technique, called slit jet recording, is proposed. This technique uses a recording head with one slitlike ink-issuing opening having a number of recording electrodes arrayed along a horizontal scanning direction. The ink is emitted from the ink-issuing opening due to the electrical potential difference between a driven recording electrode and a counterelectrode located behind the recording paper. The ink strikes the paper and forms a recording dot. Many recording electrodes can be driven simultaneously by video signals which enhance the total copy recording speed over that for conventional techniques using a single nozzle. The head of this ink jet recording apparatus is remarkably simple in construction and can be fabricated without difficulty. Improvements in reliability and maintainability can also be expected, as the simple structure of the ink-issuing opening reduces clogging and facilitates easy cleaning as compared with other equipment having a large number of nozzles. The recording principle and characteristics and ink-issuing characteristics are described, and the results of a trial recording are presented. The results show that an ISO A4 size (210 mm x 297 mm) full-color copy can be recorded in about 30 s at an 8-dot/ mm rate.