Earthquake prediction by the MT-system was proposed by Genichi Taguchi in 1995. Studies started in the Yano laboratory at Tokyo Denki University in 2004 demonstrated that earthquake prediction was possible to some extent, but there was considerable prediction error. A new study was started in line with new developments in the MT-system. Data collection was started in Tsukuba district. This paper gives a periodic analysis of seismic waveforms in the Tsukuba district and obtains the distances of ground vibrations by using the RT method, with the variance of the period as an attribute. The possibility of prediction by a further two-tail T method is shown, based on the variation of the distance over time. The estimated S/N ratio was -0.176 db and the sensitivity was 0.016 db. The prediction error was ±10% at a vibration velocity of 20μm/s.
Thin cylindrical parts in an automatic transmission (AT) are manufactured by plastic forming processes such as stamping. Especially, for the spline shape of a clutch drum, spline cold-rolling is adopted at Mazda for high dimensional accuracy. The ideal spline cold-rolling process was defined as one that could form all product shapes with high accuracy and efficiency. To optimize the process,quality engineering was used to carry out parameter design on the basis of energy evaluation, which is an innovative approach in the plastic forming field. A spline cold-rolling method was developed that improved quality and also improved the feed rate of the process by a factor of five. In addition, development time was greatly shortened, This paper describes the development Process.
A simple method of lead analysis is spectrophotometry, which makes use of absorption changes that occur when lead forms complexes with porphyrin in an aqueous solution. Actual sample solutions, however, contain unknown amounts of various components that affect the calibration curve. An attempt was made to alleviate this interference by the use of masking agents that bind to the interfering components. A measuring reagent containing several masking agents in addition to porphyrin was prepared and reacted with a lead solution to create a calibration curve, in which concentration of the masking agent solution was used as a control factor, concentration of lead in the sample solution was used as a signal factor, and the presence or absence of interfering substances in samples was used as noise factors N1 and N2. The levels of the control factors that maximized the S/N ratio were taken as the optimal conditions, and a confirmatory test was carried out. The gain was 4.1 db, which was 2.1 db larger than the estimated value. Although the reproducibility of the gain was poor, an improvement effect was observed. A simple detection method that can detect traces of lead without being affected by interfering components was developed (detection limit: 36μg/L).
Friction and abrasion problems are critical in mechanical systems because they greatly affect the length of the system's life. In this study, electric power versus load functionality in a sliding simulator was evaluated by use of the Amontons-Coulomb law, but the gain of the S/N ratio was not reproducible. The function of the simulator was then reconsidered and a new evaluation was performed. Since what the simulator does is to transport objects, the relation between transport distance and electric power was used as the evaluated function. As a result, the gain of the S/N ratio became reproducible, and the lubrication conditions for smooth movement of the simulator were optimized.
The purpose of this study was to reduce the tuning time of the transmission shift feeling of an off-road dump truck. Recently, the clutch engagement timing of most off-road trucks is electronically controlled according to the acceleration of the engine or driving conditions to obtain a more comfortable shift feeling. In the tuning of an actual vehicle, however, it takes a long time to filld the optimum control parameters for the clutch pressure. In this study, parameter design was used to find optimum parameters that would give a good shift feeling consistently and with high robustness. The calculations in this study were carried out by a combination of in-house dynamic simulation software and iSIGHT. It was confirmed that the tuning time of an actual vehicle could be reduced to half the current tuning time with the optimum parameters obtained as a result of this parameter design study.
A sensor manufacturer's decision to change the sensors used for sensing the brightness of medical monitors has raised the issue of evaluation of brightness sensors. In the past, they have been evaluated by accuracy tests and field tests,but in the accuracy tests there have been problems of measuring equipment calibration and measurement error, and the criteria (e.g. pass/fail) by which operation is evaluated in field tests have been ambiguous. Another problem has been the lack of a method of determining the comprehensive relative merits of brightness sensors. In this study, measurement error was evaluated according to the JIS Z 9090 standard, which provides an absolute quantitative scale for determining measurement error. That made it possible to quantify the effects of error factors, thereby enabling the comprehensive relative merits of brightness sensors to be evaluated. It is expected that quantified error factor effects will be taken into consideration in future development work. This study also suggests the possibility of quantitative evaluation of other similar products.
For more than five decades, the Taguchi System of Quality Engineering (TSQE) has been applied around the world in the areas of new product development,process improvement, product design, and services improvement. This research applies TSQE to develop an optimal strategy to build investment portfolios. This paper begins with an outline of TSQE. There follows a discussion of the development of a suitable discriminant function to identify stable stocks. The need for an optimal strategy to build investment portfolios is then explained in the light of the basic tenets of financial engineering. A strategy is then proposed based on product parameter design; and portfolio returns are compared with market returns. Finally, the paper presents concluding remarks and suggestions for future work.