Deformation Behavior of Cementite in Deformed High Carbon Steel Observed by X-ray Diffraction with Synchrotron Radiation

The deformation behavior of cementite in drawn pearlitic steel and spheroidal cementite steel, which have hypereutectoid composition, was investigated by X-ray diffraction using synchrotron radiation. A detailed analysis of diffraction peak profiles reveals that the deformation behavior strongly depends on the shape of cementite in steel. The unit cell volume of the cementite in the drawn pearlitic steel compressively and elastically deforms by 1.5 to 2 pct of the initial volume at the early stage of drawing, whereas that in the drawn spheroidal cementite steel is compressed by 1 pct of the initial volume even at a large true strain. The cementite in the drawn pearlitic steel fragments into small pieces with increasing the true strain, and these pieces change to amorphous cementite. The dislocation densities of the cementite in the drawn pearlitic steel and in the drawn spheroidal cementite steel are estimated to be ~10¹³/m² before drawing and ~10¹⁴/m² after drawing. Although the large strain is induced in the cementite by drawing, the maximum strain energy in the cementite is too small to contribute to the dissolution of the cementite.

     

A simplified performance evaluation for bursty multiclass trafficin ATM systems

In broadband ISDN with ATM, various kinds of traffic, such as voice, data and video, share the common transmission resource. For such multiclass traffic systems, it is necessary to evaluate the grade of service (GOS) for individual traffic. In particular, for the ATM networks integrating voice and video which are of bursty property and delay sensitive, the individual performance evaluation for the mixed bursty traffic an important problem. The authors propose a simplified evaluation of the individual mean waiting time for the bursty multiclass systems appearing in the ATM network and show numerical examples for voice/video system     

Influence of Mn ion the action of dibutyryl cyclic AMP and forskolin on contraction, membrane response, and cyclic AMP-dependent protein kinase activity in rat myometrium

Contractile response, membrane activity, and protein kinase A (PKA) activity were measured on the longitudinal muscle taken from the estrogen-treated rat uterus, and the influence of Mn ion on the inhibitory effects caused by db cAMP and forskolin was investigated. Phasic contractions generated in the muscle taken from the middle portion of uterus were depressed to 48 and 83% by 30 microM db cAMP and 0.1 microM forskolin in Mg-free Krebs solution, respectively; phasic contractions were more strongly depressed by the agents in the solution containing 0.2 mM Mn. Action potentials consisted of spike and plateau components, and the duration of the plateau potential was reduced by the application of the agents; membrane activity was more strongly depressed in the presence of 0.2 mM Mn. The contractile depression caused by db cAMP was reduced and by forskolin was enhanced by pretreatment of the tissue with 0.6 mM Mn for 30 min. The PKA activity was increased by 39 and 6% of the control, when 30 microM db cAMP and 0.1 microM forskolin were applied, respectively; the PKA activity in response to db cAMP and forskolin was reduced and enhanced, respectively, when the tissues were pretreated with 0.6 mM Mn. It was proposed that Mn ions permeated into cell interior when the muscle was exposed to 0.6 mM Mn, so that the effects of the agents were differently affected. It was also shown that plateau potential dominated in the muscle taken from the ovarian portion, and the contractile inhibition caused by the agents was far weaker.     

Ductility Loss in Ductile Cast Iron with Internal Hydrogen

Hydrogen-induced ductility loss in ductile cast iron (DCI) was studied by conducting a series of tensile tests with three different crosshead speeds. By utilizing the thermal desorption spectroscopy and the hydrogen microprint technique, it was found that most of the solute hydrogen was diffusive and mainly segregated at the graphite, graphite/matrix interface zone, and the cementite of pearlite in the matrix. The fracture process of the non-charged specimen was dominated by the ductile dimple fracture, whereas that of the hydrogen-charged specimen became less ductile because of the accompanying interconnecting cracks between the adjacent graphite nodules. Inside the hydrogen-charged specimen, the interspaces generated by the interfacial debonding between graphite and matrix are filled with hydrogen gas in the early stage of the fracture process. In the subsequent fracture process, such a local hydrogen gas atmosphere coupled with a stress-induced diffusion attracts hydrogen to the crack tip, which results in a time-dependent ductility loss.     

Utilization of Multiphase Fluxes for the Dephosphorization of Hot Metal

Although steelmaking slags have been usually treated and studied as homogeneous liquids, they are actually mixtures of a liquid and solids in practical processes. CaO‐based refining flux that does not contain fluxing agents such as CaF₂ inevitably forms a heterogeneous slag in normal cases, and hence, it is defined as a “multiphase flux.” Efficient utilization of this type of flux would decrease the consumption of resources and the emission of CO₂, and thus, would reduce the load on the environment. Metallurgical studies on multiphase fluxes are limited, however, the physical chemistry and reaction kinetics of the same are important for the development of advanced refining processes. The reaction mechanism of dephosphorization using a multiphase flux at hot metal temperatures was investigated in this study. The reaction of a P₂O₅‐containing slag with solid CaO was studied by immersing a CaO disc in the slag. A CaO‐FeO layer was formed near the interface, and a solid solution of Ca₂SiO₄‐Ca₃P₂O₈ was observed in this layer. The Fe‐P‐Si alloy reacted with calcium ferrites at 1673 K, and the samples were analysed by XMA. The same solid solution (Ca₂SiO₄‐Ca₃P₂O₈) was observed near the slag‐metal interface, which suggests that the phosphorus removed from the metal gets concentrated in the solid phase. The experimental results were reproduced with a kinetic simulation model. The simulation program was also applied to the reaction of the CaO‐FeO droplet in a hot‐metal bath.     

The effects of external stress on the cubic-tetragonal transformation in rapidly quenched ZrO2-Y2O3

The effects of the external stress on the displacive cubic (c) to tetragonal (t) transformation, taking place during rapid quenching of ZrO₂-Y₂O₃ alloys by a hammer-anvil unit, were examined through the statistical analysis of the crystallography of the product phases. The initially formed c-phase had no strong texture with respect to the stress direction. However, specific t variants among crystallographically equivalent ones were formed preferentially. From these observations, it is concluded that the applied stress plays an important role on the deformation to change the lattice during the c t transformation.     

Robust ride comfort control of vehicles without measurements of tire deflection

In this article, a robust ride comfort control scheme for vehicles is proposed in which measurements of the tire deflections are not required. The controller has the property that we can specify a location where the ride comfort will be best. To achieve this end, an estimator for the tire deflections and the road disturbances is proposed. Next, a combined ideal vehicle is designed. In the ideal vehicle, the location where ride comfort will be best can be moved by setting only one design parameter. Finally, a robust tracking controller is developed so that a real vehicle tracks the motion of the combined ideal vehicle.     

FPC‐free LCD panel with capacitive coupling for transmission of signals and power

Abstract— A flexible‐printed‐cable (FPC) free liquid‐crystal‐display (LCD) panel by using a capacitive‐coupling technique has been developed. A QQVGAeight‐color image was successfully displayed for the first time without attaching any signal or power cables to the panel. The receiving circuitry and capacitive‐coupling electrodes were integrated on the LCD panel using a low‐temperature polysilicon (LTPS) fabrication process. In the proposed digital coding method, the receiving circuit converts derivative waveform signals via the capacitive coupling to conventional logic‐level signals. The maximum data rate of 2.4‐Mbps × 3ch (RGB) was achieved. In addition, LTPS low‐capacitance diode bridge and regulator enabled us to obtain stable DC power of 2.4 mW on the panel from the AC‐power signal. This study is the first step towards integrating the wireless‐communication function on the display panel to achieve a high‐value‐added flat‐panel display (FPD).     

Observer-based control of a manipulator system with structured uncertainty

In this article, we show a derivation of an uncertain system of a two-link RR manipulator with uncertainties in the two rotation angles of each joint. For this system, we apply a guaranteed cost control based on a linear upper bound. In our method, uncertainties are included in the state, input, and also output matrices. Parameter tuning of γ _i in the linear upper bound is effective in designing a feedback gain which has appropriate characteristics. In the numerical simulation, we show that the state observer is effective at reducing the influence of signal noise in a state vector.