Mitsubishi Heavy Industries (Germany)

During the last fifty years steam pressure and temperature in fossil-fired power plants have been continuously raised to improve thermal efficiency. Recent efforts for raising steam conditions are in response to the social demand for environmental protection as well as energy conservation concerns. Today the steam temperature of 600°C for modern power plants equipped with swing load or sliding pressure demand functions has already been realized, and a goal for the future is the 630°C to 650°C class with ferritic steels.However the 600°C to 630°C class is possible for current construction, based on already developed materials that include ferritic steels for pipework and rotors. Numerous studies on heat resistant steels actively conducted since the early 1970s have allowed great progress in both 9–12% Cr steels and austenitic steels. This paper presents a historical view of developments in steam pressure and temperature of fossil-fired power plants and alloy design for heat resistant steels in the 20th century, particularly over the last severaldecades, as well as a survey of the current status of steel development for power plants, mainly with regard to creep strengthening and enhancement of corrosion resistance.

In the zero-emission electric power generation system, a multiple-input DC-DC converter is useful to obtain the regulated output voltage from several input power sources such as a solar array, wind generator, fuel cell, and so forth. A new multiple-input DC-DC converter is proposed and analyzed. As a result, the static and dynamic characteristics are clarified theoretically, and the results are confirmed by experiment.

Fatigue crack initiation behavior of low-alloy steel in 90 C deionized water was investigated. It was observed that the corrosion fatigue process composed three stages, namely, pit growth, crack formation from the pit, and corrosion fatigue crack propagation. The pit size was found to increase with time (t) following the relation: pit size ∝ t1/3. The crack formation from the pit was determined from the stress intensity factor (linear elastic fracture mechanics parameter), which was calculated by assuming that the pit was a sharp crack. The critical pit condition (ΔK)P was 1.2 MPam for 2.5NiCrMoV and 3.5NiCrMoV in 90 C water containing dissolved oxygen. Using these results, a residual life prediction method for fatigue crack initiation based on in-service inspection was proposed.

The development of system-on-silicon large-scale integration (LSI) devices has significantly influenced the demand for higher wiring connectivity within LSI chips. Currently, increasing the number of metal layers in a multilevel metallization as the device size decreases increases wiring connectivity. In the future, however, designers will have difficulty catching up with the rising demand for higher wiring connectivity by merely increasing the number of metal layers. We propose a new three-dimensional integration technology to overcome future wiring connectivity crises. In our solution, several vertically stacked chip layers in 3D LSI chips or 3D multichip modules (MCMs) are fabricated using our new integration technology. More than 10/sup 5/ interconnections per chip form in a vertical direction in these 3D LSI chips or 3D MCMs. Consequently, we can dramatically increase wiring connectivity while reducing the number of long interconnections.

Segmented polyurethanes containing soft segments with lower molecular weight exhibit shape-memorizing properties. Structure and properties of shape-memorizing polyurethanes (S-PUs) were studied. S-PUs are characterized by a rather high glass transition temperature: Tg of S-PUs is usually in the range of 10–50°C. A Pplot of 1/Tm against–In XA is approximately linear, indicating that the hard segments are randomly distributed along the molecular chain. S-PUs with a hard segment of 67–80 mole % form negative spheruiites; they give a faint scattering maximum in a small-angle X-ray diffraction pattern. On the other hand, S-PUs with a hard segment of 50 mole % form fine birefringent elements, giving diffuse scattering in its SAXD pattern. A cyclic test of an S-PUs above Tg indicates that the residual strain increases and the recovery strain decreases with increasing cycle and maximum strain. It has been suggested by dynamic mechanical investigation that the shape-memorizing property of the S-PUs may be ascribed to the molecular motion of the amorphous soft segments. © 1996 John Wiley & Sons, Inc.

The fracture surfaces of specimens of a heat‐treated hard steel, namely Cr–Mo steel SCM435, which failed in the regime of N = 10 5 to 5 × 10 8 cycles, were investigated by optical microscopy and scanning electron microscopy (SEM). Specimens having a longer fatigue life had a particular morphology beside the inclusion at the fracture origin. The particular morphology looked optically dark when observed by an optical microscope and it was named the optically dark area (ODA). The ODA looks a rough area when observed by SEM and atomic force microscope (AFM). The relative size of the ODA to the size of the inclusion at the fracture origin increases with increase in fatigue life. Thus, the ODA is considered to have a crucial role in the mechanism of superlong fatigue failure. It has been assumed that the ODA is made by the cyclic fatigue stress and the synergetic effect of the hydrogen which is trapped by the inclusion at the fracture origin. To verify this hypothesis, in addition to conventionally heat‐treated specimens (specimen QT, i.e. quenched and tempered), specimens annealed at 300 °C in a vacuum (specimen VA) and the specimens quenched in a vacuum (specimen VQ) were prepared to remove the hydrogen trapped by inclusions. The specimens VA and VQ, had a much smaller ODA than the specimen QT. Some other evidence of the influence of hydrogen on superlong fatigue failure are also presented. Thus, it is concluded that the hydrogen trapped by inclusions is a crucial factor which causes the superlong fatigue failure of high strength steels.

BACKGROUND AND AIMS: Fatty liver is not uncommon in many countries, including Japan, and is mainly caused by alcohol usage and obesity. The aim of this study was to determine the incidence and causative factors of fatty liver in Japanese adults. METHODS: The clinical characteristics of 3432 Japanese adults who visited our hospital between January and December 2000 for thorough medical examinations were recorded including sex, age, body mass index (BMI), percentage body fat measurement using a bipedal bioimpedance instrument, history of alcohol intake, blood pressure, serum levels of aspartate aminotransferase, alanine aminotransferase (ALT), gamma-glutamyl transpeptidase, total cholesterol, triglyceride, uric acid, fasting blood glucose (FBG), and liver status by ultrasonography (USG). RESULTS: Of 3432 participants, 747 (21.8%) were diagnosed as having fatty liver by USG, 1873 (54.6%) were 'daily alcohol drinkers', and 698 (20.3%) were overweight (BMI >or= 25 kg/m2). Fatty liver was more frequent in men and overweight subjects (P < 0.01), whereas there was no significant difference in the proportion of the 'daily alcohol drinker' between fatty liver and non-fatty liver participants. The logistic regression analysis showed that BMI, ALT, and triglyceride were independent predictors of fatty liver in both sexes, and FBG, uric acid, percentage body fat, and total cholesterol were independent predictors of fatty liver only in men. It was noted that 319 (9.3%) were non-alcoholic individuals with fatty liver, and 141 (4.1%) were non-alcoholic and non-overweight individuals with fatty liver. The logistic regression analysis showed that percentage body fat was an independent predictor of fatty liver in non-alcoholic and non-overweight participants in both sexes, although non-significant in women in the whole group. CONCLUSIONS: In our study population, 21.8% had fatty liver diagnosed by USG, 9.3% were non-alcoholic with fatty liver, and 4.1% were non-alcoholic and non-overweight with fatty liver. Our results suggest that central body fat distribution can correlate with the development of fatty liver, and that measurement of percentage body fat is useful to assess the etiology of fatty liver in non-alcoholic and non-overweight participants, particularly women.

Abstract The joint quality of deep-penetration laser beam welding is related to the keyhole behaviour, e.g. keyhole-induced porosities. In this paper, a model which considered the existence of three phases, including plasma gas, liquid metal and solid metal, was proposed to describe the keyhole phenomena of laser welding. The forces of interaction of fluid dynamics in the keyhole and molten pool were modelled using the CFD software, and an adaptive heat source model was proposed for the absorption of laser energy. The molten pool and keyhole phenomena of laser beam welding were simulated using the developed model, as well as the formation of keyhole-induced porosities. It was found that the keyhole depth self-fluctuates in continuous laser welding, and the bubbles formed from keyhole collapse and shrinkage are the cause of keyhole-induced porosity.

Experiments on the effect of casing treatment were carried out using low-speed axial-flow compressors. Results on the overall compressor performance and on the flow through the blade row as well as the flow within the treatment slots are presented. Then, based on the experiments, a possible mechanism of the stall margin improvement is suggested.

Digital twin networks (DTNs) are real-time replicas of physical networks. They are emerging as a powerful technology for design, diagnosis, simulation, what-if-analysis, and artificial intelligence (AI)/ machine learning (ML) driven real-time optimization and control of the sixth generation (6G) wireless networks. Despite the great potential of what digital twins can offer for 6G, realizing the desired capabilities of DTNs requires tackling many design aspects including data, models, and interfaces. In this article we provide an overview of DTNs by presenting prominent use cases and their service requirements, describing a reference architecture, and discussing fundamental design aspects. We also present a real-world example to illustrate how DTNs can be built upon and operated in a real-time reference development platform - Omniverse.

High cycle fatigue fracture surfaces of specimens in which failure was initiated at a subsurface inclusion were investigated by atomic force microscopy and by scanning electron microscopy. The surface roughness R a increased with radial distance from the fracture origin (inclusion) under constant amplitude tension–compression fatigue, and the approximate relationship: R a ≅ C Δ K 2 I holds. At the border of a fish‐eye there is a stretched zone. Dimple patterns and intergranular fracture morphologies are present outside the border of the fish‐eye. The height of the stretch zone is approximately a constant value around the periphery of the fish‐eye. If we assume that a fatigue crack grows cycle‐by‐cycle from the edge of the optically dark area (ODA) outside the inclusion at the fracture origin to the border of the fish‐eye, we can correlate the crack growth rate d a/ d N , stress intensity factor range Δ K I and R a for SCM435 steel by the equation and by d a/ d N proportional to the parameter R a . Integrating the crack growth rate equation, the crack propagation period N p2 consumed from the edge of the ODA to the border of the fish‐eye can be estimated for the specimens which failed at N f &gt; 10 7 . Values of N p2 were estimated to be ∼1.0 × 10 6 for the specimens which failed at N f ≅ 5 × 10 8 . It follows that the fatigue life in the regime of N f &gt;10 7 is mostly spent in crack initiation and discrete crack growth inside the ODA.

A new simple technique is presented to extract ships from synthetic aperture radar (SAR) images. The procedure is to compute the cross-correlation values between two images extracted by moving windows of a small size from the multilook SAR intensity (or amplitude) images. A coherence image, consisting of the cross-correlation values of the intensity images, is then produced. Ships are deterministic targets, so that their interlook subimages possess higher degree of coherence than the uncorrelated random images of the surrounding sea surface. The main advantage of this method over the conventional constant false-alarm rate is its ability to detect, under favorable conditions, "invisible" images of ships embedded in the speckled image of the sea surface. The technique is tested using a RADARSAT-1 image in which one known and several unknown ships are present. The use of complex images and the exploitation of short decorrelation times of small-scale ocean waves to obtain an extra look are also discussed.

A series of rare‐earth zirconate Ln 2 Zr 2 O 7 ceramics (Ln=Dy, Er, and Yb) with a fluorite structure (F‐Ln 2 Zr 2 O 7 ) were prepared by pressureless sintering from zirconia and rare‐earth oxide powders at 1600°C for 10 h in air. The microstructure experiments were performed by X‐ray diffractometry (XRD) and scanning electron microscopy (SEM). The thermal conductivity and thermal expansion of these ceramics were evaluated using a steady‐state laser heat‐flux technique and high‐temperature dilatometry, respectively. The XRD and SEM results demonstrate that Ln 2 Zr 2 O 7 ceramics with a single fluorite phase are synthesized and no other phases are found. The results of thermal conductivity show that their thermal conductivities (1.3–1.9 W/(m·K), 20°–800°C) are as low as those of the referenced Ln 2 Zr 2 O 7 ceramics (Ln=La, Nd, Sm, and Gd) with pyrochlore structure (P‐Ln 2 Zr 2 O 7 ). It is concluded that rare‐earth zirconate ceramics with a fluorite structure can be considered as candidate materials for future thermal barrier coatings.

The individual electrode processes from anode and cathode have been clearly identified from practical impedance spectra with high-frequency inductive impedances for the Mitsubishi segmented-in-series tubular solid oxide fuel cell by combining the distribution of relaxation time analysis and the complex nonlinear least square fitting. Anodic gas diffusion process and charge transfer reaction near anodic triple phase boundary appear at and , respectively. Cathodic oxygen reduction processes appear at at , whereas the impedance arc over is dominated by the cathodic oxygen ion transfer through the (LSM)/-stabilized (YSZ) interface and YSZ of the composite. The results also exhibit an excellent agreement with those from the analysis of difference in impedance spectra.

Elemental analysis of Pd complexes, which consist of a thin Pd layer, alternating CaO and Pd layers and bulk Pd, is described, after subjecting the Pd complexes to D2 gas permeation. The Pd complex was located in a vacuum chamber and the elemental analysis was performed using an X-ray photoelectron spectroscopy (XPS) apparatus mounted on the chamber. When Cs was added on the surface of a Pd complex, Pr emerged on the surface while Cs decreased after the Pd complex was subjected to D2 gas permeation at 343 K and 1 atm for about one week. In the case of adding Sr on the surface, Mo emerged on the surface while the added Sr decreased after D2 permeation for about two weeks. All the phenomena were reproduced qualitatively. The isotopic composition of the detected Mo exhibited characteristics indicating an isotopic abundance of Sr rather than the natural abundance of Mo.

Abstract The plastic deformation behaviour of polysynthetically twinned (PST) Ti-Al with three different orientations has been studied in tension and compression as a function of temperature in a range from −196 to 1100°C. With increase in temperature, the yield stress decreases rather rapidly at low temperatures and then decreases gradually at intermediate temperatures for all orientations studied although the temperature dependence at low temperatures is less significant for an orientation where shear deformation occurs parallel to the lamellar boundaries. When the loading axis is perpendicular to the lamellar boundaries, the yield stress again rapidly decreases with increasing temperature at high temperatures. This is also the case for PST Ti-Al whose lamellar boundaries are parallel to the loading axis, although a small and broad anomalous yield stress peak is observed at 800°C for this orientation. When the lamellar boundaries are inclined at an intermediate angle to the loading axis, the yield stress gradually decreases with increasing temperature without showing any anomalous peak or rapid decrease at high temperatures. For the parallel and intermediate orientations, the tensile elongation is constant up to 200°C and begins to increase with increasing temperature at 400°C and continues to increase until 600°C. Above 800°C, tensile deformation for these two orientations is accompanied by the occurrence of necking at the part of specimens where recrystallization starts. For the perpendicular orientation, the tensile elongation is essentially zero at all temperatures studied and fracture occurs always parallel to the lamellar boundaries, indicating the weakness of such boundaries under tensile stress even at high temperatures.

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> YBCO superconducting wire has a relatively low decrease in power distribution at high temperatures and under a high magnetic field. A high-intensity substrate is used for the wire, so the wire has high machine characteristics. Therefore, it is expected that this wire can be used for large-scale high magnetic field coils. Here, coordination between the SMES system for 100 MVA/2 GJ class load fluctuation compensating was conducted using IBAD/CVD-YBCO wire. The SMES system includes a toroidal type YBCO coil consisting of 180 compact, high magnetic field multi-unit coils, a large coil cooling system that uses the conduction cooling method, which does not use a refrigerant medium, and a multi-cell power converter that achieves multi-unit coil connection with relatively low current and low voltage. Studies were conducted for each individual device and for the whole system. Based on the study plan in this paper, it has become possible to develop and coordinate each device of the 100 MVA/2 GJ class power system load fluctuation compensation SMES system using YBCO wire, which up until now had seem impossible as an actual system. </para>

The purpose of the present paper is to investigate the structure of the laminar–turbulent transition region for the three-dimensional boundary layer along a 30° cone rotating in external axial flow. Spiral vortices, which were assumed as small disturbances in the present stability analysis, are observed experimentally in the transition region. The process of transition to a turbulent boundary layer is visualized in detail. When the ratio of rotational speed to external axial flow is increased, the critical and transition Reynolds numbers decrease remarkably. The spiral angle and the number of vortices appearing on the cone decrease as the rotational speed ratio is increased.

The influence of CO2, SOx, NOx and soot dust on the productivity of microalgae was considered using Nannochloropsis salina and Phaeodactylun tricornutum. Microalgae are viewed as a possible means of combeting global warming.These microalgae can be easily cultivated in a high CO2 gas concentration of 15 vol%.SO2 gas itself does not influence the growth of microalgae. However, when the SO2 concentration is high, the pH of the medium decreases and the productivity of the microalgae is lowered.The presence of NO does not influence the growth of microalgae. NO absorbed in the medium is changed to NO2– and utilized as a nitrogen source.As for Ni and V contained in soot dust, when the dissolved concentrations of these metals in the medium exceed more than 1 and 0.1 ppm, respectively, the microalgae productivity decreases, however, under actual conditions, their concentrations are normally lower than these values.The above results obtained in a small scale test using a simulated gas were confirmed in a field test using a raceway-type reactor with actual flue gas.

Abstract The kinetics of the reaction of CO2 with secondary an alkanolamine linked with alkyl group, methylaminoethanol (MAE), ethytaminoethanol (EAE) and n-butylaminoethanol (BAE), for CO2 recovery from power plant flue gases was investigated using a stirred tank absorber with a plane unbroken gas-liquid interface at 298 K. To evaluate the reaction rate constant from the CO2 absorption rate data under the fast-reaction regime, a combined parameter containing the solubility and diffusivity for N2O in aqueous solutions of sterically hindered amines; MAE, EAE and BAE, was measured using a wetter-wall column apparatus at the same temperature. For further practical evaluation of the reaction rate, apparent rate constants for EAE under the process condition of CO2 removal from power plants were investigated.