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GIL/GIS bus is widely used in the field of power transmission and distribution, and the demand for lightweight is becoming more and more prominent. To reduce the weight of the bus and ensure the safety and reliability of the structure, a new 6σ robust design method of the GIL/GIS bus based on electric‐thermal‐mechanical co‐simulation is proposed. Taking a 550 kV/5000A bus as the initial structure, considering the uncertainty of product size and performance, a 6σ robust lightweight model of bus insulation electric field strength, current temperature rise, and mechanical stress multi‐performance co‐simulation is established. The finite element numerical calculation method is used to calculate and analyze the performance parameters of the bus. The Kriging surrogate model is used to form the response surface, and the optimal bus structure is obtained by genetic algorithm. The results show that after the robustness optimization, the performance of the bus meets the design requirements, the weight per meter decreased from 65.11 to 39.12 kg, and the lightweight effect is remarkable. Compared with the traditional deterministic optimization design, the reliability of the structure is improved. The new method of the GIL/GIS bus lightweight design proposed in this study has high feasibility and application prospects, which can provide new ideas for the development of gas‐insulated electrical equipment. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Earthquakes with magnitudes of 6–7 have been reported even in various active tectonic settings where fault deformation topography have not been detected. Therefore, delineating concealed active faults generating such earthquakes is necessary to reduce earthquake damage; however, few studies exist to provide its clues regarding such faults. The 1984 Western Nagano Earthquake in Japan was a main shock with a magnitude of Mj 6.8 and a depth of 2 km at the source. Solid bedrocks are well‐exposed in the earthquake source region; however, no surface rupture have been identified, and the active fault is known to be concealed. In this study, we collected data on striations observed in fractures by geological survey around the source area of the 1984 Western Nagano Earthquake. Using the collected data, the multiple inverse method was used to estimate the stresses that affected the striation formation. Consequently, stresses similar to acting faults in this area were detected in minor faults around the known concealed active fault. This suggests that the minor faults might be part of the damage zone that has been developed around the concealed active fault. Some minor faults were recognized in Quaternary volcanic rocks, confirming that they experienced displacements recently. This study indicates the possibility of detecting concealed active faults in the bedrock by geological survey. Plain Language Summary: The activity of active faults causes earthquakes. Therefore, it is crucial to understand the distribution of active faults to prepare for earthquakes in advance. However, earthquakes can also occur where active faults have not been recognized. In this case, the active fault cannot be recognized on the surface but might be concealed. In this study, we collected data on many slip marks on fractures in the bedrock where a concealed active fault has been inferred and estimated the stress required to form the slip marks to examine whether a clue to the existence of a concealed active fault can be obtained from a surface approach. Consequently, similar stresses to currently acting faults in this area were obtained in the area directly above the concealed active fault. This discovery shows that there are many recently moved slip marks directly above the concealed active fault, which might be related to the activity of the fault. This result indicates the possibility of recognizing the concealed active fault from surface approaches. Key Points: We collected minor faults‐slip data around the 1984 Western Nagano Earthquake region, and conducted a multiple inverse methodAs results, the minor faults were active in the recent stress are concentrated just above the concealed active faultIt shows the possibility of understanding the existence of the concealed active fault by using our method even in no active fault areas [ABSTRACT FROM AUTHOR]

This article examines a case study involving a 3D‐printed titanium "aero base handlebar" that failed and caused a crash during the Japan 2020 Olympics. The failure was attributed to the handlebar's design, which did not meet the increasing demands of customers in terms of safety, cost, reliability, and comfort. The handlebar was created using in‐house Altair product tools like Inspire Studio, SIMSOLID, and SULIS. Static structural analysis was conducted by estimating boundary forces. The analysis revealed that the original handlebar design, with a width of 50 mm, did not meet the required safety standards. To address safety concerns, the article proposed moving the arms forward by 35 mm (1.37 in.) to create clearance and attempting to secure a modified aero handlebar with an 85 mm width. The modified design incorporated a lattice structure, which exhibited higher levels of deformation and stresses, as well as lower maximum fatigue damage compared to the original 50 mm design. These results highlight the importance of considering customer expectations for safety, reliability, and comfort. Company Altair's advanced proprietary software, including Inspire Studio, SIMSOLID, and SULIS, in addition to employing lattice optimization methods, can support designers and engineers in fulfilling these requirements and creating products that are both safer and more reliable. [ABSTRACT FROM AUTHOR]

Quantifying the stress distribution or finding mechanically coupled areas on the plate interface is fundamentally important for conjecturing megathrust earthquakes that may occur in the future. Kinematically coupled areas, or slip deficit distributions, on plate interfaces were commonly estimated by geodetic‐data analyses. However, mechanically coupled areas are not identical to the kinematically coupled areas. The present study develops an inversion method to estimate the stress rate distribution as mechanically coupled areas. We apply this method to the Nankai trough subduction zone, southwestern Japan to detect mechanically coupled areas. Some of the estimated coupled areas correspond to the rupture areas of historical earthquakes. Others are in a deeper part, which may release the stress as aseismic slip. We then construct a rupture scenario that can occur in the Nankai trough in the future based on the estimated mechanical coupling, assuming that an effective stress accumulation period is 100 years. The scenario consists of a foreshock of MW 8.0 followed by an afterslip of MW 7.7 and a mainshock of MW 8.2. Although the moment magnitude of the afterslip is slightly smaller than the foreshock, the strain energy released by the foreshock is significantly larger than the afterslip. In order to compare events when the stress drops are significantly different, it is useful to use the minimum released strain energy, or available energy, to characterize the magnitude of the events. Plain Language Summary: The driving force that generates huge earthquakes originates from the frictional locking between overriding continental plate and subducting oceanic plate. How strong and which parts are locked along the plate interface provide us with critical information for megathrust earthquakes that may occur in the future. Significantly coupled areas along the plate interface can be detected by the analysis of ground deformation. However, it is difficult to obtain correct information about the stress of the locking. To quantify the coupling along the plate interface, this study develops a method to estimate the stress rate based on elastic mechanics. We apply the method to the Nankai trough, in southwestern Japan, to estimate the plate locking. Then, by using the estimated locking information, we create a scenario for a sequence of earthquakes. This consists of a foreshock, a mainshock, and a slow slip between the foreshock and the mainshock. This study provides a method to obtain critical information about the mechanics on the plate boundary based on which we can create megathrust rupture scenarios. Key Points: An inversion method for the shear stress rate distribution along a plate boundary is developedMechanically coupled areas are identified on the plate interface in the Nankai troughA possible scenario for a megathrust earthquake after an afterslip of a foreshock is proposed based on the coupling distribution [ABSTRACT FROM AUTHOR]

The high‐temperature canned electric‐actuated valve permanent magnet synchronous motor (CEAV‐PMSM) directly drives the valve load, which is prone to eccentricity operation, causing greater system vibration and shortening the valve operating life. In order to analyze the electromagnetic and structural characteristics of CEAV‐PMSM under different eccentricity faults, this paper uses analytical methods to derive the magnetic field distribution of the motor under normal and eccentricity conditions. Then, the Maxwell Stress Tensor method is used to derive the expression of the radial electromagnetic force under normal and eccentricity conditions, and the order of space–time harmonics that have a greater impact on CEAV‐PMSM are summarized. After that, the electromagnetic performance comparison of the three pole‐slot combinations under different eccentricity conditions, and the harmonic orders during eccentricity is analyzed by Fourier transform to obtain the optimal pole‐slot combination, which verified the correctness of the analytical calculations. In addition, the influence of different eccentricity conditions on the radial force density and unbalanced magnetic pull are studied. On this basis, the vibration response of the motor under eccentricity is analyzed, and the influence of the canned sleeve on the vibration performance of the motor is discussed. Finally, the modal analysis of CEAV‐PMSM is carried out to prevent the occurrence of resonance under eccentricity, which provides some references for reducing the vibration and noise of the canned electric‐actuated valve. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Aseismic megathrust slip downdip of the seismogenic zone is accommodated by either steady creep or episodic slow slip events (SSEs). However, the geological conditions defining the rheology of megathrust slip remain elusive. We examined exhumed subduction mélanges on Kyushu, Japan, which deformed at ∼370–500°C under greenschist to epidote‐amphibolite facies conditions, comparable to warm‐slab environments. The mélanges recorded fluid release and viscous shear localization associated with metasomatic reactions between juxtaposed metapelitic and metabasaltic rocks. Metasomatic reactions caused albitization of metapelite, resulting in depth‐dependent changes to megathrust rheology. In a mélange deformed at ∼370°C, very fine grained reaction products (metasomatic albite) facilitated grain boundary diffusion creep at stresses of ∼45 MPa, less than those in the surrounding metabasalt. Mineralogical and chemical changes during metasomatic reactions, and their field content, imply an onset of albite metasomatism at ∼350°C. Albite metasomatism therefore potentially contributed to decreased megathrust strength around the inferred thermally controlled base of the seismogenic zone. In a mélange deformed near the mantle wedge corner at ∼500°C, metasomatic reactions promoted local quartz vein formation and localized viscous shear at slow slip strain rates, during which the coarse‐grained metasomatic albite behaved as relatively rigid blocks in a viscous matrix. We suggest that albite metasomatism can facilitate changes in a megathrust slip mode with depth and may explain why slip mode changes from creep to SSEs with tremor with increasing depth. Plain Language Summary: Along tectonic plate boundaries, where one plate slips beneath another, plate movement occurs by processes including large and devastating earthquakes slipping at meters/second, very small earthquakes called tectonic tremor, slow slip events (SSEs) slipping at millimeters/day, and steady creep slipping at centimeters/year. However, the factors controlling where these different slip styles occur remain poorly understood. On Kyushu, Japan, ancient plate boundary rocks have been exposed by uplift and erosion. Our measurements of structures and rock chemistry in these rocks revealed that chemical reactions between subducted basalts and sediments may influence the plate boundary slip behavior. In rocks that deformed near ∼370°C, chemical reactions produced very fine grained rocks that caused local weakening within the plate boundary. This could explain why the plate boundary slip behavior changes from frictional to viscous near the downdip of the seismogenic zone at ∼350°C. In rocks that deformed at ∼500°C, near where slow slip and tremor events occur, chemical reactions promoted quartz vein formation that may represent tremor and localized viscous shear at faster strain rates than in surrounding rocks. This could explain the occurrence of tectonic tremors and SSEs. Key Points: Exhumed mélange shear zones deformed downdip of the seismogenic zone recorded albite metasomatism during subductionVery fine grained albite facilitated shear zone weakening by grain boundary diffusion creep near the base of the seismogenic zoneAlbite metasomatism promoted viscous shear localization at an increased strain rate near the mantle wedge corner [ABSTRACT FROM AUTHOR]

Application of Raman spectroscopy of carbonaceous material thermometry to samples of metasedimentary rock from the low‐grade Sanbagawa belt in the central Kii peninsula reveals a progressive decrease in temperature from ~390 °C close to the northern boundary, a major continental shear zone—the median tectonic line (MTL)—to ~270 °C and ~7 km to the south and roughly constant temperature distribution thereafter. Within the Sanbagawa belt, the thermal structure is not significantly modified by slip‐on fault boundaries between different geological units or folding. Meso‐ and microstructural observations combined with strain analysis using detrital grains in meta‐mudstone indicate a similar deformation history throughout the area and no correlation between ductile strain and temperature gradients. These observations suggest the observed thermal structure was developed after the main stages of ductile deformation of the Sanbagawa belt were complete and are not due to localized preferential exhumation along with the MTL. The observations also require a heat source along with the MTL. Order of magnitude estimates suggest the influx of warm fluid along the MTL are viable causes of the observed thermal anomaly. Although shear heating would be another possible explanation, thermal calculations require anomalous fast slip rates along the MTL and much greater frictional strength than generally considered reasonable. For these reasons, fluid infiltration is our preferred model. [ABSTRACT FROM AUTHOR]

Triggering of volcano seismic activity and eruptions by tides, atmosphere pressure, rainfall, and earthquakes have been in constant debate. However, there is limited evidence concerning the triggering of very‐long‐period signals (VLPs), which are closely linked to volcano conduit dynamics. Persistent and repetitive VLP event beneath the Aso volcano, historically termed long‐period tremor (LPT), manifests episodic pressurization and depressurization events in a crack‐like shallow conduit. Here we show that LPT activity display no appreciable spectral peaks associated with major diurnal/semidiurnal tidal constituents or barometric pressure. Instead, passing surface waves of ∼0.01 m/s from the 2011 Tohoku earthquake elevated LPT activity and preferentially increased the likelihood of depressurization events. We suggest that the hydrothermal reservoir near the LPT source behaves like a confined (unconfined) aquifer against short‐period (long‐period) stress. A high stress rate of ∼102 Pa/s is sufficient to enhance the permeability of the conduit plug/wall and preferentially promotes depressurization events. Plain Language Summary: At one of the most active volcanoes in Japan, Aso volcano, long‐period tremor (LPT) was first discovered in the 1930s by Prof. Sassa in Kyoto University and such LPT activity have persisted since. It offers a unique natural laboratory and controlled experiment to systematically explore how periodic loadings trigger or modulate LPT activity in a persistently degassing volcano equipped with a well‐developed hydrothermal system. After carefully considering the background noise level modulated by the local wind and meteorological condition, we find no evidence of modulation or triggering by tides, barometric pressure, or temperature. Systematic analysis of surface wave amplitudes from great earthquakes suggests a common triggering threshold (∼0.01 m/s) shared by LPT (pressure change events) in Aso and volcano‐tectonic earthquakes (brittle failure events) in some geothermal areas, supporting key processes of pressure oscillations and unclogging fractures by dynamic stress. Key Points: Repetitive very‐long‐period signals (VLP) in Aso volcano (aka long‐period tremor, LPT) do not show detectable response against major tidal constituents, barometric pressure and temperatureStrong surface waves from the 2011 Tohoku earthquake (> 0.01 m/s) preferentially modulate depressurization LPT events for several daysResponse of hydrothermal reservoir to pressure change induced by periodic loadings is likely stress‐rate dependent [ABSTRACT FROM AUTHOR]

The characteristics of shallow low‐frequency earthquakes (LFEs) are related to stress changes on the shallow plate boundary, which are important for understanding the megathrust earthquake cycle. The 5 September 2004 off the Kii Peninsula earthquakes (MJMA = 7.1, 7.4) occurred near the Nankai trough subduction zone, off southwest Japan. Ocean bottom seismometer observations from 22 September to 30 November 2004 detected many shallow LFEs among the ordinary aftershocks. During the observation period, the frequency of shallow LFEs steadily decayed with the exception of episodic activities, which were very sensitive to stress changes caused by tides and the 23 October 2004 Niigata earthquake (MJMA = 6.8). We also confirmed correlations between shallow LFEs and shallow very low frequency earthquakes, which suggest that these slow events represent the same slip phenomenon. These findings will contribute to clarifying the impact of LFEs on megathrust earthquakes. Key Points: We detected shallow low‐frequency earthquakes (LFEs) after the 2004 off Kii Peninsula earthquakes by using ocean bottom seismometersSome shallow LFEs are associated with very low frequency earthquakes, which suggests both slow earthquakes represent the same phenomenonEpisodic shallow LFEs are stochastic yet sensitive to stress changes caused by both the 2004 Niigata earthquake and tidal effects [ABSTRACT FROM AUTHOR]

The three‐dimensional (3‐D) deformation field associated with the 2016 Central Tottori earthquake is retrieved from advanced land observing satellite 2 interferometric synthetic aperture radar (InSAR) observations with four different viewing geometries, that is, ascending/descending tracks and left‐/right‐looking modes. The strain model and variance component estimation (SM, VCE, SM‐VCE) method is exploited and improved to integrate the InSAR observations with different viewing geometries so that the 3‐D deformation field is not affected by the inconsistent coverage of SAR footprints or the gross errors in InSAR observations. The obtained results are consistent with GNSS observations, indicating that the improved SM‐VCE method, known as SM‐RVCE in this paper, is capable of retrieving an accurate and spatially complete 3‐D deformation field for this earthquake. In addition, the precision of the InSAR observations and the estimated 3‐D deformation are quantitatively assessed by the SM‐RVCE method. Finally, on the basis of the estimated 3‐D coseismic deformation, the source parameters of this event are inverted, revealing an asperity with a maximum strike‐parallel slip of ~1.1 m concentrated at depths between 2 and 10 km. The estimated seismic moment is 2.4 × 1018 Nm, which corresponds to a Mw 6.2 event. Key Points: We retrieve the 3‐D deformation field of the 2016 Central Tottori earthquake from left‐ and right‐looking InSAR observationsWe conduct a precision assessment for InSAR observations based on the variance component estimation (VCE) methodWe employ the robust VCE method to mitigate the effects of gross InSAR errors such as unwrapping errors on the 3‐D deformation [ABSTRACT FROM AUTHOR]

SUMMARY We developed the 550-kV disconnectors that strengthened earthquake proofing by the addition of the damper unit and weight reduction of conductive part based on the damage of the 550-kV disconnectors by the Great East Japan earthquake (March 11, 2011) and inspected the earthquake proofing performance by shake table test. In shake table test, we performed the test by the artificial seismic wave that varied in phase characteristic in addition to the test by resonance method. And, in a high-level earthquake area, we analyzed it about the influence that a phase characteristic of the artificial seismic wave gave to stress to occur in disconnectors. As a result, it is thought that the stress to occur in disconnectors is decided by a primary natural frequency basically because a bending strain to occur to the disconnectors in the time when the resonance frequency ingredient becomes the big acceleration response value grows big. But, on a particular phase condition, it was confirmed that the bending strain to occur in disconnectors might grow big conspicuously. As for this, the possibility is thought about by influence of higher natural frequency doing superposition. [ABSTRACT FROM AUTHOR]

For the purpose of evaluating the fatigue strength of the Japanese railway wheel, fatigue testing was done on the actual size wheel, using a new resonance-type fatigue-testing machine. Because the maximum stress under the horizontal and vertical loads occurs at the wheel plate, the fatigue strengths of the wheel plate were measured and the safety factors versus design load were evaluated. Two kinds of typical Japanese railway wheel were tested and the results showed that their safety factors were larger than 2.4. [ABSTRACT FROM AUTHOR]

It is well known that one drawback for stress-ribbon bridges can be that significant horizontal reactions at the abutment can be generated and that they have low flexural stiffness. The latter prevents them from being used as roadway bridges. A new hybrid structure of stress-ribbon deck and truss has been proposed and was adopted in the construction of Nozomi Bridge in Japan, a roadway bridge opened to traffic in 2003. Static and dynamic behaviours of the hybrid structure have been studied analytically and experimentally. The results show that the hybrid bridge has advantages over the stress-ribbon deck bridge as it generates much less horizontal force in suspension cables and has higher flexural stiffness, suitable for use as a roadway bridge, and that the hybrid bridge has advantages over the truss bridge since it can be constructed without extensive falsework and without large erection equipment. In this paper, at first, the hybrid structure is described, then analytical and test results are used to show its static and dynamic characteristics, and finally the construction of Nozomi Bridge is outlined. [ABSTRACT FROM AUTHOR]

Evaluates the mechanical properties of adjacent flow weld line by researchers from Japan. Occurrence of weld lines at the interface of two adjacent flows of material behind an obstructive pin in a cavity in injection molding; Examination of the tensile strength of such adjacent flow weld line in injection molded polystyrene plates by a mechanical step-by-step milling technique; Elucidation on the dependence of weld line strength on the properties of the surface layer of the weld line.

A medium-sized, high magnetic field magnet was designed using data on the mechanical properties of Bi/Ag oxide tape superconductors. Due to the poor mechanical properties of tape superconductors, the size of a superconductive magnet is limited to a narrow region of radius and magnetic field. In order to build a large superconductive magnet, key mechanical properties of the Bi/Ag oxide tape superconductors, such as irreversible strain and matrix yield strength, have to be improved significantly. [ABSTRACT FROM AUTHOR]

Abstract Regional ductile deformation of the Sanbagawa belt is generally thought to be characterized by constrictional strain, based on strain analysis using deformed radiolarians in the low-grade regions. Similar strain analysis could not be carried out in the medium- to high-grade zones, because it is very difficult to identify individual radiolarians after strong recrystallization. However, discovery of the first known meta-conglomerate in the high-grade region of the Sanbagawa Belt allows quantitative 3-D strain to be estimated in this region. Using a development of the Rf-φ method, an evaluation of appropriate errors for this estimate can be determined. The principal strain ratios and estimated errors are X/Y = 5.4–6.6 and Y/Z = 3.8–3.9 implying deformation in the flattening field and refuting the idea of uniform constrictional strain. Semi-quantitative markers of the shape of the strain ellipse throughout the high-grade regions suggest that the deformation of the Sanbagawa Belt is dominantly in the flattening field. The difference with the earlier results may be due to late-stage overprinting by upright folding of the main ductile fabric in the low-grade region of western Shikoku. [ABSTRACT FROM AUTHOR]