Case-carburizing of helical gears with large helix angles may form too large hardened layers near the tooth width end on the acute angle side (ACUTE-END), and adversely affect the bending fatigue strength. We investigated the bending fatigue strength of casecarburized helical gears with large helix angles up to approximately 40° through a bending fatigue test, hardness test, and residual stress measurement. We found that the case-carburizing formed large hardened layers near ACUTE-END, reduced the compressive residual stress near ACUTE-END, and restricted the improvement of the bending fatigue strength in a meshing state where tooth root stress became large near ACUTE-END. Based on the obtained bending fatigue limits, we revealed that ISO 6336-3:2006 overestimated the rate of increase of the permissible circumferential loads for helix angles exceeding approximately 30°, and ISO/DIS 6336-3:2018 underestimated this rate for helix angles near 30°.
In recent years, we have experienced mega‐flood disasters in Japan due to climate change. In the last century, we have been building disaster prevention infrastructure (artificial levees and dams, referred to as “grey infrastructure”) to protect human lives and assets from floods, but these hard protective measures will not function against mega‐floods. Moreover, in a drastically depopulating society such as that in Japan, farmland abandonment prevails, and it will be more difficult to maintain grey infrastructure with a limited tax income. In this study, we propose the introduction of green infrastructure (GI) as an adaptation strategy for climate change. If we can use abandoned farmlands as GI, they may function to reduce disaster risks and provide habitats for various organisms that are adapted to wetland environments. First, we present a conceptual framework for disaster prevention using a hybrid of GI and conventional grey infrastructure. In this combination, the fundamental GI, composed of forests and wetlands in the catchment (GI‐1) and additional multilevel GIs such as flood control basins that function when floodwater exceeds the planning level (GI‐2) are introduced. We evaluated the flood attenuation function (GI‐1) of the Kushiro Wetland using a hydrological model and developed a methodology for selecting suitable locations of GI‐2, considering flood risk, biodiversity and the distribution of abandoned farmlands, which represent social and economic costs. The results indicated that the Kushiro Wetland acts as a large natural reservoir that attenuates the hydrological peak discharge during floods and suitable locations for introducing GI‐2 are concentrated in floodplain areas developing in the downstream reaches of large rivers. Finally, we discussed the network structure of GI‐1 as a hub and GI‐2 as a dispersal site for conservation of the Red‐crowned Crane, one of the symbolic species of Japan. 相似文献
Cross‐modal correspondences in the human sensory systems often appear for different levels of sensory inputs, such as colour and odour. However, whether there is hormonal modification of such colour‐odour correspondence has remained unclear. Here, we experimentally investigated the influence of hormonal changes in menopausal women by conducting evaluations of colour and odour impressions, matching tasks between colour and odour, and odor identification tasks, comparing two groups of women: premenopausal and postmenopausal. The results showed that both premenopausal and postmenopausal women had similar impressions and images of colours for odors, while postmenopausal women had significantly lower abilities of odor identification than premenopausal women. This suggested that the degree of conviction about an odor's identification might slightly affect the subjects’ impressions of odors and their corresponding colour choices. Menopause might not directly affect cognitive aspects regarding colour or odor, but might instead affect their perceptions. 相似文献
Women might experience modulation in their perception and cognition of colours and odours during the menstrual cycle, but how women's impressions of and correspondence between colours and odours differ according to the cycle changes remains unknown. Here, we experimentally examined women's performance of several tasks, including evaluation of impressions of colours and odours, matching/nonmatching of colours with odours, and identification of odours, comparing two phases: the beginning of menstruation and ovulation. The results showed that participants had similar impressions of colours and odours and made similar colour choices for odours in both the menstrual and ovulation phases, while “pleasant-unpleasant” impressions of colour and odour might vary according to the menstrual cycle. We found no significant differences in odour identification between the phases. The findings imply that hormonal changes during the menstrual cycle might affect “pleasant-unpleasant” impressions of colour and odour but not other features regarding impressions or crossmodal correspondence. In future studies, examination with a large number of participants is necessary. 相似文献
Wireless Networks - A Wireless Internet-access Mesh NETwork (WIMNET) provides scalable and reliable internet access through the deployment of multiple access points (APs) and gateways (GWs). In... 相似文献
Stable and metastable phase relationships in the system ZrO2–ErO1.5 were investigated using homogeneous samples prepared by rapid quenching of melts and by arc melting. The rapidly quenched samples were annealed in air for 48 h at 1690°C or for 8 months at 1315°C. Two tetragonal phases ( t - and t '-phases) were observed after quenching samples heated at 1690°C to a room temperature, whereas one t -phase and cubic ( c -) phase were found in those treated at 1315°C. Since the t '-phase is obtained through a diffusionless transformation during cooling from a high-temperature c -phase, t - and c -phases can coexist at high temperature. The t - and c -phases field spans from 4 to 10 mol% ErO1.5 at 1690°C and from 3 to 15 mol% ErO1.5 at 1315°C. The equilibrium temperature T t-m 0 between the t - and monoclinic ( m -) phases estimated from As and Ms temperatures decreased with increasing ErO1.5 contents. 相似文献
Diamond and diamond-ultrafine Co powder mixtures were sintered at 7.7 GPa and 1800° to 2000°C. A well-sintered body with a fine-grained homogeneous microstructure, high hardness, and high electrical resistivity was produced when a diamond-5 vol% Co powder mixture was used as the starting material. 相似文献
The hydration of layered double hydroxides (LDHs) was investigated by changing the interlayer anion species, the Mg/Al ratio of the LDH hosts and the relative humidity (RH). The anions were CO32−, Cl−, Br−, NO3−, I−, SO42−, and ClO4− (listed in the order of ion size, small to large) and LDHs with Mg/Al = 1.90 (LDH2) and 2.91 (LDH3) were used. Their XRD profiles were measured by an XRD diffractometer while controlling the RH in the range 0–95% at 25 °C. Only I−, SO42−, and ClO4− LDH2s and SO42− LDH3 showed a large step-wise basal-spacing expansion, 0.24–0.28 nm, under high RH conditions (> ca. 60%) probably due to the insertion of one water layer into the interlayer space. Such hydration occurred more favorably for the LDHs with larger anions and those with a higher layer charge (LDH2). Among them, I− and ClO4− LDH2s exhibited the second staging – alternate stacking of hydrated (H) and non-hydrated (NH) interlayers – in the intermediate RH region. 相似文献
True constant strain rate tensile tests of polypropylene up to 2% initial strain were performed to investigate the strain rate dependency of the initial stress–strain gradient dσ/dε with the aid of “slack grip.” The experimental results fairly agree with even the simplest mechanical model analysis with three parameters, showing the conspicuous strain rate dependency on the initial stress–strain gradient dσ/dε. The limiting cases corresponding to zero strain rate and strain rate of infinite magnitude, both predicted by the analysis, were experimentally verified. 相似文献