133 research outputs found
A theoretical framework for steady-state rheometry in generic flow conditions
No full textWe introduce a general decomposition of the stress tensor for incompressible fluids in terms of its components on a tensorial basis adapted to the local flow conditions, which include extensional flows, simple shear flows, and any type of mixed flows. Such a basis is determined solely by the symmetric part of the velocity gradient and allows for a straightforward interpretation of the non-Newtonian response in any local flow conditions. In steady homogeneous flows, the material functions that represent the components of the stress on the adapted basis generalize and complete the classical set of viscometric functions used to characterize the response in simple shear flows. Such a general decomposition of the stress is effective in coherently organizing and interpreting rheological data from laboratory measurements and computational studies in nonviscometric steady flows of great importance for practical applications. The decomposition of the stress in terms with clearly distinct roles is also useful in developing constitutive models.journal articl
Shear Jamming and Fragility of Suspensions in a Continuum Model with Elastic Constraints
No full textUnder an applied traction, highly concentrated suspensions of solid particles in fluids can turn from a state in which they flow to a state in which they counteract the traction as an elastic solid: a shear-jammed state. Remarkably, the suspension can turn back to the flowing state simply by inverting the traction. A tensorial model is presented and tested in paradigmatic cases. We show that, to reproduce the phenomenology of shear jamming in generic geometries, it is necessary to link this effect to the elastic response supported by the suspension microstructure rather than to a divergence of the viscosity
Microstructure and thickening of dense suspensions under extensional and shear flows
No full textDense suspensions are non-Newtonian fluids that exhibit strong shear thickening and normal stress differences. Using numerical simulation of extensional and shear flows, we investigate how rheological properties are determined by the microstructure that is built under flows and by the interactions between particles. By imposing extensional and shear flows, we can assess the degree of flow-type dependence in regimes below and above thickening. Even when the flow-type dependence is hindered, non-dissipative responses, such as normal stress differences, are present and characterise the non-Newtonian behaviour of dense suspensions
Predictions of microstructure and stress in planar extensional flows of a dense viscous suspension
No full textWe consider extensional flows of a dense layer of spheres in a viscous fluid and employ force and torque balances to determine the trajectory of particle pairs that contribute to the stress. In doing this, we use Stokesian dynamics simulations to guide the choice of the near-contacting pairs that follow such a trajectory. We specify the boundary conditions on the representative trajectory, and determine the distribution of particles along it and how the stress depends on the microstructure and strain rate. We test the resulting predictions using the numerical simulations. Also, we show that the relation between the tensors of stress and strain rate involves the second and fourth moments of the particle distribution function
Normal stress differences in dense suspensions
No full textThe presence and the microscopic origin of normal stress differences in dense suspensions under simple shear flows are investigated by means of inertialess particle dynamics simulations, taking into account hydrodynamic lubrication and frictional contact forces. The synergic action of hydrodynamic and contact forces between the suspended particles is found to be the origin of negative contributions to the first normal stress difference , whereas positive values of observed at higher volume fractions near jamming are due to effects that cannot be accounted for in the hard-sphere limit. Furthermore, we found that the stress anisotropy induced by the planarity of the simple shear flow vanishes as the volume fraction approaches the jamming point for frictionless particles, while it remains finite for the case of frictional particles
Nuchequula nuchalis
No full textNuchequula nuchalis (Temminck & Schlegel, 1845): Figure 3E, F Equula nuchalis Temminck and Schlegel 1845: 126. Leiognathus nuchalis — Eguchi et al. 2008: 19. Nuchequula nuchalis — Chakrabarty and Sparks 2007: 18; Kimura et al. 2008b: 22; Senou 2013: 902; Fujiwara and Motomura 2016: 197. Diagnosis. This species is characterized by the following combination of characters: mouth protruding downwards; small slender teeth on both jaws; anterior dorsolateral surface of body completely naked; black blotch on nape (Senou 2013). Distribution. Nuchequula nuchalis is known from Japan, the western and southern coasts of Korean Peninsula, Taiwan, and the coast of China. In Japanese waters, this species is known from the western coast of Aomori Prefecture to the southern part of the western coast of Kyushu (Sea of Japan coast), the eastern coast of Aomori Prefecture to the southern part of eastern coast of Kyushu, Seto Inland Sea, and Okinawa Island (Pacific coast) (Senou 2013). Remarks. The record of Nuchequula nuchalis in this study is based on 8 specimens (40.8–116.4 mm SL) from Kadogawa Bay in November and December. However, this species is caught frequently with shallow set nets (<10 m depth) for commercial purposes in the bay (author. Wada, pers. comm.). In addition, our survey did not record this species with the other deeper set nets, although we collected it from estuaries in Miyazaki Prefecture out of the survey period (KPM-NI 41550–41553, Kita-gawa river, northern part of Miyazaki Prefecture; KPM-NI 41888–41891, Hitotsuse-gawa river and Tondahama Lagoon, central Miyazaki Prefecture). These records indicate that N. nuchalis inhabits estuaries and shallow areas of the coasts of Miyazaki Prefecture.Published as part of Miki, Ryohei, Murase, Atsunobu & Wada, Masaaki, 2018, A checklist of ponyfishes (Teleostei, Leiognathidae) from Miyazaki Prefecture, east coast of Kyushu, southern Japan, with range extensions of three tropical species, pp. 243-255 in Check List 14 (1) on page 249, DOI: 10.15560/14.1.24
City Position of Importance in the Age of Honsyu-Shikoku Three Big Bridges : I
No full textMore than ten year ago Seto-Ohashi was constructed, last April Akashi-Kaikyo-Ohashi was completed, and this May Onomichi-Imabari route is going to be provided as the third road connecting Honsyu with Shikoku area. At the end of this century, as a result, Seto-uchi area has three main routes which would improve interregional mobility. Progress of traffic infrastructure could change city's economic position. On one side, some cities may grow by improving interregional accessibility. On the other side, however, some cities may lose their economic status due to so called 'straw effects'. This paper consists of two parts; the former part is focussed on recent regional economic changes and statistical analyses on city position of importance, the latter part is empirical investigation based on the results of questionnaire about city positions of importance. Regional recent changes mean office location and relocation as a firms' regional evaluations. In statistical analyses I propose a new indicator of city's relative economic importance. Questionnaire has been conducted for branch offices of major four cities in Seto-uchi area. Through questionnaire several evaluations of individual cities by corporate firms are clarified
INTERSTITIAL POLYCHAETES OF JAPAN II. -A NEW SPECIES OF HESIONURA FROM WESTERN JAPAN-
No full textHesionura, belonging to the family Phyllodocidae, is a genus mostly composed of interstitial species. Nine species and one subspecies have so far been recorded from various localities in the world. The present paper provides the first record of the genus from Japan. The materials from three localities in western Japan were examined. Their setae were especially observed under the phase contrast microscope of one thousand magnification. The result has revealed that they all represent a single new species, whose type specimens are preserved at the Osaka Museum of Natural History. I would like to express my hearty thanks to Prof. Eiji Harada of the Seto Marine Biological Laboratory for reading the manuscript. Thanks are also due to Mr. Yasuji Sakai of the Nansei Regional Fisheries Research Laboratory who has placed the material at my disposal
江木千之と文政審議会（1）－義務教育年限延長案の結末－
No full textEgi Senshi who was inaugurated as the Education Minister in January in 1924, newly organized the Council on Educational Affairs and proposed the draft of law for the two years expansion of the length of the term of the compulsory education. However, the Education Minister Okada Ryohei of the Cabinet under Premier Kato Takaaki who took power in June of the same year withdrew the draft. In this paper, the author makes much of a fact that Egi Senshi and Okada Ryohei were the same mind and makes clear the aims of the two persons which lurked in a conclusion.departmental bulletin pape
Seasonal variations of the prevalence of metabolic syndrome and its markers using big-data of health check-ups
No full textSeto H., Toki H., Kitora S., et al. Seasonal variations of the prevalence of metabolic syndrome and its markers using big-data of health check-ups. Environmental Health and Preventive Medicine 29, 2 (2024); https://doi.org/10.1265/ehpm.23-00216.Background: It is crucial to understand the seasonal variation of Metabolic Syndrome (MetS) for the detection and management of MetS. Previous studies have demonstrated the seasonal variations in MetS prevalence and its markers, but their methods are not robust. To clarify the concrete seasonal variations in the MetS prevalence and its markers, we utilized a powerful method called Seasonal Trend Decomposition Procedure based on LOESS (STL) and a big dataset of health checkups. Methods: A total of 1,819,214 records of health checkups (759,839 records for men and 1,059,375 records for women) between April 2012 and December 2017 were included in this study. We examined the seasonal variations in the MetS prevalence and its markers using 5 years and 9 months health checkup data and STL analysis. MetS markers consisted of waist circumference (WC), systolic blood pressure (SBP), diastolic blood pressure (DBP), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), fasting plasma glucose (FPG). Results: We found that the MetS prevalence was high in winter and somewhat high in August. Among men, MetS prevalence was 2.64 ± 0.42 (mean ± SD) % higher in the highest month (January) than in the lowest month (June). Among women, MetS prevalence was 0.53 ± 0.24% higher in the highest month (January) than in the lowest month (June). Additionally, SBP, DBP, and HDL-C exhibited simple variations, being higher in winter and lower in summer, while WC, TG, and FPG displayed more complex variations. Conclusions: This finding, complex seasonal variations of MetS prevalence, WC, TG, and FPG, could not be derived from previous studies using just the mean values in spring, summer, autumn and winter or the cosinor analysis. More attention should be paid to factors affecting seasonal variations of central obesity, dyslipidemia and insulin resistance
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