2,597 research outputs found
Extended “Mononobe-Okabe” Method for Seismic Design of Retaining Walls
No full textMononobe-Okabe (M-O) method is still employed as the first option to estimate lateral earth pressures during earthquakes by geotechnical engineers. Considering some simple assumptions and using a closed form method, M-O solves the equations of equilibrium and suggests seismic active and passive lateral earth pressures. Therefore, the results are true in its assumption range only, and in many other practical cases, M-O method is not applicable. Noncontinues backfill slopes, cohesive soils, and rising water behind the wall are some well-known examples in which the M-O theory is irrelevant.
Using the fundamental framework of M-O method, this study proposes an iterative method to overcome the limits of the M-O method. Based on trial and error process, the proposed method is able to cover many of the defects which regularly occur in civil engineering when M-O has no direct answer
Modeling and Simulation of a 3D Printer Based on a SCARA Mechanism
No full textThis work presents a dynamic simulation of four arms SCARA (Selective Compliance Articulated Robot for Assembly) mechanism used in 3D printers in an multidisciplinary free software. Different extruder heads, motor supply voltage and microstepping strategies were simulated to show their impact on the construction of the printed part. To do the complete analysis of the printer, it is necessary to simulate the workflow to print a part. The steps of this workflow are part modeling, G-code generation, G-code translation, inverse kinematic analysis, motion translation and dynamic analysis. After accomplishing these steps, the computation of the positioning error completes the analysis. The simulation showed that the microstepping strategy had the greater influence on the construction of the part. The extruder mass became particularly relevant when the voltage was reduced. Simulation of the complete system also showed that electrical and mechanical components can be integrated in one model, although the behavior of components of one domain can restrict the simulation performance of the entire system
Dynamic Modeling of a 3D Printer Based on a Four Arms Scara Mechanism
No full textThis work presents the dynamic simulation of a four arms SCARA (Selective Compliance Articulated Robot for Assembly) mechanism used in 3D printers in a multidisciplinary free software. Different extruder heads and motor supply voltage were simulated to show their impact on the construction of the printed part. To do the complete analysis of the printer, it is necessary to simulate the workflow to print a part. The steps of this workflow are part modeling, G-code generation, G-code translation, inverse kinematics analysis, motion translation, and dynamic analysis. After accomplishing these steps, the computation of the positioning error completes the analysis. The simulation showed that the supply voltage has the greater influence on the construction of the part. The extruder mass becomes relevant when the voltage is reduced. Simulation of the complete system also showed that electrical and mechanical components can be integrated in one model, although the behavior of components of one domain can restrict the simulation performance of the entire system
Monte Carlo Study of Critical Relaxation near a Surface
No full textKikuchi M., Okabe Y.. Monte Carlo Study of Critical Relaxation near a Surface. Physical Review Letters 55, 1220 (1985); https://doi.org/10.1103/PhysRevLett.55.1220.We report the first Monte Carlo simulation on the critical relaxation of the three-dimensional kinetic Ising model with free surfaces. The surface-layer magnetization is shown to relax as t-1z at T=Tc, while the bulk magnetization relaxes as t-z. The dynamic bulk-to-surface crossover is discussed in view of the dynamic scaling theory
Exchange Rate Changes and the Trade Balance：Derivation of Generalized Marshall-Lerner Condition
No full textIn international economics, it has been well-known that when a nation’s currency appreciates (depreciates) the international trade balance decreases (increases), provided that import and export price-elasticities satisfy the so-called Marshall-Lerner (M-L) condition. This paper analyses the case in a more general setting and derives a “generalized M-L condition”, and shows that it includes the conventional M-L condition as a special case, as shown in Table 1 (on page 8, which appeared originally in Okabe 1986). The analysis also reveals that home country’s (Japanese) trade balance needs to be expressed not in foreign currency (dollar) but in home currency (yen) to effectively capture the external adjustment process. After this requirement was officially recognized, the authorities began in 1987 to publish the statistics of Japanese international trade and finance in both dollar and yen, and after 1996 only in yen.【Research Note】othe
Dynamic Analysis of a 3D Printer Based on the Delta Mechanism
No full textThis work presents the computational modeling and dynamic analysis of a three dimensional printer based on a delta mechanism using the multidisciplinary open source software MBDyn. Three dimensional printers can make complex parts with a minimum waste of material. These printers are usually slower than conventional methods of fabrication like milling. To overcome this problem, different types of mechanism such as Delta and SCARA have been tested in open source 3D printers. They are faster and have less components than cartesian mechanisms, but they demand a inverse kinematic analysis to translate G-code to printer motion. The printing process requires several steps from the computer modeling of the part to the 3d printing. A set of Python scripts and MBDyn analyses were used to mimic this process and to provide the dynamic behavior of the complete model of the printer. To understand the impact of the flexibility of the parallel arms in the printing process, three materials were tested: ABS plastic, aluminum and steel. Besides the arm's material, another element that influences the printer performance is the stepper motor, thus different microstepping strategies were simulated. The dynamic analysis showed that the flexibility of the parallel arms plays an important role in the positioning error of the deposition head. Plastic arms are cheap and easy to build, however, their deformation is excessive in high speed displacements. The microstepping analysis revealed that the ratio between carriage displacement and motor step is more important than the microstepping strategy
Extension of Mononobe-Okabe approach to unstable slopes
No full textThe resultant force of lateral earth pressures is commonly used in design of nearly vertical walls while flatter slopes are designed to be internally stable using a factor of safety approach. An unstable slope is considered to have unsatisfactory factor of safety unless supported by internal and/or external measures. However, from analytical viewpoint, the distinction between walls and unstable slopes is unnecessary. Using limit equilibrium analysis combined with a log spiral surface, a previous formulation is extended to deal with pseudostatic instability of simple, homogenous, cohesionless slopes. Hence, the original approach by Mononobe-Okabe (M-O) is extended to yield the resultant lateral force needed to stabilize an unstable slope. Given the slope angle, the design internal angle of friction, the backslope, the surcharge, the vertical and horizontal seismic acceleration, and the inclination of the resultant force, one can calculate the magnitude of this resultant. The approach allows for the selection of a rational inclination of the resultant for cases where soil-face interaction is likely to develop along vertical segments only. The approach generalizes the Coulomb (static) and the M-O (pseudostatic) methods as all are in the same framework of limit equilibrium. While all methods yield identical results for vertical slopes, where the critical slip surface defining the active wedge degenerates to the same planar surface, the presented approach becomes more critical for flatter unstable slopes where the active wedge is augmented by a curved surface. Hence, seamless extension of the M-O approach is produced.Leshchinsky, DovM.C.E.University of Delaware, Department of Civil and Environmental Engineerin
Uropsilus fansipanensis Bui & Okabe & Le & Nguyen & Motokawa 2023, sp. nov.
No full text<i>Uropsilus fansipanensis</i> sp. nov. <p>urn:lsid:zoobank.org:act: 6C15FBA6-D73B-44A0-A72F-0C326F92EB51</p> <p> <b>Holotype.</b> IEBR-M-8101 (field number Motokawa 837), an adult male, from Mount Fansipan, Hoang Lien National Park, close to the 2900-m camping station (22°18.804 N and 103°45.92 E), Lao Cai Province, Vietnam collected by Masaharu Motokawa on May 1, 2022, deposited in the Department of Vertebrate Zoology, Institute of Ecology and Biological Resources (IEBR), Vietnam Academy of Science and Technology, Hanoi. Skull was extracted. The body was preserved in 70% ethanol as a wet specimen.</p> <p> <b>Paratype.</b> IEBR-M-8102 (field number Motokawa 914), an adult male, from Mt. Fansipan, Hoang Lien National Park, along the Tram Ton–Fansipan peak trail (22°18.783 N and 103°45.92 E), Lao Cai Province, Vietnam, collected by Shinya Okabe on May 5, 2022, deposited in the IEBR. Skull was extracted. The body was preserved in 70% ethanol as a wet specimen.</p> <p> <b>Diagnosis.</b> Medium-sized shrew mole. Body bicolor, dorsum lightly reddish-brown and venter dark gray, but the separation between the dorsum and venter is not obvious. The tip of the fur on the back reddish-brown, and the rest is gray. The tail uniformly dark gray, long, slender, and covered with small scales arranged in rings; gradually darken from base to tip. Short bristle hairs sparsely covering the tail from the base to the tip, and longer at the tip of the tail. The mastoid process developed sideways and pointed out. The interorbital region broad and parallel. The zygomatic arch stouter. The foramen magnum very large. The lacrimal foramen well developed and much larger than the infraorbital foramen. The orbital process oriented upwards anteroposteriorly. Dental formula I 2/1, C 1/1, P 4/4, M 3/3 = 38 including teeth of I1, I2, C1, P1, P2, P3, P4, M1, M2, M3 / i2, c1, p1, p2, p3, p4, m1, m2, m 3 in the dentition. The buccal view of the upper fourth premolar (P4) triangular shape. The lower third premolar (p3) large in size. The lower first and third premolars (p1 and p3, respectively) approximately the same size. The lower canine (c1) larger than p1.</p> <p> <b>Description of holotype</b>. Adult male, medium-sized shrew mole with a total length of 140.0 mm and a body mass of 8.0 g (Fig. 2). The reddish-brown dorsal pelage distinct from the dark gray ventral pelage. The tail dark gray, its length (62.5 mm) slightly more than 80% of the head-body length (77.5 mm). Nose elongated with nostrils facing outwards; snout bicolored, upper part dark gray and lower part yellowish. The pinna protrudes (E 8.51 mm) covered by sparse gray hair. Limbs covered with scales down to the toes with long, sharp, and opaque claws; forefoot short but fat (FF1 = 8.66 mm, FF2 = 9.66 mm); hindfoot long and slender (HF1 = 13.41 mm, HF2 = 15.16 mm), and the four limbs have the same color as the tail, with small black speckled scales. The small eyes, barely noticeable under the fur.</p> <p>The skull (Fig. 3) long, and pyriform shaped with a short rostrum and a rounded braincase; palate relatively broad and possessing a sudden edge at the posterior end; pterygoid region deeply set; temporal ridges recognizable and converge in an X-shape; squamosal arm of the zygomatic arch sturdy; orbit locating at the midpoint of the skull; squamous processes sharp; bullae incomplete; pterygoid processes pointed saw-shaped; lacrimal foramen well developed and much larger than the infraorbital foramen; orbital process oriented upwards anteroposteriorly (Fig. 4). The mandible long and slender; coronoid process sharp and rear-facing crest; masseteric fossa arachnoid. Dental formula I 2/1, C 1/1, P 4/4, M 3/3 = 38 including teeth of I1, I2, C1, P1, P2, P3, P4, M1, M2, M3 / i2, c1, p1, p2, p3, p4, m1, m2, m 3 in the dentition (Fig. 3). The upper first incisor (I1) taller than the second incisor (I2); both I1 and I2 lingually concave; the upper canine (C1) slightly larger than the upper first premolar (P1); the upper third premolar (P3) small and the smallest tooth in the upper tooth row. The remaining upper premolars are shown from larger size to smaller size in the following order: upper fourth premolar (P4), upper second premolar (P2), and P1. The upper first molar (M1) larger than the upper second molar (M2); length and width of M1 are almost equal, and the same was observed in M2. The lower first incisor absent; the lower first and third premolars (p1 and p3, respectively) approximately the same size; the lower canine (c1) larger than p1; the lower second molar (m2) possesses a large concavity on its lingual side and protoconids from m2 is the highest cusp in the lower toothrow.</p> <p> <b>Variation.</b> The discoloration of the scales at the base of the tail showed substantial variation between the holotype and the paratype; the latter is strongly discolored. This is probably because the paratype is older than the holotype.</p> <p> <b>Etymology.</b> The specific epithet “ <i>fansipanensis</i> ” refers to the type locality of the new species, Mt. Fansipan. We suggest “Fansipan shrew mole” and “Chuột chũi vòi phan-xi-pan” for the common names in English and Vietnamese, respectively.</p> <p> <b>Ecological notes.</b> <i>U. fansipanensis</i> was found in a dwarf mountain forest on Mt. Fansipan, at an elevation of approximately 2800–2900 m. The surrounding habitat was grassy with shrubs on a thick and moist humus layer close to a small bamboo forest and a travel trail. During the field survey in May, which corresponds to the end of spring in northern Vietnam, the daily temperature fluctuates from 1 to 20°C, and sometimes rain occurs (Fig. 5A).</p> <p> <b>Distribution.</b> <i>U. fansipanensis</i> is presently known only from the type locality in Mt. Fansipan, Hoang Lien National Park, Lao Cai Province, northwestern Vietnam (Figs. 5B, 6).</p> <p> <b>Comparisons</b> (measurements are in mm). All members of <i>Uropsilus</i> have a primary coloration of brown dorsal and gray ventral fur, while they differ in terms of their tail color. <i>U. fansipanensis</i>, <i>U. soricipes</i>, <i>U. gracilis</i>, <i>U. andersoni</i>, and <i>U. atronates</i> have a uniformly colored tail. On the other hand, <i>U. investigator</i>, <i>U. nivatus</i>, <i>U. aequodonenia</i>, and <i>U. dabieshanensis</i> have a bicolor tail, with the upper part being darker than the underside (Table 2; Liu <i>et al</i>. 2013; Wan 2015; Hu <i>et al</i>. 2021).</p> <p> <i>U. fansipanensis</i> overlaps basic external morphological measurements with most of the other species of <i>Uropsilus</i> (Table 3). Nevertheless, it has a longer tail (T: 61.0–62.5) and hindfoot (HF: 13.41–13.57) than <i>U. dabieshanensis</i> (T: 52.4–54.1, HF: 12.8–12.9), and a shorter tail than <i>U. aequodonenia</i> (T: 67–73).</p> <p> <i>U. fansipanensis</i> shows overlap in most cranial measurements (Table 4) with <i>U. soricipes</i>, <i>U. nivatus,</i> and <i>U. atronates</i>, except a slightly larger anterior labial margin of the second upper molars than <i>U. nivatus</i> and <i>U. atronates</i> (M2-M2: 6.36–6.40 <i>vs.</i> 6.15–6.35 <i>vs.</i> 5.95–6.3). Nevertheless, it can be distinguished in several cranial measurements from the other five <i>Uropsilus</i> species as detailed below. <i>U. fansipanensis</i> has smaller upper toothrow length (UTRL: 9.03–9.07 <i>vs.</i> 9.1–10.7), palatal length (MPL: 9.62–9.75 <i>vs.</i> 9.68–11.2), lower toothrow length (MTRL: 8.30–8.31 <i>vs.</i> 8.43–9.09), mandible length (LM: 13.52–13.77 <i>vs.</i> 14.01–15.00), and braincase height (BH: 6.90–6.91 <i>vs.</i> 7.18–7.6) than <i>U. gracilis</i>.</p> <p> <i>U. fansipanensis</i> has a slightly wider snout (GBSn: 7.39–7.62 <i>vs.</i> 7.13–7.35) and longer mandible length (LM: 13.52–13.77 <i>vs.</i> 11.95–13.42) than <i>U. investigator</i>, while it has a shorter upper toothrow length (UTRL: 9.03–9.07 <i>vs.</i> 9.10–9.80).</p> <p>* The original source did not distinguish between HF1 and HF2.</p> <p> <i>U. fansipanensis</i> has a shorter profile length (PL: 20.4–20.69 <i>vs.</i> 20.65–22.28), shorter upper (UTRL: 9.03–9.07 <i>vs.</i> 9.25–9.95) and lower (MTRL: 8.30–8.31 <i>vs.</i> 8.49–9.07) toothrow length than <i>U. andersoni</i>.</p> <p> <i>U. fansipanensis</i> has a shorter profile length (PL: 20.4–20.69 <i>vs.</i> 20.75–22.03), basal length (BL: 16.62–16.98 <i>vs.</i> 16.70–17.86), and palatal length (MPL: 9.62–9.75 <i>vs.</i> 9.80–10.31) than <i>U. aequodonenia</i>.</p> <p> <i>U. fansipanensis</i> has a shorter profile length (PL: 20.4–20.69 <i>vs.</i> 21.11–21.76), shorter basal length (BL: 16.62– 16.98 <i>vs.</i> 17.59–17.98), shorter palatal length (MPL: 9.62–9.75 <i>vs.</i> 10.08–10.32), shorter mandible length (LM: 13.52–13.77 <i>vs.</i> 14.47–15.09), shorter lower toothrow length (MTRL: 8.30–8.31 <i>vs.</i> 8.40–8.79), a narrower snout (GBSn: 7.39–7.62 <i>vs.</i> 7.94–8.78), narrower greatest width across the upper second molars (M2-M2: 6.36–6.40 <i>vs.</i> 6.85–7.04), and higher braincase height (BH: 6.90–6.91 <i>vs.</i> 6.57–6.84) than <i>U. dabieshanensis</i>.</p> <p> Moreover, <i>U. fansipanensis</i> is distinguishable from all other <i>Uropsilus</i> species by the orientation of its orbital process (Fig. 4; Table 2). Specifically, the orbital process in <i>U. fansipanensis</i> is oriented upwards posteriorly, whereas in the other eight species, it is oriented downwards (Fig. 4). Lacrimal foramen and infraorbital foramen are separated by the orbital process, and the development of lacrimal foramen is an important morphological character distinguishing the genus <i>Uropsilus</i> from other genera of the family Talpidae (Hutchison 1968; Motokawa 2004). <i>U. fansipanensis</i> has a well-developed lacrimal foramen much larger than the infraorbital foramen, whereas the other eight species have lacrimal foramen smaller or similar in size to the infraorbital foramen (Fig. 4).</p> <p> <i>U. fansipanensis</i> has 38 teeth in total, similar to <i>U. gracilis</i>, <i>U. investigator, U. nivatus, U. atronates,</i> and <i>U. dabieshanensis</i> in lacking i3, while different from <i>U. soricipes</i> (34 teeth, it lacks P3, i3, and p3), <i>U. aequodonenia</i> (36 teeth, it lacks P3 and p3), and <i>U. andersoni</i> (38 teeth, it lacks p3) (Table 2; see Thomas 1912). <i>U. fansipanensis</i> is characterized by the size of p3, which is well-developed and approximately equal to the lower first premolar (p1). In contrast, p3 is smaller than p 1 in <i>U. gracilis</i>, <i>U. investigator</i>, <i>U. nivatus</i>, <i>U. atronates</i>, and <i>U. dabieshanensis</i> (Table 2). Additionally, <i>U. fansipanensis</i> is distinguished from <i>U. gracilis</i> and <i>U. atronates</i> by having c1 larger than p1, while these characteristics are shared with the remaining six species (Table 2; Allen 1923).</p>Published as part of <i>Bui, Hai Tuan, Okabe, Shinya, Le, Linh Tu Hoang, Nguyen, Ngan Thi & Motokawa, Masaharu, 2023, A new shrew mole species of the genus Uropsilus (Eulipotyphla: Talpidae) from northwestern Vietnam, pp. 59-78 in Zootaxa 5339 (1)</i> on pages 62-70, DOI: 10.11646/zootaxa.5339.1.3, <a href="http://zenodo.org/record/8290254">http://zenodo.org/record/8290254</a>
The mechanics clarifying counterclockwise rotation in most IVF eggs in mice
No full textIshimoto, K., Ikawa, M. & Okabe, M. The mechanics clarifying counterclockwise rotation in most IVF eggs in mice. Sci Rep 7, 43456 (2017). https://doi.org/10.1038/srep43456In mammalian fertilization, a small spermatozoon interacts with an egg that is a few thousand times larger in volume. In spite of the big difference in size and mass, when spermatozoa are bound to eggs, they begin rotating the eggs in in vitro observation. This was dubbed the 'fertilization dance'. Interestingly, some papers reported that the rotation was counterclockwise, although the reason for this skewed rotation was not clarified. We focused on a chirality of helical beating of spermatozoa and found that eggs rotate counterclockwise in simulations under a certain geometrical condition where the eggs were situated. This theory of egg rotation was validated by demonstrating egg rotation in a clockwise direction by floating eggs to the upper surface of the IVF medium. The enigma of skewed rotation of IVF eggs was clarified
How Can Economics be Humanized by Integrating Altruism?
No full textOver the past century, science and technology have marvelously brought about a pleasant life to many people on the globe. On the other hand, mankind is still facing many serious and unsolved problems, such as international disputes and terrorism, expanding inequality of economic welfare, global warming, and effective control of artificial intelligence, to name a few.
In order to solve these problems, an innovative international research project has recently been proposed which asserts a new value of “self-examination and altruism” (自省利他) as a key to human behavior. It does not simply assume that man is a selfish existence but assumes that man naturally have an altruistic motive (利他), so that self-examination (自省) becomes important to reveal that aspect of human nature. This international research project intends to utilize the knowledge not only of humanities but also of social and natural sciences, and try to access the viability of the concept of “self-examination and altruism” as a new principle of democracy.
The research group, coordinated by Dr Hideaki Nakatani of Ryukoku University in Kyoto, consists of about ten Japanese and overseas researchers including a Harvard University researcher. The project is expected to extend for two to five years. The author (Okabe) has been invited to participate in this project and submitted his research proposal hereby attached.【International Research Proposal】othe
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