19 research outputs found
Practice of Distance Learning of Physical Education for Children during COVID-19 Pandemic
No full textdepartmental bulletin pape
Aerodynamic design applying automatic differentiation and using robust variable fidelity optimization
No full textIn modern aerospace engineering, the physics-based computational design method is becoming more important. However, high-fidelity models require longer computational time, so the advantage of efficiency is partially lost. This problem has been overcome with the development of the approximation management framework (AMF).
In the AMF, objective and constraint functions of a low-fidelity model are scaled at a design point so that the scaled functions, referred to as gsurrogate functions, h match those of a high-fidelity model. Since scaling functions and the low-fidelity model constitutes surrogate functions, evaluating the surrogate functions is faster than evaluating the high-fidelity model. Therefore, in the optimization process of the AMF, the surrogate functions are used to obtain a new design point.
However, the author found that 1) the AMF is very vulnerable when the computational analysis models have numerical noise, and that 2) the AMF terminates optimization prematurely when the optimization problems have constraints.
In order to solve the first problem, automatic differentiation (AD) technique is applied. If derivatives are computed with the generated derivative code, they are analytical, and the computational time is independent of the number of design variables. However, if analysis models implement iterative computations such as computational fluid dynamics (CFD), computing derivatives through the AD requires a massive memory size. The author solved this deficiency by modifying the AD approach and developing a more efficient implementation with CFD.
In order to solve the second problem, the governing equation of the trust region ratio is modified so that it can accept the violation of constraints within some tolerance. By accepting violations of constraints during the optimization process, the AMF can continue optimization without terminating immaturely and eventually find the true optimum design point.
With these modifications, the AMF is referred to as gRobust AMF, h and it is applied to airfoil and wing designs using Euler CFD software. The proposed AD method computes derivatives more accurately and faster than the finite differentiation method, and the Robust AMF successfully optimizes shapes of the airfoil and the wing in a much shorter time than the sequential quadratic programming with only high-fidelity models.Ph.D
A remarkable effect of the combination of probabilistic peer-punishment and coevolutionary mechanism on the evolution of cooperation
No full textAbstractIn the previous studies, the author has proposed the probabilistic peer-punishment based on the difference of payoff, and presented that the proposed peer-punishment utilizes its mechanism for preventing antisocial punishment like retaliation of a defector on a cooperator, effectively enhances the evolution of cooperation, and greatly increases the average payoff of all players in various parameters regarding static three types of topology of connections. Here, this study introduces both activities of breaking and creating connections of every player based on his/her preference to the model of the proposed peer-punishment. Every player will keep connections with his/her preferable players, whereas he/she will frequently break connections with his/her dissatisfied other players. Therefore, the new model of this study is the combination of probabilistic peer-punishment and coevolutionary mechanism that not only strategy of players but also connections between players evolve. This study discovers new knowledge that such combination induces high-level evolution of cooperation and great increase of the average payoff of all players in the condition where cooperation is hard to evolve.</jats:p
Reliability of a k-out-of-n System with Common-cause Failures Using Multivariate Exponential Distribution
No full textAbstractIn recent years, numerous papers dealing with extensions of Marshall-Olkin distributions have appeared. However, the Marshall- Olkin model is not yet a commonly used mathematical model in the field of risk analysis, even though it has been considered to be suitable for common cause analysis in the field of statistics. We consider the reliability of a k-out-of-n system subjected to Marshall-Olkin type shocks. All combinations of components in the system are assumed to be shock sources in the analysis. We formulate the system reliability and numerically compare the results with those obtained using the conventional α-factor model
A Thought on the Rebirth of "Traditional Japanese Culture" and the Amendment of the Fundamental Law of Education
No full textP(論文)Discussions concerning the amendment of the Fundamental Law of Education have been under active debate. One of the main issues is related to the confusion around the concept of "traditional Japanese culture". Is "traditional Japanese culture" equal to exclusive ultra-nationalism? Or can it play a potential role to create a new dimension for the future education in this country? This paper tries to explore the meaning of the concept of "traditional Japanese culture" from standpoints of the spirit of "the Way of Tea" (sado). The author emphasizes the importance of introduction an article to respect "traditional Japanese culture" into the new Fundamental Law of Education.departmental bulletin pape
Effect of polypropylene and steel fibers on web-shear resistance of deep concrete hollow-core slabs
No full textTwelve shear tests were conducted on fiber-reinforced precast/prestressed concrete hollow-core (PCHC) slabs to quantify the effectiveness of polypropylene (pp) and steel fibers (hooked and high-strength/straight types) on shear resistance. Different volume fractions of pp fibers (0.11 and 0.22%) and steel fibers (0.51 and 0.89%) were investigated. The experimental results showed that there were moderate increases in shear strength with the use of pp fibers while substantial increases in shear resistance were observed with the use of steel fibers. In addition, shear strength increased with steel-fiber content. Moreover, with the same steel fiber content of 0.89%, specimens with high-strength/straight fibers exhibited superior performance in shear resistance compared to specimens using hooked steel fibers. In addition, web-shear failure occurred in the majority of specimens. However, as steel fiber content was increased up to 0.89%, in some instances, failure mode shifted from web-shear to flexural-shear failure. In addition, the 2010 fib model code formula for shear strength of steel-fiber-reinforced-concrete (SFRC) members was used to estimate shear capacity of the tested slabs using steel fibers. The calculations showed that the fib model code was overly conservative for shear-strength predictions of SFRC hollow-core slabs reported in this investigation. A semi-empirical formula to calculate shear strength of hollow-core slabs with steel fibers was proposed. It was verified using a database including the 6 shear-test results from this study and another 39 shear-tests on SFRC hollow-core slabs compiled from literature. The formula had a mean value of 1.12 for the ratio of experimental shear strength to calculated shear strength with a coefficient of variation of 0.21.Ministry of National Development (MND)National Research Foundation (NRF)The support of the National University of Civil Engineering (NUCE), Vietnam for granting the first author a sabbatical leave to carry out this research at the Nanyang Technological University, Singapore is highly appreciated. The authors also wish to acknowledge the first author’s scholarship and the funding for testing from the Singapore Ministry of National Development and National Research Foundation under L2 NIC Award No. L2NICCFP1-2013-4
Purification and characterization of a chloride ion-dependent alpha-glucosidase from the midgut gland of Japanese scallop (Patinopecten yessoensis)
No full textMarine glycoside hydrolases hold enormous potential due to their habitat-related characteristics such as salt tolerance, barophilicity, and cold tolerance. We purified an -glucosidase (PYG) from the midgut gland of the Japanese scallop (Patinopecten yessoensis) and found that this enzyme has unique characteristics. The use of acarbose affinity chromatography during the purification was particularly effective, increasing the specific activity 570-fold. PYG is an interesting chloride ion-dependent enzyme. Chloride ion causes distinctive changes in its enzymatic properties, increasing its hydrolysis rate, changing the pH profile of its enzyme activity, shifting the range of its pH stability to the alkaline region, and raising its optimal temperature from 37 to 55 degrees C. Furthermore, chloride ion altered PYG's substrate specificity. PYG exhibited the highest V-max/K-m value toward maltooctaose in the absence of chloride ion and toward maltotriose in the presence of chloride ion
