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Flexural Properties of Damaged RC Beams Subjected to Axial Compression in the Vertical Direction
Get PDFThe longevity of social infrastructure is a societal need, and various reinforcement techniques have been proposed for concrete structures. The authors propose a reinforcement technique where bolts are inserted vertically into sound beams and tightened with nuts to apply compressive force. Results from bending tests indicate an expected improvement in ductility. This study applies the proposed method to RC beams with damage and examines its bending behavior. Reinforcing the damaged area with the proposed method confirms an increase in vertical displacement but a decrease in stiffness. Reinforcement at a distance from the damaged area does not increase vertical displacement, yet slightly enhances load-bearing capacity.departmental bulletin pape
What was Newton's Word "hypotheses non fingo"? ―History of its Generation and its Translation―
Get PDFNewton's "Hypotheses non fingo" is one of the most famous and influential words which he used. Its English or other languages translations are various. In this paper, I try to give the proper English and Japanese translation through examining the process of generation of this word. Unlike previous studies, I argue that Newton was not initially conscious that this word must be translated as "I do not feign hypotheses" (most known translation today). Rather, Newton had getting to intend to include pejorative meaning into this word in order to clarify the difference of his philosophical methodology from Leibniz's one. As a result, the English translation "I do not feign hypotheses" became authoritative translation after establishing his philosophical position (1716 at the earliest) although he was unconscious it at the time he wrote this word in the second edition of the "Principia" (1713).departmental bulletin pape
Sintering aids for manufacture of hot-pressed TiB2-B4C composite ceramics
Get PDFTo search the effective sintering aids for (TiB2)0.6(B4C)0.4 composite ceramics, the ceramic compacts were hot-pressed at 1950℃ (some 1750, 1650℃) for 1 hour under 28.2 MPa with 6 mol% each of SiC, AlN, Si3N4, TiN and Y2O3 sintering aids. The effects of sintering aids on mechanical and electrical properties were investigated.
As a result, when AlN sintering aid was used (sintering temperature 1750℃), bending strength was improved to 1.20 times (723MPa) and fracture toughness was greatly improved to 1.66 times (8.67MPa･m1/2) compared to the case without aids. In the case of SiC aid, the overall properties improved.departmental bulletin pape
Fundamental study of YAG laser processing of various ceramics
Get PDFIn this study, YAG laser beams with energies of about 3.8 J/shot for cutting and 6.05 J/shot for welding were applied to various ceramics such as oxides, nitrides, carbides, borides and their composites. The possibility of laser processing for ceramics and the ceramics suitable for cutting and welding were investigated with one shot irradiation.
As a result, the ceramics considered to be suitable for laser processing (cutting and welding) are PLS(pressureless sintering)-TiO2, HP(hot-press)-TiB2-B4C system, HP-TiN-B4C system and PLS-Si3N4. Otherwise, HP and PLS-TiB2-ZrB2 systems are considered unsuitable ceramics.departmental bulletin pape
Mechanical and electrical properties of TiB2-TiC composite ceramics by spark plasma sintering
Get PDFTiB2-TiC ceramic composites containing 0 up to 100 mol%TiC (20mol%steps) were fabricated from a mixture of TiB2 and TiC powders by spark plasma sintering(SPS) method, and properties of those materials were investigated.
The derived TiB2-TiC composite containing 20～80mol%TiC have high properties: a relative density of 97.5～99.6%, Vickers hardness of 20.4～21.4 GPa, flexural strength of 476～575 MPa, fracture toughness (KIC) of 6.01～7.15 MPa･ｍ1/2, Young's modulus of 475～561 GPa, and electrical conductivity of 2.28～6.53 MS/m.
The composites present high mechanical properties compared with those for TiB2 or TiC single phase. The composites are suitable as ceramic mold materials machinable by electric discharge.departmental bulletin pape
Fundamental Analysis on the Possibility of Change in Transportation Mode Selection by Providing Information -For Zenkoji Gokaicho in Nagano City-
Get PDFIn 2022, the Zenkoji Temple Gokaicho was held in Nagano City. Since many tourists are expected to visit the temple from all over Japan, traffic congestion is expected to occur around Zenkoji Temple and the city center. In this study, based on the questionnaire survey on traffic congestion countermeasures for visitors, the decision-making information on the use of each means of transportation was clarified, and the logistic regression analysis model was used to clarify the important information that influences. In addition, we will examine the acceptability of introducing MaaS as a new service to promote the use of public transportation.departmental bulletin pape
Mechanical and electrical properties of pure TiN ceramics by pressureless sintering －Effects of mold pressure and Ar atmosphere pressure－
Get PDFThe mechanical and electrical properties of pure TiN ceramics produced by the pressureless sintering method were investigated. In the experiment, the powder was molded at 50-400 MPa, and then sintered at 2100°C with 60 minutes in Ar atmosphere of 1.2atm, and was molded at 100MPa and then sintered at 1950℃ with 60 minutes in an Ar atmosphere of 0-10atm. In the case of pressureless sintering of pure TiN, the property improvement is slight even if the mold compacting pressure is increased. Mold compacting pressure of about 100 MPa is sufficient. The improvement in the characteristics is small even if the Ar atmosphere pressure is increased. The Ar gas pressure of about 1.2 atm is sufficient. When sintered in a vacuum, there is a possibility that the composition will deviate from the stoichiometric composition, but it often exhibits unique properties and may be useful.departmental bulletin pape