市場効率性の測定 : タイム･ディフォルメーション･モデルの適用

経博(経営

Durability performance of frp strenghtened concrete beams and columns exposed to hygrothermal environment

ABSTRACT DURABILITY PERFORMANCE OF FRP STRENGHTENED CONCRETE BEAMS AND COLUMNS EXPOSED TO HYGROTHERMAL ENVIRONMENT by ABULGASEM M. ELARBI August 2011 Advisor: Dr. Hwai-Chaung Wu Major: Civil and Environmental Engineering (Structural Engineering) Degree: Doctor of Philosophy Concrete structures deteriorate over time due to exposure to various environments, including hot and humid weather. High temperature, wind, and air humidity in many hot climates can all have a negative impact on the performance of concrete structures. The most important factors are temperature and humidity - often times these effects are not immediately evident and develop years later - making determination of responsibility difficult and repair expensive.Fiber reinforced polymer (FRP) composites have been recognized as a viable material for strengthening/retrofitting deficient structures, due to their superior performance. FRP sheets/fabrics are usually bonded to existing reinforced concrete structures. Due to their high specific strength/stiffness and lightweight, these materials can offer significant advantages over more traditional materials such as concrete and steel. The present investigation intends to study the effects of changing hygrothermal conditioning cycles (either by changing relative humidity and temperature is kept constant, or by changing temperature but relative humidity is maintained same) on the durability performance of FRP strengthened concrete beams and columns. The study include the long term influence of moisture, high temperature, and combined hygrothermal conditions on the mechanical properties of FRPs composites and the effect of deteriorated composites on the structural behavior of concrete beams and columns when subjected to realistic environmental conditions. This study includes also the study of the fracture behavior between concrete and external FRP strips in hygrothermal condition. The overall approach consists of experiments, analysis, and computations. An extensive experimental research has been done throughout implement and test several sets of specimens include epoxy beams, concrete beams and columns, and FRP strengthened concrete beams and columns exposed to different environmental conditions. Carbon and glass fiber reinforcement polymer with resin material were provided from two different resources have been utilized in this study. Also, two and three-dimensional extended finite element method (X-FEM) is developed and implemented in the ABAQUS-CAE package to predict the bond strength at the interface between concrete and FRP strengthening fabric. In addition, analytical calculations for epoxy beams, non-strengthened concrete beams, and columns, FRP strengthened beams and columns were developed based on the ACI 318 and ACI 440.2R-02 including the environmental effects based on the temperature dependent factor

Effect of Aging Time and Boron Addition on the Properties of 9-12% Cr Power Plant Steels - outcomes from Different Experimental Investigations

The relation between the aging time and the mechanical properties of the investigated steels was demonstrated graphically as a result of an experimental work in this paper. The effect of trace boron in steels, especially the influence of boron on microstructure and properties of 9-12% Cr steels were also summarized. Three alloys with and without boron of 9% Cr steels were prepared. The specimens prepared for testing were aged at 20 oC and 650 oC for time range of 3000 to 10000 hrs. Concerning the effect of boron addition to the 9-12% Cr steels, some results of recent investigation studies by other researchers were also mentioned in this paper for more information about the role of this alloying element in improving of high alloyed chromium steels

Contributions of different factors to the improvement of the creep rupture strength of creep resistant martensitic steels

Boilers, pipes, and turbine components of fossil power generating plants are expected to be exposed to steam at increased temperature and pressure to improve power generating efficiency. This trend requires high Cr creep resistant martensitic steels having higher creep rupture strength (CRS) than Modified 9Cr-1Mo steel. The aim of this paper is to overview different factors that improve the creep rupture strength of these required new steels. The addition of W, B, Co, Cu and other elements to the 9-12 % Cr steels which has been studied by many researches to improve CRS is explained. Improvement of the method of heat treatment that has been investigated by other investigators is introduced as well. It has been reported that CRS can be raised by optimizing the normalizing temperature, controlling the cooling rate from normalization temperature before tempering, or by applying the thermo-mechanical control process (TMCP). By the application of TMCP process, a great increase in the CRS can be obtained

Generic Model for Mobile Tourists Guide System (GMMTGS)

Nowadays, information discovery becomes more relevant to peoples' lifestyle with the implementation of mobile technology. In different ways, people can gather information they need just about anywhere without having to be physically connected to the Internet. With the support of Wireless Application Protocol (WAP), the development of mobile application turns to be realistic and reliable as it follows the correct protocol. This study has developed and designed a generic mobile tourist system based on tourists' requirements. The study used the JSP language and MYSQL server for the system development. Furthermore, the proposed system was tested using use test case with five students. Finally, the proposed generic mobile tourists guide system aims to satisfy tourist needs

Preference fusion and Condorcet's Paradox under uncertainty

Facing an unknown situation, a person may not be able to firmly elicit his/her preferences over different alternatives, so he/she tends to express uncertain preferences. Given a community of different persons expressing their preferences over certain alternatives under uncertainty, to get a collective representative opinion of the whole community, a preference fusion process is required. The aim of this work is to propose a preference fusion method that copes with uncertainty and escape from the Condorcet paradox. To model preferences under uncertainty, we propose to develop a model of preferences based on belief function theory that accurately describes and captures the uncertainty associated with individual or collective preferences. This work improves and extends the previous results. This work improves and extends the contribution presented in a previous work. The benefits of our contribution are twofold. On the one hand, we propose a qualitative and expressive preference modeling strategy based on belief-function theory which scales better with the number of sources. On the other hand, we propose an incremental distance-based algorithm (using Jousselme distance) for the construction of the collective preference order to avoid the Condorcet Paradox.Comment: International Conference on Information Fusion, Jul 2017, Xi'an, Chin