103 research outputs found

    Modeling of Root-reinforced Soil Slope under Rainfall Condition

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    This paper presents the results of geotechnical centrifuge and numerical modeling study of root-reinforced systems on soil slopes. The centrifuge models were designed to simulate a soil slope reinforced by vetiver grass root system commonly grows in Southeast Asian countries. Unreinforced and root-reinforced soil slope models were subjected to heavy rainfall using a rainfall simulator designed for a geotechnical centrifuge. Results of the study show that the root system causes a reduction of rainwater infiltration rate, delay in the response of groundwater table, and increasing in soil shear strength. The results were validated by comparing centrifuge modeling test results with numerical modeling analyses based on limit equilibrium and finite element methods. The transient seepage analysis results were employed in the slope stability analysis. The numerical analysis shows a good agreement in failure mechanisms with the observations from centrifuge modeling tests.This paper presents the results of geotechnical centrifuge and numerical modeling study of root-reinforced systems on soil slopes. The centrifuge models were designed to simulate a soil slope reinforced by vetiver grass root system commonly grows in Southeast Asian countries. Unreinforced and root-reinforced soil slope models were subjected to heavy rainfall using a rainfall simulator designed for a geotechnical centrifuge. Results of the study show that the root system causes a reduction of rainwater infiltration rate, delay in the response of groundwater table, and increasing in soil shear strength. The results were validated by comparing centrifuge modeling test results with numerical modeling analyses based on limit equilibrium and finite element methods. The transient seepage analysis results were employed in the slope stability analysis. The numerical analysis shows a good agreement in failure mechanisms with the observations from centrifuge modeling tests

    カンボジアの大学1年生の学力に関する断層線型モデルを用いた研究

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    広島大学(Hiroshima University)博士(学術)Philosophydoctora

    Dynamic Link from Liftoff to Final Orbital Insertion for a MEO Space Vehicle

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    During the entire launch sequences from liftoff to final orbital insertion of a space vehicle (SV), adequate link requirements are to be maintained for telemetry, tracking, and command (TT&C) for uplink and downlink services, from launch vehicle (LV) and SV to ground stations (GS). A successful space vehicle launch required adequate link coverage with good radio frequency (RF) performance. The chapter is an extension of the IEEE/Aerospace Conference 2019 paper entitled Dynamic Link Analysis and Application for a MEO Space Vehicle published by the authors. The emphasis in this chapter is on the addition of the three distinctively different tracking waveforms and their associated links, used from liftoff to final orbital insertion. This chapter will describe the three required dynamic link analyses (DLA) to cover (a) the LV link from liftoff to its end of line of sight (LOS), (b) the LV link from LOS to Tracking and Data Relay Satellite System (TDRSS) at beyond line of sight (BLOS), and (c) the final tracking link using Space-to-Ground Link Subsystem (SGLS) or non-SGLS (NSGLS) link for the earliest or best separation time of the SV from the LV. The chapter discusses the concept of the dynamic link analysis, SV antenna switching schedule, recommended SV separation time, as well as the performance for different launch scenarios within the 24-h launch window. Topics include antenna patterns, launch trajectories, elevation angle and clock and cone angle geometry, and dynamic link budget

    Ontology-Based Multiplatform Identification Method

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    This paper puts forward a multiplatform identification method to overcome the limitations of a single platform strategy when mass customization is required. The method is applied to redesign or consolidate an existing product family. The method consists of four steps: (1) the determination of component values, (2) the estimation of component redesign efforts, (3) the platform component identification, and (4) the formation of multiple platform instances. An ontology-based framework is also provided to facilitate the information representation and the data integration in the identification of multiplatform structure. Once the platforms are identified, an ontology reasoning mechanism verifies the platform sharing among products and determines the possible multiplatform coalition. A water cooler product family is used to illustrate the ontology-based multiplatform identification method

    ‘Real-world’ health care priority setting using explicit decision criteria: a systematic review of the literature

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    BACKGROUND: Health care decision making requires making resource allocation decisions among programs, services, and technologies that all compete for a finite resource pool. Methods of priority setting that use explicitly defined criteria can aid health care decision makers in arriving at funding decisions in a transparent and systematic way. The purpose of this paper is to review the published literature and examine the use of criteria-based methods in ‘real-world’ health care allocation decisions. METHODS: A systematic review of the published literature was conducted to find examples of ‘real-world’ priority setting exercises that used explicit criteria to guide decision-making. RESULTS: We found thirty-three examples in the peer-reviewed and grey literature, using a variety of methods and criteria. Program effectiveness, equity, affordability, cost-effectiveness, and the number of beneficiaries emerged as the most frequently-used decision criteria. The relative importance of criteria in the ‘real-world’ trials differed from the frequency in preference elicitation exercises. Neither the decision-making method used, nor the relative economic strength of the country in which the exercise took place, appeared to have a strong effect on the type of criteria chosen. CONCLUSIONS: Health care decisions are made based on criteria related both to the health need of the population and the organizational context of the decision. Following issues related to effectiveness and affordability, ethical issues such as equity and accessibility are commonly identified as important criteria in health care resource allocation decisions. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12913-015-0814-3) contains supplementary material, which is available to authorized users

    Factors influencing college students’ academic achievement in Cambodia: a case study

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    The purpose of this study is to address achievement gaps among Cambodian students attending an English higher education institution in Cambodia by exploring factors that contribute to their academic achievement. Using a hierarchical multiple regression on second-year students (N=215) and teachers (N=23), this study examined the relative influence of student engagement behaviors, students’ background characteristics, and teacher quality on students’ academic achievement. Both general and interaction effects by students’ geographical origins were examined. The results suggested a variety of factors that positively predicted student achievement: the importance of students investing more efforts in homework or given tasks and whole-class participation, students’ pre-college academic experience, teachers’ teaching experience and course workload and difficulty. Interaction effect existed between students’ pre-college academic experience and geographical origins. With these findings, some important implications for closing student achievement gaps are discussed
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