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Project Progress Management under Resource Constraints and Uncertain Environmental Factors(資源制約と不確実な環境因子を考慮したプロジェクト進捗管理に関する研究)

氏名 Luong Duc Long
学位の種類 博士(工学)
学位記番号 博甲第431号
学位授与の日付 平成19年8月31日
学位論文題目 Project Progress Management under Resource Constraints and Uncertain Environmental Factors (資源制約と不確実な環境因子を考慮したプロジェクト進捗管理に関する研究)
論文審査委員
 主査 教授 大里 有生
 副査 教授 中村 和男
 副査 教授 浅井 達雄
 副査 教授 山田 耕一
 副査 准教授 五島 洋行

平成19(2007)年度博士論文題名一覧] [博士論文題名一覧]に戻る.

Abstract p.I
Contents p.II
List of figures p.VIII
List of tables p.X
Chapter 1. Introduction
 1.1 Introduction of project progress management p.2
 1.2 Project progress management under resource constraints and uncertainty p.3
 1.3 Practice of project progress management in VietNam p.7
 1.4 Problem description of project progress management under resource constraints and uncertain environmental factors p.10
 1.4.1 Problem 1- The project scheduling problem under effects of uncertain environmental factors p.10
 1.4.2 Problem 2- Project scheduling problem under effects of certain environmental factors p.10
 1.4.3 Problem 3- Problem of project controlling p.10
 1.5 Solution strategy for project progress management p.11
 1.5.1 Fuzzy theory for modeling uncertainty p.11
 1.5.2 Solution Strategy p.12
 1.5.3 General outline of the proposed method p.13
 1.6 Scope of the dissertation p.13
 1.7 Organization of the dissertation p.14
Chapter 2. An Overview of Project Progress Management
 2.1 Definitions of project,project management and project progress management p.17
 2.1.1 Definition of a project p.17
 2.1.2 Definition of a project managment p.18
 2.1.3 Project progress management p.19
 2.1.4 Project progress management in the project life cycle p.20
 2.2 Literature review of project scheduling under resource constraints p.21
 2.2.1 Resource constrained-project scheduling with project duration objective p.22
 2.2.2 Resource constrained-project scheduling with project net present objective p.24
 2.3 Literature review of project scheduling under uncertainty p.26
 2.3.1 Probability theory-based project scheduling p.26
 2.3.1.1 Probability theory-based project scheduling without using buffers p.26
 2.3.1.2 Probability theory-based project scheduling without using buffers p.29
 2.3.2 Fuzzy theory based project scheduling p.31
 2.3.3 Fuzzy resource-constrained project scheduling p.34
 2.4 Literature reviewof project progress control p.35
Chapter 3. Project Scheduling under Resource Constraints by Genetic Algorithm
 3.1 Introduction p.38
 3.1.1 Project scheduling under resources constraints p.38
 3.1.2 Project scheduling under resources constraints with variable activity durations(Problem 1) p.39
 3.2 Description of the resource-constrained project scheduling with variable activity duratons p.42
 3.2.1 Activity network p.42
 3.2.2 Mathematical description of the problem p.43
 3.3 Solution methodology p.47
 3.3.1 Main procedure(P1) p.47
 3.3.2 Sub-procedure(A19 p.50
 3.4 Illustrative examples p.54
 3.4.1 First example p.54
 3.4.2 Second example p.56
 3.4.3 Comparing the proposed method and other methods p.60
 3.5 Conclutions p.61
Chapter 4. Project Schedule Management Considering Uncertain Environmental Factors Using a Fazzy Activity Network
 4.1 Introduction p.64
 4.2 Fuzzy activity network under the effects of uncertain environmental factors p.66
 4.2.1 Fuzzy activity network p.66
 4.2.2 Fuzzy arithmetic for two fuzzy numbers p.68
 4.2.3 Fuzzy activity network under effects uncertain environmental factors p.69
 4.3 The proposed procedure(P2)for project scheduling under uncertain environmental factors p.70
 4.3.1 Component hierarchy in activity duration p.70
 4.3.2 Breakdown of uncertainty by factors p.70
 4.3.3 Breakdown of uncertainty by factor conditions p.73
 4.3.4 Outline of the procedure(P2) p.77
 4.3.5 Estimating path duration p.79
 4.3.6 Estimating project duration p.82
 4.3.7 Path sensitivity analysis p.83
 4.3.8 Compatibility estimation between project duration and expected duration p.84
 4.4 Illustrative example p.85
 4.5 Conclutions p.92
Chapter 5. Project Progress Management under Resource Constraints and Uncertain Environmental factors
 5.1 Introduction p.95
 5.1.1 Fuzzy set theory for modeling uncertainty p.96
 5.1.2 Critical chain concept p.96
 5.2 Detailed description of project progress management p.98
 5.2.1 Detailed description of resource constrained-project scheduling problem with variable activity durations p.98
 5.2.2 Problem description of project progress under uncertain environmental factors p.101
 5.2.3 Problems description of project controlling p.102
 5.3 Project progress management under resource constraints and uncertain environmental factors p.102
 5.3.1 Solution methodology p.102
 5.3.2 Dealing with resource constraints in project scheduling (Stage 1) p.103
 5.3.3 Dealing with uncertainties in project scheduling under resource constraints (Stage 2) p.103
 5.3.3.1 Strategy to deal with uncertainty p.103
 5.3.3.2 Project duration with high agreement index p.105
 Project buffer p.106
 5.3.3.4 Relationship between the project duration and the agreement index p.107
 5.3.4 Controlling the project peogress (Stage 3) p.107
 5.3.4.1 Revision of activity durations at he execution phase p.107
 5.3.4.1 Updating the planned schedule during execution phase p.109
 5.3.5 Outline of the proposed method p.109
 5.4 Numerical example p.110
 5.5 Conclusions p.119
Chapter 6. Concluding Remarks and Future Research
 6.1 Concluding remarks p.122
 6.2 Limitation of the proposed method p.124
 6.3 Future research p.124
List of Author's Publications p.125
Reference p.126
Appendix 1-Basic Concept of Fuzzy Set Theory p.134
Appendix 2-Basic Concept of Genetic Algorithm p.137

 This thesis focuses on the study on viscoelasticity of rubber materials in both linear and nonlinear regions.
 Organic softmaterials including rubber have been widely used. The biggest benefit of the soft materials can be found in good processability due to relatively low modulus and high deformability based on entropic elasticity. For industrial purpose, however, inorganic fillers are required to be mixed for reinforcement. In addition, polymeric materials have enormously wide distribution of relaxation time. The relaxation times vary too much depending on temperature. Therefore, one might consider that it is fairly difficult to treat viscoelasticity of filled rubbers in general fashion. For example, some investigators have reported shift factors in time-temperature superposition depend on kind of filler, but others have reported they do not depend on. However, it is well known that temperature dependence of polymer viscoelasticity is well expressed by simple WLF equation which does not depends on molecular weights, molecular weight distributions, and existence or nonexistence of entanglements, which suggests the temperature dependence of filled rubber viscoelasticity is fairly simple. The purpose of the thesis is to study the temperature dependence of viscoelasticity of filled-rubber by measuring dynamic modulus in wide range of temperature and frequency, and to make additional study on the origins of nonlinear viscoelasticity and its industrial application.
 In chapter 1, the background, the significance, and the purposes of the thesis have been described as the introduction. In addition, the points to be discussed on temperature dependent viscoelasticity of various filled rubbers, both cross-linked and uncross-linked, and on mechanisms of nonlinear viscoelasticity of polymers have been reviewed.
 In chapter 2, after the importance and the problems on time-temperature superposition procedures of filled rubbers are preliminarily discussed, the effects of existence or nonexistence of carbon black filler and cross-linking points on the glass transition temperature and shift factors have been discussed in terms of linear dynamic modulus measured in wide range of temperature and frequency. In addition, the results have been compared with the temperature dependence of the corresponding nonlinear viscoelasticity.
 In chapter 3, filler effects on temperature dependence of viscoelastic properties of filler rubbers have been discussed in a comprehensive way. The next two points have been found; a) the glass transition temperature increases with the introduction of cross-linking points, but does not depend on existence or nonexistence of filler and kinds of fillers, b) the temperature dependence of viscoelasticity of rubber materials can be expressed by a universal function of the difference between measured and reference temperatures irrespective of existence or nonexistence of cross-linking points, that of filler, and kinds of fillers, if we take the glass transition temperatures as the reference temperatures.
 In chapter 4, after change in entanglement density and anisotropic configuration of chain molecule are discussed preliminarily to be possible two origins of nonlinear viscoelasticity of well entangled polymers, the latter has been proved experimentally to be one of the corresponding origins.
 In chapter 5, it has been confirmed experimentally that process control of loss factor in rubber materials can be made by anisotropic chain configuration fixed on the basis of the new concept developed in the chapter 4.
 From the results above, it has been clarified that the temperature dependence of viscoelastic properties of filled rubber is determined by that of the matrix polymer, that is, filler does not change the time-scale but the magnitude of modulus. This means we are allowed to consider independently time-temperature correspondence effects and reinforcement effect in making simulation of processing by using viscoelasticity of filled rubber materials. The thesis has offered the novel guiding principle to be beneficial to industrial processing of rubber materials.

 ゴム材料をはじめとする有機系ソフトマテリアルの工業的に最も有利な点は成形加工性に優れることであり、その起源はエントロピー弾性による低弾性率と高変形性にある。しかし、本来の低弾性率ゆえに、工業用材料として活用するためには、補強性フィラーの充填が欠かせない。また、きわめて巾広い緩和時間分布を有し、その緩和時間が温度によって幅広く変化する。したがって、フィラー充てんゴムの粘弾性を一般的に取り扱うことは困難に思える。例えば、時間-温度移動因子がフィラーの種類に依存するという報告と依存しないという報告が混在し、混乱もあった。しかし、無定形高分子の温度依存性は単純なWLF式で表され、その移動因子は分子量、分子量分布、からみ合いの有無やからみ合いの程度に依存しないことが知られており、基本的には単純である可能性がある。そこで、本研究は、さまざまなフィラーを充填したゴム材料の動的弾性率を幅広い温度範囲、周波数範囲で測定し、フィラー充てんゴム材料粘弾性の温度依存性を総合的に検討するとともに、非線形粘弾性発現機構の解明、ならびにその応用を目的としている。
 第1章では、序論として、本研究の背景、意義および目的について述べるとともに、生ゴムおよびフィラー充てんゴムの架橋物、非架橋物の温度依存性に関する問題点と非線形性発現機構を概観し、詳細に検討するための基本的な考え方と有効な観測法について論じている。
 第2章では、まず、フィラー充てんゴムの粘弾性における時間-温度換算則の重要性と問題点を総括した上で、典型的な補強性フィラーの一つであるカーボンブラックを取り上げ、フィラーの有無ならびに架橋点の有無が対象ゴム試料のガラス転移温度に及ぼす影響について、当該試料の線形動的弾性率を幅広い温度範囲、周波数範囲で観測したデータを基に、議論している。また、同試料の非線形粘弾性の温度依存性とも比較し、検討している。
 第3章では、第2章の結果を踏まえ、さらにさまざまな種類のフィラーを充填したゴム材料粘弾性の温度依存性に及ぼすフィラー効果について総合的に論じ、1.架橋点は系のガラス転移温度を変化させるが、フィラーの有無、およびフィラーの種類によってガラス転移温度は変化しないこと、2.ガラス転移温度を基準温度に選べば、ゴム材料粘弾性の温度依存性はフィラーの有無、フィラーの種類、並びに、分子間架橋の有無によらない普遍関数で書けることを明らかにしている。
 第4章では、高分子濃厚系の非線形粘弾性発現要因が歪誘起からみ合い数減少と高分子鎖の鎖配置異方性の複合によることを考察した上で、鎖配置異方性が間違いなく非線形性発現要因であることを実験的に証明している。
 第5章では、この考え方を発展させ、鎖配置異方性を固定して導入することにより、ゴム材料のエネルギーロスを加工工程により制御可能であることを実験的に実証している。
 これら一連の検討の結果、フィラー充てんゴム材料の粘弾性の温度依存性はマトリックスポリマーのそれで決まり、フィラーはタイムスケールを変化させるのではなく、弾性率絶対値を変化させるのであることを明らかにした。この知見は、フィラー充てんゴム材料の加工性シミュレーションにおいて、温度-時間効果と補強効果を独立した形で扱えることを意味し、成形加工にも資する指針を与えた。
 このように本論文は、粒子補強性有機材料の力学特性解明とその応用に大きく寄与するものであり、工学上及び工業上貢献するところが大きく、博士(工学)の学位論文として十分な価値を有するものと認める。

平成19(2007)年度博士論文題名一覧

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