Abstract
近年來由於社會高度成長，很多機器設備(稱作系統) 常被用來製造產品或是擔任傳艾服務的工具,且最些系統相當昂貴和精密。一但系統因外在環境的影響或因本身的磨損而發生失效時,將會導玫較大的運轉成本及較低的產品品質。因此其間最大問題就在於如何維持系統高度的製程能力且將運轉成本降到最低，簡單的說，高可靠度產品的獲得，固然可利用優良的物料、精密的機械、以及受過良好訓練的作業員等要項來達成，然而系統適切地執行預防保養及置換(Preventive Maintenance /orreplacement)，將直接影到生產能力，也是一項重要的先決條件。本研究之主要的目的，在於對單元件系統或是多元件系統(Single-Unit orMulticomponent Systems )的各種置換模式(Replacement Models )做一番探討並訂定出適當的置換策略。依據所考慮的系統或者是失效模式之不同，我們將此研究分成四大主題：(1) 對於容易受隨機發生之衝擊(Shocks) 所影響的單元件系統，依據不同的決策變數及不同的衝擊型態，我們探討了三個替換模式並且找出最佳的替換策略。(2) 對於容易受隨機發生之不且乘數的衝擊(Shock of multiplicities ) 所影響的並聯系統(Parallel Redundant System )，我們提出一個週期式的替換模式並求出最佳的替換週期(Optimal Replacement Period )。(3) 針對一個二元件系統(Two-Component System)，且兩個元件之間有幾率性失效的交互作用(Probabilistic Failure Interactions )，依據不同的決策變數，我們提出了三個替換模式並且討論最佳的替換策略存在的條件：(4) 針對由N 個元件組成的並聯系統，且這些元件容易受隨機及共同肇因失效(Random and Common Cause Faulures )所影響，依據失效後修護時間不同的設定，我們提出了兩個替換模式並找出最佳的重置數( Redundancy ) 及替換策略。在每一個主題□，我們都將提出最佳策略存在的條件並列舉例子以說明之。///////Systems used in the production of goods and delivery of servicescondtitute the vast majority of the most industial capital. These systemsare subject to random failures or deterioration due to usage andenvironmental influence. System faulures are often reflected on higheroperation costs and lower product quality. To keep operation cost downwhile maintaining good quality, preventive maintenance and/or replacementare often performed. This research is to investigate several replacementmodels for the single-unit or multicomponent systems in which the faulurepatterns or deterioration processes are described in terms of stochasticprocesses. Such replacement problems can be classified, depending ondifferent systems or different failure patterns which ar considered, intofour groups: 1) three replacement Models are studied for a single-initsystem which is subject to shocks, 2) the periodic replacement policy isdiscussed for a parallel redundant system of N-identical components whcihis subject to shocks of various multiplicities, 3) three replacementmodels are studied for a two-component system having probabilistic faulureinteractions between components, and 4) cost-optimal replacement policy(N*,n* ) is discussed for a parallel redundant system of N-identicalcomponents in which the system is allowed to undergo a prefixed number nof repairs before to be replaced. The condition for the existence ofoptimal values are studied and numerical examples introduced forillustration.