台灣幅員狹小，天然資源不足，唯有藉著大量出口才能換取外匯，情況使得台灣逐漸發展成一小型開放經濟。長久以來，美國一直是台灣最大的貿易夥伴，使得台灣產品對美輸出的多寡往往直接影響台灣總體經濟的表現。隨著政府外匯政策的逐漸自由化，匯率在總體經濟中所扮演的角色也越顯重要。近幾年來，台幣匯價在外匯市場上時有波動，不但影響政府政策的擬定、經貿活動的往來，外匯市場上的投炒作更造成熱錢的流動。是故，新台幣對美元匯率的決定及波動因素是值得我們深入探討的課題。基於此點，本文擬建立一個可供實証的小型開放經濟模型，試圖探討新台幣對美元匯率的決定因素。首先，參照Frankel(1979)所提出的實質利率差價模型(Real Interest Rate Differential Model)，作為實証研究的基礎。其次，利用Johansen(1988,1991)、Johansen & Juselius(1990)的共整合(cointegration)分析方法，以台灣地區1981年至1993年間的月資料，驗証縮減式的長期關係是否成立。最後，採用誤差修正模型(error correction model)，估計匯率的動態調整途徑，並對匯率變動率進行樣本後預測。 　　實証結果發現：(1)實質匯率差價模型所刻畫的匯率與其他經濟變數的長期關係在台灣是可以成立的；(2)傳統貨幣學派對兩國結構喜數相同的假設過於嚴苛，對於台灣及美國並不適用；(3)除了名目利率外，台灣及美國的貨幣供給、產出水準及通貨膨脹率具有一對一的關係；(4)以誤差修正模型預測台幣／美元匯率變動率，其效果優於隨機漫步模型。

<p dir="ltr">Within the aerospace community in recent years, there has been a marked increase in interest in cislunar space. To this end, the study of the dynamics of this regime has flourished in both quantity and quality in recent years, spearheaded by the use of simplified dynamical models to gain insight into the dynamics and to generate viable mission concepts. The most popular and simple of these models, the Circular Restricted Three-Body Problem, has been thoroughly explored to meet these goals (even well-prior to the recent spike in interest). Much work has been done investigating periodic orbits within these models, and similarly has been performed on non-periodic transfers into periodic orbits. Studied less is the superposition of these two concepts, or using periodic orbits as a way to transit, for example, cislunar space. In this thesis, the development of periodic orbits amenable to transiting is accomplished. Beginning from periodic orbit families already present in the literature, this research finds a novel and useful family of periodic orbits, here dubbed the spatial 2:1-resonant orbit family. Within this newly-discovered family, multitudes of qualitative behaviors interesting to the astrodynamics community are found. Many family members seem accommadating to a diverse set of mission profiles, from purely-unstable family members best suited to use as transfers, to marginally stable ones best suited to longer-term use. This family as a whole is analyzed and catalogued with thorough descriptions of behavior, both quantitative and qualitative. While the Circular Restricted Three-Body Problem serves as an excellent starting point for analysis, trajectories found there must be generalized to higher-fidelity modeling. In this spirit, this thesis also focuses on demonstrating such generalization and putting it into practice using the more sophisticated Elliptic-Restricted Three-Body Problem. Documentation of the numerical tools necessary and helpful in accomplishing this generalization is included in this work. Prototypically, the truly 2:1 sidereally-resonant unstable member of the 2:1 family is transitioned into the elliptic problem, as is a nearly-stable L2 Halo orbit family member. This new trajectory is paired with a more classically-present example to show the validity of the methodology. To aid this analysis, symmetries present within the elliptic model are also explored and explained. With this analysis completed, this orbit family is demonstrated to be both interesting and useful, when considered under even more realistic modelling. Further work to mature this novel family of orbits is merited, both for use as the fundamental building block for transfers and for use for more-permanent habitation. More broadly, this work aims to achieve a further proliferation of the merger between transfer and orbit, concepts which seem distinct at first, but deserve more gradual consideration as different flavors of the same idea.</p>