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Monetary policy has been given either too many positive attributes or, in contrast, only economy-disturbing features. Central banks must take into account a wide variety of factors to achieve a proper characterization of modern economies for the optimal implementation of monetary policy. Such is the case of central bank accountability and monetary policy effectiveness. The objective of this dissertation is to examine these two concerns relevant to the current macroeconomic debate. The analyses are carried out using an innovative set of tools to extract presumably important information from historical data of selected macroeconomic indicators. This dissertation consists of three essays. The first essay explores the causality between the elements of the "celebrated" Taylor rule, using a Structural Vector Autoregression approach on US data. Directed acyclical graph techniques and Bayesian search models are used to identify the contemporaneous causal structure in the construction of impulse-response functions. Further analysis is performed by evaluating the implications of performing standard innovation-accounting procedures, derived from a Structural Vector Autoregression on interest rates, inflation, and unemployment. This is examined whenever a causal structure is imposed vs. when it is observed. We find that the interest rate causes inflation and unemployment. This suggests that the Fed has not followed a Taylor rule in any of the two periods under study. This result differs significantly to the case when the causal structure is imposed. The second essay presents an incentive-compatible approach based on proper scoring rules to evaluate density forecasts in order to reduce the central banks' accountability problem. Our results indicate that the surveyed forecasters have done a "better" job than the Monetary Policy Committee (MPC). The third essay analyzes the causal structure of the factors that are presumed to influence the effectiveness of monetary policy, represented by the sacrifice ratio. Directed acyclical graph methods are used to identify the causal flow between such determinants and the sacrifice ratio. We find evidence that, while wage rigidities and central bank independence are the two major determinants of the sacrifice ratio, the degree of openness has no direct effect on the sacrifice ratio.

The frequency of on-site systems for treatment of domestic wastewater is increasing with new residential development in both rural and low-density suburban areas. Subsurface flow constructed wetlands (SFCW) have emerged as a viable option to achieve advanced or secondary treatment of domestic wastewater. The pollutant removal efficiency in SFCW depends on design parameters. Many of these factors have been investigated while others such as aspect ratio, design of water inlet structure and method of dosing the wetland have yet to be fully examined. This study examined the effect of aspect ratio and header design on BOD5 removal efficiency as well as the impact of flow rate on flow distribution in a SFCW. An aspect ratio of 4:1 achieved 10% greater removal of organic matter than a 1:1 ratio. Tracer studies demonstrated that wetlands loaded at a constant rate of 3.8 L/min and 7.6 L/min experienced preferential flow. In addition, tracer studies showed wetlands with leaching chambers as headers failed to achieve equal flow distribution. An improvement in effluent water quality was achieved by replacing the leaching chamber for a perforated manifold as the inlet structure. This study demonstrated the importance of the careful selection of aspect ratio and means by which water is introduced to the wetland in the design of SFCW.

A multinational enterprise may adopt a tax avoidance mechanism under the contribution of paid-in capital to its subsidiary in Taiwan is decreased, while increasing its loans to the subsidiary as much as possible. This may result in the minimization of the taxable income of the subsidiary through the increase in interest expense deduction of the subsidiary. Under such an arrangement, non-deductible dividend payments are replaced with deductible interest payments. Anti-thin capitalization that was originated from the arm's length principle is adopted from Article 9(1) of the OECD Model Tax Convention. Many countries set a fixed debt-equity ratio as a safe harbor to anti-tax avoidance. In this paper, we use factor analysis to find the optimal debt-equity ratio under the optimal capital structure model. The purpose of this study is to find an optimal debt-equity ratio and propose suggestions in order to revise the law and advance tax system.

Suppose G is a graph with n vertices and m edges. Let n¡¬ be the maximum number of vertices in an induced bipartite subgraph of G and let m¡¬ be the maximum number of edges in a spanning bipartite subgraph of G. Then b(G) = m¡¬/m is called the bipartite density of G, and b∗(G) = n¡¬/n is called the bipartite ratio of G. It is proved in [18] that if G is a 2-connected triangle-free subcubic graph, then apart from seven exceptional graphs, we have b(G) ≥ 17/21. If G is a 2-connected triangle-free subcubic graph, then b∗(G) ≥ 5/7 provided that G is not the Petersen graph and not the dodecahedron. These two results are consequences of a more technical result which is proved by induction: If G is a 2-connected triangle-free subcubic graph with minimum degree 2, then G has an induced bipartite subgraph H with |V (H)| ≥ (5n3 + 6n2 + ǫ(G))/7, where ni = ni(G) are the number of degree i vertices of G, and ǫ(G) ∈ {−2,−1, 0, 1}. To determine ǫ(G), four classes of graphs G1, G2, G3 and F-cycles are onstructed. For G ∈ Gi, we have ǫ(G) = −3 + i and for an F-cycle G, we have ǫ(G) = 0. Otherwise, ǫ(G) = 1. To construct these graph classes, eleven graph operations are used. This thesis studies the structural property of graphs in G1, G2, G3. First of all, a computer algorithm is used to generate all the graphs in Gi for i = 1, 2, 3. Let P be the set of 2-edge connected subcubic triangle-free planar graphs with minimum degree 2. Let G¡¬ 1 be the set of graphs in P with all faces of degree 5, G¡¬2 the set of graphs in P with all faces of degree 5 except that one face has degree 7, and G¡¬3 the set of graphs in P with all faces of degree 5 except that either two faces are of degree 7 or one face is of degree 9. By checking the graphs generated by the computer algorithm, it is easy to see that Gi ⊆ G¡¬i for i = 1, 2, 3. The main results of this thesis are that for i = 1, 2, Gi = G¡¬i and G¡¬3 = G3 ¡åR, where R is a set of nine F-cycles.

Luminescent emission of partially conjugated homopolymers was successfully demonstrated as light emitting diodes (LEDs). A series of coil-like heterocyclic aromatic poly(2,2¡¦-phenyl-5,5¡¦-bibenzimiazole) (Pbi) was synthesized and derivatized with alkyl pendants for changing the band gap to form different electroluminescence (EL) emissions. Because of the entropy and van der Waals' interaction, multi-wall carbon nanotube (MWNT) tends to aggregate. In this investigation, chemical synthesis was applied to functionalize the MWNT. MWNT was esterificated by incorporating the functional group (-COOC10H21) to reduce its aspect ratio to facilitate its dispersion in the Pbi solution. MWNT-COOC10H21 was analyzed using Fourier transform infrared, elemental analysis, Raman spectrum and thermogravimetric analysis. In the polymer light emitting devices, Pbi mixed with MWNT-COOC10H21 would decrease threshold voltage for about 2 V, and the device emission current was increased 5~10 times of magnitude than those of devices without MWNT- COOC10H21. Pbi was in-situ polymerized with acidified multi-wall carbon nanotube (MWNT- COOH) for polymer LED fabrication. The emission current of these devices was still increased 10~15 times but no threshold voltage decrease compared to those of Pbi polymer solution-mixed with MWNT-COOC10H21. The polymer LED Commission International del'Eclairage chromatic indices were about the same for Pbi mixed with MWNT-COOC10H21 or in-situ polymerized with MWNT-COOH.

Planetary gear mechanisms are widely used in automobile automatic transmissions. However, the relevant design theories are not well development, especially the synthesis of the clutching sequence. Thus, the purpose of this study is to develop a systematical methodology for the design of automobile automatic transmissions. First, the specifications are established according to the characteristics of the automatic transmissions. Second, a procedure is created to list the speed ratio table and the clutching table for the planetary gear mechanisms. Third, based on the clutching table, a systematical method is developed to synthesize the clutching sequences. Then, the clutches and brakes are arranged into the planetary gear mechanisms to form the schematic of an automatic transmission. Finally, according to the relations between speed ratios and the numbers of teeth of gears, the gear-teeth synthesis is carried out when several certain speed ratios are assigned. A seven-link 2-DOF Ravigneaux gear mechanism, a eight-link 2-DOF Ravigneaux gear mechanism and a nine-link 2-DOF stepped Ravigneaux gear mechanism are as the design examples. And a four-speed, a six-speed and an eight-speed automatic transmissions are synthesized, respectively. The result of this study shows that the proposed methodology can be applied to design any 2-DOF planetary automatic transmissions.

In this work, copula models for fitting bivariate response data with Weibull marginal distributions are studied, which are motivated by the need of model fading channels in signal applications. The analytical expressions for the joint probability density function (p.d.f.), and joint cumulative distribution function (c.d.f.) are utilized as the bivariate distribution of the fading channels data with not necessarily identical fading parameters and average powers. The performances of outage probability employing diversity receivers, called as selection combining (SC), equal-gain combining (EGC), and maximal-ratio combining (MRC) of two diversity receivers under bivariate copula models with Weibull marginal distributions are presented. They are also compared with the results in Sagias (2005) where the data assumed to follow the bivariate Weibull distribution. It will be demonstrated that the copula models can approximate the bivariate Weibull distribution used in Sagias (2005) very closely with suitable copula model, and the computations for obtaining the performances of outage probability under SC are much simplified. Keywords and phrases: equal-gain combining, maximal-ratio combining, selection combining

This study is focused on the technique for fabrication of high aspect ratio nanostructures by combining both the advantages of maskless patterning of focused ion beam (FIB) and anisotropic etching of inductively coupled plasma etcher (ICP) in CF4 atmosphere. The materials contain p-type (100) single crystal silicon and thermal silicon dioxide. The study details include¡G (1) The reliability of AFM when scanning isotropic and anisotropic nanostructures with high aspect ratio tip in tapping mode. (2) FIB direct writing test. (3) The influences of ICP parameters including ICP power, bias power, content of oxygen, and process pressure. After completion of above-mentioned items, an optimized condition is used to get the anisotropic Si-based high aspect ratio nanostructures of holes array, gratings and cylinder under 100nm. The smallest line width of single crystal silicon gratings is 48nm, and aspect ratio up to 2.36. The smallest line width of silicon dioxide gratings is about 100nm, height is 410nm and aspect ratio up to 2.36 measured by SEM. By combining both advantages of different systems, we can provide another simple and rapid method for nanofabrication.