Even though the framework of mean-variance analysis is convincing, in practice, investors encounter serious drawbacks. Understandably, a more stable and rather simple method to make investment decisions without depending on the expected returns would obviously be preferred by some investors. In this study, we adopt a newly proposed equally-weighted risk contribution portfolio (ERC), without the assumption of expected returns, in order to observe its risk and return, as well as the timing of use compared to different benchmarks, the Taiwan 50 index (TWN50) and Taiwan weighted index (Y9997). For comparison, we adopt the other two commonly used methods, the minimum variance portfolio (MVP) and the equal weight portfolio (EW). It is interesting to observe the ERC¡¦s risk and return profile because, similar to the EW, it invests in every asset in a portfolio while adjusting weights to consider the marginal risk between each component. Therefore, no individual asset¡¦s risk contribution is dominated by an other and they all have the same risk contribution. In addition, to strike a balance between risk control and pursuing excess return, we incorporate arbitrage portfolios into the standard ERC portfolio; to satisfy the standard of the passive funds, we combine the minimum tracking error portfolio with the standard ERC portfolio by a specific ratio. From the TWN50 and the Y9997 cases, we presume that the problem relating to whether or not the benchmark is a full sample or a partial sample and whether it¡¦s replicable, affects the performance of the ERC. If our benchmark is a partial sample like the TWN50, the ERC strategy can outperform the benchmark and even provides some degree of defensive ability when the market trend is down.

A new full-wave surface impedance integral equation method is presented for three-dimensional arbitrary-shaped interconnect parasitic extraction in layered media. Various new ways of applying voltage and current excitations for electromagnetic-circuit simulation are introduced. A new algorithm is proposed for matrix formation of electromagnetic-circuit simulation, low frequency solution and layered media so that it can be easily integrated to a Rao-Wilton-Glisson based method of moment code. Two mixed potential integral equation forms of the electric field integral equation are adapted along with the Michalski-Mosig formulations for layered kernels to model electromagnetic interactions of interconnects in layered media over a conducting substrate. The layered kernels are computed directly for controllable accuracy. The proposed methods are validated against existing methods for both electromagnetic and electromagnetic-circuit problems.

Dependencies in multilevel models at the second level have never been thoroughly examined. For certain designs first-level subjects are independent over time, but the second level subjects may exhibit nonzero covariances over time. Following a review of revelant literature the first study investigated which widely used computer programs adequately take into account these dependencies in their analysis. This was accomplished through a simulation study with SAS, and examples of analyses with Mplus and LISREL. The second study investigated the impact of two different missing data techniques for such designs in the case where data is missing at the first level with a simulation study in SAS. The first study simulated data produced in a multiyear study varying the numbers of subjects in the first and second levels, the number of data waves, the magnitude of effects at both the first and second level, and the magnitude of the second level covariance. Results showed that SAS and the MULTILEV component in LISREL analyze such data well while Mplus does not. The second study compared two missing data techniques in the presence of a second level dependency, multiple imputation (MI) and full information maximum likelihood (FIML). They were compared in a SAS simulation study in which the data was simulated with all the factors of the first study and the addition of missing data varied in amounts and patterns (missing completely at random or missing at random). Results showed that FIML is superior to MI because it produces lower bias and correctly estimates standard errors

Amorphous polymers under their glass transition temperature (Tg) exhibit large inelastic deformations. Their mechanical behavior is highly dependent upon temperature, strain rate, pressure and loading mode (tension, compression, shear). They also exhibit small strain isotropic hardening, softening and large strain anisotropic rehardening. In addition, while in their glassy state, polymers are far from thermodynamic equilibrium so that their properties may change over time (physical aging). This complex behavior is reflected in the response of composites and affects the onset and propagation of damage therein. Therefore, in order to design polymer composite structures, it is fundamental to develop relevant tools and methodologies which aim at understanding, capturing and predicting the full thermomechanical response of glassy polymers. In this study, the thermomechanical behavior of a thermosetting polymer epoxy is characterized experimentally for temperatures below Tg. The intrinsic behavior of the polymer is obtained using a new methodology based on digital image correlation (DIC) in combination with video-monitored extensometry. In particular, inelastic flow localization patterns are discussed based on the full-field strain measurements and their connection to the stress-strain curves are highlighted. The Boyce-Parks-Argon polymer constitutive model, hereafter called the macromolecular model, has been enhanced to describe the thermomechanical behavior of epoxies. The identification of the material parameters involved in the model is described in a detailed procedure that builds on a limited set of experiments. The model is shown to represent adequately the thermomechanical behavior of the studied epoxy over a wide range of temperatures and strain-rates. Using additional high strain-rate data obtained from collaborators on Kolsky bars, the model capabilities are further discussed. Using finite-element implementations of the constitutive model in both quasi-static and dynamic codes, the processes of plastic flow localization are analyzed in tensile and compression specimens. Such analysis can form the basis of an alternative method for identifying the model parameters through inverse identification. Finally, a preliminary set of experiments were also conducted to investigate the effect of physical aging on the yield behavior and enhance the macromolecular model with the capability of modeling aging effects. Our interpretation of the aging experiments suggests that they are not conclusive and do not permit full determination of model parameters. Specific recommendations are tentatively formulated for conducting aging experiments in the future.

Being located in subtropical area, the weather in Taiwan is hot and humid which imposing huge cooling load on buildings. Conventionally, central air-conditioning plants were designed using refrigerant compressors to make chilled water, and then pumped through the zone pumps to meet the cooling load, providing air-conditioning by Fan Coil Unit (FCU) or Air-Handling Units (AHU) by ductwork. To meet the varying cooling demand, two important systems were developed for energy savings, namely, the Variable Water Volume (VWV) system, and the Variable Air Volume (VAV) system, which has been widely adapted in Taiwan area. The working principle is mainly devoted to adjusting the volume of the chilled water and/or air volume delivered through inverter-driven pimps and fans to achieve energy saving. On the other hand, recently in Japan, an important energy-saving air-conditioning system has been developed which directly varying the refrigerant flow rate to meet the varying cooling demand by inverter-driven compressors, named VRV system. Comparative to the conventional air-conditioning system, the heat exchange mechanism of the VRV system has been effectively enhanced by direct exchange of the refrigerant and the cool air, which is in effect a combination of the VWV and VAV system. It provided huge energy saving potential for the application on buildings with moderate cooling loads, such as 100 USRT or so. It is the goal of this research project, to evaluate the performance of the VRV system in Taiwan¡¦s hot and humid climate, by performing full-scale experimental investigation so that energy savings effect can be validated quantitatively. Since VRV system is fairly new in Taiwan, the validation of the system performance under local weather condition is of particular importance. It is anticipated that through the changing of the operation conditions, such as different outdoor conditions, various partial load conditions, and different scheduling of the VRV system, the power consumption of the VRV vs. conventional system can be compared precisely and quantitatively. These experimental data will, in turn, provides valuable reference to the establishment of the building energy consumption index in Taiwan, which outwits the direct adoption of the foreign data such as from Japan, in achieving a much reliable database.

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Fluorescent lamps are in general driven by ac ballasting currents. The cyclic variation in arc discharging power results in light fluctuation at twice the frequency of the ac current. Light fluctuation may be intolerable when a steady light output is required in some particular applications. To eliminate light fluctuation, an electronic ballast with dc current is proposed to operate the fluorescent lamp at a constant power. The main power conversion of the electronic ballast employs the single-stage high-power-factor inverter, which is originated from a combination of the half-bridge resonant inverter and the buck-boost converter. With such a circuit configuration, the output power can be regulated by asymmetrical pulse-width-modulation. The ac output of the inverter is then rectified and filtered to provide the dc ballasting current. Driven by dc current, however, the fluorescent lamp emits electrons unilaterally from one end leading to wearing out of emission material on the cathode filament. To solve this problem, an inverter is integrated for commutation of the lamp electrodes. Furthermore, a preheating control is included to start the fluorescent lamps with zero glow-current. A prototype is designed and built for the OSRAM T5-80W fluorescent lamp. The dc operating characteristics of starting transient, light fluctuation, lighting spectra, color temperature as well as the light fluctuation are investigated from experiments. Experimental results also show that the electronic ballast is capable of high-power-factor, dimming capability and zero glow-current preheating.

The existing local fire code ¡§Standard for Installation of Fire Protection Facilities in Classified Areas¡¨ is prescriptive in nature and suitable for buildings, which can be well compartmented. It also described the minimum requirement for specific system designs such as fire and smoke compartmentation, mechanical smoke extraction rate, etc. on item 188. In this reserch, the concourse level encountered large spaces and is the vital part for passengers¡¦ movement, either under normal condition or in emergency cases. Therefore, a performance-based fire engineering design has been exercised which is also allowed in local fire code subject to approval from the authorities having jurisdiction. First, a comparative study of the code compliances should be addressed, with the alternative design options supported by 3D CFD simulation. The FDS (Fire Dynamic Simulation) program was utilized for this reserch for 3D CFD simulation. It is developed by the National Institute of Standards and Technology (NIST) of U.S.. FDS is a computational fluid dynamics (CFD) model of fire-driven fluid flow. The software solves numerically a form of the Navier-Stokes equations appropriate for thermally-driven flow with an emphasis on smoke and heat transport from fires. Secondly, it is decided that a full-scale hot smoke test should be conducted to validate the smoke management system performances under the as-built conditions. It can be summarized that, following the NFPA 92B N-percentage Criteria, both test 1 and test 2 results indicated that the hot smoke tests are successful, in validating that a sufficient smoke clear height can be maintained for safe evacuation should a 5 MW t-squared fast fire occurred at the concourse level. Finally, following the NFPA 130 and NFPA 92B as the design guides, the performance-based fire safety engineering design conducted in concourse level, is successful through 3D CFD simulations and full-scale hot smoke test. A smoke¡Vfree escape route can be maintained for a period of time much longer than needed for the worst case fire scenario which warrants a safe evacuation in case of a 5 MW fire occurred on concourse level.

The thesis is related to investigate characteristics and performance of a Z-source full bridge dc/dc converter which boosts the input voltage to a higher output voltage. Zsource structure increases the reliability of the converter according to current fed full bridge dc/dc converter and also reducing the complexity according to two stage design approach (boost followed by full bridge). Operating principles of the Z-source dc-dc converter is described by current and voltage waveforms of the components and mathematical expressions. Moreover, small signal models and transfer functions are derived for both continuous current mode (CCM) and discontinuous current mode (DCM) operations of the converter. Waveforms obtained, mathematical expressions, small signal models and transfer functions derived are confirmed by simulations. Performance of the converter and controller are both tested in laboratory prototype.

Many large space buildings have been built in Taiwan during the past decade and people are very concerned about the fire safety inside the large space. Therefore, a performance-based smoke management system with makeup air system has been exercised. For steady flow, the mass flow of air or smoke exhaust from the top of an atrium equals the mass flow of air entering below the smoke layer. This airflow entering the atrium is referred to as makeup air, and the makeup air can be either supplied naturally or by fan power. In this research, various full-scale hot smoke tests for makeup air systems will be performed to evaluate the temperature distribution of smoke layer and the smoke descending rate at ABRI large space fire lab in Tainan. The experimental results obtained will be utilized as an important reference to establish the code of smoke management system with makeup air system in Taiwan.