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Internal solitary waves (ISW) have been detected on the interface of a stratified water column in the ocean. It is believed that ISW could affect oil drilling operations, nutrient pumping, and acoustic signal obstruction. In the ocean, the thickness of a pycnocline is finite which differs with the theoretical assumption as being a thin layer. This thesis reports the effect of an ISW propagation in various pycnocline thicknesses. Laboratory experiments were conducted in an internal wave flume (0.5¡Ñ0.7¡Ñ12m) at the National Sun Yat-sen University, Kaohsiung, Taiwan. ISW in depression or elevation type were generaled using a stratified two-layer fresh/brine water system with a total depth of 50 cm in the flume. Upon creating an ISW propagating on a flat bed or over a triangular obstacle later, several physical parameters of the ISW (i.e. wave amplitude, phase speed, characteristic wave length, and wave energy) were measured or calculated for different thicknesses of the pycnocline. The major controlling factors in the experiments included the depth ratio of the upper to lower layer H1/H2, interface displacement £b0 between the wave generating chamber and the main flume, and the thickness of the pycnocline. The thickness of the pycnocline was estimated from the result of density profile in the vertical direction in the flume, experiments under the same H1/H2 and £b was terminated when the pycnocline thickness became large enough. As the thickness of the pycnoline increased, the values of all the physical parameters (including wave amplitude, phase speed, and wave energy) under consideration decreased. Their reduction rates were more significant in the case of small interface displacement (£b0=10cm) than that with large £b0=15cm. On the other hand, the changes in the physical variables associated with a depression ISW were more significant than those in an elevation ISW.

Spray cooling is a promising technique which is used to remove large amounts of heat from surfaces. It is characterized by uniform heat removal, low droplet impact velocity and better cooling efficiency when compared to other cooling schemes. It can be used in electronic cooling, and other applications. However, due to the multiple impacts of droplets, the film fluid dynamics and morphology are quite complicated. Moreover, the effect of heat transfer under spray cooling is not well understood due to the large number of interdependent variables such as impact spacing, impact angle, droplet diameter, droplet velocity and droplet frequency to name a few. An experimental approach is proposed and used to minimize and control key independent variables to determine their effects on surface temperature and heat transfer cooling mode. The effects of droplet impact angle and spacing on different heat flux conditions are studied. The film thickness is also obtained to further investigate the relationship between the independent variable and the observed heat transfer mechanism. The study of coherent droplet impingement on an open surface is experimentally characterized using high speed imaging and infrared thermography. Single stream droplet impingent cooling with different impact angle is also studied. Temperature distribution and impact crater morphology are obtained under different heat flux conditions. Film thickness inside droplet impact craters is measured to understand the relationship between minimum surface temperature and film thickness. Next, double streams droplet impingement cooling with different spacings and impact angles are investigated. The optimum spacing is found to reduce the droplet-to-droplet collision and to minimize splashing, resulting in enhanced heat transfer and better use of the cooling fluid. The film thickness is also measured to understand the relationship between the heat transfer results and the controllable independent variables. The results and conclusions of this study are useful in understanding the physics of spray cooling and can be applied to design better spray cooling systems.

Children born prematurely exhibit a broad range of neuroanatomical abnormalities. The aim of this study was to investigate the long-term effects of very preterm birth on brain volume (cortical and subcortical), cortical thickness and surface area. The participants were 25 children born very preterm (<32 weeks gestational age) without significant post-natal medical sequelae and 32 term-born children between 7 and 10 years of age. Neuroanatomical measures were derived from an automated pipeline. The results suggest a pattern of decreased brain volume, surface area and cortical thickness for children born preterm and the relation between subcortical gray volume and total brain volume differed between groups. The cortex was significantly thinner for children born preterm than term-born children in focal regions of the parietal and temporal lobes. Therefore, even without significant postnatal medical sequelae, very preterm children still exhibit structural differences that persist into middle childhood.

Children born prematurely exhibit a broad range of neuroanatomical abnormalities. The aim of this study was to investigate the long-term effects of very preterm birth on brain volume (cortical and subcortical), cortical thickness and surface area. The participants were 25 children born very preterm (<32 weeks gestational age) without significant post-natal medical sequelae and 32 term-born children between 7 and 10 years of age. Neuroanatomical measures were derived from an automated pipeline. The results suggest a pattern of decreased brain volume, surface area and cortical thickness for children born preterm and the relation between subcortical gray volume and total brain volume differed between groups. The cortex was significantly thinner for children born preterm than term-born children in focal regions of the parietal and temporal lobes. Therefore, even without significant postnatal medical sequelae, very preterm children still exhibit structural differences that persist into middle childhood.

An investigation was conducted to determine whether a “size effect” phenomenon for one particular thermophysical property, thermal conductivity, actually exists for amorphous poly(methyl methacrylate) (PMMA) films with thicknesses ranging from 40 nm to 2 μm. This was done by using a non-contact, non-invasive, in-situ Transient Thermo-Reflectance (TTR) laser based technique. The results demonstrated that the intrinsic thermal conductivity of a 40 nm PMMA film deposited on native oxide of silicon increases by a factor of three over bulk PMMA values, and a distinct increase in the thermal conductivity of PMMA film was observed in ultra-thin (sub 100 nm) films. This confirmed the importance of film thickness for the through-plane thermal conductivity value of PMMA film on native oxide of silicon.

The prime function of lubricating additives are to strength or improve the effect of lubrication and the unti¡Vwear capability of lubricating base oil. This research use the self-development EHL tester to explore the effects of ellipticity parameter of ring , load, speed, concentration and particle of lubricating additives and slip ratio on the film thickness.. During pure rolling, the film thickness increases with increasing speed, but decreases with increasing load, and the effect of speed on the film thickness is more obvious than the effect of load. The film thickness of lubricating additives varies insiginificant when the concentration of lubricanting additives are 1% and 3%, but it increases evidently at 7%. The effect of concentration developes good function of lubricant just under the condition of high speed and low load. Smaller particle of MoS2 has better lubricant effect than that it bigger. The number of particle of MoS2 distributed over lubricant contact zone increase with increasing concentration . The film thickness is getting thick when the ellipticity parameter increases. The minimum film thickness and central film thickness will decrease when slip ratio increase. That means , slip ratio and film thickness have a inversive relationship. Furthermore, when slip ratio increases, the central film thickness will decrease rapidly, but the minimum film thickness will just have a gentle decrease. It still has lubricant effect under the roll-slip state when the particles are smaller. During pure slipping, the bigger the particles, the easier it piles up on the entering area, and it makes lubricating oil can not enter the contact area easily.

Abstract Elastohydrodynamically lubricated conjunctions are often subjected to impact loading. In such case the squeeze effect plays an important role. This research uses a self-development EHL tester to explore the effects of squeeze velocity, load and viscosity of lubricant on the dimple film thickness occurs between two components approach each other. The contact region is studied by means of optical interferometry using white light, a microscope and a CCD camera recording equipment. The results of the test show that increasing squeeze velocity makes the dimple deeper. Furthermore, the maximum central dimple film thickness becomes greater as the viscosity of lubricant increases at the same experiment condition. When the squeeze load is larger, it will keep the dimple film longer.

Organic light-emitting Diode (OLED) emits light itself. It owns many advantages of optical-electronic characteristics as compared with Thin Films Transistor-Liquid Crystal Display (TFT-LCD). In order to achieve the requirement for full color flat panel display, the three primary colors which are red, green, blue (R,G,B) with high luminance¡Bhigh current efficiency¡Band high color purity are important study of research and development for OLED. In our experiment, the major materials are NPB¡BDPVBi¡BAlq3¡BLiF¡BPBD¡BDCJTB¡FThe materials of NPB¡BDPVBi¡BAlq3,LiF is used as hole transporting layer¡Bblue emission layer¡Belectron transporting layer, and electron injection layer, respectively. PBD is hole-blocking layer and DCJTB is red emission layer which is intended to indirectly demonstrate the hole-blocking effect in the interface between NPB and DPVBi layer. The blue light emission with short wavelength plays an important role in color conversion method (CCM) of full color technology. In the study, we improve and research on color purity of blue OLED by various thicknesses of organic layer. In addition, we research the influence of the device with different thicknesses of PBD layer as hole-blocking layer. In order to improve the color mixing phenomenon, we add extra DPVBi layer to the device with PBD layer. It can improve the blue color purity and obtain narrower full width at half maximum (FWHM).