This thesis contains four parts. In the first part, we investigate the post treatment of low-temperature-deposited high dielectric constant (high-k) thin films to enhance their properties. The high-pressure oxygen (O2 and O2+UV light) is employed to improve the properties of low-temperature-deposited metal oxide dielectric films and interfacial layer. In this study, 13nm HfO2 thin films are deposited by sputtering method at room temperature. Then, the oxygen treatments with a high-pressure of 1500 psi at 150 ¢J are performed to replace the conventional high temperature annealing. According to the XPS analyses, integration area of the absorption peaks of O-Hf and O-Hf-Si bonding energies apparently raise and the quantity of oxygen in deposited thin films also increases from XPS measurement. In addition, the leakage current density of standard HfO2 film after O2 and O2+UV light treatments can be improved from 3.12¡Ñ10-6 A/cm2 to 6.27¡Ñ10-7 and 1.3¡Ñ10-8 A/cm2 at |Vg| = 3 V. The leakage current density is significantly suppressed and the current transport mechanism is transformed from trap-assisted tunneling to Schottky-Richardson emission due to the passivation of traps inside HfO2 film and interfacial layer. The proposed treatment is applicable for the future flexible electronics. In the second part of this thesis, we study the memory characteristics of CoSi2 nanocrystals with SiO2 or Al2O3/HfO2 multiple layer tunnel oxide. Due to the property of high-k, it can provide thicker physics thickness than thermal oxide (SiO2) under identical equivalent oxide thickness (EOT) and enhances the reliability without reducing the programming speed. By engineering the different dielectric constant materials and the energy band structure, the performance of nonvolatile memory can be improved. The device that employs HfO2/Al2O3/HfO2 as tunnel oxide exhibits better memory window and carrier injection efficiency than the device employing thermal oxide. Furthermore, the device employs Al2O3/HfO2/Al2O3 as tunnel oxide present the better retention characteristics than the device employs HfO2/Al2O3/HfO2 as tunnel oxide. The corresponding mechanisms were also discussed. For the advanced nonvolatile application, high-k material - hafnium oxide was applied on the resistance switching nonvolatile memory device as resistive switching layer with TiN/Ti/HfO2/TiN structure in the third part of this thesis. By using a thin Ti layer as the reactive buffer layer into the anode side, the proposed device exhibits superior bistable characteristics. Since the Ti can easily absorb oxygen atoms from buried HfO2, the TiN/Ti bi-layer can greatly improve the resistive switching characteristics. The mechanism of the proposed device is dominated by the redox reaction between the Hf and HfOX. In addition, the proposed device has multi-bit storage ability to enhance the storage density. From the temperature-dependent measurements, the low ambient temperatures would cause the formation and rupture of the conduction path with discordant quality and quantity during every switching cycle, which give rise to a wide distribution of the HRS and LRS resistance and instability of resistive switching properties. In the fourth part of this thesis, we investigate the characteristics of an advanced Cu-induced resistance switching non-volatile memory with Pt/Cu/SiON/TiN/SiO2/Si structure. By inserting a Cu ultra thin film between the SiON layer and Pt top electrode, the device exhibits bipolar resistive switching characteristics after a forming process at 13.6 V. However, the forming and resistive switching process can not be observed in the device if the Cu thin film is omitted. Additionally, we employ a two-step forming process to reduce the forming voltage to 7.5 V. During the forming process, the bias-induced Cu could form a filament-like stretched electrode, but the ¡§set¡¨ and ¡§forming¡¨ voltage of the proposed device take place on different polarity. Therefore, we suppose a bipolar switching mechanism, and our device is dominated by the formation and rupture of the oxygen vacancies in a conduction path between the Cu filament and TiN button electrode. The device also demonstrates stable resistance states during 105 cycling bias pulse operations and acceptable retention characteristics after an endurance test at 85¢J. The I-V switching curves are analyzed to realize the carrier transport mechanisms in different bias regions and resistance states. Additionally, the effective thickness of the resistance switching layers (deff) for the samples with different SiON thickness is also extracted from the related mechanism and demonstrated that the deff is independent with the initial SiON thickness. The corresponding mechanisms and the deff verify the bipolar switching is dominated by the formation and rupture of the oxygen vacancies in conduction path between Cu filament and TiN bottom electrode.

The resistance random access memory (RRAM) is one of the most popular of the next generation memories with the high operating speed, reliability and the smallest miniature size. RRAM has metal-insulator-metal structure that can greatly reduce the difficulty of entry, but the biggest problem is how to choose the insulator. We selected silicon-based materials to match the intergrated circuits manufacturing process. In this work, sputtering titanium doping in the silicon oxide thin film has a stable characteristic of resistance switching. By material analyzing, we found that supercritical carbon dioxide fluid (SCCO2) treatment can passivate the silicon oxide defect and the self-reduction of titanium oxide, but it also brought OH group into our thin film. So we observed the interface type characteristic of resistance switching. Using constant voltage sampling experiment extract the reaction rate constant (k) and the active energy, prove that the reaction is caused by OH injection. Double-layer structure with titanium-doped and carbon-doped silicon oxide RRAM promote lower operating current by hopping conduction, which is caused by graphite oxide doping. The Space-Charge Limited Current mechanism for high limited current is proven by COMSOL electric field simulation.

Research in nanoparticle-reinforced composites is predicated by the promise for exceptional properties. However, to date the performance of nanocomposites has not reached its potential due to processing challenges such as inadequate dispersion and patterning of nanoparticles, and poor bonding and weak interfaces. The main objective of this dissertation is to improve the physical properties of polymer nanocomposites at low nanoparticle loading. The first step towards improving the physical properties is to achieve a good homogenous dispersion of carbon nanofibers (CNFs) and single wall carbon nanotubes (SWNTs) in the polymer matrix; the second step is to manipulate the well-dispersed CNFs and SWNTs in polymers by using an AC electric field. Different techniques are explored to achieve homogenous dispersion of CNFs and SWNTs in three polymer matrices (epoxy, polyimide and acrylate) without detrimentally affecting the nanoparticle morphology. The three main factors that influence CNF and SWNT dispersion are: use of solvent, sonication time, and type of mixing. Once a dispersion procedure is optimized for each polymer system, the study moves to the next step. Low concentrations of well dispersed CNFs and SWNTs are successfully manipulated by means of an AC electric field in acrylate and epoxy polymer solutions. To monitor the change in microstructure, alignment is observed under an optical microscope, which identifies a two-step process: rotation of CNFs and SWNTs in the direction of electric field and chaining of CNFs and SWNTs. In the final step, the aligned microstructure is preserved by curing the polymer medium, either thermally (epoxy) or chemically (acrylate). The conductivity and dielectric constant in the parallel and perpendicular direction increased with increase in alignment frequency. The values in the parallel direction are greater than the values in the perpendicular direction and anisotropy in conductivity increased with increase in AC electric field frequency. There is an 11 orders magnitude increase in electrical conductivity of 0.1 wt% CNF-epoxy nanocomposite that is aligned at 100 V/mm and 1 kHz frequency for 90 minutes. Electric field magnitude, frequency and time are tuned to improve and achieve desired physical properties at very low nanoparticle loadings.

Most engineering as well as pavement materials are composites composed of two or more components to obtain a variety of solid properties to support internal and external loading. The composite materials rely on physical or chemical properties and volume fraction of each component. While the properties can be identified easily, the volume fraction is hard to be estimated due to the volumetric variation during the performance in the field. Various test procedures have been developed to measure the volume fractions; however, they depend on subjective determination and judgment. As an alternative, electromagnetic technique using dielectric constant was developed to estimate the volume fraction. Empirical and mechanistic approaches were used to relate the dielectric constant and volume fraction. While the empirical models are not very accurate in all cases, the mechanistic models require assumptions of constituent dielectric constants. For those reasons, the existing approaches might produce less accurate estimate of volume fraction. In this study, a mechanistic-based approach using the self consistent scheme was developed to be applied to multiphase materials. The new approach was based on calibrated dielectric constant of components to improve results without any assumptions. Also, the system identification was used iteratively to solve for dielectric parameters and volume fraction at each step. As the validation performed to verify the viability of the new approach using soil mixture and portland cement concrete, it was found that the approach has produced a significant improvement in the accuracy of the estimated volume fraction.

There are many novel techniques have been invented to provide high-data rate with high quality communication services for future wireless communications systems. Recently, a novel digital modulation technology for multiple accesses, referred to as the Multi-Carrier Code Division Multiple Access (MC-CDMA), has been proposed to support high data rate transmission; it is based on the combination of CDMA and orthogonal frequency division multiplexing (OFDM). The MC-CDMA has been shown to be an effective technique for combating multipath fading. With MC-CDMA system, a user¡¦s spreading code can be modulated on separate subcarriers, undergo frequency-flat fading channel and offers frequency diversity advantage. But in a multi-user environment, othogonality among spreading codes is severely distorted due to multipath delay spread, such that the system capacity will be limited by the multiple access interferences (MAI). Similar situations exist due to possible narrowband interference (NBI) from other systems. Effective interference reduction will render system capacity to increase, which means interference suppression techniques are vital in improving overall system performance. In this thesis, we propose a new linearly constrained recursive least square algorithm, with diagonal loading approach, referred to as the DL-LC RLS algorithms, to further improve the system performance. The proposed diagonal loading RLS algorithm is different from conventional diagonal loading RLS algorithm, in which the diagonal loading was used to improve the robustness to pointing errors in beamforming problem. However, in this thesis, the diagonal loading approach could be used to alleviate the effect due to multiple access interference (MAI), such that under certain circumstances, better performance could be achieved. Basically, in the proposed algorithm, the power of interference plus noise of received signal will be estimated and subtracted from the diagonal terms of the autocorrelation matrix of received signal. After that instead of using the original autocorrelation matrix, the new correlation matrix, with subtracting power related to the interference plus noise, will be involved during the adaptation processes for updating the weights of the multi-user detector. Finally, computer simulation results, in terms of bit error rate, are used to demonstrate the merits of the proposed scheme compared with the conventional RLS algorithm approach without using the diagonal approaches.

Virtue is the way to conduct oneself and is the develop guidance and the behavioral principle that lead the people of the past, present, and future to fulfill morals. Decency, well-being, and happiness are the ultimate goals that people seek and are the standards for people to discuss and define behaviors. Therefore, the reason that the becoming of moral people through fulfilling decency is that decency is itself the truth and the highest value among all existences. Decency itself is the concept for all concepts described by Plato, and is spiritual in the rational world. Mankind should avoid being blinded by physical or material values when pursuing values, and should position such pursuing within the spiritual life and metal happiness. Aristotle, however, believes that while a natural person transforms to a moral person, individual¡¦s utmost decency should be dominated by group¡¦s utmost decency. After modern liberalism has prevailed, Hobbes sees human ethics are based on jungle justice, and the evil among interpersonal relationship requires organizing a strong and powerful society to protect oneself and development. Organizing of such society shall break the traditional ethics to establish modern ethics. Despite Locke sees ethics and decency are social customs and compliance of laws, but social customs and laws are not the base, which should be interests and natural rights because interests and natural rights are the foundation, on which the developments of social customs and laws are based. These fundamental base for moral principles is established under free will, and because of mankind¡¦s freedom, ethical behaviors, social responsibilities, and public welfare are developed. Kant, however, believes that virtue comes from primarily good will and sets its position on utmost decency and all values are under utmost decency. Moral principles are, on the other side, unparalleled order, which is absolute, pervasive, and unconditional. Constant says that despite there is difference between freedom of the people of the past and the freedom of the people of present time, but the freedom of the people of the past may not be denied entirely or yearned for because the era now is an open society. Freedom of the past and freedom of present time are equally important. Miller believes that there is not just quantitative difference in happiness, but also qualitative difference. That is, spiritual happiness if far beyond physical happiness. Spiritual happiness is difficult to satisfy and physical happiness is easier to satisfy. Therefore, people who seek for spiritual happiness have stronger pride and do not wish for perish. Hayek says social order is a self-initiated and volunteer order, rather than constructed organized order. Therefore, every person should obey rules for common and righteous behaviors. Such system rules are formed naturally while people interact with each other. Rawls sees justice as the priority decency for social system and is the guiding principle for a society. If ethic does not match with truth, then it must be abandoned or revised. Principles of justice must be constructed from pure procedural justice. Thus it can be seen that the moral and decency of the philosophers listed herein can be concluded that there will be no moral if there is no freedom.

The direct sequence (DS) code division multiple access (CDMA) is one of the most promising multiplexing technologies for wireless communications. It is also a core technology used in the wideband CDMA (WCDMA) system for the third generation (3G) wireless communication systems. In practice, in the CDMA systems the incomplete orthogonal of the spreading codes between users may introduce the so-called multiple access interference (MAI). Usually, the near-far problem exists when the interfering users are assigned powers much higher than the desired user. Such that the system performance might degrade, dramatically, and thus limits the system capacity. To circumvent the above-mentioned problems many effective adaptive multiuser detectors, based on the minimum mean square error (MMSE) and the minimum output energy (MOE) criteria subject to certain constraints have been proposed. In addition, to mitigate multipath fading effect, RAKE receiver was adopted due to the advantages of path diversity, thus, enhances the system performance. To implement the blind adaptive multiuser detector the linearly constrained minimum variance (LCMV), which is the constrained version of MOE, has been suggested. Further, the LCMV-based receivers exhibit high sensitivity to the channel mismatch caused by the unreliable estimation. To deal with this problem the constant modulus (CM) criterion was considered. In this dissertation, to deal with diverse phenomena encountered in practical channels, we first propose new blind adaptive multi-user detectors, based on the Min/Max criterion associated with the LCCM approach. For implementation the LC exponential window (EW) recursive least-square (RLS) algorithm is derived, and is referred to as the EW LCCM-RLS receiver. It can be used to effectively suppress the MAI and ISI, simultaneously, over multipath fading channels and are robust to mismatch problem caused by inaccuracies in the acquisition of timing and spreading code of the desired user. To reduce the complexity of the above-mentioned blind adaptive multi-user receiver with the LCCM-RLS algorithm, the so-called generalized sidelobe-canceller (GSC) structure is adopted, results in obtaining new CM-GSC-RLS algorithm. Moreover, to further improve the system performance for multipath fading and time-varying channel, the sliding window (SW) LCCM-RLS and SW CM-GSC-RLS algorithms are developed. It can be employed for multipath fading channel with the rapidly changing strong narrowband interference (NBI), which is joined suddenly to the CDMA systems. To look more inside the effect of selecting the initial value of the input signals autocorrelation matrix, some theoretical analyses for the SW LC-RLS as well as EW LC-RLS are provided. Since, unfortunately, the LCCM criterion is known to highly depend on the exact knowledge of the desired user amplitude that is not known exactly at receiver. In the final of this dissertation, a novel linearly constrained adaptive constant modulus RLS (LC-ACM-RLS) algorithm for blind DS-CDMA receiver is proposed. With this new proposed LC-ACM-RLS algorithm, the amplitude variation of the desired user, due to changing characteristics of the channel, can be tracked adaptively. Thus, better performance achievement, in terms of output signal-to-interference-plus-noise ratio (SINR) and bit error rate (BER), over the conventional LCCM-LMS and LCCM-RLS algorithms can be expected.

Population dynamics is the dominant branch of mathematical biology. The first model for population dynamics was developed by Thomas Malthus. A more complicated model was developed by Pierre Fran&ccedil / ois Verhulst and it is called the logistic equation. Our aim in this thesis is to extend the models using piecewise constant arguments and to find the conditions when the models have fixed points, periodic solutions and chaos with investigation of stability of periodic solutions.

The performance of outlets under constant head is investigated in this study. Behavior of single outlet is analyzed / subsequently effect of multiple outlets on a single outlet is examined. Parameters taken into account are constant head of water, orifice shape, orifice length, number of open outlets and discharge. The outlet type, which is examined, can be classified as a short tube orifice. Two different orifice diameters and tube lengths are used. Outlets had the diameter, 6.00 and 10.35mm. The ratio of orifice length to diameter (l/d) was 5 and 8. Number of outlets is 5, which are opened in several combinations. A dimensional analysis shows that discharge coefficient, Cd is a function of diameter-length ratio and the Reynolds Number. In this study, high Reynolds Number (2300&lt / Re&lt / 18600) range is examined and the results are compared with the available data in the literature. Furthermore, performance of the group outlets is investigated.

The specific heat Cp has been showed at various temperatures in the literature, which shows a sharp increase labeled as the lambda-transition at the critical temperature. This transition has been observed previously among the phases of solid-nematic-isotropic liquid in p-azoxyanisole (PAA) and anisaldazine (AAD), and among the phases of solid-smectic-cholesteric-isotropic liquid in cholesteryl myristate (CM). In this thesis work, we analyze the experimental data for the temperature dependence of Cp and the thermal expansion alpha_p and also pressure dependence of alpha_p by a power-law formula. From the analysis of pressure dependence of alpha_p, we calculate the temperature dependencies of specific heat Cp and of the isothermal compressibility kappa_T for the phase transitions considered in PAA, AAD and CM. Our calculations for the temperature dependence of the p and kappa_T can be compared with the experimental data when available in the literature. Polarization, tilt angle and the dielectric constant have been reported in the literature at various temperatures close to the solid-smectic C*-smectic A-isotropic liquid transition in the ferroelectric liquid crystals of A7 and C7. The mean field model with the free energy expanded in terms of the order parameters (polarization and tilt angle) has been reported in the literature previously. In this thesis work, we apply the mean field model first time by fitting the expressions derived for the temperature dependence of the polarization, tilt angle and the dielectric constant to the experimental data for A7 and C7 from the literature. Since the mean field model studied here describes adequately the observed behaviour of A7 and C7, the expressions for the temperature dependence of the polarization, tilt angle and the dielectric constant which we derive, can also be applied to some other ferroelectric liquid crystals to explain their observed behaviour.