ABSTRACT AS-4 carbon fibers reinforced polyetheretherketone (PEEK) composite materials have been widely used in aerospace industry because of longer fatigue life, high specific stiffness and strength. The thesis is aimed to investigate the residual strength, residual stiffness and mechanical properties of thermoplastic AS-4/PEEK composite laminates subjected to tension-tension (T-T) cyclic loading at room temperature. We adopt modified diaphragm forming method by controlling temperature, pressure, vacuum and time conditions according to the obtained beast curing process to form composite laminates of low crystallinity, transcrystallinity and good fiber / matrix interfaces. Two common type of laminates are used, such as cross-ply [0/90]4S and quasi-isotropic [0/+45/90/-45]2S. Static tension test is performed to measure the elastic modulus and ultimate strength. And T-T fatigue test is conducted with maximum stress of 60% and 80% ultimate strength to find the residual strength and stiffness. Then, through the observation of failure surfaces of composite laminates we understand the failure initiation and mechanism by Scanning Electron Microscope (SEM). The results of experiment can be concluded as follows. The ultimate strength, elastic modulus and fatigue strength of cross-ply composite laminates are larger than those of quasi-isotropic. As centrally notched, the net area of the specimen is reduced, the ultimate strength and fatigue strength of composite materials are lower. The residual strength, adopted to describe the damage process, is monotonically decreasing with increasing of applied cycles. It is found that the residual strength of cross-ply laminates is larger than that of quasi-isotropic laminates. However, the residual stiffness has little change with increasing of applied cycles.

ABSTRACT Hydrophobic organic pollutants (HOPs) are in general characterized by high toxicity, long environmental half-life and high bio-accumulation factors. Due to their hydrophobicity, HOPs tend to sorb onto particles in environment. The influence of the dissolved organic matters (DOMs) on the sorption partition coefficient is observed because of their interactions with HOPs. This binding between DOM and HOPs increases apparent solubility and mobility of the HOPs in natural aquatic system. On the purpose of obtaining data closer to the real world, many aquatic factors, such as the concentration and types of DOM, pH value and ionic strength, are studied intensively recently. There are many studies about the mechanisms in the association of DOM and HOPs. Most of them assume achievement of equilibrium in their measurement. Recently, it was reported (Engebretson and von Wandruszka, 1998) that slow, revering, and even oscillating kinetics are observed. It is great concern and interest to those related studies in literatures. Complicated kinetic may in fact be a cause of the reproducibility problems for measurements of HOPs associated with both humic acid and metals. As such, by monitoring fluorescence intensity, we investigate the equilibrium kinetic of pyrene in HA solutions. In this study, results show that there are two stages of the fluorescence intensity after pyrene spiked into HA solutions: First, the fluorescence intensity decreases steeply due to the first dispersion of pyrene and the reaction of pyrene and HA (the front is dominance). Secound, fluorescence intensity decreases gently because of wall-effect. The dispersion rate of pyrene in HA solutions is difference with HA molecular size and quantity. As the ionic strength rising, cations reacting with specific binding sites on HA, the molecules¡¦ configuration of HA is changed, and less obstruct for dispersing of pyrene. It works as well as little molecular quantity. For second stage when ionic strength rising, wall- associations is less because of the hydrophobic-binding of pyrene and LHA is more stronger. Furthermore, it is not observed the ¡§migration¡¨ of Mg2+ within the LHA molecular structure as described by Engebretson and von Wandruszka .The reasons that make different results may depend on the species of humic acid. Therefore, the observations of Engebretson and von Wandruszka could not be used directly questioning those results in literatures. In addition, the effects of various cations (Mg2+, Ca2+and Sr2+) on Kdom are studied. It is believed different cation reacts with different specific binding sites on HA. As such, both charge density and affinity of cation with specific binding sites on HA should be considered in discussing the effects of metal ionic on the binding constants between PAHs and DOM.

ABSTRACT In this study, two chemical mechanical polishing (CMP) wastewaters were treated by crossflow electro-microfiltration. Also studied are the effects of operation parameters on their treatment efficiencies. In the semiconductor industry, presently, CMP has become the key technique to provide global planarization on interlevel dielectrics (ILD) and metal layers of wafers. In general, the post-CMP cleaning process will produce a great quantity of CMP wastewater. Normally, CMP wastewater consists of abrasives of high concentration and stability, chemicals (e.g., oxidant and surfactant), and a tremendous mass of de-ionized water. Because of the negatively charged suspended solids in CMP wastewater, crossflow electro-microfiltration was used to treat this type of wastewater. By applying an electric field to the system, the negatively charged suspended solids were expelled from the membrane surface moving toward the anode. Not only reducing the cake formation on the membrane, enhancement of the filtration rate and permeate flux have also been found when an external electric field is applied to the filtration system. In this investigation, CMP wastewaters obtained from wafer fabs A and B were first characterized by various standard methods. In CMP wastewater A, the suspended solids were found to have a high negative zeta potential, about ¡V78 mV. Its electrical conductivity was determined to be 127.2 £gS/cm. Before testing, each CMP wastewater was pre-filtered using a filter paper of 1.2 £gm in pore size. An experimental design based on the Taguchi method was employed. The L9 orthogonal arrays were utilized to investigate the effects of four experimental factors ( i.e., electric field strength, crossflow velocity, transmembrane pressure, and membrane pore size) on the filtration rate and permeate quality in the crossflow electro-microfiltration system. When the electric field strength applied was lower than the critical electric field strength, increases of the electric field strength, transmembrane pressure, and membrane pore size were found to be beneficial to the filtration rate. The experimental results were further subjected to the analysis of variance and regular analysis. For both CMP wastewaters A and B, the electric field strength and membrane pore size were determined to be very significant parameters. In this filtration system, the optimal treatment efficiency could be achieved by using a higher electric field strength, lower crossflow velocity, higher transmembrane pressure, and larger membrane pore size. The quality of permeate thus obtained was even better than the tap water quality standards. Therefore, the permeate might be worth recycling for various purposes.

With the coming of knowledge management era, academic institutions also begin to engage in knowledge management (KM) activities, hoping that researchers can understand the relationship between research topics. However, most of the KM activities focusing on academic papers need research¡¦s effort to code and classify paper¡¦s content, and there is still no measurement of relationship between research topics from prior researches. Therefore, this thesis will propose a methodology to measure the relationship between research topics and grab the data of National Central Library from internet to construct a knowledge relationship system. This system will analyze both dissertation¡¦s and thesis¡¦ content, such as keywords, abstracts, etc., and calculate two measurements that are relation strength and relation similarity to assess the direct and indirect relationship between two research topics. Moreover, this thesis found a phenomenon that there is high diversity of Chinese keyword¡¦s usage and the Chinese translation of English keyword. To overcome this incident, the database for Chinese keywords is built. This database will excerpt the mapping of Chinese keywords usage and its translation from the abstract of thesis. Finally, the trend of research topics in information-related domain using different aspects, such as different years, different schools and different departments are analyzed. The result of analysis includes:

Three experiments were conducted to examine the effect of association strength on TOT (tip-of-the-tongue states) and recall. Two hundred nineteen undergraduate students studied pictures and names of 24 imaginary animals that were presented on a large computer screen. The strength of association between the cue and target was manipulated by varying the number of times the picture and the name were presented simultaneously, while keeping the number of presentations for each picture or the target constant across conditions. After the study phase, participants were cued by each picture to recall the imaginary animal names. Participants were asked to rate their strength of TOT on a scale ranging 0 to 3 for each item if they could not think of the name at the moment. Participants also made subjective judgments as to how many times they saw the picture and name of the animal co-occur on the same screen at the study phase, and then they performed a recognition test at the end. The results indicated that the frequency and strength of TOTs linearly increased as a function of number of co-occurrences; the correlation between TOT strength and the participants?? subjective estimation of number of co-occurrences was greater than the correlation between TOT strength and the actual number of co-occurrences. This pattern of results was found even when recall increased along with the increase in number of co-occurrences and was more pronounced particularly when recall was reduced either by interference (Experiment 1) or by increased number of critical items (Experiments 2 & 3) and also by a reduced number of co-occurrence conditions and an increased gap between one level to the next (Experiment 3). Results suggest that an increase in association strength concomitantly increases TOT strength especially when the activation of the target is under threshold for recall and that people may use rules of thumb, or heuristic when they report TOTs by estimating the strength of the cue-target association.

Inspired by promotion of commercial applications, support of location-based services to mobile terminals through their current location has been receiving a lot of attention in recent years even though emergency communications is the primary motivation for development of wireless location. A major challenge to wireless location technique is how to balance the implementation complexity and required accuracy. In the first part of this dissertation, we address one of the fundamental problems in wireless location when using the ToA measurements and develop a simple model to estimate the mobile terminal location with low complexity and promising accuracy. The model employs the geometrical transformation method with single propagation delay measurement. The contribution is that the use of geometrical transformation allows us to overcome the location handover problem, i.e., a forcing handover in a GSM (global system for mobile) network or a three-way soft handover in a UMTS (universal mobile telecommunications system) network. By using the proposed location model, the impact on network performance is kept at the minimum level and the complexity and requirements for hardware and software changes are reduced. In the second part of this dissertation, we address one of the fundamental problems in wireless location when using the SS (signal strength) measurements. The first contribution is to develop a novel wireless location technique based on a ¡§differ- encing¡¨ way, called the SSSD (stationary signal-strength-difference), to remove the uncertainty propagation parameters when merging environment-dependent signal propagation model into the location estimation. This is due to the uncertainty in propagation parameters causes a propagation model error that enlarges error in the distance estimation. The performance gained from the preliminary analysis of SSSD location technique, however, is degraded as a result of the large bias error in the estimated distance and distance difference. To achieve the performance enhancement, the second contribution is to correct the bias error in the estimated distance difference by using a correction method based on a geometric constraint condition. With the corrected distance difference, the final contribution is that we generalized the work on correction method and provide a new framework to correct the error in the estimated distance. As the corrected distance and distance difference is derived by LS (least square) computation, respectively, low computation burden and non-iterative solutions were achieved. To the best of our knowledge thus far, this is first such proposal for a correction to the SS-based location technique. It is demonstrated that the proposed error correction method is shown to perform well when encountering the large error in the estimated distance and distance difference, and prove that the location accuracy can be improved considerably.

Polyimide alignment layer is a very important liquid crystal alignment. The most well-known Liquid crystal display (LCD) alignment methods are homogeneous alignment and homeotropic alignment. This paper research uses different fluff depth and number of rubbing into polyimide,and changes the level of rubbing strength, to observe how electro-optical properties of vertical liquid crystal alignment changes with rubbing strength. By rubbing polyimide with different rubbing strength, this research uses two kind of negative liquid crystal (¡µ£`<0) as samples. This research finds that when rubbing strength increases, the contrast ratio tends to drop.However, the contrast ratio rises after certain level of rubbing strength is applied. Regarding the response time, this research finds that when rubbing strength increases, the response time tends to drop as well. However, the response time rises and falls irregularly after certain level of rubbing strength is applied.

To improve the wire bondability, interfacial adhesion and popcorn cracking resistance in the packaging processing of IC and MEMS chips, this thesis utilized oxygen and helium plasmas to modify and clean the surface of metal pads. The influences of the plasma cleaning time, metal pad materials and wire bonding time/temperature/power on the strength of wire bonding were investigated. Two different wire materials (Al wire with 32 £gm in diameter and Au wire with 25 £gm in diameter) were bonded on the surface of Al, Au and Pt metal pads using a commercial ultrasonic wire bonder (SPB-U688), respectively. The pull strength detection of the implemented micro joints is characterized by an accurate pull strength testing system (Dage SERIES-4000). Based on hundred measurement results, this research has three conclusions described as follows. (I) The pull strength of Au pad is higher than that of Al and Pt pads no matter with the plasma cleaning process or not. The maximum pull strength (12.286 g) can be achieved as the surface of Au pad was modified by the helium plasma for 180 seconds. (II) Helium plasma cleaned wafer can obtain larger improvement of pull strength than that of the oxygen plasma under the same plasma time. However, this result can not be concluded in Al and Pt pads. (III) The optimized wire bonding time/power of the Au, Al and Pt pads are 0.07 s/2.1, 0.05 s/0.6 W and 0.03 s/2.7 W, respectively.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xiii, 148 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 136-137).

Thesis (M.S.) in Forest Resources--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 143-148).