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The failure of longitudinal construction joints is one of the critical factors causing accelerated pavement deterioration. Poor-quality longitudinal construction joints are often characterized by a difference in elevation between adjacent lanes or by unraveling of the hot mix asphalt (HMA). Current wave-based non-destructive testing (NDT) methods are efficient and economical for the evaluation of material properties. In this thesis, an innovative surface wave testing technique for condition assessment of longitudinal construction joints in asphalt pavements is presented. This method enables reduction of the number of cores required for large-strain testing and provision of a more uniform quality assessment of longitudinal joints as well as the relative condition of the asphalt pavements. The technical development is based on a theoretical study of the wave attenuation mechanisms and on the reported deficiencies in current seismic wave-based methods. Traditionally, the use of ultrasonic testing to determine small-strain elastic property for asphalt concrete was uniquely based on the measurement of wave velocity. However, isolated use of wave velocity does not provide complete information of the materials strength because of the different variables that affect the strength-velocity relationship. Therefore, it is necessary to complement velocity data with independent information such as the change in attenuation and frequency content of the propagating pulse. The existing deficiencies in current seismic wave-based methods were addressed to improve reliability, accuracy and consistency for asphalt concrete material characterization in the laboratory and in the field. Refined and improved signal processing techniques were used to overcome the shortcomings in the existing wave-based methods that contribute to uncertainties in the interpretation of test results. To capture more information from a wave, the signal was analyzed in the time and frequency domains. The basic analyses included a simple method such as peak to peak amplitude of the first cycle of arriving wave, and complex methods such as maximum magnitude and area of corresponding frequency spectrum through Fourier transform. A novel approach based on wavelet transform of the signal was presented, which provides an alternative method to determine wave characteristics. Material characterization tests (experiment Phase I) were carried out to study the relationship between the wave characteristics obtained from UPV test and the quality of the asphalt concrete specimens prepared in the laboratory. The specimens were identical in terms of aggregate and asphalt binder ratio, but varying in volumetric properties produced by different compaction efforts. The specimen quality was determined using two methods: 1) the traditional method using density measurement and 2) an innovative approach using dynamic modulus which is recommended by the Federal Highway Administration (FHWA) for use as a fundamental material property for characterizing Superpave mixes (Witczak, et al., 2002; Bonaquist et al., 2003; Christensen et al., 2004). The measured wave characteristics showed excellent correlations (R2 > 0.9) with the fundamental properties of the mix. The results revealed that the wave amplitude parameters as the condition index have the potential to provide a reliable assessment of the quality of HMA mixtures. The finding is very critical to moving the technology forward in the right direction, and form an important basis for the experiment Phase II. Experiment Phase II investigated the feasibility and effectiveness of using the wave characteristics identified in experiment Phase I to assess the condition of longitudinal construction joints. Particular attention was given to examining the sensitivity of the wave-based technique to different types of construction joints. For this purpose, three types of construction joints (good, fair and poor) were fabricated in the laboratory and identified using the wave-based technique. The research was intended to develop a suitable test procedure for condition assessment the longitudinal joints in asphalt pavement in the field. The data from experiment Phase II revealed that the wave-based technique enables assessment of not only the quality of different types of longitudinal construction joints but also the relative condition of asphalt pavements.

The failure of longitudinal construction joints is one of the critical factors causing accelerated pavement deterioration. Poor-quality longitudinal construction joints are often characterized by a difference in elevation between adjacent lanes or by unraveling of the hot mix asphalt (HMA). Current wave-based non-destructive testing (NDT) methods are efficient and economical for the evaluation of material properties. In this thesis, an innovative surface wave testing technique for condition assessment of longitudinal construction joints in asphalt pavements is presented. This method enables reduction of the number of cores required for large-strain testing and provision of a more uniform quality assessment of longitudinal joints as well as the relative condition of the asphalt pavements. The technical development is based on a theoretical study of the wave attenuation mechanisms and on the reported deficiencies in current seismic wave-based methods. Traditionally, the use of ultrasonic testing to determine small-strain elastic property for asphalt concrete was uniquely based on the measurement of wave velocity. However, isolated use of wave velocity does not provide complete information of the materials strength because of the different variables that affect the strength-velocity relationship. Therefore, it is necessary to complement velocity data with independent information such as the change in attenuation and frequency content of the propagating pulse. The existing deficiencies in current seismic wave-based methods were addressed to improve reliability, accuracy and consistency for asphalt concrete material characterization in the laboratory and in the field. Refined and improved signal processing techniques were used to overcome the shortcomings in the existing wave-based methods that contribute to uncertainties in the interpretation of test results. To capture more information from a wave, the signal was analyzed in the time and frequency domains. The basic analyses included a simple method such as peak to peak amplitude of the first cycle of arriving wave, and complex methods such as maximum magnitude and area of corresponding frequency spectrum through Fourier transform. A novel approach based on wavelet transform of the signal was presented, which provides an alternative method to determine wave characteristics. Material characterization tests (experiment Phase I) were carried out to study the relationship between the wave characteristics obtained from UPV test and the quality of the asphalt concrete specimens prepared in the laboratory. The specimens were identical in terms of aggregate and asphalt binder ratio, but varying in volumetric properties produced by different compaction efforts. The specimen quality was determined using two methods: 1) the traditional method using density measurement and 2) an innovative approach using dynamic modulus which is recommended by the Federal Highway Administration (FHWA) for use as a fundamental material property for characterizing Superpave mixes (Witczak, et al., 2002; Bonaquist et al., 2003; Christensen et al., 2004). The measured wave characteristics showed excellent correlations (R2 > 0.9) with the fundamental properties of the mix. The results revealed that the wave amplitude parameters as the condition index have the potential to provide a reliable assessment of the quality of HMA mixtures. The finding is very critical to moving the technology forward in the right direction, and form an important basis for the experiment Phase II. Experiment Phase II investigated the feasibility and effectiveness of using the wave characteristics identified in experiment Phase I to assess the condition of longitudinal construction joints. Particular attention was given to examining the sensitivity of the wave-based technique to different types of construction joints. For this purpose, three types of construction joints (good, fair and poor) were fabricated in the laboratory and identified using the wave-based technique. The research was intended to develop a suitable test procedure for condition assessment the longitudinal joints in asphalt pavement in the field. The data from experiment Phase II revealed that the wave-based technique enables assessment of not only the quality of different types of longitudinal construction joints but also the relative condition of asphalt pavements.

Polymer solar cells are promising in that they are inexpensive to produce, and due to their mechanical flexibility have the potential for use in applications not possible for more traditional types of solar cells. The performance of polymer solar cells depends strongly on the distribution of electron donor and acceptor material in the active layer. Understanding the connection between morphology and performance as well as how to control the morphology, is therefore of great importance. Furthermore, improving the lifetime of polymer solar cells has become at least as important as improving the efficiency.   In this thesis, the relation between morphology and solar cell performance is studied, and the material stability for blend films of the thiophene-quinoxaline copolymer TQ1 and the fullerene derivatives PCBM and PC70BM. Atomic force microscopy (AFM) and scanning transmission X-ray microscopy (STXM) are used to investigate the lateral morphology, secondary ion mass spectrometry (SIMS) to measure the vertical morphology and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to determine the surface composition. Lateral phase-separated domains are observed whose size is correlated to the solar cell performance, while the observed TQ1 surface enrichment does not affect the performance. Changes to the unoccupied molecular orbitals as a result of illumination in ambient air are observed by NEXAFS spectroscopy for PCBM, but not for TQ1. The NEXAFS spectrum of PCBM in a blend with TQ1 changes more than that of pristine PCBM. Solar cells in which the active layer has been illuminated in air prior to the deposition of the top electrode exhibit greatly reduced electrical performance. The valence band and absorption spectrum of TQ1 is affected by illumination in air, but the effects are not large enough to account for losses in solar cell performance, which are mainly attributed to PCBM degradation at the active layer surface. / The performance of polymer solar cells depends strongly on the distribution of electron donor and acceptor material in the active layer. Understanding the connection between morphology and performance as well as how to control the morphology, is therefore of great importance. Furthermore, improving the lifetime has become at least as important as improving the efficiency for polymer solar cells to become a viable technology.   In this work, the relation between morphology and solar cell performance is studied as well as the material stability for polymer:fullerene blend films. A combination of microscopic and spectroscopic methods is used to investigate the lateral and vertical morphology as well as the surface composition. Lateral phase-separated domains are observed whose size is correlated to the solar cell performance, while the observed surface enrichment of polymer does not affect the performance. Changes to the unoccupied molecular states as a result of illumination in ambient air are observed for the fullerene, but not for the polymer, and fullerenes in a blend change more than pristine fullerenes. Solar cells in which the active layer has been illuminated exhibit greatly reduced electrical performance, mainly attributed to fullerene degradation at the active layer surface. / <p>Paper 2 ingick som manuskript i avhandlingen. Nu publicerad. </p>

Doctor of Philosophy / Department of Agronomy / Gary M. Pierzynski / The bioavailability of Pb and Zn is linked to the solubility of solid phases and other soil chemical characteristics, which is associated with their environmental risk, suggesting that in situ stabilization of these elements can be accomplished by influencing their chemistry. However, more research is needed to investigate the effectiveness of different soil amendments on reducing Pb and Zn bioavailability. A lab study was conducted to evaluate the effects of five different P amendments and time on Pb/Zn speciation in a contaminated soil using synchrotron-based techniques, while a field investigation studied the effects of composted beef manure on plant biomass production and the influence on microbial function, size, and community shifts. In the lab study, the Pb-phosphate mineral plumbogummite was found as an intermediate phase of pyromorphite formation, which has not been documented until now. Additionally, all fluid and granular P sources were able to induce Pb-phosphate formation, but fluid phosphoric acid (PA) was the most effective with time and distance from the treatment. However, acidity from PA increased the prescence of soluble Zn species, which can have negative environmental consequences. Granular phosphate rock (PR) and triple super phosphate (TSP) reacted to generate both Pb- and Zn-phosphates, with TSP being more effective at greater distances than PR. In the field study, compost additions of 269 Mg ha[superscript]1 significantly decreased bioavailable Zn, while increasing estimated available water, plant nutrients, and plant biomass as compared to a contaminated control and low addition of compost (45 Mg ha[superscript]1) over three years. Additionally, compost additions of 269 Mg ha[superscript]1 significantly increased microbial enzyme activities, nitrification, and microbial biomass over the contaminated control through the duration of the study. Increases in microbial activity and biomass are related to increases in total C, available water, and extractable P, while negative relationships were found with electrical conductivity and with bioavailable Zn. The addition of lime or lime plus bentonite with compost did not further reduce metal availability, increase plant biomass, or improve the size or function of microbial communities. High compost additions caused a slight shift in microbial community structure according to phospholipids fatty acid analysis. Increases in the mole percents of both Gram-positive (Gm[superscript]+) and Gram negative (Gm[superscript]-) bacteria were found depending on site. Microbial biomass of Gm[superscript]+, Gm[superscript]-, and fungi were also increased by high compost additions. Results indicate that large additions of compost are needed to increase microbial biomass, improve microbial activity, and re-establish a healthy vegetative community. This study proposes that organic matter and P amendments can be used to stabilize and reduce the bioavailability of heavy metals in soils and mine waste materials, but must be managed carefully and intelligently.

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The present thrust in the electronics industry towards integrating multiple functions on a single chip while operating at very high frequencies has highlighted the need for efficient Electronic Design Automation (EDA) tools to shorten the design cycle and capture market windows. However, the increasing complexity in modern circuit design has made simulation a computationally cumbersome task. The notion of model order reduction has emerged as an effective tool to address this difficulty. Typically, there are numerous approaches and several issues involved in the implementation of model-order reduction techniques. Among the important ones of those issues is the problem of determining a suitable order (or size) for the reduced system. An optimal order would be the minimal order that enables the reduced system to capture the behavior of the original (more complex and larger) system up to a user-defined frequency. The contribution presented in this thesis describes a new approach aimed at determining the order of the reduced system. The proposed approach is based on approximating the impulse response of the original system in the time-domain. The core methodology in obtaining that approximation is based on numerically inverting the Laplace-domain of the representation of the impulse response from the complex-domain (s-domain) into the time-domain. The main advantage of the proposed approach is that it allows the order selection algorithm to operate directly on the time-domain form of the impulse response. It is well-known that numerically generating the impulse response in the time-domain is very difficult and its not impossible, since it requires driving the original network with the Dirac-delta function, which is a mathematical abstraction rather than a concrete waveform that can be implemented on a digital computer. However, such a difficulty is avoided in the proposed approach since it uses the Laplace-domain image of the impulse response to obtain its time-domain representation. The numerical simulations presented in the thesis demonstrate that using the time-domain waveform of the impulse response, computed using the proposed approach and properly filtered with a Butterworth filter, guides the order selection algorithm to select a smaller order, i.e., the reduced system becomes more compact in size. The phrase "smaller or more compact" in this context refers to the comparison with existing techniques currently in use, which seek to generate some form of time-domain approximations for the impulse response through driving the original network with pulse-shaped function (e.g., Gaussian pulse).