The participation of irrigation districts (IDs) in surface water transfers from agriculture-to-municipal uses is studied by examining IDs’ economic and political behavior, comparing their performance with non-districts (non-IDs), and analyzing the role of economic and demographic heterogeneities in water transfers. Economic modeling, econometric, and analytical techniques are used to investigate these issues. An economic model is developed to investigate how the collective-type institutional structure of IDs in the presence of local interdependencies (between internal water delivery and external water transfers) and increasing returns to scale in the internal water delivery causes reduction in marginal benefit of water transfers and the optimal transfers. The model is also used to investigate how the involvement of the U.S. Bureau of Reclamation in IDs causes more water uses in agriculture availing less for external transfers. The conjunction of multiple uses and exclusion rights without ownership rights in IDs’ water and vote-maximizing political structure of IDs are found to create disincentive for water conservation and transfers. Water transfer responses of IDs and non-IDs are empirically investigated by using a Quasi Maximum Likelihood Estimation (QMLE) technique. Based on the analysis of 38 years of time series water transfer data, IDs are found to be less responsive in water transfers relative to non-IDs in terms of water right-weighted transfers. It is found that water scarcity, private housing permits, and nonfarm establishments are positively associated with water transfers. The marginal effect of water scarcity on water transfer is stronger for non-IDs than for IDs. Impacts of economic and demographic heterogeneities on water transfer behavior of IDs are investigated using unbalanced panel data econometric techniques. Water right holdings and population in nearby cities of IDs are found to be significantly correlated with water transfer behaviors of IDs. Larger IDs with higher water right holdings and higher population centers in nearby cities are found to be more responsive to water transfers. The findings complement previous studies that commend public attention for policy redesign including institutional changes to motivate IDs to increase their water transfer activity.

In longitudinal studies, the exact timing of an event often cannot be observed, and is usually detected at a subsequent visit, which is called interval censoring. Spacing of the visits is important when designing study with interval censored data. In a typical longitudinal study, the spacing of visits is usually the same across all subjects (balanced design). In this dissertation, I propose an unbalanced design: subjects at baseline are divided into a high risk group and a low risk group based on a risk factor, and the subjects in the high risk group are followed more frequently than those in the low risk group. Using a simple setting of a single binary exposure of interest (covariate) and exponentially distributed survival times, I derive the explicit formula for the asymptotic sampling variance of the estimate for the covariate effect. It shows that the asymptotic sampling variance can be simply reduced by increasing the number of examinations in the high risk group. The relative reduction tends to be greater when the baseline hazard rate in the high risk group is much higher than that in the low risk group and tends to be larger when the frequency of assessments in the low risk group is relatively sparse. Numeric simulations are also used to verify the asymptotic results in small samples and evaluate the efficiency of the unbalanced design in more complicated settings. Beyond comparing the asymptotic sampling variances, I further evaluate the power and empirical Type I error from unbalanced design and compare against the traditional balanced design. Data from a randomized clinical trial for type 1 diabetes are further used to test the performance of the proposed unbalanced design, and the parametric analyses of these data confirmed the findings from the theoretical and numerical studies.

If the rotor of an induction motor is not concentric with the stator then an electromagnetic force is generated in a direction that will increase the eccentricity. This is called unbalanced magnetic pull (UMP). The first part of the work presented in this dissertation develops theoretical models which allow the calculation of the UMP in cage induction motors due to static rotor eccentricity. These account for any winding configuration including parallel stator winding connection. The second part of the work verifies the models experimentally using two different cage induction motors. The agreement between predicted and measured values of UMP and line current is found to be good. The investigation leads to several new aspects of the damping effects of parallel stator windings and the cage rotor being highlighted.

Let S ⊆ V be an arbitrary subset of vertices of a graph G = (V,E). The differential ∂(S) of S equals the difference between the number of vertices in V \ S that are adjacent to vertices in S and the number of vertices in S. A nonempty set S is called a balanced set if ∂(S) = 0. In this paper we introduce the study of balanced sets in graphs. Not all graphs have balanced sets, and such graphs are called unbalanced. We give proofs of the existence of balanced sets in various kinds of graphs, such as even order graphs, bipartite graphs, and graphs of maximum degree three. We also investigate unbalanced graphs.

This paper considers the estimation of the components of variation for a two-factor unbalanced nested design and compares standard techniques with proposed approximation procedures. Current procedures are complicated and assume the unbalanced sample size to be fixed. This paper tests some simpler techniques, assuming sample sizes are random variables. Monte Carlo techniques were used to generate data for testing of these new procedures.

Prior research confirms that the number of men in a population is associated with elevated levels of crime. The connection between higher numbers of males relative to females and crime is far less studied in larger aggregate populations, and the nature of the relationship is less clear. This study seeks to answer three questions: are unbalanced sex ratios associated with crime at the state level? At what level does the skew begin to matter? How quickly is the impact observed? These questions are examined through analysis of a novel longitudinal dataset of social characteristics and crime indicators for frontier American states between 1850 and 1920. Fixed effects longitudinal analysis reveals a positive association at the state level between skewed sex ratios - towards both men and women - and crime. This study concludes that any deviation from an equal sex ratio is associated with higher levels in crime, and this impact was demonstrated to occur within a short time frame.

In today’s digital era, establishing an online presence and maintaining a well-structured website is vitalfor companies to remain competitive in their respective markets. A crucial aspect of online success liesin strategically selecting the right words to optimize customer engagement and search engine visibility.However, this process is often time-consuming, involving extensive analysis of a company’s website aswell as its competitors’. This thesis focuses on developing an efficient binary classification approachto identify key words and phrases extracted from multiple company websites. The data set used forthis solution consists of approximately 92,000 scraped samples, primarily comprising non-key samples.Various features were extracted, and a word embedding model was employed to assess each sample’srelevance to its specific industry and topic. The logistic regression, decision tree and random forestalgorithms were all explored and implemented as different solutions to the classification problem. Theresults indicated that the logistic regression model excelled in retaining keywords but was less effectivein eliminating non-keywords. Conversely, the tree-based methods demonstrated superior classificationof keywords, albeit at the cost of misclassifying a few keywords. Overall, the random forest approachoutperformed the others, achieving a result of 76 percent in recall and 20 percent in precision whenpredicting key samples. In summary, this thesis presents a solution for classifying words and phrasesfrom company websites into key and non-key categories, and the developed methodology could offervaluable insights for companies seeking to enhance their website optimization strategies.

In this thesis first the behavior of induction generators under unbalanced voltage conditions is studied. In this context, first the existing schemes for characterizing the unbalance in simple ways have been studied. The two schemes IEC, NEMA which are in use to quantify the unbalance, as an unbalance factor require the use of complex algebra. A new scheme to characterize voltage unbalance, without using any complex algebra has been proposed and its effectiveness is compared with the NEMA scheme. The performance of the induction generators under unbalanced voltage conditions is first studied using the symmetrical component approach and a detailed simulation. The machine currents for the same unbalanced conditions are estimated using the proposed scheme and its effectiveness is highlighted. Existing approximate schemes based on unbalance factor do not consider the phase differences between positive and negative sequence voltages while estimating currents. A method of including this feature is proposed here. A simple way to find the maximum line current among the three phases as a function of the positive and negative voltages has been proposed. Knowing the positive, negative sequence voltages and the angle between them, a scheme to compute the generator currents under unbalanced conditions is proposed. Finally a few affecting the machine heating due to unbalanced currents have been studied. The nature of the induction generator fault currents is studied to understand their implication on the system performance. First the fault currents that have been recorded from experiments on relatively small induction motors(26kW and 122kW) are compared with those obtained through detailed dynamic simulation, in order to validate the usage of the detailed dynamic simulations to study the fault current behavior of the induction machines in the absence of experimental or field records. In order to assess the impact of error in the measured machine parameters on the estimated fault current values, the sensitivity of the estimated values of fault currents to machine parameter variations is investigated. The fault currents in large grid connected induction generators (3MW to 500kW) have been estimated through detailed simulation. The effect of the instant of fault (w.r.t voltage cycle), input load levels and shunt capacitors on the fault current values is investigated. An eigen value analysis of the generator model has been carried out to understand the reasons for the observed behavior using the linearized machine model. Fitting functions have been adopted to quantify the fault currents, in order to facilitate comparison of fault currents. A method of including induction generators into the system fault studies has been proposed. Methods of choosing proper sequence impedances for representing the induction generator have been developed and validated using simulated values of balanced and unbalanced fault currents. Simulations of self excited generators have been used for determining the unbalanced fault currents, so as to ensure that the induction generator fault currents correspond to only those contributed by the machine. The impact of the induction generators penetration on the short circuit levels is investigated considering a 14 bus test system by incorporating the proposed induction generator models in a system level fault study.

Economical constraints on the design of bridges usually necessitate the use of as few girders as possible across the bridge width. The girders are typically uniformly spaced transversely with the deck extending past the fascia girders, thereby resulting in an overhang. While designers commonly employ rules of thumb with regard to the geometry of the overhang, these rules of thumb generally lack research justification and the actual girder behavior is not well understood. Overhang construction often produces torsinally unbalanced loading on the girder system, which can lead to problems in steel and concrete girder bridges during construction. The main issue with concrete girder bridges is excessive lateral rotation in the fascia girder, which can cause potential problems of construction safety and maintenance. Field problems on concrete bridges have been reported in the state of Texas where the fascia girders experienced excessive rotation during construction. For steel girder bridges, the unbalanced overhang loading can lead to both local and global instability. Locally, the overhang brackets often exert a large force on the web plate that can distort the web and increase the magnitude of the plate imperfection. Global stability problems have also occurred primarily on bridge widening projects when a few girders are added to an existing bridge system. The girders in the widening are usually isolated from the existing bridge and the unbalanced load from the overhang can cause excessive twist that intensifies the global stability of the girder system. The objective of this study was to improve the understanding of the bridge behavior due to the unbalanced loading from the overhangs and to identify critical factors affecting the girder behavior. The study was also aimed at developing simple design methodologies and design recommendations for overhang construction. The research included field monitoring, laboratory tests, and parametric finite element analyses. The data from the field monitoring and laboratory tests were used to validate finite element models for both concrete and steel girder bridges. Based on the validated models, detailed parametric studies were conducted to investigate the effects of the unbalanced loading. Results from the parametric studies were used to identify the geometries of girder systems that are prone to problems with the overhangs as well as to provide design suggestions. In addition, a closed-form solution for lateral rotation in the fascia girder in a concrete girder bridge was derived using a rigid-body model, and was used to develop design methodology and design recommendations for overhang construction. / text

In this study, a total of twelve beams continuous over two spans of 2,800 mm each were constructed and tested to failure. The beams were divided into two series. Series 1 included six T-beams under symmetrical loading, while Series 2 dealt with six rectangular beams under unsymmetrical loading conditions. In Series 1, the test variables included material type, assumed percentage of moment redistribution, spacing of lateral reinforcement in flange, arrangement of shear reinforcement, and serviceability requirements. In Series 2, three different loading cases were considered, I) loading both spans equally, II) loading both spans maintaining a load ratio of 1.5 and III) loading one span only. Under the loading case II, the parameters of reinforcing material type, assumed percentage of moment redistribution and serviceability requirements were investigated. The test results of both series showed that moment redistribution from the hogging to the sagging moment region took place in GFRP-RC beams which were designed for an assumed percentage of moment redistribution. In Series 1, the decrease of the stirrups spacing from 0.24d to 0.18d enhanced the moment redistribution percentage. Also, decreasing the spacing of lateral reinforcement in the flange from 450 to 150 mm improved the moment redistribution through enhancing the stiffness of the sagging moment region. In Series 2, the unsymmetrical loading conditions (loading case II and III) reduced the moment redistribution by reducing flexural stiffness in the heavily loaded span due to extensive cracking. Regarding serviceability in both series, the GFRP-RC beam designed for the same service moment calculated from the reference steel-RC beam, was able to meet the serviceability requirements for most types of the structural applications. / February 2017