The Design-Build delivery method has gained popularity in the construction industry in the 21st century among clients seeking singular responsibility, shorter delivery time frame and management of complex works. In this exploratory study, a model that considers the effects of project technical system on the project organisation structure has been proposed. Project technical system comprises of two dimensions: technical uncertainty and technical complexity, while integration, organisational differentiation, information processing and project size were considered as dimensions of the project organisation structure. Several hypotheses linking the relationship between technical uncertainty, technical complexity and project structure has been developed. A self-administered questionnaire was developed as the data collection instrument. Field data were collected from design-build projects in the civil and architectural construction industry in Taiwan, and analysed at the project level. The technical system-structure relationships were tested statistically mainly by multiple regression. Results indicate that various scholarly perspectives of uncertainty have a common underlying construct. Several inter-correlations among components of the technical system were identified, and interactively they affect the project organisation structure. Technical uncertainty was found to be a better predictor of information processing and internal integrative efforts than technical complexity. Less structured and flexible information processes and coordinative mechanisms were favoured under high levels of technical uncertainty and complexity. Technical complexity was found to partially predict organisational differentiation, particularly by the interacting effects of project scope and concurrency. The level of technical staffing could be explained by project scope and technical differentiation of the complexity dimension. Lastly, the results were mixed for technical complexity as a predictor of the extent to which project work is subcontracted. The findings of this study contributed to the understanding of the relationships between technical system and organisation structure in complex Design-Build projects. Various managerial implications were outlined. The model proposed in this study can be extended to include project effectiveness, which may lead to the identification of key structural arrangements that contribute to improved project performance.

This dissertation studies the antecedents and consequences of the flow experience in online retailing environments. Flow is the enjoyable and engrossing experience that people feel when acting with total involvement. A review of previous studies suggests that applying the notion of flow to understand the online consumer experience is a promising but underdeveloped field with several conceptual and methodological issues. This dissertation attempts to contribute to our understanding of flow in online shopping in three ways. First, a three-part validity study was carried out using different approaches to construct validity and involving two sets of two flow measures: the Flow State Scale (FSS, Jackson and Marsh 1996) and the Internet Flow Scale (IFS). The first study related flow to behavioral criteria in online shopping. The second conducted a traditional construct validity study in which we developed and tested a “nomological network” of relationships between flow measures and other logically-related constructs. This study also included a Multitrait-Multimethod validity study. The third was a factorial validity study of the flow construct. These studies provided evidence of construct validity for flow and suggested that the FSS had advantages over the IFS in terms of validity. Second, this dissertation tested a comprehensive model of flow that included the underlying dimensions of flow, the mediating effects of perceived challenge and skill on flow, and antecedents and consequences of flow. Consequences of flow include perceived usefulness, affective responses to the site, and intentions to revisit and purchase. Overall, results based on data collected by a controlled experiment supported our model, suggesting that flow is a second-order construct and positively related to outcome variables. Thirdly, we studied the effect of Web site complexity on flow. Perceived site complexity was found to effect flow negatively. Investigating the effects of it on inducing flow in online shopping may eventually lead us to guidelines for improving the shopping experience by designing more capable Web sites.

Many problems of practical significance are known to be NP-hard, and hence, are unlikely to be solved by polynomial-time algorithms. There are several ways to cope with the NP-hardness of a certain problem. The most popular approaches include heuristic algorithms, approximation algorithms, and randomized algorithms. Recently, parameterized computation and complexity have been receiving a lot of attention. By taking advantage of small or moderate parameter values, parameterized algorithms provide new venues for practically solving problems that are theoretically intractable. In this dissertation, we design efficient parameterized algorithms for several wellknown NP-hard problems and prove strong lower bounds for some others. In doing so, we place emphasis on the development of new techniques that take advantage of the structural properties of the problems. We present a simple parameterized algorithm for Vertex Cover that uses polynomial space and runs in time O(1.2738k + kn). It improves both the previous O(1.286k + kn)-time polynomial-space algorithm by Chen, Kanj, and Jia, and the very recent O(1.2745kk4 + kn)-time exponential-space algorithm, by Chandran and Grandoni. This algorithm stands out for both its performance and its simplicity. Essential to the design of this algorithm are several new techniques that use structural information of the underlying graph to bound the search space. For Vertex Cover on graphs with degree bounded by three, we present a still better algorithm that runs in time O(1.194k + kn), based on an “almost-global” analysis of the search tree. We also show that an important structural property of the underlying graphs – the graph genus – largely dictates the computational complexity of some important graph problems including Vertex Cover, Independent Set and Dominating Set. We present a set of new techniques that allows us to prove almost tight computational lower bounds for some NP-hard problems, such as Clique, Dominating Set, Hitting Set, Set Cover, and Independent Set. The techniques are further extended to derive computational lower bounds on polynomial time approximation schemes for certain NP-hard problems. Our results illustrate a new approach to proving strong computational lower bounds for some NP-hard problems under reasonable conditions.

This dissertation focuses on a comparative study of small-world characteristics in geographical, epidemic, and virtual spaces. Small-world network is the major component of the “new science of networks” that emerged recently in research related to complex networks. It has shown a great potential to model the complex networks encountered in geographical studies. This dissertation, in an attempt to understand the emergence of small-world phenomenon in spatial networks, has investigated the smallworld properties in aforementioned three spaces. Specifically, this dissertation has studied roadway transportation networks at national, metropolitan, and intra-city scales via network autocorrelation methods to investigate the distance effect on the emergence of small-world properties. This dissertation also investigated the effect of small-world network properties on the epidemic diffusion and different control strategies through agent-based simulation on social networks. The ASLevel Internet in the contiguous U.S. has been studied in its relation between local and global connections, and its correspondence with small-world characteristics. Through theoretical simulations and empirical studies on spatial networks, this dissertation has contributed to network science with a new method – network autocorrelation, and better understanding from the perspective of the relation between local and global connections and the distance effect in networks. A small-world phenomenon results from the interplay between the dynamics occurring on networks and the structure of networks; when the influencing distance of the dynamics reaches to the threshold of the network, the network will logically emerge as a small-world network. With the aid of numerical simulation a small-world network has a large number of local connections and a small number of global links. It is also found that the epidemics will take shorter time period to reach largest size on a small-world network and only particular control strategy, such as targeted control strategy, will be effective on smallworld networks. This dissertation bridges the gap between new science of networks and the network study in geography. It potentially contributes to GIScience with new modeling strategy for representing, analyzing, and modeling complexity in hazards prevention, landscape ecology, and sustainability science from a network-centric perspective.

Much research has been done on wireless sensor networks. However, most protocols and algorithms for such networks are based on the ideal model Unit Disk Graph (UDG) model or do not assume any model. Furthermore, many results assume the knowledge of location information of the network. In practice, sensor networks often deviate from the UDG model significantly. It is not uncommon to observe stable long links that are more than five times longer than unstable short links in real wireless networks. A more general network model, the quasi unit-disk graph (quasi-UDG) model, captures much better the characteristics of wireless networks. However, the understanding of the properties of general quasi-UDGs has been very limited, which is impeding the design of key network protocols and algorithms. In this dissertation we study the properties for general wireless sensor networks and develop new topological/geometrical techniques for wireless sensor networking. We assume neither the ideal UDG model nor the location information of the nodes. Instead we work on the more general quasi-UDG model and focus on figuring out the relationship between the geometrical properties and the topological properties of wireless sensor networks. Based on such relationships we develop algorithms that can compute useful substructures (planar subnetworks, boundaries, etc.). We also present direct applications of the properties and substructures we constructed including routing, data storage, topology discovery, etc. We prove that wireless networks based on quasi-UDG model exhibit nice properties like separabilities, existences of constant stretch backbones, etc. We develop efficient algorithms that can obtain relatively dense planar subnetworks for wireless sensor networks. We also present efficient routing protocols and balanced data storage scheme that supports ranged queries. We present algorithmic results that can also be applied to other fields (e.g., information management). Based on divide and conquer and improved color coding technique, we develop algorithms for path, matching and packing problem that significantly improve previous best algorithms. We prove that it is unlikely for certain problems in operation science and information management to have any relatively effective algorithm or approximation algorithm for them.

A celebrated theorem of Savitch [Savitch'70] states that NSPACE(S) is contained in DSPACE(S²). In particular, Savitch gave a deterministic algorithm to solve ST-Connectivity (an NL-complete problem) using O({log}²{n}) space, implying NL (non-deterministic logspace) is contained in DSPACE({log}²{n}). While Savitch's theorem itself has not been improved in the last four decades, several graph connectivity problems are shown to lie between L and NL, providing new insights into the space-bounded complexity classes. All the connectivity problems considered in the literature so far are essentially special cases of ST-Connectivity. In this dissertation, we initiate the study of auxiliary PDAs as graph connectivity problems and define sixteen different "graph realizability problems" and study their relationships. The complexity of these connectivity problems lie between L (logspace) and P (polynomial time). ST-Realizability, the most general graph realizability problem is P-complete. 1DSTREAL(poly), the most specific graph realizability problem is L-complete. As special cases of our graph realizability problems we define two natural problems, Balanced ST-Connectivity and Positive Balanced ST-Connectivity, that lie between L and NL. We study the space complexity of SGSLOGCFL, a graph realizability problem lying between L and LOGCFL. We define generalizations of graph squaring and transitive closure, present efficient parallel algorithms for SGSLOGCFL and use the techniques of Trifonov to show that SGSLOGCFL is contained in DSPACE(lognloglogn). This implies that Balanced ST-Connectivity is contained in DSPACE(lognloglogn). We conclude with several interesting new research directions.

<p>The aim of the thesis is to find out the most suitable channel estimation algorithms for the existing MIMO-OFDM SDR platform. Starting with the analysis of several prevalent channel estimation algorithms, MSE performance are compared under different scenarios. As a result of the hardware independent analysis, the complexvalued matrix computations involved in the algorithms are decomposed to real FLoating-point OPerations (FLOPs). Four feasible algorithms are selected for hardware dependent discussion based on the proposed hardware architecture. The computational latency is exposed as a manner of case study.</p>

This thesis is focused on the limits of performance of large-scale convex optimization algorithms. Classical theory of oracle complexity, first proposed by Nemirovski and Yudin in 1983, successfully established the worst-case behavior of methods based on local oracles (a generalization of first-order oracle for smooth functions) for nonsmooth convex minimization, both in the large-scale and low-scale regimes; and the complexity of approximately solving linear systems of equations (equivalent to convex quadratic minimization) over Euclidean balls, under a matrix-vector multiplication oracle. Our work extends the applicability of lower bounds in two directions: Worst-Case Complexity of Large-Scale Smooth Convex Optimization: We generalize lower bounds on the complexity of first-order methods for convex optimization, considering classes of convex functions with Hölder continuous gradients. Our technique relies on the existence of a smoothing kernel, which defines a smooth approximation for any convex function via infimal convolution. As a consequence, we derive lower bounds for \ell_p/\ell_q-setups, where 1\leq p,q\leq \infty, and extend to its matrix analogue: Smooth convex minimization (with respect to the Schatten q-norm) over matrices with bounded Schatten p-norm. The major consequences of this result are the near-optimality of the Conditional Gradient method over box-type domains (p=q=\infty), and the near-optimality of Nesterov's accelerated method over the cross-polytope (p=q=1). Distributional Complexity of Nonsmooth Convex Optimization: In this work, we prove average-case lower bounds for the complexity of nonsmooth convex ptimization. We introduce an information-theoretic method to analyze the complexity of oracle-based algorithms solving a random instance, based on the reconstruction principle. Our technique shows that all known lower bounds for nonsmooth convex optimization can be derived by an emulation procedure from a common String-Guessing Problem, which is combinatorial in nature. The derived average-case lower bounds extend to hold with high probability, and for algorithms with bounded probability error, via Fano's inequality. Finally, from the proposed technique we establish the equivalence (up to constant factors) of distributional, randomized, and worst-case complexity for black-box convex optimization. In particular, there is no gain from randomization in this setup.

The purpose of this study was to investigate the current perceptions of high school principals regarding their perceived roles, professional development experiences that impacted their careers, and the challenges and frustrations they face when enacting their roles as high school leaders. This qualitative study investigated perceptions of high school principals and addressed three research questions: (1) What are the perceptions of high school principals regarding their role as school leaders? (2) What professional development experiences do high school principals report are most important in impacting their careers? (3) What do high school principals perceive are their greatest challenges and frustrations? Three in-depth qualitative interviews were conducted with each of eight high school principals. The results were based on analysis by the researcher and the two expert panels. The high school principals perceived that they had a tremendous number of roles and responsibilities within their positions. The roles and responsibilities that were identified with the greatest importance were: providing a safe learning environment, ensuring quality teachers and quality instruction, high accountability expectations for all and mandates, and leadership within the school and system. Professional development opportunities and personalized support systems were perceived to be vital to the success of the high school principal.  Principals in the study reported that both formal and informal professional development experiences were beneficial for their improvement as school leaders. The principals perceived that when they created relationships with mentors and established strong networks, they improved the likelihood of sustained support and success. High school principals perceived the greatest challenges were management of time, balancing leadership and management of the school, and navigating the legislative mandates and accountability requirements.  High school principals perceived the greatest frustrations were issues related to time and legislative mandates dictated to them by the local, state, and federal systems. They faced constant pressures that could be directly tied to student achievement and accountability measures. High school principals need to be prepared to assume various roles. Further research may determine if roles and challenges identified by the eight participants mirror other states’ results.

ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / SOQPSK-TG is a highly bandwidth-efficient constant-envelope modulation so that it has been applied in aeronautical telemetry widely. We develop a simple detection of SOQPSK-TG which is based on a modified OQPSK detection. The simple detection has the advantages of low complexity and good performance. And it's also suitable for other varieties of SOQPSK and FQPSK.