<p> Usage of cellular networks for data services is growing rapidly worldwide as more consumers browse the Internet, check emails, and watch videos on smartphones and tablets. To ensure that sufficient capacity is available on cellular and wireless networks, current utilization of the radio spectrum, an encumbered and finite resource, needs to be evaluated. Spectrum is usually made available by governmental regulatory bodies through auctions. From a policy and regulatory perspective, auctions of spectrum try to ensure the efficient use of spectrum by allocating it to the entities that value it the most. Auctions also generate revenues for governments. Cellular operators worldwide have been asking for allocation of more spectrum for cellular networks to support the growing demand of mobile data services. Perception of radio spectrum scarcity has been linked, sometimes linearly, to the higher demand of mobile data services and the greater market penetration of mobile broadband devices. To validate the "spectrum scarcity" notion, various elements of the wireless ecosystem, including network infrastructure, spectral efficiency of mobile technologies, and data offloading via unlicensed spectrum need to be appraised; and their effects on "spectrum utilization" need to be understood. Research presented here takes a system dynamics approach to study dynamic behavior among these elements and their effects on usage of spectrum through computer-based simulation. System dynamics provides a powerful means to model a complex system comprised of dependent and independent variables. With the help of the Causal Loop Diagram, we explain the research framework and formulate the hypotheses. A stock-and-flow model-based simulation is employed for hypotheses testing to justify the need for more spectrum. Dynamic behavior among different variables of the wireless ecosystem is also analyzed through this simulation. The study conducted here also explains why system dynamics appears to be a comprehensive approach to address the wireless industry's spectrum scarcity and utilization problem. Simulation results show that mobile data demand can exceed the current capacity of cellular networks causing a spectrum deficit if apt planning of spectrum policies and appropriate infrastructure investment are delayed.</p>

<p> This study explores whole system design and evolutionary 21st century American buildings + infrastructure. The ideas and findings of this dissertation research, as presented at the Seventh International Conference on Design Principles and Practices in Chiba, Japan on March 6, 2013, are provided in a forthcoming publication by the authors (Franz, Sarkani, and Mazzuchi 2013). </p><p> Since the introduction of the theory of ecological design in the mid-1970s, whole system design, based on collaboration, research, new technologies and iterative value management, has been increasingly applied to drive sustainable and more innovative solutions (Franz 2011, 2012). While this systems engineering approach for achieving substantial environmental and economic benefits is more commonplace today, it is theorized that evolutionary buildings + infrastructure are achieved through an expanded model of whole system design, one combining art and science, and disciplined processes for the purpose of innovation and differentiation (Franz, Sarkani, and Mazzuchi 2013). This model integrating whole system design (integrated design) with project management, systems engineering process models and radial innovation drives design innovation, promotes change in the built environment and prompts new market opportunities for the Architect Engineer and Construction industry (Franz, Sarkani, and Mazzuchi 2013). </p><p> Franz, Sarkani, and Mazzuchi (2013) note that understanding critical success factors for producing distinguished projects is key to sustaining architectural and engineering practice and the building industry. Through quantitative measurement and qualitative case study analyses, the study using winning projects from <i>Engineering News Record's</i> (ENR) Best of the Best 2011 Project Awards (as announced on February 13, 2012 in ENR, The 2011 Best of the Best Projects) examines four questions: 1) what are critical success factors for producing evolutionary 21^st century buildings + infrastructure? 2) does whole system design enable project success? 3) do systems engineering process models enhance whole system design? and 4) is radical innovation critical for producing evolutionary American buildings + infrastructure? (Franz, Sarkani, and Mazzuchi 2013) </p><p> The study indicates that significant evidence exists to support prior research for factors related to people, project activities, barriers and success (Germuenden and Lechler 1997), and that whole system design (Coley and Lemon, 2008, 2009; Charnley, Lemon and Evans, 2011), as implemented through systems engineering process models (Bersson, Mazzuchi, and Sarkani 2012), and radical innovation (Norman and Verganti 2011) additionally are important factors. Case study information suggests that buildings + infrastructure evolve through design innovation, enhanced by an expanded model for whole system design aligning goals, vision, whole system design and outcomes (Franz, Sarkani, and Mazzuchi 2013). The study informs professionals and students about design innovation and effective project delivery strategies strengthened through systems engineering (Franz, Sarkani, and Mazzuchi 2013). </p><p> <i>Keywords: Critical Success Factors, Whole System Design, Systems Engineering, Radical Innovation.</i></p>

<p> Magnetic nanoparticle hyperthermia (mNPH) is an emerging cancer therapy which has shown to be most effective when applied in the adjuvant setting with chemotherapy, radiation or surgery. Although mNPH employs heat as a primary therapeutic modality, conventional heat may not be the only cytotoxic effect. As such, my studies have focused on the mechanism and use of mNPH alone and in conjunction with cisplatinum chemotherapy in murine breast cancer cells and a related in vivo model. MNPH was compared to conventional microwave tumor heating, with results suggesting that mNPH (mNP directly injected into the tumor and immediately activated) and 915 MHz microwave hyperthermia, at the same thermal dose, result in similar tumor regrowth delay kinetics. However, mNPH shows significantly less peri-tumor normal tissue damage. MNPH combined with cisplatinum also demonstrated significant improvements in regrowth delay over either modality applied as a monotherapy. Additional studies demonstrated that a relatively short tumor incubation time prior to AMF exposure (less than 10 minutes) as compared to a 4-hour incubation time, resulted in faster heating rates, but similar regrowth delays when treated to the same thermal dose. The reduction of heating rate correlated well with the observed reduction in mNP concentration in the tumor observed with 4 hour incubation. The ability to effectively deliver cytotoxic mNPs to metastatic tumors is the hope and goal of systemic mNP therapy. However, delivering relevant levels of mNP is proving to be a formidable challenge. To address this issue, I assessed the ability of cisplatinum to simultaneously treat a tumor and improve the uptake of systemically delivered mNPs. Following a cisplatinum pretreatment, systemic mNPs uptake was increased by 3.1 X, in implanted murine breast tumors. Additional in vitro studies showed the necessity of a specific mNP/ Fe architecture and spatial relation for heat-based cytotoxicity in cultured cells.</p>

An in-shoe laser Doppler sensor for assessing plantar blood flow in the diabetic foot. Jonathan Edwin Cobb Plantar ulceration is a complication of the diabetic foot prevalent in adults with type 11 diabetes mellitus. Although neuropathy, microvascular disease and biornechanical factors are all implicated, the mechanism by which the tissue becomes pre-disposed to damage remains unclear. Recent theories suggest that the nutritional supply to the tissue is compromised, either by increased flow through the arteriovenous anastomoses ('capillary steal' theory) or through changes in the micro vascu I ature (haemodynamic hypothesis). Clinical data to support these ideas has been limited to assessment of the unclad foot under rest conditions. A limitation of previous studies has been the exclusion of static and dynamic tissue loading, despite extensive evidence that these biornechanical factors are essential in the development of plantar ulceration. The present study has overcome these problems by allowing assessment of plantar blood flow, in-shoe, during standing and walking. The system comprises a laser Doppler blood flux sensor operating at 780nm, load sensor, measurement shoe, instrumentation, and analysis software. In-vitro calibration was performed using standard techniques. An in-vivo study of a small group of diabetic subjects indicated differences in the blood flux response between diabetic neuropaths, diabetics with vascular complications and a control group. For example, following a loading period of 120s, relative increases in response from rest to peak were: Control (150% to 259%), Vascular (-70% to 242%), Neuropathic (109%-174%) and recovery times to 50% of the peak response were: Control (33s to 45s), Vascular (43s to >120s), Neuropathic (>120s). Dynamic re-perfusion rates (arbitrary units per millisecond) obtained for the swing phase of gait were: Control (6.1 a. u/ms to 7.9 a. u/ms), Vascular (4 a. u/ms to 6.2 a. u/ms), Neuropathic (2.3 a. u/ms to 4.5 a. u/ms).

<p> This dissertation studies hybrid dc-dc power conversion systems based on multiple-input converters (MICs), or more generally, multiport converters. MICs allow for the integration of multiple distributed generation sources and loads. Thanks to the modular design, an MIC yields a scalable system with independent control in all sources. Additional characteristics of MICs include the improved reliability and reduced cost. This dissertation mainly studies three issues of MICs: efficiency improvement, modeling, and control. </p><p> First, this work develops a cost-effective design of a highly-efficient non-isolated MIC without additional components. Time-multiplexing (TM) MICs, which are driven by a time-multiplexing switching control scheme, contain forward-conducting-bidirectionalblocking (FCBB) switches. TM-MICs are considered to be subject to low efficiency because of high power loss introduced by FCBB switches. In order to reduce the power loss in FCBB switches, this work adopts a modified realization of the FCBB switch and proposes a novel switching control strategy. The design and experimental verifications are motivated through a multiple-input (MI) SEPIC converter. Through the design modifications, the switching transients are improved (comparing to the switching transients in a conventional MI-SEPIC) and the power loss is significantly reduced. Moreover, this design maintains a low parts-count because of the absence of additional components. Experimental results show that for output power ranging from 1 W to 220 W, the modified MIC presents high efficiency (96 % optimally). The design can be readily extended to a general n-input SEPIC. The same modifications can be applied to an MI-&Cacute;uk converter. </p><p> Second, this dissertation examines the modeling of TM-MICs. In the dynamic equations of a TM-MIC, a state variable from one input leg is possible to be affected by state variables and switching functions associated with other input legs. In this way, inputs are coupled both topologically and in terms of control actions through switching functions. Coupling among the state variable and the time-multiplexing switching functions complicate TM-MICs&rsquo; behavior. Consequently, substantial modeling errors may occur when a classical averaging approach is used to model an MIC even with moderately high switching frequencies or small ripples. The errors may increase with incremental number of input legs. In addition to demonstrating the special features on MIC modeling, this dissertation uses the generalized averaging approach to generate a more accurate model, which is also used to derive a small-signal model. The proposed model is an important tool that yields better results when analyzing power budgeting, performing large-signal simulations, and designing controllers for TM-MICs via a more precise representation than classical averaging methods. Analyses are supported by simulations and experimental results. </p><p> Third, this dissertation studies application of a decentralized controller on an MISEPIC. For an MIC, a multiple-input-multiple-output (MIMO) state-space representation can be derived by an averaging method. Based on the averaged MIMO model, an MIMO small-signal model can be generated. Both conventional method and modern multivariable frequency analysis are applied to the small-signal model of an MI-SEPIC to evaluate open-loop and closed-loop characteristics. In addition to verifying the nominal stability and nominal performance, this work evaluates robust stability and robust performance with the structured singular value, &mu; . The robust performance test shows that a compromised performance may be expected under the decentralized control. Simulations and experimental results verify the theoretical analysis on stability and demonstrate that the decentralized PI controller could be effective to regulate the output of an MIC under uncertainties. </p><p> Finally, this work studies the control of the MIMO dc-dc converter serving as an active distribution node in an intelligent dc distribution grid. The unified model of a MIMO converter is derived, enabling a systematical analysis and control design that allows this converter to control power flow in all its ports and to act as a power buffer that compensates for mismatches between power generation and consumption. Based on the derived high-order multivariable model, a robust controller is designed with disturbance-attenuation and pole-placement constraints via the linear matrix inequality (LMI) synthesis. The closed-loop robust stability and robust performance are tested through the structured singular value synthesis. Again, the desirable stability and performance are verified by simulations and experimental results.</p>

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-11, Section: B, page: 6956. Adviser: Vijay Singh. Includes bibliographical references (leaves 110-118) Available on microfilm from Pro Quest Information and Learning.

A novel heat pipe (HP) manufacturing method has been developed based on an additive layer manufacturing technique called “selective laser melting” or SLM. This innovation is expected to benefit current applications of aluminium/ammonia heat pipes in space and terrestrial projects as well as many new HP applications. The project was jointly sponsored by the Northumbria University and Thermacore, a world leading heat pipe manufacturing company in the UK, and formed the feasibility stage of a much larger program in Thermacore aiming to develop the next generation of HPs for space applications. In this project, sinter-style aluminium SLM HPs have been produced and tested to prove their functionality and to provide an overall image of the new production process with regard to the major involved parameters. During the project several properties of the new heat pipes e.g. wick porosity, permeability and pore size; wall density, hardness, vibration resistance and optimum SLM build parameters have also been determined by the existing or especially developed rigs in Thermacore or Northumbria University laboratories including scanning electronic microscope (SEM), vibration table, permeability measurement rig, etc. Converting the SLM products into functional heat pipes involves many other steps which have also been completed and explained. At the end of the project two successful functional samples were obtained and clear and precise answers were found to the project questions. SLM process was proved to be capable of producing functional heat pipes. Functional sinter-style heat pipes are proved to be producible by SLM. A numerical design tool is now available to evaluate SLM produced heat pipes and major challenges of this new HP production process including the density of the solid structures and possible contamination of the materials have been identified. Also a reasonably good overall image of this new HP production process and the new HPs has been provided in this project through the conducted measurements and experiments. The contribution of this project to knowledge is supported by two papers published in prestigious heat pipe journals and one paper presented in the 16th international heat pipe conference.

<p> Tracking is a fundamental problem in many computer vision applications. Despite the progress over the last decade, there still exist many challenges especially when the problem is posed in real world scenarios (e.g., cluttered background, occluded objects). Among them drifting has been widely observed to be a problem common to the class of online tracking algorithms - i.e., when challenges such as occlusion or nonlinear deformation of the object occurs, the tracker might lose the target completely in subsequent frames in an image sequence. In this work, we propose to exploit the objectness to partially alleviate the drifting problem with the class of online object tracking and verify the effectiveness of this idea by extensive experimental results. More specifically, a recently developed objectness measure was incorporated into Incremental Learning for Visual Tracking (IVT) algorithm in a principled way. We have come up with a strategy of reinitializing the training samples in the proposed approach to improve the robustness of online tracking. Experimental results show that using objectness measure does help to alleviate its drift to background for certain challenging sequences.</p>

<p> Hemodialysis vascular access, the interface between a dialysis patient and a dialysis machine, is quite literally the lifeblood of a patient's health. Vascular access dysfunction is the leading cause of hospitalization in hemodialysis patients. The occlusive growth of neointimal hyperplasia (NH) in expanded polytetrafluoroethylene (ePTFE) ringed grafts is the primary cause of failure. To further develop a proposed thermal ultrasound treatment to reduce or prevent NH in arteriovenous vascular grafts, the acoustic properties of ePTFE were studied in water and alcohol solutions. Previous reports of ePTFE acoustic properties are critiqued. It was found that the acoustic transmission and attenuation through ePTFE, and therefore the potential for an ultrasound-based therapy for NH, are heavily dependent on the medium in which the graft is immersed, suggesting that the acoustic properties of implanted grafts will change as grafts mature in vivo. The acoustic impedance and attenuation of water-soaked ePTFE were 0.478 &plusmn; 1.43 &times; 10^-2 MRayl and 1.78 &plusmn; 0.111 Np/cm*MHz, respectively, while the acoustic impedance and attenuation of ePTFE in alcohol were 1.49 &plusmn; 0.149 MRayl and 0.77 &plusmn; 1.1 &times; 10^-2 Np/cm*MHz, respectively. The use of focused ultrasound to heat implanted ringed ePTFE grafts was numerically modeled from 1.35- and 1.443-MHz transducers for in vitro geometries. Power deposition and heating, in turn, differed by an order of magnitude between various graft acoustic properties. Graft rings were predicted to be substantial absorbing and scattering features. In vitro phantom models were constructed: one with and one without thermocouples. At 1 W of acoustic power, the maximum temperature rise was 8&ring; C. The thermocouple model containing a water-soaked graft did not experience heating in the far graft wall. The MRTI model confirmed that the graft rings are an absorbing/scattering feature. Heating was not prevented in the presence of water flow through the graft. Water was not heated significantly. Overall, results suggest ultrasound exposure can be used to generate temperature rises corresponding with the potential prevention or inhibition of NH in ringed ePTFE vascular grafts. A hybrid therapeutic/diagnostic transducer design with a therapeutic semi-annular array surrounding a diagnostic linear array is presented. Compared to a solid transducer of the same dimensions, there were only marginal aberrations in the focal plane. Numerical optimization of the element drive configuration indicated that the least distorted focal plane was produced by uniform phase and magnitude at each element.</p>

<p> With the increasing size of wind turbines and the use of flexible and light materials in aerodynamic applications, aeroelastic tailoring for power generation and blade stability has become an important subject in the study of wind turbine dynamics. To this day, coupling of bending and torsion in wind turbine rotor blades has been studied primarily as an elastic mechanism due to a coupling laminate construction. In this report, inertial coupling of bending and torsion, due to offset of axis of elasticity and axis of center of mass, is investigated and numerical simulations are performed to test the validity of the constructed model using an in-house developed aeroelastic numerical tool. A computationally efficient aeroelastic numerical tool, based on Goldstein's helicoidal vortex model with a prescribed wake model and modal coupling of bending and torsion in the blades, is developed for 2-bladed horizontal axis wind turbines and a conceptual study is performed in order to argue the validity of the proposed formulation and numerical construction. The aeroelastic numerical tool, without bending-torsion coupling, was validated (Chattot 2007) using NREL Phase VI wind turbine data, which has become the baseline model in the wind turbine community. Due to novelty of the proposed inertial bending-torsion coupling in the aeroelastic model of the rotor and lack of field data, as well as, other numerical tools available for code to code comparison studies, a thorough numerical investigation of the proposed formulation is performed in order to validate the aeroelastic numerical tool Finally, formulations of geometrically nonlinear beams, elastically nonlinear plates and shells, and a piecewise linear, two degree of freedom, quasi steady, aerodynamic model are presented as an extension for nonlinear wind turbine aeroelastic simulations. Preliminary results of nonlinear beams, plates, shells, and 2 DOF NACA0012 aeroelastic model are presented.</p>