As one of the major computational electromagnetic modeling methods, finite-difference time-domain (FDTD) technique tackles problems by providing a full wave solution.... ]]> Zhengwei Hao http://iris.lib.neu.edu/elec_eng_diss/71 http://iris.lib.neu.edu/elec_eng_diss/71 Mon, 20 May 2013 08:44:48 PDT For 20 years, single walled carbon nanotubes (SWNTs) have been studied actively due to their unique one-dimensional nanostructure and superior electrical, thermal, and mechanical properties. For these reasons, they offer the potential to serve as building blocks for future electronic devices such as field effect transistors (FETs), electromechanical devices, and various sensors. In order to realize these applications, it is crucial to develop a simple, scalable, and reliable nanomanufacturing process that controllably places aligned SWNTs in desired locations, orientations, and dimensions. Also electronic properties (semiconducting/metallic) of SWNTs and their organized networks must be controlled for the desired performance of devices... ]]> Young Lae Kim http://iris.lib.neu.edu/elec_eng_diss/70 http://iris.lib.neu.edu/elec_eng_diss/70 Thu, 16 May 2013 11:40:39 PDT High sensitivity and high specificity detection of disease biomarkers is crucial for early diagnostics and monitoring of diseases. Current cancer diagnostics tools are invasive and uncomfortable. Blood tests that are currently being used also lack sufficient sensitivity and specificity for early detection of diseases. In this thesis, a design for highly sensitive micron scale in-vivo sensor platform device for simultaneous detection of multiple disease biomarkers is presented. The biosensor microchip is 0.25mm in diameter, based on SU-8 polymeric platform fabricated incorporating four active isolated areas as small as 70µm x 70µm. Conventional micro and nanofabrication processes were used for fabrication... ]]> Asanterabi Malima http://iris.lib.neu.edu/elec_eng_diss/69 http://iris.lib.neu.edu/elec_eng_diss/69 Wed, 15 May 2013 12:06:08 PDT Collagen is one of the most abundant proteins found in the human body. Its crystalline structure possesses no centrosymmetry, allowing it to emit second-harmonic waves. Second harmonic generation (SHG) microscopy utilizes the latter quality to produce high-resolution images of collagen rich tissues and therefore become a key research tool in the biomedical field. We developed a new model, intended to be used together with second harmonic generation (SHG) microscopy, to thoroughly investigate collagen-based tissues. We use our SHG model to reveal information in real time from enzymatic biochemical processes. We also present a novel method used to measure quantitatively the... ]]> Yair Mega http://iris.lib.neu.edu/elec_eng_diss/68 http://iris.lib.neu.edu/elec_eng_diss/68 Wed, 08 May 2013 12:51:50 PDT Various sensor systems are widely used in inspecting the nation's civil infrastructure of roads and bridges. Unfortunately, infrastructure integrity cannot be conveniently evaluated in an economically or a time efficient way using these existing systems. This dissertation presents a non-destructive and non-contact acoustic sensing approach for fast inspection of road and bridge deck conditions with vehicles running at normal speed without stopping traffic. This approach, which uses an instantaneous and real-time dynamic tire pressure sensor (DTPS), possesses the capability to inspect pavement conditions from a moving vehicle. In this dissertation, verifications of the DTPS concept of sensing pressure inside the... ]]> Qi Wang http://iris.lib.neu.edu/elec_eng_diss/67 http://iris.lib.neu.edu/elec_eng_diss/67 Mon, 11 Mar 2013 12:41:09 PDT Modern ultra wideband communication systems and radars, and metrology systems all need reconfigurable subsystems that are compact, lightweight, and power efficient. At the same time, isolators with a large bandwidth are widely used in communication systems for enhancing the isolation between the sensitive receiver and power transmitter. Conventional Isolators based on the non-reciprocal ferromagnetic resonance (FMR) of microwave ferrites in waveguide. However, these approaches are usually bulky. This dissertation focuses on theoretical study, numerical evaluation and measurement verification of novel planar RF/microwave devices with magnetic substrates and superstrates, demonstrating tunable and non-reciprocal characteristics, so that size, weight and cost of... ]]> Jing Wu http://iris.lib.neu.edu/elec_eng_diss/66 http://iris.lib.neu.edu/elec_eng_diss/66 Mon, 04 Mar 2013 09:25:53 PST This thesis initially presents the problem of stability pertaining to delay systems and provides useful results on stability analysis using linear matrix inequalities (LMIs). The connection between recently published results on stability robustness in the domain of time delays and robust stability with respect to structured perturbation of system matrices is investigated. Consequently, computable stability radius formulas for multi-delay systems using Rekasius substitution are derived. Using the concepts of kernel and offspring curves, which describe the complete portrait of possible imaginary characteristic roots of the nominal system, the fundamental stability region is defined among a set of disjoint stability regions... ]]> Hanai Abd El-Moneim Sadaka http://iris.lib.neu.edu/elec_eng_diss/65 http://iris.lib.neu.edu/elec_eng_diss/65 Fri, 01 Mar 2013 09:38:28 PST Radio frequency (RF) wireless energy transfer and energy harvesting from external sources promise a battery-free paradigm for resource constrained wireless sensor networks (WSNs). The objective of this thesis is to advance the engineering of these energy harvesting components interfaced with off-the-shelf motes and formulate the design of higher layer link and routing protocols for a WSN composed of such motes. The specific contributions of the thesis include: (i) optimization and implementation of RF energy harvesting circuits, (ii) medium access control protocol for scenarios with multiple energy transmitters, (iii) cross-layer protocol design that includes joint duty cycle determination and routing, and... ]]> Prusayon Nintanavongsa http://iris.lib.neu.edu/elec_eng_diss/64 http://iris.lib.neu.edu/elec_eng_diss/64 Thu, 28 Feb 2013 12:08:00 PST Graphics processing units (GPUs) offer significant speedups over CPUs for certain classes of applications. However, maximizing GPU performance can be a difficult task due to the relatively high programming complexity as well as frequent hardware changes. Important performance optimizations are applied by the GPU compiler ahead of time and require fixed parameter values at compile time. As a result, many GPU codes offer minimum levels of adaptability to variations among problem instances and hardware configurations. These factors limit code reuse and the applicability of GPU computing to a wider variety of problems. This dissertation introduces GPGPU kernel specialization, a technique... ]]> Nicholas Moore http://iris.lib.neu.edu/elec_eng_diss/63 http://iris.lib.neu.edu/elec_eng_diss/63 Wed, 27 Feb 2013 13:33:03 PST Cardiac arrest caused by the rupture of atherosclerotic plaques is one of the main causes of death in the western world. Intravascular near-infrared fluorescence (iNIRF) imaging can be used to detect plaques at high risk of rupture, utilizing a catheter that delivers laser light to excite fluorochromes specific to molecules produced by inflammation and other biological processes associated with plaque formation. One significant feature of iNIRF imaging is its capability to image through blood. However, because of the absorption and scattering of photons caused by red blood cells, fluorescence intensity detected through blood is dependent on the distance between the... ]]> Georgios Mallas http://iris.lib.neu.edu/elec_eng_diss/62 http://iris.lib.neu.edu/elec_eng_diss/62 Tue, 26 Feb 2013 10:34:30 PST Software Defined Radio (SDR) is a radio in which all or majority of the functionality of the physical layer is implemented in software. One of the biggest benefits of SDR is the relative ease in which the functionality can be changed. Such flexibility could potentially be used in achieving interoperability of the communications systems. Cognitive Radio (CR)—a paradigm that combines SDR technology with a cognitive agent—allows radios to change their operational behaviors in order to achieve a variety of goals, e.g. performance optimization, power saving, opportunistic use of resources, etc. Cognitive Radios are expected to play the leading role in... ]]> Janusz Leszek Lechowicz http://iris.lib.neu.edu/elec_eng_diss/61 http://iris.lib.neu.edu/elec_eng_diss/61 Wed, 20 Feb 2013 12:42:03 PST To prolong the life of the battery, the analog and digital modules in modern mixed-signal SoCs are designed to consume extremely low power (

In this dissertation, a new 4-to-3 step-down topology for on-chip SC DC-DC converters, which efficiency is less sensitive to increasing bottom-plate capacitance ratio (α) than the conventional topologies, is proposed. In addition, two different implementations of on-chip SC DC-DC converters using the new 4-to-3 step-down topology are presented.

For the first implementation, the on-chip SC DC-DC converter supports a programmable regulated load voltage ranging from 2.6V to 3.2V out of 5V input power supply. Only MOS... ]]> Heungjun Jeon http://iris.lib.neu.edu/elec_eng_diss/60 http://iris.lib.neu.edu/elec_eng_diss/60 Fri, 15 Feb 2013 10:03:04 PST Ultraspectral images capture 2D data tuned at different wavelengths across the mid infrared electromagnetic spectrum. Atmospheric Infrared Sounder (AIRS) remote sensors are ultraspectral sensors that generate images with thousands of highly correlated bands and are considered the future of spectroscopy. The major application of AIRS is the acquisition of atmospheric parameters such as gases, temperature and other quantities to perform climate and weather forecast. Because typical AIRS images are well over 40 MB in size and because they are captured in remote locations data compression (before transmission) becomes a very critical issue. Existent compression studies of AIRS data adapt generic... ]]> Rolando Herrero http://iris.lib.neu.edu/elec_eng_diss/59 http://iris.lib.neu.edu/elec_eng_diss/59 Fri, 15 Feb 2013 09:25:14 PST We provide a formulation and adaptive solution for power flow optimization in polyphase power systems with significant source (line) impedance in the presence of either linear or nonlinear loads. The known optimal solution for this problem relies on (typically time-variant) network and load parameters that are not easy to determine during operation. We developed an adaptive compensation scheme that relies only on measurements of the load voltage and current so as to allow precise control of the power delivered to the compensated load as well as of the power flow out of the compensator, while reducing the power loss in... ]]> Ronald Didier Hernández http://iris.lib.neu.edu/elec_eng_diss/58 http://iris.lib.neu.edu/elec_eng_diss/58 Fri, 15 Feb 2013 08:59:42 PST In this dissertation, computational methods are developed for modeling and reconstruction of ultrasound tomographic imaging. A fast method for computing the acoustic field of ultrasound transducers is presented with application to rectangular elements that are cylindrically focused. Our motivation is the rapid calculation of imaging kernels for physics based diagnostic imaging where current methods are computationally too intensive. Here the surface integral defining the acoustic field from a baffled piston is converted to a three-dimensional spatial convolution of the element surface and the Green's function. A three-dimensional version of the overlap-save method from digital signal processing is employed to obtain... ]]> Hüseyin Emre Güven http://iris.lib.neu.edu/elec_eng_diss/57 http://iris.lib.neu.edu/elec_eng_diss/57 Thu, 14 Feb 2013 12:23:19 PST From ecology and evolutionary biology to social sciences, and from systems and control theory to aerospace and wireless sensor networks, researchers have been trying to develop an understanding of how a group of moving objects such as flocks of birds, schools of fish and crowds of people can perform collective tasks such as reaching a consensus or moving in a formation without centralized coordination. Researchers in the fields of robotics and control theory have also become interested in cooperative control of multi-agent systems such as a group of unmanned vehicles due to its vast variety of applications. This dissertation focuses... ]]> Rasoul Ghadami http://iris.lib.neu.edu/elec_eng_diss/56 http://iris.lib.neu.edu/elec_eng_diss/56 Mon, 11 Feb 2013 07:48:53 PST Ferrite materials are widely used in passive and tunable electromagnetic signal processing devices such as phase shifters, circulators, isolators, and filters. These materials can also be used as tunable antenna substrates and EMI suppression cores. Due to their excellent dielectric properties, ferrites possess the advantages of low loss and high power handling relative to semiconductors. Typically, parameters of magnetic materials are controlled by an external magnetic field thus allowing for tuning of device performance. Magnetic fields are usually generated using permanent magnets or current driven coils, leading to relatively large component size, weight, and cost, as well as slow response... ]]> Khabat Ebnabbasi http://iris.lib.neu.edu/elec_eng_diss/55 http://iris.lib.neu.edu/elec_eng_diss/55 Fri, 01 Feb 2013 09:05:38 PST The Carbon NanoTube Field Effect Transistor (CNTFET) is one of the most promising emerging technologies to extend and complement silicon MOSFET; this is due to its excellent performance characteristics and similarity in operational principles and device structure. During manufacturing, CNTs are usually grown or transferred to a substrate with a fixed pitch prior to defining the gates and the contacts. One of the likely defects occurs during the deposition of the CNTs, i.e. only some of the required CNTs are deposited. These defects significantly affect the performance of the CNTFET, because the number of CNTs present in the channel is... ]]> Geunho Cho http://iris.lib.neu.edu/elec_eng_diss/54 http://iris.lib.neu.edu/elec_eng_diss/54 Fri, 25 Jan 2013 10:30:46 PST Homogeneous multicore processors, heterogeneous multicore processors, high performance accelerators, and other heterogeneous architectures have significant computing potential over traditional single core processors. Computer systems comprised of these specialized processing elements are increasingly common. Due to the increased complexity of these architectures, programming them has become increasingly complex and error prone. Each of these architectures have different memory systems, programming languages and development environments. This has driven the need for portable programming APIs and tools that allow developers to easily exploit all of the computational power of these platforms and effortlessly move their programs between different computing systems. To deal with... ]]> James Brock