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Publication Development of a Salt Spreader Controller Program using Machine-Sensed Roadway Weather Parameters(2024-05) Avhad, Vaishnavi DattatrayMassachusetts owns over 1,300 material spreaders that deliver salt, sand, and liquid deicers to more than 15,000 lane miles of the Commonwealth’s roadways during winter seasons. In many salt spreader systems, a Remote Weather Information Sensor (RWIS) is used to obtain weather information including temperature, grip level, snow level, wind, etc. In the salt spreader utilized by the Massachusetts Department of Transportation (MassDOT), the application rate of salt is automatically controlled by road grip or manually controlled by a driver or operator, taking into account factors such as weather conditions, road information obtained from RWIS, and visual observations. While controlling the salt rate, along with pavement grip, other road factors like surface temperature, surface state, and visual understanding help the operator decide the salt rate. To make salt spreaders more efficient in deicing material usage, and reduce human effort, it is desirable to eliminate human intervention by avoiding subjective analysis and deciding salt rate based on relevant road parameters. This can be achieved by allowing the system to deliver salt automatically by considering road surface conditions and environmental factors like surface grip, surface temperature, etc. In this thesis, a novel salt spreader control system is outlined, utilizing RWIS input to regulate salt distribution. Through a series of experiments, it was demonstrated that RWIS can be directly used to make intelligent salt-spreading decisions. In some cases, machine learning algorithms can be used to assist in decision-making.Publication Synchronized Object Sharings for Augmented Reality Virtual Conferencing(2024-05) Murray, John O.In the aftermath of recent global events and the gradual subsiding of the pandemic, governments and organizations worldwide are proactively preparing for future challenges. The importance of communication and connection has been underscored in recent years, especially through applications like Skype, Discord, and Zoom, as they play a pivotal role in collaboration and innovation across the world. Virtual platforms have become integral for societies to connect and collaborate, emphasizing the need for the evolution of communication methods to ensure a resilient global future. This thesis examines existing conferencing applications and provides an implementation for a basic Extended Reality (XR) conferencing application. This required implementing an XR-capable application for the HoloLens 2 as well as creating a server application that acts as a hub for all connected users, with a focus on simplicity and modality to allow for future modification and experimentation. Once these applications were created, further tests were performed to evaluate network latency, QR-code scanning metrics, and user quality of experience through a short user study. The subsequent discussion will expound on the implementation process, technical intricacies, and potential issues regarding the integration of XR conferencing systems. As we anticipate the challenges that lie ahead, the development and deployment of a basic conferencing application for the HoloLens 2 signifies a strategic step in building a more connected and resilient future. This thesis will conclude by providing insights into the attained results, offering a comprehensive understanding of the tangible outcomes and implications of this work within the context of advancing communication technologies for a post-pandemic world.Publication Interference Cancellation in Wideband Receivers using Compressed Sensing(2013-02) Peyyeti, Tejaswi CPrevious approach for narrowband interference cancellation based on compressed sensing (CS) in wideband receivers uses orthogonal projections to project away from the interference. This is not effective in the presence of nonlinear LNA (low noise amplifier) and finite bit ADCs (analog-to-digital converters) due to the fact that the nonidealities present will result in irresolvable intermodulation components and corrupt the signal reconstruction. Cancelling out the interferer before reaching the LNA thus becomes very important. A CS measurement matrix with randomly placed zeros in the frequency domain helps in this regard by removing the effect of interference when the signal measurements are performed before the LNA. Using this idea, under much idealized hardware assumptions impressive performance is obtained. The use of binary sequences which makes the hardware implementation simplistic is investigated in this thesis. Searching sequences with many spectral nulls turns out to be nontrivial. A theoretical approach for estimating probability of nulls is provided to reduce significant computational effort in the search and is shown to be close to actual search iterations. The use of real binary sequences (generated using ideal switches) obtained through the search does not do better compared to the orthogonal projection method in the presence of nonlinear LNA.Publication Geometry Optimization of Molecular Systems Using All-Electron Density Functional Theory in a Real-Space Mesh Framework(2013-02) Addagarla, TejasThe goal of computational research in the fields of engineering, physics, chemistry or as a matter of fact in any field, is to study the properties of systems from the various principles available. In computational engineering, particularly in nano-scale simulations involving low-energy physics or chemistry, the goal is to model such structures and understand their properties from first principles or better known as \textit{Ab Initio} calculations. Geometry optimization is the basic component used in modeling molecules. The calculations involved are used to find the coordinates or the positions of the atoms of the molecule where it has the minimum energy and is hence stable. Efficient calculation of the forces acting on the atoms is the most important factor to be able to study the stable geometry of a molecule. In this thesis, the approach used begins with efficient electronic structure calculations using all electron calculations which paves the way for efficient force calculations. Kohn-Sham equations Density functional theory (DFT) are used to find the electron wave functions as accurately as possible using a finite element basis that introduces minimum errors in calculations. FEAST, a highly efficient density matrix based eigenvalue solver, is used to obtain accurate eigenvalues. Derivation of forces is done using the Hellmann-Feynman theorem. To find the minimum energy configuration of the system, Newton's iterative method is used that converges to the desired coordinates where the energy at the global minimum is found. The theory behind energy minimization and the calculations involved will be elaborated in this thesis and a method to move the atom in the existing framework will be discussed.Publication Design of a Tunable Integrated Roofing Filter for Lte Bands(2013-02) Athreyas, NiharThe advent of new standards in wireless communication like the Long Term Evolution (LTE) has resulted in a need for newer and better design of receivers for wireless communication systems, the first step of which is to design a tunable integrated filter on the receiver front end. In this work we propose a new design for a passive tunable integrated Roofing filter for LTE bands. The role of the Roofing filter is to protect the rest of the circuitry from overloading and distortions caused due to large out-of-band signals. This filter protects the rest of the circuitry and hence it gets the name Roofing filter. The Roofing filter is present on the receiver front-end. The filter has a low insertion loss and a high return loss at the input. The bandwidth of the Roofing filter is around 200MHz at the highest values. The filter uses off-chip inductors. The filter has a continuous center frequency tuning range of 2GHz from 0.7GHz to 2.7GHz, which is the allocated frequency range for LTE bands. This continuous tuning is achieved by the use of MOSFET based varactors. The filter is a narrowband filter. The design is implemented in TSMC 65nm CMOS technology.Publication Low Cost Dynamic Architecture Adaptation Schemes for Drowsy Cache Management(2013-02) Prakash, NitinEnergy consumption and speed of execution have long been recognized as conflicting requirements for processor design. In this work, we have developed a low-cost dynamic architecture adaptation scheme to save leakage power in caches. This design uses voltage scaling to implement drowsy caches. The importance of a dynamic scheme for managing drowsy caches, arises from the fact that not only does cache behavior change from one application to the next, but also during different phases of execution within the same application. We discuss various implementations of our scheme that provide a tradeoff between granularity of control and design complexity. We investigate a combination of policies where the cache lines can be turned off completely if they are not accessed, when in the drowsy mode. We also develop a simple dynamic cache-way shutdown mechanism, and propose a combination of our dynamic scheme for drowsy lines, with the cache-way shutdown scheme. Switching off cache ways has the potential of greater energy benefits but provides a very coarse grained control. Combining this with the fine grained scheme of drowsy cache lines allows us to exploit more possibilities for energy benefits without incurring a significant degradation in performance. Keywords: Drowsy Cache, Architecture Adaptation, Low Power, Leakage Reduction, Dynamic SchemePublication Stack Protection Mechanisms In Packet Processing Systems(2013) Wu, PengAs the functionality that current computer network can provide is becoming complicated, a traditional router with application-specific integrated circuit (ASIC) implementation can't satisfy the flexibility requirements. Instead, a programmable packet forward system based on a general-purpose processor could provide the flexibility. While this system provides flexibility, a new potential security issue arises. Usually, software is involved as the packet forward system is programmable. The software's potential vulnerability, especially as to the remote exploits, becomes an issue of network security. In this thesis work, we proposed a software stack overflow vulnerability on click modular router and show how a disastrous denial-of-service attack on click modular router could be triggered by a single packet. In our research work, click modular router runs on Linux operating system based on general-purpose hardware. We actually showed that even a software router run within a modern operating system's protection is vulnerable by elaborate attack. And we checked the possible stack protection mechanisms on modern OS based on general-purpose hardware and proposed a possible stack protection mechanism for embedded OS.Publication Benchmarking Virtual Network Mapping Algorithms(2012-09) Zhu, JinThe network architecture of the current Internet cannot accommodate the deployment of novel network-layer protocols. To address this fundamental problem, network virtualization has been proposed, where a single physical infrastructure is shared among different virtual network slices. A key operational problem in network virtualization is the need to allocate physical node and link resources to virtual network requests. While several different virtual network mapping algorithms have been proposed in literature, it is difficult to compare their performance due to differences in the evaluation methods used. In this thesis work, we proposed VNMBench, a virtual network mapping benchmark that provides a set of standardized inputs and evaluation metrics. Using this benchmark, different algorithms can be evaluated and compared objectively. The benchmark model separate into two parts: static model and dynamic model, which operated in fixed and changed mapping process. We present such an evaluation using three existing virtual network mapping algorithms. We compare the evaluation results of our synthetic benchmark with those of actual Emulab requests to show that VNMBench is sufficiently realistic. We believe this work provides an important foundation to quantitatively evaluating the performance of a critical component in the operation of virtual networks.Publication Large Scale Image Retrieval From Books(2012-09) Zhao, MaoSearch engines play a very important role in daily life. As multimedia product becomes more and more popular, people have developed search engines for images and videos. In the first part of this thesis, I propose a prototype of a book image search engine. I discuss tag representation for the book images, as well as the way to apply the probabilistic model to generate image tags. Then I propose the random walk refinement method using tag similarity graph. The image search system is built on the Galago search engine developed in UMASS CIIR lab. Consider the large amount of data the search engines need to process, I bring in cloud environment for the large-scale distributed computing in the second part of this thesis. I discuss two models, one is the MapReduce model, which is currently one of the most popular technologies in the IT industry, and the other one is the Maiter model. The asynchronous accumulative update mechanism of Maiter model is a great fit for the random walk refinement process, which takes up 84% of the entire run time, and it accelerates the refinement process by 46 times.Publication Terahertz Imaging for Cancer Detection(2012) St. Peter, Benjamin AThis project evaluates the ability of terahertz (THz) radiation to differentiate cancerous from non-cancerous human breast lumpectomy and mastectomy tissue. This is done by aiming a narrow-band THz beam at medical samples and measuring reflected power. THz images of specimens from Breast Conservation Surgery (BCS) were created using a gas laser source and mechanical scanning. The design and characterization of this system is discussed in detail. The images were correlated with optical histological micrographs of the same specimens and discrimination values of more than 70% were found for five of the six samples using Receiver Operating Characteristic (ROC) analysis.Publication Reformulation of the Muffin-Tin Problem in Electronic Structure Calculations within the Feast Framework(2012-09) Levin, Alan RThis thesis describes an accurate and scalable computational method designed to perform nanoelectronic structure calculations. Built around the FEAST framework, this method directly addresses the nonlinear eigenvalue problem. The new approach allows us to bypass traditional approximation techniques typically used for first-principle calculations. As a result, this method is able to take advantage of standard muffin-tin type domain decomposition techniques without being hindered by their perceived limitations. In addition to increased accuracy, this method also has the potential to take advantage of parallel processing for increased scalability. The Introduction presents the motivation behind the proposed method and gives an overview of what will be presented for this thesis. Chapter 1 explains how electronic structure calculations are currently performed, including an overview of Density Functional Theory and the advantages and disadvantages of various numerical techniques. Chapter 2 describes, in detail, the method proposed for this thesis, including mathematical justification, a matrix-level example, and a description of implementing the FEAST algorithm. Chapter 3 presents and discusses results from numerical experiments for Hydrogen and various Hydrogen molecules, Methane, Ethane, and Benzene. Chapter 4 concludes with a summary of the presented work and its impact in the field.Publication Development of a Solid-State Doppler Marine Radar(2008) Pathak, Gita PPublication A Theoretical Approach to Fault Analysis and Mitigation in Nanoscale Fabrics(2012-09) Khan, Md Muwyid UzzamanHigh defect rates are associated with novel nanodevice-based systems owing to unconventional and self-assembly based manufacturing processes. Furthermore, in emerging nanosystems, fault mechanisms and distributions may be very different from CMOS due to unique physical layer aspects, and emerging circuit and logic styles. Thus, theoretical fault models for nanosystems are necessary to extract detailed characteristics of fault generation and propagation. Using the intuition garnered from the theoretical analysis, modular and structural redundancy schemes can be specifically tailored to the intricacies of the fabric in order to achieve higher reliability of output signals. In this thesis, we develop a detailed analytical fault model for the Nanoscale Application Specific Integrated Circuits (NASIC) fabric that can determine probabilities of output faults taking into account the defect scenarios, the logic and circuit style of the fabric as well as structural redundancy schemes that may be incorporated in the circuits. Evaluation of fault rates using the analytical model for single NASIC tiles show an inequality of the probability of output faulty ‘1’s and ‘0’s. To mitigate the effects of the unequal fault rates, biased voting schemes are introduced and are shown to achieve up to 27% improvement in the reliability of output signals compared to conventional majority voting schemes. NASIC circuits have to be cascaded in order to build larger systems. Furthermore, modular redundancy alone will be insufficient to tolerate high defect rates since multiple input modules may be faulty. Hence incorporation of structural redundancy is crucial. Thus in this thesis, we study the propagation of faults through a cascade of NASIC circuits employing the conventional structural redundancy scheme which is referred to here as the Regular Structural Redundancy. In our analysis we find that although circuits with Regular Structural Redundancy achieve greater signal reliability compared to non-redundant circuits, the signal reliability rapidly drops along the cascade due to an escalation of faulty ‘0’s. This effect is attributed to the poor tolerance of input faulty ‘0’s exhibited by circuits with the Regular Structural Redundancy. Having identified this, we design a new scheme called the Staggered Structural Redundancy prioritizing the tolerance of input faulty ‘0’s. A cascade of circuits employing the Staggered Structural Redundancy is shown to maintain signal reliability greater than 0.98 for over 100 levels of cascade at 5% defect rate whereas the signal reliability for a cascade of circuits with the Regular Structural Redundancy dropped to 0.5 after 7 levels of cascade.Publication Heterogeneous Graphene Nanoribbon-CMOS Multi-State Volatile Random Access Memory Fabric(2012) Khasanvis, SantoshCMOS SRAM area scaling is slowing down due to several challenges faced by transistors at nanoscale such as increased leakage. This calls for new concepts and technologies to overcome CMOS scaling limitations. In this thesis, we propose a multi-state memory to store multiple bits in a single cell, enabled by graphene and graphene nanoribbon crossbar devices (xGNR). This could provide a new dimension for scaling. We present a new multi-state volatile memory fabric called Graphene Nanoribbon Tunneling Random Access Memory (GNTRAM) featuring a heterogeneous integration between graphene and CMOS. A latch based on the xGNR devices is used as the memory element which exhibits 3 stable states. We propose binary and ternary GNTRAM and compare them with respect to 16nm CMOS SRAM and 3T DRAM. Ternary GNTRAM (1.58 bits/cell) shows up to 1.77x density-per-bit benefit over CMOS SRAMs and 1.42x benefit over 3T DRAM in 16nm technology node. Ternary GNTRAM is also up to 1196x more power-efficient per bit against high-performance CMOS SRAMs during stand-by. To enable further scaling, we explore two approaches to increase the number of bits per cell. We propose quaternary GNTRAM (2 bits/cell) using these approaches and extensively benchmark these designs. The first uses additional xGNR devices in the latch to achieve 4 stable states and the quaternary memory shows up to 2.27x density benefit vs. 16nm CMOS SRAMs and 1.8x vs. 3T DRAM. It has comparable read performance in addition to being power-efficient, up to 1.32x during active period and 818x during stand-by against high performance SRAMs. However, the need for relatively high-voltage operation may ultimately limit this scaling approach. An alternative approach is also explored by increasing the stub length in the xGNR devices, which allows for storing 2 bits per cell without requiring an increased operating voltage. This approach for quaternary GNTRAM shows higher benefits in terms of power, specifically up to 4.67x in terms of active power and 3498x during stand-by against high-performance SRAMs. Multi-bit GNTRAM has the potential to realize high-density low-power nanoscale memories. Further improvements may be possible by using graphene more extensively, as graphene transistors become available in future.Publication Energy Efficient Adaptive Reed-Solomon Decoding System(2008) Allen, Jonathan DThis work presents an energy efficient adaptive error correction system utilizing the Reed-Solomon errors-and-erasures algorithm, targeted to an Altera Stratix FPGA device. The system adapts to changing channel conditions by reconfiguring the system with different decoders to allow for the lowest possible energy consumption rate that the current channel conditions will allow. A series of energy saving optimizations were applied to a set of previous designs, resulting in a reduction in the energy required to decode a megabit of data of more than 70%. In addition, a new channel model was used to assess the effects of differing reconfiguration rates on codeword error rate, energy consumption, and decoding speed.Publication Techniques for Detection of Malicious Packet Drops in Networks(2012) Desai, Vikram RThe introduction of programmability and dynamic protocol deployment in routers, there would be an increase in the potential vulnerabilities and attacks . The next- generation Internet promises to provide a fundamental shift in the underlying architecture to support dynamic deployment of network protocols. In this thesis, we consider the problem of detecting malicious packet drops in routers. Specifically, we focus on an attack scenario, where a router selectively drops packets destined for another node. Detecting such an attack is challenging since it requires differentiating malicious packet drops from congestion-based packet losses. We propose a controller- based malicious packet detection technique that effectively detects malicious routers using delayed sampling technique and verification of the evidence. The verification involves periodically determining congestion losses in the network and comparing the forwarding behaviors of the adjoining routers to affirm the state of a router in the network. We provide a performance analysis of the detection accuracy and quantify the communication overhead of our system. Our results show that our technique provides accurate detection with low performance overhead.Publication The Radiation Quality Factor Of Vertically Polarized Spherical Antennas Above A Conducting Ground Plane(2012-09) Chang, Hsieh-chiThe radiation quality factor of small vertically polarized antennas above a ground plane is investigated. Although the quality factor of small antennas in free space has been investigated extensively in the past, the exact effect of a conducting ground plane on the antenna bandwidth is not clearly understood. In this thesis, quality factors of vertically polarized antennas above a ground plane are computed and compared with their free-space counterparts. The theoretical results on quality factors are validated with simulations of electrically small spherical helix antennas.Publication Towards Logic Functions as the Device using Spin Wave Functions Nanofabric(2012-05) Shabadi, PrasadAs CMOS technology scaling is fast approaching its fundamental limits, several new nano-electronic devices have been proposed as possible alternatives to MOSFETs. Research on emerging devices mainly focusses on improving the intrinsic characteristics of these single devices keeping the overall integration approach fairly conventional. However, due to high logic complexity and wiring requirements, the overall system-level power, performance and area do not scale proportional to that of individual devices. Thereby, we propose a fundamental shift in mindset, to make the devices themselves more functional than simple switches. Our goal in this thesis is to develop a new nanoscale fabric paradigm that enables realization of arbitrary logic functions (with high fan-in/fan-out) more efficiently. We leverage on non-equilibrium spin wave physical phenomenon and wave interference to realize these elementary functions called Spin Wave Functions (SPWFs). In the proposed fabric, computation is based on the principle of wave superposition. Information is encoded both in the phase and amplitude of spin waves; thereby providing an opportunity for compressed data representation. Moreover, spin wave propagation does not involve any physical movement of charge particles. This provides a fundamental advantage over conventional charge based electronics and opens new horizons for novel nano-scale architectures. We show several variants of the SPWFs based on topology, signal weights, control inputs and wave frequencies. SPWF based designs of arithmetic circuits like adders and parallel counters are presented. Our efforts towards developing new architectures using SPWFs places strong emphasis on integrated fabric-circuit exploration methodology. With different topologies and circuit styles we have explored how capabilities at individual fabric components level can affect design and vice versa. Our estimates on benefits vs. 45nm CMOS implementation show that, for a 1-bit adder, up to 40x reduction in area and 228x reduction in power is possible. For the 2-bit adder, results show that up to 33x area reduction and 222x reduction in power may be possible. Building large scale SPWF-based systems, requires mechanisms for synchronization and data streaming. In this thesis, we present data streaming approaches based on Asynchronous SPWFs (A-SPWFs). As an example, a 32-bit Carry Completion Sensing Adder (CCSA) is shown based on the A-SPWF approach with preliminary power, performance and area evaluations.Publication Global Interconnects in the Presence of Uncertainty(2008) Benito, Ibis DGlobal interconnect reliability is becoming a bigger issue as we scale down further into the submicron regime. As transistor dimensions get smaller, variations in the manufacturing process, and temperature variations may cause undesired behavior, and as a result, compromise performance. This work makes an effort to characterize the effects of such variations, to provide designers with a guideline for making designs tolerant to these variations while benefiting from tighter design margins. Since interconnects contribute to most of the delay and power on a chip, interconnect performance becomes a primary issue in design. One of the main concerns when considering physical transistor dimension variations is the effect on delay. Due to smaller transistor dimensions, the photolithographic process may produce transistors with significant variations from the ideal physical dimensions. Such variations cause delay uncertainty which can lead to over or underestimation in the design phase. This work examines interconnects to establish a guideline of the effect that process variations have on delay. A repeated interconnect is analyzed and the effects of physical device variations on delay are observed. Given the delay distribution in the presence of Leff variation, a supply voltage assignment technique is proposed to correct the observed deviation from the nominal delay on a long, repeated interconnect. This technique results in a significant reduction of the delay distribution, with a negligible power overhead. After looking at static variation effects on interconnect performance, this thesis addresses thermal variations on global signals, which cause delay degradation and may lead to timing failures. Given the presence of a large thermal gradient along a clock signal in a data path clocked by two leaves of an H-tree, several thermal scenarios which can compromise timing are discussed. A buffer-based skew compensation technique is proposed to correct the effect of thermal and manufacturing variations on this system. Having characterized repeated interconnect performance under process variations, the bandwidth of the line can be more effectively utilized by using a technique called phase coding. Phase coded interconnects are introduced in the context of using them once an interconnect has been adequately modeled in the presence of variations. With guidelines quantifying the effects of process variations on interconnect techniques and careful characterization, designers can factor these considerations into their design process, reducing the variation from the nominal expected behavior and allowing for smaller design margins. This will lead to more reliable products as we advance into future technologies and transistor dimensions get smaller.Publication The Measurement of Internal Temperature Anomalies in the Body Using Microwave Radiometry and Anatomical Information: Inference Methods and Error Models(2012) Sobers, Tamara VThe ability to observe temperature variations inside the human body may help in detecting the presence of medical anomalies. Abnormal changes in physiological parameters (such as metabolic and blood perfusion rates) cause localized tissue temperature change. If the anatomical information of an observed tissue region is known, then a nominal temperature profile can be created using the nominal physiological parameters. Temperature-varying radiation emitted from the human body can be captured using microwave radiometry and compared to the expected radiation from nominal temperature profiles to detect anomalies. Microwave radiometry is a passive system with the ability to capture radiation from tissue up to several centimeters deep into the body. Our proposed method is to use microwave radiometry in conjunction with another imaging modality (such as ultrasound) that can provide the anatomical information needed to generate nominal profiles and improve detection of temperature anomalies. An inference framework is developed for using the nominal temperature profiles and radiometric weighting functions obtained from electromagnetic simulation software, to detect and estimate the location of temperature anomalies. The effects on inference performance of random and systematic deviations from nominal tissue parameter values in normal tissue are discussed and analyzed.