69 results
Search Results
Now showing 1 - 10 of 69
Item Turning Visual Noise Into Hardware Efficiency: Systems of Viewer and Content Aware Power-Quality Scalable Embedded Memories With ECC-Adaptation for Big Videos and Deep Learning(North Dakota State University, 2021) Haidous, Ali AhmadMobile devices, such as smart phones, are being increasingly utilized for watching videos. Video processing requires frequent memory access that consume a significant amount of power due to large data size and intensive computational requirements. This limits battery life and frustrates users. Memory designers are focused on hardware-level power-optimization techniques without consideration of how hardware performance influences viewers' actual experience. The human visual system is limited in its ability to detect subtle degradations in image quality. For example, under conditions of high ambient illumination – such as outdoors in direct sunlight – the veiling luminance (i.e., glare) on the screen of a mobile device can effectively mask imperfections in the image. Under these circumstances, a video can be rendered in lower than full quality without the viewer being able to detect any difference in quality. As a result, the isolation between hardware design and viewer experience significantly increases hardware implementation overhead and power consumption due to overly pessimistic design margins, while integrating the two would have the opposite effect. In this dissertation, viewer-awareness, content-awareness, and hardware adaptation are integrated to achieve power optimization without degrading video quality, as perceived by users. Specifically, this dissertation will (i) experimentally and mathematically connect viewer experience, ambient illuminance, and memory performance; (ii) develop energy-quality adaptive hardware that can adjust memory usage based on ambient luminance to reduce power usage without impacting viewer experience; (iii) design various mobile video systems to fully evaluate the effectiveness of the developed methodologies; and (iv) provide an overview of bleeding edge related area research then push the boundary further using the novel techniques discussed to achieve optimized quality, silicone area overhead, and power reduction in video memory.Item High-Power, High-Efficiency, Multi-Functional CMOS Radio Frequency Integrated Circuit for Wireless Communication of Unmanned Aircraft System(North Dakota State University, 2017) Roy, PalashRecently the Unmanned Aircraft System (UAS) has become very popular due to its current and projected opportunities in diversified applications from surveillance to security to militry. The Federal Aviation Administration (FAA) has mandated for all UASs to be equipped with an Automatic Dependent Surveillance Broadcast (ADS-B) transmitter by 2020. ADS-B is a next generation aircraft communication system, operating with two frequencies, 978 MHZ and 1090 MHz, which will transmit the information of identification, and precise position of an airplane to the nearby airplanes and ground station. At present, the ADS-B transmitter is fabricated with hybrid integrated circuits (HICs) in three different modules: a Phase Locked Loop (PLL) module, an Up-converter (modulator) module and a Power Amplifier (PA) module [8-10] which makes the system very large in size and expensive. In this work, for the first time an ADS-B transmitter as a part of Universal Access Transceievr (UAT) and Universal Beacon Radio (UBR) has beeen developed in a fully integrated single chip using the Complementary Metal Oxide Semiconductor (CMOS) process which is capable of operating both at 978 MHz UAT and 1090 MHz Extended Squitter (ES) modes. The chip provides the modulated output power of 23 dBm which is sufficient for the UAS to operate below class-A airspace. If the UAS needs to operate above this range or needs to operate for a manned aircraft system, this single chip ADS-B transmitter can be interfaced to drive an off-chip high-power PA, and, thus, it will reduce the burden of the input power and the gain of the off-chip PA. The chip supports both single tone and modulated baseband signals. In addition, this chip is capable of operating a part of new datalinks (960 MHz to 1164 MHz) and DME bands for UAS.Item Metamaterial-Inspired Reconfigurable Series-Fed Arrays(North Dakota State University, 2014) Ijaz, BilalOne of the biggest challenges in modern day wireless communication systems is to attain agility and provide more degrees of freedom in parameters such as frequency, radiation pattern and polarization. Existing phased array antenna technology has limitations in frequency bandwidth and scan angle. So it is important to design frequency reconfigurable antenna arrays which can provide two different frequency bandwidths with a broadside radiation pattern having a lower sidelobe and reduced frequency scanning. The reconfigurable antenna array inspired by the properties of metamaterials presented here provides a solution to attain frequency agility in a wireless communication system. The adaptive change in operating frequency is attained by using RF p-i-n diodes on the antenna array. The artificially made materials having properties of negative permeability and negative permittivity have antiparallel group and phase velocities, and, in consequence of that, they support backward wave propagation. The key idea of this work is to demonstrate that the properties of metamaterial non-radiating phase shifting transmission lines can be utilized to design a series-fed antenna array to operate at two different frequency bands with a broadside radiation pattern in both configurations. In this research, first, a design of a series-fed microstrip array with composite right/left-handed transmission lines (CRLH-TLs) is proposed. To ensure that each element in the array is driven with the same voltage phase, dual-band CRLH-TLs are adopted instead of meander-line microstrip lines to provide a compact interconnect with a zero phase-constant at the frequency of operation. Next, the work is extended to design a reconfigurable series-fed antenna array with reconfigurable metamaterial interconnects, and the expressions for array factor are derived for both switching bands.Item Utilizing Recommender Systems as an Analysis Tool for Measuring Network Dynamics(North Dakota State University, 2015) Usman Shahid Khan, MuhammadRecommender systems apply numerous knowledge discovery techniques to suggest the preferred products, information, or service on contextual data. In our study, we utilize the recommender system for analyzing and measuring the network dynamics. The dynamic factors such as change in network shape or data size affect the performance of the networks and make it harder for the optimization techniques to be used for finding the optimum solution. In our research, we focused on the monitoring and analyzing the dynamic factors involved in two networks: (a) body area networks and (b) road networks; and based on the study proposed the efficient solution for mitigating the negative effects of the dynamic factors involved using recommender systems. In body area networks, we monitored the dynamically changing body area sensors data and studied the correlation between the sensors’ location and activity recognition. We proposed a cloud based framework that has employed a feature descriptor called Local Energy-based Shape Histogram (LESH) to preserve the maximum information of local energy. We have also used the Wearable Action Recognition Database (WARD) dataset to perform the experiments. Based on our study we proposed the best combination of sensors for various activities recognition. In road networks, we monitored the congestion during large-scale emergency evacuation and proposed efficient route recommendation service that helps in fast and safe evacuation. To respond to emergencies in a fast and an effective manner, it is of critical importance to have efficient evacuation plans that lead to minimum road congestion. The existing approaches, mostly based on multi-objective optimizations, are not scalable enough when involve numerous time varying parameters, such as traffic volume, safety status, and weather conditions. In this study, we propose a new scalable emergency evacuation service that recommends the evacuees with the most preferred routes towards safe locations during a disaster. The evacuees are directed towards those routes that are safe and have least congestion resulting in decreased evacuation time. The results indicated the improved efficiency of our service for average evacuation times and evacuation delays.Item Timed Refinement for Verification of Real-Time Object Code Programs(North Dakota State University, 2018) Dubasi, Mohana Asha LathaReal-time systems such as medical devices, surgical robots, and microprocessors are safety-critical applications that have hard timing constraint. The correctness of real-time systems is important as the failure may result in severe consequences such as loss of money, time and human life. These real-time systems have software to control their behavior. Typically, this software has source code which is converted to object code and then executed in safety-critical embedded devices. Therefore, it is important to ensure that both source code and object code are error-free. When dealing with safety-critical systems, formal verification techniques have laid the foundation for ensuring software correctness. Refinement based technique in formal verification can be used for the verification of real-time interrupt-driven object code. This dissertation presents an automated tool that verifies the functional and timing correctness of real-time interrupt-driven object code programs. The tool has been developed in three stages. In the first stage, a novel timed refinement procedure that checks for timing properties has been developed and applied on six case studies. The required model and an abstraction technique were generated manually. The results indicate that the proposed abstraction technique reduces the size of the implementation model by at least four orders of magnitude. In the second stage, the proposed abstraction technique has been automated. This technique has been applied to thirty different case studies. The results indicate that the automated abstraction technique can easily reduce the model size, which would in turn significantly reduce the verification time. In the final stage, two new automated algorithms are proposed which would check the functional properties through safety and liveness. These algorithms were applied to the same thirty case studies. The results indicate that the functional verification can be performed in less than a second for the reduced model. The benefits of automating the verification process for real-time interrupt-driven object code include: 1) the overall size of the implementation model has reduced significantly; 2) the verification is within a reasonable time; 3) can be applied multiple times in the system development process.Item Formal Verification Techniques for Safety Critical Medical Device Software Control(North Dakota State University, 2016) Shuja, SanaSafety-critical medical devices play an important role in improving patients health and lifestyle. Faulty behaviors of such devices can cause harm or even death. Often these faulty behaviors are caused due to bugs in software programs used for digital control of the device. We present a formal veri cation methodology that can be used to check the correctness of object code programs that implement the safety-critical control functions of these medical devices. Our methodology is based on the theory of Well-Founded Equivalence Bisimulation (WEB) re nement, where both formal speci cations and implementations are treated as transition systems. First, we present formal speci cation model for the medical device. Second, we develop correctness proof obligations that can be applied to validate object code programs used in these devices. Formal methods are not widely employed for the veri cation of safety critical medical devices. However, using our methodology we were able to bridge the gap between two very important phases of software life cycle: speci cation and veri cation.Item Design and Analysis of New Printed Wideband Antennas for Wireless Applications(North Dakota State University, 2014) Asirvatham, KobyIn this study a simple method to develop a wideband antenna is proposed. With this new technique a dipole antenna with a 48% frequency bandwidth is transformed to achieve a 120% frequency bandwidth for a voltage standing-wave ratio ≤ 2. Two different designs are tested and their performance is compared: the segmented-ring antenna and the split-ring antenna. Both antennas achieved a stable radiation pattern and a moderate gain. Nearly omnidirectional radiation patterns have been observed in both the XZ and YZ-planes. Finally, simple passive arrays are presented, demonstrating the usefulness of the split-ring antenna as an array element. Beam steering is demonstrated with a four element passive array using horizontal meandering lines. This novel antenna has wide applications in high-capacity wireless communication system.Item Perceptual Video Quality Model and its Application in Wireless Multimedia Communications(North Dakota State University, 2015) Hameed, AbdulWith the exponential growth of video traffic over wireless networked and embedded devices such as mobile phones and sensors, mechanisms are needed to predict the perceptual quality of video in real time and with low complexity, based on which networking protocols can control video quality and optimize network resources to meet the quality of experience requirements of users. This thesis is composed of three related pieces of work. In the first piece of work, an efficient and light-weight video quality prediction model through partial parsing of compressed from the H.264/AVC compressed bitstream is proposed. A set of features were introduced to reflect video content characteristics and distortions caused by compression and transmission and were obtained directly in parsing mode without decoding the pixel information in macro-blocks. Based on the features, an artificial neural network model was trained for perceptual quality prediction. In the second piece of work, a perceptual video quality prediction model is trained based on massive subjective test results. Prediction of perceptual quality is achieved through a decision tree using a set of easily calculated features from the compressed bitstream and the network. Moreover, based on the prediction model, a novel Forward Error Correction (FEC) scheme is introduced to protect video packets by taking into consideration video content characteristics, compression parameters, as well as network condition. Given a perceptual quality requirement, the error control scheme adjusts the level of protection for different components in a video stream such that the network overhead needed for transmission is minimized. In the third piece of work, a study was conducted to examine whether the previous prediction model could provide a good confidence measure in a different domain of judgments. The accuracy of judgements demonstrated the predictive validity of confidence measure with respect packet loss ratio traits. The results of this study were consistent with the previous one and the experiments suggested that brief and evaluative thin slice judgments are made relatively intuitively. Present research represents a new entry into the domain of high level judgments, such as video confidence measure by the use of our existing perception quality model.Item A Study of Inverter-Based Resources on Power Grid Operation Under Uncertain Operating Conditions(North Dakota State University, 2022) Maharjan, ManishaThe electric power grid is undergoing a rapid change predominantly driven by high penetration levels of renewable energy resources (RERs) such as wind and solar. These resources are interfaced with the power grid through power electronic inverters that use control algorithms to define their performance characteristics. As a group, these types of resources are commonly referred to as inverter-based RERs (IB-RERs). While IB-RERs use power electronic controls to change active and reactive power injection, the fast inverter controls, separating the power source from the grid, have changed grid dynamics and posed new challenges to maintaining reliable and safe grid operation. Moreover, the variable nature of IB-RERs generation under uncertain weather conditions further challenge the grid operation under uncertain operating conditions resulting from an imbalance in electricity generation and demand. To effectively manage IB-RERs for providing reliable grid services, this dissertation studies the impact of IB-RERs on grid operation at the transmission- and distribution- levels while considering uncertain operating conditions. More specifically, the probabilistic collocation method is introduced to quantify the uncertainty of renewable generation and load demands on the distribution system operation. Also, the probabilistic collocation method is integrated with grid assessment to assess the grid stiffness under uncertain operating conditions. In addition, the impact of transmission-level disturbances on solar generator operation in distribution systems is investigated by a real-time electromagnetic simulator. The proposed method and analysis results are useful for guiding grid planning and operation to address the emerging issues of integrating the high penetration of IB-RERs into the power grid for reliable grid services.Item Bit Optimized Reconfigurable Network (BORN): A New Pathway Towards Implementing a Fully Integrated Band-Switchable CMOS Power Amplifier(North Dakota State University, 2020) Hamidi Perchehkolaei, Seyyed BabakThe ultimate goal of the modern wireless communication industry is the full integration of digital, analog, and radio frequency (RF) functions. The most successful solution for such demands has been complementary metal oxide semiconductor (CMOS) technology, thanks to its cost-effective material and great versatility. Power amplifier (PA), the biggest bottleneck to integrate in a single-chip transceiver in wireless communications, significantly influences overall system performance. Recent advanced wireless communication systems demand a power amplifier that can simultaneously support different communication standards. A fully integrated single-chip tunable CMOS power amplifier is the best solution in terms of the cost and level of integration with other functional blocks of an RF transceiver. This work, for the first time, proposes a fully integrated band-switchable RF power amplifier by using a novel approach towards switching the matching networks. In this approach, which is called Bit Optimized Reconfigurable Network (BORN), two matching networks which can be controlled by digital bits will provide three operating frequency bands for the power amplifier. In order to implementing the proposed BORN PA, a robust high-power RF switch is presented by using resistive body floating technique and 6-terminal triple-well NMOS. The proposed BORN PA delivers measured saturated output power (Psat) of 21.25/22.25/ 23.0dBm at 960MHz/1317MHz/1750MHz, respectively. Moreover, the proposed BORN PA provides respective 3-dB bandwidth of 400MHz/425MHz/550MHz, output 1-dB compression point (P1dB) of 19.5dBm/20.0dBm/21.0dBm, and power-added efficiency (PAE) of 9/11/13% at three targeted frequency bands, respectively. The promising results show that the proposed BORN PA can be a practical solution for RF multiband applications in terms of the cost and level of integration with other functional blocks of an RF transceiver.