Electrocardiography (ECG) signal transmitter is the device used to transmit the electrical signals of the heart to the remote machine. These electrical signals are ECG signals caused due to electrical activities in the heart. ECG signals have very low amplitude and frequency; hence amplification of the signals is needed to strengthen the signal. Conversion of the amplified signal into digital information and transmitting that information without losing any data is the key. This information is further used in monitoring the heart.
In situations where information infrastructure is destroyed or not available, on-demand information infrastructure is pivotal for the success of rescue missions. In this paper, a drone-carried on demand information infrastructure for long-distance WiFi transmission system is developed. It can be used in the areas including emergency response, public event, and battlefield. The WiFi network can be connected to the Internet to extend WiFi access to areas where WiFi and other Internet infrastructures are not available. In order to establish a local area network to propagate WIFI service, directional antennas and wireless routers are used to create it. Due to unstable working condition on the flying drones, a precise heading turning stage is designed to maintain the two directional antennas facing to each other. Even if external interferences change the heading of the drones, the stages will automatically rotate back to where it should be to offset the bias. Also, to maintain the same flying altitude, a ground controller is designed to measure the height of the drones so that the directional antennas can communicate to each other successfully. To verify the design of the whole system, quite a few field experiments were performed. Experiments results indicates the design is reliable, viable and successful. Especially at disaster areas, it’ll help people a lot.
Environmental factors can have a significant impact on an individual's health and well-being, and a primary characteristic of environments is air quality. Air sensing equipment is available to the public, but it is often expensive,stationary, or unusable for persons without technical expertise. The goal of this project is to develop an inexpensive and portable sensor module for public use. The system is capable of measuring temperature in Celsius and Fahrenheit, heat index, relative humidity, and carbon dioxide concentration. The sensor module, referred to as the "sniffer," consists of a printed circuit board that interconnects a carbon dioxide sensor, a temperature/humidity sensor, an Arduino microcontroller, and a Bluetooth module. The sniffer is small enough to be worn as a pendant or a belt attachment, and it is rugged enough to consistently collect and transmit data to a user's smartphone throughout their workday. The accompanying smartphone app uses Bluetooth and GPS hardware to collect data and affix samples with a time stamp and GPS coordinates. The accumulated sensor data is saved to a file on the user's phone, which is then examined on a standard computer.
In the past few years, the study of electrical activity in the brain and its interactions with the body has become popular among researchers. One of the hottest topics related to brain activity is the epileptic seizure prediction. Currently, there are several techniques on how to predict a seizure; however, most of the techniques found in research papers are just mathematical models and not system implementations. The seizure prediction approach proposed in this thesis paper is achieved using the EMOTIV Epoc+ headset, MATLAB, and LabVIEW as the analog and digital signal processing devices. In addition, this thesis project incorporates the use of the Hilbert Huang transform (HHT) method to obtain intrinsic mode functions (IMF) and instantaneous frequency components of the transform. From the IMFs, features as variation coefficient (VC) and fluctuation indexes (FI) are extracted to feed a support vector machine that classifies the EEG data as pre-ictal and non-ictal EEGs. Outstanding patterns in non-ictal and pre-ictal are observed and demonstrated by significant differences between both types of EEG signals. In other words, a classification of EEG signals according to a category can be achieved proving that an epileptic seizure prediction technology has a future in engineering and biotechnology fields.
Through this research, engineering students and conservation biologists constructed an off-grid video system for observing western burrowing owls in El Paso, Texas. The burrowing owl has a declining population and their range decreasing, driving scientists' interest to see inside the den for observing critical nesting behavior. Texas Parks and Wildlife Department (TPWD) biologists wanted videos from inside the dark, isolated hillside owl burrows. This research yielded a replicable multi-camera prototype, empowering others to explore applications of engineering and wildlife monitoring. The remote station used an off-the-shelf video recording system, solar panels, charge controller, and lead acid batteries. Four local K-12 science educators participated in system testing at Lake Ray Roberts State Park through the Research Experiences for Teachers (RET, NSF #1132585) program, as well as four undergraduate engineering students as senior design research.
This thesis dissertation mainly compares and investigates laboratory study of different implementation methodologies of applied control systems and how they can be adopted in industrial, as well as commercial, automation applications. Namely the research paper aims to assess or evaluate eventual feedback control loops' performance and robustness over multiple conventional or state-of-the-art technologies in the field of applied industrial automation and instrumentation by implementing a laboratory case study setup: the ball on beam system. Hence, the paper tries to close the gap between industry and academia by: first, conducting a historical study and background information of main evolutional and technological eras in the field of industrial process control automation and instrumentation. Then, some related basic theoretical as well as practical concepts are reviewed in Chapter 2 of the report before displaying the detailed design. After that, the next Chapter, analyses the ball on beam control system problem as the case studied in the context of this research through reviewing previous literature, modeling and simulation. The following Chapter details the proposed design and implementation of the ball on beam case study as if it is under the introduced distributed industrial automation architecture. Finally, Chapter 5 concludes this work by listing several points leaned, remarks, and observations, and stating possible development and the future vision of this research.
Water scarcity for agriculture is one of the most important challenges to improve food security worldwide. In this thesis we study the potential to develop a low-cost controller for a small scale brackish desalination plant that consists of proven water treatment technologies, reverse osmosis, cation exchange, and nanofiltration to treat groundwater into two final products: drinking water and irrigation water. The plant is powered by a combination of wind and solar power systems. The low-cost controller uses Arduino Mega, and Arduino DUE, which consist of ATmega2560 and Atmel SAM3X8E ARM Cortex-M3 CPU microcontrollers. These are widely used systems characterized for good performance and low cost. However, Arduino also requires drivers and interfaces to allow the control and monitoring of sensors and actuators. The thesis explains the process, as well as the hardware and software implemented.
In today’s fast paced world, as the number of stations of television programming offered is increasing rapidly, time accessible to watch them remains same or decreasing. Sports videos are typically lengthy and they appeal to a massive crowd. Though sports video is lengthy, most of the viewer’s desire to watch specific segments of the video which are fascinating, like a home-run in a baseball or goal in soccer i.e., users prefer to watch highlights to save time. When associated to the entire span of the video, these segments form only a minor share. Hence these videos need to be summarized for effective presentation and data management. This thesis explores the ability to extract highlights automatically using MPEG-7 features and hidden Markov model (HMM), so that viewing time can be reduced. Video is first segmented into scene shots, in which the detection of the shot is the fundamental task. After the video is segmented into shots, extraction of key frames allows a suitable representation of the whole shot. Feature extraction is crucial processing step in the classification, video indexing and retrieval system. Frame features such as color, motion, texture, edges are extracted from the key frames. A baseball highlight contains certain types of scene shots and these shots follow a particular transition pattern. The shots are classified as close-up, out-field, base and audience. I first try to identify the type of the shot using low level features extracted from the key frames of each shot. For the identification of the highlight I use the hidden Markov model using the transition pattern of the shots in time domain. Experimental results suggest that with reasonable accuracy highlights can be extracted from the video.
As the technology is advances the reduced size of hardware gives rise to an additive 1/f baseband noise. This additive 1/f noise is a system noise generated due to miniaturization of hardware and affects the lower frequencies. Though 1/f noise does not show much effect in wide band channels because of its nature to affect only certain frequencies, 1/f noise becomes a prominent in OFDM communication systems where narrow band channels are used. in this thesis, I study the effects of 1/f noise on the OFDM systems and implement algorithms for estimation and suppression of the noise using Kalman filter. Suppression of the noise is achieved by subtracting the estimated noise from the received noise. I show that the performance of the system is considerably improved by applying the 1/f noise suppression.
A bidirectional two-hop relay network with decode-and-forward strategy is implemented using GNU Radio (software) and several USRPs (hardware) on Ubuntu (operating system). The relay communication system is comprised of three nodes; Base Station A, Base Station B, and Relay Station (the intermediate node). During the first time slot, Base Station A and Base Station B will each transmit data, e.g., a JPEG file, to Relay Station using DBPSK modulation and FDMA. For the final time slot, Relay Station will perform a bitwise XOR of the data, and transmit the XORed data to Base Station A and Base Station B, where the received data is decoded by performing another XOR operation with the original data.
Electrocardiography (ECG) monitor is a medical device for recording the electrical activities of the heart using electrodes placed on the body. There are many ECG monitors in the market but it is essential to find the accuracy with which they generate results. Accuracy depends on the processing of the ECG signal which contains several noises and the algorithms used for detecting peaks. Based on these peaks the abnormality in the functioning of the heart can be estimated. Hence this thesis characterizes the ECG signal which helps to detect the abnormalities and determine the accuracy of the system.
GNU Radio and OSSIE (Open-Source SCA (Software communication architecture) Implementation-Embedded) are two open source software toolkits for SDR (Software Defined Radio) developments, both of them can be supported by USRP (Universal Software Radio Peripheral). In order to compare the performance of these two toolkits, an FM receiver over GNU Radio and OSSIE are tested in my thesis, test results are showed in Chapter 4 and Chapter 5. Results showed that the FM receiver over GNU Radio has better performance, due to the OSSIE is lack of synchronization between USRP interface and the modulation /demodulation components. Based on this, the SISO (Single Input Single Output) communication system over GNU Radio is designed to transmit and receive sound or image files between two USRP equipped with RFX2400 transceiver at 2.45G frequency. Now, GNU Radio and OSSIE are widely used for academic research, but the future work based on GNU Radio and OSSIE can be designed to support MIMO, sensor network, and real time users etc.
Channel diversity techniques are effective ways to combat channel fading and noise in communication systems. In this thesis, I compare the performance of source and channel diversity techniques on fading and symmetric continuous channels. My experiments suggest that when SNR is low, channel diversity performs better, and when SNR is high, source diversity shows better performance than channel diversity.
Mobility models serve as the foundation for evaluating and designing airborne networks. Due to the significant impact of mobility models on the network performance, mobility models for airborne networks (ANs) must realistically capture the attributes of ANs. In this paper, I develop a comprehensive modeling framework for ANs. The work I have done is concluded as the following three parts. First, I perform a comprehensive and comparative analysis of AN mobility models and evaluate the models based on several metrics: 1) networking performance, 2) ability to capture the mobility attributes of ANs, 3) randomness levels and 4) associated applications. Second, I develop two 3D mobility models and realistic boundary models. The mobility models follow physical laws behind aircraft maneuvering and therefore capture the characteristics of aircraft trajectories. Third, I suggest an estimation procedure to extract parameters in one of the models that I developed from real flight test data. The good match between the estimated trajectories and real flight trajectories also validate the suitability of the model. The mobility models and the estimation procedure lead to the creation of “realistic” simulation and evaluation environment for airborne networks.
In this thesis, I present my study on the impact of multi-group network structure on the performance of consensus building strategies, and the preliminary mathematical formulation of the problem on improving the performance of the National Airspace system (NAS) through long-term investment. The first part of the thesis is concerned with a structural approach to the consensus building problem in multi-group distributed sensor networks (DSNs) that can be represented by bipartite graph. Direct inference of the convergence behavior of consensus strategies from multi-group DSN structure is one of the contributions of this thesis. The insights gained from the analysis facilitate the design and development of DSNs that meet specific performance criteria. The other part of the thesis is concerned with long-term planning and development of the NAS at a network level, by formulating the planning problem as a resource allocation problem for a flow network. The network-level model viewpoint on NAS planning and development will give insight to the structure of future NAS and will allow evaluation of various paradigms for the planning problem.
This work presents a novel technique for data compression based on multi-residue number systems. The basic theorem is that an under-determined system of congruences could be solved to accomplish data compression for a signal satisfying continuity of its information content and bounded in peak-to -peak amplitude by the product of relatively prime moduli,. This thesis investigates this property and presents quantitative results along with MATLAB codes. Chapter 1 is introductory in nature and Chapter 2 deals in more detail with the basic theorem. Chapter 3 explicitly mentions the assumptions made and chapter 4 shows alternative solutions to the Chinese remainder theorem. Chapter 5 explains the experiments in detail whose results are mentioned in chapter 6. Chapter 7 concludes with a summary and suggestions for future work.
In the world of networked system, average consensus is an important dimension of co-ordinate control and cooperation. Since the communication medium is digital, real value cannot be transmitted and we need to perform quantization before data transmission. But for the quantization, error is introduced in exact value and initial average is lost. Based on this limitation, my 16 bit quantization method (sending MSB in 1-4 cycle and MSB+LSB in 5th cycle) reduces error significantly and preserves initial average. Besides, it works on all types of graphs (star, complete, ring, random geometric graph). My other algorithm, distributing averaging algorithm (PQDA) with probabilistic quantization also works on random geometric graph, star, ring and slow co-herency graph. It shows significant reduced error and attain strict consensus.
The baluns are the key components in balanced circuits such balanced mixers, frequency multipliers, push–pull amplifiers, and antennas. Most of these applications have become more integrated which demands the baluns to be in compact size and low cost. In this thesis, a new approach about the design of planar balun is presented where the 4-port symmetrical network with one port terminated by open circuit is first analyzed by using even- and odd-mode excitations. With full design equations, the proposed balun presents perfect balanced output and good input matching and the measurement results make a good agreement with the simulations. Second, Yagi-Uda antenna is also introduced as an entry to fully understand the quasi-Yagi antenna. Both of the antennas have the same design requirements and present the radiation properties. The arrangement of the antenna’s elements and the end-fire radiation property of the antenna have been presented. Finally, the quasi-Yagi antenna is used as an application of the balun where the proposed balun is employed to feed a quasi-Yagi antenna. The antenna is working in the S-band radio frequency and achieves a measured 36% fractional bandwidth for return loss less than -10 dB. The antenna demonstrates a good agreement between its measurement and simulation results. The impact of the parasitic director on the antenna’s performance is also investigated. The gain and the frequency range of the antenna have been reduced due to the absence of this element. This reduction presents in simulation and measurement results with very close agreement.
Since its invention, phased array has been extensively applied in both military and civil areas. The applications include target detecting and tracking, space probe communication, broadcasting, human-machine interfaces, and remote sensing. Although the phased array applications show a broad range of potential market, there are some limitations of phased array's development: high cost, complex structure, narrow bandwidth, and high power consumption. Therefore, novel ideas are needed to reduce these constraints. In this thesis, several new approaches about the design and application of phased array are presents. First, the principle of phased array and fundamental design equations are introduced. Second, a new application of phased array antenna for radar respiration measurement is presented. By integrating a 4×4 Butler matrix with four-element antenna array, there will be four distinct main beams in radiation pattern. This new approach can improve the measurement accuracy and realize a high detecting rate. Third, a compact phased array antenna system based on dual-band operations is introduced. Dual-band function can make N-antenna system obtain 2N unique radiation beams (N is an integer) and achieve a significant size reduction compared to the conventional single-band system. To verify the design concept, a four-element phased array antenna working at 5GHz and 8GHz is designed and fabricated. The measurement results make a good agreement with the simulations. Finally, a novel architecture of steering phase feeding network by using bi-directional series-fed topology is presented. This bi-directional series-fed network needs less phase shifters and realizes steering phase function by applying control voltage.
The thesis implements a vision-based leader-follower tracking algorithm on a ground robot system. One camera is the only sensor installed the leader-follower system and is mounted on the follower. One sphere is the only feature installed on the leader. The camera identifies the sphere in the openCV Library and calculates the relative position between the follower and leader using the area and position of the sphere in the camera frame. A P controller for the follower and a P controller for the camera heading are built. The vision-based leader-follower tracking algorithm is verified according to the simulation and implementation.
The thesis deals with the design and implementation of broadband and narrowband antennas and their applications in practical environment. In this thesis, a new concept for designing the UWB antenna is proposed based on the CRLH metamaterials and this UWB antenna covers a frequency range from 2.45 GHz to 11.6 GHz. Based on the design of the UWB antenna, another antenna is developed that can cover a very wide bandwidth i.e from 0.66 GHz to 120 GHz. This antenna can not only be used for UWB applications but also for other communication systems working below the UWB spectrum such as GSM, GPS, PCS and Bluetooth. The proposed antenna covering the bandwidth from 0.66 GHz to 120 GHz is by far the largest bandwidth antenna developed based on metamaterials. Wide band antennas are not preferred for sensing purpose as it is difficult to differentiate the received signals. A multiband antenna which can be used as a strain sensor for structural health monitoring is proposed. The idea is to correlate the strain applied along the length or width with the multiple resonant frequencies. This gives the advantage of detecting the strain applied along any direction (either length or width), thus increasing the sensing accuracy. Design and application of a narrow-band antenna as a temperature sensor is also presented. This sensor can be used to detect very high temperature changes (>10000C). This sensor does not require a battery, can be probed wirelessly, simple and can be easily fabricated, can withstand harsh environmental conditions.
This thesis deals with the decentralized autonomous system, in which individual nodes acting like peers, communicate and participate in collaborative tasks and decision making processes. An experimental test-bed is created using four Garcia robots. The robots act like peers and interact with each other using user datagram protocol (UDP) messages. Each robot continuously monitors for messages coming from other robots and respond accordingly. Each robot broadcasts its location to all the other robots within its vicinity. Robots do not have built-in global positioning system (GPS). So, an indoor localization method based on signal strength is developed to estimate robot's position. The signal strength that the robot gets from the nearby wireless access points is used to calculate the robot's position. Trilateration and fingerprint are some of the indoor localization methods used for this purpose. The communication functionality of the decentralized system has been tested and verified in the autonomous systems laboratory.
This thesis discusses the design, fabrication, and testing of a high efficiency, dual band radio frequency power amplifier. While it is difficult to demonstrate an exact mode of operation for power amplifiers at radio frequencies, based on the characteristics of the transistor itself, the argument can be made that our high efficiency performance is due to an approximation to class E operation. The PA is designed around a CGH40025 transistor manufactured by Cree, Inc, which has developed a very useful nonlinear model of its transistor, which allows use of software load/source pull methods to determine optimum impedances to be presented to the gate and drain (hereafter referred to as source and load) of the transistor at each band of operation. A recent work on dual-band impedance matching is then used to design distributed element networks in order to present conjugate matches of these impedances to the transistor. This is followed by a careful layout, after which the PA is then fabricated on a low-impedance substrate using a LPKF Protomat S63 rapid prototyping machine. Measurements of gain and drain current provide values for power-added-efficiency. Simulated gains were 21 and 18 dB at 800 MHz and 1.85 GHz, respectively, with PAE around 63% for both bands. Measurements taken from the fabricated PA showed gains of 20 and 16 dB at each band, but PAE of 80% at 800 MHz and 43% at 1.85 GHz.
A conventional RF power amplifier will convert the low powered radio frequency signals into high powered signals. Along with the expected ability to increase the communication distance, data transfer rates, RF power amplifiers also have many applications which include military radar system, whether forecasting, etc. The main objective of any power amplifier research is to increase the efficiency while maintaining linearity and broadening the frequency of operation. The main motivation for the renewed interest in PA technology comes from the technical challenges and the economics of modern digital communication systems. Modern communications require high linear power amplifiers and in order to reduce the complete system cost, it is necessary to have a single broadband power amplifier, which can amplify multiple carriers. The improvement in the efficiency of the power amplifier increases the battery life and also reduces the cooling requirements for the same output power. In this thesis, I aim to design and build a wideband class J power amplifier suitable for modern communications. For wideband operation of the GaN technology PA, a bandwidth extension design method is studied and implemented. The simulation results are proved to have a good argument with the theoretical calculations.
Piezoelectricity crystal is used in different area in industry, such as downhole oil, gas industry, and ballistics. The piezoelectricity crystals are able to create electric fields due to mechanical deformation called the direct piezoelectric effect, or create mechanical deformation due to the effect of electric field called the indirect piezoelectric effect. In this thesis, piezoelectricity effect is the core part. There are 4 parts in the frequency output pressure transducer: two crystal oscillators, phase-locked loop (PLL), mixer, frequency counter. Crystal oscillator is used to activate the piezoelectricity crystal which is made from quartz. The resonance frequency of the piezoelectricity crystal will be increased with the higher pressure applied. The signal of the resonance frequency will be transmitted to the PLL. The function of the PLL is detect the frequency change in the input signal and makes the output of the PLL has the same frequency and same phase with the input signal. The output of the PLL will be transmitted to a Mixer. The mixer has two inputs and one output. One input signal is from the pressure crystal oscillator and another one is from the reference crystal oscillator. The frequency difference of the two signal will transmitted to the frequency counter from the output of the mixer. Thus, the frequency output pressure transducer with a frequency counter is a portable device which is able to measure the pressure without oscilloscope or computer.
Multi band technology helps in getting multiple operating frequencies using a single microwave device. This thesis presents the design of dual and tri band microwave devices using coupled transmission line structures. Chapter 2 presents the design of a novel dual band transmission line structure using coupled lines. In chapter 3, Design of a dual band branch line coupler and a dual band Wilkinson power divider are proposed using the novel dual band transmission line structure presented in the previous chapter. In chapter 4, Design of a tri band transmission line structure by extending the dual band structure is presented. The Conclusion and future work are presented in chapter 5.
With the rapid development of the modern technology, radio frequency and microwave systems are playing more and more important roles. Since the time the first microwave device was invented, they have been leading not only the military but also our daily life to a new era. In order to make the devices have more practical applications, more and more strict requirements have been imposed. For example, good adaptability, reduced cost and shrank size are highly required. In this thesis, three devices are designed based on this requirement. At first, a symmetric four-port microwave varactor based 90-degree directional coupler with tunable coupling ratios and reconfigurable responses is presented. The proposed coupler is designed based on the modified structure of a crossover, where varactors are loaded. Then, a novel reconfigurable 3-dB directional coupler is presented. Varactors and inductors are loaded to the device to realize the reconfigurable performance. By adjusting the voltage applied to the varactors, the proposed coupler can be reconfigured from a branch-line coupler (90-degree coupler) to a rat-race coupler (180 degree coupler) and vice versa. At last, two types (Type-I and Type-II) of microwave baluns with generalized structures are presented. Different from the conventional transmission-line-based baluns where λ/2 transmission lines or λ/4 coupled lines are used, the proposed baluns are constructed by transmission lines with arbitrary electrical lengths.
CGRAs (coarse grained reconfigurable array architectures) try to ﬁll the gap between FPGAs and ASICs. Over three decades, the research towards CGRA design has produced number of architectures. Each of these designs lie at diﬀerent points on a line drawn between FPGAs and ASICs, depending on the tradeoﬀs and design choices made during the design of architectures. Thus, design space exploration (DSE) takes a very important role in the circuit design process. In this work I propose the design space exploration of CGRAs can be done quickly and eﬃciently through crowd-sourcing and a game driven approach based on an interactive mapping game UNTANGLED and a design environment called SmartBricks. Both UNTANGLED and SmartBricks have been developed by our research team at Reconfigurable Computing Lab, UNT. I present the results of design space exploration of domain-specific reconfigurable architectures and compare the results comparing stripe vs mesh style, heterogeneous vs homogeneous. I also compare the results obtained from diﬀerent interconnection topologies in mesh. These results show that this approach oﬀers quick DSE for designers and also provides low power architectures for a suite of benchmarks. All results were obtained using standard cell ASICs with 90 nm process.
Multimedia environmental monitoring involves capturing valuable visual and audio information from the field station. This will permit the environmentalists and researchers to analyze the habitat and vegetation of a region with respect to other environmental specifics like temperature, soil moisture, etc. This thesis deals with the development of a test bed for multimedia monitoring by capturing image information and making it available for the public. A USB camera and a Single board computer are used to capture images at a specified frequency. A web-client is designed to display the image data and establish a secured remote access to reconfigure the field station. The development includes two modes of image acquisition including a basic activity recognition algorithm. Good quality images are captured with the cost for development of the system being less than 2 hundred dollars.
Semiconductor nanowires acts as an emerging class of materials with great potential for applications in future electronic devices. Small size, large surface to volume ratio and high carrier mobility of nanowires make them potentially useful for electronic applications with high integration density. In this thesis, the focus was on the growth of high quality ZnO nanowires, fabrication of field effect transistors and UV- photodetectros based on them. Intrinsic nanowire parameters such as carrier concentration, field effect mobility and resistivity were measured by configuring nanowires as field effect transistors. The main contribution of this thesis is the development of a high gain UV photodetector. A single ZnO nanowire functioning as a UV photodetector showed promising results with an extremely high spectral responsivity of 120 kA/W at wavelength of 370 nm. This corresponds to high photoconductive gain of 2150. To the best of our knowledge, this is the highest responsivity and gain reported so far, the previous values being responsivity=40 kA/W and gain=450. The enhanced photoconductive behavior is attributed to the presence of surface states that acts as hole traps which increase the life time of photogenerated electrons raising the photocurrent. This work provides the evidence of such solid states and preliminary results to modify the surface of ZnO nanowire is also produced.
Crystalline indium oxide nanowires were synthesized following optimization of growth parameters. Oxygen vacancies were found to impact the optical and electronic properties of the as-grown nanowires. Photoluminescence measurements showed a strong U.V emission peak at 3.18 eV and defect peaks in the visible region at 2.85 eV, 2.66 eV and 2.5 eV. The defect peaks are attributed to neutral and charged states of oxygen vacancies. Post-growth annealing in oxygen environment and passivation with sulphur are shown to be effective in reducing the intensity of the defect induced emission. The as-grown nanowires connected in an FET type of configuration shows n-type conductivity. A single indium oxide nanowire with ohmic contacts was found to be sensitive to gas molecules adsorbed on its surface.
An economically reliable technique for the synthesis of silicon nanowire was developed using silicon chloride as source material. The 30-40 micron long nanowires were found to have diameters ranging from 40 – 100 nm. An amorphous oxide shell covered the nanowires, post-growth. Raman spectroscopy confirmed the composition of the shell to be silicon-dioxide. Photoluminescence measurements of the as-grown nanowires showed green emission, attributed to the presence of the oxide shell. Etching of the oxide shell was found to decrease the intensity of green emission. n-type doping of the silicon nanowires was achieved using antimony as the dopant. The maximum dopant concentration was achieved by post-growth diffusion. Intrinsic nanowire parameters were determined by implementation of the as-grown and antimony doped silicon nanowires in field effect transistor configuration.
This thesis describes development of low cost indoor air quality (IAQ) monitoring system for research. It describes data collection of various parameters concentration present in indoor air and sends data back to host PC for further processing. Thesis gives detailed information about hardware and software implementation of IAQ monitoring system. Also discussed are building wireless ZigBee network, creating user friendly graphical user interface (GUI) and analysis of obtained results in comparison with professional benchmark system to check system reliability. Throughputs obtained are efficient enough to use system as a reliable IAQ monitor.
In general, Dual-Band technology enables microwave components to work at two different frequencies. This thesis introduces novel dual-band microwave components and their applications. Chapter 2 presents a novel compact dual-band balun (converting unbalanced signals to balanced ones). The ratio between two working frequencies is analyzed. A novel compact microstrip crossover (letting two lines to cross each other with very high isolation) and its dual-band application is the subject of chapter 3. A dual-frequency cloak based on lumped LC-circuits is introduced in chapter 4. In chapter 5, a dual-band RF device to detect dielectric constant changes of liquids in polydimethylsiloxane (PDMS) microfluidic channels has been presented. Such a device is very sensitive, and it has significantly improved the stability. Finally, conclusion of this thesis and future works are given in chapter 6.
This thesis presents a brief introduction to microwave components and technology. It also presents two novel dual-band designs, their analysis, topology, simulation and fabrication. In chapter 2, a novel dual-band bandpass filter using asymmetric stub-loaded stepped-impedance resonators (SLSIRs) operating at 1 and 2.6 GHz is shown. This type of design applies suitable arrangements to improve the filter’s performance. Then, in chapter 3, a novel dual-band balun (transforms unbalanced input signals to balanced output signals or vice versa) operating at 1.1 and 2 GHz with flexible frequency ratios is presented, which has more advantages in microwave applications. Then, conclusion and future works are discussed in chapter 4.
The thesis represents the design for dual-band quarter wavelength and half wavelength microstrip transmission line. Chapter 2 proposed the design of a novel dual-band asymmetric pi-shaped short-circuited quarter wavelength microstrip transmission line working at frequencies 1GHz and 1.55 GHz for 50Ω transmission line and at frequencies 1GHz and 1.43GHz for 60Ω transmission line. Chapter 3 proposed the design of a novel dual-band quarter wavelength microstrip transmission line with asymmetrically allocated open stubs and short-circuited stubs working at frequencies 1GHz and 1.32GHz. Chapter 4 proposed the design of dual-band pi-shaped open stub half wavelength microstrip transmission line working at frequencies 1GHz and 2.07GHz. Numerical simulations are performed both in HyperLynx 3D EM and in circuit simulator ADS for all of the proposed designs to measure the return loss (S11) and insertion loss (S12) in dB and phase response for S12 in degree.
A technique is proposed to improve the accuracy of indoor positioning systems based on WIFI radio-frequency signals by using dynamic access points and fingerprints (DAFs). Moreover, an indoor position system that relies solely in DAFs is proposed. The walking pattern of indoor users is classified as dynamic or static for indoor positioning purposes. I demonstrate that the performance of a conventional indoor positioning system that uses static fingerprints can be enhanced by considering dynamic fingerprints and access points. The accuracy of the system is evaluated using four positioning algorithms and two random access point selection strategies. The system facilitates the location of people where there is no wireless local area network (WLAN) infrastructure deployed or where the WLAN infrastructure has been drastically affected, for example by natural disasters. The system can be used for search and rescue operations and for expanding the coverage of an indoor positioning system.
Wireless sensor networks (WSNs) have gained attention in recent years with the proliferation of the micro-electro-mechanical systems, which has led to the development of smart sensors. Smart sensors has brought WSNs under the spotlight and has created numerous different areas of research such as; energy consumption, convergence, network structures, deployment methods, time delay, and communication protocols. Convergence rates associated with information propagations of the networks will be questioned in this thesis. Mobility is an expensive process in terms of the associated energy costs. In a sensor network, mobility has significant overhead in terms of closing old connections and creating new connections as mobile sensor nodes move from one location to another. Despite these drawbacks, mobility helps a sensor network reach an agreement more quickly. Adding few mobile nodes to an otherwise static network will significantly improve the network’s ability to reach consensus. This paper shows the effect of the mobility on convergence rate of the wireless sensor networks, through Eigenvalue analysis, modeling and simulation.
Currently, standards from government agencies such as the National Institute for Occupation Safety and Health exist to aid in safeguarding individuals’ capacity for hearing, but only in factory settings in which large machines often produce loud levels of sound. Neglecting the fact that these preventative measures are only in place in the most limited of settings, no system currently exists to observe and report sound exposure levels in a manner timely or easily recognizable enough to adequately serve its purpose of hearing conservation. Musicians may also incur significant levels of risk for hearing loss in their day-to-day rehearsals and concerts, from high school marching bands to university wind bands. As a result, music school accrediting organizations such as the National Association of Schools of Music and even the European Union have begun taking steps meant to determine the risks associated with music. To meet these goals and improve upon current technologies, a system has been developed that electronically records sound levels utilizing modern hardware, increases the speed of reporting by transmitting data over computer networks and the Internet, and displays measures calculated from these data in a web browser for a highly viewable, user-friendly interface.
Optical current sensors (OCSs) are initially developed to measure relatively large current over a wide range of frequency band. They are also used as protective devices in the event a fault occurs due to a short circuit, in the power generation and distribution industries. The basic principal used in OCS is the Faraday effect. When a light guiding faraday medium is placed in a magnetic field which is produced by the current flowing in the conductor around the magnetic core, the plane of polarization of the linearly polarized light is rotated. The angle of rotation is proportional to the magnetic field strength, proportionality constant and the interaction length. The proportionality constant is the Verdet constant V (λ, T), which is dependent on both temperature and wavelength of the light. Opto electrical methods are used to measure the angle of rotation of the polarization plane. By measuring the angle the current flowing in the current carrying conductor can be calculated. But the accuracy of the OCS is lost of the angle of rotation of the polarization plane is dependent on the Verdet constant, apart from the magnetic field strength. As temperature increases the Verdet constant decreases, so the angle of rotation decreases. To compensate the effect of temperature on the OCS, a new method has been proposed. The current and temperature are measured with the help of a duel frequency method. To detect the line current in the conductor or coil, a small signal from the line current is fed to the reference of the lock in. To detect the temperature, the coil is excited with an electrical signal of a frequency different from the line frequency, and a small sample of this frequency signal is applied to the reference of the lock in. The temperature and current readings obtained are ...
Coarse-grained fabrics are comprised of multi-bit configurable logic blocks and configurable interconnect. This work is focused on area and energy optimization techniques for coarse-grained reconfigurable fabric architectures. In this work, a variety of design techniques have been explored to improve the utilization of computational resources and increase energy savings. This includes splitting, folding, multi-level vertical interconnect. In addition to this, I have also studied fully connected homogeneous and heterogeneous architectures, and 3D architecture. I have also examined some of the hybrid strategies of computation unit’s arrangements. In order to perform energy and area analysis, I selected a set of signal and image processing benchmarks from MediaBench suite. I implemented various fabric architectures on 90nm ASIC process from Synopsys. Results show area improvement with energy savings as compared to baseline architecture.
This thesis presents the rate distortion analysis of conditional motion estimation, a process in which motion computation is restricted to only active pixels in the video. We model active pixels as independent and identically distributed Gaussian process and inactive pixels as Gaussian-Markov process and derive the rate distortion function based on conditional motion estimation. Rate-Distortion curves for the conditional motion estimation scheme are also presented. In addition this thesis also presents the hardware implementation of a block based motion estimation algorithm. Block matching algorithms are difficult to implement on FPGA chip due to its complexity. We implement 2D-Logarithmic search algorithm to estimate the motion vectors for the image. The matching criterion used in the algorithm is Sum of Absolute Differences (SAD). VHDL code for the motion estimation algorithm is verified using ISim and is implemented using Xilinx ISE Design tool. Synthesis results for the algorithm are also presented.
As science and technology continue to advance, innovative developments in transportation can enhance product safety and security for the benefit and welfare of society. The federal government requires every commercial truck to be inspected before each trip. This pre-trip inspection ensures the safe mechanical condition of each vehicle before it is used. An Unmanned Aerial Vehicle (UAV) could be used to provide an automated inspection, thus reducing driver workload, inspection costs and time while increasing inspection accuracy. This thesis develops a primary component of the algorithm that is required to implement UAV pre-trip inspections for commercial trucks using an android-based application. Specifically, this thesis provides foundational work of providing stable height control in an outdoor environment using a laser sensor and an android flight control application that includes take-off, landing, throttle control, and real-time video transmission. The height algorithm developed is the core of this thesis project. Phantom 2 Vision+ uses a pressure sensor to calculate the altitude of the drone for height stabilization. However, these altitude readings do not provide the precision required for this project. Rather, the goal of autonomously controlling height with great precision necessitated the use of a laser rangefinder sensor in the development of the height control algorithm. Another major contribution from this thesis research is to extend the limited capabilities of the DJI software development kit in order to provide more sophisticated control goals without modifying the drone dynamics. The results of this project are also directly applicable to a number of additional uses of drones in the transportation industry.
This thesis provides an implementation of consensus of multi-agent networked systems. Consensus problem is an important issue of distributed computing and has various algorithms and applications in the field of electronical and computer science. The consensus requests all nodes of a network reach an agreement over a certain measurement. An algorithm of convergent consensus problem is implemented through a small network of Bluetooth communication in the thesis. The connections of the Bluetooth devices are wireless, and the device nodes of the network are driven by C++ software and Winsock API. The simulation results show that the implementation completes all the requirements of the distributed consensus algorithm.
This thesis investigates the design and implementation of turbo codes over the GNU radio. The turbo codes is a class of iterative channel codes which demonstrates strong capability for error correction. A software defined radio (SDR) is a communication system which can implement different modulation schemes and tune to any frequency band by means of software that can control the programmable hardware. SDR utilizes the general purpose computer to perform certain signal processing techniques. We implement a turbo coding system using the Universal Software Radio Peripheral (USRP), a widely used SDR platform from Ettus. Detail configuration and performance comparison are also provided in this research.
This thesis investigates the design and implementation of wireless communication system over the GNU Radio. Wireless applications are on the rise with advent of new devices, therefore there is a need to transfer the hardware complexity to software. This development enables software radio function with minimum hardware dependency. the purpose of this thesis is to design a system that will transmit compressed data via Software Defined Radio (SDR). Some parameters such as modulation scheme, bit rate can be changed to achieve the desired quality of service. in this thesis GNU (GNU’s not unix) radio is used while the hardware structure is Universal Software Radio Peripheral (USRP). in order to accomplish the goal, a compression technique called H264 (MPEG_4) encoding is applied for converting data into compressed format. the encoder was implemented in C++ to get compressed data. After encoding, the transmitter reads the compressed data and starts modulation. After modulation, the transmitter put the packets into USRP and sends it to the receiver. Once packets are received they are demodulated and then decoded to recover the original data.
This thesis describes environmental data collection and transmission from the field to a server using Wi-Fi. Also discussed are components, radio wave propagation, received power calculations, and throughput tests. Measured receive power resulted close to calculated and simulated values. Throughput tests resulted satisfactory. The thesis provides detailed systematic procedures for Wi-Fi radio link setup and techniques to optimize the quality of a radio link.
Integrated Circuits (ICs) have a broad range of applications in healthcare, military, consumer electronics etc. The acronym VLSI stands for Very Large Scale Integration and is a process of making ICs by placing millions of transistors on a single chip. Because of advancements in VLSI design technologies, ICs are getting smaller, faster in speed and more efficient, making personal devices handy, and with more features. In this thesis work an interactive framework is designed in which the fundamental concepts of digital logic design and VLSI design such as logic gates, MOS transistors, combinational and sequential logic circuits, and memory are presented in a simple, interactive and user friendly way to create interest in students towards engineering fields, especially Electrical Engineering and Computer Engineering. Most of the concepts are explained in this framework by taking the examples which we see in our daily lives. Some of the critical design concerns such as power and performance are presented in an interactive way to make sure that students can understand these significant concepts in an easy and user friendly way.
Network structure plays a significant role in determining the performance of network inference tasks. An interactive tool to study the dependence of network topology on estimation performance was developed. The tool allows end-users to easily create and modify network structures and observe the performance of pole estimation measured by Cramer-Rao bounds. The tool also automatically suggests the best measurement locations to maximize estimation performance, and thus finds its broad applications on the optimal design of data collection experiments. Finally, a series of theoretical results that explicitly connect subsets of network structures with inference performance are obtained.
This study is based on applying a non-linear mapping method, here the unscented Kalman filter; to estimate and optimize data rate resulting from the arrival rate having a Poisson distribution in an orthogonal frequency division multiplexing (OFDM) transmission system. OFDM is an emerging multi-carrier modulation scheme. With the growing need for quality of service in wireless communications, it is highly necessary to optimize resources in such a way that the overall performance of the system models should rise while keeping in mind the objective to achieve high data rate and efficient spectral methods in the near future. In this study, the results from the OFDM-TDMA transmission system have been used to apply cross-layer optimization between layers so as to treat different resources between layers simultaneously. The main controller manages the transmission of data between layers using the multicarrier modulation techniques. The unscented Kalman filter is used here to perform nonlinear mapping by estimating and optimizing the data rate, which result from the arrival rate having a Poisson distribution.
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