Department: Electrical Engineering (Engineering and Technology) ![[clear]](close-x.png "Remove this limiter")
83 matches in the database.
These are records: 1 - 30.
Did you mean instcode:ohio?
[1] [2] [3]
1.
Abbey, Sonja P.
Tolerance and Materials Design of Nanophotonic Amorphous Membranes for Broadband Chemical Sensing.
Degree: MS, Electrical Engineering (Engineering and Technology), 2012, Ohio University
► Very few if any gaseous chemical sensors are highly sensitive, highly selective,…
(more)
▼ Very few if any gaseous chemical sensors are highly sensitive, highly selective, applicable for sensing multiple chemicals, and allow for broad spectrum detection. There is a need for more sensitive, selective, and reliable chemical sensors in the market today. This thesis focuses on the materials and tolerance design of thin film Low Optical Overlapping Mode (LOOM) waveguides. Ellipsometry, atomic force microscopy, and xray diffraction tools are used to measure characteristics important to materials choice and design. RF magnetron sputtering and atomic layer deposition tools are evaluated and compared as options for thin film deposition. Through the use of FemSIMâ„¢ modeling software, tolerance values for membrane and rib thickness, membrane to rib ratio, and refractive index of the wave guiding material are defined. Additionally the broad spectrum capability of the waveguide is defined.
Advisors/Committee Members: Whaley, Ralph D.
Subjects: Electrical Engineering; Optics
Keywords: Tolerance; Materials; Design; Nanophotonic; Amorphous; Membranes; Broadband; Chemical; Sensing; optical; waveguide; multiple; LOOM; spectrum; absorption
More Like This
2.
Alhashim, Najeeb S.
Performance of Disparate-Bandwidth DS-SS Systems in Spectral Overlay Ad Hoc Networks.
Degree: MS, Electrical Engineering (Engineering and Technology), 2009, Ohio University
► In this thesis we investigate the performance of direct sequence spread spectrum(DS-SS)…
(more)
▼ In this thesis we investigate the performance of direct sequence spread spectrum(DS-SS) overlay ad hoc networks by performing computer simulations and numerical evaluations based upon mathematical analysis. Two such DS-SS systems, with different bandwidths, are studied. We investigate performance statistics for a terrestrial network model in a limited two-dimensional area, in which user (node) locations are random, and statistics are gathered over numerous realizations of these random node locations. For all users in both systems we collect statistics on performance in terms of signal-to-noiseplus-interference ratio (SNIR) and bit error probabilities, to illustrate aggregate behavior attainable in such systems. We first illustrate our technique for a specified reference system with a given set of parameters, then we vary several of these parameters to assess the effects on performance. Parameters we vary include transmit power, data rates,processing gain, path loss exponent and shadowing standard deviation. We demonstrate that overlay of different-bandwidth DS-SS systems in an ad hoc network can be practical by specifying appropriate system design parameters.
Advisors/Committee Members: Matolak, David W.
Subjects: Electrical engineering
Keywords: DS-SS Overlay; CDMA; Ad Hoc Networks
More Like This
3.
Allala, Prathyusha.
Genetic Optimization of Turbo Decoder.
Degree: MS, Electrical Engineering (Engineering and Technology), 2011, Ohio University
► The objective of this thesis is to improve the performance of the…
(more)
▼ The objective of this thesis is to improve the performance of the conventional turbo decoders by placing them inside an iterative loop which uses optimization techniques to correct codewords which fail to converge on the initial decoding pass. The increase in bit error and code word error rate performance of the decoder can be achieved by adding small noise increments to “mutate” the received signal in the direction of convergence. Optimization algorithm techniques are used to increase the bit error and code word error rate performance of the decoder. A conventional MAX-log-MAP algorithm is used to decode most codewords. Simple hill climbing and random restart hill climbing algorithms are used when decoder fails to converge on the initial decoding attempt. In this thesis the conventional turbo decoder has been studied via computer simulations by applying optimization algorithm techniques and by introducing small artificial noise increments to the input signal. Improvements of an order of magnitude in bit error rate are achieved.
Advisors/Committee Members: Dill, Jeffrey C.
Subjects: Electrical Engineering; Engineering; Technical Communication
Keywords: optimization algorithms; turbo codes
More Like This
4.
Al-Ouran, Rami R.
Linux Implementation of a New Model for Handling Task Dynamics in Proportional Share Based Scheduling Systems.
Degree: MS, Electrical Engineering (Engineering and Technology), 2010, Ohio University
► Proportional Share Scheduling (PSS) algorithms have two characteristics that make them attractive…
(more)
▼ Proportional Share Scheduling (PSS) algorithms have two characteristics that make them attractive to be used in a scheduling design: flexibility and fairness. To support time sensitive tasks a new feature should be added to the PSS design which is reservation guarantee. A number of PSS algorithms have been introduced to add that feature. Earliest Eligible Virtual Deadline First (EEVDF) is a PSS based algorithm that succeeded in integrating flexibility and fairness along with reservation guarantee. The main feature of EEVDF is ensuring that the difference between the service time the task should receive in an ideal system and the service time it actually receives is bounded at all times which makes reservation guarantee possible. In this thesis a new model based on the EEVDF algorithm was implemented to dynamically support a mix of applications with different requirements in a seamless manner. These applications include time-sensitive applications, time sensitive applications with added benefit and regular applications. The new model also adds more flexibility to the original EEVDF model especially for handling system dynamics. This new model was implemented as a loadable kernel module which makes debugging and improving the model easier and more efficient.
Advisors/Committee Members: Drews, Frank.
Subjects: Computer science
Keywords: pss; proportional share scheduling; task dynamics; linux
More Like This
5.
Althaus, Joseph H.
An Embedded Nonlinear Control Implementation for a Hovering Small Unmanned Aerial System.
Degree: MS, Electrical Engineering (Engineering and Technology), 2010, Ohio University
► This thesis presents the design, development, and experimental verification of an embedded…
(more)
▼ This thesis presents the design, development, and experimental verification of an embedded vehicle controller applied to a hovering small unmanned aerial system dubbed the UFO. The effort demonstrated the feasibility of implementation of advanced nonlinear controller designs in embedded hardware to achieve increased system performance. Furthermore, it was shown that the controller implementation was not penalized due to size, weight, and power build-up typically associated with vehicles in this class. Performance was verified experimentally through simulation case studies that subjected the vehicle and embedded controller to various real-world considerations. Finally, justification of approach occurred through analysis of the experimental results.
Advisors/Committee Members: Zhu, J. Jim.
Subjects: Electrical engineering; Engineering
Keywords: VTOL aircraft; embedded systems; nonlinear control; flight controller; trajectory linearization
More Like This
6.
Anitei, Irina.
Circular Trellis based Low Density Parity Check Codes.
Degree: MS, Electrical Engineering (Engineering and Technology), 2008, Ohio University
► Tail biting circular trellis block codes (TBC)2 used along with iterative Maximum…
(more)
▼ Tail biting circular trellis block codes (TBC)2 used along with iterative Maximum A-Posteriori (MAP) decoders achieve performance very close to the Shannon limit. A Low Density Parity Check (LDPC) code using a Sum Product Algorithm (SPA) decoder is also known to achieve comparable performance. In this work the performance of (TBC)2 encoder used with an SPA decoder is presented. The goal of this research is to compare the performance of (TBC)2 encoder with different iterative decoders.In order to use the SPA for decoding, a parity check (H) matrix representation of the (TBC)2 is developed. It is shown that for small block lengths this H matrix achieves comparable performance. For larger block sizes the H matrix representation of the (TBC)2 encoder is found non-optimal for SPA decoding and the performance of the code is degraded.
Advisors/Committee Members: Dill, Jeffrey.
Subjects: Electrical engineering
Keywords: LDPC codes; Turbo Codes; TBC encoder; SPA; H matrix; parity check matrix; Parallel concatenated Encoder; Turbo SPA
More Like This
7.
Bien-aise, Hemsley.
Adaptive Shared Cache Migration Policy.
Degree: MS, Electrical Engineering (Engineering and Technology), 2010, Ohio University
► The expensive off-chip memory accesses combined with growing on-chip communication delays have…
(more)
▼ The expensive off-chip memory accesses combined with growing on-chip communication delays have called for a reconfigurable last level cache (LLC) to avoid caches from becoming a performance bottleneck in current multicores. The first improvement considered was replicating data close to the processor in a private LLC that would facilitate fast local access while reducing the overall cache capacity and further increasing off-chip memory accesses. On the other hand, a shared LLC increases the overall cache capacity and minimize off- chip misses, but incur higher access latencies by traversing on-chip links to reach distant LLC banks. Similar to replication as in private LLC, cache migration is a promising solution for shared caches that aim to retain more blocks on-chip for faster access without reducing cache capacity. Previous migration schemes do not acknowledge application demand and usage and are very restrictive on the placement of the evicted cache block. This thesis proposes an adaptive shared cache migration policy that optimizes the placement of the most recently used (MRU) cache blocks within the local LLC cache slice (internal migration) or remote LLC cache slice (external migration) with the goal of maximizing the capacity of LLC cache. Full system simulation on 16 core architecture shows that the proposed adaptive migration policy achieves 12-45% improvement in execution time for the majority of SPLASH-2 applications over the baseline shared cache organization while incurring less than 1.4% area overhead.
Advisors/Committee Members: Kodi, Avinash.
Subjects: Electrical engineering
Keywords: L2 cache; CMP; chip multiprocessor; shared; migration; tiled; NUCA
More Like This
8.
Bihl, Trevor Joseph.
State Variable System Identification through Frequency Domain Techniques.
Degree: MS, Electrical Engineering (Engineering and Technology), 2011, Ohio University
► The thesis develops, tests and implements a hybrid frequency domain and state…
(more)
▼ The thesis develops, tests and implements a hybrid frequency domain and state space system identification method. A frequency domain least squares system identification algorithm, along with a coherence function technique for eliminating noisy data is used to sequentially develop discrete single-input, multiple-output (SIMO)transfer function models between each input and the outputs. From the transfer function models, difference equations are obtained. Using the difference equations, discrete impulse responses between each input and each output are computed. These impulse responses are then processed by a state space system identification technique to create a minimum order state space multiple-input, multiple-output (MIMO) model. This process is illustrated with a MIMO example and with data from a laboratory facility called Flexlab.
Advisors/Committee Members: Mitchell, Jerrel.
Subjects: Electrical Engineering
Keywords: system identification; system-ID for control-system design; TFDC; ERA; Eigensystem Realization Algorithm; Transfer Function Determination Code
More Like This
10.
Bruckner, Dean C.
On the Treatment of Noise and Conspiring Bias in Dual-Frequency Differential Global Navigation Satellite Systems.
Degree: PhD, Electrical Engineering (Engineering and Technology), 2010, Ohio University
► Four primary contributions are made to the treatment of noise and conspiring…
(more)
▼ Four primary contributions are made to the treatment of noise and conspiring bias for dual frequency differential Global Satellite Navigation Systems (GNSSs). These contributions enhance accuracy and protection levels for aircraft precision approach and landing operations and similar applications.A statistical characterization is presented of Global Positioning System (GPS) user range error as an uncorrelated, normally distributed random variable with non-zero mean over the length of the aircraft precision approach operation. This leads directly to modeling GPS error in the position domain as multivariate normal with non-zero mean. Based on this model, a vertical composite protection level VPLc and a horizontal composite protection level HPLc are each implemented as univariate normal distributions with non-zero means. A method is presented by which exact values – that is, values accurate to a user-defined error tolerance and consistent with statistical assumptions – of VPLc and HPLc are obtained, and by which computationally efficient approximations may be evaluated. A statistical quadratic form under the multivariate normal distribution is then used to derive a new class of protection levels based on the probability enclosed within a radius defined in two or more dimensions. A central chi-square representation of this quadratic form is also presented, and is incorporated into a six-step computational procedure for the two-dimensional composite radial protection level RPLc. This procedure is extended to the composite spherical protection level (SPLc) and the ellipsoidal protection level (EPLc). Two additional algorithms are presented for dual-frequency differential Global Positioning System (GPS) use. Performance improvements are achieved first through the exchange of pseudorange noise and multipath for reducible biases using a modified Code Noise and Multipath (CNMP) algorithm applied both to reference station and aircraft ranging measurements. In this algorithm, the second frequency is used only to correct the code-minus-carrier (CMC) observable; other ionosphere errors are removed in differential processing. The corrected pseudorange measurements are then combined using a single-frequency carrier phase position domain smoothing (CPDS) algorithm. Composite vertical and horizontal protection levels for the H0 hypothesis are calculated. The algorithms are implemented in a processing architecture suitable for short-baseline differential operations and termed Dual-Frequency Differential 1 (DFD1). They are then tested on recorded flight test data that includes six aircraft precision approaches. Performance is compared to the LAAS single-frequency architecture. Results over the entire flight data set show an improvement in vertical navigation system accuracy from 0.80 m to 0.32 m (95%), and in horizontal accuracy from 0.41 m to 0.33 m (95%). Mean reductions of the vertical and horizontal protection levels by 60% and 57%, respectively, are observed. Similarly, dramatic improvement is seen in all measures for the six 150-s approaches within this flight, including reduction in 95% error from 0.56 m to 0.26 m vertically and from 0.28 m to 0.14 m horizontally. These all demonstrate the effectiveness of the composite protection levels and the CNMP and CPDS algorithms within the DFD1 architecture. This architecture uses C/A code on L1 and carrier phase measurements differenced over time on L1 and L2, but does not resolve integer ambiguities. Nonetheless, it achieves the same level of |μ| + 2σ navigation system error (NSE) performance in these flight tests as in all published studies of similar class systems known to the author that employ differential kinematic carrier phase architectures between ground and air and require ambiguity resolution.
Advisors/Committee Members: van Graas, Frank.
Subjects: Electrical engineering; Remote sensing; Systems design; Transportation
Keywords: GPS; GNSS; differential GPS; LAAS; protection level; conspiring bias; dual frequency; VPL; HPL; SPL; EPL; RPL; CNMP; composite protection level; vertical protection level; horizontal protection level; ellipsoidal protection level; code minus carrier
More Like This
11.
Chandrasekaran, Arvind.
Intra-Vehicle Channel Characterization in the 5 GHz Band.
Degree: MS, Electrical Engineering (Engineering and Technology), 2011, Ohio University
► This thesis presents intra-vehicular channel characterization results in the 5 GHz band,…
(more)
▼ This thesis presents intra-vehicular channel characterization results in the 5 GHz band, for four general purpose aviation aircraft and two automobiles – a van and a bus. With the enormous growth in the field of wireless networking, and the growing need of people to be connected wirelessly, the scarcity of research results for intra-vehicular wireless channel characteristics in the 5 GHz band motivated this research. Measurements were taken in aircraft within the Ohio University airport hangar and in the automobiles in parking lots around the university. Measurement results for a 50 MHz channel bandwidth were used to estimate channel parameters and to develop channel models that could be used in building reliable communication systems for the intra-vehicular channel. The root-mean square delay spread (RMS-DS) values ranged between 10-50 ns for different intra-vehicle channels, with mean RMS-DS values falling between 16-23 ns for automobiles and between 23-29 ns for airplanes. The standard deviations for the RMS-DS statistics were between 2-11 ns. The RMS-DS values were seen to increase with increase in the size of the vehicles and transmitter-receiver distances.
Advisors/Committee Members: Matolak, David.
Subjects: Electrical Engineering
Keywords: Channel characterization; 5 GHz band; Intra-vehicle; Aircraft; Automobile; Within-vehicle
More Like This
12.
Chen, Chen.
Detection of Ionospheric Spatial Gradients.
Degree: MS, Electrical Engineering (Engineering and Technology), 2010, Ohio University
► Spatial ionospheric gradients cause differences in satellite ranging measurements at different locations.…
(more)
▼ Spatial ionospheric gradients cause differences in satellite ranging measurements at different locations. Three algorithms are analyzed in this thesis to estimate the variations in the TEC gradient between two locations. These variations are then used to characterize the size of spatial gradients. Error sources are analyzed for each algorithm and detection thresholds are calculated. Data collected from Ohio University airport and Jordan sites with a 5-km baseline are used to test the feasibility and performance of the three algorithms.
Advisors/Committee Members: van Graas, Frank.
Subjects: Electrical engineering
Keywords: ionospheric spatial gradient; TEC gradient; Receiver biases; Ionospheric delay; GPS
More Like This
13.
Cheng, Kai-Jen.
Comparison and Analysis of Stopping Rules for Iterative Decoding of Turbo Codes.
Degree: MS, Electrical Engineering (Engineering and Technology), 2008, Ohio University
► In this thesis, we are going to compare and analyze the existing…
(more)
▼ In this thesis, we are going to compare and analyze the existing soft and hard stopping rules, which can efficiently terminate the turbo decoders, with the optimal situation using the 10 fixed decoding iterations and discuss how to set an appropriate threshold for these stopping rules without affecting the performances of turbo codes. Thehard stopping rule is simple enough for hardware implementations but not as efficient as the soft stopping rules. Setting the threshold provides the soft criteria have more flexibility to satisfy different applications and a strict threshold makes the soft criteria have better error performances than the hard criterion.
Advisors/Committee Members: Dill, Jeffrey C.
Subjects: Electrical engineering
Keywords: Turbo Codes; Convolutional Code; MAP algorithm; Stop criteria
More Like This
14.
Chiguluri, Praneeth.
Quasi-steady-state Photoluminescence Lifetime Imaging of p- and n-type Multicrystalline Silicon Wafers.
Degree: MS, Electrical Engineering (Engineering and Technology), 2011, Ohio University
► In a silicon solar cell, there are many factors that influence the…
(more)
▼ In a silicon solar cell, there are many factors that influence the efficiency of the cell. Minority-carrier lifetime is the fundamental factor that directly relates to defect and impurity based recombination in silicon affecting the overall quality of the photovoltaic devices. Estimation of minority carrier lifetimes at every stage of the solar cell production without any electrical contacts or device structure is very useful for process development and quality control. The photoluminescence carrier lifetime characterization tool can be applied at different processing stages of solar cell device. The advantages of photoluminescence carrier lifetime imaging tool are fastness and absolute lifetime values are obtained from this method. Unlike, the industry standard characterization tools like Sinton’s lifetime tester and Semilab’s microwave-photoconductive decay method, the photoluminescence lifetimes are absolutely trap free values even at very low injection levels. In this thesis, we demonstrated the applicability of the calibration method developed to solar-grade (SoG) p-type and n-type multicrystalline silicon wafers which have plasma-enhanced chemical vapor deposited (PECVD) silicon nitride (SiN) passivation layers on both sides of the wafer. We have also demonstrated that photoluminescence lifetime imaging technique is a fast, absolute and trap free carrier lifetime characterization method. Also, the obtained results are compared with industry standard carrier lifetime tools like Sinton’s lifetime tester and Semilab’s microwavephotoconductive decay method. Furthermore, we suggest some improvements in the calibration method and we also discuss the applicability of this characterization method to other silicon morphologies. The thesis also presents the preliminary work on the light-induced carrier lifetime degradation in Al doped multicrystalline silicon wafers. The lifetime degradation upon illumination of light is seen in Al doped multicrystalline p-Si wafers. After annealing the wafers at 200°C for 1 hour the initial lifetime is recovered. Furthermore, Fourier Transform Infrared (FTIR) spectroscopy is performed to check the oxygen content present in the wafers. Based on these results we conclude that the degradation effect is due to interstitial oxygen present in the wafers. The work was carried out at Energy research Center of Netherlands under the supervision of Dr. Gianluca Coletti.
Advisors/Committee Members: Jadwisienczak, Wojciech.
Subjects: Electrical Engineering; Energy; Optics
Keywords: silicon solar wafers, photoluminescence, carrier lifetime imaging, photoconductance
More Like This
15.
Chowdhari, Vikram.
Performance of a Low Rate Duo - Binary Turbo Decoder With Genetic Optimization.
Degree: MS, Electrical Engineering (Engineering and Technology), 2009, Ohio University
► Turbo Code is a method of error correction coding, whose performance is…
(more)
▼ Turbo Code is a method of error correction coding, whose performance is veryclose to the Shannon limit. It has a feedback loop which decodes the data more efficiently. For several years, improvement in the performance of the system using turbo codes is obtained. In this thesis various non-linear and stochastic optimizing techniques are tested to improve the codeword error rate, by bringing it close to Shannon limit. A mathematic optimization called Genetic Algorithm is used and good performance is obtained.
Advisors/Committee Members: Dill, Jeffrey.
Subjects: Electrical engineering
Keywords: turbo codes; genetic algorithm; duo binary turbo codes; error correction codes
More Like This
16.
Clark, Kendal W.
STM Study of Molecular and Biomolecular Electronic Systems.
Degree: PhD, Electrical Engineering (Engineering and Technology), 2010, Ohio University
► This dissertation work is focused on the study of two molecular electronic…
(more)
▼ This dissertation work is focused on the study of two molecular electronic systems: (BETS)2GaCl4 and a Nanoscale Protein Molecular Wire. The detailed structural and electronic study of these systems was carried out using a custom built Ultra-High Vacuum Low Temperature Scanning Tunneling Microscope (UHV-LT-STM). The STM is capable of studying these systems with a spatial and energy resolution that has never been achieved before. λ-(BETS)2GaCl4 is a charge transfer superconductor in bulk crystals. Using a unique deposition procedure, a single sheet of the superconductor was formed on a Ag(111) metal surface. Molecular resolution imaging of the well ordered molecular layer revealed the exact arrangement of the molecules on the surface. The superconductivity of the layer was confirmed by scanning tunneling spectroscopy and spectroscopic mapping. The superconducting signal remained down to a chain of only four molecular pairs, which was only 3.5 nm long. The structure of the nanoscale protein molecular wire is revealed by high resolution STM imaging. Single proteins are imaged and individual amino acid side chains are resolved. Electronic and vibrational properties are explored using the spectroscopic capability of the STM. The STM images, in combination with high resolution vibrational spectroscopy, allow for the first direct sequencing of individual proteins. These two systems have unique properties that could be used as key components in the new class of Nano/Bio electronics. By developing a better understanding of the properties of these systems at the nanoscale, this PhD study answers questions about the electronic and structural properties of these systems and points towards their future electronic and bio-medical applications.
Advisors/Committee Members: Kaya, Savas.
Subjects: Electrical engineering; Physics
Keywords: Scanning Tunneling Microscope; STM; Nanotechnology; Molecular Superconductor; Protein; Scanning Tunneling Spectroscopy; Molecular Electronics
More Like This
17.
Cohenour, John C.
Global Positioning System Clock and Orbit Statistics and Precise Point Positioning.
Degree: PhD, Electrical Engineering (Engineering and Technology), 2009, Ohio University
► The orbit and clock errors of GPS satellites are examined culminating in…
(more)
▼ The orbit and clock errors of GPS satellites are examined culminating in error distributions and Gaussian overbounds. The Precise Orbit and Clock (POC) data are then used to produce a Precise Point Position (PPP) solution with a maximum vertical error of ±1 meter. Flight test data are processed using the Single Difference Residual (SDR) method to detect and correct cycle-slips. The corrected carrier phase measurements are then used in PPP to determine the user's position. The results are compared with truth data to characterize the PPP solution accuracy performance.POC data from the International GNSS Service (IGS), National Geospatial-intelligence Agency (NGA), and the Center for Orbit Determination in Europe (CODE), are used as the truth reference and compared to the broadcast GPS ephemerides obtained from the Scripps Orbit and Permanent Array Center (SOPAC). The error is then analyzed over the three year period from June 2005, through June 2008. Two hundred forty-seven events in which the error in orbit or clock exceed 25 m are identified. These events are classified as outliers. The outliers are compared against data from IGS station receivers to determine if the event is observable. Observable events are reclassified as anomalies. Thirteen anomalies are identified and tabularized to enable future researchers to test anomaly detection mechanisms against historical events. The table of anomalies represents an original contribution to existing research in this field. The anomalies are removed from the data. The remaining data are analyzed statistically. Seven error metrics are analyzed. Error distribution and a Gaussian overbound are provided by error metric and satellite block type. The error data are then differenced over time. Three Operational Scenarios (OSs) are analyzed. OS1 is the normal operating procedure in which each ephemeris is used as soon as it is received. OS2 uses only one ephemeris. In OS2 the ephemeris is used from the time it is received until it expires, or until the satellite health is set to unhealthy. OS3 uses each ephemeris as it becomes available but the transitions are made continuous. OS2 and OS3 require that the duration of the anomaly be extended. These data are tabularized separately. Distributions for the error data and Gaussian overbounds are provided. Distributions are provided by error metric, block type, and time interval. Flight test data are preprocessed using the SDR method to detect and remove cycle-slips before performing a PPP solution. The SDR method requires five satellites and can detect a cycle-slip on one satellite. This is done by comparing the precise average velocity residual for each solution with one satellite removed. Removal of a cycle-slipped satellite removes the clock velocity error from the solution and allows the offending satellite to be identified. A PPP solution is generated for the SDR processed data. The PPP solution provides errors of less than 1 m maximum vertical. Maximum horizontal errors are less than 0.35 m two-dimensional.
Advisors/Committee Members: van Graas, Frank.
Subjects: Electrical engineering
Keywords: GPS; PPP; Precise Point Positioning; GPS Orbit; GPS Clock; Kalman Filter
More Like This
19.
Davis, Nidhin.
Comparison of Ray Tracing and Measurement Results for 5GHz Band Wireless Channels.
Degree: MS, Electrical Engineering (Engineering and Technology), 2009, Ohio University
► This thesis describes a comparison of ray tracing results obtained using a…
(more)
▼ This thesis describes a comparison of ray tracing results obtained using a commercial ray tracing software tool (Wireless Insite) to measured channel impulse response results for 5 GHz wireless band channels. Four sets of measurements were taken at an open parking lot by varying the transmitter and receiver positions with respect to the building. The channel impulse response, mean excess delay and root mean square delay spread were obtained from the measurements. We approximated the same environment in the software and obtained the channel impulse response and root-mean-square (RMS) delay spread (DS). The ray tracing and measured power delay profiles (PDPs) were first compared qualitatively, then the measured and ray tracing RMS-DS values were compared quantitatively. An accuracy analysis was done by varying the objects used in the ray tracing program and assessing the effects of this on results. A perturbation analysis was also conducted by varying by small amounts the transmitter distance, receiver distance, the number of reflections, and combinations of these to assess potential errors in our measured distance and hypothesized numbers of significant reflections. The results showed that the PDPs obtained using ray tracing are comparable to the measured results qualitatively and the perturbation analysis helped in modeling the inaccuracies involved during the measurements.
Advisors/Committee Members: Matolak, Dr. David.
Subjects: Electrical engineering
Keywords: Ray Tracing; Wireless communications; Wireless Insite; Accuracy analysis; 5GHz
More Like This
20.
DeLashmutt, Timothy E.
Modeling of a Proton Exchange Membrane Fuel Cell Stack.
Degree: MS, Electrical Engineering (Engineering and Technology), 2008, Ohio University
► This thesis presents the modification of Pukrushpan's fuel cell model to include…
(more)
▼ This thesis presents the modification of Pukrushpan's fuel cell model to include cathode flooding with water, water management by cathode outlet control valve, and hydrogen control by hydrogen control valve. The control objectives discussed in this document were created to meet the design requirements of maximizing the net power and preventing damage to the fuel cell. The differential equations that describe the model are very nonlinear and highly coupled. In order to facilitate controller design improved model is reduced by the standard singular perturbation method to eliminate fast-mode state variables by simplifying them to algebraic equations. These algebraic equations are used to create a simplified model that can describe the dominant slow-mode state with adequate accuracy for controller design.
Advisors/Committee Members: Zhu, Jianchao.
Subjects: Electrical engineering; Engineering
Keywords: Fuel Cell; PEMFC; singular perturbation method; singular perturbation; control; modeling; Matlab; Simulink
More Like This
21.
Dickman, Jeff.
Single Platform Relative Positioning for Sensor Stabilization.
Degree: PhD, Electrical Engineering (Engineering and Technology), 2008, Ohio University
► Intelligence, Surveillance, and Reconnaissance (ISR) sensors such as radio detecting and ranging,…
(more)
▼ Intelligence, Surveillance, and Reconnaissance (ISR) sensors such as radio detecting and ranging, laser detecting and ranging, electro-optic / infra-red, and other remote sensing activities are becoming increasingly dependent on their position and orientation in time and space. The higher dynamics of flight and the increased sensor requirements have led to the need for sensor stabilization by direct motion measurement. A stabilization system based on the Global Positioning System (GPS) can provide good performance, but high frequency ISR sensor pointing applications have led to the need for additional measurement bandwidth, accuracy, and robustness. Two significant issues will be addressed in this dissertation to improve the stabilization system robustness and accuracy at the mm level: GPS Carrier Phase measurement noise using inertial measurements and carrier phase multipath. Higher bandwidth requirements (i.e., hundreds of Hz) will be addressed with the incorporation of a high-rate inertial measurement unit. All concepts developed in this dissertation will be illustrated using real sensor data from either static aircraft tests on the tarmac or dynamic flight tests. The work to be described in this document will expand the state-of-the-art in the area of navigation sensor noise reduction while preserving high measurement bandwidth. Coupling GPS and inertial measurements has demonstrated the required improvements in similar applications, but an approach was sought which was tailored for the stabilization application. This dissertation will examine both optimal and non-optimal coupling of navigation sensors to form optimized high-accuracy single-platform relative position measurements with the intent to coherently stabilize ISR sensors. This dissertation also examines GPS carrier phase multipath as an error contributor in the ground calibration of the ISR sensor antenna baseline. Several indicators will be examined as a means to exclude satellites from the calibration data. Also, the narrowlane measurement combination technique will be used as a means to mitigate the remaining carrier phase multipath in the baseline solution. The contributions of this work include a framework for the single-platform stabilization problem, sensor integration and alignment techniques for single-platform baseline stabilization, an inertial synthesized baseline technique for smoothing noise in the GPS measurements, multipath considerations pertaining to the ground-calibration of sensors, and a demonstration of the utility of the narrow-lane linear combination for dual frequency GPS noise and multipath reduction.
Advisors/Committee Members: Bartone, Chris G.
Subjects: Electrical engineering; Engineering
Keywords: GPS; INS; multipath; sensor stabilization; high accuracy relative positioning; navigation; carrier phase
More Like This
22.
Dill, Evan T.
Integration of 3D and 2D Imaging Data for Assured Navigation in Unknown Environments.
Degree: MS, Electrical Engineering (Engineering and Technology), 2011, Ohio University
► As technology advances in the area of mobile vehicles, the need for…
(more)
▼ As technology advances in the area of mobile vehicles, the need for precise reliable navigation increases with it. Whether the vehicle is an unmanned aerial vehicle (UAV), a manned aerial vehicle (MAV), or an intelligent ground vehicle (IGV), there is a constant need for precise navigation capabilities. This need spurred the invention and development of many navigation systems including the most useful system to date, the Global Positioning System (GPS). GPS is a powerful tool that can reliably give meter level accuracy on a world-wide scale. With this capability, GPS is the answer to a significant number of navigation problems, but it is not the answer to them all. Since GPS relies on exterior signals from orbiting satellites, tasks such as underground navigation and navigation in dense foliage can be difficult due to signal strength attenuation as it passes through these media. GPS is also very susceptible to multipath at the receiver. If the receiver is operating in a building or in a heavy urban environment, the multipath created can degrade the received signal to the point of losing its true capabilities. Lastly, GPS capabilities are ideal for military applications. However, any system that uses exterior signals for military applications must deal with the possibility of interference, jamming, or even an attack on the system in a wartime scenario. Although, the list of scenarios in which GPS is not a viable answer is small, it is important that those scenarios be addressed. One viable possibility is developing a new system that complements GPS by having functionality in scenarios in which GPS is a poor option or not an option at all. This thesis describes and discusses one such possibility that could complement GPS. The proposed system is a self contained system that would use multiple sensors and the environment around them for navigation. This method would integrate three-dimensional (3D) point cloud data, two-dimensional (2D) gray-level (intensity) data, 2D digital image data, and data from an Inertial Measurement Unit (IMU). Using the 2D and 3D image frames, key features can be extracted from the surroundings such as planar surfaces, lines, and corners. Positions of the features can be calculated with respect to the sensors observing them. With these features, consecutive observations in the 3D and 2D image frames can be used to compute and estimate position and orientation change of the sensors. The use of 3D image features for positioning suffers from limited feature observability, which results in deteriorated position accuracies. Also, the 2D imagery suffers from an unknown depth when estimating the position from consecutive image frames. It is expected that the integration of these two data sets will alleviate the problems with the individual methods, resulting in a position and attitude determination method with a high level of assurance. An IMU will be used to set up the tracking gates necessary to perform feature association in consecutive frames. Finally, the position and orientation change estimates can be used to correct for the IMU drift errors using an Extended Kalman Filter (EKF), and output inertial data that drifts at a significantly slower rate than that of the IMU without this correction.
Advisors/Committee Members: Uijt de Haag, Maarten.
Subjects: Electrical Engineering
Keywords: feature extraction; Kalman filtering; EKF; inertial navigation; vision-aided navigation; 2D imaging; 3D imaging
More Like This
23.
DiTomaso, Dominic F.
Improving Energy Efficiency of Network-on-Chips Using Emerging Wireless Technology and Router Optimizations.
Degree: MS, Electrical Engineering (Engineering and Technology), 2012, Ohio University
► As silicon technology scales down to the sub-nanometer region, chip designs are…
(more)
▼ As silicon technology scales down to the sub-nanometer region, chip designs are moving toward chip multiprocessors (CMPs), integrating hundreds and even thousands of smaller cores on a single chip. As such, the design and implementation of the underlying communication fabric is becoming a critical challenge. Traditional bus-based networks have problems with scalability and latency. Network-on-Chip (NoC) architectures overcome these problems by using packet switched networks that connect cores in topologies such as meshes or tori. However, traditional NoC topologies use metallic interconnects which cause high latency and power consumption as technology nodes scale down in size. Additionally, the routers in packet switched networks have power hungry buffers and large crossbars. A potential solution to the interconnect problems is wireless links. Wireless interconnects can provide low power and low latency communication between cores. In this thesis, a wireless architecture called iWISE is proposed, which is a scalable, wireless/wired hybrid network that reduces power and improves throughput and latency over other wired and wireless networks. To overcome the router buffer and crossbar problems, a CTorus topology is proposed in a separate network which uses low power channel buffers and smaller, split crossbars to improve overall network performance and power.
Advisors/Committee Members: Kodi, Avinash.
Subjects: Computer Engineering
Keywords: Network-on-Chip; Wireless Interconnects; Channel Buffers; Crossbars; Power-efficient; NoC; CMP; Router Optimizations; Energy efficient
More Like This
24.
Duan, Pengfei.
Automatic Dependent Surveillance-Broadcast (ADS-B) Space-Oriented Message Set Design.
Degree: MS, Electrical Engineering (Engineering and Technology), 2011, Ohio University
► Automatic Dependent Surveillance-Broadcast (ADS-B) is introduced to aid the commercial space flight…
(more)
▼ Automatic Dependent Surveillance-Broadcast (ADS-B) is introduced to aid the commercial space flight operations, accommodate space vehicles transitioning through the National Airspace System (NAS), seamlessly integrate the future space transportation system with the air transportation system, and minimize space vehicles impacts and potential hazards on the NAS. A feasibility study is conducted to show ADS-B is capable of supporting space flight operations by examining ADS-B-related system issues and technical issues individually. A potential ADS-B space-oriented message set is proposed to be exclusively transmitted from space vehicles to other traffic and air traffic controllers. A simulation is performed to test the functionality of the message set, and sensitivity of three ADS-B system parameters, which are message update rate, data latency, and state vector accuracy.
Advisors/Committee Members: Rankin, James.
Subjects: Aerospace Engineering; Electrical Engineering
Keywords: ADS-B; NextGen; Space Flight Operations; Universal Access Transceiver (UAT); Collision Avoidance; Surveillance
More Like This
25.
Fisher, Joseph E.
Telescope Automation Project.
Degree: MS, Electrical Engineering (Engineering and Technology), 2001, Ohio University
Telescope Automation Project
Advisors/Committee Members: Irwin, R. Dennis.
Subjects: Electrical engineering
Keywords: Telescope Automation
More Like This
26.
Frey, Nathan J.
Hierarchical Latent Networks for Image and Language Correlation.
Degree: MS, Electrical Engineering (Engineering and Technology), 2011, Ohio University
► Purely statistical methods for modeling relationships between languages or images suffer from…
(more)
▼ Purely statistical methods for modeling relationships between languages or images suffer from over-connectivity and inaccurate assumptions about the independence of inputs. This thesis aims to design a system that will model statistically dependent inputs, create a sparse hierarchy to classify inputs at different levels of abstraction and use causal relationships to deliver an output based on prior training. This parallel architecture is implemented sequentially through a Hierarchical Latent Class Engine (HLCE) grows only as required in conductivity, classifiers and layers of hierarchy. In addition, grouping of inputs and outputs provides for increased comprehension and prediction engines help provide correct outputs to novel inputs. The HLCE unitizes Levenshtein distance sequence comparison, logistic regression based set matching, SURF image keypoint detection and cosine similarity prediction detection. Though the concept of the system can be applied to any types of inputs and outputs special emphasis was placed on language and images. The software implementation of this system is capable of producing correct natural language descriptions it has never said before of images it has never seen before. It can also produce correct translations of phrases it has never been trained with.
Advisors/Committee Members: Starzyk, Janusz.
Subjects: Computer Science; Electrical Engineering
Keywords: Computer Vision; Natural Language Processing; Bag of Words; Describing Images
More Like This
27.
Gorthy, Anantha Surya Raghu.
A Study on the Effects of Decoder Quantization of Digital Video Broadcasting - Return Channel over Satellite (DVB-RCS) Turbo Codes.
Degree: MS, Electrical Engineering (Engineering and Technology), 2008, Ohio University
► Digital Video Broadcasting - Return Channel over Satellite (DVB-RCS) Turbo Codes have…
(more)
▼ Digital Video Broadcasting - Return Channel over Satellite (DVB-RCS) Turbo Codes have become increasingly popular because of their ability to provide an uplink and downlink on the same path. However, the hardware implementation of these codes remains a challenge to the engineers and designers. This research focuses on the implications of quantizing a decoder's input to achieve a significant improvement in the hardware implementation of the decoding architecture. The performance issues related to the quantization have been studied in detail. An approach to achieving performances very close to the floating point methodologies has been presented in the form of an algorithm. Results show that by sacrificing very little performance, cost effective and optimal hardware designs can be obtained.
Advisors/Committee Members: Dill, Jeffrey C.
Subjects: Electrical engineering
Keywords: Turbo Codes; DVB-RCS Codes; Digital Communications; Quantization
More Like This
28.
Hassana Ramesh, Rakesh Kashyap.
Transform Domain Acquisition of Spread Spectrum Signals in a Low Signal to Noise Ratio Environment.
Degree: MS, Electrical Engineering (Engineering and Technology), 2010, Ohio University
► Signal acquisition in direct sequence spread spectrum (DSSS) communication systems determines the…
(more)
▼ Signal acquisition in direct sequence spread spectrum (DSSS) communication systems determines the efficiency of the receiver. Problems like Doppler shift and timing uncertainty further reduces the performance of the acquisition process. This research presents a performance based comparative study of transform domain and time domain signal acquisition algorithms on asynchronous DSSS signals in an additive white Gaussian noise (AWGN) channel with Doppler uncertainty. The lowest possible signal to noise ratio (SNR) that can be detected perfectly for a 128 chip preamble is analyzed.
Advisors/Committee Members: Dill, Jeffrey.
Subjects: Electrical engineering
Keywords: Transform Domain Acquisition; DSSS; Doppler Estimation; Preamble Acquisition; Timing Estimation
More Like This
29.
Huang, Weizheng.
Investigation on Digital Fountain Codes over Erasure Channels and Additive White Gaussian Noise Channels.
Degree: PhD, Electrical Engineering (Engineering and Technology), 2012, Ohio University
► As newly invented packet erasure codes, digital fountain codes (LT codes and…
(more)
▼ As newly invented packet erasure codes, digital fountain codes (LT codes and Raptor codes) under iterative message passing decoding can work very efficiently in computer networks for large scale data distribution (e.g., greater than 64000 bits) without knowledge of the states of individual lossy channels, regardless of the propagation modes. Some researchers have moved further and found that fountain codes can achieve near capacity performance over AWGN channels. However, little literature on the research of a fountain code’s decoding overhead had been obtained, especially for short and moderate-length data (e.g., smaller than 10000 bits). We are interested in the overheads of fountain codes of different kinds or designs because a harsh communication condition can hurt some decoding schemes by limiting the number of received encoded symbols. Moreover, we have only found in literature studies of Raptor codes whose precodes are rate 0.98 left-regular, right-Poisson LDPC codes, but performance with other types of pre-codes is unknown. In this dissertation, we review conventional fountain codes and describe two system models for packet erasure fountain codes and bit error correcting fountain codes under message passing decoding over binary erasure channels or AWGN channels. We assess Raptor codes with different kinds of pre-codes, introduce maximum likelihood decoding to both LT codes and Raptor codes, and propose a hybrid message passing and fast maximum likelihood decoding algorithm for LT codes. Our simulation results show that error rate and overhead depends on both decoding algorithm and pre-code characteristics. In general, maximum likelihood decoding consumes much less overhead than message passing decoding. Our hybrid algorithm can realize very low overhead with short-length LT codes but still enable fast decoding. LT codes can decrease the fraction of overhead as data length grows but Raptor codes may not. A higher rate pre-code can accomplish better performance of Raptor codes than a lower rate pre-code, and the structure of the pre-code may not matter.
Advisors/Committee Members: Dill, Jeffrey.
Subjects: Computer Engineering; Electrical Engineering; Engineering
Keywords: fountain code; LT code; Raptor code; message passing; maximum likelihood; LDPC code
More Like This
30.
Huang, Yiming.
Phoneme Recognition Using Neural Network and Sequence Learning Model.
Degree: MS, Electrical Engineering (Engineering and Technology), 2009, Ohio University
► The purpose of this thesis is to describe a biologically motivated approach…
(more)
▼ The purpose of this thesis is to describe a biologically motivated approach for phoneme recognition by using a self-organized neural network and sequence learning algorithm. Phoneme recognition in continuous speech is a tough task with a low accuracy rate. By using the sequence learning algorithm to add sequential information of individual phonemes, recognition performance can be improved.This thesis includes three parts. A self-organized neural network is the first stage, which classifies the input sound waves into forty two different phoneme categories. The 42 output neurons of the neural network are sent to the Sequence Learning block which is composed of Long Term Memory cells. Finally each LTM cell sends a unique feedback strength signal to each output of the neural network to predict the next phoneme, hence, to improve the phoneme recognition based on the sequential information.
Advisors/Committee Members: Starzyk, Janusz.
Subjects: Artificial intelligence; Design; Electrical engineering; Engineering
Keywords: Phoneme Recognition; Neural Network; Long-Term Memory; Sequence Learning
More Like This
[1] [2] [3]
