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Articles 1 - 30 of 66
Full-Text Articles in Engineering
Pulsed Dielectric Breakdown And Permittivity Characterization Of Composite Solid Insulators In Pulsed Power Systems, Shawn T. Scoggin
Pulsed Dielectric Breakdown And Permittivity Characterization Of Composite Solid Insulators In Pulsed Power Systems, Shawn T. Scoggin
Electrical Engineering Dissertations
In high voltage pulsed power systems, liquids and gases are often used as insulating materials because they offer high breakdown strengths, conform around complex geometries, and are self-healing, but they can introduce significant engineering challenges and restrictions when it comes to implementing them. Solid dielectrics can be desirable for improving the maintenance requirements, shelf life, and power/energy density metrics associated with insulating high voltage pulsed power systems, however they possess design challenges of their own. Solid dielectrics are not self-healing and can be difficult to manufacture, especially around complex geometries. Epoxy dielectrics are of high interest because of their naturally …
On The Permittivity Of Xt-Cf20, Aaron Harmon, Wei Zhang, Victor Khilkevich
On The Permittivity Of Xt-Cf20, Aaron Harmon, Wei Zhang, Victor Khilkevich
Electrical and Computer Engineering Faculty Research & Creative Works
In This Work, the Permittivity of a 3D-Printed Carbon Fiber-Loaded Anisotropic Material, XT-CF20, is Examined Further. the Microstructure of XT-CF20 is First Examined Via Optical Imaging and is Shown to Be Composed of Inclusions that Are Aligned with the Print Direction of the Sample. the Permittivity Tensor for the Aligned Microstructure is Then Measured using a Capacitive Measurement Technique and Simulations Are Provided to Demonstrate the Validity of This Measurement Method. the Simulated Permittivity Values for XT-CF20 Samples with Varying Infill Structures Are Then Presented and Compared to the Measured Permittivity Values of Said Samples. an Error of Less Than …
Design And Operation Of A Microwave Flow Cytometer For Single Cell Detection And Identification, Jeffrey A. Osterberg
Design And Operation Of A Microwave Flow Cytometer For Single Cell Detection And Identification, Jeffrey A. Osterberg
All Dissertations
Microwave dielectric sensing has become a popular technique in biological cell sensing for its potential in online, label-free, and real-time sensing. At microwave frequencies probing signals are sensitive to intracellular properties since they are able to penetrate cell membranes, making microwave flow cytometry a promising technology for label-free biosensing. In this dissertation a microwave flow cytometer is designed and used to measure single biological cells and micro particles. A radio frequency (RF)/microwave interferometer serves as the measurement system for its high sensitivity and tunability and we show that a two-stage interferometer can achieve up to 20 times higher sensitivity than …
Characterization Of Anisotropic Materials Using Scattered Field Measurements, Hirsch M. Chizever
Characterization Of Anisotropic Materials Using Scattered Field Measurements, Hirsch M. Chizever
Theses and Dissertations
This research uses monostatic far-zone scattered field measurements to estimate the permittivity of biaxial materials at X-Band. Utilizing Radar Cross Section (RCS) measurement techniques, this effort examines the efficacy of whole-sample TEM illumination in the estimation of anisotropic permittivity, in contrast with traditional subsample illumination methods. The research examines the impact that dielectric supports have on measurement error and uncertainty in permittivity estimates. Following an incremental approach, the research first demonstrates successful estimation of permittivity for isotropic spheres followed by a Teflon isotropic cube. Finally, the method is applied to uniaxial and biaxial cubes whose anisotropic permittivity is validated through …
Electromagnetic Wave Propagation For Industry And Biomedical Applications, Fred Lacy
Electromagnetic Wave Propagation For Industry And Biomedical Applications, Fred Lacy
Faculty Publications
Superconductors have a wide array of applications, such as medical imaging, supercomputing, and electric power transmission, but superconducting materials only operate at very cold temperatures. Thus, the quest to engineer room temperature superconductors is currently a hot topic of research. To accomplish this mission, it is important to have a complete understanding of the material properties that are being used to create these superconductors. Understanding the atomic and electromagnetic properties of the prospective materials will provide tremendous insight into the best choice for the materials. Therefore, a theoretical model that incorporates electromagnetic field theory and quantum mechanics principles is utilized …
International Journal Of Electrical And Computer Engineering, Fred Lacy
International Journal Of Electrical And Computer Engineering, Fred Lacy
Faculty Publications
A superconductor has the ability to conduct electricity perfectly and exclude magnetic fields from its interior. In order to understand electromagnetic characteristics of superconductors, their material properties need to be examined. To facilitate this understanding, a theoretical model based on concepts of electromagnetics is presented to explain the electrical and magnetic properties of superconductors. The permittivity response is the key aspect of the model and it describes the electrical resistance response and why it vanishes at the material’s critical temperature. The model also explains the behavior of magnetic fields and why they cannot exist inside superconducting materials. The theoretical concepts …
A Survey On Subsurface Signal Propagation, Usman Raza, Abdul Salam
A Survey On Subsurface Signal Propagation, Usman Raza, Abdul Salam
Faculty Publications
Wireless Underground Communication (WUC) is an emerging field that is being developed continuously. It provides secure mechanism of deploying nodes underground which shields them from any outside temperament or harsh weather conditions. This paper works towards introducing WUC and give a detail overview of WUC. It discusses system architecture of WUC along with the anatomy of the underground sensor motes deployed in WUC systems. It also compares Over-the-Air and Underground and highlights the major differences between the both type of channels. Since, UG communication is an evolving field, this paper also presents the evolution of the field along with the …
Decision Agriculture, Abdul Salam, Usman Raza
Decision Agriculture, Abdul Salam, Usman Raza
Faculty Publications
In this chapter, the latest developments in the field of decision agriculture are discussed. The practice of management zones in digital agriculture is described for efficient and smart faming. Accordingly, the methodology for delineating management zones is presented. Modeling of decision support systems is explained along with discussion of the issues and challenges in this area. Moreover, the precision agriculture technology is also considered. Moreover, the chapter surveys the state of the decision agriculture technologies in the countries such as Bulgaria, Denmark, France, Israel, Malaysia, Pakistan, United Kingdom, Ukraine, and Sweden. Finally, different field factors such as GPS accuracy and …
Electromagnetic Characteristics Of The Soil, Abdul Salam, Usman Raza
Electromagnetic Characteristics Of The Soil, Abdul Salam, Usman Raza
Faculty Publications
The electromagnetic characteristics of the soil are discussed in this chapter. The characteristics of porous bedrock, soil medium, and impacts of rain attenuations are also presented. The models of dielectric soil properties are studied with a rigorous focus on the constitutive parameters of subsurface soil medium. Moreover, the permittivity and wavenumber in soil are explained. In addition, the frequency-dependent dielectric properties such as dispersion in soil, absorption characteristic, and penetration depth versus frequency are reviewed. Furthermore, the effective permittivity of soil–water mixture for through-the soil-propagation mechanism is analyzed thoroughly.
Underground Phased Arrays And Beamforming Applications, Abdul Salam, Usman Raza
Underground Phased Arrays And Beamforming Applications, Abdul Salam, Usman Raza
Faculty Publications
This chapter presents a framework for adaptive beamforming in underground communication. The wireless propagation is thoroughly analyzed to develop a model using the soil moisture as an input parameter to provide feedback mechanism while enhancing the system performance. The working of array element in the soil is analyzed. Moreover, the effect of soil texture and soil moisture on the resonant frequency and return loss is studied in detail. The wave refraction from the soil–air interface highly degrades the performance of the system. Furthermore, to beam steering is done to achieve high gain for lateral component improving the UG communication. The …
Signals In The Soil: Underground Antennas, Abdul Salam, Usman Raza
Signals In The Soil: Underground Antennas, Abdul Salam, Usman Raza
Faculty Publications
Antenna is a major design component of Internet of Underground Things (IOUT) communication system. The use of antenna, in IOUT, differs from traditional communication in that it is buried in the soil. Therefore, one of the main challenges, in IOUT applications, is to establish a reliable communication. To that end, there is a need of designing an underground-specific antenna. Three major factors that can impact the performance of a buried antenna are: (1) effect of high soil permittivity changes the wavelength of EM waves, (2) variations in soil moisture with time affecting the permittivity of the soil, and (3) difference …
Soil Moisture And Permittivity Estimation, Abdul Salam, Usman Raza
Soil Moisture And Permittivity Estimation, Abdul Salam, Usman Raza
Faculty Publications
The soil moisture and permittivity estimation is vital for the success of the variable rate approaches in the field of the decision agriculture. In this chapter, the development of a novel permittivity estimation and soil moisture sensing approach is presented. The empirical setup and experimental methodology for the power delay measurements used in model are introduced. Moreover, the performance analysis is explained that includes the model validation and error analysis. The transfer functions are reported as well for soil moisture and permittivity estimation. Furthermore, the potential applications of the developed approach in different disciplines are also examined.
Current Advances In Internet Of Underground Things, Abdul Salam, Usman Raza
Current Advances In Internet Of Underground Things, Abdul Salam, Usman Raza
Faculty Publications
The latest developments in Internet of Underground Things are covered in this chapter. First, the IOUT Architecture is discussed followed by the explanation of the challenges being faced in this paradigm. Moreover, a comprehensive coverage of the different IOUT components is presented that includes communications, sensing, and system integration with the cloud. An in-depth coverage of the applications of the IOUT in various disciplines is also surveyed. These applications include areas such as decision agriculture, pipeline monitoring, border control, and oil wells.
Signals In The Soil: Subsurface Sensing, Abdul Salam, Usman Raza
Signals In The Soil: Subsurface Sensing, Abdul Salam, Usman Raza
Faculty Publications
In this chapter, novel subsurface soil sensing approaches are presented for monitoring and real-time decision support system applications. The methods, materials, and operational feasibility aspects of soil sensors are explored. The soil sensing techniques covered in this chapter include aerial sensing, in-situ, proximal sensing, and remote sensing. The underlying mechanism used for sensing is also examined as well. The sensor selection and calibration techniques are described in detail. The chapter concludes with discussion of soil sensing challenges.
Autonomous Irrigation Management In Decision Agriculture, Abdul Salam, Usman Raza
Autonomous Irrigation Management In Decision Agriculture, Abdul Salam, Usman Raza
Faculty Publications
In this chapter, the important application of autonomous irrigation management in the field decision agriculture is discussed. The different types of sensor-guided irrigation systems are presented that includes center pivot systems and drip irrigation systems. Their sensing and actuator components are with detailed focus on real-time decision-making and integration to the cloud. This chapter also presents irrigation control systems which takes, as an input, soil moisture and temperature from IOUT and weather data from Internet and communicate with center pivot based irrigation systems. Moreover, the system architecture is explored where development of the nodes including sensing and actuators is presented. …
Variable Rate Applications In Decision Agriculture, Abdul Salam, Usman Raza
Variable Rate Applications In Decision Agriculture, Abdul Salam, Usman Raza
Faculty Publications
In this chapter, the variable rate applications (VRA) are presented for the field of decision agriculture. The characteristics of VRA control systems are described along with control hardware. Different types of VRA systems are discussed (e.g., liquid VRA systems and dry VRA systems). A case study is also explored in this regard. Moreover, recent advances and future trends are also outlined. Accordingly, a sustainable variable-rate irrigation scheduling is studied where different hardware and software component of the cyber-physical system are considered. Finally, chapter is concluded with a novel sensor deployment methodology.
Liquid Metal-Elastomer Soft Composites With Independently Controllable And Highly Tunable Droplet Size And Volume Loading, Ravi Tutika, Steven Kmiec, A. B. M. Tahidul Haque, Steve W. Martin, Michael D. Bartlett
Liquid Metal-Elastomer Soft Composites With Independently Controllable And Highly Tunable Droplet Size And Volume Loading, Ravi Tutika, Steven Kmiec, A. B. M. Tahidul Haque, Steve W. Martin, Michael D. Bartlett
Michael Bartlett
Soft composites are critical for soft and flexible materials in energy harvesting, actuators, and multifunctional devices. One emerging approach to create multifunctional composites is through the incorporation of liquid metal (LM) droplets such as eutectic gallium indium (EGaIn) in highly deformable elastomers. The microstructure of such systems is critical to their performance, however, current materials lack control of particle size at diverse volume loadings. Here, we present a fabrication approach to create liquid metal-elastomer composites with independently controllable and highly tunable droplet size (100 nm ≦ D ≦ 80 μm) and volume loading (0 ≦ φ ≦ 80%). This is …
Electromagnetic Characterization Of Conductor-Backed Media Using Stepped Rectangular Waveguide, Avian Y. Hughes
Electromagnetic Characterization Of Conductor-Backed Media Using Stepped Rectangular Waveguide, Avian Y. Hughes
Theses and Dissertations
A new single stepped-iris waveguide technique is used to nondestructively determine the permittivity and permeability of conductor-backed media. This thesis will demonstrate a proof-of-concept that obtains two independent reflection measurements with a magnetic radar absorbing material (magRAM). Using a two measurement procedure, in which, the first measurement will apply a single rectangular waveguide to a known conductor-backed absorbing material under test (MUT) and the second measurement will insert a stepped-iris in between the single rectangular waveguide and MUT reducing the aperture to retrieve two independent electromagnetic properties (i.e. permittivity and permeability). The theoretical reflection coefficients are obtained using a rigorous …
A Triaxial Applicator For The Measurement Of The Electromagnetic Properties Of Materials, Saranraj Karuppuswami, Edward Rothwell, Premjeet Chahal, Michael J. Havrilla
A Triaxial Applicator For The Measurement Of The Electromagnetic Properties Of Materials, Saranraj Karuppuswami, Edward Rothwell, Premjeet Chahal, Michael J. Havrilla
Faculty Publications
The design, analysis, and fabrication of a prototype triaxial applicator is described. The applicator provides both reflected and transmitted signals that can be used to characterize the electromagnetic properties of materials in situ. A method for calibrating the probe is outlined and validated using simulated data. Fabrication of the probe is discussed, and measured data for typical absorbing materials and for the probe situated in air are presented. The simulations and measurements suggest that the probe should be useful for measuring the properties of common radar absorbing materials under usual in situ conditions.
Ecologically Safe Experimental Purpose Application Of Microwaves In The Treatment Of Chronic Neurological Disorders: Optimization And Risks, K. Arkhypova, A. Nosatov, M. Nurushev, P. Krasov, A. Fisun, A. Nurusheva
Ecologically Safe Experimental Purpose Application Of Microwaves In The Treatment Of Chronic Neurological Disorders: Optimization And Risks, K. Arkhypova, A. Nosatov, M. Nurushev, P. Krasov, A. Fisun, A. Nurusheva
Eurasian Journal of Physics and Functional Materials
Current paper describes the experimental dual-purpose application of microwaves in a controlled clinical trial on optimizing therapy for chronic neurological disorders. As a part of integrated treatment, low-intensity microwave-assisted blood modification has been used. It represents a physiotherapeutic method based on the autologous blood transfusion (self-blood treatment) after the short-term exposure to microwaves ( lambda = 7.2 mm). Because of beneficial clinical impact of the microwave autohemotherapy previously observed, we aimed to find a possible way to track a manifestation of nonthermal microwave effects. For this purpose, we have applied a microwave single-frequency ( lambda = 7.6 mm) dielectrometry technique …
Dielectric Properties Of Isolated Adrenal Chromaffin Cells Determined By Microfluidic Impedance Spectroscopy, A. C. Sabuncu, M. Stacey, G. L. Graviso, N. Semenova, P. T. Vernier, N. Leblanc, I. Chatterjee, J. Zaklit
Dielectric Properties Of Isolated Adrenal Chromaffin Cells Determined By Microfluidic Impedance Spectroscopy, A. C. Sabuncu, M. Stacey, G. L. Graviso, N. Semenova, P. T. Vernier, N. Leblanc, I. Chatterjee, J. Zaklit
Bioelectrics Publications
Knowledge of the dielectric properties of biological cells plays an important role in numerical models aimed at understanding how high intensity ultrashort nanosecond electric pulses affect the plasma membrane and the membranes of intracellular organelles. To this end, using electrical impedance spectroscopy, the dielectric properties of isolated, neuroendocrine adrenal chromaffin cells were obtained. Measured impedance data of the cell suspension, acquired between 1 kHz and 20 MHz, were fit into a combination of constant phase element and Cole-Cole models from which the effect of electrode polarization was extracted. The dielectric spectrum of each cell suspension was fit into a Maxwell-Wagner …
Performance Assessment Of Electromagnetic Soil Water Sensors In Different Soil Textural, Temperature, And Salinity Conditions, Jasreman Singh
Performance Assessment Of Electromagnetic Soil Water Sensors In Different Soil Textural, Temperature, And Salinity Conditions, Jasreman Singh
Department of Biological Systems Engineering: Dissertations and Theses
Determination of accurate and continuous measurements of volumetric water content (θv) is extremely valuable for irrigation management and other agronomic decisions. Lately, electromagnetic (EM) sensors are being widely used to monitor θv continuously which also offer the benefits of ease of installation, fewer regulatory and safety concerns, and cost effectiveness. However, the accuracy of parameters [soil temperature, electrical conductivity (ECa), dielectric permittivity (εra), and θv] reported by EM sensors need to be evaluated for them to be utilized for agricultural water management. In the current study, the accuracy of a wide …
Inverse Scattered Problems, Mikaela Coose
Inverse Scattered Problems, Mikaela Coose
Scholar Week 2016 - present
The research project involves the investigation of a signal processing based method for modeling and solving inverse scattering problems. Topics within the presentation may include, but not limited to: defining the problem, proposing a hypothesis, delineating research methods with computer modeling, revealing results of the conducted experiment as well as analysis of the final projected images. The goal of this research is to identify a resonance pattern for a target such as a square by sweeping the permittivity levels. Results include a visual table mapping each permittivity. Finally, a discussion of future experiments and real-world applications may be included in …
Apertureless Near-Field Scanning Probes Based On Graphene Plasmonics, Hamid T. Chorsi, John X. Zhang
Apertureless Near-Field Scanning Probes Based On Graphene Plasmonics, Hamid T. Chorsi, John X. Zhang
Dartmouth Scholarship
We present a novel approach in designing high-throughput high-resolution apertureless near-field scanning probes with enhanced nanofocusing based on graphene plasmonics. Extremely localized plasmons on graphene are mingled with nanofocusing of surface plasmon polaritons to confine and steer the plasmon waves into the apex of a near-field scanning optical microscopy tip. The Fermi level, localized emission sites on graphene, and the angle of excitation play a critical role in exciting graphene surface plasmons on the lateral walls of the designed conical probes. The optimized probes feature full-width at half-maximum (FWHM) around 25 nm, which is at least two times smaller than …
Fdtd Modeling Of Isotropic Dispersive Magnetic Materials, Jing Wu, Marina Koledintseva, James L. Drewniak, David Pommerenke
Fdtd Modeling Of Isotropic Dispersive Magnetic Materials, Jing Wu, Marina Koledintseva, James L. Drewniak, David Pommerenke
James K. Wu, M.D.
Numerical analysis using the finite-difference time-domain (FDTD) algorithm with a piecewise linear recursive convolution (PLRC) procedure for linear isotropic dispersive magnetic materials is presented. The frequency dependence of susceptibility used for this algorithm is represented in Debye, narrowband Lorentzian, and wideband Lorentzian forms, depending on the ratio of the resonance frequency and the resonance line width. Some numerical examples along with measurements are provided.
Representation Of Permittivity For Multiphase Dielectric Mixtures In Fdtd Modeling, Marina Koledintseva, J. Wu, H. Zhang, James L. Drewniak, Konstantin Rozanov
Representation Of Permittivity For Multiphase Dielectric Mixtures In Fdtd Modeling, Marina Koledintseva, J. Wu, H. Zhang, James L. Drewniak, Konstantin Rozanov
James K. Wu, M.D.
A simple method of approximating frequency characteristics of composites in a form convenient for time-domain numerical modeling is proposed. The frequency characteristics can be obtained from experiment or calculations based on the Maxwell Garnett mixing formalism. The resultant frequency characteristic might be of a complex shape corresponding to a combination of a number of absorption peaks. The approximation is made by a series of Debye-like terms using a genetic algorithm (GA). This leads to the necessity of taking a number of terms in the approximating series. Every term corresponds to its pole, i.e., the frequency where the maximum loss occurs. …
Identifying Shallow Subsurface Stratigraphy And Voids Using Dispersive Characteristics Of Electromagnetic And Surface Waves, Payman Hajiani
Identifying Shallow Subsurface Stratigraphy And Voids Using Dispersive Characteristics Of Electromagnetic And Surface Waves, Payman Hajiani
Doctoral Dissertations
"This dissertation presents the results of three manuscripts on spectral analysis of electromagnetic and seismic surface waves to detect subsurface stratigraphy and voids. In the first manuscript, a new technique was developed by utilizing spectral analysis of surface waves to detect subsurface openings. This technique applied the concept of group delay to evaluate the effects of subsurface voids on the phase shift domain. Seismic data sets were acquired at different sites where the shape, size, and depth of the void varied. In all surveys, the time delay technique precisely identified the locations of the subsurface openings. The second manuscript presents …
Verifying Molecular Dynamics Using Dielectric Spectroscopy, Joshua Dee Smith
Verifying Molecular Dynamics Using Dielectric Spectroscopy, Joshua Dee Smith
Theses and Dissertations
The electrical properties of proteins in solution are important for their structure and function. Computational biophysics studies of proteins need accurate parameters to ensure that numerical simulations match physical reality. Past work in this eld has compared the electrical properties of proteins obtained from dielectric spectroscopy to numerical simulations of proteins in water with adjustment of pKa values to try to capture the inevitable changes in electrical conformation that will occur in a complex structure such as a folded protein. However, fundamental veri cation of the charge parameters of the amino acid building blocks in common molecular dynamics software packages …
Tunable Negative Permittivity Behavior And Conductor-Insulator Transition In Dual Composites Prepared By Selective Reduction Reaction, Zi-Dong Zhang, Run-Hua Fan, Zhi-Cheng Shi, Shi-Bing Pan, Ke-Lan Yan, Kang-Ning Sun, Jing-De Zhang, Xiang-Fa Liu, Xiaolin Wang, S X. Dou
Tunable Negative Permittivity Behavior And Conductor-Insulator Transition In Dual Composites Prepared By Selective Reduction Reaction, Zi-Dong Zhang, Run-Hua Fan, Zhi-Cheng Shi, Shi-Bing Pan, Ke-Lan Yan, Kang-Ning Sun, Jing-De Zhang, Xiang-Fa Liu, Xiaolin Wang, S X. Dou
Australian Institute for Innovative Materials - Papers
We use a selective reduction reaction to fabricate a new kind of dual composite, which has a "composite-within-a-composite" structure. Based on the different reduction behavior of Fe2O3, an Fe-rich structure (Fe-Fe3O4-Al2O3) is formed in an Al-rich structure (FeAl2O4-Al2O3). The Fe-rich structure can bring down the concentration of free electrons to reduce the energy loss, without losing its metallic behaviour at the same time. Near the percolation threshold, a conductor-insulator transition appears and the dual composites show totally different electromagnetic responses, which can be well explained by effective medium theory. By controlling the parameters of the selective reduction process, we can …
Super-Resolution Imaging Using A Three-Dimensional Metamaterials Nanolens, B. D. F. Casse, W. T. Lu, Y. J. Huang, E. Gultepe, L. Menon, S. Sridhar
Super-Resolution Imaging Using A Three-Dimensional Metamaterials Nanolens, B. D. F. Casse, W. T. Lu, Y. J. Huang, E. Gultepe, L. Menon, S. Sridhar
Latika Menon
Super-resolution imaging beyond Abbe's diffraction limit can be achieved by utilizing an optical medium or "metamaterial" that can either amplify or transport the decaying near-field evanescent waves that carry subwavelength features of objects. Earlier approaches at optical frequencies mostly utilized the amplification of evanescent waves in thin metallic films or metal-dielectric multilayers, but were restricted to very small thicknesses (⪡λ, wavelength) and accordingly short object-image distances, due to losses in the material. Here, we present an experimental demonstration of super-resolution imaging by a low-loss three-dimensional metamaterial nanolens consisting of aligned gold nanowires embedded in a porous alumina matrix. This composite …