Engineering Commons^™

Optimum Design For Maximun Wavelength Resolution For An Edge Filter Based Ratiometric System, Qiang Wu, Ginu Rajan, Pengfei Wang, Yuliya Semenova, Gerald Farrell

Articles

In this letter, we propose a high resolution temperature insensitive interrogation technique for FBG sensors where one FBG acts as an edge filter to interrogate a separate FBG sensor. A high resolution of better than 5 με in strain measurement range from 0 to 1100 με and the best resolution of better than 1 με were verified by experiments. An error of only ±2.2 με is achieved over a temperature range from 15 to 50 °C, indicating that this strain interrogation technique is temperature insensitive. Using an altered system configuration, the temperature was also measured simultaneously with a resolution better …

A Hybrid Fiber Optic Sensing System For Simultaneous Strain And Temperature Measurement And Its Application, Ginu Rajan, Karolina Milenko, Piotr Lesiak, Yuliya Semenova, Anna Boczkowska, Manjusha Ramakrishnan, Kazimierz Jedrzejewski, Andrzej Domanski, Tomasz Wolinski, Gerald Farrell

Articles

A hybrid fiber optic sensor by integrating polarimetric fiber sensors and fiber Bragg grating sensors for simultaneous strain and temperature measurement is presented in this paper. Two types of polarimetric fiber sensors are used; a Panda fiber and a polarization maintaining photonic crystal fiber. The polarimetric strain sensors give the average strain and temperature information, while the fiber Bragg grating sensors give localized strain information. Two applications of the proposed configuration are also demonstrated in this paper. In the composite materials three fiber sensors are used while for other engineering applications a temperature insensitive polarimetric fiber sensor can be used …

Simple Design Technique For A Triangular Fbg Filter Based On A Linearly Chirped Grating, Qiang Wu, Gerald Farrell, Yuliya Semenova

Articles

A novel and simple design technique for triangular spectrum response of fibre Bragg grating (FBG) is pre- 21 sented based on a linear chirped grating. It is shown that this method is fast and can give a straightfor- 22 ward solution to meet a design target. The numerical simulation examples verified the effectiveness of 23 the design method. A general approach to design for multichannel triangular spectral responses for 24 FBG filters is proposed, which provides a solution that achieves a minimum change of refractive index 25 for the fibre.

Humidity Sensor Based On A Photonic Crystal Fiber Interferometer, Jinesh Mathew, Yuliya Semenova, Ginu Rajan, Gerald Farrell

Articles

A photonic crystal fiber interferometer that operates in reflection mode for humidity detection is presented for the first time which has the advantage that it does not require the use of any hygroscopic material. The fabrication of the sensor head is therefore simple since it only involves cleaving and splicing. The all-silica nature of the device has the potential for many applications.

Experimental Demonstration Of A Simple Displacement Sensor Based On A Bent Singlemode-Multimode-Singlemode (Sms) Fiber Structure, Qiang Wu, Yuliya Semenova, Pengfei Wang, Agus Hatta, Gerald Farrell

Articles

A simple displacement sensor based on a bent singlemode-multimode-singlemode (SMS) fiber structure is proposed and experimentally investigated. The sensor offers a wider displacement range, not limited by the risk of fiber breakage, as well as a three-fold increase in displacement sensitivity by comparison with a straight SMS structure sensor. This sensor can be interrogated by either an optical spectral analyzer (OSA) or a ratiometric interrogation system: (1) if interrogated by an OSA assuming a resolution of 1 pm, it has a sensitivity of 28.2 nm for a displacement measurement range from 0 to 280 μm; (2) if interrogated by a …

Strain Sensor Based On A Pair Of Single-Mode-Multimode-Single-Mode Fiber Structures In A Ratiometric Power Measurement Scheme, Agus Hatta, Yuliya Semenova, Qiang Wu, Gerald Farrell

Articles

The strain and temperature dependencies of a step-index single-mode–multimode–single-mode (SMS) fiber structure are investigated numerically and experimentally. For intensity-based strain measurement using a single SMS fiber structure, at a selected wavelength, it is found that there is a high strain dependence, but also a temperature dependence that will induce strain measurement error. To minimize the temperature-induced strain measurement error, two SMS fiber structures are proposed and demonstrated in a ratiometric power measurement scheme; one SMS structure acts as the strain sensor, and the other SMS structure acts as the temperature monitor. The extracted temperature information is used to determine a …

A Study Of The Effect Of The Position Of An Edge Filter Within A Ratiometric Wavelength Measurement System, Qiang Wu, Pengfei Wang, Yuliya Semenova, Gerald Farrell

Articles

The effect of the position of an edge filter within a ratiometric wavelength measurement system was investigated based on three cases: (1) the reflected fibre Bragg grating (FBG) signal passes through both the reference arm and the edge filter arm, (2) the reflected FBG signal is connected directly to the edge filter arm and does not pass through the reference arm, (3) the edge filter sits in line with the FBG and thus the source power is filtered prior to reaching the FBG. Both numerical simulations and experimental results show that cases 1 and 2 have similar system performance whilst …

A Bend Loss Based Singlemode Fiber Micro-Displacement Sensor, Pengfei Wang, Yuliya Semenova, Qiang Wu, Gerald Farrell

Articles

An all-fiber displacement sensor with a simple configuration is proposed and investigated theoretically and experimentally. The proposed fiber displacement sensor consists of a half-loop structure of high-bend loss singlemode fiber-1060XP. A ratiometric power measurement system for interrogating the proposed sensor is also presented. By measuring the change in ratio of bend loss in the ratiometric measurement system, a change in displacement can be measured assuming the ratiometric system is calibrated. The proposed macrobending fiber based displacement sensor achieves a competitive resolution of circa 0.33 μm and also benefits from simplicity compared with the conventional fiber Bragg grating based displacement sensor. …

Electron-Electron Scattering In A Double Quantum Dot: Effective Mass Approach, S. Yu. Kruchinin, A. V. Federov, A. V. Baranov, Tatiana Perova, Kevin Berwick

Articles

We present a theoretical description of the first-order scattering of interacting electrons and holes in a double quantum dot. Assuming infinitely high walls, strong confinement, and a two-band approximation, we derive general expressions for the two-particle matrix elements of the screened Coulomb potential. We also determine the selection rules for different scattering channels and consider special cases where the corresponding matrix elements can be represented by simple analytical expressions. Numerical calculations of the matrix elements and an analysis of their dependence on the geometrical and material parameters of the double quantum dot have also been performed.

A Voltage Sensor Based On A Singlemode-Multimode-Singlemode Fiber Structure, Agus Hatta, Yuliya Semenova, Ginu Rajan, Gerald Farrell

Articles

A voltage sensor based on a singlemode-multimodesinglemode (SMS) fiber structure, attached to a piezoelectric (PZT), utilized in a ratiometric optical power measurement scheme is proposed. The elongation of the PZT due to an applied voltage induces a strain on the SMS fiber structure and in turn results in a change in the transmission loss response of the SMS fiber structure. It is found that at selected wavelengths, a strong voltage dependence for the transmission loss of the SMS fiber structure can be achieved. The voltage information can be obtained from the power ratio of the system, assuming the system is …

Xperts And Novices: Differences In Their Use Of Mental Representation And Metacognition In Engineering Design, Raymond Anthony Dixon

Dissertations

Research shows that mental representation such as analogical reasoning is a fundamental cognitive tool for design problem solving (Daugherty & Mentzer, 2008; Hey, Lensey, Agogino, & Wood, 2008; Lewis, 2008). Not much is known, however, about the way students and professional engineers actively generate and change their mental representation when solving a engineering design problem. There are very few studies that show how different types of mental representations; such as metaphors, propositions, and analogies; interplay with higher order cognitive processes; such as planning, monitoring, and evaluation; as engineering designers navigate their problem and solution spaces. This empirical study investigated the …

A Case Study: Teaching Engineering Concepts In Science, David R. Stricker

Reports of Center Studies

This study was conducted to describe a teacher developed high school engineering course, to identify teaching strategies used in the process of delivering math and science literacy through this course, to identify challenges and constraints that occurred during its development and delivery, and to describe the strategies that were used to overcome those obstacles.

A case study was conducted using semi-structured interviews with the engineering instructor at Benilde-St. Margaret's in St. Louis Park, Minnesota. In addition, the researcher conducted classroom observations and reviewed instructional materials, teacher lesson plans, and teacher journals.

Themes that developed regarding the strategies used to deliver …

Optimization, An Important Stage Of Engineering Design, Todd R. Kelley

Publications

The presents information on optimization, an important stage of engineering design. Criteria and design constraints are used in the optimization stage of the engineering design process to allow the designer to locate the optimal solution. Before initiating a prototype work, both analysis and optimization are done in designing a product. Optimization is done to create the best design relative to a set of prioritized criteria or constraints, including maximizing factors such as productivity, strength, reliability, longevity, efficiency and utilization.

Stem Education And Leadership: A Mathematics And Science Partnership Approach, Chris Merrill, Jenny Daugherty

Publications

The issue of attracting more young people to choose careers in science, technology, engineering, and mathematics (STEM) has become critical for the United States. Recent studies by businesses, associations, and education have all agreed that the United States’ performance in the STEM disciplines have placed our nation in grave risk of relinquishing its competitive edge in the marketplace (e.g., Rising above the gathering storm, 2007). A Congressional Research Service (2006) report stated that, a “large majority of secondary students fail to reach proficiency in math and science, and many are taught by teachers lacking adequate subject matter knowledge” (Congressional Research …

Engineering Student Outcomes For Infusion Into Technological Literacy Programs: Grades 9-12, Craig Rhodes, Vincent Childress

Publications

In 2004, the National Center for Engineering and Technology Education (NCETE) secured funding from the National Science Foundation (NSF) to infuse engineering design into the schools through technology education. In order to reach this goal the researchers, in cooperation with NCETE, conducted a two phase study to identify outcomes for high-school students studying engineering. The first study (referred to as a Phase I) focused on students who intended to enter an engineering program after high school, answering the question:

What are the engineering student outcomes that prospective engineering students in grades 9 through 12 should know and be able to …

Design, Development And Biomechanical Analysis Of Scaffolds For Augmentation Of Rotator Cuff Repairs, Amit Aurora

ETD Archive

Rotator cuff tears are a source of debilitating pain that commonly affects more than 40 of our aging population. Despite advances in surgical treatment, the failure rate of rotator cuff repairs is as high as 20-90 . Extracellular matrix (ECM) derived scaffolds have recently been investigated as augmentation devices for rotator cuff repairs, but none has yet demonstrated both the appropriate biological and mechanical properties for mitigating re-tears and enhancing healing. This dissertation proposes to engineer the mechanical properties of allograft fascia lata in a manner that will allow its use as an augmentation device for rotator cuff repairs. This …

A Major Study Of American (Ford) Compared With Japanese (Honda) Automotive Industry: Their Strategies Affecting Surviabilty, Patrick F. Callihan

ETD Archive

Understanding the role of technology, in the automotive industry, is necessary for the development, implementation, service and disposal of such technology, from a complete integrated system life cycle approach, to assure long-term success. This dissertation provides a unique complete characterization of the system life (cycle) business major cost elements of the automotive industry the subsystems, cost elements, interplay and interdependencies that affect the total real life cycle cost and value the various stated product, organizational, and process initiatives intended to produce significant improvements in the American automobile industry, as compared to the Japanese. This dissertation adds a perspective, understanding, and …

A Computational Study For The Utilization Of Jet Pulsations In Gas Turbine Film Cooling And Flow Control, Olga V. Kartuzova

ETD Archive

Jets have been utilized in various turbomachinery applications in order to improve gas turbines performance. Jet pulsation is a promising technique because of the reduction in the amount of air removed from compressor, which helps to increase turbine efficiency. In this work two areas of pulsed jets applications were investigated, first one is film cooling of High Pressure Turbine (HPT) blades and second one is flow separation control over Low Pressure Turbine (LPT) airfoil using Vortex Generator Jets (VGJ) The inlet temperature to the HPT significantly affects the performance of the gas turbine. Film cooling is one of the most …

Surface Microtopography Modulation Of Biomaterials For Bone Tissue Engineering Applications, Eun Jung Kim

ETD Archive

The ultimate goal of this project is to develop a biodegradable and implantable scaffold with precise surface topographies that can provide osteoconductive stimuli to connective tissue progenitor cells (CTPs), and subsequently, enhance bone regeneration applications without the complications of autogenous cancellous bone grafts. This dissertation presents the modification of surface microtextures to provide osteoconductive stimuli to CTPs for bone regeneration applications. First, the effect of surface topography on cell proliferation and osteogenic differentiation was validated through experiments using surface post microtextures and CTPs. Post microtextures accelerated CTP growth behaviors compared to smooth polydimethylsiloxane (PDMS) and standard cell culture dishes. Second, …

Developing A Protocol For An Environmentally Preferable Purchasing Plus (Epp+) Program At Nasa Glenn Research Center, Amarin Kongtawelert

ETD Archive

EPP+ or Environmentally Preferable Purchasing Plus is a Environmentally Preferable Purchasing program with incorporated a unique Life Cycle Assessment (LCA) scoring system which implemented at NASA, Glenn Research Center. A protocol has been developed to aid in selecting among products based on principles of Environmentally Preferable Purchasing (EPP) and Life Cycle Assessment (LCA). The protocol has been developed for use at NASA Glenn Research Center (GRC) but is intended to benefit anyone wishing to make sustainable purchasing decision. The protocol was designed as a web-based application which evaluates the life cycle factors, affirmative procurements, price, and performance of products that …

Evaluation Of Upper Motor Neuron Pathology In Amyotrophic Lateral Sclerosis By Mri;Towards Identifying Noninvasive Biomarkers Of The Disease, Venkateswaran Rajagopalan

ETD Archive

Amyotrophic lateral sclerosis (ALS) is the commonest adult motor neuron disease (MND) which causes progressive muscle paralysis and death usually within 5 years of symptom onset. As a result, only ╠â30,000 individuals in the United States are afflicted at any one time even though 5,000 or more individuals are diagnosed yearly. The diagnosis of ALS requires evidence of degeneration in upper motor neurons (UMNs) in the brain and in lower motor neurons (LMNs) that exit the brainstem and spinal cord to innervate skeletal muscles. Diagnosis can be incorrect or delayed when disease is early or atypical because non-invasive objective tests …

Cell-Taught Gene Therapy For The Preservation And Regeneration Of Cardiac Tissue Following Chronic Heart Failure, Srividya Sundararaman

ETD Archive

Heart failure is the primary cause of mortality and morbidity in the Western world. Although cell therapy has demonstrated improvement in cardiac function, these benefits are being attributed to the activation of paracrine factors, rather than the differentiation and integration of the transplanted cells into the host tissue. Based on this knowledge the focus of this thesis work was to deliver paracrine factors, and evaluate its effect on cardiac function. Gene therapy has evolved as a promising option to deliver pro-angiogenic proteins to infarct zones, thus providing cardiac benefit. This study has identified a gene design without the use of …

A Comparative Study On Fault Detection And Self-Reconfiguration, Ning Ge

ETD Archive

Extended State Observer (ESO) and the Alpha-Beta-Gamma Tracker are introduced and compared. In comparison, the ESO is found to be more noise resistant. The extended state used for the estimation of the general system dynamics in real time makes it suitable for fault detection. Four control schemes are proposed for self-reconfiguration upon fault detection. These schemes are Active Disturbance Rejection Control, Tracker-based Feedback Control, Fuzzy Logic Control and Tracker-based PID Control. To compare their control performance, these schemes are applied to three different applications namely Active Engine Vibration Isolation System, Three-Tank Dynamic System and MEMS Gyroscope System. The advantages and …

The Thermodynamics Of Fluid-Phase Benzene Via Molecular Simulation, John L. Tatarko

ETD Archive

Accurate values for thermodynamic properties throughout the fluid phase are a requirement for the design of separation processes. To date, very few pure substances have been completely characterized because of time and monetary constraints. Low cost computing power now permits complete determination of the thermodynamic properties of pure substances via molecular simulation. Molecular simulation is computational statistical mechanics. Benzene is an important industrial chemical and pharmaceutical precursor. It is the prototypical, symmetric, hexagonal molecule and is an ideal candidate for molecular simulation. The molecular models of three researchers in the field are submitted for Monte Carlo simulation in the virtual …

Flow Induced Vibrations In Pipes: A Finite Element Approach, Ivan Grant

ETD Archive

Flow induced vibrations of pipes with internal fluid flow is studied in this work. Finite Element Analysis methodology is used to determine the critical fluid velocity that induces the threshold of pipe instability. The partial differential equation of motion governing the lateral vibrations of the pipe is employed to develop the stiffness and inertia matrices corresponding to two of the terms of the equations of motion. The equation of motion further includes a mixed-derivative term that was treated as a source for a dissipative function. The corresponding matrix with this dissipative function was developed and recognized as the potentially destabilizing …

Identification Of Unmodeled Dynamics In Rotor Systems Using Mu-Synthesis Approach, Ryan J. Madden

ETD Archive

It is well recognized that analytical models only approximate the true dynamics of analyzed rotating machines, due to the presence of components that are inherently difficult to model. Such models of rotating machines are driven by the best engineering knowledge and experience, and very often are updated based on experimental results. The problem of unmodeled or missing dynamics can be exacerbated in the presence of rotor structural damage such as a transverse crack on a shaft. This thesis will present an effective approach for model updating using advanced tools developed in robust control theory, specifically mu-synthesis. The methodology will be …

Automatic Utility Meter Reading, Kaicheng Xie

ETD Archive

This thesis discusses research in the automation of reading a utility meter. The hardware required is a wireless camera pointed at the meter to be read. This meter can be a water, electricity or gas meter. After the wireless camera collects the image from the utility meter it transmits the image to a computer through a receiver. The computer analyzes the image with pattern recognition technology to obtain the numbers. We use image processing techniques in this thesis, including image preprocessing, image segmentation (Otsu threshold method), and number recognition. Finally we create a graphical user interface using Visual C#®

Reverse Engineering Aspects To Derive Application Class Models, Irenee Morcos George Magdalla

ETD Archive

Aspects provide a nice way to modify behavior and implement cross-cutting concerns in object-oriented systems. As such, aspects do not have an existence of their own the application classes that the aspects refer to must be present in order to instantiate the aspects. In this research, we present a reverse engineering approach to generate a minimal class model that has all the structural elements necessary in order to complete exercise a set of aspects

A Generalized Inverter Control Method For A Variable Speed Wind Power System Under Unbalanced Operating Conditions, Shuang Wu

ETD Archive

This thesis presents a generalized control method for complete harmonic elimination and adjustable power factor of a grid side inverter under unbalanced operating conditions used in variable speed wind power systems. The theoretical analysis of the proposed control method is described and verified by simulation in Simulink®. Two types of traditional control methods are also explained and applied in the wind power system for comparison, which are the indirect current control in a-b-c reference frame and the active and reactive power control in d-q synchronous frame. This method is verified for the gird fault right-through operation as well

Directional Solidification Of Al - 7 Wt Si Alloy, Ravi Shanker Rajamure

ETD Archive

Al - 7 wt Si alloy has been directionally solidified from an aluminum single crystal seed with its [100] orientation parallel to the growth direction with a positive thermal gradient of 40 K/cm and over the range of growth speeds. Growth speed dependence of primary Dendrite Spacing and Primary Dendrite trunk Diameter has been analyzed during the step increase and step decrease in the growth speeds. Frequency distribution of Nearest Neighbor dendrites obtained from the statistical analysis shows the hexagonal distribution of dendrites. The interdendritic convection was present in the form of transverse macrosegregation and non uniform distribution of dendrites …