1,720,990 research outputs found
Impact Location in an Isotropic Plate Without Training
No full textABSTRACT IMPACT LOCATION IN AN ISOTROPIC PLATE WITHOUT TRAINING by Prasanna Rajbhandari The University of Wisconsin-Milwaukee, 2016 Under the Supervision of Professor Dr. Nathan Salowitz Unexpected impacts are major concerns in the aerospace industry that can cause difficulty to detect damage. Techniques have been developed to determine the impact location using piezoelectric sensors. Most existing systems require training data to develop a database of known structural responses and properties that can be referenced for location of impacts. This data collection is time consuming and if an impact and corresponding sensor data is outside the range of training data, the system may not be able to analyze it correctly. Some methods use specific sensor positions to reduce this phenomenon. Current systems typically utilize data from 3 or 4 sensors and are dependent on the knowledge of the speed of wave propagation in the material or reference data. This thesis develops a method of impact detection and location based on hyperbolic positioning suitable for isotropic homogenous plates that does not require training or knowledge of wave speed in the material. This derivation is not dependent on specific sensor layouts though sensor locations must be known and potential certain degenerate cases should be avoided. Equations were developed based on the time difference of arrival of strain waves at sensors with known location for impact location. This technique utilizes data from additional sensors to eliminate the need for training data or known propagation velocity. This technique translates Matlab code that was written based on these equations to automate the calculation and experimental validation that was performed using data from real specimens. Impact position error comparable to prior existing systems was verified
Bio-inspired stretchable network-based intelligent composites
No full textThe human skin hosts an array of sensors that are capable of detecting and interpreting many traits important to how we
function and survive. The goal of mimicking this capability in composites to create intelligent composite materials has led
to the development of a bio-inspired stretchable network composed of numerous micro-fabricated sensors capable of
detecting multiple stimuli. The components of the network are small scale and flexible making the network embeddable
within complexly shaped composite layups and flexible structures with minimal impact on the host structure. This paper
outlines recent progress in ongoing work to develop the bio-inspired network in order to create intelligent composite
materials
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Embedded Ultrasonic Inspection of Liquid Filled Pressure Vessels
No full textStructural health monitoring and ultrasonic inspection techniques can be used to inspect a structure for degradation. There are several different approaches for doing this including the use of an embedded sensing system which uses elastic wave propagation through the structure. Previous work using this method has explored ultrasonic inspection of a simple, flat plate structure, however, structures often have more complex geometry, and the flat plate offers only a basic understanding of elastic wave propagation. Therefore, experimental approaches and results drive how these techniques can be used for ultrasonic inspection of complex vessels where challenges arise due to the potential for multiple elastic wave propagation modes and paths through the complex geometry combined with effects of changing environment conditions. Research here investigates the fundamental capability of using embedded ultrasonic inspection techniques on a complex pressurized water tank structure using the previously established methods for basic structures. The investigation uses permanently mounted lead zirconate titanate piezoelectric transducers to actuate and sense ultrasonic waves propagating through the tank structure. The change in wave propagation is explored through the simulated damage of a magnet placed on the structure, filling the tank, and pressurizing the tank. The results of this work are intended to provide a basis and physics-based understanding upon which to build capabilities of structural health monitoring of liquid filled pressure vessels to detect and locate degradation under different environmental and state effects. Liquid filled pressure vessels are common in modern life, from the water heaters in our homes to the fuselage of a spacecraft. Failure of liquid filled pressure vessels can have severe consequences resulting in direct damage due to liquid release, as well as the consequences of system failure and downtime. Therefore, the use of structural health monitoring based on embedded ultrasonic systems has the potential to significantly impact the safety and reliability of a system and to save resources spent in maintenance and downtime with its ability to detect, locate, characterize, and quantify degradation of a structure.2024-08-0
Novel Non-Invasive Technology for the Detection of Thin Biofilm in Piping Systems (phase - 1)
No full textBiofilms are formed when a group of cells of microorganisms stick to each other and often on a surface. The development of biofilm has been a major issue in many fields (medical field, food, chemical, and water industry are a few such fields). In the medical field alone, biofilm infections have reportedly cost over five billion USD in additional healthcare expenses. The food industry usually halts the operation of its plant eight hours, every day to ensure that their equipment and transportation channels are clean and free from any biofilm presence. Similarly, the water and chemical industry need to ensure that their transportation channels are free from biofilm build-up to ensure that the flow rate of liquid flowing through the channels is neither affected nor contain bacterial traces. There is an immediate need for new technologies, that are both real-time and non-invasive that can be used to quantify biofilm formation in closed systems, which can reduce the loss incurred by the healthcare, food, chemical and water industry. This study investigates the use of a novel non-invasive and real-time technique that consists of two ultrasound sensors which can be mounted on a piping system. In this study, voltage and phase shifts were detected in materials with thickness greater than 40 µm, indicating that the sensor arrangement can be used to detect biofilm of thickness greater than 40 µm in a closed piping system. The results of objects present in the closed system cannot be obtained using conventional techniques such as the Raman microscopy, confocal laser scanning microscopy (CLSM) or other microscopy methods. This technique also allows in-situ detection (i.e. it avoids the need for inserting or extracting a coupon from the medium for measurement and eliminates the need to obstruct the operation of the system or the flow of measurement media through the system).2020-06-0
Experimental and Analytical Study of the Novel Static Flow Meters
No full textFlow metering is the measurement of the volume of a substance passing through a cross-sectional area per unit time. In various industries, many diverse types of flow meters are used to evaluate and control the velocity of the fluid passing through a system. In the water industry, flow meters are crucial in evaluating the performance of large scale industrial water filtration systems, and in the detection of underperforming elements. Reliable flow metering technology is essential to guarantee the production of clean safe drinking water. An ongoing issue with existing flow metering technologies is cost-effectiveness. This is a major limiting factor for widespread use. One of the focuses of this research was expense reduction of the system and the final product. The end goal was to create and validate designs for low cost static, and robust flow sensors. The objective of this project was to design a simple, easily manufactured flow meter with no moving parts. By reducing the cost, precision is sacrificed in some aspects, however, the design still proved to be a viable substitution. Differential pressure flow metering was selected based on target and orifice plate meters to generate the main idea of the project. Simple designs were pursued utilizing strain gauges and basic data acquisition systems, and ultimately three designs were created. The general design methodology involved mounting a strain gauge on a custom designed laser cut Acrylic plate, and inserting it as a pipe cross section to target water flow. For each design equations were analytically derived and specimens were created with varying geometric parameters. A multi-level factorial analysis was performed on each design to identify which geometric properties were critical to flow sensitivity. Three variables (thickness, length, width) for each design were studied based on the derived equations. Based on the results, the thickness of the designed plate was the most effective parameter in ensuring accuracy. Lower thickness leads to a more sensitive system and better results. Width and Length of the cut area on which strain gauge was mounted were other geometric properties thoroughly studied. Designs were developed that were found to be inert to certain potential manufacturing variation through analytical analysis with experimental validation. Beam bending was a critical component to all the designs created. One design was created that measured flow independent of beam width, and another was created which produced results independent of beam length. Across all designs, sensitivity and flow measurement were highly sensitive to the thickness of the beam.2021-06-0
Novel Non-Invasive Technology for the Detection of Thin Biofilm in Piping Systems (phase - 1)
No full textBiofilms are formed when a group of cells of microorganisms stick to each other and often on a surface. The development of biofilm has been a major issue in many fields (medical field, food, chemical, and water industry are a few such fields). In the medical field alone, biofilm infections have reportedly cost over five billion USD in additional healthcare expenses. The food industry usually halts the operation of its plant eight hours, every day to ensure that their equipment and transportation channels are clean and free from any biofilm presence. Similarly, the water and chemical industry need to ensure that their transportation channels are free from biofilm build-up to ensure that the flow rate of liquid flowing through the channels is neither affected nor contain bacterial traces. There is an immediate need for new technologies, that are both real-time and non-invasive that can be used to quantify biofilm formation in closed systems, which can reduce the loss incurred by the healthcare, food, chemical and water industry. This study investigates the use of a novel non-invasive and real-time technique that consists of two ultrasound sensors which can be mounted on a piping system. In this study, voltage and phase shifts were detected in materials with thickness greater than 40 µm, indicating that the sensor arrangement can be used to detect biofilm of thickness greater than 40 µm in a closed piping system. The results of objects present in the closed system cannot be obtained using conventional techniques such as the Raman microscopy, confocal laser scanning microscopy (CLSM) or other microscopy methods. This technique also allows in-situ detection (i.e. it avoids the need for inserting or extracting a coupon from the medium for measurement and eliminates the need to obstruct the operation of the system or the flow of measurement media through the system).2020-06-0
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