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2016

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Articles 751 - 780 of 1539

Full-Text Articles in Mechanical Engineering

Analysis Of An Artificial Tailplane Icing Flight Test Of A High-Wing, Twin-Engine Aircraft, Shehzad Maksudahmad Shaikh May 2016

Analysis Of An Artificial Tailplane Icing Flight Test Of A High-Wing, Twin-Engine Aircraft, Shehzad Maksudahmad Shaikh

Mechanical and Aerospace Engineering Theses - Archive

The US Air Force Flight Test Center (AFFTC) conducted a civilian, Federal Aviation Administration (FAA) sponsored, evaluation of tailplane icing of a twin-turboprop business transport at Edwards Air Force Base. The flight test was conducted to evaluate ice shape growth and extent of ice on the tailplane for specific weather conditions of Liquid Water Content (LWC), droplet size, and ambient temperature. This work analyzes the flight test data comparing the drag for various tailplane icing conditions with respect to a flight test verified calibrated aircraft model. Although less than a third of the test aircraft was involved in the icing …

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A Mesh Based Boom To Stop Oil Spread, Bharathram Visweswaran May 2016

A Mesh Based Boom To Stop Oil Spread, Bharathram Visweswaran

Mechanical and Aerospace Engineering Theses - Archive

In this work, we develop a new boom to separate oil and water. In a commonly used boom, a membrane that has no pores is normally used to block oil spread. Since this membrane also blocks water flow, high pressure is easy to build on such a membrane to break or damage it. To solve this problem, in the new boom, the membrane is replaced with a hydrogel-coated mesh. The hydrogel-coated mesh has dual properties of superhydrophilicity and superoleophobicity. Accordingly, water can still go through the mesh, while oil cannot. Subsequently, liquid pressure on the mesh is reduced. In this …

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Analysis Of Electric Double Layer Structure Formed During Corrosion Of Steel Pipes Carrying Potable Water, Tanmay Sanjeev Gupte May 2016

Analysis Of Electric Double Layer Structure Formed During Corrosion Of Steel Pipes Carrying Potable Water, Tanmay Sanjeev Gupte

Mechanical and Aerospace Engineering Theses - Archive

Corrosion of steel pipes carrying drinking water is a universal issue. It affects human health as the corrosion sediments in these pipes can be toxic and unfit for consumption. Further, the amassing of the corrosion products can lead to operational difficulties. Drinking water consists of anions like carbonate, hydroxides and chloride ions which are responsible for the corrosion process. In such types of aqueous corrosion, there is an interfacial region formed between the corroding metal and the bulk of the aqueous environment. This interfacial region is called the Electrical Double Layer. In this article, we direct to study the effects …

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Reliability Challenges In Airside Economization And Oil Immersion Cooling, Jimil Manojbhai Shah May 2016

Reliability Challenges In Airside Economization And Oil Immersion Cooling, Jimil Manojbhai Shah

Mechanical and Aerospace Engineering Theses - Archive

The Datacom facility which comprises rooms or closets used for communication, computers/servers or electronic equipment requires cooling unit which consumes 31% (23% HVAC cooling + 8% HVAC fans) of overall energy. The ASHRAE TC9.9 subcommittee, on Mission Critical Facilities, Data Centers, Technology Spaces, and Electronic Equipment, has suited the data center’s executives by permitting brief period outings of the environmental conditions outside the prescribed temperature-humidity range, into passable extents A1-A4. To comprehend the expanding server densities and the required cooling vitality costs, data center operators are falling back on cost cutting measures. For instance, they are not firmly controlling the …

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Harvesting Of Water From Fog Using Sponges, Jae Jun Lee May 2016

Harvesting Of Water From Fog Using Sponges, Jae Jun Lee

Mechanical and Aerospace Engineering Theses - Archive

Supervising Professor: Cheng Luo A sponge has porous structures. It is capable of both storing and transmitting water. In this work, we explored the possibility of applying three different types of sponges to collect fog. We also compared their fog-collection efficiencies with that of a typical Raschel mesh that is widely used in the field to collect fog. We found that, for three different fog speeds, the fog-collection efficiencies of three tested sponges were 39% to 93% those of the typical Raschel mesh, indicating that the sponges could serve as alternative fog collectors when well-developed collectors were not available. Sponge …

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Microspine Gripping Mechanism For Asteroid Capture, Ezekiel G. Merriam, Andrew B. Berg, Andrew Willig, Aaron Parness, Tim Frey, Larry L. Howell May 2016

Microspine Gripping Mechanism For Asteroid Capture, Ezekiel G. Merriam, Andrew B. Berg, Andrew Willig, Aaron Parness, Tim Frey, Larry L. Howell

Student Works

This paper details the development and early testing of a compliant suspension for a microspine gripper device for asteroid capture or micro-gravity percussive drilling. The microspine gripper architecture is reviewed, and a proposed microspine suspension design is presented and discussed. Prototyping methods are discussed, as well as testing methods and results. A path forward is identified from the results of the testing completed thus far. Key findings include: the microspine concept has been established as a valid architecture and the compliant suspension exhibits the desired stiffness characteristics for good gripping behavior. These developments will aid in developing the capability to …

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Analysis Of Shock-Plugs In Quasi-One-Dimensional Compressible Flow, Matthew Alexander Thompson May 2016

Analysis Of Shock-Plugs In Quasi-One-Dimensional Compressible Flow, Matthew Alexander Thompson

Graduate Theses - Mechanical Engineering

At small length scales, such as in micro-nozzles, the assumption that a shock wave is infinitesimally thin breaks-down due to the thickness of the shock being non-negligible compared to the dimensions of the nozzle. In this thesis, shock waves of finite thickness, or “shock-plugs,” are modeled using the same methods and assumptions as a standard shock wave analysis. Due to the finite thickness of shock-plugs, however, two additional parameters are required in order to account for the differing inlet and exit areas, as well as the pressure on the side walls of the channel. A “typical” micro-nozzle with appropriate dimensions …

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Optical Analysis And Fabrication Of Micro And Nanoscale Plasmonically Enhanced Devices, Avery M. Hill May 2016

Optical Analysis And Fabrication Of Micro And Nanoscale Plasmonically Enhanced Devices, Avery M. Hill

Mechanical Engineering Undergraduate Honors Theses

Plasmonic nanostructures have been shown to act as optical antennas that enhance optical devices due to their ability to focus light below the diffraction limit of light and enhance the intensity of the incident light. This study focuses on computational electromagnetic (CEM) analysis of two devices: 1) GaAs photodetectors with Au interdigital electrodes and 2) Au thin-film microstructures. Experiments showed that the photoresponse of the interdigital photodetectors depend greatly on the electrode gap and the polarization of the incident light. Smaller electrode gap and transverse polarization give rise to a larger photoresponse. It was also shown that the response from …

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The Child Brain Computes And Utilizes Internalized Maternal Choices, S. Seung-Lark Lim, J. Cherry C. Bradley, A. Davis, S. N. Balakrishnan, O. Ha, J. Bruce, A. Bruce May 2016

The Child Brain Computes And Utilizes Internalized Maternal Choices, S. Seung-Lark Lim, J. Cherry C. Bradley, A. Davis, S. N. Balakrishnan, O. Ha, J. Bruce, A. Bruce

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Material Evaluation Of A Lightweight, Automated Canned Pet Food Dispenser, Kathryn Marie Carr May 2016

Material Evaluation Of A Lightweight, Automated Canned Pet Food Dispenser, Kathryn Marie Carr

Honors Capstones

No abstract provided.

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Temporally And Spatially Resolved Quantification Of Hemodynamic Forces And Endothelial Mechanics, Lori M. Lambert May 2016

Temporally And Spatially Resolved Quantification Of Hemodynamic Forces And Endothelial Mechanics, Lori M. Lambert

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The endothelium is a thin layer of endothelial cells that line the interior surface of an artery. Due to their direct contact with blood flow, endothelial cells experience varying hemodynamic forces and respond to these forces by altering their morphology. When plaque and other substances accumulate in the walls of arteries, i.e., atherosclerosis, endothelial cells have abnormal responses to blood flow. Studying atherosclerosis progression is, therefore, a two-fold investigation into 1) the hemodynamic forces that cause endothelial responses, and 2) the biological and mechanical responses of endothelial cells. The ultimate goal of this study was to develop an experimental …

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Haul Truck Tires Recycling, Jessica N. Lizarazu May 2016

Haul Truck Tires Recycling, Jessica N. Lizarazu

Chemical Engineering Undergraduate Honors Theses

The disposal of large Off-the-Road (OTR) tires is an increasingly important concern. These tires can weigh up to 8,450 pounds with an overall diameter and width of approximately 140.7 inches and 45.1 inches respectively. OTR tires are used for mining vehicles such as haul trucks, wheel loaders, backhoes, graders, and trenchers. These new tires cost between $38,000 and $50,000 each, depending on multiple factors including oil prices and the cyclical nature of the industry. Haul trucks contain six tires per vehicle, and mines replace these tires around every 9-12 months. Statistics regarding discarded OTR tires are not provided by the …

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Direct Printing Of Microstructures By Femtosecond Laser Excitation Of Nanocrystals In Solution, W. Shou, Heng Pan May 2016

Direct Printing Of Microstructures By Femtosecond Laser Excitation Of Nanocrystals In Solution, W. Shou, Heng Pan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Strong Coupling Between Mid-Infrared Localized Plasmons And Phonons, W. Wan, Xiaodong Yang, Jie Gao May 2016

Strong Coupling Between Mid-Infrared Localized Plasmons And Phonons, W. Wan, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Cooling And Packaging Of Accumulators For Formula Sae Electric Car, Hang Yin May 2016

Cooling And Packaging Of Accumulators For Formula Sae Electric Car, Hang Yin

Mechanical and Aerospace Engineering Theses - Archive

Electric car is the future of automotive industry. The performance of the batteries is vital for that of electric cars. Overheating will compromise the performance of batteries, shorten the life span and even damage the battery permanently. So it is crucial to have an efficient packaging and cooling method. This project using Formula SAE Electric car as the testing ground is dedicated to develop the efficient way of thermal and electronic packaging of accumulators for automobiles.

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Development And Flight Test Of Moving-Mass Actuated Unmanned Aerial Vehicle, Sampath Reddy Vengate May 2016

Development And Flight Test Of Moving-Mass Actuated Unmanned Aerial Vehicle, Sampath Reddy Vengate

Mechanical and Aerospace Engineering Theses - Archive

Conventional airplane control is achieved by aerodynamic control surfaces by generating moments around all the three axes of the aircraft. Defections of the control surfaces have some disadvantages such as induced drag, increase in radar signature, and exposure to high temperature in high speed applications. As an alternative moment generation mechanism, prior research proposed internal mass-actuation, which is to generate gravitational moment by changing the center of gravity of the aircraft through motion of internal masses within the aircraft. Prior research investigated the feasibility and benefit of internal mass-actuation in airplane control based on simulation analysis. The main focus of …

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Numerical Studies On Spin Coating Of Metals, Varun Nanjunda Rao Viswamithra May 2016

Numerical Studies On Spin Coating Of Metals, Varun Nanjunda Rao Viswamithra

Mechanical and Aerospace Engineering Theses - Archive

Spin coating is a surface coating process which involves spreading a liquid dispensed on the center of a rotating substrate. The liquid is discharged using a suitable method on to the substrate rotating at a constant angular speed. The spinning speed is controlled to obtain a coating of desired thickness with faster spinning resulting in thinner coating. The thickness of the coating also depends on the properties of the fluid and other process parameters. Centrifugal force is introduced into the code as radial component of acceleration. The first part of the code solves the continuity and the Navier-Stokes equations, with …

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Cfd Analysis And Design Optimization Of Heat Sink For Oil Immersion Cooling, Koushik Epuri May 2016

Cfd Analysis And Design Optimization Of Heat Sink For Oil Immersion Cooling, Koushik Epuri

Mechanical and Aerospace Engineering Theses - Archive

Air cooling is predominant cooling technique employed in most of the data centers. As the demand for High performance computing (HPC) which deploy large concentration of high-end servers (30 kW to 200 kW per rack) is increasing, it is becoming challenging to cool the systems using air cooling. Liquid cooling has significant advantages over air cooling techniques due to higher heat capacities of fluids. Liquid immersion cooling using dielectric and non-corrosive mineral oils is one of the potential alternative to air cooling methods for high density data centers. In this work, we consider a third generation open compute server optimized …

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Design And Stiffness Optimization Of Quadri-Directional Composite Grid Lattice Structures, Gajendra Devanga Gangadara May 2016

Design And Stiffness Optimization Of Quadri-Directional Composite Grid Lattice Structures, Gajendra Devanga Gangadara

Mechanical and Aerospace Engineering Theses - Archive

Composite grid structures are rib stiffeners connected to each other rigidly in a pattern or a lattice such that the whole grid pattern has certain smeared stiffness property and has a certain structural behavior. The main focus of this thesis is to design the geometric pattern of a Quadri-directional composite grid lattice such that it has the prescribed stiffness moduli. The research is divided into three phases, in the first phase, the equation for stiffness moduli, the reduced stiffness matrix [Q] and the laminate stiffness matrices [ABD] of the grid pattern is derived for Quadri-directional grid panels. In the second …

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Atomic Force Microscopy Based Dna Analysis, Drew Creighton May 2016

Atomic Force Microscopy Based Dna Analysis, Drew Creighton

Mechanical Engineering Undergraduate Honors Theses

This report explores dry and wet scanning of a surface and DNA pickup using an AFM, as well as fluorescent staining of DNA. Dry and wet scans of DNA were obtained using a cantilever AFM tip in tapping mode. Dry scans were found to be clearer than wet scans; however, the drying process was found to decrease the thickness of DNA 2–4 times less than its original thickness. Alternately, wet scans were found to be less clear than dry scans and introduced more noise into the images obtained. Additionally, DNA kept its initial thickness during wet scanning. DNA was capable …

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Cfd Model For Ventilation In Broiler Holding Sheds, Christian Heymsfield May 2016

Cfd Model For Ventilation In Broiler Holding Sheds, Christian Heymsfield

Biological and Agricultural Engineering Undergraduate Honors Theses

Broiler production in Arkansas was valued at over $3.6 billion in 2013 (University of Arkansas Extension of Agriculture). Consequently, improvement in any phase of the production process can have significant economic impact and animal welfare implications. From the time poultry leave the farm and until they are slaughtered, they can be exposed to harsh environmental conditions, both in winter and in summer. After road transportation, birds are left to wait in holding sheds once they arrive at the processing plant, for periods of approximately 30 minutes to two hours. This project was interested in this holding shed waiting time during …

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Particle Image Velocimetry Design & Installation, Zach Ritchie May 2016

Particle Image Velocimetry Design & Installation, Zach Ritchie

Mechanical Engineering Undergraduate Honors Theses

This work will mainly focus on the design, construction, and installation of the Particle Image Velocimetry (PIV) system in the Chemical Hazards Research Center wind tunnel. The PIV system utilizes a Class IV (double pulsed) laser, optics to produce a light sheet, timing circuitry, and a high-resolution camera (with buffered output) to measure a system’s velocity (two-dimensional) field by determining the displacement of particles over the time between laser pulses. For maximum mobility and functionality, the PIV system was installed in the center of the tunnel on a moveable cart with the laser and camera mounted to an adjustable support. …

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Time-Of-Flight Based Sonic Speed Measurements For Cold Gas Thruster Development, Brandon W. Kempf May 2016

Time-Of-Flight Based Sonic Speed Measurements For Cold Gas Thruster Development, Brandon W. Kempf

Mechanical Engineering Undergraduate Honors Theses

The purpose of this thesis is to explore an experiment developed for validating the usage of a gaseous solution of water and propylene glycol for cold gas propulsion. The experiment involves a “Time of Flight” method of calculating the speed of sound in the gas and the corresponding specific heat ratio using a copper tube, two MEMS microphones, a piezoelectric speaker, and data-acquisition hardware. The experiment was calibrated using the known thermodynamic properties of air. The accuracy of the experiment was found to be within 0.6% for calculations of the speed of sound in air and within 1.0% of the …

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Effects Of Noise, Reverberation And Foreign Accent On Native And Non-Native Listeners’ Performance Of English Speech Comprehension, Zhao Ellen Peng, Lily M. Wang May 2016

Effects Of Noise, Reverberation And Foreign Accent On Native And Non-Native Listeners’ Performance Of English Speech Comprehension, Zhao Ellen Peng, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

A large number of non-native English speakers may be found in American classrooms, both as listeners and talkers. Little is known about how this population comprehends speech in realistic adverse acoustical conditions. A study was conducted to investigate the effects of background noise level (BNL), reverberation time (RT), and talker foreign accent on native and non-native listeners' speech comprehension, while controlling for English language abilities. A total of 115 adult listeners completed comprehension tasks under 15 acoustic conditions: three BNLs (RC-30, RC-40, and RC-50) and five RTs (from 0.4 to 1.2 s). Fifty-six listeners were tested with speech from native …

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Design Of Three-Dimensional Near-Zero Refractive Index Metamaterials, David Flores Iii May 2016

Design Of Three-Dimensional Near-Zero Refractive Index Metamaterials, David Flores Iii

Theses and Dissertations

Near-zero refractive index metamaterials exhibit remarkable electromagnetic properties which can and will be applied in the near future. From the known methods of achieving near-zero refractive index, this work primarily focuses on the design of 3D metamaterials whose permittivity and permeability are both close to zero while maintaining relatively low loss factor. The design of the metamaterials is based on the chiral shape “omega” and designed to weave periodically as a fishnet. Theoretical analysis, computer modeling and simulation are steps taken in the design of metamaterials. A computational tool based on the robust method for effective parameter extraction is successfully …

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Design Of A Folding V-Scraper With Roller For Orchard Applications, Chase Ulrich May 2016

Design Of A Folding V-Scraper With Roller For Orchard Applications, Chase Ulrich

BioResource and Agricultural Engineering

This senior project discusses the design of a folding 15 ft. wide leveler for orchard use. This design utilized a category 2 three-point hitch to connect the implement to a tractor. The folding mechanism uses the tractors hydraulic system to actuate the folding movement using hydraulic cylinders. The blades, when wings in operational position, are rigid with one another after some assembly. When the implement is folded the width is reduced to nine feet.

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Design And Optimization Of Membrane-Type Acoustic Metamaterials, Matthew G. Blevins May 2016

Design And Optimization Of Membrane-Type Acoustic Metamaterials, Matthew G. Blevins

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

One of the most common problems in noise control is the attenuation of low frequency noise. Typical solutions require barriers with high density and/or thickness. Membrane-type acoustic metamaterials are a novel type of engineered material capable of high low-frequency transmission loss despite their small thickness and light weight. These materials are ideally suited to applications with strict size and weight limitations such as aircraft, automobiles, and buildings. The transmission loss profile can be manipulated by changing the micro-level substructure, stacking multiple unit cells, or by creating multi-celled arrays. To date, analysis has focused primarily on experimental studies in plane-wave tubes …

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An Evaluation Of Agricultural Tractors Hydraulic Lift Performance, Grant W. Melotz May 2016

An Evaluation Of Agricultural Tractors Hydraulic Lift Performance, Grant W. Melotz

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

The current OECD Code 2 detailing the procedures for the hydraulic lift test of agricultural tractors, section 4.3, published lift values that were sometimes unattainable. The static weight of 2WD, two wheel drive, and MFWD, mechanical front wheel drive, tractors and the amount of lifting force have increased at a greater rate than the amount of static weight on the front axle. This increase in lifting force has led to a decrease in the percent of weight as the upward support force on the front axle of a tractor. Many of the 2WD and MFWD unballasted tractors tested at the …

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Tractor Measurement And Data Acquisition System For Hydraulic Power, Draft Force, And Power Take-Off Torque, James Roeber May 2016

Tractor Measurement And Data Acquisition System For Hydraulic Power, Draft Force, And Power Take-Off Torque, James Roeber

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Numerous advancements in machinery performance of agricultural tractors have been made in recent years. The Organisation for Economic Co-operation and Development (OECD) tests predetermined points (e.g., maximum power and torque) for drawbar, Power Take-Off (PTO), and hydraulic power as separate tests for tractor performance. Testing methods with the tractor operating at a steady state have been done for years, which were uncharacteristic of agricultural tractor operations in field conditions. As part of this thesis work, field usable data acquisition systems (DAQs) were developed to record implement energy consumption (e.g., drawbar loading, PTO torque, and hydraulic power). The system used LabVIEW …

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Polytetraflouroethylene Thin Coatings For Tribological Applications, Samuel L. Jenkins May 2016

Polytetraflouroethylene Thin Coatings For Tribological Applications, Samuel L. Jenkins

Mechanical Engineering Undergraduate Honors Theses

Mechanical components with lower coefficients of friction decrease the amount of energy dissipated by the system due to friction. Coating these components would decrease the coefficients of friction between surfaces without sacrificing the strength of the components. A polytetrafluoroethylene (PTFE) layer adhered through a polydopamine (PDA) layer on a steel substrate will reduce the coefficient of friction on the substrate surface. This paper discusses different methods for attempting to increase the uniformity of the PDA layer as well as decrease the PDA coating time. Methods for increasing uniformity include using a particle disperser instead of a magnet stir rod, changing …

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