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Full-Text Articles in Mechanical Engineering

Orthoplanar Spring Based Compliant Force/Torque Sensor For Robot Force Control, Jerry West Mar 2017

Orthoplanar Spring Based Compliant Force/Torque Sensor For Robot Force Control, Jerry West

Graduate Theses and Dissertations

A compliant force/torque sensor for robot force control has been developed. This thesis presents methods of designing, testing, and implementing the sensor on a robotic system. The sensor uses an orthoplanar spring equipped with Hall-effect sensors to measure one component of force and two moment components. Its unique design allows for simple and cost effective manufacturing, high reliability, and compactness. The device may be used in applications where a robot must control contact forces with its environment, such as in surface cleaning tasks, manipulating doors, and removing threaded fasteners. The compliant design of the sensor improves force control performance ...


Design, Fabrication And Analysis Of A Paver Machine Push Bar Mechanism, Mahendra Palnati Nov 2015

Design, Fabrication And Analysis Of A Paver Machine Push Bar Mechanism, Mahendra Palnati

Graduate Theses and Dissertations

Now-a-days, the major challenge that’s being faced by the concrete industry is the cleaning of concrete handling equipment. Concrete consists of aggregates, which harden with time, and the transportation of concrete mixture within the plant is a significant problem. This will not only increase the overall maintenance cost, but will lead to loss of raw materials, affect the rate of production, and reduce the lifetime of concrete handling equipment.

The present study focuses on the design and implementation of an adaptive cleaning mechanism in the concrete industry and its importance in achieving efficient cleaning, which is tested to verify ...


Shelf-Scale Mapping Of Fish Distribution Using Active And Passive Acoustics, Carrie Christy Wall Jan 2012

Shelf-Scale Mapping Of Fish Distribution Using Active And Passive Acoustics, Carrie Christy Wall

Graduate Theses and Dissertations

Fish sound production has been associated with courtship and spawning behavior. Acoustic recordings of fish sounds can be used to identify distribution and behavior. Passive acoustic monitoring (PAM) can record large amounts of acoustic data in a specific area for days to years. These data can be collected in remote locations under potentially unsafe seas throughout a 24-hour period providing datasets unattainable using observer-based methods. However, the instruments must withstand the caustic ocean environment and be retrieved to obtain the recorded data. This can prove difficult due to the risk of PAMs being lost, stolen or damaged, especially in highly ...


Effects Of Random Cross-Sectioned Distributions, Fiber Misalignment And Interphases In Three-Dimensional Composite Models On Transverse Shear Modulus, Jarrett Zitko Jan 2012

Effects Of Random Cross-Sectioned Distributions, Fiber Misalignment And Interphases In Three-Dimensional Composite Models On Transverse Shear Modulus, Jarrett Zitko

Graduate Theses and Dissertations

Finite element analysis was implemented to evaluate the transverse shear modulus of a unidirectional glass/epoxy fiber-matrix composite based on pure shear displacement boundary conditions. Unit cells consisting of three-dimensional glass cylinders surrounded in square-cuboid epoxy matrices were modeled to represent "Representative Volume Element" (RVE) configurations in periodic and random-periodic square cell arrangements of variable size. Three RVEs were constructed and analyzed: A single unit cell, a 9-cell (3 x 3) array, and a 25-cell (5 x 5) array. Additionally, the unit cell was modeled to include an interphase. Three sets of cell arrangements were constructed and evaluated: a periodic ...


Direct Verification Of The Locking Of Liquid Locking Compounds In Threaded Fasteners, Ryan Hunter Jan 2012

Direct Verification Of The Locking Of Liquid Locking Compounds In Threaded Fasteners, Ryan Hunter

Graduate Theses and Dissertations

The motivation of this research is to explore the viability of a method to directly verify whether or not an anaerobic adhesive within a threaded fastener assembly has cured sufficiently to provide secondary locking. Direct verification was implemented via the application of a test torque in the loosening direction of a fastener assembly with Loctite (given a 24 hour cure time). A three phase test plan was developed with the intent of identifying and utilizing this verification torque value which is unique to a given fastener assembly.

It was proved that the direct verification method, as outlined in the test ...


Design Of Contact Line Friction Measurement Machine Apparatus, Seyed Kamran Najafi Jan 2012

Design Of Contact Line Friction Measurement Machine Apparatus, Seyed Kamran Najafi

Graduate Theses and Dissertations

The purpose of this project is to design and manufacture a high precision machine to directly measure the surface force of fluids. Knowing how to move droplets easier with less resistance can increase the potential of a wide range of applications and improve the performance of things such as self-assembly applications. This machine has the ability to measure forces of up to 100 N with a MEMS based sensor. The motion system on this machine moves a substrate underneath of a droplet for 100 mm and applies dragging force to the sensor. It moves with a controlled speed with high ...


Metal Oxide Graphene Nanocomposites For Organic And Heavy Metal Remediation, Tanvir E. Alam Jan 2012

Metal Oxide Graphene Nanocomposites For Organic And Heavy Metal Remediation, Tanvir E. Alam

Graduate Theses and Dissertations

This thesis consists of two research problems in the water decontamination area. In the first work, the main focus is to understand the structure and photocatalytic activity of titanium dioxide with graphene (G-TiO2) which is synthesized by using sol-gel method. The photocatalytic activity of TiO2 is limited by the short electron hole pair recombination time. Graphene, with high specific surface area and unique electronic properties, can be used as a good support for TiO2 to enhance the photocatalytic activity. The obtained G-TiO2 photocatalysts has been characterized by X-Ray Diffraction (XRD), Raman Spectroscopy, Transmission Electron Microscopy (TEM), FTIR Spectroscopy and Ultraviolet ...


A Statically Balanced Shape-Shifting Surface, Joseph Eugene Pishnery Jan 2012

A Statically Balanced Shape-Shifting Surface, Joseph Eugene Pishnery

Graduate Theses and Dissertations

ABSTRACT

This paper presents a concept for producing a Statically Balanced Shape-Shifting Surface (SB-SSS). In this context, an SB-SSS is a surface that can require near-zero magnitude force changes to accomplish a change in shape while retaining effectiveness as a physical barrier. This paper focuses on how to statically balance a specifically-designed compliant mechanism and how to incorporate this mechanism into a polygonal cell.

The mechanism consists of a compliant Peaucellier-Lipkin linkage layered with a pre-stressed link as the balancer. Previous work is presented that can show how a polygonal cell can be incorporated into a surface via a tiling ...


Human Motion Tracking For Assisting Balance Training And Control Of A Humanoid Robot, Ahmad Adli Manasrah Jan 2012

Human Motion Tracking For Assisting Balance Training And Control Of A Humanoid Robot, Ahmad Adli Manasrah

Graduate Theses and Dissertations

Abstract

This project illustrates the use of the human's ability to balance according to his center of gravity as demonstrated in two applications. The center of gravity of a human is explained in detail in order to use it in controlling the Aldebaran NAO robot and in the robot-assisted balance training.

The first application explains how a humanoid robot can mimic a human's movements via a three dimensional depth sensor where the sensor analyzes the position of a user's limbs and how the robot can lift one foot and balance on the other by redistributing the its ...


A Novel Ultrasonic Method To Quantify Bolt Tension, Jairo Andres Martinez Garcia Jan 2012

A Novel Ultrasonic Method To Quantify Bolt Tension, Jairo Andres Martinez Garcia

Graduate Theses and Dissertations

The threaded fasteners are one of the most versatile methods for assembly of structural components. For example, in bridges large bolts are used to fix base columns and small bolts are used to support access ladders. Naturally not all bolts are critical for the operation of the structure. Fasteners loaded with small forces and present in large quantities do not receive the same treatment as the critical bolts. Typical maintenance operations such tension measurements, internal stress checking or monitoring of crack development are not practical due to cost and time constrains. Although failure of a single non-critical fastener is not ...


Multistable Shape-Shifting Surfaces (Mssss), Paul Joseph Montalbano Jan 2012

Multistable Shape-Shifting Surfaces (Mssss), Paul Joseph Montalbano

Graduate Theses and Dissertations

This paper presents designs for Multistable Shape-Shifting Surfaces (MSSS) by introducing bistability into the Shape-Shifting Surface (SSS). SSSs are defined as surfaces that retain their effectiveness as a physical barrier while undergoing changes in shape. The addition of bistability to the SSS gives the surface multiple distinct positions in which it remains when shifted to, i.e. by designing bistability into a single SSS link, the SSS unit cell can change into multiple shapes, and stabilize within the resulting shape, while maintaining integrity against various forms of external assaults normal to its surface. Planar stable configurations of the unit cell ...


Design And Testing Of A Motion Controlled Gait Enhancing Mobile Shoe (Gems) For Rehabilitation, Ismet Handzic Jan 2011

Design And Testing Of A Motion Controlled Gait Enhancing Mobile Shoe (Gems) For Rehabilitation, Ismet Handzic

Graduate Theses and Dissertations

Persons suffering central nervous system damage, such as a stroke, coma patients, or individuals that have suffered damage to the spinal cord, brainstem, cerebellum, and motor cortex, sometimes develop an asymmetric walking pattern where one leg does not fully swing backward. This uneven gait hinders these individuals in properly and efficiently moving through everyday life.

Previous research in humans and various animals has introduced a split belt treadmill to analyze possible rehabilitation, which can recreate a correct gait pattern by altering the speed of each track. Gait adaptation was achieved by having the split belt treadmill move each leg at ...


Minimal And Symmetric Global Partition Polynomials For Reproducing Kernel Elements, Mario Jesus Juha Jan 2011

Minimal And Symmetric Global Partition Polynomials For Reproducing Kernel Elements, Mario Jesus Juha

Graduate Theses and Dissertations

The Reproducing Kernel Element Method is a numerical technique that combines finite element and meshless methods to construct shape functions of arbitrary order and continuity, yet retains the Kronecker-d property. Central to constructing these shape functions is the construction of global partition polynomials on an element. This dissertation shows that asymmetric interpolations may arise due to such things as changes in the local to global

node numbering and that may adversely affect the interpolation capability of the method. This issue arises due to the use in previous formulations of incomplete polynomials that are subsequently non-affine invariant. This dissertation lays out ...


Analyses Of Variable Refrigerant Flow And Exergy In Air Conditioning Systems, Rashid Ali Alshatti Jan 2011

Analyses Of Variable Refrigerant Flow And Exergy In Air Conditioning Systems, Rashid Ali Alshatti

Graduate Theses and Dissertations

This thesis consists of two research problems in the air conditioning (A/C) area. For the first problem, the aim is to model and simulate a variable refrigerant flow (VRF) air conditioning system. The coefficient of performance (COP) for refrigeration or heat pump system is one of the critical parameters for designing an air conditioning system. The modeling of the system components for a VRF cycle under different cooling conditions using R-134a and R-22 as refrigerants was carried out. Calculations were performed by varying different parameters such as condenser and evaporator temperatures, and refrigerant type. The R-134a refrigerant shows a ...


A Remotely Operated Multi-Tracked Vehicle For Subterranean Exploration Of Gopher Tortoise Burrows, William Keese Jan 2011

A Remotely Operated Multi-Tracked Vehicle For Subterranean Exploration Of Gopher Tortoise Burrows, William Keese

Graduate Theses and Dissertations

The gopher tortoise is a land tortoise living in the southeastern United States. It is a species in decline and is listed as threatened or endangered in six different states. The gopher (as commonly referred) digs burrows that it uses for many reasons and spends most of its time underground. Problems occur when trying to estimate a population because a gopher tortoise digs more than one burrow. This thesis demonstrates an innovative way to survey and investigate a gopher tortoise burrow hole by using a multi-tracked remotely operated vehicle. The vehicle carried two cameras (fore and aft) and was equipped ...


Modeling Of Solar-Powered Single-Effect Absorption Cooling System And Supermarket Refrigeration/Hvac System, Ammar Bahman Jan 2011

Modeling Of Solar-Powered Single-Effect Absorption Cooling System And Supermarket Refrigeration/Hvac System, Ammar Bahman

Graduate Theses and Dissertations

This thesis consists of two different research problems. In the first one, the aim is to model and simulate a solar-powered, single-effect, absorption refrigeration system using a flat-plate solar collector and LiBr-H2O mixture as the working fluid. The cooling capacity and the coefficient of performance of the system are analyzed by varying all independent parameters, namely: evaporator pressure, condenser pressure, mass flow rate, LiBr concentration, and inlet generator temperature. The cooling performance of the system is compared with conventional vapor-compression systems for different refrigerants (R-134a, R-32, and R-22). The cooling performance is also assessed for a typical year ...


Theoretical And Experimental Analysis Of Power And Cooling Cogeneration Utilizing Low Temperature Heat Sources, Gökmen Demirkaya Jan 2011

Theoretical And Experimental Analysis Of Power And Cooling Cogeneration Utilizing Low Temperature Heat Sources, Gökmen Demirkaya

Graduate Theses and Dissertations

Development of innovative thermodynamic cycles is important for the efficient utilization of low-temperature heat sources such as solar, geothermal, and waste heat sources. Binary mixtures exhibit variable boiling temperatures during the boiling process, which leads to a good thermal match between the heating fluid and working fluid for efficient heat source utilization. This study presents a theoretical and an experimental analysis of a combined power/cooling cycle, which combines the Rankine and absorption refrigeration cycles, uses ammonia-water mixture as the working fluid and produces power and refrigeration, while power is the primary goal. This cycle, also known as the Goswami ...


Physically Meaningful Harmonization Of Tire/Pavement Friction Measurement Devices, Madhura Priyanga Nishshanke Rajapakshe Jan 2011

Physically Meaningful Harmonization Of Tire/Pavement Friction Measurement Devices, Madhura Priyanga Nishshanke Rajapakshe

Graduate Theses and Dissertations

Accurate characterization and evaluation of tire/pavement friction is critical in assuring runway and highway safety. Historically, Pavement Friction Measurement Devices (PFMDs) employing different measuring mechanisms have been used to evaluate tire/pavement friction. They yield significantly disparate friction coefficients under the same contact conditions. Currently, an empirically developed data harmonization method based on a reference device (Dynamic Friction Tester (DFT)) is used in an attempt to overcome the disparities between the measurements using various different PFMDs. However, this method, which has been standardized by the American Society for Testing and Materials (ASTM E1960), has been criticized for its inconsistency ...


Energy Recovery Devices In Seawater Reverse Osmosis Desalination Plants With Emphasis On Efficiency And Economical Analysis Of Isobaric Versus Centrifugal Devices, Mageed Jean Guirguis Jan 2011

Energy Recovery Devices In Seawater Reverse Osmosis Desalination Plants With Emphasis On Efficiency And Economical Analysis Of Isobaric Versus Centrifugal Devices, Mageed Jean Guirguis

Graduate Theses and Dissertations

With huge demands for potable water in regions lacking fresh water sources such as surface or ground water, various potential technologies have been explored for eliminating water shortage. Seawater emerged as a potential source and a major lifeline for such water-deprived areas. The development of seawater reverse osmosis (SWRO) technology proved to be a groundbreaking innovation, making it easier to extract pure water from seawater. Ever since its inception, SWRO technology has taken many leaps towards the development of energy efficient and high yielding systems. The reduction in energy consumption of desalination plants that were based on the SWRO technology ...


Thermophysical Characterization Of Nanofluids Through Molecular Dynamic Simulations, John Shelton Jan 2011

Thermophysical Characterization Of Nanofluids Through Molecular Dynamic Simulations, John Shelton

Graduate Theses and Dissertations

Using equilibrium molecular dynamics simulations, an analysis of the key thermophysical properties critical to heat transfer processes is performed. Replication of thermal conductivity and shear viscosity observations found in experimental investigations were performed using a theoretical nanopthesis-fluid system and a novel colloid-fluid interaction potential to investigate the key nanofluid parameters. Analysis of both the heat current (thermal conductivity) and stress (shear viscosity) autocorrelation functions have suggested that the dominant physical mechanisms for thermal and momentum transport arises from enhancements to the longitudinal and transverse acoustic modes energy transfer brought about by the increased mass ratio of the nanopthesis to the ...


Thermal Response Of Lithium Tantalate For Temperature Measurement, Ardit Agastra Jan 2011

Thermal Response Of Lithium Tantalate For Temperature Measurement, Ardit Agastra

Graduate Theses and Dissertations

This thesis describes the study of the thermal response of the pyroelectric material named lithium tantalate or LT (LiTaO3) in aid of this material's possible use for temperature measurement. The temperature range studied was between 5-99oC. The sensor was excited using a silicon rubber heater. The lithium tantalate sensor and the rubber heater were enclosed such that the temperature would reach steady state faster. The enclosure was a small insulated box in order to reduce any extraneous effects on the sensor. The output signal of the lithium tantalate sensor was then amplified by using four different amplifying circuits and ...


Thermo-Mechanical Beam Element For Analyzing Stresses In Functionally Graded Materials, Simon Caraballo Jan 2011

Thermo-Mechanical Beam Element For Analyzing Stresses In Functionally Graded Materials, Simon Caraballo

Graduate Theses and Dissertations

Modeling at the structural scale most often requires the use of beam and shell elements. This simplification reduces modeling complexity and computation requirements but sacrifices the accuracy of through-the-thickness information. Several studies have reported various design approaches for analyzing functionally graded material structures. One of these studies proposed a two-node beam element for functionally graded materials (FGMs) based on first order shear deformable (FOSD) theory. The derivation of governing equations included spatial temperature variation. However, only the constant temperature case was carried through in the element formulation. This investigation explore the effects of spatial temperature variation in the axial and ...


Numerical Simulations Of Heat Transfer Processes In A Dehumidifying Wavy Fin And A Confined Liquid Jet Impingement On Various Surfaces, Mutasim Mohamed Sarour Elsheikh Jan 2011

Numerical Simulations Of Heat Transfer Processes In A Dehumidifying Wavy Fin And A Confined Liquid Jet Impingement On Various Surfaces, Mutasim Mohamed Sarour Elsheikh

Graduate Theses and Dissertations

This thesis consists of two different research problems. In the first one, the heat transfer characteristic of wavy fin assembly with dehumidification is carried out. In general, fin tube heat exchangers are employed in a wide variety of engineering applications, such as cooling coils for air conditioning, air pre-heaters in power plants and for heat dissipation from engine coolants in automobile radiators. In these heat exchangers, a heat transfer fluid such as water, oil, or refrigerant, flows through a parallel tube bank, while a second heat transfer fluid, such as air, is directed across the tubes. Since the principal resistance ...


Interface Engineered Diamond Coatings For Dry Machining Applications, Humberto Arturo Gomez Vega Jan 2011

Interface Engineered Diamond Coatings For Dry Machining Applications, Humberto Arturo Gomez Vega

Graduate Theses and Dissertations

Several studies have been propose to improve the adhesion of diamond films on cemented carbide tool materials, however a systematic study in identifying the role of the factors that affect the final diamond adhesion and the resulting machining performance of the tool under real manufacturing conditions is still unexplored. CVD diamond film's extraordinary qualities bring little benefit if the film fails to adhere sufficiently to the substrate. Inadequate adhesion undermines tool performance and longevity, causing unpredictable behavior under load and possibly leading to unexpected failure of the tool in the production line. This dissertation investigates the effects of different ...


Utilizing A Computational Model For The Design Of A Passive Dynamic Walker, Craig Alan Honeycutt Jan 2011

Utilizing A Computational Model For The Design Of A Passive Dynamic Walker, Craig Alan Honeycutt

Graduate Theses and Dissertations

Recent interest in using passive dynamic walkers (PDWs) for gait rehabilitation studies has presented a need for a robust, easily built mechanism. Unfortunately, these passive robots are hypersensitive to many variables outside of the usual design considerations that are studied when constructing them. By accentuating previous failures instead of suppressing them, this thesis presents a number of problematic situations commonly experienced when testing and tuning a PDW.

Further, through a complete design of a 4-legged PDW with knees, simple design axioms brought about by myself and others are put into a practical context and applied directly to design. This thesis ...


Diamond Based-Materials: Synthesis, Characterization And Applications, Qiang Hu Jan 2011

Diamond Based-Materials: Synthesis, Characterization And Applications, Qiang Hu

Graduate Theses and Dissertations

The studies covered in this dissertation concentrate on the various forms of diamond films synthesized by chemical vapor deposition (CVD) method, including microwave CVD and hot filament CVD. According to crystallinity and grain size, a variety of diamond forms primarily including microcrystalline (most commonly referred to as polycrystalline) and nanocrystalline diamond films, diamond-like carbon (DLC) films were successfully synthesized. The as-grown diamond films were optimized by changing deposition pressure, volume of reactant gas hydrogen (H2) and carrier gas argon (Ar) in order to get high-quality diamond films with a smooth surface, low roughness, preferred growth orientation and high sp3 bond ...


Polydimethylsiloxane Mechanical Properties Measured By Macroscopic Compression And Nanoindentation Techniques, Zhixin Wang Jan 2011

Polydimethylsiloxane Mechanical Properties Measured By Macroscopic Compression And Nanoindentation Techniques, Zhixin Wang

Graduate Theses and Dissertations

In this thesis, the relationship between the elastic modulus of PDMS and the base/agent ratio (the amount of crosslinking) is studied. Reliable macroscopic compression test instrument was developed. Preload method was applied for the nanoindentation flat punch test to develop full contact.

In chapter 2, an easy instrument setup for macroscopic compression test is described. A series of PDMS samples with different base/agent ratios were tested using the macroscopic compression method. The relationship between PDMS elastic modulus and its base/agent ratio was established.

In chapter 3, PDMS nanoindentation DMA tests provide stable data with different test control ...


Modeling And Parameter Study Of Bistable Spherical Compliant Mechanisms, Chester Smith Jan 2011

Modeling And Parameter Study Of Bistable Spherical Compliant Mechanisms, Chester Smith

Graduate Theses and Dissertations

The bistable spherical compliant mechanism (BSCM) is a novel device capable of large, repeatable, out-of-plane motion, characteristics that are somewhat difficult to achieve with surface micromachined microelectromechanical systems. An improved pseudo-rigid-body model (PRBM) to predict the behavior of the BSCM is presented. The new model was used to analyze seven different versions of the device, each with a different compliant joint length. The new model, which adds torsion, is compared with a finite element analysis (FEA) beam model. The new model more closely approximates the results yielded by FEA than previous models used to analyze the BSCM. Future work is ...


Design And Analysis Of An Innovative Semi-Flexible Hybrid Personal-Body-Armor System, Daniel Jeffrey Miller Jan 2011

Design And Analysis Of An Innovative Semi-Flexible Hybrid Personal-Body-Armor System, Daniel Jeffrey Miller

Graduate Theses and Dissertations

Current military-grade rifle body armor technology uses hard ballistic plates positioned on top of flexible materials, such as woven Kevlar® to stop projectiles and absorb the energy of the impact. However, absorbing the impact energy and stopping a rifle projectile comes at a cost to the wearer - mobility. In this thesis, a new concept for personal body armor is proposed - a semi-flexible hybrid body armor. This hybrid armor is comprised of two components that work as a system to effectively balance the flexibility offered by a soft fabric based armor with the protection level of hard plated armor. This work ...


Self-Alignment Of Silicon Microparts On A Hexadecane-Water Interface By Surface Tension, Caroline Elizabeth Liberti Jan 2011

Self-Alignment Of Silicon Microparts On A Hexadecane-Water Interface By Surface Tension, Caroline Elizabeth Liberti

Graduate Theses and Dissertations

Mechanical assembly of systems and structures on the micro-scale can be inefficient as pthesiss of sub-millimeter dimensions are difficult to manipulate. Cutting edge manufacturing methods implement self-assembly as an approach to ordering micro and nano-sized parts into a desired arrangement. This thesis studies a technique utilizing surface tension as a method of actuating microparts on a liquid-liquid interface via lateral capillary interactions. Preliminary experimentation is conducted to investigate the feasibility of developing a new method for self-alignment of microparts by observing the influence of interfacial geometry on the movement of silicon tiles along a hexadecane-water interface. Different surface geometries are ...