bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic Emission Analysis of Defective Radial Ball Bearings for Quality Control
Authors: Oliver Corey , Lin Lin
Published: January 2018

The objective of this study is to capture and characterize the acoustic emissions of radial ball bearings in operation. A comparison is made between healthy bearings and defective ones. A precise 0.012” wide groove was cut into either a ball, the inner or outer race of test bearings. To reduce vibrational interference, the test shaft is isolated using a magnetic coupling and is supported by a thrust air bearing. The test bearing is acoustically insulated from its surrounding with mass loaded vinyl and acoustic reflections are dampened by wedge foam to improve the signal quality. The acoustic emissions are captured and digitized using a smartphone. Various signal processing techniques are used to characterize the signals and analyze defect modes. The results provide a comparison between the acoustic emissions of healthy and defective bearings operated at various speeds and provide methods for characterization.
Review and Analysis of Repair/Rehabilitation Methods for Natural Gas Pipelines
Authors: Sanchez Abraham , Ojeda Marianella , Gomez Humberto , Bermejo Carlos , Medina Victor , Escorcia Orlando , Bris Jorge , Morelo Alvaro , Maury Heriberto , Medina Julio
Published: January 2018

The integrity of pipelines during the transportation of flammable fluids requires the development or implementation of repair/rehabilitation techniques that ensure their performance over time in a cost-effective way, due to the high and potential costs that result from failure (loss of life, damage to property, and penalties from service interruption). In this work, a review of the typical defectology found in gas transport steel pipeline systems is described. As part of the review, the current status of technologies and techniques implemented for the repair and rehabilitation of pipes in the Oil & Gas industry is presented. Based upon the available solutions, a revision is proposed from the regulations and standards which define the implementation of these type of solutions for the natural gas transport pipelines. A comparative summary that includes mechanized or induced defects on pipes for further study and performance measurement of the implemented solutions is presented. Decision factors to be considered in the selection process are displayed according to a particular gas transportation operator’s requirements and general criteria. These factors take into account the required considerations with respect to the pipe material, effect on environments, skill requirements for installation, the in-service installation capability, and the final selected method.
Performance Assessment of a Cooling Tower and a Ground Source Heat Pump for Heat Dissipation
Authors: Moreira Daniel , Zabala Gonzalo , Villanueva Rubén , Soriano Guillermo
Published: January 2018

An experimental comparison between two heat sinks systems has been performed. The area of the study is Guayaquil, Ecuador with an average annual temperature of 27 °C and an average annual relative humidity of 77% (UTM 0621517/09749485) where typical large HVAC systems with cooling towers are used. As a result of the high relative humidity in the area, the thermal efficiency of this type of heat exchanger is reduced. A geothermal heat exchanger cooling water using the constant and relatively low soil temperature is considered as a viable alternative for HVAC systems in this location. In this project, a prototype geothermal heat exchanger is built and experimentally compared with a cooling tower system.

Through previous research, it was determined that the soil at this borehole consist of 5 % of landfill material; 86 % several strata of low plasticity silt, alternating silt; and 5 % sand. This location corresponds to the estuarine deposits of the Guayas River. The average soil temperature is 27 ° C, associated with a thermal conductivity of 1.87 W / m K and a thermal diffusivity of 0.085 m2 / day obtained from a Thermal Response Test of the soil.

An experiment for the comparison of these two types of heat exchangers under a uniform heat load is designed and built. The cooling tower water installed has a capacity of 5 Tons of Refrigeration with a flow of 15 Gallons per minute. The geothermal heat exchanger consisting of four drilled to 42 meters deep vertical holes and connected in a parallel circuit. Both systems operate in periods of 8 and 12 hours during the hours of daylight. To simulate the thermal load in both cases, water is heated using two identical electric boilers with a nominal power of 9 kW each. Data from the energy consumption, and energy dissipation from each system is collected and analyzed.

The Energy Efficiency Rating obtained for each system is on the order of 10.61 for the cooling tower water, and on the order of 14.78 for the geothermal heat exchanger, with savings of 61.7% in energy consumption and CO2 emissions by the system of geothermal cooling through better efficiency.

We have also projected the costs of installation, operation and maintenance of both systems. Results suggest that despite the high cost of installation, a geothermal sink is a valid option for HVAC systems in cities or regions that have high temperatures and high humidity.
Experimental Study of Thermal Energy Storage Using Natural Porous Media
Authors: Al Edhari A. J. , Ngo C. C.
Published: January 2018

Thermal energy storage has been an area of research interest due to the need to store solar energy or excess energy for later use in many applications including district heating. The focus of a lot of research is on exotic and expensive storage media. This paper presents an experimental study of thermal energy storage using porous media readily available and commonly found in nature such as sand, soil, pebble rocks and gravel. This study also considers a simple and inexpensive thermal storage system which could be constructed easily and examines what could be done to increase the thermal storage performance. The thermal storage system examined in the present study was a thermal energy storage unit with embedded horizontal pipes carrying water as the heat transfer fluid for thermal charging. Different thermal storage configurations were examined by adjusting the thermal charging temperature and using different storage media. The temperature distribution within the storage media was monitored for 10 hours using a data acquisition system with K-type thermocouples. The results indicate that a thermal storage system using sand as storage media is slightly better compared with gravel or pebble rocks as storage media.
Design of Wearable Rings for Vibratory Haptic Feedback
Authors: Lin Jianping , Park Wooram
Published: January 2018

In tele-operation, the haptic technology provides users with the sense of touch with which they can remotely control the slave side more effectively. Delivering the force reaction in the slave side to the user in the master side becomes a challenging component in this framework, because this force transfer requires reliable sensing, stable force display, and associated signal processing. Vibrations can be used in haptic devices where the direct force sensing and transfer are difficult. In this research, we develop a theoretic design scheme for a small-size wearable ring which vibrates to give the haptic feedback to the user. This device uses the resonant vibration of a permanent magnet in the vibrating electromagnetic field. A magnet and soft material support form a mass-spring-damper system. This paper concerns the design problem to optimize the vibration response of this mass-spring-damper system. We develop a design method for the geometric shapes of the soft material to achieve maximum vibration performance. We accomplish the optimization using force transmissibility, and found that it is a better objective function than displacement transmissibility.
Computation of Lyapunov Characteristic Exponents Using Parallel Computing
Authors: von Bremen Hubertus F. , Bonilla Michael J.
Published: January 2018

In [1] a method to accurately compute the Lyapunov Characteristic Exponents of continuous dynamical systems of arbitrary dimensions was presented. However, it can be computationally expensive, because it requires the computation of the time derivatives of the entries of the exponential of a skew-symmetric matrix. In this paper, we present an implementation of the method in [1] that takes advantage of the fact that some of the computations can be done in parallel. The speedup in the computations depends on the number of CPU cores used and the computer memory. Numerical simulations show improvements in efficiency when using the parallel implementation. Our implementation retains the accuracy of the method in [1] with the added advantage of a speedup in computations. Numerical simulation results are presented for a dynamical system of dimension seven and one of dimension forty-nine.
Mechanical Modeling of Fractal Interlocking
Authors: Monsef Khoshhesab Mona , Li Yaning
Published: January 2018

Topological interlocking is an effective joining approach in both natural and engineering systems. Especially, hierarchical/fractal interlocking are found in many biological systems and can significantly enhance the system mechanical properties. Inspired by the hierarchical/ fractal topology in nature, mechanical models for Koch fractal interlocking were developed as an example system to better understand the mechanics of fractal interlocking. In this investigation, Koch fractal interlocking with different number of iterations N were designed. Theoretical contact mechanics model was used to analytically capture the mechanical behavior of the fractal interlocking. Then finite element (FE) simulations were performed to study the deformation mechanism of fractal interlocking under finite deformation. It was found that by increasing the number of iterations, the contact area increases and the interlocking stiffness and strength also significantly increase. The friction coefficient of contact plays an important role in determining the mechanical properties of fractal interlocking.
Numerical Study of Natural Convection Heat Transfer Over a Cooling Stage
Authors: Haque Mohammad Rejaul , Betz Amy Rachel
Published: January 2018

Numerical study of natural convection phenomenon close to a cooling stage has been investigated in a two dimensionally controlled environment. The study was conducted for ambient air which was kept at constant temperature (22°C) and Prandtl number of this Newtonian fluid was taken as 0.71. The cooling stage was kept at 5°C and height of the stage was considered 0.02 m. The stage was located at the bottom on the computational domain. The center of cooling stage was placed at X = 0.35 m and X = 0.5 m respectively from the left boundary of the domain. Later, computational analysis was performed to solve coupled momentum and energy equations for appropriate boundary conditions. The study was performed for a range of Rayleigh number from 102 to 107. Thermal and hydrodynamic behavior was reported in terms of isotherms, streamlines and average Nusselt number calculation. The position of the stage significantly effects heat transfer and flow fields. Nusselt number was evaluated close to cooling stage. Streamlines resulted huge recirculation region which was symmetric about the vertical mid-centerline of the domain for cooling stage located at X = 0.5 m. The center of core vortices shifted near to the cooling stage as Rayleigh number increases ensuring enhancement of heat transfer. Additionally, increasing Rayleigh number induces significant buoyancy driven flow. The velocity of this driven flow increases towards left and right wall as Rayleigh number increases. Velocity profile was also evaluated due to flow inside the enclosure. A parabolic variation was observed for horizontal velocity component near the isothermal walls and it was found less significant compared to vertical component due to buoyancy driven flow. Moreover, the asymmetric distribution of isotherms created by eccentric position of the stage resulted better enhancement than centric position of the cooling stage. Finally, this results would help the researchers find the optimal position of any sample on a cooling stage subjected to convection phenomenon. This could be significant in the collection of experimental data for condensation and frost formation.
Organization and Compaction of Composite Filler Material Using Acoustic Focusing
Authors: Chai Lauren A. , Anthony Brian W.
Published: January 2018

Carbon nanofibers in polymer-based composites reduce the electrical resistivity of the composite but can be up to 100 times more expensive than the bulk polymer. This work uses acoustic focusing to organize and compact carbon nanofibers in a mineral oil mixture. The result is a decrease in the composite electrical resistivity without an increase in the global volume fraction of the fibers in the composite and associated material cost.

The composite consisted of Pyrograf PR-19-LHT carbon nanofibers mixed in light mineral oil at 1.6% volume fraction carbon nanofibers. The mixture was contained in a 1 cm × 1 cm × 4 cm glass cuvette. A PZT-4 piezoelectric transducer, epoxied to the external face of one of the sidewalls, generated the acoustic radiation forces in the container. A 1.179 MHz sinusoidal signal powered the transducer, producing a standing wave with 27 nodes and 13 antinodes in the container. A digital multimeter performed the 2-wire resistance measurement before, during and after focusing.

Settling of the filler due to gravity resulted in an initial drop in the electrical resistance. Once the mixture reached steady state, toggling the signal power off and on also toggled the approximate electrical resistance between the 19.2 MOhms and 11.5 MOhms respectively. This work also presents a simple volume fraction model, which predicted that the focused resistance would be 34% of the unfocused value. In the experiment, acoustic focusing reduced the electrical resistance to 60% of the resistance in the unfocused mixture, demonstrating acoustic focusing as a method for reducing electrical conductivity within a composite.
Investigation of Thermal and Energy Performance of Green Roofs in Florida Climate
Authors: Sangal Dhruv , Najafi Hamidreza
Published: January 2018

Buildings are responsible for approximately 40% of energy consumption in the United States. Utilizing efficient methods for reduction in energy consumption by buildings is of great importance. Green roofs have been known as an effective approach to reduce building energy usage (associated with cooling and heating load) as well as providing environmental benefits. In the present paper, a mathematical model is developed in MATLAB considering several aspects of green roofs. The model is validated using available data from previous experimental research studies. A simulation is conducted to assess the performance of green roofs in Melbourne, FL. The study includes calculation of the energy savings associated with using a green roof in summer months and winter months.
A Reactivity Study of Jet Fuel Relevant Pure Hydrocarbon Components in a Rapid Compression Machine
Authors: Min Kyungwook , Valco Daniel , Oldani Anna , Lee Tonghun
Published: January 2018

Autoignition behavior of jet fuel relevant pure hydrocarbon components have been investigated using a rapid compression machine and validated with chemical kinetics simulations. Employment of alternative energy sources can alleviate the energy crisis that this generation confronts. Alternative fuels can be obtained from diverse feedstocks through a variety of pathways. Due to this diversity, numerous alternative fuels have unique compositions which are distinct from conventional fuels. Evaluating differences in combustion behavior of these fuels is a pivotal and initial task of drop-in fuel applications. Hydrocarbon species in conventional and alternative fuels can be broadly classified into four major groups: normal alkanes, isoalkanes, cyclic alkanes, and aromatics. The focus of this study are normal and isoalkanes, where three isomers of dodecane have been selected and tested to evaluate the contribution of chemical structure in autoignition behavior. N-dodecane, which is a straight chain of twelve carbons, and two isododecanes with different degrees of branching are tested in heated rapid compression machine (RCM) at University of Illinois, Urbana-Champaign. Measurements were made at compressed pressures (Pc) of 10 and 20 bar, with fuel and oxidizer (dry air) mixture of equivalence ratio (ϕ) at unity, 0.5 and 0.25. Compressed temperatures (Tc) of the tests are in low to intermediate range (620 K < T < 710 K) where NTC behavior has been observed for heavily branched isododecane. The direct test chamber method is used for precise and reliable measurements. Ignition delay times of n-dodecane are the shortest among tested fuels, as expected. Extremely low reactivity of the pentamethylheptane, heavily branched isododecane has been observed. The results have also compared to JP-8 as a reference. For several conditions where first and second stage ignition are distinguishable, it is shown that temperature dependency is greater for first stage ignition delay than second stage.
Modelling and Validation of a Hybrid Trigeneration/Photovoltaic System Installed in a Shopping Mall Complex
Authors: López Vega Aldo , Kowalski Gregory J. , Rubio-Maya Carlos , Pacheco Ibarra J. Jesús
Published: January 2018

Shopping malls require large amount of electrical and thermal energy to provide quality services and maintain customer’s comfort. Conventionally, electrical energy for direct use and operation of HVAC systems is supplied directly from the electrical grid and is produced in remote power plants that burns fossil fuels. Thermal energy for hot water or heating supply is usually produced by boilers that use LP gas or fuel oil. Given these conditions, cogeneration and trigeneration systems supported by renewable sources of energy are ideal schemes to meet energy needing in a more efficient and cost-effective manner. For this reason, a hybrid trigeneration/photovoltaic system has been installed to cover approximately 50% of the electrical and thermal demands of a shopping mall complex, located in Morelia (MichoacÁn, Mexico). The trigeneration plant consists of a microturbine with an electric power output of 65 kW, three absorption chillers with an output of 5 RT each and a photovoltaic system of 30 kW of electrical power, composed of 108 photovoltaic modules of 280 W each. The Incentive Program for Technology Innovation of the National Council of Science and Technology has funded and sponsored the project and it is to demonstrate on-site feasibility under the Mexican energy context. The installation will generate information on the global and specific operation of the components. In this paper, the development and validation of thermodynamic models to analyze and simulate the individual and integral operation of the hybrid trigeneration/photovoltaic system components is presented. These models based on the First and Second law will allow an integral simulation of the plant to determine the most appropriate operating conditions. The First and Second law efficiencies as well as the exergy destruction in each component is reported. The models have been developed from data provided by manufacturers and the application of mass, energy and exergy balances. The validation of models has been carried out using experimental data acquired directly from the components of the plant and other measurement instruments that have been used for this purpose. The results of the models have been compared with experimental data and have showed satisfactory agreement, with an average difference of 2.92%.
Numerical Simulation of an Injection Microscale Calorimeter to Identify Significant Thermal Processes and Verify Data Reduction Procedures
Authors: Modaresifar Masoud , Kowalski Gregory J.
Published: January 2018

A numerical solution based on a varying node volume for the mass diffusion, thermal response during a dilution experiment of a reacting mixture was performed. The unique feature of the solution was its use of partial volumes and incorporating the changes in heat transfer area and internal node volume changes. The limiting behavior of these transient responses was in agreement with expected analytical results. The resulting temperature and concentration responses were used with a typical EOT calibration relation to estimate its response during an experiment. The calculated EOT and temperature time response exhibit the same trends as that observed experimentally.
Experimental Modal Analysis of a Fixed-Fixed Beam Under Axial Force
Authors: Hassanpour Pezhman A. , Alghemlas Khaled , Betancourt Adam
Published: January 2018

In this paper, an experimental procedure is proposed for determining the resonance frequencies and mode shapes of vibration of a fixed-fixed beam. Since it is fixed at both ends, the beam may sustain an axial force due to several factors including the fasteners and/or change of temperature. The analytical governing equations of motion, frequency equation, and mode shapes of vibration are presented. The analytical model is used to justify the experimental approach as well as interpretation of the experiment data. In this study, a hammer is used to excite the beam, and then the vibration of the beam is observed and recorded at two different points on the beam using two laser Doppler vibrometers. The data from the vibrometers are used to extract the resonance frequencies and mode shapes of vibrations. Using the analytical model, the axial force in the beam is estimated.
Mixed Sensitivity Design of PID Controller-Applied to a Ball and Beam System
Authors: Emami Tooran
Published: January 2018

This paper presents a set of algorithm for all achievable coefficients of Proportional Integral Derivative (PID) controllers that stabilize the system and satisfy a mixed sensitivity constraint with an uncertain time delay. Additive uncertainty modeling is used to describe the uncertainty of perturbed system. Additive uncertainty modeling performs much faster response with the time running of computer programming in MATLAB. This technique is applied to a ball and beam system transfer function with the assumption of uncertain communication time delays in the system process. The goal of this application is to regulate a ball position on a beam and also satisfy the mixed sensitivity constraint.
Modal Analysis and Experimental Testing of Air-Inflated Drop-Stitch Fabric Structures Used in Marine Applications
Authors: Hulton Andrew W. , Cavallaro Paul V. , Hart Christopher J.
Published: January 2018

Rapid deployment of marine structures is of growing importance to U.S. naval forces. Surface-based inflatable structures including Rigid Inflatable Boats (RIBs), inflatable causeways and bridging, and launch and recovery systems provide unique solutions for temporary structures during sea-based missions. When performance specifications demand minimal weight and stowage, rapid deployability and temporary rigidity, solutions are limited to inflatable structures constructed of flexible materials. Driven by air pressure, today’s inflatables provide significant load-carrying capacities per unit weight (or stowed volume) utilizing technical textiles, elastomers or “soft” composites. Overloading of inflatable structures produces unique fail-safe behaviors (reversible wrinkling) that allow the structures to assume rigidity and load-carrying capacity upon load removal.

Design standards are virtually nonexistent for inflatable structures involving shapes constructed of spheres, beams, arches and most recently flat panels using 3D woven drop-stitch panels. Predictive performance tools (analytical and numerical) for static applications lag significantly behind those for conventional structures. Nonlinear system behaviors (material and geometric), thermo-mechanical coupling and fluid-structure interactions (FSI’s) pose significant challenges when applying existing design tools to inflatable structures. This gap is further exacerbated for dynamic applications as inflatable structures exhibit pressure-dependent natural frequencies and mode shapes. Surface-based structures must be designed with consideration given to operational sea state frequencies and wave periods so that the onset of structural instabilities (wrinkling, buckling) and loss of load-carrying capacities can be prevented.

The present research establishes the validity of physics based models using the Ideal Gas Law as an equation of state (EOS) to predict the natural frequencies and corresponding mode shapes of air-inflated drop-stitch fabric panels as functions of inflation pressure. Particular concern is given to the breathing modes for inflation pressures ranging from 5.0 to 30.0 psig. The presence of breathing modes can negatively impact the riding performance of RIBs vessels constructed with drop-stitch fabric hulls by amplification of the panel’s skin separation displacements and vertical accelerations, and are not seen in this material system for the pressures considered. Both numerical and experimental methods are pursued; the results of laboratory modal experiments are used to validate the numerical models. Predicted and experimental natural frequencies and mode shapes are compared and excellent correlation was observed. Increasing inflation pressures produced increasing in-plane and through-thickness normal stresses and modal frequencies of the drop-stitch fabric panels.
High-Order Immersed-Boundary Simulation and Error Analysis for Flow Around a Porous Structure
Authors: Zhang Meihua , Zheng Z. Charlie
Published: January 2018

In this study, a two-dimensional cylinder or a three-dimensional sphere is used as an example for a porous structure in the flow field. Immersed-boundary (IB) methods have been used to simulate flow around a cylinder/sphere, which is a typical problem to verify the effectiveness and accuracy of the methods. The flow was previously simulated by modeling the solid obstacles as a porous medium with flow resistivity. The current study makes an extension of the previous IB method. The fifth order WENO-Z scheme and third order Runge-Kutta method are used for space and time discretization, respectively. The Navier–Stokes equation is used for the fluids region and a ZK type of source term is applied in place of the forcing term for the porous domain. These two equations are solved simultaneously. Thus, there is no need to specify the interface conditions directly. In addition, the errors are estimated in terms of the flow resistivity that is zero for fluid, finite for porous, and infinite for non-porous solid. The aim of this paper is to establish estimates of the error induced by such an IB method. Numerical tests are performed to confirm the improvement of this method.
Evaluation of Damage Evolution in Nickel-Base Heat-Resistant Alloy Under Creep-Fatigue Loading Conditions
Authors: Suzuki Ken , Murakoshi Takuya , Sasaki Hiroki , Miura Hideo
Published: January 2018

In this study, interrupted creep and creep-fatigue tests of Alloy 617, which is a candidate alloy for boiler tubes and pipes of A-USC (advanced ultra-supercritical) power plants of the 700°C-class, were conducted to investigate damage evolution process. Also, the change of the micro texture of the alloy was continuously observed at a fixed area to elucidate the mechanism of damage evolution under creep and creep-fatigue loading from the viewpoint of the change of the order of atom arrangement using EBSD (Electron Back-Scatter Diffraction) analysis. The conditions of the creep test were a temperature of 800°C and the stress of 150 MPa in inert gas (99.9999% Ar). The stress-controlled creep-fatigue tests were carried out at 800°C in Ar using stress ratio R = −1 and hold time of 10 minutes at peak tension. IQ (Image Quality) values, which are the average sharpness of the obtained diffraction pattern, were used for evaluating the change of the micro texture during the tests. In both creep and creep-fatigue test, intergranular cracks appeared. The IQ value decreased monotonically in the vicinity of grain boundaries with the decrease of fracture life, indicating that the crystallinity of grain boundaries degraded faster than that of grains. This localized damage around grain boundaries was attributed to the intergranular crack propagation in the creep and creep-fatigue test. In addition, all the grain boundaries with IQ value lower than 85% of IQ value in as-received specimen were found to be cracked during both creep and creep-fatigue test. Therefore, there was the critical IQ value around grain boundaries at which intergranular cracks occurred under creep or creep-fatigue loading condition.
Thermal Conductivity Enhancement of Phase Change Materials Through Aligned Metallic Nanostructures
Authors: Su Che-Fu , Su Junwei , Esmaeilzadeh Hamed , Wang Jirui , Fratto Edward , Charmchi Majid , Gu Zhiyong , Sun Hongwei
Published: January 2018

The high conductive nickel (Ni) nanoparticles mixed with paraffin wax at two different volume ratios were prepared to investigate thermal conductivity enhancement of Phase Change Material (PCM) under random and aligned particle distribution. For each particle concentration, two samples were prepared. After mixing of the particles into the melted paraffin through sonication, one sample was placed in a static magnetic field to align the nanoparticles while the PCM was allowed to solidify; whereas, the second sample was solidified immediately after sonication to obtain a randomly distributed nanoparticles in the solid PCM. The thermal conductivity of both nanoPCM samples along with a pure paraffin sample were measured experimentally. The conductivity of both nanoPCM samples were substantially higher than the pure wax and the sample with magnetically aligned nanoparticle exhibited significantly higher thermal conductivity in comparison to the randomly distributed nanoPCM sample. It was anticipated that the configuration of the metallic fillers that are parallelly aligned with the applied heat flux direction does enhance the heat dissipation through the particle chains. However, the magnitude of thermal enhancement and sample fabrication in larger scales require further research efforts.
Face/Core Debonding Characterization of Foam and Honeycomb Core Sandwich Structures Using Single Cantilever Beam Testing Method
Authors: Tauhiduzzaman Mohammad , Sabet Seyed Morteza , Carlsson Leif A.
Published: January 2018

Single Cantilever Beam (SCB) testing was conducted on foam and honeycomb core sandwich specimens to predict the fracture toughness and bonding strength. Adhesion characteristics can also be identified between facesheet and core materials conducting SCB test on precracked specimen. Disbonding under combined tensile and shear loading may involve failure modes such as kinking and cell buckling. Modified Beam Theory (MBT) method specifies required parameters to generate a least square plot based on experimentally determined compliance and disbond length obtained during the SCB test. Interfacial fracture toughness Gc, enumerated by following recommended data reduction methodologies, required to predict minimum Gc to initiate disbond growth. Finally, experimental compliance was compared with elastic foundation stiffness compliance to verify the performance of the test. Good agreement between two compliance solutions validates the accuracy of the SCB test.
Microfluidic Systems for Studying Chemical Reactions, Mixing, and Heat Transfer
Authors: Chiou Richard Y. , Mauk Michael G. , Varapula Dharma T. , Wang Senyu , Ruiz Carlos , Tseng Tzu-Liang (Bill)
Published: January 2018

Microsystems comprising microfluidic networks and miniaturized actuators, transducers, and sensors provide a convenient, revealing, and low-cost means for studying chemical reactions, separation processes such as filtration and extraction, phase changes, mixing, heat and mass transfer, and fluid flow phenomena. For instance, palm-sized plastic cartridges or cassettes (‘chips’) with channels, chambers, manifolds and other components for flow control and fluid actuation can be instrumented with embedded thermocouples and pressure sensors, and operated with small Peltier coolers/heaters and programmable syringe pumps or microrotary pumps. With proper design, the on-chip microfluidic processes can also be imaged with CCD cameras (especially using fluorescent dyes and particles), and infrared thermal cameras for temperature profiling. Such image (including video) capture and processing affords much more data compared to point sensors such as thermocouples and pressure transducers, and can be directly compared with finite element modeling. These systems are effective vehicles for project-based learning in fluid mechanics, heat transfer, chemical reaction engineering, separation processes and other unit operations, process control, and various biotechnical operations such as enzymatic digestion, nucleic acid amplification, and sample fractionation. The chips are made as bonded laminates from patterned acrylic, polycarbonate, thin metal sheet, and many other material types.

Students can quickly design (using CAD software such as SolidWorks™), simulate (using FEM programs such as Comsol) microfluidic platforms, that can be rapid prototyped with laser machining, 3D printing, CNC machining, soft lithography, engraving and printed circuit board fabrication methods with a turn-around time of 1 day. The chip is instrumented using LabView™ or an Arduino™ microcontroller for data acquisition and process control. These benchtop or desktop systems make only modest demands on the resources of educational institutions, due to their low cost and safety, and minimal waste generation and reagent consumption. Also, their multidisciplinary nature affords an excellent opportunity for students to integrate their knowledge of CAD, simulation, prototyping, instrumentation and microcontrollers, statistical data analysis, and image processing and analysis. Further, these experiments give students a high level of hands on interaction and visualization of important unit operation processes. We discuss in detail some representative systems for heat exchangers, mixers, chemical reactors, and crystal growth, and their use as educational, project-based modules in the undergraduate engineering curriculum.
Design of Portable Patient Lift System for Assistant Living Homes
Authors: Dong Janet , Cheek Karina , Duncan John , Kalnasy Alex
Published: January 2018

The portable patient lift system is a Senior Capstone Design project that is defined through the collaboration between the University of Cincinnati and a retirement/assisted living community in Cincinnati. The objective of the project is to design, build, and test a lift system that is capable of safely lifting fallen elderly patients at assistant living homes out of tight spaces. Two student teams in 2015–2016 and 2016–2017 academic years had taken on this project. They applied the product development process which they learned from their senior year to develop a workable system. Their work started with survey, interviews, research, followed by developing alternative concept designs. The pros and cons of each concept were discussed, analyzed, and evaluated among peers, advisors, and Maple Knoll nurses. The final design of using inflatable method to lift patients was justified as the best option. Two final concept designs from each year were then manufactured or assembled in school. The testing of the final systems were conducted and demonstrated at Maple Knoll senior community. The expectations from nursing staff and senior residents were greatly satisfied.

This paper will describe our senior capstone design and product development process of such portable patient lift system, and discuss our experiential learning experience at Maple Knoll and lessons learned from design and making such system with focus on the consideration of seniors and their capabilities at settings of nursing homes.
Miniaturized Focused Ultrasound Transducers for Intravascular Therapies
Authors: Kim Jinwook , Wu Huaiyu , Jiang Xiaoning
Published: January 2018

Intravascular ultrasound approach has shown its advantages for thrombectomy. Catheter-directed ultrasound techniques have realized safe therapies by suppressing mechanical contact and penetration of excessive ultrasound energy through the tissue. One limitation of this approach is the lack of the sufficient ultrasound energy for fast thrombectomy because typical catheter-mounted transducers have high-frequency and low acoustic power. In this work, we aim to resolve this problem by designing miniaturized focused ultrasound transducers for improved therapeutic efficacy, which can generate low-frequency, sufficient pressure output within the confined insonation beam. This study builds upon our previous initial design of sub-megahertz, forward-looking, focused ultrasound transducers for preliminary in vitro study on microbubble-mediated thrombolysis. 650 kHz, forward-looking, concave-aperture ultrasound transducers were designed and mounted on 5–6 F catheters. The effect of design factors including aperture diameter, radius-of-curvature, and concave lens acoustic impedance on focusing performance were analyzed by using finite element analysis. Although the theoretical prerequisites for ideal beam focusing were not fulfilled due to the spatial limitation, the simulation results showed that practical design of the concave lens with the small geometrical aperture still enables to generate confined beam with a reasonable focal gain. Experimental validation results confirmed that the focal gain of 9 dB can be achievable. The measured transmitting sensitivity of the concave aperture transducer is 22.5 kPa/Vpp.
Investigations on Dimensional Accuracy of Stamped Tailor Welded Blanks Under Warm Forming Conditions
Authors: Satya Suresh Vakada Venkata Naga , Regalla Srinivasa Prakash
Published: January 2018

This work emphasizes on the geometric and dimensional accuracy of cylindrical tailor welded blank (TWB) components manufactured under warm forming conditions. In this work, TWB sheet material made of austenitic stainless steel (ASS 304 Grade) and deep drawing steel (IS 513 grade) materials were TIG welded before subjecting to stamping operation. Numerical simulations were validated with experimental results. Simulation results were analyzed to check the thickness variation and stress distribution within the component which otherwise would be difficult to measure experimentally. Measurements in terms of geometric accuracy gave encouraging results. The roundness and perpendicularity measurements indicated better accuracy whereas, cylindricity value has slightly improved. However, dimensional accuracy of the parts in terms of thinning, cup height and diameter has deteriorated. It was found that the spring back effect played a significant role in the deterioration of dimensional accuracy. Presence of residual stresses might be the cause for this effect; further studies are needed to address this issue.
Design of a New Testing Fixture for Tangential Stress Measurements in Pipes
Authors: Seibi Abdennour , Chaari Majdi , Temani Ahmed , Mokhtari Mehdi , Taylor Charles
Published: January 2018

Experimental estimation of acurate material properties are key elements to the design of machine components and structures. In general, the elastic properties were determined using uniaxial tensile tests regardless of the final shape of the product including pipes, which exhibit different elastic properties in the longitudinal and tangential directions due to their manufacturing process. Several attempts have been made to estimate the mechanical properties of pipes along their longitudinal directions including ASTM D2290 and exhibited inconsistent results; thereby, calling for further design and analysis. This paper, therefore, presents various design alternatives to the ring hoop tensile test adopted in the ASTM D2290 standard through finite element modeling. The design optimization consisted of varying the ring width, dogbone width, dogbone gauge length, and the spacing between the two D-blocks to obtain the optimum values of the varying parameters that provide uniform normal stress across the cross-sectional area of the dogbone and more representative mechanical response. Finite element results revealed that the proposed dogbone sample design has an optimum length to width ratio of 4 with an orientation angle between 75° to 105° with respect to the horizontal axis. The proposed model was compared to adopted test methods such as ASTM D2290 and resulted in comparable stress contours uniformity across the dogbone gauge length but different contact pressure values. it was also found that the contact pressure for the ASTM ring hoop tensile test is higher than that for the proposed model by 22%.
Solar Thermal-Driven Multiple-Effect Thermosyphon Distillation System for Waste Water Treatment
Authors: Shabgard Hamidreza , Xu Ben , Parthasarathy Ramkumar
Published: January 2018

A solar thermal-driven multiple-effect thermosyphon distillation (METD) system is proposed for waste-water treatment. The METD system consists of a series of cascaded thermosyphons that are connected by embedding the condenser section of each thermosyphon in the evaporator section of the following device. The input thermal energy is supplied by a solar collector integrated with a latent heat thermal energy storage unit. A thermal network model is developed to predict the heat transfer rates through the METD system and distilled water production rates. METD systems with various number of effects and hot end temperatures are investigated. It is found that the ratio of distilled water production to the input thermal energy increases by increasing the number of effects with no dependence on the hot end temperature. Quantitatively, a METD system with 5 effects can produce 11 kg of fresh water per hour with an input heat of 1.4 kW.
Micropolar Fluid Flow Between Two Inclined Parallel Plates
Authors: Hazbavi Abbas , Sharhani Sajad
Published: January 2018

In this study, the hydrodynamic characteristics are investigated for magneto-micropolar fluid flow through an inclined channel of parallel plates with constant pressure gradient. The lower plate is maintained at constant temperature and upper plate at a constant heat flux. The governing equations which are continuity, momentum and energy are are solved numerically by Explicit Runge-Kutta. The effect of characteristic parameters is discussed on velocity and microrotation in different diagrams. The nonlinear parameter affected the velocity microrotation diagrams. An increase in the value of Hartmann number slows down the movement of the fluid in the channel. The application of the magnetic field induces resistive force acting in the opposite direction of the flow, thus causing its deceleration. Also the effect of pressure gradient is investigated on velocity and microrotation in different diagrams.
Optimization of Corrosion Behavior in Submerged Friction Stir Processed Magnesium AZ31B Alloy
Authors: Ramaiyan Sankar , Mani Udayakumar , Chandran Rathinasuriyan , Velukkudi Santhanam Senthil Kumar
Published: January 2018

In this research, friction stir processing of AZ31B magnesium alloy of 6 mm thickness was done in submerged conditions. The process parameters, i.e. tool pin profile (simple cylindrical, stepped cylindrical, stepped square), rotational speed ranging from 800 to 1200 rpm and traverse speed ranging from 0.5 to 1.5 mm/sec were optimized using the multi response optimization technique. The experiment was conducted with L27 orthogonal arrays. The Immersion test and hardness have been considered as output response. From the view of an application, it would be more significant to optimize the Immersion Corrosion rate and Hardness of Submerged Friction Stir Processed AZ31B alloy. Thus, this study aims at optimizing the process parameters, including various tool pin profiles, feed rates and rotational speeds with corrosion rate and micro hardness using TOPSIS. Using analysis of variance (ANOVA), the most significant parameter effect of the submerged friction stir processing was determined.
Experimental Investigation on Solid State Resistance Spot Welding
Authors: Wu Zhijun , Zhang Guanlin , Wang Bingxu , Shih Kelvin
Published: January 2018

Resistance Spot Welding (RSW) is one of the most common and dominant technologies utilized in the automotive industry to join the thin sheet metals together, and expulsion is a common phenomenon during the operation. How to ensure the high quality nugget formation and joining performance is essential to ensure the quality and integrity of structures. In this study, solid state resistance spot welding is introduced in order to prevent expulsion. The effect of welding current and welding time on the mechanical performance of the solid state RSW in terms of nugget size, tensile performance and nugget formation will be investigated experimentally by using steel sheet metals. Microstructure and micro-hardness of the nugget cross-section will be evaluated as well.
On the Use of Gas Flow Models to Predict Leak Rates Through Sheet Gasket Materials
Authors: Bouzid Abdel-Hakim , Aweimer Ali Salah Omar
Published: January 2018

The prediction of leak rate through porous gaskets for different gases based on test conducted on a reference gas can prevent bolted joint leakage failure and save the industry a lot of money. This work gives a basic comparison between different gas flow models that can be used to predict leak rates through porous gasket materials. The ability of a model to predict the leak rate at the micro and nano levels in tight gaskets relies on its capacity to incorporate different flow regimes that can be present under the different working conditions. Four models based on Navier-Stokes equations and incorporate the boundary conditions of the appropriate flow regime considered. The first and second order slip, diffusivity and molecular flow models are used to predict and correlate leak rates of gases namely helium, nitrogen, SF6, methane, argon and air passing through three frequently used nanoporous gasket materials which are flexible graphite, PTFE and compressed fiber.

The methodology is based on the determination experimentally of the porosity parameter (N and R) of the micro channels assumed to simulate the leak paths present in the gasket using helium as the reference gas. The predicted leak rates of different gases at the different stresses and pressure levels are confronted to the results obtained experimentally by measurements of leak rates using pressure rise and mass spectrometry techniques. The results show that the predictions depend on the type of flow regime that predominates. Nevertheless the second order slip model is the one that gives better agreements with the measured leaks in all cases.