bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Modeling of Knee Mechanics
Authors: Nicolella Daniel P. , Bichon Barron , Francis W. Loren , Eliason Travis D.
Published: August 2012

It is widely accepted that the mechanical environment within the knee, or more specifically, increased or altered stresses or strains generated within the cartilage, is a leading cause of knee osteoarthritis (OA). However, a significant unfulfilled technological challenge in musculoskeletal biomechanics and OA research has been determining the dynamic mechanical environment of the cartilage (and other components) resulting from routine and non-routine physical movements. There are two methods of investigating musculoskeletal joint mechanics that have been used to date: 1) forward and inverse multibody dynamic simulations of human movement and 2) detailed quasi-static finite element modeling of individual joints. The overwhelming majority of work has been focused on musculoskeletal multibody dynamics modeling. This method, in combination with experimental motion capture and analysis, has been integral to understanding torques, muscle and ligament forces, and reaction forces occurring at the joint during activities such as walking, running, squatting, and jumping as well as providing key insights into musculoskeletal motor control schemes. However, multibody dynamics simulations do not allow for the detailed continuum level analysis of the mechanical environment of the cartilage and other knee joint structures (meniscus, ligaments, and underlying bone) within the knee during physical activities. This is a critical technology gap that is required to understand the relationship between functional or injurious loading of the knee and cartilage degradation. We have developed a detailed neuromuscularly activated dynamic finite element model of the human lower body and have used this model to simultaneously determine the dynamic muscle forces, joint kinematics, contact forces, and detailed (e.g., continuum) stresses and strains within the knee (cartilage, meniscus, ligaments, and bone) during several increasingly complex neuromuscularly controlled and actuated lower limb movements. Motion at each joint is controlled explicitly via deformable cartilage-to-cartilage surface contact at each articular surface (rather than idealized as simple revolute or ball and socket joints). The major muscles activating the lower limb are explicitly modeled with Hill-type active force generating springs using anatomical muscle insertion points and geometric wrapping. Muscle activation dynamics were determined via a constrained optimization scheme to minimize muscle activation energy. Time histories of the mechanical environment of all soft tissues within the knee are determined for a simulated leg extension.
An Analysis of Stand-Up Forklift Accidents From the 1970’s to 2006
Authors: Berry Thomas A.
Published: August 2012

This paper presents the analysis of 3234 accident reports relating to stand-up forklifts that have occurred from the time period of 1977 to 2006 that were reported to a certain company either by the employer or dealer. Included will be a consideration of the accident type and severity. Specific emphasis will be placed upon the incidents involving serious injuries to operators along with recommendations for reducing the risk of injury to the operator.
Automatic Generation of a Subject Specific Upper Body Model From Motion Data
Authors: Lura Derek , Carey Stephanie , Dubey Rajiv
Published: August 2012

This paper details an automated process to create a robotic model of a subject’s upper body using motion analysis data of a subject performing simple range of motion (RoM) tasks. The upper body model was created by calculating subject specific kinematics using functional joint center (FJC) methods, this makes the model highly accurate. The subjects’ kinematics were then used to find robotic parameters. This allowed the robotic model to be calculated directly from motion analysis data. The RoM tasks provide the joint motion necessary to ensure the accuracy of the FJC method. Model creation was tested using five healthy adult male subjects, with data collected using an eight camera Vicon© (Oxford, UK) motion analysis system. Common anthropometric measures were also taken manually for comparison to the FJC kinematic measures calculated from marker position data. The algorithms successfully generated models for each subject based on the recorded RoM task data. Analysis of the generated model parameters relative to the manual measures was performed to determine the correlations. Methods for replacing model parameters extracted from the motion analysis data with hand measurements are presented. The accuracy of the model generating algorithm was tested by reconstructing motion using the parameters and joint angles extracted from the RoM tasks data, correlated manual measurements, and height based correlations from literature data. Error was defined as the average difference between the recorded position and reconstructed positions and orientations of the hand. For all of the tested subjects the model generated using the RoM tasks data showed least average error over the tested trials. Each of the tested results were significantly different in position error with the FJC generated model being the most accurate, followed by the correlated measurement data, and finally the height based calculations. No difference was found between the end effector orientation of generated models. The models developed in this study will be used with additional subject tasks in order to better predict human motion.
A New Precision Non-Contact Laser-Based Hybrid Measurement Methodology
Authors: Shetty Devdas , Ghosh Suhash , Campana Claudio , Atalay Mustafa
Published: August 2012

Precise and accurate manufacturing became an obligation in aerospace industry in last decades. Uniformity of turbine blades, nozzle geometries, gaps, diameter changes and misalignment issues in turbine assemblies have to be inspected carefully in terms of quality and exactitude. Like broadly used aluminum and titanium based materials, ceramics and special coated composites are also used in aerospace applications. A wide selection of measurement methods used is based on intensity sensing and range imaging. With the recent development in advanced laser techniques, new methods that involve non contact measurement methodologies are being investigated by many industries. In addition to their accuracy and precision, speed of measurement and compactness of such systems are also of high significance. In this paper, a hybrid approach consisting of laser based triangulation, photogrammetry and edge detection techniques has been investigated to measure inner surfaces of parts that have limited access, especially where human presence is impossible. The system is capable of detecting and measuring misalignments, gaps, inclinations as well as surface variations such as cracks and dents. The system employs the accuracy and speed of measurement of triangulation systems and combines these with the mobility and cost effectiveness of photogrammetry and edge detection techniques. In addition to gap and alignment offset inspections, the methodology and the instrument enables angle measurements, detailed surface texture examinations and other inspections needed to be done inside assemblies with narrow openings, with its compact body. Additionally, a comprehensive experimental study has been conducted to show that two different edge detection methods, namely, the “Simple Edge Tool” and “Straight Edge (Rake) Tool” can be used with great accuracy and precision for such measurement purposes. With this system, any surface, whether they have a reflectance or not, can be scrutinized.
Comparative Economic Analysis of Concentrating Solar Technologies
Authors: Duquette Brandon , Otanicar Todd
Published: August 2012

One of the noted benefits of concentrating photovoltaics (PV) is the reduced cell area which results in reduction of the overall system cost. A variety of studies have looked at the cost for concentrating PV systems and made comparisons to concentrating solar thermal power plants, typically resulting in concentrating solar thermal power having lower system costs. Recently a widespread design space was assessed for the potential efficiency improvements possible with a coupled hybrid PV/thermal solar energy system for electricity generation. The analysis showed that modest efficiency improvements could be made but no assessment of the economic impact was made. Although modest efficiency gains can be made such a hybrid system requires more components than one of the conventional stand alone concentrating solar power plant on its own resulting in significantly different system costs. As a result we look to compare the overall system costs of three different solar power technologies: concentrating PV, concentrating solar thermal, and the concentrating hybrid approach. Additionally we will focus on documenting the necessary hybrid efficiencies to make a hybrid system competitive as well as the feasibility and means for achieving these efficiencies.
Model Based Actuator Management for a Hydraulic Active Suspension System: Improving Comfort Performance by Advanced Control
Authors: De Bruyne Stijn , Anthonis Jan , Gubitosa Marco , Van der Auweraer Herman , Desmet Wim , Swevers Jan
Published: August 2012

Active suspension systems aim at increasing safety by improving vehicle ride and handling performance while ensuring superior passenger comfort. This paper addresses the influence of the actuator management on the comfort performance of a complete hydraulic active suspension system. An innovative approach, based on nonlinear Model Predictive Control, is proposed and compared to a classical approach that employs a steady-state performance map of the actuator. A simulation analysis shows how taking into account actuator dynamics improves the actuator’s force tracking performance, leading to an improvement of the overall vehicle comfort performance.
A Design of Experiments Approach to Identifying Damage in Structures Using Modal Frequency
Authors: Downer Lee M. , Rideout D. Geoff
Published: August 2012

Modal vibration parameters such as frequency, damping ratio and mode shape have long been considered useful for identifying damage in structures. In this paper a generalized approach is presented that allows for damage to be localized and quantified using regression and response surface modeling of modal frequency. Regression models or response surface models are developed to characterize how modal frequencies of structures are affected by variations in parameters such as defect depth, width and location. Design of experiments (DOE) techniques are used in conjunction with experimental modal frequency measurements to solve for defect parameters of test specimens in the field for condition monitoring. Determining defect parameters can be done by inverting and explicitly solving regression model equations, employing software-driven numeric optimization or through a graphical approach that overlays contour lines of multiple response surface models. Either of these methods can be automated. This approach is explored and validated with finite element and theoretical beam models along with a series of physical experiments on cantilevered aluminum rods. The method performs well for detecting simple and distinct defects. Implementation complexity increases when detecting multiple or more variable, less-easily quantifiable defects. In its general form, the method shows promise for damage detection when a specific type of consistent defect is known to occur or for applications such as quality control on production lines and monitoring of deposit buildup in pipes.
Heat Transfer Performance for a Falling-Film on Horizontal Flat Tubes
Authors: Wang X. F. , Hrnjak P. S. , Elbel S. , Jacobi A. M. , He M. G.
Published: August 2012

Local and average heat transfer behavior for a falling film on horizontal flat tubes is explored through an experimental approach in this work. Experiments are conducted using water (18 °C) under different heat fluxes and tube spacings, with a range of flow rates that covers all flow modes. It is found that the local heat transfer coefficient decreases with distance from the top of the tube and is almost constant along the axial direction. Heat flux and tube spacing have almost no effect on average heat transfer performance within the experimental range. The average Nusselt number for the flat tube is close to that for round tube in a droplet flow mode, but it is almost twice as large as the round-tube result in the jet mode and sheet modes.
Identifying Product Scaling Principles: A Step Towards Enhancing Biomimetic Design
Authors: Perez Angel , Linsey Julie , Tsenn Joanna , Glier Michael
Published: August 2012

Designers are often faced with the problem of taking a solution at one scale and mapping it to another, often occurring with design-by-analogy and bioinspired design. Despite various scaling laws for specific systems, scaling a solution is a difficult process since different physical principles are often used (causing scaling laws to be invalid) and numerous other changes must be made. This is one of the likely reasons that bioinspired design is difficult. An empirical product study method was used to determine five scaling principles by studying numerous example products. As an initial validation, a design case study applied these principles to a single passenger, low-cost, golf transportation system. Few solutions exist for a single passenger golf transportation system due to difficulties in meeting the customer’s needs, including a portable design which fits in an average sized car trunk at an affordable price. Utilizing the golf bag push cart, full-size two passenger golf cart and scaling principles, a solution was established that fulfilled the design problem. By performing this case study, the general scaling principles are confirmed as a viable aid in product design scaling. This study provides an initial step in creating new innovative designs based on existing solutions in nature or other products that occur at very different scales. Much further work is needed by studying additional products and bioinspired examples. The design principles also need to be more robustly validated.
Use of Multiple Choice Questions as an Assessment Tool in Dynamics
Authors: Ghosh Amitabha
Published: August 2012

Dynamics is a pivotal class in a student’s life-long learning profile since it builds upon the logical extensions of Statics and Strength of Materials classes, and provides a framework on which Fluid Mechanics concepts may be developed for deformable media. This paper establishes the contextual reference of Dynamics in this framework. An earlier paper by the author discussed details of how the design of proper multiple choice questions is critical for assessment in Statics and Fluid Mechanics. This paper provides a progress report of such evaluations in Dynamics. In addition, this paper explores the pedagogical issues related to building a student’s learning profile. While comparing test results obtained in trailer sections of Dynamics with those obtained in sections taught by faculty teams, some structural differences were discovered. This reporting completes the feedback loop used by faculty in our Engineering Sciences Core Curriculum for improving student performance over time. The process may further be developed by using some similarities and differences in the performance data.
Dynamic Analysis of Three Parallel Beams With Electrostatic Force Interaction
Authors: Hassanpour Pezhman A. , Nieva Patricia M. , Khajepour Amir
Published: August 2012

In this paper, the dynamics of a micro-machined structure with three parallel cantilevers is investigated. The cantilevers are electrically charged and apply electrostatic force to each other. The governing equations of motion are derived using Euler-Bernoulli beam theory and considering structural modal damping. The stability condition of the beams for various electric charges is also studied. In addition, the equations of motion are integrated to obtain the response of the beams in time-domain for a range of initial conditions. This response is used to study the behavior of the beams at the stability margin. The end application of the structure under investigation is in the device characterization. The dynamic stability condition and time-domain responses are used to investigate the reliability of the characterization. Once translated back to physical quantities, these results can be used for improving the measurements.
Enhanced Specific Heat Capacity of Molten Salts Using Organic Nanoparticles
Authors: Jo Byeongnam , Banerjee Debjyoti
Published: August 2012

In this study we explore the material properties of carbonate salt eutectics that melt at high temperatures (exceeding 480 °C). These salt eutectics demonstrated anomalous enhancement in the specific heat capacity in both solid and liquid phases — when mixed with carious organic nanoparticles such as carbon nanotubes (CNT) and graphite nanoparticles. Theses experimental measurements are compared with previous reports in the literature for exploring the effect of the synthesis protocol on the resulting thermo-physical properties of these nanomaterials. The enhancement of the thermo-physical properties on mixing with nanoparticles is of significant interest in reducing the cost of thermal energy storage (TES) devices and systems. TES can be utilized for levelizing peaks in cyclical energy demands (or duties) that is typical of renewable energy applications where the input energy source may be intermittent (e.g., solar thermal); as well as in geothermal and nuclear energy applications.
Development of a Time-Resolved Catadioptric Stereo Digital Image Correlation Technique for the Study of Blast Loading of Composite Material Structures
Authors: Jahnke Douglas , Andreopoulos Yiannis
Published: August 2012

Impingement of blast or shock waves on structures is characterized by a substantial transient aerodynamic load that develops over the short time associated with the shock reflection time scale. This mutual interaction between the shock wave and the structure can cause significant deformation of the structure and high strain rates within the material resulting in damage. While accelerometers, strain gages and other single point measurement probes and their corresponding techniques can provide valuable information of the local displacement and strain during blast loading, better understanding of the complex phenomena involved in these interactions require time dependent information acquired simultaneously from multi points on the structure. Digital Image Correlation is a full-field noncontact optical technique which can provide time dependent information of the displacement of the structure and the resultant high strain rates generated during the loading. The present setup consists of a single high-frame-rate camera which can accommodate two simultaneous stereo images of the deforming structure on its CMOS chip. Four different planar mirrors, appropriately positioned, provide the stereo views of the specimen captured on the chip. The present layout offers several advantages over traditional systems with two different cameras. First, it provides identical system parameters for the two views which minimizes their differences and thus facilitating robust stereo matching. Second, it reduces calibration time since only one camera is used and third its cost is substantially lower than the cost of a system with two cameras. The technique is being developed and tested in a large scale shock tube facility during loading by shock/blast wave of various impulses. The specimens used are flat plates made of high-alloy steel, aluminum or composite materials. In the present paper the development of the technique will be described and preliminary results of qualification tests will be presented and discussed.
Lattice Boltzmann and Discrete Ordinates Methods for Phonon Transport Modeling: A Comparative Study
Authors: Donmezer Fatma Nazli , Singh Dhruv , James William , Christensen Adam , Graham Samuel , Murthy Jayathi Y.
Published: August 2012

The description of heat transport at small length scales is very important in understanding a wide range of micro and nanoscale systems. In systems where coherent phonon transport effects are negligible, the Boltzmann transport equation (BTE) is often employed to describe the distribution and propagation of thermal energy in the lattice. The phonon distribution function depends not only on the temporal and spatial coordinates, but also on polarization and wave vector, making fully-resolved simulations very expensive. Therefore, there is a need to develop accurate and efficient numerical techniques for the solution of the BTE. The discrete ordinates method (DOM) and more recently, the lattice Boltzmann method (LBM) have been used for this purpose. In this work, a comparison between the numerical solution of the phonon BTE by the LBM and DOM is made in order to delineate the strengths and weaknesses of these approaches. Test cases are chosen with Knudsen (Kn) numbers varying between 0.01–100 to cover the full range of diffusive to ballistic phonon transport. The results show that solutions obtained from both methods converge to analytical results for the 1 dimensional phonon transport in a slab. Solutions obtained by two methods converge to analytical solutions of 2 dimensional problems at low Kn. However, solution accuracy is strongly determined by angular resolution for moderate to high Kn. Since the number of propagation directions in LBM are limited, significant errors are engendered in multi-dimensional acoustically-thin problems. DOM also suffers errors at low angular resolutions for high Kn, but yields accurate solutions when sufficient angular resolution is employed.
Computational Modeling of the Combustion and Gasification Zones in a Downdraft Gasifier
Authors: Muilenburg Marta , Shi Yunye , Ratner Albert
Published: August 2012

Computational modeling was completed on a simplified downdraft gasifier being installed at the University of Iowa Oakdale Power Plant. The model was created in Gambit and simulated in ANSYS Fluent. The process modeled was non-premixed combustion on biomass fuel with a fixed-bed. The Fluent coal model was modified based on (off-site) proximate and ultimate analyses of the biomass. Varying packing densities, oxidizer inlet velocities and fuel types were simulated and the impact on the combustion zone was assessed. It was found that packing densities around 0.5 with oxidizer inlet velocities less than 5m/s were ideal for modeling wood gasification and produced a temperature distribution that was the most analogous to previous experimental measurements. The resulting reaction field was mainly a large rich fuel combustion (RFC) zone where gasification and pyrolysis could occur. The different fuels were found to have similar temperature and mean mixture fraction patterns, although the maximum temperatures attained were very different (1080K for seed corn versus 678K for wood), with the wood showing a greater area of RFC for gasification and pyrolysis. The temperature contour corresponded to the mixture fraction figure perfectly and well explained the stable asymmetric combustion in a downdraft gasifier.
Real Time Application of Bearing Wear Prediction Model Using Intelligent Drilling Advisory System
Authors: Tahmeen Mazeda , Hareland Geir , Wu Zebing
Published: August 2012

The real-time prediction of bearing wear for roller cone bits using the Intelligent Drilling Advisory system (IDAs) may result in better performance in oil and gas drilling operations and reduce total drilling cost. IDAs is a real time engineering software and being developed for the oil and gas industry to enhance the performance of complex drilling processes providing meaningful analysis of drilling operational data. The prediction of bearing wear for roller cone bits is one of the most important engineering modules included into IDAs to analyze the drilling data in real time environment. The ‘Bearing Wear Prediction’ module in IDAs uses a newly developed wear model considering drilling parameters such as, weight on bit (WOB), revolution per minute (RPM), diameter of bit and hours drilled as a function of IADC (International Association of Drilling Contractors) bit bearing wear. The drilling engineers can evaluate bearing wear status including cumulative wear of roller cone bit in real time while drilling, using this intelligent system and make a decision on when to pull out the bit in time to avoid bearing failure. The wear prediction module, as well as the intelligent system has been successfully tested and verified with field data from different wells drilled in Western Canada. The estimated cumulative wears from the analysis match close with the corresponding field values.
An Experimental Study of Carbon Nanotube Reinforcements
Authors: Patrin Lauren , Chow Frank , Philippart Gabriela , Delale Feridun , Liaw Benjamin , Li Jackie , Chung Jerry , Liu Jim , Iyer Ramki
Published: August 2012

Due to their high strength and stiffness carbon nanotubes (CNTs) have been considered as candidates for reinforcement of polymeric resins. It is also known that the addition of CNTs to polymeric matrix results in highly conductive nanocomposites, making the material multifunctional. Most of the CNT reinforced polymeric nanocomposite systems reported in the literature have been studied at room temperature. However, in many applications, materials may be subjected from low to elevated temperatures. Thus, the aim of this research is to study CNT reinforced polypropylene (PP) specimens at room, elevated and low temperatures. ASTM standard Type I specimens manufactured via injection molding and reinforced with 0.2%, 1%, 3%, and 6% CNTs were first subjected to tensile loads in a universal testing machine at room temperature. Neat PP resin specimens were also tested to provide baseline data. The tests were repeated at −54°C (−65°F), −20°C (−4°F), 49°C (120°F) and 71°C (160°F). The results were plotted as stress-strain curves and analyzed to delineate the effect of CNT reinforcement percentage and temperature on the mechanical properties. It was noted that as the percentage of CNT reinforcement increases, the resulting nanocomposite becomes stiffer (higher Young’s modulus), has higher strength and becomes more brittle. Temperature has a drastic effect on the behavior of the nanocomposite. As the temperature increases, at a given reinforcement percentage the material becomes more ductile with significantly lower Young’s modulus and strength compared to room temperature. At lower temperatures, the nanocomposite becomes more brittle with higher stiffness and strength, but significantly reduced failure strain. Also electrical measurements were conducted on the specimens to measure their resistance. For specimens reinforced with up to 3% of CNTs no electrical conductivity was detected. As expected at 6% CNT reinforcement (which is above the approximately 4% percolation limit reported in the literature), the specimens became electrically conductive. To predict the mechanical properties obtained experimentally, a micromechanics based model is presented and compared with the experimental results.
Numerical Analysis of the Cross-Flow Under the Land in a Serpentine Flow Field of a PEM Fuel Cell
Authors: Taira Hidetaka , Liu Hongtan
Published: August 2012

Serpentine flow-fields are widely used in proton exchange membrane (PEM) fuel cells due to their various advantages, including providing a proper compromise between pressure drop and water removal capability. One of the advantages of serpentine flow fields is the cross-flow under the land through the gas diffusion layer (GDL) due to the pressure difference between adjacent channels. In this study, a three-dimensional PEM fuel cell model is developed to study the cross-flow effect under the land for both across and along the land directions. Simulation results of the flow distribution along and across the channel, and the relationship between the cross-flow and the pressure difference are presented. A parametric study is conducted to investigate the effect of the GDL permeability on the cross-flow rate. The cross-flow rate increases as the permeability becomes larger because the cross-flow velocity. However, cross-flow rate reaches an asymptotic value when the permeability is greater than 10−9 (m2) since the pressure difference between adjacent channels becomes smaller. The effect of the cross-flow on the local oxygen mass fraction is also investigated. The results show that oxygen concentrations in some locations are significantly higher due to the cross-flow under the land and secondary flows in the channel. Finally, by comparing average current densities between under the channels and the land areas, it is shown that the performance of the cell gradually decreases across the channel/land direction.
Bioinspired Jumping Mobility Concepts for Rough Terrain Mobile Robots
Authors: Gilani Omar , Ben-Tzvi Pinhas
Published: August 2012

Mobile robots face great challenges in terms of mobility when traversing rough terrain, especially obstacle filled environments. Current terrestrial locomotion mechanisms such as wheels, tracks, and legs, face difficulties surmounting obstacles equal to or greater than their own height. This is especially true for smaller robots. In this respect, bioinspired approaches offer some solutions. Some insects in particular tackle rough terrain locomotion by performing high powered jumps. Their morphology has evolved to create specialized energy storage structures, and their hind legs have adapted to provide improved mechanical leverage. This paper investigates jumping as employed by insects and develops principles pertinent for the design of a jumping robotic system. A mathematical model depicting bipedal jumping is presented. The model includes mechanical energy storage elements in the form of springs for the purpose of assessing jumping locomotion for robotic applications. This model will assist in analyzing jumping locomotion and presenting some insights, as well as rough dimensioning of system parameters to achieve desired jumping performance.
Motion Simulator for Collaborative Work Planning Between a Magnetically Levitated Robot and an Industrial Robot
Authors: Tarao Susumu , Tsuda Naoaki , Mehrtash Moein , Khamesee Mir Behrad
Published: August 2012

Magnetically levitated robots can move without lubrication, they generally have advantages to the use in the various special environments such as in a dust-free room, in a vacuum, in a flammable atmosphere, and in vivo. Meanwhile, they have a disadvantage of small working volume corresponding to the allowable air gap between the levitated object and the electromagnets. In some cases, to construct a combination of a magnetically levitated robot and an industrial robot which has a comparatively large working volume seems an effective way to expand the whole working volume. On that premise, we are developing an experimental system and simulator for collaborative work between a magnetically levitated robot and an industrial robot. This paper presents the system concept and the configuration of the simulator which is corresponding to the actual elements: magnetically levitated robot, industrial robot and manipulation device.
Investigation of Convective Heat Transfer of Aqueous Nanofluids in Microchannels Integrated With Temperature Nanosensors
Authors: Yu Jiwon , Kang Seok-won , Jeon Saeil , Banerjee Debjyoti
Published: August 2012

Forced convective heat transfer experiments were performed for internal flow of de-ionized water (DIW) and aqueous nanofluids (ANF) in microchannels that were integrated with a calorimeter apparatus and an array of temperature nanosensors. The heat flux and wall temperature distribution was measured for the different test fluids as a function of fluid inlet temperature, wall temperature, heat flux, nanoparticles concentration, nanoparticle materials (composition, nanoparticle size and shape) and flow rates. Anomalous behavior of the nanofluids in convective heat transfer was observed where the heat flux varied as a function of flow rate and bulk temperature. The heat exchanging surfaces were characterized using electron microscopy (SEM, TEM) to monitor the change in surface characteristics both before and after the experiments. Precipitation of nanoparticles on the walls of the microchannels can lead to the formation of “nano-fins” at low concentrations of the nanoparticles while more rampant precipitation at high concentration of the nanoparticles in the nanofluids can lead to scaling (fouling) of the microchannel surfaces leading to degradation of convective heat transfer — compared to that of pure water under the same experimental conditions. Also, competing effects resulting from the decrease in the specific heat capacity as well as anomalous enhancement in the thermal conductivity of aqueous nanofluids can lead to counter-intuitive behavior of these test liquids during forced convective heat transfer.
Anomalous Rheological Behavior of Complex Fluids (Nanofluids)
Authors: Jo Byeongnam , Jung Seunghwan , Shin Donghyun , Banerjee Debjyoti
Published: August 2012

The rheological behavior of various complex fluids was explored in this experimental study. Nanofluids were obtained by mixing nanoparticles with various solvents. The solvents consisted of metal salt eutectics that melt at high temperatures (exceeding 200 °C) depending on the composition of the metal salts in the eutectics. The rheological behaviors of these high temperature solvents were measured as a function of temperature before and after mixing with different types of nanoparticles (chemical composition, size, shape and concentration). These nanofluids exhibited non-Newtonian behavior (shear thinning behavior) while some of the other nanofluids were surprisingly found to have Newtonian behavior. It was observed that high aspect ratio nanoparticles (e.g., stick shaped carbon nanotubes) were more likely to cause shear thinning behavior of the resulting nanofluids.
Integrated Heterogeneous Micro-Nano Systems via Modular Designing and Flexible Assembly
Authors: Das Aditya , Murthy Rakesh
Published: August 2012

One of the major challenges in commercializable micro-nano systems development is the high cost and turnaround that are incurred through multiple product-optimization iterations and expensive fabrication processes for specific systems. Development of complex and heterogeneous micro-nano systems, that are only possible through assembly and not by conventional surface machining approaches, are further impeded by lack of standard design rules and off-the-shelf robotic manipulation systems. Dedicated hardware and system specific component designs, although possible, are not commercially viable for addressing the wide range of opportunities that exists in the prevailing micro-nano domain. In this paper, we present an alternative and holistic top-down approach for micro-nano manufacturing using modular part designs and flexible assembly systems. We incorporate, seamlessly, multiple novel algorithms related to microrobotics and scaling of physics, obtained both analytically as well as experimentally; in order to predict, track and control the uncertainty propagation in a typical manufacturing process, in micro-nano scale, throughout production steps including design, machining, setup, assembly, testing etc. We demonstrate, through multiple examples, the implementation of the proposed framework in micro-nano scale manufacturing.
Rheological Properties of “Dry Water”
Authors: Taylan Onur , Berberoglu Halil
Published: August 2012

This study reports the rheological properties of the novel material “dry water” which contains about 98% by weight water but resembles a dry powder. Dry water is a water-in-air inverse foam which consists of microscopic water droplets encapsulated with hydrophobic fumed-silica nanoparticles. This novel material offers a large surface to volume ratio on the order of 2 × 105 m2/m3 for the gas and water phases. Thus, it provides a convenient medium for surface area limited processes and finds applications from cosmetics to gaseous fuel storage. In this study both steady and dynamic rheological properties of dry water were measured. In particular, the elastic (G′) and viscous (G″) moduli, and the complex dynamic shear viscosity (η*) were recovered from experimental data. Results showed that both the elastic and viscous moduli decreased with increasing strain at strains larger than 4%, and both moduli are weak functions of rotational frequency. Complex dynamic shear viscosity decreased with strain and rotational frequency. When compared with the studies in literature, rheological experiments and obtained results indicated that dry water behaves as a gel rheologically under the investigated conditions.
Blast Loading on Sandwich Structures: A Critical Assessment
Authors: Abrate Serge
Published: August 2012

Sandwich structures are used in many applications in which they are subjected to blast loading due in-air or underwater explosions. In an early phase, the response is dominated by the propagation of waves through the thickness of the sandwich structure which can result in severe damage to the core and debonding. At a later stage, the response if dominated by the overall bending of the structure. A thorough analysis shows that existing plates and shell theories cannot predict the early phase response and that a separate analysis in needed. The behavior of sandwich structures under blast loading depends on the type of core used and the properties of these cores. Constitutive equations and failure criteria will be discussed. We compare the mechanical properties of several types of core: foam, honeycomb, lattice, and corrugated cores. Models with various levels of complexity are developed and to determine the different types of behavior observed during blast loading of sandwich structures. The study of submerged structures subjected to underwater blasts is of particular interest in this study and both evacuated and fluid-filled structures are considered. The complex interaction of the shock wave with a cylindrical or spherical shell is analyzed using a ray tracing approach that accurately predicts the many wavefronts observed during experiments.
Numerical Simulation of a PAK-B Airfoil Using Fully Turbulent and Transition-Sensitive RANS Models
Authors: Dhakal Tej P. , Jamal Tausif , Walters D. Keith
Published: August 2012

Numerical simulations of a PAK-B airfoil cascade have been performed using commercially available fully turbulent and transition-sensitive RANS models. A range of Reynolds numbers (25000 to 300000) and free-stream turbulence intensities (0.5% and 9%) were considered. Test conditions matched experiments by Volino (2002), and results from both turbulent and transition-sensitive RANS models are compared with the available experimental data. Two-equation fully turbulent RANS models failed to accurately predict the separation and reattachment region on the suction side of the airfoil. At Reynolds number 100000 and higher, in contrast to the experimental results, the SST model failed to predict flow separation even for low free-stream turbulence intensity cases. The transition sensitized RANS models; for instance transition-sensitive SST, and k-kL-ω models were able to predict separation and reattachment in most of the test cases. The k-kL-ω model produced reasonable results for low free-stream turbulence intensity cases, while the transition sensitized SST model results were close to experimental results for high free-stream turbulence intensity cases. Predicted location of the separation point was almost independent of Reynolds number for both transition models.
Flexible Graphene Sensors for Explosive Trace Detection
Authors: Lee Je Kyun , Green Steven , Song Sangyup , Phamduy Paul , Kim Byungki
Published: August 2012

This paper presents an explosives sensor. The sensor consists of graphene spray coated onto a substrate with electrodes patterned on the surface. The substrates included glass and flexible polyethylene terephthalate (PET), and the leads were gold and silver respectively. Testing utilizing dinitrotoulene 2,4 (DNT) in a closed container showed the validity of using glass/gold based substrate with a graphene oxide coating as explosive sensors.
Kinematic and Workspace Analysis of a 2-DOF Haptic End-Effector That Carries Out a Developable Haptic Strip
Authors: Covarrubias Mario , Bordegoni Monica , Cugini Umberto , Mansutti Alessandro
Published: August 2012

This paper presents the analysis of a 2 DOF end-effector that carries out a haptic tool consisting in a developable servo-actuated plastic strip. To overcome some drawbacks of conventional systems related to the use of point based force-feedback, tactile and glove devices we have developed the triangular mesh approach in the developable haptic interface. The developable haptic strip, has evolved as a result of this research. The haptic interface of our system consists of a haptic strip that is inspired by the deformable tape that designers use for creating and modifying aesthetic shapes. The first step for designing the end effector and the haptic strip mechanism has been the assignment of both the total length of the haptic strip and the number of tessellation triangles required to control the strip as a developable surface. The strip is aimed at haptically rendering medium sized design objects (vases, lamps, household appliances, etc.). Thus, the total length of the strip has been set to be 160 mm. This length value also ensures the possibility to easily manipulate the strip. Seven triangles have been assigned in order to maintain the haptic strip symmetric; this consideration is particularly important because guarantees an adequate balancing of weight in the mechanism. The device is based on a modular architecture of elements that deform a plastic tape.
Diesel Oxidation Catalyst Control of Hydrocarbon Aerosols From Reactivity Controlled Compression Ignition Combustion
Authors: Prikhodko Vitaly Y. , Curran Scott J. , Barone Teresa L. , Lewis Samuel A. , Storey John M. , Cho Kukwon , Wagner Robert M. , Parks James E.
Published: August 2012

Reactivity Controlled Compression Ignition (RCCI) is a novel combustion process that utilizes two fuels with different reactivity to stage and control combustion and enable homogeneous combustion. The technique has been proven experimentally in previous work with diesel and gasoline fuels; low NOx emissions and high efficiencies were observed from RCCI in comparison to conventional combustion. In previous studies on a multi-cylinder engine, particulate matter (PM) emission measurements from RCCI suggested that hydrocarbons were a major component of the PM mass. Further studies were conducted on this multi-cylinder engine platform to characterize the PM emissions in more detail and understand the effect of a diesel oxidation catalyst (DOC) on the hydrocarbon-dominated PM emissions. Results from the study show that the DOC can effectively reduce the hydrocarbon emissions as well as the overall PM from RCCI combustion. The bimodal size distribution of PM from RCCI is altered by the DOC which reduces the smaller mode 10 nm size particles.
Design and Utility of Specialist Comminution Set-Up for Plastics and Organic Materials
Authors: Macko Marek , Mrozin´ski Adam , Flizikowski Jo´zef
Published: August 2012

A proposal of design of comminution set-up for plastics and organic materials has been presented. Some methods using modelling for optimisation and development of the comminution devices construction for plastics-, bio- and fibre as non-brittle materials (waste) has been mentioned too. The set-up take into consideration two beings: mathematically and design modelling. The common set is composed of characteristics, structure, relationships, effectiveness and progress of the machinery engineering, e.g. breaking up in the plastics-, bio- and fibres waste recycling process. We have been paid special attention to refining stage in stock preparation which plays an important role in developing the properties of stock for paper production. We would like to present some innovation of grinding systems: granulation, comminution and grinding where research, development and knowledge-based robots applications — in this field — have crucial importance from the point of view of process improvement and final product quality.
Electrophoretic Mobility of Lipid Coated Nanoparticles: Understanding the Influence of Size and Charge on a Lipoprotein Particle Mimic
Authors: Reed Scott M. , Wang Min S. , Curello Erica L.
Published: August 2012

Elevated levels of low-density lipoprotein (LDL) are associated with increased risk of coronary heart disease (CHD). Although smaller LDL particles are more atherogenic, it is not clear how LDL particle size influences atherogenesis. Smaller particles may be more prone to macrophage uptake and plaque formation. Alternatively, increased rates of lipid oxidation may explain the atherogenic effects of smaller LDL. We have developed a mimic of LDL that allows independent examination of the effect of LDL size and oxidation. We have engineered LDL mimics using liposome-encapsulated gold nanoparticles, in which the size and surface charge are independently controlled during synthesis. Here we examine the effects of lipid composition on zeta potential and electrophoretic mobility of LDL mimics. Using these mimics, we explored the effect of the lipid coating on the nanoparticles including anionic lipids and oxidized lipids. Dynamic light scattering was used to determine the size of the mimics and gel electrophoresis was used to measure the mobility and calculate zeta potential. The charge of the lipid coating influenced the mobility and we anticipate this will influence how the mimics interacts with proteins.
Best Practices in Student Section Participation and Professional Development
Authors: Jones Mary Kathryn , Dunn Kelsey N. , Hershman Jill R. , Pike Alston H. , Johnson Sarah E. , Todd Beth A.
Published: August 2012

ASME student sections have a strong tradition of serving the needs of undergraduate students at universities across the country and around the globe. Similar to senior sections, student sections can learn from one another by sharing best practices. This paper describes best practices in four areas of student section programming: 1) membership, 2) STEM outreach, 3) section leadership development, and 4) inclusion of graduate students. Through these and other best practices, student sections can remain effective in their role as a partner in workforce development.
Can We Rescue Thermal Wall Shear Stress Sensing?
Authors: Assadian Elsa , Bhiladvala Rustom B.
Published: August 2012

The use of single flush-mounted thin-films for thermal sensing of wall shear stress fluctuations in turbulent flows has seen a decline, in spite of their non-intrusiveness, and the availability of microfabrication technologies to create very small films. The limitations of such single-element sensors are quite severe—their spatial resolution is not determined by their size alone, but modified by substrate heat conduction which creates variations in the effective sensor size (heat exchange area), dependent on strength and timescale of the fluctuations. Here a two-element design is investigated—with the hot-film sensor element surrounded by an electrically isolated guard heater film maintained at the same temperature as the sensor, but controlled by a separate anemometer circuit. Numerical studies are used to examine such guard heater designs over a range of shear stress values. The results show that if the sensor film center-location is biased towards the downstream end (75% and 65% of guard-heater length for water and air, respectively), with an appropriately-sized guard heater, 95% of the total heat generated in the sensing film can be transferred directly to the fluid, for strong turbulent fluctuations (Peclet number Pe > 8000) when the working fluid is water.