bluuebunny/crossref_metadata_2025 huggingface dataset:
Adsorption Cooling With Multi-Stage Desiccant Processes
Authors: Huang Chen-Kang
Published: April 2014

For traditional adsorption cooling systems using silica-gel-like desiccant wheels, the moisture is removed from the air and stored in the desiccant wheels. The subsequent reactivation process is to dry the wheel by blowing hot air. The moisture is added to the dried air to take the advantage of evaporative cooling. Currently, the two processes are performed on the different sections of a wheel. However, the temperature of the reactivated part will be higher, and the residual heat will be dissipated into the air-conditioning space. Some researchers have reported to add another section to cool down the regenerative part. Unfortunately, the addition of cooling section decreases the working durations of other two sections.

In this study, a novel desiccant-evaporative cooling process is proposed. The wheel is now stationary. Fans and air doors were designed to adjust various air flows to pass through the wheel to perform the dehumidifying, reactivation, and cooling inside the wheel. Most importantly, for each period, the desiccant wheel was used only to dehumidify, reactivate, or cool down. The air to cool the desiccant wheel was released outside, so no residual heat went to the air-conditioning space. The outdoor air was acquired to be heated and reactivate the desiccant wheel. The indoor was used to cool the wheel to achieve better cooling effects.

An experimental prototype was designed and established. The air could be directed through the desiccant wheel. A controller was installed. The duration of the dehumidifying, reactivation, and cooling process could be set on the panel. The evaporative cooling process was performed by ten ultrasonic humidifiers. The hot air was from a liquid-to-air heat exchanger, and the hot water can be from a solar heater or any waste heat sources.

Optimized sets of period durations were suggested. The criteria to end each process have been proposed for future automation. It is shown that the novel design is able to deliver cooler air. Although the cool air output is currently intermittent, a solution has been figured out and will be improved soon.
Applying an Energy-Based Fatigue Life Prediction Method to Unnotched and Notched Al6061-T6 Specimen
Authors: Nesaei Sepehr , Letcher Todd , Delfanian Fereidoon
Published: April 2014

There is a strong relationship between fracture mechanics and fatigue. Recently, an energy-based fatigue life prediction method has been studied as a method to quickly, but still accurately determine an SN curve for new materials. In the development of this energy-based fatigue life prediction theory, efforts have concentrated on monitoring stress/strain hysteresis loops only to make life predictions. Thus far, no attempts have been made to link knowledge of fracture mechanics to advances in the energy-based fatigue lifing theory. In this study, notched and unnotched AL6061-T6 flat specimens were fatigued with fatigue monitored by an extensometer. In order to prevent from buckling during hysteresis strain loops, R = −0.5 stress ratio was used. In addition, efforts will concentrate in the low cycle fatigue (LCF) region to support future works on monitoring crack length in fracture mechanics investigation. The goal of this study is to understand how specimens behave in the context of the energy-based fatigue life theory when notches/cracks are present.
A Study on the Efficiency of Bicycle Hub Gears
Authors: Casteel Elizabeth A. , Archibald Mark
Published: April 2014

This study experimentally measured the efficiency of new generation bicycle hub gears. Since efficiency of bicycle drivetrains can be very close to 100% and vary by small amounts between gears bias errors and measurement accuracy must be identified and controlled. For this study an ergometer frame was altered to support research test equipment. A 1 HP motor and gearbox were used to drive the crankshaft. The hubs were attached directly to the steel flywheel using shortened bicycle spokes, eliminating extra chains or drive components. This setup minimizes measurement uncertainty in the drivetrain. Force-transducers were used to measure the motor and flywheel torque, and two magnetic reed switches were used to measure the speed of the motor and flywheel. Efficiency for each individual gear in each hub was calculated for 14 different power speed combinations. The efficiency of each gear was plotted against flywheel Torque, and an exponential model was fit to the data. This model accounts for known variations in efficiency with power and speed, and provides insight into the torque-speed-efficiency relationship. Four internally-geared hubs were measured and compared with a single speed direct drive train and a belt drive. The internal planetary gear hubs measured were the Shimano Alfine 11, Rohloff 500/14 Speedhub, SRAM Dual-Drive, and the Sturmey Archer X-RK8(W). In addition a single-speed direct chain drive, a single-speed belt drive, and a 7-speed derailleur system were measured. The efficiency of the Shimano Alfine ranged from 90.4% to 96.6%. The efficiency of the Rohloff speed hub ranged from 95.8% to 99.5%. The efficiency of the Sturmey Archer hub ranged from 84.6% to 99.8%. The efficiency of the single speed chain drive was found to be 99.71% and the belt drive 98.0%. The efficiency of the 7-speed derailleur ranged from 97.7% to 99.4%. These values found for efficiency are comparable to other studies.
Design and Operation of a Hybrid CCHP System Including PV-Wind Devices
Authors: Wang J. L. , Wu J. Y. , Zheng C. Y.
Published: April 2014

CCHP systems based on internal combustion engines have been widely accepted as efficient distributed energy resources systems. CCHP systems can be efficient mainly because that the waste heat of engines can be recovered and used. If the waste heat is not used, CCHP systems may not be beneficial choices. PV-wind systems can generate electricity without fuel consumption, but the electric output depends on the weather, which is not reliable. A PV-wind system can be integrated into a CCHP system to form a higher efficient energy system. Actually, a hybrid energy system based on PV-wind devices and internal combustion engines has been studied by many researchers. But the waste heat of the engine is seldom considered in the previous work. Researches show that, 20∼30% energy can be converted into electricity by a small size engine while more than 70% is released. If the waste heat is not recovered, the system cannot reach a high efficiency. This work aims to analyze a hybrid CCHP system with PV-wind devices. Internal combustion engines are the prime movers whose waste heat is recovered for house heating or driving absorption chillers. PV-wind devices are added to reduce the fuel consumption and total cost. The optimal design method and optimal operation strategy are proposed basing on hourly analyses. Influences of the device cost and fuel price on the optimal dispatch strategies are discussed. Results show that all of the excess energy from the PV-wind system is not worth being stored by the battery. The hybrid CCHP system can be more economical and higher efficient in the studied case.
A Distributed Source, Finite Absorption Model of a Pulsed Laser Diffusivity Measurement System
Authors: Hall James B. , Jones Matthew R. , LeFevre Jeremy , Terrill Trevor J.
Published: April 2014

Thermal diffusivity is a thermophysical property that quantifies the ratio of the rate at which heat is conducted through a material to the amount of energy stored in a material. The pulsed laser diffusion (PLD) method is a widely used technique for measuring thermal diffusivities of materials. This technique is based on the fact that the diffusivity of a sample may be inferred from measurement of the time-dependent temperature profile at a point on the surface of a sample that has been exposed to a pulse of radiant energy from a laser or flash lamp. The standard approach to PLD is based on a simple model that produces an explicit relationship between the diffusivity and the time required for the temperature of the sample surface to reach a specified fraction of the peak temperature. However, the standard approach is based on idealizations that are difficult to achieve in practice, so models that represent a PLD measurement system with greater fidelity are desired.

Assessment of the impact of the approximations made in the development of the standard approach showed that neglect of the spatial and temporal variations of the input power leads to significant errors in measurement of the thermal diffusivity. The objective of this paper is to present the Distributed Source Finite Absorption model which represents the spatial and temporal variations in the pulse with greater fidelity.

The cost of the increased fidelity is an increase in the complexity of the algorithm used to determine values of the thermal diffusivity. A simple relationship between an easily determined characteristic of the measured temperature profile and the thermal diffusivity does not exist. Therefore, a new method of extracting values from measured time dependent-temperature profiles based on a genetic algorithm and on reduced order modeling has been developed. This paper also presents a numerical verification of this proposed new method for measuring the thermal diffusivity.
Optimization Methodology for an Automotive Composite Hood
Authors: Lazzarini Alberto , Valgimigli Alessandro , Baldini Andrea , Dolcini Enrico , Sangermano Stefano
Published: April 2014

The current emissions regulations lead car manufacturers to look carefully for weight reduction. In the automotive industry the classic trial-and-error approach to design is becoming inadequate and techniques based on optimization are necessary to improve the design process. In this study a methodology to design a sport-car front hood is proposed. The process carried out could also be extended to car components characterised by a similar configuration.

Starting from the geometry of the actual part, a design volume has been defined. The first step consists of a topology optimization performed considering the material as isotropic (aluminium properties): the output is a rough structure which accomplishes all the imposed targets. The interpretation of the topology results brings to a re-design phase aimed at realising a feasible component.

The subsequent optimization step is dedicated to composite material structures and acts on the component plybook, varying thickness and orientation of each ply to find the best solution complying with targets. Finally, the component has to be reviewed from a technological point of view in order to be virtually delivered and to proceed with the prototype phase.
Design and Fabrication of Lunar Dust Excavator Robot
Authors: Rumi Md. Jalal Uddin , Salam Md. Abdus , Ebna Hai Bhuiyan Shameem Mahmood
Published: April 2014

Lunar rover has become an important topic in recent years. Scientists are always searching the existence of lives as well as trying to create a suitable environment for human living in other planets. But for man it is difficult to collect information or investigate the new environment due to adverse environmental conditions. As an alternative a robot can be designed to sustain this adverse environmental situation for collecting necessary information or investigation purposes. So a robot, capable of collecting lunar dust can be very helpful for environmental analysis of moon at a greater extent. In such a situation this paper presents a general framework for building a Robot for collecting lunar dust, its motion control, lifting the dust, and depositing dust in reservoir. The framework is instantiated to compute the requirements including power, networking, mechanical controlling, and electro mechanical interfacing. The Robot has been systematically fabricated by local components and tested for operational results in similar artificial environment as on the Moon.
Meshless Local Petrov-Galerkin Method for Heat Transfer Analysis
Authors: Rao Singiresu S.
Published: April 2014

A meshless local Petrov-Galerkin (MLPG) method is proposed to obtain the numerical solution of nonlinear heat transfer problems. The moving least squares scheme is generalized, to construct the field variable and its derivative continuously over the entire domain. The essential boundary conditions are enforced by the direct scheme. The radiation heat transfer coefficient is defined, and the nonlinear boundary value problem is solved as a sequence of linear problems each time updating the radiation heat transfer coefficient. The matrix formulation is used to drive the equations for a 3 dimensional nonlinear coupled radiation heat transfer problem. By using the MPLG method, along with the linearization of the nonlinear radiation problem, a new numerical approach is proposed to find the solution of the coupled heat transfer problem. A numerical study of the dimensionless size parameters for the quadrature and support domains is conducted to find the most appropriate values to ensure convergence of the nodal temperatures to the correct values quickly. Numerical examples are presented to illustrate the applicability and effectiveness of the proposed methodology for the solution of heat transfer problems involving radiation with different types of boundary conditions. In each case, the results obtained using the MLPG method are compared with those given by the FEM method for validation of the results.
Simultaneous Tracking of Vocal Fold Superior Surface Motion and Glottal Jet Dynamics
Authors: Nielson Joseph R. , Daily David J. , Truscott Tadd T. , Luegmair Georg , Döllinger Michael , Thomson Scott L.
Published: April 2014

Synthetic aperture particle image velocimetry is used with an excised human vocal fold model to study the airflow between the vocal folds during voice production. A whole field, time-resolved, 3D description of the flow is presented over multiple cycles of vocal fold oscillations. The 3D flow data are synchronized with a 3D reconstruction of the superior surface of the vocal folds and with the subglottal pressure signal.
Vibration Analysis and Measurement in Knee Ankle Foot Orthosis for Both Metal and Plastic KAFO Type
Authors: Takhakh Ayad M. , Kadhim Fahad M. , Chiad Jumaa S.
Published: April 2014

A standard knee-ankle-foot orthosis (KAFO) is typically prescribed to support the limb during locomotion, during which (KAFO) is used for people with isolated quadriceps weakness or paralysis. In this paper the measurement applied on girl undergoing palsy children in her left leg as a case study. The first pathological concern is of age, weight, length and the residual palsy limb of 30 years old, 59kg, 156 cm, and 76 cm respectively, while the second test done is on man suffering flexion knee and shorten left leg due to injection by a needle in a wrong position when he was a child. The pathological concern is of age, weight, length and the residual defect limb of 35years, 82kg, 172 cm, and 80 cm respectively. This work involves two major parts: the first of which is the experimental part to measure the ground reaction force for both healthy and intake legs. The interface pressure between leg and calf part is measured for twelve points covering the total KAFO surface area, while the vibration data (velocity, acceleration and frequency) are measured at the last stage for the patient at different positions during the gait cycle. The second part is the numerical part during which stresses is calculated using ANSYS software for two cases, the first one is calculating stresses due to IP loading condition, while the second is calculating stresses due to the harmonic and spectrum vibration type. The above procedures were used for two types of KAFO, the first one is for metal-metal KAFO type and the second is for the plastic-metal KAFO type. The result shows that the GRF for the healthy person limb is greater than that of the intake person limb in about (17 %) while the healthy limb has GRF lesser than that of the intake limb for the same person in (2.2%). The Maximum IP is recorded in the posterior regions in the thigh part with (51Kpa). The result shows that the maximum Vibration data is in the sensing position at the knee on (8.5 and 5.9)for acceleration and frequency respectively at knee region for the plastic-metal KAFO type. Using plastic-metal KAFO type also leads to reduce the vibration data on (6.4% and 26%) for both acceleration and frequency respectively at thigh region.
Concurrent Multiple-Time-Scale Simulations With Improved Numerical Dissipation for Structural Dynamics
Authors: Ruparel Tejas , Eskandarian Azim , Lee James
Published: April 2014

Work presented in this paper describes the formulation for implementation of a concurrent multiple-time-scale integration method with improved numerical dissipation capabilities. This approach generalizes the previous Multiple Grid and Multiple Time-Scale (MGMT) Method [1] implemented for the Newmark family of algorithms. The framework is largely based upon the fundamental principles of Lagrange multipliers used to enforce workless nonholonomic constraints and Domain Decomposition Methods (DDM) to obtain coupled equations of motion for distinct regions of a continuous domain. These methods when combined together systematically yield constraint forces that not only ensure conservation of energy but also enforce continuity of velocities across the interfaces. Multiple grid connections between (non-conforming) sub-domains are handled using Mortar elements whereas coupled multiple-time-scale equations are derived for the Generalized-α Method [2]. We show that MGMT Method can be easily extended to incorporate the Generalized-α family of time integration algorithms, hence allowing selective discretization in space and time along with controlled numerical dissipation for distinct grids. We also show that interface energy across connecting sub-domains is identically zero, further assuring global energy balance and continuity of velocities across connecting sub-domains.
Static and Dynamic Analysis of Microcantilever Beam Under Electrical Loading Using Couple Stress Theory
Authors: Bashmal S.
Published: April 2014

This study presents an electro-mechanical analysis of a microcantilever beam considering the effect of size dependence and flexible supports. The energy expressions are derived using couple stress theory, while additional energy terms were added to represent the flexible boundaries and fringing fields. Both static and dynamic analyses are performed to show the coupled effect of flexible support, electrical voltage and mechanical loading on the static and dynamic performance of the microcantilever beam.
Semi-Rigid Helmet Rotation Measurement Using Linear Accelerometers
Authors: Juhas Brett D. , Wong Jessica M. , Boroumand Nicole J. , Rigby Paul H.
Published: April 2014

The number of sensors placed on warfighters’ personal protective equipment (PPE) continues to increase each year. It is important to be able to accurately measure the dynamic response of PPE in order to characterize new sensors that are meant to track warfighter movement. In an effort to help predict head motion, a method has been developed to accurately measure the angular and linear acceleration of a semi-rigid helmet using four triaxial linear accelerometers. This four-accelerometer array configuration is based on the 3-2-2-2 nine accelerometer package (NAP) method and was tailored to accurately measure the helmet response during impact and blast overpressure events. Method development and testing were performed using U.S. Army Advanced Combat Helmets. Since angular motion calculation using the NAP method requires orthogonal sensor placement, it was necessary to revise the standard NAP sensor configuration to account for the geometric constraints of a helmet. Modal analysis was performed to determine the locations of least vibration, and shock tube and drop tests were conducted to investigate helmet flex during impacts. Knowledge concerning the dominant vibration modes of the helmet guided accelerometer placement and helped mitigate the effects of sensor data oscillation on the calculated angular motion. Local helmet deformation strongly depends on the impact site; several accelerometer array configurations were developed to account for various impact directions. Linear accelerations were measured and angular accelerations were calculated for guided free drop and shock tube tests in the laboratory. In guided free drop tests, the helmet and headform were dropped onto an anvil at various velocities and were allowed to freely bounce after impact. In shock tube tests, the helmet and headform were allowed to swing freely when subjected to a high shock wave simulating an IED blast. The modified NAP method was able to accurately measure the linear and angular acceleration of the helmet for both types of tests. The angular motion calculation was validated using a high-speed video camera recording the helmet response at 10,000 frames per second. Results were also compared to angular rate sensors available on the market. It was determined that with a detailed understanding of a semi-rigid body’s vibration and proper placement of linear accelerometers, angular acceleration during high-shock impacts can be accurately calculated for semi-rigid, irregular shaped objects. This accelerometer placement method has been applied to several other military grade helmets and been used in models predicting head motion from helmet motion data.
Evaluation of Electro-Spun Tubular Scaffolds to Create an Anastomosis Using the CAM Assay
Authors: Orendain Adam , Carrasco Jose , Enikov Eniko T. , Peyman Gholam
Published: April 2014

Central retinal vein occlusion (CRVO) is a vascular disease characterized by thrombosis of the retinal veins that can eventually lead to ischemia. Ischemic CRVO can then cause macular degeneration and neovascular glaucoma causing partial to full blindness. In this study, we determined the feasibility of electrospinning tubular scaffolds for treating CRVO and vascular disease. Electrospinning was utilized to produce customizable scaffolds from nano-bers using collagen type I. Scaffolds were treated with glutaraldehyde, glycine, ethanol, UV light, and combinations of the treatments for the purpose cross-linking and to study their angiogenic effects. Structural properties of the scaffolds were analyzed with scanning electron micrsoscopy (SEM). Scaffolds were immobilized with human recombinant vascular endothelial growth factor (rhVEGF165) to investigate the drug-delivering abilities of the electrospun materials and as a method to produce vascularization. The chick chorioallantoic membrane (CAM) assay was used to examine the effects of VEGF immobilizations and to evaluate the feasibility of creating an anastomosis to treat CRVO. Collagen onplants (non-electrospun) and electrospun implants were made on day 10 of embryonic development. Findings show collagen loaded with rhVEGF165 had improved vasculature and pro-angiogenic properties. The present study suggests that collagen can immobilize and release growth factor, be electrospun to mimic the ultrastructure of native blood vessels, and holds promise for vascular tissue engineering.
Microstructural Analysis of Laser Micro-Welds Between Electrode Materials for Li-Ion Battery Applications
Authors: Mian A. , Taylor C. , Vijwani H. , Hartke K. , Mukhopadhyay S. , Dosser L.
Published: April 2014

Currently used ultrasonic welded joints for assembly and packaging of Li-Ion batteries have reliability concerns for automotive applications, as the battery is subjected to vibration and other mechanical loads. The sealing of the battery can is very critical for safety. Due to battery weld failures in recent years, the postal service has put ban on shipping Li-ion batteries via regular mail. A laser based alternative joining technology has the potential to offer robust, fast and cost-effective processing of Li-Ion batteries. Before the technology can be fully implemented, it is imperative to understand the effects of various process parameters on the robustness of the weld. In the present analysis, a preliminary study is performed to understand the effect of laser scanning speed on the micro-structural and physical characteristics of the materials in the weld area that ultimately affect the bond quality. Samples are created by welding aluminum and copper in lap shear configuration using a continuous wave fiber laser. Two sets of samples are created using a laser power of 225 W; however, the scanning speeds are 300 mm/s and 400 mm/s. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDAX) are performed in the weld area to understand the microstructural and physical characteristics of the joint that may have been affected by the processing parameters.
Silicon Carbide MEMS Capacitive Pressure Sensor for Harsh Environments
Authors: Chen Zhibang , Du Wei , Zhao Feng
Published: April 2014

In this paper, we investigated a new capacitive pressure sensor structure on a silicon carbide (SiC) platform for high sensitivity and harsh environment operation capability. The superior material properties of SiC ensure robustness of the new sensor to withstand large-scale pressure at high temperature and in chemical/biological medium. The sensor structure consists of a circular SiC diaphragm suspended by four arms over a SiC substrate, with design to enable diaphragm to deflect nearly uniformly with applied pressure. This configuration results in improved sensing properties. With high sensitivity and operation capability in hostile environment, this new pressure sensor is promising for use in a wide range of applications such as automotive, nuclear station, aerospace, and oil/gas exploration, etc.
Mechanical Effectiveness of Polyvinyl Alcohol/Polyvinyl Pyrrolidone (PVA/PVP) as an Intervertebral Disc Polymer
Authors: Azartash-Namin Kooroush , Azartash-Namin Zheila , Williams S. Ashton , Tran Khiet , Khandaker M.
Published: April 2014

The intervertebral disc is one of the body’s most vital structures. It provides support and enables six degree of freedom (6DOF) motions in the spine: flexion, extension, right and left lateral bending, compression, and axial rotation. When individuals suffer from degenerative disc disease, the nucleus pulposus deteriorates, causing a loss of articulation in the intervertebral disc. To address this problem, replacements for the nucleus pulposus can be used. The objective of this study was to evaluate a potential nucleus pulposus replacement consisting of a hydrogel polymer. The hydrogel was synthesized by physically cross-linking 95%-weight polyvinyl alcohol (PVA) and 5%-weight polyvinyl pyrrolidone (PVP). PVA and PVP were selected for the hydrogel implant due to the natural biocompatibility when the two are physically cross-linked. In order to evaluate the mechanical effectiveness of the hydrogel, a slider-crank mechanism was designed and constructed to create the 6DOF motions when interfaced with a Universal Mechanical Testing System. The viscoelastic properties of the polymer were obtained using a rheometer, which determined the elastic (G′) and viscous (G″) moduli of the PVA/PVP hydrogel polymer by calculating the complex shear modulus (G*) under low-frequency oscillating shear deformation. This allows for study of the viscoelastic performance of the isolated nucleus pulposus and hydrogel implant. The elastic modulus of the hydrogel was tested at parameters 5%, 10%, and 15% strain with results of 228.6 Pa, 988.8 Pa, and 1793 Pa, respectively. However, the elastic modulus tested for the natural bovine specimen at 5%, 10%, and 15% strain were 712.9 Pa, 522.1 Pa, and 363.3 Pa, respectively.
Simulation of Multiple Confined Impinging Jets on a Heated Plate Using the Lattice Boltzmann Method
Authors: Al Rmah Masoud A. , Mohamad Abdulmajeed A.
Published: April 2014

A laminar two-dimensional thermal-flow generated by multiple confined jets impinging on an isothermal plate is investigated numerically using the lattice Boltzmann method. The impinging plate is kept at a constant high temperature while a cold air is flowing through the jets. The effect of different parameters (Reynolds number (Re), and the ratio between the jets height (H) and jets width (W))on the hydrodynamics and thermal characteristics of the flow field is discussed. The Reynolds number is ranging from 50 to 400, and the (H/W) ratio is varying between 1 and 3W.
Design and Optimization of Free Piston Expander for Energy Harvesting
Authors: Champagne C. , Weiss L.
Published: April 2014

There is a growing opportunity and need for research that investigates alternate power sources. One such source is low temperature waste heat, or energy cast off to the environment as part of some larger process. Through the capture and use of this abundant energy source for power production, it is possible to enhance the overall operating efficiency of the larger system. This presents significant potential for sustainability increase and energy savings. One potential system that can operate from these sources is a low temperature, small-scale steam expander. Investigations of one such device called a Free Piston Expander (FPE) are presented in this work.

In final form, the FPE will be a MEMS based device capable of operation as part of a complete low temperature steam system. In this present study, a millimeter scale device is constructed and tested to yield insight into critical operational parameters for future microfabricated designs. Construction of this testbed device is via concentric copper tubing, allowing an effective baseline study of these determining parameters.

Parameters studied include device cross sectional area and shape as well as operational pressure. Once consistent parameters are determined, three separate variations of circular FPE design are further tested. These FPEs are designed to either constrain piston rotation or allow for rotational freedom during operation. Testing is performed on these devices for consistency in piston motion. Piston motion is characterized based on a single expansion and reaction of the piston.
Parametric Multibody Modeling of Anthropomorphic Robot to Predict Joint Compliance Influence on End Effector Positioning
Authors: Baglioni Stefano , Cianetti Filippo , Braccesi Claudio , Landi Luca
Published: April 2014

Nowadays, in the field of robotic, one of the most important objectives is to reduce robot error positioning and improve its dynamic behaviour. One of the main source of error in end effector positioning is due to the joint compliance: robot joint components under operating conditions can be deformed as a function of their stiffness/damping properties. Generally, for industrial robots, harmonic drive gearings are used, their principal characteristics are high transmission ratio and law weight, on the other hand, to realize high transmission ratio, harmonic drive gearings work on inner gear elastic deformation, conferring to the robot joints an excessive compliance that, in some robot applications, cannot be neglected. In this research activity multibody modelling and simulation approach has been used to analyse joint compliance influence on robot position accuracy. The principal aim of this work was the formulation of a modelling procedure that starting from classical robots modelling approach (i.e. Denavit Hartenberg) defines an universal database and a parametric modelling procedure that allows the designer to use any multibody commercial codes to analyse anthropomorphic robots considering or not the compliance effect. All the procedure was developed and managed into a numerical code environment (Matlab/Simulink).

An example of commercial anthropomorphic robot was considered by assuming its principal kinematic and dynamic characteristics. Parametric models of the robot have been developed in two different multibody modelling environments (Simmechanics, Adams/View). Moreover the models structure has been built in order to control the robot movements both in motion (open loop) or in force (closed loop). In this case they are interfaced with Simulink code in a so called co-simulation approach that allows to developed a generic control system and test it by using one or more models, less or more refined.
Numerical Modeling of Fluidic Pumping in Micronetworks of Plants
Authors: Sze Tsun-kay Jackie , Liu Jin , Dutta Prashanta
Published: April 2014

Plant transport mechanisms are of interest in developing micropump for engineering devices. We present a two-dimensional phloem loading and transport model incorporating protein level mechanics with cellular level fluid mechanics. Governing Navier-Stokes, continuity, and Nernst-Planck equations are numerically solved to determine fluid flow and sugar transport. Phloem loading mechanics for active loading is incorporated through a six-state proton sucrose pump kinetic model. The influence of binding rates constants, concentrations, and membrane electrical potential differences on resulting sucrose transport is studied. Numerical results show that increasing rates of the sucrose transporter will noticeably increase outflow. Simulation result also show that a lower leaf sieve sucrose concentration improves outflow. In addition, a more negative membrane electrical potential difference will increase outflow. This numerical model offers insight on parameters that may be significant for implementing plant transport mechanisms in microfluidic devices.
Investigation of Crashworthiness of Structural Composite Components in Vehicle Crash Test Simulations
Authors: Park Chung-Kyu , Kan Cing-Dao (Steve) , Hollowell William Thomas
Published: April 2014

A finite element (FE) model of a baseline and a light-weighted 2007 Chevrolet Silverado, which is a body-on-frame pickup truck, was utilized to evaluate the safety performance of a plastics and composite intensive vehicle (PCIV). By lightweighting steel components in the Silverado using advanced plastics and composites, the original vehicle weight, 2,307 kg, was reduced to 1,874 kg, which is about a 19.0% decrease. As a result, the light-weighted vehicle contains about 442 kg of plastic and composites, which represents about 23.6% of the total weight of the light-weight vehicle. These light-weighted components includes not only non-structural components, but also structural and semi-structural components, such as the bumpers, front-end modules, fenders, door impact beams, A- and B-pillar reinforcements, and ladder frame. The crash performance of these structural components was evaluated by the simulations of four vehicle crash tests: (1) frontal New Car Assessment Program (NCAP) test, (2) frontal Insurance Institute for Highway Safety (IIHS) offset test, (3) side NCAP test, and (4) Federal Motor Vehicle Safety Standards (FMVSS) 216 roof test. The results show that structural composite components in a vehicle are able to provide equivalent crashworthiness performance to the steel components in frontal and side crash and roof testing configurations.
Cooling Systems for Power Plants in an Energy-Water Nexus Era
Authors: Wong Kaufui V. , Johnston James
Published: April 2014

Potable water is becoming scarce in many areas of the planet as the human population pushes past 7 billion. There is an increasing need for electric power since electricity is essential for modern development and progress.

Traditionally, condenser cooling systems for power plants use seawater or freshwater in conjunction with cooling tower technology. Seawater is used in plants near the sea or ocean, and seawater condenser cooling systems are typically open systems. More recently, air-cooling has been implemented and undergoing evaluations. Predictably, during the summer season in hot, semi-desert and desert areas, air-cooling would not prove very efficient. Ironically, these areas would require the most fresh, potable water if the population and/or population density is large. The need for additional power generation units to satisfy consumer demands, and hence more cooling capacities, creates a problem for utilities.

The current work researches the feasibility of using seawater cooling systems in the USA that are far from the sea. Five such locations have been identified as possibilities. Such a system has proven successful in South Florida. This system utilizes a series of cooling canals, used to dissipate the condenser heat to the surroundings. Relevant statistics of such a canal include water flow rate, total capacity, and MW of generators (both fossil-fueled and nuclear steam generators) the system is designed to cool. Additional statistics include the possible need to top-up (both amount and frequency of water required to maintain canal surface levels) or whether local natural rain water is adequate to replace evaporation and loss. Logistical information includes the estimated size of land required to accommodate the cooling canals. In estimating the canal system size and concomitantly the land required in other parts of the country, there is the tacit assumption that the thermal capacity of the surrounding land is about the same, and that the thermal conductivities of the different types of soil, and the heat transfer coefficients between the seawater and the canal are similar.
Quality of Reamed Surface Using Serrated Blades as Compared to a Conventional Acetabular Reamer
Authors: Levasseur Annie , Ménard Jérémie , Songmené Victor , Fernandes Julio , Petit Yvan
Published: April 2014

Background: Hip arthroplasty requires the preparation of the acetabular cavity to allow a proper contact between the bone and the implant. It is essential to allow osseointegration and long-term stability of the implant. The aim of this study was to conduct experimental testing to evaluate the quality of reamed surfaces using a serrated blade acetabular reamer as compared to a conventional rasp reamer.

Method of Approach: Reaming tests were performed on a computerized numerical control tools machine at a rotational speed of 250 rpm and 3 different penetration speeds: 0.20 mm/s, 0.55 mm/s and 0.90 mm/s. For each reamer, a complete semi-hemispherical hole was perforated in 7 polyurethane samples. The reamed surfaces were digitized with a three-dimensional high resolution (40 μm) self-positioning laser scanner to carry out a quantitative analysis of the surface quality.

Results: Results demonstrated that the cutting edge and the penetration speed influence the quality of the reamed surface. The serrated blade was found to reduce surface irregularities (ranging between 0.19 mm to 0.21 mm for the conventional rasp and between 0.07 mm and 0.12 mm for the serrated blades), and to reduce inaccuracies on the reamed cavity diameter (0.13 mm ± 0.05mm for the rasps and 0.06 mm ± 0.03mm for the serrated blade).

Conclusions: The use of such tool by the surgeon may influence the stability of the acetabular implant and reduce the risks of revision surgery.
Vision-Based Trajectory Tracking Approach for Mobile Platforms in 3D World Using 2D Image Space
Authors: Dinc Semih , Fahimi Farbod , Aygun Ramazan
Published: April 2014

Vision-based target following using a camera system mounted on a mobile platform has been a challenging problem. A scenario is assumed in which the platform/camera system is required to have a desired trajectory for relative position and orientation (pose) with respect to a target object. It is assumed that the actual pose of mobile platform with respect to the target is not measured by a Global Positioning System (GPS) and/or an Inertial Measurement Unit (IMU). For trajectory tracking feedback control, the error in the relative pose of the mobile platform with respect to the target needs to be computed. In the absence of GPS/IMU signals, the error in relative pose must be calculated using a vision-based approach. In this paper, we introduce a fast alternative vision-based approach for real-time calculation of the error in the relative pose of the mobile platform and the target. The proposed vision-based tracking approach is called PIVOT: Positioning and Orienting Using Vision-Based Object Tracking. The PIVOT system calculates the pose errors of the mobile platform in the 3D world based on a 2D image space. The only information required is “the desired 3D pose” and the coordinates of selected feature points on the target in order to track properly. The PIVOT forms a desired target image, compares it with the current target image and outputs the required 3D translation and rotation of the platform/camera to correct the image error. The required 3D translation and rotation of the platform/camera to correct the image error are fed to a feedback controller to drive the mobile platform in the direction that corrects the image error. When the image error is vanished, the mobile platform is moving on its desired trajectory. We have performed a set of experiments with the proposed PIVOT approach to show the effectiveness of the theoretical framework. According to the simulation results, PIVOT provides accurate pose errors for all test cases. The formulation of the approach is general, such that it can be applied to mobile platforms that move in 3D as well as 2D. Our first simulated and experimental tests will be on a mobile robot.
Lead Zirconate Titanate Nanotube Composite for Ultrasound Transducer Application
Authors: Zhang Guitao , Xu Weihe , Shi Yong
Published: April 2014

Lead Zirconate Titanate (PbZr1−xTixO3, PZT) is a high performance piezoelectric material which is widely used for making ultrasound transducers. However, pure PZT suffered from high acoustic impedance and crosstalk effect, which deteriorate their performances. To solve these problems, people developed micro fiber PZT composite. As restricted by the fabrication method, like dicing, the size of PZT micro fibers are usually on the order of 10s micros. In this paper, we are going to introduce a PZT nanotube composite, in which the size of active material is on the order of nanometers. To fabricate the PZT nanotube composite, we used a template assistant method. First an anodic aluminum oxide (AAO) template was made by two step anodic process. Then PZT nanotube composite was made by wetting the AAO template with PZT sol-gel. Following, top and bottom electrodes were made by silver paste. After fabrication, hysteresis loops were measured to verify the piezoelectricity property of this nanotube composite. Then the impedance of the composite transducer was measured by a network analyzer. Resonant frequency of the transducer was found by the impedance data. This nanotube composite based transducer could theoretically reduce or even eliminate the crosstalk effect, since the diameter of nanotube is much smaller than half wave length of ultrasound. So an improved performance of PZT nanotube composite based ultrasound transducer could be expected.
Influences of Grit Shape and Cutting Edge on Material Removal Mechanism of a Single Abrasive in Flexible Robotic Grinding
Authors: Tahvilian Amir Masoud , Champliaud Henri , Liu Zhaoheng , Hazel Bruce
Published: April 2014

A flexible robotic grinding system has been used for in situ maintenance of large hydro turbine runners by Hydro-Quebec. Field trials for more than 20 years have proven the reliability and efficiency of the technology for hydropower equipment maintenance and repair. This portable robot named SCOMPI, is developed by IREQ, Research Institute of Hydro-Quebec and can perform high material removal rate grinding on hardly accessible areas of turbine runner blades. Due to the light weight and low rigidity of the robot, traditional position control of conventional grinding is not applicable in this process. Instead a hybrid force/position controller is employed to ensure the accuracy of the predefined material removal rate. Therefore, having a good force model for a specific removal rate is a prerequisite for controlling the grinding task. Understanding the grinding process as the cutting action of several single grits participating in the material removal process provides an insight to predict the needed forces.

This paper presents an investigation of the effects of grits shape on cutting forces in single abrasive cutting mechanism during high removal rate grinding by SCOMPI robot. A three-dimensional finite element model is developed to simulate the chip formation process with different grit shapes. Thermal results from our previous study of temperature distribution in the contact zone for this special robotic grinding are imposed to the un-deformed chips. Then, Johnson-Cook plasticity model is employed to investigate effects of hardening and thermal softening of work piece material in cutting forces. It is also found that, rake angle and cutting edges of the grit can have significant effects on the cutting and normal forces.
Effect of Valproic Acid on Cell Proliferation of Wharton’s Jelly MSC in PCL Nanofiber Scaffolds
Authors: Dougherty John , Schaefer Emily , Niemeier Ryan , Koch Erin , Cady Craig , Nair Kalyani
Published: April 2014

The field of tissue engineering and regenerative medicine is an interdisciplinary field that applies the principles of engineering and life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function or a whole organ. The process involves seeding cells onto biocompatible scaffolds that temporarily act as a supporting structure for cells to attach and grow. Scaffolds for tissue regeneration must present a viable microenvironment for the living cells to adhere, proliferate, and exhibit the necessary tissue function. Electrospinning is an emerging area where polymeric fibers can be fabricated in the micro-nano scale. The flexibility of this process allows for including a wide array of synthetic and natural biocompatible polymers in the scaffold composition, inclusion of bioactive molecules (e.g. DNA, proteins) for enhancing therapeutic applications, and ability to control material and mechanical properties via the electrospinning process — all advantageous parameters that contribute to the promise of utilizing electrospun scaffolds in tissue repair. Biocompatible materials, such as polycaprolactone (PCL), have been used extensively to fabricate scaffolds using electrospinning technique, to study cell compatibility and to evaluate cell functionality for nerve tissue engineering applications. The objective of this study is to quantify the effects of the addition of valproic acid to PCL nanofiber scaffolds created through the electrospinning process with regards to cell proliferation. Valproic acid is a commonly used therapeutic drug for the treatment of epilepsy and bipolar disorder. To determine the effects of the presence of valproic acid (VA), Wharton’s jelly mesenchymal stem cells (MSC) are seeded to the two scaffolds. Wharton’s jelly MSC are multipotent adult stem cells present in the umbilical cord and drawn from their matrix [1,2,3]. These stem cells have renowned ability for use in cell therapy and organ regeneration. This study tests the hypothesis that the presence of valproic acid in PCL nanofiber scaffolds will enhance cell proliferation. Structural and morphological characterization of the scaffolds is also carried out. Fiber diameter and tensile properties of the scaffolds with and without valproic acid are also observed. Such studies will enable us to understand the effects of drugs such as valproic acid on stem cells and will aid in designing scaffolds for applications in nerve regeneration.