bluuebunny/crossref_metadata_2025 huggingface dataset:
Process Design for the Flow of Ethanol Chemical Vapor Deposition Grown Vertically Aligned Single Walled Carbon Nanotubes
Authors: Abuhimd Hatem , Zeid Abe , Jung Yung Joon , Kamarthi Sagar
Published: October 2013

Carbon nanotubes (CNTs) have received much attention from both the scientific and industrial communities due to their structural properties and unique morphology. There has also been growing interest in vertically aligned single walled carbon nanotubes (VA-SWNTs) because of their suitability for building devices such as solar cells and nanomembrane. Various methods including chemical vapor deposition (CVD) have been developed for growing VA-SWNTs. Among them is alcohol catalytic CVD which is well known for its economic viability, comprehensive substrates selectivity and good yield of VA-SWNTs. This work studies the length assurance of VA-SWNTs growth by an experimental design and an artificial neural network (ANN) metamodel. Process analysis shows that the interaction between gas flow rate and growth time are the most significant input factors. In addition, with high probability flow rate less than 150 sccm and a growth time of 20 minutes are suitable for the repeatability of medium length VA-SWNTs.
To Control Interface Shape and to Reduce Thermal Stress During Cz-Growth of Sapphire Single Crystal
Authors: Fang H. S. , Zheng L. L. , Zhang Q. J. , Wang S. , Pan Y. Y.
Published: October 2013

A global modeling is conducted to predict heat transfer, fluid flow, the shape of solid/liquid (S/L) interface, and electromagnetic field during a Radio Frequency (RF)-heated Cz-growth of sapphire single crystal process. The relationships between the convexity of the S/L interface and furnace design/growth parameters are established. Thermal stress distributions of each case are modeled, and the one with the least level of the maximum von Mises stress is proposed. Specific efforts are further made to achieve the flat S/L shape by modifying the furnace design. It is found that a flat interface is crucial for the reduction of thermal stress. Therefore, stress-related defects in sapphire single crystals grown by Czochralski (Cz) method could be optimized from the discussion.
Trigonometric Collocation for Computation of Steady State Responses of Cracked Structures
Authors: Bakeer Bakeer , Shiryayev Oleg , Tahir Ammaar
Published: October 2013

Development of vibration-based structural health monitoring techniques requires the use of various computational methods to predict dynamic responses of damaged structures. The method described in this work can be used for prediction of steady state harmonic responses for structures with fatigue cracks and may have several advantages over alternative techniques.

The method appears to be relatively easy to implement and computationally inexpensive. The steady state response of the system at a given number of time points distributed over one vibration period is represented in terms of Fourier series containing higher frequency harmonics. Equations of motion are formulated in the form that allows for easy computation of Fourier coefficients for all terms in the series. Iterative procedure is used for determining the time of stiffness change in order to capture bilinear dynamic behavior. We present results of initial investigation by applying the method to a model of a cantilever beam with a crack.
Analysis of Band Structures of Nanosized Phononic Crystals by Nonlocal Elastic Theory
Authors: Wang Yue-Sheng , Chen A-Li
Published: October 2013

Based on the nonlocal elastic continuum theory, the band structures of the nano-sized layered phononic crystals are analyzed by computing the localization factors and dispersion curves. Detailed calculations are performed for a nanosized HfO2–ZrO2 periodic layer stack. The size-effect on the band structures is examined. It is found that the nonlocal elastic continuum solution deviates from the classical elastic continuum theory and finally approaches the first-principle result as the thickness of each individual layer decreases. Due to the size-effect, there exists a cut-off frequency beyond which the waves cannot propagate through the system.
Thermal Modeling of High Temperature Energy Storage Using Encapsulated Phase Change Materials
Authors: Elmozughi Ali F. , Zhao Weihuan , Neti Sudhakar , Oztekin Alparslan
Published: October 2013

Transient heat transfer analysis is conducted to investigate high temperature energy storage using encapsulated phase change materials (EPCMs) for concentrated solar power applications. The phase change material considered is the eutectic mixture of NaCl-MgCl2 (57 mole% NaCl and 43 mole% MgCl2) encapsulated by stainless steel in a cylindrical shaped capsule (or tube). Energy storage into EPCM and energy retrieval from EPCM is simulated for various flow conditions of the heat transfer fluid. Heat storage/retrieval times are determined from numerical simulations for various sizes of capsules and flow conditions by an accurate modeling of propagating solid/liquid interface. Numerical simulations are conducted by employing a front tracking method and the enthalpy–porosity approach. A two-dimensional horizontally placed cylindrical shaped EPCM capsule is considered in simulations using gas (air) and liquid (VP1-Therminol) as heat transfer fluids. The results predicted by the front tracking method agree well with those predicted by the enthalpy–porosity method. It is illustrated by the present work that enthalpy–porosity method can be employed to simulate the modeling at the single capsule level and system level. System level storage unit is a thermocline that includes an arrangement of several EPCMs.
Measuring Model and Design of the Novel Loaded Over-Constrained Parallel Six-Component Force/Torque Sensor
Authors: Zhao Yanzhi , Lu Chao , Zhao Tieshi
Published: October 2013

Based on constrained screw type synthesis theory, a novel spacial over-constrained parallel six-component force/torque sensor mechanism which contains 12 SS branches was proposed. Then considering the branches flexible deformation, with the supplementary deformation coordination and physical constitutive constraint equations, structural balance equations were established respectively in six one-way measurement states. The stress and mode of the whole over-constrained parallel six-component force sensor structure scheme were analyzed with the Finite Element Method (FEM), and the analysis results were contrasted and conclused that theoretical calculations and Finite Element Analysis of conclusion were coincide.
Experimental Study on Dynamic Coeffcients of Water Lubricated High-Speed Hybrid Bearings With Stepped Recesses
Authors: Wang Lin , Xu Hua , Ma Shilei
Published: October 2013

In general, the oil-film forces can be characterized by linear oil-film coefficients of hydrodynamic bearing. This paper proposes an experimental method to recognize the dynamic coefficients of a water lubricated high-speed hybrid bearing with stepped recesses. A test rig is constructed and experimental data are acquired under different conditions. And the unbalance responses method is used to identify the dynamic coefficients of the hybrid bearing system. Comparisons are made to verify the validity and accuracy of the theoretical analysis. The influence of operating parameters, such as supply pressure and rotating speed, on the dynamic coefficients of the system is discussed. The results indicate that the dynamic coefficients increase with the rotating speed when the supply pressure is low.
Traction-Motor Power Ratio and Speed Trajectory Optimization for Power Split PHEVs Using Route Information
Authors: Vajedi Mahyar , Taghavipour Amir , Azad Nasser L.
Published: October 2013

Plug-in hybrid electric vehicles (PHEVs) are a promising option for future of transportation. They suggest better fuel economy and less emission compared to conventional HEVs. In this work, a method to find the optimum traction-motor power ratio (TMPR) and speed trajectory for a power-split PHEV is proposed in order to minimize the fuel consumption. The traveling path is divided into several segments. Each segment consists of acceleration, constant speed, and deceleration sections. Also, the route information, such as travel distance, traffic data, the maximum permissible speed, and road grade are known in each segment.

The results of simulation show a considerable reduction in the fuel consumption for different energy management strategies; up to 8% in CDCS, 12.9% in manual CDCS, and 18.2% in blended strategy, using the proposed optimum TMPR and speed trajectory.
Integration of Course Learning Outcomes With Program Assessment for ABET Accreditation
Authors: Duan Shanzhong (Shawn) , Bassett Kurt
Published: October 2013

This paper intends to discuss a course assessment procedure to link course learning outcomes to program outcomes for ABET accreditation requirements. ME 323 Vibrations is used as an example to demonstrate this course assessment procedure. The procedure begins with the development of course objectives and learning outcomes. Then course learning outcomes are directly mapped with the program outcomes. Mapped learning outcomes and program outcomes are integrated into the course syllabus, and shared with students. Students are required to read both of them as the first course assignment. Further, the course teaching contents and learning activities are developed according to the established course objectives. Achievements of students are evaluated according to a program assessment evaluation form. The current course evaluation results indicate that the approach provides a promising tool for ME course assessment per ABET requirements.
Measuring Elastic Strain Using Radon Transform-Based Image Processing for Tensile Testing
Authors: Ashry Ayman S. , Metwalli Sayed M.
Published: October 2013

Uncertainty in monitoring deformations of a planar surface has been among the major components that contribute to the overall positional error and thus must be minimized especially for small strains. This Study develops a Radon transform (RT)-based image processing for measuring elastic strain. A theoretical investigation is accomplished to propose a proper configuration of the marked lines and its in-between distance on the specimen surface. The method is applied to simulated strained image generated by MATLAB™ and verified using ASTM E83 for extensometer verification. In addition to measuring the axial and lateral strain of tensile testing, the Young’s modulus and Poisson’s ratio are measured. It demonstrates further that the integration of RT with cubic spline interpolation in detection of linear features enables high spatial resolution and less time of computation. Eventually, the method presented is insensitive to illumination variation and to in-plane rotation of specimen.
Modeling of Multifunctional Porous Tissue Scaffolds With Continuous Deposition Path Plan
Authors: Khoda A. K. M. B. , Ozbolat Ibrahim T. , Koc Bahattin
Published: October 2013

A novel modeling technique for porous tissue scaffolds with targeting the functionally gradient variational porosity with continuous material deposition planning has been proposed. To vary the porosity of the designed scaffold functionally, medial axis transformation is used. The medial axis of each layers of the scaffold is calculated and used as an internal feature. The medial axis is then used connected to the outer contour using an optimum matching. The desired pore size and hence the porosity have been achieved by discretizing the sub-regions along its peripheral direction based on the pore size while meeting the tissue scaffold design constraints. This would ensure the truly porous nature of the structure in every direction as well as controllable porosity with interconnected pores. Thus the desired controlled variational porosity along the scaffold architecture has been achieved with the combination of two geometrically oriented consecutive layers. A continuous, interconnected and optimized tool-path has been generated for successive layers for additive-manufacturing or solid free form fabrication process. The proposed methodology has been computationally implemented with illustrative examples. Furthermore, the designed example scaffolds with the desired pore size and porosity has been fabricated with an extrusion based bio-fabrication process.
Design of Remote Laboratory Experiments Using LabVIEW Web Services
Authors: Tumkor Serdar , Esche Sven K. , Chassapis Constantin
Published: October 2013

Laboratory experiments are an important and integral part of the learning experience for undergraduate engineering students. They help the students in getting hands-on experience and in better understanding theoretical concepts. In recent years, a significant number of remotely accessible experiments have been developed and integrated into engineering laboratory courses at many educational institutions worldwide. There exist several approaches and technologies for making experimental hardware accessible via the Internet.

This paper will discuss some of the available technologies and a specific method for acquiring data from experimental setups via LabVIEW Virtual Instruments over a network. As an example, a remote experimental apparatus that was developed by upgrading a commercially available air flow rig with remote control and monitoring capabilities is presented. This system is used in a junior-level mechanical engineering course on fluid mechanics. It enables the students to access the experimental setup via the Internet either in real-time or batch mode. For real-time use of the experimental setup, remote panels are used. These remote panels are exactly the same as those that would be used on a local on-site server. They can be run under LabVIEW’s Web server to be observed and controlled by the client via any Internet browser. For the batch-mode use of the experimental setup, on the other hand, simple HTML pages in conjunction with forms are used to generate experimental requests that are sent to the LabVIEW server. This server then places these experimental requests in a queue and executes the appropriate LabVIEW scripts on a first-come first-served basis. This paper will discuss and compare both methods for performing remote laboratory experiments.
Design of Artificial Neural Network Using Solar Inputs for Assessing Energy Consumption in a High Performance Academic Building
Authors: Sterman Michael , Baglione Melody
Published: October 2013

Artificial neural networks (ANNs) are a commonly used and effective method for estimating the outputs of nonlinear plants. In this paper, a neural network is used to estimate the electricity consumption of Cooper Union’s new high performance academic building at 41 Cooper Square. Although neural networks have been used for over 20 years to estimate municipal or regional energy consumption, extending their application to analyzing the energy consumption of individual buildings offers great potential. Because most existing ANN models are implemented over a municipal or regional scale, additional variables were considered as inputs to this model to account for factors specific to individual buildings. Depending on a building’s height and aspect ratio, the location of the sun can have a significant effect on heating and cooling loads. This paper analyzes the effect of cloud cover and solar position on the accuracy of ANN models and finds that the presence of solar position as an input can decrease the predicted energy consumption error by as much as 48%.
Review and Evaluation of Using R-C Thermal Modeling of Cooling Load Prediction for HVAC System Control Purpose
Authors: Ogunsola Oluwaseyi T. , Song Li
Published: October 2013

Heating and cooling loads which are compensated by heating, ventilation, and air-conditioning (HVAC) systems, are the main reason for energy uses in buildings. Energy utilized by HVAC system accounts for two-thirds of a building’s total energy consumption. Excessive energy is consumed when HVAC systems fail to operate as intended. This is often due to several factors such as inappropriate monitoring and control strategy, lack of understanding of the dynamics of thermal loads, and system complexity. Amidst several models, estimation of cooling load using Resistance Capacitance (RC) models have proved to provide more robust and accurate estimates of the building load based on measured data but the use of this method is not without challenges. This study aims to highlight common challenges associated with implementation of the RC method for thermal modeling of cooling load. Past and current research have handled some of the challenges by introducing simplifying assumptions which if not adequately selected can lead to significant deviation between model performance and measured data. Without proper understanding of the challenges, engineers may not be able to place a high degree of confidence in load calculation methods and the computer implementations that they use.
Effect of Velocity and Load on the Development of Kinetic Friction at a Lubricated Steel on Polymer Interface
Authors: Bunten Matthew M. , Timpe Shannon J.
Published: October 2013

The effect of normal load and sliding velocity on the development of friction at a lubricated steel pin on polymer disk interface was investigated. Polyoxymethylene homopolymer disks were lubricated with a lithium soap thickened synthetic hydrocarbon grease and tested against a 6 mm diameter stainless steel pin. The normal load was varied from 3 to 80 N, and the sliding velocity was varied from 0.0004 to 0.2 m/s. The engineering friction coefficient displayed a power law dependence on the external applied load, indicating a significant adhesive effect in the presence of the lubricant. The true friction coefficient was 0.04, and the average adhesion force was calculated to be 29 N. With the soft disk and hard pin configuration, velocity and time effects were found to be negligible in the presence of the dominant dependence on the normal load. However, a velocity effect emerged with steel disks and polymer pins, likely due to a temperature rise at the polymer surface.
Heat Transfer Analysis of Internally Grooved Copper Tube R404-A Evaporators
Authors: Onan Cenk , Ozkan Derya B. , Ceran Levent
Published: October 2013

Internally grooved copper tubes are used extensively in HVAC applications, direct expansion batteries and air or water cooled heat exchangers. The advantage of internally grooved copper tubes in evaporator and condenser units is an increase in the refrigerant-side heat transfer coefficient. When an internally grooved tube heat exchanger and a smooth-tube heat exchanger with the same dimensions are compared, the overall heat transfer coefficient and convective heat transfer coefficient are found to increase in different ratios. In addition to this difference, the refrigerant side pressure is found to be a function of the groove geometry, pitch space and choice of refrigerant. In this study, which is different from previous studies in the literature performed using single internally grooved tube condensers and evaporators, refrigerant R404-A is studied in the internally grooved tube evaporator. The heat transfer in the evaporator described here is 30% better than that observed in a conventional smooth-copper-tube evaporator. In the internally grooved tube, the internal surface area is 68% larger than that inside the smooth reference tube. As a result, the convective heat transfer coefficient inside the internally grooved tube is found to be lower than that in the smooth tube.
Effect of Inflow Conditions on the Velocity and Momentum Decay Characteristics of a Submerged Viscoplastic Jet
Authors: Hammad Khaled J.
Published: October 2013

Velocity and momentum decay characteristics of a submerged viscoplastic non-Newtonian jet were studied within the steady laminar flow regime. The governing mass and momentum conservation equations along with the Bingham rheological model were solved numerically using a staggered, variable grid-size, finite-differences scheme. A parametric study was performed to reveal the influence of initial velocity profile, flow inertia, and yield stress presence on the local and global flow field characteristics. Two initial velocity profiles were considered, a top-hat jet, simulating a smooth nozzle contraction, and a fully developed pipe jet. The centerline velocity decay was more rapid for the pipe jet than the top-hat one when the fluid is Newtonian while the opposite trend was observed for yield stress Bingham fluids. The decay in the momentum flux of the pipe jet was always less than that of the top-hat jet. The presence of yield stress significantly reduces momentum and velocity penetration depths of submerged top-hat and pipe jets.
Numerical Analysis of Convection Heat Transfer for Subsea Xmas Tree Assembly
Authors: Ding Kuang , Zhu Hongwu , Zhang Jinya , Luo Xuan , Zhu Junyao , Chang Mu
Published: October 2013

This study aims to investigate the convection heat transfer of a horizontal subsea Xmas tree assembly at a high spatial resolution. Such study is important for increasing the structural reliability design and flow assurance level of subsea Xmas tree. Computational fluid dynamics (steady Reynolds-averaged Navier-Stokes) is adopted to evaluate the forced convective heat transfer of the subsea Xmas tree assembly. The temperature, the convection heat loss and the convective heat transfer coefficient (CHTC) at the surfaces of the subsea Xmas tree assembly are numerically obtained with low-Reynolds number modeling (LRNM). The numerical results show that the outer surface temperatures of the subsea tree are close to that of the ambient cold sea water with the exception of the pipeline. The components along the internal production tubes are typical “hot spots,” which have high CHTHs and cause a great deal of heat loss. Under the designed water depth, the effects of installation orientation and sea water velocity on convective heat transfer are investigated. The overall average CHTCs and the local CHTC distribution of the subsea Xmas tree assembly are depended on the installation orientation. Meanwhile, with the increase of the sea water velocity, the growth rates of the CHTCs for individual components show great difference. Ultimately, for selected installation orientation, the CHTC-sea water velocity correlation is derived by using a power-law CHTC-Uin correlation.
Charge Distribution and Surface Properties of the Tobacco Mosaic Virus 4-nm Central-Pore
Authors: Rodionov Nikolay I. , Maroo Shalabh C.
Published: October 2013

The uniform distribution of charged amino acids along the exterior surface of the tobacco mosaic virus (TMV) along with its unusual structural stability over a large pH and temperature range has made it a model organism for inorganic deposition and nanostructure fabrication studies on biomolecules. However, the potential engineering applications of the virus’s central pore, which is about 300 nm long and 4 nm in diameter, has been overlooked. We aim to expand TMV applications by understanding the surface characteristics of its central pore. We have identified the set of amino acids and atoms that create the surface of the pore, mapped the partial charge distribution of the pore using AMBER9 force fields, and determined the electrostatic potential of the pore surface through Coulomb’s law and Poisson-Boltzmann Equation (PBE). Our analysis has revealed that the pore contains a dense helical distribution of negatively charged glutamic amino acid residues, which results in a strong negative electrostatic potential across the pore. This can potentially be used for water filtration by creating overlapping electric double layer within the central pore.
Multiscale Modeling of Flow and Heat Transfer in Porous Media
Authors: Liu Zhenyu , Wang Huiru , Yao Yuanpeng , Wu Huiying
Published: October 2013

A great number of studies have been carried out to provide the macroscopic descriptions of the overall viscous resistance and heat transfer in the porous media. The new numerical study is necessary to be performed to obtain an understanding of the characteristics at macro/pore scale. The multiscale modeling of the flow and heat transfer in the porous media remains difficult with standard one mesh methods due to the heterogeneity in different scales. In this study, the convection heat transfer is simulated using a macro-scale model including the thermal non-equilibrium assumption. The results, which are validated by the predictions in open literature, show that the convection heat transfer in the porous media can be predicted numerically using a thermal non-equilibrium model. To understand the heat transfer characteristics between the fluid and the solid in porous media, a pore-scale model is developed to obtain the macroscopic properties, especially the convective heat transfer coefficient between two phases. A single cell is simulated to represent a small region in a much larger porous medium. The complex porous structure is reconstructed based on the review of the previous studies and the computational fluid dynamic technique is used to predict flow and heat transfer process. The present work can be extended to study the phase change phenomena in complex structured media, which is normally applied in the latent heat thermal energy storage.
Air-Handling Unit Supply Air Temperature Optimal Economizer Control Experiment
Authors: Thomas Wesley , Song Li , Shim Gyujin , Wang Gang
Published: October 2013

Most air handling units (AHUs) in commercial buildings have an air economizer cycle for free cooling under certain outside air conditions. During the economizer cycle, the outside air and return air dampers are modulated to seek supply air temperature at its setpoint. The supply air temperature is typically set at 13 °C (55 °F) to control humidity in the space. However, dehumidification is not necessary when the outside air is dry. Meanwhile, the space may have less cooling load due to envelope heat loss and/or occupant schedule changes. These facts provide an opportunity to use higher supply air temperature to reduce or eliminate mechanical cooling and terminal box reheat. On the other hand, a higher supply air temperature requires increased air flow as well as fan power. Therefore, an optimization question was formed, through which an optimal supply air temperature is identified to minimize total energy consumption. In our previous studies, through simulation, 90% of energy savings were concluded and a universal control sequence was also proposed for implementing the optimal control strategy. In this paper, experiments were conducted to validate the previously documented theory concerning the optimal supply air temperature reset. The previously recommended universal control sequence is implemented into the building automation system for an air-handling unit control to make the program ready for the next step of verifying energy savings previously simulated. This paper presents optimization control system setup and experimental results showing the program tuning procedures, through which the program is ready for the next step.
Stable Island-Like Water Films Adsorbed on Mica Surface
Authors: Zhao Gutian , Ni Zhonghua , Zhang Yan , Tan Qiyan , Fu Hongyan , Chen Yunfei
Published: October 2013

The nature of water films adsorbed on mica surface in humid environment was studied in this paper. Thickness and water insolubility of the films were investigated by surface force apparatus (SFA) and a stable island-like structure was found when the insoluble part of the films meet La3+ ion. Compared with non-SFA type (e.g. scanning tunneling micro-scope and atomic force microscopy) experiments, SFA has unique advantages in measuring the physical properties of the films. Formation conditions, morphology, composition, water-solubility of the structure were discussed with the help of SFA. It is found that the structure demonstrates different patterns in lower pH values. A prediction model of the structure was proposed to explain these results.
Microfluidic Flow Control and Particle Transport Using Acoustically Actuated Bubbles in Teardrop Shaped Cavities
Authors: Hashmi Ali , Heiman Garrett , Yu Gan , Kwon Hyuck-Jin , Xu Jie
Published: October 2013

It is well known that a symmetric microstreaming flow field will present in the vicinity of an acoustically actuated bubble. In this study, we demonstrate that oscillating microbubbles confined in teardrop-shaped cavities can result in a break in the symmetry of a microstreaming flow field. The teardrop cavity controls the size and shape of the bubble, regulating the volume and therefore its resonance frequency. If actuated in an acoustic field, the induced flow field can then be turned on and off by changing the acoustic actuation frequency. By harnessing the flow field directing capabilities of symmetry breaks and the switching properties of selective excitation of microbubbles, we generate and characterize a microfluidic switch for directing flow direction. We also show that a chain of multiple teardrop-shaped cavities can be used as a transport mechanism for directing particles spatially at high flow speeds. Our results demonstrate that teardrop cavities have great potential in future lab-on-a-chip devices by providing simple solutions to complex flow circuits for temporal and spatial flow control.
A Comparative Study of the Forces Acting on a Human Rider on a Motorcycle for Different Impact Configurations
Authors: Dhinagar Nikhil J.
Published: October 2013

In many parts of the developing countries powered motorcycles are still a primary mode of commutation. Statistics tells us that around 15–20% of the accidents happening across different countries in the world involve motorcycle crashes. With the increased importance placed on the usage of safety helmets or full face helmets by the motorbike riders, head injuries have significantly reduced as compared to the other extremities of the human body. The different segments of the human male model considered for this research are grouped into four main categories, the head and neck, the upper extremities, the lower extremities and the trunk. The center of gravity differs for different segments of the human body as each segment has its own mass. This study aims to form a comprehensive database of the forces acting on the primary human body segments for three accident configurations. The energy content of each of these segments is calculated. The deceleration of the human body after impact of the bike with the obstacle and the distance it travels before reaching zero velocity is also computed. When coupled with the existing knowledge of the injury criteria and biomechanical tolerance limits for the body segments, this can be used in a versatile way to predict injuries that could possibly occur in a bike accident and automate vehicle dynamic controls as a preventive measure. Forces calculated acting on the various human body segments can be used to suitably develop riding protection gear for commercial purposes.
Bending Properties and Finite Element Modeling of Biaxial Weft Knitted Composites
Authors: Demircan O. , Hamada Y. , Kosui T. , Nakai A. , Hamada H.
Published: October 2013

In order to improve the mechanical properties of weft knitted fabric, straight yarns both in weft and warp directions can be integrated. These types of reinforcements are called biaxial weft knitted structures. Finite element analysis is a well known method for analysis of complex construction with complex material properties. Therefore, we wanted to use FEM to express the possibility of prediction of bending properties of complex biaxial weft knitted (BWK) composite structures. The purpose of this study is to investigate bending properties of BWK composites by experimentally and numerically. Two types of six plies composite panels, which include fiber contents, such as glass-glass-aramid and aramid-aramid-aramid, were fabricated by hand lay-up method. After production of composites, bending tests had been conducted on specimens. Glass-glass-aramid composites exhibited superior bending property than aramid-aramid-aramid specimens. The good agreement between the experimental results and numerical results validated the applicability of finite-element method for biaxial weft knitted composites.
Fluid Flow Through Branched Channels in a Fracture Plane in an Enhanced Geothermal System
Authors: Mohais Rosemarie , Xu Chaoshui , Dowd Peter A.
Published: October 2013

Fluid flow in Enhanced Geothermal Systems (EGS) occurs primarily through fractures which are embedded in an almost impermeable granite rock matrix. Experimental and numerical studies have shown that flow in fractures exhibits channeling effects; this means that flow occurs along preferred pathways, most likely the paths of least resistance. There has been evidence to date of dendritic and star-like patterns in granite and as a result, authors have used fractal theory in order to address flow phenomena in these patterns. The application of Bejan’s Constructal theory to this problem however has never been attempted. We base our model on dendritic patterns of flow paths in heterogeneous rock fractures. Flow enters into a main channel which bifurcates into daughter channels of unique dimensions of length and height. We study these parameters for consecutive channels in the flow path and show that for minimization of resistance to flow within a plane using area and volume constraints for a T-shaped channel, a simple relationship holds for the ratios of lengths and heights which will enable maximum flow for this configuration.
The Effects of Asymmetric Micro Ratchets on Dynamic Contact Angle and Pool Boiling Performance
Authors: Brumfield Lance Austin , Park Sunggook
Published: October 2013

The dynamic advancing and receding contact angles of 5μl water droplets were experimentally measured via the droplet impingement technique on a polished brass surface, one brass symmetric micro ratchet, and five brass asymmetric micro ratchet samples of varying dimensions. Droplets were released from varying heights (Weber number) and the impacts studied via high speed camera. Equilibrium advancing and receding contact angles were measured by placing a water droplet on the surfaces and tilting it. Contact angle values were then compared to an existing pool boiling model which incorporates the dynamic receding contact angle, surface roughness ratio, and equilibrium contact angle.
Detection of Concealed Ferrous Objects in Vehicles Using Magnetometry-Based Technology
Authors: Vang Nar , Porumamilla Hemanth
Published: October 2013

Acts of insurgency have become an ever increasing threat resulting in extensive measures being taken by the law enforcement authorities to mitigate their devastating effects on human life and infrastructure. This paper introduces a magnetometry based information, and signal processing methodology for detecting concealed ferrous objects in vehicle body panels. From extensive literature research [6–12], it was observed that while magnetic sensors have been used in a variety of related applications but have not been extensively applied to the on-road detection of firearms and explosives concealed in vehicles. This study utilized an extensive experimental protocol for preliminary concept validation. The main idea behind the approach was that almost all concealed weapons and explosives are made up of a considerable amount of ferrous material and hence produce a local distortion in the magnetic footprint of the Earth’s magnetic field which can then be identified by utilizing sensitive magnetic sensors.

To detect concealed ferrous objects, magnetic signatures of a vehicle door panel were obtained and compared to a base magnetic signature of the same vehicle door panel (the magnetic field data of the same vehicle where no foreign ferrous objects were present), by using a scanning assembly with onboard magnetic and infrared sensors. To analyze the data, a top-down, goal-driven signal processing methodology was designed. To achieve the objective of accurately detecting concealed ferrous objects, simple measures such as magnetic field strength and its energy density were computed, and used in conjunction with more sophisticated statistical measures such as normalized cross-correlation and Mahalanobis distance. Although all these methodologies were able to detect a magnetic footprint anomaly in the presence of a concealed object, the Mahalanobis distance approach in particular provided the most conclusive results in all the cases considered.
Inverse Problem for Lagrangian Dynamics for Multi-Degree-of-Freedom Systems With Linear Damping
Authors: Cho Hancheol , Udwadia Firdaus E.
Published: October 2013

This paper deals with the inverse problem for Lagrangian dynamics for linear multi-degree-of-freedom systems. New results for linearly damped systems are obtained using extensions of results for single-degree-of-freedom systems. First, for a two-degree-of-freedom linear system with linear damping, the conditions for the existence of a Lagrangian are explicitly obtained by solving the Helmholtz conditions. Next, since the Helmholtz conditions are near-impossible to solve for general n-degree-of-freedom systems, a new simple procedure that does not require the use of the Helmholtz conditions and that is easily extended to n-degree-of-freedom linear systems, is developed. The emphasis is on obtaining the Lagrangians for these multi-degree-of-freedom systems in a simple manner, using insights obtained from our understanding of the inverse problem for single- and two-degree-of-freedom systems. Specifically we include systems that commonly arise in linear vibration theory with positive definite mass matrices, and symmetric stiffness and damping matrices. This method yields several new Lagrangians for linear multi-degree-of-freedom systems. Finally, conservation laws for these damped multi-degree-of-freedom systems are found using the Lagrangians obtained.
Bifurcation Analysis of Parametrically Excited Moving String With Aerodynamic Forces
Authors: Qian Changzhao , Chen Changping , Dai Liming
Published: October 2013

Considering the large deformation of the string, A prototypical model of a elastic moving string with aerodynamic forces is studied. The equation of motion is obtained by Newton’s second law. Then the Perturbation method is used to obtain the average equation and bifurcation equation. Based on the average equation, the stable region of this system is discussed. Based on the bifurcation equation, the multivalued property of response amplitude is studied. At last, the flutter effects of aerodynamic force are discussed by the parametric analysis.
The Effect of Multiple Dynamic Absorbers on Regenerative Chatter and Resonance in End Milling Process
Authors: Nakano Yutaka , Takahara Hiroki , Yasue Kengo , Asaga Ryutaro
Published: October 2013

The present study investigates the effect of multiple dynamic absorbers on regenerative chatter and resonance caused by forced vibration generated in the end milling operations. Regenerative chatter is caused by the cutting force variation due to the phase difference between the wave left by the previous cutting edge and the wave left by the current one. This phase difference is expressed as the product of the tooth passing period and chatter frequency [1]. The tooth passing period depends on the spindle rotation frequency and the number of teeth. Chatter frequency is related to the natural frequency of the tool and spindle system. If the integral multiple of the spindle rotation frequency approaches to the natural frequency, the phase difference gets smaller and the critical depth of cut at the onset of chatter is increased. Therefore the critical depth of cut varies with the spindle speed and stable cutting conditions are plotted on the chatter stability lobe, which is a chart that represents the boundary between stable and unstable cuts as a function of the spindle speed and the depth of cut. The chatter stability lobe is widely employed to find the axial depth of cut and the spindle speed in which chatter doesn’t occur. Meanwhile, the cutting force variation by the intermittent cutting with an end milling tool causes the forced vibration. The excitation frequency is determined by the spindle rotation frequency and the number of teeth. When the integral multiple of the excitation frequency approaches to the natural frequency of the tool and spindle system, resonance can be caused by the forced vibration. The resonance occurs in the spindle speed resistant to chatter. Therefore, there is a need for a countermeasure against not just the chatter but also the resonance caused by the forced vibration. In the present study, the cutting conditions which can lead to the chatter and the resonance are investigated by the direct numerical integration method. It is made clear that the optimum tuning parameters of the absorbers to maximize the critical depth of cut vary with the spindle speed. Furthermore, a significant suppression effect on the chatter and the resonance by using the absorbers mounted in a rotating collet holder with a spindle is confirmed.
Effect of Deposition Temperature on I-V Characteristics of Vanadium Oxide Film
Authors: Wei X. Y. , Hu M. , Wang F. , Wei J. , Zhang K. L.
Published: October 2013

In this paper, the effects of deposition temperatures on the resistive switching characteristics of polycrystalline vanadium oxide thin films have been investigated. VOx thin films were prepared by reactive sputtering at various deposition temperatures (RT, 250 °C, 350 °C, and 450 °C, respectively). X-ray photoelectron spectroscopy revealed the compositions of VOx thin films. Electrical switching has been observed in Cu(tip)/VOx/Cu memory units by Semiconductor Device Analyzer. Crystalline characterizations revealed that as-deposited (RT) film was amorphous, the films crystallized into different phases (e.g. VO2, V2O5, VO1.86 etc.) with increasing the deposition temperatures. The VOx memory units have low Vset and Vreset. Furthermore, their set voltage decreased from 1.52 V to 0.45 V and reset voltage decreased from 1.01 V to 0.41 V with increasing the deposition temperatures from 250 °C to 450 °C, respectively. The thin films have three orders of change in resistivity between ON-state and OFF-state except as-deposited film. The vanadium oxide thin film can be a promising material for low power nonvolatile memory applications.
Slip Risk Monitoring in Industrial Workplace Using Mobile Robot
Authors: Loh B. G. , Park D. Y. , Choi G. H.
Published: October 2013

A mobile robot equipped with 3-axis accelerometer, gyroscope, and incremental optical encoders is constructed to evaluate its capability of assessing slip risks in the workplace. The velocity of the mobile robot is controlled by a digital signal processor (DSP) such that the mobile robot is brought to a sudden stop or maneuvers with constant velocity while measuring the accelerations and wheel-rotation speeds of the mobile robot to identify the surface condition of workplace floor. Based on the measurements, a correlation between frictional coefficient and the acceleration and the wheel rotation speed is identified. The mobile robot capable of evaluating the surface condition of a workplace floor is expected to greatly contribute to reducing injuries from slipping and falling in the workplace.
The Application of Image Correlation in Order to Define Chatter During Milling of Titanium
Authors: Koohestani Afshin , Mo John P. T.
Published: October 2013

Self-excited vibration or chatter is the main barrier against milling process. Many techniques have been proposed in order to detect chatter during milling. However, they have some limitations in detection of chatter or using in industry.

This paper addresses if can detect chatter during milling process using image correlation. Image correlation is a method of tracking and image registration for 2D and 3D measurements of changes in images. This method is often used to measure any deformation, displacement, or define any changes during an engineering process.

At this research, Poincaré sections are plotted for milling system by reconstruction of phase space. Then, variation of Poincaré maps is measured and parameterized by image correlation technique using Pearson coefficient.
Using Forming Simulation Results in Virtual Assembly Analysis
Authors: Lindau Björn , Andersson Alf , Lindkvist Lars , Söderberg Rikard
Published: October 2013

In Car Body Assembly Shops, Body in White (BIW), non-rigid sheet metal panels are assembled into car bodies. Depending upon the achieved degree of robustness in part and tool design, the produced items tend to deviate more or less from their nominal specifications. Catching eventual non-robust solutions early on in the development phases is important to minimize time-consuming, expensive testing and trimming activities late in the development- and industrialization phases. To meet these demands, there is today an increased use of virtual forming and assembly tools within the automotive industry. Significant amounts of research have been performed in the area of forming and assembly simulations, but there is still a need to find efficient working methods.

This study has focused upon how forming simulation results can be used in virtual assembly analysis. The predicted springback shapes (offset and variation) of the stamped panels are used in the assembly simulation to study the effects of the part variation when assembled, producing a sub-assembly. The method used is described, and the simulation results are reported. The case shows the potential of using forming simulation results in virtual assembly analysis. Furthermore, the strength of using the Principal Component Analysis technique to describe the part variation in assembly simulations is shown.
The Dynamic Behavior Induced by Different Wind Turbine Gearbox Suspension Methods Assessed by Means of the Flexible Multibody Technique
Authors: Helsen Jan , Vanslambrouck Klaas , Vanhollebeke Frederik , Desmet Wim
Published: October 2013

The continuous demand for increase in power output for new wind parks under strict cost constraints, the greater wind resource at elevation and the desire for fewer machines per Mega-Watt to reduce operations resulted in a demand for bigger turbines. The drive train is an important component in realizing reliable and robust wind turbines. This paper investigates a geared wind turbine. In this type a gearbox is used to convert the low rotor speed to the required high generator speed. In the market several solutions are available to constrain the gearbox in the nacelle. The used configuration significantly determines the gearbox response to rotor loads and the transmission of gearbox vibrations to the turbine. This paper investigates the effectiveness of three configurations: the three point mounting, the double bearing configuration and the hydraulic damper system. The flexible multibody modeling technique can be used to accurately characterize gearbox dynamics. The goal of this work is to use an experimentally validated multibody model of a wind turbine drive train to characterize the ability of the three configurations to minimize the introduction of non-torque loads in the gearbox and the ability to isolate the gearbox vibrations from the rest of the turbine.