bluuebunny/crossref_metadata_2025 huggingface dataset:
Multibody Dynamics Model for Analysis of Human Body Response to Vibrations
Authors: Duan Shanzhong (Shawn) , Mattison Lars , Binkley Teresa
Published: October 2013

Some laboratory studies have showed that vibrational stimulation can enhance muscle strength and improve bone density, but it is not clearly understood how frequency and magnitude of vibration have effects on human muscles and bones. In this paper, a whole-body vibration case study is presented to help understand mechanism of human body responses to vibration intervention. A whole body vibration platform is used to provide a source of vibrational intervention. A person steps up and stands on the platform to experience whole-body vibration. Based on this whole-body vibration intervention case, a multibody biomechanical model is created to represent the human body and the WBV platform, and a sinusoidal force function is used to stand for vibrational input from the platform. Kane’s methods are used to derive equations of motion of this multibody biomechanical system. The model will be used to carry out computer simulation and to analyze how human body response to vibrations.
The Analysis of the Dynamic Behavior of the Nonlinear Oscillations of a Fluttering Plate Based on the Periodicity Ratio Method
Authors: Dai Liming , Wang Xiaojie
Published: October 2013

In this paper, an investigation of the dynamic behavior of a fluttering plate is performed. The governing equations of the nonlinear oscillation derived using Galerkin’s method are presented and solved numerically by the Runge-Kutta method. Four modes are used for accurate results. The periodicity ratio method is briefly introduced and applied to generate the region diagram for the motion of the plate. The corresponding motions under different parameters following the region diagram are illustrated. The results demonstrate the efficiency and accuracy of periodicity ratio method.
Engineering Calculation of Threaded Fastening Systems Considering Deviations in Advanced Design
Authors: Friedrich C. , Hubbertz H.
Published: October 2013

Lighter product design in combination with demand for performance and power capacities of technical products leads to strongly increased stresses of every loaded machine part. This is valid for bolted joints in particular, as these are highly loaded machine elements.

Today threaded fasteners are mostly dimensioned by using standard guidelines based on linear mechanical behavior, like the guideline VDI2230. In product life time non-linear changes and deviations often take place. This has to be considered, if optimized products with high performance, economy, ecology and quality are developed for market needs.

This contribution shows important aspects of bolted joints in life time. A key parameter is the so called ‘preload history’. With this approach the main risks can be accessed directly. In the following paragraphs examples from light weight design — e.g. with CFRP — are demonstrated as well as methods, tools and actions to avoid failures. Conclusions are drawn for methods and tools regarding an effective and economic design process to generate optimized products with bolted joints in the future.
A Parametric Study of Laminar Mixed Convection in a Square Cavity Using Numerical Simulation Techniques
Authors: Hallenbeck K. , Akyuzlu K. M.
Published: October 2013

A parametric study is conducted using numerical experimentation to construct an empirical Nusselt number correlation in terms of Richardson and Prandtl numbers for laminar mixed convection in a square cavity. The square cavity under study is assumed to be filled with a compressible fluid. The bottom of the cavity is insulated and stationary where as the top of the cavity (the lid) is pulled at constant speed. The vertical walls of the cavity are kept at constant but unequal temperatures. A two-dimensional, mathematical model is adopted to predict the momentum and heat transfer inside this rectangular cavity. This physics based mathematical model consists of conservation of mass, momentum (two-dimensional, unsteady Navier-Stokes equations for compressible flows) and energy equations for the enclosed fluid subjected to appropriate boundary and initial conditions. The compressibility of the working fluid is represented by an ideal gas relation. The thermodynamic and transport properties of the working fluid are assumed to be constant. The governing equations are discretized using second order accurate central differencing for spatial derivatives and second order finite differencing (based on Taylor expansion) for the time derivatives. The resulting nonlinear equations are then linearized using Newton’s linearization method. The set of algebraic equations that result from this process are then put into a matrix form and solved using a Coupled Modified Strongly Implicit Procedure (CMSIP) for the unknowns of the problem. Grid independence and time convergence studies were carried to determine the accuracy of the square mesh adopted for the present study. Two benchmark cases (driven cavity and rectangular channel flows) were studied to verify the accuracy of the CMSIP. Numerical experiments were then carried out to simulate the heat transfer characteristics of mixed convection flow for different Richardson numbers in the range of 0.036<Ri<1.00 where the Reynolds number is kept less than 2000 to ensure laminar flow conditions inside the cavity. The velocity vector field maps (circulation patterns) and temperature contours, and temperature profiles along the horizontal axes were generated for different Prandtl numbers ranging from 0.3 to 1. Wall heat fluxes and Nusselt numbers were determined for each parametric study. The collected data from the numerical experiments were then used to construct an empirical Nusselt number correlation in terms of Richardson and Prandtl numbers.
Temperature Distribution in Radial Porous Combustors
Authors: deLemos Marcelo J. S. , Coutinho José E. A.
Published: October 2013

This paper presents two-dimensional numerical simulations of combustion of an air/methane mixture in a radial porous combustor using a model that explicitly considers the intra-pore levels of turbulent kinetic energy. Transport equations are written in their time-and-volume averaged form and a volume-based statistical turbulence model is applied to simulate turbulence generation due to the porous matrix. A cylindrical porous combustor is analyzed, in which the mixture flows inside it in the axial direction, being the flue gases ejected through the lateral surface. Combustion is modeled via a simple closure. For high excess air, the flame front moves towards the lateral exit of the burner. Also, increasing the inlet flow rate for stoichiometric mixture pushes the flame out of the porous material.
Passive Heat Transfer in Porous Enclosures Using a Two-Energy Equation Model
Authors: deLemos Marcelo J. S. , Carvalho Paulo H. S.
Published: October 2013

This paper presents computations for natural convection within a porous cavity filled with a fluid saturated permeable medium. The finite volume method in a generalized coordinate system is applied. The walls are maintained at constant but different temperatures, while the horizontal walls are kept insulated. Governing equations are written in terms of primitive variables and are recast into a general form. Flow and heat transfer characteristics are investigated for two energy models and distinct solid-to-fluid thermal conductivity ratio.
Micro-Cantilever Biochemical Sensing Based on Robust Finite-Horizon Non-Linear Estimation
Authors: Wang Xin , Yaz Edwin E. , Dufour Isabelle , Schneider Susan C.
Published: October 2013

A novel non-linear estimation based micro-cantilever bio-chemical rheological sensing technique is proposed in this paper. Contrary to classical rheological measurements using micro-cantilevers, which is either restricted to resonant phenomena, or based on the measurement of fluid properties over a range of vibration frequencies, the proposed measurement technique can be applied to arbitrary available vibration frequency. By applying non-linear estimation technique, the fluid characteristic parameters including density and viscosity, can be estimated and used to quantify fluid properties. The preliminary simulation studies demonstrate that vibrating micro-cantilevers with nonlinear estimation can be used as effective and robust fluid characterization micro-system in liquid environments. The proposed technique is encouraging for the development of a useful micro-rheometer on a silicon chip for fluid detection application.
Developing Undergraduate Engineering Curriculum Material Using the Heating, Ventilation, and Air Conditioning and Building Management Systems of a High Performance Academic Building
Authors: Baglione Melody , Caubel Julien J.
Published: October 2013

The Mechanical Engineering faculty at the Cooper Union is leveraging a new high performance academic building as a learning resource for students to connect undergraduate theory to professional practice. The new teaching strategy utilizes an energy efficient building to provide students with direct, practical exposure to modern heating, ventilation, and air conditioning (HVAC) and Building Management Systems. Students are taken on tours of the building’s HVAC mechanical rooms and partake in laboratory experiments that illustrate the principles of operation and control of these building systems. Furthermore, the student activities are supplemented with new undergraduate curriculum material that introduces basic thermodynamic principles of HVAC operation and provides an overview of the control systems theory involved. This paper will present the pedagogical motivation and goals of the new teaching methods, an overview of the building systems under study, and the development of corresponding curriculum materials and assessment methods.
Numerical Simulation and Stability Analysis of Thin Flexible Micro Film for Thermotunneling Application
Authors: Enikov Eniko T. , Ganji Mahdi
Published: October 2013

Combined thermionic emission and tunneling of hot electrons (thermo-tunneling) has emerged as a potential new solidstate cooling technology. Practical implementation of thermo-tunneling, however, requires the formation of a nanometer-sized gap spanning macroscopically significant surfaces. Thermo-tunneling is a term used to describe combined emission of hot electrons (thermionic emission) and tunneling of electrons through a narrow potential barrier between two surfaces (field emission). Thermo-tunneling of hot electrons across a few-nanometer gap has application to vacuum electronics, flat panel displays, and holds great potential in thermo-electric cooling and energy generation. Development of new thermo-tunneling applications requires creation of a stable nanometer gap between two surfaces. This presentation is focused on our effort to investigate the stability of the the thin flexible structure under electrostatic and lorenz forces opposing each other. In this presentation, we report the result of numerical simulation with some mathematical simplifications. The mathematical model used for the numerical simulation is well studied in the literature. Using forth-order partial differential beam equation, we studied the steady state solutions of the thermo-tunneling beam model using Galerkin method. Essential output parameters of the model include a central contact area measured by its length (delta) and the thermo-tunneling current. Both parameters are determined as a function of the externally applied external potential and magnetic field. Numerical solutions of the model show two possible operating modes: (1) symmetric deformation with negligibly small current; and (2) asymmetric mode where the B-field controls the current and contact area. Under practical values for the externally applied magnetic and electric fields, it has been shown that the second mode is only possible for electrode with very low work functions, e.g. below 0.5 eV. Therefore, novel materials such as Diamond-like carbon films are likely to be essential in thermo-tunneling applications.
Thermodynamic Analysis of a Reverse Osmosis Desalination System Using Forward Osmosis for Energy Recovery
Authors: Banchik Leonardo D. , Lienhard John H.
Published: October 2013

Thermodynamic analysis is applied to assess the energy efficiency of hybrid desalination cycles that are driven by simultaneous mixed inputs, including heat, electrical work, and chemical energy. A seawater desalination cycle using work and a chemical input stream is analyzed using seawater properties. Two system models, a reversible separator and an irreversible component based model, are developed to find the least work required to operate the system with and without osmotic recovery. The component based model represents a proposed desalination system which uses a reverse osmosis membrane for solute separation, a pressure exchanger for recovering a fraction of the flow work associated with the pressurized discharge brine, and a forward osmosis (FO) module for recovering some of the chemical energy contained within the concentrated discharge brine. The energy attained by the addition of the chemical input stream serves to lower the amount of electrical work required for operation. For this analysis, a wastewater stream of varying solute concentration, ranging from feed to brackish water salinity, is considered as the chemical stream. Unlike other models available in the literature, the FO exchanger is numerically simulated as a mass exchanger of given size which accounts for changing stream concentration, and consequently, stream-wise variations of osmotic pressure throughout the length of the unit. A parametric study is performed on the models by varying input conditions. For the reversible case it is found that significant work reductions can be made through the use of an energy recovery device when the inlet wastewater salinity used is less than the feed salinity of 35 g/kg. For the irreversible case with a typical recovery ratio and feed salinity, significant work reductions were only noted for a wastewater inlet of less than half of the feed salinity due to pump work losses. In the irreversible case, the use of a numerical model to simulate the FO exchanger resulted in a maximum work reduction when the pressure difference between streams was around one half of the osmotic pressure difference as opposed to the precise value of one half found in zero-dimensional exchanger models.
An Analytical Method to Assess Microstructure in Li-Ion Battery Cathodes
Authors: Nelson George J. , Cassenti Brice N. , Peracchio Aldo A. , Chiu Wilson K. S.
Published: October 2013

The successful implementation of electrochemical energy storage and conversion devices within a sustainable energy infrastructure is an inherently multi-scale problem that can benefit from device design at the nano- and micro-scales. These design efforts can be facilitated through the development of analytical models for assessing the merit of microstructural candidate designs. To this end, an analytical model has been developed based on an analogy between charge transport in the presence of electrochemical reactions and thermal fin analysis. This modeling approach provides a method for promptly evaluating microstructures that can be produced with established and novel fabrication techniques. This approach is applied to the assessment of Li-ion battery cathode microstructure by focusing on electronic transport within the solid cathode material. The influence of microstructural morphology on electrode performance is addressed for a set of common cathode materials and the microstructural design implications associated with these materials are discussed.
Vortex Induced Flutter in Compliant Plate Seals
Authors: Trivedi Deepak , Deo Hrishikesh
Published: October 2013

This paper investigates the possibility of vortex induced flutter in GE compliant plate seals (CPS). The CPS consists of a ring of slotted compliant plates attached circumferentially around the rotor, with an intermediate plate seated in the slot. Experiments show that the compliant plates vibrate in the flow field with amplitude that is a function of the differential pressure applied across the seal. The vibrations are caused by potentially multiple flow induced vibration mechanisms operating during different flow regimes. This work focuses on the dynamic instabilities that may be caused by the vortices shed by individual compliant plates and the intermediate plate. We model the compliant plate seal as a ring of a large number of locally coupled oscillators, with nonlinear stiffness arising from hydrostatic feedback. A two-way coupling exists between the structural and wake dynamics, leading to the phenomenon of “lock-in” between the wake and successive modes of seal vibration as the flow velocity is increased. Using eigenvalue analysis, we obtain the transition boundaries that divide the parameter space into sets of regions with positive and negative damping, corresponding to boundaries of onset and end of vortex induced flutter. Based on averaged equations, the amplitude of the limit cycles of the structure and wake dynamics and the phase between them is determined. It is found that the nonlinearities in seal stiffness and the nature of coupling between the compliant plates have a significant effect on the stability boundaries.
A Novel Acceleration/Deceleration Control Algorithm for High Precision Feed Motion System
Authors: Cao Kun , Zhao Wanhua , Liu Hui , Yang Xiaojun , Zhang Jun
Published: October 2013

The feed motion dynamic precision is determined by the properties of the CNC system, the servo control system and the mechanical structure. The Acceleration/Deceleration Control (ADC) in CNC system is widely used to smooth the motion trajectory, so as to reduce transient error caused by vibration. The performance of various ADC algorithms differ significantly, which indicates the importance of developing more effective ADC algorithm. In this paper a novel ADC algorithm called “Asymmetric Double S-shape type Algorithm” is introduced and validated by detailed mathematic deduction, and then its dynamic performance is compared with that of traditional ADC algorithms in both the time domain and frequency domain. The analytical and simulation results demonstrated that, the proposed novel ADC algorithm has notably advantage over the traditional ones in reducing the tracking error in both transient state and steady state, hence is capable of fundamentally improving the feed motion dynamic precision.
A Simplified Model of Laser Hyperthermia of Superficial Tumors Including Variation of Human Tissue Optical Properties With Thermal Damage
Authors: Quist Anne , Timchenko Victoria , Dombrovsky Leonid A.
Published: October 2013

Laser induced hyperthermia is a promising tool in a fight with human cancer especially with superficial deceases such as carcinoma or melanoma. A correct choice of the thermal treatment parameters should be based on modeling of both radiative transfer and transient heating of human tissues. An adequate computational model should allow prediction of the thermal conversions in the cells of the tissues. A computational analysis based on a general approach developed recently by the authors for indirect heating strategy showed that two-dimensional effects of the radiative transfer are not so important for superficial tumors because of a very high extinction of the incident beam. This enabled us to develop a simplified transient model based on 1-D numerical solution for radiative transfer and 2-D axisymmetrical heat transfer model. A difference between the local temperatures of arterial blood and ambient tissue appears to be also not significant for the soft thermal treatment of superficial tumors. The resulting approximate theoretical model based on 1-D solution for radiative transfer and local thermal equilibrium between blood and tissue makes it possible to study a feedback effect of both thermal and optical properties of partially destroyed human tissues on the parameters of the thermal treatment. It is shown that computational error of the simplified approach for typical superficial tumors is negligible. The numerical study for realistic parameters of human tissues showed that the effects of temperature variation of both thermal and optical properties of the tissues are insignificant. The increase in absorption coefficient of the irradiated healthy tissue with degree of thermal damage also did not have a significant effect on a correct choice of the thermal treatment parameters. However, the role of uncertainty in the local thickness and thermal conductivity of the fat layer may be significant and should be taken into account in thermal treatment of superficial tumors.
Thermal Analysis for Designing the Hot-Zone of a Silicon Czochralski Crystal Furnace
Authors: Liu Jun
Published: October 2013

The present work is aimed at developing an axial symmetric thermal analysis model for designing the hot-zone of a silicon crystal growth furnace. An analysis model is developed which can be used to predict the approximate pulling rate and power consumption during silicon crystal growth process when utilizing the Czochralski (CZ) method. In addition, the effectiveness of this analysis model is experimentally confirmed.
Microbubble Array as a Versatile Tool for On-Chip Worm Processing
Authors: Yu Gan , Hashmi Ali , Xu Yuhao , Kwon Hyuck-Jin , Chen Xiaolin , Xu Jie
Published: October 2013

In this study, we present a novel technique for achieving precise trapping, enrichment and manipulation of C. elegans using an array of oscillating microbubbles in a simple microfluidic device. We demonstrate a high trapping efficiency and enrichment of C. elegans characterized by the flow conditions. We also demonstrate for the first time an on-chip manipulation of the pathways of a single C. elegans through temporal actuation of bubbles.
A Numerical Investigation of Impact of Architectural and Climatic Parameters of Windcatcher Systems on Induced Ventilation
Authors: Maneshi Mohammad Mehdi , Rezaei-Bazkiaei Amir , Weber A. Scott , Dargush Gary F.
Published: October 2013

The large energy demand from the HVAC industry for residential buildings, along with the ever growing need for the utilization of renewable sources of energy, has brought considerable attention to the area of induced ventilation. Windcatchers are green architectural structures historically used for the passive ventilation of the indoor spaces with the minimal non-renewable energy consumption. In this paper, a computational fluid dynamics (CFD) model is used to assess a windcatcher’s performance with different characteristics of the windcatcher design. For a single room with heat emitting objects, the effects of the windcatcher louver design and height were thoroughly evaluated in conjunction with a variety of dominant wind velocity and incident angles. A comparison was drawn between the ventilation efficiency for the cases of circular and rectangular windcatcher designs. Thermal discomfort (PD) values due to draft were calculated for different temperature and wind velocities. The developed model was employed to obtain the optimized configuration for the windcatcher-room system. The effect of ambient weather conditions on the results was investigated by performing the simulations for a range of air temperature and velocities. Results obtained in this paper provide windcatcher designers with valuable insights on the important design parameters such as windcatcher height, louver design and impact of ambient conditions.
Brownian Dynamics Simulations of a Dispersion Composed of Two-Types of Charged Spherical Particles: For Development of a New Technology to Improve the Visibility of Rivers and Lakes
Authors: Tamura Satoshi , Satoh Akira
Published: October 2013

In the present study, we treat the dirty (small) and the adsorbing (large) particles as charged and anti-charged spheres and investigate the behavior of these particles under the gravity field by means of Brownian dynamics simulations. We here have discussed mainly the dependence of the adsorption rate on the particle diameter ratio, the volumetric fraction of large particles and the input amount of large particles. The large particles adsorb much more small particles, but the total number of small particles adsorbed by the large particles is larger for large particles with smaller diameter. Hence it is seen that putting a numerous number of adsorbing particles with smaller diameter into water is more effective for removing the suspended substances or dirty particles. Even if the input amount of large particles is increased, an adsorption performance cannot significantly be improved; the number of inefficient large particles that do not contribute to the adsorption performance increases. From these results, we understand that there is an optimal input amount of adsorption agents from a commercial point of view.
A Coupled Transport and Solid Mechanics Formulation for Modeling Oxidation and Decomposition in a Uranium Hydride Bed
Authors: Salloum Maher , Kanouff Mike , Shugard Andrew , Gharagozloo Patricia
Published: October 2013

Modeling of reacting flows in porous media has become particularly important with the increased interest in hydrogen solid-storage beds. It is important for design applications to have an accurate, but relatively simple model for system analysis. We are interested in simulating the reaction of uranium hydride and oxygen gas in a hydrogen storage bed using multiphysics finite element modeling. Our model considers chemical reactions, heat transport, and mass transport within a hydride bed. Previously, the time-varying permeability and porosity were considered uniform. This led to discrepancies between the simulated results and experimental measurements. In this work, we account for the effects of non-uniform changes in permeability and porosity due to phase and thermal expansion. These expansions result in mechanical stresses which lead to bed deformation. To describe this, we develop a simplified solid mechanics model for the local variation of permeability and porosity as a function of the local bed deformation. We find that, by using this solid mechanics model, we improve the agreement between our reacting bed model and the experimental data.
The Flying-Ball-in-Tube Experiment
Authors: Knierim Karl Lukas , Malchow Florian , Sawodny Oliver
Published: October 2013

One of the challenges in teaching applied control theory is to provide students with easy to understand experimental setups, which show complex but comprehensible dynamical behavior. We propose a flying-ball-in-tube experiment with stable, critically stable and unstable behavior. The benefit of the flying-ball-in-tube experiment are its in respect to time scale observable dynamics as well as the simplicity of the setup. A model of the flying-ball-in-tube experiment is derived and analyzed with respect to its stability properties. The derived model is identified and the predicted behavior is validated. In addition, the use of the experimental setup within a one week undergraduate practical is described. Within the course the students program the control environment on a micro controller within the FreeRTOS real time environment and design their own control structure.
Enhanced Mechanical Properties of Poly(Vinyl Alcohol) Nanofibers With Molecular Level Dispersed Graphene
Authors: Qi X. Y. , Ma C. B. , Nai S. M. L. , Cheng C. K. , Zhang H. , Wei J.
Published: October 2013

Graphene oxide (GO) was incorporated to poly(vinyl alcohol) (PVA) to form GO/PVA composite nanofiber membranes with reinforced mechanical properties via electrospinning technology. The effect of exfoliated degree of GO and dispersion sate in the PVA polymer matrix on the morphology and mechanical properties of composites is studied, revealing that the functional side groups of GO can improve the dispersion and interfacial bonding between the GO and PVA matrix. In addition, it also demonstrates the GO/PVA nanofiber membranes with the significant enhanced mechanical properties (2.28-fold increase in tensile stress) are obtained at a low GO loading (0.3 wt%). Our strategy provides new opportunities for the PVA composite to be involved in other potential applications.
Sculpting and Aerosolizing Pinned Liquid Films With Localized Acoustic Pressures of Surface Acoustic Waves
Authors: Taller Daniel , Chang Hsueh-Chia , Go David B.
Published: October 2013

Due to viscous decay, a planar surface acoustic wave (SAW) diffracting from a solid substrate into a liquid film produces a time-averaged, exponentially decaying acoustic pressure in the film. We show that if the film is pinned against a bounding wall, the localized acoustic pressure generates a sequence of surface drops at the contact line, whose dimensions decay in the same exponential manner as the localized acoustic pressure. The undulating interfacial profile near the contact line also inherits this exponential decay, such that the averaged contact angle is exponentially small. The bulk film topology and the aerosolization mechanism are hence insensitive to the wettability of the surface but are controlled only by the localized acoustic pressure and the decaying undulations it produces at the contact line. The size distribution of surface drops is collapsed under the exponential scaling that depends only on the SAW decay rate and amplitude. Numerical modeling based on the Young-Laplace equation is used to model the liquid profile and to predict two aerosolization regimes.
Simulation of Interfacial Corner Cracks in Bimaterial Systems
Authors: Veluri Badrinath , Jensen Henrik Myhre
Published: October 2013

A phenomenological model focused on modeling the shape of such interface cracks and calculating the critical stress for steady-state propagation has been developed. The crack propagation is investigated by estimating the fracture mechanics parameters that include the strain energy release rate, crack front profiles and the three-dimensional mode-mixity along the crack front. A numerical approach is then applied for coupling the far field solutions utilizing the capability of the Finite Element Method to the near field (crack tip) solutions based on the J-integral. The developed two-dimensional numerical approach for the calculation of fracture mechanical properties has been validated with three-dimensional models for varying crack front shapes. In this study, a custom quantitative approach was formulated based on the finite element method with iterative adjustment of the crack front to estimate the critical delamination stress as a function of the fracture criterion and corner angles. The implication of the results on the delamination is discussed in terms of crack front profiles and the critical stresses, which can then be used as the framework for modeling reliability of advanced interconnects system.
Mechanical Property of Glass Mat Composite With Open Hole
Authors: Zhang Zhiyuan , Yang Yuqiu , Hamada Hiroyuki
Published: October 2013

In using process, joints and fasteners always became the weakest area around holes and easy to generate initial damage. At current study, glass chopped fiber mat and unsaturated polyester were used to fabricate glass mat composite (GMC) plates. The influence of open-hole on mechanical property was investigated from tensile test. The decreasing ratio of notched strength from unnotched strength was compared with different size of holes to evaluate the influence of holes size on the sensitivity of GMC. Two sizes of drills, were employed to make drilling hole on the materials. Different damage areas in notched specimens were distinguished. Finally, in order to describe the property of GMC in resistance on open holes, the concept of characteristic distance was introduced. The values were calculated by finite element analysis software (MSC-Marc.) in linear elastic method. Furthermore, the characteristic distance was found that it had a good correspondence with damage characteristics.
A Flat-Panel Ultrasound Robot to Align an Abdominal Ultrasound Probe During Laparoscopic Partial Nephrectomy
Authors: Gumprecht Jan D. J. , Geiger Florian B. , Lueth Tim C. , Stolzenburg Jens-Uwe
Published: October 2013

There were over 28.000 kidney tumor incidences in Germany in 2010. Minimally invasive (laparoscopic) removal of these tumors has become more and more popular. Intraoperative imaging during these procedures is mainly performed with videolaparoscopes. However, they provide only superficial images of the operating field increasing the challenge to remove the tumor. Conventional sonographic approaches may overcome this problem but require an additional assistant to guide the probe. To eliminate the need for an additional assistant, we developed a new robot with four degrees of freedom to motorize a sonographic probe. The robot can be installed in the operating room table and is directly controlled by the surgeon with telemanipulation. In experiments we showed that the accuracy of the kinematic is above the resolution of the sonographic probe.
The Convergence and Algorithm Factors Analysis of Topology Optimization for Crashworthiness Based on Hybrid Cellular Automata
Authors: Guo LianShui , Huang Jun , Zhou Xuan , Tovar Andres
Published: October 2013

Structural design for crashworthiness is a challenging area of research due to large plastic deformations and complex interactions among diverse components of the vehicle. A notable idea in topology optimization is the hybrid cellular automaton (HCA) method capable of topology synthesis for crashworthiness design. The HCA algorithm was inspired by the structural adaptation of bones to their ever changing mechanical environment. This methodology has been shown to be an effective topology synthesis tool.

The objective of this investigation is to examine the convergence and algorithm factors analysis of topology optimization for crashworthiness based on hybrid cellular automata paradigm. The orthogonal test is also proposed to study the effects of the algorithm factors on the dependent variables of the structure with new optimized topology. To demonstrate the convergence properties influenced by factors of the HCA algorithm in dynamic problems, the HCA framework is developed to a methodology for crashworthiness, which combines transient, non-linear finite-element analysis and local control rules acting on cells, and some simple cantilevered beam examples are utilized.
A Study on the Mechanical Stability of a-IGZO Based Inverter
Authors: Kim Byung-Jae , Kim Youn-Jea
Published: October 2013

Amorphous InGaZnO (a-IGZO) thin film transistors (TFTs) are high performance transparent oxide semiconductors (TOS) that are attractive alternatives to poly-Si TFTs, because they provide better uniformity in terms of device characteristics, such as the threshold voltage and mobility. However, the electrical performance of flexible TFTs should have mechanical robustness against substrate bending and stretching without resultant changes. In this regard, many researchers have focused on improving mechanical stability as well as electrical performance of TFTs, such as elasticity and durability under artificial conditions. In this paper, the mechanical characteristics of an a-IGZO based inverters were numerically investigated. The results were graphically depicted when the device was bent by a total of 10% of its length in the x-axis. The mechanical properties of IGZO were assumed to be similar with the zinc oxide (ZnO).
An Experimental Study of Heat Transfer on a Smooth U-Bend Channel Surface
Authors: Wang Lei , Salameh Tareq , Sundén Bengt
Published: October 2013

Experimental studies are carried out to investigate the tip-wall heat transfer in a U-bend channel. Liquid crystal technique is employed to measure the wall temperature and obtain the heat transfer coefficients. The Reynolds number is varied from 10,000 to 24,000. It is found that the tip-wall heat transfer in a U-bend channel is characterized by the feature of jet impingement. The local Nusselt number is scaled by a factor of Re0.5, which is close to the heat transfer scaling in the jet impingement for low nozzle-plate spacings. The result corroborates the previous studies that the jet impingement is a primary mechanism to enhance the heat transfer in a U-bend channel.
Study of Natural Ventilation Flow in a Room Fitted With a Solar Chimney
Authors: Goriel K. , Avakian V. , Huynh B. P.
Published: October 2013

The past few decades have seen a considerable change in terms of technological innovation. The recent technological trend is a shift towards the incorporation of natural processes such as hydro, solar and wind in design and implementation. For the purpose of this report, a miniaturised solar chimney test rig was constructed which utilises the principles of natural ventilation. Analysis of similar types of technologies was conducted and various ideas considered in the construction of the test rig. Computational fluid dynamics software was also used in conjunction with the experiment to see the similarities associated with the experiment and software package, taking into account the limitation of various instruments. A comprehensive experimental and theoretical approach was developed and reported.
A Strategy for Estimating State-of-Charge and State-of-Health of Li-Ion Batteries in Electric and Hybrid Electric Vehicles
Authors: Zhao Xiaowei , Zhang Guoyu , Yang Lin
Published: October 2013

A task that has to be solved for the application of batteries in vehicles with an electric drive train is the determination of the actual state-of-health (SOH) and state-of-charge (SOC) of the battery cells. In this paper, an on board strategy for estimating SOC and SOH of Li-ion batteries is proposed. The equivalent circuit model is used for both SOC and SOH estimations. In SOH algorithm, the estimated value of battery capacity not only reflects the aging degree of battery pack, but also provides information for SOC estimation. Meanwhile, the extended Kaiman filtering is used in SOC estimation. Because the performance of the equivalent circuit model will be better at small currents than at high currents, extended Kaiman filtering is substituted by Ampere-Hour counting when the absolute value of current is greater than a calibration value. The Digatron battery tester was used to evaluate the proposed estimation method, and results show that the estimation method has high accuracy and efficiency at ordinary temperatures.
Development of Cutting Support System by Bilateral Control With Variable Connecting Force Between Master and Slave Robot
Authors: Osada Tsuginobu , Kato Norihiko , Yano Ken’ichi , Fofana Mustapha S.
Published: October 2013

Finishing processes such as deburring are performed on a wide variety of products in various quantities by workers on a piece-by-piece basis. Accordingly, the accuracy of the product depends on the worker’s skill. To solve this problem, the bilateral control system is applied to a machining support system. The aim of this research is to develop a machining support system via the bilateral control system which can accept various machining theories and to reflect the operation force into the machining geometry. This system has a construction which makes it possible to change the connecting force between a master and a slave robot based on a symmetrical bilateral controller. This construction is useful to change the feature of a system dynamically according to machining condition. The effect of this system is shown by the experiment results.
CFD Analysis and Optimization of a Variable Shape Airship
Authors: Dumas Antonio , Trancossi Michele , Madonia Mauro , Pascoa Josè , Ilieva Galina , Coppola Agostino
Published: October 2013

This paper presents the CFD simulation of a novel airship concept that can change the external volume and shape as a function of altitude. This novel concept of airship defined in the MAAT project (the project of a stratospheric cruiser/feeder airship) is necessary for two fundamental reasons: minimizing risks due to the use of hydrogen as buoyant gas and reducing the power necessity for propulsion. The unconventional feeder system has been analyzed from ground level up to 16,000 m, which the desired operative altitude of the cruiser.
Numerical Study on Evolution of Sessile Water Droplets During Evaporation
Authors: Hu Dinghua , Wu Huiying , Wu Xinyu
Published: October 2013

The evaporation of sessile water droplets has been investigated numerically in this paper. A numerical model based on the quasi-stationary assumptions is established for describing the evaporation dynamics. Droplets are assumed to be pinned and axisymmetric on a substrate during the evaporation, and the influence of Marangoni effect on the evaporation has been taken into account. In a self-consistent way, the vapor concentration field in the gas phase, the velocity field in the liquid phase, and the temperature field in both liquid and gas phases have been calculated using the finite element method (FEM). A novel iteration algorithm is proposed to study the time evolution of contact angle. From the numerical results, we derived a universal correlation of the contact angle with the dimensionless time. The correlation, which is validated against experimental data from open literature, is independent on the contact radius, substrate temperature and ambient humidity. Base on this correlation, a simple expression has been further developed to estimate the evaporation time, and the predictions are in good agreement with the experimental results from open literature. The work in this paper provides an extensive understanding of the evaporation of sessile droplets.
Lattice Boltzmann Simulation of Thermal Multiphase Flows With Dynamic Wall Interactions
Authors: Ikeda Michael K. , Schaefer Laura A.
Published: October 2013

As energy densities in electronic devices rapidly increase, improved two-phase microchannel heat exchanger designs are of great interest. However, a better understanding of flow boiling in these regimes is required. The lattice Boltzmann method (LBM) has shown great promise in the simulation of multiphase flows due to its ability to easily capture interfacial dynamics. This is in contrast to the complicated interface-tracking algorithms required when applying traditional computational fluid dynamics approaches to multiphase flow problems. However, while there have been many recent development to the standard thermal, multiphase LBM, wall interactions are typically oversimplified. These simplifications lead to interactions which are only appropriate for isothermal, static simulations. In this work, we extend the wall interaction potential based on the pseudopotential multiphase approach to correctly model the variable wetting behavior that occurs with changing temperatures. This will enable the future modeling of the flow boiling process with thermally-influenced wetting characteristics.
Flying Octopus — A LTAV With Wire-Driven Flapping Wings
Authors: Li Zheng , Du Ruxu , Yao Yupei
Published: October 2013

Traditional lighter-than-air-vehicles (LTAV), i.e., airships, are propelled by propellers. In this paper, an indoor LTAV “flying octopus” with four flapping wings is designed and built. The flying octopus has three parts: the balloon, midsection, and the wings. The balloon is filled with helium. Its buoyance is used to balance the major part of the flying octopus’s gravity. The midsection connects the balloon and the wings, and also holds the actuators, control board and power system. Four flapping wings are identical and each wing is composed of a continuous backbone, a membrane, a pair of wires and a number of eyelets. The flapping motion is achieved by the novel wire-driven mechanism. A prototype with a total mass of 1592g is built. The motion of the flying octopus is controlled by the four wings. Indoor experiment results show that, with the four flapping wings, the flying octopus can go in all directions, i.e., forward, backward, leftward, rightward, upward, and downward effectively.
Optimal Layout of an Offshore Crane Using Topology Optimization
Authors: Jang In Gwun , Kwak Byung Man
Published: October 2013

Mobile Harbor (MH) recently proposed by KAIST is a novel maritime cargo transfer system that can go out to a container ship anchored in the deep sea and handle containers directly at sea with the aid of the MH crane. Since this system operates under the open sea condition, the MH crane should be newly designed to support inertia load and wind force as well as its self-weight. Wave-induced motions of MH such as rolling, pitching, and heaving generates a significant amount of inertia load, which is ignored in the design of conventional cargo cranes installed on the stable ground. Wind force is also critical to consider a higher level of wind velocity in the open sea. In addition to structural rigidity, mass minimization is important in the design because it generally reduces overturning moment and therefore enhances ship stability. In this paper, we applied topology optimization to the stage of conceptual design for the MH crane, considering all the aforementioned features. We systematically obtained a design candidate through computational framework.
Continuous Particle Size Distributions in a Bubbling Fluidized Bed Using Discrete Element Method
Authors: de Souza Braun Meire Pereira , Caserta Alice Jordam , Navarro Helio Aparecido
Published: October 2013

The focus of this paper is to study the behavior of systems with continuous particle size distributions over a gas-solid flow in a bubbling fluidized bed. A lognormal distribution with particle-size range between 800 micrometers and 900 micrometers was used to perform numerical simulations to investigate gas bubbles formation for a polydispersed system. Different drag models were used to predict the bubbles. Species segregation for a binary mixture and a monodispersed system were also studied. Discrete Element Method (DEM) simulations were performed using the source code MFIX (“Multiphase Flow with Interphase eXchanges”) [1] developed at NETL (“National Energy Technology Laboratory”). The bubble size of a single injected bubble depended strongly on gas-particle drag model used. The influence of the gas bubbles in the mixture and segregation was analyzed and discussed. The results were compared with experimental results from the literature and a good agreement were obtained.