bluuebunny/crossref_metadata_2025 huggingface dataset:
Friction-Induced Squeak of Ceramic-on-Ceramic Hip Implants: A Stability Design Criteria
Authors: Sidebottom Mark , Paliwal Manish
Published: October 2013

Friction-induced squeaking has been reported in 1–10% of patients who have a ceramic on ceramic total hip replacement, which is a subject of annoyance. The goal of this study was to investigate the possible factors attributing to the hip squeak, and understand the underlying phenomenon. The investigation involved acoustic, modal, and mathematical analyses. Acoustic analysis involved extracting and analyzing audio data from the videos files of squeaking ceramic hips. The audio data was transformed from the time to frequency domain using Fast Frequency Transform (FFT) using MATLAB. This allowed the identification of the squeal frequencies. Modeling involved 3-D rendering of the hip implant (femoral stem, head, cup liner, and the cup shell) using computer-aided-design software. Mathematical analysis involved the investigation of the role of the frictional stick-slip phenomenon of the metal shell and ceramic liner on squeal using a 2-DOF mathematical model. Mass, stiffness properties, and coefficient of friction of the components were incorporated to study the limit cycle using MATLAB/Simulink, which is an indicator of the stability of the system. Modal (Numerical) analysis involved the evaluation of the modal frequencies of the components using ANSYS, to investigate their contribution to squeal. Acoustic analysis of the squeal frequencies showed that the range of squeal frequencies of the coupled system ranged from 1500–3000 Hz, which concurred well with the literature. Modal Analysis showed the metallic shell’s resonant frequency at 4600 Hz. The parametric analyses using the 2-dof model showed that a stable system was approached as the stiffness of the liner was increased. The increase in mass of the shell resulted in larger limit-cycles. Increased stiffness of the shell proved to stabilize the system for most loading conditions.
An Optimum Method of Capturing Interface and a Threshold Weber Number for Inclusion of Surface Tension Force in Simulation of Nozzle Internal Flow in Pressure Swirl Atomizers
Authors: Abbasi Baharanchi Ahmadreza , Nordin Darus Amer , Ansari Manizheh , Abbasi Baharanchi Ehsan
Published: October 2013

Numerical study of internal nozzle flow in simplex atomizer is now well established to represent features of the flow such as turbulence, swirl, and interface between phases. However, an attempt is still needed to introduce an optimum method to capture the interface between liquid and gas with satisfactory level of sharpness. Besides, a detailed study must be dedicated to quantify the influence of surface tension force on evolution of interface shape and flow variables and to determine the necessity of inclusion of this force in molding of this particular type of flow. In the present study RNG K-ε model has been used in Fluent 6.3 to compare performance of four interface schemes and introduce an optimum method in terms of computational effort and grid size requirement. Later, combination of the CSF model, RNG K-ε model and Implicit scheme has been used to introduce a threshold Weber number below which inclusion of surface tension will considerably influence the flow field during intermediate time steps.
Unusual Fast Evaporation From Nanoholes
Authors: Huang Zhi , Hu Yuanchen , Liu Kang , Hu Xuejiao
Published: October 2013

Water evaporation is an important physical phenomenon that occurs in nature and several industrial applications such as food drying processes, cooling in air-conditioning systems and desalination. In all these systems, it is necessary to have a good prediction and control of evaporation rate as a function of various system parameters. Attempts to understand the affecting factors have mostly focus on the flow rates of gas or water streams, relative humidity of the air, presence of dissolved or suspended material in the water, temperatures of the air and water streams. However, as water surface partially covered (less surface area) is generally thought to have lower evaporation rate, little notice has ever put on it.

Here we consider the evaporation case of water surface covered with nano-through-hole lid (NHL) of which the radius size is nearly equal to the average free path of the vapor. Using a gravimetric method, we experimentally measured the evaporation rate of water at the orifice of the nano-holes. The results indicate that the evaporation rate is 1–6 times faster than the non-sheltered water surface with the same liquid area. Moreover, with the porosity of the lid decreasing, the evaporation rate per unit area increases. A theoretical model is developed for this novel phenomenon from the view of molecular dynamics during evaporation and vapor diffusion. We envision that this finding may have new inspirations on phase change phenomenon in nano-confined space and put forward one new way for promoting evaporation of liquid.
Value of Reservoir Storage for Resilient Power Plant Cooling and Basin-Wide Water Availability
Authors: Stillwell Ashlynn S. , Webber Michael E.
Published: October 2013

Since many thermoelectric power plants use water for cooling, the power sector is vulnerable to droughts, heat waves, and other water constraints. At the same time, large water demands for power generation can strain water availability for other users in a river basin. Opportunities exist for power plants to decrease freshwater demands, increasing both drought resiliency of power plants and water availability for other users in the basin. One particular method of decreasing freshwater demands for power plants is by incorporating reservoir storage into cooling operations. Using reservoir storage allows water to be recirculated and reused for power plant cooling, thereby decreasing water withdrawal requirements. Water storage also has the added benefit of making water available during times of shortage.

While storage is known to be beneficial, no tools exist to explicitly quantify the basin-wide water availability impacts and increased power generation resiliency possible via constructing water storage at thermoelectric power plants without existing reservoirs. Here we present the results of modeling efforts regarding the value (both in terms of resiliency and water availability) of reservoir storage for power plant cooling and basin-wide water availability in the Brazos and Colorado River basins, using a customized river basin based-model along with existing Texas Water Availability Models. Results vary between river basins and different water availability models, with construction of new reservoirs generally increasing basin-wide water availability in the Brazos River basin and generally decreasing basin-wide water availability in the Colorado River basin. We conclude that the value of reservoir storage for power plant resiliency and basin-wide water availability is highly site-specific.
Modeling and Impact Analysis of Football Helmets: Toward Mitigating mTBI
Authors: Honarmandi Peyman , Sadegh Ali M.
Published: October 2013

Head injuries, especially concussions, have become a subject of deep concern particularly in contact sports such as American Football. There is always a need to improve the design of football helmets in order to lower the risk of concussion. In this research, we developed a mathematical model to physically describe the head and helmet together against an impact load. The mechanical properties of helmet materials were obtained through compression tests and hysteresis loop experiments. These experimental data along with biomechanical data of head and brain available in literature were incorporated into our modeling and analysis. A code was developed to conduct impact analysis and the results are illustrated and discussed accordingly.
Investigation of Lower Thermal Conductivity Ni-Cu Wicks for Loop Heat Pipes
Authors: Xin Gongming , Cheng Lin
Published: October 2013

In this study, a series of sintered nickel-copper wicks with different ratios of copper powders in the mixture of wicks were fabricated, with the effective thermal conductivities (ETC) experimentally investigated by using the steady-state method. The ETC of wick with composition of 60% nickel and 40% copper presents the lowest value among the tested range. Comparisons of some existing models for predication of porous effective thermal conductivity to experiment results were performed, but no reasonable accurate predictions were found for the tested Ni-Cu wicks.
Actuation Technologies Suitable for Humanoid Robots
Authors: Tadesse Yonas
Published: October 2013

Actuator selection is a key component in the design and development of humanoid robots. The issue of actuation technologies is a fundamental question that determines the level of complexity and ability of the machine to perform similar functions to that of a human, and needs continuous assessment at all level of design and technological advancement. The main objective of developing humanoid robots is to mimic the behavior of human to that of the machine and the prototypes presented so far can be categorized as machine-like and human-like robot. The former is focused on mobility, and the later one on the behavior of the robot including gesture synthesis, facial expression illustrating the internal emotion of the robot and generally on the cognitive aspects. Humanoid Robots with Facial Expressions (HRwFE) are getting momentum and there exist a strong derive to build them because they can potentially be used for various applications including health care, military, industry, and household. For all kinds of humanoid robots, the selection of actuators is challenging. It is not only the stress, strain, energy density, power consumption, life cycle, linearity, repeatability, response time, band width and etc. But other factors such as ease of control, availability, maturity, and cost of the actuation technology have significant importance. This paper focuses on the issues mentioned above and presents comparative assessment of the actuation technologies for humanoid robots focusing on humanoid head.
The Effects of Ions and Surface Charge Density on Water Distribution in Silicon Nanochannel
Authors: Qiu Yinghua , Tan Qiyan , Guo Weichuan , Chen Yunfei
Published: October 2013

Water distributions are obtained in the silicon nanochannels filled with NaCl solution and pure water with molecular dynamics simulation, respectively. Taking into account the reality at the solid-liquid interface, the silicon atoms of channel walls in the model are allowed to vibrate at their own equilibrium positions. Results show that: The water distribution vertical to the channel wall changes notably due to the introduction of Na+ ions and Cl− ions. In pure water case, there are three water aggregation peaks within 0.4nm from surface, in contrast to two in NaCl solution case. Also, the locations and values of the corresponding peaks alter except the first one. However, the water distribution for NaCl solution beyond 0.5nm shares the same trend with that in pure water and the water molecules alignments in the first layer have almost the same trend in the two cases. Furthermore, in pure water system, the influence range of surface charge is 0.55nm and with surface charge density increasing, the first concentration peak changes into three ones within 0.4nm perpendicular to the surface and the water molecules in the first water layer align more orderly.
A Study on the Internal Thermal Problems for Low Temperature Furnace in Semiconductor Processing
Authors: Joo Kang-Woo , Jeong Duwon , Suh Mason , Kim Kwang-Sun
Published: October 2013

The low temperature furnace for semiconductor processing is applicable not only to the equipment which needs heat treatment on the silicon wafer but also to the industry field similar to semiconductor manufacturing. The target process in this research is for the low temperature furnace less than 500°C. The investigation on controlling the flat zone at low temperature range has been important with the recent development trend of miniaturized device and new materials. When the temperature in the furnace is changing, the temperature changing rate is slower at the batch type than the single type. The thermal problems therefore occur including the unnecessary heat treatment and the thermal shock of wafer for the sudden heat change. The research target is therefore to obtain the uniform temperature distribution in a whole furnace when manufacturing the low temperature heat treatment equipment. The precise control of the temperature of the reactor is a crucial factor obtaining the vapor deposition uniformity on the wafer surface. In this research, we validate the reliability of numerical analysis by being compared with the experimental results. And the different parameters that affect the internal temperature distribution including the radiant heat transfer are investigated using CFD for designing and manufacturing the furnace. To obtain the uniform temperature distribution of the reactor, the emissivity and reflectivity of pedestals which are installed under the wafer cartridge are also changed and investigated along with the different number of pedestals and distance of pedestals from the bottom of the wafer cartridge. As the results, the most effective design factor is the temperature of each heater to make the wafer temperature uniform. Additionally, the yield rate per one process is increased when the number of wafers is increased because the flat zone is widened.
Spatial Actuation Effectiveness of Segmented Actuators on Parabolic Cylindrical Panels
Authors: Hu S. D. , Li H. , Tzou H. S.
Published: October 2013

With the distinct capability of line-focusing, open parabolic cylindrical panels are commonly used as key components of radar antennas, space reflectors, solar collectors, etc. These structures suffer unexpected vibrations from the fluctuation of base structure, non-uniform heating and air flow. The unwanted vibration will reduce the surface reflecting precision and even result in structure damages. To explore active vibration and shape control of parabolic cylindrical panels, this study focuses on actuation effectiveness induced by segmented piezoelectric patches laminated on a flexible parabolic cylindrical panel. The mathematical model of a parabolic cylindrical panel laminated with distributed actuators is formulated. The segmentation technique is developed and applied to parabolic cylindrical panels, and the piezoelectric layer is segmented uniformly in the meridional direction. The distributed actuator patches induced modal control forces are evaluated. As the area of actuator patch varies in the meridional direction, modal control force divided by actuator area, i.e., actuation effectiveness, is investigated. Spatial actuation effectiveness, including its membrane and bending components are evaluated with respect to design parameters: actuator size and position, shell curvature, shell thickness and vibration mode in case studies. The actuation component induced by the membrane force in the meridional direction mainly contributes to the total actuation effectiveness for lower modes. Average and cancellation effect of various actuator sizes and the optimal actuator position are also discussed. Results suggest that for odd vibration modes, the maximal actuation effectiveness locates at the ridge of the panel; while for even modes, the peak/valley closest to the ridge is the optimal position to obtain the maximal actuation effectiveness. A segmentation scheme of the meridian interval angle 0.0464rad for the investigated standard panel is a preferred tradeoff between the actuation effectiveness and practical feasibility. The modal actuation effectiveness increases with the shell curvature, whereas decreases when the shell thickens.
Simulation of Hydrogen Diffusion and Adsorption on Single-Walled Carbon Nanotube
Authors: Liu Y. H. , Tian B. , Wang F. , Wei J. , Zhang K. L.
Published: October 2013

With clean fuels increasingly used for transportation due to environmental concerns and limited supply of fossil fuels, hydrogen is attracting more attention as a clean fuel free from carbon dioxide and other greenhouse gas emissions. Analysis of hydrogen diffusion in single-walled carbon nanotube was performed with molecular dynamic simulation. The carbon nanotube is chosen because of a well-known fact that it is an excellent adsorption material with high surface volume ratio. In this paper, diffusivity rate are simulated to study the interaction of molecular and atomic hydrogen with single-walled carbon nanotubes. The adsorption energy and repulsive energy are analyzed to explore the nanotube structure after desorption and the mechanism of desorption. Electric charge density is also studied in order to understand better the process of hydrogen adsorption in CNT. A background of the hydrogen storage problem with carbon nanotubes is provided and the issues to be resolved have been highlighted. Future directions to address these challenges have also been suggested. We make a case that molecular simulation studies can identify the most promising structures and compositions to maximize hydrogen storage.
Micro-Scale Thermal Sensor Manufacturing for Semiconductor Furnace Chamber
Authors: Yang Hongcheon , Kim Jun Young , Kim Kwang-Sun
Published: October 2013

As the demand of complex and small scale semiconductor devices has been increased, the measurement technologies were developed to meet the accurate requirement in semiconductor manufacturing process. The uniform temperature requirement on the wafer is the major factor related to the semiconductor device yield. It is normally acquired from the thermocouples following the inner wall of the chamber. However, since the temperature difference between the wall of equipment and the surface of wafer is existed, the actual wafer temperature is commonly measured by a thermocouple wafer to calibrate the temperature measurement accuracy of the equipment. However, as the diameter of the commercial thermocouple wires is larger than the recently demanded pattern size, the TC wafer has not been able to measure the micro scale temperature differences on the micro patterned wafer. We, therefore, designed a micro-scale thermal sensor. The developed sensor has 37 sets of the measurement points on a 4-inch silicon wafer. The size of the measurement point is approximate to 16 um2. Two alloys, chromel and alumel which are as same as the materials of the K-type thermocouple are used to generate the thermoelectric voltage. The sensor has the temperature range of −200°C to 1300°C. The commercial K-type thermocouple extension wires are connected to the pads of the sensor array and they transfer the analog voltage data to a data acquisition device (DAQ). The sensor was calibrated by comparing the EMF voltage at different temperatures to the standard thermocouple EMF voltage. With the developed micro-scale thermal sensor system, the temperature distribution of the wafer in the furnace chamber is obtained.
Optical Properties of Nano-Structure Tungsten-Doped Vanadium Oxide
Authors: Cai W. B. , Wang F. , Miao Y. P. , Wei J. , Zhang K. L.
Published: October 2013

Tungsten-doped vanadium oxide has been proved to decrease the transition temperature, which enables vanadium oxide film to be more promising. Besides, the nano-structure can improve the properties of the film when compared with the as-deposited film. In this letter, a nano-structure tungsten-doped vanadium oxide film is proposed. Tungsten-doped vanadium oxide film was deposited on the Si (400) substrate by DC magnetron sputtering. The doping level was controlled by adjusting the sputtering time. Then the as-deposited film was annealed to form a nano-structure film at the temperature of 500 °C for 1 h in high vacuum. The morphology and crystalline structure of such films were characterized by AFM and XRD, respectively. Optical properties of the films were tested by FTIR, mainly comparing the infrared transmission before and after annealing.
A Study on Cooling Methods to Decrease the Internal Temperature of the Chip Mounter
Authors: Kim Dae-hyeon , Lee Young-nam , Kim Kwang-Sun , Kyeong Hyeon-tae
Published: October 2013

As a chip mounter demands the high speed and accuracy, the exact reviews of thermal deformations are necessary in these equipments although those are a relatively small. These deformations have a bad influence on the specification of the product or its productivity because the products are manufactured with a micro scale accuracy. The linear motor in chip mounter has an advantage that more comfortably control the linear motion of the motor than the rotary or ball-screw type one. But the linear motor has a disadvantage about thermal problem than the other types. The heat has an effect on the life of the motor and its performance. It causes the mechanical errors by thermal stress and deformation. The heat transfer analysis is complex in chip mounter because of a plate being contacted with the moving linear motor coil on the fixed frame with which the magnetic is attached. For this reason, the trial & error methods have been used for most cases. In this research, we analyzed the thermal stress and deformation of the plate being contacted with the linear motor coil and thermal problems in the equipment using CFD. The reliability of the numerical analysis is verified by being compared with the experimental results. The suggested model is investigated with installing the fans on the upper cover, which confirmed decreased the temperature on the important parts of the equipment.
Precision Gravure Printing of Conductive Ink on Flexible Substrate for Printed Electronics
Authors: Yoon Deokkyun , Lee Seung-Hyun
Published: October 2013

In attempt to lower the production cost, roll-to-roll printing is gaining attention in electronics industries. Gravure printing, which has been the method of choice in the graphics industry for years thanks to its high resolution and process speed, is utilized to print conductive lines on flexible substrate. The main benefactors of such utilization are touch screen panel, RFID tags, thin film photovoltaics, and printed circuit board industries. The preferred substrate for conductive line printing is polymer. Due to its highly flexible nature, the printed electronics is highly flexible and is expected to create new markets where the rigid silicon and glass based electronics could not. In this work, the effect of gravure cell and trench on printing thin conductive lines as low as 20 μm line width on the polyethylene terephthalate (PET) substrate is presented. Various printing orientations including the machine direction, the cross direction, and the 45° grid mesh are used and the respective orientation’s printability is discussed.
Finite Element Analysis of Functionally Graded Thick-Cylinders Subjected to Mechanical and Thermal Loads
Authors: Ahmed Jasem A. , Wahab M. A.
Published: October 2013

Functionally graded materials (FGM) are used to design structures used in high temperature environment. Hybrid pressure vessels can be designed from FGMs to incorporate improved strength, weight reduction, thermal properties, impact resistance etc. Progressive research in this area will lead to the determination of optimum design parameters and provide insight in developing manufacturing techniques of full-scale hybrid pressure vessels and experimental validation. In future, an accurate damage model will help in planning component examinations in a selective manner in order to provide useful information about material condition and predict the remaining life of the structure.

A functionally graded thick-walled cylindrical vessel with varying material properties in the radial direction is considered. The cylinder is assumed to be made of one phase spatially dispersed in a matrix of another. Volume fractions of the phases are assumed to vary along the radial direction according to power laws. The gradation is represented by dividing the radial domain into finite sub-domains. The effective material properties such as modulus of elasticity, Poisson’s ratio, thermal conductivity and coefficient of thermal expansion are estimated using Mori-Tanaka [1], Hashin–Shtrikman [2], Hatta-Taya [3] and Rosen-Hashin [4] relations. The hollow cylinder is subjected to axisymmetric mechanical and thermal loadings. Finite Element Analysis is performed using a commercial package, ANSYS, to obtain temperature and stress component distribution along the thickness of the cylinder. Results are presented graphically to show the effect of internal pressure, temperature change, and gradient variation of material properties on stress components throughout the thickness.
Periodic Forced Convection in a Darcy Metallic Foam: The LTNE Model
Authors: Rossi di Schio Eugenia , Barletta Antonio
Published: October 2013

The present paper studies the thermal entrance region in a concentric annular duct filled by a fluid saturated porous metallic foam, with reference to steady forced convection and to a thermal boundary condition given by a wall temperature longitudinally varying with a sinusoidal law. The effect of viscous dissipation in the fluid is taken into account, and a two-temperature model is employed in order to evaluate separately the local fluid and solid matrix temperatures. The governing equations in the thermal entrance region are solved numerically by the method of lines. The Nusselt numer and its mean value in an axial period is evaluated, with reference both to the inner and the outer boundary.
Exergetic Assessment of a Syngas-Redox (SGR)-Based IGCC Plant for Generating Electricity
Authors: Sorgenfrei M. , Tsatsaronis G.
Published: October 2013

Carbon capture from advanced Integrated Gasification Combined-Cycle (IGCC) processes should outperform conventional coal combustion with subsequent CO2 separation in terms of efficiency and CO2 capture rates. This paper provides a thermodynamic assessment, using exergy analysis, of a novel Syngas Redox (SGR) process for generating electricity. The power island of the proposed process uses syngas produced by coal gasification and then cleaned through high-temperature gas desulfurization (HGD). Hematite (Fe2O3) is used as an oxygen carrier to oxidize the syngas. To achieve a closed-cycle operation, the reduced iron particles are first partially re-oxidized with steam and then fully re-oxidized with pressurized air.

One advantage of this design is that the resulting hydrogen (using steam in the re-oxidation section) can be utilized within the same plant or be on sold as a secondary product. In the proposed process, diluted hydrogen is combusted in a gas turbine. Heat integration is central to the design. The different requirements of syngas cooling, particle-regeneration, and coal drying necessitated the use of a heat-recovery steam generator (HRSG) supplying steam at three pressure levels.

To establish a benchmark, the rate of exergy destruction within the SGR process was compared to a coal-fed Shell gasification IGCC design with Selexol-based pre-combustion capture. Process simulation was undertaken using Aspen Plus and EES (Engineering Equation Solver).
An Example of Thermo-Economic Optimization of a CCGT by Means of the Proper Orthogonal Decomposition Method
Authors: Melli Roberto , Sciubba Enrico , Toro Claudia , Zoli-Porroni Alessandro
Published: October 2013

This paper presents an application of the Proper Orthogonal Decomposition (POD) technique (also called Karhunen-Loève Decomposition, Principal Component Analysis, or Singular Value Decomposition) to the thermo-economic optimization of a realistic Combined-Cycle Gas Turbine (CCGT) process. The novel inverse-design approach proposed here employs the thermo-economic cost of the two products as objective function.

The proposed procedure does not require the generation of a complete simulated set of results at each iteration step of the optimization, because POD constructs a very accurate approximation to the function described by a certain number of initial simulations, and thus “new” points in design space can be extrapolated without recurring to repeated process simulations. Thus, the often taxing computational effort needed to iteratively generate numerical process simulations of incrementally different configurations is substantially reduced by replacing much of it by easy-to-perform matrix operations: a non-negligible but quite small number N of initial process simulations is used to calculate the basis of the POD interpolation and to validate (i.e., extend) the results.

Since the accuracy of a POD expansion depends of course on the number N of initial simulations (the “snapshots”), the computational intensity of the method is certainly not negligible: but, as successfully demonstrated in the paper for a realistic CCGT inverse process design problem, the idea that additional full simulations are performed only in the “right direction” indicated by the gradient of the objective function in the solution space leads to a successful strategy at a substantially reduced computational intensity. This “economy” with respect to other classical “optimization” methods is basically due to the capability of the POD procedure to identify the most important “modes” in the functional expansion of the vector basis consisting of a subset of the design parameters used in the evaluation of the objective function.
Simulation and Optimization of a Semi Spherical Air Bearing
Authors: Saidimanesh Mahdi , Shahiri Azin , Nikparto Ali
Published: October 2013

It is important to test the attitude control systems on satellites before they are launched in space. Traditionally this has been done by dropping the satellite, and firing the thrusters before the satellite makes a soft landing in a net. This method only allows a few seconds of testing and does not lend itself to the measurement of pointing accuracy. A better method is to mount the satellite on a spherical air bearing.

In this paper behavior of a semi spherical air bearing is studied and analyzed in various conditions. These bearings are used in different applications such as simulation of approximately frictionless condition which is the satellite’s situation in space. In this analysis FLUENT 6.3.26 is used to simulate the air bearing’s behavior. Simulation process is divided into 5 sections. These sections are accordingly 2dimensional with static boundary condition, 3dimensional and static, 2dimensional and dynamic and 3dimensional and dynamic boundary conditions. At last bearing’s function was optimized by changing some adjustable parameters which are important in controlling the bearings behavior such as air entering nozzles diameter and their number and location. Importance of this study is to simulate the behavior of the bearing in dynamic boundary condition using dynamic mesh. Eventually results of the simulation are compared to the actual test results and bearing behavior is analyzed. Finally best arrangement for achieving maximum normal load is studied.
Micro-Texture Dependence of the Strength of Fine Metallic Bumps Used for Electronic Packaging
Authors: Endo Fumiaki , Murata Naokazu , Suzuki Ken , Miura Hideo
Published: October 2013

Electroplated copper bumps expected as fine metallic bumps for electronic packaging were investigated experimentally considering the change of micro texture dependence of their electroplating conditions and heat treatment after the electroplating. Not only Young’s modulus but also the strength of electroplated copper thin films changed drastically depending on the change of their micro texture, and these values were significantly different from conventional bulk copper. In addition, the strong anisotropy of Young’s modulus was observed between that along their thickness direction, and that parallel to their plane direction.
Fractional Derivative Viscoelastic Model for the Analysis of Two Colliding Spherical Shells
Authors: Rossikhin Yury A. , Shitikova Marina V.
Published: October 2013

The collision of two isotropic spherical shells is investigated for the case when the viscoelastic features of the shells represent themselves only in the place of contact and are governed by the standard linear solid model with fractional derivatives. Thus, the problem concerns the shock interaction of two shells, wherein the generalized fractional-derivative standard linear law instead of the Hertz contact law is employed as a low of interaction. The pans of the shells beyond the contact domain are assumed to be elastic, and their behavior is described by the equations of motion which take rotary inertia and shear deformations into account. The model developed here suggests that after the moment of impact quasi-longitudinal and quasi-transverse shock waves are generated, which then propagate along the spherical shells. Due to the short duration of contact interaction, the reflected waves are not taken into account. The solution behind the wave fronts is constructed with the help of the theory of discontinuities. To determine the desired values behind the wave fronts, one-term ray expansions are used, as well as the equations of motion of the contact domains for the both spherical shells.
Shock Interaction in Thermoelastic Rods With Temperature and Strain Coupling
Authors: Rossikhin Yury A. , Shitikova Marina V. , Shitikov Viktor V.
Published: October 2013

The problem of collinear collision of two thermoelastic rods with equal cross-section and rheological parameters but of different length and temperature is considered. Both rods move along the common longitudinal axes with different velocities, and one rod approaches the other. Their lateral surfaces and free ends are thermally insulated, and free thermal exchange is established via contacting ends. Thermoelastic behavior of the rods is described by the Green-Naghdy theory without energy dissipation, and D’Alembert solution is utilized as a method of solution. Since the coupling between the temperature and strain fields is assumed to be small, then the perturbation technique is used as well. The proposed procedure allows one to construct an analytical solution enabling to study the influence of thermoelastic parameters on the contact duration of two rods, as well as to obtain the stress, displacement velocity, temperature, and heat flow dependences of time and coordinate.
Energetic Efficiency Evaluation of a Town by Aerial Thermography
Authors: Dumas Antonio , Madonia Mauro , Trancossi Michele
Published: October 2013

This paper presents a preliminary study to evaluate energy dissipation of a town by the use of aerial thermography. The model has been realized for the town of Reggio Emilia taking into account the different optical and physical parameters which influences the infrared measurement. Altitude and operational speed are analysed on an optical point of view to minimize distortions of images and produce a sufficient resolution. By this analysis a parametric model has been defined.
Theoretical Modeling of the Oil–Gas Cyclone Separator in Oil–Injected Compressor Systems
Authors: Gao Xiang , Zhao Yaopeng , Feng Jianmei , Chang Yunfeng , Peng Xueyuan
Published: October 2013

This paper presented a simplified theoretical model of gas flow and particle motion in cyclone separator in oil-injected compressor based on the vortex flow equations. The tangential velocity distributions in cyclone separator for the top area and the bottom area have both been deduced by defining a pressure energy coefficient and the minimum oil droplet diameter been completely separated has been determined for variable separators. The separation efficiencies of different diameter oil droplets calculated by proposed model were compared with numerical simulation results using RSM model in gas flow field and DPM in oil droplet motion and the results were acceptable.
Investigation on a Gas-Liquid Ejector Using Three-Dimensional CFD Modeling
Authors: Kang Sanghoon , Song Xueguan , Kim Kyunghun , Park Youngchul
Published: October 2013

This work is focusing on the numeral study of a gas-liquid ejector used for ballast water treatment. The gas-liquid ejector is investigated through steady three-dimensional multiphase CFD analysis with commercial software ANSYS-CFX. Water as the primary fluid is driven through the driving nozzle and air is ejected into as the second gas instead of the ozone in real application. Several turbulence models such as Standard k-ε, RNG k-ε, SST, and k-ω, and different grid size are compared extensively with the experimental results to eliminate the influence of the auxiliary system. The appropriate numerical model in terms of the best combination of simplified 3D model, turbulence model and mesh size are used in the subsequent research to study the influence of the operating condition such as the driving pressure/velocity. And the proposed numerical model will be very helpful in the further design optimization of the gas-liquid ejectors.
An Investigation of Liquid Droplet Evaporation Model Used in Multiphase Flow Simulation
Authors: Ragab Reda , Wang Ting
Published: October 2013

Modeling liquid droplet evaporation in a flow stream is very important in many engineering applications. It was discovered that the result of predicted droplet and main flow temperatures from using commercial codes sometimes presents unexplainable phenomena; for example, the droplet temperature drops too low. The objective of this study is to investigate the issues involved in the built-in droplet evaporation model by using three different approaches: (a) use the existing built-in correlations model in a commercial code, (b) use the lumped analytical analysis, and (c) actually solve the heat and mass transfer by directly using CFD without employing the built-in correlation model. In the third approach, the evaporation process is simulated by imposing water evaporation in a very thin layer at the surface of a stagnant water droplet; in the meantime, the evaporation energy is subtracted from the same place. This is performed by imposing a positive mass source term and a negative energy source term in a thin layer of cells wrapping around the droplet surface. The transport equations are then solved using the commercial CFD solver Ansys/Fluent to track the mass and energy transfer across the shell sides into the liquid droplet and out to the ambient. Unlike the built-in evaporation model in commercial codes, which assumes that all the evaporation energy (latent heat) is supplied by the droplet, in the direct CFD calculation, the evaporation energy is absorbed partly from the droplet and partly from the surrounding air according to the natural process based on the property values and the heat and mass transfer resistance inside and outside the droplet. The direct CFD result (without using evaporation correlation) is consistent with that of the lumped analytical analysis (2nd approach). During the development of the direct CFD calculation, several technical difficulties are overcome and discussed in detail in this paper. A revised equation is proposed to improve the existing built-in model in the current commercial code. Both the direct CFD method and the zero-dimensional lumped method show the droplet temperature always increases.
Experimental and Numerical Investigation of Extrusion Die Profiles for Uniform and Effective Case-Hardening Treatment
Authors: Akhtar Syed Sohail , Arif Abul Fazal M.
Published: October 2013

One of the utmost challenges of hot aluminum extrusion is to design the die cavities, used to extrude thin-walled profiles, by considering the effective nitriding surface treatment of the die bearing surface in terms of nitride layer uniformity. In the present study, various AISI H13 steel samples (having commonly-used profile geometric features) are manufactured using wire EDM and subsequently nitrided using two-stage controlled nitriding treatment. The uniformity and depth of nitride layers formation on these are investigated in terms of compound layer and total nitride case depth using optical and scanning electron microscopes. Finite element code ABAQUS is used to simulate the nitrding process using sequentially coupled thermo-diffusive analysis in line with experimental set up. Both experimental and numerical results are found in close agreement in terms of nitrogen concentration and corresponding micro-hardness profiles. Some design modifications are implemented in FE code for critical die profile features for uniform nitride layer development. In view of the current results, some design guidelines are suggested for effective and uniform nitride layer formation in order to secure high quality extruded product and extended die life.
Determination of the Effective Diffusion Coefficient of Nano-Particles in Biological Tissue Using Simulation Method and Experimental Measurement
Authors: Yue Kai , Song Yang , Xu Peng , Zhang Xinxin
Published: October 2013

Based on the requirements of magnetic fluid hyperthermia for tumor therapy, the effective diffusion coefficient of nano-particles in biological tissue is numerically simulated using Monte-Carlo method when the treated tissues are considered as porous media. The simulation results are in good agreement with the data obtained from theoretical formula, and the validity of the proposed numerical simulation method is verified by the experimental data. The influences of the key structural factors on the effective diffusion coefficient are analyzed. Moreover, the corresponding experimental measurement is performed using the magnetic resonance imaging (MRI) method to obtain the effective diffusion coefficient of nano-magnetic fluid in biological tissue. The measured effective diffusion coefficient obtained by MRI measurement matches well with the simulation data. The results of this study may provide guidance for the study of transport phenomenon in biological tissues.
Wavelet-Based Damage Localization in Plate-Like Structures
Authors: Zhong Shuncong , Guo Jinquan , Yao Ligang , Zhuang Yizhou , Lu Huancai
Published: October 2013

The paper presented damage localization of plate-like structures using stationary wavelet transform (SWT) of displacement mode shapes. SWT is a redundant transform which doubles the number of input samples at each iteration. It provides a more accurate estimation of the variances and facilitates the identification of salient features in a signal, especially for recognizing noise or signal rupture. The displacement mode shapes of a cracked plate that contains a crack of small depth are essentially smooth surfaces. In reality, the mode shapes contain very small local peaks or discontinuities in the region of damage. However, it is difficult to identify and locate a crack directly from the graphical plot of the displacement mode shapes. Using SWT, mode shape curves can be decomposed into smooth, low order curves, called approximation coefficients, and wavy, high order curves called the detail coefficients, which include defect information that is useful for damage localization. The modal responses of the damaged fixed plates with a small crack ratio of 5% were computed using the finite element method (FEM). The results show that the SWT-based method has great potential in damage localization of plate-like structures as it does not require the modal parameter of an intact plate as a baseline for damage localization. Therefore, it can be recommended for real applications.
Natural-Ventilation Flow in a 3-D Room Fitted With Solar Chimney
Authors: Huynh B. P.
Published: October 2013

Natural-ventilation flow induced in a real-sized rectangular-box room fitted with a solar chimney on its roof is investigated numerically, using a commercial CFD (Computational Fluid Dynamics) software package. The chimney in turn is in the form of a parallel channel with one plate being subjected to uniform solar heat flux. Ventilation rate and air-flow pattern through the room are considered in terms of the heat flux for two different locations of the room’s inlet opening. Chien’s turbulence model of low-Reynolds-number K-ε is used in a Reynolds-Averaged Navier-Stokes (RANS) formulation. It is found that ventilation flow rate increases quickly with solar heat flux when this flux is low, but more gradually at higher flux. At low heat flux, ventilation rate is not significantly affected by location of the inlet opening to the room. On the other hand, at high heat flux, ventilation rate varies substantially with the opening’s location. Location of the inlet opening to the room also affects strongly the air-flow pattern. In any case, ample ventilation rate is readily induced by the chimney.
Flow Accelerated Corrosion in Single Bends Under Annular Two Phase Flow Conditions
Authors: Mazhar H. , Ewing D. , Cotton J. S. , Schefski C. , Ching C. Y.
Published: October 2013

The distributions of the mass transfer coefficient in horizontal 90 degree bends were measured under a range of two phase annular flow conditions. A dissolving wall technique at a high Schmidt number (Sc = 1280) is used for the measurements. The maximum mass transfer occurred on the centerline of the bend outer wall at an angle of approximately 50 degrees from the bend inlet under all tested conditions. The area of maximum mass transfer was found to span approximately 30 degrees in the circumferential direction. A second region of enhanced mass transfer occurred on the latter part of the bend with a local maximum occurring slightly off the bend centerline in some cases. Changing the air and water superficial velocities (Jν = 20 to 30 m/s, JL = 0.17 to 0.41 m/s) showed that the air velocity had a larger effect on the mass transfer than the water velocity; however the effect of the water velocity on the mass transfer was not insignificant.
System Reliability Estimation With Input Data From Deterministic Simulations
Authors: Pavasson Jonas , Karlberg Magnus
Published: October 2013

The possibility of estimating reliability of hardware, both for components and systems, is important in engineering design, since many failures result in substantial impact on safety or functional requirements. Existing reliability estimation methods require measured or estimated input data which can be difficult to retrieve. The objective of this paper is therefore to derive a simulation-driven method, including variation management, for combining deterministic simulations with Fault Tree Analysis, to estimate system reliability when measured data is not available.

The research work started with a literature survey followed by description of a typical as-is situation and definition of a to-be scenario. Then, a simulation-driven method was derived and verified by a case study. In particular, the system used for the case study was modeled and simulated as a transient dynamical system to derive information about loads on components. It was found that deterministic simulations can be used to produce relevant input data for fault tree analysis. The derived simulation-driven system reliability estimation method includes variation management and can be used for evaluation of concepts in the early stages of product development when limited measurement data is available.
Smooth Decomposition Analysis and Order Reduction of Nonlinear Mechanical Systems Under Random Excitation
Authors: Bellizzi Sergio , Sampaio Rubens
Published: October 2013

This paper presents a possible alternative procedure to the Karhunen-Loève approach to construct reduced order models which capture accurately the dynamics of nonlinear discrete mechanical systems under random excitation. This procedure combines the Smooth Decomposition method and the Petrov-Galerkin approximation. The smooth decomposition method is a multivariate-data analysis method characterizing coherent structures (the smooth modes) as the eigenvectors of the generalized eigenproblem defined from the covariance matrix of the displacement field and the covariance matrix of the velocity field. The Petrov-Galerkin approximation is used to project the dynamics in a subspace generated by a set of the smooth modes. The Petrov-Galerkin approximation preserves the second order structure of the equations of motion. The procedure is considered for a mechanical system including a strongly nonlinear end-attachment. The efficiency of the approach is analyzed comparing the power spectral density functions of the reduced-order model and of the original system.