bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Light Alternative-Powered Vehicle Use and Potential in the United States
Authors: Archibald Mark
Published: August 2012

Potential benefits of light alternative-powered vehicles are analyzed along with technical, social, and political factors affecting their widespread adoption in the United States. Light alternative-powered vehicles (LAV) include human-powered vehicles such as bicycles and velomobiles, electric bicycles, light electric vehicles, hybrid human-electric, and similar vehicles. Currently bicycles comprise the vast majority of this class of vehicle. Widespread adoption of light alternative-powered vehicles can result in reduced transportation energy consumption, reduced greenhouse gas emissions and air pollution, reduced urban noise, and reduced user costs. Annually, the average US driver could reduce gasoline consumption by 2000 liters, greenhouse gas emissions by 4 metric tonnes, and realize an annual savings of $5,000. In the United States the use of light alternative vehicles is quite low, due primarily to a combination of social, economic, and political factors, including transportation regulations. While dramatic increases in the use LAVs is not likely without changes in these factors, technological factors may significantly affect perception and use. Significant technical factors include improved batteries and control systems, reduced manufacturing cost, improved usability, and improved infrastructure. Scale is an important factor. Most of the technical factors are solvable with current or emerging technologies, but the demand for LAVs the United States does not justify the investment required. Light alternative-powered vehicles have the potential be a significant part of energy and GHG policy in the United States, but are limited more by political factors than by technology.
Novel Application of Optical Density Technique to Evaluation of Corrosion Behavior of Metallic Thin Films
Authors: Kotoka Ruben , Yarmolenko Sergey , Pai Devdas , Sankar Jag
Published: August 2012

Bulk nanostructured metallic alloys as well as coatings are being research closely for biomedical applications, especially for implants. Corrosion behavior is of particular interest, given the aggressive environment of body fluids that these metals experience. While weight loss measurement and electrochemical analysis are the two commonly used techniques for corrosion behavior evaluation, both have their own limitations with respect to characterizing the corrosion of films and coatings under a micron in thickness. This paper reports on a novel application of the optical density technique as a relatively faster yet accurate method to evaluate the corrosion of thin metallic films. With this technique, the survivability and/or resorption time of a pure metallic coating is evaluated by monitoring the changes in optical density (directly related to reduction in film thickness, and thereby to weight loss) of thin film immersed in a corrosive media. In our experiments, Mg, Cu and Ag thin films of a wide range of thicknesses were sputter-deposited on glass substrates and the corrosion kinetics of these metals in a simulated body fluid was studied at room temperature. The results were utilized to develop a resorption time model for the coating, which can be used to predict the survivability of these metallic thin films.
Thermal-Mechanical Response of Non-Uniformly Heated LEU Foil Based Target
Authors: Turner Kyler K. , Solbrekken Gary L. , Allen Charlie W.
Published: August 2012

Technetium-99m is a diagnostic radiopharmaceutical that is currently used in 80% of the global nuclear diagnostic imaging procedures. The parent isotope for technetium-99m is molybdenum-99, most commonly obtained through the irradiation of high enriched uranium (HEU) targets. In accordance with the Department of Energy’s Global Threat Reduction Initiative (GTRI) an effort is underway to develop a process to produce molybdenum-99 using low enriched uranium (LEU) targets to maintain production yield relative to HEU targets. Conversion of targets to LEU material effectively mandates that the most efficient process is to cast LEU in the form of a metal foil as opposed to current powder based dispersion designs for HEU. Using a foil requires a significant modification to the current target design. One design concept uses an LEU foil sandwiched between two nominally flat aluminum plates. The LEU is enclosed in the sandwiched structure by welding the aluminum plates together about their edges. The plate design is inspired by high density monolithic LEU fuel plates with the exception that the LEU is not bonded to the aluminum plates nor is it necessary to clamp the plate edges to prevent lateral translation. The lack of bonding between the LEU foil and the plates allows the edges of the plate to be cut off so the foil can be removed after irradiation to be chemically processed. The un-heated edges of the plate target produce 3-D temperature gradients that induce plate deformations. This paper will review thermal mechanical response of an LEU foil based molybdenum-99 plate target geometry. This study describes the effect of various edge holding conditions, thermal loads, and heat transfer coefficients on the thermal-induced deflection and stress in the plates.
Molecular Dynamics Simulation of Thermal Accommodation Coefficients for Laser-Induced Incandescence Sizing of Nickel Nanoparticles
Authors: Daun K. J. , Karttunen M. , Titantah J. T.
Published: August 2012

While time-resolved laser-induced incandescence is most often used to characterize the size and concentration of aerosolized carbonaceous particles, it has recently been applied to aerosols containing metal nanoparticles. This calculation requires the thermal accommodation coefficient, however, which is often difficult to determine experimentally. This paper presents a molecular dynamics investigation of the thermal accommodation coefficient between laser-energized nickel nanoparticles immersed in argon, and the underlying the gas-surface scattering physics. The predicted interaction between gas molecules and the laser-energized surface depends strongly on the potential between the gas molecule and a surface atom: a Lennard-Jones 6–12 potential derived using the Lorentz-Berthelot combination rules overestimates the potential well due to a bond-order effect in the nickel, resulting in strong trapping-desorption and near-perfect thermal accommodation. A Morse potential with parameters obtained directly from ab initio free energies predicts a relatively brief interaction between the gas molecule and nickel surface, on the other hand, and a lower thermal accommodation coefficient similar to experimentally-derived values for laser-energized iron nanoparticles in argon reported in the literature.
Multi-Mode Vibration Energy Harvester and Tuned Mass Damper Using Double-Beam Structure
Authors: Zhou Wanlu , Penamalli Gopinath Reddy , Zuo Lei
Published: August 2012

A novel piezoelectric energy harvester with multi-mode dynamic magnifier is proposed and investigated in this paper, which is capable of significantly increasing the bandwidth and the energy harvested from the ambient vibration. The design comprises of an multi-mode intermediate beam with a tip mass, called “dynamic magnifier”, and an “energy harvesting beam with a tip mass. The piezoelectric film is adhered to the harvesting beam to harvest the vibration energy. By properly designing the parameters, such as the length, width and thickness of the two beams and the weight of the two tip masses, we can virtually magnify the motion in all the resonance frequencies of the energy harvesting beam, in a similar way as designing a new beam-type tuned mass damper (TMD) to damp the resonance frequencies of all the modes of the primary beam. Theoretical analysis, finite element simulation, and the experiment study are carried out. The results show that voltage produced by the harvesting beam is amplified for efficient energy harvesting over a broader frequency range, while the peaks of the first three modes of the primary beam can be effectively mitigated simultaneously. The experiment demonstrates 25.5 times more energy harvesting capacity than the conventional cantilever type harvester in broadband frequency 3–300Hz, and over 1000 times more energy close to the first three resonances of harvesting beam.
Multijet Impingement on Pin Fin Heat Sink With Different Crossflow Schemes
Authors: Chougule Nagesh K. , Parishwad Gajanan V. , Pagnis Sachin , Gore Prashant R.
Published: August 2012

The fluid flow and heat transfer characteristics of multi air jet array impinging on a 4×4 pin fin heat sink with 3×3 nozzle arrays are investigated both numerically and experimentally. The results for multi jet impingement with wide range of parameters are not readily available in the literature. Different exit flow conditions such as minimum, semi and maximum cross flow conditions are simulated using shear stress transport (SST) k-ω turbulence model to study the combined effects of Reynolds number (Re) and spacing between nozzle exit and target surface (Z/d) on heat transfer coefficient (havg). The jet Reynolds number is varied from 7000 to 50000 and Z/d is varied from 6 to 10. For Re ≤ 18000, it is noticed that the minimum cross flow scheme gives maximum heat transfer, than semi cross flow and the maximum cross flow schemes at all Z/d considered here. Semi cross flow scheme works better for Re ≥ 18000. At Re = 11000 the minimum cross flow scheme indicates that Nua decreases from 50.1 to 36.41 with increase in Z/d from 6 to 10. It is also observed that the symmetry of the heat transfer patterns occur in the minimum and semi cross flow schemes as the sidewalls restrict the flow in opposite direction. However, in the maximum cross flow scheme, the stagnation peaks shifted and reduced in the stream wise direction by the strong cross flow degradation.
Selection of CFD Turbulence Model for the Application of Submerged Multi-Air Jet Impingement
Authors: Chougule Nagesh K. , Parishwad Gajanan V. , Pagnis Sachin , Gore Prashant R. , Sewatkar Chandrashekhar M.
Published: August 2012

Most impinging jet industrial applications involve turbulent flow in the whole domain downstream of the nozzle, and modeling turbulent flow presents the greatest challenge in the effort to rapidly and accurately predict the behavior of turbulent jets. Numerical modeling of impinging jet flows and heat transfer is employed widely for prediction, sensitivity analysis, and device design. Finite volume computational fluid dynamics (CFD) models of impinging jets have succeeded in making good predictions of heat transfer coefficients and velocity fields. The difficulties in accurately predicting velocities and transfer coefficients stem primarily from modeling of turbulence and the interaction of the turbulent flow field with the wall. In present work, the flow and heat transfer characteristics of circular multi jet array (3×3) of 5mm diameter impinging on the Flat plate heat sink are numerically analyzed based on the CFD commercial code ANSYS CFX. The relative performance of four different turbulence models, including Standard k-ε, RNG k-ε, (Renormalization Group), Standard k-ω and SST (Shear-Stress Transport) k-ω models are done for the prediction of this type of flow and heat transfer is investigated by comparing the numerical results with experimental data. It is found that SST k-ω model gives better predictions with moderate computational cost. Using SST k-ω model, the effect of Reynolds number (Re) on the average Nusselt number (Nua) of target plate is examined at Z/d = 6 (Z/d is the gap between nozzle exit and target surface).
Study of Bubbly Flow Through a Packed Bed
Authors: Jo Daeseong , Revankar Shripad T.
Published: August 2012

A two phase bubbly flow through a packed bed was studied for dominant bubble breakup and coalescence mechanisms through experiments and CFD modeling. Data on various two-phase parameters, such as local void fraction, bubble velocity, size, number, and shape were obtained from the high speed video images. Results indicated that when a flow regime changed from bubbly to either trickling or pulsing flow, the number of average size bubbles significantly decreased and the shape of majority of bubbles was no longer spherical. The bubble coalescence and breakup mechanisms depend on local conditions such as local velocity of the bubble and pore geometry. The CFD analysis using CFX software package was carried out to study bubble size distributions. In the analysis the models for interactions were examined for each case of bubble breakup flow and bubble coalescence. A comparative study was performed on the resulting bubble size distributions, breakup and coalescence rates estimated by individual models. For change of bubble size distributions along the axial direction medians was used as an comparative parameter and the CFD results on bubble medians were compared against the experimental data. This comparative study showed that the predictions estimated by CFD analyses with the bubble breakup and coalescence models currently available in the literature do not agree with the experimental data.
An Automated Structural Health Monitoring System
Authors: Hasan Zeaid , Hasweh Fares , Al-Nadi Omar Abu , Atmeh Ghassan
Published: August 2012

Structural health monitoring (SHM) is the process of implementing a damage identification strategy which can be utilized in several applications including aerospace, civil and mechanical engineering infrastructure. Damage is defined as changes to the material and/or geometric properties of these systems. These changes adversely affect the current or future performance of the system. In order to identify damage in a suitable and meaningful manner, the damaged state is compared with other usually undamaged states. This study focuses on a structural health monitoring (SHM) system based on detecting shifts in natural frequencies of the structure. This structural health monitoring system incorporates a low power wireless transmitter that sends a warning signal when damage is detected in a structure. The damage detection technique is implemented on composite structures which are widely used in many applications including aeronautical and aerospace. An automated damage detection system capable of providing information of damage locations based on the finite element analysis and able to compare damage events to other historical data is also proposed in this paper and initially implemented using a microcontroller chip. Moreover, a control methodology using piezoelectric fiber composites, such as active fiber composites (AFCs) and microfiber composites (MFCs), is included as part of the system for vibration suppression purposes. The advantages of using piezoelectric fiber composite actuators are their high performance, flexibility, and durability when compared with the traditional piezoceramic (PZT) actuators. The proposed system may be implemented in many structural components such as aircraft frames and bridges. This SHM technology may help replace the current time-based maintenance scheme with a condition-based one. The condition-based maintenance scheme relies on the ability to monitor the condition of the system and supply information of damage detection to allow a corrective action to be taken.
Fast Copper Plating Process for Through Silicon Via (TSV) Filling
Authors: Wang Su , Lee S. W. Ricky
Published: August 2012

There is an increasing demand for electronic devices with smaller sizes, higher performance and increased functionality. The development of vertical interconnects or through silicon vias (TSV) may be one of the most promising approaches to provide the three-dimensional (3D) integration of integrated circuits (IC). It is possible to improve the system’s performance with shorter RC delay, shorter signal paths and less power consumption. Electroplating process is one of the major contributors to the cost of TSV. Thus, plating time is one of our major concerns in TSV applications. About 80% of the TSVs are filled with copper due to its high conductivity and wide applications in multilayer wiring. Even though the electroplating of copper for interconnections is well established for the copper damascene micro-fabrication process, it has been shown that the filling of TSVs with copper plating is a different situation due to the much larger dimensions of TSVs. Generally the filling mechanism consists of conformal plating and bottom up plating. A 100% bottom up filling is preferred for copper filling in TSV. A seam may exist in via if the majority of filling mechanism is conformal plating. Thus, the bottom up filling profile is one the critical points to achieve void free filling. In this study, the void free copper filling TSVs with diameter from 10–30 m and depth from 50–150 m will be investigated by copper electroplating. A near 100% bottom up plating formula was developed in order to achieve void free and seam free filling. Filling performance of this plating formula was evaluated by examining vertical cross-sections and top-down cross-section of the filled TSVs using optical microscope and X-ray method. Pretreatment process and relationship with diffusion time will be also studied with respect to the TSV plating process. The effect of concentration of copper, acid and additives will be optimized to achieve the desired bottom up plating process. The ultimate goal is to achieve TSV plating with shorter plating time and better consistency. Electroplating experiment was conducted with an industrial electroplating tool. Successful plating results are demonstrated with optimized plating bath and plating mechanism. The void free and seam free copper deposition results are shown with minimized overburden. The time taken for the plating process is also greatly reduced with this near 100% bottom up plating formula. The benefits of this novel plating mechanism will be discussed in detail in this paper.
Thermal Conductivity of Crystalline Nanoporous Silicon Using Molecular Dynamics Simulations
Authors: Fang Jin , Pilon Laurent
Published: August 2012

This study establishes that the effective thermal conductivity keff of crystalline nanoporous silicon is strongly affected not only by the porosity fv and the system’s length Lz but also by the pore interfacial area concentration Ai. The thermal conductivity of crystalline nanoporous silicon was predicted using non-equilibrium molecular dynamics (NEMD) simulations. The Stillinger-Weber potential for silicon was used to simulate the interatomic interactions. Spherical pores organized in a simple cubic lattice were introduced in a crystalline silicon matrix by removing atoms within selected regions of the simulation cell. Effects of the (i) system length ranging from 13 to 130 nm, (ii) pore diameter varying between 1.74 and 5.86 nm, and (iii) porosity ranging from 8% to 38%, on thermal conductivity were investigated. A physics-based model was also developed by combining kinetic theory and the coherent potential approximation. The effective thermal conductivity was proportional to (1–1.5fv) and inversely proportional to the sum (Ai/4+1/Lz). This model was in excellent agreement with the thermal conductivity of nanoporous silicon predicted by MD simulations for spherical pores (present study) as well as for cylindrical pores and vacancy defects reported in the literature. These results will be useful in designing nanostructured materials with desired thermal conductivity by tuning their morphology.
Performance Assessment of Single Electrode-Supported Solid Oxide Cells Operating in the Steam Electrolysis Mode
Authors: Zhang X. , O’Brien J. E. , O’Brien R. C. , Petigny N.
Published: August 2012

An experimental study has been conducted to assess the performance of electrode-supported solid-oxide cells operating in the steam electrolysis mode for hydrogen production. Results presented in this paper were obtained from single cells, with an active area of 16 cm2 per cell. The electrolysis cells are electrode-supported, with yttria-stabilized zirconia (YSZ) electrolytes (∼10 μm thick), nickel-YSZ steam/hydrogen electrodes (∼1400 μm thick), and modified LSM or LSCF air-side electrodes (∼90 μm thick). The purpose of the present study is to document and compare the performance and degradation rates of these cells in the fuel cell mode and in the electrolysis mode under various operating conditions. Initial performance was documented through a series of voltage-current (VI) sweeps and AC impedance spectroscopy measurements. Degradation was determined through long-term testing, first in the fuel cell mode, then in the electrolysis mode. Results generally indicate accelerated degradation rates in the electrolysis mode compared to the fuel cell mode, possibly due to electrode delamination. The paper also includes details of an improved single-cell test apparatus developed specifically for these experiments.
Single- and Two-Phase Flow in Microchannels With Heat Transfer and Driven by an EHD Conduction Pump
Authors: Pearson Matthew R. , Seyed-Yagoobi Jamal
Published: August 2012

Microchannels have well-known applications in cooling because of their ability to handle large quantities of heat from small areas. Electrohydrodynamic (EHD) conduction pumping at the micro-scale has previously been demonstrated to effectively pump dielectric liquids through adiabatic microchannels by using electrodes that are flushed against the walls of the channel. In this study, an EHD micropump is used to pump liquid within a two-phase loop that contains a microchannel evaporator. Additional EHD electrodes are embedded within the evaporator, which can be energized separately from the adiabatic pump. The enhancement effect of these embedded electrodes on the heat transport process in the micro-evaporator and on the two-phase loop system is characterized. Single- and two-phase heat transfer regimes are both studied and the effect of applied voltage and heat flux are considered on the overall flow rate and the wall temperature of the microchannel.
Flow Signal Characteristics of an Ultrasonic Transducer at a High Temperature
Authors: Lim Ki Won , Rho Jaeheun
Published: August 2012

The exact measurement of feed water flow is the major factor in nuclear power plant efficiency. However, due to the fouling problem, the venturi nozzle used in feed water measurement frequently causes a decrease in the efficiency of the nuclear power plant. To avoid this problem, ultrasonic technology is a reasonable candidate. The temperature of the feed water is about 300 °C. The commercial piezoelectric element used in an ultrasonic transducer preserves its characteristics up to a temperature of 120 °C. This problem must be overcome in order to use an ultrasonic flowmeter to measure the feed water flow. To address this issue, we designed a thermal block to insulate the high temperature from the pipe line. The method we used included a clamp-on type transducer and a driving circuit with a transit time difference method. The signals from the driving circuit were measured and the ultrasonic transducer assembly was tested at room temperature and at a high temperature of 300 °C. The test results revealed that the transit time difference was reasonably proportional to the flow velocity at room temperature, and the signals of the transducer installed on the pipe line were the same at 300 °C as those at room temperature. This result confirmed that the ultrasonic pulse was working well through the thermal block and in the high temperature fluid.
Problem Solving in Mechatronic Competency Training Related to Field Practice
Authors: Sierota Andzrej B. , Kłapyta Grzegorz , Gustowski Jerzy
Published: August 2012

Global economy and growing competiveness on international market require consolidated approach in the Problem Solving process, that cover a variety of issues and functions in social life and economy; also in vocational education and industrial training [1]. The paper outlines a concept of Competence Based Problem Solving Training Protocol for modular mechatronic training by DATAMAS, developed to upgrade mechatronic competence of staff performing maintenance and repair jobs in automated plants in Poland. The concept presumes, that to achieve the very best training outcomes resulting in fast and effective diagnose and solving field problems, it is necessary to better adjust specialized training curricula and procedures to the problem of staff intellectual potential and capability. Such approach is reflected in the process of delivering DATAMAS training modules, flexible and adaptable to different production systems and conditions thus, able to effectively upgrade the maintenance staff competences and solve a variety of functional and other problems. Due to their didactic content combining knowledge and hard skills acquisition as well as soft skills, behaviors and attitudes advancement, the modules are the base training material, modified and applied for a variety of customized, on demand training courses “on the shop-floor”. They exercise how to more effectively solve real field problems by engaging trainees to some creative activity and emotional involvement. The modules are equipped with DATAMAS Training Protocol which provides methodological and organizational frame for the company’s trainers. DATAMAS Training Protocol was designed to follow the SSM approach [2]. The Protocol is mapping many functional features and training procedures that follow technical program saturated with the ongoing “mind storm” animation and argumentation. Since the DATAMAS Training Protocol concept has been under continuing scrutiny, only some limited data on its application are available. The paper outlines the concept, discus the problem solving cycle applied and explains some features of the Protocol. Problem solving cycle proposed by DATAMAS is outlined in Annex A, while a section of DATAMAS Training Protocol is shown in Annex B.
Development of an OpenSim Shoulder Model for Manual Wheelchair Users With Tetraplegia
Authors: Odle Brooke , Forrest Gail , Reinbolt Jeffrey , Dyson-Hudson Trevor
Published: August 2012

Extended manual wheelchair use has been associated with repetitive strain injuries in the shoulder and has been identified as a contributing factor to upper limb pain experienced by manual wheelchair users with spinal cord injury (SCI) [1]. Due to the nature of their SCI, individuals with tetraplegia (formerly quadriplegia) may be at an even greater risk for developing shoulder injuries because they often have only partial innervation of their shoulder, scapular, and thoracohumeral muscles [2].
Springback Evaluation of Parts Made by Single-Point Incremental Sheet Forming
Authors: Bosetti Paolo , Bruschi Stefania
Published: August 2012

One of the major drawbacks of single-point incremental forming process for sheet metal (SPIF) consists in the poor geometrical accuracy of formed parts. This limits the use of SPIF technology and has pushed the development of alternative incremental processes—such as the two-points incremental forming—aimed at improving the forming accuracy. However, these processes require the use of supporting dies and they therefore reduce the competitive advantage of SPIF process. The possibility to compensate for part springback, in order to have the part geometry as close as possible to the nominal one, represents one of the major challenges to make SPIF process suitable for real industrial applications. However, any possible approach in springback compensation must pass through the comprehension of the springback phenomenon. The objective of the paper is to analyze the springback of parts made by SPIF, by evaluating the influence that elastic recovery before and after the part unclamping has on the final part geometry. A SPIF experimental campaign was carried out on a truncated pyramid as case study, by varying both the part geometrical parameters (the wall angle and the height), and the process parameters (the tool step-down size and the feed rate). The material used in this study was the duplex steel DP600 provided in 0.8 mm thick sheets. After forming—but before unclamping—the part geometry was measured by means of of an electronic touch probe mounted on the machine tool-holder, in order to investigate the elastic recovery due to the successive tool laps. After unclamping, the part geometry was measured on a coordinate measuring machine. The influence of geometrical and process parameters was analyzed and the contribution of elastic recovery before and after the part unclamping was assessed.
Dynamic Characteristic of an Artificial Wing Mimicking a Beetle Hind Wing
Authors: Ha Ngoc San , Goo Nam Seo , Jin Tailie , Nguyen Quoc Viet , Park Hoon Cheol
Published: August 2012

Biomimetics is one of the most important paradigms as researchers seek to invent better engineering designs over human history. However, the observation of insect flight is a relatively recent work. Several researchers have tried to address the aerodynamic performance of flapping creatures and other natural properties of insects, although there are still many unsolved questions. In this study, we have attempted to investigate the structural dynamic characteristic of an artificial wing that mimicked the wing shape and main venation structure of a beetle hind wing using a non contact measurement method. The structural dynamic characteristic of the artificial wing was measured and compared to the real beetle hind wing by determining the natural frequencies and damping factor. The artificial wing was glued with the cyanoacrylate adhesive at the wing base onto the acrylic stand which was attached to the base of a shaker. The shaker produces the translation motion in the lateral direction of the wing plane. A non-contact laser sensor was used to measure the displacement history of the painted spots on the hind wing. A Bru¨el & Kjær FFT analyzer was adopted to calculate the frequency response functions where the natural frequencies of the wing structure can be extracted. The fundamental natural frequency of artificial wing is 51.3 Hz while the natural frequency of the beetle hind wing is 48.8 Hz. In addition, the wing structures were lightly damped with damping factor around 3.1% that is close to the one of beetle hind wing. We found that, in terms of the wing elasticity, the plastic wing frame of artificial wing was suitable for beetle-like flight.
In Situ Characterization of Coal Ash Thermal Conductivity Under Oxidizing and Reducing Conditions
Authors: Cundick D. , Maynes D. , Moore T. , Tree D. R. , Jones M. R. , Baxter L. L.
Published: August 2012

This work presents in situ measurements of the effective thermal conductivity in particulate coal ash deposits under both reducing and oxidizing environments. Laboratory experiments generated deposits on an instrumented deposition probe of loosely-bound particulate ash from three coals generated in a down-fired flow reactor with optical access. An approach is presented for making in situ measurements of the temperature difference across the ash deposits, the thickness of the deposits, and the total heat transfer rate through the ash deposits. Using this approach, the effective thermal conductivity was determined for coal ash deposits formed under oxidizing and reducing conditions. Three coals were tested under oxidizing conditions: two bituminous coals derived from the Illinois #6 basin and a subbituminous Powder River Basin coal. The subbituminous coal exhibited the lowest range of effective thermal conductivities (0.05–0.18 W/m· K) while the Illinois #6 coals showed higher effective thermal conductivities (0.2–0.5 W/m· K). One of the bituminous coals and the subbituminous coal were also tested under reducing conditions. A comparison of the ash deposits from these two coals showed no discernible difference in the effective thermal conductivity based on stoichiometry. All experiments indicated an increase in effective thermal conductivity with deposit thickness, probably associated with deposit sintering.
The Nonlinear Finite Element Analysis of a Novel Dental Implant With an Interposed Internal Layer Imitating Periodontal Ligament’s Function
Authors: Ahmadian Mohammad Taghi , Firoozbakhsh Keikhosrow , Ghanati Golsa , Ghanati Parsa
Published: August 2012

Osseointegrated dental implants are deficient in natural periodontal ligaments. It may therefore, disrupts the natural function of implant and leads to excessive stress and strain in jaw bone. Our new proposed implant has the nonlinear internal component which imitates periodontal ligaments function. A nonlinear finite element analysis developed to investigate the efficiency of utilizing this nonlinear internal layer for three conditions of bone implant interface conditions under vertical and horizontal loading conditions. Our results so far indicate that the use of a class of material exhibiting incompressible hyperelastic behaviour as a internal layer can reduce the peak stress deduced from different loads. The mobility of implant supported prosthesis is similar to that of natural tooth and micromotion at the bone-implant interface is decreased for both delayed and immediately loading treatment.
Ultrasound Viscoelastic Imaging of Breast Lesions: A Practical Hybrid Freehand Technique for Data Acquisition
Authors: Di Battista Andrew , Noble J. Alison , English Ruth
Published: August 2012

Ultrasound imaging of the breast is a standard method in breast cancer screening, along with mammography. The viscoelastic properties of soft tissue can provide supplementary information for radiologist to consider in their assessment of pathology and tissue characterization. Measuring these properties generally entails acquiring a time sequence of ultrasound images and calculating parametric data from it. As images are necessarily accumulated over time, acquisition is limited by the frame rate and memory capacity of the ultrasound machine, and practical considerations such as movement from the clinicians hands and patient breathing. This paper describes a technique for hybrid-freehand imaging of viscoelasticity (HYFIVE). It involves acquiring a time sequence of images making use of a simple purpose built canister enclosure for the ultrasound probe which allows for a stable and accurate manipulation of applied forces, without the need of motors, sensors or other sophisticated and costly parts. A sequence of ultrasound strain images was computed and a first order Kelvin-Voigt tissue model fit to the resulting strain vs. time curves to obtain parametric data related to tissue stiffness and viscosity. Experiments were conducted on both gelatin phantoms and clinical patient data.
Integrated Vehicle Control Based on Tire Force Reserve Optimization Concept
Authors: Peng Huei , Sabahi Rahman , Chen Shih-Ken , Moshchuk Nikolai
Published: August 2012

Integrated vehicle control (IVC) (also known as Integrated Chassis Control (ICC)) is a key technology for vehicle active safety. The basic concept of IVC is to allocate chassis actuations coherently to control vehicle dynamics in longitudinal and lateral directions simultaneously. Even when only the four brake inputs are considered, the IVC problem is over-determinant. In other words, it must be solved as an optimization problem. In this paper, the optimization goal is to achieve best “tire force reserve”, defined as the difference between the tire force capacity and the resultant tire force. This optimization formulation achieves uniform utilization of tire forces and thus better robustness against normal force and road roughness disturbances. Simulation results are presented to demonstrate the basic idea of this approach.
Compact Model of Thermoelectric Coolers on a Micro-Electronic Chip
Authors: Sullivan Owen , Alexandrov Borislav , Mukhopadhyay Saibal , Kumar Satish
Published: August 2012

Hot spots on a microelectronic package can severely hurt the performance and long-term reliability of the chip. Thermoelectric coolers (TECs) have been shown to potentially provide efficient site-specific on-demand cooling of hot spots in microprocessors. TECs could lengthen the amount of time a processor is capable of running at full speed in the short-term and also provide long-term reliability by creating a more uniform temperature distribution across the chip. We have created a compact model for fast and accurate modeling of the TEC device integrated inside an electronic package. A 1-D compact model for TEC is first built in SPICE and has been validated for steady-state and transient behavior against a finite-volume model. The 1-D model of TEC was then incorporated into compact model of a prototype electronic package and simulations were performed to validate its steady state and transient behavior. This integrated compact model’s results are in good agreement with a finite volume based model developed for TECs integrated inside a package and confirmed the compact model’s ability to accurately model the TEC’s interaction with package. The compact model has relatively small error when compared to the finite-volume based model and obtains results in a fraction of the time, reducing run-time in a transient simulation by 430%. A simple controller was added to the electronic package and TEC model to provide an initial test of how the compact model can aid design of more complex control systems to efficiently operate the thermoelectric coolers.
Slip-Based Holistic Corner Control
Authors: Pylypchuk Valery , Chen Shih-Ken , Moshchuk Nikolai , Litkouhi Bakhtiar
Published: August 2012

This paper describes an analytical methodology and related algorithms for controlling vehicle tire forces. The purpose of control is to provide a driver with a normal driving feel and keep the vehicle on a target path even under poor road conditions. All the control variables are calculated in real time by minimizing the error between actual and target CG forces and moments. Such a real time optimization is possible due to the availability of analytical solutions for the tire force adjustments derived in the matrix form. A key ingredient of the approach is the idea of constructing weight matrices dependent upon tire states after the optimal linear solution is obtained. When a tire reserve approaches its upper limit, the corresponding weight element increases exponentially. As a result, this stability element dominates the gradient of the target function regardless of CG force error magnitudes. Once the tire state becomes normal then the CG force error correction again becomes the dominant component in the control solutions.
Numerical Solution of a Transient Flow in Hydraulic Power Plant Systems Using Hydroacoustic Modeling Method
Authors: Taklifi A. , Riasi A. , Nourbakhsh S. A.
Published: August 2012

This paper analyses the discrete hydraulic systems with emphasis on hydraulic parameter analysis for a pump-turbine power plant. The developed model could make hydro-electric power plants transient behavior studies more easy and accurate, especially for complicated systems. The simulation was developed based on analog mathematical models of transient phenomenon equations (Hydroacoustic modeling). In this method, the governing equations for transient flows are solved based on equivalent electrical circuits being defined for different equipments of the system. By using the Kirchhoff’s voltage law for the final equivalent circuit of the system a set of nonlinear ordinary differential equations is generated. The unsteady friction loss and visco-elastic behavior of pipe and fluid are considered in the pipelines model. A set of nonlinear ordinary differential equations is generated by using an implicit scheme. These equations of nonlinear ODEs are solved using a fourth order Runge-Kutta method. Further validation has been carried out with experimental values. Also a mathematical model for Francis pump-turbine has been developed and the transient behavior of two different cases of hydraulic systems including the pump-turbine has been investigated. The results were logically correct and acceptable. This method is very efficient for overall simulation of hydro power plants including turbine, generator and transformer.
Reduced Degrees-of-Freedom of the Nonlinear Dynamics of Elastic Pipelines for Airborne Refueling
Authors: Georgiou Ioannis T. , Chatjigeorgiou Ioannis K.
Published: August 2012

It is the purpose of this study to investigate the principal nonlinear dynamic phenomena associated with the dynamic behavior of elastic suspended pipelines transporting fuels for refueling of aircrafts. The pipe is modeled as a slender beam that obtains a catenary configuration between the end points, i.e. the connections between the tanker and the refueled aircraft. In the specific arrangement the excitation is mainly induced due to the 3D motions of the connected aircrafts and is imposed in both ends of the pipeline. A characteristic feature of the investigated operation is the lack of a large damping component that could cancel potential instabilities. In the present study, the pipeline is considered as a continuous media and its dynamic problem is expressed through the complete nonlinear system of partial differential equations which are derived following a Newtonian derivation. The model adopted for describing the inner flow is the so called “plug-flow model”. The system is treated as a two point boundary value problem and it is solved in the time domain to trace all possible nonlinearities. To tackle the details of the nonlinear modes of motion the output signals of the dynamic response, that provide all governing dynamic components, namely, motions, inner loading terms, bending moments and angles of rotation, are further elaborated by the POD method. The POD Transform provides insight into the reduced order dynamics of this geometrically nonlinear exact coupled dynamical system.
Thermoelectric Transport in Sb2Te3/Bi2Te3 Quantum Dot Nanocomposites
Authors: Zhou J. , Yang R. G.
Published: August 2012

We investigate the thermoelectric transport properties of Sb2Te3/Bi2Te3 quantum dot nanocomposites with spherical Sb2Te3 quantum dots arrays embedded in Bi2Te3 matrix through a two-channel transport model. In this model, the transport of quantum-confined electrons through the hopping mechanism is studied by tight-binding model together with Kubo formula and Green’s function method. The formation of minibands due to the quantum confinement and the phonon-bottleneck effect on carrier-phonon scattering are considered. The transport of bulk-like electrons is studied by Boltzmann-transport-equation-based model. We consider the intrinsic carrier scatterings as well as the carrier-interface scattering of these bulk-like electrons. Thermoelectric transport properties are studied with different quantum dot sizes, inter-dot distances, doping concentrations, and temperatures. We find that electrical conductivity and Seebeck coefficient can be enhanced simultaneously in Sb2Te3/Bi2Te3 quantum dot nanocomposites because of the formation of minibands and the phonon-bottleneck effect on carrier-phonon scattering. Our results could shed some light on the design of high-efficiency thermoelectric materials.
Thermal Transport Across Carbon Nanotube Connected by Molecular Linkers
Authors: Liu Jun , Alhashme Mohamed , Yang Ronggui
Published: August 2012

Carbon nanotubes (CNTs) have been reported to have excellent thermal and mechanical properties over the past two decades. However, the practical application of CNT-based technologies has been limited, due to the inability to transform the excellent properties of single CNTs into macroscopic applications. CNT network structure connects CNTs and can be possibly scaled up to macro-scale CNT-based application. In this paper, nonequilibrium molecular dynamics is applied to investigate thermal transport across two CNTs connected longitudinally by molecular linkers. We show the effect of different types and lengths of molecular linkers on interfacial thermal conductance. We also analyze the density of vibrational normal modes to further understand the interfacial thermal conductance between different molecular linkers and CNTs. These results provide guidance for choosing molecular linkers to build up large-scale CNT-based network structures.
Phase Transitions of Granular Systems: Between Brazilian Nut Effect and its Reversed Mode
Authors: Xie Zi’ang , Wu Ping , Zhang Shiping , Jia Chao , Wang Weili
Published: August 2012

Granular particles with diameters 3mm, 6mm and 0.6mm, of the same density 0.9g/cm3 and the same total weight 100g in vertically vibrating systems were studied. The transition processes of granular systems from Reversed Brazilian Nut (RBN) Effect to Brazilian Nut (BN) Effect at varied conditions, including different vibrating frequencies, amplitudes, and particles sizes, together with computer simulations were investigated. We have observed experimentally that BN Effect or RBN Effect was appeared at certain particle parameters and vibrating conditions, and discussed in five aspects: dynamic equilibrium, separation mode, convection modes, mass distribution and resonance frequency. The results indicate that the upsurge of granular convection and resonance behavior during the processes plays an important role in phase transitions.
Design and Analysis of a Novel Radial Mud Pump Directly Driven by Permanent Magnet Disc Synchronous Motor
Authors: Liang J. T. , Zhao S. D. , Hu Y. H.
Published: August 2012

Mud pump is an important component of drilling equipments, which transports flush fluid like mud or water into bore in order to cool drill and carry debris. In this paper, a novel radial mud pump directly driven by permanent magnet disc synchronous motor (PMDSM) is designed, the influence of different numbers of plunger cylinders on the pump’s flow pulsation is analyzed to determine the pump’s configuration and driving requirement, and the structure and performance parameters of the direct drive PMDSM are calculated by finite element analysis. Compared with conventional mud pumps, the novel pump is characteristic that the structure is simple, working stability and efficiency are greatly improved, also the life of the equipment is extended.
Relay Feedback Oscillator Design for Modeling Circadian Rhythms in Cyanobacteria
Authors: Fiser Jaromir , Zitek Pavel , Cerveny Jan
Published: August 2012

The paper introduces a relay feedback oscillator for modeling circadian rhythms in cyanobacteria. The relay feedback oscillator is equipped with low pass filter F(jω), hysteresis-type relay and negative feedback. This negative feedback represents an autoregulatory mechanism of the circadian clock and the notion of this autoregulatory mechanism is based on the well-known Goodwin biochemical oscillator [1]. The relay is responsible for the mediation of both the activation and degradation of oscillator state variables (protein concentrations) and in this way the pacemaker is constituted. Later on, low pass filter poles are identified for the purpose of modeling auto-oscillations with the free running period of 24h and the method of the pole identification consists in an ultimate frequency test providing stability margin of a single-loop composed of the filter and the relay in the feedback. Next, a relay output / input ratio of amplitudes and hysteresis are found out by the graphical test of the single-loop on the stability margin which is carried out in Bode graph. Finally, the output correspondence of relay feedback oscillator model with Miyoshi oscillator [2] is provided because the Miyoshi oscillator is well recognized among biochemical oscillators for species of cyanobacteria.