bluuebunny/crossref_metadata_2025 huggingface dataset:
Fracture Prediction for Sheet Metals Subjected to Draw-Bending Using Forming Limit Stress Criterion
Authors: Saito Masazumi , Kuwabara Toshihiko
Published: April 2014

Draw-bending is one of the typical deformation modes in sheet metal forming. It causes serious thickness reduction to sheet metals and very often leads to fracture. Therefore, it is crucial to establish a fracture criterion for sheet metals subjected to draw-bending. In this study, a fracture criterion for sheet metals subjected to draw-bending is investigated using the concept of the forming limit stress criterion. The test material used is a dual phase steel sheet (DP590Y) with a thickness of 1.2 mm and a tensile strength of 590 MPa. Draw-bending experiments of a wide specimen are performed using three different die profile radii: 4, 6 and 10 mm. The forming limit stress of the test material under draw-bending, σDB, is precisely determined from the experimentally measured drawing force and the cross sectional area of the specimen, determined from the strain distribution in the vicinity of fracture using a 2 mm square grid. In addition, multiaxial tube expansion tests are performed to measure the forming limit stress under plane strain tension, σPT. It is found that σDB almost coincides with σPT. Thus, it is concluded that σPT can be a fracture criterion for a sheet metal under draw-bending, at least for the high strength steel sheet used in this study.
Application of the Statistical Safety Evaluation Method to the Small Break Loca With High Pressure Injection Failure: Quantification of the Uncertainty of Uncovered Core Heat Transfer Model
Authors: Torige Toshihide , Kinoshita Ikuo
Published: April 2014

In order to improve the reliability of the accident management technique “low-pressure injection by intentional depressurization of steam generator secondary side” in small-break loss-of-coolant accidents (SBLOCAs) with high-pressure injection failure, a statistical safety evaluation method is applied to the thermal-hydraulic analysis of this event. In a past study, the Phenomena Identification and Ranking Table (PIRT) was made and important phenomena were extracted. Then, sensitivity analyses with the important phenomena were carried out, and the influence on peak cladding temperature (PCT) was checked. As a result, one of the parameters whose influence on PCT was especially great was identified as “uncovered core heat transfer”. In this study, the uncertainty of the uncovered core heat transfer model was quantified using separate effect test data. As the separate effect test, uncovered-bundle heat transfer tests done with the Thermal Hydraulic Test Facility (THTF) of Oak Ridge National Laboratory (ORNL) were used. The THTF is a high-pressure bundle thermal-hydraulics loop, and was designed to produce a thermal-hydraulic environment similar to that expected in a SBLOCA.
Experimental Study of Heat Transfer Characteristics of a Bluff Body Interacting With a Rib by Using Liquid Crystal Thermography
Authors: Ghorbani-Tari Zahra , Wang Lei , Sunden Bengt
Published: April 2014

In the present study, the effects of a single rib on the local heat transfer around a bluff body are examined by using the steady state liquid crystal technique. By varying the spacing between the bluff body and the rib, the interaction between the rib and the bluff body can be controlled. The bluff body is oriented vertically towards the flow direction and spans the whole height of the channel. The bluff body has a rectangular cross-section (height b = 80 mm, width 40 mm) while the rib has a square cross-section (rib height e = 10 mm, rib width 10 mm). The rib is placed in the upstream region of the bluff body either by a spacing L = 100 and 50 mm to yield non-dimensional spacing to rib height ratios L/e = 10 and 5 respectively. Here, the re-attachment length (xR) for a single rib is about 7.5e. The values of the Reynolds number based on the channel hydraulic diameter (Dh) are 55,000 and 89,000. The experimental results revealed that the presence of the rib at L/e = 10 has a more pronounced effect on the enhancement of the heat transfer upstream region of the bluff body. The effect of different L/e on the local Nu number distribution in the wake of the bluff body is small.
Modeling the Temperature Distribution in the Contact Area of a Moving Object in the Case of Linear Friction Welding
Authors: Bikmeyev Alexander T. , Gazizov Rafail K. , Vairis Achilles , Yamileva Alfiya M.
Published: April 2014

This paper describes the results of the mathematical and computer modeling efforts of heat generation in the contact area of a moving object on an infinite plane with friction. The distribution of contact pressure with a linear approximation was obtained. The heat equations for a nonlinear volume heat source were solved. It is shown, that at the initial stages of the linear friction welding (LFW) process temperature distribution is non-elliptical with two hot spots appearing near the edges of the moving specimen. Then as the process progresses these two spots expand and move to the center of the specimen. The results of the mathematical and the numerical modeling in ANSYS APDL software are in good quantitative agreement.
Drop-on-Demand: A Scale Analysis
Authors: Delhaye Jean-Marc , Coutris Nicole , Herran Leigh
Published: April 2014

An increasing number of applications deal with dispensing of micro-droplets. For several years the fluids used were mostly Newtonian with low viscosity but there is nowadays a tendency to use more complex fluids. Some recent applications are encountered in the pharmaceutical industry where there is a need of producing on-demand identical droplets of a given size that can be used for drug delivery and in bioengineering where droplets have to contain cells used for tissue manufacturing or organ printing. The objective of the paper is to show that scale analysis is an efficient tool to classify the physical phenomena contributing to the breakup of a jet or of a liquid filament of a complex fluid and to provide guidelines for controlling the droplet formation process.
Precision Measurement and Control of Synchronization Errors in a Contact-Type Printing Machine for Fine Pattern Printing and Overlay Improvement
Authors: Kang Dongwoo , Lee Taik-Min , Choi Youngman , Lee Seung-Hyun , Yoon Dukkyun , Kim Inyoung , Jo Jeongdai
Published: April 2014

Next-generation patterning processes have been extensively studied recently, with a view to replacing the photo-lithographic process and to reducing production costs. For micron scale patterning, the printing process is one of major candidates. In particular, contact printing is more promising in view of the possibilities for mass production. In this process, the motion of the two printing contact surfaces should be synchronized perfectly to prevent slip and unwanted distortion in the surfaces and to make precise ink transfer between the surfaces. In this article, a force-based direct measurement method of the synchronization error is proposed, and the effect of synchronization error on the printing process is analyzed.
Prediction of Space Heating Consumption in District Heated Apartments
Authors: Popescu D. , Ungureanu F.
Published: April 2014

Enhancing energy efficiency from the producer to the end-users is a prioritized objective of European energy policies. The most difficult element to understand and to control is the last link, the consumer.

Most simulation tools for the estimation of heat demand in buildings are based on the input parameters according to environmental conditions and the features of the materials and equipments. Studies have revealed that even if sophisticated programs are used, a gap between calculated and post occupancy space heating consumption rates occurs.

Based on billing history, the present paper proposes a cluster analysis method to identify the grouping trends of habitants’ consumption. For modeling the heat consumption at end-user level and predicting the trends of energy demand, artificial neural networks (ANNs) technique was used. Unlike most prediction methods that have the entire building in view, the proposed technique can be applied to individual apartments situated in condominiums.
CFD Analyses and Design of a Turbocompound System
Authors: Vogel Thomas , Epple Philipp , Hermann Andreas , Willinger Bettina , Delgado Antonio
Published: April 2014

In a turbocompound (TC) system a turbocharged engine is coupled with an additional power turbine, which recovers exergy of the exhaust gas after the turbocharger. The gained power is added to the engine power by a gearbox and a hydrodynamic coupling. The benefit of turbocompound is that the efficiency of internal combustion engines is improved substantially.The challenge with turbocompounding is that a high speed turbine is coupled with a slow speed engine. Through the transient requirements in mobile applications the operating points of the engine are variable while the turbo machine is designed for a continuous and steady flow. Matching the components is an additional challenge in designing the flow path of a TC System. A systematic approach in which the flow path is divided into three regions is applied: the interstage duct, the power turbine consisting of the rotor and its guide vane as well as the exhaust gas collector. After defining performance criteria for the individual regions, they are analysed by computational fluid dynamics (CFD). For this purpose, the model for the CFD-simulation is validated with measurements. For the interstage duct the influence of the mass flow and the outlet swirl of the turbocharger are analysed. For the exhaust gas collector the influence of the outlet swirl and mass flow from the power turbine is evaluated by a sensitivity study. Based on verified CFD simulations as well as analytical considerations it was possible to show that an improvement of the turbine performance is still possible. Parameters to be optimized were identified. As a result of the study an improved method for high efficiency aerodynamic design of turbocompound systems was developed. Based on this method the parts of the TC system were aerodynamically optimized. The performance of the new design was verified by CFD. Improvements in the power output up to 10% were achieved in stationary engine points.
Numerical Study to Analyze the Effects of Hot/Cold Aisle Configurations on Heat Transfer Phenomenon in a Data Center
Authors: Nazir Kamran , Durrani Naveed , Akhtar Imran , Khalid M. Saif Ullah
Published: April 2014

Due to high energy demands of data centers and the energy crisis throughout the world, efficient heat transfer in a data center is an active research area. Until now major emphasis lies upon study of air flow rate and temperature profiles for different rack configurations and tile layouts. In current work, we consider different hot aisle (HA) and cold aisle (CA) configurations to study heat transfer phenomenon inside a data center. In raised floor data centers when rows of racks are parallel to each other, in a conventional cooling system, there are equal number of hot and cold aisles for odd number of rows of racks. For even number of rows of racks, whatever configuration of hot/cold aisles is adopted, number of cold aisles is either one greater or one less than number of hot aisles i.e. two cases are possible case A: n(CA) = n(HA) + 1 and case B: n(CA) = n(HA) − 1 where n(CA), n(HA) denotes number of cold and hot aisles respectively. We perform numerical simulations for two (case1) and four (case 2) racks data center. The assumption of constant pressure below plenum reduces the problem domain to above plenum area only. In order to see which configuration provides higher heat transfer across servers, we measure heat transfer across servers on the basis of temperature differences across racks, and in order to validate them, we find mass flow rates on rack outlet. On the basis of results obtained, we conclude that for even numbered rows of rack data center, using more cold aisles than hot aisles provide higher heat transfer across servers. These results provide guidance on the design and layout of a data center.
Effect of Adhesive Flaws on the Strength of Adhesive Joints
Authors: Hua Yi , Gu Linxia
Published: April 2014

The influence of interior and surface flaws in Z-shaped adhesive joints of carbon/epoxy wind turbine blades is examined using finite element method. Contour integral method is used for evaluating the stress intensity factors at the flaw tips, while the strength of the joint is assessed through the crack initiation and propagation simulation. The effect of adhesive shear modulus has also been investigated.
A Sensitivity-Based Approach to Improve Efficiency of Automotive Chassis Architecture
Authors: Valgimigli Alessandro , Bertocchi Enrico , Lazzarini Alberto , D’agostino Luca , Splendi Luca
Published: April 2014

The strong competition of the automotive market brings the industries to look continuously for more challenging comfort and performance standards.

These requirements often contrast with the need for weight reduction related to the restrictive emissions limits.

In this scenario, the investments aimed at increasing the structure efficiency (stiffness-to-weight ratio) become fundamental.

The objective of this work is to propose a methodology that allows to identify the most important chassis areas in terms of efficiency: the design and research efforts could then be focused on the real determinant parts. This is done through a sensitivity process that works on frame subsystems and then on each component, first varying the material properties and then the thickness (and so the mass). The designing loadcases considered are the torsional stiffness, bending stiffness, modal analysis and frequency response analysis.

The results show which are the most important subsystems and components that affects the chassis efficiency and that will have to be re-designed in order to improve the current architecture.
Comparison of Muffler Performance Criteria Using Finite Element Analysis and Field Measurements
Authors: Mang Scott , Vipperman Jeffrey S.
Published: April 2014

The assumption of one dimensional acoustic propagation breaks down at very low frequencies for large sized mufflers. Finite element analysis is the preferred method for predicting the performance of mufflers when three dimensional acoustics are present. In this study three performance metrics were measured in field tests, and then the results of the FEA simulations were compared to the field measurements. There were three muffler models considered in this study. For the purpose of protecting intellectual property they will be referred to as muffler models A, B, and C. A is the smallest muffler model, C is the largest, and B is the mid-size model.

Good agreement is found between the field measurements and the FEA simulations. A method for increasing the accuracy of noise reduction and insertion loss predictions for realistic environments is also presented.
3 Dimensional Characterizations of the Impact Damaged Fiber Reinforced Composites
Authors: Salagame Raghavendra , Patlolla Vamsidhar , Asmatulu Ramazan
Published: April 2014

Impact damages on the composites need to be understood thoroughly for the designing, manufacturing and repairing of the aircraft composite parts. Larger diameter of the impactor can create a shallow dent on the outside, but a significant damage on the inside of the composites. Larger impact dents can be easily detected during the regular visual inspection, while the smaller dents with significant internal damages cannot be detected which may compromise the structure resulting in safety concerns for the composite aircraft. 3D characterization of impact damages on glass, carbon, and Kevlar fibers reinforced composite structures may be necessary to better understand the material behavior and provide better designs. In the present study, Kevlar fiber composite panels were prepared using a wet layup in a vacuum curing oven while the glass and carbon weave material composite panels were fabricated using pre-preg and cured in the autoclave. These composite panels were impacted with 3 different tup diameters and 2 different energy levels. Impact load was measured using a load cell and the velocity was detected using a velocity detector. The impacted composite panels were then subjected to the non-destructive inspection (NDI) tests, and their 3D structural damages were evaluated in detail. The test results showed that the shallow dent impacts created significantly deeper and bigger internal damages on the structure of the composites. In addition to that, the impact damages on the composites were dependent on the composite types and structures, which may be critical for the design, manufacture and repair of different aircraft composites.
Segregated Parallel Computing for Isoelectric Focusing of Proteins
Authors: Yoo Kisoo , Liu Jin , Dutta Prashanta
Published: April 2014

A parallel algorithm is introduced to simulate isoelectric focusing (IEF) in a microfluidic device. This new algorithm is based on segregated method for solving a large number of mass conservation equations in the system. An in house numerical code is developed to simulate the transient focusing behavior of cardiac troponin I (cTnI) protein in a pH field formed by ampholytes in presence of an applied electric field. The effectiveness of the parallel scheme is assessed by analyzing the CPU times for each process. Numerical results show that the electric potential distribution is nearly independent of time or concentration of amphoteric molecules. Thus, the charge conservation equation is not solved after the first time step to reduce the computational expenses. As expected, the solution of mass conservation equations for ampholytes is the computational hot spot, and solving them in parallel reduces the overall computing time. The proposed algorithm is very suitable for solving mass conservation equations of 100∼1000 components used to form continuous pH in IEF.
Indenter Tip Dependence in the Determination of Elastic Modulus in Polymers
Authors: Sanei Seyed Hamid Reza , Alisafaei F. , Han Chung-Souk
Published: April 2014

The two most common outputs of nanoindentation experiment are hardness and elastic modulus. Length scale dependent deformation in polymers has however been observed in different experiments such as microbeam bending, torsional thin wires and indentation testing which may affect the mechanical testing. Unlike in metals where the size dependency is attributed to necessary geometry dislocations, the origin of length scale dependent deformation in polymers is not well understood. In this study, elastic modulus of polydimethylsiloxane (PDMS) is determined using both Berkovich and spherical tips. Observing different trends for elastic modulus upon the change of indentation depth using these two different tips brings up the question which tip should be used to get the real mechanical properties of PDMS which is discussed here. Surface roughness, surface effects and the imperfection of the Berkovich indenter tip are negligible at the studied length scale.
The University of Tennessee EcoCAR 2 Communications, Outreach, Education and STEM Recruiting Program Overview: Year 2
Authors: Routh Katelynn M. , Curran Scott J. , Irick David K.
Published: April 2014

The U.S. Department of Energy’s (DOE) Advanced Vehicle Technology Competition (AVTC) series is a long running collegiate vehicle design competition for North American universities. The current three year competition series, known as EcoCAR 2: Plugging In To the Future, has students design and build a hybrid electric vehicle (HEV) that also incorporates alternative fuel. Teams are donated a 2013 Chevrolet Malibu by General Motors to modify. A significant aspect of the competition series is the public outreach and education aspect that leverages the expertise of the students in advanced vehicle technologies and alternative fuels. This also highlights the systems level approach to integrating all aspects of the vehicle to build a vehicle that has the best possible fuel economy, lowest well-to-wheel greenhouse gas emissions and lowest criteria air pollutant emissions while maintaining or exceeding vehicle performance, utility and safety. This paper presents an overview of the University of Tennessee’s (Team Tennessee) EcoCAR 2 outreach program, including core program goals and measures of effectiveness of the program for Year 2 of the competition. The paper focuses on the role that such programs can have on effective science, technology, engineering and mathematics recruiting through an overview of the outreach activities and the integration of hands on activities and partnerships with local schools. The leveraging of outreach and education capabilities with the team’s outreach partners is also highlighted.
Computer Modeling and Simulation Framework for Particulate Spray Based Manufacturing Processes
Authors: Mukherjee Debanjan , Zohdi Tarek
Published: April 2014

Particulate media are ubiquitous in modern manufacturing processes. These include spray-forming, abrasive finishing, and sintering based processes amongst others. All of these processes involve a flowing stream of discrete, particulate media. For these processes, the aggregate behavior originating from the individual particle or grain dynamics is of critical importance from a process engineering perspective. The discrete nature of the media poses unique challenges in formulating direct continuum theories. This motivates investigating appropriate discrete computational techniques. In this paper, we present a computer simulation framework based on collision driven particle dynamics to investigate the engineering of such manufacturing processes. This is part of an ongoing work on developing a general-purpose computer simulation tool to analyze the dynamics of particulate and granular media in engineering applications. This paper presents the overall framework and the underlying physical models. In particular, our focus is on modeling individual particle-based phenomena (including collisions, heat-exchange, and energy loss) and deriving the aggregate response of the media from individual particle dynamics. The technique is demonstrated using a numerical example for a spray coating deposition process. This example tracks the particulate behavior from the nozzle opening downstream until impact with substrate. Such investigations are useful to understand the effect of process parameters on the engineered output — which in this case entails the properties of the surface coating. The simulation is found to be reasonable in performance time.
Development of a Methodology for the Evaluation of Motion Sickness Incidence in Railways
Authors: Braccesi Claudio , Cianetti Filippo , Scaletta Renzo
Published: April 2014

The present paper illustrates an evaluation method developed by the authors to quantify the index of motion sickness incidence (MSI) in railways motion conditions. This index is formerly defined in literature to quantify diseases coming from low frequency motions (kinetosis). The proposed method, suggested as alternative to the only one existing in reference norm, involves PCT index, well known in railways context, and weighting curves for accelerometric signals, which are also specified in railways regulations. The approach of the method, consistent with the theoretical model, developed by the authors themselves in previous works, allows to obtain MSI index versus time and/or track progressive distance. The model is validated through comparison with experimental data available in literature and with measures recorded and obtained on regular trains during tests performed in Slovenia (EU).
Optimization of CHCP Operation Strategy: Cost vs Primary Energy Consumption Minimization
Authors: Facci Andrea Luigi , Andreassi Luca , Martini Fabrizio , Ubertini Stefano
Published: April 2014

An effective methodology to determine the optimal operational strategy for a complex CHCP plant is presented. The model is based on the minimization of a chosen variable and it is organically developed integrating thermodynamics and economics. The graph-based optimization algorithm is developed in order to find the optimal set-points of the energy system components in a sufficiently short-time. By this way the model is applicable to real industrial problems, especially when the energy is sold to the electricity market. The problem in study is discretized in time and plant states, represented as weighted graph, and the strategy that minimizes the total cost is determined using backward dynamic programming. The proposed methodology has been applied to the optimization of the set-point of an internal combustion engine based plant used to satisfy an hospital energy load, under different seasonal load conditions (winter, summer and transitional seasons) and energy prices. Two different optimization criteria are considered, namely economical optimization and primary energy consumption minimization. It is then demonstrated that the model can be effectively applied to analyze the cost and profit in energy conversion in power plants, related to electricity price, fuel price, running of turbine and auxiliary equipment, service power consumption. In particular, the chosen test case demonstrates not only the model reliability but also the economical and thermodynamic convenience of using the model itself to optimize the plant.
Regimes Map and Transition Boundaries for Immiscible Liquids Flow in Co-Axial Microtubes
Authors: Yang In-Hwan , El-Genk Mohamed S.
Published: April 2014

This work numerically simulates immiscible liquids flow in co-axial microtubes and investigates the effects of changing the injection velocities and physical properties of the liquids and the diameters of the co-axial microtubes on the prevailing flow regimes for forming disperse droplets. These regimes are dripping, transition and jetting. The solution is validated by comparing the present results with those of reported numerical and experimental investigations in all three flow regimes. The generated motion picture movies of the computation domain for up to 18 cycles of forming disperse droplets, help determine not only the breakup mechanisms of the droplets but also the conditions for shifting among the three regimes. A dimensionless correlation is developed based on the present numerical results for predicting the boundary between the transition and the jetting regimes. The correlation is good agreement, to within ±10%, with numerical results and within 20% of the reported experimental measurements for ionized water and PDMS (Polydimethylsiloxane) mineral oil. A flow regime map of the dripping, transition and jetting regimes and of the condition for shifting among them is developed.
Bubble Formation and Coalescence Under the Influence of Electric Fields
Authors: Herman Cila
Published: April 2014

The high heat transfer rates associated with phase-change processes, such as boiling, make them an attractive solution in a range of industrial operations. In terrestrial conditions, the buoyancy force is responsible for bubble removal from the surface, which is essential for heat removal from the surface. Since in space the gravity level is orders of magnitude smaller than on earth, bubbles formed during boiling remain attached at the surface and they also show a tendency to coalesce. As a result, the amount of heat removed from the heated surface is different from terrestrial conditions and it can decrease considerably.
Improvement in Precision, Accuracy, and Efficiency in Standardizing the Characterization of Granular Materials
Authors: Tucker J. R. , Shadle L. J. , Benyahia S. , Mei J. , Guenther C. , Koepke M. E.
Published: April 2014

Useful prediction of the kinematics, dynamics, and chemistry of a system relies on precision and accuracy in the quantification of component properties, operating mechanisms, and collected data. In an attempt to emphasize, rather than gloss over, the benefit of proper characterization to fundamental investigations of multiphase systems incorporating solid particles, a set of procedures were developed and implemented for the purpose of providing a revised methodology having the desirable attributes of reduced uncertainty, expanded relevance and detail, and higher throughput. Better, faster, cheaper characterization of multiphase systems result.

Methodologies are presented to characterize particle size, shape, size distribution, density (particle, skeletal and bulk), minimum fluidization velocity, void fraction, particle porosity, and assignment within the Geldart Classification. A novel form of the Ergun equation was used to determine the bulk void fractions and particle density. Accuracy of properties-characterization methodology was validated on materials of known properties prior to testing materials of unknown properties. Several of the standard present-day techniques were scrutinized and improved upon where appropriate. Validity, accuracy, and repeatability were assessed for the procedures presented and deemed higher than present-day techniques.

A database of over seventy materials has been developed to assist in model validation efforts and future designs.
Utility of Matrix Algebra and Graphical User Interface in Design of Six-Bar Mechanism for Rectilinear Motion Generation
Authors: Fallahi Behrooz , Seyyed Mousavi Seyyed Alireza , Perla Arjun Kumar , Mokhtarian Ilia
Published: April 2014

Many applications require design of a linkage that executes a rectilinear motion. In this study a synthesis procedure for six-bar mechanism for generation of rectilinear motion is presented. To achieve this goal, matrix algebra is used to describe translation, rotation, and inversion of motion of links. These concepts then are used to implement the classical three-precision point synthesize of a four-bar mechanism with a coupler point that traces a straight line. The motion of this four-bar mechanism is inverted and then is used to synthesize a second four-bar mechanism. The merging of these two four-bar mechanisms forms a six-bar mechanism such that the motion of one link is rectilinear motion. To implement this procedure, a graphical user interface is developed for the ease of exploring the design space. The utility of this approach is demonstrated by designing a linkage for a lift-truck.
Evaluation of Fluid Behaviour and Mixing Efficiency in Predefined Serpentine Micro-Fracture System
Authors: Pawar Gorakh , Miskovic Ilija , Basavarajappa Manjunath
Published: April 2014

Scientific research and development in the field of microfluidics and nanofluidics technology has witnessed a rapid expansion in recent years. Microfluidic and nanofluidic systems are finding increasing application in wide spectrum of biomedical and engineering fields, including oil and gas technology. Fluid flow characterization in porous geologic media is an important factor for predicting and improving oil and gas recovery. By developing understanding about the propagation of hydraulic fracturing fluid constituents in irregular micro- and nano-structures, and their multiphase interaction with reservoir fluids (e.g. mixing of supercritical CO2 with oil or gas) we can significantly improve efficiency of the current oil and gas (O&G) extraction process and reduce associated environmental impacts. In present paper, mixing of hydraulic fracturing fluid constituents in three dimensional serpentine microchannel system is simulated in CFD environment and results are used to evaluate mixing efficiency for different fracturing fluid compositions. In addition, pressure drop along the length of serpentine micro-channel is evaluated. Serpentine micro-channels considered in this study consist of periodic symmetrical and asymmetrical proppant particles, placed on both sides of the channel over the full length of the channel, to simulate realistic geometrical constraints usually seen in geological fractures. The fluid flow is characterized as a function of the proppant particle radius by varying size of adjacent proppant particles. Further, the flow is characterized by varying distance between adjacent proppant particles. Overall, this study will be primarily helpful to gain fundamental understanding of fracturing fluid mixing in micro-fractures, similar to real geologic media. In addition, this study will provide an insight into variations of fracturing fluid mixing efficiency, and pressure drop in micro-fracture systems as a function of geometry of the proppant particles at different flow rates.
Combustion Simulation of Hydrogen-Fuelled Diesel Engines Using Detailed Chemical Kinetics
Authors: Khairallah H. A. , Koylu U. O.
Published: April 2014

During the past decade, considerable effort has been made to introduce alternative energy sources for use in conventional diesel and gasoline engines. Many researchers have attempted to use hydrogen as a fuel in the diesel engine due to its ability to reduce pollutant emissions, such as carbon monoxide and unburned hydrocarbons. With the rapid increase in computational capabilities, 3D computational fluid dynamics CFD codes become essential tools for practical design, control and optimization of hydrogen engines. In the present study, detailed chemical kinetic reactions with twenty steps of hydrogen oxidation with additional nitrogen oxidation reactions were coupled with AVL FIRE® code to study combustion processes in a diesel engine using hydrogen as the fuel. Moreover, a spark ignition model built by C++ program was incorporated into the AVL FIRE® software to simulate the hydrogen ignition behavior. The model was validated by the experimental results and employed to examine important parameters that have significant effects on the engine performance. The simulation results show that the variations of peak in-cylinder pressure, heat release rate, gas cylinder temperature, ignition delay, combustion duration, and NO emissions reasonably agree with the experimental findings. The exhaust gas recirculation (EGR) was also employed at different levels in the engine model. It was found that both peak cylinder pressure and gas cylinder temperature decrease as EGR level increases due to dilution effect. The computations are consistent with the hypothesis that gas cylinder temperature decreases with increasing EGR level and that the decrease in gas cylinder temperature results in the reduction in NO emissions.
Framework for Management of Internet Objects in Their Relation With Human Sensations and Emotions
Authors: Luís-Ferreira Fernando , Marques-Lucena Catarina , Sarraipa João , Jardim-Goncalves Ricardo
Published: April 2014

Emotions are what make us human and emotions are what make us different. A person can make a list of such expressions about the role of human emotions, as they play a central role in our lives, in our interactions with others and the surrounding environment. Emotions are in a broad sense the regulators of our interaction with the world as they play a central role in our perception of the world and in our knowledge construction.

In another angle, sensations are our immediate detector of the surrounding environment as, since ever, we see, touch and smell what is around us, we ear friendly voices or run from predator’s sounds and taste food that keep us alive. Both emotions and sensations can be used to describe our living and our main interactions with the world.

However, despite that important role of senses and emotions, there is a poor representation of sensorial information and lack of understanding of emotions from the side of computational systems. Subsequently it is noticeable the absence of support to acquire and fully represent human sensorial experience and lack of ability to represent, and appropriately react, from those systems to emotional activity. The proposed work consists in developing a framework that acquires knowledge about human emotions from self-reporting or the interaction with Internet objects and media. In particular, it intends to facilitate their emotions description at the Internet from proposed samples of sensorial information allowing a later management of that knowledge for the most diverse objectives, as an example, for searching objects or media through similarities of emotional and sensorial patterns.
Analytic Model Able to Assist in Parametric Design of Cycloidal Rotor Thrusters
Authors: Leger Jakson A. , Páscoa José C. , Xisto Carlos M.
Published: April 2014

In this work we present in a unified way an analytic parametric design method for cycloidal rotors. The method allows for a fast identification of thrust, lift and power parameters as a function of the rotor geometries. Even if, in recent years, the CFD based approaches have been able to provide adequate means to analyse this class of flow, the present model is useful to provide immediate guidelines in the preliminary stages of design, and also to be used as a tool to perform optimization of the cyclorotor. The cycloidal propeller, which can be described as a horizontal rotary wing, offers powerful thrust levels, and a unique ability to change the direction of that thrust almost instantly. The cycloidal propeller is the most efficient form of propeller conceived to date, and was recognized as the solution to overcome propulsion deficiencies associated with airships and other special air vehicles. Several test cases are presented, for three different working regimes, showing the versatility of the developed analysis tool.
A Milli-Fluidic Device for Electrical Impedance Spectroscopy of Complex Liquids
Authors: Shahidi Seyedehsan , Koch Charles R. , Bhattacharjee Subir
Published: April 2014

Rapid characterization of complex liquids such as solutions, mixtures, dispersions, and emulsions is useful in a variety of industrial applications ranging from cosmetics, pharmaceuticals, to petroleum production. An electrical impedance spectroscopy (EIS) based technique for rapidly determining the characteristics of liquid-liquid mixtures is presented in this study. A milli-fluidic liquid film impedance measurement cell is developed employing 3D printing technology. The cell is tested using glycerol-water mixtures followed by castor oil in water emulsion samples. Frequency response analysis and equivalent circuit modeling are performed on each sample to quantify the emulsion properties in the form of equivalent capacitance and resistance. The developed technique provides an inexpensive and disposable, yet robust experimental platform for applying EIS to investigation and rapid estimation of different properties of oil-water emulsions.
Three-Dimensional Fluid-Structure-Interaction Simulation of Tilting Disk Mechanical Heart Valve
Authors: Aliabadi Ardavan , Hoffmann Klaus A.
Published: April 2014

The current computational effort will focus on the numerical analysis of current tiling disk MHVs. In this work an implicit fluid-structure-interaction (FSI) simulation of the Bjork-Shiley design was carried out using in-house codes implemented in the commercial code software FLUENT™. In-house codes in the form of journal files, schemes, and user-defined functions (UDFs) were integrated to automate the inner iterations and enable communication between the fluid and the moving disk at the interfaces. Based on the investigations of the current simulations, a new design aiming at improving the hemodynamic performance is suggested. Hemodynamics of the flow in current tilting-disk valves is compared with the suggested design and it is concluded that the suggested design has a better hemodynamic performance in terms of shear stress values and residence times.
Performance Analysis of a 40mw Class Advanced Humid Air Turbine Pilot Plant
Authors: Watanabe Yutaka , Takahashi Toru
Published: April 2014

Recently, high efficiency and operational flexibility are required for thermal power plants to reduce CO2 emissions and to introduce renewable energy sources. We study the advanced humid air turbine (AHAT) system, which appears to be high suitable for practical use because its configuration is simpler than that of gas turbine combined cycle power plants (GTCCs). Moreover, the thermal efficiency of AHAT system for small and medium-size gas turbines is higher than that of GTCCs.

To verify feasibility of this system and the cycle performance of AHAT system, a 3MW-class pilot plant was built in 2006 by Hitachi, Ltd., which mainly consists of a gas turbine, a water atomization cooling (WAC) system, a recuperator, a humidification tower and a water recovery tower. Through the operational test from 2006 to 2010, we confirmed the feasibility of the AHAT as a power-generation system, and various characteristics such as the effect of changes in ambient temperature, part-load characteristics, and start-up characteristics.

Next step, a 40MW-class pilot plant was built in 2011 and started operational tests. This system mainly consists of a dual-shaft heavy duty gas turbine, a WAC system, a recuperator and a humidifier. As a result of the operational test, it has been confirmed that the pilot plant output achieved rated power output. In this paper, we show the 40MW-class pilot plant running test results, and evaluate thermal characteristics of this plant and the effect of WAC and humidification on performance of this gas turbine system.
Analysis of Entrainment at the Turbulent/Non-Turbulent Interface of a Square Jet
Authors: Ghasemi Abbas , Roussinova Vesselina , Barron Ronald , Balachandar Ram
Published: April 2014

Particle image velocimetry measurements are carried out to study the entrainment at the interface between the non-turbulent and turbulent regions in a square jet. Jet Reynolds number based on the hydraulic diameter of the jet is 50,000. Measurements cover up to 25 diameters downstream of the nozzle exit using five horizontal field-of-views in the central plane of the jet. The turbulent/non-turbulent interface is identified using a velocity criterion and a suitable thresholding method. Using vorticity and swirling strength it is shown that the turbulent/non-turbulent interface separates the rotational and irrotational regions of the flow. Instantaneous velocity vector field superimposed with the turbulent/non-turbulent interface are presented. The relation between the vortex cores in the vicinity of the turbulent/non-turbulent interface and the contractions and expansions noticed in the jet velocity field are explained. Entrainment into the jet is evaluated at each axial distance by identifying the points falling inside the turbulent region of the jet. Compared to a round jet, the square jet entrains more ambient fluid. In addition, normal volume fluxes going through the turbulent/non-turbulent interface of the square jet are found to be larger compared to that of a round jet.
Flame-Made Catalyst for Bio-Methanol Steam Reforming
Authors: Hotz Nico
Published: April 2014

In the present study, a catalyst produced by flame spray pyrolysis (FSP) was evaluated for its ability to produce hydrogen-rich gas mixtures. Catalyst particles fabricated by a novel flame spray pyrolysis method resulting in a highly active catalyst with high surface-to-volume ratio were compared to a commercially produced catalyst (BASF F3-01). Both catalysts consisted of CuO/ZnO/Al2O3 of identical composition (CuO 40wt%, ZnO 40wt%, Al2O3 20wt%). Reaction temperatures between 220 and 295 °C, methanol-water inlet flow rates between 2 and 50 μl/min, and reactor masses between 25 and 100 mg were tested for their effect on methanol conversion and the production of undesired carbon monoxide. 100% methanol conversion can be easily achieved within the operational conditions mentioned for this flame-made catalyst — at reactor temperatures of 255 °C (achievable with non-concentrating solar collectors) more than 80% methanol conversion can be reached for methanol-water inlet flow rates as high as 10 μl/min. The FSP catalyst demonstrates similar catalytic abilities as the BASF, produces a consistent gas composition and produces lower overall CO production. Furthermore, the FSP catalyst demonstrates a better suitability to fuel cell use through its higher resistance to degradation and smaller production of carbon monoxide over long-term use.

In the present study, the merits of using flame spray pyrolysis to produce CuO/ZnO/Al2O3 methanol steam reforming catalysts are examined, and directly compared to catalysts that are commercially produced in bulk pellet form, and then ground and sieved. The comparison is performed from several different perspectives: catalytic activity and CO production at various temperatures and fuel inlet flow rates; surface and structure characteristics are determined via scanning electron and transmission electron microscopy; surface area characteristics are determined via Brunauer-Emmett-Teller (BET) tests.
Design of a Data Acquisition System for Temperatures Monitoring in Thermal Envelope and Water Consumption in Housing
Authors: Bonilla García Diego Ramón , Lambert Arista Alejandro Adolfo , Vega Castellanos Ramsés
Published: April 2014

This work describes the design, construction and test of a data acquisition system which performs the real-time monitoring and recording of temperatures in thermal envelope and water consumption in households. This system allows diagnosis and assessment of efficient use of water and a thermal report for electric efficiency purposes. The prototype was subjected to comparative tests with commercial instruments that were used during the project of collaboration with Universidad Autonoma of Baja California and Dennis engineering. The project was developed for energy-efficient housing prototypes for the middle market residential of Mexicali, localized at the state of Baja California in Mexico. At first case, a high gain or loss of heat causes significant increases of important loads as the refrigerator and air conditioning owing to their increment in operation times. Many efficiency energy projects make use of traditional systems for temperature monitoring, whose characteristics exceed the requirements for this type of application and they present economic disadvantages, which can be solved with virtual acquisition systems. Two virtual instruments in LabVIEW were developed which allow real-time acquisition, analysis and recording, with flexible viewing by the user of temperatures and volume of water consumed. Also automatically save data in excel files by specific times. This system can diminish the cost of a conventional temperature monitoring system with 8 acquisition channels approximately in a 50%, keeping precision and accuracy required for this type of applications. The dispositive has the flexibility for monitoring other variables for energy audit, and currently is being tested for climate and electric power parameters.
Sub-Diffraction Limit Three Dimensional Particle Tracking Velocimetry
Authors: Snoeyink Craig A. , Christopher Gordon , Barman Sourav , Wereley Steve
Published: April 2014

Here we present an optical measurement technique and image analysis process capable of tracking particles in three dimensions with a single point of view. In addition to single view 3D-PTV, the optical system is capable of tracking individual particles even at particle-particle spacings that are closer then the diffraction limit of the base imaging system.

The measurement system, termed Bessel Beam Microscopy (BBM), functions as an attachment for a microscope that fits between the microscope base and camera. The addition of the BBM attachment transforms the point spread function (PSF) of the microscope allowing two unique functions: single image superresolution imaging, and the extraction of three dimension location information of particles without calibration.

The result is a fluid characterization tool with unique capabilities for velocimetry and characterization of the dynamics of dense fluid-particle suspensions.