bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Number of Blades on the Performance of Helical-Savonius Vertical-Axis Wind Turbines
Authors: Rashidi Majid , Kadambi Jaikrishnan R. , Ebiana Asuquo , Ameri Ali , Reeher James
Published: October 2013

This work presents the results of a series of experiments conducted on three different scaled-down Helical-Savonius vertical axis wind turbines (VAWT) systems. The work was aimed at investigating how the number of blades may affect the performance of the Helical-Savonius VAWTs. The first turbine consisted of two helical blades, the second turbine had three blades, and the third turbines had four blades. The work included a design phase in which the three dimensional (3D) geometry of each of three VAWTs were developed using a 3D drawing software. The 3D models were then uploaded to a rapid-prototyping machine to fabricate the VAWTs. The projected areas of each of the VAWTs were that of a rectangle of 4″ × 6″. A test setup was designed and developed to examine the performance of the scaled-down turbines. A 1.1 KW floor fan was used to simulate wind flow in the laboratory for testing of the turbines. A flow straightener was also designed and developed in order to minimize the turbulent flow of the air at the discharge opening of the floor fan. The test results show that the 3-bladed rotor design performs better than the two and four bladed turbines. Under the same wind speed conditions the 3-bladed turbine produced 18% more power compared to the 2-bladed turbine, whereas the 3-bladed turbine produced 30% more power compared to the 4-bladed turbine.
Study on the Flange Manufacturing of Pipe With High Pressures
Authors: Baek SeungGul , Song XueGuan , Park YoungChul , Kim TaeGual , Park KyoungYong , Kim KwangSun
Published: October 2013

Pipe flanges are usually welded or screwed to the pipe end and are connected with bolts. This approach is very simple and widely used for a long time, however, it results in high development cost and low productivity and some safety problems at the welding area. In this research, a new approach of forming pipe flange based on cold forging and floating die concept is presented. This innovative approach increases the effectiveness of the material usage and save the time cost compared with conventional welding method.

To ensure the dimensional accuracy of the final product, finite element analysis are carried out to simulate the process of cold forging, and orthogonal experiments method are used to investigate the influence of four manufacturing factors and predict the best combination of them. In addition, a real product is manufactured in terms of the best factors predicted by FEA and optimization method to validate the proposed approach. The experimental results show that the approach is effective for the forming of pipe flange, and can be widely used later.
Damage and Crack Analysis in a Li-Ion Battery Electrode Using Random Spring Model
Authors: Barai Pallab , Simunovic Srdjan , Mukherjee Partha P.
Published: October 2013

Lithium-ion batteries (LiB) are widely used in the electronics industry (such as, cell phones and laptop computers) because of their very high energy density, which reduced the size and weight of the battery significantly. LiB also serves as a renewable energy source for the transportation industry (see Ref. [1,2]). Graphite and LiCoO2 are most frequently used as anode and cathode material inside LiB (see Ref. [2,3]). During the charging and discharging process, intercalation and de-intercalation of Li occur inside the LiB electrodes. Non-uniform distributions of Li induce stress inside the electrodes, also known as diffusion induced stress (DIS). Very high charge or discharge rate can lead to generation of significant amount of tensile or compressive stress inside the electrodes, which can cause damage initiation and accumulation (see Ref. [4]). Propagation of these micro-cracks can cause fracture in the electrode material, which impacts the solid electrolyte interface (SEI) (see Ref. [2,3,5]). Concurrent to the reduction of cyclable Li, resistance between the electrode and electrolyte also increases, which affects the performance and durability of the electrode and has a detrimental consequence on the LiB life (see Ref. [6]).
Pressure Fluctuation Analysis in Gas-Solid Fluidized Beds Using CFD Simulations
Authors: Deza Mirka , Battaglia Francine
Published: October 2013

Reliable computational methods provide valuable insight into gas-solid flow processes and can be used as a design tool. Of particular interest is the hydrodynamics of a binary mixture of sand-biomass in a fluidized bed. Our study interprets the hydrodynamic states of a fluidized bed by analyzing the local pressure fluctuations of beds of sand and a mixture of cotton stalks and sand over long time periods. Standard deviation of pressure drop will determine different fluidization regimes at inlet gas velocities ranging from 2 to 9 times the minimum fluidization velocity. Bode plots will present the pressure spectra and reveal characteristic frequencies that describe the bed hydrodynamics for different fluidization regimes. This works contribution will present CFD as a useful tool to perform pressure fluctuation analysis, the study of pressure fluctuations in the turbulent regime and the analysis of a binary mixture using CFD.
Implementing a Cohesive Zone Interface in a Diamond-Coated Tool for 2D Cutting Simulations
Authors: Qin Feng , Shen Ninggang , Chou Kevin
Published: October 2013

Coating-substrate interface properties and deposition residual stresses may have significant effects on diamond-coated tool performance. However, it is still distant to understand how the interface mechanical behavior and deposition residual stress together influence the diamond-coated tool thermo-mechanical behavior during machining. In this study, a 2D cutting simulation incorporating deposition residual stresses and an interface cohesive zone model has been developed to demonstrate the feasibility of evaluating coating delamination of a diamond-coated tool during cutting.

It has been shown that even the residual deposition stresses alone may result in crack initiations in the cohesive zone (i.e., the interface). In addition, the study further demonstrates that the feasibility of implementing cohesive zone interface in a diamond-coated tool in 2D cutting simulation. An example of cohesive failure occurred in the cutting simulation is shown. The result shows a large uncut chip thickness can cause cohesive delamination during cutting.
Dynamic Response of RC Structures Subjected to Blast Wave Shock Loading
Authors: Rabie Oruba , Al-Smadi Yahia M.
Published: October 2013

The collapse of significant structures caused by terrorist attacks in the past decades has motivated engineers to study the stability of current structural systems and their susceptibility to collapse. This collapse usually occurs due to blast waves generated by the high explosive bursts in the air that hit the structural components of the buildings leading to catastrophic damages which unfortunately happen before the evacuation. In an effort to find a safety criterion for buildings subjected to blasting; this study uses the nonlinear FEA explicit software LS-DYNA to highlight the effect of blast wave propagation on reinforced concrete column taking into account the standoff distance and charge weight variations. The effects of these two variables have been quantified through the comparison of resulted pressures, displacement and impulses.
Development Drug Delivery Systems by Shock Waves Using Special Microcapsules Including a Gas Bubble
Authors: Tamagawa Masaaki
Published: October 2013

This paper describes development of microcapsule using underwater shock waves, especially (1) making polymer microcapsules including a bubble and analysis of a bubble deformation process in a polymer capsule by pressure wave, (2) making liposome microcapsules with different elastic membrane and disintegration tests by ultrasonic waves.
Investigation of a Seat With an Active Control System for Reducing Vibrations From the Seat, Steering Wheel, and Pedals to the Human Body in a Vehicle
Authors: Ota S. , Nishiyama S. , Nakamori T.
Published: October 2013

This paper describes an active control system aimed at minimizing vertical vibrations from the seat to the human body in a vehicle. This system controls mechanical properties such as spring constants and damping coefficients on the basis of vibration analysis. In our previous study, this active control system could not be validated for a model that considers the steering wheel. This study aimed to clarify the relationship between the mechanical properties of the seat and the vibrations of the human body in a seat–steering wheel–occupant system. Then, a vibration model for such a system was designed and the influence of seat cushions on the vibrations of the human body was examined using this system. The mechanical properties of the bearing surface and the back of the seal were controlled with reference to 1/5–5 times the standard condition, and the influence of seat cushions on the vibrations of the human body was examined by using this system. From these results, the effectiveness of the vibration model and the analytical system was examined by comparing the frequency response results of the analysis and an experiment. It was clarified that the frequency of the first resonance point changed significantly when the mechanical properties of the seat-bearing surface were modified, and the frequency of the second resonance point changed significantly when the mechanical properties of the seat back were modified.
Application of Binary Fluid Ejector in Thermal Vapor Compression Distillation Systems
Authors: Shahamiri S. Ali , Salek M. Mehdi , May Wayne , Martinuzzi Robert J.
Published: October 2013

Ejector Refrigeration Systems (ERS) offer the use of low grade energy sources. These systems are simple in principle; however, suffer from relatively low COP, mainly due to inefficient energy exchange between the primary and secondary fluid flows in the ejector. The use of two chemically distinct fluids in forward and reversed Rankine cycles of such systems has been shown to improve COP. These systems are known as Binary Fluid ERS (BFERS).

This paper focuses on the application of BFERS for the purpose of water distillation. First, a model for an ideal ejector was developed and the maximum theoretical COP of the system was determined. Actual COP of the system was also estimated by computing the entrainment ratio in the ejector using computational fluid dynamic modeling (CFD). The effects of certain fluid properties such as molecular masse and specific heat ratio of the two fluids were investigated with respect to mass entrainment ratio. A number of guidelines for the selection of suitable primary and secondary fluids were developed based on research literature and the potential for increasing COP through the use of chemically distinct fluids, i.e. binary operating fluids.
Nonlinear FEA Simulation of Thorax Dynamic Response Under Blast Load
Authors: Al-Smadi Yahia M. , Sumrein Nedal , Awad Omar , Rabie Oruba
Published: October 2013

Blast overpressure can cause severe injuries of several organs ranging from local injury to collapse or rapture of vital organs rapidly and death. This paper will investigate the thorax dynamic response for blast loading. The presented numerical blast tests will accompany the introduction of new material modeling details. Reliable and robust analysis explicit finite element analysis software (ANSYS and LS-DYNA) will be used to complete 3D finite element model and conduct numerical testing.
Experimental and Numerical Analysis of Membrane-Patterned Meta-Materials
Authors: Ayorinde Emmanuel , Al-Zubi Mohammad , Dundar Akif , Witus Gary
Published: October 2013

Meta-materials show unconventional properties by virtue of their construction which normally includes physically-periodic formations. Various responses of these materials manifest frequency-dependent occurrences of significantly-enhanced and significantly-attenuated values, thus facilitating a wealth of design possibilities. The analysis of these structures presents non-trivial challenges, hence only very simple types are presently under analytical study. In this paper, a formation which includes patterned membrane fillings is explored experimentally and numerically to see if and how well such a construction may be utilized for meta-material applications.
Measurement of In-Plane Thermal Conductivity Using Suspended SiNx Islands
Authors: Alaie Seyedhamidreza , Goettler Drew F. , Abbas Khawar , El-Kady Ihab , Leseman Zayd C.
Published: October 2013

In order to measure in-plane thermal conductivity, electrical resistivity, and Seebeck Coefficient of Phononic Crystals (PnCs) a micro device is designed and fabricated to host different nano-scale samples. The device is comprised of two SiNx suspended membranes with patterned by Pt on top and covered by AlN. The Pt deposited on these two membranes or islands are dual-purpose temperature sensors and heaters. One side of a sample can be attached to each of the two islands. In this way 1-D heat flow can be established in the material to be tested. Covering the islands with AlN enhances the uniformity of temperature on each sensor. Moreover, AlN is an excellent electrical insulator, and it protects the platinum sensors from different sources of doping such as gallium ions used for patterning, depositing, mounting, or demounting different samples on the islands. This ensures the thermo-electric properties of the sensors on the platform do not change after each measurement. Using this design, it is demonstrated that one platform can be used for measurement of a silicon slab and then a separate measurement of a 1-D PnC fabricated from the same sample. The 1-D PnC had a Si-W structure that was fabricated using a Focused Ion Beam (FIB) and a Gas Injection System (GIS) capable of depositing W.
Integration of Steam Power Plant With Site Utility System Using a New Cogeneration Targeting Method
Authors: KhoshgoftarManesh Mohammad Hasan , Abadi Sajad Khamis , Ghalami Hooman , Amidpour Majid
Published: October 2013

The purpose of a steam power plant usually is power production; however, it can work as a dual-purpose plant with the production of steam and power simultaneously. The aim of this paper was to find the optimum integration of steam power plant as a source and a site utility system as a sink of steam and power. Estimation of cogeneration potential prior to the design of the central utility system for site utility systems is vital to set targets on the site fuel demand as well as heat and power production. In this regard, a new cogeneration targeting model was developed for the integration of steam power plant and site utility of the process plant. The new procedure for finding the optimal integration was proposed based on new cogeneration targeting. In addition, a modified Site Utility Grand Composite Curve (SUGCC) diagram was proposed and compared with the original SUGCC A steam power plant and a process site utility was considered as a case study. The applicability of the developed procedure was tested with other existing design methods, STAR® and Thermoflex software through a case study. The proposed method was shown to give comparable results and the targeting method was used for obtaining optimal integration of steam levels. Identifying optimal conditions of steam levels for integration is very important in the design of utility systems since the selection of steam levels in steam power plants and site utility for integration heavily influence the potential for cogeneration and energy recovery for the site. In this work, the integration of steam levels of steam power plant and site utility system were carried out in a case study, in which the usefulness of the this method was clearly demonstrated for reducing the overall energy consumption for the site.
Performance of a Thermoelectric Adsorption Heat Pump Vis-à-Vis Thermoelectric Device and Adsorption Heat Pump for Electronics Cooling Applications
Authors: Sinha Ashish , Joshi Yogendra
Published: October 2013

Performance of ‘ThermoElectric (TE)’, ‘ThermoElectric-Adsorption (TEA)’ and Adsorption heat pumps has been compared, theoretically, for identical conditions. The TEA heat pump uses TE devices to drive heat regeneration for its adsorption cycle. While this increases the COP of the TEA heat pump, it also highlights the need to investigate if a TE device, when applied alone, could have outperformed the TEA and the Adsorption heat pumps. This becomes important in the context of cooling applications that only require cooling of a few degrees below ambient, and in cases where the ambient environment is thermally harsh. In the first context the TE devices pump heat across a lesser temperature difference with good COP that may outweigh the COP of a TEA or an Adsorption heat pump, in the second, the performance of TE device deteriorates due to high temperatures, and gains in overall COP of TEA heat pump due to heat regeneration become marginal. A heat rejection temperature range of 50 to 200 °C is considered for this investigation. Mathematical models for formulation of the COP of these systems are constructed and compared. It is observed that a TE device is preferable for cooling 20–30°C below the ambient. Beyond this range a TEA chiller is a good option.
Development of a 240,000 kg/Day Hydrogen Pipeline Centrifugal Compressor for the Department of Energy’s Hydrogen Delivery and Production Program
Authors: Di Bella Francis A. , Fairman Kevin D.
Published: October 2013

Concepts NREC has completed the detailed design of a six-stage hydrogen compressor rated for industrial gas pipeline service. A single-stage prototype system has also been designed to enable the controlled laboratory testing of the mechanical elements of the compressor subsystems. The project has successfully met the Department of Energy’s technical objectives including:

• Develop and demonstrate an advanced centrifugal compressor system for high-pressure hydrogen pipeline transport to support the DOE’s strategic hydrogen economy infrastructure plan.

• Deliver 100,000 to 1,000,000 kg/day of 99.99% hydrogen gas from generation site(s) to forecourt stations.

• Compression from 350 psig to 1,000 psig or greater.

• Reduce initial installed system equipment cost to less than $9M (compressor package of $5.4M) for 240,000 kg/day system by FY 2017.

• Reduce package footprint and improve packaging design.

• Achieve transport delivery costs below $1–2/GGE (the DOE’s target as given in the original FOA).

• Reduce maintenance cost to below 3% of Total Capital Investment by FY 2017.

• Increase system reliability to avoid purchasing redundant systems.

• Maintain hydrogen efficiency (as defined by the DOE equal to 1-Compression Specific Energy/Hydrogen High Heating Value) to 98% or greater.

• Reduce H2 leakage to less than 0.5% by FY 2017.
Storage Power and Efficiency Analysis Based on CFD for Air Compressors Used for Compressed Air Energy Storage
Authors: Zhang Chao , Simon Terrence W. , Li Perry Y.
Published: October 2013

The compression process in a piston cylinder device in a Compressed Air Energy Storage (CAES) system is studied computationally. Twelve different cases featuring four different compression space length-to-radius aspect ratios and three different Reynolds numbers are studied computationally using the commercial CFD code ANSYS FLUENT. The solutions show that for compression with a constant velocity, the compression can be approximated by a polytropic pressure vs. volume relation. The polytropic exponent, n, characterizes the heat transfer and temperature rise of the air being compressed. For the cases computed, it varies from 1.124 to 1.305 and is found to be more affected by Reynolds number and less by the length-to-radius ratio. Since the efficiency and storage power of the compressor depend on pressure vs. volume trajectory during compression, they are written as functions of the pressure rise ratio and the polytropic exponent, n. The efficiency is high at the beginning of the compression process, and decreases as the compression proceeds. The effect of temperature rise or heat transfer on efficiency and storage power is shown by comparing the efficiency and storage power vs. volume curves having different n values. Smaller temperature rise always results in higher efficiency but lower dimensionless storage power for the same compression pressure ratio. The storage power is used in this study to distinguish the compression process effect (n effect) and the compressor’s size effect on the storage power. The likelihood of flow transitioning into turbulent flow is discussed. A k–ε Reynolds Averaged Navier Stokes (RANS) turbulence model is used to calculate one of the larger Reynolds number cases. The calculated polytropic exponent was only 0.02 different from that of the laminar flow solution. The CFD results show also that during compression, complex vorticity patterns develop, which help mix the cold fluid near the wall with the hot fluid in the inner region, beneficial to achieving a higher efficiency.
Effect of Mean Grain Size in the Time of Flight for Lcr Waves
Authors: Buenos Alexandre Aparecido , dos Santos Auteliano Antunes , Pereira Paulo , Santos Cleudiane Soares
Published: October 2013

The ultrasonic methods are widely used for evaluation of materials for its inexpensive and practical features. Among the largely used ultrasonic methods is the Critically Refracted Longitudinal Waves (Lcr), which applies longitudinal bulk waves travelling right below the surface, parallel to it. The method can be used to measure stresses near the surface through acoustoelasticity. However, the materials microstructure directly influences the propagation of these waves. The mean grain size is one of the factors that affect the wave speed. The purpose of this paper is to evaluate the effect of mean austenitic grain size in the time of flight (TOF) of Lcr wave. Samples (CDPs) of ASTM A36 steel were manufactured with dimensions of 5/8″ × 6″ × 12″. These were submitted to heat treating at the different temperatures ranges and cooled in air to generate different grain sizes. The results were compared to the grain size estimated in the literature and obtained from optical microscopy. The study showed a clear dependence of TOF on mean austenitic grain size for ASTM A36 steel. Such effect has to be studied to allow stress measurements with Lcr waves.
The Integrated Heat Storage Flash Boiler (HSFB): Review, Principles, Design and Testing
Authors: Lior Noam , Girbal-Puig Albert
Published: October 2013

Systems that store heat in a liquid that can generate vapor for various applications by flash evaporation, sometimes known as steam accumulators, are a relatively simple way for integrated heat storage and vapor/steam generation. Applications include buffering of the transient heat supply and demand in conventionally-fuelled boilers, locomotives and steam power generation systems and more recently in solar thermal power. The information available about this type of heat storage was mostly about steady state operation with little attention to the flash evaporation aspects. In this paper we describe the state of the art and a well-instrumented facility for the experimental study of a variant of such systems, the Heat Storage Flash Boiler that includes a 19.28 m3 storage/flash tank, which was developed by us for experimental examination of its storage and discharge performance for temperatures between 65 °C and 120 °C and pressures from 0.5 to 2 bars (50–200 kPa).. The applicability of such a facility as a generator of steam for feeding a turbine or other purposes has been demonstrated. Flashing has been induced at water temperatures between 80 °C and 100 °C. At 97 °C, the average flow rates obtained ranged between 14 kg/hr for a driving pressure drop of Δpf = 3.2 cm Hg (4.266 kPa), and 390 kg/hr for Δpf = 5.1 cm Hg (6.799 kPa). Specific attention was paid to key issues including the flash evaporation phenomenon, conditions for choked flow of the steam and for mist entrainment, and need and ways for the storage water deaeration. Detailed results for the experimental runs, and the mass flow generation rate of water evaporated was well-correlated to the driving pressure drop for flashing, Δpf. The experiments have provided useful information about the associated heat storage issues and flash steam generation phenomena. Basic considerations and methods for the design of integrated thermal storage/steam generation systems, the Heat Storage Flash Boilers are presented.
Energy and Exergy Analysis of an Air Conditioning System Using the Mixture of Outdoor and Return Air
Authors: Kilicarslan A. , Kurtbas I.
Published: October 2013

Energy and exergy analysis of the air conditioning systems employing the mixture of outdoor and return air (ACOR) are presented. The equations of heat transfer rate and exergy destruction are developed for ACOR according to the system parameters of moist air and condensate water. The effects of the incoming air dry bulb temperature to the coil and relative humidity, and leaving air dry bulb temperature from the coil on the heat transfer and exergy destruction are investigated by means of a computer code developed. The heat transfer from the air to the coil increased as the incoming air dry bulb temperature and relative humidity increased while the heat transfer decreased with the increase in the leaving air dry bulb temperature. The exergy destruction of the moist air increased as the incoming air dry bulb temperature increased, but it decreased with the increasing values of incoming air relative humidity values.
Discovering Irregular Diagnostic Proper Orthogonal Decomposition Signatures in Healthy Marine Ball Bearings
Authors: Georgiou Ioannis T. , Kintzios Nikolaos
Published: October 2013

Presented is a structural health condition diagnosis based on optimal space-time decompositions of ensembles of acceleration signals developed in the complex physical domain of marine ball bearings when interrogated by a set of diagnostic impulsive forces. Ensembles of diagnostic forces and ensembles of collocated responses acceleration signals are decomposed into proper orthogonal modes. Typical inner and ensembles of nondestructive impact diagnostic forces covering three times the inner and outer races are strongly dominated by a single POD mode with uniform spatial distribution and a sharp pulse time modulation. There exist high order modes with very small amount of energy. This indicates that the impact response of the suspended ball bearing depends slightly on the impact location. Diametrically opposite, the typical ensemble of radial acceleration signals collected at a point on the outer race has a very broad POD energy spectrum. All POD modes have energy fractions of the same order and irregular (no periodic) space modulations. Despite this spatial irregularity, all POD spatial modulations have astonishingly common statistical properties: nearly zero mean values, and nearly identical standard deviations at the value level of the uniform spatial distribution of the dominant POD mode of the ensembles of diagnostic forces. The result is that the healthy ball bearing spreads nearly evenly the energy of collocated acceleration signals to a large number of POD modes. The analysis aims at gaining a basic understanding of the behavior of collocated acceleration signals developed in the complex domains of multi-body flexible structures with applications in structural health monitoring of marine-aeronautical machinery critical elements such as propellers, bearings, brakes, clutches and gearboxes.
Effects of the Extent of Coil Embolization on Flow Stagnation in Cerebral Aneurysms
Authors: Otani Tomohiro , Nakamura Masanori , Fujinaka Toshiyuki , Hirata Masayuki , Kuroda Junko , Shibano Katsuhiko , Wada Shigeo
Published: October 2013

Coil embolization is one of the most popular methods to treat cerebral aneurysms. We investigated hemodynamics in differently positioned aneurysms coiled at various volume embolization ratios (VER) to determine the effective VER in terms of flow stagnation. Simulations were conducted for patient specific aneurysm and idealized aneurysm. Porous media modeling was used to describe blood flow within the coil-embolized aneurysm. The ratio of flow stagnation volume to aneurysm volume (stagnant volume ratio, SVR) was analyzed to quantify the efficacy of coil embolization. The results showed that SVR tended to increase with increasing VER for both patient-specific and idealized aneurysms. For the idealized model, SVR was almost 100% at 20% of VER. In contrast, SVR in the patient specific aneurysm was approximately 40% for VER of 20%. These results suggested the importance of taking account of geometrical features of aneurysms when treating them by coil embolization.
Graetz Problem Using FENE-P Fluids Without Viscous Dissipation
Authors: Abdelkader Filali , Khezzar Lyes , Siginer Dennis A. , Nemouchi Zoubir
Published: October 2013

A numerical investigation of heat transfer with viscoelastic fluid based on the FENE-P model in the entrance region of an axisymmetric pipe is carried out to analyze the influence of the rheological parameters on heat transfer enhancement with negligible axial heat conduction and viscous dissipation. Numerical simulation is conducted using the finite element based software Polyflow. The analysis considers a constant wall heat flux boundary condition and shows that an increase in fluid elasticity raised the normalized heat transfer coefficient due to the increased level of shear-thinning behaviour. But increasing the extensibility parameter L2 leads to a decrease in Nusselt number.
Rotor Torsion Vibrations in the Presence of Continuous Stator Contact
Authors: Vlajic Nicholas , Liu Xianbo , Karki Hamad , Balachandran Balakumar
Published: October 2013

The purpose of this study is to examine the torsion response of a rotor while in continuous contact with a stator for both forward synchronous whirling and backward dry-friction whirling. Experimentally obtained torsional strain data for both of these motions are presented, and the results indicate that the major contributions to the motions occur at the drive speed fd, twice the drive speed 2fd and the first torsional natural frequency ft for forward whirling. During backward whirling, the dominant response occurs at the drive speed fd and the sum of the whirl speed plus the drive speed at fw + fd. A distributed-parameter model in combination with a force-interaction model is used to capture the qualitative aspects of the system response. Simulations with this model reveal that the torsional vibrations are excited by stick-slip forces while undergoing backward whirling. Numerical and experimental results also show that motion at the first torsion natural frequency is the dominant component during forward whirling.
Towards a Self-Calibratable MEMS Absolute Temperature Sensor: A Theoretical Study
Authors: Chigullapalli Aarti , Clark Jason V.
Published: October 2013

In this paper, we present a theoretical description of a novel self-calibratable MEMS absolute temperature sensor. Our analysis suggests that the sensor might provide accurate and precise measurements over a large range of temperatures. Due to the high accuracy and precision required for some experiments and devices, such as studies involving fundamental laws or sensor drift due to thermal expansion, accurate temperature sensing is necessary. Conventional temperature sensors require factory calibration, which significantly increases the cost of manufacture. Using the equipartition theorem, nanotechnologists have long determined the stiffness of their atomic force microscope (AFM) cantilevers by measuring temperature and the cantilever’s displacement. Since we have determined how to measure MEMS stiffness, we propose that the reverse can be done, i.e. determine temperature by measuring MEMS stiffness and displacement. In this paper we describe our method for accurately and precisely measuring nonlinear stiffness and expected displacement. We also provide an expression for quantifying the uncertainty in measuring temperature.
Modeling the Thermomechanical Interaction Between an Atomic Force Microscope Cantilever and Laser Light
Authors: Chigullapalli Aarti , Clark Jason V.
Published: October 2013

In this paper, we present the first computational model of the thermomechanical interaction between an atomic force microscope (AFM) cantilever and laser light. We validate simulation with experiment. Design parameters of our model include AFM laser power, laser spot position, and geometric and material properties of the cantilever. In the area of nanotechnology, the laser beam deflection method has been widely used in AFMs for detecting the cantilever’s deflection and resonance frequency. The laser deflection method consists of reflecting a laser beam off of an AFM cantilever onto a photo diode, which is converted to a voltage signal. Deflection of the cantilever results in a change in the laser reflection angle and a change in voltage signal. The mechanical properties of the cantilever affect the amount of deflection. Although much work has been done on increasing the sensitivity of the AFM, little work has been done on investigating the thermal effect of the laser-cantilever interaction. We observe that laser-induced thermal expansions in the AFM cantilever are measureable. Our simulated results suggest that both the laser power and spot positions significantly change the resonant response of the cantilevers. The resonance response is critical for the AFM tapping mode. In considering various laser powers, we observe that as we increase the power, the average temperature of the beam increases, which causes a decrease in resonance frequency. In considering various laser reflection spot positions, we find that as the laser spot moves away from the clamped end of the cantilever, the dissipation to the sample which is 6 m below the cantilever tip decreases, causing an increase in temperature but decrease in material softening. The results of our models are close to the experimental results with a relative error of 0.1%.
Multiscale Modelling of Non-Crimp Fabric Composites
Authors: Asp L. E. , Marklund E. , Varna J. , Olsson R.
Published: October 2013

Damage initiation and evolution in NCF composites leading to final failure includes a multitude of mechanisms and phenomena on several length scales. From an engineering point-of-view a computational scheme where all mechanisms would be explicitly addressed is too complex and time consuming. Hence, methods for macroscopic performance prediction of NCF composites, with limited input regarding micro- and mesoscale details, are requested. In this paper, multi-scale modelling approaches for in-plane transverse strength of NCF composites are outlined and discussed. In addition a simplistic method to predict transverse tensile and compressive strength for textile composites featuring low or no fibre waviness is presented.
A Parallel Coupled Ordinates Method for Rarefied Gas Dynamics Simulations
Authors: Das Shankhadeep , Yildirim Battalgazi , Mathur Sanjay R. , Alexeenko Alina , Murthy Jayathi Y.
Published: October 2013

Deterministic solution techniques for non-equilibrium rarefied flows in RF MEMS switches are frequently based on the ellipsoidal statistical Bhatnagar-Gross-Krook (ESBGK) form of the Boltzmann kinetic equation. These numerical schemes involve the sequential solution of the distribution function in velocity space. However, these schemes have poor convergence rates, especially at low Knudsen numbers, because of the explicit coupling of the distribution functions in velocity space. Furthermore, parallel implementation of these schemes is inefficient, making simulation of real-life devices practically impossible. In this paper we describe the parallel performance of a recently-developed numerical procedure called the coupled ordinates method (COMET) to solve ESBGK equations. In this method, the distribution functions for all velocity ordinates are strongly coupled at each physical point, resulting in an implicit solution procedure in velocity space. The coupled procedure is used as a relaxation sweep in a geometric multigrid scheme to promote spatial coupling. Results show that COMET gives excellent CPU scaling on multiple processors even for very small workload per processor. The solver is also shown to have very good strong and weak scaling characteristics. The parallel COMET solver also gives significantly faster solutions than the parallel implementation of the conventional sequential solution procedure. It is believed that the parallel COMET solver can become an efficient tool to model real-life RF MEMS switches.
Inhomogeneous Deformation Examples and Applications of Light Activated Shape Memory Polymers
Authors: Sodhi Jaskirat S. , Moon Swapnil , Rao I. Joga
Published: October 2013

Light Activated Shape Memory Polymers (LASMP) are recently developed innovative materials defined by their capacity to store a deformed (temporary) shape and recover an original (parent) shape. This change in shape and the return to original shape is achieved by exposing the polymer to light at different wavelengths. These unique properties have led to the use of LASMP’s in a wide variety of applications. These SMP’s have a great potential in the biomedical industry as well as the aerospace industry.

In the past, the authors have introduced a constitutive model to model the mechanics of these LASMP [1] and used it to solve a few cases of boundary value problems of interest. In this paper, the developed model is used to solve some other inhomogeneous deformation boundary value problems.
Numerical Investigation on Impact Energy Absorption of Single-Walled Carbon Nanotube Reinforced Composites
Authors: Sun Lingyu , Zhang Jian , Leng Dingxin
Published: October 2013

With the exceptional mechanical properties, carbon nanotubes (CNTs) are considered to be attractive candidate reinforcements for composite materials and to have potential applications in improving the energy absorption capability of matrix material. However, it is still difficult to reveal the micro-mechanisms of the impact energy absorption of CNT-reinforced composites by experiments, hence, the numerical investigation is helpful. In this paper, a unit cell of single-walled CNTs (SWCNTs) embedded in metal matrix is modeled by nano-scale finite element method. Under impact loads, the failure modes of a single SWCNT and the SWCNT in matrix are predicted, respectively, and several possible energy absorption mechanisms are explained and compared. The investigation shows that, the metal matrix restraints the radial expansion of the SWCNT and therefore improves its crush buckling resistance, and makes it absorb more energy before collapse. The specific energy absorption of SWCNTs-reinforce composites increases with the increasing volume fraction of SWCNTs in both matrixes, and ascends more quickly in magnesium alloy than in aluminum alloy matrix.
Droplet Vaporization in Turbulent Convective Flows With Temporal Variation of Pressure and Temperature
Authors: Abou Al-Sood Maher M. , Saleh Wael F.
Published: October 2013

This paper presents a numerical model to investigate the effect of temporal variation of pressure and temperature on vaporization process of a single droplet exposed to a turbulent freestream of gaseous nitrogen. As a typical case, the evaporation rate and droplet life time of n-heptane droplet during adiabatic compression process and isobaric expansion process of a standard diesel cycle are investigated numerically. The numerical model is based on solving complete sets of time-dependent conservation equation of mass, momentum, energy, and species concentration in both gas-phase and liquid-phase. The turbulence terms in the conservation equations of the gas-phase are modeled by using the shear-stress transport (SST) model. The system parameters such as pressure and temperature at the beginning of fuel injection (i.e. represented by engine speed, RPM, and compression ratio, RC), and turbulence intensity are varied to provide a wide range of test conditions. To account for variation of temperature, variable thermo-physical properties, gas and liquid phase transients and radiation are considered. Also, the effects of high-pressure such as non-ideal gas behavior, solubility of gases into droplet and pressure dependence of gas- and liquid-phase thermo-physical properties are considered. Results of temporal variation of pressure and temperature are compared with those of isobaric and isothermal conditions.
Neuron-Fuzzy-Based Acoustic Emission Output Parameters Prediction for Rotary Device Monitoring
Authors: Refahi Oskouei A. , Esmaeili M.
Published: October 2013

Online fault prediction in bearing plays a key role in industry automation for higher productivity and product quality. In this way Acoustic Emission Technology (AET) is one of the earliest documented applications that has been developed to rotating machinery monitoring. Predictions of output parameters in journal bearing are Junction of operational parameters in test–rig. In this paper an experimental work which is set-up by different load and speed and three viscosity type of one oil has been used for hydrodynamic bearing. During the tests, acoustic emission output parameters (AE RMS, ABS energy) were obtained. Adaptive Neuro Fuzzy Interface System (ANFIS) as an advanced statistical method has been applied to predict the relationship between input and output parameters. In this way, obtained data was trained and the precision of the predicted model was tested to find efficiency of the proposed method. The results show that this method can predict AE output parameters by 0.1% error. In this way the effectiveness, as well as the ability of the proposed method for data mining is evaluable.
Heat Insulating Materials Thermal Conductivity Determination by Means of Comparison With a Standard Plate of Known Conductivity
Authors: Huang Chyouhwu Brian , Chen Hung-Shyong
Published: October 2013

Due to the soaring energy prices, the cost to maintain a basic living standard has increased, therefore choosing right insulated materials when building a new house/appliance is important. The heat transfer coefficient plays a vital role; therefore, developing an effective, accurate, and low cost testing machine is an important issue. This is also the goal of this research. The testing apparatus developed can be used to measure the thermal conductivity as a basis for the choice of the materials. The heat conduction testing equipment was designed using “the thermal conductivity comparison with a known conductivity” method in addition to the basic heat conduction theory. For the best results, several parameters were used to fine-tune the operating conductions, such as cooling flow rate, heat source temperature, etc. Three types of materials were used as the sample for verifying the accuracy of the developed apparatus: gypsum board, silicon cement and PE polyethylene foam. Four heat sources temperatures were tested: 30°C, 35°C, 40°C, and 45°C. Two cooling flow rates were used: 108 liter/hour and 90 liter/hour. In the end, ANSYS was used to validate the testing results. The testing results show that the measured thermal conductivity is accurate. Equilibrium can be reached faster when testing with high cooling flow rates. The best hot plate temperature is 30°C.
Teaching of Extended Surface Heat Transfer Through Laboratory Experiments
Authors: Eveloy Valerie , Rodgers Peter , Bojanampati Shrinivas
Published: October 2013

This paper describes a hands-on laboratory thermofluid project which is taught as part of a one-semester, junior-level mechanical engineering course titled Core Measurements Laboratory. The experiment focuses on the characterization of multi-mode heat transfer from a range of cartridge-heated fin geometries cooled by conduction, natural convection and radiation. The project involves the design and construction of the test facility, experimental characterization of fin heat transfer, and comparison of experimental results with corresponding analytical and numerical predictions, with a formal report submitted on completion. The project is undertaken by a team of four students over a five-week period. Emphasis is placed on highlighting potential discrepancies between measurement and predictions, which are inherent in the test configurations considered, reflecting realistic engineering situations. Sample measurement and analysis results are reported in this paper. The teaching strategy employed to integrate fundamental theories with hands-on experiences is described. The effectiveness of the laboratory project in enhancing student learning of heat transfer, engineering analysis of discrepancies between predictions and measurements, and project management skills was demonstrated by monitoring student performance improvements over the duration of the project.
Why Require Ethics in Engineering?
Authors: Flumerfelt Shannon , Alves Anabela C. , Kahlen Franz-Josef , Siriban Manalang Anna Bella
Published: October 2013

This theoretical paper will provide a review of the literature regarding the need for ethics in the workplace and how taxonomical ethical development can be used in engineering education. In fact, advocacy to educate for ethics in engineering education by design is discussed as a solution to this problem. By spiraling ethical competency development into engineering education as a body of practice, rather than as a theory of knowledge, it is possible to integrate engineering “hard science” content with engineering “soft science” competency. This means that current programs’ scopes and sequences may remain in place, with recommended changes in pedagogy.
Spurious Signals in the Thermal MEMS Gyroscope
Authors: Shooshtari Pooneh , Bahari Jamal , Khosraviani Kourosh , Leung Albert , Jones John
Published: October 2013

The operational principle of a thermal MEMS (Micro Electro-Mechanical Systems) gyroscope was reported in Hilton Head 2010 [1]. In the current work we describe two factors that can produce a spurious rotation signal in gyroscopes of this type. These factors are, firstly, distortion or asymmetric placement of the heating elements or temperature sensors; secondly, the effects of linear acceleration and/or gravity on the fluid flow inside the device, and hence on the gyroscope output. In order to simulate the thermal gyro and the origin of these spurious signals, a mathematical model is built and developed through the COMSOL CFD package. The spurious signals predicted by this simulation are shown to correspond to experimental measurements. Alternative cavity shapes are investigated and simulated as a mean of suppressing the spurious signal.