bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat/Mass Transfer to a Drop Translating in a Perpendicular Electric Field
Authors: Abdelaal Mohamed R. , Huzayyin Omar A. , Jog Milind A. 
Published: March 2016

Enhancement of heat or mass transport in a spherical drop of a dielectric fluid translating in another dielectric fluid in the presence of uniform electric field is investigated. The internal problem or the limit of the majority of the transport resistance being in the dispersed phase is considered. The transient energy conservation equation is solved using a fully implicit finite volume method.
In the literature, there is a plenty of studies that had been carried out when the electric field acts in the same plane of translation. In this paper, considering creeping flow regime, numerical computations have been conducted when the electric field acts perpendicular to the plane at which translation acts. As such the flow is no longer a two dimensional flow as a third component velocity comes to picture. At the first glance, thoughts of transport enhancement come to mind on the presence of a third velocity component that might promote mixing and consequently enhance transport effectiveness. Results are expressed in terms of the Nusselt number. Nusselt numbers are plotted in terms of Peclet number, Fourier number and the parameter L which is defined as the ratio of the maximum electric-field-induced surface velocity to translation-induced surface velocity. The code was validated by comparing, results for Peclet numbers of 500 and 1000 to corresponding cases available in literature. Results showed good agreement with previous results. A 3-D grid of 20×40×60 has been considered to cover the computational domain. A grid independence study has been carried out by doubling the whole grid. Results show acceptable results compromising accuracy and code running time. The effect of electric field is expressed in terms of parameter L.
For low Peclet numbers (Pe ≤ 250), the application of electric field perpendicular to the plane at which translation acts leads to enhancement of heat/mass transport compared to that in pure translation. Such enhancement is about the same when the electric field and translation act in the same plane. On the other hand, for moderate Peclet numbers (Pe= 250∼1000), the transport enhancement is significant when compared to the enhancement obtained by an electric field acts in the same plane of action of translation as well as pure translation. These results can be understood by comparing time scales for diffusion and convection. When Peclet number is low the convection time scale is very large and hence mixing is not that effective in promoting heat / mass transfer. Whereas for moderate Peclet number, when the convection time scale gets smaller, heat/mass transfer is considerably enhanced compared to low Peclet numbers.
Characterization of Material Properties for Multi-Scale Polymer Composites Extruded From Straight and Divergent Die Geometries Using Various Filler Concentrations
Authors: Nixon Jason R. , Lempert Inna , Choi Hyunjo , McFarlane Jeremy , Bigio David I. 
Published: March 2016

The addition of nano-scale and micro-scale fillers has been proven to increase tensile and thermal properties in polymer composites. Orientation of high aspect fillers, however, has not been studied before despite being crucial to altering physical properties. When fibers are included during extrusion, they tend to align in the direction of the flow. This phenomena leads to longitudinal improvements in mechanical properties, and thus provides great benefits in some applications; however, it is beneficial to have improved properties in the transverse direction as well. Therefore, it is crucial to study reorientation phenomena in composites.
The purpose of this experiment is to study property enhancement resulting from fiber structure. The material properties are compared for the range of weight percentages of fillers. This is done for the purpose of finding an ideal fill concentration. Two dies are used to study different orientation distributions: straight and divergent. Thermal and tensile properties and optical micrographs are analyzed and compared.
Composites were processed on a Coperion ZDSK-28mm co-rotating, fully-intermeshing, twin-screw extruder. Polybutylene terephthalate (PBT) was used as the polymer matrix. 0 W% to 2 W% multi-walled carbon nanotubes (CNTs) and 0 W% to 30 W% carbon microfibers (CMFs) were used as fillers.
Preliminary results showed a clear trend in increased tensile strength of the composite with the increase of concentration of CMFs and CNTs in the slit die up to 25 W% CMF. After 25 W% CMF, however, there was a depreciation in properties. Similarly, thermal conductivity results have shown a clear peak at 25 W% CMF with 30 W% showing a decrease in thermal properties.
Preliminary results for the divergent die showed that, with addition of carbon microfibers to the polymer matrix, thermal properties of the composite increased up to 15 W%, then dropped and increased again as more CMFs were added. In addition, on average, material extruded through the divergent die showed better results of thermal conductivity than that extruded through the slit die. This indicates that when using a diverging die, fiber become oriented perpendicular in relation to the direction of the flow, thus improving heat flow in the transverse direction.
Static Response of Microbeams due to Capillary and Electrostatic Forces
Authors: Bataineh Ahmad M. , Ouakad Hassen M. , Younis Mohammad I. 
Published: March 2016

Micro-sensors or micro-switches usually operate under the effect of electrostatic force and could face some environmental effects like humidity, which may lead to condensation underneath the beams and create strong capillary forces. Those tiny structures are principally made of microbeams that can undergo instabilities under the effect of those created huge capillary forces. In fact, during the fabrication of microbeams, there is an important step to separate the beam from its substrate (wet etching). After this step, the microstructure is dried, which may causes the onset of some droplets of water trapped underneath the beam that could bring about a huge capillary force pulling it toward its substrate. If this force is bigger than the microbeam’s restoring force, it will become stuck to the substrate.
This paper investigates the instability scenarios of both clamped-clamped (straight and curved) and cantilever (straight and curled) microbeams under the effect of capillary and/or electrostatic forces. The reduced order modeling (ROM) based on the Galerkin procedure is used to solve the nonlinear beam equations. The non-ideal boundaries are modeled by adding springs. The volume of the fluid between the beam and the substrate underneath it is varied and the relation between the volume of the water and the stability of the beam is shown. An analysis for the factors of which should be taken in to consideration in the fabrication processes to overcome the instability due to huge capillary forces is done. Also the size of the electrode for the electrostatic force is varied to show the effect on the micro-switch stability. A variation of the pull-in voltage with some specific beam parameters and with more than one case of electrode size is shown. It is found that capillary forces have a pronounced effect on the stability of microbeams. It is also found that the pull-in length decreases as the electrode size increases. It is also shown that the pull-in voltage decreases as the amount of fluid underneath the beam increases.
Thermal Property Measurement of Thin Fibers: A Direct Approach
Authors: Munro Troy , Xing Changhu , Ban Heng , Copeland Cameron , Lewis Randolph , Glorieux Christ 
Published: March 2016

Fiber thermal characterization is often accomplished by indirect means, such as embedding the fiber in a matrix, measuring the thermal response of the composite, and relating for the contributions of the fiber and matrix to the overall behavior or measuring bundles of fibers. To improve the accuracy of the composite-based or bundle-based techniques, several different contact (hot wire and dc thermal bridge) and non-contact (Raman shift and IR thermography) methods have been developed to directly measure the thermal properties of individual fibers. To improve on the shortcomings of these methods, this paper presents the experimental results of an improved transient electrothermal (TET) method, as well as a 3ω-based method that better accounts for all sources of heat transfer, particularly heat loss by radiation. The incorporation of radial radiation heat loss becomes a significant factor as the size of the fibers decrease. This work describes practical applications of the methods to measure the properties of the fibers, including sample preparation for electrically conductive and non-conductive samples, data acquisition and calibration, data analysis, and sample property determination.
Results include validation of the methods with electrically conductive (platinum) and non-conductive (glass) fibers to improve upon the initial validation of the generalized electrothermal method which focused only on short, conductive fibers. The axial thermal conductivity and diffusivity of several high performance fibers are presented. The novelty of this paper is that it serves as both a compilation of previous research on the transient electrothermal and 3ω methods [1–6], measurements of new silk fibers, and practical information associated with the methods that improve the accuracy of the measured thermal property, as well as presenting thermal properties of additional fibers (carbon fiber and natural and synthetic spider silks).
To improve upon the long sample preparation time required for the TET and 3ω methods, future work focused on the development of a quantum dot-based photothermal fluorescence method is presented.
Performance of Temperature Controlled Perimeter and Row-Based Cooling Systems in Open and Containment Environment
Authors: Nemati Kourosh , Alissa Husam , Sammakia Bahgat 
Published: March 2016

The continuous increase of data center usage is leading the industry to increase the load density per square foot of existing facilities. High density (HD) IT load per rack demands bringing the cooling source closer to the heat load in contrast to room level air cooling. For high density racks, the use of in-row cooling systems is becoming increasingly popular. In-row cooling can be the main source of cooling for a data center or work jointly with perimeter cooling in what is called a hybrid cooled room level system. Also, hot or cold aisle containment can be integrated with perimeter cooling and used throughout the data center to reduce the mixing of hot and cold air. Currently, there has not been much work comparing the performance of in-row cooling in open versus contained environments.
The present work builds on a previous study where the interaction of perimeter and row-based cooling was evaluated for a cold-aisle containment (CAC) environment. Previously, the benefit of using row-based cooled in an aisle has not been compared with an aisle in open conditions. Here, we numerically investigate the performance of in-row coolers in both opened and cold-aisle contained environments. Groups of IT equipment that differ in air flow strength are used to provide the heat load. Empirically measured flow curves for common IT equipment are employed to provide simplified models of the IT equipment in the CFD software used. The steady state analysis includes information provided in the manufacturer’s specifications such as heat exchanger performance characteristics. The model was validated using a new data center laboratory with perimeter cooling. A single aisle of the data center is modeled to reduce the computational time, and the results are generalized. The cold aisle contains 16 racks of IT equipment distributed on both sides. In addition, the aisle contains 2 power distribution units. Full details are incorporated in the computational model. A single Liebert® CW114 CRAC unit provides the perimeter cooling in the data center. The model captures the particular air flow behavior in the cold aisle when row-based cooling is utilized. Correlations are derived to predict the ability of air cooling units to maintain set points at different air flow rates. The effect of leakage is also considered.
Investigation of Non-Destructive Examination for Mechanical Damage of FRP
Authors: Ono Keisuke , Fujii Yoshimichi , Wada Akihiro 
Published: March 2016

Nowadays, fiber reinforced plastic (FRP) has been widely used in many areas such as auto mobile, airplane and marine vessel due to its high specific strength, good corrosion resistance, relatively low cost and so on. However, it still remains unknown that what kind of damage will happen in the internal structure when an automobile, which is made from FRP, has a slight impact with something such as a wall. Then the following road safety of the automobile cannot be guaranteed because certain parts may be exposed to damage in what seems even like a slight impact. In addition, it is well known that initial fracture can bring damage and great effect to the mechanical properties of the FRP material. The novelty of this paper is that the object of this research is micro crack such as transverse crack. While, almost previous report is aimed at delamination. Actually, before the delamination happens, micro crack has already occurred. The mechanical property of FRP is beginning to decrease by delamination. However, when the delamination occurred in the FRP is examined, it is already too late because the delamination can bring great influence to the safety of the FRP products. Therefore, it is important to investigate and detect the presence of micro crack with ultrasonic wave. In this way, some accidents might be avoided. While, because of the variety of the constraints in the fracture mechanism, the damage behavior is very difficult to evaluate and there are rarely researches and data on it. Although damage assessment by visual observation and the durable service life on FRP has become a general tendency in these recent years, the appropriate way of non-destructive examination has not been confirmed yet.
The purpose of this study is to investigate the possibility of non-destructive examination with ultrasonic wave testing for mechanical damage of glass fiber reinforced plastics (GFRP). The possibility of dividing of Lamb wave modes by reducing the thickness of samples was confirmed and the variance of distribution of frequency of S0 mode wave by micro fracture in GFRP.
Convective Electronic Device Cooling Using Microencapsulated Phase Change Material Slurry in Planar Spiral Coil
Authors: Rokni Houman B. , Languri Ehsan M. , Johnson Wayne 
Published: March 2016

The current trend in miniaturization of electronic devises requires more effective thermal management techniques to remove the heat to ensure the maximum performance of the devise. Among all available thermal management techniques for electronic cooling, convective heat transfer cooling has gained attentions due to low cost and maturity in the market. The single-phase convective heat removal technique suffers from the low heat carrying capacity since there is no phase change occurs during the process. On the other hand, Microencapsulated phase change materials (MPCMs) are gaining attention due to their high heat carrying capacity. MPCMs are composed of phase change material (PCM) as the core material that is encapsulated with micrometer size shell materials. The PCM inside the capsules may undergo a phase change as the temperature varies around the melting and freezing temperature points of the PCM. This leads to a significant heat gain/release due to the phase change of the PCM.
In this paper, we are performing a numerical modeling on the performance of MPCMs mixed with single-phase base fluid when pumped through planar spiral coils. From electronic thermal management point of view, it is ideal to have an enhanced coolant that maintain the operating temperature under an allowable level uniformly. The behavior of MPCM slurry when pumped through planar spiral coils reveals unique patterns due to the centrifugal forces. The available data on MPCM slurry through spiral coil heat exchangers show the new patterns of velocity and heat transfer curves that require further investigation and scientific explanations. The current paper studies the steady conditions of flows under laminar regimes at different boundary conditions. A CAD model of a planar coil heat exchanger is developed in SolidWorks. The model is meshed and discretized in order to apply the governing equations into the model. ANSYS Fluent package is used to solve the fluid flow and heat transfer equations inside the geometry. The velocity and temperature profiles along the coil are studied and discussed to quantify the roles of different forces in such flows. The ultimate goal of this study to evaluate the efficacy of utilizing such formulated microencapsulated PCM slurry at different mass concentrations on electronic thermal management considering the cost associated to the added pressure drop when using MPCM slurry.
Axiomatic Design: 30 Years After
Authors: Nordlund Mats , Lee Taesik , Kim Sang-Gook 
Published: March 2016

In 1977, Nam P Suh proposed a different approach to design research. Suh’s approach was different in that it introduced the notions of domains and layers in a 2-D design thinking and stipulated a set of axioms that describes what is a good design. Following Suh’s 2-D reasoning structure in a zigzagging manner and applying these axioms through the design process should enable the designer to arrive at a good design.
In this paper, we present our own experiences in applying Suh’s theories to software design, product design, organizational design, process design, and more in both academic and industrial settings. We also share our experience from teaching the Axiomatic Design theory to students at universities and engineers in industry, and draw conclusions on how best to teach and use this approach, and what results one can expect.
The merits of the design axioms are discussed based on the practical experiences that the authors have had in their application. The process developed around the axioms to derive maximum value (solution neutral environment, design domains, what-how relationship, zig-zag process, decomposition, and design matrices) is also discussed and some updates are proposed.
Frictional Torque Transfer Behaviors of Friction Pads in Wet Clutch Engagement
Authors: Jang Siyoul 
Published: March 2016

For stable frictional torque transfer, wet clutch pads have the functional requirements of a high traction and a low wear rate with positive μ-V frictional characteristics. However, because of the intrinsic negative μ-V frictional characteristics of a friction material that has a static friction coefficient greater than its kinetic friction coefficient, the frictional torque transfer has unstable vibrations during the clutch-pad engagement.
To reduce the vibration mode during the engagement of wet clutch pads, the kinetic friction coefficient should be made greater than the static friction coefficient through modifications in the design parameters as well as in the characteristics of the friction materials. To obtain positive μ-V frictional characteristics, it is important to manipulate the static-friction coefficient, which largely develops in the boundary lubrication stage during the clutch-pad engagement. The formation of the boundary film is described by slip boundary conditions and hydrodynamic lubrication films. It also includes the elastic deformation of the wet pad material due to the contact pressure. The wet clutch pad material is made of a porous structure through which the lubricant can easily spread when the applied load and sliding speed are imposed. The lubrication and the direct contact of the surfaces are simultaneously considered for a frictional torque transfer that lasts for less than one second, depending on the working conditions.
In this study, some of the computational results with a measured μ-V friction coefficient covering both the static and kinetic friction during the wet-clutch engagement are obtained for the lubrication and the direct-contact pressures.
Educating Engineering Students on Probabilistic Risk: Effects on the Perception of Ethics, Professional Responsibility, and Personal Agency
Authors: Gernand Jeremy M. 
Published: March 2016

To better understand how improved understanding of uncertainty and probability concepts in an engineering systems context would affect undergraduate engineering students’ perceptions of professional responsibility and ethics as well as personal agency (one’s ability to affect the outcome of events), an assessment of these principles was conducted during a related course.
A course entitled Engineering Risk Analysis was offered and conducted with a mix of undergraduate Mechanical Engineering, Chemical Engineering, Petroleum Engineering, Environmental Systems Engineering, and Architectural Engineering students. This course presented and trained students in the use of system analysis techniques from the disciplines of Reliability Engineering, Policy Analysis, and Economics for understanding how uncertain circumstances interact with technological systems to produce failures and disasters.
As engineering systems become increasingly complex and command greater quantities of energy, the risk of failures even when very rare, become much more severe. While there have been previous initiatives to increase engineering students’ understanding of statistics, probability, and risk, usually in response to previous disasters, this preliminary study is the first to begin to examine how this kind of knowledge affects engineering student’s perceptions of ethics, responsibility, and their concept of how their own individual decisions affect the potential for the failure of complex systems and the consequences of such failures.
Students completed 5 regular survey-based assessments to judge their qualitative and quantitative skills, personal perceptions of the causes of engineering failures, and the professional and ethical responsibilities of engineers. Analysis of the response variance and a linear regression model demonstrated some significant effects after controlling for education, age, and professional work experience.
Results indicate that questions related to probabilistic understanding of risk demonstrated the most significant change during the course. Indicators of agreement with strong professional ethics and greater professional responsibility as well as personal agency did not significantly change during the course. More importantly, while personal choices on risk did not appear to reflect one’s view of how engineers actually do or should treat questions of risk professionally, the amount of previous technical work experience showed a small positive association with increased agreement on statements of ethical responsibility towards workers and the public. These findings suggest that future research is needed to assess the types of instruction and personal experience that can best encourage the combination of strong ethical responsibility and personal agency that could empower engineering students to act when they have the opportunity to reduce risk to workers, the public, or the environment.