bluuebunny/crossref_metadata_2025 huggingface dataset:
The Determination of Thermal Properties of Paraffin-Based Phase Change Material [PCM] Within a Daylighting Panel
Authors: McCloskey John , Fleischer Amy , Patel Sneha , Ng Rashida
Published: July 2010

The addition of phase change material (PCM) to a transparent polyester panel is used to create an energy absorbing building material that can be used for daylighting. One of the key development needs of this energy efficient material is the identification of the thermal properties. Without a clear understanding of the thermal properties and thermal performance with embedded solid and liquid PCM, design optimization is not possible. This experiment analyzes the thermal conductivity of various mixtures of thermoplastic polyester and PCMs. It was determined that the addition of PCM slightly increases the thermal conductivity of panels when the PCM is solid. Once the PCM has melted, the panel conductivity is lowered.
A Flow Visualization Study of the Jet Dynamics in a Round Jet Impinging on a Foamed Aluminum Porous Media
Authors: DiBella Elizabeth , Azeredo Ian , Yakkatelli Ravi , Fleischer Amy
Published: July 2010

The high surface area of foamed metals makes them an attractive choice for impingement heat sinks. If the jet can effectively penetrate the foam, the high surface area will lead to enhanced thermal performance. However, if the jet fails to effectively penetrate the foam, the surface enhancement effect will be reduced. Previous studies have suggested that for high density foams, the jet does not effectively penetrate the foam and under certain flow conditions may in fact deflect off the foam. In this study, the flow dynamics of round jets impinging on both aluminum foams and solid cubes are studied using smoke wire visualization to identify the effects of Reynolds number and jet exit to surface spacing. The differences in the impinging jet dynamics between the foams and the solid cubes are identified. It is found that the penetration of the impinging flow into the porous media is significantly affected by permeability. As permeability decreases, flow deflection off the impact surface of the foam increases, approaching the fluid dynamics behavior of impact on a solid cube. The jet-exit-to-surface spacing and Reynolds number are also found to significantly affect the flow dynamics.
Bounds on Previsions and Conditional Probabilities on Joint Finite Spaces Under the Assumption of Independence in Imprecise Probability
Authors: Tonon Fulvio , You Xiaomin , Bernardini Alberto
Published: July 2010

The primary difference between precise and imprecise probability theories lies in the allowance for imprecision, or a gap between upper and lower expectations (also called previsions) of bounded real functions. This gap generates a set of probability distributions or measures. As a result, in imprecise probabilities, the notion of independence on joint spaces is not unique; for example, notions of unknown interaction, epistemic irrelevance/independence and strong independence have been proposed in the literature. After introducing the three concepts of independence, various algorithms are proposed to calculate, through the different definitions of independence, both prevision and conditional probability bounds generated by marginal distributions over finite joint spaces. All algorithms are designed to accommodate two different types of constraints that define the sets of marginal distributions: previsions bounds or extreme distributions. Algorithms are applied to simple examples that show the role of the different quantities introduced and the equivalence of the two types of constraints. It is shown that, in epistemic irrelevance/independence, re-writing algorithms in terms of joint distributions turn quadratic optimization problems into linear ones.
Heat Transfer Augmentation of Parallel Flows by Means of Electric Conduction Phenomenon in Macro- and Micro-Scale
Authors: Yazdani Miad , Seyed-Yagoobi Jamal
Published: July 2010

Electrohydrodynamic (EHD) conduction phenomenon takes advantage of the electrical Coulomb force exerted on a dielectric liquid generated by externally applied electric field. The conduction phenomenon can be applied to enhance or control mass transport and heat transfer in both terrestrial and microgravity environments with advantages of simplicity and no degradation of fluid properties for isothermal as well as non-isothermal liquids. This paper numerically studies the heat transfer augmentation of externally driven macro- and micro-scale parallel flows by means of electric conduction phenomenon. The electric conduction is generated via electrode pairs embedded against the channel wall to solely enhance the heat transfer; it is not utilized to pump the liquid. Two cases of Poiseuille and Couette parallel flows are considered where for the former, a constant external pressure gradient is applied along the channel and for the latter, the channel wall moves with a constant velocity. The electric field and electric body force distributions along with the resultant velocity fields are presented. The heat transfer enhancements are illustrated under various operating conditions for both scales.
Moisture Concentration and Temperature Dependence of the Coefficient of Hygroscopic Swelling (CHS)
Authors: Madduri Sushma , Infantolino William , Sammakia Bahgat G. , Park Seungbae , Zhang Haojun , Chaparala Satish C.
Published: July 2010

This paper presents an experimental and computational study done on an epoxy to determine the effect of moisture level and temperature on the Coefficient of Hygroscopic Swelling (CHS). When a non-hermetic package is exposed to a humid environment, the adhesives used in the package absorb moisture and swell. This can induce stresses in the package that can lead to failure. The Coefficient of Hygroscopic Swelling is defined as the ratio of hygroscopic strain to the moisture concentration in the material. It has been found from prior literature that hygroscopic strains are significant and have to be accounted for in reliability modeling [1]. Prior research investigated the measurement of CHS experimentally using techniques such as thermo mechanical analysis (TMA) [1] [2], moire´ interferometry [3], and digital image correlation (DIC) [4]. An experimental method using the TMA technique was used to measure the CHS [1], but further analysis using improved techniques was recommended to get a more precise measurement. One of the goals of this paper was to investigate experimental and numerical techniques that would help better understand various factors that affect the measurement. This paper focuses on measurement of CHS for an epoxy used in optoelectronic packaging. The DIC technique was chosen for measurement of CHS. Moisture loss during the test leads to a change in the moisture concentration in the sample. While it may be thought that the moisture loss during the DIC scan can be assumed negligible due to the short test time compared to other methods, this assumption did not hold well for the epoxy material tested. The ramp rate chosen for the measurement will affect the amount of moisture lost from the sample. This has to be carefully chosen to minimize the moisture loss. These effects have to be accounted for in the CHS computation. The CHS value calculated will be significantly affected if these factors are high within the range of the measurement. This paper describes the investigation to minimize such effects in the measurement of CHS and attempts to account for them using computational methods. The CHS of an epoxy material was measured and its dependence on temperature and moisture concentration was determined.
Performance of Air Conditioners With Commercial Desuperheaters: A Green Energy Project as an Undergraduate Research
Authors: Yilmaz Emin , Nagchaudhuri Abhijit
Published: July 2010

The goal of the design project titled “Domestic Hot Water Heater Using Air Conditioner Waste Heat” was to introduce students to designing mechanical systems in the “ETME475-Mechanical Systems Design” course. Two students completed the design project in spring 2007. Some test runs were conducted with a commercial desuperheater to measure the efficiency of the unit and its effect on the Coefficient of Performance (COP) of the Heat Pump when the heat pump is operated in air conditioning (A/C) mode. Contrary to author’s expectations, results indicated that, COP values were reduced by about 22%. Measured efficiency of the desuperheater was about 18% [1]. The current project is an extension of the original project with the new National Instruments data acquisition board, a newly developed LabVIEW data acquisition program, and with a more realistic heat transfer loop. The study covers performance of the heat pump operating in A/C mode as well as in heating mode. Results indicate, depending on the water temperature in the desuperheater, heat pump COP dropped 6–17% in A/C mode and 8–38% in heating mode. Again depending on the average water temperature in the ECU, the ECU efficiencies ranged from 12% to 27% for cooling and 11% to 39% for heating.
Production of Synthetic Petroleum Fuel Through the Absorption of Atmospheric CO2
Authors: Pothier Stephen G. , Chichka David
Published: July 2010

This paper describes a theoretical device called a Petroleum Synthesizer, which absorbs the greenhouse gas carbon dioxide from the atmosphere and converts it into a synthetic petroleum fuel. The device has four parts: First, a CO2 Scrubber using sodium carbonate reversibly absorbs CO2 from the atmosphere. Simultaneously, a Hydrogen Generator separates water electrolytically to produce hydrogen (H2). Third, a Carbon Monoxide Generator mixes the H2 and the CO2 over a nickel catalyst, changing the constituents into carbon monoxide (CO) and water. Finally, the CO and additional H2 are combined in a cobalt-catalyst Fischer-Tropsch (F-T) Processor to produce gaseous and liquid petroleum products. Calculations show that one watt of electricity supplied for one year would allow the Synthesizer to create 0.420 kg of petroleum products, and absorb 1.314 kg of CO2 from the atmosphere. An acre of solar voltaic panels powering Synthesizers could produce 46,000 kg, or about 14,000 gallons, of petroleum products per acre per year, and absorb 140,000 kg of CO2. By contrast, an acre of corn produces less than 400 gallons of ethanol per year.
Scaled Experiments Evaluating Pulse Jet Mixing of Slurries
Authors: Bamberger Judith Ann , Meyer Perry A. , Enderlin Carl W. , Fort James A. , Wells Beric E. , Minette Michael J. , Burns Carolyn A. , Baer Ellen B. K. , Eakin David E. , Elmore Monte R. , Snyder Sandra F.
Published: July 2010

Pulse jet mixing (PJM) tests with noncohesive solids in Newtonian liquid were conducted at three geometric scales to support the design of mixing systems for the Hanford Waste Treatment and Immobilization Plant. The test data will be used to develop mixing models. The models predict the cloud height (the height to which solids will be lifted by the PJM action) and the critical suspension velocity (the minimum velocity needed to ensure all solids have been lifted from the floor), two parameters measured during the tests. From the cloud height estimate, the concentration of solids near the vessel floor and the minimum velocity predicted to lift solids can be calculated. The test objective was to observe the influence of vertically downward-directed jets on noncohesive solids in a series of scaled tanks with several bottom shapes. The test tanks and bottom shapes included small- and large-scale tanks with elliptical bottoms, a mid-scale tank with a spherical bottom, and a large-scale tank with a flanged and dished bottom. During testing, the downward-directed jets were operated in either a steady flow condition or a pulsed (periodic) flow condition. The mobilization of the solids resulting from the jets was evaluated based on: the motion/agitation of the particulate on the tank floor and the elevation the solids reach within the tank; the height the solids material reaches in the tank is referred to as the cloud height (HC).
Evaluating Concentration Profiles During Unsteady Mixing
Authors: Bamberger Judith Ann , Greenwood Margaret S. , Lawler Bruce D. , Sundaram S. K. , Baer Ellen B. K. , Hatchell Brian K. , Hopkins Derek F. , Kirihara Leslie J. , Pekour Mikhail S. , Sande Susan , Yu Xiao-Ying , Zuljevic Nino
Published: July 2010

Pulse jet mixing tests to suspend noncohesive solids in Newtonian liquid were conducted at three geometric scales. To understand the solids suspension process an ultrasonic concentration probe was used to measure the concentration of solids in the cloud during a pulse at various elevations and radial positions. The data are being analyzed to provide a model for predicting concentration as a function of elevation.
Analysis and Comparison of Performance of Two Small-Scale Trigeneration Plants: An ICE With a Liquid Desiccant Cooling System and a MGT With an Absorption Chiller
Authors: Badami Marco , Portoraro Armando , Ruscica Giuseppe
Published: July 2010

Two natural gas small-scale trigeneration plants are presented in the paper. Both plants are going to be started-up at the Politecnico di Torino (Turin, Italy) and are part of a new cogeneration and trigeneration systems laboratory, which is going to be setup and exploited for scientific and technical purposes. The first plant has 126/220/210 kW electrical, heating and cooling capacities, respectively, and is characterized by an innovative internal combustion engine that has been coupled to a liquid LiCl-water desiccant cooling system, which provides cooled and dehumidified air to a classroom building. The other plant has 100/145/98 kW electrical, heating and cooling capacities and is composed of a natural gas micro gas turbine, coupled to a LiBr-Water absorption chiller, which provides cooled water to the internal cooling grid at the Politecnico. The paper has the aim of comparing the performances of the two plants from an energetic and economic point of view; the Primary Energy Savings are calculated through different methodologies reported in literature for both installations, and the results are compared and discussed. A comparison of the economic performance offered by the two plants is also reported, together with a sensitivity analysis on the influence of subsidies foreseen by Italian Legislation on economic profitability.
Heat Transfer and Pressure Drop Through Rectangular Helical Ducts
Authors: Sleiti Ahmad K. , Naimaster Edward J.
Published: July 2010

Optimization of heat transfer and flow in a helical duct of rectangular cross-section used to cool the stators of electric machines is studied using computational fluid dynamics (CFD) techniques. Realizable turbulent model is used with water and oil as working fluids for two different designs (Spiral (S) and Reverse Annulus (RA) designs) and total of five configurations of the helical duct at small pitch size of 0.00254 m. The Reverse Annulus (RA) is a new design proposed by the author. Due to the curvature of the ducts, as fluid flows through curved tubes, a centrifugal force is generated. A secondary flow induced by the centrifugal force has significant ability to enhance the heat transfer rate. Results showed that the spiral design provides better heat transfer in terms of lower surface temperatures at the expense of higher pressure drop for the same flow rate of fluid.
A Mathematical Based Design Methodology for Crossflow Heat Exchangers
Authors: Dumas Antonio , Trancossi Michele
Published: July 2010

This paper presents a theoretical work, in order to apply well tested experimental correlations by Gnielinski to a lumped parameters analysis of cross-flow heat exchanger. It produces an effective set of equations which could be useful and effective in order to produce an accurate design of staggered and in line heat exchangers, but also heat pipes based exchangers. The presented method can help designer of heat exchangers to design and determinate performances of cross flow heat exchangers starting by the physical properties of a pipe (or heat pipe) and using geometrical parameters of the exchanger produces an effective evaluation of performances of the whole exchanger.
Experimental Research on Heat Transfer and Laminar Flow Through a Channel Filled With Porous Medium
Authors: Shokouhmand H. , Emami S. M. , Shajari G.
Published: July 2010

An experimental study was performed to investigate the heat transfer characteristics of the convection flow through a rectangular air duct with aspect ratio of 10 (a/b = 10) which is filled with metallic porous materials. All four walls of the duct are subjected to a constant and uniform heat flux. The Reynolds number based on the hydraulic diameter has been kept between 500–2000 in order to ensure the laminar flow through the duct. The effect of different parameters such as variable porosity and density of porous layers have been investigated. For different porous layers configuration, heat flux at the walls, wall temperatures and air mass flow rate has been measured and the Nusselt number has been calculated. The results are compared with the clear flow case where no porous material was used. it can be concluded that higher heat transfer rates can be achieved in porous media flow case at the expense of a reasonable pressure drop. Based on the experimental data new empirical correlations for both Nusselt number and friction factor have also been developed for such air duct, which gives a good agreement between predicted values and experimental values of Nusselt number and friction factor.
A Fuel-Spray Simulation Considering Fuel-Jet Breakup Near Fuel Injector and Composition of Air/Fuel Mixture
Authors: Ishii Eiji , Yasukawa Yoshihito , Sukegawa Yoshihiro , Yamada Hiroshi
Published: July 2010

To simulate multi-scale free surfaces in the fuel spray of an injector for automobile engine, we combined a liquid-film-breakup simulation and an air/fuel-mixture simulation. The liquid-film breakup near the injector outlet was simulated by using a particle method, and the air/fuel mixture after the liquid-film breakup was simulated by using a “discrete droplet model” (DDM). Distributions of droplet diameters and velocities, calculated in the liquid-film breakup simulation, were used as the injection condition of DDM. We applied our new method to simulate the spray from a collision fuel injector. The simulation results were verified by comparing them with measurements. The liquid-film breakup near the injector outlet and the behavior of the air/fuel mixture qualitatively agreed with the measurements. We found that out new method was useful to the fuel-spray simulation for automobile engines.
Flow Separation
Authors: Fakheri Ahmad
Published: July 2010

In thermal science courses, flow over curved objects, like cylinders or spheres are generally discussed qualitatively, followed by the presentation of numerical or experimental results for the drag coefficient, Nusselt number, and flow separation. Rarely, there is much discussion of how solutions are obtained. In this paper the flow separation is first introduced by solving the Falkner-Skan flow. The process for numerical solution of equations is presented to show that the flow separates at a plate angle of about −18°. Comparisons are drawn between this and flow over a cylinder. The non-similar boundary layer equations are then solved flow over a cylinder, using potential flow results for the velocity outside of the boundary layer. This solution shows that the flow separates at 103.5°, which is significantly more than the experimental value of 80°. Using a more realistic velocity for flow outside of the boundary layer, the numerical solution obtained predicts flow separation at an angle of 79°, which is close to the experimental results. All the solutions are obtained using spreadsheets that greatly simplify the analysis.
A Methodology for Developing Energy Process Step-Models for Manufacturing on a National Scale
Authors: Ozalp Nesrin
Published: July 2010

Manufacturing energy flows are characterized by two types of models: an energy process-step model and an energy end-use model. This paper provides a methodology for developing energy process-step models using federal database. Since energy end-use model provides the basis to scale energy process-step model, first, the concept of an energy end-use model is briefly described. Then, a concise methodology to construct the key part of the energy end-use model is given, namely, on-site steam and power generation model. Finally, a thorough methodology to develop energy process-step model showing energy inputs at each step of an industrial process is described by providing reconciliation with the energy end-use model results. An example methodology is provided for nitrogen, oxygen and argon production energy process-step models. Our approach to creating these models has been shown to be applicable to other energy intensive manufacturing industries. When used in conjunction with similar models for other years, these models can be used to identify the changes and trends in energy use.
Investigation on the Interactions Among Light, Material and Temperature Field in Transient Lens Effect
Authors: Doan Hong Duc , Fushinobu Kazuyoshi , Okazaki Ken
Published: July 2010

Recent advances in measurement techniques using the photo-thermal effect has draw more and more attention to the application in various fields. Especially, laser measurements are becoming increasingly important for the thermal design of electronic devices because these measurements can be applied to non-invasive and non-destructive measurement [1, 2]. We focus on the transient lens effect, which is a well-known photo-thermal phenomenon. As this effect is caused by the change of thermal properties or other physical properties, the measurements using this effect have the possibility to measure various materials information. This phenomenon has the optical property of a concave lens since the refractive index distribution on the optical axis is formed when the liquid is irradiated. One reason for the refractive index distribution in the liquid is the temperature distribution in the liquid when it is irradiated. So that, in this research we investigate the interaction between refractive index and temperature distribution on the Transient lens effect, in order to develop fluidic optical devices.
Experimental Investigation of a Turbulent Compressible Boundary Layer
Authors: Reedy Todd
Published: July 2010

A turbulent compressible boundary layer in a nominally Mach 4.2 flow was investigated experimentally. Pitot, wall-static pressure, total pressure and temperature measurements were utilized to determine Mach number, temperature, and velocity profiles within the boundary layer. An adverse pressure gradient was observed, resulting in non-uniform flow in the streamwise direction of the test section during development. Alterations were made to the tunnel top and bottom walls to account for the growing boundary layer displacement thickness, resulting in a much improved, uniform Mach number in the freestream and boundary layer. The existence of a slight adverse pressure gradient remained. Flow visualization was conducted via the Schlieren imaging technique. Experimental results were compared against turbulent compressible flow theory and were found to be in excellent agreement, based on an extension of the law-of-the-wall and law-of-the-wake. Velocity profiles and boundary layer thicknesses of the theoretical and experimental results aligned satisfactorily.
Total Temperature Measurements of Gaseous Flow at Micro-Tube Outlet: Cooled From the Wall
Authors: Yamamoto Takaharu , Hong Chungpyo , Asako Yutaka , Suzuki Koichi
Published: July 2010

This paper presents experimental results on heat transfer characteristics of gaseous flow in a micro-tube with constant wall temperature whose wall temperature is lower than the inlet temperature (cooled case). The experiment was performed for nitrogen gas flow through a micro-tube with 163.4 micro meters in diameter and 50 mm in length. The gas was heated at the inlet of the micro-tube to Tin = 315K, 335K and 355K. The wall temperature was maintained at 305K which was lower than the inlet temperature by circulating water around the micro-tube. The stagnation pressure was chosen in such a way that the exit Mach number ranges from 0.1 to 0.9. The outlet pressure was fixed at the atmospheric condition. The total temperature at the outlet, the inlet stagnation temperature, the mass flow rate, and the inlet pressure were measured. The numerical computations based on the aribitary-Langrangian-Eulerian (ALE) method were also performed for the same conditions of the experiment. The total and bulk temperature obtained by the present study are compared with those of the numerical cases and also compared with temperatures of the incompressible flow. The results have similar trends.
A Unified Approach for H∞ Complementary Sensitivity Design of PID Controllers Applied to a DC Motor With Communication Delay
Authors: Emami T. , Watkins J. M.
Published: July 2010

In this paper a graphical technique is introduced for finding all continuous-time and discrete-time proportional integral derivative (PID) controllers that satisfy the discrete-time H∞ complementary sensitivity constraint of an arbitrary order transfer function with time delay. These problems can be solved by finding all achievable PID controllers that simultaneously stabilize the closed-loop characteristic polynomial and satisfy constraints defined by a set of related complex polynomials. The key advantage of this procedure is that this method depends only on the frequency response of the system. If the plant transfer function is given, the procedure is still appropriate. The delta operator is used to describe the discrete-time controllers because it not only possesses numerical properties superior to the discrete-time shift operator, but also converges to the continuous-time controller as the sampling period approaches zero. A unified approach allows us to use the same procedure for discrete-time and continuous-time complementary sensitivity design of PID controllers. The method is demonstrated by using the experimental frequency response of a DC motor with communication delay for H∞ complementary sensitivity design of PID controllers.
Experimental Investigation of Area Ratio on Microjet Array Heat Transfer
Authors: Michna Gregory J. , Browne Eric A. , Peles Yoav , Jensen Michael K.
Published: July 2010

Electronics cooling is becoming increasingly difficult due to increasing power consumption and decreasing size of processor chips. Heat fluxes in processors and power electronics are quickly approaching levels that cannot be easily addressed by forced air convection over finned heat sinks. Jet impingement cooling offers high heat transfer coefficients and has been used effectively in conventional-scale applications such as turbine blade cooling and the quenching of metals. However, literature in the area of microjet arrays is scarce and has not studied arrays of large area ratios. Hence, the objective of this study is to experimentally assess the heat transfer performance of arrays of microjets. The microjet arrays were fabricated using MEMS processes in a clean room environment. The heat transfer performance of several arrays using deionized water as the working fluid was investigated. Inline and staggered array arrangements were investigated, and the area ratio (total area of the jets divided by the surface area) was varied between 0.036 and 0.35. Reynolds numbers defined by the jet diameter were in the range of 50 to 3,500. Heat fluxes greater than 1,000 W/cm2 were obtained at fluid inlet-to-surface temperature differences of less than 30 °C. Heat transfer performance improved as the area ratio was increased.
Economical Optimization of Integrated Cooling Tower by Solar Energy
Authors: Panjeshahi Mohammad Hassan , Ahmadi Lena , Gharaie Mona
Published: July 2010

Nowadays, the visible impact of releases to the ambient has become a matter of greater concern due to the awareness of environmental degradation and protection among the society. Therefore, the contribution of renewable energies as the free and clean sources can provide environment-friendly solutions. However, little attention has been paid to the practical applications of the renewables. Cooling towers are widely used in industries and commercial buildings to dissipate waste heat to the ambient environment. During unfavorable weather conditions, the exhaust of the wet cooling tower remixes with the cooler ambient air and as it cools down the excess moisture condenses in small fog droplets, creating visible plume. The generated plume sometime can extend up to few hundred meters and causes invisibility and darkness problem. In this study, solar energy is integrated into wet cooling tower to reduce the visible plume formation. In this method, optimum solar system is achieved taking into consideration the economical analysis. Also, the operational conditions of cooling tower at various environmental states have been incorporated in targeting the optimum solar system through different scenarios. Related coding in MATLAB version 7.1 is developed for computations.
Addressing Most of ABET Criterion 3 Issues First in an Early Design Class
Authors: Bannerot Richard
Published: July 2010

The Accreditation Board for Engineering and Technology (ABET) Criterion 3 requires that students attain an ability, knowledge and/or understanding in a variety of areas. Most engineering programs select the ABET Criterion 3 issues plus a few more as their Program Outcomes when defining their program, as have we. The faculty have identified at least three courses for each of our Program Outcomes in which to document assessment of student learning. The sophomore design class is responsible for assessing student learning related to seven of the eleven Criterion 3 issues plus the ME Program Criterion for designing and realizing a mechanical system. The paper will provide summaries of the assignments and examples of how the assessment is organized and conducted.
Gurtin-Type Quasi-Variational Principle for Large Deformation Elasto-Dynamics Based on Base Forces Theory
Authors: Liu Zongmin , Liang Lifu , Fan Tao , Song Haiyan
Published: July 2010

Considering that “gap function” is a nuisance term that contains both the stress and the quadratic function of displacement, it is difficult to establish Gurtin-type variational principles for large deformation elasto-dynamics. Luo En, Finlayson B. A. and Scriven L. established Gurtin-type variational principles by restricted variational idea. Based on base forces theory framework, the basic equations for large deformation elasto-dynamics are defined. Using the concept of base forces, Gurtin-type quasi-variational principle for large deformation elasto-dynamics can be established by variational integral method directly. When the base forces and the conjugate variable “displacement gradients” are taken as the basic unknowns, there is no “gap function” in the functional of Gurtin-type quasi-variational principle. Then quasi-stationary value conditions of Gurtin-type quasi-variational principle are derived. One of the quasi-stationary value conditions is the famous wave equation. Finally, some correlative problems are discussed.
Equations of Motion of a Ring-Like Robot With a Flexible Body and Creeping-Rolling Motion
Authors: Nejad A. H. , Alasty A.
Published: July 2010

The robots that can move on rough terrains are very important especially in Rescue operation, exploration, etc. In this research, a mechanism is introduced for a ring-like robot with a flexible body. This robot is moved by arms which are placed radially and have Reciprocating motion in this direction. By controlling the contraction and the extension of the arms which contact the ground, the robot will be forced to move which is called rolling-creeping motion. The robot is stable in stationary state; also the maximum angle which it can be stable is determined. Considering the speed of contracted arm is the input parameter, the speed of the extended arm for locomotion of the robot has been obtained from that. Not only the speed of mass center is accounted, but also the variation of the input parameter is computed for constant speed of the robot. So, dynamic analysis is illustrated by quasi-static stability assumption. Finally, the results of the motion simulation are shown to confirm equations.
Leading Indicators of Damage for Prognostication of Leadfree Electronics Subjected to Multiple Thermo-Mechanical Environments
Authors: Lall Pradeep , Vaidya Rahul , More Vikrant , Suhling Jeff , Goebel Kai
Published: July 2010

Electronic assemblies deployed in harsh environments may be subjected to multiple thermal environments during the use-life of the equipment. Often the equipment may not have any macro-indicators of damage such as cracks or delamination. Quantification of thermal environments during use-life is often not feasible because of the data-capture and storage requirements, and the overhead on core-system functionality. There is need for tools and techniques to quantify damage in deployed systems in absence of macro-indicators of damage without knowledge of prior stress history. The presented PHM framework is targeted towards high reliability applications such as avionic and space systems. In this paper, Sn3.0Ag0.5Cu alloy packages have been subjected to multiple thermal cycling environments including −55 to 125C and 0 to 100C. Assemblies investigated include area-array packages soldered on FR4 printed circuit cards. The methodology involves the use of condition monitoring devices, for gathering data on damage pre-cursors at periodic intervals. Damage-state interrogation technique has been developed based on the Levenberg-Marquardt Algorithm in conjunction with the microstructural damage evolution proxies. The presented technique is applicable to electronic assemblies which have been deployed on one thermal environment, then withdrawn from service and targeted for redeployment in a different thermal environment. Test cases have been presented to demonstrate the viability of the technique for assessment of prior damage, operational readiness and residual life for assemblies exposed to multiple thermo-mechanical environments. Prognosticated prior damage and the residual life show good correlation with experimental data, demonstrating the validity of the presented technique for multiple thermo-mechanical environments.
Modified PD Control of Rotary Inverted Pendulum
Authors: Sepehry Naserodin , Shamshirsaz Mahnaz
Published: July 2010

The inverted pendulum, a classical mechatronic application, exists in many different forms. In despite that many works have been done to balance the pendulum link on end of this device using feedback control but few studies have been developed to control this rotary inverted pendulum using PD controller. In classical methods, using PD, PI or PID control, difficulties appear due to one of the coefficients becomes zero in closed loop transfer function denominator and consequently the system becomes unstable. In this study, an arbitrary pole is placed in order to create a break point in root locus, so by this way a PD controller can be designed for this new system. Also, disturbance rejection has been investigated by state space method in this paper. The results of this modified PD controller are compared with full state feedback control and optimal control, so the method used in this study has been validated.
Investigation of Indoor Environment for a Data Center
Authors: Li Lingcang , Liu Yanlei , Wang Xiuling , Nnanna A. G. Agwu
Published: July 2010

Special indoor air environment requirements are needed for the data center, such as ambient temperature, airflow pattern, relative humidity and ozone concentration to maintain the reliability of a computer system. In this paper, a numerical simulation based on 3-D Finite Volume Method has been conducted for a data center at Purdue University Calumet. The purpose of the simulation is to find out the most effective and low-cost air condition system. Results for temperature, relative humidity distributions as well as velocity patterns are presented. Mesh independent studies are performed. Numerical results are validated by experimental data. Suggestions are given based on the simulation results for improving the indoor environment of the data center.
High Efficiency Design of High Pressure Radial Fan Spiraled Casings Used for Biogas Transport
Authors: Miclea Mihai , Epple Philipp , Schmidt Harald , Delgado Antonio , Russwurm Hans
Published: July 2010

The use of low speed radial impellers is very common for industrial fans and blowers. Some of the applications include fans designed for the transport of biogas in biogas plants. The design process of fans is almost always direct, based on existing impeller series and available experimental data as stated recently in [1]. This paper presents the design results and optimization of low speed/high pressure radial impellers with spiraled casings used for such an application through a combined inverse approach. The aim was to design high efficiency impeller-casing systems for a specified operating point or a specified operating flow range, as well as to adjust the slope of the pressure-flow rate characteristic of the system for the desired high pressure specifications. The design point, and hence the maximum efficiency of these blowers has been set by the manufacturer at very small flow rates implying an iterative design approach of both impeller and casings. Here will be presented how the geometrical design parameters are influencing the performances of such fans. Several casings configurations with and without vaneless diffusers, different tongue radii, design flow rates or casing-impeller height ratios were investigated. They were numerically simulated with a commercial Navier-Stokes CFD solver (ANSYS CFX V11.0) and by evaluating their results an understanding of the inside flow physics could be achieved. To properly filter and analyze the investigated design results of the casings, a new performance parameter was successfully implemented and validated. This performance parameter will be called the casing (or volute) efficiency, and will be explained later in this paper. Results are showing the influences of several geometrical and construction parameters of casings and some backward (reversed) conclusions on impeller design suited to operate in such systems. Finally conclusions are presented, analyzing the suited casing geometries for reaching the desired performances as well as the advantages of this combined analytical and numerical method suited to perform a coupled design of high efficiency spiral casings for radial impellers.
Design Optimisation of Finned Channel
Authors: Seakher K. M. C. , Prakash Kumar L. S. S. , Kali Prasad K. S. R. , Manasa K. H. , Siva Kumar A.
Published: July 2010

A finned channel has a higher heat transfer coefficient compared to a smooth channel and the increase in this fin height enhances the heat transfer. But this heat transfer enhancement is accompanied by an increase in pressure drop for a series of fins. This requires an increase in pumping power requirement, indicating that there exists an optimum design or length of the fin at which the heat dissipation is maximum. The objective of this paper is to observe the variation of heat transfer with varying sizes of fins. The effect of fin dimensions on heat transfer can be clearly seen in its performance, which is discussed in the paper. The results are obtained by analytical analysis, and some illustrations are dealt with in the paper, which clearly determine the importance of this factor of optimal fin length.
Numerical Analysis of Surface Oscillation of a Levitated Droplet Using Particle Method
Authors: Dupac Mihai , Beale David G.
Published: July 2010

In this paper, the effect of the surface oscillations of a levitated droplet subject to electromagnetic and external forces, and modeled as a 3D mesh-free fluid particles system, is considered. The droplet was analyzed in a force field, which was derived from the magnetic field produced by the coil. The electromagnetic force was continuously updated with the shape and position change. To describe the fluid motion, the Navier-Stokes equations are discretized using the Moving Particle Semi-implicit (MPS) method. A numerical model based on MPS method was developed, the equations of motion were solved, the free surface of the droplet was approximated, the interface reconstructed and the oscillations frequency spectra analyzed. Two weight functions are considered and their performance compared in order to to improve the stability of MPS method.
Vitamin B Complex and Bioheat Transfer Projects: 2008 Summer Research Experiences for Teachers at Milwaukee School of Engineering
Authors: Kumpaty Subha , Foster Asha , Hutson Alex , Paliwal Vipin
Published: July 2010

This paper describes the summer research experiences of a high-school chemistry and biology teacher and a middle-school science teacher at the Milwaukee School of Engineering (MSOE). The first project involved researching B Complex Vitamins at MSOE’s Center for Biomolecular Modeling, developing molecular models using rapid prototyping technology (Z Corp 3D Printer) and creating curriculum modules for teaching the role of B Complex Vitamins to chemistry students in public high schools. A Javascript/HTML for interactive and dynamic presentation for understanding of thiamine (Vitamin B1) via web was written and implemented with Jmol software. A visual inspection of the family of Vitamin B Complex created and the curriculum modules developed during this project provide exciting and effective learning avenues for students in biology and chemistry classrooms. The second project dealt with the study of bioheat transfer and its simulation using MATLAB, and creation of a curriculum module that illustrates heat transfer principles reinforced by implementing the simulation. The teachers enjoyed the interaction with their advisors and the positive environment for their professional development. Details of their projects and experiences along with the evaluation of the program are presented in this paper. The teachers were pleased to be involved in connecting physics, biology, engineering and math into real projects that will motivate the students in their classes to pursue careers in STEM fields.
Analysis and Cost Estimation of a Total Site Using R-Curve
Authors: Karimkashi Sh. , Amidpour M.
Published: July 2010

In large processing sites the cost of fuel and power can be very significant and better management of the utility system can lead to significant cost savings. The R-curve is an analysis tool that provides guidelines for the cogeneration efficiency for a given site power-to-heat ratio demand of an ideal utility system. In this paper, the actual R-curve is combined with another graphical tool, representing the cost of cogeneration potential of a site. In fact in each case, actual R-curve is constructed and then another curve of ‘R-ratio vs. TAC’ is constructed to demonstrate the cost of each point of the R-Curve. Finally showing the results obtained for a case study, it is suggested to change sizes of the turbines in the utility system to improve the R-curve and also decrease the TAC for the same R-ratios. These changes are almost dependent to the case being studied.
Robust Impedance Control of a Teleoperation System With Friction Compensation Under Time Delay
Authors: Monemian Esfahani A. , Rezaei S. M. , Zareinejad M.
Published: July 2010

Friction forces in the robot joints insert nonlinearity in the dynamic and make errors in tracking. In this paper a new impedance control for the master is proposed to achieve force tracking. In addition, an impedance control for slave combined with sliding mode, which is based on perturbation estimation, is anticipated to reach position tracking. Friction compensators typically include a friction observer that provides a cancellation term in order to be added to the control input. Estimating and compensating the friction and other uncertainties will change the nonlinear equation to a linear one. The stability of entire system under time delay is guaranteed by Llewellyn’s absolute stability criterion. Performance of the proposed controllers is investigated through experiments.
Effect of Shield-Can Design on Dynamic Responses of PCB Under Board Level Drop Impact
Authors: Yu Da , Kwak Jae B. , Park Seungbae , Chung Soonwan , Yoon Ji-Young
Published: July 2010

When a handheld device is subjected to a drop impact, the out-of-plane deformation of printed circuit board (PCB) is a major concern to manufacturers as it is directly proportional to the stress which causes failure for the solder joints. The shield-can attached to the PCB can provide additional mechanical strength and minimize the out-of-plane deformation. In this work, board level drop test is conducted with instrumentation following the Joint Electron Device Engineering Council (JEDEC) test standards. A non-contact full field optical measurement technique, Digital Image Correlation (DIC), is applied to monitor and document the dynamic responses of PCB during the drop test. Different shield-can type varying in shape and size are attached to the PCB through frame or clip type connection. The effects of these two connecting methods, as well as the shape and size of shield-can, on the dynamic responses of PCB are analyzed experimentally. Along with board level drop experiments, a detailed 3D FEA model has been developed to verify and analyze the dynamic responses of PCB using ANSYS/LS-DYNATM. Several simulations have been performed to verify experimental results. Different contact techniques, such as Nodes merge and Tied Nodes to Surface (TDNS) contact have been applied as boundary conditions to connect shield-can with PCB and a proper representation of connection is found in the simulation.
Improving the Performance of Cooling Water Systems Using Exergy Analysis: A Novel Approach
Authors: Panjeshahi Mohammad Hassan , Gharaie Mona , Ahmadi Lena
Published: July 2010

Circulating cooling water systems almost serve all the operations of industrial plants where there is requirement of an external heat sink for heat removal and temperature control. Research on cooling systems focused on the energy analysis of individual components, cooling tower and heat exchanger network. However, the energy concept, alone is insufficient to describe the energy efficiency of the whole system. In this study, the exergy analysis is applied to evaluate the performance of the circulating cooling water system. To achieve this objective, the exergy destruction of the cooling tower and heat exchanger network in terms of different operational conditions are investigated. The results indicated that the exergy destruction in the cooling tower is increased by increasing the cooling tower inlet temperature; whereas the exergy destruction of the heat exchanger network decreases. Therefore, the problem of cooling water system for performance evaluation becomes an optimisation problem to search for the minimum exergetic destruction. Additionally, the second law efficiency of the cooling tower and water network is studied through the exergetic analysis.