bluuebunny/crossref_metadata_2025 huggingface dataset:
The Interest of Mechanical Engineering Students in the Grand Challenges for Engineering in the 21st Century
Authors: Hailey Christine , Drysdale Michael , Householder Daniel
Published: August 2012

In 2008, the National Academy of Engineering (NAE) announced 14 Grand Challenges for Engineering in the 21st Century, a set of exceptionally complex problems associated with national security, quality of life, and a sustainable future. Understanding the extent to which engineering students are interested in these complex problems and the extent to which they feel confident that they can contribute to the solution of these problems could serve as a starting point to foster engagement with the Grand Challenges. This paper presents results from a survey of mechanical engineering (ME) students’ interest in the NAE Grand Challenges and their confidence in their ability to contribute to resolutions of the Challenges. Seventy-six sophomore mechanical engineering majors completed the survey composed of 36 examples of problems described within the NAE Challenge report. Survey results show a strong relationship between students’ interest and their confidence in meeting a challenge. Six students participated in a semi-structured interview regarding their experience with and knowledge of the Challenges. Interview results indicated the students had few course-related experiences that exposed them to the Challenges. Results of this study can contribute to a broader conversation among ME educators about ways to integrate the NAE Grand Challenges in undergraduate engineering education.
Studies of the Effect of Heat Treatment on Hardness and Creep Behavior of a Modified 9Cr-1Mo Steel
Authors: Wuthrich Z. , Shrestha T. , Charit I. , Rink K. , Basirat M. , Potirniche G. P.
Published: August 2012

In this study, heat treatment was carried out on modified 9Cr-1Mo steel specimens to determine the microstructural evolution for various normalizing temperature/time and tempering temperature/time combinations. Normalization was carried out in the temperature range of 1020–1100°C and time range of 2–8 hours, while tempering was performed in the temperature range of 690–790°C and time range of 2–20 hours. Optical microscopy was then used to visualize and chronicle the microstructural characteristics at varying levels of heat treatment. Vickers micro-hardness measurements were performed on each sample to obtain hardness values as a function of normalizing and tempering temperature/time. Creep tests have also been performed on as-received and welded specimens of modified 9Cr-1Mo steel, in the temperature range of 500–700°C and stress range of 50–200 MPa. Microstructural analysis was carried out on the specimens before and after creep deformation using both scanning and transmission electron microscopy. The microstructural evolution during the heat treatment and creep tests provided useful information to understand and characterize the creep deformation mechanisms of modified 9Cr-1Mo steel.
Noise Influenced Responses of Elastic Cantilevers With Nonlinear Tip Force Interactions
Authors: Chakraborty Ishita , Balachandran Balakumar
Published: August 2012

In this article, the effects of noise on a base-excited cantilever structure with nonlinear tip force interactions are studied by using experimental, numerical, and analytical methods. The focus of the study is on the enhancement of the cantilever response, when Gaussian white noise is added to the harmonic base input. The experimental arrangement consists of a base-excited elastic cantilever with a magnet attached to its free end. An attractive force is generated at the cantilever tip magnet through another magnet of opposite polarity, which is fixed to a translatory stage. The second magnet is covered by a thin compliant material, with which the tip magnet makes intermittent contact when the cantilever is subjected to a base excitation. For a purely harmonic excitation, it is observed that the tip magnet of the cantilever sticks to the base magnet due to the attractive force. Starting from a situation where the cantilever tip is sticking to the surface, band-limited white Gaussian noise is added to the excitation and the strength of noise is gradually increased. The cantilever tip resumes its periodic motion when the strength of added noise reaches a sufficient signal to noise ratio. This phenomenon is explored by using a reduced-order numerical model and an analytical framework involving the application of a moment-evolution approximation derived from the associated Fokker Planck equation for the system. Since the macro-scale experimental system qualitatively replicates the micro-scale attractive-repulsive force interaction experienced by an atomic force microscope cantilever operated in tapping mode, this study sheds light on the possible use of white noise to control the sticking of such micro-scale cantilevers with sample surfaces.
Intelligent Laundry Sorting System for Rest Homes
Authors: Davies Rose , Brazendale Lindsay
Published: August 2012

Radio-frequency identification (RFID) and mechatronic technology has been applied to a laundry sorting system which can potentially be used by rest homes in the future to reduce the labour intensity of care givers, to increase the efficiency of laundry sorting, and to reduce the chance of garments being lost. A laboratory laundry identifying and sorting conveyor belt has been built. Several different types of RFID labels/tags have been considered and tested. A type of small RFID laundry tag, suitable for the laundry sorting conditions of a rest home, has been selected. The laundry tags have undergone endurance testing under actual washing and drying conditions with typical commercial laundry chemical products used in rest homes. There was a major challenge using commercial RFID tags in the proposed intelligent laundry sorting system due limitations in their antenna and signal receiving systems. A strategy to coordinate the orientations of the tags, range of the antenna, and the amplification of signal receiving units has been investigated. Several antenna designs to improve the identification rate have been tested and analysed for the selected small laundry tags, since the tag-receiver system has to work beyond the recommended range. A programme for signal detection and processing has been produced. The programme has taken into consideration the speed of the conveyor belt, antenna receiving range and the time required to process signals. It works with satisfactory precision at a satisfactory speed. A sorting strategy for implementation after laundry garment identification has been investigated. This strategy considers aspects of simplicity, multifunction and compactness of mechanical structure. A virtual sorting system has been produced to test the principles of the sorting strategy and the antenna design. The results of these tests will help us to move to the next stage, the design of a prototype laundry sorting system.
CFD Analyses of the Mixing Characteristics in Bubble Columns and Airlift Reactors
Authors: Studley Allison , Battaglia Francine
Published: August 2012

The mixing characteristics in bubble columns and airlift reactors are analyzed using computational fluid dynamics. In the simulations, an Eulerian-Eulerian approach was used to model air as the dispersed phase within a continuous phase of water using the commercial software FLUENT. The Schiller-Naumann drag model was employed along with virtual mass and the standard k–ε turbulence model. An effective bubble diameter was specified for each case studied and depended on the inlet gas velocity specified. The predicted flow field in the airlift geometry showed a regular oscillation of the gas flow due to flow recirculating from the downcomer and connectors, whereas the bubble column oscillations were random and resulted in flow moving through the center of the column. The profiles of gas holdup, gas velocity, and liquid velocity versus column width showed that the airlift reactor flow is asymmetric and the profile shape varied along the height of the column. The bubble column flow became independent of height after 20 cm above the inlet because there was less mixing than the airlift reactor. It was shown that the airlift reactor increased the mixing of the gas-liquid flow due to the addition of the downcomer. The airlift reactor showed less gas holdup in the riser than the bubble column but its velocity and gas holdup never became independent of column diameter like in the bubble column. The gas and liquid flow field showed increased mixing with increasing inlet velocity.
Analysis of Ultrasonic Machining Using Monte Carlo Simulation
Authors: Sahay Chittaranjan , Ghosh Suhash , Kammila Hari Kiran
Published: August 2012

Proper selection of manufacturing conditions is one of the most important aspects in Ultrasonic Machining process, as these conditions determine the Material Removal Rate (MRR). In this work, two very popular mathematical models proposed by Miller and Shaw have been investigated using Monte Carlo simulation based Crystal Ball analysis tool. Effects of abrasive particle size, particle concentration, amplitude of tool vibration, tool radius and depth of hole on MRR have been analyzed for both models. Miller’s model indicates a strong positive relationship between abrasive grain size, concentration and MRR. Contrary to the literature search on experimental data, Shaw’s mathematical model indicates a negative relationship between MRR and grain size, and a very weak relationship between MRR and concentration. No definite relationship could be established between either tool radius and MRR or amplitude and MRR. A negative relationship between depth of hole and MRR was obtained for Shaw’s model.
Numerical Simulation of the Flow Boiling Heat Transfer Performance of R134a in a Microchannel Evaporator With Louvered Fins
Authors: Gossard Justin J. , Sommers Andrew D.
Published: August 2012

The need for more compact and more efficient heat exchangers in the aerospace, automotive, and HVAC&R industries has led to the development of heat exchangers that utilize minichannel or microchannel tubes coupled with louvered fins. Minichannel and microchannel heat exchangers exhibit enhanced heat transfer with a minimal increase in pressure drop over conventional round tube, plain fin heat exchangers often with a significant reduction in the required refrigeration charge and overall heat exchanger size. This paper presents the development and validation of a finite volume, steady-state evaporator model to be used as an aid in heat exchanger design and analysis. The model focuses on evaporator geometries that include minichannel and microchannel tubes with louvered fins and headers. Multiple published correlations provide the user with options for calculating the air-side and refrigerant-side heat transfer and pressure drops within the control volume. Once the model was validated, it was then briefly used to study the effects of maldistribution of refrigerant within the inlet headers on the cooling capacity and refrigerant side pressure drop.
Early-Stage Evolution of Electrons Emitted From Metal Target Surface During Ultrashort Laser Ablation in Vacuum
Authors: Tao Sha , Wu Benxin
Published: August 2012

The early-stage evolution of electrons emitted from a metal target surface during ultrashort laser ablation in vacuum has been studied using a physics-based model. This kind of research work has been rarely reported in literature. In the model, the target heat transfer process is simulated by solving the two-temperature heat transfer equations, based on which the photoemission and thermionic emission of electrons from the target surface are calculated. The early-stage evolution of emitted electrons is described by solving the electron mass, momentum, and energy conservation equations, coupled with the Poisson’s equation that governs the developed electric field. The study shows that a relatively very high free electron density can be developed near the target surface, and the front of emitted electrons propagates very fast into the vacuum. The developed electric field strongly affects the evolution of emitted electrons. Using the physics-based model, the temporal variation and the spatial distribution of the emitted electron number density, and velocity will be studied and discussed. The early-stage evolution of the emitted electrons may affect the possible subsequent hydrodynamic motion in the target, and the resulted plasma formation and material removal (laser ablation) processes. Therefore, this study provides very useful information for the understanding of ultrashort laser-material interaction, laser-induced plasma, laser ablation (machining), and other relevant processes.
Fluid Induced Vibration in the Liquid-Filled Hydraulic Circuit of Passive Interconnected Suspensions
Authors: Zhao Jing , Zhang Nong , Ji Jinchen
Published: August 2012

The fluid flow inside the liquid-filled pipe-guided hydraulic circuit of a Hydraulically Interconnected Suspension (HIS) often lead to vibrations of the whole pipeline and associated structures and hence become a source of structural noise. This paper presents an investigation of fluid induced vibration into the pipeline. The one-dimensional wave theory is employed to formulate the equations of motions that govern the dynamics of the fluid-structural system. Axial and one plane of lateral vibrations as well as the effects of shear deformation on the lateral vibration of the pipe are considered. The transfer matrix method (TMM) is applied to determine the steady state response of the fluid-structural system, which consists of various pipe sections, hose sections, damper valves, accumulators, supports and joints that connect separate pipe branches. The overall system transfer matrix including fluid and pipe mechanics is obtained by combining with field transfer matrices representing the motion of single pipe sections and hose sections and various point transfer matrices that describe specified junction conditions. The developed model of the hydraulic system is examined through simulations and laboratory based rig tests. The simulation results show the hydraulic components have apparent impact on the dynamics of combined pipe structural and fluid system. The experiments performed on a hydraulic circuit and the measured steady state responses of the circuit are compared with those obtained from the simulations. It is found that the developed model of the hydraulic system including the coupling with boundaries has a reasonable accuracy in the frequency range of interest.
Energy and Emissions Assessment in Pumping Water Distribution Systems: Case Study—Colorado River–Tijuana Aqueduct
Authors: Gil Samaniego Ramos Margarita , Campbell Rami´rez He´ctor Enrique
Published: August 2012

The northwestern portion of the Mexican territory has a semiarid climate with scarce rains and no reliable water supply sources. The cities of Tijuana, Tecate and Rosarito, Baja California, Mexico, are located within this zone and depend on the Ri´o Colorado–Tijuana Aqueduct to fulfill approximately 90% of its water demand. This large hydraulic facility is 147 km long and elevates 4.0 m3/s of water at a height of 1,060 m. It is composed of 6 pumping stations with a total installed motor capacity of 79,500 hp. At this time the capacity of the aqueduct is being increased to 5.33 m3/s by means of installing an additional pump to each pumping station and a 54″ parallel line. The motor capacity increase will be of 26,500 hp. In 2009, its electricity consumption was of 433,589 MWh at a cost of $29,494,630 USD. Emissions to the atmosphere associated to this electricity consumption were calculated to be: 73 tonnes of SO2, 73 tonnes of NOx and 116,467 tonnes of CO2. This paper presents the methodology used to evaluate the potential savings of electricity and emissions and recommends alternatives to decrease its current energy consumption. Results obtained show that 35,949 MWH at a cost of $2,762,300 USD can be saved annually if the equipment performance were at its optimal efficiency. Emissions to the atmosphere avoided would be of 9,656 tonnes of CO2, 6 tonnes of SO2 and 17 tonnes of NOx.
Optimal Angle of Inclination for Fixed Solar Panels/Collectors
Authors: So¨zen Mehmet , Griffin Jacob
Published: August 2012

In the use of solar energy as a source of renewable energy a practical question is commonly encountered. “What is the optimal angle of inclination for fixed solar panels?” This is applicable for both arrays of solar photovoltaic (PV) panels as well as for flat plate solar collectors. It is quite common practice to use a couple of rules of thumb that state the following: (a) the panels/collectors should be facing south (for the northern hemisphere locations), and (b) the optimal angle of inclination will be in the range of the location latitude ± 15°. In this paper we discuss a computer program developed to verify (b) for south facing fixed solar panels/collectors. The program developed can generate theoretical solar irradiation that will be available for a given location in the northern hemisphere on a clear day taking into account the attenuation effects in the atmosphere by incorporating the concept of air mass. It can also be used to retrieve solar irradiation data from well established databases such as the National Solar Radiation Data Base (NSRDB) [1–2] accessible via the National Renewable Energy Laboratory (NREL). Both approaches have been tested and weekly, monthly and annual optimal angles of inclination have been generated for selected locations. This paper discusses the details of the algorithm and code developed and the results obtained. How this program is going to be used in an undergraduate course titled “Alternative Energy Systems and Applications” are also discussed.
Architectural Proposals for Electric Vehicle Design
Authors: Kulkarni Ambarish , Kapoor Ajay , Ektesabi Mehran , Lovatt Howard
Published: August 2012

Due to global warming and depletion of fossil fuels, alternative sustainable fuel technology is essential. As a consequence of this need, many automotive original equipment manufacturers have started manufacturing electric vehicles (EVs) as sustainable, zero-emission solution. This paper evaluates different architectures for EV design to establish a preferred architecture. A detailed literature study is outlined to evaluate production and concept proposals of many original equipment manufacturers, student projects, and autonomous electric cars. The different architectural aspects of these designs, such as mechanical and electrical technologies, are discussed. Starting with initial schematics, a theoretical model is developed for each of the EV drive train architectures. The study uses advanced modeling techniques to compare these architectures. Different drive train architectures are compared in the contexts of functionality, operation, manufacturability, and modularity. The preferred architecture was developed using advanced tools such as virtual modeling to establish operational sequences for the components that make up an EV. In addition, product data management software was used as management tool to document changes during the architecture’s development. Recommendations and discussions on a selection of vehicle architectures are detailed along with those for a preferred architecture.
Substrate Effects on the Thermal Conductivity of Single Layer Supported Graphene
Authors: Wei Z. , Dames C. , Chen Y.
Published: August 2012

A non-equilibrium molecular dynamics model is developed to calculate the thermal conductivity of single layer graphene supported on silicon dioxide. We use the Tersoff potential to describe the carbon-carbon interactions within graphene, and a Lennard-Jones (LJ) potential to describe the interactions between graphene and silicon dioxide. To overcome possible artifacts of thermal expansion, the model avoids using any periodic or fixed boundary conditions for the graphene flake. For both smooth and rough substrates, the simulations show that increasing the LJ coupling strength between graphene and substrate can reduce the in-plane thermal conductivity of graphene. We also investigated the effects of roughness. The simulations show that the thermal conductivity is sensitive to the roughness only when the coupling is large. These results indicate how the thermal properties of graphene may be modified by adjusting the coupling and roughness of the substrate.
Numerical Analysis of Nanofluids in Heat Pipe
Authors: Singh Pawan K. , Ahmed Nouman Zahoor , Ali Mohamed Ibrahim , Shatilla Youssef
Published: August 2012

The numerical analysis of nanofluids in heat pipe is investigated using CFD, computational fluid dynamics, software modeling, FLUENT. The modeling was completed for base fluids and validated against earlier study. The alumina-water nanofluids are used for the investigation due to availability of huge literature. The thermal conductivity and viscosity are evaluated on the basis of literature and used in the study. For the other thermo-physical properties such as density and specific heat, mass based mixture model approach has been used. To see the concentration effect of nanofluids, mixtures with volume fraction of 1, 2, 3 and 5% are considered. The nanofluids mixture assumed to be homogeneous fluid flow in this simulation. The inlet velocity boundary condition, BC, is given by two approaches, mass flow arte and volume flow rate. The results showed that the nanofluids performance is similar to the base fluids while inlet BC is constant volume flow rate. On the other hand, nanofluids enhanced the performance over the base fluid while constant mass flow rate BC is used.
Measurement and Prediction of Undisturbed Underground Temperature Distribution
Authors: Cui Wenzhi , Liao Quan , Chang Guiqin , Chen Guanghai , Peng Qingyuan , Jen Tien-Chien
Published: August 2012

The underground temperature distribution and variation are important for the development and utilization of shallow geothermal energy and underground space. In this paper, a remote ground temperature monitoring system was established in Chongqing, located in southwest China and the ground temperature distribution and its variation with seasons of the 100m underground depth was measured from June 2010 to June 2011. The results show that, in the typical geo-structure of Chongqing, the variational ground temperature zone is from 0m to 10m, where the ground temperature is strongly affected by the change of ambient temperature. Below 11m depth, the ground temperature does not change with seasons, i.e., it is the constant ground temperature zone. In the constant temperature zone below 40 meter depth, the geothermal gradient is about 0.02°C/m. Baggs’s empirical formula was applied to predict the ground temperature distribution history at different ground depths. The results show a good agreement with the measured data.
In-Situ Thermal Response Test for Ground Source Heat Pump Application
Authors: Cui Wenzhi , Liao Quan , Chang Guiqin , Peng Qingyuan , Jen Tien-Chien
Published: August 2012

The design and performance optimization of ground source heat pump (GSHP) systems need the exact thermal properties of the soil, such as ground thermal conductivity and capacity, and the borehole thermal resistance of borehole heat exchanger (BHE). In-situ thermal response test (TRT) is the most widely used method to determine the overall thermal physical properties of the geological structure around the borehole. A TRT experimental apparatus has been developed and thermal response test was performed in Chongqing, southwest China. Both single-U and double-U borehole heat exchangers are studied in this work. The test duration is about 70 hours. Data direct fitting and parameter estimate method are both used to determine the soil thermal conductivity and the borehole thermal resistance. The results showed that the average ground thermal conductivity of the test region for single U and double U BHE conditions are 2.55 and 2.51 Wm−1K−1, and borehole thermal resistance are 0.116 and 0.066 mKW−1, respectively.
Optimization of Pigmented Coatings for Concentrating Solar Thermal Applications
Authors: Yalcin Refet A. , Ertu¨rk Hakan
Published: August 2012

Spectrally selective coatings are used in absorbers of solar collectors to maximize efficiency of solar thermal energy systems. Desired coating should have high absorptance at solar wavelengths and low emittance at the wavelengths where absorber emits heat. This study focuses on pigmented coatings that consist of a binder and uniformly distributed nano-particles known as pigments that exhibit the desired spectrally selective behavior. Radiative behavior of coatings depend on coating thickness, pigment size, concentration, and the optical properties of binder and pigment materials. In order to understand the effect of these parameters, a radiative model of the pigmented coatings is developed using Lorentz-Mie theory in conjunction with Hartel theory to incorporate the multiple scattering effects. Through the solution of the radiative transfer equation by the four flux method, spectral emittance is predicted. Design of such a coating is formulated as an inverse problem of estimating design variables yielding the desired spectral emittance of the ideal coating. The nonlinear problem is solved by optimization applying two algorithms for the solution. While both algorithms are capable of providing the same solution, the convergence of Quasi Newton method is found to be superior to that of Nelder Mead simplex algorithm.
Effects of Externally Applied Electric Field on the Electric Double Layer Formed in an Electrolyte Layer and its Contribution Towards Joule Heating
Authors: Sharma Neeraj , Diaz Gerardo , Leal-Quiros Edbertho
Published: August 2012

Joule heating of liquid films in the presence of an externally applied electric field is influenced by the formation of the electric double layer. The thickness and charge distribution inside the electric double layer determine the extent of interaction of the charge in the electric double layer with the externally applied electric field and the Joule heating of the electrolyte layer. For this reason, the effects of externally applied electric field (both parallel and along the normal to the surface) on the electric double layer are being studied in the present paper. In the absence of the externally applied electric field, the distribution of the electric potential in the double layer is given by Poisson equation. Assuming Boltzmann distribution for the ionic concentration in the double layer, one arrives at Poisson-Boltzmann equation for the electric potential distribution. The externally applied electric field changes this electric potential distribution. Hence, the contribution of the externally applied electric field is studied by including it in the Poisson-Boltzmann equation.
Enhanced Air-Gap Control for High-Speed Plasmonic Lithography Using Solid Immersion Lens With Sharp-Ridge Nanoaperture
Authors: Hwang Hyunwoo , Lee Won-Sup , Park No-Cheol , Yang Hyunseok , Park Young-Pil , Park Kyoung-Su
Published: August 2012

Recently, plasmonic nanolithography is studied by many researchers (1, 2 and 3). This presented a low-cost and high-throughput approach to maskless nanolithography technique that uses a metallic sharp-ridge nanoaperture with a high strong nanometer-sized optical spot induced by surface plasmon resonance. However, these nanometer-scale spots generated by metallic nanoapertures are formed in only the near-field region, which makes it very difficult to pattern above the photoresist surface at high-speeds.
Development of an Artificial Muscle Using PVC Gel
Authors: Hashimoto Minoru
Published: August 2012

A poly vinyl chloride (PVC) gel actuator shows great potential for use as an artificial muscle because of such positive characteristics as movement in the air, large deformation, and being light in weight. A bending type actuator using PVC gel was studied previously. In order to construct an artificial muscle it is necessary to compose an actuator which has the characteristics of contraction type deformation. In the present paper we propose an electrode arrangement for a contraction type actuator using PVC gel. Also, we investigate the characteristics of the proposed actuator experimentally and show the effectiveness of the actuator as an artificial muscle. The experimental results showed that the contraction strain of the actuator was about 14%, the response rate was 7Hz, and the output stress was 4kPa. In order to apply the artificial muscle as a control element, we build a linear mathematical model of the electronic and mechanical characteristics. Based on the mathematical model, we design a control law of the PVC gel actuator. The control law is applied to the position control of the artificial muscle experimentally. The experimental results showed a good agreement with the simulated results using the mathematical model and an excellent performance in position control.
Upwind Solutions for Two-Phase Flow Problems Using a Hyperbolic Two-Fluid Model
Authors: Chung Moon-Sun , Jung Youn-Gyu , Yi Sung-Jae
Published: August 2012

This study discusses on the implementation of an upwind method for a new 2-dimensional 2-fluid model including the surface tension effect in the momentum equations. This model consists of a complete set of 8 equations including 2-mass, 4-momentum, and 2-internal energy conservation equations having all real eigenvalues. Based on this equation system with upwind numerical method, the present authors first make a pilot 2-dimensional code and then solve some benchmark problems to verify whether this model and numerical method is able to properly solve some fundamental one-dimensional two-phase flow problems or not.
Comparison Between Feed-Forward Back-Propagation and Radial Basis Functions Networks for Roughness Modeling in Face-Milling of Aluminum
Authors: Perez Carlos , Calderon Juan De Dios
Published: August 2012

The technology of the cutting process has evolved substantially in terms of materials, tools and machines; however it is a necessity to develop models for control and optimization of the cutting processes because nowadays industry relies mainly on empirical data and heuristic solutions provided by shop-floor experts. Due to the complex relationship between the variables of the cutting process, application of artificial intelligence approaches is wide feasible as modeling technique and functional for controller development. This work, presents a design of experiments, data analysis and model comparison for surface roughness prediction in face-milling of aluminum 6061-T6 considering tool spindle speed, feed rate, depth of cut and entry angle of the cutting insert as input variables. Measurements of average roughness are performed, then acquired data are preprocessed using the Principal Component Analysis (PCA) and Response Surface Methodologies (RSM). Once the proper variable arrangement is defined, a comparison between Feed Forward Back Propagation Neural Network (FFBPNN) and Radial Basis Function Neural Network (RBFNN) is performed based on the correlation coefficient between predicted and measured data. Results showed that Neural Network arrays have better prediction behavior than those based on RSM.
Advanced Adsorption Cooling cum Desalination Cycle: A Thermodynamic Framework
Authors: Chakraborty Anutosh , Thu Kyaw , Ng Kim Choon
Published: August 2012

We have developed a thermodynamic framework to calculate adsorption cooling cum desalination cycle performances as a function of pore widths and pore volumes of highly porous adsorbents, which are formulated from the rigor of thermodynamic property surfaces of adsorbent-adsorbate system and the adsorption interaction potential between them. Employing the proposed formulations, the coefficient of performance (COP) and overall performance ratio (OPR) of adsorption cycle are computed for various pore widths of solid adsorbents. These results are compared with experimental data for verifying the proposed thermodynamic formulations. It is found from the present analysis that the COP and OPR of adsorption cooling cum desalination cycle is influenced by (i) the physical characteristics of adsorbents, (ii) characteristics energy and (iii) the surface-structural heterogeneity factor of adsorbent-water system. The present study confirms that there exists a special type of adsorbents having optimal physical characteristics that allows us to obtain the best performance.
Simulation of Combustion in Porous Media With a Two-Energy Equation Model
Authors: deLemos Marcelo J. S. , Coutinho Jose´ E. A.
Published: August 2012

This work presents numerical results for two-dimensional combustion of an air/methane mixture in inert porous media using turbulence and radiation models. Distinct energy equations are considered for the porous burner and for the fuel in it. Inlet velocity and excess air-to-fuel ratio are varied in order to analyze their effects on temperature and flame front location. The macroscopic equations for mass, momentum and energy are obtained based on the volume average concept. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure-velocity coupling. Results indicate that for high excess air values, the gas temperature peaks are reduced. Also, for the same conditions the flame front moves towards the exit of the burner. Results also indicate that the same flame front behavior occurs as the inlet velocity increases.
A Simple Leakage Flow Model Including Viscous Effect
Authors: Qian Yuping , Cui Jian , Chen Chaoqing , Gong Yifang , Li Qiushi
Published: August 2012

The tip leakage flow rate can be directly linked to the loss and stall margin. In this paper, key factors affecting the tip leakage flow rate are explained based on a simple leakage flow model including viscous effect. Based on the numerical results, the flow model is verified in a low speed compressor rotor, and finally a simplified one-dimensional tip blockage model is established based on the Khalid’s model, which may be helpful in the design of compressor.
Dynamics of Wake Behind a Low Aspect Ratio Pitching Plate
Authors: De A. K.
Published: August 2012

Vectorized numerical simulations of unsteady wake behind a low-aspect ratio (double amplitude to span ratio 0.3) sinusoidally pitching plate (Strouhal number 0.4 and 0.5) are carried out for the Reynolds number, Re = 150,300. A non-staggered finite volume based predictor-corrector type of algorithm employing 2nd-order time integration and spatial schemes is used. The first sign of instability appears on the plate promoting separation which becomes more vigorous with the increase in Reynolds number. At low Reynolds number, the separation bubble originating near the plate diffuses in the near wake region and the whole wake oscillates with the plate. Fully developed vortex shedding from the rear edge of the plate is observed at a higher Reynolds number. The shed vortices are slowly convected and eventually diffuses completely at a large downstream distance. At a higher forced frequency the wake does not alter significantly at a lower Reynolds number. However, vigorous vortex shedding leading to two layers of vortex streets from both the sides of the plate is observed at a higher Reynolds number.
Electromechanical Characterization of Polyvinylidene Fluoride (PVDF) Films in Biaxial Extension
Authors: Mohan Sandhya , Lakshmana Rao C.
Published: August 2012

Polyvinylidene Flouride (PVDF) is a piezoelectric material which finds numerous applications as sensors and actuators. Significant developments have taken place in characterizing the mechanical and the electromechanical response of PVDF. The characterization of the response of PVDF reported in literature was conducted under uniaxial loading. This paper discusses the experimental investigations carried out to observe the response of PVDF films under uniaxial and biaxial loading conditions. These thin films have been subjected to static as well as dynamic mechanical loading. The response of the film under theses loading conditions was observed through the stress strain curves obtained for the different tests conducted. The anisotropic behavior of the material was also studied by conducting uniaxial static tests along two mutually perpendicular directions.
Improved Reverse Electro-Dialysis Using Membranes With Integrated Spacers
Authors: Burheim O. , Vermaas David A. , Nijmeijer Kitty , Pharoah J. G.
Published: August 2012

Reverse Electro-Dialysis, RED, utilises the energy of mixing between two solutions of different salinity by allowing ionic current to pass through the membranes and the two solutions such that cations are transport to the cathode and anions to the anode. [1–4.] The ionic current is converted to electronic current by red-ox reactions at the cathode and the anode. The membranes applied in this process are ionic selective, traditionally of uniform thickness and separated by a non-conductive spacer [5, 6]. Traditionally, non-conductive spacers have been deployed as eddy promoters and membrane spacers in salinity difference power extraction systems, such as Pressure Retarded Osmosis (PRO) and Reverse Electro-Dialysis (RED). For RED, traditional spacers inhibit parts of the ionic current paths in the fluid compartments and magnify the pressure drop imposed by the fluid flow between the membranes. [6] In a strive to lower the pressure drop in the fluid flow compartment and to increase the conductive region between the membranes, it is suggested to manufacture membranes with new shapes and profiles. [6] By modeling transport of mass and momentum in different geometries, spacing, mixing and active membrane area can be optimised with respect to increasing the power extraction. Such work has previously been done for traditional, i.e. non-electrochemical, flow in spacer separated membrane systems. A classical, approach has been to study submerged and non-submerged non-conductive spacer rods in fluid flow between two parallel plates (membranes) for Reynolds numbers (Re) from 50 and upwards. [7–17] This work discusses how spacers united with the reactant surface (membrane) will affect the mixing and the pressure drops of RED systems with Re numbers between 1 and 100, the expected operational Re number range for RED [6, 18, 19]. This is essential for the power production of RED. For a process converting renewable energy present in nature, such as RED, optimising these parameters is detrimental for the exergy yield. In going from a laboratory scale with a 10 × 10 cm2 cross sectional membrane to a large scale of 100 × 100 cm2, the Reynolds number (Re) increases from 10 to 100 simply because the volume flow is proportional to the flow length. Since it is within this range that eddies starts to get promoted by spacers, different mixing properties is expected exist when comparing laboratory and industrial scaled RED systems.
Effects of UV-Visible Irradiation on Pool Boiling Behavior of Copper
Authors: Hunter Chad N. , Glavin Nicholas R. , Voevodin Andrey A. , Turner David B. , Check Michael H. , Putnam Shawn A. , Fisher Timothy S.
Published: August 2012

Roughened copper substrates were exposed to a broadband UV-VIS light source during nucleate boiling at a heat flux of 60–70% of the amount expected to result in critical heat flux (CHF) without exposure to a light source. The surface temperature decreased by 0.5–1.0°C within minutes after the UV-VIS light exposure began. CHF occurred after less than 20 minutes of exposure to the light source. Nanoscale features were observed in the light-exposed region of the copper surface after boiling, which were primarily associated with formation of Cu2O. The induced CHF likely occurred due to surface oxide formation, a resultant decrease in wettability of the surface.
Resonant Frequency and Sensitivity of an AFM Microcantilever Modeled by the Non-Local Theory
Authors: Khosravani E. , Kahrobaiyan M. H. , Ahmadian M. T.
Published: August 2012

In this paper, utilizing the non-local theory, the resonant frequency and sensitivity of an AFM microcantilever are investigated. To that end, the governing equation of motion and corresponding boundary conditions are obtained using the variational approach. Afterwards, the resonant frequency and sensitivity of the AFM microcantilever are derived analytically and depicted in some figures versus the contact stiffness of the sampling surface. The results of the current model are compared to those of the classical theory. The comparison shows that the difference between the results of the non-local theory and those of the classical theory is significant when the non-local parameter is high but it diminishes as the non-local parameter decreases.
Reduction Effects of Suspended Particulate Matters in Air by Thermal Moisture Swing Method
Authors: Onoda Nagisa , Ishiguchi Shota , Nakabeppu Osamu
Published: August 2012

We are studying the effects of thermal moisture swing air-cleaning method on removal of suspended particulate matter, SPM. This method continuously humidifies sample air with heating and dehumidifies it by cooling, in a channel. It was experimentally demonstrated that the thermal moisture swing method reduces SPM suspended in sample air. The experimental result showed reduction of SPM above 10 nm in particle size, and the removal ratio increased with intensifying the thermal moisture swing. The SPM removal mechanism of this method was theoretically estimated. The estimation suggests that the reasons for the SPM reduction are suction flow accompanying condensation and thermophoresis. These phenomena would transport SPM to cooling wall of the dehumidifier. Also, diffusional deposition and gravitational sedimentation would transport SPM to the wall of the channel. And, the transported particles are separated from the air with adhering on the wall. We estimated the effects of these phenomena on SPM removal using simple model and energy consumption. The estimation qualitatively agreed with the experimental result.
Design and Analysis of a Biomimetic Wire-Driven Robot Arm
Authors: Li Zheng , Du Ruxu , Lei Man Cheong , Yuan Song Mei
Published: August 2012

Inspired by the octopus and snakes, we designed and built a wire-driven serpentine robot arm. The robot arm is made of a number of rigid nodes connected by two sets of wires. The rigid nodes act as the backbone while the wires work as the muscle, which enables the 2 DOF bending. The forward kinematics is derived using D-H method, while the inverse kinematics and its workspace can be solved by geometric analysis. To validate the design, a prototype is built. It is found that the positioning error of the robot arm is generally less than 2%. The advantage of this robot arm is that with several nodes fixed the rest nodes are still controllable. The positioning error is smaller when the fixed node is closer to the end effector.
Model-Based Estimation of Mechanical Characters of Arterial Vessels Using Experimental Dynamic Response Data
Authors: Vali Rahil , Saito Takashi
Published: August 2012

As both the geometric and stiffness changes may occur in atherosclerosis, it is necessary to estimate respective contribution from structural and material characteristics in the stiffness index. In this study, we employ the primary mechanical model based on one of elastic shell theory, Love’s theory and look upon a blood vessel as a ring model. Furthermore in order to confirm validity of the model, the experiments were carried out on artificial tubes. The circulating circuit is applied as the circulatory system of human body including tubes, and water is designated as the working fluid of the circulating circuit. Experimental data are applied for mechanical model and mechanical parameters are identified using Downhill simplex method as the inverse problem. In this study stiffness index and damping ratio were identified and the result of Love’ theory was compared with measurement data and Donnell’s theory. The result shows that present study can confirm the measurement data with the fine approximation.
Conduit Flow Control Through Magnetorheology
Authors: Letelier Mario F. , Stockle Juan S. , Siginer Dennis A.
Published: August 2012

In this paper it is addressed the problem of flow stability in conduits when an essentially steady flow is perturbed by undesirable fluctuations of the pressure gradient. This problem may arise when working conditions in conduit systems induce sporadic or permanent oscillations of the pressure at the end of some conduits. In cases where the flow occurs in closed circuits and it is important to reduce or eliminate flow fluctuations, it is possible to impose flow control by making use of the magnetorheological properties of some fluids. An analytical model is presented in which the working fluid is assumed to be affected by a magnetic field whose strength is proportional to the instantaneous rate of flow. In this way, it is shown that oscillatory perturbations of an otherwise constant pressure gradient can be damped away through the synchronized oscillations of the yield stress generated in the fluid by the magnetic field. The paper includes the solution of the analytical model and several examples of applications.
Designing in Safety Through Early Safety Requirements Management
Authors: Lyver John W. , Prassinos Peter G. , Bui Chinh T.
Published: August 2012

The National Aeronautics and Space Administration (NASA) has developed a set of Agency-level requirements which cover the risk areas associated with the safety, reliability, maintainability and quality assurance disciplines. This set of requirements applies to NASA activities ranging from space exploration to aeronautics research to product quality to the protection of the NASA family. With the establishment of NASA’s new human exploration programs, NASA realized that it needed to develop a methodology for sorting through the wide variety of knowledge captured in the Agency requirements and identify how those requirements are applicable to each emerging program. This paper will highlight the process used by NASA to filter the thousands of requirements into a concise set which would reduce overall programmatic risk without overburdening the program.
A Size-Dependent Beam Element Based on the Modified Couple Stress Theory
Authors: Kahrobaiyan M. H. , Khajehpour M. , Ahmadian M. T.
Published: August 2012

In this paper, the modified couple stress theory is employed to develop a size-dependent beam element able to predict the size-dependency observed in microbeams. The stiffness matrix is obtained for the aforementioned beam element. As an example, the deflection of a microcantilever is evaluated using the proposed beam elements and the results of the finite element method are compared to the analytical results obtained by the classical beam theory. The maximum deflection of the beam is depicted versus the ratio of the beam thickness to the material length scale parameter, the parameter appearing in non-classical continuum theories. The results show that when the characteristic size of the beam (thickness, diameter, etc) is small, like the beam used in MEMS and NEMS, the difference between the results of the current model and those obtained by the classical beam theory is significant but it diminishes as the characteristic size increases.