bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Hybrid Method for Mid-Frequency Vibration of Beam-Plate System Under External Point Loading
Authors: Zhu Danhui , Chen Hualing , Kong Xiangjie , Zhang Wenbo
Published: April 2014

In this paper, a new hybrid method combining finite element analysis (FEA) and energy finite element analysis (EFEA) is developed for predicting the vibrational response of beam-plate system in mid-frequency range, which enables the local detailed response of the system to be obtained. The waves produced in the system exhibit low- and high-frequency vibrational characteristics simultaneously, which are called stiff member and flexible member separately. The former is modeled using classical FEA, meanwhile the latter is simulated by EFEA. However, unlike classical EFEA, the vibrational energy is considered as the superposition of the direct field and the reverberant field associating the mechanism of wave propagation in high-frequency. Furthermore, the power transfer between two fields is considered according to the transferring pathway analysis of power flow, which is more accurate than the traditional EFEA at the driving points and boundaries. Additionally, the compatibility of the stiff and flexible members is formulated in a global matrix of the system, in which the interactions between these two members are captured. The new developments are validated by a beam-plate system with a line junction under an external point loading applied on the beam, and good correlations are found when compared with the results from very dense classical FEA model.
Systems in Prosthetic Hands and the Relationship With Their Performance
Authors: Díaz-Montes Julio C. , Dorador-González Jesús Manuel
Published: April 2014

A review of the state of the art in prosthetic hands is presented; this review covers the most common commercial prosthesis and prototypes under development.

In this analysis, prosthetic devices were divided in six systems: actuation, reduction, blocking, transmission, flexion and support. The information obtained is presented according to those systems.

The most important features of each system are presented together with their relationship with the performance of the entire prosthesis. An analysis that indicates the way in which prosthesis take advantage of the capabilities of current technologies is presented. Recommendations for improving the performance of upper limb prosthesis are proposed.
Simulation of an Industrial Tangentially Fired Boiler Firing Metallurgical Gases
Authors: Tang Guangwu , Wu Bin , Johnson Kurt , Kirk Albert , Zhou Chenn Q.
Published: April 2014

In industrial environments, boiler units are widely used to supply heat and electrical power. At an integrated steel mill, industrial boilers combust a variable mixture of metallurgical gases combined with additional fuels to generate high-pressure superheated steam. Most tangentially fired boilers have experienced water wall tube failures in the combustion zone, which are thought to be caused by some deficiency in the combustion process. The challenge faced in this present process is that there are very limited means to observe the boiler operation. In this study, a three-dimensional Computational Fluid Dynamics (CFD) modeling and simulation of an industrial tangentially fired boiler firing metallurgical gases was conducted. Simulation results obtained from the assembled CFD model were validated by industrial experiments. A quick comparison of the flame shape from the simulation to the actual flame in the boiler showed a good agreement. The flow field and temperature distribution inside the tangentially fired boiler were analyzed under the operation conditions, and a wall water tube overheating problem was observed and directly related to the flow characteristics.
Automatic Refinement of FE Shell Models Based on a Local Energy Function
Authors: Carminelli Antonio , Catania Giuseppe
Published: April 2014

This paper deals with an adaptive refinement technique of a B-spline degenerate shell finite element model, for the free vibration analysis of curved thin and moderately thick-walled structures. The automatic refinement of the solution is based on an error functional related to the density of the total potential energy. The model refinement is generated by locally increasing, in a sub-domain R of a local patch domain, the number of shape functions while maintaining constant the functions polynomial order. The local refinement strategy is described in a companion paper, written by the same authors of this paper and presented in this Conference. A two-step iterative procedure is proposed. In the first step, one or more sub domains to be refined are identified by means of a point-wise error functional based on the system total potential energy local density. In the second step, the number of shape functions to be added is iteratively increased until the difference of the total potential energy, calculated on the sub domain between two iteration, is below a user defined tolerance. A numerical example is presented in order to test the proposed approach. Strengths and limits of the approach are critically discussed.
Control Mechanisms in Oscillatory Motor Behavior
Authors: Piovesan Davide , Huang Felix C.
Published: April 2014

Studies on unimpaired humans have demonstrated that the central nervous system employs internal representations of limb dynamics and intended movement trajectories for planning muscle activation during pointing and reaching tasks. However, when performing rhythmic movements, it has been hypothesized that a control scheme employing an autonomous oscillator — a simple feedback circuit lacking exogenous input — can maintain stable control. Here we investigate whether such simple control architectures that can realize rhythmic movement that we observe in experimental data. We asked subjects to perform rhythmic movements of the forearm while a robotic interface simulated inertial loading. Our protocol included unexpected increases in loading (catch trials) as a probe to reveal any systematic changes in frequency and amplitude. Our primary findings were that increased inertial loading resulted in reduced frequency of oscillations, and in some cases multiple frequencies. These results exhibit some agreement with an autonomous oscillator model, though other features are more consistent with feedforward planning of force. This investigation provides a theoretical and experimental framework to reveal basic computational elements for how the human motor system achieves skilled rhythmic movement.
Influences of Water Injection Rate and Oil Length on Oil Slug Mobilization in a Capillary Model
Authors: Dai Liming , Zhang Yihe
Published: April 2014

In this paper, numerical research has been investigated for oil-water two-phase flow in a capillary model by software FLUENT. The flow behavior of the oil slug and the influences of both water injection rate and oil slug length have been considered. Results indicate that numerical model performs well in simulating oil slug shape variation; meanwhile, the maximum driven pressure magnitude is proportional to the water injection rate and the oil slug length, and the flow time is inversely proportional to the water injection rate.
Energy Control of Nonlinear Non-Homogeneous Chains
Authors: Udwadia Firdaus E. , Mylapilli Harshavardhan
Published: April 2014

In this paper, we consider the problem of energy control of an n-degrees-of-freedom system consisting of a chain of masses wherein each of the masses is connected to its neighboring mass with the help of a nonlinear memoryless spring element. The qualitative nature of the nonlinearity in each of the spring elements can, in general, be different. Both fixed-fixed and fixed-free boundary conditions are considered. The energy control problem is approached from a new perspective — that of constrained motion. For a given set of masses at which the control is to be applied, explicit closed form expressions for the nonlinear control forces are derived by using the fundamental equation of mechanics. Through the use of the invariance principle, we show that these control forces provide global asymptotic convergence to any ‘given’ non-zero energy state provided that the first mass, or the last mass, or alternately, any two consecutive masses in the chain are included in the subset of masses that are controlled. The results obtained in this paper are, in general, applicable to any finite degrees-of-freedom, fixed-fixed or fixed-free nonlinear chain whose spring potentials are described by a class of twice continuously differentiable, strictly convex functions, which possess a global minimum at zero displacement, with zero curvature possibly only at zero displacement.
Comparing Engineering Education Systems Among USA, EU, Philippines and South Africa
Authors: Alves Anabela C. , Kahlen Franz-Josef , Flumerfelt Shannon , Siriban Manalang Anna Bella
Published: April 2014

Globalization has permeated our personal and professional lives and careers over the past two decades, to a point where communication, product development, and service delivery now are globally distributed. This means that the globalization of engineering practice is in effect. Large corporations tap into the global market for recruitment of engineers. However, the education of engineers occurs within the context of individual Higher Education Institutions. Engineers are educated with varying pacing and scoping of higher education programming with varying methods and pedagogy of higher education teaching. The expectations for engineering practice normed from the corporate side within the engineering marketplace, therefore, often do not match the widely dispersed educational experiences and outcomes of engineering education delivery. This gap brings challenges for all stakeholders, employers, higher education and the engineering graduate. But particularly, university education systems which traditionally are slow to respond to shifting market trends and demands, are expected to realign and restructure to answer this shortfall.

A response to this shortfall has been prepared independently in different regions and countries. This paper discusses the response from Europe, USA, South Africa and Philippines. The European Commission started building a European Higher Education Area (EHEA) with the intention of promoting the mobility and the free movement of students and teachers in European tertiary education. US universities are introducing a design spine and strengthening students’ systems thinking and problem solving competencies. Philippines is trying to be aligned with ABET system from US. South Africa universities are evolving to a solid core undergraduate engineering curriculum with a limited set of electives available to students which include project-based learning. This is intended to address the education-workplace gap as well.

This theoretical paper will provide a comparison study of the differences between the Engineering Education in USA, EU, Philippines and South Africa. The authors will compare current trends and initiatives, aimed at improving the readiness and competitiveness of regional engineering graduates in the workplace. Given that several worthwhile initiatives are underway, it is possible that these initiatives will remain as disparate responses to the need for the globalization of engineering education. Lean performance management systems are widely used in engineering practice internationally and represent one possible rallying concept for the globalization of engineering education in order to address the education-workplace gap. Therefore, this paper examines whether the introduction of a Lean Engineering Education philosophy is a worthwhile global curricular innovation for engineering courses.
Analytical Temperature Distribution in a Multi-Layer Tissue Structure in the Presence of a Tumor
Authors: Sarkar Daipayan , Jain Ankur , Haji-Sheikh A.
Published: April 2014

Analytical study of bioheat transfer is of significant importance for a number of biomedical applications including cryopreservation of tissue and thermal therapy for cancer. A sound fundamental understanding of thermal behavior of tissue in response to an externally applied stimulus helps design effective therapies and protocols. This paper derives an analytical solution in a multi-layer two-dimensional structure with arbitrary, space-dependent heat generation occurring in each layer. This geometry effectively models multiple layers of skin, with heat generation due to cancerous cells in the basal layer. The Pennes bioheat transfer equation is solved for the multi-layer analytically, wherein the temperature in each layer is explicitly a function of space and the thermo-physical properties of the layer. The resulting analytical temperature profile agrees well with finite-element simulations and is also in good agreement with a previously published experimental study. Results derived in this work illustrate the effect of the presence of cancerous cells on the thermal profile of the skin. Further, the model helps to understand the effect of external cooling and heating stimuli.
Integrated Design and Production Problem Solving in Industry-Sponsored Academic Education
Authors: Bzymek Zbigniew M. , Nunez Manuel A.
Published: April 2014

In this paper the authors’ experience of teaching an industry sponsored course in Senior Design. The course has been jointly taught by two instructors, one from the Mechanical Engineering Department of the School of Engineering, and the other from the Operations and Information Management Department of the School of Business; and it is part of the Management and Engineering for Manufacturing program at UConn [1]. The student projects have been sponsored by local companies in industries ranging from aerospace to food production. The projects have one main goal: to find the best possible engineering design solution while achieving high production process efficiency. Such an approach relies on the talent of the designer, i.e., the student’s or engineer’s ability to develop a “perfect product” on one side, and the efficiency of the production solutions on the other. In practice, it is difficult to achieve such combined design process formalization successfully. For this reason, the problem solving relies on students’ skills, their knowledge and experience, and the instruction in the course. In particular, the Arena and DELMIA/Quest simulation packages were used for both design and production problem solving. In searching for an ideal solution cost effectiveness and economic constraints were also considered.

The experience gained from over ten years teaching of this course is described and analyzed in the paper. Some results of the course are presented and recommendations for further teaching and practice of industry-sponsored courses integrating engineering and production problem solving are discussed.
Benchmarking the Accuracy of Inertial Measurement Units for Estimating Joint Reactions
Authors: McGinnis Ryan S. , Hough Jessandra , Perkins N. C.
Published: April 2014

Newly developed miniature wireless inertial measurement units (IMUs) hold great promise for measuring and analyzing multibody system dynamics. This relatively inexpensive technology enables non-invasive motion tracking in broad applications, including human motion analysis. The second part of this two-part paper advances the use of an array of IMUs to estimate the joint reactions (forces and moments) in multibody systems via inverse dynamic modeling. In particular, this paper reports a benchmark experiment on a double-pendulum that reveals the accuracy of IMU-informed estimates of joint reactions. The estimated reactions are compared to those measured by high precision miniature (6 dof) load cells. Results from ten trials demonstrate that IMU-informed estimates of the three dimensional reaction forces remain within 5.0% RMS of the load cell measurements and with correlation coefficients greater than 0.95 on average. Similarly, the IMU-informed estimates of the three dimensional reaction moments remain within 5.9% RMS of the load cell measurements and with correlation coefficients greater than 0.88 on average. The sensitivity of these estimates to mass center location is discussed. Looking ahead, this benchmarking study supports the promising and broad use of this technology for estimating joint reactions in human motion applications.
Simple Mechanistically Consistent Formulation for Volume-of-Fluid Based Computations of Condensing Flows
Authors: Rattner Alexander S. , Garimella Srinivas
Published: April 2014

Numerous investigations have been conducted to extend adiabatic liquid-gas VOF flow solvers to include condensation phenomena by adding an energy equation and phase-change source terms. Some proposed phase-change models employ empirical rate parameters, or adapt heat transfer correlations, and thus must be tuned for specific applications. Generally applicable models have also been developed that rigorously resolve the phase-change process, but require interface reconstruction, significantly increasing computational cost and software complexity. In the present work, a simplified first-principles-based condensation model is developed, which forces interface-containing mesh cells to the equilibrium state. The operation on cells instead of complex interface surfaces enables the use of fast graph algorithms without reconstruction. The model is validated for horizontal film condensation, and converges to exact solutions with increasing mesh resolution. Agreement with established results is demonstrated for smooth and wavy falling-film condensation.
Development of K-12 Teaching Modules by Undergraduate Researchers Amidst Their Own Professional Growth as Research Participants
Authors: Kumpaty Subha
Published: April 2014

The author has been successful with Research Experiences for Undergraduates (REU) Site for the past 15 years attracting funding from the National Science Foundation for the intense 10-week summer research program for undergraduate students in the field of additive manufacturing and its variety of applications in many disciplines. In the current site, a novel undertaking was initiated by asking REU participants, who are junior and senior year undergraduate standing at the time of participation, to come up with ways they can communicate their research to K-12 students and provide teachers a tool for teaching some concepts in the area of their research. Seven modules have been developed by the seven participants and the modules have been found to be very attractive to the teachers in K-12. The paper presents the inner workings of the undergraduate participants getting out of their comfort zones from research to pedagogy about their own work, especially when we need such role models for our children in K-12. It is also exciting to see teachers willing to take REU participants’ finished modules for potential use in their classrooms.
The Research on Performance of Hovercraft Gas Turbine Anti-Icing Device
Authors: Wang Zhongyi , Li Fei , Zhao Zhengheng , Yuan Changlong
Published: April 2014

An anti-icing device is designed for resisting the ice accretion occurring in the air intake system of hovercraft gas turbine, which may affect its normal operation. The anti-icing purpose was achieved by mixing hot bleed air from the engine compressor and cold intake ambient air. Some research on the bleed air heating system was done by using 3D numerical simulation method. Under the set parameter of bleed air, the ambient temperature range for different bleed air flow was obtained and the corresponding anti-icing effect was also simulated. When the ambient temperature changed, the influence of anti-icing device’s working on total pressure loss of air intake system and the distributing condition of the compressor inlet surface velocity nonuniformity were investigated, and their changing law under different icing condition was obtained. The researching results provide theoretical and practical guidance and support for ships equipped with gas turbine when sailing in low temperature region.
Quantifying the Effect of Plug-In Electric Vehicles on Future Grid Operations and Ancillary Service Procurement Requirements
Authors: Harris Chioke B. , Webber Michael E.
Published: April 2014

As plug-in electric vehicles (PEVs) grow in popularity, there is increasing research interest in the interaction between PEVs and the electric grid. Much of the previous work in the literature relies on an assumption that PEV charging will be scheduled, and that the duration and magnitude of charging loads can be modulated to suit the needs of the utility and the system operator. While access to the data or owner input necessary for charge scheduling and management might be technically feasible today, it is unclear whether vehicle owners will be amenable to providing these data or accepting utility control of their charging choices.

Because of these uncertainties in the future relationship between electric utilities and PEV owners, this study seeks to examine the market effects of vehicles in the absence of the additional data utilities would need to realize these alternate, “optimal” PEV charging scenarios. In particular, this study focuses on quantifying the potential uncertainty in vehicle charging loads on an energy and power basis.

Monte Carlo methods were applied to vehicle trip data from the National Household Travel Survey (NHTS) to generate simulated driving profiles for individual vehicles. Using these profiles, six PEV fleet sizes were studied, ranging from 1,000 to 500,000 vehicles, to determine whether fleet size had a linear effect on the stochasticity of vehicle charging loads. Following the Monte Carlo simulations, these loads were examined independent of and compared to net load (load minus wind generation).

Results from the Monte Carlo simulations indicate that even for the largest PEV fleet sizes studied, variability in average charging loads is on the order of 10 MW, less than 0.2% of the magnitude of charging load for those fleet sizes. In comparison with electricity demand in the Electric Reliability Council of Texas’ (ERCOT) operating area, these charging loads represent a 1% increase above typical summer peak loads. Unfortunately, while the relative increase in demand is small, the timing of peak charging load is nearly coincident with summer peak demand.

The simulation approach was validated by comparing the results against empirical vehicle charging data collected by the Pecan Street Research Consortium from households in Austin, Texas. Simulated and empirical vehicle charging trends showed generally good agreement, with similar charging times but slightly different charging durations. The alignment between the two charging profiles indicates that the simulation methodology applied here with NHTS travel data can be used to predict electric load for vehicle charging when empirical historical charging data are not available.
Optimal Design of Electrode Structure and Microfluidics Channel for Effective Particle Separations
Authors: Chen Yun , Manoochehri Souran
Published: April 2014

This paper presents the optimal design of electrode structure and microfluidics channel for effective particle separations. The purpose of the microfluidics chip is to generate the DEP (dielectrophoresis) force within the micro channel to separate both negative DEP (nDEP) and positive DEP (pDEP) particles of same sizes. The particles will experience DEP force when passing through the electric field created by electrode arrays located in different positions within the channel. The channel contains several electrode arrays where the pDEP particles are moved away from the electrodes and the nDEP particles are attracted towards them. In some existing microfluidics chips, because of the high intensity of the electric field around the electrodes, which results in a very high DEP force near the electrodes, most of the positive DEP particles are captured in the space between electrodes without being guided to the target outlet. Moreover, the effective area of DEP force is limited to a small region near the corner of the electrodes, therefore only those particles very close to the electrodes will experience sufficient attractive forces to be guided towards the target locations. This will decrease the efficiency of the particle separation. In this study, we developed an optimization methodology for design of electrode configurations using numerical modeling. The optimized electrode structure can provide much more evenly distributed DEP field. The design of the channel, the number and position of the electrode arrays were optimized in order to improve the efficiency of the particle separation. Finally, the optimized electrode structure and microfluidics channel were modeled and tested using multiphysics simulation software and the results show that this optimized design of microfluidics channel can provide high throughput and more effectiveness for particle separation compared to many existing microfluidics devices.
Effect of Charge Distribution at the Three Phase Contact Line for an Electrolyte Drop
Authors: Sarkar Dibyo , Das Siddhartha , Mitra Sushanta K.
Published: April 2014

In this paper, we obtain the velocity field in a wedge in a Three Phase Contact Line (TPCL) in an electrolyte drop which is evaporating on a charged solid. Combination of an electrolyte solution and the charged surface leads to the formation of an Electric Double Layer (EDL), which in presence of the evaporation-triggered pressure-driven transport, leads to the generation of a streaming current that causes an electrokinetic transport. Hence, we analyze for the first time an electrokinetic transport in a charged wedge in presence of an evaporation-induced advective flux. Our results exhibit flow patterns that are distinctly different as compared to that of the case where there is no such electrokinetic transport and the problem is merely that of evaporation in a wedge.
Treatment of Arrhythmias by Radiofrequency Ablation
Authors: Ulucakli M. Erol , Sheehan Evan P.
Published: April 2014

Radiofrequency ablation may be described as a thermal strategy to destroy tissue by increasing its temperature and causing irreversible cellular injury. Radiofrequency ablation is a relatively new modality which has found use in a wide range of medical applications and gained acceptance. RF ablation has been used to destroy tumors in the liver, prostate, breasts, lungs, kidneys, bones, and eyes. One of the early clinical applications was its use in treating supraventricular arrhythmias by selectively destroying cardiac tissue. Radiofrequency ablation has become established as the primary modality of transcatheter therapy for the treatment of symptomatic arrhythmias. Radiofrequency catheter ablation of cardiac arrhythmias was investigated using a finite-element based solution of the bioheat transfer equation. Spatial and temporal temperature profiles in the cardiac tissue were visualized.
Use of Catalog Mining to Extract Valuable New Knowledge Hidden in Trivial Parameters
Authors: Kodama Hiroyuki , Hirogaki Toshiki , Aoyama Eiichi , Ogawa Keiji
Published: April 2014

We have developed a process that uses both hierarchical and non-hierarchical clustering methods to mine data in tool catalogs. Principal component regression is used for quantifying the correlation between the predictor and criterion variables, and multiple regression analysis is used for creating an end-milling condition determinant matrix for each cluster. We fixed the outside diameter of the tool shape parameter as a constant trivial value and examined the correlation between the other tool shape parameters and the end-milling conditions. We thereby extracted valuable new knowledge hidden in trivial parameters and built a hypothesis in regards to data-mining effect. We found that cutting speed is the most important of the criterion variables and that the number of determination coefficient is no less important for determining prediction accuracy of end-milling condition decision equations. End-milling condition decision determinants derived from our data-mining process are important indicators for adjusting end-milling conditions on the basis of end-milling efficiency and tool life.
Flutter Suppression of Wind Turbine Blade Using Adaptive Control
Authors: Li Nailu , Balas Mark J.
Published: April 2014

The variation of aeroelastic system dynamics is treated as the change of time-varying aerodynamic loads over rotating wind turbine blade. An Adaptive Control scheme is introduced to suppress blade fluttering, caused by unsteady aerodynamic loads, with trailing-edge flap. The robustness and effectiveness of designed Adaptive Controller are shown by good simulation results. For stability analysis, the proposed Adaptive Stability Theorem is proved theoretically by Kalman-Yacubovic Lemma and also illustrated numerically by certain case.
Influence of Skewing of Contact Face on Performance of Wave Rotor Refrigerators and Superchargers
Authors: Dai Yuqiang , Liu Fengxia , Wu Jintao , Wei Wei , Hu Dapeng , Liu Xuewu
Published: April 2014

As a novel generation of rotational gas wave machines, wave rotor machines such as wave rotor refrigerators (WRR) and wave rotor superchargers (WRS) are unsteady flow devices. In their passages two gas streams (with different pressure or even different phases) comes into direct contact can exchange energy due to the movement of shock waves and expansion waves. A detailed study shows that, when rotor channels open to the high pressure port gradually, the contact face in rotor channels inevitably skews, which is always accompanied with reflection of shockwaves. This causes very large energy dissipation and influences adversely on the refrigeration performance of WRR or the supercharging performance of WRS. In this work, factors such as centrifugal forces, Coriolis forces, gradual channel opening and gradual channel closing, etc, which influence the wave transportation and skewing of shock waves and contact faces are studied by means of computational fluid dynamics and experiments.

The skewing of contact faces causes uneven distribution of velocity and large local loss. With rotation Mach number smaller than 0.3, the skewing of contact face can be alleviated. To reduce the adverse influence of rotation Mach number, a smaller rotor channel width or higher rotational speed is necessary.

The rotation effect plays an important role for the skewing of gas discontinuities. Both the centrifugal and Coriolis forces of wave rotor cannot be ignored with the Rossby number of 1.3∼3.5. To reduce the skewing loss of contact face, a lower rotational speed seems necessary. The rotation speed of wave rotors has dialectical influences on the skewing of shock waves and contact faces.

The jetting width of high pressure port is the key factor of the gradual opening of rotor channels. A feasible way to reduce skewing losses of gas waves is to optimize the ratio between high pressure port width and channel width. The validation experiments have got at least 3∼5% rise of isentropic efficiency for WRRs.
Analytical and Experimental Investigation to Determine the Variation of H-W-B Constants for a Scaled Forced Circulation Flat Plate Solar Water Heater
Authors: Chandavar Arunachala , Bhatt Siddhartha , Krishnamurthy Sreepathi
Published: April 2014

Fixed tilt flat plate solar thermal collectors, popularly known as solar water heaters still remain as one of the most interesting technologies for utilization of solar energy. The system performance deteriorates due to scaling because of continuous use of hard water as feed water. The present study deals with the experimental and analytical approach to determine the variation of H-W-B (Hottel–Whillier–Bliss) constants (which compactly represent the efficiency characteristics of a solar water heater) due to variation in solar power input and degree of scaling in case of forced circulation system without considering the variation of input power to the circulating pump. Indoor tests are performed with a copper tube to investigate the flow characteristics. This forms a part of conventional forced circulation system, in place of the usual nine-fin tube array in a full fledged collector. In indoor tests, electrical heating is favored to simulate solar radiation level. Various energy parameters are determined and compared by incorporating the developed numerical code FLATSCALE. Variation between experimental and analytical mass flow rate, overall heat loss coefficient, H-W-B constants with simulated solar radiation level are plotted. In scaled condition, the drop in instantaneous efficiency is due to both scale thickness and reduced water flow rate. Scale thickness acts as an additional thermal conductive resistance between absorber plate and flowing water. Overall heat loss coefficient increases as absorber plate temperature is high during reduced flow rate. The maximum deviation observed is 21.68 % in mass flow rate, 14.64 % in absorber plate mean temperature, 7.86 % in overall heat loss coefficient and 12.04 % in instantaneous efficiency. Compared to a clean tube, a highly scaled tube of 3.7 mm scale thickness indicates a drop of 4.76 % in instantaneous efficiency and 40.28 % in mass flow rate. It is concluded that the growth of scale in forced circulation system does not affect the instantaneous efficiency significantly because of the margin in heat carrying capacity of water inspite of high drop in the flow rate.
Constructal Design for Efficiency: The Case of an Entropic Wall With Circulating Water
Authors: Dumas Antonio , Trancossi Michele , Madonia Mauro
Published: April 2014

This paper presents an effective analysis on the relation between the changing architecture of a flow system and the maximization of global performance under constraints. An entropic wall with circulating water based on LESP concept has been analyzed. It is a wall with good acclimatizing properties generated by circulating water, which is thermally stabilized by exchanges in the ground. The system has been considered by different levels of complexity. The thermal structure is optimized by considering the system as a sequence of building blocks with assemblies of stepwise larger sizes: an entire wall and the entire building.

The optimal flow network is tree shaped. Different levels of optimization have been performed according to the different scale levels. On an elemental scale is has been optimized the properties of the single elemental block constitutive of the considered wall. On a single wall level, the system has been optimized to optimize internal fluid distribution system, maximizing the thermal uniformity and minimizing the weight of the wall.

The calculation process have been improved enriching the Constructal approach by a novel calculation method which has been defined for introducing more systemic algorithmic calculations at engineering level. This method has been defined as Constructal Design for Efficiency.
Cycling Aerodynamics: The Effect of Rider Position on Aerodynamic Drag
Authors: Fulton Alexander B. , Lipp Genevieve M. , Reid Jeffrey D. , Mann Brian P.
Published: April 2014

Competitive cyclists seek to maximize their efficiency by minimizing the influence of resistive forces. At the high speeds maintained during competition, aerodynamic drag is the primary resistive force. This paper investigates the influence of a cyclist’s body position using models of aerodynamic drag and elucidates the time benefit of various body positions. Mathematical models from prior work, which use cyclist mass and body position angles, have been used to determine the projected frontal area of a cyclist and the aerodynamic drag. Graphical representation of the non-linear relationship between aerodynamic drag and an increasing velocity are also provided. Finally, simulations are produced for a 40 km time trial course, and the results indicate a maximum performance increase of 20.71% due entirely to rider body position when exerting 400 W. We conclude aerodynamic efficiency is crucial in competitive cycling, and its significant correlation with rider body position should not be ignored.
Effect of Extrusion Parameters on Mechanical Properties of Al6061-Ni-P Coated SiC Composites
Authors: Suryanarayana Ramesh Chinnakurli , Ramakrishna Sikhakolli , Attaullah Ummar Khan , Badnur Smitha Hanumantha , Saheb Kumar
Published: April 2014

Extrusion of metal matrix composites (MMCs) is a very challenging one where in the bond between the reinforcement and the matrix alloy is crucial in getting high quality extrusions for industrial applications. In recent years researchers are focusing on developing aluminium based composites with metallic coated reinforcement to achieve good interfacial bonds to ensure smooth load transfer from the matrix on to reinforcement. However no information is available as regards hot extrusion of metallic coated reinforced MMCs. In the light of the above, the present work focuses on a systematic investigation on effect of extrusion process parameters on mechanical properties of Al6061-Ni-P coated SiC composites.

From the investigation, it is observed that hardness, yield and ultimate strength of Al2014-SiC (Both uncoated and Ni-P coated) composites are higher when compared with the matrix alloy for all the extrusion ratios studied (4:1,5:1,10:1,15.5:1) at a given extrusion temperature. However, the ductility of composites decreases with increase in extrusion ratios. Further, heat treatment has a significant effect on the studied mechanical properties. Increase in extrusion temperatures at a given extrusion ratio has resulted in decrease in hardness and strength properties of both matrix alloy and developed composites.
Numerical Modelling and Experimental Validation of Intervertebral Discs
Authors: Azarnoosh Marzieh , Stoffel Marcus , Weichert Dieter
Published: April 2014

Over the last several decades investigations of replacement material for intervertebral disc (IVD) have been an important topic in medical research. The challenge is to create materials whose mechanical behavior ideally matches that of the articular cartilage comprising the native discs. Thus, the study of articular cartilages underlying mechanical characteristics is a key issue for the successful development and refinement of replacement materials.

Using both experimental and cartilage histostructural data, including fiber orientation, a visco-hyperelastic-diffusion (VHD) material model is developed and implemented. This allows us to numerically study the mechanical behavior of an IVD consisting of a cartilaginous ring surrounding a fluid core.

In this work, a three dimensional finite element (FE) model is developed to simulate the behavior of an IVD under various loading conditions. Finally, model parameters are iteratively determined by comparing the simulation results to compression tests on corresponding discs performed in a MTS machine with a tempered nutrient solution.
Rotation Effects on Hub Drag
Authors: Forbes Alexander , Raghav Vrishank , Mayo Michael , Komerath Narayanan
Published: April 2014

The effects of rotation in a freestream on the drag, side force and torque of a generic helicopter rotor hub are studied using azimuth-resolved load measurements in a low speed wind tunnel. The hub is directly mounted to a stepper motor placed on a load cell, enabling extraction of all 6 load components with sufficiently high azimuthal resolution. The results confirm findings in the prior literature that rotation does not significantly increase hub drag in a freestream. However, the addition of a scissors linkage to the hub resulted in a 10 percent increase in drag above the prior generic configuration, but reduces the amplitude of periodic drag variation. The side force was found to be highly unsteady depending on flow conditions, and its azimuth-averaged value can change sign with Reynolds number. The torque required to drive the hub increased with rotation speed and freestream speed, and is found to be of the same order as that expected from the drag difference between shanks on the advancing and retreating sides. The azimuth-resolved force and torque data suggests that transient torque values peak at certain portions of the azimuth that slightly lead those of highest drag. The total power demand attributed to the hub is still mostly due to drag. Scaling to vehicle flight speed and size should improve this approximation, unless interactions with pylons, nacelles or other components cause asymmetries sufficient to change the result. In addition to aerodynamic loads measurement, the unsteady wake of the rotating hub was measured using constant temperature anemometry technique. Wavelet transforms in addition to Fourier transforms are used to characterize the unsteady wake. A clear asymmetry is observed in the 4/rev energy content of the hub wake.
Nonlinear Model Predictive Tracking Control for Nonholonomic AGV Based on Bio-Inspired Neurodynamics
Authors: Yin Xiao-Hong , Yang Can
Published: April 2014

Considering nonholonomic constraint and input saturation of the Automatic Guided Vehicle (AGV) kinematic model, in the present work the nonlinear model predictive control was applied and a combined tracking/stability control approach was proposed. In addition, the bio-inspired neurodynamics model was applied to generate smooth forward velocities so that the sharp velocity jump can be overcome by the proposed controller. Specifically, an optimal sub-control method consisting of cost function and constraints were obtained based on the model predictive control principle, and a terminal sub-control method was designed to make the control system stable. Finally, the effectiveness of the proposed control strategy was demonstrated through comparison studies with simulations.
Prediction of Thermal Conductivity and Shear Viscosity of Water-Cu Nanofluids Using Equilibrium Molecular Dynamics
Authors: Akıner Tolga , Ertürk Hakan , Atalık Kunt
Published: April 2014

Nanofluids are new class of fluids which can be used for many engineering applications due to their enhanced thermal properties. The macroscopic modeling tools used for flow simulations usually rely on effective thermal and rheological properties of the nanofluids that can be predicted through various effective medium theories. As these theories significantly under-predict, using correlations based on experimental data is considered as the only reliable means for prediction of these effective properties. However, the behavior might change significantly once the particle material or base fluid change due to different particle fluid interactions in the molecular level. One of the most promising means of modeling effective properties of the nanofluids is the molecular dynamics simulations where all the intermolecular effects can be modeled. This study investigates equilibrium molecular dynamics simulation of the water-Cu nanofluids to predict the thermal and rheological properties. The molecular dynamics simulation is carried out to achieve a thermodynamic equilibrium, based on a state that is defined by targeted thermodynamic properties of the system. The Green-Kubo method is used to predict the thermal conductivity and viscosity of the system. The study considers the use of different combining rules such as Lorentz-Berthelot and sixth-power rules for defining the inter-atomic potentials for water modeled by SPC/E and nanoparticles modeled by Lennard-Jones potential. The predicted effective properties that are thermal conductivity and shear viscosity are then compared with experimental data from literature. The predicted transport properties at different temperatures and particle concentrations are compared to experimental data from literature for model validation.
Feature Selection in Evolutionary Algorithm-Based Parameter Estimation of Duffing Oscillators
Authors: Banerjee Amit , Mahfouz Issam Abu , Abu-Ayyad Ma’moun
Published: April 2014

The use of evolutionary optimization techniques such as genetic algorithms, differential evolution, swarm optimization and genetic programming to solve the inverse problem of parameter estimation for nonlinear chaotic systems has been gaining popularity in recent years. The efficacy of such evolutionary schemes depends on the definition of a suitable fitness function which is used to compare potential solutions in the population. In almost all research involving evolutionary schemes for parameter identification, displacement values of the first few hundred Poincaré points, after ignoring transient effects, have been used as the feature set. The measured response of the system is compared to the response of the potential solutions in the population over these Poincaré points, although there is no empirical research to show that such a feature set works better than other possible feature sets. In this paper, a smaller feature set based on first and second-order statistical parameters of the response are considered and the estimation results are compared to the estimate produced by using the standard Poincaré points-based feature set, called the finite sample feature set in this paper. Also compared are results using three evolutionary algorithms — firefly algorithm, particle swarm optimization and differential evolution. It has been shown that the proposed feature set converges to a near-optimal solution faster and in fewer generations and produces estimates that are comparable to those obtained with the finite sample feature set.
Steepest-Entropy-Ascent Quantum Thermodynamic Non-Equilibrium Modeling of Decoherence of a Composite System of Two Interacting Spin-½ Systems
Authors: Cano-Andrade Sergio , von Spakovsky Michael R. , Beretta Gian Paolo
Published: April 2014

The equation of motion of steepest-entropy-ascent quantum thermodynamics (SEA-QT) was first postulated in the early 1980s with the intent of modeling the non-linear dynamic behavior encountered in nature, which the unitary (linear) dynamics of the Schrödinger-von Neumann equation cannot. The SEA-QT equation is used here to model the decoherence phenomenon between two distinguishable and indivisible elementary constituents of type spin–½ (e.g., quantum bits or qubits). The resulting set of non-linear, first-order differential equations is solved with a fourth-order-Runge-Kutta routine provided by Matlab®. The time evolution of the state of the composite system as well as that of the reduced and locally-perceived states of the two constituents are traced from an initial non-equilibrium state of the composite along its relaxation towards stable equilibrium at constant system energy. An entangled and generally coherent, initial non-equilibrium state of the composite quantum system is prepared using a heuristic approach, which consists of randomly and homogeneously generating an initial point on the Bloch sphere for each of the constituents and then using a weighted average of their projections to arrive at an initial state for the composite. Results show how the initial entanglement and coherence between the two spin–½ constituents are reduced during relaxation towards a state of stable equilibrium. When the two particles are non-interacting, the initial coherence is lost once stable equilibrium is reached. When they are interacting, the coherence in the final stable equilibrium state is only that due to the interaction.
Design of an Ingestible Capsule With Wireless Communication and Powering Function for Obesity Treating
Authors: Yan Liang , Wang Tianyi , Jiao Zongxia , Peng Juanjuan
Published: April 2014

Intra-gastric balloons have been and effective and non-invasive method for morbid obesity treating since it is proposed. However, traditional balloons lead to complications such as nausea and sickness caused by insertion and removal endoscopes. Despite free of endoscope-guide insertion and removal process, wireless controlled balloons still have to face the problem of energy shortage. This paper proposes a novel wireless controlled and powered endoscope capsule of edible size. The performance of wireless control and powering are tested respectively. In addition, in-vivo and in-vitro experiments are conducted for further evaluation and shows feasibility for treating morbid obesity. This study may contribute to the development of endoscopic devices and surgery as well.