bluuebunny/crossref_metadata_2025 huggingface dataset:
Finish Processing Support System via Grinding Force Control Based on Hand Stiffness Estimation
Authors: Kawaguchi Tomoyuki , Yano Ken’ichi , Osada Tsuginobu , Matsui Hirokazu , Sakito Daiki , Fofana Mustapha S.
Published: October 2013

Compared with machining by automation, handwork is suitable for high-variety low-volume manufacturing, because such manufacturing requires a lower cost and shorter lead time. However, high-concentration machining should be implemented in handwork. Furthermore, any mistake generated by disturbance from tool rotation results in useless products and wasted materials. Our goal was to develop a finish machining support system that can realize high-accuracy machining in the case of tool rotational direction orthogonal to the feed direction without any machining mistakes. Specifically, in this study we developed a fixture-type machining support robot with a parallel link system to achieve good usability and highly accurate machining. We estimate the operator’s hand stiffness from the machining force and end effector position during grinding, and then the grinding force is controlled based on estimation of the worker’s hand stiffness. As a result, the influence of grinding force on the worker’s hand is suppressed, and the problems with machining accuracy in handwork are lessened. Finally, the effectiveness of the proposed method is shown by grinding experiments.
Effect of Dopant Element on the Strength and Reliability of Ni-Base Superalloy at High Temperatures
Authors: Sano Tomohiro , Suzuki Ken , Miura Hideo
Published: October 2013

In order to assure the reliability of advanced gas turbine systems, it is very important to evaluate the damage of high temperature materials such as Ni-base superalloys under creep and fatigue conditions quantitatively. The mechanism of the directional coarsening (rafting) of the γ′ phase (Ni3Al) of Ni-base superalloys under uni-axial strain at high temperatures was analyzed by molecular dynamics (MD) analysis. The strain-induced anisotropic diffusion of Al atoms perpendicular to the interface between the γ′ phase and the γ phase (Ni-matrix) was observed clearly at a Ni(001)/Ni3Al(001) interface. The strain-induced anisotropic diffusion was validated by the experiment using the stacked thin film structures with the (001) face-centered cubic (FCC) interface. The reduction of the diffusion of Al atoms perpendicular to the interface is thus, effective for improving the creep and fatigue resistance of the alloy. It was found by MD analysis that palladium was one of the most effective elements that restrain Al atoms from moving around the interface under the applied stress. The presence of the interaction between the different dopant elements was also clarified.
Anisotropic Strain-Field-Induced Change of the Electronic Conductivity of Graphene Sheets and Carbon Nanotubes
Authors: Ohnishi Masato , Kawakami Hiroshi , Suzuki Yusuke , Suzuki Ken , Miura Hideo
Published: October 2013

Since the discovery of carbon nanotubes (CNTs), there have been many efforts to develop various electronic devices and sensors. The authors have also validated the possibility of a highly sensitive strain sensor using popular resin in which multi-walled CNTs (MWNTs) were dispersed uniformly. It is, however, indispensable for clarifying how to change the electronic state of a deformed CNT for assuring the stable performance of the sensor because the reported sensitivity has ranged widely. In this study, the relationship between the deformation characteristic of a CNT under strain and its electronic conductivity was analyzed quantitatively. The analysis result obtained from density functional theory (DFT) calculation showed that the orbital hybridization was occured when the local curvature exceeded about 0.3 Å−1, inducing the decrease in the band gap. Based on the analytical results, a two-dimensional strain sensor was developed by applying buckling deformation-induced conductivity change of MWNTs by using MEMS technology.
Effect of Silicon Content of Aluminum Alloy 6351 in Turning Process
Authors: da Cunha Daniel Fernandes , da Silva Marcio Bacci
Published: October 2013

The machinability of three commercial samples of the 6351 aluminum alloy with different silicon content was investigated in this work. Several parameters were used to evaluate the machinability in turning process, including the quality of the machined surface and cutting force. A design of experiments with three levels was used focusing on low values of feed rate (0.10, 0.15 and 0.2 mm/rev). The other parameters involved were: depth of cut (1.0, 1.5 and 2.0 mm), the silicon content (1.1, 1.2 and 1.3%) and two sets of cutting speed, one in the build up edge region (80, 100 and 120 m/min) and the other in a built up edge free region (200, 600 and 1000 m/min). The surface roughness parameter evaluated was Rq. A second design of experiment with three levels using higher values of feed rate (0.2, 0.35 and 0.5 mm/rev) and depth of cut of 2.0 mm was used to evaluate the influence of the silicon content in the cutting force. The effect of cutting fluid (dry machining, minimum quantity of fluid and over head cooling) was also analyzed. The results show that the silicon content has influence on the surface roughness. The statistical model in the build up edge region explains 79.95% of the total variation of roughness and 99% for cutting forces, for the other region this value is 81.99% for surface roughness and 98.96% for cutting force. The diameter of the workpiece has an influence on the results because the variation of hardness.
Analysis of Aeroelastic System Under Random Gust With Parametric Uncertainties Using Polynomial Chaos Expansion
Authors: Venkatesh S. , Sarkar Sunetra , Desai Ajit
Published: October 2013

In the design of wind turbine structures, aeroelastic stability is of utmost importance. It becomes even more crucial when there are uncertainties involved in it. A symmetric airfoil with its pitch-plunge flexibility is considered under potential flow. The potential flow model is justified as the classical flutter model involves unseparated flow over the body so that inviscid assumptions are valid. In the present study of aeroelastic system, nonlinear parameters have been considered as it can stabilize the diverging growth of a flutter oscillation. Quantification of aleatoric uncertainties present in the system has been done by modeling them as a Gaussian parameters. The epistemic uncertainty present in the system has also been reduced by considering unsteady vortex lattice method (UVLM) instead of the rigid wake model of Wagner. In this model, the wake is free to evolve and also the shape of airfoil has been considered. The present study involves usage of UVLM code on a NACA 0012 airfoil. The values of the linear flutter speed predicted by using UVLM code is in close agreement with that of the fixed wake model of Lee et al. When the structural nonlinearities are present, the system exhibits a self sustained oscillation of constant amplitude called as Limit Cycle Oscillation (LCO) even beyond the linear flutter speed. In the present study, a horizontal gust is modeled with a given spectra by superposition of a set of sinusoidal components which is a standard practice. This gust has then been applied on the airfoil along with the structural uncertainties. A spectral uncertainty quantification tool called Polynomial Chaos Expansion is used to quantify the effect of uncertainty propagation and calculate the response statistics. A non-intrusive version of the method using stochastic projection approach is used to capture the time histories and plot the PDFs at various time instants of all the realizations with Monte Carlo Simulation as a reference solution. The evolution of PCE coefficients in the time domain along with its ensemble variations has also been looked into in the present study.
A Framework for Enhancing Outside-the-Box Thinking in Engineering Design, Demonstrated on a Case Study
Authors: Roser Holger M. , Dartnall W. John
Published: October 2013

This paper introduces a framework for enhancing creative thinking in engineering design. As a flexible methodology, the proposed Creative Engineering Design (CED) framework integrates a new concept development tool, the Concept Assessment Taxonomy (CAT), which constitutes the core of the proposed methodology. By combining the procedures of concept generation, evaluation and selection in a single matrix, the CAT aims to systematize and simplify the overall conceptualization process, while delivering design process transparency.

Early trials have shown the effectiveness of the CED framework in offering procedural guidance and a better comprehension of the multifaceted nature of engineering design. It complements well-established textbook-methods in an effort to reduce ad-hoc and trial-and-error approaches, while minimizing decision-making based on intuition and guesswork.

In order to demonstrate its usefulness within a real world context, the proposed methodology is applied to a case study in the field of mechanical design: a new mechanical fuel injection system capable of curbing small engine emissions.
The Influence of Piezo-Viscous Lubricants on EHL Line and Point Contact Problems
Authors: D’Agostino V. , Petrone V. , Senatore A.
Published: October 2013

A good and accurate prediction of the elastohydrodynamic lubrication behaviour requires consideration of the constitutive equation for the lubricant. In particular, for applications involving synthetic oils or mineral oil with polymeric additives that exhibit shear-thinning behaviour, the use of an appropriate pressure-viscosity relationship for the lubricant is required to predict the EHL behaviour more accurately [1–3]. For this reason, this paper aims to emphasize the importance of implementing piezo-viscous models with accurate treatment methods in EHL applications. Due to the high pressure in an EHL contact, in fact, the elastic deformation of the surfaces and pressure dependence of viscosity play the pivotal role and in many applications, the lubricant exhibits a shear-thinning behaviour which significantly affects the film thickness [4–6]. The effects of different pressure–viscosity relationships, including the exponential model, the Roelands’ model and specifically, the Doolittle model are investigated and a generalized formulation that can efficiently treat shear-thinning fluids with provision for compressibility in the EHL contact is presented.

In the light of above facts, models for 1D and 2D EHL contacts for simulating the behaviour of the pressure distribution and the shape of the film thickness using a generalized Reynolds equation and shear-thinning fluids is developed. In particular for EHL 2D problem a more accurate full multigrid approach has been used and both the analysis is based upon the assumptions of isothermal condition. In this work, in fact, we show that the piezo-viscous rheology of the lubricant plays an important role in determining the value of pressure peaks. Pressure profiles and film shapes are showed and variations of the minimum and central film thickness with dimensionless parameters are also presented. It is found that the real pressure–viscosity behaviour predicted by the free-volume model yields a higher viscosity at the low-pressure area which results in a larger central film thickness. Therefore, due to use of the free-volume model, the presented results are more consistent with literature experimental observations and the Doolittle model effectively predicts the film thickness that closely matches experiments and properly characterizes the behaviour of shear-thinning lubricants.
Fault Diagnosis of Reciprocating Compressor Valve Using Acoustic Emission
Authors: Wang Y. F. , Peng X. Y.
Published: October 2013

The faults of a reciprocating compressor valve can be diagnosed using the acoustic emission. Four typical valve faults including the crack, rupture and deformation in the valve discs and leakage through the flow passage were investigated. The fault features were extracted by comparing the acoustic emission signals from the failed valves with those from the normal valves. The results show that the feature locations where the discharge valve opened and closed could easily be identified by the envelope waveform of acoustic emission signal, and they changed when the valve failed including the rupture and deformation in valve discs and leakage through the flow passage and changed with the variation of the discharge pressure. The extent to which the valve failed could be estimated by the deviation degree between the opening/closing locations and the standard ones. The leakage caused by these valve faults could also lead to the increase in the amplitude of the acoustic emission wave. However, the fault of crack in valve disc couldn’t be identified by acoustic emission signal effectively.
Novel Turbine Endwall Contours for the Reduction of Heat Transfer Generated Using the Ice Formation Method
Authors: Haase Kristian , Winkler Sven , Weigand Bernhard , Neumann Sven Olaf
Published: October 2013

Three-dimensional contouring of vane endwalls has proven to be an efficient method for reducing aerodynamic losses or, respectively, endwall heat transfer by active manipulation of the complex vortical flow structures in the vane passage. The present study shows the application of the Ice Formation Method for endwall contouring of a guide vane row with the goal of reducing endwall heat transfer. Endwall contours for the guide vane row of a low pressure turbine are experimentally generated in form of ice contours and evaluated with respect to their heat transfer behavior. A comparison with the flat plate showed that average heat transfer is considerably reduced for the ice-contoured endwalls with reductions up to 42%. The generated endwall contours were also digitized and used in numerical simulations. The latter allowed for a comparison of endwall heat transfer for the novel contours with the heat transfer for a flat, uncontoured endwall. This showed that the new endwall contours also feature decreased average heat transfer compared to the flat endwall with the maximum obtained reduction being 12%.
Assessment of Geometry Reconstruction Techniques for the Simulation of Non-Classical Aileron Buzz
Authors: Fusi Francesca , Romanelli Giulio , Guardone Alberto , Quaranta Giuseppe
Published: October 2013

A computational study of non-classical aileron buzz is presented, which focuses on computational grid details for accurate simulations of this type of nonlinear transonic phenomenon. The analysis points out that mesh refinement is crucial to obtain reliable results and that the choice between a smoothed and non-smoothed geometry has an influence on the system response, both quantitatively and qualitatively. As a matter of fact, grid details affect the simulation of shock dynamics, which is the driving mechanism for non-classical aileron buzz.
Interactive Ram Pump Display Project
Authors: Celik Emine
Published: October 2013

During a senior level thermal system design class given at York College of Pennsylvania, a customer-based design project has been implemented. This project provides the students with the opportunity to apply the knowledge that they learned in class and allows them to think creatively to achieve the given task. For this project, students are required to prepare a project proposal based on the needs of the customer and deliver a written report at the end of the semester. The main purpose of the project is to design an interactive museum display to show the working principle of a ram pump for the York County Heritage Trust Museum. The hydraulic ram pump utilizes the power of flowing water to operate without the use of electricity. The project requires students to apply energy and cost analysis. This paper presents the details of the design requirements, procedures and the final design. Examples of student work and the assessment of the work are also provided.
A Numerical Study of Flow and Temperature Maldistribution in a Parallel Microchannel System for Heat Removal in Microelectronic Devices
Authors: Siva Manoj , Pattamatta Arvind , Das Sarit Kumar
Published: October 2013

A common assumption in basic heat exchanger design theory is that fluid is distributed uniformly at the inlet of the exchanger on each fluid side and throughout the core. However in reality, uniform flow distribution is never achieved in a heat exchanger and is referred to as flow maldistribution. Flow maldistribution is generally well understood for the macrochannel system. But it is still unclear whether the assumptions underlying the flow distribution in conventional macrochannel heat exchangers hold good for microchannel system. In this regard, extensive numerical simulations are carried out in a ‘U’ type parallel micro-channel system in order to study flow and heat transfer maldistribution and validated with in-house experimental data. A detailed parametric analysis is carried out to characterize flow maldistribution in a microchannel system and to study the effect of geometrical factors such as number of channels, n, Area of cross section of the channel Ac, manifold cross section area Ap, and flow parameter such as Reynolds number, Re, on the pressure and temperature distribution. In order to minimize the variation in pressure and to reduce temperature hot spots in the microchannel, a Response surface based surrogate approximation (RSA) and a gradient based search algorithm are used to arrive at the best configuration of microchannel cooling system. A three level factorial design involving three parameters namely Ac/Ap, Re, n are considered. The results from the optimization indicate that the case of n = 5, Ac/Ap = 0.12, and Re = 100 is the best possible configuration to alleviate flow maldistribution and hotspot formation in microchannel cooling system.
Aging Mechanism of Welded Joints of P92 Steels
Authors: Huang Changzheng , Guo Cliff Yi , Liang Jun , Du Jinfeng
Published: October 2013

This paper concerns the study of aging mechanism of welded joints of P92 steels. Alloys like P92 steel are commonly used in ultra-supercritical (USC) power plants. Depending on the service conditions, the welded joints may become a critical weak link between component connections, showing crack openings and even failures. In this study, the long-term aging effect on the welded joints of P92 steels was investigated under the expected service temperature of 650°C. Microscopic analysis showed that under normal heat treatment, a weld joint has martensitic micro-structure with carbide particles of size 0.1∼0.2μm distributed along grain boundaries. After aging 1000h, white deposits are seen to precipitate from the grain and lath boundaries. Further aging makes these deposits to grow bigger and denser. After 7000h, the Laves phase may grow up to 1μm, causing the material to weaken and fail.
Combat Robot Strategy Adaptation Using Multiple Learning Agents
Authors: Recchia Thomas , Chung Jae , Pochiraju Kishore
Published: October 2013

As robotic systems become more prevalent, it is highly desirable for them to be able to operate in highly dynamic environments. A common approach is to use reinforcement learning to allow an agent controlling the robot to learn and adapt its behavior based on a reward function. This paper presents a novel multi-agent system that cooperates to control a single robot battle tank in a melee battle scenario, with no prior knowledge of its opponents’ strategies. The agents learn through reinforcement learning, and are loosely coupled by their reward functions. Each agent controls a different aspect of the robot’s behavior. In addition, the problem of delayed reward is addressed through a time-averaged reward applied to several sequential actions at once. This system was evaluated in a simulated melee combat scenario and was shown to learn to improve its performance over time. This was accomplished by each agent learning to pick specific battle strategies for each different opponent it faced.
Effect of Viscosity Ratio on the Electric-Field-Driven Enhancement of Heat/Mass Transfer to a Spherical Drop
Authors: Abdelaal Mohamed R. , Jog Milind A.
Published: October 2013

The effect of viscosity ratio on the electric-field-driven enhancement of heat/mass transfer to a spherical liquid drop of one dielectric fluid from another immiscible dielectric fluid is computationally investigated in this paper. The flow field is considered to be in the Stokes regime and the energy (species) conservation equations in the continuous phase are solved numerically using a fully implicit finite volume method. Results for flow outside the drop, transient temperature distributions, Nusselt number variations, and heat/mass transfer enhancement are presented for Peclet numbers varying from 10 to 500, dimensionless electric field frequency from 50 to 1000, and the ratio of viscosity of the continuous to the dispersed phase varying from 0.1 to 50. Steady and non-uniform unsteady electric fields are considered. The computational simulations show that when viscosity of the drop is lower than the viscosity of the surrounding fluid, a steady uniform electric field is more effective in enhancement of heat/mass transport compared to a non-uniform time periodic electric field. Conversely, when the continuous phase is less viscous than the drop, the non-uniform time periodic electric field provides improved heat/mass transport than the steady uniform electric field.
Deviational Phonons and Thermal Transport at the Nanoscale
Authors: Péraud Jean-Philippe M. , Hadjiconstantinou Nicolas G.
Published: October 2013

We present a new method for simulating phonon transport at the nanoscale. The proposed approach is based on the recently developed energy-based deviational Monte Carlo method by the authors [Phys. Rev. B 84, 205331, 2011] which achieves significantly reduced statistical uncertainty compared to standard Monte Carlo methods by simulating only the deviation from equilibrium. Here, we show that under linearized conditions (small temperature differences) the trajectories of individual particles simulating the deviation from equilibrium can be decoupled and can thus be simulated independently, without introducing any additional approximation. This leads to a particularly simple and efficient simulation method that can be used to treat steady and transient phonon transport problems in arbitrary three-dimensional geometries.
A Comprehensive Algorithm for the Analysis of ECG Waveforms
Authors: Palliyali Abdul Jaleel , Tafreshi Reza , Mohsin Nasreen , Tafreshi Leyla
Published: October 2013

This paper presents a comprehensive approach for the detailed analysis of ECG waveforms including various morphologies to aid clinical diagnosis. Clinical judgment is often based on observing various features which may occur simultaneously on the ECG. Thus, to automate diagnosis, a comprehensive tool capable of detecting all these features is required.

Parabolic curve fitting, adaptive thresholds and synchronicity across leads are utilized to detect the various waves of the QRS complex namely Q,R,S,R’ and S’. Onset of the QRS complex and the J point are detected using a ‘modified second derivative’ approach. The isoelectric level is detected using linearity and slope conditions. P and T waves are detected using ‘area under curve’ approach. Measurements such as peak-to-peak intervals and ST elevation/depression are numerically calculated from the points obtained. Curve fitting and change in slope are utilized for obtaining morphology of the ST segment. Presence of significant Q waves and abnormal T waves are inferred using clinical guidelines and numerical calculations.

The performance of the algorithm is validated on 40 sample patient data — 20 healthy and 20 with Myocardial Infarction. Average accuracy shown in detecting all points of interest is 98.5%. All measurements are successfully calculated from these points. Along with this reliable performance, the approach proves to be simple and computationally fast.
Hydrogen Production Potential and Cost of Wind-Hydrogen Hybrid Energy System
Authors: Çelik Muhammet , Genç Gamze , Genç M. Serdar , Yapıcı Hüseyin
Published: October 2013

Main aim of this study is to investigate annual wind power output, annual hydrogen production quantity and hydrogen production cost of wind-hydrogen energy system in the Pinarbasi-Kayseri region in Turkey which has remarkable wind potential in the central region of Turkey. Turkish State Meteorological Service (TSMS) measured the value of mean wind speed of Pinarbasi as 3.67 m/s above 10m ground between 2000 and 2006 years. In this study, three different hub heights (50m, 80m and 100m) were considered, and so the measured mean wind speed at 10m was extrapolated to considered heights and annual wind power output was calculated. Four different turbine rated powers (800kW, 900kW, 2000kW and 3000 kW) and two different electrolyser powers (120kW and 40kW) for hydrogen production were assumed. Levelised cost of electricity method was used in order to determine the cost analysis of wind energy and hydrogen production. The results of this study bring out clearly the variation of potential of hydrogen production and cost with wind speed, wind turbine hub height and wind turbine rated power and electrolyser power.
Air Handling Unit Level Fault Signature Development Using EnergyPlus
Authors: Song Li , Branesky Briana
Published: October 2013

In the effort to create more energy efficient buildings, an effective fault detection process must be developed for monitoring and diagnosing malfunctions in the Heating Ventilation and Air Conditioning (HVAC) system. This study provides energy loss signatures that can be used to diagnose a specific faulty component at the unit level. An analysis has been performed on a single air handling unit (AHU) to determine how faulty HVAC components effect the overall energy consumption of the unit.

To begin the process, the Engineering Laboratory building on the campus of the University of Oklahoma was modeled for the simulation, using EnergyPlus 7.0, Google Sketchup 8, and OpenStudio 0.6.0. The building has an existing single duct system with a 3hp AHU with a forward curved fan that discharges 2500 cfm (1.175 m3/s) that covers approximately 2809 square feet (261 m2). Inputs into the simulation included building constructions, architecture, internal loads, and external loads from weather, sun, and shade objects. Simulations were run using the stated software, and a base case was established for energy consumption. Next, components and variables on the AHU, such as minimum outside air intake, economizer outside damper control, cooling coil valve, duct work pressurization, and various sensors were individually modified to reflect a malfunction or inefficiency. The energy loss caused from these changes in inputs was quantified and analyzed for the purpose of establishing a graphical range of energy loss signatures associated with each faulty component. Building Engineers and operators will be able to not only detect the exact malfunction faster, but also to ascertain the associated energy loss cost associated with the fault. The results of the study will be used to automate an online energy monitoring fault detection and diagnosis process.
Thermal Effects in Slider Bearings With Limited Corrugation and Power-Law Lubricant
Authors: Huynh B. P.
Published: October 2013

Influence of temperature on the performance of slider bearings of infinite width but having corrugation of limited extent is investigated numerically, using a commercial Computational Fluid Dynamics (CFD) software package. Lubricant is assumed to be a fluid of power-law type with temperature-dependent viscosity. Over a range of the power-law index, combined effects of temperature and the corrugated section’s location on load-supporting capacity Fy of the bearing’s fluid film are considered. Influence of the bearing-gap surfaces’ thermal boundary condition is also examined. Compared with isothermal situation, thermal effects result in significant reduction in Fy, especially with shear-thickening lubricants. This reduction in Fy is also affected significantly by the corrugated section’s location.
Controller to Regulate Maximum Server CPU Temperatures in a Rack by Varying CRAC Supply Air Temperatures
Authors: Sundaralingam Vikneshan , Joshi Yogendra , Arghode Vaibhav
Published: October 2013

Conventionally, raised floor data centers operate using controllers that only maintain constant data center space conditions (i.e. supply air temperatures or return air temperatures) at the Computer Room Air Conditioning (CRAC) Unit level with the intention of providing enough cooling for the servers. The objective of this paper is to explore the framework required to design a controller that regulates server CPU temperatures by specifying the supply air temperature of the CRAC. The controller will be an addition to the existing controller used by the CRAC to regulate supply air temperatures. In the discrete-time domain, implementation and the performance of the modified integral action controller is analyzed and other important parameters are compared. As a preliminary attempt, the controller will be designed for a standard 44U cabinet with 42 “1U” servers, where the machines will execute a prescribed compute load variation: (1) step increase in all compute loads and (2) scaled down representation for a rack of servers using utilization trends from one of Google’s data centers. Ultimately, the development of this controller is motivated by the growing interest in Data Center Infrastructure Management (DCIM) where the IT level and facility level information are both used to intelligently plan and manage resources of a data center.
Microfluidic Cell Co-Culture Platform With Liquid Fluorocarbon as the Cell Separator
Authors: Brewer Bryson M. , Shi Mingjian , Gao Yandong , Webb Donna J. , Edd Jon F. , Li Deyu
Published: October 2013

Cell co-culture platforms are essential tools for investigating inter-cellular communication and cellular activities among different cell populations. Microfluidic cell co-culture platforms offer several advantages over their conventional counterparts, including precise control over the cellular microenvironment, low cost, and high throughput. Previously, we have developed microfluidic devices using a hydraulically/pneumatically controlled polydimethylsiloxane (PDMS) valve barrier to separate distinct cell populations in culture, providing a means for manipulation and specific treatment of each cell type with different reagents [1]. After releasing the barrier, different cell populations can interact with each other while being observed using real-time imaging. However, the solid PDMS valve barrier is not truly reversible, as any cells/cell processes underneath the barrier will likely undergo physical damage when the valve barrier is activated.
Vehicle Weight Distribution and Occupant Loadings
Authors: Arndt Mark W.
Published: October 2013

The Federal Aviation Administration (FAA), Federal Transit Authority (FTA) and Coast Guard instituted or recently proposed an increase in the average passenger weight used to calculate load and conduct safety analysis and tests in multiple modes of transportation. The increased passenger weight requirements were created in response to the Center for Disease Control’s (CDC) documented rise in weight among the country’s citizens and followed crash or failure incidents in which a cause was overweight equipment. The current certification requirements under CFR 49, Part 567 state that Gross Vehicle Weight Rating (GVWR) of a motor vehicle shall not be less than the sum of the unloaded vehicle weight, rated cargo weight and 150 pounds times the number of designated seating positions. Actual occupant weight distributions versus certified weight per occupant seat causes a potential conflict between a vehicle’s in-use weight versus its certified GVWR. This paper is distinct in its contrasting of the 150 pound occupant standard in relation to documented actual occupant weight, clothing, personal items and baggage. A midsized bus example was used to explore the statistical probability that adult passengers and rated cargo would result in weight distributions that exceeded tire load capability, Gross Axle Weight Rating (GAWR), or GVWR. The unreliability of the 150 pounds per designated seat position in producing loaded weight under gross weight ratings was demonstrated for a midsized bus. Results demonstrated that load conditions and usage restrictions are identifiable and decrease the probability of operating in a condition that exceeds a weight rating. Weight assumptions that take into consideration well documented transportation industries baggage weight were identified as potentially confounding additional weight that may contribute to overload of midsized buses.
Radiative Heat Transfer Modeling Using the CW and SLW Models in Gas Mixtures With Soot
Authors: Cassol Fabiano , Brittes Rogério , França Francis Henrique Ramos , Ezekoye Ofodike A.
Published: October 2013

This paper presents the computation of radiative heat transfer in a slab filled with a participating medium composed of CO2, H2O, and soot. The HITEMP 2010 spectral database is employed to obtain the necessary parameters for the prediction of radiative transfer in the non-isothermal, homogeneous medium. The spectral integration is performed with the spectral line weighted-sum-of-gray-gases (SLW) and the cumulative wavenumber (CW) models and compared with the line-by-line (LBL) benchmark solution. Since radiation heat transfer can sometimes be the dominant heat transfer mechanism in combustion processes, it is important to understand how the predicted thermochemical state depends on the radiation model for the composition, taking into account the complex dependence of the properties with the spectrum. The contribution of this work is to compare two detailed spectral model that are available in the literature and determine advantages and disadvantages in some practical, illustrative examples.
How to Design and Create a Cardan Shaft for a Single Port Robot by Selective Laser Sintering
Authors: Roppenecker Daniel B. , Traeger Mattias F. , Gumprecht Jan D. J. , Lueth Tim C.
Published: October 2013

With the spread of endoscopic interventions the postoperative stress for patients has been reduced clearly. These interventions through natural orifices of the body (Natural orifice transluminal endoscopic surgery: NOTES) need miniaturized instruments with high precision, high range of motion and a high force load transmission.

Our aim is to develop a mechatronic, single-port robotic system to guide and move flexible endoscopic instruments and optics inside the body. The system should be adapted to a flexible endoscope and consists of two flexible and actuated end-effectors that carry and manipulate flexible instruments. Due to the flexible end of the structure, laparoscopic single-port surgery through one incision and endoscopic surgery through a natural orifice would be possible. The concepts and prototypes were realized by selective laser sintering (SLS). One way to create flexible structures for a single use robot is to use universal joints assembled together in series. Next, selective laser sintering can now print these parts with the joints already assembled, in one part. There is no need for assembling or adhesive bonding. The final step is to replace the real joints of the cardan shafts with elastic joints.

The proposed joints are made by the powder PA 2200 based on nylon. This basic powder is certificated as biocompatible according to ISO 10993-1. The challenge in this new field of printed medical robotics is to define a manufacturing process that enables you to design a part, create it by SLS and get it approved as a medical product.
Measurement of the Intrinsic Thermal Conductivity of Individual Silicon Nanoribbons
Authors: Yang Yang , Li Deyu , Jiang Youfei , Guan Zhe , Xu Terry T. , Yang Juekuan
Published: October 2013

One-dimensional semiconductor nanowires, which show strong size dependent properties, have attracted significant attention during the past decade. The small characteristic size and unique physical properties can lead to broad applications such as nanoelectronics, photonics, and energy conversion. As the most widely used semiconductor material, silicon nanostructures (e.g. Si nanowires/nanoribbons) have drawn a lot of interest. Significant amount of efforts have been taken to understand their thermal properties. Experimentally, there have been a few reports on the thermal conductivity (κ) of individual 1D silicon nanostructures. Li et al. [1] first acquired the thermal conductivity of individual Si nanowires of different diameters. Later, the thermal conductivity of thin Si nanowires [2] and rough Si nanowires [3] has been measured using the same techniques. However, in these studies, the measured thermal conductivity is an effective one, which includes the effects of the contact thermal resistance between the Si nanowire and the heat source/sink. These effects will lead to some uncertainties in the experimental data.
A Polymer-Based Microfluidic Resistive Sensor for Detecting Distributed Loads
Authors: Gu Wenting , Cheng Peng , Ghosh Arindam , Liao Yuxi , Liao Boxiong , Beskok Ali , Hao Zhili
Published: October 2013

This paper reports on a polymer-based microfluidic resistive sensor for detecting distributed loads. The sensor is comprised of a polymer rectangular microstructure with an embedded electrolyte-filled microchannel and an array of electrodes aligned along the microchannel length. Electrolyte solution in the microchannel serves as impedance transduction. Distributed loads acting on the polymer microstructure give rise to different deflection along the microstructure length, which is recorded as the resistance change in electrolyte solution. This sensor can detect distributed loads by monitoring the resistance change at each pair of electrodes. A sensor with an in-plane dimension of ∼20mm×10mm and five pairs of electrodes is fabricated using a CNC machine. 1M KCl solution is used as the electrolyte. Using a custom built electronic circuit on breadboard and a custom LabVIEW program, the static and dynamic performance of the sensor is characterized, demonstrating the feasibility of employing this sensor to detect distributed loads.
Continuum Manipulator Statics Based on the Principle of Virtual Work
Authors: Rone William S. , Ben-Tzvi Pinhas
Published: October 2013

This paper presents a generalized method of determining the static shape conformation of a continuum robot based on the principle of virtual work. A lumped parameter model is utilized to model a prototypical single-segment manipulator. Elastic effects, gravitational forces and actuation loading are modeled as generalized forces and moments acting along the manipulators at discrete masses. A brief derivation of the governing static equations based on the principle of virtual work is presented, and then applied to the problem of continuum manipulator statics. The numerical method was successfully implemented numerically, capable of determining a system’s static equilibrium given a prescribed actuation.
A Numerical Investigation on a Flow of a Viscous Oil Drop in Water Inside a Small Diameter Capillary Tube
Authors: Joshi Harsh , Dai Liming
Published: October 2013

This paper reports the findings of a two dimensional numerical CFD simulation of a two phase immiscible flow. The results of the simulations are validated by use of theoretical equations and comparisons to published experimental results. From the computational results, we show how the water film thickness surrounding the oil drop changes with capillary number and how the transient pressure profile changes with velocity. It is shown how a numerical simulation can provide accurate details of a flow that is hard to simulate and visualize in an experiment. We provide a pressure Vs Time data obtained from the simulation which shows the wetting film of water reduces the required pressure drop. It is seen that a presence of a water film makes it easier for the oil drop to move under a lower pressure. This study will be helpful in comparing the vibrational effect on oil drop mobilization because it is expected the pressure required after vibrational stimulation will fall between the maximum pressure without water film and minimum pressure with water film.
Novel Fabrication and Characterization of Diaphragm Micromirror Using ‘Bulk Lithography’
Authors: Gandhi Prasanna , Kamble Shital , Bhole Kiran
Published: October 2013

Adaptive optics is being explored actively for several applications such as wavefront correction in biomedical imaging (retinal surgery), variable focal length lenses, and adaptive zoom micromirrors. Diaphragm micromirrors have several advantages such as continuity in image and ease of fabrication. This paper investigates, for the first time to the best of our knowledge, fabrication of diaphragm micromirror using a recently proposed novel process of ‘Bulk Lithography’. In contrast to classical microstereolithography (MSL) processes of 3D layer-by-layer micro fabrication, bulk lithography fabrication is done by scanning of laser beam over the photopolymer resin of unconstraint depth in a single layer scan. The process has capability to fabricate smoothly varying thickness diaphragms for micromirrors. However, as a first step, this paper demonstrates fabrication of uniform thickness micromirrors coated with aluminum. Micromirrors are fabricated with air trapped beneath them which contributes to enhanced stiffness and low damping. Further fabricated micromirror is characterized using laser doppler vibrometer.
Analysis of Plastic Deformation in Metal-Ceramic Nanolayers During Cyclic Indentation
Authors: Blada C. B. , Shen Y.-L.
Published: October 2013

The indentation behavior of metal/ceramic nanolayers is studied, with attention devoted to cyclic response under fixed maximum and minimum indentation loads. The primary objective is to examine the evolving plastic deformation in the ductile metal constrained by the hard ceramic layers. The model consists of alternating aluminum (Al) and silicon carbide (SiC) thin films on a silicon substrate, with the Al/SiC layered structure being indented by a diamond indenter. The rate-dependent viscoplastic response of Al is taken into account in the numerical model. It is shown that plastic deformation in the ductile Al layers continues to occur during the unloading phase of the first cycle, as well as during subsequent reload/unload processes. The cyclic plasticity results in an open load-displacement loop, and the indenter continues to move deeper with each cycle. For the control model of a homogeneous Al film, there is no hysteresis loop and the transient behavior soon approaches stabilization, showing repetitive elastic loading/unloading. The modeling results are also compared with cyclic nanoindentation experiments conducted on the same metal-ceramic multilayer system and control specimen.
A Numerical Modeling of Fast Pyrolysis of Spherical Biomass Particles
Authors: Kenarsari Saeed Danaei , Zheng Yuan
Published: October 2013

Fast pyrolysis is a thermal decomposition process of converting biomass to bio-oil, which takes place in the absence of the oxidizer. Computational fluid dynamics (CFD) models existing in the literature often neglect temperature gradients within the particles and this may have resulted in inaccuracy of the fast pyrolysis process model. In this paper a dynamic numerical model to simulate fast pyrolysis of spherical biomass particles that considers the temperature gradient inside the particle is developed. This model incorporates the conservation of energy equation, coupled with the chemical kinetics model and allows for the shrinkage of the biomass particle during fast pyrolysis. The impacts of external heat flux, particle size, and biomass feedstock on the pyrolysis characteristics have been explored in terms of products’ composition and conversion time. The predictions of the present model are compared and identified to be in good agreement with experimental data in the literature.
Dynamic Measurements of Micro-Meter Particle Detachment on Glass Surfaces
Authors: Kassab Asmaa Sadek , Ugaz Victor M. , King Maria D. , Hassan Yassin A.
Published: October 2013

This work presents a high resolution study of the condition under which a transient fluid flow causes spherical glass beads particles of 10–100 μm in size to detach from glass surfaces. The general approach is to conduct well-controlled experiments, to observe individual microparticle motion in short term resuspension, within a period up to 5s, and to focus on the basic detachment mechanisms of the resuspended particles to fully understand and quantify the behavior of particles immediately before liftoff. Particle tracking obtained from high-speed imaging of individual particle with 4000 frames/s, reveal three different types of motion: rolling/bouncing, immediate liftoff (where the particle showed immediate liftoff without any initial rolling/bouncing) and complex motion where particles travel with rolling/bouncing motion on the surface for a certain distance before liftoff. The longer it will take the particle to start its initial movement the more rapid is the liftoff once motion is initiated. The majority of particle trajectories from the glass substrate were parallel to the surface with complex motion, covering 25% of the total distance traveled in rolling/bouncing motion before liftoff. Additionally, Single layer detachment showed that the detachment percentage initially follow an exponentially increasing trend for a period of ∼ 1s, followed by a plateau phase for a period of 5s.
Active Vibration Control of a Double-Curved Shell Structure Using the Example of Stuttgart Smartshell
Authors: Weickgenannt Martin , Sawodny Oliver , Neuhaeuser Stefan , Sobek Werner
Published: October 2013

The present contribution deals with concepts for active vibration control of a thin double-curved shell structure. The structure, Stuttgart SmartShell, is located at the University of Stuttgart. It is made of softwood and is equipped with strain gages to determine the state of static and dynamic loading. Furthermore a force input is provided at the supports of the structure using hydraulic cylinders. Here a model-based two-degree-of-freedom control concept for vibration damping is presented which is based on a dynamical model derived from Finite Element simulations. The control strategy uses modal decoupling of the system states to enable the manipulation and damping of single eigenmodes. An optimal control strategy is chosen to dampen oscillations as quickly as possible while considering limitations on the force input and peak stresses. The proposed control algorithms are applied to the shell structure under consideration and their applicability is demonstrated by simulation and experimental results.