bluuebunny/crossref_metadata_2025 huggingface dataset:
Adhesion of C. Elegans to Agar Surfaces
Authors: Adams Kevin , Mailler Roger , Keller Michael W.
Published: October 2013

The surface adhesion between C. elegans and the agar plates on which they are commonly grown has yet to be accurately quantified. C. elegans are a scientifically important species of nematode whose simple structure allowed the first mapping of the complete nervous system in a multicellular organism. One of the current topics of research in the C. elegans community is the investigation of neuronal function in locomotion. Models of locomotion are used in these studies to aid in determination of the functions of specific neurons involved in locomotion. The adhesion force plays a critical role in developing these models. This paper presents the experimental determination of the adhesion energy of a representative sample of C. elegans. Adhesion energy was determined by a direct pull-off technique. In this approach, nematodes are anesthetized to prevent movement and secured to a small load cell before an agar plate is slowly brought into contact with the specimen and then removed. The maximum tensile force is then fit to a JKR-type adhesion model, which assumes that the nematode is a cylinder in order to determine the adhesion energy. Repeated adhesions are also investigated to determine the importance of drying on the measured adhesion force.
Using Hybrid and Problem-Based Learning Techniques to Enhance Teaching Effectiveness in a Large Feedback Controls Lecture Course
Authors: Parker Johné M. , Polston J. Daniel
Published: October 2013

Enrollments in Mechanical Engineering programs continue to increase. Unfortunately, increases in faculty size have not kept pace at many universities, resulting in large course enrollments in even junior- and senior-level major courses. The primary goals of this study were to increase (or at least maintain) the quality of instruction, and increase student competency and understanding in a large lecture course having the same instructional personnel resources as a course with 60% of the enrollment. Hybrid and problem-based learning techniques, along with two optional weekly recitation sessions and an online discussion forum were incorporated into the course to meet these goals.

The course, a classical controls course, is one in which course concepts are generally considered to be a bit abstract to a considerable percentage of the class. The instructor had previously taught the course several times, so a well-paced course schedule and solid foundation of course notes were already in place. Student evaluation instruments in previous offerings included weekly homework, bi-weekly short quizzes, two exams and the final exam.

For the large lecture course (with an enrollment of 84 students), the evaluation instruments (homework, quizzes and exams) remained the same; however, the students formed self-selected triad teams. Approximately two-thirds of the quizzes, one-half of the homework and sixty percent of the final exam questions were assigned to the triad teams (the balance and both mid-term exams were individual submissions). The primary advantages of group quizzes and assignments were multi-fold: they facilitated group learning and peer-teaching to reinforce course concepts and allowed the instructor and teaching assistant to give the type of detailed feedback on submissions that would have been difficult or impossible to give on 84 individual submissions.

Course notes (including short Echo360 modules), handouts and homework and quiz solutions were maintained on an online course management system (i.e., Blackboard); additionally, the use of an online threaded discussion forum, Piazza, allowed students to post/answer questions (anonymously, if desired) and follow discussions about course content.

Team-based learning techniques were heavily used in latter course topics; the assigned readings, along with online course notes were used to prepare the students for the individual readiness assessment tests (RATs). Students discussed their answers on the RAT instruments in their triad groups (another opportunity for peer teaching) and disclosed group answers (which generally reflected a much higher level of understanding) to the entire class.

Student assessment of course techniques and a comparison of traditional (lecture-based) and hybrid-/problem-based techniques will be used to assess the efficacy of the problem-based approach and to suggest improvements for future offerings.
Numerical Analysis of Condensation of R134a in a Single Microchannel
Authors: Ganapathy Harish , Shooshtari Amir , Choo Kyosung , Dessiatoun Serguei , Alshehhi Mohamed , Ohadi Michael M.
Published: October 2013

The present work proposes a numerical, transient modeling approach for the simulation of condensation heat transfer in a single microchannel. The model was based on the volume of fluid approach, which governed the hydrodynamics of the two-phase flow. User-defined routines were implemented in order to simulate the effects of condensation, which included mass transfer at the liquid-vapor interface and the associated release of latent heat. A channel having hydraulic diameter of 100 micrometer was modeled using a two-dimensional computational domain. The working fluid was R134a and the vapor mass fluxes at the channel inlet ranged from 245 to 615 kg/m2s. The channel wall was maintained at a constant heat flux, ranging between 200 to 800 kW/m2. The predictive accuracy of the numerical model was assessed by comparing the two-phase frictional pressure drop and Nusselt number with the available empirical correlations in the literature. A reasonably good agreement was obtained for both parameters with mean absolute errors as low as ±7.5% for pressure drop and ±15.6% for Nusselt number. Further, a qualitative comparison of various flow patterns against experimental visualization data was performed. The predicted flow patterns were classified based on the relative dominance of surface tension and inertia forces, and the results were in close agreement with visualization data. On the whole, the newly developed approach was found to have a high predictive accuracy with respect to the simulation of condensation phenomena in microscale domains and was concluded to be a useful tool in support of the design and optimization of advanced microchannel-based heat exchangers.
Contrast-Transfer Efficiency of Localized Harmonic Motion Imaging for Viscoelastic Soft Tissues: A Simulation Study
Authors: Zhao Xiaodong , Pelegri Assimina A.
Published: October 2013

Numerous biomechanical imaging techniques have been proposed for tissue examination and detection of pathologies.. In this study, a finite element model is developed to investigate contrast-transfer efficiency of harmonic motion imaging for viscoelastic soft tissues. Direct-solution steady-state dynamic analysis is used to compute the dynamic displacement amplitude in finite element simulations. Then, the contrast-transfer efficiency of harmonic motion imaging is investigated for different inclusion to background contrast ratios. The effect of excitation frequency and material viscosity on contrast-transfer efficiency is also studied. The results suggest that the contrast-transfer efficiency of harmonic motion imaging generally decreases as the viscosity of the tissue increases. Contrast-transfer efficiency of a higher excitation frequency declines faster as the viscosity of the tissue increases. Harmonic motion imaging is less efficient in depicting the stiffness contrast of soft inclusion in hard background than that of hard inclusion in soft background for high viscosity materials.
Nano-Structured Catalytic Material for Solar-Powered Biofuel Reforming
Authors: Hotz Nico
Published: October 2013

The main goal of this project is to combine two renewable energy conversion technologies (low-temperature fuel cells and solarthermal collectors) to achieve synergies in terms of cost and energetic efficiency compared to systems based on a single energy source and energy conversion technology. Direct solar-to-electric energy conversion, such as photovoltaics, is currently not economically competitive with traditional electric power generation. Fuel cell technology using alcoholic fuel possibly generated from biomass (e.g. methanol) is not competitive in terms of costs either. The system proposed for this project is based on relatively cheap, commercially available hardware components (intermediate-temperature solar collector, pressurized gas tank, hydrogen-fed Proton Exchange Membrane (PEM) fuel cell) and benefits in terms of energetic efficiency from the cost-free supply of solar heat. By applying micro-fabrication technology and nano-scale structures (e.g. for catalytic surfaces), the efficiency of all individual system components and of the entire system can be increased drastically.

The catalytic activity of micro-reactors containing this foam-like ceramic is tested in terms of their ability to convert alcoholic biofuel (e.g. methanol) to a hydrogen-rich gas mixture with low concentrations of carbon monoxide (up to 75% hydrogen content and less than 0.2% CO, for the case of methanol). This gas mixture is subsequently used in a low-temperature fuel cell, converting the hydrogen directly to electricity. A low concentration of CO is crucial to avoid poisoning of the fuel cell catalyst. Since conventional Polymer Electrolyte Membrane (PEM) fuel cells require CO concentrations far below 100 ppm and since most methods to reduce the mole fraction of CO (such as Preferential Oxidation or PROX) have CO conversions of up to 99%, the alcohol fuel reformer has to achieve initial CO mole fractions significantly below 1%. The catalyst and the porous ceramic reactor of the present study can successfully fulfill this requirement.
Prediction of the Temperature-Dependent Thermal Conductivity and Shear Viscosity for Rigid Water Models
Authors: Mao Yijin , Zhang Yuwen
Published: October 2013

The temperature-dependent thermal conductivity and shear viscosity of liquid water between 283K and 363K are evaluated for eight rigid models with the reverse non-equilibrium molecular dynamics (RNEMD). The five-site models (TIP5P and TIP5P-Ew) have apparent advantages in estimating thermal conductivities than other rigid water models that overestimate the value by tens of percent. For shear viscosity, no single model can reproduce all experimental data; instead, five- and four-site models show their own strength in certain temperature range. Meanwhile, all of current rigid models obtain lower values than experimental data when temperature is lower than 298K, while TIP5P and TIP5P-Ew model can relatively accurately predict the values than others at temperature range from 298K to 318K. At higher temperature range, shear viscosity of liquid water can be reproduced with four-site model (TIP4P-2005, TIP4P-Ew) fairly well.
Variation Analyses Using SugarCube
Authors: Jin Xing , Clark Jason V.
Published: October 2013

In this paper, we present new variation analysis features added to SugarCube. SugarCube is a novice-friendly online CAD tool for exploring the design space of compact MEMS models. Such variation analysis can help to evaluate the bounded effects of unavoidable process variations during the fabrication (such as Young’s modulus, overcut, gap asymmetry, etc.), packaging (such as variations in temperature, expansion coefficients, etc.), and operation (such as variations in voltage sources, etc.). Compared to other software tools for MEMS, the benefits of variation analysis in SugarCube include its comprehensiveness, ease of use, speed, and accessibility. In SugarCube, any geometric, material, or excitation parameter may be easily explored for its effect on device performance. Such analysis is expected to benefit feasibility analyses on process survivability, process yield, and operational robustness. For a couple of test cases, we perform our variation analysis on a micro-scale accelerometer and gyroscope.
Linear Modeling and Optimal Control of Bending in IPMC Actuators
Authors: Selekwa Majura , Tripathi Smriti
Published: October 2013

Ionic Polymer Metal Composites (IPMC) have been widely studied for the possibility of acting as artificial muscles in both macro and micro positioning tasks. This paper presents a linear electromechanical model for a bending IPMC actuator and a simple algorithm for positioning control by such an actuator. The electromechanical is based on principles of continuum mechanics, electrodynamics and statistics. The model was validated experimentally on a 200μm nafion IPMC specimen. Since the resulting model was found to be linear, a simple linear optimal control algorithm is proposed for controlling the positioning action of the actuator. Simulation and experimental results have agreed well, showing that the proposed model is able capture the dynamics of the actuator, and can be used to positioning tasks as may be needed.
Uncertainty Considerations in the Dynamics of Gear-Pair
Authors: Alemayehu Fisseha M. , Ekwaro-Osire Stephen
Published: October 2013

Gears and Gear systems are subjected to uncertainty of design parameters and loading caused by inherent conditions, measurement and manufacturing errors. Hence, the motivation of this work is to improve the deterministic design practice of gears and gear systems. A probabilistic rigid multibody dynamic gear-pair model with design and load uncertainties has been developed and analyzed. Rigid gear-pair model was developed in multibody dynamics software ADAMS and parameter uncertainty and probabilistic analysis was performed from separate probabilistic software called NESSUS. To perform the probabilistic multibody analysis, ADAMS and NESSUS were interfaced using MATLAB. The effect of parameter uncertainty on dynamic factor, DF of a gear pair was investigated. The sensitivity of DF to five uncertain loading and design parameters were also determined. This paper has demonstrated the importance of the novel PMBD modeling approach to gear design and dynamic factor analysis. The method has brought a new dimension of design approach of gears and gear systems than traditional approach that considers a certain empirically defined dynamic rating factors. In addition to revealing system reliability or under-performance through probability of failure, it also helps designers to consider certain variables critically through the sensitivity results.
Numerical Simulation of the Polymerization Process in Turbulent Reacting Flows
Authors: He Anpeng , Bonvillain Marie , Bennett Robert , Duhon Adam , Lin Victor , Zhang Ning
Published: October 2013

The present research entails turbulent reacting flow being simulated inside a low-density polyethylene tubular reactor using computational fluid dynamics techniques. The effects of initiator mass fraction and initiator injection speed on the stability of the reactor have been studied. The reactor and injector should be designed such that the ethylene does not undergo the potential decomposition reaction; this reaction is exothermic and violent. The products of the decomposition must be vented as a safety measure. ANSYS FLUENT has been used to simulate this reacting flow problem. Both decomposition reaction and polymerization reaction are entered into the software along with their kinetic information. A high product yield of polymer without initiating the ethylene decomposition reaction is expected. Optimal mass fraction of initiator and optimal injection velocity were determined in order to maximize product and maintain the stability of the low-density polyethylene tubular reactor.
Characterization of Physical Properties for Multi-Scale Polymer Composites Under Various Processing Conditions
Authors: Lederer Anne C. , Bigio David I. , Bruck Hugh A. , Sime Betel T. , Brown Harry R. , Fukuda Graeme M.
Published: October 2013

There is great interest in using microscale and nanoscale ingredients as fillers to create composites with enhanced physical properties. To further explore the improvement these fillers offer, a combination of both micro and nano ingredients was used to make a multi-scale polymer composite. Therefore we have engaged in an investigation to see how the physics of mixing these ingredients affects microstructural evolution of the extruded composites, as well as the associated thermal and mechanical properties. This data can then be used to develop fundamental processing-structure-property models of these multi-scale composites across different concentrations of microscale and nanoscale ingredients in order to optimize their development.
Comparative Analysis of Three Configurations Using Combinations Based on a Serpentine Geometry for the Species Distribution of a PEMFC
Authors: Contreras-Elizarraras V. , Hernandez-Guerrero A. , Elizalde-Blancas F. , Perez-Raya I. , Gamboa-Orozco G.
Published: October 2013

The present study shows the results obtained for a 3D CFD analysis for 3 configurations of the gas flow field of a PEM fuel cell: serpentine, interdigitated-serpentine and double serpentine. The objective of this study is to determine the current density distribution, the pressure drop, and the power generated by a PEM fuel cell operating under the proposed gas flow field. The model adopted for the analysis takes into account the effects of the electrochemical reactions that occur in the fuel cell, in this case the transport of electrons and protons, the species consumption, the water production in the catalyst and the water transport through the membrane. The results obtained for each configuration are compared to determine which configuration has the maximum performance.
Advances in Fan Modeling: Issues and Effects on Thermal Design of Electronics
Authors: Dogruoz M. Baris , Shankaran Gokul
Published: October 2013

Forced convection air-cooled electronic systems consist of fans to provide fluid flow through the enclosure. Typically axial flow fans, radial impellers, and centrifugal blowers fall into this category. In numerical computations of flow fields in electronic enclosures, axial fans have most commonly been abstracted as planar (2-D) rectangular or circular surfaces. In some cases, these abstract or lumped models may be used to mimic impellers and centrifugal blowers as well. All of these models rely on an experimentally derived “pressure head-flow rate” (P-Q) curve (also called “fan curve”). The experiments to obtain the fan curve should conform to the test codes published by ASME and/or AMCA.

Convenience and accuracy of abstract fan models are dependent on the specific application/cooling method and the acceptable error margin. The latter for the thermal design of electronics has recently diminished considerably which led to the need of using more accurate and robust fan modeling techniques such as Multiple Reference Frame (MRF) model. The authors validated this method for different types of fans against relevant experimental data previously [1,2]. As a continuation of this earlier effort, an attempt is made to examine the thermal field computed by various fan modeling techniques including MRF for air-cooled enclosures in the present work. The results show that the temperature values obtained from lumped fan model and the MRF technique differ considerably.
Vortex Tube Impact on Cooling Milling Machining
Authors: Alsayyed Basel , Hamdan Mohammad O. , Aldajah Saud
Published: October 2013

In this paper, the authors will present the use of a vortex tube in cooling milling operations. The focuses will be regarding the surface finish and temperature of the tool during the cutting operation. Three cooling setups, cutting without coolant, cooling with a water base traditional coolant, and cooling with vortex tube will be compared. A Flir E320 UV camera has been used to capture the heat map around the tool during the cutting process. The surface roughness has been measured and analysed for all three samples using Taylor/Hobson Precision Surtronc 3+ apparatus. The findings of this study have shown comparative efficient cooling using the vortex tubes. The vortex tube cooling is also cleaner and can be directed in such a way to collect the chips as they develop with the least mess or no mess. Vortex tubes have no moving parts, and it is very much maintenance free device. Compressed air is needed to feed the vortex tube, which is available usually in any machine shop.
Numerical Simulation of Polymers Powder Sintering Using Infrared Heating
Authors: Boutaous M’hamed , Msakni Amir , Barres Claire , Charmeau Jean-Yves
Published: October 2013

Three-dimensional parts are produced by selectively sintering or melting a thin layer of plastic powder, one layer on top of the other one, by exposure with IR-light through a digitally printed optical mask. The process thus transfers 2D images into 3D parts by melting each layer in a single exposure. This makes the SMS process significantly faster and more cost-effective than traditional laser sintering, which sinters each layer in a point-by-point fashion. The speed of the SMS process makes it suitable for use throughout the entire product life cycle for plastic parts; from the first prototypes, through production of parts, and finally to “Spare parts on demand.” It is easily revealed that replacing the laser by the infrared as a heat source increases greatly the productivity. However, there is still research work to be done in the purpose of optimizing the process and better understand the thermal and physicochemical changes undergone in the powdered polymeric material. In this paper, a coupling between a 1D thermal model and a crystallization model will be done to predict the thermal behavior of the polymer during the sintering by infrared flashing in rapid prototyping process. After that, the model will be tested and confronted to the experimentally results using a new lab-scale IR-sintering machine which was constructed in this purpose.
Silicon Thin-Film Lattice Dynamics and Thermal Transport Properties
Authors: Davis Bruce L. , Su Mehmet , El-Kady Ihab , Hussein Mahmoud I.
Published: October 2013

Thin films composed of dielectric materials are attracting growing interest in the solid state physics and nanoscale heat transfer communities. This is primarily due to their unique thermal and electronic properties and their extensive use as components in optoelectronic, and potentially in thermoelectric, devices. In this paper, an elaborate study is presented on silicon thin films ranging from a few nanometers in thickness to very thick bulk-like thicknesses. Full lattice dynamics calculations are performed incorporating the entire film cross section and the relaxation of the free surfaces. The phonon properties emerging from these calculations are then incorporated into Holland-Callaway models to predict the thermal conductivity and other phonon transport properties. A rigorous curve fitting process to a limited set of available experimental data is carried out to obtain the scattering lifetimes. Our results demonstrate the importance of proper consideration of the full thin-film dispersion description and provide insights into the relationship between thermal conductivity, film thickness and temperature.
Application of Conducting Polymer Composites With Cellulose Fibers on Water Softening
Authors: Barrera C. , Arrieta A. , Escobar N.
Published: October 2013

Hard water is unsuitable for industrial and domestic purposes given its high levels of calcium and magnesium divalents which generate scale, oxidation and are antagonistic of optimal performance of detergents and industrial equipment. Conventional methods for water softening generate by-products that need to be treated, which makes these methods economically and environmentally unsustainable and open the opportunity to develop new technology for this application.

The ion exchange behavior during the charge and discharge processes (i.e. oxidation / reduction), of conducting polymers and the combination of these materials with other such as fibers, to develop new hybrid materials that exhibit the inherent properties of both components, has been the object of many studies in the last years. The aim of this study is to evaluate the applicability of vegetable cellulose microfibers as a base to obtain a conducting polymer composite membrane with polypyrrole and to analyze the membrane performance to remove ions dissolved in hard water. The application of conducting polymer composite on water softening is based on the use of pyrrole’s electrochemical properties jointed to the flexibility and relatively high surface areas associated with cellulose, to promote an ion exchange reaction between the composite membrane and the hard water.

The cellulose membranes obtained from banana plant waste (raquis), were uniform with individual and well separated fibers. The fibers were successfully encapsulated by a continuous coating of polypyrrole through in situ oxidative chemical polymerization.

The amount of polypyrrole deposited on the fiber increased with increasing concentrations of the monomer, which was easily identified through the observation of differences on the intensity of the light to dark colour shift that coated the fibers after the polymerization.

The applicability of the conducting polymer composite on water softening was tested using an experimental device, finding reductions on the conductivity for hard water within 23 to 66 μs/cm after 6 hours of the assay.
The Federal Government’s Role in Enabling the Nuclear Renaissance and a Low-Carbon Energy Future
Authors: Hanson John
Published: October 2013

The electric power industry in the United States will face a number of great challenges in the next two decades, including increasing electricity demand and the aging of the current fleet of power plants. These challenges present a major test for the industry, which must invest between $1.5 trillion and $2 trillion by 2030 to meet the increased demand. In addition to these challenges, the potential for climate legislation, controversy over hydraulic fracturing, and post-Fukushima safety concerns have all resulted in significant uncertainty regarding the economics of all major sources of base-load electricity.

Currently nuclear power produces 22% of the nation’s electricity, and over 70% of the nation’s low-carbon electricity, even though unfavorable economic conditions have stalled construction of new reactors for over 30 years. The economics are changing, however, as evidenced by the recent construction and operating licenses (COLs) awarded by the Nuclear Regulatory Commission to Southern Company and SCANA Corporation to build two new units each. The successful construction of these units could lead to more favorable financing for future plants. This improved financing, especially if combined with appropriate additional government support, could provide serious momentum for the resurgence of nuclear power in the United States.

The most important way in which government support could benefit nuclear power is by increasing the amount of loan guarantees provided to the first wave of new nuclear power plants. This will help encourage additional new builds, which will help reduce the financing risk premium for new nuclear and improve interest rates for future plants. Instead of simply increasing loan guarantees for nuclear energy, a permanent federal financing structure should be established to provide loan guarantees for “clean energy” technologies in general, a category in which nuclear energy should be included. Most importantly, any changes should be made as part of a coherent, long-term energy policy, which would provide utilities with the correct tools to make the necessary investments, and the confidence that will allow them to undertake large-scale projects.
Numerical Investigation of Natural Convection Characteristics in a Water Tank
Authors: Talkhoncheh Fariborz Karimi , Wang Jinlong , Xu Hongtao , Yang Mo , Zhang Yuwen
Published: October 2013

In this paper, the numerical study is performed to investigate the natural convection characteristics in a 2D water tank model. The hot water flows in horizontal cylinder, heating the water stored in a water tank. The effects of different aspect ratios are numerically analyzed to inspect the natural convection characteristics in the 2D water tank model. The average and local Nusselt number over the cylinder surface at different aspect ratios and cylinder surface temperature are also discussed.
Low Energy Building Designs for Extreme Weather Conditions in Central Asia
Authors: Tokbolat Serik , Tokpatayeva Raikhan , Al-Zubaidy Sarim Naji
Published: October 2013

Buildings account for nearly 40% of the end-use energy consumption and carbon emissions globally. These buildings, once built, are bound to be utilized for several decades if not longer. The building sector therefore holds a significant responsibility for implementing strategies to increase energy efficiency and reduce carbon emissions and thus contribute to global efforts directed toward mitigating the adverse effects of climate change.

This paper presents an oversight of effective low-energy building design strategies for the extreme weather conditions in Kazakhstan (Astana), with temperature ranging between −35 and +40 C. Passive design features coupled with integration of renewable energy technologies have been identified for the next generation of buildings in Astana. The specific nature of the work is intentional, it is a continuing attempt to generate relevant know how that has direct relevancy to Astana’s system approach to energy conversation to meet its extreme winters.
A New Calibration Method and Device for Certified Flow Measurements With Laser Velocimetry
Authors: Shirai Katsuaki , Büttner Lars , Czarske Jürgen , Kykal Carsten
Published: October 2013

We aim to establish traceability at calibration and hence to enable a certified flow measurement with a calibrated measurement system. A new calibration method is presented for laser velocimetry. We develop a simple, unique method which establishes traceability of its uncertainty. The device is transportable and calibratable by any users for their own instruments on-site. Our new method requires only a rotating disk and a precision linear stage providing positional information. In former calibration methods, the uncertainty of the orbit radius of a scattering object was dominant due to the difficulty of accessing the true center of the rotation. The diffuculty was solved in our new method. The new method provides an accurate estimate of the orbit radius and hence the velocity of the calibration object through a linear regression. The calibration constant is obtained even without the need of direct access to the absolute value of the rotation radius. The uncertainty budget is examined throughout the calibration procedure. The traceability chain is established once the traceabilities are maintained to the translation stage and the motor used for rotating the calibration disk. The new method has been realized with three different calibration setups and their performances were investigated. We demonstrate that the new calibration method can achieve uncertainty down to 0.1%.
Solar Cooling With Ice Storage
Authors: Peyton-Levine Tobin , Sherbeck Jonathan , Magerman Beth , Phelan Patrick E.
Published: October 2013

Solar photovoltaics (PV) is hampered by the lack of solar radiation during peak energy demand hours of the day, e.g. 5–8pm. The ability to shift the PV power curve and make the energy accessible during peak hours can be accomplished through pairing solar PV with energy storage technologies. A system of combining solar PV and ice thermal storage in order to operate conventional heating, ventilation, air conditioning (HVAC) units has been developed. The hybrid air conditioning system (HACS) consists of an array of PV panels running a DC compressor which operates a conventional HVAC unit using R134a that has two evaporators. A simple test run consisting of cycling the glycol solution through the glycol air handler with all other components shut down was performed. The glycol air handler ran for 6 hours and the initial cooling power was 4.5 kWth.
Crossflow Over a Porous Circular Cylinder With Surface Blowing: CFD Analysis With Experimental Validation
Authors: Reif T. H. , Kulacki F. A.
Published: October 2013

Crossflow over a porous circular cylinder, with uniform blowing at the surface, was investigated experimentally and numerically. Two free stream conditions, Reynolds numbers 4,100 and 6,200, and five dimensionless blowing rate parameters (ratio of surface blowing to free stream velocity), 0.000 to 0.190, were studied experimentally. For simplicity, results for only one Reynolds number and three blowing cases are presented. A low speed wind tunnel was designed and constructed to give time-smoothed average velocities in the range of 61–122 cm/s. The tunnel was calibrated prior to the study. Velocity and pressure profiles were uniform up to 3.81 cm from the walls of the test section. Turbulence intensity, measured at the center of the test section, was 3.0% with an absolute error of 0.5%. Using hot wire anemometry, time-smoothed velocity profiles were measured at several radial and angular positions from the front to the rear stagnation point. The maximum absolute error in the velocity measurements was 12 cm/s and the positional error of the probe was 0.00254 cm. The numerical study employed the finite element method. The flow field was modeled as two-dimensional with half-symmetry. The unsteady, turbulent (k/ε) model had 2,160 elements and 2,287 nodes. Convergence and laminar flow was verified. When blowing was present, the numerical solution was found to give excellent agreement with the experiments in the entire flow field. For the no blowing test case, the agreement with the experiments was also excellent up to 20 deg from the rear stagnation point. Flow visualization, using smoke, was used to qualitatively study the large scale secondary flows in the wake region. These results helped explain the poorer agreement for the no blowing test case.
Sliding Mode Hybrid Impedance Control of Robot Manipulators Interacting With Unknown Environments Using VSMRC Method
Authors: Jafari Aghil , Monfaredi Reza , Rezaei Mehdi , Talebi Ali , Ghidary Saeed Shiry
Published: October 2013

In the present paper, the objective of hybrid impedance control is specified and a robust hybrid impedance control approach is proposed. Based on the concept of hybrid control, the task space is decomposed into position and force controlled subspaces. Impedance control is used in the position controlled subspace. Desired inertia and damping are applied in the force controlled subspace to meliorate the dynamic behavior of robot manipulator. Robust controller using the variable structure model reaching control (VSMRC) is introduced that can realize the objective impedance in the sliding mode in finite time. In order to overcome the chattering effect due to sliding mode approach, fuzzy logic methodology is employed in the control system. In addition, the reaching transient response is undertaken with prescribed quality. Simulating the control system for a 6DOF PUMA560 robot confirms the validity and effectiveness of the proposed control system.
Sputter-cleaned Epitaxial VxMo(1-x)Ny/MgO(001) Thin Films Analyzed by X-ray Photoelectron Spectroscopy: 1. Single-crystal V0.48Mo0.52N0.64
Authors: Greczynski Grzegorz , Kindlund Hanna , Petrov Ivan , Greene Joseph , Hultman Lars
Published: October 2013

Epitaxial VxMo(1-x)Ny thin films grown by ultrahigh vacuum reactive magnetron sputter deposition on Mg(001) substrates are analyzed by x-ray photoelectron spectroscopy (XPS). This contribution presents analytical results for 300-nm-thick single-crystal V0.48Mo0.52N0.64 films deposited by reactive cosputtering from V (99.95 % purity) and Mo (99.95 % purity) targets. Film growth is carried out at 900 °C in mixed Ar/N2 atmospheres at a total pressure of 5 mTorr, with a N2 partial pressure of 3.2 mTorr; a bias of −30 V is applied to the substrate. Films composition is determined by Rutherford backscattering spectrometry (RBS). XPS measurements employ monochromatic Al Kα radiation (hν = 1486.6 eV) to analyze V0.48Mo0.52N0.64(001) surfaces sputter-cleaned in-situ with 4 keV Ar+ ions incident at an angle of 70° with respect to the surface normal. XPS results show that the ion-etched sample surfaces have no measurable oxygen or carbon contamination; film composition, obtained using XPS sensitivity factors, is V0.33Mo0.67N0.64. All core level peaks, including the nearby Mo 3p3/2 (binding energy of 394.0 eV) and N 1s (at 397.6 eV) peaks, are well-resolved.
Extension of PENELOPE to protons: Simulation of nuclear reactions and benchmark with Geant4
Authors: Sterpin E. , Sorriaux J. , Vynckier S.
Published: October 2013

Purpose:

Describing the implementation of nuclear reactions in the extension of the Monte Carlo code (MC) PENELOPE to protons (PENH) and benchmarking with Geant4.

Methods:

PENH is based on mixed‐simulation mechanics for both elastic and inelastic electromagnetic collisions (EM). The adopted differential cross sections for EM elastic collisions are calculated using the eikonal approximation with the Dirac–Hartree–Fock–Slater atomic potential. Cross sections for EM inelastic collisions are computed within the relativistic Born approximation, using the Sternheimer–Liljequist model of the generalized oscillator strength. Nuclear elastic and inelastic collisions were simulated using explicitly the scattering analysis interactive dialin database for1H and ICRU 63 data for 12C, 14N, 16O, 31P, and 40Ca. Secondary protons, alphas, and deuterons were all simulated as protons, with the energy adapted to ensure consistent range. Prompt gamma emission can also be simulated upon user request. Simulations were performed in a water phantom with nuclear interactions switched off or on and integral depth–dose distributions were compared. Binary‐cascade and precompound models were used for Geant4. Initial energies of 100 and 250 MeV were considered. For cases with no nuclear interactions simulated, additional simulations in a water phantom with tight resolution (1 mm in all directions) were performed with FLUKA. Finally, integral depth–dose distributions for a 250 MeV energy were computed with Geant4 and PENH in a homogeneous phantom with, first, ICRU striated muscle and, second, ICRU compact bone.

Results:

For simulations with EM collisions only, integral depth–dose distributions were within 1%/1 mm for doses higher than 10% of the Bragg‐peak dose. For central‐axis depth–dose and lateral profiles in a phantom with tight resolution, there are significant deviations between Geant4 and PENH (up to 60%/1 cm for depth–dose distributions). The agreement is much better with FLUKA, with deviations within 3%/3 mm. When nuclear interactions were turned on, agreement (within 6% before the Bragg‐peak) between PENH and Geant4 was consistent with uncertainties on nuclear models and cross sections, whatever the material simulated (water, muscle, or bone).

Conclusions:

A detailed and flexible description of nuclear reactions has been implemented in the PENH extension of PENELOPE to protons, which utilizes a mixed‐simulation scheme for both elastic and inelastic EM collisions, analogous to the well‐established algorithm for electrons/positrons. PENH is compatible with all current main programs that use PENELOPE as the MC engine. The nuclear model of PENH is realistic enough to give dose distributions in fair agreement with those computed by Geant4.
Common Magnets, Unexpected Polarities
Authors: Olson Mark
Published: October 2013

In this paper, I discuss a “misconception” in magnetism so simple and pervasive as to be typically unnoticed. That magnets have poles might be considered one of the more straightforward notions in introductory physics. However, the magnets common to students' experiences are likely different from those presented in educational contexts. This leads students, in my experience, to frequently and erroneously attribute magnetic poles based on geometric associations rather than actual observed behavior. This polarity discrepancy can provide teachers the opportunity to engage students in authentic inquiry about objects in their daily experiences. I've found that investigation of the magnetic polarities of common magnets provides a productive context for students in which to develop valuable and authentic scientific inquiry practices.
Indirect Charged Particle Detection: Concepts and a Classroom Demonstration
Authors: Childs Nicholas B. , Horányi Mihály , Collette Andrew
Published: October 2013

We describe the principles of macroscopic charged particle detection in the laboratory and their connections to concepts taught in the physics classroom. Electrostatic dust accelerator systems, capable of launching charged dust grains at hypervelocities (1–100 km/s), are a critical tool for space exploration. Dust grains in space typically have large speeds relative to the probes or satellites that encounter them. Development and testing of instruments that look for dust in space therefore depends critically on the availability of fast, well-characterized dust grains in the laboratory. One challenge for the experimentalist is to precisely measure the speed and mass of laboratory dust particles without disturbing them. Detection systems currently in use exploit the well-known effect of image charge to register the passage of dust grains without changing their speed or mass. We describe the principles of image charge detection and provide a simple classroom demonstration of the technique using soup cans and pith balls.
An Alternative Introduction to Maxwell's Displacement Current
Authors: Reich Gary
Published: October 2013

In introductory texts Ampere's law is generally introduced in the steady-current form ∮B·dℓ=μ0I, and it is later extended to a more general form1–4 involving the socalled displacement current Id, ∮B·dℓ=μ0(I+Id).(1) Here the line integral is to be taken along a closed Amperian loop, and I is the net conventional current that penetrates any surface bounded by the loop. In its steady-current form (without Id), Ampere's law is used to find the magnetic field generated by highly symmetric arrangements of current-carrying wires, for example, an infinite straight line of current or an infinite solenoid, in analogy with Gauss's law.
Evaluating a Surprising Claim
Authors: Hayden Howard C.
Published: October 2013

A television advertisement and a website1 present an interesting question: can rail company CSX really move a ton of freight 468 miles on a gallon of fuel, or is the claim preposterous? Let us examine the claim, first by understanding what is meant, looking at their data, and then converting units to examine the claim quantitatively.
Pulse Oximetry in the Physics Lab: A Colorful Alternative to Traditional Optics Curricula
Authors: Kutschera Ellynne , Dunlap Justin C. , Byrd Misti , Norlin Casey , Widenhorn Ralf
Published: October 2013

We designed a physics laboratory exercise around pulse oximetry, a noninvasive medical technique used to assess a patient's blood oxygen saturation. An alternative to a traditional optics and light lab, this exercise teaches the principles of light absorption, spectroscopy, and the properties of light, while simultaneously studying a common medical device. Pulse oximeters are ubiquitous in clinical environments; many people who have undergone surgery or visited a hospital environment have experienced the use of this device, making it a good candidate for an investigative lab. The experiment elicits the creative process of device development from students as they conduct measurements using a blood analog that reconstructs the principles of pulse oximetry.
Efficacy of Tecovirimat (ST-246) in Nonhuman Primates Infected with Variola Virus (Smallpox)
Authors: Mucker Eric M. , Goff Arthur J. , Shamblin Joshua D. , Grosenbach Douglas W. , Damon Inger K. , Mehal Jason M. , Holman Robert C. , Carroll Darin , Gallardo Nadia , Olson Victoria A. , Clemmons Cody J. , Hudson Paul , Hruby Dennis E.
Published: October 2013

Naturally occurring smallpox has been eradicated but remains a considerable threat as a biowarfare/bioterrorist weapon (F. Fleck, Bull. World Health Organ.
81:
917–918, 2003). While effective, the smallpox vaccine is currently not recommended for routine use in the general public due to safety concerns (
http://www.bt.cdc.gov/agent/smallpox/vaccination
). Safe and effective countermeasures, particularly those effective after exposure to smallpox, are needed. Currently, SIGA Technologies is developing the small-molecule oral drug, tecovirimat (previously known as ST-246), as a postexposure therapeutic treatment of orthopoxvirus disease, including smallpox. Tecovirimat has been shown to be efficacious in preventing lethal orthopoxviral disease in numerous animal models (G. Yang, D. C. Pevear, M. H. Davies, M. S. Collett, T. Bailey, et al., J. Virol.
79:
13139–13149, 2005; D. C. Quenelle, R. M. Buller, S. Parker, K. A. Keith, D. E. Hruby, et al., Antimicrob. Agents Chemother.,
51:
689–695, 2007; E. Sbrana, R. Jordan, D. E. Hruby, R. I. Mateo, S. Y. Xiao, et al., Am. J. Trop. Med. Hyg.
76:
768–773, 2007). Furthermore, in clinical trials thus far, the drug appears to be safe, with a good pharmacokinetic profile. In this study, the efficacy of tecovirimat was evaluated in both a prelesional and postlesional setting in nonhuman primates challenged intravenously with 1 × 10
8
PFU of
Variola virus
(VARV; the causative agent of smallpox), a model for smallpox disease in humans. Following challenge, 50% of placebo-treated controls succumbed to infection, while all tecovirimat-treated animals survived regardless of whether treatment was started at 2 or 4 days postinfection. In addition, tecovirimat treatment resulted in dramatic reductions in dermal lesion counts, oropharyngeal virus shedding, and viral DNA circulating in the blood. Although clinical disease was evident in tecovirimat-treated animals, it was generally very mild and appeared to resolve earlier than in placebo-treated controls that survived infection. Tecovirimat appears to be an effective smallpox therapeutic in nonhuman primates, suggesting that it is reasonably likely to provide therapeutic benefit in smallpox-infected humans.
Ureteral injury after posterior lumbar discectomy with interbody screw fixation
Authors: Pillai Sunil Bhaskara , Hegde Padmaraj , Venkatesh Giridhar , Iyyan Bhalaguru
Published: October 2013

We report a case of iatrogenic ureteral injury secondary to L5 laminectomy and microdiscectomy with L5–S1 bone graft with posterior lumbar interbodyfusion using presacral cancellous screw fixation, managed by initial ureteral stent placement and subsequent Boari bladder flap repair. A 33-year-old woman underwent L5 laminectomy and microdiscectomy with L5–S1 bone graft with posterior lumbar interbody fusion using presacral cancellous screw fixation. On postoperative day 10, she developed lower abdominal pain, vomiting and fever. Ultrasonogram and contrast-enhanced CT demonstrated a large pelvic urinoma secondary to a right lower ureteric injury. This was managed initially by ureteral stent placement and subsequent Boari bladder flap repair. Ureteral injury following spinal surgery is a rare surgical complication with significant morbidity and mortality. A high index of suspicion is essential for early appropriate management and renal salvage.
The Role 1 capability review: mitigation and innovation for Op HERRICK 18 and into contingency
Authors: Wheatley Robert J
Published: October 2013

The Role 1 orientatedJRAMCof September 2012 was a welcome addition to the body of Role 1 literature. In particular, the Role 1 capability review by Hodgetts and Findlay detailed both current issues and future aspirations for Role 1 provision. This personal view considers issues still prevalent during Op HERRICK 18 namely the provision of primary healthcare by combat medical technicians on operations and the organisational issues that contribute to historical structural and attitudinal obstructions to the employment of combat medical technicians in firm base primary healthcare. It also considers a dynamically updating dashboard capable of displaying risk across the Role 1 network with the implied move to a model of continuous healthcare assurance.