bluuebunny/crossref_metadata_2025 huggingface dataset:
Limited View Tomography of Combustion Zones Using Tunable Diode Laser Absorption Spectroscopy: Simulation of an Algebraic Reconstruction Technique
Authors: Guha Avishek , Schoegl Ingmar
Published: October 2013

Temperature and concentration distributions of a simulated flame were reconstructed with the help of computer tomography and tunable diode laser absorption spectroscopy (TDLAS). Reconstructions were based on the simulated numerical values of temperature and concentration of a stationary flame. Integrated absorption measurements along the line-of-sight (LOS) across the flames due to absorption by water vapor (H2O) in the near infra-red (NIR) region, specifically the 6930–6940 cm−1 range, were simulated to obtain the projection values for tomography. Spectroscopic parameters for the absorptions transitions, such as line-strengths, transition wavenumbers, collisional broadening coefficients and coefficients for their temperature dependency were selected from the HITRAN 2004 database. Simulated LOS data are inverted using a multiplicative algebraic reconstruction technique (MART), which are known to outperform traditional filtered back projection methods for cases with limited numbers of views. Based on spatially resolved reconstructions of spectroscopic data, temperature and concentration distributions are calculated using the wavelength modulation spectroscopy with second harmonic detection (WMS-2f) technique. A parametric study based on the number of views, orientation of views and number of rays per view required by the ART is performed in order to assess requirements for an acceptable reconstruction.
Strain Hardening of Heat Treated Nanostructured WC-17Co Coatings and Their Sliding Wear Behavior
Authors: Saha Gobinda C. , ben Mahmud Tarek A. , Khan Tahir I.
Published: October 2013

Grain size, their distribution and geometry are important to study the dislocation behavior and grain boundary sliding of ceramic reinforced metallic composite materials. Grain size reduction has been shown to lead to significant improvements of the wear resistance in nanostructured materials. As the grain size decreases from polycrystalline to nanocrystalline range, abrasive wear resistance increases considerably from the increased hardness and volume loss following Archard’s law of wear. Further, the heat treatment effect on the content of the metallic binder in a ceramic-metallic (cermet) material is thought to increase the hardness with decreasing crystalline size, thereby improving the sliding wear behavior of materials. In this study, the high velocity oxy-fuel (HVOF) thermal spraying of nanostructured WC-17Co coatings with engineered ‘duplex outer coating’ is conducted. The microhardness and sliding wear studies of the coatings and their heat-treated counterparts are performed. The nanostructured coatings showed a significant increase in the microhardness and wear resistance when compared with those of the conventional microstructured coatings of the same composition. It is believed that the improved performance is related with the work hardening as well as dispersion hardening of the nanostructured grains in the deposited coatings.
Revitalizing the Engineering Curriculum Through Studio Based Instruction
Authors: Khan Fazeel , Birchfield Neal , Singh Kumar Vikram
Published: October 2013

Engineering curricula, regardless of the specific discipline, need to evolve. Realizing also that the pedagogical value of any educational artifact is closely linked to the methods of instruction used to interact with students, it is imperative that the development of new learning materials be accompanied by the implementation of innovative techniques with demonstrated success in knowledge transfer. This paper presents details of the development of studio styled modules associated with groups of courses within the mechanical and manufacturing engineering curriculum. Within each studio, newly developed activities engage students through experiential learning techniques. These activities, or learning exercises, represent a fusion of hands-on experimentation and computational simulation/analysis in key areas of engineering, such as dynamical systems, thermal sciences and materials. This endeavor is also intended to promote STEM education through enhancements in the quality of technical content, methods of instruction, training of student as effective educators, and the establishment of outreach activities expected to have an enduring effect on the preparation and recruitment of young talent into the sciences.
Frequency Dependent Dielectric Properties of BT/Parylene Nanocomposites for Energy Storage Applications
Authors: Hossain Muhammad E. , Liu Shuangyi , Li Jackie , O’Brien Stephen
Published: October 2013

With climbing worldwide oil prices and global warming, energy crisis poses a threat to living standards, economy, and even global environment. Nanodielectrics become one of the new materials activated to play a unique role in sustainable and clean energy production, energy transportation, energy storage, and end usage. Based on our recent research on frequency-dependent dielectric properties of BaTiO3 (BT) single domain, BT/parylene nanodielectric composites have been examined in wide-ranging frequency at room temperature by several theoretical models. The projected models combined with Debye type of dissipation and soft mode theory to obtain more precise frequency dependent dielectric spectrum. Among the others, Wiener mixture rule, Lichtnecker model, Rayleigh model, Yamada rule, Maxwell-Wagner model, modified Kerner model were used to find frequency dependent nanocomposites dielectric spectrum. The predicted results are compared with our experimental results and explored the frequency dependent dielectric behavior of nanodielectric composites. The dielectric constant decreases while dielectric loss increases with increasing frequency due to at very high frequency, only electronic polarization can occur. This investigation provides the fundamental knowledge on dielectric properties of nanocomposites with a wide frequency range instead of trial-and-error strategy of experiments for the future development of energy storage devices.
Effectiveness of Introducing Problem Based Learning in the Undergraduate Engineering Curriculum
Authors: Khanna Sanjeev K. , Winholtz Robert A. , Jonassen David H. , Tawfik Andrew , Henry Holly
Published: October 2013

Problem solving is the primary intellectual activity of engineers. Therefore, enhancing problem-solving skills is essential for preparing engineering students for practice in the profession. A powerful approach for enhancing problem-solving skills is the problem-based learning (PBL) method. This paper presents the design and construction of a PBL-based course in materials science at the junior level in a mechanical & aerospace engineering (MAE) department. We assess the ability of a PBL course based on longer complex problems to enable students to learn both fundamental knowledge of the subject matter and also problem solving skills and contrast it with outcomes in a traditional lecture based course. The issues and challenges faced in assessing and implementing PBL are discussed.
The Effect of Thermal Resistance for Dropwise Condensation on Hydrophobic Micro-Pillared Structures
Authors: Beaini Sara S. , Mendoza Hector , Carey Van P.
Published: October 2013

Superhydrophobic/hydrophobic surfaces, developed to promote dropwise condensation, can be produced by modifying the surface chemically with low surface energy films, and/or structurally by fabricating micro-textured surfaces. Some research has reported the increased thermal resistance from the added chemical layer and its effect on condensation heat transfer. A critical question of interest is the thermal resistance due to micro-pillared structures and their influence on droplet growth during condensation as compared to smooth or non-textured surfaces. Though idealized, this paper presents a theoretical and computational model for evaluating and quantifying the effects of the pillared structures thermal resistance, as well as the continuum versus non-continuum mechanisms affecting droplet growth during dropwise condensation. The model is used to compare different micro-pillared surfaces, cited in the literature, and to predict which micro-pillar dimensions contribute to slower condensate growth despite the higher contact angle advantage during dropwise condensation.
Dynamics and Motion Control of a 6-DOF Robot Manipulator
Authors: Mondragon Carlos , Fotouhi Reza
Published: October 2013

This research work is to control motion of a manipulator attached to a mobile robot for pick-and-place operations; this is part of a bigger project in developing a robotic-assisted nursing to be used in medical settings. In this paper a strategy to accomplish pick-and-place operations, using a six degree-of-freedom robotic arm, is presented. Such operations are completed by creating a collision-free path to move an object from an initial to a final position. The collision-free path is planned by considering the entire workspace of the manipulator. The workspace is defined as the subtraction of the stationary objects and the robot volumes from all of the possible reachable points of the robotic arm. Once the path is planned, the kinematics of the manipulator is considered. Although this project can be applied into a wide range of applications, it is mainly intended to be used for medical robotic assistance. Simulation results for several different paths are presented. The simulation results were verified with experimental results, although not shown here.
Waste-Heat for Pre-Heating Internal Combustion Engines
Authors: Unnthorsson Runar , Palsson Halldor , Magnusdottir Rikey Huld
Published: October 2013

The pre-heating of engine coolant using electrical and fuel-based pre-heaters has been practiced for decades. There are many valid reasons for pre-heating engines such as increasing fuel economy, reducing pollution from combustion, reducing engine wear and increasing comfort. Those reasons are particularly true in colder climates where cars are used for short trips of up to 10 minutes or 5 kilometers.

In this paper an unconventional approach for pre-heating engines before starting is studied. The pre-heating is accomplished by assuming storage of a certain amount of the engine’s hot coolant in an insulated storage system when not operating the vehicle, and pumping it back into the engine’s coolant system before restarting. The approach does not rely on external power sources, except for control and pumping of the coolant.

The paper presents results from experimental tests made to evaluate the approach. The experimental tests were run with different settings. In one setting the system produced an average of 26 kW for fifty seconds (peaking at 41 kW). This power is considerably higher than the 2–6 kW provided by common commercial electrical and fuel-powered pre-heaters. Although 50 second pre-heating using the approach presented here will not match all commercial systems using 8–10 minutes heating time, the approach has room for improvement.
Wireless ISFET pH Sensor Network for Offshore Microalgae Cultivation
Authors: Malinowski John , Wiley Patrick , Trent Jonathan , Geiger Emil J.
Published: October 2013

Microalgae technology continues to show tremendous promise for becoming a major source of renewable transportation fuel in the coming decades. However, for microalgae to provide a significant fraction of the current US demand for fuel, their cultivation will be required on an enormous scale. One of the many formidable challenges that must be met to achieve this scale is the development of appropriate sensor networks to provide information about the growth conditions and the algae themselves. These sensors would monitor the heterogeneity of a) environmental parameters, such as pH, oxygen, and nutrient levels and b) algal characteristics such as size, oil content, and viability. Here we present a wireless sensor network to measure the local pH in NASA OMEGA project (Offshore Membrane Enclosures for Growing Algae). The pH is measured using Ion Sensitive Field Effect Transistor (ISFET) technology, which is more robust and has a faster response than traditional glass pH electrodes. A custom circuit drives the ISFET sensor and interfaces with an ANT wireless network system. The wireless network consists of a network hub which can service up to 8 sensor nodes and a series of relays to transmit the data to a PC. The data is logged with a custom LabVIEW program. In this work, we demonstrate operation of this network using a single ISFET pH sensor, one hub, and two relay units. The performance of the pH sensor network is evaluated and compared in parallel with an existing wired glass electrode based pH monitoring system at the NASA OMEGA project.
Fin Drive Propulsion
Authors: Asgeirsson Saethor , Unnthorsson Runar
Published: October 2013

This paper presents the results of a study, which aimed to understand and evaluate the locomotion of Atlantic salmon and Arctic char under three different swimming conditions, slow, medium and fast swimming. A Fourier-series based numerical model that describes the swimming mode for each condition is represented.

The numerical model is based on a video analysis of swimming fish. A video recording system was used to record the movement of two fish species under different swimming conditions in a swimming tunnel. The movements of eleven points on the fishes were tracked from the video recordings and logged. The movements of each point were then analyzed in Matlab and a 2nd degree Fourier model constructed to describe the motion.
SuperCritical Auto-Thermal Rankine (SCATR) System: High Efficiency Fossil Fuel Based Electricity With Intrinsic Carbon Separation
Authors: Calbry-Muzyka Adelaide S. , Mobley Paul D. , Edwards Chris F.
Published: October 2013

This paper presents SCATR: a novel, high-efficiency electricity generation system with carbon separation. The system uses oxygen from an air separation unit to burn methane in supercritical water, expanding the resulting products stream through turbines to generate power. The water is condensed, preheated, and recycled through the plant, leaving a stream of CO2 compressed to pipeline pressures. The details of the model are discussed, and an exergy analysis of the system is performed, providing insight into the operation of the plant as well as possible avenues for improvements. The efficiency of the system, including air separation and CO2 separation, is found to be 42.3% relative to the HHV of methane (or 47.0% relative to its LHV).
Sensitivity of Thermal Conductivity of Carbon Nanotubes to Defect Concentrations and Heat-Treatment
Authors: Bifano Michael F. P. , Park Jungkyu , Prakash Vikas
Published: October 2013

In the present study, classical MD simulations using reverse non-equilibrium molecular dynamics with the AIREBO interatomic potential are used to investigate the sensitivity of thermal conductivity in SWCNTs to side-wall defect concentration and heat-treatment. Two types of defects are investigated. First, the thermal conductivity of (6,6) SWCNTs is obtained as a function of concentration of chemisorbed hydrogen adatoms. Secondly, the thermal conductivity is obtained as a function of point-vacancy concentrations. The results of the studies show that 2 atom% of hydrogenation and 1.5–2% vacancy concentrations have very similar detrimental effects on the thermal conductivity of SWCNT. Vacancy repair is evident with heat treatment, and heat-treatments at 3000°C for up to 22 ns are found to transform point vacancies into various types of non-hexagonal side-wall defects; this vacancy repair is accompanied by a ca. 10% increase in thermal conductivity. Thermal conductivity measurements in both heat-treated and non-heat treated chemical vapor deposition grown MWCNTs are also reviewed. The results suggest that CNT thermal conductivity can be drastically increased if measures are taken to remove common defects from the SWCNT side-walls.
Effect of Porous Media Properties on Heat Transfer in Triangular Porous Duct
Authors: Mortazavi S. Negin , Hassanipour Fatemeh
Published: October 2013

This study presents an analysis of forced convection in a porous triangular channel. The flow is laminar, fully developed and assumed to have constant properties. The porous channel has an isotropic matrix and the boundary conditions are fixed with constant temperature. In this paper, accurate analytical solutions are presented to determine the effects of apex angle and porous media properties on the velocity and temperature distribution in a triangular channel along with the friction factor fRe, and Nusselt number NuT. The presentaion includes numerical features of the exact series solution using Brinkman’s model. Numerical results for dimensionless average temperature and velocity are presented for various porosities, permeabilities and apex angles.
Mass and Heat Transfer Characteristics of a Single-High Aspect Ratio Microchannel Absorber
Authors: Liu Yunshan , Al Hajri Ebrahim
Published: October 2013

Recently, study on a microscale-based absorption refrigeration system has sprung up motivated by the need of efficient energy utilization. Heat-driven absorption systems offer a possibility of generating both power and cooling with environment friendly refrigerants, such as ammonia/water and LiBr/water. However, these systems are often large in size and low in COP especially in single stage absorption systems. These characteristics of absorptions systems make them unattractive in most cases. This work introduces the utilization of micro-channel enhanced surfaces as heat exchangers to enhance the component and system performance, to reduce the system size and to reduce the cost of the system as well. In this work, a new concept of enhancing heat and mass transfer processes is applied in the absorber part of the absorption cycle by using a single micro-channel. Due to its merit of high area to volume ratio, microchannel technology has been well theoretically validated to be a very effective and potential choice for enhancing heat transfer performance. But there is a lack of research work on the mass transfer performance in micro-channels. This work investigated simultaneous mass and heat transfer characteristics of a novel microchannel absorber that uses LiBr/water as the working fluid. A microchannel with hydraulic diameter of 0.7mm is employed in this characterization study. Velocity distribution, pressure drop, concentration and temperature profile inside the microchannel as well as effects of the inlet absorbent concentration, flow rate and temperature together with the refrigerant flow rate on the heat/mass transfer are predicted. Investigations on the optimum inlet angle design of a single channel absorber are also presented in the end of this work. Feasibility of this novel absorber design was proved via this numerical simulation as the mass transfer taking place inside the mixing channel was observed to achieve the identical performance but with a size reduction by 1/27 compared to a conventional falling film absorber. A 7 times enhancement of the heat transfer coefficient was also achieved with the comparison of a macro-scale based absorber configuration.
On Interfacial Fracture Toughness Measurements of a Single Glass Fiber
Authors: Tenorio Max , Pelegri Assimina A.
Published: October 2013

The interfacial relationship between a glass fiber bundle and epoxy resin is investigated. A cylindrical notched specimen with a single bundle of fibers along the axis is created to observe debonding behavior. It is subsequently subjected to a quasi-static tensile test. The purpose of the test is to examine the interfacial debonding between fiber and resin from the point of breakage. All specimens reached a critical stress value and exhibited debonding to some degree. Experimental composite material properties are calculated and compared to technical data.
A Parameter Study on Effect of Pattern of Motion on Walking Speed of Biped
Authors: Farizeh Tara , Mansouri Saeed , Sadigh Mohammad Jafar
Published: October 2013

Study of fast motion of bipeds is an interesting subject for researchers. It is well known that for a specified biped, with certain physical parameters and actuation capability, change of kinematic parameters of motion may change the speed of motion. Among such parameters are mean value of hip height, relative horizontal position of hip at the beginning and end of single support phase and top position of ankle and its relative horizontal position. This work presents a parameter study in which a phase-plane analysis for minimum time motion of a biped is used to find maximum speed of biped for different values of each parameter in one step. The frame work of minimum time solution is such that it fulfills zero moment point criterion for stability and friction condition for slippage prevention.
A Critical Assessment of How Leaning the Risk Assessment Process Induces Biased Judgement
Authors: Al-Hajri Jefain , Kidd Moray
Published: October 2013

Over the years, the hydrocarbon industry has been riddled with accidents and incidences that can be partly blamed on “cost cutting” driven risk assessments and operational “lean management”. The epicentre of lean management is the elimination of waste for any industrial setup. However, when the processes are too lean accidents may ensue; putting the facilities, workers and the business at risk. Even though the hydrocarbon industry has reliable quantitative risk assessment techniques that may incorporate probabilistic measures to predict the likelihood of systems failure, there are times when “human call” is cardinal to decisions. Whenever human call is used in risk assessment there is a possibility of biasness in the judgement for risk partly due to the social-cultural influence on risk assessors. Therefore the aim of this research was to examine the level of social and cognitive bias in risk assessment of lean management processes at four oil and gas refinery plants in Kuwait. Using ethnomethodology as a research strategy it was possible to gather contextual primary information from the workers at the four refineries. Results from the research indicate that there is a high level of human involvement in risk assessment processes where social-cultural and psychological attributes of the risk assessors are evident. However, current risk assessment tools and processes do not engage risk assessors at a social-cultural level; hence ignoring the influence of biased judgement on risk scores. It can therefore be concluded that unlike technical risk assessment, there is poor incorporation of social-cultural and psychological initiatives in the processes leading to poor decisions that endanger hydrocarbon installations. It is recommended that the hydrocarbon industry in Kuwait strives to apply lean management principles by ensuring that there is detailed analysis of social and cognitive bias in the technical proceedings so as to simultaneously promote efficiency and safety at work.
Focusing Properties of Axisymmetric Acoustic Metamaterials Made of Toroidal Scatterers
Authors: Romero-García V. , Picó R. , Cebrecos A. , Garcia-Raffi L. M. , Sánchez-Pérez J. V. , Sánchez-Morcillo V. J.
Published: October 2013

We present the theoretical analysis of a periodic structure based on a transformational design of an axisymmetric system from a two-dimensional (2D) Sonic Crystal (SC). Applying an axial rotation of a 2D SC, we obtain a three dimensional (3D) axisymmetric structure made up of toroidal scatterers. Based on the propagating properties of the 2D system, we interpret the scattering produced by the 3D axisymmetric structure, and one can also use the homogenization approach in the long wavelength regime to design a refractive media with controlled effective parameters. We use both the multiple scattering theory, for the analysis of the 2D systems, and the finite elements methods, for the case of 3D axisymmetric structures. This system, due to the axial symmetry, could be useful to manage the radiation properties of sources presenting that symmetry. Moreover it may be useful by transforming in scale to different sizes, and as a consequence, to be applied at different ranges of frequencies.
Removing the Hot-Spots in High Power Devices Using the Thermoelectric Cooler and Micro Heat Pipe
Authors: Hirachan Agat , Agonafer Dereje
Published: October 2013

Due to localized high heat fluxes, hot-spots are created in silicon chips. Cooling of the hot-spots is one of the major thermal challenges in today’s integrated circuit (IC) industry. Many researches have been conducted to find ways to cool hot-spots using different techniques as uniform heating is highly desired. This paper focuses on cooling of hot-spot using conventional thermoelectric cooler (Melcor_CP1.0-31-05L.1) and a micro heat pipe. A chip package with conventional integrated heat spreader and heat sink was designed. Hot-spot was created at the center of the silicon die with background heat at rest of the area. The heat flux on the hot-spot was much greater than rest of the area. Forced convection was used to cool IC package, temperature was observed at active side of the silicon die. After that a copper conductor was used to take away heat directly from the hot-spot of the silicon die to the other end of the conductor which was cooled using the thermoelectric cooler. Finally the conductor was replaced by a heat pipe and a comparison between three cases was done to study the cooling performance using the commercial software, ANSYS Icepak. The effect of trench on silicon die was also studied.

In this paper the United States Patent, Patent No. US 6,581,388 B2, Jun. 24 2000 [8] as shown in Fig. 1 (b) was modified by replacing the conductor with a micro heat pipe to solve the hot-spots problem in electronic packaging.
Rayleigh Taylor Experiments
Authors: Kuchibhatla Sarat , Ranjan Devesh
Published: October 2013

Effect of multi-modal initial conditions on Rayleigh-Taylor instability (RTI) was experimentally studied at Texas A&M University. Precisely controllable initial conditions were generated using a flapper mechanism at the interface of two unstably stratified convective water streams with a temperature difference of about 7–8°C corresponding to Atwood numbers of the order of 10−3. By selecting input initial wavelengths and phase angles, a parametric study was performed to study the initial growth stages of this instability and mixing behavior. Using a servo controlled flapper mechanism and high resolution thermocouples, the quality and quantity of total and molecular mixing is studied. The topology of the characteristic bubble and spike structures in the initial mixing stages was recorded using high-resolution imaging. Density measurements using thermocouple measurements were performed at two downstream locations from the splitter plate, x/H = 0.077 and x/H = 0.908, where H is the total height of the Water Channel. Molecular mixing patterns due to single, binary and multi-mode initial conditions are extracted from density data.
Multi-Layer, Pseudo 3D Thermal Topology Optimization of Heat Sinks
Authors: McConnell Caroline , Pingen Georg
Published: October 2013

In order to overcome the high computational costs of 3D fluid-thermal topology optimization we introduce a pseudo 3D model consisting of a conductive base-layer and a coupled fluid-thermal design layer. While developed with heat sink designs in mind, the resulting topology optimization approach can be applied to other fluid-thermal design problems where 2D flow effects dominate. We introduce the coupled fluid-thermal solver based on the lattice Boltzmann method, develop and validate the sensitivity analysis for the model, and illustrate the resulting optimization framework for a heat sink design problem.
Simulations of the Tilted Rig Experiment Using the xRAGE and FLAG Hydrocodes
Authors: Rollin Bertrand , Denissen Nicholas A. , Reisner Jon M. , Andrews Malcolm J.
Published: October 2013

The tilted rig experiment is a derivative of the rocket rig experiment designed to study mixing of fluids by the Rayleigh–Taylor instability. In this experiment, a tank containing two fluids of different densities is accelerated downwards between two parallel guide rods by a rocket motor. The rocket rig is inclined by a few degrees off the vertical to force a two-dimensional Rayleigh–Taylor instability. Thus, the tilted rig experiment can help calibrate two-dimensional mixing models. Simulations of the tilted rig experiments using two of Los Alamos National Laboratory’s hydrocodes are reported. Both codes, xRAGE and FLAG, are multidimensional, multimaterial, massively parallel, hydrodynamics codes that solve the Euler equations. xRAGE operates in an Eulerian framework, while FLAG operates in an Arbitrary Lagrangian–Eulerian (ALE) framework, with a Lagrange step followed by mesh relaxation and remapping. Direct comparisons between simulations and experimental results are reported, as well as report the behavior of the variable-density turbulence models implemented in the codes.
Demand Response and FERC Mandated Compensation Issues
Authors: Lincoln Donald
Published: October 2013

This paper describes a Demand Response (DR) pilot event performed at Sandia National Laboratories in August of 2011. This paper includes a description of the planning for the demand response event, sources of energy reduction during the event, the potential financial benefit to Sandia National Laboratories from the event, event implementation issues, and the event results. In addition, this paper presents the implications of the Federal Energy Regulatory Commission (FERC) Order 745, Demand Response Compensation in Organized Wholesale Energy Markets, issued in March 2011. In this order FERC mandates that demand response suppliers must be compensated by the organized wholesale energy markets at the local market price for electricity during the hour the demand response is performed.

Energy management in a commercial facility can be segregated into energy efficiency and demand response. Energy efficiency focuses on steady state load minimization. Demand response reduces load for event-driven periods during the peak load. Commercial facility demand response refers to voluntary actions by customers that change their consumption of electric power in response to price signals, incentives, or directions from grid operators at times of high wholesale market prices or when electric system reliability is jeopardized. Demand-response-driven changes in electricity use are designed to be short-term and centered on critical hours during the day when demand is high or when the electricity supplier’s reserve margins are low. Demand response events are typically scheduled between 12:00 p.m. and 7:00 p.m. on eight to 15 days during the hottest period of the year. Analysis has determined that automated demand response programs are more efficient and effective than manually controlled demand response programs due to persistence.

FERC has stated that their Order 745 ensures organized wholesale energy market competition and removes barriers to the participation of demand response resources. In Order 745, FERC also directed that the demand response compensation costs be allocated among those customers who benefit from the lower prices for energy resulting from the demand response. FERC has allowed the organized wholesale energy markets to establish details for implementation methods for demand response compensation over the next four years following the final Order issue date. This compensation to suppliers of demand response can be significant since demand response is typically performed during those hours when the wholesale market prices are at their highest levels during the year.
Examining the LEED Rating System Using Approximate Inverse Optimization
Authors: Turner Sarina D. O. , Chan Timothy C. Y.
Published: October 2013

The Leadership in Energy and Environmental Design (LEED) rating system is the most recognized green building certification program in North America. In order to be LEED certified, a building must earn a certain number of points, which are obtained through achieving certain credits or design elements. Prior to LEED version 3, each credit was worth one point. In this study, we develop an inverse optimization approach to examine how building designers intrinsically valued design elements in LEED version 2. Due to the large dimensionality of the inverse optimization problem, we develop an approximation to improve tractability. We apply our method to 18 different LEED-certified buildings in the United States. We find that building designers did not value all credits equally and that other factors such as cost and certification level play a role in how the credits are valued. Overall, inverse optimization may provide a new method to assess historical data and support the design of future versions of LEED.
Performance of Thermoactive Foundations for Commercial Buildings
Authors: Kwag Byung Chang , Krarti Moncef
Published: October 2013

A transient three-dimensional numerical model is developed to model the performance of thermoactive foundations used to heat and cool commercial buildings. Using laboratory testing data, the numerical model is validated and used to carry out a sensitivity analysis to assess the most important design and operating parameters that affect the performance of thermoactive foundations. It is found that the foundation depth, the shank space, the fluid flow rate, and the number of U-tube loops in each foundation pile are the main parameters that affect the thermal performance of a thermoactive foundation system. Based on the validated numerical model, thermal response factors for a thermoactive foundation are developed, and implemented into a detailed building energy simulation program. These thermal-response factors are then used to estimate the impact of installing thermoactive foundations on the total energy use of typical office buildings in various US climates.
Efficient Numerical Investigation of Ventilation System Design of Road Tunnels
Authors: Wu Dicken K. H. , Lin Y. F. , Pin Y. F. , Tsui Dora W. S.
Published: October 2013

The road tunnel air quality would easily deteriorate if the vehicle-emitted exhaust gas is not properly removed or diluted. As a result, one of the major functions of effective ventilation in road tunnels is to prevent harmful substances from affecting tunnel users and also to maintain good visibility inside for safety consideration. In the present study, a highly efficient three-dimensional computational fluid dynamics (3D CFD) simulation method has been developed and tested to model the traffic induced piston effect in a full scale road tunnel. This method is useful for the design of tunnel ventilation systems.
Influence of Pipeline Inclination on Hydraulic Conveying of Sand Particles
Authors: Nossair Ahmed Mohamed , Rodgers Peter , Goharzadeh Afshin
Published: October 2013

The understanding of sand particle transport by fluids in pipelines is of importance for the drilling of horizontal and inclined hydrocarbon production wells, topside process facilities, infield pipelines, and trunk lines. Previous studies on hydraulic conveying of sand particles in pipelines have made significant contributions to the understanding of multiphase flow patterns, pressure drop and particle transport rate in horizontal pipelines. However, due to the complexity of the flow structure resulting from liquid-sand interactions, the mechanisms responsible for bed-load transport flow for hydraulic conveying of sand particles have not been extensively studied in inclined pipelines. This paper presents an experimental investigation of hydraulic conveying of sand particles resulting from a stationary flat bed in both horizontal and +3.6 degree upward inclined pipelines. The characteristics of sand transportation by saltation from an initial sand bed are experimentally visualized using a transparent Plexiglas pipeline and high-speed digital photography. The dune formation process is assessed as a function of pipeline orientation. Based on the visualized dune morphology, pipeline inclination is found to have a significant influence on hydraulic conveying of sand dune dynamics (i.e., dune velocity), as well as sand dune geometry (i.e., dune pitch and characteristic dune angles).
Sputter-cleaned Epitaxial VxMo(1-x)Ny/MgO(001) Thin Films Analyzed by X-ray Photoelectron Spectroscopy: 2. Single-crystal V0.47Mo0.53N0.92
Authors: Greczynski Grzegorz , Kindlund Hanna , Petrov Ivan , Greene Joe , Hultman Lars
Published: October 2013

Epitaxial VxMo(1-x)Ny thin films grown by ultrahigh vacuum reactive magnetron sputter deposition on MgO(001) substrates are analyzed by x-ray photoelectron spectroscopy (XPS). This contribution presents analytical results for 300-nm-thick single-crystal V0.47Mo0.53N0.92/MgO(001) films deposited by reactive cosputtering from V (99.95% purity) and Mo (99.95% purity) targets. Film growth is carried out in a UHV chamber with base pressure 2 × 10−9 Torr at 700 °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 V0.47Mo0.53N0.92(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 V0.34Mo0.66N0.81. All core level peaks, including the nearby Mo 3p3/2 (binding energy of 394.1 eV) and N 1s (at 397.5 eV) peaks, are well-resolved. Comparison to the V0.48Mo0.52N0.64 single-crystal film, submitted separately to Surface Science Spectra, indicates that with decreasing growth temperature from 900 to 700 °C (and increasing nitrogen concentration in VxMo(1-x)Ny from y = 0.64 to 0.81) the N 1s core level peak shifts towards lower binding energy by 0.1 eV while all metal atom peaks move in the opposite direction by the same amount.
Source position verification and dosimetry in HDR brachytherapy using an EPID
Authors: Smith R. L. , Taylor M. L. , McDermott L. N. , Haworth A. , Millar J. L. , Franich R. D.
Published: October 2013

Purpose:

Accurate treatment delivery in high dose rate (HDR) brachytherapy requires correct source dwell positions and dwell times to be administered relative to each other and to the surrounding anatomy. Treatment delivery inaccuracies predominantly occur for two reasons: (i) anatomical movement or (ii) as a result of human errors that are usually related to incorrect implementation of the planned treatment. Electronic portal imaging devices (EPIDs) were originally developed for patient position verification in external beam radiotherapy and their application has been extended to provide dosimetric information. The authors have characterized the response of an EPID for use with an192Ir brachytherapy source to demonstrate its use as a verification device, providing both source position and dosimetric information.

Methods:

Characterization of the EPID response using an192Ir brachytherapy source included investigations of reproducibility, linearity with dose rate, photon energy dependence, and charge build‐up effects associated with exposure time and image acquisition time. Source position resolution in three dimensions was determined. To illustrate treatment verification, a simple treatment plan was delivered to a phantom and the measured EPID dose distribution compared with the planned dose.

Results:

The mean absolute source position error in the plane parallel to the EPID, for dwells measured at 50, 100, and 150 mm source to detector distances (SDD), was determined to be 0.26 mm. The resolution of the z coordinate (perpendicular distance from detector plane) is SDD dependent with 95% confidence intervals of ±0.1, ±0.5, and ±2.0 mm at SDDs of 50, 100, and 150 mm, respectively. The response of the EPID is highly linear to dose rate. The EPID exhibits an over‐response to low energy incident photons and this nonlinearity is incorporated into the dose calibration procedure. A distance (spectral) dependent dose rate calibration procedure has been developed. The difference between measured and planned dose is less than 2% for 98.0% of pixels in a two‐dimensional plane at an SDD of 100 mm.

Conclusions:

Our application of EPID dosimetry to HDR brachytherapy provides a quality assurance measure of the geometrical distribution of the delivered dose as well as the source positions, which is not possible with any current HDR brachytherapy verification system.
A Carbon Nanotube Cable for a Space Elevator
Authors: Bochníček Zdeněk
Published: October 2013

In this paper the mechanical properties of carbon nanotubes are discussed in connection with the possibility to use them for the construction of a space elevator. From the fundamental information about the structure of a carbon nanotube and the chemical bond between carbon atoms, Young's modulus and the ultimate tensile strength are estimated. For this calculation only simple high school physics is necessary. The results, the same as known from experimental data, show that carbon nanotubes could be, at least hypothetically, a possible material for construction of a space elevator cable.
Moving Worked Problems to YouTube
Authors: Christensen Warren
Published: October 2013

This article has two goals: (1) To convince you that you should use web-based videos outside of class for the transmissive, but necessary, portions of your lectures, and (2) to convince you that you can do this yourself without an unreasonable burden of time or effort.
In Vitro
Activities of Eight Antifungal Drugs against 106 Waterborne and Cutaneous Exophiala Species
Authors: Najafzadeh M. J. , Saradeghi Keisari M. , Vicente V. A. , Feng P. , Shamsian S. A. A. , Rezaei-Matehkolaei A. , de Hoog G. S. , Curfs-Breuker I. , Meis J. F.
Published: October 2013

The
in vitro
activities of eight antifungal drugs against 106 clinical and environmental isolates of waterborne and cutaneous
Exophiala
species were tested. The MICs and minimum effective concentrations for 90% of the strains tested (
n
= 106) were, in increasing order, as follows: posaconazole, 0.063 μg/ml; itraconazole, 0.25 μg/ml; micafungin, 1 μg/ml; voriconazole, 2 μg/ml; isavuconazole, 4 μg/ml; caspofungin, 8 μg/ml; amphotericin B, 16 μg/ml; fluconazole, 64 μg/ml.
Antimicrobial Activity of Ceftolozane-Tazobactam Tested against Enterobacteriaceae and Pseudomonas aeruginosa with Various Resistance Patterns Isolated in U.S. Hospitals (2011-2012)
Authors: Farrell David J. , Flamm Robert K. , Sader Helio S. , Jones Ronald N.
Published: October 2013

Ceftolozane/tazobactam, a novel antimicrobial agent with activity against
Pseudomonas aeruginosa
(including drug-resistant strains) and other common Gram-negative pathogens (including most extended-spectrum-β-lactamase [ESBL]-producing
Enterobacteriaceae
strains), and comparator agents were susceptibility tested by a reference broth microdilution method against 7,071
Enterobacteriaceae
and 1,971
P. aeruginosa
isolates. Isolates were collected consecutively from patients in 32 medical centers across the United States during 2011 to 2012. Overall, 15.7% and 8.9% of
P. aeruginosa
isolates were classified as multidrug resistant (MDR) and extensively drug resistant (XDR), and 8.4% and 1.2% of
Enterobacteriaceae
were classified as MDR and XDR. No pandrug-resistant (PDR)
Enterobacteriaceae
isolates and only one PDR
P. aeruginosa
isolate were detected. Ceftolozane/tazobactam was the most potent (MIC
50/90
, 0.5/2 μg/ml) agent tested against
P. aeruginosa
and demonstrated good activity against 310 MDR strains (MIC
50/90
, 2/8 μg/ml) and 175 XDR strains (MIC
50/90
, 4/16 μg/ml). Ceftolozane/tazobactam exhibited high overall activity (MIC
50/90
, 0.25/1 μg/ml) against
Enterobacteriaceae
and retained activity (MIC
50/90
, 4/>32 μg/ml) against many 601 MDR strains but not against the 86 XDR strains (MIC
50
, >32 μg/ml). Ceftolozane/tazobactam was highly potent (MIC
50/90
, 0.25/0.5 μg/ml) against 2,691
Escherichia coli
isolates and retained good activity against most ESBL-phenotype
E. coli
isolates (MIC
50/90
, 0.5/4 μg/ml), but activity was low against ESBL-phenotype
Klebsiella pneumoniae
isolates (MIC
50/90
, 32/>32 μg/ml), explained by the high rate (39.8%) of meropenem coresistance observed in this species phenotype. In summary, ceftolozane/tazobactam demonstrated high potency and broad-spectrum activity against many contemporary
Enterobacteriaceae
and
P. aeruginosa
isolates collected in U.S. medical centers. Importantly, ceftolozane/tazobactam retained potency against many MDR and XDR strains.
Contribution of Six Flagellin Genes to the Flagellum Biogenesis of Vibrio vulnificus and
In Vivo
Invasion
Authors: Kim Soo Young , Thanh Xuan Tran Thi , Jeong Kwangjoon , Kim Seong Bin , Pan Sang O , Jung Che Hun , Hong Seol Hee , Lee Shee Eun , Rhee Joon Haeng
Published: October 2013

Vibrio vulnificus
is a halophilic pathogenic bacterium that is motile due to the presence of a single polar flagellum.
V. vulnificus
possesses a total of six flagellin genes organized into two loci (
flaFBA
and
flaCDE
). We proved that all six of the flagellin genes were transcribed, whereas only five (FlaA, -B, -C, -D, and -F) of the six flagellin proteins were detected. To understand roles of the six
V. vulnificus
flagellins in motility and virulence, mutants with single and multiple flagellin deletions were constructed. Mutations in
flaB
or
flaC
or the
flaCDE
locus resulted in a significant decrease in motility, adhesion, and cytotoxicity, whereas single mutations in the other flagellin genes or the
flaFBA
locus showed little or no effect. The motility was completely abolished only in the mutant lacking all six flagellin genes (
flaFBA flaCDE
). Surprisingly, a double mutation of
flaB
and
flaD
, a gene sharing 99% identity with the
flaB
at the amino acid level, resulted in the largest decrease in motility, adhesion, and cytotoxicity except for the mutant in which all six genes were deleted (the hexa mutant). Additionally, the 50% lethal doses (LD
50
s) of the
flaB flaD
and the
flaFBA flaCDE
mutants increased 23- and 91-fold in a mouse model, respectively, and the
in vitro
and
in vivo
invasiveness of the mutants was significantly decreased compared to that of the wild type. Taken together, the multiple flagellin subunits differentially contribute to the flagellum biogenesis and the pathogenesis of
V. vulnificus
, and among the six flagellin genes,
flaB
,
flaD
, and
flaC
were the most influential components.