bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid High Temperature Solar Thermal Biomass Gasification in a Prototype Cavity Reactor
Authors: Lichty Paul , Perkins Christopher , Woodruff Bryan , Bingham Carl , Weimer Alan
Published: October 2010

High temperature biomass gasification has been performed in a prototype concentrated solar reactor. Gasification of biomass at high temperatures has many advantages compared to historical methods of producing fuels. Enhancements in overall conversion, product composition ratios, and tar reduction are achievable at temperatures greater than 1000°C. Furthermore, the utilization of concentrated solar energy to drive these reactions eliminates the need to consume a portion of the product stream for heating and some of the solar energy is stored as chemical energy in the product stream. Experiments to determine the effects of temperature, gas flow rate, and feed type were conducted at the High Flux Solar Furnace (HFSF) at the National Renewable Energy Laboratory (NREL). These experiments were conducted in a reflective cavity multi-tube prototype reactor. Biomass type was found to be the only significant factor within a 95% confidence interval. Biomass conversion as high as 68% was achieved on sun. Construction and design considerations of the prototype reactor are discussed as well as initial performance results.
Airfoil Selection for a Straight Bladed Circulation Controlled Vertical Axis Wind Turbine
Authors: Graham Henry Z. , Panther Chad , Hubbell Meagan , Wilhelm Jay P. , Angle Gerald M. , Smith James E.
Published: October 2010

A vertical axis wind turbine (VAWT) prototype is being developed at West Virginia University that utilizes circulation control to enhance its performance. An airfoil was chosen for this turbine based on its performance potential, and ability to incorporate circulation control. The selection process for the airfoil involved the consideration of camber, blade thickness, and trailing edge radius and the corresponding impact on the lift and drag coefficients. The airfoil showing the highest lift/drag ratio augmentation, compared to the corresponding unmodified airfoil was determined to be the most likely shape for use on the circulation control augmented vertical axis wind turbine. The airfoils selected for this initial investigation were the NACA0018, NACA2418, 18% thick elliptical, NACA0021, and the SNLA2150. The airfoils were compared using the computational fluid dynamics program FLUENT v.6.3.26 with a blowing coefficient of 1% [1]. The size of the trailing edge radius and the slot heights were varied based on past experimental data [2]. The three trailing edge radii and two blowing slot heights were investigated. The thickness of the airfoil impacts the circulation control performance [3], thus it was studied by scaling the NACA0018 to a 21% thickness and compared to an SNLA2150 airfoil. The airfoils’ lift and drag coefficients were compared to determine the most improved lift-drag ratio (L/D). When comparing the increases of the L/D due to circulation control, the NACA0018 and 2418 airfoils were found to outperform the elliptical airfoil; the NACA0018 performed slightly better than the 2418 when comparing the same ratio L/D. The results showed that the 21% thick airfoils produced a decreased L/D profile compared to the NACA0018 airfoils. Therefore, the NACA0018 was found to be the optimal airfoil based from this initial investigation due to an increased L/D compared to the other airfoils tested.
Experimental Daily Energy Performance of Flat Plate and Evacuated Tube Solar Collectors
Authors: Zambolin Enrico , Del Col Davide , Padovan Andrea
Published: October 2010

New comparative tests on different types of solar collectors are presented in this paper. Tests have been performed at the solar energy conversion laboratory of the University of Padova. Two standard glazed flat plate collectors and one evacuated tube collector are installed in parallel; the evacuated collector is a direct flow through type with external CPC (compound parabolic concentrator) reflectors. The present test rig allows to make measurements on the flat plate, on the evacuated collector or on both simultaneously, by simply acting on the valves to modify the circuit. In this paper measurements of the performance of the evacuated tube collector and flat plate collectors working at the same conditions are reported. Efficiency in stationary conditions is measured following the standard EN 12975-2 [1] and it is compared with the input/output curves measured for an entire day. The main purpose of the present work is to characterize and to compare the daily energy performance of the two types of collectors. An effective mean for describing and analyzing the daily performance is the so called input/output diagram, in which the collected solar energy is plotted against the daily incident solar radiation. Test runs have been performed in several conditions to reproduce different conventional uses (hot water, space heating, solar cooling).
Vortex Analytical Model of a Circulation Controlled Vertical Axis Wind Turbine
Authors: Wilhelm Jay P. , Panther Chad C. , Pertl Franz A. , Smith James E.
Published: October 2010

A possible method for modeling a Circulation Controlled - Vertical Axis Wind Turbine (CC-VAWT) is a vortex model, based upon the circulation of a turbine blade. A vortex model works by continuously calculating the circulation strength and location of both free and blade vortices which are shed during rotation. The vortices’ circulation strength and location can then be used to compute a velocity at any point in or around the area of the wind turbine. This model can incorporate blade wake interactions, unsteady flow conditions, and finite aspect ratios. Blade vortex interactions can also be studied by this model to assist designers in the avoidance of adverse turbulent operational regions. Conventional vertical axis wind turbine power production is rated to produce power in an operating wind speed envelope. These turbines, unless designed specifically for low speed operation require rotational start-up assistance. The VAWT blade can be augmented to include circulation control capabilities. Circulation control can prolong the trailing edge separation and can be implemented by using blowing slots located adjacent to a rounded trailing edge surface; the rounded surface of the enhanced blade replaces the sharp trailing edge of a conventional airfoil. Blowing slots of the CC-VAWT blade are located on the top and bottom trailing edges and are site-controlled in multiple sections along the span of the blade. Improvements in the amount of power developed at lower speeds and the elimination or reduction of start-up assistance could be possible with a CC-VAWT. In order to design for a wider speed operating range that takes advantage of circulation control, an analytical model of a CC-VAWT would be helpful. The primary function of the model is to calculate the aerodynamic forces experienced by the CC-VAWT blade during various modes of operation, ultimately leading to performance predictions based on power generation. The model will also serve as a flow visualization tool to gain a better understanding of the effects of circulation control on the development and interactions of vortices within the wake region of the CC-VAWT. This paper will describe the development of a vortex analytical model of a CC-VAWT.
Exergoeconomic Analysis of District Heating Systems
Authors: Verda Vittorio , Fausone Serena
Published: October 2010

District heating is a rational way to use fossil fuels for domestic heating (and cooling) in towns, especially if it is joined to a cogenerative production of electricity. The aim of this paper is to propose the use of exergoeconomic procedures for the design and analysis of district heating systems. Network design basically involves the selection of the areas to be connected to the network as well as the selection of some design variables as the pipe diameters, the location of pumps etc. This choice is operated assuming primary energy consumption as the objective function to be minimized. The application of these concepts is operated through a probabilistic approach derived from Simulated Annealing. An application to the Turin district heating system is presented here. The system is composed of a cogenerative combined cycle, some auxiliary boilers and the pipe network. An exergetic cost is associated to each user or potential user. This information is used to evaluate the opportunities for future expansions of the served area as well as the variation in some of the operating parameters.
A Small-Scale Solution for a Big Energy Problem: Renewable Distributed Energy
Authors: Comly Renee , Mathew Alex
Published: October 2010

A Small-Scale Solution for a Big Energy Problem: Renewable Distributed Energy. Locally generated biomass, industrial and municipal wastes, coal and plastics have a significant part to play in providing a source of reliable and economic energy in the US. The ability to use these materials reliably and cleanly can be addressed with small-scale gasification technology to provide distributed generation. A technology that has improved on the historical success of gasification to provide these elements is TURNW2E™ Gasification. This technology is specifically designed to convert locally available energy resources into a clean fuel gas which is then subsequently used for heat and or power generation. This technology has the ability to operate cleanly and interchangeably using waste materials and /or coal. With the ability to produce power economically from 100 kW to 5 MW it can provide distributed generation at institutions, DOD facilities, and industrial complexes. This creates a reliable and economical energy source for the user, while disposing of wastes in an environmentally sound manner. This replaces landfill use with the energy transformation process of gasification, which provides enormous environmental benefits, including the elimination of carcinogens and reduction of greenhouse gas emissions caused by incineration processes. The use of renewable biomass and wastes provides a sustainable source of electricity that is unrestricted by grid access, providing tremendous potential to reduce US fuel imports. Using this approach, the user can create jobs and power in a sustainable scenario; without sending precious energy dollars overseas, using this process in a distributed manner will help strengthen our nation’s economy, and provide improvements to the quality of life wherever it is installed. By having the ability to use many different feedstocks, the technology can enable the avoidance of landfilling MSW and industrial wastes, including tires; it can use waste wood such as railroad ties, beetle-infested pine, and forestry wastes, farm wastes and natural disaster debris to generate renewable energy for local use or sale to the grid. Materials for processing are varied, and thus, the technology flexibility enables small-scale use in a wide range of installations, a landfill site, transfer station, farm, hospital, manufacturing facility, resort, DOD base, island community, university, and local municipal site. TURNW2E™ Gasification is available at commercial scale and is currently installed at two facilities overseas, with three US facilities planned for ’09. A training and continuing education /R&D facility is underway in the US.
Control and Optimization of a Simulated Hydrogen Production Operation
Authors: Chamorro Ramiro J. , Sanjuan Marco E.
Published: October 2010

This research presents an approach for modeling and control of a hydrogen production plant based in steam reforming of methane (SRM). Many studies in the literature have established some important hydrogen production plant information related to sizing and optimization. This research shows a dynamic model integrated with an industrial control system, which will be able to represent the unified plant data for process variables (temperature, pressure, size, etc.). The plant was optimized using surface response methodology (SRM) to approach a maximum value of hydrogen and a minimum carbon monoxide concentration. The dynamic plant model exhibited high interactions and nonlinear behavior. Hence, a Model predictive control (MPC) strategy was design for the dynamic case, with very good results due to its centralized control structure. Steady-state and dynamic simulations were developed using HYSYS 2006.
Electrical and CHP Efficiencies of a 1 MW University Fuel Cell Power Plant
Authors: Ryan Robert
Published: October 2010

A 1 MW fuel cell power plant began operation at California State University, Northridge (CSUN) in January, 2007. The power plant was installed on campus to complement a Satellite Chiller Plant which is being constructed in response to increased cooling demands related to campus growth. The power plant consists of four 250 kW fuel cell units, and a waste heat recovery system which produces hot water for the campus. The waste heat recovery system was designed by CSUN’s Physical Plant Management personnel, in consultation with engineering faculty and students, to accommodate the operating conditions required by the fuel cell units as well as the thermal needs of the campus. A unique plenum system, known as a Barometric Thermal Trap, was created to mix the four fuel cell exhaust streams prior to flowing through a two stage heat exchanger unit. The two stage heat exchanger uses separate coils for recovering sensible and latent heat in the exhaust stream. The sensible heat is being used to partially supply the campus’ building hot water and space heating requirements. The latent heat is intended for use by an adjacent recreational facility at the University Student Union. This paper discusses plant performance data which was collected and analyzed over a several month period during 2008. Electrical efficiencies and Combined Heat and Power (CHP) efficiencies are presented. The data shows that CHP efficiencies have been consistently over 60%, with the potential to exceed 70% when planned improvements to the plant are completed.
Thermodynamic Considerations for the Design of Solar-Thermal Chemical Processes
Authors: Martinek Janna , Channel Melinda , Lewandowski Allan , Weimer Alan W.
Published: October 2010

The maximum efficiency of a solar reactor/receiver is limited not by the Carnot efficiency, but rather by the product of the Carnot efficiency and a factor involving both the enthalpy and entropy changes occurring as a result of the chemical reaction. This limiting efficiency can be greater than the Carnot efficiency when the entropy change is positive, and is a function of several parameters including the standard property changes of the reaction, inlet and outlet stream conditions, reactor temperature, conversion, and relative amounts of inert gas. By including this factor in the overall limitation on the reactor efficiency, both the optimal reactor temperature for a given concentration ratio, and the concentration ratio required to achieve a given temperature and efficiency can, in many cases, be found to shift to lower values.
Effect of Distributed Power Conversion on the Annual Performance of Building-Integrated PV Arrays With Complex Roof Geometries
Authors: MacAlpine Sara M. , Brandemuehl Michael J. , Linares Leonor L. , Erickson Robert W.
Published: October 2010

Building-integrated photovoltaic (BIPV) systems have gained greater popularity in recent years; however, their effectiveness is often limited by nonuniform operating conditions. To increase potential for energy capture in PV systems, particularly those with series string configurations, an improved module integrated dc-dc converter (MIC) with maximum power point tracking has been proposed. This paper investigates the potential power gain provided by these MICs in situations where the architecture or surroundings of a building necessitate that a PV array include panels with differing orientations, which can significantly reduce system efficiency. A flexible, comprehensive simulation model for BIPV systems is developed, which allows for variations in insolation and temperature at the PV cell level, while accurately modeling MICs and their effect on array performance. This model is used to simulate various directional array combinations in series string and parallel configurations for a representative set of climates around the US. Results of these simulations show power gains attributed to both the photovoltaic generator/converter portion of the system and to increased inverter efficiency arising from a constant, controlled string voltage. When differing panel orientations within an array are considered, there is potential for annual power output gains of over 10% for a system with MICs when compared to conventional approaches. Further opportunities for increased energy capture in a BIPV system with MICs are identified and discussed.
Numerical Modeling of Vapor Condensation During Cadmium Quenching Process in a Solar Receiver
Authors: Nie Jianhu , Chen Yitung , Wong Bunsen , Brown Lloyd C.
Published: October 2010

Cadmium quencher is an important equipment for the high efficiency generation of hydrogen fuel using solar thermochemical splitting of water. In order to effectively guide the design of solar decomposer and vapor quencher, it is of critical importance to understand the mechanisms of transport phenomena inside them. The mixture model was selected for modeling the multiphase flow, and the two-equation RNG k-ε model was used to model the turbulent flow and heat transfer. Numerical results showed that flowrate of the quencher air directly influences the velocity, temperature and mole fraction of cadmium vapor inside the decomposer and quencher. The developed CFD model can be used to guide the design of efficient solar receiver and cadmium decomposer/quencher.
A Discussion of the Measurement of Zn to ZnO Conversion in Aerosol Reactors
Authors: Haltiwanger Julia F. , Venstrom Luke J. , Davidson Jane H.
Published: October 2010

One approach proposed for the exothermic step of the solar Zn/ZnO thermochemical water-splitting cycle is synthesis and hydrolysis of Zn nanoparticles in an aerosol reactor. To date the most common method to quantify the extent of conversion from Zn to ZnO is ex-situ X-ray diffraction analysis of particles collected on a filter placed at the exit of the reactor. The assumption inherent in this approach is that captured particles do not react on the filter because of its relatively low temperature. In the present study, we assess this assumption using data collected on hydrolysis of Zn nanoparticles at temperatures between 360 and 465 K and discuss methods of quantitative analysis via X-ray diffraction (XRD). Zn nanoparticles synthesized via condensation in an argon carrier gas are captured on a filter. Once the particles are collected, steam is introduced to the reactor at controlled partial pressure and temperature. The extent of reaction at the filter is characterized via calibrated XRD. At and below 380 K the reaction is negligible. At 465 K, the rate of conversion is slow at 0.007 ± 0.001%/min. In most cases, quantifying the extent of conversion from Zn to ZnO in the aerosol by ex-situ X-ray diffraction analysis of particles collected on the filter is an acceptable approach, though care should be taken in both the application of this method and in the quantitative analysis of the XRD data.
Thermal Performance of a Combined Heat, Cooling, and Power Microturbine System
Authors: Ja¨a¨skela¨inen Hannu E. , Wallace James S.
Published: October 2010

A 240 kWe integrated microturbine chiller/heater system was installed on the campus of the University of Toronto at Mississauga in 2005 to provide heating or cooling in combination with electric power generation. The system consists of four 60 kWe microturbines fueled by natural gas and a 110 ton lithium bromide absorption chiller that utilizes waste heat from the microturbines. The chiller can be operated in cooling mode to supply chilled water in summer for cooling or in heating mode to supply hot water (60°C) in winter for heating. Tests were conducted in both heating and cooling mode to evaluate the effectiveness of heat recovery and results are presented for both modes of operation. However, operating constraints imposed by this particular installation prevent full utilization of thermal output in both heating and cooling mode. Recommendations are provided to guide future installations to make full use of the equipment’s potential.
Design of Optimization of CIGS Thin Film Solar Cell Using Numerical and Design of Experimental Approach
Authors: Seok Ilwoo , Dhage Sanjay , Kim Seongku , Hahn H. T.
Published: October 2010

Design of optimization of thin film solar cell module based on Cu(In,Ga)Se2 (CIGS) is investigated through a simulation model. At first, a numerical model which is equivalent to a practical cell module and represents one diode electrical circuit method is sought in FEA (Finite Element Analysis) and several parameters are adjusted. In FEA, the distribution of electric potential within each layer is shown with accordance to the given inputs. Next, to find the optimal design, four design variables (factors) which have three levels each are chosen and Design of Experimental (DOE) is performed so that the order of influences to performance is arranged. In DOE, a series of simulation follows the prepared orthogonal array, which is a sort of combinations by factors and levels, then analysis of variance (ANOVA) table is built up to screen unimportant design variables. Finally, the surface response function, which represents the relationship between important design variables and the purposed performance such as efficiency and fill factor (FF), is found and shown into equipotential graphs.
Economic Analysis of an Integrated Anthropogenic Carbon Dioxide Network for Capture and Enhanced Oil Recovery Along the Texas Gulf Coast
Authors: King Carey W. , Gu¨len Gu¨rcan , Essandoh-Yeddu Joseph , Hovorka Susan
Published: October 2010

This paper explains the system economics of an example integrated network that uses anthropogenic CO2 from Texas Gulf Coast fossil power plants for enhanced oil recovery (EOR). These CO2 sources and sinks are connected via a pipeline network. A discounted cash flow model indicates that for all candidate oil fields that require less than an estimated $10/BBL in EOR capital expenditure, all three entities (CO2 capture, pipelines, and EOR operators) can have 20% internal rate of return at $55 per tonne of CO2 and $56 per barrel of oil. These results include no existing or future tax incentives, and there are some costs not yet included. However, a Monte Carlo analysis shows insight by indicating that the total system rate of return is most sensitive to oil production parameters. Oil price and estimated amount of recoverable oil are the most positively influential factors while the EOR capital cost is the most negatively sensitive factor. The capital costs of capture and CO2 price are less sensitive, both negatively affecting rate of return.
Solar H2 Production With Tokyo Tech Rotary-Type Solar Reactor to be Tested Using Solar Concentration System at CSIRO in Australia
Authors: Kaneko Hiroshi , Lee Chong-il , Ishikawa Yosuke , Hosogoe Koichiro , Tamaura Yutaka
Published: October 2010

The test operation of the Tokyo Tech rotary-type solar reactor (2nd model) is scheduled to be carried out using the solar concentrating system of CSIRO (New castle, Australia) as an international collaboration research between Japan (Tokyo Tech) and Australia (CSIRO) in APP (Asia-Pacific Partnership on Clean Development and Climate) project. The rotary-type solar reactor is positioned at an elevation of about 17 m. The input of solar power for the test operation is planned to be 50 kW from the solar concentrating system with about 10 heliostats. The estimation of evolved H2 gas was calculated from the amount of evolved O2 gas and the energy conversion efficiency is evaluated from the estimated amount of evolved H2 gas and the input of solar energy. The two-step water splitting process with the reactive ceramics of ceria-based solid solution (0.8CeO2−0.2ZrO2 prepared by the polymerized complex method) was investigated using the solar simulator of concentrated Xe lamp beams for the test operation of the rotary-type solar reactor at CSIRO solar concentrating system. The amounts of O2 and H2 gases evolved in the two-step water splitting reaction with CeO2-ZrO2 solid solution were determined for the H2-generation reaction temperatures of 773, 1273 and 1473 K. The amounts of evolved H2 gas decreased with an increase of the reaction temperature, however, the lowering of H2 gas evolution at 1473 K was 20% in comparison with that at 773 K. The heating time of the reactive ceramics up to the O2-releasing reaction temperature is evaluated to 3 s, when the difference between the O2-releasing reaction temperature (1773 K) and the H2-generation reaction temperature (1473 K) is 300 K.
Energy Storage Analysis to Increase Large Ship Fuel Efficiency
Authors: Gully Benjamin H. , Webber Michael E. , Seepersad Carolyn C. , Thompson Richard C.
Published: October 2010

The marine transportation industry is a significant contributor to global emissions of CO2 and other pollutants. Although marine emission standards have become increasingly stringent, increasing fuel efficiency remains the primary objective in terms of further reducing emissions and overall marine energy use. In this paper, a hybrid powertrain is investigated as a means of increasing fuel efficiency for a modern, 100 m class, passenger vessel. The hybrid powertrain includes an Energy Storage System (ESS) based on sodium sulfur (NaS) batteries and commercially available Caterpillar diesel engine-generator sets. The ship’s power load profile is based on annual averages for similar vessels. A control strategy and simulation models are developed and implemented in Simulink to analyze the power and energy flows in the hybrid powertrain. The Simulink model is used to compare the base scenario of a ship without energy storage to a hybrid scenario employing a 7.5 MWh NaS battery pack with related control strategy. Annual fuel consumption is the primary measure that is used to assess efficiency. Unlike hybrid powertrains for light-duty surface vehicle transportation, which achieve efficiency gains on the order of 10–20% [8, 9, 10], the hybrid powertrain for a large ship is estimated to lower annual fuel consumption by approximately 2%. The surprisingly small level of fuel savings is explained largely by the granularity of marine power systems, which include multiple generators that can be switched on and off to maximize fuel efficiency.
Comparative Energy Analysis of VRF and VAV Systems Under Cooling Mode
Authors: Koh Jaeyoon , Zhai John Z. , Rivas Jessica A.
Published: October 2010

Variable refrigerant flow (VRF) or variable refrigerant volume (VRV) systems provide many benefits over traditional air-conditioning systems, with great potential to decrease energy cost and increase thermal comfort in buildings. This paper presents a method to size and select VRF systems and to compute its annual energy consumption. The study compares the cooling energy usage of a VRF system against a conventional chiller-based variable-air-volume (VAV) system and a packaged VAV (PVAV) system for a typical light commercial building. The results reveal that the peak electrical demand of the VRF system for the cooling season is about 60% of the chiller-based VAV system and 70% of the packaged VAV systems, and the operating energy usage is about 53% of the chiller-based VAV system and 60% of the packaged VAV system for the building studied.
An Heuristic Approach to Renewable Energy Optimization
Authors: Walker Andy
Published: October 2010

An analytical approach is often taken to predict the performance of renewable energy systems at a site, but an analytic approach requires detailed information on the system to be modeled that is better determined during schematic design than guessed-at during pre-design. This paper describes a heuristic approach to identify and prioritize renewable energy project opportunities before detailed system information is available. The method determines the combination of renewable energy technologies that minimize life-cycle cost at a facility, often with a specified goal regarding percent of energy use from renewable sources. Technologies include: photovoltaics (PV); wind; solar thermal heat and electric; solar ventilation air preheating; solar water heating; biomass heat and electric (combustion, gasification, pyrolysis, anaerobic digestion); and daylighting. The method rests upon the National Renewable Energy Laboratory’s (NREL) capabilities in: characterizing of the empirical cost and performance of technologies; geographic information systems (GIS) resource assessment; and life-cycle cost analysis. For each technology, simple heuristic algorithms relate renewable energy resources at a site to annual energy delivery with coefficients that are determined empirically. Initial cost and operation and maintenance (O&M) cost also use empirical data. Economic performance is then calculated with a site’s utility rates and incentives. The paper discusses how to account for the way candidate technologies interact with each other, and the solver routine used to determine the combination that minimizes lifecycle cost. Results include optimal sizes of each technology, initial cost, operating cost, and life-cycle cost, including incentives from utilities or governments. Results inform early planning to identify and prioritize projects at a site for subsequent engineering and economic feasibility study. Case studies include industrial sites, military bases, and civic buildings.
Investigation of Nanofluids for Solar Thermal Storage Applications
Authors: Shin Donghyun , Banerjee Debjyoti
Published: October 2010

Nanofluids are synthesized by doping solvents with nano-particles at minute concentrations (typically less than 1 percentage by volume). Experimental studies have shown that nano-particles can dramatically enhance the specific heat of various liquid solvents. This is also associated with enhancement of other transport properties (e.g., viscosity, thermal conductivity, diffusivity, etc.). Hence, nanofluids are attractive materials for solar thermal applications. The objective of this study is to investigate the optimum performance of various nanofluids for solar thermal storage applications. Dimensional analyses and similitude techniques will be used to theoretically estimate the enhancement of transport properties of various nanofluids to predict their efficacy for solar thermal storage applications.
Methodolgy for Preliminary Assessment of Regional Wind Energy Potential
Authors: Wenning Thomas J. , Kissock J. Kelly
Published: October 2010

This paper describes a methodology for a preliminary assessment of a region’s wind energy potential. The methodology begins by discussing four primary considerations for site location: wind resources, wildlife corridors, proximity to transmission grids, and required land area. Algorithms to calculate wind energy production using both hourly and annual average wind speed are presented. The hourly data method adjusts for differences in height, air density and terrain effects between the measurement site and the proposed turbine site. The annual average wind data method adjusts for these factors, and uses the average annual wind speed to generate a Rayleigh distribution of wind speeds over the year. Wind turbine electricity generation is calculated using the wind speed data and the turbine power curve. The lifecycle cost of electricity is calculated from operating costs, purchase costs, a discount rate, and the project lifetime. A case study demonstrates the use of the methodology to investigate the potential for producing electricity from wind turbines in Southwest Ohio. This information is useful to utilities, power producers and municipalities as they look to incorporate renewable energy generation into their portfolios.
Impact of Layered Soil on Foundation Heat Transfer for Slab-On Grade Floors
Authors: Khaled Nizar , Krarti Moncef
Published: October 2010

This paper presents an analytical solution for the steady-periodic heat transfer for a typical slab-on-grade floor building foundation beneath non-homogeneous soil medium. The impact of the above-grade walls on ground-coupled heat transfer is accounted for in the presented solution. The Inter-zone Temperature Estimation Profile (ITPE) technique is utilized to obtain the 3-D solutions to determine soil temperature distributions and to estimate foundation heat loss/gain from slab-on-grade floors. The impact of the non-homogeneous soil properties on the transient foundation heat transfer is investigated for various slab configurations and soil thermal properties.
Reliability Analysis of Wind Turbines
Authors: DeVoto Douglas , McCluskey Patrick
Published: October 2010

This paper investigates the efforts to improve the reliability of wind turbines through the physics-of-failure based approach. Critical subassemblies of modern wind turbines are highlighted and their current reliability is reported. The application of the physics-of-failure based reliability assessment is presented for improving the performance of a wind turbine’s blades, gearbox, and converter subassemblies.
Assessment of Solar Power Tower Driven Ultra Supercritical Steam Cycles Applying Tubular Central Receivers With Varied Heat Transfer Media
Authors: Singer Cs. , Buck R. , Pitz-Paal R. , Mu¨ller-Steinhagen H.
Published: October 2010

In commercial power plant technology, the market introduction of ultra supercritical (USC) steam cycle power plants with steam parameters around 350bar and 720°C is the next development step. USC steam cycles are also proposed to decrease the levelized electricity costs of future solar power towers due to their highly efficient energy conversion. A 55% thermal efficiency with decreased specific investment costs is within the potential of USC steam cycles. The required process parameters can be achieved using nickel based alloys in the solar receiver, the tubing and other plant components. For solar tower applications, appropriate high temperature heat transfer media (HTM), high temperature heat exchangers and storage options are additionally required. Using the current development for molten salt power towers (Solar Tres) as a reference, several tower concepts with USC power plants were compared. The ECOSTAR methodology provided by [1] was applied for predicting the cost reduction potential and the annual performance of these power tower concepts applying tubular receivers with various HTM. The considered HTM include alkali nitrate salts, alkali chloride salts and liquid metals such as a Bi-Pb eutectic, tin or sodium. For the assessment, an analytical model of the heat transfer in a parametric 360° cylindrical, tubular central receiver was developed to examine the receiver characteristics for different geometries. The sensitivity of the specific cost assumptions for the levelized electricity costs (LEC) was evaluated for each concept variation. No detailed evaluation was done for the thermal storage, but comparable costs were assumed for all cases. The results indicate a significant cost reduction potential for the liquid metal HTM processes.
The Design and Fabrication of an Alternative Drive System to Reduce Heliostat Manufacturing and Installation Costs
Authors: Chavez Kyle , Sproul Evan , Christian Joshua , Valdez Kendra , Luders Ian , Lucero Derek , Sroges Walker , DeOreo Victoria
Published: October 2010

The limited supply and environmental impact of fossil fuels has become an urgent problem. To aid in overcoming this problem a team from New Mexico Tech (NMT) is improving existing heliostat technology to create a more cost-effective and mobile heliostat design. The team has devised an innovative patent pending liquid-ballast heliostat drive system which reduces the cost of heliostat drive mechanics, utilizes a cost-effective mirror design, and eliminates an unnecessary support pedestal. By implementing this new design the team will help to create a more economically viable, clean energy source that will benefit all energy consumers as well as the environment. The team’s goal is to create a heliostat that reduces the cost of production and operation by thirty percent. In doing so, the team must also meet strict accuracy and lifetime specifications created by Sandia National Labs (SNL) and NMT. In pursuit of meeting these specifications the team is currently completing fabrication of a prototype. Using this prototype the team will evaluate drive system performance through semi-automated testing. After testing, the team will continue the design process with the ultimate goal of creating multiple improved prototypes.
Apolipoprotein E Controls ATP-Binding Cassette Transporters in the Ischemic Brain
Authors: ElAli Ayman , Hermann Dirk M.
Published: October 2010

Apolipoprotein E regulates ATP-binding cassette drug transporters in the ischemic brain, thereby controlling the brain-to-blood drug distribution.
SLAMming Bacteria
Authors: Wong Wei
Published: October 2010

A receptor family previously characterized as adhesion and costimulatory molecules also acts as sensors for gram-negative bacteria.
No Intermediates Needed
Authors: Gough Nancy R.
Published: October 2010

The type 1 transforming growth factor–β receptor phosphorylates elongation factor eEF1A1 to inhibit translation.
Mechanical Responders Identified
Authors: Ray L. Bryan
Published: October 2010

Cation channel genes encode for a transducer molecule that converts mechanical stimuli into cell signaling.
Serotype Distribution and Susceptibility of
Streptococcus pneumoniae
Isolates from Pleural Fluid in Spain from 1997 to 2008
Authors: Fenoll A. , Aguilar L. , Vicioso M. D. , Gimenez M. J. , Robledo O. , Granizo J. J. , Mendez C.
Published: October 2010

Trends in serotype incidence and susceptibility (1997 to 2008) of Spanish
Streptococcus pneumoniae
pleural isolates (
n
= 831) were explored. Penicillin (oral) nonsusceptibility rates and the incidence of 7-valent pneumococcal conjugate vaccine (PCV-7) serotypes showed decreasing trends (
R
2
≥ 0.600;
P
≤ 0.002). The incidence of serotypes 1 and 19A showed increasing trends (
R
2
≥ 0.759;
P
< 0.001), with no trends for serotype 3. Serotypes 19A, 1, and 3 represented 85% of pediatric isolates in 2008. In serotype 19A, the penicillin nonsusceptibility rate was 82.4% in 2008, associated with amoxicillin and cefotaxime nonsusceptibility in 21.4% of isolates. Inclusion of these serotypes in new vaccines offers the broadest coverage.
In Vivo
Pharmacodynamic Activity of Tomopenem (formerly CS-023) against
Pseudomonas aeruginosa
and Methicillin-Resistant
Staphylococcus aureus
in a Murine Thigh Infection Model
Authors: Sugihara Kiyoshi , Sugihara Chika , Matsushita Yoko , Yamamura Naotoshi , Uemori Mitsutoshi , Tokumitsu Akane , Inoue Harumi , Kakuta Masayo , Namba Eiko , Nasu Hatsumi , Koga Tetsufumi
Published: October 2010

Tomopenem (formerly CS-023) is a novel carbapenem with broad-spectrum activities against diverse hospital pathogens, including
Pseudomonas aeruginosa
and methicillin-resistant
Staphylococcus aureus
(MRSA). We examined the
in vivo
pharmacodynamic characteristics of tomopenem against
P. aeruginosa
and MRSA by using a neutropenic murine thigh infection model with
P. aeruginosa
12467 (MIC, 1 μg/ml) and MRSA 12372 (MIC, 2 μg/ml). The mice had 10
6
to 10
7
CFU/thigh of each strain 2 h after inoculation and were treated for 24 h with a fractionated administration of tomopenem given at intervals of 3, 6, 12, and 24 h. The serum protein binding of tomopenem was 17.4%. The efficacy of tomopenem in both infection models was enhanced by frequent dosing, which indicates that the efficacy is driven by the time above MIC (
T
MIC
). In a sigmoid model, the cumulative percentages of the 24-h period that the concentrations of free, unbound fractions of the drug exceeded the MIC under steady-state pharmacokinetic conditions (
f
%
T
MIC
s) were best correlated with efficacy when
R
2
was 0.79 and 0.86 against
P. aeruginosa
and MRSA, respectively. Other pharmacokinetic and pharmacodynamic (PK-PD) indexes for the free, unbound fractions, the area under the concentration-time curve over 24 h in the steady state divided by the MIC (AUC/MIC) and the maximum concentration of the drug in serum divided by the MIC (
C
max
/MIC), showed poor correlation with efficacy when
R
2
was ≤0.42. The
f
%
T
MIC
values required for a static effect, 1-log kill, and 2-log kill against
P. aeruginosa
were 29, 39, and 51, respectively, which were similar to those for meropenem, for which the values were 24, 33, and 45, respectively. Against MRSA, the values for tomopenem were 27, 35, and 47. In conclusion, the pharmacodynamic characteristics of tomopenem were similar to those of meropenem against
P. aeruginosa
, and there was no difference between the target values for
P. aeruginosa
and MRSA required for efficacy in this study.
In Vitro
Evaluation of Viability, Integrity, and Inflammation in Genital Epithelia upon Exposure to Pharmaceutical Excipients and Candidate Microbicides
Authors: Gali Youssef , Delezay Olivier , Brouwers Joachim , Addad Noura , Augustijns Patrick , Bourlet Thomas , Hamzeh-Cognasse Hind , Ariën Kevin K. , Pozzetto Bruno , Vanham Guido
Published: October 2010

The use of microbicides is a promising approach for the prevention of HIV-1 transmission. Unfortunately, various candidates failed in clinical trials. In some cases, the candidate microbicide even resulted in enhanced virus transmission. Therefore, there is an urgent need to develop more predictive preclinical strategies to anticipate the
in vivo
efficiency/toxicity rate, including
in vitro
assays that evaluate effects on epithelial integrity and inflammation. The present study aims to identify potential safety issues concerning the use of microbicides and excipients commonly used in vaginal microbicide preparations. The toxicities of various active pharmaceutical ingredients (APIs; TMC-120, UC-781, tenofovir [PMPA], PRO-2000, and glycerol monolaurate [GML]) and excipients (preservatives, cosolvents, surfactants, and cyclodextrins) were evaluated using an
in vitro
dual-chamber model and uterine cervical explants. Epithelial viability and permeation of fluorescent virus-sized beads, as well as induction of interleukin-8 (IL-8; as a sensitive marker of an inflammatory response), were assessed. Surprisingly, cell viability and epithelial layer integrity were compromised by most excipients at concentrations near the typical concentration used in vaginal gels, and a significant increase in the production of IL-8 was observed at subtoxic concentrations. Within the APIs, TMC-120, UC-781, and PMPA showed higher selectivity indices than PRO-2000 and GML. In conclusion, identification of safety issues concerning the use of pharmaceutical excipients could help to formulate less toxic vaginal microbicide preparations.
Mechanistic Studies of the Inactivation of TEM-1 and P99 by NXL104, a Novel Non-β-Lactam β-Lactamase Inhibitor
Authors: Stachyra Thérèse , Péchereau Marie-Claude , Bruneau Jean-Michel , Claudon Monique , Frère Jean-Marie , Miossec Christine , Coleman Kenneth , Black Michael T.
Published: October 2010

NXL104 is a potent inhibitor of class A and C serine β-lactamases, including KPC carbapenemases. Native and NXL104-inhibited TEM-1 and P99 β-lactamases analyzed by liquid chromatography-electrospray ionization-time of flight mass spectrometry revealed that the inactivated enzymes formed a covalent adduct with NXL104. The principal inhibitory characteristics of NXL104 against TEM-1 and P99 β-lactamases were determined, including partition ratios, dissociation constants (
K
), rate constants for deactivation (
k
2
), and reactivation rates. NXL104 is a potent inhibitor of TEM-1 and P99, characterized by high carbamylation efficiencies (
k
2
/
K
of 3.7 × 10
5
M
−1
s
−1
for TEM-1 and 1 × 10
4
M
−1
s
−1
for P99) and slow decarbamylation. Complete loss of β-lactamase activity was obtained at a 1/1 enzyme/NXL104 ratio, with a
k
3
value (rate constant for formation of product and free enzyme) close to zero for TEM-1 and P99. Fifty percent inhibitory concentrations (IC
50
s) were evaluated on selected β-lactamases, and NXL104 was shown to be a very potent inhibitor of class A and C β-lactamases. IC
50
s obtained with NXL104 (from 3 nM to 170 nM) were globally comparable on the β-lactamases CTX-M-15 and SHV-4 with those obtained with the comparators (clavulanate, tazobactam, and sulbactam) but were far lower on TEM-1, KPC-2, P99, and AmpC than those of the comparators. In-depth studies on TEM-1 and P99 demonstrated that NXL104 had a comparable or better affinity and inactivation rate than clavulanate and tazobactam and in all cases an improved stability of the covalent enzyme/inhibitor complex.
In Vivo
Selection of a Missense Mutation in
adeR
and Conversion of the Novel
bla
OXA-164
Gene into
bla
OXA-58
in Carbapenem-Resistant
Acinetobacter baumannii
Isolates from a Hospitalized Patient
Authors: Higgins Paul G. , Schneiders Thamarai , Hamprecht Axel , Seifert Harald
Published: October 2010

The mechanism of stepwise acquired multidrug resistance in
Acinetobacter baumannii
isolates from a hospitalized patient was investigated. Thirteen consecutive multidrug-resistant isolates were recovered from the same patient over a 2-month period. The Vitek 2 system identified the isolates as meropenem-sensitive
Acinetobacter lwoffii
; however, molecular identification showed that the isolates were
A. baumannii
. Etest revealed that the isolates were meropenem resistant. The presence of oxacillinase (OXA)-type enzymes were investigated by sequencing. The clonal relatedness of isolates was assessed by pulsed-field gel electrophoresis (PFGE). Expression of the genes encoding the efflux pumps AdeB and AdeJ was performed by semiquantitative real-time reverse transcription-PCR (qRT-PCR). The
adeRS
two-component system was sequenced. All isolates had identical PFGE fingerprints, suggesting clonal identity. The first six isolates were positive for the novel
bla
OXA-164
gene. The following seven isolates, recovered after treatment with a combination of meropenem, amikacin, ciprofloxacin, and co-trimoxazole showed an increase of >7-fold in
adeB
mRNA transcripts and a missense mutation in
bla
OXA-164
, converting it to
bla
OXA-58
. Sequencing revealed a novel mutation in
adeR
. These data illustrate how
A. baumannii
can adapt during antimicrobial therapy, leading to increased antimicrobial resistance.
Rv1218c, an ABC Transporter of
Mycobacterium tuberculosis
with Implications in Drug Discovery
Authors: Balganesh Meenakshi , Kuruppath Sanjana , Marcel Nimi , Sharma Sreevalli , Nair Anju , Sharma Umender
Published: October 2010

Efflux systems are important in determining the efficacy of antibiotics used in the treatment of bacterial infections. In the last decade much attention has been paid to studying the efflux pumps of mycobacteria. New classes of compounds are under investigation for development into potential candidate drugs for the treatment of tuberculosis. Quite often, these have poor bactericidal activities but exhibit excellent target (biochemical) inhibition. Microarray studies conducted in our laboratories for deciphering the mode of action of experimental drugs revealed the presence of putative ABC transporters. Among these transporters, Rv1218c was chosen for studying its physiological relevance in mediating efflux in
Mycobacterium tuberculosis
. A Δ
Rv1218c
mutant of
M. tuberculosis
displayed a 4- to 8-fold increase in the inhibitory and bactericidal potency for different classes of compounds. The MICs and MBCs were reversed to wild-type values when the full-length
Rv1218c
gene was reintroduced into the Δ
Rv1218c
mutant on a multicopy plasmid. Most of the compound classes had significantly better bactericidal activity in the Δ
Rv1218c
mutant than in the wild-type H37Rv, suggesting the involvement of
Rv1218c
gene product in effluxing these compounds from
M. tuberculosis
. The implication of these findings on tuberculosis drug discovery is discussed.