bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Dynamic Stall on SWECS
Authors: Noll R. B. , Ham N. D.
Published: January 2010

A study of dynamic stall is presented in order to define its influence on the airfoil force and moment coefficients so that these effects can be included in the calculation of small wind energy conversion system (SWECS) loads and responses. A review of past work indicates that semiempirical methods are best suited to SWECS requirements. A definition of a dynamic stall theory is made for use in SWECS design, and the theory is implemented in SWECS loads and dynamic response analyses. Sample calculations are made for a representative vertical-axis machine. It is shown that loads and moments on the blades may be underestimated if dynamic stall is not considered.
Room Temperature Molten Salt Electrolytes for Photoelectrochemical Applications
Authors: Rajeshwar K. , Singh P. , DuBow J.
Published: January 2010

Mixtures of aluminum chloride (AlCl3) with triethylammonium chloride (Et3NHCl), 1,6-ethyl lutidinium bromide (EtluBr), tert-butyl pyridinium bromide (BPBr), and dialkyl imidazolium chloride (R2ImCl), in certain molar ratios yielded ionic liquids at room temperature which were studied with respect to their applicability as electrolytes in photoelectrochemical (PEC) cells. Background voltammograms were obtained for these electrolytes on carbon and n-GaAs electrodes. The anodic stability limit was found to be enhanced on n-GaAs relative to carbon in all cases. The cathodic decomposition potential of the electrolyte showed a smaller positive shift on n-GaAs with the exception of the 3:1 AlCl3-BPBr electrolyte. The difference in electrolyte stability behavior on carbon and n-GaAs is interpreted in terms of carrier density effects. Cyclic voltammograms were compared on carbon in the various electrolytes for a model redox system comprising the ferrocene/ferricenium couple. The separation of the cathodic and anodic waves in all the cases was consistent with a quasi-reversible redox behavior—the most sluggish electron transfer being observed in the case of the 3:1 AlCl3-BpBr electrolyte. These results are compared with those obtained previously on the AlCl3-butyl pyridinium chloride (BPC) system. Capacitance-voltage measurements were made on n-GaAs electrodes in contact with the various electrolytes. Flatband-potentials (Vfb) were deduced from these data using Mott-Schottky plots. The relative positions of the n-GaAs band-edges and the redox levels were mapped on a common potential scale utilizing these data. The ferrocene/ferricenium redox level was placed negative of the conduction band-edge in n-GaAs in all the cases. The implications of this result for PEC applications and the role of specific ion adsorption of electrolyte species on the electrostatic aspects of the n-GaAs/molten salt electrolyte interface are discussed with the aid of energy band diagrams.
The Solar Transmittance of Some Convection Suppression Devices for Solar Energy Applications: An Experimental Study
Authors: Symons J. G.
Published: January 2010

The solar transmittance of seven convection suppression devices (CDSs) has been measured as a function of both angle of incidence and azimuth angle using a large integrating sphere test facility. The CSD designs tested include a honeycomb and various slat geometries made from FEP Teflon1 film, and a tubular glass honeycomb. All FEP Teflon CSDs tested had solar transmittances not less than 0.94 for angles of incidence up to 45 deg, whereas for the glass tubular CSD, the solar transmittance was not less than 0.87 over the same range. The results for FEP Teflon CSDs compare well with previous theoretical and experimental studies of similar CSDs. Empirical solar transmittance correlation equations have been derived, based on a simple CSD solar transmittance model, and they match the measured performance of the CSDs to within 2 percent. The transmittance, reflectance, and absorptance of each CSD to isotropic diffuse radiation have been determined. The radiation properties data presented provides extensive information on some alternative CSD designs, some of which have not been analysed previously.
Integrated Solar Energy System Optimization
Authors: Young S. K.
Published: January 2010

The widespread utilization of solar energy entails the design of integrated energy systems incorporating both solar and conventional technologies. This paper presents a general methodology which uses linear programming techniques to optimize the subsystem sizing, performance, and economics of integrated energy systems.
Simplified Calculational Procedure for Determining the Amount of Intercepted Sunlight in an Imaging Solar Concentrator
Authors: Pettit R. B. , Vittitoe C. N. , Biggs F.
Published: January 2010

In imaging solar concentrators, the solar radiation incident on a receiver surface depends upon both the overall concentrator shape and the angular distribution of light rays (sunshape) that reach the receiver. Calculation of the amount of sunlight incident on the receiver usually requires sophisticated computer programs. A simplified calculational procedure is presented to solve this problem for both one and two-dimensional concentrators, with the results presented in graphical form. The procedure first determines the amount of sunshape broadening resulting from optical scattering caused by reflector or glazing materials, surface slope errors, or other “mechanical” factors such as tracking errors or vibrations. These optical effects are combined into an effective error cone which is convoluted with measured sunshapes in order to obtain effective, broadened sunshapes. Broadened sunshapes for a variety of effective error-cone distributions are calculated and presented. It is found that when the root-mean-square (RMS) width of the effective error cone is greater than approximately two times the RMS width of the incident sunshape, the broadened sunshape can be adequately described by a circular normal distribution. A specific example is included which illustrates the calculational procedure discussed in the paper.
Buffer Thermal Energy Storage for a Solar Brayton Engine
Authors: Strumpf H. J. , Barr K. P.
Published: January 2010

A study has been completed on the application of latent-heat buffer thermal energy storage to a point-focusing solar receiver equipped with an air Brayton engine. To aid in the study, a computer program was written for complete transient/steady-state Brayton cycle performance. The results indicated that thermal storage can afford a significant decrease in the number of engine shutdowns as compared to operating without thermal storage. However, the number of shutdowns does not continuously decrease as the storage material weight increases. In fact, there appears to be an optimum weight for minimizing the number of shutdowns.
Verification of BLAST by Comparison With Measurements of a Solar-Dominated Test Cell and a Thermally Massive Building
Authors: Bauman F. , Andersson B. , Carroll W. L. , Kammerud R. , Friedman N. E.
Published: January 2010

As part of an ongoing effort to use empirical data to test the computational accuracy of the building energy analysis computer program BLAST, two verification studies are reported. In the first, comparisons between air temperatures measured in a highly solar driven test cell and temperatures predicted by the program have been made. The comparisons were performed for two time periods. The simulations were driven by weather data collected at the experimental site in Los Alamos, New Mexico. The test cell configuration and weather data manipulations are described; quantitative evaluations of the comparisons between measured and predicted interior temperatures are presented; limitations of the comparisons are discussed; and sensitivities of the simulation results to uncertainties in the measured parameters are examined. In the second study, comparisons of BLAST predictions to air and surface temperatures, surface heat fluxes, and cooling loads measured in a massive structure have been carried out. These tests represent a verification of the program’s ability to (i) calculate full-scale building loads and (ii) model effects of auxiliary cooling. The structure, its controlled external environment, and the tests conducted are described; the comparisons are presented; and possible sources of discrepancies observed in the comparisons are identified and examined in detail.
Comparison of Test Results for Flat-Plate, Transpired Flat-Plate, Corrugated, and Transpired Corrugated Solar Air Heaters
Authors: Rhee S. J. , Edwards D. K.
Published: January 2010

Five selective-black-metal-plate experimental air heaters with and without transpiration were designed, fabricated, and tested to compare their technical merits. All were 61 cm × 61 cm (2ft × 2ft), double-glazed with low-iron glass, and those with transpiration contained an additional Teflon film to form a plenum above the absorber plate. The configurations were (i) a reference collector with flow on back only, (iia) a transpired slotted plate, (iib) a transpired micro-perforated plate, (iii) a corrugated plate with flow on back, and (iv) a transpired slotted corrugated plate. The results show the magnitude of technical improvement that can be obtained through the slotting, perforating, and corrugating strategems.
The Thermal Performance of the Two-Pass, Two-Glass-Cover Solar Air Heater
Authors: Persad P. , Satcunanathan S.
Published: January 2010

Analytic models are developed for the performance prediction of a two-glass-cover solar air heater operated in both the single-pass and two-pass modes. It is shown that the two-pass mode of operation is superior to the single-pass mode of operation over the range of collector inlet temperatures considered. This is seen to be mainly due to the fact that, in the two-pass mode of operation, the outer glass cover is cooled by the working fluid, thereby reducing the top losses. It is also shown that the performance in the two-pass mode of operation is independent of length, over the range of collector lengths considered, and that a critical plate spacing, dependent on the temperature level of operation of the collector, is indicated. Predicted values of performance are in good agreement with experimental results.
Simulation of a Solar Pond With a Stratified Storage Zone
Authors: Newell T. A.
Published: January 2010

Numerical simulation results are presented which compare performances between a conventional solar pond and a proposed solar pond configuration. The proposed pond maintains a stratified storage zone below the lower convecting zone of a pond. Addition of a stratified storage zone is shown to have two general results. First, ground losses are minimized, and second, higher process temperature levels can be accommodated. Additionally, the proposed configuration may result in a reduction of pond investment cost.
In Situ Measurement of Solar Pond Density Profiles
Authors: Langeliers J. , Stojanoff C. G.
Published: January 2010

The stability of a solar pond is critically dependent upon the maintenance of a suitable vertical density gradient, but rapid, inexpensive methods of profiling the density gradient do not presently exist. A method for obtaining in situ density profiles through measurement of hydrostatic pressure differential is described and investigated. Design parameters and experimental results are presented for a prototype instrument.
Oldham-Coupling Second-Harmonic Balancer
Authors: Tsai Lung-Wen
Published: January 2010

This paper describes a mechanical balancer, based on the Oldham-type shaft coupling, for reducing or eliminating second-harmonic out-of-balance in mechanical systems. It is shown that by proper arrangement of two Oldham couplings, a balancer can be obtained for the elimination of second-harmonic shaking forces or second-harmonic shaking moments or a combination of both shaking forces and moments. The advantage of this balancer is that it runs at the primary speed of the machine to be balanced whereas the Lanchester-type balancer must run at two times the primary speed to achieve the same balancing effect. It is also shown that the addition of eccentric masses on the input and / or output shafts of the balancer couplings will permit first- and second-harmonic out-of-balance to be eliminated simultaneously. A prototype balancer has been tested to verify the concept.
On the Analysis and Synthesis of the Workspace of a Three-Link, Turning-Pair Connected Robot Arm
Authors: Freudenstein F. , Primrose E. J. F.
Published: January 2010

The workspace of a three-axis, turning-pair connected robot arm of general proportions has been analyzed in terms of the volume swept out by the surface of a skew torus rotating about an offset axis in space. The algebraic geometry of this configuration has been utilized in the determination of workspace characteristics. Algebraic criteria have been derived for extreme axial and radial reach and the elimination of two types of voids which were found to be characteristic of the 3-R robot configuration. These criteria can be used both in the analysis and synthesis stages of robot design.
Method for Generation of Spiral Bevel Gears With Conjugate Gear Tooth Surfaces
Authors: Litvin F. L. , Tsung Wei-Jiung , Coy J. J. , Heine C.
Published: January 2010

The authors proposed a method for generation of spiral bevel gears that provides conjugate gear tooth surfaces. This method is based on a new principle for the performance of parallel motion of a straight line that slides along two mating ellispses with related dimensions and parameters of orientation. The parallel motion of the straight line, that is the contact normal, is performed parallel to the line which passes through the foci of symmetry of the related ellipses. The manufacturing of gears can be performed with the existing Gleason’s equipment.
A Three-Fingered Pantograph Manipulator—A Kinematic Study
Authors: Hunt K. H. , Torfason L. E.
Published: January 2010

General kinematic principles are set down for an algorithmically-simple three-fingered robot-attachment intended to grasp and manipulate objects. After proposing a design for a finger-tip that determines precisely a grasping-point, the geometry of a swivelling pantograph-arrangement is pursued in some detail. Forward and inverse relations are developed, and a means for maintaining grasp during manipulation is outlined. Force-sensing and driving-means are touched upon. Certain alternative schematic designs are presented and compared.
Characteristic Surfaces for Three-Position Motion Generation With Planar Four-Bar Mechanisms
Authors: Barker C. R. , Baumann J.
Published: January 2010

This paper considers the relationship between the three-position motion generation problem and the solution space for planar four-bar mechanisms. After one half of the basic four bar had been selected, two infinities of solutions still remained. These solutions are mapped in a plane to determine where the particular types of mechanisms occur. A contour is then generated in the mapping plane which joins together all solutions which share a common characteristic in regard to their link lengths. This same contour can be displayed in the solution space and in the Cartesian plane in which the motion generation is defined. Significant useful information to assist in selecting the final solution is obtained. A numerical example is used for illustration, but the results can be applied to any three-position motion generation problem.
An Investigation of Pshenichnyi’s Recursive Quadratic Programming Method for Engineering Optimization
Authors: Gabriele G. A. , Beltracchi T. J.
Published: January 2010

This paper discusses Pshenichnyi’s recursive quadratic programming algorithm for use in engineering optimization problems. An evaluation of the original algorithm is offered and several modifications are presented. The modifications include; addition of a variable metric update of the Hessian, an improved active set criterion, direct inclusion of the variable bounds, a divergence control mechanism, and updating schemes for the algorithm parameters. Implementations of the original algorithm and the modified algorithm were tested against the Sandgren test set of 23 engineering optimization problems. The results indicate that the modified algorithm was able to solve 20 of the 23 test problems while the original algorithm solved only 11. The modified algorithm was more efficient than the original on all the test problems.
On the Equations of Motion for Robot Arms and Open Kinematic Chains
Authors: Gupta S. , Townsend M. A.
Published: January 2010

The closed-form equations of motion for robot arms and other open kinematic chains are derived using the Newton-Euler equations in a form particularly suitable for the automatic modeling and on-line control of such mechanisms. The approach is based on Vukobratovic’s method [3], using more conventional Western notation.
Development of a Hybrid SQP-GRG Algorithm for Constrained Nonlinear Programming
Authors: Parkinson A. , Wilson M.
Published: January 2010

The optimization of many engineering design problems requires a nonlinear programming algorithm that is robust, efficient, and feasible at intermediate iterations. Based on the strengths of the generalized reduced gradient (GRG) and sequential quadratic programming (SQP) algorithms, a hybrid SQP-GRG algorithm is developed. The hybrid algorithm uses the SQP search direction and a modified GRG line search. The resulting SQP-GRG algorithm is shown to be robust, feasible at intermediate iterations, and comparable in efficiency to Powell’s SQP algorithm on 26 test problems.
Crowned Spur Gears: Methods for Generation and Tooth Contact Analysis—Part I: Basic Concepts, Generation of the Pinion Tooth Surface by a Plane
Authors: Litvin F. L. , Zhang J. , Handschuh R. F.
Published: January 2010

A topology of crowned spur pinion tooth surface that reduces the level of transmission errors due to misalignment is proposed. The geometry of the deviated pinion tooth surface and regular gear tooth surface, along with tooth contact analysis is discussed. Generation of the deviated pinion tooth surface by a plane whose motion is controlled by a five-degree-of-freedom system is proposed. Numerical results are included and indicate that transmission errors remain low as the gears are misaligned.
An Experimental Investigation of OC-OTEC Direct-Contact Condensation and Evaporation Processes
Authors: Sam R. G. , Patel B. R.
Published: January 2010

Heat transfer data are presented for direct-contact evaporator and condenser geometries suitable for Open-Cycle Ocean Thermal Energy Conversion (OC-OTEC) applications. Falling turbulent jets and films were tested at typical operating conditions. The flash evaporator performance was relatively constant over the range of conditions tested, with efficiencies as high as 95 percent due to the breakup of the jets (or films) into sprays. The condenser performance was only affected by the jet or film Reynolds number and the steam air content. Condenser heat transfer coefficients of the order of 27 kW/m2 °C were achieved with jets which were higher than those obtained with films. An empirical correlation was developed for the condenser data after it was shown that none of the existing correlations found in the literature could correlate all of the data trends observed.
Thermal Analysis of a Solar Advanced Water/Steam Receiver
Authors: Yeh L. T. , Wiener M.
Published: January 2010

The Department of Energy and Sandia Laboratories have sponsored the development of a conceptual design for a 100-MWe solar advanced water/steam receiver that is cost-effective and will perform within a practical and reliable power generation system. The design requirements and the basic features of receiver are described. This paper presents the methods used to estimate the receiver’s thermal efficiency and predict its thermal hydraulic performance. The receiver under consideration is external with screen tubes using a forced recirculation system. Thermal efficiency of the receiver at the design point is estimated at 89.2 percent. Effects due to changing ambient conditions, such as ambient temperature and windspeed, and changes of solar incident power are also presented.
Air Infiltration and Building Tightness Measurements in Passive Solar Residences
Authors: Persily A. K. , Grot R. A.
Published: January 2010

The airtightness of about fifty passive solar homes located throughout the United States was studied using low-cost measurement techniques. These homes are part of the DOE-sponsored Class B monitoring program conducted at the Solar Energy Research Institute (SERI) to evaluate the thermal performance of passive solar residential buildings. These tests provide the first set of building tightness measurements on a large group of passive solar buildings. The measurements include pressurization tests to measure airtightness and tracer gas measurements to determine air infiltration rates. The pressure tests show a variation in the air-tightness of these homes from 3 to 30 exchanges/hr at 50 Pascal, with a median of 9.5 exchanges/hr. The air infiltration measurements cover a wider range from 0.05 to 3.0 exchanges/hr, with a median of 0.5 exchanges/hr. In comparing the tightness of these homes to other U.S. homes, one finds that these passive solar homes are not significantly tighter than homes built with less of an emphasis on energy use.
Open-Cycle Desiccant Air Conditioning as an Alternative to Vapor Compression Cooling in Residential Applications
Authors: Jurinak J. J. , Mitchell J. W. , Beckman W. A.
Published: January 2010

The performance of open-cycle desiccant air conditioners for residential applications is evaluated. The performance of these systems is compared to that of vapor compression air conditioners on the basis of primary energy use and cost. Systems with improved dehumidifiers can achieve seasonal COP’s on the order of 1.1. These systems, when coupled with a solar energy system to supply regeneration energy, are significantly better than conventional air conditioners on a primary energy basis, but are not presently cost-competitive.
Passive Solar Performance of Tech House V
Authors: Reid R. L. , McGraw B. A. , Bedinger A. F. G.
Published: January 2010

The performance of a passive solar modular house located in Knoxville, Tennessee (TECH House V) was determined for the 1981–1982 heating season. The 111 m2 (1200 ft2) house has 13.7 m2 (144 ft2) of south facing glass and 20 vertical water tubes. The auxiliary heat was measured directly while the net solar gain was calculated using hourly measured vertical insolation, weather, and inside-space temperature data. The solar collection efficiency was 64 percent and the solar fraction was 0.40.
Studies of Biomass Yield From a Near-Shore Macroalgal Test Farm
Authors: Neushul M. , Harger B. W. W.
Published: January 2010

This paper reports the results of studies in 1981 and 1982 of marine biomass yield from a near-shore, 0.48 hectare test farm at Ellwood, California. The experimental planting was made to ascertain whether or not the plants would maintain a high yield after repeated cutting, and to see what effect planting density has on yield. The test farm was planted with 722 plants and operated in all seasons of the year. Quarterly harvests were made from plants planted at densities of one plant per m2, one plant per 4 m2 and one plant per 16 m2. Eleven metric tons of biomass were planted initially on a sandy sea floor. This produced a total of 50 wet metric tons of harvested biomass in 12 months.
Heat Transfer Analysis in Environmental Control Using an Underground Air Tunnel
Authors: Goswami D. Y. , Dhaliwal A. S.
Published: January 2010

This paper presents heat transfer analysis of a passive summer cooling and winter preheating technique, which utilizes the underground temperature at a depth of 6 ft (1.83m) or more. In this study, a computer model solution has been developed for predicting the air temperature at any point, at any time while passing through the underground pipe. The air temperature is a function of the inlet air temperature and humidity, soil temperature, soil properties, the pipe (length, diameter, shape, and material), and the air flow velocity. Experiments were performed to measure air temperature, soil temperature, and pipe surface temperature at different lengths and different intervals of times. The results of the experiments are compared with theoretical calculations, which showed very good agreement. Thus the theoretical model may be used for predicting the performance of such systems in the future.
Effect of Variable Nusselt Number and Nonuniform Wall Irradiation on Collector Performance
Authors: Wijeysundera N. E.
Published: January 2010

This paper describes an analytical study of the laminar heat transfer in cylindrical, flat and fin-tube absorber ducts subjected to variable wall irradiation and external heat losses. The study addresses two collector design aspects. The first is the effect of the wall thermal boundary condition on the collector efficiency factors. The second aspect is the efficiency improvement which can be achieved by redistributing the incident radiation in a nonuniform manner. Analysis shows that the use of the average Nusselt numbers for the constant wall temperature boundary condition in a radially lumped solution give results for the efficiency factors which agree within about 6 percent with the distributed solution. The efficiency improvement which may be achieved by using stepwise increases in radiation with conventional absorbers is less than about 8 percent. The solution procedure developed in this study can be extended to study other flow regimes when the constant wall temperature solution is known.
Enhancement of Spray Flash Evaporation by Means of the Injection of Bubble Nuclei
Authors: Miyatake O. , Tomimura T. , Ide Y.
Published: January 2010

Spray flash evaporators are being used or considered for power systems utilizing solar energy, ocean thermal energy, and geothermal energy. As part of an attempt to develop a compact, efficient flash evaporator, an experimental study of the effect of injection of bubble nuclei has been conducted. The bubble nuclei were generated by electrolyzing warm water, which was ejected from a simple tubular nozzle into a low-pressure vapor zone. Effects of electrolytic current level, nozzle diameter, liquid flow rate, liquid temperature, and superheat were investigated. The evaporator rates attained were superior to those in conventional multistage flash evaporators with open channels.
Air Molten Salt Direct-Contact Heat Exchange
Authors: Bohn M. S.
Published: January 2010

Volumetric heat transfer coefficients for direct-contact heat exchange between air and molten nitrate salt have been measured as a function of air and salt flow rates at 350° C salt inlet temperature. Using these heat transfer data for a packed column-type heat exchanger, an economic analysis was used to compare direct-contact heat exchange with conventional finned-tube heat exchangers. High volumetric rates of heat transfer (2000–3000 W/m3 °C) and flexibility in choice of materials of construction allow one to realize significant economic benefits by using direct-contact heat exchange in this application.
Experimental and Theoretical Analysis of a Solar Liquid Piston Pump
Authors: Murphy C. L. , Brew-Hammond A.
Published: January 2010

The Solar Liquid Piston Pump (SLPP) is driven by oscillations of an enclosed column of liquid Freon 113. Cyclic evaporation and condensation from heating and cooling coils at the top of the liquid column generate the oscillations. The frequency and amplitude of the oscillations are enhanced by momentum forces in the inlet, outlet, and working tubes. Three geometrically different experimental models of a SLPP have been tested. To optimize the performance of the SLPP, a theoretical model was required to account for the large number of interdependent parametres that could be varied. A semiemperical time-incremented computer model was developed. A theoretical cycle was assumed and the heat transfer and fluid friction coefficient adjusted, within reasonable limits, so that the theoretical pressure-volume diagrams agreed closely with experimental ones. Input parameters were then varied for the theoretical model and compared to experimental results available. The theoretical model successfully predicted performance trends of the SLPP.
A Computer Model for Stress Analysis of Spherically Curved Solar Panels
Authors: Vallabhan C. V. Girija , Selvam R. Panneer
Published: January 2010

Spherically curved solar reflectors consist of a thin glass plate elastically bent to form a spherical surface, glued onto a honeycomb backing, and covered with steel plates at the back and with plastic strips on the sides. Nonlinear Von Karman plate equations are used to analyze the induced stresses in the glass plate as its deflections become large. The analysis consists of evaluation of stresses due to bending and membrane forces during the forming of the spherical surface, along with the calculation of edge moments and the transverse loads due to molds. The interaction of the plate with the honeycomb is analyzed assuming that the plate is resting on an elastic foundation (honeycomb), where the edge moments and the transverse forces calculated earlier are released. The results are compared with other available solutions as well as experimental data.
Example of Second-Law Efficiency of Solar-Thermal Cavity Receivers
Authors: Moynihan P. I.
Published: January 2010

Properly quantified performance of a solar-thermal cavity receiver must not only account for the energy gains and losses as dictated by the First Law of thermodynamics, but it must also account for the quality of that energy. Energy quality can only be determined from the Second Law. In this paper, an equation developed for the Second-Law efficiency of a cavity receiver is presented as an evolution from the definition of available energy or “availability” (occasionally called exergy). The variables required are all either known or readily determined. The importance of considering the Second-Law is emphasized by a comparison of the First- and Second-Law efficiencies around an example of data collected from two receivers that were designed for different purposes, where the attempt was made to demonstrate that a Second-Law approach to quantifying the performance of a solar-thermal cavity receiver lends more complete insight than does the conventional solely applied First-Law approach.
Transfer of a Metal From a Transparent Film to the Surface of Silicon to Produce P-N Junction Solar Cells
Authors: Toulemonde M. , Muller J. C. , Stuck B.
Published: January 2010

A new method is proposed for preparing silicon P-N junctions. The first consists in fixing a transparent plastic film coated with a thin layer of a conventional dopant on the surface of the wafer, then illuminating this sandwich with a higher power Q switched laser. Two successive pulses are used, the first being able to transfer the dopant from the film to the silicon surface, the second to induce a liquid phase diffusion incorporating the dopant into the silicon lattice. Solar cells have been prepared by using this process, implying several attractive features.
A Simple Device for Measuring Fouling in a Heat Exchanger Tube
Authors: Owens W. L.
Published: January 2010

A simple, electric-heating-tape-wrapped and insulated tube device has been developed by Lockheed Ocean Systems (LMSC) to monitor the thermal resistance of fouling (RF) from seawater inside a simulated ocean thermal energy conversion (OTEC) heat exchanger tube. It is compared with another directly-heated monitor that has been used by others in many biofouling measurement programs and with an indirect method in which a secondary fluid would be electrically heated. An analysis of experimental uncertainty in RF determination is presented for the LMSC and indirect methods. Representative RF data for aluminum and copper-nickel LMSC devices are presented. The three methods are compared subjectively with respect to ten cost, use, and performance criteria, and the LMSC device has a first-place ranking for seven of the criteria.
Photovoltaic-Electrolyzer System Transient Simulation Results
Authors: Leigh R. W. , Metz P. D. , Michalek K.
Published: January 2010

Brookhaven National Laboratory has developed a Hydrogen Technology Evaluation Center to illustrate advanced hydrogen technology. The first phase of this effort investigated the use of solar energy to produce hydrogen from water via photovoltaic-powered electrolysis. A coordinated program of system testing, computer simulation, and economic analysis has been adopted to characterize and optimize the photovoltaic-electrolyzer system. This paper presents the initial transient simulation results. Innovative features of the modeling include the use of real weather data, detailed hourly modeling of the thermal characteristics of the PV array and of system control strategies, and examination of systems over a wide range of power and voltage ratings. The transient simulation system TRNSYS was used, incorporating existing, modified or new component subroutines as required. For directly coupled systems, we found the PV array voltage which maximizes hydrogen production to be quite near the nominal electrolyzer voltage for a wide range of PV array powers. The array voltage which maximizes excess electricity production is slightly higher. The use of an ideal (100 percent efficient) maximum power tracking system provides only a six percent increase in annual hydrogen production. An examination of the effect of PV array tilt indicates, as expected, that annual hydrogen production is insensitive to tilt angle within ± 20 deg of latitude. Summer production greatly exceeds winter generation. Tilting the array, even to 90 deg, produces no significant increase in winter hydrogen production.
Operation of a 25 kWh Barium Hydroxide Latent Heat Storage Unit in the Power Range 2–6 kW
Authors: Krause S. , Tamme R.
Published: January 2010

Among the latent heat storage media considered for short-term storage of solar and nonsolar heat in house heating and process heat applications, barium hydroxide is particularly promising because of its large storage density and its storage temperature of 78 °C. Results of tests with a 25 kWh barium hydroxide “dynamic” latent heat storage unit are reported. The investigations included the discharge behavior, the range of possible discharge powers, variations of the power during discharges, and the “useful” temperature for a future applier. The results are encouraging. The medium remained unchanged during 40 charge/discharge cycles performed within ten months. Storage densities up to 125 kWh/m3 were achieved with a potential for still higher ones.
Stretched-Membrane Heliostat Technology
Authors: Murphy L. M.
Published: January 2010

The stretched-membrane concept is a potentially low-cost and structurally efficient method of attaining and supporting a large, optically accurate surface for heliostat applications. In this concept, a high-strength structural film coated with a highly reflective surface is stretched uniformly on a torroidal frame. Prior and current research, directed at allowing the full potential of this novel concept to be realized, is described. Technical issues and results described include membrane attachment approaches, focusing, and the numerous structural response mechanisms specific to this concept.
Latent Thermal Storage Unit Using Form-Stable High Density Polyethylene; Part II: Numerical Analysis of Heat Transfer
Authors: Kamimoto M. , Abe Y. , Kanari K. , Takahashi Y. , Tani T. , Ozawa T.
Published: January 2010

Heat transfer in the latent thermal storage unit using form-stable high density polyethylene rods has been numerically analyzed. The analysis is based on simple explicit one-dimensional finite difference equations. The calculation can well simulate both the charge and discharge characteristics of the prototype storage unit developed by the present authors. The computer simulation has been used also to speculate the performance of the storage unit under various conditions. Effects of several parameters on the discharge characteristics have been quantitatively made clear.
CRISPR/Cas, the Immune System of Bacteria and Archaea
Authors: Horvath Philippe , Barrangou Rodolphe
Published: January 2010

CRISPR Defenses

Prokaryotes can be infected by parasites and pathogens and, like eukaryotes, have evolved systems to protect themselves.
Horvath and Barrangou
(p.
167
) review a recently discovered prokaryotic “immune system” characterized by CRISPR—clustered regularly interspaced short palindromic repeats—found in most archaeal and many bacterial species. CRISPR loci harbor short sequences captured from viruses and invasive genetic elements. These sequences are transcribed, and the RNA is cleaved into short CRISPR RNAs (crRNAs) by one of a family of CRISPR-associated (cas) proteins. These crRNAs direct other cas family proteins to homologous nucleic acid targets to effect their destruction. Through its ability to impede the spread of specific nucleic acid sequences, the CRISPR/Cas systems might be exploited to block the dissemination of antibiotic-resistance markers.
E-Type Asteroid (2867) Steins as Imaged by OSIRIS on Board Rosetta
Authors: Keller H. U. , Barbieri C. , Koschny D. , Lamy P. , Rickman H. , Rodrigo R. , Sierks H. , A’Hearn M. F. , Angrilli F. , Barucci M. A. , Bertaux J.-L. , Cremonese G. , Da Deppo V. , Davidsson B. , De Cecco M. , Debei S. , Fornasier S. , Fulle M. , Groussin O. , Gutierrez P. J. , Hviid S. F. , Ip W.-H. , Jorda L. , Knollenberg J. , Kramm J. R. , Kührt E. , Küppers M. , Lara L.-M. , Lazzarin M. , Moreno J. Lopez , Marzari F. , Michalik H. , Naletto G. , Sabau L. , Thomas N. , Wenzel K.-P. , Bertini I. , Besse S. , Ferri F. , Kaasalainen M. , Lowry S. , Marchi S. , Mottola S. , Sabolo W. , Schröder S. E. , Spjuth S. , Vernazza P.
Published: January 2010

Smooth Space Pebble

In September 2008, on its way to meet comet 67P/Churyumov-Gerasimenko, the Rosetta spacecraft flew by asteroid Steins, a member of a very rare class of asteroids that had never been observed closely by spacecraft.

Keller
et al.

(p.
190
) analyzed the images to generate a reconstruction of the asteroid's shape. Steins is oblate with an effective spherical diameter of 5.3 kilometers, and it lacks small craters, which may have been erased by surface reshaping. Indeed, Steins's shape resembles that of a body that was spun-up by the YORP effect—a torque produced by incident sunlight, which can alter the rotation rate of a small body—that causes material to slide toward the equator. This effect may have produced Steins's distinctive diamond-like shape.
Nematic Electronic Structure in the “Parent” State of the Iron-Based Superconductor Ca(Fe
1–

x

Co

x

)
2
As
2
Authors: Chuang T.-M. , Allan M. P. , Lee Jinho , Xie Yang , Ni Ni , Bud’ko S. L. , Boebinger G. S. , Canfield P. C. , Davis J. C.
Published: January 2010

Nematic Electronic Order in Iron Superconductors

The properties of many high-temperature superconductors vary strongly as the composition of a doping element changes, and at sufficient under- or overdoping, other phases with different types of electronic ordering can form. Chuang et al. (p.
181
; see the Perspective by
Fradkin and Kivelson
) use scanning tunneling microscopy techniques to probe the electronic structure of an underdoped compound in the iron superconductor family, Ca(Fe

1−
x

Co

x

)
2
As
2
. They observed periodic nanostructures oriented along Fe–Fe bonds that exhibit an electronic ordering related to ordering seen in nematic liquid crystals.
Deep Mantle Properties
Authors: Hirose Kei
Published: January 2010

High-temperature, high-pressure measurements combined with observation and calculations are providing a better picture of Earth's lower mantle.
Virtual Archaeologists Recreate Parts of Ancient Worlds
Authors: Bawaya Michael
Published: January 2010

Using techniques borrowed from the entertainment industry, more and more archaeologists are boosting their imaginations and insights with virtual worlds.
Use of the Normalized Absorbance Ratio as an Internal Standardization Approach To Minimize Measurement Error in Enzyme-Linked Immunosorbent Assays for Diagnosis of Human Papillomavirus Infection
Authors: Ramanakumar Agnihotram V. , Thomann Patricia , Candeias Joao M. , Ferreira Silvaneide , Villa Luisa L. , Franco Eduardo L.
Published: January 2010

The serological detection of antibodies against human papillomavirus (HPV) antigens is a useful tool to determine exposure to genital HPV infection and in predicting the risk of infection persistence and associated lesions. Enzyme-linked immunosorbent assays (ELISAs) are commonly used for seroepidemiological studies of HPV infection but are not standardized. Intra- and interassay performance variation is difficult to control, especially in cohort studies that require the testing of specimens over extended periods. We propose the use of normalized absorbance ratios (NARs) as a standardization procedure to control for such variations and minimize measurement error. We compared NAR and ELISA optical density (OD) values for the strength of the correlation between serological results for paired visits 4 months apart and HPV-16 DNA positivity in cervical specimens from a cohort investigation of 2,048 women tested with an ELISA using HPV-16 virus-like particles. NARs were calculated by dividing the mean blank-subtracted (net) ODs by the equivalent values of a control serum pool included in the same plate in triplicate, using different dilutions. Stronger correlations were observed with NAR values than with net ODs at every dilution, with an overall reduction in nonexplained regression variability of 39%. Using logistic regression, the ranges of odds ratios of HPV-16 DNA positivity contrasting upper and lower quintiles at different dilutions and their averages were 4.73 to 5.47 for NARs and 2.78 to 3.28 for net ODs, with corresponding significant improvements in seroreactivity-risk trends across quintiles when NARs were used. The NAR standardization is a simple procedure to reduce measurement error in seroepidemiological studies of HPV infection.
Diversity of VacA Intermediate Region amongHelicobacter pyloriStrains from Several Regions of the World
Authors: Chung Christine , Olivares Asalia , Torres Eugenia , Yilmaz Ozlem , Cohen Henry , Perez-Perez Guillermo
Published: January 2010

Helicobacter pyloriis known to be a major cause of gastric carcinoma and peptic ulceration.cagApositivity andvacA's signal regions and mid-regions are well-characterized markers ofH. pylori's virulence. Recently, an intermediate region has been identified as another strong marker ofH. pylori-associated disease, and its i1 allele has been linked with severe diseases in colonized hosts. The goal of this study was to determine the prevalence of the intermediate alleles inH. pyloriisolates from China, Turkey, and Uruguay and from U.S. Africans and to compare their distribution with other well-characterized virulence factors. Originally, 123H. pyloristrains were studied, but 3 were excluded due to the failure to amplify the intermediate region in these samples. Therefore, a total of 120 strains were analyzed: 30 Chinese isolates, 35 Turkish isolates, 30 Uruguayan isolates, and 25 U.S. African isolates. The s type and the m type were determined by PCR amplification. The i type was identified by PCR amplification and DNA sequencing. CagA status was determined by PCR methodology. There was a strong correlation among CagA positivity, s1, and i1 in Chinese, U.S. African, and Uruguayan isolates, but less correlation among these markers in Turkish isolates. A new intermediate variant (i3) was identified in 25.7% of Turkish strains and 3.3% of the Chinese strains. In summary, the distribution of CagA positivity and s1 correlated with the i1 in the three populations, except in the Turkish population, which showed a disproportionate representation of the i3 allele. Phylogenetic mapping confirmed the i-typing method previously defined and adopted for this study. The phylogenetic tree showed country-specific correlation with the intermediate region. Our results showed that the i1 allele is strongly associated with CagA positivity and thevacAs1 allele, suggesting its role as a virulence marker and potential predictor for clinical outcome.
Performance of Fusidic Acid (CEM-102) Susceptibility Testing Reagents: Broth Microdilution, Disk Diffusion, and Etest Methods as Applied to
Staphylococcus aureus
Authors: Jones Ronald N. , Castanheira Mariana , Rhomberg Paul R. , Woosley Leah N. , Pfaller Michael A.
Published: January 2010

Fusidic acid (CEM-102) is an established antistaphylococcal agent that has been used in clinical practice for more than 4 decades. The activity of fusidic acid against 778 isolates of
Staphylococcus aureus
collected from U.S. (53.8% were methicillin-resistant
S. aureus
[MRSA]) and Canadian (46.5% were MRSA) medical centers was assessed to determine the intermethod accuracy of the Clinical and Laboratory Standards Institute (CLSI) and Etest methods. Broth microdilution MIC results were compared by scattergram analysis to zone diameters around commercially available 5- and 10-μg disks. Acceptable correlation (
r
= 0.74 to 0.76) was observed for the two disk concentrations, and applying breakpoints of ≤1 μg/ml (≥22 mm) for susceptibility (S) and ≥4 μg/ml (≤19 mm) for resistance (R) provided 99.9% absolute intermethod categorical agreement. Reference CLSI MIC versus Etest MIC results (
r
= 0.77; 728 strains) showed 55.4% identical results and agreement of 99.7% ± one log
2
dilution. The diagnostic susceptibility testing reagents (including Etest) for fusidic acid (CEM-102) performed at an excellent level of intermethod agreement for the proposed breakpoint criteria.
Highly Pathogenic H5N1 Avian Influenza Virus Induces Extracellular Ca
2+
Influx, Leading to Apoptosis in Avian Cells
Authors: Ueda Mayo , Daidoji Tomo , Du Anariwa , Yang Cheng-Song , Ibrahim Madiha S. , Ikuta Kazuyoshi , Nakaya Takaaki
Published: January 2010

In this study, we show that the highly pathogenic H5N1 avian influenza virus (AIV) (A/crow/Kyoto/53/04 and A/chicken/Egypt/CL6/07) induced apoptosis in duck embryonic fibroblasts (DEF). In contrast, apoptosis was reduced among cells infected with low-pathogenic AIVs (A/duck/HK/342/78 [H5N2], A/duck/HK/820/80 [H5N3], A/wigeon/Osaka/1/01 [H7N7], and A/turkey/Wisconsin/1/66 [H9N2]). Thus, we investigated the molecular mechanisms of apoptosis induced by H5N1-AIV infection. Caspase-dependent and -independent pathways contributed to the cytopathic effects. We further showed that, in the induction of apoptosis, the hemagglutinin of H5N1-AIV played a major role and its cleavage sequence was not critical. We also observed outer membrane permeabilization and loss of the transmembrane potential of the mitochondria of infected DEF, indicating that mitochondrial dysfunction was caused by the H5N1-AIV infection. We then analyzed Ca
2+
dynamics in the infected cells and demonstrated an increase in the concentration of Ca
2+
in the cytosol ([Ca
2+
]
i
) and mitochondria ([Ca
2+
]
m
) after H5N1-AIV infection. Regardless, gene expression important for regulating Ca
2+
efflux from the endoplasmic reticulum did not significantly change after H5N1-AIV infection. These results suggest that extracellular Ca
2+
may enter H5N1-AIV-infected cells. Indeed, EGTA, which chelates extracellular free Ca
2+
, significantly reduced the [Ca
2+
]
i
, [Ca
2+
]
m
, and apoptosis induced by H5N1-AIV infection. In conclusion, we identified a novel mechanism for influenza A virus-mediated cell death, which involved the acceleration of extracellular Ca
2+
influx, leading to mitochondrial dysfunction and apoptosis. These findings may be useful for understanding the pathogenesis of H5N1-AIV in avian species as well as the impact of Ca
2+
homeostasis on influenza A virus infection.