bluuebunny/crossref_metadata_2025 huggingface dataset:
Oscillatory Motions in the Nonconvective Layer of a Solar Pond
Authors: Almanza R. , Bryant H. C.
Published: January 2010

Temperature oscillations in the nonconvective layers of the Na Cl solar pond of the University of New Mexico have been observed. These oscillations, which appear during the day and early in the evening, are correlated with the flux of solar energy in these regions. The period varies from 90 s up to 400 s, depending on the depth, and the amplitude can be as large as 1.4°C. The phenomena observed are conjectured to overstable oscillations predicted from double diffusive convection theory.
Passive Cooling Measurements for a Concentrating Photovoltaic Array
Authors: Deaver F. K. , Edenburn M. W.
Published: January 2010

Solar cells in a concentrating photovoltaic array absorb heat that must be removed. One method is to use a finned aluminum heat exchanger whose modeling requires estimating the coefficient of heat transfer from fins to surroundings; transfer depends on such parameters as windspeed and direction, and exchanger design. A transient analytical model has been constructed and applied to experimental data. Coefficients of heat transfer were calculated and correlated with windspeed and direction, which appear to have a definite effect on the overall coefficient. The transient model and apparent relationships between windspeed and convective coefficients are described.
Testing and Analysis of a Heat-Pipe Solar Collector
Authors: Ribot J. , McConnell R. D.
Published: January 2010

We developed an integral heat-pipe/evacuated-tube solar collector in which the inner receiver tubes form the evaporator sections of glass heat pipes. This paper describes both theoretical analyses and empirical tests, comparing the performance of the glass heat-pipe solar collector with one of today’s high efficiency evacuated-tube solar collectors. The comparison demonstrates that the performance of the two collectors is effectively identical. The testing and analysis indicate that the glass-wick-type glass heat pipe is an effective heat transfer system for evacuated-tube solar collectors.
Mappings of Spatial Kinematics
Authors: Ravani B. , Roth B.
Published: January 2010

This paper studies mappings of spatial kinematics and the geometry for which a spatial displacement is an element. Study’s soma is reviewed and it is shown that Euclidean geometry in three-space with spatial displacements as elements corresponds to elliptic geometry of points in a projective dual three-space. Study’s eight parameters are used to define the mapping of spatial kinematics into points of this projective dual three-space. The basic geometric properties of this dual three-space representation of Study’s soma is developed and it is applied to the study of spatial motions and mechanisms.
Optimum Configuration for an Isotropic Rotor
Authors: Shawki G. S. A. , Metwalli S. M. , Sharobeam M. H.
Published: January 2010

This paper deals with the optimization of isotropic rotors which are equally stressed in radial and tangential directions, the merit criteria being maximum inertia per unit mass, coupled with most uniform stress distribution, these features being in turn grouped in the so-called “shape factor.” The present study sets forth a new profile for the isotropic unimaterial rotor with a shape factor value more than 0.971 in contradistinction to the practical value of 0.88 as obtained for a constant-strength disk.
A Basic Two-Stage Decomposition Strategy for Design Optimization
Authors: Johnson R. C. , Benson R. C.
Published: January 2010

A basic two-stage decomposition strategy for design optimization is described. Resolution of the independent variable vector into two parts is accompanied by a decomposition of the optimization problem equation system into a modular component and an integrating system component. The modular component must be explicitly solvable by an optimization technique, and specifically the method of optimal design is used. The integrating system component is generally the basis of control for an automated optimal design search process of reduced dimensionality. A technique is developed for handling possibilities of incompatible specifications in the modular component. Three examples illustrate application of the developed algorithm.
A Multistage Decomposition Strategy for Design Optimization
Authors: Johnson R. C. , Benson R. C.
Published: January 2010

A basic multistage decomposition strategy for design optimization is described. Resolution of the independent variable vector is accompanied by a decomposition of the optimization problem equation system into sets of modular components and an integrating system component. The optimization subproblem of each modular component set must be explicitly solvable, and specifically the method of optimal design is used. Techniques are developed for handling interactions between the modular component sets. The integrating system component is the basis of control for an automated optimal design search process of reduced dimensionality. An example illustrates application of the developed algorithm.
Analytical Reconstruction of the Running Surfaces of Gear Teeth. Part 2: Combining Tooth Spacing Measurements with Profile and Lead Measurements
Authors: Mark W. D.
Published: January 2010

Methods are developed for analytically reconstructing the absolute geometric deviations of the running surfaces of all teeth on a gear or pinion from perfect equispaced involute surfaces. Two of the methods utilize a rectangular array of tooth spacing deviation point measurements optimally located at the zeros of Legendre polynomials in the axial and radial directions where profile and lead deviation measurements are assumed to have been made. Each of these two methods utilizes the multiple tooth spacing deviation measurements to determine the absolute spacing deviations of the mean planes of the deviations of the tooth running surfaces determined from profile and lead measurements. A convergent two-dimensional Legendre polynomial representation of tooth surface deviations that interpolates between point measurements of tooth surface deviations located in rectangular arrays at the aforementioned zeros of Legendre polynomials is described. A discussion of the general relationships between adjacent and accumulated tooth spacing deviations is provided. The noninsignificant measurement errors that typically arise in profile, lead, and tooth spacing deviation measurements are taken into account at each step in the work.
Use of the Generalized Transmission Error in the Equations of Motion of Gear Systems
Authors: Mark W. D.
Published: January 2010

The vibratory excitation arising from a gear pair is widely recognized to be a consequence of the nonuniform transmission of motion by the gear pair. In the preceding paper in this issue, it is shown that a three-component transmission error is required to describe the nonuniform transmission of motion by bevel gears for vibration excitation characterization purposes. The expression for the three-component transmission error derived in that paper is combined in the present paper with an analysis of the mesh forces and mesh elasticity to yield an equation of constraint involving the six degree-of-freedom unknown vibratory displacements of the gear shaft centerliners, the three unknown components of the generalized force transmitted by the mesh, and the geometric deviations of the tooth running surfaces from perfect involute surfaces which are assumed known. This matrix equation can be combined with the equations of motion of a gear system to predict the vibratory response of the system to the generalized transmission error excitation arising from meshing gear pairs within the system.
Optimal Stochastic Design of Four-Bar Mechanisms for Tolerance and Clearance
Authors: Rhyu Je Ha , Kwak Byung Man
Published: January 2010

A formulation of optimal stochastic design of mechanisms considering tolerances on the link lengths and clearances in the joints is presented. The mechanical error is analyzed for the 3σ band of confidence level through a new stochastic model of a four-bar linkage. A multiobjective optimization problem with two objective functions, mechanical error and manufacturing cost, is considered by a weighting method. Tolerance widths and nominal clearance sizes are taken as design variables. The conflicting nature between the two objectives is represented in the form of tradeoff curves. A concept of loop closure error is also introduced and applied to optimum design of the nominal linkage system and the stochastic linkage system. Numerical results are given for a four-bar function generator and a four-bar path generator.
The Image Curve of the Coupler of a Special Spherical Four Bar Linkage
Authors: McCarthy J. M.
Published: January 2010

This paper uses a kinematic mapping of spherical motion to derive an image curve which represents the coupler motion of a doubly folding spherical four bar linkage. The image curve of this linkage, the so called “kite” linkage, can be parameterized by rational functions. This parameterization is presented as well as formulas which allow the computation of its curvature and torsion at any point. These formulas provide a link between the global properties of the coupler motion as represented by the image curve itself and its instantaneous properties given by the curvature and torsion functions.
Selective Precision Synthesis of the Spatial Slider Crank Mechanism for Path and Function Generation
Authors: Premkumar P. , Dhall S. R. , Kramer S. N.
Published: January 2010

A technique for the synthesis of the RRSC spatial slider crank mechanism for path and function generation using the Selective Precision Synthesis method is presented here. Also presented is a closed form analysis technique for this mechanism. The analysis uses the spatial rotation matrices to obtain a fourth order polynomial for the coupler link rotations with the coefficients expressed in terms of the link lengths and input link rotation. This polynomial is solved in closed form to determine the coupler link rotations which are then used to determine the locations of the path point, the output link rotations, and the displacement of the slider at the cylindrical joint. For synthesis, nonlinear inequality constraint equations relating the generated and the desired path points (or slider displacements) are formulated. These constraints define accuracy neighborhoods around each of the “n” prescribed path points (or slider displacements), and are solved using the Generalized Reduced Gradient method of optimization.
Thermo-EHD Analysis of Lubrication of Helical Gears
Authors: Simon V.
Published: January 2010

The full thermal elastohydrodynamic analysis of lubrication of helical gears is presented. A numerical solution of the coupled Reynolds, elasticity, energy, and Laplace’s equations for the oil film shape, pressure and temperature distributions in the oil film, and temperature distribution in gear teeth is obtained. The effects of gear parameters and operating conditions on EHD performance characteristics is discussed. Based on the obtained results, by regression analysis, equations are derived to calculate the EHD load carrying capacity, maximum oil temperature, and power loss.
Frictional Coupling Mechanism in Multidisk Stepless Transmission With Internal Contact
Authors: Lukowski S. A. , Medeksza L. A.
Published: January 2010

Analytical studies are made of the frictional coupling mechanism in multidisk stepless transmissions with internal contact where friction elements have an initial line and point contact. The shapes of contact areas between the disks’ surfaces are considered as “deformed” rectangles and “deformed” ellipses for the line contact and the point contact, respectively. Relationships between the characteristic parameters of the frictional coupling elements are derived and expressed in the form of integrals which can be readily evaluated numerically for the transmission range and efficiency. Numerical results are presented in graphical forms for some values of parameters considered in this study.
Spectral Analysis of the Effective Temperature in Passive Solar Buildings
Authors: Kirkpatrick A. T. , Winn C. B.
Published: January 2010

The effective temperature, a linear combination of a building’s enclosure temperature, mean radiant temperature, and the ambient temperature, is a measure of the thermal comfort inside a building. Results from an analytical study of the relationship between the effective temperature, glazing areas, and thermal energy storage in passive solar buildings are presented in this paper. Spectral analysis is used to find the effective temperature response of a mixed-direct and indirect-gain passive solar building to Typical Meteorological Year (TMY) weather data. The response is given by the complex product of the building transfer functions and the weather inputs. Results are presented for the sensitivities of the maximum, minimum, and average daily effective temperature to changes in the direct and indirect gain glazing area and thermal energy storage.
On the Design of Horizontal Axis Two-Bladed Hinged Wind Turbines
Authors: Hohenemser K. H. , Swift A. H. P.
Published: January 2010

Hinged two-bladed wind turbines are not necessarily free of disturbing vibrations. The combination of elastic or built-in blade coning with blade flapping about a conventional teeter hinge produces periodic blade angular velocity variations in the blade tip path plane with associated vibrations and dynamic loads. The paper discusses and evaluates various hinge configurations for two-bladed rotors and shows why the conventional teeter hinge leads to nonuniform blade angular velocity in the blade tip path plane. The solution to this problem adopted for two-bladed helicopter rotors, though complex, could be of interest for large wind turbines. A much simpler solution, calling for the suppression of blade flapping by passive blade cyclic pitch variation produced by a strong negative pitch-flap coupling, was found to be practical for upwind tail vane stabilized two-bladed wind turbines.
Performance Testing of Small Interconnected Wind Systems
Authors: Park G. L. , Krauss O. , Miller J.
Published: January 2010

There is a need for performance information on small windmills intended for interconnected operation with utility distribution service. The owner or prospective buyer needs the data to estimate economic viability and service reliability, while the utility needs it to determine interconnection arrangements, maintain quality of power delivered by its line, and to answer customer inquiries. No existing testing program provides all the information needed, although the Rocky Flats test site comes close. To fill this need for Michigan, Consumers Power Company and the Michigan Electric Cooperative Association helped support a two-year program at Michigan State University involving extensive performance testing of an Enertech 1500 and a 4-kW Dakota with a Gemini inverter. The performance study suggested measurements necessary to characterize SWECS for interconnected operation. They include SWECS energy output to a-c line, miles of wind passing the rotor, var-hour metering for average var consumption, and recording watt, current, and voltmeters to assess SWECS output variability. Added instruments for waveform measurement (to assess power quality) are also needed. Typical data taken at the MSU test site are used to illustrate the techniques and preliminary data from a current project is given. Finally, conclusions about SWECS performance are listed.
Loss-Compensated Radiometer
Authors: Lobo P. C.
Published: January 2010

A new radiometer concept is described and evaluated. Automatic dynamic electrical compensation is achieved by a high-gain feedback amplifier and low thermal inertia solar and compensating electrical sensors. With sufficiently high gain, compensation can increase accuracy to limits determined by amplifier drift. Equations governing instrument response are derived and analyzed. Initial measurements on a preliminary prototype confirm the validity of the concept which should yield a very accurate instrument with “self calibrating” features.
Experimental Results of Pitching Moment Tests on Parabolic-Trough Solar-Collector Array Configurations
Authors: Randall D. E. , Tate R. E. , Powers D. A.
Published: January 2010

Two wind-tunnel tests were conducted to investigate specifically the pitching moment characteristics of parabolic-trough solar-collector modules deployed within a collector array. The collector modules were located within various rows of a simulated array configuration to investigate shielding effects from upstream collector rows and/or windscreen fences. Selected fence configurations and fence spacing upstream from the initial array row were studied. The test results demonstrate that pitching moment is significantly reduced by shielding provided by upstream fencing or collector rows.
Freeze-Protection Heat Loss From a Parabolic-Trough Solar System
Authors: May E. K.
Published: January 2010

The thermal energy required to prevent the freezing of water in an industrial parabolic trough solar system is quantified. Even in a cold climate, such as that of Denver, Colorado, thermal losses can be much less than 1 percent of the solar energy delivery.
An Evaluation of Solar Domestic Hot Water Control Systems
Authors: Farrington R.
Published: January 2010

Literature on solar domestic hot water (SDHW) control systems was reviewed to assess results of control system performance and reliability. Seven SDHW control systems underwent six laboratory tests: a sensor temperature response characterization, a sensor stagnation test, a controller function test, a controller vibration test, a controller environmental exposure test, and a controller inspection and high-potential test. Both the literature review and the testing indicate serious concerns with SDHW control system performance and reliability. The results of the laboratory tests included failure of 9 of 15 thermistors due to stagnation conditions, drifting of sensor response, differentials strongly dependent on the system temperature, electronic failure caused by high ambient temperatures and humidity, and the failure of the equipment to meet published specifications. Because of these problems, a control system could operate the pump when the storage tank is warmer than the collector. Because control systems for SDHW systems and active space heating systems are similar, many of the results presented here can be extrapolated to apply to active space heating control systems as well.
Improved Optical Design of Nontracking Concentrators
Authors: Kwan B. M. , Bannerot R. B.
Published: January 2010

Optical designs based on a two reflections or less criterion have been developed for one and two-facet trapezoidal concentrators. Collector designs resulting from this criterion have been evaluated with the aid of a ray-trace computer simulation which includes the effects of nonideal reflectors. Results indicate a marked increase in performance, particularly for the one-facet designs, as compared to the collectors previously designed with the one reflection or less criterion. A significant result is that when a proper accounting is made for the actual acceptance angle for the concentrators, the performances of the optimal one and two-facet designs become nearly identical, indicating that the previously held contention that improved performance could be achieved with multifaceted reflectors (geometrically approaching the compound parabolic shape) may be incorrect.
Heat Transfer Enhancement in a Paraffin Wax Thermal Storage System
Authors: Eftekhar J. , Haji-Sheikh A. , Lou D. Y. S.
Published: January 2010

Heat transfer enhancement in a thermal storage system consisting of vertically arranged fins between a heated and cooled horizontal finned-tube arrangement is reported. The high thermal expansion coefficient and low viscosity of paraffin wax, at temperatures above 50°C, are utilized to induce natural convection in the liquid phase even at small thicknesses. The experimental data on the rate of production of liquid as a function of time and temperature of the hot surface is presented. The photographs of the melted zone indicate a naturally buoyant flow induced in the neighborhood of the vertical fins causes a rapid melting of the solid wax and a downdraft along the cooler solid phase surface. The heat transfer coefficient at the interface is calculated from experimentally determined instantaneous locations of the moving boundary.
An Analytical Examination of Three Open-Cycle Cooling Systems
Authors: van Leersum J.
Published: January 2010

The equations governing the operation of three open-cycle cooling systems are simplified to make them amenable to analytical examination. Closed-form expressions are then derived for the cycle coefficients of performance and sensible and latent capacities. The relative sensitivities of these parameters to system variables are then derived.
Technical and Economic Assessment of Tethered Wind Energy Systems
Authors: Furuya O. , Maekawa S.
Published: January 2010

The wind energy existing at high altitude has been investigated as a potential energy resource in the United States. In terms of the average power density, it can be as high as 16 KW/m2 at northeastern U.S. sites such as New York, which can be compared to 0.5 KW/m2, the maximum ground level value at the U.S. sites. For a lifting generation device, a VTOL concept, new to this type of TWES, which combines the fixed wing with helicopter technology was extensively studied. The cost of electricity (COE) with such a system was determined and found to be competitive to that of fossil fuel in the near future.
The Bottom Heat Loss of a Solar Pond in the Presence of Moving Ground Water
Authors: Duyar A. , Bober W.
Published: January 2010

The bottom heat loss from a solar pond in the presence of moving ground water was determined under steady state conditions. A simplified pond model was used which restricts the results to long, narrow, shallow ponds. The analysis was based on the steady two-dimensional energy equation utilizing an effective thermal conductivity. The ground was modeled as a porous soil consisting of two distinct regions; one above the water table and one below where the ground water was assumed to flow in the horizontal direction. Solutions were obtained by the finite-difference direct method utilizing matrix concepts. The bottom heat loss is represented by a conductance coefficient whose values are plotted as a function of Peclet number, water table level, and the thermal conductivity ratio of the two distinct soil regions. The results indicate that the heat loss rate significantly increases as the water table level moves closer to the pond bottom. At water table levels close to the pond bottom, the heat loss rate increases significantly with increasing Peclet number.
Coefficients of Heat and Mass Transfer in a Packed Bed Suitable for Solar Regeneration of Aqueous Lithium Chloride Solutions
Authors: Lo¨f G. O. G. , Lenz T. G. , Rao S.
Published: January 2010

Reconcentration of a lithium chloride solution in an open-cycle absorption chiller can be accomplished by passing solar heated air through a packed column to which the dilute solution is supplied. Following a theoretical study of heat transfer and water vapor transfer rates in the column, experimental measurement of those rates was made. Heat transfer and mass transfer coefficients are correlated with rates of air and liquid flow, and with temperatures of air and liquid supply. Performance data are presented and commercial design and operating requirements are suggested.
Effect of Solar Radiation on Thermal and Hydrodynamic Conditions in Laminar, Open Channel Flow
Authors: Houf W. G. , Incropera F. P. , Viskanta R.
Published: January 2010

A three-dimensional laminar flow model has been used with a one-dimensional radiation transfer model to predict the response of a slowly moving liquid layer to solar irradiation. Calculations performed for a range of liquid velocities, liquid and substrate radiative properties, and solar irradiation reveal the important influence of buoyancy forces on hydrodynamic and thermal conditions. Buoyancy forces induce a secondary flow which takes the form of longitudinal vortices and/or ascending-descending thermals. Onset of the secondary flow may be advanced and the strength of the flow may be enhanced by increasing the irradiation and the albedo or by decreasing the extinction coefficient, substrate reflectivity, and velocity.
Height Extrapolation of Wind Data
Authors: Mikhail A. S.
Published: January 2010

Various models that are used for height extrapolation of short and long-term averaged wind speeds are discussed. Hourly averaged data from three tall meteorological towers (the NOAA Erie Tower in Colorado, the Battelle Goodnoe Hills Tower in Washington, and the WKY-TV Tower in Oklahoma), together with data from 17 candidate sites (selected for possible installation of large WECS), were used to analyze the variability of short-term average wind shear with atmospheric and surface parameters and the variability of the long-term Weibull distribution parameter with height. The exponents of a power-law model, fit to the wind speed profiles at the three meteorological towers, showed the same variability with anemometer level wind speed, stability, and surface roughness as the similarity law model. Of the four models representing short-term wind data extrapolation with height (1/7 power law, logarithmic law, power law, and modified power law), the modified power law gives the minimum rms for all candidate sites for short-term average wind speeds and the mean cube of the speed. The modified power-law model was also able to predict the upper-level scale factor for the WKY-TV and Goodnoe Hills Tower data with greater accuracy. All models were not successful in extrapolation of the Weibull shape factors.
A Compact Low-Pressure Drop Desiccant Bed for Solar Air Conditioning Applications—2: Bench Scale Tests
Authors: Kim S. , Biswas P. , Mills A. F.
Published: January 2010

Bench scale tests of a laminar flow silica gel packing element are reported. The packing is based on a coated sheet concept with a single layer of 0.25 mm silica gel particles lining narrow passages of width 1.46–3.75 mm. Adsorption and desorption tests were performed for fixed inlet conditions and a uniform initial bed condition. Measured outlet air moisture contents and air temperatures were compared with theoretical predictions and reasonable agreement obtained. The major discrepancies appear to be system related, such as excessive air bypass and inaccurate accounting for heat loss from the sides of the unit.
Biomass Production and Nutrient Removal Potential of Water Hyacinth Cultured in Sewage Effluent
Authors: Reddy K. R. , Hueston F. M. , McKim T.
Published: January 2010

Growth and nutrient uptake of water hyacinth (Eichhornia crassipes [Mart] Solms) cultured in sewage effluent were measured over a period of 1 year in a prototype wastewater treatment system which has been in operation at Walt Disney World near Orlando, Florida. Annual productivity of water hyacinth cultured in primary sewage effluent (Channel II) was found to be in the range of 5 to 27 g dry wt m−2 day−1 (23.6 dry tons acre−1 yr−1). Average growth rate during the months of May through October 1982 for hyacinth cultured in Channel II (primary sewage effluent) and Channel I (treated primary sewage effluent leaving Channel II) was about 16 g dry wt m−2 day−1 (27 dry tons acre−1 yr−1), compared to the growth rate of 13 g dry wt m−2 day−1 (22 dry tons acre−1 yr−1) for hyacinths cultured in secondary sewage effluent. Plants cultured in secondary sewage effluent generally had longer roots than the plants cultured in primary sewage effluent. A significant relationship was observed between the growth rate of hyacinth and the solar radiation. Nitrogen and P concentration of the plant tissue were higher in the hyacinths cultured during winter months compared to the plants grown in summer months. Average N and P concentration of the plants cultured in primary sewage effluent were found to be 3.7 percent N and 0.94 percent P, respectively, while the plants cultured in secondary sewage effluent had a total N and P content of 2.8 percent N and 0.79 percent P. Nutrient ratios of the major plant nutrients were found to be approximately the same as the nutrient ratios in the sewage effluent. Annual N and P uptake rates of hyacinth cultured in sewage effluent were found to be in the range of 1176 to 1193 kg N ha−1 yr−1 and 321 to 387 kg P ha−1 yr−1, respectively.
Wake Measurements Around Operating Wind Turbines
Authors: Baker R. W. , Walker S. N. , Katen P. C.
Published: January 2010

Researchers at Oregon State University have conducted wind measurement programs to describe the wake behind large horizontal axis turbines at Goodnoe Hills, Washington, (MOD-2), and behind the FloWind vertical axis wind turbine near Ellenburg, Washington. Wake measurements were taken using portable kite anemometers as well as fixed place anemometers under several atmospheric stability conditions and turbine operating conditions. Centerline hub height (midrotor) measurements were taken downwind and crosswind from 3–9 diameters. These wake programs are discussed and the velocity deficits measured are compared to the estimated deficits calculated from wake models.
Promising Control Alternatives for Solar Water Heating Systems
Authors: Wuestling M. D. , Klein S. A. , Duffie J. A.
Published: January 2010

Although the performance of solar domestic hot water (SDHW) systems has been well studied, there are several promising control alternatives that have not been thoroughly investigated. Reduced constant collector fluid flow rates, variable collector flow rates, and variable volume storage are several alternative strategies. This paper presents the results of an analytical study using the TRNSYS simulation program in which the thermal performance of SDHW systems utilizing alternative control strategies are compared while operating under realistic conditions in several different climates of the United States. The effects on system performance of time of year, collector area and quality, preheat storage tank volume and energy losses, occurrence of mixing the preheat storage tank, controller temperature deadbands, auxiliary set temperature, total daily usage, and load distribution are investigated.
Design, Construction, and Initial Operation of the Los Alamos National Laboratory Salt-Gradient Solar Pond
Authors: Jones G. F. , Meyer K. A. , Hedstrom J. C. , Dreicer J. S.
Published: January 2010

This paper discusses the design, construction, and initial operation of the solar pond at Los Alamos National Laboratory. This 232 m2 pond is the third facet of a threefold approach to the study of hydrodynamic effects in double diffusive systems, such as solar ponds. The first two facets are flow visualization experiments and one-dimensional laboratory tank tests [1]. Data from these experiments, in addition to other data from the literature, are used to validate the one-dimensional dynamic performance pond model developed by one of the authors [2]. Our particular interest is the boundary-layer structure at the interfaces between the convecting and nonconvecting zones, interaction between the zones, and surface zone effects including diurnal heating effects and wind-induced turbulence. A pond, such as the one this paper describes, provides possible insight into several pond physical processes that may not occur in smaller-scale laboratory experiments due to edge effects, or may be impossible to simulate.
Field Experiments in Aquifer Thermal Energy Storage
Authors: Melville J. G. , Molz F. J. , Gu¨ven O.
Published: January 2010

Large scale field experiments in aquifer thermal energy storage (ATES) were conducted between September, 1976, and November, 1982. Volumes of 7,700 m3, 54,800 m3, 58,000 m3, 24,400 m3, 58,000 m3, and 58,680 m3 were injected at average temperatures of 35.0° C, 55.0° C, 55.0° C, 58.5° C, 81.0° C, and 79.0° C, respectively, in an aquifer with ambient temperature of 20.0° C. Based on recovery volumes equal to the injection volumes, the respective energy recovery efficiencies were 69, 65, 74, 56, 45, and 42 percent. Primary factors in reduction of efficiency were aquifer nonhomogeneity and especially convection due to buoyancy of the injection volumes.
The NBS Solar Collector Reliability/Durability Test Program: Summary of Results and Recommendations for Collector Testing
Authors: Waksman D. , Thomas W. C.
Published: January 2010

Efforts in the development of reliability/durability tests for solar collectors and their materials have been hampered by the lack of real time and accelerated degradation data that can be correlated with in-use conditions. In 1977, the Solar Collector Reliability/Durability Test Program was initiated by the US Department of Energy at the National Bureau of Standards (NBS) to help generate the data required to develop methods for predicting the long term durability and reliability of flat-plate solar collectors and their materials. This paper summarizes the results obtained in the test program for full-size solar collectors. Recommendations are made regarding the use and limitations of thermal performance measurements and environmental exposure tests for assessing the durability of flat-plate solar collectors.
Parabolic Solar Collector With Glass Pipe and Black Fluid
Authors: Chang M. J. , Roux J. A.
Published: January 2010

A glass pipe and an absorbing black fluid were combined with a parabolic solar reflector into a solar collector. Thermal efficiencies for three different types of receivers with a parabolic trough solar reflector were compared: (1) single glass pipe with black fluid, (2) concentric annulus glass pipes with black fluid, and (3) black-painted copper tubing. The single glass pipe with a black working fluid performed best experimentally. The single glass pipe with a black fluid was better than the black painted copper tube by an average value of 5 percent absolute system efficiency or 14 percent on a total energy absorbed basis. Mass flow rate and wind speed were analytically found to be significant. The black fluid solar collector was found to have an optimum system efficiency for a blackening agent concentration of 15 ml per gallon of water. A numerical lumped heat capacity model was used to compare with the experimental data.
Testing of the US Solar Pilot Plant Receiver
Authors: Friefeld J. M. , Coleman G. C.
Published: January 2010

The US Department of Energy (DOE) is actively engaged in the design and construction of America’s first Solar Thermal Electric Pilot Plant at Barstow, California. Preconstruction tests of the external, single-pass-to-superheat, water/steam receiver under actual solar operating conditions were conducted to validate the design at the earliest possible date to assure the achievement of Pilot Plant operating goals. Receiver steady-state and transient operating characteristics and performance were investigated during clear day, intermittent cloud, and simulated emergency situations. Testing concluded with limited testing of the receiver at flux and power levels above the maximum expected Pilot Plant conditions. The test program successfully achieved the overall objective of confirming the design of the Pilot Plant solar receiver.
Heat Transfer in a Liquid Convective Diode
Authors: Jones G. F.
Published: January 2010

The dynamic behavior of a liquid convective diode for space heating of passive solar buildings is analyzed and explained by experiments and theory. The experiments include flow visualization and temperature measurements obtained for a diode installed in the laboratory and temperature measurements obtained for three diodes installed in a test cell during the winter. We present a first-principles analytical model to predict diode time-temperature histories and performance. A comparison of predicted temperatures and solar energy contribution with data obtained for the test cell experiment showed excellent agreement. The good agreement indicates that the model contains the elements necessary to accurately predict site-specific diode performance and temperatures. The thermal efficiency of the diode system installed in the test cell is calculated. The data show that the diode system outperforms all other non-phase-change passive solar heating components. A thermal efficiency of 50 percent over a three-month winter period is obtained for the diode. We suggest and discuss improvements to present-day diode designs that may increase performance to as high as 65 percent.
Simultaneous Transport of Heat and Adsorbate in Closed Type Adsorption Cooling System Utilizing Solar Heat
Authors: Sakoda A. , Suzuki M.
Published: January 2010

Quantitative analyses are tried for the simultaneous transport of heat and adsorbate in the operation of a closed-type solar-powered adsorption cooling system. Experimental results obtained with a small-scale unit are successfully interpreted by the model proposed here, which takes into account adsorption properties of a combination of adsorbate and adsorbent employed in the system, structures of the equipment, and its operating conditions. Also, the coefficient of performances of the system of various conditions are estimated by numerical simulations on the basis of the model. Structures of the container of adsorbents are optimized to provide larger COP.
Derivation of Universal Error Parameters for Comprehensive Optical Analysis of Parabolic Troughs
Authors: Gu¨ven H. M. , Bannerot R. B.
Published: January 2010

A study is presented where potential optical errors in parabolic troughs are divided into two groups: random and nonrandom. It is shown that the intercept factor is a function of both random and nonrandom errors as well as geometric parameters such as concentration ratio and rim angle. Three error parameters, universal to all collector geometries, that is, “universal” error parameters which combine random and nonrandom errors with collector geometric parameters, are derived analytically. The mathematical derivation of these universal error parameters is presented. A numerical technique, a detailed ray-trace computer routine which maps rays from elemental reflector surfaces to the absorber surface, is used to validate the existence of the universal error parameters. The universal error parameters are made up of one universal random error parameter, σ* ( =σC), and two universal nonrandom error parameters, β* ( = βC) and d* (=(dr)y/D). The use of universal error parameters for comprehensive optical analysis of troughs is also presented.
Latent Thermal Storage Unit Using Form-Stable High Density Polyethylene; Part I: Performance of the Storage Unit
Authors: Kamimoto M. , Abe Y. , Sawata S. , Tani T. , Ozawa T.
Published: January 2010

A latent thermal storage unit of 30 kWh using form-stable high density polyethylene (HDPE) rods has been developed mainly for solar thermal applications, and heat transfer experiments have been carried out. A direct contact heat transfer technique between HDPE rods and ethylene glycol (EG: a heat transfer fluid) is adopted. Charge and discharge characteristics have been obtained for various thermal input/output and different initial temperature profiles in the storage unit. The direct contact heat transfer and a formation of a clear thermocline provide a good performance for all the cases. Discussions are given of thermal efficiency, storage density, and thermal insulation.
Obtaining Solar Collector Cover-Plate Transmissivities From a Solar Simulator
Authors: Fintel B. W. , Jakubowski G. S.
Published: January 2010

Transmissivities, as a function of incident solar angle, were experimentally determined for various commercially available cover-plate materials using actual outdoor and indoor simulated solar conditions. The glazing materials tested were float glass, plexiglass, fiberglass, and several window films. Since the optical properties of many of these materials are not readily available, the transmissivities could not be calculated analytically. Therefore, the experimental method proved to be invaluable. Furthermore, transmissivities determined from indoor data were found to be in close agreement with outdoor results, making the simulator a practical tool. The transmissivities determined and the methods provided in this paper can be valuable in the design of solar collectors.
Quantum Criticality in an Ising Chain: Experimental Evidence for Emergent E
8
Symmetry
Authors: Coldea R. , Tennant D. A. , Wheeler E. M. , Wawrzynska E. , Prabhakaran D. , Telling M. , Habicht K. , Smeibidl P. , Kiefer K.
Published: January 2010

Hidden Symmetry Revealed

It is not often that an exact theory can describe a many-particle quantum-mechanical system, but one of the few exceptions is the behavior of a string of ferromagnets—an Ising chain—at magnetic field strengths that separate different types of ordering. Its excitations were predicted 20 years ago to be governed by the symmetry group E8, one of the most intriguing objects in mathematics. Now,

Coldea
et al.

(p.
177
) report direct experimental confirmation of this result in a quasi-one-dimensional Ising ferromagnet CoNb
2
O
6
, which they probed by neutron scattering. Two of the eight predicted excitations could be observed. Moreover, the ratio of the two lowest excitations is in quantitative agreement with the so-called “golden ratio” predicted by theory.
Topology Links RNA Secondary Structure with Global Conformation, Dynamics, and Adaptation
Authors: Bailor Maximillian H. , Sun Xiaoyan , Al-Hashimi Hashim M.
Published: January 2010

RNA Structural Principles Revealed

The thermodynamic principles that link RNA primary and secondary structure are well understood, but the relation to tertiary structure is unclear. To gain insight,

Bailor
et al.

(p.
202
) analyzed all available three-dimensional structures of an important RNA motif, the two-way junction, and found that flanking helices sample only a small percentage of possible interhelical orientations. They identified a set of general rules for the relative orientation of helices as a function of the size of the interconnecting junction. The results also rationalize how ligands stabilize specific conformations. Understanding the topological constraints that define RNA global conformation and dynamic adaptation provides guiding principles for rational manipulation of RNA structure.
Electron Nematic Phases Proliferate
Authors: Fradkin Eduardo , Kivelson Steven A.
Published: January 2010

A form of electron ordering similar to that of molecules in liquid crystals has been observed in an iron-based superconductor.
After Long March, Scientists Create 'Chinese NIH'
Authors: Jiao Li
Published: January 2010

Last week, the National Natural Science Foundation of China launched a medical department that expects to disburse about 1 billion renminbi ($150 million) in government grants in 2010.
From Medfly to Moth: Raising a Buzz of Dissent
Authors: Chen Ingfei
Published: January 2010

Twenty years after California's Medfly wars, a vocal critic of government eradication policies is back in a battle over a new invader: the light brown apple moth from Australia.
Construction of Recombinant Attenuated
Salmonella enterica
Serovar Typhimurium Vaccine Vector Strains for Safety in Newborn and Infant Mice
Authors: Gunn Bronwyn M. , Wanda Soo-Young , Burshell Dana , Wang Caihong , Curtiss Roy
Published: January 2010

Recombinant bacterial vaccines must be safe, efficacious, and well tolerated, especially when administered to newborns and infants to prevent diseases of early childhood. Many means of attenuation have been shown to render vaccine strains susceptible to host defenses or unable to colonize lymphoid tissue effectively, thus decreasing their immunogenicity. We have constructed recombinant attenuated
Salmonella
vaccine strains that display high levels of attenuation while retaining the ability to induce high levels of immunogenicity and are well tolerated in high doses when administered to infant mice as young as 24 h old. The strains contain three means of regulated delayed attenuation, as well as a constellation of additional mutations that aid in enhancing safety, regulate antigen expression, and reduce disease symptoms commonly associated with
Salmonella
infection. The vaccine strains are well tolerated when orally administered to infant mice 24 h old at doses as high as 3.5 × 10
8
CFU.
Comparison of Recombinant Proteins fromSchistosoma japonicumfor Schistosomiasis Diagnosis
Authors: Jin Ya-mei , Lu Ke , Zhou Wei-Fang , Fu Zhi-Qiang , Liu Jin-Ming , Shi Yao-Jun , Li Hao , Lin Jiao-Jiao
Published: January 2010

The most important animal reservoirs ofSchistosoma japonicumin China are bovines. Diagnosis and control of bovine schistosomiasis is critical for reducing the prevalence of the disease. We screened defined diagnostic antigens that have the potential to increase the sensitivity and specificity of serological assays and to distinguish between active and prior infections. Five recombinant proteins with the potential to be diagnostic antigens were compared to the native soluble egg antigen preparation by enzyme-linked immunosorbent assay (ELISA). We evaluated the potentials of the recombinant proteins for discriminating active from prior infections, as well as the therapeutic efficacy of the established ELISA technique.
Comparison of Polyurethane Foam to Nylon Flocked Swabs for Collection of Secretions from the Anterior Nares in Performance of a Rapid Influenza Virus Antigen Test in a Pediatric Emergency Department
Authors: Scansen Kimberly A. , Bonsu Bema K. , Stoner Erin , Mack Kathy , Salamon Douglas , Leber Amy , Marcon Mario J.
Published: January 2010

Rapid antigen testing of upper respiratory secretions collected with various swab types is often utilized for laboratory diagnoses of influenza virus infection. There are limited data on the effects of swab composition on test performance. This study compared the performance of the Quidel QuickVue Influenza A+B test on secretions from the anterior nares when a polyurethane foam swab was used for collection to that when a nylon flocked swab was used for collection. One hundred subjects who presented to a pediatric emergency department with symptoms suggestive of an influenza virus infection were recruited for the study. Foam and flocked swabs of the anterior nares were obtained from separate nares of each subject before a posterior nasopharyngeal swab was collected and placed into viral transport medium. The QuickVue test was performed directly on each swab type, and the results were compared to the results of reverse transcription-PCR (RT-PCR), direct fluorescent antibody (DFA) test, and viral culture performed on the transport medium. RT-PCR alone and DFA combined with culture were utilized as separate gold standards. There were 56 cases of influenza detected by RT-PCR; the QuickVue test was positive for 40 foam and 30 flocked swabs, for sensitivities of 71% and 54%, respectively (
P
= 0.01). Similarly, there were 49 influenza cases detected by DFA and/or culture; the QuickVue test was positive for 38 foam and 30 flocked swabs, for sensitivities of 78% and 61%, respectively (
P
= 0.13). This study suggests that polyurethane foam swabs perform better than nylon flocked swabs for the collection of secretions from anterior nares in the Quidel QuickVue Influenza A+B test.
Rapid Identification and Discrimination of
Brucella
Isolates by Use of Real-Time PCR and High-Resolution Melt Analysis
Authors: Winchell Jonas M. , Wolff Bernard J. , Tiller Rebekah , Bowen Michael D. , Hoffmaster Alex R.
Published: January 2010

Definitive identification of
Brucella
species remains a challenge due to the high degree of genetic homology shared within the genus. We report the development of a molecular technique which utilizes real-time PCR followed by high-resolution melt (HRM) curve analysis to reliably type members of this genus. Using a panel of seven primer sets, we tested 153
Brucella
spp. isolates with >99% accuracy compared to traditional techniques. This assay provides a useful diagnostic tool that can rapidly type
Brucella
isolates and has the potential to detect novel species. This approach may also prove helpful for clinical, epidemiological and veterinary investigations.