bluuebunny/crossref_metadata_2025 huggingface dataset:
Screening and Analysis of Potential Filler Materials for Molten Salt Thermocline Storages
Authors: Martin Claudia , Breidenbach Nils , Eck Markus
Published: October 2014

Solar thermal power plants are a promising option for future solar electricity generation. Their main advantage is the possibility to utilize integrated thermal storage capacities, allowing electricity generation on demand. In state of the art solar thermal power plants, two-tank molten-salt thermal energy storages are used. Significant cost reductions are expected by using thermocline thermal energy storage by storing the liquid storage material inside a single tank when compared to a two tank storage system. By embedding a low cost solid filler material inside the storage tank further cost reductions can be achieved.

In earlier studies [1, 2] several potential filler materials have been investigated. In these study quartzite turned out to be a promising candidate due to its satisfying thermal stability and availability. At a temperature of approx. 573°C the crystal structure of quartzite changes from trigonal α-quartz phase to the hexagonal β-quartz phase [3]. This quartz conversion results in a volume change [4] that may cause cracking of the quartzite crystals due to weight loads in a packed bed. Since these thermal tests of the study mentioned were limited to 500°C this dunting was not considered. Thus, despite of the published studies there is a need for further, more detailed analysis.

One trend in today’s development of solar thermal power plants is to use molten salt as storage material and heat transfer fluid at operating temperatures of 560°C and above. Accordingly, the quartz inversion might limit the applicability of quartzite as a filler material at elevated operating temperatures. Due to this concern, an investigation has been started to investigate the utilizability of natural rocks as low cost filler materials.

In the first phase of this investigation a comprehensive literature survey was conducted. Based on this study, magmatic and sedimentary rocks turned out to the most promising rock classes for this application. For the further investigation, basalt was chosen as a suited representative for magmatic and quartzite for sedimentary rocks. In lab-scale tests, these candidate materials were investigated with respect to their:

• Calcite content

• Thermal stability up to 900°C in air

• Thermal stability up to 560°C in molten salt

• Cyclic stability between 290°C and 560°C in molten salt

• Specific heat capacity up to 600°C

In this paper the results of these investigations are presented and future activities are outlined.
A Levelized Cost Metric for EDS-Based Cleaning of Mirrors in CSP Power Plants
Authors: Joglekar Nitin , Guzelsu Emre , Mazumder Malay , Botts Adam , Ho Clifford
Published: October 2014

Integration of electro-dynamic screens (EDS) on mirrors in CSP power plants is an emergent and environmentally conservative technology. It can remove the deposited dust from these mirrors and thus maintain high reflectivity continuously through the plant life. We propose a levelized cost of mirror cleaning (LCOMC) metric to link the EDS-enhanced reflectivity gains with the relevant product and installation costs, as well as with the direct and indirect costs associated with plant operation and maintenance. The LCOMC metric accounts for the fact that enhanced reflectivity owing to EDS technology allows the plant operators to specify a suitably smaller optical capacity plant in order to deliver a fixed power production target. We illustrate our proposal with a dataset on deluge cleaning of a scaled solar power plant configuration. For the configuration studied, it is shown that, if the EDS technology production and installation cost is $10/m2, then its LCOMC is 7.9% below the LCOMC for a comparable deluge cleaning alternative. Thus, the proposed LCOMC metric provides a methodology for systemic assessment of the economic impact of the EDS technology (and other mirror cleaning technologies), early in its technology development cycle.
A Novel Portable Device to Measure Transmittance and Reflectance of Parabolic Trough Receiver Tubes in the Field
Authors: Espinosa-Rueda Guillermo , Martinez-Sanz Noelia , Izquierdo-Nuñez David , Osta-Lombardo Marta
Published: October 2014

The performance of parabolic trough (PT) receiver tubes (RT) has a direct impact on concentrated solar power (CSP) plant production. As a result, one major need of operation and maintenance (O&M) in operating plants is to monitor the state of the receiver tube as a key element in the solar field. In order to fulfill this necessity, Abengoa Solar has developed the first existing portable device for measuring transmittance and reflectance of parabolic trough receiver tubes directly in the field. This paper offers a description of the technical features of the instrument and reviews the issues related to its usability as a workable portable device in operating solar fields. To evaluate its performance, laboratory studies have been carried out using two patterns to determine the accuracy and standard deviation of the measurements, obtaining excellent results.

This information is complemented with data collected by O&M using this instrument in solar power plants. Studies have been carried out to determine the effect of both rainfall and artificial cleaning on the increase of transmittance. These values are then compared to those obtained from hand-cleaning and show important differences. The results are discussed in this paper.
Integrated Computational and Experimental Framework on Advanced Flow Battery for Renewable Power Plant Applications
Authors: Listenbee Ryan , Jeong Kwangkook , McCann Roy
Published: October 2014

A study has been conducted to develop advanced vanadium redox flow battery (VRFB) for renewable energy storage applications using integrated computational and experimental framework. Analytical modeling has been performed to predict electrical outputs based on combined approach including fluid mechanics, electrochemistry, and electric circuit. A lab-scale experimental setup has been designed and built to validate the modeling results.

The VRFB project has been collaborated between Arkansas State University Jonesboro and University of Arkansas Fayetteville to focus on pin pointing the transient characteristics of the vanadium redox flow battery in terms of chemical reaction, fluid flow, and electric circuit by obtaining exact solutions from the associated governing differential equations using a numerical approach. To obtain comparable experimental data, a test bed made of two half cells is constructed and joined together by a permeable membrane designed to facilitate ion transfer between two separate vanadium electrolytes, and then the system will be scaled up to multiple cell stacks.

This research aims to better understand the transient characteristics of the VRFB in order to refine the system in hopes of improving efficiency. In turn alternative energy such as multi megawatt wind and solar farms should gain more support as the ability to store energy becomes more reliable and economically feasible. This paper will focus on the steps taken to validate the supporting mathematical models, and the preliminary results of the tests conducted using the VRFB test bed. Future work will be addressed to develop a pilot-scale VRFB with enhanced efficiency and temperature limits.
Computational Analysis of Particulate Storage Bin for High Temperature Thermal Energy Storage
Authors: Roop Jonathan , Jeter Sheldon , Al-Ansary Hany , El-Leathy Abdelrahman , Abdel-Khalik Said I.
Published: October 2014

The Riyadh Techno Valley Solar Tower, an innovative type of concentrator solar power plant, is being developed by King Saud University (KSU) and Georgia Tech (GT). The facility is being constructed at the Riyadh Techno Valley development near the KSU campus and will store thermal energy collected from the sun in solid particles, which can be heated to higher temperatures than is currently possible using molten salts. The particles must be well insulated to stop energy loss to the environment. Hence, GT and KSU have incorporated an insulated storage bin into the plant design.

The bin will be constructed in several layers: an inner layer of firebrick, which can endure direct exposure to the heated particles; a specially prepared refractory insulating concrete, which maintains good insulating value at high temperatures; and a conventional structural concrete shell surrounding the entire bin. This paper presents a thermal analysis of this storage device and discusses structural analyses. Simplified analytical solutions are compared with the finite element results from a 3D ANSYS model of the entire bin. A temperature distribution is obtained, and heat loss through the bin is also evaluated.

Modeling of rebar and concrete cracking are described, and methods of reducing stress on the outer concrete shell are considered. Structural support for an access tunnel into the bin is also explored. The current tunnel design involves a material with a relatively high thermal conductivity, necessitating modifications to the bin. Finally, material selection is considered, particularly with regard to the insulating concrete layer. Limitations on the use of Portland cement based insulating concretes are discussed, and alternative base materials are evaluated.
Enhanced Durability Transparent Superhydrophobic Anti-Soiling Coatings for CSP Applications
Authors: Polizos Georgios , Schaeffer Daniel A. , Smith D. Barton , Lee Dominic F. , Datskos Panos G. , Hunter Scott R.
Published: October 2014

Optically transparent superhydrophobic (SH) coatings based on multifunctional silica nanoparticles and polymeric binders were developed and their optical and abrasion resistance properties were studied. Three key factors are emphasized: i) The optical clarity of the coatings. Particle deagglomeration and surface functionalization techniques were developed to obtain particle size distributions with an average size smaller than 200 nm. The particles were uniformly dispersed in organic binders and resulted in coatings with an average roughness value smaller than 30 nm. The nano-sized particles do not scatter light at wavelengths > 250 nm because of their small dimensions. ii) Enhanced particle-binder interfaces. We have introduced a double functionality on the particle’s surface in order to partially crosslink them with the polymeric binder. This multifunctional configuration significantly improves the abrasion resistance of the coatings without degrading their SH properties. iii) Accelerated weathering durability. Coatings were subjected to simulated solar UV exposure. Our ongoing studies indicate that the coatings are environmentally durable over several years of simulated UVA exposure. The nanostructure-property interdependencies underlined in the above three key factors are utilized in the development of transparent SH coatings with enhanced durability.
Modeling of Transient Energy Loss From a Cylindrical-Shaped Solid Particle Thermal Energy Storage Tank for Central Receiver Applications
Authors: Djajadiwinata Eldwin , Al-Ansary Hany , Danish Syed , El-Leathy Abdelrahman , Al-Suhaibani Zeyad
Published: October 2014

The use of solid particles as a heat transfer and thermal energy storage (TES) medium in central receiver systems has received renewed attention in recent years due to the ability of achieving high temperatures and the potential reduction in receiver and TES costs. Performance of TES systems is primarily characterized by the percentage of heat loss they allow over a prescribed period of time. Accurate estimation of this parameter requires special attention to the transient nature of the process of charging the TES bin during solar field operation and discharging during nighttime or at periods where solar field operation is interrupted. In this study, a numerical model is built to simulate the charge-discharge cycle of a small cylindrical-shaped TES bin that is currently under construction. This bin is integrated into the tower of an experimental 300-kW (thermal) central receiver field being built in Riyadh, Saudi Arabia, for solid particle receiver research, most notably on-sun testing of the falling particle receiver concept within the context of a SunShot project. The model utilizes a type of wall construction that had been previously identified as showing favorable structural characteristics and being able to withstand high temperatures. The model takes into account the anticipated charge-discharge particle flow rates, and includes an insulating layer at the ceiling of the bin to minimize heat loss by convection and radiation to the receiver cavity located immediately over the TES bin. Results show that energy loss during the full charge-discharge cycle is 4.9% and 5.9% for a 5-hour and 17-hour discharge period, respectively. While large, these energy loss values are primarily due to the high surface-to-volume ratio of the small TES bin being investigated. Preliminary analysis shows that a utility-scale TES bin using the same concept will have an energy loss of less than 1%.
Sintering of Solid Particulates Under Elevated Temperature and Pressure in Large Storage Bins for Thermal Energy Storage
Authors: Knott R. C. , Sadowski D. L. , Jeter S. M. , Abdel-Khalik S. I. , Al-Ansary H. A. , El-Leathy Abdelrahman
Published: October 2014

This research is a part of the DOE-funded SunShot project on “High Temperature Falling Particle Receiver.” Storing thermal energy using solid particulates is a way to mitigate the time of day dependency of concentrated solar power. Small particles may be stored easily, and can be used as a heat transfer medium to transfer heat to the power cycle working fluid through a heat exchanger. This study examines the physical characteristics of solid particulates of different materials kept inside large storage containers. Particle behavior at the expected high temperatures of the concentrated solar power cycle combined with the elevated pressure experienced within the storage container must be evaluated to assess the impact on their physical properties and ensure that the particles would not sinter thereby impacting flow through the system components particularly the receiver and heat exchanger. Sintering is a process of fusing two or more particles together to form a larger agglomerate. In the proposed concentrated solar power tower design, particles will experience temperatures from 600°C to 1000°C. The increase in temperature changes the physical characteristics of the particle, along with any impurities that could form particle to particle bonds. In addition, the hydrostatic pressure exerted on particles stored inside a storage unit increases the probability of sintering. Thus, it is important to examine the characteristics of particles under elevated temperatures and pressures.

The experimental procedure involves heating particulates of a known mass and size distribution to temperatures between 600°C and 1000°C inside a crucible. As the temperature is held constant, the particulate sample is pressed upon by a piston pushing into the crucible with a known constant pressure. This process is repeated for different temperatures and pressures for varying lengths of time. The resulting particulates are cooled, and their size distribution is measured to determine the extent of sintering, if any, during the experiment. The particulates tested include various types of sand, along with alumina particles. The data from this experiment will allow designers of storage bins for the solid particulates to determine when significant sintering is expected to occur.
Hydrodynamic Direct Carbon Fuel Cell
Authors: Bloomfield Valerie J. , Townsend Robert
Published: October 2014

There are many possibilities for the direct carbon fuel cell approach including hydroxide and molten carbonate electrolytes, solid oxides capable of consuming dry carbon, and hybrids of solid oxide and molten carbonate technologies. The challenges in fabricating this type of fuel cell are many including how to transport the dry solids into the reactant chamber and how to transport the spent fuel (ash) out of the chamber for continuous operation[1]. We accomplish ash removal by utilizing a hydrodynamic approach, where inert gas or steam is injected into the anode chamber causing the carbon particles to circulate. This provides a means of moving the particles to a location where they can be separated or removed from the system. The graphic below illustrates how we segregate the spent fuel from the fresh fuel by creating multiple chambers. Each sequential chamber will have a reduced performance until the fuel is fully spent. At that point, the electrolyte/ash mixture can be removed from the cell area and cleaned for recycling or discarded.
Development and Evaluation of Prototype Transparent Electrodynamic Screen (EDS) Integrated Solar Collectors for Automated Dust Removal
Authors: Hudelson John N. , Stark Jeremy , Gibson Hannah , Hao Fang , Xu Zhongkai , Mazumder Malay , Horenstein Mark N.
Published: October 2014

The integration of transparent electro-dynamic screen (EDS) on the front surface of solar mirrors and glass cover plates of photovoltaic panels has a strong potential to significantly reduce the frequency of water-based cleaning needed to mitigate losses from dust depositions present in arid regions. The objective of our research was to develop and evaluate prototype transparent EDS-integrated mirrors and solar panels for their self-cleaning functions, with an aim to keep the collectors clean at a low cost without water or manual labor. This paper focuses on the design, fabrication, and laboratory evaluation of a prototype EDS integrated second surface mirrors and solar panels. The EDS consists of a set of parallel transparent electrodes screen-printed on the optical surface and embedded in a thin transparent dielectric film. By applying three-phase, low current, low frequency high voltage-pulses to the electrodes, electro-dynamic repulsion forces and a traveling wave are created for removing dust particles from the surface of the collectors. Design and construction of an environmental test chamber to simulate different atmospheric conditions of semi-arid and arid areas with respect to temperature, RH, and dust deposition conditions are briefly described. A non-contact specular reflectometer was designed, constructed and calibrated for measuring specular reflection efficiency of the mirrors. Laboratory evaluation of the performance of the EDS-integrated collectors was completed using humidity controlled environment test chamber where the prototype mirrors and panels were examined for their self-cleaning action. In each experiment, the solar collectors were loaded with dust until the specular reflectance of the test mirror or the short circuit current of the panel showed a significant decrease. The EDS was then operated for one minute and the relative output was recorded. The results show that the specular reflectivity of EDS mirrors and the short circuit current of the EDS panels can be restored by more than 90% of the values measured under the clean conditions.
Thermal Simulation of an Off-Grid Zero Emissions Building
Authors: Ordonez J. C. , Yang S. , Ordonez C. , Vargas J. V. C. , Solano T. , Bublitz M. , Collins E.
Published: October 2014

This paper presents a simulation of the thermal response of the off-grid zero emissions building at the Florida State University Energy and Sustainability Center in efforts to assess the development of effective thermal management strategies for the building. The paper describes the OGZEB and its energy systems and presents a thermal model to compute the temperature and humidity distribution using a volume element methodology. The energy characterization conducted in this paper will be used in future studies to develop control strategies and minimize energy consumption.
Evaluation of Increased Discretization of Real-Time Locational Marginal Prices on Customer-Optimized Distributed Generation
Authors: Duthu Ray C. , Bradley Thomas H.
Published: October 2014

This article presents an economic model for customer-owned and operated distributed generation facilities operated according to net metered, real-time pricing (RTP). Previous research has demonstrated that within traditional billing and rate structures customer-optimized distributed generation facilities create quantifiable losses for distribution and generation and transmission utilities. Using historical real-time pricing data available on the New England ISO website, a customer-optimized dispatch of distributed generation is constructed so that total consumer costs are minimized. The relative difference of consumer behavior is compared between RTPs with hour-long and a five minute long periods. The results are presented across a range of DG prices, and the utilization and value of the DG resource in this case study is also quantified.
Development of the Renewable Energy Deployment and Display (REDD) Facility at the Desert Research Institute
Authors: Damm Christopher , Strobach Elise , Robbins Curtis , Broch Amber , Turner Robert , Hoekman S. Kent
Published: October 2014

The Desert Research Institute (DRI) has developed a Renewable Energy Deployment and Display (REDD) Facility as an off-grid capable facility for exploration of integration, control, and optimization of distributed energy resources (DER) with an emphasis on solar and wind energy. The primary goal of the facility is to help grow DRI’s capabilities and expertise in areas of renewable energy research, development, demonstration, and deployment. The facility is powered by four solar PV arrays (6 kW total) and two wind turbines (3 kW total) during off-grid operation. Energy storage is achieved via two 2.5 m3 hydrogen storage tanks and a 9 kWh battery bank. The hydrogen is produced via a 5 kW electrolyzer and is used to fuel an internal combustion engine (ICE) with an alternator when needed.

The REDD Facility consists of a 111.5 m2 residence and a 56 m2 workshop. The REDD House features over 37 m2 of solar thermal collectors used to provide hot water to either a 15.9 kW heat exchanger or a 17.6 kW absorption chiller. The REDD Workshop features a 54 m2 solar collector air heater and thermal storage via water and air in the floor. Also housed in the REDD Workshop is a modified 3-cylinder 950cc naturally aspirated renewable gas engine connected to a 5 kW generator to be used for future biomass-related research.

Future research at the REDD Facility will include continued investigation into the use and regulation of site-built solar air collectors, solar cooling technologies, and the advancement of hydrogen as energy storage for residential applications. The facility is also continually used for education and outreach purposes. Lastly, DRI encourages the use of the REDD Facility as a test bench for new technologies; whether for proof of concept or demonstration.
Numerical Design of a Planar High-Flux Microchannel Solar Receiver
Authors: Rymal Charles J. , Apte Sourabh V. , Narayanan Vinod , Drost Kevin
Published: October 2014

This paper discuses the design of several micro-channel solar receiver devices. Due to enhanced heat transfer in micro-channels, these devices can achieve a higher surface efficiency than current receiver technology, leading to an increase in overall plant efficiency. The goal is to design an efficient solar receiver based on use of super-critical carbon-dioxide and molten salt as heat-transfer fluids. The super-critical Brayton cycle has shown potential for a higher efficiency than current power cycles used in CSP. Molten salt has been used in CSP applications in the past. The required inlet and outlet temperatures of the fluid are 773.15 K and 923.15 K for carbon-dioxide and 573.15 K and 873.15 K for molten salt. These temperature values are determined by the power cycles the devices are designed to operate in. The required maximum pressure drop is 0.35 bar for carbon-dioxide and 1 bar for molten salt. These pressure values are intended to be a practical goal for maximum pressure drop. The super-critical carbon-dioxide power cycle requires an operating pressure of is 120 bar. Finally, each device must withstand any mechanical and thermal stresses that may exist. Devices presented range in size from 1 cm2 to 4 cm2 and in heat transfer rates from 200 W to 400 W. The size of the device is based on the output capacity of the solar simulator which will be used for testing. For carbon-dioxide, three designs were developed with varying manufacturability. The low risk design features machined and welded parts and straight parallel channels. The medium risk design features machined and diffusion bonded parts and straight parallel channels. The high risk design features a circular micro-pin-fin array created using EDM and is constructed using diffusion bonding. The absence of high operating pressure for molten salt made structural design much easier than for carbon-dioxide. Conjugate heat-transfer simulations of each design were used to evaluate pressure drop, receiver efficiency, and flow distribution. Two and three dimensional structural analyses were used to ensure that the devices would withstand the mechanical and thermal stresses. Based on the numerical analyses, a receiver efficiency of 89.7% with a pressure drop of 0.2 bar were achieved for carbon-dioxide. The design was found to have a structural safety factor of 1.3 based maximum mechanical stress occurring in the headers. For molten salt, an efficiency of 92.1% was achieved with a pressure drop of 0.5 bar.
Development of a Building-Specific, Multi-Criteria Energy Technology Portfolio Evaluation Approach
Authors: Zhang Linyu , Li Yongchang , Duncan Scott , Kim Juhyun , Mavris Dimitri
Published: October 2014

An accurate building energy technology portfolio evaluation approach is needed that integrates physics-based models and business case analysis. Open source, parametric building modeling tools have recently matured to enable system-level building energy analysis at high fidelities. It is observed that these modeling tools usually only analyze energy savings and are not concerned with other criteria often factored into the choice of an energy technology portfolio. This paper presents an approach to constructing a parametric, physics-based, building-specific, business case analysis tool for quantifying multi-criteria performance of building energy technology portfolios. The resulting environment, which is used to build up a portfolio step-by-step and analyze performance trades, is explained through a case study. The application presented is for a building energy retrofit, comparing building energy consumption before and after application of technologies from a set of contenders, but it can be extended to the design of new buildings.
Optimization of Electrodynamic Screens for Efficient Removal of Dust Particles
Authors: Sayyah Arash , Stark Jeremy W. , Hudelson John N. , Horenstein Mark N. , Mazumder Malay K.
Published: October 2014

Electrodynamic Screens (EDS) is a promising alternative for removing dust particles from solar collectors and advantageous compared to the current water-based cleaning methods used widely in solar industries. To operate the EDS for efficient removal of dust layer having different size distributions and compositions of particles, it is necessary to optimize the design of the EDS and the materials used for construction. Since the electric field is the main component in removal of the dust particles, this paper reports optimization of the electric field as the function of geometric parameters of the EDS. For the optimization of the EDS, two distinct objective functions have been defined and the optimal values for the electrode width and inter-electrode spacing have been provided. The EDS model has been implemented in the COMSOL Multiphysics finite element analysis (FEA) software and analytical results have been verified. Based on the optimized parameters, different designs have been gone under fabrication process and then testing. This is a work in progress paper and the experimental results will be provided later to corroborate the higher clearance rates for the optimal designs.
Comparative Study of Solar Assisted Cooling Technologies for Two Different Climates
Authors: Montero Andrés , López-Villada Jesús , Naranjo-Mendoza Carlos , Labus Jerko
Published: October 2014

This study describes the influence of climate conditions and different solar assisted absorption technologies on the energy performance of air-conditioning systems. The correlation between dynamic cooling load profile and the performance of various solar assisted absorption system configurations was analyzed for two different climates: a hot-summer Mediterranean climate (Seville, Spain) and a tropical savannah climate (Guayaquil, Ecuador). A generic two-story office building was selected as a case study. The building fabrics are set to comply with the best practices of the two countries and the building counts with a useful area of 1152 m2 for the solar system installation. The hourly cooling demand for the building was calculated by using a simplified calculation method based on degree-days with variable base temperature. Three different solar assisted absorption configurations were simulated in TRNSYS software environment based on three types of solar collectors: evacuated tube collectors, parabolic trough collectors and linear Fresnel collectors (micro-concentrator type). The first configuration which involves evacuated tube collectors was coupled to a single-effect H2O-LiBr absorption chiller, while the other two configurations include double-effect H2O-LiBr absorption chiller. Models of two different absorption chillers were developed based on the characteristic equation method (ΔΔt). The comparison between the configurations was based on the primary energy analysis and CO2 emission.
Self-Cleaning Solar Mirrors Using Electrodynamic Dust Shield: Prospects and Progress
Authors: Mazumder Malay K. , Horenstein Mark N. , Stark Jeremy W. , Hudelson John N. , Sayyah Arash , Joglekar Nitin , Yellowhair Julius , Botts Adam
Published: October 2014

Parabolic trough and power tower technologies provide inherent advantage of thermal energy storage and high efficiency of the Concentrating Solar Power (CSP) systems for utility scale solar plants. High efficiency CSP power generation with minimal water use is one of the SunShot goals of the US Department of Energy. The specular reflectance efficiency of the solar mirrors plays a critical role in the efficiency of power generation. The optical surface of the mirrors and the receiver must be kept clean for efficient operation of the plant. Some environmental challenges in operating the large-scale CSP plants at high reflectance efficiency arise from high concentration of atmospheric dust, wind speed and variation of relative humidity (RH) over a wide range. Deposited dust and other contaminant particles, such as soot, salt, and organic particulate matters attenuate solar radiation by scattering and absorption. Adhesion of these particles on the mirror surface depends strongly by their composition and the moisture content in the atmosphere. Presence of soluble inorganic and organic salts cause corrosion of the mirror unless the contaminants are cleaned frequently.

In this paper, we briefly review (1) source of atmospheric dust and mechanisms involved in degradation of mirrors caused by salt particles, (2) loss of specular reflection efficiency as a function of particle size distribution and composition, and (3) an emerging technology for removing dust layer by using thin transparent electrodynamic screen (EDS). Feasibility of integration of EDS on the front surface of the solar collectors has been established to provide active self-cleaning properties for parabolic trough and heliostat reflectors.

Prototype EDS-integrated solar collectors including second-surface glass mirrors, metallized acrylic film mirrors, and dielectric mirrors, were produced and tested in an environmental test chambers simulating desert atmospheres. The test results show that frequent removal of dust layer can maintain the specular reflectivity of the mirrors above 90% under dust deposition at a rate ranging from 0 to 10 g/m2, with particle size varying from 1 to 50 μm in diameter. The energy required for removing the dust layer from the solar was less than 10 Wh/m2 per cleaning cycle. EDS based cleaning could therefore be automated and performed as frequently as needed to maintain reflection efficiency above 90% and thus reducing water usage for cleaning mirrors in the solar field. A comparative cost analysis was performed between EDS and deluge water based cleaning that shows the EDS method is commercially viable and would meet water conservation needs.
Experimental Study of Subcritical Water Liquefaction of Biomass: Effects of Catalyst and Biomass Species
Authors: Zhu Zhe , Toor Saqib Sohail , Rosendahl Lasse , Yu Donghong , Chen Guanyi
Published: October 2014

In this work, hydrothermal liquefaction (HTL) of wood industry residues (wood, bark, sawdust) and macroalgae for producing biofuels has been investigated under subcritical water conditions (at temperature of 300 °C), with and without the presence of a catalyst. The effects of catalyst and biomass type (woody and non-woody) on the biomass conversion, bio-crude yield, and the qualities of products were studied. The results suggested that the addition of potassium carbonate as a catalyst showed a positive effect on bio-crude yield, especially for wood, where it was enhanced to 47.48 wt%. Macroalgae showed a higher biomass conversion and a lower bio-crude yield than other woody biomass investigated in the present study, irrespective of whether the catalyst was used. Meanwhile, the effect of catalyst on macroalgae was less significant than that of woody biomass. The heating values and thermal stability of all bio-crudes were analyzed. The results showed that the higher heating values (HHVs) were in the range of 24.15 to 31.79 MJ/kg, and they were enhanced in the presence of a catalyst, except for that of the macroalgae. The solid residues were characterized by heating value, SEM and FTIR. It was found that the addition of K2CO3 lowered the solids quality in terms of the heating values, while it did not have apparent effect on the functional groups of solid residues. SEM analysis of the raw biomass and solid residues revealed that the char formation for wood, sawdust and macroalgae had initially finished when they were treated in hot compressed water at 300 °C, while conversion of bark had not completed yet.
Effect of respiratory motion on internal radiation dosimetry
Authors: Xie Tianwu , Zaidi Habib
Published: October 2014

Purpose:

Estimation of the radiation dose to internal organs is essential for the assessment of radiation risks and benefits to patients undergoing diagnostic and therapeutic nuclear medicine procedures including PET. Respiratory motion induces notable internal organ displacement, which influences the absorbed dose for external exposure to radiation. However, to their knowledge, the effect of respiratory motion on internal radiation dosimetry has never been reported before.

Methods:

Thirteen computational models representing the adult male at different respiratory phases corresponding to the normal respiratory cycle were generated from the 4D dynamic XCAT phantom. Monte Carlo calculations were performed using the mcnp transport code to estimate the specific absorbed fractions (SAFs) of monoenergetic photons/electrons, the S‐values of common positron‐emitting radionuclides (C‐11, N‐13, O‐15, F‐18, Cu‐64, Ga‐68, Rb‐82, Y‐86, and I‐124), and the absorbed dose of 18F‐fluorodeoxyglucose (18F‐FDG) in 28 target regions for both the static (average of dynamic frames) and dynamic phantoms.

Results:

The self‐absorbed dose for most organs/tissues is only slightly influenced by respiratory motion. However, for the lung, the self‐absorbed SAF is about 11.5% higher at the peak exhale phase than the peak inhale phase for photon energies above 50 keV. The cross‐absorbed dose is obviously affected by respiratory motion for many combinations of source‐target pairs. The cross‐absorbed S‐values for the heart contents irradiating the lung are about 7.5% higher in the peak exhale phase than the peak inhale phase for different positron‐emitting radionuclides. For 18F‐FDG, organ absorbed doses are less influenced by respiratory motion.

Conclusions:

Respiration‐induced volume variations of the lungs and the repositioning of internal organs affect the self‐absorbed dose of the lungs and cross‐absorbed dose between organs in internal radiation dosimetry. The dynamic anatomical model provides more accurate internal radiation dosimetry estimates for the lungs and abdominal organs based on realistic modeling of respiratory motion. This work also contributes to a better understanding of model‐induced uncertainties in internal radiation dosimetry.
Physics of the granite sphere fountain
Authors: Snoeijer Jacco H. , der Weele Ko van
Published: October 2014

A striking example of levitation is encountered in the “kugel fountain” where a granite sphere, sometimes weighing over a ton, is kept aloft by a thin film of flowing water. In this paper, we explain the working principle behind this levitation. We show that the fountain can be viewed as a giant ball bearing and thus forms a prime example of lubrication theory. It is demonstrated how the viscosity and flow rate of the fluid determine (i) the remarkably small thickness of the film supporting the sphere and (ii) the surprisingly long time it takes for rotations to damp out. The theoretical results compare well with measurements on a fountain holding a granite sphere of one meter in diameter. We close by discussing several related cases of levitation by lubrication.
Irreversibility in an ideal fluid
Authors: Jenkins Alejandro
Published: October 2014

When a real fluid is expelled quickly from a tube, it forms a jet separated from the surrounding fluid by a thin, turbulent layer. On the other hand, when the same fluid is sucked into the tube, it enters from all directions, forming a sink-like flow. We show that, even for the ideal flow described by the time-reversible Euler equation, an experimenter who only controls the pressure in a pump attached to the tube would see jets form in one direction exclusively. The asymmetry between outflow and inflow therefore does not depend on viscous dissipation, but rather on the experimenter's limited control of initial and boundary conditions. This illustrates, in a rather different context from the usual one of thermal physics, how irreversibility may arise in systems whose microscopic dynamics are fully reversible.
Implementing a simple vectorial bridge with a digital oscilloscope
Authors: Bartiromo Rosario , De Vincenzi Mario
Published: October 2014

We show how to exploit instrumentation available in undergraduate student laboratories to build a simple vectorial bridge. In particular, we take advantage of the ability to read data from a digital oscilloscope with a personal computer and describe an algorithm to obtain an accurate evaluation of the phase difference between two sinusoidal signals. The use of the bridge to characterize components of a high-Q RLC filter is shown to greatly improve the understanding of results in electrical resonance experiments. Direct evidence of dielectric losses, skin currents, and the effect of distributed capacitance is obtained.
Perturbation approximation for orbits in axially symmetric funnels
Authors: Nauenberg Michael
Published: October 2014

A perturbation method that can be traced back to Isaac Newton is applied to obtain approximate analytic solutions for objects sliding in axially symmetric funnels in near circular orbits. Some experimental observations are presented for balls rolling in inverted cones with different opening angles, and in a funnel with a hyperbolic surface that approximately simulates the gravitational force.
Conditional density-based analysis of T cell signaling in single-cell data
Authors: Krishnaswamy Smita , Spitzer Matthew H. , Mingueneau Michael , Bendall Sean C. , Litvin Oren , Stone Erica , Pe’er Dana , Nolan Garry P.
Published: October 2014

Cellular circuits sense the environment, process signals, and compute decisions using networks of interacting proteins. To model such a system, the abundance of each activated protein species can be described as a stochastic function of the abundance of other proteins. High-dimensional single-cell technologies, such as mass cytometry, offer an opportunity to characterize signaling circuit-wide. However, the challenge of developing and applying computational approaches to interpret such complex data remains. Here, we developed computational methods, based on established statistical concepts, to characterize signaling network relationships by quantifying the strengths of network edges and deriving signaling response functions. In comparing signaling between naïve and antigen-exposed CD4
+
T lymphocytes, we find that although these two cell subtypes had similarly wired networks, naïve cells transmitted more information along a key signaling cascade than did antigen-exposed cells. We validated our characterization on mice lacking the extracellular-regulated mitogen-activated protein kinase (MAPK) ERK2, which showed stronger influence of pERK on pS6 (phosphorylated-ribosomal protein S6), in naïve cells as compared with antigen-exposed cells, as predicted. We demonstrate that by using cell-to-cell variation inherent in single-cell data, we can derive response functions underlying molecular circuits and drive the understanding of how cells process signals.
The structure of interfacial water on gold electrodes studied by x-ray absorption spectroscopy
Authors: Velasco-Velez Juan-Jesus , Wu Cheng Hao , Pascal Tod A. , Wan Liwen F. , Guo Jinghua , Prendergast David , Salmeron Miquel
Published: October 2014

The molecular structure of the electrical double layer determines the chemistry in all electrochemical processes. Using x-ray absorption spectroscopy (XAS), we probed the structure of water near gold electrodes and its bias dependence. Electron yield XAS detected at the gold electrode revealed that the interfacial water molecules have a different structure from those in the bulk. First principles calculations revealed that ~50% of the molecules lie flat on the surface with saturated hydrogen bonds and another substantial fraction with broken hydrogen bonds that do not contribute to the XAS spectrum because their core-excited states are delocalized by coupling with the gold substrate. At negative bias, the population of flat-lying molecules with broken hydrogen bonds increases, producing a spectrum similar to that of bulk water.
First Genome Sequence of Potential Mycotoxin-Degrading Bacterium
Devosia nanyangense
DDB001
Authors: Onyango Mark , Wang Yang , Nickel Ole , Zhao Chen , Zhang Xiaolin , Hartke Axel , Hemberger Juergen , Cemic Franz
Published: October 2014

Devosia
sp. nov. DDB001, isolated from mycotoxin-contaminated soil, is a potential mycotoxin-degrading alphaproteobacterium. To our knowledge, this is the first draft genome announcement of a
Devosia
species.
First Genome Sequence of a Canine Distemper Virus Strain from South America
Authors: Sarute Nicolás , Delgado María V. , Carrau Lucía , Benech Alejandro , Francia Lourdes , Pérez Ruben , Panzera Yanina
Published: October 2014

Canine distemper virus causes a severe infectious disease in carnivores worldwide. Herein, we sequenced and analyzed the genome of a new strain (Uy251/2012) isolated from a dog in Uruguay. The Uy251/2012 strain belongs to the Europe1/South America1 lineage, and constitutes the first report of a genomic sequence in South America.
Whole-Genome
Yersinia
sp. Assemblies from 10 Diverse Strains
Authors: Daligault H. E. , Davenport K. W. , Minogue T. D. , Bishop-Lilly K. A. , Broomall S. M. , Bruce D. C. , Chain P. S. , Coyne S. R. , Frey K. G. , Gibbons H. S. , Jaissle J. , Koroleva G. I. , Ladner J. T. , Lo C.-C. , Munk C. , Palacios G. F. , Redden C. L. , Rosenzweig C. N. , Scholz M. B. , Johnson S. L.
Published: October 2014

Yersinia
spp. are animal pathogens, some of which cause human disease. We sequenced 10
Yersinia
isolates (from six species:
Yersinia enterocolitica
,
Y. fredericksenii
,
Y. kristensenii
,
Y. pestis
,
Y. pseudotuberculosis
, and
Y. ruckeri
) to high-quality draft or complete status. The genomes range in size from 3.77 to 4.94 Mbp.
Complete Genome Sequence of the Oral Spirochete Bacterium Treponema putidum Strain OMZ 758
T
(ATCC 700334
T
)
Authors: Lacap-Bugler Donnabella C. , Jiang Jingwei , Huo Yong-Biao , Chan Yuki , Leung Frederick C. , Watt Rory M.
Published: October 2014

The oral spirochete bacterium
Treponema putidum
inhabits human periodontal niches. The complete genome sequence of the OMZ 758
T
(ATCC 700334
T
) strain of this species was determined, revealing a 2,796,913-bp chromosome, with a G+C content of 37.30% and a single plasmid (pTPu1; 3,649 bp) identical to pTS1 from
Treponema denticola
.
Complete Genome Sequence of Salmonella enterica subsp.
enterica
Serovar Enteritidis Strain SEJ
Authors: Bishop-Lilly K. A. , Frey K. G. , Daligault H. E. , Davenport K. W. , Bruce D. C. , Chain P. S. , Coyne S. R. , Chertkov O. , Freitas T. , Jaissle J. , Koroleva G. I. , Ladner J. T. , Minogue T. D. , Palacios G. F. , Redden C. L. , Xu Y. , Johnson S. L.
Published: October 2014

Salmonella enterica
constitutes a group of enteric pathogens with a broad host range, including humans, reptiles, and birds.
S. enterica
subsp.
enterica
is a common cause of inflammatory diarrhea in humans. We present the draft genome of
S. enterica
subsp.
enterica
serovar Enteritidis strain SEJ, including a 59-kbp plasmid.
Draft Genome Sequence of Geobacillus icigianus Strain G1w1
T
Isolated from Hot Springs in the Valley of Geysers, Kamchatka (Russian Federation)
Authors: Bryanskaya Alla V. , Rozanov Aleksey S. , Logacheva Maria D. , Kotenko Anastasia V. , Peltek Sergey E.
Published: October 2014

The
Geobacillus icigianus
G1w1
T
strain was isolated from sludge samples of unnamed vaporing hydrothermal (97°С) outlets situated in a geyser in the Troinoy region (Valley of Geysers, Kronotsky Nature Reserve, Kamchatka, Russian Federation; 54°25′51.40″N, 160°7′41.40″E). The sequenced and annotated genome is 3,457,810 bp and encodes 3,342 genes.
Gv20-Based Acupuncture for Animal Models of Acute Intracerebral Haemorrhage: A Preclinical Systematic Review and Meta-Analysis
Authors: Li Hui-qin , Li Ji-huang , Liu Ai-ju , Ye Mai-yun , Zheng Guo-qing
Published: October 2014

Background

Spontaneous intracerebral haemorrhage (ICH) is the most devastating subtype of stroke, but there is currently no evidence-based treatment strategy. Acupuncture is a well-known traditional Chinese therapy for stroke-induced disability, and GV20 is the commonly used acupuncture point.

Objective

To evaluate the efficacy of GV20-based acupuncture in animal models of acute ICH.

Methods

Studies of GV20-based acupuncture in animal models of acute ICH were identified from six databases up to July 2013. Study quality for each included article was evaluated according to the CAMARADES 10-item checklist. Outcome measures were neurological deficit scores and brain water content. All the data were analysed using RevMan V.5.1 software.

Results

Nineteen studies were identified describing procedures involving 1628 animals. The quality score of the studies ranged from 3 to 6, with a mean of 4.6. The global estimate of the effect of GV20-based acupuncture was 0.19 (95% CI 0.13 to 0.25, p<0.001) SDs improvement in outcome compared with controls. In subgroup analyses, size of effect was higher where the outcome was measured as the neurological deficit score than the brain water content or both (p<0.001).

Conclusions

These findings show the possible efficacy of GV20-based acupuncture in animal models of acute ICH, suggesting it as a candidate therapy for acute ICH.