bluuebunny/crossref_metadata_2025 huggingface dataset:
A 1 MWe Low-NOx Portable Biomass-Burning Back-Heated Engine Incorporating On-Demand Fuel Processing and Solid Fuel Combustion
Authors: Sullivan Shaun D. , Kesseli James
Published: October 2014

Contemporary biomass-burning power systems face a number of economic constraints that have historically limited their broad adoption. Foremost among these is the cost of transporting the biomass fuel within the collection radius required to sustain the system. Many systems capable of using raw feedstocks incorporate Rankine power cycles, which are not economical in plants below 50 MWe. At this scale the collection radius becomes prohibitively large with respect to transportation costs. An alternative solution has been to transport feedstock to a processing facility where the fuel can be densified into a bio-oil. The high capital and labor costs associated with the processing facility make the fuel cost too high for electric power production. The solution presented here is a Brayton cycle system that incorporates several innovations to address the historical limitations to biomass energy production, while retaining the traditional advantages. These advantages include low operating and maintenance (O&M) costs, autonomous operation, portability, and fast starting. The relatively small size of the 1 MWe engine reduces the required feedstock collection radius to a range that is economical and practical. The engine incorporates a novel compact solid-fuel-burning combustor that is designed to emulate traditional gas-turbine can-type combustor behavior and performance, enabling the use of a broad range of biomass feedstocks. Integrated on-demand fuel processing eliminates the need for an expensive central facility and serves to dry, densify, and pulverize the feedstock for direct injection into the cycle. Additionally, bound nitrogen within the fuel is driven off as stable elemental nitrogen during the integrated fuel-processing, allowing combustion to occur with characteristically low emissions. The engine itself is designed for maximum efficiency in a back-heated configuration, wherein the cycle heat addition takes place downstream of the turbine. This arrangement protects the turbomachinery and bearings from the risk of foreign object damage (FOD) or contamination that might potentially be introduced by the variable feedstock. An overview of the full design is presented, including thermodynamic cycle models and conversion efficiencies. An operational profile is provided, including the collection radius and transportation costs associated with the solution. Test data for a scale solid biomass combustor, including emissions results, is presented.
Transport Energy Demand Modeling of the United States Using Artificial Neural Networks and Multiple Linear Regressions
Authors: Kialashaki Arash , Reisel John
Published: October 2014

In 2009, the transportation sector was the second largest consumer of primary energy in the United States, following the electric power sector and followed by the industrial, residential, and commercial sectors. The pattern of energy use varies by sector. For example, petroleum provides 96% of the energy used for transportation but its share is much less in other sectors. While the United States consumes vast quantities of energy, it has also pledged to cut its greenhouse gas emissions by 2050. In order to assist in planning for future energy needs, the purpose of this study is to develop a model for transport energy demand that incorporates past trends.

This paper describes the development of two types of transportation energy models which are able to predict the United States’ future transportation energy-demand. One model uses an artificial neural network technique (a feed-forward multilayer perceptron neural network coupled with back-propagation technique), and the other model uses a multiple linear regression technique. Various independent variables (including GDP, population, oil price, and number of vehicles) are tested.

The future transport energy demand can then be forecast based on the application of the growth rate of effective parameters on the models. The future trends of independent variables have been predicted based on the historical data from 1980 using a regression method. Using the forecast of independent variables, the energy demand has been forecasted for period of 2010 to 2030.

In terms of the forecasts generated, the models show two different trends despite their performances being at the same level during the model-test period. Although, the results from the regression models show a uniform increase with different slopes corresponding to different models for energy demand in the near future, the results from ANN express no significant change in demand in same time frame. Increased sensitivity of the ANN models to the recent fluctuations caused by the economic recession may be the reason for the differences with the regression models which predict based on the total long-term trends.

Although a small increase in the energy demand in the transportation sector of the United States has been predicted by the models, additional factors need to be considered regarding future energy policy. For example, the United States may choose to reduce energy consumption in order to reduce CO2 emissions and meet its national and international commitments, or large increases in fuel efficiency may reduce petroleum demand.
Numerical Analysis of Total Energy Storage of Nanofluidized Heat Transfer Fluid in Thermocline Thermal Energy Storage System
Authors: Hossain Nazmul , Afrin Samia , Ortega Jesus D. , Kumar Vinod , Banerjee Debjyoti
Published: October 2014

Thermal energy storage (TES), when combined with a concentrating solar power (CSP) plant has potential to produce electricity at a cost-competitive rate to traditional sources of electricity production. In single tank TES system both the hot fluid and cold fluid settle in the same tank. The region of contact of these two fluids is called thermocline. Preservation of this thermocline region in the cylindrical tank during charging and discharging cycles depends on the uniformity of the velocity profile at any horizontal plane. So to maintain this thermocline region, a pipe flow distributor was placed near the inlet and outlet of the cylindrical tank. To optimize the efficiency of this single tank TES system is to increase the thermo-physical properties of heat transfer fluid. This addition will result in harnessing solar energy by increasing thermal efficiency of the thermodynamic cycles. Adding of nanoparticles, in the heat transfer fluid give rise of this thermo-physical properties i.e. thermal conductivity (k) and specific heat capacity (Cp). Hitec® molten salt is used as the base-fluid and synthesized with five different types of nanoparticles (SiO2, Al2O3, Fe3O4, ZnO and Ag) with different concentrations. The values of effective k and Cp are calculated for the new Hitec® nanofluid. The doping of nano-particles results in higher k and Cp when compared to the base fluid. Higher Cp is expected to improve the thermal storage capacity but higher value of k is expected to increase the thermal diffusivity, thereby affecting the performance of the thermocline. The diffusivity depends on the ratio of k to Cp and density of the effective properties. So there is a need to balance the effective properties to improve thermal storage performance. The total energy storage capacity is then checked by finite volume based computational fluid dynamics software. The simulation shows how the performance of the nanofluid changes at different concentrations in a single tank TES system during its charging-discharging cycle.
Systematic Selection and Siting of Vehicle Fueling Infrastructure to Synergistically Meet Future Demands for Alternative Fuels
Authors: Willette Peter J. , Samuelsen G. Scott , Shaffer Brendan
Published: October 2014

In order to meet the increasing demand for low carbon and renewable transportation fuels, a methodology for systematically establishing build-out scenarios is desirable. In an effort to minimize initial investment costs associated with the development of fueling infrastructure, the Analytical Hierarch Process (AHP) has been developed and applied, as an illustration, to the case of hydrogen fueling infrastructure deployment in the State of California. In this study, five parameters are selected in order to rank hydrogen transportation fuel generation locations within the State. The weighting parameters include: 1) Proximity to Power Generation Facilities, 2) Lowest Land Cost, 3) Least Populous, 4) Proximity to Existing Energy Infrastructure, and 5) Water Infrastructure Proximity. These parameters are selected to maximize land availability and minimize cost. In order to utilize meaningful weighting factors within the AHP, expert inputs were gathered and employed in the exercising of the models suite of weighting parameters. The analysis uses statewide geographic information obtained from the California Energy Commission and identifies both key energy infrastructure expansion locations and critical criteria that make the largest impact in the location of selected sites.
The 2013 University of Nevada Las Vegas Solar Decathlon House: Strategy, Design, Simulation and Results
Authors: Zeng Zheng , Hurt Rick , Boehm Robert F.
Published: October 2014

The U.S. Department of Energy (DOE) has posed the challenge to the homebuilding industry to make available cost-effective net-zero energy homes for all Americans by 2030. University of Nevada Las Vegas’s DesertSol was the 2nd place winner in the U.S. Department of Energy Solar Decathlon 2013. This paper identifies the implementation of integrative design during the planning and programming phases of the project, and the ways such practice benefited the team and the contractors. This paper also describes the unique approaches and simulation methods for the whole building design. The team designed a high performance whole building system that dramatically reduced the overall energy loads through careful detailing of the entire building envelope, efficient equipment and lighting, and onsite renewable generation with both solar photovoltaic (PV) and solar thermal systems. Building Information Management (BIM) software was used collaboratively and iteratively among the multi-discipline team throughout the 2 year research, design and build phases. Furthermore, this paper also discusses the optimization of project cost and affordability versus building performance criteria. Each individual system was modeled using specific software or developed codes. NREL’s BEopt was used for identifying the cost-optimal packages for the whole building energy analysis, by inputting discrete parametric options, reflecting realistic construction materials and practices. Data collected during the Solar Decathlon event was a validation that the systems were functional and performed as simulated. Continuing data monitoring of the home at its permanent Las Vegas location will validate the modeled long-term performance of this house.
Review of Flow Patterns in a Column Reactor for Photobioreactor Application
Authors: Anderson Gary A. , Kommareddy Anil , Suess Taylor , Gent Stephen P.
Published: October 2014

Photobioreactors (PBRs) and chemical reactors are often vertical columns with either circular or rectangular cross sections. The reactors are frequently referred to as column reactors and are treated as if they perform in the same manner. The reactors can have two different types of flow established in them regardless of cross sectional shape depending on the saprger/diffuser type and location within the reactor. The flow patterns in the reactors are induced by gas that is bubbled into the reactor volume usually near the bottom of the reactor. When the gas bubbles rise up through the reactor in a plug flow fashion, most of the mixing is in the radial direction which tends to make the reactor liquid and gas more homogeneous across the width of the reactor. The gas bubbles in the reactor may not move up through the reactor in a plug flow fashion, but may instead move vertically up through a portion of the reactor cross-section. This will establish a column of bubbles and liquid rising from the bottom of the reactor up to the surface and, in turn, induce a column(s) of liquid moving downward from the top of the reactor to the bottom. This behavior is similar to an air lift reactor which generally has walls physically dividing the upward (riser) and downward (down comer) flows. Without physical separation of the flows, the percent of cross sectional area of the reactor acting as the riser and down comer is established by the gas flow rate through the reactor, reactor cross sectional area, and the reactor volume. Velocity of flow(s) in the reactors is often based on the superficial gas velocity, which is the incoming gas flow rate divided by the gross cross sectional area of the reactor volume. This parameter may not relate to the two flows in the same manner. The two different flow patterns will be discussed in relation to superficial gas velocity, light in a PBR, chemical reactions in the reactor, and riser and down comer size.
Optical Properties of Select Particulates After High-Temperature Exposure
Authors: Roop Jonathan , Jeter Sheldon , Abdel-Khalik Said I. , Ho Clifford K.
Published: October 2014

One increasingly viable option for high temperature concentrator solar power (CSP) is a central receiver system with a particle heating receiver (PHR). A PHR system uses suitable particulates to capture and store energy. It is expected that the particles will be sustained at high temperatures (in the range of 300°C or 400°C to 700°C or 800°C or even 1000°C) on most typical days of plant operation, so there is interest in how the particle optical properties might change after prolonged high-temperature exposure.

This paper presents the results from experiments conducted over a 5-month period in which samples of various types of particulates including silica sands and alumina proppants were exposed to high temperatures for extended periods of time. The reflectance of a bed of particles was measured at room temperature in 8 wavelength bands using the 410-Solar reflectometer device developed by Surface Optics Corporation. The infrared emittance was determined using the ETS-100 emissometer instrument, also developed by Surface Optics Corporation [1,2].

Particles were heated to 950°C and 350°C, and measurements were recorded at intervals during the exposure so that trends in the optical properties over time could be observed. From the measured data, the total solar absorptance and total hemispherical emittance at high temperature were computed; these results are also presented.
Study of Combustion Characteristics of Ethanol at Different Dilution With the Carrier Gas
Authors: Imteyaz Binash , Habib Mohamed A.
Published: October 2014

With the ever rising concern of global warming, carbon capture is gaining the reputation of one of the most challenging fields of research. A very promising technology to capture CO2 is oxy-combustion. Oxy-combustion offers several advantages over conventional combustion technologies, such as flue gas volume reduction, high combustion efficiency, low fuel consumption and significant reduction in NOx emissions. Liquid fuel is available and it is the most widely used source of energy in the world. Easy handling and transportation, less storage volume and higher flame temperature are some of the features of liquid fuel which give it an upper hand over other sources. In this study, an experimental work on oxygen enriched combustion of ethanol in a vertical reactor by Lacas F. et. al. has been modeled numerically. Non-premixed model using Probability Density Function has been incorporated to simulate the combustion process of ethanol droplets. Predicted combustion characteristics are found to be in good compliance with the experimental data. In addition to this, effects of dilution of carbon-dioxide in oxygen on the flame properties have also been presented. Combustion of ethanol in oxygen-carbon dioxide environment has been compared with that of the conventional air environment.
Film Cooling of Turbine Blade Surface With Extended Exit Holes
Authors: Forghan Fariborz , Askari Omid , Narusawa Uichiro , Metghalchi Hameed
Published: October 2014

The main goal of gas turbine design is the effective use of energy. Usually, the efficient high temperature first and second stage turbine blade surface is cooled by jet of coolant flow from extended exit holes (EEH). Against the prevailing hot gas flow, the flow through EEH must be designed to form a film of cool air over the blade. Computational analyses are performed to examine the cooling effectiveness of flow from EEH over the suction side of a blade by solving conservation equations (mass, momentum and energy) and the ideal gas equation of state for the three-dimensional, turbulent, compressible flow. A diverging flow through EEH is typically choked at its throat, resulting in a supersonic flow, a shock and then a subsonic flow downstream. The location of the shock relative to the high-temperature gas flow over the blade determines the temperature distribution along the blade surface; which is analyzed in detail when the coolant flow rate is varied.
An Intelligent On-Off Regulation Method by Predicting the Valve On-Time Ratio in District Heating
Authors: Liu Lanbin , Ma Yufei
Published: October 2014

Good room temperature control is beneficial for user thermal comfort and health. It also helps reduce energy consumption and carbon dioxide emissions inside the buildings. However, there are certain limitations with the current thermostatic valves commonly used in central heating systems, especially the ones used in China, since they cannot satisfactorily adjust room temperatures. In response to such problems, an intelligent on-off regulation method is presented in this paper. The room temperature can be maintained by controlling the valves according to the on-time ratio predicted by this method. The on-time ratio is predicted for each cycle, and the current ratio is decided by checking a 6-order fuzzy-control table with room temperature deviations in the last step, as well as room temperature set points. The design of the fuzzy-control table as a major factor that may affect the controlling effect is also discussed. A proper controlling cycle and optimal controlling table have been worked out. Finally, this paper discusses the application effectiveness of this strategy. Results show that the room temperature can be maintained in the range of set point ±0.5°C using this method in different conditions. It is fair to say that this method is a stable, reliable and advanced controlling method with accurate control.
Development of High Temperature Liquid Metal Heat Transfer Fluids for CSP Applications
Authors: Warrier Gopinath R. , Ju Y. Sungtaek , Schroers Jan , Asta Mark , Hosemann Peter
Published: October 2014

In response to the DOE Sunshot Initiative to develop low-cost, high efficiency CSP systems, UCLA is leading a multi-university research effort to develop new high temperature heat transfer fluids capable of stable operation at 800°C and above. Due to their operating temperature range, desirable heat transfer properties and very low vapor pressure, liquid metals were chosen as the heat transfer fluid. An overview of the ongoing research effort is presented.

Development of new liquid metal coolants begins with identification of suitable candidate metals and their alloys. Initial selection of candidate metals was based on such parameters as melting temperature, cost, toxicity, stability/reactivity Combinatorial sputtering of the down selected candidate metals is used to fabricate large compositional spaces (∼ 800), which are then characterized using high-throughput techniques (e.g., X-ray diffraction). Massively parallel optical methods are used to determine melting temperatures. Thermochemical modeling is also performed concurrently to compliment the experimental efforts and identify candidate multicomponent alloy systems that best match the targeted properties. The modeling effort makes use of available thermodynamic databases, the computational thermodynamic CALPHAD framework and molecular-dynamics simulations of molten alloys. Refinement of available thermodynamics models are performed by comparison with available experimental data. Characterizing corrosion in structural materials such as steels, when using liquid metals, and strategies to mitigate them are an integral part of this study. The corrosion mitigation strategy we have adopted is based on the formation of stable oxide layers on the structural metal surface which prevents further corrosion. As such oxygen control is crucial in such liquid metal systems. Liquid metal enhanced creep and embrittlement in commonly used structural materials are also being investigated. Experiments with oxygen control are ongoing to evaluate what structural materials can be used with liquid metals. Characterization of the heat transfer during forced flow is another key component of the study. Both experiments and modeling efforts have been initiated. Key results from experiments and modeling performed over the last year are highlighted and discussed.
Ground Cooling System for Improving the Efficiency of Low Temperature Power Generation
Authors: Vidhi Rachana , Garg Pardeep , Orosz Matthew S. , Goswami D. Yogi , Kumar Pramod
Published: October 2014

This paper presents an analysis of an organic Rankine cycle (ORC) with dry cooling system aided by an earth-coupled passive cooling system. Several organic fluids were considered as working fluids in the ORC in the temperature range of 125–200°C. An earth-air-heat-exchanger (EAHE) is studied for a location in the United States (Las Vegas) and another in India (New Delhi), to pre cool the ambient air before entering an air-cooled condenser (ACC). It was observed that the efficiency of the system improved by 1–3% for the system located in Las Vegas and fluctuations associated with temperature variations of the ambient air were also reduced when the EAHE system was used. A ground-coupled heat pump (GCHP) is also studied for these locations where cooling water is pre cooled in an underground buried pipe before entering a condenser heat exchanger in a closed loop. The area of the buried pipe and the condenser size are calculated per kW of power generation for various working fluids.
Experimental Evaluation of a Water Source CO2 Heat Pump Incorporating Novel Gas-Cooler Configuration
Authors: Murray Portia , Harrison Stephen , Johnson Gary , Stinson Ben
Published: October 2014

Carbon dioxide’s use as an alternative refrigerant has been increasing in popularity due to its low global warming and ozone depletion potentials. In recent years, a number of companies and researchers have investigated applications of CO2 heat pumps for water heating.

This study investigates the experimental testing of a CO2 heat pump water heater (HPWH) at Queen’s University. For the tests, the conventional factory gas-cooler on an Eco-cute unit and air-source evaporator was replaced with a specially designed brazed-plate gas-cooler. It rejected heat to a 273 litre hot water and the evaporator sourced heat from a warm water supply.

Experiments were conducted using both forced and natural convection (i.e., thermosyphon) flow between the gas-cooler and hot water tank. Thermosyphon flow was studied to evaluate its effects on storage tank stratification and heat pump operation (i.e., coefficient of performance). Results were compared to forced circulation cases run over a range of flow rates.

In the forced convection flow test, it was observed that a decrease in gas-cooler average water temperature increased the coefficient of performance (COP) non-linearly and an increase in the water-side flow rate increased the COP and the effectiveness of the gas-cooler.

The thermosyphon had an average flow rate of 0.75 L/min and an average COP of 3.1. Thermosyphon flow kept the hot water tank fully stratified until fully charged. Water was delivered at an average of 70°C. It was also observed that thermosyphon flow rate depended on the state of charge (i.e., temperature distribution) in the storage tank.

In order to increase the performance, a gas-cooler with a lower pressure drop should be used to increase the thermosyphon flow rate.
Delivering Renewable Integration Services Through University Microgrid Operations: A University of California, San Diego Microgrid Case Study
Authors: Sreedharan Priya , Farbes Jamil , Cutter Eric
Published: October 2014

Integrating high penetration variable renewables in economically and operationally plausible ways is a current clean energy challenge facing many countries and regions, including California. Renewable energy deployment is a relevant pathway to decarbonize the electricity sector and reduce greenhouse gas emissions (GHGs) and mitigate the harmful effects of climate change. This paper highlights the key findings from a recently completed study, funded by the California Solar Initiative, to develop and investigate strategies to integrate high penetration renewable energy and solar photovoltaic (PV) systems using distributed energy resources (DER). We develop hypothetical operating strategies that utilize the DER present in campus microgrids, such as combined heat and power (CHP) systems and thermal energy storage, and evaluate these based on economic criteria.

Our host site is the University of California, San Diego (UCSD) microgrid, which has a rich DER base that includes a 2.8 MW fuel cell powered by directed biogas, 30 MW of onsite generation, steam and electric chillers, thermal storage and roughly 1.5 MW of onsite solar PV. We develop and evaluate three types of strategies for integrating renewable generation: peak load shifting, on-site PV firming, and grid support. We analyze these strategies with an hourly dispatch optimization model and one year of data. We define a successful renewable integration strategy as one that is operationally plausible and economically viable.

We find all three classes of strategies are technically feasible and can be cost-effective under certain conditions. However, we find that the value proposition to customers such as the UCSD campus, under current tariff structures and market prices, will need to be higher to motivate such customers to offer these services, given the risks associated with changing microgrid operations from regular practice. Our findings suggest alternative incentive mechanisms and engagement strategies beyond those pathways currently available are needed to leverage the potential of DER at campuses for renewables integration purposes. Such efforts are relevant not only to campus resources but to similar commercial and industrial loads across California, including the vast combined heat and power resources.
Improving the Financial Performance of Concentrating Solar Thermal Power
Authors: Beath Andrew C. , Webby Brian , Meybodi Mehdi Aghaei
Published: October 2014

Commercial-scale implementation of concentrating solar thermal (CST) technologies for electricity generation has been increasing worldwide, but technology assessments produced by engineering consultancies typically indicate that electricity production using CST is more expensive than most other renewable energy technologies. A review of a selection of costing studies that have been prepared in recent years for Australian government and industry bodies suggests that electricity cost estimates for CST technologies are exaggerated by a combination of high capital cost estimates and the financial analysis methods used. The results of these assessments are often used in investment decision-making processes of industry and government bodies, so this may have a negative impact on further development of CST technologies. While it is apparent that revision of the methods used in these analyses could improve the apparent cost effectiveness of CST, it is also apparent that the competitiveness of CST technologies needs to be improved through cost reduction and generation improvement. One major driver for this is that some CST technologies have the capability to efficiently store energy in thermal form for electricity production on demand and this could have significant benefits to both specific users and to the general electricity network stability. As a stage in identifying potential targets for new research that will improve competitiveness of CST technologies, a sensitivity analysis was performed to examine the influence of a broad range of factors on the cost of electricity using combined performance modeling and financial analysis. This largely reconfirms the commonly held view that reduction of solar collector costs is a critical target, but also identifies the importance of improving the performance of the overall power generation cycle and general cost reduction throughout the plants.
Heat Transfer Performance of Twisted Heat Exchanger for Carbon Dioxide Gas in a Dispersed Power Plant System Using Marine Biomass Resource
Authors: Shibahara Makoto
Published: October 2014

This paper is to propose a basic concept of marine renewable energy power plant system as a dispersed one, which is composed of a marine biomass plantation and a micro gas turbine. In this system, high-efficiency compact heat exchanger becomes necessary for the limit of the marine plant space. The author has already reported about a steady and transient heat transfer process for CO2 flowing over a horizontal plate under wide experimental conditions assuming a plate-type heat exchanger. For the heat transfer enhancement of the heat exchanger, the twisted plates were inserted in the tube and parallel plates. In the experiment, the overall heat transfer coefficients of the heat exchanger for carbon dioxide gas (CO2) are measured to construct a fundamental database for the proposed marine renewable energy system. Moreover, the three-dimensional analysis of the twisted heat exchanger has been conducted using the commercial CFD code, CFD2000. The twisted plate with a thickness of 0.3 mm is inserted in a tube which inner diameter is 7 mm. The gas flow velocities are ranged from 2.5 to 7.18 m/s for the inlet gas temperature of 323K. In the experiment, the overall heat transfer coefficient increases as the gas flow velocity increases. In the numerical simulation, the fluid structure in the tube has been changed caused by the twisted plate. The flow velocity near the twisted plate increases due to the blockage of the flow-pass. The temperature distribution was affected by the helically twisting fluid motion.
Process and Lessons-Learned From an Interdisciplinary Collaboration in the Design and Construction of a Net-Zero Energy Solar House
Authors: Azarbayjani Mona , Cecchi Valentina , Tempest Brett
Published: October 2014

This paper reviews the development process of a net-zero-energy modular house, called UrbanEden, which was the UNC-Charlotte entry to the 2013 US Department of Energy Solar Decathlon competition. It reports the collaboration of students and faculty from various colleges and schools at UNC-Charlotte working towards delivering a net-zero energy house for the competition held in October in Irvine California.

The study presents the participation of students involved in various phases of schematic design, design development and construction. It also identifies the composition and organization of students through the two-year progress and how it evolved throughout the process. The paper also reviews the curriculum integration in school of Architecture with Engineering. The lessons learned from the process will be discussed.
High-Efficiency Thermophotovoltaic System by Quasi-Monochromatic Thermal Radiation
Authors: Kohiyama Asaka , Shimizu Makoto , Kobayashi Hiroaki , Iguchi Fumitada , Yugami Hiroo
Published: October 2014

Efficiency of solar-thermophotovoltaic (TPV) systems can be improved by controlling spectral property of thermal radiation to match the photovoltaic (PV) cells spectral response. We developed a spectrally selective emitter which can emit quasi-monochromatic thermal radiation to improve the efficiency of TPV systems. From the evaluation by the detailed-balance model for gallium antimonite (GaSb) TPV cells, the photovoltaic conversion efficiency over 50 % is achievable in the case of the emitter temperature over 1800K and emitter Q-value over 15. The numerical simulation based on Rigorous-Coupled Wave Analysis revealed that the quasi-monochromatic thermal radiation can be obtained by closed-end microcavity structure. A solar-TPV system equipped with a solar-simulator is fabricated to evaluate the effect of spectrally selective emitter. By using GaSb TPV cells and spectrally selective emitter based on dielectric layer coating, photovoltaic conversion efficiency of 26% and total efficiency of 7.7% are obtained at emitter temperature of 1654 K under 384 suns.
Production of Biogas by Anaerobic Digestion of Food Waste and Process Simulation
Authors: Baky Md. Abdullah Hil , Hassan Khan Muhammad Nazmul , Kader Md. Faisal , Chowdhury Habibullah Amin
Published: October 2014

Anaerobic Digestion is a biological process that takes place naturally when microorganisms break down organic matter in the absence of oxygen. In an enclosed chamber, controlled anaerobic digestion of organic matter produces biogas which is predominantly methane. The produced methane then can be directly used for rural cooking; or after certain conditioning, can be used in onsite power generation, heating homes or as vehicular fuel. Besides, food waste is increasingly becoming a major problem in every society imposing serious economic and environmental concerns. For this reason, many contemporary researches are emphasizing in finding sustainable solutions to recycle and produce energy from such waste. In this context, this paper aims to study and optimize the production of biogas from food waste (rice). For the experiment, an existing wet digestion biogas plant installed in Islamic University of Technology was used. The food waste (rice) for the research was collected from the cafeteria of Islamic University of Technology. Furthermore, a process simulation was performed by PROII software to estimate the methane production rate. Eventually, the simulated and experimental results were compared. The duration of the study period was 120 days. The experimental results showed that an average specific gas production of 14.4 kg-mol/hr can be obtained for 0.05 kg-mol/hr of starch loading rate. In case of the simulated results, the gas production was found to be 19.82 kg-mol/hr for the same loading rate of starch. The percentage of methane and CO2 obtained in the biogas plant was 69% and 29% respectively.
Optimization of a Combined Photovoltaic/Thermal Unit Using Computational Fluid Dynamics
Authors: Roberts Andrew , Lai Ming-Chia , Cheng Chi-Yang
Published: October 2014

The goal of this project was to develop a model for a Combined Photovoltaic/Thermal (PV/T) unit to ease in the assessment of potential changes to the unit before fabrication of actual parts. This process reduces the time to assess changes in the system; once the initial model is created changes are relatively simple. It also reduces cost incurred for actual testing by certified labs and can simulate output variations in different climate conditions, site locations and times of year. A commercially available PV/T unit was chosen for analysis, which utilizes two water channels under the photovoltaic assembly instead of the conventional sheet-and-tube design to actively cool the solar cells while also collecting thermal energy that can be used for heating water or air via a heat transfer system. The project described in this paper modeled the PV/T unit in two ways: (1) as a one-dimensional theoretical model and (2) modeling the system in ANSYS FLUENT and simulating the fluid flow, energy and radiation models using computational fluid dynamics (CFD). The baseline CFD model was correlated to published Solar Rating and Certification Corporation (SRCC) test data for pressure drop and thermal performance to gage accuracy of the model. Through a literature search of past work on similar modules and systems, several potential improvements to the unit were identified and a detailed analysis was conducted by individually adding each to the theoretical model, then comparing them to the output of the baseline model. Combinations of improvements were evaluated as well and assessed based on output improvement, technical feasibility and expected cost. The accuracy of the 1-D model was compared to the CFD model to assess the benefits gained from the added complexity of using computational fluid dynamics.
Fabrication of wafer-scale nanopatterned sapphire substrate by hybrid nanoimprint lithography
Authors: Guo Xu , Hu Jing , Zhuang Zhe , Deng Mengmeng , Wu Feixiang , Li Xie , Liu Bin , Yuan Changsheng , Ge Haixiong , Li Feng , Chen Yanfeng
Published: October 2014

A hybrid nanoimprint soft lithography (HNSL) technique was used to fabricate nanopatterned sapphire substrates (NPSSs) for light-emitting diodes (LEDs). HNSL combines the high resolution of nanoimprint lithography (NIL) and the conformal contact of soft lithography. The key component of HNSL is the hybrid mold, which consists of rigid nanopatterns with an anti-adhesion coating on an elastic poly(dimethylsiloxane) support. The mold was used to fabricate nanopatterns on a 2-in. sapphire substrate through a soft UV-NIL system with a double-layer resist, a top UV-curable layer, and an underlying PMMA layer. Nickel dot arrays were formed from the imprinted patterns through a lift-off process and used as the etching mask during the sapphire etching process due to nickel's high etching resistance. A wafer-scale circular-truncated-cone shaped NPSS was achieved by chlorine-based inductively coupled plasma etching. Typical blue LEDs with emission wavelengths of 452 nm were grown by metal-organic chemical vapor deposition on the NPSS and a flat sapphire substrate (FSS), respectively. The integral electroluminescence intensity and light output power of the NPSS LED were enhanced by 57.9% and 43.8%, respectively, compared to the FSS LED. The high uniformity in photoluminescence intensity across the entire NPSS LED wafer indicated good uniformity of nanopatterns fabricated by HNSL. Low cost and availability of the process and the ability to fabricate at the wafer scale make HNSL a promising method for production of NPSSs.
On time and space double-slit experiments
Authors: Bauer M.
Published: October 2014

Unlike the usual interference experiment with two slits separated in space, a time double-slit experiment uses the equivalent of a single slit covered by a shutter that is opened and closed and then quickly opened and closed again. Such experiments have recently been performed, providing further confirmation of wave-particle duality. In either type of experiment, the wave function beyond the slit(s) initially has two peaks that then spread and interfere. This article derives the results of these experiments in a schematic, but analytic solution of the time-dependent Schrödinger equation with appropriate initial conditions. In the space double-slit case, in addition to the transverse interference pattern, the time evolution at a fixed position exhibits an oscillating transient behavior similar to that obtained in the time double-slit experiment. Finally, the schematic model also reproduces the observed progressive visibility of the interference pattern obtained as a movable mask is displaced in front of the double-slit.
Draft Genome Sequence of the Novel Exopolysaccharide-Producing Bacterium
Altibacter lentus
Strain JLT2010
T
, Isolated from Deep Seawater of the South China Sea
Authors: Zhang Zilian , Chen Yi , Fu Yingnan , Jiao Nianzhi
Published: October 2014

Altibacter lentus
strain JLT2010
T
is the type strain of the recently identified novel genus and species of the family
Flavobacteriaceae
and was first isolated from deep seawater of the South China Sea. It can produce exopolysaccharide. Here we report the first draft genome of JLT2010
T
(3,160,033 bp, with GC content of 42.12%) and major findings from its annotation. It is the first reported genome in the genus
Altibacter
.
First Complete Genome Sequence of a Lineage III Peste des Petits Ruminants Virus
Authors: Dundon William G. , Kihu Simon M. , Settypalli T. Bharani K. , Gitao George C. , Bebora Lily C. , John Njenga M. , Oyugi Julius O. , Silber Roland , Loitsch Angelika , Diallo Adama
Published: October 2014

We report the first complete genome sequence of a lineage III peste des petits ruminants virus (KN5/2011) using RNA extracted from goat lung tissue collected in Kenya in 2011. The genome shows the highest nucleotide sequence identity with lineage II peste des petits ruminants viruses (PPRVs) (86.1 to 87.2%) and the lowest with lineage IV PPRVs (82.5 to 83.8%).
Genome Sequences of Brucella abortus and Brucella suis Strains Isolated from Bovine in Zimbabwe
Authors: Ledwaba Betty , Mafofo Joseph , van Heerden Henriette
Published: October 2014

This is a report of whole-genome sequences of a
Brucella abortus
strain and two
Brucella suis
strains isolated from bovine in Zimbabwe. These strains were selected based on their origin and data obtained when using multiplex PCR assays, then sequenced using next-generation sequencing technologies.
Complete Genome Assembly of
Corynebacterium
sp. Strain ATCC 6931
Authors: Daligault H. E. , Davenport K. W. , Minogue T. D. , Bishop-Lilly K. A. , Bruce D. C. , Chain P. S. , Coyne S. R. , Frey K. G. , Jaissle J. , Koroleva G. I. , Ladner J. T. , Li P-E. , Meincke L. , Munk A. C. , Palacios G. F. , Redden C. L. , Johnson S. L.
Published: October 2014

The genus
Corynebacterium
is best known for the pathogen
C. diphtheriae
; however, it contains mostly commensal and nonpathogenic, as well as several opportunistic, pathogens. Here, we present the 2.47-Mb scaffolded assembly of the type strain,
Corynebacterium
sp
.
ATCC 6931 (NCTC 1914), as deposited into GenBank under accession number CP008913.
Complete Genome Sequences of Two Middelburg Viruses Isolated from Arthropods in the Central African Republic
Authors: Tricou Vianney , Berthet Nicolas , Descorps-Declere Stéphane , Nakouné Emmanuel , Kazanji Mirdad
Published: October 2014

Arboviral diseases are a major threat to human and animal health today. Analysis of whole-genome sequences of decades-old arboviral strains may bring new insights into the viral evolution that might have facilitated outbreaks. Here, we report the whole-genome sequences of two Middelburg viruses isolated several decades ago in the Central African Republic.
The quantum echo of the early universe
Authors: Blasco Ana , Garay Luis J. , Martín-Benito Mercedes , Martín-Martínez Eduardo
Published: October 2014

We show that the fluctuations of quantum fields as seen by late comoving observers are significantly influenced by the history of the early Universe, and therefore they transmit information about the nature of space–time in timescales when quantum gravitational effects were non-negligible. We discuss how this may be observable even nowadays and thus used to build falsifiability tests of quantum gravity theories.
Classification of Ricci solitons on Euclidean hypersurfaces
Authors: Chen Bang-Yen , Deshmukh Sharief
Published: October 2014

A Ricci soliton (M, g, v, λ) on a Riemannian manifold (M, g) is said to have concurrent potential field if its potential field v is a concurrent vector field. Ricci solitons arisen from concurrent vector fields on Riemannian manifolds were studied recently in [Ricci solitons and concurrent vector fields, preprint (2014), arXiv:1407.2790]. The most important concurrent vector field is the position vector field on Euclidean submanifolds. In this paper we completely classify Ricci solitons on Euclidean hypersurfaces arisen from the position vector field of the hypersurfaces.
A note on Khovanov–Rozansky sl2-homology and ordinary Khovanov homology
Authors: Hughes Mark C.
Published: October 2014

In this paper we present an explicit isomorphism between Khovanov–Rozansky sl2-homology and ordinary Khovanov homology. This result was originally claimed in Khovanov and Rozansky's paper [Matrix factorizations and link homology, Fund. Math.199(1) (2008) 1–91, MR 2391017 (2010a:57011)], though the proof was never presented. The main missing detail is providing a coherent choice of signs when identifying variables in the sl2-homology. Along with the behavior of the signs and local orientations in the sl2-homology, both theories behave differently when we try to extend their definitions to virtual links, which seemed to suggest that the sl2-homology may instead correspond to a different variant of Khovanov homology. In this paper we describe both theories and prove that they are in fact isomorphic by showing that a coherent choice of signs can be made. In doing so we emphasize the interpretation of the sl2-complex as a cube of resolutions.
Variable Structure Control Strategy Research on Regenerative Braking for a Brushless DC Motor Driven Electric Bus Cruising Downhill
Authors: Zhao Guo-Zhu , Peng Xing
Published: October 2014

To use regenerative braking to act as an auxiliary brake to maintain the constant speed of a brushless DC motor driven electric bus (BDCMEB) on downhill based on the feature of double-loop control structure of the control method for electric vehicle traction motor and the variable structural characteristics of PWM Control System for brushless DC Motor. A double-manifold variable structure control method to control regenerative braking is proposed for the bus cruising downhill. The impact of lead-acid battery's charge acceptance ability over a long charging period on the regenerative braking force of a driving motor is analyzed. Dynamic model of the bus on long downhill is established. A double-manifold variable structure controller is designed for the DCMEB on long downhill. The simulation result shows that the control system maintains enough stability and strong robustness. It may be achieved for the bus to maintain a constant speed downhill only by regenerative braking on a smaller slope. But the dynamic process is very slow. When deceleration or a constant speed is desired on a larger slope, only by electro mechanical parallel braking can the bus track the target speed precisely and quickly.
Optimizing Configuration Theory Research and System Development on Electric Vehicle Power Battery
Authors: Wang Bin , Chen Xinbo
Published: October 2014

To reduce energy consumption and improve energy utilization efficiency of electric vehicles (EVs), the relationship among power battery pack, dynamics performance, and driving range is revealed in this paper. A power battery optimizing configuration model has been developed to meet the requirements of driving range and dynamics of electric vehicles, and the corresponding design steps are given in this paper. A set of special software of power battery optimization configuration for electric vehicles is developed, which is both convenient and practical. A case was employed to validate the accuracy of the power battery optimizing configuration system software.
Sparse-filtering in directional lifting wavelet transform domain based Bayesian compressive sensing
Authors: Hou Xingsong , Zhang Lan , Chen Zan , Gong Chen
Published: October 2014

Compressive sensing (CS) has been proposed for images that are sparse under a certain transform domain. However, many natural images are not strictly sparse in the transform domain, causing a tail-folding effect that degrades the performance of the CS reconstruction. To decrease such effect, a sparse-filtering (SF) in Directional Lifting Wavelet Transform (DLWT) domain based Bayesian compressive sensing (BCS) algorithm (DLWT-SF-TSW-BCS) is proposed. At the encoder, DLWT, an efficient multi-scale geometrical analysis (MGA) tool, is used to produce the sparse representation for natural images. Then sparse-filtering is adopted to cut off the small DLWT coefficients before random measurement. At the decoder, the interscale tree-structure redundancy in DLWT domain is further exploited in Bayesian reconstruction. Experimental results show that the proposed DLWT-SF-TSW-BCS algorithm significantly outperforms other state-of-the-art CS reconstruction algorithms, for example, peak signal to noise ratio (PSNR) gain up to 10.00 dB over the tree structured wavelet compressive sensing (TSW-CS).