bluuebunny/crossref_metadata_2025 huggingface dataset:
NONLINEAR ESTIMATION OF RESPIRATORY DYNAMICS OF FRESH‐CUT SPINACH (SPINACIA OLERACEA) BASED ON ENZYME KINETICS
Authors: KAUR PREETINDER , RAI DEEPAK RAJ , PAUL SHASHI
Published: October 2010

The respiratory behavior of fresh‐cut spinach under different temperatures and gas conditions was evaluated to develop an integrated respiration model taking into account the temperature dependence of enzyme kinetics parameters. The dependence of respiration rate on the O2 and CO2 concentrations has been described assuming the enzyme kinetics model for combined type of inhibition caused by CO2. The respiration model parameters under the specified environmental conditions of 10, 15, 20C and 75% relative humidity were estimated using non‐linear regression technique and were utilized to predict the rates of respiration for O2 consumption and CO2 evolution. Mixed type of inhibition was observed at all the temperatures, but changed from predominantly competitive at 10 and 15C to predominantly uncompetitive at 20C. The enzyme kinetics parameters were analyzed according to Arrhenius law, as well as simple linear and polynomial equations to determine relationships for describing their temperature dependence. The final integrated model encompassed the effect of headspace gaseous concentrations, CO2 inhibition, surrounding temperature, and can be utilized for respiratory and shelf‐life studies of different fruits and vegetables.

PRACTICAL APPLICATIONS

Fresh‐cut spinach leaves have an enormous market around the world owing to their high nutritive value. Shelf life and quality of fresh‐cut produce may be greatly reduced due to high rates of respiration. Traditional packaging, handling, storage and transportation techniques reduce the shelf life and various nutritional and phytochemical components of fresh‐cut produce. Temperature control and atmospheric modifications (low O2: 1–5% and high CO2: 5–10%) help to maintain produce quality by reducing respiration rate and enhance shelf‐life by minimizing the adverse effects of cutting in fruits and vegetables. This research has focused on determination of respiratory behavior of fresh‐cut spinach leaves at temperatures commonly encountered during transportation and retail distribution i.e., 10–15C. The results of the study show the potential of use of modified atmosphere packaging for packaging of fresh‐cut spinach leaves. Utilization of the results of this research would be of immense help in developing a user friendly program for simulating in‐pack gaseous conditions by varying the experimental parameters and in proper designing of modified atmosphere packages for storage and transportation to retail markets.
Combined in Silico and Experimental Approach for Drug Design: The Binding Mode of Peptidic and Non‐Peptidic Inhibitors to Hsp90 N‐Terminal Domain
Authors: Tomaselli Simona , Meli Massimiliano , Plescia Janet , Zetta Lucia , Altieri Dario C. , Colombo Giorgio , Ragona Laura
Published: October 2010

Heat shock protein 90 (Hsp90) is a prime target for antitumor therapies. The information obtained by molecular dynamics (MD) simulations is combined with NMR data to provide a cross‐validated atomic resolution model of the complementary interactions of heat shock protein 90 with a peptidic (shepherdin) and a non‐peptidic (5‐aminoimidazole‐4‐carboxamide‐1‐β‐d‐ribofuranoside, AICAR) inhibitor, showing antiproliferative and proapoptotic activity in multiple tumor cell lines. This approach highlights the relevant role of imidazolic moiety in the interaction of both antagonist molecules. In 5‐aminoimidazole‐4‐carboxamide‐1‐β‐d‐ribofuranoside bound state, one conformation of those present in solution is selected, where imidazolic, H4 and H5 protons have a key role in defining a non‐polar region contacting heat shock protein 90 surface. The dynamic equilibrium between N‐type and S‐type puckered forms of 5‐aminoimidazole‐4‐carboxamide‐1‐β‐d‐ribofuranoside moiety is shown to be functional to inhibitor binding. The first experimental structural data on these inhibitors are presented and discussed as hints for future design of improved molecules.
The Argument from Vagueness
Authors: Korman Daniel Z.
Published: October 2010

Universalism is the thesis that composition is unrestricted: for any non‐overlapping objects, those objects compose something. One of the most influential arguments for universalism is the argument from vagueness, first advanced by David Lewis and later elaborated and defended by Theodore Sider. I supply a reconstruction of the argument and survey a variety of responses to it.
Dual‐Process and Dual‐System Theories of Reasoning
Authors: Frankish Keith
Published: October 2010

Dual‐process theories hold that there are two distinct processing modes available for many cognitive tasks: one (type 1) that is fast, automatic and non‐conscious, and another (type 2) that is slow, controlled and conscious. Typically, cognitive biases are attributed to type 1 processes, which are held to be heuristic or associative, and logical responses to type 2 processes, which are characterised as rule‐based or analytical. Dual‐system theories go further and assign these two types of process to two separate reasoning systems, System 1 and System 2 – a view sometimes described as ‘the two minds hypothesis’. It is often claimed that System 2 is uniquely human and the source of our capacity for abstract and hypothetical thinking. This study is an introduction to dual‐process and dual‐system theories. It looks at some precursors, surveys key work in the fields of learning, reasoning, social cognition and decision making, and identifies some recent trends and philosophical applications.
Leibniz on Divine Concurrence
Authors: Whipple John
Published: October 2010

In this paper I examine G. W. Leibniz’s view on the debate between occasionalists, mere conservationists, and concurrentists. Although commentators agree that Leibniz wants to reject occasionalism and mere conservationism, there is considerable disagreement about whether Leibniz is committed to a theory of divine concurrence that differs from occasionalism and mere conservationism in principled ways. I critically assess three interpretations of Leibniz’s theory in this paper. The first two (those of Robert Adams and Sukjae Lee) differ with respect to important details, but they both assume that Leibniz straightforwardly affirms the continual creation doctrine. I argue that a coherent Leibnizian theory of divine concurrence cannot be constructed on the ontological framework that the continual creation doctrine provides. The third interpretation that I consider holds that Leibniz is willing to affirm the continual creation doctrine only to the extent that it provides an acceptable way of characterizing the dependence of finite substances on God at the level of appearances. It is suggested that Leibniz’s deep metaphysical view of creation and conservation is that in a single act God creates and conserves substances that are non‐spatial and atemporal at the deepest level of metaphysical rigor. I argue that this alternative account of creation and conservation provides a promising ontological framework that can support a coherent theory of creaturely activity that does not collapse into occasionalism or mere conservationism.
Controversy of proton pump inhibitor and clopidogrel interaction: A review
Authors: TAN HJ
Published: October 2010

A proton pump inhibitor (PPI) is often co‐prescribed with clopidogrel to reduce the gastrointestinal risk of bleeding ulcers in patients following acute coronary syndrome or a stent implant. However, the safety issue of such practice has been scrutinized after some studies reporting an increased incidence of cardiovascular events and mortality, although there have also been contrary research reports. This has lead to a warning statement from the US Food and Drug Administration cautioning the concomitant use of PPI and clopidogrel. This review examines the evidence of PPI as gastroprotective agent, histamine H2 antagonists as an alternative therapy, the influence of PPI on the antiplatelet effect of clopidogrel, and the controversies of various studies.
Unnecessary roughness? Testing the hypothesis that predators destined for molecular gut‐content analysis must be hand‐collected to avoid cross‐contamination
Authors: GREENSTONE MATTHEW H. , WEBER DONALD C. , COUDRON THOMAS C. , PAYTON MARK E.
Published: October 2010

Molecular gut‐content analysis enables detection of arthropod predation with minimal disruption of ecosystem processes. Mass‐collection methods, such as sweep‐netting, vacuum sampling and foliage beating, could lead to regurgitation or rupturing of predators along with uneaten prey, thereby contaminating specimens and compromising resultant gut‐content data. Proponents of this ‘cross‐contamination hypothesis’ advocate hand‐collection as the best way to avoid cross‐contamination. However, hand‐collection is inefficient when large samples are needed, as with most ecological research. We tested the cross‐contamination hypothesis by setting out onto potato plants immature Coleomegilla maculata and Podisus maculiventris that had been fed larvae of either Leptinotarsa decemlineata or Leptinotarsa juncta, or unfed individuals of these predator species along with L. decemlineata larvae. The animals were then immediately re‐collected, either by knocking them vigorously off the plants onto a beat cloth and capturing them en masse with an aspirator (‘rough’ treatment) or by hand‐searching and collection with a brush (‘best practice’). Collected predators were transferred in the field to individual vials of chilled ethanol and subsequently assayed by PCR for fragments of cytochrome oxidase I of L. decemlineata and L. juncta. Ten to 39 per cent of re‐collected fed predators tested positive by PCR for DNA of both Leptinotarsa species, and 14–38% of re‐collected unfed predators contained L. decemlineata DNA. Overall levels of cross‐contamination in the rough (31%) and best‐practice (11%) samples were statistically different and supported the cross‐contamination hypothesis. A pilot study on eliminating external DNA contamination with bleach prior to DNA extraction and amplification gave promising results.
MorphoJ: an integrated software package for geometric morphometrics
Authors: KLINGENBERG CHRISTIAN PETER
Published: October 2010

Increasingly, data on shape are analysed in combination with molecular genetic or ecological information, so that tools for geometric morphometric analysis are required. Morphometric studies most often use the arrangements of morphological landmarks as the data source and extract shape information from them by Procrustes superimposition. TheMorphoJ software combines this approach with a wide range of methods for shape analysis in different biological contexts. The program offers an integrated and user‐friendly environment for standard multivariate analyses such as principal components, discriminant analysis and multivariate regression as well as specialized applications including phylogenetics, quantitative genetics and analyses of modularity in shape data.MorphoJ is written in Java and versions for the Windows, Macintosh and Unix/Linux platforms are freely available fromhttp://www.flywings.org.uk/MorphoJ_page.htm.
Alteration and Reformation of Hydrocarbon Reservoirs and Prediction of Remaining Potential Resources in Superimposed Basins
Authors: Hong PANG , Xiongqi PANG , Haijun YANG , Changsong LIN , Qingyang MENG , Huaijie WANG
Published: October 2010

Complex hydrocarbon reservoirs developed widely in the superimposed basins of China formed from multiple structural alterations, reformation and destruction of hydrocarbon reservoirs formed at early stages. They are characterized currently by trap adjustment, component variation, phase conversion, and scale reformation. This is significant for guiding current hydrocarbon exploration by revealing evolution mechanisms after hydrocarbon reservoir formation and for predicting remaining potential resources. Based on the analysis of a number of complex hydrocarbon reservoirs, there are four geologic features controlling the degree of destruction of hydrocarbon reservoirs formed at early stages: tectonic event intensity, frequency, time and caprock sealing for oil and gas during tectonic evolution. Research shows that the larger the tectonic event intensity, the more frequent the tectonic event, the later the last tectonic event, the weaker the caprock sealing for oil and gas, and the greater the volume of destroyed hydrocarbons in the early stages. Based on research on the main controlling factors of hydrocarbon reservoir destruction mechanisms, a geological model of tectonic superimposition and a mathematical model evaluating potential remaining complex hydrocarbon reservoirs have been established. The predication method and technical procedures were applied in the Tazhong area of Tarim Basin, where four stages of hydrocarbon accumulation and three stages of hydrocarbon alteration occurred. Geohistorical hydrocarbon accumulation reached 3.184 billion tons, of which 1.271 billion tons were destroyed. The total volume of remaining resources available for exploration is ∼1.9 billion tons.
Origin of Crude Oil in the Lunnan Region, Tarim Basin
Authors: Sumei LI , Xiongqi PANG , Haijun YANG , Zhongyao XIAO , Qiaoyuan GU , Baoshou ZHANG , Haijiang WANG
Published: October 2010

The oil source of the Tarim Basin has been controversial over a long time. This study characterizes the crude oil and investigates the oil sources in the Lunnan region, Tarim Basin by adopting compound specific isotopes of n‐alkanes and biomarkers approaches. Although the crude oil has a good correlation with the Middle‐Upper Ordovician (O2+3) source rocks and a poor correlation with the Cambrian‐Lower Ordovician (∈‐O1) based on biomarkers, the ş13C data of n‐alkanes of the Lunnan oils show an intermediate value between ∈‐O1 and O2+3 genetic affinity oils, which suggests that the Lunnan oils are actually of an extensively mixed source. A quantification of oil mixing was performed and the results show that the contribution of the Cambrian‐Lower Ordovician source rocks ranges from 11% to 70% (averaging 36%), slightly less than that of the Tazhong uplift. It is suggested that the inconsistency between the biomarkers and δ13C in determining the oil sources in the Lunnan Region results from multiple petroleum charge episodes with different chemical components in one or more episode(s) and different sources. The widespread marine mixed‐source oil in the basin indicates that significant petroleum potential in deep horizons is possible. To unravel hydrocarbons accumulation mechanisms for the Lunnan oils is crucial to further petroleum exploration and exploitation in the region.
Tectono‐thermal Evolution in the Bachu Uplift, Tarim Basin, China
Authors: Nansheng QIU , Guang JIANG , Qinghua MEI , Shengjun WANG
Published: October 2010

The thermal evolution of source rocks in the Paleozoic has long been a problem to petroleum exploration in the Bachu uplift, Tarim basin, since the thermal history in the Paleozoic could not be rebuilt objectively due to lack of effective thermal indicators in the Lower Paleozoic successions. The apatite and zircon (U‐Th)/He thermochronometry can be used as a new kind of technique to study the thermal history and tectonic uplift of sedimentary basins. Based on the measured apatite and zircon (U‐Th)/He ages, apatite fission track data and equivalence vitrinite reflectance (%EVRo), the tectonothermal histories in 5 wells of the Bachu uplift were modeled. The modeling results show that there was relatively high gradient at the Early Paleozoic in the Bachu uplift and it decreased gradually during the entire Paleozoic: 33–35°C/km in the Cambrian‐Ordovician, 32–33°C/km in the Silurian‐Devonian, 30–32°C/km at the end of Carboniferous and 27.5–31°C/km at the end of Permian. Therefore, the thermal history can be modeled by combining multiple thermal indicators of AFT, (U‐Th)/He ages and EVRo data. Especially, this provides a new method to rebuild the thermal history for the Low Paleozoic carbonate successions in the Tarim Basin.
Effects of Near‐Surface Absorption on Reflection Characteristics of Continental Interbedded Strata: the Dagang Oilfield as an Example
Authors: Guofa LI , Mingqiang CAO , Hui ZHOU
Published: October 2010

Due to the effects of seismic wave field interference, the reflection events generated from interbedded and superposed sand and shale strata no longer have an explicit corresponding relationship with the geological interface. The absorption of the near‐surface layer decreases the resolution of the seismic wavelet, intensifies the interference of seismic reflections from different sand bodies, and makes seismic data interpretation of thin interbedded strata more complex and difficult. In order to concretely investigate and analyze the effects of the near‐surface absorption on seismic reflection characteristics of interbedded strata, and to make clear the ability of current technologies to compensate the near‐surface absorption, a geological model of continental interbedded strata with near‐surface absorption was designed, and the prestack seismic wave field was numerically simulated with wave equations. Then, the simulated wave field was processed by the prestack time migration, the effects of near‐surface absorption on prestack and poststack reflection characteristics were analyzed, and the near‐surface absorption was compensated for by inverse Q‐filtering. The model test shows that: (1) the reliability of prediction and delineation of a continental reservoir with AVO inversion is degraded due to the lateral variation of the near‐surface structure; (2) the corresponding relationships between seismic reflection events and geological interfaces are further weakened as a result of near‐surface absorption; and (3) the current technology of absorption compensation probably results in false geological structure and anomaly. Based on the model experiment, the real seismic data of the Dagang Oil Field were analyzed and processed. The seismic reflection characteristics of continental interbedded strata were improved, and the reliability of geological interpretation from seismic data was enhanced.
Citrullinated peptide and its relevance to rheumatoid arthritis: an update
Authors: LUBAN Stanislav , LI Zhan‐Guo
Published: October 2010

Citrullinated peptides in autoimmune diseases have been extensively studied in the last two decades. It is suggested that citrullination and the anti‐citrullinated peptide antibodies (ACPA) plays a critical role in initiating inflammatory responses in autoimmune diseases, such as rheumatoid arthritis (RA). The most commonly accepted molecular mechanism for citrullinated peptides/proteins in RA is that the modified antigen resulting from cell damage or uncontrolled apoptosis could evoke an immune response leading to autoantibodies against these peptide or the whole protein. Citrullination of arginine is catalyzed by the enzyme peptidylarginine‐deiminase (PAD) in the presence of calcium, changing the positively charged arginine to a polar but neutral citrulline. These citrullinated peptides/proteins and the relevant antibodies (ACPA) are important, not only in initiation of RA, but also in the diagnosis of the disease. In this evidence‐based clinical review, we summarize recently published data on peptide citrullination and ACPA gauging the ability of anti‐cyclic citrullinated peptide (anti‐CCP) antibodies for diagnosis of RA. We also recapitulate results of studies elucidating the mechanism underlying the disease.
Local Crater Wear Prediction Using Physics-Based Models
Authors: Olortegui-Yume Jorge A. , Kwon Patrick Y.
Published: October 2010

A physics-based, pointwise model is developed to predict crater profiles of multilayer coated carbides after a series of turning experiments. Dissolution and abrasion mechanisms, which are identified to be the dominant wear mechanisms at the crater, are reformulated into a pointwise or local quantity to predict the crater profiles based on the temperature and pressure profiles from finite element (FE) simulations. The crater profiles predicted by the proposed model have to be adjusted, however, due to the creep deformation of the carbide substrate occurring under the machining conditions employed in our experiment. The crater predictions correlate pretty well with the crater profiles experimentally observed in the multilayer (TiN–Al2O3–TiCN) coated carbides until the wear front reached the middle of the Al2O3 layer. At this point, the Al2O3 coating undergoes the κ-to-α-phase transformation, which makes the wear prediction difficult due to substantial changes in the thermomechanical properties of the Al2O3 coating.
Parametric Study of Acoustic Excitation-Based Glycerol-Water Microsphere Fabrication in Single Nozzle Jetting
Authors: Herran C. Leigh , Wang Wei , Huang Yong , Mironov Vladimir , Markwald Roger
Published: October 2010

Microspheres or droplets are increasingly finding various biomedical applications as drug microspheres and multicellular spheroids. Single nozzle-based continuous jetting with the help of acoustic excitation and/or carrier stream is a basic process for monodisperse microsphere fabrication. Precise control of microsphere size and size distribution in single nozzle jetting is still of great manufacturing interest. The objective of this study is to numerically model a glycerol-water microsphere fabrication process during acoustic excitation-based single nozzle continuous jetting. Using a volume of fluid method, this study has investigated the effects of material properties and fabrication conditions such as the acoustic excitation frequency and amplitude and the carrier stream velocity on the size of microspheres fabricated. (1) The microsphere diameter decreases as the glycerol volume percentage increases. (2) The excitation frequency and pressure have a pronounced effect on the microsphere size. The microsphere diameter decreases as the excitation frequency increases, and the microsphere diameter increases with the excitation pressure amplitude. (3) The microsphere size decreases as the carrier stream velocity increases.
Laser Transmission Welding of Nylon Tubes and Plates
Authors: Kritskiy A , Zak G. , Bates P. J.
Published: October 2010

In this study, nylon tubes were welded to nylon plaques using laser transmission welding. A conical mirror inserted inside the tube was used to guide the laser beam along the weld path around the inner circumference of the tube. The effect of beam location with respect to the tip of conical mirror on beam distortion was modeled and assessed experimentally. The effects of the laser power, the angular speed, and the number of passes on the joint shear strength were examined. Process parameters that gave good joint strengths were identified.
Tool Orientation Optimization Considering Second Order Kinematical Performance of the Multi-Axis Machine
Authors: Ye Tao , Xiong Cai-Hua , Xiong You-Lun , Zhao Can
Published: October 2010

This paper presents a new tool orientation optimization approach for multi-axis machining considering up to second order kinematical performance of the multi-axis machine. Different from the traditional optimization approach, tool orientations are optimized with the goal of improving the kinematical performance of the machining process, not only increasing the material removal from purely geometrical aspect. The procedure is to first determine a few key orientations on the part surface along the tool path according to the curvature variation. Key orientations are initially optimized to be able to achieve high material removal by comparing the tool swept curve and the actual part surface. Intermediate orientations between key orientations are interpolated smoothly using rigid body interpolation techniques on SO(3). The time-optimal trajectory planning problem with velocity and acceleration constraints of the multi-axis machine is then solved to adjust the initially determined tool orientations to better exploit the multi-axis machine’s motion capacity. Simulation and experiment validate the feasibility and effectiveness of the proposed approach.
Effect of Microstructural Parameters on the Machinability of Aligned Carbon Nanotube Composites
Authors: Samuel Johnson , Kapoor Shiv G. , DeVor Richard E. , Hsia K. Jimmy
Published: October 2010

The objective of this paper is to understand through parametric studies the effect of microstructural parameters, viz., the carbon nanotube (CNT) orientation with respect to the cutting direction, CNT loading, and level of dispersion within the matrix on the machinability of aligned CNT composites. To this end, a microstructure-based finite element machining model is used to simulate microstructures containing 1.5% and 6% by weight of CNTs. Microstructures with both uniform and nonuniform dispersions of CNTs are simulated. For each of these cases, CNTs having orientations of 0 deg, 45 deg, 90 deg, and 135 deg to the cutting direction are studied. The machining simulations were conducted using a positive rake tool. Chip morphology, cutting forces, surface roughness, and surface/subsurface damages are the machinability measures used for comparison. The results of the parametric studies demonstrate that the CNT orientation, loading, and level of dispersion all play a critical role in dictating the machining response of aligned composites. The results further indicate that the surface morphology of the machined surface can be harnessed to produce the next generation of microfluidic devices. This application demonstrates the feasibility of designing the microstructure of CNT composites by taking into account both their engineering functionality and machinability.
Mahalanobis Taguchi System (MTS) as a Prognostics Tool for Rolling Element Bearing Failures
Authors: Soylemezoglu Ahmet , Jagannathan S. , Saygin Can
Published: October 2010

In this paper, a novel Mahalanobis–Taguchi system (MTS)-based fault detection, isolation, and prognostics scheme is presented. The proposed data-driven scheme utilizes the Mahalanobis distance (MD)-based fault clustering and the progression of MD values over time. MD thresholds derived from the clustering analysis are used for fault detection and isolation. When a fault is detected, the prognostics scheme, which monitors the progression of the MD values, is initiated. Then, using a linear approximation, time to failure is estimated. The performance of the scheme has been validated via experiments performed on rolling element bearings inside the spindle headstock of a microcomputer numerical control (CNC) machine testbed. The bearings have been instrumented with vibration and temperature sensors and experiments involving healthy and various types of faulty operating conditions have been performed. The experiments show that the proposed approach renders satisfactory results for bearing fault detection, isolation, and prognostics. Overall, the proposed solution provides a reliable multivariate analysis and real-time decision making tool that (1) presents a single tool for fault detection, isolation, and prognosis, eliminating the need to develop each separately and (2) offers a systematic way to determine the key features, thus reducing analysis overhead. In addition, the MTS-based scheme is process independent and can easily be implemented on wireless motes and deployed for real-time monitoring, diagnostics, and prognostics in a wide variety of industrial environments.
Distributed Hydrogen Technologies for Commercial Buildings and Vehicle Refueling
Authors: Jalalzadeh-Azar Ali A.
Published: October 2010

This paper examines the potential energy, environmental, and economic benefits of hydrogen-based distributed generation (DG) systems with dual application—commercial buildings and vehicle refueling. The selected DG systems incorporate fuel cell technologies for power generation and natural gas reformation for hydrogen production. In addition to basic systems, more advanced configurations facilitating heat recovery for the reformer and the building heating equipment are considered. Integration of stationary and transportation applications within the context of a commercial community is also explored on the premise of utilizing a joint hydrogen production facility for cost reduction. While appreciable improvement in greenhouse gas (GHG) emissions is evidently intrinsic to all selected stationary DG models, a significant reduction in the primary energy use is achieved with the more-advanced systems, particularly the one with internal heat recovery. A negligible impact on the water consumption is registered when water management is in place for the fuel cell systems. The integration strategy highlighting the community buildings as the surrogate supplier of hydrogen for vehicle refueling is more tenable from the economic standpoint than the reversed arrangement.
Modeling On-Sun Tests of a Prototype Solid Particle Receiver for Concentrating Solar Power Processes and Storage
Authors: Ho Clifford K. , Khalsa Siri S. , Siegel Nathan P.
Published: October 2010

A model has been developed to simulate the performance of a prototype solid particle receiver that was recently tested at Sandia National Laboratories. The model includes irradiation from the concentrated solar flux, two-band re-radiation and emission with the cavity, discrete-phase particle transport and heat transfer, gas-phase convection, wall conduction, and radiative and convective heat losses. Simulated temperatures of the particles and cavity walls were compared to measured values for nine on-sun tests. Results showed that the simulated temperature distributions and receiver efficiencies matched closely with trends in experimental data as a function of input power and particle mass flow rate. The average relative error between the simulated and measured efficiencies and increases in particle temperature was less than 10%. Simulations of particle velocities and concentrations as a function of position beneath the release point were also evaluated and compared to measured values collected during unheated tests with average relative errors of 6% and 8%, respectively. The calibrated model is being used in parametric analyses to better understand the impact and interactions of multiple parameters with a goal of optimizing the performance and efficiency of the solid particle receiver.
Life Cycle Assessment of the Energy Independence and Security Act of 2007: Ethanol—Global Warming Potential and Environmental Emissions
Authors: Heath Garvin A. , Hsu David D. , Inman Daniel , Aden Andy , Mann Margaret K.
Published: October 2010

Strategies to reduce the dependence of the United States on foreign oil, increase the use of renewable energy, and lessen the contribution to global warming have received significant attention. National adoption of such strategies could significantly impact America’s economy and security as well as global climate change. The Energy Independence and Security Act of 2007 (EISA) mandates specific renewable energy market penetration targets for the year 2022 [1]. For liquid transportation fuels, the 2022 EISA mandate is 36 billion gallons per year (bgy) of biofuel, of which 21 bgy must come from feedstocks other than corn starch. Despite this legal mandate for renewable biofuels, many questions remain unanswered with regard to the potential environmental effects of such a large increase in the production and use of biofuels. In addition to specifying volumetric standards for these renewable fuels, EISA establishes greenhouse gas mitigation standards. The objective of this study is to use life cycle assessment (LCA) to evaluate the global warming potential (GWP), water use, and net energy value (NEV) associated with the EISA-mandated 16 bgy cellulosic biofuels target, which is assumed in this study to be met by cellulosic-based ethanol, and the EISA-mandated 15 bgy conventional corn ethanol target. Specifically, this study compares, on a per-kilometer-driven basis, the GWP, water use, and NEV for the year 2022 for several biomass feedstocks.
CO2 Splitting in a Hot-Wall Aerosol Reactor via the Two-Step Zn/ZnO Solar Thermochemical Cycle
Authors: Loutzenhiser Peter G. , Ga´lvez M. Elena , Hischier Illias , Stamatiou Anastasia , Steinfeld Aldo
Published: October 2010

Using concentrated solar energy as the source of high-temperature process heat, a two-step CO2 splitting thermochemical cycle based on Zn/ZnO redox reactions is applied to produce renewable carbon-neutral fuels. The solar thermochemical cycle consists of: 1) the solar endothermic dissociation of ZnO to Zn and O2; 2) the non-solar exothermic reduction of CO2 with Zn to CO and ZnO; the latter is the recycled to the 1st solar step. The net reaction is CO2 = CO + 1/2 O2, with products formed in different steps, thereby eliminating the need for their separation. A Second-Law thermodynamic analysis indicates a maximum solar-to-chemical energy conversion efficiency of 39% for a solar concentration ratio of 5000 suns. The technical feasibility of the first step of the cycle has been demonstrated in a high-flux solar furnace with a 10 kW solar reactor prototype. The second step of the cycle is experimentally investigated in a hot-wall quartz aerosol flow reactor, designed for in-situ quenching of Zn(g), formation of Zn nanoparticles, and oxidation with CO2. The effect of varying the molar flow ratios of the reactants was investigated. Chemical conversions were determined by gas chromatography and X-ray diffraction. Chemical conversions of Zn to ZnO of up to 88% were obtained for a residence time of ∼ 3.05 s. For all of the experiments, the reactions primarily occurred outside the aerosol jet flow on the surfaces of the reaction zone.
Analysis of Application of Pressure Exchange Device in Thermal Vapor Compression Desalination System
Authors: Chabukswar Kaustubh A. , Garris Charles A.
Published: October 2010

Recent advances in direct fluid-fluid flow induction provide potential for major improvement in performance of thermal distillation systems based on the pressure exchange phenomenon compared to the conventional turbulent mixing controlled ejectors. Pressure exchange devices utilize the work of nonsteady pressure forces acting across moving interfaces. Optimal performances of such devices can be determined through the use of the ideal turbomachinery analog. The analog is configured as a turbine-compressor unit, where the high energy primary fluid expands through the turbine that drives a compressor which compresses the low energy secondary fluid and the two then discharges in a common mixing chamber at a common intermediate pressure. The overall functioning of the turbomachinery analog is similar to the conventional ejector. Thus the turbomachinery analog provides the highest possible performance that an ejector can achieve ideally. An analytical single effect thermal vapor compression (TVC) desalination model is developed. The turbomachinery analog which is the simplest kind of pressure exchange device is simulated in place of the conventional ejector. The objective of the research is to investigate the performance of the system for various ejector efficiencies, so as to achieve the minimum production cost of distilled water. Such a development would make the process comparable with reverse osmosis and mechanical vapor compression desalination system. The system performance is expressed in the form of thermal performance ratio. For similar systems employing conventional steady-state ejectors, thermal performance ratios as high as 2 has been achieved for low compression ratio and low boiling temperature but at a price of high pressure primary steam. This paper reveals that the application of pressure exchange device can achieve even greater performance ratios for lower primary pressure and temperatures, contributing to a significant decrease in production cost. The model is designed for 5m3/day capacity, with an aim of achieving highest possible thermal efficiency. The system is analyzed by varying the critical operating parameters, like compression ratio, top brine temperature, primary pressure and ejector efficiency. The results show that with increase in primary pressure, the required primary temperature goes down. Also the application of pressure exchange device results in a phenomenal 3 fold rise in thermal performance ratio, as compared to conventional ejectors. The results achieved from the simulations are quite encouraging and promising for the future development of more efficient and compact device called the supersonic pressure exchange ejector.
Optimized Solar Collector
Authors: Larsen Ted
Published: October 2010

Fundamental to the design of solar trough collectors is that a suitable structure must be provided for positioning and support of mirrors, as well as pipes for transporting heat transfer fluids. These elements and related hardware are basic to the level of investment necessary for fabrication of collectors. An objective of system optimization is to design structures so that they are capable of more than one useful function, and to achieve this with little or no added cost. Two valuable commodities, Thermal Energy and Potable Water, can be accessed through design innovation, using the same basic structure, and without interfering with efficient harvest of either commodity. Additional design opportunities are implicit in the fact that solar collectors must operate in open air. To explore means for mitigating resultant operational and maintenance problems, a 1/4 scale version of a one meter focal length collector was built and tested. Using hinged mirror panels that open and close like a clamshell, the assembly can assume several distinct configurations. These include solar concentrator mode, protective storage, mirror cleaning, solar rejection, and harvest of ambient moisture. Of particular interest for smaller applications, all features can be incorporated into a dedicated “Unitized” assembly, ideal for application on industrial or commercial buildings.
Performance Evaluation for Micro-Turbine Using Modified TOPSIS With Objective Weights
Authors: Shi Guohua , Jing Youyin , Gao Yuefen , Zheng Guozhong
Published: October 2010

Micro-turbine is paid more and more attention in scientific research and commercial application with the development of distribution generation (DG) in the global range. It is essential to make a synthetic and scientific evaluation on the performance of micro-turbine in order to promote the progress of the distributed generation technology using micro-turbine. This study presents the synthetic performance evaluation of micro-turbine. Some performance characters (rated capacity, generating efficiency, overall system efficiency, unit cost, fuel consumption, multi-fuel, NOx emission level, noises and life time) are chosen as evaluating criterions and some common micro-turbines are taken as evaluating objects in this paper. Considering the difficulty of fuzzy synthetic evaluation method in calculation of the multiple factors and the ignorance of the relationship among evaluating objects, a modified TOPSIS with objective weights is introduced and applied in performance assessment of the micro-turbines. Each criterion weight is calculated based on Shannon’s entropy concept. The evaluation result of the example shows that this approach is favorable for fuzzy synthetic evaluation of micro-turbine performance, particularly applicable for situations where reliable subjective weights from experts cannot be obtained. The evaluation results can also be as references for manufactures how to improve design of micro-turbines and for users how to make proper selection of micro-turbines.
Economical Design of Wind-Solar Hybrid Renewable Energy Systems
Authors: Stewart Susan W. , Witmer Lucas T.
Published: October 2010

Every location on Earth has its own unique set of natural resources to draw upon for sustainable energy production. As these resources are generally of an intermittent nature, hybrid systems will be necessary in many situations to achieve economical energy independence while meeting our inconsistent demands for electricity with minimal or no energy storage. Wind and solar resources often have complimentary attributes that combined can more closely match energy load requirements. This match can be customized for optimum economy by adjusting the orientation and design of the PV system as well as the rotor length and generator size of the wind turbine system. Different load requirements and electricity rate structures require a different design approach in order to achieve optimum cost savings. Using the Penn State SURFRAD wind speed and solar radiation data set the design process for solar-wind hybrid renewable energy systems is explored for the case of a grid-tied residential scale application with a time of use electricity rate structure.
Advances in Near-Optimal Control of Passive Building Thermal Storage
Authors: Henze Gregor P. , Florita Anthony R. , Brandemuehl Michael J. , Felsmann Clemens , Cheng Hwakong
Published: October 2010

Using a simulation and optimization environment, this paper presents advances towards near-optimal building thermal mass control derived from full factorial analyses of the important parameters influencing the passive thermal storage process for a range of buildings and climate/utility rate structure combinations. Guidelines for the application of, and expected savings from, building thermal mass control strategies that can be easily implemented and result in a significant reduction in building operating costs and peak electrical demand are sought. In response to the actual utility rates imposed in the investigated cities, fundamental insights and control simplifications are derived from those buildings deemed suitable candidates. The near-optimal strategies are derived from the optimal control trajectory, consisting of four variables, and then tested for effectiveness and validated with respect to uncertainty regarding building parameters and climate variations. Due to the overriding impact of the utility rate structure on both savings and control strategy, combined with the overwhelming diversity of utility rates offered to commercial building customers, the study cannot offer universally valid control guidelines. Nevertheless, a significant number of cases, i.e. combinations of buildings, weather, and utility rate structure, have been investigated, which offer both insight and recommendations for simplified control strategies. These guidelines represent a good starting point for experimentation with building thermal mass control for a substantial range of building types, equipment, climates, and utility rates.
Combustion of Apple Juice Wastes in a Cyclone Combustor for Thermal Energy Generation
Authors: Virmond Elaine , Schacker Robson L. , Albrecht Waldir , Althoff Christine A. , de Souza Mauri´cio , Moreira Regina F. P. M. , Jose´ Humberto J.
Published: October 2010

The thermal conversion of biomass fuels using different combustion technologies has increased worldwidely in the latest years due to the energetic exploitation potential of wastes as well as to the strong increase of environmental consciousness in the industrial sector. In this work the bagasse obtained from the apple juice industry (AB) was characterized and the gaseous emissions resulting from its combustion in a pilot scale cyclone combustor were measured and compared to limits imposed by Brazilian and international current legislations. Wood and wood-based materials are extensively used as fuel for thermal energy generation particularly in the Brazilian food industry, which demands large amounts of steam. Considering that, sawdust (SD) was also characterized, burned in the same conditions and the gaseous emissions analyzed for comparison purposes. Sampling for the volatile organic compounds benzene, toluene, ethyl-benzene and xylene (BTEX, expressed as total organic carbon, TOC) and polycyclic aromatic hydrocarbons (PAH) were performed and the samples analyzed by gaseous chromatography-mass spectrometry (GC-MS). Chemical properties showed that the volatile matter value of AB is high (85.36 wt%, daf) what indicates that the solid burn rapidly. The absence of sulfur in its composition represents an advantage in relation to fossil fuels because its combustion does not release sulfur derived compounds. The lower heating value is 21.09 MJ.kg−1 (daf), 26.9% higher than the heating value of SD (16.62 MJ.kg−1). The effect of the N fuel content found in AB composition was clearly noticed through the high NOx concentration in the flue gas resulted from its burning. Comparing the properties and the burning profiles of SD and AB, it can be stated that this industrial waste obtained from the apple juice industry is suitable for direct combustion, constituting a renewable energy source for this industrial sector, however, measures as air staging and staged addition of fuel, or flue gas cleaning technologies would be required for reducing the NOx emission. Concerning the presence of toxic compounds as PAH, they were not detected once the operation conditions applied resulted in controlled gaseous emissions and temperature profile. Also, TOC concentrations remained below the regulations limits considered.
Analysis of the Thermodynamic Performance of Kalina Cycle System 11 (KCS11) for Geothermal Power Plant: Comparison With Kawerau ORMAT Binary Plant
Authors: Lu Xinli , Watson Arnold , Deans Joe
Published: October 2010

Since the first geothermal power plant was built at Larderello (Italy) in 1904, many attempts have been made to improve conversion efficiency. Among innovative technologies, using the Kalina cycle is considered as one of the most effective means of enhancing the thermodynamic performance for both high and low temperature heat source systems. Although initially used as the bottoming cycle of gas turbines and diesel engines, in the late 1980s the Kalina cycle was found to be attractive for geothermal power generation [1, 2, 3]. Different versions (KSC11, KSC12 and KSC13) were designated. Comparison between Kalina cycle and other power cycles can be found in later studies [4, 5, 6]. Here we examine KSC11, because it is specifically designed for geothermal power generation, with lower capital cost [3]. We compare this design with the existing Kawerau ORMAT binary plant in New Zealand. In addition, parametric sensitivity analysis of KCS11 has been carried out for the specific power output and net thermal efficiency by changing the temperatures of both heat source and heat sink for a given ammonia-water composition.
Performance Optimization and Parametric Design of an Irreversible Solar-Driven Three Source Heat Pump
Authors: Zhang Houcheng , Wu Lanmei , Lin Guoxing
Published: October 2010

An irreversible solar-driven heat pump system operating among three heat sources at different temperatures is investigated, in which not only finite-rate heat transfer between the cycle working fluid and the three heat sources but also the internal irreversibility inside the cyclic working fluid, the radiation heat loss of the solar collector are taken into account. Based on thermodynamics analysis method and the optimal control theory, the relation between the overall coefficient of performance (COP) of the solar-driven three source heat pump system and the operating temperature of the solar collector is derived. An optimal matching between the solar collector and the three source heat pump is determined and the optimal operating temperature of the solar collector is explored. Furthermore, the influences of the radiation heat loss of the collector, the internal irreversibility and the comprehensive factor, etc. on the performance characteristic of the solar-driven three source heat pump system are analyzed and evaluated. By means of the numerical value calculation, the optimal design parameters and performance characteristics of the solar-driven three source heat pump system are discussed in detail. The results obtained may provide some theoretical references for the parametric design and performance evaluation of solar-driven absorption/adsorption heat pumps.